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