1 /* 2 * Originally from efivars.c 3 * 4 * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com> 5 * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com> 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License as published by 9 * the Free Software Foundation; either version 2 of the License, or 10 * (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, write to the Free Software 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 */ 21 22 #include <linux/capability.h> 23 #include <linux/types.h> 24 #include <linux/errno.h> 25 #include <linux/init.h> 26 #include <linux/mm.h> 27 #include <linux/module.h> 28 #include <linux/string.h> 29 #include <linux/smp.h> 30 #include <linux/efi.h> 31 #include <linux/sysfs.h> 32 #include <linux/device.h> 33 #include <linux/slab.h> 34 #include <linux/ctype.h> 35 #include <linux/ucs2_string.h> 36 37 /* Private pointer to registered efivars */ 38 static struct efivars *__efivars; 39 40 /* 41 * efivars_lock protects three things: 42 * 1) efivarfs_list and efivars_sysfs_list 43 * 2) ->ops calls 44 * 3) (un)registration of __efivars 45 */ 46 static DEFINE_SEMAPHORE(efivars_lock); 47 48 static bool efivar_wq_enabled = true; 49 DECLARE_WORK(efivar_work, NULL); 50 EXPORT_SYMBOL_GPL(efivar_work); 51 52 static bool 53 validate_device_path(efi_char16_t *var_name, int match, u8 *buffer, 54 unsigned long len) 55 { 56 struct efi_generic_dev_path *node; 57 int offset = 0; 58 59 node = (struct efi_generic_dev_path *)buffer; 60 61 if (len < sizeof(*node)) 62 return false; 63 64 while (offset <= len - sizeof(*node) && 65 node->length >= sizeof(*node) && 66 node->length <= len - offset) { 67 offset += node->length; 68 69 if ((node->type == EFI_DEV_END_PATH || 70 node->type == EFI_DEV_END_PATH2) && 71 node->sub_type == EFI_DEV_END_ENTIRE) 72 return true; 73 74 node = (struct efi_generic_dev_path *)(buffer + offset); 75 } 76 77 /* 78 * If we're here then either node->length pointed past the end 79 * of the buffer or we reached the end of the buffer without 80 * finding a device path end node. 81 */ 82 return false; 83 } 84 85 static bool 86 validate_boot_order(efi_char16_t *var_name, int match, u8 *buffer, 87 unsigned long len) 88 { 89 /* An array of 16-bit integers */ 90 if ((len % 2) != 0) 91 return false; 92 93 return true; 94 } 95 96 static bool 97 validate_load_option(efi_char16_t *var_name, int match, u8 *buffer, 98 unsigned long len) 99 { 100 u16 filepathlength; 101 int i, desclength = 0, namelen; 102 103 namelen = ucs2_strnlen(var_name, EFI_VAR_NAME_LEN); 104 105 /* Either "Boot" or "Driver" followed by four digits of hex */ 106 for (i = match; i < match+4; i++) { 107 if (var_name[i] > 127 || 108 hex_to_bin(var_name[i] & 0xff) < 0) 109 return true; 110 } 111 112 /* Reject it if there's 4 digits of hex and then further content */ 113 if (namelen > match + 4) 114 return false; 115 116 /* A valid entry must be at least 8 bytes */ 117 if (len < 8) 118 return false; 119 120 filepathlength = buffer[4] | buffer[5] << 8; 121 122 /* 123 * There's no stored length for the description, so it has to be 124 * found by hand 125 */ 126 desclength = ucs2_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2; 127 128 /* Each boot entry must have a descriptor */ 129 if (!desclength) 130 return false; 131 132 /* 133 * If the sum of the length of the description, the claimed filepath 134 * length and the original header are greater than the length of the 135 * variable, it's malformed 136 */ 137 if ((desclength + filepathlength + 6) > len) 138 return false; 139 140 /* 141 * And, finally, check the filepath 142 */ 143 return validate_device_path(var_name, match, buffer + desclength + 6, 144 filepathlength); 145 } 146 147 static bool 148 validate_uint16(efi_char16_t *var_name, int match, u8 *buffer, 149 unsigned long len) 150 { 151 /* A single 16-bit integer */ 152 if (len != 2) 153 return false; 154 155 return true; 156 } 157 158 static bool 159 validate_ascii_string(efi_char16_t *var_name, int match, u8 *buffer, 160 unsigned long len) 161 { 162 int i; 163 164 for (i = 0; i < len; i++) { 165 if (buffer[i] > 127) 166 return false; 167 168 if (buffer[i] == 0) 169 return true; 170 } 171 172 return false; 173 } 174 175 struct variable_validate { 176 efi_guid_t vendor; 177 char *name; 178 bool (*validate)(efi_char16_t *var_name, int match, u8 *data, 179 unsigned long len); 180 }; 181 182 /* 183 * This is the list of variables we need to validate, as well as the 184 * whitelist for what we think is safe not to default to immutable. 