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trezor-firmware/storage/norcow_blockwise.h

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/*
* This file is part of the Trezor project, https://trezor.io/
*
* Copyright (c) SatoshiLabs
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdbool.h>
#include "flash_area.h"
#define COUNTER_TAIL_WORDS 0
// Small items are encoded more efficiently.
#define NORCOW_SMALL_ITEM_SIZE \
(FLASH_BLOCK_SIZE - NORCOW_LEN_LEN - NORCOW_KEY_LEN)
#define NORCOW_VALID_FLAG 0xFF
#define NORCOW_VALID_FLAG_LEN 1
#define NORCOW_DATA_OPT_SIZE (FLASH_BLOCK_SIZE - NORCOW_VALID_FLAG_LEN)
#define NORCOW_MAX_PREFIX_LEN (FLASH_BLOCK_SIZE + NORCOW_VALID_FLAG_LEN)
/**
* Blockwise NORCOW storage.
*
* The items can have two different formats:
*
* 1. Small items
* Small items are stored in one block, the first two bytes are the key, the
* next two bytes are the length of the value, followed by the value itself.
* This format is used for items with length <= NORCOW_SMALL_ITEM_SIZE.
*
* 2. Large items
* Large items are stored in multiple blocks, the first block contains the key
* and the length of the value.
* Next blocks contain the value itself. If the last value block is not full,
* it includes the valid flag NORCOW_VALID_FLAG. Otherwise the valid flag is
* stored in the next block separately.
* This format is used for items with length > NORCOW_SMALL_ITEM_SIZE.
*
*
* For both formats, the remaining space in the blocks is padded with 0xFF.
*/
// Buffer for update bytes function, used to avoid writing partial blocks
CONFIDENTIAL static flash_block_t norcow_write_buffer = {0};
// Tracks how much data is in the buffer, not yet flashed
CONFIDENTIAL static uint16_t norcow_write_buffer_filled = 0;
// Key of the item being updated, -1 if no update is in progress
CONFIDENTIAL static int32_t norcow_write_buffer_key = -1;
/*
* Writes data to given sector, starting from offset
*/
static secbool write_item(uint8_t sector, uint32_t offset, uint16_t key,
const uint8_t *data, uint16_t len, uint32_t *pos) {
if (sector >= NORCOW_SECTOR_COUNT) {
return secfalse;
}
flash_block_t block = {((uint32_t)len << 16) | key};
if (len <= NORCOW_SMALL_ITEM_SIZE) {
// the whole item fits into one block, let's not waste space
if (offset + FLASH_BLOCK_SIZE > NORCOW_SECTOR_SIZE) {
return secfalse;
}
if (len > 0) {
memcpy(&block[1], data, len); // write data
}
ensure(flash_unlock_write(), NULL);
ensure(flash_area_write_block(&STORAGE_AREAS[sector], offset, block), NULL);
ensure(flash_lock_write(), NULL);
*pos = offset + FLASH_BLOCK_SIZE;
} else {
if (offset + FLASH_ALIGN(NORCOW_MAX_PREFIX_LEN + len) >
NORCOW_SECTOR_SIZE) {
return secfalse;
}
ensure(flash_unlock_write(), NULL);
// write len
ensure(flash_area_write_block(&STORAGE_AREAS[sector], offset, block), NULL);
offset += FLASH_BLOCK_SIZE;
*pos = FLASH_ALIGN(offset + NORCOW_VALID_FLAG_LEN + len);
if (data != NULL) {
// write all blocks except the last one
while ((uint32_t)(len + NORCOW_VALID_FLAG_LEN) > FLASH_BLOCK_SIZE) {
memcpy(block, data, FLASH_BLOCK_SIZE);
ensure(flash_area_write_block(&STORAGE_AREAS[sector], offset, block),
NULL);
offset += FLASH_BLOCK_SIZE;
data += FLASH_BLOCK_SIZE;
len -= FLASH_BLOCK_SIZE;
}
// write the last block
memset(block, 0xFF, sizeof(block));
memcpy(block, data, len);
((uint8_t *)block)[len] = NORCOW_VALID_FLAG;
ensure(flash_area_write_block(&STORAGE_AREAS[sector], offset, block),
NULL);
}
ensure(flash_lock_write(), NULL);
}
return sectrue;
}
/*
* Reads one item starting from offset
*/
static secbool read_item(uint8_t sector, uint32_t offset, uint16_t *key,
const void **val, uint16_t *len, uint32_t *pos) {
*pos = offset;
const void *k = norcow_ptr(sector, *pos, NORCOW_KEY_LEN);
if (k == NULL) {
return secfalse;
}
*pos += NORCOW_KEY_LEN;
const void *l = norcow_ptr(sector, *pos, NORCOW_LEN_LEN);
if (l == NULL) return secfalse;
memcpy(len, l, sizeof(uint16_t));
if (*len <= NORCOW_SMALL_ITEM_SIZE) {
memcpy(key, k, sizeof(uint16_t));
if (*key == NORCOW_KEY_FREE) {
return secfalse;
}
*pos += NORCOW_LEN_LEN;
} else {
*pos = offset + FLASH_BLOCK_SIZE;
uint32_t flg_pos = *pos + *len;
const void *flg = norcow_ptr(sector, flg_pos, NORCOW_VALID_FLAG_LEN);
if (flg == NULL) {
return secfalse;
}
if (*((const uint8_t *)flg) != NORCOW_VALID_FLAG) {
// Deleted item.
