Merge tag 'md/4.6-rc6-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/shli/md
[deliverable/linux.git] / drivers / firmware / efi / vars.c
1 /*
2 * Originally from efivars.c
3 *
4 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
5 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 */
21
22 #include <linux/capability.h>
23 #include <linux/types.h>
24 #include <linux/errno.h>
25 #include <linux/init.h>
26 #include <linux/mm.h>
27 #include <linux/module.h>
28 #include <linux/string.h>
29 #include <linux/smp.h>
30 #include <linux/efi.h>
31 #include <linux/sysfs.h>
32 #include <linux/device.h>
33 #include <linux/slab.h>
34 #include <linux/ctype.h>
35 #include <linux/ucs2_string.h>
36
37 /* Private pointer to registered efivars */
38 static struct efivars *__efivars;
39
40 static bool efivar_wq_enabled = true;
41 DECLARE_WORK(efivar_work, NULL);
42 EXPORT_SYMBOL_GPL(efivar_work);
43
44 static bool
45 validate_device_path(efi_char16_t *var_name, int match, u8 *buffer,
46 unsigned long len)
47 {
48 struct efi_generic_dev_path *node;
49 int offset = 0;
50
51 node = (struct efi_generic_dev_path *)buffer;
52
53 if (len < sizeof(*node))
54 return false;
55
56 while (offset <= len - sizeof(*node) &&
57 node->length >= sizeof(*node) &&
58 node->length <= len - offset) {
59 offset += node->length;
60
61 if ((node->type == EFI_DEV_END_PATH ||
62 node->type == EFI_DEV_END_PATH2) &&
63 node->sub_type == EFI_DEV_END_ENTIRE)
64 return true;
65
66 node = (struct efi_generic_dev_path *)(buffer + offset);
67 }
68
69 /*
70 * If we're here then either node->length pointed past the end
71 * of the buffer or we reached the end of the buffer without
72 * finding a device path end node.
73 */
74 return false;
75 }
76
77 static bool
78 validate_boot_order(efi_char16_t *var_name, int match, u8 *buffer,
79 unsigned long len)
80 {
81 /* An array of 16-bit integers */
82 if ((len % 2) != 0)
83 return false;
84
85 return true;
86 }
87
88 static bool
89 validate_load_option(efi_char16_t *var_name, int match, u8 *buffer,
90 unsigned long len)
91 {
92 u16 filepathlength;
93 int i, desclength = 0, namelen;
94
95 namelen = ucs2_strnlen(var_name, EFI_VAR_NAME_LEN);
96
97 /* Either "Boot" or "Driver" followed by four digits of hex */
98 for (i = match; i < match+4; i++) {
99 if (var_name[i] > 127 ||
100 hex_to_bin(var_name[i] & 0xff) < 0)
101 return true;
102 }
103
104 /* Reject it if there's 4 digits of hex and then further content */
105 if (namelen > match + 4)
106 return false;
107
108 /* A valid entry must be at least 8 bytes */
109 if (len < 8)
110 return false;
111
112 filepathlength = buffer[4] | buffer[5] << 8;
113
114 /*
115 * There's no stored length for the description, so it has to be
116 * found by hand
117 */
118 desclength = ucs2_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2;
119
120 /* Each boot entry must have a descriptor */
121 if (!desclength)
122 return false;
123
124 /*
125 * If the sum of the length of the description, the claimed filepath
126 * length and the original header are greater than the length of the
127 * variable, it's malformed
128 */
129 if ((desclength + filepathlength + 6) > len)
130 return false;
131
132 /*
133 * And, finally, check the filepath
134 */
135 return validate_device_path(var_name, match, buffer + desclength + 6,
136 filepathlength);
137 }
138
139 static bool
140 validate_uint16(efi_char16_t *var_name, int match, u8 *buffer,
141 unsigned long len)
142 {
143 /* A single 16-bit integer */
144 if (len != 2)
145 return false;
146
147 return true;
148 }
149
150 static bool
151 validate_ascii_string(efi_char16_t *var_name, int match, u8 *buffer,
152 unsigned long len)
153 {
154 int i;
155
156 for (i = 0; i < len; i++) {
157 if (buffer[i] > 127)
158 return false;
159
160 if (buffer[i] == 0)
161 return true;
162 }
163
164 return false;
165 }
166
167 struct variable_validate {
168 efi_guid_t vendor;
169 char *name;
170 bool (*validate)(efi_char16_t *var_name, int match, u8 *data,
171 unsigned long len);
172 };
173
174 /*
175 * This is the list of variables we need to validate, as well as the
176 * whitelist for what we think is safe not to default to immutable.
177 *
178 * If it has a validate() method that's not NULL, it'll go into the
179 * validation routine. If not, it is assumed valid, but still used for
180 * whitelisting.
