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inet6: only mark autoconf addresses tentative if detached
[dragonfly.git] / crypto / openssh / ssh-agent.c
blob006ddad94ae11f6d328a5f2c92096a850ad627b9
1 /* $OpenBSD: ssh-agent.c,v 1.292 2022/09/17 10:11:29 djm Exp $ */
2 /*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * All rights reserved
6 * The authentication agent program.
7 *
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose. Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
13 *
14 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
19 * 1. Redistributions of source code must retain the above copyright
20 * notice, this list of conditions and the following disclaimer.
21 * 2. Redistributions in binary form must reproduce the above copyright
22 * notice, this list of conditions and the following disclaimer in the
23 * documentation and/or other materials provided with the distribution.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
28 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
29 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
30 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
31 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
34 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35 */
36
37 #include "includes.h"
38
39 #include <sys/types.h>
40 #include <sys/resource.h>
41 #include <sys/stat.h>
42 #include <sys/socket.h>
43 #include <sys/wait.h>
44 #ifdef HAVE_SYS_TIME_H
45 # include <sys/time.h>
46 #endif
47 #ifdef HAVE_SYS_UN_H
48 # include <sys/un.h>
49 #endif
50 #include "openbsd-compat/sys-queue.h"
51
52 #ifdef WITH_OPENSSL
53 #include <openssl/evp.h>
54 #include "openbsd-compat/openssl-compat.h"
55 #endif
56
57 #include <errno.h>
58 #include <fcntl.h>
59 #include <limits.h>
60 #ifdef HAVE_PATHS_H
61 # include <paths.h>
62 #endif
63 #ifdef HAVE_POLL_H
64 # include <poll.h>
65 #endif
66 #include <signal.h>
67 #include <stdarg.h>
68 #include <stdio.h>
69 #include <stdlib.h>
70 #include <time.h>
71 #include <string.h>
72 #include <unistd.h>
73 #ifdef HAVE_UTIL_H
74 # include <util.h>
75 #endif
76
77 #include "xmalloc.h"
78 #include "ssh.h"
79 #include "ssh2.h"
80 #include "sshbuf.h"
81 #include "sshkey.h"
82 #include "authfd.h"
83 #include "compat.h"
84 #include "log.h"
85 #include "misc.h"
86 #include "digest.h"
87 #include "ssherr.h"
88 #include "match.h"
89 #include "msg.h"
90 #include "ssherr.h"
91 #include "pathnames.h"
92 #include "ssh-pkcs11.h"
93 #include "sk-api.h"
94 #include "myproposal.h"
95
96 #ifndef DEFAULT_ALLOWED_PROVIDERS
97 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/local/lib*/*"
98 #endif
99
100 /* Maximum accepted message length */
101 #define AGENT_MAX_LEN (256*1024)
102 /* Maximum bytes to read from client socket */
103 #define AGENT_RBUF_LEN (4096)
104 /* Maximum number of recorded session IDs/hostkeys per connection */
105 #define AGENT_MAX_SESSION_IDS 16
106 /* Maximum size of session ID */
107 #define AGENT_MAX_SID_LEN 128
108 /* Maximum number of destination constraints to accept on a key */
109 #define AGENT_MAX_DEST_CONSTRAINTS 1024
110
111 /* XXX store hostkey_sid in a refcounted tree */
112
113 typedef enum {
114 AUTH_UNUSED = 0,
115 AUTH_SOCKET = 1,
116 AUTH_CONNECTION = 2,
117 } sock_type;
118
119 struct hostkey_sid {
120 struct sshkey *key;
121 struct sshbuf *sid;
122 int forwarded;
123 };
124
125 typedef struct socket_entry {
126 int fd;
127 sock_type type;
128 struct sshbuf *input;
129 struct sshbuf *output;
130 struct sshbuf *request;
131 size_t nsession_ids;
132 struct hostkey_sid *session_ids;
133 } SocketEntry;
134
135 u_int sockets_alloc = 0;
136 SocketEntry *sockets = NULL;
137
138 typedef struct identity {
139 TAILQ_ENTRY(identity) next;
140 struct sshkey *key;
141 char *comment;
142 char *provider;
143 time_t death;
144 u_int confirm;
145 char *sk_provider;
146 struct dest_constraint *dest_constraints;
147 size_t ndest_constraints;
148 } Identity;
149
150 struct idtable {
151 int nentries;
152 TAILQ_HEAD(idqueue, identity) idlist;
153 };
154
155 /* private key table */
156 struct idtable *idtab;
157
158 int max_fd = 0;
159
160 /* pid of shell == parent of agent */
161 pid_t parent_pid = -1;
162 time_t parent_alive_interval = 0;
163
164 /* pid of process for which cleanup_socket is applicable */
165 pid_t cleanup_pid = 0;
166
167 /* pathname and directory for AUTH_SOCKET */
168 char socket_name[PATH_MAX];
169 char socket_dir[PATH_MAX];
170
171 /* Pattern-list of allowed PKCS#11/Security key paths */
172 static char *allowed_providers;
173
174 /* locking */
175 #define LOCK_SIZE 32
176 #define LOCK_SALT_SIZE 16
177 #define LOCK_ROUNDS 1
178 int locked = 0;
179 u_char lock_pwhash[LOCK_SIZE];
180 u_char lock_salt[LOCK_SALT_SIZE];
181
182 extern char *__progname;
183
184 /* Default lifetime in seconds (0 == forever) */
185 static int lifetime = 0;
186
187 static int fingerprint_hash = SSH_FP_HASH_DEFAULT;
188
189 /* Refuse signing of non-SSH messages for web-origin FIDO keys */
190 static int restrict_websafe = 1;
191
192 static void
193 close_socket(SocketEntry *e)
194 {
195 size_t i;
196
197 close(e->fd);
198 sshbuf_free(e->input);
199 sshbuf_free(e->output);
200 sshbuf_free(e->request);
201 for (i = 0; i < e->nsession_ids; i++) {
202 sshkey_free(e->session_ids[i].key);
203 sshbuf_free(e->session_ids[i].sid);
204 }
205 free(e->session_ids);
206 memset(e, '\0', sizeof(*e));
207 e->fd = -1;
208 e->type = AUTH_UNUSED;
209 }
210
211 static void
212 idtab_init(void)
213 {
214 idtab = xcalloc(1, sizeof(*idtab));
215 TAILQ_INIT(&idtab->idlist);
216 idtab->nentries = 0;
217 }
218
219 static void
220 free_dest_constraint_hop(struct dest_constraint_hop *dch)
221 {
222 u_int i;
223
224 if (dch == NULL)
225 return;
226 free(dch->user);
227 free(dch->hostname);
228 for (i = 0; i < dch->nkeys; i++)
229 sshkey_free(dch->keys[i]);
230 free(dch->keys);
231 free(dch->key_is_ca);
232 }
233
234 static void
235 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs)
236 {
237 size_t i;
238
239 for (i = 0; i < ndcs; i++) {
240 free_dest_constraint_hop(&dcs[i].from);
241 free_dest_constraint_hop(&dcs[i].to);
242 }
243 free(dcs);
244 }
245
246 static void
247 free_identity(Identity *id)
248 {
249 sshkey_free(id->key);
250 free(id->provider);
251 free(id->comment);
252 free(id->sk_provider);
253 free_dest_constraints(id->dest_constraints, id->ndest_constraints);
254 free(id);
255 }
256
257 /*
258 * Match 'key' against the key/CA list in a destination constraint hop
259 * Returns 0 on success or -1 otherwise.
