From patchwork Mon Jul 26 10:28:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 12399067 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=-19.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 6BD4DC4338F for ; Mon, 26 Jul 2021 10:29:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4F94860F6E for ; Mon, 26 Jul 2021 10:29:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232877AbhGZJsw (ORCPT ); Mon, 26 Jul 2021 05:48:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:35638 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232702AbhGZJsu (ORCPT ); Mon, 26 Jul 2021 05:48:50 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 031C160F6B; Mon, 26 Jul 2021 10:29:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627295359; bh=GsGtyy96wqnROlp2/bZoRye9OVCjTkpIpqpGkIk4cCE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lViMR8Ay2QRlxKnznOClQ7bQllNwz46EXJVEvfVWkXvCpYY/AmndSMCbatAn2e0rF 3pfg4g6uRqjUZY6KXFYc9btb1g/ZrKWGgTBT6wIWUBiQNwnnGHsPqOiYlvVWh8gt4K brr0gsNDDAVdc27qqRMvDV5FzyRzEATCt08xbzzV/RnjEYF1LcOURGVwIgAmmTt6UX 0YdiOE1m1px18umYXyMkq+uyunHO/VE4aLAwO8SydeNh1ITjCHV3xjo1QvS3YMhZjT pgi0Xa+1gdEqDqHCiZOgMAR+cwyYd9T+V4fPmC8olX1K/j6FA/iqUy4V59akms53Cx Ahc1FYJKj6PEw== From: Christian Brauner To: Christoph Hellwig , Chris Mason , Josef Bacik , David Sterba Cc: Al Viro , linux-btrfs@vger.kernel.org, Christian Brauner , Christoph Hellwig Subject: [PATCH v3 12/21] btrfs/ioctl: check whether fs{g,u}id are mapped during subvolume creation Date: Mon, 26 Jul 2021 12:28:07 +0200 Message-Id: <20210726102816.612434-13-brauner@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210726102816.612434-1-brauner@kernel.org> References: <20210726102816.612434-1-brauner@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1711; h=from:subject; bh=xz/8Sa8HC1Rq1Hy4H8Ifh+XNuNCa36O1jKpi/ZdNlmk=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMST86zOxTl9VopScblv1LGIZX1ykwFKuj6HbItgZLh00/2l+ 4dejjlIWBjEuBlkxRRaHdpNwueU8FZuNMjVg5rAygQxh4OIUgInsWcPI8EB3ipxIw9YQ36+JBvc3Cj zfxWbm/o/vyAGOSpcjfztjnRgZFv+Z8+hA2oKHqx5wSKQnN30XLT4Ved+zvVwu5fCXur9FnAA= X-Developer-Key: i=christian.brauner@ubuntu.com; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Christian Brauner When a new subvolume is created btrfs currently doesn't check whether the fs{g,u}id of the caller actually have a mapping in the user namespace attached to the filesystem. The vfs always checks this to make sure that the caller's fs{g,u}id can be represented on-disk. This is most relevant for filesystems that can be mounted inside user namespaces but it is in general a good hardening measure to prevent unrepresentable {g,u}ids from being written to disk. Since we want to support idmapped mounts for btrfs ioctls to create subvolumes in follow-up patches this becomes important since we want to make sure the fs{g,u}id of the caller as mapped according to the idmapped mount can be represented on-disk. Simply add the missing fsuidgid_has_mapping() line from the vfs may_create() version to btrfs_may_create(). Cc: Chris Mason Cc: Josef Bacik Cc: Christoph Hellwig Cc: David Sterba Cc: linux-btrfs@vger.kernel.org Reviewed-by: Josef Bacik Signed-off-by: Christian Brauner --- /* v2 */ unchanged /* v3 */ unchanged --- fs/btrfs/ioctl.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 0ba98e08a029..7a6a886df7c4 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -870,6 +870,8 @@ static inline int btrfs_may_create(struct inode *dir, struct dentry *child) return -EEXIST; if (IS_DEADDIR(dir)) return -ENOENT; + if (!fsuidgid_has_mapping(dir->i_sb, &init_user_ns)) + return -EOVERFLOW; return inode_permission(&init_user_ns, dir, MAY_WRITE | MAY_EXEC); }