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 meth = TLSv1_client_method(); 97 98 ctx = SSL_CTX_new(meth); 99 if (ctx == NULL) { 100 syslog(LOG_WARNING, "remote delivery deferred: SSL init failed: %s", ssl_errstr()); 101 return (1); 102 } 103 104 /* User supplied a certificate */ 105 if (config.certfile != NULL) { 106 error = init_cert_file(ctx, config.certfile); 107 if (error) { 108 syslog(LOG_WARNING, "remote delivery deferred"); 109 return (1); 110 } 111 } 112 113 /* 114 * If the user wants STARTTLS, we have to send EHLO here 115 */ 116 if (((feature & SECURETRANS) != 0) && 117 (feature & STARTTLS) != 0) { 118 /* TLS init phase, disable SSL_write */ 119 config.features |= NOSSL; 120 121 send_remote_command(fd, "EHLO %s", hostname()); 122 if (read_remote(fd, 0, NULL) == 2) { 123 send_remote_command(fd, "STARTTLS"); 124 if (read_remote(fd, 0, NULL) != 2) { 125 if ((feature & TLS_OPP) == 0) { 126 syslog(LOG_ERR, "remote delivery deferred: STARTTLS not available: %s", neterr); 127 return (1); 128 } else { 129 syslog(LOG_INFO, "in opportunistic TLS mode, STARTTLS not available: %s", neterr); 130 return (0); 131 } 132 } 133 } 134 /* End of TLS init phase, enable SSL_write/read */ 135 config.features &= ~NOSSL; 136 } 137 138 config.ssl = SSL_new(ctx); 139 if (config.ssl == NULL) { 140 syslog(LOG_NOTICE, "remote delivery deferred: SSL struct creation failed: %s", 141 ssl_errstr()); 142 return (1); 143 } 144 145 /* Set ssl to work in client mode */ 146 SSL_set_connect_state(config.ssl); 147 148 /* Set fd for SSL in/output */ 149 error = SSL_set_fd(config.ssl, fd); 150 if (error == 0) { 151 syslog(LOG_NOTICE, "remote delivery deferred: SSL set fd failed: %s", 152 ssl_errstr()); 153 return (1); 154 } 155 156 /* Open SSL connection */ 157 error = SSL_connect(config.ssl); 158 if (error < 0) { 159 syslog(LOG_ERR, "remote delivery deferred: SSL handshake failed fatally: %s", 160 ssl_errstr()); 161 return (1); 162 } 163 164 /* Get peer certificate */ 165 cert = SSL_get_peer_certificate(config.ssl); 166 if (cert == NULL) { 167 syslog(LOG_WARNING, "remote delivery deferred: Peer did not provide certificate: %s", 168 ssl_errstr()); 169 } 170 X509_free(cert); 171 172 return (0); 173 } 174 175 /* 176 * hmac_md5() taken out of RFC 2104. This RFC was written by H. Krawczyk, 177 * M. Bellare and R. Canetti. 178 * 179 * text pointer to data stream 180 * text_len length of data stream 181 * key pointer to authentication key 182 * key_len length of authentication key 183 * digest caller digest to be filled int 184 */ 185 void 186 hmac_md5(unsigned char *text, int text_len, unsigned char *key, int key_len, 187 unsigned char* digest) 188 { 189 MD5_CTX context; 190 unsigned char k_ipad[65]; /* inner padding - 191 * key XORd with ipad 192 */ 193 unsigned char k_opad[65]; /* outer padding - 194 * key XORd with opad 195 */ 196 unsigned char tk[16]; 197 int i; 198 /* if key is longer than 64 bytes reset it to key=MD5(key) */ 199 if (key_len > 64) { 200 201 MD5_CTX tctx; 202 203 MD5_Init(&tctx); 204 MD5_Update(&tctx, key, key_len); 205 MD5_Final(tk, &tctx); 206 207 key = tk; 208 key_len = 16; 209 } 210 211 /* 212 * the HMAC_MD5 transform looks like: 213 * 214 * MD5(K XOR opad, MD5(K XOR ipad, text)) 215 * 216 * where K is an n byte key 217 * ipad is the byte 0x36 repeated 64 times 218 * 219 * opad is the byte 0x5c repeated 64 times 220 * and text is the data being protected 221 */ 222 223 /* start out by storing key in pads */ 224 bzero( k_ipad, sizeof k_ipad); 225 bzero( k_opad, sizeof k_opad); 226 bcopy( key, k_ipad, key_len); 227 bcopy( key, k_opad, key_len); 228 229 /* XOR key with ipad and opad values */ 230 for (i=0; i<64; i++) { 231 k_ipad[i] ^= 0x36; 232 k_opad[i] ^= 0x5c; 233 } 234 /* 235 * perform inner MD5 236 */ 237 MD5_Init(&context); /* init context for 1st 238 * pass */ 239 MD5_Update(&context, k_ipad, 64); /* start with inner pad */ 240 MD5_Update(&context, text, text_len); /* then text of datagram */ 241 MD5_Final(digest, &context); /* finish up 1st pass */ 242 /* 243 * perform outer MD5 244 */ 245 MD5_Init(&context); /* init context for 2nd 246 * pass */ 247 MD5_Update(&context, k_opad, 64); /* start with outer pad */ 248 MD5_Update(&context, digest, 16); /* then results of 1st 249 * hash */ 250 MD5_Final(digest, &context); /* finish up 2nd pass */ 251 } 252 253 /* 254 * CRAM-MD5 authentication 255 */ 256 int 257 smtp_auth_md5(int fd, char *login, char *password) 258 { 259 unsigned char digest[BUF_SIZE]; 260 char buffer[BUF_SIZE], ascii_digest[33]; 261 char *temp; 262 int len, i; 263 static char hextab[] = "0123456789abcdef"; 264 265 temp = calloc(BUF_SIZE, 1); 266 memset(buffer, 0, sizeof(buffer)); 267 memset(digest, 0, sizeof(digest)); 268 memset(ascii_digest, 0, sizeof(ascii_digest)); 269 270 /* Send AUTH command according to RFC 2554 */ 271 send_remote_command(fd, "AUTH CRAM-MD5"); 272 if (read_remote(fd, sizeof(buffer), buffer) != 3) { 273 syslog(LOG_DEBUG, "smarthost authentication:" 274 " AUTH cram-md5 not available: %s", neterr); 275 /* if cram-md5 is not available */ 276 free(temp); 277 return (-1); 278 } 279 280 /* skip 3 char status + 1 char space */ 281 base64_decode(buffer + 4, temp); 282 hmac_md5((unsigned char *)temp, strlen(temp), 283 (unsigned char *)password, strlen(password), digest); 284 free(temp); 285 286 ascii_digest[32] = 0; 287 for (i = 0; i < 16; i++) { 288 ascii_digest[2*i] = hextab[digest[i] >> 4]; 289 ascii_digest[2*i+1] = hextab[digest[i] & 15]; 290 } 291 292 /* prepare answer */ 293 snprintf(buffer, BUF_SIZE, "%s %s", login, ascii_digest); 294 295 /* encode answer */ 296 len = base64_encode(buffer, strlen(buffer), &temp); 297 if (len < 0) { 298 syslog(LOG_ERR, "can not encode auth reply: %m"); 299 return (-1); 300 } 301 302 /* send answer */ 303 send_remote_command(fd, "%s", temp); 304 free(temp); 305 if (read_remote(fd, 0, NULL) != 2) { 306 syslog(LOG_WARNING, "remote delivery deferred:" 307 " AUTH cram-md5 failed: %s", neterr); 308 return (-2); 309 } 310 311 return (0); 312 } 313