1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* |
3 | * Originally from efivars.c |
4 | * |
5 | * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com> |
6 | * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com> |
7 | */ |
8 | |
9 | #include <linux/capability.h> |
10 | #include <linux/types.h> |
11 | #include <linux/errno.h> |
12 | #include <linux/init.h> |
13 | #include <linux/mm.h> |
14 | #include <linux/module.h> |
15 | #include <linux/string.h> |
16 | #include <linux/smp.h> |
17 | #include <linux/efi.h> |
18 | #include <linux/device.h> |
19 | #include <linux/slab.h> |
20 | #include <linux/ctype.h> |
21 | #include <linux/ucs2_string.h> |
22 | |
23 | #include "internal.h" |
24 | |
25 | MODULE_IMPORT_NS(EFIVAR); |
26 | |
27 | static bool |
28 | validate_device_path(efi_char16_t *var_name, int match, u8 *buffer, |
29 | unsigned long len) |
30 | { |
31 | struct efi_generic_dev_path *node; |
32 | int offset = 0; |
33 | |
34 | node = (struct efi_generic_dev_path *)buffer; |
35 | |
36 | if (len < sizeof(*node)) |
37 | return false; |
38 | |
39 | while (offset <= len - sizeof(*node) && |
40 | node->length >= sizeof(*node) && |
41 | node->length <= len - offset) { |
42 | offset += node->length; |
43 | |
44 | if ((node->type == EFI_DEV_END_PATH || |
45 | node->type == EFI_DEV_END_PATH2) && |
46 | node->sub_type == EFI_DEV_END_ENTIRE) |
47 | return true; |
48 | |
49 | node = (struct efi_generic_dev_path *)(buffer + offset); |
50 | } |
51 | |
52 | /* |
53 | * If we're here then either node->length pointed past the end |
54 | * of the buffer or we reached the end of the buffer without |
55 | * finding a device path end node. |
56 | */ |
57 | return false; |
58 | } |
59 | |
60 | static bool |
61 | validate_boot_order(efi_char16_t *var_name, int match, u8 *buffer, |
62 | unsigned long len) |
63 | { |
64 | /* An array of 16-bit integers */ |
65 | if ((len % 2) != 0) |
66 | return false; |
67 | |
68 | return true; |
69 | } |
70 | |
71 | static bool |
72 | validate_load_option(efi_char16_t *var_name, int match, u8 *buffer, |
73 | unsigned long len) |
74 | { |
75 | u16 filepathlength; |
76 | int i, desclength = 0, namelen; |
77 | |
78 | namelen = ucs2_strnlen(s: var_name, EFI_VAR_NAME_LEN); |
79 | |
80 | /* Either "Boot" or "Driver" followed by four digits of hex */ |
81 | for (i = match; i < match+4; i++) { |
82 | if (var_name[i] > 127 || |
83 | hex_to_bin(ch: var_name[i] & 0xff) < 0) |
84 | return true; |
85 | } |
86 | |
87 | /* Reject it if there's 4 digits of hex and then further content */ |
88 | if (namelen > match + 4) |
89 | return false; |
90 | |
91 | /* A valid entry must be at least 8 bytes */ |
92 | if (len < 8) |
93 | return false; |
94 | |
95 | filepathlength = buffer[4] | buffer[5] << 8; |
96 | |
97 | /* |
98 | * There's no stored length for the description, so it has to be |
99 | * found by hand |
100 | */ |
101 | desclength = ucs2_strsize(data: (efi_char16_t *)(buffer + 6), maxlength: len - 6) + 2; |
102 | |
103 | /* Each boot entry must have a descriptor */ |
104 | if (!desclength) |
105 | return false; |
106 | |
107 | /* |
108 | * If the sum of the length of the description, the claimed filepath |
109 | * length and the original header are greater than the length of the |
110 | * variable, it's malformed |
111 | */ |
112 | if ((desclength + filepathlength + 6) > len) |
113 | return false; |
114 | |
115 | /* |
116 | * And, finally, check the filepath |
117 | */ |
118 | return validate_device_path(var_name, match, buffer: buffer + desclength + 6, |
119 | len: filepathlength); |
120 | } |
121 | |
122 | static bool |
123 | validate_uint16(efi_char16_t *var_name, int match, u8 *buffer, |
124 | unsigned long len) |
125 | { |
126 | /* A single 16-bit integer */ |
127 | if (len != 2) |
128 | return false; |
129 | |
130 | return true; |
131 | } |
132 | |
133 | static bool |
134 | validate_ascii_string(efi_char16_t *var_name, int match, u8 *buffer, |
