xref: /openbsd-src/usr.bin/ssh/sshconnect2.c (revision 46035553bfdd96e63c94e32da0210227ec2e3cf1)
1 /* $OpenBSD: sshconnect2.c,v 1.340 2020/12/29 00:59:15 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 <sys/types.h>
28 #include <sys/socket.h>
29 #include <sys/wait.h>
30 #include <sys/queue.h>
31 #include <sys/stat.h>
32 
33 #include <errno.h>
34 #include <fcntl.h>
35 #include <limits.h>
36 #include <netdb.h>
37 #include <stdio.h>
38 #include <string.h>
39 #include <stdarg.h>
40 #include <signal.h>
41 #include <pwd.h>
42 #include <unistd.h>
43 #include <vis.h>
44 
45 #include "xmalloc.h"
46 #include "ssh.h"
47 #include "ssh2.h"
48 #include "sshbuf.h"
49 #include "packet.h"
50 #include "compat.h"
51 #include "cipher.h"
52 #include "sshkey.h"
53 #include "kex.h"
54 #include "myproposal.h"
55 #include "sshconnect.h"
56 #include "authfile.h"
57 #include "dh.h"
58 #include "authfd.h"
59 #include "log.h"
60 #include "misc.h"
61 #include "readconf.h"
62 #include "match.h"
63 #include "dispatch.h"
64 #include "canohost.h"
65 #include "msg.h"
66 #include "pathnames.h"
67 #include "uidswap.h"
68 #include "hostfile.h"
69 #include "ssherr.h"
70 #include "utf8.h"
71 #include "ssh-sk.h"
72 #include "sk-api.h"
73 
74 #ifdef GSSAPI
75 #include "ssh-gss.h"
76 #endif
77 
78 /* import */
79 extern char *client_version_string;
80 extern char *server_version_string;
81 extern Options options;
82 
83 /*
84  * SSH2 key exchange
85  */
86 
87 u_char *session_id2 = NULL;
88 u_int session_id2_len = 0;
89 
90 static char *xxx_host;
91 static struct sockaddr *xxx_hostaddr;
92 static const struct ssh_conn_info *xxx_conn_info;
93 
94 static int
95 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh)
96 {
97 	if (verify_host_key(xxx_host, xxx_hostaddr, hostkey,
98 	    xxx_conn_info) == -1)
99 		fatal("Host key verification failed.");
100 	return 0;
101 }
102 
103 /* Returns the first item from a comma-separated algorithm list */
104 static char *
105 first_alg(const char *algs)
106 {
107 	char *ret, *cp;
108 
109 	ret = xstrdup(algs);
110 	if ((cp = strchr(ret, ',')) != NULL)
111 		*cp = '\0';
112 	return ret;
113 }
114 
115 static char *
116 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port,
117     const struct ssh_conn_info *cinfo)
118 {
119 	char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL;
120 	char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL;
121 	size_t maxlen;
122 	struct hostkeys *hostkeys = NULL;
123 	int ktype;
124 	u_int i;
125 
126 	/* Find all hostkeys for this hostname */
127 	get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
128 	hostkeys = init_hostkeys();
129 	for (i = 0; i < options.num_user_hostfiles; i++)
130 		load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0);
131 	for (i = 0; i < options.num_system_hostfiles; i++) {
132 		load_hostkeys(hostkeys, hostname,
133 		    options.system_hostfiles[i], 0);
134 	}
135 	if (options.known_hosts_command != NULL) {
136 		load_hostkeys_command(hostkeys, options.known_hosts_command,
137 		    "ORDER", cinfo, NULL, host);
138 	}
139 	/*
140 	 * If a plain public key exists that matches the type of the best
141 	 * preference HostkeyAlgorithms, then use the whole list as is.
142 	 * Note that we ignore whether the best preference algorithm is a
143 	 * certificate type, as sshconnect.c will downgrade certs to
144 	 * plain keys if necessary.
145 	 */
146 	best = first_alg(options.hostkeyalgorithms);
147 	if (lookup_key_in_hostkeys_by_type(hostkeys,
148 	    sshkey_type_plain(sshkey_type_from_name(best)),
149 	    sshkey_ecdsa_nid_from_name(best), NULL)) {
150 		debug3_f("have matching best-preference key type %s, "
151 		    "using HostkeyAlgorithms verbatim", best);
152 		ret = xstrdup(options.hostkeyalgorithms);
153 		goto out;
154 	}
155 
156 	/*
157 	 * Otherwise, prefer the host key algorithms that match known keys
158 	 * while keeping the ordering of HostkeyAlgorithms as much as possible.
159 	 */
160 	oavail = avail = xstrdup(options.hostkeyalgorithms);
161 	maxlen = strlen(avail) + 1;
162 	first = xmalloc(maxlen);
163 	last = xmalloc(maxlen);
164 	*first = *last = '\0';
165 
166 #define ALG_APPEND(to, from) \
167 	do { \
168 		if (*to != '\0') \
169 			strlcat(to, ",", maxlen); \
170 		strlcat(to, from, maxlen); \
171 	} while (0)
172 
173 	while ((alg = strsep(&avail, ",")) && *alg != '\0') {
174 		if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
175 			fatal_f("unknown alg %s", alg);
176 		/*
177 		 * If we have a @cert-authority marker in known_hosts then
178 		 * prefer all certificate algorithms.
179 		 */
180 		if (sshkey_type_is_cert(ktype) &&
181 		    lookup_marker_in_hostkeys(hostkeys, MRK_CA)) {
182 			ALG_APPEND(first, alg);
183 			continue;
184 		}
185 		/* If the key appears in known_hosts then prefer it */
186 		if (lookup_key_in_hostkeys_by_type(hostkeys,
187 		    sshkey_type_plain(ktype),
188 		    sshkey_ecdsa_nid_from_name(alg), NULL)) {
189 			ALG_APPEND(first, alg);
190 			continue;
191 		}
192 		/* Otherwise, put it last */
193 		ALG_APPEND(last, alg);
194 	}
195 #undef ALG_APPEND
196 	xasprintf(&ret, "%s%s%s", first,
197 	    (*first == '\0' || *last == '\0') ? "" : ",", last);
198 	if (*first != '\0')
199 		debug3_f("prefer hostkeyalgs: %s", first);
200 	else
201 		debug3_f("no algorithms matched; accept original");
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     const struct ssh_conn_info *cinfo)
216 {
217 	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
218 	char *s, *all_key;
219 	int r, use_known_hosts_order = 0;
220 
221 	xxx_host = host;
222 	xxx_hostaddr = hostaddr;
223 	xxx_conn_info = cinfo;
224 
225 	/*
226 	 * If the user has not specified HostkeyAlgorithms, or has only
227 	 * appended or removed algorithms from that list then prefer algorithms
228 	 * that are in the list that are supported by known_hosts keys.
