crypto.c

   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  * $DragonFly: src/libexec/dma/crypto.c,v 1.4 2008/09/30 17:47:21 swildner Exp $
  36  */
  37
  38 #ifdef HAVE_CRYPTO
  39
  40 #include <openssl/x509.h>
  41 #include <openssl/md5.h>
  42 #include <openssl/ssl.h>
  43 #include <openssl/err.h>
  44 #include <openssl/pem.h>
  45 #include <openssl/rand.h>
  46
  47 #include <syslog.h>
  48
  49 #include "dma.h"
  50
  51 extern struct config *config;
  52
  53 static int
  54 init_cert_file(struct qitem *it, SSL_CTX *ctx, const char *path)
  55 {
  56         int error;
  57
  58         /* Load certificate into ctx */
  59         error = SSL_CTX_use_certificate_chain_file(ctx, path);
  60         if (error < 1) {
  61                 syslog(LOG_ERR, "%s: SSL: Cannot load certificate: %s",
  62                         it->queueid, path);
  63                 return (-1);
  64         }
  65
  66         /* Add private key to ctx */
  67         error = SSL_CTX_use_PrivateKey_file(ctx, path, SSL_FILETYPE_PEM);
  68         if (error < 1) {
  69                 syslog(LOG_ERR, "%s: SSL: Cannot load private key: %s",
  70                         it->queueid, path);
  71                 return (-1);
  72         }
  73
  74         /*
  75          * Check the consistency of a private key with the corresponding
  76          * certificate
  77          */
  78         error = SSL_CTX_check_private_key(ctx);
  79         if (error < 1) {
  80                 syslog(LOG_ERR, "%s: SSL: Cannot check private key: %s",
  81                         it->queueid, path);
  82                 return (-1);
  83         }
  84
  85         return (0);
  86 }
  87
  88 int
  89 smtp_init_crypto(struct qitem *it, int fd, int feature)
  90 {
  91         SSL_CTX *ctx = NULL;
  92         SSL_METHOD *meth = NULL;
  93         X509 *cert;
  94         int error;
  95
  96         /* Init SSL library */
  97         SSL_library_init();
  98
  99         meth = TLSv1_client_method();
 100
 101         ctx = SSL_CTX_new(meth);
 102         if (ctx == NULL) {
 103                 syslog(LOG_ERR, "%s: remote delivery deferred:"
 104                        " SSL init failed: %m", it->queueid);
 105                 return (2);
 106         }
 107
 108         /* User supplied a certificate */
 109         if (config->certfile != NULL)
 110                 init_cert_file(it, ctx, config->certfile);
 111
 112         /*
 113          * If the user wants STARTTLS, we have to send EHLO here
 114          */
 115         if (((feature & SECURETRANS) != 0) &&
 116              (feature & STARTTLS) != 0) {
 117                 /* TLS init phase, disable SSL_write */
 118                 config->features |= NOSSL;
 119
 120                 send_remote_command(fd, "EHLO %s", hostname());
 121                 if (read_remote(fd, 0, NULL) == 2) {
 122                         send_remote_command(fd, "STARTTLS");
 123                         if (read_remote(fd, 0, NULL) != 2) {
 124                                 syslog(LOG_ERR, "%s: remote delivery failed:"
 125                                   " STARTTLS not available: %m", it->queueid);
 126                                 config->features &= ~NOSSL;
 127                                 return (-1);
 128                         }
 129                 }
 130                 /* End of TLS init phase, enable SSL_write/read */
 131                 config->features &= ~NOSSL;
 132         }
 133
 134         config->ssl = SSL_new(ctx);
 135         if (config->ssl == NULL) {
 136                 syslog(LOG_ERR, "%s: remote delivery deferred:"
 137                        " SSL struct creation failed:", it->queueid);
 138                 return (2);
 139         }
 140
 141         /* Set ssl to work in client mode */
 142         SSL_set_connect_state(config->ssl);
 143
 144         /* Set fd for SSL in/output */
 145         error = SSL_set_fd(config->ssl, fd);
 146         if (error == 0) {
 147                 error = SSL_get_error(config->ssl, error);
 148                 syslog(LOG_ERR, "%s: remote delivery deferred:"
 149                        " SSL set fd failed (%d): %m", it->queueid, error);
 150                 return (2);
 151         }
 152
 153         /* Open SSL connection */
 154         error = SSL_connect(config->ssl);
 155         if (error < 0) {
 156                 syslog(LOG_ERR, "%s: remote delivery failed:"
 157                        " SSL handshake fataly failed: %m", it->queueid);
 158                 return (-1);
 159         }
 160
 161         /* Get peer certificate */
 162         cert = SSL_get_peer_certificate(config->ssl);
 163         if (cert == NULL) {
 164                 syslog(LOG_ERR, "%s: remote delivery deferred:"
 165                        " Peer did not provied certificate: %m", it->queueid);
 166         }
 167         X509_free(cert);
 168
 169         return (0);
 170 }
 171
 172 /*
 173  * hmac_md5() taken out of RFC 2104.  This RFC was written by H. Krawczyk,
 174  * M. Bellare and R. Canetti.
