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 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 80 ve_pcr_updating_get(void) 81 { 82 return (pcr_updating); 83 } 84 85 /** 86 * @brief set pcr_updating state 87 */ 88 void 89 ve_pcr_updating_set(int updating) 90 { 91 pcr_updating = updating; 92 } 93 94 /** 95 * @brief update pcr context 96 */ 97 void 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 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 * 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