1 /* 2 * Copyright (c) 2008 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthias Schmidt <matthias@dragonflybsd.org>, University of Marburg, 6 * Germany. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in 16 * the documentation and/or other materials provided with the 17 * distribution. 18 * 3. Neither the name of The DragonFly Project nor the names of its 19 * contributors may be used to endorse or promote products derived 20 * from this software without specific, prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 23 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 24 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 25 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 26 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 27 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 28 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 29 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 30 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 31 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 32 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include <openssl/x509.h> 37 #include <openssl/md5.h> 38 #include <openssl/ssl.h> 39 #include <openssl/err.h> 40 #include <openssl/pem.h> 41 #include <openssl/rand.h> 42 43 #include <strings.h> 44 #include <string.h> 45 #include <syslog.h> 46 47 #include "dma.h" 48 49 static int 50 init_cert_file(SSL_CTX *ctx, const char *path) 51 { 52 int error; 53 54 /* Load certificate into ctx */ 55 error = SSL_CTX_use_certificate_chain_file(ctx, path); 56 if (error < 1) { 57 syslog(LOG_ERR, "SSL: Cannot load certificate `%s': %s", path, ssl_errstr()); 58 return (-1); 59 } 60 61 /* Add private key to ctx */ 62 error = SSL_CTX_use_PrivateKey_file(ctx, path, SSL_FILETYPE_PEM); 63 if (error < 1) { 64 syslog(LOG_ERR, "SSL: Cannot load private key `%s': %s", path, ssl_errstr()); 65 return (-1); 66 } 67 68 /* 69 * Check the consistency of a private key with the corresponding 70 * certificate 71 */ 72 error = SSL_CTX_check_private_key(ctx); 73 if (error < 1) { 74 syslog(LOG_ERR, "SSL: Cannot check private key: %s", ssl_errstr()); 75 return (-1); 76 } 77 78 return (0); 79 } 80 81 static int 82 verify_server_fingerprint(const X509 *cert) 83 { 84 unsigned char fingerprint[EVP_MAX_MD_SIZE] = {0}; 85 unsigned int fingerprint_len = 0; 86 if(!X509_digest(cert, EVP_sha256(), fingerprint, &fingerprint_len)) { 87 syslog(LOG_WARNING, "failed to load fingerprint of server certicate: %s", 88 ssl_errstr()); 89 return (1); 90 } 91 if(fingerprint_len != SHA256_DIGEST_LENGTH) { 92 syslog(LOG_WARNING, "sha256 fingerprint has unexpected length of %d bytes", 93 fingerprint_len); 94 return (1); 95 } 96 if(memcmp(fingerprint, config.fingerprint, SHA256_DIGEST_LENGTH) != 0) { 97 syslog(LOG_WARNING, "fingerprints do not match"); 98 return (1); 99 } 100 syslog(LOG_DEBUG, "successfully verified server certificate fingerprint"); 101 return (0); 102 } 103 104 int 105 smtp_init_crypto(int fd, int feature, struct smtp_features* features) 106 { 107 SSL_CTX *ctx = NULL; 108 #if (OPENSSL_VERSION_NUMBER >= 0x00909000L) 109 const SSL_METHOD *meth = NULL; 110 #else 111 SSL_METHOD *meth = NULL; 112 #endif 113 X509 *cert; 114 int error; 115 116 /* XXX clean up on error/close */ 117 /* Init SSL library */ 118 SSL_library_init(); 119 SSL_load_error_strings(); 120 121 // Allow any possible version 122 #if (OPENSSL_VERSION_NUMBER >= 0x10100000L) 123 meth = TLS_client_method(); 124 #else 125 meth = SSLv23_client_method(); 126 #endif 127 128 ctx = SSL_CTX_new(meth); 129 if (ctx == NULL) { 130 syslog(LOG_WARNING, "remote delivery deferred: SSL init failed: %s", ssl_errstr()); 131 return (1); 132 } 133 134 /* User supplied a certificate */ 135 if (config.certfile != NULL) { 136 error = init_cert_file(ctx, config.certfile); 137 if (error) { 138 syslog(LOG_WARNING, "remote delivery deferred"); 139 return (1); 140 } 141 } 142 143 /* 144 * If the user wants STARTTLS, we have to send EHLO here 145 */ 146 if (((feature & SECURETRANSFER) != 0) && 147 (feature & STARTTLS) != 0) { 148 /* TLS init phase, disable SSL_write */ 149 config.features |= NOSSL; 150 151 if (perform_server_greeting(fd, features) == 0) { 152 send_remote_command(fd, "STARTTLS"); 153 if (read_remote(fd, 0, NULL) != 2) { 154 if ((feature & TLS_OPP) == 0) { 155 syslog(LOG_ERR, "remote delivery deferred: STARTTLS not available: %s", neterr); 156 return (1); 157 } else { 158 syslog(LOG_INFO, "in opportunistic TLS mode, STARTTLS not available: %s", neterr); 159 return (0); 160 } 161 } 162 } else { 163 syslog(LOG_ERR, "remote delivery deferred: could not perform server greeting: %s", 164 neterr); 165 return (1); 166 } 167 168 /* End of TLS init phase, enable SSL_write/read */ 169 config.features &= ~NOSSL; 170 } 171 172 config.ssl = SSL_new(ctx); 173 if (config.ssl == NULL) { 174 syslog(LOG_NOTICE, "remote delivery deferred: SSL struct creation failed: %s", 175 ssl_errstr()); 176 return (1); 177 } 178 179 /* Set ssl to work in client mode */ 180 SSL_set_connect_state(config.ssl); 181 182 /* Set fd for SSL in/output */ 183 error = SSL_set_fd(config.ssl, fd); 184 if (error == 0) { 185 syslog(LOG_NOTICE, "remote delivery deferred: SSL set fd failed: %s", 186 ssl_errstr()); 187 return (1); 188 } 189 190 /* Open SSL connection */ 191 error = SSL_connect(config.ssl); 192 if (error != 1) { 193 syslog(LOG_ERR, "remote delivery deferred: SSL handshake failed fatally: %s", 194 ssl_errstr()); 195 return (1); 196 } 197 198 /* Get peer certificate */ 199 cert = SSL_get_peer_certificate(config.ssl); 200 if (cert == NULL) { 201 syslog(LOG_WARNING, "remote delivery deferred: Peer did not provide certificate: %s", 202 ssl_errstr()); 203 return (1); 204 } 205 if(config.fingerprint != NULL && verify_server_fingerprint(cert)) { 206 X509_free(cert); 207 return (1); 208 } 209 X509_free(cert); 210 211 return (0); 212 } 213 214 /* 215 * hmac_md5() taken out of RFC 2104. This RFC was written by H. Krawczyk, 216 * M. Bellare and R. Canetti. 