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224 lines
6.3 KiB
224 lines
6.3 KiB
/*
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* This file is part of the Trezor project, https://trezor.io/
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*
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* Copyright (c) SatoshiLabs
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU 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 program 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 General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <string.h>
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#include "common.h"
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#include "norcow.h"
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#include "storage.h"
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// Norcow storage key of configured PIN.
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#define PIN_KEY 0x0000
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// Maximum PIN length.
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#define PIN_MAXLEN 32
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// Byte-length of flash section containing fail counters.
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#define PIN_FAIL_KEY 0x0001
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#define PIN_FAIL_SECTOR_SIZE 32
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// Maximum number of failed unlock attempts.
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#define PIN_MAX_TRIES 15
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static secbool initialized = secfalse;
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static secbool unlocked = secfalse;
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static PIN_UI_WAIT_CALLBACK ui_callback = NULL;
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void storage_init(PIN_UI_WAIT_CALLBACK callback) {
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initialized = secfalse;
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unlocked = secfalse;
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norcow_init();
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initialized = sectrue;
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ui_callback = callback;
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}
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static secbool pin_fails_reset(uint16_t ofs) {
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return norcow_update(PIN_FAIL_KEY, ofs, 0);
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}
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static secbool pin_fails_increase(const uint32_t *ptr, uint16_t ofs) {
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uint32_t ctr = *ptr;
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ctr = ctr << 1;
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if (sectrue != norcow_update(PIN_FAIL_KEY, ofs, ctr)) {
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return secfalse;
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}
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uint32_t check = *ptr;
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if (ctr != check) {
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return secfalse;
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}
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return sectrue;
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}
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static void pin_fails_check_max(uint32_t ctr) {
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if (~ctr >= (1 << PIN_MAX_TRIES)) {
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norcow_wipe();
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ensure(secfalse, "pin_fails_check_max");
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}
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}
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static secbool pin_cmp(const uint32_t pin) {
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const void *spin = NULL;
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uint16_t spinlen = 0;
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norcow_get(PIN_KEY, &spin, &spinlen);
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if (NULL != spin && spinlen == sizeof(uint32_t)) {
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return sectrue * (pin == *(const uint32_t *)spin);
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} else {
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return sectrue * (1 == pin);
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}
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}
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static secbool pin_get_fails(const uint32_t **pinfail, uint32_t *pofs) {
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const void *vpinfail;
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uint16_t pinfaillen;
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unsigned int ofs;
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// The PIN_FAIL_KEY points to an area of words, initialized to
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// 0xffffffff (meaning no pin failures). The first non-zero word
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// in this area is the current pin failure counter. If PIN_FAIL_KEY
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// has no configuration or is empty, the pin failure counter is 0.
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// We rely on the fact that flash allows to clear bits and we clear one
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// bit to indicate pin failure. On success, the word is set to 0,
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// indicating that the next word is the pin failure counter.
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// Find the current pin failure counter
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if (secfalse != norcow_get(PIN_FAIL_KEY, &vpinfail, &pinfaillen)) {
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*pinfail = vpinfail;
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for (ofs = 0; ofs < pinfaillen / sizeof(uint32_t); ofs++) {
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if (((const uint32_t *)vpinfail)[ofs]) {
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*pinfail = vpinfail;
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*pofs = ofs;
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return sectrue;
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}
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}
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}
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// No pin failure section, or all entries used -> create a new one.
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uint32_t pinarea[PIN_FAIL_SECTOR_SIZE];
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memset(pinarea, 0xff, sizeof(pinarea));
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if (sectrue != norcow_set(PIN_FAIL_KEY, pinarea, sizeof(pinarea))) {
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return secfalse;
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}
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if (sectrue != norcow_get(PIN_FAIL_KEY, &vpinfail, &pinfaillen)) {
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return secfalse;
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}
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*pinfail = vpinfail;
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*pofs = 0;
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return sectrue;
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}
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secbool storage_check_pin(const uint32_t pin) {
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const uint32_t *pinfail = NULL;
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uint32_t ofs;
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uint32_t ctr;
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// Get the pin failure counter
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if (pin_get_fails(&pinfail, &ofs) != sectrue) {
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return secfalse;
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}
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// Read current failure counter
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ctr = pinfail[ofs];
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// Wipe storage if too many failures
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pin_fails_check_max(ctr);
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// Sleep for ~ctr seconds before checking the PIN.
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uint32_t progress;
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for (uint32_t wait = ~ctr; wait > 0; wait--) {
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for (int i = 0; i < 10; i++) {
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if (ui_callback) {
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if ((~ctr) > 1000000) { // precise enough
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progress = (~ctr - wait) / ((~ctr) / 1000);
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} else {
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progress = ((~ctr - wait) * 10 + i) * 100 / (~ctr);
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}
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ui_callback(wait, progress);
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}
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hal_delay(100);
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}
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}
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// Show last frame if we were waiting
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if ((~ctr > 0) && ui_callback) {
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ui_callback(0, 1000);
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}
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// First, we increase PIN fail counter in storage, even before checking the
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// PIN. If the PIN is correct, we reset the counter afterwards. If not, we
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// check if this is the last allowed attempt.
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if (sectrue != pin_fails_increase(pinfail + ofs, ofs * sizeof(uint32_t))) {
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return secfalse;
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}
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if (sectrue != pin_cmp(pin)) {
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// Wipe storage if too many failures
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pin_fails_check_max(ctr << 1);
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return secfalse;
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}
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// Finally set the counter to 0 to indicate success.
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return pin_fails_reset(ofs * sizeof(uint32_t));
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}
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secbool storage_unlock(const uint32_t pin) {
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unlocked = secfalse;
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if (sectrue == initialized && sectrue == storage_check_pin(pin)) {
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unlocked = sectrue;
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}
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return unlocked;
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}
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secbool storage_get(const uint16_t key, const void **val, uint16_t *len) {
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const uint8_t app = key >> 8;
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// APP == 0 is reserved for PIN related values
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if (sectrue != initialized || app == 0) {
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return secfalse;
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}
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// top bit of APP set indicates the value can be read from unlocked device
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if (sectrue != unlocked && ((app & 0x80) == 0)) {
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return secfalse;
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}
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return norcow_get(key, val, len);
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}
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secbool storage_set(const uint16_t key, const void *val, uint16_t len) {
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const uint8_t app = key >> 8;
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// APP == 0 is reserved for PIN related values
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if (sectrue != initialized || sectrue != unlocked || app == 0) {
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return secfalse;
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}
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return norcow_set(key, val, len);
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}
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secbool storage_has_pin(void) {
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if (sectrue != initialized) {
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return secfalse;
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}
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return sectrue == pin_cmp(1) ? secfalse : sectrue;
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}
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secbool storage_change_pin(const uint32_t oldpin, const uint32_t newpin) {
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if (sectrue != initialized || sectrue != unlocked) {
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return secfalse;
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}
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if (sectrue != storage_check_pin(oldpin)) {
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return secfalse;
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}
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return norcow_set(PIN_KEY, &newpin, sizeof(uint32_t));
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}
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void storage_wipe(void) { norcow_wipe(); }
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