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 * This code takes all variables accessible from EFI runtime and
9 * exports them via sysfs
10 */
11
12 #include <linux/efi.h>
13 #include <linux/module.h>
14 #include <linux/slab.h>
15 #include <linux/ucs2_string.h>
16 #include <linux/compat.h>
17
18 #define EFIVARS_VERSION "0.08"
19 #define EFIVARS_DATE "2004-May-17"
20
21 MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
22 MODULE_DESCRIPTION("sysfs interface to EFI Variables");
23 MODULE_LICENSE("GPL");
24 MODULE_VERSION(EFIVARS_VERSION);
25
26 static LIST_HEAD(efivar_sysfs_list);
27
28 static struct kset *efivars_kset;
29
30 static struct bin_attribute *efivars_new_var;
31 static struct bin_attribute *efivars_del_var;
32
33 struct compat_efi_variable {
34 efi_char16_t VariableName[EFI_VAR_NAME_LEN/sizeof(efi_char16_t)];
35 efi_guid_t VendorGuid;
36 __u32 DataSize;
37 __u8 Data[1024];
38 __u32 Status;
39 __u32 Attributes;
40 } __packed;
41
42 struct efivar_attribute {
43 struct attribute attr;
44 ssize_t (*show) (struct efivar_entry *entry, char *buf);
45 ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
46 };
47
48 #define EFIVAR_ATTR(_name, _mode, _show, _store) \
49 struct efivar_attribute efivar_attr_##_name = { \
50 .attr = {.name = __stringify(_name), .mode = _mode}, \
51 .show = _show, \
52 .store = _store, \
53 };
54
55 #define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
56 #define to_efivar_entry(obj) container_of(obj, struct efivar_entry, kobj)
57
58 /*
59 * Prototype for sysfs creation function
60 */
61 static int
62 efivar_create_sysfs_entry(struct efivar_entry *new_var);
63
64 static ssize_t
efivar_guid_read(struct efivar_entry * entry,char * buf)65 efivar_guid_read(struct efivar_entry *entry, char *buf)
66 {
67 struct efi_variable *var = &entry->var;
68 char *str = buf;
69
70 if (!entry || !buf)
71 return 0;
72
73 efi_guid_to_str(&var->VendorGuid, str);
74 str += strlen(str);
75 str += sprintf(str, "\n");
76
77 return str - buf;
78 }
79
80 static ssize_t
efivar_attr_read(struct efivar_entry * entry,char * buf)81 efivar_attr_read(struct efivar_entry *entry, char *buf)
82 {
83 struct efi_variable *var = &entry->var;
84 unsigned long size = sizeof(var->Data);
85 char *str = buf;
86 int ret;
87
88 if (!entry || !buf)
89 return -EINVAL;
90
91 ret = efivar_entry_get(entry, &var->Attributes, &size, var->Data);
92 var->DataSize = size;
93 if (ret)
94 return -EIO;
95
96 if (var->Attributes & EFI_VARIABLE_NON_VOLATILE)
97 str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
98 if (var->Attributes & EFI_VARIABLE_BOOTSERVICE_ACCESS)
99 str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
100 if (var->Attributes & EFI_VARIABLE_RUNTIME_ACCESS)
101 str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
102 if (var->Attributes & EFI_VARIABLE_HARDWARE_ERROR_RECORD)
103 str += sprintf(str, "EFI_VARIABLE_HARDWARE_ERROR_RECORD\n");
104 if (var->Attributes & EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS)
105 str += sprintf(str,
106 "EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS\n");
107 if (var->Attributes &
108 EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)
109 str += sprintf(str,
110 "EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS\n");
111 if (var->Attributes & EFI_VARIABLE_APPEND_WRITE)
112 str += sprintf(str, "EFI_VARIABLE_APPEND_WRITE\n");
113 return str - buf;
114 }
115
116 static ssize_t
efivar_size_read(struct efivar_entry * entry,char * buf)117 efivar_size_read(struct efivar_entry *entry, char *buf)
118 {
119 struct efi_variable *var = &entry->var;
120 unsigned long size = sizeof(var->Data);
121 char *str = buf;
122 int ret;
123
124 if (!entry || !buf)
125 return -EINVAL;
126
127 ret = efivar_entry_get(entry, &var->Attributes, &size, var->Data);
128 var->DataSize = size;
129 if (ret)
130 return -EIO;
131
132 str += sprintf(str, "0x%lx\n", var->DataSize);
133 return str - buf;
134 }
135
136 static ssize_t
efivar_data_read(struct efivar_entry * entry,char * buf)137 efivar_data_read(struct efivar_entry *entry, char *buf)
138 {
139 struct efi_variable *var = &entry->var;
140 unsigned long size = sizeof(var->Data);
141 int ret;
142
143 if (!entry || !buf)
144 return -EINVAL;
145
146 ret = efivar_entry_get(entry, &var->Attributes, &size, var->Data);