185 * 186 * If it has a validate() method that's not NULL, it'll go into the 187 * validation routine. If not, it is assumed valid, but still used for 188 * whitelisting. 189 * 190 * Note that it's sorted by {vendor,name}, but globbed names must come after 191 * any other name with the same prefix. 192 */ 193 static const struct variable_validate variable_validate[] = { 194 { EFI_GLOBAL_VARIABLE_GUID, "BootNext", validate_uint16 }, 195 { EFI_GLOBAL_VARIABLE_GUID, "BootOrder", validate_boot_order }, 196 { EFI_GLOBAL_VARIABLE_GUID, "Boot*", validate_load_option }, 197 { EFI_GLOBAL_VARIABLE_GUID, "DriverOrder", validate_boot_order }, 198 { EFI_GLOBAL_VARIABLE_GUID, "Driver*", validate_load_option }, 199 { EFI_GLOBAL_VARIABLE_GUID, "ConIn", validate_device_path }, 200 { EFI_GLOBAL_VARIABLE_GUID, "ConInDev", validate_device_path }, 201 { EFI_GLOBAL_VARIABLE_GUID, "ConOut", validate_device_path }, 202 { EFI_GLOBAL_VARIABLE_GUID, "ConOutDev", validate_device_path }, 203 { EFI_GLOBAL_VARIABLE_GUID, "ErrOut", validate_device_path }, 204 { EFI_GLOBAL_VARIABLE_GUID, "ErrOutDev", validate_device_path }, 205 { EFI_GLOBAL_VARIABLE_GUID, "Lang", validate_ascii_string }, 206 { EFI_GLOBAL_VARIABLE_GUID, "OsIndications", NULL }, 207 { EFI_GLOBAL_VARIABLE_GUID, "PlatformLang", validate_ascii_string }, 208 { EFI_GLOBAL_VARIABLE_GUID, "Timeout", validate_uint16 }, 209 { LINUX_EFI_CRASH_GUID, "*", NULL }, 210 { NULL_GUID, "", NULL }, 211 }; 212 213 /* 214 * Check if @var_name matches the pattern given in @match_name. 215 * 216 * @var_name: an array of @len non-NUL characters. 217 * @match_name: a NUL-terminated pattern string, optionally ending in "*". A 218 * final "*" character matches any trailing characters @var_name, 219 * including the case when there are none left in @var_name. 220 * @match: on output, the number of non-wildcard characters in @match_name 221 * that @var_name matches, regardless of the return value. 222 * @return: whether @var_name fully matches @match_name. 223 */ 224 static bool 225 variable_matches(const char *var_name, size_t len, const char *match_name, 226 int *match) 227 { 228 for (*match = 0; ; (*match)++) { 229 char c = match_name[*match]; 230 231 switch (c) { 232 case '*': 233 /* Wildcard in @match_name means we've matched. */ 234 return true; 235 236 case '\0': 237 /* @match_name has ended. Has @var_name too? */ 238 return (*match == len); 239 240 default: 241 /* 242 * We've reached a non-wildcard char in @match_name. 243 * Continue only if there's an identical character in 244 * @var_name. 245 */ 246 if (*match < len && c == var_name[*match]) 247 continue; 248 return false; 249 } 250 } 251 } 252 253 bool 254 efivar_validate(efi_guid_t vendor, efi_char16_t *var_name, u8 *data, 255 unsigned long data_size) 256 { 257 int i; 258 unsigned long utf8_size; 259 u8 *utf8_name; 260 261 utf8_size = ucs2_utf8size(var_name); 262 utf8_name = kmalloc(utf8_size + 1, GFP_KERNEL); 263 if (!utf8_name) 264 return false; 265 266 ucs2_as_utf8(utf8_name, var_name, utf8_size); 267 utf8_name[utf8_size] = '\0'; 268 269 for (i = 0; variable_validate[i].name[0] != '\0'; i++) { 270 const char *name = variable_validate[i].name; 271 int match = 0; 272 273 if (efi_guidcmp(vendor, variable_validate[i].vendor)) 274 continue; 275 276 if (variable_matches(utf8_name, utf8_size+1, name, &match)) { 277 if (variable_validate[i].validate == NULL) 278 break; 279 kfree(utf8_name); 280 return variable_validate[i].validate(var_name, match, 281 data, data_size); 282 } 283 } 284 kfree(utf8_name); 285 return true; 286 } 287 EXPORT_SYMBOL_GPL(efivar_validate); 288 289 bool 290 efivar_variable_is_removable(efi_guid_t vendor, const char *var_name, 291 size_t len) 292 { 293 int i; 294 bool found = false; 295 int match = 0; 296 297 /* 298 * Check if our variable is in the validated variables list 299 */ 300 for (i = 0; variable_validate[i].name[0] != '\0'; i++) { 301 if (efi_guidcmp(variable_validate[i].vendor, vendor)) 302 continue; 303 304 if (variable_matches(var_name, len, 305 variable_validate[i].name, &match)) { 306 found = true; 307 break; 308 } 309 } 310 311 /* 312 * If it's in our list, it is removable. 313 */ 314 return found; 315 } 316 EXPORT_SYMBOL_GPL(efivar_variable_is_removable); 317 318 static efi_status_t 319 check_var_size(u32 attributes, unsigned long size) 320 { 321 const struct efivar_operations *fops; 322 323 if (!