xref: /freebsd/lib/libsecureboot/vepcr.c (revision 53f151f90603580d0c0a8fa1840ba1262958a7c1) 
15fff9558SSimon J. Gerraty /*-
25fff9558SSimon J. Gerraty  * Copyright (c) 2018, Juniper Networks, Inc.
35fff9558SSimon J. Gerraty  *
45fff9558SSimon J. Gerraty  * Redistribution and use in source and binary forms, with or without
55fff9558SSimon J. Gerraty  * modification, are permitted provided that the following conditions
65fff9558SSimon J. Gerraty  * are met:
75fff9558SSimon J. Gerraty  * 1. Redistributions of source code must retain the above copyright
85fff9558SSimon J. Gerraty  *    notice, this list of conditions and the following disclaimer.
95fff9558SSimon J. Gerraty  * 2. Redistributions in binary form must reproduce the above copyright
105fff9558SSimon J. Gerraty  *    notice, this list of conditions and the following disclaimer in the
115fff9558SSimon J. Gerraty  *    documentation and/or other materials provided with the distribution.
125fff9558SSimon J. Gerraty  *
135fff9558SSimon J. Gerraty  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
145fff9558SSimon J. Gerraty  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
155fff9558SSimon J. Gerraty  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
165fff9558SSimon J. Gerraty  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
175fff9558SSimon J. Gerraty  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
185fff9558SSimon J. Gerraty  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
195fff9558SSimon J. Gerraty  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
205fff9558SSimon J. Gerraty  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
215fff9558SSimon J. Gerraty  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
225fff9558SSimon J. Gerraty  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
235fff9558SSimon J. Gerraty  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
245fff9558SSimon J. Gerraty  */
255fff9558SSimon J. Gerraty #include <sys/cdefs.h>
265fff9558SSimon J. Gerraty __FBSDID("$FreeBSD$");
275fff9558SSimon J. Gerraty 
28*53f151f9SSimon J. Gerraty #include <sys/queue.h>
295fff9558SSimon J. Gerraty #include "libsecureboot-priv.h"
305fff9558SSimon J. Gerraty 
315fff9558SSimon J. Gerraty /*
325fff9558SSimon J. Gerraty  * To support measured boot without putting a ton
335fff9558SSimon J. Gerraty  * of extra code in the loader, we just maintain
345fff9558SSimon J. Gerraty  * a hash of all the hashes we (attempt to) verify.
355fff9558SSimon J. Gerraty  * The loader can export this for kernel or rc script
365fff9558SSimon J. Gerraty  * to feed to a TPM pcr register - hence the name ve_pcr.
375fff9558SSimon J. Gerraty  *
385fff9558SSimon J. Gerraty  * NOTE: in the current standard the TPM pcr register size is for SHA1,
395fff9558SSimon J. Gerraty  * the fact that we provide a SHA256 hash should not matter
405fff9558SSimon J. Gerraty  * as long as we are consistent - it can be truncated or hashed
415fff9558SSimon J. Gerraty  * before feeding to TPM.
