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
66/* read binary bios log */
67int tpm_read_log_acpi(struct tpm_chip *chip)
68{
69	struct acpi_tcpa *buff;
70	acpi_status status;
71	void __iomem *virt;
72	u64 len, start;
73	struct tpm_bios_log *log;
74	struct acpi_table_tpm2 *tbl;
75	struct acpi_tpm2_phy *tpm2_phy;
76	int format;
77	int ret;
78
79	log = &chip->log;
80
81	/* Unfortuntely ACPI does not associate the event log with a specific
82	 * TPM, like PPI. Thus all ACPI TPMs will read the same log.
83	 */
84	if (!chip->acpi_dev_handle)
85		return -ENODEV;
86
87	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
88		status = acpi_get_table("TPM2", 1,
89					(struct acpi_table_header **)&tbl);
90		if (ACPI_FAILURE(status))
91			return -ENODEV;
92
93		if (tbl->header.length <
94				sizeof(*tbl) + sizeof(struct acpi_tpm2_phy)) {
95			acpi_put_table((struct acpi_table_header *)tbl);
96			return -ENODEV;
97		}
98
99		tpm2_phy = (void *)tbl + sizeof(*tbl);
100		len = tpm2_phy->log_area_minimum_length;
101
102		start = tpm2_phy->log_area_start_address;
103		if (!start || !len) {
104			acpi_put_table((struct acpi_table_header *)tbl);
105			return -ENODEV;
106		}
107
108		acpi_put_table((struct acpi_table_header *)tbl);
109		format = EFI_TCG2_EVENT_LOG_FORMAT_TCG_2;
110	} else {
111		/* Find TCPA entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
112		status = acpi_get_table(ACPI_SIG_TCPA, 1,
113					(struct acpi_table_header **)&buff);
114		if (ACPI_FAILURE(status))
115			return -ENODEV;
116
117		switch (buff->platform_class) {
118		case BIOS_SERVER:
119			len = buff->server.log_max_len;
120			start = buff->server.log_start_addr;
121			break;
122		case BIOS_CLIENT:
123		default:
124			len = buff->client.log_max_len;
125			start = buff->client.log_start_addr;
126			break;
127		}
128
129		acpi_put_table((struct acpi_table_header *)buff);
130		format = EFI_TCG2_EVENT_LOG_FORMAT_TCG_1_2;
131	}
132
133	if (!len) {
134		dev_warn(&chip->dev, "%s: TCPA log area empty\n", __func__);
135		return -EIO;
136	}
137
138	/* malloc EventLog space */
139	log->bios_event_log = devm_kmalloc(&chip->dev, len, GFP_KERNEL);
140	if (!log->bios_event_log)
141		return -ENOMEM;
142
143	log->bios_event_log_end = log->bios_event_log + len;
144
145	ret = -EIO;
146	virt = acpi_os_map_iomem(start, len);
147	if (!virt) {
148		dev_warn(&chip->dev, "%s: Failed to map ACPI memory\n", __func__);
149		/* try EFI log next */
150		ret = -ENODEV;
151		goto err;
152	}
153
154	memcpy_fromio(log->bios_event_log, virt, len);
155
156	acpi_os_unmap_iomem(virt, len);
157
158	if (chip->flags & TPM_CHIP_FLAG_TPM2 &&
159	    !tpm_is_tpm2_log(log->bios_event_log, len)) {
160		/* try EFI log next */
161		ret = -ENODEV;
162		goto err;
163	}
164
165	return format;
166
167err:
168	devm_kfree(&chip->dev, log->bios_event_log);
169	log->bios_event_log = NULL;
170	return ret;
171}
172