1 /* $OpenBSD: sshconnect2.c,v 1.204 2014/02/02 03:44:32 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 "readconf.h"
65 #include "misc.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
74 #ifdef GSSAPI
75 #include "ssh-gss.h"
76 #endif
77
78 /* import */
79 extern char *client_version_string;
80 extern char *server_version_string;
81 extern Options options;
82
83 /*
84 * SSH2 key exchange
85 */
86
87 u_char *session_id2 = NULL;
88 u_int session_id2_len = 0;
89
90 char *xxx_host;
91 struct sockaddr *xxx_hostaddr;
92
93 Kex *xxx_kex = NULL;
94
95 static int
verify_host_key_callback(Key * hostkey)96 verify_host_key_callback(Key *hostkey)
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 = key_type_from_name(alg)) == KEY_UNSPEC)
135 fatal("%s: unknown alg %s", __func__, alg);
136 if (lookup_key_in_hostkeys_by_type(hostkeys,
137 key_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, *first == '\0' ? "" : ",", last);
144 if (*first != '\0')
145 debug3("%s: prefer hostkeyalgs: %s", __func__, first);
146
147 free(first);
148 free(last);
149 free(hostname);
150 free(oavail);
151 free_hostkeys(hostkeys);
152
153 return ret;
154 }
155
156 void
ssh_kex2(char * host,struct sockaddr * hostaddr,u_short port)157 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
158 {
159 Kex *kex;
160
161 xxx_host = host;
162 xxx_hostaddr = hostaddr;
163
164 if (options.ciphers == (char *)-1) {
165 logit("No valid ciphers for protocol version 2 given, using defaults.");
166 options.ciphers = NULL;
167 }
168 if (options.ciphers != NULL) {
169 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
170 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
171 }
172 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
173 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
174 myproposal[PROPOSAL_ENC_ALGS_STOC] =
175 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
176 if (options.compression) {
177 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
178 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
179 } else {
180 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
181 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
182 }
183 if (options.macs != NULL) {
184 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
185 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
186 }
187 if (options.hostkeyalgorithms != NULL)
188 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
189 compat_pkalg_proposal(options.hostkeyalgorithms);
190 else {
191 /* Prefer algorithms that we already have keys for */
192 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
193 compat_pkalg_proposal(
194 order_hostkeyalgs(host, hostaddr, port));
195 }
196 if (options.kex_algorithms != NULL)
197 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
198 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
199 myproposal[PROPOSAL_KEX_ALGS]);
200
201 if (options.rekey_limit || options.rekey_interval)
202 packet_set_rekey_limits((u_int32_t)options.rekey_limit,
203 (time_t)options.rekey_interval);
204
205 /* start key exchange */
206 kex = kex_setup(myproposal);
207 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
208 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
209 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
210 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
211 kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
212 kex->kex[KEX_C25519_SHA256] = kexc25519_client;
213 kex->client_version_string=client_version_string;
214 kex->server_version_string=server_version_string;
215 kex->verify_host_key=&verify_host_key_callback;
216
217 xxx_kex = kex;
218
219 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
220
221 if (options.use_roaming && !kex->roaming) {
222 debug("Roaming not allowed by server");
223 options.use_roaming = 0;
224 }
225
226 session_id2 = kex->session_id;
227 session_id2_len = kex->session_id_len;
228
229 #ifdef DEBUG_KEXDH
230 /* send 1st encrypted/maced/compressed message */
231 packet_start(SSH2_MSG_IGNORE);
232 packet_put_cstring("markus");
233 packet_send();
234 packet_write_wait();
235 #endif
236 }
237
238 /*
239 * Authenticate user
240 */
241
242 typedef struct Authctxt Authctxt;
243 typedef struct Authmethod Authmethod;
244 typedef struct identity Identity;
245 typedef struct idlist Idlist;
246
247 struct identity {
248 TAILQ_ENTRY(identity) next;
249 AuthenticationConnection *ac; /* set if agent supports key */
250 Key *key; /* public/private key */
251 char *filename; /* comment for agent-only keys */
252 int tried;
253 int isprivate; /* key points to the private key */
254 int userprovided;
255 };
256 TAILQ_HEAD(idlist, identity);
257
258 struct Authctxt {
259 const char *server_user;
260 const char *local_user;
261 const char *host;
262 const char *service;
263 Authmethod *method;
264 sig_atomic_t success;
265 char *authlist;
266 /* pubkey */
267 Idlist keys;
268 AuthenticationConnection *agent;
269 /* hostbased */
270 Sensitive *sensitive;
271 /* kbd-interactive */
272 int info_req_seen;
273 /* generic */
274 void *methoddata;
275 };
276 struct Authmethod {
277 char *name; /* string to compare against server's list */
278 int (*userauth)(Authctxt *authctxt);
279 void (*cleanup)(Authctxt *authctxt);
280 int *enabled; /* flag in option struct that enables method */
281 int *batch_flag; /* flag in option struct that disables method */
282 };
283
284 void input_userauth_success(int, u_int32_t, void *);
285 void input_userauth_success_unexpected(int, u_int32_t, void *);
286 void input_userauth_failure(int, u_int32_t, void *);
287 void input_userauth_banner(int, u_int32_t, void *);
288 void input_userauth_error(int, u_int32_t, void *);
289 void input_userauth_info_req(int, u_int32_t, void *);
290 void input_userauth_pk_ok(int, u_int32_t, void *);
291 void input_userauth_passwd_changereq(int, u_int32_t, void *);
292
293 int userauth_none(Authctxt *);
294 int userauth_pubkey(Authctxt *);
295 int userauth_passwd(Authctxt *);
296 int userauth_kbdint(Authctxt *);
