xref: /openssh-portable/sshconnect2.c (revision af889a40)
1 /* $OpenBSD: sshconnect2.c,v 1.328 2020/10/04 09:45:01 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 <fcntl.h>
36 #include <netdb.h>
37 #include <pwd.h>
38 #include <signal.h>
39 #include <stdio.h>
40 #include <string.h>
41 #include <stdarg.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 "sshbuf.h"
53 #include "packet.h"
54 #include "compat.h"
55 #include "cipher.h"
56 #include "sshkey.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 #include "ssh-sk.h"
76 #include "sk-api.h"
77 
78 #ifdef GSSAPI
79 #include "ssh-gss.h"
80 #endif
81 
82 /* import */
83 extern char *client_version_string;
84 extern char *server_version_string;
85 extern Options options;
86 
87 /*
88  * SSH2 key exchange
89  */
90 
91 u_char *session_id2 = NULL;
92 u_int session_id2_len = 0;
93 
94 char *xxx_host;
95 struct sockaddr *xxx_hostaddr;
96 
97 static int
98 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh)
99 {
100 	int cert_downgraded = 0;
101 
102 	if (verify_host_key(xxx_host, xxx_hostaddr, hostkey,
103 	    &cert_downgraded) == -1)
104 		fatal("Host key verification failed.");
105 	if (cert_downgraded)
106 		ssh->kex->flags |= KEX_HOSTCERT_CONVERT;
107 	return 0;
108 }
109 
110 /* Returns the first item from a comma-separated algorithm list */
111 static char *
112 first_alg(const char *algs)
113 {
114 	char *ret, *cp;
115 
116 	ret = xstrdup(algs);
117 	if ((cp = strchr(ret, ',')) != NULL)
118 		*cp = '\0';
119 	return ret;
120 }
121 
122 static char *
123 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
124 {
125 	char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL;
126 	char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL;
127 	size_t maxlen;
128 	struct hostkeys *hostkeys = NULL;
129 	int ktype;
130 	u_int i;
131 
132 	/* Find all hostkeys for this hostname */
133 	get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
134 	hostkeys = init_hostkeys();
135 	for (i = 0; i < options.num_user_hostfiles; i++)
136 		load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
137 	for (i = 0; i < options.num_system_hostfiles; i++)
138 		load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
139 
140 	/*
141 	 * If a plain public key exists that matches the type of the best
142 	 * preference HostkeyAlgorithms, then use the whole list as is.
143 	 * Note that we ignore whether the best preference algorithm is a
144 	 * certificate type, as sshconnect.c will downgrade certs to
145 	 * plain keys if necessary.
146 	 */
147 	best = first_alg(options.hostkeyalgorithms);
148 	if (lookup_key_in_hostkeys_by_type(hostkeys,
149 	    sshkey_type_plain(sshkey_type_from_name(best)),
150 	    sshkey_ecdsa_nid_from_name(best), NULL)) {
151 		debug3("%s: have matching best-preference key type %s, "
152 		    "using HostkeyAlgorithms verbatim", __func__, best);
153 		ret = xstrdup(options.hostkeyalgorithms);
154 		goto out;
155 	}
156 
157 	/*
158 	 * Otherwise, prefer the host key algorithms that match known keys
159 	 * while keeping the ordering of HostkeyAlgorithms as much as possible.
160 	 */
161 	oavail = avail = xstrdup(options.hostkeyalgorithms);
162 	maxlen = strlen(avail) + 1;
163 	first = xmalloc(maxlen);
164 	last = xmalloc(maxlen);
165 	*first = *last = '\0';
166 
167 #define ALG_APPEND(to, from) \
168 	do { \
169 		if (*to != '\0') \
170 			strlcat(to, ",", maxlen); \
171 		strlcat(to, from, maxlen); \
172 	} while (0)
173 
174 	while ((alg = strsep(&avail, ",")) && *alg != '\0') {
175 		if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
176 			fatal("%s: unknown alg %s", __func__, alg);
177 		/*
178 		 * If we have a @cert-authority marker in known_hosts then
179 		 * prefer all certificate algorithms.
180 		 */
181 		if (sshkey_type_is_cert(ktype) &&
182 		    lookup_marker_in_hostkeys(hostkeys, MRK_CA)) {
183 			ALG_APPEND(first, alg);
184 			continue;
185 		}
186 		/* If the key appears in known_hosts then prefer it */
187 		if (lookup_key_in_hostkeys_by_type(hostkeys,
188 		    sshkey_type_plain(ktype),
189 		    sshkey_ecdsa_nid_from_name(alg), NULL)) {
190 			ALG_APPEND(first, alg);
191 			continue;
192 		}
193 		/* Otherwise, put it last */
194 		ALG_APPEND(last, alg);
195 	}
196 #undef ALG_APPEND
197 	xasprintf(&ret, "%s%s%s", first,
198 	    (*first == '\0' || *last == '\0') ? "" : ",", last);
199 	if (*first != '\0')
200 		debug3("%s: prefer hostkeyalgs: %s", __func__, first);
201 
202  out:
203 	free(best);
204 	free(first);
205 	free(last);
206 	free(hostname);
207 	free(oavail);
208 	free_hostkeys(hostkeys);
209 
210 	return ret;
211 }
212 
213 void
214 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port)
215 {
216 	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
217 	char *s, *all_key;
218 	int r, use_known_hosts_order = 0;
219 
220 	xxx_host = host;
221 	xxx_hostaddr = hostaddr;
222 
223 	/*
224 	 * If the user has not specified HostkeyAlgorithms, or has only
225 	 * appended or removed algorithms from that list then prefer algorithms
226 	 * that are in the list that are supported by known_hosts keys.
227 	 */
228 	if (options.hostkeyalgorithms == NULL ||
229 	    options.hostkeyalgorithms[0] == '-' ||
230 	    options.hostkeyalgorithms[0] == '+')
231 		use_known_hosts_order = 1;
232 
233 	/* Expand or fill in HostkeyAlgorithms */
234 	all_key = sshkey_alg_list(0, 0, 1, ',');
235 	if (kex_assemble_names(&options.hostkeyalgorithms,
236 	    kex_default_pk_alg(), all_key) != 0)
237 		fatal("%s: kex_assemble_namelist", __func__);
238 	free(all_key);
239 
240 	if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL)
241 		fatal("%s: kex_names_cat", __func__);
242 	myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s);
243 	myproposal[PROPOSAL_ENC_ALGS_CTOS] =
244 	    compat_cipher_proposal(options.ciphers);
245 	myproposal[PROPOSAL_ENC_ALGS_STOC] =
246 	    compat_cipher_proposal(options.ciphers);
247 	myproposal[PROPOSAL_COMP_ALGS_CTOS] =
248 	    myproposal[PROPOSAL_COMP_ALGS_STOC] =
249 	    (char *)compression_alg_list(options.compression);
250 	myproposal[PROPOSAL_MAC_ALGS_CTOS] =
251 	    myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
252 	if (use_known_hosts_order) {
253 		/* Query known_hosts and prefer algorithms that appear there */
254 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
255 		    compat_pkalg_proposal(
256 		    order_hostkeyalgs(host, hostaddr, port));
257 	} else {
258 		/* Use specified HostkeyAlgorithms exactly */
259 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
260 		    compat_pkalg_proposal(options.hostkeyalgorithms);
261 	}
262 
263 	if (options.rekey_limit || options.rekey_interval)
264 		ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
265 		    options.rekey_interval);
266 
267 	/* start key exchange */
268 	if ((r = kex_setup(ssh, myproposal)) != 0)
269 		fatal("kex_setup: %s", ssh_err(r));
270 #ifdef WITH_OPENSSL
271 	ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client;
272 	ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client;
273 	ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client;
274 	ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client;
275 	ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client;
276 	ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
277 	ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
278 # ifdef OPENSSL_HAS_ECC
279 	ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client;
280 # endif
281 #endif
282 	ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client;
283 	ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client;
284 	ssh->kex->verify_host_key=&verify_host_key_callback;
285 
286 	ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done);
287 
288 	/* remove ext-info from the KEX proposals for rekeying */
289 	myproposal[PROPOSAL_KEX_ALGS] =
290 	    compat_kex_proposal(options.kex_algorithms);
291 	if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0)
292 		fatal("kex_prop2buf: %s", ssh_err(r));
293 
294 	session_id2 = ssh->kex->session_id;
295 	session_id2_len = ssh->kex->session_id_len;
296 
297 #ifdef DEBUG_KEXDH
298 	/* send 1st encrypted/maced/compressed message */
299 	if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
300 	    (r = sshpkt_put_cstring(ssh, "markus")) != 0 ||
301 	    (r = sshpkt_send(ssh)) != 0 ||
302 	    (r = ssh_packet_write_wait(ssh)) != 0)
303 		fatal("%s: %s", __func__, ssh_err(r));
304 #endif
305 }
306 
307 /*
308  * Authenticate user
309  */
310 
311 typedef struct cauthctxt Authctxt;
312 typedef struct cauthmethod Authmethod;
313 typedef struct identity Identity;
314 typedef struct idlist Idlist;
315 
316 struct identity {
317 	TAILQ_ENTRY(identity) next;
318 	int	agent_fd;		/* >=0 if agent supports key */
319 	struct sshkey	*key;		/* public/private key */
320 	char	*filename;		/* comment for agent-only keys */
321 	int	tried;
322 	int	isprivate;		/* key points to the private key */
323 	int	userprovided;
324 };
325 TAILQ_HEAD(idlist, identity);
326 
327 struct cauthctxt {
328 	const char *server_user;
329 	const char *local_user;
330 	const char *host;
331 	const char *service;
332 	struct cauthmethod *method;
333 	sig_atomic_t success;
334 	char *authlist;
335 #ifdef GSSAPI
336 	/* gssapi */
337 	gss_OID_set gss_supported_mechs;
338 	u_int mech_tried;
339 #endif
340 	/* pubkey */
341 	struct idlist keys;
342 	int agent_fd;
343 	/* hostbased */
344 	Sensitive *sensitive;
345 	char *oktypes, *ktypes;
346 	const char *active_ktype;
347 	/* kbd-interactive */
348 	int info_req_seen;
349 	int attempt_kbdint;
350 	/* password */
351 	int attempt_passwd;