229 	 */
230 	if (options.hostkeyalgorithms == NULL ||
231 	    options.hostkeyalgorithms[0] == '-' ||
232 	    options.hostkeyalgorithms[0] == '+')
233 		use_known_hosts_order = 1;
234 
235 	/* Expand or fill in HostkeyAlgorithms */
236 	all_key = sshkey_alg_list(0, 0, 1, ',');
237 	if ((r = kex_assemble_names(&options.hostkeyalgorithms,
238 	    kex_default_pk_alg(), all_key)) != 0)
239 		fatal_fr(r, "kex_assemble_namelist");
240 	free(all_key);
241 
242 	if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL)
243 		fatal_f("kex_names_cat");
244 	myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s);
245 	myproposal[PROPOSAL_ENC_ALGS_CTOS] =
246 	    compat_cipher_proposal(options.ciphers);
247 	myproposal[PROPOSAL_ENC_ALGS_STOC] =
248 	    compat_cipher_proposal(options.ciphers);
249 	myproposal[PROPOSAL_COMP_ALGS_CTOS] =
250 	    myproposal[PROPOSAL_COMP_ALGS_STOC] =
251 	    (char *)compression_alg_list(options.compression);
252 	myproposal[PROPOSAL_MAC_ALGS_CTOS] =
253 	    myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
254 	if (use_known_hosts_order) {
255 		/* Query known_hosts and prefer algorithms that appear there */
256 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
257 		    compat_pkalg_proposal(
258 		    order_hostkeyalgs(host, hostaddr, port, cinfo));
259 	} else {
260 		/* Use specified HostkeyAlgorithms exactly */
261 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
262 		    compat_pkalg_proposal(options.hostkeyalgorithms);
263 	}
264 
265 	if (options.rekey_limit || options.rekey_interval)
266 		ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
267 		    options.rekey_interval);
268 
269 	/* start key exchange */
270 	if ((r = kex_setup(ssh, myproposal)) != 0)
271 		fatal_r(r, "kex_setup");
272 #ifdef WITH_OPENSSL
273 	ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client;
274 	ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client;
275 	ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client;
276 	ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client;
277 	ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client;
278 	ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
279 	ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
280 	ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client;
281 #endif
282 	ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client;
283 	ssh->kex->kex[KEX_KEM_SNTRUP761X25519_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_r(r, "kex_prop2buf");
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_fr(r, "send packet");
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_f("internal error: cannot send userauth none request");
472 	}
473 
474 	if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 ||
475 	    (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 ||
476 	    (r = sshpkt_send(ssh)) != 0)
477 		fatal_fr(r, "send packet");
478 
479 	ssh->authctxt = &authctxt;
480 	ssh_dispatch_init(ssh, &input_userauth_error);
481 	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info);
482 	ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept);
483 	ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success);	/* loop until success */
484 	pubkey_cleanup(ssh);
485 	ssh->authctxt = NULL;
486 
487 	ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
488 
489 	if (!authctxt.success)
490 		fatal("Authentication failed.");
491 	debug("Authentication succeeded (%s).", authctxt.method->name);
492 }
493 
494 /* ARGSUSED */
495 static int
496 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh)
497 {
498 	int r;
499 
500 	if (ssh_packet_remaining(ssh) > 0) {
501 		char *reply;
502 
503 		if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0)
504 			goto out;
505 		debug2("service_accept: %s", reply);
506 		free(reply);
507 	} else {
508 		debug2("buggy server: service_accept w/o service");
509 	}
510 	if ((r = sshpkt_get_end(ssh)) != 0)
511 		goto out;
512 	debug("SSH2_MSG_SERVICE_ACCEPT received");
513 
514 	/* initial userauth request */
515 	userauth_none(ssh);
516 
517 	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error);
518 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
519 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
520 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
521 	r = 0;
522  out:
523 	return r;
524 }
525 
526 /* ARGSUSED */
527 static int
528 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh)
529 {
530 	return kex_input_ext_info(type, seqnr, ssh);
531 }
532 
533 void
534 userauth(struct ssh *ssh, char *authlist)
535 {
536 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
537 
538 	if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
539 		authctxt->method->cleanup(ssh);
540 
541 	free(authctxt->methoddata);
542 	authctxt->methoddata = NULL;
543 	if (authlist == NULL) {
544 		authlist = authctxt->authlist;
545 	} else {
546 		free(authctxt->authlist);
547 		authctxt->authlist = authlist;
548 	}
549 	for (;;) {
550 		Authmethod *method = authmethod_get(authlist);
551 		if (method == NULL)
552 			fatal("%s@%s: Permission denied (%s).",
553 			    authctxt->server_user, authctxt->host, authlist);
554 		authctxt->method = method;
555 
556 		/* reset the per method handler */
557 		ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN,
558 		    SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
559 
560 		/* and try new method */
561 		if (method->userauth(ssh) != 0) {
562 			debug2("we sent a %s packet, wait for reply", method->name);
563 			break;
564 		} else {
565 			debug2("we did not send a packet, disable method");
566 			method->enabled = NULL;
567 		}
568 	}
569 }
570 
571 /* ARGSUSED */
572 static int
573 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh)
574 {
575 	fatal_f("bad message during authentication: type %d", type);
576 	return 0;
577 }
578 
579 /* ARGSUSED */
580 static int
581 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh)
582 {
583 	char *msg = NULL;
584 	size_t len;
585 	int r;
586 
587 	debug3_f("entering");
588 	if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 ||
589 	    (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0)
590 		goto out;
591 	if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO)
592 		fmprintf(stderr, "%s", msg);
593 	r = 0;
594  out:
595 	free(msg);
596 	return r;
597 }
598 
599 /* ARGSUSED */
600 static int
601 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh)
602 {
603 	Authctxt *authctxt = ssh->authctxt;
604 
605 	if (authctxt == NULL)
606 		fatal_f("no authentication context");
607 	free(authctxt->authlist);
608 	authctxt->authlist = NULL;
609 	if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
610 		authctxt->method->cleanup(ssh);
611 	free(authctxt->methoddata);
612 	authctxt->methoddata = NULL;
613 	authctxt->success = 1;			/* break out */
614 	return 0;
615 }
616 
617 #if 0
618 static int
619 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh)
620 {
621 	Authctxt *authctxt = ssh->authctxt;
622 
623 	if (authctxt == NULL)
624 		fatal_f("no authentication context");
625 
626 	fatal("Unexpected authentication success during %s.",
627 	    authctxt->method->name);
628 	return 0;
629 }
630 #endif
631 
632 /* ARGSUSED */
633 static int
634 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh)
635 {
636 	Authctxt *authctxt = ssh->authctxt;
637 	char *authlist = NULL;
638 	u_char partial;
639 
640 	if (authctxt == NULL)
641 		fatal("input_userauth_failure: no authentication context");
642 
643 	if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 ||
644 	    sshpkt_get_u8(ssh, &partial) != 0 ||
645 	    sshpkt_get_end(ssh) != 0)
646 		goto out;
647 
648 	if (partial != 0) {
649 		verbose("Authenticated with partial success.");
650 		/* reset state */
651 		pubkey_reset(authctxt);
652 	}
653 	debug("Authentications that can continue: %s", authlist);
654 
655 	userauth(ssh, authlist);
656 	authlist = NULL;
657  out:
658 	free(authlist);
659 	return 0;
660 }
661 
662 /*
663  * Format an identity for logging including filename, key type, fingerprint
664  * and location (agent, etc.). Caller must free.
665  */
666 static char *
667 format_identity(Identity *id)
668 {
669 	char *fp = NULL, *ret = NULL;
670 	const char *note = "";
671 
672 	if (id->key != NULL) {
673 	     fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
674 		    SSH_FP_DEFAULT);
675 	}
676 	if (id->key) {
677 		if ((id->key->flags & SSHKEY_FLAG_EXT) != 0)
678 			note = " token";
679 		else if (sshkey_is_sk(id->key))
680 			note = " authenticator";
681 	}
682 	xasprintf(&ret, "%s %s%s%s%s%s%s",
683 	    id->filename,
684 	    id->key ? sshkey_type(id->key) : "", id->key ? " " : "",
685 	    fp ? fp : "",
686 	    id->userprovided ? " explicit" : "", note,
687 	    id->agent_fd != -1 ? " agent" : "");
688 	free(fp);
689 	return ret;
690 }
691 
692 /* ARGSUSED */
693 static int
694 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh)
695 {
696 	Authctxt *authctxt = ssh->authctxt;
697 	struct sshkey *key = NULL;
698 	Identity *id = NULL;
699 	int pktype, found = 0, sent = 0;
700 	size_t blen;
701 	char *pkalg = NULL, *fp = NULL, *ident = NULL;
702 	u_char *pkblob = NULL;
703 	int r;
704 
705 	if (authctxt == NULL)
706 		fatal("input_userauth_pk_ok: no authentication context");
707 
708 	if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 ||
709 	    (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 ||
710 	    (r = sshpkt_get_end(ssh)) != 0)
711 		goto done;
712 
713 	if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) {
714 		debug_f("server sent unknown pkalg %s", pkalg);
715 		goto done;
716 	}
717 	if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
718 		debug_r(r, "no key from blob. pkalg %s", pkalg);
719 		goto done;
720 	}
721 	if (key->type != pktype) {
722 		error("input_userauth_pk_ok: type mismatch "
723 		    "for decoded key (received %d, expected %d)",
724 		    key->type, pktype);
725 		goto done;
726 	}
727 
728 	/*
729 	 * search keys in the reverse order, because last candidate has been
730 	 * moved to the end of the queue.  this also avoids confusion by
731 	 * duplicate keys
732 	 */
733 	TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
734 		if (sshkey_equal(key, id->key)) {
735 			found = 1;
736 			break;
737 		}
738 	}
739 	if (!found || id == NULL) {
740 		fp = sshkey_fingerprint(key, options.fingerprint_hash,
741 		    SSH_FP_DEFAULT);
742 		error_f("server replied with unknown key: %s %s",
743 		    sshkey_type(key), fp == NULL ? "<ERROR>" : fp);
744 		goto done;
745 	}
746 	ident = format_identity(id);
747 	debug("Server accepts key: %s", ident);
748 	sent = sign_and_send_pubkey(ssh, id);
749 	r = 0;
750  done:
751 	sshkey_free(key);
752 	free(ident);
753 	free(fp);
754 	free(pkalg);
755 	free(pkblob);
756 
757 	/* try another method if we did not send a packet */
758 	if (r == 0 && sent == 0)
759 		userauth(ssh, NULL);
760 	return r;
761 }
762 
763 #ifdef GSSAPI
764 static int
765 userauth_gssapi(struct ssh *ssh)
766 {
767 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
768 	Gssctxt *gssctxt = NULL;
769 	OM_uint32 min;
770 	int r, ok = 0;
771 	gss_OID mech = NULL;
772 
773 	/* Try one GSSAPI method at a time, rather than sending them all at
774 	 * once. */
775 
776 	if (authctxt->gss_supported_mechs == NULL)
777 		gss_indicate_mechs(&min, &authctxt->gss_supported_mechs);
778 
779 	/* Check to see whether the mechanism is usable before we offer it */
780 	while (authctxt->mech_tried < authctxt->gss_supported_mechs->count &&
781 	    !ok) {
782 		mech = &authctxt->gss_supported_mechs->
783 		    elements[authctxt->mech_tried];
784 		/* My DER encoding requires length<128 */
785 		if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt,
786 		    mech, authctxt->host)) {
787 			ok = 1; /* Mechanism works */
788 		} else {
789 			authctxt->mech_tried++;
790 		}
791 	}
792 
793 	if (!ok || mech == NULL)
794 		return 0;
795 
796 	authctxt->methoddata=(void *)gssctxt;
797 
798 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
799 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
800 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
801 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
802 	    (r = sshpkt_put_u32(ssh, 1)) != 0 ||
803 	    (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 ||
804 	    (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 ||
805 	    (r = sshpkt_put_u8(ssh, mech->length)) != 0 ||
806 	    (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 ||
807 	    (r = sshpkt_send(ssh)) != 0)
808 		fatal_fr(r, "send packet");
809 
810 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
811 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
812 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
813 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
814 
815 	authctxt->mech_tried++; /* Move along to next candidate */
816 
817 	return 1;
818 }
819 
820 static void
821 userauth_gssapi_cleanup(struct ssh *ssh)
822 {
823 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
824 	Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata;
825 
826 	ssh_gssapi_delete_ctx(&gssctxt);
827 	authctxt->methoddata = NULL;
828 
829 	free(authctxt->gss_supported_mechs);
830 	authctxt->gss_supported_mechs = NULL;
831 }
832 
833 static OM_uint32
834 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok)
835 {
836 	Authctxt *authctxt = ssh->authctxt;
837 	Gssctxt *gssctxt = authctxt->methoddata;
838 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
839 	gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
840 	gss_buffer_desc gssbuf;
841 	OM_uint32 status, ms, flags;
842 	int r;
843 
844 	status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
845 	    recv_tok, &send_tok, &flags);
846 
847 	if (send_tok.length > 0) {
848 		u_char type = GSS_ERROR(status) ?