297 int userauth_hostbased(Authctxt *);
298
299 #ifdef GSSAPI
300 int userauth_gssapi(Authctxt *authctxt);
301 void input_gssapi_response(int type, u_int32_t, void *);
302 void input_gssapi_token(int type, u_int32_t, void *);
303 void input_gssapi_hash(int type, u_int32_t, void *);
304 void input_gssapi_error(int, u_int32_t, void *);
305 void input_gssapi_errtok(int, u_int32_t, void *);
306 #endif
307
308 void userauth(Authctxt *, char *);
309
310 static int sign_and_send_pubkey(Authctxt *, Identity *);
311 static void pubkey_prepare(Authctxt *);
312 static void pubkey_cleanup(Authctxt *);
313 static Key *load_identity_file(char *, int);
314
315 static Authmethod *authmethod_get(char *authlist);
316 static Authmethod *authmethod_lookup(const char *name);
317 static char *authmethods_get(void);
318
319 Authmethod authmethods[] = {
320 #ifdef GSSAPI
321 {"gssapi-with-mic",
322 userauth_gssapi,
323 NULL,
324 &options.gss_authentication,
325 NULL},
326 #endif
327 {"hostbased",
328 userauth_hostbased,
329 NULL,
330 &options.hostbased_authentication,
331 NULL},
332 {"publickey",
333 userauth_pubkey,
334 NULL,
335 &options.pubkey_authentication,
336 NULL},
337 {"keyboard-interactive",
338 userauth_kbdint,
339 NULL,
340 &options.kbd_interactive_authentication,
341 &options.batch_mode},
342 {"password",
343 userauth_passwd,
344 NULL,
345 &options.password_authentication,
346 &options.batch_mode},
347 {"none",
348 userauth_none,
349 NULL,
350 NULL,
351 NULL},
352 {NULL, NULL, NULL, NULL, NULL}
353 };
354
355 void
ssh_userauth2(const char * local_user,const char * server_user,char * host,Sensitive * sensitive)356 ssh_userauth2(const char *local_user, const char *server_user, char *host,
357 Sensitive *sensitive)
358 {
359 Authctxt authctxt;
360 int type;
361
362 if (options.challenge_response_authentication)
363 options.kbd_interactive_authentication = 1;
364
365 packet_start(SSH2_MSG_SERVICE_REQUEST);
366 packet_put_cstring("ssh-userauth");
367 packet_send();
368 debug("SSH2_MSG_SERVICE_REQUEST sent");
369 packet_write_wait();
370 type = packet_read();
371 if (type != SSH2_MSG_SERVICE_ACCEPT)
372 fatal("Server denied authentication request: %d", type);
373 if (packet_remaining() > 0) {
374 char *reply = packet_get_string(NULL);
375 debug2("service_accept: %s", reply);
376 free(reply);
377 } else {
378 debug2("buggy server: service_accept w/o service");
379 }
380 packet_check_eom();
381 debug("SSH2_MSG_SERVICE_ACCEPT received");
382
383 if (options.preferred_authentications == NULL)
384 options.preferred_authentications = authmethods_get();
385
386 /* setup authentication context */
387 memset(&authctxt, 0, sizeof(authctxt));
388 pubkey_prepare(&authctxt);
389 authctxt.server_user = server_user;
390 authctxt.local_user = local_user;
391 authctxt.host = host;
392 authctxt.service = "ssh-connection"; /* service name */
393 authctxt.success = 0;
394 authctxt.method = authmethod_lookup("none");
395 authctxt.authlist = NULL;
396 authctxt.methoddata = NULL;
397 authctxt.sensitive = sensitive;
398 authctxt.info_req_seen = 0;
399 if (authctxt.method == NULL)
400 fatal("ssh_userauth2: internal error: cannot send userauth none request");
401
402 /* initial userauth request */
403 userauth_none(&authctxt);
404
405 dispatch_init(&input_userauth_error);
406 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
407 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
408 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
409 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */
410
411 pubkey_cleanup(&authctxt);
412 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
413
414 debug("Authentication succeeded (%s).", authctxt.method->name);
415 }
416
417 void
userauth(Authctxt * authctxt,char * authlist)418 userauth(Authctxt *authctxt, char *authlist)
419 {
420 if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
421 authctxt->method->cleanup(authctxt);
422
423 free(authctxt->methoddata);
424 authctxt->methoddata = NULL;
425 if (authlist == NULL) {
426 authlist = authctxt->authlist;
427 } else {
428 free(authctxt->authlist);
429 authctxt->authlist = authlist;
430 }
431 for (;;) {
432 Authmethod *method = authmethod_get(authlist);
433 if (method == NULL)
434 fatal("Permission denied (%s).", authlist);
435 authctxt->method = method;
436
437 /* reset the per method handler */
438 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
439 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
440
441 /* and try new method */
442 if (method->userauth(authctxt) != 0) {
443 debug2("we sent a %s packet, wait for reply", method->name);
444 break;
445 } else {
446 debug2("we did not send a packet, disable method");
447 method->enabled = NULL;
448 }
449 }
450 }
451
452 /* ARGSUSED */
453 void
input_userauth_error(int type,u_int32_t seq,void * ctxt)454 input_userauth_error(int type, u_int32_t seq, void *ctxt)
455 {
456 fatal("input_userauth_error: bad message during authentication: "
457 "type %d", type);
458 }
459
460 /* ARGSUSED */
461 void
input_userauth_banner(int type,u_int32_t seq,void * ctxt)462 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
463 {
464 char *msg, *raw, *lang;
465 u_int len;
466
467 debug3("input_userauth_banner");
468 raw = packet_get_string(&len);
469 lang = packet_get_string(NULL);
470 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
471 if (len > 65536)
472 len = 65536;
473 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
474 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
475 fprintf(stderr, "%s", msg);
476 free(msg);
477 }
478 free(raw);
479 free(lang);
480 }
481
482 /* ARGSUSED */
483 void
input_userauth_success(int type,u_int32_t seq,void * ctxt)484 input_userauth_success(int type, u_int32_t seq, void *ctxt)
485 {
486 Authctxt *authctxt = ctxt;
487
488 if (authctxt == NULL)
489 fatal("input_userauth_success: no authentication context");
490 free(authctxt->authlist);
491 authctxt->authlist = NULL;
492 if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
