4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
[ Upstream commit 3597dfe01d12f570bc739da67f857fd222a3ea66 ]
Instead of playing whack-a-mole and changing SEND_SIG_PRIV to
SEND_SIG_FORCED throughout the kernel to ensure a pid namespace init
gets signals sent by the kernel, stop allowing a pid namespace init to
ignore SIGKILL or SIGSTOP sent by the kernel. A pid namespace init is
only supposed to be able to ignore signals sent from itself and
children with SIG_DFL.
Fixes: 921cf9f63089 ("signals: protect cinit from unblocked SIG_DFL signals")
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/signal.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -991,7 +991,7 @@ static int __send_signal(int sig, struct
result = TRACE_SIGNAL_IGNORED;
if (!prepare_signal(sig, t,
- from_ancestor_ns || (info == SEND_SIG_FORCED)))
+ from_ancestor_ns || (info == SEND_SIG_PRIV) || (info == SEND_SIG_FORCED)))
goto ret;
pending = group ? &t->signal->shared_pending : &t->pending;
