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 __FBSDID("$FreeBSD$");
27
28 #include <sys/queue.h>
29 #include "libsecureboot-priv.h"
30
31 /*
32 * To support measured boot without putting a ton
33 * of extra code in the loader, we just maintain
34 * a hash of all the hashes we (attempt to) verify.
35 * The loader can export this for kernel or rc script
36 * to feed to a TPM pcr register - hence the name ve_pcr.
37 *
38 * NOTE: in the current standard the TPM pcr register size is for SHA1,
39 * the fact that we provide a SHA256 hash should not matter
40 * as long as we are consistent - it can be truncated or hashed
41 * before feeding to TPM.
42 */
43
44 static const br_hash_class *pcr_md = NULL;
45 static br_hash_compat_context pcr_ctx;
46 static size_t pcr_hlen = 0;
47 static int pcr_updating = -1;
48
49 struct hashed_info {
50 const char *hi_path;
51 const char *hi_basename;
52 STAILQ_ENTRY(hashed_info) entries;
53 };
54
55 static STAILQ_HEAD(, hashed_info) hi_list;
56
57
58 /**
59 * @brief initialize pcr context
60 *
61 * Real TPM registers only hold a SHA1 hash
62 * but we use SHA256
63 */
64 void
ve_pcr_init(void)65 ve_pcr_init(void)
66 {
67 if (pcr_updating < 0) {
68 pcr_updating = 0;
69 pcr_hlen = br_sha256_SIZE;
70 pcr_md = &br_sha256_vtable;
71 pcr_md->init(&pcr_ctx.vtable);
72 STAILQ_INIT(&hi_list);
73 }
74 }
75
76 /**
77 * @brief get pcr_updating state
78 */
79 int
ve_pcr_updating_get(void)80 ve_pcr_updating_get(void)
81 {
82 return (pcr_updating);
83 }
84
85 /**
86 * @brief set pcr_updating state
87 */
88 void
ve_pcr_updating_set(int updating)89 ve_pcr_updating_set(int updating)
90 {
91 pcr_updating = updating;
92 }
93
94 /**
95 * @brief update pcr context
96 */
97 void
ve_pcr_update(const char * path,unsigned char * data,size_t dlen)98 ve_pcr_update(const char *path, unsigned char *data, size_t dlen)
99 {
100 struct hashed_info *hip;
101
102 if (pcr_updating > 0 && pcr_md != NULL) {
103 pcr_md->update(&pcr_ctx.vtable, data, dlen);
104 /* if mallocs fail, measured boot will likely fail too */
105 if ((hip = malloc(sizeof(struct hashed_info)))) {
106 hip->hi_path = strdup(path);
107 if (!hip->hi_path) {
108 free(hip);
109 return;
110 }
111 hip->hi_basename = strrchr(hip->hi_path, '/');
112 if (hip->hi_basename) {
113 hip->hi_basename++;
114 } else {
115 hip->hi_basename = hip->hi_path;
116 }
117 STAILQ_INSERT_TAIL(&hi_list, hip, entries);
118 }
119 }
120 }
121
122 /**
123 * @brief get pcr result
124 */
125 ssize_t
ve_pcr_get(unsigned char * buf,size_t sz)126 ve_pcr_get(unsigned char *buf, size_t sz)
127 {
128 if (!pcr_md)
129 return (-1);
130 if (sz < pcr_hlen)
131 return (-1);
132 pcr_md->out(&pcr_ctx.vtable, buf);
133 return (pcr_hlen);
134 }
135
136 /**
137 * @brief get list of paths in prc
138 */
139 char *
ve_pcr_hashed_get(int flags)140 ve_pcr_hashed_get(int flags)
141 {
142 const char *cp;
143 char *hinfo;
144 struct hashed_info *hip;
145 size_t nbytes;
146 size_t x;
147 int n;
148
149 n = 0;
150 nbytes = x = 0;
151 hinfo = NULL;
152 STAILQ_FOREACH(hip, &hi_list, entries) {
153 nbytes += 1 + strlen(flags ? hip->hi_basename : hip->hi_path);
154 }
155 if (nbytes > 1) {
156 hinfo = malloc(nbytes + 2);
157 if (hinfo) {
158 STAILQ_FOREACH(hip, &hi_list, entries) {
159 cp = flags ? hip->hi_basename : hip->hi_path;
160 n = snprintf(&hinfo[x], nbytes - x, "%s,", cp);
161 x += n;
162 }
163 if (x > 0) {
164 hinfo[x-1] = '\0';
165 }
166 }
167 }
168 return hinfo;
169 }
170