mirror of
https://github.com/trezor/trezor-firmware.git
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c4e8bd0d0e
Clear storage marker first before clearing the second sector to prevent leaving a state where only PIN failures have been cleared but storage is still present.
562 lines
15 KiB
C
562 lines
15 KiB
C
/*
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* This file is part of the TREZOR project.
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*
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* Copyright (C) 2014 Pavol Rusnak <stick@satoshilabs.com>
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*
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* This library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <string.h>
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#include <stdint.h>
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#include <libopencm3/stm32/flash.h>
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#include "messages.pb.h"
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#include "storage.pb.h"
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#include "trezor.h"
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#include "sha2.h"
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#include "aes.h"
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#include "pbkdf2.h"
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#include "bip32.h"
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#include "bip39.h"
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#include "curves.h"
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#include "util.h"
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#include "memory.h"
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#include "rng.h"
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#include "storage.h"
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#include "debug.h"
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#include "protect.h"
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#include "layout2.h"
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Storage storage;
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uint8_t storage_uuid[12];
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char storage_uuid_str[25];
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/*
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storage layout:
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offset | type/length | description
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--------+--------------+-------------------------------
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0x0000 | 4 bytes | magic = 'stor'
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0x0004 | 12 bytes | uuid
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0x0010 | ? bytes | Storage structure
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--------+--------------+-------------------------------
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0x4000 | 4 kbytes | area for pin failures
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0x5000 | 256 bytes | area for u2f counter updates
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0x5100 | 11.75 kbytes | reserved
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The area for pin failures looks like this:
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0 ... 0 pinfail 0xffffffff .. 0xffffffff
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The pinfail is a binary number of the form 1...10...0,
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the number of zeros is the number of pin failures.
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This layout is used because we can only clear bits without
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erasing the flash.
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The area for u2f counter updates is just a sequence of zero-bits
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followed by a sequence of one-bits. The bits in a byte are numbered
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from LSB to MSB. The number of zero bits is the offset that should
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be added to the storage u2f_counter to get the real counter value.
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*/
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#define FLASH_STORAGE_PINAREA (FLASH_META_START + 0x4000)
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#define FLASH_STORAGE_PINAREA_LEN (0x1000)
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#define FLASH_STORAGE_U2FAREA (FLASH_STORAGE_PINAREA + FLASH_STORAGE_PINAREA_LEN)
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#define FLASH_STORAGE_U2FAREA_LEN (0x100)
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#define FLASH_STORAGE_REALLEN (4 + sizeof(storage_uuid) + sizeof(Storage))
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_Static_assert(FLASH_STORAGE_START + FLASH_STORAGE_REALLEN <= FLASH_STORAGE_PINAREA, "Storage struct is too large for TREZOR flash");
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_Static_assert((sizeof(storage_uuid) & 3) == 0, "storage uuid unaligned");
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_Static_assert((sizeof(storage) & 3) == 0, "storage unaligned");
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/* Current u2f offset, i.e. u2f counter is
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* storage.u2f_counter + storage_u2f_offset.
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* This corresponds to the number of cleared bits in the U2FAREA.
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*/
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static uint32_t storage_u2f_offset;
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static bool sessionSeedCached, sessionSeedUsesPassphrase;
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static uint8_t sessionSeed[64];
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static bool sessionPinCached;
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static bool sessionPassphraseCached;
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static char sessionPassphrase[51];
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#define STORAGE_VERSION 6
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void storage_show_error(void)
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{
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layoutDialog(DIALOG_ICON_ERROR, NULL, NULL, NULL, "Storage failure", "detected.", NULL, "Please unplug", "the device.", NULL);
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for (;;) { }
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}
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void storage_check_flash_errors(void)
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{
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// flash operation failed
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if (FLASH_SR & (FLASH_SR_PGAERR | FLASH_SR_PGPERR | FLASH_SR_PGSERR | FLASH_SR_WRPERR)) {
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storage_show_error();
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}
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}
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bool storage_from_flash(void)
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{
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if (memcmp((void *)FLASH_STORAGE_START, "stor", 4) != 0) {
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// wrong magic
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return false;
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}
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uint32_t version = ((Storage *)(FLASH_STORAGE_START + 4 + sizeof(storage_uuid)))->version;
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// version 1: since 1.0.0
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// version 2: since 1.2.1
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// version 3: since 1.3.1
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// version 4: since 1.3.2
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// version 5: since 1.3.3
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// version 6: since 1.3.6
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if (version > STORAGE_VERSION) {
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// downgrade -> clear storage
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return false;
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}
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// load uuid
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memcpy(storage_uuid, (void *)(FLASH_STORAGE_START + 4), sizeof(storage_uuid));
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data2hex(storage_uuid, sizeof(storage_uuid), storage_uuid_str);
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// copy storage
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memcpy(&storage, (void *)(FLASH_STORAGE_START + 4 + sizeof(storage_uuid)), sizeof(Storage));
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if (version <= 5) {
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// convert PIN failure counter from version 5 format
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uint32_t pinctr = storage.has_pin_failed_attempts
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? storage.pin_failed_attempts : 0;
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if (pinctr > 31)
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pinctr = 31;