352 	/* generic */
353 	void *methoddata;
354 };
355 
356 struct cauthmethod {
357 	char	*name;		/* string to compare against server's list */
358 	int	(*userauth)(struct ssh *ssh);
359 	void	(*cleanup)(struct ssh *ssh);
360 	int	*enabled;	/* flag in option struct that enables method */
361 	int	*batch_flag;	/* flag in option struct that disables method */
362 };
363 
364 static int input_userauth_service_accept(int, u_int32_t, struct ssh *);
365 static int input_userauth_ext_info(int, u_int32_t, struct ssh *);
366 static int input_userauth_success(int, u_int32_t, struct ssh *);
367 static int input_userauth_failure(int, u_int32_t, struct ssh *);
368 static int input_userauth_banner(int, u_int32_t, struct ssh *);
369 static int input_userauth_error(int, u_int32_t, struct ssh *);
370 static int input_userauth_info_req(int, u_int32_t, struct ssh *);
371 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *);
372 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *);
373 
374 static int userauth_none(struct ssh *);
375 static int userauth_pubkey(struct ssh *);
376 static int userauth_passwd(struct ssh *);
377 static int userauth_kbdint(struct ssh *);
378 static int userauth_hostbased(struct ssh *);
379 
380 #ifdef GSSAPI
381 static int userauth_gssapi(struct ssh *);
382 static void userauth_gssapi_cleanup(struct ssh *);
383 static int input_gssapi_response(int type, u_int32_t, struct ssh *);
384 static int input_gssapi_token(int type, u_int32_t, struct ssh *);
385 static int input_gssapi_error(int, u_int32_t, struct ssh *);
386 static int input_gssapi_errtok(int, u_int32_t, struct ssh *);
387 #endif
388 
389 void	userauth(struct ssh *, char *);
390 
391 static void pubkey_cleanup(struct ssh *);
392 static int sign_and_send_pubkey(struct ssh *ssh, Identity *);
393 static void pubkey_prepare(Authctxt *);
394 static void pubkey_reset(Authctxt *);
395 static struct sshkey *load_identity_file(Identity *);
396 
397 static Authmethod *authmethod_get(char *authlist);
398 static Authmethod *authmethod_lookup(const char *name);
399 static char *authmethods_get(void);
400 
401 Authmethod authmethods[] = {
402 #ifdef GSSAPI
403 	{"gssapi-with-mic",
404 		userauth_gssapi,
405 		userauth_gssapi_cleanup,
406 		&options.gss_authentication,
407 		NULL},
408 #endif
409 	{"hostbased",
410 		userauth_hostbased,
411 		NULL,
412 		&options.hostbased_authentication,
413 		NULL},
414 	{"publickey",
415 		userauth_pubkey,
416 		NULL,
417 		&options.pubkey_authentication,
418 		NULL},
419 	{"keyboard-interactive",
420 		userauth_kbdint,
421 		NULL,
422 		&options.kbd_interactive_authentication,
423 		&options.batch_mode},
424 	{"password",
425 		userauth_passwd,
426 		NULL,
427 		&options.password_authentication,
428 		&options.batch_mode},
429 	{"none",
430 		userauth_none,
431 		NULL,
432 		NULL,
433 		NULL},
434 	{NULL, NULL, NULL, NULL, NULL}
435 };
436 
437 void
438 ssh_userauth2(struct ssh *ssh, const char *local_user,
439     const char *server_user, char *host, Sensitive *sensitive)
440 {
441 	Authctxt authctxt;
442 	int r;
443 
444 	if (options.challenge_response_authentication)
445 		options.kbd_interactive_authentication = 1;
446 	if (options.preferred_authentications == NULL)
447 		options.preferred_authentications = authmethods_get();
448 
449 	/* setup authentication context */
450 	memset(&authctxt, 0, sizeof(authctxt));
451 	authctxt.server_user = server_user;
452 	authctxt.local_user = local_user;
453 	authctxt.host = host;
454 	authctxt.service = "ssh-connection";		/* service name */
455 	authctxt.success = 0;
456 	authctxt.method = authmethod_lookup("none");
457 	authctxt.authlist = NULL;
458 	authctxt.methoddata = NULL;
459 	authctxt.sensitive = sensitive;
460 	authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL;
461 	authctxt.info_req_seen = 0;
462 	authctxt.attempt_kbdint = 0;
463 	authctxt.attempt_passwd = 0;
464 #if GSSAPI
465 	authctxt.gss_supported_mechs = NULL;
466 	authctxt.mech_tried = 0;
467 #endif
468 	authctxt.agent_fd = -1;
469 	pubkey_prepare(&authctxt);
470 	if (authctxt.method == NULL) {
471 		fatal("%s: internal error: cannot send userauth none request",
472 		    __func__);
473 	}
474 
475 	if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 ||
476 	    (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 ||
477 	    (r = sshpkt_send(ssh)) != 0)
478 		fatal("%s: %s", __func__, ssh_err(r));
479 
480 	ssh->authctxt = &authctxt;
481 	ssh_dispatch_init(ssh, &input_userauth_error);
482 	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info);
483 	ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept);
484 	ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success);	/* loop until success */
485 	pubkey_cleanup(ssh);
486 	ssh->authctxt = NULL;
487 
488 	ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
489 
490 	if (!authctxt.success)
491 		fatal("Authentication failed.");
492 	debug("Authentication succeeded (%s).", authctxt.method->name);
493 }
494 
495 /* ARGSUSED */
496 static int
497 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh)
498 {
499 	int r;
500 
501 	if (ssh_packet_remaining(ssh) > 0) {
502 		char *reply;
503 
504 		if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0)
505 			goto out;
506 		debug2("service_accept: %s", reply);
507 		free(reply);
508 	} else {
509 		debug2("buggy server: service_accept w/o service");
510 	}
511 	if ((r = sshpkt_get_end(ssh)) != 0)
512 		goto out;
513 	debug("SSH2_MSG_SERVICE_ACCEPT received");
514 
515 	/* initial userauth request */
516 	userauth_none(ssh);
517 
518 	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error);
519 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
520 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
521 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
522 	r = 0;
523  out:
524 	return r;
525 }
526 
527 /* ARGSUSED */
528 static int
529 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh)
530 {
531 	return kex_input_ext_info(type, seqnr, ssh);
532 }
533 
534 void
535 userauth(struct ssh *ssh, char *authlist)
536 {
537 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
538 
539 	if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
540 		authctxt->method->cleanup(ssh);
541 
542 	free(authctxt->methoddata);
543 	authctxt->methoddata = NULL;
544 	if (authlist == NULL) {
545 		authlist = authctxt->authlist;
546 	} else {
547 		free(authctxt->authlist);
548 		authctxt->authlist = authlist;
549 	}
550 	for (;;) {
551 		Authmethod *method = authmethod_get(authlist);
552 		if (method == NULL)
553 			fatal("%s@%s: Permission denied (%s).",
554 			    authctxt->server_user, authctxt->host, authlist);
555 		authctxt->method = method;
556 
557 		/* reset the per method handler */
558 		ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN,
559 		    SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
560 
561 		/* and try new method */
562 		if (method->userauth(ssh) != 0) {
563 			debug2("we sent a %s packet, wait for reply", method->name);
564 			break;
565 		} else {
566 			debug2("we did not send a packet, disable method");
567 			method->enabled = NULL;
568 		}
569 	}
570 }
571 
572 /* ARGSUSED */
573 static int
574 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh)
575 {
576 	fatal("%s: bad message during authentication: type %d", __func__, type);
577 	return 0;
578 }
579 
580 /* ARGSUSED */
581 static int
582 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh)
583 {
584 	char *msg = NULL;
585 	size_t len;
586 	int r;
587 
588 	debug3("%s", __func__);
589 	if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 ||
590 	    (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0)
591 		goto out;
592 	if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO)
593 		fmprintf(stderr, "%s", msg);
594 	r = 0;
595  out:
596 	free(msg);
597 	return r;
598 }
599 
600 /* ARGSUSED */
601 static int
602 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh)
603 {
604 	Authctxt *authctxt = ssh->authctxt;
605 
606 	if (authctxt == NULL)
607 		fatal("%s: no authentication context", __func__);
608 	free(authctxt->authlist);
609 	authctxt->authlist = NULL;
610 	if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
611 		authctxt->method->cleanup(ssh);
612 	free(authctxt->methoddata);
613 	authctxt->methoddata = NULL;
614 	authctxt->success = 1;			/* break out */
615 	return 0;
616 }
617 
618 #if 0
619 static int
620 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh)
621 {
622 	Authctxt *authctxt = ssh->authctxt;
623 
624 	if (authctxt == NULL)
625 		fatal("%s: no authentication context", __func__);
626 
627 	fatal("Unexpected authentication success during %s.",
628 	    authctxt->method->name);
629 	return 0;
630 }
631 #endif
632 
633 /* ARGSUSED */
634 static int
635 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh)
636 {
637 	Authctxt *authctxt = ssh->authctxt;
638 	char *authlist = NULL;
639 	u_char partial;
640 
641 	if (authctxt == NULL)
642 		fatal("input_userauth_failure: no authentication context");
643 
644 	if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 ||
645 	    sshpkt_get_u8(ssh, &partial) != 0 ||
646 	    sshpkt_get_end(ssh) != 0)
647 		goto out;
648 
649 	if (partial != 0) {
650 		verbose("Authenticated with partial success.");
651 		/* reset state */
652 		pubkey_reset(authctxt);
653 	}
654 	debug("Authentications that can continue: %s", authlist);
655 
656 	userauth(ssh, authlist);
657 	authlist = NULL;
658  out:
659 	free(authlist);
660 	return 0;
661 }
662 
663 /*
664  * Format an identity for logging including filename, key type, fingerprint
665  * and location (agent, etc.). Caller must free.
