Annotation of src/crypto/external/bsd/openssh/dist/kexgexs.c, Revision 1.1
1.1 ! christos 1: /* $NetBSD$ */
! 2: /* $OpenBSD: kexgexs.c,v 1.11 2009/01/01 21:17:36 djm Exp $ */
! 3: /*
! 4: * Copyright (c) 2000 Niels Provos. All rights reserved.
! 5: * Copyright (c) 2001 Markus Friedl. All rights reserved.
! 6: *
! 7: * Redistribution and use in source and binary forms, with or without
! 8: * modification, are permitted provided that the following conditions
! 9: * are met:
! 10: * 1. Redistributions of source code must retain the above copyright
! 11: * notice, this list of conditions and the following disclaimer.
! 12: * 2. Redistributions in binary form must reproduce the above copyright
! 13: * notice, this list of conditions and the following disclaimer in the
! 14: * documentation and/or other materials provided with the distribution.
! 15: *
! 16: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
! 17: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
! 18: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
! 19: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
! 20: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
! 21: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
! 22: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
! 23: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
! 24: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
! 25: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
! 26: */
! 27:
! 28: #include <sys/param.h>
! 29:
! 30: #include <stdio.h>
! 31: #include <string.h>
! 32: #include <signal.h>
! 33:
! 34: #include "xmalloc.h"
! 35: #include "buffer.h"
! 36: #include "key.h"
! 37: #include "cipher.h"
! 38: #include "kex.h"
! 39: #include "log.h"
! 40: #include "packet.h"
! 41: #include "dh.h"
! 42: #include "ssh2.h"
! 43: #include "compat.h"
! 44: #ifdef GSSAPI
! 45: #include "ssh-gss.h"
! 46: #endif
! 47: #include "monitor_wrap.h"
! 48:
! 49: void
! 50: kexgex_server(Kex *kex)
! 51: {
! 52: BIGNUM *shared_secret = NULL, *dh_client_pub = NULL;
! 53: Key *server_host_key;
! 54: DH *dh;
! 55: u_char *kbuf, *hash, *signature = NULL, *server_host_key_blob = NULL;
! 56: u_int sbloblen, klen, slen, hashlen;
! 57: int omin = -1, min = -1, omax = -1, max = -1, onbits = -1, nbits = -1;
! 58: int type, kout;
! 59:
! 60: if (kex->load_host_key == NULL)
! 61: fatal("Cannot load hostkey");
! 62: server_host_key = kex->load_host_key(kex->hostkey_type);
! 63: if (server_host_key == NULL)
! 64: fatal("Unsupported hostkey type %d", kex->hostkey_type);
! 65:
! 66: type = packet_read();
! 67: switch (type) {
! 68: case SSH2_MSG_KEX_DH_GEX_REQUEST:
! 69: debug("SSH2_MSG_KEX_DH_GEX_REQUEST received");
! 70: omin = min = packet_get_int();
! 71: onbits = nbits = packet_get_int();
! 72: omax = max = packet_get_int();
! 73: min = MAX(DH_GRP_MIN, min);
! 74: max = MIN(DH_GRP_MAX, max);
! 75: nbits = MAX(DH_GRP_MIN, nbits);
! 76: nbits = MIN(DH_GRP_MAX, nbits);
! 77: break;
! 78: case SSH2_MSG_KEX_DH_GEX_REQUEST_OLD:
! 79: debug("SSH2_MSG_KEX_DH_GEX_REQUEST_OLD received");
! 80: onbits = nbits = packet_get_int();
! 81: /* unused for old GEX */
! 82: omin = min = DH_GRP_MIN;
! 83: omax = max = DH_GRP_MAX;
! 84: break;
! 85: default:
! 86: fatal("protocol error during kex, no DH_GEX_REQUEST: %d", type);
! 87: }
! 88: packet_check_eom();
! 89:
! 90: if (omax < omin || onbits < omin || omax < onbits)
! 91: fatal("DH_GEX_REQUEST, bad parameters: %d !< %d !< %d",
! 92: omin, onbits, omax);
! 93:
! 94: /* Contact privileged parent */
