1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Helper functions used by the EFI stub on multiple 4 * architectures. This should be #included by the EFI stub 5 * implementation files. 6 * 7 * Copyright 2011 Intel Corporation; author Matt Fleming 8 */ 9 10 #include <linux/stdarg.h> 11 12 #include <linux/efi.h> 13 #include <linux/kernel.h> 14 #include <asm/efi.h> 15 #include <asm/setup.h> 16 17 #include "efistub.h" 18 19 bool efi_nochunk; 20 bool efi_nokaslr = !IS_ENABLED(CONFIG_RANDOMIZE_BASE); 21 bool efi_novamap; 22 23 static bool efi_noinitrd; 24 static bool efi_nosoftreserve; 25 static bool efi_disable_pci_dma = IS_ENABLED(CONFIG_EFI_DISABLE_PCI_DMA); 26 27 int efi_mem_encrypt; 28 29 bool __pure __efi_soft_reserve_enabled(void) 30 { 31 return !efi_nosoftreserve; 32 } 33 34 /** 35 * efi_parse_options() - Parse EFI command line options 36 * @cmdline: kernel command line 37 * 38 * Parse the ASCII string @cmdline for EFI options, denoted by the efi= 39 * option, e.g. efi=nochunk. 40 * 41 * It should be noted that efi= is parsed in two very different 42 * environments, first in the early boot environment of the EFI boot 43 * stub, and subsequently during the kernel boot. 44 * 45 * Return: status code 46 */ 47 efi_status_t efi_parse_options(char const *cmdline) 48 { 49 size_t len; 50 efi_status_t status; 51 char *str, *buf; 52 53 if (!cmdline) 54 return EFI_SUCCESS; 55 56 len = strnlen(cmdline, COMMAND_LINE_SIZE - 1) + 1; 57 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, len, (void **)&buf); 58 if (status != EFI_SUCCESS) 59 return status; 60 61 memcpy(buf, cmdline, len - 1); 62 buf[len - 1] = '\0'; 63 str = skip_spaces(buf); 64 65 while (*str) { 66 char *param, *val; 67 68 str = next_arg(str, ¶m, &val); 69 if (!val && !strcmp(param, "--")) 70 break; 71 72 if (!strcmp(param, "nokaslr")) { 73 efi_nokaslr = true; 74 } else if (!strcmp(param, "quiet")) { 75 efi_loglevel = CONSOLE_LOGLEVEL_QUIET; 76 } else if (!strcmp(param, "noinitrd")) { 77 efi_noinitrd = true; 78 } else if (IS_ENABLED(CONFIG_X86_64) && !strcmp(param, "no5lvl")) { 79 efi_no5lvl = true; 80 } else if (IS_ENABLED(CONFIG_ARCH_HAS_MEM_ENCRYPT) && 81 !strcmp(param, "mem_encrypt") && val) { 82 if (parse_option_str(val, "on")) 83 efi_mem_encrypt = 1; 84 else if (parse_option_str(val, "off")) 85 efi_mem_encrypt = -1; 86 } else if (!strcmp(param, "efi") && val) { 87 efi_nochunk = parse_option_str(val, "nochunk"); 88 efi_novamap |= parse_option_str(val, "novamap"); 89 90 efi_nosoftreserve = IS_ENABLED(CONFIG_EFI_SOFT_RESERVE) && 91 parse_option_str(val, "nosoftreserve"); 92 93 if (parse_option_str(val, "disable_early_pci_dma")) 94 efi_disable_pci_dma = true; 95 if (parse_option_str(val, "no_disable_early_pci_dma")) 96 efi_disable_pci_dma = false; 97 if (parse_option_str(val, "debug")) 98 efi_loglevel = CONSOLE_LOGLEVEL_DEBUG; 99 } else if (!strcmp(param, "video") && 100 val && strstarts(val, "efifb:")) { 101 efi_parse_option_graphics(val + strlen("efifb:")); 102 } 103 } 104 efi_bs_call(free_pool, buf); 105 return EFI_SUCCESS; 106 } 107 108 /* 109 * The EFI_LOAD_OPTION descriptor has the following layout: 110 * u32 Attributes; 111 * u16 FilePathListLength; 112 * u16 Description[]; 113 * efi_device_path_protocol_t FilePathList[]; 114 * u8 OptionalData[]; 115 * 116 * This function validates and unpacks the variable-size data fields. 