493 authctxt->method->cleanup(authctxt);
494 free(authctxt->methoddata);
495 authctxt->methoddata = NULL;
496 authctxt->success = 1; /* break out */
497 }
498
499 void
input_userauth_success_unexpected(int type,u_int32_t seq,void * ctxt)500 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
501 {
502 Authctxt *authctxt = ctxt;
503
504 if (authctxt == NULL)
505 fatal("%s: no authentication context", __func__);
506
507 fatal("Unexpected authentication success during %s.",
508 authctxt->method->name);
509 }
510
511 /* ARGSUSED */
512 void
input_userauth_failure(int type,u_int32_t seq,void * ctxt)513 input_userauth_failure(int type, u_int32_t seq, void *ctxt)
514 {
515 Authctxt *authctxt = ctxt;
516 char *authlist = NULL;
517 int partial;
518
519 if (authctxt == NULL)
520 fatal("input_userauth_failure: no authentication context");
521
522 authlist = packet_get_string(NULL);
523 partial = packet_get_char();
524 packet_check_eom();
525
526 if (partial != 0) {
527 logit("Authenticated with partial success.");
528 /* reset state */
529 pubkey_cleanup(authctxt);
530 pubkey_prepare(authctxt);
531 }
532 debug("Authentications that can continue: %s", authlist);
533
534 userauth(authctxt, authlist);
535 }
536
537 /* ARGSUSED */
538 void
input_userauth_pk_ok(int type,u_int32_t seq,void * ctxt)539 input_userauth_pk_ok(int type, u_int32_t seq, void *ctxt)
540 {
541 Authctxt *authctxt = ctxt;
542 Key *key = NULL;
543 Identity *id = NULL;
544 Buffer b;
545 int pktype, sent = 0;
546 u_int alen, blen;
547 char *pkalg, *fp;
548 u_char *pkblob;
549
550 if (authctxt == NULL)
551 fatal("input_userauth_pk_ok: no authentication context");
552 if (datafellows & SSH_BUG_PKOK) {
553 /* this is similar to SSH_BUG_PKAUTH */
554 debug2("input_userauth_pk_ok: SSH_BUG_PKOK");
555 pkblob = packet_get_string(&blen);
556 buffer_init(&b);
557 buffer_append(&b, pkblob, blen);
558 pkalg = buffer_get_string(&b, &alen);
559 buffer_free(&b);
560 } else {
561 pkalg = packet_get_string(&alen);
562 pkblob = packet_get_string(&blen);
563 }
564 packet_check_eom();
565
566 debug("Server accepts key: pkalg %s blen %u", pkalg, blen);
567
568 if ((pktype = key_type_from_name(pkalg)) == KEY_UNSPEC) {
569 debug("unknown pkalg %s", pkalg);
570 goto done;
571 }
572 if ((key = key_from_blob(pkblob, blen)) == NULL) {
573 debug("no key from blob. pkalg %s", pkalg);
574 goto done;
575 }
576 if (key->type != pktype) {
577 error("input_userauth_pk_ok: type mismatch "
578 "for decoded key (received %d, expected %d)",
579 key->type, pktype);
580 goto done;
581 }
582 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
583 debug2("input_userauth_pk_ok: fp %s", fp);
584 free(fp);
585
586 /*
587 * search keys in the reverse order, because last candidate has been
588 * moved to the end of the queue. this also avoids confusion by
589 * duplicate keys
590 */
591 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
592 if (key_equal(key, id->key)) {
593 sent = sign_and_send_pubkey(authctxt, id);
594 break;
595 }
596 }
597 done:
598 if (key != NULL)
599 key_free(key);
600 free(pkalg);
601 free(pkblob);
602
603 /* try another method if we did not send a packet */
604 if (sent == 0)
605 userauth(authctxt, NULL);
606 }
607
608 #ifdef GSSAPI
609 int
userauth_gssapi(Authctxt * authctxt)610 userauth_gssapi(Authctxt *authctxt)
611 {
612 Gssctxt *gssctxt = NULL;
613 static gss_OID_set gss_supported = NULL;
614 static u_int mech = 0;
615 OM_uint32 min;
616 int ok = 0;
617
618 /* Try one GSSAPI method at a time, rather than sending them all at
619 * once. */
620
621 if (gss_supported == NULL)
622 gss_indicate_mechs(&min, &gss_supported);
623
624 /* Check to see if the mechanism is usable before we offer it */
625 while (mech < gss_supported->count && !ok) {
626 /* My DER encoding requires length<128 */
627 if (gss_supported->elements[mech].length < 128 &&
628 ssh_gssapi_check_mechanism(&gssctxt,
629 &gss_supported->elements[mech], authctxt->host)) {
630 ok = 1; /* Mechanism works */
631 } else {
632 mech++;
633 }
634 }
635
636 if (!ok)
637 return 0;
638
639 authctxt->methoddata=(void *)gssctxt;
640
641 packet_start(SSH2_MSG_USERAUTH_REQUEST);
642 packet_put_cstring(authctxt->server_user);
643 packet_put_cstring(authctxt->service);
644 packet_put_cstring(authctxt->method->name);
645
646 packet_put_int(1);
647
648 packet_put_int((gss_supported->elements[mech].length) + 2);
649 packet_put_char(SSH_GSS_OIDTYPE);
650 packet_put_char(gss_supported->elements[mech].length);
651 packet_put_raw(gss_supported->elements[mech].elements,
652 gss_supported->elements[mech].length);
653
654 packet_send();
655
656 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
657 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
658 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
659 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
660
661 mech++; /* Move along to next candidate */
662
663 return 1;
664 }
665
666 static OM_uint32
process_gssapi_token(void * ctxt,gss_buffer_t recv_tok)667 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
668 {
669 Authctxt *authctxt = ctxt;
670 Gssctxt *gssctxt = authctxt->methoddata;
671 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
672 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
673 gss_buffer_desc gssbuf;
674 OM_uint32 status, ms, flags;
675 Buffer b;
676
677 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
678 recv_tok, &send_tok, &flags);
679
680 if (send_tok.length > 0) {
681 if (GSS_ERROR(status))
682 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
683 else
684 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
685
686 packet_put_string(send_tok.value, send_tok.length);
687 packet_send();
688 gss_release_buffer(&ms, &send_tok);
689 }
690
691 if (status == GSS_S_COMPLETE) {
692 /* send either complete or MIC, depending on mechanism */
693 if (!(flags & GSS_C_INTEG_FLAG)) {
694 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
695 packet_send();
696 } else {
697 ssh_gssapi_buildmic(&b, authctxt->server_user,
