From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx4+ov2IXgJKLlZvwTN20jJ3Lg4huAItMV7/QkEuelbNZH8lEFpxpizvYjAzHsMlqjBu5Z8Fw ARC-Seal: i=1; a=rsa-sha256; t=1523980902; cv=none; d=google.com; s=arc-20160816; b=L6lv+Dkt64kXFHOH5+OpdhtKrU0Q3YVN2PiWffA/2rZ2RdtORs9kmdCq/JJbr4jWo4 4QgxeM//0EBkoeAJKz0u1uXScopOwE00k3DeXrvH7wPjkQkkO/nRiDq7VADe6lfFt/C0 xW0YelkesOtiZTVcOUjpYcwC3wnxxUtrAuogpqu7J/y0aWRpx1fwb1r+hsU2Mb3RRRZG ZpFBIvwbhmW5nV9uZ2GZWR/eqwOYnlAFHOjYNH+pLMCV9AtexJm7huQf5Db34VvlrH+B Uk304kZyvrKa9WfJrftZw1tA3gwZHJm/bY9tcW1pLKgkKpxH87q7RVvy3+FnuHWHfqvh 5SIQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=+MM7OvZ4LgEfhx319mmCmq9BHVcpABUmJbGTQKYfx2Y=; b=A8bNrQMTB21v4OPHAYAb4RVkQWKqjra3eRCIVDEzR/yPDZvQ4tdnK4iEnjTqqAEkBt ZwVArrzsNz8EEm1O6iG9WPYrBPe3iHs/7gPJcb6AWvKha9s8huHbrT+7of3a58b2SdT5 UOGozev7gRZu1QFo62aVV31OUQxpUWiv8lgRlXNmS2EemVqZTgvqBzM0G0Xk3tSqCj+u 6kZtGcVkEyer9azk+RDpuMck9V89O1ngaTGX25QtgI36tR8iIFMJaYsuHnfZIl1+Gn70 WPbPbnKUX6SGzFprVSY3aD0UKoxoXWVK4pgOBtmhXzDzruNLXWkYQ6oR1StSZPULzorD Y1/Q== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 46.44.180.42 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 46.44.180.42 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Amir Goldstein , Vivek Goyal , Miklos Szeredi Subject: [PATCH 4.16 45/68] ovl: fix lookup with middle layer opaque dir and absolute path redirects Date: Tue, 17 Apr 2018 17:57:58 +0200 Message-Id: <20180417155751.169731940@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180417155749.341779147@linuxfoundation.org> References: <20180417155749.341779147@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1598009799059325863?= X-GMAIL-MSGID: =?utf-8?q?1598009799059325863?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Amir Goldstein commit 3ec9b3fafcaf441cc4d46b9742cd6ec0c79f8df0 upstream. As of now if we encounter an opaque dir while looking for a dentry, we set d->last=true. This means that there is no need to look further in any of the lower layers. This works fine as long as there are no redirets or relative redircts. But what if there is an absolute redirect on the children dentry of opaque directory. We still need to continue to look into next lower layer. This patch fixes it. Here is an example to demonstrate the issue. Say you have following setup. upper: /redirect (redirect=/a/b/c) lower1: /a/[b]/c ([b] is opaque) (c has absolute redirect=/a/b/d/) lower0: /a/b/d/foo Now "redirect" dir should merge with lower1:/a/b/c/ and lower0:/a/b/d. Note, despite the fact lower1:/a/[b] is opaque, we need to continue to look into lower0 because children c has an absolute redirect. Following is a reproducer. Watch me make foo disappear: $ mkdir lower middle upper work work2 merged $ mkdir lower/origin $ touch lower/origin/foo $ mount -t overlay none merged/ \ -olowerdir=lower,upperdir=middle,workdir=work2 $ mkdir merged/pure $ mv merged/origin merged/pure/redirect $ umount merged $ mount -t overlay none merged/ \ -olowerdir=middle:lower,upperdir=upper,workdir=work $ mv merged/pure/redirect merged/redirect Now you see foo inside a twice redirected merged dir: $ ls merged/redirect foo $ umount merged $ mount -t overlay none merged/ \ -olowerdir=middle:lower,upperdir=upper,workdir=work After mount cycle you don't see foo inside the same dir: $ ls merged/redirect During middle layer lookup, the opaqueness of middle/pure is left in the lookup state and then middle/pure/redirect is wrongly treated as opaque. Fixes: 02b69b284cd7 ("ovl: lookup redirects") Cc: #v4.10 Signed-off-by: Amir Goldstein Signed-off-by: Vivek Goyal Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/namei.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/fs/overlayfs/namei.c +++ b/fs/overlayfs/namei.c @@ -56,6 +56,15 @@ static int ovl_check_redirect(struct den if (s == next) goto invalid; } + /* + * One of the ancestor path elements in an absolute path + * lookup in ovl_lookup_layer() could have been opaque and + * that will stop further lookup in lower layers (d->stop=true) + * But we have found an absolute redirect in decendant path + * element and that should force continue lookup in lower + * layers (reset d->stop). + */ + d->stop = false; } else { if (strchr(buf, '/') != NULL) goto invalid;