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firmware: use OTP block 3 for storing randomness

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This commit is contained in:
Pavol Rusnak 2019-02-18 17:57:09 +01:00
parent 402e7c4ec6
commit 540be49897
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GPG Key ID: 91F3B339B9A02A3D
5 changed files with 129 additions and 14 deletions
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2
common.h
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@ -23,7 +23,7 @@
#include <stdint.h>
#include "secbool.h"
#define HW_ENTROPY_LEN 12
#define HW_ENTROPY_LEN (12 + 32)
extern uint8_t HW_ENTROPY_DATA[HW_ENTROPY_LEN];
void __attribute__((noreturn)) __fatal_error(const char *expr, const char *msg, const char *file, int line, const char *func);

1
firmware/Makefile
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@ -7,6 +7,7 @@ OBJS += udp.o
else
OBJS += usb.o
OBJS += bl_check.o
OBJS += otp.o
endif
OBJS += u2f.o

65
firmware/otp.c Normal file
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@ -0,0 +1,65 @@
/*
* This file is part of the TREZOR project, https://trezor.io/
*
* Copyright (C) 2019 Pavol Rusnak <stick@satoshilabs.com>
*
* This library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include <libopencm3/stm32/flash.h>
#include "otp.h"
#define FLASH_OTP_BASE 0x1FFF7800U
#define FLASH_OTP_LOCK_BASE 0x1FFF7A00U
bool flash_otp_is_locked(uint8_t block)
{
return 0x00 == *(volatile uint8_t *)(FLASH_OTP_LOCK_BASE + block);
}
bool flash_otp_lock(uint8_t block)
{
if (block >= FLASH_OTP_NUM_BLOCKS) {
return false;
}
flash_unlock();
flash_program_byte(FLASH_OTP_LOCK_BASE + block, 0x00);
flash_lock();
return true;
}
bool flash_otp_read(uint8_t block, uint8_t offset, uint8_t *data, uint8_t datalen)
{
if (block >= FLASH_OTP_NUM_BLOCKS || offset + datalen > FLASH_OTP_BLOCK_SIZE) {
return false;
}
for (uint8_t i = 0; i < datalen; i++) {
data[i] = *(volatile uint8_t *)(FLASH_OTP_BASE + block * FLASH_OTP_BLOCK_SIZE + offset + i);
}
return true;
}
bool flash_otp_write(uint8_t block, uint8_t offset, const uint8_t *data, uint8_t datalen)
{
if (block >= FLASH_OTP_NUM_BLOCKS || offset + datalen > FLASH_OTP_BLOCK_SIZE) {
return false;
}
flash_unlock();
for (uint8_t i = 0; i < datalen; i++) {
uint32_t address = FLASH_OTP_BASE + block * FLASH_OTP_BLOCK_SIZE + offset + i;
flash_program_byte(address, data[i]);
}
flash_lock();
return true;
}

36
firmware/otp.h Normal file
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@ -0,0 +1,36 @@
/*
* This file is part of the TREZOR project, https://trezor.io/
*
* Copyright (C) 2019 Pavol Rusnak <stick@satoshilabs.com>
*
* This library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __OTP_H__
#define __OTP_H__
#include <stdint.h>
#include <stdbool.h>
#define FLASH_OTP_NUM_BLOCKS 16
#define FLASH_OTP_BLOCK_SIZE 32
#define FLASH_OTP_BLOCK_RANDOMNESS 3
bool flash_otp_is_locked(uint8_t block);
bool flash_otp_lock(uint8_t block);
bool flash_otp_read(uint8_t block, uint8_t offset, uint8_t *data, uint8_t datalen);
bool flash_otp_write(uint8_t block, uint8_t offset, const uint8_t *data, uint8_t datalen);
#endif

39
firmware/trezor.c
View File

@ -34,6 +34,7 @@
#include "bl_check.h"
#include "memzero.h"
#if !EMULATOR
#include "otp.h"
#include <libopencm3/stm32/desig.h>
#endif
@ -89,6 +90,29 @@ void check_lock_screen(void)
}
}
static void collect_hw_entropy(bool privileged)
{
#if EMULATOR
memzero(HW_ENTROPY_DATA, HW_ENTROPY_LEN);
#else
if (privileged) {
desig_get_unique_id((uint32_t *)HW_ENTROPY_DATA);
// set entropy in the OTP randomness block
if (!flash_otp_is_locked(FLASH_OTP_BLOCK_RANDOMNESS)) {
uint8_t entropy[FLASH_OTP_BLOCK_SIZE];
random_buffer(entropy, FLASH_OTP_BLOCK_SIZE);
flash_otp_write(FLASH_OTP_BLOCK_RANDOMNESS, 0, entropy, FLASH_OTP_BLOCK_SIZE);
flash_otp_lock(FLASH_OTP_BLOCK_RANDOMNESS);
}
// collect entropy from OTP randomness block
flash_otp_read(FLASH_OTP_BLOCK_RANDOMNESS, 0, HW_ENTROPY_DATA + 12, FLASH_OTP_BLOCK_SIZE);
} else {
// unprivileged mode => use fixed HW_ENTROPY
memset(HW_ENTROPY_DATA, 0x3C, HW_ENTROPY_LEN);
}
#endif
}
int main(void)
{
#ifndef APPVER
@ -100,26 +124,15 @@ int main(void)
setupApp();
__stack_chk_guard = random32(); // this supports compiler provided unpredictable stack protection checks
#endif
#if EMULATOR
memzero(HW_ENTROPY_DATA, HW_ENTROPY_LEN);
#endif
if (!is_mode_unprivileged()) {
#if !EMULATOR
desig_get_unique_id((uint32_t*)HW_ENTROPY_DATA);
#endif
collect_hw_entropy(true);
timer_init();
#ifdef APPVER
// enable MPU (Memory Protection Unit)
mpu_config();
#endif
} else {
#if !EMULATOR
// we are running in unprivileged mode
// use fixed HW_ENTROPY
memset(HW_ENTROPY_DATA, 0x3C, HW_ENTROPY_LEN);
#endif
collect_hw_entropy(false);
}
#if DEBUG_LINK