[v12,08/12] landlock: Add network rules and TCP hooks support

Commit Message

Konstantin Meskhidze (A) Sept. 20, 2023, 9:26 a.m. UTC

This commit adds network rules support in the ruleset management
helpers and the landlock_create_ruleset syscall.
Refactor user space API to support network actions. Add new network
access flags, network rule and network attributes. Increment Landlock
ABI version. Expand access_masks_t to u32 to be sure network access
rights can be stored. Implement socket_bind() and socket_connect()
LSM hooks, which enables to restrict TCP socket binding and connection
to specific ports.
The new landlock_net_port_attr structure has two fields. The allowed_access
field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
the port value according to the allowed protocol. This field can
take up to a 64-bit value [1] but the maximum value depends on the related
protocol (e.g. 16-bit for TCP).

[1]
https://lore.kernel.org/r/[e-mail]

Signed-off-by: Mickaël Salaün <[e-mail]>
Signed-off-by: Konstantin Meskhidze <[e-mail]>
---

Changes since v11:
* Replace dates with "2022-2023" in net.c/h files headers.
* Removes WARN_ON_ONCE(!domain) in check_socket_access().
* Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family).
* Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT.
* Renames landlock_net_service_attr to landlock_net_port_attr.
* Defines two add_rule_net_service() functions according to
  IS_ENABLED(CONFIG_INET) instead of changing the body of the only
  function.
* Adds af_family consistency check while handling AF_UNSPEC specifically.
* Adds bind_access_mask in add_rule_net_service() to deny all rules with bind
  action on port zero.
* Minor fixes.
* Refactors commit message.

Changes since v10:
* Removes "packed" attribute.
* Applies Mickaёl's patch with some refactoring.
* Deletes get_port() and check_addrlen() helpers.
* Refactors check_socket_access() by squashing get_port() and
  check_addrlen() helpers into it.
* Fixes commit message.

Changes since v9:
* Changes UAPI port field to __u64.
* Moves shared code into check_socket_access().
* Adds get_raw_handled_net_accesses() and
  get_current_net_domain() helpers.
* Minor fixes.

Changes since v8:
* Squashes commits.
* Refactors commit message.
* Changes UAPI port field to __be16.
* Changes logic of bind/connect hooks with AF_UNSPEC families.
* Adds address length checking.
* Minor fixes.

Changes since v7:
* Squashes commits.
* Increments ABI version to 4.
* Refactors commit message.
* Minor fixes.

Changes since v6:
* Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
  because it OR values.
* Makes landlock_add_net_access_mask() more resilient incorrect values.
* Refactors landlock_get_net_access_mask().
* Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
  LANDLOCK_NUM_ACCESS_FS as value.
* Updates access_masks_t to u32 to support network access actions.
* Refactors landlock internal functions to support network actions with
  landlock_key/key_type/id types.

Changes since v5:
* Gets rid of partial revert from landlock_add_rule
syscall.
* Formats code with clang-format-14.

Changes since v4:
* Refactors landlock_create_ruleset() - splits ruleset and
masks checks.
* Refactors landlock_create_ruleset() and landlock mask
setters/getters to support two rule types.
* Refactors landlock_add_rule syscall add_rule_path_beneath
function by factoring out get_ruleset_from_fd() and
landlock_put_ruleset().

Changes since v3:
* Splits commit.
* Adds network rule support for internal landlock functions.
* Adds set_mask and get_mask for network.
* Adds rb_root root_net_port.

---
 include/uapi/linux/landlock.h                |  47 ++++
 security/landlock/Kconfig                    |   3 +-
 security/landlock/Makefile                   |   2 +
 security/landlock/limits.h                   |   5 +
 security/landlock/net.c                      | 241 +++++++++++++++++++
 security/landlock/net.h                      |  35 +++
 security/landlock/ruleset.c                  |  62 ++++-
 security/landlock/ruleset.h                  |  59 ++++-
 security/landlock/setup.c                    |   2 +
 security/landlock/syscalls.c                 |  33 ++-
 tools/testing/selftests/landlock/base_test.c |   2 +-
 11 files changed, 467 insertions(+), 24 deletions(-)
 create mode 100644 security/landlock/net.c
 create mode 100644 security/landlock/net.h

--
2.25.1

Comments

Mickaël Salaün Oct. 2, 2023, 8:26 p.m. UTC | #1

Thanks for this new version Konstantin. I pushed this series, with minor
changes, to -next. So far, no warning. But it needs some changes, mostly
kernel-only, but also one with the handling of port 0 with bind (see my
review below).

On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
> This commit adds network rules support in the ruleset management
> helpers and the landlock_create_ruleset syscall.
> Refactor user space API to support network actions. Add new network
> access flags, network rule and network attributes. Increment Landlock
> ABI version. Expand access_masks_t to u32 to be sure network access
> rights can be stored. Implement socket_bind() and socket_connect()
> LSM hooks, which enables to restrict TCP socket binding and connection
> to specific ports.
> The new landlock_net_port_attr structure has two fields. The allowed_access
> field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
> the port value according to the allowed protocol. This field can
> take up to a 64-bit value [1] but the maximum value depends on the related
> protocol (e.g. 16-bit for TCP).
> 
> [1]
> https://lore.kernel.org/r/[e-mail]
> 
> Signed-off-by: Mickaël Salaün <[e-mail]>
> Signed-off-by: Konstantin Meskhidze <[e-mail]>
> ---
> 
> Changes since v11:
> * Replace dates with "2022-2023" in net.c/h files headers.
> * Removes WARN_ON_ONCE(!domain) in check_socket_access().
> * Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family).
> * Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT.
> * Renames landlock_net_service_attr to landlock_net_port_attr.
> * Defines two add_rule_net_service() functions according to
>   IS_ENABLED(CONFIG_INET) instead of changing the body of the only
>   function.
> * Adds af_family consistency check while handling AF_UNSPEC specifically.
> * Adds bind_access_mask in add_rule_net_service() to deny all rules with bind
>   action on port zero.
> * Minor fixes.
> * Refactors commit message.
> 
> Changes since v10:
> * Removes "packed" attribute.
> * Applies Mickaёl's patch with some refactoring.
> * Deletes get_port() and check_addrlen() helpers.
> * Refactors check_socket_access() by squashing get_port() and
>   check_addrlen() helpers into it.
> * Fixes commit message.
> 
> Changes since v9:
> * Changes UAPI port field to __u64.
> * Moves shared code into check_socket_access().
> * Adds get_raw_handled_net_accesses() and
>   get_current_net_domain() helpers.
> * Minor fixes.
> 
> Changes since v8:
> * Squashes commits.
> * Refactors commit message.
> * Changes UAPI port field to __be16.
> * Changes logic of bind/connect hooks with AF_UNSPEC families.
> * Adds address length checking.
> * Minor fixes.
> 
> Changes since v7:
> * Squashes commits.
> * Increments ABI version to 4.
> * Refactors commit message.
> * Minor fixes.
> 
> Changes since v6:
> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
>   because it OR values.
> * Makes landlock_add_net_access_mask() more resilient incorrect values.
> * Refactors landlock_get_net_access_mask().
> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
>   LANDLOCK_NUM_ACCESS_FS as value.
> * Updates access_masks_t to u32 to support network access actions.
> * Refactors landlock internal functions to support network actions with
>   landlock_key/key_type/id types.
> 
> Changes since v5:
> * Gets rid of partial revert from landlock_add_rule
> syscall.
> * Formats code with clang-format-14.
> 
> Changes since v4:
> * Refactors landlock_create_ruleset() - splits ruleset and
> masks checks.
> * Refactors landlock_create_ruleset() and landlock mask
> setters/getters to support two rule types.
> * Refactors landlock_add_rule syscall add_rule_path_beneath
> function by factoring out get_ruleset_from_fd() and
> landlock_put_ruleset().
> 
> Changes since v3:
> * Splits commit.
> * Adds network rule support for internal landlock functions.
> * Adds set_mask and get_mask for network.
> * Adds rb_root root_net_port.
> 
> ---
>  include/uapi/linux/landlock.h                |  47 ++++
>  security/landlock/Kconfig                    |   3 +-
>  security/landlock/Makefile                   |   2 +
>  security/landlock/limits.h                   |   5 +
>  security/landlock/net.c                      | 241 +++++++++++++++++++
>  security/landlock/net.h                      |  35 +++
>  security/landlock/ruleset.c                  |  62 ++++-
>  security/landlock/ruleset.h                  |  59 ++++-
>  security/landlock/setup.c                    |   2 +
>  security/landlock/syscalls.c                 |  33 ++-
>  tools/testing/selftests/landlock/base_test.c |   2 +-
>  11 files changed, 467 insertions(+), 24 deletions(-)
>  create mode 100644 security/landlock/net.c
>  create mode 100644 security/landlock/net.h
> 
> diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
> index 81d09ef9aa50..3b8400e8a4d9 100644
> --- a/include/uapi/linux/landlock.h
> +++ b/include/uapi/linux/landlock.h
> @@ -31,6 +31,12 @@ struct landlock_ruleset_attr {
>  	 * this access right.
>  	 */
>  	__u64 handled_access_fs;
> +	/**
> +	 * @handled_access_net: Bitmask of actions (cf. `Network flags`_)
> +	 * that is handled by this ruleset and should then be forbidden if no
> +	 * rule explicitly allow them.
> +	 */
> +	__u64 handled_access_net;
>  };
> 
>  /*
> @@ -54,6 +60,11 @@ enum landlock_rule_type {
>  	 * landlock_path_beneath_attr .
>  	 */
>  	LANDLOCK_RULE_PATH_BENEATH = 1,
> +	/**
> +	 * @LANDLOCK_RULE_NET_PORT: Type of a &struct
> +	 * landlock_net_port_attr .
> +	 */
> +	LANDLOCK_RULE_NET_PORT = 2,
>  };
> 
>  /**
> @@ -79,6 +90,23 @@ struct landlock_path_beneath_attr {
>  	 */
>  } __attribute__((packed));
> 
> +/**
> + * struct landlock_net_port_attr - Network service definition

"Network port definition"


> diff --git a/security/landlock/Kconfig b/security/landlock/Kconfig
> index c1e862a38410..10c099097533 100644
> --- a/security/landlock/Kconfig
> +++ b/security/landlock/Kconfig
> @@ -2,7 +2,8 @@
> 
>  config SECURITY_LANDLOCK
>  	bool "Landlock support"
> -	depends on SECURITY
> +	depends on SECURITY && !ARCH_EPHEMERAL_INODES

!ARCH_EPHEMERAL_INODES is definitely gone now.

> +	select SECURITY_NETWORK
>  	select SECURITY_PATH
>  	help
>  	  Landlock is a sandboxing mechanism that enables processes to restrict
> diff --git a/security/landlock/Makefile b/security/landlock/Makefile
> index 7bbd2f413b3e..53d3c92ae22e 100644
> --- a/security/landlock/Makefile
> +++ b/security/landlock/Makefile
> @@ -2,3 +2,5 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o
> 
>  landlock-y := setup.o syscalls.o object.o ruleset.o \
>  	cred.o ptrace.o fs.o
> +
> +landlock-$(CONFIG_INET) += net.o
> \ No newline at end of file
> diff --git a/security/landlock/limits.h b/security/landlock/limits.h
> index bafb3b8dc677..93c9c6f91556 100644
> --- a/security/landlock/limits.h
> +++ b/security/landlock/limits.h
> @@ -23,6 +23,11 @@
>  #define LANDLOCK_NUM_ACCESS_FS		__const_hweight64(LANDLOCK_MASK_ACCESS_FS)
>  #define LANDLOCK_SHIFT_ACCESS_FS	0
> 
> +#define LANDLOCK_LAST_ACCESS_NET	LANDLOCK_ACCESS_NET_CONNECT_TCP
> +#define LANDLOCK_MASK_ACCESS_NET	((LANDLOCK_LAST_ACCESS_NET << 1) - 1)
> +#define LANDLOCK_NUM_ACCESS_NET		__const_hweight64(LANDLOCK_MASK_ACCESS_NET)
> +#define LANDLOCK_SHIFT_ACCESS_NET	LANDLOCK_NUM_ACCESS_FS
> +
>  /* clang-format on */
> 
>  #endif /* _SECURITY_LANDLOCK_LIMITS_H */
> diff --git a/security/landlock/net.c b/security/landlock/net.c
> new file mode 100644
> index 000000000000..62b830653e25
> --- /dev/null
> +++ b/security/landlock/net.c
> @@ -0,0 +1,241 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Landlock LSM - Network management and hooks
> + *
> + * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
> + * Copyright © 2022-2023 Microsoft Corporation
> + */
> +
> +#include <linux/in.h>
> +#include <linux/net.h>
> +#include <linux/socket.h>
> +#include <net/ipv6.h>
> +
> +#include "common.h"
> +#include "cred.h"
> +#include "limits.h"
> +#include "net.h"
> +#include "ruleset.h"
> +
> +int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
> +			     const u16 port, access_mask_t access_rights)

This function is only used in add_rule_net_service(), so it should not
be exported, and we can merge it (into landlock_add_rule_net_port).

> +{
> +	int err;
> +	const struct landlock_id id = {
> +		.key.data = (__force uintptr_t)htons(port),
> +		.type = LANDLOCK_KEY_NET_PORT,
> +	};
> +
> +	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
> +
> +	/* Transforms relative access rights to absolute ones. */
> +	access_rights |= LANDLOCK_MASK_ACCESS_NET &
> +			 ~landlock_get_net_access_mask(ruleset, 0);
> +
> +	mutex_lock(&ruleset->lock);
> +	err = landlock_insert_rule(ruleset, id, access_rights);
> +	mutex_unlock(&ruleset->lock);
> +
> +	return err;
> +}
> +
> +int add_rule_net_service(struct landlock_ruleset *ruleset,

We should only export functions with a "landlock_" prefix, and "service"
is now replaced with "port", which gives landlock_add_rule_net_port().

For consistency, we should also rename add_rule_path_beneath() into
landlock_add_rule_path_beneath(), move it into fs.c, and merge
landlock_append_fs_rule() into it (being careful to not move the related
code to ease review). This change should be part of the "landlock:
Refactor landlock_add_rule() syscall" patch. Please be careful to keep
the other changes happening in other patches.


> +			 const void __user *const rule_attr)
> +{
> +	struct landlock_net_port_attr net_port_attr;
> +	int res;
> +	access_mask_t mask, bind_access_mask;
> +
> +	/* Copies raw user space buffer. */
> +	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));

We should include <linux/uaccess.h> because of copy_from_user().

Same for landlock_add_rule_path_beneath().

> +	if (res)
> +		return -EFAULT;
> +
> +	/*
> +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
> +	 * are ignored by network actions.
> +	 */
> +	if (!net_port_attr.allowed_access)
> +		return -ENOMSG;
> +
> +	/*
> +	 * Checks that allowed_access matches the @ruleset constraints
> +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
> +	 */
> +	mask = landlock_get_net_access_mask(ruleset, 0);
> +	if ((net_port_attr.allowed_access | mask) != mask)
> +		return -EINVAL;
> +
> +	/*
> +	 * Denies inserting a rule with port 0 (for bind action) or
> +	 * higher than 65535.
> +	 */
> +	bind_access_mask = net_port_attr.allowed_access &
> +			   LANDLOCK_ACCESS_NET_BIND_TCP;
> +	if (((net_port_attr.port == 0) &&
> +	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||

For context about "port 0 binding" see
https://lore.kernel.org/all/[e-mail]/

I previously said:
>> > To say it another way, we should not allow to add a rule with port
>> > 0 for
>> > LANDLOCK_ACCESS_NET_BIND_TCP, but return -EINVAL in this case. This
>> > limitation should be explained, documented and tested.

Thinking more about this port 0 for bind (and after an interesting
discussion with Eric), it would be a mistake to forbid a rule to bind on
port 0 because this is very useful for some network services, and
because it would not be reasonable to have an LSM hook to control such
"random ports". Instead we should document what using this value means
(i.e. pick a dynamic available port in a range defined by the sysadmin)
and highlight the fact that it is controlled with the
/proc/sys/net/ipv4/ip_local_port_range sysctl, which is also used by
IPv6.

We then need to test binding on port zero by getting the binded port
(cf. getsockopt/getsockname) and checking that we can indeed connect to
it.

> +	    (net_port_attr.port > U16_MAX))
> +		return -EINVAL;
> +
> +	/* Imports the new rule. */
> +	return landlock_append_net_rule(ruleset, net_port_attr.port,
> +					net_port_attr.allowed_access);
> +}

> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
> index 1ede2b9a79b7..9bd0483c64d4 100644
> --- a/security/landlock/ruleset.h
> +++ b/security/landlock/ruleset.h
> @@ -33,13 +33,16 @@
>  typedef u16 access_mask_t;
>  /* Makes sure all filesystem access rights can be stored. */
>  static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS);
> +/* Makes sure all network access rights can be stored. */
> +static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET);
>  /* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */
>  static_assert(sizeof(unsigned long) >= sizeof(access_mask_t));
> 
>  /* Ruleset access masks. */
> -typedef u16 access_masks_t;
> +typedef u32 access_masks_t;
>  /* Makes sure all ruleset access rights can be stored. */
> -static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS);
> +static_assert(BITS_PER_TYPE(access_masks_t) >=
> +	      LANDLOCK_NUM_ACCESS_FS + LANDLOCK_NUM_ACCESS_NET);
> 
>  typedef u16 layer_mask_t;
>  /* Makes sure all layers can be checked. */
> @@ -84,6 +87,11 @@ enum landlock_key_type {
>  	 * keys.
>  	 */
>  	LANDLOCK_KEY_INODE = 1,
> +	/**
> +	 * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's
> +	 * node keys.
> +	 */
> +	LANDLOCK_KEY_NET_PORT = 2,

You don't need to specify "2".


> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
> index 8a54e87dbb17..da6cbd0032ca 100644
> --- a/security/landlock/syscalls.c
> +++ b/security/landlock/syscalls.c
> @@ -29,6 +29,7 @@
>  #include "cred.h"
>  #include "fs.h"
>  #include "limits.h"
> +#include "net.h"
>  #include "ruleset.h"
>  #include "setup.h"
> 
> @@ -74,7 +75,8 @@ static void build_check_abi(void)
>  {
>  	struct landlock_ruleset_attr ruleset_attr;
>  	struct landlock_path_beneath_attr path_beneath_attr;
> -	size_t ruleset_size, path_beneath_size;
> +	struct landlock_net_port_attr net_port_attr;
> +	size_t ruleset_size, path_beneath_size, net_service_size;

net_port_size

Mickaël Salaün Oct. 9, 2023, 2:12 p.m. UTC | #2

On Mon, Oct 02, 2023 at 10:26:36PM +0200, Mickaël Salaün wrote:
> Thanks for this new version Konstantin. I pushed this series, with minor
> changes, to -next. So far, no warning. But it needs some changes, mostly
> kernel-only, but also one with the handling of port 0 with bind (see my
> review below).
> 
> On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
> > This commit adds network rules support in the ruleset management
> > helpers and the landlock_create_ruleset syscall.
> > Refactor user space API to support network actions. Add new network
> > access flags, network rule and network attributes. Increment Landlock
> > ABI version. Expand access_masks_t to u32 to be sure network access
> > rights can be stored. Implement socket_bind() and socket_connect()
> > LSM hooks, which enables to restrict TCP socket binding and connection
> > to specific ports.
> > The new landlock_net_port_attr structure has two fields. The allowed_access
> > field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
> > the port value according to the allowed protocol. This field can
> > take up to a 64-bit value [1] but the maximum value depends on the related
> > protocol (e.g. 16-bit for TCP).
> > 
> > [1]
> > https://lore.kernel.org/r/[e-mail]
> > 
> > Signed-off-by: Mickaël Salaün <[e-mail]>
> > Signed-off-by: Konstantin Meskhidze <[e-mail]>
> > ---
> > 
> > Changes since v11:
> > * Replace dates with "2022-2023" in net.c/h files headers.
> > * Removes WARN_ON_ONCE(!domain) in check_socket_access().
> > * Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family).
> > * Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT.
> > * Renames landlock_net_service_attr to landlock_net_port_attr.
> > * Defines two add_rule_net_service() functions according to
> >   IS_ENABLED(CONFIG_INET) instead of changing the body of the only
> >   function.
> > * Adds af_family consistency check while handling AF_UNSPEC specifically.
> > * Adds bind_access_mask in add_rule_net_service() to deny all rules with bind
> >   action on port zero.
> > * Minor fixes.
> > * Refactors commit message.
> > 
> > Changes since v10:
> > * Removes "packed" attribute.
> > * Applies Mickaёl's patch with some refactoring.
> > * Deletes get_port() and check_addrlen() helpers.
> > * Refactors check_socket_access() by squashing get_port() and
> >   check_addrlen() helpers into it.
> > * Fixes commit message.
> > 
> > Changes since v9:
> > * Changes UAPI port field to __u64.
> > * Moves shared code into check_socket_access().
> > * Adds get_raw_handled_net_accesses() and
> >   get_current_net_domain() helpers.
> > * Minor fixes.
> > 
> > Changes since v8:
> > * Squashes commits.
> > * Refactors commit message.
> > * Changes UAPI port field to __be16.
> > * Changes logic of bind/connect hooks with AF_UNSPEC families.
> > * Adds address length checking.
> > * Minor fixes.
> > 
> > Changes since v7:
> > * Squashes commits.
> > * Increments ABI version to 4.
> > * Refactors commit message.
> > * Minor fixes.
> > 
> > Changes since v6:
> > * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
> >   because it OR values.
> > * Makes landlock_add_net_access_mask() more resilient incorrect values.
> > * Refactors landlock_get_net_access_mask().
> > * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
> >   LANDLOCK_NUM_ACCESS_FS as value.
> > * Updates access_masks_t to u32 to support network access actions.
> > * Refactors landlock internal functions to support network actions with
> >   landlock_key/key_type/id types.
> > 
> > Changes since v5:
> > * Gets rid of partial revert from landlock_add_rule
> > syscall.
> > * Formats code with clang-format-14.
> > 
> > Changes since v4:
> > * Refactors landlock_create_ruleset() - splits ruleset and
> > masks checks.
> > * Refactors landlock_create_ruleset() and landlock mask
> > setters/getters to support two rule types.
> > * Refactors landlock_add_rule syscall add_rule_path_beneath
> > function by factoring out get_ruleset_from_fd() and
> > landlock_put_ruleset().
> > 
> > Changes since v3:
> > * Splits commit.
> > * Adds network rule support for internal landlock functions.
> > * Adds set_mask and get_mask for network.
> > * Adds rb_root root_net_port.
> > 
> > ---
> >  include/uapi/linux/landlock.h                |  47 ++++
> >  security/landlock/Kconfig                    |   3 +-
> >  security/landlock/Makefile                   |   2 +
> >  security/landlock/limits.h                   |   5 +
> >  security/landlock/net.c                      | 241 +++++++++++++++++++
> >  security/landlock/net.h                      |  35 +++
> >  security/landlock/ruleset.c                  |  62 ++++-
> >  security/landlock/ruleset.h                  |  59 ++++-
> >  security/landlock/setup.c                    |   2 +
> >  security/landlock/syscalls.c                 |  33 ++-
> >  tools/testing/selftests/landlock/base_test.c |   2 +-
> >  11 files changed, 467 insertions(+), 24 deletions(-)
> >  create mode 100644 security/landlock/net.c
> >  create mode 100644 security/landlock/net.h
> > 

> > diff --git a/security/landlock/net.c b/security/landlock/net.c
> > new file mode 100644
> > index 000000000000..62b830653e25
> > --- /dev/null
> > +++ b/security/landlock/net.c
> > @@ -0,0 +1,241 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Landlock LSM - Network management and hooks
> > + *
> > + * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
> > + * Copyright © 2022-2023 Microsoft Corporation
> > + */
> > +
> > +#include <linux/in.h>
> > +#include <linux/net.h>
> > +#include <linux/socket.h>
> > +#include <net/ipv6.h>
> > +
> > +#include "common.h"
> > +#include "cred.h"
> > +#include "limits.h"
> > +#include "net.h"
> > +#include "ruleset.h"
> > +
> > +int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
> > +			     const u16 port, access_mask_t access_rights)
> 
> This function is only used in add_rule_net_service(), so it should not
> be exported, and we can merge it (into landlock_add_rule_net_port).
> 
> > +{
> > +	int err;
> > +	const struct landlock_id id = {
> > +		.key.data = (__force uintptr_t)htons(port),
> > +		.type = LANDLOCK_KEY_NET_PORT,
> > +	};
> > +
> > +	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
> > +
> > +	/* Transforms relative access rights to absolute ones. */
> > +	access_rights |= LANDLOCK_MASK_ACCESS_NET &
> > +			 ~landlock_get_net_access_mask(ruleset, 0);
> > +
> > +	mutex_lock(&ruleset->lock);
> > +	err = landlock_insert_rule(ruleset, id, access_rights);
> > +	mutex_unlock(&ruleset->lock);
> > +
> > +	return err;
> > +}
> > +
> > +int add_rule_net_service(struct landlock_ruleset *ruleset,
> 
> We should only export functions with a "landlock_" prefix, and "service"
> is now replaced with "port", which gives landlock_add_rule_net_port().
> 
> For consistency, we should also rename add_rule_path_beneath() into
> landlock_add_rule_path_beneath(), move it into fs.c, and merge
> landlock_append_fs_rule() into it (being careful to not move the related
> code to ease review). This change should be part of the "landlock:
> Refactor landlock_add_rule() syscall" patch. Please be careful to keep
> the other changes happening in other patches.
> 
> 
> > +			 const void __user *const rule_attr)
> > +{
> > +	struct landlock_net_port_attr net_port_attr;
> > +	int res;
> > +	access_mask_t mask, bind_access_mask;
> > +
> > +	/* Copies raw user space buffer. */
> > +	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
> 
> We should include <linux/uaccess.h> because of copy_from_user().
> 
> Same for landlock_add_rule_path_beneath().
> 
> > +	if (res)
> > +		return -EFAULT;
> > +
> > +	/*
> > +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
> > +	 * are ignored by network actions.
> > +	 */
> > +	if (!net_port_attr.allowed_access)
> > +		return -ENOMSG;
> > +
> > +	/*
> > +	 * Checks that allowed_access matches the @ruleset constraints
> > +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
> > +	 */
> > +	mask = landlock_get_net_access_mask(ruleset, 0);
> > +	if ((net_port_attr.allowed_access | mask) != mask)
> > +		return -EINVAL;
> > +
> > +	/*
> > +	 * Denies inserting a rule with port 0 (for bind action) or
> > +	 * higher than 65535.
> > +	 */
> > +	bind_access_mask = net_port_attr.allowed_access &
> > +			   LANDLOCK_ACCESS_NET_BIND_TCP;
> > +	if (((net_port_attr.port == 0) &&
> > +	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||
> > +	    (net_port_attr.port > U16_MAX))
> > +		return -EINVAL;
> > +
> > +	/* Imports the new rule. */
> > +	return landlock_append_net_rule(ruleset, net_port_attr.port,
> > +					net_port_attr.allowed_access);
> > +}

Please ignore the above suggestions. Thinking more about this, let's
keep the static add_rule_net_service() in syscalls.c, and only make the
inline landlock_add_rule_net_service() return -EAFNOSUPPORT (which is
already the case with this patch when CONFIG_INET is not set). This will
slightly change the current semantic but enable to check all the
syscalls arguments even if CONFIG_INET is not set, which is a good thing
(and should be reflected in tests). It is better to group all the code
handling user space memory copying and ABI specificities in the
syscalls.c file. This approach is simpler, it will avoid the exported
function issues (e.g. add_rule_net_service), and it will not require
more changes to the fs.[ch] files.

