summaryrefslogtreecommitdiff
path: root/drivers/firmware/efi/efivars.c
blob: 7576450c8254b8cc8c1cada05a1c9ac61922ea1f (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
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
// SPDX-License-Identifier: GPL-2.0+
/*
 * Originally from efivars.c,
 *
 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
 *
 * This code takes all variables accessible from EFI runtime and
 *  exports them via sysfs
 */

#include <linux/efi.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/ucs2_string.h>
#include <linux/compat.h>

#define EFIVARS_VERSION "0.08"
#define EFIVARS_DATE "2004-May-17"

MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
MODULE_DESCRIPTION("sysfs interface to EFI Variables");
MODULE_LICENSE("GPL");
MODULE_VERSION(EFIVARS_VERSION);
MODULE_ALIAS("platform:efivars");

LIST_HEAD(efivar_sysfs_list);
EXPORT_SYMBOL_GPL(efivar_sysfs_list);

static struct kset *efivars_kset;

static struct bin_attribute *efivars_new_var;
static struct bin_attribute *efivars_del_var;

struct compat_efi_variable {
	efi_char16_t  VariableName[EFI_VAR_NAME_LEN/sizeof(efi_char16_t)];
	efi_guid_t    VendorGuid;
	__u32         DataSize;
	__u8          Data[1024];
	__u32         Status;
	__u32         Attributes;
} __packed;

struct efivar_attribute {
	struct attribute attr;
	ssize_t (*show) (struct efivar_entry *entry, char *buf);
	ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
};

#define EFIVAR_ATTR(_name, _mode, _show, _store) \
struct efivar_attribute efivar_attr_##_name = { \
	.attr = {.name = __stringify(_name), .mode = _mode}, \
	.show = _show, \
	.store = _store, \
};

#define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
#define to_efivar_entry(obj)  container_of(obj, struct efivar_entry, kobj)

/*
 * Prototype for sysfs creation function
 */
static int
efivar_create_sysfs_entry(struct efivar_entry *new_var);

static ssize_t
efivar_guid_read(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	char *str = buf;

	if (!entry || !buf)
		return 0;

	efi_guid_to_str(&var->VendorGuid, str);
	str += strlen(str);
	str += sprintf(str, "\n");

	return str - buf;
}

static ssize_t
efivar_attr_read(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	char *str = buf;

	if (!entry || !buf)
		return -EINVAL;

	var->DataSize = 1024;
	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
		return -EIO;

	if (var->Attributes & EFI_VARIABLE_NON_VOLATILE)
		str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
	if (var->Attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)
		str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
	if (var->Attributes & EFI_VARIABLE_RUNTIME_ACCESS)
		str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
	if (var->Attributes & EFI_VARIABLE_HARDWARE_ERROR_RECORD)
		str += sprintf(str, "EFI_VARIABLE_HARDWARE_ERROR_RECORD\n");
	if (var->Attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS)
		str += sprintf(str,
			"EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS\n");
	if (var->Attributes &
			EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)
		str += sprintf(str,
			"EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS\n");
	if (var->Attributes & EFI_VARIABLE_APPEND_WRITE)
		str += sprintf(str, "EFI_VARIABLE_APPEND_WRITE\n");
	return str - buf;
}

static ssize_t
efivar_size_read(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	char *str = buf;

	if (!entry || !buf)
		return -EINVAL;

	var->DataSize = 1024;
	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
		return -EIO;

	str += sprintf(str, "0x%lx\n", var->DataSize);
	return str - buf;
}

static ssize_t
efivar_data_read(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;

	if (!entry || !buf)
		return -EINVAL;

	var->DataSize = 1024;
	if (efivar_entry_get(entry, &var->Attributes, &var->DataSize, var->Data))
		return -EIO;

	memcpy(buf, var->Data, var->DataSize);
	return var->DataSize;
}

static inline int
sanity_check(struct efi_variable *var, efi_char16_t *name, efi_guid_t vendor,
	     unsigned long size, u32 attributes, u8 *data)
{
	/*
	 * If only updating the variable data, then the name
	 * and guid should remain the same
	 */
	if (memcmp(name, var->VariableName, sizeof(var->VariableName)) ||
		efi_guidcmp(vendor, var->VendorGuid)) {
		printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
		return -EINVAL;
	}

	if ((size <= 0) || (attributes == 0)){
		printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
		return -EINVAL;
	}

	if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
	    efivar_validate(vendor, name, data, size) == false) {
		printk(KERN_ERR "efivars: Malformed variable content\n");
		return -EINVAL;
	}

	return 0;
}

static void
copy_out_compat(struct efi_variable *dst, struct compat_efi_variable *src)
{
	memcpy(dst->VariableName, src->VariableName, EFI_VAR_NAME_LEN);
	memcpy(dst->Data, src->Data, sizeof(src->Data));

	dst->VendorGuid = src->VendorGuid;
	dst->DataSize = src->DataSize;
	dst->Attributes = src->Attributes;
}

