summaryrefslogtreecommitdiff
path: root/lib/efi_loader/efi_variable.c
blob: 8a0e0db13e7f39c931d87e03a750a41792ec09ee (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
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
// SPDX-License-Identifier: GPL-2.0+
/*
 *  EFI utils
 *
 *  Copyright (c) 2017 Rob Clark
 */

#include <env.h>
#include <malloc.h>
#include <charset.h>
#include <efi_loader.h>
#include <hexdump.h>
#include <environment.h>
#include <search.h>
#include <uuid.h>

#define READ_ONLY BIT(31)

/*
 * Mapping between EFI variables and u-boot variables:
 *
 *   efi_$guid_$varname = {attributes}(type)value
 *
 * For example:
 *
 *   efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_OsIndicationsSupported=
 *      "{ro,boot,run}(blob)0000000000000000"
 *   efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_BootOrder=
 *      "(blob)00010000"
 *
 * The attributes are a comma separated list of these possible
 * attributes:
 *
 *   + ro   - read-only
 *   + boot - boot-services access
 *   + run  - runtime access
 *
 * NOTE: with current implementation, no variables are available after
 * ExitBootServices, and all are persisted (if possible).
 *
 * If not specified, the attributes default to "{boot}".
 *
 * The required type is one of:
 *
 *   + utf8 - raw utf8 string
 *   + blob - arbitrary length hex string
 *
 * Maybe a utf16 type would be useful to for a string value to be auto
 * converted to utf16?
 */

#define PREFIX_LEN (strlen("efi_xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx_"))

/**
 * efi_to_native() - convert the UEFI variable name and vendor GUID to U-Boot
 *		     variable name
 *
 * The U-Boot variable name is a concatenation of prefix 'efi', the hexstring
 * encoded vendor GUID, and the UTF-8 encoded UEFI variable name separated by
 * underscores, e.g. 'efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_BootOrder'.
 *
 * @native:		pointer to pointer to U-Boot variable name
 * @variable_name:	UEFI variable name
 * @vendor:		vendor GUID
 * Return:		status code
 */
static efi_status_t efi_to_native(char **native, const u16 *variable_name,
				  const efi_guid_t *vendor)
{
	size_t len;
	char *pos;

	len = PREFIX_LEN + utf16_utf8_strlen(variable_name) + 1;
	*native = malloc(len);
	if (!*native)
		return EFI_OUT_OF_RESOURCES;

	pos = *native;
	pos += sprintf(pos, "efi_%pUl_", vendor);
	utf16_utf8_strcpy(&pos, variable_name);

	return EFI_SUCCESS;
}

/**
 * prefix() - skip over prefix
 *
 * Skip over a prefix string.
 *
 * @str:	string with prefix
 * @prefix:	prefix string
 * Return:	string without prefix, or NULL if prefix not found
 */
static const char *prefix(const char *str, const char *prefix)
{
	size_t n = strlen(prefix);
	if (!strncmp(prefix, str, n))
		return str + n;
	return NULL;
}

/**
 * parse_attr() - decode attributes part of variable value
 *
 * Convert the string encoded attributes of a UEFI variable to a bit mask.
 * TODO: Several attributes are not supported.
 *
 * @str:	value of U-Boot variable
 * @attrp:	pointer to UEFI attributes
 * Return:	pointer to remainder of U-Boot variable value
 */
static const char *parse_attr(const char *str, u32 *attrp)
{
	u32 attr = 0;
	char sep = '{';

	if (*str != '{') {
		*attrp = EFI_VARIABLE_BOOTSERVICE_ACCESS;
		return str;
	}

	while (*str == sep) {
		const char *s;

		str++;

		if ((s = prefix(str, "ro"))) {
			attr |= READ_ONLY;
		} else if ((s = prefix(str, "nv"))) {
			attr |= EFI_VARIABLE_NON_VOLATILE;
		} else if ((s = prefix(str, "boot"))) {
			attr |= EFI_VARIABLE_BOOTSERVICE_ACCESS;
		} else if ((s = prefix(str, "run"))) {
			attr |= EFI_VARIABLE_RUNTIME_ACCESS;
		} else {
			printf("invalid attribute: %s\n", str);
			break;
		}

		str = s;
		sep = ',';
	}

	str++;