425fff9558SSimon J. Gerraty  */
435fff9558SSimon J. Gerraty 
445fff9558SSimon J. Gerraty static const br_hash_class *pcr_md = NULL;
455fff9558SSimon J. Gerraty static br_hash_compat_context pcr_ctx;
465fff9558SSimon J. Gerraty static size_t pcr_hlen = 0;
47*53f151f9SSimon J. Gerraty static int pcr_updating = -1;
48*53f151f9SSimon J. Gerraty 
49*53f151f9SSimon J. Gerraty struct hashed_info {
50*53f151f9SSimon J. Gerraty 	const char *hi_path;
51*53f151f9SSimon J. Gerraty 	const char *hi_basename;
52*53f151f9SSimon J. Gerraty 	STAILQ_ENTRY(hashed_info) entries;
53*53f151f9SSimon J. Gerraty };
54*53f151f9SSimon J. Gerraty 
55*53f151f9SSimon J. Gerraty static STAILQ_HEAD(, hashed_info) hi_list;
56*53f151f9SSimon J. Gerraty 
575fff9558SSimon J. Gerraty 
585fff9558SSimon J. Gerraty /**
595fff9558SSimon J. Gerraty  * @brief initialize pcr context
605fff9558SSimon J. Gerraty  *
615fff9558SSimon J. Gerraty  * Real TPM registers only hold a SHA1 hash
625fff9558SSimon J. Gerraty  * but we use SHA256
635fff9558SSimon J. Gerraty  */
645fff9558SSimon J. Gerraty void
655fff9558SSimon J. Gerraty ve_pcr_init(void)
665fff9558SSimon J. Gerraty {
67*53f151f9SSimon J. Gerraty 	if (pcr_updating < 0) {
68980bde58SSimon J. Gerraty 		pcr_updating = 0;
695fff9558SSimon J. Gerraty 		pcr_hlen = br_sha256_SIZE;
705fff9558SSimon J. Gerraty 		pcr_md = &br_sha256_vtable;
715fff9558SSimon J. Gerraty 		pcr_md->init(&pcr_ctx.vtable);
72*53f151f9SSimon J. Gerraty 		STAILQ_INIT(&hi_list);
73*53f151f9SSimon J. Gerraty 	}
745fff9558SSimon J. Gerraty }
755fff9558SSimon J. Gerraty 
765fff9558SSimon J. Gerraty /**
77980bde58SSimon J. Gerraty  * @brief get pcr_updating state
78980bde58SSimon J. Gerraty  */
79980bde58SSimon J. Gerraty int
80980bde58SSimon J. Gerraty ve_pcr_updating_get(void)
81980bde58SSimon J. Gerraty {
82980bde58SSimon J. Gerraty 	return (pcr_updating);
83980bde58SSimon J. Gerraty }
84980bde58SSimon J. Gerraty 
85980bde58SSimon J. Gerraty /**
86980bde58SSimon J. Gerraty  * @brief set pcr_updating state
87980bde58SSimon J. Gerraty  */
88980bde58SSimon J. Gerraty void
89980bde58SSimon J. Gerraty ve_pcr_updating_set(int updating)
90980bde58SSimon J. Gerraty {
91980bde58SSimon J. Gerraty 	pcr_updating = updating;
92980bde58SSimon J. Gerraty }
93980bde58SSimon J. Gerraty 
94980bde58SSimon J. Gerraty /**
955fff9558SSimon J. Gerraty  * @brief update pcr context
965fff9558SSimon J. Gerraty  */
975fff9558SSimon J. Gerraty void
98*53f151f9SSimon J. Gerraty ve_pcr_update(const char *path, unsigned char *data, size_t dlen)
995fff9558SSimon J. Gerraty {
100*53f151f9SSimon J. Gerraty 	struct hashed_info *hip;
101*53f151f9SSimon J. Gerraty 
102*53f151f9SSimon J. Gerraty 	if (pcr_updating > 0 && pcr_md != NULL) {
1035fff9558SSimon J. Gerraty 		pcr_md->update(&pcr_ctx.vtable, data, dlen);
104*53f151f9SSimon J. Gerraty 		/* if mallocs fail, measured boot will likely fail too */
105*53f151f9SSimon J. Gerraty 		if ((hip = malloc(sizeof(struct hashed_info)))) {
106*53f151f9SSimon J. Gerraty 			hip->hi_path = strdup(path);
