1/*-
2 * Copyright (c) 2018, Juniper Networks, Inc.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
14 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
15 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
16 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
17 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
18 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
19 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25#include <sys/cdefs.h>
26#include <sys/queue.h>
27#include "libsecureboot-priv.h"
28
29/*
30 * To support measured boot without putting a ton
31 * of extra code in the loader, we just maintain
32 * a hash of all the hashes we (attempt to) verify.
33 * The loader can export this for kernel or rc script
34 * to feed to a TPM pcr register - hence the name ve_pcr.
35 *
36 * NOTE: in the current standard the TPM pcr register size is for SHA1,
37 * the fact that we provide a SHA256 hash should not matter
38 * as long as we are consistent - it can be truncated or hashed
39 * before feeding to TPM.
40 */
41
42static const br_hash_class *pcr_md = NULL;
43static br_hash_compat_context pcr_ctx;
44static size_t pcr_hlen = 0;
45static int pcr_updating = -1;
46
47struct hashed_info {
48	const char *hi_path;
49	const char *hi_basename;
50	STAILQ_ENTRY(hashed_info) entries;
51};
52
53static STAILQ_HEAD(, hashed_info) hi_list;
54
55
56/**
57 * @brief initialize pcr context
58 *
59 * Real TPM registers only hold a SHA1 hash
60 * but we use SHA256
61 */
62void
63ve_pcr_init(void)
64{
65	if (pcr_updating < 0) {
66		pcr_updating = 0;
67		pcr_hlen = br_sha256_SIZE;
68		pcr_md = &br_sha256_vtable;
69		pcr_md->init(&pcr_ctx.vtable);
70		STAILQ_INIT(&hi_list);
71	}
72}
73
74/**
75 * @brief get pcr_updating state
76 */
77int
78ve_pcr_updating_get(void)
79{
80	return (pcr_updating);
81}
82
83/**
84 * @brief set pcr_updating state
85 */
86void
87ve_pcr_updating_set(int updating)
88{
89	pcr_updating = updating;
90}
91
92/**
93 * @brief update pcr context
94 */
95void
96ve_pcr_update(const char *path, unsigned char *data, size_t dlen)
97{
98	struct hashed_info *hip;
99
100	if (pcr_updating > 0 && pcr_md != NULL) {
101		pcr_md->update(&pcr_ctx.vtable, data, dlen);
102		/* if mallocs fail, measured boot will likely fail too */
103		if ((hip = malloc(sizeof(struct hashed_info)))) {
104			hip->hi_path = strdup(path);
105			if (!hip->hi_path) {
106			    free(hip);
107			    return;
108			}
109			hip->hi_basename = strrchr(hip->hi_path, '/');
110			if (hip->hi_basename) {
111				hip->hi_basename++;
112			} else {
113				hip->hi_basename = hip->hi_path;
114			}
115			STAILQ_INSERT_TAIL(&hi_list, hip, entries);
116		}
117	}
118}
119
120/**
121 * @brief get pcr result
122 */
123ssize_t
124ve_pcr_get(unsigned char *buf, size_t sz)
125{
126	if (!pcr_md)
127		return (-1);
128	if (sz < pcr_hlen)
129		return (-1);
130	pcr_md->out(&pcr_ctx.vtable, buf);
131	return (pcr_hlen);
132}
133
134/**
135 * @brief get list of paths in prc
136 */
137char *
138ve_pcr_hashed_get(int flags)
139{
140	const char *cp;
141	char *hinfo;
142	struct hashed_info *hip;
143	size_t nbytes;
144	size_t x;
145	int n;
146
147	n = 0;
148	nbytes = x = 0;
149	hinfo = NULL;
150	STAILQ_FOREACH(hip, &hi_list, entries) {
151		nbytes += 1 + strlen(flags ? hip->hi_basename : hip->hi_path);
152	}
153	if (nbytes > 1) {
154		hinfo = malloc(nbytes + 2);
155		if (hinfo) {
156			STAILQ_FOREACH(hip, &hi_list, entries) {
157				cp = flags ? hip->hi_basename : hip->hi_path;
158				n = snprintf(&hinfo[x], nbytes - x, "%s,", cp);
159				x += n;
160			}
161			if (x > 0) {
162				hinfo[x-1] = '\0';
163			}
164		}
165	}
166	return hinfo;
167}
168