117 */ 118 static 119 bool efi_load_option_unpack(efi_load_option_unpacked_t *dest, 120 const efi_load_option_t *src, size_t size) 121 { 122 const void *pos; 123 u16 c; 124 efi_device_path_protocol_t header; 125 const efi_char16_t *description; 126 const efi_device_path_protocol_t *file_path_list; 127 128 if (size < offsetof(efi_load_option_t, variable_data)) 129 return false; 130 pos = src->variable_data; 131 size -= offsetof(efi_load_option_t, variable_data); 132 133 if ((src->attributes & ~EFI_LOAD_OPTION_MASK) != 0) 134 return false; 135 136 /* Scan description. */ 137 description = pos; 138 do { 139 if (size < sizeof(c)) 140 return false; 141 c = *(const u16 *)pos; 142 pos += sizeof(c); 143 size -= sizeof(c); 144 } while (c != L'\0'); 145 146 /* Scan file_path_list. */ 147 file_path_list = pos; 148 do { 149 if (size < sizeof(header)) 150 return false; 151 header = *(const efi_device_path_protocol_t *)pos; 152 if (header.length < sizeof(header)) 153 return false; 154 if (size < header.length) 155 return false; 156 pos += header.length; 157 size -= header.length; 158 } while ((header.type != EFI_DEV_END_PATH && header.type != EFI_DEV_END_PATH2) || 159 (header.sub_type != EFI_DEV_END_ENTIRE)); 160 if (pos != (const void *)file_path_list + src->file_path_list_length) 161 return false; 162 163 dest->attributes = src->attributes; 164 dest->file_path_list_length = src->file_path_list_length; 165 dest->description = description; 166 dest->file_path_list = file_path_list; 167 dest->optional_data_size = size; 168 dest->optional_data = size ? pos : NULL; 169 170 return true; 171 } 172 173 /* 174 * At least some versions of Dell firmware pass the entire contents of the 175 * Boot#### variable, i.e. the EFI_LOAD_OPTION descriptor, rather than just the 176 * OptionalData field. 177 * 178 * Detect this case and extract OptionalData. 179 */ 180 void efi_apply_loadoptions_quirk(const void **load_options, u32 *load_options_size) 181 { 182 const efi_load_option_t *load_option = *load_options; 183 efi_load_option_unpacked_t load_option_unpacked; 184 185 if (!IS_ENABLED(CONFIG_X86)) 186 return; 187 if (!load_option) 188 return; 189 if (*load_options_size < sizeof(*load_option)) 190 return; 191 if ((load_option->attributes & ~EFI_LOAD_OPTION_BOOT_MASK) != 0) 192 return; 193 194 if (!efi_load_option_unpack(&load_option_unpacked, load_option, *load_options_size)) 195 return; 196 197 efi_warn_once(FW_BUG "LoadOptions is an EFI_LOAD_OPTION descriptor\n"); 198 efi_warn_once(FW_BUG "Using OptionalData as a workaround\n"); 199 200 *load_options = load_option_unpacked.optional_data; 201 *load_options_size = load_option_unpacked.optional_data_size; 202 } 203 204 enum efistub_event { 205 EFISTUB_EVT_INITRD, 206 EFISTUB_EVT_LOAD_OPTIONS, 207 EFISTUB_EVT_COUNT, 208 }; 209 210 #define STR_WITH_SIZE(s) sizeof(s), s 211 212 static const struct { 213 u32 pcr_index; 214 u32 event_id; 215 u32 event_data_len; 216 u8 event_data[52]; 217 } events[] = { 218 [EFISTUB_EVT_INITRD] = { 219 9, 220 INITRD_EVENT_TAG_ID, 221 STR_WITH_SIZE("Linux initrd") 222 }, 223 [EFISTUB_EVT_LOAD_OPTIONS] = { 224 9, 225 LOAD_OPTIONS_EVENT_TAG_ID, 226 