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