135 | unsigned long len) |
136 | { |
137 | int i; |
138 | |
139 | for (i = 0; i < len; i++) { |
140 | if (buffer[i] > 127) |
141 | return false; |
142 | |
143 | if (buffer[i] == 0) |
144 | return true; |
145 | } |
146 | |
147 | return false; |
148 | } |
149 | |
150 | struct variable_validate { |
151 | efi_guid_t vendor; |
152 | char *name; |
153 | bool (*validate)(efi_char16_t *var_name, int match, u8 *data, |
154 | unsigned long len); |
155 | }; |
156 | |
157 | /* |
158 | * This is the list of variables we need to validate, as well as the |
159 | * whitelist for what we think is safe not to default to immutable. |
160 | * |
161 | * If it has a validate() method that's not NULL, it'll go into the |
162 | * validation routine. If not, it is assumed valid, but still used for |
163 | * whitelisting. |
164 | * |
165 | * Note that it's sorted by {vendor,name}, but globbed names must come after |
166 | * any other name with the same prefix. |
167 | */ |
168 | static const struct variable_validate variable_validate[] = { |
169 | { EFI_GLOBAL_VARIABLE_GUID, "BootNext" , validate_uint16 }, |
170 | { EFI_GLOBAL_VARIABLE_GUID, "BootOrder" , validate_boot_order }, |
171 | { EFI_GLOBAL_VARIABLE_GUID, "Boot*" , validate_load_option }, |
172 | { EFI_GLOBAL_VARIABLE_GUID, "DriverOrder" , validate_boot_order }, |
173 | { EFI_GLOBAL_VARIABLE_GUID, "Driver*" , validate_load_option }, |
174 | { EFI_GLOBAL_VARIABLE_GUID, "ConIn" , validate_device_path }, |
175 | { EFI_GLOBAL_VARIABLE_GUID, "ConInDev" , validate_device_path }, |
176 | { EFI_GLOBAL_VARIABLE_GUID, "ConOut" , validate_device_path }, |
177 | { EFI_GLOBAL_VARIABLE_GUID, "ConOutDev" , validate_device_path }, |
178 | { EFI_GLOBAL_VARIABLE_GUID, "ErrOut" , validate_device_path }, |
179 | { EFI_GLOBAL_VARIABLE_GUID, "ErrOutDev" , validate_device_path }, |
180 | { EFI_GLOBAL_VARIABLE_GUID, "Lang" , validate_ascii_string }, |
181 | { EFI_GLOBAL_VARIABLE_GUID, "OsIndications" , NULL }, |
182 | { EFI_GLOBAL_VARIABLE_GUID, "PlatformLang" , validate_ascii_string }, |
183 | { EFI_GLOBAL_VARIABLE_GUID, "Timeout" , validate_uint16 }, |
184 | { LINUX_EFI_CRASH_GUID, "*" , NULL }, |
185 | { NULL_GUID, "" , NULL }, |
186 | }; |
187 | |
188 | /* |
189 | * Check if @var_name matches the pattern given in @match_name. |
190 | * |
191 | * @var_name: an array of @len non-NUL characters. |
192 | * @match_name: a NUL-terminated pattern string, optionally ending in "*". A |
193 | * final "*" character matches any trailing characters @var_name, |
194 | * including the case when there are none left in @var_name. |
195 | * @match: on output, the number of non-wildcard characters in @match_name |
196 | * that @var_name matches, regardless of the return value. |
197 | * @return: whether @var_name fully matches @match_name. |
198 | */ |
199 | static bool |
200 | variable_matches(const char *var_name, size_t len, const char *match_name, |
201 | int *match) |
202 | { |
203 | for (*match = 0; ; (*match)++) { |
204 | char c = match_name[*match]; |
205 | |
206 | switch (c) { |
207 | case '*': |
208 | /* Wildcard in @match_name means we've matched. */ |
209 | return true; |
210 | |
211 | case '\0': |
212 | /* @match_name has ended. Has @var_name too? */ |
213 | return (*match == len); |
214 | |
215 | default: |
216 | /* |
217 | * We've reached a non-wildcard char in @match_name. |
218 | * Continue only if there's an identical character in |
219 | * @var_name. |
220 | */ |
221 | if (*match < len && c == var_name[*match]) |
222 | continue; |
223 | return false; |
224 | } |
225 | } |
226 | } |
227 | |
228 | bool |
229 | efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data, |
230 | unsigned long data_size) |
231 | { |
232 | int i; |
233 | unsigned long utf8_size; |
234 | u8 *utf8_name; |
235 | |
236 | utf8_size = ucs2_utf8size(src: var_name); |
237 | utf8_name = kmalloc(size: utf8_size + 1, GFP_KERNEL); |
238 | if (!utf8_name) |
239 | return false; |
240 | |
