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
21 LIST_HEAD(efivarfs_list);
22
efivarfs_evict_inode(struct inode * inode)23 static void efivarfs_evict_inode(struct inode *inode)
24 {
25 clear_inode(inode);
26 }
27
28 static 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
35 static 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 */
efivarfs_d_compare(const struct dentry * parent,const struct dentry * dentry,unsigned int len,const char * str,const struct qstr * name)48 static 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
efivarfs_d_hash(const struct dentry * dentry,struct qstr * qstr)66 static 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
86 static 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
efivarfs_alloc_dentry(struct dentry * parent,char * name)92 static 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
efivarfs_callback(efi_char16_t * name16,efi_guid_t vendor,unsigned long name_size,void * data)112 static 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 /* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */
151 strreplace(name, '/', '!');
152
153 inode = efivarfs_get_inode(sb, d_inode(root), S_IFREG | 0644, 0,
154 is_removable);
155 if (!inode)
156 goto fail_name;
157
158 dentry = efivarfs_alloc_dentry(root, name);
159 if (IS_ERR(dentry)) {
160 err = PTR_ERR(dentry);
161 goto fail_inode;
162 }
163
164 /* copied by the above to local storage in the dentry. */
165 kfree(name);
166
167 efivar_entry_size(entry, &size);
168 efivar_entry_add(entry, &efivarfs_list);
169
170 mutex_lock(&inode->i_mutex);
171 inode->i_private = entry;
172 i_size_write(inode, size + sizeof(entry->var.Attributes));
173 mutex_unlock(&inode->i_mutex);
174 d_add(dentry, inode);
175
176 return 0;
177
178 fail_inode:
179 iput(inode);
180 fail_name:
181 kfree(name);
182 fail:
183 kfree(entry);
184 return err;
185 }
186
efivarfs_destroy(struct efivar_entry * entry,void * data)187 static int efivarfs_destroy(struct efivar_entry *entry, void *data)
188 {
189 efivar_entry_remove(entry);
190 kfree(entry);
191 return 0;
192 }
193
efivarfs_fill_super(struct super_block * sb,void * data,int silent)194 static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
195 {
196 struct inode *inode = NULL;
197 struct dentry *root;
198 int err;
199
200 efivarfs_sb = sb;
201
202 sb->s_maxbytes = MAX_LFS_FILESIZE;
203 sb->s_blocksize = PAGE_CACHE_SIZE;
204 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
205 sb->s_magic = EFIVARFS_MAGIC;
206 sb->s_op = &efivarfs_ops;
207 sb->s_d_op = &efivarfs_d_ops;
208 sb->s_time_gran = 1;
209
210 inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0, true);
211 if (!inode)
212 return -ENOMEM;
213 inode->i_op = &efivarfs_dir_inode_operations;
214
215 root = d_make_root(inode);
216 sb->s_root = root;
217 if (!root)
218 return -ENOMEM;
219
220 INIT_LIST_HEAD(&efivarfs_list);
221
222 err = efivar_init(efivarfs_callback, (void *)sb, false,
223 true, &efivarfs_list);
224 if (err)
225 __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
226
227 return err;
228 }
229
efivarfs_mount(struct file_system_type * fs_type,int flags,const char * dev_name,void * data)230 static struct dentry *efivarfs_mount(struct file_system_type *fs_type,
231 int flags, const char *dev_name, void *data)
232 {
233 return mount_single(fs_type, flags, data, efivarfs_fill_super);
234 }
235
efivarfs_kill_sb(struct super_block * sb)236 static void efivarfs_kill_sb(struct super_block *sb)
237 {
238 kill_litter_super(sb);
239 efivarfs_sb = NULL;
240
241 /* Remove all entries and destroy */
242 __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL);
243 }
244
245 static struct file_system_type efivarfs_type = {
246 .owner = THIS_MODULE,
247 .name = "efivarfs",
248 .mount = efivarfs_mount,
249 .kill_sb = efivarfs_kill_sb,
250 };
251
efivarfs_init(void)252 static __init int efivarfs_init(void)
253 {
254 if (!efi_enabled(EFI_RUNTIME_SERVICES))
255 return -ENODEV;
256
257 if (!efivars_kobject())
258 return -ENODEV;
259
260 return register_filesystem(&efivarfs_type);
261 }
262
efivarfs_exit(void)263 static __exit void efivarfs_exit(void)
264 {
265 unregister_filesystem(&efivarfs_type);
266 }
267
268 MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr");
269 MODULE_DESCRIPTION("EFI Variable Filesystem");
270 MODULE_LICENSE("GPL");
271 MODULE_ALIAS_FS("efivarfs");
272
273 module_init(efivarfs_init);
274 module_exit(efivarfs_exit);
275