1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2016 IBM Corporation
4 *
5 * Authors:
6 *      Nayna Jain <nayna@linux.vnet.ibm.com>
7 *
8 * Access to TPM 2.0 event log as written by Firmware.
9 * It assumes that writer of event log has followed TCG Specification
10 * for Family "2.0" and written the event data in little endian.
11 * With that, it doesn't need any endian conversion for structure
12 * content.
13 */
14
15#include <linux/seq_file.h>
16#include <linux/fs.h>
17#include <linux/security.h>
18#include <linux/module.h>
19#include <linux/slab.h>
20#include <linux/tpm_eventlog.h>
21
22#include "../tpm.h"
23#include "common.h"
24
25/*
26 * calc_tpm2_event_size() - calculate the event size, where event
27 * is an entry in the TPM 2.0 event log. The event is of type Crypto
28 * Agile Log Entry Format as defined in TCG EFI Protocol Specification
29 * Family "2.0".
30
31 * @event: event whose size is to be calculated.
32 * @event_header: the first event in the event log.
33 *
34 * Returns size of the event. If it is an invalid event, returns 0.
35 */
36static size_t calc_tpm2_event_size(struct tcg_pcr_event2_head *event,
37				   struct tcg_pcr_event *event_header)
38{
39	return __calc_tpm2_event_size(event, event_header, false);
40}
41
42static void *tpm2_bios_measurements_start(struct seq_file *m, loff_t *pos)
43{
44	struct tpm_chip *chip = m->private;
45	struct tpm_bios_log *log = &chip->log;
46	void *addr = log->bios_event_log;
47	void *limit = log->bios_event_log_end;
48	struct tcg_pcr_event *event_header;
49	struct tcg_pcr_event2_head *event;
50	size_t size;
51	int i;
52
53	event_header = addr;
54	size = struct_size(event_header, event, event_header->event_size);
55
56	if (*pos == 0) {
57		if (addr + size < limit) {
58			if ((event_header->event_type == 0) &&
59			    (event_header->event_size == 0))
60				return NULL;
61			return SEQ_START_TOKEN;
62		}
63	}
64
65	if (*pos > 0) {
66		addr += size;
67		event = addr;
68		size = calc_tpm2_event_size(event, event_header);
69		if ((addr + size >=  limit) || (size == 0))
70			return NULL;
71	}
72
73	for (i = 0; i < (*pos - 1); i++) {
74		event = addr;
75		size = calc_tpm2_event_size(event, event_header);
76
77		if ((addr + size >= limit) || (size == 0))
78			return NULL;
79		addr += size;
80	}
81
82	return addr;
83}
84
85static void *tpm2_bios_measurements_next(struct seq_file *m, void *v,
86					 loff_t *pos)
87{
88	struct tcg_pcr_event *event_header;
89	struct tcg_pcr_event2_head *event;
90	struct tpm_chip *chip = m->private;
91	struct tpm_bios_log *log = &chip->log;
92	void *limit = log->bios_event_log_end;
93	size_t event_size;
94	void *marker;
95
96	(*pos)++;
97	event_header = log->bios_event_log;
98
99	if (v == SEQ_START_TOKEN) {
100		event_size = struct_size(event_header, event,
101					 event_header->event_size);
102		marker = event_header;
103	} else {
104		event = v;
105		event_size = calc_tpm2_event_size(event, event_header);
106		if (event_size == 0)
107			return NULL;
108		marker = event;
109	}
110
111	marker = marker + event_size;
112	if (marker >= limit)
113		return NULL;
114	v = marker;
115	event = v;
116
117	event_size = calc_tpm2_event_size(event, event_header);
118	if (((v + event_size) >= limit) || (event_size == 0))
119		return NULL;
120
121	return v;
122}
123
124static void tpm2_bios_measurements_stop(struct seq_file *m, void *v)
125{
126}
127
128static int tpm2_binary_bios_measurements_show(struct seq_file *m, void *v)
129{
130	struct tpm_chip *chip = m->private;
131	struct tpm_bios_log *log = &chip->log;
132	struct tcg_pcr_event *event_header = log->bios_event_log;
133	struct tcg_pcr_event2_head *event = v;
134	void *temp_ptr;
135	size_t size;
136
137	if (v == SEQ_START_TOKEN) {
138		size = struct_size(event_header, event,
139				   event_header->event_size);
140		temp_ptr = event_header;
141
142		if (size > 0)
143			seq_write(m, temp_ptr, size);
144	} else {
145		size = calc_tpm2_event_size(event, event_header);
146		temp_ptr = event;
147		if (size > 0)
148			seq_write(m, temp_ptr, size);
149	}
150
151	return 0;
152}
153
154const struct seq_operations tpm2_binary_b_measurements_seqops = {
155	.start = tpm2_bios_measurements_start,
156	.next = tpm2_bios_measurements_next,
157	.stop = tpm2_bios_measurements_stop,
158	.show = tpm2_binary_bios_measurements_show,
159};
160