xref: /freebsd/crypto/openssh/sshconnect2.c (revision 195ebc7e9e4b129de810833791a19dfb4349d6a9)
1 /* $OpenBSD: sshconnect2.c,v 1.170 2008/11/04 08:22:13 djm Exp $ */
2 /*
3  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
4  * Copyright (c) 2008 Damien Miller.  All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 #include "includes.h"
28 
29 #include <sys/types.h>
30 #include <sys/socket.h>
31 #include <sys/wait.h>
32 #include <sys/stat.h>
33 
34 #include <errno.h>
35 #include <netdb.h>
36 #include <pwd.h>
37 #include <signal.h>
38 #include <stdarg.h>
39 #include <stdio.h>
40 #include <string.h>
41 #include <unistd.h>
42 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H)
43 #include <vis.h>
44 #endif
45 
46 #include "openbsd-compat/sys-queue.h"
47 
48 #include "xmalloc.h"
49 #include "ssh.h"
50 #include "ssh2.h"
51 #include "buffer.h"
52 #include "packet.h"
53 #include "compat.h"
54 #include "cipher.h"
55 #include "key.h"
56 #include "kex.h"
57 #include "myproposal.h"
58 #include "sshconnect.h"
59 #include "authfile.h"
60 #include "dh.h"
61 #include "authfd.h"
62 #include "log.h"
63 #include "readconf.h"
64 #include "misc.h"
65 #include "match.h"
66 #include "dispatch.h"
67 #include "canohost.h"
68 #include "msg.h"
69 #include "pathnames.h"
70 #include "uidswap.h"
71 #include "jpake.h"
72 
73 #ifdef GSSAPI
74 #include "ssh-gss.h"
75 #endif
76 
77 /* import */
78 extern char *client_version_string;
79 extern char *server_version_string;
80 extern Options options;
81 
82 /*
83  * SSH2 key exchange
84  */
85 
86 u_char *session_id2 = NULL;
87 u_int session_id2_len = 0;
88 
89 char *xxx_host;
90 struct sockaddr *xxx_hostaddr;
91 
92 Kex *xxx_kex = NULL;
93 
94 static int
95 verify_host_key_callback(Key *hostkey)
96 {
97 	if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
98 		fatal("Host key verification failed.");
99 	return 0;
100 }
101 
102 void
103 ssh_kex2(char *host, struct sockaddr *hostaddr)
104 {
105 	Kex *kex;
106 
107 	xxx_host = host;
108 	xxx_hostaddr = hostaddr;
109 
110 	if (options.ciphers == (char *)-1) {
111 		logit("No valid ciphers for protocol version 2 given, using defaults.");
112 		options.ciphers = NULL;
113 	}
114 	if (options.ciphers != NULL) {
115 		myproposal[PROPOSAL_ENC_ALGS_CTOS] =
116 		myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
117 	}
118 	myproposal[PROPOSAL_ENC_ALGS_CTOS] =
119 	    compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
120 	myproposal[PROPOSAL_ENC_ALGS_STOC] =
121 	    compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
122 	if (options.compression) {
123 		myproposal[PROPOSAL_COMP_ALGS_CTOS] =
124 		myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
125 	} else {
126 		myproposal[PROPOSAL_COMP_ALGS_CTOS] =
127 		myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
128 	}
129 	if (options.macs != NULL) {
130 		myproposal[PROPOSAL_MAC_ALGS_CTOS] =
131 		myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
132 	}
133 	if (options.hostkeyalgorithms != NULL)
134 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
135 		    options.hostkeyalgorithms;
136 
137 	if (options.rekey_limit)
138 		packet_set_rekey_limit((u_int32_t)options.rekey_limit);
139 
140 	/* start key exchange */
141 	kex = kex_setup(myproposal);
142 	kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
143 	kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
144 	kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
145 	kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
146 	kex->client_version_string=client_version_string;
147 	kex->server_version_string=server_version_string;
148 	kex->verify_host_key=&verify_host_key_callback;
149 
150 	xxx_kex = kex;
151 
152 	dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
153 
154 	session_id2 = kex->session_id;
155 	session_id2_len = kex->session_id_len;
156 
157 #ifdef DEBUG_KEXDH
158 	/* send 1st encrypted/maced/compressed message */
159 	packet_start(SSH2_MSG_IGNORE);
160 	packet_put_cstring("markus");
161 	packet_send();
162 	packet_write_wait();
163 #endif
164 }
165 
166 /*
167  * Authenticate user
168  */
169 
170 typedef struct Authctxt Authctxt;
171 typedef struct Authmethod Authmethod;
172 typedef struct identity Identity;
173 typedef struct idlist Idlist;
174 
175 struct identity {
176 	TAILQ_ENTRY(identity) next;
177 	AuthenticationConnection *ac;	/* set if agent supports key */
178 	Key	*key;			/* public/private key */
179 	char	*filename;		/* comment for agent-only keys */
180 	int	tried;
181 	int	isprivate;		/* key points to the private key */
182 };
183 TAILQ_HEAD(idlist, identity);
184 
185 struct Authctxt {
186 	const char *server_user;
187 	const char *local_user;
188 	const char *host;
189 	const char *service;
190 	Authmethod *method;
191 	int success;
192 	char *authlist;
193 	/* pubkey */
194 	Idlist keys;
195 	AuthenticationConnection *agent;
196 	/* hostbased */
197 	Sensitive *sensitive;
198 	/* kbd-interactive */
199 	int info_req_seen;
200 	/* generic */
201 	void *methoddata;
202 };
203 struct Authmethod {
204 	char	*name;		/* string to compare against server's list */
205 	int	(*userauth)(Authctxt *authctxt);
206 	void	(*cleanup)(Authctxt *authctxt);
207 	int	*enabled;	/* flag in option struct that enables method */
208 	int	*batch_flag;	/* flag in option struct that disables method */
209 };
210 
211 void	input_userauth_success(int, u_int32_t, void *);
212 void	input_userauth_failure(int, u_int32_t, void *);
213 void	input_userauth_banner(int, u_int32_t, void *);
214 void	input_userauth_error(int, u_int32_t, void *);
215 void	input_userauth_info_req(int, u_int32_t, void *);
216 void	input_userauth_pk_ok(int, u_int32_t, void *);
217 void	input_userauth_passwd_changereq(int, u_int32_t, void *);
218 void	input_userauth_jpake_server_step1(int, u_int32_t, void *);
219 void	input_userauth_jpake_server_step2(int, u_int32_t, void *);
220 void	input_userauth_jpake_server_confirm(int, u_int32_t, void *);
221 
222 int	userauth_none(Authctxt *);
223 int	userauth_pubkey(Authctxt *);
224 int	userauth_passwd(Authctxt *);
225 int	userauth_kbdint(Authctxt *);
226 int	userauth_hostbased(Authctxt *);
227 int	userauth_jpake(Authctxt *);
228 
229 void	userauth_jpake_cleanup(Authctxt *);
230 
231 #ifdef GSSAPI
232 int	userauth_gssapi(Authctxt *authctxt);
233 void	input_gssapi_response(int type, u_int32_t, void *);
234 void	input_gssapi_token(int type, u_int32_t, void *);
235 void	input_gssapi_hash(int type, u_int32_t, void *);
236 void	input_gssapi_error(int, u_int32_t, void *);
237 void	input_gssapi_errtok(int, u_int32_t, void *);
238 #endif
239 
240 void	userauth(Authctxt *, char *);
241 
242 static int sign_and_send_pubkey(Authctxt *, Identity *);