__efivars) 324 return EFI_UNSUPPORTED; 325 326 fops = __efivars->ops; 327 328 if (!fops->query_variable_store) 329 return EFI_UNSUPPORTED; 330 331 return fops->query_variable_store(attributes, size, false); 332 } 333 334 static efi_status_t 335 check_var_size_nonblocking(u32 attributes, unsigned long size) 336 { 337 const struct efivar_operations *fops; 338 339 if (!__efivars) 340 return EFI_UNSUPPORTED; 341 342 fops = __efivars->ops; 343 344 if (!fops->query_variable_store) 345 return EFI_UNSUPPORTED; 346 347 return fops->query_variable_store(attributes, size, true); 348 } 349 350 static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor, 351 struct list_head *head) 352 { 353 struct efivar_entry *entry, *n; 354 unsigned long strsize1, strsize2; 355 bool found = false; 356 357 strsize1 = ucs2_strsize(variable_name, 1024); 358 list_for_each_entry_safe(entry, n, head, list) { 359 strsize2 = ucs2_strsize(entry->var.VariableName, 1024); 360 if (strsize1 == strsize2 && 361 !memcmp(variable_name, &(entry->var.VariableName), 362 strsize2) && 363 !efi_guidcmp(entry->var.VendorGuid, 364 *vendor)) { 365 found = true; 366 break; 367 } 368 } 369 return found; 370 } 371 372 /* 373 * Returns the size of variable_name, in bytes, including the 374 * terminating NULL character, or variable_name_size if no NULL 375 * character is found among the first variable_name_size bytes. 376 */ 377 static unsigned long var_name_strnsize(efi_char16_t *variable_name, 378 unsigned long variable_name_size) 379 { 380 unsigned long len; 381 efi_char16_t c; 382 383 /* 384 * The variable name is, by definition, a NULL-terminated 385 * string, so make absolutely sure that variable_name_size is 386 * the value we expect it to be. If not, return the real size. 387 */ 388 for (len = 2; len <= variable_name_size; len += sizeof(c)) { 389 c = variable_name[(len / sizeof(c)) - 1]; 390 if (!c) 391 break; 392 } 393 394 return min(len, variable_name_size); 395 } 396 397 /* 398 * Print a warning when duplicate EFI variables are encountered and 399 * disable the sysfs workqueue since the firmware is buggy. 400 */ 401 static void dup_variable_bug(efi_char16_t *str16, efi_guid_t *vendor_guid, 402 unsigned long len16) 403 { 404 size_t i, len8 = len16 / sizeof(efi_char16_t); 405 char *str8; 406 407 /* 408 * Disable the workqueue since the algorithm it uses for 409 * detecting new variables won't work with this buggy 410 * implementation of GetNextVariableName(). 411 */ 412 efivar_wq_enabled = false; 413 414 str8 = kzalloc(len8, GFP_KERNEL); 415 if (!str8) 416 return; 417 418 for (i = 0; i < len8; i++) 419 str8[i] = str16[i]; 420 421 printk(KERN_WARNING "efivars: duplicate variable: %s-%pUl\n", 422 str8, vendor_guid); 423 kfree(str8); 424 } 425 426 /** 427 * efivar_init - build the initial list of EFI variables 428 * @func: callback function to invoke for every variable 429 * @data: function-specific data to pass to @func 430 * @atomic: do we need to execute the @func-loop atomically? 431 * @duplicates: error if we encounter duplicates on @head? 432 * @head: initialised head of variable list 433 * 434 * Get every EFI variable from the firmware and invoke @func. @func 435 * should call efivar_entry_add() to build the list of variables. 436 * 437 * Returns 0 on success, or a kernel error code on failure. 438 */ 439 int efivar_init(int (*func)(efi_char16_t *, efi_guid_t, unsigned long, void *), 440 void *data, bool duplicates, struct list_head *head) 441 { 442 const struct efivar_operations *ops; 443 unsigned long variable_name_size = 1024; 444 efi_char16_t *variable_name; 445 efi_status_t status; 446 efi_guid_t vendor_guid; 447 int err = 0; 448 449 if (!__efivars) 450 return -EFAULT; 451 452 ops = __efivars->ops; 453 454 variable_name = kzalloc(variable_name_size, GFP_KERNEL); 455 if (!variable_name) { 456 printk(KERN_ERR "efivars: Memory allocation failed.\n"); 457 return -ENOMEM; 458 } 459 460 if (down_interruptible(&efivars_lock)) { 461 err = -EINTR; 462 goto free; 463 } 464 465 /* 466 * Per EFI spec, the maximum storage allocated for both 467 * the variable name and variable data is 1024 bytes. 