666  */
667 static char *
668 format_identity(Identity *id)
669 {
670 	char *fp = NULL, *ret = NULL;
671 	const char *note = "";
672 
673 	if (id->key != NULL) {
674 	     fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
675 		    SSH_FP_DEFAULT);
676 	}
677 	if (id->key) {
678 		if ((id->key->flags & SSHKEY_FLAG_EXT) != 0)
679 			note = " token";
680 		else if (sshkey_is_sk(id->key))
681 			note = " authenticator";
682 	}
683 	xasprintf(&ret, "%s %s%s%s%s%s%s",
684 	    id->filename,
685 	    id->key ? sshkey_type(id->key) : "", id->key ? " " : "",
686 	    fp ? fp : "",
687 	    id->userprovided ? " explicit" : "", note,
688 	    id->agent_fd != -1 ? " agent" : "");
689 	free(fp);
690 	return ret;
691 }
692 
693 /* ARGSUSED */
694 static int
695 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh)
696 {
697 	Authctxt *authctxt = ssh->authctxt;
698 	struct sshkey *key = NULL;
699 	Identity *id = NULL;
700 	int pktype, found = 0, sent = 0;
701 	size_t blen;
702 	char *pkalg = NULL, *fp = NULL, *ident = NULL;
703 	u_char *pkblob = NULL;
704 	int r;
705 
706 	if (authctxt == NULL)
707 		fatal("input_userauth_pk_ok: no authentication context");
708 
709 	if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 ||
710 	    (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 ||
711 	    (r = sshpkt_get_end(ssh)) != 0)
712 		goto done;
713 
714 	if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) {
715 		debug("%s: server sent unknown pkalg %s", __func__, pkalg);
716 		goto done;
717 	}
718 	if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
719 		debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r));
720 		goto done;
721 	}
722 	if (key->type != pktype) {
723 		error("input_userauth_pk_ok: type mismatch "
724 		    "for decoded key (received %d, expected %d)",
725 		    key->type, pktype);
726 		goto done;
727 	}
728 
729 	/*
730 	 * search keys in the reverse order, because last candidate has been
731 	 * moved to the end of the queue.  this also avoids confusion by
732 	 * duplicate keys
733 	 */
734 	TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
735 		if (sshkey_equal(key, id->key)) {
736 			found = 1;
737 			break;
738 		}
739 	}
740 	if (!found || id == NULL) {
741 		fp = sshkey_fingerprint(key, options.fingerprint_hash,
742 		    SSH_FP_DEFAULT);
743 		error("%s: server replied with unknown key: %s %s", __func__,
744 		    sshkey_type(key), fp == NULL ? "<ERROR>" : fp);
745 		goto done;
746 	}
747 	ident = format_identity(id);
748 	debug("Server accepts key: %s", ident);
749 	sent = sign_and_send_pubkey(ssh, id);
750 	r = 0;
751  done:
752 	sshkey_free(key);
753 	free(ident);
754 	free(fp);
755 	free(pkalg);
756 	free(pkblob);
757 
758 	/* try another method if we did not send a packet */
759 	if (r == 0 && sent == 0)
760 		userauth(ssh, NULL);
761 	return r;
762 }
763 
764 #ifdef GSSAPI
765 static int
766 userauth_gssapi(struct ssh *ssh)
767 {
768 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
769 	Gssctxt *gssctxt = NULL;
770 	OM_uint32 min;
771 	int r, ok = 0;
772 	gss_OID mech = NULL;
773 
774 	/* Try one GSSAPI method at a time, rather than sending them all at
775 	 * once. */
776 
777 	if (authctxt->gss_supported_mechs == NULL)
778 		gss_indicate_mechs(&min, &authctxt->gss_supported_mechs);
779 
780 	/* Check to see whether the mechanism is usable before we offer it */
781 	while (authctxt->mech_tried < authctxt->gss_supported_mechs->count &&
782 	    !ok) {
783 		mech = &authctxt->gss_supported_mechs->
784 		    elements[authctxt->mech_tried];
785 		/* My DER encoding requires length<128 */
786 		if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt,
787 		    mech, authctxt->host)) {
788 			ok = 1; /* Mechanism works */
789 		} else {
790 			authctxt->mech_tried++;
791 		}
792 	}
793 
794 	if (!ok || mech == NULL)
795 		return 0;
796 
797 	authctxt->methoddata=(void *)gssctxt;
798 
799 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
800 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
801 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
802 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
803 	    (r = sshpkt_put_u32(ssh, 1)) != 0 ||
804 	    (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 ||
805 	    (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 ||
806 	    (r = sshpkt_put_u8(ssh, mech->length)) != 0 ||
807 	    (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 ||
808 	    (r = sshpkt_send(ssh)) != 0)
809 		fatal("%s: %s", __func__, ssh_err(r));
810 
811 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
812 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
813 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
814 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
815 
816 	authctxt->mech_tried++; /* Move along to next candidate */
817 
818 	return 1;
819 }
820 
821 static void
822 userauth_gssapi_cleanup(struct ssh *ssh)
823 {
824 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
825 	Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata;
826 
827 	ssh_gssapi_delete_ctx(&gssctxt);
828 	authctxt->methoddata = NULL;
829 
830 	free(authctxt->gss_supported_mechs);
831 	authctxt->gss_supported_mechs = NULL;
832 }
833 
834 static OM_uint32
835 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok)
836 {
837 	Authctxt *authctxt = ssh->authctxt;
838 	Gssctxt *gssctxt = authctxt->methoddata;
839 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
840 	gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
841 	gss_buffer_desc gssbuf;
842 	OM_uint32 status, ms, flags;
843 	int r;
844 
845 	status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
846 	    recv_tok, &send_tok, &flags);
847 
848 	if (send_tok.length > 0) {
849 		u_char type = GSS_ERROR(status) ?
850 		    SSH2_MSG_USERAUTH_GSSAPI_ERRTOK :
851 		    SSH2_MSG_USERAUTH_GSSAPI_TOKEN;
852 
853 		if ((r = sshpkt_start(ssh, type)) != 0 ||
854 		    (r = sshpkt_put_string(ssh, send_tok.value,
855 		    send_tok.length)) != 0 ||
856 		    (r = sshpkt_send(ssh)) != 0)
857 			fatal("%s: %s", __func__, ssh_err(r));
858 
859 		gss_release_buffer(&ms, &send_tok);
860 	}
861 
862 	if (status == GSS_S_COMPLETE) {
863 		/* send either complete or MIC, depending on mechanism */
864 		if (!(flags & GSS_C_INTEG_FLAG)) {
865 			if ((r = sshpkt_start(ssh,
866 			    SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 ||
867 			    (r = sshpkt_send(ssh)) != 0)
868 				fatal("%s: %s", __func__, ssh_err(r));
869 		} else {
870 			struct sshbuf *b;
871 
872 			if ((b = sshbuf_new()) == NULL)
873 				fatal("%s: sshbuf_new failed", __func__);
874 			ssh_gssapi_buildmic(b, authctxt->server_user,
875 			    authctxt->service, "gssapi-with-mic");
876 
877 			if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
878 				fatal("%s: sshbuf_mutable_ptr failed", __func__);
879 			gssbuf.length = sshbuf_len(b);
880 
881 			status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
882 
883 			if (!GSS_ERROR(status)) {
884 				if ((r = sshpkt_start(ssh,
885 				    SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 ||
886 				    (r = sshpkt_put_string(ssh, mic.value,
887 				    mic.length)) != 0 ||
888 				    (r = sshpkt_send(ssh)) != 0)
889 					fatal("%s: %s", __func__, ssh_err(r));
890 			}
891 
892 			sshbuf_free(b);
893 			gss_release_buffer(&ms, &mic);
894 		}
895 	}
896 
897 	return status;
898 }
899 
900 /* ARGSUSED */
901 static int
902 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh)
903 {
904 	Authctxt *authctxt = ssh->authctxt;
905 	Gssctxt *gssctxt;
906 	size_t oidlen;
907 	u_char *oidv = NULL;
908 	int r;
909 
910 	if (authctxt == NULL)
911 		fatal("input_gssapi_response: no authentication context");
912 	gssctxt = authctxt->methoddata;
913 
914 	/* Setup our OID */
915 	if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0)
916 		goto done;
917 
918 	if (oidlen <= 2 ||
919 	    oidv[0] != SSH_GSS_OIDTYPE ||
920 	    oidv[1] != oidlen - 2) {
921 		debug("Badly encoded mechanism OID received");
922 		userauth(ssh, NULL);
923 		goto ok;
924 	}
925 
926 	if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
927 		fatal("Server returned different OID than expected");
928 
929 	if ((r = sshpkt_get_end(ssh)) != 0)
930 		goto done;
931 
932 	if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) {
933 		/* Start again with next method on list */
934 		debug("Trying to start again");
935 		userauth(ssh, NULL);
936 		goto ok;
937 	}
938  ok:
939 	r = 0;
940  done:
941 	free(oidv);
942 	return r;
943 }
944 
945 /* ARGSUSED */
946 static int
947 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh)
948 {
949 	Authctxt *authctxt = ssh->authctxt;
950 	gss_buffer_desc recv_tok;
951 	u_char *p = NULL;
952 	size_t len;
953 	OM_uint32 status;
954 	int r;
955 
956 	if (authctxt == NULL)
957 		fatal("input_gssapi_response: no authentication context");
958 
959 	if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
960 	    (r = sshpkt_get_end(ssh)) != 0)
961 		goto out;
962 
963 	recv_tok.value = p;
964 	recv_tok.length = len;
965 	status = process_gssapi_token(ssh, &recv_tok);
966 
967 	/* Start again with the next method in the list */
968 	if (GSS_ERROR(status)) {
969 		userauth(ssh, NULL);
970 		/* ok */
971 	}
972 	r = 0;
973  out:
974 	free(p);
975 	return r;
976 }
977 
978 /* ARGSUSED */
979 static int
980 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh)
981 {
982 	Authctxt *authctxt = ssh->authctxt;
983 	Gssctxt *gssctxt;
984 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
985 	gss_buffer_desc recv_tok;
986 	OM_uint32 ms;
987 	u_char *p = NULL;
988 	size_t len;
989 	int r;
990 
991 	if (authctxt == NULL)
992 		fatal("input_gssapi_response: no authentication context");
