aboutsummaryrefslogtreecommitdiff
path: root/lib/efi_loader/efi_variable.c
blob: 39a848290380f53410d515ff30a36a250c5f15bc (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
// SPDX-License-Identifier: GPL-2.0+
/*
 * UEFI runtime variable services
 *
 * Copyright (c) 2017 Rob Clark
 */

#define LOG_CATEGORY LOGC_EFI

#include <common.h>
#include <efi_loader.h>
#include <efi_variable.h>
#include <env.h>
#include <env_internal.h>
#include <hexdump.h>
#include <log.h>
#include <malloc.h>
#include <rtc.h>
#include <search.h>
#include <uuid.h>
#include <crypto/pkcs7_parser.h>
#include <linux/compat.h>
#include <u-boot/crc.h>
#include <asm/sections.h>

#ifdef CONFIG_EFI_SECURE_BOOT
static u8 pkcs7_hdr[] = {
	/* SEQUENCE */
	0x30, 0x82, 0x05, 0xc7,
	/* OID: pkcs7-signedData */
	0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x07, 0x02,
	/* Context Structured? */
	0xa0, 0x82, 0x05, 0xb8,
};

/**
 * efi_variable_parse_signature - parse a signature in variable
 * @buf:	Pointer to variable's value
 * @buflen:	Length of @buf
 *
 * Parse a signature embedded in variable's value and instantiate
 * a pkcs7_message structure. Since pkcs7_parse_message() accepts only
 * pkcs7's signedData, some header needed be prepended for correctly
 * parsing authentication data, particularly for variable's.
 *
 * Return:	Pointer to pkcs7_message structure on success, NULL on error
 */
static struct pkcs7_message *efi_variable_parse_signature(const void *buf,
							  size_t buflen)
{
	u8 *ebuf;
	size_t ebuflen, len;
	struct pkcs7_message *msg;

	/*
	 * This is the best assumption to check if the binary is
	 * already in a form of pkcs7's signedData.
	 */
	if (buflen > sizeof(pkcs7_hdr) &&
	    !memcmp(&((u8 *)buf)[4], &pkcs7_hdr[4], 11)) {
		msg = pkcs7_parse_message(buf, buflen);
		goto out;
	}

	/*
	 * Otherwise, we should add a dummy prefix sequence for pkcs7
	 * message parser to be able to process.
	 * NOTE: EDK2 also uses similar hack in WrapPkcs7Data()
	 * in CryptoPkg/Library/BaseCryptLib/Pk/CryptPkcs7VerifyCommon.c
	 * TODO:
	 * The header should be composed in a more refined manner.
	 */
	EFI_PRINT("Makeshift prefix added to authentication data\n");
	ebuflen = sizeof(pkcs7_hdr) + buflen;
	if (ebuflen <= 0x7f) {
		EFI_PRINT("Data is too short\n");
		return NULL;
	}

	ebuf = malloc(ebuflen);
	if (!ebuf) {
		EFI_PRINT("Out of memory\n");
		return NULL;
	}

	memcpy(ebuf, pkcs7_hdr, sizeof(pkcs7_hdr));
	memcpy(ebuf + sizeof(pkcs7_hdr), buf, buflen);
	len = ebuflen - 4;
	ebuf[2] = (len >> 8) & 0xff;
	ebuf[3] = len & 0xff;
	len = ebuflen - 0x13;
	ebuf[0x11] = (len >> 8) & 0xff;
	ebuf[0x12] = len & 0xff;

	msg = pkcs7_parse_message(ebuf, ebuflen);

	free(ebuf);

out:
	if (IS_ERR(msg))
		return NULL;

