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
42 static const br_hash_class *pcr_md = NULL;
43 static br_hash_compat_context pcr_ctx;
44 static size_t pcr_hlen = 0;
45 static int pcr_updating = -1;
46
47 struct hashed_info {
48 const char *hi_path;
49 const char *hi_basename;
50 STAILQ_ENTRY(hashed_info) entries;
51 };
52
53 static 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 */
62 void
ve_pcr_init(void)63 ve_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 */
77 int
ve_pcr_updating_get(void)78 ve_pcr_updating_get(void)
79 {
80 return (pcr_updating);
81 }
82
83 /**
84 * @brief set pcr_updating state
85 */
86 void
ve_pcr_updating_set(int updating)87 ve_pcr_updating_set(int updating)
88 {
89 pcr_updating = updating;
90 }
91
92 /**
93 * @brief update pcr context
94 */
95 void
ve_pcr_update(const char * path,unsigned char * data,size_t dlen)96 ve_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 */
123 ssize_t
ve_pcr_get(unsigned char * buf,size_t sz)124 ve_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 */
137 char *
ve_pcr_hashed_get(int flags)138 ve_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