468 */ 469 470 do { 471 variable_name_size = 1024; 472 473 status = ops->get_next_variable(&variable_name_size, 474 variable_name, 475 &vendor_guid); 476 switch (status) { 477 case EFI_SUCCESS: 478 if (duplicates) 479 up(&efivars_lock); 480 481 variable_name_size = var_name_strnsize(variable_name, 482 variable_name_size); 483 484 /* 485 * Some firmware implementations return the 486 * same variable name on multiple calls to 487 * get_next_variable(). Terminate the loop 488 * immediately as there is no guarantee that 489 * we'll ever see a different variable name, 490 * and may end up looping here forever. 491 */ 492 if (duplicates && 493 variable_is_present(variable_name, &vendor_guid, 494 head)) { 495 dup_variable_bug(variable_name, &vendor_guid, 496 variable_name_size); 497 status = EFI_NOT_FOUND; 498 } else { 499 err = func(variable_name, vendor_guid, 500 variable_name_size, data); 501 if (err) 502 status = EFI_NOT_FOUND; 503 } 504 505 if (duplicates) { 506 if (down_interruptible(&efivars_lock)) { 507 err = -EINTR; 508 goto free; 509 } 510 } 511 512 break; 513 case EFI_NOT_FOUND: 514 break; 515 default: 516 printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n", 517 status); 518 status = EFI_NOT_FOUND; 519 break; 520 } 521 522 } while (status != EFI_NOT_FOUND); 523 524 up(&efivars_lock); 525 free: 526 kfree(variable_name); 527 528 return err; 529 } 530 EXPORT_SYMBOL_GPL(efivar_init); 531 532 /** 533 * efivar_entry_add - add entry to variable list 534 * @entry: entry to add to list 535 * @head: list head 536 * 537 * Returns 0 on success, or a kernel error code on failure. 538 */ 539 int efivar_entry_add(struct efivar_entry *entry, struct list_head *head) 540 { 541 if (down_interruptible(&efivars_lock)) 542 return -EINTR; 543 list_add(&entry->list, head); 544 up(&efivars_lock); 545 546 return 0; 547 } 548 EXPORT_SYMBOL_GPL(efivar_entry_add); 549 550 /** 551 * efivar_entry_remove - remove entry from variable list 552 * @entry: entry to remove from list 553 * 554 * Returns 0 on success, or a kernel error code on failure. 555 */ 556 int efivar_entry_remove(struct efivar_entry *entry) 557 { 558 if (down_interruptible(&efivars_lock)) 559 return -EINTR; 560 list_del(&entry->list); 561 up(&efivars_lock); 562 563 return 0; 564 } 565 EXPORT_SYMBOL_GPL(efivar_entry_remove); 566 567 /* 568 * efivar_entry_list_del_unlock - remove entry from variable list 569 * @entry: entry to remove 570 * 571 * Remove @entry from the variable list and release the list lock. 572 * 573 * NOTE: slightly weird locking semantics here - we expect to be 574 * called with the efivars lock already held, and we release it before 575 * returning. This is because this function is usually called after 576 * set_variable() while the lock is still held. 577 */ 578 static void efivar_entry_list_del_unlock(struct efivar_entry *entry) 579 { 580 list_del(&entry->list); 581 up(&efivars_lock); 582 } 583 584 /** 585 * __efivar_entry_delete - delete an EFI variable 586 * @entry: entry containing EFI variable to delete 587 * 588 * Delete the variable from the firmware but leave @entry on the 589 * variable list. 590 * 591 * This function differs from efivar_entry_delete() because it does 592 * not remove @entry from the variable list. Also, it is safe to be 593 * called from within a efivar_entry_iter_begin() and 594 * efivar_entry_iter_end() region, unlike efivar_entry_delete(). 595 * 596 * Returns 0 on success, or a converted EFI status code if 597 * set_variable() fails. 598 */ 599 int __efivar_entry_delete(struct efivar_entry *entry) 600 { 601 efi_status_t status; 602 603 if (!__efivars) 604 return -EINVAL; 605 606 status = __efivars->ops->set_variable(entry->var.VariableName, 607 &entry->var.VendorGuid, 608 0, 0, NULL); 609 610 return efi_status_to_err(status); 611 } 612 EXPORT_SYMBOL_GPL(__efivar_entry_delete); 613 614 /** 615 * efivar_entry_delete - delete variable and remove entry from list 616 * @entry: entry containing variable to delete 617 * 618 * Delete the variable from the firmware and remove @entry from the 619 * variable list. It is the caller's responsibility to free @entry 620 * once we return. 621 * 622 * Returns 0 on success, -EINTR if we can't grab the semaphore, 623 * converted EFI status code if set_variable() fails. 624 */ 625 int efivar_entry_delete(struct efivar_entry *entry) 626 { 627 const struct efivar_operations *ops; 628 efi_status_t status; 629 630 if (down_interruptible(&efivars_lock)) 631 return -EINTR; 632 633 if (!