181 *
182 * Note that it's sorted by {vendor,name}, but globbed names must come after
183 * any other name with the same prefix.
184 */
185 static const struct variable_validate variable_validate[] = {
186 { EFI_GLOBAL_VARIABLE_GUID, "BootNext", validate_uint16 },
187 { EFI_GLOBAL_VARIABLE_GUID, "BootOrder", validate_boot_order },
188 { EFI_GLOBAL_VARIABLE_GUID, "Boot*", validate_load_option },
189 { EFI_GLOBAL_VARIABLE_GUID, "DriverOrder", validate_boot_order },
190 { EFI_GLOBAL_VARIABLE_GUID, "Driver*", validate_load_option },
191 { EFI_GLOBAL_VARIABLE_GUID, "ConIn", validate_device_path },
192 { EFI_GLOBAL_VARIABLE_GUID, "ConInDev", validate_device_path },
193 { EFI_GLOBAL_VARIABLE_GUID, "ConOut", validate_device_path },
194 { EFI_GLOBAL_VARIABLE_GUID, "ConOutDev", validate_device_path },
195 { EFI_GLOBAL_VARIABLE_GUID, "ErrOut", validate_device_path },
196 { EFI_GLOBAL_VARIABLE_GUID, "ErrOutDev", validate_device_path },
197 { EFI_GLOBAL_VARIABLE_GUID, "Lang", validate_ascii_string },
198 { EFI_GLOBAL_VARIABLE_GUID, "OsIndications", NULL },
199 { EFI_GLOBAL_VARIABLE_GUID, "PlatformLang", validate_ascii_string },
200 { EFI_GLOBAL_VARIABLE_GUID, "Timeout", validate_uint16 },
201 { LINUX_EFI_CRASH_GUID, "*", NULL },
202 { NULL_GUID, "", NULL },
203 };
204
205 /*
206 * Check if @var_name matches the pattern given in @match_name.
207 *
208 * @var_name: an array of @len non-NUL characters.
209 * @match_name: a NUL-terminated pattern string, optionally ending in "*". A
210 * final "*" character matches any trailing characters @var_name,
211 * including the case when there are none left in @var_name.
212 * @match: on output, the number of non-wildcard characters in @match_name
213 * that @var_name matches, regardless of the return value.
214 * @return: whether @var_name fully matches @match_name.
215 */
216 static bool
217 variable_matches(const char *var_name, size_t len, const char *match_name,
218 int *match)
219 {
220 for (*match = 0; ; (*match)++) {
221 char c = match_name[*match];
222
223 switch (c) {
224 case '*':
225 /* Wildcard in @match_name means we've matched. */
226 return true;
227
228 case '\0':
229 /* @match_name has ended. Has @var_name too? */
230 return (*match == len);
231
232 default:
233 /*
234 * We've reached a non-wildcard char in @match_name.
235 * Continue only if there's an identical character in
236 * @var_name.
237 */
238 if (*match < len && c == var_name[*match])
239 continue;
240 return false;
241 }
242 }
243 }
244
245 bool
246 efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data,
247 unsigned long data_size)
248 {
249 int i;
250 unsigned long utf8_size;
251 u8 *utf8_name;
252
253 utf8_size = ucs2_utf8size(var_name);
254 utf8_name = kmalloc(utf8_size + 1, GFP_KERNEL);
255 if (!utf8_name)
256 return false;
257
258 ucs2_as_utf8(utf8_name, var_name, utf8_size);
259 utf8_name[utf8_size] = '\0';
260
261 for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
262 const char *name = variable_validate[i].name;
263 int match = 0;
264
265 if (efi_guidcmp(vendor, variable_validate[i].vendor))
266 continue;
267
268 if (variable_matches(utf8_name, utf8_size+1, name, &match)) {
269 if (variable_validate[i].validate == NULL)
270 break;
271 kfree(utf8_name);
272 return variable_validate[i].validate(var_name, match,
273 data, data_size);
274 }
275 }
276 kfree(utf8_name);
277 return true;
278 }
279 EXPORT_SYMBOL_GPL(efivar_validate);
280
281 bool
282 efivar_variable_is_removable(efi_guid_t vendor, const char *var_name,
283 size_t len)
284 {
285 int i;
286 bool found = false;
287 int match = 0;
288
289 /*
290 * Check if our variable is in the validated variables list
291 */
292 for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
293 if (efi_guidcmp(variable_validate[i].vendor, vendor))
294 continue;
295
296 if (variable_matches(var_name, len,
297 variable_validate[i].name, &match)) {
298 found = true;
299 break;
300 }
301 }
302
303 /*
304 * If it's in our list, it is removable.
