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 <syslog.h> 44 45 #include "dma.h" 46 47 static int 48 init_cert_file(SSL_CTX *ctx, const char *path) 49 { 50 int error; 51 52 /* Load certificate into ctx */ 53 error = SSL_CTX_use_certificate_chain_file(ctx, path); 54 if (error < 1) { 55 syslog(LOG_ERR, "SSL: Cannot load certificate `%s': %s", path, ssl_errstr()); 56 return (-1); 57 } 58 59 /* Add private key to ctx */ 60 error = SSL_CTX_use_PrivateKey_file(ctx, path, SSL_FILETYPE_PEM); 61 if (error < 1) { 62 syslog(LOG_ERR, "SSL: Cannot load private key `%s': %s", path, ssl_errstr()); 63 return (-1); 64 } 65 66 /* 67 * Check the consistency of a private key with the corresponding 68 * certificate 69 */ 70 error = SSL_CTX_check_private_key(ctx); 71 if (error < 1) { 72 syslog(LOG_ERR, "SSL: Cannot check private key: %s", ssl_errstr()); 73 return (-1); 74 } 75 76 return (0); 77 } 78 79 int 80 smtp_init_crypto(int fd, int feature) 81 { 82 SSL_CTX *ctx = NULL; 83 #if (OPENSSL_VERSION_NUMBER >= 0x00909000L) 84 const SSL_METHOD *meth = NULL; 85 #else 86 SSL_METHOD *meth = NULL; 87 #endif 88 X509 *cert; 89 int error; 90 91 /* XXX clean up on error/close */ 92 /* Init SSL library */ 93 SSL_library_init(); 94 SSL_load_error_strings(); 95 96 // Allow any possible version 97 #if (OPENSSL_VERSION_NUMBER >= 0x10100000L) 98 meth = TLS_client_method(); 99 #else 100 meth = SSLv23_client_method(); 101 #endif 102 103 ctx = SSL_CTX_new(meth); 104 if (ctx == NULL) { 105 syslog(LOG_WARNING, "remote delivery deferred: SSL init failed: %s", ssl_errstr()); 106 return (1); 107 } 108 109 /* User supplied a certificate */ 110 if (config.certfile != NULL) { 111 error = init_cert_file(ctx, config.certfile); 112 if (error) { 113 syslog(LOG_WARNING, "remote delivery deferred"); 114 return (1); 115 } 116 } 117 118 /* 119 * If the user wants STARTTLS, we have to send EHLO here 120 */ 121 if (((feature & SECURETRANS) != 0) && 122 (feature & STARTTLS) != 0) { 123 /* TLS init phase, disable SSL_write */ 124 config.features |= NOSSL; 125 126 send_remote_command(fd, "EHLO %s", hostname()); 127 if (read_remote(fd, 0, NULL) == 2) { 128 send_remote_command(fd, "STARTTLS"); 129 if (read_remote(fd, 0, NULL) != 2) { 130 if ((feature & TLS_OPP) == 0) { 131 syslog(LOG_ERR, "remote delivery deferred: STARTTLS not available: %s", neterr); 132 return (1); 133 } else { 134 syslog(LOG_INFO, "in opportunistic TLS mode, STARTTLS not available: %s", neterr); 135 return (0); 136 } 137 } 138 } 139 /* End of TLS init phase, enable SSL_write/read */ 140 config.features &= ~NOSSL; 141 } 142 143 config.ssl = SSL_new(ctx); 144 if (config.ssl == NULL) { 145 syslog(LOG_NOTICE, "remote delivery deferred: SSL struct creation failed: %s", 146 ssl_errstr()); 147 return (1); 148 } 149 150 /* Set ssl to work in client mode */ 151 SSL_set_connect_state(config.ssl); 152 153 /* Set fd for SSL in/output */ 154 error = SSL_set_fd(config.ssl, fd); 155 if (error == 0) { 156 syslog(LOG_NOTICE, "remote delivery deferred: SSL set fd failed: %s", 157 ssl_errstr()); 158 return (1); 159 } 160 161 /* Open SSL connection */ 162 error = SSL_connect(config.ssl); 163 if (error < 0) { 164 syslog(LOG_ERR, "remote delivery deferred: SSL handshake failed fatally: %s", 165 ssl_errstr()); 166 return (1); 167 } 168 169 /* Get peer certificate */ 170 cert = SSL_get_peer_certificate(config.ssl); 171 if (cert == NULL) { 172 syslog(LOG_WARNING, "remote delivery deferred: Peer did not provide certificate: %s", 173 ssl_errstr()); 174 } 175 X509_free(cert); 176 177 return (0); 178 } 179 180 /* 181 * hmac_md5() taken out of RFC 2104. This RFC was written by H. Krawczyk, 182 * M. Bellare and R. Canetti. 