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 }; 355 356 static struct kobj_type efivar_ktype = { 357 .release = efivar_release, 358 .sysfs_ops = &efivar_attr_ops, 359 .default_attrs = def_attrs, 360 }; 361 efivar_create(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t pos,size_t count)362 static ssize_t efivar_create(struct file *filp, struct kobject *kobj, 363 struct bin_attribute *bin_attr, 364 char *buf, loff_t pos, size_t count) 365 { 366 struct compat_efi_variable *compat = (struct compat_efi_variable *)buf; 367 struct efi_variable *new_var = (struct efi_variable *)buf; 368 struct efivar_entry *new_entry; 369 bool need_compat = in_compat_syscall(); 370 efi_char16_t *name; 371 unsigned long size; 372 u32 attributes; 373 u8 *data; 374 int err; 375 376 if (!capable(CAP_SYS_ADMIN)) 377 return -EACCES; 378 379 if (need_compat) { 380 if (count != sizeof(*compat)) 381 return -EINVAL; 382 383 attributes = compat->Attributes; 384 name = compat->VariableName; 385 size = compat->DataSize; 386 data = compat->Data; 387 } else { 388 if (count != sizeof(*new_var)) 389 return -EINVAL; 390 391 attributes = new_var->Attributes; 392 name = new_var->VariableName; 393 size = new_var->DataSize; 394 data = new_var->Data; 395 } 396 397 if ((attributes & ~EFI_VARIABLE_MASK) != 0 || 398 efivar_validate(new_var->VendorGuid, name, data, 399 size) == false) { 400 printk(KERN_ERR "efivars: Malformed variable content\n"); 401 return -EINVAL; 402 } 403 404 new_entry = kzalloc(sizeof(*new_entry), GFP_KERNEL); 405 if (!new_entry) 406 return -ENOMEM; 407 408 if (need_compat) 409 copy_out_compat(&new_entry->var, compat); 410 else 411 memcpy(&new_entry->var, new_var, sizeof(*new_var)); 412 413 err = efivar_entry_set(new_entry, attributes, size, 414 data, &efivar_sysfs_list); 415 if (err) { 416 if (err == -EEXIST) 417 err = -EINVAL; 418 goto out; 419 } 420 421 if (efivar_create_sysfs_entry(new_entry)) { 422 printk(KERN_WARNING "efivars: failed to create sysfs entry.\n"); 423 kfree(new_entry); 424 } 425 return count; 426 427 out: 428 kfree(new_entry); 429 return err; 430 } 431 efivar_delete(struct file * filp,struct kobject * kobj,struct bin_attribute * bin_attr,char * buf,loff_t pos,size_t count)432 static ssize_t efivar_delete(struct file *filp, struct kobject *kobj, 433 struct bin_attribute *bin_attr, 434 char *buf, loff_t pos, size_t count) 435 { 436 struct efi_variable *del_var = (struct efi_variable *)buf; 437 struct compat_efi_variable *compat; 438 struct efivar_entry *entry; 439 efi_char16_t *name; 440 efi_guid_t vendor; 441 int err = 0; 442 443 if (!capable(CAP_SYS_ADMIN)) 444 return -EACCES; 445 446 if (in_compat_syscall()) { 447 if (count != sizeof(*compat)) 448 return -EINVAL; 449 450 compat = (struct compat_efi_variable *)buf; 451 name = compat->VariableName; 452 vendor = compat->VendorGuid; 453 } else { 454 if (count != sizeof(*del_var)) 455 return -EINVAL; 456 457 name = del_var->VariableName; 458 vendor = del_var->VendorGuid; 459 } 460 461 if (efivar_entry_iter_begin()) 462 return -EINTR; 463 entry = efivar_entry_find(name, vendor, &efivar_sysfs_list, true); 464 if (!entry) 465 err = -EINVAL; 466 else if (__efivar_entry_delete(entry)) 467 err = -EIO; 468 469 if (err) { 470 efivar_entry_iter_end(); 471 return err; 472 } 473 474 if (!entry->scanning) { 475 efivar_entry_iter_end(); 476 efivar_unregister(entry); 477 } else 478 efivar_entry_iter_end(); 479 480 /* It's dead Jim.... */ 481 return count; 482 } 483 484 /** 485 * efivar_create_sysfs_entry - create a new entry in sysfs 486 * @new_var: efivar entry to create 487 * 488 * Returns 0 on success, negative error code on failure 489 */ 490 static int efivar_create_sysfs_entry(struct efivar_entry * new_var)491 efivar_create_sysfs_entry(struct efivar_entry *new_var) 492 { 493 int short_name_size; 494 char *short_name; 495 unsigned long utf8_name_size; 496 efi_char16_t *variable_name = new_var->var.VariableName; 497 int ret; 498 499 /* 500 * Length of the variable bytes in UTF8, plus the '-' separator, 501 * plus the GUID, plus trailing NUL 502 */ 503 utf8_name_size = ucs2_utf8size(variable_name); 504 short_name_size = utf8_name_size + 1 + EFI_VARIABLE_GUID_LEN + 1; 505 506 short_name = kmalloc(short_name_size, GFP_KERNEL); 507 if (!short_name) 508 return -ENOMEM; 509 510 