2 * Copyright (c) 2001,2002 Simon Wilkinson. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
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.
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.
29 #include <openssl/crypto.h>
30 #include <openssl/bn.h>
41 #include "monitor_wrap.h"
43 /* This is now the same as the DH hash ... */
47 char *client_version_string,
48 char *server_version_string,
49 char *ckexinit, int ckexinitlen,
50 char *skexinit, int skexinitlen,
51 u_char *serverhostkeyblob, int sbloblen,
52 BIGNUM *client_dh_pub,
53 BIGNUM *server_dh_pub,
54 BIGNUM *shared_secret)
57 static u_char digest[EVP_MAX_MD_SIZE];
58 EVP_MD *evp_md = EVP_sha1();
62 buffer_put_string(&b, client_version_string, strlen(client_version_string));
63 buffer_put_string(&b, server_version_string, strlen(server_version_string));
65 /* kexinit messages: fake header: len+SSH2_MSG_KEXINIT */
66 buffer_put_int(&b, ckexinitlen+1);
67 buffer_put_char(&b, SSH2_MSG_KEXINIT);
68 buffer_append(&b, ckexinit, ckexinitlen);
69 buffer_put_int(&b, skexinitlen+1);
70 buffer_put_char(&b, SSH2_MSG_KEXINIT);
71 buffer_append(&b, skexinit, skexinitlen);
73 buffer_put_string(&b, serverhostkeyblob, sbloblen);
74 buffer_put_bignum2(&b, client_dh_pub);
75 buffer_put_bignum2(&b, server_dh_pub);
76 buffer_put_bignum2(&b, shared_secret);
81 EVP_DigestInit(&md, evp_md);
82 EVP_DigestUpdate(&md, buffer_ptr(&b), buffer_len(&b));
83 EVP_DigestFinal(&md, digest, NULL);
88 dump_digest("hash", digest, evp_md->md_size);
94 kexgss_client(Kex *kex)
96 gss_buffer_desc gssbuf,send_tok,recv_tok, msg_tok, *token_ptr;
98 OM_uint32 maj_status, min_status, ret_flags;
99 unsigned int klen, kout;
101 BIGNUM *dh_server_pub = 0;
102 BIGNUM *shared_secret = 0;
105 unsigned char *serverhostkey;
110 /* Initialise our GSSAPI world */
111 ssh_gssapi_build_ctx(&ctxt);
112 if (ssh_gssapi_id_kex(ctxt,kex->name)==NULL) {
113 fatal("Couldn't identify host exchange");
115 if (ssh_gssapi_import_name(ctxt,kex->host)) {
116 fatal("Couldn't import hostname ");
119 /* This code should match that in ssh_dh1_client */
121 /* Step 1 - e is dh->pub_key */
122 dh = dh_new_group1();
123 dh_gen_key(dh, kex->we_need * 8);
125 /* This is f, we initialise it now to make life easier */
126 dh_server_pub = BN_new();
127 if (dh_server_pub == NULL) {
128 fatal("dh_server_pub == NULL");
131 token_ptr = GSS_C_NO_BUFFER;
134 debug("Calling gss_init_sec_context");
136 maj_status=ssh_gssapi_init_ctx(ctxt,
137 kex->options.gss_deleg_creds,
141 if (GSS_ERROR(maj_status)) {
142 fatal("gss_init_context failed");
145 /* If we've got an old receive buffer get rid of it */
146 if (token_ptr != GSS_C_NO_BUFFER)
147 (void) gss_release_buffer(&min_status, &recv_tok);
150 if (maj_status == GSS_S_COMPLETE) {
151 /* If mutual state flag is not true, kex fails */
152 if (!(ret_flags & GSS_C_MUTUAL_FLAG)) {
153 fatal("Mutual authentication failed");
155 /* If integ avail flag is not true kex fails */
156 if (!(ret_flags & GSS_C_INTEG_FLAG)) {
157 fatal("Integrity check failed");
161 /* If we have data to send, then the last message that we
162 * received cannot have been a 'complete'. */
163 if (send_tok.length !=0) {
165 packet_start(SSH2_MSG_KEXGSS_INIT);
166 packet_put_string(send_tok.value,
168 packet_put_bignum2(dh->pub_key);
171 packet_start(SSH2_MSG_KEXGSS_CONTINUE);
172 packet_put_string(send_tok.value,
179 /* If we've sent them data, they'd better be polite
182 type = packet_read();
184 case SSH2_MSG_KEXGSS_HOSTKEY:
185 debug("Received KEXGSS_HOSTKEY");
186 serverhostkey=packet_get_string(&slen);
188 case SSH2_MSG_KEXGSS_CONTINUE:
189 debug("Received GSSAPI_CONTINUE");
190 if (maj_status == GSS_S_COMPLETE)
191 fatal("GSSAPI Continue received from server when complete");
192 recv_tok.value=packet_get_string(&slen);
193 recv_tok.length=slen; /* int vs. size_t */
195 case SSH2_MSG_KEXGSS_COMPLETE:
196 debug("Received GSSAPI_COMPLETE");
197 packet_get_bignum2(dh_server_pub);
198 msg_tok.value=packet_get_string(&slen);
199 msg_tok.length=slen; /* int vs. size_t */
201 /* Is there a token included? */
202 if (packet_get_char()) {
204 packet_get_string(&slen);
205 recv_tok.length=slen; /* int/size_t */
206 /* If we're already complete - protocol error */
207 if (maj_status == GSS_S_COMPLETE)
208 packet_disconnect("Protocol error: received token when complete");
210 /* No token included */
211 if (maj_status != GSS_S_COMPLETE)
212 packet_disconnect("Protocol error: did not receive final token");
216 packet_disconnect("Protocol error: didn't expect packet type %d",
222 } while (maj_status & GSS_S_CONTINUE_NEEDED);
224 /* We _must_ have received a COMPLETE message in reply from the
225 * server, which will have set dh_server_pub and msg_tok */
227 if (type!=SSH2_MSG_KEXGSS_COMPLETE)
228 fatal("Didn't receive a SSH2_MSG_KEXGSS_COMPLETE when I expected it");
230 /* Check f in range [1, p-1] */
231 if (!dh_pub_is_valid(dh, dh_server_pub))
232 packet_disconnect("bad server public DH value");
234 /* compute K=f^x mod p */
236 kbuf = xmalloc(klen);
237 kout = DH_compute_key(kbuf, dh_server_pub, dh);
239 shared_secret = BN_new();
240 BN_bin2bn(kbuf,kout, shared_secret);
241 memset(kbuf, 0, klen);
245 hash = kex_gssapi_hash(
246 kex->client_version_string,
247 kex->server_version_string,
248 buffer_ptr(&kex->my), buffer_len(&kex->my),
249 buffer_ptr(&kex->peer), buffer_len(&kex->peer),
250 serverhostkey, slen, /* server host key */
252 dh_server_pub, /* f */
253 shared_secret /* K */
259 /* Verify that H matches the token we just got. */
260 if ((maj_status = gss_verify_mic(&min_status,
266 packet_disconnect("Hash's MIC didn't verify");
270 ssh_gssapi_delete_ctx(&ctxt);
271 /* save session id */
272 if (kex->session_id == NULL) {
273 kex->session_id_len = 20;
274 kex->session_id = xmalloc(kex->session_id_len);
275 memcpy(kex->session_id, hash, kex->session_id_len);
278 kex_derive_keys(kex, hash, shared_secret);
279 BN_clear_free(shared_secret);
287 kexgss_server(Kex *kex)
290 OM_uint32 maj_status, min_status;
292 /* Some GSSAPI implementations use the input value of ret_flags (an
293 * output variable) as a means of triggering mechanism specific
294 * features. Initializing it to zero avoids inadvertently
295 * activating this non-standard behaviour.*/
297 OM_uint32 ret_flags = 0;
298 gss_buffer_desc gssbuf,send_tok,recv_tok,msg_tok;
299 Gssctxt *ctxt = NULL;
300 unsigned int klen, kout;
304 BIGNUM *shared_secret = NULL;
305 BIGNUM *dh_client_pub = NULL;
310 /* Initialise GSSAPI */
312 debug2("%s: Identifying %s",__func__,kex->name);
313 oid=ssh_gssapi_id_kex(ctxt,kex->name);
315 packet_disconnect("Unknown gssapi mechanism");
318 debug2("%s: Acquiring credentials",__func__);
320 if (GSS_ERROR(PRIVSEP(ssh_gssapi_server_ctx(&ctxt,oid))))
321 packet_disconnect("Unable to acquire credentials for the server");
324 debug("Wait SSH2_MSG_GSSAPI_INIT");
325 type = packet_read();
327 case SSH2_MSG_KEXGSS_INIT:
328 if (dh_client_pub!=NULL)
329 packet_disconnect("Received KEXGSS_INIT after initialising");