698 authctxt->service, "gssapi-with-mic");
699
700 gssbuf.value = buffer_ptr(&b);
701 gssbuf.length = buffer_len(&b);
702
703 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
704
705 if (!GSS_ERROR(status)) {
706 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
707 packet_put_string(mic.value, mic.length);
708
709 packet_send();
710 }
711
712 buffer_free(&b);
713 gss_release_buffer(&ms, &mic);
714 }
715 }
716
717 return status;
718 }
719
720 /* ARGSUSED */
721 void
input_gssapi_response(int type,u_int32_t plen,void * ctxt)722 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
723 {
724 Authctxt *authctxt = ctxt;
725 Gssctxt *gssctxt;
726 int oidlen;
727 char *oidv;
728
729 if (authctxt == NULL)
730 fatal("input_gssapi_response: no authentication context");
731 gssctxt = authctxt->methoddata;
732
733 /* Setup our OID */
734 oidv = packet_get_string(&oidlen);
735
736 if (oidlen <= 2 ||
737 oidv[0] != SSH_GSS_OIDTYPE ||
738 oidv[1] != oidlen - 2) {
739 free(oidv);
740 debug("Badly encoded mechanism OID received");
741 userauth(authctxt, NULL);
742 return;
743 }
744
745 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
746 fatal("Server returned different OID than expected");
747
748 packet_check_eom();
749
750 free(oidv);
751
752 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
753 /* Start again with next method on list */
754 debug("Trying to start again");
755 userauth(authctxt, NULL);
756 return;
757 }
758 }
759
760 /* ARGSUSED */
761 void
input_gssapi_token(int type,u_int32_t plen,void * ctxt)762 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
763 {
764 Authctxt *authctxt = ctxt;
765 gss_buffer_desc recv_tok;
766 OM_uint32 status;
767 u_int slen;
768
769 if (authctxt == NULL)
770 fatal("input_gssapi_response: no authentication context");
771
772 recv_tok.value = packet_get_string(&slen);
773 recv_tok.length = slen; /* safe typecast */
774
775 packet_check_eom();
776
777 status = process_gssapi_token(ctxt, &recv_tok);
778
779 free(recv_tok.value);
780
781 if (GSS_ERROR(status)) {
782 /* Start again with the next method in the list */
783 userauth(authctxt, NULL);
784 return;
785 }
786 }
787
788 /* ARGSUSED */
789 void
input_gssapi_errtok(int type,u_int32_t plen,void * ctxt)790 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
791 {
792 Authctxt *authctxt = ctxt;
793 Gssctxt *gssctxt;
794 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
795 gss_buffer_desc recv_tok;
796 OM_uint32 ms;
797 u_int len;
798
799 if (authctxt == NULL)
800 fatal("input_gssapi_response: no authentication context");
801 gssctxt = authctxt->methoddata;
802
803 recv_tok.value = packet_get_string(&len);
804 recv_tok.length = len;
805
806 packet_check_eom();
807
808 /* Stick it into GSSAPI and see what it says */
809 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
810 &recv_tok, &send_tok, NULL);
811
812 free(recv_tok.value);
813 gss_release_buffer(&ms, &send_tok);
814
815 /* Server will be returning a failed packet after this one */
816 }
817
818 /* ARGSUSED */
819 void
input_gssapi_error(int type,u_int32_t plen,void * ctxt)820 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
821 {
822 char *msg;
823 char *lang;
824
825 /* maj */(void)packet_get_int();
826 /* min */(void)packet_get_int();
827 msg=packet_get_string(NULL);
828 lang=packet_get_string(NULL);
829
830 packet_check_eom();
831
832 debug("Server GSSAPI Error:\n%s", msg);
833 free(msg);
834 free(lang);
835 }
836 #endif /* GSSAPI */
837
838 int
userauth_none(Authctxt * authctxt)839 userauth_none(Authctxt *authctxt)
840 {
841 /* initial userauth request */
842 packet_start(SSH2_MSG_USERAUTH_REQUEST);
843 packet_put_cstring(authctxt->server_user);
844 packet_put_cstring(authctxt->service);
845 packet_put_cstring(authctxt->method->name);
846 packet_send();
847 return 1;
848 }
849
850 int
userauth_passwd(Authctxt * authctxt)851 userauth_passwd(Authctxt *authctxt)
852 {
853 static int attempt = 0;
854 char prompt[150];
855 char *password;
856 const char *host = options.host_key_alias ? options.host_key_alias :
857 authctxt->host;
858
859 if (attempt++ >= options.number_of_password_prompts)
860 return 0;
861
862 if (attempt != 1)
863 error("Permission denied, please try again.");
864
865 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
866 authctxt->server_user, host);
867 password = read_passphrase(prompt, 0);
868 packet_start(SSH2_MSG_USERAUTH_REQUEST);
869 packet_put_cstring(authctxt->server_user);
870 packet_put_cstring(authctxt->service);
871 packet_put_cstring(authctxt->method->name);
872 packet_put_char(0);
873 packet_put_cstring(password);
874 explicit_bzero(password, strlen(password));
875 free(password);
876 packet_add_padding(64);
877 packet_send();
878
879 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
880 &input_userauth_passwd_changereq);
881
882 return 1;
883 }
884
885 /*
886 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
887 */
888 /* ARGSUSED */
889 void
input_userauth_passwd_changereq(int type,u_int32_t seqnr,void * ctxt)890 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
891 {
892 Authctxt *authctxt = ctxt;
893 char *info, *lang, *password = NULL, *retype = NULL;
894 char prompt[150];
895 const char *host = options.host_key_alias ? options.host_key_alias :
896 authctxt->host;
897
898 debug2("input_userauth_passwd_changereq");
899
900 if (authctxt == NULL)
901 fatal("input_userauth_passwd_changereq: "
902 "no authentication context");
903
904 info = packet_get_string(NULL);
905 lang = packet_get_string(NULL);
906 if (strlen(info) > 0)
907 logit("%s", info);
908 free(info);
909 free(lang);
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(1); /* additional info */
915 snprintf(prompt, sizeof(prompt),
916 "Enter %.30s@%.128s's old password: ",
917 authctxt->server_user, host);
918 password = read_passphrase(prompt, 0);
919 packet_put_cstring(password);
920 explicit_bzero(password, strlen(password));
921 free(password);
922 password = NULL;
923 while (password == NULL) {
