From patchwork Tue Nov 23 11:42:18 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 12633979 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 6E754C433FE for ; Tue, 23 Nov 2021 11:42:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236366AbhKWLqC (ORCPT ); Tue, 23 Nov 2021 06:46:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:37340 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231150AbhKWLp5 (ORCPT ); Tue, 23 Nov 2021 06:45:57 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 17006604D1; Tue, 23 Nov 2021 11:42:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1637667769; bh=eDYWLoacrIiYU+DdVUwtlDVC1t/o0I9tt0WGcSZinJA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AggQMmn3srzih7d4BG4PUT69n4A5wdKlN/ltNksuX2nNk2MziKYXWfRyHEmpP2hxX JyOuYmJHU+xGOnH0A2a/7IVhhJNHYvOa9O9pyqF23SXX8VcxhF5zdVYP4ORLjzoed0 T1Y5e5jxCGSAFKi8WsvTV/TlVOrCgxOjgW5z2Qp5Wpiy9sopfQhDmciVSlcRPhlrM5 b5EfO0nIN/moOq+YkgCC/k9M+9299fW4JZiewRdaenp0n/y3whef63WPDnK0ShkevM ExFvGa3vvkpfMZXGw3j1eT9HTFBwJv1JjhizBaZmyrhI5zSiVp+d1HUBrnXkw1euhO jlOkob1rVpR2A== From: Christian Brauner To: Christoph Hellwig Cc: Seth Forshee , Al Viro , linux-fsdevel@vger.kernel.org, Christian Brauner Subject: [PATCH 01/10] fs: add is_mapped_mnt() helper Date: Tue, 23 Nov 2021 12:42:18 +0100 Message-Id: <20211123114227.3124056-2-brauner@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20211123114227.3124056-1-brauner@kernel.org> References: <20211123114227.3124056-1-brauner@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4527; h=from:subject; bh=E6Fhc1ZBU9zBbB0af/1Zb4tZRcDPCL1SiNwHEUX+rVo=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMSTOuVx8QEho5tLtx/+bqOp2PZy9t6q922nXNqPOH9Fbkrgj kwzrOkpZGMS4GGTFFFkc2k3C5ZbzVGw2ytSAmcPKBDKEgYtTACaieJiR4fXP9REeDPWTL7/l1y6Zsn fKu8QbV0KPBr182sLLvfnUeTWG/0E/ox5k7vjGHCji+E5OmKdRdlH5sZYXTjs5PdPS7N9bMwMA X-Developer-Key: i=christian.brauner@ubuntu.com; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Christian Brauner Multiple places open-code the same check to determine whether a given mount is idmapped. Introduce a simple helper function that can be used instead. This allows us to get rid of the fragile open-coding. We will later change the check that is used to determine whether a given mount is idmapped. Introducing a helper allows us to do this in a single place instead of doing it for multiple places. Cc: Seth Forshee Cc: Christoph Hellwig Cc: Al Viro CC: linux-fsdevel@vger.kernel.org Signed-off-by: Christian Brauner --- fs/cachefiles/bind.c | 2 +- fs/ecryptfs/main.c | 2 +- fs/namespace.c | 2 +- fs/nfsd/export.c | 2 +- fs/overlayfs/super.c | 2 +- fs/proc_namespace.c | 2 +- include/linux/fs.h | 14 ++++++++++++++ 7 files changed, 20 insertions(+), 6 deletions(-) diff --git a/fs/cachefiles/bind.c b/fs/cachefiles/bind.c index d463d89f5db8..8130142d89c2 100644 --- a/fs/cachefiles/bind.c +++ b/fs/cachefiles/bind.c @@ -117,7 +117,7 @@ static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache) root = path.dentry; ret = -EINVAL; - if (mnt_user_ns(path.mnt) != &init_user_ns) { + if (is_mapped_mnt(path.mnt)) { pr_warn("File cache on idmapped mounts not supported"); goto error_unsupported; } diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c index d66bbd2df191..331ac3a59515 100644 --- a/fs/ecryptfs/main.c +++ b/fs/ecryptfs/main.c @@ -537,7 +537,7 @@ static struct dentry *ecryptfs_mount(struct file_system_type *fs_type, int flags goto out_free; } - if (mnt_user_ns(path.mnt) != &init_user_ns) { + if (is_mapped_mnt(path.mnt)) { rc = -EINVAL; printk(KERN_ERR "Mounting on idmapped mounts currently disallowed\n"); goto out_free; diff --git a/fs/namespace.c b/fs/namespace.c index 659a8f39c61a..7d7b80b375a4 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3936,7 +3936,7 @@ static int can_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt) * mapping. It makes things simpler and callers can just create * another bind-mount they can idmap if they want to. */ - if (mnt_user_ns(m) != &init_user_ns) + if (is_mapped_mnt(m)) return -EPERM; /* The underlying filesystem doesn't support idmapped mounts yet. */ diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c index 9421dae22737..292bde9e1eb3 100644 --- a/fs/nfsd/export.c +++ b/fs/nfsd/export.c @@ -427,7 +427,7 @@ static int check_export(struct path *path, int *flags, unsigned char *uuid) return -EINVAL; } - if (mnt_user_ns(path->mnt) != &init_user_ns) { + if (is_mapped_mnt(path->mnt)) { dprintk("exp_export: export of idmapped mounts not yet supported.\n"); return -EINVAL; } diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 265181c110ae..113575fc6155 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -873,7 +873,7 @@ static int ovl_mount_dir_noesc(const char *name, struct path *path) pr_err("filesystem on '%s' not supported\n", name); goto out_put; } - if (mnt_user_ns(path->mnt) != &init_user_ns) { + if (is_mapped_mnt(path->mnt)) { pr_err("idmapped layers are currently not supported\n"); goto out_put; } diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c index 392ef5162655..788c687bb052 100644 --- a/fs/proc_namespace.c +++ b/fs/proc_namespace.c @@ -80,7 +80,7 @@ static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt) seq_puts(m, fs_infop->str); } - if (mnt_user_ns(mnt) != &init_user_ns) + if (is_mapped_mnt(mnt)) seq_puts(m, ",idmapped"); } diff --git a/include/linux/fs.h b/include/linux/fs.h index 1cb616fc1105..192242476b2b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2725,6 +2725,20 @@ static inline struct user_namespace *file_mnt_user_ns(struct file *file) { return mnt_user_ns(file->f_path.mnt); } + +/** + * is_mapped_mnt - check whether a mount is mapped + * @mnt: the mount to check + * + * If @mnt has an idmapping attached to it @mnt is mapped. + * + * Return: true if mount is mapped, false if not. + */ +static inline bool is_mapped_mnt(const struct vfsmount *mnt) +{ + return mnt_user_ns(mnt) != &init_user_ns; +} + extern long vfs_truncate(const struct path *, loff_t); int do_truncate(struct user_namespace *, struct dentry *, loff_t start, unsigned int time_attrs, struct file *filp);