243 static void pubkey_prepare(Authctxt *);
244 static void pubkey_cleanup(Authctxt *);
245 static Key *load_identity_file(char *);
246 
247 static Authmethod *authmethod_get(char *authlist);
248 static Authmethod *authmethod_lookup(const char *name);
249 static char *authmethods_get(void);
250 
251 Authmethod authmethods[] = {
252 #ifdef GSSAPI
253 	{"gssapi-with-mic",
254 		userauth_gssapi,
255 		NULL,
256 		&options.gss_authentication,
257 		NULL},
258 #endif
259 	{"hostbased",
260 		userauth_hostbased,
261 		NULL,
262 		&options.hostbased_authentication,
263 		NULL},
264 	{"publickey",
265 		userauth_pubkey,
266 		NULL,
267 		&options.pubkey_authentication,
268 		NULL},
269 #ifdef JPAKE
270 	{"jpake-01@openssh.com",
271 		userauth_jpake,
272 		userauth_jpake_cleanup,
273 		&options.zero_knowledge_password_authentication,
274 		&options.batch_mode},
275 #endif
276 	{"keyboard-interactive",
277 		userauth_kbdint,
278 		NULL,
279 		&options.kbd_interactive_authentication,
280 		&options.batch_mode},
281 	{"password",
282 		userauth_passwd,
283 		NULL,
284 		&options.password_authentication,
285 		&options.batch_mode},
286 	{"none",
287 		userauth_none,
288 		NULL,
289 		NULL,
290 		NULL},
291 	{NULL, NULL, NULL, NULL, NULL}
292 };
293 
294 void
295 ssh_userauth2(const char *local_user, const char *server_user, char *host,
296     Sensitive *sensitive)
297 {
298 	Authctxt authctxt;
299 	int type;
300 
301 	if (options.challenge_response_authentication)
302 		options.kbd_interactive_authentication = 1;
303 
304 	packet_start(SSH2_MSG_SERVICE_REQUEST);
305 	packet_put_cstring("ssh-userauth");
306 	packet_send();
307 	debug("SSH2_MSG_SERVICE_REQUEST sent");
308 	packet_write_wait();
309 	type = packet_read();
310 	if (type != SSH2_MSG_SERVICE_ACCEPT)
311 		fatal("Server denied authentication request: %d", type);
312 	if (packet_remaining() > 0) {
313 		char *reply = packet_get_string(NULL);
314 		debug2("service_accept: %s", reply);
315 		xfree(reply);
316 	} else {
317 		debug2("buggy server: service_accept w/o service");
318 	}
319 	packet_check_eom();
320 	debug("SSH2_MSG_SERVICE_ACCEPT received");
321 
322 	if (options.preferred_authentications == NULL)
323 		options.preferred_authentications = authmethods_get();
324 
325 	/* setup authentication context */
326 	memset(&authctxt, 0, sizeof(authctxt));
327 	pubkey_prepare(&authctxt);
328 	authctxt.server_user = server_user;
329 	authctxt.local_user = local_user;
330 	authctxt.host = host;
331 	authctxt.service = "ssh-connection";		/* service name */
332 	authctxt.success = 0;
333 	authctxt.method = authmethod_lookup("none");
334 	authctxt.authlist = NULL;
335 	authctxt.methoddata = NULL;
336 	authctxt.sensitive = sensitive;
337 	authctxt.info_req_seen = 0;
338 	if (authctxt.method == NULL)
339 		fatal("ssh_userauth2: internal error: cannot send userauth none request");
340 
341 	/* initial userauth request */
342 	userauth_none(&authctxt);
343 
344 	dispatch_init(&input_userauth_error);
345 	dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
346 	dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
347 	dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
348 	dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt);	/* loop until success */
349 
350 	pubkey_cleanup(&authctxt);
351 	dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
352 
353 	debug("Authentication succeeded (%s).", authctxt.method->name);
354 }
355 
356 void
357 userauth(Authctxt *authctxt, char *authlist)
358 {
359 	if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
360 		authctxt->method->cleanup(authctxt);
361 
362 	if (authctxt->methoddata) {
363 		xfree(authctxt->methoddata);
364 		authctxt->methoddata = NULL;
365 	}
366 	if (authlist == NULL) {
367 		authlist = authctxt->authlist;
368 	} else {
369 		if (authctxt->authlist)
370 			xfree(authctxt->authlist);
371 		authctxt->authlist = authlist;
372 	}
373 	for (;;) {
374 		Authmethod *method = authmethod_get(authlist);
375 		if (method == NULL)
376 			fatal("Permission denied (%s).", authlist);
377 		authctxt->method = method;
378 
379 		/* reset the per method handler */
380 		dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
381 		    SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
382 
383 		/* and try new method */
384 		if (method->userauth(authctxt) != 0) {
385 			debug2("we sent a %s packet, wait for reply", method->name);
386 			break;
387 		} else {
388 			debug2("we did not send a packet, disable method");
389 			method->enabled = NULL;
390 		}
391 	}
392 }
393 
394 /* ARGSUSED */
395 void
396 input_userauth_error(int type, u_int32_t seq, void *ctxt)
397 {
398 	fatal("input_userauth_error: bad message during authentication: "
399 	    "type %d", type);
400 }
401 
402 /* ARGSUSED */
403 void
404 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
405 {
406 	char *msg, *raw, *lang;
407 	u_int len;
408 
409 	debug3("input_userauth_banner");
410 	raw = packet_get_string(&len);
411 	lang = packet_get_string(NULL);
412 	if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
413 		if (len > 65536)
414 			len = 65536;
415 		msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
416 		strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL);
417 		fprintf(stderr, "%s", msg);
418 		xfree(msg);
419 	}
420 	xfree(raw);
421 	xfree(lang);
422 }
423 
424 /* ARGSUSED */
425 void
426 input_userauth_success(int type, u_int32_t seq, void *ctxt)
427 {
428 	Authctxt *authctxt = ctxt;
429 	if (authctxt == NULL)
430 		fatal("input_userauth_success: no authentication context");
431 	if (authctxt->authlist) {
432 		xfree(authctxt->authlist);
433 		authctxt->authlist = NULL;
434 	}
435 	if (authctxt->methoddata) {
436 		xfree(authctxt->methoddata);
437 		authctxt->methoddata = NULL;
438 	}
439 	authctxt->success = 1;			/* break out */
440 }
441 
442 /* ARGSUSED */
443 void
444 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
445 {
446 	Authctxt *authctxt = ctxt;
447 	char *authlist = NULL;
448 	int partial;
449 
450 	if (authctxt == NULL)
451 		fatal("input_userauth_failure: no authentication context");
452 
453 	authlist = packet_get_string(NULL);
454 	partial = packet_get_char();
455 	packet_check_eom();
456 
457 	if (partial != 0)
458 		logit("Authenticated with partial success.");
459 	debug("Authentications that can continue: %s", authlist);
460 
461 	userauth(authctxt, authlist);
462 }
463 
464 /* ARGSUSED */
465 void
466 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
467 {
468 	Authctxt *authctxt = ctxt;
469 	Key *key = NULL;
470 	Identity *id = NULL;
471 	Buffer b;
472 	int pktype, sent = 0;
473 	u_int alen, blen;
474 	char *pkalg, *fp;
475 	u_char *pkblob;
476 
477 	if (authctxt == NULL)
