566 lines
13 KiB
C
566 lines
13 KiB
C
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/* Copyright 2017 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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/* Rollback protection logic. */
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#include "common.h"
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#include "console.h"
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#include "cryptoc/util.h"
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#include "flash.h"
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#include "hooks.h"
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#include "host_command.h"
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#ifdef CONFIG_MPU
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#include "mpu.h"
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#endif
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#include "rollback.h"
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#include "sha256.h"
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#include "system.h"
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#include "task.h"
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#include "trng.h"
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#include "util.h"
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/* Console output macros */
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#define CPRINTS(format, args...) cprints(CC_SYSTEM, format, ## args)
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/* Number of rollback regions */
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#define ROLLBACK_REGIONS 2
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/*
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* Note: Do not change this structure without also updating
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* common/firmware_image.S .image.ROLLBACK section.
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*/
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struct rollback_data {
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int32_t id; /* Incrementing number to indicate which region to use. */
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int32_t rollback_min_version;
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#ifdef CONFIG_ROLLBACK_SECRET_SIZE
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uint8_t secret[CONFIG_ROLLBACK_SECRET_SIZE];
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#endif
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/* cookie must always be last, as it validates the rest of the data. */
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uint32_t cookie;
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};
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static int get_rollback_offset(int region)
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{
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#ifdef CONFIG_FLASH_MULTIPLE_REGION
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int rv;
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int rollback_start_bank = flash_bank_index(CONFIG_ROLLBACK_OFF);
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rv = flash_bank_start_offset(rollback_start_bank + region);
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ASSERT(rv >= 0);
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return rv;
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#else
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return CONFIG_ROLLBACK_OFF + region * CONFIG_FLASH_ERASE_SIZE;
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#endif
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}
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#ifdef SECTION_IS_RO
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static int get_rollback_erase_size_bytes(int region)
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{
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int erase_size;
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#ifndef CONFIG_FLASH_MULTIPLE_REGION
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erase_size = CONFIG_FLASH_ERASE_SIZE;
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#else
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int rollback_start_bank = flash_bank_index(CONFIG_ROLLBACK_OFF);
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erase_size = flash_bank_erase_size(rollback_start_bank + region);
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#endif
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ASSERT(erase_size > 0);
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ASSERT(ROLLBACK_REGIONS * erase_size <= CONFIG_ROLLBACK_SIZE);
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ASSERT(sizeof(struct rollback_data) <= erase_size);
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return erase_size;
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}
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#endif
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/*
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* When MPU is available, read rollback with interrupts disabled, to minimize
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* time protection is left open.
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*/
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static void lock_rollback(void)
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{
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#ifdef CONFIG_ROLLBACK_MPU_PROTECT
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mpu_lock_rollback(1);
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interrupt_enable();
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#endif
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}
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static void unlock_rollback(void)
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{
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#ifdef CONFIG_ROLLBACK_MPU_PROTECT
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interrupt_disable();
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mpu_lock_rollback(0);
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#endif
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}
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static void clear_rollback(struct rollback_data *data)
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{
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#ifdef CONFIG_ROLLBACK_SECRET_SIZE
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always_memset(data->secret, 0, sizeof(data->secret));
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#endif
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}
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static int read_rollback(int region, struct rollback_data *data)
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{
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int offset;
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int ret = EC_SUCCESS;
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offset = get_rollback_offset(region);
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unlock_rollback();
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if (flash_read(offset, sizeof(*data), (char *)data))
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ret = EC_ERROR_UNKNOWN;
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lock_rollback();
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return ret;
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}
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/*
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* Get the most recent rollback information.
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*
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* @data: Returns most recent rollback data block. The data is filled
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* with zeros if no valid rollback block is present
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*
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* Return most recent region index on success (>= 0, or 0 if no rollback
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* region is valid), negative value on error.