/*
 * We allow each variable to be edited via rewriting the
 * entire efi variable structure.
 */
static ssize_t
efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
{
	struct efi_variable *new_var, *var = &entry->var;
	efi_char16_t *name;
	unsigned long size;
	efi_guid_t vendor;
	u32 attributes;
	u8 *data;
	int err;

	if (in_compat_syscall()) {
		struct compat_efi_variable *compat;

		if (count != sizeof(*compat))
			return -EINVAL;

		compat = (struct compat_efi_variable *)buf;
		attributes = compat->Attributes;
		vendor = compat->VendorGuid;
		name = compat->VariableName;
		size = compat->DataSize;
		data = compat->Data;

		err = sanity_check(var, name, vendor, size, attributes, data);
		if (err)
			return err;

		copy_out_compat(&entry->var, compat);
	} else {
		if (count != sizeof(struct efi_variable))
			return -EINVAL;

		new_var = (struct efi_variable *)buf;

		attributes = new_var->Attributes;
		vendor = new_var->VendorGuid;
		name = new_var->VariableName;
		size = new_var->DataSize;
		data = new_var->Data;

		err = sanity_check(var, name, vendor, size, attributes, data);
		if (err)
			return err;

		memcpy(&entry->var, new_var, count);
	}

	err = efivar_entry_set(entry, attributes, size, data, NULL);
	if (err) {
		printk(KERN_WARNING "efivars: set_variable() failed: status=%d\n", err);
		return -EIO;
	}

	return count;
}

static ssize_t
efivar_show_raw(struct efivar_entry *entry, char *buf)
{
	struct efi_variable *var = &entry->var;
	struct compat_efi_variable *compat;
	size_t size;

	if (!entry || !buf)
		return 0;

	var->DataSize = 1024;
	if (efivar_entry_get(entry, &entry->var.Attributes,
			     &entry->var.DataSize, entry->var.Data))
		return -EIO;

	if (in_compat_syscall()) {
		compat = (struct compat_efi_variable *)buf;

		size = sizeof(*compat);
		memcpy(compat->VariableName, var->VariableName,
			EFI_VAR_NAME_LEN);
		memcpy(compat->Data, var->Data, sizeof(compat->Data));

		compat->VendorGuid = var->VendorGuid;
		compat->DataSize = var->DataSize;
		compat->Attributes = var->Attributes;
	} else {
		size = sizeof(*var);
		memcpy(buf, var, size);
	}

	return size;
}

/*
 * Generic read/write functions that call the specific functions of
 * the attributes...
 */
static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
				char *buf)
{
	struct efivar_entry *var = to_efivar_entry(kobj);
	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
	ssize_t ret = -EIO;

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (efivar_attr->show) {
		ret = efivar_attr->show(var, buf);
	}
	return ret;
}

static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
				const char *buf, size_t count)
{
	struct efivar_entry *var = to_efivar_entry(kobj);
	struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
	ssize_t ret = -EIO;

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (efivar_attr->store)
		ret = efivar_attr->store(var, buf, count);

	return ret;
}

static const struct sysfs_ops efivar_attr_ops = {
	.show = efivar_attr_show,
	.store = efivar_attr_store,
};

static void efivar_release(struct kobject *kobj)
{
	struct efivar_entry *var = to_efivar_entry(kobj);
	kfree(var);
}

static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);

static struct attribute *def_attrs[] = {
	&efivar_attr_guid.attr,
	&efivar_attr_size.attr,
	&efivar_attr_attributes.attr,
	&efivar_attr_data.attr,
	&efivar_attr_raw_var.attr,
	NULL,
};

static struct kobj_type efivar_ktype = {
	.release = efivar_release,
	.sysfs_ops = &efivar_attr_ops,
	.default_attrs = def_attrs,
};

static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
			     struct bin_attribute *bin_attr,
			     char *buf, loff_t pos, size_t count)
{
	struct compat_efi_variable *compat = (struct compat_efi_variable *)buf;
	struct efi_variable *new_var = (struct efi_variable *)buf;
	struct efivar_entry *new_entry;
	bool need_compat = in_compat_syscall();
	efi_char16_t *name;
	unsigned long size;
	u32 attributes;
	u8 *data;
	int err;

