update bootloader to 1.4.0 via firmware, run unsigned firmware in unprivileged mode

bootloader/bootloader.c

@@ -78,12 +78,10 @@ void show_unofficial_warning(const uint8_t *hash)
 
 void __attribute__((noreturn)) load_app(int signed_firmware)
 {
-	(void)signed_firmware;
-
 	// zero out SRAM
 	memset_reg(_ram_start, _ram_end, 0);
 
-	load_vector_table((const vector_table_t *) FLASH_APP_START);
+	jump_to_firmware((const vector_table_t *) FLASH_APP_START, signed_firmware);
 }
 
 bool firmware_present(void)

firmware/.gitignore

@@ -2,3 +2,5 @@ coins_array.h
 coins_count.h
 
 nem_mosaics.[ch]
+
+bl_data.h

firmware/Makefile

@@ -13,6 +13,7 @@ else
 OBJS += usb.o
 endif
 
+OBJS += bl_check.o
 OBJS += u2f.o
 OBJS += messages.o
 OBJS += storage.o
@@ -120,6 +121,10 @@ coins_array.h: coins-gen.py coins.json
 nem_mosaics.c nem_mosaics.h: nem_mosaics.py nem_mosaics.json
 	$(PYTHON) $<
 
+bl_data.h: bl_data-gen.py ../bootloader/bootloader.bin
+	$(PYTHON) $<
+
 clean::
 	rm -f coins_count.h coins_array.h
 	rm -f nem_mosaics.c nem_mosaics.h
+	rm -f bl_data.h

firmware/bl_check.c

@@ -0,0 +1,75 @@
+/*
+ * This file is part of the TREZOR project, https://trezor.io/
+ *
+ * Copyright (C) 2018 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 <stdint.h>
+#include <string.h>
+#include <libopencm3/stm32/flash.h>
+#include "bl_data.h"
+#include "memory.h"
+#include "layout.h"
+#include "gettext.h"
+#include "util.h"
+
+int known_bootloader(int r, const uint8_t *hash) {
+	if (r != 32) return 0;
+	if (0 == memcmp(hash, "\xbf\x72\xe2\x5e\x2c\x2f\xc1\xba\x57\x04\x50\xfa\xdf\xb6\x6f\xaa\x5a\x71\x6d\xcd\xc0\x33\x35\x88\x55\x7b\x77\x54\x0a\xb8\x7e\x98", 32)) return 1;  // 1.2.0a
+	if (0 == memcmp(hash, "\x77\xb8\xe2\xf2\x5f\xaa\x8e\x8c\x7d\x9f\x5b\x32\x3b\x27\xce\x05\x6c\xa3\xdb\xc2\x3f\x56\xc3\x7e\xe3\x3f\x97\x7c\xa6\xeb\x4d\x3e", 32)) return 1;  // 1.2.0b
+	if (0 == memcmp(hash, "\xc4\xc3\x25\x39\xb4\xa0\x25\xa8\xe7\x53\xa4\xc4\x62\x64\x28\x59\x11\xa4\x5f\xcb\x14\xf4\x71\x81\x79\xe7\x11\xb1\xce\x99\x05\x24", 32)) return 1;  // 1.2.5
+	if (0 == memcmp(hash, "\x42\x59\x66\x94\xa0\xf2\x9d\x1e\xc2\x35\x71\x29\x2d\x54\x39\xd8\x2f\xa1\x8c\x07\x37\xcb\x10\x7e\x98\xf6\x1e\xf5\x93\x4d\xe7\x16", 32)) return 1;  // 1.3.0a
+	if (0 == memcmp(hash, "\x3a\xcf\x2e\x51\x0b\x0f\xe1\x56\xb5\x58\xbb\xf7\x9c\x7e\x48\x5e\xb0\x26\xe5\xe0\x8c\xb4\x4d\x15\x2d\x44\xd6\x4e\x0c\x6a\x41\x37", 32)) return 1;  // 1.3.0b
+	if (0 == memcmp(hash, "\x15\x85\x21\x5b\xc6\xe5\x5a\x34\x07\xa8\xb3\xee\xe2\x79\x03\x4e\x95\xb9\xc4\x34\x00\x33\xe1\xb6\xae\x16\x0c\xe6\x61\x19\x67\x15", 32)) return 1;  // 1.3.1
+	if (0 == memcmp(hash, "\x76\x51\xb7\xca\xba\x5a\xae\x0c\xc1\xc6\x5c\x83\x04\xf7\x60\x39\x6f\x77\x60\x6c\xd3\x99\x0c\x99\x15\x98\xf0\xe2\x2a\x81\xe0\x07", 32)) return 1;  // 1.3.2
+	if (0 == memcmp(hash, "\x8c\xe8\xd7\x9e\xdf\x43\x0c\x03\x42\x64\x68\x6c\xa9\xb1\xd7\x8d\x26\xed\xb2\xac\xab\x71\x39\xbe\x8f\x98\x5c\x2a\x3c\x6c\xae\x11", 32)) return 1;  // 1.3.3
+	if (0 == memcmp(hash, "\x63\x30\xfc\xec\x16\x72\xfa\xd3\x0b\x42\x1b\x60\xf7\x4f\x83\x9a\x39\x39\x33\x45\x65\xcb\x70\x3b\x2b\xd7\x18\x2e\xa2\xdd\xa0\x19", 32)) return 1;  // 1.4.0
+	return 0;
+}
+
+void check_bootloader(void)
+{
+	uint8_t hash[32];
+	int r = memory_bootloader_hash(hash);
+
+	if (!known_bootloader(r, hash)) {
+		layoutDialog(&bmp_icon_error, NULL, NULL, NULL, "Unknown bootloader", "detected.", NULL, "Unplug your TREZOR", "contact our support.", NULL);
+		system_halt();
+	}
+
+	if (r == 32 && 0 == memcmp(hash, bl_hash, 32)) {
+		// all OK -> done
+		return;
+	}
+
+	// unlock sectors
+	memory_write_unlock();
+
+	// replace bootloader
+	flash_unlock();
+	for (int i = FLASH_BOOT_SECTOR_FIRST; i <= FLASH_BOOT_SECTOR_LAST; i++) {
+		flash_erase_sector(i, FLASH_CR_PROGRAM_X32);
+	}
+	for (int i = 0; i < FLASH_BOOT_LEN / 4; i++) {
+		const uint32_t *w = (const uint32_t *)(bl_data + i * 4);
+		flash_program_word(FLASH_BOOT_START + i * 4, *w);
+	}
+	flash_lock();
+
+	// show info and halt
+	layoutDialog(&bmp_icon_info, NULL, NULL, NULL, _("Update finished"), _("successfully."), NULL, _("Please reconnect"), _("the device."), NULL);
+	system_halt();
+}

