libexec/dma/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
  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         SSL_METHOD *meth = NULL;
  84         X509 *cert;
  85         int error;
  86
  87         /* XXX clean up on error/close */
  88         /* Init SSL library */
  89         SSL_library_init();
  90         SSL_load_error_strings();
  91
  92         meth = TLSv1_client_method();
  93
  94         ctx = SSL_CTX_new(meth);
  95         if (ctx == NULL) {
  96                 syslog(LOG_WARNING, "remote delivery deferred: SSL init failed: %s", ssl_errstr());
  97                 return (1);
  98         }
  99
 100         /* User supplied a certificate */
 101         if (config.certfile != NULL) {
 102                 error = init_cert_file(ctx, config.certfile);
 103                 if (error) {
 104                         syslog(LOG_WARNING, "remote delivery deferred");
 105                         return (1);
 106                 }
 107         }
 108
 109         /*
 110          * If the user wants STARTTLS, we have to send EHLO here
 111          */
 112         if (((feature & SECURETRANS) != 0) &&
 113              (feature & STARTTLS) != 0) {
 114                 /* TLS init phase, disable SSL_write */
 115                 config.features |= NOSSL;
 116
 117                 send_remote_command(fd, "EHLO %s", hostname());
 118                 if (read_remote(fd, 0, NULL) == 2) {
 119                         send_remote_command(fd, "STARTTLS");
 120                         if (read_remote(fd, 0, NULL) != 2) {
 121                                 syslog(LOG_ERR, "remote delivery deferred:"
 122                                   " STARTTLS not available: %s", neterr);
 123                                 config.features &= ~NOSSL;
 124                                 return (1);
 125                         }
 126                 }
 127                 /* End of TLS init phase, enable SSL_write/read */
 128                 config.features &= ~NOSSL;
 129         }
 130
 131         config.ssl = SSL_new(ctx);
 132         if (config.ssl == NULL) {
 133                 syslog(LOG_NOTICE, "remote delivery deferred: SSL struct creation failed: %s",
 134                        ssl_errstr());
 135                 return (1);
 136         }
 137
 138         /* Set ssl to work in client mode */
 139         SSL_set_connect_state(config.ssl);
 140
 141         /* Set fd for SSL in/output */
 142         error = SSL_set_fd(config.ssl, fd);
 143         if (error == 0) {
 144                 syslog(LOG_NOTICE, "remote delivery deferred: SSL set fd failed: %s",
 145                        ssl_errstr());
 146                 return (1);
 147         }
 148
 149         /* Open SSL connection */
 150         error = SSL_connect(config.ssl);
 151         if (error < 0) {
 152                 syslog(LOG_ERR, "remote delivery deferred: SSL handshake failed fatally: %s",
 153                        ssl_errstr());
 154                 return (1);
 155         }
 156
 157         /* Get peer certificate */
 158         cert = SSL_get_peer_certificate(config.ssl);
 159         if (cert == NULL) {
 160                 syslog(LOG_WARNING, "remote delivery deferred: Peer did not provide certificate: %s",
 161                        ssl_errstr());
 162         }
 163         X509_free(cert);
 164
 165         return (0);
 166 }
 167
 168 /*
 169  * hmac_md5() taken out of RFC 2104.  This RFC was written by H. Krawczyk,
 170  * M. Bellare and R. Canetti.