__efivars) { 634 up(&efivars_lock); 635 return -EINVAL; 636 } 637 ops = __efivars->ops; 638 status = ops->set_variable(entry->var.VariableName, 639 &entry->var.VendorGuid, 640 0, 0, NULL); 641 if (!(status == EFI_SUCCESS || status == EFI_NOT_FOUND)) { 642 up(&efivars_lock); 643 return efi_status_to_err(status); 644 } 645 646 efivar_entry_list_del_unlock(entry); 647 return 0; 648 } 649 EXPORT_SYMBOL_GPL(efivar_entry_delete); 650 651 /** 652 * efivar_entry_set - call set_variable() 653 * @entry: entry containing the EFI variable to write 654 * @attributes: variable attributes 655 * @size: size of @data buffer 656 * @data: buffer containing variable data 657 * @head: head of variable list 658 * 659 * Calls set_variable() for an EFI variable. If creating a new EFI 660 * variable, this function is usually followed by efivar_entry_add(). 661 * 662 * Before writing the variable, the remaining EFI variable storage 663 * space is checked to ensure there is enough room available. 664 * 665 * If @head is not NULL a lookup is performed to determine whether 666 * the entry is already on the list. 667 * 668 * Returns 0 on success, -EINTR if we can't grab the semaphore, 669 * -EEXIST if a lookup is performed and the entry already exists on 670 * the list, or a converted EFI status code if set_variable() fails. 671 */ 672 int efivar_entry_set(struct efivar_entry *entry, u32 attributes, 673 unsigned long size, void *data, struct list_head *head) 674 { 675 const struct efivar_operations *ops; 676 efi_status_t status; 677 efi_char16_t *name = entry->var.VariableName; 678 efi_guid_t vendor = entry->var.VendorGuid; 679 680 if (down_interruptible(&efivars_lock)) 681 return -EINTR; 682 683 if (!__efivars) { 684 up(&efivars_lock); 685 return -EINVAL; 686 } 687 ops = __efivars->ops; 688 if (head && efivar_entry_find(name, vendor, head, false)) { 689 up(&efivars_lock); 690 return -EEXIST; 691 } 692 693 status = check_var_size(attributes, size + ucs2_strsize(name, 1024)); 694 if (status == EFI_SUCCESS || status == EFI_UNSUPPORTED) 695 status = ops->set_variable(name, &vendor, 696 attributes, size, data); 697 698 up(&efivars_lock); 699 700 return efi_status_to_err(status); 701 702 } 703 EXPORT_SYMBOL_GPL(efivar_entry_set); 704 705 /* 706 * efivar_entry_set_nonblocking - call set_variable_nonblocking() 707 * 708 * This function is guaranteed to not block and is suitable for calling 709 * from crash/panic handlers. 710 * 711 * Crucially, this function will not block if it cannot acquire 712 * efivars_lock. Instead, it returns -EBUSY. 713 */ 714 static int 715 efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor, 716 u32 attributes, unsigned long size, void *data) 717 { 718 const struct efivar_operations *ops; 719 efi_status_t status; 720 721 if (down_trylock(&efivars_lock)) 722 return -EBUSY; 723 724 if (!__efivars) { 725 up(&efivars_lock); 726 return -EINVAL; 727 } 728 729 status = check_var_size_nonblocking(attributes, 730 size + ucs2_strsize(name, 1024)); 731 if (status != EFI_SUCCESS) { 732 up(&efivars_lock); 733 return -ENOSPC; 734 } 735 736 ops = __efivars->ops; 737 status = ops->set_variable_nonblocking(name, &vendor, attributes, 738 size, data); 739 740 up(&efivars_lock); 741 return efi_status_to_err(status); 742 } 743 744 /** 745 * efivar_entry_set_safe - call set_variable() if enough space in firmware 746 * @name: buffer containing the variable name 747 * @vendor: variable vendor guid 748 * @attributes: variable attributes 749 * @block: can we block in this context? 750 * @size: size of @data buffer 751 * @data: buffer containing variable data 752 * 753 * Ensures there is enough free storage in the firmware for this variable, and 754 * if so, calls set_variable(). If creating a new EFI variable, this function 755 * is usually followed by efivar_entry_add(). 756 * 757 * Returns 0 on success, -ENOSPC if the firmware does not have enough 758 * space for set_variable() to succeed, or a converted EFI status code 759 * if set_variable() fails. 760 */ 761 int efivar_entry_set_safe(efi_char16_t *name, efi_guid_t vendor, u32 attributes, 762 bool block, unsigned long size, void *data) 763 { 764 const struct efivar_operations *ops; 765 efi_status_t status; 766 767 if (!__efivars) 768 return -EINVAL; 769 770 ops = __efivars->ops; 771 if (!ops->query_variable_store) 772 return -ENOSYS; 773 774 /* 775 * If the EFI variable backend provides a non-blocking 776 * ->set_variable() operation and we're in a context where we 777 * cannot block, then we need to use it to avoid live-locks, 778 * since the implication is that the regular ->set_variable() 779 * will block. 