1 /* $OpenBSD: sshconnect2.c,v 1.372 2024/01/08 00:34:34 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 <limits.h>
37 #include <netdb.h>
38 #include <pwd.h>
39 #include <signal.h>
40 #include <stdio.h>
41 #include <string.h>
42 #include <stdarg.h>
43 #include <unistd.h>
44 #if defined(HAVE_STRNVIS) && defined(HAVE_VIS_H) && !defined(BROKEN_STRNVIS)
45 #include <vis.h>
46 #endif
47
48 #include "openbsd-compat/sys-queue.h"
49
50 #include "xmalloc.h"
51 #include "ssh.h"
52 #include "ssh2.h"
53 #include "sshbuf.h"
54 #include "packet.h"
55 #include "compat.h"
56 #include "cipher.h"
57 #include "sshkey.h"
58 #include "kex.h"
59 #include "sshconnect.h"
60 #include "authfile.h"
61 #include "dh.h"
62 #include "authfd.h"
63 #include "log.h"
64 #include "misc.h"
65 #include "readconf.h"
66 #include "match.h"
67 #include "dispatch.h"
68 #include "canohost.h"
69 #include "msg.h"
70 #include "pathnames.h"
71 #include "uidswap.h"
72 #include "hostfile.h"
73 #include "ssherr.h"
74 #include "utf8.h"
75 #include "ssh-sk.h"
76 #include "sk-api.h"
77
78 #ifdef GSSAPI
79 #include "ssh-gss.h"
80 #endif
81
82 /* import */
83 extern char *client_version_string;
84 extern char *server_version_string;
85 extern Options options;
86
87 /*
88 * SSH2 key exchange
89 */
90
91 static char *xxx_host;
92 static struct sockaddr *xxx_hostaddr;
93 static const struct ssh_conn_info *xxx_conn_info;
94
95 static int
verify_host_key_callback(struct sshkey * hostkey,struct ssh * ssh)96 verify_host_key_callback(struct sshkey *hostkey, struct ssh *ssh)
97 {
98 int r;
99
100 if ((r = sshkey_check_rsa_length(hostkey,
101 options.required_rsa_size)) != 0)
102 fatal_r(r, "Bad server host key");
103 if (verify_host_key(xxx_host, xxx_hostaddr, hostkey,
104 xxx_conn_info) == -1)
105 fatal("Host key verification failed.");
106 return 0;
107 }
108
109 /* Returns the first item from a comma-separated algorithm list */
110 static char *
first_alg(const char * algs)111 first_alg(const char *algs)
112 {
113 char *ret, *cp;
114
115 ret = xstrdup(algs);
116 if ((cp = strchr(ret, ',')) != NULL)
117 *cp = '\0';
118 return ret;
119 }
120
121 static char *
order_hostkeyalgs(char * host,struct sockaddr * hostaddr,u_short port,const struct ssh_conn_info * cinfo)122 order_hostkeyalgs(char *host, struct sockaddr *hostaddr, u_short port,
123 const struct ssh_conn_info *cinfo)
124 {
125 char *oavail = NULL, *avail = NULL, *first = NULL, *last = NULL;
126 char *alg = NULL, *hostname = NULL, *ret = NULL, *best = NULL;
127 size_t maxlen;
128 struct hostkeys *hostkeys = NULL;
129 int ktype;
130 u_int i;
131
132 /* Find all hostkeys for this hostname */
133 get_hostfile_hostname_ipaddr(host, hostaddr, port, &hostname, NULL);
134 hostkeys = init_hostkeys();
135 for (i = 0; i < options.num_user_hostfiles; i++)
136 load_hostkeys(hostkeys, hostname, options.user_hostfiles[i], 0);
137 for (i = 0; i < options.num_system_hostfiles; i++) {
138 load_hostkeys(hostkeys, hostname,
139 options.system_hostfiles[i], 0);
140 }
141 if (options.known_hosts_command != NULL) {
142 load_hostkeys_command(hostkeys, options.known_hosts_command,
143 "ORDER", cinfo, NULL, hostname);
144 }
145 /*
146 * If a plain public key exists that matches the type of the best
147 * preference HostkeyAlgorithms, then use the whole list as is.
148 * Note that we ignore whether the best preference algorithm is a
149 * certificate type, as sshconnect.c will downgrade certs to
150 * plain keys if necessary.
151 */
152 best = first_alg(options.hostkeyalgorithms);
153 if (lookup_key_in_hostkeys_by_type(hostkeys,
154 sshkey_type_plain(sshkey_type_from_name(best)),
155 sshkey_ecdsa_nid_from_name(best), NULL)) {
156 debug3_f("have matching best-preference key type %s, "
157 "using HostkeyAlgorithms verbatim", best);
158 ret = xstrdup(options.hostkeyalgorithms);
159 goto out;
160 }
161
162 /*
163 * Otherwise, prefer the host key algorithms that match known keys
164 * while keeping the ordering of HostkeyAlgorithms as much as possible.
165 */
166 oavail = avail = xstrdup(options.hostkeyalgorithms);
167 maxlen = strlen(avail) + 1;
168 first = xmalloc(maxlen);
169 last = xmalloc(maxlen);
170 *first = *last = '\0';
171
172 #define ALG_APPEND(to, from) \
173 do { \
174 if (*to != '\0') \
175 strlcat(to, ",", maxlen); \
176 strlcat(to, from, maxlen); \
177 } while (0)
178
179 while ((alg = strsep(&avail, ",")) && *alg != '\0') {
180 if ((ktype = sshkey_type_from_name(alg)) == KEY_UNSPEC)
181 fatal_f("unknown alg %s", alg);
182 /*
183 * If we have a @cert-authority marker in known_hosts then
184 * prefer all certificate algorithms.
185 */
186 if (sshkey_type_is_cert(ktype) &&
187 lookup_marker_in_hostkeys(hostkeys, MRK_CA)) {
188 ALG_APPEND(first, alg);
189 continue;
190 }
191 /* If the key appears in known_hosts then prefer it */
192 if (lookup_key_in_hostkeys_by_type(hostkeys,
193 sshkey_type_plain(ktype),
194 sshkey_ecdsa_nid_from_name(alg), NULL)) {
195 ALG_APPEND(first, alg);
196 continue;
197 }
198 /* Otherwise, put it last */
199 ALG_APPEND(last, alg);
200 }
201 #undef ALG_APPEND
202 xasprintf(&ret, "%s%s%s", first,
203 (*first == '\0' || *last == '\0') ? "" : ",", last);
204 if (*first != '\0')
205 debug3_f("prefer hostkeyalgs: %s", first);
206 else
207 debug3_f("no algorithms matched; accept original");
208 out:
209 free(best);
210 free(first);
211 free(last);
212 free(hostname);
213 free(oavail);
214 free_hostkeys(hostkeys);
215
216 return ret;
217 }
218
219 void
ssh_kex2(struct ssh * ssh,char * host,struct sockaddr * hostaddr,u_short port,const struct ssh_conn_info * cinfo)220 ssh_kex2(struct ssh *ssh, char *host, struct sockaddr *hostaddr, u_short port,
221 const struct ssh_conn_info *cinfo)
222 {
223 char *myproposal[PROPOSAL_MAX];
224 char *all_key, *hkalgs = NULL;
225 int r, use_known_hosts_order = 0;
226
227 xxx_host = host;
228 xxx_hostaddr = hostaddr;
229 xxx_conn_info = cinfo;
230
231 if (options.rekey_limit || options.rekey_interval)
232 ssh_packet_set_rekey_limits(ssh, options.rekey_limit,
233 options.rekey_interval);
234
235 /*
236 * If the user has not specified HostkeyAlgorithms, or has only
237 * appended or removed algorithms from that list then prefer algorithms
238 * that are in the list that are supported by known_hosts keys.
239 */
240 if (options.hostkeyalgorithms == NULL ||
241 options.hostkeyalgorithms[0] == '-' ||
242 options.hostkeyalgorithms[0] == '+')
243 use_known_hosts_order = 1;
244
245 /* Expand or fill in HostkeyAlgorithms */
246 all_key = sshkey_alg_list(0, 0, 1, ',');
247 if ((r = kex_assemble_names(&options.hostkeyalgorithms,
248 kex_default_pk_alg(), all_key)) != 0)
249 fatal_fr(r, "kex_assemble_namelist");
250 free(all_key);
251
252 if (use_known_hosts_order)
253 hkalgs = order_hostkeyalgs(host, hostaddr, port, cinfo);
254
255 kex_proposal_populate_entries(ssh, myproposal,
256 options.kex_algorithms, options.ciphers, options.macs,
257 compression_alg_list(options.compression),
258 hkalgs ? hkalgs : options.hostkeyalgorithms);
259
260 free(hkalgs);
261
262 /* start key exchange */
263 if ((r = kex_setup(ssh, myproposal)) != 0)
264 fatal_r(r, "kex_setup");
265 #ifdef WITH_OPENSSL
266 ssh->kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_client;
267 ssh->kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_client;
268 ssh->kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_client;
269 ssh->kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_client;
270 ssh->kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_client;
271 ssh->kex->kex[KEX_DH_GEX_SHA1] = kexgex_client;
272 ssh->kex->kex[KEX_DH_GEX_SHA256] = kexgex_client;
273 # ifdef OPENSSL_HAS_ECC
274 ssh->kex->kex[KEX_ECDH_SHA2] = kex_gen_client;
275 # endif
276 #endif
277 ssh->kex->kex[KEX_C25519_SHA256] = kex_gen_client;
278 ssh->kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_client;
279 ssh->kex->verify_host_key=&verify_host_key_callback;
280
281 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &ssh->kex->done);
282 kex_proposal_free_entries(myproposal);
283
284 #ifdef DEBUG_KEXDH
285 /* send 1st encrypted/maced/compressed message */
286 if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
287 (r = sshpkt_put_cstring(ssh, "markus")) != 0 ||
288 (r = sshpkt_send(ssh)) != 0 ||
289 (r = ssh_packet_write_wait(ssh)) != 0)
290 fatal_fr(r, "send packet");
291 #endif
292 }
293
294 /*
295 * Authenticate user
296 */
297
298 typedef struct cauthctxt Authctxt;
299 typedef struct cauthmethod Authmethod;
300 typedef struct identity Identity;
301 typedef struct idlist Idlist;
302
303 struct identity {
304 TAILQ_ENTRY(identity) next;
305 int agent_fd; /* >=0 if agent supports key */
306 struct sshkey *key; /* public/private key */
307 char *filename; /* comment for agent-only keys */
308 int tried;
309 int isprivate; /* key points to the private key */
310 int userprovided;
311 };
312 TAILQ_HEAD(idlist, identity);
313
314 struct cauthctxt {
315 const char *server_user;
316 const char *local_user;
317 const char *host;
318 const char *service;
319 struct cauthmethod *method;
320 sig_atomic_t success;
321 char *authlist;
322 #ifdef GSSAPI
323 /* gssapi */
324 gss_OID_set gss_supported_mechs;
325 u_int mech_tried;
326 #endif
327 /* pubkey */
328 struct idlist keys;
329 int agent_fd;
330 /* hostbased */
331 Sensitive *sensitive;
332 char *oktypes, *ktypes;
333 const char *active_ktype;
334 /* kbd-interactive */
335 int info_req_seen;
336 int attempt_kbdint;
337 /* password */
338 int attempt_passwd;
339 /* generic */
340 void *methoddata;
341 };
342
343 struct cauthmethod {
344 char *name; /* string to compare against server's list */
345 int (*userauth)(struct ssh *ssh);
346 void (*cleanup)(struct ssh *ssh);
347 int *enabled; /* flag in option struct that enables method */
348 int *batch_flag; /* flag in option struct that disables method */
349 };
350
