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

/*
 * Copyright (c) 2001,2002 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 "canohost.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, strlen;
	
	/* 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,get_canonical_hostname(1))) {
		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)) {
			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(&strlen);
				recv_tok.length=strlen; /* int vs. size_t */
				break;
			case SSH2_MSG_KEXGSS_COMPLETE:
				debug("Received GSSAPI_COMPLETE");
			        packet_get_bignum2(dh_server_pub);
			    	msg_tok.value=packet_get_string(&strlen);
				msg_tok.length=strlen; /* int vs. size_t */

				/* Is there a token included? */
				if (packet_get_char()) {
					recv_tok.value=
					    packet_get_string(&strlen);
					recv_tok.length=strlen; /*int/size_t*/
					/* 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);
				fatal(msg);
			default:
				packet_disconnect("Protocol error: didn't expect packet type %d",
		    		type);
			}
			token_ptr=&recv_tok;
		}

    	} 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
b46fa825	1	/*
	2	* Copyright (c) 2001,2002 Simon Wilkinson. All rights reserved.
	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"
b46fa825	41	#include "canohost.h"
	42
	43
	44	void
	45	kexgss_client(Kex *kex)
	46	{
	47	gss_buffer_desc gssbuf,send_tok,recv_tok, msg_tok, *token_ptr;
	48	Gssctxt *ctxt;
	49	OM_uint32 maj_status, min_status, ret_flags;
	50	unsigned int klen, kout;
	51	DH *dh;
	52	BIGNUM *dh_server_pub = 0;
	53	BIGNUM *shared_secret = 0;
	54	unsigned char *kbuf;
	55	unsigned char *hash;
	56	unsigned char *serverhostkey;
23987cb8	57	char *msg;
23987cb8	58	char *lang;
b46fa825	59	int type = 0;
b46fa825	60	int first = 1;
23987cb8	61	int slen = 0, strlen;
b46fa825	62
	63	/* Initialise our GSSAPI world */
	64	ssh_gssapi_build_ctx(&ctxt);
23987cb8	65	if (ssh_gssapi_client_id_kex(ctxt,kex->name)==NULL) {
b46fa825	66	fatal("Couldn't identify host exchange");
	67	}
	68	if (ssh_gssapi_import_name(ctxt,get_canonical_hostname(1))) {
	69	fatal("Couldn't import hostname ");
	70	}
	71
	72	/* This code should match that in ssh_dh1_client */
	73
	74	/* Step 1 - e is dh->pub_key */
	75	dh = dh_new_group1();
	76	dh_gen_key(dh, kex->we_need * 8);
	77
	78	/* This is f, we initialise it now to make life easier */
	79	dh_server_pub = BN_new();
	80	if (dh_server_pub == NULL) {
	81	fatal("dh_server_pub == NULL");
	82	}
	83
	84	token_ptr = GSS_C_NO_BUFFER;
23987cb8	85
b46fa825	86	do {
	87	debug("Calling gss_init_sec_context");
	88
	89	maj_status=ssh_gssapi_init_ctx(ctxt,
	90	kex->options.gss_deleg_creds,
	91	token_ptr,&send_tok,
	92	&ret_flags);
	93
	94	if (GSS_ERROR(maj_status)) {
	95	fatal("gss_init_context failed");
	96	}
	97
	98	/* If we've got an old receive buffer get rid of it */
	99	if (token_ptr != GSS_C_NO_BUFFER)
	100	(void) gss_release_buffer(&min_status, &recv_tok);
	101
	102
	103	if (maj_status == GSS_S_COMPLETE) {
	104	/* If mutual state flag is not true, kex fails */
	105	if (!(ret_flags & GSS_C_MUTUAL_FLAG)) {
	106	fatal("Mutual authentication failed");
	107	}
	108	/* If integ avail flag is not true kex fails */
	109	if (!(ret_flags & GSS_C_INTEG_FLAG)) {
	110	fatal("Integrity check failed");
	111	}
	112	}
	113
	114	/* If we have data to send, then the last message that we
	115	* received cannot have been a 'complete'. */
	116	if (send_tok.length !=0) {
	117	if (first) {
	118	packet_start(SSH2_MSG_KEXGSS_INIT);
	119	packet_put_string(send_tok.value,
	120	send_tok.length);
	121	packet_put_bignum2(dh->pub_key);
	122	first=0;
	123	} else {
	124	packet_start(SSH2_MSG_KEXGSS_CONTINUE);