*key = NORCOW_KEY_DELETED;
} else {
memcpy(key, k, sizeof(uint16_t));
if (*key == NORCOW_KEY_FREE) {
return secfalse;
}
}
}
*val = norcow_ptr(sector, *pos, *len);
if (*val == NULL) return secfalse;
if (*len <= NORCOW_SMALL_ITEM_SIZE) {
*pos = FLASH_ALIGN(*pos + *len);
} else {
*pos = FLASH_ALIGN(*pos + *len + NORCOW_VALID_FLAG_LEN);
}
return sectrue;
}
void norcow_delete_item(const flash_area_t *area, uint32_t len,
uint32_t val_offset) {
uint32_t end;
// Move to the beginning of the block.
if (len <= NORCOW_SMALL_ITEM_SIZE) {
// Will delete the entire small item, setting the length to 0
end = val_offset + NORCOW_SMALL_ITEM_SIZE;
val_offset -= NORCOW_LEN_LEN + NORCOW_KEY_LEN;
} else {
end = val_offset + len + NORCOW_VALID_FLAG_LEN;
}
// Delete the item head + data.
ensure(flash_unlock_write(), NULL);
flash_block_t block = {0};
while (val_offset < end) {
ensure(flash_area_write_block(area, val_offset, block), NULL);
val_offset += FLASH_BLOCK_SIZE;
}
ensure(flash_lock_write(), NULL);
}
static secbool flash_area_write_bytes(const flash_area_t *area, uint32_t offset,
uint16_t dest_len, const void *val,
uint16_t len) {
uint8_t *ptr = (uint8_t *)flash_area_get_address(area, offset, dest_len);
if (val == NULL || ptr == NULL || dest_len != len) {
return secfalse;
}
return memcmp(val, ptr, len) == 0 ? sectrue : secfalse;
}
secbool norcow_next_counter(uint16_t key, uint32_t *count) {
uint16_t len = 0;
const uint32_t *val_stored = NULL;
if (sectrue != norcow_get(key, (const void **)&val_stored, &len)) {
*count = 0;
return norcow_set_counter(key, 0);
}
if (len != sizeof(uint32_t)) {
return secfalse;
}
*count = *val_stored + 1;
if (*count < *val_stored) {
// Value overflow.
return secfalse;
}
return norcow_set_counter(key, *count);
}
/*
* Update the value of the given key. The value is updated sequentially,
* starting from position 0, caller needs to ensure that all bytes are updated
* by calling this function enough times.
*
* The new value is flashed by blocks, if the data
* passed here do not fill the block it is stored until next call in buffer.
*/
secbool norcow_update_bytes(const uint16_t key, const uint8_t *data,
const uint16_t len) {
const void *ptr = NULL;
uint16_t allocated_len = 0;
if (sectrue != find_item(norcow_write_sector, key, &ptr, &allocated_len)) {
return secfalse;
}
if (allocated_len <= NORCOW_SMALL_ITEM_SIZE) {
// small items are not updated in place
return secfalse;
}
uint32_t sector_offset =
(const uint8_t *)ptr -
(const uint8_t *)norcow_ptr(norcow_write_sector, 0, NORCOW_SECTOR_SIZE);
const flash_area_t *area = &STORAGE_AREAS[norcow_write_sector];
if (norcow_write_buffer_key != key && norcow_write_buffer_key != -1) {
// some other update bytes is in process, abort
return secfalse;
}
if (norcow_write_buffer_key == -1) {
memset(norcow_write_buffer, 0xFF, sizeof(norcow_write_buffer));
norcow_write_buffer_key = key;
norcow_write_buffer_filled = 0;
norcow_write_buffer_flashed = 0;
}
if (norcow_write_buffer_flashed + norcow_write_buffer_filled + len >
allocated_len) {
return secfalse;
}
uint16_t tmp_len = len;
uint16_t flash_offset = sector_offset + norcow_write_buffer_flashed;
ensure(flash_unlock_write(), NULL);
while (tmp_len > 0) {
uint16_t buffer_space = FLASH_BLOCK_SIZE - norcow_write_buffer_filled;
uint16_t data_to_copy = (tmp_len > buffer_space ? buffer_space : tmp_len);
memcpy(&((uint8_t *)norcow_write_buffer)[norcow_write_buffer_filled], data,
data_to_copy);
data += data_to_copy;
norcow_write_buffer_filled += data_to_copy;
tmp_len -= data_to_copy;
bool all_data_received = (norcow_write_buffer_filled +
norcow_write_buffer_flashed) == allocated_len;
bool block_full = norcow_write_buffer_filled == FLASH_BLOCK_SIZE;
if (block_full || all_data_received) {
if (!block_full) {
// all data has been received, add valid flag to last block
((uint8_t *)norcow_write_buffer)[norcow_write_buffer_filled] =
NORCOW_VALID_FLAG;
}
ensure(flash_area_write_block(area, flash_offset, norcow_write_buffer),
NULL);
flash_offset += FLASH_BLOCK_SIZE;
if (block_full && all_data_received) {
// last block of data couldn't fit the valid flag, write it in next
// block
memset(norcow_write_buffer, 0xFF, sizeof(norcow_write_buffer));
((uint8_t *)norcow_write_buffer)[0] = NORCOW_VALID_FLAG;
ensure(flash_area_write_block(area, flash_offset, norcow_write_buffer),
NULL);
flash_offset += FLASH_BLOCK_SIZE;
}
norcow_write_buffer_filled = 0;
norcow_write_buffer_flashed += FLASH_BLOCK_SIZE;
memset(norcow_write_buffer, 0xFF, sizeof(norcow_write_buffer));
if (all_data_received) {
norcow_write_buffer_key = -1;
norcow_write_buffer_flashed = 0;
}
}
}
ensure(flash_lock_write(), NULL);
return sectrue;
}