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (need_compat) {
		if (count != sizeof(*compat))
			return -EINVAL;

		attributes = compat->Attributes;
		name = compat->VariableName;
		size = compat->DataSize;
		data = compat->Data;
	} else {
		if (count != sizeof(*new_var))
			return -EINVAL;

		attributes = new_var->Attributes;
		name = new_var->VariableName;
		size = new_var->DataSize;
		data = new_var->Data;
	}

	if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
	    efivar_validate(new_var->VendorGuid, name, data,
			    size) == false) {
		printk(KERN_ERR "efivars: Malformed variable content\n");
		return -EINVAL;
	}

	new_entry = kzalloc(sizeof(*new_entry), GFP_KERNEL);
	if (!new_entry)
		return -ENOMEM;

	if (need_compat)
		copy_out_compat(&new_entry->var, compat);
	else
		memcpy(&new_entry->var, new_var, sizeof(*new_var));

	err = efivar_entry_set(new_entry, attributes, size,
			       data, &efivar_sysfs_list);
	if (err) {
		if (err == -EEXIST)
			err = -EINVAL;
		goto out;
	}

	if (efivar_create_sysfs_entry(new_entry)) {
		printk(KERN_WARNING "efivars: failed to create sysfs entry.\n");
		kfree(new_entry);
	}
	return count;

out:
	kfree(new_entry);
	return err;
}

static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
			     struct bin_attribute *bin_attr,
			     char *buf, loff_t pos, size_t count)
{
	struct efi_variable *del_var = (struct efi_variable *)buf;
	struct compat_efi_variable *compat;
	struct efivar_entry *entry;
	efi_char16_t *name;
	efi_guid_t vendor;
	int err = 0;

	if (!capable(CAP_SYS_ADMIN))
		return -EACCES;

	if (in_compat_syscall()) {
		if (count != sizeof(*compat))
			return -EINVAL;

		compat = (struct compat_efi_variable *)buf;
		name = compat->VariableName;
		vendor = compat->VendorGuid;
	} else {
		if (count != sizeof(*del_var))
			return -EINVAL;

		name = del_var->VariableName;
		vendor = del_var->VendorGuid;
	}

	if (efivar_entry_iter_begin())
		return -EINTR;
	entry = efivar_entry_find(name, vendor, &efivar_sysfs_list, true);
	if (!entry)
		err = -EINVAL;
	else if (__efivar_entry_delete(entry))
		err = -EIO;

	if (err) {
		efivar_entry_iter_end();
		return err;
	}

	if (!entry->scanning) {
		efivar_entry_iter_end();
		efivar_unregister(entry);
	} else
		efivar_entry_iter_end();

	/* It's dead Jim.... */
	return count;
}

/**
 * efivar_create_sysfs_entry - create a new entry in sysfs
 * @new_var: efivar entry to create
 *
 * Returns 0 on success, negative error code on failure
 */
static int
efivar_create_sysfs_entry(struct efivar_entry *new_var)
{
	int short_name_size;
	char *short_name;
	unsigned long utf8_name_size;
	efi_char16_t *variable_name = new_var->var.VariableName;
	int ret;

	/*
	 * Length of the variable bytes in UTF8, plus the '-' separator,
	 * plus the GUID, plus trailing NUL
	 */
	utf8_name_size = ucs2_utf8size(variable_name);
	short_name_size = utf8_name_size + 1 + EFI_VARIABLE_GUID_LEN + 1;

	short_name = kmalloc(short_name_size, GFP_KERNEL);
	if (!short_name)
		return -ENOMEM;

	ucs2_as_utf8(short_name, variable_name, short_name_size);

	/* This is ugly, but necessary to separate one vendor's
	   private variables from another's.         */
	short_name[utf8_name_size] = '-';
	efi_guid_to_str(&new_var->var.VendorGuid,
			 short_name + utf8_name_size + 1);

	new_var->kobj.kset = efivars_kset;

	ret = kobject_init_and_add(&new_var->kobj, &efivar_ktype,
				   NULL, "%s", short_name);
	kfree(short_name);
	if (ret)
		return ret;

	kobject_uevent(&new_var->kobj, KOBJ_ADD);
	if (efivar_entry_add(new_var, &efivar_sysfs_list)) {
		efivar_unregister(new_var);
		return -EINTR;
	}

	return 0;
}

static int
create_efivars_bin_attributes(void)
{
	struct bin_attribute *attr;
	int error;

