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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#define pr_fmt(fmt) "efivars: " fmt
10
11#include <linux/types.h>
12#include <linux/sizes.h>
13#include <linux/errno.h>
14#include <linux/init.h>
15#include <linux/module.h>
16#include <linux/string.h>
17#include <linux/smp.h>
18#include <linux/efi.h>
19#include <linux/ucs2_string.h>
20
21/* Private pointer to registered efivars */
22static struct efivars *__efivars;
23
24static DEFINE_SEMAPHORE(efivars_lock, 1);
25
26static efi_status_t check_var_size(bool nonblocking, u32 attributes,
27 unsigned long size)
28{
29 const struct efivar_operations *fops;
30 efi_status_t status;
31
32 fops = __efivars->ops;
33
34 if (!fops->query_variable_store)
35 status = EFI_UNSUPPORTED;
36 else
37 status = fops->query_variable_store(attributes, size,
38 nonblocking);
39 if (status == EFI_UNSUPPORTED)
40 return (size <= SZ_64K) ? EFI_SUCCESS : EFI_OUT_OF_RESOURCES;
41 return status;
42}
43
44/**
45 * efivar_is_available - check if efivars is available
46 *
47 * @return true iff evivars is currently registered
48 */
49bool efivar_is_available(void)
50{
51 return __efivars != NULL;
52}
53EXPORT_SYMBOL_GPL(efivar_is_available);
54
55/**
56 * efivars_register - register an efivars
57 * @efivars: efivars to register
58 * @ops: efivars operations
59 *
60 * Only a single efivars can be registered at any time.
61 */
62int efivars_register(struct efivars *efivars,
63 const struct efivar_operations *ops)
64{
65 int rv;
66 int event;
67
68 if (down_interruptible(&efivars_lock))
69 return -EINTR;
70
71 if (__efivars) {
72 pr_warn("efivars already registered\n");
73 rv = -EBUSY;
74 goto out;
75 }
76
77 efivars->ops = ops;
78
79 __efivars = efivars;
80
81 if (efivar_supports_writes())
82 event = EFIVAR_OPS_RDWR;
83 else
84 event = EFIVAR_OPS_RDONLY;
85
86 blocking_notifier_call_chain(&efivar_ops_nh, event, NULL);
87
88 pr_info("Registered efivars operations\n");
89 rv = 0;
90out:
91 up(&efivars_lock);
92
93 return rv;
94}
95EXPORT_SYMBOL_GPL(efivars_register);
96
97/**
98 * efivars_unregister - unregister an efivars
99 * @efivars: efivars to unregister
100 *
101 * The caller must have already removed every entry from the list,
102 * failure to do so is an error.
103 */
104int efivars_unregister(struct efivars *efivars)
105{
106 int rv;
107
108 if (down_interruptible(&efivars_lock))
109 return -EINTR;
110
111 if (!__efivars) {
112 pr_err("efivars not registered\n");
113 rv = -EINVAL;
114 goto out;
115 }
116
117 if (__efivars != efivars) {
118 rv = -EINVAL;
119 goto out;
120 }
121
122 pr_info("Unregistered efivars operations\n");
123 __efivars = NULL;
124
125 rv = 0;
126out:
127 up(&efivars_lock);
128 return rv;
129}
130EXPORT_SYMBOL_GPL(efivars_unregister);
131
132bool efivar_supports_writes(void)
133{
134 return __efivars && __efivars->ops->set_variable;
135}
136EXPORT_SYMBOL_GPL(efivar_supports_writes);
137
138/*
139 * efivar_lock() - obtain the efivar lock, wait for it if needed
140 * @return 0 on success, error code on failure
141 */
142int efivar_lock(void)
143{
144 if (down_interruptible(&efivars_lock))
145 return -EINTR;
146 if (!__efivars->ops) {
147 up(&efivars_lock);
148 return -ENODEV;
149 }
150 return 0;
151}
152EXPORT_SYMBOL_NS_GPL(efivar_lock, "EFIVAR");
153
154/*
155 * efivar_lock() - obtain the efivar lock if it is free
156 * @return 0 on success, error code on failure
157 */
158int efivar_trylock(void)
159{
160 if (down_trylock(&efivars_lock))
161 return -EBUSY;
162 if (!__efivars->ops) {
163 up(&efivars_lock);
164 return -ENODEV;
165 }
166 return 0;
167}
168EXPORT_SYMBOL_NS_GPL(efivar_trylock, "EFIVAR");
169
170/*
171 * efivar_unlock() - release the efivar lock
172 */
173void efivar_unlock(void)
174{
175 up(&efivars_lock);
176}
177EXPORT_SYMBOL_NS_GPL(efivar_unlock, "EFIVAR");
178
179/*
180 * efivar_get_variable() - retrieve a variable identified by name/vendor
181 *
182 * Must be called with efivars_lock held.
183 */
184efi_status_t efivar_get_variable(efi_char16_t *name, efi_guid_t *vendor,
185 u32 *attr, unsigned long *size, void *data)
186{
187 return __efivars->ops->get_variable(name, vendor, attr, size, data);
188}
189EXPORT_SYMBOL_NS_GPL(efivar_get_variable, "EFIVAR");
190
191/*
192 * efivar_get_next_variable() - enumerate the next name/vendor pair
193 *
194 * Must be called with efivars_lock held.
195 */
196efi_status_t efivar_get_next_variable(unsigned long *name_size,
197 efi_char16_t *name, efi_guid_t *vendor)
198{
199 return __efivars->ops->get_next_variable(name_size, name, vendor);
200}
201EXPORT_SYMBOL_NS_GPL(efivar_get_next_variable, "EFIVAR");
202
203/*
204 * efivar_set_variable_locked() - set a variable identified by name/vendor
205 *
206 * Must be called with efivars_lock held. If @nonblocking is set, it will use
207 * non-blocking primitives so it is guaranteed not to sleep.