Mickaël Salaün Oct. 9, 2023, 2:13 p.m. UTC | #3

On Mon, Oct 09, 2023 at 04:12:42PM +0200, Mickaël Salaün wrote:
> On Mon, Oct 02, 2023 at 10:26:36PM +0200, Mickaël Salaün wrote:
> > Thanks for this new version Konstantin. I pushed this series, with minor
> > changes, to -next. So far, no warning. But it needs some changes, mostly
> > kernel-only, but also one with the handling of port 0 with bind (see my
> > review below).
> > 
> > On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
> > > This commit adds network rules support in the ruleset management
> > > helpers and the landlock_create_ruleset syscall.
> > > Refactor user space API to support network actions. Add new network
> > > access flags, network rule and network attributes. Increment Landlock
> > > ABI version. Expand access_masks_t to u32 to be sure network access
> > > rights can be stored. Implement socket_bind() and socket_connect()
> > > LSM hooks, which enables to restrict TCP socket binding and connection
> > > to specific ports.
> > > The new landlock_net_port_attr structure has two fields. The allowed_access
> > > field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
> > > the port value according to the allowed protocol. This field can
> > > take up to a 64-bit value [1] but the maximum value depends on the related
> > > protocol (e.g. 16-bit for TCP).
> > > 
> > > [1]
> > > https://lore.kernel.org/r/[e-mail]
> > > 
> > > Signed-off-by: Mickaël Salaün <[e-mail]>
> > > Signed-off-by: Konstantin Meskhidze <[e-mail]>
> > > ---
> > > 
> > > Changes since v11:
> > > * Replace dates with "2022-2023" in net.c/h files headers.
> > > * Removes WARN_ON_ONCE(!domain) in check_socket_access().
> > > * Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family).
> > > * Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT.
> > > * Renames landlock_net_service_attr to landlock_net_port_attr.
> > > * Defines two add_rule_net_service() functions according to
> > >   IS_ENABLED(CONFIG_INET) instead of changing the body of the only
> > >   function.
> > > * Adds af_family consistency check while handling AF_UNSPEC specifically.
> > > * Adds bind_access_mask in add_rule_net_service() to deny all rules with bind
> > >   action on port zero.
> > > * Minor fixes.
> > > * Refactors commit message.
> > > 
> > > Changes since v10:
> > > * Removes "packed" attribute.
> > > * Applies Mickaёl's patch with some refactoring.
> > > * Deletes get_port() and check_addrlen() helpers.
> > > * Refactors check_socket_access() by squashing get_port() and
> > >   check_addrlen() helpers into it.
> > > * Fixes commit message.
> > > 
> > > Changes since v9:
> > > * Changes UAPI port field to __u64.
> > > * Moves shared code into check_socket_access().
> > > * Adds get_raw_handled_net_accesses() and
> > >   get_current_net_domain() helpers.
> > > * Minor fixes.
> > > 
> > > Changes since v8:
> > > * Squashes commits.
> > > * Refactors commit message.
> > > * Changes UAPI port field to __be16.
> > > * Changes logic of bind/connect hooks with AF_UNSPEC families.
> > > * Adds address length checking.
> > > * Minor fixes.
> > > 
> > > Changes since v7:
> > > * Squashes commits.
> > > * Increments ABI version to 4.
> > > * Refactors commit message.
> > > * Minor fixes.
> > > 
> > > Changes since v6:
> > > * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
> > >   because it OR values.
> > > * Makes landlock_add_net_access_mask() more resilient incorrect values.
> > > * Refactors landlock_get_net_access_mask().
> > > * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
> > >   LANDLOCK_NUM_ACCESS_FS as value.
> > > * Updates access_masks_t to u32 to support network access actions.
> > > * Refactors landlock internal functions to support network actions with
> > >   landlock_key/key_type/id types.
> > > 
> > > Changes since v5:
> > > * Gets rid of partial revert from landlock_add_rule
> > > syscall.
> > > * Formats code with clang-format-14.
> > > 
> > > Changes since v4:
> > > * Refactors landlock_create_ruleset() - splits ruleset and
> > > masks checks.
> > > * Refactors landlock_create_ruleset() and landlock mask
> > > setters/getters to support two rule types.
> > > * Refactors landlock_add_rule syscall add_rule_path_beneath
> > > function by factoring out get_ruleset_from_fd() and
> > > landlock_put_ruleset().
> > > 
> > > Changes since v3:
> > > * Splits commit.
> > > * Adds network rule support for internal landlock functions.
> > > * Adds set_mask and get_mask for network.
> > > * Adds rb_root root_net_port.
> > > 
> > > ---
> > >  include/uapi/linux/landlock.h                |  47 ++++
> > >  security/landlock/Kconfig                    |   3 +-
> > >  security/landlock/Makefile                   |   2 +
> > >  security/landlock/limits.h                   |   5 +
> > >  security/landlock/net.c                      | 241 +++++++++++++++++++
> > >  security/landlock/net.h                      |  35 +++
> > >  security/landlock/ruleset.c                  |  62 ++++-
> > >  security/landlock/ruleset.h                  |  59 ++++-
> > >  security/landlock/setup.c                    |   2 +
> > >  security/landlock/syscalls.c                 |  33 ++-
> > >  tools/testing/selftests/landlock/base_test.c |   2 +-
> > >  11 files changed, 467 insertions(+), 24 deletions(-)
> > >  create mode 100644 security/landlock/net.c
> > >  create mode 100644 security/landlock/net.h
> > > 
> 
> > > diff --git a/security/landlock/net.c b/security/landlock/net.c
> > > new file mode 100644
> > > index 000000000000..62b830653e25
> > > --- /dev/null
> > > +++ b/security/landlock/net.c
> > > @@ -0,0 +1,241 @@
> > > +// SPDX-License-Identifier: GPL-2.0-only
> > > +/*
> > > + * Landlock LSM - Network management and hooks
> > > + *
> > > + * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
> > > + * Copyright © 2022-2023 Microsoft Corporation
> > > + */
> > > +
> > > +#include <linux/in.h>
> > > +#include <linux/net.h>
> > > +#include <linux/socket.h>
> > > +#include <net/ipv6.h>
> > > +
> > > +#include "common.h"
> > > +#include "cred.h"
> > > +#include "limits.h"
> > > +#include "net.h"
> > > +#include "ruleset.h"
> > > +
> > > +int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
> > > +			     const u16 port, access_mask_t access_rights)
> > 
> > This function is only used in add_rule_net_service(), so it should not
> > be exported, and we can merge it (into landlock_add_rule_net_port).
> > 
> > > +{
> > > +	int err;
> > > +	const struct landlock_id id = {
> > > +		.key.data = (__force uintptr_t)htons(port),
> > > +		.type = LANDLOCK_KEY_NET_PORT,
> > > +	};
> > > +
> > > +	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
> > > +
> > > +	/* Transforms relative access rights to absolute ones. */
> > > +	access_rights |= LANDLOCK_MASK_ACCESS_NET &
> > > +			 ~landlock_get_net_access_mask(ruleset, 0);
> > > +
> > > +	mutex_lock(&ruleset->lock);
> > > +	err = landlock_insert_rule(ruleset, id, access_rights);
> > > +	mutex_unlock(&ruleset->lock);
> > > +
> > > +	return err;
> > > +}
> > > +
> > > +int add_rule_net_service(struct landlock_ruleset *ruleset,
> > 
> > We should only export functions with a "landlock_" prefix, and "service"
> > is now replaced with "port", which gives landlock_add_rule_net_port().
> > 
> > For consistency, we should also rename add_rule_path_beneath() into
> > landlock_add_rule_path_beneath(), move it into fs.c, and merge
> > landlock_append_fs_rule() into it (being careful to not move the related
> > code to ease review). This change should be part of the "landlock:
> > Refactor landlock_add_rule() syscall" patch. Please be careful to keep
> > the other changes happening in other patches.
> > 
> > 
> > > +			 const void __user *const rule_attr)
> > > +{
> > > +	struct landlock_net_port_attr net_port_attr;
> > > +	int res;
> > > +	access_mask_t mask, bind_access_mask;
> > > +
> > > +	/* Copies raw user space buffer. */
> > > +	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
> > 
> > We should include <linux/uaccess.h> because of copy_from_user().
> > 
> > Same for landlock_add_rule_path_beneath().
> > 
> > > +	if (res)
> > > +		return -EFAULT;
> > > +
> > > +	/*
> > > +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
> > > +	 * are ignored by network actions.
> > > +	 */
> > > +	if (!net_port_attr.allowed_access)
> > > +		return -ENOMSG;
> > > +
> > > +	/*
> > > +	 * Checks that allowed_access matches the @ruleset constraints
> > > +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
> > > +	 */
> > > +	mask = landlock_get_net_access_mask(ruleset, 0);
> > > +	if ((net_port_attr.allowed_access | mask) != mask)
> > > +		return -EINVAL;
> > > +
> > > +	/*
> > > +	 * Denies inserting a rule with port 0 (for bind action) or
> > > +	 * higher than 65535.
> > > +	 */
> > > +	bind_access_mask = net_port_attr.allowed_access &
> > > +			   LANDLOCK_ACCESS_NET_BIND_TCP;
> > > +	if (((net_port_attr.port == 0) &&
> > > +	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||
> > > +	    (net_port_attr.port > U16_MAX))
> > > +		return -EINVAL;
> > > +
> > > +	/* Imports the new rule. */
> > > +	return landlock_append_net_rule(ruleset, net_port_attr.port,
> > > +					net_port_attr.allowed_access);
> > > +}
> 
> Please ignore the above suggestions. Thinking more about this, let's
> keep the static add_rule_net_service() in syscalls.c, and only make the
> inline landlock_add_rule_net_service() return -EAFNOSUPPORT (which is

"inline landlock_append_net_rule()" of course

> already the case with this patch when CONFIG_INET is not set). This will
> slightly change the current semantic but enable to check all the
> syscalls arguments even if CONFIG_INET is not set, which is a good thing
> (and should be reflected in tests). It is better to group all the code
> handling user space memory copying and ABI specificities in the
> syscalls.c file. This approach is simpler, it will avoid the exported
> function issues (e.g. add_rule_net_service), and it will not require
> more changes to the fs.[ch] files.

Mickaël Salaün Oct. 9, 2023, 3:36 p.m. UTC | #4

On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
> This commit adds network rules support in the ruleset management
> helpers and the landlock_create_ruleset syscall.
> Refactor user space API to support network actions. Add new network
> access flags, network rule and network attributes. Increment Landlock
> ABI version. Expand access_masks_t to u32 to be sure network access
> rights can be stored. Implement socket_bind() and socket_connect()
> LSM hooks, which enables to restrict TCP socket binding and connection
> to specific ports.
> The new landlock_net_port_attr structure has two fields. The allowed_access
> field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
> the port value according to the allowed protocol. This field can
> take up to a 64-bit value [1] but the maximum value depends on the related
> protocol (e.g. 16-bit for TCP).
> 
> [1]
> https://lore.kernel.org/r/[e-mail]

Could you please include here the rationale to not tie access rights to
sockets' file descriptor, and link [2]?

[2] https://lore.kernel.org/r/[e-mail]

Konstantin Meskhidze (A) Oct. 10, 2023, 2:20 a.m. UTC | #5

10/9/2023 5:12 PM, Mickaël Salaün пишет:
> On Mon, Oct 02, 2023 at 10:26:36PM +0200, Mickaël Salaün wrote:
>> Thanks for this new version Konstantin. I pushed this series, with minor
>> changes, to -next. So far, no warning. But it needs some changes, mostly
>> kernel-only, but also one with the handling of port 0 with bind (see my
>> review below).
>> 
>> On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
>> > This commit adds network rules support in the ruleset management
>> > helpers and the landlock_create_ruleset syscall.
>> > Refactor user space API to support network actions. Add new network
>> > access flags, network rule and network attributes. Increment Landlock
>> > ABI version. Expand access_masks_t to u32 to be sure network access
>> > rights can be stored. Implement socket_bind() and socket_connect()
>> > LSM hooks, which enables to restrict TCP socket binding and connection
>> > to specific ports.
>> > The new landlock_net_port_attr structure has two fields. The allowed_access
>> > field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
>> > the port value according to the allowed protocol. This field can
>> > take up to a 64-bit value [1] but the maximum value depends on the related
>> > protocol (e.g. 16-bit for TCP).
>> > 
>> > [1]
>> > https://lore.kernel.org/r/[e-mail]
>> > 
>> > Signed-off-by: Mickaël Salaün <[e-mail]>
>> > Signed-off-by: Konstantin Meskhidze <[e-mail]>
>> > ---
>> > 
>> > Changes since v11:
>> > * Replace dates with "2022-2023" in net.c/h files headers.
>> > * Removes WARN_ON_ONCE(!domain) in check_socket_access().
>> > * Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family).
>> > * Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT.
>> > * Renames landlock_net_service_attr to landlock_net_port_attr.
>> > * Defines two add_rule_net_service() functions according to
>> >   IS_ENABLED(CONFIG_INET) instead of changing the body of the only
>> >   function.
>> > * Adds af_family consistency check while handling AF_UNSPEC specifically.
>> > * Adds bind_access_mask in add_rule_net_service() to deny all rules with bind
>> >   action on port zero.
>> > * Minor fixes.
>> > * Refactors commit message.
>> > 
>> > Changes since v10:
>> > * Removes "packed" attribute.
>> > * Applies Mickaёl's patch with some refactoring.
>> > * Deletes get_port() and check_addrlen() helpers.
>> > * Refactors check_socket_access() by squashing get_port() and
>> >   check_addrlen() helpers into it.
>> > * Fixes commit message.
>> > 
>> > Changes since v9:
>> > * Changes UAPI port field to __u64.
>> > * Moves shared code into check_socket_access().
>> > * Adds get_raw_handled_net_accesses() and
>> >   get_current_net_domain() helpers.
>> > * Minor fixes.
>> > 
>> > Changes since v8:
>> > * Squashes commits.
>> > * Refactors commit message.
>> > * Changes UAPI port field to __be16.
>> > * Changes logic of bind/connect hooks with AF_UNSPEC families.
>> > * Adds address length checking.
>> > * Minor fixes.
>> > 
>> > Changes since v7:
>> > * Squashes commits.
>> > * Increments ABI version to 4.
>> > * Refactors commit message.
>> > * Minor fixes.
>> > 
>> > Changes since v6:
>> > * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
>> >   because it OR values.
>> > * Makes landlock_add_net_access_mask() more resilient incorrect values.
>> > * Refactors landlock_get_net_access_mask().
>> > * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
>> >   LANDLOCK_NUM_ACCESS_FS as value.
>> > * Updates access_masks_t to u32 to support network access actions.
>> > * Refactors landlock internal functions to support network actions with
>> >   landlock_key/key_type/id types.
>> > 
>> > Changes since v5:
>> > * Gets rid of partial revert from landlock_add_rule
>> > syscall.
>> > * Formats code with clang-format-14.
>> > 
>> > Changes since v4:
>> > * Refactors landlock_create_ruleset() - splits ruleset and
>> > masks checks.
>> > * Refactors landlock_create_ruleset() and landlock mask
>> > setters/getters to support two rule types.
>> > * Refactors landlock_add_rule syscall add_rule_path_beneath
>> > function by factoring out get_ruleset_from_fd() and
>> > landlock_put_ruleset().
>> > 
>> > Changes since v3:
>> > * Splits commit.
>> > * Adds network rule support for internal landlock functions.
>> > * Adds set_mask and get_mask for network.
>> > * Adds rb_root root_net_port.
>> > 
>> > ---
>> >  include/uapi/linux/landlock.h                |  47 ++++
>> >  security/landlock/Kconfig                    |   3 +-
>> >  security/landlock/Makefile                   |   2 +
>> >  security/landlock/limits.h                   |   5 +
>> >  security/landlock/net.c                      | 241 +++++++++++++++++++
>> >  security/landlock/net.h                      |  35 +++
>> >  security/landlock/ruleset.c                  |  62 ++++-
>> >  security/landlock/ruleset.h                  |  59 ++++-
>> >  security/landlock/setup.c                    |   2 +
>> >  security/landlock/syscalls.c                 |  33 ++-
>> >  tools/testing/selftests/landlock/base_test.c |   2 +-
>> >  11 files changed, 467 insertions(+), 24 deletions(-)
>> >  create mode 100644 security/landlock/net.c
>> >  create mode 100644 security/landlock/net.h
>> > 
> 
>> > diff --git a/security/landlock/net.c b/security/landlock/net.c
>> > new file mode 100644
>> > index 000000000000..62b830653e25
>> > --- /dev/null
>> > +++ b/security/landlock/net.c
>> > @@ -0,0 +1,241 @@
>> > +// SPDX-License-Identifier: GPL-2.0-only
>> > +/*
>> > + * Landlock LSM - Network management and hooks
>> > + *
>> > + * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
>> > + * Copyright © 2022-2023 Microsoft Corporation
>> > + */
>> > +
>> > +#include <linux/in.h>
>> > +#include <linux/net.h>
>> > +#include <linux/socket.h>
>> > +#include <net/ipv6.h>
>> > +
>> > +#include "common.h"
>> > +#include "cred.h"
>> > +#include "limits.h"
>> > +#include "net.h"
>> > +#include "ruleset.h"
>> > +
>> > +int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
>> > +			     const u16 port, access_mask_t access_rights)
>> 
>> This function is only used in add_rule_net_service(), so it should not
>> be exported, and we can merge it (into landlock_add_rule_net_port).
>> 
>> > +{
>> > +	int err;
>> > +	const struct landlock_id id = {
>> > +		.key.data = (__force uintptr_t)htons(port),
>> > +		.type = LANDLOCK_KEY_NET_PORT,
>> > +	};
>> > +
>> > +	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
>> > +
>> > +	/* Transforms relative access rights to absolute ones. */
>> > +	access_rights |= LANDLOCK_MASK_ACCESS_NET &
>> > +			 ~landlock_get_net_access_mask(ruleset, 0);
>> > +
>> > +	mutex_lock(&ruleset->lock);
>> > +	err = landlock_insert_rule(ruleset, id, access_rights);
>> > +	mutex_unlock(&ruleset->lock);
>> > +
>> > +	return err;
>> > +}
>> > +
>> > +int add_rule_net_service(struct landlock_ruleset *ruleset,
>> 
>> We should only export functions with a "landlock_" prefix, and "service"
>> is now replaced with "port", which gives landlock_add_rule_net_port().
>> 
>> For consistency, we should also rename add_rule_path_beneath() into
>> landlock_add_rule_path_beneath(), move it into fs.c, and merge
>> landlock_append_fs_rule() into it (being careful to not move the related
>> code to ease review). This change should be part of the "landlock:
>> Refactor landlock_add_rule() syscall" patch. Please be careful to keep
>> the other changes happening in other patches.
>> 
>> 
>> > +			 const void __user *const rule_attr)
>> > +{
>> > +	struct landlock_net_port_attr net_port_attr;
>> > +	int res;
>> > +	access_mask_t mask, bind_access_mask;
>> > +
>> > +	/* Copies raw user space buffer. */
>> > +	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
>> 
>> We should include <linux/uaccess.h> because of copy_from_user().
>> 
>> Same for landlock_add_rule_path_beneath().
>> 
>> > +	if (res)
>> > +		return -EFAULT;
>> > +
>> > +	/*
>> > +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
>> > +	 * are ignored by network actions.
>> > +	 */
>> > +	if (!net_port_attr.allowed_access)
>> > +		return -ENOMSG;
>> > +
>> > +	/*
>> > +	 * Checks that allowed_access matches the @ruleset constraints
>> > +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
>> > +	 */
>> > +	mask = landlock_get_net_access_mask(ruleset, 0);
>> > +	if ((net_port_attr.allowed_access | mask) != mask)
>> > +		return -EINVAL;
>> > +
>> > +	/*
>> > +	 * Denies inserting a rule with port 0 (for bind action) or
>> > +	 * higher than 65535.
>> > +	 */
>> > +	bind_access_mask = net_port_attr.allowed_access &
>> > +			   LANDLOCK_ACCESS_NET_BIND_TCP;
>> > +	if (((net_port_attr.port == 0) &&
>> > +	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||
>> > +	    (net_port_attr.port > U16_MAX))
>> > +		return -EINVAL;
>> > +
>> > +	/* Imports the new rule. */
>> > +	return landlock_append_net_rule(ruleset, net_port_attr.port,
>> > +					net_port_attr.allowed_access);
>> > +}
> 
> Please ignore the above suggestions. Thinking more about this, let's
> keep the static add_rule_net_service() in syscalls.c, and only make the
> inline landlock_add_rule_net_service() return -EAFNOSUPPORT (which is
> already the case with this patch when CONFIG_INET is not set). This will
> slightly change the current semantic but enable to check all the
> syscalls arguments even if CONFIG_INET is not set, which is a good thing
> (and should be reflected in tests). It is better to group all the code
> handling user space memory copying and ABI specificities in the
> syscalls.c file. This approach is simpler, it will avoid the exported
> function issues (e.g. add_rule_net_service), and it will not require
> more changes to the fs.[ch] files.
> .
   Ok.Will be moved back to syscalls.c.
   What about renaming to add_rule_net_service()->add_rule_net_port() ???

