linux-kernel - [PATCH 1/4] signal: give SEND_SIG_FORCED more power to beat SIGNAL

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 10 Feb 2012 21:00:21 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Anton Vorontsov <anton.vorontsov@...aro.org>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Greg KH <gregkh@...uxfoundation.org>,
	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] signal: give SEND_SIG_FORCED more power to beat
	SIGNAL_UNKILLABLE

force_sig_info() and friends have the special semantics for
synchronous signals, this interface should not be used if the
target is not current. And it needs the fixes, in particular
the clearing of SIGNAL_UNKILLABLE is not exactly right.

However there are callers which have to use force_ exactly because
it clears SIGNAL_UNKILLABLE and thus it can kill the CLONE_NEWPID
tasks, although this is almost always is wrong by various reasons.

With this patch SEND_SIG_FORCED ignores SIGNAL_UNKILLABLE, like
we do if the signal comes from the ancestor namespace.

This makes the naming in prepare_signal() paths insane, fixed by
the next cleanup.

Note: this only affects SIGKILL/SIGSTOP, but this is enough for
force_sig() abusers.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/signal.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index c73c428..bfb2b97 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1059,7 +1059,8 @@ static int __send_signal(int sig, struct siginfo *info, struct task_struct *t,

 	assert_spin_locked(&t->sighand->siglock);

-	if (!prepare_signal(sig, t, from_ancestor_ns))
+	if (!prepare_signal(sig, t,
+			from_ancestor_ns || (info == SEND_SIG_FORCED)))
 		return 0;

 	pending = group ? &t->signal->shared_pending : &t->pending;
-- 
1.5.5.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/