478 		fatal("input_userauth_pk_ok: no authentication context");
479 	if (datafellows & SSH_BUG_PKOK) {
480 		/* this is similar to SSH_BUG_PKAUTH */
481 		debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
482 		pkblob = packet_get_string(&blen);
483 		buffer_init(&b);
484 		buffer_append(&b, pkblob, blen);
485 		pkalg = buffer_get_string(&b, &alen);
486 		buffer_free(&b);
487 	} else {
488 		pkalg = packet_get_string(&alen);
489 		pkblob = packet_get_string(&blen);
490 	}
491 	packet_check_eom();
492 
493 	debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
494 
495 	if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
496 		debug("unknown pkalg %s", pkalg);
497 		goto done;
498 	}
499 	if ((key = key_from_blob(pkblob, blen)) == NULL) {
500 		debug("no key from blob. pkalg %s", pkalg);
501 		goto done;
502 	}
503 	if (key->type != pktype) {
504 		error("input_userauth_pk_ok: type mismatch "
505 		    "for decoded key (received %d, expected %d)",
506 		    key->type, pktype);
507 		goto done;
508 	}
509 	fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
510 	debug2("input_userauth_pk_ok: fp %s", fp);
511 	xfree(fp);
512 
513 	/*
514 	 * search keys in the reverse order, because last candidate has been
515 	 * moved to the end of the queue.  this also avoids confusion by
516 	 * duplicate keys
517 	 */
518 	TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
519 		if (key_equal(key, id->key)) {
520 			sent = sign_and_send_pubkey(authctxt, id);
521 			break;
522 		}
523 	}
524 done:
525 	if (key != NULL)
526 		key_free(key);
527 	xfree(pkalg);
528 	xfree(pkblob);
529 
530 	/* try another method if we did not send a packet */
531 	if (sent == 0)
532 		userauth(authctxt, NULL);
533 }
534 
535 #ifdef GSSAPI
536 int
537 userauth_gssapi(Authctxt *authctxt)
538 {
539 	Gssctxt *gssctxt = NULL;
540 	static gss_OID_set gss_supported = NULL;
541 	static u_int mech = 0;
542 	OM_uint32 min;
543 	int ok = 0;
544 
545 	/* Try one GSSAPI method at a time, rather than sending them all at
546 	 * once. */
547 
548 	if (gss_supported == NULL)
549 		gss_indicate_mechs(&min, &gss_supported);
550 
551 	/* Check to see if the mechanism is usable before we offer it */
552 	while (mech < gss_supported->count && !ok) {
553 		/* My DER encoding requires length<128 */
554 		if (gss_supported->elements[mech].length < 128 &&
555 		    ssh_gssapi_check_mechanism(&gssctxt,
556 		    &gss_supported->elements[mech], authctxt->host)) {
557 			ok = 1; /* Mechanism works */
558 		} else {
559 			mech++;
560 		}
561 	}
562 
563 	if (!ok)
564 		return 0;
565 
566 	authctxt->methoddata=(void *)gssctxt;
567 
568 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
569 	packet_put_cstring(authctxt->server_user);
570 	packet_put_cstring(authctxt->service);
571 	packet_put_cstring(authctxt->method->name);
572 
573 	packet_put_int(1);
574 
575 	packet_put_int((gss_supported->elements[mech].length) + 2);
576 	packet_put_char(SSH_GSS_OIDTYPE);
577 	packet_put_char(gss_supported->elements[mech].length);
578 	packet_put_raw(gss_supported->elements[mech].elements,
579 	    gss_supported->elements[mech].length);
580 
581 	packet_send();
582 
583 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
584 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
585 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
586 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
587 
588 	mech++; /* Move along to next candidate */
589 
590 	return 1;
591 }
592 
593 static OM_uint32
594 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
595 {
596 	Authctxt *authctxt = ctxt;
597 	Gssctxt *gssctxt = authctxt->methoddata;
598 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
599 	gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
600 	gss_buffer_desc gssbuf;
601 	OM_uint32 status, ms, flags;
602 	Buffer b;
603 
604 	status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
605 	    recv_tok, &send_tok, &flags);
606 
607 	if (send_tok.length > 0) {
608 		if (GSS_ERROR(status))
609 			packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
610 		else
611 			packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
612 
613 		packet_put_string(send_tok.value, send_tok.length);
614 		packet_send();
615 		gss_release_buffer(&ms, &send_tok);
616 	}
617 
618 	if (status == GSS_S_COMPLETE) {
619 		/* send either complete or MIC, depending on mechanism */
620 		if (!(flags & GSS_C_INTEG_FLAG)) {
621 			packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
622 			packet_send();
623 		} else {
624 			ssh_gssapi_buildmic(&b, authctxt->server_user,
625 			    authctxt->service, "gssapi-with-mic");
626 
627 			gssbuf.value = buffer_ptr(&b);
628 			gssbuf.length = buffer_len(&b);
629 
630 			status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
631 
632 			if (!GSS_ERROR(status)) {
633 				packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
634 				packet_put_string(mic.value, mic.length);
635 
636 				packet_send();
637 			}
638 
639 			buffer_free(&b);
640 			gss_release_buffer(&ms, &mic);
641 		}
642 	}
643 
644 	return status;
645 }
646 
647 /* ARGSUSED */
648 void
649 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
650 {
651 	Authctxt *authctxt = ctxt;
652 	Gssctxt *gssctxt;
653 	int oidlen;
654 	char *oidv;
655 
656 	if (authctxt == NULL)
657 		fatal("input_gssapi_response: no authentication context");
658 	gssctxt = authctxt->methoddata;
659 
660 	/* Setup our OID */
661 	oidv = packet_get_string(&oidlen);
662 
663 	if (oidlen <= 2 ||
664 	    oidv[0] != SSH_GSS_OIDTYPE ||
665 	    oidv[1] != oidlen - 2) {
666 		xfree(oidv);
667 		debug("Badly encoded mechanism OID received");
668 		userauth(authctxt, NULL);
669 		return;
670 	}
671 
672 	if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
673 		fatal("Server returned different OID than expected");
674 
675 	packet_check_eom();
676 
677 	xfree(oidv);
678 
679 	if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
680 		/* Start again with next method on list */
681 		debug("Trying to start again");
682 		userauth(authctxt, NULL);
683 		return;
684 	}
685 }
686 
687 /* ARGSUSED */
688 void
689 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
690 {
691 	Authctxt *authctxt = ctxt;
692 	gss_buffer_desc recv_tok;
693 	OM_uint32 status;
694 	u_int slen;
695 
696 	if (authctxt == NULL)
697 		fatal("input_gssapi_response: no authentication context");
698 
699 	recv_tok.value = packet_get_string(&slen);
700 	recv_tok.length = slen;	/* safe typecast */
701 
702 	packet_check_eom();
703 
704 	status = process_gssapi_token(ctxt, &recv_tok);
705 
706 	xfree(recv_tok.value);
707 
708 	if (GSS_ERROR(status)) {
709 		/* Start again with the next method in the list */