Konstantin Meskhidze (A) Oct. 10, 2023, 2:23 a.m. UTC | #6

10/9/2023 5:13 PM, Mickaël Salaün пишет:
> On Mon, Oct 09, 2023 at 04:12:42PM +0200, Mickaël Salaün wrote:
>> On Mon, Oct 02, 2023 at 10:26:36PM +0200, Mickaël Salaün wrote:
>> > Thanks for this new version Konstantin. I pushed this series, with minor
>> > changes, to -next. So far, no warning. But it needs some changes, mostly
>> > kernel-only, but also one with the handling of port 0 with bind (see my
>> > review below).
>> > 
>> > On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
>> > > This commit adds network rules support in the ruleset management
>> > > helpers and the landlock_create_ruleset syscall.
>> > > Refactor user space API to support network actions. Add new network
>> > > access flags, network rule and network attributes. Increment Landlock
>> > > ABI version. Expand access_masks_t to u32 to be sure network access
>> > > rights can be stored. Implement socket_bind() and socket_connect()
>> > > LSM hooks, which enables to restrict TCP socket binding and connection
>> > > to specific ports.
>> > > The new landlock_net_port_attr structure has two fields. The allowed_access
>> > > field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
>> > > the port value according to the allowed protocol. This field can
>> > > take up to a 64-bit value [1] but the maximum value depends on the related
>> > > protocol (e.g. 16-bit for TCP).
>> > > 
>> > > [1]
>> > > https://lore.kernel.org/r/[e-mail]
>> > > 
>> > > Signed-off-by: Mickaël Salaün <[e-mail]>
>> > > Signed-off-by: Konstantin Meskhidze <[e-mail]>
>> > > ---
>> > > 
>> > > Changes since v11:
>> > > * Replace dates with "2022-2023" in net.c/h files headers.
>> > > * Removes WARN_ON_ONCE(!domain) in check_socket_access().
>> > > * Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family).
>> > > * Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT.
>> > > * Renames landlock_net_service_attr to landlock_net_port_attr.
>> > > * Defines two add_rule_net_service() functions according to
>> > >   IS_ENABLED(CONFIG_INET) instead of changing the body of the only
>> > >   function.
>> > > * Adds af_family consistency check while handling AF_UNSPEC specifically.
>> > > * Adds bind_access_mask in add_rule_net_service() to deny all rules with bind
>> > >   action on port zero.
>> > > * Minor fixes.
>> > > * Refactors commit message.
>> > > 
>> > > Changes since v10:
>> > > * Removes "packed" attribute.
>> > > * Applies Mickaёl's patch with some refactoring.
>> > > * Deletes get_port() and check_addrlen() helpers.
>> > > * Refactors check_socket_access() by squashing get_port() and
>> > >   check_addrlen() helpers into it.
>> > > * Fixes commit message.
>> > > 
>> > > Changes since v9:
>> > > * Changes UAPI port field to __u64.
>> > > * Moves shared code into check_socket_access().
>> > > * Adds get_raw_handled_net_accesses() and
>> > >   get_current_net_domain() helpers.
>> > > * Minor fixes.
>> > > 
>> > > Changes since v8:
>> > > * Squashes commits.
>> > > * Refactors commit message.
>> > > * Changes UAPI port field to __be16.
>> > > * Changes logic of bind/connect hooks with AF_UNSPEC families.
>> > > * Adds address length checking.
>> > > * Minor fixes.
>> > > 
>> > > Changes since v7:
>> > > * Squashes commits.
>> > > * Increments ABI version to 4.
>> > > * Refactors commit message.
>> > > * Minor fixes.
>> > > 
>> > > Changes since v6:
>> > > * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
>> > >   because it OR values.
>> > > * Makes landlock_add_net_access_mask() more resilient incorrect values.
>> > > * Refactors landlock_get_net_access_mask().
>> > > * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
>> > >   LANDLOCK_NUM_ACCESS_FS as value.
>> > > * Updates access_masks_t to u32 to support network access actions.
>> > > * Refactors landlock internal functions to support network actions with
>> > >   landlock_key/key_type/id types.
>> > > 
>> > > Changes since v5:
>> > > * Gets rid of partial revert from landlock_add_rule
>> > > syscall.
>> > > * Formats code with clang-format-14.
>> > > 
>> > > Changes since v4:
>> > > * Refactors landlock_create_ruleset() - splits ruleset and
>> > > masks checks.
>> > > * Refactors landlock_create_ruleset() and landlock mask
>> > > setters/getters to support two rule types.
>> > > * Refactors landlock_add_rule syscall add_rule_path_beneath
>> > > function by factoring out get_ruleset_from_fd() and
>> > > landlock_put_ruleset().
>> > > 
>> > > Changes since v3:
>> > > * Splits commit.
>> > > * Adds network rule support for internal landlock functions.
>> > > * Adds set_mask and get_mask for network.
>> > > * Adds rb_root root_net_port.
>> > > 
>> > > ---
>> > >  include/uapi/linux/landlock.h                |  47 ++++
>> > >  security/landlock/Kconfig                    |   3 +-
>> > >  security/landlock/Makefile                   |   2 +
>> > >  security/landlock/limits.h                   |   5 +
>> > >  security/landlock/net.c                      | 241 +++++++++++++++++++
>> > >  security/landlock/net.h                      |  35 +++
>> > >  security/landlock/ruleset.c                  |  62 ++++-
>> > >  security/landlock/ruleset.h                  |  59 ++++-
>> > >  security/landlock/setup.c                    |   2 +
>> > >  security/landlock/syscalls.c                 |  33 ++-
>> > >  tools/testing/selftests/landlock/base_test.c |   2 +-
>> > >  11 files changed, 467 insertions(+), 24 deletions(-)
>> > >  create mode 100644 security/landlock/net.c
>> > >  create mode 100644 security/landlock/net.h
>> > > 
>> 
>> > > diff --git a/security/landlock/net.c b/security/landlock/net.c
>> > > new file mode 100644
>> > > index 000000000000..62b830653e25
>> > > --- /dev/null
>> > > +++ b/security/landlock/net.c
>> > > @@ -0,0 +1,241 @@
>> > > +// SPDX-License-Identifier: GPL-2.0-only
>> > > +/*
>> > > + * Landlock LSM - Network management and hooks
>> > > + *
>> > > + * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
>> > > + * Copyright © 2022-2023 Microsoft Corporation
>> > > + */
>> > > +
>> > > +#include <linux/in.h>
>> > > +#include <linux/net.h>
>> > > +#include <linux/socket.h>
>> > > +#include <net/ipv6.h>
>> > > +
>> > > +#include "common.h"
>> > > +#include "cred.h"
>> > > +#include "limits.h"
>> > > +#include "net.h"
>> > > +#include "ruleset.h"
>> > > +
>> > > +int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
>> > > +			     const u16 port, access_mask_t access_rights)
>> > 
>> > This function is only used in add_rule_net_service(), so it should not
>> > be exported, and we can merge it (into landlock_add_rule_net_port).
>> > 
>> > > +{
>> > > +	int err;
>> > > +	const struct landlock_id id = {
>> > > +		.key.data = (__force uintptr_t)htons(port),
>> > > +		.type = LANDLOCK_KEY_NET_PORT,
>> > > +	};
>> > > +
>> > > +	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
>> > > +
>> > > +	/* Transforms relative access rights to absolute ones. */
>> > > +	access_rights |= LANDLOCK_MASK_ACCESS_NET &
>> > > +			 ~landlock_get_net_access_mask(ruleset, 0);
>> > > +
>> > > +	mutex_lock(&ruleset->lock);
>> > > +	err = landlock_insert_rule(ruleset, id, access_rights);
>> > > +	mutex_unlock(&ruleset->lock);
>> > > +
>> > > +	return err;
>> > > +}
>> > > +
>> > > +int add_rule_net_service(struct landlock_ruleset *ruleset,
>> > 
>> > We should only export functions with a "landlock_" prefix, and "service"
>> > is now replaced with "port", which gives landlock_add_rule_net_port().
>> > 
>> > For consistency, we should also rename add_rule_path_beneath() into
>> > landlock_add_rule_path_beneath(), move it into fs.c, and merge
>> > landlock_append_fs_rule() into it (being careful to not move the related
>> > code to ease review). This change should be part of the "landlock:
>> > Refactor landlock_add_rule() syscall" patch. Please be careful to keep
>> > the other changes happening in other patches.
>> > 
>> > 
>> > > +			 const void __user *const rule_attr)
>> > > +{
>> > > +	struct landlock_net_port_attr net_port_attr;
>> > > +	int res;
>> > > +	access_mask_t mask, bind_access_mask;
>> > > +
>> > > +	/* Copies raw user space buffer. */
>> > > +	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
>> > 
>> > We should include <linux/uaccess.h> because of copy_from_user().
>> > 
>> > Same for landlock_add_rule_path_beneath().
>> > 
>> > > +	if (res)
>> > > +		return -EFAULT;
>> > > +
>> > > +	/*
>> > > +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
>> > > +	 * are ignored by network actions.
>> > > +	 */
>> > > +	if (!net_port_attr.allowed_access)
>> > > +		return -ENOMSG;
>> > > +
>> > > +	/*
>> > > +	 * Checks that allowed_access matches the @ruleset constraints
>> > > +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
>> > > +	 */
>> > > +	mask = landlock_get_net_access_mask(ruleset, 0);
>> > > +	if ((net_port_attr.allowed_access | mask) != mask)
>> > > +		return -EINVAL;
>> > > +
>> > > +	/*
>> > > +	 * Denies inserting a rule with port 0 (for bind action) or
>> > > +	 * higher than 65535.
>> > > +	 */
>> > > +	bind_access_mask = net_port_attr.allowed_access &
>> > > +			   LANDLOCK_ACCESS_NET_BIND_TCP;
>> > > +	if (((net_port_attr.port == 0) &&
>> > > +	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||
>> > > +	    (net_port_attr.port > U16_MAX))
>> > > +		return -EINVAL;
>> > > +
>> > > +	/* Imports the new rule. */
>> > > +	return landlock_append_net_rule(ruleset, net_port_attr.port,
>> > > +					net_port_attr.allowed_access);
>> > > +}
>> 
>> Please ignore the above suggestions. Thinking more about this, let's
>> keep the static add_rule_net_service() in syscalls.c, and only make the
>> inline landlock_add_rule_net_service() return -EAFNOSUPPORT (which is
> 
> "inline landlock_append_net_rule()" of course

    yep. got it.
> 
>> already the case with this patch when CONFIG_INET is not set). This will
>> slightly change the current semantic but enable to check all the
>> syscalls arguments even if CONFIG_INET is not set, which is a good thing
>> (and should be reflected in tests). It is better to group all the code
>> handling user space memory copying and ABI specificities in the
>> syscalls.c file. This approach is simpler, it will avoid the exported
>> function issues (e.g. add_rule_net_service), and it will not require
>> more changes to the fs.[ch] files.
> .

Konstantin Meskhidze (A) Oct. 10, 2023, 3:29 a.m. UTC | #7

10/2/2023 11:26 PM, Mickaël Salaün пишет:
> Thanks for this new version Konstantin. I pushed this series, with minor
> changes, to -next. So far, no warning. But it needs some changes, mostly
> kernel-only, but also one with the handling of port 0 with bind (see my
> review below).
> 
> On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
>> This commit adds network rules support in the ruleset management
>> helpers and the landlock_create_ruleset syscall.
>> Refactor user space API to support network actions. Add new network
>> access flags, network rule and network attributes. Increment Landlock
>> ABI version. Expand access_masks_t to u32 to be sure network access
>> rights can be stored. Implement socket_bind() and socket_connect()
>> LSM hooks, which enables to restrict TCP socket binding and connection
>> to specific ports.
>> The new landlock_net_port_attr structure has two fields. The allowed_access
>> field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
>> the port value according to the allowed protocol. This field can
>> take up to a 64-bit value [1] but the maximum value depends on the related
>> protocol (e.g. 16-bit for TCP).
>> 
>> [1]
>> https://lore.kernel.org/r/[e-mail]
>> 
>> Signed-off-by: Mickaël Salaün <[e-mail]>
>> Signed-off-by: Konstantin Meskhidze <[e-mail]>
>> ---
>> 
>> Changes since v11:
>> * Replace dates with "2022-2023" in net.c/h files headers.
>> * Removes WARN_ON_ONCE(!domain) in check_socket_access().
>> * Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family).
>> * Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT.
>> * Renames landlock_net_service_attr to landlock_net_port_attr.
>> * Defines two add_rule_net_service() functions according to
>>   IS_ENABLED(CONFIG_INET) instead of changing the body of the only
>>   function.
>> * Adds af_family consistency check while handling AF_UNSPEC specifically.
>> * Adds bind_access_mask in add_rule_net_service() to deny all rules with bind
>>   action on port zero.
>> * Minor fixes.
>> * Refactors commit message.
>> 
>> Changes since v10:
>> * Removes "packed" attribute.
>> * Applies Mickaёl's patch with some refactoring.
>> * Deletes get_port() and check_addrlen() helpers.
>> * Refactors check_socket_access() by squashing get_port() and
>>   check_addrlen() helpers into it.
>> * Fixes commit message.
>> 
>> Changes since v9:
>> * Changes UAPI port field to __u64.
>> * Moves shared code into check_socket_access().
>> * Adds get_raw_handled_net_accesses() and
>>   get_current_net_domain() helpers.
>> * Minor fixes.
>> 
>> Changes since v8:
>> * Squashes commits.
>> * Refactors commit message.
>> * Changes UAPI port field to __be16.
>> * Changes logic of bind/connect hooks with AF_UNSPEC families.
>> * Adds address length checking.
>> * Minor fixes.
>> 
>> Changes since v7:
>> * Squashes commits.
>> * Increments ABI version to 4.
>> * Refactors commit message.
>> * Minor fixes.
>> 
>> Changes since v6:
>> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
>>   because it OR values.
>> * Makes landlock_add_net_access_mask() more resilient incorrect values.
>> * Refactors landlock_get_net_access_mask().
>> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
>>   LANDLOCK_NUM_ACCESS_FS as value.
>> * Updates access_masks_t to u32 to support network access actions.
>> * Refactors landlock internal functions to support network actions with
>>   landlock_key/key_type/id types.
>> 
>> Changes since v5:
>> * Gets rid of partial revert from landlock_add_rule
>> syscall.
>> * Formats code with clang-format-14.
>> 
>> Changes since v4:
>> * Refactors landlock_create_ruleset() - splits ruleset and
>> masks checks.
>> * Refactors landlock_create_ruleset() and landlock mask
>> setters/getters to support two rule types.
>> * Refactors landlock_add_rule syscall add_rule_path_beneath
>> function by factoring out get_ruleset_from_fd() and
>> landlock_put_ruleset().
>> 
>> Changes since v3:
>> * Splits commit.
>> * Adds network rule support for internal landlock functions.
>> * Adds set_mask and get_mask for network.
>> * Adds rb_root root_net_port.
>> 
>> ---
>>  include/uapi/linux/landlock.h                |  47 ++++
>>  security/landlock/Kconfig                    |   3 +-
>>  security/landlock/Makefile                   |   2 +
>>  security/landlock/limits.h                   |   5 +
>>  security/landlock/net.c                      | 241 +++++++++++++++++++
>>  security/landlock/net.h                      |  35 +++
>>  security/landlock/ruleset.c                  |  62 ++++-
>>  security/landlock/ruleset.h                  |  59 ++++-
>>  security/landlock/setup.c                    |   2 +
>>  security/landlock/syscalls.c                 |  33 ++-
>>  tools/testing/selftests/landlock/base_test.c |   2 +-
>>  11 files changed, 467 insertions(+), 24 deletions(-)
>>  create mode 100644 security/landlock/net.c
>>  create mode 100644 security/landlock/net.h
>> 
>> diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
>> index 81d09ef9aa50..3b8400e8a4d9 100644
>> --- a/include/uapi/linux/landlock.h
>> +++ b/include/uapi/linux/landlock.h
>> @@ -31,6 +31,12 @@ struct landlock_ruleset_attr {
>>  	 * this access right.
>>  	 */
>>  	__u64 handled_access_fs;
>> +	/**
>> +	 * @handled_access_net: Bitmask of actions (cf. `Network flags`_)
>> +	 * that is handled by this ruleset and should then be forbidden if no
>> +	 * rule explicitly allow them.
>> +	 */
>> +	__u64 handled_access_net;
>>  };
>> 
>>  /*
>> @@ -54,6 +60,11 @@ enum landlock_rule_type {
>>  	 * landlock_path_beneath_attr .
>>  	 */
>>  	LANDLOCK_RULE_PATH_BENEATH = 1,
>> +	/**
>> +	 * @LANDLOCK_RULE_NET_PORT: Type of a &struct
>> +	 * landlock_net_port_attr .
>> +	 */
>> +	LANDLOCK_RULE_NET_PORT = 2,
>>  };
>> 
>>  /**
>> @@ -79,6 +90,23 @@ struct landlock_path_beneath_attr {
>>  	 */
>>  } __attribute__((packed));
>> 
>> +/**
>> + * struct landlock_net_port_attr - Network service definition
> 
> "Network port definition"

    Ok. Thanks.
> 
> 
>> diff --git a/security/landlock/Kconfig b/security/landlock/Kconfig
>> index c1e862a38410..10c099097533 100644
>> --- a/security/landlock/Kconfig
>> +++ b/security/landlock/Kconfig
>> @@ -2,7 +2,8 @@
>> 
>>  config SECURITY_LANDLOCK
>>  	bool "Landlock support"
>> -	depends on SECURITY
>> +	depends on SECURITY && !ARCH_EPHEMERAL_INODES
> 
> !ARCH_EPHEMERAL_INODES is definitely gone now.

   Ok. Got it.
> 
>> +	select SECURITY_NETWORK
>>  	select SECURITY_PATH
>>  	help
>>  	  Landlock is a sandboxing mechanism that enables processes to restrict
>> diff --git a/security/landlock/Makefile b/security/landlock/Makefile
>> index 7bbd2f413b3e..53d3c92ae22e 100644
>> --- a/security/landlock/Makefile
>> +++ b/security/landlock/Makefile
>> @@ -2,3 +2,5 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o
>> 
>>  landlock-y := setup.o syscalls.o object.o ruleset.o \
>>  	cred.o ptrace.o fs.o
>> +
>> +landlock-$(CONFIG_INET) += net.o
>> \ No newline at end of file
>> diff --git a/security/landlock/limits.h b/security/landlock/limits.h
>> index bafb3b8dc677..93c9c6f91556 100644
>> --- a/security/landlock/limits.h
>> +++ b/security/landlock/limits.h
>> @@ -23,6 +23,11 @@
>>  #define LANDLOCK_NUM_ACCESS_FS		__const_hweight64(LANDLOCK_MASK_ACCESS_FS)
>>  #define LANDLOCK_SHIFT_ACCESS_FS	0
>> 
>> +#define LANDLOCK_LAST_ACCESS_NET	LANDLOCK_ACCESS_NET_CONNECT_TCP
>> +#define LANDLOCK_MASK_ACCESS_NET	((LANDLOCK_LAST_ACCESS_NET << 1) - 1)
>> +#define LANDLOCK_NUM_ACCESS_NET		__const_hweight64(LANDLOCK_MASK_ACCESS_NET)
>> +#define LANDLOCK_SHIFT_ACCESS_NET	LANDLOCK_NUM_ACCESS_FS
>> +
>>  /* clang-format on */
>> 
>>  #endif /* _SECURITY_LANDLOCK_LIMITS_H */
>> diff --git a/security/landlock/net.c b/security/landlock/net.c
>> new file mode 100644
>> index 000000000000..62b830653e25
>> --- /dev/null
>> +++ b/security/landlock/net.c
>> @@ -0,0 +1,241 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Landlock LSM - Network management and hooks
>> + *
>> + * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
>> + * Copyright © 2022-2023 Microsoft Corporation
>> + */
>> +
>> +#include <linux/in.h>
>> +#include <linux/net.h>
>> +#include <linux/socket.h>
>> +#include <net/ipv6.h>
>> +
>> +#include "common.h"
>> +#include "cred.h"
>> +#include "limits.h"
>> +#include "net.h"
>> +#include "ruleset.h"
>> +
>> +int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
>> +			     const u16 port, access_mask_t access_rights)
> 
> This function is only used in add_rule_net_service(), so it should not
> be exported, and we can merge it (into landlock_add_rule_net_port).
> 
  Do I have to ignore it according your next mail thread:
  https://lore.kernel.org/netdev/[e-mail]/
????
>> +{
>> +	int err;
>> +	const struct landlock_id id = {
>> +		.key.data = (__force uintptr_t)htons(port),
>> +		.type = LANDLOCK_KEY_NET_PORT,
>> +	};
>> +
>> +	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
>> +
>> +	/* Transforms relative access rights to absolute ones. */
>> +	access_rights |= LANDLOCK_MASK_ACCESS_NET &
>> +			 ~landlock_get_net_access_mask(ruleset, 0);
>> +
>> +	mutex_lock(&ruleset->lock);
>> +	err = landlock_insert_rule(ruleset, id, access_rights);
>> +	mutex_unlock(&ruleset->lock);
>> +
>> +	return err;
>> +}
>> +
>> +int add_rule_net_service(struct landlock_ruleset *ruleset,
> 
> We should only export functions with a "landlock_" prefix, and "service"
> is now replaced with "port", which gives landlock_add_rule_net_port().
> 
> For consistency, we should also rename add_rule_path_beneath() into
> landlock_add_rule_path_beneath(), move it into fs.c, and merge
> landlock_append_fs_rule() into it (being careful to not move the related
> code to ease review). This change should be part of the "landlock:
> Refactor landlock_add_rule() syscall" patch. Please be careful to keep
> the other changes happening in other patches.
> 
   Should I still update prefix according your suggestions (keep 
add_rule_net_service() in syscalls.c) in the next mail thread or keep it 
as it is:
   https://lore.kernel.org/netdev/[e-mail]/
????
> 
>> +			 const void __user *const rule_attr)
>> +{
>> +	struct landlock_net_port_attr net_port_attr;
>> +	int res;
>> +	access_mask_t mask, bind_access_mask;
>> +
>> +	/* Copies raw user space buffer. */
>> +	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
> 
> We should include <linux/uaccess.h> because of copy_from_user().
> 
> Same for landlock_add_rule_path_beneath().
> 
>> +	if (res)
>> +		return -EFAULT;
>> +
>> +	/*
>> +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
>> +	 * are ignored by network actions.
>> +	 */
>> +	if (!net_port_attr.allowed_access)
>> +		return -ENOMSG;
>> +
>> +	/*
>> +	 * Checks that allowed_access matches the @ruleset constraints
>> +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
>> +	 */
>> +	mask = landlock_get_net_access_mask(ruleset, 0);
>> +	if ((net_port_attr.allowed_access | mask) != mask)
>> +		return -EINVAL;
>> +
>> +	/*
>> +	 * Denies inserting a rule with port 0 (for bind action) or
>> +	 * higher than 65535.
>> +	 */
>> +	bind_access_mask = net_port_attr.allowed_access &
>> +			   LANDLOCK_ACCESS_NET_BIND_TCP;
>> +	if (((net_port_attr.port == 0) &&
>> +	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||
> 
> For context about "port 0 binding" see
> https://lore.kernel.org/all/[e-mail]/
> 
> I previously said:
>>> > To say it another way, we should not allow to add a rule with port
>>> > 0 for
>>> > LANDLOCK_ACCESS_NET_BIND_TCP, but return -EINVAL in this case. This
>>> > limitation should be explained, documented and tested.
> 
> Thinking more about this port 0 for bind (and after an interesting
> discussion with Eric), it would be a mistake to forbid a rule to bind on
> port 0 because this is very useful for some network services, and
> because it would not be reasonable to have an LSM hook to control such
> "random ports". Instead we should document what using this value means
> (i.e. pick a dynamic available port in a range defined by the sysadmin)
> and highlight the fact that it is controlled with the
> /proc/sys/net/ipv4/ip_local_port_range sysctl, which is also used by
> IPv6.
> 
> We then need to test binding on port zero by getting the binded port
> (cf. getsockopt/getsockname) and checking that we can indeed connect to
> it.