260 */
261 static int
262 match_key_hop(const char *tag, const struct sshkey *key,
263 const struct dest_constraint_hop *dch)
264 {
265 const char *reason = NULL;
266 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)";
267 u_int i;
268 char *fp;
269
270 if (key == NULL)
271 return -1;
272 /* XXX logspam */
273 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT,
274 SSH_FP_DEFAULT)) == NULL)
275 fatal_f("fingerprint failed");
276 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail",
277 tag, hostname, sshkey_type(key), fp, dch->nkeys);
278 free(fp);
279 for (i = 0; i < dch->nkeys; i++) {
280 if (dch->keys[i] == NULL)
281 return -1;
282 /* XXX logspam */
283 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT,
284 SSH_FP_DEFAULT)) == NULL)
285 fatal_f("fingerprint failed");
286 debug3_f("%s: key %u: %s%s %s", tag, i,
287 dch->key_is_ca[i] ? "CA " : "",
288 sshkey_type(dch->keys[i]), fp);
289 free(fp);
290 if (!sshkey_is_cert(key)) {
291 /* plain key */
292 if (dch->key_is_ca[i] ||
293 !sshkey_equal(key, dch->keys[i]))
294 continue;
295 return 0;
296 }
297 /* certificate */
298 if (!dch->key_is_ca[i])
299 continue;
300 if (key->cert == NULL || key->cert->signature_key == NULL)
301 return -1; /* shouldn't happen */
302 if (!sshkey_equal(key->cert->signature_key, dch->keys[i]))
303 continue;
304 if (sshkey_cert_check_host(key, hostname, 1,
305 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) {
306 debug_f("cert %s / hostname %s rejected: %s",
307 key->cert->key_id, hostname, reason);
308 continue;
309 }
310 return 0;
311 }
312 return -1;
313 }
314
315 /* Check destination constraints on an identity against the hostkey/user */
316 static int
317 permitted_by_dest_constraints(const struct sshkey *fromkey,
318 const struct sshkey *tokey, Identity *id, const char *user,
319 const char **hostnamep)
320 {
321 size_t i;
322 struct dest_constraint *d;
323
324 if (hostnamep != NULL)
325 *hostnamep = NULL;
326 for (i = 0; i < id->ndest_constraints; i++) {
327 d = id->dest_constraints + i;
328 /* XXX remove logspam */
329 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)",
330 i, d->from.user ? d->from.user : "",
331 d->from.user ? "@" : "",
332 d->from.hostname ? d->from.hostname : "(ORIGIN)",
333 d->from.nkeys,
334 d->to.user ? d->to.user : "", d->to.user ? "@" : "",
335 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys);
336
337 /* Match 'from' key */
338 if (fromkey == NULL) {
339 /* We are matching the first hop */
340 if (d->from.hostname != NULL || d->from.nkeys != 0)
341 continue;
342 } else if (match_key_hop("from", fromkey, &d->from) != 0)
343 continue;
344
345 /* Match 'to' key */
346 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0)
347 continue;
348
349 /* Match user if specified */
350 if (d->to.user != NULL && user != NULL &&
351 !match_pattern(user, d->to.user))
352 continue;
353
354 /* successfully matched this constraint */
355 if (hostnamep != NULL)
356 *hostnamep = d->to.hostname;
357 debug2_f("allowed for hostname %s",
358 d->to.hostname == NULL ? "*" : d->to.hostname);
359 return 0;
360 }
361 /* no match */
362 debug2_f("%s identity \"%s\" not permitted for this destination",
363 sshkey_type(id->key), id->comment);
364 return -1;
365 }
366
367 /*
368 * Check whether hostkeys on a SocketEntry and the optionally specified user
369 * are permitted by the destination constraints on the Identity.
370 * Returns 0 on success or -1 otherwise.
371 */
372 static int
373 identity_permitted(Identity *id, SocketEntry *e, char *user,
374 const char **forward_hostnamep, const char **last_hostnamep)
375 {
376 size_t i;
377 const char **hp;
378 struct hostkey_sid *hks;
379 const struct sshkey *fromkey = NULL;
380 const char *test_user;
381 char *fp1, *fp2;
382
383 /* XXX remove logspam */
384 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, "
385 "%zu constraints", sshkey_type(id->key), id->comment,
386 e->nsession_ids, id->ndest_constraints);
387 if (id->ndest_constraints == 0)
388 return 0; /* unconstrained */
389 if (e->nsession_ids == 0)
390 return 0; /* local use */
391 /*
392 * Walk through the hops recorded by session_id and try to find a
393 * constraint that satisfies each.
394 */
395 for (i = 0; i < e->nsession_ids; i++) {
396 hks = e->session_ids + i;
397 if (hks->key == NULL)
398 fatal_f("internal error: no bound key");
399 /* XXX remove logspam */
400 fp1 = fp2 = NULL;
401 if (fromkey != NULL &&
402 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT,
403 SSH_FP_DEFAULT)) == NULL)
404 fatal_f("fingerprint failed");
405 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT,
406 SSH_FP_DEFAULT)) == NULL)
407 fatal_f("fingerprint failed");
408 debug3_f("socketentry fd=%d, entry %zu %s, "
409 "from hostkey %s %s to user %s hostkey %s %s",
410 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH",
411 fromkey ? sshkey_type(fromkey) : "(ORIGIN)",
412 fromkey ? fp1 : "", user ? user : "(ANY)",
413 sshkey_type(hks->key), fp2);
414 free(fp1);
415 free(fp2);
416 /*
417 * Record the hostnames for the initial forwarding and
418 * the final destination.
419 */
420 hp = NULL;
421 if (i == e->nsession_ids - 1)
422 hp = last_hostnamep;
423 else if (i == 0)
424 hp = forward_hostnamep;
425 /* Special handling for final recorded binding */
426 test_user = NULL;
427 if (i == e->nsession_ids - 1) {
428 /* Can only check user at final hop */
429 test_user = user;
430 /*
431 * user is only presented for signature requests.
432 * If this is the case, make sure last binding is not
433 * for a forwarding.
434 */
435 if (hks->forwarded && user != NULL) {
436 error_f("tried to sign on forwarding hop");
437 return -1;
438 }
439 } else if (!hks->forwarded) {
440 error_f("tried to forward though signing bind");
441 return -1;
442 }
443 if (permitted_by_dest_constraints(fromkey, hks->key, id,
444 test_user, hp) != 0)
445 return -1;
446 fromkey = hks->key;
447 }
448 /*
449 * Another special case: if the last bound session ID was for a
450 * forwarding, and this function is not being called to check a sign
451 * request (i.e. no 'user' supplied), then only permit the key if
452 * there is a permission that would allow it to be used at another
453 * destination. This hides keys that are allowed to be used to
454 * authenticate *to* a host but not permitted for *use* beyond it.
455 */
456 hks = &e->session_ids[e->nsession_ids - 1];
457 if (hks->forwarded && user == NULL &&
458 permitted_by_dest_constraints(hks->key, NULL, id,
459 NULL, NULL) != 0) {
460 debug3_f("key permitted at host but not after");
461 return -1;
462 }
463
464 /* success */
465 return 0;
466 }
467
468 /* return matching private key for given public key */
469 static Identity *
470 lookup_identity(struct sshkey *key)
471 {
472 Identity *id;
473
474 TAILQ_FOREACH(id, &idtab->idlist, next) {
475 if (sshkey_equal(key, id->key))
476 return (id);
477 }
478 return (NULL);
479 }
480
481 /* Check confirmation of keysign request */
482 static int
483 confirm_key(Identity *id, const char *extra)
484 {
485 char *p;
486 int ret = -1;
487
488 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT);
489 if (p != NULL &&
490 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s",
491 id->comment, p,
492 extra == NULL ? "" : "\n", extra == NULL ? "" : extra))
493 ret = 0;
494 free(p);
495
496 return (ret);
497 }
498
499 static void
500 send_status(SocketEntry *e, int success)
501 {
502 int r;
503
504 if ((r = sshbuf_put_u32(e->output, 1)) != 0 ||
505 (r = sshbuf_put_u8(e->output, success ?
506 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0)
507 fatal_fr(r, "compose");
508 }
509
510 /* send list of supported public keys to 'client' */
511 static void
512 process_request_identities(SocketEntry *e)
513 {
514 Identity *id;
515 struct sshbuf *msg, *keys;
516 int r;
517 u_int nentries = 0;
518
519 debug2_f("entering");
520
521 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL)
522 fatal_f("sshbuf_new failed");
523 TAILQ_FOREACH(id, &idtab->idlist, next) {
524 /* identity not visible, don't include in response */
525 if (identity_permitted(id, e, NULL, NULL, NULL) != 0)
526 continue;
527 if ((r = sshkey_puts_opts(id->key, keys,
528 SSHKEY_SERIALIZE_INFO)) != 0 ||
529 (r = sshbuf_put_cstring(keys, id->comment)) != 0) {
530 error_fr(r, "compose key/comment");
531 continue;
532 }
533 nentries++;
534 }
535 debug2_f("replying with %u allowed of %u available keys",
536 nentries, idtab->nentries);
537 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
538 (r = sshbuf_put_u32(msg, nentries)) != 0 ||
539 (r = sshbuf_putb(msg, keys)) != 0)
540 fatal_fr(r, "compose");
541 if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
542 fatal_fr(r, "enqueue");
543 sshbuf_free(msg);
544 sshbuf_free(keys);
545 }
546
547
548 static char *
549 agent_decode_alg(struct sshkey *key, u_int flags)
550 {
551 if (key->type == KEY_RSA) {
552 if (flags & SSH_AGENT_RSA_SHA2_256)
553 return "rsa-sha2-256";
554 else if (flags & SSH_AGENT_RSA_SHA2_512)
555 return "rsa-sha2-512";
556 } else if (key->type == KEY_RSA_CERT) {
557 if (flags & SSH_AGENT_RSA_SHA2_256)
558 return "rsa-sha2-256-cert-v01@openssh.com";
559 else if (flags & SSH_AGENT_RSA_SHA2_512)
560 return "rsa-sha2-512-cert-v01@openssh.com";
561 }
562 return NULL;
563 }
564
565 /*
566 * Attempt to parse the contents of a buffer as a SSH publickey userauth
567 * request, checking its contents for consistency and matching the embedded
568 * key against the one that is being used for signing.
569 * Note: does not modify msg buffer.
570 * Optionally extract the username, session ID and/or hostkey from the request.
