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d68772b7 MF |
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> | |
a614e192 | 15 | #include <linux/ucs2_string.h> |
d68772b7 MF |
16 | |
17 | #include "internal.h" | |
18 | ||
19 | LIST_HEAD(efivarfs_list); | |
20 | ||
21 | static void efivarfs_evict_inode(struct inode *inode) | |
22 | { | |
23 | clear_inode(inode); | |
24 | } | |
25 | ||
26 | static const struct super_operations efivarfs_ops = { | |
27 | .statfs = simple_statfs, | |
28 | .drop_inode = generic_delete_inode, | |
29 | .evict_inode = efivarfs_evict_inode, | |
30 | .show_options = generic_show_options, | |
31 | }; | |
32 | ||
33 | static struct super_block *efivarfs_sb; | |
34 | ||
35 | /* | |
36 | * Compare two efivarfs file names. | |
37 | * | |
38 | * An efivarfs filename is composed of two parts, | |
39 | * | |
40 | * 1. A case-sensitive variable name | |
41 | * 2. A case-insensitive GUID | |
42 | * | |
43 | * So we need to perform a case-sensitive match on part 1 and a | |
44 | * case-insensitive match on part 2. | |
45 | */ | |
46 | static int efivarfs_d_compare(const struct dentry *parent, const struct inode *pinode, | |
47 | const struct dentry *dentry, const struct inode *inode, | |
48 | unsigned int len, const char *str, | |
49 | const struct qstr *name) | |
50 | { | |
51 | int guid = len - EFI_VARIABLE_GUID_LEN; | |
52 | ||
53 | if (name->len != len) | |
54 | return 1; | |
55 | ||
56 | /* Case-sensitive compare for the variable name */ | |
57 | if (memcmp(str, name->name, guid)) | |
58 | return 1; | |
59 | ||
60 | /* Case-insensitive compare for the GUID */ | |
61 | return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN); | |
62 | } | |
63 | ||
64 | static int efivarfs_d_hash(const struct dentry *dentry, | |
65 | const struct inode *inode, struct qstr *qstr) | |
66 | { | |
67 | unsigned long hash = init_name_hash(); | |
68 | const unsigned char *s = qstr->name; | |
69 | unsigned int len = qstr->len; | |
70 | ||
71 | if (!efivarfs_valid_name(s, len)) | |
72 | return -EINVAL; | |
73 | ||
74 | while (len-- > EFI_VARIABLE_GUID_LEN) | |
75 | hash = partial_name_hash(*s++, hash); | |
76 | ||
77 | /* GUID is case-insensitive. */ | |
78 | while (len--) | |
79 | hash = partial_name_hash(tolower(*s++), hash); | |
80 | ||
81 | qstr->hash = end_name_hash(hash); | |
82 | return 0; | |
83 | } | |
84 | ||
85 | /* | |
86 | * Retaining negative dentries for an in-memory filesystem just wastes | |
87 | * memory and lookup time: arrange for them to be deleted immediately. | |
88 | */ | |
89 | static int efivarfs_delete_dentry(const struct dentry *dentry) | |
90 | { | |
91 | return 1; | |
92 | } | |
93 | ||
94 | static struct dentry_operations efivarfs_d_ops = { | |
95 | .d_compare = efivarfs_d_compare, | |
96 | .d_hash = efivarfs_d_hash, | |
97 | .d_delete = efivarfs_delete_dentry, | |
98 | }; | |
99 | ||
100 | static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name) | |
101 | { | |
102 | struct dentry *d; | |
103 | struct qstr q; | |
104 | int err; | |
105 | ||
106 | q.name = name; | |
107 | q.len = strlen(name); | |
108 | ||
109 | err = efivarfs_d_hash(NULL, NULL, &q); | |
110 | if (err) | |
111 | return ERR_PTR(err); | |
112 | ||
113 | d = d_alloc(parent, &q); | |
114 | if (d) | |
115 | return d; | |
116 | ||
117 | return ERR_PTR(-ENOMEM); | |
118 | } | |
119 | ||
120 | static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor, | |
121 | unsigned long name_size, void *data) | |
122 | { | |
123 | struct super_block *sb = (struct super_block *)data; | |
124 | struct efivar_entry *entry; | |
125 | struct inode *inode = NULL; | |
126 | struct dentry *dentry, *root = sb->s_root; | |
127 | unsigned long size = 0; | |
128 | char *name; | |
129 | int len, i; | |
130 | int err = -ENOMEM; | |
131 | ||
132 | entry = kmalloc(sizeof(*entry), GFP_KERNEL); | |
133 | if (!entry) | |
134 | return err; | |
135 | ||
136 | memcpy(entry->var.VariableName, name16, name_size); | |
137 | memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t)); | |
138 | ||