   So like I understand refactoring will be like this:
	1. Allow bind for zero port.
	2. Update tests:
		- add rule with port 0;
		- bind "random" port;
		- using getsockname to get binded port;
		- connect to the socket using binded port;
		
  Correct??
> 
>> +	    (net_port_attr.port > U16_MAX))
>> +		return -EINVAL;
>> +
>> +	/* Imports the new rule. */
>> +	return landlock_append_net_rule(ruleset, net_port_attr.port,
>> +					net_port_attr.allowed_access);
>> +}
> 
>> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
>> index 1ede2b9a79b7..9bd0483c64d4 100644
>> --- a/security/landlock/ruleset.h
>> +++ b/security/landlock/ruleset.h
>> @@ -33,13 +33,16 @@
>>  typedef u16 access_mask_t;
>>  /* Makes sure all filesystem access rights can be stored. */
>>  static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS);
>> +/* Makes sure all network access rights can be stored. */
>> +static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET);
>>  /* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */
>>  static_assert(sizeof(unsigned long) >= sizeof(access_mask_t));
>> 
>>  /* Ruleset access masks. */
>> -typedef u16 access_masks_t;
>> +typedef u32 access_masks_t;
>>  /* Makes sure all ruleset access rights can be stored. */
>> -static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS);
>> +static_assert(BITS_PER_TYPE(access_masks_t) >=
>> +	      LANDLOCK_NUM_ACCESS_FS + LANDLOCK_NUM_ACCESS_NET);
>> 
>>  typedef u16 layer_mask_t;
>>  /* Makes sure all layers can be checked. */
>> @@ -84,6 +87,11 @@ enum landlock_key_type {
>>  	 * keys.
>>  	 */
>>  	LANDLOCK_KEY_INODE = 1,
>> +	/**
>> +	 * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's
>> +	 * node keys.
>> +	 */
>> +	LANDLOCK_KEY_NET_PORT = 2,
> 
> You don't need to specify "2".

   Ok. thanks.
> 
> 
>> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
>> index 8a54e87dbb17..da6cbd0032ca 100644
>> --- a/security/landlock/syscalls.c
>> +++ b/security/landlock/syscalls.c
>> @@ -29,6 +29,7 @@
>>  #include "cred.h"
>>  #include "fs.h"
>>  #include "limits.h"
>> +#include "net.h"
>>  #include "ruleset.h"
>>  #include "setup.h"
>> 
>> @@ -74,7 +75,8 @@ static void build_check_abi(void)
>>  {
>>  	struct landlock_ruleset_attr ruleset_attr;
>>  	struct landlock_path_beneath_attr path_beneath_attr;
>> -	size_t ruleset_size, path_beneath_size;
>> +	struct landlock_net_port_attr net_port_attr;
>> +	size_t ruleset_size, path_beneath_size, net_service_size;
> 
> net_port_size

   right. will be fixed.
> .

Konstantin Meskhidze (A) Oct. 10, 2023, 3:31 a.m. UTC | #8

10/9/2023 6:36 PM, Mickaël Salaün пишет:
> On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
>> This commit adds network rules support in the ruleset management
>> helpers and the landlock_create_ruleset syscall.
>> Refactor user space API to support network actions. Add new network
>> access flags, network rule and network attributes. Increment Landlock
>> ABI version. Expand access_masks_t to u32 to be sure network access
>> rights can be stored. Implement socket_bind() and socket_connect()
>> LSM hooks, which enables to restrict TCP socket binding and connection
>> to specific ports.
>> The new landlock_net_port_attr structure has two fields. The allowed_access
>> field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
>> the port value according to the allowed protocol. This field can
>> take up to a 64-bit value [1] but the maximum value depends on the related
>> protocol (e.g. 16-bit for TCP).
>> 
>> [1]
>> https://lore.kernel.org/r/[e-mail]
> 
> Could you please include here the rationale to not tie access rights to
> sockets' file descriptor, and link [2]?
> 
> [2] https://lore.kernel.org/r/[e-mail]

   Ok. I will include this description.
   Thank you.
> .

Mickaël Salaün Oct. 10, 2023, 9:17 a.m. UTC | #9

On Tue, Oct 10, 2023 at 05:20:45AM +0300, Konstantin Meskhidze (A) wrote:
> 
> 
> 10/9/2023 5:12 PM, Mickaël Salaün пишет:
> > On Mon, Oct 02, 2023 at 10:26:36PM +0200, Mickaël Salaün wrote:
> > > Thanks for this new version Konstantin. I pushed this series, with minor
> > > changes, to -next. So far, no warning. But it needs some changes, mostly
> > > kernel-only, but also one with the handling of port 0 with bind (see my
> > > review below).
> > > 
> > > On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
> > > > This commit adds network rules support in the ruleset management
> > > > helpers and the landlock_create_ruleset syscall.
> > > > Refactor user space API to support network actions. Add new network
> > > > access flags, network rule and network attributes. Increment Landlock
> > > > ABI version. Expand access_masks_t to u32 to be sure network access
> > > > rights can be stored. Implement socket_bind() and socket_connect()
> > > > LSM hooks, which enables to restrict TCP socket binding and connection
> > > > to specific ports.
> > > > The new landlock_net_port_attr structure has two fields. The allowed_access
> > > > field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
> > > > the port value according to the allowed protocol. This field can
> > > > take up to a 64-bit value [1] but the maximum value depends on the related
> > > > protocol (e.g. 16-bit for TCP).
> > > > > [1]
> > > > https://lore.kernel.org/r/[e-mail]
> > > > > Signed-off-by: Mickaël Salaün <[e-mail]>
> > > > Signed-off-by: Konstantin Meskhidze <[e-mail]>
> > > > ---
> > > > > Changes since v11:
> > > > * Replace dates with "2022-2023" in net.c/h files headers.
> > > > * Removes WARN_ON_ONCE(!domain) in check_socket_access().
> > > > * Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family).
> > > > * Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT.
> > > > * Renames landlock_net_service_attr to landlock_net_port_attr.
> > > > * Defines two add_rule_net_service() functions according to
> > > >   IS_ENABLED(CONFIG_INET) instead of changing the body of the only
> > > >   function.
> > > > * Adds af_family consistency check while handling AF_UNSPEC specifically.
> > > > * Adds bind_access_mask in add_rule_net_service() to deny all rules with bind
> > > >   action on port zero.
> > > > * Minor fixes.
> > > > * Refactors commit message.
> > > > > Changes since v10:
> > > > * Removes "packed" attribute.
> > > > * Applies Mickaёl's patch with some refactoring.
> > > > * Deletes get_port() and check_addrlen() helpers.
> > > > * Refactors check_socket_access() by squashing get_port() and
> > > >   check_addrlen() helpers into it.
> > > > * Fixes commit message.
> > > > > Changes since v9:
> > > > * Changes UAPI port field to __u64.
> > > > * Moves shared code into check_socket_access().
> > > > * Adds get_raw_handled_net_accesses() and
> > > >   get_current_net_domain() helpers.
> > > > * Minor fixes.
> > > > > Changes since v8:
> > > > * Squashes commits.
> > > > * Refactors commit message.
> > > > * Changes UAPI port field to __be16.
> > > > * Changes logic of bind/connect hooks with AF_UNSPEC families.
> > > > * Adds address length checking.
> > > > * Minor fixes.
> > > > > Changes since v7:
> > > > * Squashes commits.
> > > > * Increments ABI version to 4.
> > > > * Refactors commit message.
> > > > * Minor fixes.
> > > > > Changes since v6:
> > > > * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
> > > >   because it OR values.
> > > > * Makes landlock_add_net_access_mask() more resilient incorrect values.
> > > > * Refactors landlock_get_net_access_mask().
> > > > * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
> > > >   LANDLOCK_NUM_ACCESS_FS as value.
> > > > * Updates access_masks_t to u32 to support network access actions.
> > > > * Refactors landlock internal functions to support network actions with
> > > >   landlock_key/key_type/id types.
> > > > > Changes since v5:
> > > > * Gets rid of partial revert from landlock_add_rule
> > > > syscall.
> > > > * Formats code with clang-format-14.
> > > > > Changes since v4:
> > > > * Refactors landlock_create_ruleset() - splits ruleset and
> > > > masks checks.
> > > > * Refactors landlock_create_ruleset() and landlock mask
> > > > setters/getters to support two rule types.
> > > > * Refactors landlock_add_rule syscall add_rule_path_beneath
> > > > function by factoring out get_ruleset_from_fd() and
> > > > landlock_put_ruleset().
> > > > > Changes since v3:
> > > > * Splits commit.
> > > > * Adds network rule support for internal landlock functions.
> > > > * Adds set_mask and get_mask for network.
> > > > * Adds rb_root root_net_port.
> > > > > ---
> > > >  include/uapi/linux/landlock.h                |  47 ++++
> > > >  security/landlock/Kconfig                    |   3 +-
> > > >  security/landlock/Makefile                   |   2 +
> > > >  security/landlock/limits.h                   |   5 +
> > > >  security/landlock/net.c                      | 241 +++++++++++++++++++
> > > >  security/landlock/net.h                      |  35 +++
> > > >  security/landlock/ruleset.c                  |  62 ++++-
> > > >  security/landlock/ruleset.h                  |  59 ++++-
> > > >  security/landlock/setup.c                    |   2 +
> > > >  security/landlock/syscalls.c                 |  33 ++-
> > > >  tools/testing/selftests/landlock/base_test.c |   2 +-
> > > >  11 files changed, 467 insertions(+), 24 deletions(-)
> > > >  create mode 100644 security/landlock/net.c
> > > >  create mode 100644 security/landlock/net.h
> > > >
> > 
> > > > diff --git a/security/landlock/net.c b/security/landlock/net.c
> > > > new file mode 100644
> > > > index 000000000000..62b830653e25
> > > > --- /dev/null
> > > > +++ b/security/landlock/net.c
> > > > @@ -0,0 +1,241 @@
> > > > +// SPDX-License-Identifier: GPL-2.0-only
> > > > +/*
> > > > + * Landlock LSM - Network management and hooks
> > > > + *
> > > > + * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
> > > > + * Copyright © 2022-2023 Microsoft Corporation
> > > > + */
> > > > +
> > > > +#include <linux/in.h>
> > > > +#include <linux/net.h>
> > > > +#include <linux/socket.h>
> > > > +#include <net/ipv6.h>
> > > > +
> > > > +#include "common.h"
> > > > +#include "cred.h"
> > > > +#include "limits.h"
> > > > +#include "net.h"
> > > > +#include "ruleset.h"
> > > > +
> > > > +int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
> > > > +			     const u16 port, access_mask_t access_rights)
> > > 
> > > This function is only used in add_rule_net_service(), so it should not
> > > be exported, and we can merge it (into landlock_add_rule_net_port).
> > > 
> > > > +{
> > > > +	int err;
> > > > +	const struct landlock_id id = {
> > > > +		.key.data = (__force uintptr_t)htons(port),
> > > > +		.type = LANDLOCK_KEY_NET_PORT,
> > > > +	};
> > > > +
> > > > +	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
> > > > +
> > > > +	/* Transforms relative access rights to absolute ones. */
> > > > +	access_rights |= LANDLOCK_MASK_ACCESS_NET &
> > > > +			 ~landlock_get_net_access_mask(ruleset, 0);
> > > > +
> > > > +	mutex_lock(&ruleset->lock);
> > > > +	err = landlock_insert_rule(ruleset, id, access_rights);
> > > > +	mutex_unlock(&ruleset->lock);
> > > > +
> > > > +	return err;
> > > > +}
> > > > +
> > > > +int add_rule_net_service(struct landlock_ruleset *ruleset,
> > > 
> > > We should only export functions with a "landlock_" prefix, and "service"
> > > is now replaced with "port", which gives landlock_add_rule_net_port().
> > > 
> > > For consistency, we should also rename add_rule_path_beneath() into
> > > landlock_add_rule_path_beneath(), move it into fs.c, and merge
> > > landlock_append_fs_rule() into it (being careful to not move the related
> > > code to ease review). This change should be part of the "landlock:
> > > Refactor landlock_add_rule() syscall" patch. Please be careful to keep
> > > the other changes happening in other patches.
> > > 
> > > 
> > > > +			 const void __user *const rule_attr)
> > > > +{
> > > > +	struct landlock_net_port_attr net_port_attr;
> > > > +	int res;
> > > > +	access_mask_t mask, bind_access_mask;
> > > > +
> > > > +	/* Copies raw user space buffer. */
> > > > +	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
> > > 
> > > We should include <linux/uaccess.h> because of copy_from_user().
> > > 
> > > Same for landlock_add_rule_path_beneath().
> > > 
> > > > +	if (res)
> > > > +		return -EFAULT;
> > > > +
> > > > +	/*
> > > > +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
> > > > +	 * are ignored by network actions.
> > > > +	 */
> > > > +	if (!net_port_attr.allowed_access)
> > > > +		return -ENOMSG;
> > > > +
> > > > +	/*
> > > > +	 * Checks that allowed_access matches the @ruleset constraints
> > > > +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
> > > > +	 */
> > > > +	mask = landlock_get_net_access_mask(ruleset, 0);
> > > > +	if ((net_port_attr.allowed_access | mask) != mask)
> > > > +		return -EINVAL;
> > > > +
> > > > +	/*
> > > > +	 * Denies inserting a rule with port 0 (for bind action) or
> > > > +	 * higher than 65535.
> > > > +	 */
> > > > +	bind_access_mask = net_port_attr.allowed_access &
> > > > +			   LANDLOCK_ACCESS_NET_BIND_TCP;
> > > > +	if (((net_port_attr.port == 0) &&
> > > > +	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||
> > > > +	    (net_port_attr.port > U16_MAX))
> > > > +		return -EINVAL;
> > > > +
> > > > +	/* Imports the new rule. */
> > > > +	return landlock_append_net_rule(ruleset, net_port_attr.port,
> > > > +					net_port_attr.allowed_access);
> > > > +}
> > 
> > Please ignore the above suggestions. Thinking more about this, let's
> > keep the static add_rule_net_service() in syscalls.c, and only make the
> > inline landlock_add_rule_net_service() return -EAFNOSUPPORT (which is
> > already the case with this patch when CONFIG_INET is not set). This will
> > slightly change the current semantic but enable to check all the
> > syscalls arguments even if CONFIG_INET is not set, which is a good thing
> > (and should be reflected in tests). It is better to group all the code
> > handling user space memory copying and ABI specificities in the
> > syscalls.c file. This approach is simpler, it will avoid the exported
> > function issues (e.g. add_rule_net_service), and it will not require
> > more changes to the fs.[ch] files.
> > .
>   Ok.Will be moved back to syscalls.c.
>   What about renaming to add_rule_net_service()->add_rule_net_port() ???

Yes please rename it, there should be no mention of "net_service"
anymore.

Mickaël Salaün Oct. 10, 2023, 9:28 a.m. UTC | #10

On Tue, Oct 10, 2023 at 06:29:56AM +0300, Konstantin Meskhidze (A) wrote:
> 
> 
> 10/2/2023 11:26 PM, Mickaël Salaün пишет:
> > Thanks for this new version Konstantin. I pushed this series, with minor
> > changes, to -next. So far, no warning. But it needs some changes, mostly
> > kernel-only, but also one with the handling of port 0 with bind (see my
> > review below).
> > 
> > On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
> > > This commit adds network rules support in the ruleset management
> > > helpers and the landlock_create_ruleset syscall.
> > > Refactor user space API to support network actions. Add new network
> > > access flags, network rule and network attributes. Increment Landlock
> > > ABI version. Expand access_masks_t to u32 to be sure network access
> > > rights can be stored. Implement socket_bind() and socket_connect()
> > > LSM hooks, which enables to restrict TCP socket binding and connection
> > > to specific ports.
> > > The new landlock_net_port_attr structure has two fields. The allowed_access
> > > field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
> > > the port value according to the allowed protocol. This field can
> > > take up to a 64-bit value [1] but the maximum value depends on the related
> > > protocol (e.g. 16-bit for TCP).
> > > 
> > > [1]
> > > https://lore.kernel.org/r/[e-mail]
> > > 
> > > Signed-off-by: Mickaël Salaün <[e-mail]>
> > > Signed-off-by: Konstantin Meskhidze <[e-mail]>
> > > ---
> > > 
> > > Changes since v11:
> > > * Replace dates with "2022-2023" in net.c/h files headers.
> > > * Removes WARN_ON_ONCE(!domain) in check_socket_access().
> > > * Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family).
> > > * Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT.
> > > * Renames landlock_net_service_attr to landlock_net_port_attr.
> > > * Defines two add_rule_net_service() functions according to
> > >   IS_ENABLED(CONFIG_INET) instead of changing the body of the only
> > >   function.
> > > * Adds af_family consistency check while handling AF_UNSPEC specifically.
> > > * Adds bind_access_mask in add_rule_net_service() to deny all rules with bind
> > >   action on port zero.
> > > * Minor fixes.
> > > * Refactors commit message.
> > > 
> > > Changes since v10:
> > > * Removes "packed" attribute.
> > > * Applies Mickaёl's patch with some refactoring.
> > > * Deletes get_port() and check_addrlen() helpers.
> > > * Refactors check_socket_access() by squashing get_port() and
> > >   check_addrlen() helpers into it.
> > > * Fixes commit message.
> > > 
> > > Changes since v9:
> > > * Changes UAPI port field to __u64.
> > > * Moves shared code into check_socket_access().
> > > * Adds get_raw_handled_net_accesses() and
> > >   get_current_net_domain() helpers.
> > > * Minor fixes.
> > > 
> > > Changes since v8:
> > > * Squashes commits.
> > > * Refactors commit message.
> > > * Changes UAPI port field to __be16.
> > > * Changes logic of bind/connect hooks with AF_UNSPEC families.
> > > * Adds address length checking.
> > > * Minor fixes.
> > > 
> > > Changes since v7:
> > > * Squashes commits.
> > > * Increments ABI version to 4.
> > > * Refactors commit message.
> > > * Minor fixes.
> > > 
> > > Changes since v6:
> > > * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
> > >   because it OR values.
> > > * Makes landlock_add_net_access_mask() more resilient incorrect values.
> > > * Refactors landlock_get_net_access_mask().
> > > * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
> > >   LANDLOCK_NUM_ACCESS_FS as value.
> > > * Updates access_masks_t to u32 to support network access actions.
> > > * Refactors landlock internal functions to support network actions with
> > >   landlock_key/key_type/id types.
> > > 
> > > Changes since v5:
> > > * Gets rid of partial revert from landlock_add_rule
> > > syscall.
> > > * Formats code with clang-format-14.
> > > 
> > > Changes since v4:
> > > * Refactors landlock_create_ruleset() - splits ruleset and
> > > masks checks.
> > > * Refactors landlock_create_ruleset() and landlock mask
> > > setters/getters to support two rule types.
> > > * Refactors landlock_add_rule syscall add_rule_path_beneath
> > > function by factoring out get_ruleset_from_fd() and
> > > landlock_put_ruleset().
> > > 
> > > Changes since v3:
> > > * Splits commit.
> > > * Adds network rule support for internal landlock functions.
> > > * Adds set_mask and get_mask for network.
> > > * Adds rb_root root_net_port.
> > > 
> > > ---
> > >  include/uapi/linux/landlock.h                |  47 ++++
> > >  security/landlock/Kconfig                    |   3 +-
> > >  security/landlock/Makefile                   |   2 +
> > >  security/landlock/limits.h                   |   5 +
> > >  security/landlock/net.c                      | 241 +++++++++++++++++++
> > >  security/landlock/net.h                      |  35 +++
> > >  security/landlock/ruleset.c                  |  62 ++++-
> > >  security/landlock/ruleset.h                  |  59 ++++-
> > >  security/landlock/setup.c                    |   2 +
> > >  security/landlock/syscalls.c                 |  33 ++-
> > >  tools/testing/selftests/landlock/base_test.c |   2 +-
> > >  11 files changed, 467 insertions(+), 24 deletions(-)
> > >  create mode 100644 security/landlock/net.c
> > >  create mode 100644 security/landlock/net.h
> > > 
> > > diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
> > > index 81d09ef9aa50..3b8400e8a4d9 100644
> > > --- a/include/uapi/linux/landlock.h
> > > +++ b/include/uapi/linux/landlock.h
> > > @@ -31,6 +31,12 @@ struct landlock_ruleset_attr {
> > >  	 * this access right.
> > >  	 */
> > >  	__u64 handled_access_fs;
> > > +	/**
> > > +	 * @handled_access_net: Bitmask of actions (cf. `Network flags`_)
> > > +	 * that is handled by this ruleset and should then be forbidden if no
> > > +	 * rule explicitly allow them.
> > > +	 */
> > > +	__u64 handled_access_net;
> > >  };
> > > 
> > >  /*
> > > @@ -54,6 +60,11 @@ enum landlock_rule_type {
> > >  	 * landlock_path_beneath_attr .
> > >  	 */
> > >  	LANDLOCK_RULE_PATH_BENEATH = 1,
> > > +	/**
> > > +	 * @LANDLOCK_RULE_NET_PORT: Type of a &struct
> > > +	 * landlock_net_port_attr .
> > > +	 */
> > > +	LANDLOCK_RULE_NET_PORT = 2,
> > >  };
> > > 
> > >  /**
> > > @@ -79,6 +90,23 @@ struct landlock_path_beneath_attr {
> > >  	 */
> > >  } __attribute__((packed));
> > > 
> > > +/**
> > > + * struct landlock_net_port_attr - Network service definition
> > 
> > "Network port definition"
> 
>    Ok. Thanks.
> > 
> > 
> > > diff --git a/security/landlock/Kconfig b/security/landlock/Kconfig
> > > index c1e862a38410..10c099097533 100644
> > > --- a/security/landlock/Kconfig
> > > +++ b/security/landlock/Kconfig
> > > @@ -2,7 +2,8 @@
> > > 
> > >  config SECURITY_LANDLOCK
> > >  	bool "Landlock support"
> > > -	depends on SECURITY
> > > +	depends on SECURITY && !ARCH_EPHEMERAL_INODES
> > 
> > !ARCH_EPHEMERAL_INODES is definitely gone now.
> 
>   Ok. Got it.
> > 
> > > +	select SECURITY_NETWORK
> > >  	select SECURITY_PATH
> > >  	help
> > >  	  Landlock is a sandboxing mechanism that enables processes to restrict
> > > diff --git a/security/landlock/Makefile b/security/landlock/Makefile
> > > index 7bbd2f413b3e..53d3c92ae22e 100644
> > > --- a/security/landlock/Makefile
> > > +++ b/security/landlock/Makefile
> > > @@ -2,3 +2,5 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o
> > > 
> > >  landlock-y := setup.o syscalls.o object.o ruleset.o \
> > >  	cred.o ptrace.o fs.o
> > > +
> > > +landlock-$(CONFIG_INET) += net.o
> > > \ No newline at end of file
> > > diff --git a/security/landlock/limits.h b/security/landlock/limits.h
> > > index bafb3b8dc677..93c9c6f91556 100644
> > > --- a/security/landlock/limits.h
> > > +++ b/security/landlock/limits.h
> > > @@ -23,6 +23,11 @@
> > >  #define LANDLOCK_NUM_ACCESS_FS		__const_hweight64(LANDLOCK_MASK_ACCESS_FS)
> > >  #define LANDLOCK_SHIFT_ACCESS_FS	0
> > > 
> > > +#define LANDLOCK_LAST_ACCESS_NET	LANDLOCK_ACCESS_NET_CONNECT_TCP
> > > +#define LANDLOCK_MASK_ACCESS_NET	((LANDLOCK_LAST_ACCESS_NET << 1) - 1)
> > > +#define LANDLOCK_NUM_ACCESS_NET		__const_hweight64(LANDLOCK_MASK_ACCESS_NET)
> > > +#define LANDLOCK_SHIFT_ACCESS_NET	LANDLOCK_NUM_ACCESS_FS
> > > +
> > >  /* clang-format on */
> > > 
> > >  #endif /* _SECURITY_LANDLOCK_LIMITS_H */
> > > diff --git a/security/landlock/net.c b/security/landlock/net.c
> > > new file mode 100644
> > > index 000000000000..62b830653e25
> > > --- /dev/null
> > > +++ b/security/landlock/net.c
> > > @@ -0,0 +1,241 @@
> > > +// SPDX-License-Identifier: GPL-2.0-only
> > > +/*
> > > + * Landlock LSM - Network management and hooks
> > > + *
> > > + * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
> > > + * Copyright © 2022-2023 Microsoft Corporation
> > > + */
> > > +
> > > +#include <linux/in.h>
> > > +#include <linux/net.h>
> > > +#include <linux/socket.h>
> > > +#include <net/ipv6.h>
> > > +
> > > +#include "common.h"
> > > +#include "cred.h"
> > > +#include "limits.h"
> > > +#include "net.h"
> > > +#include "ruleset.h"
> > > +
> > > +int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
> > > +			     const u16 port, access_mask_t access_rights)
> > 
> > This function is only used in add_rule_net_service(), so it should not
> > be exported, and we can merge it (into landlock_add_rule_net_port).
> > 
>  Do I have to ignore it according your next mail thread:
>  https://lore.kernel.org/netdev/[e-mail]/
> ????