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*/
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static int get_latest_rollback(struct rollback_data *data)
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{
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int ret = -1;
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int region;
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int min_region = -1;
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int max_id = -1;
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struct rollback_data tmp_data;
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for (region = 0; region < ROLLBACK_REGIONS; region++) {
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if (read_rollback(region, &tmp_data))
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goto failed;
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/* Check if not initialized or invalid cookie. */
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if (tmp_data.cookie != CROS_EC_ROLLBACK_COOKIE)
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continue;
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if (tmp_data.id > max_id) {
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min_region = region;
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max_id = tmp_data.id;
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}
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}
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if (min_region >= 0) {
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if (read_rollback(min_region, data))
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goto failed;
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} else {
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min_region = 0;
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clear_rollback(data);
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}
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ret = min_region;
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failed:
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clear_rollback(&tmp_data);
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return ret;
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}
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int32_t rollback_get_minimum_version(void)
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{
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struct rollback_data data;
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int32_t ret = -1;
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if (get_latest_rollback(&data) < 0)
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goto failed;
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ret = data.rollback_min_version;
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failed:
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clear_rollback(&data);
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return ret;
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}
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#ifdef CONFIG_ROLLBACK_SECRET_SIZE
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test_mockable int rollback_get_secret(uint8_t *secret)
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{
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int ret = EC_ERROR_UNKNOWN;
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struct rollback_data data;
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uint8_t first;
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int i = 0;
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if (get_latest_rollback(&data) < 0)
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goto failed;
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/* Check that secret is not full of 0x00 or 0xff */
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first = data.secret[0];
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if (first == 0x00 || first == 0xff) {
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for (i = 1; i < sizeof(data.secret); i++) {
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if (data.secret[i] != first)
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goto good;
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}
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goto failed;
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}
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good:
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memcpy(secret, data.secret, sizeof(data.secret));
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ret = EC_SUCCESS;
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failed:
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clear_rollback(&data);
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return ret;
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}
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#endif
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int rollback_lock(void)
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{
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int ret;
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/* Already locked */
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if (flash_get_protect() & EC_FLASH_PROTECT_ROLLBACK_NOW)
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return EC_SUCCESS;
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CPRINTS("Protecting rollback");
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/* This may do nothing if WP is not enabled, or RO is not protected. */
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ret = flash_set_protect(EC_FLASH_PROTECT_ROLLBACK_AT_BOOT, -1);
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if (!(flash_get_protect() & EC_FLASH_PROTECT_ROLLBACK_NOW) &&
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flash_get_protect() & EC_FLASH_PROTECT_ROLLBACK_AT_BOOT) {
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/*
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* If flash protection is still not enabled (some chips may
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* be able to enable it immediately), reboot.
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*/
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cflush();
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system_reset(SYSTEM_RESET_HARD | SYSTEM_RESET_PRESERVE_FLAGS);
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}
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return ret;
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}
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#ifdef CONFIG_ROLLBACK_UPDATE
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#ifdef CONFIG_ROLLBACK_SECRET_SIZE
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static int add_entropy(uint8_t *dst, const uint8_t *src,
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uint8_t *add, unsigned int add_len)
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{
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int ret = 0;
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#ifdef CONFIG_SHA256
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BUILD_ASSERT(SHA256_DIGEST_SIZE == CONFIG_ROLLBACK_SECRET_SIZE);
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struct sha256_ctx ctx;
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uint8_t *hash;
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#ifdef CONFIG_ROLLBACK_SECRET_LOCAL_ENTROPY_SIZE
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uint8_t extra;
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int i;
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#endif
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SHA256_init(&ctx);
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SHA256_update(&ctx, src, CONFIG_ROLLBACK_SECRET_SIZE);
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SHA256_update(&ctx, add, add_len);
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#ifdef CONFIG_ROLLBACK_SECRET_LOCAL_ENTROPY_SIZE
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/* Add some locally produced entropy */
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for (i = 0; i < CONFIG_ROLLBACK_SECRET_LOCAL_ENTROPY_SIZE; i++) {
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if (!board_get_entropy(&extra, 1))
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goto failed;
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SHA256_update(&ctx, &extra, 1);
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}
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#endif
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hash = SHA256_final(&ctx);
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memcpy(dst, hash, CONFIG_ROLLBACK_SECRET_SIZE);
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ret = 1;
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#ifdef CONFIG_ROLLBACK_SECRET_LOCAL_ENTROPY_SIZE
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failed:
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#endif
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always_memset(&ctx, 0, sizeof(ctx));
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#else
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#error "Adding entropy to secret in rollback region requires SHA256."
