@@ -17,10 +17,16 @@ MAC extensions, other extensions can be built using the LSM to provide
specific changes to system operation when these tweaks are not available
in the core functionality of Linux itself.
-The Linux capabilities modules will always be included. This may be
-followed by any number of "minor" modules and at most one "major" module.
-For more details on capabilities, see ``capabilities(7)`` in the Linux
-man-pages project.
+The Linux capabilities modules will always be included. For more details
+on capabilities, see ``capabilities(7)`` in the Linux man-pages project.
+
+Security modules that do not use the security data blobs maintained
+by the LSM infrastructure are considered "minor" modules. These may be
+included at compile time and stacked explicitly. Security modules that
+use the LSM maintained security blobs are considered "major" modules.
+These may only be stacked if the CONFIG_LSM_STACKED configuration
+option is used. If this is chosen all of the security modules selected
+will be used.
A list of the active security modules can be found by reading
``/sys/kernel/security/lsm``. This is a comma separated list, and
@@ -2079,7 +2079,7 @@ static inline void security_delete_hooks(struct security_hook_list *hooks,
#define __lsm_ro_after_init __ro_after_init
#endif /* CONFIG_SECURITY_WRITABLE_HOOKS */
-extern int __init security_module_enable(const char *module);
+extern bool __init security_module_enable(const char *lsm, const bool stacked);
extern void __init capability_add_hooks(void);
#ifdef CONFIG_SECURITY_YAMA
extern void __init yama_add_hooks(void);
@@ -36,6 +36,28 @@ config SECURITY_WRITABLE_HOOKS
bool
default n
+config SECURITY_STACKING
+ bool "Security module stacking"
+ depends on SECURITY
+ help
+ Allows multiple major security modules to be stacked.
+ Modules are invoked in the order registered with a
+ "bail on fail" policy, in which the infrastructure
+ will stop processing once a denial is detected. Not
+ all modules can be stacked. SELinux and Smack are
+ known to be incompatible. User space components may
+ have trouble identifying the security module providing
+ data in some cases.
+
+ If you select this option you will have to select which
+ of the stackable modules you wish to be active. The
+ "Default security module" will be ignored. The boot line
+ "security=" option can be used to specify that one of
+ the modules identifed for stacking should be used instead
+ of the entire stack.
+
+ If you are unsure how to answer this question, answer N.
+
config SECURITY_LSM_DEBUG
bool "Enable debugging of the LSM infrastructure"
depends on SECURITY
@@ -251,6 +273,9 @@ source security/yama/Kconfig
source security/integrity/Kconfig
+menu "Security Module Selection"
+ visible if !SECURITY_STACKING
+
choice
prompt "Default security module"
default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
@@ -290,3 +315,64 @@ config DEFAULT_SECURITY
endmenu
+menu "Security Module Stack"
+ visible if SECURITY_STACKING
+
+choice
+ prompt "Stacked 'extreme' security module"
+ default SECURITY_SELINUX_STACKED if SECURITY_SELINUX
+ default SECURITY_SMACK_STACKED if SECURITY_SMACK
+ default SECURITY_APPARMOR_STACKED if SECURITY_APPARMOR
+
+ help
+ Enable an extreme security module. These modules cannot
+ be used at the same time.
+
+ config SECURITY_SELINUX_STACKED
+ bool "SELinux" if SECURITY_SELINUX=y
+ help
+ This option instructs the system to use the SELinux checks.
+ At this time the Smack security module is incompatible with this
+ module.
+ At this time the AppArmor security module is incompatible with this
+ module.
+
+ config SECURITY_SMACK_STACKED
+ bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
+ help
+ This option instructs the system to use the Smack checks.
+ At this time the SELinux security module is incompatible with this
+ module.
+ At this time the AppArmor security module is incompatible with this
+ module.
+
+ config SECURITY_APPARMOR_STACKED
+ bool "AppArmor" if SECURITY_APPARMOR=y
+ help
+ This option instructs the system to use the AppArmor checks.
+ At this time the SELinux security module is incompatible with this
+ module.
+ At this time the Smack security module is incompatible with this
+ module.
+
+ config SECURITY_NOTHING_STACKED
+ bool "Use no 'extreme' security module"
+ help
+ Use none of the SELinux, Smack or AppArmor security module.
+
+endchoice
+
+config SECURITY_TOMOYO_STACKED
+ bool "TOMOYO support is enabled by default"
+ depends on SECURITY_TOMOYO && SECURITY_STACKING
+ default n
+ help
+ This option instructs the system to use the TOMOYO checks.
+ If not selected the module will not be invoked.
+ Stacked security modules may interact in unexpected ways.
