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 9#include <linux/capability.h> 10#include <linux/types.h> 11#include <linux/errno.h> 12#include <linux/init.h> 13#include <linux/mm.h> 14#include <linux/module.h> 15#include <linux/string.h> 16#include <linux/smp.h> 17#include <linux/efi.h> 18#include <linux/sysfs.h> 19#include <linux/device.h> 20#include <linux/slab.h> 21#include <linux/ctype.h> 22#include <linux/ucs2_string.h> 23 24/* Private pointer to registered efivars */ 25static struct efivars *__efivars; 26 27/* 28 * efivars_lock protects three things: 29 * 1) efivarfs_list and efivars_sysfs_list 30 * 2) ->ops calls 31 * 3) (un)registration of __efivars 32 */ 33static DEFINE_SEMAPHORE(efivars_lock); 34 35static bool 36validate_device_path(efi_char16_t *var_name, int match, u8 *buffer, 37 unsigned long len) 38{ 39 struct efi_generic_dev_path *node; 40 int offset = 0; 41 42 node = (struct efi_generic_dev_path *)buffer; 43 44 if (len < sizeof(*node)) 45 return false; 46 47 while (offset <= len - sizeof(*node) && 48 node->length >= sizeof(*node) && 49 node->length <= len - offset) { 50 offset += node->length; 51 52 if ((node->type == EFI_DEV_END_PATH || 53 node->type == EFI_DEV_END_PATH2) && 54 node->sub_type == EFI_DEV_END_ENTIRE) 55 return true; 56 57 node = (struct efi_generic_dev_path *)(buffer + offset); 58 } 59 60 /* 61 * If we're here then either node->length pointed past the end 62 * of the buffer or we reached the end of the buffer without 63 * finding a device path end node. 64 */ 65 return false; 66} 67 68static bool 69validate_boot_order(efi_char16_t *var_name, int match, u8 *buffer, 70 unsigned long len) 71{ 72 /* An array of 16-bit integers */ 73 if ((len % 2) != 0) 74 return false; 75 76 return true; 77} 78 79static bool 80validate_load_option(efi_char16_t *var_name, int match, u8 *buffer, 81 unsigned long len) 82{ 83 u16 filepathlength; 84 int i, desclength = 0, namelen; 85 86 namelen = ucs2_strnlen(var_name, EFI_VAR_NAME_LEN); 87 88 /* Either "Boot" or "Driver" followed by four digits of hex */ 89 for (i = match; i < match+4; i++) { 90 if (var_name[i] > 127 || 91 hex_to_bin(var_name[i] & 0xff) < 0) 92 return true; 93 } 94 95 /* Reject it if there's 4 digits of hex and then further content */ 96 if (namelen > match + 4) 97 return false; 98 99 /* A valid entry must be at least 8 bytes */ 100 if (len < 8) 101 return false; 102 103 filepathlength = buffer[4] | buffer[5] << 8; 104 105 /* 106 * There's no stored length for the description, so it has to be 107 * found by hand 108 */ 109 desclength = ucs2_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2; 110 111 /* Each boot entry must have a descriptor */ 112 if (!desclength) 113 return false; 114 115 /* 116 * If the sum of the length of the description, the claimed filepath 117 * length and the original header are greater than the length of the 118 * variable, it's malformed 119 */ 120 if ((desclength + filepathlength + 6) > len) 121 return false; 122 123 /* 124 * And, finally, check the filepath 125 */ 126 return validate_device_path(var_name, match, buffer + desclength + 6, 127 filepathlength); 128} 129 130static bool 131validate_uint16(efi_char16_t *var_name, int match, u8 *buffer, 132 unsigned long len) 133{ 134 /* A single 16-bit integer */ 135 if (len != 2) 136 return false; 137 138 return true; 139} 140 141static bool 142validate_ascii_string(efi_char16_t *var_name, int match, u8 *buffer, 143 unsigned long len) 144{ 145 int i; 146 147 for (i = 0; i < len; i++) { 148 if (buffer[i] > 127) 149 return false; 150 151 if (buffer[i] == 0) 152 return true; 153 } 154 155 return false; 156} 157 158struct variable_validate { 159 efi_guid_t vendor; 160 char *name; 161 bool (*validate)(efi_char16_t *var_name, int match, u8 *data, 162 unsigned long len); 163}; 164 165/* 166 * This is the list of variables we need to validate, as well as the 167 * whitelist for what we think is safe not to default to immutable. 168 * 169 * If it has a validate() method that's not NULL, it'll go into the 170 * validation routine. If not, it is assumed valid, but still used for 171 * whitelisting. 172 * 173 * Note that it's sorted by {vendor,name}, but globbed names must come after 174 * any other name with the same prefix. 