	return msg;
}

/**
 * efi_variable_authenticate - authenticate a variable
 * @variable:	Variable name in u16
 * @vendor:	Guid of variable
 * @data_size:	Size of @data
 * @data:	Pointer to variable's value
 * @given_attr:	Attributes to be given at SetVariable()
 * @env_attr:	Attributes that an existing variable holds
 * @time:	signed time that an existing variable holds
 *
 * Called by efi_set_variable() to verify that the input is correct.
 * Will replace the given data pointer with another that points to
 * the actual data to store in the internal memory.
 * On success, @data and @data_size will be replaced with variable's
 * actual data, excluding authentication data, and its size, and variable's
 * attributes and signed time will also be returned in @env_attr and @time,
 * respectively.
 *
 * Return:	status code
 */
static efi_status_t efi_variable_authenticate(u16 *variable,
					      const efi_guid_t *vendor,
					      efi_uintn_t *data_size,
					      const void **data, u32 given_attr,
					      u32 *env_attr, u64 *time)
{
	const struct efi_variable_authentication_2 *auth;
	struct efi_signature_store *truststore, *truststore2;
	struct pkcs7_message *var_sig;
	struct efi_image_regions *regs;
	struct efi_time timestamp;
	struct rtc_time tm;
	u64 new_time;
	enum efi_auth_var_type var_type;
	efi_status_t ret;

	var_sig = NULL;
	truststore = NULL;
	truststore2 = NULL;
	regs = NULL;
	ret = EFI_SECURITY_VIOLATION;

	if (*data_size < sizeof(struct efi_variable_authentication_2))
		goto err;

	/* authentication data */
	auth = *data;
	if (*data_size < (sizeof(auth->time_stamp)
				+ auth->auth_info.hdr.dwLength))
		goto err;

	if (guidcmp(&auth->auth_info.cert_type, &efi_guid_cert_type_pkcs7))
		goto err;

	memcpy(&timestamp, &auth->time_stamp, sizeof(timestamp));
	if (timestamp.pad1 || timestamp.nanosecond || timestamp.timezone ||
	    timestamp.daylight || timestamp.pad2)
		goto err;

	*data += sizeof(auth->time_stamp) + auth->auth_info.hdr.dwLength;
	*data_size -= (sizeof(auth->time_stamp)
				+ auth->auth_info.hdr.dwLength);

	memset(&tm, 0, sizeof(tm));
	tm.tm_year = timestamp.year;
	tm.tm_mon = timestamp.month;
	tm.tm_mday = timestamp.day;
	tm.tm_hour = timestamp.hour;
	tm.tm_min = timestamp.minute;
	tm.tm_sec = timestamp.second;
	new_time = rtc_mktime(&tm);

	if (!efi_secure_boot_enabled()) {
		/* finished checking */
		*time = new_time;
		return EFI_SUCCESS;
	}

	if (new_time <= *time)
		goto err;

	/* data to be digested */
	regs = calloc(sizeof(*regs) + sizeof(struct image_region) * 5, 1);
	if (!regs)
		goto err;
	regs->max = 5;
	efi_image_region_add(regs, (uint8_t *)variable,
			     (uint8_t *)variable
				+ u16_strlen(variable) * sizeof(u16), 1);
	efi_image_region_add(regs, (uint8_t *)vendor,
			     (uint8_t *)vendor + sizeof(*vendor), 1);
	efi_image_region_add(regs, (uint8_t *)&given_attr,
			     (uint8_t *)&given_attr + sizeof(given_attr), 1);
	efi_image_region_add(regs, (uint8_t *)&timestamp,
			     (uint8_t *)&timestamp + sizeof(timestamp), 1);
	efi_image_region_add(regs, (uint8_t *)*data,
			     (uint8_t *)*data + *data_size, 1);

	/* variable's signature list */
	if (auth->auth_info.hdr.dwLength < sizeof(auth->auth_info))
		goto err;
	var_sig = efi_variable_parse_signature(auth->auth_info.cert_data,
					       auth->auth_info.hdr.dwLength
						   - sizeof(auth->auth_info));
	if (!var_sig) {
		EFI_PRINT("Parsing variable's signature failed\n");
		goto err;
	}

