xref: /openssh-portable/sshconnect2.c (revision 96bd895a)
1 /* $OpenBSD: sshconnect2.c,v 1.320 2020/02/06 22:48:23 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
verify_host_key_callback(struct sshkey * hostkey,struct ssh * ssh)98 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh)
99 {
100 	if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
101 		fatal("Host key verification failed.");
102 	return 0;
103 }
104 
105 static char *
order_hostkeyalgs(char * host,struct sockaddr * hostaddr,u_short port)106 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
107 {
108 	char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
109 	size_t maxlen;
110 	struct hostkeys *hostkeys;
111 	int ktype;
112 	u_int i;
113 
114 	/* Find all hostkeys for this hostname */
115 	get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
116 	hostkeys = init_hostkeys();
117 	for (i = 0; i < options.num_user_hostfiles; i++)
118 		load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
119 	for (i = 0; i < options.num_system_hostfiles; i++)
120 		load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
121 
122 	oavail = avail = xstrdup(options.hostkeyalgorithms);
123 	maxlen = strlen(avail) + 1;
124 	first = xmalloc(maxlen);
125 	last = xmalloc(maxlen);
126 	*first = *last = '\0';
127 
128 #define ALG_APPEND(to, from) \
129 	do { \
130 		if (*to != '\0') \
131 			strlcat(to, ",", maxlen); \
132 		strlcat(to, from, maxlen); \
133 	} while (0)
134 
135 	while ((alg = strsep(&avail, ",")) && *alg != '\0') {
136 		if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
137 			fatal("%s: unknown alg %s", __func__, alg);
138 		if (lookup_key_in_hostkeys_by_type(hostkeys,
139 		    sshkey_type_plain(ktype), NULL))
140 			ALG_APPEND(first, alg);
141 		else
142 			ALG_APPEND(last, alg);
143 	}
144 #undef ALG_APPEND
145 	xasprintf(&ret, "%s%s%s", first,
146 	    (*first == '\0' || *last == '\0') ? "" : ",", last);
147 	if (*first != '\0')
148 		debug3("%s: prefer hostkeyalgs: %s", __func__, first);
149 
150 	free(first);
151 	free(last);
152 	free(hostname);
153 	free(oavail);
154 	free_hostkeys(hostkeys);
155 
156 	return ret;
157 }
158 
159 void
ssh_kex2(struct ssh * ssh,char * host,struct sockaddr * hostaddr,u_short port)160 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port)
161 {
162 	char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
163 	char *s, *all_key;
164 	int r, use_known_hosts_order = 0;
165 
166 	xxx_host = host;
167 	xxx_hostaddr = hostaddr;
168 
169 	/*
170 	 * If the user has not specified HostkeyAlgorithms, or has only
171 	 * appended or removed algorithms from that list then prefer algorithms
172 	 * that are in the list that are supported by known_hosts keys.
173 	 */
174 	if (options.hostkeyalgorithms == NULL ||
175 	    options.hostkeyalgorithms[0] == '-' ||
176 	    options.hostkeyalgorithms[0] == '+')
177 		use_known_hosts_order = 1;
178 
179 	/* Expand or fill in HostkeyAlgorithms */
180 	all_key = sshkey_alg_list(0, 0, 1, ',');
181 	if (kex_assemble_names(&options.hostkeyalgorithms,
182 	    kex_default_pk_alg(), all_key) != 0)
183 		fatal("%s: kex_assemble_namelist", __func__);
184 	free(all_key);
185 
186 	if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL)
187 		fatal("%s: kex_names_cat", __func__);
188 	myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s);
189 	myproposal[PROPOSAL_ENC_ALGS_CTOS] =
190 	    compat_cipher_proposal(options.ciphers);
191 	myproposal[PROPOSAL_ENC_ALGS_STOC] =
192 	    compat_cipher_proposal(options.ciphers);
193 	myproposal[PROPOSAL_COMP_ALGS_CTOS] =
194 	    myproposal[PROPOSAL_COMP_ALGS_STOC] =
195 	    (char *)compression_alg_list(options.compression);
196 	myproposal[PROPOSAL_MAC_ALGS_CTOS] =
197 	    myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
198 	if (use_known_hosts_order) {
199 		/* Query known_hosts and prefer algorithms that appear there */
200 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
201 		    compat_pkalg_proposal(
202 		    order_hostkeyalgs(host, hostaddr, port));
203 	} else {
204 		/* Use specified HostkeyAlgorithms exactly */
205 		myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
206 		    compat_pkalg_proposal(options.hostkeyalgorithms);
207 	}
208 
209 	if (options.rekey_limit || options.rekey_interval)
210 		ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
211 		    options.rekey_interval);
212 
213 	/* start key exchange */
214 	if ((r = kex_setup(ssh, myproposal)) != 0)
215 		fatal("kex_setup: %s", ssh_err(r));
216 #ifdef WITH_OPENSSL
217 	ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client;
218 	ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client;
219 	ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client;
220 	ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client;
221 	ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client;
222 	ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
223 	ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
224 # ifdef OPENSSL_HAS_ECC
225 	ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client;
226 # endif
227 #endif
228 	ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client;
229 	ssh->kex->kex[KEX_KEM_SNTRUP4591761X25519_SHA512] = kex_gen_client;
230 	ssh->kex->verify_host_key=&verify_host_key_callback;
231 
232 	ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done);
233 
234 	/* remove ext-info from the KEX proposals for rekeying */
235 	myproposal[PROPOSAL_KEX_ALGS] =
236 	    compat_kex_proposal(options.kex_algorithms);
237 	if ((r = kex_prop2buf(ssh->kex->my, myproposal)) != 0)
238 		fatal("kex_prop2buf: %s", ssh_err(r));
239 
240 	session_id2 = ssh->kex->session_id;
241 	session_id2_len = ssh->kex->session_id_len;
242 
243 #ifdef DEBUG_KEXDH
244 	/* send 1st encrypted/maced/compressed message */
245 	if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
246 	    (r = sshpkt_put_cstring(ssh, "markus")) != 0 ||
247 	    (r = sshpkt_send(ssh)) != 0 ||
248 	    (r = ssh_packet_write_wait(ssh)) != 0)
249 		fatal("%s: %s", __func__, ssh_err(r));
250 #endif
251 }
252 
253 /*
254  * Authenticate user
255  */
256 
257 typedef struct cauthctxt Authctxt;
258 typedef struct cauthmethod Authmethod;
259 typedef struct identity Identity;
260 typedef struct idlist Idlist;
261 
262 struct identity {
263 	TAILQ_ENTRY(identity) next;
264 	int	agent_fd;		/* >=0 if agent supports key */
265 	struct sshkey	*key;		/* public/private key */
266 	char	*filename;		/* comment for agent-only keys */
267 	int	tried;
268 	int	isprivate;		/* key points to the private key */
269 	int	userprovided;
270 };
271 TAILQ_HEAD(idlist, identity);
272 
273 struct cauthctxt {
274 	const char *server_user;
275 	const char *local_user;
276 	const char *host;
277 	const char *service;
278 	struct cauthmethod *method;
279 	sig_atomic_t success;
280 	char *authlist;
281 #ifdef GSSAPI
282 	/* gssapi */
283 	gss_OID_set gss_supported_mechs;
284 	u_int mech_tried;
285 #endif
286 	/* pubkey */
287 	struct idlist keys;
288 	int agent_fd;
289 	/* hostbased */
290 	Sensitive *sensitive;
291 	char *oktypes, *ktypes;
292 	const char *active_ktype;
293 	/* kbd-interactive */
294 	int info_req_seen;
295 	int attempt_kbdint;
296 	/* password */
297 	int attempt_passwd;
298 	/* generic */
299 	void *methoddata;
300 };
301 
302 struct cauthmethod {
303 	char	*name;		/* string to compare against server's list */
304 	int	(*userauth)(struct ssh *ssh);
305 	void	(*cleanup)(struct ssh *ssh);
306 	int	*enabled;	/* flag in option struct that enables method */
307 	int	*batch_flag;	/* flag in option struct that disables method */
308 };
309 
310 static int input_userauth_service_accept(int, u_int32_t, struct ssh *);
311 static int input_userauth_ext_info(int, u_int32_t, struct ssh *);
312 static int input_userauth_success(int, u_int32_t, struct ssh *);
313 static int input_userauth_failure(int, u_int32_t, struct ssh *);
314 static int input_userauth_banner(int, u_int32_t, struct ssh *);
315 static int input_userauth_error(int, u_int32_t, struct ssh *);
316 static int input_userauth_info_req(int, u_int32_t, struct ssh *);
317 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *);
318 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *);
319 
320 static int userauth_none(struct ssh *);
321 static int userauth_pubkey(struct ssh *);
322 static int userauth_passwd(struct ssh *);
323 static int userauth_kbdint(struct ssh *);
324 static int userauth_hostbased(struct ssh *);
325 
326 #ifdef GSSAPI
327 static int userauth_gssapi(struct ssh *);
328 static void userauth_gssapi_cleanup(struct ssh *);
329 static int input_gssapi_response(int type, u_int32_t, struct ssh *);
330 static int input_gssapi_token(int type, u_int32_t, struct ssh *);