Yes please ignore this part, the latest mail prevails. This should be a
static function.

> > > +{
> > > +	int err;
> > > +	const struct landlock_id id = {
> > > +		.key.data = (__force uintptr_t)htons(port),
> > > +		.type = LANDLOCK_KEY_NET_PORT,
> > > +	};
> > > +
> > > +	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
> > > +
> > > +	/* Transforms relative access rights to absolute ones. */
> > > +	access_rights |= LANDLOCK_MASK_ACCESS_NET &
> > > +			 ~landlock_get_net_access_mask(ruleset, 0);
> > > +
> > > +	mutex_lock(&ruleset->lock);
> > > +	err = landlock_insert_rule(ruleset, id, access_rights);
> > > +	mutex_unlock(&ruleset->lock);
> > > +
> > > +	return err;
> > > +}
> > > +
> > > +int add_rule_net_service(struct landlock_ruleset *ruleset,
> > 
> > We should only export functions with a "landlock_" prefix, and "service"
> > is now replaced with "port", which gives landlock_add_rule_net_port().
> > 
> > For consistency, we should also rename add_rule_path_beneath() into
> > landlock_add_rule_path_beneath(), move it into fs.c, and merge
> > landlock_append_fs_rule() into it (being careful to not move the related
> > code to ease review). This change should be part of the "landlock:
> > Refactor landlock_add_rule() syscall" patch. Please be careful to keep
> > the other changes happening in other patches.
> > 
>   Should I still update prefix according your suggestions (keep
> add_rule_net_service() in syscalls.c) in the next mail thread or keep it as
> it is:
>   https://lore.kernel.org/netdev/[e-mail]/
> ????

No, the prefix notation is only useful for exported functions, just
renamed it to add_rule_net_port() and make it static.

> > 
> > > +			 const void __user *const rule_attr)
> > > +{
> > > +	struct landlock_net_port_attr net_port_attr;
> > > +	int res;
> > > +	access_mask_t mask, bind_access_mask;
> > > +
> > > +	/* Copies raw user space buffer. */
> > > +	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
> > 
> > We should include <linux/uaccess.h> because of copy_from_user().
> > 
> > Same for landlock_add_rule_path_beneath().

Same as above, this is not relevant anymore.

> > 
> > > +	if (res)
> > > +		return -EFAULT;
> > > +
> > > +	/*
> > > +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
> > > +	 * are ignored by network actions.
> > > +	 */
> > > +	if (!net_port_attr.allowed_access)
> > > +		return -ENOMSG;
> > > +
> > > +	/*
> > > +	 * Checks that allowed_access matches the @ruleset constraints
> > > +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
> > > +	 */
> > > +	mask = landlock_get_net_access_mask(ruleset, 0);
> > > +	if ((net_port_attr.allowed_access | mask) != mask)
> > > +		return -EINVAL;
> > > +
> > > +	/*
> > > +	 * Denies inserting a rule with port 0 (for bind action) or
> > > +	 * higher than 65535.
> > > +	 */
> > > +	bind_access_mask = net_port_attr.allowed_access &
> > > +			   LANDLOCK_ACCESS_NET_BIND_TCP;
> > > +	if (((net_port_attr.port == 0) &&
> > > +	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||
> > 
> > For context about "port 0 binding" see
> > https://lore.kernel.org/all/[e-mail]/
> > 
> > I previously said:
> > > > > To say it another way, we should not allow to add a rule with port
> > > > > 0 for
> > > > > LANDLOCK_ACCESS_NET_BIND_TCP, but return -EINVAL in this case. This
> > > > > limitation should be explained, documented and tested.
> > 
> > Thinking more about this port 0 for bind (and after an interesting
> > discussion with Eric), it would be a mistake to forbid a rule to bind on
> > port 0 because this is very useful for some network services, and
> > because it would not be reasonable to have an LSM hook to control such
> > "random ports". Instead we should document what using this value means
> > (i.e. pick a dynamic available port in a range defined by the sysadmin)
> > and highlight the fact that it is controlled with the
> > /proc/sys/net/ipv4/ip_local_port_range sysctl, which is also used by
> > IPv6.
> > 
> > We then need to test binding on port zero by getting the binded port
> > (cf. getsockopt/getsockname) and checking that we can indeed connect to
> > it.
> 
>   So like I understand refactoring will be like this:
> 	1. Allow bind for zero port.
> 	2. Update tests:
> 		- add rule with port 0;
> 		- bind "random" port;
> 		- using getsockname to get binded port;
> 		- connect to the socket using binded port;
> 		
>  Correct??

Yes. You can also extend this test to try binding to a lower port (e.g.
1024, value of srv0.port), not part of ip_local_port_range, which should
then be denied.

> > 
> > > +	    (net_port_attr.port > U16_MAX))
> > > +		return -EINVAL;
> > > +
> > > +	/* Imports the new rule. */
> > > +	return landlock_append_net_rule(ruleset, net_port_attr.port,
> > > +					net_port_attr.allowed_access);
> > > +}
> > 
> > > diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
> > > index 1ede2b9a79b7..9bd0483c64d4 100644
> > > --- a/security/landlock/ruleset.h
> > > +++ b/security/landlock/ruleset.h
> > > @@ -33,13 +33,16 @@
> > >  typedef u16 access_mask_t;
> > >  /* Makes sure all filesystem access rights can be stored. */
> > >  static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS);
> > > +/* Makes sure all network access rights can be stored. */
> > > +static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET);
> > >  /* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */
> > >  static_assert(sizeof(unsigned long) >= sizeof(access_mask_t));
> > > 
> > >  /* Ruleset access masks. */
> > > -typedef u16 access_masks_t;
> > > +typedef u32 access_masks_t;
> > >  /* Makes sure all ruleset access rights can be stored. */
> > > -static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS);
> > > +static_assert(BITS_PER_TYPE(access_masks_t) >=
> > > +	      LANDLOCK_NUM_ACCESS_FS + LANDLOCK_NUM_ACCESS_NET);
> > > 
> > >  typedef u16 layer_mask_t;
> > >  /* Makes sure all layers can be checked. */
> > > @@ -84,6 +87,11 @@ enum landlock_key_type {
> > >  	 * keys.
> > >  	 */
> > >  	LANDLOCK_KEY_INODE = 1,
> > > +	/**
> > > +	 * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's
> > > +	 * node keys.
> > > +	 */
> > > +	LANDLOCK_KEY_NET_PORT = 2,
> > 
> > You don't need to specify "2".
> 
>   Ok. thanks.
> > 
> > 
> > > diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
> > > index 8a54e87dbb17..da6cbd0032ca 100644
> > > --- a/security/landlock/syscalls.c
> > > +++ b/security/landlock/syscalls.c
> > > @@ -29,6 +29,7 @@
> > >  #include "cred.h"
> > >  #include "fs.h"
> > >  #include "limits.h"
> > > +#include "net.h"
> > >  #include "ruleset.h"
> > >  #include "setup.h"
> > > 
> > > @@ -74,7 +75,8 @@ static void build_check_abi(void)
> > >  {
> > >  	struct landlock_ruleset_attr ruleset_attr;
> > >  	struct landlock_path_beneath_attr path_beneath_attr;
> > > -	size_t ruleset_size, path_beneath_size;
> > > +	struct landlock_net_port_attr net_port_attr;
> > > +	size_t ruleset_size, path_beneath_size, net_service_size;
> > 
> > net_port_size
> 
>   right. will be fixed.
> > .

Konstantin Meskhidze (A) Oct. 10, 2023, 11:21 a.m. UTC | #11

10/10/2023 12:28 PM, Mickaël Salaün пишет:
> On Tue, Oct 10, 2023 at 06:29:56AM +0300, Konstantin Meskhidze (A) wrote:
>> 
>> 
>> 10/2/2023 11:26 PM, Mickaël Salaün пишет:
>> > Thanks for this new version Konstantin. I pushed this series, with minor
>> > changes, to -next. So far, no warning. But it needs some changes, mostly
>> > kernel-only, but also one with the handling of port 0 with bind (see my
>> > review below).
>> > 
>> > On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
>> > > This commit adds network rules support in the ruleset management
>> > > helpers and the landlock_create_ruleset syscall.
>> > > Refactor user space API to support network actions. Add new network
>> > > access flags, network rule and network attributes. Increment Landlock
>> > > ABI version. Expand access_masks_t to u32 to be sure network access
>> > > rights can be stored. Implement socket_bind() and socket_connect()
>> > > LSM hooks, which enables to restrict TCP socket binding and connection
>> > > to specific ports.
>> > > The new landlock_net_port_attr structure has two fields. The allowed_access
>> > > field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
>> > > the port value according to the allowed protocol. This field can
>> > > take up to a 64-bit value [1] but the maximum value depends on the related
>> > > protocol (e.g. 16-bit for TCP).
>> > > 
>> > > [1]
>> > > https://lore.kernel.org/r/[e-mail]
>> > > 
>> > > Signed-off-by: Mickaël Salaün <[e-mail]>
>> > > Signed-off-by: Konstantin Meskhidze <[e-mail]>
>> > > ---
>> > > 
>> > > Changes since v11:
>> > > * Replace dates with "2022-2023" in net.c/h files headers.
>> > > * Removes WARN_ON_ONCE(!domain) in check_socket_access().
>> > > * Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family).
>> > > * Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT.
>> > > * Renames landlock_net_service_attr to landlock_net_port_attr.
>> > > * Defines two add_rule_net_service() functions according to
>> > >   IS_ENABLED(CONFIG_INET) instead of changing the body of the only
>> > >   function.
>> > > * Adds af_family consistency check while handling AF_UNSPEC specifically.
>> > > * Adds bind_access_mask in add_rule_net_service() to deny all rules with bind
>> > >   action on port zero.
>> > > * Minor fixes.
>> > > * Refactors commit message.
>> > > 
>> > > Changes since v10:
>> > > * Removes "packed" attribute.
>> > > * Applies Mickaёl's patch with some refactoring.
>> > > * Deletes get_port() and check_addrlen() helpers.
>> > > * Refactors check_socket_access() by squashing get_port() and
>> > >   check_addrlen() helpers into it.
>> > > * Fixes commit message.
>> > > 
>> > > Changes since v9:
>> > > * Changes UAPI port field to __u64.
>> > > * Moves shared code into check_socket_access().
>> > > * Adds get_raw_handled_net_accesses() and
>> > >   get_current_net_domain() helpers.
>> > > * Minor fixes.
>> > > 
>> > > Changes since v8:
>> > > * Squashes commits.
>> > > * Refactors commit message.
>> > > * Changes UAPI port field to __be16.
>> > > * Changes logic of bind/connect hooks with AF_UNSPEC families.
>> > > * Adds address length checking.
>> > > * Minor fixes.
>> > > 
>> > > Changes since v7:
>> > > * Squashes commits.
>> > > * Increments ABI version to 4.
>> > > * Refactors commit message.
>> > > * Minor fixes.
>> > > 
>> > > Changes since v6:
>> > > * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
>> > >   because it OR values.
>> > > * Makes landlock_add_net_access_mask() more resilient incorrect values.
>> > > * Refactors landlock_get_net_access_mask().
>> > > * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
>> > >   LANDLOCK_NUM_ACCESS_FS as value.
>> > > * Updates access_masks_t to u32 to support network access actions.
>> > > * Refactors landlock internal functions to support network actions with
>> > >   landlock_key/key_type/id types.
>> > > 
>> > > Changes since v5:
>> > > * Gets rid of partial revert from landlock_add_rule
>> > > syscall.
>> > > * Formats code with clang-format-14.
>> > > 
>> > > Changes since v4:
>> > > * Refactors landlock_create_ruleset() - splits ruleset and
>> > > masks checks.
>> > > * Refactors landlock_create_ruleset() and landlock mask
>> > > setters/getters to support two rule types.
>> > > * Refactors landlock_add_rule syscall add_rule_path_beneath
>> > > function by factoring out get_ruleset_from_fd() and
>> > > landlock_put_ruleset().
>> > > 
>> > > Changes since v3:
>> > > * Splits commit.
>> > > * Adds network rule support for internal landlock functions.
>> > > * Adds set_mask and get_mask for network.
>> > > * Adds rb_root root_net_port.
>> > > 
>> > > ---
>> > >  include/uapi/linux/landlock.h                |  47 ++++
>> > >  security/landlock/Kconfig                    |   3 +-
>> > >  security/landlock/Makefile                   |   2 +
>> > >  security/landlock/limits.h                   |   5 +
>> > >  security/landlock/net.c                      | 241 +++++++++++++++++++
>> > >  security/landlock/net.h                      |  35 +++
>> > >  security/landlock/ruleset.c                  |  62 ++++-
>> > >  security/landlock/ruleset.h                  |  59 ++++-
>> > >  security/landlock/setup.c                    |   2 +
>> > >  security/landlock/syscalls.c                 |  33 ++-
>> > >  tools/testing/selftests/landlock/base_test.c |   2 +-
>> > >  11 files changed, 467 insertions(+), 24 deletions(-)
>> > >  create mode 100644 security/landlock/net.c
>> > >  create mode 100644 security/landlock/net.h
>> > > 
>> > > diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
>> > > index 81d09ef9aa50..3b8400e8a4d9 100644
>> > > --- a/include/uapi/linux/landlock.h
>> > > +++ b/include/uapi/linux/landlock.h
>> > > @@ -31,6 +31,12 @@ struct landlock_ruleset_attr {
>> > >  	 * this access right.
>> > >  	 */
>> > >  	__u64 handled_access_fs;
>> > > +	/**
>> > > +	 * @handled_access_net: Bitmask of actions (cf. `Network flags`_)
>> > > +	 * that is handled by this ruleset and should then be forbidden if no
>> > > +	 * rule explicitly allow them.
>> > > +	 */
>> > > +	__u64 handled_access_net;
>> > >  };
>> > > 
>> > >  /*
>> > > @@ -54,6 +60,11 @@ enum landlock_rule_type {
>> > >  	 * landlock_path_beneath_attr .
>> > >  	 */
>> > >  	LANDLOCK_RULE_PATH_BENEATH = 1,
>> > > +	/**
>> > > +	 * @LANDLOCK_RULE_NET_PORT: Type of a &struct
>> > > +	 * landlock_net_port_attr .
>> > > +	 */
>> > > +	LANDLOCK_RULE_NET_PORT = 2,
>> > >  };
>> > > 
>> > >  /**
>> > > @@ -79,6 +90,23 @@ struct landlock_path_beneath_attr {
>> > >  	 */
>> > >  } __attribute__((packed));
>> > > 
>> > > +/**
>> > > + * struct landlock_net_port_attr - Network service definition
>> > 
>> > "Network port definition"
>> 
>>    Ok. Thanks.
>> > 
>> > 
>> > > diff --git a/security/landlock/Kconfig b/security/landlock/Kconfig
>> > > index c1e862a38410..10c099097533 100644
>> > > --- a/security/landlock/Kconfig
>> > > +++ b/security/landlock/Kconfig
>> > > @@ -2,7 +2,8 @@
>> > > 
>> > >  config SECURITY_LANDLOCK
>> > >  	bool "Landlock support"
>> > > -	depends on SECURITY
>> > > +	depends on SECURITY && !ARCH_EPHEMERAL_INODES
>> > 
>> > !ARCH_EPHEMERAL_INODES is definitely gone now.
>> 
>>   Ok. Got it.
>> > 
>> > > +	select SECURITY_NETWORK
>> > >  	select SECURITY_PATH
>> > >  	help
>> > >  	  Landlock is a sandboxing mechanism that enables processes to restrict
>> > > diff --git a/security/landlock/Makefile b/security/landlock/Makefile
>> > > index 7bbd2f413b3e..53d3c92ae22e 100644
>> > > --- a/security/landlock/Makefile
>> > > +++ b/security/landlock/Makefile
>> > > @@ -2,3 +2,5 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o
>> > > 
>> > >  landlock-y := setup.o syscalls.o object.o ruleset.o \
>> > >  	cred.o ptrace.o fs.o
>> > > +
>> > > +landlock-$(CONFIG_INET) += net.o
>> > > \ No newline at end of file
>> > > diff --git a/security/landlock/limits.h b/security/landlock/limits.h
>> > > index bafb3b8dc677..93c9c6f91556 100644
>> > > --- a/security/landlock/limits.h
>> > > +++ b/security/landlock/limits.h
>> > > @@ -23,6 +23,11 @@
>> > >  #define LANDLOCK_NUM_ACCESS_FS		__const_hweight64(LANDLOCK_MASK_ACCESS_FS)
>> > >  #define LANDLOCK_SHIFT_ACCESS_FS	0
>> > > 
>> > > +#define LANDLOCK_LAST_ACCESS_NET	LANDLOCK_ACCESS_NET_CONNECT_TCP
>> > > +#define LANDLOCK_MASK_ACCESS_NET	((LANDLOCK_LAST_ACCESS_NET << 1) - 1)
>> > > +#define LANDLOCK_NUM_ACCESS_NET		__const_hweight64(LANDLOCK_MASK_ACCESS_NET)
>> > > +#define LANDLOCK_SHIFT_ACCESS_NET	LANDLOCK_NUM_ACCESS_FS
>> > > +
>> > >  /* clang-format on */
>> > > 
>> > >  #endif /* _SECURITY_LANDLOCK_LIMITS_H */
>> > > diff --git a/security/landlock/net.c b/security/landlock/net.c
>> > > new file mode 100644
>> > > index 000000000000..62b830653e25
>> > > --- /dev/null
>> > > +++ b/security/landlock/net.c
>> > > @@ -0,0 +1,241 @@
>> > > +// SPDX-License-Identifier: GPL-2.0-only
>> > > +/*
>> > > + * Landlock LSM - Network management and hooks
>> > > + *
>> > > + * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
>> > > + * Copyright © 2022-2023 Microsoft Corporation
>> > > + */
>> > > +
>> > > +#include <linux/in.h>
>> > > +#include <linux/net.h>
>> > > +#include <linux/socket.h>
>> > > +#include <net/ipv6.h>
>> > > +
>> > > +#include "common.h"
>> > > +#include "cred.h"
>> > > +#include "limits.h"
>> > > +#include "net.h"
>> > > +#include "ruleset.h"
>> > > +
>> > > +int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
>> > > +			     const u16 port, access_mask_t access_rights)
>> > 
>> > This function is only used in add_rule_net_service(), so it should not
>> > be exported, and we can merge it (into landlock_add_rule_net_port).
>> > 
>>  Do I have to ignore it according your next mail thread:
>>  https://lore.kernel.org/netdev/[e-mail]/
>> ????
> 
> Yes please ignore this part, the latest mail prevails. This should be a
> static function.

  Ok.
> 
>> > > +{
>> > > +	int err;
>> > > +	const struct landlock_id id = {
>> > > +		.key.data = (__force uintptr_t)htons(port),
>> > > +		.type = LANDLOCK_KEY_NET_PORT,
>> > > +	};
>> > > +
>> > > +	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
>> > > +
>> > > +	/* Transforms relative access rights to absolute ones. */
>> > > +	access_rights |= LANDLOCK_MASK_ACCESS_NET &
>> > > +			 ~landlock_get_net_access_mask(ruleset, 0);
>> > > +
>> > > +	mutex_lock(&ruleset->lock);
>> > > +	err = landlock_insert_rule(ruleset, id, access_rights);
>> > > +	mutex_unlock(&ruleset->lock);
>> > > +
>> > > +	return err;
>> > > +}
>> > > +
>> > > +int add_rule_net_service(struct landlock_ruleset *ruleset,
>> > 
>> > We should only export functions with a "landlock_" prefix, and "service"
>> > is now replaced with "port", which gives landlock_add_rule_net_port().
>> > 
>> > For consistency, we should also rename add_rule_path_beneath() into
>> > landlock_add_rule_path_beneath(), move it into fs.c, and merge
>> > landlock_append_fs_rule() into it (being careful to not move the related
>> > code to ease review). This change should be part of the "landlock:
>> > Refactor landlock_add_rule() syscall" patch. Please be careful to keep
>> > the other changes happening in other patches.
>> > 
>>   Should I still update prefix according your suggestions (keep
>> add_rule_net_service() in syscalls.c) in the next mail thread or keep it as
>> it is:
>>   https://lore.kernel.org/netdev/[e-mail]/
>> ????
> 
> No, the prefix notation is only useful for exported functions, just
> renamed it to add_rule_net_port() and make it static.

   Ok. Thanks!!
> 
>> > 
>> > > +			 const void __user *const rule_attr)
>> > > +{
>> > > +	struct landlock_net_port_attr net_port_attr;
>> > > +	int res;
>> > > +	access_mask_t mask, bind_access_mask;
>> > > +
>> > > +	/* Copies raw user space buffer. */
>> > > +	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
>> > 
>> > We should include <linux/uaccess.h> because of copy_from_user().
>> > 
>> > Same for landlock_add_rule_path_beneath().
> 
> Same as above, this is not relevant anymore.

   Got it. thanks.
> 
>> > 
>> > > +	if (res)
>> > > +		return -EFAULT;
>> > > +
>> > > +	/*
>> > > +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
>> > > +	 * are ignored by network actions.
>> > > +	 */
>> > > +	if (!net_port_attr.allowed_access)
>> > > +		return -ENOMSG;
>> > > +
>> > > +	/*
>> > > +	 * Checks that allowed_access matches the @ruleset constraints
>> > > +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
>> > > +	 */
>> > > +	mask = landlock_get_net_access_mask(ruleset, 0);
>> > > +	if ((net_port_attr.allowed_access | mask) != mask)
>> > > +		return -EINVAL;
>> > > +
>> > > +	/*
>> > > +	 * Denies inserting a rule with port 0 (for bind action) or
>> > > +	 * higher than 65535.
>> > > +	 */
>> > > +	bind_access_mask = net_port_attr.allowed_access &
>> > > +			   LANDLOCK_ACCESS_NET_BIND_TCP;
>> > > +	if (((net_port_attr.port == 0) &&
>> > > +	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||
>> > 
>> > For context about "port 0 binding" see
>> > https://lore.kernel.org/all/[e-mail]/
>> > 
>> > I previously said:
>> > > > > To say it another way, we should not allow to add a rule with port
>> > > > > 0 for
>> > > > > LANDLOCK_ACCESS_NET_BIND_TCP, but return -EINVAL in this case. This
>> > > > > limitation should be explained, documented and tested.
>> > 
>> > Thinking more about this port 0 for bind (and after an interesting
>> > discussion with Eric), it would be a mistake to forbid a rule to bind on
>> > port 0 because this is very useful for some network services, and
>> > because it would not be reasonable to have an LSM hook to control such
>> > "random ports". Instead we should document what using this value means
>> > (i.e. pick a dynamic available port in a range defined by the sysadmin)
>> > and highlight the fact that it is controlled with the
>> > /proc/sys/net/ipv4/ip_local_port_range sysctl, which is also used by
>> > IPv6.
>> > 
>> > We then need to test binding on port zero by getting the binded port
>> > (cf. getsockopt/getsockname) and checking that we can indeed connect to
>> > it.
>> 
>>   So like I understand refactoring will be like this:
>> 	1. Allow bind for zero port.
>> 	2. Update tests:
>> 		- add rule with port 0;
>> 		- bind "random" port;
>> 		- using getsockname to get binded port;
>> 		- connect to the socket using binded port;
>> 		
>>  Correct??
> 
> Yes. You can also extend this test to try binding to a lower port (e.g.
> 1024, value of srv0.port), not part of ip_local_port_range, which should
> then be denied.

