xref: /freebsd/crypto/openssh/sshconnect2.c (revision 4f52dfbb8d6c4d446500c5b097e3806ec219fbd4)
1 /* $OpenBSD: sshconnect2.c,v 1.266 2017/08/27 00:38:41 dtucker 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 <fcntl.h>
36 #include <netdb.h>
37 #include <pwd.h>
38 #include <signal.h>
39 #include <stdarg.h>
40 #include <stdio.h>
41 #include <string.h>
42 #include <unistd.h>
43 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
44 #include <vis.h>
45 #endif
46 
47 #include "openbsd-compat/sys-queue.h"
48 
49 #include "xmalloc.h"
50 #include "ssh.h"
51 #include "ssh2.h"
52 #include "buffer.h"
53 #include "packet.h"
54 #include "compat.h"
55 #include "cipher.h"
56 #include "key.h"
57 #include "kex.h"
58 #include "myproposal.h"
59 #include "sshconnect.h"
60 #include "authfile.h"
61 #include "dh.h"
62 #include "authfd.h"
63 #include "log.h"
64 #include "misc.h"
65 #include "readconf.h"
66 #include "match.h"
67 #include "dispatch.h"
68 #include "canohost.h"
69 #include "msg.h"
70 #include "pathnames.h"
71 #include "uidswap.h"
72 #include "hostfile.h"
73 #include "ssherr.h"
74 #include "utf8.h"
75 
76 #ifdef GSSAPI
77 #include "ssh-gss.h"
78 #endif
79 
80 /* import */
81 extern char *client_version_string;
82 extern char *server_version_string;
83 extern Options options;
84 
85 /*
86  * SSH2 key exchange
87  */
88 
89 u_char *session_id2 = NULL;
90 u_int session_id2_len = 0;
91 
92 char *xxx_host;
93 struct sockaddr *xxx_hostaddr;
94 
95 static int
96 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh)
97 {
98 	if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
99 		fatal("Host key verification failed.");
100 	return 0;
101 }
102 
103 static char *
104 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
105 {
106 	char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
107 	size_t maxlen;
108 	struct hostkeys *hostkeys;
109 	int ktype;
110 	u_int i;
111 
112 	/* Find all hostkeys for this hostname */
113 	get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
114 	hostkeys = init_hostkeys();
115 	for (i = 0; i < options.num_user_hostfiles; i++)
116 		load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
117 	for (i = 0; i < options.num_system_hostfiles; i++)
118 		load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
119 
120 	oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
121 	maxlen = strlen(avail) + 1;
122 	first = xmalloc(maxlen);
123 	last = xmalloc(maxlen);
124 	*first = *last = '\0';
125 
126 #define ALG_APPEND(to, from) \
127 	do { \
128 		if (*to != '\0') \
129 			strlcat(to, ",", maxlen); \
130 		strlcat(to, from, maxlen); \
131 	} while (0)
132 
133 	while ((alg = strsep(&avail, ",")) && *alg != '\0') {
134 		if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
135 			fatal("%s: unknown alg %s", __func__, alg);
136 		if (lookup_key_in_hostkeys_by_type(hostkeys,
137 		    sshkey_type_plain(ktype), NULL))
138 			ALG_APPEND(first, alg);
139 		else
140 			ALG_APPEND(last, alg);
141 	}
142 #undef ALG_APPEND
143 	xasprintf(&ret, "%s%s%s", first,
144 	    (*first == '\0' || *last == '\0') ? "" : ",", last);
145 	if (*first != '\0')
146 		debug3("%s: prefer hostkeyalgs: %s", __func__, first);
147 
148 	free(first);
149 	free(last);
150 	free(hostname);
151 	free(oavail);
152 	free_hostkeys(hostkeys);
153 
154 	return ret;
155 }
156 
157 void
158 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
159 {
160 	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
161 	char *s;
162 	struct kex *kex;
163 	int r;
164 
165 	xxx_host = host;
166 	xxx_hostaddr = hostaddr;
167 
168 	if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL)
169 		fatal("%s: kex_names_cat", __func__);
170 	myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s);
171 	myproposal[PROPOSAL_ENC_ALGS_CTOS] =
172 	    compat_cipher_proposal(options.ciphers);
173 	myproposal[PROPOSAL_ENC_ALGS_STOC] =
174 	    compat_cipher_proposal(options.ciphers);
175 	myproposal[PROPOSAL_COMP_ALGS_CTOS] =
176 	    myproposal[PROPOSAL_COMP_ALGS_STOC] = options.compression ?
177 	    "zlib@openssh.com,zlib,none" : "none,zlib@openssh.com,zlib";
178 	myproposal[PROPOSAL_MAC_ALGS_CTOS] =
179 	    myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
180 	if (options.hostkeyalgorithms != NULL) {
181 		if (kex_assemble_names(KEX_DEFAULT_PK_ALG,
182 		    &options.hostkeyalgorithms) != 0)
183 			fatal("%s: kex_assemble_namelist", __func__);
184 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
185 		    compat_pkalg_proposal(options.hostkeyalgorithms);
186 	} else {
187 		/* Enforce default */
188 		options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG);
189 		/* Prefer algorithms that we already have keys for */
190 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
191 		    compat_pkalg_proposal(
192 		    order_hostkeyalgs(host, hostaddr, port));
193 	}
194 
195 	if (options.rekey_limit || options.rekey_interval)
196 		packet_set_rekey_limits(options.rekey_limit,
197 		    options.rekey_interval);
198 
199 	/* start key exchange */
200 	if ((r = kex_setup(active_state, myproposal)) != 0)
201 		fatal("kex_setup: %s", ssh_err(r));
202 	kex = active_state->kex;
203 #ifdef WITH_OPENSSL
204 	kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
205 	kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
206 	kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client;
207 	kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client;
208 	kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client;
209 	kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
210 	kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
211 # ifdef OPENSSL_HAS_ECC
212 	kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
213 # endif
214 #endif
215 	kex->kex[KEX_C25519_SHA256] = kexc25519_client;
216 	kex->client_version_string=client_version_string;
217 	kex->server_version_string=server_version_string;
218 	kex->verify_host_key=&verify_host_key_callback;
219 
220 	ssh_dispatch_run_fatal(active_state, DISPATCH_BLOCK, &kex->done);
221 
222 	/* remove ext-info from the KEX proposals for rekeying */
223 	myproposal[PROPOSAL_KEX_ALGS] =
224 	    compat_kex_proposal(options.kex_algorithms);
225 	if ((r = kex_prop2buf(kex->my, myproposal)) != 0)
226 		fatal("kex_prop2buf: %s", ssh_err(r));
227 
228 	session_id2 = kex->session_id;
229 	session_id2_len = kex->session_id_len;
230 
231 #ifdef DEBUG_KEXDH
232 	/* send 1st encrypted/maced/compressed message */
233 	packet_start(SSH2_MSG_IGNORE);
234 	packet_put_cstring("markus");
235 	packet_send();
236 	packet_write_wait();
237 #endif
238 }
239 
240 /*
241  * Authenticate user
242  */
243 
244 typedef struct cauthctxt Authctxt;
245 typedef struct cauthmethod Authmethod;
246 typedef struct identity Identity;
247 typedef struct idlist Idlist;
248 
249 struct identity {
250 	TAILQ_ENTRY(identity) next;
251 	int	agent_fd;		/* >=0 if agent supports key */
252 	struct sshkey	*key;		/* public/private key */
253 	char	*filename;		/* comment for agent-only keys */
254 	int	tried;
255 	int	isprivate;		/* key points to the private key */
256 	int	userprovided;
257 };
258 TAILQ_HEAD(idlist, identity);
259 
260 struct cauthctxt {
261 	const char *server_user;
262 	const char *local_user;
263 	const char *host;
264 	const char *service;
265 	struct cauthmethod *method;
266 	sig_atomic_t success;
267 	char *authlist;
268 	int attempt;
269 	/* pubkey */
270 	struct idlist keys;
271 	int agent_fd;
272 	/* hostbased */
273 	Sensitive *sensitive;
274 	char *oktypes, *ktypes;
275 	const char *active_ktype;
276 	/* kbd-interactive */
277 	int info_req_seen;
278 	/* generic */
279 	void *methoddata;
280 };
281 
282 struct cauthmethod {
283 	char	*name;		/* string to compare against server's list */
284 	int	(*userauth)(Authctxt *authctxt);
285 	void	(*cleanup)(Authctxt *authctxt);
286 	int	*enabled;	/* flag in option struct that enables method */
287 	int	*batch_flag;	/* flag in option struct that disables method */
288 };
289 
290 int	input_userauth_service_accept(int, u_int32_t, struct ssh *);
