1 /* $OpenBSD: ssh-agent.c,v 1.310 2025/02/18 08:02:48 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 "log.h"
84 #include "misc.h"
85 #include "digest.h"
86 #include "ssherr.h"
87 #include "match.h"
88 #include "msg.h"
89 #include "pathnames.h"
90 #include "ssh-pkcs11.h"
91 #include "sk-api.h"
92 #include "myproposal.h"
93
94 #ifndef DEFAULT_ALLOWED_PROVIDERS
95 # define DEFAULT_ALLOWED_PROVIDERS "/usr/lib*/*,/usr/local/lib*/*"
96 #endif
97 #ifndef DEFAULT_WEBSAFE_ALLOWLIST
98 # define DEFAULT_WEBSAFE_ALLOWLIST "ssh:*"
99 #endif
100
101 /* Maximum accepted message length */
102 #define AGENT_MAX_LEN (256*1024)
103 /* Maximum bytes to read from client socket */
104 #define AGENT_RBUF_LEN (4096)
105 /* Maximum number of recorded session IDs/hostkeys per connection */
106 #define AGENT_MAX_SESSION_IDS 16
107 /* Maximum size of session ID */
108 #define AGENT_MAX_SID_LEN 128
109 /* Maximum number of destination constraints to accept on a key */
110 #define AGENT_MAX_DEST_CONSTRAINTS 1024
111 /* Maximum number of associated certificate constraints to accept on a key */
112 #define AGENT_MAX_EXT_CERTS 1024
113
114 /* XXX store hostkey_sid in a refcounted tree */
115
116 typedef enum {
117 AUTH_UNUSED = 0,
118 AUTH_SOCKET = 1,
119 AUTH_CONNECTION = 2,
120 } sock_type;
121
122 struct hostkey_sid {
123 struct sshkey *key;
124 struct sshbuf *sid;
125 int forwarded;
126 };
127
128 typedef struct socket_entry {
129 int fd;
130 sock_type type;
131 struct sshbuf *input;
132 struct sshbuf *output;
133 struct sshbuf *request;
134 size_t nsession_ids;
135 struct hostkey_sid *session_ids;
136 int session_bind_attempted;
137 } SocketEntry;
138
139 u_int sockets_alloc = 0;
140 SocketEntry *sockets = NULL;
141
142 typedef struct identity {
143 TAILQ_ENTRY(identity) next;
144 struct sshkey *key;
145 char *comment;
146 char *provider;
147 time_t death;
148 u_int confirm;
149 char *sk_provider;
150 struct dest_constraint *dest_constraints;
151 size_t ndest_constraints;
152 } Identity;
153
154 struct idtable {
155 int nentries;
156 TAILQ_HEAD(idqueue, identity) idlist;
157 };
158
159 /* private key table */
160 struct idtable *idtab;
161
162 int max_fd = 0;
163
164 /* pid of shell == parent of agent */
165 pid_t parent_pid = -1;
166 time_t parent_alive_interval = 0;
167
168 static sig_atomic_t signalled_exit;
169 static sig_atomic_t signalled_keydrop;
170
171 /* pid of process for which cleanup_socket is applicable */
172 pid_t cleanup_pid = 0;
173
174 /* pathname and directory for AUTH_SOCKET */
175 char socket_name[PATH_MAX];
176 char socket_dir[PATH_MAX];
177
178 /* Pattern-list of allowed PKCS#11/Security key paths */
179 static char *allowed_providers;
180
181 /*
182 * Allows PKCS11 providers or SK keys that use non-internal providers to
183 * be added over a remote connection (identified by session-bind@openssh.com).
184 */
185 static int remote_add_provider;
186
187 /* locking */
188 #define LOCK_SIZE 32
189 #define LOCK_SALT_SIZE 16
190 #define LOCK_ROUNDS 1
191 int locked = 0;
192 u_char lock_pwhash[LOCK_SIZE];
193 u_char lock_salt[LOCK_SALT_SIZE];
194
195 extern char *__progname;
196
197 /* Default lifetime in seconds (0 == forever) */
198 static int lifetime = 0;
199
200 static int fingerprint_hash = SSH_FP_HASH_DEFAULT;
201
202 /* Refuse signing of non-SSH messages for web-origin FIDO keys */
203 static int restrict_websafe = 1;
204 static char *websafe_allowlist;
205
206 /*
207 * Client connection count; incremented in new_socket() and decremented in
208 * close_socket(). When it reaches 0, ssh-agent will exit. Since it is
209 * normally initialized to 1, it will never reach 0. However, if the -x
210 * option is specified, it is initialized to 0 in main(); in that case,
211 * ssh-agent will exit as soon as it has had at least one client but no
212 * longer has any.
213 */
214 static int xcount = 1;
215
216 static void
close_socket(SocketEntry * e)217 close_socket(SocketEntry *e)
218 {
219 size_t i;
220 int last = 0;
221
222 if (e->type == AUTH_CONNECTION) {
223 debug("xcount %d -> %d", xcount, xcount - 1);
224 if (--xcount == 0)
225 last = 1;
226 }
227 close(e->fd);
228 sshbuf_free(e->input);
229 sshbuf_free(e->output);
230 sshbuf_free(e->request);
231 for (i = 0; i < e->nsession_ids; i++) {
232 sshkey_free(e->session_ids[i].key);
233 sshbuf_free(e->session_ids[i].sid);
234 }
235 free(e->session_ids);
236 memset(e, '\0', sizeof(*e));
237 e->fd = -1;
238 e->type = AUTH_UNUSED;
239 if (last)
240 cleanup_exit(0);
241 }
242
243 static void
idtab_init(void)244 idtab_init(void)
245 {
246 idtab = xcalloc(1, sizeof(*idtab));
247 TAILQ_INIT(&idtab->idlist);
248 idtab->nentries = 0;
249 }
250
251 static void
free_dest_constraint_hop(struct dest_constraint_hop * dch)252 free_dest_constraint_hop(struct dest_constraint_hop *dch)
253 {
254 u_int i;
255
256 if (dch == NULL)
257 return;
258 free(dch->user);
259 free(dch->hostname);
260 for (i = 0; i < dch->nkeys; i++)
261 sshkey_free(dch->keys[i]);
262 free(dch->keys);
263 free(dch->key_is_ca);
264 }
265
266 static void
free_dest_constraints(struct dest_constraint * dcs,size_t ndcs)267 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs)
268 {
269 size_t i;
270
271 for (i = 0; i < ndcs; i++) {
272 free_dest_constraint_hop(&dcs[i].from);
273 free_dest_constraint_hop(&dcs[i].to);
274 }
275 free(dcs);
276 }
277
278 #ifdef ENABLE_PKCS11
279 static void
dup_dest_constraint_hop(const struct dest_constraint_hop * dch,struct dest_constraint_hop * out)280 dup_dest_constraint_hop(const struct dest_constraint_hop *dch,
281 struct dest_constraint_hop *out)
282 {
283 u_int i;
284 int r;
285
286 out->user = dch->user == NULL ? NULL : xstrdup(dch->user);
287 out->hostname = dch->hostname == NULL ? NULL : xstrdup(dch->hostname);
288 out->is_ca = dch->is_ca;
289 out->nkeys = dch->nkeys;
290 out->keys = out->nkeys == 0 ? NULL :
291 xcalloc(out->nkeys, sizeof(*out->keys));
292 out->key_is_ca = out->nkeys == 0 ? NULL :
293 xcalloc(out->nkeys, sizeof(*out->key_is_ca));
294 for (i = 0; i < dch->nkeys; i++) {
295 if (dch->keys[i] != NULL &&
296 (r = sshkey_from_private(dch->keys[i],
297 &(out->keys[i]))) != 0)
298 fatal_fr(r, "copy key");
299 out->key_is_ca[i] = dch->key_is_ca[i];
300 }
301 }
302
303 static struct dest_constraint *
dup_dest_constraints(const struct dest_constraint * dcs,size_t ndcs)304 dup_dest_constraints(const struct dest_constraint *dcs, size_t ndcs)
305 {
306 size_t i;
307 struct dest_constraint *ret;
308
309 if (ndcs == 0)
310 return NULL;
311 ret = xcalloc(ndcs, sizeof(*ret));
312 for (i = 0; i < ndcs; i++) {
313 dup_dest_constraint_hop(&dcs[i].from, &ret[i].from);
314 dup_dest_constraint_hop(&dcs[i].to, &ret[i].to);
315 }
316 return ret;
317 }
318 #endif /* ENABLE_PKCS11 */
319
320 #ifdef DEBUG_CONSTRAINTS
321 static void
dump_dest_constraint_hop(const struct dest_constraint_hop * dch)322 dump_dest_constraint_hop(const struct dest_constraint_hop *dch)
323 {
324 u_int i;
325 char *fp;
326
327 debug_f("user %s hostname %s is_ca %d nkeys %u",
328 dch->user == NULL ? "(null)" : dch->user,
329 dch->hostname == NULL ? "(null)" : dch->hostname,
330 dch->is_ca, dch->nkeys);
331 for (i = 0; i < dch->nkeys; i++) {
332 fp = NULL;
333 if (dch->keys[i] != NULL &&
334 (fp = sshkey_fingerprint(dch->keys[i],
335 SSH_FP_HASH_DEFAULT, SSH_FP_DEFAULT)) == NULL)
336 fatal_f("fingerprint failed");
337 debug_f("key %u/%u: %s%s%s key_is_ca %d", i, dch->nkeys,
338 dch->keys[i] == NULL ? "" : sshkey_ssh_name(dch->keys[i]),
339 dch->keys[i] == NULL ? "" : " ",
340 dch->keys[i] == NULL ? "none" : fp,
341 dch->key_is_ca[i]);
342 free(fp);
343 }
344 }
345 #endif /* DEBUG_CONSTRAINTS */
346
347 static void
dump_dest_constraints(const char * context,const struct dest_constraint * dcs,size_t ndcs)348 dump_dest_constraints(const char *context,
349 const struct dest_constraint *dcs, size_t ndcs)
350 {
351 #ifdef DEBUG_CONSTRAINTS
352 size_t i;
353
354 debug_f("%s: %zu constraints", context, ndcs);
355 for (i = 0; i < ndcs; i++) {
356 debug_f("constraint %zu / %zu: from: ", i, ndcs);
357 dump_dest_constraint_hop(&dcs[i].from);
358 debug_f("constraint %zu / %zu: to: ", i, ndcs);
359 dump_dest_constraint_hop(&dcs[i].to);
360 }
361 debug_f("done for %s", context);
362 #endif /* DEBUG_CONSTRAINTS */
363 }
364
365 static void
free_identity(Identity * id)366 free_identity(Identity *id)
367 {
368 sshkey_free(id->key);
369 free(id->provider);
370 free(id->comment);
371 free(id->sk_provider);
372 free_dest_constraints(id->dest_constraints, id->ndest_constraints);
373 free(id);
374 }
375
376 /*
377 * Match 'key' against the key/CA list in a destination constraint hop
378 * Returns 0 on success or -1 otherwise.
