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igc: disable hw.igc.sbp
[freebsd/src.git] / crypto / openssh / ssh-agent.c
blob67fa376a36ff8bf8c467044bb84b51b4c3743a26
1 /* $OpenBSD: ssh-agent.c,v 1.306 2024/03/09 05:12:13 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
98 /* Maximum accepted message length */
99 #define AGENT_MAX_LEN (256*1024)
100 /* Maximum bytes to read from client socket */
101 #define AGENT_RBUF_LEN (4096)
102 /* Maximum number of recorded session IDs/hostkeys per connection */
103 #define AGENT_MAX_SESSION_IDS 16
104 /* Maximum size of session ID */
105 #define AGENT_MAX_SID_LEN 128
106 /* Maximum number of destination constraints to accept on a key */
107 #define AGENT_MAX_DEST_CONSTRAINTS 1024
108 /* Maximum number of associated certificate constraints to accept on a key */
109 #define AGENT_MAX_EXT_CERTS 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 int session_bind_attempted;
134 } SocketEntry;
135
136 u_int sockets_alloc = 0;
137 SocketEntry *sockets = NULL;
138
139 typedef struct identity {
140 TAILQ_ENTRY(identity) next;
141 struct sshkey *key;
142 char *comment;
143 char *provider;
144 time_t death;
145 u_int confirm;
146 char *sk_provider;
147 struct dest_constraint *dest_constraints;
148 size_t ndest_constraints;
149 } Identity;
150
151 struct idtable {
152 int nentries;
153 TAILQ_HEAD(idqueue, identity) idlist;
154 };
155
156 /* private key table */
157 struct idtable *idtab;
158
159 int max_fd = 0;
160
161 /* pid of shell == parent of agent */
162 pid_t parent_pid = -1;
163 time_t parent_alive_interval = 0;
164
165 sig_atomic_t signalled = 0;
166
167 /* pid of process for which cleanup_socket is applicable */
168 pid_t cleanup_pid = 0;
169
170 /* pathname and directory for AUTH_SOCKET */
171 char socket_name[PATH_MAX];
172 char socket_dir[PATH_MAX];
173
174 /* Pattern-list of allowed PKCS#11/Security key paths */
175 static char *allowed_providers;
176
177 /*
178 * Allows PKCS11 providers or SK keys that use non-internal providers to
179 * be added over a remote connection (identified by session-bind@openssh.com).
180 */
181 static int remote_add_provider;
182
183 /* locking */
184 #define LOCK_SIZE 32
185 #define LOCK_SALT_SIZE 16
186 #define LOCK_ROUNDS 1
187 int locked = 0;
188 u_char lock_pwhash[LOCK_SIZE];
189 u_char lock_salt[LOCK_SALT_SIZE];
190
191 extern char *__progname;
192
193 /* Default lifetime in seconds (0 == forever) */
194 static int lifetime = 0;
195
196 static int fingerprint_hash = SSH_FP_HASH_DEFAULT;
197
198 /* Refuse signing of non-SSH messages for web-origin FIDO keys */
199 static int restrict_websafe = 1;
200
201 /*
202 * Client connection count; incremented in new_socket() and decremented in
203 * close_socket(). When it reaches 0, ssh-agent will exit. Since it is
204 * normally initialized to 1, it will never reach 0. However, if the -x
205 * option is specified, it is initialized to 0 in main(); in that case,
206 * ssh-agent will exit as soon as it has had at least one client but no
207 * longer has any.
208 */
209 static int xcount = 1;
210
211 static void
212 close_socket(SocketEntry *e)
213 {
214 size_t i;
215 int last = 0;
216
217 if (e->type == AUTH_CONNECTION) {
218 debug("xcount %d -> %d", xcount, xcount - 1);
219 if (--xcount == 0)
220 last = 1;
221 }
222 close(e->fd);
223 sshbuf_free(e->input);
224 sshbuf_free(e->output);
225 sshbuf_free(e->request);
226 for (i = 0; i < e->nsession_ids; i++) {
227 sshkey_free(e->session_ids[i].key);
228 sshbuf_free(e->session_ids[i].sid);
229 }
230 free(e->session_ids);
231 memset(e, '\0', sizeof(*e));
232 e->fd = -1;
233 e->type = AUTH_UNUSED;
234 if (last)
235 cleanup_exit(0);
236 }
237
238 static void
239 idtab_init(void)
240 {
241 idtab = xcalloc(1, sizeof(*idtab));
242 TAILQ_INIT(&idtab->idlist);
243 idtab->nentries = 0;
244 }
245
246 static void
247 free_dest_constraint_hop(struct dest_constraint_hop *dch)
248 {
249 u_int i;
250
251 if (dch == NULL)
252 return;
253 free(dch->user);
254 free(dch->hostname);
255 for (i = 0; i < dch->nkeys; i++)
256 sshkey_free(dch->keys[i]);
257 free(dch->keys);
258 free(dch->key_is_ca);
259 }
260
261 static void
262 free_dest_constraints(struct dest_constraint *dcs, size_t ndcs)
263 {
264 size_t i;
265
266 for (i = 0; i < ndcs; i++) {
267 free_dest_constraint_hop(&dcs[i].from);
268 free_dest_constraint_hop(&dcs[i].to);
269 }
270 free(dcs);
271 }
272
273 #ifdef ENABLE_PKCS11
274 static void
275 dup_dest_constraint_hop(const struct dest_constraint_hop *dch,
276 struct dest_constraint_hop *out)
277 {
278 u_int i;
279 int r;
280
281 out->user = dch->user == NULL ? NULL : xstrdup(dch->user);