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#endif
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return ret;
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}
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#endif /* CONFIG_ROLLBACK_SECRET_SIZE */
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/**
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* Update rollback block.
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*
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* @param next_min_version Minimum version to update in rollback block. Can
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* be a negative value if entropy is provided (in
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* that case the current minimum version is kept).
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* @param entropy Entropy to be added to rollback block secret
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* (can be NULL, in that case no entropy is added).
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* @param len entropy length
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*
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* @return EC_SUCCESS on success, EC_ERROR_* on error.
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*/
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static int rollback_update(int32_t next_min_version,
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uint8_t *entropy, unsigned int length)
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{
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/*
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* When doing flash_write operation, the data needs to be in blocks
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* of CONFIG_FLASH_WRITE_SIZE, pad rollback_data as required.
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*/
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uint8_t block[CONFIG_FLASH_WRITE_SIZE *
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DIV_ROUND_UP(sizeof(struct rollback_data),
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CONFIG_FLASH_WRITE_SIZE)];
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struct rollback_data *data = (struct rollback_data *)block;
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BUILD_ASSERT(sizeof(block) >= sizeof(*data));
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int erase_size, offset, region, ret;
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if (flash_get_protect() & EC_FLASH_PROTECT_ROLLBACK_NOW) {
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ret = EC_ERROR_ACCESS_DENIED;
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goto out;
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}
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|
|
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/* Initialize the rest of the block. */
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memset(&block[sizeof(*data)], 0xff, sizeof(block)-sizeof(*data));
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region = get_latest_rollback(data);
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|
|
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if (region < 0) {
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ret = EC_ERROR_UNKNOWN;
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goto out;
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}
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|
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#ifdef CONFIG_ROLLBACK_SECRET_SIZE
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if (entropy) {
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/* Do not accept to decrease the value. */
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if (next_min_version < data->rollback_min_version)
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next_min_version = data->rollback_min_version;
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} else
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#endif
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{
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/* Do not accept to decrease the value. */
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if (next_min_version < data->rollback_min_version) {
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|
ret = EC_ERROR_INVAL;
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goto out;
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}
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|
|
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/* No need to update if version is already correct. */
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if (next_min_version == data->rollback_min_version) {
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ret = EC_SUCCESS;
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goto out;
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}
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}
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|
|
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/* Use the other region. */
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region = (region + 1) % ROLLBACK_REGIONS;
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offset = get_rollback_offset(region);
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|
|
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data->id = data->id + 1;
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data->rollback_min_version = next_min_version;
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#ifdef CONFIG_ROLLBACK_SECRET_SIZE
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/*
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|
* If we are provided with some entropy, add it to secret. Otherwise,
|
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* data.secret is left untouched and written back to the other region.
