aboutsummaryrefslogtreecommitdiff
path: root/drivers/char/tpm/eventlog/tpm2.c
blob: f824563fc28dd091303f89de651589ea5350a64b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
/*
 * Copyright (C) 2016 IBM Corporation
 *
 * Authors:
 *      Nayna Jain <nayna@linux.vnet.ibm.com>
 *
 * Access to TPM 2.0 event log as written by Firmware.
 * It assumes that writer of event log has followed TCG Specification
 * for Family "2.0" and written the event data in little endian.
 * With that, it doesn't need any endian conversion for structure
 * content.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

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

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

/*
 * calc_tpm2_event_size() - calculate the event size, where event
 * is an entry in the TPM 2.0 event log. The event is of type Crypto
 * Agile Log Entry Format as defined in TCG EFI Protocol Specification
 * Family "2.0".

 * @event: event whose size is to be calculated.
 * @event_header: the first event in the event log.
 *
 * Returns size of the event. If it is an invalid event, returns 0.
 */
static size_t calc_tpm2_event_size(struct tcg_pcr_event2_head *event,
				   struct tcg_pcr_event *event_header)
{
	struct tcg_efi_specid_event_head *efispecid;
	struct tcg_event_field *event_field;
	void *marker;
	void *marker_start;
	u32 halg_size;
	size_t size;
	u16 halg;
	int i;
	int j;

	marker = event;
	marker_start = marker;
	marker = marker + sizeof(event->pcr_idx) + sizeof(event->event_type)
		+ sizeof(event->count);

	efispecid = (struct tcg_efi_specid_event_head *)event_header->event;

	/* Check if event is malformed. */
	if (event->count > efispecid->num_algs)
		return 0;

	for (i = 0; i < event->count; i++) {
		halg_size = sizeof(event->digests[i].alg_id);
		memcpy(&halg, marker, halg_size);
		marker = marker + halg_size;
		for (j = 0; j < efispecid->num_algs; j++) {
			if (halg == efispecid->digest_sizes[j].alg_id) {
				marker +=
					efispecid->digest_sizes[j].digest_size;
				break;
			}
		}
		/* Algorithm without known length. Such event is unparseable. */
		if (j == efispecid->num_algs)
			return 0;
	}

	event_field = (struct tcg_event_field *)marker;
	marker = marker + sizeof(event_field->event_size)
		+ event_field->event_size;
	size = marker - marker_start;

	if ((event->event_type == 0) && (event_field->event_size == 0))
		return 0;

	return size;
}

static void *tpm2_bios_measurements_start(struct seq_file *m, loff_t *pos)
{
	struct tpm_chip *chip = m->private;
	struct tpm_bios_log *log = &chip->log;
	void *addr = log->bios_event_log;
	void *limit = log->bios_event_log_end;
	struct tcg_pcr_event *event_header;
	struct tcg_pcr_event2_head *event;
	size_t size;
	int i;

	event_header = addr;
	size = sizeof(struct tcg_pcr_event) - sizeof(event_header->event)
		+ event_header->event_size;

	if (*pos == 0) {
		if (addr + size < limit) {
			if ((event_header->event_type == 0) &&
			    (event_header->event_size == 0))
				return NULL;
			return SEQ_START_TOKEN;
		}
	}

	if (*pos > 0) {
		addr += size;
		event = addr;
		size = calc_tpm2_event_size(event, event_header);
		if ((addr + size >=  limit) || (size == 0))
			return NULL;
	}

	for (i = 0; i < (*pos - 1); i++) {
		event = addr;
		size = calc_tpm2_event_size(event, event_header);

		if ((addr + size >= limit) || (size == 0))
			return NULL;
		addr += size;
	}

	return addr;
}

static void *tpm2_bios_measurements_next(struct seq_file *m, void *v,
					 loff_t *pos)
{
	struct tcg_pcr_event *event_header;
	struct tcg_pcr_event2_head *event;
	struct tpm_chip *chip = m->private;
	struct tpm_bios_log *log = &chip->log;
	void *limit = log->bios_event_log_end;
	size_t event_size;
	void *marker;

	event_header = log->bios_event_log;

	if (v == SEQ_START_TOKEN) {
		event_size = sizeof(struct tcg_pcr_event) -
			sizeof(event_header->event) + event_header->event_size;
		marker = event_header;
	} else {
		event = v;
		event_size = calc_tpm2_event_size(event, event_header);
		if (event_size == 0)
			return NULL;
		marker = event;
	}

	marker = marker + event_size;
	if (marker >= limit)
		return NULL;
	v = marker;
	event = v;

	event_size = calc_tpm2_event_size(event, event_header);
	if (((v + event_size) >= limit) || (event_size == 0))
		return NULL;

	(*pos)++;
	return v;
}

static void tpm2_bios_measurements_stop(struct seq_file *m, void *v)
{
}

static int tpm2_binary_bios_measurements_show(struct seq_file *m, void *v)
{
	struct tpm_chip *chip = m->private;
	struct tpm_bios_log *log = &chip->log;
	struct tcg_pcr_event *event_header = log->bios_event_log;
	struct tcg_pcr_event2_head *event = v;
	void *temp_ptr;
	size_t size;

	if (v == SEQ_START_TOKEN) {
		size = sizeof(struct tcg_pcr_event) -
			sizeof(event_header->event) + event_header->event_size;

		temp_ptr = event_header;

		if (size > 0)
			seq_write(m, temp_ptr, size);
	} else {
		size = calc_tpm2_event_size(event, event_header);
		temp_ptr = event;
		if (size > 0)
			seq_write(m, temp_ptr, size);
	}

	return 0;
}

const struct seq_operations tpm2_binary_b_measurements_seqops = {
	.start = tpm2_bios_measurements_start,
	.next = tpm2_bios_measurements_next,
	.stop = tpm2_bios_measurements_stop,
	.show = tpm2_binary_bios_measurements_show,
};