Merge tag 'fs.idmapped.v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping

Pull vfs idmapping updates from Christian Brauner:

 - Last cycle we introduced the dedicated struct mnt_idmap type for
   mount idmapping and the required infrastucture in 256c8aed2b42 ("fs:
   introduce dedicated idmap type for mounts"). As promised in last
   cycle's pull request message this converts everything to rely on
   struct mnt_idmap.

   Currently we still pass around the plain namespace that was attached
   to a mount. This is in general pretty convenient but it makes it easy
   to conflate namespaces that are relevant on the filesystem with
   namespaces that are relevant on the mount level. Especially for
   non-vfs developers without detailed knowledge in this area this was a
   potential source for bugs.

   This finishes the conversion. Instead of passing the plain namespace
   around this updates all places that currently take a pointer to a
   mnt_userns with a pointer to struct mnt_idmap.

   Now that the conversion is done all helpers down to the really
   low-level helpers only accept a struct mnt_idmap argument instead of
   two namespace arguments.

   Conflating mount and other idmappings will now cause the compiler to
   complain loudly thus eliminating the possibility of any bugs. This
   makes it impossible for filesystem developers to mix up mount and
   filesystem idmappings as they are two distinct types and require
   distinct helpers that cannot be used interchangeably.

   Everything associated with struct mnt_idmap is moved into a single
   separate file. With that change no code can poke around in struct
   mnt_idmap. It can only be interacted with through dedicated helpers.
   That means all filesystems are and all of the vfs is completely
   oblivious to the actual implementation of idmappings.

   We are now also able to extend struct mnt_idmap as we see fit. For
   example, we can decouple it completely from namespaces for users that
   don't require or don't want to use them at all. We can also extend
   the concept of idmappings so we can cover filesystem specific
   requirements.

   In combination with the vfs{g,u}id_t work we finished in v6.2 this
   makes this feature substantially more robust and thus difficult to
   implement wrong by a given filesystem and also protects the vfs.

 - Enable idmapped mounts for tmpfs and fulfill a longstanding request.

   A long-standing request from users had been to make it possible to
   create idmapped mounts for tmpfs. For example, to share the host's
   tmpfs mount between multiple sandboxes. This is a prerequisite for
   some advanced Kubernetes cases. Systemd also has a range of use-cases
   to increase service isolation. And there are more users of this.

   However, with all of the other work going on this was way down on the
   priority list but luckily someone other than ourselves picked this
   up.

   As usual the patch is tiny as all the infrastructure work had been
   done multiple kernel releases ago. In addition to all the tests that
   we already have I requested that Rodrigo add a dedicated tmpfs
   testsuite for idmapped mounts to xfstests. It is to be included into
   xfstests during the v6.3 development cycle. This should add a slew of
   additional tests.

* tag 'fs.idmapped.v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping: (26 commits)
  shmem: support idmapped mounts for tmpfs
  fs: move mnt_idmap
  fs: port vfs{g,u}id helpers to mnt_idmap
  fs: port fs{g,u}id helpers to mnt_idmap
  fs: port i_{g,u}id_into_vfs{g,u}id() to mnt_idmap
  fs: port i_{g,u}id_{needs_}update() to mnt_idmap
  quota: port to mnt_idmap
  fs: port privilege checking helpers to mnt_idmap
  fs: port inode_owner_or_capable() to mnt_idmap
  fs: port inode_init_owner() to mnt_idmap
  fs: port acl to mnt_idmap
  fs: port xattr to mnt_idmap
  fs: port ->permission() to pass mnt_idmap
  fs: port ->fileattr_set() to pass mnt_idmap
  fs: port ->set_acl() to pass mnt_idmap
  fs: port ->get_acl() to pass mnt_idmap
  fs: port ->tmpfile() to pass mnt_idmap
  fs: port ->rename() to pass mnt_idmap
  fs: port ->mknod() to pass mnt_idmap
  fs: port ->mkdir() to pass mnt_idmap
  ...