208 */
209efi_status_t efivar_set_variable_locked(efi_char16_t *name, efi_guid_t *vendor,
210 u32 attr, unsigned long data_size,
211 void *data, bool nonblocking)
212{
213 efi_set_variable_t *setvar;
214 efi_status_t status;
215
216 if (data_size > 0) {
217 status = check_var_size(nonblocking, attr,
218 data_size + ucs2_strsize(name, EFI_VAR_NAME_LEN));
219 if (status != EFI_SUCCESS)
220 return status;
221 }
222
223 /*
224 * If no _nonblocking variant exists, the ordinary one
225 * is assumed to be non-blocking.
226 */
227 setvar = __efivars->ops->set_variable_nonblocking;
228 if (!setvar || !nonblocking)
229 setvar = __efivars->ops->set_variable;
230
231 return setvar(name, vendor, attr, data_size, data);
232}
233EXPORT_SYMBOL_NS_GPL(efivar_set_variable_locked, "EFIVAR");
234
235/*
236 * efivar_set_variable() - set a variable identified by name/vendor
237 *
238 * Can be called without holding the efivars_lock. Will sleep on obtaining the
239 * lock, or on obtaining other locks that are needed in order to complete the
240 * call.
241 */
242efi_status_t efivar_set_variable(efi_char16_t *name, efi_guid_t *vendor,
243 u32 attr, unsigned long data_size, void *data)
244{
245 efi_status_t status;
246
247 if (efivar_lock())
248 return EFI_ABORTED;
249
250 status = efivar_set_variable_locked(name, vendor, attr, data_size,
251 data, false);
252 efivar_unlock();
253 return status;
254}
255EXPORT_SYMBOL_NS_GPL(efivar_set_variable, "EFIVAR");
256
257efi_status_t efivar_query_variable_info(u32 attr,
258 u64 *storage_space,
259 u64 *remaining_space,
260 u64 *max_variable_size)
261{
262 if (!__efivars->ops->query_variable_info)
263 return EFI_UNSUPPORTED;
264 return __efivars->ops->query_variable_info(attr, storage_space,
265 remaining_space, max_variable_size);
266}
267EXPORT_SYMBOL_NS_GPL(efivar_query_variable_info, "EFIVAR");
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/sysfs.h>
19#include <linux/device.h>
20#include <linux/slab.h>
21#include <linux/ctype.h>
22#include <linux/ucs2_string.h>
23
24/* Private pointer to registered efivars */
25static struct efivars *__efivars;
26
27/*
28 * efivars_lock protects three things:
29 * 1) efivarfs_list and efivars_sysfs_list
30 * 2) ->ops calls
31 * 3) (un)registration of __efivars
32 */
33static DEFINE_SEMAPHORE(efivars_lock);
34
35static bool efivar_wq_enabled = true;
36DECLARE_WORK(efivar_work, NULL);
37EXPORT_SYMBOL_GPL(efivar_work);
38
39static bool
40validate_device_path(efi_char16_t *var_name, int match, u8 *buffer,
41 unsigned long len)
42{
43 struct efi_generic_dev_path *node;
44 int offset = 0;
45
46 node = (struct efi_generic_dev_path *)buffer;
47
48 if (len < sizeof(*node))
49 return false;
50
51 while (offset <= len - sizeof(*node) &&
52 node->length >= sizeof(*node) &&
53 node->length <= len - offset) {
54 offset += node->length;
55
56 if ((node->type == EFI_DEV_END_PATH ||
57 node->type == EFI_DEV_END_PATH2) &&
58 node->sub_type == EFI_DEV_END_ENTIRE)
59 return true;
60
61 node = (struct efi_generic_dev_path *)(buffer + offset);
62 }
63
64 /*
65 * If we're here then either node->length pointed past the end
66 * of the buffer or we reached the end of the buffer without
67 * finding a device path end node.
68 */
69 return false;
70}
71
72static bool
73validate_boot_order(efi_char16_t *var_name, int match, u8 *buffer,
74 unsigned long len)
75{
76 /* An array of 16-bit integers */
77 if ((len % 2) != 0)
78 return false;
79
80 return true;
81}
82
83static bool
84validate_load_option(efi_char16_t *var_name, int match, u8 *buffer,
85 unsigned long len)
86{
87 u16 filepathlength;
88 int i, desclength = 0, namelen;
89
90 namelen = ucs2_strnlen(var_name, EFI_VAR_NAME_LEN);
91
92 /* Either "Boot" or "Driver" followed by four digits of hex */
93 for (i = match; i < match+4; i++) {
94 if (var_name[i] > 127 ||
95 hex_to_bin(var_name[i] & 0xff) < 0)
96 return true;
97 }
98
99 /* Reject it if there's 4 digits of hex and then further content */
100 if (namelen > match + 4)
101 return false;
102
103 /* A valid entry must be at least 8 bytes */
104 if (len < 8)
105 return false;
106
107 filepathlength = buffer[4] | buffer[5] << 8;
108
109 /*
110 * There's no stored length for the description, so it has to be
111 * found by hand
112 */
113 desclength = ucs2_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2;
114
115 /* Each boot entry must have a descriptor */
116 if (!desclength)
117 return false;
118
119 /*
120 * If the sum of the length of the description, the claimed filepath
121 * length and the original header are greater than the length of the
122 * variable, it's malformed
123 */
124 if ((desclength + filepathlength + 6) > len)
125 return false;
126
127 /*
128 * And, finally, check the filepath
129 */
130 return validate_device_path(var_name, match, buffer + desclength + 6,
131 filepathlength);
132}
133
134static bool
135validate_uint16(efi_char16_t *var_name, int match, u8 *buffer,
136 unsigned long len)
137{
138 /* A single 16-bit integer */
139 if (len != 2)
140 return false;
141
142 return true;
143}
144
145static bool
146validate_ascii_string(efi_char16_t *var_name, int match, u8 *buffer,
147 unsigned long len)
148{
149 int i;
150
151 for (i = 0; i < len; i++) {
152 if (buffer[i] > 127)
153 return false;
154
155 if (buffer[i] == 0)
156 return true;
157 }
158
159 return false;
160}
161
162struct variable_validate {
163 efi_guid_t vendor;
164 char *name;
165 bool (*validate)(efi_char16_t *var_name, int match, u8 *data,
166 unsigned long len);
167};
168
169/*
170 * This is the list of variables we need to validate, as well as the
171 * whitelist for what we think is safe not to default to immutable.