351 static int input_userauth_service_accept(int, u_int32_t, struct ssh *);
352 static int input_userauth_success(int, u_int32_t, struct ssh *);
353 static int input_userauth_failure(int, u_int32_t, struct ssh *);
354 static int input_userauth_banner(int, u_int32_t, struct ssh *);
355 static int input_userauth_error(int, u_int32_t, struct ssh *);
356 static int input_userauth_info_req(int, u_int32_t, struct ssh *);
357 static int input_userauth_pk_ok(int, u_int32_t, struct ssh *);
358 static int input_userauth_passwd_changereq(int, u_int32_t, struct ssh *);
359
360 static int userauth_none(struct ssh *);
361 static int userauth_pubkey(struct ssh *);
362 static int userauth_passwd(struct ssh *);
363 static int userauth_kbdint(struct ssh *);
364 static int userauth_hostbased(struct ssh *);
365
366 #ifdef GSSAPI
367 static int userauth_gssapi(struct ssh *);
368 static void userauth_gssapi_cleanup(struct ssh *);
369 static int input_gssapi_response(int type, u_int32_t, struct ssh *);
370 static int input_gssapi_token(int type, u_int32_t, struct ssh *);
371 static int input_gssapi_error(int, u_int32_t, struct ssh *);
372 static int input_gssapi_errtok(int, u_int32_t, struct ssh *);
373 #endif
374
375 void userauth(struct ssh *, char *);
376
377 static void pubkey_cleanup(struct ssh *);
378 static int sign_and_send_pubkey(struct ssh *ssh, Identity *);
379 static void pubkey_prepare(struct ssh *, Authctxt *);
380 static void pubkey_reset(Authctxt *);
381 static struct sshkey *load_identity_file(Identity *);
382
383 static Authmethod *authmethod_get(char *authlist);
384 static Authmethod *authmethod_lookup(const char *name);
385 static char *authmethods_get(void);
386
387 Authmethod authmethods[] = {
388 #ifdef GSSAPI
389 {"gssapi-with-mic",
390 userauth_gssapi,
391 userauth_gssapi_cleanup,
392 &options.gss_authentication,
393 NULL},
394 #endif
395 {"hostbased",
396 userauth_hostbased,
397 NULL,
398 &options.hostbased_authentication,
399 NULL},
400 {"publickey",
401 userauth_pubkey,
402 NULL,
403 &options.pubkey_authentication,
404 NULL},
405 {"keyboard-interactive",
406 userauth_kbdint,
407 NULL,
408 &options.kbd_interactive_authentication,
409 &options.batch_mode},
410 {"password",
411 userauth_passwd,
412 NULL,
413 &options.password_authentication,
414 &options.batch_mode},
415 {"none",
416 userauth_none,
417 NULL,
418 NULL,
419 NULL},
420 {NULL, NULL, NULL, NULL, NULL}
421 };
422
423 void
ssh_userauth2(struct ssh * ssh,const char * local_user,const char * server_user,char * host,Sensitive * sensitive)424 ssh_userauth2(struct ssh *ssh, const char *local_user,
425 const char *server_user, char *host, Sensitive *sensitive)
426 {
427 Authctxt authctxt;
428 int r;
429
430 if (options.preferred_authentications == NULL)
431 options.preferred_authentications = authmethods_get();
432
433 /* setup authentication context */
434 memset(&authctxt, 0, sizeof(authctxt));
435 authctxt.server_user = server_user;
436 authctxt.local_user = local_user;
437 authctxt.host = host;
438 authctxt.service = "ssh-connection"; /* service name */
439 authctxt.success = 0;
440 authctxt.method = authmethod_lookup("none");
441 authctxt.authlist = NULL;
442 authctxt.methoddata = NULL;
443 authctxt.sensitive = sensitive;
444 authctxt.active_ktype = authctxt.oktypes = authctxt.ktypes = NULL;
445 authctxt.info_req_seen = 0;
446 authctxt.attempt_kbdint = 0;
447 authctxt.attempt_passwd = 0;
448 #if GSSAPI
449 authctxt.gss_supported_mechs = NULL;
450 authctxt.mech_tried = 0;
451 #endif
452 authctxt.agent_fd = -1;
453 if (authctxt.method == NULL)
454 fatal_f("internal error: cannot send userauth none request");
455
456 if ((r = sshpkt_start(ssh, SSH2_MSG_SERVICE_REQUEST)) != 0 ||
457 (r = sshpkt_put_cstring(ssh, "ssh-userauth")) != 0 ||
458 (r = sshpkt_send(ssh)) != 0)
459 fatal_fr(r, "send packet");
460
461 ssh->authctxt = &authctxt;
462 ssh_dispatch_init(ssh, &input_userauth_error);
463 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, kex_input_ext_info);
464 ssh_dispatch_set(ssh, SSH2_MSG_SERVICE_ACCEPT, &input_userauth_service_accept);
465 ssh_dispatch_run_fatal(ssh, DISPATCH_BLOCK, &authctxt.success); /* loop until success */
466 pubkey_cleanup(ssh);
467 #ifdef GSSAPI
468 if (authctxt.gss_supported_mechs != NULL) {
469 u_int ms;
470
471 gss_release_oid_set(&ms, &authctxt.gss_supported_mechs);
472 authctxt.gss_supported_mechs = NULL;
473 }
474 #endif
475 ssh->authctxt = NULL;
476
477 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_MIN, SSH2_MSG_USERAUTH_MAX, NULL);
478
479 if (!authctxt.success)
480 fatal("Authentication failed.");
481 if (ssh_packet_connection_is_on_socket(ssh)) {
482 verbose("Authenticated to %s ([%s]:%d) using \"%s\".", host,
483 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh),
484 authctxt.method->name);
485 } else {
486 verbose("Authenticated to %s (via proxy) using \"%s\".", host,
487 authctxt.method->name);
488 }
489 }
490
491 static int
input_userauth_service_accept(int type,u_int32_t seq,struct ssh * ssh)492 input_userauth_service_accept(int type, u_int32_t seq, struct ssh *ssh)
493 {
494 int r;
495
496 if (ssh_packet_remaining(ssh) > 0) {
497 char *reply;
498
499 if ((r = sshpkt_get_cstring(ssh, &reply, NULL)) != 0)
500 goto out;
501 debug2("service_accept: %s", reply);
502 free(reply);
503 } else {
504 debug2("buggy server: service_accept w/o service");
505 }
506 if ((r = sshpkt_get_end(ssh)) != 0)
507 goto out;
508 debug("SSH2_MSG_SERVICE_ACCEPT received");
509
510 /* initial userauth request */
511 userauth_none(ssh);
512
513 /* accept EXT_INFO at any time during userauth */
514 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, ssh->kex->ext_info_s ?
515 &kex_input_ext_info : &input_userauth_error);
516 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_SUCCESS, &input_userauth_success);
517 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_FAILURE, &input_userauth_failure);
518 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_BANNER, &input_userauth_banner);
519 r = 0;
520 out:
521 return r;
522 }
523
524 void
userauth(struct ssh * ssh,char * authlist)525 userauth(struct ssh *ssh, char *authlist)
526 {
527 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
528
529 if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
530 authctxt->method->cleanup(ssh);
531
532 free(authctxt->methoddata);
533 authctxt->methoddata = NULL;
534 if (authlist == NULL) {
535 authlist = authctxt->authlist;
536 } else {
537 free(authctxt->authlist);
538 authctxt->authlist = authlist;
539 }
540 for (;;) {
541 Authmethod *method = authmethod_get(authlist);
542 if (method == NULL)
543 fatal("%s@%s: Permission denied (%s).",
544 authctxt->server_user, authctxt->host, authlist);
545 authctxt->method = method;
546
547 /* reset the per method handler */
548 ssh_dispatch_range(ssh, SSH2_MSG_USERAUTH_PER_METHOD_MIN,
549 SSH2_MSG_USERAUTH_PER_METHOD_MAX, NULL);
550
551 /* and try new method */
552 if (method->userauth(ssh) != 0) {
553 debug2("we sent a %s packet, wait for reply", method->name);
554 break;
555 } else {
556 debug2("we did not send a packet, disable method");
557 method->enabled = NULL;
558 }
559 }
560 }
561
562 static int
input_userauth_error(int type,u_int32_t seq,struct ssh * ssh)563 input_userauth_error(int type, u_int32_t seq, struct ssh *ssh)
564 {
565 fatal_f("bad message during authentication: type %d", type);
566 return 0;
567 }
568
569 static int
input_userauth_banner(int type,u_int32_t seq,struct ssh * ssh)570 input_userauth_banner(int type, u_int32_t seq, struct ssh *ssh)
571 {
572 char *msg = NULL;
573 size_t len;
574 int r;
575
576 debug3_f("entering");
577 if ((r = sshpkt_get_cstring(ssh, &msg, &len)) != 0 ||
578 (r = sshpkt_get_cstring(ssh, NULL, NULL)) != 0)
579 goto out;
580 if (len > 0 && options.log_level >= SYSLOG_LEVEL_INFO)
581 fmprintf(stderr, "%s", msg);
582 r = 0;
583 out:
584 free(msg);
585 return r;
586 }
587
588 static int
input_userauth_success(int type,u_int32_t seq,struct ssh * ssh)589 input_userauth_success(int type, u_int32_t seq, struct ssh *ssh)
590 {
591 Authctxt *authctxt = ssh->authctxt;
592
593 if (authctxt == NULL)
594 fatal_f("no authentication context");
595 free(authctxt->authlist);
596 authctxt->authlist = NULL;
597 if (authctxt->method != NULL && authctxt->method->cleanup != NULL)
598 authctxt->method->cleanup(ssh);
599 free(authctxt->methoddata);
600 authctxt->methoddata = NULL;
601 authctxt->success = 1; /* break out */
602 ssh_dispatch_set(ssh, SSH2_MSG_EXT_INFO, dispatch_protocol_error);
603 return 0;
604 }
605
606 #if 0
607 static int
608 input_userauth_success_unexpected(int type, u_int32_t seq, struct ssh *ssh)
609 {
610 Authctxt *authctxt = ssh->authctxt;
611
612 if (authctxt == NULL)
613 fatal_f("no authentication context");
614
615 fatal("Unexpected authentication success during %s.",
616 authctxt->method->name);
617 return 0;
618 }
619 #endif
620
621 static int
input_userauth_failure(int type,u_int32_t seq,struct ssh * ssh)622 input_userauth_failure(int type, u_int32_t seq, struct ssh *ssh)
623 {
624 Authctxt *authctxt = ssh->authctxt;
625 char *authlist = NULL;
626 u_char partial;
627
628 if (authctxt == NULL)
629 fatal("input_userauth_failure: no authentication context");
630
631 if (sshpkt_get_cstring(ssh, &authlist, NULL) != 0 ||
632 sshpkt_get_u8(ssh, &partial) != 0 ||
633 sshpkt_get_end(ssh) != 0)
634 goto out;
635
636 if (partial != 0) {
637 verbose("Authenticated using \"%s\" with partial success.",
638 authctxt->method->name);
639 /* reset state */
640 pubkey_reset(authctxt);
641 }
642 debug("Authentications that can continue: %s", authlist);
643
644 userauth(ssh, authlist);
645 authlist = NULL;
646 out:
647 free(authlist);
648 return 0;
649 }
650
651 /*
652 * Format an identity for logging including filename, key type, fingerprint
653 * and location (agent, etc.). Caller must free.