291 int	input_userauth_ext_info(int, u_int32_t, struct ssh *);
292 int	input_userauth_success(int, u_int32_t, struct ssh *);
293 int	input_userauth_success_unexpected(int, u_int32_t, struct ssh *);
294 int	input_userauth_failure(int, u_int32_t, struct ssh *);
295 int	input_userauth_banner(int, u_int32_t, struct ssh *);
296 int	input_userauth_error(int, u_int32_t, struct ssh *);
297 int	input_userauth_info_req(int, u_int32_t, struct ssh *);
298 int	input_userauth_pk_ok(int, u_int32_t, struct ssh *);
299 int	input_userauth_passwd_changereq(int, u_int32_t, struct ssh *);
300 
301 int	userauth_none(Authctxt *);
302 int	userauth_pubkey(Authctxt *);
303 int	userauth_passwd(Authctxt *);
304 int	userauth_kbdint(Authctxt *);
305 int	userauth_hostbased(Authctxt *);
306 
307 #ifdef GSSAPI
308 int	userauth_gssapi(Authctxt *authctxt);
309 int	input_gssapi_response(int type, u_int32_t, struct ssh *);
310 int	input_gssapi_token(int type, u_int32_t, struct ssh *);
311 int	input_gssapi_hash(int type, u_int32_t, struct ssh *);
312 int	input_gssapi_error(int, u_int32_t, struct ssh *);
313 int	input_gssapi_errtok(int, u_int32_t, struct ssh *);
314 #endif
315 
316 void	userauth(Authctxt *, char *);
317 
318 static int sign_and_send_pubkey(Authctxt *, Identity *);
319 static void pubkey_prepare(Authctxt *);
320 static void pubkey_cleanup(Authctxt *);
321 static void pubkey_reset(Authctxt *);
322 static struct sshkey *load_identity_file(Identity *);
323 
324 static Authmethod *authmethod_get(char *authlist);
325 static Authmethod *authmethod_lookup(const char *name);
326 static char *authmethods_get(void);
327 
328 Authmethod authmethods[] = {
329 #ifdef GSSAPI
330 	{"gssapi-with-mic",
331 		userauth_gssapi,
332 		NULL,
333 		&options.gss_authentication,
334 		NULL},
335 #endif
336 	{"hostbased",
337 		userauth_hostbased,
338 		NULL,
339 		&options.hostbased_authentication,
340 		NULL},
341 	{"publickey",
342 		userauth_pubkey,
343 		NULL,
344 		&options.pubkey_authentication,
345 		NULL},
346 	{"keyboard-interactive",
347 		userauth_kbdint,
348 		NULL,
349 		&options.kbd_interactive_authentication,
350 		&options.batch_mode},
351 	{"password",
352 		userauth_passwd,
353 		NULL,
354 		&options.password_authentication,
355 		&options.batch_mode},
356 	{"none",
357 		userauth_none,
358 		NULL,
359 		NULL,
360 		NULL},
361 	{NULL, NULL, NULL, NULL, NULL}
362 };
363 
364 void
365 ssh_userauth2(const char *local_user, const char *server_user, char *host,
366     Sensitive *sensitive)
367 {
368 	struct ssh *ssh = active_state;
369 	Authctxt authctxt;
370 	int r;
371 
372 	if (options.challenge_response_authentication)
373 		options.kbd_interactive_authentication = 1;
374 	if (options.preferred_authentications == NULL)
375 		options.preferred_authentications = authmethods_get();
376 
377 	/* setup authentication context */
378 	memset(&authctxt, 0, sizeof(authctxt));
379 	pubkey_prepare(&authctxt);
380 	authctxt.server_user = server_user;
381 	authctxt.local_user = local_user;
382 	authctxt.host = host;
383 	authctxt.service = "ssh-connection";		/* service name */
384 	authctxt.success = 0;
385 	authctxt.method = authmethod_lookup("none");
386 	authctxt.authlist = NULL;
387 	authctxt.methoddata = NULL;
388 	authctxt.sensitive = sensitive;
389 	authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL;
390 	authctxt.info_req_seen = 0;
391 	authctxt.agent_fd = -1;
392 	if (authctxt.method == NULL)
393 		fatal("ssh_userauth2: internal error: cannot send userauth none request");
394 
395 	if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 ||
396 	    (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 ||
397 	    (r = sshpkt_send(ssh)) != 0)
398 		fatal("%s: %s", __func__, ssh_err(r));
399 
400 	ssh->authctxt = &authctxt;
401 	ssh_dispatch_init(ssh, &input_userauth_error);
402 	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info);
403 	ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept);
404 	ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success);	/* loop until success */
405 	ssh->authctxt = NULL;
406 
407 	pubkey_cleanup(&authctxt);
408 	ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
409 
410 	if (!authctxt.success)
411 		fatal("Authentication failed.");
412 	debug("Authentication succeeded (%s).", authctxt.method->name);
413 }
414 
415 /* ARGSUSED */
416 int
417 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh)
418 {
419 	Authctxt *authctxt = ssh->authctxt;
420 	int r;
421 
422 	if (ssh_packet_remaining(ssh) > 0) {
423 		char *reply;
424 
425 		if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0)
426 			goto out;
427 		debug2("service_accept: %s", reply);
428 		free(reply);
429 	} else {
430 		debug2("buggy server: service_accept w/o service");
431 	}
432 	if ((r = sshpkt_get_end(ssh)) != 0)
433 		goto out;
434 	debug("SSH2_MSG_SERVICE_ACCEPT received");
435 
436 	/* initial userauth request */
437 	userauth_none(authctxt);
438 
439 	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error);
440 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
441 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
442 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
443 	r = 0;
444  out:
445 	return r;
446 }
447 
448 /* ARGSUSED */
449 int
450 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh)
451 {
452 	return kex_input_ext_info(type, seqnr, ssh);
453 }
454 
455 void
456 userauth(Authctxt *authctxt, char *authlist)
457 {
458 	if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
459 		authctxt->method->cleanup(authctxt);
460 
461 	free(authctxt->methoddata);
462 	authctxt->methoddata = NULL;
463 	if (authlist == NULL) {
464 		authlist = authctxt->authlist;
465 	} else {
466 		free(authctxt->authlist);
467 		authctxt->authlist = authlist;
468 	}
469 	for (;;) {
470 		Authmethod *method = authmethod_get(authlist);
471 		if (method == NULL)
472 			fatal("%s@%s: Permission denied (%s).",
473 			    authctxt->server_user, authctxt->host, authlist);
474 		authctxt->method = method;
475 
476 		/* reset the per method handler */
477 		dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
478 		    SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
479 
480 		/* and try new method */
481 		if (method->userauth(authctxt) != 0) {
482 			debug2("we sent a %s packet, wait for reply", method->name);
483 			break;
484 		} else {
485 			debug2("we did not send a packet, disable method");
486 			method->enabled = NULL;
487 		}
488 	}
489 }
490 
491 /* ARGSUSED */
492 int
493 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh)
494 {
495 	fatal("input_userauth_error: bad message during authentication: "
496 	    "type %d", type);
497 	return 0;
498 }
499 
500 /* ARGSUSED */
501 int
502 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh)
503 {
504 	char *msg, *lang;
505 	u_int len;
506 
507 	debug3("%s", __func__);
508 	msg = packet_get_string(&len);
509 	lang = packet_get_string(NULL);
510 	if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO)
511 		fmprintf(stderr, "%s", msg);
512 	free(msg);
513 	free(lang);
514 	return 0;
515 }
516 
517 /* ARGSUSED */
518 int
519 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh)
520 {
521 	Authctxt *authctxt = ssh->authctxt;
522 
523 	if (authctxt == NULL)
524 		fatal("input_userauth_success: no authentication context");
525 	free(authctxt->authlist);
526 	authctxt->authlist = NULL;
527 	if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
528 		authctxt->method->cleanup(authctxt);
529 	free(authctxt->methoddata);
530 	authctxt->methoddata = NULL;
531 	authctxt->success = 1;			/* break out */
532 	return 0;
533 }
534 
535 int
536 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh)
537 {
538 	Authctxt *authctxt = ssh->authctxt;
539 
540 	if (authctxt == NULL)
541 		fatal("%s: no authentication context", __func__);
542 
543 	fatal("Unexpected authentication success during %s.",
544 	    authctxt->method->name);
545 	return 0;
546 }
547 
548 /* ARGSUSED */
549 int
550 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh)
551 {
552 	Authctxt *authctxt = ssh->authctxt;