STR_WITH_SIZE("LOADED_IMAGE::LoadOptions") 227 }, 228 }; 229 230 static efi_status_t efi_measure_tagged_event(unsigned long load_addr, 231 unsigned long load_size, 232 enum efistub_event event) 233 { 234 efi_guid_t tcg2_guid = EFI_TCG2_PROTOCOL_GUID; 235 efi_tcg2_protocol_t *tcg2 = NULL; 236 efi_status_t status; 237 238 efi_bs_call(locate_protocol, &tcg2_guid, NULL, (void **)&tcg2); 239 if (tcg2) { 240 struct efi_measured_event { 241 efi_tcg2_event_t event_data; 242 efi_tcg2_tagged_event_t tagged_event; 243 u8 tagged_event_data[]; 244 } *evt; 245 int size = sizeof(*evt) + events[event].event_data_len; 246 247 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, size, 248 (void **)&evt); 249 if (status != EFI_SUCCESS) 250 goto fail; 251 252 evt->event_data = (struct efi_tcg2_event){ 253 .event_size = size, 254 .event_header.header_size = sizeof(evt->event_data.event_header), 255 .event_header.header_version = EFI_TCG2_EVENT_HEADER_VERSION, 256 .event_header.pcr_index = events[event].pcr_index, 257 .event_header.event_type = EV_EVENT_TAG, 258 }; 259 260 evt->tagged_event = (struct efi_tcg2_tagged_event){ 261 .tagged_event_id = events[event].event_id, 262 .tagged_event_data_size = events[event].event_data_len, 263 }; 264 265 memcpy(evt->tagged_event_data, events[event].event_data, 266 events[event].event_data_len); 267 268 status = efi_call_proto(tcg2, hash_log_extend_event, 0, 269 load_addr, load_size, &evt->event_data); 270 efi_bs_call(free_pool, evt); 271 272 if (status != EFI_SUCCESS) 273 goto fail; 274 return EFI_SUCCESS; 275 } 276 277 return EFI_UNSUPPORTED; 278 fail: 279 efi_warn("Failed to measure data for event %d: 0x%lx\n", event, status); 280 return status; 281 } 282 283 /* 284 * Convert the unicode UEFI command line to ASCII to pass to kernel. 285 * Size of memory allocated return in *cmd_line_len. 286 * Returns NULL on error. 287 */ 288 char *efi_convert_cmdline(efi_loaded_image_t *image, int *cmd_line_len) 289 { 290 const efi_char16_t *options = efi_table_attr(image, load_options); 291 u32 options_size = efi_table_attr(image, load_options_size); 292 int options_bytes = 0, safe_options_bytes = 0; /* UTF-8 bytes */ 293 unsigned long cmdline_addr = 0; 294 const efi_char16_t *s2; 295 bool in_quote = false; 296 efi_status_t status; 297 u32 options_chars; 298 299 if (options_size > 0) 300 efi_measure_tagged_event((unsigned long)options, options_size, 301 EFISTUB_EVT_LOAD_OPTIONS); 302 303 efi_apply_loadoptions_quirk((const void **)&options, &options_size); 304 options_chars = options_size / sizeof(efi_char16_t); 305 306 if (options) { 307 s2 = options; 308 while (options_bytes < COMMAND_LINE_SIZE && options_chars--) { 309 efi_char16_t c = *s2++; 310 311 if (c < 0x80) { 312 if (c == L'\0' || c == L'\n') 313 break; 314 if (c == L'"') 315 in_quote = !in_quote; 316 else if (!in_quote && isspace((char)c)) 317 safe_options_bytes = options_bytes; 318 319 options_bytes++; 320 continue; 321 } 322 323 /* 324 * Get the number of UTF-8 bytes corresponding to a 325 * UTF-16 character. 326 * The first part handles everything in the BMP. 327 */ 328 options_bytes += 2 + (c >= 0x800); 329 /* 330 * Add one more byte for valid surrogate pairs. Invalid 331 * surrogates will be replaced with 0xfffd and take up 332 * only 3 bytes. 