241 | ucs2_as_utf8(dest: utf8_name, src: var_name, maxlength: utf8_size); |
242 | utf8_name[utf8_size] = '\0'; |
243 | |
244 | for (i = 0; variable_validate[i].name[0] != '\0'; i++) { |
245 | const char *name = variable_validate[i].name; |
246 | int match = 0; |
247 | |
248 | if (efi_guidcmp(left: vendor, right: variable_validate[i].vendor)) |
249 | continue; |
250 | |
251 | if (variable_matches(var_name: utf8_name, len: utf8_size+1, match_name: name, match: &match)) { |
252 | if (variable_validate[i].validate == NULL) |
253 | break; |
254 | kfree(objp: utf8_name); |
255 | return variable_validate[i].validate(var_name, match, |
256 | data, data_size); |
257 | } |
258 | } |
259 | kfree(objp: utf8_name); |
260 | return true; |
261 | } |
262 | |
263 | bool |
264 | efivar_variable_is_removable(efi_guid_t vendor, const char *var_name, |
265 | size_t len) |
266 | { |
267 | int i; |
268 | bool found = false; |
269 | int match = 0; |
270 | |
271 | /* |
272 | * Check if our variable is in the validated variables list |
273 | */ |
274 | for (i = 0; variable_validate[i].name[0] != '\0'; i++) { |
275 | if (efi_guidcmp(left: variable_validate[i].vendor, right: vendor)) |
276 | continue; |
277 | |
278 | if (variable_matches(var_name, len, |
279 | match_name: variable_validate[i].name, match: &match)) { |
280 | found = true; |
281 | break; |
282 | } |
283 | } |
284 | |
285 | /* |
286 | * If it's in our list, it is removable. |
287 | */ |
288 | return found; |
289 | } |
290 | |
291 | static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor, |
292 | struct list_head *head) |
293 | { |
294 | struct efivar_entry *entry, *n; |
295 | unsigned long strsize1, strsize2; |
296 | bool found = false; |
297 | |
298 | strsize1 = ucs2_strsize(data: variable_name, maxlength: 1024); |
299 | list_for_each_entry_safe(entry, n, head, list) { |
300 | strsize2 = ucs2_strsize(data: entry->var.VariableName, maxlength: 1024); |
301 | if (strsize1 == strsize2 && |
302 | !memcmp(p: variable_name, q: &(entry->var.VariableName), |
303 | size: strsize2) && |
304 | !efi_guidcmp(left: entry->var.VendorGuid, |
305 | right: *vendor)) { |
306 | found = true; |
307 | break; |
308 | } |
309 | } |
310 | return found; |
311 | } |
312 | |
313 | /* |
314 | * Returns the size of variable_name, in bytes, including the |
315 | * terminating NULL character, or variable_name_size if no NULL |
316 | * character is found among the first variable_name_size bytes. |
317 | */ |
318 | static unsigned long var_name_strnsize(efi_char16_t *variable_name, |
319 | unsigned long variable_name_size) |
320 | { |
321 | unsigned long len; |
322 | efi_char16_t c; |
323 | |
324 | /* |
325 | * The variable name is, by definition, a NULL-terminated |
326 | * string, so make absolutely sure that variable_name_size is |
327 | * the value we expect it to be. If not, return the real size. |
328 | */ |
329 | for (len = 2; len <= variable_name_size; len += sizeof(c)) { |
330 | c = variable_name[(len / sizeof(c)) - 1]; |
331 | if (!c) |
332 | break; |
333 | } |
334 | |
335 | return min(len, variable_name_size); |
336 | } |
337 | |
338 | /* |
339 | * Print a warning when duplicate EFI variables are encountered and |
340 | * disable the sysfs workqueue since the firmware is buggy. |
341 | */ |
342 | static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid, |
343 | unsigned long len16) |
344 | { |
345 | size_t i, len8 = len16 / sizeof(efi_char16_t); |
346 | char *str8; |
347 | |
348 | str8 = kzalloc(size: len8, GFP_KERNEL); |
349 | if (!str8) |
350 | return; |
351 | |
352 | for (i = 0; i < len8; i++) |
353 | str8[i] = str16[i]; |
354 | |
355 | printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n" , |
356 | str8, vendor_guid); |
357 | kfree(objp: str8); |
358 | } |
359 | |
360 | /** |
361 | * efivar_init - build the initial list of EFI variables |
362 | * @func: callback function to invoke for every variable |
363 | * @data: function-specific data to pass to @func |