   Ok. I will extend zero port tests with lower port value.
   Thanks.
> 
>> > 
>> > > +	    (net_port_attr.port > U16_MAX))
>> > > +		return -EINVAL;
>> > > +
>> > > +	/* Imports the new rule. */
>> > > +	return landlock_append_net_rule(ruleset, net_port_attr.port,
>> > > +					net_port_attr.allowed_access);
>> > > +}
>> > 
>> > > diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
>> > > index 1ede2b9a79b7..9bd0483c64d4 100644
>> > > --- a/security/landlock/ruleset.h
>> > > +++ b/security/landlock/ruleset.h
>> > > @@ -33,13 +33,16 @@
>> > >  typedef u16 access_mask_t;
>> > >  /* Makes sure all filesystem access rights can be stored. */
>> > >  static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS);
>> > > +/* Makes sure all network access rights can be stored. */
>> > > +static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET);
>> > >  /* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */
>> > >  static_assert(sizeof(unsigned long) >= sizeof(access_mask_t));
>> > > 
>> > >  /* Ruleset access masks. */
>> > > -typedef u16 access_masks_t;
>> > > +typedef u32 access_masks_t;
>> > >  /* Makes sure all ruleset access rights can be stored. */
>> > > -static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS);
>> > > +static_assert(BITS_PER_TYPE(access_masks_t) >=
>> > > +	      LANDLOCK_NUM_ACCESS_FS + LANDLOCK_NUM_ACCESS_NET);
>> > > 
>> > >  typedef u16 layer_mask_t;
>> > >  /* Makes sure all layers can be checked. */
>> > > @@ -84,6 +87,11 @@ enum landlock_key_type {
>> > >  	 * keys.
>> > >  	 */
>> > >  	LANDLOCK_KEY_INODE = 1,
>> > > +	/**
>> > > +	 * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's
>> > > +	 * node keys.
>> > > +	 */
>> > > +	LANDLOCK_KEY_NET_PORT = 2,
>> > 
>> > You don't need to specify "2".
>> 
>>   Ok. thanks.
>> > 
>> > 
>> > > diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
>> > > index 8a54e87dbb17..da6cbd0032ca 100644
>> > > --- a/security/landlock/syscalls.c
>> > > +++ b/security/landlock/syscalls.c
>> > > @@ -29,6 +29,7 @@
>> > >  #include "cred.h"
>> > >  #include "fs.h"
>> > >  #include "limits.h"
>> > > +#include "net.h"
>> > >  #include "ruleset.h"
>> > >  #include "setup.h"
>> > > 
>> > > @@ -74,7 +75,8 @@ static void build_check_abi(void)
>> > >  {
>> > >  	struct landlock_ruleset_attr ruleset_attr;
>> > >  	struct landlock_path_beneath_attr path_beneath_attr;
>> > > -	size_t ruleset_size, path_beneath_size;
>> > > +	struct landlock_net_port_attr net_port_attr;
>> > > +	size_t ruleset_size, path_beneath_size, net_service_size;
>> > 
>> > net_port_size
>> 
>>   right. will be fixed.
>> > .
> .

Konstantin Meskhidze (A) Oct. 10, 2023, 11:22 a.m. UTC | #12

10/10/2023 12:17 PM, Mickaël Salaün пишет:
> On Tue, Oct 10, 2023 at 05:20:45AM +0300, Konstantin Meskhidze (A) wrote:
>> 
>> 
>> 10/9/2023 5:12 PM, Mickaël Salaün пишет:
>> > On Mon, Oct 02, 2023 at 10:26:36PM +0200, Mickaël Salaün wrote:
>> > > Thanks for this new version Konstantin. I pushed this series, with minor
>> > > changes, to -next. So far, no warning. But it needs some changes, mostly
>> > > kernel-only, but also one with the handling of port 0 with bind (see my
>> > > review below).
>> > > 
>> > > On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
>> > > > This commit adds network rules support in the ruleset management
>> > > > helpers and the landlock_create_ruleset syscall.
>> > > > Refactor user space API to support network actions. Add new network
>> > > > access flags, network rule and network attributes. Increment Landlock
>> > > > ABI version. Expand access_masks_t to u32 to be sure network access
>> > > > rights can be stored. Implement socket_bind() and socket_connect()
>> > > > LSM hooks, which enables to restrict TCP socket binding and connection
>> > > > to specific ports.
>> > > > The new landlock_net_port_attr structure has two fields. The allowed_access
>> > > > field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
>> > > > the port value according to the allowed protocol. This field can
>> > > > take up to a 64-bit value [1] but the maximum value depends on the related
>> > > > protocol (e.g. 16-bit for TCP).
>> > > > > [1]
>> > > > https://lore.kernel.org/r/[e-mail]
>> > > > > Signed-off-by: Mickaël Salaün <[e-mail]>
>> > > > Signed-off-by: Konstantin Meskhidze <[e-mail]>
>> > > > ---
>> > > > > Changes since v11:
>> > > > * Replace dates with "2022-2023" in net.c/h files headers.
>> > > > * Removes WARN_ON_ONCE(!domain) in check_socket_access().
>> > > > * Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family).
>> > > > * Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT.
>> > > > * Renames landlock_net_service_attr to landlock_net_port_attr.
>> > > > * Defines two add_rule_net_service() functions according to
>> > > >   IS_ENABLED(CONFIG_INET) instead of changing the body of the only
>> > > >   function.
>> > > > * Adds af_family consistency check while handling AF_UNSPEC specifically.
>> > > > * Adds bind_access_mask in add_rule_net_service() to deny all rules with bind
>> > > >   action on port zero.
>> > > > * Minor fixes.
>> > > > * Refactors commit message.
>> > > > > Changes since v10:
>> > > > * Removes "packed" attribute.
>> > > > * Applies Mickaёl's patch with some refactoring.
>> > > > * Deletes get_port() and check_addrlen() helpers.
>> > > > * Refactors check_socket_access() by squashing get_port() and
>> > > >   check_addrlen() helpers into it.
>> > > > * Fixes commit message.
>> > > > > Changes since v9:
>> > > > * Changes UAPI port field to __u64.
>> > > > * Moves shared code into check_socket_access().
>> > > > * Adds get_raw_handled_net_accesses() and
>> > > >   get_current_net_domain() helpers.
>> > > > * Minor fixes.
>> > > > > Changes since v8:
>> > > > * Squashes commits.
>> > > > * Refactors commit message.
>> > > > * Changes UAPI port field to __be16.
>> > > > * Changes logic of bind/connect hooks with AF_UNSPEC families.
>> > > > * Adds address length checking.
>> > > > * Minor fixes.
>> > > > > Changes since v7:
>> > > > * Squashes commits.
>> > > > * Increments ABI version to 4.
>> > > > * Refactors commit message.
>> > > > * Minor fixes.
>> > > > > Changes since v6:
>> > > > * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
>> > > >   because it OR values.
>> > > > * Makes landlock_add_net_access_mask() more resilient incorrect values.
>> > > > * Refactors landlock_get_net_access_mask().
>> > > > * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
>> > > >   LANDLOCK_NUM_ACCESS_FS as value.
>> > > > * Updates access_masks_t to u32 to support network access actions.
>> > > > * Refactors landlock internal functions to support network actions with
>> > > >   landlock_key/key_type/id types.
>> > > > > Changes since v5:
>> > > > * Gets rid of partial revert from landlock_add_rule
>> > > > syscall.
>> > > > * Formats code with clang-format-14.
>> > > > > Changes since v4:
>> > > > * Refactors landlock_create_ruleset() - splits ruleset and
>> > > > masks checks.
>> > > > * Refactors landlock_create_ruleset() and landlock mask
>> > > > setters/getters to support two rule types.
>> > > > * Refactors landlock_add_rule syscall add_rule_path_beneath
>> > > > function by factoring out get_ruleset_from_fd() and
>> > > > landlock_put_ruleset().
>> > > > > Changes since v3:
>> > > > * Splits commit.
>> > > > * Adds network rule support for internal landlock functions.
>> > > > * Adds set_mask and get_mask for network.
>> > > > * Adds rb_root root_net_port.
>> > > > > ---
>> > > >  include/uapi/linux/landlock.h                |  47 ++++
>> > > >  security/landlock/Kconfig                    |   3 +-
>> > > >  security/landlock/Makefile                   |   2 +
>> > > >  security/landlock/limits.h                   |   5 +
>> > > >  security/landlock/net.c                      | 241 +++++++++++++++++++
>> > > >  security/landlock/net.h                      |  35 +++
>> > > >  security/landlock/ruleset.c                  |  62 ++++-
>> > > >  security/landlock/ruleset.h                  |  59 ++++-
>> > > >  security/landlock/setup.c                    |   2 +
>> > > >  security/landlock/syscalls.c                 |  33 ++-
>> > > >  tools/testing/selftests/landlock/base_test.c |   2 +-
>> > > >  11 files changed, 467 insertions(+), 24 deletions(-)
>> > > >  create mode 100644 security/landlock/net.c
>> > > >  create mode 100644 security/landlock/net.h
>> > > >
>> > 
>> > > > diff --git a/security/landlock/net.c b/security/landlock/net.c
>> > > > new file mode 100644
>> > > > index 000000000000..62b830653e25
>> > > > --- /dev/null
>> > > > +++ b/security/landlock/net.c
>> > > > @@ -0,0 +1,241 @@
>> > > > +// SPDX-License-Identifier: GPL-2.0-only
>> > > > +/*
>> > > > + * Landlock LSM - Network management and hooks
>> > > > + *
>> > > > + * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
>> > > > + * Copyright © 2022-2023 Microsoft Corporation
>> > > > + */
>> > > > +
>> > > > +#include <linux/in.h>
>> > > > +#include <linux/net.h>
>> > > > +#include <linux/socket.h>
>> > > > +#include <net/ipv6.h>
>> > > > +
>> > > > +#include "common.h"
>> > > > +#include "cred.h"
>> > > > +#include "limits.h"
>> > > > +#include "net.h"
>> > > > +#include "ruleset.h"
>> > > > +
>> > > > +int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
>> > > > +			     const u16 port, access_mask_t access_rights)
>> > > 
>> > > This function is only used in add_rule_net_service(), so it should not
>> > > be exported, and we can merge it (into landlock_add_rule_net_port).
>> > > 
>> > > > +{
>> > > > +	int err;
>> > > > +	const struct landlock_id id = {
>> > > > +		.key.data = (__force uintptr_t)htons(port),
>> > > > +		.type = LANDLOCK_KEY_NET_PORT,
>> > > > +	};
>> > > > +
>> > > > +	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
>> > > > +
>> > > > +	/* Transforms relative access rights to absolute ones. */
>> > > > +	access_rights |= LANDLOCK_MASK_ACCESS_NET &
>> > > > +			 ~landlock_get_net_access_mask(ruleset, 0);
>> > > > +
>> > > > +	mutex_lock(&ruleset->lock);
>> > > > +	err = landlock_insert_rule(ruleset, id, access_rights);
>> > > > +	mutex_unlock(&ruleset->lock);
>> > > > +
>> > > > +	return err;
>> > > > +}
>> > > > +
>> > > > +int add_rule_net_service(struct landlock_ruleset *ruleset,
>> > > 
>> > > We should only export functions with a "landlock_" prefix, and "service"
>> > > is now replaced with "port", which gives landlock_add_rule_net_port().
>> > > 
>> > > For consistency, we should also rename add_rule_path_beneath() into
>> > > landlock_add_rule_path_beneath(), move it into fs.c, and merge
>> > > landlock_append_fs_rule() into it (being careful to not move the related
>> > > code to ease review). This change should be part of the "landlock:
>> > > Refactor landlock_add_rule() syscall" patch. Please be careful to keep
>> > > the other changes happening in other patches.
>> > > 
>> > > 
>> > > > +			 const void __user *const rule_attr)
>> > > > +{
>> > > > +	struct landlock_net_port_attr net_port_attr;
>> > > > +	int res;
>> > > > +	access_mask_t mask, bind_access_mask;
>> > > > +
>> > > > +	/* Copies raw user space buffer. */
>> > > > +	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
>> > > 
>> > > We should include <linux/uaccess.h> because of copy_from_user().
>> > > 
>> > > Same for landlock_add_rule_path_beneath().
>> > > 
>> > > > +	if (res)
>> > > > +		return -EFAULT;
>> > > > +
>> > > > +	/*
>> > > > +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
>> > > > +	 * are ignored by network actions.
>> > > > +	 */
>> > > > +	if (!net_port_attr.allowed_access)
>> > > > +		return -ENOMSG;
>> > > > +
>> > > > +	/*
>> > > > +	 * Checks that allowed_access matches the @ruleset constraints
>> > > > +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
>> > > > +	 */
>> > > > +	mask = landlock_get_net_access_mask(ruleset, 0);
>> > > > +	if ((net_port_attr.allowed_access | mask) != mask)
>> > > > +		return -EINVAL;
>> > > > +
>> > > > +	/*
>> > > > +	 * Denies inserting a rule with port 0 (for bind action) or
>> > > > +	 * higher than 65535.
>> > > > +	 */
>> > > > +	bind_access_mask = net_port_attr.allowed_access &
>> > > > +			   LANDLOCK_ACCESS_NET_BIND_TCP;
>> > > > +	if (((net_port_attr.port == 0) &&
>> > > > +	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||
>> > > > +	    (net_port_attr.port > U16_MAX))
>> > > > +		return -EINVAL;
>> > > > +
>> > > > +	/* Imports the new rule. */
>> > > > +	return landlock_append_net_rule(ruleset, net_port_attr.port,
>> > > > +					net_port_attr.allowed_access);
>> > > > +}
>> > 
>> > Please ignore the above suggestions. Thinking more about this, let's
>> > keep the static add_rule_net_service() in syscalls.c, and only make the
>> > inline landlock_add_rule_net_service() return -EAFNOSUPPORT (which is
>> > already the case with this patch when CONFIG_INET is not set). This will
>> > slightly change the current semantic but enable to check all the
>> > syscalls arguments even if CONFIG_INET is not set, which is a good thing
>> > (and should be reflected in tests). It is better to group all the code
>> > handling user space memory copying and ABI specificities in the
>> > syscalls.c file. This approach is simpler, it will avoid the exported
>> > function issues (e.g. add_rule_net_service), and it will not require
>> > more changes to the fs.[ch] files.
>> > .
>>   Ok.Will be moved back to syscalls.c.
>>   What about renaming to add_rule_net_service()->add_rule_net_port() ???
> 
> Yes please rename it, there should be no mention of "net_service"
> anymore.

   Got it. Thanks.
> .

Konstantin Meskhidze (A) Oct. 11, 2023, 1:53 a.m. UTC | #13

10/2/2023 11:26 PM, Mickaël Salaün пишет:
> Thanks for this new version Konstantin. I pushed this series, with minor
> changes, to -next. So far, no warning. But it needs some changes, mostly
> kernel-only, but also one with the handling of port 0 with bind (see my
> review below).
> 
> On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
>> This commit adds network rules support in the ruleset management
>> helpers and the landlock_create_ruleset syscall.
>> Refactor user space API to support network actions. Add new network
>> access flags, network rule and network attributes. Increment Landlock
>> ABI version. Expand access_masks_t to u32 to be sure network access
>> rights can be stored. Implement socket_bind() and socket_connect()
>> LSM hooks, which enables to restrict TCP socket binding and connection
>> to specific ports.
>> The new landlock_net_port_attr structure has two fields. The allowed_access
>> field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
>> the port value according to the allowed protocol. This field can
>> take up to a 64-bit value [1] but the maximum value depends on the related
>> protocol (e.g. 16-bit for TCP).
>> 
>> [1]
>> https://lore.kernel.org/r/[e-mail]
>> 
>> Signed-off-by: Mickaël Salaün <[e-mail]>
>> Signed-off-by: Konstantin Meskhidze <[e-mail]>
>> ---
>> 
>> Changes since v11:
>> * Replace dates with "2022-2023" in net.c/h files headers.
>> * Removes WARN_ON_ONCE(!domain) in check_socket_access().
>> * Using "typeof(*address)" instead of offsetofend(struct sockaddr, sa_family).
>> * Renames LANDLOCK_RULE_NET_SERVICE to LANDLOCK_RULE_NET_PORT.
>> * Renames landlock_net_service_attr to landlock_net_port_attr.
>> * Defines two add_rule_net_service() functions according to
>>   IS_ENABLED(CONFIG_INET) instead of changing the body of the only
>>   function.
>> * Adds af_family consistency check while handling AF_UNSPEC specifically.
>> * Adds bind_access_mask in add_rule_net_service() to deny all rules with bind
>>   action on port zero.
>> * Minor fixes.
>> * Refactors commit message.
>> 
>> Changes since v10:
>> * Removes "packed" attribute.
>> * Applies Mickaёl's patch with some refactoring.
>> * Deletes get_port() and check_addrlen() helpers.
>> * Refactors check_socket_access() by squashing get_port() and
>>   check_addrlen() helpers into it.
>> * Fixes commit message.
>> 
>> Changes since v9:
>> * Changes UAPI port field to __u64.
>> * Moves shared code into check_socket_access().
>> * Adds get_raw_handled_net_accesses() and
>>   get_current_net_domain() helpers.
>> * Minor fixes.
>> 
>> Changes since v8:
>> * Squashes commits.
>> * Refactors commit message.
>> * Changes UAPI port field to __be16.
>> * Changes logic of bind/connect hooks with AF_UNSPEC families.
>> * Adds address length checking.
>> * Minor fixes.
>> 
>> Changes since v7:
>> * Squashes commits.
>> * Increments ABI version to 4.
>> * Refactors commit message.
>> * Minor fixes.
>> 
>> Changes since v6:
>> * Renames landlock_set_net_access_mask() to landlock_add_net_access_mask()
>>   because it OR values.
>> * Makes landlock_add_net_access_mask() more resilient incorrect values.
>> * Refactors landlock_get_net_access_mask().
>> * Renames LANDLOCK_MASK_SHIFT_NET to LANDLOCK_SHIFT_ACCESS_NET and use
>>   LANDLOCK_NUM_ACCESS_FS as value.
>> * Updates access_masks_t to u32 to support network access actions.
>> * Refactors landlock internal functions to support network actions with
>>   landlock_key/key_type/id types.
>> 
>> Changes since v5:
>> * Gets rid of partial revert from landlock_add_rule
>> syscall.
>> * Formats code with clang-format-14.
>> 
>> Changes since v4:
>> * Refactors landlock_create_ruleset() - splits ruleset and
>> masks checks.
>> * Refactors landlock_create_ruleset() and landlock mask
>> setters/getters to support two rule types.
>> * Refactors landlock_add_rule syscall add_rule_path_beneath
>> function by factoring out get_ruleset_from_fd() and
>> landlock_put_ruleset().
>> 
>> Changes since v3:
>> * Splits commit.
>> * Adds network rule support for internal landlock functions.
>> * Adds set_mask and get_mask for network.
>> * Adds rb_root root_net_port.
>> 
>> ---
>>  include/uapi/linux/landlock.h                |  47 ++++
>>  security/landlock/Kconfig                    |   3 +-
>>  security/landlock/Makefile                   |   2 +
>>  security/landlock/limits.h                   |   5 +
>>  security/landlock/net.c                      | 241 +++++++++++++++++++
>>  security/landlock/net.h                      |  35 +++
>>  security/landlock/ruleset.c                  |  62 ++++-
>>  security/landlock/ruleset.h                  |  59 ++++-
>>  security/landlock/setup.c                    |   2 +
>>  security/landlock/syscalls.c                 |  33 ++-
>>  tools/testing/selftests/landlock/base_test.c |   2 +-
>>  11 files changed, 467 insertions(+), 24 deletions(-)
>>  create mode 100644 security/landlock/net.c
>>  create mode 100644 security/landlock/net.h
>> 
>> diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
>> index 81d09ef9aa50..3b8400e8a4d9 100644
>> --- a/include/uapi/linux/landlock.h
>> +++ b/include/uapi/linux/landlock.h
>> @@ -31,6 +31,12 @@ struct landlock_ruleset_attr {
>>  	 * this access right.
>>  	 */
>>  	__u64 handled_access_fs;
>> +	/**
>> +	 * @handled_access_net: Bitmask of actions (cf. `Network flags`_)
>> +	 * that is handled by this ruleset and should then be forbidden if no
>> +	 * rule explicitly allow them.
>> +	 */
>> +	__u64 handled_access_net;
>>  };
>> 
>>  /*
>> @@ -54,6 +60,11 @@ enum landlock_rule_type {
>>  	 * landlock_path_beneath_attr .
>>  	 */
>>  	LANDLOCK_RULE_PATH_BENEATH = 1,
>> +	/**
>> +	 * @LANDLOCK_RULE_NET_PORT: Type of a &struct
>> +	 * landlock_net_port_attr .
>> +	 */
>> +	LANDLOCK_RULE_NET_PORT = 2,
>>  };
>> 
>>  /**
>> @@ -79,6 +90,23 @@ struct landlock_path_beneath_attr {
>>  	 */
>>  } __attribute__((packed));
>> 
>> +/**
>> + * struct landlock_net_port_attr - Network service definition
> 
> "Network port definition"
> 
> 
>> diff --git a/security/landlock/Kconfig b/security/landlock/Kconfig
>> index c1e862a38410..10c099097533 100644
>> --- a/security/landlock/Kconfig
>> +++ b/security/landlock/Kconfig
>> @@ -2,7 +2,8 @@
>> 
>>  config SECURITY_LANDLOCK
>>  	bool "Landlock support"
>> -	depends on SECURITY
>> +	depends on SECURITY && !ARCH_EPHEMERAL_INODES
> 
> !ARCH_EPHEMERAL_INODES is definitely gone now.
> 
>> +	select SECURITY_NETWORK
>>  	select SECURITY_PATH
>>  	help
>>  	  Landlock is a sandboxing mechanism that enables processes to restrict
>> diff --git a/security/landlock/Makefile b/security/landlock/Makefile
>> index 7bbd2f413b3e..53d3c92ae22e 100644
>> --- a/security/landlock/Makefile
>> +++ b/security/landlock/Makefile
>> @@ -2,3 +2,5 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o
>> 
>>  landlock-y := setup.o syscalls.o object.o ruleset.o \
>>  	cred.o ptrace.o fs.o
>> +
>> +landlock-$(CONFIG_INET) += net.o
>> \ No newline at end of file
>> diff --git a/security/landlock/limits.h b/security/landlock/limits.h
>> index bafb3b8dc677..93c9c6f91556 100644
>> --- a/security/landlock/limits.h
>> +++ b/security/landlock/limits.h
>> @@ -23,6 +23,11 @@
>>  #define LANDLOCK_NUM_ACCESS_FS		__const_hweight64(LANDLOCK_MASK_ACCESS_FS)
>>  #define LANDLOCK_SHIFT_ACCESS_FS	0
>> 
>> +#define LANDLOCK_LAST_ACCESS_NET	LANDLOCK_ACCESS_NET_CONNECT_TCP
>> +#define LANDLOCK_MASK_ACCESS_NET	((LANDLOCK_LAST_ACCESS_NET << 1) - 1)
>> +#define LANDLOCK_NUM_ACCESS_NET		__const_hweight64(LANDLOCK_MASK_ACCESS_NET)
>> +#define LANDLOCK_SHIFT_ACCESS_NET	LANDLOCK_NUM_ACCESS_FS
>> +
>>  /* clang-format on */
>> 
>>  #endif /* _SECURITY_LANDLOCK_LIMITS_H */
>> diff --git a/security/landlock/net.c b/security/landlock/net.c
>> new file mode 100644
>> index 000000000000..62b830653e25
>> --- /dev/null
>> +++ b/security/landlock/net.c
>> @@ -0,0 +1,241 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Landlock LSM - Network management and hooks
>> + *
>> + * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
>> + * Copyright © 2022-2023 Microsoft Corporation
>> + */
>> +
>> +#include <linux/in.h>
>> +#include <linux/net.h>
>> +#include <linux/socket.h>
>> +#include <net/ipv6.h>
>> +
>> +#include "common.h"
>> +#include "cred.h"
>> +#include "limits.h"
>> +#include "net.h"
>> +#include "ruleset.h"
>> +
>> +int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
>> +			     const u16 port, access_mask_t access_rights)
> 
> This function is only used in add_rule_net_service(), so it should not
> be exported, and we can merge it (into landlock_add_rule_net_port).
> 
>> +{
>> +	int err;
>> +	const struct landlock_id id = {
>> +		.key.data = (__force uintptr_t)htons(port),
>> +		.type = LANDLOCK_KEY_NET_PORT,
>> +	};
>> +
>> +	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
>> +
>> +	/* Transforms relative access rights to absolute ones. */
>> +	access_rights |= LANDLOCK_MASK_ACCESS_NET &
>> +			 ~landlock_get_net_access_mask(ruleset, 0);
>> +
>> +	mutex_lock(&ruleset->lock);
>> +	err = landlock_insert_rule(ruleset, id, access_rights);
>> +	mutex_unlock(&ruleset->lock);
>> +
>> +	return err;
>> +}
>> +
>> +int add_rule_net_service(struct landlock_ruleset *ruleset,
> 
> We should only export functions with a "landlock_" prefix, and "service"
> is now replaced with "port", which gives landlock_add_rule_net_port().
> 
> For consistency, we should also rename add_rule_path_beneath() into
> landlock_add_rule_path_beneath(), move it into fs.c, and merge
> landlock_append_fs_rule() into it (being careful to not move the related
> code to ease review). This change should be part of the "landlock:
> Refactor landlock_add_rule() syscall" patch. Please be careful to keep
> the other changes happening in other patches.
> 
> 
>> +			 const void __user *const rule_attr)
>> +{
>> +	struct landlock_net_port_attr net_port_attr;
>> +	int res;
>> +	access_mask_t mask, bind_access_mask;
>> +
>> +	/* Copies raw user space buffer. */
>> +	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
> 
> We should include <linux/uaccess.h> because of copy_from_user().
> 
> Same for landlock_add_rule_path_beneath().
> 
>> +	if (res)
>> +		return -EFAULT;
>> +
>> +	/*
>> +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
>> +	 * are ignored by network actions.
>> +	 */
>> +	if (!net_port_attr.allowed_access)
>> +		return -ENOMSG;
>> +
>> +	/*
>> +	 * Checks that allowed_access matches the @ruleset constraints
>> +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
>> +	 */
>> +	mask = landlock_get_net_access_mask(ruleset, 0);
>> +	if ((net_port_attr.allowed_access | mask) != mask)
>> +		return -EINVAL;
>> +
>> +	/*
>> +	 * Denies inserting a rule with port 0 (for bind action) or
>> +	 * higher than 65535.
>> +	 */
>> +	bind_access_mask = net_port_attr.allowed_access &
>> +			   LANDLOCK_ACCESS_NET_BIND_TCP;
>> +	if (((net_port_attr.port == 0) &&
>> +	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||
> 
> For context about "port 0 binding" see
> https://lore.kernel.org/all/[e-mail]/
> 
> I previously said:
>>> > To say it another way, we should not allow to add a rule with port
>>> > 0 for
>>> > LANDLOCK_ACCESS_NET_BIND_TCP, but return -EINVAL in this case. This
>>> > limitation should be explained, documented and tested.
> 
> Thinking more about this port 0 for bind (and after an interesting
> discussion with Eric), it would be a mistake to forbid a rule to bind on
> port 0 because this is very useful for some network services, and
> because it would not be reasonable to have an LSM hook to control such
> "random ports". Instead we should document what using this value means
> (i.e. pick a dynamic available port in a range defined by the sysadmin)
> and highlight the fact that it is controlled with the
> /proc/sys/net/ipv4/ip_local_port_range sysctl, which is also used by
> IPv6.