333 */ 334 if ((c & 0xfc00) == 0xd800) { 335 /* 336 * If the very last word is a high surrogate, 337 * we must ignore it since we can't access the 338 * low surrogate. 339 */ 340 if (!options_chars) { 341 options_bytes -= 3; 342 } else if ((*s2 & 0xfc00) == 0xdc00) { 343 options_bytes++; 344 options_chars--; 345 s2++; 346 } 347 } 348 } 349 if (options_bytes >= COMMAND_LINE_SIZE) { 350 options_bytes = safe_options_bytes; 351 efi_err("Command line is too long: truncated to %d bytes\n", 352 options_bytes); 353 } 354 } 355 356 options_bytes++; /* NUL termination */ 357 358 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, options_bytes, 359 (void **)&cmdline_addr); 360 if (status != EFI_SUCCESS) 361 return NULL; 362 363 snprintf((char *)cmdline_addr, options_bytes, "%.*ls", 364 options_bytes - 1, options); 365 366 *cmd_line_len = options_bytes; 367 return (char *)cmdline_addr; 368 } 369 370 /** 371 * efi_exit_boot_services() - Exit boot services 372 * @handle: handle of the exiting image 373 * @priv: argument to be passed to @priv_func 374 * @priv_func: function to process the memory map before exiting boot services 375 * 376 * Handle calling ExitBootServices according to the requirements set out by the 377 * spec. Obtains the current memory map, and returns that info after calling 378 * ExitBootServices. The client must specify a function to perform any 379 * processing of the memory map data prior to ExitBootServices. A client 380 * specific structure may be passed to the function via priv. The client 381 * function may be called multiple times. 382 * 383 * Return: status code 384 */ 385 efi_status_t efi_exit_boot_services(void *handle, void *priv, 386 efi_exit_boot_map_processing priv_func) 387 { 388 struct efi_boot_memmap *map; 389 efi_status_t status; 390 391 if (efi_disable_pci_dma) 392 efi_pci_disable_bridge_busmaster(); 393 394 status = efi_get_memory_map(&map, true); 395 if (status != EFI_SUCCESS) 396 return status; 397 398 status = priv_func(map, priv); 399 if (status != EFI_SUCCESS) { 400 efi_bs_call(free_pool, map); 401 return status; 402 } 403 404 status = efi_bs_call(exit_boot_services, handle, map->map_key); 405 406 if (status == EFI_INVALID_PARAMETER) { 407 /* 408 * The memory map changed between efi_get_memory_map() and 409 * exit_boot_services(). Per the UEFI Spec v2.6, Section 6.4: 410 * EFI_BOOT_SERVICES.ExitBootServices we need to get the 411 * updated map, and try again. The spec implies one retry 412 * should be sufficent, which is confirmed against the EDK2 413 * implementation. Per the spec, we can only invoke 414 * get_memory_map() and exit_boot_services() - we cannot alloc 415 * so efi_get_memory_map() cannot be used, and we must reuse 416 * the buffer. For all practical purposes, the headroom in the 417 * buffer should account for any changes in the map so the call 418 * to get_memory_map() is expected to succeed here. 419 */ 420 map->map_size = map->buff_size; 421 status = efi_bs_call(get_memory_map, 422 &map->map_size, 423 &map->map, 424 &map->map_key, 425 &map->desc_size, 426 &map->desc_ver); 427 428 /* exit_boot_services() was called, thus cannot free */ 429 if (status != EFI_SUCCESS) 430 return status; 431 432 status = priv_func(map, priv); 