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flash_clear_status_flags();
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flash_unlock();
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// erase extra storage sector
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flash_erase_sector(FLASH_META_SECTOR_LAST, FLASH_CR_PROGRAM_X32);
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flash_program_word(FLASH_STORAGE_PINAREA, 0xffffffff << pinctr);
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flash_lock();
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storage_check_flash_errors();
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storage.has_pin_failed_attempts = false;
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storage.pin_failed_attempts = 0;
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}
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uint32_t *u2fptr = (uint32_t*) FLASH_STORAGE_U2FAREA;
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while (*u2fptr == 0)
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u2fptr++;
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storage_u2f_offset = 32 * (u2fptr - (uint32_t*) FLASH_STORAGE_U2FAREA);
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uint32_t u2fword = *u2fptr;
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while ((u2fword & 1) == 0) {
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storage_u2f_offset++;
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u2fword >>= 1;
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}
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// upgrade storage version
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if (version != STORAGE_VERSION) {
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storage.version = STORAGE_VERSION;
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storage_commit();
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}
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return true;
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}
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void storage_init(void)
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{
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if (!storage_from_flash()) {
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storage_reset();
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storage_reset_uuid();
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storage_commit();
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storage_clearPinArea();
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}
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}
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void storage_reset_uuid(void)
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{
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// set random uuid
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random_buffer(storage_uuid, sizeof(storage_uuid));
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data2hex(storage_uuid, sizeof(storage_uuid), storage_uuid_str);
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}
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void storage_reset(void)
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{
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// reset storage struct
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memset(&storage, 0, sizeof(storage));
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storage.version = STORAGE_VERSION;
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session_clear(true); // clear PIN as well
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}
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void session_clear(bool clear_pin)
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{
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sessionSeedCached = false;
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memset(&sessionSeed, 0, sizeof(sessionSeed));
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sessionPassphraseCached = false;
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memset(&sessionPassphrase, 0, sizeof(sessionPassphrase));
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if (clear_pin) {
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sessionPinCached = false;
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}
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}
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static uint32_t storage_flash_words(uint32_t addr, uint32_t *src, int nwords) {
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int i;
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for (i = 0; i < nwords; i++) {
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flash_program_word(addr, *src++);
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addr += 4;
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}
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return addr;
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}
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static void storage_commit_locked(void)
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{
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uint8_t meta_backup[FLASH_META_DESC_LEN];
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// backup meta
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memcpy(meta_backup, (uint8_t*)FLASH_META_START, FLASH_META_DESC_LEN);
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// erase storage
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flash_erase_sector(FLASH_META_SECTOR_FIRST, FLASH_CR_PROGRAM_X32);
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// copy meta
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uint32_t flash = FLASH_META_START;
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flash = storage_flash_words(flash, (uint32_t *)meta_backup, FLASH_META_DESC_LEN/4);
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// copy storage
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flash_program_word(flash, *(uint32_t *) "stor");
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flash += 4;
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flash = storage_flash_words(flash, (uint32_t *)&storage_uuid, sizeof(storage_uuid)/4);
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flash = storage_flash_words(flash, (uint32_t *)&storage, sizeof(storage)/4);
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// fill remainder with zero for future extensions
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while (flash < FLASH_STORAGE_PINAREA) {
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flash_program_word(flash, 0);
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flash += 4;
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}
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}
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void storage_commit(void)
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{
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flash_clear_status_flags();
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flash_unlock();
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storage_commit_locked();
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flash_lock();
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storage_check_flash_errors();
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}
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void storage_loadDevice(LoadDevice *msg)
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{
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storage_reset();
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storage.has_imported = true;
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storage.imported = true;
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if (msg->has_pin > 0) {
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storage_setPin(msg->pin);
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}
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if (msg->has_passphrase_protection) {
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storage.has_passphrase_protection = true;
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storage.passphrase_protection = msg->passphrase_protection;
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} else {
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storage.has_passphrase_protection = false;
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}
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if (msg->has_node) {
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storage.has_node = true;
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storage.has_mnemonic = false;
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memcpy(&storage.node, &(msg->node), sizeof(HDNodeType));
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sessionSeedCached = false;
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memset(&sessionSeed, 0, sizeof(sessionSeed));
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} else if (msg->has_mnemonic) {
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storage.has_mnemonic = true;
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storage.has_node = false;
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strlcpy(storage.mnemonic, msg->mnemonic, sizeof(storage.mnemonic));
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sessionSeedCached = false;
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memset(&sessionSeed, 0, sizeof(sessionSeed));
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}
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if (msg->has_language) {