+
+ If you are unsure how to answer this question, answer N.
+
+endmenu
+
+endmenu
@@ -25,7 +25,11 @@
static inline struct aa_label *cred_label(const struct cred *cred)
{
+#ifdef CONFIG_SECURITY_STACKING
+ struct aa_label **blob = cred->security + apparmor_blob_sizes.lbs_cred;
+#else
struct aa_label **blob = cred->security;
+#endif
AA_BUG(!blob);
return *blob;
@@ -34,7 +38,11 @@ static inline struct aa_label *cred_label(const struct cred *cred)
static inline void set_cred_label(const struct cred *cred,
struct aa_label *label)
{
+#ifdef CONFIG_SECURITY_STACKING
+ struct aa_label **blob = cred->security + apparmor_blob_sizes.lbs_cred;
+#else
struct aa_label **blob = cred->security;
+#endif
AA_BUG(!blob);
*blob = label;
@@ -32,7 +32,14 @@ struct path;
AA_MAY_CHMOD | AA_MAY_CHOWN | AA_MAY_LOCK | \
AA_EXEC_MMAP | AA_MAY_LINK)
-#define file_ctx(X) ((struct aa_file_ctx *)(X)->f_security)
+static inline struct aa_file_ctx *file_ctx(struct file *file)
+{
+#ifdef CONFIG_SECURITY_STACKING
+ return file->f_security + apparmor_blob_sizes.lbs_file;
+#else
+ return file->f_security;
+#endif
+}
/* struct aa_file_ctx - the AppArmor context the file was opened in
* @lock: lock to update the ctx
@@ -16,6 +16,7 @@
#include <linux/slab.h>
#include <linux/fs.h>
+#include <linux/lsm_hooks.h>
#include "match.h"
@@ -55,6 +56,9 @@ const char *aa_splitn_fqname(const char *fqname, size_t n, const char **ns_name,
size_t *ns_len);
void aa_info_message(const char *str);
+/* Security blob offsets */
+extern struct lsm_blob_sizes apparmor_blob_sizes;
+
/**
* aa_strneq - compare null terminated @str to a non null terminated substring
* @str: a null terminated string
@@ -57,7 +57,11 @@ struct aa_sk_ctx {
static inline struct aa_sk_ctx *aa_sock(const struct sock *sk)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return sk->sk_security + apparmor_blob_sizes.lbs_sock;
+#else
return sk->sk_security;
+#endif
}
#define SOCK_ctx(X) SOCK_INODE(X)->i_security
@@ -16,7 +16,11 @@
static inline struct aa_task_ctx *task_ctx(struct task_struct *task)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return task->security + apparmor_blob_sizes.lbs_task;
+#else
return task->security;
+#endif
}
/*
@@ -1526,7 +1526,9 @@ static int __init apparmor_init(void)
int error;
if (!finish) {
- if (apparmor_enabled && security_module_enable("apparmor"))
+ if (apparmor_enabled &&
+ security_module_enable("apparmor",
+ IS_ENABLED(CONFIG_SECURITY_APPARMOR_STACKED)))
security_add_blobs(&apparmor_blob_sizes);
else
apparmor_enabled = false;
@@ -1534,7 +1536,9 @@ static int __init apparmor_init(void)
return 0;
}
- if (!apparmor_enabled || !security_module_enable("apparmor")) {
+ if (!apparmor_enabled ||
+ !security_module_enable("apparmor",
+ IS_ENABLED(CONFIG_SECURITY_APPARMOR_STACKED))) {
aa_info_message("AppArmor disabled by boot time parameter");
apparmor_enabled = false;
return 0;
@@ -38,6 +38,7 @@
/* Maximum number of letters for an LSM name string */
#define SECURITY_NAME_MAX 10
+#define MODULE_STACK "(stacking)"
struct security_hook_heads security_hook_heads __lsm_ro_after_init;
static ATOMIC_NOTIFIER_HEAD(lsm_notifier_chain);
@@ -50,7 +51,11 @@ static struct lsm_blob_sizes blob_sizes;
/* Boot-time LSM user choice */
static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =
+#ifdef CONFIG_SECURITY_STACKING
+ MODULE_STACK;
+#else
CONFIG_DEFAULT_SECURITY;
+#endif
static void __init do_security_initcalls(void)
{
@@ -174,6 +179,7 @@ static int lsm_append(char *new, char **result)
/**
* security_module_enable - Load given security module on boot ?
* @module: the name of the module
+ * @stacked: indicates that the module wants to be stacked
*
* Each LSM must pass this method before registering its own operations
* to avoid security registration races. This method may also be used
@@ -189,9 +195,29 @@ static int lsm_append(char *new, char **result)
*
* Otherwise, return false.
