+++ /dev/null
-/*
- * Copyright (c) 2001-2005 Simon Wilkinson. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
- * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
- * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
- * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#include "includes.h"
-
-#ifdef GSSAPI
-
-#include <openssl/crypto.h>
-#include <openssl/bn.h>
-
-#include "xmalloc.h"
-#include "buffer.h"
-#include "bufaux.h"
-#include "kex.h"
-#include "log.h"
-#include "packet.h"
-#include "dh.h"
-#include "ssh2.h"
-#include "ssh-gss.h"
-#include "monitor_wrap.h"
-
-void
-kexgss_server(Kex *kex)
-{
- OM_uint32 maj_status, min_status;
-
- /*
- * Some GSSAPI implementations use the input value of ret_flags (an
- * output variable) as a means of triggering mechanism specific
- * features. Initializing it to zero avoids inadvertently
- * activating this non-standard behaviour.
- */
-
- OM_uint32 ret_flags = 0;
- gss_buffer_desc gssbuf, recv_tok, msg_tok;
- gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
- Gssctxt *ctxt = NULL;
- unsigned int klen, kout;
- unsigned char *kbuf, *hash;
- DH *dh;
- int min = -1, max = -1, nbits = -1;
- BIGNUM *shared_secret = NULL;
- BIGNUM *dh_client_pub = NULL;
- int type = 0;
- int gex;
- u_int slen;
- gss_OID oid;
-
- /* Initialise GSSAPI */
-
- /* If we're rekeying, privsep means that some of the private structures
- * in the GSSAPI code are no longer available. This kludges them back
- * into life
- */
- if (!ssh_gssapi_oid_table_ok())
- ssh_gssapi_server_mechanisms();
-
- debug2("%s: Identifying %s", __func__, kex->name);
- oid = ssh_gssapi_id_kex(NULL, kex->name, &gex);
- if (oid == NULL)
- fatal("Unknown gssapi mechanism");
-
- debug2("%s: Acquiring credentials", __func__);
-
- if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt, oid))))
- fatal("Unable to acquire credentials for the server");
-
- if (gex) {
- debug("Doing group exchange");
- packet_read_expect(SSH2_MSG_KEXGSS_GROUPREQ);
- min = packet_get_int();
- nbits = packet_get_int();
- max = packet_get_int();
- min = MAX(DH_GRP_MIN, min);
- max = MIN(DH_GRP_MAX, max);
- packet_check_eom();
- if (max < min || nbits < min || max < nbits)
- fatal("GSS_GEX, bad parameters: %d !< %d !< %d",
- min, nbits, max);
- dh = PRIVSEP(choose_dh(min, nbits, max));
- if (dh == NULL)
- packet_disconnect("Protocol error: no matching group found");
-
- packet_start(SSH2_MSG_KEXGSS_GROUP);
- packet_put_bignum2(dh->p);
- packet_put_bignum2(dh->g);
- packet_send();
-
- packet_write_wait();
-
- } else {
- dh = dh_new_group1();
- }
- dh_gen_key(dh, kex->we_need * 8);
-
- do {
- debug("Wait SSH2_MSG_GSSAPI_INIT");
- type = packet_read();
- switch(type) {
- case SSH2_MSG_KEXGSS_INIT:
- if (dh_client_pub != NULL)
- fatal("Received KEXGSS_INIT after initialising");
- recv_tok.value = packet_get_string(&slen);
- recv_tok.length = slen;
-
- if ((dh_client_pub = BN_new()) == NULL)
- fatal("dh_client_pub == NULL");
-
- packet_get_bignum2(dh_client_pub);
-
- /* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
- break;
- case SSH2_MSG_KEXGSS_CONTINUE:
- recv_tok.value = packet_get_string(&slen);
