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 OPENSSL_init_ssl(0, NULL); 119 120 // Allow any possible version 121 #if (OPENSSL_VERSION_NUMBER >= 0x10100000L) 122 meth = TLS_client_method(); 123 #else 124 meth = SSLv23_client_method(); 125 #endif 126 127 ctx = SSL_CTX_new(meth); 128 if (ctx == NULL) { 129 syslog(LOG_WARNING, "remote delivery deferred: SSL init failed: %s", ssl_errstr()); 130 return (1); 131 } 132 133 /* User supplied a certificate */ 134 if (config.certfile != NULL) { 135 error = init_cert_file(ctx, config.certfile); 136 if (error) { 137 syslog(LOG_WARNING, "remote delivery deferred"); 138 return (1); 139 } 140 } 141 142 /* 143 * If the user wants STARTTLS, we have to send EHLO here 144 */ 145 if (((feature & SECURETRANSFER) != 0) && 146 (feature & STARTTLS) != 0) { 147 /* TLS init phase, disable SSL_write */ 148 config.features |= NOSSL; 149 150 if (perform_server_greeting(fd, features) == 0) { 151 send_remote_command(fd, "STARTTLS"); 152 if (read_remote(fd, 0, NULL) != 2) { 153 if ((feature & TLS_OPP) == 0) { 154 syslog(LOG_ERR, "remote delivery deferred: STARTTLS not available: %s", neterr); 155 return (1); 156 } else { 157 syslog(LOG_INFO, "in opportunistic TLS mode, STARTTLS not available: %s", neterr); 158 return (0); 159 } 160 } 161 } else { 162 syslog(LOG_ERR, "remote delivery deferred: could not perform server greeting: %s", 163 neterr); 164 return (1); 165 } 166 167 /* End of TLS init phase, enable SSL_write/read */ 168 config.features &= ~NOSSL; 169 } 170 171 config.ssl = SSL_new(ctx); 172 if (config.ssl == NULL) { 173 syslog(LOG_NOTICE, "remote delivery deferred: SSL struct creation failed: %s", 174 ssl_errstr()); 175 return (1); 176 } 177 178 /* Set ssl to work in client mode */ 179 SSL_set_connect_state(config.ssl); 180 181 /* Set fd for SSL in/output */ 182 error = SSL_set_fd(config.ssl, fd); 183 if (error == 0) { 184 syslog(LOG_NOTICE, "remote delivery deferred: SSL set fd failed: %s", 185 ssl_errstr()); 186 return (1); 187 } 188 189 /* Open SSL connection */ 190 error = SSL_connect(config.ssl); 191 if (error != 1) { 192 syslog(LOG_ERR, "remote delivery deferred: SSL handshake failed fatally: %s", 193 ssl_errstr()); 194 return (1); 195 } 196 197 /* Get peer certificate */ 198 cert = SSL_get_peer_certificate(config.ssl); 199 if (cert == NULL) { 200 syslog(LOG_WARNING, "remote delivery deferred: Peer did not provide certificate: %s", 201 ssl_errstr()); 202 return (1); 203 } 204 if(config.fingerprint != NULL && verify_server_fingerprint(cert)) { 205 X509_free(cert); 206 return (1); 207 } 208 X509_free(cert); 209 210 return (0); 211 } 212 213 /* 214 * hmac_md5() taken out of RFC 2104. This RFC was written by H. Krawczyk, 215 * M. Bellare and R. Canetti. 