From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8AA8E28EB for ; Mon, 30 Jan 2023 14:04:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D91B3C433EF; Mon, 30 Jan 2023 14:04:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1675087478; bh=zpZSmf0BV5gofhulIRolHvgq1rMETCReuoPPApKAlHw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KfS/0XLLEOT7exDRVzLWVnDbmXcPw1GAD8tkFdZkv1BDHLal25aHfv6L3R3xWS13B nT7tijvKyjSMcsine2VoN+OOpHGeKf1ZrXPWNS24zRGQXBk8kgyVXDQzkNvzbmB5oY 3yk2eopmzdyIVA7c9O+Efz7y8WssurjMeLnUlyVI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Miklos Szeredi , Christian Brauner , Seth Forshee Subject: [PATCH 6.1 221/313] ovl: fail on invalid uid/gid mapping at copy up Date: Mon, 30 Jan 2023 14:50:56 +0100 Message-Id: <20230130134347.008063171@linuxfoundation.org> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230130134336.532886729@linuxfoundation.org> References: <20230130134336.532886729@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Miklos Szeredi commit 4f11ada10d0ad3fd53e2bd67806351de63a4f9c3 upstream. If st_uid/st_gid doesn't have a mapping in the mounter's user_ns, then copy-up should fail, just like it would fail if the mounter task was doing the copy using "cp -a". There's a corner case where the "cp -a" would succeed but copy up fail: if there's a mapping of the invalid uid/gid (65534 by default) in the user namespace. This is because stat(2) will return this value if the mapping doesn't exist in the current user_ns and "cp -a" will in turn be able to create a file with this uid/gid. This behavior would be inconsistent with POSIX ACL's, which return -1 for invalid uid/gid which result in a failed copy. For consistency and simplicity fail the copy of the st_uid/st_gid are invalid. Fixes: 459c7c565ac3 ("ovl: unprivieged mounts") Cc: # v5.11 Signed-off-by: Miklos Szeredi Reviewed-by: Christian Brauner Reviewed-by: Seth Forshee Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/copy_up.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -973,6 +973,10 @@ static int ovl_copy_up_one(struct dentry if (err) return err; + if (!kuid_has_mapping(current_user_ns(), ctx.stat.uid) || + !kgid_has_mapping(current_user_ns(), ctx.stat.gid)) + return -EOVERFLOW; + ctx.metacopy = ovl_need_meta_copy_up(dentry, ctx.stat.mode, flags); if (parent) {