305 */
306 return found;
307 }
308 EXPORT_SYMBOL_GPL(efivar_variable_is_removable);
309
310 static efi_status_t
311 check_var_size(u32 attributes, unsigned long size)
312 {
313 const struct efivar_operations *fops = __efivars->ops;
314
315 if (!fops->query_variable_store)
316 return EFI_UNSUPPORTED;
317
318 return fops->query_variable_store(attributes, size, false);
319 }
320
321 static efi_status_t
322 check_var_size_nonblocking(u32 attributes, unsigned long size)
323 {
324 const struct efivar_operations *fops = __efivars->ops;
325
326 if (!fops->query_variable_store)
327 return EFI_UNSUPPORTED;
328
329 return fops->query_variable_store(attributes, size, true);
330 }
331
332 static int efi_status_to_err(efi_status_t status)
333 {
334 int err;
335
336 switch (status) {
337 case EFI_SUCCESS:
338 err = 0;
339 break;
340 case EFI_INVALID_PARAMETER:
341 err = -EINVAL;
342 break;
343 case EFI_OUT_OF_RESOURCES:
344 err = -ENOSPC;
345 break;
346 case EFI_DEVICE_ERROR:
347 err = -EIO;
348 break;
349 case EFI_WRITE_PROTECTED:
350 err = -EROFS;
351 break;
352 case EFI_SECURITY_VIOLATION:
353 err = -EACCES;
354 break;
355 case EFI_NOT_FOUND:
356 err = -ENOENT;
357 break;
358 default:
359 err = -EINVAL;
360 }
361
362 return err;
363 }
364
365 static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor,
366 struct list_head *head)
367 {
368 struct efivar_entry *entry, *n;
369 unsigned long strsize1, strsize2;
370 bool found = false;
371
372 strsize1 = ucs2_strsize(variable_name, 1024);
373 list_for_each_entry_safe(entry, n, head, list) {
374 strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
375 if (strsize1 == strsize2 &&
376 !memcmp(variable_name, &(entry->var.VariableName),
377 strsize2) &&
378 !efi_guidcmp(entry->var.VendorGuid,
379 *vendor)) {
380 found = true;
381 break;
382 }
383 }
384 return found;
385 }
386
387 /*
388 * Returns the size of variable_name, in bytes, including the
389 * terminating NULL character, or variable_name_size if no NULL
390 * character is found among the first variable_name_size bytes.
391 */
392 static unsigned long var_name_strnsize(efi_char16_t *variable_name,
393 unsigned long variable_name_size)
394 {
395 unsigned long len;
396 efi_char16_t c;
397
398 /*
399 * The variable name is, by definition, a NULL-terminated
400 * string, so make absolutely sure that variable_name_size is
401 * the value we expect it to be. If not, return the real size.
402 */
403 for (len = 2; len <= variable_name_size; len += sizeof(c)) {
404 c = variable_name[(len / sizeof(c)) - 1];
405 if (!c)
406 break;
407 }
408
409 return min(len, variable_name_size);
410 }
411
412 /*
413 * Print a warning when duplicate EFI variables are encountered and
414 * disable the sysfs workqueue since the firmware is buggy.
415 */
416 static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid,
417 unsigned long len16)
418 {
419 size_t i, len8 = len16 / sizeof(efi_char16_t);
420 char *str8;
421
422 /*
423 * Disable the workqueue since the algorithm it uses for
424 * detecting new variables won't work with this buggy
425 * implementation of GetNextVariableName().
426 */
427 efivar_wq_enabled = false;
428
429 str8 = kzalloc(len8, GFP_KERNEL);
430 if (!str8)
431 return;
432
433 for (i = 0; i < len8; i++)
434 str8[i] = str16[i];
435
436 printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n",
437 str8, vendor_guid);
438 kfree(str8);
439 }
440
441 /**
442 * efivar_init - build the initial list of EFI variables
443 * @func: callback function to invoke for every variable
444 * @data: function-specific data to pass to @func
445 * @atomic: do we need to execute the @func-loop atomically?
446 * @duplicates: error if we encounter duplicates on @head?
447 * @head: initialised head of variable list
448 *
449 * Get every EFI variable from the firmware and invoke @func. @func
450 * should call efivar_entry_add() to build the list of variables.
451 *
452 * Returns 0 on success, or a kernel error code on failure.
453 */
454 int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
455 void *data, bool atomic, bool duplicates,
456 struct list_head *head)
457 {
458 const struct efivar_operations *ops = __efivars->ops;
459 unsigned long variable_name_size = 1024;
460 efi_char16_t *variable_name;
461 efi_status_t status;
462 efi_guid_t vendor_guid;
463 int err = 0;
464
465 variable_name = kzalloc(variable_name_size, GFP_KERNEL);
466 if (!variable_name) {
467 printk(KERN_ERR "efivars: Memory allocation failed.\n");
468 return -ENOMEM;
469 }
470
471 spin_lock_irq(&__efivars->lock);
472
473 /*
474 * Per EFI spec, the maximum storage allocated for both
475 * the variable name and variable data is 1024 bytes.
