micropython/ports/stm32/mboot/pack.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2020-2021 Damien P. George
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <string.h>
#include "dfu.h"
#include "gzstream.h"
#include "mboot.h"
#include "pack.h"
#if MBOOT_ENABLE_PACKING
// Keys provided externally by the board, will be built into mboot flash.
#include MBOOT_PACK_KEYS_FILE
// Encrypted dfu files using gzip require a decompress buffer. Larger can be faster.
// This setting is independent to the incoming encrypted/signed/compressed DFU file.
#ifndef MBOOT_PACK_GZIP_BUFFER_SIZE
#define MBOOT_PACK_GZIP_BUFFER_SIZE (2048)
#endif
// State to manage automatic flash erasure.
static uint32_t erased_base_addr;
static uint32_t erased_top_addr;
// DFU chunk buffer, used to cache incoming blocks of data from USB.
static uint32_t firmware_chunk_base_addr;
static mboot_pack_chunk_buf_t firmware_chunk_buf;
// Temporary buffer for decrypted data.
static uint8_t decrypted_buf[MBOOT_PACK_DFU_CHUNK_BUF_SIZE] __attribute__((aligned(8)));
// Temporary buffer for uncompressing.
static uint8_t uncompressed_buf[MBOOT_PACK_GZIP_BUFFER_SIZE] __attribute__((aligned(8)));
// Buffer to hold the start of the firmware, which is only written once the
// entire firmware is validated. This is 8 bytes due to STM32WB MCUs requiring
// that a double-word write to flash can only be done once (due to ECC).
static uint8_t firmware_head[8];
// Flag to indicate that firmware_head contains valid data.
static bool firmware_head_valid;
void mboot_pack_init(void) {
erased_base_addr = 0;
erased_top_addr = 0;
firmware_chunk_base_addr = 0;
firmware_head_valid = false;
}
// In encrypted mode the erase is automatically managed.
// Note: this scheme requires blocks be written in sequence, which is the case.
static int mboot_pack_erase(uint32_t addr, size_t len) {
while (!(erased_base_addr <= addr && addr + len <= erased_top_addr)) {
uint32_t erase;
if (erased_base_addr <= addr && addr < erased_top_addr) {
erase = erased_top_addr;
} else {
erase = addr;
erased_base_addr = addr;
}
uint32_t next_addr;
int ret = hw_page_erase(erase, &next_addr);
if (ret != 0) {
return ret;
}
erased_top_addr = next_addr;
}
return 0;
}
// Commit an unencrypted and uncompressed chunk of firmware to the flash.
static int mboot_pack_commit_chunk(uint32_t addr, uint8_t *data, size_t len) {
// Erase any required sectors before writing.
int ret = mboot_pack_erase(addr, len);
if (ret != 0) {
return ret;
}
if (addr == APPLICATION_ADDR) {
// Don't write the very start of the firmware, just copy it into a temporary buffer.
// It will be written only if the full firmware passes the checksum/signature.
memcpy(firmware_head, data, sizeof(firmware_head));
addr += sizeof(firmware_head);
data += sizeof(firmware_head);
len -= sizeof(firmware_head);
firmware_head_valid = true;
}
// Commit this piece of the firmware.
return hw_write(addr, data, len);
}
// Handle a chunk with the full firmware signature.
static int mboot_pack_handle_full_sig(void) {
if (firmware_chunk_buf.header.length < hydro_sign_BYTES) {
return -MBOOT_ERRNO_PACK_INVALID_CHUNK;
}
uint8_t *full_sig = &firmware_chunk_buf.data[firmware_chunk_buf.header.length - hydro_sign_BYTES];
uint32_t *region_data = (uint32_t *)&firmware_chunk_buf.data[0];
size_t num_regions = (full_sig - (uint8_t *)region_data) / sizeof(uint32_t) / 2;
uint8_t *buf = decrypted_buf;
const size_t buf_alloc = sizeof(decrypted_buf);
// Compute the signature of the full firmware.
hydro_sign_state sign_state;
hydro_sign_init(&sign_state, MBOOT_PACK_HYDRO_CONTEXT);
for (size_t region = 0; region < num_regions; ++region) {
uint32_t addr = region_data[2 * region];
uint32_t len = region_data[2 * region + 1];
while (len) {
uint32_t l = len <= buf_alloc ? len : buf_alloc;
hw_read(addr, l, buf);
if (addr == APPLICATION_ADDR && firmware_head_valid) {
// The start of the firmware was not yet written to flash so copy
// it out of the temporary buffer to compute the full signature.
memcpy(buf, firmware_head, sizeof(firmware_head));
}
int ret = hydro_sign_update(&sign_state, buf, l);
if (ret != 0) {
return -MBOOT_ERRNO_PACK_SIGN_FAILED;
}
addr += l;
len -= l;
}
}
// Verify the signature of the full firmware.
int ret = hydro_sign_final_verify(&sign_state, full_sig, mboot_pack_sign_public_key);
if (ret != 0) {
dfu_context.status = DFU_STATUS_ERROR_VERIFY;
dfu_context.error = MBOOT_ERROR_STR_INVALID_SIG_IDX;
return -MBOOT_ERRNO_PACK_SIGN_FAILED;
}
// Full firmware passed the signature check.
if (firmware_head_valid) {
// Write the start of the firmware so it boots.
