// SPDX-License-Identifier: GPL-2.0+ /* * EFI image loader * * based partly on wine code * * Copyright (c) 2016 Alexander Graf */ #include #include #include #include #include #include #include #include const efi_guid_t efi_global_variable_guid = EFI_GLOBAL_VARIABLE_GUID; const efi_guid_t efi_guid_device_path = EFI_DEVICE_PATH_PROTOCOL_GUID; const efi_guid_t efi_guid_loaded_image = EFI_LOADED_IMAGE_PROTOCOL_GUID; const efi_guid_t efi_guid_loaded_image_device_path = EFI_LOADED_IMAGE_DEVICE_PATH_PROTOCOL_GUID; const efi_guid_t efi_simple_file_system_protocol_guid = EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID; const efi_guid_t efi_file_info_guid = EFI_FILE_INFO_GUID; static int machines[] = { #if defined(__aarch64__) IMAGE_FILE_MACHINE_ARM64, #elif defined(__arm__) IMAGE_FILE_MACHINE_ARM, IMAGE_FILE_MACHINE_THUMB, IMAGE_FILE_MACHINE_ARMNT, #endif #if defined(__x86_64__) IMAGE_FILE_MACHINE_AMD64, #elif defined(__i386__) IMAGE_FILE_MACHINE_I386, #endif #if defined(__riscv) && (__riscv_xlen == 32) IMAGE_FILE_MACHINE_RISCV32, #endif #if defined(__riscv) && (__riscv_xlen == 64) IMAGE_FILE_MACHINE_RISCV64, #endif 0 }; /** * efi_print_image_info() - print information about a loaded image * * If the program counter is located within the image the offset to the base * address is shown. * * @obj: EFI object * @image: loaded image * @pc: program counter (use NULL to suppress offset output) * Return: status code */ static efi_status_t efi_print_image_info(struct efi_loaded_image_obj *obj, struct efi_loaded_image *image, void *pc) { printf("UEFI image"); printf(" [0x%p:0x%p]", image->image_base, image->image_base + image->image_size - 1); if (pc && pc >= image->image_base && pc < image->image_base + image->image_size) printf(" pc=0x%zx", pc - image->image_base); if (image->file_path) printf(" '%pD'", image->file_path); printf("\n"); return EFI_SUCCESS; } /** * efi_print_image_infos() - print information about all loaded images * * @pc: program counter (use NULL to suppress offset output) */ void efi_print_image_infos(void *pc) { struct efi_object *efiobj; struct efi_handler *handler; list_for_each_entry(efiobj, &efi_obj_list, link) { list_for_each_entry(handler, &efiobj->protocols, link) { if (!guidcmp(handler->guid, &efi_guid_loaded_image)) { efi_print_image_info( (struct efi_loaded_image_obj *)efiobj, handler->protocol_interface, pc); } } } } /** * efi_loader_relocate() - relocate UEFI binary * * @rel: pointer to the relocation table * @rel_size: size of the relocation table in bytes * @efi_reloc: actual load address of the image * @pref_address: preferred load address of the image * Return: status code */ static efi_status_t efi_loader_relocate(const IMAGE_BASE_RELOCATION *rel, unsigned long rel_size, void *efi_reloc, unsigned long pref_address) { unsigned long delta = (unsigned long)efi_reloc - pref_address; const IMAGE_BASE_RELOCATION *end; int i; if (delta == 0) return EFI_SUCCESS; end = (const IMAGE_BASE_RELOCATION *)((const char *)rel + rel_size); while (rel < end && rel->SizeOfBlock) { const uint16_t *relocs = (const uint16_t *)(rel + 1); i = (rel->SizeOfBlock - sizeof(*rel)) / sizeof(uint16_t); while (i--) { uint32_t offset = (uint32_t)(*relocs & 0xfff) + rel->VirtualAddress; int type = *relocs >> EFI_PAGE_SHIFT; uint64_t *x64 = efi_reloc + offset; uint32_t *x32 = efi_reloc + offset; uint16_t *x16 = efi_reloc + offset; switch (type) { case IMAGE_REL_BASED_ABSOLUTE: break; case IMAGE_REL_BASED_HIGH: *x16 += ((uint32_t)delta) >> 16; break; case IMAGE_REL_BASED_LOW: *x16 += (uint16_t)delta; break; case IMAGE_REL_BASED_HIGHLOW: *x32 += (uint32_t)delta; break; case IMAGE_REL_BASED_DIR64: *x64 += (uint64_t)delta; break; #ifdef __riscv case IMAGE_REL_BASED_RISCV_HI20: *x32 = ((*x32 & 0xfffff000) + (uint32_t)delta) | (*x32 & 0x00000fff); break; case IMAGE_REL_BASED_RISCV_LOW12I: case IMAGE_REL_BASED_RISCV_LOW12S: /* We know that we're 4k aligned */ if (delta & 0xfff) { printf("Unsupported reloc offset\n"); return EFI_LOAD_ERROR; } break; #endif default: printf("Unknown Relocation off %x type %x\n", offset, type); return EFI_LOAD_ERROR; } relocs++; } rel = (const IMAGE_BASE_RELOCATION *)relocs; } return EFI_SUCCESS; } void __weak invalidate_icache_all(void) { /* If the system doesn't support icache_all flush, cross our fingers */ } /** * efi_set_code_and_data_type() - determine the memory types to be used for code * and data. * * @loaded_image_info: image descriptor * @image_type: field Subsystem of the optional header for * Windows specific field */ static void efi_set_code_and_data_type( struct efi_loaded_image *loaded_image_info, uint16_t image_type) { switch (image_type) { case IMAGE_SUBSYSTEM_EFI_APPLICATION: loaded_image_info->image_code_type = EFI_LOADER_CODE; loaded_image_info->image_data_type = EFI_LOADER_DATA; break; case IMAGE_SUBSYSTEM_EFI_BOOT_SERVICE_DRIVER: loaded_image_info->image_code_type = EFI_BOOT_SERVICES_CODE; loaded_image_info->image_data_type = EFI_BOOT_SERVICES_DATA; break; case IMAGE_SUBSYSTEM_EFI_RUNTIME_DRIVER: case IMAGE_SUBSYSTEM_EFI_ROM: loaded_image_info->image_code_type = EFI_RUNTIME_SERVICES_CODE; loaded_image_info->image_data_type = EFI_RUNTIME_SERVICES_DATA; break; default: printf("%s: invalid image type: %u\n", __func__, image_type); /* Let's assume it is an application */ loaded_image_info->image_code_type = EFI_LOADER_CODE; loaded_image_info->image_data_type = EFI_LOADER_DATA; break; } } #ifdef CONFIG_EFI_SECURE_BOOT /** * cmp_pe_section - compare two sections * @arg1: Pointer to pointer to first section * @arg2: Pointer to pointer to second section * * Compare two sections in PE image. * * Return: -1, 0, 1 respectively if arg1 < arg2, arg1 == arg2 or * arg1 > arg2 */ static int cmp_pe_section(const void *arg1, const void *arg2) { const IMAGE_SECTION_HEADER *section1, *section2; section1 = *((const IMAGE_SECTION_HEADER **)arg1); section2 = *((const IMAGE_SECTION_HEADER **)arg2); if (section1->VirtualAddress < section2->VirtualAddress) return -1; else if (section1->VirtualAddress == section2->VirtualAddress) return 0; else return 1; } /** * efi_image_parse - parse a PE image * @efi: Pointer to image * @len: Size of @efi * @regp: Pointer to a list of regions * @auth: Pointer to a pointer to authentication data in PE * @auth_len: Size of @auth * * Parse image binary in PE32(+) format, assuming that sanity of PE image * has been checked by a caller. * On success, an address of authentication data in @efi and its size will * be returned in @auth and @auth_len, respectively. * * Return: true on success, false on error */ bool efi_image_parse(void *efi, size_t len, struct efi_image_regions **regp, WIN_CERTIFICATE **auth, size_t *auth_len) { struct efi_image_regions *regs; IMAGE_DOS_HEADER *dos; IMAGE_NT_HEADERS32 *nt; IMAGE_SECTION_HEADER *sections, **sorted; int num_regions, num_sections, i; int ctidx = IMAGE_DIRECTORY_ENTRY_SECURITY; u32 align, size, authsz, authoff; size_t bytes_hashed; dos = (void *)efi; nt = (void *)(efi + dos->e_lfanew); /* * Count maximum number of regions to be digested. * We don't have to have an exact number here. * See efi_image_region_add()'s in parsing below. */ num_regions = 3; /* for header */ num_regions += nt->FileHeader.NumberOfSections; num_regions++; /* for extra */ regs = calloc(sizeof(*regs) + sizeof(struct image_region) * num_regions, 1); if (!regs) goto err; regs->max = num_regions; /* * Collect data regions for hash calculation * 1. File headers */ if (nt->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR64_MAGIC) { IMAGE_NT_HEADERS64 *nt64 = (void *)nt; IMAGE_OPTIONAL_HEADER64 *opt = &nt64->OptionalHeader; /* Skip CheckSum */ efi_image_region_add(regs, efi, &opt->CheckSum, 0); if (nt64->OptionalHeader.NumberOfRvaAndSizes <= ctidx) { efi_image_region_add(regs, &opt->CheckSum + 1, efi + opt->SizeOfHeaders, 0); } else { /* Skip Certificates Table */ efi_image_region_add(regs, &opt->CheckSum + 1, &opt->DataDirectory[ctidx], 0); efi_image_region_add(regs, &opt->DataDirectory[ctidx] + 1, efi + opt->SizeOfHeaders, 0); } bytes_hashed = opt->SizeOfHeaders; align = opt->FileAlignment; authoff = opt->DataDirectory[ctidx].VirtualAddress; authsz = opt->DataDirectory[ctidx].Size; } else if (nt->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR32_MAGIC) { IMAGE_OPTIONAL_HEADER32 *opt = &nt->OptionalHeader; efi_image_region_add(regs, efi, &opt->CheckSum, 0); efi_image_region_add(regs, &opt->CheckSum + 1, &opt->DataDirectory[ctidx], 0); efi_image_region_add(regs, &opt->DataDirectory[ctidx] + 1, efi + opt->SizeOfHeaders, 0); bytes_hashed = opt->SizeOfHeaders; align = opt->FileAlignment; authoff = opt->DataDirectory[ctidx].VirtualAddress; authsz = opt->DataDirectory[ctidx].Size; } else { debug("%s: Invalid optional header magic %x\n", __func__, nt->OptionalHeader.Magic); goto err; } /* 2. Sections */ num_sections = nt->FileHeader.NumberOfSections; sections = (void *)((uint8_t *)&nt->OptionalHeader + nt->FileHeader.SizeOfOptionalHeader); sorted = calloc(sizeof(IMAGE_SECTION_HEADER *), num_sections); if (!sorted) { debug("%s: Out of memory\n", __func__); goto err; } /* * Make sure the section list is in ascending order. */ for (i = 0; i < num_sections; i++) sorted[i] = §ions[i]; qsort(sorted, num_sections, sizeof(sorted[0]), cmp_pe_section); for (i = 0; i < num_sections; i++) { if (!sorted[i]->SizeOfRawData) continue; size = (sorted[i]->SizeOfRawData + align - 1) & ~(align - 1); efi_image_region_add(regs, efi + sorted[i]->PointerToRawData, efi + sorted[i]->PointerToRawData + size, 0); debug("section[%d](%s): raw: 0x%x-0x%x, virt: %x-%x\n", i, sorted[i]->Name, sorted[i]->PointerToRawData, sorted[i]->PointerToRawData + size, sorted[i]->VirtualAddress, sorted[i]->VirtualAddress + sorted[i]->Misc.VirtualSize); bytes_hashed += size; } free(sorted); /* 3. Extra data excluding Certificates Table */ if (bytes_hashed + authsz < len) { debug("extra data for hash: %lu\n", len - (bytes_hashed + authsz)); efi_image_region_add(regs, efi + bytes_hashed, efi + len - authsz, 0); } /* Return Certificates Table */ if (authsz) { if (len < authoff + authsz) { debug("%s: Size for auth too large: %u >= %zu\n", __func__, authsz, len - authoff); goto err; } if (authsz < sizeof(*auth)) { debug("%s: Size for auth too small: %u < %zu\n", __func__, authsz, sizeof(*auth)); goto err; } *auth = efi + authoff; *auth_len = authsz; debug("WIN_CERTIFICATE: 0x%x, size: 0x%x\n", authoff, authsz); } else { *auth = NULL; *auth_len = 0; } *regp = regs; return true; err: free(regs); return false; } /** * efi_image_unsigned_authenticate - authenticate unsigned image with * SHA256 hash * @regs: List of regions to be verified * * If an image is not signed, it doesn't have a signature. In this case, * its message digest is calculated and it will be compared with one of * hash values stored in signature databases. * * Return: true if authenticated, false if not */ static bool efi_image_unsigned_authenticate(struct efi_image_regions *regs) { struct efi_signature_store *db = NULL, *dbx = NULL; bool ret = false; dbx = efi_sigstore_parse_sigdb(L"dbx"); if (!dbx) { debug("Getting signature database(dbx) failed\n"); goto out; } db = efi_sigstore_parse_sigdb(L"db"); if (!db) { debug("Getting signature database(db) failed\n"); goto out; } /* try black-list first */ if (efi_signature_verify_with_sigdb(regs, NULL, dbx, NULL)) { debug("Image is not signed and rejected by \"dbx\"\n"); goto out; } /* try white-list */ if (efi_signature_verify_with_sigdb(regs, NULL, db, NULL)) ret = true; else debug("Image is not signed and not found in \"db\" or \"dbx\"\n"); out: efi_sigstore_free(db); efi_sigstore_free(dbx); return ret; } /** * efi_image_authenticate - verify a signature of signed image * @efi: Pointer to image * @efi_size: Size of @efi * * A signed image should have its signature stored in a table of its PE header. * So if an image is signed and only if if its signature is verified using * signature databases, an image is authenticated. * If an image is not signed, its validity is checked by using * efi_image_unsigned_authenticated(). * TODO: * When AuditMode==0, if the image's signature is not found in * the authorized database, or is found in the forbidden database, * the image will not be started and instead, information about it * will be placed in this table. * When AuditMode==1, an EFI_IMAGE_EXECUTION_INFO element is created * in the EFI_IMAGE_EXECUTION_INFO_TABLE for every certificate found * in the certificate table of every image that is validated. * * Return: true if authenticated, false if not */ static bool efi_image_authenticate(void *efi, size_t efi_size) { struct efi_image_regions *regs = NULL; WIN_CERTIFICATE *wincerts = NULL, *wincert; size_t wincerts_len; struct pkcs7_message *msg = NULL; struct efi_signature_store *db = NULL, *dbx = NULL; struct x509_certificate *cert = NULL; void *new_efi = NULL; size_t new_efi_size; bool ret = false; if (!efi_secure_boot_enabled()) return true; /* * Size must be 8-byte aligned and the trailing bytes must be * zero'ed. Otherwise hash value may be incorrect. */ if (efi_size & 0x7) { new_efi_size = (efi_size + 0x7) & ~0x7ULL; new_efi = calloc(new_efi_size, 1); if (!new_efi) return false; memcpy(new_efi, efi, efi_size); efi = new_efi; efi_size = new_efi_size; } if (!efi_image_parse(efi, efi_size, ®s, &wincerts, &wincerts_len)) { debug("Parsing PE executable image failed\n"); goto err; } if (!wincerts) { /* The image is not signed */ ret = efi_image_unsigned_authenticate(regs); goto err; } /* * verify signature using db and dbx */ db = efi_sigstore_parse_sigdb(L"db"); if (!db) { debug("Getting signature database(db) failed\n"); goto err; } dbx = efi_sigstore_parse_sigdb(L"dbx"); if (!dbx) { debug("Getting signature database(dbx) failed\n"); goto err; } /* go through WIN_CERTIFICATE list */ for (wincert = wincerts; (void *)wincert < (void *)wincerts + wincerts_len; wincert = (void *)wincert + ALIGN(wincert->dwLength, 8)) { if (wincert->dwLength < sizeof(*wincert)) { debug("%s: dwLength too small: %u < %zu\n", __func__, wincert->dwLength, sizeof(*wincert)); goto err; } msg = pkcs7_parse_message((void *)wincert + sizeof(*wincert), wincert->dwLength - sizeof(*wincert)); if (IS_ERR(msg)) { debug("Parsing image's signature failed\n"); msg = NULL; goto err; } /* try black-list first */ if (efi_signature_verify_with_sigdb(regs, msg, dbx, NULL)) { debug("Signature was rejected by \"dbx\"\n"); goto err; } if (!efi_signature_verify_signers(msg, dbx)) { debug("Signer was rejected by \"dbx\"\n"); goto err; } else { ret = true; } /* try white-list */ if (!efi_signature_verify_with_sigdb(regs, msg, db, &cert)) { debug("Verifying signature with \"db\" failed\n"); goto err; } else { ret = true; } if (!efi_signature_verify_cert(cert, dbx)) { debug("Certificate was rejected by \"dbx\"\n"); goto err; } else { ret = true; } } err: x509_free_certificate(cert); efi_sigstore_free(db); efi_sigstore_free(dbx); pkcs7_free_message(msg); free(regs); free(new_efi); return ret; } #else static bool efi_image_authenticate(void *efi, size_t efi_size) { return true; } #endif /* CONFIG_EFI_SECURE_BOOT */ /** * efi_load_pe() - relocate EFI binary * * This function loads all sections from a PE binary into a newly reserved * piece of memory. On success the entry point is returned as handle->entry. * * @handle: loaded image handle * @efi: pointer to the EFI binary * @efi_size: size of @efi binary * @loaded_image_info: loaded image protocol * Return: status code */ efi_status_t efi_load_pe(struct efi_loaded_image_obj *handle, void *efi, size_t efi_size, struct efi_loaded_image *loaded_image_info) { IMAGE_NT_HEADERS32 *nt; IMAGE_DOS_HEADER *dos; IMAGE_SECTION_HEADER *sections; int num_sections; void *efi_reloc; int i; const IMAGE_BASE_RELOCATION *rel; unsigned long rel_size; int rel_idx = IMAGE_DIRECTORY_ENTRY_BASERELOC; uint64_t image_base; unsigned long virt_size = 0; int supported = 0; efi_status_t ret; /* Sanity check for a file header */ if (efi_size < sizeof(*dos)) { printf("%s: Truncated DOS Header\n", __func__); ret = EFI_LOAD_ERROR; goto err; } dos = efi; if (dos->e_magic != IMAGE_DOS_SIGNATURE) { printf("%s: Invalid DOS Signature\n", __func__); ret = EFI_LOAD_ERROR; goto err; } /* assume sizeof(IMAGE_NT_HEADERS32) <= sizeof(IMAGE_NT_HEADERS64) */ if (efi_size < dos->e_lfanew + sizeof(IMAGE_NT_HEADERS32)) { printf("%s: Invalid offset for Extended Header\n", __func__); ret = EFI_LOAD_ERROR; goto err; } nt = (void *) ((char *)efi + dos->e_lfanew); if ((nt->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR64_MAGIC) && (efi_size < dos->e_lfanew + sizeof(IMAGE_NT_HEADERS64))) { printf("%s: Invalid offset for Extended Header\n", __func__); ret = EFI_LOAD_ERROR; goto err; } if (nt->Signature != IMAGE_NT_SIGNATURE) { printf("%s: Invalid NT Signature\n", __func__); ret = EFI_LOAD_ERROR; goto err; } for (i = 0; machines[i]; i++) if (machines[i] == nt->FileHeader.Machine) { supported = 1; break; } if (!supported) { printf("%s: Machine type 0x%04x