1 /* $OpenBSD: sshconnect2.c,v 1.255 2017/03/11 23:40:26 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 <stdarg.h>
40 #include <stdio.h>
41 #include <string.h>
42 #include <unistd.h>
43 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
44 #include <vis.h>
45 #endif
46
47 #include "openbsd-compat/sys-queue.h"
48
49 #include "xmalloc.h"
50 #include "ssh.h"
51 #include "ssh2.h"
52 #include "buffer.h"
53 #include "packet.h"
54 #include "compat.h"
55 #include "cipher.h"
56 #include "key.h"
57 #include "kex.h"
58 #include "myproposal.h"
59 #include "sshconnect.h"
60 #include "authfile.h"
61 #include "dh.h"
62 #include "authfd.h"
63 #include "log.h"
64 #include "misc.h"
65 #include "readconf.h"
66 #include "match.h"
67 #include "dispatch.h"
68 #include "canohost.h"
69 #include "msg.h"
70 #include "pathnames.h"
71 #include "uidswap.h"
72 #include "hostfile.h"
73 #include "ssherr.h"
74 #include "utf8.h"
75
76 #ifdef GSSAPI
77 #include "ssh-gss.h"
78 #endif
79
80 /* import */
81 extern char *client_version_string;
82 extern char *server_version_string;
83 extern Options options;
84
85 /*
86 * SSH2 key exchange
87 */
88
89 u_char *session_id2 = NULL;
90 u_int session_id2_len = 0;
91
92 char *xxx_host;
93 struct sockaddr *xxx_hostaddr;
94
95 static int
verify_host_key_callback(Key * hostkey,struct ssh * ssh)96 verify_host_key_callback(Key *hostkey, struct ssh *ssh)
97 {
98 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
99 fatal("Host key verification failed.");
100 return 0;
101 }
102
103 static char *
order_hostkeyalgs(char * host,struct sockaddr * hostaddr,u_short port)104 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
105 {
106 char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
107 size_t maxlen;
108 struct hostkeys *hostkeys;
109 int ktype;
110 u_int i;
111
112 /* Find all hostkeys for this hostname */
113 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
114 hostkeys = init_hostkeys();
115 for (i = 0; i < options.num_user_hostfiles; i++)
116 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
117 for (i = 0; i < options.num_system_hostfiles; i++)
118 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
119
120 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
121 maxlen = strlen(avail) + 1;
122 first = xmalloc(maxlen);
123 last = xmalloc(maxlen);
124 *first = *last = '\0';
125
126 #define ALG_APPEND(to, from) \
127 do { \
128 if (*to != '\0') \
129 strlcat(to, ",", maxlen); \
130 strlcat(to, from, maxlen); \
131 } while (0)
132
133 while ((alg = strsep(&avail, ",")) && *alg != '\0') {
134 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
135 fatal("%s: unknown alg %s", __func__, alg);
136 if (lookup_key_in_hostkeys_by_type(hostkeys,
137 sshkey_type_plain(ktype), NULL))
138 ALG_APPEND(first, alg);
139 else
140 ALG_APPEND(last, alg);
141 }
142 #undef ALG_APPEND
143 xasprintf(&ret, "%s%s%s", first,
144 (*first == '\0' || *last == '\0') ? "" : ",", last);
145 if (*first != '\0')
146 debug3("%s: prefer hostkeyalgs: %s", __func__, first);
147
148 free(first);
149 free(last);
150 free(hostname);
151 free(oavail);
152 free_hostkeys(hostkeys);
153
154 return ret;
155 }
156
157 void
ssh_kex2(char * host,struct sockaddr * hostaddr,u_short port)158 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
159 {
160 char *myproposal[PROPOSAL_MAX] = { KEX_CLIENT };
161 char *s;
162 struct kex *kex;
163 int r;
164
165 xxx_host = host;
166 xxx_hostaddr = hostaddr;
167
168 if ((s = kex_names_cat(options.kex_algorithms, "ext-info-c")) == NULL)
169 fatal("%s: kex_names_cat", __func__);
170 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(s);
171 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
172 compat_cipher_proposal(options.ciphers);
173 myproposal[PROPOSAL_ENC_ALGS_STOC] =
174 compat_cipher_proposal(options.ciphers);
175 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
176 myproposal[PROPOSAL_COMP_ALGS_STOC] = options.compression ?
177 "zlib@openssh.com,zlib,none" : "none,zlib@openssh.com,zlib";
178 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
179 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
180 if (options.hostkeyalgorithms != NULL) {
181 if (kex_assemble_names(KEX_DEFAULT_PK_ALG,
182 &options.hostkeyalgorithms) != 0)
183 fatal("%s: kex_assemble_namelist", __func__);
184 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
185 compat_pkalg_proposal(options.hostkeyalgorithms);
186 } else {
187 /* Enforce default */
188 options.hostkeyalgorithms = xstrdup(KEX_DEFAULT_PK_ALG);
189 /* Prefer algorithms that we already have keys for */
190 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
191 compat_pkalg_proposal(
192 order_hostkeyalgs(host, hostaddr, port));
193 }
194
195 if (options.rekey_limit || options.rekey_interval)
196 packet_set_rekey_limits(options.rekey_limit,
197 options.rekey_interval);
198
199 /* start key exchange */
200 if ((r = kex_setup(active_state, myproposal)) != 0)
201 fatal("kex_setup: %s", ssh_err(r));
202 kex = active_state->kex;
203 #ifdef WITH_OPENSSL
204 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
205 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
206 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_client;
207 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_client;
208 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_client;
209 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
210 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
211 # ifdef OPENSSL_HAS_ECC
212 kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
213 # endif
214 #endif
215 kex->kex[KEX_C25519_SHA256] = kexc25519_client;
216 kex->client_version_string=client_version_string;
217 kex->server_version_string=server_version_string;
218 kex->verify_host_key=&verify_host_key_callback;
219
220 dispatch_run(DISPATCH_BLOCK, &kex->done, active_state);
221
222 /* remove ext-info from the KEX proposals for rekeying */
223 myproposal[PROPOSAL_KEX_ALGS] =
224 compat_kex_proposal(options.kex_algorithms);
225 if ((r = kex_prop2buf(kex->my, myproposal)) != 0)
226 fatal("kex_prop2buf: %s", ssh_err(r));
227
228 session_id2 = kex->session_id;
229 session_id2_len = kex->session_id_len;
230
231 #ifdef DEBUG_KEXDH
232 /* send 1st encrypted/maced/compressed message */
233 packet_start(SSH2_MSG_IGNORE);
234 packet_put_cstring("markus");
235 packet_send();
236 packet_write_wait();
237 #endif
238 }
239
240 /*
241 * Authenticate user
242 */
243
244 typedef struct cauthctxt Authctxt;
245 typedef struct cauthmethod Authmethod;
246 typedef struct identity Identity;
247 typedef struct idlist Idlist;
248
249 struct identity {
250 TAILQ_ENTRY(identity) next;
251 int agent_fd; /* >=0 if agent supports key */
252 struct sshkey *key; /* public/private key */
253 char *filename; /* comment for agent-only keys */
254 int tried;
255 int isprivate; /* key points to the private key */
256 int userprovided;
257 };
258 TAILQ_HEAD(idlist, identity);
259
260 struct cauthctxt {
261 const char *server_user;
262 const char *local_user;
263 const char *host;
264 const char *service;
265 struct cauthmethod *method;
266 sig_atomic_t success;
267 char *authlist;
268 int attempt;
269 /* pubkey */
270 struct idlist keys;
271 int agent_fd;
272 /* hostbased */
273 Sensitive *sensitive;
274 char *oktypes, *ktypes;
275 const char *active_ktype;
276 /* kbd-interactive */
277 int info_req_seen;
278 /* generic */
279 void *methoddata;
280 };
281
282 struct cauthmethod {
283 char *name; /* string to compare against server's list */
284 int (*userauth)(Authctxt *authctxt);
285 void (*cleanup)(Authctxt *authctxt);
286 int *enabled; /* flag in option struct that enables method */
287 int *batch_flag; /* flag in option struct that disables method */
288 };
289
290 int input_userauth_service_accept(int, u_int32_t, void *);
291 int input_userauth_ext_info(int, u_int32_t, void *);
292 int input_userauth_success(int, u_int32_t, void *);