 175  *
 176  * text      pointer to data stream
 177  * text_len  length of data stream
 178  * key       pointer to authentication key
 179  * key_len   length of authentication key
 180  * digest    caller digest to be filled int
 181  */
 182 void
 183 hmac_md5(unsigned char *text, int text_len, unsigned char *key, int key_len,
 184     caddr_t digest)
 185 {
 186         MD5_CTX context;
 187         unsigned char k_ipad[65];    /* inner padding -
 188                                       * key XORd with ipad
 189                                       */
 190         unsigned char k_opad[65];    /* outer padding -
 191                                       * key XORd with opad
 192                                       */
 193         unsigned char tk[16];
 194         int i;
 195         /* if key is longer than 64 bytes reset it to key=MD5(key) */
 196         if (key_len > 64) {
 197
 198                 MD5_CTX      tctx;
 199
 200                 MD5_Init(&tctx);
 201                 MD5_Update(&tctx, key, key_len);
 202                 MD5_Final(tk, &tctx);
 203
 204                 key = tk;
 205                 key_len = 16;
 206         }
 207
 208         /*
 209          * the HMAC_MD5 transform looks like:
 210          *
 211          * MD5(K XOR opad, MD5(K XOR ipad, text))
 212          *
 213          * where K is an n byte key
 214          * ipad is the byte 0x36 repeated 64 times
 215          *
 216          * opad is the byte 0x5c repeated 64 times
 217          * and text is the data being protected
 218          */
 219
 220         /* start out by storing key in pads */
 221         bzero( k_ipad, sizeof k_ipad);
 222         bzero( k_opad, sizeof k_opad);
 223         bcopy( key, k_ipad, key_len);
 224         bcopy( key, k_opad, key_len);
 225
 226         /* XOR key with ipad and opad values */
 227         for (i=0; i<64; i++) {
 228                 k_ipad[i] ^= 0x36;
 229                 k_opad[i] ^= 0x5c;
 230         }
 231         /*
 232          * perform inner MD5
 233          */
 234         MD5_Init(&context);                   /* init context for 1st
 235                                               * pass */
 236         MD5_Update(&context, k_ipad, 64);     /* start with inner pad */
 237         MD5_Update(&context, text, text_len); /* then text of datagram */
 238         MD5_Final(digest, &context);          /* finish up 1st pass */
 239         /*
 240          * perform outer MD5
 241          */
 242         MD5_Init(&context);                   /* init context for 2nd
 243                                               * pass */
 244         MD5_Update(&context, k_opad, 64);     /* start with outer pad */
 245         MD5_Update(&context, digest, 16);     /* then results of 1st
 246                                               * hash */
 247         MD5_Final(digest, &context);          /* finish up 2nd pass */
 248 }
 249
 250 /*
 251  * CRAM-MD5 authentication
 252  */
 253 int
 254 smtp_auth_md5(struct qitem *it, int fd, char *login, char *password)
 255 {
 256         unsigned char buffer[BUF_SIZE], digest[BUF_SIZE], ascii_digest[33];
 257         char *temp;
 258         int len, i;
 259         static char hextab[] = "0123456789abcdef";
 260
 261         temp = calloc(BUF_SIZE, 1);
 262         memset(buffer, 0, sizeof(buffer));
 263         memset(digest, 0, sizeof(digest));
 264         memset(ascii_digest, 0, sizeof(ascii_digest));
 265
 266         /* Send AUTH command according to RFC 2554 */
 267         send_remote_command(fd, "AUTH CRAM-MD5");
 268         if (read_remote(fd, sizeof(buffer), buffer) != 3) {
 269                 syslog(LOG_ERR, "%s: smarthost authentification:"
 270                        " AUTH cram-md5 not available: %m", it->queueid);
 271                 /* if cram-md5 is not available */
 272                 return (-1);
 273         }
 274
 275         /* skip 3 char status + 1 char space */
 276         base64_decode(buffer + 4, temp);
 277         hmac_md5(temp, strlen(temp), password, strlen(password), digest);
 278
 279         ascii_digest[32] = 0;
 280         for (i = 0; i < 16; i++) {
 281                 ascii_digest[2*i] = hextab[digest[i] >> 4];
 282                 ascii_digest[2*i+1] = hextab[digest[i] & 15];
 283         }
 284
 285         /* prepare answer */
 286         snprintf(buffer, BUF_SIZE, "%s %s", login, ascii_digest);
 287
 288         /* temp will be allocated inside base64_encode again */
 289         free(temp);
 290         /* encode answer */
 291         len = base64_encode(buffer, strlen(buffer), &temp);
 292         if (len <= 0)
 293                 return (-1);
 294
 295         /* send answer */
 296         send_remote_command(fd, "%s", temp);
 297         if (read_remote(fd, 0, NULL) != 2) {
 298                 syslog(LOG_ERR, "%s: remote delivery deferred:"
 299                                 " AUTH cram-md5 failed: %m", it->queueid);
 300                 return (-2);
 301         }
 302
 303         return (0);
 304 }
 305
 306 #endif /* HAVE_CRYPTO */