924 snprintf(prompt, sizeof(prompt),
925 "Enter %.30s@%.128s's new password: ",
926 authctxt->server_user, host);
927 password = read_passphrase(prompt, RP_ALLOW_EOF);
928 if (password == NULL) {
929 /* bail out */
930 return;
931 }
932 snprintf(prompt, sizeof(prompt),
933 "Retype %.30s@%.128s's new password: ",
934 authctxt->server_user, host);
935 retype = read_passphrase(prompt, 0);
936 if (strcmp(password, retype) != 0) {
937 explicit_bzero(password, strlen(password));
938 free(password);
939 logit("Mismatch; try again, EOF to quit.");
940 password = NULL;
941 }
942 explicit_bzero(retype, strlen(retype));
943 free(retype);
944 }
945 packet_put_cstring(password);
946 explicit_bzero(password, strlen(password));
947 free(password);
948 packet_add_padding(64);
949 packet_send();
950
951 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
952 &input_userauth_passwd_changereq);
953 }
954
955 static int
identity_sign(Identity * id,u_char ** sigp,u_int * lenp,u_char * data,u_int datalen)956 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
957 u_char *data, u_int datalen)
958 {
959 Key *prv;
960 int ret;
961
962 /* the agent supports this key */
963 if (id->ac)
964 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
965 data, datalen));
966 /*
967 * we have already loaded the private key or
968 * the private key is stored in external hardware
969 */
970 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
971 return (key_sign(id->key, sigp, lenp, data, datalen));
972 /* load the private key from the file */
973 if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL)
974 return (-1);
975 ret = key_sign(prv, sigp, lenp, data, datalen);
976 key_free(prv);
977 return (ret);
978 }
979
980 static int
sign_and_send_pubkey(Authctxt * authctxt,Identity * id)981 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
982 {
983 Buffer b;
984 u_char *blob, *signature;
985 u_int bloblen, slen;
986 u_int skip = 0;
987 int ret = -1;
988 int have_sig = 1;
989 char *fp;
990
991 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
992 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp);
993 free(fp);
994
995 if (key_to_blob(id->key, &blob, &bloblen) == 0) {
996 /* we cannot handle this key */
997 debug3("sign_and_send_pubkey: cannot handle key");
998 return 0;
999 }
1000 /* data to be signed */
1001 buffer_init(&b);
1002 if (datafellows & SSH_OLD_SESSIONID) {
1003 buffer_append(&b, session_id2, session_id2_len);
1004 skip = session_id2_len;
1005 } else {
1006 buffer_put_string(&b, session_id2, session_id2_len);
1007 skip = buffer_len(&b);
1008 }
1009 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1010 buffer_put_cstring(&b, authctxt->server_user);
1011 buffer_put_cstring(&b,
1012 datafellows & SSH_BUG_PKSERVICE ?
1013 "ssh-userauth" :
1014 authctxt->service);
1015 if (datafellows & SSH_BUG_PKAUTH) {
1016 buffer_put_char(&b, have_sig);
1017 } else {
1018 buffer_put_cstring(&b, authctxt->method->name);
1019 buffer_put_char(&b, have_sig);
1020 buffer_put_cstring(&b, key_ssh_name(id->key));
1021 }
1022 buffer_put_string(&b, blob, bloblen);
1023
1024 /* generate signature */
1025 ret = identity_sign(id, &signature, &slen,
1026 buffer_ptr(&b), buffer_len(&b));
1027 if (ret == -1) {
1028 free(blob);
1029 buffer_free(&b);
1030 return 0;
1031 }
1032 #ifdef DEBUG_PK
1033 buffer_dump(&b);
1034 #endif
1035 if (datafellows & SSH_BUG_PKSERVICE) {
1036 buffer_clear(&b);
1037 buffer_append(&b, session_id2, session_id2_len);
1038 skip = session_id2_len;
1039 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1040 buffer_put_cstring(&b, authctxt->server_user);
1041 buffer_put_cstring(&b, authctxt->service);
1042 buffer_put_cstring(&b, authctxt->method->name);
1043 buffer_put_char(&b, have_sig);
1044 if (!(datafellows & SSH_BUG_PKAUTH))
1045 buffer_put_cstring(&b, key_ssh_name(id->key));
1046 buffer_put_string(&b, blob, bloblen);
1047 }
1048 free(blob);
1049
1050 /* append signature */
1051 buffer_put_string(&b, signature, slen);
1052 free(signature);
1053
1054 /* skip session id and packet type */
1055 if (buffer_len(&b) < skip + 1)
1056 fatal("userauth_pubkey: internal error");
1057 buffer_consume(&b, skip + 1);
1058
1059 /* put remaining data from buffer into packet */
1060 packet_start(SSH2_MSG_USERAUTH_REQUEST);
1061 packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1062 buffer_free(&b);
1063 packet_send();
1064
1065 return 1;
1066 }
1067
1068 static int
send_pubkey_test(Authctxt * authctxt,Identity * id)1069 send_pubkey_test(Authctxt *authctxt, Identity *id)
1070 {
1071 u_char *blob;
1072 u_int bloblen, have_sig = 0;
1073
1074 debug3("send_pubkey_test");
1075
1076 if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1077 /* we cannot handle this key */
1078 debug3("send_pubkey_test: cannot handle key");
1079 return 0;
1080 }
1081 /* register callback for USERAUTH_PK_OK message */
1082 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1083
1084 packet_start(SSH2_MSG_USERAUTH_REQUEST);
1085 packet_put_cstring(authctxt->server_user);
1086 packet_put_cstring(authctxt->service);
1087 packet_put_cstring(authctxt->method->name);
1088 packet_put_char(have_sig);
1089 if (!(datafellows & SSH_BUG_PKAUTH))
1090 packet_put_cstring(key_ssh_name(id->key));
1091 packet_put_string(blob, bloblen);
1092 free(blob);
1093 packet_send();
1094 return 1;
1095 }
1096
1097 static Key *
load_identity_file(char * filename,int userprovided)1098 load_identity_file(char *filename, int userprovided)
1099 {
1100 Key *private;
1101 char prompt[300], *passphrase;
1102 int perm_ok = 0, quit, i;
1103 struct stat st;
1104
1105 if (stat(filename, &st) < 0) {
1106 (userprovided ? logit : debug3)("no such identity: %s: %s",
1107 filename, strerror(errno));
1108 return NULL;
1109 }
1110 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1111 if (!perm_ok) {
1112 if (private != NULL)
1113 key_free(private);
1114 return NULL;
1115 }
1116 if (private == NULL) {
1117 if (options.batch_mode)
1118 return NULL;