780 * 781 * If no ->set_variable_nonblocking() is provided then 782 * ->set_variable() is assumed to be non-blocking. 783 */ 784 if (!block && ops->set_variable_nonblocking) 785 return efivar_entry_set_nonblocking(name, vendor, attributes, 786 size, data); 787 788 if (!block) { 789 if (down_trylock(&efivars_lock)) 790 return -EBUSY; 791 } else { 792 if (down_interruptible(&efivars_lock)) 793 return -EINTR; 794 } 795 796 status = check_var_size(attributes, size + ucs2_strsize(name, 1024)); 797 if (status != EFI_SUCCESS) { 798 up(&efivars_lock); 799 return -ENOSPC; 800 } 801 802 status = ops->set_variable(name, &vendor, attributes, size, data); 803 804 up(&efivars_lock); 805 806 return efi_status_to_err(status); 807 } 808 EXPORT_SYMBOL_GPL(efivar_entry_set_safe); 809 810 /** 811 * efivar_entry_find - search for an entry 812 * @name: the EFI variable name 813 * @guid: the EFI variable vendor's guid 814 * @head: head of the variable list 815 * @remove: should we remove the entry from the list? 816 * 817 * Search for an entry on the variable list that has the EFI variable 818 * name @name and vendor guid @guid. If an entry is found on the list 819 * and @remove is true, the entry is removed from the list. 820 * 821 * The caller MUST call efivar_entry_iter_begin() and 822 * efivar_entry_iter_end() before and after the invocation of this 823 * function, respectively. 824 * 825 * Returns the entry if found on the list, %NULL otherwise. 826 */ 827 struct efivar_entry *efivar_entry_find(efi_char16_t *name, efi_guid_t guid, 828 struct list_head *head, bool remove) 829 { 830 struct efivar_entry *entry, *n; 831 int strsize1, strsize2; 832 bool found = false; 833 834 list_for_each_entry_safe(entry, n, head, list) { 835 strsize1 = ucs2_strsize(name, 1024); 836 strsize2 = ucs2_strsize(entry->var.VariableName, 1024); 837 if (strsize1 == strsize2 && 838 !memcmp(name, &(entry->var.VariableName), strsize1) && 839 !efi_guidcmp(guid, entry->var.VendorGuid)) { 840 found = true; 841 break; 842 } 843 } 844 845 if (!found) 846 return NULL; 847 848 if (remove) { 849 if (entry->scanning) { 850 /* 851 * The entry will be deleted 852 * after scanning is completed. 853 */ 854 entry->deleting = true; 855 } else 856 list_del(&entry->list); 857 } 858 859 return entry; 860 } 861 EXPORT_SYMBOL_GPL(efivar_entry_find); 862 863 /** 864 * efivar_entry_size - obtain the size of a variable 865 * @entry: entry for this variable 866 * @size: location to store the variable's size 867 */ 868 int efivar_entry_size(struct efivar_entry *entry, unsigned long *size) 869 { 870 const struct efivar_operations *ops; 871 efi_status_t status; 872 873 *size = 0; 874 875 if (down_interruptible(&efivars_lock)) 876 return -EINTR; 877 if (!__efivars) { 878 up(&efivars_lock); 879 return -EINVAL; 880 } 881 ops = __efivars->ops; 882 status = ops->get_variable(entry->var.VariableName, 883 &entry->var.VendorGuid, NULL, size, NULL); 884 up(&efivars_lock); 885 886 if (status != EFI_BUFFER_TOO_SMALL) 887 return efi_status_to_err(status); 888 889 return 0; 890 } 891 EXPORT_SYMBOL_GPL(efivar_entry_size); 892 893 /** 894 * __efivar_entry_get - call get_variable() 895 * @entry: read data for this variable 896 * @attributes: variable attributes 897 * @size: size of @data buffer 898 * @data: buffer to store variable data 899 * 900 * The caller MUST call efivar_entry_iter_begin() and 901 * efivar_entry_iter_end() before and after the invocation of this 902 * function, respectively. 903 */ 904 int __efivar_entry_get(struct efivar_entry *entry, u32 *attributes, 905 unsigned long *size, void *data) 906 { 907 efi_status_t status; 908 909 if (!__efivars) 910 return -EINVAL; 911 912 status = __efivars->ops->get_variable(entry->var.VariableName, 913 &entry->var.VendorGuid, 914 attributes, size, data); 915 916 return efi_status_to_err(status); 917 } 918 EXPORT_SYMBOL_GPL(__efivar_entry_get); 919 920 /** 921 * efivar_entry_get - call get_variable() 922 * @entry: read data for this variable 923 * @attributes: variable attributes 924 * @size: size of @data buffer 925 * @data: buffer to store variable data 926 */ 927 int efivar_entry_get(struct efivar_entry *entry, u32 *attributes, 928 unsigned long *size, void *data) 929 { 930 efi_status_t status; 931 932 if (down_interruptible(&efivars_lock)) 933 return -EINTR; 934 935 if (!