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bootloader_support: Move secure boot code to bootloader_support

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Angus Gratton
2016-11-02 17:54:47 +11:00
parent aceb6517c0
commit 98a0387854
5 changed files with 85 additions and 82 deletions
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202
components/bootloader_support/src/secure_boot.c Normal file
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// 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 <string.h>
#include "esp_attr.h"
#include "esp_types.h"
#include "esp_log.h"
#include "rom/cache.h"
#include "rom/ets_sys.h"
#include "rom/spi_flash.h"
#include "rom/secure_boot.h"
#include "soc/dport_reg.h"
#include "soc/io_mux_reg.h"
#include "soc/efuse_reg.h"
#include "soc/rtc_cntl_reg.h"
#include "sdkconfig.h"
#include "bootloader_flash.h"
#include "esp_image_format.h"
#include "esp_secure_boot.h"
static const char* TAG = "secure_boot";
#define HASH_BLOCK_SIZE 128
#define IV_LEN HASH_BLOCK_SIZE
#define DIGEST_LEN 64
/**
* @function : secure_boot_generate
* @description: generate boot digest (aka "abstract") & iv
*
* @inputs: image_len - length of image to calculate digest for
*/
static bool secure_boot_generate(uint32_t image_len){
SpiFlashOpResult spiRet;
/* buffer is uint32_t not uint8_t to meet ROM SPI API signature */
uint32_t buf[IV_LEN / sizeof(uint32_t)];
const void *image;
/* hardware secure boot engine only takes full blocks, so round up the
image length. The additional data should all be 0xFF.
*/
if (image_len % HASH_BLOCK_SIZE != 0) {
image_len = (image_len / HASH_BLOCK_SIZE + 1) * HASH_BLOCK_SIZE;
}
ets_secure_boot_start();
ets_secure_boot_rd_iv(buf);
ets_secure_boot_hash(NULL);
Cache_Read_Disable(0);
/* iv stored in sec 0 */
spiRet = SPIEraseSector(0);
if (spiRet != SPI_FLASH_RESULT_OK)
{
ESP_LOGE(TAG, "SPI erase failed %d", spiRet);
return false;
}
Cache_Read_Enable(0);
/* write iv to flash, 0x0000, 128 bytes (1024 bits) */
ESP_LOGD(TAG, "write iv to flash.");
spiRet = SPIWrite(0, buf, IV_LEN);
if (spiRet != SPI_FLASH_RESULT_OK)
{
ESP_LOGE(TAG, "SPI write failed %d", spiRet);
return false;
}
bzero(buf, sizeof(buf));
/* generate digest from image contents */
image = bootloader_mmap(0x1000, image_len);
if (!image) {
ESP_LOGE(TAG, "bootloader_mmap(0x1000, 0x%x) failed", image_len);
return false;
}
for (int i = 0; i < image_len; i+= HASH_BLOCK_SIZE) {
ets_secure_boot_hash(image + i/sizeof(void *));
}
bootloader_unmap(image);
ets_secure_boot_obtain();
ets_secure_boot_rd_abstract(buf);
ets_secure_boot_finish();
ESP_LOGD(TAG, "write digest to flash.");
spiRet = SPIWrite(0x80, buf, DIGEST_LEN);
if (spiRet != SPI_FLASH_RESULT_OK) {
ESP_LOGE(TAG, "SPI write failed %d", spiRet);
return false;
}
ESP_LOGD(TAG, "write digest to flash.");
Cache_Read_Enable(0);
return true;
}
/* Burn values written to the efuse write registers */
static inline void burn_efuses()
{
REG_WRITE(EFUSE_CONF_REG, 0x5A5A); /* efuse_pgm_op_ena, force no rd/wr disable */
REG_WRITE(EFUSE_CMD_REG, 0x02); /* efuse_pgm_cmd */