216 * 217 * text pointer to data stream 218 * text_len length of data stream 219 * key pointer to authentication key 220 * key_len length of authentication key 221 * digest caller digest to be filled int 222 */ 223 void 224 hmac_md5(unsigned char *text, int text_len, unsigned char *key, int key_len, 225 unsigned char* digest) 226 { 227 MD5_CTX context; 228 unsigned char k_ipad[65]; /* inner padding - 229 * key XORd with ipad 230 */ 231 unsigned char k_opad[65]; /* outer padding - 232 * key XORd with opad 233 */ 234 unsigned char tk[16]; 235 int i; 236 /* if key is longer than 64 bytes reset it to key=MD5(key) */ 237 if (key_len > 64) { 238 239 MD5_CTX tctx; 240 241 MD5_Init(&tctx); 242 MD5_Update(&tctx, key, key_len); 243 MD5_Final(tk, &tctx); 244 245 key = tk; 246 key_len = 16; 247 } 248 249 /* 250 * the HMAC_MD5 transform looks like: 251 * 252 * MD5(K XOR opad, MD5(K XOR ipad, text)) 253 * 254 * where K is an n byte key 255 * ipad is the byte 0x36 repeated 64 times 256 * 257 * opad is the byte 0x5c repeated 64 times 258 * and text is the data being protected 259 */ 260 261 /* start out by storing key in pads */ 262 bzero( k_ipad, sizeof k_ipad); 263 bzero( k_opad, sizeof k_opad); 264 bcopy( key, k_ipad, key_len); 265 bcopy( key, k_opad, key_len); 266 267 /* XOR key with ipad and opad values */ 268 for (i=0; i<64; i++) { 269 k_ipad[i] ^= 0x36; 270 k_opad[i] ^= 0x5c; 271 } 272 /* 273 * perform inner MD5 274 */ 275 MD5_Init(&context); /* init context for 1st 276 * pass */ 277 MD5_Update(&context, k_ipad, 64); /* start with inner pad */ 278 MD5_Update(&context, text, text_len); /* then text of datagram */ 279 MD5_Final(digest, &context); /* finish up 1st pass */ 280 /* 281 * perform outer MD5 282 */ 283 MD5_Init(&context); /* init context for 2nd 284 * pass */ 285 MD5_Update(&context, k_opad, 64); /* start with outer pad */ 286 MD5_Update(&context, digest, 16); /* then results of 1st 287 * hash */ 288 MD5_Final(digest, &context); /* finish up 2nd pass */ 289 } 290 291 /* 292 * CRAM-MD5 authentication 293 */ 294 int 295 smtp_auth_md5(int fd, char *login, char *password) 296 { 297 unsigned char digest[BUF_SIZE]; 298 char buffer[BUF_SIZE], ascii_digest[33]; 299 char *temp; 300 int len, i; 301 static char hextab[] = "0123456789abcdef"; 302 303 temp = calloc(BUF_SIZE, 1); 304 memset(buffer, 0, sizeof(buffer)); 305 memset(digest, 0, sizeof(digest)); 306 memset(ascii_digest, 0, sizeof(ascii_digest)); 307 308 /* Send AUTH command according to RFC 2554 */ 309 send_remote_command(fd, "AUTH CRAM-MD5"); 310 if (read_remote(fd, sizeof(buffer), buffer) != 3) { 311 syslog(LOG_DEBUG, "smarthost authentication:" 312 " AUTH cram-md5 not available: %s", neterr); 313 /* if cram-md5 is not available */ 314 free(temp); 315 return (-1); 316 } 317 318 /* skip 3 char status + 1 char space */ 319 base64_decode(buffer + 4, temp); 320 hmac_md5((unsigned char *)temp, strlen(temp), 321 (unsigned char *)password, strlen(password), digest); 322 free(temp); 323 324 ascii_digest[32] = 0; 325 for (i = 0; i < 16; i++) { 326 ascii_digest[2*i] = hextab[digest[i] >> 4]; 327 ascii_digest[2*i+1] = hextab[digest[i] & 15]; 328 } 329 330 /* prepare answer */ 331 snprintf(buffer, BUF_SIZE, "%s %s", login, ascii_digest); 332 333 /* encode answer */ 334 len = base64_encode(buffer, strlen(buffer), &temp); 335 if (len < 0) { 336 syslog(LOG_ERR, "can not encode auth reply: %m"); 337 return (-1); 338 } 339 340 /* send answer */ 341 send_remote_command(fd, "%s", temp); 342 free(temp); 343 if (read_remote(fd, 0, NULL) != 2) { 344 syslog(LOG_WARNING, "remote delivery deferred:" 345 " AUTH cram-md5 failed: %s", neterr); 346 return (-2); 347 } 348 349 return (0); 350 } 351