710 		userauth(authctxt, NULL);
711 		return;
712 	}
713 }
714 
715 /* ARGSUSED */
716 void
717 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
718 {
719 	Authctxt *authctxt = ctxt;
720 	Gssctxt *gssctxt;
721 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
722 	gss_buffer_desc recv_tok;
723 	OM_uint32 status, ms;
724 	u_int len;
725 
726 	if (authctxt == NULL)
727 		fatal("input_gssapi_response: no authentication context");
728 	gssctxt = authctxt->methoddata;
729 
730 	recv_tok.value = packet_get_string(&len);
731 	recv_tok.length = len;
732 
733 	packet_check_eom();
734 
735 	/* Stick it into GSSAPI and see what it says */
736 	status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
737 	    &recv_tok, &send_tok, NULL);
738 
739 	xfree(recv_tok.value);
740 	gss_release_buffer(&ms, &send_tok);
741 
742 	/* Server will be returning a failed packet after this one */
743 }
744 
745 /* ARGSUSED */
746 void
747 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
748 {
749 	OM_uint32 maj, min;
750 	char *msg;
751 	char *lang;
752 
753 	maj=packet_get_int();
754 	min=packet_get_int();
755 	msg=packet_get_string(NULL);
756 	lang=packet_get_string(NULL);
757 
758 	packet_check_eom();
759 
760 	debug("Server GSSAPI Error:\n%s", msg);
761 	xfree(msg);
762 	xfree(lang);
763 }
764 #endif /* GSSAPI */
765 
766 int
767 userauth_none(Authctxt *authctxt)
768 {
769 	/* initial userauth request */
770 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
771 	packet_put_cstring(authctxt->server_user);
772 	packet_put_cstring(authctxt->service);
773 	packet_put_cstring(authctxt->method->name);
774 	packet_send();
775 	return 1;
776 }
777 
778 int
779 userauth_passwd(Authctxt *authctxt)
780 {
781 	static int attempt = 0;
782 	char prompt[150];
783 	char *password;
784 
785 	if (attempt++ >= options.number_of_password_prompts)
786 		return 0;
787 
788 	if (attempt != 1)
789 		error("Permission denied, please try again.");
790 
791 	snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
792 	    authctxt->server_user, authctxt->host);
793 	password = read_passphrase(prompt, 0);
794 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
795 	packet_put_cstring(authctxt->server_user);
796 	packet_put_cstring(authctxt->service);
797 	packet_put_cstring(authctxt->method->name);
798 	packet_put_char(0);
799 	packet_put_cstring(password);
800 	memset(password, 0, strlen(password));
801 	xfree(password);
802 	packet_add_padding(64);
803 	packet_send();
804 
805 	dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
806 	    &input_userauth_passwd_changereq);
807 
808 	return 1;
809 }
810 
811 /*
812  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
813  */
814 /* ARGSUSED */
815 void
816 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
817 {
818 	Authctxt *authctxt = ctxt;
819 	char *info, *lang, *password = NULL, *retype = NULL;
820 	char prompt[150];
821 
822 	debug2("input_userauth_passwd_changereq");
823 
824 	if (authctxt == NULL)
825 		fatal("input_userauth_passwd_changereq: "
826 		    "no authentication context");
827 
828 	info = packet_get_string(NULL);
829 	lang = packet_get_string(NULL);
830 	if (strlen(info) > 0)
831 		logit("%s", info);
832 	xfree(info);
833 	xfree(lang);
834 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
835 	packet_put_cstring(authctxt->server_user);
836 	packet_put_cstring(authctxt->service);
837 	packet_put_cstring(authctxt->method->name);
838 	packet_put_char(1);			/* additional info */
839 	snprintf(prompt, sizeof(prompt),
840 	    "Enter %.30s@%.128s's old password: ",
841 	    authctxt->server_user, authctxt->host);
842 	password = read_passphrase(prompt, 0);
843 	packet_put_cstring(password);
844 	memset(password, 0, strlen(password));
845 	xfree(password);
846 	password = NULL;
847 	while (password == NULL) {
848 		snprintf(prompt, sizeof(prompt),
849 		    "Enter %.30s@%.128s's new password: ",
850 		    authctxt->server_user, authctxt->host);
851 		password = read_passphrase(prompt, RP_ALLOW_EOF);
852 		if (password == NULL) {
853 			/* bail out */
854 			return;
855 		}
856 		snprintf(prompt, sizeof(prompt),
857 		    "Retype %.30s@%.128s's new password: ",
858 		    authctxt->server_user, authctxt->host);
859 		retype = read_passphrase(prompt, 0);
860 		if (strcmp(password, retype) != 0) {
861 			memset(password, 0, strlen(password));
862 			xfree(password);
863 			logit("Mismatch; try again, EOF to quit.");
864 			password = NULL;
865 		}
866 		memset(retype, 0, strlen(retype));
867 		xfree(retype);
868 	}
869 	packet_put_cstring(password);
870 	memset(password, 0, strlen(password));
871 	xfree(password);
872 	packet_add_padding(64);
873 	packet_send();
874 
875 	dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
876 	    &input_userauth_passwd_changereq);
877 }
878 
879 #ifdef JPAKE
880 static char *
881 pw_encrypt(const char *password, const char *crypt_scheme, const char *salt)
882 {
883 	/* OpenBSD crypt(3) handles all of these */
884 	if (strcmp(crypt_scheme, "crypt") == 0 ||
885 	    strcmp(crypt_scheme, "bcrypt") == 0 ||
886 	    strcmp(crypt_scheme, "md5crypt") == 0 ||
887 	    strcmp(crypt_scheme, "crypt-extended") == 0)
888 		return xstrdup(crypt(password, salt));
889 	error("%s: unsupported password encryption scheme \"%.100s\"",
890 	    __func__, crypt_scheme);
891 	return NULL;
892 }
893 
894 static BIGNUM *
895 jpake_password_to_secret(Authctxt *authctxt, const char *crypt_scheme,
896     const char *salt)
897 {
898 	char prompt[256], *password, *crypted;
899 	u_char *secret;
900 	u_int secret_len;
901 	BIGNUM *ret;
902 
903 	snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password (JPAKE): ",
904 	    authctxt->server_user, authctxt->host);
905 	password = read_passphrase(prompt, 0);
906 
907 	if ((crypted = pw_encrypt(password, crypt_scheme, salt)) == NULL) {
908 		logit("Disabling %s authentication", authctxt->method->name);
909 		authctxt->method->enabled = NULL;
910 		/* Continue with an empty password to fail gracefully */
911 		crypted = xstrdup("");
912 	}
913 
914 #ifdef JPAKE_DEBUG
915 	debug3("%s: salt = %s", __func__, salt);
916 	debug3("%s: scheme = %s", __func__, crypt_scheme);
917 	debug3("%s: crypted = %s", __func__, crypted);
918 #endif
919 
920 	if (hash_buffer(crypted, strlen(crypted), EVP_sha256(),
921 	    &secret, &secret_len) != 0)
922 		fatal("%s: hash_buffer", __func__);
923 
924 	bzero(password, strlen(password));
925 	bzero(crypted, strlen(crypted));
926 	xfree(password);
927 	xfree(crypted);
928 
929 	if ((ret = BN_bin2bn(secret, secret_len, NULL)) == NULL)
930 		fatal("%s: BN_bin2bn (secret)", __func__);
931 	bzero(secret, secret_len);
932 	xfree(secret);
933 
