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android / platform / external / minijail / ceb800091b03171c3998a57e37c25ac523c23b4d
commitceb800091b03171c3998a57e37c25ac523c23b4d[log] [tgz]
authorNicole Anderson-Au <[email protected]>Thu May 27 21:43:46 2021 +0000
committerNicole Anderson-Au <[email protected]>Tue Jun 01 16:58:19 2021 +0000
tree2705bbcf7bc0450aa618886ddacfbd70bd0c4b0f
parent2453b1fc097f3a995be8bcc0a2ada1fba616f287 [diff]
minijail: Modify compile_seccomp_policy to compile denylist policies

Add an option to compile_seccomp_policy.py to be able to compile
denylist policies.

BUG=chromium:1162104
TEST=$ ../tools/compile_seccomp_policy.py --denylist
        \ generated_policy.policy simple_filter
$ libseccomp/tools/scmp_bpf_disasm < simple_filter
Check that bpf is for a denylist policy

Change-Id: I98b945bb8f77a15afb5e5805ecbcc5a135dd8d12
2 files changed
tree: 2705bbcf7bc0450aa618886ddacfbd70bd0c4b0f
  1. .github/
  2. examples/
  3. linux-x86/
  4. rust/
  5. test/
  6. tools/
  7. .clang-format
  8. .gitignore
  9. Android.bp
  10. arch.h
  11. bpf.c
  12. bpf.h
  13. CleanSpec.mk
  14. common.mk
  15. CPPLINT.cfg
  16. dump_constants.cc
  17. elfparse.c
  18. elfparse.h
  19. gen_constants-inl.h
  20. gen_constants.c
  21. gen_constants.sh
  22. gen_syscalls-inl.h
  23. gen_syscalls.c
  24. gen_syscalls.sh
  25. get_googletest.sh
  26. HACKING.md
  27. libconstants.h
  28. libminijail-private.h
  29. libminijail.c
  30. libminijail.h
  31. libminijail.pc.in
  32. libminijail_unittest.cc
  33. libminijailpreload.c
  34. libsyscalls.h
  35. LICENSE
  36. Makefile
  37. METADATA
  38. minijail0.1
  39. minijail0.5
  40. minijail0.c
  41. minijail0.sh
  42. minijail0_cli.c
  43. minijail0_cli.h
  44. minijail0_cli_unittest.cc
  45. MODULE_LICENSE_BSD
  46. navbar.md
  47. NOTICE
  48. OWNERS
  49. parse_seccomp_policy.cc
  50. platform2_preinstall.sh
  51. PRESUBMIT.cfg
  52. PREUPLOAD.cfg
  53. README.md
  54. RELEASE.md
  55. scoped_minijail.h
  56. setup.py
  57. signal_handler.c
  58. signal_handler.h
  59. syscall_filter.c
  60. syscall_filter.h
  61. syscall_filter_unittest.cc
  62. syscall_filter_unittest_macros.h
  63. syscall_wrapper.c
  64. syscall_wrapper.h
  65. system.c
  66. system.h
  67. system_unittest.cc
  68. TEST_MAPPING
  69. testrunner.cc
  70. util.c
  71. util.h
  72. util_unittest.cc
README.md

Minijail

The Minijail homepage is https://google.github.io/minijail/.

The main source repo is https://android.googlesource.com/platform/external/minijail/.

There might be other copies floating around, but this is the official one!

What is it?

Minijail is a sandboxing and containment tool used in Chrome OS and Android. It provides an executable that can be used to launch and sandbox other programs, and a library that can be used by code to sandbox itself.

Getting the code

You're one git clone away from happiness.

$ git clone https://android.googlesource.com/platform/external/minijail
$ cd minijail

Releases are tagged as linux-vXX: https://android.googlesource.com/platform/external/minijail/+refs

Building

See the HACKING.md document for more details.

Release process

See the RELEASE.md document for more details.

Additional tools

See the tools/README.md document for more details.

Contact

We've got a couple of contact points.

Talks and presentations

The following talk serves as a good introduction to Minijail and how it can be used.

Video, slides.

Example usage

The Chromium OS project has a comprehensive sandboxing document that is largely based on Minijail.

After you play with the simple examples below, you should check that out.

Change root to any user

# id
uid=0(root) gid=0(root) groups=0(root),128(pkcs11)
# minijail0 -u jorgelo -g 5000 /usr/bin/id
uid=72178(jorgelo) gid=5000(eng) groups=5000(eng)

Drop root while keeping some capabilities

# minijail0 -u jorgelo -c 3000 -- /bin/cat /proc/self/status
Name: cat
...
CapInh: 0000000000003000
CapPrm: 0000000000003000
CapEff: 0000000000003000
CapBnd: 0000000000003000

Historical notes

Q. “Why is it called minijail0?”

A. It is minijail0 because it was a rewrite of an earlier program named minijail, which was considerably less mini, and in particular had a dependency on libchrome (the Chrome OS packaged version of Chromium's //base). We needed a new name to not collide with the deprecated one.

We didn‘t want to call it minijail2 or something that would make people start using it before we were ready, and it was also concretely less since it dropped libbase, etc. Technically, we needed to be able to fork/preload with minimal extra syscall noise which was too hard with libbase at the time (onexit handlers, etc that called syscalls we didn’t want to allow). Also, Elly made a strong case that C would be the right choice for this for linking and ease of controlled surprise system call use.

https://crrev.com/c/4585/ added the original implementation.

Source: Conversations with original authors, ellyjones@ and wad@.