553 	char *authlist = NULL;
554 	int partial;
555 
556 	if (authctxt == NULL)
557 		fatal("input_userauth_failure: no authentication context");
558 
559 	authlist = packet_get_string(NULL);
560 	partial = packet_get_char();
561 	packet_check_eom();
562 
563 	if (partial != 0) {
564 		verbose("Authenticated with partial success.");
565 		/* reset state */
566 		pubkey_reset(authctxt);
567 	}
568 	debug("Authentications that can continue: %s", authlist);
569 
570 	userauth(authctxt, authlist);
571 	return 0;
572 }
573 
574 /* ARGSUSED */
575 int
576 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh)
577 {
578 	Authctxt *authctxt = ssh->authctxt;
579 	struct sshkey *key = NULL;
580 	Identity *id = NULL;
581 	Buffer b;
582 	int pktype, sent = 0;
583 	u_int alen, blen;
584 	char *pkalg, *fp;
585 	u_char *pkblob;
586 
587 	if (authctxt == NULL)
588 		fatal("input_userauth_pk_ok: no authentication context");
589 	if (datafellows & SSH_BUG_PKOK) {
590 		/* this is similar to SSH_BUG_PKAUTH */
591 		debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
592 		pkblob = packet_get_string(&blen);
593 		buffer_init(&b);
594 		buffer_append(&b, pkblob, blen);
595 		pkalg = buffer_get_string(&b, &alen);
596 		buffer_free(&b);
597 	} else {
598 		pkalg = packet_get_string(&alen);
599 		pkblob = packet_get_string(&blen);
600 	}
601 	packet_check_eom();
602 
603 	debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
604 
605 	if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
606 		debug("unknown pkalg %s", pkalg);
607 		goto done;
608 	}
609 	if ((key = key_from_blob(pkblob, blen)) == NULL) {
610 		debug("no key from blob. pkalg %s", pkalg);
611 		goto done;
612 	}
613 	if (key->type != pktype) {
614 		error("input_userauth_pk_ok: type mismatch "
615 		    "for decoded key (received %d, expected %d)",
616 		    key->type, pktype);
617 		goto done;
618 	}
619 	if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
620 	    SSH_FP_DEFAULT)) == NULL)
621 		goto done;
622 	debug2("input_userauth_pk_ok: fp %s", fp);
623 	free(fp);
624 
625 	/*
626 	 * search keys in the reverse order, because last candidate has been
627 	 * moved to the end of the queue.  this also avoids confusion by
628 	 * duplicate keys
629 	 */
630 	TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
631 		if (key_equal(key, id->key)) {
632 			sent = sign_and_send_pubkey(authctxt, id);
633 			break;
634 		}
635 	}
636 done:
637 	if (key != NULL)
638 		key_free(key);
639 	free(pkalg);
640 	free(pkblob);
641 
642 	/* try another method if we did not send a packet */
643 	if (sent == 0)
644 		userauth(authctxt, NULL);
645 	return 0;
646 }
647 
648 #ifdef GSSAPI
649 int
650 userauth_gssapi(Authctxt *authctxt)
651 {
652 	Gssctxt *gssctxt = NULL;
653 	static gss_OID_set gss_supported = NULL;
654 	static u_int mech = 0;
655 	OM_uint32 min;
656 	int ok = 0;
657 
658 	/* Try one GSSAPI method at a time, rather than sending them all at
659 	 * once. */
660 
661 	if (gss_supported == NULL)
662 		gss_indicate_mechs(&min, &gss_supported);
663 
664 	/* Check to see if the mechanism is usable before we offer it */
665 	while (mech < gss_supported->count && !ok) {
666 		/* My DER encoding requires length<128 */
667 		if (gss_supported->elements[mech].length < 128 &&
668 		    ssh_gssapi_check_mechanism(&gssctxt,
669 		    &gss_supported->elements[mech], authctxt->host)) {
670 			ok = 1; /* Mechanism works */
671 		} else {
672 			mech++;
673 		}
674 	}
675 
676 	if (!ok)
677 		return 0;
678 
679 	authctxt->methoddata=(void *)gssctxt;
680 
681 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
682 	packet_put_cstring(authctxt->server_user);
683 	packet_put_cstring(authctxt->service);
684 	packet_put_cstring(authctxt->method->name);
685 
686 	packet_put_int(1);
687 
688 	packet_put_int((gss_supported->elements[mech].length) + 2);
689 	packet_put_char(SSH_GSS_OIDTYPE);
690 	packet_put_char(gss_supported->elements[mech].length);
691 	packet_put_raw(gss_supported->elements[mech].elements,
692 	    gss_supported->elements[mech].length);
693 
694 	packet_send();
695 
696 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
697 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
698 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
699 	dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
700 
701 	mech++; /* Move along to next candidate */
702 
703 	return 1;
704 }
705 
706 static OM_uint32
707 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok)
708 {
709 	Authctxt *authctxt = ssh->authctxt;
710 	Gssctxt *gssctxt = authctxt->methoddata;
711 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
712 	gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
713 	gss_buffer_desc gssbuf;
714 	OM_uint32 status, ms, flags;
715 	Buffer b;
716 
717 	status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
718 	    recv_tok, &send_tok, &flags);
719 
720 	if (send_tok.length > 0) {
721 		if (GSS_ERROR(status))
722 			packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
723 		else
724 			packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
725 
726 		packet_put_string(send_tok.value, send_tok.length);
727 		packet_send();
728 		gss_release_buffer(&ms, &send_tok);
729 	}
730 
731 	if (status == GSS_S_COMPLETE) {
732 		/* send either complete or MIC, depending on mechanism */
733 		if (!(flags & GSS_C_INTEG_FLAG)) {
734 			packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
735 			packet_send();
736 		} else {
737 			ssh_gssapi_buildmic(&b, authctxt->server_user,
738 			    authctxt->service, "gssapi-with-mic");
739 
740 			gssbuf.value = buffer_ptr(&b);
741 			gssbuf.length = buffer_len(&b);
742 
743 			status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
744 
745 			if (!GSS_ERROR(status)) {
746 				packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
747 				packet_put_string(mic.value, mic.length);
748 
749 				packet_send();
750 			}
751 
752 			buffer_free(&b);
753 			gss_release_buffer(&ms, &mic);
754 		}
755 	}
756 
757 	return status;
758 }
759 
760 /* ARGSUSED */
761 int
762 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh)
763 {
764 	Authctxt *authctxt = ssh->authctxt;
765 	Gssctxt *gssctxt;
766 	int oidlen;
767 	char *oidv;
768 
769 	if (authctxt == NULL)
770 		fatal("input_gssapi_response: no authentication context");
771 	gssctxt = authctxt->methoddata;
772 
773 	/* Setup our OID */
774 	oidv = packet_get_string(&oidlen);
775 
776 	if (oidlen <= 2 ||
777 	    oidv[0] != SSH_GSS_OIDTYPE ||
778 	    oidv[1] != oidlen - 2) {
779 		free(oidv);
780 		debug("Badly encoded mechanism OID received");
781 		userauth(authctxt, NULL);
782 		return 0;
783 	}
784 
785 	if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
786 		fatal("Server returned different OID than expected");
787 
788 	packet_check_eom();
789 
790 	free(oidv);
791 
792 	if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) {
793 		/* Start again with next method on list */
794 		debug("Trying to start again");
795 		userauth(authctxt, NULL);
796 		return 0;
797 	}
798 	return 0;
799 }
800 
801 /* ARGSUSED */
802 int
803 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh)
804 {
805 	Authctxt *authctxt = ssh->authctxt;
806 	gss_buffer_desc recv_tok;
807 	OM_uint32 status;
808 	u_int slen;
809 
810 	if (authctxt == NULL)
811 		fatal("input_gssapi_response: no authentication context");
812 
813 	recv_tok.value = packet_get_string(&slen);
814 	recv_tok.length = slen;	/* safe typecast */
815 
816 	packet_check_eom();
817 
818 	status = process_gssapi_token(ssh, &recv_tok);
819 
820 	free(recv_tok.value);
821 
822 	if (GSS_ERROR(status)) {
823 		/* Start again with the next method in the list */
824 		userauth(authctxt, NULL);
825 		return 0;
826 	}
827 	return 0;
828 }
829 
830 /* ARGSUSED */
831 int
832 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh)
833 {
834 	Authctxt *authctxt = ssh->authctxt;
835 	Gssctxt *gssctxt;
836 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
837 	gss_buffer_desc recv_tok;
838 	OM_uint32 ms;
839 	u_int len;
840 
