drivers/char/tpm/eventlog/acpi.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2005 IBM Corporation
 *
 * Authors:
 *	Seiji Munetoh <munetoh@jp.ibm.com>
 *	Stefan Berger <stefanb@us.ibm.com>
 *	Reiner Sailer <sailer@watson.ibm.com>
 *	Kylene Hall <kjhall@us.ibm.com>
 *	Nayna Jain <nayna@linux.vnet.ibm.com>
 *
 * Maintained by: <tpmdd-devel@lists.sourceforge.net>
 *
 * Access to the event log extended by the TCG BIOS of PC platform
 */

#include <linux/seq_file.h>
#include <linux/fs.h>
#include <linux/security.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/tpm_eventlog.h>

#include "../tpm.h"
#include "common.h"

struct acpi_tcpa {
	struct acpi_table_header hdr;
	u16 platform_class;
	union {
		struct client_hdr {
			u32 log_max_len __packed;
			u64 log_start_addr __packed;
		} client;
		struct server_hdr {
			u16 reserved;
			u64 log_max_len __packed;
			u64 log_start_addr __packed;
		} server;
	};
};

/* Check that the given log is indeed a TPM2 log. */
static bool tpm_is_tpm2_log(void *bios_event_log, u64 len)
{
	struct tcg_efi_specid_event_head *efispecid;
	struct tcg_pcr_event *event_header;
	int n;

	if (len < sizeof(*event_header))
		return false;
	len -= sizeof(*event_header);
	event_header = bios_event_log;

	if (len < sizeof(*efispecid))
		return false;
	efispecid = (struct tcg_efi_specid_event_head *)event_header->event;

	n = memcmp(efispecid->signature, TCG_SPECID_SIG,
		   sizeof(TCG_SPECID_SIG));
	return n == 0;
}

/* read binary bios log */
int tpm_read_log_acpi(struct tpm_chip *chip)
{
	struct acpi_tcpa *buff;
	acpi_status status;
	void __iomem *virt;
	u64 len, start;
	struct tpm_bios_log *log;
	struct acpi_table_tpm2 *tbl;
	struct acpi_tpm2_phy *tpm2_phy;
	int format;
	int ret;

	log = &chip->log;

	/* Unfortuntely ACPI does not associate the event log with a specific
	 * TPM, like PPI. Thus all ACPI TPMs will read the same log.
	 */
	if (!chip->acpi_dev_handle)
		return -ENODEV;

	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
		status = acpi_get_table("TPM2", 1,
					(struct acpi_table_header **)&tbl);
		if (ACPI_FAILURE(status))
			return -ENODEV;

		if (tbl->header.length <
				sizeof(*tbl) + sizeof(struct acpi_tpm2_phy))
			return -ENODEV;

		tpm2_phy = (void *)tbl + sizeof(*tbl);
		len = tpm2_phy->log_area_minimum_length;

		start = tpm2_phy->log_area_start_address;
		if (!start || !len)
			return -ENODEV;

		format = EFI_TCG2_EVENT_LOG_FORMAT_TCG_2;
	} else {
		/* Find TCPA entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
		status = acpi_get_table(ACPI_SIG_TCPA, 1,
					(struct acpi_table_header **)&buff);
		if (ACPI_FAILURE(status))
			return -ENODEV;

		switch (buff->platform_class) {
		case BIOS_SERVER:
			len = buff->server.log_max_len;
			start = buff->server.log_start_addr;
			break;
		case BIOS_CLIENT:
		default:
			len = buff->client.log_max_len;
			start = buff->client.log_start_addr;
			break;
		}

		format = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
	}
	if (!len) {
		dev_warn(&chip->dev, "%s: TCPA log area empty\n", __func__);
		return -EIO;
	}

	/* malloc EventLog space */
	log->bios_event_log = kmalloc(len, GFP_KERNEL);
	if (!log->bios_event_log)
		return -ENOMEM;

	log->bios_event_log_end = log->bios_event_log + len;

	ret = -EIO;
	virt = acpi_os_map_iomem(start, len);
	if (!virt)
		goto err;

	memcpy_fromio(log->bios_event_log, virt, len);

	acpi_os_unmap_iomem(virt, len);

	if (chip->flags & TPM_CHIP_FLAG_TPM2 &&
	    !tpm_is_tpm2_log(log->bios_event_log, len)) {
		/* try EFI log next */
		ret = -ENODEV;
		goto err;
	}

	return format;

err:
	kfree(log->bios_event_log);
	log->bios_event_log = NULL;
	return ret;

}