| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| |
| /* |
| * Original code taken from mcuboot project at: |
| * https://github.com/JuulLabs-OSS/mcuboot |
| * Git SHA of the original version: 178be54bd6e5f035cc60e98205535682acd26e64 |
| * Modifications are Copyright (c) 2018-2019 Arm Limited. |
| */ |
| |
| #include <assert.h> |
| #include <stddef.h> |
| #include <inttypes.h> |
| #include <string.h> |
| |
| #include "flash_map/flash_map.h" |
| #include "bootutil/image.h" |
| #include "bootutil/sha256.h" |
| #include "bootutil/sign_key.h" |
| |
| #ifdef MCUBOOT_SIGN_RSA |
| #include "mbedtls/rsa.h" |
| #endif |
| |
| #include "mbedtls/asn1.h" |
| |
| #include "bootutil_priv.h" |
| |
| /* |
| * Compute SHA256 over the image. |
| */ |
| static int |
| bootutil_img_hash(struct image_header *hdr, const struct flash_area *fap, |
| uint8_t *tmp_buf, uint32_t tmp_buf_sz, |
| uint8_t *hash_result, uint8_t *seed, int seed_len) |
| { |
| bootutil_sha256_context sha256_ctx; |
| uint32_t blk_sz; |
| uint32_t size; |
| uint32_t off; |
| |
| bootutil_sha256_init(&sha256_ctx); |
| |
| /* in some cases (split image) the hash is seeded with data from |
| * the loader image */ |
| if (seed && (seed_len > 0)) { |
| bootutil_sha256_update(&sha256_ctx, seed, seed_len); |
| } |
| |
| /* Hash is computed over image header and image itself. */ |
| size = hdr->ih_img_size + hdr->ih_hdr_size; |
| |
| /* If a security counter TLV is present then the TLV info header and the |
| * security counter are also protected and must be included in the hash |
| * calculation. |
| */ |
| if (hdr->ih_protect_tlv_size != 0) { |
| size += hdr->ih_protect_tlv_size; |
| } |
| |
| for (off = 0; off < size; off += blk_sz) { |
| blk_sz = size - off; |
| if (blk_sz > tmp_buf_sz) { |
| blk_sz = tmp_buf_sz; |
| } |
| |
| #ifdef MCUBOOT_RAM_LOADING |
| if (fap == NULL) { /* The image is in SRAM */ |
| memcpy(tmp_buf, (uint32_t *)(hdr->ih_load_addr + off), blk_sz); |
| } else { /* The image is in flash */ |
| #endif |
| if(flash_area_read(fap, off, tmp_buf, blk_sz)) { |
| return -1; |
| } |
| #ifdef MCUBOOT_RAM_LOADING |
| } |
| #endif |
| |
| bootutil_sha256_update(&sha256_ctx, tmp_buf, blk_sz); |
| } |
| bootutil_sha256_finish(&sha256_ctx, hash_result); |
| |
| return 0; |
| } |
| |
| /* |
| * Currently, we only support being able to verify one type of |
| * signature, because there is a single verification function that we |
| * call. List the type of TLV we are expecting. If we aren't |
| * configured for any signature, don't define this macro. |
| */ |
| #if defined(MCUBOOT_SIGN_RSA) |
| # define EXPECTED_SIG_TLV IMAGE_TLV_RSA2048_PSS |
| # define EXPECTED_SIG_LEN(x) ((x) == 256) /* 2048 bits */ |
| #endif |
| |
| #ifdef EXPECTED_SIG_TLV |
| static int |
| bootutil_find_key(uint8_t *keyhash, uint8_t keyhash_len) |
| { |
| bootutil_sha256_context sha256_ctx; |
| int i; |
| const struct bootutil_key *key; |
| uint8_t hash[32]; |
| |
| assert(keyhash_len <= 32); |
| |
| for (i = 0; i < bootutil_key_cnt; i++) { |
| key = &bootutil_keys[i]; |
| bootutil_sha256_init(&sha256_ctx); |
| bootutil_sha256_update(&sha256_ctx, key->key, *key->len); |
| bootutil_sha256_finish(&sha256_ctx, hash); |
| if (!memcmp(hash, keyhash, keyhash_len)) { |
| return i; |
| } |
| } |
| return -1; |
| } |
| #endif |
| |
| #ifdef MCUBOOT_RAM_LOADING |
| /* Check the hash of an image after it has been copied to SRAM */ |
| int |
| bootutil_check_hash_after_loading(struct image_header *hdr) |
| { |
| uint32_t off; |
| uint32_t end; |
| int sha256_valid = 0; |
| struct image_tlv_info info; |
| struct image_tlv tlv; |
| uint8_t tmp_buf[BOOT_TMPBUF_SZ]; |
| uint8_t hash[32] = {0}; |
| int rc; |
| uint32_t load_address; |
| uint32_t tlv_sz; |
| |
| rc = bootutil_img_hash(hdr, NULL, tmp_buf, BOOT_TMPBUF_SZ, hash, NULL, 0); |
| |
| if (rc) { |
| return rc; |
| } |
| |
| load_address = (uint32_t) hdr->ih_load_addr; |
| |