175 */ 176static const struct variable_validate variable_validate[] = { 177 { EFI_GLOBAL_VARIABLE_GUID, "BootNext", validate_uint16 }, 178 { EFI_GLOBAL_VARIABLE_GUID, "BootOrder", validate_boot_order }, 179 { EFI_GLOBAL_VARIABLE_GUID, "Boot*", validate_load_option }, 180 { EFI_GLOBAL_VARIABLE_GUID, "DriverOrder", validate_boot_order }, 181 { EFI_GLOBAL_VARIABLE_GUID, "Driver*", validate_load_option }, 182 { EFI_GLOBAL_VARIABLE_GUID, "ConIn", validate_device_path }, 183 { EFI_GLOBAL_VARIABLE_GUID, "ConInDev", validate_device_path }, 184 { EFI_GLOBAL_VARIABLE_GUID, "ConOut", validate_device_path }, 185 { EFI_GLOBAL_VARIABLE_GUID, "ConOutDev", validate_device_path }, 186 { EFI_GLOBAL_VARIABLE_GUID, "ErrOut", validate_device_path }, 187 { EFI_GLOBAL_VARIABLE_GUID, "ErrOutDev", validate_device_path }, 188 { EFI_GLOBAL_VARIABLE_GUID, "Lang", validate_ascii_string }, 189 { EFI_GLOBAL_VARIABLE_GUID, "OsIndications", NULL }, 190 { EFI_GLOBAL_VARIABLE_GUID, "PlatformLang", validate_ascii_string }, 191 { EFI_GLOBAL_VARIABLE_GUID, "Timeout", validate_uint16 }, 192 { LINUX_EFI_CRASH_GUID, "*", NULL }, 193 { NULL_GUID, "", NULL }, 194}; 195 196/* 197 * Check if @var_name matches the pattern given in @match_name. 198 * 199 * @var_name: an array of @len non-NUL characters. 200 * @match_name: a NUL-terminated pattern string, optionally ending in "*". A 201 * final "*" character matches any trailing characters @var_name, 202 * including the case when there are none left in @var_name. 203 * @match: on output, the number of non-wildcard characters in @match_name 204 * that @var_name matches, regardless of the return value. 205 * @return: whether @var_name fully matches @match_name. 206 */ 207static bool 208variable_matches(const char *var_name, size_t len, const char *match_name, 209 int *match) 210{ 211 for (*match = 0; ; (*match)++) { 212 char c = match_name[*match]; 213 214 switch (c) { 215 case '*': 216 /* Wildcard in @match_name means we've matched. */ 217 return true; 218 219 case '\0': 220 /* @match_name has ended. Has @var_name too? */ 221 return (*match == len); 222 223 default: 224 /* 225 * We've reached a non-wildcard char in @match_name. 226 * Continue only if there's an identical character in 227 * @var_name. 228 */ 229 if (*match < len && c == var_name[*match]) 230 continue; 231 return false; 232 } 233 } 234} 235 236bool 237efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data, 238 unsigned long data_size) 239{ 240 int i; 241 unsigned long utf8_size; 242 u8 *utf8_name; 243 244 utf8_size = ucs2_utf8size(var_name); 245 utf8_name = kmalloc(utf8_size + 1, GFP_KERNEL); 246 if (!utf8_name) 247 return false; 248 249 ucs2_as_utf8(utf8_name, var_name, utf8_size); 250 utf8_name[utf8_size] = '\0'; 251 252 for (i = 0; variable_validate[i].name[0] != '\0'; i++) { 253 const char *name = variable_validate[i].name; 254 int match = 0; 255 256 if (efi_guidcmp(vendor, variable_validate[i].vendor)) 257 continue; 258 259 if (variable_matches(utf8_name, utf8_size+1, name, &match)) { 260 if (variable_validate[i].validate == NULL) 261 break; 262 kfree(utf8_name); 263 return variable_validate[i].validate(var_name, match, 264 data, data_size); 265 } 266 } 267 kfree(utf8_name); 268 return true; 269} 270EXPORT_SYMBOL_GPL(efivar_validate); 271 272bool 273efivar_variable_is_removable(efi_guid_t vendor, const char *var_name, 274 size_t len) 275{ 276 int i; 277 bool found = false; 278 int match = 0; 279 280 /* 281 * Check if our variable is in the validated variables list 282 */ 283 for (i = 0; variable_validate[i].name[0] != '\0'; i++) { 284 if (efi_guidcmp(variable_validate[i].vendor, vendor)) 285 continue; 286 287 if (variable_matches(var_name, len, 288 variable_validate[i].name, &match)) { 289 found = true; 290 break; 291 } 292 } 293 294 /* 295 * If it's in our list, it is removable. 296 */ 297 return found; 298} 299EXPORT_SYMBOL_GPL(efivar_variable_is_removable); 300 301static efi_status_t 302check_var_size(u32 attributes, unsigned long size) 303{ 304 const struct efivar_operations *fops; 305 306 if (!__efivars) 307 return EFI_UNSUPPORTED; 308 309 fops = __efivars->ops; 310 311 if (!fops->query_variable_store) 312 return EFI_UNSUPPORTED; 313 314 return fops->query_variable_store(attributes, size, false); 315} 316 317static efi_status_t 318check_var_size_nonblocking(u32 attributes, unsigned long size) 319{ 320 const struct efivar_operations *fops; 321 322 if (!