*/
-int __init security_module_enable(const char *module)
+bool __init security_module_enable(const char *lsm, const bool stacked)
{
- return !strcmp(module, chosen_lsm);
+#ifdef CONFIG_SECURITY_STACKING
+ /*
+ * Module defined on the command line security=XXXX
+ */
+ if (strcmp(chosen_lsm, MODULE_STACK)) {
+ if (!strcmp(lsm, chosen_lsm)) {
+ pr_info("Command line sets the %s security module.\n",
+ lsm);
+ return true;
+ }
+ return false;
+ }
+ /*
+ * Module configured as stacked.
+ */
+ return stacked;
+#else
+ if (strcmp(lsm, chosen_lsm) == 0)
+ return true;
+ return false;
+#endif
}
/**
@@ -6941,7 +6941,8 @@ static __init int selinux_init(void)
{
static int finish;
- if (!security_module_enable("selinux")) {
+ if (!security_module_enable("selinux",
+ IS_ENABLED(CONFIG_SECURITY_SELINUX_STACKED))) {
selinux_enabled = 0;
return 0;
}
@@ -161,48 +161,80 @@ struct bpf_security_struct {
extern struct lsm_blob_sizes selinux_blob_sizes;
static inline struct task_security_struct *selinux_cred(const struct cred *cred)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return cred->security + selinux_blob_sizes.lbs_cred;
+#else
return cred->security;
+#endif
}
static inline struct file_security_struct *selinux_file(const struct file *file)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return file->f_security + selinux_blob_sizes.lbs_file;
+#else
return file->f_security;
+#endif
}
static inline struct inode_security_struct *selinux_inode(
const struct inode *inode)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return inode->i_security + selinux_blob_sizes.lbs_inode;
+#else
return inode->i_security;
+#endif
}
static inline struct superblock_security_struct *selinux_superblock(
const struct super_block *superblock)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return superblock->s_security + selinux_blob_sizes.lbs_superblock;
+#else
return superblock->s_security;
+#endif
}
static inline struct msg_security_struct *selinux_msg_msg(
const struct msg_msg *msg_msg)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return msg_msg->security + selinux_blob_sizes.lbs_msg_msg;
+#else
return msg_msg->security;
+#endif
}
static inline struct ipc_security_struct *selinux_ipc(
const struct kern_ipc_perm *ipc)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return ipc->security + selinux_blob_sizes.lbs_ipc;
+#else
return ipc->security;
+#endif
}
#ifdef CONFIG_KEYS
static inline struct key_security_struct *selinux_key(const struct key *key)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return key->security + selinux_blob_sizes.lbs_key;
+#else
return key->security;
+#endif
}
#endif /* CONFIG_KEYS */
static inline struct sk_security_struct *selinux_sock(const struct sock *sock)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return sock->sk_security + selinux_blob_sizes.lbs_sock;
+#else
return sock->sk_security;
+#endif
}
#endif /* _SELINUX_OBJSEC_H_ */
@@ -337,6 +337,7 @@ extern struct smack_known *smack_syslog_label;
extern struct smack_known *smack_unconfined;
#endif
extern int smack_ptrace_rule;
+extern struct lsm_blob_sizes smack_blob_sizes;
extern struct smack_known smack_known_floor;
extern struct smack_known smack_known_hat;
@@ -359,44 +360,76 @@ extern struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];
static inline struct task_smack *smack_cred(const struct cred *cred)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return cred->security + smack_blob_sizes.lbs_cred;
+#else
return cred->security;
+#endif
}
static inline struct smack_known **smack_file(const struct file *file)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return file->f_security + smack_blob_sizes.lbs_file;
+#else
return file->f_security;
+#endif
}
static inline struct inode_smack *smack_inode(const struct inode *inode)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return inode->i_security + smack_blob_sizes.lbs_inode;
+#else
return inode->i_security;
+#endif
}
static inline struct socket_smack *smack_sock(const struct sock *sock)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return sock->sk_security + smack_blob_sizes.lbs_sock;
+#else
return sock->sk_security;
+#endif
}
static inline struct superblock_smack *smack_superblock(
const struct super_block *superblock)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return superblock->s_security + smack_blob_sizes.lbs_superblock;