   Hi Mickaёl.
   I also wonder which part of documentation (landlock.rst) we should 
include zero port description in?
> 
> We then need to test binding on port zero by getting the binded port
> (cf. getsockopt/getsockname) and checking that we can indeed connect to
> it.
> 
>> +	    (net_port_attr.port > U16_MAX))
>> +		return -EINVAL;
>> +
>> +	/* Imports the new rule. */
>> +	return landlock_append_net_rule(ruleset, net_port_attr.port,
>> +					net_port_attr.allowed_access);
>> +}
> 
>> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
>> index 1ede2b9a79b7..9bd0483c64d4 100644
>> --- a/security/landlock/ruleset.h
>> +++ b/security/landlock/ruleset.h
>> @@ -33,13 +33,16 @@
>>  typedef u16 access_mask_t;
>>  /* Makes sure all filesystem access rights can be stored. */
>>  static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS);
>> +/* Makes sure all network access rights can be stored. */
>> +static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET);
>>  /* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */
>>  static_assert(sizeof(unsigned long) >= sizeof(access_mask_t));
>> 
>>  /* Ruleset access masks. */
>> -typedef u16 access_masks_t;
>> +typedef u32 access_masks_t;
>>  /* Makes sure all ruleset access rights can be stored. */
>> -static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS);
>> +static_assert(BITS_PER_TYPE(access_masks_t) >=
>> +	      LANDLOCK_NUM_ACCESS_FS + LANDLOCK_NUM_ACCESS_NET);
>> 
>>  typedef u16 layer_mask_t;
>>  /* Makes sure all layers can be checked. */
>> @@ -84,6 +87,11 @@ enum landlock_key_type {
>>  	 * keys.
>>  	 */
>>  	LANDLOCK_KEY_INODE = 1,
>> +	/**
>> +	 * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's
>> +	 * node keys.
>> +	 */
>> +	LANDLOCK_KEY_NET_PORT = 2,
> 
> You don't need to specify "2".
> 
> 
>> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
>> index 8a54e87dbb17..da6cbd0032ca 100644
>> --- a/security/landlock/syscalls.c
>> +++ b/security/landlock/syscalls.c
>> @@ -29,6 +29,7 @@
>>  #include "cred.h"
>>  #include "fs.h"
>>  #include "limits.h"
>> +#include "net.h"
>>  #include "ruleset.h"
>>  #include "setup.h"
>> 
>> @@ -74,7 +75,8 @@ static void build_check_abi(void)
>>  {
>>  	struct landlock_ruleset_attr ruleset_attr;
>>  	struct landlock_path_beneath_attr path_beneath_attr;
>> -	size_t ruleset_size, path_beneath_size;
>> +	struct landlock_net_port_attr net_port_attr;
>> +	size_t ruleset_size, path_beneath_size, net_service_size;
> 
> net_port_size
> .

Mickaël Salaün Oct. 11, 2023, 4:02 p.m. UTC | #14

On Wed, Oct 11, 2023 at 04:53:57AM +0300, Konstantin Meskhidze (A) wrote:
> 
> 
> 10/2/2023 11:26 PM, Mickaël Salaün пишет:
> > Thanks for this new version Konstantin. I pushed this series, with minor
> > changes, to -next. So far, no warning. But it needs some changes, mostly
> > kernel-only, but also one with the handling of port 0 with bind (see my
> > review below).
> > 
> > On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
> > > This commit adds network rules support in the ruleset management
> > > helpers and the landlock_create_ruleset syscall.
> > > Refactor user space API to support network actions. Add new network
> > > access flags, network rule and network attributes. Increment Landlock
> > > ABI version. Expand access_masks_t to u32 to be sure network access
> > > rights can be stored. Implement socket_bind() and socket_connect()
> > > LSM hooks, which enables to restrict TCP socket binding and connection
> > > to specific ports.
> > > The new landlock_net_port_attr structure has two fields. The allowed_access
> > > field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
> > > the port value according to the allowed protocol. This field can
> > > take up to a 64-bit value [1] but the maximum value depends on the related
> > > protocol (e.g. 16-bit for TCP).
> > > 
> > > [1]
> > > https://lore.kernel.org/r/[e-mail]
> > > 
> > > Signed-off-by: Mickaël Salaün <[e-mail]>
> > > Signed-off-by: Konstantin Meskhidze <[e-mail]>
> > > ---
> > > 

> > > +int add_rule_net_service(struct landlock_ruleset *ruleset,
> > 
> > We should only export functions with a "landlock_" prefix, and "service"
> > is now replaced with "port", which gives landlock_add_rule_net_port().
> > 
> > For consistency, we should also rename add_rule_path_beneath() into
> > landlock_add_rule_path_beneath(), move it into fs.c, and merge
> > landlock_append_fs_rule() into it (being careful to not move the related
> > code to ease review). This change should be part of the "landlock:
> > Refactor landlock_add_rule() syscall" patch. Please be careful to keep
> > the other changes happening in other patches.
> > 
> > 
> > > +			 const void __user *const rule_attr)
> > > +{
> > > +	struct landlock_net_port_attr net_port_attr;
> > > +	int res;
> > > +	access_mask_t mask, bind_access_mask;
> > > +
> > > +	/* Copies raw user space buffer. */
> > > +	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
> > 
> > We should include <linux/uaccess.h> because of copy_from_user().
> > 
> > Same for landlock_add_rule_path_beneath().
> > 
> > > +	if (res)
> > > +		return -EFAULT;
> > > +
> > > +	/*
> > > +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
> > > +	 * are ignored by network actions.
> > > +	 */
> > > +	if (!net_port_attr.allowed_access)
> > > +		return -ENOMSG;
> > > +
> > > +	/*
> > > +	 * Checks that allowed_access matches the @ruleset constraints
> > > +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
> > > +	 */
> > > +	mask = landlock_get_net_access_mask(ruleset, 0);
> > > +	if ((net_port_attr.allowed_access | mask) != mask)
> > > +		return -EINVAL;
> > > +
> > > +	/*
> > > +	 * Denies inserting a rule with port 0 (for bind action) or
> > > +	 * higher than 65535.
> > > +	 */
> > > +	bind_access_mask = net_port_attr.allowed_access &
> > > +			   LANDLOCK_ACCESS_NET_BIND_TCP;
> > > +	if (((net_port_attr.port == 0) &&
> > > +	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||
> > 
> > For context about "port 0 binding" see
> > https://lore.kernel.org/all/[e-mail]/
> > 
> > I previously said:
> > > > > To say it another way, we should not allow to add a rule with port
> > > > > 0 for
> > > > > LANDLOCK_ACCESS_NET_BIND_TCP, but return -EINVAL in this case. This
> > > > > limitation should be explained, documented and tested.
> > 
> > Thinking more about this port 0 for bind (and after an interesting
> > discussion with Eric), it would be a mistake to forbid a rule to bind on
> > port 0 because this is very useful for some network services, and
> > because it would not be reasonable to have an LSM hook to control such
> > "random ports". Instead we should document what using this value means
> > (i.e. pick a dynamic available port in a range defined by the sysadmin)
> > and highlight the fact that it is controlled with the
> > /proc/sys/net/ipv4/ip_local_port_range sysctl, which is also used by
> > IPv6.
> 
>   Hi Mickaёl.
>   I also wonder which part of documentation (landlock.rst) we should include
> zero port description in?

This documentation should be in the struct landlock_net_port_attr's @port
description, which will then be part of the generated documentation.


> > 
> > We then need to test binding on port zero by getting the binded port
> > (cf. getsockopt/getsockname) and checking that we can indeed connect to
> > it.
> > 
> > > +	    (net_port_attr.port > U16_MAX))
> > > +		return -EINVAL;
> > > +
> > > +	/* Imports the new rule. */
> > > +	return landlock_append_net_rule(ruleset, net_port_attr.port,
> > > +					net_port_attr.allowed_access);
> > > +}

Konstantin Meskhidze (A) Oct. 11, 2023, 4:04 p.m. UTC | #15

10/11/2023 7:02 PM, Mickaël Salaün пишет:
> On Wed, Oct 11, 2023 at 04:53:57AM +0300, Konstantin Meskhidze (A) wrote:
>> 
>> 
>> 10/2/2023 11:26 PM, Mickaël Salaün пишет:
>> > Thanks for this new version Konstantin. I pushed this series, with minor
>> > changes, to -next. So far, no warning. But it needs some changes, mostly
>> > kernel-only, but also one with the handling of port 0 with bind (see my
>> > review below).
>> > 
>> > On Wed, Sep 20, 2023 at 05:26:36PM +0800, Konstantin Meskhidze wrote:
>> > > This commit adds network rules support in the ruleset management
>> > > helpers and the landlock_create_ruleset syscall.
>> > > Refactor user space API to support network actions. Add new network
>> > > access flags, network rule and network attributes. Increment Landlock
>> > > ABI version. Expand access_masks_t to u32 to be sure network access
>> > > rights can be stored. Implement socket_bind() and socket_connect()
>> > > LSM hooks, which enables to restrict TCP socket binding and connection
>> > > to specific ports.
>> > > The new landlock_net_port_attr structure has two fields. The allowed_access
>> > > field contains the LANDLOCK_ACCESS_NET_* rights. The port field contains
>> > > the port value according to the allowed protocol. This field can
>> > > take up to a 64-bit value [1] but the maximum value depends on the related
>> > > protocol (e.g. 16-bit for TCP).
>> > > 
>> > > [1]
>> > > https://lore.kernel.org/r/[e-mail]
>> > > 
>> > > Signed-off-by: Mickaël Salaün <[e-mail]>
>> > > Signed-off-by: Konstantin Meskhidze <[e-mail]>
>> > > ---
>> > > 
> 
>> > > +int add_rule_net_service(struct landlock_ruleset *ruleset,
>> > 
>> > We should only export functions with a "landlock_" prefix, and "service"
>> > is now replaced with "port", which gives landlock_add_rule_net_port().
>> > 
>> > For consistency, we should also rename add_rule_path_beneath() into
>> > landlock_add_rule_path_beneath(), move it into fs.c, and merge
>> > landlock_append_fs_rule() into it (being careful to not move the related
>> > code to ease review). This change should be part of the "landlock:
>> > Refactor landlock_add_rule() syscall" patch. Please be careful to keep
>> > the other changes happening in other patches.
>> > 
>> > 
>> > > +			 const void __user *const rule_attr)
>> > > +{
>> > > +	struct landlock_net_port_attr net_port_attr;
>> > > +	int res;
>> > > +	access_mask_t mask, bind_access_mask;
>> > > +
>> > > +	/* Copies raw user space buffer. */
>> > > +	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
>> > 
>> > We should include <linux/uaccess.h> because of copy_from_user().
>> > 
>> > Same for landlock_add_rule_path_beneath().
>> > 
>> > > +	if (res)
>> > > +		return -EFAULT;
>> > > +
>> > > +	/*
>> > > +	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
>> > > +	 * are ignored by network actions.
>> > > +	 */
>> > > +	if (!net_port_attr.allowed_access)
>> > > +		return -ENOMSG;
>> > > +
>> > > +	/*
>> > > +	 * Checks that allowed_access matches the @ruleset constraints
>> > > +	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
>> > > +	 */
>> > > +	mask = landlock_get_net_access_mask(ruleset, 0);
>> > > +	if ((net_port_attr.allowed_access | mask) != mask)
>> > > +		return -EINVAL;
>> > > +
>> > > +	/*
>> > > +	 * Denies inserting a rule with port 0 (for bind action) or
>> > > +	 * higher than 65535.
>> > > +	 */
>> > > +	bind_access_mask = net_port_attr.allowed_access &
>> > > +			   LANDLOCK_ACCESS_NET_BIND_TCP;
>> > > +	if (((net_port_attr.port == 0) &&
>> > > +	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||
>> > 
>> > For context about "port 0 binding" see
>> > https://lore.kernel.org/all/[e-mail]/
>> > 
>> > I previously said:
>> > > > > To say it another way, we should not allow to add a rule with port
>> > > > > 0 for
>> > > > > LANDLOCK_ACCESS_NET_BIND_TCP, but return -EINVAL in this case. This
>> > > > > limitation should be explained, documented and tested.
>> > 
>> > Thinking more about this port 0 for bind (and after an interesting
>> > discussion with Eric), it would be a mistake to forbid a rule to bind on
>> > port 0 because this is very useful for some network services, and
>> > because it would not be reasonable to have an LSM hook to control such
>> > "random ports". Instead we should document what using this value means
>> > (i.e. pick a dynamic available port in a range defined by the sysadmin)
>> > and highlight the fact that it is controlled with the
>> > /proc/sys/net/ipv4/ip_local_port_range sysctl, which is also used by
>> > IPv6.
>> 
>>   Hi Mickaёl.
>>   I also wonder which part of documentation (landlock.rst) we should include
>> zero port description in?
> 
> This documentation should be in the struct landlock_net_port_attr's @port
> description, which will then be part of the generated documentation.
> 
   Got it.
   Thanks.
> 
>> > 
>> > We then need to test binding on port zero by getting the binded port
>> > (cf. getsockopt/getsockname) and checking that we can indeed connect to
>> > it.
>> > 
>> > > +	    (net_port_attr.port > U16_MAX))
>> > > +		return -EINVAL;
>> > > +
>> > > +	/* Imports the new rule. */
>> > > +	return landlock_append_net_rule(ruleset, net_port_attr.port,
>> > > +					net_port_attr.allowed_access);
>> > > +}
> .

Patch

diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h
index 81d09ef9aa50..3b8400e8a4d9 100644
--- a/include/uapi/linux/landlock.h
+++ b/include/uapi/linux/landlock.h
@@ -31,6 +31,12 @@  struct landlock_ruleset_attr {
 	 * this access right.
 	 */
 	__u64 handled_access_fs;
+	/**
+	 * @handled_access_net: Bitmask of actions (cf. `Network flags`_)
+	 * that is handled by this ruleset and should then be forbidden if no
+	 * rule explicitly allow them.
+	 */
+	__u64 handled_access_net;
 };

 /*
@@ -54,6 +60,11 @@  enum landlock_rule_type {
 	 * landlock_path_beneath_attr .
 	 */
 	LANDLOCK_RULE_PATH_BENEATH = 1,
+	/**
+	 * @LANDLOCK_RULE_NET_PORT: Type of a &struct
+	 * landlock_net_port_attr .
+	 */
+	LANDLOCK_RULE_NET_PORT = 2,
 };

 /**
@@ -79,6 +90,23 @@  struct landlock_path_beneath_attr {
 	 */
 } __attribute__((packed));

+/**
+ * struct landlock_net_port_attr - Network service definition
+ *
+ * Argument of sys_landlock_add_rule().
+ */
+struct landlock_net_port_attr {
+	/**
+	 * @allowed_access: Bitmask of allowed access network for a port
+	 * (cf. `Network flags`_).
+	 */
+	__u64 allowed_access;
+	/**
+	 * @port: Network port.
+	 */
+	__u64 port;
+};
+
 /**
  * DOC: fs_access
  *
@@ -189,4 +217,23 @@  struct landlock_path_beneath_attr {
 #define LANDLOCK_ACCESS_FS_TRUNCATE			(1ULL << 14)
 /* clang-format on */

+/**
+ * DOC: net_access
+ *
+ * Network flags
+ * ~~~~~~~~~~~~~~~~
+ *
+ * These flags enable to restrict a sandboxed process to a set of network
+ * actions.
+ *
+ * TCP sockets with allowed actions:
+ *
+ * - %LANDLOCK_ACCESS_NET_BIND_TCP: Bind a TCP socket to a local port.
+ * - %LANDLOCK_ACCESS_NET_CONNECT_TCP: Connect an active TCP socket to
+ *   a remote port.
+ */
+/* clang-format off */
+#define LANDLOCK_ACCESS_NET_BIND_TCP			(1ULL << 0)
+#define LANDLOCK_ACCESS_NET_CONNECT_TCP			(1ULL << 1)
+/* clang-format on */
 #endif /* _UAPI_LINUX_LANDLOCK_H */
diff --git a/security/landlock/Kconfig b/security/landlock/Kconfig
index c1e862a38410..10c099097533 100644
--- a/security/landlock/Kconfig
+++ b/security/landlock/Kconfig
@@ -2,7 +2,8 @@ 

 config SECURITY_LANDLOCK
 	bool "Landlock support"
-	depends on SECURITY
+	depends on SECURITY && !ARCH_EPHEMERAL_INODES
+	select SECURITY_NETWORK
 	select SECURITY_PATH
 	help
 	  Landlock is a sandboxing mechanism that enables processes to restrict
diff --git a/security/landlock/Makefile b/security/landlock/Makefile
index 7bbd2f413b3e..53d3c92ae22e 100644
--- a/security/landlock/Makefile
+++ b/security/landlock/Makefile
@@ -2,3 +2,5 @@  obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o

 landlock-y := setup.o syscalls.o object.o ruleset.o \
 	cred.o ptrace.o fs.o
+
+landlock-$(CONFIG_INET) += net.o
\ No newline at end of file
diff --git a/security/landlock/limits.h b/security/landlock/limits.h
index bafb3b8dc677..93c9c6f91556 100644
--- a/security/landlock/limits.h
+++ b/security/landlock/limits.h
@@ -23,6 +23,11 @@ 
 #define LANDLOCK_NUM_ACCESS_FS		__const_hweight64(LANDLOCK_MASK_ACCESS_FS)
 #define LANDLOCK_SHIFT_ACCESS_FS	0

+#define LANDLOCK_LAST_ACCESS_NET	LANDLOCK_ACCESS_NET_CONNECT_TCP
+#define LANDLOCK_MASK_ACCESS_NET	((LANDLOCK_LAST_ACCESS_NET << 1) - 1)
+#define LANDLOCK_NUM_ACCESS_NET		__const_hweight64(LANDLOCK_MASK_ACCESS_NET)
+#define LANDLOCK_SHIFT_ACCESS_NET	LANDLOCK_NUM_ACCESS_FS
+
 /* clang-format on */