476 */
477
478 do {
479 variable_name_size = 1024;
480
481 status = ops->get_next_variable(&variable_name_size,
482 variable_name,
483 &vendor_guid);
484 switch (status) {
485 case EFI_SUCCESS:
486 if (!atomic)
487 spin_unlock_irq(&__efivars->lock);
488
489 variable_name_size = var_name_strnsize(variable_name,
490 variable_name_size);
491
492 /*
493 * Some firmware implementations return the
494 * same variable name on multiple calls to
495 * get_next_variable(). Terminate the loop
496 * immediately as there is no guarantee that
497 * we'll ever see a different variable name,
498 * and may end up looping here forever.
499 */
500 if (duplicates &&
501 variable_is_present(variable_name, &vendor_guid, head)) {
502 dup_variable_bug(variable_name, &vendor_guid,
503 variable_name_size);
504 if (!atomic)
505 spin_lock_irq(&__efivars->lock);
506
507 status = EFI_NOT_FOUND;
508 break;
509 }
510
511 err = func(variable_name, vendor_guid, variable_name_size, data);
512 if (err)
513 status = EFI_NOT_FOUND;
514
515 if (!atomic)
516 spin_lock_irq(&__efivars->lock);
517
518 break;
519 case EFI_NOT_FOUND:
520 break;
521 default:
522 printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
523 status);
524 status = EFI_NOT_FOUND;
525 break;
526 }
527
528 } while (status != EFI_NOT_FOUND);
529
530 spin_unlock_irq(&__efivars->lock);
531
532 kfree(variable_name);
533
534 return err;
535 }
536 EXPORT_SYMBOL_GPL(efivar_init);
537
538 /**
539 * efivar_entry_add - add entry to variable list
540 * @entry: entry to add to list
541 * @head: list head
542 */
543 void efivar_entry_add(struct efivar_entry *entry, struct list_head *head)
544 {
545 spin_lock_irq(&__efivars->lock);
546 list_add(&entry->list, head);
547 spin_unlock_irq(&__efivars->lock);
548 }
549 EXPORT_SYMBOL_GPL(efivar_entry_add);
550
551 /**
552 * efivar_entry_remove - remove entry from variable list
553 * @entry: entry to remove from list
554 */
555 void efivar_entry_remove(struct efivar_entry *entry)
556 {
557 spin_lock_irq(&__efivars->lock);
558 list_del(&entry->list);
559 spin_unlock_irq(&__efivars->lock);
560 }
561 EXPORT_SYMBOL_GPL(efivar_entry_remove);
562
563 /*
564 * efivar_entry_list_del_unlock - remove entry from variable list
565 * @entry: entry to remove
566 *
567 * Remove @entry from the variable list and release the list lock.
568 *
569 * NOTE: slightly weird locking semantics here - we expect to be
570 * called with the efivars lock already held, and we release it before
571 * returning. This is because this function is usually called after
572 * set_variable() while the lock is still held.
573 */
574 static void efivar_entry_list_del_unlock(struct efivar_entry *entry)
575 {
576 lockdep_assert_held(&__efivars->lock);
577
578 list_del(&entry->list);
579 spin_unlock_irq(&__efivars->lock);
580 }
581
582 /**
583 * __efivar_entry_delete - delete an EFI variable
584 * @entry: entry containing EFI variable to delete
585 *
586 * Delete the variable from the firmware but leave @entry on the
587 * variable list.
588 *
589 * This function differs from efivar_entry_delete() because it does
590 * not remove @entry from the variable list. Also, it is safe to be
591 * called from within a efivar_entry_iter_begin() and
592 * efivar_entry_iter_end() region, unlike efivar_entry_delete().
593 *
594 * Returns 0 on success, or a converted EFI status code if
595 * set_variable() fails.
596 */
597 int __efivar_entry_delete(struct efivar_entry *entry)
598 {
599 const struct efivar_operations *ops = __efivars->ops;
600 efi_status_t status;
601
602 lockdep_assert_held(&__efivars->lock);
603
604 status = ops->set_variable(entry->var.VariableName,
605 &entry->var.VendorGuid,
606 0, 0, NULL);
607
608 return efi_status_to_err(status);
609 }
610 EXPORT_SYMBOL_GPL(__efivar_entry_delete);
611
612 /**
613 * efivar_entry_delete - delete variable and remove entry from list
614 * @entry: entry containing variable to delete
615 *
616 * Delete the variable from the firmware and remove @entry from the
617 * variable list. It is the caller's responsibility to free @entry
618 * once we return.
619 *
620 * Returns 0 on success, or a converted EFI status code if
621 * set_variable() fails.
