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| author | Nick Pelly <npelly@google.com> | 2010-01-21 18:13:39 -0800 |
|---|---|---|
| committer | Nick Pelly <npelly@google.com> | 2010-01-22 11:50:49 -0800 |
| commit | 6405c6953fa02d41d9f6377f4cdb947604f481c4 (patch) | |
| tree | d0d1fa9a7c0bafbbdb74d5882e77b554bc544f3a /init/devices.c | |
| parent | 25eab084c5bc6b6ed68001b4f67ca405fc541fcb (diff) | |
| download | system_core-6405c6953fa02d41d9f6377f4cdb947604f481c4.tar.gz system_core-6405c6953fa02d41d9f6377f4cdb947604f481c4.tar.bz2 system_core-6405c6953fa02d41d9f6377f4cdb947604f481c4.zip | |
Clean fix for the chown race condition on new input devices.
Drop init's egid to AID_INPUT while creating the device node, so that it is
created with the correct gid. This eliminates the
possibility of system_server opening the device node before its permissions
are set correctly.
Using setegid() allows us to swap back to AID_ROOT immediately after mknod().
Bug: 2375632
Diffstat (limited to 'init/devices.c')
| -rw-r--r-- | init/devices.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/init/devices.c b/init/devices.c index 55c5ee46..11328f69 100644 --- a/init/devices.c +++ b/init/devices.c @@ -306,8 +306,15 @@ static void make_device(const char *path, int block, int major, int minor) mode = get_device_perm(path, &uid, &gid) | (block ? S_IFBLK : S_IFCHR); dev = (major << 8) | minor; + /* Temporarily change egid to avoid race condition setting the gid of the + * device node. Unforunately changing the euid would prevent creation of + * some device nodes, so the uid has to be set with chown() and is still + * racy. Fixing the gid race at least fixed the issue with system_server + * opening dynamic input devices under the AID_INPUT gid. */ + setegid(gid); mknod(path, mode, dev); - chown(path, uid, gid); + chown(path, uid, -1); + setegid(AID_ROOT); } #if LOG_UEVENTS |