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trezor-firmware/storage/norcow.c

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/*
* This file is part of the Trezor project, https://trezor.io/
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*
* 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 <string.h>
#include "common.h"
#include "flash_area.h"
#include "memzero.h"
#include "norcow.h"
#include "storage_utils.h"
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// NRC2 = 4e524332
#define NORCOW_MAGIC ((uint32_t)0x3243524e)
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// NRCW = 4e524357
#define NORCOW_MAGIC_V0 ((uint32_t)0x5743524e)
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#define NORCOW_MAGIC_LEN sizeof(uint32_t)
#define NORCOW_VERSION_LEN sizeof(uint32_t)
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// The offset from the beginning of the sector where stored items start.
#define NORCOW_STORAGE_START \
FLASH_ALIGN(NORCOW_HEADER_LEN + NORCOW_MAGIC_LEN + NORCOW_VERSION_LEN)
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// The key value which is used to indicate that the entry is not set.
#define NORCOW_KEY_FREE (0xFFFF)
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// The key value which is used to indicate that the entry has been deleted.
#define NORCOW_KEY_DELETED (0x0000)
#define NORCOW_KEY_LEN 2
#define NORCOW_LEN_LEN 2
// The index of the active reading sector and writing sector. These should be
// equal except when storage version upgrade or compaction is in progress.
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static uint8_t norcow_active_sector = 0;
static uint8_t norcow_write_sector = 0;
// The norcow version of the reading sector.
static uint32_t norcow_active_version = 0;
// The offset of the first free item in the writing sector.
static uint32_t norcow_free_offset = 0;
// Tracks how much data was already flashed in update_bytes function
static uint16_t norcow_write_buffer_flashed = 0;
static const void *norcow_ptr(uint8_t sector, uint32_t offset, uint32_t size);
static secbool find_item(uint8_t sector, uint16_t key, const void **val,
uint16_t *len);
#ifdef FLASH_BIT_ACCESS
#include "norcow_bitwise.h"
#else
#include "norcow_blockwise.h"
#endif
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/*
* Returns pointer to sector, starting with offset
* Fails when there is not enough space for data of given size
*/
static const void *norcow_ptr(uint8_t sector, uint32_t offset, uint32_t size) {
ensure(sectrue * (sector <= NORCOW_SECTOR_COUNT), "invalid sector");
return flash_area_get_address(&STORAGE_AREAS[sector], offset, size);
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}
/*
* Erases sector (and sets a magic)
*/
static void erase_sector(uint8_t sector, secbool set_magic) {
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#if NORCOW_HEADER_LEN > 0
// Backup the sector header.
uint32_t header_backup[NORCOW_HEADER_LEN / sizeof(uint32_t)] = {0};
const void *sector_start = norcow_ptr(sector, 0, NORCOW_HEADER_LEN);
memcpy(header_backup, sector_start, sizeof(header_backup));
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#endif
ensure(flash_area_erase(&STORAGE_AREAS[sector], NULL), "erase failed");
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#if NORCOW_HEADER_LEN > 0
// Copy the sector header back.
ensure(flash_unlock_write(), NULL);
for (uint32_t i = 0; i < NORCOW_HEADER_LEN / sizeof(uint32_t); ++i) {
ensure(flash_write_word(norcow_sectors[sector], i * sizeof(uint32_t),
header_backup[i]),
NULL);
}
ensure(flash_lock_write(), NULL);
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#endif
if (sectrue == set_magic) {
ensure(flash_unlock_write(), NULL);
#if FLASH_BLOCK_WORDS == 1
flash_block_t block_magic = {NORCOW_MAGIC};
ensure(flash_area_write_block(&STORAGE_AREAS[sector], NORCOW_HEADER_LEN,
block_magic),
NULL);
flash_block_t block_version = {~NORCOW_VERSION};
ensure(flash_area_write_block(&STORAGE_AREAS[sector],
NORCOW_HEADER_LEN + NORCOW_MAGIC_LEN,
block_version),
"set version failed");
#else
flash_block_t block = {NORCOW_MAGIC, ~NORCOW_VERSION};
ensure(flash_area_write_block(&STORAGE_AREAS[sector], NORCOW_HEADER_LEN,
block),
"set magic and version failed");
#endif
ensure(flash_lock_write(), NULL);
}
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}
/*
* Finds the offset from the beginning of the sector where stored items start.
