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
validate_device_path(efi_char16_t * var_name,int match,u8 * buffer,unsigned long len)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
validate_boot_order(efi_char16_t * var_name,int match,u8 * buffer,unsigned long len)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
validate_load_option(efi_char16_t * var_name,int match,u8 * buffer,unsigned long len)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(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(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((efi_char16_t *)(buffer + 6), 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 + desclength + 6,
119 				    filepathlength);
120 }
121 
122 static bool
validate_uint16(efi_char16_t * var_name,int match,u8 * buffer,unsigned long len)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
validate_ascii_string(efi_char16_t * var_name,int match,u8 * buffer,unsigned long len)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
variable_matches(const char * var_name,size_t len,const char * match_name,int * match)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
efivar_validate(efi_guid_t vendor,efi_char16_t * var_name,u8 * data,unsigned long data_size)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(var_name);
237 	utf8_name = kmalloc(utf8_size + 1, GFP_KERNEL);
238 	if (!utf8_name)
239 		return false;
240 
241 	ucs2_as_utf8(utf8_name, var_name, 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(vendor, variable_validate[i].vendor))
249 			continue;
250 
251 		if (variable_matches(utf8_name, utf8_size+1, name, &match)) {
252 			if (variable_validate[i].validate == NULL)
253 				break;
254 			kfree(utf8_name);
255 			return variable_validate[i].validate(var_name, match,
256 							     data, data_size);
257 		}
258 	}
259 	kfree(utf8_name);
260 	return true;
261 }
262 
263 bool
efivar_variable_is_removable(efi_guid_t vendor,const char * var_name,size_t len)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(variable_validate[i].vendor, vendor))
276 			continue;
277 
278 		if (variable_matches(var_name, len,
279 				     variable_validate[i].name, &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 
variable_is_present(efi_char16_t * variable_name,efi_guid_t * vendor,struct list_head * head)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(variable_name, 1024);
299 	list_for_each_entry_safe(entry, n, head, list) {
300 		strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
301 		if (strsize1 == strsize2 &&
302 			!memcmp(variable_name, &(entry->var.VariableName),
303 				strsize2) &&
304 			!efi_guidcmp(entry->var.VendorGuid,
305 				*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  */
var_name_strnsize(efi_char16_t * variable_name,unsigned long variable_name_size)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  */
dup_variable_bug(efi_char16_t * str16,efi_guid_t * vendor_guid,unsigned long len16)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(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(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  * @duplicates: error if we encounter duplicates on @head?
365  * @head: initialised head of variable list
366  *
367  * Get every EFI variable from the firmware and invoke @func. @func
368  * should call efivar_entry_add() to build the list of variables.
369  *
370  * Returns 0 on success, or a kernel error code on failure.
371  */
efivar_init(int (* func)(efi_char16_t *,efi_guid_t,unsigned long,void *),void * data,bool duplicates,struct list_head * head)372 int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
373 		void *data, bool duplicates, struct list_head *head)
374 {
375 	unsigned long variable_name_size = 1024;
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(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 	 * Per EFI spec, the maximum storage allocated for both
393 	 * the variable name and variable data is 1024 bytes.
394 	 */
395 
396 	do {
397 		variable_name_size = 1024;
398 
399 		status = efivar_get_next_variable(&variable_name_size,
400 						  variable_name,
401 						  &vendor_guid);
402 		switch (status) {
403 		case EFI_SUCCESS:
404 			variable_name_size = var_name_strnsize(variable_name,
405 							       variable_name_size);
406 
407 			/*
408 			 * Some firmware implementations return the
409 			 * same variable name on multiple calls to
410 			 * get_next_variable(). Terminate the loop
411 			 * immediately as there is no guarantee that
412 			 * we'll ever see a different variable name,
413 			 * and may end up looping here forever.
414 			 */
415 			if (duplicates &&
416 			    variable_is_present(variable_name, &vendor_guid,
417 						head)) {
418 				dup_variable_bug(variable_name, &vendor_guid,
419 						 variable_name_size);
420 				status = EFI_NOT_FOUND;
421 			} else {
422 				err = func(variable_name, vendor_guid,
423 					   variable_name_size, data);
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 		default:
435 			printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
436 				status);
437 			status = EFI_NOT_FOUND;
438 			break;
439 		}
440 
441 	} while (status != EFI_NOT_FOUND);
442 
443 	efivar_unlock();
444 free:
445 	kfree(variable_name);
446 
447 	return err;
448 }
449 
450 /**
451  * efivar_entry_add - add entry to variable list
452  * @entry: entry to add to list
453  * @head: list head
454  *
455  * Returns 0 on success, or a kernel error code on failure.