993 	gssctxt = authctxt->methoddata;
994 
995 	if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
996 	    (r = sshpkt_get_end(ssh)) != 0) {
997 		free(p);
998 		return r;
999 	}
1000 
1001 	/* Stick it into GSSAPI and see what it says */
1002 	recv_tok.value = p;
1003 	recv_tok.length = len;
1004 	(void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
1005 	    &recv_tok, &send_tok, NULL);
1006 	free(p);
1007 	gss_release_buffer(&ms, &send_tok);
1008 
1009 	/* Server will be returning a failed packet after this one */
1010 	return 0;
1011 }
1012 
1013 /* ARGSUSED */
1014 static int
1015 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
1016 {
1017 	char *msg = NULL;
1018 	char *lang = NULL;
1019 	int r;
1020 
1021 	if ((r = sshpkt_get_u32(ssh, NULL)) != 0 ||	/* maj */
1022 	    (r = sshpkt_get_u32(ssh, NULL)) != 0 ||	/* min */
1023 	    (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 ||
1024 	    (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
1025 		goto out;
1026 	r = sshpkt_get_end(ssh);
1027 	debug("Server GSSAPI Error:\n%s", msg);
1028  out:
1029 	free(msg);
1030 	free(lang);
1031 	return r;
1032 }
1033 #endif /* GSSAPI */
1034 
1035 static int
1036 userauth_none(struct ssh *ssh)
1037 {
1038 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1039 	int r;
1040 
1041 	/* initial userauth request */
1042 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1043 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1044 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1045 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1046 	    (r = sshpkt_send(ssh)) != 0)
1047 		fatal("%s: %s", __func__, ssh_err(r));
1048 	return 1;
1049 }
1050 
1051 static int
1052 userauth_passwd(struct ssh *ssh)
1053 {
1054 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1055 	char *password, *prompt = NULL;
1056 	const char *host = options.host_key_alias ?  options.host_key_alias :
1057 	    authctxt->host;
1058 	int r;
1059 
1060 	if (authctxt->attempt_passwd++ >= options.number_of_password_prompts)
1061 		return 0;
1062 
1063 	if (authctxt->attempt_passwd != 1)
1064 		error("Permission denied, please try again.");
1065 
1066 	xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host);
1067 	password = read_passphrase(prompt, 0);
1068 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1069 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1070 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1071 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1072 	    (r = sshpkt_put_u8(ssh, 0)) != 0 ||
1073 	    (r = sshpkt_put_cstring(ssh, password)) != 0 ||
1074 	    (r = sshpkt_add_padding(ssh, 64)) != 0 ||
1075 	    (r = sshpkt_send(ssh)) != 0)
1076 		fatal("%s: %s", __func__, ssh_err(r));
1077 
1078 	free(prompt);
1079 	if (password != NULL)
1080 		freezero(password, strlen(password));
1081 
1082 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1083 	    &input_userauth_passwd_changereq);
1084 
1085 	return 1;
1086 }
1087 
1088 /*
1089  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
1090  */
1091 /* ARGSUSED */
1092 static int
1093 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh)
1094 {
1095 	Authctxt *authctxt = ssh->authctxt;
1096 	char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL;
1097 	char prompt[256];
1098 	const char *host;
1099 	int r;
1100 
1101 	debug2("input_userauth_passwd_changereq");
1102 
1103 	if (authctxt == NULL)
1104 		fatal("input_userauth_passwd_changereq: "
1105 		    "no authentication context");
1106 	host = options.host_key_alias ? options.host_key_alias : authctxt->host;
1107 
1108 	if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 ||
1109 	    (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
1110 		goto out;
1111 	if (strlen(info) > 0)
1112 		logit("%s", info);
1113 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1114 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1115 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1116 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1117 	    (r = sshpkt_put_u8(ssh, 1)) != 0)	/* additional info */
1118 		goto out;
1119 
1120 	snprintf(prompt, sizeof(prompt),
1121 	    "Enter %.30s@%.128s's old password: ",
1122 	    authctxt->server_user, host);
1123 	password = read_passphrase(prompt, 0);
1124 	if ((r = sshpkt_put_cstring(ssh, password)) != 0)
1125 		goto out;
1126 
1127 	freezero(password, strlen(password));
1128 	password = NULL;
1129 	while (password == NULL) {
1130 		snprintf(prompt, sizeof(prompt),
1131 		    "Enter %.30s@%.128s's new password: ",
1132 		    authctxt->server_user, host);
1133 		password = read_passphrase(prompt, RP_ALLOW_EOF);
1134 		if (password == NULL) {
1135 			/* bail out */
1136 			r = 0;
1137 			goto out;
1138 		}
1139 		snprintf(prompt, sizeof(prompt),
1140 		    "Retype %.30s@%.128s's new password: ",
1141 		    authctxt->server_user, host);
1142 		retype = read_passphrase(prompt, 0);
1143 		if (strcmp(password, retype) != 0) {
1144 			freezero(password, strlen(password));
1145 			logit("Mismatch; try again, EOF to quit.");
1146 			password = NULL;
1147 		}
1148 		freezero(retype, strlen(retype));
1149 	}
1150 	if ((r = sshpkt_put_cstring(ssh, password)) != 0 ||
1151 	    (r = sshpkt_add_padding(ssh, 64)) != 0 ||
1152 	    (r = sshpkt_send(ssh)) != 0)
1153 		goto out;
1154 
1155 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1156 	    &input_userauth_passwd_changereq);
1157 	r = 0;
1158  out:
1159 	if (password)
1160 		freezero(password, strlen(password));
1161 	free(info);
1162 	free(lang);
1163 	return r;
1164 }
1165 
1166 /*
1167  * Select an algorithm for publickey signatures.
1168  * Returns algorithm (caller must free) or NULL if no mutual algorithm found.
1169  *
1170  * Call with ssh==NULL to ignore server-sig-algs extension list and
1171  * only attempt with the key's base signature type.
1172  */
1173 static char *
1174 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key)
1175 {
1176 	char *allowed, *oallowed, *cp, *tmp, *alg = NULL;
1177 
1178 	/*
1179 	 * The signature algorithm will only differ from the key algorithm
1180 	 * for RSA keys/certs and when the server advertises support for
1181 	 * newer (SHA2) algorithms.
1182 	 */
1183 	if (ssh == NULL || ssh->kex->server_sig_algs == NULL ||
1184 	    (key->type != KEY_RSA && key->type != KEY_RSA_CERT) ||
1185 	    (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) {
1186 		/* Filter base key signature alg against our configuration */
1187 		return match_list(sshkey_ssh_name(key),
1188 		    options.pubkey_key_types, NULL);
1189 	}
1190 
1191 	/*
1192 	 * For RSA keys/certs, since these might have a different sig type:
1193 	 * find the first entry in PubkeyAcceptedKeyTypes of the right type
1194 	 * that also appears in the supported signature algorithms list from
1195 	 * the server.
1196 	 */
1197 	oallowed = allowed = xstrdup(options.pubkey_key_types);
1198 	while ((cp = strsep(&allowed, ",")) != NULL) {
1199 		if (sshkey_type_from_name(cp) != key->type)
1200 			continue;
1201 		tmp = match_list(sshkey_sigalg_by_name(cp),
1202 		    ssh->kex->server_sig_algs, NULL);
1203 		if (tmp != NULL)
1204 			alg = xstrdup(cp);
1205 		free(tmp);
1206 		if (alg != NULL)
1207 			break;
1208 	}
1209 	free(oallowed);
1210 	return alg;
1211 }
1212 
1213 static int
1214 identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
1215     const u_char *data, size_t datalen, u_int compat, const char *alg)
1216 {
1217 	struct sshkey *sign_key = NULL, *prv = NULL;
1218 	int r = SSH_ERR_INTERNAL_ERROR;
1219 	struct notifier_ctx *notifier = NULL;
1220 	char *fp = NULL, *pin = NULL, *prompt = NULL;
1221 
1222 	*sigp = NULL;
1223 	*lenp = 0;
1224 
1225 	/* The agent supports this key. */
1226 	if (id->key != NULL && id->agent_fd != -1) {
1227 		return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp,
1228 		    data, datalen, alg, compat);
1229 	}
1230 
1231 	/*
1232 	 * We have already loaded the private key or the private key is
1233 	 * stored in external hardware.
1234 	 */
1235 	if (id->key != NULL &&
1236 	    (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) {
1237 		sign_key = id->key;
1238 	} else {
1239 		/* Load the private key from the file. */
1240 		if ((prv = load_identity_file(id)) == NULL)
1241 			return SSH_ERR_KEY_NOT_FOUND;
1242 		if (id->key != NULL && !sshkey_equal_public(prv, id->key)) {
1243 			error("%s: private key %s contents do not match public",
1244 			   __func__, id->filename);
1245 			r = SSH_ERR_KEY_NOT_FOUND;
1246 			goto out;
1247 		}
1248 		sign_key = prv;
1249 		if (sshkey_is_sk(sign_key)) {
1250 			if ((sign_key->sk_flags &
1251 			    SSH_SK_USER_VERIFICATION_REQD)) {
1252 				xasprintf(&prompt, "Enter PIN for %s key %s: ",
1253 				    sshkey_type(sign_key), id->filename);
1254 				pin = read_passphrase(prompt, 0);
1255 			}
1256 			if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) {
1257 				/* XXX should batch mode just skip these? */
1258 				if ((fp = sshkey_fingerprint(sign_key,
1259 				    options.fingerprint_hash,
1260 				    SSH_FP_DEFAULT)) == NULL)
1261 					fatal("%s: fingerprint", __func__);
1262 				notifier = notify_start(options.batch_mode,
1263 				    "Confirm user presence for key %s %s",
1264 				    sshkey_type(sign_key), fp);
1265 				free(fp);
1266 			}
1267 		}
1268 	}
1269 	if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen,
1270 	    alg, options.sk_provider, pin, compat)) != 0) {
1271 		debug("%s: sshkey_sign: %s", __func__, ssh_err(r));
1272 		goto out;
1273 	}
1274 	/*
1275 	 * PKCS#11 tokens may not support all signature algorithms,
1276 	 * so check what we get back.