ucs2_as_utf8(short_name, variable_name, short_name_size); 511 512 /* This is ugly, but necessary to separate one vendor's 513 private variables from another's. */ 514 short_name[utf8_name_size] = '-'; 515 efi_guid_to_str(&new_var->var.VendorGuid, 516 short_name + utf8_name_size + 1); 517 518 new_var->kobj.kset = efivars_kset; 519 520 ret = kobject_init_and_add(&new_var->kobj, &efivar_ktype, 521 NULL, "%s", short_name); 522 kfree(short_name); 523 if (ret) { 524 kobject_put(&new_var->kobj); 525 return ret; 526 } 527 528 kobject_uevent(&new_var->kobj, KOBJ_ADD); 529 if (efivar_entry_add(new_var, &efivar_sysfs_list)) { 530 efivar_unregister(new_var); 531 return -EINTR; 532 } 533 534 return 0; 535 } 536 537 static int create_efivars_bin_attributes(void)538 create_efivars_bin_attributes(void) 539 { 540 struct bin_attribute *attr; 541 int error; 542 543 /* new_var */ 544 attr = kzalloc(sizeof(*attr), GFP_KERNEL); 545 if (!attr) 546 return -ENOMEM; 547 548 attr->attr.name = "new_var"; 549 attr->attr.mode = 0200; 550 attr->write = efivar_create; 551 efivars_new_var = attr; 552 553 /* del_var */ 554 attr = kzalloc(sizeof(*attr), GFP_KERNEL); 555 if (!attr) { 556 error = -ENOMEM; 557 goto out_free; 558 } 559 attr->attr.name = "del_var"; 560 attr->attr.mode = 0200; 561 attr->write = efivar_delete; 562 efivars_del_var = attr; 563 564 sysfs_bin_attr_init(efivars_new_var); 565 sysfs_bin_attr_init(efivars_del_var); 566 567 /* Register */ 568 error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_new_var); 569 if (error) { 570 printk(KERN_ERR "efivars: unable to create new_var sysfs file" 571 " due to error %d\n", error); 572 goto out_free; 573 } 574 575 error = sysfs_create_bin_file(&efivars_kset->kobj, efivars_del_var); 576 if (error) { 577 printk(KERN_ERR "efivars: unable to create del_var sysfs file" 578 " due to error %d\n", error); 579 sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var); 580 goto out_free; 581 } 582 583 return 0; 584 out_free: 585 kfree(efivars_del_var); 586 efivars_del_var = NULL; 587 kfree(efivars_new_var); 588 efivars_new_var = NULL; 589 return error; 590 } 591 efivars_sysfs_callback(efi_char16_t * name,efi_guid_t vendor,unsigned long name_size,void * data)592 static int efivars_sysfs_callback(efi_char16_t *name, efi_guid_t vendor, 593 unsigned long name_size, void *data) 594 { 595 struct efivar_entry *entry; 596 597 entry = kzalloc(sizeof(*entry), GFP_KERNEL); 598 if (!entry) 599 return -ENOMEM; 600 601 memcpy(entry->var.VariableName, name, name_size); 602 memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t)); 603 604 efivar_create_sysfs_entry(entry); 605 606 return 0; 607 } 608 efivar_sysfs_destroy(struct efivar_entry * entry,void * data)609 static int efivar_sysfs_destroy(struct efivar_entry *entry, void *data) 610 { 611 int err = efivar_entry_remove(entry); 612 613 if (err) 614 return err; 615 efivar_unregister(entry); 616 return 0; 617 } 618 efivars_sysfs_exit(void)619 static void efivars_sysfs_exit(void) 620 { 621 /* Remove all entries and destroy */ 622 int err; 623 624 err = __efivar_entry_iter(efivar_sysfs_destroy, &efivar_sysfs_list, 625 NULL, NULL); 626 if (err) { 627 pr_err("efivars: Failed to destroy sysfs entries\n"); 628 return; 629 } 630 631 if (efivars_new_var) 632 sysfs_remove_bin_file(&efivars_kset->kobj, efivars_new_var); 633 if (efivars_del_var) 634 sysfs_remove_bin_file(&efivars_kset->kobj, efivars_del_var); 635 kfree(efivars_new_var); 636 kfree(efivars_del_var); 637 kset_unregister(efivars_kset); 638 } 639 efivars_sysfs_init(void)640 static int efivars_sysfs_init(void) 641 { 642 struct kobject *parent_kobj = efivars_kobject(); 643 int error = 0; 644 645 /* No efivars has been registered yet */ 646 if (!parent_kobj || !efivar_supports_writes()) 647 return 0; 648 649 printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION, 650 EFIVARS_DATE); 651 652 efivars_kset = kset_create_and_add("vars", NULL, parent_kobj); 653 if (!efivars_kset) { 654 printk(KERN_ERR "efivars: Subsystem registration failed.\n"); 655 return -ENOMEM; 656 } 657 658 efivar_init(efivars_sysfs_callback, NULL, true, &efivar_sysfs_list); 659 660 error = create_efivars_bin_attributes(); 661 if (error) { 662 efivars_sysfs_exit(); 663 return error; 664 } 665 666 return 0; 667 } 668 669 module_init(efivars_sysfs_init); 670 module_exit(efivars_sysfs_exit); 671