ovl: port ovl_create_or_link() to cred guard

Use the scoped ovl cred guard.

Link: https://patch.msgid.link/20251117-work-ovl-cred-guard-v4-3-b31603935724@kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 10e2b7e41a7aa5e326864c133e95a200cb449f27..c3492b040fba90d665462d161fd77f214312fbda 100644 (file)
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -618,52 +618,44 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
                              struct ovl_cattr *attr, bool origin)
 {
        int err;
-       const struct cred *old_cred, *new_cred = NULL;
+       const struct cred *new_cred __free(put_cred) = NULL;
        struct dentry *parent = dentry->d_parent;
 
-       old_cred = ovl_override_creds(dentry->d_sb);
-
-       /*
-        * When linking a file with copy up origin into a new parent, mark the
-        * new parent dir "impure".
-        */
-       if (origin) {
-               err = ovl_set_impure(parent, ovl_dentry_upper(parent));
-               if (err)
-                       goto out_revert_creds;
-       }
-
-       if (!attr->hardlink) {
+       scoped_class(override_creds_ovl, old_cred, dentry->d_sb) {
                /*
-                * In the creation cases(create, mkdir, mknod, symlink),
-                * ovl should transfer current's fs{u,g}id to underlying
-                * fs. Because underlying fs want to initialize its new
-                * inode owner using current's fs{u,g}id. And in this
-                * case, the @inode is a new inode that is initialized
-                * in inode_init_owner() to current's fs{u,g}id. So use
-                * the inode's i_{u,g}id to override the cred's fs{u,g}id.
-                *
-                * But in the other hardlink case, ovl_link() does not
-                * create a new inode, so just use the ovl mounter's
-                * fs{u,g}id.
+                * When linking a file with copy up origin into a new parent, mark the
+                * new parent dir "impure".
                 */
-               new_cred = ovl_setup_cred_for_create(dentry, inode, attr->mode,
-                                                    old_cred);
-               err = PTR_ERR(new_cred);
-               if (IS_ERR(new_cred)) {
-                       new_cred = NULL;
-                       goto out_revert_creds;
+               if (origin) {
+                       err = ovl_set_impure(parent, ovl_dentry_upper(parent));
+                       if (err)
+                               return err;
                }
-       }
 
-       if (!ovl_dentry_is_whiteout(dentry))
-               err = ovl_create_upper(dentry, inode, attr);
-       else
-               err = ovl_create_over_whiteout(dentry, inode, attr);
+               if (!attr->hardlink) {
+                       /*
+                        * In the creation cases(create, mkdir, mknod, symlink),
+                        * ovl should transfer current's fs{u,g}id to underlying
+                        * fs. Because underlying fs want to initialize its new
+                        * inode owner using current's fs{u,g}id. And in this
+                        * case, the @inode is a new inode that is initialized
+                        * in inode_init_owner() to current's fs{u,g}id. So use
+                        * the inode's i_{u,g}id to override the cred's fs{u,g}id.
+                        *
+                        * But in the other hardlink case, ovl_link() does not
+                        * create a new inode, so just use the ovl mounter's
+                        * fs{u,g}id.
+                        */
+                       new_cred = ovl_setup_cred_for_create(dentry, inode, attr->mode, old_cred);
+                       if (IS_ERR(new_cred))
+                               return PTR_ERR(new_cred);
+               }
 
-out_revert_creds:
-       ovl_revert_creds(old_cred);
-       put_cred(new_cred);
+               if (!ovl_dentry_is_whiteout(dentry))
+                       return ovl_create_upper(dentry, inode, attr);
+
+               return ovl_create_over_whiteout(dentry, inode, attr);
+       }
        return err;
 }