849 		    SSH2_MSG_USERAUTH_GSSAPI_ERRTOK :
850 		    SSH2_MSG_USERAUTH_GSSAPI_TOKEN;
851 
852 		if ((r = sshpkt_start(ssh, type)) != 0 ||
853 		    (r = sshpkt_put_string(ssh, send_tok.value,
854 		    send_tok.length)) != 0 ||
855 		    (r = sshpkt_send(ssh)) != 0)
856 			fatal_fr(r, "send %u packet", type);
857 
858 		gss_release_buffer(&ms, &send_tok);
859 	}
860 
861 	if (status == GSS_S_COMPLETE) {
862 		/* send either complete or MIC, depending on mechanism */
863 		if (!(flags & GSS_C_INTEG_FLAG)) {
864 			if ((r = sshpkt_start(ssh,
865 			    SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 ||
866 			    (r = sshpkt_send(ssh)) != 0)
867 				fatal_fr(r, "send completion");
868 		} else {
869 			struct sshbuf *b;
870 
871 			if ((b = sshbuf_new()) == NULL)
872 				fatal_f("sshbuf_new failed");
873 			ssh_gssapi_buildmic(b, authctxt->server_user,
874 			    authctxt->service, "gssapi-with-mic");
875 
876 			if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
877 				fatal_f("sshbuf_mutable_ptr failed");
878 			gssbuf.length = sshbuf_len(b);
879 
880 			status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
881 
882 			if (!GSS_ERROR(status)) {
883 				if ((r = sshpkt_start(ssh,
884 				    SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 ||
885 				    (r = sshpkt_put_string(ssh, mic.value,
886 				    mic.length)) != 0 ||
887 				    (r = sshpkt_send(ssh)) != 0)
888 					fatal_fr(r, "send MIC");
889 			}
890 
891 			sshbuf_free(b);
892 			gss_release_buffer(&ms, &mic);
893 		}
894 	}
895 
896 	return status;
897 }
898 
899 /* ARGSUSED */
900 static int
901 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh)
902 {
903 	Authctxt *authctxt = ssh->authctxt;
904 	Gssctxt *gssctxt;
905 	size_t oidlen;
906 	u_char *oidv = NULL;
907 	int r;
908 
909 	if (authctxt == NULL)
910 		fatal("input_gssapi_response: no authentication context");
911 	gssctxt = authctxt->methoddata;
912 
913 	/* Setup our OID */
914 	if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0)
915 		goto done;
916 
917 	if (oidlen <= 2 ||
918 	    oidv[0] != SSH_GSS_OIDTYPE ||
919 	    oidv[1] != oidlen - 2) {
920 		debug("Badly encoded mechanism OID received");
921 		userauth(ssh, NULL);
922 		goto ok;
923 	}
924 
925 	if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
926 		fatal("Server returned different OID than expected");
927 
928 	if ((r = sshpkt_get_end(ssh)) != 0)
929 		goto done;
930 
931 	if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) {
932 		/* Start again with next method on list */
933 		debug("Trying to start again");
934 		userauth(ssh, NULL);
935 		goto ok;
936 	}
937  ok:
938 	r = 0;
939  done:
940 	free(oidv);
941 	return r;
942 }
943 
944 /* ARGSUSED */
945 static int
946 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh)
947 {
948 	Authctxt *authctxt = ssh->authctxt;
949 	gss_buffer_desc recv_tok;
950 	u_char *p = NULL;
951 	size_t len;
952 	OM_uint32 status;
953 	int r;
954 
955 	if (authctxt == NULL)
956 		fatal("input_gssapi_response: no authentication context");
957 
958 	if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
959 	    (r = sshpkt_get_end(ssh)) != 0)
960 		goto out;
961 
962 	recv_tok.value = p;
963 	recv_tok.length = len;
964 	status = process_gssapi_token(ssh, &recv_tok);
965 
966 	/* Start again with the next method in the list */
967 	if (GSS_ERROR(status)) {
968 		userauth(ssh, NULL);
969 		/* ok */
970 	}
971 	r = 0;
972  out:
973 	free(p);
974 	return r;
975 }
976 
977 /* ARGSUSED */
978 static int
979 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh)
980 {
981 	Authctxt *authctxt = ssh->authctxt;
982 	Gssctxt *gssctxt;
983 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
984 	gss_buffer_desc recv_tok;
985 	OM_uint32 ms;
986 	u_char *p = NULL;
987 	size_t len;
988 	int r;
989 
990 	if (authctxt == NULL)
991 		fatal("input_gssapi_response: no authentication context");
992 	gssctxt = authctxt->methoddata;
993 
994 	if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
995 	    (r = sshpkt_get_end(ssh)) != 0) {
996 		free(p);
997 		return r;
998 	}
999 
1000 	/* Stick it into GSSAPI and see what it says */
1001 	recv_tok.value = p;
1002 	recv_tok.length = len;
1003 	(void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
1004 	    &recv_tok, &send_tok, NULL);
1005 	free(p);
1006 	gss_release_buffer(&ms, &send_tok);
1007 
1008 	/* Server will be returning a failed packet after this one */
1009 	return 0;
1010 }
1011 
1012 /* ARGSUSED */
1013 static int
1014 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
1015 {
1016 	char *msg = NULL;
1017 	char *lang = NULL;
1018 	int r;
1019 
1020 	if ((r = sshpkt_get_u32(ssh, NULL)) != 0 ||	/* maj */
1021 	    (r = sshpkt_get_u32(ssh, NULL)) != 0 ||	/* min */
1022 	    (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 ||
1023 	    (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
1024 		goto out;
1025 	r = sshpkt_get_end(ssh);
1026 	debug("Server GSSAPI Error:\n%s", msg);
1027  out:
1028 	free(msg);
1029 	free(lang);
1030 	return r;
1031 }
1032 #endif /* GSSAPI */
1033 
1034 static int
1035 userauth_none(struct ssh *ssh)
1036 {
1037 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1038 	int r;
1039 
1040 	/* initial userauth request */
1041 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1042 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1043 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1044 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1045 	    (r = sshpkt_send(ssh)) != 0)
1046 		fatal_fr(r, "send packet");
1047 	return 1;
1048 }
1049 
1050 static int
1051 userauth_passwd(struct ssh *ssh)
1052 {
1053 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1054 	char *password, *prompt = NULL;
1055 	const char *host = options.host_key_alias ?  options.host_key_alias :
1056 	    authctxt->host;
1057 	int r;
1058 
1059 	if (authctxt->attempt_passwd++ >= options.number_of_password_prompts)
1060 		return 0;
1061 
1062 	if (authctxt->attempt_passwd != 1)
1063 		error("Permission denied, please try again.");
1064 
1065 	xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host);
1066 	password = read_passphrase(prompt, 0);
1067 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1068 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1069 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1070 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1071 	    (r = sshpkt_put_u8(ssh, 0)) != 0 ||
1072 	    (r = sshpkt_put_cstring(ssh, password)) != 0 ||
1073 	    (r = sshpkt_add_padding(ssh, 64)) != 0 ||
1074 	    (r = sshpkt_send(ssh)) != 0)
1075 		fatal_fr(r, "send packet");
1076 
1077 	free(prompt);
1078 	if (password != NULL)
1079 		freezero(password, strlen(password));
1080 
1081 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1082 	    &input_userauth_passwd_changereq);
1083 
1084 	return 1;
1085 }
1086 
1087 /*
1088  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
1089  */
1090 /* ARGSUSED */
1091 static int
1092 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh)
1093 {
1094 	Authctxt *authctxt = ssh->authctxt;
1095 	char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL;
1096 	char prompt[256];
1097 	const char *host;
1098 	int r;
1099 
1100 	debug2("input_userauth_passwd_changereq");
1101 
1102 	if (authctxt == NULL)
1103 		fatal("input_userauth_passwd_changereq: "
1104 		    "no authentication context");
1105 	host = options.host_key_alias ? options.host_key_alias : authctxt->host;
1106 
1107 	if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 ||
1108 	    (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