172 *
173 * If it has a validate() method that's not NULL, it'll go into the
174 * validation routine. If not, it is assumed valid, but still used for
175 * whitelisting.
176 *
177 * Note that it's sorted by {vendor,name}, but globbed names must come after
178 * any other name with the same prefix.
179 */
180static const struct variable_validate variable_validate[] = {
181 { EFI_GLOBAL_VARIABLE_GUID, "BootNext", validate_uint16 },
182 { EFI_GLOBAL_VARIABLE_GUID, "BootOrder", validate_boot_order },
183 { EFI_GLOBAL_VARIABLE_GUID, "Boot*", validate_load_option },
184 { EFI_GLOBAL_VARIABLE_GUID, "DriverOrder", validate_boot_order },
185 { EFI_GLOBAL_VARIABLE_GUID, "Driver*", validate_load_option },
186 { EFI_GLOBAL_VARIABLE_GUID, "ConIn", validate_device_path },
187 { EFI_GLOBAL_VARIABLE_GUID, "ConInDev", validate_device_path },
188 { EFI_GLOBAL_VARIABLE_GUID, "ConOut", validate_device_path },
189 { EFI_GLOBAL_VARIABLE_GUID, "ConOutDev", validate_device_path },
190 { EFI_GLOBAL_VARIABLE_GUID, "ErrOut", validate_device_path },
191 { EFI_GLOBAL_VARIABLE_GUID, "ErrOutDev", validate_device_path },
192 { EFI_GLOBAL_VARIABLE_GUID, "Lang", validate_ascii_string },
193 { EFI_GLOBAL_VARIABLE_GUID, "OsIndications", NULL },
194 { EFI_GLOBAL_VARIABLE_GUID, "PlatformLang", validate_ascii_string },
195 { EFI_GLOBAL_VARIABLE_GUID, "Timeout", validate_uint16 },
196 { LINUX_EFI_CRASH_GUID, "*", NULL },
197 { NULL_GUID, "", NULL },
198};
199
200/*
201 * Check if @var_name matches the pattern given in @match_name.
202 *
203 * @var_name: an array of @len non-NUL characters.
204 * @match_name: a NUL-terminated pattern string, optionally ending in "*". A
205 * final "*" character matches any trailing characters @var_name,
206 * including the case when there are none left in @var_name.
207 * @match: on output, the number of non-wildcard characters in @match_name
208 * that @var_name matches, regardless of the return value.
209 * @return: whether @var_name fully matches @match_name.
210 */
211static bool
212variable_matches(const char *var_name, size_t len, const char *match_name,
213 int *match)
214{
215 for (*match = 0; ; (*match)++) {
216 char c = match_name[*match];
217
218 switch (c) {
219 case '*':
220 /* Wildcard in @match_name means we've matched. */
221 return true;
222
223 case '\0':
224 /* @match_name has ended. Has @var_name too? */
225 return (*match == len);
226
227 default:
228 /*
229 * We've reached a non-wildcard char in @match_name.
230 * Continue only if there's an identical character in
231 * @var_name.
232 */
233 if (*match < len && c == var_name[*match])
234 continue;
235 return false;
236 }
237 }
238}
239
240bool
241efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data,
242 unsigned long data_size)
243{
244 int i;
245 unsigned long utf8_size;
246 u8 *utf8_name;
247
248 utf8_size = ucs2_utf8size(var_name);
249 utf8_name = kmalloc(utf8_size + 1, GFP_KERNEL);
250 if (!utf8_name)
251 return false;
252
253 ucs2_as_utf8(utf8_name, var_name, utf8_size);
254 utf8_name[utf8_size] = '\0';
255
256 for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
257 const char *name = variable_validate[i].name;
258 int match = 0;
259
260 if (efi_guidcmp(vendor, variable_validate[i].vendor))
261 continue;
262
263 if (variable_matches(utf8_name, utf8_size+1, name, &match)) {
264 if (variable_validate[i].validate == NULL)
265 break;
266 kfree(utf8_name);
267 return variable_validate[i].validate(var_name, match,
268 data, data_size);
269 }
270 }
271 kfree(utf8_name);
272 return true;
273}
274EXPORT_SYMBOL_GPL(efivar_validate);
275
276bool
277efivar_variable_is_removable(efi_guid_t vendor, const char *var_name,
278 size_t len)
279{
280 int i;
281 bool found = false;
282 int match = 0;
283
284 /*
285 * Check if our variable is in the validated variables list
286 */
287 for (i = 0; variable_validate[i].name[0] != '\0'; i++) {
288 if (efi_guidcmp(variable_validate[i].vendor, vendor))
289 continue;
290
291 if (variable_matches(var_name, len,
292 variable_validate[i].name, &match)) {
293 found = true;
294 break;
295 }
296 }
297
298 /*
299 * If it's in our list, it is removable.