183 * 184 * text pointer to data stream 185 * text_len length of data stream 186 * key pointer to authentication key 187 * key_len length of authentication key 188 * digest caller digest to be filled int 189 */ 190 void 191 hmac_md5(unsigned char *text, int text_len, unsigned char *key, int key_len, 192 unsigned char* digest) 193 { 194 MD5_CTX context; 195 unsigned char k_ipad[65]; /* inner padding - 196 * key XORd with ipad 197 */ 198 unsigned char k_opad[65]; /* outer padding - 199 * key XORd with opad 200 */ 201 unsigned char tk[16]; 202 int i; 203 /* if key is longer than 64 bytes reset it to key=MD5(key) */ 204 if (key_len > 64) { 205 206 MD5_CTX tctx; 207 208 MD5_Init(&tctx); 209 MD5_Update(&tctx, key, key_len); 210 MD5_Final(tk, &tctx); 211 212 key = tk; 213 key_len = 16; 214 } 215 216 /* 217 * the HMAC_MD5 transform looks like: 218 * 219 * MD5(K XOR opad, MD5(K XOR ipad, text)) 220 * 221 * where K is an n byte key 222 * ipad is the byte 0x36 repeated 64 times 223 * 224 * opad is the byte 0x5c repeated 64 times 225 * and text is the data being protected 226 */ 227 228 /* start out by storing key in pads */ 229 bzero( k_ipad, sizeof k_ipad); 230 bzero( k_opad, sizeof k_opad); 231 bcopy( key, k_ipad, key_len); 232 bcopy( key, k_opad, key_len); 233 234 /* XOR key with ipad and opad values */ 235 for (i=0; i<64; i++) { 236 k_ipad[i] ^= 0x36; 237 k_opad[i] ^= 0x5c; 238 } 239 /* 240 * perform inner MD5 241 */ 242 MD5_Init(&context); /* init context for 1st 243 * pass */ 244 MD5_Update(&context, k_ipad, 64); /* start with inner pad */ 245 MD5_Update(&context, text, text_len); /* then text of datagram */ 246 MD5_Final(digest, &context); /* finish up 1st pass */ 247 /* 248 * perform outer MD5 249 */ 250 MD5_Init(&context); /* init context for 2nd 251 * pass */ 252 MD5_Update(&context, k_opad, 64); /* start with outer pad */ 253 MD5_Update(&context, digest, 16); /* then results of 1st 254 * hash */ 255 MD5_Final(digest, &context); /* finish up 2nd pass */ 256 } 257 258 /* 259 * CRAM-MD5 authentication 260 */ 261 int 262 smtp_auth_md5(int fd, char *login, char *password) 263 { 264 unsigned char digest[BUF_SIZE]; 265 char buffer[BUF_SIZE], ascii_digest[33]; 266 char *temp; 267 int len, i; 268 static char hextab[] = "0123456789abcdef"; 269 270 temp = calloc(BUF_SIZE, 1); 271 memset(buffer, 0, sizeof(buffer)); 272 memset(digest, 0, sizeof(digest)); 273 memset(ascii_digest, 0, sizeof(ascii_digest)); 274 275 /* Send AUTH command according to RFC 2554 */ 276 send_remote_command(fd, "AUTH CRAM-MD5"); 277 if (read_remote(fd, sizeof(buffer), buffer) != 3) { 278 syslog(LOG_DEBUG, "smarthost authentication:" 279 " AUTH cram-md5 not available: %s", neterr); 280 /* if cram-md5 is not available */ 281 free(temp); 282 return (-1); 283 } 284 285 /* skip 3 char status + 1 char space */ 286 base64_decode(buffer + 4, temp); 287 hmac_md5((unsigned char *)temp, strlen(temp), 288 (unsigned char *)password, strlen(password), digest); 289 free(temp); 290 291 ascii_digest[32] = 0; 292 for (i = 0; i < 16; i++) { 293 ascii_digest[2*i] = hextab[digest[i] >> 4]; 294 ascii_digest[2*i+1] = hextab[digest[i] & 15]; 295 } 296 297 /* prepare answer */ 298 snprintf(buffer, BUF_SIZE, "%s %s", login, ascii_digest); 299 300 /* encode answer */ 301 len = base64_encode(buffer, strlen(buffer), &temp); 302 if (len < 0) { 303 syslog(LOG_ERR, "can not encode auth reply: %m"); 304 return (-1); 305 } 306 307 /* send answer */ 308 send_remote_command(fd, "%s", temp); 309 free(temp); 310 if (read_remote(fd, 0, NULL) != 2) { 311 syslog(LOG_WARNING, "remote delivery deferred:" 312 " AUTH cram-md5 failed: %s", neterr); 313 return (-2); 314 } 315 316 return (0); 317 } 318