4.19-stable review patch. If anyone has any objections, please let me know.
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From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
commit ada1986d07976d60bed5017aa38b7f7cf27883f7 upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- security/tomoyo/domain.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/security/tomoyo/domain.c +++ b/security/tomoyo/domain.c @@ -701,10 +701,13 @@ int tomoyo_find_next_domain(struct linux 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. */