1 files changed, 59 insertions, 21 deletions

diff --git a/fs/efivarfs/file.c b/fs/efivarfs/file.c
index 8dd524f32284..cb1b6d0c3454 100644
--- a/fs/efivarfs/file.c
+++ b/fs/efivarfs/file.c
@@ -1,15 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2012 Red Hat, Inc.
  * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
  */
 
 #include <linux/efi.h>
+#include <linux/delay.h>
 #include <linux/fs.h>
 #include <linux/slab.h>
+#include <linux/mount.h>
 
 #include "internal.h"
 
@@ -21,7 +20,7 @@ static ssize_t efivarfs_file_write(struct file *file,
 	u32 attributes;
 	struct inode *inode = file->f_mapping->host;
 	unsigned long datasize = count - sizeof(attributes);
-	ssize_t bytes = 0;
+	ssize_t bytes;
 	bool set = false;
 
 	if (count < sizeof(attributes))
@@ -33,36 +32,45 @@ static ssize_t efivarfs_file_write(struct file *file,
 	if (attributes & ~(EFI_VARIABLE_MASK))
 		return -EINVAL;
 
-	data = kmalloc(datasize, GFP_KERNEL);
-	if (!data)
-		return -ENOMEM;
-
-	if (copy_from_user(data, userbuf + sizeof(attributes), datasize)) {
-		bytes = -EFAULT;
+	data = memdup_user(userbuf + sizeof(attributes), datasize);
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	inode_lock(inode);
+	if (var->removed) {
+		/*
+		 * file got removed; don't allow a set.  Caused by an
+		 * unsuccessful create or successful delete write
+		 * racing with us.
+		 */
+		bytes = -EIO;
 		goto out;
 	}
 
 	bytes = efivar_entry_set_get_size(var, attributes, &datasize,
 					  data, &set);
-	if (!set && bytes) {
+	if (!set) {
 		if (bytes == -ENOENT)
 			bytes = -EIO;
 		goto out;
 	}
 
 	if (bytes == -ENOENT) {
-		drop_nlink(inode);
-		d_delete(file->f_dentry);
-		dput(file->f_dentry);
+		/*
+		 * zero size signals to release that the write deleted
+		 * the variable
+		 */
+		i_size_write(inode, 0);
 	} else {
-		mutex_lock(&inode->i_mutex);
 		i_size_write(inode, datasize + sizeof(attributes));
-		mutex_unlock(&inode->i_mutex);
+		inode_set_mtime_to_ts(inode, inode_set_ctime_current(inode));
 	}
 
 	bytes = count;
 
 out:
+	inode_unlock(inode);
+
 	kfree(data);
 
 	return bytes;
@@ -78,6 +86,9 @@ static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 	ssize_t size = 0;
 	int err;
 
+	while (!__ratelimit(&file->f_cred->user->ratelimit))
+		msleep(50);
+
 	err = efivar_entry_size(var, &datasize);
 
 	/*
@@ -108,9 +119,36 @@ out_free:
 	return size;
 }
 
+static int efivarfs_file_release(struct inode *inode, struct file *file)
+{
+	struct efivar_entry *var = inode->i_private;
+
+	inode_lock(inode);
+	var->removed = (--var->open_count == 0 && i_size_read(inode) == 0);
+	inode_unlock(inode);
+
+	if (var->removed)
+		simple_recursive_removal(file->f_path.dentry, NULL);
+
+	return 0;
+}
+
+static int efivarfs_file_open(struct inode *inode, struct file *file)
+{
+	struct efivar_entry *entry = inode->i_private;
+
+	file->private_data = entry;
+
+	inode_lock(inode);
+	entry->open_count++;
+	inode_unlock(inode);
+
+	return 0;
+}
+
 const struct file_operations efivarfs_file_operations = {
-	.open	= simple_open,
-	.read	= efivarfs_file_read,
-	.write	= efivarfs_file_write,
-	.llseek	= no_llseek,
+	.open		= efivarfs_file_open,
+	.read		= efivarfs_file_read,
+	.write		= efivarfs_file_write,
+	.release	= efivarfs_file_release,
 };