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/* Copyright (c) 2014 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.
*/
/*
* Implementation of the RW firmware signature verification and jump.
*/
#include "console.h"
#include "ec_commands.h"
#include "rsa.h"
#include "sha256.h"
#include "shared_mem.h"
#include "system.h"
#include "usb_pd.h"
#include "util.h"
/* Console output macros */
#define CPRINTF(format, args...) cprintf(CC_SYSTEM, format, ## args)
#define CPRINTS(format, args...) cprints(CC_SYSTEM, format, ## args)
/* RW firmware reset vector */
static uint32_t * const rw_rst =
(uint32_t *)(CONFIG_PROGRAM_MEMORY_BASE + CONFIG_RW_MEM_OFF + 4);
void check_rw_signature(void)
{
struct sha256_ctx ctx;
int good, res;
uint8_t *hash;
uint32_t *rsa_workbuf;
/* Only the Read-Only firmware needs to do the signature check */
if (system_get_image_copy() != SYSTEM_IMAGE_RO)
return;
/* Check if we have a RW firmware flashed */
if (*rw_rst == 0xffffffff)
return;
CPRINTS("Verifying RW image...");
/* Large buffer for RSA computation : could be re-use afterwards... */
res = shared_mem_acquire(3 * RSANUMBYTES, (char **)&rsa_workbuf);
if (res) {
CPRINTS("No memory for RW verification");
return;
}
/* SHA-256 Hash of the RW firmware */
/* TODO(crosbug.com/p/44803): Do we have to hash the whole region? */
SHA256_init(&ctx);
SHA256_update(&ctx, (void *)CONFIG_PROGRAM_MEMORY_BASE
+ CONFIG_RW_MEM_OFF,
CONFIG_RW_SIZE - CONFIG_RW_SIG_SIZE);
hash = SHA256_final(&ctx);
good = rsa_verify((const struct rsa_public_key *)CONFIG_RO_PUBKEY_ADDR,
(const uint8_t *)CONFIG_RW_SIG_ADDR,
hash, rsa_workbuf);
if (good) {
CPRINTS("RW image verified");
/* Jump to the RW firmware */
system_run_image_copy(SYSTEM_IMAGE_RW);
} else {
CPRINTS("RSA verify FAILED");
pd_log_event(PD_EVENT_ACC_RW_FAIL, 0, 0, NULL);
/* RW firmware is invalid : do not jump there */
if (system_is_locked())
system_disable_jump();
}
shared_mem_release(rsa_workbuf);
}
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