Messages in this thread Patch in this message | | | Date | Tue, 6 Jan 2009 23:51:44 -0800 | From | Sukadev Bhattiprolu <> | Subject | [PATCH 5/7][v6] Protect cinit from unblocked SIG_DFL signals |
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From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com> Date: Wed, 24 Dec 2008 14:03:57 -0800 Subject: [PATCH 5/7][v6] 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[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 <sukadev@linux.vnet.ibm.com> --- kernel/signal.c | 24 +++++++++++++++--------- 1 files changed, 15 insertions(+), 9 deletions(-)
diff --git a/kernel/signal.c b/kernel/signal.c index d0dfa0d..3156dab 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -53,20 +53,21 @@ 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 @@ -76,7 +77,7 @@ 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; /* @@ -632,7 +633,7 @@ 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; @@ -716,7 +717,7 @@ static int prepare_signal(int sig, struct task_struct *p) } } - return !sig_ignored(p, sig); + return !sig_ignored(p, sig, from_ancestor_ns); } /* @@ -867,7 +868,8 @@ 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; @@ -936,7 +938,11 @@ 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; + + from_ancestor_ns = siginfo_from_ancestor_ns(t, info); + + return __send_signal(sig, info, t, group, from_ancestor_ns); } int print_fatal_signals; @@ -1368,7 +1374,7 @@ 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, 1)) goto out; ret = 0; -- 1.5.2.5
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