 171  *
 172  * text      pointer to data stream
 173  * text_len  length of data stream
 174  * key       pointer to authentication key
 175  * key_len   length of authentication key
 176  * digest    caller digest to be filled int
 177  */
 178 void
 179 hmac_md5(unsigned char *text, int text_len, unsigned char *key, int key_len,
 180     caddr_t digest)
 181 {
 182         MD5_CTX context;
 183         unsigned char k_ipad[65];    /* inner padding -
 184                                       * key XORd with ipad
 185                                       */
 186         unsigned char k_opad[65];    /* outer padding -
 187                                       * key XORd with opad
 188                                       */
 189         unsigned char tk[16];
 190         int i;
 191         /* if key is longer than 64 bytes reset it to key=MD5(key) */
 192         if (key_len > 64) {
 193
 194                 MD5_CTX      tctx;
 195
 196                 MD5_Init(&tctx);
 197                 MD5_Update(&tctx, key, key_len);
 198                 MD5_Final(tk, &tctx);
 199
 200                 key = tk;
 201                 key_len = 16;
 202         }
 203
 204         /*
 205          * the HMAC_MD5 transform looks like:
 206          *
 207          * MD5(K XOR opad, MD5(K XOR ipad, text))
 208          *
 209          * where K is an n byte key
 210          * ipad is the byte 0x36 repeated 64 times
 211          *
 212          * opad is the byte 0x5c repeated 64 times
 213          * and text is the data being protected
 214          */
 215
 216         /* start out by storing key in pads */
 217         bzero( k_ipad, sizeof k_ipad);
 218         bzero( k_opad, sizeof k_opad);
 219         bcopy( key, k_ipad, key_len);
 220         bcopy( key, k_opad, key_len);
 221
 222         /* XOR key with ipad and opad values */
 223         for (i=0; i<64; i++) {
 224                 k_ipad[i] ^= 0x36;
 225                 k_opad[i] ^= 0x5c;
 226         }
 227         /*
 228          * perform inner MD5
 229          */
 230         MD5_Init(&context);                   /* init context for 1st
 231                                               * pass */
 232         MD5_Update(&context, k_ipad, 64);     /* start with inner pad */
 233         MD5_Update(&context, text, text_len); /* then text of datagram */
 234         MD5_Final(digest, &context);          /* finish up 1st pass */
 235         /*
 236          * perform outer MD5
 237          */
 238         MD5_Init(&context);                   /* init context for 2nd
 239                                               * pass */
 240         MD5_Update(&context, k_opad, 64);     /* start with outer pad */
 241         MD5_Update(&context, digest, 16);     /* then results of 1st
 242                                               * hash */
 243         MD5_Final(digest, &context);          /* finish up 2nd pass */
 244 }
 245
 246 /*
 247  * CRAM-MD5 authentication
 248  */
 249 int
 250 smtp_auth_md5(int fd, char *login, char *password)
 251 {
 252         unsigned char buffer[BUF_SIZE], digest[BUF_SIZE], ascii_digest[33];
 253         char *temp;
 254         int len, i;
 255         static char hextab[] = "0123456789abcdef";
 256
 257         temp = calloc(BUF_SIZE, 1);
 258         memset(buffer, 0, sizeof(buffer));
 259         memset(digest, 0, sizeof(digest));
 260         memset(ascii_digest, 0, sizeof(ascii_digest));
 261
 262         /* Send AUTH command according to RFC 2554 */
 263         send_remote_command(fd, "AUTH CRAM-MD5");
 264         if (read_remote(fd, sizeof(buffer), buffer) != 3) {
 265                 syslog(LOG_DEBUG, "smarthost authentification:"
 266                        " AUTH cram-md5 not available: %s", neterr);
 267                 /* if cram-md5 is not available */
 268                 return (-1);
 269         }
 270
 271         /* skip 3 char status + 1 char space */
 272         base64_decode(buffer + 4, temp);
 273         hmac_md5(temp, strlen(temp), password, strlen(password), digest);
 274         free(temp);
 275
 276         ascii_digest[32] = 0;
 277         for (i = 0; i < 16; i++) {
 278                 ascii_digest[2*i] = hextab[digest[i] >> 4];
 279                 ascii_digest[2*i+1] = hextab[digest[i] & 15];
 280         }
 281
 282         /* prepare answer */
 283         snprintf(buffer, BUF_SIZE, "%s %s", login, ascii_digest);
 284
 285         /* encode answer */
 286         len = base64_encode(buffer, strlen(buffer), &temp);
 287         if (len < 0) {
 288                 syslog(LOG_ERR, "can not encode auth reply: %m");
 289                 return (-1);
 290         }
 291
 292         /* send answer */
 293         send_remote_command(fd, "%s", temp);
 294         free(temp);
 295         if (read_remote(fd, 0, NULL) != 2) {
 296                 syslog(LOG_WARNING, "remote delivery deferred:"
 297                                 " AUTH cram-md5 failed: %s", neterr);
 298                 return (-2);
 299         }
 300
 301         return (0);
 302 }