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android / platform / external / minijail / b06ce9b6f7303c4fca92e9eea08588c967cad9e0
commitb06ce9b6f7303c4fca92e9eea08588c967cad9e0[log] [tgz]
authorRichard Fung <[email protected]>Tue May 11 20:11:57 2021 +0000
committerRichard Fung <[email protected]>Tue May 18 16:53:02 2021 +0000
treee10726754d6af91d3badecf7c0994c84cd7f3e27
parent14ad2ce8a6e3f952d8ce4ca364c26fb1cdbc3454 [diff]
Increase MAX_PRESERVED_FDS to 128

This increases the max number of file descriptors of crosvm allowed. The
--composite-disk feature uses a file descriptor for each bundled disk
which made it easy to hit the previous limit.

Bug: b/187841426
Test: crosvm starts with patch

Change-Id: I6056f16cd4893a5a7580e05013e38907c0ef17e4
1 file changed
tree: e10726754d6af91d3badecf7c0994c84cd7f3e27
  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@.