*/
static secbool find_start_offset(uint8_t sector, uint32_t *offset,
uint32_t *version) {
const uint32_t *magic = norcow_ptr(sector, NORCOW_HEADER_LEN,
NORCOW_MAGIC_LEN + NORCOW_VERSION_LEN);
if (magic == NULL) {
return secfalse;
}
if (*magic == NORCOW_MAGIC) {
*offset = NORCOW_STORAGE_START;
*version = ~(magic[1]);
} else if (*magic == NORCOW_MAGIC_V0) {
*offset = NORCOW_HEADER_LEN + NORCOW_MAGIC_LEN;
*version = 0;
} else {
return secfalse;
}
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return sectrue;
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}
/*
* Finds item in given sector
*/
static secbool find_item(uint8_t sector, uint16_t key, const void **val,
uint16_t *len) {
*val = NULL;
*len = 0;
uint32_t offset = 0;
uint32_t version = 0;
if (sectrue != find_start_offset(sector, &offset, &version)) {
return secfalse;
}
for (;;) {
uint16_t k = 0, l = 0;
const void *v = NULL;
uint32_t pos = 0;
if (sectrue != read_item(sector, offset, &k, &v, &l, &pos)) {
break;
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}
if (key == k) {
*val = v;
*len = l;
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}
offset = pos;
}
return sectrue * (*val != NULL);
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}
/*
* Finds first unused offset in given sector
*/
static uint32_t find_free_offset(uint8_t sector) {
uint32_t offset = 0;
uint32_t version = 0;
if (sectrue != find_start_offset(sector, &offset, &version)) {
return secfalse;
}
for (;;) {
uint16_t key = 0, len = 0;
const void *val = NULL;
uint32_t pos = 0;
if (sectrue != read_item(sector, offset, &key, &val, &len, &pos)) {
break;
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}
offset = pos;
}
return offset;
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}
/*
* Compacts active sector and sets new active sector
*/
static void compact(void) {
uint32_t offsetr = 0;
uint32_t version = 0;
if (sectrue != find_start_offset(norcow_active_sector, &offsetr, &version)) {
return;
}
norcow_write_sector = (norcow_active_sector + 1) % NORCOW_SECTOR_COUNT;
erase_sector(norcow_write_sector, sectrue);
uint32_t offsetw = NORCOW_STORAGE_START;
for (;;) {
// read item
uint16_t k = 0, l = 0;
const void *v = NULL;
uint32_t posr = 0;
secbool r = read_item(norcow_active_sector, offsetr, &k, &v, &l, &posr);
if (sectrue != r) {
break;
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}
offsetr = posr;
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// skip deleted items
if (k == NORCOW_KEY_DELETED) {
continue;
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}
// copy the item
uint32_t posw = 0;
ensure(write_item(norcow_write_sector, offsetw, k, v, l, &posw),
"compaction write failed");
offsetw = posw;
}
erase_sector(norcow_active_sector, secfalse);
norcow_active_sector = norcow_write_sector;
norcow_active_version = NORCOW_VERSION;
norcow_free_offset = find_free_offset(norcow_write_sector);
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}
/*
* Initializes storage
*/
void norcow_init(uint32_t *norcow_version) {
secbool found = secfalse;
*norcow_version = 0;
norcow_active_sector = 0;
// detect active sector - starts with magic and has highest version
for (uint8_t i = 0; i < NORCOW_SECTOR_COUNT; i++) {
uint32_t offset = 0;
if (sectrue == find_start_offset(i, &offset, &norcow_active_version) &&
norcow_active_version >= *norcow_version) {
found = sectrue;
norcow_active_sector = i;
*norcow_version = norcow_active_version;
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}
}
// If no active sectors found or version downgrade, then erase.
if (sectrue != found || *norcow_version > NORCOW_VERSION) {
norcow_wipe();
*norcow_version = NORCOW_VERSION;
} else if (*norcow_version < NORCOW_VERSION) {
// Prepare write sector for storage upgrade.
norcow_write_sector = (norcow_active_sector + 1) % NORCOW_SECTOR_COUNT;
erase_sector(norcow_write_sector, sectrue);
norcow_free_offset = find_free_offset(norcow_write_sector);
} else {
norcow_write_sector = norcow_active_sector;
norcow_free_offset = find_free_offset(norcow_write_sector);
}
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}
/*
* Wipe the storage
*/
void norcow_wipe(void) {
// Erase the active sector first, because it contains sensitive data.
erase_sector(norcow_active_sector, sectrue);
for (uint8_t i = 0; i < NORCOW_SECTOR_COUNT; i++) {
if (i != norcow_active_sector) {
erase_sector(i, secfalse);
}
}
norcow_active_version = NORCOW_VERSION;
norcow_write_sector = norcow_active_sector;
norcow_free_offset = NORCOW_STORAGE_START;
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}
/*
* Looks for the given key, returns status of the operation
*/
secbool norcow_get(uint16_t key, const void **val, uint16_t *len) {
return find_item(norcow_active_sector, key, val, len);
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}
/*
* Reads the next entry in the storage starting at offset. Returns secfalse if
* there is none.
