From patchwork Fri Dec 3 11:16:58 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 12654869 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 0B5E4C433EF for ; Fri, 3 Dec 2021 11:17:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351729AbhLCLUz (ORCPT ); Fri, 3 Dec 2021 06:20:55 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37168 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243029AbhLCLUy (ORCPT ); Fri, 3 Dec 2021 06:20:54 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B9F69C06173E for ; Fri, 3 Dec 2021 03:17:30 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 5DD66629FD for ; Fri, 3 Dec 2021 11:17:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BD1F3C53FAD; Fri, 3 Dec 2021 11:17:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1638530249; bh=meviJb8hgwYGNH4SRkhqqKuX2soxib9fYnsSaVkhXiw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CdGQPmb4fgULsppbsj75aU9EOUhnbPnI3RLI9DydJWcr6GZXD09mLnzDymxPzzrNY BqraS/ylAgi+g1ejD7FUifzl0JdG8uex7hoqbvpoMBCTxd/06WjVGh3MkcA2UHdzCu rzneOnu3wE3i5CnyrZi0cSgYBJWcKmOMTISCMg3cD7ByvUJyCs+s6PyqEL10/NvLqi Fb29RnoC/hdV8lJQPONGuiOPuZLKUmS3iodYfCH1nUUqrtbwwI0nP1skGvgRdAFFN9 AIT4sMk2HdWx/9eE1rkjnjBcLfYoojcJZxEZcxF3/iPzRrQQedV+OaXSWmRbTPLvVV tD5bNEyMjdjQw== From: Christian Brauner To: Seth Forshee , Christoph Hellwig Cc: Amir Goldstein , Al Viro , linux-fsdevel@vger.kernel.org, Christian Brauner Subject: [PATCH v3 01/10] fs: add is_idmapped_mnt() helper Date: Fri, 3 Dec 2021 12:16:58 +0100 Message-Id: <20211203111707.3901969-2-brauner@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20211203111707.3901969-1-brauner@kernel.org> References: <20211203111707.3901969-1-brauner@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=4929; h=from:subject; bh=4kwr7RdvzDcbx0ni4d6K+hIcw5hbO1odocjGtlQcqPc=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMSSu/DP1T63Jte9T+Z/2XW8IvcY6X41vVmjW08BQs99brO8u mT2Lv6OUhUGMi0FWTJHFod0kXG45T8Vmo0wNmDmsTCBDGLg4BWAi5ycwMtw+epZvscMV6dB/N/+rhu ZNffNa89RpVYPb0ybv6Mhf0JzNyLDK/A/79+gPLUvOeD0s+aT45oRayPeurw4qy/kquJwKn7MCAA== 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. Link: https://lore.kernel.org/r/20211123114227.3124056-2-brauner@kernel.org (v1) Link: https://lore.kernel.org/r/20211130121032.3753852-2-brauner@kernel.org (v2) Cc: Seth Forshee Cc: Christoph Hellwig Cc: Al Viro CC: linux-fsdevel@vger.kernel.org Reviewed-by: Amir Goldstein Reviewed-by: Seth Forshee Signed-off-by: Christian Brauner --- /* v2 */ - Amir Goldstein : - s/is_mapped_mnt/is_idmapped_mnt/g /* v3 */ unchanged --- 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..146291be6263 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_idmapped_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..2dd23a82e0de 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_idmapped_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..4994b816a74c 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_idmapped_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..668c7527b17e 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_idmapped_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..7bb0a47cb615 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_idmapped_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..49650e54d2f8 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_idmapped_mnt(mnt)) seq_puts(m, ",idmapped"); } diff --git a/include/linux/fs.h b/include/linux/fs.h index bbf812ce89a8..06cbefd76de7 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2724,6 +2724,20 @@ static inline struct user_namespace *file_mnt_user_ns(struct file *file) { return mnt_user_ns(file->f_path.mnt); } + +/** + * is_idmapped_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_idmapped_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);