1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Copyright (C) 2012 Red Hat, Inc. |
4 | * Copyright (C) 2012 Jeremy Kerr <jeremy.kerr@canonical.com> |
5 | */ |
6 | |
7 | #include <linux/ctype.h> |
8 | #include <linux/efi.h> |
9 | #include <linux/fs.h> |
10 | #include <linux/fs_context.h> |
11 | #include <linux/fs_parser.h> |
12 | #include <linux/module.h> |
13 | #include <linux/pagemap.h> |
14 | #include <linux/ucs2_string.h> |
15 | #include <linux/slab.h> |
16 | #include <linux/magic.h> |
17 | #include <linux/statfs.h> |
18 | #include <linux/notifier.h> |
19 | #include <linux/printk.h> |
20 | |
21 | #include "internal.h" |
22 | |
23 | static int efivarfs_ops_notifier(struct notifier_block *nb, unsigned long event, |
24 | void *data) |
25 | { |
26 | struct efivarfs_fs_info *sfi = container_of(nb, struct efivarfs_fs_info, nb); |
27 | |
28 | switch (event) { |
29 | case EFIVAR_OPS_RDONLY: |
30 | sfi->sb->s_flags |= SB_RDONLY; |
31 | break; |
32 | case EFIVAR_OPS_RDWR: |
33 | sfi->sb->s_flags &= ~SB_RDONLY; |
34 | break; |
35 | default: |
36 | return NOTIFY_DONE; |
37 | } |
38 | |
39 | return NOTIFY_OK; |
40 | } |
41 | |
42 | static void efivarfs_evict_inode(struct inode *inode) |
43 | { |
44 | clear_inode(inode); |
45 | } |
46 | |
47 | static int efivarfs_show_options(struct seq_file *m, struct dentry *root) |
48 | { |
49 | struct super_block *sb = root->d_sb; |
50 | struct efivarfs_fs_info *sbi = sb->s_fs_info; |
51 | struct efivarfs_mount_opts *opts = &sbi->mount_opts; |
52 | |
53 | if (!uid_eq(left: opts->uid, GLOBAL_ROOT_UID)) |
54 | seq_printf(m, ",uid=%u" , |
55 | from_kuid_munged(&init_user_ns, opts->uid)); |
56 | if (!gid_eq(opts->gid, GLOBAL_ROOT_GID)) |
57 | seq_printf(m, ",gid=%u" , |
58 | from_kgid_munged(&init_user_ns, opts->gid)); |
59 | return 0; |
60 | } |
61 | |
62 | static int efivarfs_statfs(struct dentry *dentry, struct kstatfs *buf) |
63 | { |
64 | const u32 attr = EFI_VARIABLE_NON_VOLATILE | |
65 | EFI_VARIABLE_BOOTSERVICE_ACCESS | |
66 | EFI_VARIABLE_RUNTIME_ACCESS; |
67 | u64 storage_space, remaining_space, max_variable_size; |
68 | u64 id = huge_encode_dev(dev: dentry->d_sb->s_dev); |
69 | efi_status_t status; |
70 | |
71 | /* Some UEFI firmware does not implement QueryVariableInfo() */ |
72 | storage_space = remaining_space = 0; |
73 | if (efi_rt_services_supported(EFI_RT_SUPPORTED_QUERY_VARIABLE_INFO)) { |
74 | status = efivar_query_variable_info(attr, storage_space: &storage_space, |
75 | remaining_space: &remaining_space, |
76 | max_variable_size: &max_variable_size); |
77 | if (status != EFI_SUCCESS && status != EFI_UNSUPPORTED) |
78 | pr_warn_ratelimited("query_variable_info() failed: 0x%lx\n" , |
79 | status); |
80 | } |
81 | |
82 | /* |
83 | * This is not a normal filesystem, so no point in pretending it has a block |
84 | * size; we declare f_bsize to 1, so that we can then report the exact value |
85 | * sent by EFI QueryVariableInfo in f_blocks and f_bfree |
86 | */ |
87 | buf->f_bsize = 1; |
88 | buf->f_namelen = NAME_MAX; |
89 | buf->f_blocks = storage_space; |
90 | buf->f_bfree = remaining_space; |
91 | buf->f_type = dentry->d_sb->s_magic; |
92 | buf->f_fsid = u64_to_fsid(v: id); |
93 | |
94 | /* |
95 | * In f_bavail we declare the free space that the kernel will allow writing |
96 | * when the storage_paranoia x86 quirk is active. To use more, users |
97 | * should boot the kernel with efi_no_storage_paranoia. |