217 * 218 * text pointer to data stream 219 * text_len length of data stream 220 * key pointer to authentication key 221 * key_len length of authentication key 222 * digest caller digest to be filled int 223 */ 224 void 225 hmac_md5(unsigned char *text, int text_len, unsigned char *key, int key_len, 226 unsigned char* digest) 227 { 228 MD5_CTX context; 229 unsigned char k_ipad[65]; /* inner padding - 230 * key XORd with ipad 231 */ 232 unsigned char k_opad[65]; /* outer padding - 233 * key XORd with opad 234 */ 235 unsigned char tk[16]; 236 int i; 237 /* if key is longer than 64 bytes reset it to key=MD5(key) */ 238 if (key_len > 64) { 239 240 MD5_CTX tctx; 241 242 MD5_Init(&tctx); 243 MD5_Update(&tctx, key, key_len); 244 MD5_Final(tk, &tctx); 245 246 key = tk; 247 key_len = 16; 248 } 249 250 /* 251 * the HMAC_MD5 transform looks like: 252 * 253 * MD5(K XOR opad, MD5(K XOR ipad, text)) 254 * 255 * where K is an n byte key 256 * ipad is the byte 0x36 repeated 64 times 257 * 258 * opad is the byte 0x5c repeated 64 times 259 * and text is the data being protected 260 */ 261 262 /* start out by storing key in pads */ 263 bzero( k_ipad, sizeof k_ipad); 264 bzero( k_opad, sizeof k_opad); 265 bcopy( key, k_ipad, key_len); 266 bcopy( key, k_opad, key_len); 267 268 /* XOR key with ipad and opad values */ 269 for (i=0; i<64; i++) { 270 k_ipad[i] ^= 0x36; 271 k_opad[i] ^= 0x5c; 272 } 273 /* 274 * perform inner MD5 275 */ 276 MD5_Init(&context); /* init context for 1st 277 * pass */ 278 MD5_Update(&context, k_ipad, 64); /* start with inner pad */ 279 MD5_Update(&context, text, text_len); /* then text of datagram */ 280 MD5_Final(digest, &context); /* finish up 1st pass */ 281 /* 282 * perform outer MD5 283 */ 284 MD5_Init(&context); /* init context for 2nd 285 * pass */ 286 MD5_Update(&context, k_opad, 64); /* start with outer pad */ 287 MD5_Update(&context, digest, 16); /* then results of 1st 288 * hash */ 289 MD5_Final(digest, &context); /* finish up 2nd pass */ 290 } 291 292 /* 293 * CRAM-MD5 authentication 294 */ 295 int 296 smtp_auth_md5(int fd, char *login, char *password) 297 { 298 unsigned char digest[BUF_SIZE]; 299 char buffer[BUF_SIZE], ascii_digest[33]; 300 char *temp; 301 int len, i; 302 static char hextab[] = "0123456789abcdef"; 303 304 temp = calloc(BUF_SIZE, 1); 305 memset(buffer, 0, sizeof(buffer)); 306 memset(digest, 0, sizeof(digest)); 307 memset(ascii_digest, 0, sizeof(ascii_digest)); 308 309 /* Send AUTH command according to RFC 2554 */ 310 send_remote_command(fd, "AUTH CRAM-MD5"); 311 if (read_remote(fd, sizeof(buffer), buffer) != 3) { 312 syslog(LOG_DEBUG, "smarthost authentication:" 313 " AUTH cram-md5 not available: %s", neterr); 314 /* if cram-md5 is not available */ 315 free(temp); 316 return (-1); 317 } 318 319 /* skip 3 char status + 1 char space */ 320 base64_decode(buffer + 4, temp); 321 hmac_md5((unsigned char *)temp, strlen(temp), 322 (unsigned char *)password, strlen(password), digest); 323 free(temp); 324 325 ascii_digest[32] = 0; 326 for (i = 0; i < 16; i++) { 327 ascii_digest[2*i] = hextab[digest[i] >> 4]; 328 ascii_digest[2*i+1] = hextab[digest[i] & 15]; 329 } 330 331 /* prepare answer */ 332 snprintf(buffer, BUF_SIZE, "%s %s", login, ascii_digest); 333 334 /* encode answer */ 335 len = base64_encode(buffer, strlen(buffer), &temp); 336 if (len < 0) { 337 syslog(LOG_ERR, "can not encode auth reply: %m"); 338 return (-1); 339 } 340 341 /* send answer */ 342 send_remote_command(fd, "%s", temp); 343 free(temp); 344 if (read_remote(fd, 0, NULL) != 2) { 345 syslog(LOG_WARNING, "remote delivery deferred:" 346 " AUTH cram-md5 failed: %s", neterr); 347 return (-2); 348 } 349 350 return (0); 351 } 352