282 out->hostname = dch->hostname == NULL ? NULL : xstrdup(dch->hostname);
283 out->is_ca = dch->is_ca;
284 out->nkeys = dch->nkeys;
285 out->keys = out->nkeys == 0 ? NULL :
286 xcalloc(out->nkeys, sizeof(*out->keys));
287 out->key_is_ca = out->nkeys == 0 ? NULL :
288 xcalloc(out->nkeys, sizeof(*out->key_is_ca));
289 for (i = 0; i < dch->nkeys; i++) {
290 if (dch->keys[i] != NULL &&
291 (r = sshkey_from_private(dch->keys[i],
292 &(out->keys[i]))) != 0)
293 fatal_fr(r, "copy key");
294 out->key_is_ca[i] = dch->key_is_ca[i];
295 }
296 }
297
298 static struct dest_constraint *
299 dup_dest_constraints(const struct dest_constraint *dcs, size_t ndcs)
300 {
301 size_t i;
302 struct dest_constraint *ret;
303
304 if (ndcs == 0)
305 return NULL;
306 ret = xcalloc(ndcs, sizeof(*ret));
307 for (i = 0; i < ndcs; i++) {
308 dup_dest_constraint_hop(&dcs[i].from, &ret[i].from);
309 dup_dest_constraint_hop(&dcs[i].to, &ret[i].to);
310 }
311 return ret;
312 }
313 #endif /* ENABLE_PKCS11 */
314
315 #ifdef DEBUG_CONSTRAINTS
316 static void
317 dump_dest_constraint_hop(const struct dest_constraint_hop *dch)
318 {
319 u_int i;
320 char *fp;
321
322 debug_f("user %s hostname %s is_ca %d nkeys %u",
323 dch->user == NULL ? "(null)" : dch->user,
324 dch->hostname == NULL ? "(null)" : dch->hostname,
325 dch->is_ca, dch->nkeys);
326 for (i = 0; i < dch->nkeys; i++) {
327 fp = NULL;
328 if (dch->keys[i] != NULL &&
329 (fp = sshkey_fingerprint(dch->keys[i],
330 SSH_FP_HASH_DEFAULT, SSH_FP_DEFAULT)) == NULL)
331 fatal_f("fingerprint failed");
332 debug_f("key %u/%u: %s%s%s key_is_ca %d", i, dch->nkeys,
333 dch->keys[i] == NULL ? "" : sshkey_ssh_name(dch->keys[i]),
334 dch->keys[i] == NULL ? "" : " ",
335 dch->keys[i] == NULL ? "none" : fp,
336 dch->key_is_ca[i]);
337 free(fp);
338 }
339 }
340 #endif /* DEBUG_CONSTRAINTS */
341
342 static void
343 dump_dest_constraints(const char *context,
344 const struct dest_constraint *dcs, size_t ndcs)
345 {
346 #ifdef DEBUG_CONSTRAINTS
347 size_t i;
348
349 debug_f("%s: %zu constraints", context, ndcs);
350 for (i = 0; i < ndcs; i++) {
351 debug_f("constraint %zu / %zu: from: ", i, ndcs);
352 dump_dest_constraint_hop(&dcs[i].from);
353 debug_f("constraint %zu / %zu: to: ", i, ndcs);
354 dump_dest_constraint_hop(&dcs[i].to);
355 }
356 debug_f("done for %s", context);
357 #endif /* DEBUG_CONSTRAINTS */
358 }
359
360 static void
361 free_identity(Identity *id)
362 {
363 sshkey_free(id->key);
364 free(id->provider);
365 free(id->comment);
366 free(id->sk_provider);
367 free_dest_constraints(id->dest_constraints, id->ndest_constraints);
368 free(id);
369 }
370
371 /*
372 * Match 'key' against the key/CA list in a destination constraint hop
373 * Returns 0 on success or -1 otherwise.
374 */
375 static int
376 match_key_hop(const char *tag, const struct sshkey *key,
377 const struct dest_constraint_hop *dch)
378 {
379 const char *reason = NULL;
380 const char *hostname = dch->hostname ? dch->hostname : "(ORIGIN)";
381 u_int i;
382 char *fp;
383
384 if (key == NULL)
385 return -1;
386 /* XXX logspam */
387 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT,
388 SSH_FP_DEFAULT)) == NULL)
389 fatal_f("fingerprint failed");
390 debug3_f("%s: entering hostname %s, requested key %s %s, %u keys avail",
391 tag, hostname, sshkey_type(key), fp, dch->nkeys);
392 free(fp);
393 for (i = 0; i < dch->nkeys; i++) {
394 if (dch->keys[i] == NULL)
395 return -1;
396 /* XXX logspam */
397 if ((fp = sshkey_fingerprint(dch->keys[i], SSH_FP_HASH_DEFAULT,
398 SSH_FP_DEFAULT)) == NULL)
399 fatal_f("fingerprint failed");
400 debug3_f("%s: key %u: %s%s %s", tag, i,
401 dch->key_is_ca[i] ? "CA " : "",
402 sshkey_type(dch->keys[i]), fp);
403 free(fp);
404 if (!sshkey_is_cert(key)) {
405 /* plain key */
406 if (dch->key_is_ca[i] ||
407 !sshkey_equal(key, dch->keys[i]))
408 continue;
409 return 0;
410 }
411 /* certificate */
412 if (!dch->key_is_ca[i])
413 continue;
414 if (key->cert == NULL || key->cert->signature_key == NULL)
415 return -1; /* shouldn't happen */
416 if (!sshkey_equal(key->cert->signature_key, dch->keys[i]))
417 continue;
418 if (sshkey_cert_check_host(key, hostname, 1,
419 SSH_ALLOWED_CA_SIGALGS, &reason) != 0) {
420 debug_f("cert %s / hostname %s rejected: %s",
421 key->cert->key_id, hostname, reason);
422 continue;
423 }
424 return 0;
425 }
426 return -1;
427 }
428
429 /* Check destination constraints on an identity against the hostkey/user */
430 static int
431 permitted_by_dest_constraints(const struct sshkey *fromkey,
432 const struct sshkey *tokey, Identity *id, const char *user,
433 const char **hostnamep)
434 {