147 var->DataSize = size;
148 if (ret)
149 return -EIO;
150
151 memcpy(buf, var->Data, var->DataSize);
152 return var->DataSize;
153 }
154
155 static inline int
sanity_check(struct efi_variable * var,efi_char16_t * name,efi_guid_t vendor,unsigned long size,u32 attributes,u8 * data)156 sanity_check(struct efi_variable *var, efi_char16_t *name, efi_guid_t vendor,
157 unsigned long size, u32 attributes, u8 *data)
158 {
159 /*
160 * If only updating the variable data, then the name
161 * and guid should remain the same
162 */
163 if (memcmp(name, var->VariableName, sizeof(var->VariableName)) ||
164 efi_guidcmp(vendor, var->VendorGuid)) {
165 printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
166 return -EINVAL;
167 }
168
169 if ((size <= 0) || (attributes == 0)){
170 printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
171 return -EINVAL;
172 }
173
174 if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
175 efivar_validate(vendor, name, data, size) == false) {
176 printk(KERN_ERR "efivars: Malformed variable content\n");
177 return -EINVAL;
178 }
179
180 return 0;
181 }
182
183 static void
copy_out_compat(struct efi_variable * dst,struct compat_efi_variable * src)184 copy_out_compat(struct efi_variable *dst, struct compat_efi_variable *src)
185 {
186 memcpy(dst->VariableName, src->VariableName, EFI_VAR_NAME_LEN);
187 memcpy(dst->Data, src->Data, sizeof(src->Data));
188
189 dst->VendorGuid = src->VendorGuid;
190 dst->DataSize = src->DataSize;
191 dst->Attributes = src->Attributes;
192 }
193
194 /*
195 * We allow each variable to be edited via rewriting the
196 * entire efi variable structure.
197 */
198 static ssize_t
efivar_store_raw(struct efivar_entry * entry,const char * buf,size_t count)199 efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
200 {
201 struct efi_variable *new_var, *var = &entry->var;
202 efi_char16_t *name;
203 unsigned long size;
204 efi_guid_t vendor;
205 u32 attributes;
206 u8 *data;
207 int err;
208
209 if (!entry || !buf)
210 return -EINVAL;
211
212 if (in_compat_syscall()) {
213 struct compat_efi_variable *compat;
214
215 if (count != sizeof(*compat))
216 return -EINVAL;
217
218 compat = (struct compat_efi_variable *)buf;
219 attributes = compat->Attributes;
220 vendor = compat->VendorGuid;
221 name = compat->VariableName;
222 size = compat->DataSize;
223 data = compat->Data;
224
225 err = sanity_check(var, name, vendor, size, attributes, data);
226 if (err)
227 return err;
228
229 copy_out_compat(&entry->var, compat);
230 } else {
231 if (count != sizeof(struct efi_variable))
232 return -EINVAL;
233
234 new_var = (struct efi_variable *)buf;
235
236 attributes = new_var->Attributes;
237 vendor = new_var->VendorGuid;
238 name = new_var->VariableName;
239 size = new_var->DataSize;
240 data = new_var->Data;
241
242 err = sanity_check(var, name, vendor, size, attributes, data);
243 if (err)
244 return err;
245
246 memcpy(&entry->var, new_var, count);
247 }
248
249 err = efivar_entry_set(entry, attributes, size, data, NULL);
250 if (err) {
251 printk(KERN_WARNING "efivars: set_variable() failed: status=%d\n", err);
252 return -EIO;
253 }
254
255 return count;
256 }
257
258 static ssize_t
efivar_show_raw(struct efivar_entry * entry,char * buf)259 efivar_show_raw(struct efivar_entry *entry, char *buf)
260 {
261 struct efi_variable *var = &entry->var;
262 struct compat_efi_variable *compat;
263 unsigned long datasize = sizeof(var->Data);
264 size_t size;
265 int ret;
266
267 if (!entry || !buf)
268 return 0;
269
270 ret = efivar_entry_get(entry, &var->Attributes, &datasize, var->Data);
271 var->DataSize = datasize;
272 if (ret)
273 return -EIO;
274
275 if (in_compat_syscall()) {
276 compat = (struct compat_efi_variable *)buf;
277
278 size = sizeof(*compat);
279 memcpy(compat->VariableName, var->VariableName,
280 EFI_VAR_NAME_LEN);
281 memcpy(compat->Data, var->Data, sizeof(compat->Data));
282
283 compat->VendorGuid = var->VendorGuid;
284 compat->DataSize = var->DataSize;
285 compat->Attributes = var->Attributes;
286 } else {
287 size = sizeof(*var);
288 memcpy(buf, var, size);
289 }
290
291 return size;
292 }
293
294 /*
295 * Generic read/write functions that call the specific functions of
296 * the attributes...