a614e192 | 139 | len = ucs2_strlen(entry->var.VariableName); |
d68772b7 MF |
140 | |
141 | /* name, plus '-', plus GUID, plus NUL*/ | |
142 | name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL); | |
143 | if (!name) | |
144 | goto fail; | |
145 | ||
146 | for (i = 0; i < len; i++) | |
147 | name[i] = entry->var.VariableName[i] & 0xFF; | |
148 | ||
149 | name[len] = '-'; | |
150 | ||
151 | efi_guid_unparse(&entry->var.VendorGuid, name + len + 1); | |
152 | ||
153 | name[len + EFI_VARIABLE_GUID_LEN+1] = '\0'; | |
154 | ||
155 | inode = efivarfs_get_inode(sb, root->d_inode, S_IFREG | 0644, 0); | |
156 | if (!inode) | |
157 | goto fail_name; | |
158 | ||
159 | dentry = efivarfs_alloc_dentry(root, name); | |
160 | if (IS_ERR(dentry)) { | |
161 | err = PTR_ERR(dentry); | |
162 | goto fail_inode; | |
163 | } | |
164 | ||
165 | /* copied by the above to local storage in the dentry. */ | |
166 | kfree(name); | |
167 | ||
168 | efivar_entry_size(entry, &size); | |
169 | efivar_entry_add(entry, &efivarfs_list); | |
170 | ||
171 | mutex_lock(&inode->i_mutex); | |
172 | inode->i_private = entry; | |
173 | i_size_write(inode, size + sizeof(entry->var.Attributes)); | |
174 | mutex_unlock(&inode->i_mutex); | |
175 | d_add(dentry, inode); | |
176 | ||
177 | return 0; | |
178 | ||
179 | fail_inode: | |
180 | iput(inode); | |
181 | fail_name: | |
182 | kfree(name); | |
183 | fail: | |
184 | kfree(entry); | |
185 | return err; | |
186 | } | |
187 | ||
188 | static int efivarfs_destroy(struct efivar_entry *entry, void *data) | |
189 | { | |
190 | efivar_entry_remove(entry); | |
191 | kfree(entry); | |
192 | return 0; | |
193 | } | |
194 | ||
195 | static int efivarfs_fill_super(struct super_block *sb, void *data, int silent) | |
196 | { | |
197 | struct inode *inode = NULL; | |
198 | struct dentry *root; | |
199 | int err; | |
200 | ||
201 | efivarfs_sb = sb; | |
202 | ||
203 | sb->s_maxbytes = MAX_LFS_FILESIZE; | |
204 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
205 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
206 | sb->s_magic = EFIVARFS_MAGIC; | |
207 | sb->s_op = &efivarfs_ops; | |
208 | sb->s_d_op = &efivarfs_d_ops; | |
209 | sb->s_time_gran = 1; | |
210 | ||
211 | inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, 0); | |
212 | if (!inode) | |
213 | return -ENOMEM; | |
214 | inode->i_op = &efivarfs_dir_inode_operations; | |
215 | ||
216 | root = d_make_root(inode); | |
217 | sb->s_root = root; | |
218 | if (!root) | |
219 | return -ENOMEM; | |
220 | ||
221 | INIT_LIST_HEAD(&efivarfs_list); | |
222 | ||
223 | err = efivar_init(efivarfs_callback, (void *)sb, false, | |
224 | true, &efivarfs_list); | |
225 | if (err) | |
226 | __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL); | |
227 | ||
228 | return err; | |
229 | } | |
230 | ||
231 | static struct dentry *efivarfs_mount(struct file_system_type *fs_type, | |
232 | int flags, const char *dev_name, void *data) | |
233 | { | |
234 | return mount_single(fs_type, flags, data, efivarfs_fill_super); | |
235 | } | |
236 | ||
237 | static void efivarfs_kill_sb(struct super_block *sb) | |
238 | { | |
239 | kill_litter_super(sb); | |
240 | efivarfs_sb = NULL; | |
241 | ||
242 | /* Remove all entries and destroy */ | |
243 | __efivar_entry_iter(efivarfs_destroy, &efivarfs_list, NULL, NULL); | |
244 | } | |
245 | ||
246 | static struct file_system_type efivarfs_type = { | |
247 | .name = "efivarfs", | |
248 | .mount = efivarfs_mount, | |
249 | .kill_sb = efivarfs_kill_sb, | |
250 | }; | |
251 | ||
252 | static __init int efivarfs_init(void) | |
253 | { | |
254 | if (!efi_enabled(EFI_RUNTIME_SERVICES)) | |
255 | return 0; | |
256 | ||
257 | if (!efivars_kobject()) | |
258 | return 0; | |
259 | ||
260 | return register_filesystem(&efivarfs_type); | |
261 | } | |
262 | ||
263 | MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr"); | |
264 | MODULE_DESCRIPTION("EFI Variable Filesystem"); | |
265 | MODULE_LICENSE("GPL"); | |
266 | MODULE_ALIAS_FS("efivarfs"); | |
267 | ||
268 | module_init(efivarfs_init); |