is not supported\n", __func__, nt->FileHeader.Machine); ret = EFI_LOAD_ERROR; goto err; } num_sections = nt->FileHeader.NumberOfSections; sections = (void *)&nt->OptionalHeader + nt->FileHeader.SizeOfOptionalHeader; if (efi_size < ((void *)sections + sizeof(sections[0]) * num_sections - efi)) { printf("%s: Invalid number of sections: %d\n", __func__, num_sections); ret = EFI_LOAD_ERROR; goto err; } /* Authenticate an image */ if (efi_image_authenticate(efi, efi_size)) handle->auth_status = EFI_IMAGE_AUTH_PASSED; else handle->auth_status = EFI_IMAGE_AUTH_FAILED; /* Calculate upper virtual address boundary */ for (i = num_sections - 1; i >= 0; i--) { IMAGE_SECTION_HEADER *sec = §ions[i]; virt_size = max_t(unsigned long, virt_size, sec->VirtualAddress + sec->Misc.VirtualSize); } /* Read 32/64bit specific header bits */ if (nt->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR64_MAGIC) { IMAGE_NT_HEADERS64 *nt64 = (void *)nt; IMAGE_OPTIONAL_HEADER64 *opt = &nt64->OptionalHeader; image_base = opt->ImageBase; efi_set_code_and_data_type(loaded_image_info, opt->Subsystem); handle->image_type = opt->Subsystem; efi_reloc = efi_alloc(virt_size, loaded_image_info->image_code_type); if (!efi_reloc) { printf("%s: Could not allocate %lu bytes\n", __func__, virt_size); ret = EFI_OUT_OF_RESOURCES; goto err; } handle->entry = efi_reloc + opt->AddressOfEntryPoint; rel_size = opt->DataDirectory[rel_idx].Size; rel = efi_reloc + opt->DataDirectory[rel_idx].VirtualAddress; virt_size = ALIGN(virt_size, opt->SectionAlignment); } else if (nt->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR32_MAGIC) { IMAGE_OPTIONAL_HEADER32 *opt = &nt->OptionalHeader; image_base = opt->ImageBase; efi_set_code_and_data_type(loaded_image_info, opt->Subsystem); handle->image_type = opt->Subsystem; efi_reloc = efi_alloc(virt_size, loaded_image_info->image_code_type); if (!efi_reloc) { printf("%s: Could not allocate %lu bytes\n", __func__, virt_size); ret = EFI_OUT_OF_RESOURCES; goto err; } handle->entry = efi_reloc + opt->AddressOfEntryPoint; rel_size = opt->DataDirectory[rel_idx].Size; rel = efi_reloc + opt->DataDirectory[rel_idx].VirtualAddress; virt_size = ALIGN(virt_size, opt->SectionAlignment); } else { printf("%s: Invalid optional header magic %x\n", __func__, nt->OptionalHeader.Magic); ret = EFI_LOAD_ERROR; goto err; } /* Copy PE headers */ memcpy(efi_reloc, efi, sizeof(*dos) + sizeof(*nt) + nt->FileHeader.SizeOfOptionalHeader + num_sections * sizeof(IMAGE_SECTION_HEADER)); /* Load sections into RAM */ for (i = num_sections - 1; i >= 0; i--) { IMAGE_SECTION_HEADER *sec = §ions[i]; memset(efi_reloc + sec->VirtualAddress, 0, sec->Misc.VirtualSize); memcpy(efi_reloc + sec->VirtualAddress, efi + sec->PointerToRawData, sec->SizeOfRawData); } /* Run through relocations */ if (efi_loader_relocate(rel, rel_size, efi_reloc, (unsigned long)image_base) != EFI_SUCCESS) { efi_free_pages((uintptr_t) efi_reloc, (virt_size + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT); ret = EFI_LOAD_ERROR; goto err; } /* Flush cache */ flush_cache((ulong)efi_reloc, ALIGN(virt_size, EFI_CACHELINE_SIZE)); invalidate_icache_all(); /* Populate the loaded image interface bits */ loaded_image_info->image_base = efi_reloc; loaded_image_info->image_size = virt_size; if (handle->auth_status == EFI_IMAGE_AUTH_PASSED) return EFI_SUCCESS; else return EFI_SECURITY_VIOLATION; err: return ret; }