 #endif /* _SECURITY_LANDLOCK_LIMITS_H */
diff --git a/security/landlock/net.c b/security/landlock/net.c
new file mode 100644
index 000000000000..62b830653e25
--- /dev/null
+++ b/security/landlock/net.c
@@ -0,0 +1,241 @@ 
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Landlock LSM - Network management and hooks
+ *
+ * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
+ * Copyright © 2022-2023 Microsoft Corporation
+ */
+
+#include <linux/in.h>
+#include <linux/net.h>
+#include <linux/socket.h>
+#include <net/ipv6.h>
+
+#include "common.h"
+#include "cred.h"
+#include "limits.h"
+#include "net.h"
+#include "ruleset.h"
+
+int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
+			     const u16 port, access_mask_t access_rights)
+{
+	int err;
+	const struct landlock_id id = {
+		.key.data = (__force uintptr_t)htons(port),
+		.type = LANDLOCK_KEY_NET_PORT,
+	};
+
+	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
+
+	/* Transforms relative access rights to absolute ones. */
+	access_rights |= LANDLOCK_MASK_ACCESS_NET &
+			 ~landlock_get_net_access_mask(ruleset, 0);
+
+	mutex_lock(&ruleset->lock);
+	err = landlock_insert_rule(ruleset, id, access_rights);
+	mutex_unlock(&ruleset->lock);
+
+	return err;
+}
+
+int add_rule_net_service(struct landlock_ruleset *ruleset,
+			 const void __user *const rule_attr)
+{
+	struct landlock_net_port_attr net_port_attr;
+	int res;
+	access_mask_t mask, bind_access_mask;
+
+	/* Copies raw user space buffer. */
+	res = copy_from_user(&net_port_attr, rule_attr, sizeof(net_port_attr));
+	if (res)
+		return -EFAULT;
+
+	/*
+	 * Informs about useless rule: empty allowed_access (i.e. deny rules)
+	 * are ignored by network actions.
+	 */
+	if (!net_port_attr.allowed_access)
+		return -ENOMSG;
+
+	/*
+	 * Checks that allowed_access matches the @ruleset constraints
+	 * (ruleset->access_masks[0] is automatically upgraded to 64-bits).
+	 */
+	mask = landlock_get_net_access_mask(ruleset, 0);
+	if ((net_port_attr.allowed_access | mask) != mask)
+		return -EINVAL;
+
+	/*
+	 * Denies inserting a rule with port 0 (for bind action) or
+	 * higher than 65535.
+	 */
+	bind_access_mask = net_port_attr.allowed_access &
+			   LANDLOCK_ACCESS_NET_BIND_TCP;
+	if (((net_port_attr.port == 0) &&
+	     (bind_access_mask == LANDLOCK_ACCESS_NET_BIND_TCP)) ||
+	    (net_port_attr.port > U16_MAX))
+		return -EINVAL;
+
+	/* Imports the new rule. */
+	return landlock_append_net_rule(ruleset, net_port_attr.port,
+					net_port_attr.allowed_access);
+}
+
+static access_mask_t
+get_raw_handled_net_accesses(const struct landlock_ruleset *const domain)
+{
+	access_mask_t access_dom = 0;
+	size_t layer_level;
+
+	for (layer_level = 0; layer_level < domain->num_layers; layer_level++)
+		access_dom |= landlock_get_net_access_mask(domain, layer_level);
+	return access_dom;
+}
+
+static const struct landlock_ruleset *get_current_net_domain(void)
+{
+	const struct landlock_ruleset *const dom =
+		landlock_get_current_domain();
+
+	if (!dom || !get_raw_handled_net_accesses(dom))
+		return NULL;
+
+	return dom;
+}
+
+static int check_socket_access(struct socket *const sock,
+			       struct sockaddr *const address,
+			       const int addrlen,
+			       const access_mask_t access_request)
+{
+	__be16 port;
+	layer_mask_t layer_masks[LANDLOCK_NUM_ACCESS_NET] = {};
+	const struct landlock_rule *rule;
+	access_mask_t handled_access;
+	struct landlock_id id = {
+		.type = LANDLOCK_KEY_NET_PORT,
+	};
+	const struct landlock_ruleset *const domain = get_current_net_domain();
+
+	if (!domain)
+		return 0;
+	if (WARN_ON_ONCE(domain->num_layers < 1))
+		return -EACCES;
+
+	/* Checks if it's a (potential) TCP socket. */
+	if (sock->type != SOCK_STREAM)
+		return 0;
+
+	/* Checks for minimal header length to safely read sa_family. */
+	if (addrlen < offsetofend(typeof(*address), sa_family))
+		return -EINVAL;
+
+	switch (address->sa_family) {
+	case AF_UNSPEC:
+	case AF_INET:
+		if (addrlen < sizeof(struct sockaddr_in))
+			return -EINVAL;
+		port = ((struct sockaddr_in *)address)->sin_port;
+		break;
+#if IS_ENABLED(CONFIG_IPV6)
+	case AF_INET6:
+		if (addrlen < SIN6_LEN_RFC2133)
+			return -EINVAL;
+		port = ((struct sockaddr_in6 *)address)->sin6_port;
+		break;
+#endif
+	default:
+		return 0;
+	}
+
+	/* Specific AF_UNSPEC handling. */
+	if (address->sa_family == AF_UNSPEC) {
+		/*
+		 * Connecting to an address with AF_UNSPEC dissolves the TCP
+		 * association, which have the same effect as closing the
+		 * connection while retaining the socket object (i.e., the file
+		 * descriptor).  As for dropping privileges, closing
+		 * connections is always allowed.
+		 *
+		 * For a TCP access control system, this request is legitimate.
+		 * Let the network stack handle potential inconsistencies and
+		 * return -EINVAL if needed.
+		 */
+		if (access_request == LANDLOCK_ACCESS_NET_CONNECT_TCP)
+			return 0;
+
+		/*
+		 * For compatibility reason, accept AF_UNSPEC for bind
+		 * accesses (mapped to AF_INET) only if the address is
+		 * INADDR_ANY (cf. __inet_bind).  Checking the address is
+		 * required to not wrongfully return -EACCES instead of
+		 * -EAFNOSUPPORT.
+		 *
+		 * We could return 0 and let the network stack handle these
+		 * checks, but it is safer to return a proper error and test
+		 * consistency thanks to kselftest.
+		 */
+		if (access_request == LANDLOCK_ACCESS_NET_BIND_TCP) {
+			/* addrlen has already been checked for AF_UNSPEC. */
+			const struct sockaddr_in *const sockaddr =
+				(struct sockaddr_in *)address;
+
+			if (sock->sk->__sk_common.skc_family != AF_INET)
+				return -EINVAL;
+
+			if (sockaddr->sin_addr.s_addr != htonl(INADDR_ANY))
+				return -EAFNOSUPPORT;
+		}
+	} else {
+		/*
+		 * Checks sa_family consistency to not wrongfully return
+		 * -EACCES instead of -EINVAL.  Valid sa_family changes are
+		 * only (from AF_INET or AF_INET6) to AF_UNSPEC.
+		 *
+		 * We could return 0 and let the network stack handle this
+		 * check, but it is safer to return a proper error and test
+		 * consistency thanks to kselftest.
+		 */
+		if (address->sa_family != sock->sk->__sk_common.skc_family)
+			return -EINVAL;
+	}
+
+	id.key.data = (__force uintptr_t)port;
+	BUILD_BUG_ON(sizeof(port) > sizeof(id.key.data));
+
+	rule = landlock_find_rule(domain, id);
+	handled_access = landlock_init_layer_masks(
+		domain, access_request, &layer_masks, LANDLOCK_KEY_NET_PORT);
+	if (landlock_unmask_layers(rule, handled_access, &layer_masks,
+				   ARRAY_SIZE(layer_masks)))
+		return 0;
+
+	return -EACCES;
+}
+
+static int hook_socket_bind(struct socket *const sock,
+			    struct sockaddr *const address, const int addrlen)
+{
+	return check_socket_access(sock, address, addrlen,
+				   LANDLOCK_ACCESS_NET_BIND_TCP);
+}
+
+static int hook_socket_connect(struct socket *const sock,
+			       struct sockaddr *const address,
+			       const int addrlen)
+{
+	return check_socket_access(sock, address, addrlen,
+				   LANDLOCK_ACCESS_NET_CONNECT_TCP);
+}
+
+static struct security_hook_list landlock_hooks[] __ro_after_init = {
+	LSM_HOOK_INIT(socket_bind, hook_socket_bind),
+	LSM_HOOK_INIT(socket_connect, hook_socket_connect),
+};
+
+__init void landlock_add_net_hooks(void)
+{
+	security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks),
+			   LANDLOCK_NAME);
+}
diff --git a/security/landlock/net.h b/security/landlock/net.h
new file mode 100644
index 000000000000..0e5016095ff5
--- /dev/null
+++ b/security/landlock/net.h
@@ -0,0 +1,35 @@ 
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Landlock LSM - Network management and hooks
+ *
+ * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
+ */
+
+#ifndef _SECURITY_LANDLOCK_NET_H
+#define _SECURITY_LANDLOCK_NET_H
+
+#include "common.h"
+#include "ruleset.h"
+#include "setup.h"
+
+#if IS_ENABLED(CONFIG_INET)
+__init void landlock_add_net_hooks(void);
+
+int landlock_append_net_rule(struct landlock_ruleset *const ruleset,
+			     const u16 port, access_mask_t access_rights);
+
+int add_rule_net_service(struct landlock_ruleset *ruleset,
+			 const void __user *const rule_attr);
+#else /* IS_ENABLED(CONFIG_INET) */
+static inline void landlock_add_net_hooks(void)
+{
+}
+
+static inline int add_rule_net_service(struct landlock_ruleset *ruleset,
+				       const void __user *const rule_attr)
+{
+	return -EAFNOSUPPORT;
+}
+#endif /* IS_ENABLED(CONFIG_INET) */
+
+#endif /* _SECURITY_LANDLOCK_NET_H */
diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
index 4c209acee01e..1fe4298ff4a7 100644
--- a/security/landlock/ruleset.c
+++ b/security/landlock/ruleset.c
@@ -36,6 +36,11 @@  static struct landlock_ruleset *create_ruleset(const u32 num_layers)
 	refcount_set(&new_ruleset->usage, 1);
 	mutex_init(&new_ruleset->lock);
 	new_ruleset->root_inode = RB_ROOT;
+
+#if IS_ENABLED(CONFIG_INET)
+	new_ruleset->root_net_port = RB_ROOT;
+#endif /* IS_ENABLED(CONFIG_INET) */
+
 	new_ruleset->num_layers = num_layers;
 	/*
 	 * hierarchy = NULL
@@ -46,16 +51,21 @@  static struct landlock_ruleset *create_ruleset(const u32 num_layers)
 }

 struct landlock_ruleset *
-landlock_create_ruleset(const access_mask_t fs_access_mask)
+landlock_create_ruleset(const access_mask_t fs_access_mask,
+			const access_mask_t net_access_mask)
 {
 	struct landlock_ruleset *new_ruleset;

 	/* Informs about useless ruleset. */
-	if (!fs_access_mask)
+	if (!fs_access_mask && !net_access_mask)
 		return ERR_PTR(-ENOMSG);
 	new_ruleset = create_ruleset(1);
-	if (!IS_ERR(new_ruleset))
+	if (IS_ERR(new_ruleset))
+		return new_ruleset;
+	if (fs_access_mask)
 		landlock_add_fs_access_mask(new_ruleset, fs_access_mask, 0);
+	if (net_access_mask)
+		landlock_add_net_access_mask(new_ruleset, net_access_mask, 0);
 	return new_ruleset;
 }

@@ -74,6 +84,11 @@  static bool is_object_pointer(const enum landlock_key_type key_type)
 	case LANDLOCK_KEY_INODE:
 		return true;

+#if IS_ENABLED(CONFIG_INET)
+	case LANDLOCK_KEY_NET_PORT:
+		return false;
+#endif /* IS_ENABLED(CONFIG_INET) */
+
 	default:
 		WARN_ON_ONCE(1);
 		return false;
@@ -126,7 +141,13 @@  static struct rb_root *get_root(struct landlock_ruleset *const ruleset,
 	case LANDLOCK_KEY_INODE:
 		return &ruleset->root_inode;

+#if IS_ENABLED(CONFIG_INET)
+	case LANDLOCK_KEY_NET_PORT:
+		return &ruleset->root_net_port;
+#endif /* IS_ENABLED(CONFIG_INET) */
+
 	default:
+		WARN_ON_ONCE(1);
 		return ERR_PTR(-EINVAL);
 	}
 }
@@ -153,7 +174,8 @@  static void build_check_ruleset(void)
 	BUILD_BUG_ON(ruleset.num_rules < LANDLOCK_MAX_NUM_RULES);
 	BUILD_BUG_ON(ruleset.num_layers < LANDLOCK_MAX_NUM_LAYERS);
 	BUILD_BUG_ON(access_masks <
-		     (LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS));
+		     ((LANDLOCK_MASK_ACCESS_FS << LANDLOCK_SHIFT_ACCESS_FS) |
+		      (LANDLOCK_MASK_ACCESS_NET << LANDLOCK_SHIFT_ACCESS_NET)));
 }

 /**
@@ -370,6 +392,13 @@  static int merge_ruleset(struct landlock_ruleset *const dst,
 	if (err)
 		goto out_unlock;

+#if IS_ENABLED(CONFIG_INET)
+	/* Merges the @src network port tree. */
+	err = merge_tree(dst, src, LANDLOCK_KEY_NET_PORT);
+	if (err)
+		goto out_unlock;
+#endif /* IS_ENABLED(CONFIG_INET) */
+
 out_unlock:
 	mutex_unlock(&src->lock);
 	mutex_unlock(&dst->lock);
@@ -426,6 +455,13 @@  static int inherit_ruleset(struct landlock_ruleset *const parent,
 	if (err)
 		goto out_unlock;

+#if IS_ENABLED(CONFIG_INET)
+	/* Copies the @parent network port tree. */
+	err = inherit_tree(parent, child, LANDLOCK_KEY_NET_PORT);
+	if (err)
+		goto out_unlock;
+#endif /* IS_ENABLED(CONFIG_INET) */
+
 	if (WARN_ON_ONCE(child->num_layers <= parent->num_layers)) {
 		err = -EINVAL;
 		goto out_unlock;
@@ -455,6 +491,13 @@  static void free_ruleset(struct landlock_ruleset *const ruleset)
 	rbtree_postorder_for_each_entry_safe(freeme, next, &ruleset->root_inode,
 					     node)
 		free_rule(freeme, LANDLOCK_KEY_INODE);
+
+#if IS_ENABLED(CONFIG_INET)
+	rbtree_postorder_for_each_entry_safe(freeme, next,
+					     &ruleset->root_net_port, node)
+		free_rule(freeme, LANDLOCK_KEY_NET_PORT);
+#endif /* IS_ENABLED(CONFIG_INET) */
+
 	put_hierarchy(ruleset->hierarchy);
 	kfree(ruleset);
 }
@@ -635,7 +678,8 @@  get_access_mask_t(const struct landlock_ruleset *const ruleset,
  *
  * @domain: The domain that defines the current restrictions.
  * @access_request: The requested access rights to check.
- * @layer_masks: The layer masks to populate.
+ * @layer_masks: It must contain LANDLOCK_NUM_ACCESS_FS or LANDLOCK_NUM_ACCESS_NET
+ * elements according to @key_type.
  * @key_type: The key type to switch between access masks of different types.
  *
  * Returns: An access mask where each access right bit is set which is handled
@@ -656,6 +700,14 @@  landlock_init_layer_masks(const struct landlock_ruleset *const domain,
 		get_access_mask = landlock_get_fs_access_mask;
 		num_access = LANDLOCK_NUM_ACCESS_FS;
 		break;
+
+#if IS_ENABLED(CONFIG_INET)
+	case LANDLOCK_KEY_NET_PORT:
+		get_access_mask = landlock_get_net_access_mask;
+		num_access = LANDLOCK_NUM_ACCESS_NET;
+		break;
+#endif /* IS_ENABLED(CONFIG_INET) */
+
 	default:
 		WARN_ON_ONCE(1);
 		return 0;
diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
index 1ede2b9a79b7..9bd0483c64d4 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -33,13 +33,16 @@ 
 typedef u16 access_mask_t;
 /* Makes sure all filesystem access rights can be stored. */
 static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS);
+/* Makes sure all network access rights can be stored. */
+static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET);
 /* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */
 static_assert(sizeof(unsigned long) >= sizeof(access_mask_t));

 /* Ruleset access masks. */
-typedef u16 access_masks_t;
+typedef u32 access_masks_t;
 /* Makes sure all ruleset access rights can be stored. */
-static_assert(BITS_PER_TYPE(access_masks_t) >= LANDLOCK_NUM_ACCESS_FS);
+static_assert(BITS_PER_TYPE(access_masks_t) >=
+	      LANDLOCK_NUM_ACCESS_FS + LANDLOCK_NUM_ACCESS_NET);

 typedef u16 layer_mask_t;
 /* Makes sure all layers can be checked. */
@@ -84,6 +87,11 @@  enum landlock_key_type {
 	 * keys.
 	 */
 	LANDLOCK_KEY_INODE = 1,
+	/**
+	 * @LANDLOCK_KEY_NET_PORT: Type of &landlock_ruleset.root_net_port's
+	 * node keys.
+	 */
+	LANDLOCK_KEY_NET_PORT = 2,
 };

 /**
@@ -158,6 +166,13 @@  struct landlock_ruleset {
 	 * reaches zero.
 	 */
 	struct rb_root root_inode;
+	/**
+	 * @root_net_port: Root of a red-black tree containing &struct
+	 * landlock_rule nodes with network port. Once a ruleset is tied to a
+	 * process (i.e. as a domain), this tree is immutable until @usage
+	 * reaches zero.
+	 */
+	struct rb_root root_net_port;
 	/**
 	 * @hierarchy: Enables hierarchy identification even when a parent
 	 * domain vanishes.  This is needed for the ptrace protection.
@@ -196,13 +211,13 @@  struct landlock_ruleset {
 			 */
 			u32 num_layers;
 			/**
-			 * @access_masks: Contains the subset of filesystem
-			 * actions that are restricted by a ruleset.  A domain
-			 * saves all layers of merged rulesets in a stack
-			 * (FAM), starting from the first layer to the last
-			 * one.  These layers are used when merging rulesets,
-			 * for user space backward compatibility (i.e.
-			 * future-proof), and to properly handle merged
+			 * @access_masks: Contains the subset of filesystem and
+			 * network actions that are restricted by a ruleset.
+			 * A domain saves all layers of merged rulesets in a
+			 * stack (FAM), starting from the first layer to the
+			 * last one.  These layers are used when merging
+			 * rulesets, for user space backward compatibility
+			 * (i.e. future-proof), and to properly handle merged
 			 * rulesets without overlapping access rights.  These
 			 * layers are set once and never changed for the
 			 * lifetime of the ruleset.
@@ -213,7 +228,8 @@  struct landlock_ruleset {
 };

 struct landlock_ruleset *
-landlock_create_ruleset(const access_mask_t access_mask);
+landlock_create_ruleset(const access_mask_t access_mask_fs,
+			const access_mask_t access_mask_net);

 void landlock_put_ruleset(struct landlock_ruleset *const ruleset);
 void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset);
@@ -249,6 +265,19 @@  landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset,
 		(fs_mask << LANDLOCK_SHIFT_ACCESS_FS);
 }

+static inline void
+landlock_add_net_access_mask(struct landlock_ruleset *const ruleset,
+			     const access_mask_t net_access_mask,
+			     const u16 layer_level)
+{
+	access_mask_t net_mask = net_access_mask & LANDLOCK_MASK_ACCESS_NET;
+
+	/* Should already be checked in sys_landlock_create_ruleset(). */
+	WARN_ON_ONCE(net_access_mask != net_mask);
+	ruleset->access_masks[layer_level] |=
+		(net_mask << LANDLOCK_SHIFT_ACCESS_NET);
+}
+
 static inline access_mask_t
 landlock_get_raw_fs_access_mask(const struct landlock_ruleset *const ruleset,
 				const u16 layer_level)
@@ -266,6 +295,16 @@  landlock_get_fs_access_mask(const struct landlock_ruleset *const ruleset,
 	return landlock_get_raw_fs_access_mask(ruleset, layer_level) |
 	       LANDLOCK_ACCESS_FS_INITIALLY_DENIED;
 }
+
+static inline access_mask_t
+landlock_get_net_access_mask(const struct landlock_ruleset *const ruleset,
+			     const u16 layer_level)
+{
+	return (ruleset->access_masks[layer_level] >>
+		LANDLOCK_SHIFT_ACCESS_NET) &
+	       LANDLOCK_MASK_ACCESS_NET;
+}
+
 bool landlock_unmask_layers(const struct landlock_rule *const rule,
 			    const access_mask_t access_request,
 			    layer_mask_t (*const layer_masks)[],
diff --git a/security/landlock/setup.c b/security/landlock/setup.c
index 0f6113528fa4..df81612811bf 100644
--- a/security/landlock/setup.c
+++ b/security/landlock/setup.c
@@ -14,6 +14,7 @@ 
 #include "fs.h"
 #include "ptrace.h"
 #include "setup.h"
+#include "net.h"

 bool landlock_initialized __ro_after_init = false;

@@ -29,6 +30,7 @@  static int __init landlock_init(void)
 	landlock_add_cred_hooks();
 	landlock_add_ptrace_hooks();
 	landlock_add_fs_hooks();
+	landlock_add_net_hooks();
 	landlock_initialized = true;
 	pr_info("Up and running.\n");
 	return 0;
diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
index 8a54e87dbb17..da6cbd0032ca 100644
--- a/security/landlock/syscalls.c
+++ b/security/landlock/syscalls.c
@@ -29,6 +29,7 @@ 
 #include "cred.h"
 #include "fs.h"
 #include "limits.h"
+#include "net.h"
 #include "ruleset.h"
 #include "setup.h"

@@ -74,7 +75,8 @@  static void build_check_abi(void)
 {
 	struct landlock_ruleset_attr ruleset_attr;
 	struct landlock_path_beneath_attr path_beneath_attr;
-	size_t ruleset_size, path_beneath_size;
+	struct landlock_net_port_attr net_port_attr;
+	size_t ruleset_size, path_beneath_size, net_service_size;

 	/*
 	 * For each user space ABI structures, first checks that there is no
@@ -82,13 +84,19 @@  static void build_check_abi(void)
 	 * struct size.
 	 */
 	ruleset_size = sizeof(ruleset_attr.handled_access_fs);
+	ruleset_size += sizeof(ruleset_attr.handled_access_net);
 	BUILD_BUG_ON(sizeof(ruleset_attr) != ruleset_size);
-	BUILD_BUG_ON(sizeof(ruleset_attr) != 8);
+	BUILD_BUG_ON(sizeof(ruleset_attr) != 16);

 	path_beneath_size = sizeof(path_beneath_attr.allowed_access);
 	path_beneath_size += sizeof(path_beneath_attr.parent_fd);
 	BUILD_BUG_ON(sizeof(path_beneath_attr) != path_beneath_size);
 	BUILD_BUG_ON(sizeof(path_beneath_attr) != 12);
+
+	net_service_size = sizeof(net_port_attr.allowed_access);
+	net_service_size += sizeof(net_port_attr.port);
+	BUILD_BUG_ON(sizeof(net_port_attr) != net_service_size);
+	BUILD_BUG_ON(sizeof(net_port_attr) != 16);
 }

 /* Ruleset handling */
@@ -129,7 +137,7 @@  static const struct file_operations ruleset_fops = {
 	.write = fop_dummy_write,
 };

-#define LANDLOCK_ABI_VERSION 3
+#define LANDLOCK_ABI_VERSION 4

 /**
  * sys_landlock_create_ruleset - Create a new ruleset
@@ -188,8 +196,14 @@  SYSCALL_DEFINE3(landlock_create_ruleset,
 	    LANDLOCK_MASK_ACCESS_FS)
 		return -EINVAL;

+	/* Checks network content (and 32-bits cast). */
+	if ((ruleset_attr.handled_access_net | LANDLOCK_MASK_ACCESS_NET) !=
+	    LANDLOCK_MASK_ACCESS_NET)
+		return -EINVAL;
+
 	/* Checks arguments and transforms to kernel struct. */
-	ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs);
+	ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs,
+					  ruleset_attr.handled_access_net);
 	if (IS_ERR(ruleset))
 		return PTR_ERR(ruleset);

@@ -282,7 +296,7 @@  static int add_rule_path_beneath(struct landlock_ruleset *const ruleset,
 	int res, err;
 	access_mask_t mask;

-	/* Copies raw user space buffer, only one type for now. */
+	/* Copies raw user space buffer. */
 	res = copy_from_user(&path_beneath_attr, rule_attr,
 			     sizeof(path_beneath_attr));
 	if (res)
@@ -320,8 +334,8 @@  static int add_rule_path_beneath(struct landlock_ruleset *const ruleset,
  *
  * @ruleset_fd: File descriptor tied to the ruleset that should be extended
  *		with the new rule.
- * @rule_type: Identify the structure type pointed to by @rule_attr (only
- *             %LANDLOCK_RULE_PATH_BENEATH for now).
+ * @rule_type: Identify the structure type pointed to by @rule_attr:
+ *             %LANDLOCK_RULE_PATH_BENEATH or %LANDLOCK_RULE_NET_PORT.
  * @rule_attr: Pointer to a rule (only of type &struct
  *             landlock_path_beneath_attr for now).
  * @flags: Must be 0.
@@ -332,6 +346,8 @@  static int add_rule_path_beneath(struct landlock_ruleset *const ruleset,
  * Possible returned errors are:
  *
  * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time;
+ * - %EAFNOSUPPORT: @rule_type is LANDLOCK_RULE_NET_PORT but TCP/IP is not
+ *   supported by the running kernel;
  * - %EINVAL: @flags is not 0, or inconsistent access in the rule (i.e.
  *   &landlock_path_beneath_attr.allowed_access is not a subset of the
  *   ruleset handled accesses);
@@ -366,6 +382,9 @@  SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
 	case LANDLOCK_RULE_PATH_BENEATH:
 		err = add_rule_path_beneath(ruleset, rule_attr);
 		break;
+	case LANDLOCK_RULE_NET_PORT:
+		err = add_rule_net_service(ruleset, rule_attr);
+		break;
 	default:
 		err = -EINVAL;
 		break;
diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c
index 792c3f0a59b4..646f778dfb1e 100644
--- a/tools/testing/selftests/landlock/base_test.c
+++ b/tools/testing/selftests/landlock/base_test.c
@@ -75,7 +75,7 @@  TEST(abi_version)
 	const struct landlock_ruleset_attr ruleset_attr = {
 		.handled_access_fs = LANDLOCK_ACCESS_FS_READ_FILE,
 	};
-	ASSERT_EQ(3, landlock_create_ruleset(NULL, 0,
+	ASSERT_EQ(4, landlock_create_ruleset(NULL, 0,
 					     LANDLOCK_CREATE_RULESET_VERSION));

 	ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr, 0,