300 */
301 return found;
302}
303EXPORT_SYMBOL_GPL(efivar_variable_is_removable);
304
305static efi_status_t
306check_var_size(u32 attributes, unsigned long size)
307{
308 const struct efivar_operations *fops;
309
310 if (!__efivars)
311 return EFI_UNSUPPORTED;
312
313 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
321static efi_status_t
322check_var_size_nonblocking(u32 attributes, unsigned long size)
323{
324 const struct efivar_operations *fops;
325
326 if (!__efivars)
327 return EFI_UNSUPPORTED;
328
329 fops = __efivars->ops;
330
331 if (!fops->query_variable_store)
332 return EFI_UNSUPPORTED;
333
334 return fops->query_variable_store(attributes, size, true);
335}
336
337static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor,
338 struct list_head *head)
339{
340 struct efivar_entry *entry, *n;
341 unsigned long strsize1, strsize2;
342 bool found = false;
343
344 strsize1 = ucs2_strsize(variable_name, 1024);
345 list_for_each_entry_safe(entry, n, head, list) {
346 strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
347 if (strsize1 == strsize2 &&
348 !memcmp(variable_name, &(entry->var.VariableName),
349 strsize2) &&
350 !efi_guidcmp(entry->var.VendorGuid,
351 *vendor)) {
352 found = true;
353 break;
354 }
355 }
356 return found;
357}
358
359/*
360 * Returns the size of variable_name, in bytes, including the
361 * terminating NULL character, or variable_name_size if no NULL
362 * character is found among the first variable_name_size bytes.
363 */
364static unsigned long var_name_strnsize(efi_char16_t *variable_name,
365 unsigned long variable_name_size)
366{
367 unsigned long len;
368 efi_char16_t c;
369
370 /*
371 * The variable name is, by definition, a NULL-terminated
372 * string, so make absolutely sure that variable_name_size is
373 * the value we expect it to be. If not, return the real size.
374 */
375 for (len = 2; len <= variable_name_size; len += sizeof(c)) {
376 c = variable_name[(len / sizeof(c)) - 1];
377 if (!c)
378 break;
379 }
380
381 return min(len, variable_name_size);
382}
383
384/*
385 * Print a warning when duplicate EFI variables are encountered and
386 * disable the sysfs workqueue since the firmware is buggy.
387 */
388static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid,
389 unsigned long len16)
390{
391 size_t i, len8 = len16 / sizeof(efi_char16_t);
392 char *str8;
393
394 /*
395 * Disable the workqueue since the algorithm it uses for
396 * detecting new variables won't work with this buggy
397 * implementation of GetNextVariableName().
398 */
399 efivar_wq_enabled = false;
400
401 str8 = kzalloc(len8, GFP_KERNEL);
402 if (!str8)
403 return;
404
405 for (i = 0; i < len8; i++)
406 str8[i] = str16[i];
407
408 printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n",
409 str8, vendor_guid);
410 kfree(str8);
411}
412
413/**
414 * efivar_init - build the initial list of EFI variables
415 * @func: callback function to invoke for every variable
416 * @data: function-specific data to pass to @func
417 * @atomic: do we need to execute the @func-loop atomically?
418 * @duplicates: error if we encounter duplicates on @head?
419 * @head: initialised head of variable list
420 *
421 * Get every EFI variable from the firmware and invoke @func. @func
422 * should call efivar_entry_add() to build the list of variables.
423 *
424 * Returns 0 on success, or a kernel error code on failure.
425 */
426int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *),
427 void *data, bool duplicates, struct list_head *head)
428{
429 const struct efivar_operations *ops;
430 unsigned long variable_name_size = 1024;
431 efi_char16_t *variable_name;
432 efi_status_t status;
433 efi_guid_t vendor_guid;
434 int err = 0;
435
436 if (!__efivars)
437 return -EFAULT;
438
439 ops = __efivars->ops;
440
441 variable_name = kzalloc(variable_name_size, GFP_KERNEL);
442 if (!variable_name) {
443 printk(KERN_ERR "efivars: Memory allocation failed.\n");
444 return -ENOMEM;
445 }
446
447 if (down_interruptible(&efivars_lock)) {
448 err = -EINTR;
449 goto free;
450 }
451
452 /*
453 * Per EFI spec, the maximum storage allocated for both
454 * the variable name and variable data is 1024 bytes.
455 */
456
457 do {
458 variable_name_size = 1024;
459
460 status = ops->get_next_variable(&variable_name_size,
461 variable_name,
462 &vendor_guid);
463 switch (status) {
464 case EFI_SUCCESS:
465 if (duplicates)
466 up(&efivars_lock);
467
468 variable_name_size = var_name_strnsize(variable_name,
469 variable_name_size);
470
471 /*
472 * Some firmware implementations return the
473 * same variable name on multiple calls to
474 * get_next_variable(). Terminate the loop
475 * immediately as there is no guarantee that
476 * we'll ever see a different variable name,
477 * and may end up looping here forever.
478 */
479 if (duplicates &&
480 variable_is_present(variable_name, &vendor_guid,
481 head)) {
482 dup_variable_bug(variable_name, &vendor_guid,
483 variable_name_size);
484 status = EFI_NOT_FOUND;
485 } else {
486 err = func(variable_name, vendor_guid,
487 variable_name_size, data);
488 if (err)
489 status = EFI_NOT_FOUND;
490 }
491
492 if (duplicates) {
493 if (down_interruptible(&efivars_lock)) {
494 err = -EINTR;
495 goto free;
496 }
497 }
498
499 break;
500 case EFI_NOT_FOUND:
501 break;
502 default:
503 printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
504 status);
505 status = EFI_NOT_FOUND;
506 break;
507 }
508
509 } while (status != EFI_NOT_FOUND);
510
511 up(&efivars_lock);
512free:
513 kfree(variable_name);
514
515 return err;
516}
517EXPORT_SYMBOL_GPL(efivar_init);
518
519/**
520 * efivar_entry_add - add entry to variable list
521 * @entry: entry to add to list
522 * @head: list head
523 *
524 * Returns 0 on success, or a kernel error code on failure.
