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Merge branch 'bugfix/secure_boot_sig_verify' into 'master'

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secure boot: Fix incorrect handling of mbedtls_ctr_drbg_seed() failure in signature verification

See merge request espressif/esp-idf!14300
This commit is contained in:
Angus Gratton
2021-07-13 06:48:25 +00:00
parent 4fe4df8770 e92c4106b9
commit d7d28786b2
7 changed files with 134 additions and 53 deletions
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13
components/bootloader_support/src/secure_boot_v2/secure_boot_signatures_app.c
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@@ -182,7 +182,7 @@ esp_err_t esp_secure_boot_verify_rsa_signature_block(const ets_secure_boot_signa
ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy, NULL, 0); ret = mbedtls_ctr_drbg_seed(&ctr_drbg, mbedtls_entropy_func, &entropy, NULL, 0);
if (ret != 0) { if (ret != 0) {
ESP_LOGE(TAG, "mbedtls_ctr_drbg_seed returned -0x%04x\n", ret); ESP_LOGE(TAG, "mbedtls_ctr_drbg_seed returned -0x%04x\n", ret);
goto exit; goto exit_outer;
} }
#ifdef CONFIG_SECURE_SIGNED_ON_UPDATE_NO_SECURE_BOOT #ifdef CONFIG_SECURE_SIGNED_ON_UPDATE_NO_SECURE_BOOT
@@ -234,19 +234,19 @@ esp_err_t esp_secure_boot_verify_rsa_signature_block(const ets_secure_boot_signa
ret = mbedtls_rsa_import(&pk, &N, NULL, NULL, NULL, &e); ret = mbedtls_rsa_import(&pk, &N, NULL, NULL, NULL, &e);
if (ret != 0) { if (ret != 0) {
ESP_LOGE(TAG, "Failed mbedtls_rsa_import, err: %d", ret); ESP_LOGE(TAG, "Failed mbedtls_rsa_import, err: %d", ret);
goto exit; goto exit_inner;
} }
ret = mbedtls_rsa_complete(&pk); ret = mbedtls_rsa_complete(&pk);
if (ret != 0) { if (ret != 0) {
ESP_LOGE(TAG, "Failed mbedtls_rsa_complete, err: %d", ret); ESP_LOGE(TAG, "Failed mbedtls_rsa_complete, err: %d", ret);
goto exit; goto exit_inner;
} }
ret = mbedtls_rsa_check_pubkey(&pk); ret = mbedtls_rsa_check_pubkey(&pk);
if (ret != 0) { if (ret != 0) {
ESP_LOGI(TAG, "Key is not an RSA key -%0x", -ret); ESP_LOGI(TAG, "Key is not an RSA key -%0x", -ret);
goto exit; goto exit_inner;
} }
/* Signature needs to be byte swapped into BE representation */ /* Signature needs to be byte swapped into BE representation */
@@ -257,7 +257,7 @@ esp_err_t esp_secure_boot_verify_rsa_signature_block(const ets_secure_boot_signa
ret = mbedtls_rsa_public( &pk, sig_be, buf); ret = mbedtls_rsa_public( &pk, sig_be, buf);
if (ret != 0) { if (ret != 0) {
ESP_LOGE(TAG, "mbedtls_rsa_public failed, err: %d", ret); ESP_LOGE(TAG, "mbedtls_rsa_public failed, err: %d", ret);
goto exit; goto exit_inner;
} }
ret = mbedtls_rsa_rsassa_pss_verify( &pk, mbedtls_ctr_drbg_random, &ctr_drbg, MBEDTLS_RSA_PUBLIC, MBEDTLS_MD_SHA256, ESP_SECURE_BOOT_DIGEST_LEN, ret = mbedtls_rsa_rsassa_pss_verify( &pk, mbedtls_ctr_drbg_random, &ctr_drbg, MBEDTLS_RSA_PUBLIC, MBEDTLS_MD_SHA256, ESP_SECURE_BOOT_DIGEST_LEN,
@@ -267,13 +267,14 @@ esp_err_t esp_secure_boot_verify_rsa_signature_block(const ets_secure_boot_signa
} else { } else {
ESP_LOGI(TAG, "Signature verified successfully!"); ESP_LOGI(TAG, "Signature verified successfully!");
} }
exit: exit_inner:
mbedtls_rsa_free(&pk); mbedtls_rsa_free(&pk);
if (ret == 0) { if (ret == 0) {
break; break;
} }
} }
exit_outer:
free(sig_be); free(sig_be);
free(buf); free(buf);
return (ret != 0 || any_trusted_key == false) ? ESP_ERR_IMAGE_INVALID: ESP_OK; return (ret != 0 || any_trusted_key == false) ? ESP_ERR_IMAGE_INVALID: ESP_OK;