433 /* exit_boot_services() was called, thus cannot free */ 434 if (status != EFI_SUCCESS) 435 return status; 436 437 status = efi_bs_call(exit_boot_services, handle, map->map_key); 438 } 439 440 return status; 441 } 442 443 /** 444 * get_efi_config_table() - retrieve UEFI configuration table 445 * @guid: GUID of the configuration table to be retrieved 446 * Return: pointer to the configuration table or NULL 447 */ 448 void *get_efi_config_table(efi_guid_t guid) 449 { 450 unsigned long tables = efi_table_attr(efi_system_table, tables); 451 int nr_tables = efi_table_attr(efi_system_table, nr_tables); 452 int i; 453 454 for (i = 0; i < nr_tables; i++) { 455 efi_config_table_t *t = (void *)tables; 456 457 if (efi_guidcmp(t->guid, guid) == 0) 458 return efi_table_attr(t, table); 459 460 tables += efi_is_native() ? sizeof(efi_config_table_t) 461 : sizeof(efi_config_table_32_t); 462 } 463 return NULL; 464 } 465 466 /* 467 * The LINUX_EFI_INITRD_MEDIA_GUID vendor media device path below provides a way 468 * for the firmware or bootloader to expose the initrd data directly to the stub 469 * via the trivial LoadFile2 protocol, which is defined in the UEFI spec, and is 470 * very easy to implement. It is a simple Linux initrd specific conduit between 471 * kernel and firmware, allowing us to put the EFI stub (being part of the 472 * kernel) in charge of where and when to load the initrd, while leaving it up 473 * to the firmware to decide whether it needs to expose its filesystem hierarchy 474 * via EFI protocols. 475 */ 476 static const struct { 477 struct efi_vendor_dev_path vendor; 478 struct efi_generic_dev_path end; 479 } __packed initrd_dev_path = { 480 { 481 { 482 EFI_DEV_MEDIA, 483 EFI_DEV_MEDIA_VENDOR, 484 sizeof(struct efi_vendor_dev_path), 485 }, 486 LINUX_EFI_INITRD_MEDIA_GUID 487 }, { 488 EFI_DEV_END_PATH, 489 EFI_DEV_END_ENTIRE, 490 sizeof(struct efi_generic_dev_path) 491 } 492 }; 493 494 /** 495 * efi_load_initrd_dev_path() - load the initrd from the Linux initrd device path 496 * @initrd: pointer of struct to store the address where the initrd was loaded 497 * and the size of the loaded initrd 498 * @max: upper limit for the initrd memory allocation 499 * 500 * Return: 501 * * %EFI_SUCCESS if the initrd was loaded successfully, in which 502 * case @load_addr and @load_size are assigned accordingly 503 * * %EFI_NOT_FOUND if no LoadFile2 protocol exists on the initrd device path 504 * * %EFI_OUT_OF_RESOURCES if memory allocation failed 505 * * %EFI_LOAD_ERROR in all other cases 506 */ 507 static 508 efi_status_t efi_load_initrd_dev_path(struct linux_efi_initrd *initrd, 509 unsigned long max) 510 { 511 efi_guid_t lf2_proto_guid = EFI_LOAD_FILE2_PROTOCOL_GUID; 512 efi_device_path_protocol_t *dp; 513 efi_load_file2_protocol_t *lf2; 514 efi_handle_t handle; 515 efi_status_t status; 516 517 dp = (efi_device_path_protocol_t *)&initrd_dev_path; 518 status = efi_bs_call(locate_device_path, &lf2_proto_guid, &dp, &handle); 519 if (status != EFI_SUCCESS) 520 return status; 521 522 status = efi_bs_call(handle_protocol, handle, &lf2_proto_guid, 523 (void **)&lf2); 524 if (status != EFI_SUCCESS) 525 return status; 526 527 initrd->size = 0; 528 status = efi_call_proto(lf2, load_file, dp, false, &initrd->size, NULL); 