297 */
efivar_attr_show(struct kobject * kobj,struct attribute * attr,char * buf)298 static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
299 char *buf)
300 {
301 struct efivar_entry *var = to_efivar_entry(kobj);
302 struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
303 ssize_t ret = -EIO;
304
305 if (!capable(CAP_SYS_ADMIN))
306 return -EACCES;
307
308 if (efivar_attr->show) {
309 ret = efivar_attr->show(var, buf);
310 }
311 return ret;
312 }
313
efivar_attr_store(struct kobject * kobj,struct attribute * attr,const char * buf,size_t count)314 static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
315 const char *buf, size_t count)
316 {
317 struct efivar_entry *var = to_efivar_entry(kobj);
318 struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
319 ssize_t ret = -EIO;
320
321 if (!capable(CAP_SYS_ADMIN))
322 return -EACCES;
323
324 if (efivar_attr->store)
325 ret = efivar_attr->store(var, buf, count);
326
327 return ret;
328 }
329
330 static const struct sysfs_ops efivar_attr_ops = {
331 .show = efivar_attr_show,
332 .store = efivar_attr_store,
333 };
334
efivar_release(struct kobject * kobj)335 static void efivar_release(struct kobject *kobj)
336 {
337 struct efivar_entry *var = to_efivar_entry(kobj);
338 kfree(var);
339 }
340
341 static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
342 static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
343 static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
344 static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
345 static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);
346
347 static struct attribute *def_attrs[] = {
348 &efivar_attr_guid.attr,
349 &efivar_attr_size.attr,
350 &efivar_attr_attributes.attr,
351 &efivar_attr_data.attr,
352 &efivar_attr_raw_var.attr,
353 NULL,
354 };
355 ATTRIBUTE_GROUPS(def);
356
357 static struct kobj_type efivar_ktype = {
358 .release = efivar_release,
359 .sysfs_ops = &efivar_attr_ops,
360 .default_groups = def_groups,
361 };
362
efivar_create(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t pos,size_t count)363 static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
364 struct bin_attribute *bin_attr,
365 char *buf, loff_t pos, size_t count)
366 {
367 struct compat_efi_variable *compat = (struct compat_efi_variable *)buf;
368 struct efi_variable *new_var = (struct efi_variable *)buf;
369 struct efivar_entry *new_entry;
370 bool need_compat = in_compat_syscall();
371 efi_char16_t *name;
372 unsigned long size;
373 u32 attributes;
374 u8 *data;
375 int err;
376
377 if (!capable(CAP_SYS_ADMIN))
378 return -EACCES;
379
380 if (need_compat) {
381 if (count != sizeof(*compat))
382 return -EINVAL;
383
384 attributes = compat->Attributes;
385 name = compat->VariableName;
386 size = compat->DataSize;
387 data = compat->Data;
388 } else {
389 if (count != sizeof(*new_var))
390 return -EINVAL;
391
392 attributes = new_var->Attributes;
393 name = new_var->VariableName;
394 size = new_var->DataSize;
395 data = new_var->Data;
396 }
397
398 if ((attributes & ~EFI_VARIABLE_MASK) != 0 ||
399 efivar_validate(new_var->VendorGuid, name, data,
400 size) == false) {
401 printk(KERN_ERR "efivars: Malformed variable content\n");
402 return -EINVAL;
403 }
404
405 new_entry = kzalloc(sizeof(*new_entry), GFP_KERNEL);
406 if (!new_entry)
407 return -ENOMEM;
408
409 if (need_compat)
410 copy_out_compat(&new_entry->var, compat);
411 else
412 memcpy(&new_entry->var, new_var, sizeof(*new_var));
