esp-idf/components/bootloader_support/src/secure_boot_signatures.c
Angus Gratton 615376d14a secure boot: Use mbedtls_sha256() not esp_sha()
Latter is probably compiled into most firmwares already, saves some size.

Ref https://github.com/espressif/esp-idf/issues/3127
2019-03-15 17:34:06 +11:00

97 lines
3.3 KiB
C

// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
//
// Licensed 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 "sdkconfig.h"
#include "bootloader_flash.h"
#include "bootloader_sha.h"
#include "esp_log.h"
#include "esp_image_format.h"
#include "esp_secure_boot.h"
#include "uECC.h"
#ifdef BOOTLOADER_BUILD
#include "rom/sha.h"
typedef SHA_CTX sha_context;
#else
#include "mbedtls/sha256.h"
#endif
static const char* TAG = "secure_boot";
extern const uint8_t signature_verification_key_start[] asm("_binary_signature_verification_key_bin_start");
extern const uint8_t signature_verification_key_end[] asm("_binary_signature_verification_key_bin_end");
#define SIGNATURE_VERIFICATION_KEYLEN 64
#define DIGEST_LEN 32
esp_err_t esp_secure_boot_verify_signature(uint32_t src_addr, uint32_t length)
{
uint8_t digest[DIGEST_LEN];
const uint8_t *data;
const esp_secure_boot_sig_block_t *sigblock;
ESP_LOGD(TAG, "verifying signature src_addr 0x%x length 0x%x", src_addr, length);
data = bootloader_mmap(src_addr, length + sizeof(esp_secure_boot_sig_block_t));
if(data == NULL) {
ESP_LOGE(TAG, "bootloader_mmap(0x%x, 0x%x) failed", src_addr, length+sizeof(esp_secure_boot_sig_block_t));
return ESP_FAIL;
}
// Calculate digest of main image
#ifdef BOOTLOADER_BUILD
bootloader_sha256_handle_t handle = bootloader_sha256_start();
bootloader_sha256_data(handle, data, length);
bootloader_sha256_finish(handle, digest);
#else
/* Use thread-safe mbedTLS version */
mbedtls_sha256_ret(data, length, digest, 0);
#endif
// Map the signature block and verify the signature
sigblock = (const esp_secure_boot_sig_block_t *)(data + length);
esp_err_t err = esp_secure_boot_verify_signature_block(sigblock, digest);
bootloader_munmap(data);
return err;
}
esp_err_t esp_secure_boot_verify_signature_block(const esp_secure_boot_sig_block_t *sig_block, const uint8_t *image_digest)
{
ptrdiff_t keylen;
bool is_valid;
keylen = signature_verification_key_end - signature_verification_key_start;
if(keylen != SIGNATURE_VERIFICATION_KEYLEN) {
ESP_LOGE(TAG, "Embedded public verification key has wrong length %d", keylen);
return ESP_FAIL;
}
if (sig_block->version != 0) {
ESP_LOGE(TAG, "image has invalid signature version field 0x%08x", sig_block->version);
return ESP_FAIL;
}
ESP_LOGD(TAG, "Verifying secure boot signature");
is_valid = uECC_verify(signature_verification_key_start,
image_digest,
DIGEST_LEN,
sig_block->signature,
uECC_secp256r1());
ESP_LOGD(TAG, "Verification result %d", is_valid);
return is_valid ? ESP_OK : ESP_ERR_IMAGE_INVALID;
}