1/*
  2 * Copyright (C) 2012 Red Hat, Inc.
  3 * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com>
  4 *
  5 * This program is free software; you can redistribute it and/or modify
  6 * it under the terms of the GNU General Public License version 2 as
  7 * published by the Free Software Foundation.
  8 */
  9
 10#include <linux/efi.h>
 11#include <linux/fs.h>
 12#include <linux/slab.h>
 13
 14#include "internal.h"
 15
 16static ssize_t efivarfs_file_write(struct file *file,
 17		const char __user *userbuf, size_t count, loff_t *ppos)
 18{
 19	struct efivar_entry *var = file->private_data;
 20	void *data;
 21	u32 attributes;
 22	struct inode *inode = file->f_mapping->host;
 23	unsigned long datasize = count - sizeof(attributes);
 24	ssize_t bytes;
 25	bool set = false;
 26
 27	if (count < sizeof(attributes))
 28		return -EINVAL;
 29
 30	if (copy_from_user(&attributes, userbuf, sizeof(attributes)))
 31		return -EFAULT;
 32
 33	if (attributes & ~(EFI_VARIABLE_MASK))
 34		return -EINVAL;
 35
 36	data = memdup_user(userbuf + sizeof(attributes), datasize);
 37	if (IS_ERR(data))
 38		return PTR_ERR(data);
 39
 40	bytes = efivar_entry_set_get_size(var, attributes, &datasize,
 41					  data, &set);
 42	if (!set && bytes) {
 43		if (bytes == -ENOENT)
 44			bytes = -EIO;
 45		goto out;
 46	}
 47
 48	if (bytes == -ENOENT) {
 49		drop_nlink(inode);
 50		d_delete(file->f_dentry);
 51		dput(file->f_dentry);
 52	} else {
 53		mutex_lock(&inode->i_mutex);
 54		i_size_write(inode, datasize + sizeof(attributes));
 55		mutex_unlock(&inode->i_mutex);
 56	}
 57
 58	bytes = count;
 59
 60out:
 61	kfree(data);
 62
 63	return bytes;
 64}
 65
 66static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 67		size_t count, loff_t *ppos)
 68{
 69	struct efivar_entry *var = file->private_data;
 70	unsigned long datasize = 0;
 71	u32 attributes;
 72	void *data;
 73	ssize_t size = 0;
 74	int err;
 75
 76	err = efivar_entry_size(var, &datasize);
 77
 78	/*
 79	 * efivarfs represents uncommitted variables with
 80	 * zero-length files. Reading them should return EOF.
 81	 */
 82	if (err == -ENOENT)
 83		return 0;
 84	else if (err)
 85		return err;
 86
 87	data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL);
 88
 89	if (!data)
 90		return -ENOMEM;
 91
 92	size = efivar_entry_get(var, &attributes, &datasize,
 93				data + sizeof(attributes));
 94	if (size)
 95		goto out_free;
 96
 97	memcpy(data, &attributes, sizeof(attributes));
 98	size = simple_read_from_buffer(userbuf, count, ppos,
 99				       data, datasize + sizeof(attributes));
100out_free:
101	kfree(data);
102
103	return size;
104}
105
106const struct file_operations efivarfs_file_operations = {
107	.open	= simple_open,
108	.read	= efivarfs_file_read,
109	.write	= efivarfs_file_write,
110	.llseek	= no_llseek,
111};