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88 lines
3.1 KiB
C
88 lines
3.1 KiB
C
// Copyright 2018 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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//
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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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#include <string.h>
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#include "esp_spi_flash.h"
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#include "esp32/rom/spi_flash.h"
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#include "esp32/rom/cache.h"
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static inline void IRAM_ATTR spi_flash_guard_start(void)
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{
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const spi_flash_guard_funcs_t *ops = spi_flash_guard_get();
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if (ops && ops->start) {
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ops->start();
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}
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}
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static inline void IRAM_ATTR spi_flash_guard_end(void)
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{
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const spi_flash_guard_funcs_t *ops = spi_flash_guard_get();
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if (ops && ops->end) {
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ops->end();
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}
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}
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extern void IRAM_ATTR flash_rom_init(void);
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esp_rom_spiflash_result_t IRAM_ATTR spi_flash_write_encrypted_chip(size_t dest_addr, const void *src, size_t size)
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{
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const uint8_t *ssrc = (const uint8_t *)src;
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esp_rom_spiflash_result_t rc = ESP_ROM_SPIFLASH_RESULT_OK;
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assert((dest_addr % 16) == 0);
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assert((size % 16) == 0);
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/* esp_rom_spiflash_write_encrypted encrypts data in RAM as it writes,
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so copy to a temporary buffer - 32 bytes at a time.
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Each call to esp_rom_spiflash_write_encrypted takes a 32 byte "row" of
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data to encrypt, and each row is two 16 byte AES blocks
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that share a key (as derived from flash address).
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*/
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uint8_t encrypt_buf[32] __attribute__((aligned(4)));
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uint32_t row_size;
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for (size_t i = 0; i < size; i += row_size) {
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uint32_t row_addr = dest_addr + i;
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if (i == 0 && (row_addr % 32) != 0) {
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/* writing to second block of a 32 byte row */
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row_size = 16;
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row_addr -= 16;
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/* copy to second block in buffer */
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memcpy(encrypt_buf + 16, ssrc + i, 16);
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/* decrypt the first block from flash, will reencrypt to same bytes */
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spi_flash_read_encrypted(row_addr, encrypt_buf, 16);
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} else if (size - i == 16) {
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/* 16 bytes left, is first block of a 32 byte row */
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row_size = 16;
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/* copy to first block in buffer */
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memcpy(encrypt_buf, ssrc + i, 16);
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/* decrypt the second block from flash, will reencrypt to same bytes */
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spi_flash_read_encrypted(row_addr + 16, encrypt_buf + 16, 16);
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} else {
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/* Writing a full 32 byte row (2 blocks) */
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row_size = 32;
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memcpy(encrypt_buf, ssrc + i, 32);
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}
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spi_flash_guard_start();
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flash_rom_init();
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rc = esp_rom_spiflash_write_encrypted(row_addr, (uint32_t *)encrypt_buf, 32);
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spi_flash_guard_end();
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if (rc != ESP_ROM_SPIFLASH_RESULT_OK) {
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break;
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}
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}
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bzero(encrypt_buf, sizeof(encrypt_buf));
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return rc;
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}
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