diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2015-11-07 03:30:06 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-02-20 01:28:23 +0300 |
| commit | a793d2b5bc0b1d6dcac2e2ad1d5f39bd47a6a234 (patch) | |
| tree | 21066f7967c95e3d241e9c7586a24b1d83c2d7fa | |
| parent | 788e6ddf4d9816185d857c34b763d26945bdcd4b (diff) | |
| download | linux-a793d2b5bc0b1d6dcac2e2ad1d5f39bd47a6a234.tar.xz | |
proc: actually make proc_fd_permission() thread-friendly
commit 54708d2858e79a2bdda10bf8a20c80eb96c20613 upstream.
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | fs/proc/fd.c | 14 |
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; } |