__efivars) 323 return EFI_UNSUPPORTED; 324 325 fops = __efivars->ops; 326 327 if (!fops->query_variable_store) 328 return EFI_UNSUPPORTED; 329 330 return fops->query_variable_store(attributes, size, true); 331} 332 333static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor, 334 struct list_head *head) 335{ 336 struct efivar_entry *entry, *n; 337 unsigned long strsize1, strsize2; 338 bool found = false; 339 340 strsize1 = ucs2_strsize(variable_name, 1024); 341 list_for_each_entry_safe(entry, n, head, list) { 342 strsize2 = ucs2_strsize(entry->var.VariableName, 1024); 343 if (strsize1 == strsize2 && 344 !memcmp(variable_name, &(entry->var.VariableName), 345 strsize2) && 346 !efi_guidcmp(entry->var.VendorGuid, 347 *vendor)) { 348 found = true; 349 break; 350 } 351 } 352 return found; 353} 354 355/* 356 * Returns the size of variable_name, in bytes, including the 357 * terminating NULL character, or variable_name_size if no NULL 358 * character is found among the first variable_name_size bytes. 359 */ 360static unsigned long var_name_strnsize(efi_char16_t *variable_name, 361 unsigned long variable_name_size) 362{ 363 unsigned long len; 364 efi_char16_t c; 365 366 /* 367 * The variable name is, by definition, a NULL-terminated 368 * string, so make absolutely sure that variable_name_size is 369 * the value we expect it to be. If not, return the real size. 370 */ 371 for (len = 2; len <= variable_name_size; len += sizeof(c)) { 372 c = variable_name[(len / sizeof(c)) - 1]; 373 if (!c) 374 break; 375 } 376 377 return min(len, variable_name_size); 378} 379 380/* 381 * Print a warning when duplicate EFI variables are encountered and 382 * disable the sysfs workqueue since the firmware is buggy. 383 */ 384static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid, 385 unsigned long len16) 386{ 387 size_t i, len8 = len16 / sizeof(efi_char16_t); 388 char *str8; 389 390 str8 = kzalloc(len8, GFP_KERNEL); 391 if (!str8) 392 return; 393 394 for (i = 0; i < len8; i++) 395 str8[i] = str16[i]; 396 397 printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n", 398 str8, vendor_guid); 399 kfree(str8); 400} 401 402/** 403 * efivar_init - build the initial list of EFI variables 404 * @func: callback function to invoke for every variable 405 * @data: function-specific data to pass to @func 406 * @duplicates: error if we encounter duplicates on @head? 407 * @head: initialised head of variable list 408 * 409 * Get every EFI variable from the firmware and invoke @func. @func 410 * should call efivar_entry_add() to build the list of variables. 411 * 412 * Returns 0 on success, or a kernel error code on failure. 413 */ 414int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *), 415 void *data, bool duplicates, struct list_head *head) 416{ 417 const struct efivar_operations *ops; 418 unsigned long variable_name_size = 1024; 419 efi_char16_t *variable_name; 420 efi_status_t status; 421 efi_guid_t vendor_guid; 422 int err = 0; 423 424 if (!__efivars) 425 return -EFAULT; 426 427 ops = __efivars->ops; 428 429 variable_name = kzalloc(variable_name_size, GFP_KERNEL); 430 if (!variable_name) { 431 printk(KERN_ERR "efivars: Memory allocation failed.\n"); 432 return -ENOMEM; 433 } 434 435 if (down_interruptible(&efivars_lock)) { 436 err = -EINTR; 437 goto free; 438 } 439 440 /* 441 * Per EFI spec, the maximum storage allocated for both 442 * the variable name and variable data is 1024 bytes. 443 */ 444 445 do { 446 variable_name_size = 1024; 447 448 status = ops->get_next_variable(&variable_name_size, 449 variable_name, 450 &vendor_guid); 451 switch (status) { 452 case EFI_SUCCESS: 453 if (duplicates) 454 up(&efivars_lock); 455 456 variable_name_size = var_name_strnsize(variable_name, 457 variable_name_size); 458 459 /* 460 * Some firmware implementations return the 461 * same variable name on multiple calls to 462 * get_next_variable(). Terminate the loop 463 * immediately as there is no guarantee that 464 * we'll ever see a different variable name, 465 * and may end up looping here forever. 