| /* The TLVs come after the image. */ |
| off = hdr->ih_img_size + hdr->ih_hdr_size; |
| |
| info = *((struct image_tlv_info *)(load_address + off)); |
| |
| if (info.it_magic != IMAGE_TLV_INFO_MAGIC) { |
| return -1; |
| } |
| end = off + info.it_tlv_tot; |
| off += sizeof(info); |
| |
| /* |
| * Traverse through all of the TLVs, performing any checks we know |
| * and are able to do. |
| */ |
| for (; off < end; off += sizeof(tlv) + tlv.it_len) { |
| tlv = *((struct image_tlv *)(load_address + off)); |
| tlv_sz = sizeof(tlv); |
| |
| if (tlv.it_type == IMAGE_TLV_SHA256) { |
| /* |
| * Verify the SHA256 image hash. This must always be present. |
| */ |
| if (tlv.it_len != sizeof(hash)) { |
| return -1; |
| } |
| |
| if (memcmp(hash, (uint32_t *)(load_address + off + tlv_sz), |
| sizeof(hash))) { |
| return -1; |
| } |
| |
| sha256_valid = 1; |
| } |
| } |
| |
| if (!sha256_valid) { |
| return -1; |
| } |
| |
| return 0; |
| } |
| #endif /* MCUBOOT_RAM_LOADING */ |
| |
| /* |
| * Verify the integrity of the image. |
| * Return non-zero if image could not be validated/does not validate. |
| */ |
| int |
| bootutil_img_validate(struct image_header *hdr, const struct flash_area *fap, |
| uint8_t *tmp_buf, uint32_t tmp_buf_sz, |
| uint8_t *seed, int seed_len, uint8_t *out_hash) |
| { |
| uint32_t off; |
| uint32_t end; |
| int sha256_valid = 0; |
| struct image_tlv_info info; |
| #ifdef EXPECTED_SIG_TLV |
| int valid_signature = 0; |
| int key_id = -1; |
| #endif |
| struct image_tlv tlv; |
| uint8_t buf[256]; |
| uint8_t hash[32] = {0}; |
| int rc; |
| |
| rc = bootutil_img_hash(hdr, fap, tmp_buf, tmp_buf_sz, hash, |
| seed, seed_len); |
| if (rc) { |
| return rc; |
| } |
| |
| if (out_hash) { |
| memcpy(out_hash, hash, 32); |
| } |
| |
| /* The TLVs come after the image. */ |
| off = hdr->ih_img_size + hdr->ih_hdr_size; |
| |
| rc = flash_area_read(fap, off, &info, sizeof(info)); |
| if (rc) { |
| return rc; |
| } |
| if (info.it_magic != IMAGE_TLV_INFO_MAGIC) { |
| return -1; |
| } |
| end = off + info.it_tlv_tot; |
| off += sizeof(info); |
| |
| /* |
| * Traverse through all of the TLVs, performing any checks we know |
| * and are able to do. |
| */ |
| for (; off < end; off += sizeof(tlv) + tlv.it_len) { |
| rc = flash_area_read(fap, off, &tlv, sizeof(tlv)); |
| if (rc) { |
| return rc; |
| } |
| |
| if (tlv.it_type == IMAGE_TLV_SHA256) { |
| /* |
| * Verify the SHA256 image hash. This must always be |
| * present. |
| */ |
| if (tlv.it_len != sizeof(hash)) { |
| return -1; |
| } |
| rc = flash_area_read(fap, off + sizeof(tlv), buf, sizeof(hash)); |
| if (rc) { |
| return rc; |
| } |
| if (memcmp(hash, buf, sizeof(hash))) { |
| return -1; |
| } |
| |
| sha256_valid = 1; |
| #ifdef EXPECTED_SIG_TLV |
| } else if (tlv.it_type == IMAGE_TLV_KEYHASH) { |
| /* |
| * Determine which key we should be checking. |
| */ |
| if (tlv.it_len > 32) { |
| return -1; |
| } |
| rc = flash_area_read(fap, off + sizeof(tlv), buf, tlv.it_len); |
| if (rc) { |
| return rc; |
| } |
| key_id = bootutil_find_key(buf, tlv.it_len); |
| /* |
| * The key may not be found, which is acceptable. There |
| * can be multiple signatures, each preceded by a key. |
| */ |
| } else if (tlv.it_type == EXPECTED_SIG_TLV) { |
| /* Ignore this signature if it is out of bounds. */ |
| if (key_id < 0 || key_id >= bootutil_key_cnt) { |
| key_id = -1; |
| continue; |
| } |
| if (!EXPECTED_SIG_LEN(tlv.it_len) || tlv.it_len > sizeof(buf)) { |
| return -1; |
| } |
| rc = flash_area_read(fap, off + sizeof(tlv), buf, tlv.it_len); |
| if (rc) { |
| return -1; |
| } |
| rc = bootutil_verify_sig(hash, sizeof(hash), buf, tlv.it_len, |
| key_id); |
| if (rc == 0) { |
| valid_signature = 1; |
| } |
| key_id = -1; |
| #endif |
| } |
| } |
| |
| if (!sha256_valid) { |
| return -1; |
| } |
| |
| #ifdef EXPECTED_SIG_TLV |
| if (!valid_signature) { |
| return -1; |
| } |
| #endif |
| |
| return 0; |
| } |