Subject: [merged] proc-make-proc_fd_permission-thread-friendly.patch removed from -mm tree To: oleg@xxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Thu, 12 Sep 2013 12:48:35 -0700 The patch titled Subject: proc: make proc_fd_permission() thread-friendly has been removed from the -mm tree. Its filename was proc-make-proc_fd_permission-thread-friendly.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Oleg Nesterov <oleg@xxxxxxxxxx> Subject: proc: make proc_fd_permission() thread-friendly proc_fd_permission() says "process can still access /proc/self/fd after it has executed a setuid()", but the "task_pid() = proc_pid() check only helps if the task is group leader, /proc/self points to /proc/<leader-pid>. Change this check to use task_tgid() so that the whole thread group can access its /proc/self/fd or /proc/<tid-of-sub-thread>/fd. Notes: - CLONE_THREAD does not require CLONE_FILES so task->files can differ, but I don't think this can lead to any security problem. And this matches same_thread_group() in __ptrace_may_access(). - /proc/self should probably point to /proc/<thread-tid>, but it is too late to change the rules. Perhaps it makes sense to add /proc/thread though. Test-case: void *tfunc(void *arg) { assert(opendir("/proc/self/fd")); return NULL; } int main(void) { pthread_t t; pthread_create(&t, NULL, tfunc, NULL); pthread_join(t, NULL); return 0; } fails if, say, this executable is not readable and suid_dumpable = 0. Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/fd.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN fs/proc/fd.c~proc-make-proc_fd_permission-thread-friendly fs/proc/fd.c --- a/fs/proc/fd.c~proc-make-proc_fd_permission-thread-friendly +++ a/fs/proc/fd.c @@ -286,7 +286,7 @@ int proc_fd_permission(struct inode *ino int rv = generic_permission(inode, mask); if (rv == 0) return 0; - if (task_pid(current) == proc_pid(inode)) + if (task_tgid(current) == proc_pid(inode)) rv = 0; return rv; } _ Patches currently in -mm which might be from oleg@xxxxxxxxxx are origin.patch anon_inodefs-forbid-open-via-proc.patch autofs4-allow-autofs-to-work-outside-the-initial-pid-namespace.patch autofs4-translate-pids-to-the-right-namespace-for-the-daemon.patch signals-eventpoll-set-saved_sigmask-at-the-start.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html