1109 		goto out;
1110 	if (strlen(info) > 0)
1111 		logit("%s", info);
1112 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1113 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1114 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1115 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1116 	    (r = sshpkt_put_u8(ssh, 1)) != 0)	/* additional info */
1117 		goto out;
1118 
1119 	snprintf(prompt, sizeof(prompt),
1120 	    "Enter %.30s@%.128s's old password: ",
1121 	    authctxt->server_user, host);
1122 	password = read_passphrase(prompt, 0);
1123 	if ((r = sshpkt_put_cstring(ssh, password)) != 0)
1124 		goto out;
1125 
1126 	freezero(password, strlen(password));
1127 	password = NULL;
1128 	while (password == NULL) {
1129 		snprintf(prompt, sizeof(prompt),
1130 		    "Enter %.30s@%.128s's new password: ",
1131 		    authctxt->server_user, host);
1132 		password = read_passphrase(prompt, RP_ALLOW_EOF);
1133 		if (password == NULL) {
1134 			/* bail out */
1135 			r = 0;
1136 			goto out;
1137 		}
1138 		snprintf(prompt, sizeof(prompt),
1139 		    "Retype %.30s@%.128s's new password: ",
1140 		    authctxt->server_user, host);
1141 		retype = read_passphrase(prompt, 0);
1142 		if (strcmp(password, retype) != 0) {
1143 			freezero(password, strlen(password));
1144 			logit("Mismatch; try again, EOF to quit.");
1145 			password = NULL;
1146 		}
1147 		freezero(retype, strlen(retype));
1148 	}
1149 	if ((r = sshpkt_put_cstring(ssh, password)) != 0 ||
1150 	    (r = sshpkt_add_padding(ssh, 64)) != 0 ||
1151 	    (r = sshpkt_send(ssh)) != 0)
1152 		goto out;
1153 
1154 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1155 	    &input_userauth_passwd_changereq);
1156 	r = 0;
1157  out:
1158 	if (password)
1159 		freezero(password, strlen(password));
1160 	free(info);
1161 	free(lang);
1162 	return r;
1163 }
1164 
1165 /*
1166  * Select an algorithm for publickey signatures.
1167  * Returns algorithm (caller must free) or NULL if no mutual algorithm found.
1168  *
1169  * Call with ssh==NULL to ignore server-sig-algs extension list and
1170  * only attempt with the key's base signature type.
1171  */
1172 static char *
1173 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key)
1174 {
1175 	char *allowed, *oallowed, *cp, *tmp, *alg = NULL;
1176 
1177 	/*
1178 	 * The signature algorithm will only differ from the key algorithm
1179 	 * for RSA keys/certs and when the server advertises support for
1180 	 * newer (SHA2) algorithms.
1181 	 */
1182 	if (ssh == NULL || ssh->kex->server_sig_algs == NULL ||
1183 	    (key->type != KEY_RSA && key->type != KEY_RSA_CERT) ||
1184 	    (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) {
1185 		/* Filter base key signature alg against our configuration */
1186 		return match_list(sshkey_ssh_name(key),
1187 		    options.pubkey_key_types, NULL);
1188 	}
1189 
1190 	/*
1191 	 * For RSA keys/certs, since these might have a different sig type:
1192 	 * find the first entry in PubkeyAcceptedKeyTypes of the right type
1193 	 * that also appears in the supported signature algorithms list from
1194 	 * the server.
1195 	 */
1196 	oallowed = allowed = xstrdup(options.pubkey_key_types);
1197 	while ((cp = strsep(&allowed, ",")) != NULL) {
1198 		if (sshkey_type_from_name(cp) != key->type)
1199 			continue;
1200 		tmp = match_list(sshkey_sigalg_by_name(cp),
1201 		    ssh->kex->server_sig_algs, NULL);
1202 		if (tmp != NULL)
1203 			alg = xstrdup(cp);
1204 		free(tmp);
1205 		if (alg != NULL)
1206 			break;
1207 	}
1208 	free(oallowed);
1209 	return alg;
1210 }
1211 
1212 static int
1213 identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
1214     const u_char *data, size_t datalen, u_int compat, const char *alg)
1215 {
1216 	struct sshkey *sign_key = NULL, *prv = NULL;
1217 	int r = SSH_ERR_INTERNAL_ERROR;
1218 	struct notifier_ctx *notifier = NULL;
1219 	char *fp = NULL, *pin = NULL, *prompt = NULL;
1220 
1221 	*sigp = NULL;
1222 	*lenp = 0;
1223 
1224 	/* The agent supports this key. */
1225 	if (id->key != NULL && id->agent_fd != -1) {
1226 		return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp,
1227 		    data, datalen, alg, compat);
1228 	}
1229 
1230 	/*
1231 	 * We have already loaded the private key or the private key is
1232 	 * stored in external hardware.
1233 	 */
1234 	if (id->key != NULL &&
1235 	    (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) {
1236 		sign_key = id->key;
1237 	} else {
1238 		/* Load the private key from the file. */
1239 		if ((prv = load_identity_file(id)) == NULL)
1240 			return SSH_ERR_KEY_NOT_FOUND;
1241 		if (id->key != NULL && !sshkey_equal_public(prv, id->key)) {
1242 			error_f("private key %s contents do not match public",
1243 			   id->filename);
1244 			r = SSH_ERR_KEY_NOT_FOUND;
1245 			goto out;
1246 		}
1247 		sign_key = prv;
1248 		if (sshkey_is_sk(sign_key)) {
1249 			if ((sign_key->sk_flags &
1250 			    SSH_SK_USER_VERIFICATION_REQD)) {
1251 				xasprintf(&prompt, "Enter PIN for %s key %s: ",
1252 				    sshkey_type(sign_key), id->filename);
1253 				pin = read_passphrase(prompt, 0);
1254 			}
1255 			if ((sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) {
1256 				/* XXX should batch mode just skip these? */
1257 				if ((fp = sshkey_fingerprint(sign_key,
1258 				    options.fingerprint_hash,
1259 				    SSH_FP_DEFAULT)) == NULL)
1260 					fatal_f("fingerprint failed");
1261 				notifier = notify_start(options.batch_mode,
1262 				    "Confirm user presence for key %s %s",
1263 				    sshkey_type(sign_key), fp);
1264 				free(fp);
1265 			}
1266 		}
1267 	}
1268 	if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen,
1269 	    alg, options.sk_provider, pin, compat)) != 0) {
1270 		debug_fr(r, "sshkey_sign");
1271 		goto out;
1272 	}
1273 	/*
1274 	 * PKCS#11 tokens may not support all signature algorithms,
1275 	 * so check what we get back.
1276 	 */
1277 	if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) {
1278 		debug_fr(r, "sshkey_check_sigtype");
1279 		goto out;
1280 	}
1281 	/* success */
1282 	r = 0;
1283  out:
1284 	free(prompt);
1285 	if (pin != NULL)
1286 		freezero(pin, strlen(pin));
1287 	notify_complete(notifier, "User presence confirmed");
1288 	sshkey_free(prv);
1289 	return r;
1290 }
1291 
1292 static int
1293 id_filename_matches(Identity *id, Identity *private_id)
1294 {
1295 	const char *suffixes[] = { ".pub", "-cert.pub", NULL };
1296 	size_t len = strlen(id->filename), plen = strlen(private_id->filename);
1297 	size_t i, slen;
1298 
1299 	if (strcmp(id->filename, private_id->filename) == 0)
1300 		return 1;
1301 	for (i = 0; suffixes[i]; i++) {
1302 		slen = strlen(suffixes[i]);
1303 		if (len > slen && plen == len - slen &&
1304 		    strcmp(id->filename + (len - slen), suffixes[i]) == 0 &&
1305 		    memcmp(id->filename, private_id->filename, plen) == 0)
1306 			return 1;
1307 	}
1308 	return 0;
1309 }
1310 
1311 static int
1312 sign_and_send_pubkey(struct ssh *ssh, Identity *id)
1313 {
1314 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1315 	struct sshbuf *b = NULL;
1316 	Identity *private_id, *sign_id = NULL;
1317 	u_char *signature = NULL;
1318 	size_t slen = 0, skip = 0;
1319 	int r, fallback_sigtype, sent = 0;
1320 	char *alg = NULL, *fp = NULL;
1321 	const char *loc = "";
1322 
1323 	if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
1324 	    SSH_FP_DEFAULT)) == NULL)
1325 		return 0;
1326 
1327 	debug3_f("%s %s", sshkey_type(id->key), fp);
1328 
1329 	/*
1330 	 * If the key is an certificate, try to find a matching private key
1331 	 * and use it to complete the signature.