4
tools/test_apps/security/secure_boot/README.md
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@@ -1,5 +1,5 @@
| Supported Targets | ESP32 | | Supported Targets | ESP32 | ESP32-S2 |
| ----------------- | ----- | | ----------------- | ----- | -------- |
# Secure Boot # Secure Boot

10
tools/test_apps/security/secure_boot/main/CMakeLists.txt
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@@ -1,2 +1,8 @@
idf_component_register(SRCS "secure_boot_main.c"
INCLUDE_DIRS ".") if(CONFIG_IDF_TARGET_ESP32)
set(main_src "secure_boot_main_esp32.c")
else()
set(main_src "secure_boot_main.c")
endif()
idf_component_register(SRCS "${main_src}" INCLUDE_DIRS ".")

59
tools/test_apps/security/secure_boot/main/secure_boot_main.c
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@@ -11,6 +11,7 @@
#include "freertos/task.h" #include "freertos/task.h"
#include "soc/efuse_reg.h" #include "soc/efuse_reg.h"
#include "esp_efuse.h" #include "esp_efuse.h"
#include "esp_secure_boot.h"
#include "esp_system.h" #include "esp_system.h"
#include "esp_spi_flash.h" #include "esp_spi_flash.h"
#include "esp_log.h" #include "esp_log.h"
@@ -36,10 +37,7 @@ static void example_print_chip_info(void)
/* Print chip information */ /* Print chip information */
esp_chip_info_t chip_info; esp_chip_info_t chip_info;
esp_chip_info(&chip_info); esp_chip_info(&chip_info);
printf("This is ESP32 chip with %d CPU cores, WiFi%s%s, ", printf("This is %s chip with %d CPU cores\n", CONFIG_IDF_TARGET, chip_info.cores);
chip_info.cores,
(chip_info.features & CHIP_FEATURE_BT) ? "/BT" : "",
(chip_info.features & CHIP_FEATURE_BLE) ? "/BLE" : "");
printf("silicon revision %d, ", chip_info.revision); printf("silicon revision %d, ", chip_info.revision);
@@ -51,46 +49,23 @@ static void example_print_chip_info(void)
static void example_secure_boot_status(void) static void example_secure_boot_status(void)
{ {
uint32_t efuse_block0 = REG_READ(EFUSE_BLK0_RDATA6_REG); ets_secure_boot_key_digests_t trusted_keys = { 0};
#ifdef CONFIG_ESP32_REV_MIN_3 ESP_LOGI(TAG, "Checking for Secure Boot..");