466 */ 467 if (duplicates && 468 variable_is_present(variable_name, &vendor_guid, 469 head)) { 470 dup_variable_bug(variable_name, &vendor_guid, 471 variable_name_size); 472 status = EFI_NOT_FOUND; 473 } else { 474 err = func(variable_name, vendor_guid, 475 variable_name_size, data); 476 if (err) 477 status = EFI_NOT_FOUND; 478 } 479 480 if (duplicates) { 481 if (down_interruptible(&efivars_lock)) { 482 err = -EINTR; 483 goto free; 484 } 485 } 486 487 break; 488 case EFI_UNSUPPORTED: 489 err = -EOPNOTSUPP; 490 status = EFI_NOT_FOUND; 491 break; 492 case EFI_NOT_FOUND: 493 break; 494 default: 495 printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n", 496 status); 497 status = EFI_NOT_FOUND; 498 break; 499 } 500 501 } while (status != EFI_NOT_FOUND); 502 503 up(&efivars_lock); 504free: 505 kfree(variable_name); 506 507 return err; 508} 509EXPORT_SYMBOL_GPL(efivar_init); 510 511/** 512 * efivar_entry_add - add entry to variable list 513 * @entry: entry to add to list 514 * @head: list head 515 * 516 * Returns 0 on success, or a kernel error code on failure. 517 */ 518int efivar_entry_add(struct efivar_entry *entry, struct list_head *head) 519{ 520 if (down_interruptible(&efivars_lock)) 521 return -EINTR; 522 list_add(&entry->list, head); 523 up(&efivars_lock); 524 525 return 0; 526} 527EXPORT_SYMBOL_GPL(efivar_entry_add); 528 529/** 530 * efivar_entry_remove - remove entry from variable list 531 * @entry: entry to remove from list 532 * 533 * Returns 0 on success, or a kernel error code on failure. 534 */ 535int efivar_entry_remove(struct efivar_entry *entry) 536{ 537 if (down_interruptible(&efivars_lock)) 538 return -EINTR; 539 list_del(&entry->list); 540 up(&efivars_lock); 541 542 return 0; 543} 544EXPORT_SYMBOL_GPL(efivar_entry_remove); 545 546/* 547 * efivar_entry_list_del_unlock - remove entry from variable list 548 * @entry: entry to remove 549 * 550 * Remove @entry from the variable list and release the list lock. 551 * 552 * NOTE: slightly weird locking semantics here - we expect to be 553 * called with the efivars lock already held, and we release it before 554 * returning. This is because this function is usually called after 555 * set_variable() while the lock is still held. 556 */ 557static void efivar_entry_list_del_unlock(struct efivar_entry *entry) 558{ 559 list_del(&entry->list); 560 up(&efivars_lock); 561} 562 563/** 564 * __efivar_entry_delete - delete an EFI variable 565 * @entry: entry containing EFI variable to delete 566 * 567 * Delete the variable from the firmware but leave @entry on the 568 * variable list. 569 * 570 * This function differs from efivar_entry_delete() because it does 571 * not remove @entry from the variable list. Also, it is safe to be 572 * called from within a efivar_entry_iter_begin() and 573 * efivar_entry_iter_end() region, unlike efivar_entry_delete(). 574 * 575 * Returns 0 on success, or a converted EFI status code if 576 * set_variable() fails. 577 */ 578int __efivar_entry_delete(struct efivar_entry *entry) 579{ 580 efi_status_t status; 581 582 if (!__efivars) 583 return -EINVAL; 584 585 status = __efivars->ops->set_variable(entry->var.VariableName, 586 &entry->var.VendorGuid, 587 0, 0, NULL); 588 589 return efi_status_to_err(status); 590} 591EXPORT_SYMBOL_GPL(__efivar_entry_delete); 592 593/** 594 * efivar_entry_delete - delete variable and remove entry from list 595 * @entry: entry containing variable to delete 596 * 597 * Delete the variable from the firmware and remove @entry from the 598 * variable list. It is the caller's responsibility to free @entry 599 * once we return. 600 * 601 * Returns 0 on success, -EINTR if we can't grab the semaphore, 602 * converted EFI status code if set_variable() fails. 603 */ 604int efivar_entry_delete(struct efivar_entry *entry) 605{ 606 const struct efivar_operations *ops; 607 efi_status_t status; 608 609 if (down_interruptible(&efivars_lock)) 610 return -EINTR; 611 612 if (!__efivars) { 613 up(&efivars_lock); 614 return -EINVAL; 615 } 616 ops = __efivars->ops; 617 status = ops->set_variable(entry->var.VariableName, 618 &entry->var.VendorGuid, 619 0, 0, NULL); 620 if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND)) { 621 up(&efivars_lock); 622 return efi_status_to_err(status); 623 } 624 625 efivar_entry_list_del_unlock(entry); 626 return 0; 627} 628EXPORT_SYMBOL_GPL(efivar_entry_delete); 629 630/** 631 * efivar_entry_set - call set_variable() 632 * @entry: entry containing the EFI variable to write 633 * @attributes: variable attributes 634 * @size: size of @data buffer 635 * @data: buffer containing variable data 636 * @head: head of variable list 637 * 638 * Calls set_variable() for an EFI variable. If creating a new EFI 639 * variable, this function is usually followed by efivar_entry_add(). 