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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 A8266C71122 for ; Sun, 14 Oct 2018 15:54:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 767CA20645 for ; Sun, 14 Oct 2018 15:54:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 767CA20645 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729107AbeJNXfu (ORCPT ); Sun, 14 Oct 2018 19:35:50 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:36089 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727792AbeJNXL4 (ORCPT ); Sun, 14 Oct 2018 19:11:56 -0400 Received: from [2a02:8011:400e:2:cbab:f00:c93f:614] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1gBiLi-0004cF-Vf; Sun, 14 Oct 2018 16:30:35 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gBiLZ-0000hw-TH; Sun, 14 Oct 2018 16:30:25 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Jonathan Billings" , "David Howells" Date: Sun, 14 Oct 2018 16:25:41 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 325/366] afs: Fix directory permissions check In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:cbab:f00:c93f:614 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.60-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: David Howells commit 378831e4daec75fbba6d3612bcf3b4dd00ddbf08 upstream. Doing faccessat("/afs/some/directory", 0) triggers a BUG in the permissions check code. Fix this by just removing the BUG section. If no permissions are asked for, just return okay if the file exists. Also: (1) Split up the directory check so that it has separate if-statements rather than if-else-if (e.g. checking for MAY_EXEC shouldn't skip the check for MAY_READ and MAY_WRITE). (2) Check for MAY_CHDIR as MAY_EXEC. Without the main fix, the following BUG may occur: kernel BUG at fs/afs/security.c:386! invalid opcode: 0000 [#1] SMP PTI ... RIP: 0010:afs_permission+0x19d/0x1a0 [kafs] ... Call Trace: ? inode_permission+0xbe/0x180 ? do_faccessat+0xdc/0x270 ? do_syscall_64+0x60/0x1f0 ? entry_SYSCALL_64_after_hwframe+0x49/0xbe Fixes: 00d3b7a4533e ("[AFS]: Add security support.") Reported-by: Jonathan Billings Signed-off-by: David Howells Signed-off-by: Ben Hutchings --- fs/afs/security.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) --- a/fs/afs/security.c +++ b/fs/afs/security.c @@ -323,18 +323,14 @@ int afs_permission(struct inode *inode, mask, access, S_ISDIR(inode->i_mode) ? "dir" : "file"); if (S_ISDIR(inode->i_mode)) { - if (mask & MAY_EXEC) { + if (mask & (MAY_EXEC | MAY_READ | MAY_CHDIR)) { if (!(access & AFS_ACE_LOOKUP)) goto permission_denied; - } else if (mask & MAY_READ) { - if (!(access & AFS_ACE_LOOKUP)) - goto permission_denied; - } else if (mask & MAY_WRITE) { + } + if (mask & MAY_WRITE) { if (!(access & (AFS_ACE_DELETE | /* rmdir, unlink, rename from */ AFS_ACE_INSERT))) /* create, mkdir, symlink, rename to */ goto permission_denied; - } else { - BUG(); } } else { if (!(access & AFS_ACE_LOOKUP))