[gssapi-openssh.git] / openssh / kexgssc.c

/*
 * Copyright (c) 2001-2003 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"

void
kexgss_client(Kex *kex)
{
	gss_buffer_desc gssbuf,send_tok,recv_tok, msg_tok, *token_ptr;
	Gssctxt *ctxt;
	OM_uint32 maj_status, min_status, ret_flags;
	unsigned int klen, kout;
	DH *dh; 
	BIGNUM *dh_server_pub = 0;
	BIGNUM *shared_secret = 0;	
	unsigned char *kbuf;
	unsigned char *hash;
	unsigned char *serverhostkey;
	char *msg;
	char *lang;
	int type = 0;
	int first = 1;
	int slen = 0;
	
	/* Initialise our GSSAPI world */
	ssh_gssapi_build_ctx(&ctxt);
	if (ssh_gssapi_client_id_kex(ctxt,kex->name)==NULL) {
		fatal("Couldn't identify host exchange");
	}

	if (ssh_gssapi_import_name(ctxt,kex->host)) {
		fatal("Couldn't import hostname ");
	}
	
	/* This code should match that in ssh_dh1_client */
		
	/* Step 1 - e is dh->pub_key */
	dh = dh_new_group1();
	dh_gen_key(dh, kex->we_need * 8);

	/* This is f, we initialise it now to make life easier */
    	dh_server_pub = BN_new();
    	if (dh_server_pub == NULL) {
    		fatal("dh_server_pub == NULL");
    	}
    		
	token_ptr = GSS_C_NO_BUFFER;
			 
	do {
		debug("Calling gss_init_sec_context");
		
		maj_status=ssh_gssapi_init_ctx(ctxt,
					       kex->options.gss_deleg_creds,
					       token_ptr,&send_tok,
					       &ret_flags);

		if (GSS_ERROR(maj_status)) {
			if (send_tok.length!=0) {
				/* Hmmm - not sure about this */
				packet_start(SSH2_MSG_KEXGSS_CONTINUE);
				packet_put_string(send_tok.value,
						  send_tok.length);
			}			  
			fatal("gss_init_context failed");
		}

		/* If we've got an old receive buffer get rid of it */
		if (token_ptr != GSS_C_NO_BUFFER)
	  		(void) gss_release_buffer(&min_status, &recv_tok);
 	
		
		if (maj_status == GSS_S_COMPLETE) {
			/* If mutual state flag is not true, kex fails */
			if (!(ret_flags & GSS_C_MUTUAL_FLAG)) {
				fatal("Mutual authentication failed");
			}
			/* If integ avail flag is not true kex fails */
			if (!(ret_flags & GSS_C_INTEG_FLAG)) {
				fatal("Integrity check failed");
			}
		}
		
		/* If we have data to send, then the last message that we
		 * received cannot have been a 'complete'. */
		if (send_tok.length !=0) {
			if (first) {
				packet_start(SSH2_MSG_KEXGSS_INIT);
				packet_put_string(send_tok.value,
					  	  send_tok.length);
				packet_put_bignum2(dh->pub_key);
				first=0;
			} else {
				packet_start(SSH2_MSG_KEXGSS_CONTINUE);
				packet_put_string(send_tok.value,
						  send_tok.length);
			}
			packet_send();
			packet_write_wait();

			
			/* If we've sent them data, they'd better be polite
			 * and reply. */
		
			type = packet_read();
			switch (type) {
			case SSH2_MSG_KEXGSS_HOSTKEY:
				debug("Received KEXGSS_HOSTKEY");
				serverhostkey=packet_get_string(&slen);
				break;
			case SSH2_MSG_KEXGSS_CONTINUE:
				debug("Received GSSAPI_CONTINUE");
				if (maj_status == GSS_S_COMPLETE) 
					fatal("GSSAPI Continue received from server when complete");
				recv_tok.value=packet_get_string(&recv_tok.length);
				break;
			case SSH2_MSG_KEXGSS_COMPLETE:
				debug("Received GSSAPI_COMPLETE");
			        packet_get_bignum2(dh_server_pub);
			    	msg_tok.value=
			    	    packet_get_string(&msg_tok.length);

