100 lines
3.1 KiB
C
100 lines
3.1 KiB
C
// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "sdkconfig.h"
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#include "bootloader_flash.h"
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#include "esp_log.h"
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#include "esp_image_format.h"
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#include "esp_secure_boot.h"
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#include "uECC.h"
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#ifdef BOOTLOADER_BUILD
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#include "rom/sha.h"
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typedef SHA_CTX sha_context;
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#else
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#include "hwcrypto/sha.h"
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typedef esp_sha_context sha_context;
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#endif
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typedef struct {
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uint32_t version;
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uint8_t signature[64];
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} signature_block_t;
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static const char* TAG = "secure_boot";
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extern const uint8_t signature_verification_key_start[] asm("_binary_signature_verification_key_bin_start");
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extern const uint8_t signature_verification_key_end[] asm("_binary_signature_verification_key_bin_end");
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#define SIGNATURE_VERIFICATION_KEYLEN 64
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esp_err_t esp_secure_boot_verify_signature(uint32_t src_addr, uint32_t length)
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{
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sha_context sha;
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uint8_t digest[64];
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ptrdiff_t keylen;
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const uint8_t *data;
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const signature_block_t *sigblock;
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bool is_valid;
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ESP_LOGD(TAG, "verifying signature src_addr 0x%x length 0x%x", src_addr, length);
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data = bootloader_mmap(src_addr, length + sizeof(signature_block_t));
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if(data == NULL) {
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ESP_LOGE(TAG, "bootloader_mmap(0x%x, 0x%x) failed", src_addr, length+sizeof(signature_block_t));
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return ESP_FAIL;
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}
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sigblock = (const signature_block_t *)(data + length);
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if (sigblock->version != 0) {
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ESP_LOGE(TAG, "src 0x%x has invalid signature version field 0x%08x", src_addr, sigblock->version);
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goto unmap_and_fail;
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}
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#ifdef BOOTLOADER_BUILD
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/* Use ROM SHA functions directly */
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ets_sha_enable();
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ets_sha_init(&sha);
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ets_sha_update(&sha, SHA2_512, data, length);
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ets_sha_finish(&sha, SHA2_512, digest);
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ets_sha_disable();
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#else
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/* Use thread-safe esp-idf SHA layer */
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esp_sha512_init(&sha);
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esp_sha512_start(&sha, false);
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esp_sha512_update(&sha, data, length);
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esp_sha512_finish(&sha, digest);
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esp_sha512_free(&sha);
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#endif
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keylen = signature_verification_key_end - signature_verification_key_start;
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if(keylen != SIGNATURE_VERIFICATION_KEYLEN) {
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ESP_LOGE(TAG, "Embedded public verification key has wrong length %d", keylen);
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goto unmap_and_fail;
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}
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is_valid = uECC_verify(signature_verification_key_start,
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digest, sizeof(digest), sigblock->signature,
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uECC_secp256r1());
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bootloader_unmap(data);
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return is_valid ? ESP_OK : ESP_ERR_IMAGE_INVALID;
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unmap_and_fail:
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bootloader_unmap(data);
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return ESP_FAIL;
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}
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