	125	packet_put_string(send_tok.value,
	126	send_tok.length);
	127	}
	128	packet_send();
	129	packet_write_wait();
	130
	131
	132	/* If we've sent them data, they'd better be polite
	133	* and reply. */
	134
	135	type = packet_read();
	136	switch (type) {
	137	case SSH2_MSG_KEXGSS_HOSTKEY:
	138	debug("Received KEXGSS_HOSTKEY");
	139	serverhostkey=packet_get_string(&slen);
	140	break;
	141	case SSH2_MSG_KEXGSS_CONTINUE:
	142	debug("Received GSSAPI_CONTINUE");
	143	if (maj_status == GSS_S_COMPLETE)
	144	fatal("GSSAPI Continue received from server when complete");
23987cb8	145	recv_tok.value=packet_get_string(&strlen);
23987cb8	146	recv_tok.length=strlen; /* int vs. size_t */
b46fa825	147	break;
	148	case SSH2_MSG_KEXGSS_COMPLETE:
	149	debug("Received GSSAPI_COMPLETE");
	150	packet_get_bignum2(dh_server_pub);
23987cb8	151	msg_tok.value=packet_get_string(&strlen);
23987cb8	152	msg_tok.length=strlen; /* int vs. size_t */
b46fa825	153
	154	/* Is there a token included? */
	155	if (packet_get_char()) {
	156	recv_tok.value=
23987cb8	157	packet_get_string(&strlen);
23987cb8	158	recv_tok.length=strlen; /int/size_t/
b46fa825	159	/* If we're already complete - protocol error */
	160	if (maj_status == GSS_S_COMPLETE)
	161	packet_disconnect("Protocol error: received token when complete");
	162	} else {
	163	/* No token included */
	164	if (maj_status != GSS_S_COMPLETE)
	165	packet_disconnect("Protocol error: did not receive final token");
	166	}
	167	break;
23987cb8	168	case SSH2_MSG_KEXGSS_ERROR:
	169	debug("Received Error");
	170	maj_status=packet_get_int();
	171	min_status=packet_get_int();
	172	msg=packet_get_string(NULL);
	173	lang=packet_get_string(NULL);
	174	fatal(msg);
b46fa825	175	default:
	176	packet_disconnect("Protocol error: didn't expect packet type %d",
	177	type);
	178	}
	179	token_ptr=&recv_tok;
	180	}
	181
	182	} while (maj_status & GSS_S_CONTINUE_NEEDED);
	183
	184	/* We _must_ have received a COMPLETE message in reply from the
	185	* server, which will have set dh_server_pub and msg_tok */
	186
	187	if (type!=SSH2_MSG_KEXGSS_COMPLETE)
	188	fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");
	189
	190	/* Check f in range [1, p-1] */
	191	if (!dh_pub_is_valid(dh, dh_server_pub))
	192	packet_disconnect("bad server public DH value");
	193
	194	/* compute K=f^x mod p */
	195	klen = DH_size(dh);
	196	kbuf = xmalloc(klen);
	197	kout = DH_compute_key(kbuf, dh_server_pub, dh);
	198
	199	shared_secret = BN_new();
	200	BN_bin2bn(kbuf,kout, shared_secret);
	201	memset(kbuf, 0, klen);
	202	xfree(kbuf);
	203
23987cb8	204	/* The GSS hash is identical to the DH one */
23987cb8	205	hash = kex_dh_hash(
b46fa825	206	kex->client_version_string,
	207	kex->server_version_string,
	208	buffer_ptr(&kex->my), buffer_len(&kex->my),
	209	buffer_ptr(&kex->peer), buffer_len(&kex->peer),
	210	serverhostkey, slen, /* server host key */
	211	dh->pub_key, /* e */
	212	dh_server_pub, /* f */
	213	shared_secret /* K */
	214	);
	215
	216	gssbuf.value=hash;
	217	gssbuf.length=20;
	218
	219	/* Verify that H matches the token we just got. */
	220	if ((maj_status = gss_verify_mic(&min_status,
	221	ctxt->context,
	222	&gssbuf,
	223	&msg_tok,
	224	NULL))) {
	225
	226	packet_disconnect("Hash's MIC didn't verify");
	227	}
	228
	229	DH_free(dh);
	230	ssh_gssapi_delete_ctx(&ctxt);
	231	/* save session id */
	232	if (kex->session_id == NULL) {
	233	kex->session_id_len = 20;
	234	kex->session_id = xmalloc(kex->session_id_len);
	235	memcpy(kex->session_id, hash, kex->session_id_len);
	236	}
	237
	238	kex_derive_keys(kex, hash, shared_secret);
	239	BN_clear_free(shared_secret);
	240	kex_finish(kex);
	241	}
	242
	243	#endif /* GSSAPI */