1119 snprintf(prompt, sizeof prompt,
1120 "Enter passphrase for key '%.100s': ", filename);
1121 for (i = 0; i < options.number_of_password_prompts; i++) {
1122 passphrase = read_passphrase(prompt, 0);
1123 if (strcmp(passphrase, "") != 0) {
1124 private = key_load_private_type(KEY_UNSPEC,
1125 filename, passphrase, NULL, NULL);
1126 quit = 0;
1127 } else {
1128 debug2("no passphrase given, try next key");
1129 quit = 1;
1130 }
1131 explicit_bzero(passphrase, strlen(passphrase));
1132 free(passphrase);
1133 if (private != NULL || quit)
1134 break;
1135 debug2("bad passphrase given, try again...");
1136 }
1137 }
1138 return private;
1139 }
1140
1141 /*
1142 * try keys in the following order:
1143 * 1. agent keys that are found in the config file
1144 * 2. other agent keys
1145 * 3. keys that are only listed in the config file
1146 */
1147 static void
pubkey_prepare(Authctxt * authctxt)1148 pubkey_prepare(Authctxt *authctxt)
1149 {
1150 Identity *id, *id2, *tmp;
1151 Idlist agent, files, *preferred;
1152 Key *key;
1153 AuthenticationConnection *ac;
1154 char *comment;
1155 int i, found;
1156
1157 TAILQ_INIT(&agent); /* keys from the agent */
1158 TAILQ_INIT(&files); /* keys from the config file */
1159 preferred = &authctxt->keys;
1160 TAILQ_INIT(preferred); /* preferred order of keys */
1161
1162 /* list of keys stored in the filesystem and PKCS#11 */
1163 for (i = 0; i < options.num_identity_files; i++) {
1164 key = options.identity_keys[i];
1165 if (key && key->type == KEY_RSA1)
1166 continue;
1167 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1168 continue;
1169 options.identity_keys[i] = NULL;
1170 id = xcalloc(1, sizeof(*id));
1171 id->key = key;
1172 id->filename = xstrdup(options.identity_files[i]);
1173 id->userprovided = options.identity_file_userprovided[i];
1174 TAILQ_INSERT_TAIL(&files, id, next);
1175 }
1176 /* Prefer PKCS11 keys that are explicitly listed */
1177 TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1178 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0)
1179 continue;
1180 found = 0;
1181 TAILQ_FOREACH(id2, &files, next) {
1182 if (id2->key == NULL ||
1183 (id2->key->flags & KEY_FLAG_EXT) != 0)
1184 continue;
1185 if (key_equal(id->key, id2->key)) {
1186 TAILQ_REMOVE(&files, id, next);
1187 TAILQ_INSERT_TAIL(preferred, id, next);
1188 found = 1;
1189 break;
1190 }
1191 }
1192 /* If IdentitiesOnly set and key not found then don't use it */
1193 if (!found && options.identities_only) {
1194 TAILQ_REMOVE(&files, id, next);
1195 explicit_bzero(id, sizeof(*id));
1196 free(id);
1197 }
1198 }
1199 /* list of keys supported by the agent */
1200 if ((ac = ssh_get_authentication_connection())) {
1201 for (key = ssh_get_first_identity(ac, &comment, 2);
1202 key != NULL;
1203 key = ssh_get_next_identity(ac, &comment, 2)) {
1204 found = 0;
1205 TAILQ_FOREACH(id, &files, next) {
1206 /* agent keys from the config file are preferred */
1207 if (key_equal(key, id->key)) {
1208 key_free(key);
1209 free(comment);
1210 TAILQ_REMOVE(&files, id, next);
1211 TAILQ_INSERT_TAIL(preferred, id, next);
1212 id->ac = ac;
1213 found = 1;
1214 break;
1215 }
1216 }
1217 if (!found && !options.identities_only) {
1218 id = xcalloc(1, sizeof(*id));
1219 id->key = key;
1220 id->filename = comment;
1221 id->ac = ac;
1222 TAILQ_INSERT_TAIL(&agent, id, next);
1223 }
1224 }
1225 /* append remaining agent keys */
1226 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1227 TAILQ_REMOVE(&agent, id, next);
1228 TAILQ_INSERT_TAIL(preferred, id, next);
1229 }
1230 authctxt->agent = ac;
1231 }
1232 /* append remaining keys from the config file */
1233 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1234 TAILQ_REMOVE(&files, id, next);
1235 TAILQ_INSERT_TAIL(preferred, id, next);
1236 }
1237 TAILQ_FOREACH(id, preferred, next) {
1238 debug2("key: %s (%p),%s", id->filename, id->key,
1239 id->userprovided ? " explicit" : "");
1240 }
1241 }
1242
1243 static void
pubkey_cleanup(Authctxt * authctxt)1244 pubkey_cleanup(Authctxt *authctxt)
1245 {
1246 Identity *id;
1247
1248 if (authctxt->agent != NULL)
1249 ssh_close_authentication_connection(authctxt->agent);
1250 for (id = TAILQ_FIRST(&authctxt->keys); id;
1251 id = TAILQ_FIRST(&authctxt->keys)) {
1252 TAILQ_REMOVE(&authctxt->keys, id, next);
1253 if (id->key)
1254 key_free(id->key);
1255 free(id->filename);
1256 free(id);
1257 }
1258 }
1259
1260 int
userauth_pubkey(Authctxt * authctxt)1261 userauth_pubkey(Authctxt *authctxt)
1262 {
1263 Identity *id;
1264 int sent = 0;
1265
1266 while ((id = TAILQ_FIRST(&authctxt->keys))) {
1267 if (id->tried++)
1268 return (0);
1269 /* move key to the end of the queue */
1270 TAILQ_REMOVE(&authctxt->keys, id, next);
1271 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1272 /*
1273 * send a test message if we have the public key. for
1274 * encrypted keys we cannot do this and have to load the
1275 * private key instead
1276 */
1277 if (id->key != NULL) {
1278 if (key_type_plain(id->key->type) == KEY_RSA &&
1279 (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1280 debug("Skipped %s key %s for RSA/MD5 server",
1281 key_type(id->key), id->filename);
1282 } else if (id->key->type != KEY_RSA1) {
1283 debug("Offering %s public key: %s",
1284 key_type(id->key), id->filename);
1285 sent = send_pubkey_test(authctxt, id);
1286 }
1287 } else {
1288 debug("Trying private key: %s", id->filename);
1289 id->key = load_identity_file(id->filename,
1290 id->userprovided);
1291 if (id->key != NULL) {
1292 id->isprivate = 1;
1293 if (key_type_plain(id->key->type) == KEY_RSA &&
1294 (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1295 debug("Skipped %s key %s for RSA/MD5 "
1296 "server", key_type(id->key),
1297 id->filename);
1298 } else {
1299 sent = sign_and_send_pubkey(
1300 authctxt, id);
1301 }
1302 key_free(id->key);
1303 id->key = NULL;
1304 }
1305 }
1306 if (sent)
1307 return (sent);
1308 }
1309 return (0);
1310 }
1311
1312 /*
1313 * Send userauth request message specifying keyboard-interactive method.