	/* signature database used for authentication */
	var_type = efi_auth_var_get_type(variable, vendor);
	switch (var_type) {
	case EFI_AUTH_VAR_PK:
	case EFI_AUTH_VAR_KEK:
		/* with PK */
		truststore = efi_sigstore_parse_sigdb(L"PK");
		if (!truststore)
			goto err;
		break;
	case EFI_AUTH_VAR_DB:
	case EFI_AUTH_VAR_DBX:
		/* with PK and KEK */
		truststore = efi_sigstore_parse_sigdb(L"KEK");
		truststore2 = efi_sigstore_parse_sigdb(L"PK");
		if (!truststore) {
			if (!truststore2)
				goto err;

			truststore = truststore2;
			truststore2 = NULL;
		}
		break;
	default:
		/* TODO: support private authenticated variables */
		goto err;
	}

	/* verify signature */
	if (efi_signature_verify_with_sigdb(regs, var_sig, truststore, NULL)) {
		EFI_PRINT("Verified\n");
	} else {
		if (truststore2 &&
		    efi_signature_verify_with_sigdb(regs, var_sig,
						    truststore2, NULL)) {
			EFI_PRINT("Verified\n");
		} else {
			EFI_PRINT("Verifying variable's signature failed\n");
			goto err;
		}
	}

	/* finished checking */
	*time = new_time;
	ret = EFI_SUCCESS;

err:
	efi_sigstore_free(truststore);
	efi_sigstore_free(truststore2);
	pkcs7_free_message(var_sig);
	free(regs);

	return ret;
}
#else
static efi_status_t efi_variable_authenticate(u16 *variable,
					      const efi_guid_t *vendor,
					      efi_uintn_t *data_size,
					      const void **data, u32 given_attr,
					      u32 *env_attr, u64 *time)
{
	return EFI_SUCCESS;
}
#endif /* CONFIG_EFI_SECURE_BOOT */

efi_status_t __efi_runtime
efi_get_variable_int(u16 *variable_name, const efi_guid_t *vendor,
		     u32 *attributes, efi_uintn_t *data_size, void *data,
		     u64 *timep)
{
	efi_uintn_t old_size;
	struct efi_var_entry *var;
	u16 *pdata;

	if (!variable_name || !vendor || !data_size)
		return EFI_INVALID_PARAMETER;
	var = efi_var_mem_find(vendor, variable_name, NULL);
	if (!var)
		return EFI_NOT_FOUND;

	if (attributes)
		*attributes = var->attr;
	if (timep)
		*timep = var->time;

	old_size = *data_size;
	*data_size = var->length;
	if (old_size < var->length)
		return EFI_BUFFER_TOO_SMALL;

	if (!data)
		return EFI_INVALID_PARAMETER;

	for (pdata = var->name; *pdata; ++pdata)
		;
	++pdata;

	efi_memcpy_runtime(data, pdata, var->length);

	return EFI_SUCCESS;
}

efi_status_t __efi_runtime
efi_get_next_variable_name_int(efi_uintn_t *variable_name_size,
			       u16 *variable_name, efi_guid_t *vendor)
{
	struct efi_var_entry *var;
	efi_uintn_t old_size;
	u16 *pdata;

	if (!variable_name_size || !variable_name || !vendor)
		return EFI_INVALID_PARAMETER;

	efi_var_mem_find(vendor, variable_name, &var);

	if (!var)
		return EFI_NOT_FOUND;

	for (pdata = var->name; *pdata; ++pdata)
		;
	++pdata;

	old_size = *variable_name_size;
	*variable_name_size = (uintptr_t)pdata - (uintptr_t)var->name;

	if (old_size < *variable_name_size)
		return EFI_BUFFER_TOO_SMALL;

	efi_memcpy_runtime(variable_name, var->name, *variable_name_size);
	efi_memcpy_runtime(vendor, &var->guid, sizeof(efi_guid_t));

	return EFI_SUCCESS;
}

efi_status_t efi_set_variable_int(u16 *variable_name, const efi_guid_t *vendor,
				  u32 attributes, efi_uintn_t data_size,
				  const void *data, bool ro_check)
{
	struct efi_var_entry *var;
	efi_uintn_t ret;
	bool append, delete;
	u64 time = 0;
	enum efi_auth_var_type var_type;

	if (!variable_name || !*variable_name || !vendor ||
	    ((attributes & EFI_VARIABLE_RUNTIME_ACCESS) &&
	     !(attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)))
		return EFI_INVALID_PARAMETER;