841 	if (authctxt == NULL)
842 		fatal("input_gssapi_response: no authentication context");
843 	gssctxt = authctxt->methoddata;
844 
845 	recv_tok.value = packet_get_string(&len);
846 	recv_tok.length = len;
847 
848 	packet_check_eom();
849 
850 	/* Stick it into GSSAPI and see what it says */
851 	(void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
852 	    &recv_tok, &send_tok, NULL);
853 
854 	free(recv_tok.value);
855 	gss_release_buffer(&ms, &send_tok);
856 
857 	/* Server will be returning a failed packet after this one */
858 	return 0;
859 }
860 
861 /* ARGSUSED */
862 int
863 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
864 {
865 	char *msg;
866 	char *lang;
867 
868 	/* maj */(void)packet_get_int();
869 	/* min */(void)packet_get_int();
870 	msg=packet_get_string(NULL);
871 	lang=packet_get_string(NULL);
872 
873 	packet_check_eom();
874 
875 	debug("Server GSSAPI Error:\n%s", msg);
876 	free(msg);
877 	free(lang);
878 	return 0;
879 }
880 #endif /* GSSAPI */
881 
882 int
883 userauth_none(Authctxt *authctxt)
884 {
885 	/* initial userauth request */
886 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
887 	packet_put_cstring(authctxt->server_user);
888 	packet_put_cstring(authctxt->service);
889 	packet_put_cstring(authctxt->method->name);
890 	packet_send();
891 	return 1;
892 }
893 
894 int
895 userauth_passwd(Authctxt *authctxt)
896 {
897 	static int attempt = 0;
898 	char prompt[256];
899 	char *password;
900 	const char *host = options.host_key_alias ?  options.host_key_alias :
901 	    authctxt->host;
902 
903 	if (attempt++ >= options.number_of_password_prompts)
904 		return 0;
905 
906 	if (attempt != 1)
907 		error("Permission denied, please try again.");
908 
909 	snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
910 	    authctxt->server_user, host);
911 	password = read_passphrase(prompt, 0);
912 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
913 	packet_put_cstring(authctxt->server_user);
914 	packet_put_cstring(authctxt->service);
915 	packet_put_cstring(authctxt->method->name);
916 	packet_put_char(0);
917 	packet_put_cstring(password);
918 	explicit_bzero(password, strlen(password));
919 	free(password);
920 	packet_add_padding(64);
921 	packet_send();
922 
923 	dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
924 	    &input_userauth_passwd_changereq);
925 
926 	return 1;
927 }
928 
929 /*
930  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
931  */
932 /* ARGSUSED */
933 int
934 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh)
935 {
936 	Authctxt *authctxt = ssh->authctxt;
937 	char *info, *lang, *password = NULL, *retype = NULL;
938 	char prompt[256];
939 	const char *host;
940 
941 	debug2("input_userauth_passwd_changereq");
942 
943 	if (authctxt == NULL)
944 		fatal("input_userauth_passwd_changereq: "
945 		    "no authentication context");
946 	host = options.host_key_alias ? options.host_key_alias : authctxt->host;
947 
948 	info = packet_get_string(NULL);
949 	lang = packet_get_string(NULL);
950 	if (strlen(info) > 0)
951 		logit("%s", info);
952 	free(info);
953 	free(lang);
954 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
955 	packet_put_cstring(authctxt->server_user);
956 	packet_put_cstring(authctxt->service);
957 	packet_put_cstring(authctxt->method->name);
958 	packet_put_char(1);			/* additional info */
959 	snprintf(prompt, sizeof(prompt),
960 	    "Enter %.30s@%.128s's old password: ",
961 	    authctxt->server_user, host);
962 	password = read_passphrase(prompt, 0);
963 	packet_put_cstring(password);
964 	explicit_bzero(password, strlen(password));
965 	free(password);
966 	password = NULL;
967 	while (password == NULL) {
968 		snprintf(prompt, sizeof(prompt),
969 		    "Enter %.30s@%.128s's new password: ",
970 		    authctxt->server_user, host);
971 		password = read_passphrase(prompt, RP_ALLOW_EOF);
972 		if (password == NULL) {
973 			/* bail out */
974 			return 0;
975 		}
976 		snprintf(prompt, sizeof(prompt),
977 		    "Retype %.30s@%.128s's new password: ",
978 		    authctxt->server_user, host);
979 		retype = read_passphrase(prompt, 0);
980 		if (strcmp(password, retype) != 0) {
981 			explicit_bzero(password, strlen(password));
982 			free(password);
983 			logit("Mismatch; try again, EOF to quit.");
984 			password = NULL;
985 		}
986 		explicit_bzero(retype, strlen(retype));
987 		free(retype);
988 	}
989 	packet_put_cstring(password);
990 	explicit_bzero(password, strlen(password));
991 	free(password);
992 	packet_add_padding(64);
993 	packet_send();
994 
995 	dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
996 	    &input_userauth_passwd_changereq);
997 	return 0;
998 }
999 
1000 static const char *
1001 key_sign_encode(const struct sshkey *key)
1002 {
1003 	struct ssh *ssh = active_state;
1004 
1005 	if (key->type == KEY_RSA) {
1006 		switch (ssh->kex->rsa_sha2) {
1007 		case 256:
1008 			return "rsa-sha2-256";
1009 		case 512:
1010 			return "rsa-sha2-512";
1011 		}
1012 	}
1013 	return key_ssh_name(key);
1014 }
1015 
1016 static int
1017 identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
1018     const u_char *data, size_t datalen, u_int compat)
1019 {
1020 	struct sshkey *prv;
1021 	int ret;
1022 
1023 	/* the agent supports this key */
1024 	if (id->key != NULL && id->agent_fd != -1)
1025 		return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp,
1026 		    data, datalen, key_sign_encode(id->key), compat);
1027 
1028 	/*
1029 	 * we have already loaded the private key or
1030 	 * the private key is stored in external hardware
1031 	 */
1032 	if (id->key != NULL &&
1033 	    (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT)))
1034 		return (sshkey_sign(id->key, sigp, lenp, data, datalen,
1035 		    key_sign_encode(id->key), compat));
1036 
1037 	/* load the private key from the file */
1038 	if ((prv = load_identity_file(id)) == NULL)
1039 		return SSH_ERR_KEY_NOT_FOUND;
1040 	if (id->key != NULL && !sshkey_equal_public(prv, id->key)) {
1041 		error("%s: private key %s contents do not match public",
1042 		   __func__, id->filename);
1043 		return SSH_ERR_KEY_NOT_FOUND;
1044 	}
1045 	ret = sshkey_sign(prv, sigp, lenp, data, datalen,
1046 	    key_sign_encode(prv), compat);
1047 	sshkey_free(prv);
1048 	return (ret);
1049 }
1050 
1051 static int
1052 id_filename_matches(Identity *id, Identity *private_id)
1053 {
1054 	const char *suffixes[] = { ".pub", "-cert.pub", NULL };
1055 	size_t len = strlen(id->filename), plen = strlen(private_id->filename);
1056 	size_t i, slen;
1057 
1058 	if (strcmp(id->filename, private_id->filename) == 0)
1059 		return 1;
1060 	for (i = 0; suffixes[i]; i++) {
1061 		slen = strlen(suffixes[i]);
1062 		if (len > slen && plen == len - slen &&
1063 		    strcmp(id->filename + (len - slen), suffixes[i]) == 0 &&
1064 		    memcmp(id->filename, private_id->filename, plen) == 0)
1065 			return 1;
1066 	}
1067 	return 0;
1068 }
1069 
1070 static int
1071 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1072 {
1073 	Buffer b;
1074 	Identity *private_id;
1075 	u_char *blob, *signature;
1076 	size_t slen;
1077 	u_int bloblen, skip = 0;
1078 	int matched, ret = -1, have_sig = 1;
1079 	char *fp;
1080 
1081 	if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
1082 	    SSH_FP_DEFAULT)) == NULL)
1083 		return 0;
1084 	debug3("%s: %s %s", __func__, key_type(id->key), fp);
1085 	free(fp);
1086 
1087 	if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1088 		/* we cannot handle this key */
1089 		debug3("sign_and_send_pubkey: cannot handle key");
1090 		return 0;
1091 	}
1092 	/* data to be signed */
1093 	buffer_init(&b);
1094 	if (datafellows & SSH_OLD_SESSIONID) {
1095 		buffer_append(&b, session_id2, session_id2_len);
1096 		skip = session_id2_len;
1097 	} else {
1098 		buffer_put_string(&b, session_id2, session_id2_len);
1099 		skip = buffer_len(&b);
1100 	}
1101 	buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1102 	buffer_put_cstring(&b, authctxt->server_user);
1103 	buffer_put_cstring(&b,
1104 	    datafellows & SSH_BUG_PKSERVICE ?