firmware/bl_check.h

@@ -0,0 +1,25 @@
+/*
+ * This file is part of the TREZOR project, https://trezor.io/
+ *
+ * Copyright (C) 2018 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 __BL_CHECK_H__
+#define __BL_CHECK_H__
+
+void check_bootloader(void);
+
+#endif

firmware/bl_data-gen.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python
+from hashlib import sha256
+
+fn = '../bootloader/bootloader.bin'
+
+data = open(fn, 'rb').read()
+if len(data) > 32768:
+    raise Exception('bootloader has to be smaller than 32768 bytes')
+
+data += b'\x00' * (32768 - len(data))
+
+h = sha256(sha256(data).digest()).digest()
+
+bl_hash = ', '.join('0x%02x' % x for x in bytearray(h))
+bl_data = ', '.join('0x%02x' % x for x in bytearray(data))
+
+with open('bl_data.h', 'wt') as f:
+    f.write('static const uint8_t bl_hash[32] = {%s};\n' % bl_hash)
+    f.write('static const uint8_t bl_data[32768] = {%s};\n' % bl_data)

firmware/fastflash.c

@@ -37,5 +37,5 @@ void __attribute__((noreturn)) run_bootloader(void)
 	// copy bootloader
 	memcpy(bootloader_vec, __bootloader_start__, (size_t) __bootloader_size__);
 
-	load_vector_table(bootloader_vec);
+	jump_to_firmware(bootloader_vec, FW_TRUSTED);
 }

firmware/trezor.c

@@ -30,6 +30,7 @@
 #include "timer.h"
 #include "buttons.h"
 #include "gettext.h"
+#include "bl_check.h"
 #include "fastflash.h"
 
 /* Screen timeout */
@@ -91,6 +92,7 @@ int main(void)
 	__stack_chk_guard = random32(); // this supports compiler provided unpredictable stack protection checks
 	oledInit();
 #else
+	check_bootloader();
 	setupApp();
 	__stack_chk_guard = random32(); // this supports compiler provided unpredictable stack protection checks
 #endif

memory.c

@@ -49,7 +49,25 @@ void memory_protect(void)
 #endif
 }
 
+// Remove write-protection on all flash sectors.
+//
+// This is an undocumented feature/bug of STM32F205/F405 microcontrollers,
+// where flash controller reads its write protection bits from FLASH_OPTCR
+// register not from OPTION_BYTES, rendering write protection useless.
+// This behaviour is fixed in future designs of flash controller used for
+// example in STM32F427, where the protection bits are read correctly
+// from OPTION_BYTES and not form FLASH_OPCTR register.
+//
+// Read protection is unaffected and always stays locked to the desired value.
+void memory_write_unlock(void)
+{
+	flash_unlock_option_bytes();
+	flash_program_option_bytes(0x0FFFCCEC);
+	flash_lock_option_bytes();
+}
+
 int memory_bootloader_hash(uint8_t *hash)
+
 {
 	sha256_Raw((const uint8_t *)FLASH_BOOT_START, FLASH_BOOT_LEN, hash);
 	sha256_Raw(hash, 32, hash);

memory.h

@@ -103,6 +103,7 @@
 #define FLASH_CODE_SECTOR_LAST	7
 
 void memory_protect(void);
+void memory_write_unlock(void);
 int memory_bootloader_hash(uint8_t *hash);
 
 #endif

util.h

@@ -21,6 +21,7 @@
 #define __UTIL_H_
 
 #include <stdint.h>
+#include <setup.h>
 
 #if !EMULATOR
 #include <libopencm3/cm3/scb.h>
@@ -52,10 +53,16 @@ extern uint8_t _ram_start[], _ram_end[];
 // defined in startup.s
 extern void memset_reg(void *start, void *stop, uint32_t val);
 
-static inline void __attribute__((noreturn)) load_vector_table(const vector_table_t *vector_table)
+#define FW_SIGNED       0x5A3CA5C3
+#define FW_UNTRUSTED    0x00000000
+
+static inline void __attribute__((noreturn)) jump_to_firmware(const vector_table_t *vector_table, int trust)
 {
-	// Relocate vector table
-	SCB_VTOR = (uint32_t)vector_table;
+	if (FW_SIGNED == trust) {                 // trusted signed firmware
+		SCB_VTOR = (uint32_t)vector_table;    // * relocate vector table
+	} else {                                  // untrusted firmware
+		mpu_config();                         // * configure MPU
+	}
 
 	// Set stack pointer
 	__asm__ volatile("msr msp, %0" :: "r" (vector_table->initial_sp_value));