640 * 641 * Before writing the variable, the remaining EFI variable storage 642 * space is checked to ensure there is enough room available. 643 * 644 * If @head is not NULL a lookup is performed to determine whether 645 * the entry is already on the list. 646 * 647 * Returns 0 on success, -EINTR if we can't grab the semaphore, 648 * -EEXIST if a lookup is performed and the entry already exists on 649 * the list, or a converted EFI status code if set_variable() fails. 650 */ 651int efivar_entry_set(struct efivar_entry *entry, u32 attributes, 652 unsigned long size, void *data, struct list_head *head) 653{ 654 const struct efivar_operations *ops; 655 efi_status_t status; 656 efi_char16_t *name = entry->var.VariableName; 657 efi_guid_t vendor = entry->var.VendorGuid; 658 659 if (down_interruptible(&efivars_lock)) 660 return -EINTR; 661 662 if (!__efivars) { 663 up(&efivars_lock); 664 return -EINVAL; 665 } 666 ops = __efivars->ops; 667 if (head && efivar_entry_find(name, vendor, head, false)) { 668 up(&efivars_lock); 669 return -EEXIST; 670 } 671 672 status = check_var_size(attributes, size + ucs2_strsize(name, 1024)); 673 if (status == EFI_SUCCESS || status == EFI_UNSUPPORTED) 674 status = ops->set_variable(name, &vendor, 675 attributes, size, data); 676 677 up(&efivars_lock); 678 679 return efi_status_to_err(status); 680 681} 682EXPORT_SYMBOL_GPL(efivar_entry_set); 683 684/* 685 * efivar_entry_set_nonblocking - call set_variable_nonblocking() 686 * 687 * This function is guaranteed to not block and is suitable for calling 688 * from crash/panic handlers. 689 * 690 * Crucially, this function will not block if it cannot acquire 691 * efivars_lock. Instead, it returns -EBUSY. 692 */ 693static int 694efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor, 695 u32 attributes, unsigned long size, void *data) 696{ 697 const struct efivar_operations *ops; 698 efi_status_t status; 699 700 if (down_trylock(&efivars_lock)) 701 return -EBUSY; 702 703 if (!__efivars) { 704 up(&efivars_lock); 705 return -EINVAL; 706 } 707 708 status = check_var_size_nonblocking(attributes, 709 size + ucs2_strsize(name, 1024)); 710 if (status != EFI_SUCCESS) { 711 up(&efivars_lock); 712 return -ENOSPC; 713 } 714 715 ops = __efivars->ops; 716 status = ops->set_variable_nonblocking(name, &vendor, attributes, 717 size, data); 718 719 up(&efivars_lock); 720 return efi_status_to_err(status); 721} 722 723/** 724 * efivar_entry_set_safe - call set_variable() if enough space in firmware 725 * @name: buffer containing the variable name 726 * @vendor: variable vendor guid 727 * @attributes: variable attributes 728 * @block: can we block in this context? 729 * @size: size of @data buffer 730 * @data: buffer containing variable data 731 * 732 * Ensures there is enough free storage in the firmware for this variable, and 733 * if so, calls set_variable(). If creating a new EFI variable, this function 734 * is usually followed by efivar_entry_add(). 735 * 736 * Returns 0 on success, -ENOSPC if the firmware does not have enough 737 * space for set_variable() to succeed, or a converted EFI status code 738 * if set_variable() fails. 739 */ 740int efivar_entry_set_safe(efi_char16_t *name, efi_guid_t vendor, u32 attributes, 741 bool block, unsigned long size, void *data) 742{ 743 const struct efivar_operations *ops; 744 efi_status_t status; 745 unsigned long varsize; 746 747 if (!__efivars) 748 return -EINVAL; 749 750 ops = __efivars->ops; 751 if (!ops->query_variable_store) 752 return -ENOSYS; 753 754 /* 755 * If the EFI variable backend provides a non-blocking 756 * ->set_variable() operation and we're in a context where we 757 * cannot block, then we need to use it to avoid live-locks, 758 * since the implication is that the regular ->set_variable() 759 * will block. 760 * 761 * If no ->set_variable_nonblocking() is provided then 762 * ->set_variable() is assumed to be non-blocking. 