529 if (status != EFI_BUFFER_TOO_SMALL) 530 return EFI_LOAD_ERROR; 531 532 status = efi_allocate_pages(initrd->size, &initrd->base, max); 533 if (status != EFI_SUCCESS) 534 return status; 535 536 status = efi_call_proto(lf2, load_file, dp, false, &initrd->size, 537 (void *)initrd->base); 538 if (status != EFI_SUCCESS) { 539 efi_free(initrd->size, initrd->base); 540 return EFI_LOAD_ERROR; 541 } 542 return EFI_SUCCESS; 543 } 544 545 static 546 efi_status_t efi_load_initrd_cmdline(efi_loaded_image_t *image, 547 struct linux_efi_initrd *initrd, 548 unsigned long soft_limit, 549 unsigned long hard_limit) 550 { 551 if (image == NULL) 552 return EFI_UNSUPPORTED; 553 554 return handle_cmdline_files(image, L"initrd=", sizeof(L"initrd=") - 2, 555 soft_limit, hard_limit, 556 &initrd->base, &initrd->size); 557 } 558 559 /** 560 * efi_load_initrd() - Load initial RAM disk 561 * @image: EFI loaded image protocol 562 * @soft_limit: preferred address for loading the initrd 563 * @hard_limit: upper limit address for loading the initrd 564 * 565 * Return: status code 566 */ 567 efi_status_t efi_load_initrd(efi_loaded_image_t *image, 568 unsigned long soft_limit, 569 unsigned long hard_limit, 570 const struct linux_efi_initrd **out) 571 { 572 efi_guid_t tbl_guid = LINUX_EFI_INITRD_MEDIA_GUID; 573 efi_status_t status = EFI_SUCCESS; 574 struct linux_efi_initrd initrd, *tbl; 575 576 if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD) || efi_noinitrd) 577 return EFI_SUCCESS; 578 579 status = efi_load_initrd_dev_path(&initrd, hard_limit); 580 if (status == EFI_SUCCESS) { 581 efi_info("Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path\n"); 582 if (initrd.size > 0 && 583 efi_measure_tagged_event(initrd.base, initrd.size, 584 EFISTUB_EVT_INITRD) == EFI_SUCCESS) 585 efi_info("Measured initrd data into PCR 9\n"); 586 } else if (status == EFI_NOT_FOUND) { 587 status = efi_load_initrd_cmdline(image, &initrd, soft_limit, 588 hard_limit); 589 /* command line loader disabled or no initrd= passed? */ 590 if (status == EFI_UNSUPPORTED || status == EFI_NOT_READY) 591 return EFI_SUCCESS; 592 if (status == EFI_SUCCESS) 593 efi_info("Loaded initrd from command line option\n"); 594 } 595 if (status != EFI_SUCCESS) 596 goto failed; 597 598 status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(initrd), 599 (void **)&tbl); 600 if (status != EFI_SUCCESS) 601 goto free_initrd; 602 603 *tbl = initrd; 604 status = efi_bs_call(install_configuration_table, &tbl_guid, tbl); 605 if (status != EFI_SUCCESS) 606 goto free_tbl; 607 608 if (out) 609 *out = tbl; 610 return EFI_SUCCESS; 611 612 free_tbl: 613 efi_bs_call(free_pool, tbl); 614 free_initrd: 615 efi_free(initrd.size, initrd.base); 616 failed: 617 efi_err("Failed to load initrd: 0x%lx\n", status); 618 return status; 619 } 620 621 /** 622 * efi_wait_for_key() - Wait for key stroke 623 * @usec: number of microseconds to wait for key stroke 624 * @key: key entered 625 * 626 * Wait for up to @usec microseconds for a key stroke. 