1277 	 */
1278 	if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) {
1279 		debug("%s: sshkey_check_sigtype: %s", __func__, ssh_err(r));
1280 		goto out;
1281 	}
1282 	/* success */
1283 	r = 0;
1284  out:
1285 	free(prompt);
1286 	if (pin != NULL)
1287 		freezero(pin, strlen(pin));
1288 	notify_complete(notifier);
1289 	sshkey_free(prv);
1290 	return r;
1291 }
1292 
1293 static int
1294 id_filename_matches(Identity *id, Identity *private_id)
1295 {
1296 	const char *suffixes[] = { ".pub", "-cert.pub", NULL };
1297 	size_t len = strlen(id->filename), plen = strlen(private_id->filename);
1298 	size_t i, slen;
1299 
1300 	if (strcmp(id->filename, private_id->filename) == 0)
1301 		return 1;
1302 	for (i = 0; suffixes[i]; i++) {
1303 		slen = strlen(suffixes[i]);
1304 		if (len > slen && plen == len - slen &&
1305 		    strcmp(id->filename + (len - slen), suffixes[i]) == 0 &&
1306 		    memcmp(id->filename, private_id->filename, plen) == 0)
1307 			return 1;
1308 	}
1309 	return 0;
1310 }
1311 
1312 static int
1313 sign_and_send_pubkey(struct ssh *ssh, Identity *id)
1314 {
1315 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1316 	struct sshbuf *b = NULL;
1317 	Identity *private_id, *sign_id = NULL;
1318 	u_char *signature = NULL;
1319 	size_t slen = 0, skip = 0;
1320 	int r, fallback_sigtype, sent = 0;
1321 	char *alg = NULL, *fp = NULL;
1322 	const char *loc = "";
1323 
1324 	if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
1325 	    SSH_FP_DEFAULT)) == NULL)
1326 		return 0;
1327 
1328 	debug3("%s: %s %s", __func__, sshkey_type(id->key), fp);
1329 
1330 	/*
1331 	 * If the key is an certificate, try to find a matching private key
1332 	 * and use it to complete the signature.
1333 	 * If no such private key exists, fall back to trying the certificate
1334 	 * key itself in case it has a private half already loaded.
1335 	 * This will try to set sign_id to the private key that will perform
1336 	 * the signature.
1337 	 */
1338 	if (sshkey_is_cert(id->key)) {
1339 		TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1340 			if (sshkey_equal_public(id->key, private_id->key) &&
1341 			    id->key->type != private_id->key->type) {
1342 				sign_id = private_id;
1343 				break;
1344 			}
1345 		}
1346 		/*
1347 		 * Exact key matches are preferred, but also allow
1348 		 * filename matches for non-PKCS#11/agent keys that
1349 		 * didn't load public keys. This supports the case
1350 		 * of keeping just a private key file and public
1351 		 * certificate on disk.
1352 		 */
1353 		if (sign_id == NULL &&
1354 		    !id->isprivate && id->agent_fd == -1 &&
1355 		    (id->key->flags & SSHKEY_FLAG_EXT) == 0) {
1356 			TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1357 				if (private_id->key == NULL &&
1358 				    id_filename_matches(id, private_id)) {
1359 					sign_id = private_id;
1360 					break;
1361 				}
1362 			}
1363 		}
1364 		if (sign_id != NULL) {
1365 			debug2("%s: using private key \"%s\"%s for "
1366 			    "certificate", __func__, id->filename,
1367 			    id->agent_fd != -1 ? " from agent" : "");
1368 		} else {
1369 			debug("%s: no separate private key for certificate "
1370 			    "\"%s\"", __func__, id->filename);
1371 		}
1372 	}
1373 
1374 	/*
1375 	 * If the above didn't select another identity to do the signing
1376 	 * then default to the one we started with.
1377 	 */
1378 	if (sign_id == NULL)
1379 		sign_id = id;
1380 
1381 	/* assemble and sign data */
1382 	for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) {
1383 		free(alg);
1384 		slen = 0;
1385 		signature = NULL;
1386 		if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh,
1387 		    id->key)) == NULL) {
1388 			error("%s: no mutual signature supported", __func__);
1389 			goto out;
1390 		}
1391 		debug3("%s: signing using %s %s", __func__, alg, fp);
1392 
1393 		sshbuf_free(b);
1394 		if ((b = sshbuf_new()) == NULL)
1395 			fatal("%s: sshbuf_new failed", __func__);
1396 		if (datafellows & SSH_OLD_SESSIONID) {
1397 			if ((r = sshbuf_put(b, session_id2,
1398 			    session_id2_len)) != 0) {
1399 				fatal("%s: sshbuf_put: %s",
1400 				    __func__, ssh_err(r));
1401 			}
1402 		} else {
1403 			if ((r = sshbuf_put_string(b, session_id2,
1404 			    session_id2_len)) != 0) {
1405 				fatal("%s: sshbuf_put_string: %s",
1406 				    __func__, ssh_err(r));
1407 			}
1408 		}
1409 		skip = sshbuf_len(b);
1410 		if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1411 		    (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
1412 		    (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
1413 		    (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
1414 		    (r = sshbuf_put_u8(b, 1)) != 0 ||
1415 		    (r = sshbuf_put_cstring(b, alg)) != 0 ||
1416 		    (r = sshkey_puts(id->key, b)) != 0) {
1417 			fatal("%s: assemble signed data: %s",
1418 			    __func__, ssh_err(r));
1419 		}
1420 
1421 		/* generate signature */
1422 		r = identity_sign(sign_id, &signature, &slen,
1423 		    sshbuf_ptr(b), sshbuf_len(b), datafellows, alg);
1424 		if (r == 0)
1425 			break;
1426 		else if (r == SSH_ERR_KEY_NOT_FOUND)
1427 			goto out; /* soft failure */
1428 		else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED &&
1429 		    !fallback_sigtype) {
1430 			if (sign_id->agent_fd != -1)
1431 				loc = "agent ";
1432 			else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0)
1433 				loc = "token ";
1434 			logit("%skey %s %s returned incorrect signature type",
1435 			    loc, sshkey_type(id->key), fp);
1436 			continue;
1437 		}
1438 		error("%s: signing failed for %s \"%s\"%s: %s", __func__,
1439 		    sshkey_type(sign_id->key), sign_id->filename,
1440 		    id->agent_fd != -1 ? " from agent" : "", ssh_err(r));
1441 		goto out;
1442 	}
1443 	if (slen == 0 || signature == NULL) /* shouldn't happen */
1444 		fatal("%s: no signature", __func__);
1445 
1446 	/* append signature */
1447 	if ((r = sshbuf_put_string(b, signature, slen)) != 0)
1448 		fatal("%s: append signature: %s", __func__, ssh_err(r));
1449 
1450 #ifdef DEBUG_PK
1451 	sshbuf_dump(b, stderr);
1452 #endif
1453 	/* skip session id and packet type */
1454 	if ((r = sshbuf_consume(b, skip + 1)) != 0)
1455 		fatal("%s: consume: %s", __func__, ssh_err(r));
1456 
1457 	/* put remaining data from buffer into packet */
1458 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1459 	    (r = sshpkt_putb(ssh, b)) != 0 ||
1460 	    (r = sshpkt_send(ssh)) != 0)
1461 		fatal("%s: enqueue request: %s", __func__, ssh_err(r));
1462 
1463 	/* success */
1464 	sent = 1;
1465 
1466  out:
1467 	free(fp);
1468 	free(alg);
1469 	sshbuf_free(b);
1470 	freezero(signature, slen);
1471 	return sent;
1472 }
1473 
1474 static int
1475 send_pubkey_test(struct ssh *ssh, Identity *id)
1476 {
1477 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1478 	u_char *blob = NULL;
1479 	char *alg = NULL;
1480 	size_t bloblen;
1481 	u_int have_sig = 0;
1482 	int sent = 0, r;
1483 
1484 	if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) {
1485 		debug("%s: no mutual signature algorithm", __func__);
1486 		goto out;
1487 	}
1488 
1489 	if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) {
1490 		/* we cannot handle this key */
1491 		debug3("%s: cannot handle key", __func__);
1492 		goto out;
1493 	}
1494 	/* register callback for USERAUTH_PK_OK message */
1495 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1496 
1497 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1498 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1499 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1500 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1501 	    (r = sshpkt_put_u8(ssh, have_sig)) != 0 ||
1502 	    (r = sshpkt_put_cstring(ssh, alg)) != 0 ||
1503 	    (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 ||
1504 	    (r = sshpkt_send(ssh)) != 0)
1505 		fatal("%s: %s", __func__, ssh_err(r));
1506 	sent = 1;
1507 
1508  out:
1509 	free(alg);
1510 	free(blob);
1511 	return sent;
1512 }
1513 
1514 static struct sshkey *
1515 load_identity_file(Identity *id)
1516 {
1517 	struct sshkey *private = NULL;
1518 	char prompt[300], *passphrase, *comment;
1519 	int r, quit = 0, i;
1520 	struct stat st;
1521 
1522 	if (stat(id->filename, &st) == -1) {
1523 		(id->userprovided ? logit : debug3)("no such identity: %s: %s",
1524 		    id->filename, strerror(errno));
1525 		return NULL;
1526 	}
1527 	snprintf(prompt, sizeof prompt,
1528 	    "Enter passphrase for key '%.100s': ", id->filename);
1529 	for (i = 0; i <= options.number_of_password_prompts; i++) {
1530 		if (i == 0)
1531 			passphrase = "";
1532 		else {
1533 			passphrase = read_passphrase(prompt, 0);
1534 			if (*passphrase == '\0') {
1535 				debug2("no passphrase given, try next key");
1536 				free(passphrase);
1537 				break;
1538 			}
1539 		}
1540 		switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename,
1541 		    passphrase, &private, &comment))) {
1542 		case 0:
1543 			break;
1544 		case SSH_ERR_KEY_WRONG_PASSPHRASE:
1545 			if (options.batch_mode) {
1546 				quit = 1;
1547 				break;
1548 			}
1549 			if (i != 0)
1550 				debug2("bad passphrase given, try again...");
1551 			break;
1552 		case SSH_ERR_SYSTEM_ERROR:
1553 			if (errno == ENOENT) {
1554 				debug2("Load key \"%s\": %s",
1555 				    id->filename, ssh_err(r));
1556 				quit = 1;
1557 				break;
1558 			}
1559 			/* FALLTHROUGH */
1560 		default:
1561 			error("Load key \"%s\": %s", id->filename, ssh_err(r));
1562 			quit = 1;
1563 			break;
1564 		}
1565 		if (private != NULL && sshkey_is_sk(private) &&
1566 		    options.sk_provider == NULL) {
1567 			debug("key \"%s\" is an authenticator-hosted key, "
1568 			    "but no provider specified", id->filename);
1569 			sshkey_free(private);
1570 			private = NULL;
1571 			quit = 1;
1572 		}
1573 		if (!quit && private != NULL && id->agent_fd == -1 &&
1574 		    !(id->key && id->isprivate))
1575 			maybe_add_key_to_agent(id->filename, private, comment,
1576 			    passphrase);
1577 		if (i > 0)
1578 			freezero(passphrase, strlen(passphrase));
1579 		free(comment);
1580 		if (private != NULL || quit)
1581 			break;
1582 	}
1583 	return private;
1584 }
1585 
1586 static int
1587 key_type_allowed_by_config(struct sshkey *key)
1588 {
1589 	if (match_pattern_list(sshkey_ssh_name(key),
1590 	    options.pubkey_key_types, 0) == 1)
1591 		return 1;
1592 
1593 	/* RSA keys/certs might be allowed by alternate signature types */
1594 	switch (key->type) {
1595 	case KEY_RSA:
1596 		if (match_pattern_list("rsa-sha2-512",
1597 		    options.pubkey_key_types, 0) == 1)
1598 			return 1;
1599 		if (match_pattern_list("rsa-sha2-256",
1600 		    options.pubkey_key_types, 0) == 1)
1601 			return 1;
1602 		break;
1603 	case KEY_RSA_CERT:
1604 		if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com",
1605 		    options.pubkey_key_types, 0) == 1)
1606 			return 1;
1607 		if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com",
1608 		    options.pubkey_key_types, 0) == 1)
1609 			return 1;
1610 		break;
1611 	}
1612 	return 0;
1613 }
1614 
1615 
1616 /*
1617  * try keys in the following order:
1618  * 	1. certificates listed in the config file
1619  * 	2. other input certificates
1620  *	3. agent keys that are found in the config file
1621  *	4. other agent keys
1622  *	5. keys that are only listed in the config file
1623  */
1624 static void
1625 pubkey_prepare(Authctxt *authctxt)
1626 {
1627 	struct identity *id, *id2, *tmp;
1628 	struct idlist agent, files, *preferred;
1629 	struct sshkey *key;
1630 	int agent_fd = -1, i, r, found;
1631 	size_t j;
1632 	struct ssh_identitylist *idlist;
1633 	char *ident;
1634 
1635 	TAILQ_INIT(&agent);	/* keys from the agent */
1636 	TAILQ_INIT(&files);	/* keys from the config file */
1637 	preferred = &authctxt->keys;
1638 	TAILQ_INIT(preferred);	/* preferred order of keys */
1639 
1640 	/* list of keys stored in the filesystem and PKCS#11 */
1641 	for (i = 0; i < options.num_identity_files; i++) {
1642 		key = options.identity_keys[i];
1643 		if (key && key->cert &&
1644 		    key->cert->type != SSH2_CERT_TYPE_USER) {
1645 			debug("%s: ignoring certificate %s: not a user "
1646 			    "certificate",  __func__,
1647 			    options.identity_files[i]);
1648 			continue;
1649 		}
1650 		if (key && sshkey_is_sk(key) && options.sk_provider == NULL) {
1651 			debug("%s: ignoring authenticator-hosted key %s as no "
1652 			    "SecurityKeyProvider has been specified",
1653 			    __func__, options.identity_files[i]);
1654 			continue;
1655 		}
1656 		options.identity_keys[i] = NULL;
1657 		id = xcalloc(1, sizeof(*id));
1658 		id->agent_fd = -1;
1659 		id->key = key;
1660 		id->filename = xstrdup(options.identity_files[i]);
1661 		id->userprovided = options.identity_file_userprovided[i];
1662 		TAILQ_INSERT_TAIL(&files, id, next);
1663 	}
1664 	/* list of certificates specified by user */
1665 	for (i = 0; i < options.num_certificate_files; i++) {
1666 		key = options.certificates[i];
1667 		if (!sshkey_is_cert(key) || key->cert == NULL ||
1668 		    key->cert->type != SSH2_CERT_TYPE_USER) {
1669 			debug("%s: ignoring certificate %s: not a user "
1670 			    "certificate",  __func__,
1671 			    options.identity_files[i]);
1672 			continue;
1673 		}
1674 		if (key && sshkey_is_sk(key) && options.sk_provider == NULL) {
1675 			debug("%s: ignoring authenticator-hosted key "
1676 			    "certificate %s as no "
1677 			    "SecurityKeyProvider has been specified",
1678 			    __func__, options.identity_files[i]);
1679 			continue;
1680 		}
1681 		id = xcalloc(1, sizeof(*id));
1682 		id->agent_fd = -1;
1683 		id->key = key;
1684 		id->filename = xstrdup(options.certificate_files[i]);
1685 		id->userprovided = options.certificate_file_userprovided[i];
1686 		TAILQ_INSERT_TAIL(preferred, id, next);
1687 	}
1688 	/* list of keys supported by the agent */
1689 	if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) {
1690 		if (r != SSH_ERR_AGENT_NOT_PRESENT)
1691 			debug("%s: ssh_get_authentication_socket: %s",
1692 			    __func__, ssh_err(r));
1693 	} else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) {
1694 		if (r != SSH_ERR_AGENT_NO_IDENTITIES)
1695 			debug("%s: ssh_fetch_identitylist: %s",
1696 			    __func__, ssh_err(r));
1697 		close(agent_fd);
1698 	} else {
1699 		for (j = 0; j < idlist->nkeys; j++) {
1700 			found = 0;
1701 			TAILQ_FOREACH(id, &files, next) {
1702 				/*
1703 				 * agent keys from the config file are
1704 				 * preferred
1705 				 */
1706 				if (sshkey_equal(idlist->keys[j], id->key)) {
1707 					TAILQ_REMOVE(&files, id, next);
1708 					TAILQ_INSERT_TAIL(preferred, id, next);
1709 					id->agent_fd = agent_fd;
1710 					found = 1;
1711 					break;
1712 				}
1713 			}
1714 			if (!found && !options.identities_only) {
1715 				id = xcalloc(1, sizeof(*id));
1716 				/* XXX "steals" key/comment from idlist */
1717 				id->key = idlist->keys[j];
1718 				id->filename = idlist->comments[j];
1719 				idlist->keys[j] = NULL;
1720 				idlist->comments[j] = NULL;
1721 				id->agent_fd = agent_fd;
1722 				TAILQ_INSERT_TAIL(&agent, id, next);
1723 			}
1724 		}
1725 		ssh_free_identitylist(idlist);
1726 		/* append remaining agent keys */
1727 		TAILQ_CONCAT(preferred, &agent, next);
1728 		authctxt->agent_fd = agent_fd;
1729 	}
1730 	/* Prefer PKCS11 keys that are explicitly listed */
1731 	TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1732 		if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0)
1733 			continue;
1734 		found = 0;
1735 		TAILQ_FOREACH(id2, &files, next) {
1736 			if (id2->key == NULL ||
1737 			    (id2->key->flags & SSHKEY_FLAG_EXT) != 0)
1738 				continue;
1739 			if (sshkey_equal(id->key, id2->key)) {
1740 				TAILQ_REMOVE(&files, id, next);
1741 				TAILQ_INSERT_TAIL(preferred, id, next);
1742 				found = 1;
1743 				break;
1744 			}
1745 		}
1746 		/* If IdentitiesOnly set and key not found then don't use it */
1747 		if (!found && options.identities_only) {
1748 			TAILQ_REMOVE(&files, id, next);
1749 			freezero(id, sizeof(*id));
1750 		}
1751 	}
1752 	/* append remaining keys from the config file */
1753 	TAILQ_CONCAT(preferred, &files, next);
1754 	/* finally, filter by PubkeyAcceptedKeyTypes */
1755 	TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
1756 		if (id->key != NULL && !key_type_allowed_by_config(id->key)) {
1757 			debug("Skipping %s key %s - "
1758 			    "not in PubkeyAcceptedKeyTypes",
1759 			    sshkey_ssh_name(id->key), id->filename);
1760 			TAILQ_REMOVE(preferred, id, next);
1761 			sshkey_free(id->key);
1762 			free(id->filename);
1763 			memset(id, 0, sizeof(*id));
1764 			continue;
1765 		}
1766 	}
1767 	/* List the keys we plan on using */
1768 	TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
1769 		ident = format_identity(id);
1770 		debug("Will attempt key: %s", ident);
1771 		free(ident);
1772 	}
1773 	debug2("%s: done", __func__);
1774 }
1775 
1776 static void
1777 pubkey_cleanup(struct ssh *ssh)
1778 {
1779 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1780 	Identity *id;
1781 
1782 	if (authctxt->agent_fd != -1) {
1783 		ssh_close_authentication_socket(authctxt->agent_fd);
1784 		authctxt->agent_fd = -1;
1785 	}
1786 	for (id = TAILQ_FIRST(&authctxt->keys); id;
1787 	    id = TAILQ_FIRST(&authctxt->keys)) {
1788 		TAILQ_REMOVE(&authctxt->keys, id, next);
1789 		sshkey_free(id->key);
1790 		free(id->filename);
1791 		free(id);
1792 	}
1793 }
1794 
1795 static void
1796 pubkey_reset(Authctxt *authctxt)
1797 {
1798 	Identity *id;
1799 
1800 	TAILQ_FOREACH(id, &authctxt->keys, next)
1801 		id->tried = 0;
1802 }
1803 
1804 static int
1805 try_identity(Identity *id)
1806 {
1807 	if (!id->key)
1808 		return (0);
1809 	if (sshkey_type_plain(id->key->type) == KEY_RSA &&
1810 	    (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1811 		debug("Skipped %s key %s for RSA/MD5 server",
1812 		    sshkey_type(id->key), id->filename);
1813 		return (0);
1814 	}
1815 	return 1;
1816 }
1817 
1818 static int
