[gssapi-openssh.git] / openssh / kexgsss.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 "monitor_wrap.h"
#include "canohost.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,send_tok,recv_tok,msg_tok;
	Gssctxt *ctxt = NULL;
        unsigned int klen, kout;
        unsigned char *kbuf;
        unsigned char *hash;
        DH *dh;
        BIGNUM *shared_secret = NULL;
        BIGNUM *dh_client_pub = NULL;
	int type =0;
	gss_OID oid;
	u_int slen;
	
	/* Initialise GSSAPI */

	debug2("%s: Identifying %s",__func__,kex->name);
	oid=ssh_gssapi_id_kex(ctxt,kex->name);
	if (oid==NULL) {
	   packet_disconnect("Unknown gssapi mechanism");
	}
	
	debug2("%s: Acquiring credentials",__func__);
	
	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt,oid))))
	   packet_disconnect("Unable to acquire credentials for the server");

	do {
		debug("Wait SSH2_MSG_GSSAPI_INIT");
		type = packet_read();
		switch(type) {
		case SSH2_MSG_KEXGSS_INIT:
			if (dh_client_pub!=NULL) 
				packet_disconnect("Received KEXGSS_INIT after initialising");
			recv_tok.value=packet_get_string(&slen);
			recv_tok.length=slen; /* int vs. size_t */

		        dh_client_pub = BN_new();
		        
		        if (dh_client_pub == 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:
			if (dh_client_pub == NULL)
				packet_disconnect("Received KEXGSS_CONTINUE without initialising");
			recv_tok.value=packet_get_string(&slen);
			recv_tok.length=slen; /* int vs. size_t */
			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));

		gss_release_buffer(&min_status,&recv_tok);

#ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG
                if (ret_flags & GSS_C_GLOBUS_LIMITED_PROXY_FLAG) {
                        packet_disconnect("Limited proxy is not allowed in gssapi key exchange.");
                }
#endif
		
		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();
			packet_write_wait();
			gss_release_buffer(&min_status, &send_tok);
		}
	} while (maj_status & GSS_S_CONTINUE_NEEDED);

	if (GSS_ERROR(maj_status)) {
		ssh_gssapi_send_error(oid,maj_status,min_status);
		packet_disconnect("gssapi key exchange handshake failed");
	}

	debug("gss_complete");
	if (!(ret_flags & GSS_C_MUTUAL_FLAG)) {
		ssh_gssapi_send_error(oid,maj_status,min_status);
		packet_disconnect("gssapi mutual authentication failed");
	}
		
	if (!(ret_flags & GSS_C_INTEG_FLAG)) {
		ssh_gssapi_send_error(oid,maj_status,min_status);
		packet_disconnect("gssapi channel integrity not established");
	}		
	
	dh = dh_new_group1();
	dh_gen_key(dh, kex->we_need * 8);
	
        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);
	
        hash = kex_gssapi_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)))) {
		if (ctxt) { /* may be NULL under privsep */
		    ssh_gssapi_send_error(ctxt->oid,maj_status,min_status);
		} else {
		    ssh_gssapi_send_error(GSS_C_NO_OID,maj_status,min_status);
		}
		packet_disconnect("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();
	packet_write_wait();

        /* We used to store the client name and credentials here for later
         * use. With privsep, its easier to do this as a by product of the
         * call to accept_context, which stores delegated information when
         * the context is complete */
         
	gss_release_buffer(&min_status, &send_tok);	