763 */ 764 if (!block && ops->set_variable_nonblocking) 765 return efivar_entry_set_nonblocking(name, vendor, attributes, 766 size, data); 767 768 varsize = size + ucs2_strsize(name, 1024); 769 if (!block) { 770 if (down_trylock(&efivars_lock)) 771 return -EBUSY; 772 status = check_var_size_nonblocking(attributes, varsize); 773 } else { 774 if (down_interruptible(&efivars_lock)) 775 return -EINTR; 776 status = check_var_size(attributes, varsize); 777 } 778 779 if (status != EFI_SUCCESS) { 780 up(&efivars_lock); 781 return -ENOSPC; 782 } 783 784 status = ops->set_variable(name, &vendor, attributes, size, data); 785 786 up(&efivars_lock); 787 788 return efi_status_to_err(status); 789} 790EXPORT_SYMBOL_GPL(efivar_entry_set_safe); 791 792/** 793 * efivar_entry_find - search for an entry 794 * @name: the EFI variable name 795 * @guid: the EFI variable vendor's guid 796 * @head: head of the variable list 797 * @remove: should we remove the entry from the list? 798 * 799 * Search for an entry on the variable list that has the EFI variable 800 * name @name and vendor guid @guid. If an entry is found on the list 801 * and @remove is true, the entry is removed from the list. 802 * 803 * The caller MUST call efivar_entry_iter_begin() and 804 * efivar_entry_iter_end() before and after the invocation of this 805 * function, respectively. 806 * 807 * Returns the entry if found on the list, %NULL otherwise. 808 */ 809struct efivar_entry *efivar_entry_find(efi_char16_t *name, efi_guid_t guid, 810 struct list_head *head, bool remove) 811{ 812 struct efivar_entry *entry, *n; 813 int strsize1, strsize2; 814 bool found = false; 815 816 list_for_each_entry_safe(entry, n, head, list) { 817 strsize1 = ucs2_strsize(name, 1024); 818 strsize2 = ucs2_strsize(entry->var.VariableName, 1024); 819 if (strsize1 == strsize2 && 820 !memcmp(name, &(entry->var.VariableName), strsize1) && 821 !efi_guidcmp(guid, entry->var.VendorGuid)) { 822 found = true; 823 break; 824 } 825 } 826 827 if (!found) 828 return NULL; 829 830 if (remove) { 831 if (entry->scanning) { 832 /* 833 * The entry will be deleted 834 * after scanning is completed. 835 */ 836 entry->deleting = true; 837 } else 838 list_del(&entry->list); 839 } 840 841 return entry; 842} 843EXPORT_SYMBOL_GPL(efivar_entry_find); 844 845/** 846 * efivar_entry_size - obtain the size of a variable 847 * @entry: entry for this variable 848 * @size: location to store the variable's size 849 */ 850int efivar_entry_size(struct efivar_entry *entry, unsigned long *size) 851{ 852 const struct efivar_operations *ops; 853 efi_status_t status; 854 855 *size = 0; 856 857 if (down_interruptible(&efivars_lock)) 858 return -EINTR; 859 if (!__efivars) { 860 up(&efivars_lock); 861 return -EINVAL; 862 } 863 ops = __efivars->ops; 864 status = ops->get_variable(entry->var.VariableName, 865 &entry->var.VendorGuid, NULL, size, NULL); 866 up(&efivars_lock); 867 868 if (status != EFI_BUFFER_TOO_SMALL) 869 return efi_status_to_err(status); 870 871 return 0; 872} 873EXPORT_SYMBOL_GPL(efivar_entry_size); 874 875/** 876 * __efivar_entry_get - call get_variable() 877 * @entry: read data for this variable 878 * @attributes: variable attributes 879 * @size: size of @data buffer 880 * @data: buffer to store variable data 881 * 882 * The caller MUST call efivar_entry_iter_begin() and 883 * efivar_entry_iter_end() before and after the invocation of this 884 * function, respectively. 885 */ 886int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes, 887 unsigned long *size, void *data) 888{ 889 efi_status_t status; 890 891 if (!__efivars) 892 return -EINVAL; 893 894 status = __efivars->ops->get_variable(entry->var.VariableName, 895 &entry->var.VendorGuid, 896 attributes, size, data); 897 898 return efi_status_to_err(status); 899} 900EXPORT_SYMBOL_GPL(__efivar_entry_get); 901 902/** 903 * efivar_entry_get - call get_variable() 904 * @entry: read data for this variable 905 * @attributes: variable attributes 906 * @size: size of @data buffer 907 * @data: buffer to store variable data 908 */ 909int efivar_entry_get(struct efivar_entry *entry, u32 *attributes, 910 unsigned long *size, void *data) 911{ 912 efi_status_t status; 913 914 if (down_interruptible(&efivars_lock)) 915 return -EINTR; 916 917 if (!