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| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2024-09-25 22:30:59 +0900 |
|---|---|---|
| committer | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2024-09-25 22:30:59 +0900 |
| commit | ada1986d07976d60bed5017aa38b7f7cf27883f7 (patch) | |
| tree | ffab9421a37081fca369d2421c6f5105f7650912 /security | |
| parent | 8b985bbfabbe46c8b9200d7d299030232c8ebd05 (diff) | |
| download | lwn-ada1986d07976d60bed5017aa38b7f7cf27883f7.tar.gz lwn-ada1986d07976d60bed5017aa38b7f7cf27883f7.zip | |
tomoyo: fallback to realpath if symlink's pathname does not exist
Alfred Agrell found that TOMOYO cannot handle execveat(AT_EMPTY_PATH)
inside chroot environment where /dev and /proc are not mounted, for
commit 51f39a1f0cea ("syscalls: implement execveat() system call") missed
that TOMOYO tries to canonicalize argv[0] when the filename fed to the
executed program as argv[0] is supplied using potentially nonexistent
pathname.
Since "/dev/fd/<fd>" already lost symlink information used for obtaining
that <fd>, it is too late to reconstruct symlink's pathname. Although
<filename> part of "/dev/fd/<fd>/<filename>" might not be canonicalized,
TOMOYO cannot use tomoyo_realpath_nofollow() when /dev or /proc is not
mounted. Therefore, fallback to tomoyo_realpath_from_path() when
tomoyo_realpath_nofollow() failed.
Reported-by: Alfred Agrell <blubban@gmail.com>
Closes: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1082001
Fixes: 51f39a1f0cea ("syscalls: implement execveat() system call")
Cc: stable@vger.kernel.org # v3.19+
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Diffstat (limited to 'security')
| -rw-r--r-- | security/tomoyo/domain.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c index 90b53500a236..aed9e3ef2c9e 100644 --- a/security/tomoyo/domain.c +++ b/security/tomoyo/domain.c @@ -723,10 +723,13 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm) ee->r.obj = &ee->obj; ee->obj.path1 = bprm->file->f_path; /* Get symlink's pathname of program. */ - retval = -ENOENT; exename.name = tomoyo_realpath_nofollow(original_name); - if (!exename.name) - goto out; + if (!exename.name) { + /* Fallback to realpath if symlink's pathname does not exist. */ + exename.name = tomoyo_realpath_from_path(&bprm->file->f_path); + if (!exename.name) + goto out; + } tomoyo_fill_path_info(&exename); retry: /* Check 'aggregator' directive. */ |