571 */
572 static int
573 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key,
574 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp)
575 {
576 struct sshbuf *b = NULL, *sess_id = NULL;
577 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL;
578 int r;
579 u_char t, sig_follows;
580 struct sshkey *mkey = NULL, *hostkey = NULL;
581
582 if (userp != NULL)
583 *userp = NULL;
584 if (sess_idp != NULL)
585 *sess_idp = NULL;
586 if (hostkeyp != NULL)
587 *hostkeyp = NULL;
588 if ((b = sshbuf_fromb(msg)) == NULL)
589 fatal_f("sshbuf_fromb");
590
591 /* SSH userauth request */
592 if ((r = sshbuf_froms(b, &sess_id)) != 0)
593 goto out;
594 if (sshbuf_len(sess_id) == 0) {
595 r = SSH_ERR_INVALID_FORMAT;
596 goto out;
597 }
598 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */
599 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */
600 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */
601 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */
602 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */
603 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */
604 (r = sshkey_froms(b, &mkey)) != 0) /* key */
605 goto out;
606 if (t != SSH2_MSG_USERAUTH_REQUEST ||
607 sig_follows != 1 ||
608 strcmp(service, "ssh-connection") != 0 ||
609 !sshkey_equal(expected_key, mkey) ||
610 sshkey_type_from_name(pkalg) != expected_key->type) {
611 r = SSH_ERR_INVALID_FORMAT;
612 goto out;
613 }
614 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) {
615 if ((r = sshkey_froms(b, &hostkey)) != 0)
616 goto out;
617 } else if (strcmp(method, "publickey") != 0) {
618 r = SSH_ERR_INVALID_FORMAT;
619 goto out;
620 }
621 if (sshbuf_len(b) != 0) {
622 r = SSH_ERR_INVALID_FORMAT;
623 goto out;
624 }
625 /* success */
626 r = 0;
627 debug3_f("well formed userauth");
628 if (userp != NULL) {
629 *userp = user;
630 user = NULL;
631 }
632 if (sess_idp != NULL) {
633 *sess_idp = sess_id;
634 sess_id = NULL;
635 }
636 if (hostkeyp != NULL) {
637 *hostkeyp = hostkey;
638 hostkey = NULL;
639 }
640 out:
641 sshbuf_free(b);
642 sshbuf_free(sess_id);
643 free(user);
644 free(service);
645 free(method);
646 free(pkalg);
647 sshkey_free(mkey);
648 sshkey_free(hostkey);
649 return r;
650 }
651
652 /*
653 * Attempt to parse the contents of a buffer as a SSHSIG signature request.
654 * Note: does not modify buffer.
655 */
656 static int
657 parse_sshsig_request(struct sshbuf *msg)
658 {
659 int r;
660 struct sshbuf *b;
661
662 if ((b = sshbuf_fromb(msg)) == NULL)
663 fatal_f("sshbuf_fromb");
664
665 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 ||
666 (r = sshbuf_consume(b, 6)) != 0 ||
667 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */
668 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */
669 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */
670 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */
671 goto out;
672 if (sshbuf_len(b) != 0) {
673 r = SSH_ERR_INVALID_FORMAT;
674 goto out;
675 }
676 /* success */
677 r = 0;
678 out:
679 sshbuf_free(b);
680 return r;
681 }
682
683 /*
684 * This function inspects a message to be signed by a FIDO key that has a
685 * web-like application string (i.e. one that does not begin with "ssh:".
686 * It checks that the message is one of those expected for SSH operations
687 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges
688 * for the web.
689 */
690 static int
691 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data)
692 {
693 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) {
694 debug_f("signed data matches public key userauth request");
695 return 1;
696 }
697 if (parse_sshsig_request(data) == 0) {
698 debug_f("signed data matches SSHSIG signature request");
699 return 1;
700 }
701
702 /* XXX check CA signature operation */
703
704 error("web-origin key attempting to sign non-SSH message");
705 return 0;
706 }
707
708 static int
709 buf_equal(const struct sshbuf *a, const struct sshbuf *b)
710 {
711 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL)
712 return SSH_ERR_INVALID_ARGUMENT;
713 if (sshbuf_len(a) != sshbuf_len(b))
714 return SSH_ERR_INVALID_FORMAT;
715 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0)
716 return SSH_ERR_INVALID_FORMAT;
717 return 0;
718 }
719
720 /* ssh2 only */
721 static void
722 process_sign_request2(SocketEntry *e)
723 {
724 u_char *signature = NULL;
725 size_t slen = 0;
726 u_int compat = 0, flags;
727 int r, ok = -1, retried = 0;
728 char *fp = NULL, *pin = NULL, *prompt = NULL;
729 char *user = NULL, *sig_dest = NULL;
730 const char *fwd_host = NULL, *dest_host = NULL;
731 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL;
732 struct sshkey *key = NULL, *hostkey = NULL;
733 struct identity *id;
734 struct notifier_ctx *notifier = NULL;
735
736 debug_f("entering");
737
738 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL)
739 fatal_f("sshbuf_new failed");
740 if ((r = sshkey_froms(e->request, &key)) != 0 ||
741 (r = sshbuf_get_stringb(e->request, data)) != 0 ||
742 (r = sshbuf_get_u32(e->request, &flags)) != 0) {
743 error_fr(r, "parse");
744 goto send;
745 }
746
747 if ((id = lookup_identity(key)) == NULL) {
748 verbose_f("%s key not found", sshkey_type(key));
749 goto send;
750 }
751 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT,
752 SSH_FP_DEFAULT)) == NULL)
753 fatal_f("fingerprint failed");
754
755 if (id->ndest_constraints != 0) {
756 if (e->nsession_ids == 0) {
757 logit_f("refusing use of destination-constrained key "
758 "to sign on unbound connection");
759 goto send;
760 }
761 if (parse_userauth_request(data, key, &user, &sid,
762 &hostkey) != 0) {
763 logit_f("refusing use of destination-constrained key "
764 "to sign an unidentified signature");
765 goto send;
766 }
767 /* XXX logspam */
768 debug_f("user=%s", user);
769 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0)
770 goto send;
771 /* XXX display fwd_host/dest_host in askpass UI */
772 /*
773 * Ensure that the session ID is the most recent one
774 * registered on the socket - it should have been bound by
775 * ssh immediately before userauth.
776 */
777 if (buf_equal(sid,
778 e->session_ids[e->nsession_ids - 1].sid) != 0) {
779 error_f("unexpected session ID (%zu listed) on "
780 "signature request for target user %s with "
781 "key %s %s", e->nsession_ids, user,
782 sshkey_type(id->key), fp);
783 goto send;
784 }
785 /*
786 * Ensure that the hostkey embedded in the signature matches
787 * the one most recently bound to the socket. An exception is
788 * made for the initial forwarding hop.
789 */
790 if (e->nsession_ids > 1 && hostkey == NULL) {
791 error_f("refusing use of destination-constrained key: "
792 "no hostkey recorded in signature for forwarded "
793 "connection");
794 goto send;
795 }
796 if (hostkey != NULL && !sshkey_equal(hostkey,
797 e->session_ids[e->nsession_ids - 1].key)) {
798 error_f("refusing use of destination-constrained key: "
799 "mismatch between hostkey in request and most "
800 "recently bound session");
801 goto send;
802 }
803 xasprintf(&sig_dest, "public key authentication request for "
804 "user \"%s\" to listed host", user);
805 }
806 if (id->confirm && confirm_key(id, sig_dest) != 0) {
807 verbose_f("user refused key");
808 goto send;
809 }
810 if (sshkey_is_sk(id->key)) {
811 if (restrict_websafe &&
812 strncmp(id->key->sk_application, "ssh:", 4) != 0 &&
813 !check_websafe_message_contents(key, data)) {
814 /* error already logged */
815 goto send;
816 }
817 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) {
818 notifier = notify_start(0,
819 "Confirm user presence for key %s %s%s%s",
820 sshkey_type(id->key), fp,
821 sig_dest == NULL ? "" : "\n",
822 sig_dest == NULL ? "" : sig_dest);
823 }
824 }
825 retry_pin:
826 if ((r = sshkey_sign(id->key, &signature, &slen,
827 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags),
828 id->sk_provider, pin, compat)) != 0) {
829 debug_fr(r, "sshkey_sign");
830 if (pin == NULL && !retried && sshkey_is_sk(id->key) &&
831 r == SSH_ERR_KEY_WRONG_PASSPHRASE) {
832 notify_complete(notifier, NULL);
833 notifier = NULL;
834 /* XXX include sig_dest */
835 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ",
836 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ?