	*attrp = attr;

	return str;
}

/**
 * efi_get_variable() - retrieve value of a UEFI variable
 *
 * This function implements the GetVariable runtime service.
 *
 * See the Unified Extensible Firmware Interface (UEFI) specification for
 * details.
 *
 * @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
 */
efi_status_t EFIAPI efi_get_variable(u16 *variable_name,
				     const efi_guid_t *vendor, u32 *attributes,
				     efi_uintn_t *data_size, void *data)
{
	char *native_name;
	efi_status_t ret;
	unsigned long in_size;
	const char *val, *s;
	u32 attr;

	EFI_ENTRY("\"%ls\" %pUl %p %p %p", variable_name, vendor, attributes,
		  data_size, data);

	if (!variable_name || !vendor || !data_size)
		return EFI_EXIT(EFI_INVALID_PARAMETER);

	ret = efi_to_native(&native_name, variable_name, vendor);
	if (ret)
		return EFI_EXIT(ret);

	EFI_PRINT("get '%s'\n", native_name);

	val = env_get(native_name);
	free(native_name);
	if (!val)
		return EFI_EXIT(EFI_NOT_FOUND);

	val = parse_attr(val, &attr);

	in_size = *data_size;

	if ((s = prefix(val, "(blob)"))) {
		size_t len = strlen(s);

		/* number of hexadecimal digits must be even */
		if (len & 1)
			return EFI_EXIT(EFI_DEVICE_ERROR);

		/* two characters per byte: */
		len /= 2;
		*data_size = len;

		if (in_size < len) {
			ret = EFI_BUFFER_TOO_SMALL;
			goto out;
		}

		if (!data)
			return EFI_EXIT(EFI_INVALID_PARAMETER);

		if (hex2bin(data, s, len))
			return EFI_EXIT(EFI_DEVICE_ERROR);

		EFI_PRINT("got value: \"%s\"\n", s);
	} else if ((s = prefix(val, "(utf8)"))) {
		unsigned len = strlen(s) + 1;

		*data_size = len;

		if (in_size < len) {
			ret = EFI_BUFFER_TOO_SMALL;
			goto out;
		}

		if (!data)
			return EFI_EXIT(EFI_INVALID_PARAMETER);

		memcpy(data, s, len);
		((char *)data)[len] = '\0';

		EFI_PRINT("got value: \"%s\"\n", (char *)data);
	} else {
		EFI_PRINT("invalid value: '%s'\n", val);
		return EFI_EXIT(EFI_DEVICE_ERROR);
	}

out:
	if (attributes)
		*attributes = attr & EFI_VARIABLE_MASK;

	return EFI_EXIT(ret);
}

static char *efi_variables_list;
static char *efi_cur_variable;

/**
 * parse_uboot_variable() - parse a u-boot variable and get uefi-related
 *			    information
 * @variable:		whole data of u-boot variable (ie. name=value)
 * @variable_name_size: size of variable_name buffer in byte
 * @variable_name:	name of uefi variable in u16, null-terminated
 * @vendor:		vendor's guid
 * @attributes:		attributes
 *
 * A uefi variable is encoded into a u-boot variable as described above.
 * This function parses such a u-boot variable and retrieve uefi-related
 * information into respective parameters. In return, variable_name_size
 * is the size of variable name including NULL.
 *
 * Return:		EFI_SUCCESS if parsing is OK, EFI_NOT_FOUND when
 *			the entire variable list has been returned,
 *			otherwise non-zero status code
 */
static efi_status_t parse_uboot_variable(char *variable,
					 efi_uintn_t *variable_name_size,
					 u16 *variable_name,
					 const efi_guid_t *vendor,
					 u32 *attributes)
{
	char *guid, *name, *end, c;
	unsigned long name_len;
	u16 *p;

