From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail177-1.suw61.mandrillapp.com ([198.2.177.1]:27939 "EHLO mail177-1.suw61.mandrillapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932296AbcCAX5r (ORCPT ); Tue, 1 Mar 2016 18:57:47 -0500 Received: from pmta06.mandrill.prod.suw01.rsglab.com (127.0.0.1) by mail177-1.suw61.mandrillapp.com id hqom7m22rtk6 for ; Tue, 1 Mar 2016 23:55:12 +0000 (envelope-from ) From: Greg Kroah-Hartman Subject: [PATCH 4.4 262/342] seccomp: always propagate NO_NEW_PRIVS on tsync To: Cc: Greg Kroah-Hartman , , Jann Horn , Kees Cook Message-Id: <20160301234536.368544446@linuxfoundation.org> In-Reply-To: <20160301234527.990448862@linuxfoundation.org> References: <20160301234527.990448862@linuxfoundation.org> Date: Tue, 01 Mar 2016 23:55:12 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jann Horn commit 103502a35cfce0710909da874f092cb44823ca03 upstream. Before this patch, a process with some permissive seccomp filter that was applied by root without NO_NEW_PRIVS was able to add more filters to itself without setting NO_NEW_PRIVS by setting the new filter from a throwaway thread with NO_NEW_PRIVS. Signed-off-by: Jann Horn Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman --- kernel/seccomp.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -316,24 +316,24 @@ static inline void seccomp_sync_threads( put_seccomp_filter(thread); smp_store_release(&thread->seccomp.filter, caller->seccomp.filter); + + /* + * Don't let an unprivileged task work around + * the no_new_privs restriction by creating + * a thread that sets it up, enters seccomp, + * then dies. + */ + if (task_no_new_privs(caller)) + task_set_no_new_privs(thread); + /* * Opt the other thread into seccomp if needed. * As threads are considered to be trust-realm * equivalent (see ptrace_may_access), it is safe to * allow one thread to transition the other. */ - if (thread->seccomp.mode == SECCOMP_MODE_DISABLED) { - /* - * Don't let an unprivileged task work around - * the no_new_privs restriction by creating - * a thread that sets it up, enters seccomp, - * then dies. - */ - if (task_no_new_privs(caller)) - task_set_no_new_privs(thread); - + if (thread->seccomp.mode == SECCOMP_MODE_DISABLED) seccomp_assign_mode(thread, SECCOMP_MODE_FILTER); - } } }