934 	return ret;
935 }
936 
937 /* ARGSUSED */
938 void
939 input_userauth_jpake_server_step1(int type, u_int32_t seq, void *ctxt)
940 {
941 	Authctxt *authctxt = ctxt;
942 	struct jpake_ctx *pctx = authctxt->methoddata;
943 	u_char *x3_proof, *x4_proof, *x2_s_proof;
944 	u_int x3_proof_len, x4_proof_len, x2_s_proof_len;
945 	char *crypt_scheme, *salt;
946 
947 	/* Disable this message */
948 	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1, NULL);
949 
950 	if ((pctx->g_x3 = BN_new()) == NULL ||
951 	    (pctx->g_x4 = BN_new()) == NULL)
952 		fatal("%s: BN_new", __func__);
953 
954 	/* Fetch step 1 values */
955 	crypt_scheme = packet_get_string(NULL);
956 	salt = packet_get_string(NULL);
957 	pctx->server_id = packet_get_string(&pctx->server_id_len);
958 	packet_get_bignum2(pctx->g_x3);
959 	packet_get_bignum2(pctx->g_x4);
960 	x3_proof = packet_get_string(&x3_proof_len);
961 	x4_proof = packet_get_string(&x4_proof_len);
962 	packet_check_eom();
963 
964 	JPAKE_DEBUG_CTX((pctx, "step 1 received in %s", __func__));
965 
966 	/* Obtain password and derive secret */
967 	pctx->s = jpake_password_to_secret(authctxt, crypt_scheme, salt);
968 	bzero(crypt_scheme, strlen(crypt_scheme));
969 	bzero(salt, strlen(salt));
970 	xfree(crypt_scheme);
971 	xfree(salt);
972 	JPAKE_DEBUG_BN((pctx->s, "%s: s = ", __func__));
973 
974 	/* Calculate step 2 values */
975 	jpake_step2(pctx->grp, pctx->s, pctx->g_x1,
976 	    pctx->g_x3, pctx->g_x4, pctx->x2,
977 	    pctx->server_id, pctx->server_id_len,
978 	    pctx->client_id, pctx->client_id_len,
979 	    x3_proof, x3_proof_len,
980 	    x4_proof, x4_proof_len,
981 	    &pctx->a,
982 	    &x2_s_proof, &x2_s_proof_len);
983 
984 	bzero(x3_proof, x3_proof_len);
985 	bzero(x4_proof, x4_proof_len);
986 	xfree(x3_proof);
987 	xfree(x4_proof);
988 
989 	JPAKE_DEBUG_CTX((pctx, "step 2 sending in %s", __func__));
990 
991 	/* Send values for step 2 */
992 	packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2);
993 	packet_put_bignum2(pctx->a);
994 	packet_put_string(x2_s_proof, x2_s_proof_len);
995 	packet_send();
996 
997 	bzero(x2_s_proof, x2_s_proof_len);
998 	xfree(x2_s_proof);
999 
1000 	/* Expect step 2 packet from peer */
1001 	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2,
1002 	    input_userauth_jpake_server_step2);
1003 }
1004 
1005 /* ARGSUSED */
1006 void
1007 input_userauth_jpake_server_step2(int type, u_int32_t seq, void *ctxt)
1008 {
1009 	Authctxt *authctxt = ctxt;
1010 	struct jpake_ctx *pctx = authctxt->methoddata;
1011 	u_char *x4_s_proof;
1012 	u_int x4_s_proof_len;
1013 
1014 	/* Disable this message */
1015 	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2, NULL);
1016 
1017 	if ((pctx->b = BN_new()) == NULL)
1018 		fatal("%s: BN_new", __func__);
1019 
1020 	/* Fetch step 2 values */
1021 	packet_get_bignum2(pctx->b);
1022 	x4_s_proof = packet_get_string(&x4_s_proof_len);
1023 	packet_check_eom();
1024 
1025 	JPAKE_DEBUG_CTX((pctx, "step 2 received in %s", __func__));
1026 
1027 	/* Derive shared key and calculate confirmation hash */
1028 	jpake_key_confirm(pctx->grp, pctx->s, pctx->b,
1029 	    pctx->x2, pctx->g_x1, pctx->g_x2, pctx->g_x3, pctx->g_x4,
1030 	    pctx->client_id, pctx->client_id_len,
1031 	    pctx->server_id, pctx->server_id_len,
1032 	    session_id2, session_id2_len,
1033 	    x4_s_proof, x4_s_proof_len,
1034 	    &pctx->k,
1035 	    &pctx->h_k_cid_sessid, &pctx->h_k_cid_sessid_len);
1036 
1037 	bzero(x4_s_proof, x4_s_proof_len);
1038 	xfree(x4_s_proof);
1039 
1040 	JPAKE_DEBUG_CTX((pctx, "confirm sending in %s", __func__));
1041 
1042 	/* Send key confirmation proof */
1043 	packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM);
1044 	packet_put_string(pctx->h_k_cid_sessid, pctx->h_k_cid_sessid_len);
1045 	packet_send();
1046 
1047 	/* Expect confirmation from peer */
1048 	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM,
1049 	    input_userauth_jpake_server_confirm);
1050 }
1051 
1052 /* ARGSUSED */
1053 void
1054 input_userauth_jpake_server_confirm(int type, u_int32_t seq, void *ctxt)
1055 {
1056 	Authctxt *authctxt = ctxt;
1057 	struct jpake_ctx *pctx = authctxt->methoddata;
1058 
1059 	/* Disable this message */
1060 	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM, NULL);
1061 
1062 	pctx->h_k_sid_sessid = packet_get_string(&pctx->h_k_sid_sessid_len);
1063 	packet_check_eom();
1064 
1065 	JPAKE_DEBUG_CTX((pctx, "confirm received in %s", __func__));
1066 
1067 	/* Verify expected confirmation hash */
1068 	if (jpake_check_confirm(pctx->k,
1069 	    pctx->server_id, pctx->server_id_len,
1070 	    session_id2, session_id2_len,
1071 	    pctx->h_k_sid_sessid, pctx->h_k_sid_sessid_len) == 1)
1072 		debug("%s: %s success", __func__, authctxt->method->name);
1073 	else {
1074 		debug("%s: confirmation mismatch", __func__);
1075 		/* XXX stash this so if auth succeeds then we can warn/kill */
1076 	}
1077 
1078 	userauth_jpake_cleanup(authctxt);
1079 }
1080 #endif /* JPAKE */
1081 
1082 static int
1083 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
1084     u_char *data, u_int datalen)
1085 {
1086 	Key *prv;
1087 	int ret;
1088 
1089 	/* the agent supports this key */
1090 	if (id->ac)
1091 		return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1092 		    data, datalen));
1093 	/*
1094 	 * we have already loaded the private key or
1095 	 * the private key is stored in external hardware
1096 	 */
1097 	if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1098 		return (key_sign(id->key, sigp, lenp, data, datalen));
1099 	/* load the private key from the file */
1100 	if ((prv = load_identity_file(id->filename)) == NULL)
1101 		return (-1);
1102 	ret = key_sign(prv, sigp, lenp, data, datalen);
1103 	key_free(prv);
1104 	return (ret);
1105 }
1106 
1107 static int
1108 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1109 {
1110 	Buffer b;
1111 	u_char *blob, *signature;
1112 	u_int bloblen, slen;
1113 	u_int skip = 0;
1114 	int ret = -1;
1115 	int have_sig = 1;
1116 
1117 	debug3("sign_and_send_pubkey");
1118 
1119 	if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1120 		/* we cannot handle this key */
1121 		debug3("sign_and_send_pubkey: cannot handle key");
1122 		return 0;
1123 	}
1124 	/* data to be signed */
1125 	buffer_init(&b);
1126 	if (datafellows & SSH_OLD_SESSIONID) {
1127 		buffer_append(&b, session_id2, session_id2_len);
1128 		skip = session_id2_len;
1129 	} else {
1130 		buffer_put_string(&b, session_id2, session_id2_len);
1131 		skip = buffer_len(&b);
1132 	}
1133 	buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1134 	buffer_put_cstring(&b, authctxt->server_user);
1135 	buffer_put_cstring(&b,
1136 	    datafellows & SSH_BUG_PKSERVICE ?
