crypto/external/bsd/openssh/dist/kexdhs.c

   1 /*      $NetBSD: kexdhs.c,v 1.1.1.2 2009/12/27 01:06:56 christos Exp $  */
   2 /* $OpenBSD: kexdhs.c,v 1.10 2009/06/21 07:37:15 dtucker Exp $ */
   3 /*
   4  * Copyright (c) 2001 Markus Friedl.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include "includes.h"
  28 __RCSID("$NetBSD: kexdhs.c,v 1.2 2009/06/07 22:38:46 christos Exp $");
  29 #include <sys/types.h>
  30 #include <string.h>
  31 #include <signal.h>
  32
  33 #include "xmalloc.h"
  34 #include "buffer.h"
  35 #include "key.h"
  36 #include "cipher.h"
  37 #include "kex.h"
  38 #include "log.h"
  39 #include "packet.h"
  40 #include "dh.h"
  41 #include "ssh2.h"
  42 #ifdef GSSAPI
  43 #include "ssh-gss.h"
  44 #endif
  45 #include "monitor_wrap.h"
  46
  47 void
  48 kexdh_server(Kex *kex)
  49 {
  50         BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
  51         DH *dh = NULL;  /* XXX: GCC */
  52         Key *server_host_key;
  53         u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
  54         u_int sbloblen, klen, hashlen, slen;
  55         int kout;
  56
  57         /* generate server DH public key */
  58         switch (kex->kex_type) {
  59         case KEX_DH_GRP1_SHA1:
  60                 dh = dh_new_group1();
  61                 break;
  62         case KEX_DH_GRP14_SHA1:
  63                 dh = dh_new_group14();
  64                 break;
  65         default:
  66                 fatal("%s: Unexpected KEX type %d", __func__, kex->kex_type);
  67         }
  68         dh_gen_key(dh, kex->we_need * 8);
  69
  70         debug("expecting SSH2_MSG_KEXDH_INIT");
  71         packet_read_expect(SSH2_MSG_KEXDH_INIT);
  72
  73         if (kex->load_host_key == NULL)
  74                 fatal("Cannot load hostkey");
  75         server_host_key = kex->load_host_key(kex->hostkey_type);
  76         if (server_host_key == NULL)
  77                 fatal("Unsupported hostkey type %d", kex->hostkey_type);
  78
  79         /* key, cert */
  80         if ((dh_client_pub = BN_new()) == NULL)
  81                 fatal("dh_client_pub == NULL");
  82         packet_get_bignum2(dh_client_pub);
  83         packet_check_eom();
  84
  85 #ifdef DEBUG_KEXDH
  86         fprintf(stderr, "dh_client_pub= ");
  87         BN_print_fp(stderr, dh_client_pub);
  88         fprintf(stderr, "\n");
  89         debug("bits %d", BN_num_bits(dh_client_pub));
  90 #endif
  91
  92 #ifdef DEBUG_KEXDH
  93         DHparams_print_fp(stderr, dh);
  94         fprintf(stderr, "pub= ");
  95         BN_print_fp(stderr, dh->pub_key);
  96         fprintf(stderr, "\n");
  97 #endif
  98         if (!dh_pub_is_valid(dh, dh_client_pub))
  99                 packet_disconnect("bad client public DH value");
 100
 101         klen = DH_size(dh);
 102         kbuf = xmalloc(klen);
 103         if ((kout = DH_compute_key(kbuf, dh_client_pub, dh)) < 0)
 104                 fatal("DH_compute_key: failed");
 105 #ifdef DEBUG_KEXDH
 106         dump_digest("shared secret", kbuf, kout);
 107 #endif
 108         if ((shared_secret = BN_new()) == NULL)
 109                 fatal("kexdh_server: BN_new failed");
 110         if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
 111                 fatal("kexdh_server: BN_bin2bn failed");
 112         memset(kbuf, 0, klen);
 113         xfree(kbuf);
 114
 115         key_to_blob(server_host_key, &server_host_key_blob, &sbloblen);
 116
 117         /* calc H */
 118         kex_dh_hash(
 119             kex->client_version_string,
 120             kex->server_version_string,
 121             buffer_ptr(&kex->peer), buffer_len(&kex->peer),
 122             buffer_ptr(&kex->my), buffer_len(&kex->my),
 123             server_host_key_blob, sbloblen,
 124             dh_client_pub,
 125             dh->pub_key,
 126             shared_secret,
 127             &hash, &hashlen
 128         );
 129         BN_clear_free(dh_client_pub);
 130
 131         /* save session id := H */
 132         if (kex->session_id == NULL) {
 133                 kex->session_id_len = hashlen;
 134                 kex->session_id = xmalloc(kex->session_id_len);
 135                 memcpy(kex->session_id, hash, kex->session_id_len);
 136         }
 137
 138         /* sign H */
 139         if (PRIVSEP(key_sign(server_host_key, &signature, &slen, hash,
 140             hashlen)) < 0)
 141                 fatal("kexdh_server: key_sign failed");
 142
 143         /* destroy_sensitive_data(); */
 144
 145         /* send server hostkey, DH pubkey 'f' and singed H */
 146         packet_start(SSH2_MSG_KEXDH_REPLY);
 147         packet_put_string(server_host_key_blob, sbloblen);
 148         packet_put_bignum2(dh->pub_key);        /* f */
 149         packet_put_string(signature, slen);
 150         packet_send();
 151
 152         xfree(signature);
 153         xfree(server_host_key_blob);
 154         /* have keys, free DH */
 155         DH_free(dh);
 156
 157         kex_derive_keys(kex, hash, hashlen, shared_secret);
 158         BN_clear_free(shared_secret);
 159         kex_finish(kex);
 160 }