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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> | |
15 | ||
16 | #include "internal.h" | |
17 | ||
18 | LIST_HEAD(efivarfs_list); | |
19 | ||
20 | static void efivarfs_evict_inode(struct inode *inode) | |
21 | { | |
22 | clear_inode(inode); | |
23 | } | |
24 | ||
25 | static const struct super_operations efivarfs_ops = { | |
26 | .statfs = simple_statfs, | |
27 | .drop_inode = generic_delete_inode, | |
28 | .evict_inode = efivarfs_evict_inode, | |
29 | .show_options = generic_show_options, | |
30 | }; | |
31 | ||
32 | static struct super_block *efivarfs_sb; | |
33 | ||
34 | /* | |
35 | * Compare two efivarfs file names. | |
36 | * | |
37 | * An efivarfs filename is composed of two parts, | |
38 | * | |
39 | * 1. A case-sensitive variable name | |
40 | * 2. A case-insensitive GUID | |
41 | * | |
42 | * So we need to perform a case-sensitive match on part 1 and a | |
43 | * case-insensitive match on part 2. | |
44 | */ | |
45 | static int efivarfs_d_compare(const struct dentry *parent, const struct inode *pinode, | |
46 | const struct dentry *dentry, const struct inode *inode, | |
47 | unsigned int len, const char *str, | |
48 | const struct qstr *name) | |
49 | { | |
50 | int guid = len - EFI_VARIABLE_GUID_LEN; | |
51 | ||
52 | if (name->len != len) | |
53 | return 1; | |
54 | ||
55 | /* Case-sensitive compare for the variable name */ | |
56 | if (memcmp(str, name->name, guid)) | |
57 | return 1; | |
58 | ||
59 | /* Case-insensitive compare for the GUID */ | |
60 | return strncasecmp(name->name + guid, str + guid, EFI_VARIABLE_GUID_LEN); | |
61 | } | |
62 | ||
63 | static int efivarfs_d_hash(const struct dentry *dentry, | |
64 | const struct inode *inode, struct qstr *qstr) | |
65 | { | |
66 | unsigned long hash = init_name_hash(); | |
67 | const unsigned char *s = qstr->name; | |
68 | unsigned int len = qstr->len; | |
69 | ||
70 | if (!efivarfs_valid_name(s, len)) | |
71 | return -EINVAL; | |
72 | ||
73 | while (len-- > EFI_VARIABLE_GUID_LEN) | |
74 | hash = partial_name_hash(*s++, hash); | |
75 | ||
76 | /* GUID is case-insensitive. */ | |
77 | while (len--) | |
78 | hash = partial_name_hash(tolower(*s++), hash); | |
79 | ||
80 | qstr->hash = end_name_hash(hash); | |
81 | return 0; | |
82 | } | |
83 | ||
84 | /* | |
85 | * Retaining negative dentries for an in-memory filesystem just wastes | |
86 | * memory and lookup time: arrange for them to be deleted immediately. | |
87 | */ | |
88 | static int efivarfs_delete_dentry(const struct dentry *dentry) | |
89 | { | |
90 | return 1; | |
91 | } | |
92 | ||
93 | static struct dentry_operations efivarfs_d_ops = { | |
94 | .d_compare = efivarfs_d_compare, | |
95 | .d_hash = efivarfs_d_hash, | |
96 | .d_delete = efivarfs_delete_dentry, | |
97 | }; | |
98 | ||
99 | static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name) | |
100 | { | |
101 | struct dentry *d; | |
102 | struct qstr q; | |
103 | int err; | |
104 | ||
105 | q.name = name; | |
106 | q.len = strlen(name); | |
107 | ||
108 | err = efivarfs_d_hash(NULL, NULL, &q); | |
109 | if (err) | |
110 | return ERR_PTR(err); | |
111 | ||
112 | d = d_alloc(parent, &q); | |
113 | if (d) | |
114 | return d; | |
115 | ||
116 | return ERR_PTR(-ENOMEM); | |
117 | } | |
118 | ||
119 | static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor, | |
120 | unsigned long name_size, void *data) | |
121 | { | |
122 | struct super_block *sb = (struct super_block *)data; | |
123 | struct efivar_entry *entry; | |
124 | struct inode *inode = NULL; | |
125 | struct dentry *dentry, *root = sb->s_root; | |
126 | unsigned long size = 0; | |
127 | char *name; | |
128 | int len, i; | |
129 | int err = -ENOMEM; | |
130 | ||
131 | entry = kmalloc(sizeof(*entry), GFP_KERNEL); | |
132 | if (!entry) | |
133 | return err; | |
134 | ||
135 | memcpy(entry->var.VariableName, name16, name_size); | |
136 | memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t)); | |
137 | ||
138 | len = utf16_strlen(entry->var.VariableName); | |
139 | ||
140 | /* name, plus '-', plus GUID, plus NUL*/ | |
141 | name = kmalloc(len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL); | |
142 | if (!name) | |
143 | goto fail; | |
144 | ||
145 | for (i = 0; i < len; i++) | |
146 | name[i] = entry->var.VariableName[i] & 0xFF; | |
147 | ||
148 | name[len] = '-'; | |
149 | ||
150 | efi_guid_unparse(&entry->var.VendorGuid, name + len + 1); | |
151 | ||
152 | name[len + EFI_VARIABLE_GUID_LEN+1] = '\0'; | |
153 | ||
154 | inode = efivarfs_get_inode(sb, root->d_inode, S_IFREG | 0644, 0); | |
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 | ||
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 | ||
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); | |
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 | ||
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 | ||
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 | .name = "efivarfs", | |
247 | .mount = efivarfs_mount, | |
248 | .kill_sb = efivarfs_kill_sb, | |
249 | }; | |
250 | ||
251 | static __init int efivarfs_init(void) | |
252 | { | |
253 | if (!efi_enabled(EFI_RUNTIME_SERVICES)) | |
254 | return 0; | |
255 | ||
256 | if (!efivars_kobject()) | |
257 | return 0; | |
258 | ||
259 | return register_filesystem(&efivarfs_type); | |
260 | } | |
261 | ||
262 | MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr"); | |
263 | MODULE_DESCRIPTION("EFI Variable Filesystem"); | |
264 | MODULE_LICENSE("GPL"); | |
265 | MODULE_ALIAS_FS("efivarfs"); | |
266 | ||
267 | module_init(efivarfs_init); |