__efivars) { 936 up(&efivars_lock); 937 return -EINVAL; 938 } 939 940 status = __efivars->ops->get_variable(entry->var.VariableName, 941 &entry->var.VendorGuid, 942 attributes, size, data); 943 up(&efivars_lock); 944 945 return efi_status_to_err(status); 946 } 947 EXPORT_SYMBOL_GPL(efivar_entry_get); 948 949 /** 950 * efivar_entry_set_get_size - call set_variable() and get new size (atomic) 951 * @entry: entry containing variable to set and get 952 * @attributes: attributes of variable to be written 953 * @size: size of data buffer 954 * @data: buffer containing data to write 955 * @set: did the set_variable() call succeed? 956 * 957 * This is a pretty special (complex) function. See efivarfs_file_write(). 958 * 959 * Atomically call set_variable() for @entry and if the call is 960 * successful, return the new size of the variable from get_variable() 961 * in @size. The success of set_variable() is indicated by @set. 962 * 963 * Returns 0 on success, -EINVAL if the variable data is invalid, 964 * -ENOSPC if the firmware does not have enough available space, or a 965 * converted EFI status code if either of set_variable() or 966 * get_variable() fail. 967 * 968 * If the EFI variable does not exist when calling set_variable() 969 * (EFI_NOT_FOUND), @entry is removed from the variable list. 970 */ 971 int efivar_entry_set_get_size(struct efivar_entry *entry, u32 attributes, 972 unsigned long *size, void *data, bool *set) 973 { 974 const struct efivar_operations *ops; 975 efi_char16_t *name = entry->var.VariableName; 976 efi_guid_t *vendor = &entry->var.VendorGuid; 977 efi_status_t status; 978 int err; 979 980 *set = false; 981 982 if (efivar_validate(*vendor, name, data, *size) == false) 983 return -EINVAL; 984 985 /* 986 * The lock here protects the get_variable call, the conditional 987 * set_variable call, and removal of the variable from the efivars 988 * list (in the case of an authenticated delete). 989 */ 990 if (down_interruptible(&efivars_lock)) 991 return -EINTR; 992 993 if (!__efivars) { 994 err = -EINVAL; 995 goto out; 996 } 997 998 /* 999 * Ensure that the available space hasn't shrunk below the safe level 1000 */ 1001 status = check_var_size(attributes, *size + ucs2_strsize(name, 1024)); 1002 if (status != EFI_SUCCESS) { 1003 if (status != EFI_UNSUPPORTED) { 1004 err = efi_status_to_err(status); 1005 goto out; 1006 } 1007 1008 if (*size > 65536) { 1009 err = -ENOSPC; 1010 goto out; 1011 } 1012 } 1013 1014 ops = __efivars->ops; 1015 1016 status = ops->set_variable(name, vendor, attributes, *size, data); 1017 if (status != EFI_SUCCESS) { 1018 err = efi_status_to_err(status); 1019 goto out; 1020 } 1021 1022 *set = true; 1023 1024 /* 1025 * Writing to the variable may have caused a change in size (which 1026 * could either be an append or an overwrite), or the variable to be 1027 * deleted. Perform a GetVariable() so we can tell what actually 1028 * happened. 1029 */ 1030 *size = 0; 1031 status = ops->get_variable(entry->var.VariableName, 1032 &entry->var.VendorGuid, 1033 NULL, size, NULL); 1034 1035 if (status == EFI_NOT_FOUND) 1036 efivar_entry_list_del_unlock(entry); 1037 else 1038 up(&efivars_lock); 1039 1040 if (status && status != EFI_BUFFER_TOO_SMALL) 1041 return efi_status_to_err(status); 1042 1043 return 0; 1044 1045 out: 1046 up(&efivars_lock); 1047 return err; 1048 1049 } 1050 EXPORT_SYMBOL_GPL(efivar_entry_set_get_size); 1051 1052 /** 1053 * efivar_entry_iter_begin - begin iterating the variable list 1054 * 1055 * Lock the variable list to prevent entry insertion and removal until 1056 * efivar_entry_iter_end() is called. This function is usually used in 1057 * conjunction with __efivar_entry_iter() or efivar_entry_iter(). 1058 */ 1059 int efivar_entry_iter_begin(void) 1060 { 1061 return down_interruptible(&efivars_lock); 1062 } 1063 EXPORT_SYMBOL_GPL(efivar_entry_iter_begin); 1064 1065 /** 1066 * efivar_entry_iter_end - finish iterating the variable list 1067 * 1068 * Unlock the variable list and allow modifications to the list again. 1069 */ 1070 void efivar_entry_iter_end(void) 1071 { 1072 up(&efivars_lock); 1073 } 1074 EXPORT_SYMBOL_GPL(efivar_entry_iter_end); 1075 1076 /** 1077 * __efivar_entry_iter - iterate over variable list 1078 * @func: callback function 1079 * @head: head of the variable list 1080 * @data: function-specific data to pass to callback 1081 * @prev: entry to begin iterating from 1082 * 1083 * Iterate over the list of EFI variables and call @func with every 1084 * entry on the list. It is safe for @func to remove entries in the 1085 * list via efivar_entry_delete(). 