435 size_t i;
436 struct dest_constraint *d;
437
438 if (hostnamep != NULL)
439 *hostnamep = NULL;
440 for (i = 0; i < id->ndest_constraints; i++) {
441 d = id->dest_constraints + i;
442 /* XXX remove logspam */
443 debug2_f("constraint %zu %s%s%s (%u keys) > %s%s%s (%u keys)",
444 i, d->from.user ? d->from.user : "",
445 d->from.user ? "@" : "",
446 d->from.hostname ? d->from.hostname : "(ORIGIN)",
447 d->from.nkeys,
448 d->to.user ? d->to.user : "", d->to.user ? "@" : "",
449 d->to.hostname ? d->to.hostname : "(ANY)", d->to.nkeys);
450
451 /* Match 'from' key */
452 if (fromkey == NULL) {
453 /* We are matching the first hop */
454 if (d->from.hostname != NULL || d->from.nkeys != 0)
455 continue;
456 } else if (match_key_hop("from", fromkey, &d->from) != 0)
457 continue;
458
459 /* Match 'to' key */
460 if (tokey != NULL && match_key_hop("to", tokey, &d->to) != 0)
461 continue;
462
463 /* Match user if specified */
464 if (d->to.user != NULL && user != NULL &&
465 !match_pattern(user, d->to.user))
466 continue;
467
468 /* successfully matched this constraint */
469 if (hostnamep != NULL)
470 *hostnamep = d->to.hostname;
471 debug2_f("allowed for hostname %s",
472 d->to.hostname == NULL ? "*" : d->to.hostname);
473 return 0;
474 }
475 /* no match */
476 debug2_f("%s identity \"%s\" not permitted for this destination",
477 sshkey_type(id->key), id->comment);
478 return -1;
479 }
480
481 /*
482 * Check whether hostkeys on a SocketEntry and the optionally specified user
483 * are permitted by the destination constraints on the Identity.
484 * Returns 0 on success or -1 otherwise.
485 */
486 static int
487 identity_permitted(Identity *id, SocketEntry *e, char *user,
488 const char **forward_hostnamep, const char **last_hostnamep)
489 {
490 size_t i;
491 const char **hp;
492 struct hostkey_sid *hks;
493 const struct sshkey *fromkey = NULL;
494 const char *test_user;
495 char *fp1, *fp2;
496
497 /* XXX remove logspam */
498 debug3_f("entering: key %s comment \"%s\", %zu socket bindings, "
499 "%zu constraints", sshkey_type(id->key), id->comment,
500 e->nsession_ids, id->ndest_constraints);
501 if (id->ndest_constraints == 0)
502 return 0; /* unconstrained */
503 if (e->session_bind_attempted && e->nsession_ids == 0) {
504 error_f("previous session bind failed on socket");
505 return -1;
506 }
507 if (e->nsession_ids == 0)
508 return 0; /* local use */
509 /*
510 * Walk through the hops recorded by session_id and try to find a
511 * constraint that satisfies each.
512 */
513 for (i = 0; i < e->nsession_ids; i++) {
514 hks = e->session_ids + i;
515 if (hks->key == NULL)
516 fatal_f("internal error: no bound key");
517 /* XXX remove logspam */
518 fp1 = fp2 = NULL;
519 if (fromkey != NULL &&
520 (fp1 = sshkey_fingerprint(fromkey, SSH_FP_HASH_DEFAULT,
521 SSH_FP_DEFAULT)) == NULL)
522 fatal_f("fingerprint failed");
523 if ((fp2 = sshkey_fingerprint(hks->key, SSH_FP_HASH_DEFAULT,
524 SSH_FP_DEFAULT)) == NULL)
525 fatal_f("fingerprint failed");
526 debug3_f("socketentry fd=%d, entry %zu %s, "
527 "from hostkey %s %s to user %s hostkey %s %s",
528 e->fd, i, hks->forwarded ? "FORWARD" : "AUTH",
529 fromkey ? sshkey_type(fromkey) : "(ORIGIN)",
530 fromkey ? fp1 : "", user ? user : "(ANY)",
531 sshkey_type(hks->key), fp2);
532 free(fp1);
533 free(fp2);
534 /*
535 * Record the hostnames for the initial forwarding and
536 * the final destination.
537 */
538 hp = NULL;
539 if (i == e->nsession_ids - 1)
540 hp = last_hostnamep;
541 else if (i == 0)
542 hp = forward_hostnamep;
543 /* Special handling for final recorded binding */
544 test_user = NULL;
545 if (i == e->nsession_ids - 1) {
546 /* Can only check user at final hop */
547 test_user = user;
548 /*
549 * user is only presented for signature requests.
550 * If this is the case, make sure last binding is not
551 * for a forwarding.
552 */
553 if (hks->forwarded && user != NULL) {
554 error_f("tried to sign on forwarding hop");
555 return -1;
556 }
557 } else if (!hks->forwarded) {
558 error_f("tried to forward though signing bind");
559 return -1;
560 }
561 if (permitted_by_dest_constraints(fromkey, hks->key, id,
562 test_user, hp) != 0)
563 return -1;
564 fromkey = hks->key;
565 }
566 /*
567 * Another special case: if the last bound session ID was for a
568 * forwarding, and this function is not being called to check a sign
569 * request (i.e. no 'user' supplied), then only permit the key if
570 * there is a permission that would allow it to be used at another
571 * destination. This hides keys that are allowed to be used to
572 * authenticate *to* a host but not permitted for *use* beyond it.