331 static int input_gssapi_error(int, u_int32_t, struct ssh *);
332 static int input_gssapi_errtok(int, u_int32_t, struct ssh *);
333 #endif
334 
335 void	userauth(struct ssh *, char *);
336 
337 static void pubkey_cleanup(struct ssh *);
338 static int sign_and_send_pubkey(struct ssh *ssh, Identity *);
339 static void pubkey_prepare(Authctxt *);
340 static void pubkey_reset(Authctxt *);
341 static struct sshkey *load_identity_file(Identity *);
342 
343 static Authmethod *authmethod_get(char *authlist);
344 static Authmethod *authmethod_lookup(const char *name);
345 static char *authmethods_get(void);
346 
347 Authmethod authmethods[] = {
348 #ifdef GSSAPI
349 	{"gssapi-with-mic",
350 		userauth_gssapi,
351 		userauth_gssapi_cleanup,
352 		&options.gss_authentication,
353 		NULL},
354 #endif
355 	{"hostbased",
356 		userauth_hostbased,
357 		NULL,
358 		&options.hostbased_authentication,
359 		NULL},
360 	{"publickey",
361 		userauth_pubkey,
362 		NULL,
363 		&options.pubkey_authentication,
364 		NULL},
365 	{"keyboard-interactive",
366 		userauth_kbdint,
367 		NULL,
368 		&options.kbd_interactive_authentication,
369 		&options.batch_mode},
370 	{"password",
371 		userauth_passwd,
372 		NULL,
373 		&options.password_authentication,
374 		&options.batch_mode},
375 	{"none",
376 		userauth_none,
377 		NULL,
378 		NULL,
379 		NULL},
380 	{NULL, NULL, NULL, NULL, NULL}
381 };
382 
383 void
ssh_userauth2(struct ssh * ssh,const char * local_user,const char * server_user,char * host,Sensitive * sensitive)384 ssh_userauth2(struct ssh *ssh, const char *local_user,
385     const char *server_user, char *host, Sensitive *sensitive)
386 {
387 	Authctxt authctxt;
388 	int r;
389 
390 	if (options.challenge_response_authentication)
391 		options.kbd_interactive_authentication = 1;
392 	if (options.preferred_authentications == NULL)
393 		options.preferred_authentications = authmethods_get();
394 
395 	/* setup authentication context */
396 	memset(&authctxt, 0, sizeof(authctxt));
397 	authctxt.server_user = server_user;
398 	authctxt.local_user = local_user;
399 	authctxt.host = host;
400 	authctxt.service = "ssh-connection";		/* service name */
401 	authctxt.success = 0;
402 	authctxt.method = authmethod_lookup("none");
403 	authctxt.authlist = NULL;
404 	authctxt.methoddata = NULL;
405 	authctxt.sensitive = sensitive;
406 	authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL;
407 	authctxt.info_req_seen = 0;
408 	authctxt.attempt_kbdint = 0;
409 	authctxt.attempt_passwd = 0;
410 #if GSSAPI
411 	authctxt.gss_supported_mechs = NULL;
412 	authctxt.mech_tried = 0;
413 #endif
414 	authctxt.agent_fd = -1;
415 	pubkey_prepare(&authctxt);
416 	if (authctxt.method == NULL) {
417 		fatal("%s: internal error: cannot send userauth none request",
418 		    __func__);
419 	}
420 
421 	if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 ||
422 	    (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 ||
423 	    (r = sshpkt_send(ssh)) != 0)
424 		fatal("%s: %s", __func__, ssh_err(r));
425 
426 	ssh->authctxt = &authctxt;
427 	ssh_dispatch_init(ssh, &input_userauth_error);
428 	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info);
429 	ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept);
430 	ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success);	/* loop until success */
431 	pubkey_cleanup(ssh);
432 	ssh->authctxt = NULL;
433 
434 	ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
435 
436 	if (!authctxt.success)
437 		fatal("Authentication failed.");
438 	debug("Authentication succeeded (%s).", authctxt.method->name);
439 }
440 
441 /* ARGSUSED */
442 static int
input_userauth_service_accept(int type,u_int32_t seq,struct ssh * ssh)443 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh)
444 {
445 	int r;
446 
447 	if (ssh_packet_remaining(ssh) > 0) {
448 		char *reply;
449 
450 		if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0)
451 			goto out;
452 		debug2("service_accept: %s", reply);
453 		free(reply);
454 	} else {
455 		debug2("buggy server: service_accept w/o service");
456 	}
457 	if ((r = sshpkt_get_end(ssh)) != 0)
458 		goto out;
459 	debug("SSH2_MSG_SERVICE_ACCEPT received");
460 
461 	/* initial userauth request */
462 	userauth_none(ssh);
463 
464 	ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error);
465 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
466 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
467 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
468 	r = 0;
469  out:
470 	return r;
471 }
472 
473 /* ARGSUSED */
474 static int
input_userauth_ext_info(int type,u_int32_t seqnr,struct ssh * ssh)475 input_userauth_ext_info(int type, u_int32_t seqnr, struct ssh *ssh)
476 {
477 	return kex_input_ext_info(type, seqnr, ssh);
478 }
479 
480 void
userauth(struct ssh * ssh,char * authlist)481 userauth(struct ssh *ssh, char *authlist)
482 {
483 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
484 
485 	if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
486 		authctxt->method->cleanup(ssh);
487 
488 	free(authctxt->methoddata);
489 	authctxt->methoddata = NULL;
490 	if (authlist == NULL) {
491 		authlist = authctxt->authlist;
492 	} else {
493 		free(authctxt->authlist);
494 		authctxt->authlist = authlist;
495 	}
496 	for (;;) {
497 		Authmethod *method = authmethod_get(authlist);
498 		if (method == NULL)
499 			fatal("%s@%s: Permission denied (%s).",
500 			    authctxt->server_user, authctxt->host, authlist);
501 		authctxt->method = method;
502 
503 		/* reset the per method handler */
504 		ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN,
505 		    SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
506 
507 		/* and try new method */
508 		if (method->userauth(ssh) != 0) {
509 			debug2("we sent a %s packet, wait for reply", method->name);
510 			break;
511 		} else {
512 			debug2("we did not send a packet, disable method");
513 			method->enabled = NULL;
514 		}
515 	}
516 }
517 
518 /* ARGSUSED */
519 static int
input_userauth_error(int type,u_int32_t seq,struct ssh * ssh)520 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh)
521 {
522 	fatal("%s: bad message during authentication: type %d", __func__, type);
523 	return 0;
524 }
525 
526 /* ARGSUSED */
527 static int
input_userauth_banner(int type,u_int32_t seq,struct ssh * ssh)528 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh)
529 {
530 	char *msg = NULL;
531 	size_t len;
532 	int r;
533 
534 	debug3("%s", __func__);
535 	if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 ||
536 	    (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0)
537 		goto out;
538 	if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO)
539 		fmprintf(stderr, "%s", msg);
540 	r = 0;
541  out:
542 	free(msg);
543 	return r;
544 }
545 
546 /* ARGSUSED */
547 static int
input_userauth_success(int type,u_int32_t seq,struct ssh * ssh)548 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh)
549 {
550 	Authctxt *authctxt = ssh->authctxt;
551 
552 	if (authctxt == NULL)
553 		fatal("%s: no authentication context", __func__);
554 	free(authctxt->authlist);
555 	authctxt->authlist = NULL;
556 	if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
557 		authctxt->method->cleanup(ssh);
558 	free(authctxt->methoddata);
559 	authctxt->methoddata = NULL;
560 	authctxt->success = 1;			/* break out */
561 	return 0;
562 }
563 
564 #if 0
565 static int
566 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh)
567 {
568 	Authctxt *authctxt = ssh->authctxt;
569 
570 	if (authctxt == NULL)
571 		fatal("%s: no authentication context", __func__);
572 
573 	fatal("Unexpected authentication success during %s.",
574 	    authctxt->method->name);
575 	return 0;
576 }
577 #endif
578 
579 /* ARGSUSED */
580 static int
input_userauth_failure(int type,u_int32_t seq,struct ssh * ssh)581 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh)
582 {
583 	Authctxt *authctxt = ssh->authctxt;
584 	char *authlist = NULL;
585 	u_char partial;
586 
587 	if (authctxt == NULL)
588 		fatal("input_userauth_failure: no authentication context");
589 
590 	if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 ||
591 	    sshpkt_get_u8(ssh, &partial) != 0 ||
592 	    sshpkt_get_end(ssh) != 0)
593 		goto out;
594 
595 	if (partial != 0) {
596 		verbose("Authenticated with partial success.");
597 		/* reset state */
598 		pubkey_reset(authctxt);
599 	}
600 	debug("Authentications that can continue: %s", authlist);
601 
602 	userauth(ssh, authlist);
603 	authlist = NULL;
604  out:
605 	free(authlist);
606 	return 0;
607 }
608 
609 /*
610  * Format an identity for logging including filename, key type, fingerprint
611  * and location (agent, etc.). Caller must free.
