fs: port ->set_acl() to pass mnt_idmap

Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to 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 relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>

1 files changed, 21 insertions, 18 deletions

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 17e141a94671..678b86ec2b4c 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -591,18 +591,18 @@ EXPORT_SYMBOL(__posix_acl_chmod);
 /**
  * posix_acl_chmod - chmod a posix acl
  *
- * @mnt_userns:	user namespace of the mount @inode was found from
+ * @idmap:	idmap of the mount @inode was found from
  * @dentry:	dentry to check permissions on
  * @mode:	the new mode of @inode
  *
- * If the dentry has been found through an idmapped mount the user namespace of
- * the vfsmount must be passed through @mnt_userns. This function will then
- * take care to map the inode according to @mnt_userns before checking
+ * If the dentry has been found through an idmapped mount the idmap of
+ * the vfsmount must be passed through @idmap. This function will then
+ * take care to map the inode according to @idmap before checking
  * permissions. On non-idmapped mounts or if permission checking is to be
- * performed on the raw inode simply passs init_user_ns.
+ * performed on the raw inode simply passs @nop_mnt_idmap.
  */
 int
- posix_acl_chmod(struct user_namespace *mnt_userns, struct dentry *dentry,
+ posix_acl_chmod(struct mnt_idmap *idmap, struct dentry *dentry,
 		    umode_t mode)
 {
 	struct inode *inode = d_inode(dentry);
@@ -624,7 +624,7 @@ int
 	ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
 	if (ret)
 		return ret;
-	ret = inode->i_op->set_acl(mnt_userns, dentry, acl, ACL_TYPE_ACCESS);
+	ret = inode->i_op->set_acl(idmap, dentry, acl, ACL_TYPE_ACCESS);
 	posix_acl_release(acl);
 	return ret;
 }
@@ -934,7 +934,7 @@ static ssize_t vfs_posix_acl_to_xattr(struct mnt_idmap *idmap,
 }
 
 int
-set_posix_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
+set_posix_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 	      int type, struct posix_acl *acl)
 {
 	struct inode *inode = d_inode(dentry);
@@ -946,7 +946,7 @@ set_posix_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
 
 	if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 		return acl ? -EACCES : 0;
-	if (!inode_owner_or_capable(mnt_userns, inode))
+	if (!inode_owner_or_capable(mnt_idmap_owner(idmap), inode))
 		return -EPERM;
 
 	if (acl) {
@@ -954,7 +954,7 @@ set_posix_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
 		if (ret)
 			return ret;
 	}
-	return inode->i_op->set_acl(mnt_userns, dentry, acl, type);
+	return inode->i_op->set_acl(idmap, dentry, acl, type);
 }
 EXPORT_SYMBOL(set_posix_acl);
 
@@ -978,10 +978,11 @@ const struct xattr_handler posix_acl_default_xattr_handler = {
 };
 EXPORT_SYMBOL_GPL(posix_acl_default_xattr_handler);
 
-int simple_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
+int simple_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		   struct posix_acl *acl, int type)
 {
 	int error;
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	struct inode *inode = d_inode(dentry);
 
 	if (type == ACL_TYPE_ACCESS) {
@@ -1041,7 +1042,7 @@ static int vfs_set_acl_idmapped_mnt(struct user_namespace *mnt_userns,
 
 /**
  * vfs_set_acl - set posix acls
- * @mnt_userns: user namespace of the mount
+ * @idmap: idmap of the mount
  * @dentry: the dentry based on which to set the posix acls
  * @acl_name: the name of the posix acl
  * @kacl: the posix acls in the appropriate VFS format
@@ -1051,11 +1052,12 @@ static int vfs_set_acl_idmapped_mnt(struct user_namespace *mnt_userns,
  *
  * Return: On success 0, on error negative errno.
  */
-int vfs_set_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
+int vfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		const char *acl_name, struct posix_acl *kacl)
 {
 	int acl_type;
 	int error;
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	struct inode *inode = d_inode(dentry);
 	struct inode *delegated_inode = NULL;
 
@@ -1096,7 +1098,7 @@ retry_deleg:
 		goto out_inode_unlock;
 
 	if (inode->i_opflags & IOP_XATTR)
-		error = set_posix_acl(mnt_userns, dentry, acl_type, kacl);
+		error = set_posix_acl(idmap, dentry, acl_type, kacl);
 	else if (unlikely(is_bad_inode(inode)))
 		error = -EIO;
 	else
@@ -1167,7 +1169,7 @@ EXPORT_SYMBOL_GPL(vfs_get_acl);
 
 /**
  * vfs_remove_acl - remove posix acls
- * @mnt_userns: user namespace of the mount
+ * @idmap: idmap of the mount
  * @dentry: the dentry based on which to retrieve the posix acls
  * @acl_name: the name of the posix acl
  *
@@ -1175,11 +1177,12 @@ EXPORT_SYMBOL_GPL(vfs_get_acl);
  *
  * Return: On success 0, on error negative errno.
  */
-int vfs_remove_acl(struct user_namespace *mnt_userns, struct dentry *dentry,
+int vfs_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		   const char *acl_name)
 {
 	int acl_type;
 	int error;
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	struct inode *inode = d_inode(dentry);
 	struct inode *delegated_inode = NULL;
 
@@ -1207,7 +1210,7 @@ retry_deleg:
 		goto out_inode_unlock;
 
 	if (inode->i_opflags & IOP_XATTR)
-		error = set_posix_acl(mnt_userns, dentry, acl_type, NULL);
+		error = set_posix_acl(idmap, dentry, acl_type, NULL);
 	else if (unlikely(is_bad_inode(inode)))
 		error = -EIO;
 	else
@@ -1246,7 +1249,7 @@ int do_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 			return PTR_ERR(acl);
 	}
 
-	error = vfs_set_acl(mnt_idmap_owner(idmap), dentry, acl_name, acl);
+	error = vfs_set_acl(idmap, dentry, acl_name, acl);
 	posix_acl_release(acl);
 	return error;
 }