	/* check if a variable exists */
	var = efi_var_mem_find(vendor, variable_name, NULL);
	append = !!(attributes & EFI_VARIABLE_APPEND_WRITE);
	attributes &= ~(u32)EFI_VARIABLE_APPEND_WRITE;
	delete = !append && (!data_size || !attributes);

	/* check attributes */
	var_type = efi_auth_var_get_type(variable_name, vendor);
	if (var) {
		if (ro_check && (var->attr & EFI_VARIABLE_READ_ONLY))
			return EFI_WRITE_PROTECTED;

		if (IS_ENABLED(CONFIG_EFI_VARIABLES_PRESEED)) {
			if (var_type != EFI_AUTH_VAR_NONE)
				return EFI_WRITE_PROTECTED;
		}

		/* attributes won't be changed */
		if (!delete &&
		    ((ro_check && var->attr != attributes) ||
		     (!ro_check && ((var->attr & ~(u32)EFI_VARIABLE_READ_ONLY)
				    != (attributes & ~(u32)EFI_VARIABLE_READ_ONLY))))) {
			return EFI_INVALID_PARAMETER;
		}
		time = var->time;
	} else {
		if (delete || append)
			/*
			 * Trying to delete or to update a non-existent
			 * variable.
			 */
			return EFI_NOT_FOUND;
	}

	if (var_type != EFI_AUTH_VAR_NONE) {
		/* authentication is mandatory */
		if (!(attributes &
		      EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)) {
			EFI_PRINT("%ls: TIME_BASED_AUTHENTICATED_WRITE_ACCESS required\n",
				  variable_name);
			return EFI_INVALID_PARAMETER;
		}
	}

	/* authenticate a variable */
	if (IS_ENABLED(CONFIG_EFI_SECURE_BOOT)) {
		if (attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS)
			return EFI_INVALID_PARAMETER;
		if (attributes &
		    EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS) {
			u32 env_attr;

			ret = efi_variable_authenticate(variable_name, vendor,
							&data_size, &data,
							attributes, &env_attr,
							&time);
			if (ret != EFI_SUCCESS)
				return ret;

			/* last chance to check for delete */
			if (!data_size)
				delete = true;
		}
	} else {
		if (attributes &
		    (EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS |
		     EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)) {
			EFI_PRINT("Secure boot is not configured\n");
			return EFI_INVALID_PARAMETER;
		}
	}

	if (delete) {
		/* EFI_NOT_FOUND has been handled before */
		ret = EFI_SUCCESS;
	} else if (append) {
		u16 *old_data = var->name;

		for (; *old_data; ++old_data)
			;
		++old_data;
		ret = efi_var_mem_ins(variable_name, vendor, attributes,
				      var->length, old_data, data_size, data,
				      time);
	} else {
		ret = efi_var_mem_ins(variable_name, vendor, attributes,
				      data_size, data, 0, NULL, time);
	}
	efi_var_mem_del(var);

	if (ret != EFI_SUCCESS)
		return ret;

	if (var_type == EFI_AUTH_VAR_PK)
		ret = efi_init_secure_state();
	else
		ret = EFI_SUCCESS;

	/* Write non-volatile EFI variables to file */
	if (attributes & EFI_VARIABLE_NON_VOLATILE &&
	    ret == EFI_SUCCESS && efi_obj_list_initialized == EFI_SUCCESS)
		efi_var_to_file();

	return EFI_SUCCESS;
}

efi_status_t efi_query_variable_info_int(u32 attributes,
					 u64 *maximum_variable_storage_size,
					 u64 *remaining_variable_storage_size,
					 u64 *maximum_variable_size)
{
	*maximum_variable_storage_size = EFI_VAR_BUF_SIZE -
					 sizeof(struct efi_var_file);
	*remaining_variable_storage_size = efi_var_mem_free();
	*maximum_variable_size = EFI_VAR_BUF_SIZE -
				 sizeof(struct efi_var_file) -
				 sizeof(struct efi_var_entry);
	return EFI_SUCCESS;
}