456  */
efivar_entry_add(struct efivar_entry * entry,struct list_head * head)457 int efivar_entry_add(struct efivar_entry *entry, struct list_head *head)
458 {
459 	int err;
460 
461 	err = efivar_lock();
462 	if (err)
463 		return err;
464 	list_add(&entry->list, head);
465 	efivar_unlock();
466 
467 	return 0;
468 }
469 
470 /**
471  * __efivar_entry_add - add entry to variable list
472  * @entry: entry to add to list
473  * @head: list head
474  */
__efivar_entry_add(struct efivar_entry * entry,struct list_head * head)475 void __efivar_entry_add(struct efivar_entry *entry, struct list_head *head)
476 {
477 	list_add(&entry->list, head);
478 }
479 
480 /**
481  * efivar_entry_remove - remove entry from variable list
482  * @entry: entry to remove from list
483  *
484  * Returns 0 on success, or a kernel error code on failure.
485  */
efivar_entry_remove(struct efivar_entry * entry)486 void efivar_entry_remove(struct efivar_entry *entry)
487 {
488 	list_del(&entry->list);
489 }
490 
491 /*
492  * efivar_entry_list_del_unlock - remove entry from variable list
493  * @entry: entry to remove
494  *
495  * Remove @entry from the variable list and release the list lock.
496  *
497  * NOTE: slightly weird locking semantics here - we expect to be
498  * called with the efivars lock already held, and we release it before
499  * returning. This is because this function is usually called after
500  * set_variable() while the lock is still held.
501  */
efivar_entry_list_del_unlock(struct efivar_entry * entry)502 static void efivar_entry_list_del_unlock(struct efivar_entry *entry)
503 {
504 	list_del(&entry->list);
505 	efivar_unlock();
506 }
507 
508 /**
509  * efivar_entry_delete - delete variable and remove entry from list
510  * @entry: entry containing variable to delete
511  *
512  * Delete the variable from the firmware and remove @entry from the
513  * variable list. It is the caller's responsibility to free @entry
514  * once we return.
515  *
516  * Returns 0 on success, -EINTR if we can't grab the semaphore,
517  * converted EFI status code if set_variable() fails.
518  */
efivar_entry_delete(struct efivar_entry * entry)519 int efivar_entry_delete(struct efivar_entry *entry)
520 {
521 	efi_status_t status;
522 	int err;
523 
524 	err = efivar_lock();
525 	if (err)
526 		return err;
527 
528 	status = efivar_set_variable_locked(entry->var.VariableName,
529 					    &entry->var.VendorGuid,
530 					    0, 0, NULL, false);
531 	if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND)) {
532 		efivar_unlock();
533 		return efi_status_to_err(status);
534 	}
535 
536 	efivar_entry_list_del_unlock(entry);
537 	return 0;
538 }
539 
540 /**
541  * efivar_entry_size - obtain the size of a variable
542  * @entry: entry for this variable
543  * @size: location to store the variable's size
544  */
efivar_entry_size(struct efivar_entry * entry,unsigned long * size)545 int efivar_entry_size(struct efivar_entry *entry, unsigned long *size)
546 {
547 	efi_status_t status;
548 	int err;
549 
550 	*size = 0;
551 
552 	err = efivar_lock();
553 	if (err)
554 		return err;
555 
556 	status = efivar_get_variable(entry->var.VariableName,
557 				     &entry->var.VendorGuid, NULL, size, NULL);
558 	efivar_unlock();
559 
560 	if (status != EFI_BUFFER_TOO_SMALL)
561 		return efi_status_to_err(status);
562 
563 	return 0;
564 }
565 
566 /**
567  * __efivar_entry_get - call get_variable()
568  * @entry: read data for this variable
569  * @attributes: variable attributes
570  * @size: size of @data buffer
571  * @data: buffer to store variable data
572  *
573  * The caller MUST call efivar_entry_iter_begin() and
574  * efivar_entry_iter_end() before and after the invocation of this
575  * function, respectively.