! 95: dh = PRIVSEP(choose_dh(min, nbits, max));
! 96: if (dh == NULL)
! 97: packet_disconnect("Protocol error: no matching DH grp found");
! 98:
! 99: debug("SSH2_MSG_KEX_DH_GEX_GROUP sent");
! 100: packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
! 101: packet_put_bignum2(dh->p);
! 102: packet_put_bignum2(dh->g);
! 103: packet_send();
! 104:
! 105: /* flush */
! 106: packet_write_wait();
! 107:
! 108: /* Compute our exchange value in parallel with the client */
! 109: dh_gen_key(dh, kex->we_need * 8);
! 110:
! 111: debug("expecting SSH2_MSG_KEX_DH_GEX_INIT");
! 112: packet_read_expect(SSH2_MSG_KEX_DH_GEX_INIT);
! 113:
! 114: /* key, cert */
! 115: if ((dh_client_pub = BN_new()) == NULL)
! 116: fatal("dh_client_pub == NULL");
! 117: packet_get_bignum2(dh_client_pub);
! 118: packet_check_eom();
! 119:
! 120: #ifdef DEBUG_KEXDH
! 121: fprintf(stderr, "dh_client_pub= ");
! 122: BN_print_fp(stderr, dh_client_pub);
! 123: fprintf(stderr, "\n");
! 124: debug("bits %d", BN_num_bits(dh_client_pub));
! 125: #endif
! 126:
! 127: #ifdef DEBUG_KEXDH
! 128: DHparams_print_fp(stderr, dh);
! 129: fprintf(stderr, "pub= ");
! 130: BN_print_fp(stderr, dh->pub_key);
! 131: fprintf(stderr, "\n");
! 132: #endif
! 133: if (!dh_pub_is_valid(dh, dh_client_pub))
! 134: packet_disconnect("bad client public DH value");
! 135:
! 136: klen = DH_size(dh);
! 137: kbuf = xmalloc(klen);
! 138: if ((kout = DH_compute_key(kbuf, dh_client_pub, dh)) < 0)
! 139: fatal("DH_compute_key: failed");
! 140: #ifdef DEBUG_KEXDH
! 141: dump_digest("shared secret", kbuf, kout);
! 142: #endif
! 143: if ((shared_secret = BN_new()) == NULL)
! 144: fatal("kexgex_server: BN_new failed");
! 145: if (BN_bin2bn(kbuf, kout, shared_secret) == NULL)
! 146: fatal("kexgex_server: BN_bin2bn failed");
! 147: memset(kbuf, 0, klen);
! 148: xfree(kbuf);
! 149:
! 150: key_to_blob(server_host_key, &server_host_key_blob, &sbloblen);
! 151:
! 152: if (type == SSH2_MSG_KEX_DH_GEX_REQUEST_OLD)
! 153: omin = min = omax = max = -1;
! 154:
! 155: /* calc H */
! 156: kexgex_hash(
! 157: kex->evp_md,
! 158: kex->client_version_string,
! 159: kex->server_version_string,
! 160: buffer_ptr(&kex->peer), buffer_len(&kex->peer),
! 161: buffer_ptr(&kex->my), buffer_len(&kex->my),
! 162: server_host_key_blob, sbloblen,
! 163: omin, onbits, omax,
! 164: dh->p, dh->g,
! 165: dh_client_pub,
! 166: dh->pub_key,
! 167: shared_secret,
! 168: &hash, &hashlen
! 169: );
! 170: BN_clear_free(dh_client_pub);
! 171:
! 172: /* save session id := H */
! 173: if (kex->session_id == NULL) {
! 174: kex->session_id_len = hashlen;
! 175: kex->session_id = xmalloc(kex->session_id_len);
! 176: memcpy(kex->session_id, hash, kex->session_id_len);
! 177: }
! 178:
! 179: /* sign H */
! 180: PRIVSEP(key_sign(server_host_key, &signature, &slen, hash, hashlen));
! 181:
! 182: /* destroy_sensitive_data(); */
! 183:
! 184: /* send server hostkey, DH pubkey 'f' and singed H */
! 185: debug("SSH2_MSG_KEX_DH_GEX_REPLY sent");
! 186: packet_start(SSH2_MSG_KEX_DH_GEX_REPLY);
! 187: packet_put_string(server_host_key_blob, sbloblen);
! 188: packet_put_bignum2(dh->pub_key); /* f */
! 189: packet_put_string(signature, slen);
! 190: packet_send();
! 191:
! 192: xfree(signature);
! 193: xfree(server_host_key_blob);
! 194: /* have keys, free DH */
! 195: DH_free(dh);
! 196:
! 197: kex_derive_keys(kex, hash, hashlen, shared_secret);
! 198: BN_clear_free(shared_secret);
! 199:
! 200: kex_finish(kex);
! 201: }
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