612  */
613 static char *
format_identity(Identity * id)614 format_identity(Identity *id)
615 {
616 	char *fp = NULL, *ret = NULL;
617 	const char *note = "";
618 
619 	if (id->key != NULL) {
620 	     fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
621 		    SSH_FP_DEFAULT);
622 	}
623 	if (id->key) {
624 		if ((id->key->flags & SSHKEY_FLAG_EXT) != 0)
625 			note = " token";
626 		else if (sshkey_is_sk(id->key))
627 			note = " authenticator";
628 	}
629 	xasprintf(&ret, "%s %s%s%s%s%s%s",
630 	    id->filename,
631 	    id->key ? sshkey_type(id->key) : "", id->key ? " " : "",
632 	    fp ? fp : "",
633 	    id->userprovided ? " explicit" : "", note,
634 	    id->agent_fd != -1 ? " agent" : "");
635 	free(fp);
636 	return ret;
637 }
638 
639 /* ARGSUSED */
640 static int
input_userauth_pk_ok(int type,u_int32_t seq,struct ssh * ssh)641 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh)
642 {
643 	Authctxt *authctxt = ssh->authctxt;
644 	struct sshkey *key = NULL;
645 	Identity *id = NULL;
646 	int pktype, found = 0, sent = 0;
647 	size_t blen;
648 	char *pkalg = NULL, *fp = NULL, *ident = NULL;
649 	u_char *pkblob = NULL;
650 	int r;
651 
652 	if (authctxt == NULL)
653 		fatal("input_userauth_pk_ok: no authentication context");
654 
655 	if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 ||
656 	    (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 ||
657 	    (r = sshpkt_get_end(ssh)) != 0)
658 		goto done;
659 
660 	if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) {
661 		debug("%s: server sent unknown pkalg %s", __func__, pkalg);
662 		goto done;
663 	}
664 	if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
665 		debug("no key from blob. pkalg %s: %s", pkalg, ssh_err(r));
666 		goto done;
667 	}
668 	if (key->type != pktype) {
669 		error("input_userauth_pk_ok: type mismatch "
670 		    "for decoded key (received %d, expected %d)",
671 		    key->type, pktype);
672 		goto done;
673 	}
674 
675 	/*
676 	 * search keys in the reverse order, because last candidate has been
677 	 * moved to the end of the queue.  this also avoids confusion by
678 	 * duplicate keys
679 	 */
680 	TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
681 		if (sshkey_equal(key, id->key)) {
682 			found = 1;
683 			break;
684 		}
685 	}
686 	if (!found || id == NULL) {
687 		fp = sshkey_fingerprint(key, options.fingerprint_hash,
688 		    SSH_FP_DEFAULT);
689 		error("%s: server replied with unknown key: %s %s", __func__,
690 		    sshkey_type(key), fp == NULL ? "<ERROR>" : fp);
691 		goto done;
692 	}
693 	ident = format_identity(id);
694 	debug("Server accepts key: %s", ident);
695 	sent = sign_and_send_pubkey(ssh, id);
696 	r = 0;
697  done:
698 	sshkey_free(key);
699 	free(ident);
700 	free(fp);
701 	free(pkalg);
702 	free(pkblob);
703 
704 	/* try another method if we did not send a packet */
705 	if (r == 0 && sent == 0)
706 		userauth(ssh, NULL);
707 	return r;
708 }
709 
710 #ifdef GSSAPI
711 static int
userauth_gssapi(struct ssh * ssh)712 userauth_gssapi(struct ssh *ssh)
713 {
714 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
715 	Gssctxt *gssctxt = NULL;
716 	OM_uint32 min;
717 	int r, ok = 0;
718 	gss_OID mech = NULL;
719 
720 	/* Try one GSSAPI method at a time, rather than sending them all at
721 	 * once. */
722 
723 	if (authctxt->gss_supported_mechs == NULL)
724 		gss_indicate_mechs(&min, &authctxt->gss_supported_mechs);
725 
726 	/* Check to see whether the mechanism is usable before we offer it */
727 	while (authctxt->mech_tried < authctxt->gss_supported_mechs->count &&
728 	    !ok) {
729 		mech = &authctxt->gss_supported_mechs->
730 		    elements[authctxt->mech_tried];
731 		/* My DER encoding requires length<128 */
732 		if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt,
733 		    mech, authctxt->host)) {
734 			ok = 1; /* Mechanism works */
735 		} else {
736 			authctxt->mech_tried++;
737 		}
738 	}
739 
740 	if (!ok || mech == NULL)
741 		return 0;
742 
743 	authctxt->methoddata=(void *)gssctxt;
744 
745 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
746 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
747 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
748 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
749 	    (r = sshpkt_put_u32(ssh, 1)) != 0 ||
750 	    (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 ||
751 	    (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 ||
752 	    (r = sshpkt_put_u8(ssh, mech->length)) != 0 ||
753 	    (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 ||
754 	    (r = sshpkt_send(ssh)) != 0)
755 		fatal("%s: %s", __func__, ssh_err(r));
756 
757 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
758 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
759 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
760 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
761 
762 	authctxt->mech_tried++; /* Move along to next candidate */
763 
764 	return 1;
765 }
766 
767 static void
userauth_gssapi_cleanup(struct ssh * ssh)768 userauth_gssapi_cleanup(struct ssh *ssh)
769 {
770 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
771 	Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata;
772 
773 	ssh_gssapi_delete_ctx(&gssctxt);
774 	authctxt->methoddata = NULL;
775 
776 	free(authctxt->gss_supported_mechs);
777 	authctxt->gss_supported_mechs = NULL;
778 }
779 
780 static OM_uint32
process_gssapi_token(struct ssh * ssh,gss_buffer_t recv_tok)781 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok)
782 {
783 	Authctxt *authctxt = ssh->authctxt;
784 	Gssctxt *gssctxt = authctxt->methoddata;
785 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
786 	gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
787 	gss_buffer_desc gssbuf;
788 	OM_uint32 status, ms, flags;
789 	int r;
790 
791 	status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
792 	    recv_tok, &send_tok, &flags);
793 
794 	if (send_tok.length > 0) {
795 		u_char type = GSS_ERROR(status) ?
796 		    SSH2_MSG_USERAUTH_GSSAPI_ERRTOK :
797 		    SSH2_MSG_USERAUTH_GSSAPI_TOKEN;
798 
799 		if ((r = sshpkt_start(ssh, type)) != 0 ||
800 		    (r = sshpkt_put_string(ssh, send_tok.value,
801 		    send_tok.length)) != 0 ||
802 		    (r = sshpkt_send(ssh)) != 0)
803 			fatal("%s: %s", __func__, ssh_err(r));
804 
805 		gss_release_buffer(&ms, &send_tok);
806 	}
807 
808 	if (status == GSS_S_COMPLETE) {
809 		/* send either complete or MIC, depending on mechanism */
810 		if (!(flags & GSS_C_INTEG_FLAG)) {
811 			if ((r = sshpkt_start(ssh,
812 			    SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 ||
813 			    (r = sshpkt_send(ssh)) != 0)
814 				fatal("%s: %s", __func__, ssh_err(r));
815 		} else {
816 			struct sshbuf *b;
817 
818 			if ((b = sshbuf_new()) == NULL)
819 				fatal("%s: sshbuf_new failed", __func__);
820 			ssh_gssapi_buildmic(b, authctxt->server_user,
821 			    authctxt->service, "gssapi-with-mic");
822 
823 			if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
824 				fatal("%s: sshbuf_mutable_ptr failed", __func__);
825 			gssbuf.length = sshbuf_len(b);
826 
827 			status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
828 
829 			if (!GSS_ERROR(status)) {
830 				if ((r = sshpkt_start(ssh,
831 				    SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 ||
832 				    (r = sshpkt_put_string(ssh, mic.value,
833 				    mic.length)) != 0 ||
834 				    (r = sshpkt_send(ssh)) != 0)
835 					fatal("%s: %s", __func__, ssh_err(r));
836 			}
837 
838 			sshbuf_free(b);
839 			gss_release_buffer(&ms, &mic);
840 		}
841 	}
842 
843 	return status;
844 }
845 
846 /* ARGSUSED */
847 static int
input_gssapi_response(int type,u_int32_t plen,struct ssh * ssh)848 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh)
849 {
850 	Authctxt *authctxt = ssh->authctxt;
851 	Gssctxt *gssctxt;
852 	size_t oidlen;
853 	u_char *oidv = NULL;
854 	int r;
855 
856 	if (authctxt == NULL)
857 		fatal("input_gssapi_response: no authentication context");
858 	gssctxt = authctxt->methoddata;
859 
860 	/* Setup our OID */
861 	if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0)
862 		goto done;
863 
864 	if (oidlen <= 2 ||
865 	    oidv[0] != SSH_GSS_OIDTYPE ||
866 	    oidv[1] != oidlen - 2) {
867 		debug("Badly encoded mechanism OID received");
868 		userauth(ssh, NULL);
869 		goto ok;
870 	}
871 
872 	if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
873 		fatal("Server returned different OID than expected");
874 
875 	if ((r = sshpkt_get_end(ssh)) != 0)
876 		goto done;
877 
878 	if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) {
879 		/* Start again with next method on list */
880 		debug("Trying to start again");
881 		userauth(ssh, NULL);
882 		goto ok;
883 	}
884  ok:
885 	r = 0;
886  done:
887 	free(oidv);
888 	return r;
889 }
890 
891 /* ARGSUSED */
892 static int
input_gssapi_token(int type,u_int32_t plen,struct ssh * ssh)893 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh)
894 {
895 	Authctxt *authctxt = ssh->authctxt;
896 	gss_buffer_desc recv_tok;
897 	u_char *p = NULL;
898 	size_t len;
899 	OM_uint32 status;
900 	int r;
901 
902 	if (authctxt == NULL)
903 		fatal("input_gssapi_response: no authentication context");
904 
905 	if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
906 	    (r = sshpkt_get_end(ssh)) != 0)
907 		goto out;
908 
909 	recv_tok.value = p;
910 	recv_tok.length = len;
911 	status = process_gssapi_token(ssh, &recv_tok);
912 
913 	/* Start again with the next method in the list */
914 	if (GSS_ERROR(status)) {
915 		userauth(ssh, NULL);
916 		/* ok */
917 	}
918 	r = 0;
919  out:
920 	free(p);
921 	return r;
922 }
923 
924 /* ARGSUSED */
925 static int
input_gssapi_errtok(int type,u_int32_t plen,struct ssh * ssh)926 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh)
927 {
928 	Authctxt *authctxt = ssh->authctxt;
929 	Gssctxt *gssctxt;
930 	gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
931 	gss_buffer_desc recv_tok;
932 	OM_uint32 ms;
933 	u_char *p = NULL;
934 	size_t len;
935 	int r;
936 
937 	if (authctxt == NULL)
938 		fatal("input_gssapi_response: no authentication context");
939 	gssctxt = authctxt->methoddata;
940 
941 	if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
942 	    (r = sshpkt_get_end(ssh)) != 0) {
943 		free(p);
944 		return r;
945 	}
946 
947 	/* Stick it into GSSAPI and see what it says */
948 	recv_tok.value = p;
949 	recv_tok.length = len;
950 	(void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
951 	    &recv_tok, &send_tok, NULL);
952 	free(p);
953 	gss_release_buffer(&ms, &send_tok);
954 
955 	/* Server will be returning a failed packet after this one */
956 	return 0;
957 }
958 
959 /* ARGSUSED */
960 static int
input_gssapi_error(int type,u_int32_t plen,struct ssh * ssh)961 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
962 {
963 	char *msg = NULL;
964 	char *lang = NULL;
965 	int r;
966 
967 	if ((r = sshpkt_get_u32(ssh, NULL)) != 0 ||	/* maj */
968 	    (r = sshpkt_get_u32(ssh, NULL)) != 0 ||	/* min */
969 	    (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 ||
970 	    (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
971 		goto out;
972 	r = sshpkt_get_end(ssh);
973 	debug("Server GSSAPI Error:\n%s", msg);
974  out:
975 	free(msg);
976 	free(lang);
977 	return r;
978 }
979 #endif /* GSSAPI */
980 
981 static int
userauth_none(struct ssh * ssh)982 userauth_none(struct ssh *ssh)
983 {
984 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
985 	int r;
986 
987 	/* initial userauth request */
988 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
989 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
990 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
991 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
992 	    (r = sshpkt_send(ssh)) != 0)
993 		fatal("%s: %s", __func__, ssh_err(r));
994 	return 1;
995 }
996 
997 static int
userauth_passwd(struct ssh * ssh)998 userauth_passwd(struct ssh *ssh)
999 {
1000 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1001 	char *password, *prompt = NULL;
1002 	const char *host = options.host_key_alias ?  options.host_key_alias :
1003 	    authctxt->host;
1004 	int r;
1005 
1006 	if (authctxt->attempt_passwd++ >= options.number_of_password_prompts)
1007 		return 0;
1008 
1009 	if (authctxt->attempt_passwd != 1)
1010 		error("Permission denied, please try again.");
1011 
1012 	xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host);
1013 	password = read_passphrase(prompt, 0);
1014 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1015 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1016 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1017 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1018 	    (r = sshpkt_put_u8(ssh, 0)) != 0 ||
1019 	    (r = sshpkt_put_cstring(ssh, password)) != 0 ||
1020 	    (r = sshpkt_add_padding(ssh, 64)) != 0 ||
1021 	    (r = sshpkt_send(ssh)) != 0)
1022 		fatal("%s: %s", __func__, ssh_err(r));
1023 
1024 	free(prompt);
1025 	if (password != NULL)
1026 		freezero(password, strlen(password));
1027 
1028 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1029 	    &input_userauth_passwd_changereq);
1030 
1031 	return 1;
1032 }
1033 
1034 /*
1035  * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
1036  */
1037 /* ARGSUSED */
1038 static int
input_userauth_passwd_changereq(int type,u_int32_t seqnr,struct ssh * ssh)1039 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh)
1040 {
1041 	Authctxt *authctxt = ssh->authctxt;
1042 	char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL;
1043 	char prompt[256];
1044 	const char *host;
1045 	int r;
1046 
1047 	debug2("input_userauth_passwd_changereq");
1048 
1049 	if (authctxt == NULL)
1050 		fatal("input_userauth_passwd_changereq: "
1051 		    "no authentication context");
1052 	host = options.host_key_alias ? options.host_key_alias : authctxt->host;
1053 
1054 	if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 ||
1055 	    (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
1056 		goto out;
1057 	if (strlen(info) > 0)
1058 		logit("%s", info);
1059 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1060 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1061 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1062 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1063 	    (r = sshpkt_put_u8(ssh, 1)) != 0)	/* additional info */
1064 		goto out;
1065 
1066 	snprintf(prompt, sizeof(prompt),
1067 	    "Enter %.30s@%.128s's old password: ",
1068 	    authctxt->server_user, host);
1069 	password = read_passphrase(prompt, 0);
1070 	if ((r = sshpkt_put_cstring(ssh, password)) != 0)
1071 		goto out;
1072 
1073 	freezero(password, strlen(password));
1074 	password = NULL;
1075 	while (password == NULL) {
1076 		snprintf(prompt, sizeof(prompt),
1077 		    "Enter %.30s@%.128s's new password: ",
1078 		    authctxt->server_user, host);
1079 		password = read_passphrase(prompt, RP_ALLOW_EOF);
1080 		if (password == NULL) {
1081 			/* bail out */
1082 			r = 0;
1083 			goto out;
1084 		}
1085 		snprintf(prompt, sizeof(prompt),
1086 		    "Retype %.30s@%.128s's new password: ",
1087 		    authctxt->server_user, host);
1088 		retype = read_passphrase(prompt, 0);
1089 		if (strcmp(password, retype) != 0) {
1090 			freezero(password, strlen(password));
1091 			logit("Mismatch; try again, EOF to quit.");
1092 			password = NULL;
1093 		}
1094 		freezero(retype, strlen(retype));
1095 	}
1096 	if ((r = sshpkt_put_cstring(ssh, password)) != 0 ||
1097 	    (r = sshpkt_add_padding(ssh, 64)) != 0 ||
1098 	    (r = sshpkt_send(ssh)) != 0)
1099 		goto out;
1100 
1101 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1102 	    &input_userauth_passwd_changereq);
1103 	r = 0;
1104  out:
1105 	if (password)
1106 		freezero(password, strlen(password));
1107 	free(info);
1108 	free(lang);
1109 	return r;
1110 }
1111 
1112 /*
1113  * Select an algorithm for publickey signatures.
1114  * Returns algorithm (caller must free) or NULL if no mutual algorithm found.
1115  *
1116  * Call with ssh==NULL to ignore server-sig-algs extension list and
1117  * only attempt with the key's base signature type.
1118  */
1119 static char *
key_sig_algorithm(struct ssh * ssh,const struct sshkey * key)1120 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key)
1121 {
1122 	char *allowed, *oallowed, *cp, *tmp, *alg = NULL;
1123 
1124 	/*
1125 	 * The signature algorithm will only differ from the key algorithm
1126 	 * for RSA keys/certs and when the server advertises support for
1127 	 * newer (SHA2) algorithms.
1128 	 */
1129 	if (ssh == NULL || ssh->kex->server_sig_algs == NULL ||
1130 	    (key->type != KEY_RSA && key->type != KEY_RSA_CERT) ||
1131 	    (key->type == KEY_RSA_CERT && (datafellows & SSH_BUG_SIGTYPE))) {
1132 		/* Filter base key signature alg against our configuration */
1133 		return match_list(sshkey_ssh_name(key),
1134 		    options.pubkey_key_types, NULL);
1135 	}
1136 
1137 	/*
1138 	 * For RSA keys/certs, since these might have a different sig type:
1139 	 * find the first entry in PubkeyAcceptedKeyTypes of the right type
1140 	 * that also appears in the supported signature algorithms list from
1141 	 * the server.
1142 	 */
1143 	oallowed = allowed = xstrdup(options.pubkey_key_types);
1144 	while ((cp = strsep(&allowed, ",")) != NULL) {
1145 		if (sshkey_type_from_name(cp) != key->type)
1146 			continue;
1147 		tmp = match_list(sshkey_sigalg_by_name(cp), ssh->kex->server_sig_algs, NULL);
1148 		if (tmp != NULL)
1149 			alg = xstrdup(cp);
1150 		free(tmp);
1151 		if (alg != NULL)
1152 			break;
1153 	}
1154 	free(oallowed);
1155 	return alg;
1156 }
1157 
1158 static int
identity_sign(struct identity * id,u_char ** sigp,size_t * lenp,const u_char * data,size_t datalen,u_int compat,const char * alg)1159 identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
1160     const u_char *data, size_t datalen, u_int compat, const char *alg)
1161 {
1162 	struct sshkey *sign_key = NULL, *prv = NULL;
1163 	int r = SSH_ERR_INTERNAL_ERROR;
1164 	struct notifier_ctx *notifier = NULL;
1165 	char *fp = NULL;
1166 
1167 	*sigp = NULL;
1168 	*lenp = 0;
1169 
1170 	/* The agent supports this key. */
1171 	if (id->key != NULL && id->agent_fd != -1) {
1172 		return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp,
1173 		    data, datalen, alg, compat);
1174 	}
1175 
1176 	/*
1177 	 * We have already loaded the private key or the private key is
1178 	 * stored in external hardware.
1179 	 */
1180 	if (id->key != NULL &&
1181 	    (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) {
1182 		sign_key = id->key;
1183 	} else {
1184 		/* Load the private key from the file. */
1185 		if ((prv = load_identity_file(id)) == NULL)
1186 			return SSH_ERR_KEY_NOT_FOUND;
1187 		if (id->key != NULL && !sshkey_equal_public(prv, id->key)) {
1188 			error("%s: private key %s contents do not match public",
1189 			   __func__, id->filename);
1190 			r = SSH_ERR_KEY_NOT_FOUND;
1191 			goto out;
1192 		}
1193 		sign_key = prv;
1194 		if (sshkey_is_sk(sign_key) &&
1195 		    (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) {
1196 			/* XXX match batch mode should just skip these keys? */
1197 			if ((fp = sshkey_fingerprint(sign_key,
1198 			    options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
1199 				fatal("%s: sshkey_fingerprint", __func__);
1200 			notifier = notify_start(options.batch_mode,
1201 			    "Confirm user presence for key %s %s",
1202 			    sshkey_type(sign_key), fp);
1203 			free(fp);
1204 		}
1205 	}
1206 	if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen,
1207 	    alg, options.sk_provider, compat)) != 0) {
1208 		debug("%s: sshkey_sign: %s", __func__, ssh_err(r));
1209 		goto out;
1210 	}
1211 	/*
1212 	 * PKCS#11 tokens may not support all signature algorithms,
1213 	 * so check what we get back.
1214 	 */
1215 	if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) {
1216 		debug("%s: sshkey_check_sigtype: %s", __func__, ssh_err(r));
1217 		goto out;
1218 	}
1219 	/* success */
1220 	r = 0;
1221  out:
1222 	notify_complete(notifier);
1223 	sshkey_free(prv);
1224 	return r;
1225 }
1226 
1227 static int
id_filename_matches(Identity * id,Identity * private_id)1228 id_filename_matches(Identity *id, Identity *private_id)
1229 {
1230 	const char *suffixes[] = { ".pub", "-cert.pub", NULL };
1231 	size_t len = strlen(id->filename), plen = strlen(private_id->filename);
1232 	size_t i, slen;
1233 
1234 	if (strcmp(id->filename, private_id->filename) == 0)
1235 		return 1;
1236 	for (i = 0; suffixes[i]; i++) {
1237 		slen = strlen(suffixes[i]);
1238 		if (len > slen && plen == len - slen &&
1239 		    strcmp(id->filename + (len - slen), suffixes[i]) == 0 &&
1240 		    memcmp(id->filename, private_id->filename, plen) == 0)
1241 			return 1;
1242 	}
1243 	return 0;
1244 }
1245 
1246 static int
sign_and_send_pubkey(struct ssh * ssh,Identity * id)1247 sign_and_send_pubkey(struct ssh *ssh, Identity *id)
1248 {
1249 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1250 	struct sshbuf *b = NULL;
1251 	Identity *private_id, *sign_id = NULL;
1252 	u_char *signature = NULL;
1253 	size_t slen = 0, skip = 0;
1254 	int r, fallback_sigtype, sent = 0;
1255 	char *alg = NULL, *fp = NULL;
1256 	const char *loc = "";
1257 
1258 	if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
1259 	    SSH_FP_DEFAULT)) == NULL)
1260 		return 0;
1261 
1262 	debug3("%s: %s %s", __func__, sshkey_type(id->key), fp);
1263 
1264 	/*
1265 	 * If the key is an certificate, try to find a matching private key
1266 	 * and use it to complete the signature.
1267 	 * If no such private key exists, fall back to trying the certificate
1268 	 * key itself in case it has a private half already loaded.
1269 	 * This will try to set sign_id to the private key that will perform
1270 	 * the signature.
1271 	 */
1272 	if (sshkey_is_cert(id->key)) {
1273 		TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1274 			if (sshkey_equal_public(id->key, private_id->key) &&
1275 			    id->key->type != private_id->key->type) {
1276 				sign_id = private_id;
1277 				break;
1278 			}
1279 		}
1280 		/*
1281 		 * Exact key matches are preferred, but also allow
1282 		 * filename matches for non-PKCS#11/agent keys that
1283 		 * didn't load public keys. This supports the case
1284 		 * of keeping just a private key file and public
1285 		 * certificate on disk.
1286 		 */
1287 		if (sign_id == NULL &&
1288 		    !id->isprivate && id->agent_fd == -1 &&
1289 		    (id->key->flags & SSHKEY_FLAG_EXT) == 0) {
1290 			TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1291 				if (private_id->key == NULL &&
1292 				    id_filename_matches(id, private_id)) {
1293 					sign_id = private_id;
1294 					break;
1295 				}
1296 			}
1297 		}
1298 		if (sign_id != NULL) {
1299 			debug2("%s: using private key \"%s\"%s for "
1300 			    "certificate", __func__, id->filename,
1301 			    id->agent_fd != -1 ? " from agent" : "");
1302 		} else {
1303 			debug("%s: no separate private key for certificate "
1304 			    "\"%s\"", __func__, id->filename);
1305 		}
1306 	}
1307 
1308 	/*
1309 	 * If the above didn't select another identity to do the signing
1310 	 * then default to the one we started with.
1311 	 */
1312 	if (sign_id == NULL)
1313 		sign_id = id;
1314 
1315 	/* assemble and sign data */
1316 	for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) {
1317 		free(alg);
1318 		slen = 0;
1319 		signature = NULL;
1320 		if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh,
1321 		    id->key)) == NULL) {
1322 			error("%s: no mutual signature supported", __func__);
1323 			goto out;
1324 		}
1325 		debug3("%s: signing using %s %s", __func__, alg, fp);
1326 
1327 		sshbuf_free(b);
1328 		if ((b = sshbuf_new()) == NULL)
1329 			fatal("%s: sshbuf_new failed", __func__);
1330 		if (datafellows & SSH_OLD_SESSIONID) {
1331 			if ((r = sshbuf_put(b, session_id2,
1332 			    session_id2_len)) != 0) {
1333 				fatal("%s: sshbuf_put: %s",
1334 				    __func__, ssh_err(r));
1335 			}
1336 		} else {
1337 			if ((r = sshbuf_put_string(b, session_id2,
1338 			    session_id2_len)) != 0) {
1339 				fatal("%s: sshbuf_put_string: %s",
1340 				    __func__, ssh_err(r));
1341 			}
1342 		}
1343 		skip = sshbuf_len(b);
1344 		if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1345 		    (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
1346 		    (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
1347 		    (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
1348 		    (r = sshbuf_put_u8(b, 1)) != 0 ||
1349 		    (r = sshbuf_put_cstring(b, alg)) != 0 ||
1350 		    (r = sshkey_puts(id->key, b)) != 0) {
1351 			fatal("%s: assemble signed data: %s",
1352 			    __func__, ssh_err(r));
1353 		}
1354 
1355 		/* generate signature */
1356 		r = identity_sign(sign_id, &signature, &slen,
1357 		    sshbuf_ptr(b), sshbuf_len(b), datafellows, alg);
1358 		if (r == 0)
1359 			break;
1360 		else if (r == SSH_ERR_KEY_NOT_FOUND)
1361 			goto out; /* soft failure */
1362 		else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED &&
1363 		    !fallback_sigtype) {
1364 			if (sign_id->agent_fd != -1)
1365 				loc = "agent ";
1366 			else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0)
1367 				loc = "token ";
1368 			logit("%skey %s %s returned incorrect signature type",
1369 			    loc, sshkey_type(id->key), fp);
1370 			continue;
1371 		}
1372 		error("%s: signing failed for %s \"%s\"%s: %s", __func__,
1373 		    sshkey_type(sign_id->key), sign_id->filename,
1374 		    id->agent_fd != -1 ? " from agent" : "", ssh_err(r));
1375 		goto out;
1376 	}
1377 	if (slen == 0 || signature == NULL) /* shouldn't happen */
1378 		fatal("%s: no signature", __func__);
1379 
1380 	/* append signature */
1381 	if ((r = sshbuf_put_string(b, signature, slen)) != 0)
1382 		fatal("%s: append signature: %s", __func__, ssh_err(r));
1383 
1384 #ifdef DEBUG_PK
1385 	sshbuf_dump(b, stderr);
1386 #endif
1387 	/* skip session id and packet type */
1388 	if ((r = sshbuf_consume(b, skip + 1)) != 0)
1389 		fatal("%s: consume: %s", __func__, ssh_err(r));
1390 
1391 	/* put remaining data from buffer into packet */
1392 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1393 	    (r = sshpkt_putb(ssh, b)) != 0 ||
1394 	    (r = sshpkt_send(ssh)) != 0)
1395 		fatal("%s: enqueue request: %s", __func__, ssh_err(r));
1396 
1397 	/* success */
1398 	sent = 1;
1399 
1400  out:
1401 	free(fp);
1402 	free(alg);
1403 	sshbuf_free(b);
1404 	freezero(signature, slen);
1405 	return sent;
1406 }
1407 
1408 static int
send_pubkey_test(struct ssh * ssh,Identity * id)1409 send_pubkey_test(struct ssh *ssh, Identity *id)
1410 {
1411 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1412 	u_char *blob = NULL;
1413 	char *alg = NULL;
1414 	size_t bloblen;
1415 	u_int have_sig = 0;
1416 	int sent = 0, r;
1417 
1418 	if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) {
1419 		debug("%s: no mutual signature algorithm", __func__);
1420 		goto out;
1421 	}
1422 
1423 	if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) {
1424 		/* we cannot handle this key */
1425 		debug3("%s: cannot handle key", __func__);
1426 		goto out;
1427 	}
1428 	/* register callback for USERAUTH_PK_OK message */
1429 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1430 
1431 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1432 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1433 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1434 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1435 	    (r = sshpkt_put_u8(ssh, have_sig)) != 0 ||
1436 	    (r = sshpkt_put_cstring(ssh, alg)) != 0 ||
1437 	    (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 ||
1438 	    (r = sshpkt_send(ssh)) != 0)
1439 		fatal("%s: %s", __func__, ssh_err(r));
1440 	sent = 1;
1441 
1442  out:
1443 	free(alg);
1444 	free(blob);
1445 	return sent;
1446 }
1447 
1448 static struct sshkey *
load_identity_file(Identity * id)1449 load_identity_file(Identity *id)
1450 {
1451 	struct sshkey *private = NULL;
1452 	char prompt[300], *passphrase, *comment;
1453 	int r, quit = 0, i;
1454 	struct stat st;
1455 
1456 	if (stat(id->filename, &st) == -1) {
1457 		(id->userprovided ? logit : debug3)("no such identity: %s: %s",
1458 		    id->filename, strerror(errno));
1459 		return NULL;
1460 	}
1461 	snprintf(prompt, sizeof prompt,
1462 	    "Enter passphrase for key '%.100s': ", id->filename);
1463 	for (i = 0; i <= options.number_of_password_prompts; i++) {
1464 		if (i == 0)
1465 			passphrase = "";
1466 		else {
1467 			passphrase = read_passphrase(prompt, 0);
1468 			if (*passphrase == '\0') {
1469 				debug2("no passphrase given, try next key");
1470 				free(passphrase);
1471 				break;
1472 			}
1473 		}
1474 		switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename,
1475 		    passphrase, &private, &comment))) {
1476 		case 0:
1477 			break;
1478 		case SSH_ERR_KEY_WRONG_PASSPHRASE:
1479 			if (options.batch_mode) {
1480 				quit = 1;
1481 				break;
1482 			}
1483 			if (i != 0)
1484 				debug2("bad passphrase given, try again...");
1485 			break;
1486 		case SSH_ERR_SYSTEM_ERROR:
1487 			if (errno == ENOENT) {
1488 				debug2("Load key \"%s\": %s",
1489 				    id->filename, ssh_err(r));
1490 				quit = 1;
1491 				break;
1492 			}
1493 			/* FALLTHROUGH */
1494 		default:
1495 			error("Load key \"%s\": %s", id->filename, ssh_err(r));
1496 			quit = 1;
1497 			break;
1498 		}
1499 		if (private != NULL && sshkey_is_sk(private) &&
1500 		    options.sk_provider == NULL) {
1501 			debug("key \"%s\" is an authenticator-hosted key, "
1502 			    "but no provider specified", id->filename);
1503 			sshkey_free(private);
1504 			private = NULL;
1505 			quit = 1;
1506 		}
1507 		if (!quit && private != NULL && id->agent_fd == -1 &&
1508 		    !(id->key && id->isprivate))
1509 			maybe_add_key_to_agent(id->filename, private, comment,
1510 			    passphrase);
1511 		if (i > 0)
1512 			freezero(passphrase, strlen(passphrase));
1513 		free(comment);
1514 		if (private != NULL || quit)
1515 			break;
1516 	}
1517 	return private;
1518 }
1519 
1520 static int
key_type_allowed_by_config(struct sshkey * key)1521 key_type_allowed_by_config(struct sshkey *key)
1522 {
1523 	if (match_pattern_list(sshkey_ssh_name(key),
1524 	    options.pubkey_key_types, 0) == 1)
1525 		return 1;
1526 
1527 	/* RSA keys/certs might be allowed by alternate signature types */
1528 	switch (key->type) {
1529 	case KEY_RSA:
1530 		if (match_pattern_list("rsa-sha2-512",
1531 		    options.pubkey_key_types, 0) == 1)
1532 			return 1;
1533 		if (match_pattern_list("rsa-sha2-256",
1534 		    options.pubkey_key_types, 0) == 1)
1535 			return 1;
1536 		break;
1537 	case KEY_RSA_CERT:
1538 		if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com",
1539 		    options.pubkey_key_types, 0) == 1)
1540 			return 1;
1541 		if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com",
1542 		    options.pubkey_key_types, 0) == 1)
1543 			return 1;
1544 		break;
1545 	}
1546 	return 0;
1547 }
1548 
1549 
1550 /*
1551  * try keys in the following order:
1552  * 	1. certificates listed in the config file
1553  * 	2. other input certificates
1554  *	3. agent keys that are found in the config file
1555  *	4. other agent keys
1556  *	5. keys that are only listed in the config file
1557  */
1558 static void
pubkey_prepare(Authctxt * authctxt)1559 pubkey_prepare(Authctxt *authctxt)
1560 {
1561 	struct identity *id, *id2, *tmp;
1562 	struct idlist agent, files, *preferred;
1563 	struct sshkey *key;
1564 	int agent_fd = -1, i, r, found;
1565 	size_t j;
1566 	struct ssh_identitylist *idlist;
1567 	char *ident;
1568 
1569 	TAILQ_INIT(&agent);	/* keys from the agent */
1570 	TAILQ_INIT(&files);	/* keys from the config file */
1571 	preferred = &authctxt->keys;
1572 	TAILQ_INIT(preferred);	/* preferred order of keys */
1573 
1574 	/* list of keys stored in the filesystem and PKCS#11 */
1575 	for (i = 0; i < options.num_identity_files; i++) {
1576 		key = options.identity_keys[i];
1577 		if (key && key->cert &&
1578 		    key->cert->type != SSH2_CERT_TYPE_USER) {
1579 			debug("%s: ignoring certificate %s: not a user "
1580 			    "certificate",  __func__,
1581 			    options.identity_files[i]);
1582 			continue;
1583 		}
1584 		if (key && sshkey_is_sk(key) && options.sk_provider == NULL) {
1585 			debug("%s: ignoring authenticator-hosted key %s as no "
1586 			    "SecurityKeyProvider has been specified",
1587 			    __func__, options.identity_files[i]);
1588 			continue;
1589 		}
1590 		options.identity_keys[i] = NULL;
1591 		id = xcalloc(1, sizeof(*id));
1592 		id->agent_fd = -1;
1593 		id->key = key;
1594 		id->filename = xstrdup(options.identity_files[i]);
1595 		id->userprovided = options.identity_file_userprovided[i];
1596 		TAILQ_INSERT_TAIL(&files, id, next);
1597 	}
1598 	/* list of certificates specified by user */
1599 	for (i = 0; i < options.num_certificate_files; i++) {
1600 		key = options.certificates[i];
1601 		if (!sshkey_is_cert(key) || key->cert == NULL ||
1602 		    key->cert->type != SSH2_CERT_TYPE_USER) {
1603 			debug("%s: ignoring certificate %s: not a user "
1604 			    "certificate",  __func__,
1605 			    options.identity_files[i]);
1606 			continue;
1607 		}
1608 		if (key && sshkey_is_sk(key) && options.sk_provider == NULL) {
1609 			debug("%s: ignoring authenticator-hosted key "
1610 			    "certificate %s as no "
1611 			    "SecurityKeyProvider has been specified",
1612 			    __func__, options.identity_files[i]);
1613 			continue;
1614 		}
1615 		id = xcalloc(1, sizeof(*id));
1616 		id->agent_fd = -1;
1617 		id->key = key;
1618 		id->filename = xstrdup(options.certificate_files[i]);
1619 		id->userprovided = options.certificate_file_userprovided[i];
1620 		TAILQ_INSERT_TAIL(preferred, id, next);
1621 	}
1622 	/* list of keys supported by the agent */
1623 	if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) {
1624 		if (r != SSH_ERR_AGENT_NOT_PRESENT)
1625 			debug("%s: ssh_get_authentication_socket: %s",
1626 			    __func__, ssh_err(r));
1627 	} else if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) {
1628 		if (r != SSH_ERR_AGENT_NO_IDENTITIES)
1629 			debug("%s: ssh_fetch_identitylist: %s",
1630 			    __func__, ssh_err(r));
1631 		close(agent_fd);
1632 	} else {
1633 		for (j = 0; j < idlist->nkeys; j++) {
1634 			found = 0;
1635 			TAILQ_FOREACH(id, &files, next) {
1636 				/*
1637 				 * agent keys from the config file are
1638 				 * preferred
1639 				 */
1640 				if (sshkey_equal(idlist->keys[j], id->key)) {
1641 					TAILQ_REMOVE(&files, id, next);
1642 					TAILQ_INSERT_TAIL(preferred, id, next);
1643 					id->agent_fd = agent_fd;
1644 					found = 1;
1645 					break;
1646 				}
1647 			}
1648 			if (!found && !options.identities_only) {
1649 				id = xcalloc(1, sizeof(*id));
1650 				/* XXX "steals" key/comment from idlist */
1651 				id->key = idlist->keys[j];
1652 				id->filename = idlist->comments[j];
1653 				idlist->keys[j] = NULL;
1654 				idlist->comments[j] = NULL;
1655 				id->agent_fd = agent_fd;
1656 				TAILQ_INSERT_TAIL(&agent, id, next);
1657 			}
1658 		}
1659 		ssh_free_identitylist(idlist);
1660 		/* append remaining agent keys */
1661 		for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1662 			TAILQ_REMOVE(&agent, id, next);
1663 			TAILQ_INSERT_TAIL(preferred, id, next);
1664 		}
1665 		authctxt->agent_fd = agent_fd;
1666 	}
1667 	/* Prefer PKCS11 keys that are explicitly listed */
1668 	TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1669 		if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0)
1670 			continue;
1671 		found = 0;
1672 		TAILQ_FOREACH(id2, &files, next) {
1673 			if (id2->key == NULL ||
1674 			    (id2->key->flags & SSHKEY_FLAG_EXT) == 0)
1675 				continue;
1676 			if (sshkey_equal(id->key, id2->key)) {
1677 				TAILQ_REMOVE(&files, id, next);
1678 				TAILQ_INSERT_TAIL(preferred, id, next);
1679 				found = 1;
1680 				break;
1681 			}
1682 		}
1683 		/* If IdentitiesOnly set and key not found then don't use it */
1684 		if (!found && options.identities_only) {
1685 			TAILQ_REMOVE(&files, id, next);
1686 			freezero(id, sizeof(*id));
1687 		}
1688 	}
1689 	/* append remaining keys from the config file */
1690 	for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1691 		TAILQ_REMOVE(&files, id, next);
1692 		TAILQ_INSERT_TAIL(preferred, id, next);
1693 	}
1694 	/* finally, filter by PubkeyAcceptedKeyTypes */
1695 	TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
1696 		if (id->key != NULL && !key_type_allowed_by_config(id->key)) {
1697 			debug("Skipping %s key %s - "
1698 			    "not in PubkeyAcceptedKeyTypes",
1699 			    sshkey_ssh_name(id->key), id->filename);
1700 			TAILQ_REMOVE(preferred, id, next);
1701 			sshkey_free(id->key);
1702 			free(id->filename);
1703 			memset(id, 0, sizeof(*id));
1704 			continue;
1705 		}
1706 	}
1707 	/* List the keys we plan on using */
1708 	TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
1709 		ident = format_identity(id);
1710 		debug("Will attempt key: %s", ident);
1711 		free(ident);
1712 	}
1713 	debug2("%s: done", __func__);
1714 }
1715 
1716 static void
pubkey_cleanup(struct ssh * ssh)1717 pubkey_cleanup(struct ssh *ssh)
1718 {
1719 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1720 	Identity *id;
1721 
1722 	if (authctxt->agent_fd != -1) {
1723 		ssh_close_authentication_socket(authctxt->agent_fd);
1724 		authctxt->agent_fd = -1;
1725 	}
1726 	for (id = TAILQ_FIRST(&authctxt->keys); id;
1727 	    id = TAILQ_FIRST(&authctxt->keys)) {
1728 		TAILQ_REMOVE(&authctxt->keys, id, next);
1729 		sshkey_free(id->key);
1730 		free(id->filename);
1731 		free(id);
1732 	}
1733 }
1734 
1735 static void
pubkey_reset(Authctxt * authctxt)1736 pubkey_reset(Authctxt *authctxt)
1737 {
1738 	Identity *id;
1739 
1740 	TAILQ_FOREACH(id, &authctxt->keys, next)
1741 		id->tried = 0;
1742 }
1743 
1744 static int
try_identity(Identity * id)1745 try_identity(Identity *id)
1746 {
1747 	if (!id->key)
1748 		return (0);
1749 	if (sshkey_type_plain(id->key->type) == KEY_RSA &&
1750 	    (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1751 		debug("Skipped %s key %s for RSA/MD5 server",
1752 		    sshkey_type(id->key), id->filename);
1753 		return (0);
1754 	}
1755 	return 1;
1756 }
1757 
1758 static int
userauth_pubkey(struct ssh * ssh)1759 userauth_pubkey(struct ssh *ssh)
1760 {
1761 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1762 	Identity *id;
1763 	int sent = 0;
1764 	char *ident;
1765 
1766 	while ((id = TAILQ_FIRST(&authctxt->keys))) {
1767 		if (id->tried++)
1768 			return (0);
1769 		/* move key to the end of the queue */
1770 		TAILQ_REMOVE(&authctxt->keys, id, next);
1771 		TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1772 		/*
1773 		 * send a test message if we have the public key. for
1774 		 * encrypted keys we cannot do this and have to load the
1775 		 * private key instead
1776 		 */
1777 		if (id->key != NULL) {
1778 			if (try_identity(id)) {
1779 				ident = format_identity(id);
1780 				debug("Offering public key: %s", ident);
1781 				free(ident);
1782 				sent = send_pubkey_test(ssh, id);
1783 			}
1784 		} else {
1785 			debug("Trying private key: %s", id->filename);
1786 			id->key = load_identity_file(id);
1787 			if (id->key != NULL) {
1788 				if (try_identity(id)) {
1789 					id->isprivate = 1;
1790 					sent = sign_and_send_pubkey(ssh, id);
1791 				}
1792 				sshkey_free(id->key);
1793 				id->key = NULL;
1794 				id->isprivate = 0;
1795 			}
1796 		}
1797 		if (sent)
1798 			return (sent);
1799 	}
1800 	return (0);
1801 }
1802 
1803 /*
1804  * Send userauth request message specifying keyboard-interactive method.
1805  */
1806 static int
userauth_kbdint(struct ssh * ssh)1807 userauth_kbdint(struct ssh *ssh)
1808 {
1809 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1810 	int r;
1811 
1812 	if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts)
1813 		return 0;
1814 	/* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1815 	if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) {
1816 		debug3("userauth_kbdint: disable: no info_req_seen");
1817 		ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1818 		return 0;
1819 	}
1820 
1821 	debug2("userauth_kbdint");
1822 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1823 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1824 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1825 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1826 	    (r = sshpkt_put_cstring(ssh, "")) != 0 ||		/* lang */
1827 	    (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ?
1828 	    options.kbd_interactive_devices : "")) != 0 ||
1829 	    (r = sshpkt_send(ssh)) != 0)
1830 		fatal("%s: %s", __func__, ssh_err(r));
1831 
1832 	ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1833 	return 1;
1834 }
1835 
1836 /*
1837  * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1838  */
1839 static int
input_userauth_info_req(int type,u_int32_t seq,struct ssh * ssh)1840 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh)
1841 {
1842 	Authctxt *authctxt = ssh->authctxt;
1843 	char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL;
1844 	char *response = NULL;
1845 	u_char echo = 0;
1846 	u_int num_prompts, i;
1847 	int r;
1848 
1849 	debug2("input_userauth_info_req");
1850 
1851 	if (authctxt == NULL)
1852 		fatal("input_userauth_info_req: no authentication context");
1853 
1854 	authctxt->info_req_seen = 1;
1855 
1856 	if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 ||
1857 	    (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 ||
1858 	    (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
1859 		goto out;
1860 	if (strlen(name) > 0)
1861 		logit("%s", name);
1862 	if (strlen(inst) > 0)
1863 		logit("%s", inst);
1864 
1865 	if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0)
1866 		goto out;
1867 	/*
1868 	 * Begin to build info response packet based on prompts requested.
1869 	 * We commit to providing the correct number of responses, so if
1870 	 * further on we run into a problem that prevents this, we have to
1871 	 * be sure and clean this up and send a correct error response.
1872 	 */
1873 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 ||
1874 	    (r = sshpkt_put_u32(ssh, num_prompts)) != 0)
1875 		goto out;
1876 
1877 	debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1878 	for (i = 0; i < num_prompts; i++) {
1879 		if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 ||
1880 		    (r = sshpkt_get_u8(ssh, &echo)) != 0)
1881 			goto out;
1882 		response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1883 		if ((r = sshpkt_put_cstring(ssh, response)) != 0)
1884 			goto out;
1885 		freezero(response, strlen(response));
1886 		free(prompt);
1887 		response = prompt = NULL;
1888 	}
1889 	/* done with parsing incoming message. */
1890 	if ((r = sshpkt_get_end(ssh)) != 0 ||
1891 	    (r = sshpkt_add_padding(ssh, 64)) != 0)
1892 		goto out;
1893 	r = sshpkt_send(ssh);
1894  out:
1895 	if (response)
1896 		freezero(response, strlen(response));
1897 	free(prompt);
1898 	free(name);
1899 	free(inst);
1900 	free(lang);
1901 	return r;
1902 }
1903 
1904 static int
ssh_keysign(struct ssh * ssh,struct sshkey * key,u_char ** sigp,size_t * lenp,const u_char * data,size_t datalen)1905 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
1906     const u_char *data, size_t datalen)
1907 {
1908 	struct sshbuf *b;
1909 	struct stat st;
1910 	pid_t pid;
1911 	int r, to[2], from[2], status;
1912 	int sock = ssh_packet_get_connection_in(ssh);
1913 	u_char rversion = 0, version = 2;
1914 	void (*osigchld)(int);
1915 
1916 	*sigp = NULL;
1917 	*lenp = 0;
1918 
1919 	if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) {
1920 		error("%s: not installed: %s", __func__, strerror(errno));
1921 		return -1;
1922 	}
1923 	if (fflush(stdout) != 0) {
1924 		error("%s: fflush: %s", __func__, strerror(errno));
1925 		return -1;
1926 	}
1927 	if (pipe(to) == -1) {
1928 		error("%s: pipe: %s", __func__, strerror(errno));
1929 		return -1;
1930 	}
1931 	if (pipe(from) == -1) {
1932 		error("%s: pipe: %s", __func__, strerror(errno));
1933 		return -1;
1934 	}
1935 	if ((pid = fork()) == -1) {
1936 		error("%s: fork: %s", __func__, strerror(errno));
1937 		return -1;
1938 	}
1939 	osigchld = ssh_signal(SIGCHLD, SIG_DFL);
1940 	if (pid == 0) {
1941 		close(from[0]);
1942 		if (dup2(from[1], STDOUT_FILENO) == -1)
1943 			fatal("%s: dup2: %s", __func__, strerror(errno));
1944 		close(to[1]);
1945 		if (dup2(to[0], STDIN_FILENO) == -1)
1946 			fatal("%s: dup2: %s", __func__, strerror(errno));
1947 		close(from[1]);
1948 		close(to[0]);
1949 
1950 		if (dup2(sock, STDERR_FILENO + 1) == -1)
1951 			fatal("%s: dup2: %s", __func__, strerror(errno));
1952 		sock = STDERR_FILENO + 1;
1953 		fcntl(sock, F_SETFD, 0);	/* keep the socket on exec */
1954 		closefrom(sock + 1);
1955 
1956 		debug3("%s: [child] pid=%ld, exec %s",
1957 		    __func__, (long)getpid(), _PATH_SSH_KEY_SIGN);
1958 		execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL);
1959 		fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN,
1960 		    strerror(errno));
1961 	}
1962 	close(from[1]);
1963 	close(to[0]);
1964 	sock = STDERR_FILENO + 1;
1965 
1966 	if ((b = sshbuf_new()) == NULL)
1967 		fatal("%s: sshbuf_new failed", __func__);
1968 	/* send # of sock, data to be signed */
1969 	if ((r = sshbuf_put_u32(b, sock)) != 0 ||
1970 	    (r = sshbuf_put_string(b, data, datalen)) != 0)
1971 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
1972 	if (ssh_msg_send(to[1], version, b) == -1)
1973 		fatal("%s: couldn't send request", __func__);
1974 	sshbuf_reset(b);
1975 	r = ssh_msg_recv(from[0], b);
1976 	close(from[0]);
1977 	close(to[1]);
1978 	if (r < 0) {
1979 		error("%s: no reply", __func__);
1980 		goto fail;
1981 	}
1982 
1983 	errno = 0;
1984 	while (waitpid(pid, &status, 0) == -1) {
1985 		if (errno != EINTR) {
1986 			error("%s: waitpid %ld: %s",
1987 			    __func__, (long)pid, strerror(errno));
1988 			goto fail;
1989 		}
1990 	}
1991 	if (!WIFEXITED(status)) {
1992 		error("%s: exited abnormally", __func__);
1993 		goto fail;
1994 	}
1995 	if (WEXITSTATUS(status) != 0) {
1996 		error("%s: exited with status %d",
1997 		    __func__, WEXITSTATUS(status));
1998 		goto fail;
1999 	}
2000 	if ((r = sshbuf_get_u8(b, &rversion)) != 0) {
2001 		error("%s: buffer error: %s", __func__, ssh_err(r));
2002 		goto fail;
2003 	}
2004 	if (rversion != version) {
2005 		error("%s: bad version", __func__);
2006 		goto fail;
2007 	}
2008 	if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) {
2009 		error("%s: buffer error: %s", __func__, ssh_err(r));
2010  fail:
2011 		ssh_signal(SIGCHLD, osigchld);
2012 		sshbuf_free(b);
2013 		return -1;
2014 	}
2015 	ssh_signal(SIGCHLD, osigchld);
2016 	sshbuf_free(b);
2017 
2018 	return 0;
2019 }
2020 
2021 static int
userauth_hostbased(struct ssh * ssh)2022 userauth_hostbased(struct ssh *ssh)
2023 {
2024 	Authctxt *authctxt = (Authctxt *)ssh->authctxt;
2025 	struct sshkey *private = NULL;
2026 	struct sshbuf *b = NULL;
2027 	u_char *sig = NULL, *keyblob = NULL;
2028 	char *fp = NULL, *chost = NULL, *lname = NULL;
2029 	size_t siglen = 0, keylen = 0;
2030 	int i, r, success = 0;
2031 
2032 	if (authctxt->ktypes == NULL) {
2033 		authctxt->oktypes = xstrdup(options.hostbased_key_types);
2034 		authctxt->ktypes = authctxt->oktypes;
2035 	}
2036 
2037 	/*
2038 	 * Work through each listed type pattern in HostbasedKeyTypes,
2039 	 * trying each hostkey that matches the type in turn.
2040 	 */
2041 	for (;;) {
2042 		if (authctxt->active_ktype == NULL)
2043 			authctxt->active_ktype = strsep(&authctxt->ktypes, ",");
2044 		if (authctxt->active_ktype == NULL ||
2045 		    *authctxt->active_ktype == '\0')
2046 			break;
2047 		debug3("%s: trying key type %s", __func__,
2048 		    authctxt->active_ktype);
2049 
2050 		/* check for a useful key */
2051 		private = NULL;
2052 		for (i = 0; i < authctxt->sensitive->nkeys; i++) {
2053 			if (authctxt->sensitive->keys[i] == NULL ||
2054 			    authctxt->sensitive->keys[i]->type == KEY_UNSPEC)
2055 				continue;
2056 			if (match_pattern_list(
2057 			    sshkey_ssh_name(authctxt->sensitive->keys[i]),
2058 			    authctxt->active_ktype, 0) != 1)
2059 				continue;
2060 			/* we take and free the key */
2061 			private = authctxt->sensitive->keys[i];
2062 			authctxt->sensitive->keys[i] = NULL;
2063 			break;
2064 		}
2065 		/* Found one */
2066 		if (private != NULL)
2067 			break;
2068 		/* No more keys of this type; advance */
2069 		authctxt->active_ktype = NULL;
2070 	}
2071 	if (private == NULL) {
2072 		free(authctxt->oktypes);
2073 		authctxt->oktypes = authctxt->ktypes = NULL;
2074 		authctxt->active_ktype = NULL;
2075 		debug("No more client hostkeys for hostbased authentication.");
2076 		goto out;
2077 	}
2078 
2079 	if ((fp = sshkey_fingerprint(private, options.fingerprint_hash,
2080 	    SSH_FP_DEFAULT)) == NULL) {
2081 		error("%s: sshkey_fingerprint failed", __func__);
2082 		goto out;
2083 	}
2084 	debug("%s: trying hostkey %s %s",
2085 	    __func__, sshkey_ssh_name(private), fp);
2086 
2087 	/* figure out a name for the client host */
2088 	lname = get_local_name(ssh_packet_get_connection_in(ssh));
2089 	if (lname == NULL) {
2090 		error("%s: cannot get local ipaddr/name", __func__);
2091 		goto out;
2092 	}
2093 
2094 	/* XXX sshbuf_put_stringf? */
2095 	xasprintf(&chost, "%s.", lname);
2096 	debug2("%s: chost %s", __func__, chost);
2097 
2098 	/* construct data */
2099 	if ((b = sshbuf_new()) == NULL) {
2100 		error("%s: sshbuf_new failed", __func__);
2101 		goto out;
2102 	}
2103 	if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) {
2104 		error("%s: sshkey_to_blob: %s", __func__, ssh_err(r));
2105 		goto out;
2106 	}
2107 	if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 ||
2108 	    (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
2109 	    (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
2110 	    (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
2111 	    (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
2112 	    (r = sshbuf_put_cstring(b, sshkey_ssh_name(private))) != 0 ||
2113 	    (r = sshbuf_put_string(b, keyblob, keylen)) != 0 ||
2114 	    (r = sshbuf_put_cstring(b, chost)) != 0 ||
2115 	    (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) {
2116 		error("%s: buffer error: %s", __func__, ssh_err(r));
2117 		goto out;
2118 	}
2119 
2120 #ifdef DEBUG_PK
2121 	sshbuf_dump(b, stderr);
2122 #endif
2123 	if ((r = ssh_keysign(ssh, private, &sig, &siglen,
2124 	    sshbuf_ptr(b), sshbuf_len(b))) != 0) {
2125 		error("sign using hostkey %s %s failed",
2126 		    sshkey_ssh_name(private), fp);
2127 		goto out;
2128 	}
2129 	if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
2130 	    (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
2131 	    (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
2132 	    (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
2133 	    (r = sshpkt_put_cstring(ssh, sshkey_ssh_name(private))) != 0 ||
2134 	    (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 ||
2135 	    (r = sshpkt_put_cstring(ssh, chost)) != 0 ||
2136 	    (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 ||
2137 	    (r = sshpkt_put_string(ssh, sig, siglen)) != 0 ||
2138 	    (r = sshpkt_send(ssh)) != 0) {
2139 		error("%s: packet error: %s", __func__, ssh_err(r));
2140 		goto out;
2141 	}
2142 	success = 1;
2143 
2144  out:
2145 	if (sig != NULL)
2146 		freezero(sig, siglen);
2147 	free(keyblob);
2148 	free(lname);
2149 	free(fp);
2150 	free(chost);
2151 	sshkey_free(private);
2152 	sshbuf_free(b);
2153 
2154 	return success;
2155 }
2156 
2157 /* find auth method */
2158 
2159 /*
2160  * given auth method name, if configurable options permit this method fill
2161  * in auth_ident field and return true, otherwise return false.
2162  */
2163 static int
authmethod_is_enabled(Authmethod * method)2164 authmethod_is_enabled(Authmethod *method)
2165 {
2166 	if (method == NULL)
2167 		return 0;
2168 	/* return false if options indicate this method is disabled */
2169 	if  (method->enabled == NULL || *method->enabled == 0)
2170 		return 0;
2171 	/* return false if batch mode is enabled but method needs interactive mode */
2172 	if  (method->batch_flag != NULL && *method->batch_flag != 0)
2173 		return 0;
2174 	return 1;
2175 }
2176 
2177 static Authmethod *
authmethod_lookup(const char * name)2178 authmethod_lookup(const char *name)
2179 {
2180 	Authmethod *method = NULL;
2181 	if (name != NULL)
2182 		for (method = authmethods; method->name != NULL; method++)
2183 			if (strcmp(name, method->name) == 0)
2184 				return method;
2185 	debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
2186 	return NULL;
2187 }
2188 
2189 /* XXX internal state */
2190 static Authmethod *current = NULL;
2191 static char *supported = NULL;
2192 static char *preferred = NULL;
2193 
2194 /*
2195  * Given the authentication method list sent by the server, return the
2196  * next method we should try.  If the server initially sends a nil list,
2197  * use a built-in default list.
2198  */
2199 static Authmethod *
authmethod_get(char * authlist)2200 authmethod_get(char *authlist)
2201 {
2202 	char *name = NULL;
2203 	u_int next;
2204 
2205 	/* Use a suitable default if we're passed a nil list.  */
2206 	if (authlist == NULL || strlen(authlist) == 0)
2207 		authlist = options.preferred_authentications;
2208 
2209 	if (supported == NULL || strcmp(authlist, supported) != 0) {
2210 		debug3("start over, passed a different list %s", authlist);
2211 		free(supported);
2212 		supported = xstrdup(authlist);
2213 		preferred = options.preferred_authentications;
2214 		debug3("preferred %s", preferred);
2215 		current = NULL;
2216 	} else if (current != NULL && authmethod_is_enabled(current))
2217 		return current;
2218 
2219 	for (;;) {
2220 		if ((name = match_list(preferred, supported, &next)) == NULL) {
2221 			debug("No more authentication methods to try.");
2222 			current = NULL;
2223 			return NULL;
2224 		}
2225 		preferred += next;
2226 		debug3("authmethod_lookup %s", name);
2227 		debug3("remaining preferred: %s", preferred);
2228 		if ((current = authmethod_lookup(name)) != NULL &&
2229 		    authmethod_is_enabled(current)) {
2230 			debug3("authmethod_is_enabled %s", name);
2231 			debug("Next authentication method: %s", name);
2232 			free(name);
2233 			return current;
2234 		}
2235 		free(name);
2236 	}
2237 }
2238 
2239 static char *
authmethods_get(void)2240 authmethods_get(void)
2241 {
2242 	Authmethod *method = NULL;
2243 	struct sshbuf *b;
2244 	char *list;
2245 	int r;
2246 
2247 	if ((b = sshbuf_new()) == NULL)
2248 		fatal("%s: sshbuf_new failed", __func__);
2249 	for (method = authmethods; method->name != NULL; method++) {
2250 		if (authmethod_is_enabled(method)) {
2251 			if ((r = sshbuf_putf(b, "%s%s",
2252 			    sshbuf_len(b) ? "," : "", method->name)) != 0)
2253 				fatal("%s: buffer error: %s",
2254 				    __func__, ssh_err(r));
2255 		}
2256 	}
2257 	if ((list = sshbuf_dup_string(b)) == NULL)
2258 		fatal("%s: sshbuf_dup_string failed", __func__);
2259 	sshbuf_free(b);
2260 	return list;
2261 }
2262