				/* Is there a token included? */
				if (packet_get_char()) {
					recv_tok.value=
					    packet_get_string(&recv_tok.length);
					/* If we're already complete - protocol error */
					if (maj_status == GSS_S_COMPLETE)
						packet_disconnect("Protocol error: received token when complete");
				} else {
				   	/* No token included */
				   	if (maj_status != GSS_S_COMPLETE)
				   		packet_disconnect("Protocol error: did not receive final token");
				}
				break;
			case SSH2_MSG_KEXGSS_ERROR:
				debug("Received Error");
				maj_status=packet_get_int();
				min_status=packet_get_int();
				msg=packet_get_string(NULL);
				lang=packet_get_string(NULL);
				fprintf(stderr,"GSSAPI Error: \n%s",msg);
			default:
				packet_disconnect("Protocol error: didn't expect packet type %d",
		    		type);
			}
			token_ptr=&recv_tok;
		} else {
			/* No data, and not complete */
			if (maj_status!=GSS_S_COMPLETE) {
				fatal("Not complete, and no token output");
			}
		}
    	} while (maj_status & GSS_S_CONTINUE_NEEDED);
    	
    	/* We _must_ have received a COMPLETE message in reply from the 
    	 * server, which will have set dh_server_pub and msg_tok */
    	 
    	if (type!=SSH2_MSG_KEXGSS_COMPLETE)
    	   fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");
    	 	    	
	/* Check f in range [1, p-1] */
        if (!dh_pub_is_valid(dh, dh_server_pub))
                        packet_disconnect("bad server public DH value");
                        
        /* compute K=f^x mod p */
        klen = DH_size(dh);
        kbuf = xmalloc(klen);
        kout = DH_compute_key(kbuf, dh_server_pub, dh);
        
        shared_secret = BN_new();
        BN_bin2bn(kbuf,kout, shared_secret);
        memset(kbuf, 0, klen);
        xfree(kbuf);
        
        /* The GSS hash is identical to the DH one */
        hash = kex_dh_hash(
 	    kex->client_version_string,
            kex->server_version_string,
            buffer_ptr(&kex->my), buffer_len(&kex->my),
            buffer_ptr(&kex->peer), buffer_len(&kex->peer),
            serverhostkey, slen, /* server host key */
            dh->pub_key,	/* e */
            dh_server_pub,	/* f */
            shared_secret	/* K */
        );
        
        gssbuf.value=hash;
        gssbuf.length=20;
        
        /* Verify that H matches the token we just got. */
                if ((maj_status = gss_verify_mic(&min_status,
        	       		         ctxt->context,
        	                         &gssbuf,
        	                         &msg_tok,
        	                         NULL))) {

		packet_disconnect("Hash's MIC didn't verify");
      	}	
        
        DH_free(dh);
       	ssh_gssapi_delete_ctx(&ctxt);
        /* save session id */
        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);
        }
        
	kex_derive_keys(kex, hash, shared_secret);
	BN_clear_free(shared_secret);
        kex_finish(kex);
}

