From: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com> Date: Wed, 24 Dec 2008 14:03:57 -0800 Subject: [PATCH 4/7][v8] Protect cinit from unblocked SIG_DFL signals
Drop early any SIG_DFL or SIG_IGN signals to container-init from within the same container. But queue SIGSTOP and SIGKILL to the container-init if they are from an ancestor container. Blocked, fatal signals (i.e when SIG_DFL is to terminate) from within the container can still terminate the container-init. That will be addressed in the next patch. Note: To be bisect-safe, SIGNAL_UNKILLABLE will be set for container-inits in a follow-on patch. Until then, this patch is just a preparatory step. Changelog[v7]: - (Oleg Nesterov) Bugfix: send_sigqueue() should use from_ancestor_ns=0 - siginfo_from_user(), siginfo_from_ancestor_ns() are needed in only one place. Remove them and move their logic into send_signal(). Seems to make code more easier to read :-) Changelog[v6]: - (Roland McGrath) Remove unnecessary helper signal_task_unkillable() and fold checks into sig_task_ignored(). Changelog[v4]: - (Oleg Nesterov) Remove SIGNAL_UNKILLABLE_FROM_NS and rename 'same_ns' to 'from_ancestor_ns'. - SIGNAL_UNKILLABLE is not yet set for container-inits (will be set in follow-on patch). Signed-off-by: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com> --- kernel/signal.c | 28 +++++++++++++++++++--------- 1 files changed, 19 insertions(+), 9 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index ff1dff9..a3a1304 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -55,20 +55,21 @@ static int sig_handler_ignored(void __user *handler, int sig) (handler == SIG_DFL && sig_kernel_ignore(sig)); } -static int sig_task_ignored(struct task_struct *t, int sig) +static int sig_task_ignored(struct task_struct *t, int sig, + int from_ancestor_ns) { void __user *handler; handler = sig_handler(t, sig); if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) && - handler == SIG_DFL) + handler == SIG_DFL && !from_ancestor_ns) return 1; return sig_handler_ignored(handler, sig); } -static int sig_ignored(struct task_struct *t, int sig) +static int sig_ignored(struct task_struct *t, int sig, int from_ancestor_ns) { /* * Blocked signals are never ignored, since the @@ -78,7 +79,7 @@ static int sig_ignored(struct task_struct *t, int sig) if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig)) return 0; - if (!sig_task_ignored(t, sig)) + if (!sig_task_ignored(t, sig, from_ancestor_ns)) return 0; /* @@ -634,7 +635,7 @@ static int check_kill_permission(int sig, struct siginfo *info, * Returns true if the signal should be actually delivered, otherwise * it should be dropped. */ -static int prepare_signal(int sig, struct task_struct *p) +static int prepare_signal(int sig, struct task_struct *p, int from_ancestor_ns) { struct signal_struct *signal = p->signal; struct task_struct *t; @@ -718,7 +719,7 @@ static int prepare_signal(int sig, struct task_struct *p) } } - return !sig_ignored(p, sig); + return !sig_ignored(p, sig, from_ancestor_ns); } /* @@ -832,7 +833,8 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t, trace_sched_signal_send(sig, t); assert_spin_locked(&t->sighand->siglock); - if (!prepare_signal(sig, t)) + + if (!prepare_signal(sig, t, from_ancestor_ns)) return 0; pending = group ? &t->signal->shared_pending : &t->pending; @@ -902,7 +904,15 @@ out_set: static int send_signal(int sig, struct siginfo *info, struct task_struct *t, int group) { - return __send_signal(sig, info, t, group, 0); + int from_ancestor_ns = 0; + +#ifdef CONFIG_PID_NS + if (!is_si_special(info) && SI_FROMUSER(info) && + task_pid_nr_ns(current, task_active_pid_ns(t)) <= 0) + from_ancestor_ns = 1; +#endif + + return __send_signal(sig, info, t, group, from_ancestor_ns); } int print_fatal_signals; @@ -1336,7 +1346,7 @@ int send_sigqueue(struct sigqueue *q, struct task_struct *t, int group) goto ret; ret = 1; /* the signal is ignored */ - if (!prepare_signal(sig, t)) + if (!prepare_signal(sig, t, 0)) goto out; ret = 0; -- 1.5.2.5 _______________________________________________ Containers mailing list contain...@lists.linux-foundation.org https://lists.linux-foundation.org/mailman/listinfo/containers _______________________________________________ Devel mailing list Devel@openvz.org https://openvz.org/mailman/listinfo/devel