esp-idf/components/bootloader_support/src/secure_boot_signatures.c
Angus Gratton 9eb135fd73 Flash encryption: Support enabling flash encryption in bootloader, app support
* App access functions are all flash encryption-aware
* Documentation for flash encryption
* Partition read/write is flash aware
* New encrypted write function
2016-12-01 23:49:12 -08:00

103 lines
3.2 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 "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 "hwcrypto/sha.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
esp_err_t esp_secure_boot_verify_signature(uint32_t src_addr, uint32_t length)
{
#ifdef BOOTLOADER_BUILD
SHA_CTX sha;
#endif
uint8_t digest[32];
ptrdiff_t keylen;
const uint8_t *data;
const esp_secure_boot_sig_block_t *sigblock;
bool is_valid;
#ifdef BOOTLOADER_BUILD
const uint8_t *digest_data;
uint32_t digest_len;
#endif
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;
}
sigblock = (const esp_secure_boot_sig_block_t *)(data + length);
if (sigblock->version != 0) {
ESP_LOGE(TAG, "src 0x%x has invalid signature version field 0x%08x", src_addr, sigblock->version);
goto unmap_and_fail;
}
#ifdef BOOTLOADER_BUILD
/* Use ROM SHA functions directly */
ets_sha_enable();
ets_sha_init(&sha);
digest_len = length * 8;
digest_data = data;
while (digest_len > 0) {
uint32_t chunk_len = (digest_len > 64) ? 64 : digest_len;
ets_sha_update(&sha, SHA2_256, digest_data, chunk_len);
digest_len -= chunk_len;
digest_data += chunk_len / 8;
}
ets_sha_finish(&sha, SHA2_256, digest);
ets_sha_disable();
#else
/* Use thread-safe esp-idf SHA function */
esp_sha(SHA2_256, data, length, digest);
#endif
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);
goto unmap_and_fail;
}
is_valid = uECC_verify(signature_verification_key_start,
digest, sizeof(digest), sigblock->signature,
uECC_secp256r1());
bootloader_munmap(data);
return is_valid ? ESP_OK : ESP_ERR_IMAGE_INVALID;
unmap_and_fail:
bootloader_munmap(data);
return ESP_FAIL;
}