654 */
655 static char *
format_identity(Identity * id)656 format_identity(Identity *id)
657 {
658 char *fp = NULL, *ret = NULL;
659 const char *note = "";
660
661 if (id->key != NULL) {
662 fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
663 SSH_FP_DEFAULT);
664 }
665 if (id->key) {
666 if ((id->key->flags & SSHKEY_FLAG_EXT) != 0)
667 note = " token";
668 else if (sshkey_is_sk(id->key))
669 note = " authenticator";
670 }
671 xasprintf(&ret, "%s %s%s%s%s%s%s",
672 id->filename,
673 id->key ? sshkey_type(id->key) : "", id->key ? " " : "",
674 fp ? fp : "",
675 id->userprovided ? " explicit" : "", note,
676 id->agent_fd != -1 ? " agent" : "");
677 free(fp);
678 return ret;
679 }
680
681 static int
input_userauth_pk_ok(int type,u_int32_t seq,struct ssh * ssh)682 input_userauth_pk_ok(int type, u_int32_t seq, struct ssh *ssh)
683 {
684 Authctxt *authctxt = ssh->authctxt;
685 struct sshkey *key = NULL;
686 Identity *id = NULL;
687 int pktype, found = 0, sent = 0;
688 size_t blen;
689 char *pkalg = NULL, *fp = NULL, *ident = NULL;
690 u_char *pkblob = NULL;
691 int r;
692
693 if (authctxt == NULL)
694 fatal("input_userauth_pk_ok: no authentication context");
695
696 if ((r = sshpkt_get_cstring(ssh, &pkalg, NULL)) != 0 ||
697 (r = sshpkt_get_string(ssh, &pkblob, &blen)) != 0 ||
698 (r = sshpkt_get_end(ssh)) != 0)
699 goto done;
700
701 if ((pktype = sshkey_type_from_name(pkalg)) == KEY_UNSPEC) {
702 debug_f("server sent unknown pkalg %s", pkalg);
703 goto done;
704 }
705 if ((r = sshkey_from_blob(pkblob, blen, &key)) != 0) {
706 debug_r(r, "no key from blob. pkalg %s", pkalg);
707 goto done;
708 }
709 if (key->type != pktype) {
710 error("input_userauth_pk_ok: type mismatch "
711 "for decoded key (received %d, expected %d)",
712 key->type, pktype);
713 goto done;
714 }
715
716 /*
717 * search keys in the reverse order, because last candidate has been
718 * moved to the end of the queue. this also avoids confusion by
719 * duplicate keys
720 */
721 TAILQ_FOREACH_REVERSE(id, &authctxt->keys, idlist, next) {
722 if (sshkey_equal(key, id->key)) {
723 found = 1;
724 break;
725 }
726 }
727 if (!found || id == NULL) {
728 fp = sshkey_fingerprint(key, options.fingerprint_hash,
729 SSH_FP_DEFAULT);
730 error_f("server replied with unknown key: %s %s",
731 sshkey_type(key), fp == NULL ? "<ERROR>" : fp);
732 goto done;
733 }
734 ident = format_identity(id);
735 debug("Server accepts key: %s", ident);
736 sent = sign_and_send_pubkey(ssh, id);
737 r = 0;
738 done:
739 sshkey_free(key);
740 free(ident);
741 free(fp);
742 free(pkalg);
743 free(pkblob);
744
745 /* try another method if we did not send a packet */
746 if (r == 0 && sent == 0)
747 userauth(ssh, NULL);
748 return r;
749 }
750
751 #ifdef GSSAPI
752 static int
userauth_gssapi(struct ssh * ssh)753 userauth_gssapi(struct ssh *ssh)
754 {
755 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
756 Gssctxt *gssctxt = NULL;
757 OM_uint32 min;
758 int r, ok = 0;
759 gss_OID mech = NULL;
760
761 /* Try one GSSAPI method at a time, rather than sending them all at
762 * once. */
763
764 if (authctxt->gss_supported_mechs == NULL)
765 gss_indicate_mechs(&min, &authctxt->gss_supported_mechs);
766
767 /* Check to see whether the mechanism is usable before we offer it */
768 while (authctxt->mech_tried < authctxt->gss_supported_mechs->count &&
769 !ok) {
770 mech = &authctxt->gss_supported_mechs->
771 elements[authctxt->mech_tried];
772 /* My DER encoding requires length<128 */
773 if (mech->length < 128 && ssh_gssapi_check_mechanism(&gssctxt,
774 mech, authctxt->host)) {
775 ok = 1; /* Mechanism works */
776 } else {
777 authctxt->mech_tried++;
778 }
779 }
780
781 if (!ok || mech == NULL)
782 return 0;
783
784 authctxt->methoddata=(void *)gssctxt;
785
786 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
787 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
788 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
789 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
790 (r = sshpkt_put_u32(ssh, 1)) != 0 ||
791 (r = sshpkt_put_u32(ssh, (mech->length) + 2)) != 0 ||
792 (r = sshpkt_put_u8(ssh, SSH_GSS_OIDTYPE)) != 0 ||
793 (r = sshpkt_put_u8(ssh, mech->length)) != 0 ||
794 (r = sshpkt_put(ssh, mech->elements, mech->length)) != 0 ||
795 (r = sshpkt_send(ssh)) != 0)
796 fatal_fr(r, "send packet");
797
798 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_RESPONSE, &input_gssapi_response);
799 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_TOKEN, &input_gssapi_token);
800 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERROR, &input_gssapi_error);
801 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_GSSAPI_ERRTOK, &input_gssapi_errtok);
802
803 authctxt->mech_tried++; /* Move along to next candidate */
804
805 return 1;
806 }
807
808 static void
userauth_gssapi_cleanup(struct ssh * ssh)809 userauth_gssapi_cleanup(struct ssh *ssh)
810 {
811 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
812 Gssctxt *gssctxt = (Gssctxt *)authctxt->methoddata;
813
814 ssh_gssapi_delete_ctx(&gssctxt);
815 authctxt->methoddata = NULL;
816 }
817
818 static OM_uint32
process_gssapi_token(struct ssh * ssh,gss_buffer_t recv_tok)819 process_gssapi_token(struct ssh *ssh, gss_buffer_t recv_tok)
820 {
821 Authctxt *authctxt = ssh->authctxt;
822 Gssctxt *gssctxt = authctxt->methoddata;
823 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
824 gss_buffer_desc mic = GSS_C_EMPTY_BUFFER;
825 gss_buffer_desc gssbuf;
826 OM_uint32 status, ms, flags;
827 int r;
828
829 status = ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
830 recv_tok, &send_tok, &flags);
831
832 if (send_tok.length > 0) {
833 u_char type = GSS_ERROR(status) ?
834 SSH2_MSG_USERAUTH_GSSAPI_ERRTOK :
835 SSH2_MSG_USERAUTH_GSSAPI_TOKEN;
836
837 if ((r = sshpkt_start(ssh, type)) != 0 ||
838 (r = sshpkt_put_string(ssh, send_tok.value,
839 send_tok.length)) != 0 ||
840 (r = sshpkt_send(ssh)) != 0)
841 fatal_fr(r, "send %u packet", type);
842
843 gss_release_buffer(&ms, &send_tok);
844 }
845
846 if (status == GSS_S_COMPLETE) {
847 /* send either complete or MIC, depending on mechanism */
848 if (!(flags & GSS_C_INTEG_FLAG)) {
849 if ((r = sshpkt_start(ssh,
850 SSH2_MSG_USERAUTH_GSSAPI_EXCHANGE_COMPLETE)) != 0 ||
851 (r = sshpkt_send(ssh)) != 0)
852 fatal_fr(r, "send completion");
853 } else {
854 struct sshbuf *b;
855
856 if ((b = sshbuf_new()) == NULL)
857 fatal_f("sshbuf_new failed");
858 ssh_gssapi_buildmic(b, authctxt->server_user,
859 authctxt->service, "gssapi-with-mic",
860 ssh->kex->session_id);
861
862 if ((gssbuf.value = sshbuf_mutable_ptr(b)) == NULL)
863 fatal_f("sshbuf_mutable_ptr failed");
864 gssbuf.length = sshbuf_len(b);
865
866 status = ssh_gssapi_sign(gssctxt, &gssbuf, &mic);
867
868 if (!GSS_ERROR(status)) {
869 if ((r = sshpkt_start(ssh,
870 SSH2_MSG_USERAUTH_GSSAPI_MIC)) != 0 ||
871 (r = sshpkt_put_string(ssh, mic.value,
872 mic.length)) != 0 ||
873 (r = sshpkt_send(ssh)) != 0)
874 fatal_fr(r, "send MIC");
875 }
876
877 sshbuf_free(b);
878 gss_release_buffer(&ms, &mic);
879 }
880 }
881
882 return status;
883 }
884
885 static int
input_gssapi_response(int type,u_int32_t plen,struct ssh * ssh)886 input_gssapi_response(int type, u_int32_t plen, struct ssh *ssh)
887 {
888 Authctxt *authctxt = ssh->authctxt;
889 Gssctxt *gssctxt;
890 size_t oidlen;
891 u_char *oidv = NULL;
892 int r;
893
894 if (authctxt == NULL)
895 fatal("input_gssapi_response: no authentication context");
896 gssctxt = authctxt->methoddata;
897
898 /* Setup our OID */
899 if ((r = sshpkt_get_string(ssh, &oidv, &oidlen)) != 0)
900 goto done;
901
902 if (oidlen <= 2 ||
903 oidv[0] != SSH_GSS_OIDTYPE ||
904 oidv[1] != oidlen - 2) {
905 debug("Badly encoded mechanism OID received");
906 userauth(ssh, NULL);
907 goto ok;
908 }
909
910 if (!ssh_gssapi_check_oid(gssctxt, oidv + 2, oidlen - 2))
911 fatal("Server returned different OID than expected");
912
913 if ((r = sshpkt_get_end(ssh)) != 0)
914 goto done;
915
916 if (GSS_ERROR(process_gssapi_token(ssh, GSS_C_NO_BUFFER))) {
917 /* Start again with next method on list */
918 debug("Trying to start again");
919 userauth(ssh, NULL);
920 goto ok;
921 }
922 ok:
923 r = 0;
924 done:
925 free(oidv);
926 return r;
927 }
928
929 static int
input_gssapi_token(int type,u_int32_t plen,struct ssh * ssh)930 input_gssapi_token(int type, u_int32_t plen, struct ssh *ssh)
931 {
932 Authctxt *authctxt = ssh->authctxt;
933 gss_buffer_desc recv_tok;
934 u_char *p = NULL;
935 size_t len;
936 OM_uint32 status;
937 int r;
938
939 if (authctxt == NULL)
940 fatal("input_gssapi_response: no authentication context");
941
942 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
943 (r = sshpkt_get_end(ssh)) != 0)
944 goto out;
945
946 recv_tok.value = p;
947 recv_tok.length = len;
948 status = process_gssapi_token(ssh, &recv_tok);
949
950 /* Start again with the next method in the list */
951 if (GSS_ERROR(status)) {
952 userauth(ssh, NULL);
953 /* ok */