622 */
623 int efivar_entry_delete(struct efivar_entry *entry)
624 {
625 const struct efivar_operations *ops = __efivars->ops;
626 efi_status_t status;
627
628 spin_lock_irq(&__efivars->lock);
629 status = ops->set_variable(entry->var.VariableName,
630 &entry->var.VendorGuid,
631 0, 0, NULL);
632 if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND)) {
633 spin_unlock_irq(&__efivars->lock);
634 return efi_status_to_err(status);
635 }
636
637 efivar_entry_list_del_unlock(entry);
638 return 0;
639 }
640 EXPORT_SYMBOL_GPL(efivar_entry_delete);
641
642 /**
643 * efivar_entry_set - call set_variable()
644 * @entry: entry containing the EFI variable to write
645 * @attributes: variable attributes
646 * @size: size of @data buffer
647 * @data: buffer containing variable data
648 * @head: head of variable list
649 *
650 * Calls set_variable() for an EFI variable. If creating a new EFI
651 * variable, this function is usually followed by efivar_entry_add().
652 *
653 * Before writing the variable, the remaining EFI variable storage
654 * space is checked to ensure there is enough room available.
655 *
656 * If @head is not NULL a lookup is performed to determine whether
657 * the entry is already on the list.
658 *
659 * Returns 0 on success, -EEXIST if a lookup is performed and the entry
660 * already exists on the list, or a converted EFI status code if
661 * set_variable() fails.
662 */
663 int efivar_entry_set(struct efivar_entry *entry, u32 attributes,
664 unsigned long size, void *data, struct list_head *head)
665 {
666 const struct efivar_operations *ops = __efivars->ops;
667 efi_status_t status;
668 efi_char16_t *name = entry->var.VariableName;
669 efi_guid_t vendor = entry->var.VendorGuid;
670
671 spin_lock_irq(&__efivars->lock);
672
673 if (head && efivar_entry_find(name, vendor, head, false)) {
674 spin_unlock_irq(&__efivars->lock);
675 return -EEXIST;
676 }
677
678 status = check_var_size(attributes, size + ucs2_strsize(name, 1024));
679 if (status == EFI_SUCCESS || status == EFI_UNSUPPORTED)
680 status = ops->set_variable(name, &vendor,
681 attributes, size, data);
682
683 spin_unlock_irq(&__efivars->lock);
684
685 return efi_status_to_err(status);
686
687 }
688 EXPORT_SYMBOL_GPL(efivar_entry_set);
689
690 /*
691 * efivar_entry_set_nonblocking - call set_variable_nonblocking()
692 *
693 * This function is guaranteed to not block and is suitable for calling
694 * from crash/panic handlers.
695 *
696 * Crucially, this function will not block if it cannot acquire
697 * __efivars->lock. Instead, it returns -EBUSY.
698 */
699 static int
700 efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor,
701 u32 attributes, unsigned long size, void *data)
702 {
703 const struct efivar_operations *ops = __efivars->ops;
704 unsigned long flags;
705 efi_status_t status;
706
707 if (!spin_trylock_irqsave(&__efivars->lock, flags))
708 return -EBUSY;
709
710 status = check_var_size_nonblocking(attributes,
711 size + ucs2_strsize(name, 1024));
712 if (status != EFI_SUCCESS) {
713 spin_unlock_irqrestore(&__efivars->lock, flags);
714 return -ENOSPC;
715 }
716
717 status = ops->set_variable_nonblocking(name, &vendor, attributes,
718 size, data);
719
720 spin_unlock_irqrestore(&__efivars->lock, flags);
721 return efi_status_to_err(status);
722 }
723
724 /**
725 * efivar_entry_set_safe - call set_variable() if enough space in firmware
726 * @name: buffer containing the variable name
727 * @vendor: variable vendor guid
728 * @attributes: variable attributes
729 * @block: can we block in this context?
730 * @size: size of @data buffer
731 * @data: buffer containing variable data
732 *
733 * Ensures there is enough free storage in the firmware for this variable, and
734 * if so, calls set_variable(). If creating a new EFI variable, this function
735 * is usually followed by efivar_entry_add().
736 *
737 * Returns 0 on success, -ENOSPC if the firmware does not have enough
738 * space for set_variable() to succeed, or a converted EFI status code
739 * if set_variable() fails.
740 */
741 int efivar_entry_set_safe(efi_char16_t *name, efi_guid_t vendor, u32 attributes,
742 bool block, unsigned long size, void *data)
743 {
744 const struct efivar_operations *ops = __efivars->ops;
745 unsigned long flags;
746 efi_status_t status;
747
748 if (!ops->query_variable_store)
749 return -ENOSYS;
750
751 /*
752 * If the EFI variable backend provides a non-blocking
753 * ->set_variable() operation and we're in a context where we
754 * cannot block, then we need to use it to avoid live-locks,
755 * since the implication is that the regular ->set_variable()
756 * will block.