379 */
380 static int
match_key_hop(const char * tag,const struct sshkey * key,const struct dest_constraint_hop * dch)381 match_key_hop(const char *tag, const struct sshkey *key,
382 const struct dest_constraint_hop *dch)
383 {
384 const char *reason = NULL;
385 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)";
386 u_int i;
387 char *fp;
388
389 if (key == NULL)
390 return -1;
391 /* XXX logspam */
392 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT,
393 SSH_FP_DEFAULT)) == NULL)
394 fatal_f("fingerprint failed");
395 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail",
396 tag, hostname, sshkey_type(key), fp, dch->nkeys);
397 free(fp);
398 for (i = 0; i < dch->nkeys; i++) {
399 if (dch->keys[i] == NULL)
400 return -1;
401 /* XXX logspam */
402 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT,
403 SSH_FP_DEFAULT)) == NULL)
404 fatal_f("fingerprint failed");
405 debug3_f("%s: key %u: %s%s %s", tag, i,
406 dch->key_is_ca[i] ? "CA " : "",
407 sshkey_type(dch->keys[i]), fp);
408 free(fp);
409 if (!sshkey_is_cert(key)) {
410 /* plain key */
411 if (dch->key_is_ca[i] ||
412 !sshkey_equal(key, dch->keys[i]))
413 continue;
414 return 0;
415 }
416 /* certificate */
417 if (!dch->key_is_ca[i])
418 continue;
419 if (key->cert == NULL || key->cert->signature_key == NULL)
420 return -1; /* shouldn't happen */
421 if (!sshkey_equal(key->cert->signature_key, dch->keys[i]))
422 continue;
423 if (sshkey_cert_check_host(key, hostname, 1,
424 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) {
425 debug_f("cert %s / hostname %s rejected: %s",
426 key->cert->key_id, hostname, reason);
427 continue;
428 }
429 return 0;
430 }
431 return -1;
432 }
433
434 /* Check destination constraints on an identity against the hostkey/user */
435 static int
permitted_by_dest_constraints(const struct sshkey * fromkey,const struct sshkey * tokey,Identity * id,const char * user,const char ** hostnamep)436 permitted_by_dest_constraints(const struct sshkey *fromkey,
437 const struct sshkey *tokey, Identity *id, const char *user,
438 const char **hostnamep)
439 {
440 size_t i;
441 struct dest_constraint *d;
442
443 if (hostnamep != NULL)
444 *hostnamep = NULL;
445 for (i = 0; i < id->ndest_constraints; i++) {
446 d = id->dest_constraints + i;
447 /* XXX remove logspam */
448 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)",
449 i, d->from.user ? d->from.user : "",
450 d->from.user ? "@" : "",
451 d->from.hostname ? d->from.hostname : "(ORIGIN)",
452 d->from.nkeys,
453 d->to.user ? d->to.user : "", d->to.user ? "@" : "",
454 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys);
455
456 /* Match 'from' key */
457 if (fromkey == NULL) {
458 /* We are matching the first hop */
459 if (d->from.hostname != NULL || d->from.nkeys != 0)
460 continue;
461 } else if (match_key_hop("from", fromkey, &d->from) != 0)
462 continue;
463
464 /* Match 'to' key */
465 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0)
466 continue;
467
468 /* Match user if specified */
469 if (d->to.user != NULL && user != NULL &&
470 !match_pattern(user, d->to.user))
471 continue;
472
473 /* successfully matched this constraint */
474 if (hostnamep != NULL)
475 *hostnamep = d->to.hostname;
476 debug2_f("allowed for hostname %s",
477 d->to.hostname == NULL ? "*" : d->to.hostname);
478 return 0;
479 }
480 /* no match */
481 debug2_f("%s identity \"%s\" not permitted for this destination",
482 sshkey_type(id->key), id->comment);
483 return -1;
484 }
485
486 /*
487 * Check whether hostkeys on a SocketEntry and the optionally specified user
488 * are permitted by the destination constraints on the Identity.
489 * Returns 0 on success or -1 otherwise.
490 */
491 static int
identity_permitted(Identity * id,SocketEntry * e,char * user,const char ** forward_hostnamep,const char ** last_hostnamep)492 identity_permitted(Identity *id, SocketEntry *e, char *user,
493 const char **forward_hostnamep, const char **last_hostnamep)
494 {
495 size_t i;
496 const char **hp;
497 struct hostkey_sid *hks;
498 const struct sshkey *fromkey = NULL;
499 const char *test_user;
500 char *fp1, *fp2;
501
502 /* XXX remove logspam */
503 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, "
504 "%zu constraints", sshkey_type(id->key), id->comment,
505 e->nsession_ids, id->ndest_constraints);
506 if (id->ndest_constraints == 0)
507 return 0; /* unconstrained */
508 if (e->session_bind_attempted && e->nsession_ids == 0) {
509 error_f("previous session bind failed on socket");
510 return -1;
511 }
512 if (e->nsession_ids == 0)
513 return 0; /* local use */
514 /*
515 * Walk through the hops recorded by session_id and try to find a
516 * constraint that satisfies each.
517 */
518 for (i = 0; i < e->nsession_ids; i++) {
519 hks = e->session_ids + i;
520 if (hks->key == NULL)
521 fatal_f("internal error: no bound key");
522 /* XXX remove logspam */
523 fp1 = fp2 = NULL;
524 if (fromkey != NULL &&
525 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT,
526 SSH_FP_DEFAULT)) == NULL)
527 fatal_f("fingerprint failed");
528 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT,
529 SSH_FP_DEFAULT)) == NULL)
530 fatal_f("fingerprint failed");
531 debug3_f("socketentry fd=%d, entry %zu %s, "
532 "from hostkey %s %s to user %s hostkey %s %s",
533 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH",
534 fromkey ? sshkey_type(fromkey) : "(ORIGIN)",
535 fromkey ? fp1 : "", user ? user : "(ANY)",
536 sshkey_type(hks->key), fp2);
537 free(fp1);
538 free(fp2);
539 /*
540 * Record the hostnames for the initial forwarding and
541 * the final destination.
542 */
543 hp = NULL;
544 if (i == e->nsession_ids - 1)
545 hp = last_hostnamep;
546 else if (i == 0)
547 hp = forward_hostnamep;
548 /* Special handling for final recorded binding */
549 test_user = NULL;
550 if (i == e->nsession_ids - 1) {
551 /* Can only check user at final hop */
552 test_user = user;
553 /*
554 * user is only presented for signature requests.
555 * If this is the case, make sure last binding is not
556 * for a forwarding.
557 */
558 if (hks->forwarded && user != NULL) {
559 error_f("tried to sign on forwarding hop");
560 return -1;
561 }
562 } else if (!hks->forwarded) {
563 error_f("tried to forward though signing bind");
564 return -1;
565 }
566 if (permitted_by_dest_constraints(fromkey, hks->key, id,
567 test_user, hp) != 0)
568 return -1;
569 fromkey = hks->key;
570 }
571 /*
572 * Another special case: if the last bound session ID was for a
573 * forwarding, and this function is not being called to check a sign
574 * request (i.e. no 'user' supplied), then only permit the key if
575 * there is a permission that would allow it to be used at another
576 * destination. This hides keys that are allowed to be used to
577 * authenticate *to* a host but not permitted for *use* beyond it.
578 */
579 hks = &e->session_ids[e->nsession_ids - 1];
580 if (hks->forwarded && user == NULL &&
581 permitted_by_dest_constraints(hks->key, NULL, id,
582 NULL, NULL) != 0) {
583 debug3_f("key permitted at host but not after");
584 return -1;
585 }
586
587 /* success */
588 return 0;
589 }
590
591 static int
socket_is_remote(SocketEntry * e)592 socket_is_remote(SocketEntry *e)
593 {
594 return e->session_bind_attempted || (e->nsession_ids != 0);
595 }
596
597 /* return matching private key for given public key */
598 static Identity *
lookup_identity(struct sshkey * key)599 lookup_identity(struct sshkey *key)
600 {
601 Identity *id;
602
603 TAILQ_FOREACH(id, &idtab->idlist, next) {
604 if (sshkey_equal(key, id->key))
605 return (id);
606 }
607 return (NULL);
608 }
609
610 /* Check confirmation of keysign request */
611 static int
confirm_key(Identity * id,const char * extra)612 confirm_key(Identity *id, const char *extra)
613 {
614 char *p;
615 int ret = -1;
616
617 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT);
618 if (p != NULL &&
619 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s",
620 id->comment, p,
621 extra == NULL ? "" : "\n", extra == NULL ? "" : extra))
622 ret = 0;
623 free(p);
624
625 return (ret);
626 }
627
628 static void
send_status(SocketEntry * e,int success)629 send_status(SocketEntry *e, int success)
630 {
631 int r;
632
633 if ((r = sshbuf_put_u32(e->output, 1)) != 0 ||
634 (r = sshbuf_put_u8(e->output, success ?
635 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0)
636 fatal_fr(r, "compose");
637 }
638
639 /* send list of supported public keys to 'client' */
640 static void
process_request_identities(SocketEntry * e)641 process_request_identities(SocketEntry *e)
642 {
643 Identity *id;
644 struct sshbuf *msg, *keys;
645 int r;
646 u_int i = 0, nentries = 0;
647 char *fp;
648
649 debug2_f("entering");
650
651 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL)
652 fatal_f("sshbuf_new failed");
653 TAILQ_FOREACH(id, &idtab->idlist, next) {
654 if ((fp = sshkey_fingerprint(id->key, SSH_FP_HASH_DEFAULT,
655 SSH_FP_DEFAULT)) == NULL)
656 fatal_f("fingerprint failed");
657 debug_f("key %u / %u: %s %s", i++, idtab->nentries,
658 sshkey_ssh_name(id->key), fp);
659 dump_dest_constraints(__func__,
660 id->dest_constraints, id->ndest_constraints);
661 free(fp);
662 /* identity not visible, don't include in response */
663 if (identity_permitted(id, e, NULL, NULL, NULL) != 0)
664 continue;
665 if ((r = sshkey_puts_opts(id->key, keys,
666 SSHKEY_SERIALIZE_INFO)) != 0 ||
667 (r = sshbuf_put_cstring(keys, id->comment)) != 0) {
668 error_fr(r, "compose key/comment");
669 continue;
670 }
671 nentries++;
672 }
673 debug2_f("replying with %u allowed of %u available keys",
674 nentries, idtab->nentries);
675 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
676 (r = sshbuf_put_u32(msg, nentries)) != 0 ||
677 (r = sshbuf_putb(msg, keys)) != 0)
678 fatal_fr(r, "compose");
679 if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
680 fatal_fr(r, "enqueue");
681 sshbuf_free(msg);
682 sshbuf_free(keys);
683 }
684
685
686 static char *
agent_decode_alg(struct sshkey * key,u_int flags)687 agent_decode_alg(struct sshkey *key, u_int flags)
688 {
689 if (key->type == KEY_RSA) {
690 if (flags & SSH_AGENT_RSA_SHA2_256)
691 return "rsa-sha2-256";
692 else if (flags & SSH_AGENT_RSA_SHA2_512)
693 return "rsa-sha2-512";
694 } else if (key->type == KEY_RSA_CERT) {
695 if (flags & SSH_AGENT_RSA_SHA2_256)
696 return "rsa-sha2-256-cert-v01@openssh.com";
697 else if (flags & SSH_AGENT_RSA_SHA2_512)
698 return "rsa-sha2-512-cert-v01@openssh.com";
699 }
700 return NULL;
701 }
702
703 /*
704 * Attempt to parse the contents of a buffer as a SSH publickey userauth
705 * request, checking its contents for consistency and matching the embedded
706 * key against the one that is being used for signing.