1105 	    "ssh-userauth" :
1106 	    authctxt->service);
1107 	if (datafellows & SSH_BUG_PKAUTH) {
1108 		buffer_put_char(&b, have_sig);
1109 	} else {
1110 		buffer_put_cstring(&b, authctxt->method->name);
1111 		buffer_put_char(&b, have_sig);
1112 		buffer_put_cstring(&b, key_sign_encode(id->key));
1113 	}
1114 	buffer_put_string(&b, blob, bloblen);
1115 
1116 	/*
1117 	 * If the key is an certificate, try to find a matching private key
1118 	 * and use it to complete the signature.
1119 	 * If no such private key exists, fall back to trying the certificate
1120 	 * key itself in case it has a private half already loaded.
1121 	 */
1122 	if (key_is_cert(id->key)) {
1123 		matched = 0;
1124 		TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1125 			if (sshkey_equal_public(id->key, private_id->key) &&
1126 			    id->key->type != private_id->key->type) {
1127 				id = private_id;
1128 				matched = 1;
1129 				break;
1130 			}
1131 		}
1132 		/*
1133 		 * Exact key matches are preferred, but also allow
1134 		 * filename matches for non-PKCS#11/agent keys that
1135 		 * didn't load public keys. This supports the case
1136 		 * of keeping just a private key file and public
1137 		 * certificate on disk.
1138 		 */
1139 		if (!matched && !id->isprivate && id->agent_fd == -1 &&
1140 		    (id->key->flags & SSHKEY_FLAG_EXT) == 0) {
1141 			TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1142 				if (private_id->key == NULL &&
1143 				    id_filename_matches(id, private_id)) {
1144 					id = private_id;
1145 					matched = 1;
1146 					break;
1147 				}
1148 			}
1149 		}
1150 		if (matched) {
1151 			debug2("%s: using private key \"%s\"%s for "
1152 			    "certificate", __func__, id->filename,
1153 			    id->agent_fd != -1 ? " from agent" : "");
1154 		} else {
1155 			debug("%s: no separate private key for certificate "
1156 			    "\"%s\"", __func__, id->filename);
1157 		}
1158 	}
1159 
1160 	/* generate signature */
1161 	ret = identity_sign(id, &signature, &slen,
1162 	    buffer_ptr(&b), buffer_len(&b), datafellows);
1163 	if (ret != 0) {
1164 		if (ret != SSH_ERR_KEY_NOT_FOUND)
1165 			error("%s: signing failed: %s", __func__, ssh_err(ret));
1166 		free(blob);
1167 		buffer_free(&b);
1168 		return 0;
1169 	}
1170 #ifdef DEBUG_PK
1171 	buffer_dump(&b);
1172 #endif
1173 	if (datafellows & SSH_BUG_PKSERVICE) {
1174 		buffer_clear(&b);
1175 		buffer_append(&b, session_id2, session_id2_len);
1176 		skip = session_id2_len;
1177 		buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1178 		buffer_put_cstring(&b, authctxt->server_user);
1179 		buffer_put_cstring(&b, authctxt->service);
1180 		buffer_put_cstring(&b, authctxt->method->name);
1181 		buffer_put_char(&b, have_sig);
1182 		if (!(datafellows & SSH_BUG_PKAUTH))
1183 			buffer_put_cstring(&b, key_ssh_name(id->key));
1184 		buffer_put_string(&b, blob, bloblen);
1185 	}
1186 	free(blob);
1187 
1188 	/* append signature */
1189 	buffer_put_string(&b, signature, slen);
1190 	free(signature);
1191 
1192 	/* skip session id and packet type */
1193 	if (buffer_len(&b) < skip + 1)
1194 		fatal("userauth_pubkey: internal error");
1195 	buffer_consume(&b, skip + 1);
1196 
1197 	/* put remaining data from buffer into packet */
1198 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
1199 	packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1200 	buffer_free(&b);
1201 	packet_send();
1202 
1203 	return 1;
1204 }
1205 
1206 static int
1207 send_pubkey_test(Authctxt *authctxt, Identity *id)
1208 {
1209 	u_char *blob;
1210 	u_int bloblen, have_sig = 0;
1211 
1212 	debug3("send_pubkey_test");
1213 
1214 	if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1215 		/* we cannot handle this key */
1216 		debug3("send_pubkey_test: cannot handle key");
1217 		return 0;
1218 	}
1219 	/* register callback for USERAUTH_PK_OK message */
1220 	dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1221 
1222 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
1223 	packet_put_cstring(authctxt->server_user);
1224 	packet_put_cstring(authctxt->service);
1225 	packet_put_cstring(authctxt->method->name);
1226 	packet_put_char(have_sig);
1227 	if (!(datafellows & SSH_BUG_PKAUTH))
1228 		packet_put_cstring(key_sign_encode(id->key));
1229 	packet_put_string(blob, bloblen);
1230 	free(blob);
1231 	packet_send();
1232 	return 1;
1233 }
1234 
1235 static struct sshkey *
1236 load_identity_file(Identity *id)
1237 {
1238 	struct sshkey *private = NULL;
1239 	char prompt[300], *passphrase, *comment;
1240 	int r, perm_ok = 0, quit = 0, i;
1241 	struct stat st;
1242 
1243 	if (stat(id->filename, &st) < 0) {
1244 		(id->userprovided ? logit : debug3)("no such identity: %s: %s",
1245 		    id->filename, strerror(errno));
1246 		return NULL;
1247 	}
1248 	snprintf(prompt, sizeof prompt,
1249 	    "Enter passphrase for key '%.100s': ", id->filename);
1250 	for (i = 0; i <= options.number_of_password_prompts; i++) {
1251 		if (i == 0)
1252 			passphrase = "";
1253 		else {
1254 			passphrase = read_passphrase(prompt, 0);
1255 			if (*passphrase == '\0') {
1256 				debug2("no passphrase given, try next key");
1257 				free(passphrase);
1258 				break;
1259 			}
1260 		}
1261 		switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename,
1262 		    passphrase, &private, &comment, &perm_ok))) {
1263 		case 0:
1264 			break;
1265 		case SSH_ERR_KEY_WRONG_PASSPHRASE:
1266 			if (options.batch_mode) {
1267 				quit = 1;
1268 				break;
1269 			}
1270 			if (i != 0)
1271 				debug2("bad passphrase given, try again...");
1272 			break;
1273 		case SSH_ERR_SYSTEM_ERROR:
1274 			if (errno == ENOENT) {
1275 				debug2("Load key \"%s\": %s",
1276 				    id->filename, ssh_err(r));
1277 				quit = 1;
1278 				break;
1279 			}
1280 			/* FALLTHROUGH */
1281 		default:
1282 			error("Load key \"%s\": %s", id->filename, ssh_err(r));
1283 			quit = 1;
1284 			break;
1285 		}
1286 		if (!quit && private != NULL && id->agent_fd == -1 &&
1287 		    !(id->key && id->isprivate))
1288 			maybe_add_key_to_agent(id->filename, private, comment,
1289 			    passphrase);
1290 		if (i > 0) {
1291 			explicit_bzero(passphrase, strlen(passphrase));
1292 			free(passphrase);
1293 		}
1294 		free(comment);
1295 		if (private != NULL || quit)
1296 			break;
1297 	}
1298 	return private;
1299 }
1300 
1301 /*
1302  * try keys in the following order:
1303  * 	1. certificates listed in the config file
1304  * 	2. other input certificates
1305  *	3. agent keys that are found in the config file
1306  *	4. other agent keys
1307  *	5. keys that are only listed in the config file
1308  */
1309 static void
1310 pubkey_prepare(Authctxt *authctxt)
1311 {
1312 	struct identity *id, *id2, *tmp;
1313 	struct idlist agent, files, *preferred;
1314 	struct sshkey *key;
1315 	int agent_fd = -1, i, r, found;
1316 	size_t j;
1317 	struct ssh_identitylist *idlist;
1318 
1319 	TAILQ_INIT(&agent);	/* keys from the agent */
1320 	TAILQ_INIT(&files);	/* keys from the config file */
1321 	preferred = &authctxt->keys;