576  */
__efivar_entry_get(struct efivar_entry * entry,u32 * attributes,unsigned long * size,void * data)577 int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
578 		       unsigned long *size, void *data)
579 {
580 	efi_status_t status;
581 
582 	status = efivar_get_variable(entry->var.VariableName,
583 				     &entry->var.VendorGuid,
584 				     attributes, size, data);
585 
586 	return efi_status_to_err(status);
587 }
588 
589 /**
590  * efivar_entry_get - call get_variable()
591  * @entry: read data for this variable
592  * @attributes: variable attributes
593  * @size: size of @data buffer
594  * @data: buffer to store variable data
595  */
efivar_entry_get(struct efivar_entry * entry,u32 * attributes,unsigned long * size,void * data)596 int efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
597 		     unsigned long *size, void *data)
598 {
599 	int err;
600 
601 	err = efivar_lock();
602 	if (err)
603 		return err;
604 	err = __efivar_entry_get(entry, attributes, size, data);
605 	efivar_unlock();
606 
607 	return 0;
608 }
609 
610 /**
611  * efivar_entry_set_get_size - call set_variable() and get new size (atomic)
612  * @entry: entry containing variable to set and get
613  * @attributes: attributes of variable to be written
614  * @size: size of data buffer
615  * @data: buffer containing data to write
616  * @set: did the set_variable() call succeed?
617  *
618  * This is a pretty special (complex) function. See efivarfs_file_write().
619  *
620  * Atomically call set_variable() for @entry and if the call is
621  * successful, return the new size of the variable from get_variable()
622  * in @size. The success of set_variable() is indicated by @set.
623  *
624  * Returns 0 on success, -EINVAL if the variable data is invalid,
625  * -ENOSPC if the firmware does not have enough available space, or a
626  * converted EFI status code if either of set_variable() or
627  * get_variable() fail.
628  *
629  * If the EFI variable does not exist when calling set_variable()
630  * (EFI_NOT_FOUND), @entry is removed from the variable list.
631  */
efivar_entry_set_get_size(struct efivar_entry * entry,u32 attributes,unsigned long * size,void * data,bool * set)632 int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
633 			      unsigned long *size, void *data, bool *set)
634 {
635 	efi_char16_t *name = entry->var.VariableName;
636 	efi_guid_t *vendor = &entry->var.VendorGuid;
637 	efi_status_t status;
638 	int err;
639 
640 	*set = false;
641 
642 	if (efivar_validate(*vendor, name, data, *size) == false)
643 		return -EINVAL;
644 
645 	/*
646 	 * The lock here protects the get_variable call, the conditional
647 	 * set_variable call, and removal of the variable from the efivars
648 	 * list (in the case of an authenticated delete).
649 	 */
650 	err = efivar_lock();
651 	if (err)
652 		return err;
653 
654 	status = efivar_set_variable_locked(name, vendor, attributes, *size,
655 					    data, false);
656 	if (status != EFI_SUCCESS) {
657 		err = efi_status_to_err(status);
658 		goto out;
659 	}
660 
661 	*set = true;
662 
663 	/*
664 	 * Writing to the variable may have caused a change in size (which
665 	 * could either be an append or an overwrite), or the variable to be
666 	 * deleted. Perform a GetVariable() so we can tell what actually
667 	 * happened.
668 	 */
669 	*size = 0;
670 	status = efivar_get_variable(entry->var.VariableName,
671 				    &entry->var.VendorGuid,
672 				    NULL, size, NULL);
673 
674 	if (status == EFI_NOT_FOUND)
675 		efivar_entry_list_del_unlock(entry);
676 	else
677 		efivar_unlock();
678 
679 	if (status && status != EFI_BUFFER_TOO_SMALL)
680 		return efi_status_to_err(status);
681 
682 	return 0;
683 
684 out:
685 	efivar_unlock();
686 	return err;
687 
688 }
689 
690 /**
691  * efivar_entry_iter - iterate over variable list
692  * @func: callback function
693  * @head: head of variable list
694  * @data: function-specific data to pass to callback
695  *
696  * Iterate over the list of EFI variables and call @func with every
697  * entry on the list. It is safe for @func to remove entries in the
698  * list via efivar_entry_delete() while iterating.
699  *
700  * Some notes for the callback function:
701  *  - a non-zero return value indicates an error and terminates the loop
702  *  - @func is called from atomic context
703  */
efivar_entry_iter(int (* func)(struct efivar_entry *,void *),struct list_head * head,void * data)704 int efivar_entry_iter(int (*func)(struct efivar_entry *, void *),
705 		      struct list_head *head, void *data)
706 {
707 	struct efivar_entry *entry, *n;
708 	int err = 0;
709 
710 	err = efivar_lock();
711 	if (err)
712 		return err;
713 
714 	list_for_each_entry_safe(entry, n, head, list) {
715 		err = func(entry, data);
716 		if (err)
717 			break;
718 	}
719 	efivar_unlock();
720 
721 	return err;
722 }
723