__efivars) { 918 up(&efivars_lock); 919 return -EINVAL; 920 } 921 922 status = __efivars->ops->get_variable(entry->var.VariableName, 923 &entry->var.VendorGuid, 924 attributes, size, data); 925 up(&efivars_lock); 926 927 return efi_status_to_err(status); 928} 929EXPORT_SYMBOL_GPL(efivar_entry_get); 930 931/** 932 * efivar_entry_set_get_size - call set_variable() and get new size (atomic) 933 * @entry: entry containing variable to set and get 934 * @attributes: attributes of variable to be written 935 * @size: size of data buffer 936 * @data: buffer containing data to write 937 * @set: did the set_variable() call succeed? 938 * 939 * This is a pretty special (complex) function. See efivarfs_file_write(). 940 * 941 * Atomically call set_variable() for @entry and if the call is 942 * successful, return the new size of the variable from get_variable() 943 * in @size. The success of set_variable() is indicated by @set. 944 * 945 * Returns 0 on success, -EINVAL if the variable data is invalid, 946 * -ENOSPC if the firmware does not have enough available space, or a 947 * converted EFI status code if either of set_variable() or 948 * get_variable() fail. 949 * 950 * If the EFI variable does not exist when calling set_variable() 951 * (EFI_NOT_FOUND), @entry is removed from the variable list. 952 */ 953int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes, 954 unsigned long *size, void *data, bool *set) 955{ 956 const struct efivar_operations *ops; 957 efi_char16_t *name = entry->var.VariableName; 958 efi_guid_t *vendor = &entry->var.VendorGuid; 959 efi_status_t status; 960 int err; 961 962 *set = false; 963 964 if (efivar_validate(*vendor, name, data, *size) == false) 965 return -EINVAL; 966 967 /* 968 * The lock here protects the get_variable call, the conditional 969 * set_variable call, and removal of the variable from the efivars 970 * list (in the case of an authenticated delete). 971 */ 972 if (down_interruptible(&efivars_lock)) 973 return -EINTR; 974 975 if (!__efivars) { 976 err = -EINVAL; 977 goto out; 978 } 979 980 /* 981 * Ensure that the available space hasn't shrunk below the safe level 982 */ 983 status = check_var_size(attributes, *size + ucs2_strsize(name, 1024)); 984 if (status != EFI_SUCCESS) { 985 if (status != EFI_UNSUPPORTED) { 986 err = efi_status_to_err(status); 987 goto out; 988 } 989 990 if (*size > 65536) { 991 err = -ENOSPC; 992 goto out; 993 } 994 } 995 996 ops = __efivars->ops; 997 998 status = ops->set_variable(name, vendor, attributes, *size, data); 999 if (status != EFI_SUCCESS) { 1000 err = efi_status_to_err(status); 1001 goto out; 1002 } 1003 1004 *set = true; 1005 1006 /* 1007 * Writing to the variable may have caused a change in size (which 1008 * could either be an append or an overwrite), or the variable to be 1009 * deleted. Perform a GetVariable() so we can tell what actually 1010 * happened. 1011 */ 1012 *size = 0; 1013 status = ops->get_variable(entry->var.VariableName, 1014 &entry->var.VendorGuid, 1015 NULL, size, NULL); 1016 1017 if (status == EFI_NOT_FOUND) 1018 efivar_entry_list_del_unlock(entry); 1019 else 1020 up(&efivars_lock); 1021 1022 if (status && status != EFI_BUFFER_TOO_SMALL) 1023 return efi_status_to_err(status); 1024 1025 return 0; 1026 1027out: 1028 up(&efivars_lock); 1029 return err; 1030 1031} 1032EXPORT_SYMBOL_GPL(efivar_entry_set_get_size); 1033 1034/** 1035 * efivar_entry_iter_begin - begin iterating the variable list 1036 * 1037 * Lock the variable list to prevent entry insertion and removal until 1038 * efivar_entry_iter_end() is called. This function is usually used in 1039 * conjunction with __efivar_entry_iter() or efivar_entry_iter(). 1040 */ 1041int efivar_entry_iter_begin(void) 1042{ 1043 return down_interruptible(&efivars_lock); 1044} 1045EXPORT_SYMBOL_GPL(efivar_entry_iter_begin); 1046 1047/** 1048 * efivar_entry_iter_end - finish iterating the variable list 1049 * 1050 * Unlock the variable list and allow modifications to the list again. 1051 */ 1052void efivar_entry_iter_end(void) 1053{ 1054 up(&efivars_lock); 1055} 1056EXPORT_SYMBOL_GPL(efivar_entry_iter_end); 1057 1058/** 1059 * __efivar_entry_iter - iterate over variable list 1060 * @func: callback function 1061 * @head: head of the variable list 1062 * @data: function-specific data to pass to callback 1063 * @prev: entry to begin iterating from 1064 * 1065 * Iterate over the list of EFI variables and call @func with every 1066 * entry on the list. It is safe for @func to remove entries in the 1067 * list via efivar_entry_delete(). 