573 */
574 hks = &e->session_ids[e->nsession_ids - 1];
575 if (hks->forwarded && user == NULL &&
576 permitted_by_dest_constraints(hks->key, NULL, id,
577 NULL, NULL) != 0) {
578 debug3_f("key permitted at host but not after");
579 return -1;
580 }
581
582 /* success */
583 return 0;
584 }
585
586 static int
587 socket_is_remote(SocketEntry *e)
588 {
589 return e->session_bind_attempted || (e->nsession_ids != 0);
590 }
591
592 /* return matching private key for given public key */
593 static Identity *
594 lookup_identity(struct sshkey *key)
595 {
596 Identity *id;
597
598 TAILQ_FOREACH(id, &idtab->idlist, next) {
599 if (sshkey_equal(key, id->key))
600 return (id);
601 }
602 return (NULL);
603 }
604
605 /* Check confirmation of keysign request */
606 static int
607 confirm_key(Identity *id, const char *extra)
608 {
609 char *p;
610 int ret = -1;
611
612 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT);
613 if (p != NULL &&
614 ask_permission("Allow use of key %s?\nKey fingerprint %s.%s%s",
615 id->comment, p,
616 extra == NULL ? "" : "\n", extra == NULL ? "" : extra))
617 ret = 0;
618 free(p);
619
620 return (ret);
621 }
622
623 static void
624 send_status(SocketEntry *e, int success)
625 {
626 int r;
627
628 if ((r = sshbuf_put_u32(e->output, 1)) != 0 ||
629 (r = sshbuf_put_u8(e->output, success ?
630 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0)
631 fatal_fr(r, "compose");
632 }
633
634 /* send list of supported public keys to 'client' */
635 static void
636 process_request_identities(SocketEntry *e)
637 {
638 Identity *id;
639 struct sshbuf *msg, *keys;
640 int r;
641 u_int i = 0, nentries = 0;
642 char *fp;
643
644 debug2_f("entering");
645
646 if ((msg = sshbuf_new()) == NULL || (keys = sshbuf_new()) == NULL)
647 fatal_f("sshbuf_new failed");
648 TAILQ_FOREACH(id, &idtab->idlist, next) {
649 if ((fp = sshkey_fingerprint(id->key, SSH_FP_HASH_DEFAULT,
650 SSH_FP_DEFAULT)) == NULL)
651 fatal_f("fingerprint failed");
652 debug_f("key %u / %u: %s %s", i++, idtab->nentries,
653 sshkey_ssh_name(id->key), fp);
654 dump_dest_constraints(__func__,
655 id->dest_constraints, id->ndest_constraints);
656 free(fp);
657 /* identity not visible, don't include in response */
658 if (identity_permitted(id, e, NULL, NULL, NULL) != 0)
659 continue;
660 if ((r = sshkey_puts_opts(id->key, keys,
661 SSHKEY_SERIALIZE_INFO)) != 0 ||
662 (r = sshbuf_put_cstring(keys, id->comment)) != 0) {
663 error_fr(r, "compose key/comment");
664 continue;
665 }
666 nentries++;
667 }
668 debug2_f("replying with %u allowed of %u available keys",
669 nentries, idtab->nentries);
670 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
671 (r = sshbuf_put_u32(msg, nentries)) != 0 ||
672 (r = sshbuf_putb(msg, keys)) != 0)
673 fatal_fr(r, "compose");
674 if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
675 fatal_fr(r, "enqueue");
676 sshbuf_free(msg);
677 sshbuf_free(keys);
678 }
679
680
681 static char *
682 agent_decode_alg(struct sshkey *key, u_int flags)
683 {
684 if (key->type == KEY_RSA) {
685 if (flags & SSH_AGENT_RSA_SHA2_256)
686 return "rsa-sha2-256";
687 else if (flags & SSH_AGENT_RSA_SHA2_512)
688 return "rsa-sha2-512";
689 } else if (key->type == KEY_RSA_CERT) {
690 if (flags & SSH_AGENT_RSA_SHA2_256)
691 return "rsa-sha2-256-cert-v01@openssh.com";
692 else if (flags & SSH_AGENT_RSA_SHA2_512)
693 return "rsa-sha2-512-cert-v01@openssh.com";
694 }
695 return NULL;
696 }
697
698 /*
699 * Attempt to parse the contents of a buffer as a SSH publickey userauth
700 * request, checking its contents for consistency and matching the embedded
701 * key against the one that is being used for signing.
702 * Note: does not modify msg buffer.
703 * Optionally extract the username, session ID and/or hostkey from the request.
704 */
705 static int
706 parse_userauth_request(struct sshbuf *msg, const struct sshkey *expected_key,
707 char **userp, struct sshbuf **sess_idp, struct sshkey **hostkeyp)
708 {
709 struct sshbuf *b = NULL, *sess_id = NULL;
710 char *user = NULL, *service = NULL, *method = NULL, *pkalg = NULL;
711 int r;
712 u_char t, sig_follows;
713 struct sshkey *mkey = NULL, *hostkey = NULL;
714
715 if (userp != NULL)
716 *userp = NULL;
717 if (sess_idp != NULL)
718 *sess_idp = NULL;
719 if (hostkeyp != NULL)
720 *hostkeyp = NULL;
721 if ((b = sshbuf_fromb(msg)) == NULL)
722 fatal_f("sshbuf_fromb");
723
724 /* SSH userauth request */
725 if ((r = sshbuf_froms(b, &sess_id)) != 0)
726 goto out;
727 if (sshbuf_len(sess_id) == 0) {
728 r = SSH_ERR_INVALID_FORMAT;
729 goto out;
730 }
731 if ((r = sshbuf_get_u8(b, &t)) != 0 || /* SSH2_MSG_USERAUTH_REQUEST */
732 (r = sshbuf_get_cstring(b, &user, NULL)) != 0 || /* server user */
733 (r = sshbuf_get_cstring(b, &service, NULL)) != 0 || /* service */
734 (r = sshbuf_get_cstring(b, &method, NULL)) != 0 || /* method */
735 (r = sshbuf_get_u8(b, &sig_follows)) != 0 || /* sig-follows */
736 (r = sshbuf_get_cstring(b, &pkalg, NULL)) != 0 || /* alg */
737 (r = sshkey_froms(b, &mkey)) != 0) /* key */
738 goto out;
739 if (t != SSH2_MSG_USERAUTH_REQUEST ||
740 sig_follows != 1 ||
741 strcmp(service, "ssh-connection") != 0 ||
742 !sshkey_equal(expected_key, mkey) ||
743 sshkey_type_from_name(pkalg) != expected_key->type) {
744 r = SSH_ERR_INVALID_FORMAT;
745 goto out;
746 }
747 if (strcmp(method, "publickey-hostbound-v00@openssh.com") == 0) {
748 if ((r = sshkey_froms(b, &hostkey)) != 0)
749 goto out;
750 } else if (strcmp(method, "publickey") != 0) {
751 r = SSH_ERR_INVALID_FORMAT;
752 goto out;
753 }
754 if (sshbuf_len(b) != 0) {
755 r = SSH_ERR_INVALID_FORMAT;
756 goto out;
757 }
758 /* success */
759 r = 0;
760 debug3_f("well formed userauth");
761 if (userp != NULL) {
762 *userp = user;
763 user = NULL;
764 }
765 if (sess_idp != NULL) {
766 *sess_idp = sess_id;
767 sess_id = NULL;
768 }
769 if (hostkeyp != NULL) {
770 *hostkeyp = hostkey;
771 hostkey = NULL;
772 }
773 out:
774 sshbuf_free(b);
775 sshbuf_free(sess_id);
776 free(user);
777 free(service);
778 free(method);
779 free(pkalg);
780 sshkey_free(mkey);
781 sshkey_free(hostkey);
782 return r;
783 }
784
785 /*
786 * Attempt to parse the contents of a buffer as a SSHSIG signature request.
