efi.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Copyright (C) 2017 Google
  4 *
  5 * Authors:
  6 *      Thiebaud Weksteen <tweek@google.com>
  7 */
  8
  9#include <linux/device.h>
 10#include <linux/efi.h>
 11#include <linux/tpm_eventlog.h>
 12
 13#include "../tpm.h"
 14#include "common.h"
 15
 16/* read binary bios log from EFI configuration table */
 17int tpm_read_log_efi(struct tpm_chip *chip)
 18{
 19
 20	struct efi_tcg2_final_events_table *final_tbl = NULL;
 21	int final_events_log_size = efi_tpm_final_log_size;
 22	struct linux_efi_tpm_eventlog *log_tbl;
 23	struct tpm_bios_log *log;
 24	u32 log_size;
 25	u8 tpm_log_version;
 26	void *tmp;
 27	int ret;
 28
 29	if (!(chip->flags & TPM_CHIP_FLAG_TPM2))
 30		return -ENODEV;
 31
 32	if (efi.tpm_log == EFI_INVALID_TABLE_ADDR)
 33		return -ENODEV;
 34
 35	log = &chip->log;
 36
 37	log_tbl = memremap(efi.tpm_log, sizeof(*log_tbl), MEMREMAP_WB);
 38	if (!log_tbl) {
 39		pr_err("Could not map UEFI TPM log table !\n");
 40		return -ENOMEM;
 41	}
 42
 43	log_size = log_tbl->size;
 44	memunmap(log_tbl);
 45
 46	if (!log_size) {
 47		pr_warn("UEFI TPM log area empty\n");
 48		return -EIO;
 49	}
 50
 51	log_tbl = memremap(efi.tpm_log, sizeof(*log_tbl) + log_size,
 52			   MEMREMAP_WB);
 53	if (!log_tbl) {
 54		pr_err("Could not map UEFI TPM log table payload!\n");
 55		return -ENOMEM;
 56	}
 57
 58	/* malloc EventLog space */
 59	log->bios_event_log = devm_kmemdup(&chip->dev, log_tbl->log, log_size, GFP_KERNEL);
 60	if (!log->bios_event_log) {
 61		ret = -ENOMEM;
 62		goto out;
 63	}
 64
 65	log->bios_event_log_end = log->bios_event_log + log_size;
 66	tpm_log_version = log_tbl->version;
 67
 68	ret = tpm_log_version;
 69
 70	if (efi.tpm_final_log == EFI_INVALID_TABLE_ADDR ||
 71	    final_events_log_size == 0 ||
 72	    tpm_log_version != EFI_TCG2_EVENT_LOG_FORMAT_TCG_2)
 73		goto out;
 74
 75	final_tbl = memremap(efi.tpm_final_log,
 76			     sizeof(*final_tbl) + final_events_log_size,
 77			     MEMREMAP_WB);
 78	if (!final_tbl) {
 79		pr_err("Could not map UEFI TPM final log\n");
 80		devm_kfree(&chip->dev, log->bios_event_log);
 81		ret = -ENOMEM;
 82		goto out;
 83	}
 84
 85	/*
 86	 * The 'final events log' size excludes the 'final events preboot log'
 87	 * at its beginning.
 88	 */
 89	final_events_log_size -= log_tbl->final_events_preboot_size;
 90
 91	/*
 92	 * Allocate memory for the 'combined log' where we will append the
 93	 * 'final events log' to.
 94	 */
 95	tmp = devm_krealloc(&chip->dev, log->bios_event_log,
 96			    log_size + final_events_log_size,
 97			    GFP_KERNEL);
 98	if (!tmp) {
 99		devm_kfree(&chip->dev, log->bios_event_log);
100		ret = -ENOMEM;
101		goto out;
102	}
103
104	log->bios_event_log = tmp;
105
106	/*
107	 * Append any of the 'final events log' that didn't also end up in the
108	 * 'main log'. Events can be logged in both if events are generated
109	 * between GetEventLog() and ExitBootServices().
110	 */
111	memcpy((void *)log->bios_event_log + log_size,
112	       final_tbl->events + log_tbl->final_events_preboot_size,
113	       final_events_log_size);
114	/*
115	 * The size of the 'combined log' is the size of the 'main log' plus
116	 * the size of the 'final events log'.
117	 */
118	log->bios_event_log_end = log->bios_event_log +
119		log_size + final_events_log_size;
120
121out:
122	memunmap(final_tbl);
123	memunmap(log_tbl);
124	return ret;
125}