1068 * 1069 * You MUST call efivar_entry_iter_begin() before this function, and 1070 * efivar_entry_iter_end() afterwards. 1071 * 1072 * It is possible to begin iteration from an arbitrary entry within 1073 * the list by passing @prev. @prev is updated on return to point to 1074 * the last entry passed to @func. To begin iterating from the 1075 * beginning of the list @prev must be %NULL. 1076 * 1077 * The restrictions for @func are the same as documented for 1078 * efivar_entry_iter(). 1079 */ 1080int __efivar_entry_iter(int (*func)(struct efivar_entry *, void *), 1081 struct list_head *head, void *data, 1082 struct efivar_entry **prev) 1083{ 1084 struct efivar_entry *entry, *n; 1085 int err = 0; 1086 1087 if (!prev || !*prev) { 1088 list_for_each_entry_safe(entry, n, head, list) { 1089 err = func(entry, data); 1090 if (err) 1091 break; 1092 } 1093 1094 if (prev) 1095 *prev = entry; 1096 1097 return err; 1098 } 1099 1100 1101 list_for_each_entry_safe_continue((*prev), n, head, list) { 1102 err = func(*prev, data); 1103 if (err) 1104 break; 1105 } 1106 1107 return err; 1108} 1109EXPORT_SYMBOL_GPL(__efivar_entry_iter); 1110 1111/** 1112 * efivar_entry_iter - iterate over variable list 1113 * @func: callback function 1114 * @head: head of variable list 1115 * @data: function-specific data to pass to callback 1116 * 1117 * Iterate over the list of EFI variables and call @func with every 1118 * entry on the list. It is safe for @func to remove entries in the 1119 * list via efivar_entry_delete() while iterating. 1120 * 1121 * Some notes for the callback function: 1122 * - a non-zero return value indicates an error and terminates the loop 1123 * - @func is called from atomic context 1124 */ 1125int efivar_entry_iter(int (*func)(struct efivar_entry *, void *), 1126 struct list_head *head, void *data) 1127{ 1128 int err = 0; 1129 1130 err = efivar_entry_iter_begin(); 1131 if (err) 1132 return err; 1133 err = __efivar_entry_iter(func, head, data, NULL); 1134 efivar_entry_iter_end(); 1135 1136 return err; 1137} 1138EXPORT_SYMBOL_GPL(efivar_entry_iter); 1139 1140/** 1141 * efivars_kobject - get the kobject for the registered efivars 1142 * 1143 * If efivars_register() has not been called we return NULL, 1144 * otherwise return the kobject used at registration time. 1145 */ 1146struct kobject *efivars_kobject(void) 1147{ 1148 if (!__efivars) 1149 return NULL; 1150 1151 return __efivars->kobject; 1152} 1153EXPORT_SYMBOL_GPL(efivars_kobject); 1154 1155/** 1156 * efivars_register - register an efivars 1157 * @efivars: efivars to register 1158 * @ops: efivars operations 1159 * @kobject: @efivars-specific kobject 1160 * 1161 * Only a single efivars can be registered at any time. 1162 */ 1163int efivars_register(struct efivars *efivars, 1164 const struct efivar_operations *ops, 1165 struct kobject *kobject) 1166{ 1167 if (down_interruptible(&efivars_lock)) 1168 return -EINTR; 1169 1170 efivars->ops = ops; 1171 efivars->kobject = kobject; 1172 1173 __efivars = efivars; 1174 1175 pr_info("Registered efivars operations\n"); 1176 1177 up(&efivars_lock); 1178 1179 return 0; 1180} 1181EXPORT_SYMBOL_GPL(efivars_register); 1182 1183/** 1184 * efivars_unregister - unregister an efivars 1185 * @efivars: efivars to unregister 1186 * 1187 * The caller must have already removed every entry from the list, 1188 * failure to do so is an error. 1189 */ 1190int efivars_unregister(struct efivars *efivars) 1191{ 1192 int rv; 1193 1194 if (down_interruptible(&efivars_lock)) 1195 return -EINTR; 1196 1197 if (!__efivars) { 1198 printk(KERN_ERR "efivars not registered\n"); 1199 rv = -EINVAL; 1200 goto out; 1201 } 1202 1203 if (__efivars != efivars) { 1204 rv = -EINVAL; 1205 goto out; 1206 } 1207 1208 pr_info("Unregistered efivars operations\n"); 1209 __efivars = NULL; 1210 1211 rv = 0; 1212out: 1213 up(&efivars_lock); 1214 return rv; 1215} 1216EXPORT_SYMBOL_GPL(efivars_unregister); 1217 1218int efivar_supports_writes(void) 1219{ 1220 return __efivars && __efivars->ops->set_variable; 1221} 1222EXPORT_SYMBOL_GPL(efivar_supports_writes); 1223