1137 	    "ssh-userauth" :
1138 	    authctxt->service);
1139 	if (datafellows & SSH_BUG_PKAUTH) {
1140 		buffer_put_char(&b, have_sig);
1141 	} else {
1142 		buffer_put_cstring(&b, authctxt->method->name);
1143 		buffer_put_char(&b, have_sig);
1144 		buffer_put_cstring(&b, key_ssh_name(id->key));
1145 	}
1146 	buffer_put_string(&b, blob, bloblen);
1147 
1148 	/* generate signature */
1149 	ret = identity_sign(id, &signature, &slen,
1150 	    buffer_ptr(&b), buffer_len(&b));
1151 	if (ret == -1) {
1152 		xfree(blob);
1153 		buffer_free(&b);
1154 		return 0;
1155 	}
1156 #ifdef DEBUG_PK
1157 	buffer_dump(&b);
1158 #endif
1159 	if (datafellows & SSH_BUG_PKSERVICE) {
1160 		buffer_clear(&b);
1161 		buffer_append(&b, session_id2, session_id2_len);
1162 		skip = session_id2_len;
1163 		buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1164 		buffer_put_cstring(&b, authctxt->server_user);
1165 		buffer_put_cstring(&b, authctxt->service);
1166 		buffer_put_cstring(&b, authctxt->method->name);
1167 		buffer_put_char(&b, have_sig);
1168 		if (!(datafellows & SSH_BUG_PKAUTH))
1169 			buffer_put_cstring(&b, key_ssh_name(id->key));
1170 		buffer_put_string(&b, blob, bloblen);
1171 	}
1172 	xfree(blob);
1173 
1174 	/* append signature */
1175 	buffer_put_string(&b, signature, slen);
1176 	xfree(signature);
1177 
1178 	/* skip session id and packet type */
1179 	if (buffer_len(&b) < skip + 1)
1180 		fatal("userauth_pubkey: internal error");
1181 	buffer_consume(&b, skip + 1);
1182 
1183 	/* put remaining data from buffer into packet */
1184 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
1185 	packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1186 	buffer_free(&b);
1187 	packet_send();
1188 
1189 	return 1;
1190 }
1191 
1192 static int
1193 send_pubkey_test(Authctxt *authctxt, Identity *id)
1194 {
1195 	u_char *blob;
1196 	u_int bloblen, have_sig = 0;
1197 
1198 	debug3("send_pubkey_test");
1199 
1200 	if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1201 		/* we cannot handle this key */
1202 		debug3("send_pubkey_test: cannot handle key");
1203 		return 0;
1204 	}
1205 	/* register callback for USERAUTH_PK_OK message */
1206 	dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1207 
1208 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
1209 	packet_put_cstring(authctxt->server_user);
1210 	packet_put_cstring(authctxt->service);
1211 	packet_put_cstring(authctxt->method->name);
1212 	packet_put_char(have_sig);
1213 	if (!(datafellows & SSH_BUG_PKAUTH))
1214 		packet_put_cstring(key_ssh_name(id->key));
1215 	packet_put_string(blob, bloblen);
1216 	xfree(blob);
1217 	packet_send();
1218 	return 1;
1219 }
1220 
1221 static Key *
1222 load_identity_file(char *filename)
1223 {
1224 	Key *private;
1225 	char prompt[300], *passphrase;
1226 	int perm_ok, quit, i;
1227 	struct stat st;
1228 
1229 	if (stat(filename, &st) < 0) {
1230 		debug3("no such identity: %s", filename);
1231 		return NULL;
1232 	}
1233 	private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1234 	if (!perm_ok)
1235 		return NULL;
1236 	if (private == NULL) {
1237 		if (options.batch_mode)
1238 			return NULL;
1239 		snprintf(prompt, sizeof prompt,
1240 		    "Enter passphrase for key '%.100s': ", filename);
1241 		for (i = 0; i < options.number_of_password_prompts; i++) {
1242 			passphrase = read_passphrase(prompt, 0);
1243 			if (strcmp(passphrase, "") != 0) {
1244 				private = key_load_private_type(KEY_UNSPEC,
1245 				    filename, passphrase, NULL, NULL);
1246 				quit = 0;
1247 			} else {
1248 				debug2("no passphrase given, try next key");
1249 				quit = 1;
1250 			}
1251 			memset(passphrase, 0, strlen(passphrase));
1252 			xfree(passphrase);
1253 			if (private != NULL || quit)
1254 				break;
1255 			debug2("bad passphrase given, try again...");
1256 		}
1257 	}
1258 	return private;
1259 }
1260 
1261 /*
1262  * try keys in the following order:
1263  *	1. agent keys that are found in the config file
1264  *	2. other agent keys
1265  *	3. keys that are only listed in the config file
1266  */
1267 static void
1268 pubkey_prepare(Authctxt *authctxt)
1269 {
1270 	Identity *id;
1271 	Idlist agent, files, *preferred;
1272 	Key *key;
1273 	AuthenticationConnection *ac;
1274 	char *comment;
1275 	int i, found;
1276 
1277 	TAILQ_INIT(&agent);	/* keys from the agent */
1278 	TAILQ_INIT(&files);	/* keys from the config file */
1279 	preferred = &authctxt->keys;
1280 	TAILQ_INIT(preferred);	/* preferred order of keys */
1281 
1282 	/* list of keys stored in the filesystem */
1283 	for (i = 0; i < options.num_identity_files; i++) {
1284 		key = options.identity_keys[i];
1285 		if (key && key->type == KEY_RSA1)
1286 			continue;
1287 		options.identity_keys[i] = NULL;
1288 		id = xcalloc(1, sizeof(*id));
1289 		id->key = key;
1290 		id->filename = xstrdup(options.identity_files[i]);
1291 		TAILQ_INSERT_TAIL(&files, id, next);
1292 	}
1293 	/* list of keys supported by the agent */
1294 	if ((ac = ssh_get_authentication_connection())) {
1295 		for (key = ssh_get_first_identity(ac, &comment, 2);
1296 		    key != NULL;
1297 		    key = ssh_get_next_identity(ac, &comment, 2)) {
1298 			found = 0;
1299 			TAILQ_FOREACH(id, &files, next) {
1300 				/* agent keys from the config file are preferred */
1301 				if (key_equal(key, id->key)) {
1302 					key_free(key);
1303 					xfree(comment);
1304 					TAILQ_REMOVE(&files, id, next);
1305 					TAILQ_INSERT_TAIL(preferred, id, next);
1306 					id->ac = ac;
1307 					found = 1;
1308 					break;
1309 				}
1310 			}
1311 			if (!found && !options.identities_only) {
1312 				id = xcalloc(1, sizeof(*id));
1313 				id->key = key;
1314 				id->filename = comment;
1315 				id->ac = ac;
1316 				TAILQ_INSERT_TAIL(&agent, id, next);
1317 			}
1318 		}
1319 		/* append remaining agent keys */
1320 		for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1321 			TAILQ_REMOVE(&agent, id, next);
1322 			TAILQ_INSERT_TAIL(preferred, id, next);
1323 		}
1324 		authctxt->agent = ac;
1325 	}
1326 	/* append remaining keys from the config file */
1327 	for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1328 		TAILQ_REMOVE(&files, id, next);
1329 		TAILQ_INSERT_TAIL(preferred, id, next);
1330 	}
1331 	TAILQ_FOREACH(id, preferred, next) {
1332 		debug2("key: %s (%p)", id->filename, id->key);
1333 	}
1334 }
1335 
1336 static void
1337 pubkey_cleanup(Authctxt *authctxt)
1338 {
1339 	Identity *id;
1340 
1341 	if (authctxt->agent != NULL)
1342 		ssh_close_authentication_connection(authctxt->agent);
1343 	for (id = TAILQ_FIRST(&authctxt->keys); id;
1344 	    id = TAILQ_FIRST(&authctxt->keys)) {
1345 		TAILQ_REMOVE(&authctxt->keys, id, next);
1346 		if (id->key)
1347 			key_free(id->key);
1348 		if (id->filename)
1349 			xfree(id->filename);
1350 		xfree(id);
1351 	}
1352 }
1353 
1354 int
1355 userauth_pubkey(Authctxt *authctxt)
1356 {
1357 	Identity *id;
1358 	int sent = 0;
1359 
1360 	while ((id = TAILQ_FIRST(&authctxt->keys))) {
1361 		if (id->tried++)
1362 			return (0);
1363 		/* move key to the end of the queue */
1364 		TAILQ_REMOVE(&authctxt->keys, id, next);
1365 		TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1366 		/*
1367 		 * send a test message if we have the public key. for
1368 		 * encrypted keys we cannot do this and have to load the
1369 		 * private key instead
1370 		 */
1371 		if (id->key && id->key->type != KEY_RSA1) {
1372 			debug("Offering public key: %s", id->filename);
1373 			sent = send_pubkey_test(authctxt, id);
1374 		} else if (id->key == NULL) {
1375 			debug("Trying private key: %s", id->filename);
1376 			id->key = load_identity_file(id->filename);
1377 			if (id->key != NULL) {
1378 				id->isprivate = 1;
1379 				sent = sign_and_send_pubkey(authctxt, id);
1380 				key_free(id->key);
1381 				id->key = NULL;
1382 			}
1383 		}
1384 		if (sent)
1385 			return (sent);
1386 	}
1387 	return (0);
1388 }
1389 
1390 /*
1391  * Send userauth request message specifying keyboard-interactive method.
