[v17,00/10] Landlock LSM

Message

Mickaël Salaün May 11, 2020, 7:21 p.m. UTC

Hi,

This new patch series brings some improvements and add new tests:

Use smaller userspace structures (attributes) to save space, and check
at built time that every attribute don't contain hole and are 8-bits
aligned.

Allow enforcement of empty ruleset, which enables deny-all policies
(useful for strict sandboxes).

I found that UML may not keep the same internal struct inode for an open
file.  Because the Landlock filesystem access-control relies on internal
kernel states, special architectures such as UML can't support Landlock.
Add a new ARCH_EPHEMERAL_STATES to identify such architectures.

Add a size_attr_features field to struct landlock_attr_features for
self-introspection

Switch syscall attribute pointer and size arguments to follow similar
syscalls argument order (e.g. bpf, clone3, openat2).


The SLOC count is 1288 for security/landlock/ and 1740 for
tools/testing/selftest/landlock/ .  Test coverage for security/landlock/
is 93.6% of lines.  The code not covered only deals with internal kernel
errors (e.g. memory allocation) and race conditions.

The compiled documentation is available here:
https://landlock.io/linux-doc/landlock-v17/security/landlock/index.html

This series can be applied on top of v5.7-rc5.  This can be tested with
CONFIG_SECURITY_LANDLOCK and CONFIG_SAMPLE_LANDLOCK.  This patch series
can be found in a Git repository here:
https://github.com/landlock-lsm/linux/commits/landlock-v17
I would really appreciate constructive comments on this patch series.


# Landlock LSM

The goal of Landlock is to enable to restrict ambient rights (e.g.
global filesystem access) for a set of processes.  Because Landlock is a
stackable LSM [2], it makes possible to create safe security sandboxes
as new security layers in addition to the existing system-wide
access-controls. This kind of sandbox is expected to help mitigate the
security impact of bugs or unexpected/malicious behaviors in user-space
applications. Landlock empowers any process, including unprivileged
ones, to securely restrict themselves.

Landlock is inspired by seccomp-bpf but instead of filtering syscalls
and their raw arguments, a Landlock rule can restrict the use of kernel
objects like file hierarchies, according to the kernel semantic.
Landlock also takes inspiration from other OS sandbox mechanisms: XNU
Sandbox, FreeBSD Capsicum or OpenBSD Pledge/Unveil.


Previous version:
https://lore.kernel.org/lkml/[e-mail]/


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

Regards,

Mickaël Salaün (10):
  landlock: Add object management
  landlock: Add ruleset and domain management
  landlock: Set up the security framework and manage credentials
  landlock: Add ptrace restrictions
  fs,landlock: Support filesystem access-control
  landlock: Add syscall implementation
  arch: Wire up landlock() syscall
  selftests/landlock: Add initial tests
  samples/landlock: Add a sandbox manager example
  landlock: Add user and kernel documentation