364 | * @head: initialised head of variable list |
365 | * |
366 | * Get every EFI variable from the firmware and invoke @func. @func |
367 | * should call efivar_entry_add() to build the list of variables. |
368 | * |
369 | * Returns 0 on success, or a kernel error code on failure. |
370 | */ |
371 | int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *, |
372 | struct list_head *), |
373 | void *data, struct list_head *head) |
374 | { |
375 | unsigned long variable_name_size = 512; |
376 | efi_char16_t *variable_name; |
377 | efi_status_t status; |
378 | efi_guid_t vendor_guid; |
379 | int err = 0; |
380 | |
381 | variable_name = kzalloc(size: variable_name_size, GFP_KERNEL); |
382 | if (!variable_name) { |
383 | printk(KERN_ERR "efivars: Memory allocation failed.\n" ); |
384 | return -ENOMEM; |
385 | } |
386 | |
387 | err = efivar_lock(); |
388 | if (err) |
389 | goto free; |
390 | |
391 | /* |
392 | * A small set of old UEFI implementations reject sizes |
393 | * above a certain threshold, the lowest seen in the wild |
394 | * is 512. |
395 | */ |
396 | |
397 | do { |
398 | variable_name_size = 512; |
399 | |
400 | status = efivar_get_next_variable(name_size: &variable_name_size, |
401 | name: variable_name, |
402 | vendor: &vendor_guid); |
403 | switch (status) { |
404 | case EFI_SUCCESS: |
405 | variable_name_size = var_name_strnsize(variable_name, |
406 | variable_name_size); |
407 | |
408 | /* |
409 | * Some firmware implementations return the |
410 | * same variable name on multiple calls to |
411 | * get_next_variable(). Terminate the loop |
412 | * immediately as there is no guarantee that |
413 | * we'll ever see a different variable name, |
414 | * and may end up looping here forever. |
415 | */ |
416 | if (variable_is_present(variable_name, vendor: &vendor_guid, |
417 | head)) { |
418 | dup_variable_bug(str16: variable_name, vendor_guid: &vendor_guid, |
419 | len16: variable_name_size); |
420 | status = EFI_NOT_FOUND; |
421 | } else { |
422 | err = func(variable_name, vendor_guid, |
423 | variable_name_size, data, head); |
424 | if (err) |
425 | status = EFI_NOT_FOUND; |
426 | } |
427 | break; |
428 | case EFI_UNSUPPORTED: |
429 | err = -EOPNOTSUPP; |
430 | status = EFI_NOT_FOUND; |
431 | break; |
432 | case EFI_NOT_FOUND: |
433 | break; |
434 | case EFI_BUFFER_TOO_SMALL: |
435 | pr_warn("efivars: Variable name size exceeds maximum (%lu > 512)\n" , |
436 | variable_name_size); |
437 | status = EFI_NOT_FOUND; |
438 | break; |
439 | default: |
440 | pr_warn("efivars: get_next_variable: status=%lx\n" , status); |
441 | status = EFI_NOT_FOUND; |
442 | break; |
443 | } |
444 | |
445 | } while (status != EFI_NOT_FOUND); |
446 | |
447 | efivar_unlock(); |
448 | free: |
449 | kfree(objp: variable_name); |
450 | |
451 | return err; |
452 | } |
453 | |
454 | /** |
455 | * efivar_entry_add - add entry to variable list |
456 | * @entry: entry to add to list |
457 | * @head: list head |
458 | * |
459 | * Returns 0 on success, or a kernel error code on failure. |
460 | */ |
461 | int efivar_entry_add(struct efivar_entry *entry, struct list_head *head) |
462 | { |
463 | int err; |
464 | |
465 | err = efivar_lock(); |
466 | if (err) |
467 | return err; |
468 | list_add(new: &entry->list, head); |
469 | efivar_unlock(); |
470 | |
471 | return 0; |
472 | } |
473 | |
474 | /** |
475 | * __efivar_entry_add - add entry to variable list |
476 | * @entry: entry to add to list |
477 | * @head: list head |
478 | */ |
479 | void __efivar_entry_add(struct efivar_entry *entry, struct list_head *head) |
480 | { |
481 | list_add(new: &entry->list, head); |
482 | } |
483 | |
484 | /** |
485 | * efivar_entry_remove - remove entry from variable list |
486 | * @entry: entry to remove from list |
487 | * |
488 | * Returns 0 on success, or a kernel error code on failure. |
489 | */ |
490 | void efivar_entry_remove(struct efivar_entry *entry) |
491 | { |