1392  */
1393 int
1394 userauth_kbdint(Authctxt *authctxt)
1395 {
1396 	static int attempt = 0;
1397 
1398 	if (attempt++ >= options.number_of_password_prompts)
1399 		return 0;
1400 	/* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1401 	if (attempt > 1 && !authctxt->info_req_seen) {
1402 		debug3("userauth_kbdint: disable: no info_req_seen");
1403 		dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1404 		return 0;
1405 	}
1406 
1407 	debug2("userauth_kbdint");
1408 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
1409 	packet_put_cstring(authctxt->server_user);
1410 	packet_put_cstring(authctxt->service);
1411 	packet_put_cstring(authctxt->method->name);
1412 	packet_put_cstring("");					/* lang */
1413 	packet_put_cstring(options.kbd_interactive_devices ?
1414 	    options.kbd_interactive_devices : "");
1415 	packet_send();
1416 
1417 	dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1418 	return 1;
1419 }
1420 
1421 /*
1422  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1423  */
1424 void
1425 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1426 {
1427 	Authctxt *authctxt = ctxt;
1428 	char *name, *inst, *lang, *prompt, *response;
1429 	u_int num_prompts, i;
1430 	int echo = 0;
1431 
1432 	debug2("input_userauth_info_req");
1433 
1434 	if (authctxt == NULL)
1435 		fatal("input_userauth_info_req: no authentication context");
1436 
1437 	authctxt->info_req_seen = 1;
1438 
1439 	name = packet_get_string(NULL);
1440 	inst = packet_get_string(NULL);
1441 	lang = packet_get_string(NULL);
1442 	if (strlen(name) > 0)
1443 		logit("%s", name);
1444 	if (strlen(inst) > 0)
1445 		logit("%s", inst);
1446 	xfree(name);
1447 	xfree(inst);
1448 	xfree(lang);
1449 
1450 	num_prompts = packet_get_int();
1451 	/*
1452 	 * Begin to build info response packet based on prompts requested.
1453 	 * We commit to providing the correct number of responses, so if
1454 	 * further on we run into a problem that prevents this, we have to
1455 	 * be sure and clean this up and send a correct error response.
1456 	 */
1457 	packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1458 	packet_put_int(num_prompts);
1459 
1460 	debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1461 	for (i = 0; i < num_prompts; i++) {
1462 		prompt = packet_get_string(NULL);
1463 		echo = packet_get_char();
1464 
1465 		response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1466 
1467 		packet_put_cstring(response);
1468 		memset(response, 0, strlen(response));
1469 		xfree(response);
1470 		xfree(prompt);
1471 	}
1472 	packet_check_eom(); /* done with parsing incoming message. */
1473 
1474 	packet_add_padding(64);
1475 	packet_send();
1476 }
1477 
1478 static int
1479 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1480     u_char *data, u_int datalen)
1481 {
1482 	Buffer b;
1483 	struct stat st;
1484 	pid_t pid;
1485 	int to[2], from[2], status, version = 2;
1486 
1487 	debug2("ssh_keysign called");
1488 
1489 	if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1490 		error("ssh_keysign: no installed: %s", strerror(errno));
1491 		return -1;
1492 	}
1493 	if (fflush(stdout) != 0)
1494 		error("ssh_keysign: fflush: %s", strerror(errno));
1495 	if (pipe(to) < 0) {
1496 		error("ssh_keysign: pipe: %s", strerror(errno));
1497 		return -1;
1498 	}
1499 	if (pipe(from) < 0) {
1500 		error("ssh_keysign: pipe: %s", strerror(errno));
1501 		return -1;
1502 	}
1503 	if ((pid = fork()) < 0) {
1504 		error("ssh_keysign: fork: %s", strerror(errno));
1505 		return -1;
1506 	}
1507 	if (pid == 0) {
1508 		permanently_drop_suid(getuid());
1509 		close(from[0]);
1510 		if (dup2(from[1], STDOUT_FILENO) < 0)
1511 			fatal("ssh_keysign: dup2: %s", strerror(errno));
1512 		close(to[1]);
1513 		if (dup2(to[0], STDIN_FILENO) < 0)
1514 			fatal("ssh_keysign: dup2: %s", strerror(errno));
1515 		close(from[1]);
1516 		close(to[0]);
1517 		execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1518 		fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1519 		    strerror(errno));
1520 	}
1521 	close(from[1]);
1522 	close(to[0]);
1523 
1524 	buffer_init(&b);
1525 	buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1526 	buffer_put_string(&b, data, datalen);
1527 	if (ssh_msg_send(to[1], version, &b) == -1)
1528 		fatal("ssh_keysign: couldn't send request");
1529 
1530 	if (ssh_msg_recv(from[0], &b) < 0) {
1531 		error("ssh_keysign: no reply");
1532 		buffer_free(&b);
1533 		return -1;
1534 	}
1535 	close(from[0]);
1536 	close(to[1]);
1537 
1538 	while (waitpid(pid, &status, 0) < 0)
1539 		if (errno != EINTR)
1540 			break;
1541 
1542 	if (buffer_get_char(&b) != version) {
1543 		error("ssh_keysign: bad version");
1544 		buffer_free(&b);
1545 		return -1;
1546 	}
1547 	*sigp = buffer_get_string(&b, lenp);
1548 	buffer_free(&b);
1549 
1550 	return 0;
1551 }
1552 
1553 int
1554 userauth_hostbased(Authctxt *authctxt)
1555 {
1556 	Key *private = NULL;
1557 	Sensitive *sensitive = authctxt->sensitive;
1558 	Buffer b;
1559 	u_char *signature, *blob;
1560 	char *chost, *pkalg, *p, myname[NI_MAXHOST];
1561 	const char *service;
1562 	u_int blen, slen;
1563 	int ok, i, len, found = 0;
1564 
1565 	/* check for a useful key */
1566 	for (i = 0; i < sensitive->nkeys; i++) {
1567 		private = sensitive->keys[i];
1568 		if (private && private->type != KEY_RSA1) {
1569 			found = 1;
1570 			/* we take and free the key */
1571 			sensitive->keys[i] = NULL;
1572 			break;
1573 		}
1574 	}
1575 	if (!found) {
1576 		debug("No more client hostkeys for hostbased authentication.");
1577 		return 0;
1578 	}
1579 	if (key_to_blob(private, &blob, &blen) == 0) {
1580 		key_free(private);
1581 		return 0;
1582 	}
1583 	/* figure out a name for the client host */
1584 	p = NULL;
1585 	if (packet_connection_is_on_socket())
1586 		p = get_local_name(packet_get_connection_in());
1587 	if (p == NULL) {
1588 		if (gethostname(myname, sizeof(myname)) == -1) {
1589 			verbose("userauth_hostbased: gethostname: %s",
1590 			    strerror(errno));
1591 		} else
1592 			p = xstrdup(myname);
1593 	}
1594 	if (p == NULL) {
1595 		error("userauth_hostbased: cannot get local ipaddr/name");
1596 		key_free(private);
1597 		xfree(blob);
1598 		return 0;
1599 	}
1600 	len = strlen(p) + 2;
1601 	xasprintf(&chost, "%s.", p);
1602 	debug2("userauth_hostbased: chost %s", chost);
1603 	xfree(p);
1604 
1605 	service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1606 	    authctxt->service;
1607 	pkalg = xstrdup(key_ssh_name(private));
1608 	buffer_init(&b);
1609 	/* construct data */
1610 	buffer_put_string(&b, session_id2, session_id2_len);
1611 	buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1612 	buffer_put_cstring(&b, authctxt->server_user);
1613 	buffer_put_cstring(&b, service);
