From: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
To: oleg@redhat.com, ebiederm@xmission.com, roland@redhat.com,
bastian@waldi.eu.org
Cc: daniel@hozac.com, xemul@openvz.org, containers@lists.osdl.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 2/6][v5] Protect init from unwanted signals more
Date: Sat, 27 Dec 2008 12:51:53 -0800 [thread overview]
Message-ID: <20081227205153.GA27337@us.ibm.com> (raw)
In-Reply-To: <20081227204658.GA27197@us.ibm.com>
From: Oleg Nesterov <oleg@redhat.com>
Date: Wed, 24 Dec 2008 13:35:23 -0800
Subject: [PATCH 2/6][v5] Protect init from unwanted signals more
(This is a modified version of the patch submitted by Oleg Nesterov
http://lkml.org/lkml/2008/11/18/249 and tries to address comments
that came up in that discussion)
init ignores the SIG_DFL signals but we queue them anyway, including
SIGKILL. This is mostly OK, the signal will be dropped silently when
dequeued, but the pending SIGKILL has 2 bad implications:
- it implies fatal_signal_pending(), so we confuse things
like wait_for_completion_killable/lock_page_killable.
- for the sub-namespace inits, the pending SIGKILL can
mask (legacy_queue) the subsequent SIGKILL from the
parent namespace which must kill cinit reliably.
(preparation, cinits don't have SIGNAL_UNKILLABLE yet)
The patch can't help when init is ptraced, but ptracing of init is
not "safe" anyway.
Changelog[v5]:
- (Oleg Nesterov) Remove SIG_IGN check in sig_task_ignored()
and let sig_handler_ignored() check SIG_IGN.
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: Roland McGrath <roland@redhat.com>
---
kernel/signal.c | 16 +++++++++++++---
1 files changed, 13 insertions(+), 3 deletions(-)
diff --git a/kernel/signal.c b/kernel/signal.c
index 7945e71..30b9c5c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -53,10 +53,21 @@ static int sig_handler_ignored(void __user *handler, int sig)
(handler == SIG_DFL && sig_kernel_ignore(sig));
}
-static int sig_ignored(struct task_struct *t, int sig)
+static int sig_task_ignored(struct task_struct *t, int sig)
{
void __user *handler;
+ handler = sig_handler(t, sig);
+
+ if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&
+ handler == SIG_DFL)
+ return 1;
+
+ return sig_handler_ignored(handler, sig);
+}
+
+static int sig_ignored(struct task_struct *t, int sig)
+{
/*
* Blocked signals are never ignored, since the
* signal handler may change by the time it is
@@ -65,8 +76,7 @@ static int sig_ignored(struct task_struct *t, int sig)
if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
return 0;
- handler = sig_handler(t, sig);
- if (!sig_handler_ignored(handler, sig))
+ if (!sig_task_ignored(t, sig))
return 0;
/*
--
1.5.2.5
next prev parent reply other threads:[~2008-12-27 20:53 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-27 20:46 [PATCH 0/6][v5]: Container-init signal semantics Sukadev Bhattiprolu
2008-12-27 20:49 ` [PATCH 1/6][v5] Remove 'handler' parameter to tracehook functions Sukadev Bhattiprolu
2008-12-27 20:51 ` Sukadev Bhattiprolu [this message]
2008-12-27 20:52 ` [PATCH 3/6][v5] Define siginfo_from_ancestor_ns() Sukadev Bhattiprolu
2008-12-31 0:12 ` Roland McGrath
2009-01-05 12:42 ` Oleg Nesterov
2009-01-05 14:33 ` Oleg Nesterov
2008-12-27 20:53 ` [PATCH 4/6][v5] Protect cinit from unblocked SIG_DFL signals Sukadev Bhattiprolu
2008-12-31 0:19 ` Roland McGrath
2009-01-05 13:24 ` Oleg Nesterov
2008-12-27 20:54 ` [PATCH 5/6][v5] Protect cinit from blocked fatal signals Sukadev Bhattiprolu
2009-01-05 15:16 ` Oleg Nesterov
2008-12-27 20:55 ` [PATCH 6/6][v5] SI_USER: Masquerade si_pid when crossing pid ns boundary Sukadev Bhattiprolu
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