787 * Note: does not modify buffer.
788 */
789 static int
790 parse_sshsig_request(struct sshbuf *msg)
791 {
792 int r;
793 struct sshbuf *b;
794
795 if ((b = sshbuf_fromb(msg)) == NULL)
796 fatal_f("sshbuf_fromb");
797
798 if ((r = sshbuf_cmp(b, 0, "SSHSIG", 6)) != 0 ||
799 (r = sshbuf_consume(b, 6)) != 0 ||
800 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* namespace */
801 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0 || /* reserved */
802 (r = sshbuf_get_cstring(b, NULL, NULL)) != 0 || /* hashalg */
803 (r = sshbuf_get_string_direct(b, NULL, NULL)) != 0) /* H(msg) */
804 goto out;
805 if (sshbuf_len(b) != 0) {
806 r = SSH_ERR_INVALID_FORMAT;
807 goto out;
808 }
809 /* success */
810 r = 0;
811 out:
812 sshbuf_free(b);
813 return r;
814 }
815
816 /*
817 * This function inspects a message to be signed by a FIDO key that has a
818 * web-like application string (i.e. one that does not begin with "ssh:".
819 * It checks that the message is one of those expected for SSH operations
820 * (pubkey userauth, sshsig, CA key signing) to exclude signing challenges
821 * for the web.
822 */
823 static int
824 check_websafe_message_contents(struct sshkey *key, struct sshbuf *data)
825 {
826 if (parse_userauth_request(data, key, NULL, NULL, NULL) == 0) {
827 debug_f("signed data matches public key userauth request");
828 return 1;
829 }
830 if (parse_sshsig_request(data) == 0) {
831 debug_f("signed data matches SSHSIG signature request");
832 return 1;
833 }
834
835 /* XXX check CA signature operation */
836
837 error("web-origin key attempting to sign non-SSH message");
838 return 0;
839 }
840
841 static int
842 buf_equal(const struct sshbuf *a, const struct sshbuf *b)
843 {
844 if (sshbuf_ptr(a) == NULL || sshbuf_ptr(b) == NULL)
845 return SSH_ERR_INVALID_ARGUMENT;
846 if (sshbuf_len(a) != sshbuf_len(b))
847 return SSH_ERR_INVALID_FORMAT;
848 if (timingsafe_bcmp(sshbuf_ptr(a), sshbuf_ptr(b), sshbuf_len(a)) != 0)
849 return SSH_ERR_INVALID_FORMAT;
850 return 0;
851 }
852
853 /* ssh2 only */
854 static void
855 process_sign_request2(SocketEntry *e)
856 {
857 u_char *signature = NULL;
858 size_t slen = 0;
859 u_int compat = 0, flags;
860 int r, ok = -1, retried = 0;
861 char *fp = NULL, *pin = NULL, *prompt = NULL;
862 char *user = NULL, *sig_dest = NULL;
863 const char *fwd_host = NULL, *dest_host = NULL;
864 struct sshbuf *msg = NULL, *data = NULL, *sid = NULL;
865 struct sshkey *key = NULL, *hostkey = NULL;
866 struct identity *id;
867 struct notifier_ctx *notifier = NULL;
868
869 debug_f("entering");
870
871 if ((msg = sshbuf_new()) == NULL || (data = sshbuf_new()) == NULL)
872 fatal_f("sshbuf_new failed");
873 if ((r = sshkey_froms(e->request, &key)) != 0 ||
874 (r = sshbuf_get_stringb(e->request, data)) != 0 ||
875 (r = sshbuf_get_u32(e->request, &flags)) != 0) {
876 error_fr(r, "parse");
877 goto send;
878 }
879
880 if ((id = lookup_identity(key)) == NULL) {
881 verbose_f("%s key not found", sshkey_type(key));
882 goto send;
883 }
884 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT,
885 SSH_FP_DEFAULT)) == NULL)
886 fatal_f("fingerprint failed");
887
888 if (id->ndest_constraints != 0) {
889 if (e->nsession_ids == 0) {
890 logit_f("refusing use of destination-constrained key "
891 "to sign on unbound connection");
892 goto send;
893 }
894 if (parse_userauth_request(data, key, &user, &sid,
895 &hostkey) != 0) {
896 logit_f("refusing use of destination-constrained key "
897 "to sign an unidentified signature");
898 goto send;
899 }
900 /* XXX logspam */
901 debug_f("user=%s", user);
902 if (identity_permitted(id, e, user, &fwd_host, &dest_host) != 0)
903 goto send;
904 /* XXX display fwd_host/dest_host in askpass UI */
905 /*
906 * Ensure that the session ID is the most recent one
907 * registered on the socket - it should have been bound by
908 * ssh immediately before userauth.
