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trezor-firmware/legacy/bootloader/signatures.c
matejcik 6aa05f8a6f MONOREPO MERGE trezor-mcu
2019-04-15 19:14:58 +02:00

204 lines
8.0 KiB
C
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/*
* This file is part of the TREZOR project, https://trezor.io/
*
* Copyright (C) 2014 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 <string.h>
#include "bootloader.h"
#include "ecdsa.h"
#include "memory.h"
#include "memzero.h"
#include "secp256k1.h"
#include "sha2.h"
#include "signatures.h"
const uint32_t FIRMWARE_MAGIC_OLD = 0x525a5254; // TRZR
const uint32_t FIRMWARE_MAGIC_NEW = 0x465a5254; // TRZF
#define PUBKEYS 5
static const uint8_t * const pubkey[PUBKEYS] = {
(const uint8_t *)"\x04\xd5\x71\xb7\xf1\x48\xc5\xe4\x23\x2c\x38\x14\xf7\x77\xd8\xfa\xea\xf1\xa8\x42\x16\xc7\x8d\x56\x9b\x71\x04\x1f\xfc\x76\x8a\x5b\x2d\x81\x0f\xc3\xbb\x13\x4d\xd0\x26\xb5\x7e\x65\x00\x52\x75\xae\xde\xf4\x3e\x15\x5f\x48\xfc\x11\xa3\x2e\xc7\x90\xa9\x33\x12\xbd\x58",
(const uint8_t *)"\x04\x63\x27\x9c\x0c\x08\x66\xe5\x0c\x05\xc7\x99\xd3\x2b\xd6\xba\xb0\x18\x8b\x6d\xe0\x65\x36\xd1\x10\x9d\x2e\xd9\xce\x76\xcb\x33\x5c\x49\x0e\x55\xae\xe1\x0c\xc9\x01\x21\x51\x32\xe8\x53\x09\x7d\x54\x32\xed\xa0\x6b\x79\x20\x73\xbd\x77\x40\xc9\x4c\xe4\x51\x6c\xb1",
(const uint8_t *)"\x04\x43\xae\xdb\xb6\xf7\xe7\x1c\x56\x3f\x8e\xd2\xef\x64\xec\x99\x81\x48\x25\x19\xe7\xef\x4f\x4a\xa9\x8b\x27\x85\x4e\x8c\x49\x12\x6d\x49\x56\xd3\x00\xab\x45\xfd\xc3\x4c\xd2\x6b\xc8\x71\x0d\xe0\xa3\x1d\xbd\xf6\xde\x74\x35\xfd\x0b\x49\x2b\xe7\x0a\xc7\x5f\xde\x58",
(const uint8_t *)"\x04\x87\x7c\x39\xfd\x7c\x62\x23\x7e\x03\x82\x35\xe9\xc0\x75\xda\xb2\x61\x63\x0f\x78\xee\xb8\xed\xb9\x24\x87\x15\x9f\xff\xed\xfd\xf6\x04\x6c\x6f\x8b\x88\x1f\xa4\x07\xc4\xa4\xce\x6c\x28\xde\x0b\x19\xc1\xf4\xe2\x9f\x1f\xcb\xc5\xa5\x8f\xfd\x14\x32\xa3\xe0\x93\x8a",
(const uint8_t *)"\x04\x73\x84\xc5\x1a\xe8\x1a\xdd\x0a\x52\x3a\xdb\xb1\x86\xc9\x1b\x90\x6f\xfb\x64\xc2\xc7\x65\x80\x2b\xf2\x6d\xbd\x13\xbd\xf1\x2c\x31\x9e\x80\xc2\x21\x3a\x13\x6c\x8e\xe0\x3d\x78\x74\xfd\x22\xb7\x0d\x68\xe7\xde\xe4\x69\xde\xcf\xbb\xb5\x10\xee\x9a\x46\x0c\xda\x45",
};
#define SIGNATURES 3
#define FLASH_META_START 0x08008000
#define FLASH_META_CODELEN (FLASH_META_START + 0x0004)
#define FLASH_META_SIGINDEX1 (FLASH_META_START + 0x0008)
#define FLASH_META_SIGINDEX2 (FLASH_META_START + 0x0009)
#define FLASH_META_SIGINDEX3 (FLASH_META_START + 0x000A)
#define FLASH_OLD_APP_START 0x08010000
#define FLASH_META_SIG1 (FLASH_META_START + 0x0040)
#define FLASH_META_SIG2 (FLASH_META_START + 0x0080)
#define FLASH_META_SIG3 (FLASH_META_START + 0x00C0)
bool firmware_present_old(void) {
if (memcmp(FLASH_PTR(FLASH_META_START), &FIRMWARE_MAGIC_OLD,
4)) { // magic does not match
return false;
}
if (*((const uint32_t *)FLASH_PTR(FLASH_META_CODELEN)) <
8192) { // firmware reports smaller size than 8192
return false;
}
if (*((const uint32_t *)FLASH_PTR(FLASH_META_CODELEN)) >
FLASH_APP_LEN) { // firmware reports bigger size than flash size
return false;
}
return true;
}
int signatures_old_ok(void) {
const uint32_t codelen = *((const uint32_t *)FLASH_META_CODELEN);
const uint8_t sigindex1 = *((const uint8_t *)FLASH_META_SIGINDEX1);
const uint8_t sigindex2 = *((const uint8_t *)FLASH_META_SIGINDEX2);
const uint8_t sigindex3 = *((const uint8_t *)FLASH_META_SIGINDEX3);
if (codelen > FLASH_APP_LEN) {
return false;
}
uint8_t hash[32];
sha256_Raw(FLASH_PTR(FLASH_OLD_APP_START), codelen, hash);
if (sigindex1 < 1 || sigindex1 > PUBKEYS) return SIG_FAIL; // invalid index
if (sigindex2 < 1 || sigindex2 > PUBKEYS) return SIG_FAIL; // invalid index