293 int input_userauth_success_unexpected(int, u_int32_t, void *);
294 int input_userauth_failure(int, u_int32_t, void *);
295 int input_userauth_banner(int, u_int32_t, void *);
296 int input_userauth_error(int, u_int32_t, void *);
297 int input_userauth_info_req(int, u_int32_t, void *);
298 int input_userauth_pk_ok(int, u_int32_t, void *);
299 int input_userauth_passwd_changereq(int, u_int32_t, void *);
300
301 int userauth_none(Authctxt *);
302 int userauth_pubkey(Authctxt *);
303 int userauth_passwd(Authctxt *);
304 int userauth_kbdint(Authctxt *);
305 int userauth_hostbased(Authctxt *);
306
307 #ifdef GSSAPI
308 int userauth_gssapi(Authctxt *authctxt);
309 int input_gssapi_response(int type, u_int32_t, void *);
310 int input_gssapi_token(int type, u_int32_t, void *);
311 int input_gssapi_hash(int type, u_int32_t, void *);
312 int input_gssapi_error(int, u_int32_t, void *);
313 int input_gssapi_errtok(int, u_int32_t, void *);
314 #endif
315
316 void userauth(Authctxt *, char *);
317
318 static int sign_and_send_pubkey(Authctxt *, Identity *);
319 static void pubkey_prepare(Authctxt *);
320 static void pubkey_cleanup(Authctxt *);
321 static void pubkey_reset(Authctxt *);
322 static Key *load_identity_file(Identity *);
323
324 static Authmethod *authmethod_get(char *authlist);
325 static Authmethod *authmethod_lookup(const char *name);
326 static char *authmethods_get(void);
327
328 Authmethod authmethods[] = {
329 #ifdef GSSAPI
330 {"gssapi-with-mic",
331 userauth_gssapi,
332 NULL,
333 &options.gss_authentication,
334 NULL},
335 #endif
336 {"hostbased",
337 userauth_hostbased,
338 NULL,
339 &options.hostbased_authentication,
340 NULL},
341 {"publickey",
342 userauth_pubkey,
343 NULL,
344 &options.pubkey_authentication,
345 NULL},
346 {"keyboard-interactive",
347 userauth_kbdint,
348 NULL,
349 &options.kbd_interactive_authentication,
350 &options.batch_mode},
351 {"password",
352 userauth_passwd,
353 NULL,
354 &options.password_authentication,
355 &options.batch_mode},
356 {"none",
357 userauth_none,
358 NULL,
359 NULL,
360 NULL},
361 {NULL, NULL, NULL, NULL, NULL}
362 };
363
364 void
ssh_userauth2(const char * local_user,const char * server_user,char * host,Sensitive * sensitive)365 ssh_userauth2(const char *local_user, const char *server_user, char *host,
366 Sensitive *sensitive)
367 {
368 struct ssh *ssh = active_state;
369 Authctxt authctxt;
370 int r;
371
372 if (options.challenge_response_authentication)
373 options.kbd_interactive_authentication = 1;
374 if (options.preferred_authentications == NULL)
375 options.preferred_authentications = authmethods_get();
376
377 /* setup authentication context */
378 memset(&authctxt, 0, sizeof(authctxt));
379 pubkey_prepare(&authctxt);
380 authctxt.server_user = server_user;
381 authctxt.local_user = local_user;
382 authctxt.host = host;
383 authctxt.service = "ssh-connection"; /* service name */
384 authctxt.success = 0;
385 authctxt.method = authmethod_lookup("none");
386 authctxt.authlist = NULL;
387 authctxt.methoddata = NULL;
388 authctxt.sensitive = sensitive;
389 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL;
390 authctxt.info_req_seen = 0;
391 authctxt.agent_fd = -1;
392 if (authctxt.method == NULL)
393 fatal("ssh_userauth2: internal error: cannot send userauth none request");
394
395 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 ||
396 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 ||
397 (r = sshpkt_send(ssh)) != 0)
398 fatal("%s: %s", __func__, ssh_err(r));
399
400 ssh_dispatch_init(ssh, &input_userauth_error);
401 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_ext_info);
402 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept);
403 ssh_dispatch_run(ssh, DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */
404
405 pubkey_cleanup(&authctxt);
406 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
407
408 if (!authctxt.success)
409 fatal("Authentication failed.");
410 debug("Authentication succeeded (%s).", authctxt.method->name);
411 }
412
413 /* ARGSUSED */
414 int
input_userauth_service_accept(int type,u_int32_t seqnr,void * ctxt)415 input_userauth_service_accept(int type, u_int32_t seqnr, void *ctxt)
416 {
417 Authctxt *authctxt = ctxt;
418 struct ssh *ssh = active_state;
419 int r;
420
421 if (ssh_packet_remaining(ssh) > 0) {
422 char *reply;
423
424 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0)
425 goto out;
426 debug2("service_accept: %s", reply);
427 free(reply);
428 } else {
429 debug2("buggy server: service_accept w/o service");
430 }
431 if ((r = sshpkt_get_end(ssh)) != 0)
432 goto out;
433 debug("SSH2_MSG_SERVICE_ACCEPT received");
434
435 /* initial userauth request */
436 userauth_none(authctxt);
437
438 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, &input_userauth_error);
439 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
440 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
441 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
442 r = 0;
443 out:
444 return r;
445 }
446
447 /* ARGSUSED */
448 int
input_userauth_ext_info(int type,u_int32_t seqnr,void * ctxt)449 input_userauth_ext_info(int type, u_int32_t seqnr, void *ctxt)
450 {
451 return kex_input_ext_info(type, seqnr, active_state);
452 }
453
454 void
userauth(Authctxt * authctxt,char * authlist)455 userauth(Authctxt *authctxt, char *authlist)
456 {
457 if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
458 authctxt->method->cleanup(authctxt);
459
460 free(authctxt->methoddata);
461 authctxt->methoddata = NULL;
462 if (authlist == NULL) {
463 authlist = authctxt->authlist;
464 } else {
465 free(authctxt->authlist);
466 authctxt->authlist = authlist;
467 }
468 for (;;) {
469 Authmethod *method = authmethod_get(authlist);
470 if (method == NULL)
471 fatal("Permission denied (%s).", authlist);
472 authctxt->method = method;
473
474 /* reset the per method handler */
475 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
476 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
477
478 /* and try new method */
479 if (method->userauth(authctxt) != 0) {
480 debug2("we sent a %s packet, wait for reply", method->name);
481 break;
482 } else {
483 debug2("we did not send a packet, disable method");
484 method->enabled = NULL;
485 }
486 }
487 }
488
489 /* ARGSUSED */
490 int
input_userauth_error(int type,u_int32_t seq,void * ctxt)491 input_userauth_error(int type, u_int32_t seq, void *ctxt)
492 {
493 fatal("input_userauth_error: bad message during authentication: "
494 "type %d", type);
495 return 0;
496 }
497
498 /* ARGSUSED */
499 int
input_userauth_banner(int type,u_int32_t seq,void * ctxt)500 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
501 {
502 char *msg, *lang;
503 u_int len;
504
505 debug3("%s", __func__);
506 msg = packet_get_string(&len);
507 lang = packet_get_string(NULL);
508 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO)
509 fmprintf(stderr, "%s", msg);
510 free(msg);
511 free(lang);
512 return 0;
513 }
514
515 /* ARGSUSED */
516 int
input_userauth_success(int type,u_int32_t seq,void * ctxt)517 input_userauth_success(int type, u_int32_t seq, void *ctxt)
518 {
519 Authctxt *authctxt = ctxt;
520
521 if (authctxt == NULL)
522 fatal("input_userauth_success: no authentication context");
523 free(authctxt->authlist);
524 authctxt->authlist = NULL;
525 if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
526 authctxt->method->cleanup(authctxt);
527 free(authctxt->methoddata);
528 authctxt->methoddata = NULL;
529 authctxt->success = 1; /* break out */
530 return 0;
531 }
532
533 int
input_userauth_success_unexpected(int type,u_int32_t seq,void * ctxt)534 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
535 {
536 Authctxt *authctxt = ctxt;
537
538 if (authctxt == NULL)
539 fatal("%s: no authentication context", __func__);
540
541 fatal("Unexpected authentication success during %s.",
542 authctxt->method->name);
543 return 0;
544 }
545
546 /* ARGSUSED */
547 int
