esp-idf/components/bootloader_support/include/esp_secure_boot.h
2022-11-03 08:36:23 +00:00

275 lines
10 KiB
C

/*
* SPDX-FileCopyrightText: 2015-2022 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#pragma once
#include <stdbool.h>
#include <esp_err.h>
#include "soc/efuse_periph.h"
#include "soc/soc_caps.h"
#include "esp_image_format.h"
#include "esp_rom_efuse.h"
#include "sdkconfig.h"
#include "esp_rom_crc.h"
#include "hal/efuse_ll.h"
#ifdef CONFIG_SECURE_BOOT_V1_ENABLED
#if !defined(CONFIG_SECURE_SIGNED_ON_BOOT) || !defined(CONFIG_SECURE_SIGNED_ON_UPDATE) || !defined(CONFIG_SECURE_SIGNED_APPS)
#error "internal sdkconfig error, secure boot should always enable all signature options"
#endif
#endif
#ifdef __cplusplus
extern "C" {
#endif
/* Support functions for secure boot features.
Can be compiled as part of app or bootloader code.
*/
#define ESP_SECURE_BOOT_DIGEST_LEN 32
#if CONFIG_IDF_TARGET_ESP32C2
#define ESP_SECURE_BOOT_KEY_DIGEST_LEN 16
#else
#define ESP_SECURE_BOOT_KEY_DIGEST_LEN 32
#endif
#ifdef CONFIG_EFUSE_VIRTUAL_KEEP_IN_FLASH
#include "esp_efuse.h"
#include "esp_efuse_table.h"
#endif
/** @brief Is secure boot currently enabled in hardware?
*
* This means that the ROM bootloader code will only boot
* a verified secure bootloader from now on.
*
* @return true if secure boot is enabled.
*/
static inline bool esp_secure_boot_enabled(void)
{
#if CONFIG_IDF_TARGET_ESP32
#ifdef CONFIG_SECURE_BOOT_V1_ENABLED
#ifndef CONFIG_EFUSE_VIRTUAL_KEEP_IN_FLASH
return efuse_ll_get_secure_boot_v1_en();
#else
return esp_efuse_read_field_bit(ESP_EFUSE_ABS_DONE_0);
#endif
#elif CONFIG_SECURE_BOOT_V2_ENABLED
#ifndef CONFIG_EFUSE_VIRTUAL_KEEP_IN_FLASH
return efuse_ll_get_secure_boot_v2_en();
#else
return esp_efuse_read_field_bit(ESP_EFUSE_ABS_DONE_1);
#endif
#endif
#else
#ifndef CONFIG_EFUSE_VIRTUAL_KEEP_IN_FLASH
return efuse_ll_get_secure_boot_v2_en();
#else
return esp_efuse_read_field_bit(ESP_EFUSE_SECURE_BOOT_EN);
#endif
#endif
return false; /* Secure Boot not enabled in menuconfig */
}
/** @brief Generate secure digest from bootloader image
*
* @important This function is intended to be called from bootloader code only.
*
* This function is only used in the context of the Secure Boot V1 scheme.
*
* If secure boot is not yet enabled for bootloader, this will:
* 1) generate the secure boot key and burn it on EFUSE
* (without enabling R/W protection)
* 2) generate the digest from bootloader and save it
* to flash address 0x0
*
* If first boot gets interrupted after calling this function
* but before esp_secure_boot_permanently_enable() is called, then
* the key burned on EFUSE will not be regenerated, unless manually
* done using espefuse.py tool
*
* @return ESP_OK if secure boot digest is generated
* successfully or found to be already present
*/
esp_err_t esp_secure_boot_generate_digest(void);
/** @brief Enable secure boot V1 if it is not already enabled.
*
* @important If this function succeeds, secure boot V1 is permanently
* enabled on the chip via efuse.
*
* @important This function is intended to be called from bootloader code only.
*
* @important In case of Secure Boot V1, this will enable r/w protection
* of secure boot key on EFUSE, therefore it is to be ensured that
* esp_secure_boot_generate_digest() is called before this .If secure boot is not
* yet enabled for bootloader, this will
* 1) enable R/W protection of secure boot key on EFUSE
* 2) enable secure boot by blowing the EFUSE_RD_ABS_DONE_0 efuse.
*
* This function does not verify secure boot of the bootloader (the
* ROM bootloader does this.)
*
* Will fail if efuses have been part-burned in a way that indicates
* secure boot should not or could not be correctly enabled.
*
* @return ESP_ERR_INVALID_STATE if efuse state doesn't allow
* secure boot to be enabled cleanly. ESP_OK if secure boot
* is enabled on this chip from now on.
*/
esp_err_t esp_secure_boot_permanently_enable(void);
/** @brief Enables secure boot V2 if it is not already enabled.
*
* @important If this function succeeds, secure boot V2 is permanently
* enabled on the chip via efuse.
*
* @important This function is intended to be called from bootloader code only.
*
* @important In case of Secure Boot V2, this will enable write protection
* of secure boot key on EFUSE in BLK2. .If secure boot is not
* yet enabled for bootloader, this will
* 1) enable W protection of secure boot key on EFUSE
* 2) enable secure boot by blowing the EFUSE_RD_ABS_DONE_1 efuse.
*
* This function does not verify secure boot of the bootloader (the
* ROM bootloader does this.)
*
* @param image_data Image metadata of the application to be loaded.
*
* Will fail if efuses have been part-burned in a way that indicates
* secure boot should not or could not be correctly enabled.
*
* @return ESP_ERR_INVALID_STATE if efuse state doesn't allow
* secure boot to be enabled cleanly. ESP_OK if secure boot
* is enabled on this chip from now on.
