commit | f65da3a91d350345a3b2a4e365314c5efdb13851 | [log] [tgz] |
---|---|---|
author | Stéphane Lesimple <[email protected]> | Tue Jan 11 11:44:47 2022 +0100 |
committer | Stéphane Lesimple <[email protected]> | Wed Jan 26 12:24:58 2022 +0100 |
tree | 8edf419ba5f5e2b590ad3bf6a40fb8388f0af27c | |
parent | e16ab3ed5f0882b583185b9a07fc4e4bbc11d470 [diff] |
minijail0: implement --env-reset and --env-add The default behavior of minijail0 is to transmit its own environment to the program it launches. These two options enable modification of this standard behavior, by setting up a specific environment for the target program. * --env-reset prevents minijail0 to pass its own environment to the program. Note that if this option is used without any --env-add option, the program starts with a completely empty environment. * --env-add allows setting any number of environment variables to be added to the environment set up for the program. Note that the special environment variable LD_PRELOAD can also be set this way, without impacting minijail0's own invocation. Test: `make tests` Test: `valgrind ./minijail0 --env-add A=X /usr/bin/env` Test: `valgrind ./minijail0 --env-add A=X --env-add A=Y /usr/bin/env` Test: `valgrind ./minijail0 --env-reset /usr/bin/env` Test: `valgrind ./minijail0 --env-reset --env-reset /usr/bin/env` Test: `valgrind ./minijail0 --env-reset --env-add A=X /usr/bin/env` Test: `valgrind ./minijail0 --env-add A=X --env-reset --env-add A=Y /usr/bin/env` Test: `valgrind ./minijail0 --env-add A=X --env-reset --env-add A=Y --env-reset /usr/bin/env` Test: `minijail0 --env-reset --env-add LD_PRELOAD="a b" --env-add FOO=bar /usr/bin/env` """ ERROR: ld.so: object 'a' from LD_PRELOAD cannot be preloaded (cannot open shared object file): ignored. ERROR: ld.so: object 'b' from LD_PRELOAD cannot be preloaded (cannot open shared object file): ignored. LD_PRELOAD=a b FOO=bar """ Change-Id: I2e106003824ff6707b80b6653141657e4ec40f47
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!
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.
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
See the HACKING.md document for more details.
See the RELEASE.md document for more details.
See the tools/README.md document for more details.
We've got a couple of contact points.
The following talk serves as a good introduction to Minijail and how it can be used.
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.
# 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)
# minijail0 -u jorgelo -c 3000 -- /bin/cat /proc/self/status Name: cat ... CapInh: 0000000000003000 CapPrm: 0000000000003000 CapEff: 0000000000003000 CapBnd: 0000000000003000
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@.
Minijail is manually upgraded on Chrome OS so that there is a way to test changes in the Chrome OS commit queue. Committed changes have already passed Android's presubmit checks, but the ebuild upgrade CL goes through the Chrome OS commit queue and must pass the tests before any additional changes are available for use on Chrome OS. To upgrade minijail on Chrome OS, complete the following steps.
# Sync Minijail repo cd ~/chromiumos/src/aosp/external/minijail git checkout m/main repo sync . # Set up local branch. cd ~/trunk/src/third_party/chromiumos-overlay/ repo start minijail . # replace minijail with the local branch name you want. # Run upgrade script. ~/trunk/chromite/scripts/cros_uprev --force --overlay-type public \ --packages chromeos-base/minijail:dev-rust/minijail-sys:dev-rust/minijail
At this point the Minijail-related packages should be upgraded, so you may want to add the changes to a commit and do some local testing before uploading a change list. Here are the recommended local tests to try (make sure you are not working on the minijail packages first i.e. cros_workon list-all
):
# Check build. ./build_packages --board=${BOARD} # Check unit tests. FEATURES=test emerge-${BOARD} chromeos-base/minijail dev-rust/minijail-sys \ dev-rust/minijail # Check integration tests. cros deploy <DUT> chromeos-base/minijail tast run <DUT> security.Minijail security.MinijailSeccomp
Finally, when uploading the CL make sure to include the list of changes since the last uprev. The command to generate the list is as follows:
git log --oneline --no-merges <previous hash in ebuild file>..HEAD