98 | */ |
99 | if (remaining_space > efivar_reserved_space()) |
100 | buf->f_bavail = remaining_space - efivar_reserved_space(); |
101 | else |
102 | buf->f_bavail = 0; |
103 | |
104 | return 0; |
105 | } |
106 | static const struct super_operations efivarfs_ops = { |
107 | .statfs = efivarfs_statfs, |
108 | .drop_inode = generic_delete_inode, |
109 | .evict_inode = efivarfs_evict_inode, |
110 | .show_options = efivarfs_show_options, |
111 | }; |
112 | |
113 | /* |
114 | * Compare two efivarfs file names. |
115 | * |
116 | * An efivarfs filename is composed of two parts, |
117 | * |
118 | * 1. A case-sensitive variable name |
119 | * 2. A case-insensitive GUID |
120 | * |
121 | * So we need to perform a case-sensitive match on part 1 and a |
122 | * case-insensitive match on part 2. |
123 | */ |
124 | static int efivarfs_d_compare(const struct dentry *dentry, |
125 | unsigned int len, const char *str, |
126 | const struct qstr *name) |
127 | { |
128 | int guid = len - EFI_VARIABLE_GUID_LEN; |
129 | |
130 | if (name->len != len) |
131 | return 1; |
132 | |
133 | /* Case-sensitive compare for the variable name */ |
134 | if (memcmp(p: str, q: name->name, size: guid)) |
135 | return 1; |
136 | |
137 | /* Case-insensitive compare for the GUID */ |
138 | return strncasecmp(s1: name->name + guid, s2: str + guid, EFI_VARIABLE_GUID_LEN); |
139 | } |
140 | |
141 | static int efivarfs_d_hash(const struct dentry *dentry, struct qstr *qstr) |
142 | { |
143 | unsigned long hash = init_name_hash(dentry); |
144 | const unsigned char *s = qstr->name; |
145 | unsigned int len = qstr->len; |
146 | |
147 | if (!efivarfs_valid_name(str: s, len)) |
148 | return -EINVAL; |
149 | |
150 | while (len-- > EFI_VARIABLE_GUID_LEN) |
151 | hash = partial_name_hash(c: *s++, prevhash: hash); |
152 | |
153 | /* GUID is case-insensitive. */ |
154 | while (len--) |
155 | hash = partial_name_hash(tolower(*s++), prevhash: hash); |
156 | |
157 | qstr->hash = end_name_hash(hash); |
158 | return 0; |
159 | } |
160 | |
161 | static const struct dentry_operations efivarfs_d_ops = { |
162 | .d_compare = efivarfs_d_compare, |
163 | .d_hash = efivarfs_d_hash, |
164 | .d_delete = always_delete_dentry, |
165 | }; |
166 | |
167 | static struct dentry *efivarfs_alloc_dentry(struct dentry *parent, char *name) |
168 | { |
169 | struct dentry *d; |
170 | struct qstr q; |
171 | int err; |
172 | |
173 | q.name = name; |
174 | q.len = strlen(name); |
175 | |
176 | err = efivarfs_d_hash(dentry: parent, qstr: &q); |
177 | if (err) |
178 | return ERR_PTR(error: err); |
179 | |
180 | d = d_alloc(parent, &q); |
181 | if (d) |
182 | return d; |
183 | |
184 | return ERR_PTR(error: -ENOMEM); |
185 | } |
186 | |
187 | static int efivarfs_callback(efi_char16_t *name16, efi_guid_t vendor, |
188 | unsigned long name_size, void *data, |
189 | struct list_head *list) |
190 | { |
191 | struct super_block *sb = (struct super_block *)data; |
192 | struct efivar_entry *entry; |
193 | struct inode *inode = NULL; |
194 | struct dentry *dentry, *root = sb->s_root; |
195 | unsigned long size = 0; |
196 | char *name; |
197 | int len; |
198 | int err = -ENOMEM; |
199 | bool is_removable = false; |
200 | |
201 | if (guid_equal(u1: &vendor, u2: &LINUX_EFI_RANDOM_SEED_TABLE_GUID)) |
202 | return 0; |
203 | |
204 | entry = kzalloc(size: sizeof(*entry), GFP_KERNEL); |
205 | if (!entry) |
206 | return err; |
207 | |