#endif /* GSSAPI */
Commit	Line	Data
73b00670	1	/*
3e196425	2	* Copyright (c) 2001-2003 Simon Wilkinson. All rights reserved.
73b00670	3	*
	4	* Redistribution and use in source and binary forms, with or without
	5	* modification, are permitted provided that the following conditions
	6	* are met:
	7	* 1. Redistributions of source code must retain the above copyright
	8	* notice, this list of conditions and the following disclaimer.
	9	* 2. Redistributions in binary form must reproduce the above copyright
	10	* notice, this list of conditions and the following disclaimer in the
	11	* documentation and/or other materials provided with the distribution.
	12	*
	13	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR `AS IS'' AND ANY EXPRESS OR
	14	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	15	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	16	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	17	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	18	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	19	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	20	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	21	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	22	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	23	*/
	24
	25	#include "includes.h"
	26
	27	#ifdef GSSAPI
	28
	29	#include <openssl/crypto.h>
	30	#include <openssl/bn.h>
	31
	32	#include "xmalloc.h"
	33	#include "buffer.h"
	34	#include "bufaux.h"
	35	#include "kex.h"
	36	#include "log.h"
	37	#include "packet.h"
	38	#include "dh.h"
	39	#include "ssh2.h"
	40	#include "ssh-gss.h"
	41
	42	void
	43	kexgss_client(Kex *kex)
	44	{
	45	gss_buffer_desc gssbuf,send_tok,recv_tok, msg_tok, *token_ptr;
	46	Gssctxt *ctxt;
	47	OM_uint32 maj_status, min_status, ret_flags;
	48	unsigned int klen, kout;
	49	DH *dh;
	50	BIGNUM *dh_server_pub = 0;
	51	BIGNUM *shared_secret = 0;
	52	unsigned char *kbuf;
	53	unsigned char *hash;
	54	unsigned char *serverhostkey;
	55	char *msg;
	56	char *lang;
	57	int type = 0;
	58	int first = 1;
	59	int slen = 0;
	60
	61	/* Initialise our GSSAPI world */
	62	ssh_gssapi_build_ctx(&ctxt);
	63	if (ssh_gssapi_client_id_kex(ctxt,kex->name)==NULL) {
	64	fatal("Couldn't identify host exchange");
	65	}
	66
67	if (ssh_gssapi_import_name(ctxt,kex->host)) {
68	fatal("Couldn't import hostname ");
69	}
70
71	/* This code should match that in ssh_dh1_client */
72
73	/* Step 1 - e is dh->pub_key */
74	dh = dh_new_group1();
75	dh_gen_key(dh, kex->we_need * 8);
76
77	/* This is f, we initialise it now to make life easier */
78	dh_server_pub = BN_new();
79	if (dh_server_pub == NULL) {
80	fatal("dh_server_pub == NULL");
81	}
82
83	token_ptr = GSS_C_NO_BUFFER;
3e196425	84
73b00670	85	do {
	86	debug("Calling gss_init_sec_context");
	87
	88	maj_status=ssh_gssapi_init_ctx(ctxt,
	89	kex->options.gss_deleg_creds,
	90	token_ptr,&send_tok,
	91	&ret_flags);
	92
	93	if (GSS_ERROR(maj_status)) {
3e196425	94	if (send_tok.length!=0) {
	95	/* Hmmm - not sure about this */
	96	packet_start(SSH2_MSG_KEXGSS_CONTINUE);
	97	packet_put_string(send_tok.value,
	98	send_tok.length);
	99	}
73b00670	100	fatal("gss_init_context failed");
3e196425	101	}
73b00670	102
	103	/* If we've got an old receive buffer get rid of it */
	104	if (token_ptr != GSS_C_NO_BUFFER)
	105	(void) gss_release_buffer(&min_status, &recv_tok);
	106
	107
	108	if (maj_status == GSS_S_COMPLETE) {
	109	/* If mutual state flag is not true, kex fails */
	110	if (!(ret_flags & GSS_C_MUTUAL_FLAG)) {
	111	fatal("Mutual authentication failed");
	112	}
	113	/* If integ avail flag is not true kex fails */
	114	if (!(ret_flags & GSS_C_INTEG_FLAG)) {
	115	fatal("Integrity check failed");
	116	}
	117	}
	118
	119	/* If we have data to send, then the last message that we
3e196425	120	* received cannot have been a 'complete'. */
73b00670	121	if (send_tok.length !=0) {
	122	if (first) {
	123	packet_start(SSH2_MSG_KEXGSS_INIT);
