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authorOleg Nesterov <oleg@redhat.com>2015-11-06 16:30:06 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-06 17:50:42 -0800
commit54708d2858e79a2bdda10bf8a20c80eb96c20613 (patch)
tree4228afc090f3a84482ec6a039b06e3769c0ee1a1 /fs/proc/fd.c
parent3a49f3d2a10dfb27411d321900197a3d6c52405b (diff)
proc: actually make proc_fd_permission() thread-friendly
The commit 96d0df79f264 ("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: 96d0df79f264 ("proc: make proc_fd_permission() thread-friendly") Reported-by: "Jin, Yihua" <yihua.jin@intel.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc/fd.c')
-rw-r--r--fs/proc/fd.c14
1 files changed, 11 insertions, 3 deletions
diff --git a/fs/proc/fd.c b/fs/proc/fd.c
index 6e5fcd00733e..3c2a915c695a 100644
--- a/fs/proc/fd.c
+++ b/fs/proc/fd.c
@@ -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;
}