1322 	TAILQ_INIT(preferred);	/* preferred order of keys */
1323 
1324 	/* list of keys stored in the filesystem and PKCS#11 */
1325 	for (i = 0; i < options.num_identity_files; i++) {
1326 		key = options.identity_keys[i];
1327 		if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1328 			continue;
1329 		options.identity_keys[i] = NULL;
1330 		id = xcalloc(1, sizeof(*id));
1331 		id->agent_fd = -1;
1332 		id->key = key;
1333 		id->filename = xstrdup(options.identity_files[i]);
1334 		id->userprovided = options.identity_file_userprovided[i];
1335 		TAILQ_INSERT_TAIL(&files, id, next);
1336 	}
1337 	/* list of certificates specified by user */
1338 	for (i = 0; i < options.num_certificate_files; i++) {
1339 		key = options.certificates[i];
1340 		if (!key_is_cert(key) || key->cert == NULL ||
1341 		    key->cert->type != SSH2_CERT_TYPE_USER)
1342 			continue;
1343 		id = xcalloc(1, sizeof(*id));
1344 		id->agent_fd = -1;
1345 		id->key = key;
1346 		id->filename = xstrdup(options.certificate_files[i]);
1347 		id->userprovided = options.certificate_file_userprovided[i];
1348 		TAILQ_INSERT_TAIL(preferred, id, next);
1349 	}
1350 	/* list of keys supported by the agent */
1351 	if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) {
1352 		if (r != SSH_ERR_AGENT_NOT_PRESENT)
1353 			debug("%s: ssh_get_authentication_socket: %s",
1354 			    __func__, ssh_err(r));
1355 	} else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) {
1356 		if (r != SSH_ERR_AGENT_NO_IDENTITIES)
1357 			debug("%s: ssh_fetch_identitylist: %s",
1358 			    __func__, ssh_err(r));
1359 		close(agent_fd);
1360 	} else {
1361 		for (j = 0; j < idlist->nkeys; j++) {
1362 			found = 0;
1363 			TAILQ_FOREACH(id, &files, next) {
1364 				/*
1365 				 * agent keys from the config file are
1366 				 * preferred
1367 				 */
1368 				if (sshkey_equal(idlist->keys[j], id->key)) {
1369 					TAILQ_REMOVE(&files, id, next);
1370 					TAILQ_INSERT_TAIL(preferred, id, next);
1371 					id->agent_fd = agent_fd;
1372 					found = 1;
1373 					break;
1374 				}
1375 			}
1376 			if (!found && !options.identities_only) {
1377 				id = xcalloc(1, sizeof(*id));
1378 				/* XXX "steals" key/comment from idlist */
1379 				id->key = idlist->keys[j];
1380 				id->filename = idlist->comments[j];
1381 				idlist->keys[j] = NULL;
1382 				idlist->comments[j] = NULL;
1383 				id->agent_fd = agent_fd;
1384 				TAILQ_INSERT_TAIL(&agent, id, next);
1385 			}
1386 		}
1387 		ssh_free_identitylist(idlist);
1388 		/* append remaining agent keys */
1389 		for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1390 			TAILQ_REMOVE(&agent, id, next);
1391 			TAILQ_INSERT_TAIL(preferred, id, next);
1392 		}
1393 		authctxt->agent_fd = agent_fd;
1394 	}
1395 	/* Prefer PKCS11 keys that are explicitly listed */
1396 	TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1397 		if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0)
1398 			continue;
1399 		found = 0;
1400 		TAILQ_FOREACH(id2, &files, next) {
1401 			if (id2->key == NULL ||
1402 			    (id2->key->flags & SSHKEY_FLAG_EXT) == 0)
1403 				continue;
1404 			if (sshkey_equal(id->key, id2->key)) {
1405 				TAILQ_REMOVE(&files, id, next);
1406 				TAILQ_INSERT_TAIL(preferred, id, next);
1407 				found = 1;
1408 				break;
1409 			}
1410 		}
1411 		/* If IdentitiesOnly set and key not found then don't use it */
1412 		if (!found && options.identities_only) {
1413 			TAILQ_REMOVE(&files, id, next);
1414 			explicit_bzero(id, sizeof(*id));
1415 			free(id);
1416 		}
1417 	}
1418 	/* append remaining keys from the config file */
1419 	for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1420 		TAILQ_REMOVE(&files, id, next);
1421 		TAILQ_INSERT_TAIL(preferred, id, next);
1422 	}
1423 	/* finally, filter by PubkeyAcceptedKeyTypes */
1424 	TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
1425 		if (id->key != NULL &&
1426 		    match_pattern_list(sshkey_ssh_name(id->key),
1427 		    options.pubkey_key_types, 0) != 1) {
1428 			debug("Skipping %s key %s - "
1429 			    "not in PubkeyAcceptedKeyTypes",
1430 			    sshkey_ssh_name(id->key), id->filename);
1431 			TAILQ_REMOVE(preferred, id, next);
1432 			sshkey_free(id->key);
1433 			free(id->filename);
1434 			memset(id, 0, sizeof(*id));
1435 			continue;
1436 		}
1437 		debug2("key: %s (%p)%s%s", id->filename, id->key,
1438 		    id->userprovided ? ", explicit" : "",
1439 		    id->agent_fd != -1 ? ", agent" : "");
1440 	}
1441 }
1442 
1443 static void
1444 pubkey_cleanup(Authctxt *authctxt)
1445 {
1446 	Identity *id;
1447 
1448 	if (authctxt->agent_fd != -1)
1449 		ssh_close_authentication_socket(authctxt->agent_fd);
1450 	for (id = TAILQ_FIRST(&authctxt->keys); id;
1451 	    id = TAILQ_FIRST(&authctxt->keys)) {
1452 		TAILQ_REMOVE(&authctxt->keys, id, next);
1453 		sshkey_free(id->key);
1454 		free(id->filename);
1455 		free(id);
1456 	}
1457 }
1458 
1459 static void
1460 pubkey_reset(Authctxt *authctxt)
1461 {
1462 	Identity *id;
1463 
1464 	TAILQ_FOREACH(id, &authctxt->keys, next)
1465 		id->tried = 0;
1466 }
1467 
1468 static int
1469 try_identity(Identity *id)
1470 {
1471 	if (!id->key)
1472 		return (0);
1473 	if (key_type_plain(id->key->type) == KEY_RSA &&
1474 	    (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1475 		debug("Skipped %s key %s for RSA/MD5 server",
1476 		    key_type(id->key), id->filename);
1477 		return (0);
1478 	}
1479 	return 1;
1480 }
1481 
1482 int
1483 userauth_pubkey(Authctxt *authctxt)
1484 {
1485 	Identity *id;
1486 	int sent = 0;
1487 	char *fp;
1488 
1489 	while ((id = TAILQ_FIRST(&authctxt->keys))) {
1490 		if (id->tried++)
1491 			return (0);
1492 		/* move key to the end of the queue */
1493 		TAILQ_REMOVE(&authctxt->keys, id, next);
1494 		TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1495 		/*
1496 		 * send a test message if we have the public key. for
1497 		 * encrypted keys we cannot do this and have to load the
1498 		 * private key instead
1499 		 */
1500 		if (id->key != NULL) {
1501 			if (try_identity(id)) {
1502 				if ((fp = sshkey_fingerprint(id->key,
1503 				    options.fingerprint_hash,
1504 				    SSH_FP_DEFAULT)) == NULL) {
1505 					error("%s: sshkey_fingerprint failed",
1506 					    __func__);
1507 					return 0;
1508 				}
1509 				debug("Offering public key: %s %s %s",
1510 				    sshkey_type(id->key), fp, id->filename);
1511 				free(fp);
1512 				sent = send_pubkey_test(authctxt, id);
1513 			}
1514 		} else {
1515 			debug("Trying private key: %s", id->filename);
1516 			id->key = load_identity_file(id);
1517 			if (id->key != NULL) {
1518 				if (try_identity(id)) {
1519 					id->isprivate = 1;
1520 					sent = sign_and_send_pubkey(
1521 					    authctxt, id);
1522 				}
1523 				key_free(id->key);
1524 				id->key = NULL;
1525 				id->isprivate = 0;
1526 			}
1527 		}
1528 		if (sent)
1529 			return (sent);
1530 	}
1531 	return (0);
1532 }
1533 
1534 /*
1535  * Send userauth request message specifying keyboard-interactive method.