954 }
955 r = 0;
956 out:
957 free(p);
958 return r;
959 }
960
961 static int
input_gssapi_errtok(int type,u_int32_t plen,struct ssh * ssh)962 input_gssapi_errtok(int type, u_int32_t plen, struct ssh *ssh)
963 {
964 Authctxt *authctxt = ssh->authctxt;
965 Gssctxt *gssctxt;
966 gss_buffer_desc send_tok = GSS_C_EMPTY_BUFFER;
967 gss_buffer_desc recv_tok;
968 OM_uint32 ms;
969 u_char *p = NULL;
970 size_t len;
971 int r;
972
973 if (authctxt == NULL)
974 fatal("input_gssapi_response: no authentication context");
975 gssctxt = authctxt->methoddata;
976
977 if ((r = sshpkt_get_string(ssh, &p, &len)) != 0 ||
978 (r = sshpkt_get_end(ssh)) != 0) {
979 free(p);
980 return r;
981 }
982
983 /* Stick it into GSSAPI and see what it says */
984 recv_tok.value = p;
985 recv_tok.length = len;
986 (void)ssh_gssapi_init_ctx(gssctxt, options.gss_deleg_creds,
987 &recv_tok, &send_tok, NULL);
988 free(p);
989 gss_release_buffer(&ms, &send_tok);
990
991 /* Server will be returning a failed packet after this one */
992 return 0;
993 }
994
995 static int
input_gssapi_error(int type,u_int32_t plen,struct ssh * ssh)996 input_gssapi_error(int type, u_int32_t plen, struct ssh *ssh)
997 {
998 char *msg = NULL;
999 char *lang = NULL;
1000 int r;
1001
1002 if ((r = sshpkt_get_u32(ssh, NULL)) != 0 || /* maj */
1003 (r = sshpkt_get_u32(ssh, NULL)) != 0 || /* min */
1004 (r = sshpkt_get_cstring(ssh, &msg, NULL)) != 0 ||
1005 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
1006 goto out;
1007 r = sshpkt_get_end(ssh);
1008 debug("Server GSSAPI Error:\n%s", msg);
1009 out:
1010 free(msg);
1011 free(lang);
1012 return r;
1013 }
1014 #endif /* GSSAPI */
1015
1016 static int
userauth_none(struct ssh * ssh)1017 userauth_none(struct ssh *ssh)
1018 {
1019 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1020 int r;
1021
1022 /* initial userauth request */
1023 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1024 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1025 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1026 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1027 (r = sshpkt_send(ssh)) != 0)
1028 fatal_fr(r, "send packet");
1029 return 1;
1030 }
1031
1032 static int
userauth_passwd(struct ssh * ssh)1033 userauth_passwd(struct ssh *ssh)
1034 {
1035 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1036 char *password, *prompt = NULL;
1037 const char *host = options.host_key_alias ? options.host_key_alias :
1038 authctxt->host;
1039 int r;
1040
1041 if (authctxt->attempt_passwd++ >= options.number_of_password_prompts)
1042 return 0;
1043
1044 if (authctxt->attempt_passwd != 1)
1045 error("Permission denied, please try again.");
1046
1047 xasprintf(&prompt, "%s@%s's password: ", authctxt->server_user, host);
1048 password = read_passphrase(prompt, 0);
1049 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1050 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1051 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1052 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1053 (r = sshpkt_put_u8(ssh, 0)) != 0 ||
1054 (r = sshpkt_put_cstring(ssh, password)) != 0 ||
1055 (r = sshpkt_add_padding(ssh, 64)) != 0 ||
1056 (r = sshpkt_send(ssh)) != 0)
1057 fatal_fr(r, "send packet");
1058
1059 free(prompt);
1060 if (password != NULL)
1061 freezero(password, strlen(password));
1062
1063 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1064 &input_userauth_passwd_changereq);
1065
1066 return 1;
1067 }
1068
1069 /*
1070 * parse PASSWD_CHANGEREQ, prompt user and send SSH2_MSG_USERAUTH_REQUEST
1071 */
1072 static int
input_userauth_passwd_changereq(int type,u_int32_t seqnr,struct ssh * ssh)1073 input_userauth_passwd_changereq(int type, u_int32_t seqnr, struct ssh *ssh)
1074 {
1075 Authctxt *authctxt = ssh->authctxt;
1076 char *info = NULL, *lang = NULL, *password = NULL, *retype = NULL;
1077 char prompt[256];
1078 const char *host;
1079 int r;
1080
1081 debug2("input_userauth_passwd_changereq");
1082
1083 if (authctxt == NULL)
1084 fatal("input_userauth_passwd_changereq: "
1085 "no authentication context");
1086 host = options.host_key_alias ? options.host_key_alias : authctxt->host;
1087
1088 if ((r = sshpkt_get_cstring(ssh, &info, NULL)) != 0 ||
1089 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
1090 goto out;
1091 if (strlen(info) > 0)
1092 logit("%s", info);
1093 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1094 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1095 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1096 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1097 (r = sshpkt_put_u8(ssh, 1)) != 0) /* additional info */
1098 goto out;
1099
1100 snprintf(prompt, sizeof(prompt),
1101 "Enter %.30s@%.128s's old password: ",
1102 authctxt->server_user, host);
1103 password = read_passphrase(prompt, 0);
1104 if ((r = sshpkt_put_cstring(ssh, password)) != 0)
1105 goto out;
1106
1107 freezero(password, strlen(password));
1108 password = NULL;
1109 while (password == NULL) {
1110 snprintf(prompt, sizeof(prompt),
1111 "Enter %.30s@%.128s's new password: ",
1112 authctxt->server_user, host);
1113 password = read_passphrase(prompt, RP_ALLOW_EOF);
1114 if (password == NULL) {
1115 /* bail out */
1116 r = 0;
1117 goto out;
1118 }
1119 snprintf(prompt, sizeof(prompt),
1120 "Retype %.30s@%.128s's new password: ",
1121 authctxt->server_user, host);
1122 retype = read_passphrase(prompt, 0);
1123 if (strcmp(password, retype) != 0) {
1124 freezero(password, strlen(password));
1125 logit("Mismatch; try again, EOF to quit.");
1126 password = NULL;
1127 }
1128 freezero(retype, strlen(retype));
1129 }
1130 if ((r = sshpkt_put_cstring(ssh, password)) != 0 ||
1131 (r = sshpkt_add_padding(ssh, 64)) != 0 ||
1132 (r = sshpkt_send(ssh)) != 0)
1133 goto out;
1134
1135 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ,
1136 &input_userauth_passwd_changereq);
1137 r = 0;
1138 out:
1139 if (password)
1140 freezero(password, strlen(password));
1141 free(info);
1142 free(lang);
1143 return r;
1144 }
1145
1146 /*
1147 * Select an algorithm for publickey signatures.
1148 * Returns algorithm (caller must free) or NULL if no mutual algorithm found.
1149 *
1150 * Call with ssh==NULL to ignore server-sig-algs extension list and
1151 * only attempt with the key's base signature type.
1152 */
1153 static char *
key_sig_algorithm(struct ssh * ssh,const struct sshkey * key)1154 key_sig_algorithm(struct ssh *ssh, const struct sshkey *key)
1155 {
1156 char *allowed, *oallowed, *cp, *tmp, *alg = NULL;
1157 const char *server_sig_algs;
1158
1159 /*
1160 * The signature algorithm will only differ from the key algorithm
1161 * for RSA keys/certs and when the server advertises support for
1162 * newer (SHA2) algorithms.
1163 */
1164 if (ssh == NULL || ssh->kex->server_sig_algs == NULL ||
1165 (key->type != KEY_RSA && key->type != KEY_RSA_CERT) ||
1166 (key->type == KEY_RSA_CERT && (ssh->compat & SSH_BUG_SIGTYPE))) {
1167 /* Filter base key signature alg against our configuration */
1168 return match_list(sshkey_ssh_name(key),
1169 options.pubkey_accepted_algos, NULL);
1170 }
1171
1172 /*
1173 * Workaround OpenSSH 7.4 bug: this version supports RSA/SHA-2 but
1174 * fails to advertise it via SSH2_MSG_EXT_INFO.
1175 */
1176 server_sig_algs = ssh->kex->server_sig_algs;
1177 if (key->type == KEY_RSA && (ssh->compat & SSH_BUG_SIGTYPE74))
1178 server_sig_algs = "rsa-sha2-256,rsa-sha2-512";
1179
1180 /*
1181 * For RSA keys/certs, since these might have a different sig type:
1182 * find the first entry in PubkeyAcceptedAlgorithms of the right type
1183 * that also appears in the supported signature algorithms list from
1184 * the server.
1185 */
1186 oallowed = allowed = xstrdup(options.pubkey_accepted_algos);
1187 while ((cp = strsep(&allowed, ",")) != NULL) {
1188 if (sshkey_type_from_name(cp) != key->type)
1189 continue;
1190 tmp = match_list(sshkey_sigalg_by_name(cp),
1191 server_sig_algs, NULL);
1192 if (tmp != NULL)
1193 alg = xstrdup(cp);
1194 free(tmp);
1195 if (alg != NULL)
1196 break;
1197 }
1198 free(oallowed);
1199 return alg;
1200 }
1201
1202 static int
identity_sign(struct identity * id,u_char ** sigp,size_t * lenp,const u_char * data,size_t datalen,u_int compat,const char * alg)1203 identity_sign(struct identity *id, u_char **sigp, size_t *lenp,
1204 const u_char *data, size_t datalen, u_int compat, const char *alg)
1205 {
1206 struct sshkey *sign_key = NULL, *prv = NULL;
1207 int is_agent = 0, retried = 0, r = SSH_ERR_INTERNAL_ERROR;
1208 struct notifier_ctx *notifier = NULL;
1209 char *fp = NULL, *pin = NULL, *prompt = NULL;
1210
1211 *sigp = NULL;
1212 *lenp = 0;
1213
1214 /* The agent supports this key. */
1215 if (id->key != NULL && id->agent_fd != -1) {
1216 return ssh_agent_sign(id->agent_fd, id->key, sigp, lenp,
1217 data, datalen, alg, compat);
1218 }
1219
1220 /*
1221 * We have already loaded the private key or the private key is
1222 * stored in external hardware.
1223 */
1224 if (id->key != NULL &&
1225 (id->isprivate || (id->key->flags & SSHKEY_FLAG_EXT))) {
1226 sign_key = id->key;
1227 is_agent = 1;
1228 } else {
1229 /* Load the private key from the file. */
1230 if ((prv = load_identity_file(id)) == NULL)
1231 return SSH_ERR_KEY_NOT_FOUND;
1232 if (id->key != NULL && !sshkey_equal_public(prv, id->key)) {
1233 error_f("private key %s contents do not match public",
1234 id->filename);
1235 r = SSH_ERR_KEY_NOT_FOUND;
1236 goto out;
1237 }
1238 sign_key = prv;
1239 }
1240 retry_pin:
1241 /* Prompt for touch for non-agent FIDO keys that request UP */
1242 if (!is_agent && sshkey_is_sk(sign_key) &&
1243 (sign_key->sk_flags & SSH_SK_USER_PRESENCE_REQD)) {
1244 /* XXX should batch mode just skip these? */
1245 if ((fp = sshkey_fingerprint(sign_key,
1246 options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
1247 fatal_f("fingerprint failed");
1248 notifier = notify_start(options.batch_mode,
1249 "Confirm user presence for key %s %s",
1250 sshkey_type(sign_key), fp);
1251 free(fp);
1252 }
1253 if ((r = sshkey_sign(sign_key, sigp, lenp, data, datalen,
1254 alg, options.sk_provider, pin, compat)) != 0) {
1255 debug_fr(r, "sshkey_sign");
1256 if (!retried && pin == NULL && !is_agent &&
1257 sshkey_is_sk(sign_key) &&
1258 r == SSH_ERR_KEY_WRONG_PASSPHRASE) {
1259 notify_complete(notifier, NULL);
1260 notifier = NULL;
1261 xasprintf(&prompt, "Enter PIN for %s key %s: ",
1262 sshkey_type(sign_key), id->filename);
1263 pin = read_passphrase(prompt, 0);
1264 retried = 1;
1265 goto retry_pin;
1266 }
1267 goto out;
1268 }
1269
1270 /*
1271 * PKCS#11 tokens may not support all signature algorithms,
1272 * so check what we get back.
1273 */
1274 if ((r = sshkey_check_sigtype(*sigp, *lenp, alg)) != 0) {
1275 debug_fr(r, "sshkey_check_sigtype");
1276 goto out;
1277 }
1278 /* success */
1279 r = 0;
1280 out:
1281 free(prompt);
1282 if (pin != NULL)
1283 freezero(pin, strlen(pin));
1284 notify_complete(notifier, r == 0 ? "User presence confirmed" : NULL);
1285 sshkey_free(prv);
1286 return r;
1287 }
1288
1289 static int
id_filename_matches(Identity * id,Identity * private_id)1290 id_filename_matches(Identity *id, Identity *private_id)
1291 {
1292 static const char * const suffixes[] = { ".pub", "-cert.pub", NULL };
1293 size_t len = strlen(id->filename), plen = strlen(private_id->filename);
1294 size_t i, slen;
1295
1296 if (strcmp(id->filename, private_id->filename) == 0)
1297 return 1;
1298 for (i = 0; suffixes[i]; i++) {
1299 slen = strlen(suffixes[i]);
1300 if (len > slen && plen == len - slen &&
1301 strcmp(id->filename + (len - slen), suffixes[i]) == 0 &&
1302 memcmp(id->filename, private_id->filename, plen) == 0)
1303 return 1;
1304 }
1305 return 0;
1306 }
1307
1308 static int
sign_and_send_pubkey(struct ssh * ssh,Identity * id)1309 sign_and_send_pubkey(struct ssh *ssh, Identity *id)
1310 {
1311 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1312 struct sshbuf *b = NULL;
1313 Identity *private_id, *sign_id = NULL;
1314 u_char *signature = NULL;
1315 size_t slen = 0, skip = 0;
1316 int r, fallback_sigtype, sent = 0;
1317 char *alg = NULL, *fp = NULL;
1318 const char *loc = "", *method = "publickey";
1319 int hostbound = 0;
1320
1321 /* prefer host-bound pubkey signatures if supported by server */
1322 if ((ssh->kex->flags & KEX_HAS_PUBKEY_HOSTBOUND) != 0 &&
1323 (options.pubkey_authentication & SSH_PUBKEY_AUTH_HBOUND) != 0) {
1324 hostbound = 1;
1325 method = "publickey-hostbound-v00@openssh.com";
1326 }
1327
1328 if ((fp = sshkey_fingerprint(id->key, options.fingerprint_hash,
1329 SSH_FP_DEFAULT)) == NULL)
1330 return 0;
1331
1332 debug3_f("using %s with %s %s", method, sshkey_type(id->key), fp);
1333
1334 /*
1335 * If the key is an certificate, try to find a matching private key
1336 * and use it to complete the signature.
1337 * If no such private key exists, fall back to trying the certificate
1338 * key itself in case it has a private half already loaded.
1339 * This will try to set sign_id to the private key that will perform
1340 * the signature.
1341 */
1342 if (sshkey_is_cert(id->key)) {
1343 TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1344 if (sshkey_equal_public(id->key, private_id->key) &&
1345 id->key->type != private_id->key->type) {
1346 sign_id = private_id;
1347 break;
1348 }
1349 }
1350 /*
1351 * Exact key matches are preferred, but also allow
1352 * filename matches for non-PKCS#11/agent keys that
1353 * didn't load public keys. This supports the case
1354 * of keeping just a private key file and public
1355 * certificate on disk.
1356 */
1357 if (sign_id == NULL &&
1358 !id->isprivate && id->agent_fd == -1 &&
1359 (id->key->flags & SSHKEY_FLAG_EXT) == 0) {
1360 TAILQ_FOREACH(private_id, &authctxt->keys, next) {
1361 if (private_id->key == NULL &&
1362 id_filename_matches(id, private_id)) {
1363 sign_id = private_id;
1364 break;
1365 }
1366 }
1367 }
1368 if (sign_id != NULL) {
1369 debug2_f("using private key \"%s\"%s for "
1370 "certificate", sign_id->filename,
1371 sign_id->agent_fd != -1 ? " from agent" : "");
1372 } else {
1373 debug_f("no separate private key for certificate "
1374 "\"%s\"", id->filename);
1375 }
1376 }
1377
1378 /*
1379 * If the above didn't select another identity to do the signing
1380 * then default to the one we started with.
1381 */
1382 if (sign_id == NULL)
1383 sign_id = id;
1384
1385 /* assemble and sign data */
1386 for (fallback_sigtype = 0; fallback_sigtype <= 1; fallback_sigtype++) {
1387 free(alg);
1388 slen = 0;
1389 signature = NULL;
1390 if ((alg = key_sig_algorithm(fallback_sigtype ? NULL : ssh,
1391 id->key)) == NULL) {
1392 error_f("no mutual signature supported");
1393 goto out;
1394 }
1395 debug3_f("signing using %s %s", alg, fp);
1396
1397 sshbuf_free(b);
1398 if ((b = sshbuf_new()) == NULL)
1399 fatal_f("sshbuf_new failed");
1400 if (ssh->compat & SSH_OLD_SESSIONID) {
1401 if ((r = sshbuf_putb(b, ssh->kex->session_id)) != 0)
1402 fatal_fr(r, "sshbuf_putb");
1403 } else {
1404 if ((r = sshbuf_put_stringb(b,
1405 ssh->kex->session_id)) != 0)
1406 fatal_fr(r, "sshbuf_put_stringb");
1407 }
1408 skip = sshbuf_len(b);
1409 if ((r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1410 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
1411 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
1412 (r = sshbuf_put_cstring(b, method)) != 0 ||
1413 (r = sshbuf_put_u8(b, 1)) != 0 ||
1414 (r = sshbuf_put_cstring(b, alg)) != 0 ||
1415 (r = sshkey_puts(id->key, b)) != 0) {
1416 fatal_fr(r, "assemble signed data");
1417 }
1418 if (hostbound) {
1419 if (ssh->kex->initial_hostkey == NULL) {
1420 fatal_f("internal error: initial hostkey "
1421 "not recorded");
1422 }
1423 if ((r = sshkey_puts(ssh->kex->initial_hostkey, b)) != 0)
1424 fatal_fr(r, "assemble %s hostkey", method);
1425 }
1426 /* generate signature */
1427 r = identity_sign(sign_id, &signature, &slen,
1428 sshbuf_ptr(b), sshbuf_len(b), ssh->compat, alg);
1429 if (r == 0)
1430 break;
1431 else if (r == SSH_ERR_KEY_NOT_FOUND)
1432 goto out; /* soft failure */
1433 else if (r == SSH_ERR_SIGN_ALG_UNSUPPORTED &&
1434 !fallback_sigtype) {
1435 if (sign_id->agent_fd != -1)
1436 loc = "agent ";
1437 else if ((sign_id->key->flags & SSHKEY_FLAG_EXT) != 0)
1438 loc = "token ";
1439 logit("%skey %s %s returned incorrect signature type",
1440 loc, sshkey_type(id->key), fp);
1441 continue;
1442 }
1443 error_fr(r, "signing failed for %s \"%s\"%s",
1444 sshkey_type(sign_id->key), sign_id->filename,
1445 id->agent_fd != -1 ? " from agent" : "");
1446 goto out;
1447 }
1448 if (slen == 0 || signature == NULL) /* shouldn't happen */
1449 fatal_f("no signature");
1450
1451 /* append signature */
1452 if ((r = sshbuf_put_string(b, signature, slen)) != 0)
1453 fatal_fr(r, "append signature");
1454
1455 #ifdef DEBUG_PK
1456 sshbuf_dump(b, stderr);
1457 #endif
1458 /* skip session id and packet type */
1459 if ((r = sshbuf_consume(b, skip + 1)) != 0)
1460 fatal_fr(r, "consume");
1461
1462 /* put remaining data from buffer into packet */
1463 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1464 (r = sshpkt_putb(ssh, b)) != 0 ||
1465 (r = sshpkt_send(ssh)) != 0)
1466 fatal_fr(r, "enqueue request");
1467
1468 /* success */
1469 sent = 1;
1470
1471 out:
1472 free(fp);
1473 free(alg);
1474 sshbuf_free(b);
1475 freezero(signature, slen);
1476 return sent;
1477 }
1478
1479 static int
send_pubkey_test(struct ssh * ssh,Identity * id)1480 send_pubkey_test(struct ssh *ssh, Identity *id)
1481 {
1482 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1483 u_char *blob = NULL;
1484 char *alg = NULL;
1485 size_t bloblen;
1486 u_int have_sig = 0;
1487 int sent = 0, r;
1488
1489 if ((alg = key_sig_algorithm(ssh, id->key)) == NULL) {
1490 debug_f("no mutual signature algorithm");
1491 goto out;
1492 }
1493
1494 if ((r = sshkey_to_blob(id->key, &blob, &bloblen)) != 0) {
1495 /* we cannot handle this key */
1496 debug3_f("cannot handle key");
1497 goto out;
1498 }
1499 /* register callback for USERAUTH_PK_OK message */
1500 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_PK_OK, &input_userauth_pk_ok);
1501
1502 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1503 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1504 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1505 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1506 (r = sshpkt_put_u8(ssh, have_sig)) != 0 ||
1507 (r = sshpkt_put_cstring(ssh, alg)) != 0 ||
1508 (r = sshpkt_put_string(ssh, blob, bloblen)) != 0 ||
1509 (r = sshpkt_send(ssh)) != 0)
1510 fatal_fr(r, "send packet");
1511 sent = 1;
1512
1513 out:
1514 free(alg);
1515 free(blob);
1516 return sent;
1517 }
1518
1519 static struct sshkey *
load_identity_file(Identity * id)1520 load_identity_file(Identity *id)
1521 {
1522 struct sshkey *private = NULL;
1523 char prompt[300], *passphrase, *comment;
1524 int r, quit = 0, i;
1525 struct stat st;
1526
1527 if (stat(id->filename, &st) == -1) {
1528 do_log2(id->userprovided ?