525 */
526int efivar_entry_add(struct efivar_entry *entry, struct list_head *head)
527{
528 if (down_interruptible(&efivars_lock))
529 return -EINTR;
530 list_add(&entry->list, head);
531 up(&efivars_lock);
532
533 return 0;
534}
535EXPORT_SYMBOL_GPL(efivar_entry_add);
536
537/**
538 * efivar_entry_remove - remove entry from variable list
539 * @entry: entry to remove from list
540 *
541 * Returns 0 on success, or a kernel error code on failure.
542 */
543int efivar_entry_remove(struct efivar_entry *entry)
544{
545 if (down_interruptible(&efivars_lock))
546 return -EINTR;
547 list_del(&entry->list);
548 up(&efivars_lock);
549
550 return 0;
551}
552EXPORT_SYMBOL_GPL(efivar_entry_remove);
553
554/*
555 * efivar_entry_list_del_unlock - remove entry from variable list
556 * @entry: entry to remove
557 *
558 * Remove @entry from the variable list and release the list lock.
559 *
560 * NOTE: slightly weird locking semantics here - we expect to be
561 * called with the efivars lock already held, and we release it before
562 * returning. This is because this function is usually called after
563 * set_variable() while the lock is still held.
564 */
565static void efivar_entry_list_del_unlock(struct efivar_entry *entry)
566{
567 list_del(&entry->list);
568 up(&efivars_lock);
569}
570
571/**
572 * __efivar_entry_delete - delete an EFI variable
573 * @entry: entry containing EFI variable to delete
574 *
575 * Delete the variable from the firmware but leave @entry on the
576 * variable list.
577 *
578 * This function differs from efivar_entry_delete() because it does
579 * not remove @entry from the variable list. Also, it is safe to be
580 * called from within a efivar_entry_iter_begin() and
581 * efivar_entry_iter_end() region, unlike efivar_entry_delete().
582 *
583 * Returns 0 on success, or a converted EFI status code if
584 * set_variable() fails.
585 */
586int __efivar_entry_delete(struct efivar_entry *entry)
587{
588 efi_status_t status;
589
590 if (!__efivars)
591 return -EINVAL;
592
593 status = __efivars->ops->set_variable(entry->var.VariableName,
594 &entry->var.VendorGuid,
595 0, 0, NULL);
596
597 return efi_status_to_err(status);
598}
599EXPORT_SYMBOL_GPL(__efivar_entry_delete);
600
601/**
602 * efivar_entry_delete - delete variable and remove entry from list
603 * @entry: entry containing variable to delete
604 *
605 * Delete the variable from the firmware and remove @entry from the
606 * variable list. It is the caller's responsibility to free @entry
607 * once we return.
608 *
609 * Returns 0 on success, -EINTR if we can't grab the semaphore,
610 * converted EFI status code if set_variable() fails.
611 */
612int efivar_entry_delete(struct efivar_entry *entry)
613{
614 const struct efivar_operations *ops;
615 efi_status_t status;
616
617 if (down_interruptible(&efivars_lock))
618 return -EINTR;
619
620 if (!__efivars) {
621 up(&efivars_lock);
622 return -EINVAL;
623 }
624 ops = __efivars->ops;
625 status = ops->set_variable(entry->var.VariableName,
626 &entry->var.VendorGuid,
627 0, 0, NULL);
628 if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND)) {
629 up(&efivars_lock);
630 return efi_status_to_err(status);
631 }
632
633 efivar_entry_list_del_unlock(entry);
634 return 0;
635}
636EXPORT_SYMBOL_GPL(efivar_entry_delete);
637
638/**
639 * efivar_entry_set - call set_variable()
640 * @entry: entry containing the EFI variable to write
641 * @attributes: variable attributes
642 * @size: size of @data buffer
643 * @data: buffer containing variable data
644 * @head: head of variable list
645 *
646 * Calls set_variable() for an EFI variable. If creating a new EFI
647 * variable, this function is usually followed by efivar_entry_add().
648 *
649 * Before writing the variable, the remaining EFI variable storage
650 * space is checked to ensure there is enough room available.
651 *
652 * If @head is not NULL a lookup is performed to determine whether
653 * the entry is already on the list.
654 *
655 * Returns 0 on success, -EINTR if we can't grab the semaphore,
656 * -EEXIST if a lookup is performed and the entry already exists on
657 * the list, or a converted EFI status code if set_variable() fails.
658 */
659int efivar_entry_set(struct efivar_entry *entry, u32 attributes,
660 unsigned long size, void *data, struct list_head *head)
661{
662 const struct efivar_operations *ops;
663 efi_status_t status;
664 efi_char16_t *name = entry->var.VariableName;
665 efi_guid_t vendor = entry->var.VendorGuid;
666
667 if (down_interruptible(&efivars_lock))
668 return -EINTR;
669
670 if (!__efivars) {
671 up(&efivars_lock);
672 return -EINVAL;
673 }
674 ops = __efivars->ops;
675 if (head && efivar_entry_find(name, vendor, head, false)) {
676 up(&efivars_lock);
677 return -EEXIST;
678 }
679
680 status = check_var_size(attributes, size + ucs2_strsize(name, 1024));
681 if (status == EFI_SUCCESS || status == EFI_UNSUPPORTED)
682 status = ops->set_variable(name, &vendor,
683 attributes, size, data);
684
685 up(&efivars_lock);
686
687 return efi_status_to_err(status);
688
689}
690EXPORT_SYMBOL_GPL(efivar_entry_set);
691
692/*
693 * efivar_entry_set_nonblocking - call set_variable_nonblocking()
694 *
695 * This function is guaranteed to not block and is suitable for calling
696 * from crash/panic handlers.
