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
  ...

1 files changed, 41 insertions, 42 deletions

diff --git a/fs/xattr.c b/fs/xattr.c
index 3fead374901b..14a7eb3c8fa8 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -83,7 +83,7 @@ xattr_resolve_name(struct inode *inode, const char **name)
 
 /**
  * may_write_xattr - check whether inode allows writing xattr
- * @mnt_userns:	User namespace of the mount the inode was found from
+ * @idmap: idmap of the mount the inode was found from
  * @inode: the inode on which to set an xattr
  *
  * Check whether the inode allows writing xattrs. Specifically, we can never
@@ -95,13 +95,13 @@ xattr_resolve_name(struct inode *inode, const char **name)
  *
  * Return: On success zero is returned. On error a negative errno is returned.
  */
-int may_write_xattr(struct user_namespace *mnt_userns, struct inode *inode)
+int may_write_xattr(struct mnt_idmap *idmap, struct inode *inode)
 {
 	if (IS_IMMUTABLE(inode))
 		return -EPERM;
 	if (IS_APPEND(inode))
 		return -EPERM;
-	if (HAS_UNMAPPED_ID(mnt_userns, inode))
+	if (HAS_UNMAPPED_ID(idmap, inode))
 		return -EPERM;
 	return 0;
 }
@@ -111,13 +111,13 @@ int may_write_xattr(struct user_namespace *mnt_userns, struct inode *inode)
  * because different namespaces have very different rules.
  */
 static int
-xattr_permission(struct user_namespace *mnt_userns, struct inode *inode,
+xattr_permission(struct mnt_idmap *idmap, struct inode *inode,
 		 const char *name, int mask)
 {
 	if (mask & MAY_WRITE) {
 		int ret;
 
-		ret = may_write_xattr(mnt_userns, inode);
+		ret = may_write_xattr(idmap, inode);
 		if (ret)
 			return ret;
 	}
@@ -149,11 +149,11 @@ xattr_permission(struct user_namespace *mnt_userns, struct inode *inode,
 			return (mask & MAY_WRITE) ? -EPERM : -ENODATA;
 		if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) &&
 		    (mask & MAY_WRITE) &&
-		    !inode_owner_or_capable(mnt_userns, inode))
+		    !inode_owner_or_capable(idmap, inode))
 			return -EPERM;
 	}
 
-	return inode_permission(mnt_userns, inode, mask);
+	return inode_permission(idmap, inode, mask);
 }
 
 /*
@@ -184,7 +184,7 @@ xattr_supported_namespace(struct inode *inode, const char *prefix)
 EXPORT_SYMBOL(xattr_supported_namespace);
 
 int
-__vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+__vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	       struct inode *inode, const char *name, const void *value,
 	       size_t size, int flags)
 {
@@ -200,7 +200,7 @@ __vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 		return -EOPNOTSUPP;
 	if (size == 0)
 		value = "";  /* empty EA, do not remove */
-	return handler->set(handler, mnt_userns, dentry, inode, name, value,
+	return handler->set(handler, idmap, dentry, inode, name, value,
 			    size, flags);
 }
 EXPORT_SYMBOL(__vfs_setxattr);
@@ -209,7 +209,7 @@ EXPORT_SYMBOL(__vfs_setxattr);
  *  __vfs_setxattr_noperm - perform setxattr operation without performing
  *  permission checks.
  *
- *  @mnt_userns: user namespace of the mount the inode was found from
+ *  @idmap: idmap of the mount the inode was found from
  *  @dentry: object to perform setxattr on
  *  @name: xattr name to set
  *  @value: value to set @name to
@@ -222,7 +222,7 @@ EXPORT_SYMBOL(__vfs_setxattr);
  *  is executed. It also assumes that the caller will make the appropriate
  *  permission checks.
  */
-int __vfs_setxattr_noperm(struct user_namespace *mnt_userns,
+int __vfs_setxattr_noperm(struct mnt_idmap *idmap,
 			  struct dentry *dentry, const char *name,
 			  const void *value, size_t size, int flags)
 {
@@ -234,7 +234,7 @@ int __vfs_setxattr_noperm(struct user_namespace *mnt_userns,
 	if (issec)
 		inode->i_flags &= ~S_NOSEC;
 	if (inode->i_opflags & IOP_XATTR) {
-		error = __vfs_setxattr(mnt_userns, dentry, inode, name, value,
+		error = __vfs_setxattr(idmap, dentry, inode, name, value,
 				       size, flags);
 		if (!error) {
 			fsnotify_xattr(dentry);
@@ -265,7 +265,7 @@ int __vfs_setxattr_noperm(struct user_namespace *mnt_userns,
  * __vfs_setxattr_locked - set an extended attribute while holding the inode
  * lock
  *
- *  @mnt_userns: user namespace of the mount of the target inode
+ *  @idmap: idmap of the mount of the target inode
  *  @dentry: object to perform setxattr on
  *  @name: xattr name to set
  *  @value: value to set @name to
@@ -275,18 +275,18 @@ int __vfs_setxattr_noperm(struct user_namespace *mnt_userns,
  *  a delegation was broken on, NULL if none.
  */
 int
-__vfs_setxattr_locked(struct user_namespace *mnt_userns, struct dentry *dentry,
+__vfs_setxattr_locked(struct mnt_idmap *idmap, struct dentry *dentry,
 		      const char *name, const void *value, size_t size,
 		      int flags, struct inode **delegated_inode)
 {
 	struct inode *inode = dentry->d_inode;
 	int error;
 