492 | list_del(entry: &entry->list); |
493 | } |
494 | |
495 | /* |
496 | * efivar_entry_list_del_unlock - remove entry from variable list |
497 | * @entry: entry to remove |
498 | * |
499 | * Remove @entry from the variable list and release the list lock. |
500 | * |
501 | * NOTE: slightly weird locking semantics here - we expect to be |
502 | * called with the efivars lock already held, and we release it before |
503 | * returning. This is because this function is usually called after |
504 | * set_variable() while the lock is still held. |
505 | */ |
506 | static void efivar_entry_list_del_unlock(struct efivar_entry *entry) |
507 | { |
508 | list_del(entry: &entry->list); |
509 | efivar_unlock(); |
510 | } |
511 | |
512 | /** |
513 | * efivar_entry_delete - delete variable and remove entry from list |
514 | * @entry: entry containing variable to delete |
515 | * |
516 | * Delete the variable from the firmware and remove @entry from the |
517 | * variable list. It is the caller's responsibility to free @entry |
518 | * once we return. |
519 | * |
520 | * Returns 0 on success, -EINTR if we can't grab the semaphore, |
521 | * converted EFI status code if set_variable() fails. |
522 | */ |
523 | int efivar_entry_delete(struct efivar_entry *entry) |
524 | { |
525 | efi_status_t status; |
526 | int err; |
527 | |
528 | err = efivar_lock(); |
529 | if (err) |
530 | return err; |
531 | |
532 | status = efivar_set_variable_locked(name: entry->var.VariableName, |
533 | vendor: &entry->var.VendorGuid, |
534 | attr: 0, data_size: 0, NULL, nonblocking: false); |
535 | if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND)) { |
536 | efivar_unlock(); |
537 | return efi_status_to_err(status); |
538 | } |
539 | |
540 | efivar_entry_list_del_unlock(entry); |
541 | return 0; |
542 | } |
543 | |
544 | /** |
545 | * efivar_entry_size - obtain the size of a variable |
546 | * @entry: entry for this variable |
547 | * @size: location to store the variable's size |
548 | */ |
549 | int efivar_entry_size(struct efivar_entry *entry, unsigned long *size) |
550 | { |
551 | efi_status_t status; |
552 | int err; |
553 | |
554 | *size = 0; |
555 | |
556 | err = efivar_lock(); |
557 | if (err) |
558 | return err; |
559 | |
560 | status = efivar_get_variable(name: entry->var.VariableName, |
561 | vendor: &entry->var.VendorGuid, NULL, size, NULL); |
562 | efivar_unlock(); |
563 | |
564 | if (status != EFI_BUFFER_TOO_SMALL) |
565 | return efi_status_to_err(status); |
566 | |
567 | return 0; |
568 | } |
569 | |
570 | /** |
571 | * __efivar_entry_get - call get_variable() |
572 | * @entry: read data for this variable |
573 | * @attributes: variable attributes |
574 | * @size: size of @data buffer |
575 | * @data: buffer to store variable data |
576 | * |
577 | * The caller MUST call efivar_entry_iter_begin() and |
578 | * efivar_entry_iter_end() before and after the invocation of this |
579 | * function, respectively. |
580 | */ |
581 | int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes, |
582 | unsigned long *size, void *data) |
583 | { |
584 | efi_status_t status; |
585 | |
586 | status = efivar_get_variable(name: entry->var.VariableName, |
587 | vendor: &entry->var.VendorGuid, |
588 | attr: attributes, size, data); |
589 | |
590 | return efi_status_to_err(status); |
591 | } |
592 | |
593 | /** |
594 | * efivar_entry_get - call get_variable() |
595 | * @entry: read data for this variable |
596 | * @attributes: variable attributes |
597 | * @size: size of @data buffer |
598 | * @data: buffer to store variable data |
599 | */ |
600 | int efivar_entry_get(struct efivar_entry *entry, u32 *attributes, |
601 | unsigned long *size, void *data) |
602 | { |
603 | int err; |
604 | |
605 | err = efivar_lock(); |
606 | if (err) |
607 | return err; |
608 | err = __efivar_entry_get(entry, attributes, size, data); |
609 | efivar_unlock(); |
610 | |
611 | return 0; |
612 | } |
613 | |
614 | /** |