input_userauth_failure(int type,u_int32_t seq,void * ctxt)548 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
549 {
550 Authctxt *authctxt = ctxt;
551 char *authlist = NULL;
552 int partial;
553
554 if (authctxt == NULL)
555 fatal("input_userauth_failure: no authentication context");
556
557 authlist = packet_get_string(NULL);
558 partial = packet_get_char();
559 packet_check_eom();
560
561 if (partial != 0) {
562 verbose("Authenticated with partial success.");
563 /* reset state */
564 pubkey_reset(authctxt);
565 }
566 debug("Authentications that can continue: %s", authlist);
567
568 userauth(authctxt, authlist);
569 return 0;
570 }
571
572 /* ARGSUSED */
573 int
input_userauth_pk_ok(int type,u_int32_t seq,void * ctxt)574 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
575 {
576 Authctxt *authctxt = ctxt;
577 Key *key = NULL;
578 Identity *id = NULL;
579 Buffer b;
580 int pktype, sent = 0;
581 u_int alen, blen;
582 char *pkalg, *fp;
583 u_char *pkblob;
584
585 if (authctxt == NULL)
586 fatal("input_userauth_pk_ok: no authentication context");
587 if (datafellows & SSH_BUG_PKOK) {
588 /* this is similar to SSH_BUG_PKAUTH */
589 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
590 pkblob = packet_get_string(&blen);
591 buffer_init(&b);
592 buffer_append(&b, pkblob, blen);
593 pkalg = buffer_get_string(&b, &alen);
594 buffer_free(&b);
595 } else {
596 pkalg = packet_get_string(&alen);
597 pkblob = packet_get_string(&blen);
598 }
599 packet_check_eom();
600
601 debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
602
603 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
604 debug("unknown pkalg %s", pkalg);
605 goto done;
606 }
607 if ((key = key_from_blob(pkblob, blen)) == NULL) {
608 debug("no key from blob. pkalg %s", pkalg);
609 goto done;
610 }
611 if (key->type != pktype) {
612 error("input_userauth_pk_ok: type mismatch "
613 "for decoded key (received %d, expected %d)",
614 key->type, pktype);
615 goto done;
616 }
617 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
618 SSH_FP_DEFAULT)) == NULL)
619 goto done;
620 debug2("input_userauth_pk_ok: fp %s", fp);
621 free(fp);
622
623 /*
624 * search keys in the reverse order, because last candidate has been
625 * moved to the end of the queue. this also avoids confusion by
626 * duplicate keys
627 */
628 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
629 if (key_equal(key, id->key)) {
630 sent = sign_and_send_pubkey(authctxt, id);
631 break;
632 }
633 }
634 done:
635 if (key != NULL)
636 key_free(key);
637 free(pkalg);
638 free(pkblob);
639
640 /* try another method if we did not send a packet */
641 if (sent == 0)
642 userauth(authctxt, NULL);
643 return 0;
644 }
645
646 #ifdef GSSAPI
647 int
userauth_gssapi(Authctxt * authctxt)648 userauth_gssapi(Authctxt *authctxt)
649 {
650 Gssctxt *gssctxt = NULL;
651 static gss_OID_set gss_supported = NULL;
652 static u_int mech = 0;
653 OM_uint32 min;
654 int ok = 0;
655
656 /* Try one GSSAPI method at a time, rather than sending them all at
657 * once. */
658
659 if (gss_supported == NULL)
660 gss_indicate_mechs(&min, &gss_supported);
661
662 /* Check to see if the mechanism is usable before we offer it */
663 while (mech < gss_supported->count && !ok) {
664 /* My DER encoding requires length<128 */
665 if (gss_supported->elements[mech].length < 128 &&
666 ssh_gssapi_check_mechanism(&gssctxt,
667 &gss_supported->elements[mech], authctxt->host)) {
668 ok = 1; /* Mechanism works */
669 } else {
670 mech++;
671 }
672 }
673
674 if (!ok)
675 return 0;
676
677 authctxt->methoddata=(void *)gssctxt;
678
679 packet_start(SSH2_MSG_USERAUTH_REQUEST);
680 packet_put_cstring(authctxt->server_user);
681 packet_put_cstring(authctxt->service);
682 packet_put_cstring(authctxt->method->name);
683
684 packet_put_int(1);
685
686 packet_put_int((gss_supported->elements[mech].length) + 2);
687 packet_put_char(SSH_GSS_OIDTYPE);
688 packet_put_char(gss_supported->elements[mech].length);
689 packet_put_raw(gss_supported->elements[mech].elements,
690 gss_supported->elements[mech].length);
691
692 packet_send();
693
694 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
695 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
696 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
697 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
698
699 mech++; /* Move along to next candidate */
700
701 return 1;
702 }
703
704 static OM_uint32
process_gssapi_token(void * ctxt,gss_buffer_t recv_tok)705 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
706 {
707 Authctxt *authctxt = ctxt;
708 Gssctxt *gssctxt = authctxt->methoddata;
709 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
710 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
711 gss_buffer_desc gssbuf;
712 OM_uint32 status, ms, flags;
713 Buffer b;
714
715 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
716 recv_tok, &send_tok, &flags);
717
718 if (send_tok.length > 0) {
719 if (GSS_ERROR(status))
720 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
721 else
722 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
723
724 packet_put_string(send_tok.value, send_tok.length);
725 packet_send();
726 gss_release_buffer(&ms, &send_tok);
727 }
728
729 if (status == GSS_S_COMPLETE) {
730 /* send either complete or MIC, depending on mechanism */
731 if (!(flags & GSS_C_INTEG_FLAG)) {
732 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
733 packet_send();
734 } else {
735 ssh_gssapi_buildmic(&b, authctxt->server_user,
736 authctxt->service, "gssapi-with-mic");
737
738 gssbuf.value = buffer_ptr(&b);
739 gssbuf.length = buffer_len(&b);
740
741 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
742
743 if (!GSS_ERROR(status)) {
744 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
745 packet_put_string(mic.value, mic.length);
746
747 packet_send();
748 }
749
750 buffer_free(&b);
751 gss_release_buffer(&ms, &mic);
752 }
753 }
754
755 return status;
756 }
757
758 /* ARGSUSED */
759 int
input_gssapi_response(int type,u_int32_t plen,void * ctxt)760 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
761 {
762 Authctxt *authctxt = ctxt;
763 Gssctxt *gssctxt;
764 int oidlen;
765 char *oidv;
766
767 if (authctxt == NULL)
768 fatal("input_gssapi_response: no authentication context");
769 gssctxt = authctxt->methoddata;
770
771 /* Setup our OID */
772 oidv = packet_get_string(&oidlen);
773
774 if (oidlen <= 2 ||
775 oidv[0] != SSH_GSS_OIDTYPE ||
776 oidv[1] != oidlen - 2) {
777 free(oidv);
778 debug("Badly encoded mechanism OID received");
779 userauth(authctxt, NULL);
780 return 0;
781 }
782
783 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
784 fatal("Server returned different OID than expected");
785
786 packet_check_eom();
787
788 free(oidv);
789
790 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
791 /* Start again with next method on list */
792 debug("Trying to start again");
793 userauth(authctxt, NULL);
794 return 0;
795 }
796 return 0;
797 }
798
799 /* ARGSUSED */
800 int
input_gssapi_token(int type,u_int32_t plen,void * ctxt)801 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
802 {
803 Authctxt *authctxt = ctxt;
804 gss_buffer_desc recv_tok;
805 OM_uint32 status;
806 u_int slen;
807
808 if (authctxt == NULL)
809 fatal("input_gssapi_response: no authentication context");
810
811 recv_tok.value = packet_get_string(&slen);
812 recv_tok.length = slen; /* safe typecast */
813
814 packet_check_eom();
815
816 status = process_gssapi_token(ctxt, &recv_tok);
817
818 free(recv_tok.value);
819
820 if (GSS_ERROR(status)) {
821 /* Start again with the next method in the list */
822 userauth(authctxt, NULL);
823 return 0;
824 }
825 return 0;
826 }
827
828 /* ARGSUSED */
829 int
input_gssapi_errtok(int type,u_int32_t plen,void * ctxt)830 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
831 {
832 Authctxt *authctxt = ctxt;
833 Gssctxt *gssctxt;
834 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