-	error = xattr_permission(mnt_userns, inode, name, MAY_WRITE);
+	error = xattr_permission(idmap, inode, name, MAY_WRITE);
 	if (error)
 		return error;
 
-	error = security_inode_setxattr(mnt_userns, dentry, name, value, size,
+	error = security_inode_setxattr(idmap, dentry, name, value, size,
 					flags);
 	if (error)
 		goto out;
@@ -295,7 +295,7 @@ __vfs_setxattr_locked(struct user_namespace *mnt_userns, struct dentry *dentry,
 	if (error)
 		goto out;
 
-	error = __vfs_setxattr_noperm(mnt_userns, dentry, name, value,
+	error = __vfs_setxattr_noperm(idmap, dentry, name, value,
 				      size, flags);
 
 out:
@@ -304,7 +304,7 @@ out:
 EXPORT_SYMBOL_GPL(__vfs_setxattr_locked);
 
 int
-vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	     const char *name, const void *value, size_t size, int flags)
 {
 	struct inode *inode = dentry->d_inode;
@@ -313,7 +313,7 @@ vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 	int error;
 
 	if (size && strcmp(name, XATTR_NAME_CAPS) == 0) {
-		error = cap_convert_nscap(mnt_userns, dentry, &value, size);
+		error = cap_convert_nscap(idmap, dentry, &value, size);
 		if (error < 0)
 			return error;
 		size = error;
@@ -321,7 +321,7 @@ vfs_setxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 
 retry_deleg:
 	inode_lock(inode);
-	error = __vfs_setxattr_locked(mnt_userns, dentry, name, value, size,
+	error = __vfs_setxattr_locked(idmap, dentry, name, value, size,
 				      flags, &delegated_inode);
 	inode_unlock(inode);
 
@@ -338,19 +338,19 @@ retry_deleg:
 EXPORT_SYMBOL_GPL(vfs_setxattr);
 
 static ssize_t
-xattr_getsecurity(struct user_namespace *mnt_userns, struct inode *inode,
+xattr_getsecurity(struct mnt_idmap *idmap, struct inode *inode,
 		  const char *name, void *value, size_t size)
 {
 	void *buffer = NULL;
 	ssize_t len;
 
 	if (!value || !size) {
-		len = security_inode_getsecurity(mnt_userns, inode, name,
+		len = security_inode_getsecurity(idmap, inode, name,
 						 &buffer, false);
 		goto out_noalloc;
 	}
 
-	len = security_inode_getsecurity(mnt_userns, inode, name, &buffer,
+	len = security_inode_getsecurity(idmap, inode, name, &buffer,
 					 true);
 	if (len < 0)
 		return len;
@@ -375,7 +375,7 @@ out_noalloc:
  * Returns the result of alloc, if failed, or the getxattr operation.
  */
 int
-vfs_getxattr_alloc(struct user_namespace *mnt_userns, struct dentry *dentry,
+vfs_getxattr_alloc(struct mnt_idmap *idmap, struct dentry *dentry,
 		   const char *name, char **xattr_value, size_t xattr_size,
 		   gfp_t flags)
 {
@@ -384,7 +384,7 @@ vfs_getxattr_alloc(struct user_namespace *mnt_userns, struct dentry *dentry,
 	char *value = *xattr_value;
 	int error;
 
-	error = xattr_permission(mnt_userns, inode, name, MAY_READ);
+	error = xattr_permission(idmap, inode, name, MAY_READ);
 	if (error)
 		return error;
 
@@ -428,13 +428,13 @@ __vfs_getxattr(struct dentry *dentry, struct inode *inode, const char *name,
 EXPORT_SYMBOL(__vfs_getxattr);
 
 ssize_t
-vfs_getxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+vfs_getxattr(struct mnt_idmap *idmap, struct dentry *dentry,
 	     const char *name, void *value, size_t size)
 {
 	struct inode *inode = dentry->d_inode;
 	int error;
 
-	error = xattr_permission(mnt_userns, inode, name, MAY_READ);
+	error = xattr_permission(idmap, inode, name, MAY_READ);
 	if (error)
 		return error;
 
