mirror of
https://github.com/espressif/esp-idf.git
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125 lines
3.9 KiB
C
125 lines
3.9 KiB
C
// Copyright 2017 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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#include "bootloader_sha.h"
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#include <stdbool.h>
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#include <string.h>
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#include <assert.h>
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#include <sys/param.h>
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#include "esp32/rom/sha.h"
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#include "soc/dport_reg.h"
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#include "soc/hwcrypto_periph.h"
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static uint32_t words_hashed;
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// Words per SHA256 block
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static const size_t BLOCK_WORDS = (64 / sizeof(uint32_t));
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// Words in final SHA256 digest
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static const size_t DIGEST_WORDS = (32 / sizeof(uint32_t));
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bootloader_sha256_handle_t bootloader_sha256_start(void)
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{
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// Enable SHA hardware
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ets_sha_enable();
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words_hashed = 0;
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return (bootloader_sha256_handle_t)&words_hashed; // Meaningless non-NULL value
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}
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void bootloader_sha256_data(bootloader_sha256_handle_t handle, const void *data, size_t data_len)
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{
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assert(handle != NULL);
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assert(data_len % 4 == 0);
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const uint32_t *w = (const uint32_t *)data;
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size_t word_len = data_len / 4;
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uint32_t *sha_text_reg = (uint32_t *)(SHA_TEXT_BASE);
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while (word_len > 0) {
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size_t block_count = words_hashed % BLOCK_WORDS;
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size_t copy_words = (BLOCK_WORDS - block_count);
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copy_words = MIN(word_len, copy_words);
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// Wait for SHA engine idle
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while (REG_READ(SHA_256_BUSY_REG) != 0) { }
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// Copy to memory block
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for (size_t i = 0; i < copy_words; i++) {
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sha_text_reg[block_count + i] = __builtin_bswap32(w[i]);
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}
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asm volatile ("memw");
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// Update counters
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words_hashed += copy_words;
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block_count += copy_words;
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word_len -= copy_words;
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w += copy_words;
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// If we loaded a full block, run the SHA engine
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if (block_count == BLOCK_WORDS) {
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if (words_hashed == BLOCK_WORDS) {
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REG_WRITE(SHA_256_START_REG, 1);
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} else {
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REG_WRITE(SHA_256_CONTINUE_REG, 1);
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}
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block_count = 0;
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}
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}
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}
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void bootloader_sha256_finish(bootloader_sha256_handle_t handle, uint8_t *digest)
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{
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assert(handle != NULL);
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if (digest == NULL) {
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return; // We'd free resources here, but there are none to free
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}
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uint32_t data_words = words_hashed;
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// Pad to a 55 byte long block loaded in the engine
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// (leaving 1 byte 0x80 plus variable padding plus 8 bytes of length,
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// to fill a 64 byte block.)
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int block_bytes = (words_hashed % BLOCK_WORDS) * 4;
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int pad_bytes = 55 - block_bytes;
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if (pad_bytes < 0) {
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pad_bytes += 64;
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}
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static const uint8_t padding[64] = { 0x80, 0, };
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pad_bytes += 5; // 1 byte for 0x80 plus first 4 bytes of the 64-bit length
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assert(pad_bytes % 4 == 0); // should be, as (block_bytes % 4 == 0)
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bootloader_sha256_data(handle, padding, pad_bytes);
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assert(words_hashed % BLOCK_WORDS == 60 / 4); // 32-bits left in block
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// Calculate 32-bit length for final 32 bits of data
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uint32_t bit_count = __builtin_bswap32( data_words * 32 );
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bootloader_sha256_data(handle, &bit_count, sizeof(bit_count));
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assert(words_hashed % BLOCK_WORDS == 0);
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while (REG_READ(SHA_256_BUSY_REG) == 1) { }
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REG_WRITE(SHA_256_LOAD_REG, 1);
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while (REG_READ(SHA_256_BUSY_REG) == 1) { }
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uint32_t *digest_words = (uint32_t *)digest;
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uint32_t *sha_text_reg = (uint32_t *)(SHA_TEXT_BASE);
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for (size_t i = 0; i < DIGEST_WORDS; i++) {
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digest_words[i] = __builtin_bswap32(sha_text_reg[i]);
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}
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asm volatile ("memw");
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}
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