/**
 * efi_query_variable_info_runtime() - runtime implementation of
 *				       QueryVariableInfo()
 *
 * @attributes:				bitmask to select variables to be
 *					queried
 * @maximum_variable_storage_size:	maximum size of storage area for the
 *					selected variable types
 * @remaining_variable_storage_size:	remaining size of storage are for the
 *					selected variable types
 * @maximum_variable_size:		maximum size of a variable of the
 *					selected type
 * Returns:				status code
 */
efi_status_t __efi_runtime EFIAPI efi_query_variable_info_runtime(
			u32 attributes,
			u64 *maximum_variable_storage_size,
			u64 *remaining_variable_storage_size,
			u64 *maximum_variable_size)
{
	return EFI_UNSUPPORTED;
}

/**
 * efi_get_variable_runtime() - runtime implementation of GetVariable()
 *
 * @variable_name:	name of the variable
 * @vendor:		vendor GUID
 * @attributes:		attributes of the variable
 * @data_size:		size of the buffer to which the variable value is copied
 * @data:		buffer to which the variable value is copied
 * Return:		status code
 */
static efi_status_t __efi_runtime EFIAPI
efi_get_variable_runtime(u16 *variable_name, const efi_guid_t *vendor,
			 u32 *attributes, efi_uintn_t *data_size, void *data)
{
	efi_status_t ret;

	ret = efi_get_variable_int(variable_name, vendor, attributes,
				   data_size, data, NULL);

	/* Remove EFI_VARIABLE_READ_ONLY flag */
	if (attributes)
		*attributes &= EFI_VARIABLE_MASK;

	return ret;
}

/**
 * efi_get_next_variable_name_runtime() - runtime implementation of
 *					  GetNextVariable()
 *
 * @variable_name_size:	size of variable_name buffer in byte
 * @variable_name:	name of uefi variable's name in u16
 * @vendor:		vendor's guid
 * Return: status code
 */
static efi_status_t __efi_runtime EFIAPI
efi_get_next_variable_name_runtime(efi_uintn_t *variable_name_size,
				   u16 *variable_name, efi_guid_t *vendor)
{
	return efi_get_next_variable_name_int(variable_name_size, variable_name,
					      vendor);
}

/**
 * efi_set_variable_runtime() - runtime implementation of SetVariable()
 *
 * @variable_name:	name of the variable
 * @vendor:		vendor GUID
 * @attributes:		attributes of the variable
 * @data_size:		size of the buffer with the variable value
 * @data:		buffer with the variable value
 * Return:		status code
 */
static efi_status_t __efi_runtime EFIAPI
efi_set_variable_runtime(u16 *variable_name, const efi_guid_t *vendor,
			 u32 attributes, efi_uintn_t data_size,
			 const void *data)
{
	return EFI_UNSUPPORTED;
}

/**
 * efi_variables_boot_exit_notify() - notify ExitBootServices() is called
 */
void efi_variables_boot_exit_notify(void)
{
	/* Switch variable services functions to runtime version */
	efi_runtime_services.get_variable = efi_get_variable_runtime;
	efi_runtime_services.get_next_variable_name =
				efi_get_next_variable_name_runtime;
	efi_runtime_services.set_variable = efi_set_variable_runtime;
	efi_runtime_services.query_variable_info =
				efi_query_variable_info_runtime;
	efi_update_table_header_crc32(&efi_runtime_services.hdr);
}

/**
 * efi_init_variables() - initialize variable services
 *
 * Return:	status code
 */
efi_status_t efi_init_variables(void)
{
	efi_status_t ret;

	ret = efi_var_mem_init();
	if (ret != EFI_SUCCESS)
		return ret;

	ret = efi_init_secure_state();
	if (ret != EFI_SUCCESS)
		return ret;

	if (IS_ENABLED(CONFIG_EFI_VARIABLES_PRESEED)) {
		ret = efi_var_restore((struct efi_var_file *)
				      __efi_var_file_begin);
		if (ret != EFI_SUCCESS)
			log_err("Invalid EFI variable seed\n");
	}

	return efi_var_from_file();
}