1819 userauth_pubkey(struct ssh *ssh)
1820 {
1821 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1822 	Identity *id;
1823 	int sent = 0;
1824 	char *ident;
1825 
1826 	while ((id = TAILQ_FIRST(&authctxt->keys))) {
1827 		if (id->tried++)
1828 			return (0);
1829 		/* move key to the end of the queue */
1830 		TAILQ_REMOVE(&authctxt->keys, id, next);
1831 		TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1832 		/*
1833 		 * send a test message if we have the public key. for
1834 		 * encrypted keys we cannot do this and have to load the
1835 		 * private key instead
1836 		 */
1837 		if (id->key != NULL) {
1838 			if (try_identity(id)) {
1839 				ident = format_identity(id);
1840 				debug("Offering public key: %s", ident);
1841 				free(ident);
1842 				sent = send_pubkey_test(ssh, id);
1843 			}
1844 		} else {
1845 			debug("Trying private key: %s", id->filename);
1846 			id->key = load_identity_file(id);
1847 			if (id->key != NULL) {
1848 				if (try_identity(id)) {
1849 					id->isprivate = 1;
1850 					sent = sign_and_send_pubkey(ssh, id);
1851 				}
1852 				sshkey_free(id->key);
1853 				id->key = NULL;
1854 				id->isprivate = 0;
1855 			}
1856 		}
1857 		if (sent)
1858 			return (sent);
1859 	}
1860 	return (0);
1861 }
1862 
1863 /*
1864  * Send userauth request message specifying keyboard-interactive method.
1865  */
1866 static int
1867 userauth_kbdint(struct ssh *ssh)
1868 {
1869 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1870 	int r;
1871 
1872 	if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts)
1873 		return 0;
1874 	/* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1875 	if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) {
1876 		debug3("userauth_kbdint: disable: no info_req_seen");
1877 		ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1878 		return 0;
1879 	}
1880 
1881 	debug2("userauth_kbdint");
1882 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1883 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1884 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1885 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1886 	    (r = sshpkt_put_cstring(ssh, "")) != 0 ||		/* lang */
1887 	    (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ?
1888 	    options.kbd_interactive_devices : "")) != 0 ||
1889 	    (r = sshpkt_send(ssh)) != 0)
1890 		fatal("%s: %s", __func__, ssh_err(r));
1891 
1892 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1893 	return 1;
1894 }
1895 
1896 /*
1897  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1898  */
1899 static int
1900 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh)
1901 {
1902 	Authctxt *authctxt = ssh->authctxt;
1903 	char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL;
1904 	char *response = NULL;
1905 	u_char echo = 0;
1906 	u_int num_prompts, i;
1907 	int r;
1908 
1909 	debug2("input_userauth_info_req");
1910 
1911 	if (authctxt == NULL)
1912 		fatal("input_userauth_info_req: no authentication context");
1913 
1914 	authctxt->info_req_seen = 1;
1915 
1916 	if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 ||
1917 	    (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 ||
1918 	    (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
1919 		goto out;
1920 	if (strlen(name) > 0)
1921 		logit("%s", name);
1922 	if (strlen(inst) > 0)
1923 		logit("%s", inst);
1924 
1925 	if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0)
1926 		goto out;
1927 	/*
1928 	 * Begin to build info response packet based on prompts requested.
1929 	 * We commit to providing the correct number of responses, so if
1930 	 * further on we run into a problem that prevents this, we have to
1931 	 * be sure and clean this up and send a correct error response.
1932 	 */
1933 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 ||
1934 	    (r = sshpkt_put_u32(ssh, num_prompts)) != 0)
1935 		goto out;
1936 
1937 	debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1938 	for (i = 0; i < num_prompts; i++) {
1939 		if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 ||
1940 		    (r = sshpkt_get_u8(ssh, &echo)) != 0)
1941 			goto out;
1942 		response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1943 		if ((r = sshpkt_put_cstring(ssh, response)) != 0)
1944 			goto out;
1945 		freezero(response, strlen(response));
1946 		free(prompt);
1947 		response = prompt = NULL;
1948 	}
1949 	/* done with parsing incoming message. */
1950 	if ((r = sshpkt_get_end(ssh)) != 0 ||
1951 	    (r = sshpkt_add_padding(ssh, 64)) != 0)
1952 		goto out;
1953 	r = sshpkt_send(ssh);
1954  out:
1955 	if (response)
1956 		freezero(response, strlen(response));
1957 	free(prompt);
1958 	free(name);
1959 	free(inst);
1960 	free(lang);
1961 	return r;
1962 }
1963 
1964 static int
1965 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
1966     const u_char *data, size_t datalen)
1967 {
1968 	struct sshbuf *b;
1969 	struct stat st;
1970 	pid_t pid;
1971 	int r, to[2], from[2], status;
1972 	int sock = ssh_packet_get_connection_in(ssh);
1973 	u_char rversion = 0, version = 2;
1974 	void (*osigchld)(int);
1975 
1976 	*sigp = NULL;
1977 	*lenp = 0;
1978 
1979 	if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) {
1980 		error("%s: not installed: %s", __func__, strerror(errno));
1981 		return -1;
1982 	}
1983 	if (fflush(stdout) != 0) {
1984 		error("%s: fflush: %s", __func__, strerror(errno));
1985 		return -1;
1986 	}
1987 	if (pipe(to) == -1) {
1988 		error("%s: pipe: %s", __func__, strerror(errno));
1989 		return -1;
1990 	}
1991 	if (pipe(from) == -1) {
1992 		error("%s: pipe: %s", __func__, strerror(errno));
1993 		return -1;
1994 	}
1995 	if ((pid = fork()) == -1) {
1996 		error("%s: fork: %s", __func__, strerror(errno));
1997 		return -1;
1998 	}
1999 	osigchld = ssh_signal(SIGCHLD, SIG_DFL);
2000 	if (pid == 0) {
2001 		close(from[0]);
2002 		if (dup2(from[1], STDOUT_FILENO) == -1)
2003 			fatal("%s: dup2: %s", __func__, strerror(errno));
2004 		close(to[1]);
2005 		if (dup2(to[0], STDIN_FILENO) == -1)
2006 			fatal("%s: dup2: %s", __func__, strerror(errno));
2007 		close(from[1]);
2008 		close(to[0]);
2009 
2010 		if (dup2(sock, STDERR_FILENO + 1) == -1)
2011 			fatal("%s: dup2: %s", __func__, strerror(errno));
2012 		sock = STDERR_FILENO + 1;
2013 		fcntl(sock, F_SETFD, 0);	/* keep the socket on exec */
2014 		closefrom(sock + 1);
2015 
2016 		debug3("%s: [child] pid=%ld, exec %s",
2017 		    __func__, (long)getpid(), _PATH_SSH_KEY_SIGN);
2018 		execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL);
2019 		fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN,
2020 		    strerror(errno));
2021 	}
2022 	close(from[1]);
2023 	close(to[0]);
2024 	sock = STDERR_FILENO + 1;
2025 
2026 	if ((b = sshbuf_new()) == NULL)
2027 		fatal("%s: sshbuf_new failed", __func__);
2028 	/* send # of sock, data to be signed */
2029 	if ((r = sshbuf_put_u32(b, sock)) != 0 ||
2030 	    (r = sshbuf_put_string(b, data, datalen)) != 0)
2031 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
2032 	if (ssh_msg_send(to[1], version, b) == -1)
2033 		fatal("%s: couldn't send request", __func__);
2034 	sshbuf_reset(b);
2035 	r = ssh_msg_recv(from[0], b);
2036 	close(from[0]);
2037 	close(to[1]);
2038 	if (r < 0) {
2039 		error("%s: no reply", __func__);
2040 		goto fail;
2041 	}
2042 
2043 	errno = 0;
2044 	while (waitpid(pid, &status, 0) == -1) {
2045 		if (errno != EINTR) {
2046 			error("%s: waitpid %ld: %s",
2047 			    __func__, (long)pid, strerror(errno));
2048 			goto fail;
2049 		}
2050 	}
2051 	if (!WIFEXITED(status)) {
2052 		error("%s: exited abnormally", __func__);
2053 		goto fail;
2054 	}
2055 	if (WEXITSTATUS(status) != 0) {
2056 		error("%s: exited with status %d",
2057 		    __func__, WEXITSTATUS(status));
2058 		goto fail;
2059 	}
2060 	if ((r = sshbuf_get_u8(b, &rversion)) != 0) {
2061 		error("%s: buffer error: %s", __func__, ssh_err(r));
2062 		goto fail;
2063 	}
2064 	if (rversion != version) {
2065 		error("%s: bad version", __func__);
2066 		goto fail;
2067 	}
2068 	if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) {
2069 		error("%s: buffer error: %s", __func__, ssh_err(r));
2070  fail:
2071 		ssh_signal(SIGCHLD, osigchld);
2072 		sshbuf_free(b);
2073 		return -1;
2074 	}
2075 	ssh_signal(SIGCHLD, osigchld);
2076 	sshbuf_free(b);
2077 
2078 	return 0;
2079 }
2080 
2081 static int
2082 userauth_hostbased(struct ssh *ssh)
2083 {
2084 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
2085 	struct sshkey *private = NULL;
2086 	struct sshbuf *b = NULL;
2087 	u_char *sig = NULL, *keyblob = NULL;
2088 	char *fp = NULL, *chost = NULL, *lname = NULL;
2089 	size_t siglen = 0, keylen = 0;
2090 	int i, r, success = 0;
2091 
2092 	if (authctxt->ktypes == NULL) {
2093 		authctxt->oktypes = xstrdup(options.hostbased_key_types);
2094 		authctxt->ktypes = authctxt->oktypes;
2095 	}
2096 
2097 	/*
2098 	 * Work through each listed type pattern in HostbasedKeyTypes,
2099 	 * trying each hostkey that matches the type in turn.