835 gss_buffer_desc recv_tok;
836 OM_uint32 ms;
837 u_int len;
838
839 if (authctxt == NULL)
840 fatal("input_gssapi_response: no authentication context");
841 gssctxt = authctxt->methoddata;
842
843 recv_tok.value = packet_get_string(&len);
844 recv_tok.length = len;
845
846 packet_check_eom();
847
848 /* Stick it into GSSAPI and see what it says */
849 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
850 &recv_tok, &send_tok, NULL);
851
852 free(recv_tok.value);
853 gss_release_buffer(&ms, &send_tok);
854
855 /* Server will be returning a failed packet after this one */
856 return 0;
857 }
858
859 /* ARGSUSED */
860 int
input_gssapi_error(int type,u_int32_t plen,void * ctxt)861 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
862 {
863 char *msg;
864 char *lang;
865
866 /* maj */(void)packet_get_int();
867 /* min */(void)packet_get_int();
868 msg=packet_get_string(NULL);
869 lang=packet_get_string(NULL);
870
871 packet_check_eom();
872
873 debug("Server GSSAPI Error:\n%s", msg);
874 free(msg);
875 free(lang);
876 return 0;
877 }
878 #endif /* GSSAPI */
879
880 int
userauth_none(Authctxt * authctxt)881 userauth_none(Authctxt *authctxt)
882 {
883 /* initial userauth request */
884 packet_start(SSH2_MSG_USERAUTH_REQUEST);
885 packet_put_cstring(authctxt->server_user);
886 packet_put_cstring(authctxt->service);
887 packet_put_cstring(authctxt->method->name);
888 packet_send();
889 return 1;
890 }
891
892 int
userauth_passwd(Authctxt * authctxt)893 userauth_passwd(Authctxt *authctxt)
894 {
895 static int attempt = 0;
896 char prompt[150];
897 char *password;
898 const char *host = options.host_key_alias ? options.host_key_alias :
899 authctxt->host;
900
901 if (attempt++ >= options.number_of_password_prompts)
902 return 0;
903
904 if (attempt != 1)
905 error("Permission denied, please try again.");
906
907 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
908 authctxt->server_user, host);
909 password = read_passphrase(prompt, 0);
910 packet_start(SSH2_MSG_USERAUTH_REQUEST);
911 packet_put_cstring(authctxt->server_user);
912 packet_put_cstring(authctxt->service);
913 packet_put_cstring(authctxt->method->name);
914 packet_put_char(0);
915 packet_put_cstring(password);
916 explicit_bzero(password, strlen(password));
917 free(password);
918 packet_add_padding(64);
919 packet_send();
920
921 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
922 &input_userauth_passwd_changereq);
923
924 return 1;
925 }
926
927 /*
928 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
929 */
930 /* ARGSUSED */
931 int
input_userauth_passwd_changereq(int type,u_int32_t seqnr,void * ctxt)932 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
933 {
934 Authctxt *authctxt = ctxt;
935 char *info, *lang, *password = NULL, *retype = NULL;
936 char prompt[150];
937 const char *host;
938
939 debug2("input_userauth_passwd_changereq");
940
941 if (authctxt == NULL)
942 fatal("input_userauth_passwd_changereq: "
943 "no authentication context");
944 host = options.host_key_alias ? options.host_key_alias : authctxt->host;
945
946 info = packet_get_string(NULL);
947 lang = packet_get_string(NULL);
948 if (strlen(info) > 0)
949 logit("%s", info);
950 free(info);
951 free(lang);
952 packet_start(SSH2_MSG_USERAUTH_REQUEST);
953 packet_put_cstring(authctxt->server_user);
954 packet_put_cstring(authctxt->service);
955 packet_put_cstring(authctxt->method->name);
956 packet_put_char(1); /* additional info */
957 snprintf(prompt, sizeof(prompt),
958 "Enter %.30s@%.128s's old password: ",
959 authctxt->server_user, host);
960 password = read_passphrase(prompt, 0);
961 packet_put_cstring(password);
962 explicit_bzero(password, strlen(password));
963 free(password);
964 password = NULL;
965 while (password == NULL) {
966 snprintf(prompt, sizeof(prompt),
967 "Enter %.30s@%.128s's new password: ",
968 authctxt->server_user, host);
969 password = read_passphrase(prompt, RP_ALLOW_EOF);
970 if (password == NULL) {
971 /* bail out */
972 return 0;
973 }
974 snprintf(prompt, sizeof(prompt),
975 "Retype %.30s@%.128s's new password: ",
976 authctxt->server_user, host);
977 retype = read_passphrase(prompt, 0);
978 if (strcmp(password, retype) != 0) {
979 explicit_bzero(password, strlen(password));
980 free(password);
981 logit("Mismatch; try again, EOF to quit.");
982 password = NULL;
983 }
984 explicit_bzero(retype, strlen(retype));
985 free(retype);
986 }
987 packet_put_cstring(password);
988 explicit_bzero(password, strlen(password));
989 free(password);
990 packet_add_padding(64);
991 packet_send();
992
993 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
994 &input_userauth_passwd_changereq);
995 return 0;
996 }
997
998 static const char *
key_sign_encode(const struct sshkey * key)999 key_sign_encode(const struct sshkey *key)
1000 {
1001 struct ssh *ssh = active_state;
1002
1003 if (key->type == KEY_RSA) {
1004 switch (ssh->kex->rsa_sha2) {
1005 case 256:
1006 return "rsa-sha2-256";
1007 case 512:
1008 return "rsa-sha2-512";
1009 }
1010 }
1011 return key_ssh_name(key);
1012 }
1013
1014 static int
identity_sign(struct identity * id,u_char ** sigp,size_t * lenp,const u_char * data,size_t datalen,u_int compat)1015 identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
1016 const u_char *data, size_t datalen, u_int compat)
1017 {
1018 Key *prv;
1019 int ret;
1020
1021 /* the agent supports this key */
1022 if (id->key != NULL && id->agent_fd != -1)
1023 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp,
1024 data, datalen, key_sign_encode(id->key), compat);
1025
1026 /*
1027 * we have already loaded the private key or
1028 * the private key is stored in external hardware
1029 */
1030 if (id->key != NULL &&
1031 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT)))
1032 return (sshkey_sign(id->key, sigp, lenp, data, datalen,
1033 key_sign_encode(id->key), compat));
1034
1035 /* load the private key from the file */
1036 if ((prv = load_identity_file(id)) == NULL)
1037 return SSH_ERR_KEY_NOT_FOUND;
1038 ret = sshkey_sign(prv, sigp, lenp, data, datalen,
1039 key_sign_encode(prv), compat);
1040 sshkey_free(prv);
1041 return (ret);
1042 }
1043
1044 static int
id_filename_matches(Identity * id,Identity * private_id)1045 id_filename_matches(Identity *id, Identity *private_id)
1046 {
1047 const char *suffixes[] = { ".pub", "-cert.pub", NULL };
1048 size_t len = strlen(id->filename), plen = strlen(private_id->filename);
1049 size_t i, slen;
1050
1051 if (strcmp(id->filename, private_id->filename) == 0)
1052 return 1;
1053 for (i = 0; suffixes[i]; i++) {
1054 slen = strlen(suffixes[i]);
1055 if (len > slen && plen == len - slen &&
1056 strcmp(id->filename + (len - slen), suffixes[i]) == 0 &&
1057 memcmp(id->filename, private_id->filename, plen) == 0)
1058 return 1;
1059 }
1060 return 0;
1061 }
1062
1063 static int
sign_and_send_pubkey(Authctxt * authctxt,Identity * id)1064 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1065 {
1066 Buffer b;
1067 Identity *private_id;
1068 u_char *blob, *signature;
1069 size_t slen;
1070 u_int bloblen, skip = 0;
1071 int matched, ret = -1, have_sig = 1;
1072 char *fp;
1073
1074 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
1075 SSH_FP_DEFAULT)) == NULL)
1076 return 0;
1077 debug3("%s: %s %s", __func__, key_type(id->key), fp);
1078 free(fp);
1079
1080 if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1081 /* we cannot handle this key */
1082 debug3("sign_and_send_pubkey: cannot handle key");
1083 return 0;
1084 }
1085 /* data to be signed */
1086 buffer_init(&b);
1087 if (datafellows & SSH_OLD_SESSIONID) {
1088 buffer_append(&b, session_id2, session_id2_len);
1089 skip = session_id2_len;
1090 } else {
1091 buffer_put_string(&b, session_id2, session_id2_len);
1092 skip = buffer_len(&b);
1093 }
1094 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1095 buffer_put_cstring(&b, authctxt->server_user);
1096 buffer_put_cstring(&b,
1097 datafellows & SSH_BUG_PKSERVICE ?