707 * Note: does not modify msg buffer.
708 * Optionally extract the username, session ID and/or hostkey from the request.
709 */
710 static int
parse_userauth_request(struct sshbuf * msg,const struct sshkey * expected_key,char ** userp,struct sshbuf ** sess_idp,struct sshkey ** hostkeyp)711 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key,
712 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp)
713 {
714 struct sshbuf *b = NULL, *sess_id = NULL;
715 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL;
716 int r;
717 u_char t, sig_follows;
718 struct sshkey *mkey = NULL, *hostkey = NULL;
719
720 if (userp != NULL)
721 *userp = NULL;
722 if (sess_idp != NULL)
723 *sess_idp = NULL;
724 if (hostkeyp != NULL)
725 *hostkeyp = NULL;
726 if ((b = sshbuf_fromb(msg)) == NULL)
727 fatal_f("sshbuf_fromb");
728
729 /* SSH userauth request */
730 if ((r = sshbuf_froms(b, &sess_id)) != 0)
731 goto out;
732 if (sshbuf_len(sess_id) == 0) {
733 r = SSH_ERR_INVALID_FORMAT;
734 goto out;
735 }
736 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */
737 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */
738 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */
739 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */
740 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */
741 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */
742 (r = sshkey_froms(b, &mkey)) != 0) /* key */
743 goto out;
744 if (t != SSH2_MSG_USERAUTH_REQUEST ||
745 sig_follows != 1 ||
746 strcmp(service, "ssh-connection") != 0 ||
747 !sshkey_equal(expected_key, mkey) ||
748 sshkey_type_from_name(pkalg) != expected_key->type) {
749 r = SSH_ERR_INVALID_FORMAT;
750 goto out;
751 }
752 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) {
753 if ((r = sshkey_froms(b, &hostkey)) != 0)
754 goto out;
755 } else if (strcmp(method, "publickey") != 0) {
756 r = SSH_ERR_INVALID_FORMAT;
757 goto out;
758 }
759 if (sshbuf_len(b) != 0) {
760 r = SSH_ERR_INVALID_FORMAT;
761 goto out;
762 }
763 /* success */
764 r = 0;
765 debug3_f("well formed userauth");
766 if (userp != NULL) {
767 *userp = user;
768 user = NULL;
769 }
770 if (sess_idp != NULL) {
771 *sess_idp = sess_id;
772 sess_id = NULL;
773 }
774 if (hostkeyp != NULL) {
775 *hostkeyp = hostkey;
776 hostkey = NULL;
777 }
778 out:
779 sshbuf_free(b);
780 sshbuf_free(sess_id);
781 free(user);
782 free(service);
783 free(method);
784 free(pkalg);
785 sshkey_free(mkey);
786 sshkey_free(hostkey);
787 return r;
788 }
789
790 /*
791 * Attempt to parse the contents of a buffer as a SSHSIG signature request.
792 * Note: does not modify buffer.
793 */
794 static int
parse_sshsig_request(struct sshbuf * msg)795 parse_sshsig_request(struct sshbuf *msg)
796 {
797 int r;
798 struct sshbuf *b;
799
800 if ((b = sshbuf_fromb(msg)) == NULL)
801 fatal_f("sshbuf_fromb");
802
803 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 ||
804 (r = sshbuf_consume(b, 6)) != 0 ||
805 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */
806 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */
807 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */
808 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */
809 goto out;
810 if (sshbuf_len(b) != 0) {
811 r = SSH_ERR_INVALID_FORMAT;
812 goto out;
813 }
814 /* success */
815 r = 0;
816 out:
817 sshbuf_free(b);
818 return r;
819 }
820
821 /*
822 * This function inspects a message to be signed by a FIDO key that has a
823 * web-like application string (i.e. one that does not begin with "ssh:".
824 * It checks that the message is one of those expected for SSH operations
825 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges
826 * for the web.
827 */
828 static int
check_websafe_message_contents(struct sshkey * key,struct sshbuf * data)829 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data)
830 {
831 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) {
832 debug_f("signed data matches public key userauth request");
833 return 1;
834 }
835 if (parse_sshsig_request(data) == 0) {
836 debug_f("signed data matches SSHSIG signature request");
837 return 1;
838 }
839
840 /* XXX check CA signature operation */
841
842 error("web-origin key attempting to sign non-SSH message");
843 return 0;
844 }
845
846 static int
buf_equal(const struct sshbuf * a,const struct sshbuf * b)847 buf_equal(const struct sshbuf *a, const struct sshbuf *b)
848 {
849 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL)
850 return SSH_ERR_INVALID_ARGUMENT;
851 if (sshbuf_len(a) != sshbuf_len(b))
852 return SSH_ERR_INVALID_FORMAT;
853 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0)
854 return SSH_ERR_INVALID_FORMAT;
855 return 0;
856 }
857
858 /* ssh2 only */
859 static void
process_sign_request2(SocketEntry * e)860 process_sign_request2(SocketEntry *e)
861 {
862 u_char *signature = NULL;
863 size_t slen = 0;
864 u_int compat = 0, flags;
865 int r, ok = -1, retried = 0;
866 char *fp = NULL, *pin = NULL, *prompt = NULL;
867 char *user = NULL, *sig_dest = NULL;
868 const char *fwd_host = NULL, *dest_host = NULL;
869 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL;
870 struct sshkey *key = NULL, *hostkey = NULL;
871 struct identity *id;
872 struct notifier_ctx *notifier = NULL;
873
874 debug_f("entering");
875
876 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL)
877 fatal_f("sshbuf_new failed");
878 if ((r = sshkey_froms(e->request, &key)) != 0 ||
879 (r = sshbuf_get_stringb(e->request, data)) != 0 ||
880 (r = sshbuf_get_u32(e->request, &flags)) != 0) {
881 error_fr(r, "parse");
882 goto send;
883 }
884
885 if ((id = lookup_identity(key)) == NULL) {
886 verbose_f("%s key not found", sshkey_type(key));
887 goto send;
888 }
889 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT,
890 SSH_FP_DEFAULT)) == NULL)
891 fatal_f("fingerprint failed");
892
893 if (id->ndest_constraints != 0) {
894 if (e->nsession_ids == 0) {
895 logit_f("refusing use of destination-constrained key "
896 "to sign on unbound connection");
897 goto send;
898 }
899 if (parse_userauth_request(data, key, &user, &sid,
900 &hostkey) != 0) {
901 logit_f("refusing use of destination-constrained key "
902 "to sign an unidentified signature");
903 goto send;
904 }
905 /* XXX logspam */
906 debug_f("user=%s", user);
907 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0)
908 goto send;
909 /* XXX display fwd_host/dest_host in askpass UI */
910 /*
911 * Ensure that the session ID is the most recent one
912 * registered on the socket - it should have been bound by
913 * ssh immediately before userauth.
914 */
915 if (buf_equal(sid,
916 e->session_ids[e->nsession_ids - 1].sid) != 0) {
917 error_f("unexpected session ID (%zu listed) on "
918 "signature request for target user %s with "
919 "key %s %s", e->nsession_ids, user,
920 sshkey_type(id->key), fp);
921 goto send;
922 }
923 /*
924 * Ensure that the hostkey embedded in the signature matches
925 * the one most recently bound to the socket. An exception is
926 * made for the initial forwarding hop.
927 */
928 if (e->nsession_ids > 1 && hostkey == NULL) {
929 error_f("refusing use of destination-constrained key: "
930 "no hostkey recorded in signature for forwarded "
931 "connection");
932 goto send;
933 }
934 if (hostkey != NULL && !sshkey_equal(hostkey,
935 e->session_ids[e->nsession_ids - 1].key)) {
936 error_f("refusing use of destination-constrained key: "
937 "mismatch between hostkey in request and most "
938 "recently bound session");
939 goto send;
940 }
941 xasprintf(&sig_dest, "public key authentication request for "
942 "user \"%s\" to listed host", user);
943 }
944 if (id->confirm && confirm_key(id, sig_dest) != 0) {
945 verbose_f("user refused key");
946 goto send;
947 }
948 if (sshkey_is_sk(id->key)) {
949 if (restrict_websafe &&
950 match_pattern_list(id->key->sk_application,
951 websafe_allowlist, 0) != 1 &&
952 !check_websafe_message_contents(key, data)) {
953 /* error already logged */
954 goto send;
955 }
956 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) {
957 notifier = notify_start(0,
958 "Confirm user presence for key %s %s%s%s",
959 sshkey_type(id->key), fp,
960 sig_dest == NULL ? "" : "\n",
961 sig_dest == NULL ? "" : sig_dest);
962 }
963 }
964 retry_pin:
965 if ((r = sshkey_sign(id->key, &signature, &slen,
966 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags),
967 id->sk_provider, pin, compat)) != 0) {
968 debug_fr(r, "sshkey_sign");
969 if (pin == NULL && !retried && sshkey_is_sk(id->key) &&
970 r == SSH_ERR_KEY_WRONG_PASSPHRASE) {
971 notify_complete(notifier, NULL);
972 notifier = NULL;
973 /* XXX include sig_dest */
974 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ",
975 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ?