ret = hw_write(APPLICATION_ADDR, firmware_head, sizeof(firmware_head));
}
return ret;
}
// Handle a chunk with firmware data.
static int mboot_pack_handle_firmware(void) {
const uint8_t *fw_data = &firmware_chunk_buf.data[0];
const size_t fw_len = firmware_chunk_buf.header.length;
// Decrypt the chunk.
if (hydro_secretbox_decrypt(decrypted_buf, fw_data, fw_len, 0, MBOOT_PACK_HYDRO_CONTEXT, mboot_pack_secretbox_key) != 0) {
dfu_context.status = DFU_STATUS_ERROR_VERIFY;
dfu_context.error = MBOOT_ERROR_STR_INVALID_SIG_IDX;
return -MBOOT_ERRNO_PACK_DECRYPT_FAILED;
}
// Use the decrypted message contents going formward.
size_t len = fw_len - hydro_secretbox_HEADERBYTES;
uint32_t addr = firmware_chunk_buf.header.address;
if (firmware_chunk_buf.header.format == MBOOT_PACK_CHUNK_FW_GZIP) {
// Decompress chunk data.
gz_stream_init_from_raw_data(decrypted_buf, len);
for (;;) {
int read = gz_stream_read(sizeof(uncompressed_buf), uncompressed_buf);
if (read == 0) {
return 0; // finished decompressing
} else if (read < 0) {
return -MBOOT_ERRNO_GUNZIP_FAILED; // error reading
}
int ret = mboot_pack_commit_chunk(addr, uncompressed_buf, read);
if (ret != 0) {
return ret;
}
addr += read;
}
} else {
// Commit chunk data directly.
return mboot_pack_commit_chunk(addr, decrypted_buf, len);
}
}
int mboot_pack_write(uint32_t addr, const uint8_t *src8, size_t len, bool dry_run) {
if (addr == APPLICATION_ADDR) {
// Base address of main firmware, reset any previous state
firmware_chunk_base_addr = 0;
}
if (firmware_chunk_base_addr == 0) {
// First piece of data starting a new chunk, so set the base address.
firmware_chunk_base_addr = addr;
}
if (addr < firmware_chunk_base_addr) {
// Address out of range.
firmware_chunk_base_addr = 0;
return -MBOOT_ERRNO_PACK_INVALID_ADDR;
}
size_t offset = addr - firmware_chunk_base_addr;
if (offset + len > sizeof(firmware_chunk_buf)) {
// Address/length out of range.
firmware_chunk_base_addr = 0;
return -MBOOT_ERRNO_PACK_INVALID_ADDR;
}
// Copy in the new data piece into the chunk buffer.
memcpy((uint8_t *)&firmware_chunk_buf + offset, src8, len);
if (offset + len < sizeof(firmware_chunk_buf.header)) {
// Don't have the header yet.
return 0;
}
if (firmware_chunk_buf.header.header_vers != MBOOT_PACK_HEADER_VERSION) {
// Chunk header has the wrong version.
dfu_context.status = DFU_STATUS_ERROR_FILE;
dfu_context.error = MBOOT_ERROR_STR_INVALID_SIG_IDX;
return -MBOOT_ERRNO_PACK_INVALID_VERSION;
}
if (firmware_chunk_buf.header.address != firmware_chunk_base_addr) {
// Chunk address doesn't agree with dfu address, abort.
dfu_context.status = DFU_STATUS_ERROR_ADDRESS;
dfu_context.error = MBOOT_ERROR_STR_INVALID_SIG_IDX;
return -MBOOT_ERRNO_PACK_INVALID_ADDR;
}
if (offset + len < sizeof(firmware_chunk_buf.header) + firmware_chunk_buf.header.length + sizeof(firmware_chunk_buf.signature)) {
// Don't have the full chunk yet.
return 0;
}
// Have the full chunk in firmware_chunk_buf, process it now.
// Reset the chunk base address for the next chunk that comes in.
firmware_chunk_base_addr = 0;
// Verify the signature of the chunk.
const size_t fw_len = firmware_chunk_buf.header.length;
const uint8_t *sig = &firmware_chunk_buf.data[0] + fw_len;
if (hydro_sign_verify(sig, &firmware_chunk_buf, sizeof(firmware_chunk_buf.header) + fw_len,
MBOOT_PACK_HYDRO_CONTEXT, mboot_pack_sign_public_key) != 0) {
// Signature failed
dfu_context.status = DFU_STATUS_ERROR_VERIFY;
dfu_context.error = MBOOT_ERROR_STR_INVALID_SIG_IDX;
return -MBOOT_ERRNO_PACK_SIGN_FAILED;
}
// Signature passed, we have valid chunk.
if (dry_run) {
return 0;
}
if (firmware_chunk_buf.header.format == MBOOT_PACK_CHUNK_META) {
// Ignore META chunks.
return 0;
} else if (firmware_chunk_buf.header.format == MBOOT_PACK_CHUNK_FULL_SIG) {
return mboot_pack_handle_full_sig();
} else if (firmware_chunk_buf.header.format == MBOOT_PACK_CHUNK_FW_RAW
|| firmware_chunk_buf.header.format == MBOOT_PACK_CHUNK_FW_GZIP) {
return mboot_pack_handle_firmware();
} else {
// Unsupported contents.
return -MBOOT_ERRNO_PACK_INVALID_CHUNK;
}
}
#endif // MBOOT_ENABLE_PACKING