+#else
return superblock->s_security;
+#endif
}
static inline struct smack_known **smack_msg_msg(const struct msg_msg *msg)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return msg->security + smack_blob_sizes.lbs_msg_msg;
+#else
return msg->security;
+#endif
}
static inline struct smack_known **smack_ipc(const struct kern_ipc_perm *ipc)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return ipc->security + smack_blob_sizes.lbs_ipc;
+#else
return ipc->security;
+#endif
}
#ifdef CONFIG_KEYS
static inline struct smack_known **smack_key(const struct key *key)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return key->security + smack_blob_sizes.lbs_key;
+#else
return key->security;
+#endif
}
#endif /* CONFIG_KEYS */
@@ -3449,18 +3449,16 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value)
{
struct smack_known *skp = smk_of_task_struct(p);
char *cp;
- int slen;
- if (strcmp(name, "current") != 0)
+ if (strcmp(name, "current") == 0) {
+ cp = kstrdup(skp->smk_known, GFP_KERNEL);
+ if (cp == NULL)
+ return -ENOMEM;
+ } else
return -EINVAL;
- cp = kstrdup(skp->smk_known, GFP_KERNEL);
- if (cp == NULL)
- return -ENOMEM;
-
- slen = strlen(cp);
*value = cp;
- return slen;
+ return strlen(cp);
}
/**
@@ -4699,7 +4697,8 @@ static __init int smack_init(void)
struct cred *cred = (struct cred *) current->cred;
struct task_smack *tsp;
- if (!security_module_enable("smack"))
+ if (!security_module_enable("smack",
+ IS_ENABLED(CONFIG_SECURITY_SMACK_STACKED)))
return 0;
if (!finish) {
@@ -1087,6 +1087,7 @@ extern struct tomoyo_domain_info tomoyo_kernel_domain;
extern struct tomoyo_policy_namespace tomoyo_kernel_namespace;
extern unsigned int tomoyo_memory_quota[TOMOYO_MAX_MEMORY_STAT];
extern unsigned int tomoyo_memory_used[TOMOYO_MAX_MEMORY_STAT];
+extern struct lsm_blob_sizes tomoyo_blob_sizes;
/********** Inlined functions. **********/
@@ -1206,7 +1207,11 @@ static inline void tomoyo_put_group(struct tomoyo_group *group)
*/
static inline struct tomoyo_domain_info **tomoyo_cred(const struct cred *cred)
{
+#ifdef CONFIG_SECURITY_STACKING
+ return cred->security + tomoyo_blob_sizes.lbs_cred;
+#else
return cred->security;
+#endif
}
/**
@@ -1216,8 +1221,13 @@ static inline struct tomoyo_domain_info **tomoyo_cred(const struct cred *cred)
*/
static inline struct tomoyo_domain_info *tomoyo_domain(void)
{
- struct tomoyo_domain_info **blob = tomoyo_cred(current_cred());
+ const struct cred *cred = current_cred();
+ struct tomoyo_domain_info **blob;
+
+ if (cred->security == NULL)
+ return NULL;
+ blob = tomoyo_cred(cred);
return *blob;
}
@@ -564,7 +564,8 @@ static int __init tomoyo_init(void)
struct cred *cred = (struct cred *) current_cred();
struct tomoyo_domain_info **blob;
- if (!security_module_enable("tomoyo")) {
+ if (!security_module_enable("tomoyo",
+ IS_ENABLED(CONFIG_SECURITY_TOMOYO_STACKED))) {
tomoyo_enabled = false;
return 0;
}
[PATCH 16/22] LSM: Sharing of security blobs Augment the security modules that use security blobs ("Major" security modules) to allow sharing of the infrastructure allocated blobs. When CONFIG_SECURITY_STACKING is specified the blob pointer abstraction functions introduced earlier use the offset information provided by the infrastructure to find the data in the blob that is for use by the acting security module. The mechanism for specifying the active security modules has been changed. SELinux, Smack and AppArmor have behaviors beyond the sharing of security blobs that prevent them from working together at this point. TOMOYO does not have this limitation. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> --- Documentation/admin-guide/LSM/index.rst | 14 ++-- include/linux/lsm_hooks.h | 2 +- security/Kconfig | 86 +++++++++++++++++++++++++ security/apparmor/include/cred.h | 8 +++ security/apparmor/include/file.h | 9 ++- security/apparmor/include/lib.h | 4 ++ security/apparmor/include/net.h | 4 ++ security/apparmor/include/task.h | 4 ++ security/apparmor/lsm.c | 8 ++- security/security.c | 30 ++++++++- security/selinux/hooks.c | 3 +- security/selinux/include/objsec.h | 32 +++++++++ security/smack/smack.h | 33 ++++++++++ security/smack/smack_lsm.c | 17 +++-- security/tomoyo/common.h | 12 +++- security/tomoyo/tomoyo.c | 3 +- 16 files changed, 247 insertions(+), 22 deletions(-)