757 *
758 * If no ->set_variable_nonblocking() is provided then
759 * ->set_variable() is assumed to be non-blocking.
760 */
761 if (!block && ops->set_variable_nonblocking)
762 return efivar_entry_set_nonblocking(name, vendor, attributes,
763 size, data);
764
765 if (!block) {
766 if (!spin_trylock_irqsave(&__efivars->lock, flags))
767 return -EBUSY;
768 } else {
769 spin_lock_irqsave(&__efivars->lock, flags);
770 }
771
772 status = check_var_size(attributes, size + ucs2_strsize(name, 1024));
773 if (status != EFI_SUCCESS) {
774 spin_unlock_irqrestore(&__efivars->lock, flags);
775 return -ENOSPC;
776 }
777
778 status = ops->set_variable(name, &vendor, attributes, size, data);
779
780 spin_unlock_irqrestore(&__efivars->lock, flags);
781
782 return efi_status_to_err(status);
783 }
784 EXPORT_SYMBOL_GPL(efivar_entry_set_safe);
785
786 /**
787 * efivar_entry_find - search for an entry
788 * @name: the EFI variable name
789 * @guid: the EFI variable vendor's guid
790 * @head: head of the variable list
791 * @remove: should we remove the entry from the list?
792 *
793 * Search for an entry on the variable list that has the EFI variable
794 * name @name and vendor guid @guid. If an entry is found on the list
795 * and @remove is true, the entry is removed from the list.
796 *
797 * The caller MUST call efivar_entry_iter_begin() and
798 * efivar_entry_iter_end() before and after the invocation of this
799 * function, respectively.
800 *
801 * Returns the entry if found on the list, %NULL otherwise.
802 */
803 struct efivar_entry *efivar_entry_find(efi_char16_t *name, efi_guid_t guid,
804 struct list_head *head, bool remove)
805 {
806 struct efivar_entry *entry, *n;
807 int strsize1, strsize2;
808 bool found = false;
809
810 lockdep_assert_held(&__efivars->lock);
811
812 list_for_each_entry_safe(entry, n, head, list) {
813 strsize1 = ucs2_strsize(name, 1024);
814 strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
815 if (strsize1 == strsize2 &&
816 !memcmp(name, &(entry->var.VariableName), strsize1) &&
817 !efi_guidcmp(guid, entry->var.VendorGuid)) {
818 found = true;
819 break;
820 }
821 }
822
823 if (!found)
824 return NULL;
825
826 if (remove) {
827 if (entry->scanning) {
828 /*
829 * The entry will be deleted
830 * after scanning is completed.
831 */
832 entry->deleting = true;
833 } else
834 list_del(&entry->list);
835 }
836
837 return entry;
838 }
839 EXPORT_SYMBOL_GPL(efivar_entry_find);
840
841 /**
842 * efivar_entry_size - obtain the size of a variable
843 * @entry: entry for this variable
844 * @size: location to store the variable's size
845 */
846 int efivar_entry_size(struct efivar_entry *entry, unsigned long *size)
847 {
848 const struct efivar_operations *ops = __efivars->ops;
849 efi_status_t status;
850
851 *size = 0;
852
853 spin_lock_irq(&__efivars->lock);
854 status = ops->get_variable(entry->var.VariableName,
855 &entry->var.VendorGuid, NULL, size, NULL);
856 spin_unlock_irq(&__efivars->lock);
857
858 if (status != EFI_BUFFER_TOO_SMALL)
859 return efi_status_to_err(status);
860
861 return 0;
862 }
863 EXPORT_SYMBOL_GPL(efivar_entry_size);
864
865 /**
866 * __efivar_entry_get - call get_variable()
867 * @entry: read data for this variable
868 * @attributes: variable attributes
869 * @size: size of @data buffer
870 * @data: buffer to store variable data
871 *
872 * The caller MUST call efivar_entry_iter_begin() and
873 * efivar_entry_iter_end() before and after the invocation of this
874 * function, respectively.
