From patchwork Tue Jan 28 14:00:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 232729 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT 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 A1C5BC33CB3 for ; Tue, 28 Jan 2020 14:05:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 774B424688 for ; Tue, 28 Jan 2020 14:05:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580220337; bh=QSz8di9SiAQmgzt/sME1SyMBDIqd/2K83kwnMee01gM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=dEaCqSMBqWct11mdgqMshqiRlWg+6CuCal1rA++CtBexwK6RD50Qf8PEfpgM0ctgu yi7xMAh+FfGJ7fwwv49kRDfFIZhmzhIhwmHwAMFckkJv+niI5LegS/G4qiN+QThRON f0jBBsPnMFA5rKGqHgRscXNjg+kjRlnW/BHJ2B28= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728302AbgA1OFe (ORCPT ); Tue, 28 Jan 2020 09:05:34 -0500 Received: from mail.kernel.org ([198.145.29.99]:53222 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728299AbgA1OFd (ORCPT ); Tue, 28 Jan 2020 09:05:33 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 547642468D; Tue, 28 Jan 2020 14:05:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1580220332; bh=QSz8di9SiAQmgzt/sME1SyMBDIqd/2K83kwnMee01gM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=J2eFQa3DqKisxXb8/118g8azk8p/zQCmXG2eeFx6bRvuHlPiNdojhDpdj7aq13wV7 ++eEhZtJzNKlbgavSfObTvlO2GpPDrSLrkqYFT9o0iqbakoH8iXhDlGLeTX6Y/QTkC QNT8FgBfe7TJP5im6iHNmTOiBMD/qnWU6RkcPbzE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Al Viro Subject: [PATCH 5.4 085/104] do_last(): fetch directory ->i_mode and ->i_uid before its too late Date: Tue, 28 Jan 2020 15:00:46 +0100 Message-Id: <20200128135828.911339466@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200128135817.238524998@linuxfoundation.org> References: <20200128135817.238524998@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Al Viro commit d0cb50185ae942b03c4327be322055d622dc79f6 upstream. may_create_in_sticky() call is done when we already have dropped the reference to dir. Fixes: 30aba6656f61e (namei: allow restricted O_CREAT of FIFOs and regular files) Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/namei.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) --- a/fs/namei.c +++ b/fs/namei.c @@ -1001,7 +1001,8 @@ static int may_linkat(struct path *link) * may_create_in_sticky - Check whether an O_CREAT open in a sticky directory * should be allowed, or not, on files that already * exist. - * @dir: the sticky parent directory + * @dir_mode: mode bits of directory + * @dir_uid: owner of directory * @inode: the inode of the file to open * * Block an O_CREAT open of a FIFO (or a regular file) when: @@ -1017,18 +1018,18 @@ static int may_linkat(struct path *link) * * Returns 0 if the open is allowed, -ve on error. */ -static int may_create_in_sticky(struct dentry * const dir, +static int may_create_in_sticky(umode_t dir_mode, kuid_t dir_uid, struct inode * const inode) { if ((!sysctl_protected_fifos && S_ISFIFO(inode->i_mode)) || (!sysctl_protected_regular && S_ISREG(inode->i_mode)) || - likely(!(dir->d_inode->i_mode & S_ISVTX)) || - uid_eq(inode->i_uid, dir->d_inode->i_uid) || + likely(!(dir_mode & S_ISVTX)) || + uid_eq(inode->i_uid, dir_uid) || uid_eq(current_fsuid(), inode->i_uid)) return 0; - if (likely(dir->d_inode->i_mode & 0002) || - (dir->d_inode->i_mode & 0020 && + if (likely(dir_mode & 0002) || + (dir_mode & 0020 && ((sysctl_protected_fifos >= 2 && S_ISFIFO(inode->i_mode)) || (sysctl_protected_regular >= 2 && S_ISREG(inode->i_mode))))) { return -EACCES; @@ -3248,6 +3249,8 @@ static int do_last(struct nameidata *nd, struct file *file, const struct open_flags *op) { struct dentry *dir = nd->path.dentry; + kuid_t dir_uid = dir->d_inode->i_uid; + umode_t dir_mode = dir->d_inode->i_mode; int open_flag = op->open_flag; bool will_truncate = (open_flag & O_TRUNC) != 0; bool got_write = false; @@ -3383,7 +3386,7 @@ finish_open: error = -EISDIR; if (d_is_dir(nd->path.dentry)) goto out; - error = may_create_in_sticky(dir, + error = may_create_in_sticky(dir_mode, dir_uid, d_backing_inode(nd->path.dentry)); if (unlikely(error)) goto out;