1314 */
1315 int
userauth_kbdint(Authctxt * authctxt)1316 userauth_kbdint(Authctxt *authctxt)
1317 {
1318 static int attempt = 0;
1319
1320 if (attempt++ >= options.number_of_password_prompts)
1321 return 0;
1322 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1323 if (attempt > 1 && !authctxt->info_req_seen) {
1324 debug3("userauth_kbdint: disable: no info_req_seen");
1325 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1326 return 0;
1327 }
1328
1329 debug2("userauth_kbdint");
1330 packet_start(SSH2_MSG_USERAUTH_REQUEST);
1331 packet_put_cstring(authctxt->server_user);
1332 packet_put_cstring(authctxt->service);
1333 packet_put_cstring(authctxt->method->name);
1334 packet_put_cstring(""); /* lang */
1335 packet_put_cstring(options.kbd_interactive_devices ?
1336 options.kbd_interactive_devices : "");
1337 packet_send();
1338
1339 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1340 return 1;
1341 }
1342
1343 /*
1344 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1345 */
1346 void
input_userauth_info_req(int type,u_int32_t seq,void * ctxt)1347 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1348 {
1349 Authctxt *authctxt = ctxt;
1350 char *name, *inst, *lang, *prompt, *response;
1351 u_int num_prompts, i;
1352 int echo = 0;
1353
1354 debug2("input_userauth_info_req");
1355
1356 if (authctxt == NULL)
1357 fatal("input_userauth_info_req: no authentication context");
1358
1359 authctxt->info_req_seen = 1;
1360
1361 name = packet_get_string(NULL);
1362 inst = packet_get_string(NULL);
1363 lang = packet_get_string(NULL);
1364 if (strlen(name) > 0)
1365 logit("%s", name);
1366 if (strlen(inst) > 0)
1367 logit("%s", inst);
1368 free(name);
1369 free(inst);
1370 free(lang);
1371
1372 num_prompts = packet_get_int();
1373 /*
1374 * Begin to build info response packet based on prompts requested.
1375 * We commit to providing the correct number of responses, so if
1376 * further on we run into a problem that prevents this, we have to
1377 * be sure and clean this up and send a correct error response.
1378 */
1379 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1380 packet_put_int(num_prompts);
1381
1382 debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1383 for (i = 0; i < num_prompts; i++) {
1384 prompt = packet_get_string(NULL);
1385 echo = packet_get_char();
1386
1387 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1388
1389 packet_put_cstring(response);
1390 explicit_bzero(response, strlen(response));
1391 free(response);
1392 free(prompt);
1393 }
1394 packet_check_eom(); /* done with parsing incoming message. */
1395
1396 packet_add_padding(64);
1397 packet_send();
1398 }
1399
1400 static int
ssh_keysign(Key * key,u_char ** sigp,u_int * lenp,u_char * data,u_int datalen)1401 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1402 u_char *data, u_int datalen)
1403 {
1404 Buffer b;
1405 struct stat st;
1406 pid_t pid;
1407 int to[2], from[2], status, version = 2;
1408
1409 debug2("ssh_keysign called");
1410
1411 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1412 error("ssh_keysign: not installed: %s", strerror(errno));
1413 return -1;
1414 }
1415 if (fflush(stdout) != 0)
1416 error("ssh_keysign: fflush: %s", strerror(errno));
1417 if (pipe(to) < 0) {
1418 error("ssh_keysign: pipe: %s", strerror(errno));
1419 return -1;
1420 }
1421 if (pipe(from) < 0) {
1422 error("ssh_keysign: pipe: %s", strerror(errno));
1423 return -1;
1424 }
1425 if ((pid = fork()) < 0) {
1426 error("ssh_keysign: fork: %s", strerror(errno));
1427 return -1;
1428 }
1429 if (pid == 0) {
1430 /* keep the socket on exec */
1431 fcntl(packet_get_connection_in(), F_SETFD, 0);
1432 permanently_drop_suid(getuid());
1433 close(from[0]);
1434 if (dup2(from[1], STDOUT_FILENO) < 0)
1435 fatal("ssh_keysign: dup2: %s", strerror(errno));
1436 close(to[1]);
1437 if (dup2(to[0], STDIN_FILENO) < 0)
1438 fatal("ssh_keysign: dup2: %s", strerror(errno));
1439 close(from[1]);
1440 close(to[0]);
1441 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1442 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1443 strerror(errno));
1444 }
1445 close(from[1]);
1446 close(to[0]);
1447
1448 buffer_init(&b);
1449 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1450 buffer_put_string(&b, data, datalen);
1451 if (ssh_msg_send(to[1], version, &b) == -1)
1452 fatal("ssh_keysign: couldn't send request");
1453
1454 if (ssh_msg_recv(from[0], &b) < 0) {
1455 error("ssh_keysign: no reply");
1456 buffer_free(&b);
1457 return -1;
1458 }
1459 close(from[0]);
1460 close(to[1]);
1461
1462 while (waitpid(pid, &status, 0) < 0)
1463 if (errno != EINTR)
1464 break;
1465
1466 if (buffer_get_char(&b) != version) {
1467 error("ssh_keysign: bad version");
1468 buffer_free(&b);
1469 return -1;
1470 }
1471 *sigp = buffer_get_string(&b, lenp);
1472 buffer_free(&b);
1473
1474 return 0;
1475 }
1476
1477 int
userauth_hostbased(Authctxt * authctxt)1478 userauth_hostbased(Authctxt *authctxt)
1479 {
1480 Key *private = NULL;
1481 Sensitive *sensitive = authctxt->sensitive;
1482 Buffer b;
1483 u_char *signature, *blob;
1484 char *chost, *pkalg, *p;
1485 const char *service;
1486 u_int blen, slen;
1487 int ok, i, found = 0;
1488
1489 /* check for a useful key */
1490 for (i = 0; i < sensitive->nkeys; i++) {
1491 private = sensitive->keys[i];
1492 if (private && private->type != KEY_RSA1) {
1493 found = 1;
1494 /* we take and free the key */
1495 sensitive->keys[i] = NULL;