976 " and confirm user presence " : " ",
977 sshkey_type(id->key), fp);
978 pin = read_passphrase(prompt, RP_USE_ASKPASS);
979 retried = 1;
980 goto retry_pin;
981 }
982 error_fr(r, "sshkey_sign");
983 goto send;
984 }
985 /* Success */
986 ok = 0;
987 debug_f("good signature");
988 send:
989 notify_complete(notifier, "User presence confirmed");
990
991 if (ok == 0) {
992 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 ||
993 (r = sshbuf_put_string(msg, signature, slen)) != 0)
994 fatal_fr(r, "compose");
995 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
996 fatal_fr(r, "compose failure");
997
998 if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
999 fatal_fr(r, "enqueue");
1000
1001 sshbuf_free(sid);
1002 sshbuf_free(data);
1003 sshbuf_free(msg);
1004 sshkey_free(key);
1005 sshkey_free(hostkey);
1006 free(fp);
1007 free(signature);
1008 free(sig_dest);
1009 free(user);
1010 free(prompt);
1011 if (pin != NULL)
1012 freezero(pin, strlen(pin));
1013 }
1014
1015 /* shared */
1016 static void
process_remove_identity(SocketEntry * e)1017 process_remove_identity(SocketEntry *e)
1018 {
1019 int r, success = 0;
1020 struct sshkey *key = NULL;
1021 Identity *id;
1022
1023 debug2_f("entering");
1024 if ((r = sshkey_froms(e->request, &key)) != 0) {
1025 error_fr(r, "parse key");
1026 goto done;
1027 }
1028 if ((id = lookup_identity(key)) == NULL) {
1029 debug_f("key not found");
1030 goto done;
1031 }
1032 /* identity not visible, cannot be removed */
1033 if (identity_permitted(id, e, NULL, NULL, NULL) != 0)
1034 goto done; /* error already logged */
1035 /* We have this key, free it. */
1036 if (idtab->nentries < 1)
1037 fatal_f("internal error: nentries %d", idtab->nentries);
1038 TAILQ_REMOVE(&idtab->idlist, id, next);
1039 free_identity(id);
1040 idtab->nentries--;
1041 success = 1;
1042 done:
1043 sshkey_free(key);
1044 send_status(e, success);
1045 }
1046
1047 static void
remove_all_identities(void)1048 remove_all_identities(void)
1049 {
1050 Identity *id;
1051
1052 debug2_f("entering");
1053 /* Loop over all identities and clear the keys. */
1054 for (id = TAILQ_FIRST(&idtab->idlist); id;
1055 id = TAILQ_FIRST(&idtab->idlist)) {
1056 TAILQ_REMOVE(&idtab->idlist, id, next);
1057 free_identity(id);
1058 }
1059
1060 /* Mark that there are no identities. */
1061 idtab->nentries = 0;
1062 }
1063
1064 static void
process_remove_all_identities(SocketEntry * e)1065 process_remove_all_identities(SocketEntry *e)
1066 {
1067 remove_all_identities();
1068
1069 /* Send success. */
1070 send_status(e, 1);
1071 }
1072
1073 /* removes expired keys and returns number of seconds until the next expiry */
1074 static time_t
reaper(void)1075 reaper(void)
1076 {
1077 time_t deadline = 0, now = monotime();
1078 Identity *id, *nxt;
1079
1080 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) {
1081 nxt = TAILQ_NEXT(id, next);
1082 if (id->death == 0)
1083 continue;
1084 if (now >= id->death) {
1085 debug("expiring key '%s'", id->comment);
1086 TAILQ_REMOVE(&idtab->idlist, id, next);
1087 free_identity(id);
1088 idtab->nentries--;
1089 } else
1090 deadline = (deadline == 0) ? id->death :
1091 MINIMUM(deadline, id->death);
1092 }
1093 if (deadline == 0 || deadline <= now)
1094 return 0;
1095 else
1096 return (deadline - now);
1097 }
1098
1099 static int
parse_dest_constraint_hop(struct sshbuf * b,struct dest_constraint_hop * dch)1100 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch)
1101 {
1102 u_char key_is_ca;
1103 size_t elen = 0;
1104 int r;
1105 struct sshkey *k = NULL;
1106 char *fp;
1107
1108 memset(dch, '\0', sizeof(*dch));
1109 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 ||
1110 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 ||
1111 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) {
1112 error_fr(r, "parse");
1113 goto out;
1114 }
1115 if (elen != 0) {
1116 error_f("unsupported extensions (len %zu)", elen);
1117 r = SSH_ERR_FEATURE_UNSUPPORTED;
1118 goto out;
1119 }
1120 if (*dch->hostname == '\0') {
1121 free(dch->hostname);
1122 dch->hostname = NULL;
1123 }
1124 if (*dch->user == '\0') {
1125 free(dch->user);
1126 dch->user = NULL;
1127 }
1128 while (sshbuf_len(b) != 0) {
1129 dch->keys = xrecallocarray(dch->keys, dch->nkeys,
1130 dch->nkeys + 1, sizeof(*dch->keys));
1131 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys,
1132 dch->nkeys + 1, sizeof(*dch->key_is_ca));
1133 if ((r = sshkey_froms(b, &k)) != 0 ||
1134 (r = sshbuf_get_u8(b, &key_is_ca)) != 0)
1135 goto out;
1136 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT,
1137 SSH_FP_DEFAULT)) == NULL)
1138 fatal_f("fingerprint failed");
1139 debug3_f("%s%s%s: adding %skey %s %s",
1140 dch->user == NULL ? "" : dch->user,
1141 dch->user == NULL ? "" : "@",
1142 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp);
1143 free(fp);
1144 dch->keys[dch->nkeys] = k;
1145 dch->key_is_ca[dch->nkeys] = key_is_ca != 0;
1146 dch->nkeys++;
1147 k = NULL; /* transferred */
1148 }
1149 /* success */
1150 r = 0;
1151 out:
1152 sshkey_free(k);
1153 return r;
1154 }
1155
1156 static int
parse_dest_constraint(struct sshbuf * m,struct dest_constraint * dc)1157 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc)
1158 {
1159 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL;
1160 int r;
1161 size_t elen = 0;
1162
1163 debug3_f("entering");
1164
1165 memset(dc, '\0', sizeof(*dc));
1166 if ((r = sshbuf_froms(m, &b)) != 0 ||
1167 (r = sshbuf_froms(b, &frombuf)) != 0 ||
1168 (r = sshbuf_froms(b, &tobuf)) != 0 ||
1169 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) {
1170 error_fr(r, "parse");
1171 goto out;
1172 }
1173 if ((r = parse_dest_constraint_hop(frombuf, &dc->from)) != 0 ||
1174 (r = parse_dest_constraint_hop(tobuf, &dc->to)) != 0)
1175 goto out; /* already logged */
1176 if (elen != 0) {
1177 error_f("unsupported extensions (len %zu)", elen);
1178 r = SSH_ERR_FEATURE_UNSUPPORTED;
1179 goto out;
1180 }
1181 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)",
1182 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys,
1183 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "",
1184 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys);
1185 /* check consistency */
1186 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) ||
1187 dc->from.user != NULL) {
1188 error_f("inconsistent \"from\" specification");
1189 r = SSH_ERR_INVALID_FORMAT;
1190 goto out;
1191 }
1192 if (dc->to.hostname == NULL || dc->to.nkeys == 0) {
1193 error_f("incomplete \"to\" specification");
1194 r = SSH_ERR_INVALID_FORMAT;
1195 goto out;
1196 }
1197 /* success */
1198 r = 0;
1199 out:
1200 sshbuf_free(b);
1201 sshbuf_free(frombuf);
1202 sshbuf_free(tobuf);
1203 return r;
1204 }
1205
1206 static int
parse_key_constraint_extension(struct sshbuf * m,char ** sk_providerp,struct dest_constraint ** dcsp,size_t * ndcsp,int * cert_onlyp,struct sshkey *** certs,size_t * ncerts)1207 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp,
1208 struct dest_constraint **dcsp, size_t *ndcsp, int *cert_onlyp,
1209 struct sshkey ***certs, size_t *ncerts)
1210 {
1211 char *ext_name = NULL;
1212 int r;
1213 struct sshbuf *b = NULL;
1214 u_char v;
1215 struct sshkey *k;
1216
1217 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) {
1218 error_fr(r, "parse constraint extension");
1219 goto out;
1220 }
1221 debug_f("constraint ext %s", ext_name);
1222 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) {
1223 if (sk_providerp == NULL) {
1224 error_f("%s not valid here", ext_name);
1225 r = SSH_ERR_INVALID_FORMAT;
1226 goto out;
1227 }
1228 if (*sk_providerp != NULL) {
1229 error_f("%s already set", ext_name);
1230 r = SSH_ERR_INVALID_FORMAT;
1231 goto out;
1232 }
1233 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) {
1234 error_fr(r, "parse %s", ext_name);
1235 goto out;
1236 }
1237 } else if (strcmp(ext_name,
1238 "restrict-destination-v00@openssh.com") == 0) {
1239 if (*dcsp != NULL) {
1240 error_f("%s already set", ext_name);
1241 r = SSH_ERR_INVALID_FORMAT;
1242 goto out;
1243 }
1244 if ((r = sshbuf_froms(m, &b)) != 0) {
1245 error_fr(r, "parse %s outer", ext_name);
1246 goto out;
1247 }
1248 while (sshbuf_len(b) != 0) {
1249 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) {
1250 error_f("too many %s constraints", ext_name);
1251 r = SSH_ERR_INVALID_FORMAT;
1252 goto out;
1253 }
1254 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1,
1255 sizeof(**dcsp));
1256 if ((r = parse_dest_constraint(b,
1257 *dcsp + (*ndcsp)++)) != 0)
1258 goto out; /* error already logged */
1259 }
1260 } else if (strcmp(ext_name,
1261 "associated-certs-v00@openssh.com") == 0) {
1262 if (certs == NULL || ncerts == NULL || cert_onlyp == NULL) {
1263 error_f("%s not valid here", ext_name);
1264 r = SSH_ERR_INVALID_FORMAT;
1265 goto out;
1266 }
1267 if (*certs != NULL) {
1268 error_f("%s already set", ext_name);
1269 r = SSH_ERR_INVALID_FORMAT;
1270 goto out;
1271 }
1272 if ((r = sshbuf_get_u8(m, &v)) != 0 ||
1273 (r = sshbuf_froms(m, &b)) != 0) {
1274 error_fr(r, "parse %s", ext_name);
1275 goto out;
1276 }
1277 *cert_onlyp = v != 0;
1278 while (sshbuf_len(b) != 0) {
1279 if (*ncerts >= AGENT_MAX_EXT_CERTS) {
1280 error_f("too many %s constraints", ext_name);
1281 r = SSH_ERR_INVALID_FORMAT;
1282 goto out;
1283 }
1284 *certs = xrecallocarray(*certs, *ncerts, *ncerts + 1,
1285 sizeof(**certs));
