acpi.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Copyright (C) 2005 IBM Corporation
  4 *
  5 * Authors:
  6 *	Seiji Munetoh <munetoh@jp.ibm.com>
  7 *	Stefan Berger <stefanb@us.ibm.com>
  8 *	Reiner Sailer <sailer@watson.ibm.com>
  9 *	Kylene Hall <kjhall@us.ibm.com>
 10 *	Nayna Jain <nayna@linux.vnet.ibm.com>
 11 *
 12 * Maintained by: <tpmdd-devel@lists.sourceforge.net>
 13 *
 14 * Access to the event log extended by the TCG BIOS of PC platform
 15 */
 16
 17#include <linux/device.h>
 18#include <linux/seq_file.h>
 19#include <linux/fs.h>
 20#include <linux/security.h>
 21#include <linux/module.h>
 22#include <linux/slab.h>
 23#include <linux/acpi.h>
 24#include <linux/tpm_eventlog.h>
 25
 26#include "../tpm.h"
 27#include "common.h"
 28
 29struct acpi_tcpa {
 30	struct acpi_table_header hdr;
 31	u16 platform_class;
 32	union {
 33		struct client_hdr {
 34			u32 log_max_len __packed;
 35			u64 log_start_addr __packed;
 36		} client;
 37		struct server_hdr {
 38			u16 reserved;
 39			u64 log_max_len __packed;
 40			u64 log_start_addr __packed;
 41		} server;
 42	};
 43};
 44
 45/* Check that the given log is indeed a TPM2 log. */
 46static bool tpm_is_tpm2_log(void *bios_event_log, u64 len)
 47{
 48	struct tcg_efi_specid_event_head *efispecid;
 49	struct tcg_pcr_event *event_header;
 50	int n;
 51
 52	if (len < sizeof(*event_header))
 53		return false;
 54	len -= sizeof(*event_header);
 55	event_header = bios_event_log;
 56
 57	if (len < sizeof(*efispecid))
 58		return false;
 59	efispecid = (struct tcg_efi_specid_event_head *)event_header->event;
 60
 61	n = memcmp(efispecid->signature, TCG_SPECID_SIG,
 62		   sizeof(TCG_SPECID_SIG));
 63	return n == 0;
 64}
 65
 66static void tpm_bios_log_free(void *data)
 67{
 68	kvfree(data);
 69}
 70
 71/* read binary bios log */
 72int tpm_read_log_acpi(struct tpm_chip *chip)
 73{
 74	struct acpi_tcpa *buff;
 75	acpi_status status;
 76	void __iomem *virt;
 77	u64 len, start;
 78	struct tpm_bios_log *log;
 79	struct acpi_table_tpm2 *tbl;
 80	struct acpi_tpm2_phy *tpm2_phy;
 81	int format;
 82	int ret;
 83
 84	log = &chip->log;
 85
 86	/* Unfortuntely ACPI does not associate the event log with a specific
 87	 * TPM, like PPI. Thus all ACPI TPMs will read the same log.
 88	 */
 89	if (!chip->acpi_dev_handle)
 90		return -ENODEV;
 91
 92	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
 93		status = acpi_get_table("TPM2", 1,
 94					(struct acpi_table_header **)&tbl);
 95		if (ACPI_FAILURE(status))
 96			return -ENODEV;
 97
 98		if (tbl->header.length <
 99				sizeof(*tbl) + sizeof(struct acpi_tpm2_phy)) {
100			acpi_put_table((struct acpi_table_header *)tbl);
101			return -ENODEV;
102		}
103
104		tpm2_phy = (void *)tbl + sizeof(*tbl);
105		len = tpm2_phy->log_area_minimum_length;
106
107		start = tpm2_phy->log_area_start_address;
108		if (!start || !len) {
109			acpi_put_table((struct acpi_table_header *)tbl);
110			return -ENODEV;
111		}
112
113		acpi_put_table((struct acpi_table_header *)tbl);
114		format = EFI_TCG2_EVENT_LOG_FORMAT_TCG_2;
115	} else {
116		/* Find TCPA entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
117		status = acpi_get_table(ACPI_SIG_TCPA, 1,
118					(struct acpi_table_header **)&buff);
119		if (ACPI_FAILURE(status))
120			return -ENODEV;
121
122		switch (buff->platform_class) {
123		case BIOS_SERVER:
124			len = buff->server.log_max_len;
125			start = buff->server.log_start_addr;
126			break;
127		case BIOS_CLIENT:
128		default:
129			len = buff->client.log_max_len;
130			start = buff->client.log_start_addr;
131			break;
132		}
133
134		acpi_put_table((struct acpi_table_header *)buff);
135		format = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
136	}
137
138	if (!len) {
139		dev_warn(&chip->dev, "%s: TCPA log area empty\n", __func__);
140		return -EIO;
141	}
142
143	/* malloc EventLog space */
144	log->bios_event_log = kvmalloc(len, GFP_KERNEL);
145	if (!log->bios_event_log)
146		return -ENOMEM;
147
148	log->bios_event_log_end = log->bios_event_log + len;
149
150	virt = acpi_os_map_iomem(start, len);
151	if (!virt) {
152		dev_warn(&chip->dev, "%s: Failed to map ACPI memory\n", __func__);
153		/* try EFI log next */
154		ret = -ENODEV;
155		goto err;
156	}
157
158	memcpy_fromio(log->bios_event_log, virt, len);
159
160	acpi_os_unmap_iomem(virt, len);
161
162	if (chip->flags & TPM_CHIP_FLAG_TPM2 &&
163	    !tpm_is_tpm2_log(log->bios_event_log, len)) {
164		/* try EFI log next */
165		ret = -ENODEV;
166		goto err;
167	}
168
169	ret = devm_add_action(&chip->dev, tpm_bios_log_free, log->bios_event_log);
170	if (ret) {
171		log->bios_event_log = NULL;
172		goto err;
173	}
174
175	return format;
176
177err:
178	tpm_bios_log_free(log->bios_event_log);
179	log->bios_event_log = NULL;
180	return ret;
181}