1332 	 * If no such private key exists, fall back to trying the certificate
1333 	 * key itself in case it has a private half already loaded.
1334 	 * This will try to set sign_id to the private key that will perform
1335 	 * the signature.
1336 	 */
1337 	if (sshkey_is_cert(id->key)) {
1338 		TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1339 			if (sshkey_equal_public(id->key, private_id->key) &&
1340 			    id->key->type != private_id->key->type) {
1341 				sign_id = private_id;
1342 				break;
1343 			}
1344 		}
1345 		/*
1346 		 * Exact key matches are preferred, but also allow
1347 		 * filename matches for non-PKCS#11/agent keys that
1348 		 * didn't load public keys. This supports the case
1349 		 * of keeping just a private key file and public
1350 		 * certificate on disk.
1351 		 */
1352 		if (sign_id == NULL &&
1353 		    !id->isprivate && id->agent_fd == -1 &&
1354 		    (id->key->flags & SSHKEY_FLAG_EXT) == 0) {
1355 			TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1356 				if (private_id->key == NULL &&
1357 				    id_filename_matches(id, private_id)) {
1358 					sign_id = private_id;
1359 					break;
1360 				}
1361 			}
1362 		}
1363 		if (sign_id != NULL) {
1364 			debug2_f("using private key \"%s\"%s for "
1365 			    "certificate", id->filename,
1366 			    id->agent_fd != -1 ? " from agent" : "");
1367 		} else {
1368 			debug_f("no separate private key for certificate "
1369 			    "\"%s\"", id->filename);
1370 		}
1371 	}
1372 
1373 	/*
1374 	 * If the above didn't select another identity to do the signing
1375 	 * then default to the one we started with.
1376 	 */
1377 	if (sign_id == NULL)
1378 		sign_id = id;
1379 
1380 	/* assemble and sign data */
1381 	for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) {
1382 		free(alg);
1383 		slen = 0;
1384 		signature = NULL;
1385 		if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh,
1386 		    id->key)) == NULL) {
1387 			error_f("no mutual signature supported");
1388 			goto out;
1389 		}
1390 		debug3_f("signing using %s %s", alg, fp);
1391 
1392 		sshbuf_free(b);
1393 		if ((b = sshbuf_new()) == NULL)
1394 			fatal_f("sshbuf_new failed");
1395 		if (datafellows & SSH_OLD_SESSIONID) {
1396 			if ((r = sshbuf_put(b, session_id2,
1397 			    session_id2_len)) != 0)
1398 				fatal_fr(r, "sshbuf_put");
1399 		} else {
1400 			if ((r = sshbuf_put_string(b, session_id2,
1401 			    session_id2_len)) != 0)
1402 				fatal_fr(r, "sshbuf_put_string");
1403 		}
1404 		skip = sshbuf_len(b);
1405 		if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1406 		    (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
1407 		    (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
1408 		    (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
1409 		    (r = sshbuf_put_u8(b, 1)) != 0 ||
1410 		    (r = sshbuf_put_cstring(b, alg)) != 0 ||
1411 		    (r = sshkey_puts(id->key, b)) != 0) {
1412 			fatal_fr(r, "assemble signed data");
1413 		}
1414 
1415 		/* generate signature */
1416 		r = identity_sign(sign_id, &signature, &slen,
1417 		    sshbuf_ptr(b), sshbuf_len(b), datafellows, alg);
1418 		if (r == 0)
1419 			break;
1420 		else if (r == SSH_ERR_KEY_NOT_FOUND)
1421 			goto out; /* soft failure */
1422 		else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED &&
1423 		    !fallback_sigtype) {
1424 			if (sign_id->agent_fd != -1)
1425 				loc = "agent ";
1426 			else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0)
1427 				loc = "token ";
1428 			logit("%skey %s %s returned incorrect signature type",
1429 			    loc, sshkey_type(id->key), fp);
1430 			continue;
1431 		}
1432 		error_fr(r, "signing failed for %s \"%s\"%s",
1433 		    sshkey_type(sign_id->key), sign_id->filename,
1434 		    id->agent_fd != -1 ? " from agent" : "");
1435 		goto out;
1436 	}
1437 	if (slen == 0 || signature == NULL) /* shouldn't happen */
1438 		fatal_f("no signature");
1439 
1440 	/* append signature */
1441 	if ((r = sshbuf_put_string(b, signature, slen)) != 0)
1442 		fatal_fr(r, "append signature");
1443 
1444 #ifdef DEBUG_PK
1445 	sshbuf_dump(b, stderr);
1446 #endif
1447 	/* skip session id and packet type */
1448 	if ((r = sshbuf_consume(b, skip + 1)) != 0)
1449 		fatal_fr(r, "consume");
1450 
1451 	/* put remaining data from buffer into packet */
1452 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1453 	    (r = sshpkt_putb(ssh, b)) != 0 ||
1454 	    (r = sshpkt_send(ssh)) != 0)
1455 		fatal_fr(r, "enqueue request");
1456 
1457 	/* success */
1458 	sent = 1;
1459 
1460  out:
1461 	free(fp);
1462 	free(alg);
1463 	sshbuf_free(b);
1464 	freezero(signature, slen);
1465 	return sent;
1466 }
1467 
1468 static int
1469 send_pubkey_test(struct ssh *ssh, Identity *id)
1470 {
1471 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1472 	u_char *blob = NULL;
1473 	char *alg = NULL;
1474 	size_t bloblen;
1475 	u_int have_sig = 0;
1476 	int sent = 0, r;
1477 
1478 	if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) {
1479 		debug_f("no mutual signature algorithm");
1480 		goto out;
1481 	}
1482 
1483 	if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) {
1484 		/* we cannot handle this key */
1485 		debug3_f("cannot handle key");
1486 		goto out;
1487 	}
1488 	/* register callback for USERAUTH_PK_OK message */
1489 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1490 
1491 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1492 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1493 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1494 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1495 	    (r = sshpkt_put_u8(ssh, have_sig)) != 0 ||
1496 	    (r = sshpkt_put_cstring(ssh, alg)) != 0 ||
1497 	    (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 ||
1498 	    (r = sshpkt_send(ssh)) != 0)
1499 		fatal_fr(r, "send packet");
1500 	sent = 1;
1501 
1502  out:
1503 	free(alg);
1504 	free(blob);
1505 	return sent;
1506 }
1507 
1508 static struct sshkey *
1509 load_identity_file(Identity *id)
1510 {
1511 	struct sshkey *private = NULL;
1512 	char prompt[300], *passphrase, *comment;
1513 	int r, quit = 0, i;
1514 	struct stat st;
1515 
1516 	if (stat(id->filename, &st) == -1) {
1517 		do_log2(id->userprovided ?
