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Commit 54708d28 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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proc: actually make proc_fd_permission() thread-friendly 



The commit 96d0df79 ("proc: make proc_fd_permission() thread-friendly")
fixed the access to /proc/self/fd from sub-threads, but introduced another
problem: a sub-thread can't access /proc/<tid>/fd/ or /proc/thread-self/fd
if generic_permission() fails.

Change proc_fd_permission() to check same_thread_group(pid_task(), current).

Fixes: 96d0df79 ("proc: make proc_fd_permission() thread-friendly")
Reported-by: default avatar"Jin, Yihua" <yihua.jin@intel.com>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3a49f3d2

fs/proc/fd.c

+11 −3
Original line number Diff line number Diff line
@@ -291,11 +291,19 @@ static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry, 
 */

int proc_fd_permission(struct inode *inode, int mask)

{

	int rv = generic_permission(inode, mask);

	struct task_struct *p;

	int rv;



	rv = generic_permission(inode, mask);

	if (rv == 0)

		return 0;

	if (task_tgid(current) == proc_pid(inode))

		return rv;



	rcu_read_lock();

	p = pid_task(proc_pid(inode), PIDTYPE_PID);

	if (p && same_thread_group(p, current))

		rv = 0;

	rcu_read_unlock();



	return rv;

}