909 */
910 if (buf_equal(sid,
911 e->session_ids[e->nsession_ids - 1].sid) != 0) {
912 error_f("unexpected session ID (%zu listed) on "
913 "signature request for target user %s with "
914 "key %s %s", e->nsession_ids, user,
915 sshkey_type(id->key), fp);
916 goto send;
917 }
918 /*
919 * Ensure that the hostkey embedded in the signature matches
920 * the one most recently bound to the socket. An exception is
921 * made for the initial forwarding hop.
922 */
923 if (e->nsession_ids > 1 && hostkey == NULL) {
924 error_f("refusing use of destination-constrained key: "
925 "no hostkey recorded in signature for forwarded "
926 "connection");
927 goto send;
928 }
929 if (hostkey != NULL && !sshkey_equal(hostkey,
930 e->session_ids[e->nsession_ids - 1].key)) {
931 error_f("refusing use of destination-constrained key: "
932 "mismatch between hostkey in request and most "
933 "recently bound session");
934 goto send;
935 }
936 xasprintf(&sig_dest, "public key authentication request for "
937 "user \"%s\" to listed host", user);
938 }
939 if (id->confirm && confirm_key(id, sig_dest) != 0) {
940 verbose_f("user refused key");
941 goto send;
942 }
943 if (sshkey_is_sk(id->key)) {
944 if (restrict_websafe &&
945 strncmp(id->key->sk_application, "ssh:", 4) != 0 &&
946 !check_websafe_message_contents(key, data)) {
947 /* error already logged */
948 goto send;
949 }
950 if (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) {
951 notifier = notify_start(0,
952 "Confirm user presence for key %s %s%s%s",
953 sshkey_type(id->key), fp,
954 sig_dest == NULL ? "" : "\n",
955 sig_dest == NULL ? "" : sig_dest);
956 }
957 }
958 retry_pin:
959 if ((r = sshkey_sign(id->key, &signature, &slen,
960 sshbuf_ptr(data), sshbuf_len(data), agent_decode_alg(key, flags),
961 id->sk_provider, pin, compat)) != 0) {
962 debug_fr(r, "sshkey_sign");
963 if (pin == NULL && !retried && sshkey_is_sk(id->key) &&
964 r == SSH_ERR_KEY_WRONG_PASSPHRASE) {
965 notify_complete(notifier, NULL);
966 notifier = NULL;
967 /* XXX include sig_dest */
968 xasprintf(&prompt, "Enter PIN%sfor %s key %s: ",
969 (id->key->sk_flags & SSH_SK_USER_PRESENCE_REQD) ?
970 " and confirm user presence " : " ",
971 sshkey_type(id->key), fp);
972 pin = read_passphrase(prompt, RP_USE_ASKPASS);
973 retried = 1;
974 goto retry_pin;
975 }
976 error_fr(r, "sshkey_sign");
977 goto send;
978 }
979 /* Success */
980 ok = 0;
981 debug_f("good signature");
982 send:
983 notify_complete(notifier, "User presence confirmed");
984
985 if (ok == 0) {
986 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 ||
987 (r = sshbuf_put_string(msg, signature, slen)) != 0)
988 fatal_fr(r, "compose");
989 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
990 fatal_fr(r, "compose failure");
991
992 if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
993 fatal_fr(r, "enqueue");
994
995 sshbuf_free(sid);
996 sshbuf_free(data);
997 sshbuf_free(msg);
998 sshkey_free(key);
999 sshkey_free(hostkey);
1000 free(fp);
1001 free(signature);
1002 free(sig_dest);
1003 free(user);
1004 free(prompt);
1005 if (pin != NULL)
1006 freezero(pin, strlen(pin));
1007 }
1008
1009 /* shared */
1010 static void
1011 process_remove_identity(SocketEntry *e)
1012 {
1013 int r, success = 0;
1014 struct sshkey *key = NULL;
1015 Identity *id;
1016
1017 debug2_f("entering");
1018 if ((r = sshkey_froms(e->request, &key)) != 0) {
1019 error_fr(r, "parse key");
1020 goto done;
1021 }
1022 if ((id = lookup_identity(key)) == NULL) {
1023 debug_f("key not found");
1024 goto done;
1025 }
1026 /* identity not visible, cannot be removed */
1027 if (identity_permitted(id, e, NULL, NULL, NULL) != 0)
1028 goto done; /* error already logged */
1029 /* We have this key, free it. */
1030 if (idtab->nentries < 1)
1031 fatal_f("internal error: nentries %d", idtab->nentries);
1032 TAILQ_REMOVE(&idtab->idlist, id, next);
1033 free_identity(id);
1034 idtab->nentries--;
1035 success = 1;
1036 done:
1037 sshkey_free(key);
1038 send_status(e, success);
1039 }
1040
1041 static void
1042 process_remove_all_identities(SocketEntry *e)
1043 {
1044 Identity *id;
1045
1046 debug2_f("entering");
1047 /* Loop over all identities and clear the keys. */
1048 for (id = TAILQ_FIRST(&idtab->idlist); id;
1049 id = TAILQ_FIRST(&idtab->idlist)) {
1050 TAILQ_REMOVE(&idtab->idlist, id, next);