 Documentation/security/index.rst              |    1 +
 Documentation/security/landlock/index.rst     |   18 +
 Documentation/security/landlock/kernel.rst    |   69 +
 Documentation/security/landlock/user.rst      |  268 +++
 MAINTAINERS                                   |   12 +
 arch/Kconfig                                  |    7 +
 arch/alpha/kernel/syscalls/syscall.tbl        |    1 +
 arch/arm/tools/syscall.tbl                    |    1 +
 arch/arm64/include/asm/unistd.h               |    2 +-
 arch/arm64/include/asm/unistd32.h             |    2 +
 arch/ia64/kernel/syscalls/syscall.tbl         |    1 +
 arch/m68k/kernel/syscalls/syscall.tbl         |    1 +
 arch/microblaze/kernel/syscalls/syscall.tbl   |    1 +
 arch/mips/kernel/syscalls/syscall_n32.tbl     |    1 +
 arch/mips/kernel/syscalls/syscall_n64.tbl     |    1 +
 arch/mips/kernel/syscalls/syscall_o32.tbl     |    1 +
 arch/parisc/kernel/syscalls/syscall.tbl       |    1 +
 arch/powerpc/kernel/syscalls/syscall.tbl      |    1 +
 arch/s390/kernel/syscalls/syscall.tbl         |    1 +
 arch/sh/kernel/syscalls/syscall.tbl           |    1 +
 arch/sparc/kernel/syscalls/syscall.tbl        |    1 +
 arch/um/Kconfig                               |    1 +
 arch/x86/entry/syscalls/syscall_32.tbl        |    1 +
 arch/x86/entry/syscalls/syscall_64.tbl        |    1 +
 arch/xtensa/kernel/syscalls/syscall.tbl       |    1 +
 fs/super.c                                    |    2 +
 include/linux/fs.h                            |    5 +
 include/linux/landlock.h                      |   22 +
 include/linux/syscalls.h                      |    3 +
 include/uapi/asm-generic/unistd.h             |    4 +-
 include/uapi/linux/landlock.h                 |  302 +++
 kernel/sys_ni.c                               |    3 +
 samples/Kconfig                               |    7 +
 samples/Makefile                              |    1 +
 samples/landlock/.gitignore                   |    1 +
 samples/landlock/Makefile                     |   15 +
 samples/landlock/sandboxer.c                  |  228 +++
 security/Kconfig                              |   11 +-
 security/Makefile                             |    2 +
 security/landlock/Kconfig                     |   18 +
 security/landlock/Makefile                    |    4 +
 security/landlock/common.h                    |   20 +
 security/landlock/cred.c                      |   46 +
 security/landlock/cred.h                      |   58 +
 security/landlock/fs.c                        |  601 ++++++
 security/landlock/fs.h                        |   42 +
 security/landlock/object.c                    |   66 +
 security/landlock/object.h                    |   91 +
 security/landlock/ptrace.c                    |  120 ++
 security/landlock/ptrace.h                    |   14 +
 security/landlock/ruleset.c                   |  342 ++++
 security/landlock/ruleset.h                   |  161 ++
 security/landlock/setup.c                     |   39 +
 security/landlock/setup.h                     |   18 +
 security/landlock/syscall.c                   |  532 +++++
 tools/testing/selftests/Makefile              |    1 +
 tools/testing/selftests/landlock/.gitignore   |    2 +
 tools/testing/selftests/landlock/Makefile     |   29 +
 tools/testing/selftests/landlock/base_test.c  |  170 ++
 tools/testing/selftests/landlock/common.h     |  108 +
 tools/testing/selftests/landlock/config       |    5 +
 tools/testing/selftests/landlock/fs_test.c    | 1729 +++++++++++++++++
 .../testing/selftests/landlock/ptrace_test.c  |  293 +++
 tools/testing/selftests/landlock/true.c       |    5 +
 64 files changed, 5509 insertions(+), 7 deletions(-)
 create mode 100644 Documentation/security/landlock/index.rst
 create mode 100644 Documentation/security/landlock/kernel.rst
 create mode 100644 Documentation/security/landlock/user.rst
 create mode 100644 include/linux/landlock.h
 create mode 100644 include/uapi/linux/landlock.h
 create mode 100644 samples/landlock/.gitignore
 create mode 100644 samples/landlock/Makefile
 create mode 100644 samples/landlock/sandboxer.c
 create mode 100644 security/landlock/Kconfig
 create mode 100644 security/landlock/Makefile
 create mode 100644 security/landlock/common.h
 create mode 100644 security/landlock/cred.c
 create mode 100644 security/landlock/cred.h
 create mode 100644 security/landlock/fs.c
 create mode 100644 security/landlock/fs.h
 create mode 100644 security/landlock/object.c
 create mode 100644 security/landlock/object.h
 create mode 100644 security/landlock/ptrace.c
 create mode 100644 security/landlock/ptrace.h
 create mode 100644 security/landlock/ruleset.c
 create mode 100644 security/landlock/ruleset.h
 create mode 100644 security/landlock/setup.c
 create mode 100644 security/landlock/setup.h
 create mode 100644 security/landlock/syscall.c
 create mode 100644 tools/testing/selftests/landlock/.gitignore
 create mode 100644 tools/testing/selftests/landlock/Makefile
 create mode 100644 tools/testing/selftests/landlock/base_test.c
 create mode 100644 tools/testing/selftests/landlock/common.h
 create mode 100644 tools/testing/selftests/landlock/config
 create mode 100644 tools/testing/selftests/landlock/fs_test.c
 create mode 100644 tools/testing/selftests/landlock/ptrace_test.c
 create mode 100644 tools/testing/selftests/landlock/true.c

Comments

Mickaël Salaün May 11, 2020, 9:54 p.m. UTC | #1

On 11/05/2020 21:21, Mickaël Salaün wrote:
> Hi,
> 
> This new patch series brings some improvements and add new tests:
> 
> Use smaller userspace structures (attributes) to save space, and check
> at built time that every attribute don't contain hole and are 8-bits
> aligned.

8-bytes aligned, of course.