837 " and confirm user presence " : " ",
838 sshkey_type(id->key), fp);
839 pin = read_passphrase(prompt, RP_USE_ASKPASS);
840 retried = 1;
841 goto retry_pin;
842 }
843 error_fr(r, "sshkey_sign");
844 goto send;
845 }
846 /* Success */
847 ok = 0;
848 send:
849 debug_f("good signature");
850 notify_complete(notifier, "User presence confirmed");
851
852 if (ok == 0) {
853 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 ||
854 (r = sshbuf_put_string(msg, signature, slen)) != 0)
855 fatal_fr(r, "compose");
856 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
857 fatal_fr(r, "compose failure");
858
859 if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
860 fatal_fr(r, "enqueue");
861
862 sshbuf_free(sid);
863 sshbuf_free(data);
864 sshbuf_free(msg);
865 sshkey_free(key);
866 sshkey_free(hostkey);
867 free(fp);
868 free(signature);
869 free(sig_dest);
870 free(user);
871 free(prompt);
872 if (pin != NULL)
873 freezero(pin, strlen(pin));
874 }
875
876 /* shared */
877 static void
878 process_remove_identity(SocketEntry *e)
879 {
880 int r, success = 0;
881 struct sshkey *key = NULL;
882 Identity *id;
883
884 debug2_f("entering");
885 if ((r = sshkey_froms(e->request, &key)) != 0) {
886 error_fr(r, "parse key");
887 goto done;
888 }
889 if ((id = lookup_identity(key)) == NULL) {
890 debug_f("key not found");
891 goto done;
892 }
893 /* identity not visible, cannot be removed */
894 if (identity_permitted(id, e, NULL, NULL, NULL) != 0)
895 goto done; /* error already logged */
896 /* We have this key, free it. */
897 if (idtab->nentries < 1)
898 fatal_f("internal error: nentries %d", idtab->nentries);
899 TAILQ_REMOVE(&idtab->idlist, id, next);
900 free_identity(id);
901 idtab->nentries--;
902 success = 1;
903 done:
904 sshkey_free(key);
905 send_status(e, success);
906 }
907
908 static void
909 process_remove_all_identities(SocketEntry *e)
910 {
911 Identity *id;
912
913 debug2_f("entering");
914 /* Loop over all identities and clear the keys. */
915 for (id = TAILQ_FIRST(&idtab->idlist); id;
916 id = TAILQ_FIRST(&idtab->idlist)) {
917 TAILQ_REMOVE(&idtab->idlist, id, next);
918 free_identity(id);
919 }
920
921 /* Mark that there are no identities. */
922 idtab->nentries = 0;
923
924 /* Send success. */
925 send_status(e, 1);
926 }
927
928 /* removes expired keys and returns number of seconds until the next expiry */
929 static time_t
930 reaper(void)
931 {
932 time_t deadline = 0, now = monotime();
933 Identity *id, *nxt;
934
935 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) {
936 nxt = TAILQ_NEXT(id, next);
937 if (id->death == 0)
938 continue;
939 if (now >= id->death) {
940 debug("expiring key '%s'", id->comment);
941 TAILQ_REMOVE(&idtab->idlist, id, next);
942 free_identity(id);
943 idtab->nentries--;
944 } else
945 deadline = (deadline == 0) ? id->death :
946 MINIMUM(deadline, id->death);
947 }
948 if (deadline == 0 || deadline <= now)
949 return 0;
950 else
951 return (deadline - now);
952 }
953
954 static int
955 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch)
956 {
957 u_char key_is_ca;
958 size_t elen = 0;
959 int r;
960 struct sshkey *k = NULL;
961 char *fp;
962
963 memset(dch, '\0', sizeof(*dch));
964 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 ||
965 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 ||
966 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) {
967 error_fr(r, "parse");
968 goto out;
969 }
970 if (elen != 0) {
971 error_f("unsupported extensions (len %zu)", elen);
972 r = SSH_ERR_FEATURE_UNSUPPORTED;
973 goto out;
974 }
975 if (*dch->hostname == '\0') {
976 free(dch->hostname);
977 dch->hostname = NULL;
978 }
979 if (*dch->user == '\0') {
980 free(dch->user);
981 dch->user = NULL;
982 }
983 while (sshbuf_len(b) != 0) {
984 dch->keys = xrecallocarray(dch->keys, dch->nkeys,
985 dch->nkeys + 1, sizeof(*dch->keys));
986 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys,
987 dch->nkeys + 1, sizeof(*dch->key_is_ca));
988 if ((r = sshkey_froms(b, &k)) != 0 ||
989 (r = sshbuf_get_u8(b, &key_is_ca)) != 0)
990 goto out;
991 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT,
992 SSH_FP_DEFAULT)) == NULL)
993 fatal_f("fingerprint failed");
994 debug3_f("%s%s%s: adding %skey %s %s",
995 dch->user == NULL ? "" : dch->user,
996 dch->user == NULL ? "" : "@",
997 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp);
998 free(fp);
999 dch->keys[dch->nkeys] = k;
1000 dch->key_is_ca[dch->nkeys] = key_is_ca != 0;
1001 dch->nkeys++;
1002 k = NULL; /* transferred */
1003 }
1004 /* success */
1005 r = 0;
1006 out:
1007 sshkey_free(k);
1008 return r;
1009 }
1010
1011 static int
1012 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc)
1013 {
1014 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL;
1015 int r;
1016 size_t elen = 0;
1017
1018 debug3_f("entering");
1019
1020 memset(dc, '\0', sizeof(*dc));
1021 if ((r = sshbuf_froms(m, &b)) != 0 ||
1022 (r = sshbuf_froms(b, &frombuf)) != 0 ||
1023 (r = sshbuf_froms(b, &tobuf)) != 0 ||
1024 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) {
1025 error_fr(r, "parse");
1026 goto out;
1027 }
1028 if ((r = parse_dest_constraint_hop(frombuf, &dc->from) != 0) ||
1029 (r = parse_dest_constraint_hop(tobuf, &dc->to) != 0))
1030 goto out; /* already logged */
1031 if (elen != 0) {
1032 error_f("unsupported extensions (len %zu)", elen);
1033 r = SSH_ERR_FEATURE_UNSUPPORTED;
1034 goto out;
1035 }
1036 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)",
1037 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys,
1038 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "",
1039 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys);
1040 /* check consistency */
1041 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) ||
1042 dc->from.user != NULL) {
1043 error_f("inconsistent \"from\" specification");
1044 r = SSH_ERR_INVALID_FORMAT;
1045 goto out;
1046 }
1047 if (dc->to.hostname == NULL || dc->to.nkeys == 0) {
1048 error_f("incomplete \"to\" specification");
1049 r = SSH_ERR_INVALID_FORMAT;
1050 goto out;
1051 }
1052 /* success */
1053 r = 0;
1054 out:
1055 sshbuf_free(b);
1056 sshbuf_free(frombuf);
1057 sshbuf_free(tobuf);
1058 return r;
1059 }
1060
1061 static int
1062 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp,
1063 struct dest_constraint **dcsp, size_t *ndcsp)
1064 {
1065 char *ext_name = NULL;
1066 int r;
1067 struct sshbuf *b = NULL;
1068
1069 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) {
1070 error_fr(r, "parse constraint extension");
1071 goto out;
1072 }
1073 debug_f("constraint ext %s", ext_name);
1074 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) {
1075 if (sk_providerp == NULL) {
1076 error_f("%s not valid here", ext_name);
1077 r = SSH_ERR_INVALID_FORMAT;
1078 goto out;
1079 }
1080 if (*sk_providerp != NULL) {
1081 error_f("%s already set", ext_name);
1082 r = SSH_ERR_INVALID_FORMAT;
1083 goto out;
1084 }
1085 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) {
1086 error_fr(r, "parse %s", ext_name);
1087 goto out;
1088 }
1089 } else if (strcmp(ext_name,
1090 "restrict-destination-v00@openssh.com") == 0) {
1091 if (*dcsp != NULL) {
1092 error_f("%s already set", ext_name);
1093 goto out;
1094 }
1095 if ((r = sshbuf_froms(m, &b)) != 0) {
1096 error_fr(r, "parse %s outer", ext_name);
1097 goto out;
1098 }
1099 while (sshbuf_len(b) != 0) {
1100 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) {
1101 error_f("too many %s constraints", ext_name);
1102 goto out;
1103 }
1104 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1,
1105 sizeof(**dcsp));
1106 if ((r = parse_dest_constraint(b,
1107 *dcsp + (*ndcsp)++)) != 0)
1108 goto out; /* error already logged */
1109 }
1110 } else {
1111 error_f("unsupported constraint \"%s\"", ext_name);
1112 r = SSH_ERR_FEATURE_UNSUPPORTED;
1113 goto out;
1114 }
1115 /* success */
1116 r = 0;
1117 out:
1118 free(ext_name);
1119 sshbuf_free(b);
1120 return r;
1121 }
1122
1123 static int
1124 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp,
1125 u_int *secondsp, int *confirmp, char **sk_providerp,
1126 struct dest_constraint **dcsp, size_t *ndcsp)
1127 {
1128 u_char ctype;