1051 free_identity(id);
1052 }
1053
1054 /* Mark that there are no identities. */
1055 idtab->nentries = 0;
1056
1057 /* Send success. */
1058 send_status(e, 1);
1059 }
1060
1061 /* removes expired keys and returns number of seconds until the next expiry */
1062 static time_t
1063 reaper(void)
1064 {
1065 time_t deadline = 0, now = monotime();
1066 Identity *id, *nxt;
1067
1068 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) {
1069 nxt = TAILQ_NEXT(id, next);
1070 if (id->death == 0)
1071 continue;
1072 if (now >= id->death) {
1073 debug("expiring key '%s'", id->comment);
1074 TAILQ_REMOVE(&idtab->idlist, id, next);
1075 free_identity(id);
1076 idtab->nentries--;
1077 } else
1078 deadline = (deadline == 0) ? id->death :
1079 MINIMUM(deadline, id->death);
1080 }
1081 if (deadline == 0 || deadline <= now)
1082 return 0;
1083 else
1084 return (deadline - now);
1085 }
1086
1087 static int
1088 parse_dest_constraint_hop(struct sshbuf *b, struct dest_constraint_hop *dch)
1089 {
1090 u_char key_is_ca;
1091 size_t elen = 0;
1092 int r;
1093 struct sshkey *k = NULL;
1094 char *fp;
1095
1096 memset(dch, '\0', sizeof(*dch));
1097 if ((r = sshbuf_get_cstring(b, &dch->user, NULL)) != 0 ||
1098 (r = sshbuf_get_cstring(b, &dch->hostname, NULL)) != 0 ||
1099 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) {
1100 error_fr(r, "parse");
1101 goto out;
1102 }
1103 if (elen != 0) {
1104 error_f("unsupported extensions (len %zu)", elen);
1105 r = SSH_ERR_FEATURE_UNSUPPORTED;
1106 goto out;
1107 }
1108 if (*dch->hostname == '\0') {
1109 free(dch->hostname);
1110 dch->hostname = NULL;
1111 }
1112 if (*dch->user == '\0') {
1113 free(dch->user);
1114 dch->user = NULL;
1115 }
1116 while (sshbuf_len(b) != 0) {
1117 dch->keys = xrecallocarray(dch->keys, dch->nkeys,
1118 dch->nkeys + 1, sizeof(*dch->keys));
1119 dch->key_is_ca = xrecallocarray(dch->key_is_ca, dch->nkeys,
1120 dch->nkeys + 1, sizeof(*dch->key_is_ca));
1121 if ((r = sshkey_froms(b, &k)) != 0 ||
1122 (r = sshbuf_get_u8(b, &key_is_ca)) != 0)
1123 goto out;
1124 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT,
1125 SSH_FP_DEFAULT)) == NULL)
1126 fatal_f("fingerprint failed");
1127 debug3_f("%s%s%s: adding %skey %s %s",
1128 dch->user == NULL ? "" : dch->user,
1129 dch->user == NULL ? "" : "@",
1130 dch->hostname, key_is_ca ? "CA " : "", sshkey_type(k), fp);
1131 free(fp);
1132 dch->keys[dch->nkeys] = k;
1133 dch->key_is_ca[dch->nkeys] = key_is_ca != 0;
1134 dch->nkeys++;
1135 k = NULL; /* transferred */
1136 }
1137 /* success */
1138 r = 0;
1139 out:
1140 sshkey_free(k);
1141 return r;
1142 }
1143
1144 static int
1145 parse_dest_constraint(struct sshbuf *m, struct dest_constraint *dc)
1146 {
1147 struct sshbuf *b = NULL, *frombuf = NULL, *tobuf = NULL;
1148 int r;
1149 size_t elen = 0;
1150
1151 debug3_f("entering");
1152
1153 memset(dc, '\0', sizeof(*dc));
1154 if ((r = sshbuf_froms(m, &b)) != 0 ||
1155 (r = sshbuf_froms(b, &frombuf)) != 0 ||
1156 (r = sshbuf_froms(b, &tobuf)) != 0 ||
1157 (r = sshbuf_get_string_direct(b, NULL, &elen)) != 0) {
1158 error_fr(r, "parse");
1159 goto out;
1160 }
1161 if ((r = parse_dest_constraint_hop(frombuf, &dc->from)) != 0 ||
1162 (r = parse_dest_constraint_hop(tobuf, &dc->to)) != 0)
1163 goto out; /* already logged */
1164 if (elen != 0) {
1165 error_f("unsupported extensions (len %zu)", elen);
1166 r = SSH_ERR_FEATURE_UNSUPPORTED;
1167 goto out;
1168 }
1169 debug2_f("parsed %s (%u keys) > %s%s%s (%u keys)",
1170 dc->from.hostname ? dc->from.hostname : "(ORIGIN)", dc->from.nkeys,
1171 dc->to.user ? dc->to.user : "", dc->to.user ? "@" : "",
1172 dc->to.hostname ? dc->to.hostname : "(ANY)", dc->to.nkeys);
1173 /* check consistency */
1174 if ((dc->from.hostname == NULL) != (dc->from.nkeys == 0) ||
1175 dc->from.user != NULL) {
1176 error_f("inconsistent \"from\" specification");
1177 r = SSH_ERR_INVALID_FORMAT;
1178 goto out;
1179 }
1180 if (dc->to.hostname == NULL || dc->to.nkeys == 0) {
1181 error_f("incomplete \"to\" specification");
1182 r = SSH_ERR_INVALID_FORMAT;
1183 goto out;
1184 }
1185 /* success */
1186 r = 0;
1187 out:
1188 sshbuf_free(b);
1189 sshbuf_free(frombuf);
1190 sshbuf_free(tobuf);
1191 return r;
1192 }
1193
1194 static int
1195 parse_key_constraint_extension(struct sshbuf *m, char **sk_providerp,
