From patchwork Wed May 5 12:04:34 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 431612 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, 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 13626C43461 for ; Wed, 5 May 2021 12:05:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E8F37613F1 for ; Wed, 5 May 2021 12:05:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233242AbhEEMGJ (ORCPT ); Wed, 5 May 2021 08:06:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:43662 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233210AbhEEMGD (ORCPT ); Wed, 5 May 2021 08:06:03 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 75609613C7; Wed, 5 May 2021 12:05:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620216306; bh=tXMUTu1rnFSD++a6OT0XEi5g7gClM4msz7mTdIGtgTc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=T7oYGKuLDeTzYoW7LmixgO2KyeY8Xwh0+4+ckYyrKMit8OWOs01YTwXAI4I6nyiJD tAPe/6kgh46uuZc3usQCOf4kruipfkVUYV7ta27lCjYAuSE+ZRXMZ/NM/9mdWJg0/V FoN1t9fOwjjRqcn5fuIqSHRi1nYI+UXpzI1WJDTw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Miklos Szeredi Subject: [PATCH 5.4 20/21] ovl: allow upperdir inside lowerdir Date: Wed, 5 May 2021 14:04:34 +0200 Message-Id: <20210505112325.389627823@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210505112324.729798712@linuxfoundation.org> References: <20210505112324.729798712@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Miklos Szeredi commit 708fa01597fa002599756bf56a96d0de1677375c upstream. Commit 146d62e5a586 ("ovl: detect overlapping layers") made sure we don't have overlapping layers, but it also broke the arguably valid use case of mount -olowerdir=/,upperdir=/subdir,.. where upperdir overlaps lowerdir on the same filesystem. This has been causing regressions. Revert the check, but only for the specific case where upperdir and/or workdir are subdirectories of lowerdir. Any other overlap (e.g. lowerdir is subdirectory of upperdir, etc) case is crazy, so leave the check in place for those. Overlaps are detected at lookup time too, so reverting the mount time check should be safe. Fixes: 146d62e5a586 ("ovl: detect overlapping layers") Cc: # v5.2 Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/super.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -1525,7 +1525,8 @@ out_err: * - upper/work dir of any overlayfs instance */ static int ovl_check_layer(struct super_block *sb, struct ovl_fs *ofs, - struct dentry *dentry, const char *name) + struct dentry *dentry, const char *name, + bool is_lower) { struct dentry *next = dentry, *parent; int err = 0; @@ -1537,7 +1538,7 @@ static int ovl_check_layer(struct super_ /* Walk back ancestors to root (inclusive) looking for traps */ while (!err && parent != next) { - if (ovl_lookup_trap_inode(sb, parent)) { + if (is_lower && ovl_lookup_trap_inode(sb, parent)) { err = -ELOOP; pr_err("overlayfs: overlapping %s path\n", name); } else if (ovl_is_inuse(parent)) { @@ -1563,7 +1564,7 @@ static int ovl_check_overlapping_layers( if (ofs->upper_mnt) { err = ovl_check_layer(sb, ofs, ofs->upper_mnt->mnt_root, - "upperdir"); + "upperdir", false); if (err) return err; @@ -1574,7 +1575,8 @@ static int ovl_check_overlapping_layers( * workbasedir. In that case, we already have their traps in * inode cache and we will catch that case on lookup. */ - err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir"); + err = ovl_check_layer(sb, ofs, ofs->workbasedir, "workdir", + false); if (err) return err; } @@ -1582,7 +1584,7 @@ static int ovl_check_overlapping_layers( for (i = 0; i < ofs->numlower; i++) { err = ovl_check_layer(sb, ofs, ofs->lower_layers[i].mnt->mnt_root, - "lowerdir"); + "lowerdir", true); if (err) return err; }