1129 int r;
1130 u_int seconds, maxsign = 0;
1131
1132 while (sshbuf_len(m)) {
1133 if ((r = sshbuf_get_u8(m, &ctype)) != 0) {
1134 error_fr(r, "parse constraint type");
1135 goto out;
1136 }
1137 switch (ctype) {
1138 case SSH_AGENT_CONSTRAIN_LIFETIME:
1139 if (*deathp != 0) {
1140 error_f("lifetime already set");
1141 r = SSH_ERR_INVALID_FORMAT;
1142 goto out;
1143 }
1144 if ((r = sshbuf_get_u32(m, &seconds)) != 0) {
1145 error_fr(r, "parse lifetime constraint");
1146 goto out;
1147 }
1148 *deathp = monotime() + seconds;
1149 *secondsp = seconds;
1150 break;
1151 case SSH_AGENT_CONSTRAIN_CONFIRM:
1152 if (*confirmp != 0) {
1153 error_f("confirm already set");
1154 r = SSH_ERR_INVALID_FORMAT;
1155 goto out;
1156 }
1157 *confirmp = 1;
1158 break;
1159 case SSH_AGENT_CONSTRAIN_MAXSIGN:
1160 if (k == NULL) {
1161 error_f("maxsign not valid here");
1162 r = SSH_ERR_INVALID_FORMAT;
1163 goto out;
1164 }
1165 if (maxsign != 0) {
1166 error_f("maxsign already set");
1167 r = SSH_ERR_INVALID_FORMAT;
1168 goto out;
1169 }
1170 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) {
1171 error_fr(r, "parse maxsign constraint");
1172 goto out;
1173 }
1174 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) {
1175 error_fr(r, "enable maxsign");
1176 goto out;
1177 }
1178 break;
1179 case SSH_AGENT_CONSTRAIN_EXTENSION:
1180 if ((r = parse_key_constraint_extension(m,
1181 sk_providerp, dcsp, ndcsp)) != 0)
1182 goto out; /* error already logged */
1183 break;
1184 default:
1185 error_f("Unknown constraint %d", ctype);
1186 r = SSH_ERR_FEATURE_UNSUPPORTED;
1187 goto out;
1188 }
1189 }
1190 /* success */
1191 r = 0;
1192 out:
1193 return r;
1194 }
1195
1196 static void
1197 process_add_identity(SocketEntry *e)
1198 {
1199 Identity *id;
1200 int success = 0, confirm = 0;
1201 char *fp, *comment = NULL, *sk_provider = NULL;
1202 char canonical_provider[PATH_MAX];
1203 time_t death = 0;
1204 u_int seconds = 0;
1205 struct dest_constraint *dest_constraints = NULL;
1206 size_t ndest_constraints = 0;
1207 struct sshkey *k = NULL;
1208 int r = SSH_ERR_INTERNAL_ERROR;
1209
1210 debug2_f("entering");
1211 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 ||
1212 k == NULL ||
1213 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) {
1214 error_fr(r, "parse");
1215 goto out;
1216 }
1217 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm,
1218 &sk_provider, &dest_constraints, &ndest_constraints) != 0) {
1219 error_f("failed to parse constraints");
1220 sshbuf_reset(e->request);
1221 goto out;
1222 }
1223
1224 if (sk_provider != NULL) {
1225 if (!sshkey_is_sk(k)) {
1226 error("Cannot add provider: %s is not an "
1227 "authenticator-hosted key", sshkey_type(k));
1228 goto out;
1229 }
1230 if (strcasecmp(sk_provider, "internal") == 0) {
1231 debug_f("internal provider");
1232 } else {
1233 if (realpath(sk_provider, canonical_provider) == NULL) {
1234 verbose("failed provider \"%.100s\": "
1235 "realpath: %s", sk_provider,
1236 strerror(errno));
1237 goto out;
1238 }
1239 free(sk_provider);
1240 sk_provider = xstrdup(canonical_provider);
1241 if (match_pattern_list(sk_provider,
1242 allowed_providers, 0) != 1) {
1243 error("Refusing add key: "
1244 "provider %s not allowed", sk_provider);
1245 goto out;
1246 }
1247 }
1248 }
1249 if ((r = sshkey_shield_private(k)) != 0) {
1250 error_fr(r, "shield private");
1251 goto out;
1252 }
1253 if (lifetime && !death)
1254 death = monotime() + lifetime;
1255 if ((id = lookup_identity(k)) == NULL) {
1256 id = xcalloc(1, sizeof(Identity));
1257 TAILQ_INSERT_TAIL(&idtab->idlist, id, next);
1258 /* Increment the number of identities. */
1259 idtab->nentries++;
1260 } else {
1261 /* identity not visible, do not update */
1262 if (identity_permitted(id, e, NULL, NULL, NULL) != 0)
1263 goto out; /* error already logged */
1264 /* key state might have been updated */
1265 sshkey_free(id->key);
1266 free(id->comment);
1267 free(id->sk_provider);
1268 free_dest_constraints(id->dest_constraints,
1269 id->ndest_constraints);
1270 }
1271 /* success */
1272 id->key = k;
1273 id->comment = comment;
1274 id->death = death;
1275 id->confirm = confirm;
1276 id->sk_provider = sk_provider;
1277 id->dest_constraints = dest_constraints;
1278 id->ndest_constraints = ndest_constraints;
1279
1280 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT,
1281 SSH_FP_DEFAULT)) == NULL)
1282 fatal_f("sshkey_fingerprint failed");
1283 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) "
1284 "(provider: %s) (destination constraints: %zu)",
1285 sshkey_ssh_name(k), fp, comment, seconds, confirm,
1286 sk_provider == NULL ? "none" : sk_provider, ndest_constraints);
1287 free(fp);
1288 /* transferred */
1289 k = NULL;
1290 comment = NULL;
1291 sk_provider = NULL;
1292 dest_constraints = NULL;
1293 ndest_constraints = 0;
1294 success = 1;
1295 out:
1296 free(sk_provider);
1297 free(comment);
1298 sshkey_free(k);
1299 free_dest_constraints(dest_constraints, ndest_constraints);
1300 send_status(e, success);
1301 }
1302
1303 /* XXX todo: encrypt sensitive data with passphrase */
1304 static void
1305 process_lock_agent(SocketEntry *e, int lock)
1306 {
1307 int r, success = 0, delay;
1308 char *passwd;
1309 u_char passwdhash[LOCK_SIZE];
1310 static u_int fail_count = 0;
1311 size_t pwlen;
1312
1313 debug2_f("entering");
1314 /*
1315 * This is deliberately fatal: the user has requested that we lock,
1316 * but we can't parse their request properly. The only safe thing to
1317 * do is abort.
1318 */
1319 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0)
1320 fatal_fr(r, "parse");
1321 if (pwlen == 0) {
1322 debug("empty password not supported");
1323 } else if (locked && !lock) {
1324 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt),
1325 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0)
1326 fatal("bcrypt_pbkdf");
1327 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) {
1328 debug("agent unlocked");
1329 locked = 0;
1330 fail_count = 0;
1331 explicit_bzero(lock_pwhash, sizeof(lock_pwhash));
1332 success = 1;
1333 } else {
1334 /* delay in 0.1s increments up to 10s */
1335 if (fail_count < 100)
1336 fail_count++;
1337 delay = 100000 * fail_count;
1338 debug("unlock failed, delaying %0.1lf seconds",
1339 (double)delay/1000000);
1340 usleep(delay);
1341 }
1342 explicit_bzero(passwdhash, sizeof(passwdhash));
1343 } else if (!locked && lock) {
1344 debug("agent locked");
1345 locked = 1;
1346 arc4random_buf(lock_salt, sizeof(lock_salt));
1347 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt),
1348 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0)
1349 fatal("bcrypt_pbkdf");
1350 success = 1;
1351 }
1352 freezero(passwd, pwlen);
1353 send_status(e, success);
1354 }
1355
1356 static void
1357 no_identities(SocketEntry *e)
1358 {
1359 struct sshbuf *msg;
1360 int r;
1361
1362 if ((msg = sshbuf_new()) == NULL)
1363 fatal_f("sshbuf_new failed");
1364 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
1365 (r = sshbuf_put_u32(msg, 0)) != 0 ||
1366 (r = sshbuf_put_stringb(e->output, msg)) != 0)
1367 fatal_fr(r, "compose");
1368 sshbuf_free(msg);
1369 }
1370
1371 #ifdef ENABLE_PKCS11
1372 static void
1373 process_add_smartcard_key(SocketEntry *e)
1374 {
1375 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX];
1376 char **comments = NULL;
1377 int r, i, count = 0, success = 0, confirm = 0;
1378 u_int seconds = 0;
1379 time_t death = 0;
1380 struct sshkey **keys = NULL, *k;
1381 Identity *id;
1382 struct dest_constraint *dest_constraints = NULL;
1383 size_t ndest_constraints = 0;
1384
1385 debug2_f("entering");
1386 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
1387 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) {
1388 error_fr(r, "parse");
1389 goto send;
1390 }
1391 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm,
1392 NULL, &dest_constraints, &ndest_constraints) != 0) {
1393 error_f("failed to parse constraints");
1394 goto send;
1395 }
1396 if (realpath(provider, canonical_provider) == NULL) {
1397 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s",
1398 provider, strerror(errno));
1399 goto send;
1400 }