1098 "ssh-userauth" :
1099 authctxt->service);
1100 if (datafellows & SSH_BUG_PKAUTH) {
1101 buffer_put_char(&b, have_sig);
1102 } else {
1103 buffer_put_cstring(&b, authctxt->method->name);
1104 buffer_put_char(&b, have_sig);
1105 buffer_put_cstring(&b, key_sign_encode(id->key));
1106 }
1107 buffer_put_string(&b, blob, bloblen);
1108
1109 /*
1110 * If the key is an certificate, try to find a matching private key
1111 * and use it to complete the signature.
1112 * If no such private key exists, fall back to trying the certificate
1113 * key itself in case it has a private half already loaded.
1114 */
1115 if (key_is_cert(id->key)) {
1116 matched = 0;
1117 TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1118 if (sshkey_equal_public(id->key, private_id->key) &&
1119 id->key->type != private_id->key->type) {
1120 id = private_id;
1121 matched = 1;
1122 break;
1123 }
1124 }
1125 /*
1126 * Exact key matches are preferred, but also allow
1127 * filename matches for non-PKCS#11/agent keys that
1128 * didn't load public keys. This supports the case
1129 * of keeping just a private key file and public
1130 * certificate on disk.
1131 */
1132 if (!matched && !id->isprivate && id->agent_fd == -1 &&
1133 (id->key->flags & SSHKEY_FLAG_EXT) == 0) {
1134 TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1135 if (private_id->key == NULL &&
1136 id_filename_matches(id, private_id)) {
1137 id = private_id;
1138 matched = 1;
1139 break;
1140 }
1141 }
1142 }
1143 if (matched) {
1144 debug2("%s: using private key \"%s\"%s for "
1145 "certificate", __func__, id->filename,
1146 id->agent_fd != -1 ? " from agent" : "");
1147 } else {
1148 debug("%s: no separate private key for certificate "
1149 "\"%s\"", __func__, id->filename);
1150 }
1151 }
1152
1153 /* generate signature */
1154 ret = identity_sign(id, &signature, &slen,
1155 buffer_ptr(&b), buffer_len(&b), datafellows);
1156 if (ret != 0) {
1157 if (ret != SSH_ERR_KEY_NOT_FOUND)
1158 error("%s: signing failed: %s", __func__, ssh_err(ret));
1159 free(blob);
1160 buffer_free(&b);
1161 return 0;
1162 }
1163 #ifdef DEBUG_PK
1164 buffer_dump(&b);
1165 #endif
1166 if (datafellows & SSH_BUG_PKSERVICE) {
1167 buffer_clear(&b);
1168 buffer_append(&b, session_id2, session_id2_len);
1169 skip = session_id2_len;
1170 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1171 buffer_put_cstring(&b, authctxt->server_user);
1172 buffer_put_cstring(&b, authctxt->service);
1173 buffer_put_cstring(&b, authctxt->method->name);
1174 buffer_put_char(&b, have_sig);
1175 if (!(datafellows & SSH_BUG_PKAUTH))
1176 buffer_put_cstring(&b, key_ssh_name(id->key));
1177 buffer_put_string(&b, blob, bloblen);
1178 }
1179 free(blob);
1180
1181 /* append signature */
1182 buffer_put_string(&b, signature, slen);
1183 free(signature);
1184
1185 /* skip session id and packet type */
1186 if (buffer_len(&b) < skip + 1)
1187 fatal("userauth_pubkey: internal error");
1188 buffer_consume(&b, skip + 1);
1189
1190 /* put remaining data from buffer into packet */
1191 packet_start(SSH2_MSG_USERAUTH_REQUEST);
1192 packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1193 buffer_free(&b);
1194 packet_send();
1195
1196 return 1;
1197 }
1198
1199 static int
send_pubkey_test(Authctxt * authctxt,Identity * id)1200 send_pubkey_test(Authctxt *authctxt, Identity *id)
1201 {
1202 u_char *blob;
1203 u_int bloblen, have_sig = 0;
1204
1205 debug3("send_pubkey_test");
1206
1207 if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1208 /* we cannot handle this key */
1209 debug3("send_pubkey_test: cannot handle key");
1210 return 0;
1211 }
1212 /* register callback for USERAUTH_PK_OK message */
1213 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1214
1215 packet_start(SSH2_MSG_USERAUTH_REQUEST);
1216 packet_put_cstring(authctxt->server_user);
1217 packet_put_cstring(authctxt->service);
1218 packet_put_cstring(authctxt->method->name);
1219 packet_put_char(have_sig);
1220 if (!(datafellows & SSH_BUG_PKAUTH))
1221 packet_put_cstring(key_sign_encode(id->key));
1222 packet_put_string(blob, bloblen);
1223 free(blob);
1224 packet_send();
1225 return 1;
1226 }
1227
1228 static Key *
load_identity_file(Identity * id)1229 load_identity_file(Identity *id)
1230 {
1231 Key *private = NULL;
1232 char prompt[300], *passphrase, *comment;
1233 int r, perm_ok = 0, quit = 0, i;
1234 struct stat st;
1235
1236 if (stat(id->filename, &st) < 0) {
1237 (id->userprovided ? logit : debug3)("no such identity: %s: %s",
1238 id->filename, strerror(errno));
1239 return NULL;
1240 }
1241 snprintf(prompt, sizeof prompt,
1242 "Enter passphrase for key '%.100s': ", id->filename);
1243 for (i = 0; i <= options.number_of_password_prompts; i++) {
1244 if (i == 0)
1245 passphrase = "";
1246 else {
1247 passphrase = read_passphrase(prompt, 0);
1248 if (*passphrase == '\0') {
1249 debug2("no passphrase given, try next key");
1250 free(passphrase);
1251 break;
1252 }
1253 }
1254 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename,
1255 passphrase, &private, &comment, &perm_ok))) {
1256 case 0:
1257 break;
1258 case SSH_ERR_KEY_WRONG_PASSPHRASE:
1259 if (options.batch_mode) {
1260 quit = 1;
1261 break;
1262 }
1263 if (i != 0)
1264 debug2("bad passphrase given, try again...");
1265 break;
1266 case SSH_ERR_SYSTEM_ERROR:
1267 if (errno == ENOENT) {
1268 debug2("Load key \"%s\": %s",
1269 id->filename, ssh_err(r));
1270 quit = 1;
1271 break;
1272 }
1273 /* FALLTHROUGH */
1274 default:
1275 error("Load key \"%s\": %s", id->filename, ssh_err(r));
1276 quit = 1;
1277 break;
1278 }
1279 if (!quit && private != NULL && id->agent_fd == -1 &&
1280 !(id->key && id->isprivate))
1281 maybe_add_key_to_agent(id->filename, private, comment,
1282 passphrase);
1283 if (i > 0) {
1284 explicit_bzero(passphrase, strlen(passphrase));
1285 free(passphrase);
1286 }
1287 free(comment);
1288 if (private != NULL || quit)
1289 break;
1290 }
1291 return private;
1292 }
1293
1294 /*
1295 * try keys in the following order:
1296 * 1. certificates listed in the config file
1297 * 2. other input certificates
1298 * 3. agent keys that are found in the config file
1299 * 4. other agent keys
1300 * 5. keys that are only listed in the config file
1301 */
1302 static void
pubkey_prepare(Authctxt * authctxt)1303 pubkey_prepare(Authctxt *authctxt)
1304 {
1305 struct identity *id, *id2, *tmp;
1306 struct idlist agent, files, *preferred;
1307 struct sshkey *key;
1308 int agent_fd = -1, i, r, found;
1309 size_t j;
1310 struct ssh_identitylist *idlist;
1311
1312 TAILQ_INIT(&agent); /* keys from the agent */
1313 TAILQ_INIT(&files); /* keys from the config file */
1314 preferred = &authctxt->keys;
1315 TAILQ_INIT(preferred); /* preferred order of keys */
1316
1317 /* list of keys stored in the filesystem and PKCS#11 */
1318 for (i = 0; i < options.num_identity_files; i++) {
1319 key = options.identity_keys[i];
1320 if (key && key->type == KEY_RSA1)
1321 continue;
1322 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1323 continue;
1324 options.identity_keys[i] = NULL;
1325 id = xcalloc(1, sizeof(*id));
1326 id->agent_fd = -1;
1327 id->key = key;
1328 id->filename = xstrdup(options.identity_files[i]);
1329 id->userprovided = options.identity_file_userprovided[i];
1330 TAILQ_INSERT_TAIL(&files, id, next);
1331 }
1332 /* list of certificates specified by user */
1333 for (i = 0; i < options.num_certificate_files; i++) {
1334 key = options.certificates[i];
1335 if (!key_is_cert(key) || key->cert == NULL ||
1336 key->cert->type != SSH2_CERT_TYPE_USER)
1337 continue;
1338 id = xcalloc(1, sizeof(*id));
1339 id->agent_fd = -1;
1340 id->key = key;
1341 id->filename = xstrdup(options.certificate_files[i]);
1342 id->userprovided = options.certificate_file_userprovided[i];
1343 TAILQ_INSERT_TAIL(preferred, id, next);
1344 }
1345 /* list of keys supported by the agent */
1346 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) {
1347 if (r != SSH_ERR_AGENT_NOT_PRESENT)
1348 debug("%s: ssh_get_authentication_socket: %s",
1349 __func__, ssh_err(r));
1350 } else if ((r = ssh_fetch_identitylist(agent_fd, 2, &idlist)) != 0) {
1351 if (r != SSH_ERR_AGENT_NO_IDENTITIES)
1352 debug("%s: ssh_fetch_identitylist: %s",
1353 __func__, ssh_err(r));
1354 close(agent_fd);
1355 } else {
1356 for (j = 0; j < idlist->nkeys; j++) {
1357 found = 0;
1358 TAILQ_FOREACH(id, &files, next) {
1359 /*
1360 * agent keys from the config file are
1361 * preferred
1362 */
1363 if (sshkey_equal(idlist->keys[j], id->key)) {
1364 TAILQ_REMOVE(&files, id, next);
1365 TAILQ_INSERT_TAIL(preferred, id, next);
1366 id->agent_fd = agent_fd;
1367 found = 1;
1368 break;
1369 }
1370 }
1371 if (!found && !options.identities_only) {
1372 id = xcalloc(1, sizeof(*id));
1373 /* XXX "steals" key/comment from idlist */
1374 id->key = idlist->keys[j];
1375 id->filename = idlist->comments[j];
1376 idlist->keys[j] = NULL;
1377 idlist->comments[j] = NULL;
1378 id->agent_fd = agent_fd;
1379 TAILQ_INSERT_TAIL(&agent, id, next);
1380 }
1381 }
1382 ssh_free_identitylist(idlist);
1383 /* append remaining agent keys */
1384 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1385 TAILQ_REMOVE(&agent, id, next);
1386 TAILQ_INSERT_TAIL(preferred, id, next);
1387 }
1388 authctxt->agent_fd = agent_fd;
1389 }
1390 /* Prefer PKCS11 keys that are explicitly listed */
1391 TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1392 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0)
1393 continue;
1394 found = 0;
1395 TAILQ_FOREACH(id2, &files, next) {
1396 if (id2->key == NULL ||
1397 (id2->key->flags & SSHKEY_FLAG_EXT) == 0)
1398 continue;
1399 if (sshkey_equal(id->key, id2->key)) {
1400 TAILQ_REMOVE(&files, id, next);
1401 TAILQ_INSERT_TAIL(preferred, id, next);
1402 found = 1;
1403 break;
1404 }
1405 }
1406 /* If IdentitiesOnly set and key not found then don't use it */
1407 if (!found && options.identities_only) {
1408 TAILQ_REMOVE(&files, id, next);
1409 explicit_bzero(id, sizeof(*id));
1410 free(id);
1411 }
1412 }
1413 /* append remaining keys from the config file */
1414 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1415 TAILQ_REMOVE(&files, id, next);
1416 TAILQ_INSERT_TAIL(preferred, id, next);
1417 }
1418 /* finally, filter by PubkeyAcceptedKeyTypes */
1419 TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
1420 if (id->key != NULL &&
1421 match_pattern_list(sshkey_ssh_name(id->key),
1422 options.pubkey_key_types, 0) != 1) {
1423 debug("Skipping %s key %s - "
1424 "not in PubkeyAcceptedKeyTypes",
1425 sshkey_ssh_name(id->key), id->filename);
1426 TAILQ_REMOVE(preferred, id, next);
1427 sshkey_free(id->key);
1428 free(id->filename);
1429 memset(id, 0, sizeof(*id));
1430 continue;
1431 }
1432 debug2("key: %s (%p)%s%s", id->filename, id->key,
1433 id->userprovided ? ", explicit" : "",
1434 id->agent_fd != -1 ? ", agent" : "");
1435 }
1436 }
1437
1438 static void
pubkey_cleanup(Authctxt * authctxt)1439 pubkey_cleanup(Authctxt *authctxt)
1440 {
1441 Identity *id;
1442
1443 if (authctxt->agent_fd != -1)
1444 ssh_close_authentication_socket(authctxt->agent_fd);
1445 for (id = TAILQ_FIRST(&authctxt->keys); id;
1446 id = TAILQ_FIRST(&authctxt->keys)) {
1447 TAILQ_REMOVE(&authctxt->keys, id, next);
1448 sshkey_free(id->key);
1449 free(id->filename);
1450 free(id);
1451 }
1452 }
1453
1454 static void
pubkey_reset(Authctxt * authctxt)1455 pubkey_reset(Authctxt *authctxt)
1456 {
1457 Identity *id;
1458
1459 TAILQ_FOREACH(id, &authctxt->keys, next)
1460 id->tried = 0;
1461 }
1462
1463 static int
try_identity(Identity * id)1464 try_identity(Identity *id)
1465 {
1466 if (!id->key)
1467 return (0);
1468 if (key_type_plain(id->key->type) == KEY_RSA &&
1469 (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1470 debug("Skipped %s key %s for RSA/MD5 server",
1471 key_type(id->key), id->filename);
1472 return (0);
1473 }
1474 return (id->key->type != KEY_RSA1);
1475 }
1476
1477 int
userauth_pubkey(Authctxt * authctxt)1478 userauth_pubkey(Authctxt *authctxt)
1479 {
1480 Identity *id;
1481 int sent = 0;
1482
1483 while ((id = TAILQ_FIRST(&authctxt->keys))) {
1484 if (id->tried++)
1485 return (0);
1486 /* move key to the end of the queue */
1487 TAILQ_REMOVE(&authctxt->keys, id, next);
1488 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1489 /*
1490 * send a test message if we have the public key. for
1491 * encrypted keys we cannot do this and have to load the
1492 * private key instead
1493 */
1494 if (id->key != NULL) {
1495 if (try_identity(id)) {
1496 debug("Offering %s public key: %s",
1497 key_type(id->key), id->filename);
1498 sent = send_pubkey_test(authctxt, id);
1499 }
1500 } else {
1501 debug("Trying private key: %s", id->filename);
1502 id->key = load_identity_file(id);
1503 if (id->key != NULL) {
1504 if (try_identity(id)) {
1505 id->isprivate = 1;
1506 sent = sign_and_send_pubkey(
1507 authctxt, id);
1508 }
1509 key_free(id->key);
1510 id->key = NULL;
1511 id->isprivate = 0;
1512 }
1513 }
1514 if (sent)
1515 return (sent);
1516 }
1517 return (0);
1518 }
1519
1520 /*
1521 * Send userauth request message specifying keyboard-interactive method.
1522 */
1523 int
userauth_kbdint(Authctxt * authctxt)1524 userauth_kbdint(Authctxt *authctxt)
1525 {
1526 static int attempt = 0;
1527
1528 if (attempt++ >= options.number_of_password_prompts)
1529 return 0;
1530 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1531 if (attempt > 1 && !authctxt->info_req_seen) {
1532 debug3("userauth_kbdint: disable: no info_req_seen");
1533 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1534 return 0;
1535 }
1536
1537 debug2("userauth_kbdint");
1538 packet_start(SSH2_MSG_USERAUTH_REQUEST);
1539 packet_put_cstring(authctxt->server_user);
1540 packet_put_cstring(authctxt->service);
1541 packet_put_cstring(authctxt->method->name);
1542 packet_put_cstring(""); /* lang */
1543 packet_put_cstring(options.kbd_interactive_devices ?
1544 options.kbd_interactive_devices : "");
1545 packet_send();
1546
1547 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1548 return 1;
1549 }
1550
1551 /*
1552 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1553 */
1554 int
input_userauth_info_req(int type,u_int32_t seq,void * ctxt)1555 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1556 {
1557 Authctxt *authctxt = ctxt;
1558 char *name, *inst, *lang, *prompt, *response;
1559 u_int num_prompts, i;
1560 int echo = 0;
1561
1562 debug2("input_userauth_info_req");
1563
1564 if (authctxt == NULL)
1565 fatal("input_userauth_info_req: no authentication context");
1566
1567 authctxt->info_req_seen = 1;
1568
1569 name = packet_get_string(NULL);
1570 inst = packet_get_string(NULL);
1571 lang = packet_get_string(NULL);
1572 if (strlen(name) > 0)
1573 logit("%s", name);
1574 if (strlen(inst) > 0)
1575 logit("%s", inst);
1576 free(name);
1577 free(inst);
1578 free(lang);
1579
1580 num_prompts = packet_get_int();
1581 /*
1582 * Begin to build info response packet based on prompts requested.
1583 * We commit to providing the correct number of responses, so if
1584 * further on we run into a problem that prevents this, we have to
1585 * be sure and clean this up and send a correct error response.
1586 */
1587 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1588 packet_put_int(num_prompts);
1589
1590 debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1591 for (i = 0; i < num_prompts; i++) {
1592 prompt = packet_get_string(NULL);
1593 echo = packet_get_char();
1594
1595 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1596
1597 packet_put_cstring(response);
1598 explicit_bzero(response, strlen(response));
1599 free(response);
1600 free(prompt);
1601 }
1602 packet_check_eom(); /* done with parsing incoming message. */
1603
1604 packet_add_padding(64);
1605 packet_send();
1606 return 0;
1607 }
1608
1609 static int
ssh_keysign(struct sshkey * key,u_char ** sigp,size_t * lenp,const u_char * data,size_t datalen)1610 ssh_keysign(struct sshkey *key, u_char **sigp, size_t *lenp,
1611 const u_char *data, size_t datalen)
1612 {
1613 struct sshbuf *b;
1614 struct stat st;
1615 pid_t pid;
1616 int i, r, to[2], from[2], status, sock = packet_get_connection_in();
1617 u_char rversion = 0, version = 2;
1618 void (*osigchld)(int);
1619
1620 *sigp = NULL;
1621 *lenp = 0;
1622
1623 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1624 error("%s: not installed: %s", __func__, strerror(errno));
1625 return -1;
1626 }
1627 if (fflush(stdout) != 0) {
1628 error("%s: fflush: %s", __func__, strerror(errno));
1629 return -1;
1630 }
1631 if (pipe(to) < 0) {
1632 error("%s: pipe: %s", __func__, strerror(errno));
1633 return -1;
1634 }
1635 if (pipe(from) < 0) {
1636 error("%s: pipe: %s", __func__, strerror(errno));
1637 return -1;
1638 }
1639 if ((pid = fork()) < 0) {
1640 error("%s: fork: %s", __func__, strerror(errno));
1641 return -1;
1642 }
1643 osigchld = signal(SIGCHLD, SIG_DFL);
1644 if (pid == 0) {
1645 /* keep the socket on exec */
1646 fcntl(sock, F_SETFD, 0);
1647 permanently_drop_suid(getuid());
1648 close(from[0]);
1649 if (dup2(from[1], STDOUT_FILENO) < 0)
1650 fatal("%s: dup2: %s", __func__, strerror(errno));
1651 close(to[1]);
1652 if (dup2(to[0], STDIN_FILENO) < 0)
1653 fatal("%s: dup2: %s", __func__, strerror(errno));
1654 close(from[1]);
1655 close(to[0]);
1656 /* Close everything but stdio and the socket */
1657 for (i = STDERR_FILENO + 1; i < sock; i++)
1658 close(i);
1659 closefrom(sock + 1);
1660 debug3("%s: [child] pid=%ld, exec %s",
1661 __func__, (long)getpid(), _PATH_SSH_KEY_SIGN);
1662 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL);
1663 fatal("%s: exec(%s): %s", __func__, _PATH_SSH_KEY_SIGN,
1664 strerror(errno));
1665 }
1666 close(from[1]);
1667 close(to[0]);
1668
1669 if ((b = sshbuf_new()) == NULL)
1670 fatal("%s: sshbuf_new failed", __func__);
1671 /* send # of sock, data to be signed */
1672 if ((r = sshbuf_put_u32(b, sock)) != 0 ||
1673 (r = sshbuf_put_string(b, data, datalen)) != 0)
1674 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1675 if (ssh_msg_send(to[1], version, b) == -1)
1676 fatal("%s: couldn't send request", __func__);
1677 sshbuf_reset(b);
1678 r = ssh_msg_recv(from[0], b);
1679 close(from[0]);
1680 close(to[1]);
1681 if (r < 0) {
1682 error("%s: no reply", __func__);
1683 goto fail;
1684 }
1685
1686 errno = 0;
1687 while (waitpid(pid, &status, 0) < 0) {
1688 if (errno != EINTR) {
1689 error("%s: waitpid %ld: %s",
1690 __func__, (long)pid, strerror(errno));
1691 goto fail;
1692 }
1693 }
1694 if (!WIFEXITED(status)) {
1695 error("%s: exited abnormally", __func__);
1696 goto fail;
1697 }
1698 if (WEXITSTATUS(status) != 0) {
1699 error("%s: exited with status %d",
1700 __func__, WEXITSTATUS(status));
1701 goto fail;
1702 }
1703 if ((r = sshbuf_get_u8(b, &rversion)) != 0) {
1704 error("%s: buffer error: %s", __func__, ssh_err(r));
1705 goto fail;
1706 }
1707 if (rversion != version) {
1708 error("%s: bad version", __func__);
1709 goto fail;
1710 }
1711 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) {
1712 error("%s: buffer error: %s", __func__, ssh_err(r));
1713 fail:
1714 signal(SIGCHLD, osigchld);
1715 sshbuf_free(b);
1716 return -1;
1717 }
1718 signal(SIGCHLD, osigchld);
1719 sshbuf_free(b);
1720
1721 return 0;
1722 }
1723
1724 int
userauth_hostbased(Authctxt * authctxt)1725 userauth_hostbased(Authctxt *authctxt)
1726 {
1727 struct ssh *ssh = active_state;
1728 struct sshkey *private = NULL;
1729 struct sshbuf *b = NULL;
1730 const char *service;
1731 u_char *sig = NULL, *keyblob = NULL;
1732 char *fp = NULL, *chost = NULL, *lname = NULL;
1733 size_t siglen = 0, keylen = 0;
1734 int i, r, success = 0;
1735
1736 if (authctxt->ktypes == NULL) {
1737 authctxt->oktypes = xstrdup(options.hostbased_key_types);
1738 authctxt->ktypes = authctxt->oktypes;
1739 }
1740
1741 /*
1742 * Work through each listed type pattern in HostbasedKeyTypes,
1743 * trying each hostkey that matches the type in turn.
