xref: /linux/drivers/char/tpm/eventlog/tpm2.c (revision 4b4193256c8d3bc3a5397b5cd9494c2ad386317d)
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  */
calc_tpm2_event_size(struct tcg_pcr_event2_head * event,struct tcg_pcr_event * event_header)36 static 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 
tpm2_bios_measurements_start(struct seq_file * m,loff_t * pos)42 static 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 
tpm2_bios_measurements_next(struct seq_file * m,void * v,loff_t * pos)85 static 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 
tpm2_bios_measurements_stop(struct seq_file * m,void * v)124 static void tpm2_bios_measurements_stop(struct seq_file *m, void *v)
125 {
126 }
127 
tpm2_binary_bios_measurements_show(struct seq_file * m,void * v)128 static 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 
154 const 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