1401 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) {
1402 verbose("refusing PKCS#11 add of \"%.100s\": "
1403 "provider not allowed", canonical_provider);
1404 goto send;
1405 }
1406 debug_f("add %.100s", canonical_provider);
1407 if (lifetime && !death)
1408 death = monotime() + lifetime;
1409
1410 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments);
1411 for (i = 0; i < count; i++) {
1412 k = keys[i];
1413 if (lookup_identity(k) == NULL) {
1414 id = xcalloc(1, sizeof(Identity));
1415 id->key = k;
1416 keys[i] = NULL; /* transferred */
1417 id->provider = xstrdup(canonical_provider);
1418 if (*comments[i] != '\0') {
1419 id->comment = comments[i];
1420 comments[i] = NULL; /* transferred */
1421 } else {
1422 id->comment = xstrdup(canonical_provider);
1423 }
1424 id->death = death;
1425 id->confirm = confirm;
1426 id->dest_constraints = dest_constraints;
1427 id->ndest_constraints = ndest_constraints;
1428 dest_constraints = NULL; /* transferred */
1429 ndest_constraints = 0;
1430 TAILQ_INSERT_TAIL(&idtab->idlist, id, next);
1431 idtab->nentries++;
1432 success = 1;
1433 }
1434 /* XXX update constraints for existing keys */
1435 sshkey_free(keys[i]);
1436 free(comments[i]);
1437 }
1438 send:
1439 free(pin);
1440 free(provider);
1441 free(keys);
1442 free(comments);
1443 free_dest_constraints(dest_constraints, ndest_constraints);
1444 send_status(e, success);
1445 }
1446
1447 static void
1448 process_remove_smartcard_key(SocketEntry *e)
1449 {
1450 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX];
1451 int r, success = 0;
1452 Identity *id, *nxt;
1453
1454 debug2_f("entering");
1455 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
1456 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) {
1457 error_fr(r, "parse");
1458 goto send;
1459 }
1460 free(pin);
1461
1462 if (realpath(provider, canonical_provider) == NULL) {
1463 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s",
1464 provider, strerror(errno));
1465 goto send;
1466 }
1467
1468 debug_f("remove %.100s", canonical_provider);
1469 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) {
1470 nxt = TAILQ_NEXT(id, next);
1471 /* Skip file--based keys */
1472 if (id->provider == NULL)
1473 continue;
1474 if (!strcmp(canonical_provider, id->provider)) {
1475 TAILQ_REMOVE(&idtab->idlist, id, next);
1476 free_identity(id);
1477 idtab->nentries--;
1478 }
1479 }
1480 if (pkcs11_del_provider(canonical_provider) == 0)
1481 success = 1;
1482 else
1483 error_f("pkcs11_del_provider failed");
1484 send:
1485 free(provider);
1486 send_status(e, success);
1487 }
1488 #endif /* ENABLE_PKCS11 */
1489
1490 static int
1491 process_ext_session_bind(SocketEntry *e)
1492 {
1493 int r, sid_match, key_match;
1494 struct sshkey *key = NULL;
1495 struct sshbuf *sid = NULL, *sig = NULL;
1496 char *fp = NULL;
1497 size_t i;
1498 u_char fwd = 0;
1499
1500 debug2_f("entering");
1501 if ((r = sshkey_froms(e->request, &key)) != 0 ||
1502 (r = sshbuf_froms(e->request, &sid)) != 0 ||
1503 (r = sshbuf_froms(e->request, &sig)) != 0 ||
1504 (r = sshbuf_get_u8(e->request, &fwd)) != 0) {
1505 error_fr(r, "parse");
1506 goto out;
1507 }
1508 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT,
1509 SSH_FP_DEFAULT)) == NULL)
1510 fatal_f("fingerprint failed");
1511 /* check signature with hostkey on session ID */
1512 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig),
1513 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) {
1514 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp);
1515 goto out;
1516 }
1517 /* check whether sid/key already recorded */
1518 for (i = 0; i < e->nsession_ids; i++) {
1519 if (!e->session_ids[i].forwarded) {
1520 error_f("attempt to bind session ID to socket "
1521 "previously bound for authentication attempt");
1522 r = -1;
1523 goto out;
1524 }
1525 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0;
1526 key_match = sshkey_equal(key, e->session_ids[i].key);
1527 if (sid_match && key_match) {
1528 debug_f("session ID already recorded for %s %s",
1529 sshkey_type(key), fp);
1530 r = 0;
1531 goto out;
1532 } else if (sid_match) {
1533 error_f("session ID recorded against different key "
1534 "for %s %s", sshkey_type(key), fp);
1535 r = -1;
1536 goto out;
1537 }
1538 /*
1539 * new sid with previously-seen key can happen, e.g. multiple
1540 * connections to the same host.
1541 */
1542 }
1543 /* record new key/sid */
1544 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) {
1545 error_f("too many session IDs recorded");
1546 goto out;
1547 }
1548 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids,
1549 e->nsession_ids + 1, sizeof(*e->session_ids));
1550 i = e->nsession_ids++;
1551 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i,
1552 AGENT_MAX_SESSION_IDS);
1553 e->session_ids[i].key = key;
1554 e->session_ids[i].forwarded = fwd != 0;
1555 key = NULL; /* transferred */
1556 /* can't transfer sid; it's refcounted and scoped to request's life */
1557 if ((e->session_ids[i].sid = sshbuf_new()) == NULL)
1558 fatal_f("sshbuf_new");
1559 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0)
1560 fatal_fr(r, "sshbuf_putb session ID");
1561 /* success */
1562 r = 0;
1563 out:
1564 free(fp);
1565 sshkey_free(key);
1566 sshbuf_free(sid);
1567 sshbuf_free(sig);
1568 return r == 0 ? 1 : 0;
1569 }
1570
1571 static void
1572 process_extension(SocketEntry *e)
1573 {
1574 int r, success = 0;
1575 char *name;
1576
1577 debug2_f("entering");
1578 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) {
1579 error_fr(r, "parse");
1580 goto send;
1581 }
1582 if (strcmp(name, "session-bind@openssh.com") == 0)
1583 success = process_ext_session_bind(e);
1584 else
1585 debug_f("unsupported extension \"%s\"", name);
1586 free(name);
1587 send:
1588 send_status(e, success);
1589 }
1590 /*
1591 * dispatch incoming message.
1592 * returns 1 on success, 0 for incomplete messages or -1 on error.
1593 */
1594 static int
1595 process_message(u_int socknum)
1596 {
1597 u_int msg_len;
1598 u_char type;
1599 const u_char *cp;
1600 int r;
1601 SocketEntry *e;
1602
1603 if (socknum >= sockets_alloc)
1604 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc);
1605 e = &sockets[socknum];
1606
1607 if (sshbuf_len(e->input) < 5)
1608 return 0; /* Incomplete message header. */
1609 cp = sshbuf_ptr(e->input);
1610 msg_len = PEEK_U32(cp);
1611 if (msg_len > AGENT_MAX_LEN) {
1612 debug_f("socket %u (fd=%d) message too long %u > %u",
1613 socknum, e->fd, msg_len, AGENT_MAX_LEN);
1614 return -1;
1615 }
1616 if (sshbuf_len(e->input) < msg_len + 4)
1617 return 0; /* Incomplete message body. */
1618
1619 /* move the current input to e->request */
1620 sshbuf_reset(e->request);
1621 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 ||
1622 (r = sshbuf_get_u8(e->request, &type)) != 0) {
1623 if (r == SSH_ERR_MESSAGE_INCOMPLETE ||
1624 r == SSH_ERR_STRING_TOO_LARGE) {
1625 error_fr(r, "parse");
1626 return -1;
1627 }
1628 fatal_fr(r, "parse");
1629 }
1630
1631 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type);
1632
1633 /* check whether agent is locked */
1634 if (locked && type != SSH_AGENTC_UNLOCK) {
1635 sshbuf_reset(e->request);
1636 switch (type) {
1637 case SSH2_AGENTC_REQUEST_IDENTITIES:
1638 /* send empty lists */
1639 no_identities(e);
1640 break;
1641 default:
1642 /* send a fail message for all other request types */
1643 send_status(e, 0);
1644 }
1645 return 1;
1646 }
1647
1648 switch (type) {
1649 case SSH_AGENTC_LOCK:
1650 case SSH_AGENTC_UNLOCK:
1651 process_lock_agent(e, type == SSH_AGENTC_LOCK);
1652 break;
1653 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
1654 process_remove_all_identities(e); /* safe for !WITH_SSH1 */
1655 break;
1656 /* ssh2 */
1657 case SSH2_AGENTC_SIGN_REQUEST:
1658 process_sign_request2(e);
1659 break;
1660 case SSH2_AGENTC_REQUEST_IDENTITIES:
1661 process_request_identities(e);
1662 break;
1663 case SSH2_AGENTC_ADD_IDENTITY:
1664 case SSH2_AGENTC_ADD_ID_CONSTRAINED:
1665 process_add_identity(e);
1666 break;
1667 case SSH2_AGENTC_REMOVE_IDENTITY:
1668 process_remove_identity(e);
1669 break;
1670 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