1286 if ((r = sshkey_froms(b, &k)) != 0) {
1287 error_fr(r, "parse key");
1288 goto out;
1289 }
1290 (*certs)[(*ncerts)++] = k;
1291 }
1292 } else {
1293 error_f("unsupported constraint \"%s\"", ext_name);
1294 r = SSH_ERR_FEATURE_UNSUPPORTED;
1295 goto out;
1296 }
1297 /* success */
1298 r = 0;
1299 out:
1300 free(ext_name);
1301 sshbuf_free(b);
1302 return r;
1303 }
1304
1305 static int
parse_key_constraints(struct sshbuf * m,struct sshkey * k,time_t * deathp,u_int * secondsp,int * confirmp,char ** sk_providerp,struct dest_constraint ** dcsp,size_t * ndcsp,int * cert_onlyp,size_t * ncerts,struct sshkey *** certs)1306 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp,
1307 u_int *secondsp, int *confirmp, char **sk_providerp,
1308 struct dest_constraint **dcsp, size_t *ndcsp,
1309 int *cert_onlyp, size_t *ncerts, struct sshkey ***certs)
1310 {
1311 u_char ctype;
1312 int r;
1313 u_int seconds, maxsign = 0;
1314
1315 while (sshbuf_len(m)) {
1316 if ((r = sshbuf_get_u8(m, &ctype)) != 0) {
1317 error_fr(r, "parse constraint type");
1318 goto out;
1319 }
1320 switch (ctype) {
1321 case SSH_AGENT_CONSTRAIN_LIFETIME:
1322 if (*deathp != 0) {
1323 error_f("lifetime already set");
1324 r = SSH_ERR_INVALID_FORMAT;
1325 goto out;
1326 }
1327 if ((r = sshbuf_get_u32(m, &seconds)) != 0) {
1328 error_fr(r, "parse lifetime constraint");
1329 goto out;
1330 }
1331 *deathp = monotime() + seconds;
1332 *secondsp = seconds;
1333 break;
1334 case SSH_AGENT_CONSTRAIN_CONFIRM:
1335 if (*confirmp != 0) {
1336 error_f("confirm already set");
1337 r = SSH_ERR_INVALID_FORMAT;
1338 goto out;
1339 }
1340 *confirmp = 1;
1341 break;
1342 case SSH_AGENT_CONSTRAIN_MAXSIGN:
1343 if (k == NULL) {
1344 error_f("maxsign not valid here");
1345 r = SSH_ERR_INVALID_FORMAT;
1346 goto out;
1347 }
1348 if (maxsign != 0) {
1349 error_f("maxsign already set");
1350 r = SSH_ERR_INVALID_FORMAT;
1351 goto out;
1352 }
1353 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) {
1354 error_fr(r, "parse maxsign constraint");
1355 goto out;
1356 }
1357 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) {
1358 error_fr(r, "enable maxsign");
1359 goto out;
1360 }
1361 break;
1362 case SSH_AGENT_CONSTRAIN_EXTENSION:
1363 if ((r = parse_key_constraint_extension(m,
1364 sk_providerp, dcsp, ndcsp,
1365 cert_onlyp, certs, ncerts)) != 0)
1366 goto out; /* error already logged */
1367 break;
1368 default:
1369 error_f("Unknown constraint %d", ctype);
1370 r = SSH_ERR_FEATURE_UNSUPPORTED;
1371 goto out;
1372 }
1373 }
1374 /* success */
1375 r = 0;
1376 out:
1377 return r;
1378 }
1379
1380 static void
process_add_identity(SocketEntry * e)1381 process_add_identity(SocketEntry *e)
1382 {
1383 Identity *id;
1384 int success = 0, confirm = 0;
1385 char *fp, *comment = NULL, *sk_provider = NULL;
1386 char canonical_provider[PATH_MAX];
1387 time_t death = 0;
1388 u_int seconds = 0;
1389 struct dest_constraint *dest_constraints = NULL;
1390 size_t ndest_constraints = 0;
1391 struct sshkey *k = NULL;
1392 int r = SSH_ERR_INTERNAL_ERROR;
1393
1394 debug2_f("entering");
1395 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 ||
1396 k == NULL ||
1397 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) {
1398 error_fr(r, "parse");
1399 goto out;
1400 }
1401 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm,
1402 &sk_provider, &dest_constraints, &ndest_constraints,
1403 NULL, NULL, NULL) != 0) {
1404 error_f("failed to parse constraints");
1405 sshbuf_reset(e->request);
1406 goto out;
1407 }
1408 dump_dest_constraints(__func__, dest_constraints, ndest_constraints);
1409
1410 if (sk_provider != NULL) {
1411 if (!sshkey_is_sk(k)) {
1412 error("Cannot add provider: %s is not an "
1413 "authenticator-hosted key", sshkey_type(k));
1414 goto out;
1415 }
1416 if (strcasecmp(sk_provider, "internal") == 0) {
1417 debug_f("internal provider");
1418 } else {
1419 if (socket_is_remote(e) && !remote_add_provider) {
1420 verbose("failed add of SK provider \"%.100s\": "
1421 "remote addition of providers is disabled",
1422 sk_provider);
1423 goto out;
1424 }
1425 if (realpath(sk_provider, canonical_provider) == NULL) {
1426 verbose("failed provider \"%.100s\": "
1427 "realpath: %s", sk_provider,
1428 strerror(errno));
1429 goto out;
1430 }
1431 free(sk_provider);
1432 sk_provider = xstrdup(canonical_provider);
1433 if (match_pattern_list(sk_provider,
1434 allowed_providers, 0) != 1) {
1435 error("Refusing add key: "
1436 "provider %s not allowed", sk_provider);
1437 goto out;
1438 }
1439 }
1440 }
1441 if ((r = sshkey_shield_private(k)) != 0) {
1442 error_fr(r, "shield private");
1443 goto out;
1444 }
1445 if (lifetime && !death)
1446 death = monotime() + lifetime;
1447 if ((id = lookup_identity(k)) == NULL) {
1448 id = xcalloc(1, sizeof(Identity));
1449 TAILQ_INSERT_TAIL(&idtab->idlist, id, next);
1450 /* Increment the number of identities. */
1451 idtab->nentries++;
1452 } else {
1453 /* identity not visible, do not update */
1454 if (identity_permitted(id, e, NULL, NULL, NULL) != 0)
1455 goto out; /* error already logged */
1456 /* key state might have been updated */
1457 sshkey_free(id->key);
1458 free(id->comment);
1459 free(id->sk_provider);
1460 free_dest_constraints(id->dest_constraints,
1461 id->ndest_constraints);
1462 }
1463 /* success */
1464 id->key = k;
1465 id->comment = comment;
1466 id->death = death;
1467 id->confirm = confirm;
1468 id->sk_provider = sk_provider;
1469 id->dest_constraints = dest_constraints;
1470 id->ndest_constraints = ndest_constraints;
1471
1472 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT,
1473 SSH_FP_DEFAULT)) == NULL)
1474 fatal_f("sshkey_fingerprint failed");
1475 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) "
1476 "(provider: %s) (destination constraints: %zu)",
1477 sshkey_ssh_name(k), fp, comment, seconds, confirm,
1478 sk_provider == NULL ? "none" : sk_provider, ndest_constraints);
1479 free(fp);
1480 /* transferred */
1481 k = NULL;
1482 comment = NULL;
1483 sk_provider = NULL;
1484 dest_constraints = NULL;
1485 ndest_constraints = 0;
1486 success = 1;
1487 out:
1488 free(sk_provider);
1489 free(comment);
1490 sshkey_free(k);
1491 free_dest_constraints(dest_constraints, ndest_constraints);
1492 send_status(e, success);
1493 }
1494
1495 /* XXX todo: encrypt sensitive data with passphrase */
1496 static void
process_lock_agent(SocketEntry * e,int lock)1497 process_lock_agent(SocketEntry *e, int lock)
1498 {
1499 int r, success = 0, delay;
1500 char *passwd;
1501 u_char passwdhash[LOCK_SIZE];
1502 static u_int fail_count = 0;
1503 size_t pwlen;
1504
1505 debug2_f("entering");
1506 /*
1507 * This is deliberately fatal: the user has requested that we lock,
1508 * but we can't parse their request properly. The only safe thing to
1509 * do is abort.
1510 */
1511 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0)
1512 fatal_fr(r, "parse");
1513 if (pwlen == 0) {
1514 debug("empty password not supported");
1515 } else if (locked && !lock) {
1516 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt),
1517 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0)
1518 fatal("bcrypt_pbkdf");
1519 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) {
1520 debug("agent unlocked");
1521 locked = 0;
1522 fail_count = 0;
1523 explicit_bzero(lock_pwhash, sizeof(lock_pwhash));
1524 success = 1;
1525 } else {
1526 /* delay in 0.1s increments up to 10s */
1527 if (fail_count < 100)
1528 fail_count++;
1529 delay = 100000 * fail_count;
1530 debug("unlock failed, delaying %0.1lf seconds",
1531 (double)delay/1000000);
1532 usleep(delay);
1533 }
1534 explicit_bzero(passwdhash, sizeof(passwdhash));
1535 } else if (!locked && lock) {
1536 debug("agent locked");
1537 locked = 1;
1538 arc4random_buf(lock_salt, sizeof(lock_salt));
1539 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt),
1540 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0)
1541 fatal("bcrypt_pbkdf");
1542 success = 1;
1543 }
1544 freezero(passwd, pwlen);
1545 send_status(e, success);
1546 }
1547
1548 static void
no_identities(SocketEntry * e)1549 no_identities(SocketEntry *e)
1550 {
1551 struct sshbuf *msg;
1552 int r;
1553
1554 if ((msg = sshbuf_new()) == NULL)
1555 fatal_f("sshbuf_new failed");
1556 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
1557 (r = sshbuf_put_u32(msg, 0)) != 0 ||
1558 (r = sshbuf_put_stringb(e->output, msg)) != 0)
1559 fatal_fr(r, "compose");
1560 sshbuf_free(msg);
1561 }
1562
1563 #ifdef ENABLE_PKCS11
1564 /* Add an identity to idlist; takes ownership of 'key' and 'comment' */
1565 static void
add_p11_identity(struct sshkey * key,char * comment,const char * provider,time_t death,u_int confirm,struct dest_constraint * dest_constraints,size_t ndest_constraints)1566 add_p11_identity(struct sshkey *key, char *comment, const char *provider,
1567 time_t death, u_int confirm, struct dest_constraint *dest_constraints,
1568 size_t ndest_constraints)
1569 {
1570 Identity *id;
1571
1572 if (lookup_identity(key) != NULL) {
1573 sshkey_free(key);
1574 free(comment);
1575 return;
1576 }
1577 id = xcalloc(1, sizeof(Identity));
1578 id->key = key;
1579 id->comment = comment;
1580 id->provider = xstrdup(provider);
1581 id->death = death;
1582 id->confirm = confirm;
1583 id->dest_constraints = dup_dest_constraints(dest_constraints,
1584 ndest_constraints);
1585 id->ndest_constraints = ndest_constraints;