1536  */
1537 int
1538 userauth_kbdint(Authctxt *authctxt)
1539 {
1540 	static int attempt = 0;
1541 
1542 	if (attempt++ >= options.number_of_password_prompts)
1543 		return 0;
1544 	/* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1545 	if (attempt > 1 && !authctxt->info_req_seen) {
1546 		debug3("userauth_kbdint: disable: no info_req_seen");
1547 		dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1548 		return 0;
1549 	}
1550 
1551 	debug2("userauth_kbdint");
1552 	packet_start(SSH2_MSG_USERAUTH_REQUEST);
1553 	packet_put_cstring(authctxt->server_user);
1554 	packet_put_cstring(authctxt->service);
1555 	packet_put_cstring(authctxt->method->name);
1556 	packet_put_cstring("");					/* lang */
1557 	packet_put_cstring(options.kbd_interactive_devices ?
1558 	    options.kbd_interactive_devices : "");
1559 	packet_send();
1560 
1561 	dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1562 	return 1;
1563 }
1564 
1565 /*
1566  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1567  */
1568 int
1569 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh)
1570 {
1571 	Authctxt *authctxt = ssh->authctxt;
1572 	char *name, *inst, *lang, *prompt, *response;
1573 	u_int num_prompts, i;
1574 	int echo = 0;
1575 
1576 	debug2("input_userauth_info_req");
1577 
1578 	if (authctxt == NULL)
1579 		fatal("input_userauth_info_req: no authentication context");
1580 
1581 	authctxt->info_req_seen = 1;
1582 
1583 	name = packet_get_string(NULL);
1584 	inst = packet_get_string(NULL);
1585 	lang = packet_get_string(NULL);
1586 	if (strlen(name) > 0)
1587 		logit("%s", name);
1588 	if (strlen(inst) > 0)
1589 		logit("%s", inst);
1590 	free(name);
1591 	free(inst);
1592 	free(lang);
1593 
1594 	num_prompts = packet_get_int();
1595 	/*
1596 	 * Begin to build info response packet based on prompts requested.
1597 	 * We commit to providing the correct number of responses, so if
1598 	 * further on we run into a problem that prevents this, we have to
1599 	 * be sure and clean this up and send a correct error response.
1600 	 */
1601 	packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1602 	packet_put_int(num_prompts);
1603 
1604 	debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1605 	for (i = 0; i < num_prompts; i++) {
1606 		prompt = packet_get_string(NULL);
1607 		echo = packet_get_char();
1608 
1609 		response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1610 
1611 		packet_put_cstring(response);
1612 		explicit_bzero(response, strlen(response));
1613 		free(response);
1614 		free(prompt);
1615 	}
1616 	packet_check_eom(); /* done with parsing incoming message. */
1617 
1618 	packet_add_padding(64);
1619 	packet_send();
1620 	return 0;
1621 }
1622 
1623 static int
1624 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp,
1625     const u_char *data, size_t datalen)
1626 {
1627 	struct sshbuf *b;
1628 	struct stat st;
1629 	pid_t pid;
1630 	int i, r, to[2], from[2], status, sock = packet_get_connection_in();
1631 	u_char rversion = 0, version = 2;
1632 	void (*osigchld)(int);
1633 
1634 	*sigp = NULL;
1635 	*lenp = 0;
1636 
1637 	if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1638 		error("%s: not installed: %s", __func__, strerror(errno));
1639 		return -1;
1640 	}
1641 	if (fflush(stdout) != 0) {
1642 		error("%s: fflush: %s", __func__, strerror(errno));
1643 		return -1;
1644 	}
1645 	if (pipe(to) < 0) {
1646 		error("%s: pipe: %s", __func__, strerror(errno));
1647 		return -1;
1648 	}
1649 	if (pipe(from) < 0) {
1650 		error("%s: pipe: %s", __func__, strerror(errno));
1651 		return -1;
1652 	}
1653 	if ((pid = fork()) < 0) {
1654 		error("%s: fork: %s", __func__, strerror(errno));
1655 		return -1;
1656 	}
1657 	osigchld = signal(SIGCHLD, SIG_DFL);
1658 	if (pid == 0) {
1659 		/* keep the socket on exec */
1660 		fcntl(sock, F_SETFD, 0);
1661 		permanently_drop_suid(getuid());
1662 		close(from[0]);
1663 		if (dup2(from[1], STDOUT_FILENO) < 0)
1664 			fatal("%s: dup2: %s", __func__, strerror(errno));
1665 		close(to[1]);
1666 		if (dup2(to[0], STDIN_FILENO) < 0)
1667 			fatal("%s: dup2: %s", __func__, strerror(errno));
1668 		close(from[1]);
1669 		close(to[0]);
1670 		/* Close everything but stdio and the socket */
1671 		for (i = STDERR_FILENO + 1; i < sock; i++)
1672 			close(i);
1673 		closefrom(sock + 1);
1674 		debug3("%s: [child] pid=%ld, exec %s",
1675 		    __func__, (long)getpid(), _PATH_SSH_KEY_SIGN);
1676 		execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL);
1677 		fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN,
1678 		    strerror(errno));
1679 	}
1680 	close(from[1]);
1681 	close(to[0]);
1682 
1683 	if ((b = sshbuf_new()) == NULL)
1684 		fatal("%s: sshbuf_new failed", __func__);
1685 	/* send # of sock, data to be signed */
1686 	if ((r = sshbuf_put_u32(b, sock)) != 0 ||
1687 	    (r = sshbuf_put_string(b, data, datalen)) != 0)
1688 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
1689 	if (ssh_msg_send(to[1], version, b) == -1)
1690 		fatal("%s: couldn't send request", __func__);
1691 	sshbuf_reset(b);
1692 	r = ssh_msg_recv(from[0], b);
1693 	close(from[0]);
1694 	close(to[1]);
1695 	if (r < 0) {
1696 		error("%s: no reply", __func__);
1697 		goto fail;
1698 	}
1699 
1700 	errno = 0;
1701 	while (waitpid(pid, &status, 0) < 0) {
1702 		if (errno != EINTR) {
1703 			error("%s: waitpid %ld: %s",
1704 			    __func__, (long)pid, strerror(errno));
1705 			goto fail;
1706 		}
1707 	}
1708 	if (!WIFEXITED(status)) {
1709 		error("%s: exited abnormally", __func__);
1710 		goto fail;
1711 	}
1712 	if (WEXITSTATUS(status) != 0) {
1713 		error("%s: exited with status %d",
1714 		    __func__, WEXITSTATUS(status));
1715 		goto fail;
1716 	}
1717 	if ((r = sshbuf_get_u8(b, &rversion)) != 0) {
1718 		error("%s: buffer error: %s", __func__, ssh_err(r));
1719 		goto fail;
1720 	}
1721 	if (rversion != version) {
1722 		error("%s: bad version", __func__);
1723 		goto fail;
1724 	}
1725 	if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) {
1726 		error("%s: buffer error: %s", __func__, ssh_err(r));
1727  fail:
1728 		signal(SIGCHLD, osigchld);
1729 		sshbuf_free(b);
1730 		return -1;
1731 	}
1732 	signal(SIGCHLD, osigchld);
1733 	sshbuf_free(b);
1734 
1735 	return 0;
1736 }
1737 
1738 int
1739 userauth_hostbased(Authctxt *authctxt)
1740 {
1741 	struct ssh *ssh = active_state;
1742 	struct sshkey *private = NULL;
1743 	struct sshbuf *b = NULL;
1744 	const char *service;
1745 	u_char *sig = NULL, *keyblob = NULL;
1746 	char *fp = NULL, *chost = NULL, *lname = NULL;
1747 	size_t siglen = 0, keylen = 0;
1748 	int i, r, success = 0;
1749 
1750 	if (authctxt->ktypes == NULL) {
1751 		authctxt->oktypes = xstrdup(options.hostbased_key_types);
1752 		authctxt->ktypes = authctxt->oktypes;
1753 	}
1754 
1755 	/*
1756 	 * Work through each listed type pattern in HostbasedKeyTypes,
1757 	 * trying each hostkey that matches the type in turn.