107*53f151f9SSimon J. Gerraty 			if (!hip->hi_path) {
108*53f151f9SSimon J. Gerraty 			    free(hip);
109*53f151f9SSimon J. Gerraty 			    return;
110*53f151f9SSimon J. Gerraty 			}
111*53f151f9SSimon J. Gerraty 			hip->hi_basename = strrchr(hip->hi_path, '/');
112*53f151f9SSimon J. Gerraty 			if (hip->hi_basename) {
113*53f151f9SSimon J. Gerraty 				hip->hi_basename++;
114*53f151f9SSimon J. Gerraty 			} else {
115*53f151f9SSimon J. Gerraty 				hip->hi_basename = hip->hi_path;
116*53f151f9SSimon J. Gerraty 			}
117*53f151f9SSimon J. Gerraty 			STAILQ_INSERT_TAIL(&hi_list, hip, entries);
118*53f151f9SSimon J. Gerraty 		}
119*53f151f9SSimon J. Gerraty 	}
1205fff9558SSimon J. Gerraty }
1215fff9558SSimon J. Gerraty 
1225fff9558SSimon J. Gerraty /**
1235fff9558SSimon J. Gerraty  * @brief get pcr result
1245fff9558SSimon J. Gerraty  */
1255fff9558SSimon J. Gerraty ssize_t
1265fff9558SSimon J. Gerraty ve_pcr_get(unsigned char *buf, size_t sz)
1275fff9558SSimon J. Gerraty {
1285fff9558SSimon J. Gerraty 	if (!pcr_md)
1295fff9558SSimon J. Gerraty 		return (-1);
1305fff9558SSimon J. Gerraty 	if (sz < pcr_hlen)
1315fff9558SSimon J. Gerraty 		return (-1);
1325fff9558SSimon J. Gerraty 	pcr_md->out(&pcr_ctx.vtable, buf);
1335fff9558SSimon J. Gerraty 	return (pcr_hlen);
1345fff9558SSimon J. Gerraty }
1355fff9558SSimon J. Gerraty 
136*53f151f9SSimon J. Gerraty /**
137*53f151f9SSimon J. Gerraty  * @brief get list of paths in prc
138*53f151f9SSimon J. Gerraty  */
139*53f151f9SSimon J. Gerraty char *
140*53f151f9SSimon J. Gerraty ve_pcr_hashed_get(int flags)
141*53f151f9SSimon J. Gerraty {
142*53f151f9SSimon J. Gerraty 	const char *cp;
143*53f151f9SSimon J. Gerraty 	char *hinfo;
144*53f151f9SSimon J. Gerraty 	struct hashed_info *hip;
145*53f151f9SSimon J. Gerraty 	size_t nbytes;
146*53f151f9SSimon J. Gerraty 	size_t x;
147*53f151f9SSimon J. Gerraty 	int n;
148*53f151f9SSimon J. Gerraty 
149*53f151f9SSimon J. Gerraty 	n = 0;
150*53f151f9SSimon J. Gerraty 	nbytes = x = 0;
151*53f151f9SSimon J. Gerraty 	hinfo = NULL;
152*53f151f9SSimon J. Gerraty 	STAILQ_FOREACH(hip, &hi_list, entries) {
153*53f151f9SSimon J. Gerraty 		nbytes += 1 + strlen(flags ? hip->hi_basename : hip->hi_path);
154*53f151f9SSimon J. Gerraty 	}
155*53f151f9SSimon J. Gerraty 	if (nbytes > 1) {
156*53f151f9SSimon J. Gerraty 		hinfo = malloc(nbytes + 2);
157*53f151f9SSimon J. Gerraty 		if (hinfo) {
158*53f151f9SSimon J. Gerraty 			STAILQ_FOREACH(hip, &hi_list, entries) {
159*53f151f9SSimon J. Gerraty 				cp = flags ? hip->hi_basename : hip->hi_path;
160*53f151f9SSimon J. Gerraty 				n = snprintf(&hinfo[x], nbytes - x, "%s,", cp);
161*53f151f9SSimon J. Gerraty 				x += n;
162*53f151f9SSimon J. Gerraty 			}
163*53f151f9SSimon J. Gerraty 			if (x > 0) {
164*53f151f9SSimon J. Gerraty 				hinfo[x-1] = '\0';
165*53f151f9SSimon J. Gerraty 			}
166*53f151f9SSimon J. Gerraty 		}
167*53f151f9SSimon J. Gerraty 	}
168*53f151f9SSimon J. Gerraty 	return hinfo;
169*53f151f9SSimon J. Gerraty }
170