1529 SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_DEBUG3,
1530 "no such identity: %s: %s", id->filename, strerror(errno));
1531 return NULL;
1532 }
1533 snprintf(prompt, sizeof prompt,
1534 "Enter passphrase for key '%.100s': ", id->filename);
1535 for (i = 0; i <= options.number_of_password_prompts; i++) {
1536 if (i == 0)
1537 passphrase = "";
1538 else {
1539 passphrase = read_passphrase(prompt, 0);
1540 if (*passphrase == '\0') {
1541 debug2("no passphrase given, try next key");
1542 free(passphrase);
1543 break;
1544 }
1545 }
1546 switch ((r = sshkey_load_private_type(KEY_UNSPEC, id->filename,
1547 passphrase, &private, &comment))) {
1548 case 0:
1549 break;
1550 case SSH_ERR_KEY_WRONG_PASSPHRASE:
1551 if (options.batch_mode) {
1552 quit = 1;
1553 break;
1554 }
1555 if (i != 0)
1556 debug2("bad passphrase given, try again...");
1557 break;
1558 case SSH_ERR_SYSTEM_ERROR:
1559 if (errno == ENOENT) {
1560 debug2_r(r, "Load key \"%s\"", id->filename);
1561 quit = 1;
1562 break;
1563 }
1564 /* FALLTHROUGH */
1565 default:
1566 error_r(r, "Load key \"%s\"", id->filename);
1567 quit = 1;
1568 break;
1569 }
1570 if (private != NULL && sshkey_is_sk(private) &&
1571 options.sk_provider == NULL) {
1572 debug("key \"%s\" is an authenticator-hosted key, "
1573 "but no provider specified", id->filename);
1574 sshkey_free(private);
1575 private = NULL;
1576 quit = 1;
1577 }
1578 if (!quit && (r = sshkey_check_rsa_length(private,
1579 options.required_rsa_size)) != 0) {
1580 debug_fr(r, "Skipping key %s", id->filename);
1581 sshkey_free(private);
1582 private = NULL;
1583 quit = 1;
1584 }
1585 if (!quit && private != NULL && id->agent_fd == -1 &&
1586 !(id->key && id->isprivate))
1587 maybe_add_key_to_agent(id->filename, private, comment,
1588 passphrase);
1589 if (i > 0)
1590 freezero(passphrase, strlen(passphrase));
1591 free(comment);
1592 if (private != NULL || quit)
1593 break;
1594 }
1595 return private;
1596 }
1597
1598 static int
key_type_allowed_by_config(struct sshkey * key)1599 key_type_allowed_by_config(struct sshkey *key)
1600 {
1601 if (match_pattern_list(sshkey_ssh_name(key),
1602 options.pubkey_accepted_algos, 0) == 1)
1603 return 1;
1604
1605 /* RSA keys/certs might be allowed by alternate signature types */
1606 switch (key->type) {
1607 case KEY_RSA:
1608 if (match_pattern_list("rsa-sha2-512",
1609 options.pubkey_accepted_algos, 0) == 1)
1610 return 1;
1611 if (match_pattern_list("rsa-sha2-256",
1612 options.pubkey_accepted_algos, 0) == 1)
1613 return 1;
1614 break;
1615 case KEY_RSA_CERT:
1616 if (match_pattern_list("rsa-sha2-512-cert-v01@openssh.com",
1617 options.pubkey_accepted_algos, 0) == 1)
1618 return 1;
1619 if (match_pattern_list("rsa-sha2-256-cert-v01@openssh.com",
1620 options.pubkey_accepted_algos, 0) == 1)
1621 return 1;
1622 break;
1623 }
1624 return 0;
1625 }
1626
1627 /* obtain a list of keys from the agent */
1628 static int
get_agent_identities(struct ssh * ssh,int * agent_fdp,struct ssh_identitylist ** idlistp)1629 get_agent_identities(struct ssh *ssh, int *agent_fdp,
1630 struct ssh_identitylist **idlistp)
1631 {
1632 int r, agent_fd;
1633 struct ssh_identitylist *idlist;
1634
1635 if ((r = ssh_get_authentication_socket(&agent_fd)) != 0) {
1636 if (r != SSH_ERR_AGENT_NOT_PRESENT)
1637 debug_fr(r, "ssh_get_authentication_socket");
1638 return r;
1639 }
1640 if ((r = ssh_agent_bind_hostkey(agent_fd, ssh->kex->initial_hostkey,
1641 ssh->kex->session_id, ssh->kex->initial_sig, 0)) == 0)
1642 debug_f("bound agent to hostkey");
1643 else
1644 debug2_fr(r, "ssh_agent_bind_hostkey");
1645
1646 if ((r = ssh_fetch_identitylist(agent_fd, &idlist)) != 0) {
1647 debug_fr(r, "ssh_fetch_identitylist");
1648 close(agent_fd);
1649 return r;
1650 }
1651 /* success */
1652 *agent_fdp = agent_fd;
1653 *idlistp = idlist;
1654 debug_f("agent returned %zu keys", idlist->nkeys);
1655 return 0;
1656 }
1657
1658 /*
1659 * try keys in the following order:
1660 * 1. certificates listed in the config file
1661 * 2. other input certificates
1662 * 3. agent keys that are found in the config file
1663 * 4. other agent keys
1664 * 5. keys that are only listed in the config file
1665 */
1666 static void
pubkey_prepare(struct ssh * ssh,Authctxt * authctxt)1667 pubkey_prepare(struct ssh *ssh, Authctxt *authctxt)
1668 {
1669 struct identity *id, *id2, *tmp;
1670 struct idlist agent, files, *preferred;
1671 struct sshkey *key;
1672 int disallowed, agent_fd = -1, i, r, found;
1673 size_t j;
1674 struct ssh_identitylist *idlist;
1675 char *cp, *ident;
1676
1677 TAILQ_INIT(&agent); /* keys from the agent */
1678 TAILQ_INIT(&files); /* keys from the config file */
1679 preferred = &authctxt->keys;
1680 TAILQ_INIT(preferred); /* preferred order of keys */
1681
1682 /* list of keys stored in the filesystem and PKCS#11 */
1683 for (i = 0; i < options.num_identity_files; i++) {
1684 key = options.identity_keys[i];
1685 if (key && key->cert &&
1686 key->cert->type != SSH2_CERT_TYPE_USER) {
1687 debug_f("ignoring certificate %s: not a user "
1688 "certificate", options.identity_files[i]);
1689 continue;
1690 }
1691 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) {
1692 debug_f("ignoring authenticator-hosted key %s as no "
1693 "SecurityKeyProvider has been specified",
1694 options.identity_files[i]);
1695 continue;
1696 }
1697 options.identity_keys[i] = NULL;
1698 id = xcalloc(1, sizeof(*id));
1699 id->agent_fd = -1;
1700 id->key = key;
1701 id->filename = xstrdup(options.identity_files[i]);
1702 id->userprovided = options.identity_file_userprovided[i];
1703 TAILQ_INSERT_TAIL(&files, id, next);
1704 }
1705 /* list of certificates specified by user */
1706 for (i = 0; i < options.num_certificate_files; i++) {
1707 key = options.certificates[i];
1708 if (!sshkey_is_cert(key) || key->cert == NULL ||
1709 key->cert->type != SSH2_CERT_TYPE_USER) {
1710 debug_f("ignoring certificate %s: not a user "
1711 "certificate", options.identity_files[i]);
1712 continue;
1713 }
1714 if (key && sshkey_is_sk(key) && options.sk_provider == NULL) {
1715 debug_f("ignoring authenticator-hosted key "
1716 "certificate %s as no "
1717 "SecurityKeyProvider has been specified",
1718 options.identity_files[i]);
1719 continue;
1720 }
1721 id = xcalloc(1, sizeof(*id));
1722 id->agent_fd = -1;
1723 id->key = key;
1724 id->filename = xstrdup(options.certificate_files[i]);
1725 id->userprovided = options.certificate_file_userprovided[i];
1726 TAILQ_INSERT_TAIL(preferred, id, next);
1727 }
1728 /* list of keys supported by the agent */
1729 if ((r = get_agent_identities(ssh, &agent_fd, &idlist)) == 0) {
1730 for (j = 0; j < idlist->nkeys; j++) {
1731 if ((r = sshkey_check_rsa_length(idlist->keys[j],
1732 options.required_rsa_size)) != 0) {
1733 debug_fr(r, "ignoring %s agent key",
1734 sshkey_ssh_name(idlist->keys[j]));
1735 continue;
1736 }
1737 found = 0;
1738 TAILQ_FOREACH(id, &files, next) {
1739 /*
1740 * agent keys from the config file are
1741 * preferred
1742 */
1743 if (sshkey_equal(idlist->keys[j], id->key)) {
1744 TAILQ_REMOVE(&files, id, next);
1745 TAILQ_INSERT_TAIL(preferred, id, next);
1746 id->agent_fd = agent_fd;
1747 found = 1;
1748 break;
1749 }
1750 }
1751 if (!found && !options.identities_only) {
1752 id = xcalloc(1, sizeof(*id));
1753 /* XXX "steals" key/comment from idlist */
1754 id->key = idlist->keys[j];
1755 id->filename = idlist->comments[j];
1756 idlist->keys[j] = NULL;
1757 idlist->comments[j] = NULL;
1758 id->agent_fd = agent_fd;
1759 TAILQ_INSERT_TAIL(&agent, id, next);
1760 }
1761 }
1762 ssh_free_identitylist(idlist);
1763 /* append remaining agent keys */
1764 TAILQ_CONCAT(preferred, &agent, next);
1765 authctxt->agent_fd = agent_fd;
1766 }
1767 /* Prefer PKCS11 keys that are explicitly listed */
1768 TAILQ_FOREACH_SAFE(id, &files, next, tmp) {
1769 if (id->key == NULL || (id->key->flags & SSHKEY_FLAG_EXT) == 0)
1770 continue;
1771 found = 0;
1772 TAILQ_FOREACH(id2, &files, next) {
1773 if (id2->key == NULL ||
1774 (id2->key->flags & SSHKEY_FLAG_EXT) != 0)
1775 continue;
1776 if (sshkey_equal(id->key, id2->key)) {
1777 TAILQ_REMOVE(&files, id, next);
1778 TAILQ_INSERT_TAIL(preferred, id, next);
1779 found = 1;
1780 break;
1781 }
1782 }
1783 /* If IdentitiesOnly set and key not found then don't use it */
1784 if (!found && options.identities_only) {
1785 TAILQ_REMOVE(&files, id, next);
1786 freezero(id, sizeof(*id));
1787 }
1788 }
1789 /* append remaining keys from the config file */
1790 TAILQ_CONCAT(preferred, &files, next);
1791 /* finally, filter by PubkeyAcceptedAlgorithms */
1792 TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
1793 disallowed = 0;
1794 cp = NULL;
1795 if (id->key == NULL)
1796 continue;
1797 if (!key_type_allowed_by_config(id->key)) {
1798 debug("Skipping %s key %s - corresponding algorithm "
1799 "not in PubkeyAcceptedAlgorithms",
1800 sshkey_ssh_name(id->key), id->filename);
1801 disallowed = 1;
1802 } else if (ssh->kex->server_sig_algs != NULL &&
1803 (cp = key_sig_algorithm(ssh, id->key)) == NULL) {
1804 debug("Skipping %s key %s - corresponding algorithm "
1805 "not supported by server",
1806 sshkey_ssh_name(id->key), id->filename);
1807 disallowed = 1;
1808 }
1809 free(cp);
1810 if (!disallowed)
1811 continue;
1812 /* remove key */
1813 TAILQ_REMOVE(preferred, id, next);
1814 sshkey_free(id->key);
1815 free(id->filename);
1816 memset(id, 0, sizeof(*id));
1817 }
1818 /* List the keys we plan on using */
1819 TAILQ_FOREACH_SAFE(id, preferred, next, id2) {
1820 ident = format_identity(id);
1821 debug("Will attempt key: %s", ident);
1822 free(ident);
1823 }
1824 debug2_f("done");
1825 }
1826
1827 static void
pubkey_cleanup(struct ssh * ssh)1828 pubkey_cleanup(struct ssh *ssh)
1829 {
1830 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1831 Identity *id;
1832
1833 if (authctxt->agent_fd != -1) {
1834 ssh_close_authentication_socket(authctxt->agent_fd);
1835 authctxt->agent_fd = -1;
1836 }
1837 for (id = TAILQ_FIRST(&authctxt->keys); id;
1838 id = TAILQ_FIRST(&authctxt->keys)) {
1839 TAILQ_REMOVE(&authctxt->keys, id, next);
1840 sshkey_free(id->key);
1841 free(id->filename);
1842 free(id);
1843 }
1844 }
1845
1846 static void
pubkey_reset(Authctxt * authctxt)1847 pubkey_reset(Authctxt *authctxt)
1848 {
1849 Identity *id;
1850
1851 TAILQ_FOREACH(id, &authctxt->keys, next)
1852 id->tried = 0;
1853 }
1854
1855 static int
userauth_pubkey(struct ssh * ssh)1856 userauth_pubkey(struct ssh *ssh)
1857 {
1858 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1859 Identity *id;
1860 int sent = 0;
1861 char *ident;
1862 static int prepared;
1863
1864 if (!prepared) {
1865 pubkey_prepare(ssh, authctxt);
1866 prepared = 1;
1867 }
1868
1869 while ((id = TAILQ_FIRST(&authctxt->keys))) {
1870 if (id->tried++)
1871 return (0);
1872 /* move key to the end of the queue */
1873 TAILQ_REMOVE(&authctxt->keys, id, next);
1874 TAILQ_INSERT_TAIL(&authctxt->keys, id, next);
1875 /*
1876 * send a test message if we have the public key. for
1877 * encrypted keys we cannot do this and have to load the
1878 * private key instead
1879 */
1880 if (id->key != NULL) {
1881 ident = format_identity(id);
1882 debug("Offering public key: %s", ident);
1883 free(ident);
1884 sent = send_pubkey_test(ssh, id);
1885 } else {
1886 debug("Trying private key: %s", id->filename);
1887 id->key = load_identity_file(id);
1888 if (id->key != NULL) {
1889 if (id->key != NULL) {
1890 id->isprivate = 1;
1891 sent = sign_and_send_pubkey(ssh, id);
1892 }
1893 sshkey_free(id->key);
1894 id->key = NULL;
1895 id->isprivate = 0;
1896 }
1897 }
1898 if (sent)
1899 return (sent);
1900 }
1901 return (0);
1902 }
1903
1904 /*
1905 * Send userauth request message specifying keyboard-interactive method.
1906 */
1907 static int
userauth_kbdint(struct ssh * ssh)1908 userauth_kbdint(struct ssh *ssh)
1909 {
1910 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
1911 int r;
1912
1913 if (authctxt->attempt_kbdint++ >= options.number_of_password_prompts)
1914 return 0;
1915 /* disable if no SSH2_MSG_USERAUTH_INFO_REQUEST has been seen */
1916 if (authctxt->attempt_kbdint > 1 && !authctxt->info_req_seen) {
1917 debug3("userauth_kbdint: disable: no info_req_seen");
1918 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, NULL);
1919 return 0;
1920 }
1921
1922 debug2("userauth_kbdint");
1923 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
1924 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
1925 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
1926 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
1927 (r = sshpkt_put_cstring(ssh, "")) != 0 || /* lang */
1928 (r = sshpkt_put_cstring(ssh, options.kbd_interactive_devices ?
1929 options.kbd_interactive_devices : "")) != 0 ||
1930 (r = sshpkt_send(ssh)) != 0)
1931 fatal_fr(r, "send packet");
1932
1933 ssh_dispatch_set(ssh, SSH2_MSG_USERAUTH_INFO_REQUEST, &input_userauth_info_req);
1934 return 1;
1935 }
1936
1937 /*
1938 * parse INFO_REQUEST, prompt user and send INFO_RESPONSE
1939 */
1940 static int
input_userauth_info_req(int type,u_int32_t seq,struct ssh * ssh)1941 input_userauth_info_req(int type, u_int32_t seq, struct ssh *ssh)
1942 {
1943 Authctxt *authctxt = ssh->authctxt;
1944 char *name = NULL, *inst = NULL, *lang = NULL, *prompt = NULL;
1945 char *display_prompt = NULL, *response = NULL;
1946 u_char echo = 0;
1947 u_int num_prompts, i;
1948 int r;
1949
1950 debug2_f("entering");
1951
1952 if (authctxt == NULL)
1953 fatal_f("no authentication context");
1954
1955 authctxt->info_req_seen = 1;
1956
1957 if ((r = sshpkt_get_cstring(ssh, &name, NULL)) != 0 ||
1958 (r = sshpkt_get_cstring(ssh, &inst, NULL)) != 0 ||
1959 (r = sshpkt_get_cstring(ssh, &lang, NULL)) != 0)
1960 goto out;
1961 if (strlen(name) > 0)
1962 logit("%s", name);
1963 if (strlen(inst) > 0)
1964 logit("%s", inst);
1965
1966 if ((r = sshpkt_get_u32(ssh, &num_prompts)) != 0)
1967 goto out;
1968 /*
1969 * Begin to build info response packet based on prompts requested.
1970 * We commit to providing the correct number of responses, so if
1971 * further on we run into a problem that prevents this, we have to
1972 * be sure and clean this up and send a correct error response.
1973 */
1974 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_INFO_RESPONSE)) != 0 ||
1975 (r = sshpkt_put_u32(ssh, num_prompts)) != 0)
1976 goto out;
1977
1978 debug2_f("num_prompts %d", num_prompts);
1979 for (i = 0; i < num_prompts; i++) {
1980 if ((r = sshpkt_get_cstring(ssh, &prompt, NULL)) != 0 ||
1981 (r = sshpkt_get_u8(ssh, &echo)) != 0)
1982 goto out;
1983 if (asmprintf(&display_prompt, INT_MAX, NULL, "(%s@%s) %s",
1984 authctxt->server_user, options.host_key_alias ?
1985 options.host_key_alias : authctxt->host, prompt) == -1)
1986 fatal_f("asmprintf failed");
1987 response = read_passphrase(display_prompt, echo ? RP_ECHO : 0);
1988 if ((r = sshpkt_put_cstring(ssh, response)) != 0)
1989 goto out;
1990 freezero(response, strlen(response));
1991 free(prompt);
1992 free(display_prompt);
1993 display_prompt = response = prompt = NULL;
1994 }
1995 /* done with parsing incoming message. */
1996 if ((r = sshpkt_get_end(ssh)) != 0 ||
1997 (r = sshpkt_add_padding(ssh, 64)) != 0)
1998 goto out;
1999 r = sshpkt_send(ssh);
2000 out:
2001 if (response)
2002 freezero(response, strlen(response));
2003 free(prompt);
2004 free(display_prompt);
2005 free(name);
2006 free(inst);
2007 free(lang);
2008 return r;
2009 }
2010
2011 static int
ssh_keysign(struct ssh * ssh,struct sshkey * key,u_char ** sigp,size_t * lenp,const u_char * data,size_t datalen)2012 ssh_keysign(struct ssh *ssh, struct sshkey *key, u_char **sigp, size_t *lenp,
2013 const u_char *data, size_t datalen)
2014 {
2015 struct sshbuf *b;
2016 struct stat st;
2017 pid_t pid;
2018 int r, to[2], from[2], status;
2019 int sock = ssh_packet_get_connection_in(ssh);
2020 u_char rversion = 0, version = 2;
2021 void (*osigchld)(int);
2022
2023 *sigp = NULL;
2024 *lenp = 0;
2025
2026 if (stat(_PATH_SSH_KEY_SIGN, &st) == -1) {
2027 error_f("not installed: %s", strerror(errno));
2028 return -1;
2029 }
2030 if (fflush(stdout) != 0) {
2031 error_f("fflush: %s", strerror(errno));
2032 return -1;
2033 }
2034 if (pipe(to) == -1) {
2035 error_f("pipe: %s", strerror(errno));
2036 return -1;
2037 }
2038 if (pipe(from) == -1) {
2039 error_f("pipe: %s", strerror(errno));
2040 return -1;
2041 }
2042 if ((pid = fork()) == -1) {
2043 error_f("fork: %s", strerror(errno));
2044 return -1;
2045 }
2046 osigchld = ssh_signal(SIGCHLD, SIG_DFL);
2047 if (pid == 0) {
2048 close(from[0]);
2049 if (dup2(from[1], STDOUT_FILENO) == -1)
2050 fatal_f("dup2: %s", strerror(errno));
2051 close(to[1]);
2052 if (dup2(to[0], STDIN_FILENO) == -1)
2053 fatal_f("dup2: %s", strerror(errno));
2054 close(from[1]);
2055 close(to[0]);
2056
2057 if (dup2(sock, STDERR_FILENO + 1) == -1)
2058 fatal_f("dup2: %s", strerror(errno));
2059 sock = STDERR_FILENO + 1;
2060 if (fcntl(sock, F_SETFD, 0) == -1) /* keep the socket on exec */
2061 debug3_f("fcntl F_SETFD: %s", strerror(errno));
2062 closefrom(sock + 1);
2063
2064 debug3_f("[child] pid=%ld, exec %s",
2065 (long)getpid(), _PATH_SSH_KEY_SIGN);
2066 execl(_PATH_SSH_KEY_SIGN, _PATH_SSH_KEY_SIGN, (char *)NULL);
2067 fatal_f("exec(%s): %s", _PATH_SSH_KEY_SIGN,
2068 strerror(errno));
2069 }
2070 close(from[1]);
2071 close(to[0]);
2072 sock = STDERR_FILENO + 1;
2073
2074 if ((b = sshbuf_new()) == NULL)
2075 fatal_f("sshbuf_new failed");
2076 /* send # of sock, data to be signed */
2077 if ((r = sshbuf_put_u32(b, sock)) != 0 ||
2078 (r = sshbuf_put_string(b, data, datalen)) != 0)
2079 fatal_fr(r, "buffer error");
2080 if (ssh_msg_send(to[1], version, b) == -1)
2081 fatal_f("couldn't send request");
2082 sshbuf_reset(b);
2083 r = ssh_msg_recv(from[0], b);
2084 close(from[0]);
2085 close(to[1]);
2086 if (r < 0) {
2087 error_f("no reply");
2088 goto fail;
2089 }
2090
2091 errno = 0;
2092 while (waitpid(pid, &status, 0) == -1) {
2093 if (errno != EINTR) {
2094 error_f("waitpid %ld: %s", (long)pid, strerror(errno));
2095 goto fail;
2096 }
2097 }
2098 if (!WIFEXITED(status)) {
2099 error_f("exited abnormally");
2100 goto fail;
2101 }
2102 if (WEXITSTATUS(status) != 0) {
2103 error_f("exited with status %d", WEXITSTATUS(status));
2104 goto fail;
2105 }
2106 if ((r = sshbuf_get_u8(b, &rversion)) != 0) {
2107 error_fr(r, "buffer error");
2108 goto fail;
2109 }
2110 if (rversion != version) {
2111 error_f("bad version");
2112 goto fail;
2113 }
2114 if ((r = sshbuf_get_string(b, sigp, lenp)) != 0) {
2115 error_fr(r, "buffer error");
2116 fail:
2117 ssh_signal(SIGCHLD, osigchld);
2118 sshbuf_free(b);
2119 return -1;
2120 }
2121 ssh_signal(SIGCHLD, osigchld);
2122 sshbuf_free(b);
2123
2124 return 0;
2125 }
2126
2127 static int
userauth_hostbased(struct ssh * ssh)2128 userauth_hostbased(struct ssh *ssh)
2129 {
2130 Authctxt *authctxt = (Authctxt *)ssh->authctxt;
2131 struct sshkey *private = NULL;
2132 struct sshbuf *b = NULL;
2133 u_char *sig = NULL, *keyblob = NULL;
2134 char *fp = NULL, *chost = NULL, *lname = NULL;
2135 size_t siglen = 0, keylen = 0;
2136 int i, r, success = 0;
2137
2138 if (authctxt->ktypes == NULL) {
2139 authctxt->oktypes = xstrdup(options.hostbased_accepted_algos);
2140 authctxt->ktypes = authctxt->oktypes;
2141 }
2142
2143 /*
2144 * Work through each listed type pattern in HostbasedAcceptedAlgorithms,
2145 * trying each hostkey that matches the type in turn.
2146 */
2147 for (;;) {
2148 if (authctxt->active_ktype == NULL)
2149 authctxt->active_ktype = strsep(&authctxt->ktypes, ",");
2150 if (authctxt->active_ktype == NULL ||
2151 *authctxt->active_ktype == '\0')
2152 break;
2153 debug3_f("trying key type %s", authctxt->active_ktype);
2154
2155 /* check for a useful key */
2156 private = NULL;
2157 for (i = 0; i < authctxt->sensitive->nkeys; i++) {
2158 if (authctxt->sensitive->keys[i] == NULL ||
2159 authctxt->sensitive->keys[i]->type == KEY_UNSPEC)
2160 continue;
2161 if (!sshkey_match_keyname_to_sigalgs(
2162 sshkey_ssh_name(authctxt->sensitive->keys[i]),
2163 authctxt->active_ktype))
2164 continue;
2165 /* we take and free the key */
2166 private = authctxt->sensitive->keys[i];
2167 authctxt->sensitive->keys[i] = NULL;
2168 break;
2169 }
2170 /* Found one */
2171 if (private != NULL)
2172 break;
2173 /* No more keys of this type; advance */
2174 authctxt->active_ktype = NULL;
2175 }
2176 if (private == NULL) {
2177 free(authctxt->oktypes);
2178 authctxt->oktypes = authctxt->ktypes = NULL;
2179 authctxt->active_ktype = NULL;
2180 debug("No more client hostkeys for hostbased authentication.");
2181 goto out;
2182 }
2183
2184 if ((fp = sshkey_fingerprint(private, options.fingerprint_hash,
2185 SSH_FP_DEFAULT)) == NULL) {
2186 error_f("sshkey_fingerprint failed");
2187 goto out;
2188 }
2189 debug_f("trying hostkey %s %s using sigalg %s",
2190 sshkey_ssh_name(private), fp, authctxt->active_ktype);
2191
2192 /* figure out a name for the client host */
2193 lname = get_local_name(ssh_packet_get_connection_in(ssh));
2194 if (lname == NULL) {
2195 error_f("cannot get local ipaddr/name");
2196 goto out;
2197 }
2198
2199 /* XXX sshbuf_put_stringf? */
2200 xasprintf(&chost, "%s.", lname);
2201 debug2_f("chost %s", chost);
2202
2203 /* construct data */
2204 if ((b = sshbuf_new()) == NULL) {
2205 error_f("sshbuf_new failed");
2206 goto out;
2207 }
2208 if ((r = sshkey_to_blob(private, &keyblob, &keylen)) != 0) {
2209 error_fr(r, "sshkey_to_blob");
2210 goto out;
2211 }
2212 if ((r = sshbuf_put_stringb(b, ssh->kex->session_id)) != 0 ||
2213 (r = sshbuf_put_u8(b, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
2214 (r = sshbuf_put_cstring(b, authctxt->server_user)) != 0 ||
2215 (r = sshbuf_put_cstring(b, authctxt->service)) != 0 ||
2216 (r = sshbuf_put_cstring(b, authctxt->method->name)) != 0 ||
2217 (r = sshbuf_put_cstring(b, authctxt->active_ktype)) != 0 ||
2218 (r = sshbuf_put_string(b, keyblob, keylen)) != 0 ||
2219 (r = sshbuf_put_cstring(b, chost)) != 0 ||
2220 (r = sshbuf_put_cstring(b, authctxt->local_user)) != 0) {
2221 error_fr(r, "buffer error");
2222 goto out;
2223 }
2224
2225 #ifdef DEBUG_PK
2226 sshbuf_dump(b, stderr);
2227 #endif
2228 if ((r = ssh_keysign(ssh, private, &sig, &siglen,
2229 sshbuf_ptr(b), sshbuf_len(b))) != 0) {
2230 error("sign using hostkey %s %s failed",
2231 sshkey_ssh_name(private), fp);
2232 goto out;
2233 }
2234 if ((r = sshpkt_start(ssh, SSH2_MSG_USERAUTH_REQUEST)) != 0 ||
2235 (r = sshpkt_put_cstring(ssh, authctxt->server_user)) != 0 ||
2236 (r = sshpkt_put_cstring(ssh, authctxt->service)) != 0 ||
2237 (r = sshpkt_put_cstring(ssh, authctxt->method->name)) != 0 ||
2238 (r = sshpkt_put_cstring(ssh, authctxt->active_ktype)) != 0 ||
2239 (r = sshpkt_put_string(ssh, keyblob, keylen)) != 0 ||
2240 (r = sshpkt_put_cstring(ssh, chost)) != 0 ||
2241 (r = sshpkt_put_cstring(ssh, authctxt->local_user)) != 0 ||
2242 (r = sshpkt_put_string(ssh, sig, siglen)) != 0 ||
2243 (r = sshpkt_send(ssh)) != 0) {
2244 error_fr(r, "packet error");
2245 goto out;
2246 }
2247 success = 1;
2248
2249 out:
2250 if (sig != NULL)
2251 freezero(sig, siglen);
2252 free(keyblob);
2253 free(lname);
2254 free(fp);
2255 free(chost);
2256 sshkey_free(private);
2257 sshbuf_free(b);
2258
2259 return success;
2260 }
2261
2262 /* find auth method */
2263
2264 /*
2265 * given auth method name, if configurable options permit this method fill
2266 * in auth_ident field and return true, otherwise return false.
2267 */
2268 static int
authmethod_is_enabled(Authmethod * method)2269 authmethod_is_enabled(Authmethod *method)
2270 {
2271 if (method == NULL)
2272 return 0;
2273 /* return false if options indicate this method is disabled */
2274 if (method->enabled == NULL || *method->enabled == 0)
2275 return 0;
2276 /* return false if batch mode is enabled but method needs interactive mode */
2277 if (method->batch_flag != NULL && *method->batch_flag != 0)
2278 return 0;
2279 return 1;
2280 }
2281
2282 static Authmethod *
authmethod_lookup(const char * name)2283 authmethod_lookup(const char *name)
2284 {
2285 Authmethod *method = NULL;
2286 if (name != NULL)
2287 for (method = authmethods; method->name != NULL; method++)
2288 if (strcmp(name, method->name) == 0)
2289 return method;
2290 debug2("Unrecognized authentication method name: %s", name ? name : "NULL");
2291 return NULL;
2292 }
2293
2294 /* XXX internal state */
2295 static Authmethod *current = NULL;
2296 static char *supported = NULL;
2297 static char *preferred = NULL;
2298
2299 /*
2300 * Given the authentication method list sent by the server, return the
2301 * next method we should try. If the server initially sends a nil list,
2302 * use a built-in default list.
2303 */
2304 static Authmethod *
authmethod_get(char * authlist)2305 authmethod_get(char *authlist)
2306 {
2307 char *name = NULL;
2308 u_int next;
2309
2310 /* Use a suitable default if we're passed a nil list. */
2311 if (authlist == NULL || strlen(authlist) == 0)
2312 authlist = options.preferred_authentications;
2313
2314 if (supported == NULL || strcmp(authlist, supported) != 0) {
2315 debug3("start over, passed a different list %s", authlist);
2316 free(supported);
2317 supported = xstrdup(authlist);
2318 preferred = options.preferred_authentications;
2319 debug3("preferred %s", preferred);
2320 current = NULL;
2321 } else if (current != NULL && authmethod_is_enabled(current))
2322 return current;
2323
2324 for (;;) {
2325 if ((name = match_list(preferred, supported, &next)) == NULL) {
2326 debug("No more authentication methods to try.");
2327 current = NULL;
2328 return NULL;
2329 }
2330 preferred += next;
2331 debug3("authmethod_lookup %s", name);
2332 debug3("remaining preferred: %s", preferred);
2333 if ((current = authmethod_lookup(name)) != NULL &&
2334 authmethod_is_enabled(current)) {
2335 debug3("authmethod_is_enabled %s", name);
2336 debug("Next authentication method: %s", name);
2337 free(name);
2338 return current;
2339 }
2340 free(name);
2341 }
2342 }
2343
2344 static char *
authmethods_get(void)2345 authmethods_get(void)
2346 {
2347 Authmethod *method = NULL;
2348 struct sshbuf *b;
2349 char *list;
2350 int r;
2351
2352 if ((b = sshbuf_new()) == NULL)
2353 fatal_f("sshbuf_new failed");
2354 for (method = authmethods; method->name != NULL; method++) {
2355 if (authmethod_is_enabled(method)) {
2356 if ((r = sshbuf_putf(b, "%s%s",
2357 sshbuf_len(b) ? "," : "", method->name)) != 0)
2358 fatal_fr(r, "buffer error");
2359 }
2360 }
2361 if ((list = sshbuf_dup_string(b)) == NULL)
2362 fatal_f("sshbuf_dup_string failed");
2363 sshbuf_free(b);
2364 return list;
2365 }
2366