if (sigindex3 < 1 || sigindex3 > PUBKEYS) return SIG_FAIL; // invalid index
if (sigindex1 == sigindex2) return SIG_FAIL; // duplicate use
if (sigindex1 == sigindex3) return SIG_FAIL; // duplicate use
if (sigindex2 == sigindex3) return SIG_FAIL; // duplicate use
if (0 != ecdsa_verify_digest(&secp256k1, pubkey[sigindex1 - 1],
(const uint8_t *)FLASH_META_SIG1,
hash)) { // failure
return SIG_FAIL;
}
if (0 != ecdsa_verify_digest(&secp256k1, pubkey[sigindex2 - 1],
(const uint8_t *)FLASH_META_SIG2,
hash)) { // failure
return SIG_FAIL;
}
if (0 != ecdsa_verify_digest(&secp256k1, pubkey[sigindex3 - 1],
(const uint8_t *)FLASH_META_SIG3,
hash)) { // failture
return SIG_FAIL;
}
return SIG_OK;
}
void compute_firmware_fingerprint(const image_header *hdr, uint8_t hash[32]) {
image_header copy;
memcpy(&copy, hdr, sizeof(image_header));
memzero(copy.sig1, sizeof(copy.sig1));
memzero(copy.sig2, sizeof(copy.sig2));
memzero(copy.sig3, sizeof(copy.sig3));
copy.sigindex1 = 0;
copy.sigindex2 = 0;
copy.sigindex3 = 0;
sha256_Raw((const uint8_t *)&copy, sizeof(image_header), hash);
}
bool firmware_present_new(void) {
const image_header *hdr =
(const image_header *)FLASH_PTR(FLASH_FWHEADER_START);
if (hdr->magic != FIRMWARE_MAGIC_NEW) return false;
// we need to ignore hdrlen for now
// because we keep reset_handler ptr there
// for compatibility with older bootloaders
// after this is no longer necessary, let's uncomment the line below:
// if (hdr->hdrlen != FLASH_FWHEADER_LEN) return false;
if (hdr->codelen > FLASH_APP_LEN) return false;
if (hdr->codelen < 4096) return false;
return true;
}
int signatures_new_ok(const image_header *hdr, uint8_t store_fingerprint[32]) {
uint8_t hash[32];
compute_firmware_fingerprint(hdr, hash);
if (store_fingerprint) {
memcpy(store_fingerprint, hash, 32);
}
if (hdr->sigindex1 < 1 || hdr->sigindex1 > PUBKEYS)
return SIG_FAIL; // invalid index
if (hdr->sigindex2 < 1 || hdr->sigindex2 > PUBKEYS)
return SIG_FAIL; // invalid index
if (hdr->sigindex3 < 1 || hdr->sigindex3 > PUBKEYS)
return SIG_FAIL; // invalid index
if (hdr->sigindex1 == hdr->sigindex2) return SIG_FAIL; // duplicate use
if (hdr->sigindex1 == hdr->sigindex3) return SIG_FAIL; // duplicate use
if (hdr->sigindex2 == hdr->sigindex3) return SIG_FAIL; // duplicate use
if (0 != ecdsa_verify_digest(&secp256k1, pubkey[hdr->sigindex1 - 1],
hdr->sig1, hash)) { // failure
return SIG_FAIL;
}
if (0 != ecdsa_verify_digest(&secp256k1, pubkey[hdr->sigindex2 - 1],
hdr->sig2, hash)) { // failure
return SIG_FAIL;
}
if (0 != ecdsa_verify_digest(&secp256k1, pubkey[hdr->sigindex3 - 1],
hdr->sig3, hash)) { // failure
return SIG_FAIL;
}
return SIG_OK;
}
int mem_is_empty(const uint8_t *src, uint32_t len) {
for (uint32_t i = 0; i < len; i++) {
if (src[i]) return 0;
}
return 1;
}
int check_firmware_hashes(const image_header *hdr) {
uint8_t hash[32];
// check hash of the first code chunk
sha256_Raw(FLASH_PTR(FLASH_APP_START), (64 - 1) * 1024, hash);
if (0 != memcmp(hash, hdr->hashes, 32)) return SIG_FAIL;
// check remaining used chunks
uint32_t total_len = FLASH_FWHEADER_LEN + hdr->codelen;
int used_chunks = total_len / FW_CHUNK_SIZE;
if (total_len % FW_CHUNK_SIZE > 0) {
used_chunks++;
}
for (int i = 1; i < used_chunks; i++) {
sha256_Raw(FLASH_PTR(FLASH_FWHEADER_START + (64 * i) * 1024), 64 * 1024,
hash);
if (0 != memcmp(hdr->hashes + 32 * i, hash, 32)) return SIG_FAIL;
}
// check unused chunks
for (int i = used_chunks; i < 16; i++) {
if (!mem_is_empty(hdr->hashes + 32 * i, 32)) return SIG_FAIL;
}
// all OK
return SIG_OK;
}
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