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// SPDX-FileCopyrightText: 2020 Foundation Devices, Inc. <hello@foundationdevices.com>
// SPDX-License-Identifier: GPL-3.0-or-later
//
// SPDX-FileCopyrightText: 2018 Coinkite, Inc. <coldcardwallet.com>
// SPDX-License-Identifier: GPL-3.0-only
//
/*
* (c) Copyright 2018 by Coinkite Inc. This file is part of Coldcard <coldcardwallet.com>
* and is covered by GPLv3 license found in COPYING.
*
* dispatch.c
*
* This code runs in an area of flash protected from viewing. It has limited entry
* point (via a special callgate) and checks state carefully before running other stuff.
*
*/
#include <errno.h>
#include <stdint.h>
#include <string.h>
#include <stdio.h>
#include "stm32h7xx_hal.h"
#include "utils.h"
#include "delay.h"
#include "pprng.h"
#include "se.h"
#include "sha256.h"
#include "version.h"
#include "gpio.h"
#include "se-atecc608a.h"
#include "pins.h"
#include "dispatch.h"
#define D1_AXISRAM_SIZE_MAX ((uint32_t)0x00080000U)
// memset4()
//
static inline void memset4(uint32_t *dest, uint32_t value, uint32_t byte_len)
{
for(; byte_len; byte_len-=4, dest++) {
*dest = value;
}
}
// wipe_all_sram()
//
static void wipe_all_sram(void)
{
#ifndef FIXME
return;
#else
const uint32_t noise = 0xdeadbeef;
// wipe all of SRAM (except our own memory, which was already wiped)
memset4((void *)D1_AXISRAM_BASE, noise, D1_AXISRAM_SIZE_MAX);
memset4((void *)SRAM2_BASE, noise, SRAM2_SIZE - BL_SRAM_SIZE);
#endif /* FIXME */
}
// fatal_error(const char *msg)
//
void
fatal_error(const char *msgvoid)
{
#ifdef FIXME
oled_setup();
oled_show(screen_fatal);
#endif
// Maybe should do a reset after a delay, like with
// the watchdog timer or something.
LOCKUP_FOREVER();
}
// fatal_mitm()
//
void fatal_mitm(void)
{
#ifdef FIXME
oled_setup();
oled_show(screen_mitm);
#endif
#ifdef RELEASE
wipe_all_sram();
#endif
printf("====================================!\n");
printf("FATAL MITM ATTACK! LOOPING FOREVER!\n");
printf("====================================!\n");
LOCKUP_FOREVER();
}
static int good_addr(const uint8_t *b, int minlen, int len, bool readonly)
{
uint32_t x = (uint32_t)b;
if (minlen) {
if (!b) return EFAULT; // gave no buffer
if (len < minlen) return ERANGE; // too small
}
if ((x >= D1_AXISRAM_BASE) && ((x - D1_AXISRAM_BASE) < D1_AXISRAM_SIZE_MAX)) {
// inside SRAM1, okay
return 0;
}
if (!readonly) {
return EPERM;
}
#ifdef FIXME
if ((x >= FIRMWARE_START) && (x - FIRMWARE_START) < FW_MAX_LENGTH) {
// inside flash of main firmware (happens for QSTR's)
return 0;
}
#endif /* FIXME */
return EACCES;
}
// se_dispatch()
//
// A C-runtime compatible env. is running, so do some work.
//
__attribute__ ((used))
int se_dispatch(
int method_num,
uint8_t *buf_io,
int len_in,
uint32_t arg2,
uint32_t incoming_sp,
uint32_t incoming_lr
)
{
int rv = 0;
// Important:
// - range check pointers so we aren't tricked into revealing our secrets
// - check buf_io points to main SRAM, and not into us!
// - range check len_in tightly
// - calling convention only gives me enough for 4 args to this function, so
// using read/write in place.
// - use arg2 use when a simple number is needed; never a pointer!
// - mpy may provide a pointer to flash if we give it a qstr or small value, and if
// we're reading only, that's fine.
if (len_in > 1024) { // arbitrary max, increase as needed
rv = ERANGE;
goto fail;
}
// Use these macros
#define REQUIRE_IN_ONLY(x) if ((rv = good_addr(buf_io, (x), len_in, true))) { goto fail; }
#define REQUIRE_OUT(x) if ((rv = good_addr(buf_io, (x), len_in, false))) { goto fail; }
printf("se_dispatch() method_num=%d\n", method_num);
switch(method_num) {
case CMD_GET_BOOTLOADER_VERSION: {
REQUIRE_OUT(64);
// Return my version string
memset(buf_io, 0, len_in);
#ifdef FIXME
strlcpy((char *)buf_io, version_string, len_in);
#else
memcpy(buf_io, version_string, len_in);
#endif
rv = strlen(version_string);
break;
}
#ifdef FIXME
case CMD_GET_FIRMWARE_HASH: {
// Perform SHA256 over ourselves, with 32-bits of salt, to imply we
// haven't stored valid responses.