413
414 err = efivar_entry_set(new_entry, attributes, size,
415 data, &efivar_sysfs_list);
416 if (err) {
417 if (err == -EEXIST)
418 err = -EINVAL;
419 goto out;
420 }
421
422 if (efivar_create_sysfs_entry(new_entry)) {
423 printk(KERN_WARNING "efivars: failed to create sysfs entry.\n");
424 kfree(new_entry);
425 }
426 return count;
427
428 out:
429 kfree(new_entry);
430 return err;
431 }
432
efivar_delete(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t pos,size_t count)433 static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
434 struct bin_attribute *bin_attr,
435 char *buf, loff_t pos, size_t count)
436 {
437 struct efi_variable *del_var = (struct efi_variable *)buf;
438 struct compat_efi_variable *compat;
439 struct efivar_entry *entry;
440 efi_char16_t *name;
441 efi_guid_t vendor;
442 int err = 0;
443
444 if (!capable(CAP_SYS_ADMIN))
445 return -EACCES;
446
447 if (in_compat_syscall()) {
448 if (count != sizeof(*compat))
449 return -EINVAL;
450
451 compat = (struct compat_efi_variable *)buf;
452 name = compat->VariableName;
453 vendor = compat->VendorGuid;
454 } else {
455 if (count != sizeof(*del_var))
456 return -EINVAL;
457
458 name = del_var->VariableName;
459 vendor = del_var->VendorGuid;
460 }
461
462 if (efivar_entry_iter_begin())
463 return -EINTR;
464 entry = efivar_entry_find(name, vendor, &efivar_sysfs_list, true);
465 if (!entry)
466 err = -EINVAL;
467 else if (__efivar_entry_delete(entry))
468 err = -EIO;
469
470 if (err) {
471 efivar_entry_iter_end();
472 return err;
473 }
474
475 if (!entry->scanning) {
476 efivar_entry_iter_end();
477 efivar_unregister(entry);
478 } else
479 efivar_entry_iter_end();
480
481 /* It's dead Jim.... */
482 return count;
483 }
484
485 /**
486 * efivar_create_sysfs_entry - create a new entry in sysfs
487 * @new_var: efivar entry to create
488 *
489 * Returns 0 on success, negative error code on failure
490 */
491 static int
efivar_create_sysfs_entry(struct efivar_entry * new_var)492 efivar_create_sysfs_entry(struct efivar_entry *new_var)
493 {
494 int short_name_size;
495 char *short_name;
496 unsigned long utf8_name_size;
497 efi_char16_t *variable_name = new_var->var.VariableName;
498 int ret;
499
500 /*
501 * Length of the variable bytes in UTF8, plus the '-' separator,
502 * plus the GUID, plus trailing NUL
503 */
504 utf8_name_size = ucs2_utf8size(variable_name);
505 short_name_size = utf8_name_size + 1 + EFI_VARIABLE_GUID_LEN + 1;
506
507 short_name = kmalloc(short_name_size, GFP_KERNEL);
508 if (!short_name)
509 return -ENOMEM;
510
511 ucs2_as_utf8(short_name, variable_name, short_name_size);
512
513 /* This is ugly, but necessary to separate one vendor's
514 private variables from another's. */
515 short_name[utf8_name_size] = '-';
516 efi_guid_to_str(&new_var->var.VendorGuid,
517 short_name + utf8_name_size + 1);
518
519 new_var->kobj.kset = efivars_kset;
520
521 ret = kobject_init_and_add(&new_var->kobj, &efivar_ktype,
522 NULL, "%s", short_name);
523 kfree(short_name);
524 if (ret) {
525 kobject_put(&new_var->kobj);
526 return ret;
527 }
528
529 kobject_uevent(&new_var->kobj, KOBJ_ADD);
530 if (efivar_entry_add(new_var, &efivar_sysfs_list)) {
531 efivar_unregister(new_var);
532 return -EINTR;
533 }
534
535 return 0;
536 }
537
538 static int
create_efivars_bin_attributes(void)539 create_efivars_bin_attributes(void)
540 {
541 struct bin_attribute *attr;
542 int error;
543
544 /* new_var */