208 | memcpy(entry->var.VariableName, name16, name_size); |
209 | memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t)); |
210 | |
211 | len = ucs2_utf8size(src: entry->var.VariableName); |
212 | |
213 | /* name, plus '-', plus GUID, plus NUL*/ |
214 | name = kmalloc(size: len + 1 + EFI_VARIABLE_GUID_LEN + 1, GFP_KERNEL); |
215 | if (!name) |
216 | goto fail; |
217 | |
218 | ucs2_as_utf8(dest: name, src: entry->var.VariableName, maxlength: len); |
219 | |
220 | if (efivar_variable_is_removable(vendor: entry->var.VendorGuid, name, len)) |
221 | is_removable = true; |
222 | |
223 | name[len] = '-'; |
224 | |
225 | efi_guid_to_str(guid: &entry->var.VendorGuid, out: name + len + 1); |
226 | |
227 | name[len + EFI_VARIABLE_GUID_LEN+1] = '\0'; |
228 | |
229 | /* replace invalid slashes like kobject_set_name_vargs does for /sys/firmware/efi/vars. */ |
230 | strreplace(str: name, old: '/', new: '!'); |
231 | |
232 | inode = efivarfs_get_inode(sb, dir: d_inode(dentry: root), S_IFREG | 0644, dev: 0, |
233 | is_removable); |
234 | if (!inode) |
235 | goto fail_name; |
236 | |
237 | dentry = efivarfs_alloc_dentry(parent: root, name); |
238 | if (IS_ERR(ptr: dentry)) { |
239 | err = PTR_ERR(ptr: dentry); |
240 | goto fail_inode; |
241 | } |
242 | |
243 | __efivar_entry_get(entry, NULL, size: &size, NULL); |
244 | __efivar_entry_add(entry, head: list); |
245 | |
246 | /* copied by the above to local storage in the dentry. */ |
247 | kfree(objp: name); |
248 | |
249 | inode_lock(inode); |
250 | inode->i_private = entry; |
251 | i_size_write(inode, i_size: size + sizeof(entry->var.Attributes)); |
252 | inode_unlock(inode); |
253 | d_add(dentry, inode); |
254 | |
255 | return 0; |
256 | |
257 | fail_inode: |
258 | iput(inode); |
259 | fail_name: |
260 | kfree(objp: name); |
261 | fail: |
262 | kfree(objp: entry); |
263 | return err; |
264 | } |
265 | |
266 | static int efivarfs_destroy(struct efivar_entry *entry, void *data) |
267 | { |
268 | efivar_entry_remove(entry); |
269 | kfree(objp: entry); |
270 | return 0; |
271 | } |
272 | |
273 | enum { |
274 | Opt_uid, Opt_gid, |
275 | }; |
276 | |
277 | static const struct fs_parameter_spec efivarfs_parameters[] = { |
278 | fsparam_u32("uid" , Opt_uid), |
279 | fsparam_u32("gid" , Opt_gid), |
280 | {}, |
281 | }; |
282 | |
283 | static int efivarfs_parse_param(struct fs_context *fc, struct fs_parameter *param) |
284 | { |
285 | struct efivarfs_fs_info *sbi = fc->s_fs_info; |
286 | struct efivarfs_mount_opts *opts = &sbi->mount_opts; |
287 | struct fs_parse_result result; |
288 | int opt; |
289 | |
290 | opt = fs_parse(fc, desc: efivarfs_parameters, param, result: &result); |
291 | if (opt < 0) |
292 | return opt; |
293 | |
294 | switch (opt) { |
295 | case Opt_uid: |
296 | opts->uid = make_kuid(current_user_ns(), uid: result.uint_32); |
297 | if (!uid_valid(uid: opts->uid)) |
298 | return -EINVAL; |
299 | break; |
300 | case Opt_gid: |
301 | opts->gid = make_kgid(current_user_ns(), gid: result.uint_32); |
302 | if (!gid_valid(gid: opts->gid)) |
303 | return -EINVAL; |
304 | break; |
305 | default: |
306 | return -EINVAL; |
307 | } |
308 | |
309 | return 0; |
310 | } |
311 | |
312 | static int efivarfs_fill_super(struct super_block *sb, struct fs_context *fc) |
313 | { |
314 | struct efivarfs_fs_info *sfi = sb->s_fs_info; |
315 | struct inode *inode = NULL; |
316 | struct dentry *root; |
317 | int err; |
318 | |
319 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