REQUIRE_OUT(32);
SHA256_CTX ctx;
sha256_init(&ctx);
sha256_update(&ctx, (void *)&arg2, 4);
sha256_update(&ctx, (void *)BL_FLASH_BASE, BL_FLASH_SIZE);
sha256_final(&ctx, buf_io);
break;
}
#endif /* FIXME */
#ifdef FIXME
case CMD_UPGRADE_FIRMWARE: {
const uint8_t *scr;
bool secure = flash_is_security_level2();
// Go into DFU mode. It's a one-way trip.
// Also used to show some "fatal" screens w/ memory wipe.
switch (arg2) {
default:
case 0: // TODO: define constants once these are understood
// enter DFU for firmware upgrades
if (secure) {
// we cannot support DFU in secure mode anymore
rv = EPERM;
goto fail;
}
scr = screen_dfu;
break;
case 1:
// in case some way for Micropython to detect it.
scr = screen_downgrade;
break;
case 2:
scr = screen_blankish;
break;
case 3:
scr = screen_brick;
secure = true; // no point going into DFU, if even possible
break;
}
oled_setup();
oled_show(scr);
wipe_all_sram();
if (secure) {
// just die with that message shown; can't start DFU
LOCKUP_FOREVER();
} else {
// Cannot just call enter_dfu() because it doesn't work well
// once Micropython has configured so much stuff in the chip.
// Leave a reminder to ourselves
memcpy(dfu_flag->magic, REBOOT_TO_DFU, sizeof(dfu_flag->magic));
dfu_flag->screen = scr;
// reset system
NVIC_SystemReset();
// NOT-REACHED
}
break;
}
#endif /* FIXME */
case CMD_RESET:
// logout: wipe all of memory and lock up. Must powercycle to recover.
switch (arg2) {
case 0:
case 2:
#ifdef FIXME
oled_show(screen_logout);
#endif /* FIXME */
break;
case 1:
// leave screen untouched
break;
}
wipe_all_sram();
if (arg2 == 2) {
// need some time to show OLED contents
delay_ms(100);
// reboot so we can "login" again
NVIC_SystemReset();
// NOT-REACHED (but ok if it does)
}
// wait for an interrupt which will never happen (ie. sleep)
LOCKUP_FOREVER()
break;
case CMD_IS_BRICKED:
// Are we a brick?
// if the pairing secret doesn't work anymore, that
// means we've been bricked.
// TODO: also report hardware issue, and non-configured states
se_setup();
rv = (se_pair_unlock() != 0);
break;
case CMD_READ_SE_SLOT: {
// Read a dataslot directly. Will fail on
// encrypted slots.
if (len_in != 4 && len_in != 32 && len_in != 72) {
rv = ERANGE;
} else {
REQUIRE_OUT(4);
se_setup();
if (se_read_data_slot(arg2 & 0xf, buf_io, len_in)) {
rv = EIO;
}
}
break;
}
case CMD_GET_ANTI_PHISHING_WORDS: {
// Provide the 2 words for anti-phishing.
REQUIRE_OUT(MAX_PIN_LEN);
// arg2: length of pin.
if ((arg2 < 1) || (arg2 > MAX_PIN_LEN)) {
rv = ERANGE;
} else {
if (anti_phishing_words((char *)buf_io, arg2, (uint32_t *)buf_io)) {
rv = EIO;
}
}
break;
}
case CMD_GET_SUPPLY_CHAIN_VALIDATION_WORDS: {
// Provide a hash to use for the supply chain validation words'
if (supply_chain_validation_words((char *)buf_io, arg2, (uint32_t *)buf_io)) {
rv = EIO;
}
break;
}
case CMD_GET_RANDOM_BYTES:
rng_buffer(buf_io, len_in);
break;
case CMD_PIN_CONTROL: {
// Try login w/ PIN.
REQUIRE_OUT(PIN_ATTEMPT_SIZE_V1);
pinAttempt_t *args = (pinAttempt_t *)buf_io;
switch (arg2) {
case PIN_SETUP:
rv = pin_setup_attempt(args);
break;
case PIN_ATTEMPT:
rv = pin_login_attempt(args);
break;
case PIN_CHANGE:
rv = pin_change(args);
break;
case PIN_GET_SECRET:
rv = pin_fetch_secret(args);
break;
case PIN_LONG_SECRET:
rv = pin_long_secret(args);
break;
default:
rv = ENOENT;
break;
}
break;
}
case CMD_GET_SE_CONFIG:
// Read out entire config dataspace
REQUIRE_OUT(128);
se_setup();
rv = se_config_read(buf_io);
if(rv) {
rv = EIO;
}
break;
default:
rv = ENOENT;
break;
}
#undef REQUIRE_IN_ONLY
#undef REQUIRE_OUT
fail:
// Precaution: we don't want to leave ATECC508A authorized for any specific keys,
// perhaps due to an error path we didn't see. Always reset the chip.
se_reset_chip();
return rv;
}