	guid = strchr(variable, '_');
	if (!guid)
		return EFI_INVALID_PARAMETER;
	guid++;
	name = strchr(guid, '_');
	if (!name)
		return EFI_INVALID_PARAMETER;
	name++;
	end = strchr(name, '=');
	if (!end)
		return EFI_INVALID_PARAMETER;

	name_len = end - name;
	if (*variable_name_size < (name_len + 1)) {
		*variable_name_size = name_len + 1;
		return EFI_BUFFER_TOO_SMALL;
	}
	end++; /* point to value */

	/* variable name */
	p = variable_name;
	utf8_utf16_strncpy(&p, name, name_len);
	variable_name[name_len] = 0;
	*variable_name_size = name_len + 1;

	/* guid */
	c = *(name - 1);
	*(name - 1) = '\0'; /* guid need be null-terminated here */
	uuid_str_to_bin(guid, (unsigned char *)vendor, UUID_STR_FORMAT_GUID);
	*(name - 1) = c;

	/* attributes */
	parse_attr(end, attributes);

	return EFI_SUCCESS;
}

/**
 * efi_get_next_variable_name() - enumerate the current variable names
 *
 * @variable_name_size:	size of variable_name buffer in byte
 * @variable_name:	name of uefi variable's name in u16
 * @vendor:		vendor's guid
 *
 * This function implements the GetNextVariableName service.
 *
 * See the Unified Extensible Firmware Interface (UEFI) specification for
 * details.
 *
 * Return: status code
 */
efi_status_t EFIAPI efi_get_next_variable_name(efi_uintn_t *variable_name_size,
					       u16 *variable_name,
					       const efi_guid_t *vendor)
{
	char *native_name, *variable;
	ssize_t name_len, list_len;
	char regex[256];
	char * const regexlist[] = {regex};
	u32 attributes;
	int i;
	efi_status_t ret;

	EFI_ENTRY("%p \"%ls\" %pUl", variable_name_size, variable_name, vendor);

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

	if (variable_name[0]) {
		/* check null-terminated string */
		for (i = 0; i < *variable_name_size; i++)
			if (!variable_name[i])
				break;
		if (i >= *variable_name_size)
			return EFI_EXIT(EFI_INVALID_PARAMETER);

		/* search for the last-returned variable */
		ret = efi_to_native(&native_name, variable_name, vendor);
		if (ret)
			return EFI_EXIT(ret);

		name_len = strlen(native_name);
		for (variable = efi_variables_list; variable && *variable;) {
			if (!strncmp(variable, native_name, name_len) &&
			    variable[name_len] == '=')
				break;

			variable = strchr(variable, '\n');
			if (variable)
				variable++;
		}

		free(native_name);
		if (!(variable && *variable))
			return EFI_EXIT(EFI_INVALID_PARAMETER);

		/* next variable */
		variable = strchr(variable, '\n');
		if (variable)
			variable++;
		if (!(variable && *variable))
			return EFI_EXIT(EFI_NOT_FOUND);
	} else {
		/*
		 *new search: free a list used in the previous search
		 */
		free(efi_variables_list);
		efi_variables_list = NULL;
		efi_cur_variable = NULL;

		snprintf(regex, 256, "efi_.*-.*-.*-.*-.*_.*");
		list_len = hexport_r(&env_htab, '\n',
				     H_MATCH_REGEX | H_MATCH_KEY,
				     &efi_variables_list, 0, 1, regexlist);
		/* 1 indicates that no match was found */
		if (list_len <= 1)
			return EFI_EXIT(EFI_NOT_FOUND);

		variable = efi_variables_list;
	}

	ret = parse_uboot_variable(variable, variable_name_size, variable_name,
				   vendor, &attributes);

	return EFI_EXIT(ret);
}

/**
 * efi_set_variable() - set value of a UEFI variable
 *
 * This function implements the SetVariable runtime service.
 *
 * See the Unified Extensible Firmware Interface (UEFI) specification for
 * details.
 *
 * @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
 */
efi_status_t EFIAPI efi_set_variable(u16 *variable_name,
				     const efi_guid_t *vendor, u32 attributes,
				     efi_uintn_t data_size, const void *data)
{
	char *native_name = NULL, *val = NULL, *s;
	efi_status_t ret = EFI_SUCCESS;
	u32 attr;