while (REG_READ(EFUSE_CMD_REG)); /* wait for efuse_pagm_cmd=0 */
REG_WRITE(EFUSE_CONF_REG, 0x5AA5); /* efuse_read_op_ena, release force */
REG_WRITE(EFUSE_CMD_REG, 0x01); /* efuse_read_cmd */
while (REG_READ(EFUSE_CMD_REG)); /* wait for efuse_read_cmd=0 */
}
esp_err_t esp_secure_boot_permanently_enable(void) {
esp_err_t err;
uint32_t image_len = 0;
if (esp_secure_boot_enabled())
{
ESP_LOGI(TAG, "bootloader secure boot is already enabled, continuing..");
return ESP_OK;
}
err = esp_image_basic_verify(0x1000, &image_len);
if (err != ESP_OK) {
ESP_LOGE(TAG, "bootloader image appears invalid! error %d", err);
return err;
}
uint32_t dis_reg = REG_READ(EFUSE_BLK0_RDATA0_REG);
bool efuse_key_read_protected = dis_reg & EFUSE_RD_DIS_BLK2;
bool efuse_key_write_protected = dis_reg & EFUSE_WR_DIS_BLK2;
if (efuse_key_read_protected == false
&& efuse_key_write_protected == false
&& REG_READ(EFUSE_BLK2_RDATA0_REG) == 0
&& REG_READ(EFUSE_BLK2_RDATA1_REG) == 0
&& REG_READ(EFUSE_BLK2_RDATA2_REG) == 0
&& REG_READ(EFUSE_BLK2_RDATA3_REG) == 0
&& REG_READ(EFUSE_BLK2_RDATA4_REG) == 0
&& REG_READ(EFUSE_BLK2_RDATA5_REG) == 0
&& REG_READ(EFUSE_BLK2_RDATA6_REG) == 0
&& REG_READ(EFUSE_BLK2_RDATA7_REG) == 0) {
ESP_LOGI(TAG, "Generating new secure boot key...");
/* reuse the secure boot IV generation function to generate
the key, as this generator uses the hardware RNG. */
uint32_t buf[32];
ets_secure_boot_start();
ets_secure_boot_rd_iv(buf);
ets_secure_boot_finish();
for (int i = 0; i < 8; i++) {
ESP_LOGV(TAG, "EFUSE_BLK2_WDATA%d_REG = 0x%08x", i, buf[i]);
REG_WRITE(EFUSE_BLK2_WDATA0_REG + 4*i, buf[i]);
}
bzero(buf, sizeof(buf));
burn_efuses();
ESP_LOGI(TAG, "Read & write protecting new key...");
REG_WRITE(EFUSE_BLK0_WDATA0_REG, EFUSE_WR_DIS_BLK2 | EFUSE_RD_DIS_BLK2);
burn_efuses();
efuse_key_read_protected = true;
efuse_key_write_protected = true;
} else {
ESP_LOGW(TAG, "Using pre-loaded secure boot key in EFUSE block 2");
}
ESP_LOGI(TAG, "Generating secure boot digest...");
if (false == secure_boot_generate(image_len)){
ESP_LOGE(TAG, "secure boot generation failed");
return ESP_FAIL;
}
ESP_LOGI(TAG, "Digest generation complete.");
if (!efuse_key_read_protected) {
ESP_LOGE(TAG, "Pre-loaded key is not read protected. Refusing to blow secure boot efuse.");
return ESP_ERR_INVALID_STATE;
}
if (!efuse_key_write_protected) {
ESP_LOGE(TAG, "Pre-loaded key is not write protected. Refusing to blow secure boot efuse.");
return ESP_ERR_INVALID_STATE;
}
ESP_LOGI(TAG, "blowing secure boot efuse & disabling JTAG...");
ESP_LOGD(TAG, "before updating, EFUSE_BLK0_RDATA6 %x", REG_READ(EFUSE_BLK0_RDATA6_REG));
REG_WRITE(EFUSE_BLK0_WDATA6_REG,
EFUSE_RD_ABS_DONE_0 | EFUSE_RD_DISABLE_JTAG);
burn_efuses();
uint32_t after = REG_READ(EFUSE_BLK0_RDATA6_REG);
ESP_LOGD(TAG, "after updating, EFUSE_BLK0_RDATA6 %x", after);
if (after & EFUSE_RD_ABS_DONE_0) {
ESP_LOGI(TAG, "secure boot is now enabled for bootloader image");
return ESP_OK;
} else {
ESP_LOGE(TAG, "secure boot not enabled for bootloader image, EFUSE_RD_ABS_DONE_0 is probably write protected!");
return ESP_ERR_INVALID_STATE;
}
}