ovl: mark parent impure on ovl_link()

When linking a file with copy up origin into a new parent, mark the
new parent dir "impure".

Fixes: ee1d6d37b6b8 ("ovl: mark upper dir with type origin entries "impure"")
Cc: <stable@vger.kernel.org> # v4.12
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/dir.c

@@ -481,17 +481,30 @@ out_cleanup:
 }
 
 static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
-			      struct cattr *attr, struct dentry *hardlink)
+			      struct cattr *attr, struct dentry *hardlink,
+			      bool origin)
 {
 	int err;
 	const struct cred *old_cred;
 	struct cred *override_cred;
+	struct dentry *parent = dentry->d_parent;
 
-	err = ovl_copy_up(dentry->d_parent);
+	err = ovl_copy_up(parent);
 	if (err)
 		return err;
 
 	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;
+	}
+
 	err = -ENOMEM;
 	override_cred = prepare_creds();
 	if (override_cred) {
@@ -550,7 +563,7 @@ static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
 	inode_init_owner(inode, dentry->d_parent->d_inode, mode);
 	attr.mode = inode->i_mode;
 
-	err = ovl_create_or_link(dentry, inode, &attr, NULL);
+	err = ovl_create_or_link(dentry, inode, &attr, NULL, false);
 	if (err)
 		iput(inode);
 
@@ -609,7 +622,8 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
 	inode = d_inode(old);
 	ihold(inode);
 
-	err = ovl_create_or_link(new, inode, NULL, ovl_dentry_upper(old));
+	err = ovl_create_or_link(new, inode, NULL, ovl_dentry_upper(old),
+				 ovl_type_origin(old));
 	if (err)
 		iput(inode);