697 *
698 * Crucially, this function will not block if it cannot acquire
699 * efivars_lock. Instead, it returns -EBUSY.
700 */
701static int
702efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor,
703 u32 attributes, unsigned long size, void *data)
704{
705 const struct efivar_operations *ops;
706 efi_status_t status;
707
708 if (down_trylock(&efivars_lock))
709 return -EBUSY;
710
711 if (!__efivars) {
712 up(&efivars_lock);
713 return -EINVAL;
714 }
715
716 status = check_var_size_nonblocking(attributes,
717 size + ucs2_strsize(name, 1024));
718 if (status != EFI_SUCCESS) {
719 up(&efivars_lock);
720 return -ENOSPC;
721 }
722
723 ops = __efivars->ops;
724 status = ops->set_variable_nonblocking(name, &vendor, attributes,
725 size, data);
726
727 up(&efivars_lock);
728 return efi_status_to_err(status);
729}
730
731/**
732 * efivar_entry_set_safe - call set_variable() if enough space in firmware
733 * @name: buffer containing the variable name
734 * @vendor: variable vendor guid
735 * @attributes: variable attributes
736 * @block: can we block in this context?
737 * @size: size of @data buffer
738 * @data: buffer containing variable data
739 *
740 * Ensures there is enough free storage in the firmware for this variable, and
741 * if so, calls set_variable(). If creating a new EFI variable, this function
742 * is usually followed by efivar_entry_add().
743 *
744 * Returns 0 on success, -ENOSPC if the firmware does not have enough
745 * space for set_variable() to succeed, or a converted EFI status code
746 * if set_variable() fails.
747 */
748int efivar_entry_set_safe(efi_char16_t *name, efi_guid_t vendor, u32 attributes,
749 bool block, unsigned long size, void *data)
750{
751 const struct efivar_operations *ops;
752 efi_status_t status;
753
754 if (!__efivars)
755 return -EINVAL;
756
757 ops = __efivars->ops;
758 if (!ops->query_variable_store)
759 return -ENOSYS;
760
761 /*
762 * If the EFI variable backend provides a non-blocking
763 * ->set_variable() operation and we're in a context where we
764 * cannot block, then we need to use it to avoid live-locks,
765 * since the implication is that the regular ->set_variable()
766 * will block.
767 *
768 * If no ->set_variable_nonblocking() is provided then
769 * ->set_variable() is assumed to be non-blocking.
770 */
771 if (!block && ops->set_variable_nonblocking)
772 return efivar_entry_set_nonblocking(name, vendor, attributes,
773 size, data);
774
775 if (!block) {
776 if (down_trylock(&efivars_lock))
777 return -EBUSY;
778 } else {
779 if (down_interruptible(&efivars_lock))
780 return -EINTR;
781 }
782
783 status = check_var_size(attributes, size + ucs2_strsize(name, 1024));
784 if (status != EFI_SUCCESS) {
785 up(&efivars_lock);
786 return -ENOSPC;
787 }
788
789 status = ops->set_variable(name, &vendor, attributes, size, data);
790
791 up(&efivars_lock);
792
793 return efi_status_to_err(status);
794}
795EXPORT_SYMBOL_GPL(efivar_entry_set_safe);
796
797/**
798 * efivar_entry_find - search for an entry
799 * @name: the EFI variable name
800 * @guid: the EFI variable vendor's guid
801 * @head: head of the variable list
802 * @remove: should we remove the entry from the list?
803 *
804 * Search for an entry on the variable list that has the EFI variable
805 * name @name and vendor guid @guid. If an entry is found on the list
806 * and @remove is true, the entry is removed from the list.
807 *
808 * The caller MUST call efivar_entry_iter_begin() and
809 * efivar_entry_iter_end() before and after the invocation of this
810 * function, respectively.
811 *
812 * Returns the entry if found on the list, %NULL otherwise.
813 */
814struct efivar_entry *efivar_entry_find(efi_char16_t *name, efi_guid_t guid,
815 struct list_head *head, bool remove)
816{
817 struct efivar_entry *entry, *n;
818 int strsize1, strsize2;
819 bool found = false;
820
821 list_for_each_entry_safe(entry, n, head, list) {
822 strsize1 = ucs2_strsize(name, 1024);
823 strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
824 if (strsize1 == strsize2 &&
825 !memcmp(name, &(entry->var.VariableName), strsize1) &&
826 !efi_guidcmp(guid, entry->var.VendorGuid)) {
827 found = true;
828 break;
829 }
830 }
831
832 if (!found)
833 return NULL;
834
835 if (remove) {
836 if (entry->scanning) {
837 /*
838 * The entry will be deleted
839 * after scanning is completed.
840 */
841 entry->deleting = true;
842 } else
843 list_del(&entry->list);
844 }
845
846 return entry;
847}
848EXPORT_SYMBOL_GPL(efivar_entry_find);
849
850/**
851 * efivar_entry_size - obtain the size of a variable
852 * @entry: entry for this variable
853 * @size: location to store the variable's size
854 */
855int efivar_entry_size(struct efivar_entry *entry, unsigned long *size)
856{
857 const struct efivar_operations *ops;
858 efi_status_t status;
859
860 *size = 0;
861
862 if (down_interruptible(&efivars_lock))
863 return -EINTR;
864 if (!__efivars) {
865 up(&efivars_lock);
866 return -EINVAL;
867 }
868 ops = __efivars->ops;
869 status = ops->get_variable(entry->var.VariableName,
870 &entry->var.VendorGuid, NULL, size, NULL);
871 up(&efivars_lock);
872
873 if (status != EFI_BUFFER_TOO_SMALL)
874 return efi_status_to_err(status);
875
876 return 0;
877}
878EXPORT_SYMBOL_GPL(efivar_entry_size);
879
880/**
881 * __efivar_entry_get - call get_variable()
882 * @entry: read data for this variable
883 * @attributes: variable attributes
884 * @size: size of @data buffer
885 * @data: buffer to store variable data
886 *
887 * The caller MUST call efivar_entry_iter_begin() and
888 * efivar_entry_iter_end() before and after the invocation of this
889 * function, respectively.
