| /* |
| * 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. |
| */ |
| |
| #include <assert.h> |
| #include <stddef.h> |
| #include <inttypes.h> |
| #include <string.h> |
| |
| #include "os/mynewt.h" |
| #include "hal/hal_flash.h" |
| #include "hal/hal_watchdog.h" |
| #include "flash_map/flash_map.h" |
| #include "bootutil/image.h" |
| #include "bootutil/sign_key.h" |
| |
| #include "mbedtls/sha256.h" |
| #include "mbedtls/rsa.h" |
| #include "mbedtls/ecdsa.h" |
| #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) |
| { |
| mbedtls_sha256_context sha256_ctx; |
| uint32_t blk_sz; |
| uint32_t size; |
| uint32_t off; |
| int rc; |
| |
| mbedtls_sha256_init(&sha256_ctx); |
| mbedtls_sha256_starts(&sha256_ctx, 0); |
| |
| /* in some cases (split image) the hash is seeded with data from |
| * the loader image */ |
| if(seed && (seed_len > 0)) { |
| mbedtls_sha256_update(&sha256_ctx, seed, seed_len); |
| } |
| |
| size = hdr->ih_img_size + hdr->ih_hdr_size; |
| |
| /* |
| * Hash is computed over image header and image itself. No TLV is |
| * included ATM. |
| */ |
| size = hdr->ih_img_size + hdr->ih_hdr_size; |
| for (off = 0; off < size; off += blk_sz) { |
| /* Pet the watchdog, in case it is still enabled after a soft reset. */ |
| hal_watchdog_tickle(); |
| |
| blk_sz = size - off; |
| if (blk_sz > tmp_buf_sz) { |
| blk_sz = tmp_buf_sz; |
| } |
| rc = flash_area_read(fap, off, tmp_buf, blk_sz); |
| if (rc) { |
| return rc; |
| } |
| mbedtls_sha256_update(&sha256_ctx, tmp_buf, blk_sz); |
| } |
| mbedtls_sha256_finish(&sha256_ctx, hash_result); |
| |
| return 0; |
| } |
| |
| /* |
| * 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 size; |
| uint32_t sha_off = 0; |
| #if MYNEWT_VAL(BOOTUTIL_SIGN_RSA) || MYNEWT_VAL(BOOTUTIL_SIGN_EC) || \ |
| MYNEWT_VAL(BOOTUTIL_SIGN_EC256) |
| uint32_t sig_off = 0; |
| uint32_t sig_len = 0; |
| #endif |
| struct image_tlv tlv; |
| uint8_t buf[256]; |
| uint8_t hash[32]; |
| int rc; |
| |
| #if MYNEWT_VAL(BOOTUTIL_SIGN_RSA) |
| if ((hdr->ih_flags & IMAGE_F_PKCS15_RSA2048_SHA256) == 0) { |
| return -1; |
| } |
| #endif |
| #if MYNEWT_VAL(BOOTUTIL_SIGN_EC) |
| if ((hdr->ih_flags & IMAGE_F_ECDSA224_SHA256) == 0) { |
| return -1; |
| } |
| #endif |
| #if MYNEWT_VAL(BOOTUTIL_SIGN_EC256) |
| if ((hdr->ih_flags & IMAGE_F_ECDSA256_SHA256) == 0) { |
| return -1; |
| } |
| #endif |
| if ((hdr->ih_flags & IMAGE_F_SHA256) == 0) { |
| return -1; |
| } |
| |
| 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); |
| } |
| |
| /* After image there are TLVs. */ |
| off = hdr->ih_img_size + hdr->ih_hdr_size; |
| size = off + hdr->ih_tlv_size; |
| |
| for (; off < size; 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) { |
| if (tlv.it_len != sizeof(hash)) { |
| return -1; |
| } |
| sha_off = off + sizeof(tlv); |
| } |
| #if MYNEWT_VAL(BOOTUTIL_SIGN_RSA) |
| if (tlv.it_type == IMAGE_TLV_RSA2048) { |
| if (tlv.it_len != 256) { /* 2048 bits */ |
| return -1; |
| } |
| sig_off = off + sizeof(tlv); |
| sig_len = tlv.it_len; |
| } |
| #endif |
| #if MYNEWT_VAL(BOOTUTIL_SIGN_EC) |
| if (tlv.it_type == IMAGE_TLV_ECDSA224) { |
| if (tlv.it_len < 64) { /* oids + 2 * 28 bytes */ |
| return -1; |
| } |
| sig_off = off + sizeof(tlv); |
| sig_len = tlv.it_len; |
| } |
| #endif |
| #if MYNEWT_VAL(BOOTUTIL_SIGN_EC256) |
| if (tlv.it_type == IMAGE_TLV_ECDSA256) { |
| if (tlv.it_len < 72) { /* oids + 2 * 32 bytes */ |
| return -1; |
| } |
| sig_off = off + sizeof(tlv); |
| sig_len = tlv.it_len; |
| } |
| #endif |
| } |
| if (hdr->ih_flags & IMAGE_F_SHA256) { |
| if (!sha_off) { |
| /* |
| * Header said there should be hash TLV, no TLV found. |
| */ |
| return -1; |
| } |
| rc = flash_area_read(fap, sha_off, buf, sizeof hash); |
| if (rc) { |
| return rc; |
| } |
| if (memcmp(hash, buf, sizeof(hash))) { |
| return -1; |
| } |
| } |
| #if MYNEWT_VAL(BOOTUTIL_SIGN_RSA) || MYNEWT_VAL(BOOTUTIL_SIGN_EC) || \ |
| MYNEWT_VAL(BOOTUTIL_SIGN_EC256) |
| if (!sig_off) { |
| /* |
| * Header said there should be PKCS1.v5 signature, no TLV |
| * found. |
| */ |
| return -1; |
| } |
| rc = flash_area_read(fap, sig_off, buf, sig_len); |
| if (rc) { |
| return -1; |
| } |
| |
| if (hdr->ih_key_id >= bootutil_key_cnt) { |
| return -1; |
| } |
| rc = bootutil_verify_sig(hash, sizeof(hash), buf, sig_len, hdr->ih_key_id); |
| if (rc) { |
| return -1; |
| } |
| #endif |
| return 0; |
| } |
