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norcow.c
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norcow.c
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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 <string.h>
#include "common.h"
#include "flash.h"
#include "norcow.h"
// NRC2 = 4e524332
#define NORCOW_MAGIC ((uint32_t)0x3243524e)
// NRCW = 4e524357
#define NORCOW_MAGIC_V0 ((uint32_t)0x5743524e)
#define NORCOW_WORD_SIZE (sizeof(uint32_t))
#define NORCOW_PREFIX_LEN NORCOW_WORD_SIZE
#define NORCOW_MAGIC_LEN NORCOW_WORD_SIZE
#define NORCOW_VERSION_LEN NORCOW_WORD_SIZE
// The key value which is used to indicate that the entry is not set.
#define NORCOW_KEY_FREE (0xFFFF)
// The key value which is used to indicate that the entry has been deleted.
#define NORCOW_KEY_DELETED (0x0000)
// The offset from the beginning of the sector where stored items start.
#define NORCOW_STORAGE_START \
(NORCOW_HEADER_LEN + NORCOW_MAGIC_LEN + NORCOW_VERSION_LEN)
// Map from sector index to sector number.
static const uint8_t norcow_sectors[NORCOW_SECTOR_COUNT] = NORCOW_SECTORS;
// The index of the active reading sector and writing sector. These should be
// equal except when storage version upgrade or compaction is in progress.
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;
/*
* 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_get_address(norcow_sectors[sector], offset, size);
}
/*
* Writes data to given sector, starting from offset
*/
static secbool norcow_write(uint8_t sector, uint32_t offset, uint32_t prefix,
const uint8_t *data, uint16_t len) {
if (sector >= NORCOW_SECTOR_COUNT) {
return secfalse;
}
if (offset + NORCOW_PREFIX_LEN + len > NORCOW_SECTOR_SIZE) {
return secfalse;
}
ensure(flash_unlock_write(), NULL);
// write prefix
ensure(flash_write_word(norcow_sectors[sector], offset, prefix), NULL);
offset += NORCOW_PREFIX_LEN;
if (data != NULL) {
// write data
for (uint16_t i = 0; i < len; i++, offset++) {
ensure(flash_write_byte(norcow_sectors[sector], offset, data[i]), NULL);
}
} else {
offset += len;
}
// pad with zeroes
for (; offset % NORCOW_WORD_SIZE; offset++) {
ensure(flash_write_byte(norcow_sectors[sector], offset, 0x00), NULL);
}
ensure(flash_lock_write(), NULL);
return sectrue;
}
/*
* Erases sector (and sets a magic)
*/
static void erase_sector(uint8_t sector, secbool set_magic) {
#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));
#endif
ensure(flash_erase(norcow_sectors[sector]), "erase failed");
#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);
#endif
if (sectrue == set_magic) {
ensure(norcow_write(sector, NORCOW_HEADER_LEN, NORCOW_MAGIC, NULL, 0),
"set magic failed");
ensure(norcow_write(sector, NORCOW_HEADER_LEN + NORCOW_MAGIC_LEN,
~NORCOW_VERSION, NULL, 0),
"set version failed");
}
}
#define ALIGN4(X) (X) = ((X) + 3) & ~3
/*
* 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, 2);
if (k == NULL) return secfalse;
*pos += 2;
memcpy(key, k, sizeof(uint16_t));
if (*key == NORCOW_KEY_FREE) {
return secfalse;
}
const void *l = norcow_ptr(sector, *pos, 2);
if (l == NULL) return secfalse;
*pos += 2;
memcpy(len, l, sizeof(uint16_t));
*val = norcow_ptr(sector, *pos, *len);
if (*val == NULL) return secfalse;
*pos += *len;
ALIGN4(*pos);
return sectrue;
}
/*
* Writes one item starting from offset
*/
static secbool write_item(uint8_t sector, uint32_t offset, uint16_t key,
const void *val, uint16_t len, uint32_t *pos) {
uint32_t prefix = ((uint32_t)len << 16) | key;
*pos = offset + NORCOW_PREFIX_LEN + len;
ALIGN4(*pos);
return norcow_write(sector, offset, prefix, val, len);
}
/*
* 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;
}
return sectrue;
}
/*
* 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;
}
if (key == k) {
*val = v;
*len = l;
}
offset = pos;
}
return sectrue * (*val != NULL);
}
/*
* 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;
}
offset = pos;
}
return offset;
}
/*
* 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;
}
offsetr = posr;
// skip deleted items
if (k == NORCOW_KEY_DELETED) {
continue;
}
// 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);
}
/*
* 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;
}
}
// 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);
}
}
/*
* 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;
}
/*
* 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);
}
/*
* Reads the next entry in the storage starting at offset. Returns secfalse if
* there is none.