1614 	buffer_put_cstring(&b, authctxt->method->name);
1615 	buffer_put_cstring(&b, pkalg);
1616 	buffer_put_string(&b, blob, blen);
1617 	buffer_put_cstring(&b, chost);
1618 	buffer_put_cstring(&b, authctxt->local_user);
1619 #ifdef DEBUG_PK
1620 	buffer_dump(&b);
1621 #endif
1622 	if (sensitive->external_keysign)
1623 		ok = ssh_keysign(private, &signature, &slen,
1624 		    buffer_ptr(&b), buffer_len(&b));
1625 	else
1626 		ok = key_sign(private, &signature, &slen,
1627 		    buffer_ptr(&b), buffer_len(&b));
1628 	key_free(private);
1629 	buffer_free(&b);
1630 	if (ok != 0) {
1631 		error("key_sign failed");
1632 		xfree(chost);
1633 		xfree(pkalg);
1634 		xfree(blob);
1635 		return 0;
1636 	}
1637 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
1638 	packet_put_cstring(authctxt->server_user);
1639 	packet_put_cstring(authctxt->service);
1640 	packet_put_cstring(authctxt->method->name);
1641 	packet_put_cstring(pkalg);
1642 	packet_put_string(blob, blen);
1643 	packet_put_cstring(chost);
1644 	packet_put_cstring(authctxt->local_user);
1645 	packet_put_string(signature, slen);
1646 	memset(signature, 's', slen);
1647 	xfree(signature);
1648 	xfree(chost);
1649 	xfree(pkalg);
1650 	xfree(blob);
1651 
1652 	packet_send();
1653 	return 1;
1654 }
1655 
1656 #ifdef JPAKE
1657 int
1658 userauth_jpake(Authctxt *authctxt)
1659 {
1660 	struct jpake_ctx *pctx;
1661 	u_char *x1_proof, *x2_proof;
1662 	u_int x1_proof_len, x2_proof_len;
1663 	static int attempt = 0; /* XXX share with userauth_password's? */
1664 
1665 	if (attempt++ >= options.number_of_password_prompts)
1666 		return 0;
1667 	if (attempt != 1)
1668 		error("Permission denied, please try again.");
1669 
1670 	if (authctxt->methoddata != NULL)
1671 		fatal("%s: authctxt->methoddata already set (%p)",
1672 		    __func__, authctxt->methoddata);
1673 
1674 	authctxt->methoddata = pctx = jpake_new();
1675 
1676 	/*
1677 	 * Send request immediately, to get the protocol going while
1678 	 * we do the initial computations.
1679 	 */
1680 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
1681 	packet_put_cstring(authctxt->server_user);
1682 	packet_put_cstring(authctxt->service);
1683 	packet_put_cstring(authctxt->method->name);
1684 	packet_send();
1685 	packet_write_wait();
1686 
1687 	jpake_step1(pctx->grp,
1688 	    &pctx->client_id, &pctx->client_id_len,
1689 	    &pctx->x1, &pctx->x2, &pctx->g_x1, &pctx->g_x2,
1690 	    &x1_proof, &x1_proof_len,
1691 	    &x2_proof, &x2_proof_len);
1692 
1693 	JPAKE_DEBUG_CTX((pctx, "step 1 sending in %s", __func__));
1694 
1695 	packet_start(SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1);
1696 	packet_put_string(pctx->client_id, pctx->client_id_len);
1697 	packet_put_bignum2(pctx->g_x1);
1698 	packet_put_bignum2(pctx->g_x2);
1699 	packet_put_string(x1_proof, x1_proof_len);
1700 	packet_put_string(x2_proof, x2_proof_len);
1701 	packet_send();
1702 
1703 	bzero(x1_proof, x1_proof_len);
1704 	bzero(x2_proof, x2_proof_len);
1705 	xfree(x1_proof);
1706 	xfree(x2_proof);
1707 
1708 	/* Expect step 1 packet from peer */
1709 	dispatch_set(SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1,
1710 	    input_userauth_jpake_server_step1);
1711 
1712 	return 1;
1713 }
1714 
1715 void
1716 userauth_jpake_cleanup(Authctxt *authctxt)
1717 {
1718 	debug3("%s: clean up", __func__);
1719 	if (authctxt->methoddata != NULL) {
1720 		jpake_free(authctxt->methoddata);
1721 		authctxt->methoddata = NULL;
1722 	}
1723 }
1724 #endif /* JPAKE */
1725 
1726 /* find auth method */
1727 
1728 /*
1729  * given auth method name, if configurable options permit this method fill
1730  * in auth_ident field and return true, otherwise return false.
1731  */
1732 static int
1733 authmethod_is_enabled(Authmethod *method)
1734 {
1735 	if (method == NULL)
1736 		return 0;
1737 	/* return false if options indicate this method is disabled */
1738 	if  (method->enabled == NULL || *method->enabled == 0)
1739 		return 0;
1740 	/* return false if batch mode is enabled but method needs interactive mode */
1741 	if  (method->batch_flag != NULL && *method->batch_flag != 0)
1742 		return 0;
1743 	return 1;
1744 }
1745 
1746 static Authmethod *
1747 authmethod_lookup(const char *name)
1748 {
1749 	Authmethod *method = NULL;
1750 	if (name != NULL)
1751 		for (method = authmethods; method->name != NULL; method++)
1752 			if (strcmp(name, method->name) == 0)
1753 				return method;
1754 	debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1755 	return NULL;
1756 }
1757 
1758 /* XXX internal state */
1759 static Authmethod *current = NULL;
1760 static char *supported = NULL;
1761 static char *preferred = NULL;
1762 
1763 /*
1764  * Given the authentication method list sent by the server, return the
1765  * next method we should try.  If the server initially sends a nil list,
1766  * use a built-in default list.
1767  */
1768 static Authmethod *
1769 authmethod_get(char *authlist)
1770 {
1771 	char *name = NULL;
1772 	u_int next;
1773 
1774 	/* Use a suitable default if we're passed a nil list.  */
1775 	if (authlist == NULL || strlen(authlist) == 0)
1776 		authlist = options.preferred_authentications;
1777 
1778 	if (supported == NULL || strcmp(authlist, supported) != 0) {
1779 		debug3("start over, passed a different list %s", authlist);
1780 		if (supported != NULL)
1781 			xfree(supported);
1782 		supported = xstrdup(authlist);
1783 		preferred = options.preferred_authentications;
1784 		debug3("preferred %s", preferred);
1785 		current = NULL;
1786 	} else if (current != NULL && authmethod_is_enabled(current))
1787 		return current;
1788 
1789 	for (;;) {
1790 		if ((name = match_list(preferred, supported, &next)) == NULL) {
1791 			debug("No more authentication methods to try.");
1792 			current = NULL;
1793 			return NULL;
1794 		}
1795 		preferred += next;
1796 		debug3("authmethod_lookup %s", name);
1797 		debug3("remaining preferred: %s", preferred);
1798 		if ((current = authmethod_lookup(name)) != NULL &&
1799 		    authmethod_is_enabled(current)) {
1800 			debug3("authmethod_is_enabled %s", name);
1801 			debug("Next authentication method: %s", name);
1802 			return current;
1803 		}
1804 	}
1805 }
1806 
1807 static char *
1808 authmethods_get(void)
1809 {
1810 	Authmethod *method = NULL;
1811 	Buffer b;
1812 	char *list;
1813 
1814 	buffer_init(&b);
1815 	for (method = authmethods; method->name != NULL; method++) {
1816 		if (authmethod_is_enabled(method)) {
1817 			if (buffer_len(&b) > 0)
1818 				buffer_append(&b, ",", 1);
1819 			buffer_append(&b, method->name, strlen(method->name));
1820 		}
1821 	}
1822 	buffer_append(&b, "\0", 1);
1823 	list = xstrdup(buffer_ptr(&b));
1824 	buffer_free(&b);
1825 	return list;
1826 }
1827 
1828