615 | * efivar_entry_set_get_size - call set_variable() and get new size (atomic) |
616 | * @entry: entry containing variable to set and get |
617 | * @attributes: attributes of variable to be written |
618 | * @size: size of data buffer |
619 | * @data: buffer containing data to write |
620 | * @set: did the set_variable() call succeed? |
621 | * |
622 | * This is a pretty special (complex) function. See efivarfs_file_write(). |
623 | * |
624 | * Atomically call set_variable() for @entry and if the call is |
625 | * successful, return the new size of the variable from get_variable() |
626 | * in @size. The success of set_variable() is indicated by @set. |
627 | * |
628 | * Returns 0 on success, -EINVAL if the variable data is invalid, |
629 | * -ENOSPC if the firmware does not have enough available space, or a |
630 | * converted EFI status code if either of set_variable() or |
631 | * get_variable() fail. |
632 | * |
633 | * If the EFI variable does not exist when calling set_variable() |
634 | * (EFI_NOT_FOUND), @entry is removed from the variable list. |
635 | */ |
636 | int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes, |
637 | unsigned long *size, void *data, bool *set) |
638 | { |
639 | efi_char16_t *name = entry->var.VariableName; |
640 | efi_guid_t *vendor = &entry->var.VendorGuid; |
641 | efi_status_t status; |
642 | int err; |
643 | |
644 | *set = false; |
645 | |
646 | if (efivar_validate(vendor: *vendor, var_name: name, data, data_size: *size) == false) |
647 | return -EINVAL; |
648 | |
649 | /* |
650 | * The lock here protects the get_variable call, the conditional |
651 | * set_variable call, and removal of the variable from the efivars |
652 | * list (in the case of an authenticated delete). |
653 | */ |
654 | err = efivar_lock(); |
655 | if (err) |
656 | return err; |
657 | |
658 | status = efivar_set_variable_locked(name, vendor, attr: attributes, data_size: *size, |
659 | data, nonblocking: false); |
660 | if (status != EFI_SUCCESS) { |
661 | err = efi_status_to_err(status); |
662 | goto out; |
663 | } |
664 | |
665 | *set = true; |
666 | |
667 | /* |
668 | * Writing to the variable may have caused a change in size (which |
669 | * could either be an append or an overwrite), or the variable to be |
670 | * deleted. Perform a GetVariable() so we can tell what actually |
671 | * happened. |
672 | */ |
673 | *size = 0; |
674 | status = efivar_get_variable(name: entry->var.VariableName, |
675 | vendor: &entry->var.VendorGuid, |
676 | NULL, size, NULL); |
677 | |
678 | if (status == EFI_NOT_FOUND) |
679 | efivar_entry_list_del_unlock(entry); |
680 | else |
681 | efivar_unlock(); |
682 | |
683 | if (status && status != EFI_BUFFER_TOO_SMALL) |
684 | return efi_status_to_err(status); |
685 | |
686 | return 0; |
687 | |
688 | out: |
689 | efivar_unlock(); |
690 | return err; |
691 | |
692 | } |
693 | |
694 | /** |
695 | * efivar_entry_iter - iterate over variable list |
696 | * @func: callback function |
697 | * @head: head of variable list |
698 | * @data: function-specific data to pass to callback |
699 | * |
700 | * Iterate over the list of EFI variables and call @func with every |
701 | * entry on the list. It is safe for @func to remove entries in the |
702 | * list via efivar_entry_delete() while iterating. |
703 | * |
704 | * Some notes for the callback function: |
705 | * - a non-zero return value indicates an error and terminates the loop |
706 | * - @func is called from atomic context |
707 | */ |
708 | int efivar_entry_iter(int (*func)(struct efivar_entry *, void *), |
709 | struct list_head *head, void *data) |
710 | { |
711 | struct efivar_entry *entry, *n; |
712 | int err = 0; |
713 | |
714 | err = efivar_lock(); |
715 | if (err) |
716 | return err; |
717 | |
718 | list_for_each_entry_safe(entry, n, head, list) { |
719 | err = func(entry, data); |
720 | if (err) |
721 | break; |
722 | } |
723 | efivar_unlock(); |
724 | |
725 | return err; |
726 | } |
727 | |