@@ -445,7 +445,7 @@ vfs_getxattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 	if (!strncmp(name, XATTR_SECURITY_PREFIX,
 				XATTR_SECURITY_PREFIX_LEN)) {
 		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
-		int ret = xattr_getsecurity(mnt_userns, inode, suffix, value,
+		int ret = xattr_getsecurity(idmap, inode, suffix, value,
 					    size);
 		/*
 		 * Only overwrite the return value if a security module
@@ -481,7 +481,7 @@ vfs_listxattr(struct dentry *dentry, char *list, size_t size)
 EXPORT_SYMBOL_GPL(vfs_listxattr);
 
 int
-__vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+__vfs_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		  const char *name)
 {
 	struct inode *inode = d_inode(dentry);
@@ -495,7 +495,7 @@ __vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 		return PTR_ERR(handler);
 	if (!handler->set)
 		return -EOPNOTSUPP;
-	return handler->set(handler, mnt_userns, dentry, inode, name, NULL, 0,
+	return handler->set(handler, idmap, dentry, inode, name, NULL, 0,
 			    XATTR_REPLACE);
 }
 EXPORT_SYMBOL(__vfs_removexattr);
@@ -504,25 +504,25 @@ EXPORT_SYMBOL(__vfs_removexattr);
  * __vfs_removexattr_locked - set an extended attribute while holding the inode
  * lock
  *
- *  @mnt_userns: user namespace of the mount of the target inode
+ *  @idmap: idmap of the mount of the target inode
  *  @dentry: object to perform setxattr on
  *  @name: name of xattr to remove
  *  @delegated_inode: on return, will contain an inode pointer that
  *  a delegation was broken on, NULL if none.
  */
 int
-__vfs_removexattr_locked(struct user_namespace *mnt_userns,
+__vfs_removexattr_locked(struct mnt_idmap *idmap,
 			 struct dentry *dentry, const char *name,
 			 struct inode **delegated_inode)
 {
 	struct inode *inode = dentry->d_inode;
 	int error;
 
-	error = xattr_permission(mnt_userns, inode, name, MAY_WRITE);
+	error = xattr_permission(idmap, inode, name, MAY_WRITE);
 	if (error)
 		return error;
 
-	error = security_inode_removexattr(mnt_userns, dentry, name);
+	error = security_inode_removexattr(idmap, dentry, name);
 	if (error)
 		goto out;
 
@@ -530,7 +530,7 @@ __vfs_removexattr_locked(struct user_namespace *mnt_userns,
 	if (error)
 		goto out;
 
-	error = __vfs_removexattr(mnt_userns, dentry, name);
+	error = __vfs_removexattr(idmap, dentry, name);
 
 	if (!error) {
 		fsnotify_xattr(dentry);
@@ -543,7 +543,7 @@ out:
 EXPORT_SYMBOL_GPL(__vfs_removexattr_locked);
 
 int
-vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry,
+vfs_removexattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		const char *name)
 {
 	struct inode *inode = dentry->d_inode;
@@ -552,7 +552,7 @@ vfs_removexattr(struct user_namespace *mnt_userns, struct dentry *dentry,
 
 retry_deleg:
 	inode_lock(inode);
-	error = __vfs_removexattr_locked(mnt_userns, dentry,
+	error = __vfs_removexattr_locked(idmap, dentry,
 					 name, &delegated_inode);
 	inode_unlock(inode);
 
@@ -606,7 +606,7 @@ int do_setxattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		return do_set_acl(idmap, dentry, ctx->kname->name,
 				  ctx->kvalue, ctx->size);
 
-	return vfs_setxattr(mnt_idmap_owner(idmap), dentry, ctx->kname->name,
+	return vfs_setxattr(idmap, dentry, ctx->kname->name,
 			ctx->kvalue, ctx->size, ctx->flags);
 }
 
@@ -715,8 +715,7 @@ do_getxattr(struct mnt_idmap *idmap, struct dentry *d,
 	if (is_posix_acl_xattr(ctx->kname->name))
 		error = do_get_acl(idmap, d, kname, ctx->kvalue, ctx->size);
 	else
-		error = vfs_getxattr(mnt_idmap_owner(idmap), d, kname,
-				     ctx->kvalue, ctx->size);
+		error = vfs_getxattr(idmap, d, kname, ctx->kvalue, ctx->size);
 	if (error > 0) {
 		if (ctx->size && copy_to_user(ctx->value, ctx->kvalue, error))
 			error = -EFAULT;
@@ -893,9 +892,9 @@ removexattr(struct mnt_idmap *idmap, struct dentry *d,
 		return error;
 
 	if (is_posix_acl_xattr(kname))
-		return vfs_remove_acl(mnt_idmap_owner(idmap), d, kname);
+		return vfs_remove_acl(idmap, d, kname);
 
-	return vfs_removexattr(mnt_idmap_owner(idmap), d, kname);
+	return vfs_removexattr(idmap, d, kname);
 }
 
 static int path_removexattr(const char __user *pathname,