875 */
876 int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
877 unsigned long *size, void *data)
878 {
879 const struct efivar_operations *ops = __efivars->ops;
880 efi_status_t status;
881
882 lockdep_assert_held(&__efivars->lock);
883
884 status = ops->get_variable(entry->var.VariableName,
885 &entry->var.VendorGuid,
886 attributes, size, data);
887
888 return efi_status_to_err(status);
889 }
890 EXPORT_SYMBOL_GPL(__efivar_entry_get);
891
892 /**
893 * efivar_entry_get - call get_variable()
894 * @entry: read data for this variable
895 * @attributes: variable attributes
896 * @size: size of @data buffer
897 * @data: buffer to store variable data
898 */
899 int efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
900 unsigned long *size, void *data)
901 {
902 const struct efivar_operations *ops = __efivars->ops;
903 efi_status_t status;
904
905 spin_lock_irq(&__efivars->lock);
906 status = ops->get_variable(entry->var.VariableName,
907 &entry->var.VendorGuid,
908 attributes, size, data);
909 spin_unlock_irq(&__efivars->lock);
910
911 return efi_status_to_err(status);
912 }
913 EXPORT_SYMBOL_GPL(efivar_entry_get);
914
915 /**
916 * efivar_entry_set_get_size - call set_variable() and get new size (atomic)
917 * @entry: entry containing variable to set and get
918 * @attributes: attributes of variable to be written
919 * @size: size of data buffer
920 * @data: buffer containing data to write
921 * @set: did the set_variable() call succeed?
922 *
923 * This is a pretty special (complex) function. See efivarfs_file_write().
924 *
925 * Atomically call set_variable() for @entry and if the call is
926 * successful, return the new size of the variable from get_variable()
927 * in @size. The success of set_variable() is indicated by @set.
928 *
929 * Returns 0 on success, -EINVAL if the variable data is invalid,
930 * -ENOSPC if the firmware does not have enough available space, or a
931 * converted EFI status code if either of set_variable() or
932 * get_variable() fail.
933 *
934 * If the EFI variable does not exist when calling set_variable()
935 * (EFI_NOT_FOUND), @entry is removed from the variable list.
936 */
937 int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
938 unsigned long *size, void *data, bool *set)
939 {
940 const struct efivar_operations *ops = __efivars->ops;
941 efi_char16_t *name = entry->var.VariableName;
942 efi_guid_t *vendor = &entry->var.VendorGuid;
943 efi_status_t status;
944 int err;
945
946 *set = false;
947
948 if (efivar_validate(*vendor, name, data, *size) == false)
949 return -EINVAL;
950
951 /*
952 * The lock here protects the get_variable call, the conditional
953 * set_variable call, and removal of the variable from the efivars
954 * list (in the case of an authenticated delete).
955 */
956 spin_lock_irq(&__efivars->lock);
957
958 /*
959 * Ensure that the available space hasn't shrunk below the safe level
960 */
961 status = check_var_size(attributes, *size + ucs2_strsize(name, 1024));
962 if (status != EFI_SUCCESS) {
963 if (status != EFI_UNSUPPORTED) {
964 err = efi_status_to_err(status);
965 goto out;
966 }
967
968 if (*size > 65536) {
969 err = -ENOSPC;
970 goto out;
971 }
972 }
973
974 status = ops->set_variable(name, vendor, attributes, *size, data);
975 if (status != EFI_SUCCESS) {
976 err = efi_status_to_err(status);
977 goto out;
978 }
979
980 *set = true;
981
982 /*
983 * Writing to the variable may have caused a change in size (which
984 * could either be an append or an overwrite), or the variable to be
985 * deleted. Perform a GetVariable() so we can tell what actually
986 * happened.
987 */
988 *size = 0;
989 status = ops->get_variable(entry->var.VariableName,
990 &entry->var.VendorGuid,
991 NULL, size, NULL);
992
993 if (status == EFI_NOT_FOUND)
994 efivar_entry_list_del_unlock(entry);
995 else
996 spin_unlock_irq(&__efivars->lock);
997
998 if (status && status != EFI_BUFFER_TOO_SMALL)
999 return efi_status_to_err(status);
1000
1001 return 0;
1002
1003 out:
1004 spin_unlock_irq(&__efivars->lock);
1005 return err;
1006
1007 }
1008 EXPORT_SYMBOL_GPL(efivar_entry_set_get_size);
1009
1010 /**
1011 * efivar_entry_iter_begin - begin iterating the variable list
1012 *
1013 * Lock the variable list to prevent entry insertion and removal until
1014 * efivar_entry_iter_end() is called. This function is usually used in
1015 * conjunction with __efivar_entry_iter() or efivar_entry_iter().
1016 */
1017 void efivar_entry_iter_begin(void)
1018 {
1019 spin_lock_irq(&__efivars->lock);
1020 }
1021 EXPORT_SYMBOL_GPL(efivar_entry_iter_begin);
1022
1023 /**
1024 * efivar_entry_iter_end - finish iterating the variable list
1025 *
1026 * Unlock the variable list and allow modifications to the list again.
1027 */
1028 void efivar_entry_iter_end(void)
1029 {
1030 spin_unlock_irq(&__efivars->lock);
1031 }
1032 EXPORT_SYMBOL_GPL(efivar_entry_iter_end);
1033
1034 /**
1035 * __efivar_entry_iter - iterate over variable list
1036 * @func: callback function
1037 * @head: head of the variable list
1038 * @data: function-specific data to pass to callback
1039 * @prev: entry to begin iterating from
1040 *
1041 * Iterate over the list of EFI variables and call @func with every
1042 * entry on the list. It is safe for @func to remove entries in the
1043 * list via efivar_entry_delete().
