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/delay.h>
 12#include <linux/fs.h>
 13#include <linux/slab.h>
 14#include <linux/mount.h>
 15
 16#include "internal.h"
 17
 18static ssize_t efivarfs_file_write(struct file *file,
 19		const char __user *userbuf, size_t count, loff_t *ppos)
 20{
 21	struct efivar_entry *var = file->private_data;
 22	void *data;
 23	u32 attributes;
 24	struct inode *inode = file->f_mapping->host;
 25	unsigned long datasize = count - sizeof(attributes);
 26	ssize_t bytes;
 27	bool set = false;
 28
 29	if (count < sizeof(attributes))
 30		return -EINVAL;
 31
 32	if (copy_from_user(&attributes, userbuf, sizeof(attributes)))
 33		return -EFAULT;
 34
 35	if (attributes & ~(EFI_VARIABLE_MASK))
 36		return -EINVAL;
 37
 38	data = memdup_user(userbuf + sizeof(attributes), datasize);
 39	if (IS_ERR(data))
 40		return PTR_ERR(data);
 41
 42	bytes = efivar_entry_set_get_size(var, attributes, &datasize,
 43					  data, &set);
 44	if (!set && bytes) {
 45		if (bytes == -ENOENT)
 46			bytes = -EIO;
 47		goto out;
 48	}
 49
 50	if (bytes == -ENOENT) {
 51		drop_nlink(inode);
 52		d_delete(file->f_path.dentry);
 53		dput(file->f_path.dentry);
 54	} else {
 55		inode_lock(inode);
 56		i_size_write(inode, datasize + sizeof(attributes));
 57		inode_unlock(inode);
 58	}
 59
 60	bytes = count;
 61
 62out:
 63	kfree(data);
 64
 65	return bytes;
 66}
 67
 68static ssize_t efivarfs_file_read(struct file *file, char __user *userbuf,
 69		size_t count, loff_t *ppos)
 70{
 71	struct efivar_entry *var = file->private_data;
 72	unsigned long datasize = 0;
 73	u32 attributes;
 74	void *data;
 75	ssize_t size = 0;
 76	int err;
 77
 78	while (!__ratelimit(&file->f_cred->user->ratelimit)) {
 79		if (!msleep_interruptible(50))
 80			return -EINTR;
 81	}
 82
 83	err = efivar_entry_size(var, &datasize);
 84
 85	/*
 86	 * efivarfs represents uncommitted variables with
 87	 * zero-length files. Reading them should return EOF.
 88	 */
 89	if (err == -ENOENT)
 90		return 0;
 91	else if (err)
 92		return err;
 93
 94	data = kmalloc(datasize + sizeof(attributes), GFP_KERNEL);
 95
 96	if (!data)
 97		return -ENOMEM;
 98
 99	size = efivar_entry_get(var, &attributes, &datasize,
100				data + sizeof(attributes));
101	if (size)
102		goto out_free;
103
104	memcpy(data, &attributes, sizeof(attributes));
105	size = simple_read_from_buffer(userbuf, count, ppos,
106				       data, datasize + sizeof(attributes));
107out_free:
108	kfree(data);
109
110	return size;
111}
112
113static int
114efivarfs_ioc_getxflags(struct file *file, void __user *arg)
115{
116	struct inode *inode = file->f_mapping->host;
117	unsigned int i_flags;
118	unsigned int flags = 0;
119
120	i_flags = inode->i_flags;
121	if (i_flags & S_IMMUTABLE)
122		flags |= FS_IMMUTABLE_FL;
123
124	if (copy_to_user(arg, &flags, sizeof(flags)))
125		return -EFAULT;
126	return 0;
127}
128
129static int
130efivarfs_ioc_setxflags(struct file *file, void __user *arg)
131{
132	struct inode *inode = file->f_mapping->host;
133	unsigned int flags;
134	unsigned int i_flags = 0;
135	int error;
136
137	if (!inode_owner_or_capable(inode))
138		return -EACCES;
139
140	if (copy_from_user(&flags, arg, sizeof(flags)))
141		return -EFAULT;
142
143	if (flags & ~FS_IMMUTABLE_FL)
144		return -EOPNOTSUPP;
145
146	if (!capable(CAP_LINUX_IMMUTABLE))
147		return -EPERM;
148
149	if (flags & FS_IMMUTABLE_FL)
150		i_flags |= S_IMMUTABLE;
151
152
153	error = mnt_want_write_file(file);
154	if (error)
155		return error;
156
157	inode_lock(inode);
158	inode_set_flags(inode, i_flags, S_IMMUTABLE);
159	inode_unlock(inode);
160
161	mnt_drop_write_file(file);
162
163	return 0;
164}
165
166static long
167efivarfs_file_ioctl(struct file *file, unsigned int cmd, unsigned long p)
168{
169	void __user *arg = (void __user *)p;
170
171	switch (cmd) {
172	case FS_IOC_GETFLAGS:
173		return efivarfs_ioc_getxflags(file, arg);
174	case FS_IOC_SETFLAGS:
175		return efivarfs_ioc_setxflags(file, arg);
176	}
177
178	return -ENOTTY;
179}
180
181const struct file_operations efivarfs_file_operations = {
182	.open	= simple_open,
183	.read	= efivarfs_file_read,
184	.write	= efivarfs_file_write,
185	.llseek	= no_llseek,
186	.unlocked_ioctl = efivarfs_file_ioctl,
187};