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*/
secbool norcow_get_next(uint32_t *offset, uint16_t *key, const void **val,
uint16_t *len) {
if (*offset == 0) {
uint32_t version = 0;
if (sectrue != find_start_offset(norcow_active_sector, offset, &version)) {
return secfalse;
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}
}
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for (;;) {
uint32_t pos = 0;
secbool ret = read_item(norcow_active_sector, *offset, key, val, len, &pos);
if (sectrue != ret) {
break;
}
*offset = pos;
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// Skip deleted items.
if (*key == NORCOW_KEY_DELETED) {
continue;
}
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if (norcow_active_version == 0) {
// Check whether the item is the latest instance.
uint32_t offsetr = *offset;
for (;;) {
uint16_t k = 0;
uint16_t l = 0;
const void *v = NULL;
ret = read_item(norcow_active_sector, offsetr, &k, &v, &l, &offsetr);
if (sectrue != ret) {
// There is no newer instance of the item.
return sectrue;
}
if (*key == k) {
// There exists a newer instance of the item.
break;
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}
}
} else {
return sectrue;
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}
}
return secfalse;
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}
/*
* Sets the given key, returns status of the operation. If NULL is passed
* as val, then norcow_set allocates a new key of size len. The value should
* then be written using norcow_update_bytes().
*/
secbool norcow_set(uint16_t key, const void *val, uint16_t len) {
secbool found = secfalse;
return norcow_set_ex(key, val, len, &found);
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}
secbool norcow_set_ex(uint16_t key, const void *val, uint16_t len,
secbool *found) {
// Key 0xffff is used as a marker to indicate that the entry is not set.
if (key == NORCOW_KEY_FREE) {
return secfalse;
}
const flash_area_t *area = &STORAGE_AREAS[norcow_write_sector];
const void *ptr = NULL;
uint16_t len_old = 0;
*found = find_item(norcow_write_sector, key, &ptr, &len_old);
uint32_t val_offset = 0;
if (sectrue == *found) {
val_offset =
(const uint8_t *)ptr -
(const uint8_t *)norcow_ptr(norcow_write_sector, 0, NORCOW_SECTOR_SIZE);
// Try to update the entry if it already exists.
if (sectrue ==
flash_area_write_bytes(area, val_offset, len_old, val, len)) {
return sectrue;
}
}
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// Delete the old item.
if (sectrue == *found) {
norcow_delete_item(area, len_old, val_offset);
}
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// Check whether there is enough free space and compact if full.
if (norcow_free_offset + FLASH_ALIGN(NORCOW_MAX_PREFIX_LEN + len) >
NORCOW_SECTOR_SIZE) {
compact();
}
// Write new item.
uint32_t pos = 0;
if (sectrue != write_item(norcow_write_sector, norcow_free_offset, key, val,
len, &pos)) {
return secfalse;
}
norcow_free_offset = pos;
return sectrue;
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}
/*
* Deletes the given key, returns status of the operation.
*/
secbool norcow_delete(uint16_t key) {
// Key 0xffff is used as a marker to indicate that the entry is not set.
if (key == NORCOW_KEY_FREE) {
return secfalse;
}
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const flash_area_t *area = &STORAGE_AREAS[norcow_write_sector];
const void *ptr = NULL;
uint16_t len = 0;
if (sectrue != find_item(norcow_write_sector, key, &ptr, &len)) {
return secfalse;
}
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uint32_t val_offset =
(const uint8_t *)ptr -
(const uint8_t *)norcow_ptr(norcow_write_sector, 0, NORCOW_SECTOR_SIZE);
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norcow_delete_item(area, len, val_offset);
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return sectrue;
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}
secbool norcow_set_counter(uint16_t key, uint32_t count) {
// The count is stored as a 32-bit integer followed by a tail of "1" bits,
// which is used as a tally.
uint32_t value[1 + COUNTER_TAIL_WORDS] = {0};
value[0] = count;
memset(&value[1], 0xff, sizeof(value) - sizeof(value[0]));
return norcow_set(key, value, sizeof(value));
}
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/*
* Complete storage version upgrade
*/
secbool norcow_upgrade_finish(void) {
erase_sector(norcow_active_sector, secfalse);
norcow_active_sector = norcow_write_sector;
norcow_active_version = NORCOW_VERSION;
return sectrue;
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}