|
||
|
*/
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if (entropy) {
|
||
|
if (!add_entropy(data->secret, data->secret, entropy, length)) {
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|
ret = EC_ERROR_UNCHANGED;
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goto out;
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|
}
|
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|
}
|
||
|
#endif
|
||
|
data->cookie = CROS_EC_ROLLBACK_COOKIE;
|
||
|
|
||
|
erase_size = get_rollback_erase_size_bytes(region);
|
||
|
|
||
|
if (erase_size < 0) {
|
||
|
ret = EC_ERROR_UNKNOWN;
|
||
|
goto out;
|
||
|
}
|
||
|
|
||
|
/* Offset should never be part of active image. */
|
||
|
if (system_unsafe_to_overwrite(offset, erase_size)) {
|
||
|
ret = EC_ERROR_UNKNOWN;
|
||
|
goto out;
|
||
|
}
|
||
|
|
||
|
if (flash_erase(offset, erase_size)) {
|
||
|
ret = EC_ERROR_UNKNOWN;
|
||
|
goto out;
|
||
|
}
|
||
|
|
||
|
unlock_rollback();
|
||
|
ret = flash_write(offset, sizeof(block), block);
|
||
|
lock_rollback();
|
||
|
|
||
|
out:
|
||
|
clear_rollback(data);
|
||
|
return ret;
|
||
|
}
|
||
|
|
||
|
int rollback_update_version(int32_t next_min_version)
|
||
|
{
|
||
|
return rollback_update(next_min_version, NULL, 0);
|
||
|
}
|
||
|
|
||
|
int rollback_add_entropy(uint8_t *data, unsigned int len)
|
||
|
{
|
||
|
return rollback_update(-1, data, len);
|
||
|
}
|
||
|
|
||
|
static int command_rollback_update(int argc, char **argv)
|
||
|
{
|
||
|
int32_t min_version;
|
||
|
char *e;
|
||
|
|
||
|
if (argc < 2)
|
||
|
return EC_ERROR_PARAM_COUNT;
|
||
|
|
||
|
min_version = strtoi(argv[1], &e, 0);
|
||
|
|
||
|
if (*e || min_version < 0)
|
||
|
return EC_ERROR_PARAM1;
|
||
|
|
||
|
return rollback_update_version(min_version);
|
||
|
}
|
||
|
DECLARE_CONSOLE_COMMAND(rollbackupdate, command_rollback_update,
|
||
|
"min_version",
|
||
|
"Update rollback info");
|
||
|
|
||
|
#ifdef CONFIG_ROLLBACK_SECRET_SIZE
|
||
|
static int command_rollback_add_entropy(int argc, char **argv)
|
||
|
{
|
||
|
int len;
|
||
|
|
||
|
if (argc < 2)
|
||
|
return EC_ERROR_PARAM_COUNT;
|
||
|
|
||
|
len = strlen(argv[1]);
|
||
|
|
||
|
return rollback_add_entropy(argv[1], len);
|
||
|
}
|
||
|
DECLARE_CONSOLE_COMMAND(rollbackaddent, command_rollback_add_entropy,
|
||
|
"data",
|
||
|
"Add entropy to rollback block");
|
||
|
|
||
|
#ifdef CONFIG_RNG
|
||
|
static int add_entropy_action;
|
||
|
static int add_entropy_rv = EC_RES_UNAVAILABLE;
|
||
|
|
||
|
static void add_entropy_deferred(void)
|
||
|
{
|
||
|
uint8_t rand[CONFIG_ROLLBACK_SECRET_SIZE];
|
||
|
int repeat = 1;
|
||
|
|
||
|
/*
|
||
|
* If asked to reset the old secret, just add entropy multiple times,
|
||
|
* which will ping-pong between the blocks.
|
||
|
*/
|
||
|
if (add_entropy_action == ADD_ENTROPY_RESET_ASYNC)
|
||
|
repeat = ROLLBACK_REGIONS;
|
||
|
|
||
|
init_trng();
|
||
|
do {
|
||
|
rand_bytes(rand, sizeof(rand));
|
||
|
if (rollback_add_entropy(rand, sizeof(rand)) != EC_SUCCESS) {
|
||
|
add_entropy_rv = EC_RES_ERROR;
|
||
|
goto out;
|
||
|
}
|
||
|
} while (--repeat);
|
||
|
|
||
|
add_entropy_rv = EC_RES_SUCCESS;
|
||
|
out:
|
||
|
exit_trng();