1086 * 1087 * You MUST call efivar_enter_iter_begin() before this function, and 1088 * efivar_entry_iter_end() afterwards. 1089 * 1090 * It is possible to begin iteration from an arbitrary entry within 1091 * the list by passing @prev. @prev is updated on return to point to 1092 * the last entry passed to @func. To begin iterating from the 1093 * beginning of the list @prev must be %NULL. 1094 * 1095 * The restrictions for @func are the same as documented for 1096 * efivar_entry_iter(). 1097 */ 1098 int __efivar_entry_iter(int (*func)(struct efivar_entry *, void *), 1099 struct list_head *head, void *data, 1100 struct efivar_entry **prev) 1101 { 1102 struct efivar_entry *entry, *n; 1103 int err = 0; 1104 1105 if (!prev || !*prev) { 1106 list_for_each_entry_safe(entry, n, head, list) { 1107 err = func(entry, data); 1108 if (err) 1109 break; 1110 } 1111 1112 if (prev) 1113 *prev = entry; 1114 1115 return err; 1116 } 1117 1118 1119 list_for_each_entry_safe_continue((*prev), n, head, list) { 1120 err = func(*prev, data); 1121 if (err) 1122 break; 1123 } 1124 1125 return err; 1126 } 1127 EXPORT_SYMBOL_GPL(__efivar_entry_iter); 1128 1129 /** 1130 * efivar_entry_iter - iterate over variable list 1131 * @func: callback function 1132 * @head: head of variable list 1133 * @data: function-specific data to pass to callback 1134 * 1135 * Iterate over the list of EFI variables and call @func with every 1136 * entry on the list. It is safe for @func to remove entries in the 1137 * list via efivar_entry_delete() while iterating. 1138 * 1139 * Some notes for the callback function: 1140 * - a non-zero return value indicates an error and terminates the loop 1141 * - @func is called from atomic context 1142 */ 1143 int efivar_entry_iter(int (*func)(struct efivar_entry *, void *), 1144 struct list_head *head, void *data) 1145 { 1146 int err = 0; 1147 1148 err = efivar_entry_iter_begin(); 1149 if (err) 1150 return err; 1151 err = __efivar_entry_iter(func, head, data, NULL); 1152 efivar_entry_iter_end(); 1153 1154 return err; 1155 } 1156 EXPORT_SYMBOL_GPL(efivar_entry_iter); 1157 1158 /** 1159 * efivars_kobject - get the kobject for the registered efivars 1160 * 1161 * If efivars_register() has not been called we return NULL, 1162 * otherwise return the kobject used at registration time. 1163 */ 1164 struct kobject *efivars_kobject(void) 1165 { 1166 if (!__efivars) 1167 return NULL; 1168 1169 return __efivars->kobject; 1170 } 1171 EXPORT_SYMBOL_GPL(efivars_kobject); 1172 1173 /** 1174 * efivar_run_worker - schedule the efivar worker thread 1175 */ 1176 void efivar_run_worker(void) 1177 { 1178 if (efivar_wq_enabled) 1179 schedule_work(&efivar_work); 1180 } 1181 EXPORT_SYMBOL_GPL(efivar_run_worker); 1182 1183 /** 1184 * efivars_register - register an efivars 1185 * @efivars: efivars to register 1186 * @ops: efivars operations 1187 * @kobject: @efivars-specific kobject 1188 * 1189 * Only a single efivars can be registered at any time. 1190 */ 1191 int efivars_register(struct efivars *efivars, 1192 const struct efivar_operations *ops, 1193 struct kobject *kobject) 1194 { 1195 if (down_interruptible(&efivars_lock)) 1196 return -EINTR; 1197 1198 efivars->ops = ops; 1199 efivars->kobject = kobject; 1200 1201 __efivars = efivars; 1202 1203 pr_info("Registered efivars operations\n"); 1204 1205 up(&efivars_lock); 1206 1207 return 0; 1208 } 1209 EXPORT_SYMBOL_GPL(efivars_register); 1210 1211 /** 1212 * efivars_unregister - unregister an efivars 1213 * @efivars: efivars to unregister 1214 * 1215 * The caller must have already removed every entry from the list, 1216 * failure to do so is an error. 1217 */ 1218 int efivars_unregister(struct efivars *efivars) 1219 { 1220 int rv; 1221 1222 if (down_interruptible(&efivars_lock)) 1223 return -EINTR; 1224 1225 if (!__efivars) { 1226 printk(KERN_ERR "efivars not registered\n"); 1227 rv = -EINVAL; 1228 goto out; 1229 } 1230 1231 if (__efivars != efivars) { 1232 rv = -EINVAL; 1233 goto out; 1234 } 1235 1236 pr_info("Unregistered efivars operations\n"); 1237 __efivars = NULL; 1238 1239 rv = 0; 1240 out: 1241 up(&efivars_lock); 1242 return rv; 1243 } 1244 EXPORT_SYMBOL_GPL(efivars_unregister); 1245