890 */
891int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
892 unsigned long *size, void *data)
893{
894 efi_status_t status;
895
896 if (!__efivars)
897 return -EINVAL;
898
899 status = __efivars->ops->get_variable(entry->var.VariableName,
900 &entry->var.VendorGuid,
901 attributes, size, data);
902
903 return efi_status_to_err(status);
904}
905EXPORT_SYMBOL_GPL(__efivar_entry_get);
906
907/**
908 * efivar_entry_get - call get_variable()
909 * @entry: read data for this variable
910 * @attributes: variable attributes
911 * @size: size of @data buffer
912 * @data: buffer to store variable data
913 */
914int efivar_entry_get(struct efivar_entry *entry, u32 *attributes,
915 unsigned long *size, void *data)
916{
917 efi_status_t status;
918
919 if (down_interruptible(&efivars_lock))
920 return -EINTR;
921
922 if (!__efivars) {
923 up(&efivars_lock);
924 return -EINVAL;
925 }
926
927 status = __efivars->ops->get_variable(entry->var.VariableName,
928 &entry->var.VendorGuid,
929 attributes, size, data);
930 up(&efivars_lock);
931
932 return efi_status_to_err(status);
933}
934EXPORT_SYMBOL_GPL(efivar_entry_get);
935
936/**
937 * efivar_entry_set_get_size - call set_variable() and get new size (atomic)
938 * @entry: entry containing variable to set and get
939 * @attributes: attributes of variable to be written
940 * @size: size of data buffer
941 * @data: buffer containing data to write
942 * @set: did the set_variable() call succeed?
943 *
944 * This is a pretty special (complex) function. See efivarfs_file_write().
945 *
946 * Atomically call set_variable() for @entry and if the call is
947 * successful, return the new size of the variable from get_variable()
948 * in @size. The success of set_variable() is indicated by @set.
949 *
950 * Returns 0 on success, -EINVAL if the variable data is invalid,
951 * -ENOSPC if the firmware does not have enough available space, or a
952 * converted EFI status code if either of set_variable() or
953 * get_variable() fail.
954 *
955 * If the EFI variable does not exist when calling set_variable()
956 * (EFI_NOT_FOUND), @entry is removed from the variable list.
957 */
958int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes,
959 unsigned long *size, void *data, bool *set)
960{
961 const struct efivar_operations *ops;
962 efi_char16_t *name = entry->var.VariableName;
963 efi_guid_t *vendor = &entry->var.VendorGuid;
964 efi_status_t status;
965 int err;
966
967 *set = false;
968
969 if (efivar_validate(*vendor, name, data, *size) == false)
970 return -EINVAL;
971
972 /*
973 * The lock here protects the get_variable call, the conditional
974 * set_variable call, and removal of the variable from the efivars
975 * list (in the case of an authenticated delete).
976 */
977 if (down_interruptible(&efivars_lock))
978 return -EINTR;
979
980 if (!__efivars) {
981 err = -EINVAL;
982 goto out;
983 }
984
985 /*
986 * Ensure that the available space hasn't shrunk below the safe level
987 */
988 status = check_var_size(attributes, *size + ucs2_strsize(name, 1024));
989 if (status != EFI_SUCCESS) {
990 if (status != EFI_UNSUPPORTED) {
991 err = efi_status_to_err(status);
992 goto out;
993 }
994
995 if (*size > 65536) {
996 err = -ENOSPC;
997 goto out;
998 }
999 }
1000
1001 ops = __efivars->ops;
1002
1003 status = ops->set_variable(name, vendor, attributes, *size, data);
1004 if (status != EFI_SUCCESS) {
1005 err = efi_status_to_err(status);
1006 goto out;
1007 }
1008
1009 *set = true;
1010
1011 /*
1012 * Writing to the variable may have caused a change in size (which
1013 * could either be an append or an overwrite), or the variable to be
1014 * deleted. Perform a GetVariable() so we can tell what actually
1015 * happened.
1016 */
1017 *size = 0;
1018 status = ops->get_variable(entry->var.VariableName,
1019 &entry->var.VendorGuid,
1020 NULL, size, NULL);
1021
1022 if (status == EFI_NOT_FOUND)
1023 efivar_entry_list_del_unlock(entry);
1024 else
1025 up(&efivars_lock);
1026
1027 if (status && status != EFI_BUFFER_TOO_SMALL)
1028 return efi_status_to_err(status);
1029
1030 return 0;
1031
1032out:
1033 up(&efivars_lock);
1034 return err;
1035
1036}
1037EXPORT_SYMBOL_GPL(efivar_entry_set_get_size);
1038
1039/**
1040 * efivar_entry_iter_begin - begin iterating the variable list
1041 *
1042 * Lock the variable list to prevent entry insertion and removal until
1043 * efivar_entry_iter_end() is called. This function is usually used in
1044 * conjunction with __efivar_entry_iter() or efivar_entry_iter().
1045 */
1046int efivar_entry_iter_begin(void)
1047{
1048 return down_interruptible(&efivars_lock);
1049}
1050EXPORT_SYMBOL_GPL(efivar_entry_iter_begin);
1051
1052/**
1053 * efivar_entry_iter_end - finish iterating the variable list
1054 *
1055 * Unlock the variable list and allow modifications to the list again.