|
||
|
}
|
||
|
DECLARE_DEFERRED(add_entropy_deferred);
|
||
|
|
||
|
static enum ec_status
|
||
|
hc_rollback_add_entropy(struct host_cmd_handler_args *args)
|
||
|
{
|
||
|
const struct ec_params_rollback_add_entropy *p = args->params;
|
||
|
|
||
|
switch (p->action) {
|
||
|
case ADD_ENTROPY_ASYNC:
|
||
|
case ADD_ENTROPY_RESET_ASYNC:
|
||
|
if (add_entropy_rv == EC_RES_BUSY)
|
||
|
return EC_RES_BUSY;
|
||
|
|
||
|
add_entropy_action = p->action;
|
||
|
add_entropy_rv = EC_RES_BUSY;
|
||
|
hook_call_deferred(&add_entropy_deferred_data, 0);
|
||
|
|
||
|
return EC_RES_SUCCESS;
|
||
|
|
||
|
case ADD_ENTROPY_GET_RESULT:
|
||
|
return add_entropy_rv;
|
||
|
}
|
||
|
|
||
|
return EC_RES_INVALID_PARAM;
|
||
|
}
|
||
|
DECLARE_HOST_COMMAND(EC_CMD_ADD_ENTROPY,
|
||
|
hc_rollback_add_entropy,
|
||
|
EC_VER_MASK(0));
|
||
|
#endif /* CONFIG_RNG */
|
||
|
#endif /* CONFIG_ROLLBACK_SECRET_SIZE */
|
||
|
#endif /* CONFIG_ROLLBACK_UPDATE */
|
||
|
|
||
|
static int command_rollback_info(int argc, char **argv)
|
||
|
{
|
||
|
int ret = EC_ERROR_UNKNOWN;
|
||
|
int region, min_region;
|
||
|
int32_t rw_rollback_version;
|
||
|
struct rollback_data data;
|
||
|
|
||
|
min_region = get_latest_rollback(&data);
|
||
|
|
||
|
if (min_region < 0)
|
||
|
goto failed;
|
||
|
|
||
|
rw_rollback_version = system_get_rollback_version(SYSTEM_IMAGE_RW);
|
||
|
|
||
|
ccprintf("rollback minimum version: %d\n", data.rollback_min_version);
|
||
|
ccprintf("RW rollback version: %d\n", rw_rollback_version);
|
||
|
|
||
|
for (region = 0; region < ROLLBACK_REGIONS; region++) {
|
||
|
ret = read_rollback(region, &data);
|
||
|
if (ret)
|
||
|
goto failed;
|
||
|
|
||
|
ccprintf("rollback %d: %08x %08x %08x",
|
||
|
region, data.id, data.rollback_min_version,
|
||
|
data.cookie);
|
||
|
#ifdef CONFIG_ROLLBACK_SECRET_SIZE
|
||
|
if (!system_is_locked()) {
|
||
|
/* If system is unlocked, show some of the secret. */
|
||
|
ccprintf(" [%02x..%02x]", data.secret[0],
|
||
|
data.secret[CONFIG_ROLLBACK_SECRET_SIZE-1]);
|
||
|
}
|
||
|
#endif
|
||
|
if (min_region == region)
|
||
|
ccprintf(" *");
|
||
|
ccprintf("\n");
|
||
|
}
|
||
|
ret = EC_SUCCESS;
|
||
|
|
||
|
failed:
|
||
|
clear_rollback(&data);
|
||
|
return ret;
|
||
|
}
|
||
|
DECLARE_SAFE_CONSOLE_COMMAND(rollbackinfo, command_rollback_info,
|
||
|
NULL,
|
||
|
"Print rollback info");
|
||
|
|
||
|
static enum ec_status
|
||
|
host_command_rollback_info(struct host_cmd_handler_args *args)
|
||
|
{
|
||
|
int ret = EC_RES_UNAVAILABLE;
|
||
|
struct ec_response_rollback_info *r = args->response;
|
||
|
int min_region;
|
||
|
struct rollback_data data;
|
||
|
|
||
|
min_region = get_latest_rollback(&data);
|
||
|
|
||
|
if (min_region < 0)
|
||
|
goto failed;
|
||
|
|
||
|
r->id = data.id;
|
||
|
r->rollback_min_version = data.rollback_min_version;
|
||
|
r->rw_rollback_version = system_get_rollback_version(SYSTEM_IMAGE_RW);
|
||
|
|
||
|
args->response_size = sizeof(*r);
|
||
|
ret = EC_RES_SUCCESS;
|
||
|
|
||
|
failed:
|
||
|
clear_rollback(&data);
|
||
|
return ret;
|
||
|
}
|
||
|
DECLARE_HOST_COMMAND(EC_CMD_ROLLBACK_INFO,
|
||
|
host_command_rollback_info,
|
||
|
EC_VER_MASK(0));
|