- recv_tok.length = slen;
- break;
- default:
- packet_disconnect(
- "Protocol error: didn't expect packet type %d",
- type);
- }
-
- maj_status = PRIVSEP(ssh_gssapi_accept_ctx(ctxt, &recv_tok,
- &send_tok, &ret_flags));
-
- xfree(recv_tok.value);
-
- if (maj_status != GSS_S_COMPLETE && send_tok.length == 0)
- fatal("Zero length token output when incomplete");
-
- if (dh_client_pub == NULL)
- fatal("No client public key");
-
- if (maj_status & GSS_S_CONTINUE_NEEDED) {
- debug("Sending GSSAPI_CONTINUE");
- packet_start(SSH2_MSG_KEXGSS_CONTINUE);
- packet_put_string(send_tok.value, send_tok.length);
- packet_send();
- gss_release_buffer(&min_status, &send_tok);
- }
- } while (maj_status & GSS_S_CONTINUE_NEEDED);
-
- if (GSS_ERROR(maj_status)) {
- if (send_tok.length > 0) {
- packet_start(SSH2_MSG_KEXGSS_CONTINUE);
- packet_put_string(send_tok.value, send_tok.length);
- packet_send();
- }
- fatal("accept_ctx died");
- }
-
- if (!(ret_flags & GSS_C_MUTUAL_FLAG))
- fatal("Mutual Authentication flag wasn't set");
-
- if (!(ret_flags & GSS_C_INTEG_FLAG))
- fatal("Integrity flag wasn't set");
-
- if (!dh_pub_is_valid(dh, dh_client_pub))
- packet_disconnect("bad client public DH value");
-
- klen = DH_size(dh);
- kbuf = xmalloc(klen);
- kout = DH_compute_key(kbuf, dh_client_pub, dh);
-
- shared_secret = BN_new();
- BN_bin2bn(kbuf, kout, shared_secret);
- memset(kbuf, 0, klen);
- xfree(kbuf);
-
- if (gex) {
- hash = kexgex_hash(
- kex->client_version_string, kex->server_version_string,
- buffer_ptr(&kex->peer), buffer_len(&kex->peer),
- buffer_ptr(&kex->my), buffer_len(&kex->my),
- NULL, 0,
- min, nbits, max,
- dh->p, dh->g,
- dh_client_pub,
- dh->pub_key,
- shared_secret
- );
- }
- else {
- /* The GSSAPI hash is identical to the Diffie Helman one */
- hash = kex_dh_hash(
- kex->client_version_string, kex->server_version_string,
- buffer_ptr(&kex->peer), buffer_len(&kex->peer),
- buffer_ptr(&kex->my), buffer_len(&kex->my),
- NULL, 0, /* Change this if we start sending host keys */
- dh_client_pub, dh->pub_key, shared_secret
- );
- }
- BN_free(dh_client_pub);
-
- if (kex->session_id == NULL) {
- kex->session_id_len = 20;
- kex->session_id = xmalloc(kex->session_id_len);
- memcpy(kex->session_id, hash, kex->session_id_len);
- }
-
- gssbuf.value = hash;
- gssbuf.length = 20; /* Hashlen appears to always be 20 */
-
- if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt,&gssbuf,&msg_tok))))
- fatal("Couldn't get MIC");
-
- packet_start(SSH2_MSG_KEXGSS_COMPLETE);
- packet_put_bignum2(dh->pub_key);
- packet_put_string((char *)msg_tok.value,msg_tok.length);
-
- if (send_tok.length != 0) {
- packet_put_char(1); /* true */
- packet_put_string((char *)send_tok.value, send_tok.length);
- } else {
- packet_put_char(0); /* false */
- }
- packet_send();
-
- gss_release_buffer(&min_status, &send_tok);
- gss_release_buffer(&min_status, &msg_tok);
-
- if (gss_kex_context == NULL)
- gss_kex_context = ctxt;
- else
- ssh_gssapi_delete_ctx(&ctxt);
-
- DH_free(dh);
-
- kex_derive_keys(kex, hash, shared_secret);
- BN_clear_free(shared_secret);
- kex_finish(kex);
-}
-#endif /* GSSAPI */
andersk / gssapi-openssh.git / blobdiff