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| author | Eric W. Biederman <ebiederm@xmission.com> | 2010-07-12 18:50:25 -0700 |
|---|---|---|
| committer | Eric W. Biederman <ebiederm@xmission.com> | 2012-11-19 05:59:11 -0800 |
| commit | 5e1182deb81ae8c68494017c4a8a71811659c870 (patch) | |
| tree | 81b9fa941a3293f6d5fa4e32aa311988bb3bf985 /kernel/pid.c | |
| parent | 0a01f2cc390e10633a54f72c608cc3fe19a50c3d (diff) | |
| download | linux-5e1182deb81ae8c68494017c4a8a71811659c870.tar.bz2 | |
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>
Diffstat (limited to 'kernel/pid.c')
| -rw-r--r-- | kernel/pid.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/pid.c b/kernel/pid.c index e957f8b09136..9c219117af36 100644 --- a/kernel/pid.c +++ b/kernel/pid.c @@ -274,8 +274,10 @@ void free_pid(struct pid *pid) for (i = 0; i <= pid->level; i++) { struct upid *upid = pid->numbers + i; hlist_del_rcu(&upid->pid_chain); - if (--upid->ns->nr_hashed == 0) + if (--upid->ns->nr_hashed == 0) { + upid->ns->nr_hashed = -1; schedule_work(&upid->ns->proc_work); + } } spin_unlock_irqrestore(&pidmap_lock, flags); @@ -321,6 +323,8 @@ struct pid *alloc_pid(struct pid_namespace *ns) upid = pid->numbers + ns->level; spin_lock_irq(&pidmap_lock); + if (ns->nr_hashed < 0) + goto out_unlock; for ( ; upid >= pid->numbers; --upid) { hlist_add_head_rcu(&upid->pid_chain, &pid_hash[pid_hashfn(upid->nr, upid->ns)]); @@ -331,6 +335,8 @@ struct pid *alloc_pid(struct pid_namespace *ns) out: return pid; +out_unlock: + spin_unlock(&pidmap_lock); out_free: while (++i <= ns->level) free_pidmap(pid->numbers + i); |