Don't reflash storage after each PIN entry
Instead of reflashing the whole storage, we use a designated area in the second storage block, where we mark each PIN failure by a single zero bit. This is because one can set bits in flash to zero but not to one. If the PIN was entered successfully the whole word is set to zero and the next word stores the new PIN failure counter.
This commit is contained in:
Jochen Hoenicke
parent
e0539f8f8b
commit
da98a3a6fd
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@ -142,31 +142,29 @@ const char *requestPin(PinMatrixRequestType type, const char *text)
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bool protectPin(bool use_cached)
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{
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if (!storage.has_pin || strlen(storage.pin) == 0 || (use_cached && session_isPinCached())) {
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if (!storage.has_pin || storage.pin[0] == 0 || (use_cached && session_isPinCached())) {
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return true;
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}
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uint32_t fails = storage_getPinFails();
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if (fails) {
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uint32_t wait;
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wait = (fails < 32) ? (1u << fails) : 0xFFFFFFFF;
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while (--wait > 0) {
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// convert wait to secstr string
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char secstrbuf[20];
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strlcpy(secstrbuf, "________0 seconds", sizeof(secstrbuf));
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char *secstr = secstrbuf + 9;
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uint32_t secs = wait;
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while (secs > 0 && secstr >= secstrbuf) {
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secstr--;
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*secstr = (secs % 10) + '0';
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secs /= 10;
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}
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if (wait == 1) {
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secstrbuf[16] = 0;
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}
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layoutDialog(DIALOG_ICON_INFO, NULL, NULL, NULL, "Wrong PIN entered", NULL, "Please wait", secstr, "to continue ...", NULL);
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// wait one second
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usbDelay(840000);
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uint32_t *fails = storage_getPinFailsPtr();
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uint32_t wait = ~*fails;
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while (wait > 0) {
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// convert wait to secstr string
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char secstrbuf[20];
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strlcpy(secstrbuf, "________0 seconds", sizeof(secstrbuf));
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char *secstr = secstrbuf + 9;
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uint32_t secs = wait;
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while (secs > 0 && secstr >= secstrbuf) {
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secstr--;
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*secstr = (secs % 10) + '0';
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secs /= 10;
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}
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if (wait == 1) {
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secstrbuf[16] = 0;
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}
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layoutDialog(DIALOG_ICON_INFO, NULL, NULL, NULL, "Wrong PIN entered", NULL, "Please wait", secstr, "to continue ...", NULL);
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// wait one second
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usbDelay(840000);
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wait--;
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}
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const char *pin;
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pin = requestPin(PinMatrixRequestType_PinMatrixRequestType_Current, "Please enter current PIN:");
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@ -174,11 +172,9 @@ bool protectPin(bool use_cached)
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fsm_sendFailure(FailureType_Failure_PinCancelled, "PIN Cancelled");
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return false;
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}
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storage_increasePinFails();
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bool increase_failed = (fails >= storage_getPinFails());
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if (storage_isPinCorrect(pin) && !increase_failed) {
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if (storage_increasePinFails(fails) && storage_isPinCorrect(pin)) {
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session_cachePin();
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storage_resetPinFails();
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storage_resetPinFails(fails);
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return true;
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} else {
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fsm_sendFailure(FailureType_Failure_PinInvalid, "Invalid PIN");
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@ -40,13 +40,38 @@
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#include "protect.h"
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#include "layout2.h"
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_Static_assert(sizeof(Storage) <= FLASH_STORAGE_LEN, "Storage struct is too large for TREZOR flash");
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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 | ? | Storage structure
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0x4000 | 4 kbytes | area for pin failures
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0x5000 | 12 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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*/
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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_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 bool sessionSeedCached;
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static uint8_t sessionSeed[64];
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static bool sessionPinCached;
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@ -54,36 +79,41 @@ static bool sessionPinCached;
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static bool sessionPassphraseCached;
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static char sessionPassphrase[51];
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/*
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storage layout:
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#define STORAGE_VERSION 6
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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 | ? | Storage structure
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*/
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#define STORAGE_VERSION 5
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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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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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}
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void storage_from_flash(uint32_t version)
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{
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switch (version) {
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case 1: // copy (since 1.0.0)
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memcpy(&storage, (void *)(FLASH_STORAGE_START + 4 + sizeof(storage_uuid)), sizeof(Storage));
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break;
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case 2: // copy (since 1.2.1)
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memcpy(&storage, (void *)(FLASH_STORAGE_START + 4 + sizeof(storage_uuid)), sizeof(Storage));
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break;
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case 3: // copy (since 1.3.1)
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memcpy(&storage, (void *)(FLASH_STORAGE_START + 4 + sizeof(storage_uuid)), sizeof(Storage));
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break;
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case 4: // copy (since 1.3.2)
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memcpy(&storage, (void *)(FLASH_STORAGE_START + 4 + sizeof(storage_uuid)), sizeof(Storage));
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break;
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case 5: // copy (since 1.3.3)
