1 /* 2 * libkmod - module signature display 3 * 4 * Copyright (C) 2013 Michal Marek, SUSE 5 * 6 * This library is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU Lesser General Public 8 * License as published by the Free Software Foundation; either 9 * version 2.1 of the License, or (at your option) any later version. 10 * 11 * This library is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 * Lesser General Public License for more details. 15 * 16 * You should have received a copy of the GNU Lesser General Public 17 * License along with this library; if not, see <http://www.gnu.org/licenses/>. 18 */ 19 20 #include <inttypes.h> 21 #include <stdio.h> 22 #include <stdlib.h> 23 #include <string.h> 24 25 #include <shared/missing.h> 26 #include <shared/util.h> 27 28 #include "libkmod-internal.h" 29 30 /* These types and tables were copied from the 3.7 kernel sources. 31 * As this is just description of the signature format, it should not be 32 * considered derived work (so libkmod can use the LGPL license). 33 */ 34 enum pkey_algo { 35 PKEY_ALGO_DSA, 36 PKEY_ALGO_RSA, 37 PKEY_ALGO__LAST 38 }; 39 40 static const char *const pkey_algo[PKEY_ALGO__LAST] = { 41 [PKEY_ALGO_DSA] = "DSA", 42 [PKEY_ALGO_RSA] = "RSA", 43 }; 44 45 enum pkey_hash_algo { 46 PKEY_HASH_MD4, 47 PKEY_HASH_MD5, 48 PKEY_HASH_SHA1, 49 PKEY_HASH_RIPE_MD_160, 50 PKEY_HASH_SHA256, 51 PKEY_HASH_SHA384, 52 PKEY_HASH_SHA512, 53 PKEY_HASH_SHA224, 54 PKEY_HASH__LAST 55 }; 56 57 const char *const pkey_hash_algo[PKEY_HASH__LAST] = { 58 [PKEY_HASH_MD4] = "md4", 59 [PKEY_HASH_MD5] = "md5", 60 [PKEY_HASH_SHA1] = "sha1", 61 [PKEY_HASH_RIPE_MD_160] = "rmd160", 62 [PKEY_HASH_SHA256] = "sha256", 63 [PKEY_HASH_SHA384] = "sha384", 64 [PKEY_HASH_SHA512] = "sha512", 65 [PKEY_HASH_SHA224] = "sha224", 66 }; 67 68 enum pkey_id_type { 69 PKEY_ID_PGP, /* OpenPGP generated key ID */ 70 PKEY_ID_X509, /* X.509 arbitrary subjectKeyIdentifier */ 71 PKEY_ID_PKCS7, /* Signature in PKCS#7 message */ 72 PKEY_ID_TYPE__LAST 73 }; 74 75 const char *const pkey_id_type[PKEY_ID_TYPE__LAST] = { 76 [PKEY_ID_PGP] = "PGP", 77 [PKEY_ID_X509] = "X509", 78 [PKEY_ID_PKCS7] = "PKCS#7", 79 }; 80 81 /* 82 * Module signature information block. 83 */ 84 struct module_signature { 85 uint8_t algo; /* Public-key crypto algorithm [enum pkey_algo] */ 86 uint8_t hash; /* Digest algorithm [enum pkey_hash_algo] */ 87 uint8_t id_type; /* Key identifier type [enum pkey_id_type] */ 88 uint8_t signer_len; /* Length of signer's name */ 89 uint8_t key_id_len; /* Length of key identifier */ 90 uint8_t __pad[3]; 91 uint32_t sig_len; /* Length of signature data (big endian) */ 92 }; 93 94 #define SIG_MAGIC "~Module signature appended~\n" 95 96 /* 97 * A signed module has the following layout: 98 * 99 * [ module ] 100 * [ signer's name ] 101 * [ key identifier ] 102 * [ signature data ] 103 * [ struct module_signature ] 104 * [ SIG_MAGIC ] 105 */ 106 107 bool kmod_module_signature_info(const struct kmod_file *file, struct kmod_signature_info *sig_info) 108 { 109 const char *mem; 110 off_t size; 111 const struct module_signature *modsig; 112 size_t sig_len; 113 114 115 size = kmod_file_get_size(file); 116 mem = kmod_file_get_contents(file); 117 if (size < (off_t)strlen(SIG_MAGIC)) 118 return false; 119 size -= strlen(SIG_MAGIC); 120 if (memcmp(SIG_MAGIC, mem + size, strlen(SIG_MAGIC)) != 0) 121 return false; 122 123 if (size < (off_t)sizeof(struct module_signature)) 124 return false; 125 size -= sizeof(struct module_signature); 126 modsig = (struct module_signature *)(mem + size); 127 if (modsig->algo >= PKEY_ALGO__LAST || 128 modsig->hash >= PKEY_HASH__LAST || 129 modsig->id_type >= PKEY_ID_TYPE__LAST) 130 return false; 131 sig_len = be32toh(get_unaligned(&modsig->sig_len)); 132 if (sig_len == 0 || 133 size < (int64_t)(modsig->signer_len + modsig->key_id_len + sig_len)) 134 return false; 135 136 size -= modsig->key_id_len + sig_len; 137 sig_info->key_id = mem + size; 138 sig_info->key_id_len = modsig->key_id_len; 139 140 size -= modsig->signer_len; 141 sig_info->signer = mem + size; 142 sig_info->signer_len = modsig->signer_len; 143 144 sig_info->algo = pkey_algo[modsig->algo]; 145 sig_info->hash_algo = pkey_hash_algo[modsig->hash]; 146 sig_info->id_type = pkey_id_type[modsig->id_type]; 147 148 return true; 149 } 150
