fs: port acl to 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, 18 insertions, 18 deletions

diff --git a/fs/posix_acl.c b/fs/posix_acl.c
index 1cd8c01508b8..b6c3b5b19435 100644
--- a/fs/posix_acl.c
+++ b/fs/posix_acl.c
@@ -372,11 +372,12 @@ EXPORT_SYMBOL(posix_acl_from_mode);
  * by the acl. Returns -E... otherwise.
  */
 int
-posix_acl_permission(struct user_namespace *mnt_userns, struct inode *inode,
+posix_acl_permission(struct mnt_idmap *idmap, struct inode *inode,
 		     const struct posix_acl *acl, int want)
 {
 	const struct posix_acl_entry *pa, *pe, *mask_obj;
 	struct user_namespace *fs_userns = i_user_ns(inode);
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	int found = 0;
 	vfsuid_t vfsuid;
 	vfsgid_t vfsgid;
@@ -683,7 +684,7 @@ EXPORT_SYMBOL_GPL(posix_acl_create);
 
 /**
  * posix_acl_update_mode  -  update mode in set_acl
- * @mnt_userns:	user namespace of the mount @inode was found from
+ * @idmap:	idmap of the mount @inode was found from
  * @inode:	target inode
  * @mode_p:	mode (pointer) for update
  * @acl:	acl pointer
@@ -695,18 +696,19 @@ EXPORT_SYMBOL_GPL(posix_acl_create);
  * As with chmod, clear the setgid bit if the caller is not in the owning group
  * or capable of CAP_FSETID (see inode_change_ok).
  *
- * If the inode 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 inode 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.
  *
  * Called from set_acl inode operations.
  */
-int posix_acl_update_mode(struct user_namespace *mnt_userns,
+int posix_acl_update_mode(struct mnt_idmap *idmap,
 			  struct inode *inode, umode_t *mode_p,
 			  struct posix_acl **acl)
 {
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	umode_t mode = inode->i_mode;
 	int error;
 
@@ -982,11 +984,10 @@ 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) {
-		error = posix_acl_update_mode(mnt_userns, inode,
+		error = posix_acl_update_mode(idmap, inode,
 				&inode->i_mode, &acl);
 		if (error)
 			return error;
@@ -1018,10 +1019,12 @@ int simple_acl_create(struct inode *dir, struct inode *inode)
 	return 0;
 }
 
-static int vfs_set_acl_idmapped_mnt(struct user_namespace *mnt_userns,
+static int vfs_set_acl_idmapped_mnt(struct mnt_idmap *idmap,
 				    struct user_namespace *fs_userns,
 				    struct posix_acl *acl)
 {
+	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
+
 	for (int n = 0; n < acl->a_count; n++) {
 		struct posix_acl_entry *acl_e = &acl->a_entries[n];
 
@@ -1057,7 +1060,6 @@ int vfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 {
 	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;
 
@@ -1073,7 +1075,7 @@ int vfs_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 		 * if this is a filesystem with a backing store - ultimately
 		 * translate them to backing store values.
 		 */
-		error = vfs_set_acl_idmapped_mnt(mnt_userns, i_user_ns(inode), kacl);
+		error = vfs_set_acl_idmapped_mnt(idmap, i_user_ns(inode), kacl);
 		if (error)
 			return error;
 	}
@@ -1089,7 +1091,7 @@ retry_deleg:
 	if (error)
 		goto out_inode_unlock;
 
-	error = security_inode_set_acl(mnt_userns, dentry, acl_name, kacl);
+	error = security_inode_set_acl(idmap, dentry, acl_name, kacl);
 	if (error)
 		goto out_inode_unlock;
 
@@ -1135,7 +1137,6 @@ EXPORT_SYMBOL_GPL(vfs_set_acl);
 struct posix_acl *vfs_get_acl(struct mnt_idmap *idmap,
 			      struct dentry *dentry, const char *acl_name)
 {
-	struct user_namespace *mnt_userns = mnt_idmap_owner(idmap);
 	struct inode *inode = d_inode(dentry);
 	struct posix_acl *acl;
 	int acl_type, error;
@@ -1148,7 +1149,7 @@ struct posix_acl *vfs_get_acl(struct mnt_idmap *idmap,
 	 * The VFS has no restrictions on reading POSIX ACLs so calling
 	 * something like xattr_permission() isn't needed. Only LSMs get a say.
 	 */
-	error = security_inode_get_acl(mnt_userns, dentry, acl_name);
+	error = security_inode_get_acl(idmap, dentry, acl_name);
 	if (error)
 		return ERR_PTR(error);
 
@@ -1182,7 +1183,6 @@ int vfs_remove_acl(struct mnt_idmap *idmap, struct dentry *dentry,
 {
 	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;
 
@@ -1201,7 +1201,7 @@ retry_deleg:
 	if (error)
 		goto out_inode_unlock;
 
-	error = security_inode_remove_acl(mnt_userns, dentry, acl_name);
+	error = security_inode_remove_acl(idmap, dentry, acl_name);
 	if (error)
 		goto out_inode_unlock;
 
@@ -1217,7 +1217,7 @@ retry_deleg:
 		error = -EOPNOTSUPP;
 	if (!error) {
 		fsnotify_xattr(dentry);
-		evm_inode_post_remove_acl(mnt_userns, dentry, acl_name);
+		evm_inode_post_remove_acl(idmap, dentry, acl_name);
 	}
 
 out_inode_unlock: