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 "libsecureboot-priv.h" 29 30 /* 31 * To support measured boot without putting a ton 32 * of extra code in the loader, we just maintain 33 * a hash of all the hashes we (attempt to) verify. 34 * The loader can export this for kernel or rc script 35 * to feed to a TPM pcr register - hence the name ve_pcr. 36 * 37 * NOTE: in the current standard the TPM pcr register size is for SHA1, 38 * the fact that we provide a SHA256 hash should not matter 39 * as long as we are consistent - it can be truncated or hashed 40 * before feeding to TPM. 41 */ 42 43 static const br_hash_class *pcr_md = NULL; 44 static br_hash_compat_context pcr_ctx; 45 static size_t pcr_hlen = 0; 46 static int pcr_updating; 47 48 /** 49 * @brief initialize pcr context 50 * 51 * Real TPM registers only hold a SHA1 hash 52 * but we use SHA256 53 */ 54 void 55 ve_pcr_init(void) 56 { 57 pcr_updating = 0; 58 pcr_hlen = br_sha256_SIZE; 59 pcr_md = &br_sha256_vtable; 60 pcr_md->init(&pcr_ctx.vtable); 61 } 62 63 /** 64 * @brief get pcr_updating state 65 */ 66 int 67 ve_pcr_updating_get(void) 68 { 69 return (pcr_updating); 70 } 71 72 /** 73 * @brief set pcr_updating state 74 */ 75 void 76 ve_pcr_updating_set(int updating) 77 { 78 pcr_updating = updating; 79 } 80 81 /** 82 * @brief update pcr context 83 */ 84 void 85 ve_pcr_update(unsigned char *data, size_t dlen) 86 { 87 if (pcr_updating != 0 && pcr_md != NULL) 88 pcr_md->update(&pcr_ctx.vtable, data, dlen); 89 } 90 91 /** 92 * @brief get pcr result 93 */ 94 ssize_t 95 ve_pcr_get(unsigned char *buf, size_t sz) 96 { 97 if (!pcr_md) 98 return (-1); 99 if (sz < pcr_hlen) 100 return (-1); 101 pcr_md->out(&pcr_ctx.vtable, buf); 102 return (pcr_hlen); 103 } 104 105