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android / platform / external / minijail / 9e1ac371045d0c2b4200441ccaa35188fa088988
commit9e1ac371045d0c2b4200441ccaa35188fa088988[log] [tgz]
authorJorge Lucangeli Obes <[email protected]>Thu Jan 23 14:36:50 2020 -0500
committerTreehugger Robot <[email protected]>Wed Sep 09 17:05:50 2020 +0000
tree030733f1e081dbcd16dd742f667d8b0a47334444
parent4fc5781ed3ee9430291f5281812f4f6655eb70df [diff]
minijail0: Remount mounts as MS_SLAVE by default.

When executing the sandboxed program in a new mount namespace the
Minijail library will by default remount all mounts with the MS_PRIVATE
flag. While this is an appropriate, safe default for the library,
MS_PRIVATE can be problematic: unmount events will not propagate into
mountpoints marked as MS_PRIVATE. This can cause bugs (see code
comments for details.)

Fix by keeping MS_PRIVATE as default in libminijail.c but switch the
default in minijail0_cli.c to MS_SLAVE.

In order to avoid command-lines like "-Kprivate -v" overriding the -K
option, call set_remount_mode() after all command-line options have
been processed.

Bug: 147609789
Test: Unit tests pass.
Test: See repro steps in bug.
Test: "minijail0 -Kprivate -v" remounts with MS_PRIVATE.

Change-Id: I4788ffb92309d9b6e02a38ef2998bcecf5314b50
3 files changed
tree: 030733f1e081dbcd16dd742f667d8b0a47334444
  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. OWNERS.rust
  50. parse_seccomp_policy.cc
  51. platform2_preinstall.sh
  52. PRESUBMIT.cfg
  53. PREUPLOAD.cfg
  54. README.md
  55. RELEASE.md
  56. scoped_minijail.h
  57. setup.py
  58. signal_handler.c
  59. signal_handler.h
  60. syscall_filter.c
  61. syscall_filter.h
  62. syscall_filter_unittest.cc
  63. syscall_filter_unittest_macros.h
  64. syscall_wrapper.c
  65. syscall_wrapper.h
  66. system.c
  67. system.h
  68. system_unittest.cc
  69. TEST_MAPPING
  70. testrunner.cc
  71. util.c
  72. util.h
  73. util_unittest.cc
README.md

Minijail

The Minijail homepage and main 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