545 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
546 if (!attr)
547 return -ENOMEM;
548
549 attr->attr.name = "new_var";
550 attr->attr.mode = 0200;
551 attr->write = efivar_create;
552 efivars_new_var = attr;
553
554 /* del_var */
555 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
556 if (!attr) {
557 error = -ENOMEM;
558 goto out_free;
559 }
560 attr->attr.name = "del_var";
561 attr->attr.mode = 0200;
562 attr->write = efivar_delete;
563 efivars_del_var = attr;
564
565 sysfs_bin_attr_init(efivars_new_var);
566 sysfs_bin_attr_init(efivars_del_var);
567
568 /* Register */
569 error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_new_var);
570 if (error) {
571 printk(KERN_ERR "efivars: unable to create new_var sysfs file"
572 " due to error %d\n", error);
573 goto out_free;
574 }
575
576 error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_del_var);
577 if (error) {
578 printk(KERN_ERR "efivars: unable to create del_var sysfs file"
579 " due to error %d\n", error);
580 sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
581 goto out_free;
582 }
583
584 return 0;
585 out_free:
586 kfree(efivars_del_var);
587 efivars_del_var = NULL;
588 kfree(efivars_new_var);
589 efivars_new_var = NULL;
590 return error;
591 }
592
efivars_sysfs_callback(efi_char16_t * name,efi_guid_t vendor,unsigned long name_size,void * data)593 static int efivars_sysfs_callback(efi_char16_t *name, efi_guid_t vendor,
594 unsigned long name_size, void *data)
595 {
596 struct efivar_entry *entry;
597
598 entry = kzalloc(sizeof(*entry), GFP_KERNEL);
599 if (!entry)
600 return -ENOMEM;
601
602 memcpy(entry->var.VariableName, name, name_size);
603 memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
604
605 efivar_create_sysfs_entry(entry);
606
607 return 0;
608 }
609
efivar_sysfs_destroy(struct efivar_entry * entry,void * data)610 static int efivar_sysfs_destroy(struct efivar_entry *entry, void *data)
611 {
612 int err = efivar_entry_remove(entry);
613
614 if (err)
615 return err;
616 efivar_unregister(entry);
617 return 0;
618 }
619
efivars_sysfs_exit(void)620 static void efivars_sysfs_exit(void)
621 {
622 /* Remove all entries and destroy */
623 int err;
624
625 err = __efivar_entry_iter(efivar_sysfs_destroy, &efivar_sysfs_list,
626 NULL, NULL);
627 if (err) {
628 pr_err("efivars: Failed to destroy sysfs entries\n");
629 return;
630 }
631
632 if (efivars_new_var)
633 sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var);
634 if (efivars_del_var)
635 sysfs_remove_bin_file(&efivars_kset->kobj, efivars_del_var);
636 kfree(efivars_new_var);
637 kfree(efivars_del_var);
638 kset_unregister(efivars_kset);
639 }
640
efivars_sysfs_init(void)641 static int efivars_sysfs_init(void)
642 {
643 struct kobject *parent_kobj = efivars_kobject();
644 int error = 0;
645
646 /* No efivars has been registered yet */
647 if (!parent_kobj || !efivar_supports_writes())
648 return 0;
649
650 printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
651 EFIVARS_DATE);
652
653 efivars_kset = kset_create_and_add("vars", NULL, parent_kobj);
654 if (!efivars_kset) {
655 printk(KERN_ERR "efivars: Subsystem registration failed.\n");
656 return -ENOMEM;
657 }
658
659 efivar_init(efivars_sysfs_callback, NULL, true, &efivar_sysfs_list);
660
661 error = create_efivars_bin_attributes();
662 if (error) {
663 efivars_sysfs_exit();
664 return error;
665 }
666
667 return 0;
668 }
669
670 module_init(efivars_sysfs_init);
671 module_exit(efivars_sysfs_exit);
672