1758 	 */
1759 	for (;;) {
1760 		if (authctxt->active_ktype == NULL)
1761 			authctxt->active_ktype = strsep(&authctxt->ktypes, ",");
1762 		if (authctxt->active_ktype == NULL ||
1763 		    *authctxt->active_ktype == '\0')
1764 			break;
1765 		debug3("%s: trying key type %s", __func__,
1766 		    authctxt->active_ktype);
1767 
1768 		/* check for a useful key */
1769 		private = NULL;
1770 		for (i = 0; i < authctxt->sensitive->nkeys; i++) {
1771 			if (authctxt->sensitive->keys[i] == NULL ||
1772 			    authctxt->sensitive->keys[i]->type == KEY_UNSPEC)
1773 				continue;
1774 			if (match_pattern_list(
1775 			    sshkey_ssh_name(authctxt->sensitive->keys[i]),
1776 			    authctxt->active_ktype, 0) != 1)
1777 				continue;
1778 			/* we take and free the key */
1779 			private = authctxt->sensitive->keys[i];
1780 			authctxt->sensitive->keys[i] = NULL;
1781 			break;
1782 		}
1783 		/* Found one */
1784 		if (private != NULL)
1785 			break;
1786 		/* No more keys of this type; advance */
1787 		authctxt->active_ktype = NULL;
1788 	}
1789 	if (private == NULL) {
1790 		free(authctxt->oktypes);
1791 		authctxt->oktypes = authctxt->ktypes = NULL;
1792 		authctxt->active_ktype = NULL;
1793 		debug("No more client hostkeys for hostbased authentication.");
1794 		goto out;
1795 	}
1796 
1797 	if ((fp = sshkey_fingerprint(private, options.fingerprint_hash,
1798 	    SSH_FP_DEFAULT)) == NULL) {
1799 		error("%s: sshkey_fingerprint failed", __func__);
1800 		goto out;
1801 	}
1802 	debug("%s: trying hostkey %s %s",
1803 	    __func__, sshkey_ssh_name(private), fp);
1804 
1805 	/* figure out a name for the client host */
1806 	if ((lname = get_local_name(packet_get_connection_in())) == NULL) {
1807 		error("%s: cannot get local ipaddr/name", __func__);
1808 		goto out;
1809 	}
1810 
1811 	/* XXX sshbuf_put_stringf? */
1812 	xasprintf(&chost, "%s.", lname);
1813 	debug2("%s: chost %s", __func__, chost);
1814 
1815 	service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1816 	    authctxt->service;
1817 
1818 	/* construct data */
1819 	if ((b = sshbuf_new()) == NULL) {
1820 		error("%s: sshbuf_new failed", __func__);
1821 		goto out;
1822 	}
1823 	if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) {
1824 		error("%s: sshkey_to_blob: %s", __func__, ssh_err(r));
1825 		goto out;
1826 	}
1827 	if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 ||
1828 	    (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1829 	    (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
1830 	    (r = sshbuf_put_cstring(b, service)) != 0 ||
1831 	    (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
1832 	    (r = sshbuf_put_cstring(b, key_ssh_name(private))) != 0 ||
1833 	    (r = sshbuf_put_string(b, keyblob, keylen)) != 0 ||
1834 	    (r = sshbuf_put_cstring(b, chost)) != 0 ||
1835 	    (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) {
1836 		error("%s: buffer error: %s", __func__, ssh_err(r));
1837 		goto out;
1838 	}
1839 
1840 #ifdef DEBUG_PK
1841 	sshbuf_dump(b, stderr);
1842 #endif
1843 	if (authctxt->sensitive->external_keysign)
1844 		r = ssh_keysign(private, &sig, &siglen,
1845 		    sshbuf_ptr(b), sshbuf_len(b));
1846 	else if ((r = sshkey_sign(private, &sig, &siglen,
1847 	    sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0)
1848 		debug("%s: sshkey_sign: %s", __func__, ssh_err(r));
1849 	if (r != 0) {
1850 		error("sign using hostkey %s %s failed",
1851 		    sshkey_ssh_name(private), fp);
1852 		goto out;
1853 	}
1854 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1855 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1856 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1857 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1858 	    (r = sshpkt_put_cstring(ssh, key_ssh_name(private))) != 0 ||
1859 	    (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 ||
1860 	    (r = sshpkt_put_cstring(ssh, chost)) != 0 ||
1861 	    (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 ||
1862 	    (r = sshpkt_put_string(ssh, sig, siglen)) != 0 ||
1863 	    (r = sshpkt_send(ssh)) != 0) {
1864 		error("%s: packet error: %s", __func__, ssh_err(r));
1865 		goto out;
1866 	}
1867 	success = 1;
1868 
1869  out:
1870 	if (sig != NULL) {
1871 		explicit_bzero(sig, siglen);
1872 		free(sig);
1873 	}
1874 	free(keyblob);
1875 	free(lname);
1876 	free(fp);
1877 	free(chost);
1878 	sshkey_free(private);
1879 	sshbuf_free(b);
1880 
1881 	return success;
1882 }
1883 
1884 /* find auth method */
1885 
1886 /*
1887  * given auth method name, if configurable options permit this method fill
1888  * in auth_ident field and return true, otherwise return false.
1889  */
1890 static int
1891 authmethod_is_enabled(Authmethod *method)
1892 {
1893 	if (method == NULL)
1894 		return 0;
1895 	/* return false if options indicate this method is disabled */
1896 	if  (method->enabled == NULL || *method->enabled == 0)
1897 		return 0;
1898 	/* return false if batch mode is enabled but method needs interactive mode */
1899 	if  (method->batch_flag != NULL && *method->batch_flag != 0)
1900 		return 0;
1901 	return 1;
1902 }
1903 
1904 static Authmethod *
1905 authmethod_lookup(const char *name)
1906 {
1907 	Authmethod *method = NULL;
1908 	if (name != NULL)
1909 		for (method = authmethods; method->name != NULL; method++)
1910 			if (strcmp(name, method->name) == 0)
1911 				return method;
1912 	debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1913 	return NULL;
1914 }
1915 
1916 /* XXX internal state */
1917 static Authmethod *current = NULL;
1918 static char *supported = NULL;
1919 static char *preferred = NULL;
1920 
1921 /*
1922  * Given the authentication method list sent by the server, return the
1923  * next method we should try.  If the server initially sends a nil list,
1924  * use a built-in default list.
1925  */
1926 static Authmethod *
1927 authmethod_get(char *authlist)
1928 {
1929 	char *name = NULL;
1930 	u_int next;
1931 
1932 	/* Use a suitable default if we're passed a nil list.  */
1933 	if (authlist == NULL || strlen(authlist) == 0)
1934 		authlist = options.preferred_authentications;
1935 
1936 	if (supported == NULL || strcmp(authlist, supported) != 0) {
1937 		debug3("start over, passed a different list %s", authlist);
1938 		free(supported);
1939 		supported = xstrdup(authlist);
1940 		preferred = options.preferred_authentications;
1941 		debug3("preferred %s", preferred);
1942 		current = NULL;
1943 	} else if (current != NULL && authmethod_is_enabled(current))
1944 		return current;
1945 
1946 	for (;;) {
1947 		if ((name = match_list(preferred, supported, &next)) == NULL) {
1948 			debug("No more authentication methods to try.");
1949 			current = NULL;
1950 			return NULL;
1951 		}
1952 		preferred += next;
1953 		debug3("authmethod_lookup %s", name);
1954 		debug3("remaining preferred: %s", preferred);
1955 		if ((current = authmethod_lookup(name)) != NULL &&
1956 		    authmethod_is_enabled(current)) {
1957 			debug3("authmethod_is_enabled %s", name);
1958 			debug("Next authentication method: %s", name);
1959 			free(name);
1960 			return current;
1961 		}
1962 		free(name);
1963 	}
1964 }
1965 
1966 static char *
1967 authmethods_get(void)
1968 {
1969 	Authmethod *method = NULL;
1970 	Buffer b;
1971 	char *list;
1972 
1973 	buffer_init(&b);
1974 	for (method = authmethods; method->name != NULL; method++) {
1975 		if (authmethod_is_enabled(method)) {
1976 			if (buffer_len(&b) > 0)
1977 				buffer_append(&b, ",", 1);
1978 			buffer_append(&b, method->name, strlen(method->name));
1979 		}
1980 	}
1981 	if ((list = sshbuf_dup_string(&b)) == NULL)
1982 		fatal("%s: sshbuf_dup_string failed", __func__);
1983 	buffer_free(&b);
1984 	return list;
1985 }
1986 
1987