	/* new_var */
	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
	if (!attr)
		return -ENOMEM;

	attr->attr.name = "new_var";
	attr->attr.mode = 0200;
	attr->write = efivar_create;
	efivars_new_var = attr;

	/* del_var */
	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
	if (!attr) {
		error = -ENOMEM;
		goto out_free;
	}
	attr->attr.name = "del_var";
	attr->attr.mode = 0200;
	attr->write = efivar_delete;
	efivars_del_var = attr;

	sysfs_bin_attr_init(efivars_new_var);
	sysfs_bin_attr_init(efivars_del_var);

	/* Register */
	error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_new_var);
	if (error) {
		printk(KERN_ERR "efivars: unable to create new_var sysfs file"
			" due to error %d\n", error);
		goto out_free;
	}

	error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_del_var);
	if (error) {
		printk(KERN_ERR "efivars: unable to create del_var sysfs file"
			" due to error %d\n", error);
		sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
		goto out_free;
	}

	return 0;
out_free:
	kfree(efivars_del_var);
	efivars_del_var = NULL;
	kfree(efivars_new_var);
	efivars_new_var = NULL;
	return error;
}

static int efivar_update_sysfs_entry(efi_char16_t *name, efi_guid_t vendor,
				     unsigned long name_size, void *data)
{
	struct efivar_entry *entry = data;

	if (efivar_entry_find(name, vendor, &efivar_sysfs_list, false))
		return 0;

	memcpy(entry->var.VariableName, name, name_size);
	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));

	return 1;
}

static void efivar_update_sysfs_entries(struct work_struct *work)
{
	struct efivar_entry *entry;
	int err;

	/* Add new sysfs entries */
	while (1) {
		entry = kzalloc(sizeof(*entry), GFP_KERNEL);
		if (!entry)
			return;

		err = efivar_init(efivar_update_sysfs_entry, entry,
				  false, &efivar_sysfs_list);
		if (!err)
			break;

		efivar_create_sysfs_entry(entry);
	}

	kfree(entry);
}

static int efivars_sysfs_callback(efi_char16_t *name, efi_guid_t vendor,
				  unsigned long name_size, void *data)
{
	struct efivar_entry *entry;

	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	if (!entry)
		return -ENOMEM;

	memcpy(entry->var.VariableName, name, name_size);
	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));

	efivar_create_sysfs_entry(entry);

	return 0;
}

static int efivar_sysfs_destroy(struct efivar_entry *entry, void *data)
{
	int err = efivar_entry_remove(entry);

	if (err)
		return err;
	efivar_unregister(entry);
	return 0;
}

static void efivars_sysfs_exit(void)
{
	/* Remove all entries and destroy */
	int err;

	err = __efivar_entry_iter(efivar_sysfs_destroy, &efivar_sysfs_list,
				  NULL, NULL);
	if (err) {
		pr_err("efivars: Failed to destroy sysfs entries\n");
		return;
	}

	if (efivars_new_var)
		sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
	if (efivars_del_var)
		sysfs_remove_bin_file(&efivars_kset->kobj, efivars_del_var);
	kfree(efivars_new_var);
	kfree(efivars_del_var);
	kset_unregister(efivars_kset);
}

int efivars_sysfs_init(void)
{
	struct kobject *parent_kobj = efivars_kobject();
	int error = 0;

	if (!efi_enabled(EFI_RUNTIME_SERVICES))
		return -ENODEV;

	/* No efivars has been registered yet */
	if (!parent_kobj)
		return 0;

	printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
	       EFIVARS_DATE);

	efivars_kset = kset_create_and_add("vars", NULL, parent_kobj);
	if (!efivars_kset) {
		printk(KERN_ERR "efivars: Subsystem registration failed.\n");
		return -ENOMEM;
	}

	efivar_init(efivars_sysfs_callback, NULL, true, &efivar_sysfs_list);

	error = create_efivars_bin_attributes();
	if (error) {
		efivars_sysfs_exit();
		return error;
	}

	INIT_WORK(&efivar_work, efivar_update_sysfs_entries);

	return 0;
}
EXPORT_SYMBOL_GPL(efivars_sysfs_init);

module_init(efivars_sysfs_init);
module_exit(efivars_sysfs_exit);