>From 4ea8f0b4ae48da5f18d44b68ce3634408c89f230 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx> Date: Tue, 25 Nov 2008 10:29:10 -0800 Subject: [PATCH 4/5] Protect cinit from fatal signals To protect container-init from fatal signals, set SIGNAL_UNKILLABLE but clear it if it receives SIGKILL from parent namespace - so it is still killable from ancestor namespace. Note that container-init is still somewhat special compared to 'normal processes' - unhandled fatal signals like SIGUSR1 to a container-init are dropped even if they are from ancestor namespace. SIGKILL from an ancestor namespace is the only reliable way to kill a container-init. Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx> --- kernel/fork.c | 2 ++ kernel/signal.c | 2 ++ 2 files changed, 4 insertions(+), 0 deletions(-) diff --git a/kernel/fork.c b/kernel/fork.c index 28be39a..368f25c 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -814,6 +814,8 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) atomic_set(&sig->live, 1); init_waitqueue_head(&sig->wait_chldexit); sig->flags = 0; + if (clone_flags & CLONE_NEWPID) + sig->flags |= SIGNAL_UNKILLABLE; sig->group_exit_code = 0; sig->group_exit_task = NULL; sig->group_stop_count = 0; diff --git a/kernel/signal.c b/kernel/signal.c index 45aebf0..8c294c1 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -828,6 +828,8 @@ static int send_signal(int sig, struct siginfo *info, struct task_struct *t, trace_sched_signal_send(sig, t); from_ancestor_ns = siginfo_from_ancestor_ns(t, info); + if (from_ancestor_ns && sig == SIGKILL) + t->signal->flags &= ~SIGNAL_UNKILLABLE; assert_spin_locked(&t->sighand->siglock); if (!prepare_signal(sig, t)) -- 1.5.2.5 _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers
