1 /* $OpenBSD: sshconnect2.c,v 1.204 2014/02/02 03:44:32 djm Exp $ */
2 /* $FreeBSD: stable/9/crypto/openssh/sshconnect2.c 264693 2014-04-20 13:12:32Z des $ */
3 /*
4 * Copyright (c) 2000 Markus Friedl. All rights reserved.
5 * Copyright (c) 2008 Damien Miller. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include "includes.h"
29 __RCSID("$FreeBSD: stable/9/crypto/openssh/sshconnect2.c 264693 2014-04-20 13:12:32Z des $");
30
31 #include <sys/types.h>
32 #include <sys/socket.h>
33 #include <sys/wait.h>
34 #include <sys/stat.h>
35
36 #include <errno.h>
37 #include <fcntl.h>
38 #include <netdb.h>
39 #include <pwd.h>
40 #include <signal.h>
41 #include <stdarg.h>
42 #include <stdio.h>
43 #include <string.h>
44 #include <unistd.h>
45 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
46 #include <vis.h>
47 #endif
48
49 #include "openbsd-compat/sys-queue.h"
50
51 #include "xmalloc.h"
52 #include "ssh.h"
53 #include "ssh2.h"
54 #include "buffer.h"
55 #include "packet.h"
56 #include "compat.h"
57 #include "cipher.h"
58 #include "key.h"
59 #include "kex.h"
60 #include "myproposal.h"
61 #include "sshconnect.h"
62 #include "authfile.h"
63 #include "dh.h"
64 #include "authfd.h"
65 #include "log.h"
66 #include "readconf.h"
67 #include "misc.h"
68 #include "match.h"
69 #include "dispatch.h"
70 #include "canohost.h"
71 #include "msg.h"
72 #include "pathnames.h"
73 #include "uidswap.h"
74 #include "hostfile.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 #ifdef NONE_CIPHER_ENABLED
85 extern Kex *xxx_kex;
86
87 /*
88 * tty_flag is set in ssh.c so we can use it here. If set then prevent
89 * the switch to the null cipher.
90 */
91
92 extern int tty_flag;
93 #endif
94
95 /*
96 * SSH2 key exchange
97 */
98
99 u_char *session_id2 = NULL;
100 u_int session_id2_len = 0;
101
102 char *xxx_host;
103 struct sockaddr *xxx_hostaddr;
104
105 Kex *xxx_kex = NULL;
106
107 static int
verify_host_key_callback(Key * hostkey)108 verify_host_key_callback(Key *hostkey)
109 {
110 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey) == -1)
111 fatal("Host key verification failed.");
112 return 0;
113 }
114
115 static char *
order_hostkeyalgs(char * host,struct sockaddr * hostaddr,u_short port)116 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port)
117 {
118 char *oavail, *avail, *first, *last, *alg, *hostname, *ret;
119 size_t maxlen;
120 struct hostkeys *hostkeys;
121 int ktype;
122 u_int i;
123
124 /* Find all hostkeys for this hostname */
125 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
126 hostkeys = init_hostkeys();
127 for (i = 0; i < options.num_user_hostfiles; i++)
128 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i]);
129 for (i = 0; i < options.num_system_hostfiles; i++)
130 load_hostkeys(hostkeys, hostname, options.system_hostfiles[i]);
131
132 oavail = avail = xstrdup(KEX_DEFAULT_PK_ALG);
133 maxlen = strlen(avail) + 1;
134 first = xmalloc(maxlen);
135 last = xmalloc(maxlen);
136 *first = *last = '\0';
137
138 #define ALG_APPEND(to, from) \
139 do { \
140 if (*to != '\0') \
141 strlcat(to, ",", maxlen); \
142 strlcat(to, from, maxlen); \
143 } while (0)
144
145 while ((alg = strsep(&avail, ",")) && *alg != '\0') {
146 if ((ktype = key_type_from_name(alg)) == KEY_UNSPEC)
147 fatal("%s: unknown alg %s", __func__, alg);
148 if (lookup_key_in_hostkeys_by_type(hostkeys,
149 key_type_plain(ktype), NULL))
150 ALG_APPEND(first, alg);
151 else
152 ALG_APPEND(last, alg);
153 }
154 #undef ALG_APPEND
155 xasprintf(&ret, "%s%s%s", first, *first == '\0' ? "" : ",", last);
156 if (*first != '\0')
157 debug3("%s: prefer hostkeyalgs: %s", __func__, first);
158
159 free(first);
160 free(last);
161 free(hostname);
162 free(oavail);
163 free_hostkeys(hostkeys);
164
165 return ret;
166 }
167
168 void
ssh_kex2(char * host,struct sockaddr * hostaddr,u_short port)169 ssh_kex2(char *host, struct sockaddr *hostaddr, u_short port)
170 {
171 Kex *kex;
172
173 xxx_host = host;
174 xxx_hostaddr = hostaddr;
175
176 if (options.ciphers == (char *)-1) {
177 logit("No valid ciphers for protocol version 2 given, using defaults.");
178 options.ciphers = NULL;
179 }
180 if (options.ciphers != NULL) {
181 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
182 myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
183 }
184 myproposal[PROPOSAL_ENC_ALGS_CTOS] =
185 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
186 myproposal[PROPOSAL_ENC_ALGS_STOC] =
187 compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
188 if (options.compression) {
189 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
190 myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib@openssh.com,zlib,none";
191 } else {
192 myproposal[PROPOSAL_COMP_ALGS_CTOS] =
193 myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com,zlib";
194 }
195 if (options.macs != NULL) {
196 myproposal[PROPOSAL_MAC_ALGS_CTOS] =
197 myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
198 }
199 if (options.hostkeyalgorithms != NULL)
200 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
201 compat_pkalg_proposal(options.hostkeyalgorithms);
202 else {
203 /* Prefer algorithms that we already have keys for */
204 myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] =
205 compat_pkalg_proposal(
206 order_hostkeyalgs(host, hostaddr, port));
207 }
208 if (options.kex_algorithms != NULL)
209 myproposal[PROPOSAL_KEX_ALGS] = options.kex_algorithms;
210 myproposal[PROPOSAL_KEX_ALGS] = compat_kex_proposal(
211 myproposal[PROPOSAL_KEX_ALGS]);
212
213 if (options.rekey_limit || options.rekey_interval)
214 packet_set_rekey_limits((u_int32_t)options.rekey_limit,
215 (time_t)options.rekey_interval);
216
217 /* start key exchange */
218 kex = kex_setup(myproposal);
219 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_client;
220 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_client;
221 kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
222 kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
223 kex->kex[KEX_ECDH_SHA2] = kexecdh_client;
224 kex->kex[KEX_C25519_SHA256] = kexc25519_client;
225 kex->client_version_string=client_version_string;
226 kex->server_version_string=server_version_string;
227 kex->verify_host_key=&verify_host_key_callback;
228
229 xxx_kex = kex;
230
231 dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
232
233 if (options.use_roaming && !kex->roaming) {
234 debug("Roaming not allowed by server");
235 options.use_roaming = 0;
236 }
237
238 session_id2 = kex->session_id;
239 session_id2_len = kex->session_id_len;
240
241 #ifdef DEBUG_KEXDH
242 /* send 1st encrypted/maced/compressed message */
243 packet_start(SSH2_MSG_IGNORE);
244 packet_put_cstring("markus");
245 packet_send();
246 packet_write_wait();
247 #endif
248 }
249
250 /*
251 * Authenticate user
252 */
253
254 typedef struct Authctxt Authctxt;
255 typedef struct Authmethod Authmethod;
256 typedef struct identity Identity;
257 typedef struct idlist Idlist;
258
259 struct identity {
260 TAILQ_ENTRY(identity) next;
261 AuthenticationConnection *ac; /* set if agent supports key */
262 Key *key; /* public/private key */
263 char *filename; /* comment for agent-only keys */
264 int tried;
265 int isprivate; /* key points to the private key */
266 int userprovided;
267 };
268 TAILQ_HEAD(idlist, identity);
269
270 struct Authctxt {
271 const char *server_user;
272 const char *local_user;
273 const char *host;
274 const char *service;
275 Authmethod *method;
276 sig_atomic_t success;
277 char *authlist;
278 /* pubkey */
279 Idlist keys;
280 AuthenticationConnection *agent;
281 /* hostbased */
282 Sensitive *sensitive;
283 /* kbd-interactive */
284 int info_req_seen;
285 /* generic */
286 void *methoddata;
287 };
288 struct Authmethod {
289 char *name; /* string to compare against server's list */
290 int (*userauth)(Authctxt *authctxt);
291 void (*cleanup)(Authctxt *authctxt);
292 int *enabled; /* flag in option struct that enables method */
293 int *batch_flag; /* flag in option struct that disables method */
294 };
295
296 void input_userauth_success(int, u_int32_t, void *);
297 void input_userauth_success_unexpected(int, u_int32_t, void *);
298 void input_userauth_failure(int, u_int32_t, void *);
299 void input_userauth_banner(int, u_int32_t, void *);
300 void input_userauth_error(int, u_int32_t, void *);
301 void input_userauth_info_req(int, u_int32_t, void *);
302 void input_userauth_pk_ok(int, u_int32_t, void *);
303 void input_userauth_passwd_changereq(int, u_int32_t, void *);
304
305 int userauth_none(Authctxt *);
306 int userauth_pubkey(Authctxt *);
307 int userauth_passwd(Authctxt *);
308 int userauth_kbdint(Authctxt *);
309 int userauth_hostbased(Authctxt *);
310
311 #ifdef GSSAPI
312 int userauth_gssapi(Authctxt *authctxt);
313 void input_gssapi_response(int type, u_int32_t, void *);
314 void input_gssapi_token(int type, u_int32_t, void *);
315 void input_gssapi_hash(int type, u_int32_t, void *);
316 void input_gssapi_error(int, u_int32_t, void *);
317 void input_gssapi_errtok(int, u_int32_t, void *);
318 #endif
319
320 void userauth(Authctxt *, char *);
321
322 static int sign_and_send_pubkey(Authctxt *, Identity *);
323 static void pubkey_prepare(Authctxt *);
324 static void pubkey_cleanup(Authctxt *);
325 static Key *load_identity_file(char *, int);
326
327 static Authmethod *authmethod_get(char *authlist);
328 static Authmethod *authmethod_lookup(const char *name);
329 static char *authmethods_get(void);
330
331 Authmethod authmethods[] = {
332 #ifdef GSSAPI
333 {"gssapi-with-mic",
334 userauth_gssapi,
335 NULL,
336 &options.gss_authentication,
337 NULL},
338 #endif
339 {"hostbased",
340 userauth_hostbased,
341 NULL,
342 &options.hostbased_authentication,
343 NULL},
344 {"publickey",
345 userauth_pubkey,
346 NULL,
347 &options.pubkey_authentication,
348 NULL},
349 {"keyboard-interactive",
350 userauth_kbdint,
351 NULL,
352 &options.kbd_interactive_authentication,
353 &options.batch_mode},
354 {"password",
355 userauth_passwd,
356 NULL,
357 &options.password_authentication,
358 &options.batch_mode},
359 {"none",
360 userauth_none,
361 NULL,
362 NULL,
363 NULL},
364 {NULL, NULL, NULL, NULL, NULL}
365 };
366
367 void
ssh_userauth2(const char * local_user,const char * server_user,char * host,Sensitive * sensitive)368 ssh_userauth2(const char *local_user, const char *server_user, char *host,
369 Sensitive *sensitive)
370 {
371 Authctxt authctxt;
372 int type;
373
374 if (options.challenge_response_authentication)
375 options.kbd_interactive_authentication = 1;
376
377 packet_start(SSH2_MSG_SERVICE_REQUEST);
378 packet_put_cstring("ssh-userauth");
379 packet_send();
380 debug("SSH2_MSG_SERVICE_REQUEST sent");
381 packet_write_wait();
382 type = packet_read();
383 if (type != SSH2_MSG_SERVICE_ACCEPT)
384 fatal("Server denied authentication request: %d", type);
385 if (packet_remaining() > 0) {
386 char *reply = packet_get_string(NULL);
387 debug2("service_accept: %s", reply);
388 free(reply);
389 } else {
390 debug2("buggy server: service_accept w/o service");
391 }
392 packet_check_eom();
393 debug("SSH2_MSG_SERVICE_ACCEPT received");
394
395 if (options.preferred_authentications == NULL)
396 options.preferred_authentications = authmethods_get();
397
398 /* setup authentication context */
399 memset(&authctxt, 0, sizeof(authctxt));
400 pubkey_prepare(&authctxt);
401 authctxt.server_user = server_user;
402 authctxt.local_user = local_user;
403 authctxt.host = host;
404 authctxt.service = "ssh-connection"; /* service name */
405 authctxt.success = 0;
406 authctxt.method = authmethod_lookup("none");
407 authctxt.authlist = NULL;
408 authctxt.methoddata = NULL;
409 authctxt.sensitive = sensitive;
410 authctxt.info_req_seen = 0;
411 if (authctxt.method == NULL)
412 fatal("ssh_userauth2: internal error: cannot send userauth none request");
413
414 /* initial userauth request */
415 userauth_none(&authctxt);
416
417 dispatch_init(&input_userauth_error);
418 dispatch_set(SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
419 dispatch_set(SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
420 dispatch_set(SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
421 dispatch_run(DISPATCH_BLOCK, &authctxt.success, &authctxt); /* loop until success */
422
423 pubkey_cleanup(&authctxt);
424 dispatch_range(SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
425
426 #ifdef NONE_CIPHER_ENABLED
427 /*
428 * If the user explicitly requests to use the none cipher enable it
429 * post authentication and only if the right conditions are met: both
430 * of the NONE switches must be true and there must be no tty allocated.
431 */
432 if (options.none_switch == 1 && options.none_enabled == 1) {
433 if (!tty_flag) {
434 debug("Requesting none cipher re-keying...");
435 myproposal[PROPOSAL_ENC_ALGS_STOC] = "none";
436 myproposal[PROPOSAL_ENC_ALGS_CTOS] = "none";
437 kex_prop2buf(&xxx_kex->my, myproposal);
438 packet_request_rekeying();
439 fprintf(stderr, "WARNING: enabled NONE cipher\n");
440 } else {
441 /* Requested NONE cipher on an interactive session. */
442 debug("Cannot switch to NONE cipher with tty "
443 "allocated");
444 fprintf(stderr, "NONE cipher switch disabled given "
445 "a TTY is allocated\n");
446 }
447 }
448 #endif
449 debug("Authentication succeeded (%s).", authctxt.method->name);
450 }
451
452 void
userauth(Authctxt * authctxt,char * authlist)453 userauth(Authctxt *authctxt, char *authlist)
454 {
455 if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
456 authctxt->method->cleanup(authctxt);
457
458 free(authctxt->methoddata);
459 authctxt->methoddata = NULL;
460 if (authlist == NULL) {
461 authlist = authctxt->authlist;
462 } else {
463 free(authctxt->authlist);
464 authctxt->authlist = authlist;
465 }
466 for (;;) {
467 Authmethod *method = authmethod_get(authlist);
468 if (method == NULL)
469 fatal("Permission denied (%s).", authlist);
470 authctxt->method = method;
471
472 /* reset the per method handler */
473 dispatch_range(SSH2_MSG_USERAUTH_PER_METHOD_MIN,
474 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
475
476 /* and try new method */
477 if (method->userauth(authctxt) != 0) {
478 debug2("we sent a %s packet, wait for reply", method->name);
479 break;
480 } else {
481 debug2("we did not send a packet, disable method");
482 method->enabled = NULL;
483 }
484 }
485 }
486
487 /* ARGSUSED */
488 void
input_userauth_error(int type,u_int32_t seq,void * ctxt)489 input_userauth_error(int type, u_int32_t seq, void *ctxt)
490 {
491 fatal("input_userauth_error: bad message during authentication: "
492 "type %d", type);
493 }
494
495 /* ARGSUSED */
496 void
input_userauth_banner(int type,u_int32_t seq,void * ctxt)497 input_userauth_banner(int type, u_int32_t seq, void *ctxt)
498 {
499 char *msg, *raw, *lang;
500 u_int len;
501
502 debug3("input_userauth_banner");
503 raw = packet_get_string(&len);
504 lang = packet_get_string(NULL);
505 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO) {
506 if (len > 65536)
507 len = 65536;
508 msg = xmalloc(len * 4 + 1); /* max expansion from strnvis() */
509 strnvis(msg, raw, len * 4 + 1, VIS_SAFE|VIS_OCTAL|VIS_NOSLASH);
510 fprintf(stderr, "%s", msg);
511 free(msg);
512 }
513 free(raw);
514 free(lang);
515 }
516
517 /* ARGSUSED */
518 void
input_userauth_success(int type,u_int32_t seq,void * ctxt)519 input_userauth_success(int type, u_int32_t seq, void *ctxt)
520 {
521 Authctxt *authctxt = ctxt;
522
523 if (authctxt == NULL)
524 fatal("input_userauth_success: no authentication context");
525 free(authctxt->authlist);
526 authctxt->authlist = NULL;
527 if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
528 authctxt->method->cleanup(authctxt);
529 free(authctxt->methoddata);
530 authctxt->methoddata = NULL;
531 authctxt->success = 1; /* break out */
532 }
533
534 void
input_userauth_success_unexpected(int type,u_int32_t seq,void * ctxt)535 input_userauth_success_unexpected(int type, u_int32_t seq, void *ctxt)
536 {
537 Authctxt *authctxt = ctxt;
538
539 if (authctxt == NULL)
540 fatal("%s: no authentication context", __func__);
541
542 fatal("Unexpected authentication success during %s.",
543 authctxt->method->name);
544 }
545
546 /* ARGSUSED */
547 void
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 logit("Authenticated with partial success.");
563 /* reset state */
564 pubkey_cleanup(authctxt);
565 pubkey_prepare(authctxt);
566 }
567 debug("Authentications that can continue: %s", authlist);
568
569 userauth(authctxt, authlist);
570 }
571
572 /* ARGSUSED */
573 void
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 fp = key_fingerprint(key, SSH_FP_MD5, SSH_FP_HEX);
618 debug2("input_userauth_pk_ok: fp %s", fp);
619 free(fp);
620
621 /*
622 * search keys in the reverse order, because last candidate has been
623 * moved to the end of the queue. this also avoids confusion by
624 * duplicate keys
625 */
626 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
627 if (key_equal(key, id->key)) {
628 sent = sign_and_send_pubkey(authctxt, id);
629 break;
630 }
631 }
632 done:
633 if (key != NULL)
634 key_free(key);
635 free(pkalg);
636 free(pkblob);
637
638 /* try another method if we did not send a packet */
639 if (sent == 0)
640 userauth(authctxt, NULL);
641 }
642
643 #ifdef GSSAPI
644 int
userauth_gssapi(Authctxt * authctxt)645 userauth_gssapi(Authctxt *authctxt)
646 {
647 Gssctxt *gssctxt = NULL;
648 static gss_OID_set gss_supported = NULL;
649 static u_int mech = 0;
650 OM_uint32 min;
651 int ok = 0;
652
653 /* Try one GSSAPI method at a time, rather than sending them all at
654 * once. */
655
656 if (gss_supported == NULL)
657 gss_indicate_mechs(&min, &gss_supported);
658
659 /* Check to see if the mechanism is usable before we offer it */
660 while (mech < gss_supported->count && !ok) {
661 /* My DER encoding requires length<128 */
662 if (gss_supported->elements[mech].length < 128 &&
663 ssh_gssapi_check_mechanism(&gssctxt,
664 &gss_supported->elements[mech], authctxt->host)) {
665 ok = 1; /* Mechanism works */
666 } else {
667 mech++;
668 }
669 }
670
671 if (!ok)
672 return 0;
673
674 authctxt->methoddata=(void *)gssctxt;
675
676 packet_start(SSH2_MSG_USERAUTH_REQUEST);
677 packet_put_cstring(authctxt->server_user);
678 packet_put_cstring(authctxt->service);
679 packet_put_cstring(authctxt->method->name);
680
681 packet_put_int(1);
682
683 packet_put_int((gss_supported->elements[mech].length) + 2);
684 packet_put_char(SSH_GSS_OIDTYPE);
685 packet_put_char(gss_supported->elements[mech].length);
686 packet_put_raw(gss_supported->elements[mech].elements,
687 gss_supported->elements[mech].length);
688
689 packet_send();
690
691 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
692 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
693 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
694 dispatch_set(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
695
696 mech++; /* Move along to next candidate */
697
698 return 1;
699 }
700
701 static OM_uint32
process_gssapi_token(void * ctxt,gss_buffer_t recv_tok)702 process_gssapi_token(void *ctxt, gss_buffer_t recv_tok)
703 {
704 Authctxt *authctxt = ctxt;
705 Gssctxt *gssctxt = authctxt->methoddata;
706 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
707 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
708 gss_buffer_desc gssbuf;
709 OM_uint32 status, ms, flags;
710 Buffer b;
711
712 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
713 recv_tok, &send_tok, &flags);
714
715 if (send_tok.length > 0) {
716 if (GSS_ERROR(status))
717 packet_start(SSH2_MSG_USERAUTH_GSSAPI_ERRTOK);
718 else
719 packet_start(SSH2_MSG_USERAUTH_GSSAPI_TOKEN);
720
721 packet_put_string(send_tok.value, send_tok.length);
722 packet_send();
723 gss_release_buffer(&ms, &send_tok);
724 }
725
726 if (status == GSS_S_COMPLETE) {
727 /* send either complete or MIC, depending on mechanism */
728 if (!(flags & GSS_C_INTEG_FLAG)) {
729 packet_start(SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE);
730 packet_send();
731 } else {
732 ssh_gssapi_buildmic(&b, authctxt->server_user,
733 authctxt->service, "gssapi-with-mic");
734
735 gssbuf.value = buffer_ptr(&b);
736 gssbuf.length = buffer_len(&b);
737
738 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
739
740 if (!GSS_ERROR(status)) {
741 packet_start(SSH2_MSG_USERAUTH_GSSAPI_MIC);
742 packet_put_string(mic.value, mic.length);
743
744 packet_send();
745 }
746
747 buffer_free(&b);
748 gss_release_buffer(&ms, &mic);
749 }
750 }
751
752 return status;
753 }
754
755 /* ARGSUSED */
756 void
input_gssapi_response(int type,u_int32_t plen,void * ctxt)757 input_gssapi_response(int type, u_int32_t plen, void *ctxt)
758 {
759 Authctxt *authctxt = ctxt;
760 Gssctxt *gssctxt;
761 int oidlen;
762 char *oidv;
763
764 if (authctxt == NULL)
765 fatal("input_gssapi_response: no authentication context");
766 gssctxt = authctxt->methoddata;
767
768 /* Setup our OID */
769 oidv = packet_get_string(&oidlen);
770
771 if (oidlen <= 2 ||
772 oidv[0] != SSH_GSS_OIDTYPE ||
773 oidv[1] != oidlen - 2) {
774 free(oidv);
775 debug("Badly encoded mechanism OID received");
776 userauth(authctxt, NULL);
777 return;
778 }
779
780 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
781 fatal("Server returned different OID than expected");
782
783 packet_check_eom();
784
785 free(oidv);
786
787 if (GSS_ERROR(process_gssapi_token(ctxt, GSS_C_NO_BUFFER))) {
788 /* Start again with next method on list */
789 debug("Trying to start again");
790 userauth(authctxt, NULL);
791 return;
792 }
793 }
794
795 /* ARGSUSED */
796 void
input_gssapi_token(int type,u_int32_t plen,void * ctxt)797 input_gssapi_token(int type, u_int32_t plen, void *ctxt)
798 {
799 Authctxt *authctxt = ctxt;
800 gss_buffer_desc recv_tok;
801 OM_uint32 status;
802 u_int slen;
803
804 if (authctxt == NULL)
805 fatal("input_gssapi_response: no authentication context");
806
807 recv_tok.value = packet_get_string(&slen);
808 recv_tok.length = slen; /* safe typecast */
809
810 packet_check_eom();
811
812 status = process_gssapi_token(ctxt, &recv_tok);
813
814 free(recv_tok.value);
815
816 if (GSS_ERROR(status)) {
817 /* Start again with the next method in the list */
818 userauth(authctxt, NULL);
819 return;
820 }
821 }
822
823 /* ARGSUSED */
824 void
input_gssapi_errtok(int type,u_int32_t plen,void * ctxt)825 input_gssapi_errtok(int type, u_int32_t plen, void *ctxt)
826 {
827 Authctxt *authctxt = ctxt;
828 Gssctxt *gssctxt;
829 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
830 gss_buffer_desc recv_tok;
831 OM_uint32 ms;
832 u_int len;
833
834 if (authctxt == NULL)
835 fatal("input_gssapi_response: no authentication context");
836 gssctxt = authctxt->methoddata;
837
838 recv_tok.value = packet_get_string(&len);
839 recv_tok.length = len;
840
841 packet_check_eom();
842
843 /* Stick it into GSSAPI and see what it says */
844 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
845 &recv_tok, &send_tok, NULL);
846
847 free(recv_tok.value);
848 gss_release_buffer(&ms, &send_tok);
849
850 /* Server will be returning a failed packet after this one */
851 }
852
853 /* ARGSUSED */
854 void
input_gssapi_error(int type,u_int32_t plen,void * ctxt)855 input_gssapi_error(int type, u_int32_t plen, void *ctxt)
856 {
857 char *msg;
858 char *lang;
859
860 /* maj */(void)packet_get_int();
861 /* min */(void)packet_get_int();
862 msg=packet_get_string(NULL);
863 lang=packet_get_string(NULL);
864
865 packet_check_eom();
866
867 debug("Server GSSAPI Error:\n%s", msg);
868 free(msg);
869 free(lang);
870 }
871 #endif /* GSSAPI */
872
873 int
userauth_none(Authctxt * authctxt)874 userauth_none(Authctxt *authctxt)
875 {
876 /* initial userauth request */
877 packet_start(SSH2_MSG_USERAUTH_REQUEST);
878 packet_put_cstring(authctxt->server_user);
879 packet_put_cstring(authctxt->service);
880 packet_put_cstring(authctxt->method->name);
881 packet_send();
882 return 1;
883 }
884
885 int
userauth_passwd(Authctxt * authctxt)886 userauth_passwd(Authctxt *authctxt)
887 {
888 static int attempt = 0;
889 char prompt[150];
890 char *password;
891 const char *host = options.host_key_alias ? options.host_key_alias :
892 authctxt->host;
893
894 if (attempt++ >= options.number_of_password_prompts)
895 return 0;
896
897 if (attempt != 1)
898 error("Permission denied, please try again.");
899
900 snprintf(prompt, sizeof(prompt), "%.30s@%.128s's password: ",
901 authctxt->server_user, host);
902 password = read_passphrase(prompt, 0);
903 packet_start(SSH2_MSG_USERAUTH_REQUEST);
904 packet_put_cstring(authctxt->server_user);
905 packet_put_cstring(authctxt->service);
906 packet_put_cstring(authctxt->method->name);
907 packet_put_char(0);
908 packet_put_cstring(password);
909 explicit_bzero(password, strlen(password));
910 free(password);
911 packet_add_padding(64);
912 packet_send();
913
914 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
915 &input_userauth_passwd_changereq);
916
917 return 1;
918 }
919
920 /*
921 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
922 */
923 /* ARGSUSED */
924 void
input_userauth_passwd_changereq(int type,u_int32_t seqnr,void * ctxt)925 input_userauth_passwd_changereq(int type, u_int32_t seqnr, void *ctxt)
926 {
927 Authctxt *authctxt = ctxt;
928 char *info, *lang, *password = NULL, *retype = NULL;
929 char prompt[150];
930 const char *host = options.host_key_alias ? options.host_key_alias :
931 authctxt->host;
932
933 debug2("input_userauth_passwd_changereq");
934
935 if (authctxt == NULL)
936 fatal("input_userauth_passwd_changereq: "
937 "no authentication context");
938
939 info = packet_get_string(NULL);
940 lang = packet_get_string(NULL);
941 if (strlen(info) > 0)
942 logit("%s", info);
943 free(info);
944 free(lang);
945 packet_start(SSH2_MSG_USERAUTH_REQUEST);
946 packet_put_cstring(authctxt->server_user);
947 packet_put_cstring(authctxt->service);
948 packet_put_cstring(authctxt->method->name);
949 packet_put_char(1); /* additional info */
950 snprintf(prompt, sizeof(prompt),
951 "Enter %.30s@%.128s's old password: ",
952 authctxt->server_user, host);
953 password = read_passphrase(prompt, 0);
954 packet_put_cstring(password);
955 explicit_bzero(password, strlen(password));
956 free(password);
957 password = NULL;
958 while (password == NULL) {
959 snprintf(prompt, sizeof(prompt),
960 "Enter %.30s@%.128s's new password: ",
961 authctxt->server_user, host);
962 password = read_passphrase(prompt, RP_ALLOW_EOF);
963 if (password == NULL) {
964 /* bail out */
965 return;
966 }
967 snprintf(prompt, sizeof(prompt),
968 "Retype %.30s@%.128s's new password: ",
969 authctxt->server_user, host);
970 retype = read_passphrase(prompt, 0);
971 if (strcmp(password, retype) != 0) {
972 explicit_bzero(password, strlen(password));
973 free(password);
974 logit("Mismatch; try again, EOF to quit.");
975 password = NULL;
976 }
977 explicit_bzero(retype, strlen(retype));
978 free(retype);
979 }
980 packet_put_cstring(password);
981 explicit_bzero(password, strlen(password));
982 free(password);
983 packet_add_padding(64);
984 packet_send();
985
986 dispatch_set(SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
987 &input_userauth_passwd_changereq);
988 }
989
990 static int
identity_sign(Identity * id,u_char ** sigp,u_int * lenp,u_char * data,u_int datalen)991 identity_sign(Identity *id, u_char **sigp, u_int *lenp,
992 u_char *data, u_int datalen)
993 {
994 Key *prv;
995 int ret;
996
997 /* the agent supports this key */
998 if (id->ac)
999 return (ssh_agent_sign(id->ac, id->key, sigp, lenp,
1000 data, datalen));
1001 /*
1002 * we have already loaded the private key or
1003 * the private key is stored in external hardware
1004 */
1005 if (id->isprivate || (id->key->flags & KEY_FLAG_EXT))
1006 return (key_sign(id->key, sigp, lenp, data, datalen));
1007 /* load the private key from the file */
1008 if ((prv = load_identity_file(id->filename, id->userprovided)) == NULL)
1009 return (-1);
1010 ret = key_sign(prv, sigp, lenp, data, datalen);
1011 key_free(prv);
1012 return (ret);
1013 }
1014
1015 static int
sign_and_send_pubkey(Authctxt * authctxt,Identity * id)1016 sign_and_send_pubkey(Authctxt *authctxt, Identity *id)
1017 {
1018 Buffer b;
1019 u_char *blob, *signature;
1020 u_int bloblen, slen;
1021 u_int skip = 0;
1022 int ret = -1;
1023 int have_sig = 1;
1024 char *fp;
1025
1026 fp = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
1027 debug3("sign_and_send_pubkey: %s %s", key_type(id->key), fp);
1028 free(fp);
1029
1030 if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1031 /* we cannot handle this key */
1032 debug3("sign_and_send_pubkey: cannot handle key");
1033 return 0;
1034 }
1035 /* data to be signed */
1036 buffer_init(&b);
1037 if (datafellows & SSH_OLD_SESSIONID) {
1038 buffer_append(&b, session_id2, session_id2_len);
1039 skip = session_id2_len;
1040 } else {
1041 buffer_put_string(&b, session_id2, session_id2_len);
1042 skip = buffer_len(&b);
1043 }
1044 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1045 buffer_put_cstring(&b, authctxt->server_user);
1046 buffer_put_cstring(&b,
1047 datafellows & SSH_BUG_PKSERVICE ?
1048 "ssh-userauth" :
1049 authctxt->service);
1050 if (datafellows & SSH_BUG_PKAUTH) {
1051 buffer_put_char(&b, have_sig);
1052 } else {
1053 buffer_put_cstring(&b, authctxt->method->name);
1054 buffer_put_char(&b, have_sig);
1055 buffer_put_cstring(&b, key_ssh_name(id->key));
1056 }
1057 buffer_put_string(&b, blob, bloblen);
1058
1059 /* generate signature */
1060 ret = identity_sign(id, &signature, &slen,
1061 buffer_ptr(&b), buffer_len(&b));
1062 if (ret == -1) {
1063 free(blob);
1064 buffer_free(&b);
1065 return 0;
1066 }
1067 #ifdef DEBUG_PK
1068 buffer_dump(&b);
1069 #endif
1070 if (datafellows & SSH_BUG_PKSERVICE) {
1071 buffer_clear(&b);
1072 buffer_append(&b, session_id2, session_id2_len);
1073 skip = session_id2_len;
1074 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1075 buffer_put_cstring(&b, authctxt->server_user);
1076 buffer_put_cstring(&b, authctxt->service);
1077 buffer_put_cstring(&b, authctxt->method->name);
1078 buffer_put_char(&b, have_sig);
1079 if (!(datafellows & SSH_BUG_PKAUTH))
1080 buffer_put_cstring(&b, key_ssh_name(id->key));
1081 buffer_put_string(&b, blob, bloblen);
1082 }
1083 free(blob);
1084
1085 /* append signature */
1086 buffer_put_string(&b, signature, slen);
1087 free(signature);
1088
1089 /* skip session id and packet type */
1090 if (buffer_len(&b) < skip + 1)
1091 fatal("userauth_pubkey: internal error");
1092 buffer_consume(&b, skip + 1);
1093
1094 /* put remaining data from buffer into packet */
1095 packet_start(SSH2_MSG_USERAUTH_REQUEST);
1096 packet_put_raw(buffer_ptr(&b), buffer_len(&b));
1097 buffer_free(&b);
1098 packet_send();
1099
1100 return 1;
1101 }
1102
1103 static int
send_pubkey_test(Authctxt * authctxt,Identity * id)1104 send_pubkey_test(Authctxt *authctxt, Identity *id)
1105 {
1106 u_char *blob;
1107 u_int bloblen, have_sig = 0;
1108
1109 debug3("send_pubkey_test");
1110
1111 if (key_to_blob(id->key, &blob, &bloblen) == 0) {
1112 /* we cannot handle this key */
1113 debug3("send_pubkey_test: cannot handle key");
1114 return 0;
1115 }
1116 /* register callback for USERAUTH_PK_OK message */
1117 dispatch_set(SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1118
1119 packet_start(SSH2_MSG_USERAUTH_REQUEST);
1120 packet_put_cstring(authctxt->server_user);
1121 packet_put_cstring(authctxt->service);
1122 packet_put_cstring(authctxt->method->name);
1123 packet_put_char(have_sig);
1124 if (!(datafellows & SSH_BUG_PKAUTH))
1125 packet_put_cstring(key_ssh_name(id->key));
1126 packet_put_string(blob, bloblen);
1127 free(blob);
1128 packet_send();
1129 return 1;
1130 }
1131
1132 static Key *
load_identity_file(char * filename,int userprovided)1133 load_identity_file(char *filename, int userprovided)
1134 {
1135 Key *private;
1136 char prompt[300], *passphrase;
1137 int perm_ok = 0, quit, i;
1138 struct stat st;
1139
1140 if (stat(filename, &st) < 0) {
1141 (userprovided ? logit : debug3)("no such identity: %s: %s",
1142 filename, strerror(errno));
1143 return NULL;
1144 }
1145 private = key_load_private_type(KEY_UNSPEC, filename, "", NULL, &perm_ok);
1146 if (!perm_ok) {
1147 if (private != NULL)
1148 key_free(private);
1149 return NULL;
1150 }
1151 if (private == NULL) {
1152 if (options.batch_mode)
1153 return NULL;
1154 snprintf(prompt, sizeof prompt,
1155 "Enter passphrase for key '%.100s': ", filename);
1156 for (i = 0; i < options.number_of_password_prompts; i++) {
1157 passphrase = read_passphrase(prompt, 0);
1158 if (strcmp(passphrase, "") != 0) {
1159 private = key_load_private_type(KEY_UNSPEC,
1160 filename, passphrase, NULL, NULL);
1161 quit = 0;
1162 } else {
1163 debug2("no passphrase given, try next key");
1164 quit = 1;
1165 }
1166 explicit_bzero(passphrase, strlen(passphrase));
1167 free(passphrase);
1168 if (private != NULL || quit)
1169 break;
1170 debug2("bad passphrase given, try again...");
1171 }
1172 }
1173 return private;
1174 }
1175
1176 /*
1177 * try keys in the following order:
1178 * 1. agent keys that are found in the config file
1179 * 2. other agent keys
1180 * 3. keys that are only listed in the config file
1181 */
1182 static void
pubkey_prepare(Authctxt * authctxt)1183 pubkey_prepare(Authctxt *authctxt)
1184 {
1185 Identity *id, *id2, *tmp;
1186 Idlist agent, files, *preferred;
1187 Key *key;
1188 AuthenticationConnection *ac;
1189 char *comment;
1190 int i, found;
1191
1192 TAILQ_INIT(&agent); /* keys from the agent */
1193 TAILQ_INIT(&files); /* keys from the config file */
1194 preferred = &authctxt->keys;
1195 TAILQ_INIT(preferred); /* preferred order of keys */
1196
1197 /* list of keys stored in the filesystem and PKCS#11 */
1198 for (i = 0; i < options.num_identity_files; i++) {
1199 key = options.identity_keys[i];
1200 if (key && key->type == KEY_RSA1)
1201 continue;
1202 if (key && key->cert && key->cert->type != SSH2_CERT_TYPE_USER)
1203 continue;
1204 options.identity_keys[i] = NULL;
1205 id = xcalloc(1, sizeof(*id));
1206 id->key = key;
1207 id->filename = xstrdup(options.identity_files[i]);
1208 id->userprovided = options.identity_file_userprovided[i];
1209 TAILQ_INSERT_TAIL(&files, id, next);
1210 }
1211 /* Prefer PKCS11 keys that are explicitly listed */
1212 TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1213 if (id->key == NULL || (id->key->flags & KEY_FLAG_EXT) == 0)
1214 continue;
1215 found = 0;
1216 TAILQ_FOREACH(id2, &files, next) {
1217 if (id2->key == NULL ||
1218 (id2->key->flags & KEY_FLAG_EXT) != 0)
1219 continue;
1220 if (key_equal(id->key, id2->key)) {
1221 TAILQ_REMOVE(&files, id, next);
1222 TAILQ_INSERT_TAIL(preferred, id, next);
1223 found = 1;
1224 break;
1225 }
1226 }
1227 /* If IdentitiesOnly set and key not found then don't use it */
1228 if (!found && options.identities_only) {
1229 TAILQ_REMOVE(&files, id, next);
1230 explicit_bzero(id, sizeof(*id));
1231 free(id);
1232 }
1233 }
1234 /* list of keys supported by the agent */
1235 if ((ac = ssh_get_authentication_connection())) {
1236 for (key = ssh_get_first_identity(ac, &comment, 2);
1237 key != NULL;
1238 key = ssh_get_next_identity(ac, &comment, 2)) {
1239 found = 0;
1240 TAILQ_FOREACH(id, &files, next) {
1241 /* agent keys from the config file are preferred */
1242 if (key_equal(key, id->key)) {
1243 key_free(key);
1244 free(comment);
1245 TAILQ_REMOVE(&files, id, next);
1246 TAILQ_INSERT_TAIL(preferred, id, next);
1247 id->ac = ac;
1248 found = 1;
1249 break;
1250 }
1251 }
1252 if (!found && !options.identities_only) {
1253 id = xcalloc(1, sizeof(*id));
1254 id->key = key;
1255 id->filename = comment;
1256 id->ac = ac;
1257 TAILQ_INSERT_TAIL(&agent, id, next);
1258 }
1259 }
1260 /* append remaining agent keys */
1261 for (id = TAILQ_FIRST(&agent); id; id = TAILQ_FIRST(&agent)) {
1262 TAILQ_REMOVE(&agent, id, next);
1263 TAILQ_INSERT_TAIL(preferred, id, next);
1264 }
1265 authctxt->agent = ac;
1266 }
1267 /* append remaining keys from the config file */
1268 for (id = TAILQ_FIRST(&files); id; id = TAILQ_FIRST(&files)) {
1269 TAILQ_REMOVE(&files, id, next);
1270 TAILQ_INSERT_TAIL(preferred, id, next);
1271 }
1272 TAILQ_FOREACH(id, preferred, next) {
1273 debug2("key: %s (%p),%s", id->filename, id->key,
1274 id->userprovided ? " explicit" : "");
1275 }
1276 }
1277
1278 static void
pubkey_cleanup(Authctxt * authctxt)1279 pubkey_cleanup(Authctxt *authctxt)
1280 {
1281 Identity *id;
1282
1283 if (authctxt->agent != NULL)
1284 ssh_close_authentication_connection(authctxt->agent);
1285 for (id = TAILQ_FIRST(&authctxt->keys); id;
1286 id = TAILQ_FIRST(&authctxt->keys)) {
1287 TAILQ_REMOVE(&authctxt->keys, id, next);
1288 if (id->key)
1289 key_free(id->key);
1290 free(id->filename);
1291 free(id);
1292 }
1293 }
1294
1295 int
userauth_pubkey(Authctxt * authctxt)1296 userauth_pubkey(Authctxt *authctxt)
1297 {
1298 Identity *id;
1299 int sent = 0;
1300
1301 while ((id = TAILQ_FIRST(&authctxt->keys))) {
1302 if (id->tried++)
1303 return (0);
1304 /* move key to the end of the queue */
1305 TAILQ_REMOVE(&authctxt->keys, id, next);
1306 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1307 /*
1308 * send a test message if we have the public key. for
1309 * encrypted keys we cannot do this and have to load the
1310 * private key instead
1311 */
1312 if (id->key != NULL) {
1313 if (key_type_plain(id->key->type) == KEY_RSA &&
1314 (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1315 debug("Skipped %s key %s for RSA/MD5 server",
1316 key_type(id->key), id->filename);
1317 } else if (id->key->type != KEY_RSA1) {
1318 debug("Offering %s public key: %s",
1319 key_type(id->key), id->filename);
1320 sent = send_pubkey_test(authctxt, id);
1321 }
1322 } else {
1323 debug("Trying private key: %s", id->filename);
1324 id->key = load_identity_file(id->filename,
1325 id->userprovided);
1326 if (id->key != NULL) {
1327 id->isprivate = 1;
1328 if (key_type_plain(id->key->type) == KEY_RSA &&
1329 (datafellows & SSH_BUG_RSASIGMD5) != 0) {
1330 debug("Skipped %s key %s for RSA/MD5 "
1331 "server", key_type(id->key),
1332 id->filename);
1333 } else {
1334 sent = sign_and_send_pubkey(
1335 authctxt, id);
1336 }
1337 key_free(id->key);
1338 id->key = NULL;
1339 }
1340 }
1341 if (sent)
1342 return (sent);
1343 }
1344 return (0);
1345 }
1346
1347 /*
1348 * Send userauth request message specifying keyboard-interactive method.
1349 */
1350 int
userauth_kbdint(Authctxt * authctxt)1351 userauth_kbdint(Authctxt *authctxt)
1352 {
1353 static int attempt = 0;
1354
1355 if (attempt++ >= options.number_of_password_prompts)
1356 return 0;
1357 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1358 if (attempt > 1 && !authctxt->info_req_seen) {
1359 debug3("userauth_kbdint: disable: no info_req_seen");
1360 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1361 return 0;
1362 }
1363
1364 debug2("userauth_kbdint");
1365 packet_start(SSH2_MSG_USERAUTH_REQUEST);
1366 packet_put_cstring(authctxt->server_user);
1367 packet_put_cstring(authctxt->service);
1368 packet_put_cstring(authctxt->method->name);
1369 packet_put_cstring(""); /* lang */
1370 packet_put_cstring(options.kbd_interactive_devices ?
1371 options.kbd_interactive_devices : "");
1372 packet_send();
1373
1374 dispatch_set(SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1375 return 1;
1376 }
1377
1378 /*
1379 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1380 */
1381 void
input_userauth_info_req(int type,u_int32_t seq,void * ctxt)1382 input_userauth_info_req(int type, u_int32_t seq, void *ctxt)
1383 {
1384 Authctxt *authctxt = ctxt;
1385 char *name, *inst, *lang, *prompt, *response;
1386 u_int num_prompts, i;
1387 int echo = 0;
1388
1389 debug2("input_userauth_info_req");
1390
1391 if (authctxt == NULL)
1392 fatal("input_userauth_info_req: no authentication context");
1393
1394 authctxt->info_req_seen = 1;
1395
1396 name = packet_get_string(NULL);
1397 inst = packet_get_string(NULL);
1398 lang = packet_get_string(NULL);
1399 if (strlen(name) > 0)
1400 logit("%s", name);
1401 if (strlen(inst) > 0)
1402 logit("%s", inst);
1403 free(name);
1404 free(inst);
1405 free(lang);
1406
1407 num_prompts = packet_get_int();
1408 /*
1409 * Begin to build info response packet based on prompts requested.
1410 * We commit to providing the correct number of responses, so if
1411 * further on we run into a problem that prevents this, we have to
1412 * be sure and clean this up and send a correct error response.
1413 */
1414 packet_start(SSH2_MSG_USERAUTH_INFO_RESPONSE);
1415 packet_put_int(num_prompts);
1416
1417 debug2("input_userauth_info_req: num_prompts %d", num_prompts);
1418 for (i = 0; i < num_prompts; i++) {
1419 prompt = packet_get_string(NULL);
1420 echo = packet_get_char();
1421
1422 response = read_passphrase(prompt, echo ? RP_ECHO : 0);
1423
1424 packet_put_cstring(response);
1425 explicit_bzero(response, strlen(response));
1426 free(response);
1427 free(prompt);
1428 }
1429 packet_check_eom(); /* done with parsing incoming message. */
1430
1431 packet_add_padding(64);
1432 packet_send();
1433 }
1434
1435 static int
ssh_keysign(Key * key,u_char ** sigp,u_int * lenp,u_char * data,u_int datalen)1436 ssh_keysign(Key *key, u_char **sigp, u_int *lenp,
1437 u_char *data, u_int datalen)
1438 {
1439 Buffer b;
1440 struct stat st;
1441 pid_t pid;
1442 int to[2], from[2], status, version = 2;
1443
1444 debug2("ssh_keysign called");
1445
1446 if (stat(_PATH_SSH_KEY_SIGN, &st) < 0) {
1447 error("ssh_keysign: not installed: %s", strerror(errno));
1448 return -1;
1449 }
1450 if (fflush(stdout) != 0)
1451 error("ssh_keysign: fflush: %s", strerror(errno));
1452 if (pipe(to) < 0) {
1453 error("ssh_keysign: pipe: %s", strerror(errno));
1454 return -1;
1455 }
1456 if (pipe(from) < 0) {
1457 error("ssh_keysign: pipe: %s", strerror(errno));
1458 return -1;
1459 }
1460 if ((pid = fork()) < 0) {
1461 error("ssh_keysign: fork: %s", strerror(errno));
1462 return -1;
1463 }
1464 if (pid == 0) {
1465 /* keep the socket on exec */
1466 fcntl(packet_get_connection_in(), F_SETFD, 0);
1467 permanently_drop_suid(getuid());
1468 close(from[0]);
1469 if (dup2(from[1], STDOUT_FILENO) < 0)
1470 fatal("ssh_keysign: dup2: %s", strerror(errno));
1471 close(to[1]);
1472 if (dup2(to[0], STDIN_FILENO) < 0)
1473 fatal("ssh_keysign: dup2: %s", strerror(errno));
1474 close(from[1]);
1475 close(to[0]);
1476 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *) 0);
1477 fatal("ssh_keysign: exec(%s): %s", _PATH_SSH_KEY_SIGN,
1478 strerror(errno));
1479 }
1480 close(from[1]);
1481 close(to[0]);
1482
1483 buffer_init(&b);
1484 buffer_put_int(&b, packet_get_connection_in()); /* send # of socket */
1485 buffer_put_string(&b, data, datalen);
1486 if (ssh_msg_send(to[1], version, &b) == -1)
1487 fatal("ssh_keysign: couldn't send request");
1488
1489 if (ssh_msg_recv(from[0], &b) < 0) {
1490 error("ssh_keysign: no reply");
1491 buffer_free(&b);
1492 return -1;
1493 }
1494 close(from[0]);
1495 close(to[1]);
1496
1497 while (waitpid(pid, &status, 0) < 0)
1498 if (errno != EINTR)
1499 break;
1500
1501 if (buffer_get_char(&b) != version) {
1502 error("ssh_keysign: bad version");
1503 buffer_free(&b);
1504 return -1;
1505 }
1506 *sigp = buffer_get_string(&b, lenp);
1507 buffer_free(&b);
1508
1509 return 0;
1510 }
1511
1512 int
userauth_hostbased(Authctxt * authctxt)1513 userauth_hostbased(Authctxt *authctxt)
1514 {
1515 Key *private = NULL;
1516 Sensitive *sensitive = authctxt->sensitive;
1517 Buffer b;
1518 u_char *signature, *blob;
1519 char *chost, *pkalg, *p;
1520 const char *service;
1521 u_int blen, slen;
1522 int ok, i, found = 0;
1523
1524 /* check for a useful key */
1525 for (i = 0; i < sensitive->nkeys; i++) {
1526 private = sensitive->keys[i];
1527 if (private && private->type != KEY_RSA1) {
1528 found = 1;
1529 /* we take and free the key */
1530 sensitive->keys[i] = NULL;
1531 break;
1532 }
1533 }
1534 if (!found) {
1535 debug("No more client hostkeys for hostbased authentication.");
1536 return 0;
1537 }
1538 if (key_to_blob(private, &blob, &blen) == 0) {
1539 key_free(private);
1540 return 0;
1541 }
1542 /* figure out a name for the client host */
1543 p = get_local_name(packet_get_connection_in());
1544 if (p == NULL) {
1545 error("userauth_hostbased: cannot get local ipaddr/name");
1546 key_free(private);
1547 free(blob);
1548 return 0;
1549 }
1550 xasprintf(&chost, "%s.", p);
1551 debug2("userauth_hostbased: chost %s", chost);
1552 free(p);
1553
1554 service = datafellows & SSH_BUG_HBSERVICE ? "ssh-userauth" :
1555 authctxt->service;
1556 pkalg = xstrdup(key_ssh_name(private));
1557 buffer_init(&b);
1558 /* construct data */
1559 buffer_put_string(&b, session_id2, session_id2_len);
1560 buffer_put_char(&b, SSH2_MSG_USERAUTH_REQUEST);
1561 buffer_put_cstring(&b, authctxt->server_user);
1562 buffer_put_cstring(&b, service);
1563 buffer_put_cstring(&b, authctxt->method->name);
1564 buffer_put_cstring(&b, pkalg);
1565 buffer_put_string(&b, blob, blen);
1566 buffer_put_cstring(&b, chost);
1567 buffer_put_cstring(&b, authctxt->local_user);
1568 #ifdef DEBUG_PK
1569 buffer_dump(&b);
1570 #endif
1571 if (sensitive->external_keysign)
1572 ok = ssh_keysign(private, &signature, &slen,
1573 buffer_ptr(&b), buffer_len(&b));
1574 else
1575 ok = key_sign(private, &signature, &slen,
1576 buffer_ptr(&b), buffer_len(&b));
1577 key_free(private);
1578 buffer_free(&b);
1579 if (ok != 0) {
1580 error("key_sign failed");
1581 free(chost);
1582 free(pkalg);
1583 free(blob);
1584 return 0;
1585 }
1586 packet_start(SSH2_MSG_USERAUTH_REQUEST);
1587 packet_put_cstring(authctxt->server_user);
1588 packet_put_cstring(authctxt->service);
1589 packet_put_cstring(authctxt->method->name);
1590 packet_put_cstring(pkalg);
1591 packet_put_string(blob, blen);
1592 packet_put_cstring(chost);
1593 packet_put_cstring(authctxt->local_user);
1594 packet_put_string(signature, slen);
1595 explicit_bzero(signature, slen);
1596 free(signature);
1597 free(chost);
1598 free(pkalg);
1599 free(blob);
1600
1601 packet_send();
1602 return 1;
1603 }
1604
1605 /* find auth method */
1606
1607 /*
1608 * given auth method name, if configurable options permit this method fill
1609 * in auth_ident field and return true, otherwise return false.
1610 */
1611 static int
authmethod_is_enabled(Authmethod * method)1612 authmethod_is_enabled(Authmethod *method)
1613 {
1614 if (method == NULL)
1615 return 0;
1616 /* return false if options indicate this method is disabled */
1617 if (method->enabled == NULL || *method->enabled == 0)
1618 return 0;
1619 /* return false if batch mode is enabled but method needs interactive mode */
1620 if (method->batch_flag != NULL && *method->batch_flag != 0)
1621 return 0;
1622 return 1;
1623 }
1624
1625 static Authmethod *
authmethod_lookup(const char * name)1626 authmethod_lookup(const char *name)
1627 {
1628 Authmethod *method = NULL;
1629 if (name != NULL)
1630 for (method = authmethods; method->name != NULL; method++)
1631 if (strcmp(name, method->name) == 0)
1632 return method;
1633 debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
1634 return NULL;
1635 }
1636
1637 /* XXX internal state */
1638 static Authmethod *current = NULL;
1639 static char *supported = NULL;
1640 static char *preferred = NULL;
1641
1642 /*
1643 * Given the authentication method list sent by the server, return the
1644 * next method we should try. If the server initially sends a nil list,
1645 * use a built-in default list.
1646 */
1647 static Authmethod *
authmethod_get(char * authlist)1648 authmethod_get(char *authlist)
1649 {
1650 char *name = NULL;
1651 u_int next;
1652
1653 /* Use a suitable default if we're passed a nil list. */
1654 if (authlist == NULL || strlen(authlist) == 0)
1655 authlist = options.preferred_authentications;
1656
1657 if (supported == NULL || strcmp(authlist, supported) != 0) {
1658 debug3("start over, passed a different list %s", authlist);
1659 free(supported);
1660 supported = xstrdup(authlist);
1661 preferred = options.preferred_authentications;
1662 debug3("preferred %s", preferred);
1663 current = NULL;
1664 } else if (current != NULL && authmethod_is_enabled(current))
1665 return current;
1666
1667 for (;;) {
1668 if ((name = match_list(preferred, supported, &next)) == NULL) {
1669 debug("No more authentication methods to try.");
1670 current = NULL;
1671 return NULL;
1672 }
1673 preferred += next;
1674 debug3("authmethod_lookup %s", name);
1675 debug3("remaining preferred: %s", preferred);
1676 if ((current = authmethod_lookup(name)) != NULL &&
1677 authmethod_is_enabled(current)) {
1678 debug3("authmethod_is_enabled %s", name);
1679 debug("Next authentication method: %s", name);
1680 free(name);
1681 return current;
1682 }
1683 free(name);
1684 }
1685 }
1686
1687 static char *
authmethods_get(void)1688 authmethods_get(void)
1689 {
1690 Authmethod *method = NULL;
1691 Buffer b;
1692 char *list;
1693
1694 buffer_init(&b);
1695 for (method = authmethods; method->name != NULL; method++) {
1696 if (authmethod_is_enabled(method)) {
1697 if (buffer_len(&b) > 0)
1698 buffer_append(&b, ",", 1);
1699 buffer_append(&b, method->name, strlen(method->name));
1700 }
1701 }
1702 buffer_append(&b, "\0", 1);
1703 list = xstrdup(buffer_ptr(&b));
1704 buffer_free(&b);
1705 return list;
1706 }
1707
1708