1744 */
1745 for (;;) {
1746 if (authctxt->active_ktype == NULL)
1747 authctxt->active_ktype = strsep(&authctxt->ktypes, ",");
1748 if (authctxt->active_ktype == NULL ||
1749 *authctxt->active_ktype == '\0')
1750 break;
1751 debug3("%s: trying key type %s", __func__,
1752 authctxt->active_ktype);
1753
1754 /* check for a useful key */
1755 private = NULL;
1756 for (i = 0; i < authctxt->sensitive->nkeys; i++) {
1757 if (authctxt->sensitive->keys[i] == NULL ||
1758 authctxt->sensitive->keys[i]->type == KEY_RSA1 ||
1759 authctxt->sensitive->keys[i]->type == KEY_UNSPEC)
1760 continue;
1761 if (match_pattern_list(
1762 sshkey_ssh_name(authctxt->sensitive->keys[i]),
1763 authctxt->active_ktype, 0) != 1)
1764 continue;
1765 /* we take and free the key */
1766 private = authctxt->sensitive->keys[i];
1767 authctxt->sensitive->keys[i] = NULL;
1768 break;
1769 }
1770 /* Found one */
1771 if (private != NULL)
1772 break;
1773 /* No more keys of this type; advance */
1774 authctxt->active_ktype = NULL;
1775 }
1776 if (private == NULL) {
1777 free(authctxt->oktypes);
1778 authctxt->oktypes = authctxt->ktypes = NULL;
1779 authctxt->active_ktype = NULL;
1780 debug("No more client hostkeys for hostbased authentication.");
1781 goto out;
1782 }
1783
1784 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash,
1785 SSH_FP_DEFAULT)) == NULL) {
1786 error("%s: sshkey_fingerprint failed", __func__);
1787 goto out;
1788 }
1789 debug("%s: trying hostkey %s %s",
1790 __func__, sshkey_ssh_name(private), fp);
1791
1792 /* figure out a name for the client host */
1793 if ((lname = get_local_name(packet_get_connection_in())) == NULL) {
1794 error("%s: cannot get local ipaddr/name", __func__);
1795 goto out;
1796 }
1797
1798 /* XXX sshbuf_put_stringf? */
1799 xasprintf(&chost, "%s.", lname);
1800 debug2("%s: chost %s", __func__, chost);
1801
1802 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1803 authctxt->service;
1804
1805 /* construct data */
1806 if ((b = sshbuf_new()) == NULL) {
1807 error("%s: sshbuf_new failed", __func__);
1808 goto out;
1809 }
1810 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) {
1811 error("%s: sshkey_to_blob: %s", __func__, ssh_err(r));
1812 goto out;
1813 }
1814 if ((r = sshbuf_put_string(b, session_id2, session_id2_len)) != 0 ||
1815 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1816 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
1817 (r = sshbuf_put_cstring(b, service)) != 0 ||
1818 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
1819 (r = sshbuf_put_cstring(b, key_ssh_name(private))) != 0 ||
1820 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 ||
1821 (r = sshbuf_put_cstring(b, chost)) != 0 ||
1822 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) {
1823 error("%s: buffer error: %s", __func__, ssh_err(r));
1824 goto out;
1825 }
1826
1827 #ifdef DEBUG_PK
1828 sshbuf_dump(b, stderr);
1829 #endif
1830 if (authctxt->sensitive->external_keysign)
1831 r = ssh_keysign(private, &sig, &siglen,
1832 sshbuf_ptr(b), sshbuf_len(b));
1833 else if ((r = sshkey_sign(private, &sig, &siglen,
1834 sshbuf_ptr(b), sshbuf_len(b), NULL, datafellows)) != 0)
1835 debug("%s: sshkey_sign: %s", __func__, ssh_err(r));
1836 if (r != 0) {
1837 error("sign using hostkey %s %s failed",
1838 sshkey_ssh_name(private), fp);
1839 goto out;
1840 }
1841 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1842 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1843 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1844 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1845 (r = sshpkt_put_cstring(ssh, key_ssh_name(private))) != 0 ||
1846 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 ||
1847 (r = sshpkt_put_cstring(ssh, chost)) != 0 ||
1848 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 ||
1849 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 ||
1850 (r = sshpkt_send(ssh)) != 0) {
1851 error("%s: packet error: %s", __func__, ssh_err(r));
1852 goto out;
1853 }
1854 success = 1;
1855
1856 out:
1857 if (sig != NULL) {
1858 explicit_bzero(sig, siglen);
1859 free(sig);
1860 }
1861 free(keyblob);
1862 free(lname);
1863 free(fp);
1864 free(chost);
1865 sshkey_free(private);
1866 sshbuf_free(b);
1867
1868 return success;
1869 }
1870
1871 /* find auth method */
1872
1873 /*
1874 * given auth method name, if configurable options permit this method fill
1875 * in auth_ident field and return true, otherwise return false.
1876 */
1877 static int
authmethod_is_enabled(Authmethod * method)1878 authmethod_is_enabled(Authmethod *method)
1879 {
1880 if (method == NULL)
1881 return 0;
1882 /* return false if options indicate this method is disabled */
1883 if (method->enabled == NULL || *method->enabled == 0)
1884 return 0;
1885 /* return false if batch mode is enabled but method needs interactive mode */
1886 if (method->batch_flag != NULL && *method->batch_flag != 0)
1887 return 0;
1888 return 1;
1889 }
1890
1891 static Authmethod *
authmethod_lookup(const char * name)1892 authmethod_lookup(const char *name)
1893 {
1894 Authmethod *method = NULL;
1895 if (name != NULL)
1896 for (method = authmethods; method->name != NULL; method++)
1897 if (strcmp(name, method->name) == 0)
1898 return method;
1899 debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1900 return NULL;
1901 }
1902
1903 /* XXX internal state */
1904 static Authmethod *current = NULL;
1905 static char *supported = NULL;
1906 static char *preferred = NULL;
1907
1908 /*
1909 * Given the authentication method list sent by the server, return the
1910 * next method we should try. If the server initially sends a nil list,
1911 * use a built-in default list.
1912 */
1913 static Authmethod *
authmethod_get(char * authlist)1914 authmethod_get(char *authlist)
1915 {
1916 char *name = NULL;
1917 u_int next;
1918
1919 /* Use a suitable default if we're passed a nil list. */
1920 if (authlist == NULL || strlen(authlist) == 0)
1921 authlist = options.preferred_authentications;
1922
1923 if (supported == NULL || strcmp(authlist, supported) != 0) {
1924 debug3("start over, passed a different list %s", authlist);
1925 free(supported);
1926 supported = xstrdup(authlist);
1927 preferred = options.preferred_authentications;
1928 debug3("preferred %s", preferred);
1929 current = NULL;
1930 } else if (current != NULL && authmethod_is_enabled(current))
1931 return current;
1932
1933 for (;;) {
1934 if ((name = match_list(preferred, supported, &next)) == NULL) {
1935 debug("No more authentication methods to try.");
1936 current = NULL;
1937 return NULL;
1938 }
1939 preferred += next;
1940 debug3("authmethod_lookup %s", name);
1941 debug3("remaining preferred: %s", preferred);
1942 if ((current = authmethod_lookup(name)) != NULL &&
1943 authmethod_is_enabled(current)) {
1944 debug3("authmethod_is_enabled %s", name);
1945 debug("Next authentication method: %s", name);
1946 free(name);
1947 return current;
1948 }
1949 free(name);
1950 }
1951 }
1952
1953 static char *
authmethods_get(void)1954 authmethods_get(void)
1955 {
1956 Authmethod *method = NULL;
1957 Buffer b;
1958 char *list;
1959
1960 buffer_init(&b);
1961 for (method = authmethods; method->name != NULL; method++) {
1962 if (authmethod_is_enabled(method)) {
1963 if (buffer_len(&b) > 0)
1964 buffer_append(&b, ",", 1);
1965 buffer_append(&b, method->name, strlen(method->name));
1966 }
1967 }
1968 if ((list = sshbuf_dup_string(&b)) == NULL)
1969 fatal("%s: sshbuf_dup_string failed", __func__);
1970 buffer_free(&b);
1971 return list;
1972 }
1973
1974