1518 		    SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3,
1519 		    "no such identity: %s: %s", id->filename, strerror(errno));
1520 		return NULL;
1521 	}
1522 	snprintf(prompt, sizeof prompt,
1523 	    "Enter passphrase for key '%.100s': ", id->filename);
1524 	for (i = 0; i <= options.number_of_password_prompts; i++) {
1525 		if (i == 0)
1526 			passphrase = "";
1527 		else {
1528 			passphrase = read_passphrase(prompt, 0);
1529 			if (*passphrase == '\0') {
1530 				debug2("no passphrase given, try next key");
1531 				free(passphrase);
1532 				break;
1533 			}
1534 		}
1535 		switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename,
1536 		    passphrase, &private, &comment))) {
1537 		case 0:
1538 			break;
1539 		case SSH_ERR_KEY_WRONG_PASSPHRASE:
1540 			if (options.batch_mode) {
1541 				quit = 1;
1542 				break;
1543 			}
1544 			if (i != 0)
1545 				debug2("bad passphrase given, try again...");
1546 			break;
1547 		case SSH_ERR_SYSTEM_ERROR:
1548 			if (errno == ENOENT) {
1549 				debug2_r(r, "Load key \"%s\"", id->filename);
1550 				quit = 1;
1551 				break;
1552 			}
1553 			/* FALLTHROUGH */
1554 		default:
1555 			error_r(r, "Load key \"%s\"", id->filename);
1556 			quit = 1;
1557 			break;
1558 		}
1559 		if (private != NULL && sshkey_is_sk(private) &&
1560 		    options.sk_provider == NULL) {
1561 			debug("key \"%s\" is an authenticator-hosted key, "
1562 			    "but no provider specified", id->filename);
1563 			sshkey_free(private);
1564 			private = NULL;
1565 			quit = 1;
1566 		}
1567 		if (!quit && private != NULL && id->agent_fd == -1 &&
1568 		    !(id->key && id->isprivate))
1569 			maybe_add_key_to_agent(id->filename, private, comment,
1570 			    passphrase);
1571 		if (i > 0)
1572 			freezero(passphrase, strlen(passphrase));
1573 		free(comment);
1574 		if (private != NULL || quit)
1575 			break;
1576 	}
1577 	return private;
1578 }
1579 
1580 static int
1581 key_type_allowed_by_config(struct sshkey *key)
1582 {
1583 	if (match_pattern_list(sshkey_ssh_name(key),
1584 	    options.pubkey_key_types, 0) == 1)
1585 		return 1;
1586 
1587 	/* RSA keys/certs might be allowed by alternate signature types */
1588 	switch (key->type) {
1589 	case KEY_RSA:
1590 		if (match_pattern_list("rsa-sha2-512",
1591 		    options.pubkey_key_types, 0) == 1)
1592 			return 1;
1593 		if (match_pattern_list("rsa-sha2-256",
1594 		    options.pubkey_key_types, 0) == 1)
1595 			return 1;
1596 		break;
1597 	case KEY_RSA_CERT:
1598 		if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com",
1599 		    options.pubkey_key_types, 0) == 1)
1600 			return 1;
1601 		if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com",
1602 		    options.pubkey_key_types, 0) == 1)
1603 			return 1;
1604 		break;
1605 	}
1606 	return 0;
1607 }
1608 
1609 
1610 /*
1611  * try keys in the following order:
1612  *	1. certificates listed in the config file
1613  *	2. other input certificates
1614  *	3. agent keys that are found in the config file
1615  *	4. other agent keys
1616  *	5. keys that are only listed in the config file
1617  */
1618 static void
1619 pubkey_prepare(Authctxt *authctxt)
1620 {
1621 	struct identity *id, *id2, *tmp;
1622 	struct idlist agent, files, *preferred;
1623 	struct sshkey *key;
1624 	int agent_fd = -1, i, r, found;
1625 	size_t j;
1626 	struct ssh_identitylist *idlist;
1627 	char *ident;
1628 
1629 	TAILQ_INIT(&agent);	/* keys from the agent */
1630 	TAILQ_INIT(&files);	/* keys from the config file */
1631 	preferred = &authctxt->keys;
1632 	TAILQ_INIT(preferred);	/* preferred order of keys */
1633 
1634 	/* list of keys stored in the filesystem and PKCS#11 */
1635 	for (i = 0; i < options.num_identity_files; i++) {
1636 		key = options.identity_keys[i];
1637 		if (key && key->cert &&
1638 		    key->cert->type != SSH2_CERT_TYPE_USER) {
1639 			debug_f("ignoring certificate %s: not a user "
1640 			    "certificate", options.identity_files[i]);
1641 			continue;
1642 		}
1643 		if (key && sshkey_is_sk(key) && options.sk_provider == NULL) {
1644 			debug_f("ignoring authenticator-hosted key %s as no "
1645 			    "SecurityKeyProvider has been specified",
1646 			    options.identity_files[i]);
1647 			continue;
1648 		}
1649 		options.identity_keys[i] = NULL;
1650 		id = xcalloc(1, sizeof(*id));
1651 		id->agent_fd = -1;
1652 		id->key = key;
1653 		id->filename = xstrdup(options.identity_files[i]);
1654 		id->userprovided = options.identity_file_userprovided[i];
1655 		TAILQ_INSERT_TAIL(&files, id, next);
1656 	}
1657 	/* list of certificates specified by user */
1658 	for (i = 0; i < options.num_certificate_files; i++) {
1659 		key = options.certificates[i];
1660 		if (!sshkey_is_cert(key) || key->cert == NULL ||
1661 		    key->cert->type != SSH2_CERT_TYPE_USER) {
1662 			debug_f("ignoring certificate %s: not a user "
1663 			    "certificate", options.identity_files[i]);
1664 			continue;
1665 		}
1666 		if (key && sshkey_is_sk(key) && options.sk_provider == NULL) {
1667 			debug_f("ignoring authenticator-hosted key "
1668 			    "certificate %s as no "
1669 			    "SecurityKeyProvider has been specified",
1670 			    options.identity_files[i]);
1671 			continue;
1672 		}
1673 		id = xcalloc(1, sizeof(*id));
1674 		id->agent_fd = -1;
1675 		id->key = key;
1676 		id->filename = xstrdup(options.certificate_files[i]);
1677 		id->userprovided = options.certificate_file_userprovided[i];
1678 		TAILQ_INSERT_TAIL(preferred, id, next);
1679 	}
1680 	/* list of keys supported by the agent */
1681 	if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) {
1682 		if (r != SSH_ERR_AGENT_NOT_PRESENT)
1683 			debug_fr(r, "ssh_get_authentication_socket");
1684 	} else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) {
1685 		if (r != SSH_ERR_AGENT_NO_IDENTITIES)
1686 			debug_fr(r, "ssh_fetch_identitylist");
1687 		close(agent_fd);
1688 	} else {
1689 		for (j = 0; j < idlist->nkeys; j++) {
1690 			found = 0;
1691 			TAILQ_FOREACH(id, &files, next) {
1692 				/*
1693 				 * agent keys from the config file are
1694 				 * preferred
1695 				 */
1696 				if (sshkey_equal(idlist->keys[j], id->key)) {
1697 					TAILQ_REMOVE(&files, id, next);
1698 					TAILQ_INSERT_TAIL(preferred, id, next);
1699 					id->agent_fd = agent_fd;
1700 					found = 1;
1701 					break;
1702 				}
1703 			}
1704 			if (!found && !options.identities_only) {
1705 				id = xcalloc(1, sizeof(*id));
1706 				/* XXX "steals" key/comment from idlist */
1707 				id->key = idlist->keys[j];
1708 				id->filename = idlist->comments[j];
1709 				idlist->keys[j] = NULL;
1710 				idlist->comments[j] = NULL;
1711 				id->agent_fd = agent_fd;
1712 				TAILQ_INSERT_TAIL(&agent, id, next);
1713 			}
1714 		}
1715 		ssh_free_identitylist(idlist);
1716 		/* append remaining agent keys */
1717 		TAILQ_CONCAT(preferred, &agent, next);
1718 		authctxt->agent_fd = agent_fd;
1719 	}
1720 	/* Prefer PKCS11 keys that are explicitly listed */
1721 	TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1722 		if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0)
1723 			continue;
1724 		found = 0;
1725 		TAILQ_FOREACH(id2, &files, next) {
1726 			if (id2->key == NULL ||
1727 			    (id2->key->flags & SSHKEY_FLAG_EXT) != 0)
1728 				continue;
1729 			if (sshkey_equal(id->key, id2->key)) {
1730 				TAILQ_REMOVE(&files, id, next);
1731 				TAILQ_INSERT_TAIL(preferred, id, next);
1732 				found = 1;
1733 				break;
1734 			}
1735 		}
1736 		/* If IdentitiesOnly set and key not found then don't use it */
1737 		if (!found && options.identities_only) {
1738 			TAILQ_REMOVE(&files, id, next);
1739 			freezero(id, sizeof(*id));
1740 		}
1741 	}
1742 	/* append remaining keys from the config file */
1743 	TAILQ_CONCAT(preferred, &files, next);
1744 	/* finally, filter by PubkeyAcceptedKeyTypes */
1745 	TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
1746 		if (id->key != NULL && !key_type_allowed_by_config(id->key)) {
1747 			debug("Skipping %s key %s - "
1748 			    "not in PubkeyAcceptedKeyTypes",
1749 			    sshkey_ssh_name(id->key), id->filename);
1750 			TAILQ_REMOVE(preferred, id, next);
1751 			sshkey_free(id->key);
1752 			free(id->filename);
1753 			memset(id, 0, sizeof(*id));
1754 			continue;
1755 		}
1756 	}
1757 	/* List the keys we plan on using */
1758 	TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
1759 		ident = format_identity(id);
1760 		debug("Will attempt key: %s", ident);
1761 		free(ident);
1762 	}
1763 	debug2_f("done");
1764 }
1765 
1766 static void
1767 pubkey_cleanup(struct ssh *ssh)
1768 {
1769 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1770 	Identity *id;
1771 
1772 	if (authctxt->agent_fd != -1) {
1773 		ssh_close_authentication_socket(authctxt->agent_fd);
1774 		authctxt->agent_fd = -1;
1775 	}
1776 	for (id = TAILQ_FIRST(&authctxt->keys); id;
1777 	    id = TAILQ_FIRST(&authctxt->keys)) {
1778 		TAILQ_REMOVE(&authctxt->keys, id, next);
1779 		sshkey_free(id->key);
1780 		free(id->filename);
1781 		free(id);
1782 	}
1783 }
1784 
1785 static void
1786 pubkey_reset(Authctxt *authctxt)
1787 {
1788 	Identity *id;
1789 
1790 	TAILQ_FOREACH(id, &authctxt->keys, next)
1791 		id->tried = 0;
1792 }
1793 
1794 static int
1795 try_identity(Identity *id)
1796 {
1797 	if (!id->key)
1798 		return (0);
1799 	if (sshkey_type_plain(id->key->type) == KEY_RSA &&
1800 	    (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1801 		debug("Skipped %s key %s for RSA/MD5 server",
1802 		    sshkey_type(id->key), id->filename);
1803 		return (0);
1804 	}
1805 	return 1;
1806 }
1807 
1808 static int
1809 userauth_pubkey(struct ssh *ssh)
1810 {
1811 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1812 	Identity *id;
1813 	int sent = 0;
1814 	char *ident;
1815 
1816 	while ((id = TAILQ_FIRST(&authctxt->keys))) {
1817 		if (id->tried++)
1818 			return (0);
1819 		/* move key to the end of the queue */
1820 		TAILQ_REMOVE(&authctxt->keys, id, next);
1821 		TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1822 		/*
1823 		 * send a test message if we have the public key. for
1824 		 * encrypted keys we cannot do this and have to load the
1825 		 * private key instead
1826 		 */
1827 		if (id->key != NULL) {
1828 			if (try_identity(id)) {
1829 				ident = format_identity(id);
1830 				debug("Offering public key: %s", ident);
1831 				free(ident);
1832 				sent = send_pubkey_test(ssh, id);
1833 			}
1834 		} else {
1835 			debug("Trying private key: %s", id->filename);
1836 			id->key = load_identity_file(id);
1837 			if (id->key != NULL) {
1838 				if (try_identity(id)) {
1839 					id->isprivate = 1;
1840 					sent = sign_and_send_pubkey(ssh, id);
1841 				}
1842 				sshkey_free(id->key);
1843 				id->key = NULL;
1844 				id->isprivate = 0;
1845 			}
1846 		}
1847 		if (sent)
1848 			return (sent);
1849 	}
1850 	return (0);
1851 }
1852 
1853 /*
1854  * Send userauth request message specifying keyboard-interactive method.
1855  */
1856 static int
1857 userauth_kbdint(struct ssh *ssh)
1858 {
1859 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1860 	int r;
1861 
1862 	if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts)
1863 		return 0;
1864 	/* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1865 	if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) {
1866 		debug3("userauth_kbdint: disable: no info_req_seen");
1867 		ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1868 		return 0;
1869 	}
1870 
1871 	debug2("userauth_kbdint");
1872 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1873 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1874 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1875 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1876 	    (r = sshpkt_put_cstring(ssh, "")) != 0 ||		/* lang */
1877 	    (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ?
1878 	    options.kbd_interactive_devices : "")) != 0 ||
1879 	    (r = sshpkt_send(ssh)) != 0)
1880 		fatal_fr(r, "send packet");
1881 
1882 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1883 	return 1;
1884 }
1885 
1886 /*
1887  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1888  */
1889 static int
1890 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh)
1891 {
1892 	Authctxt *authctxt = ssh->authctxt;
1893 	char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL;
1894 	char *display_prompt = NULL, *response = NULL;
1895 	u_char echo = 0;
1896 	u_int num_prompts, i;
1897 	int r;
1898 
1899 	debug2_f("entering");
1900 
1901 	if (authctxt == NULL)
1902 		fatal_f("no authentication context");
1903 
1904 	authctxt->info_req_seen = 1;
1905 
1906 	if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 ||
1907 	    (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 ||
1908 	    (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
1909 		goto out;
1910 	if (strlen(name) > 0)
1911 		logit("%s", name);
1912 	if (strlen(inst) > 0)
1913 		logit("%s", inst);
1914 
1915 	if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0)
1916 		goto out;
1917 	/*
1918 	 * Begin to build info response packet based on prompts requested.
1919 	 * We commit to providing the correct number of responses, so if
1920 	 * further on we run into a problem that prevents this, we have to
1921 	 * be sure and clean this up and send a correct error response.
1922 	 */
1923 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 ||
1924 	    (r = sshpkt_put_u32(ssh, num_prompts)) != 0)
1925 		goto out;
1926 
1927 	debug2_f("num_prompts %d", num_prompts);
1928 	for (i = 0; i < num_prompts; i++) {
1929 		if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 ||
1930 		    (r = sshpkt_get_u8(ssh, &echo)) != 0)
1931 			goto out;
1932 		if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s",
1933 		    authctxt->server_user, options.host_key_alias ?
1934 		    options.host_key_alias : authctxt->host, prompt) == -1)
1935 			fatal_f("asmprintf failed");
1936 		response = read_passphrase(display_prompt, echo ? RP_ECHO : 0);
1937 		if ((r = sshpkt_put_cstring(ssh, response)) != 0)
1938 			goto out;
1939 		freezero(response, strlen(response));
1940 		free(prompt);
1941 		free(display_prompt);
1942 		display_prompt = response = prompt = NULL;
1943 	}
1944 	/* done with parsing incoming message. */
1945 	if ((r = sshpkt_get_end(ssh)) != 0 ||
1946 	    (r = sshpkt_add_padding(ssh, 64)) != 0)
1947 		goto out;
1948 	r = sshpkt_send(ssh);
1949  out:
1950 	if (response)
1951 		freezero(response, strlen(response));
1952 	free(prompt);
1953 	free(display_prompt);
1954 	free(name);
1955 	free(inst);
1956 	free(lang);
1957 	return r;
1958 }
1959 
1960 static int
1961 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
1962     const u_char *data, size_t datalen)
1963 {
1964 	struct sshbuf *b;
1965 	struct stat st;
1966 	pid_t pid;
1967 	int r, to[2], from[2], status;
1968 	int sock = ssh_packet_get_connection_in(ssh);
1969 	u_char rversion = 0, version = 2;
1970 	void (*osigchld)(int);
1971 
1972 	*sigp = NULL;
1973 	*lenp = 0;
1974 
1975 	if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) {
1976 		error_f("not installed: %s", strerror(errno));
1977 		return -1;
1978 	}
1979 	if (fflush(stdout) != 0) {
1980 		error_f("fflush: %s", strerror(errno));
1981 		return -1;
1982 	}
1983 	if (pipe(to) == -1) {
1984 		error_f("pipe: %s", strerror(errno));
1985 		return -1;
1986 	}
1987 	if (pipe(from) == -1) {
1988 		error_f("pipe: %s", strerror(errno));
1989 		return -1;
1990 	}
1991 	if ((pid = fork()) == -1) {
1992 		error_f("fork: %s", strerror(errno));
1993 		return -1;
1994 	}
1995 	osigchld = ssh_signal(SIGCHLD, SIG_DFL);
1996 	if (pid == 0) {
1997 		close(from[0]);
1998 		if (dup2(from[1], STDOUT_FILENO) == -1)
1999 			fatal_f("dup2: %s", strerror(errno));
2000 		close(to[1]);
2001 		if (dup2(to[0], STDIN_FILENO) == -1)
2002 			fatal_f("dup2: %s", strerror(errno));
2003 		close(from[1]);
2004 		close(to[0]);
2005 
2006 		if (dup2(sock, STDERR_FILENO + 1) == -1)
2007 			fatal_f("dup2: %s", strerror(errno));
2008 		sock = STDERR_FILENO + 1;
2009 		fcntl(sock, F_SETFD, 0);	/* keep the socket on exec */
2010 		closefrom(sock + 1);
2011 
2012 		debug3_f("[child] pid=%ld, exec %s",
2013 		    (long)getpid(), _PATH_SSH_KEY_SIGN);
2014 		execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL);
2015 		fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN,
2016 		    strerror(errno));
2017 	}
2018 	close(from[1]);
2019 	close(to[0]);
2020 	sock = STDERR_FILENO + 1;
2021 
2022 	if ((b = sshbuf_new()) == NULL)
2023 		fatal_f("sshbuf_new failed");
2024 	/* send # of sock, data to be signed */
2025 	if ((r = sshbuf_put_u32(b, sock)) != 0 ||
2026 	    (r = sshbuf_put_string(b, data, datalen)) != 0)
2027 		fatal_fr(r, "buffer error");
2028 	if (ssh_msg_send(to[1], version, b) == -1)
2029 		fatal_f("couldn't send request");
2030 	sshbuf_reset(b);
2031 	r = ssh_msg_recv(from[0], b);
2032 	close(from[0]);
2033 	close(to[1]);
2034 	if (r < 0) {
2035 		error_f("no reply");
2036 		goto fail;
2037 	}
2038 
2039 	errno = 0;
2040 	while (waitpid(pid, &status, 0) == -1) {
2041 		if (errno != EINTR) {
2042 			error_f("waitpid %ld: %s", (long)pid, strerror(errno));
2043 			goto fail;
2044 		}
2045 	}
2046 	if (!WIFEXITED(status)) {
2047 		error_f("exited abnormally");
2048 		goto fail;
2049 	}
2050 	if (WEXITSTATUS(status) != 0) {
2051 		error_f("exited with status %d", WEXITSTATUS(status));
2052 		goto fail;
2053 	}
2054 	if ((r = sshbuf_get_u8(b, &rversion)) != 0) {
2055 		error_fr(r, "buffer error");
2056 		goto fail;
2057 	}
2058 	if (rversion != version) {
2059 		error_f("bad version");
2060 		goto fail;
2061 	}
2062 	if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) {
2063 		error_fr(r, "buffer error");
2064  fail:
2065 		ssh_signal(SIGCHLD, osigchld);
2066 		sshbuf_free(b);
2067 		return -1;
2068 	}
2069 	ssh_signal(SIGCHLD, osigchld);
2070 	sshbuf_free(b);
2071 
2072 	return 0;
2073 }
2074 
2075 static int
2076 userauth_hostbased(struct ssh *ssh)
2077 {
2078 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
2079 	struct sshkey *private = NULL;
2080 	struct sshbuf *b = NULL;
2081 	u_char *sig = NULL, *keyblob = NULL;
2082 	char *fp = NULL, *chost = NULL, *lname = NULL;
2083 	size_t siglen = 0, keylen = 0;
2084 	int i, r, success = 0;
2085 
2086 	if (authctxt->ktypes == NULL) {
2087 		authctxt->oktypes = xstrdup(options.hostbased_key_types);
2088 		authctxt->ktypes = authctxt->oktypes;
2089 	}
2090 
2091 	/*
2092 	 * Work through each listed type pattern in HostbasedKeyTypes,
2093 	 * trying each hostkey that matches the type in turn.