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storage_setLanguage(msg->language);
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}
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if (msg->has_label) {
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storage_setLabel(msg->label);
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}
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}
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void storage_setLabel(const char *label)
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{
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if (!label) return;
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storage.has_label = true;
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strlcpy(storage.label, label, sizeof(storage.label));
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}
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void storage_setLanguage(const char *lang)
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{
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if (!lang) return;
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// sanity check
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if (strcmp(lang, "english") == 0) {
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storage.has_language = true;
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strlcpy(storage.language, lang, sizeof(storage.language));
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}
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}
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void storage_setPassphraseProtection(bool passphrase_protection)
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{
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sessionSeedCached = false;
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sessionPassphraseCached = false;
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storage.has_passphrase_protection = true;
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storage.passphrase_protection = passphrase_protection;
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}
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void storage_setHomescreen(const uint8_t *data, uint32_t size)
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{
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if (data && size == 1024) {
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storage.has_homescreen = true;
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memcpy(storage.homescreen.bytes, data, size);
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storage.homescreen.size = size;
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} else {
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storage.has_homescreen = false;
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memset(storage.homescreen.bytes, 0, sizeof(storage.homescreen.bytes));
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storage.homescreen.size = 0;
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}
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}
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void get_root_node_callback(uint32_t iter, uint32_t total)
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{
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layoutProgress("Waking up", 1000 * iter / total);
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}
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const uint8_t *storage_getSeed(bool usePassphrase)
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{
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// root node is properly cached
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if (usePassphrase == sessionSeedUsesPassphrase
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&& sessionSeedCached) {
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return sessionSeed;
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}
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// if storage has mnemonic, convert it to node and use it
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if (storage.has_mnemonic) {
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if (usePassphrase && !protectPassphrase()) {
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return NULL;
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}
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mnemonic_to_seed(storage.mnemonic, usePassphrase ? sessionPassphrase : "", sessionSeed, get_root_node_callback); // BIP-0039
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sessionSeedCached = true;
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sessionSeedUsesPassphrase = usePassphrase;
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return sessionSeed;
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}
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return NULL;
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}
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bool storage_getRootNode(HDNode *node, const char *curve, bool usePassphrase)
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{
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// if storage has node, decrypt and use it
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if (storage.has_node && strcmp(curve, SECP256K1_NAME) == 0) {
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if (!protectPassphrase()) {
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return false;
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}
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if (hdnode_from_xprv(storage.node.depth, storage.node.fingerprint, storage.node.child_num, storage.node.chain_code.bytes, storage.node.private_key.bytes, curve, node) == 0) {
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return false;
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}
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if (storage.has_passphrase_protection && storage.passphrase_protection && sessionPassphraseCached && strlen(sessionPassphrase) > 0) {
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// decrypt hd node
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uint8_t secret[64];
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PBKDF2_HMAC_SHA512_CTX pctx;
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pbkdf2_hmac_sha512_Init(&pctx, (const uint8_t *)sessionPassphrase, strlen(sessionPassphrase), (const uint8_t *)"TREZORHD", 8);
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get_root_node_callback(0, BIP39_PBKDF2_ROUNDS);
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for (int i = 0; i < 8; i++) {
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pbkdf2_hmac_sha512_Update(&pctx, BIP39_PBKDF2_ROUNDS / 8);
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get_root_node_callback((i + 1) * BIP39_PBKDF2_ROUNDS / 8, BIP39_PBKDF2_ROUNDS);
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}
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pbkdf2_hmac_sha512_Final(&pctx, secret);
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aes_decrypt_ctx ctx;
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aes_decrypt_key256(secret, &ctx);
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aes_cbc_decrypt(node->chain_code, node->chain_code, 32, secret + 32, &ctx);
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aes_cbc_decrypt(node->private_key, node->private_key, 32, secret + 32, &ctx);
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}
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return true;
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}
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const uint8_t *seed = storage_getSeed(usePassphrase);
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if (seed == NULL) {
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return false;
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}
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return hdnode_from_seed(seed, 64, curve, node);
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}
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const char *storage_getLabel(void)
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{
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return storage.has_label ? storage.label : 0;
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}
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const char *storage_getLanguage(void)
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{
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return storage.has_language ? storage.language : 0;
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}
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const uint8_t *storage_getHomescreen(void)
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{
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return (storage.has_homescreen && storage.homescreen.size == 1024) ? storage.homescreen.bytes : 0;
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}
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/* Check whether pin matches storage. The pin must be a null-terminated
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* string with at most 9 characters.
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*/
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bool storage_isPinCorrect(const char *pin)
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{
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/* The execution time of the following code only depends on the
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* (public) input. This avoids timing attacks.