1496 break;
1497 }
1498 }
1499 if (!found) {
1500 debug("No more client hostkeys for hostbased authentication.");
1501 return 0;
1502 }
1503 if (key_to_blob(private, &blob, &blen) == 0) {
1504 key_free(private);
1505 return 0;
1506 }
1507 /* figure out a name for the client host */
1508 p = get_local_name(packet_get_connection_in());
1509 if (p == NULL) {
1510 error("userauth_hostbased: cannot get local ipaddr/name");
1511 key_free(private);
1512 free(blob);
1513 return 0;
1514 }
1515 xasprintf(&chost, "%s.", p);
1516 debug2("userauth_hostbased: chost %s", chost);
1517 free(p);
1518
1519 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1520 authctxt->service;
1521 pkalg = xstrdup(key_ssh_name(private));
1522 buffer_init(&b);
1523 /* construct data */
1524 buffer_put_string(&b, session_id2, session_id2_len);
1525 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1526 buffer_put_cstring(&b, authctxt->server_user);
1527 buffer_put_cstring(&b, service);
1528 buffer_put_cstring(&b, authctxt->method->name);
1529 buffer_put_cstring(&b, pkalg);
1530 buffer_put_string(&b, blob, blen);
1531 buffer_put_cstring(&b, chost);
1532 buffer_put_cstring(&b, authctxt->local_user);
1533 #ifdef DEBUG_PK
1534 buffer_dump(&b);
1535 #endif
1536 if (sensitive->external_keysign)
1537 ok = ssh_keysign(private, &signature, &slen,
1538 buffer_ptr(&b), buffer_len(&b));
1539 else
1540 ok = key_sign(private, &signature, &slen,
1541 buffer_ptr(&b), buffer_len(&b));
1542 key_free(private);
1543 buffer_free(&b);
1544 if (ok != 0) {
1545 error("key_sign failed");
1546 free(chost);
1547 free(pkalg);
1548 free(blob);
1549 return 0;
1550 }
1551 packet_start(SSH2_MSG_USERAUTH_REQUEST);
1552 packet_put_cstring(authctxt->server_user);
1553 packet_put_cstring(authctxt->service);
1554 packet_put_cstring(authctxt->method->name);
1555 packet_put_cstring(pkalg);
1556 packet_put_string(blob, blen);
1557 packet_put_cstring(chost);
1558 packet_put_cstring(authctxt->local_user);
1559 packet_put_string(signature, slen);
1560 explicit_bzero(signature, slen);
1561 free(signature);
1562 free(chost);
1563 free(pkalg);
1564 free(blob);
1565
1566 packet_send();
1567 return 1;
1568 }
1569
1570 /* find auth method */
1571
1572 /*
1573 * given auth method name, if configurable options permit this method fill
1574 * in auth_ident field and return true, otherwise return false.
1575 */
1576 static int
authmethod_is_enabled(Authmethod * method)1577 authmethod_is_enabled(Authmethod *method)
1578 {
1579 if (method == NULL)
1580 return 0;
1581 /* return false if options indicate this method is disabled */
1582 if (method->enabled == NULL || *method->enabled == 0)
1583 return 0;
1584 /* return false if batch mode is enabled but method needs interactive mode */
1585 if (method->batch_flag != NULL && *method->batch_flag != 0)
1586 return 0;
1587 return 1;
1588 }
1589
1590 static Authmethod *
authmethod_lookup(const char * name)1591 authmethod_lookup(const char *name)
1592 {
1593 Authmethod *method = NULL;
1594 if (name != NULL)
1595 for (method = authmethods; method->name != NULL; method++)
1596 if (strcmp(name, method->name) == 0)
1597 return method;
1598 debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1599 return NULL;
1600 }
1601
1602 /* XXX internal state */
1603 static Authmethod *current = NULL;
1604 static char *supported = NULL;
1605 static char *preferred = NULL;
1606
1607 /*
1608 * Given the authentication method list sent by the server, return the
1609 * next method we should try. If the server initially sends a nil list,
1610 * use a built-in default list.
1611 */
1612 static Authmethod *
authmethod_get(char * authlist)1613 authmethod_get(char *authlist)
1614 {
1615 char *name = NULL;
1616 u_int next;
1617
1618 /* Use a suitable default if we're passed a nil list. */
1619 if (authlist == NULL || strlen(authlist) == 0)
1620 authlist = options.preferred_authentications;
1621
1622 if (supported == NULL || strcmp(authlist, supported) != 0) {
1623 debug3("start over, passed a different list %s", authlist);
1624 free(supported);
1625 supported = xstrdup(authlist);
1626 preferred = options.preferred_authentications;
1627 debug3("preferred %s", preferred);
1628 current = NULL;
1629 } else if (current != NULL && authmethod_is_enabled(current))
1630 return current;
1631
1632 for (;;) {
1633 if ((name = match_list(preferred, supported, &next)) == NULL) {
1634 debug("No more authentication methods to try.");
1635 current = NULL;
1636 return NULL;
1637 }
1638 preferred += next;
1639 debug3("authmethod_lookup %s", name);
1640 debug3("remaining preferred: %s", preferred);
1641 if ((current = authmethod_lookup(name)) != NULL &&
1642 authmethod_is_enabled(current)) {
1643 debug3("authmethod_is_enabled %s", name);
1644 debug("Next authentication method: %s", name);
1645 free(name);
1646 return current;
1647 }
1648 free(name);
1649 }
1650 }
1651
1652 static char *
authmethods_get(void)1653 authmethods_get(void)
1654 {
1655 Authmethod *method = NULL;
1656 Buffer b;
1657 char *list;
1658
1659 buffer_init(&b);
1660 for (method = authmethods; method->name != NULL; method++) {
1661 if (authmethod_is_enabled(method)) {
1662 if (buffer_len(&b) > 0)
1663 buffer_append(&b, ",", 1);
1664 buffer_append(&b, method->name, strlen(method->name));
1665 }
1666 }
1667 buffer_append(&b, "\0", 1);
1668 list = xstrdup(buffer_ptr(&b));
1669 buffer_free(&b);
1670 return list;
1671 }
1672
1673