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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 45E88C54EED for ; Mon, 30 Jan 2023 14:18:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237481AbjA3OSR (ORCPT ); Mon, 30 Jan 2023 09:18:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33342 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237417AbjA3ORp (ORCPT ); Mon, 30 Jan 2023 09:17:45 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF01C3D91D for ; Mon, 30 Jan 2023 06:17:14 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id B81E8B8117E for ; Mon, 30 Jan 2023 14:17:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0D442C433EF; Mon, 30 Jan 2023 14:17:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1675088231; bh=NpE4qk2r3b6JEYuQ0FQRJxbacoXtu3zARHZ14KdC/Bk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mlJ1rHl3dDOk9XjJPYCXqxjPfPwZsqs6OG65M+grUCy28yiFE1qAcngMfBtMiGhr6 RbIvJLAfkVeA4wUjVDmtfiIc6/xeRM5RfcisDpr43McFADxc2xPltkETuGnKes1Hv2 gZvWfNjUENylOkm/yanNOdon3tk+Qq4MtwI/Yo50= 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 5.15 159/204] ovl: fail on invalid uid/gid mapping at copy up Date: Mon, 30 Jan 2023 14:52:04 +0100 Message-Id: <20230130134323.540562837@linuxfoundation.org> X-Mailer: git-send-email 2.39.1 In-Reply-To: <20230130134316.327556078@linuxfoundation.org> References: <20230130134316.327556078@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 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 @@ -960,6 +960,10 @@ 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) {