*/
esp_err_t esp_secure_boot_v2_permanently_enable(const esp_image_metadata_t *image_data);
/** @brief Verify the secure boot signature appended to some binary data in flash.
*
* For ECDSA Scheme (Secure Boot V1) - deterministic ECDSA w/ SHA256 image
* For RSA Scheme (Secure Boot V2) - RSA-PSS Verification of the SHA-256 image
*
* Public key is compiled into the calling program in the ECDSA Scheme.
* See the apt docs/security/secure-boot-v1.rst or docs/security/secure-boot-v2.rst for details.
*
* @param src_addr Starting offset of the data in flash.
* @param length Length of data in bytes. Signature is appended -after- length bytes.
*
* If flash encryption is enabled, the image will be transparently decrypted while being verified.
*
* @note This function doesn't have any fault injection resistance so should not be called
* during a secure boot itself (but can be called when verifying an update, etc.)
*
* @return ESP_OK if signature is valid, ESP_ERR_INVALID_STATE if
* signature fails, ESP_FAIL for other failures (ie can't read flash).
*/
esp_err_t esp_secure_boot_verify_signature(uint32_t src_addr, uint32_t length);
/** @brief Secure boot verification block, on-flash data format. */
typedef struct {
uint32_t version;
uint8_t signature[64];
} esp_secure_boot_sig_block_t;
/** @brief Verify the ECDSA secure boot signature block for Secure Boot V1.
*
* Calculates Deterministic ECDSA w/ SHA256 based on the SHA256 hash of the image. ECDSA signature
* verification must be enabled in project configuration to use this function.
*
* Similar to esp_secure_boot_verify_signature(), but can be used when the digest is precalculated.
* @param sig_block Pointer to ECDSA signature block data
* @param image_digest Pointer to 32 byte buffer holding SHA-256 hash.
* @param verified_digest Pointer to 32 byte buffer that will receive verified digest if verification completes. (Used during bootloader implementation only, result is invalid otherwise.)
*
*/
esp_err_t esp_secure_boot_verify_ecdsa_signature_block(const esp_secure_boot_sig_block_t *sig_block, const uint8_t *image_digest, uint8_t *verified_digest);
#if !CONFIG_IDF_TARGET_ESP32 || CONFIG_ESP32_REV_MIN_FULL >= 300
/**
* @brief Structure to hold public key digests calculated from the signature blocks of a single image.
*
* Each image can have one or more signature blocks (up to SECURE_BOOT_NUM_BLOCKS). Each signature block includes a public key.
*/
typedef struct {
uint8_t key_digests[SOC_EFUSE_SECURE_BOOT_KEY_DIGESTS][ESP_SECURE_BOOT_DIGEST_LEN]; /* SHA of the public key components in the signature block */
unsigned num_digests; /* Number of valid digests, starting at index 0 */
} esp_image_sig_public_key_digests_t;
#endif // !CONFIG_IDF_TARGET_ESP32 || CONFIG_ESP32_REV_MIN_FULL >= 300
/** @brief Legacy ECDSA verification function
*
* @note Deprecated, call either esp_secure_boot_verify_ecdsa_signature_block() or esp_secure_boot_verify_rsa_signature_block() instead.
*
* @param sig_block Pointer to ECDSA signature block data
* @param image_digest Pointer to 32 byte buffer holding SHA-256 hash.
*/
esp_err_t esp_secure_boot_verify_signature_block(const esp_secure_boot_sig_block_t *sig_block, const uint8_t *image_digest)
__attribute__((deprecated("use esp_secure_boot_verify_ecdsa_signature_block instead")));
#define FLASH_OFFS_SECURE_BOOT_IV_DIGEST 0
/** @brief Secure boot IV+digest header */
typedef struct {
uint8_t iv[128];
uint8_t digest[64];
} esp_secure_boot_iv_digest_t;
/** @brief Check the secure boot V2 during startup
*
* @note This function is called automatically during app startup,
* it doesn't need to be called from the app.
*
* Verifies the secure boot config during startup:
*
* - Correct any insecure secure boot settings
*/
void esp_secure_boot_init_checks(void);
#if !BOOTLOADER_BUILD && (CONFIG_SECURE_SIGNED_APPS_RSA_SCHEME || CONFIG_SECURE_SIGNED_APPS_ECDSA_V2_SCHEME)
/** @brief Scan the current running app for signature blocks
*
* @note This function doesn't verify that the signatures are valid or the
* corresponding public keys are trusted, it only reads the number of signature
* blocks present and optionally calculates the digests of the public keys
* provided in the signature blocks.
*
* @param digest_public_keys If true, the key_digests fields in the
* public_key_digests structure will be filled with the digests of the public
* key provided in each signature block. Note that if Secure Boot V2 is enabled,
* each public key will only be trusted if the same digest is also present in
* eFuse (but this is not checked by this function).
*
* @param public_key_digests[out] Structure is initialized with the num_digests
* field set to the number of signatures found. If digest_public_keys is set,
* the public key digests are also calculated and stored here.
*
* @return
* - ESP_OK - At least one signature was found
* - ESP_ERR_NOT_FOUND - No signatures were found, num_digests value will be zero
* - ESP_FAIL - An error occured trying to read the signature blocks from flash
*/
esp_err_t esp_secure_boot_get_signature_blocks_for_running_app(bool digest_public_keys, esp_image_sig_public_key_digests_t *public_key_digests);
#endif // !BOOTLOADER_BUILD && (CONFIG_SECURE_SIGNED_APPS_RSA_SCHEME || CONFIG_SECURE_SIGNED_APPS_ECDSA_V2_SCHEME)
/** @brief Set all secure eFuse features related to secure_boot
*
* @return
* - ESP_OK - Successfully
*/
esp_err_t esp_secure_boot_enable_secure_features(void);
#ifdef __cplusplus
}
#endif