1586 TAILQ_INSERT_TAIL(&idtab->idlist, id, next);
1587 idtab->nentries++;
1588 }
1589
1590 static void
process_add_smartcard_key(SocketEntry * e)1591 process_add_smartcard_key(SocketEntry *e)
1592 {
1593 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX];
1594 char **comments = NULL;
1595 int r, i, count = 0, success = 0, confirm = 0;
1596 u_int seconds = 0;
1597 time_t death = 0;
1598 struct sshkey **keys = NULL, *k;
1599 struct dest_constraint *dest_constraints = NULL;
1600 size_t j, ndest_constraints = 0, ncerts = 0;
1601 struct sshkey **certs = NULL;
1602 int cert_only = 0;
1603
1604 debug2_f("entering");
1605 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
1606 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) {
1607 error_fr(r, "parse");
1608 goto send;
1609 }
1610 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm,
1611 NULL, &dest_constraints, &ndest_constraints, &cert_only,
1612 &ncerts, &certs) != 0) {
1613 error_f("failed to parse constraints");
1614 goto send;
1615 }
1616 dump_dest_constraints(__func__, dest_constraints, ndest_constraints);
1617 if (socket_is_remote(e) && !remote_add_provider) {
1618 verbose("failed PKCS#11 add of \"%.100s\": remote addition of "
1619 "providers is disabled", provider);
1620 goto send;
1621 }
1622 if (realpath(provider, canonical_provider) == NULL) {
1623 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s",
1624 provider, strerror(errno));
1625 goto send;
1626 }
1627 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) {
1628 verbose("refusing PKCS#11 add of \"%.100s\": "
1629 "provider not allowed", canonical_provider);
1630 goto send;
1631 }
1632 debug_f("add %.100s", canonical_provider);
1633 if (lifetime && !death)
1634 death = monotime() + lifetime;
1635
1636 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments);
1637 for (i = 0; i < count; i++) {
1638 if (comments[i] == NULL || comments[i][0] == '\0') {
1639 free(comments[i]);
1640 comments[i] = xstrdup(canonical_provider);
1641 }
1642 for (j = 0; j < ncerts; j++) {
1643 if (!sshkey_is_cert(certs[j]))
1644 continue;
1645 if (!sshkey_equal_public(keys[i], certs[j]))
1646 continue;
1647 if (pkcs11_make_cert(keys[i], certs[j], &k) != 0)
1648 continue;
1649 add_p11_identity(k, xstrdup(comments[i]),
1650 canonical_provider, death, confirm,
1651 dest_constraints, ndest_constraints);
1652 success = 1;
1653 }
1654 if (!cert_only && lookup_identity(keys[i]) == NULL) {
1655 add_p11_identity(keys[i], comments[i],
1656 canonical_provider, death, confirm,
1657 dest_constraints, ndest_constraints);
1658 keys[i] = NULL; /* transferred */
1659 comments[i] = NULL; /* transferred */
1660 success = 1;
1661 }
1662 /* XXX update constraints for existing keys */
1663 sshkey_free(keys[i]);
1664 free(comments[i]);
1665 }
1666 send:
1667 free(pin);
1668 free(provider);
1669 free(keys);
1670 free(comments);
1671 free_dest_constraints(dest_constraints, ndest_constraints);
1672 for (j = 0; j < ncerts; j++)
1673 sshkey_free(certs[j]);
1674 free(certs);
1675 send_status(e, success);
1676 }
1677
1678 static void
process_remove_smartcard_key(SocketEntry * e)1679 process_remove_smartcard_key(SocketEntry *e)
1680 {
1681 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX];
1682 int r, success = 0;
1683 Identity *id, *nxt;
1684
1685 debug2_f("entering");
1686 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
1687 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) {
1688 error_fr(r, "parse");
1689 goto send;
1690 }
1691 free(pin);
1692
1693 if (realpath(provider, canonical_provider) == NULL) {
1694 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s",
1695 provider, strerror(errno));
1696 goto send;
1697 }
1698
1699 debug_f("remove %.100s", canonical_provider);
1700 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) {
1701 nxt = TAILQ_NEXT(id, next);
1702 /* Skip file--based keys */
1703 if (id->provider == NULL)
1704 continue;
1705 if (!strcmp(canonical_provider, id->provider)) {
1706 TAILQ_REMOVE(&idtab->idlist, id, next);
1707 free_identity(id);
1708 idtab->nentries--;
1709 }
1710 }
1711 if (pkcs11_del_provider(canonical_provider) == 0)
1712 success = 1;
1713 else
1714 error_f("pkcs11_del_provider failed");
1715 send:
1716 free(provider);
1717 send_status(e, success);
1718 }
1719 #endif /* ENABLE_PKCS11 */
1720
1721 static int
process_ext_session_bind(SocketEntry * e)1722 process_ext_session_bind(SocketEntry *e)
1723 {
1724 int r, sid_match, key_match;
1725 struct sshkey *key = NULL;
1726 struct sshbuf *sid = NULL, *sig = NULL;
1727 char *fp = NULL;
1728 size_t i;
1729 u_char fwd = 0;
1730
1731 debug2_f("entering");
1732 e->session_bind_attempted = 1;
1733 if ((r = sshkey_froms(e->request, &key)) != 0 ||
1734 (r = sshbuf_froms(e->request, &sid)) != 0 ||
1735 (r = sshbuf_froms(e->request, &sig)) != 0 ||
1736 (r = sshbuf_get_u8(e->request, &fwd)) != 0) {
1737 error_fr(r, "parse");
1738 goto out;
1739 }
1740 if (sshbuf_len(sid) > AGENT_MAX_SID_LEN) {
1741 error_f("session ID too long");
1742 goto out;
1743 }
1744 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT,
1745 SSH_FP_DEFAULT)) == NULL)
1746 fatal_f("fingerprint failed");
1747 /* check signature with hostkey on session ID */
1748 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig),
1749 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) {
1750 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp);
1751 goto out;
1752 }
1753 /* check whether sid/key already recorded */
1754 for (i = 0; i < e->nsession_ids; i++) {
1755 if (!e->session_ids[i].forwarded) {
1756 error_f("attempt to bind session ID to socket "
1757 "previously bound for authentication attempt");
1758 r = -1;
1759 goto out;
1760 }
1761 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0;
1762 key_match = sshkey_equal(key, e->session_ids[i].key);
1763 if (sid_match && key_match) {
1764 debug_f("session ID already recorded for %s %s",
1765 sshkey_type(key), fp);
1766 r = 0;
1767 goto out;
1768 } else if (sid_match) {
1769 error_f("session ID recorded against different key "
1770 "for %s %s", sshkey_type(key), fp);
1771 r = -1;
1772 goto out;
1773 }
1774 /*
1775 * new sid with previously-seen key can happen, e.g. multiple
1776 * connections to the same host.
1777 */
1778 }
1779 /* record new key/sid */
1780 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) {
1781 error_f("too many session IDs recorded");
1782 r = -1;
1783 goto out;
1784 }
1785 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids,
1786 e->nsession_ids + 1, sizeof(*e->session_ids));
1787 i = e->nsession_ids++;
1788 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i,
1789 AGENT_MAX_SESSION_IDS);
1790 e->session_ids[i].key = key;
1791 e->session_ids[i].forwarded = fwd != 0;
1792 key = NULL; /* transferred */
1793 /* can't transfer sid; it's refcounted and scoped to request's life */
1794 if ((e->session_ids[i].sid = sshbuf_new()) == NULL)
1795 fatal_f("sshbuf_new");
1796 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0)
1797 fatal_fr(r, "sshbuf_putb session ID");
1798 /* success */
1799 r = 0;
1800 out:
1801 free(fp);
1802 sshkey_free(key);
1803 sshbuf_free(sid);
1804 sshbuf_free(sig);
1805 return r == 0 ? 1 : 0;
1806 }
1807
1808 static void
process_extension(SocketEntry * e)1809 process_extension(SocketEntry *e)
1810 {
1811 int r, success = 0;
1812 char *name;
1813
1814 debug2_f("entering");
1815 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) {
1816 error_fr(r, "parse");
1817 goto send;
1818 }
1819 if (strcmp(name, "session-bind@openssh.com") == 0)
1820 success = process_ext_session_bind(e);
1821 else
1822 debug_f("unsupported extension \"%s\"", name);
1823 free(name);
1824 send:
1825 send_status(e, success);
1826 }
1827 /*
1828 * dispatch incoming message.
1829 * returns 1 on success, 0 for incomplete messages or -1 on error.
1830 */
1831 static int
process_message(u_int socknum)1832 process_message(u_int socknum)
1833 {
1834 u_int msg_len;
1835 u_char type;
1836 const u_char *cp;
1837 int r;
1838 SocketEntry *e;
1839
1840 if (socknum >= sockets_alloc)
1841 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc);
1842 e = &sockets[socknum];
1843
1844 if (sshbuf_len(e->input) < 5)
1845 return 0; /* Incomplete message header. */
1846 cp = sshbuf_ptr(e->input);
1847 msg_len = PEEK_U32(cp);
1848 if (msg_len > AGENT_MAX_LEN) {
1849 debug_f("socket %u (fd=%d) message too long %u > %u",
1850 socknum, e->fd, msg_len, AGENT_MAX_LEN);
1851 return -1;
1852 }
1853 if (sshbuf_len(e->input) < msg_len + 4)
1854 return 0; /* Incomplete message body. */
1855
1856 /* move the current input to e->request */
1857 sshbuf_reset(e->request);
1858 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 ||
1859 (r = sshbuf_get_u8(e->request, &type)) != 0) {
1860 if (r == SSH_ERR_MESSAGE_INCOMPLETE ||
1861 r == SSH_ERR_STRING_TOO_LARGE) {
1862 error_fr(r, "parse");
1863 return -1;
1864 }
1865 fatal_fr(r, "parse");
1866 }
1867
1868 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type);
1869
1870 /* check whether agent is locked */
1871 if (locked && type != SSH_AGENTC_UNLOCK) {
1872 sshbuf_reset(e->request);
1873 switch (type) {
1874 case SSH2_AGENTC_REQUEST_IDENTITIES:
1875 /* send empty lists */
1876 no_identities(e);
1877 break;
1878 default:
1879 /* send a fail message for all other request types */
1880 send_status(e, 0);
1881 }
