From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4AAFFC38A2A for ; Fri, 8 May 2020 18:48:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 254CB20731 for ; Fri, 8 May 2020 18:48:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727815AbgEHSsy (ORCPT ); Fri, 8 May 2020 14:48:54 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:54612 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726864AbgEHSsx (ORCPT ); Fri, 8 May 2020 14:48:53 -0400 Received: from in01.mta.xmission.com ([166.70.13.51]) by out01.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1jX83I-0005SA-Sr; Fri, 08 May 2020 12:48:52 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=x220.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.87) (envelope-from ) id 1jX83I-0002xa-4g; Fri, 08 May 2020 12:48:52 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Cc: Linus Torvalds , Oleg Nesterov , Jann Horn , Kees Cook , Greg Ungerer , Rob Landley , Bernd Edlinger , , Al Viro , Alexey Dobriyan , Andrew Morton References: <87h7wujhmz.fsf@x220.int.ebiederm.org> <87sgga6ze4.fsf@x220.int.ebiederm.org> Date: Fri, 08 May 2020 13:45:25 -0500 In-Reply-To: <87sgga6ze4.fsf@x220.int.ebiederm.org> (Eric W. Biederman's message of "Fri, 08 May 2020 13:43:31 -0500") Message-ID: <87blmy6zay.fsf_-_@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1jX83I-0002xa-4g;;;mid=<87blmy6zay.fsf_-_@x220.int.ebiederm.org>;;;hst=in01.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1/M8xbipLE7+kJXgkEYUSylu3e6cNqDnCs= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: [PATCH 3/6] exec: Stop open coding mutex_lock_killable of cred_guard_mutex X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Oleg modified the code that did "mutex_lock_interruptible(¤t->cred_guard_mutex)" to return -ERESTARTNOINTR instead of -EINTR, so that userspace will never see a failure to grab the mutex. Slightly earlier Liam R. Howlett defined mutex_lock_killable for exactly the same situation but it does it a little more cleanly. Switch the code to mutex_lock_killable so that it is clearer what the code is doing. Ref: ad776537cc6b ("Add mutex_lock_killable") Ref: 793285fcafce ("cred_guard_mutex: do not return -EINTR to user-space") Signed-off-by: "Eric W. Biederman" --- fs/exec.c | 5 +++-- kernel/ptrace.c | 4 ++-- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 82106241ed53..11a5c073aa35 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1493,8 +1493,9 @@ EXPORT_SYMBOL(finalize_exec); */ static int prepare_bprm_creds(struct linux_binprm *bprm) { - if (mutex_lock_interruptible(¤t->signal->cred_guard_mutex)) - return -ERESTARTNOINTR; + int retval = mutex_lock_killable(¤t->signal->cred_guard_mutex); + if (retval) + return retval; bprm->cred = prepare_exec_creds(); if (likely(bprm->cred)) diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 43d6179508d6..1876b3392488 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -391,8 +391,8 @@ static int ptrace_attach(struct task_struct *task, long request, * SUID, SGID and LSM creds get determined differently * under ptrace. */ - retval = -ERESTARTNOINTR; - if (mutex_lock_interruptible(&task->signal->cred_guard_mutex)) + retval = mutex_lock_killable(&task->signal->cred_guard_mutex); + if (retval) goto out; task_lock(task); -- 2.20.1