5 files changed, 17 insertions, 17 deletions

diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index b7c1f8c84b38..82690d1dd49a 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -28,17 +28,17 @@ static bool afs_lookup_one_filldir(struct dir_context *ctx, const char *name, in
 				  loff_t fpos, u64 ino, unsigned dtype);
 static bool afs_lookup_filldir(struct dir_context *ctx, const char *name, int nlen,
 			      loff_t fpos, u64 ino, unsigned dtype);
-static int afs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int afs_create(struct mnt_idmap *idmap, struct inode *dir,
 		      struct dentry *dentry, umode_t mode, bool excl);
-static int afs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+static int afs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 		     struct dentry *dentry, umode_t mode);
 static int afs_rmdir(struct inode *dir, struct dentry *dentry);
 static int afs_unlink(struct inode *dir, struct dentry *dentry);
 static int afs_link(struct dentry *from, struct inode *dir,
 		    struct dentry *dentry);
-static int afs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+static int afs_symlink(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *dentry, const char *content);
-static int afs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
+static int afs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
 		      struct dentry *old_dentry, struct inode *new_dir,
 		      struct dentry *new_dentry, unsigned int flags);
 static bool afs_dir_release_folio(struct folio *folio, gfp_t gfp_flags);
@@ -1332,7 +1332,7 @@ static const struct afs_operation_ops afs_mkdir_operation = {
 /*
  * create a directory on an AFS filesystem
  */
-static int afs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+static int afs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 		     struct dentry *dentry, umode_t mode)
 {
 	struct afs_operation *op;
@@ -1630,7 +1630,7 @@ static const struct afs_operation_ops afs_create_operation = {
 /*
  * create a regular file on an AFS filesystem
  */
-static int afs_create(struct user_namespace *mnt_userns, struct inode *dir,
+static int afs_create(struct mnt_idmap *idmap, struct inode *dir,
 		      struct dentry *dentry, umode_t mode, bool excl)
 {
 	struct afs_operation *op;
@@ -1760,7 +1760,7 @@ static const struct afs_operation_ops afs_symlink_operation = {
 /*
  * create a symlink in an AFS filesystem
  */
-static int afs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
+static int afs_symlink(struct mnt_idmap *idmap, struct inode *dir,
 		       struct dentry *dentry, const char *content)
 {
 	struct afs_operation *op;
@@ -1897,7 +1897,7 @@ static const struct afs_operation_ops afs_rename_operation = {
 /*
  * rename a file in an AFS filesystem and/or move it between directories
  */
-static int afs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
+static int afs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
 		      struct dentry *old_dentry, struct inode *new_dir,
 		      struct dentry *new_dentry, unsigned int flags)
 {
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 6d3a3dbe4928..0167e96e5198 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -737,7 +737,7 @@ error_unlock:
 /*
  * read the attributes of an inode
  */
-int afs_getattr(struct user_namespace *mnt_userns, const struct path *path,
+int afs_getattr(struct mnt_idmap *idmap, const struct path *path,
 		struct kstat *stat, u32 request_mask, unsigned int query_flags)
 {
 	struct inode *inode = d_inode(path->dentry);
@@ -761,7 +761,7 @@ int afs_getattr(struct user_namespace *mnt_userns, const struct path *path,
 
 	do {
 		read_seqbegin_or_lock(&vnode->cb_lock, &seq);
-		generic_fillattr(&init_user_ns, inode, stat);
+		generic_fillattr(&nop_mnt_idmap, inode, stat);
 		if (test_bit(AFS_VNODE_SILLY_DELETED, &vnode->flags) &&
 		    stat->nlink > 0)
 			stat->nlink -= 1;
@@ -870,7 +870,7 @@ static const struct afs_operation_ops afs_setattr_operation = {
 /*
  * set the attributes of an inode
  */
-int afs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+int afs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		struct iattr *attr)
 {
 	const unsigned int supported =
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 2d6d7dae225a..ad8523d0d038 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -1171,9 +1171,9 @@ extern struct inode *afs_iget(struct afs_operation *, struct afs_vnode_param *);
 extern struct inode *afs_root_iget(struct super_block *, struct key *);
 extern bool afs_check_validity(struct afs_vnode *);
 extern int afs_validate(struct afs_vnode *, struct key *);
-extern int afs_getattr(struct user_namespace *mnt_userns, const struct path *,
+extern int afs_getattr(struct mnt_idmap *idmap, const struct path *,
 		       struct kstat *, u32, unsigned int);
-extern int afs_setattr(struct user_namespace *mnt_userns, struct dentry *, struct iattr *);
+extern int afs_setattr(struct mnt_idmap *idmap, struct dentry *, struct iattr *);
 extern void afs_evict_inode(struct inode *);
 extern int afs_drop_inode(struct inode *);
 
@@ -1388,7 +1388,7 @@ extern void afs_cache_permit(struct afs_vnode *, struct key *, unsigned int,
 extern struct key *afs_request_key(struct afs_cell *);
 extern struct key *afs_request_key_rcu(struct afs_cell *);
 extern int afs_check_permit(struct afs_vnode *, struct key *, afs_access_t *);
-extern int afs_permission(struct user_namespace *, struct inode *, int);
+extern int afs_permission(struct mnt_idmap *, struct inode *, int);
 extern void __exit afs_clean_up_permit_cache(void);
 
 /*
diff --git a/fs/afs/security.c b/fs/afs/security.c
index 7c6a63a30394..6a7744c9e2a2 100644
--- a/fs/afs/security.c
+++ b/fs/afs/security.c
@@ -395,7 +395,7 @@ int afs_check_permit(struct afs_vnode *vnode, struct key *key,
  * - AFS ACLs are attached to directories only, and a file is controlled by its
  *   parent directory's ACL
  */
-int afs_permission(struct user_namespace *mnt_userns, struct inode *inode,
+int afs_permission(struct mnt_idmap *idmap, struct inode *inode,
 		   int mask)
 {
 	struct afs_vnode *vnode = AFS_FS_I(inode);
diff --git a/fs/afs/xattr.c b/fs/afs/xattr.c
index 7751b0b3f81d..9048d8ccc715 100644
--- a/fs/afs/xattr.c
+++ b/fs/afs/xattr.c
@@ -97,7 +97,7 @@ static const struct afs_operation_ops afs_store_acl_operation = {
  * Set a file's AFS3 ACL.
  */
 static int afs_xattr_set_acl(const struct xattr_handler *handler,
-			     struct user_namespace *mnt_userns,
+			     struct mnt_idmap *idmap,
                              struct dentry *dentry,
                              struct inode *inode, const char *name,
                              const void *buffer, size_t size, int flags)
@@ -228,7 +228,7 @@ static const struct afs_operation_ops yfs_store_opaque_acl2_operation = {
  * Set a file's YFS ACL.
  */
 static int afs_xattr_set_yfs(const struct xattr_handler *handler,
-			     struct user_namespace *mnt_userns,
+			     struct mnt_idmap *idmap,
                              struct dentry *dentry,
                              struct inode *inode, const char *name,
                              const void *buffer, size_t size, int flags)