[v25,00/12] Landlock LSM

Message

Mickaël Salaün Dec. 1, 2020, 7:23 p.m. UTC

Hi,

This patch series mainly extend Landlock rules to store the whole access
rights stack.  This enables to tie access rights with their respective
layers to be able to have a sane semantic regardless of the previous
enforced rulesets.  This also enables to get back the union of access
rights when building a ruleset.  See layout1.interleaved_masked_accesses
tests from tools/testing/selftests/landlock/fs_test.c for corner cases.
Cf.
https://lore.kernel.org/lkml/[e-mail]/

The SLOC count is 1260 for security/landlock/ and 1711 for
tools/testing/selftest/landlock/ .  Test coverage for security/landlock/
is 94% 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-v25/userspace-api/landlock.html

This series can be applied on top of v5.10-rc6 .  This can be tested
with CONFIG_SECURITY_LANDLOCK, CONFIG_SAMPLE_LANDLOCK and by prepending
"landlock," to CONFIG_LSM.  This patch series can be found in a Git
repository here:
https://github.com/landlock-lsm/linux/commits/landlock-v25
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 [1], 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.

In this current form, Landlock misses some access-control features.
This enables to minimize this patch series and ease review.  This series
still addresses multiple use cases, especially with the combined use of
seccomp-bpf: applications with built-in sandboxing, init systems,
security sandbox tools and security-oriented APIs [2].

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]/


Casey Schaufler (1):
  LSM: Infrastructure management of the superblock

Mickaël Salaün (11):
  landlock: Add object management
  landlock: Add ruleset and domain management
  landlock: Set up the security framework and manage credentials
  landlock: Add ptrace restrictions
  fs,security: Add sb_delete hook
  landlock: Support filesystem access-control
  landlock: Add syscall implementations
  arch: Wire up Landlock syscalls
  selftests/landlock: Add user space tests
  samples/landlock: Add a sandbox manager example
  landlock: Add user and kernel documentation

 Documentation/security/index.rst              |    1 +
 Documentation/security/landlock.rst           |   79 +
 Documentation/userspace-api/index.rst         |    1 +
 Documentation/userspace-api/landlock.rst      |  280 +++
 MAINTAINERS                                   |   13 +
 arch/Kconfig                                  |    7 +
 arch/alpha/kernel/syscalls/syscall.tbl        |    3 +
 arch/arm/tools/syscall.tbl                    |    3 +
 arch/arm64/include/asm/unistd.h               |    2 +-
 arch/arm64/include/asm/unistd32.h             |    6 +
 arch/ia64/kernel/syscalls/syscall.tbl         |    3 +
 arch/m68k/kernel/syscalls/syscall.tbl         |    3 +
 arch/microblaze/kernel/syscalls/syscall.tbl   |    3 +
 arch/mips/kernel/syscalls/syscall_n32.tbl     |    3 +
 arch/mips/kernel/syscalls/syscall_n64.tbl     |    3 +
 arch/mips/kernel/syscalls/syscall_o32.tbl     |    3 +
 arch/parisc/kernel/syscalls/syscall.tbl       |    3 +
 arch/powerpc/kernel/syscalls/syscall.tbl      |    3 +
 arch/s390/kernel/syscalls/syscall.tbl         |    3 +
 arch/sh/kernel/syscalls/syscall.tbl           |    3 +
 arch/sparc/kernel/syscalls/syscall.tbl        |    3 +
 arch/um/Kconfig                               |    1 +
 arch/x86/entry/syscalls/syscall_32.tbl        |    3 +
 arch/x86/entry/syscalls/syscall_64.tbl        |    3 +
 arch/xtensa/kernel/syscalls/syscall.tbl       |    3 +
 fs/super.c                                    |    1 +
 include/linux/lsm_hook_defs.h                 |    1 +
 include/linux/lsm_hooks.h                     |    3 +
 include/linux/security.h                      |    4 +
 include/linux/syscalls.h                      |    7 +
 include/uapi/asm-generic/unistd.h             |    8 +-
 include/uapi/linux/landlock.h                 |  128 ++
 kernel/sys_ni.c                               |    5 +
 samples/Kconfig                               |    7 +
 samples/Makefile                              |    1 +
 samples/landlock/.gitignore                   |    1 +
 samples/landlock/Makefile                     |   15 +
 samples/landlock/sandboxer.c                  |  236 +++
 security/Kconfig                              |   11 +-
 security/Makefile                             |    2 +
 security/landlock/Kconfig                     |   21 +
 security/landlock/Makefile                    |    4 +
 security/landlock/common.h                    |   20 +
 security/landlock/cred.c                      |   46 +
 security/landlock/cred.h                      |   58 +
 security/landlock/fs.c                        |  635 ++++++
 security/landlock/fs.h                        |   60 +
 security/landlock/object.c                    |   67 +
 security/landlock/object.h                    |   91 +
 security/landlock/ptrace.c                    |  120 ++
 security/landlock/ptrace.h                    |   14 +
 security/landlock/ruleset.c                   |  427 ++++
 security/landlock/ruleset.h                   |  163 ++
 security/landlock/setup.c                     |   40 +
 security/landlock/setup.h                     |   18 +
 security/landlock/syscall.c                   |  426 ++++
 security/security.c                           |   51 +-
 security/selinux/hooks.c                      |   58 +-
 security/selinux/include/objsec.h             |    6 +
 security/selinux/ss/services.c                |    3 +-
 security/smack/smack.h                        |    6 +
 security/smack/smack_lsm.c                    |   35 +-
 tools/testing/selftests/Makefile              |    1 +
 tools/testing/selftests/landlock/.gitignore   |    2 +
 tools/testing/selftests/landlock/Makefile     |   24 +
 tools/testing/selftests/landlock/base_test.c  |  117 ++
 tools/testing/selftests/landlock/common.h     |  113 ++
 tools/testing/selftests/landlock/config       |    5 +
 tools/testing/selftests/landlock/fs_test.c    | 1798 +++++++++++++++++
 .../testing/selftests/landlock/ptrace_test.c  |  307 +++
 tools/testing/selftests/landlock/true.c       |    5 +
 71 files changed, 5532 insertions(+), 77 deletions(-)
 create mode 100644 Documentation/security/landlock.rst
 create mode 100644 Documentation/userspace-api/landlock.rst
 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


base-commit: b65054597872ce3aefbc6a666385eabdf9e288da