b364f23e17
Allows OTA updates to be secured via signature checks, without requiring the overhead or complexity of a full secure boot implementation. Uses same signing mechanisms (build system and/or espsecure.py as Secure Boot). Requires: * [ ] More testing * [ ] Documentation
116 lines
3.9 KiB
C
116 lines
3.9 KiB
C
// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#pragma once
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#include <stdbool.h>
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#include <esp_err.h>
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#include "soc/efuse_reg.h"
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#include "sdkconfig.h"
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#ifdef CONFIG_SECURE_BOOT_ENABLED
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#if !defined(CONFIG_SECURE_SIGNED_ON_BOOT) || !defined(CONFIG_SECURE_SIGNED_ON_UPDATE) || !defined(CONFIG_SECURE_SIGNED_APPS)
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#error "internal sdkconfig error, secure boot should always enable all signature options"
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#endif
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#endif
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Support functions for secure boot features.
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Can be compiled as part of app or bootloader code.
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*/
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/** @brief Is secure boot currently enabled in hardware?
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*
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* Secure boot is enabled if the ABS_DONE_0 efuse is blown. This means
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* that the ROM bootloader code will only boot a verified secure
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* bootloader digest from now on.
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*
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* @return true if secure boot is enabled.
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*/
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static inline bool esp_secure_boot_enabled(void) {
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return REG_READ(EFUSE_BLK0_RDATA6_REG) & EFUSE_RD_ABS_DONE_0;
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}
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/** @brief Enable secure boot if it is not already enabled.
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*
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* @important If this function succeeds, secure boot is permanently
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* enabled on the chip via efuse.
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*
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* @important This function is intended to be called from bootloader code only.
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*
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* If secure boot is not yet enabled for bootloader, this will
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* generate the secure boot digest and enable secure boot by blowing
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* the EFUSE_RD_ABS_DONE_0 efuse.
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*
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* This function does not verify secure boot of the bootloader (the
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* ROM bootloader does this.)
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*
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* Will fail if efuses have been part-burned in a way that indicates
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* secure boot should not or could not be correctly enabled.
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*
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*
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* @return ESP_ERR_INVALID_STATE if efuse state doesn't allow
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* secure boot to be enabled cleanly. ESP_OK if secure boot
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* is enabled on this chip from now on.
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*/
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esp_err_t esp_secure_boot_permanently_enable(void);
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/** @brief Verify the secure boot signature (determinstic ECDSA w/ SHA256) appended to some binary data in flash.
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*
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* Public key is compiled into the calling program. See docs/security/secure-boot.rst for details.
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*
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* @param src_addr Starting offset of the data in flash.
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* @param length Length of data in bytes. Signature is appended -after- length bytes.
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*
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* If flash encryption is enabled, the image will be transparently decrypted while being verified.
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*
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* @return ESP_OK if signature is valid, ESP_ERR_INVALID_STATE if
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* signature fails, ESP_FAIL for other failures (ie can't read flash).
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*/
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esp_err_t esp_secure_boot_verify_signature(uint32_t src_addr, uint32_t length);
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/** @brief Verify the secure boot signature block (deterministic ECDSA w/ SHA256) based on the SHA256 hash of some data.
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*
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* Similar to esp_secure_boot_verify_signature(), but can be used when the digest is precalculated.
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* @param sig_block Pointer to signature block data
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* @param image_digest Pointer to 32 byte buffer holding SHA-256 hash.
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*
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*/
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/** @brief Secure boot verification block, on-flash data format. */
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typedef struct {
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uint32_t version;
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uint8_t signature[64];
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} esp_secure_boot_sig_block_t;
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esp_err_t esp_secure_boot_verify_signature_block(const esp_secure_boot_sig_block_t *sig_block, const uint8_t *image_digest);
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#define FLASH_OFFS_SECURE_BOOT_IV_DIGEST 0
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/** @brief Secure boot IV+digest header */
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typedef struct {
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uint8_t iv[128];
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uint8_t digest[64];
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} esp_secure_boot_iv_digest_t;
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#ifdef __cplusplus
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}
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#endif
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