1882 return 1;
1883 }
1884
1885 switch (type) {
1886 case SSH_AGENTC_LOCK:
1887 case SSH_AGENTC_UNLOCK:
1888 process_lock_agent(e, type == SSH_AGENTC_LOCK);
1889 break;
1890 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
1891 process_remove_all_identities(e); /* safe for !WITH_SSH1 */
1892 break;
1893 /* ssh2 */
1894 case SSH2_AGENTC_SIGN_REQUEST:
1895 process_sign_request2(e);
1896 break;
1897 case SSH2_AGENTC_REQUEST_IDENTITIES:
1898 process_request_identities(e);
1899 break;
1900 case SSH2_AGENTC_ADD_IDENTITY:
1901 case SSH2_AGENTC_ADD_ID_CONSTRAINED:
1902 process_add_identity(e);
1903 break;
1904 case SSH2_AGENTC_REMOVE_IDENTITY:
1905 process_remove_identity(e);
1906 break;
1907 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
1908 process_remove_all_identities(e);
1909 break;
1910 #ifdef ENABLE_PKCS11
1911 case SSH_AGENTC_ADD_SMARTCARD_KEY:
1912 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
1913 process_add_smartcard_key(e);
1914 break;
1915 case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
1916 process_remove_smartcard_key(e);
1917 break;
1918 #endif /* ENABLE_PKCS11 */
1919 case SSH_AGENTC_EXTENSION:
1920 process_extension(e);
1921 break;
1922 default:
1923 /* Unknown message. Respond with failure. */
1924 error("Unknown message %d", type);
1925 sshbuf_reset(e->request);
1926 send_status(e, 0);
1927 break;
1928 }
1929 return 1;
1930 }
1931
1932 static void
new_socket(sock_type type,int fd)1933 new_socket(sock_type type, int fd)
1934 {
1935 u_int i, old_alloc, new_alloc;
1936
1937 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" :
1938 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN"));
1939 if (type == AUTH_CONNECTION) {
1940 debug("xcount %d -> %d", xcount, xcount + 1);
1941 ++xcount;
1942 }
1943 set_nonblock(fd);
1944
1945 if (fd > max_fd)
1946 max_fd = fd;
1947
1948 for (i = 0; i < sockets_alloc; i++)
1949 if (sockets[i].type == AUTH_UNUSED) {
1950 sockets[i].fd = fd;
1951 if ((sockets[i].input = sshbuf_new()) == NULL ||
1952 (sockets[i].output = sshbuf_new()) == NULL ||
1953 (sockets[i].request = sshbuf_new()) == NULL)
1954 fatal_f("sshbuf_new failed");
1955 sockets[i].type = type;
1956 return;
1957 }
1958 old_alloc = sockets_alloc;
1959 new_alloc = sockets_alloc + 10;
1960 sockets = xrecallocarray(sockets, old_alloc, new_alloc,
1961 sizeof(sockets[0]));
1962 for (i = old_alloc; i < new_alloc; i++)
1963 sockets[i].type = AUTH_UNUSED;
1964 sockets_alloc = new_alloc;
1965 sockets[old_alloc].fd = fd;
1966 if ((sockets[old_alloc].input = sshbuf_new()) == NULL ||
1967 (sockets[old_alloc].output = sshbuf_new()) == NULL ||
1968 (sockets[old_alloc].request = sshbuf_new()) == NULL)
1969 fatal_f("sshbuf_new failed");
1970 sockets[old_alloc].type = type;
1971 }
1972
1973 static int
handle_socket_read(u_int socknum)1974 handle_socket_read(u_int socknum)
1975 {
1976 struct sockaddr_un sunaddr;
1977 socklen_t slen;
1978 uid_t euid;
1979 gid_t egid;
1980 int fd;
1981
1982 slen = sizeof(sunaddr);
1983 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen);
1984 if (fd == -1) {
1985 error("accept from AUTH_SOCKET: %s", strerror(errno));
1986 return -1;
1987 }
1988 if (getpeereid(fd, &euid, &egid) == -1) {
1989 error("getpeereid %d failed: %s", fd, strerror(errno));
1990 close(fd);
1991 return -1;
1992 }
1993 if ((euid != 0) && (getuid() != euid)) {
1994 error("uid mismatch: peer euid %u != uid %u",
1995 (u_int) euid, (u_int) getuid());
1996 close(fd);
1997 return -1;
1998 }
1999 new_socket(AUTH_CONNECTION, fd);
2000 return 0;
2001 }
2002
2003 static int
handle_conn_read(u_int socknum)2004 handle_conn_read(u_int socknum)
2005 {
2006 char buf[AGENT_RBUF_LEN];
2007 ssize_t len;
2008 int r;
2009
2010 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) {
2011 if (len == -1) {
2012 if (errno == EAGAIN || errno == EINTR)
2013 return 0;
2014 error_f("read error on socket %u (fd %d): %s",
2015 socknum, sockets[socknum].fd, strerror(errno));
2016 }
2017 return -1;
2018 }
2019 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0)
2020 fatal_fr(r, "compose");
2021 explicit_bzero(buf, sizeof(buf));
2022 for (;;) {
2023 if ((r = process_message(socknum)) == -1)
2024 return -1;
2025 else if (r == 0)
2026 break;
2027 }
2028 return 0;
2029 }
2030
2031 static int
handle_conn_write(u_int socknum)2032 handle_conn_write(u_int socknum)
2033 {
2034 ssize_t len;
2035 int r;
2036
2037 if (sshbuf_len(sockets[socknum].output) == 0)
2038 return 0; /* shouldn't happen */
2039 if ((len = write(sockets[socknum].fd,
2040 sshbuf_ptr(sockets[socknum].output),
2041 sshbuf_len(sockets[socknum].output))) <= 0) {
2042 if (len == -1) {
2043 if (errno == EAGAIN || errno == EINTR)
2044 return 0;
2045 error_f("read error on socket %u (fd %d): %s",
2046 socknum, sockets[socknum].fd, strerror(errno));
2047 }
2048 return -1;
2049 }
2050 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0)
2051 fatal_fr(r, "consume");
2052 return 0;
2053 }
2054
2055 static void
after_poll(struct pollfd * pfd,size_t npfd,u_int maxfds)2056 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds)
2057 {
2058 size_t i;
2059 u_int socknum, activefds = npfd;
2060
2061 for (i = 0; i < npfd; i++) {
2062 if (pfd[i].revents == 0)
2063 continue;
2064 /* Find sockets entry */
2065 for (socknum = 0; socknum < sockets_alloc; socknum++) {
2066 if (sockets[socknum].type != AUTH_SOCKET &&
2067 sockets[socknum].type != AUTH_CONNECTION)
2068 continue;
2069 if (pfd[i].fd == sockets[socknum].fd)
2070 break;
2071 }
2072 if (socknum >= sockets_alloc) {
2073 error_f("no socket for fd %d", pfd[i].fd);
2074 continue;
2075 }
2076 /* Process events */
2077 switch (sockets[socknum].type) {
2078 case AUTH_SOCKET:
2079 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0)
2080 break;
2081 if (npfd > maxfds) {
2082 debug3("out of fds (active %u >= limit %u); "
2083 "skipping accept", activefds, maxfds);
2084 break;
2085 }
2086 if (handle_socket_read(socknum) == 0)
2087 activefds++;
2088 break;
2089 case AUTH_CONNECTION:
2090 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 &&
2091 handle_conn_read(socknum) != 0)
2092 goto close_sock;
2093 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 &&
2094 handle_conn_write(socknum) != 0) {
2095 close_sock:
2096 if (activefds == 0)
2097 fatal("activefds == 0 at close_sock");
2098 close_socket(&sockets[socknum]);
2099 activefds--;
2100 break;
2101 }
2102 break;
2103 default:
2104 break;
2105 }
2106 }
2107 }
2108
2109 static int
prepare_poll(struct pollfd ** pfdp,size_t * npfdp,struct timespec * timeoutp,u_int maxfds)2110 prepare_poll(struct pollfd **pfdp, size_t *npfdp, struct timespec *timeoutp, u_int maxfds)
2111 {
2112 struct pollfd *pfd = *pfdp;
2113 size_t i, j, npfd = 0;
2114 time_t deadline;
2115 int r;
2116
2117 /* Count active sockets */
2118 for (i = 0; i < sockets_alloc; i++) {
2119 switch (sockets[i].type) {
2120 case AUTH_SOCKET:
2121 case AUTH_CONNECTION:
2122 npfd++;
2123 break;
2124 case AUTH_UNUSED:
2125 break;
2126 default:
2127 fatal("Unknown socket type %d", sockets[i].type);
2128 break;
2129 }
2130 }
2131 if (npfd != *npfdp &&
2132 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL)
2133 fatal_f("recallocarray failed");
2134 *pfdp = pfd;
2135 *npfdp = npfd;
2136
2137 for (i = j = 0; i < sockets_alloc; i++) {
2138 switch (sockets[i].type) {
2139 case AUTH_SOCKET:
2140 if (npfd > maxfds) {
2141 debug3("out of fds (active %zu >= limit %u); "
2142 "skipping arming listener", npfd, maxfds);
2143 break;
2144 }
2145 pfd[j].fd = sockets[i].fd;
2146 pfd[j].revents = 0;
2147 pfd[j].events = POLLIN;
2148 j++;
2149 break;
2150 case AUTH_CONNECTION:
2151 pfd[j].fd = sockets[i].fd;
2152 pfd[j].revents = 0;
2153 /*
2154 * Only prepare to read if we can handle a full-size
2155 * input read buffer and enqueue a max size reply..
2156 */
2157 if ((r = sshbuf_check_reserve(sockets[i].input,
2158 AGENT_RBUF_LEN)) == 0 &&
2159 (r = sshbuf_check_reserve(sockets[i].output,
2160 AGENT_MAX_LEN)) == 0)
2161 pfd[j].events = POLLIN;
2162 else if (r != SSH_ERR_NO_BUFFER_SPACE)
2163 fatal_fr(r, "reserve");
2164 if (sshbuf_len(sockets[i].output) > 0)
2165 pfd[j].events |= POLLOUT;
2166 j++;
2167 break;
2168 default:
2169 break;
2170 }
2171 }
2172 deadline = reaper();
2173 if (parent_alive_interval != 0)
2174 deadline = (deadline == 0) ? parent_alive_interval :
2175 MINIMUM(deadline, parent_alive_interval);
2176 if (deadline != 0)
2177 ptimeout_deadline_sec(timeoutp, deadline);
2178 return (1);
2179 }
2180
2181 static void
cleanup_socket(void)2182 cleanup_socket(void)
2183 {
2184 if (cleanup_pid != 0 && getpid() != cleanup_pid)
2185 return;
2186 debug_f("cleanup");
2187 if (socket_name[0])
2188 unlink(socket_name);
2189 if (socket_dir[0])
2190 rmdir(socket_dir);
2191 }
2192
2193 void
cleanup_exit(int i)2194 cleanup_exit(int i)
2195 {
2196 cleanup_socket();
2197 #ifdef ENABLE_PKCS11
2198 pkcs11_terminate();
2199 #endif
2200 _exit(i);
2201 }
2202
2203 static void
cleanup_handler(int sig)2204 cleanup_handler(int sig)
2205 {
2206 signalled_exit = sig;
2207 }
2208
2209 static void
keydrop_handler(int sig)2210 keydrop_handler(int sig)
2211 {
2212 signalled_keydrop = sig;
2213 }
2214
2215 static void
check_parent_exists(void)2216 check_parent_exists(void)
2217 {
2218 /*
2219 * If our parent has exited then getppid() will return (pid_t)1,
2220 * so testing for that should be safe.