1056 */
1057void efivar_entry_iter_end(void)
1058{
1059 up(&efivars_lock);
1060}
1061EXPORT_SYMBOL_GPL(efivar_entry_iter_end);
1062
1063/**
1064 * __efivar_entry_iter - iterate over variable list
1065 * @func: callback function
1066 * @head: head of the variable list
1067 * @data: function-specific data to pass to callback
1068 * @prev: entry to begin iterating from
1069 *
1070 * Iterate over the list of EFI variables and call @func with every
1071 * entry on the list. It is safe for @func to remove entries in the
1072 * list via efivar_entry_delete().
1073 *
1074 * You MUST call efivar_entry_iter_begin() before this function, and
1075 * efivar_entry_iter_end() afterwards.
1076 *
1077 * It is possible to begin iteration from an arbitrary entry within
1078 * the list by passing @prev. @prev is updated on return to point to
1079 * the last entry passed to @func. To begin iterating from the
1080 * beginning of the list @prev must be %NULL.
1081 *
1082 * The restrictions for @func are the same as documented for
1083 * efivar_entry_iter().
1084 */
1085int __efivar_entry_iter(int (*func)(struct efivar_entry *, void *),
1086 struct list_head *head, void *data,
1087 struct efivar_entry **prev)
1088{
1089 struct efivar_entry *entry, *n;
1090 int err = 0;
1091
1092 if (!prev || !*prev) {
1093 list_for_each_entry_safe(entry, n, head, list) {
1094 err = func(entry, data);
1095 if (err)
1096 break;
1097 }
1098
1099 if (prev)
1100 *prev = entry;
1101
1102 return err;
1103 }
1104
1105
1106 list_for_each_entry_safe_continue((*prev), n, head, list) {
1107 err = func(*prev, data);
1108 if (err)
1109 break;
1110 }
1111
1112 return err;
1113}
1114EXPORT_SYMBOL_GPL(__efivar_entry_iter);
1115
1116/**
1117 * efivar_entry_iter - iterate over variable list
1118 * @func: callback function
1119 * @head: head of variable list
1120 * @data: function-specific data to pass to callback
1121 *
1122 * Iterate over the list of EFI variables and call @func with every
1123 * entry on the list. It is safe for @func to remove entries in the
1124 * list via efivar_entry_delete() while iterating.
1125 *
1126 * Some notes for the callback function:
1127 * - a non-zero return value indicates an error and terminates the loop
1128 * - @func is called from atomic context
1129 */
1130int efivar_entry_iter(int (*func)(struct efivar_entry *, void *),
1131 struct list_head *head, void *data)
1132{
1133 int err = 0;
1134
1135 err = efivar_entry_iter_begin();
1136 if (err)
1137 return err;
1138 err = __efivar_entry_iter(func, head, data, NULL);
1139 efivar_entry_iter_end();
1140
1141 return err;
1142}
1143EXPORT_SYMBOL_GPL(efivar_entry_iter);
1144
1145/**
1146 * efivars_kobject - get the kobject for the registered efivars
1147 *
1148 * If efivars_register() has not been called we return NULL,
1149 * otherwise return the kobject used at registration time.
1150 */
1151struct kobject *efivars_kobject(void)
1152{
1153 if (!__efivars)
1154 return NULL;
1155
1156 return __efivars->kobject;
1157}
1158EXPORT_SYMBOL_GPL(efivars_kobject);
1159
1160/**
1161 * efivar_run_worker - schedule the efivar worker thread
1162 */
1163void efivar_run_worker(void)
1164{
1165 if (efivar_wq_enabled)
1166 schedule_work(&efivar_work);
1167}
1168EXPORT_SYMBOL_GPL(efivar_run_worker);
1169
1170/**
1171 * efivars_register - register an efivars
1172 * @efivars: efivars to register
1173 * @ops: efivars operations
1174 * @kobject: @efivars-specific kobject
1175 *
1176 * Only a single efivars can be registered at any time.
1177 */
1178int efivars_register(struct efivars *efivars,
1179 const struct efivar_operations *ops,
1180 struct kobject *kobject)
1181{
1182 if (down_interruptible(&efivars_lock))
1183 return -EINTR;
1184
1185 efivars->ops = ops;
1186 efivars->kobject = kobject;
1187
1188 __efivars = efivars;
1189
1190 pr_info("Registered efivars operations\n");
1191
1192 up(&efivars_lock);
1193
1194 return 0;
1195}
1196EXPORT_SYMBOL_GPL(efivars_register);
1197
1198/**
1199 * efivars_unregister - unregister an efivars
1200 * @efivars: efivars to unregister
1201 *
1202 * The caller must have already removed every entry from the list,
1203 * failure to do so is an error.
1204 */
1205int efivars_unregister(struct efivars *efivars)
1206{
1207 int rv;
1208
1209 if (down_interruptible(&efivars_lock))
1210 return -EINTR;
1211
1212 if (!__efivars) {
1213 printk(KERN_ERR "efivars not registered\n");
1214 rv = -EINVAL;
1215 goto out;
1216 }
1217
1218 if (__efivars != efivars) {
1219 rv = -EINVAL;
1220 goto out;
1221 }
1222
1223 pr_info("Unregistered efivars operations\n");
1224 __efivars = NULL;
1225
1226 rv = 0;
1227out:
1228 up(&efivars_lock);
1229 return rv;
1230}
1231EXPORT_SYMBOL_GPL(efivars_unregister);
1232
1233int efivar_supports_writes(void)
1234{
1235 return __efivars && __efivars->ops->set_variable;
1236}
1237EXPORT_SYMBOL_GPL(efivar_supports_writes);