Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753932Ab1C1VNo (ORCPT ); Mon, 28 Mar 2011 17:13:44 -0400 Received: from na3sys010aog114.obsmtp.com ([74.125.245.96]:51048 "HELO na3sys010aog114.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751276Ab1C1VNn (ORCPT ); Mon, 28 Mar 2011 17:13:43 -0400 From: Roland Dreier To: Linus Torvalds Cc: linux-kernel@vger.kernel.org, Oleg Nesterov , Julien Tinnes , Klaus Dittrich Subject: [PATCH v2] Relax si_code check in rt_sigqueueinfo and rt_tgsigqueueinfo Date: Mon, 28 Mar 2011 14:13:35 -0700 Message-Id: <1301346815-6755-1-git-send-email-roland@kernel.org> X-Mailer: git-send-email 1.7.4.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2248 Lines: 53 From: Roland Dreier Commit da48524eb206 ("Prevent rt_sigqueueinfo and rt_tgsigqueueinfo from spoofing the signal code") made the check on si_code too strict. There are several legitimate places where glibc wants to queue a negative si_code different from SI_QUEUE: - This was first noticed with glibc's aio implementation, which wants to queue a signal with si_code SI_ASYNCIO; the current kernel causes glibc's tst-aio4 test to fail because rt_sigqueueinfo() fails with EPERM. - Further examination of the glibc source shows that getaddrinfo_a() wants to use SI_ASYNCNL (which the kernel does not even define). The timer_create() fallback code wants to queue signals with SI_TIMER. As suggested by Oleg Nesterov , loosen the check to forbid only the problematic SI_TKILL case. Reported-by: Klaus Dittrich Cc: Signed-off-by: Roland Dreier --- kernel/signal.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/signal.c b/kernel/signal.c index 324eff5..b2bfa3a 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -2437,7 +2437,7 @@ SYSCALL_DEFINE3(rt_sigqueueinfo, pid_t, pid, int, sig, /* Not even root can pretend to send signals from the kernel. * Nor can they impersonate a kill()/tgkill(), which adds source info. */ - if (info.si_code != SI_QUEUE) { + if (info.si_code >= 0 || info.si_code == SI_TKILL) { /* We used to allow any < 0 si_code */ WARN_ON_ONCE(info.si_code < 0); return -EPERM; @@ -2457,7 +2457,7 @@ long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info) /* Not even root can pretend to send signals from the kernel. * Nor can they impersonate a kill()/tgkill(), which adds source info. */ - if (info->si_code != SI_QUEUE) { + if (info->si_code >= 0 || info->si_code == SI_TKILL) { /* We used to allow any < 0 si_code */ WARN_ON_ONCE(info->si_code < 0); return -EPERM; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/