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bootloader: use mbedTLS for secure boot verification in firmware

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This commit is contained in:
Mahavir Jain 2019-01-04 12:48:28 +05:30
parent 369e170ebc
commit 202f689baa
2 changed files with 53 additions and 3 deletions
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1
components/bootloader/Kconfig.projbuild
View file

@ -234,6 +234,7 @@ menu "Security features"
config SECURE_SIGNED_ON_UPDATE
bool
default y
select MBEDTLS_ECP_DP_SECP256R1_ENABLED
depends on SECURE_BOOT_ENABLED || SECURE_SIGNED_ON_UPDATE_NO_SECURE_BOOT
config SECURE_SIGNED_APPS

55
components/bootloader_support/src/secure_boot_signatures.c
View file

@ -19,13 +19,13 @@
#include "esp_image_format.h"
#include "esp_secure_boot.h"
#include "uECC.h"
#ifdef BOOTLOADER_BUILD
#include "esp32/rom/sha.h"
#include "uECC.h"
typedef SHA_CTX sha_context;
#else
#include "mbedtls/sha256.h"
#include "mbedtls/x509.h"
#endif
static const char* TAG = "secure_boot";
@ -71,7 +71,6 @@ esp_err_t esp_secure_boot_verify_signature(uint32_t src_addr, uint32_t length)
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) {
@ -86,6 +85,8 @@ esp_err_t esp_secure_boot_verify_signature_block(const esp_secure_boot_sig_block
ESP_LOGD(TAG, "Verifying secure boot signature");
#ifdef BOOTLOADER_BUILD
bool is_valid;
is_valid = uECC_verify(signature_verification_key_start,
image_digest,
DIGEST_LEN,
@ -93,4 +94,52 @@ esp_err_t esp_secure_boot_verify_signature_block(const esp_secure_boot_sig_block
uECC_secp256r1());
ESP_LOGD(TAG, "Verification result %d", is_valid);
return is_valid ? ESP_OK : ESP_ERR_IMAGE_INVALID;
#else /* BOOTLOADER_BUILD */
int ret;
mbedtls_mpi r, s;
mbedtls_mpi_init(&r);
mbedtls_mpi_init(&s);
/* Extract r and s components from RAW ECDSA signature of 64 bytes */
#define ECDSA_INTEGER_LEN 32
ret = mbedtls_mpi_read_binary(&r, &sig_block->signature[0], ECDSA_INTEGER_LEN);
if (ret != 0) {
ESP_LOGE(TAG, "Failed mbedtls_mpi_read_binary(1), err:%d", ret);
return ESP_FAIL;
}
ret = mbedtls_mpi_read_binary(&s, &sig_block->signature[ECDSA_INTEGER_LEN], ECDSA_INTEGER_LEN);
if (ret != 0) {
ESP_LOGE(TAG, "Failed mbedtls_mpi_read_binary(2), err:%d", ret);
mbedtls_mpi_free(&r);
return ESP_FAIL;
}
/* Initialise ECDSA context */
mbedtls_ecdsa_context ecdsa_context;
mbedtls_ecdsa_init(&ecdsa_context);
mbedtls_ecp_group_load(&ecdsa_context.grp, MBEDTLS_ECP_DP_SECP256R1);
size_t plen = mbedtls_mpi_size(&ecdsa_context.grp.P);
if (keylen != 2*plen) {
ESP_LOGE(TAG, "Incorrect ECDSA key length %d", keylen);
ret = ESP_FAIL;
goto cleanup;
}
/* Extract X and Y components from ECDSA public key */
MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&ecdsa_context.Q.X, signature_verification_key_start, plen));
MBEDTLS_MPI_CHK(mbedtls_mpi_read_binary(&ecdsa_context.Q.Y, signature_verification_key_start + plen, plen));
MBEDTLS_MPI_CHK(mbedtls_mpi_lset(&ecdsa_context.Q.Z, 1));
ret = mbedtls_ecdsa_verify(&ecdsa_context.grp, image_digest, DIGEST_LEN, &ecdsa_context.Q, &r, &s);
ESP_LOGD(TAG, "Verification result %d", ret);
cleanup:
mbedtls_mpi_free(&r);
mbedtls_mpi_free(&s);
mbedtls_ecdsa_free(&ecdsa_context);
return ret == 0 ? ESP_OK : ESP_ERR_IMAGE_INVALID;
#endif /* !BOOTLOADER_BUILD */
}