uint8_t efuse_trusted_digest[DIGEST_LEN] = {0}, i; if(esp_secure_boot_enabled()) {
ESP_LOGI(TAG, "Checking for secure boot v2.."); ESP_LOGI(TAG, "Secure Boot is enabled");
if(efuse_block0 & EFUSE_RD_ABS_DONE_1) { ESP_ERROR_CHECK( esp_secure_boot_read_key_digests(&trusted_keys) );
ESP_LOGI(TAG, "ABS_DONE_1 is set. Secure Boot V2 enabled");
memcpy(efuse_trusted_digest, (uint8_t *)EFUSE_BLK2_RDATA0_REG, DIGEST_LEN); unsigned total = 0;
ESP_LOGI(TAG, "Reading the public key digest from BLK2."); for (int i = 0; i < MAX_KEY_DIGESTS; i++) {
for (i = 0; i < DIGEST_LEN; i++) { ESP_LOGI(TAG, "Key slot %d:", i);
ESP_LOGI(TAG, "%02x \t", efuse_trusted_digest[i]); if (trusted_keys.key_digests[i]) {
ESP_LOG_BUFFER_HEXDUMP("trusted key", trusted_keys.key_digests[i], DIGEST_LEN, ESP_LOG_INFO);
total++;
} }
return; }
ESP_LOGI(TAG, "Total %d trusted public keys", total);
} else { } else {
ESP_LOGI(TAG, "Secure boot v2 not enabled. Enable Secure Boot V2 in menuconfig, build & flash again."); ESP_LOGI(TAG, "Secure Boot not enabled. Enable Secure Boot in menuconfig, build & flash again.");
}
#endif
ESP_LOGI(TAG, "Checking for secure boot v1..");
uint32_t dis_reg = REG_READ(EFUSE_BLK0_RDATA0_REG);
if (efuse_block0 & EFUSE_RD_ABS_DONE_0) {
ESP_LOGI(TAG, "ABS_DONE_0 is set. Secure Boot V1 enabled");
#ifdef CONFIG_ESP32_REV_MIN_3
ESP_LOGW(TAG, "This chip version supports Secure Boot V2. It is recommended to use Secure Boot V2.");
#endif
bool efuse_key_read_protected = dis_reg & EFUSE_RD_DIS_BLK2;
bool efuse_key_write_protected = dis_reg & EFUSE_WR_DIS_BLK2;
ESP_LOGI(TAG, "Checking the integrityof the key in BLK2..");
if (!efuse_key_read_protected) {
ESP_LOGE(TAG, "Key is not read protected. Refusing to blow secure boot efuse.");
return;
}
if (!efuse_key_write_protected) {
ESP_LOGE(TAG, "Key is not write protected. Refusing to blow secure boot efuse.");
return;
}
ESP_LOGI(TAG, "Key is read/write protected in eFuse.");
return;
} else {
ESP_LOGI(TAG, "Secure Boot V1 not enabled. Enable Secure Boot in menuconfig, build & flash again.");
} }
} }