2100 	 */
2101 	for (;;) {
2102 		if (authctxt->active_ktype == NULL)
2103 			authctxt->active_ktype = strsep(&authctxt->ktypes, ",");
2104 		if (authctxt->active_ktype == NULL ||
2105 		    *authctxt->active_ktype == '\0')
2106 			break;
2107 		debug3("%s: trying key type %s", __func__,
2108 		    authctxt->active_ktype);
2109 
2110 		/* check for a useful key */
2111 		private = NULL;
2112 		for (i = 0; i < authctxt->sensitive->nkeys; i++) {
2113 			if (authctxt->sensitive->keys[i] == NULL ||
2114 			    authctxt->sensitive->keys[i]->type == KEY_UNSPEC)
2115 				continue;
2116 			if (match_pattern_list(
2117 			    sshkey_ssh_name(authctxt->sensitive->keys[i]),
2118 			    authctxt->active_ktype, 0) != 1)
2119 				continue;
2120 			/* we take and free the key */
2121 			private = authctxt->sensitive->keys[i];
2122 			authctxt->sensitive->keys[i] = NULL;
2123 			break;
2124 		}
2125 		/* Found one */
2126 		if (private != NULL)
2127 			break;
2128 		/* No more keys of this type; advance */
2129 		authctxt->active_ktype = NULL;
2130 	}
2131 	if (private == NULL) {
2132 		free(authctxt->oktypes);
2133 		authctxt->oktypes = authctxt->ktypes = NULL;
2134 		authctxt->active_ktype = NULL;
2135 		debug("No more client hostkeys for hostbased authentication.");
2136 		goto out;
2137 	}
2138 
2139 	if ((fp = sshkey_fingerprint(private, options.fingerprint_hash,
2140 	    SSH_FP_DEFAULT)) == NULL) {
2141 		error("%s: sshkey_fingerprint failed", __func__);
2142 		goto out;
2143 	}
2144 	debug("%s: trying hostkey %s %s",
2145 	    __func__, sshkey_ssh_name(private), fp);
2146 
2147 	/* figure out a name for the client host */
2148 	lname = get_local_name(ssh_packet_get_connection_in(ssh));
2149 	if (lname == NULL) {
2150 		error("%s: cannot get local ipaddr/name", __func__);
2151 		goto out;
2152 	}
2153 
2154 	/* XXX sshbuf_put_stringf? */
2155 	xasprintf(&chost, "%s.", lname);
2156 	debug2("%s: chost %s", __func__, chost);
2157 
2158 	/* construct data */
2159 	if ((b = sshbuf_new()) == NULL) {
2160 		error("%s: sshbuf_new failed", __func__);
2161 		goto out;
2162 	}
2163 	if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) {
2164 		error("%s: sshkey_to_blob: %s", __func__, ssh_err(r));
2165 		goto out;
2166 	}
2167 	if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 ||
2168 	    (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
2169 	    (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
2170 	    (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
2171 	    (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
2172 	    (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 ||
2173 	    (r = sshbuf_put_string(b, keyblob, keylen)) != 0 ||
2174 	    (r = sshbuf_put_cstring(b, chost)) != 0 ||
2175 	    (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) {
2176 		error("%s: buffer error: %s", __func__, ssh_err(r));
2177 		goto out;
2178 	}
2179 
2180 #ifdef DEBUG_PK
2181 	sshbuf_dump(b, stderr);
2182 #endif
2183 	if ((r = ssh_keysign(ssh, private, &sig, &siglen,
2184 	    sshbuf_ptr(b), sshbuf_len(b))) != 0) {
2185 		error("sign using hostkey %s %s failed",
2186 		    sshkey_ssh_name(private), fp);
2187 		goto out;
2188 	}
2189 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
2190 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
2191 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
2192 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
2193 	    (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 ||
2194 	    (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 ||
2195 	    (r = sshpkt_put_cstring(ssh, chost)) != 0 ||
2196 	    (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 ||
2197 	    (r = sshpkt_put_string(ssh, sig, siglen)) != 0 ||
2198 	    (r = sshpkt_send(ssh)) != 0) {
2199 		error("%s: packet error: %s", __func__, ssh_err(r));
2200 		goto out;
2201 	}
2202 	success = 1;
2203 
2204  out:
2205 	if (sig != NULL)
2206 		freezero(sig, siglen);
2207 	free(keyblob);
2208 	free(lname);
2209 	free(fp);
2210 	free(chost);
2211 	sshkey_free(private);
2212 	sshbuf_free(b);
2213 
2214 	return success;
2215 }
2216 
2217 /* find auth method */
2218 
2219 /*
2220  * given auth method name, if configurable options permit this method fill
2221  * in auth_ident field and return true, otherwise return false.
2222  */
2223 static int
2224 authmethod_is_enabled(Authmethod *method)
2225 {
2226 	if (method == NULL)
2227 		return 0;
2228 	/* return false if options indicate this method is disabled */
2229 	if  (method->enabled == NULL || *method->enabled == 0)
2230 		return 0;
2231 	/* return false if batch mode is enabled but method needs interactive mode */
2232 	if  (method->batch_flag != NULL && *method->batch_flag != 0)
2233 		return 0;
2234 	return 1;
2235 }
2236 
2237 static Authmethod *
2238 authmethod_lookup(const char *name)
2239 {
2240 	Authmethod *method = NULL;
2241 	if (name != NULL)
2242 		for (method = authmethods; method->name != NULL; method++)
2243 			if (strcmp(name, method->name) == 0)
2244 				return method;
2245 	debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
2246 	return NULL;
2247 }
2248 
2249 /* XXX internal state */
2250 static Authmethod *current = NULL;
2251 static char *supported = NULL;
2252 static char *preferred = NULL;
2253 
2254 /*
2255  * Given the authentication method list sent by the server, return the
2256  * next method we should try.  If the server initially sends a nil list,
2257  * use a built-in default list.
2258  */
2259 static Authmethod *
2260 authmethod_get(char *authlist)
2261 {
2262 	char *name = NULL;
2263 	u_int next;
2264 
2265 	/* Use a suitable default if we're passed a nil list.  */
2266 	if (authlist == NULL || strlen(authlist) == 0)
2267 		authlist = options.preferred_authentications;
2268 
2269 	if (supported == NULL || strcmp(authlist, supported) != 0) {
2270 		debug3("start over, passed a different list %s", authlist);
2271 		free(supported);
2272 		supported = xstrdup(authlist);
2273 		preferred = options.preferred_authentications;
2274 		debug3("preferred %s", preferred);
2275 		current = NULL;
2276 	} else if (current != NULL && authmethod_is_enabled(current))
2277 		return current;
2278 
2279 	for (;;) {
2280 		if ((name = match_list(preferred, supported, &next)) == NULL) {
2281 			debug("No more authentication methods to try.");
2282 			current = NULL;
2283 			return NULL;
2284 		}
2285 		preferred += next;
2286 		debug3("authmethod_lookup %s", name);
2287 		debug3("remaining preferred: %s", preferred);
2288 		if ((current = authmethod_lookup(name)) != NULL &&
2289 		    authmethod_is_enabled(current)) {
2290 			debug3("authmethod_is_enabled %s", name);
2291 			debug("Next authentication method: %s", name);
2292 			free(name);
2293 			return current;
2294 		}
2295 		free(name);
2296 	}
2297 }
2298 
2299 static char *
2300 authmethods_get(void)
2301 {
2302 	Authmethod *method = NULL;
2303 	struct sshbuf *b;
2304 	char *list;
2305 	int r;
2306 
2307 	if ((b = sshbuf_new()) == NULL)
2308 		fatal("%s: sshbuf_new failed", __func__);
2309 	for (method = authmethods; method->name != NULL; method++) {
2310 		if (authmethod_is_enabled(method)) {
2311 			if ((r = sshbuf_putf(b, "%s%s",
2312 			    sshbuf_len(b) ? "," : "", method->name)) != 0)
2313 				fatal("%s: buffer error: %s",
2314 				    __func__, ssh_err(r));
2315 		}
2316 	}
2317 	if ((list = sshbuf_dup_string(b)) == NULL)
2318 		fatal("%s: sshbuf_dup_string failed", __func__);
2319 	sshbuf_free(b);
2320 	return list;
2321 }
2322