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/ctype.h>
11#include <linux/efi.h>
12#include <linux/fs.h>
13#include <linux/module.h>
14#include <linux/pagemap.h>
15#include <linux/ucs2_string.h>
16#include <linux/slab.h>
17#include <linux/magic.h>
18
19#include "internal.h"
20
21LIST_HEAD(efivarfs_list);
22
23static void efivarfs_evict_inode(struct inode *inode)
24{
25	clear_inode(inode);
26}
27
28static const struct super_operations efivarfs_ops = {
29	.statfs = simple_statfs,
30	.drop_inode = generic_delete_inode,
31	.evict_inode = efivarfs_evict_inode,
32	.show_options = generic_show_options,
33};
34
35static struct super_block *efivarfs_sb;
36
37/*
38 * Compare two efivarfs file names.
39 *
40 * An efivarfs filename is composed of two parts,
41 *
42 *	1. A case-sensitive variable name
43 *	2. A case-insensitive GUID
44 *
45 * So we need to perform a case-sensitive match on part 1 and a
46 * case-insensitive match on part 2.
47 */
48static int efivarfs_d_compare(const struct dentry *parent,
49			      const struct dentry *dentry,
50			      unsigned int len, const char *str,
51			      const struct qstr *name)
52{
53	int guid = len - EFI_VARIABLE_GUID_LEN;
54
55	if (name->len != len)
56		return 1;
57
58	/* Case-sensitive compare for the variable name */
59	if (memcmp(str, name->name, guid))
60		return 1;
61
62	/* Case-insensitive compare for the GUID */
63	return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN);
64}
65
66static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr)
67{
68	unsigned long hash = init_name_hash();
69	const unsigned char *s = qstr->name;
70	unsigned int len = qstr->len;
71
72	if (!efivarfs_valid_name(s, len))
73		return -EINVAL;
74
75	while (len-- > EFI_VARIABLE_GUID_LEN)
76		hash = partial_name_hash(*s++, hash);
77
78	/* GUID is case-insensitive. */
79	while (len--)
80		hash = partial_name_hash(tolower(*s++), hash);
81
82	qstr->hash = end_name_hash(hash);
83	return 0;
84}
85
86static const struct dentry_operations efivarfs_d_ops = {
87	.d_compare = efivarfs_d_compare,
88	.d_hash = efivarfs_d_hash,
89	.d_delete = always_delete_dentry,
90};
91
92static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name)
93{
94	struct dentry *d;
95	struct qstr q;
96	int err;
97
98	q.name = name;
99	q.len = strlen(name);
100
101	err = efivarfs_d_hash(NULL, &q);
102	if (err)
103		return ERR_PTR(err);
104
105	d = d_alloc(parent, &q);
106	if (d)
107		return d;
108
109	return ERR_PTR(-ENOMEM);
110}
111
112static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor,
113			     unsigned long name_size, void *data)
114{
115	struct super_block *sb = (struct super_block *)data;
116	struct efivar_entry *entry;
117	struct inode *inode = NULL;
118	struct dentry *dentry, *root = sb->s_root;
119	unsigned long size = 0;
120	char *name;
121	int len;
122	int err = -ENOMEM;
123	bool is_removable = false;
124
125	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
126	if (!entry)
127		return err;
128
129	memcpy(entry->var.VariableName, name16, name_size);
130	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
131
132	len = ucs2_utf8size(entry->var.VariableName);
133
134	/* name, plus '-', plus GUID, plus NUL*/
135	name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL);
136	if (!name)
137		goto fail;
138
139	ucs2_as_utf8(name, entry->var.VariableName, len);
140
141	if (efivar_variable_is_removable(entry->var.VendorGuid, name, len))
142		is_removable = true;
143
144	name[len] = '-';
145
146	efi_guid_to_str(&entry->var.VendorGuid, name + len + 1);
147
148	name[len + EFI_VARIABLE_GUID_LEN+1] = '\0';
149
150	inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,
151				   is_removable);
152	if (!inode)
153		goto fail_name;
154
155	dentry = efivarfs_alloc_dentry(root, name);
156	if (IS_ERR(dentry)) {
157		err = PTR_ERR(dentry);
158		goto fail_inode;
159	}
160
161	/* copied by the above to local storage in the dentry. */
162	kfree(name);
163
164	efivar_entry_size(entry, &size);
165	efivar_entry_add(entry, &efivarfs_list);
166
167	mutex_lock(&inode->i_mutex);
168	inode->i_private = entry;
169	i_size_write(inode, size + sizeof(entry->var.Attributes));
170	mutex_unlock(&inode->i_mutex);
171	d_add(dentry, inode);
172
173	return 0;
174
175fail_inode:
176	iput(inode);
177fail_name:
178	kfree(name);
179fail:
180	kfree(entry);
181	return err;
182}
183
184static int efivarfs_destroy(struct efivar_entry *entry, void *data)
185{
186	efivar_entry_remove(entry);
187	kfree(entry);
188	return 0;
189}
190
191static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
192{
193	struct inode *inode = NULL;
194	struct dentry *root;
195	int err;
196
197	efivarfs_sb = sb;
198
199	sb->s_maxbytes          = MAX_LFS_FILESIZE;
200	sb->s_blocksize         = PAGE_CACHE_SIZE;
201	sb->s_blocksize_bits    = PAGE_CACHE_SHIFT;
202	sb->s_magic             = EFIVARFS_MAGIC;
203	sb->s_op                = &efivarfs_ops;
204	sb->s_d_op		= &efivarfs_d_ops;
205	sb->s_time_gran         = 1;
206
207	inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true);
208	if (!inode)
209		return -ENOMEM;
210	inode->i_op = &efivarfs_dir_inode_operations;
211
212	root = d_make_root(inode);
213	sb->s_root = root;
214	if (!root)
215		return -ENOMEM;
216
217	INIT_LIST_HEAD(&efivarfs_list);
218
219	err = efivar_init(efivarfs_callback, (void *)sb, false,
220			  true, &efivarfs_list);
221	if (err)
222		__efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
223
224	return err;
225}
226
227static struct dentry *efivarfs_mount(struct file_system_type *fs_type,
228				    int flags, const char *dev_name, void *data)
229{
230	return mount_single(fs_type, flags, data, efivarfs_fill_super);
231}
232
233static void efivarfs_kill_sb(struct super_block *sb)
234{
235	kill_litter_super(sb);
236	efivarfs_sb = NULL;
237
238	/* Remove all entries and destroy */
239	__efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
240}
241
242static struct file_system_type efivarfs_type = {
243	.owner   = THIS_MODULE,
244	.name    = "efivarfs",
245	.mount   = efivarfs_mount,
246	.kill_sb = efivarfs_kill_sb,
247};
248
249static __init int efivarfs_init(void)
250{
251	if (!efi_enabled(EFI_RUNTIME_SERVICES))
252		return -ENODEV;
253
254	if (!efivars_kobject())
255		return -ENODEV;
256
257	return register_filesystem(&efivarfs_type);
258}
259
260static __exit void efivarfs_exit(void)
261{
262	unregister_filesystem(&efivarfs_type);
263}
264
265MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr");
266MODULE_DESCRIPTION("EFI Variable Filesystem");
267MODULE_LICENSE("GPL");
268MODULE_ALIAS_FS("efivarfs");
269
270module_init(efivarfs_init);
271module_exit(efivarfs_exit);
272