96
tools/test_apps/security/secure_boot/main/secure_boot_main_esp32.c Normal file
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@@ -0,0 +1,96 @@
/* Flash encryption Example
This example code is in the Public Domain (or CC0 licensed, at your option.)
Unless required by applicable law or agreed to in writing, this
software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
CONDITIONS OF ANY KIND, either express or implied.
*/
#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "soc/efuse_reg.h"
#include "esp_efuse.h"
#include "esp_system.h"
#include "esp_spi_flash.h"
#include "esp_log.h"
#include "esp_efuse_table.h"
#include <string.h>
static void example_print_chip_info(void);
static void example_secure_boot_status(void);
#define TAG "example_secure_boot"
void app_main(void)
{
printf("\nExample to check Secure Boot status\n");
example_print_chip_info();
example_secure_boot_status();
}
static void example_print_chip_info(void)
{
/* Print chip information */
esp_chip_info_t chip_info;
esp_chip_info(&chip_info);
printf("This is ESP32 chip with %d CPU cores, WiFi%s%s, ",
chip_info.cores,
(chip_info.features & CHIP_FEATURE_BT) ? "/BT" : "",
(chip_info.features & CHIP_FEATURE_BLE) ? "/BLE" : "");
printf("silicon revision %d, ", chip_info.revision);
printf("%dMB %s flash\n", spi_flash_get_chip_size() / (1024 * 1024),
(chip_info.features & CHIP_FEATURE_EMB_FLASH) ? "embedded" : "external");
}
#define DIGEST_LEN 32
static void example_secure_boot_status(void)
{
uint32_t efuse_block0 = REG_READ(EFUSE_BLK0_RDATA6_REG);
#ifdef CONFIG_ESP32_REV_MIN_3
uint8_t efuse_trusted_digest[DIGEST_LEN] = {0}, i;
ESP_LOGI(TAG, "Checking for secure boot v2..");
if(efuse_block0 & EFUSE_RD_ABS_DONE_1) {
ESP_LOGI(TAG, "ABS_DONE_1 is set. Secure Boot V2 enabled");
memcpy(efuse_trusted_digest, (uint8_t *)EFUSE_BLK2_RDATA0_REG, DIGEST_LEN);
ESP_LOGI(TAG, "Reading the public key digest from BLK2.");
for (i = 0; i < DIGEST_LEN; i++) {
ESP_LOGI(TAG, "%02x \t", efuse_trusted_digest[i]);
}
return;
} else {
ESP_LOGI(TAG, "Secure boot v2 not enabled. Enable Secure Boot V2 in menuconfig, build & flash again.");
}
#endif
ESP_LOGI(TAG, "Checking for secure boot v1..");
uint32_t dis_reg = REG_READ(EFUSE_BLK0_RDATA0_REG);
if (efuse_block0 & EFUSE_RD_ABS_DONE_0) {
ESP_LOGI(TAG, "ABS_DONE_0 is set. Secure Boot V1 enabled");
#ifdef CONFIG_ESP32_REV_MIN_3
ESP_LOGW(TAG, "This chip version supports Secure Boot V2. It is recommended to use Secure Boot V2.");
#endif
bool efuse_key_read_protected = dis_reg & EFUSE_RD_DIS_BLK2;
bool efuse_key_write_protected = dis_reg & EFUSE_WR_DIS_BLK2;
ESP_LOGI(TAG, "Checking the integrityof the key in BLK2..");
if (!efuse_key_read_protected) {
ESP_LOGE(TAG, "Key is not read protected. Refusing to blow secure boot efuse.");
return;
}
if (!efuse_key_write_protected) {
ESP_LOGE(TAG, "Key is not write protected. Refusing to blow secure boot efuse.");
return;
}
ESP_LOGI(TAG, "Key is read/write protected in eFuse.");
return;
} else {
ESP_LOGI(TAG, "Secure Boot V1 not enabled. Enable Secure Boot in menuconfig, build & flash again.");
}
}

2
tools/test_apps/security/secure_boot/sdkconfig.ci.04
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@@ -3,4 +3,4 @@ CONFIG_IDF_TARGET="esp32s2"
CONFIG_SECURE_BOOT=y CONFIG_SECURE_BOOT=y
CONFIG_SECURE_BOOT_SIGNING_KEY="test_rsa_3072_key.pem" CONFIG_SECURE_BOOT_SIGNING_KEY="test_rsa_3072_key.pem"
CONFIG_SECURE_FLASH_ENC_ENABLED=y CONFIG_SECURE_FLASH_ENC_ENABLED=y
SECURE_FLASH_ENCRYPTION_MODE_RELEASE=y CONFIG_SECURE_FLASH_ENCRYPTION_MODE_RELEASE=y

3
tools/test_apps/security/secure_boot/sdkconfig.defaults
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@@ -4,3 +4,6 @@
# If you find yourself needing to edit this in the future, it's a sign the # If you find yourself needing to edit this in the future, it's a sign the
# bootloader is bloating out! # bootloader is bloating out!
CONFIG_PARTITION_TABLE_OFFSET=0xC000 CONFIG_PARTITION_TABLE_OFFSET=0xC000
# Maximize the number of possible build warnings
CONFIG_COMPILER_OPTIMIZATION_PERF=y