1044 *
1045 * You MUST call efivar_enter_iter_begin() before this function, and
1046 * efivar_entry_iter_end() afterwards.
1047 *
1048 * It is possible to begin iteration from an arbitrary entry within
1049 * the list by passing @prev. @prev is updated on return to point to
1050 * the last entry passed to @func. To begin iterating from the
1051 * beginning of the list @prev must be %NULL.
1052 *
1053 * The restrictions for @func are the same as documented for
1054 * efivar_entry_iter().
1055 */
1056 int __efivar_entry_iter(int (*func)(struct efivar_entry *, void *),
1057 struct list_head *head, void *data,
1058 struct efivar_entry **prev)
1059 {
1060 struct efivar_entry *entry, *n;
1061 int err = 0;
1062
1063 if (!prev || !*prev) {
1064 list_for_each_entry_safe(entry, n, head, list) {
1065 err = func(entry, data);
1066 if (err)
1067 break;
1068 }
1069
1070 if (prev)
1071 *prev = entry;
1072
1073 return err;
1074 }
1075
1076
1077 list_for_each_entry_safe_continue((*prev), n, head, list) {
1078 err = func(*prev, data);
1079 if (err)
1080 break;
1081 }
1082
1083 return err;
1084 }
1085 EXPORT_SYMBOL_GPL(__efivar_entry_iter);
1086
1087 /**
1088 * efivar_entry_iter - iterate over variable list
1089 * @func: callback function
1090 * @head: head of variable list
1091 * @data: function-specific data to pass to callback
1092 *
1093 * Iterate over the list of EFI variables and call @func with every
1094 * entry on the list. It is safe for @func to remove entries in the
1095 * list via efivar_entry_delete() while iterating.
1096 *
1097 * Some notes for the callback function:
1098 * - a non-zero return value indicates an error and terminates the loop
1099 * - @func is called from atomic context
1100 */
1101 int efivar_entry_iter(int (*func)(struct efivar_entry *, void *),
1102 struct list_head *head, void *data)
1103 {
1104 int err = 0;
1105
1106 efivar_entry_iter_begin();
1107 err = __efivar_entry_iter(func, head, data, NULL);
1108 efivar_entry_iter_end();
1109
1110 return err;
1111 }
1112 EXPORT_SYMBOL_GPL(efivar_entry_iter);
1113
1114 /**
1115 * efivars_kobject - get the kobject for the registered efivars
1116 *
1117 * If efivars_register() has not been called we return NULL,
1118 * otherwise return the kobject used at registration time.
1119 */
1120 struct kobject *efivars_kobject(void)
1121 {
1122 if (!__efivars)
1123 return NULL;
1124
1125 return __efivars->kobject;
1126 }
1127 EXPORT_SYMBOL_GPL(efivars_kobject);
1128
1129 /**
1130 * efivar_run_worker - schedule the efivar worker thread
1131 */
1132 void efivar_run_worker(void)
1133 {
1134 if (efivar_wq_enabled)
1135 schedule_work(&efivar_work);
1136 }
1137 EXPORT_SYMBOL_GPL(efivar_run_worker);
1138
1139 /**
1140 * efivars_register - register an efivars
1141 * @efivars: efivars to register
1142 * @ops: efivars operations
1143 * @kobject: @efivars-specific kobject
1144 *
1145 * Only a single efivars can be registered at any time.
1146 */
1147 int efivars_register(struct efivars *efivars,
1148 const struct efivar_operations *ops,
1149 struct kobject *kobject)
1150 {
1151 spin_lock_init(&efivars->lock);
1152 efivars->ops = ops;
1153 efivars->kobject = kobject;
1154
1155 __efivars = efivars;
1156
1157 return 0;
1158 }
1159 EXPORT_SYMBOL_GPL(efivars_register);
1160
1161 /**
1162 * efivars_unregister - unregister an efivars
1163 * @efivars: efivars to unregister
1164 *
1165 * The caller must have already removed every entry from the list,
1166 * failure to do so is an error.
1167 */
1168 int efivars_unregister(struct efivars *efivars)
1169 {
1170 int rv;
1171
1172 if (!__efivars) {
1173 printk(KERN_ERR "efivars not registered\n");
1174 rv = -EINVAL;
1175 goto out;
1176 }
1177
1178 if (__efivars != efivars) {
1179 rv = -EINVAL;
1180 goto out;
1181 }
1182
1183 __efivars = NULL;
1184
1185 rv = 0;
1186 out:
1187 return rv;
1188 }
1189 EXPORT_SYMBOL_GPL(efivars_unregister);
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