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