2221 */
2222 if (parent_pid != -1 && getppid() != parent_pid) {
2223 /* printf("Parent has died - Authentication agent exiting.\n"); */
2224 cleanup_socket();
2225 _exit(2);
2226 }
2227 }
2228
2229 static void
usage(void)2230 usage(void)
2231 {
2232 fprintf(stderr,
2233 "usage: ssh-agent [-c | -s] [-Ddx] [-a bind_address] [-E fingerprint_hash]\n"
2234 " [-O option] [-P allowed_providers] [-t life]\n"
2235 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-O option]\n"
2236 " [-P allowed_providers] [-t life] command [arg ...]\n"
2237 " ssh-agent [-c | -s] -k\n");
2238 exit(1);
2239 }
2240
2241 int
main(int ac,char ** av)2242 main(int ac, char **av)
2243 {
2244 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0;
2245 int sock = -1, ch, result, saved_errno;
2246 char *shell, *format, *fdstr, *pidstr, *agentsocket = NULL;
2247 const char *errstr = NULL;
2248 const char *ccp;
2249 #ifdef HAVE_SETRLIMIT
2250 struct rlimit rlim;
2251 #endif
2252 extern int optind;
2253 extern char *optarg;
2254 pid_t pid;
2255 char pidstrbuf[1 + 3 * sizeof pid];
2256 size_t len;
2257 mode_t prev_mask;
2258 struct timespec timeout;
2259 struct pollfd *pfd = NULL;
2260 size_t npfd = 0;
2261 u_int maxfds;
2262 sigset_t nsigset, osigset;
2263
2264 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
2265 sanitise_stdfd();
2266
2267 /* drop */
2268 (void)setegid(getgid());
2269 (void)setgid(getgid());
2270 setuid(geteuid());
2271
2272 platform_disable_tracing(0); /* strict=no */
2273
2274 #ifdef RLIMIT_NOFILE
2275 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1)
2276 fatal("%s: getrlimit: %s", __progname, strerror(errno));
2277 #endif
2278
2279 __progname = ssh_get_progname(av[0]);
2280 seed_rng();
2281
2282 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:x")) != -1) {
2283 switch (ch) {
2284 case 'E':
2285 fingerprint_hash = ssh_digest_alg_by_name(optarg);
2286 if (fingerprint_hash == -1)
2287 fatal("Invalid hash algorithm \"%s\"", optarg);
2288 break;
2289 case 'c':
2290 if (s_flag)
2291 usage();
2292 c_flag++;
2293 break;
2294 case 'k':
2295 k_flag++;
2296 break;
2297 case 'O':
2298 if (strcmp(optarg, "no-restrict-websafe") == 0)
2299 restrict_websafe = 0;
2300 else if (strcmp(optarg, "allow-remote-pkcs11") == 0)
2301 remote_add_provider = 1;
2302 else if ((ccp = strprefix(optarg,
2303 "websafe-allow=", 0)) != NULL) {
2304 if (websafe_allowlist != NULL)
2305 fatal("websafe-allow already set");
2306 websafe_allowlist = xstrdup(ccp);
2307 } else
2308 fatal("Unknown -O option");
2309 break;
2310 case 'P':
2311 if (allowed_providers != NULL)
2312 fatal("-P option already specified");
2313 allowed_providers = xstrdup(optarg);
2314 break;
2315 case 's':
2316 if (c_flag)
2317 usage();
2318 s_flag++;
2319 break;
2320 case 'd':
2321 if (d_flag || D_flag)
2322 usage();
2323 d_flag++;
2324 break;
2325 case 'D':
2326 if (d_flag || D_flag)
2327 usage();
2328 D_flag++;
2329 break;
2330 case 'a':
2331 agentsocket = optarg;
2332 break;
2333 case 't':
2334 if ((lifetime = convtime(optarg)) == -1) {
2335 fprintf(stderr, "Invalid lifetime\n");
2336 usage();
2337 }
2338 break;
2339 case 'x':
2340 xcount = 0;
2341 break;
2342 default:
2343 usage();
2344 }
2345 }
2346 ac -= optind;
2347 av += optind;
2348
2349 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag))
2350 usage();
2351
2352 if (allowed_providers == NULL)
2353 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS);
2354 if (websafe_allowlist == NULL)
2355 websafe_allowlist = xstrdup(DEFAULT_WEBSAFE_ALLOWLIST);
2356
2357 if (ac == 0 && !c_flag && !s_flag) {
2358 shell = getenv("SHELL");
2359 if (shell != NULL && (len = strlen(shell)) > 2 &&
2360 strncmp(shell + len - 3, "csh", 3) == 0)
2361 c_flag = 1;
2362 }
2363 if (k_flag) {
2364 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
2365 if (pidstr == NULL) {
2366 fprintf(stderr, "%s not set, cannot kill agent\n",
2367 SSH_AGENTPID_ENV_NAME);
2368 exit(1);
2369 }
2370 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
2371 if (errstr) {
2372 fprintf(stderr,
2373 "%s=\"%s\", which is not a good PID: %s\n",
2374 SSH_AGENTPID_ENV_NAME, pidstr, errstr);
2375 exit(1);
2376 }
2377 if (kill(pid, SIGTERM) == -1) {
2378 perror("kill");
2379 exit(1);
2380 }
2381 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
2382 printf(format, SSH_AUTHSOCKET_ENV_NAME);
2383 printf(format, SSH_AGENTPID_ENV_NAME);
2384 printf("echo Agent pid %ld killed;\n", (long)pid);
2385 exit(0);
2386 }
2387
2388 /*
2389 * Minimum file descriptors:
2390 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) +
2391 * a few spare for libc / stack protectors / sanitisers, etc.
2392 */
2393 #define SSH_AGENT_MIN_FDS (3+1+1+1+4)
2394 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS)
2395 fatal("%s: file descriptor rlimit %lld too low (minimum %u)",
2396 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS);
2397 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS;
2398
2399 parent_pid = getpid();
2400
2401 /* Has the socket been provided via socket activation? */
2402 if (agentsocket == NULL && ac == 0 && (d_flag || D_flag) &&
2403 (pidstr = getenv("LISTEN_PID")) != NULL &&
2404 (fdstr = getenv("LISTEN_FDS")) != NULL) {
2405 if (strcmp(fdstr, "1") != 0) {
2406 fatal("unexpected LISTEN_FDS contents "
2407 "(want: \"1\" got\"%s\"", fdstr);
2408 }
2409 if (fcntl(3, F_GETFL) == -1)
2410 fatal("LISTEN_FDS set but fd 3 unavailable");
2411 pid = (int)strtonum(pidstr, 1, INT_MAX, &errstr);
2412 if (errstr != NULL)
2413 fatal("invalid LISTEN_PID: %s", errstr);
2414 if (pid != getpid())
2415 fatal("bad LISTEN_PID: %d vs pid %d", pid, getpid());
2416 debug("using socket activation on fd=3");
2417 sock = 3;
2418 }
2419
2420 /* Otherwise, create private directory for agent socket */
2421 if (sock == -1) {
2422 if (agentsocket == NULL) {
2423 mktemp_proto(socket_dir, sizeof(socket_dir));
2424 if (mkdtemp(socket_dir) == NULL) {
2425 perror("mkdtemp: private socket dir");
2426 exit(1);
2427 }
2428 snprintf(socket_name, sizeof socket_name,
2429 "%s/agent.%ld", socket_dir,
2430 (long)parent_pid);
2431 } else {
2432 /* Try to use specified agent socket */
2433 socket_dir[0] = '\0';
2434 strlcpy(socket_name, agentsocket, sizeof socket_name);
2435 }
2436 }
2437
2438 closefrom(sock == -1 ? STDERR_FILENO + 1 : sock + 1);
2439
2440 /*
2441 * Create socket early so it will exist before command gets run from
2442 * the parent.
2443 */
2444 if (sock == -1) {
2445 prev_mask = umask(0177);
2446 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0);
2447 if (sock < 0) {
2448 /* XXX - unix_listener() calls error() not perror() */
2449 *socket_name = '\0'; /* Don't unlink existing file */
2450 cleanup_exit(1);
2451 }
2452 umask(prev_mask);
2453 }
2454
2455 /*
2456 * Fork, and have the parent execute the command, if any, or present
2457 * the socket data. The child continues as the authentication agent.
2458 */
2459 if (D_flag || d_flag) {
2460 log_init(__progname,
2461 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO,
2462 SYSLOG_FACILITY_AUTH, 1);
2463 if (socket_name[0] != '\0') {
2464 format = c_flag ?
2465 "setenv %s %s;\n" : "%s=%s; export %s;\n";
2466 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
2467 SSH_AUTHSOCKET_ENV_NAME);
2468 printf("echo Agent pid %ld;\n", (long)parent_pid);
2469 fflush(stdout);
2470 }
2471 goto skip;
2472 }
2473 pid = fork();
2474 if (pid == -1) {
2475 perror("fork");
2476 cleanup_exit(1);
2477 }
2478 if (pid != 0) { /* Parent - execute the given command. */
2479 close(sock);
2480 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
2481 if (ac == 0) {
2482 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
2483 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
2484 SSH_AUTHSOCKET_ENV_NAME);
2485 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
2486 SSH_AGENTPID_ENV_NAME);
2487 printf("echo Agent pid %ld;\n", (long)pid);
2488 exit(0);
2489 }
2490 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
2491 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
2492 perror("setenv");
2493 exit(1);
2494 }
2495 execvp(av[0], av);
2496 perror(av[0]);
2497 exit(1);
2498 }
2499 /* child */
2500 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
2501
2502 if (setsid() == -1) {
2503 error("setsid: %s", strerror(errno));
2504 cleanup_exit(1);
2505 }
2506
2507 (void)chdir("/");
2508 if (stdfd_devnull(1, 1, 1) == -1)
2509 error_f("stdfd_devnull failed");
2510
2511 #ifdef HAVE_SETRLIMIT
2512 /* deny core dumps, since memory contains unencrypted private keys */
2513 rlim.rlim_cur = rlim.rlim_max = 0;
2514 if (setrlimit(RLIMIT_CORE, &rlim) == -1) {
2515 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
2516 cleanup_exit(1);
2517 }
2518 #endif
2519
2520 skip:
2521
2522 cleanup_pid = getpid();
2523
2524 #ifdef ENABLE_PKCS11
2525 pkcs11_init(0);
2526 #endif
2527 new_socket(AUTH_SOCKET, sock);
2528 if (ac > 0)
2529 parent_alive_interval = 10;
2530 idtab_init();
2531 ssh_signal(SIGPIPE, SIG_IGN);
2532 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN);
2533 ssh_signal(SIGHUP, cleanup_handler);
2534 ssh_signal(SIGTERM, cleanup_handler);
2535 ssh_signal(SIGUSR1, keydrop_handler);
2536
2537 sigemptyset(&nsigset);
2538 sigaddset(&nsigset, SIGINT);
2539 sigaddset(&nsigset, SIGHUP);
2540 sigaddset(&nsigset, SIGTERM);
2541 sigaddset(&nsigset, SIGUSR1);
2542
2543 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1)
2544 fatal("%s: pledge: %s", __progname, strerror(errno));
2545 platform_pledge_agent();
2546
2547 while (1) {
2548 sigprocmask(SIG_BLOCK, &nsigset, &osigset);
2549 if (signalled_exit != 0) {
2550 logit("exiting on signal %d", (int)signalled_exit);
2551 cleanup_exit(2);
2552 }
2553 if (signalled_keydrop) {
2554 logit("signal %d received; removing all keys",
2555 signalled_keydrop);
2556 remove_all_identities();
2557 signalled_keydrop = 0;
2558 }
2559 ptimeout_init(&timeout);
2560 prepare_poll(&pfd, &npfd, &timeout, maxfds);
2561 result = ppoll(pfd, npfd, ptimeout_get_tsp(&timeout), &osigset);
2562 sigprocmask(SIG_SETMASK, &osigset, NULL);
2563 saved_errno = errno;
2564 if (parent_alive_interval != 0)
2565 check_parent_exists();
2566 (void) reaper(); /* remove expired keys */
2567 if (result == -1) {
2568 if (saved_errno == EINTR)
2569 continue;
2570 fatal("poll: %s", strerror(saved_errno));
2571 } else if (result > 0)
2572 after_poll(pfd, npfd, maxfds);
2573 }
2574 /* NOTREACHED */
2575 }
2576