On Tue, Nov 30, 2021 at 01:10:23PM +0100, Christian Brauner wrote: > From: Christian Brauner <christian.brauner@xxxxxxxxxx> > > 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@xxxxxxxxxx (v1) > Cc: Seth Forshee <sforshee@xxxxxxxxxxxxxxxx> > Cc: Amir Goldstein <amir73il@xxxxxxxxx> > Cc: Christoph Hellwig <hch@xxxxxx> > Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > CC: linux-fsdevel@xxxxxxxxxxxxxxx > Signed-off-by: Christian Brauner <christian.brauner@xxxxxxxxxx> Reviewed-by: Seth Forshee <sforshee@xxxxxxxxxxxxxxxx> > --- > /* v2 */ > - Amir Goldstein <amir73il@xxxxxxxxx>: > - s/is_mapped_mnt/is_idmapped_mnt/g > --- > 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 1cb616fc1105..426cc7bcbeb8 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_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); > -- > 2.30.2 >