320 | sb->s_blocksize = PAGE_SIZE; |
321 | sb->s_blocksize_bits = PAGE_SHIFT; |
322 | sb->s_magic = EFIVARFS_MAGIC; |
323 | sb->s_op = &efivarfs_ops; |
324 | sb->s_d_op = &efivarfs_d_ops; |
325 | sb->s_time_gran = 1; |
326 | |
327 | if (!efivar_supports_writes()) |
328 | sb->s_flags |= SB_RDONLY; |
329 | |
330 | inode = efivarfs_get_inode(sb, NULL, S_IFDIR | 0755, dev: 0, is_removable: true); |
331 | if (!inode) |
332 | return -ENOMEM; |
333 | inode->i_op = &efivarfs_dir_inode_operations; |
334 | |
335 | root = d_make_root(inode); |
336 | sb->s_root = root; |
337 | if (!root) |
338 | return -ENOMEM; |
339 | |
340 | sfi->sb = sb; |
341 | sfi->nb.notifier_call = efivarfs_ops_notifier; |
342 | err = blocking_notifier_chain_register(nh: &efivar_ops_nh, nb: &sfi->nb); |
343 | if (err) |
344 | return err; |
345 | |
346 | return efivar_init(func: efivarfs_callback, data: sb, head: &sfi->efivarfs_list); |
347 | } |
348 | |
349 | static int efivarfs_get_tree(struct fs_context *fc) |
350 | { |
351 | return get_tree_single(fc, fill_super: efivarfs_fill_super); |
352 | } |
353 | |
354 | static int efivarfs_reconfigure(struct fs_context *fc) |
355 | { |
356 | if (!efivar_supports_writes() && !(fc->sb_flags & SB_RDONLY)) { |
357 | pr_err("Firmware does not support SetVariableRT. Can not remount with rw\n" ); |
358 | return -EINVAL; |
359 | } |
360 | |
361 | return 0; |
362 | } |
363 | |
364 | static const struct fs_context_operations efivarfs_context_ops = { |
365 | .get_tree = efivarfs_get_tree, |
366 | .parse_param = efivarfs_parse_param, |
367 | .reconfigure = efivarfs_reconfigure, |
368 | }; |
369 | |
370 | static int efivarfs_init_fs_context(struct fs_context *fc) |
371 | { |
372 | struct efivarfs_fs_info *sfi; |
373 | |
374 | if (!efivar_is_available()) |
375 | return -EOPNOTSUPP; |
376 | |
377 | sfi = kzalloc(size: sizeof(*sfi), GFP_KERNEL); |
378 | if (!sfi) |
379 | return -ENOMEM; |
380 | |
381 | INIT_LIST_HEAD(list: &sfi->efivarfs_list); |
382 | |
383 | sfi->mount_opts.uid = GLOBAL_ROOT_UID; |
384 | sfi->mount_opts.gid = GLOBAL_ROOT_GID; |
385 | |
386 | fc->s_fs_info = sfi; |
387 | fc->ops = &efivarfs_context_ops; |
388 | return 0; |
389 | } |
390 | |
391 | static void efivarfs_kill_sb(struct super_block *sb) |
392 | { |
393 | struct efivarfs_fs_info *sfi = sb->s_fs_info; |
394 | |
395 | blocking_notifier_chain_unregister(nh: &efivar_ops_nh, nb: &sfi->nb); |
396 | kill_litter_super(sb); |
397 | |
398 | /* Remove all entries and destroy */ |
399 | efivar_entry_iter(func: efivarfs_destroy, head: &sfi->efivarfs_list, NULL); |
400 | kfree(objp: sfi); |
401 | } |
402 | |
403 | static struct file_system_type efivarfs_type = { |
404 | .owner = THIS_MODULE, |
405 | .name = "efivarfs" , |
406 | .init_fs_context = efivarfs_init_fs_context, |
407 | .kill_sb = efivarfs_kill_sb, |
408 | .parameters = efivarfs_parameters, |
409 | }; |
410 | |
411 | static __init int efivarfs_init(void) |
412 | { |
413 | return register_filesystem(&efivarfs_type); |
414 | } |
415 | |
416 | static __exit void efivarfs_exit(void) |
417 | { |
418 | unregister_filesystem(&efivarfs_type); |
419 | } |
420 | |
421 | MODULE_AUTHOR("Matthew Garrett, Jeremy Kerr" ); |
422 | MODULE_DESCRIPTION("EFI Variable Filesystem" ); |
423 | MODULE_LICENSE("GPL" ); |
424 | MODULE_ALIAS_FS("efivarfs" ); |
425 | |
426 | module_init(efivarfs_init); |
427 | module_exit(efivarfs_exit); |
428 | |