	124	packet_put_string(send_tok.value,
	125	send_tok.length);
	126	packet_put_bignum2(dh->pub_key);
	127	first=0;
	128	} else {
	129	packet_start(SSH2_MSG_KEXGSS_CONTINUE);
	130	packet_put_string(send_tok.value,
	131	send_tok.length);
	132	}
	133	packet_send();
	134	packet_write_wait();
	135
	136
	137	/* If we've sent them data, they'd better be polite
3e196425	138	* and reply. */
73b00670	139
	140	type = packet_read();
	141	switch (type) {
	142	case SSH2_MSG_KEXGSS_HOSTKEY:
	143	debug("Received KEXGSS_HOSTKEY");
	144	serverhostkey=packet_get_string(&slen);
	145	break;
	146	case SSH2_MSG_KEXGSS_CONTINUE:
	147	debug("Received GSSAPI_CONTINUE");
	148	if (maj_status == GSS_S_COMPLETE)
	149	fatal("GSSAPI Continue received from server when complete");
	150	recv_tok.value=packet_get_string(&recv_tok.length);
	151	break;
	152	case SSH2_MSG_KEXGSS_COMPLETE:
	153	debug("Received GSSAPI_COMPLETE");
	154	packet_get_bignum2(dh_server_pub);
	155	msg_tok.value=
	156	packet_get_string(&msg_tok.length);
	157
	158	/* Is there a token included? */
	159	if (packet_get_char()) {
	160	recv_tok.value=
	161	packet_get_string(&recv_tok.length);
	162	/* If we're already complete - protocol error */
	163	if (maj_status == GSS_S_COMPLETE)
	164	packet_disconnect("Protocol error: received token when complete");
	165	} else {
	166	/* No token included */
	167	if (maj_status != GSS_S_COMPLETE)
	168	packet_disconnect("Protocol error: did not receive final token");
	169	}
	170	break;
	171	case SSH2_MSG_KEXGSS_ERROR:
	172	debug("Received Error");
	173	maj_status=packet_get_int();
	174	min_status=packet_get_int();
	175	msg=packet_get_string(NULL);
	176	lang=packet_get_string(NULL);
3e196425	177	fprintf(stderr,"GSSAPI Error: \n%s",msg);
73b00670	178	default:
	179	packet_disconnect("Protocol error: didn't expect packet type %d",
	180	type);
	181	}
	182	token_ptr=&recv_tok;
3e196425	183	} else {
	184	/* No data, and not complete */
	185	if (maj_status!=GSS_S_COMPLETE) {
	186	fatal("Not complete, and no token output");
	187	}
73b00670	188	}
73b00670	189	} while (maj_status & GSS_S_CONTINUE_NEEDED);
	190
	191	/* We _must_ have received a COMPLETE message in reply from the
3e196425	192	* server, which will have set dh_server_pub and msg_tok */
3e196425	193
73b00670	194	if (type!=SSH2_MSG_KEXGSS_COMPLETE)
73b00670	195	fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");
3e196425	196
73b00670	197	/* Check f in range [1, p-1] */
	198	if (!dh_pub_is_valid(dh, dh_server_pub))
	199	packet_disconnect("bad server public DH value");
	200
	201	/* compute K=f^x mod p */
	202	klen = DH_size(dh);
	203	kbuf = xmalloc(klen);
	204	kout = DH_compute_key(kbuf, dh_server_pub, dh);
	205
	206	shared_secret = BN_new();
	207	BN_bin2bn(kbuf,kout, shared_secret);
	208	memset(kbuf, 0, klen);
	209	xfree(kbuf);
	210
	211	/* The GSS hash is identical to the DH one */
	212	hash = kex_dh_hash(
	213	kex->client_version_string,
	214	kex->server_version_string,
	215	buffer_ptr(&kex->my), buffer_len(&kex->my),
	216	buffer_ptr(&kex->peer), buffer_len(&kex->peer),
	217	serverhostkey, slen, /* server host key */
	218	dh->pub_key, /* e */
	219	dh_server_pub, /* f */
	220	shared_secret /* K */
	221	);
	222
	223	gssbuf.value=hash;
	224	gssbuf.length=20;
	225
	226	/* Verify that H matches the token we just got. */
	227	if ((maj_status = gss_verify_mic(&min_status,
	228	ctxt->context,
	229	&gssbuf,
	230	&msg_tok,
	231	NULL))) {
	232
	233	packet_disconnect("Hash's MIC didn't verify");
	234	}
	235
	236	DH_free(dh);
	237	ssh_gssapi_delete_ctx(&ctxt);
	238	/* save session id */
	239	if (kex->session_id == NULL) {
	240	kex->session_id_len = 20;
	241	kex->session_id = xmalloc(kex->session_id_len);
	242	memcpy(kex->session_id, hash, kex->session_id_len);
	243	}
	244
	245	kex_derive_keys(kex, hash, shared_secret);
	246	BN_clear_free(shared_secret);
	247	kex_finish(kex);
	248	}
	249
	250	#endif /* GSSAPI */