Doug / smarc-fsl-linux-kernel

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Commit 5e1182deb81ae8c68494017c4a8a71811659c870

Authored by Eric W. Biederman
1 parent 0a01f2cc39
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

pidns: Don't allow new processes in a dead pid namespace. 

Set nr_hashed to -1 just before we schedule the work to cleanup proc.
Test nr_hashed just before we hash a new pid and if nr_hashed is < 0
fail.

This guaranteees that processes never enter a pid namespaces after we
have cleaned up the state to support processes in a pid namespace.

Currently sending SIGKILL to all of the process in a pid namespace as
init exists gives us this guarantee but we need something a little
stronger to support unsharing and joining a pid namespace.

Acked-by: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

Showing 1 changed file with 7 additions and 1 deletions Side-by-side Diff

... ... @@ -274,8 +274,10 @@
274 274 for (i = 0; i <= pid->level; i++) {
275 275 struct upid *upid = pid->numbers + i;
276 276 hlist_del_rcu(&upid->pid_chain);
277   - if (--upid->ns->nr_hashed == 0)
  277 + if (--upid->ns->nr_hashed == 0) {
  278 + upid->ns->nr_hashed = -1;
278 279 schedule_work(&upid->ns->proc_work);
  280 + }
279 281 }
280 282 spin_unlock_irqrestore(&pidmap_lock, flags);
281 283  
... ... @@ -321,6 +323,8 @@
321 323  
322 324 upid = pid->numbers + ns->level;
323 325 spin_lock_irq(&pidmap_lock);
  326 + if (ns->nr_hashed < 0)
  327 + goto out_unlock;
324 328 for ( ; upid >= pid->numbers; --upid) {
325 329 hlist_add_head_rcu(&upid->pid_chain,
326 330 &pid_hash[pid_hashfn(upid->nr, upid->ns)]);
... ... @@ -331,6 +335,8 @@
331 335 out:
332 336 return pid;
333 337  
  338 +out_unlock:
  339 + spin_unlock(&pidmap_lock);
334 340 out_free:
335 341 while (++i <= ns->level)
336 342 free_pidmap(pid->numbers + i);