1671 process_remove_all_identities(e);
1672 break;
1673 #ifdef ENABLE_PKCS11
1674 case SSH_AGENTC_ADD_SMARTCARD_KEY:
1675 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
1676 process_add_smartcard_key(e);
1677 break;
1678 case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
1679 process_remove_smartcard_key(e);
1680 break;
1681 #endif /* ENABLE_PKCS11 */
1682 case SSH_AGENTC_EXTENSION:
1683 process_extension(e);
1684 break;
1685 default:
1686 /* Unknown message. Respond with failure. */
1687 error("Unknown message %d", type);
1688 sshbuf_reset(e->request);
1689 send_status(e, 0);
1690 break;
1691 }
1692 return 1;
1693 }
1694
1695 static void
1696 new_socket(sock_type type, int fd)
1697 {
1698 u_int i, old_alloc, new_alloc;
1699
1700 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" :
1701 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN"));
1702 set_nonblock(fd);
1703
1704 if (fd > max_fd)
1705 max_fd = fd;
1706
1707 for (i = 0; i < sockets_alloc; i++)
1708 if (sockets[i].type == AUTH_UNUSED) {
1709 sockets[i].fd = fd;
1710 if ((sockets[i].input = sshbuf_new()) == NULL ||
1711 (sockets[i].output = sshbuf_new()) == NULL ||
1712 (sockets[i].request = sshbuf_new()) == NULL)
1713 fatal_f("sshbuf_new failed");
1714 sockets[i].type = type;
1715 return;
1716 }
1717 old_alloc = sockets_alloc;
1718 new_alloc = sockets_alloc + 10;
1719 sockets = xrecallocarray(sockets, old_alloc, new_alloc,
1720 sizeof(sockets[0]));
1721 for (i = old_alloc; i < new_alloc; i++)
1722 sockets[i].type = AUTH_UNUSED;
1723 sockets_alloc = new_alloc;
1724 sockets[old_alloc].fd = fd;
1725 if ((sockets[old_alloc].input = sshbuf_new()) == NULL ||
1726 (sockets[old_alloc].output = sshbuf_new()) == NULL ||
1727 (sockets[old_alloc].request = sshbuf_new()) == NULL)
1728 fatal_f("sshbuf_new failed");
1729 sockets[old_alloc].type = type;
1730 }
1731
1732 static int
1733 handle_socket_read(u_int socknum)
1734 {
1735 struct sockaddr_un sunaddr;
1736 socklen_t slen;
1737 uid_t euid;
1738 gid_t egid;
1739 int fd;
1740
1741 slen = sizeof(sunaddr);
1742 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen);
1743 if (fd == -1) {
1744 error("accept from AUTH_SOCKET: %s", strerror(errno));
1745 return -1;
1746 }
1747 if (getpeereid(fd, &euid, &egid) == -1) {
1748 error("getpeereid %d failed: %s", fd, strerror(errno));
1749 close(fd);
1750 return -1;
1751 }
1752 if ((euid != 0) && (getuid() != euid)) {
1753 error("uid mismatch: peer euid %u != uid %u",
1754 (u_int) euid, (u_int) getuid());
1755 close(fd);
1756 return -1;
1757 }
1758 new_socket(AUTH_CONNECTION, fd);
1759 return 0;
1760 }
1761
1762 static int
1763 handle_conn_read(u_int socknum)
1764 {
1765 char buf[AGENT_RBUF_LEN];
1766 ssize_t len;
1767 int r;
1768
1769 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) {
1770 if (len == -1) {
1771 if (errno == EAGAIN || errno == EINTR)
1772 return 0;
1773 error_f("read error on socket %u (fd %d): %s",
1774 socknum, sockets[socknum].fd, strerror(errno));
1775 }
1776 return -1;
1777 }
1778 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0)
1779 fatal_fr(r, "compose");
1780 explicit_bzero(buf, sizeof(buf));
1781 for (;;) {
1782 if ((r = process_message(socknum)) == -1)
1783 return -1;
1784 else if (r == 0)
1785 break;
1786 }
1787 return 0;
1788 }
1789
1790 static int
1791 handle_conn_write(u_int socknum)
1792 {
1793 ssize_t len;
1794 int r;
1795
1796 if (sshbuf_len(sockets[socknum].output) == 0)
1797 return 0; /* shouldn't happen */
1798 if ((len = write(sockets[socknum].fd,
1799 sshbuf_ptr(sockets[socknum].output),
1800 sshbuf_len(sockets[socknum].output))) <= 0) {
1801 if (len == -1) {
1802 if (errno == EAGAIN || errno == EINTR)
1803 return 0;
1804 error_f("read error on socket %u (fd %d): %s",
1805 socknum, sockets[socknum].fd, strerror(errno));
1806 }
1807 return -1;
1808 }
1809 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0)
1810 fatal_fr(r, "consume");
1811 return 0;
1812 }
1813
1814 static void
1815 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds)
1816 {
1817 size_t i;
1818 u_int socknum, activefds = npfd;
1819
1820 for (i = 0; i < npfd; i++) {
1821 if (pfd[i].revents == 0)
1822 continue;
1823 /* Find sockets entry */
1824 for (socknum = 0; socknum < sockets_alloc; socknum++) {
1825 if (sockets[socknum].type != AUTH_SOCKET &&
1826 sockets[socknum].type != AUTH_CONNECTION)
1827 continue;
1828 if (pfd[i].fd == sockets[socknum].fd)
1829 break;
1830 }
1831 if (socknum >= sockets_alloc) {
1832 error_f("no socket for fd %d", pfd[i].fd);
1833 continue;
1834 }
1835 /* Process events */
1836 switch (sockets[socknum].type) {
1837 case AUTH_SOCKET:
1838 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0)
1839 break;
1840 if (npfd > maxfds) {
1841 debug3("out of fds (active %u >= limit %u); "
1842 "skipping accept", activefds, maxfds);
1843 break;
1844 }
1845 if (handle_socket_read(socknum) == 0)
1846 activefds++;
1847 break;
1848 case AUTH_CONNECTION:
1849 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 &&
1850 handle_conn_read(socknum) != 0)
1851 goto close_sock;
1852 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 &&
1853 handle_conn_write(socknum) != 0) {
1854 close_sock:
1855 if (activefds == 0)
1856 fatal("activefds == 0 at close_sock");
1857 close_socket(&sockets[socknum]);
1858 activefds--;
1859 break;
1860 }
1861 break;
1862 default:
1863 break;
1864 }
1865 }
1866 }
1867
1868 static int
1869 prepare_poll(struct pollfd **pfdp, size_t *npfdp, int *timeoutp, u_int maxfds)
1870 {
1871 struct pollfd *pfd = *pfdp;
1872 size_t i, j, npfd = 0;
1873 time_t deadline;
1874 int r;
1875
1876 /* Count active sockets */
1877 for (i = 0; i < sockets_alloc; i++) {
1878 switch (sockets[i].type) {
1879 case AUTH_SOCKET:
1880 case AUTH_CONNECTION:
1881 npfd++;
1882 break;
1883 case AUTH_UNUSED:
1884 break;
1885 default:
1886 fatal("Unknown socket type %d", sockets[i].type);
1887 break;
1888 }
1889 }
1890 if (npfd != *npfdp &&
1891 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL)
1892 fatal_f("recallocarray failed");
1893 *pfdp = pfd;
1894 *npfdp = npfd;
1895
1896 for (i = j = 0; i < sockets_alloc; i++) {
1897 switch (sockets[i].type) {
1898 case AUTH_SOCKET:
1899 if (npfd > maxfds) {
1900 debug3("out of fds (active %zu >= limit %u); "
1901 "skipping arming listener", npfd, maxfds);
1902 break;
1903 }
1904 pfd[j].fd = sockets[i].fd;
1905 pfd[j].revents = 0;
1906 pfd[j].events = POLLIN;
1907 j++;
1908 break;
1909 case AUTH_CONNECTION:
1910 pfd[j].fd = sockets[i].fd;
1911 pfd[j].revents = 0;
1912 /*
1913 * Only prepare to read if we can handle a full-size
1914 * input read buffer and enqueue a max size reply..
1915 */
1916 if ((r = sshbuf_check_reserve(sockets[i].input,
1917 AGENT_RBUF_LEN)) == 0 &&
1918 (r = sshbuf_check_reserve(sockets[i].output,
1919 AGENT_MAX_LEN)) == 0)
1920 pfd[j].events = POLLIN;
1921 else if (r != SSH_ERR_NO_BUFFER_SPACE)
1922 fatal_fr(r, "reserve");
1923 if (sshbuf_len(sockets[i].output) > 0)
1924 pfd[j].events |= POLLOUT;
1925 j++;
1926 break;
1927 default:
1928 break;
1929 }
1930 }
1931 deadline = reaper();
1932 if (parent_alive_interval != 0)
1933 deadline = (deadline == 0) ? parent_alive_interval :
1934 MINIMUM(deadline, parent_alive_interval);
1935 if (deadline == 0) {
1936 *timeoutp = -1; /* INFTIM */
1937 } else {
1938 if (deadline > INT_MAX / 1000)
1939 *timeoutp = INT_MAX / 1000;
1940 else
1941 *timeoutp = deadline * 1000;
1942 }
1943 return (1);
1944 }
1945
1946 static void
1947 cleanup_socket(void)
1948 {
1949 if (cleanup_pid != 0 && getpid() != cleanup_pid)
1950 return;
1951 debug_f("cleanup");
1952 if (socket_name[0])
1953 unlink(socket_name);
1954 if (socket_dir[0])
1955 rmdir(socket_dir);
1956 }
1957
1958 void
1959 cleanup_exit(int i)
1960 {
1961 cleanup_socket();
1962 _exit(i);
1963 }
1964
1965 /*ARGSUSED*/
1966 static void
1967 cleanup_handler(int sig)
1968 {
1969 cleanup_socket();
1970 #ifdef ENABLE_PKCS11
1971 pkcs11_terminate();
1972 #endif
1973 _exit(2);
1974 }
1975
1976 static void
1977 check_parent_exists(void)
1978 {
1979 /*
1980 * If our parent has exited then getppid() will return (pid_t)1,
1981 * so testing for that should be safe.
