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 31B53C433EF for ; Tue, 30 Nov 2021 08:48:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239819AbhK3Ivj (ORCPT ); Tue, 30 Nov 2021 03:51:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60166 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232024AbhK3Ive (ORCPT ); Tue, 30 Nov 2021 03:51:34 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6DB48C061574 for ; Tue, 30 Nov 2021 00:48:15 -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 sin.source.kernel.org (Postfix) with ESMTPS id B9C6FCE181F for ; Tue, 30 Nov 2021 08:48:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7FE5DC53FC1; Tue, 30 Nov 2021 08:48:10 +0000 (UTC) Date: Tue, 30 Nov 2021 09:48:07 +0100 From: Christian Brauner To: Amir Goldstein Cc: Christian Brauner , Christoph Hellwig , Seth Forshee , Al Viro , linux-fsdevel Subject: Re: [PATCH 01/10] fs: add is_mapped_mnt() helper Message-ID: <20211130084807.jebnzt37b5ourva4@wittgenstein> References: <20211123114227.3124056-1-brauner@kernel.org> <20211123114227.3124056-2-brauner@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Nov 30, 2021 at 08:25:40AM +0200, Amir Goldstein wrote: > On Tue, Nov 23, 2021 at 2:18 PM Christian Brauner wrote: > > > > 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; > > +} > > + > > Maybe is_idmapped_mnt? Fine by me!