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memcpy(&storage, (void *)(FLASH_STORAGE_START + 4 + sizeof(storage_uuid)), sizeof(Storage));
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break;
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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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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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storage.version = STORAGE_VERSION;
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}
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@ -136,35 +166,29 @@ void session_clear(bool clear_pin)
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}
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}
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static uint8_t meta_backup[FLASH_META_LEN];
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void storage_commit(void)
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{
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int i;
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uint32_t *w;
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uint32_t meta_backup[(FLASH_STORAGE_PINAREA - FLASH_META_START) / 4];
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// backup meta
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memcpy(meta_backup, (void *)FLASH_META_START, FLASH_META_LEN);
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memcpy((uint8_t*)meta_backup, (uint8_t*)FLASH_META_START, FLASH_META_DESC_LEN);
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// modify storage
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memcpy((uint8_t*)meta_backup + FLASH_META_DESC_LEN, "stor", 4);
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memcpy((uint8_t*)meta_backup + FLASH_META_DESC_LEN + 4, storage_uuid, sizeof(storage_uuid));
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memcpy((uint8_t*)meta_backup + FLASH_META_DESC_LEN + 4 + sizeof(storage_uuid), &storage, sizeof(Storage));
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memset((uint8_t*)meta_backup + FLASH_META_DESC_LEN + FLASH_STORAGE_REALLEN, 0, sizeof(meta_backup) - FLASH_META_DESC_LEN - FLASH_STORAGE_REALLEN);
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flash_clear_status_flags();
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flash_unlock();
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// erase storage
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for (i = FLASH_META_SECTOR_FIRST; i <= FLASH_META_SECTOR_LAST; i++) {
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flash_erase_sector(i, FLASH_CR_PROGRAM_X32);
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}
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// modify storage
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memcpy(meta_backup + FLASH_META_DESC_LEN, "stor", 4);
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memcpy(meta_backup + FLASH_META_DESC_LEN + 4, storage_uuid, sizeof(storage_uuid));
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memcpy(meta_backup + FLASH_META_DESC_LEN + 4 + sizeof(storage_uuid), &storage, sizeof(Storage));
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flash_erase_sector(FLASH_META_SECTOR_FIRST, FLASH_CR_PROGRAM_X32);
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// copy it back
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for (i = 0; i < FLASH_META_LEN / 4; i++) {
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w = (uint32_t *)(meta_backup + i * 4);
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flash_program_word(FLASH_META_START + i * 4, *w);
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for (i = 0; i < (signed) (sizeof(meta_backup) / 4); i++) {
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flash_program_word(FLASH_META_START + i * 4, meta_backup[i]);
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}
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flash_lock();
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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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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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storage_check_flash_errors();
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}
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void storage_loadDevice(LoadDevice *msg)
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@ -344,7 +368,7 @@ bool storage_hasPin(void)
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void storage_setPin(const char *pin)
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{
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if (pin && strlen(pin) > 0) {
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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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@ -376,28 +400,44 @@ bool session_isPinCached(void)
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return sessionPinCached;
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}
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void storage_resetPinFails(void)
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void storage_resetPinFails(uint32_t *pinfailsptr)
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{
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storage.has_pin_failed_attempts = true;
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storage.pin_failed_attempts = 0;
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storage_commit();
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}
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void storage_increasePinFails(void)
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{
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if (!storage.has_pin_failed_attempts) {
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storage.has_pin_failed_attempts = true;
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storage.pin_failed_attempts = 1;
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flash_clear_status_flags();
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flash_unlock();
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if ((uint32_t) (pinfailsptr + 1) - FLASH_STORAGE_PINAREA
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>= FLASH_STORAGE_PINAREA_LEN) {
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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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} else {
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storage.pin_failed_attempts++;
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flash_program_word((uint32_t) pinfailsptr, 0);
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}
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storage_commit();
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flash_lock();
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storage_check_flash_errors();
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}
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uint32_t storage_getPinFails(void)
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bool storage_increasePinFails(uint32_t *pinfailsptr)
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{
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storage_from_flash(STORAGE_VERSION); // reload from flash
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return storage.has_pin_failed_attempts ? storage.pin_failed_attempts : 0;
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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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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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return *pinfailsptr == newctr;
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}
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uint32_t *storage_getPinFailsPtr(void)
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{
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uint32_t *pinfailsptr = (uint32_t *) FLASH_STORAGE_PINAREA;
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while (*pinfailsptr == 0)
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pinfailsptr++;
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return pinfailsptr;
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}
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bool storage_isInitialized(void)
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@ -56,9 +56,9 @@ bool storage_hasPin(void);
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void storage_setPin(const char *pin);
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void session_cachePin(void);
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bool session_isPinCached(void);
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void storage_resetPinFails(void);
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void storage_increasePinFails(void);
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uint32_t storage_getPinFails(void);
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void storage_resetPinFails(uint32_t *pinfailptr);
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bool storage_increasePinFails(uint32_t *pinfailptr);
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uint32_t *storage_getPinFailsPtr(void);
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bool storage_isInitialized(void);
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