2094 	 */
2095 	for (;;) {
2096 		if (authctxt->active_ktype == NULL)
2097 			authctxt->active_ktype = strsep(&authctxt->ktypes, ",");
2098 		if (authctxt->active_ktype == NULL ||
2099 		    *authctxt->active_ktype == '\0')
2100 			break;
2101 		debug3_f("trying key type %s", authctxt->active_ktype);
2102 
2103 		/* check for a useful key */
2104 		private = NULL;
2105 		for (i = 0; i < authctxt->sensitive->nkeys; i++) {
2106 			if (authctxt->sensitive->keys[i] == NULL ||
2107 			    authctxt->sensitive->keys[i]->type == KEY_UNSPEC)
2108 				continue;
2109 			if (match_pattern_list(
2110 			    sshkey_ssh_name(authctxt->sensitive->keys[i]),
2111 			    authctxt->active_ktype, 0) != 1)
2112 				continue;
2113 			/* we take and free the key */
2114 			private = authctxt->sensitive->keys[i];
2115 			authctxt->sensitive->keys[i] = NULL;
2116 			break;
2117 		}
2118 		/* Found one */
2119 		if (private != NULL)
2120 			break;
2121 		/* No more keys of this type; advance */
2122 		authctxt->active_ktype = NULL;
2123 	}
2124 	if (private == NULL) {
2125 		free(authctxt->oktypes);
2126 		authctxt->oktypes = authctxt->ktypes = NULL;
2127 		authctxt->active_ktype = NULL;
2128 		debug("No more client hostkeys for hostbased authentication.");
2129 		goto out;
2130 	}
2131 
2132 	if ((fp = sshkey_fingerprint(private, options.fingerprint_hash,
2133 	    SSH_FP_DEFAULT)) == NULL) {
2134 		error_f("sshkey_fingerprint failed");
2135 		goto out;
2136 	}
2137 	debug_f("trying hostkey %s %s", sshkey_ssh_name(private), fp);
2138 
2139 	/* figure out a name for the client host */
2140 	lname = get_local_name(ssh_packet_get_connection_in(ssh));
2141 	if (lname == NULL) {
2142 		error_f("cannot get local ipaddr/name");
2143 		goto out;
2144 	}
2145 
2146 	/* XXX sshbuf_put_stringf? */
2147 	xasprintf(&chost, "%s.", lname);
2148 	debug2_f("chost %s", chost);
2149 
2150 	/* construct data */
2151 	if ((b = sshbuf_new()) == NULL) {
2152 		error_f("sshbuf_new failed");
2153 		goto out;
2154 	}
2155 	if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) {
2156 		error_fr(r, "sshkey_to_blob");
2157 		goto out;
2158 	}
2159 	if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 ||
2160 	    (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
2161 	    (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
2162 	    (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
2163 	    (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
2164 	    (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 ||
2165 	    (r = sshbuf_put_string(b, keyblob, keylen)) != 0 ||
2166 	    (r = sshbuf_put_cstring(b, chost)) != 0 ||
2167 	    (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) {
2168 		error_fr(r, "buffer error");
2169 		goto out;
2170 	}
2171 
2172 #ifdef DEBUG_PK
2173 	sshbuf_dump(b, stderr);
2174 #endif
2175 	if ((r = ssh_keysign(ssh, private, &sig, &siglen,
2176 	    sshbuf_ptr(b), sshbuf_len(b))) != 0) {
2177 		error("sign using hostkey %s %s failed",
2178 		    sshkey_ssh_name(private), fp);
2179 		goto out;
2180 	}
2181 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
2182 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
2183 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
2184 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
2185 	    (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 ||
2186 	    (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 ||
2187 	    (r = sshpkt_put_cstring(ssh, chost)) != 0 ||
2188 	    (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 ||
2189 	    (r = sshpkt_put_string(ssh, sig, siglen)) != 0 ||
2190 	    (r = sshpkt_send(ssh)) != 0) {
2191 		error_fr(r, "packet error");
2192 		goto out;
2193 	}
2194 	success = 1;
2195 
2196  out:
2197 	if (sig != NULL)
2198 		freezero(sig, siglen);
2199 	free(keyblob);
2200 	free(lname);
2201 	free(fp);
2202 	free(chost);
2203 	sshkey_free(private);
2204 	sshbuf_free(b);
2205 
2206 	return success;
2207 }
2208 
2209 /* find auth method */
2210 
2211 /*
2212  * given auth method name, if configurable options permit this method fill
2213  * in auth_ident field and return true, otherwise return false.
2214  */
2215 static int
2216 authmethod_is_enabled(Authmethod *method)
2217 {
2218 	if (method == NULL)
2219 		return 0;
2220 	/* return false if options indicate this method is disabled */
2221 	if  (method->enabled == NULL || *method->enabled == 0)
2222 		return 0;
2223 	/* return false if batch mode is enabled but method needs interactive mode */
2224 	if  (method->batch_flag != NULL && *method->batch_flag != 0)
2225 		return 0;
2226 	return 1;
2227 }
2228 
2229 static Authmethod *
2230 authmethod_lookup(const char *name)
2231 {
2232 	Authmethod *method = NULL;
2233 	if (name != NULL)
2234 		for (method = authmethods; method->name != NULL; method++)
2235 			if (strcmp(name, method->name) == 0)
2236 				return method;
2237 	debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
2238 	return NULL;
2239 }
2240 
2241 /* XXX internal state */
2242 static Authmethod *current = NULL;
2243 static char *supported = NULL;
2244 static char *preferred = NULL;
2245 
2246 /*
2247  * Given the authentication method list sent by the server, return the
2248  * next method we should try.  If the server initially sends a nil list,
2249  * use a built-in default list.
2250  */
2251 static Authmethod *
2252 authmethod_get(char *authlist)
2253 {
2254 	char *name = NULL;
2255 	u_int next;
2256 
2257 	/* Use a suitable default if we're passed a nil list.  */
2258 	if (authlist == NULL || strlen(authlist) == 0)
2259 		authlist = options.preferred_authentications;
2260 
2261 	if (supported == NULL || strcmp(authlist, supported) != 0) {
2262 		debug3("start over, passed a different list %s", authlist);
2263 		free(supported);
2264 		supported = xstrdup(authlist);
2265 		preferred = options.preferred_authentications;
2266 		debug3("preferred %s", preferred);
2267 		current = NULL;
2268 	} else if (current != NULL && authmethod_is_enabled(current))
2269 		return current;
2270 
2271 	for (;;) {
2272 		if ((name = match_list(preferred, supported, &next)) == NULL) {
2273 			debug("No more authentication methods to try.");
2274 			current = NULL;
2275 			return NULL;
2276 		}
2277 		preferred += next;
2278 		debug3("authmethod_lookup %s", name);
2279 		debug3("remaining preferred: %s", preferred);
2280 		if ((current = authmethod_lookup(name)) != NULL &&
2281 		    authmethod_is_enabled(current)) {
2282 			debug3("authmethod_is_enabled %s", name);
2283 			debug("Next authentication method: %s", name);
2284 			free(name);
2285 			return current;
2286 		}
2287 		free(name);
2288 	}
2289 }
2290 
2291 static char *
2292 authmethods_get(void)
2293 {
2294 	Authmethod *method = NULL;
2295 	struct sshbuf *b;
2296 	char *list;
2297 	int r;
2298 
2299 	if ((b = sshbuf_new()) == NULL)
2300 		fatal_f("sshbuf_new failed");
2301 	for (method = authmethods; method->name != NULL; method++) {
2302 		if (authmethod_is_enabled(method)) {
2303 			if ((r = sshbuf_putf(b, "%s%s",
2304 			    sshbuf_len(b) ? "," : "", method->name)) != 0)
2305 				fatal_fr(r, "buffer error");
2306 		}
2307 	}
2308 	if ((list = sshbuf_dup_string(b)) == NULL)
2309 		fatal_f("sshbuf_dup_string failed");
2310 	sshbuf_free(b);
2311 	return list;
2312 }
2313