1982 */
1983 if (parent_pid != -1 && getppid() != parent_pid) {
1984 /* printf("Parent has died - Authentication agent exiting.\n"); */
1985 cleanup_socket();
1986 _exit(2);
1987 }
1988 }
1989
1990 static void
1991 usage(void)
1992 {
1993 fprintf(stderr,
1994 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n"
1995 " [-P allowed_providers] [-t life]\n"
1996 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-P allowed_providers]\n"
1997 " [-t life] command [arg ...]\n"
1998 " ssh-agent [-c | -s] -k\n");
1999 exit(1);
2000 }
2001
2002 int
2003 main(int ac, char **av)
2004 {
2005 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0;
2006 int sock, ch, result, saved_errno;
2007 char *shell, *format, *pidstr, *agentsocket = NULL;
2008 #ifdef HAVE_SETRLIMIT
2009 struct rlimit rlim;
2010 #endif
2011 extern int optind;
2012 extern char *optarg;
2013 pid_t pid;
2014 char pidstrbuf[1 + 3 * sizeof pid];
2015 size_t len;
2016 mode_t prev_mask;
2017 int timeout = -1; /* INFTIM */
2018 struct pollfd *pfd = NULL;
2019 size_t npfd = 0;
2020 u_int maxfds;
2021
2022 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
2023 sanitise_stdfd();
2024
2025 /* drop */
2026 setegid(getgid());
2027 setgid(getgid());
2028
2029 platform_disable_tracing(0); /* strict=no */
2030
2031 #ifdef RLIMIT_NOFILE
2032 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1)
2033 fatal("%s: getrlimit: %s", __progname, strerror(errno));
2034 #endif
2035
2036 __progname = ssh_get_progname(av[0]);
2037 seed_rng();
2038
2039 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:")) != -1) {
2040 switch (ch) {
2041 case 'E':
2042 fingerprint_hash = ssh_digest_alg_by_name(optarg);
2043 if (fingerprint_hash == -1)
2044 fatal("Invalid hash algorithm \"%s\"", optarg);
2045 break;
2046 case 'c':
2047 if (s_flag)
2048 usage();
2049 c_flag++;
2050 break;
2051 case 'k':
2052 k_flag++;
2053 break;
2054 case 'O':
2055 if (strcmp(optarg, "no-restrict-websafe") == 0)
2056 restrict_websafe = 0;
2057 else
2058 fatal("Unknown -O option");
2059 break;
2060 case 'P':
2061 if (allowed_providers != NULL)
2062 fatal("-P option already specified");
2063 allowed_providers = xstrdup(optarg);
2064 break;
2065 case 's':
2066 if (c_flag)
2067 usage();
2068 s_flag++;
2069 break;
2070 case 'd':
2071 if (d_flag || D_flag)
2072 usage();
2073 d_flag++;
2074 break;
2075 case 'D':
2076 if (d_flag || D_flag)
2077 usage();
2078 D_flag++;
2079 break;
2080 case 'a':
2081 agentsocket = optarg;
2082 break;
2083 case 't':
2084 if ((lifetime = convtime(optarg)) == -1) {
2085 fprintf(stderr, "Invalid lifetime\n");
2086 usage();
2087 }
2088 break;
2089 default:
2090 usage();
2091 }
2092 }
2093 ac -= optind;
2094 av += optind;
2095
2096 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag))
2097 usage();
2098
2099 if (allowed_providers == NULL)
2100 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS);
2101
2102 if (ac == 0 && !c_flag && !s_flag) {
2103 shell = getenv("SHELL");
2104 if (shell != NULL && (len = strlen(shell)) > 2 &&
2105 strncmp(shell + len - 3, "csh", 3) == 0)
2106 c_flag = 1;
2107 }
2108 if (k_flag) {
2109 const char *errstr = NULL;
2110
2111 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
2112 if (pidstr == NULL) {
2113 fprintf(stderr, "%s not set, cannot kill agent\n",
2114 SSH_AGENTPID_ENV_NAME);
2115 exit(1);
2116 }
2117 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
2118 if (errstr) {
2119 fprintf(stderr,
2120 "%s=\"%s\", which is not a good PID: %s\n",
2121 SSH_AGENTPID_ENV_NAME, pidstr, errstr);
2122 exit(1);
2123 }
2124 if (kill(pid, SIGTERM) == -1) {
2125 perror("kill");
2126 exit(1);
2127 }
2128 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
2129 printf(format, SSH_AUTHSOCKET_ENV_NAME);
2130 printf(format, SSH_AGENTPID_ENV_NAME);
2131 printf("echo Agent pid %ld killed;\n", (long)pid);
2132 exit(0);
2133 }
2134
2135 /*
2136 * Minimum file descriptors:
2137 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) +
2138 * a few spare for libc / stack protectors / sanitisers, etc.
2139 */
2140 #define SSH_AGENT_MIN_FDS (3+1+1+1+4)
2141 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS)
2142 fatal("%s: file descriptor rlimit %lld too low (minimum %u)",
2143 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS);
2144 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS;
2145
2146 parent_pid = getpid();
2147
2148 if (agentsocket == NULL) {
2149 /* Create private directory for agent socket */
2150 mktemp_proto(socket_dir, sizeof(socket_dir));
2151 if (mkdtemp(socket_dir) == NULL) {
2152 perror("mkdtemp: private socket dir");
2153 exit(1);
2154 }
2155 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
2156 (long)parent_pid);
2157 } else {
2158 /* Try to use specified agent socket */
2159 socket_dir[0] = '\0';
2160 strlcpy(socket_name, agentsocket, sizeof socket_name);
2161 }
2162
2163 /*
2164 * Create socket early so it will exist before command gets run from
2165 * the parent.
2166 */
2167 prev_mask = umask(0177);
2168 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0);
2169 if (sock < 0) {
2170 /* XXX - unix_listener() calls error() not perror() */
2171 *socket_name = '\0'; /* Don't unlink any existing file */
2172 cleanup_exit(1);
2173 }
2174 umask(prev_mask);
2175
2176 /*
2177 * Fork, and have the parent execute the command, if any, or present
2178 * the socket data. The child continues as the authentication agent.
2179 */
2180 if (D_flag || d_flag) {
2181 log_init(__progname,
2182 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO,
2183 SYSLOG_FACILITY_AUTH, 1);
2184 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
2185 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
2186 SSH_AUTHSOCKET_ENV_NAME);
2187 printf("echo Agent pid %ld;\n", (long)parent_pid);
2188 fflush(stdout);
2189 goto skip;
2190 }
2191 pid = fork();
2192 if (pid == -1) {
2193 perror("fork");
2194 cleanup_exit(1);
2195 }
2196 if (pid != 0) { /* Parent - execute the given command. */
2197 close(sock);
2198 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
2199 if (ac == 0) {
2200 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
2201 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
2202 SSH_AUTHSOCKET_ENV_NAME);
2203 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
2204 SSH_AGENTPID_ENV_NAME);
2205 printf("echo Agent pid %ld;\n", (long)pid);
2206 exit(0);
2207 }
2208 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
2209 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
2210 perror("setenv");
2211 exit(1);
2212 }
2213 execvp(av[0], av);
2214 perror(av[0]);
2215 exit(1);
2216 }
2217 /* child */
2218 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
2219
2220 if (setsid() == -1) {
2221 error("setsid: %s", strerror(errno));
2222 cleanup_exit(1);
2223 }
2224
2225 (void)chdir("/");
2226 if (stdfd_devnull(1, 1, 1) == -1)
2227 error_f("stdfd_devnull failed");
2228
2229 #ifdef HAVE_SETRLIMIT
2230 /* deny core dumps, since memory contains unencrypted private keys */
2231 rlim.rlim_cur = rlim.rlim_max = 0;
2232 if (setrlimit(RLIMIT_CORE, &rlim) == -1) {
2233 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
2234 cleanup_exit(1);
2235 }
2236 #endif
2237
2238 skip:
2239
2240 cleanup_pid = getpid();
2241
2242 #ifdef ENABLE_PKCS11
2243 pkcs11_init(0);
2244 #endif
2245 new_socket(AUTH_SOCKET, sock);
2246 if (ac > 0)
2247 parent_alive_interval = 10;
2248 idtab_init();
2249 ssh_signal(SIGPIPE, SIG_IGN);
2250 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN);
2251 ssh_signal(SIGHUP, cleanup_handler);
2252 ssh_signal(SIGTERM, cleanup_handler);
2253
2254 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1)
2255 fatal("%s: pledge: %s", __progname, strerror(errno));
2256 platform_pledge_agent();
2257
2258 while (1) {
2259 prepare_poll(&pfd, &npfd, &timeout, maxfds);
2260 result = poll(pfd, npfd, timeout);
2261 saved_errno = errno;
2262 if (parent_alive_interval != 0)
2263 check_parent_exists();
2264 (void) reaper(); /* remove expired keys */
2265 if (result == -1) {
2266 if (saved_errno == EINTR)
2267 continue;
2268 fatal("poll: %s", strerror(saved_errno));
2269 } else if (result > 0)
2270 after_poll(pfd, npfd, maxfds);
2271 }
2272 /* NOTREACHED */
2273 }
DragonFly BSD