330 recv_tok.value=packet_get_string(&slen);
331 recv_tok.length=slen; /* int vs. size_t */
333 dh_client_pub = BN_new();
335 if (dh_client_pub == NULL)
336 fatal("dh_client_pub == NULL");
337 packet_get_bignum2(dh_client_pub);
339 /* Send SSH_MSG_KEXGSS_HOSTKEY here, if we want */
341 case SSH2_MSG_KEXGSS_CONTINUE:
342 if (dh_client_pub == NULL)
343 packet_disconnect("Received KEXGSS_CONTINUE without initialising");
344 recv_tok.value=packet_get_string(&slen);
345 recv_tok.length=slen; /* int vs. size_t */
348 packet_disconnect("Protocol error: didn't expect packet type %d",
352 maj_status=PRIVSEP(ssh_gssapi_accept_ctx(ctxt,&recv_tok,
353 &send_tok, &ret_flags));
355 gss_release_buffer(&min_status,&recv_tok);
357 #ifdef GSS_C_GLOBUS_LIMITED_PROXY_FLAG
358 if (ret_flags & GSS_C_GLOBUS_LIMITED_PROXY_FLAG) {
359 packet_disconnect("Limited proxy is not allowed in gssapi key exchange.");
363 if (maj_status & GSS_S_CONTINUE_NEEDED) {
364 debug("Sending GSSAPI_CONTINUE");
365 packet_start(SSH2_MSG_KEXGSS_CONTINUE);
366 packet_put_string(send_tok.value,send_tok.length);
369 gss_release_buffer(&min_status, &send_tok);
371 } while (maj_status & GSS_S_CONTINUE_NEEDED);
373 if (GSS_ERROR(maj_status)) {
374 ssh_gssapi_send_error(maj_status,min_status);
375 packet_disconnect("gssapi key exchange handshake failed");
378 debug("gss_complete");
379 if (!(ret_flags & GSS_C_MUTUAL_FLAG)) {
380 ssh_gssapi_send_error(maj_status,min_status);
381 packet_disconnect("gssapi mutual authentication failed");
384 if (!(ret_flags & GSS_C_INTEG_FLAG)) {
385 ssh_gssapi_send_error(maj_status,min_status);
386 packet_disconnect("gssapi channel integrity not established");
389 dh = dh_new_group1();
390 dh_gen_key(dh, kex->we_need * 8);
392 if (!dh_pub_is_valid(dh, dh_client_pub))
393 packet_disconnect("bad client public DH value");
396 kbuf = xmalloc(klen);
397 kout = DH_compute_key(kbuf, dh_client_pub, dh);
399 shared_secret = BN_new();
400 BN_bin2bn(kbuf, kout, shared_secret);
401 memset(kbuf, 0, klen);
404 hash = kex_gssapi_hash(
405 kex->client_version_string,
406 kex->server_version_string,
407 buffer_ptr(&kex->peer), buffer_len(&kex->peer),
408 buffer_ptr(&kex->my), buffer_len(&kex->my),
409 NULL, 0, /* Change this if we start sending host keys */
414 BN_free(dh_client_pub);
416 if (kex->session_id == NULL) {
417 kex->session_id_len = 20;
418 kex->session_id = xmalloc(kex->session_id_len);
419 memcpy(kex->session_id, hash, kex->session_id_len);
423 gssbuf.length = 20; /* Hashlen appears to always be 20 */
425 if (GSS_ERROR(PRIVSEP(ssh_gssapi_sign(ctxt,&gssbuf,&msg_tok)))) {
426 ssh_gssapi_send_error(maj_status,min_status);
427 packet_disconnect("Couldn't get MIC");
430 packet_start(SSH2_MSG_KEXGSS_COMPLETE);
431 packet_put_bignum2(dh->pub_key);
432 packet_put_string((char *)msg_tok.value,msg_tok.length);
434 if (send_tok.length!=0) {
435 packet_put_char(1); /* true */
436 packet_put_string((char *)send_tok.value,send_tok.length);
438 packet_put_char(0); /* false */
443 /* We used to store the client name and credentials here for later
444 * use. With privsep, its easier to do this as a by product of the
445 * call to accept_context, which stores delegated information when
446 * the context is complete */
448 gss_release_buffer(&min_status, &send_tok);
450 /* If we've got a context, delete it. It may be NULL if we've been
452 ssh_gssapi_delete_ctx(&ctxt);
456 kex_derive_keys(kex, hash, shared_secret);
457 BN_clear_free(shared_secret);