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/* Copyright 2016 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "2sha.h"
#include "bdb.h"
#include "bdb_api.h"
#include "host.h"
static f_extend extend = vb2_sha256_extend;
static void help(void)
{
fprintf(stderr,
"Usage: bdb_extend -b bdb_file -s bds_file "
"[-d digest_file] [-m]\n"
"\n"
"Extends BDS based on a given BDB. When '-m' is given, a "
"MVMAP2315's sha256_extend algorithm will be used. When "
"digest_file is specified, the validity of the BDB key is "
"checked and the secrets will be derived differently.\n");
}
#define PACK32(str, x) \
{ \
*(x) = ((uint32_t) *((str) + 3) ) \
| ((uint32_t) *((str) + 2) << 8) \
| ((uint32_t) *((str) + 1) << 16) \
| ((uint32_t) *((str) + 0) << 24); \
}
/**
* MVMAP2315's implementation of sha256 extend
*
* This performs incorrect but still cryptographically secure sha256 extension.
* This is provided for test purpose only.
*
* See vb2_sha256_extend for details on arguments.
*/
static void mvmap2315_sha256_extend(const uint8_t *from, const uint8_t *by,
uint8_t *to)
{
struct vb2_sha256_context dc;
int i;
vb2_sha256_init(&dc);
for (i = 0; i < 8; i++) {
PACK32(from, &dc.h[i]);
from += 4;
}
vb2_sha256_update(&dc, by, VB2_SHA256_BLOCK_SIZE);
vb2_sha256_finalize(&dc, to);
}
static void dump_secret(const uint8_t *secret, const char *label)
{
int i;
printf("%s = {", label);
for (i = 0; i < BDB_SECRET_SIZE; i++) {
if (i % 8 == 0)
printf("\n\t");
else
printf(" ");
printf("0x%02x,", secret[i]);
}
printf("\n}\n");
}
static void dump_secrets(struct vba_context *ctx, const uint8_t *wsr)
{
dump_secret(ctx->secrets->bdb, "bdb");
dump_secret(ctx->secrets->boot_path, "boot_path");
dump_secret(ctx->secrets->boot_verified, "boot_verified");
dump_secret(ctx->secrets->nvm_wp, "nvm_wp");
dump_secret(ctx->secrets->nvm_rw, "nvm_rw");
dump_secret(wsr, "wsr");
}
static int derive_secrets(struct vba_context *ctx,
const uint8_t *bdb, uint8_t *wsr)
{
struct bdb_secrets secrets;
memset(&secrets, 0, sizeof(secrets));
ctx->secrets = &secrets;
if (vba_extend_secrets_ro(ctx, bdb, wsr, extend)) {
fprintf(stderr, "ERROR: Failed to derive secrets\n");
return -1;
}
fprintf(stderr, "LOG: Secrets are derived as follows\n");
dump_secrets(ctx, wsr);
return 0;
}
int main(int argc, char *argv[])
{
struct vba_context ctx;
uint8_t *bdb, *bds;
uint8_t *key_digest = NULL;
uint32_t bdb_size, bds_size, digest_size;
const char *bdb_file = NULL;
const char *digest_file = NULL;
const char *bds_file = NULL;
int rv;
int opt;
while ((opt = getopt(argc, argv, "b:d:hms:")) != -1) {
switch(opt) {
case 'b':
bdb_file = optarg;
break;
case 'd':
digest_file = optarg;
break;
case 'h':
help();
return 0;
case 'm':
extend = mvmap2315_sha256_extend;
break;
case 's':
bds_file = optarg;
break;
default:
help();
return -1;
}
}
if (!bdb_file || !bds_file) {
fprintf(stderr, "ERROR: BDB and BDS aren't specified\n\n");
help();
return -1;
}
/* Read BDB */
bdb = read_file(bdb_file, &bdb_size);
if (!bdb) {
fprintf(stderr, "ERROR: Unable to read %s\n", bdb_file);
return -1;
}
/* Read BDS */
bds = read_file(bds_file, &bds_size);
if (!bds) {
fprintf(stderr, "ERROR: Unable to read %s\n", bds_file);
return -1;
}
if (bds_size != BDB_SECRET_SIZE) {
fprintf(stderr, "ERROR: Invalid BDS size: %d\n", bds_size);
return -1;
}
/* Read key digest if provided */
if (digest_file) {
key_digest = read_file(digest_file, &digest_size);
if (!key_digest) {
fprintf(stderr,
"ERROR: Unable to read %s\n", digest_file);
return -1;
}
}
/* Verify BDB and set a flag based on the result */
memset(&ctx, 0, sizeof(ctx));
rv = bdb_verify(bdb, bdb_size, key_digest);
if (rv) {
if (rv != BDB_GOOD_OTHER_THAN_KEY) {
fprintf(stderr, "ERROR: BDB is invalid: %d\n", rv);
return -1;
}
fprintf(stderr,
"WARNING: BDB is valid but key digest doesn't match\n");
} else {
ctx.flags |= VBA_CONTEXT_FLAG_BDB_KEY_EFUSED;
fprintf(stderr, "BDB is successfully verified by eFused key\n");
}
/* Derive secrets and dump the values */
return derive_secrets(&ctx, bdb, bds);
}
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