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*/
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char diff = 0;
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uint32_t i = 0;
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while (pin[i]) {
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diff |= storage.pin[i] - pin[i];
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i++;
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}
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diff |= storage.pin[i];
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return diff == 0;
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}
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bool storage_hasPin(void)
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{
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return storage.has_pin && storage.pin[0] != 0;
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}
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void storage_setPin(const char *pin)
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{
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if (pin && pin[0]) {
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storage.has_pin = true;
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strlcpy(storage.pin, pin, sizeof(storage.pin));
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} else {
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storage.has_pin = false;
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storage.pin[0] = 0;
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}
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storage_commit();
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sessionPinCached = false;
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}
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void session_cachePassphrase(const char *passphrase)
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{
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strlcpy(sessionPassphrase, passphrase, sizeof(sessionPassphrase));
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sessionPassphraseCached = true;
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}
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bool session_isPassphraseCached(void)
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{
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return sessionPassphraseCached;
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}
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void session_cachePin(void)
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{
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sessionPinCached = true;
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}
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bool session_isPinCached(void)
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{
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return sessionPinCached;
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}
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void storage_clearPinArea(void)
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{
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flash_clear_status_flags();
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flash_unlock();
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flash_erase_sector(FLASH_META_SECTOR_LAST, FLASH_CR_PROGRAM_X32);
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flash_lock();
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storage_check_flash_errors();
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storage_u2f_offset = 0;
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}
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// called when u2f area or pin area overflows
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static void storage_area_recycle(uint32_t new_pinfails)
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{
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// first clear storage marker. In case of a failure below it is better
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// to clear the storage than to allow restarting with zero PIN failures
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flash_program_word(FLASH_STORAGE_START, 0);
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if (*(uint32_t *)FLASH_STORAGE_START != 0) {
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storage_show_error();
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}
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// erase storage sector
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flash_erase_sector(FLASH_META_SECTOR_LAST, FLASH_CR_PROGRAM_X32);
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flash_program_word(FLASH_STORAGE_PINAREA, new_pinfails);
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if (*(uint32_t *)FLASH_STORAGE_PINAREA != new_pinfails) {
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storage_show_error();
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}
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if (storage_u2f_offset > 0) {
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storage.has_u2f_counter = true;
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storage.u2f_counter += storage_u2f_offset;
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storage_u2f_offset = 0;
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}
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storage_commit_locked();
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}
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void storage_resetPinFails(uint32_t *pinfailsptr)
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{
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flash_clear_status_flags();
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flash_unlock();
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if ((uint32_t) (pinfailsptr + 1)
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>= FLASH_STORAGE_PINAREA + FLASH_STORAGE_PINAREA_LEN) {
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// recycle extra storage sector
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storage_area_recycle(0xffffffff);
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} else {
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flash_program_word((uint32_t) pinfailsptr, 0);
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}
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flash_lock();
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storage_check_flash_errors();
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}
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|
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bool storage_increasePinFails(uint32_t *pinfailsptr)
|
|
{
|
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uint32_t newctr = *pinfailsptr << 1;
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// counter already at maximum, we do not increase it any more
|
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// return success so that a good pin is accepted
|
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if (!newctr)
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return true;
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|
|
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flash_clear_status_flags();
|
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flash_unlock();
|
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flash_program_word((uint32_t) pinfailsptr, newctr);
|
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flash_lock();
|
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storage_check_flash_errors();
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|
|
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return *pinfailsptr == newctr;
|
|
}
|
|
|
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uint32_t *storage_getPinFailsPtr(void)
|
|
{
|
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uint32_t *pinfailsptr = (uint32_t *) FLASH_STORAGE_PINAREA;
|
|
while (*pinfailsptr == 0)
|
|
pinfailsptr++;
|
|
return pinfailsptr;
|
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}
|
|
|
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bool storage_isInitialized(void)
|
|
{
|
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return storage.has_node || storage.has_mnemonic;
|
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}
|
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|
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uint32_t storage_nextU2FCounter(void)
|
|
{
|
|
uint32_t *ptr = ((uint32_t *) FLASH_STORAGE_U2FAREA) + (storage_u2f_offset / 32);
|
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uint32_t newval = 0xfffffffe << (storage_u2f_offset & 31);
|
|
|
|
flash_clear_status_flags();
|
|
flash_unlock();
|
|
flash_program_word((uint32_t) ptr, newval);
|
|
storage_u2f_offset++;
|
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if (storage_u2f_offset >= 8 * FLASH_STORAGE_U2FAREA_LEN) {
|
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storage_area_recycle(*storage_getPinFailsPtr());
|
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}
|
|
flash_lock();
|
|
storage_check_flash_errors();
|
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return storage.u2f_counter + storage_u2f_offset;
|
|
}
|