	EFI_ENTRY("\"%ls\" %pUl %x %zu %p", variable_name, vendor, attributes,
		  data_size, data);

	/* TODO: implement APPEND_WRITE */
	if (!variable_name || !*variable_name || !vendor ||
	    ((attributes & EFI_VARIABLE_RUNTIME_ACCESS) &&
	     !(attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)) ||
	    (attributes & EFI_VARIABLE_APPEND_WRITE)) {
		ret = EFI_INVALID_PARAMETER;
		goto out;
	}

	ret = efi_to_native(&native_name, variable_name, vendor);
	if (ret)
		goto out;

#define ACCESS_ATTR (EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_BOOTSERVICE_ACCESS)

	if ((data_size == 0) || !(attributes & ACCESS_ATTR)) {
		/* delete the variable: */
		env_set(native_name, NULL);
		ret = EFI_SUCCESS;
		goto out;
	}

	val = env_get(native_name);
	if (val) {
		parse_attr(val, &attr);

		/* We should not free val */
		val = NULL;
		if (attr & READ_ONLY) {
			ret = EFI_WRITE_PROTECTED;
			goto out;
		}

		/*
		 * attributes won't be changed
		 * TODO: take care of APPEND_WRITE once supported
		 */
		if (attr != attributes) {
			ret = EFI_INVALID_PARAMETER;
			goto out;
		}
	}

	val = malloc(2 * data_size + strlen("{ro,run,boot,nv}(blob)") + 1);
	if (!val) {
		ret = EFI_OUT_OF_RESOURCES;
		goto out;
	}

	s = val;

	/*
	 * store attributes
	 * TODO: several attributes are not supported
	 */
	attributes &= (EFI_VARIABLE_NON_VOLATILE |
		       EFI_VARIABLE_BOOTSERVICE_ACCESS |
		       EFI_VARIABLE_RUNTIME_ACCESS);
	s += sprintf(s, "{");
	while (attributes) {
		u32 attr = 1 << (ffs(attributes) - 1);

		if (attr == EFI_VARIABLE_NON_VOLATILE)
			s += sprintf(s, "nv");
		else if (attr == EFI_VARIABLE_BOOTSERVICE_ACCESS)
			s += sprintf(s, "boot");
		else if (attr == EFI_VARIABLE_RUNTIME_ACCESS)
			s += sprintf(s, "run");

		attributes &= ~attr;
		if (attributes)
			s += sprintf(s, ",");
	}
	s += sprintf(s, "}");

	/* store payload: */
	s += sprintf(s, "(blob)");
	s = bin2hex(s, data, data_size);
	*s = '\0';

	EFI_PRINT("setting: %s=%s\n", native_name, val);

	if (env_set(native_name, val))
		ret = EFI_DEVICE_ERROR;

out:
	free(native_name);
	free(val);

	return EFI_EXIT(ret);
}

/**
 * efi_query_variable_info() - get information about EFI variables
 *
 * This function implements the QueryVariableInfo() runtime service.
 *
 * See the Unified Extensible Firmware Interface (UEFI) specification for
 * details.
 *
 * @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(
			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)
{
	return EFI_UNSUPPORTED;
}

/**
 * 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, const efi_guid_t *vendor)
{
	return EFI_UNSUPPORTED;
}

/**
 * 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)
{
	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_update_table_header_crc32(&efi_runtime_services.hdr);
}

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