*/
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;
}
}
for (;;) {
uint32_t pos = 0;
secbool ret = read_item(norcow_active_sector, *offset, key, val, len, &pos);
if (sectrue != ret) {
break;
}
*offset = pos;
// Skip deleted items.
if (*key == NORCOW_KEY_DELETED) {
continue;
}
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;
}
}
} else {
return sectrue;
}
}
return secfalse;
}
/*
* 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);
}
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 uint8_t sector_num = norcow_sectors[norcow_write_sector];
secbool ret = secfalse;
const void *ptr = NULL;
uint16_t len_old = 0;
*found = find_item(norcow_write_sector, key, &ptr, &len_old);
// Try to update the entry if it already exists.
uint32_t offset = 0;
if (sectrue == *found) {
offset =
(const uint8_t *)ptr -
(const uint8_t *)norcow_ptr(norcow_write_sector, 0, NORCOW_SECTOR_SIZE);
if (val != NULL && len_old == len) {
ret = sectrue;
ensure(flash_unlock_write(), NULL);
for (uint16_t i = 0; i < len; i++) {
if (sectrue != flash_write_byte(sector_num, offset + i,
((const uint8_t *)val)[i])) {
ret = secfalse;
break;
}
}
ensure(flash_lock_write(), NULL);
}
}
// If the update was not possible then write the entry as a new item.
if (secfalse == ret) {
// Delete the old item.
if (sectrue == *found) {
ensure(flash_unlock_write(), NULL);
// Update the prefix to indicate that the old item has been deleted.
uint32_t prefix = (uint32_t)len_old << 16;
ensure(flash_write_word(sector_num, offset - NORCOW_PREFIX_LEN, prefix),
NULL);
// Delete the old item data.
uint32_t end = offset + len_old;
while (offset < end) {
ensure(flash_write_word(sector_num, offset, 0x00000000), NULL);
offset += NORCOW_WORD_SIZE;
}
ensure(flash_lock_write(), NULL);
}
// Check whether there is enough free space and compact if full.
if (norcow_free_offset + NORCOW_PREFIX_LEN + len > NORCOW_SECTOR_SIZE) {
compact();
}
// Write new item.
uint32_t pos = 0;
ret = write_item(norcow_write_sector, norcow_free_offset, key, val, len,
&pos);
if (sectrue == ret) {
norcow_free_offset = pos;
}
}
return ret;
}
/*
* 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;
}
const uint8_t sector_num = norcow_sectors[norcow_write_sector];
const void *ptr = NULL;
uint16_t len = 0;
if (sectrue != find_item(norcow_write_sector, key, &ptr, &len)) {
return secfalse;
}
uint32_t offset =
(const uint8_t *)ptr -
(const uint8_t *)norcow_ptr(norcow_write_sector, 0, NORCOW_SECTOR_SIZE);
ensure(flash_unlock_write(), NULL);
// Update the prefix to indicate that the item has been deleted.
uint32_t prefix = (uint32_t)len << 16;
ensure(flash_write_word(sector_num, offset - NORCOW_PREFIX_LEN, prefix),
NULL);
// Delete the item data.
uint32_t end = offset + len;
while (offset < end) {
ensure(flash_write_word(sector_num, offset, 0x00000000), NULL);
offset += NORCOW_WORD_SIZE;
}
ensure(flash_lock_write(), NULL);
return sectrue;
}
/*
* Update a word in flash at the given pointer. The pointer must point
* into the NORCOW area.
*/
secbool norcow_update_word(uint16_t key, uint16_t offset, uint32_t value) {
const void *ptr = NULL;
uint16_t len = 0;
if (sectrue != find_item(norcow_write_sector, key, &ptr, &len)) {
return secfalse;
}
if ((offset & 3) != 0 || offset >= len) {
return secfalse;
}
uint32_t sector_offset =
(const uint8_t *)ptr -
(const uint8_t *)norcow_ptr(norcow_write_sector, 0, NORCOW_SECTOR_SIZE) +
offset;
ensure(flash_unlock_write(), NULL);
ensure(flash_write_word(norcow_sectors[norcow_write_sector], sector_offset,
value),
NULL);
ensure(flash_lock_write(), NULL);
return sectrue;
}
/*
* Update the value of the given key starting at the given offset.
*/
secbool norcow_update_bytes(const uint16_t key, const uint16_t offset,
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 (offset + len > allocated_len) {
return secfalse;
}
uint32_t sector_offset =
(const uint8_t *)ptr -
(const uint8_t *)norcow_ptr(norcow_write_sector, 0, NORCOW_SECTOR_SIZE) +
offset;
uint8_t sector = norcow_sectors[norcow_write_sector];
ensure(flash_unlock_write(), NULL);
for (uint16_t i = 0; i < len; i++, sector_offset++) {
ensure(flash_write_byte(sector, sector_offset, data[i]), NULL);
}
ensure(flash_lock_write(), NULL);
return sectrue;
}
/*
* 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;
}