From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755400AbbILXMb (ORCPT ); Sat, 12 Sep 2015 19:12:31 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:9234 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754978AbbILXMR (ORCPT ); Sat, 12 Sep 2015 19:12:17 -0400 Message-Id: <20150912225607.941846866@1wt.eu> User-Agent: quilt/0.63-1 Date: Sun, 13 Sep 2015 00:56:38 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Mark Grondona , Ben Woodard , Oleg Nesterov , Andrew Morton , Linus Torvalds , Ben Hutchings , Sheng Yong , Willy Tarreau Subject: [PATCH 2.6.32 32/62] __ptrace_may_access() should not deny sub-threads MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 In-Reply-To: <08d3b586eb2e764308c3de9ee398a17c@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Mark Grondona commit 73af963f9f3036dffed55c3a2898598186db1045 upstream. __ptrace_may_access() checks get_dumpable/ptrace_has_cap/etc if task != current, this can can lead to surprising results. For example, a sub-thread can't readlink("/proc/self/exe") if the executable is not readable. setup_new_exec()->would_dump() notices that inode_permission(MAY_READ) fails and then it does set_dumpable(suid_dumpable). After that get_dumpable() fails. (It is not clear why proc_pid_readlink() checks get_dumpable(), perhaps we could add PTRACE_MODE_NODUMPABLE) Change __ptrace_may_access() to use same_thread_group() instead of "task == current". Any security check is pointless when the tasks share the same ->mm. Signed-off-by: Mark Grondona Signed-off-by: Ben Woodard Signed-off-by: Oleg Nesterov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings Cc: Sheng Yong (cherry picked from commit f062bd6e420a064a19563b80c26d746b0262e404) Signed-off-by: Willy Tarreau --- kernel/ptrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 03da336..426b0c8 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -169,7 +169,7 @@ int __ptrace_may_access(struct task_struct *task, unsigned int mode) */ int dumpable = 0; /* Don't let security modules deny introspection */ - if (task == current) + if (same_thread_group(task, current)) return 0; rcu_read_lock(); tcred = __task_cred(task); -- 1.7.12.2.21.g234cd45.dirty