627 * 628 * Return: status code, EFI_SUCCESS if key received 629 */ 630 efi_status_t efi_wait_for_key(unsigned long usec, efi_input_key_t *key) 631 { 632 efi_event_t events[2], timer; 633 unsigned long index; 634 efi_simple_text_input_protocol_t *con_in; 635 efi_status_t status; 636 637 con_in = efi_table_attr(efi_system_table, con_in); 638 if (!con_in) 639 return EFI_UNSUPPORTED; 640 efi_set_event_at(events, 0, efi_table_attr(con_in, wait_for_key)); 641 642 status = efi_bs_call(create_event, EFI_EVT_TIMER, 0, NULL, NULL, &timer); 643 if (status != EFI_SUCCESS) 644 return status; 645 646 status = efi_bs_call(set_timer, timer, EfiTimerRelative, 647 EFI_100NSEC_PER_USEC * usec); 648 if (status != EFI_SUCCESS) 649 return status; 650 efi_set_event_at(events, 1, timer); 651 652 status = efi_bs_call(wait_for_event, 2, events, &index); 653 if (status == EFI_SUCCESS) { 654 if (index == 0) 655 status = efi_call_proto(con_in, read_keystroke, key); 656 else 657 status = EFI_TIMEOUT; 658 } 659 660 efi_bs_call(close_event, timer); 661 662 return status; 663 } 664 665 /** 666 * efi_remap_image - Remap a loaded image with the appropriate permissions 667 * for code and data 668 * 669 * @image_base: the base of the image in memory 670 * @alloc_size: the size of the area in memory occupied by the image 671 * @code_size: the size of the leading part of the image containing code 672 * and read-only data 673 * 674 * efi_remap_image() uses the EFI memory attribute protocol to remap the code 675 * region of the loaded image read-only/executable, and the remainder 676 * read-write/non-executable. The code region is assumed to start at the base 677 * of the image, and will therefore cover the PE/COFF header as well. 678 */ 679 void efi_remap_image(unsigned long image_base, unsigned alloc_size, 680 unsigned long code_size) 681 { 682 efi_guid_t guid = EFI_MEMORY_ATTRIBUTE_PROTOCOL_GUID; 683 efi_memory_attribute_protocol_t *memattr; 684 efi_status_t status; 685 u64 attr; 686 687 /* 688 * If the firmware implements the EFI_MEMORY_ATTRIBUTE_PROTOCOL, let's 689 * invoke it to remap the text/rodata region of the decompressed image 690 * as read-only and the data/bss region as non-executable. 691 */ 692 status = efi_bs_call(locate_protocol, &guid, NULL, (void **)&memattr); 693 if (status != EFI_SUCCESS) 694 return; 695 696 // Get the current attributes for the entire region 697 status = memattr->get_memory_attributes(memattr, image_base, 698 alloc_size, &attr); 699 if (status != EFI_SUCCESS) { 700 efi_warn("Failed to retrieve memory attributes for image region: 0x%lx\n", 701 status); 702 return; 703 } 704 705 // Mark the code region as read-only 706 status = memattr->set_memory_attributes(memattr, image_base, code_size, 707 EFI_MEMORY_RO); 708 if (status != EFI_SUCCESS) { 709 efi_warn("Failed to remap code region read-only\n"); 710 return; 711 } 712 713 // If the entire region was already mapped as non-exec, clear the 714 // attribute from the code region. Otherwise, set it on the data 715 // region. 716 if (attr & EFI_MEMORY_XP) { 717 status = memattr->clear_memory_attributes(memattr, image_base, 718 code_size, 719 EFI_MEMORY_XP); 720 if (status != EFI_SUCCESS) 721 efi_warn("Failed to remap code region executable\n"); 722 } else { 723 status = memattr->set_memory_attributes(memattr, 724 image_base + code_size, 725 alloc_size - code_size, 726 EFI_MEMORY_XP); 727 if (status != EFI_SUCCESS) 728 efi_warn("Failed to remap data region non-executable\n"); 729 } 730 } 731