	/* If we've got a context, delete it. It may be NULL if we've been
	 * using privsep */
	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 */
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"
	41	#include "monitor_wrap.h"
	42	#include "canohost.h"
	43
	44	void
	45	kexgss_server(Kex *kex)
	46	{
	47
	48	OM_uint32 maj_status, min_status;
	49
	50	/* Some GSSAPI implementations use the input value of ret_flags (an
	51	* output variable) as a means of triggering mechanism specific
	52	* features. Initializing it to zero avoids inadvertently
	53	* activating this non-standard behaviour.*/
	54
	55	OM_uint32 ret_flags = 0;
	56	gss_buffer_desc gssbuf,send_tok,recv_tok,msg_tok;
	57	Gssctxt *ctxt = NULL;
	58	unsigned int klen, kout;
	59	unsigned char *kbuf;
	60	unsigned char *hash;
	61	DH *dh;
	62	BIGNUM *shared_secret = NULL;
	63	BIGNUM *dh_client_pub = NULL;
	64	int type =0;
65	gss_OID oid;
66	u_int slen;
67
68	/* Initialise GSSAPI */
69
70	debug2("%s: Identifying %s",__func__,kex->name);
71	oid=ssh_gssapi_id_kex(ctxt,kex->name);
72	if (oid==NULL) {
73	packet_disconnect("Unknown gssapi mechanism");
74	}
75
76	debug2("%s: Acquiring credentials",__func__);
77
78	if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt,oid))))
79	packet_disconnect("Unable to acquire credentials for the server");
80
81	do {
82	debug("Wait SSH2_MSG_GSSAPI_INIT");
83	type = packet_read();
84	switch(type) {
85	case SSH2_MSG_KEXGSS_INIT:
86	if (dh_client_pub!=NULL)
87	packet_disconnect("Received KEXGSS_INIT after initialising");
88	recv_tok.value=packet_get_string(&slen);
89	recv_tok.length=slen; /* int vs. size_t */
90
91	dh_client_pub = BN_new();
92
93	if (dh_client_pub == NULL)
94	fatal("dh_client_pub == NULL");
95	packet_get_bignum2(dh_client_pub);
96
97	/* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
98	break;
99	case SSH2_MSG_KEXGSS_CONTINUE:
100	if (dh_client_pub == NULL)
101	packet_disconnect("Received KEXGSS_CONTINUE without initialising");
102	recv_tok.value=packet_get_string(&slen);
103	recv_tok.length=slen; /* int vs. size_t */
104	break;
105	default:
106	packet_disconnect("Protocol error: didn't expect packet type %d",
107	type);
108	}
109
110	maj_status=PRIVSEP(ssh_gssapi_accept_ctx(ctxt,&recv_tok,
111	&send_tok, &ret_flags));
112
113	gss_release_buffer(&min_status,&recv_tok);
114
115	#ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG
116	if (ret_flags & GSS_C_GLOBUS_LIMITED_PROXY_FLAG) {
117	packet_disconnect("Limited proxy is not allowed in gssapi key exchange.");
118	}
119	#endif
120
121	if (maj_status & GSS_S_CONTINUE_NEEDED) {
122	debug("Sending GSSAPI_CONTINUE");
123	packet_start(SSH2_MSG_KEXGSS_CONTINUE);
124	packet_put_string(send_tok.value,send_tok.length);
125	packet_send();
126	packet_write_wait();
127	gss_release_buffer(&min_status, &send_tok);
128	}
129	} while (maj_status & GSS_S_CONTINUE_NEEDED);
130
131	if (GSS_ERROR(maj_status)) {
132	ssh_gssapi_send_error(oid,maj_status,min_status);
133	packet_disconnect("gssapi key exchange handshake failed");
134	}
135
136	debug("gss_complete");
137	if (!(ret_flags & GSS_C_MUTUAL_FLAG)) {
138	ssh_gssapi_send_error(oid,maj_status,min_status);
139	packet_disconnect("gssapi mutual authentication failed");
140	}
141
142	if (!(ret_flags & GSS_C_INTEG_FLAG)) {
143	ssh_gssapi_send_error(oid,maj_status,min_status);
144	packet_disconnect("gssapi channel integrity not established");
145	}
146
147	dh = dh_new_group1();
148	dh_gen_key(dh, kex->we_need * 8);
149
150	if (!dh_pub_is_valid(dh, dh_client_pub))
151	packet_disconnect("bad client public DH value");
152
153	klen = DH_size(dh);
154	kbuf = xmalloc(klen);
155	kout = DH_compute_key(kbuf, dh_client_pub, dh);
156
157	shared_secret = BN_new();
158	BN_bin2bn(kbuf, kout, shared_secret);
159	memset(kbuf, 0, klen);
160	xfree(kbuf);
161
162	hash = kex_gssapi_hash(
163	kex->client_version_string,
164	kex->server_version_string,
165	buffer_ptr(&kex->peer), buffer_len(&kex->peer),
166	buffer_ptr(&kex->my), buffer_len(&kex->my),
167	NULL, 0, /* Change this if we start sending host keys */
168	dh_client_pub,
169	dh->pub_key,
170	shared_secret
171	);
172	BN_free(dh_client_pub);
173
174	if (kex->session_id == NULL) {
175	kex->session_id_len = 20;
176	kex->session_id = xmalloc(kex->session_id_len);
177	memcpy(kex->session_id, hash, kex->session_id_len);
178	}
179
180	gssbuf.value = hash;
181	gssbuf.length = 20; /* Hashlen appears to always be 20 */
182
183	if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt,&gssbuf,&msg_tok)))) {
184	if (ctxt) { /* may be NULL under privsep */
185	ssh_gssapi_send_error(ctxt->oid,maj_status,min_status);
186	} else {
187	ssh_gssapi_send_error(GSS_C_NO_OID,maj_status,min_status);
188	}
189	packet_disconnect("Couldn't get MIC");
190	}
191
192	packet_start(SSH2_MSG_KEXGSS_COMPLETE);
193	packet_put_bignum2(dh->pub_key);
194	packet_put_string((char *)msg_tok.value,msg_tok.length);
195
196	if (send_tok.length!=0) {
197	packet_put_char(1); /* true */
198	packet_put_string((char *)send_tok.value,send_tok.length);
199	} else {
200	packet_put_char(0); /* false */
201	}
202	packet_send();
203	packet_write_wait();
204
205	/* We used to store the client name and credentials here for later
206	* use. With privsep, its easier to do this as a by product of the
207	* call to accept_context, which stores delegated information when
208	* the context is complete */
209
210	gss_release_buffer(&min_status, &send_tok);
211
212	/* If we've got a context, delete it. It may be NULL if we've been
213	* using privsep */
214	ssh_gssapi_delete_ctx(&ctxt);
215
216	DH_free(dh);
217
218	kex_derive_keys(kex, hash, shared_secret);
219	BN_clear_free(shared_secret);
220	kex_finish(kex);
221	}
222
223	#endif /* GSSAPI */