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 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 78 ve_pcr_updating_get(void) 79 { 80 return (pcr_updating); 81 } 82 83 /** 84 * @brief set pcr_updating state 85 */ 86 void 87 ve_pcr_updating_set(int updating) 88 { 89 pcr_updating = updating; 90 } 91 92 /** 93 * @brief update pcr context 94 */ 95 void 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 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 * 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