1196 struct dest_constraint **dcsp, size_t *ndcsp, int *cert_onlyp,
1197 struct sshkey ***certs, size_t *ncerts)
1198 {
1199 char *ext_name = NULL;
1200 int r;
1201 struct sshbuf *b = NULL;
1202 u_char v;
1203 struct sshkey *k;
1204
1205 if ((r = sshbuf_get_cstring(m, &ext_name, NULL)) != 0) {
1206 error_fr(r, "parse constraint extension");
1207 goto out;
1208 }
1209 debug_f("constraint ext %s", ext_name);
1210 if (strcmp(ext_name, "sk-provider@openssh.com") == 0) {
1211 if (sk_providerp == NULL) {
1212 error_f("%s not valid here", ext_name);
1213 r = SSH_ERR_INVALID_FORMAT;
1214 goto out;
1215 }
1216 if (*sk_providerp != NULL) {
1217 error_f("%s already set", ext_name);
1218 r = SSH_ERR_INVALID_FORMAT;
1219 goto out;
1220 }
1221 if ((r = sshbuf_get_cstring(m, sk_providerp, NULL)) != 0) {
1222 error_fr(r, "parse %s", ext_name);
1223 goto out;
1224 }
1225 } else if (strcmp(ext_name,
1226 "restrict-destination-v00@openssh.com") == 0) {
1227 if (*dcsp != NULL) {
1228 error_f("%s already set", ext_name);
1229 goto out;
1230 }
1231 if ((r = sshbuf_froms(m, &b)) != 0) {
1232 error_fr(r, "parse %s outer", ext_name);
1233 goto out;
1234 }
1235 while (sshbuf_len(b) != 0) {
1236 if (*ndcsp >= AGENT_MAX_DEST_CONSTRAINTS) {
1237 error_f("too many %s constraints", ext_name);
1238 goto out;
1239 }
1240 *dcsp = xrecallocarray(*dcsp, *ndcsp, *ndcsp + 1,
1241 sizeof(**dcsp));
1242 if ((r = parse_dest_constraint(b,
1243 *dcsp + (*ndcsp)++)) != 0)
1244 goto out; /* error already logged */
1245 }
1246 } else if (strcmp(ext_name,
1247 "associated-certs-v00@openssh.com") == 0) {
1248 if (certs == NULL || ncerts == NULL || cert_onlyp == NULL) {
1249 error_f("%s not valid here", ext_name);
1250 r = SSH_ERR_INVALID_FORMAT;
1251 goto out;
1252 }
1253 if (*certs != NULL) {
1254 error_f("%s already set", ext_name);
1255 goto out;
1256 }
1257 if ((r = sshbuf_get_u8(m, &v)) != 0 ||
1258 (r = sshbuf_froms(m, &b)) != 0) {
1259 error_fr(r, "parse %s", ext_name);
1260 goto out;
1261 }
1262 *cert_onlyp = v != 0;
1263 while (sshbuf_len(b) != 0) {
1264 if (*ncerts >= AGENT_MAX_EXT_CERTS) {
1265 error_f("too many %s constraints", ext_name);
1266 goto out;
1267 }
1268 *certs = xrecallocarray(*certs, *ncerts, *ncerts + 1,
1269 sizeof(**certs));
1270 if ((r = sshkey_froms(b, &k)) != 0) {
1271 error_fr(r, "parse key");
1272 goto out;
1273 }
1274 (*certs)[(*ncerts)++] = k;
1275 }
1276 } else {
1277 error_f("unsupported constraint \"%s\"", ext_name);
1278 r = SSH_ERR_FEATURE_UNSUPPORTED;
1279 goto out;
1280 }
1281 /* success */
1282 r = 0;
1283 out:
1284 free(ext_name);
1285 sshbuf_free(b);
1286 return r;
1287 }
1288
1289 static int
1290 parse_key_constraints(struct sshbuf *m, struct sshkey *k, time_t *deathp,
1291 u_int *secondsp, int *confirmp, char **sk_providerp,
1292 struct dest_constraint **dcsp, size_t *ndcsp,
1293 int *cert_onlyp, size_t *ncerts, struct sshkey ***certs)
1294 {
1295 u_char ctype;
1296 int r;
1297 u_int seconds, maxsign = 0;
1298
1299 while (sshbuf_len(m)) {
1300 if ((r = sshbuf_get_u8(m, &ctype)) != 0) {
1301 error_fr(r, "parse constraint type");
1302 goto out;
1303 }
1304 switch (ctype) {
1305 case SSH_AGENT_CONSTRAIN_LIFETIME:
1306 if (*deathp != 0) {
1307 error_f("lifetime already set");
1308 r = SSH_ERR_INVALID_FORMAT;
1309 goto out;
1310 }
1311 if ((r = sshbuf_get_u32(m, &seconds)) != 0) {
1312 error_fr(r, "parse lifetime constraint");
1313 goto out;
1314 }
1315 *deathp = monotime() + seconds;
1316 *secondsp = seconds;
1317 break;
1318 case SSH_AGENT_CONSTRAIN_CONFIRM:
1319 if (*confirmp != 0) {
1320 error_f("confirm already set");
1321 r = SSH_ERR_INVALID_FORMAT;
1322 goto out;
1323 }
1324 *confirmp = 1;
1325 break;
1326 case SSH_AGENT_CONSTRAIN_MAXSIGN:
1327 if (k == NULL) {
1328 error_f("maxsign not valid here");
1329 r = SSH_ERR_INVALID_FORMAT;
1330 goto out;
1331 }
1332 if (maxsign != 0) {
1333 error_f("maxsign already set");
1334 r = SSH_ERR_INVALID_FORMAT;
1335 goto out;
1336 }
1337 if ((r = sshbuf_get_u32(m, &maxsign)) != 0) {
1338 error_fr(r, "parse maxsign constraint");
1339 goto out;
1340 }
1341 if ((r = sshkey_enable_maxsign(k, maxsign)) != 0) {
1342 error_fr(r, "enable maxsign");
1343 goto out;
1344 }
1345 break;
1346 case SSH_AGENT_CONSTRAIN_EXTENSION:
1347 if ((r = parse_key_constraint_extension(m,
1348 sk_providerp, dcsp, ndcsp,
1349 cert_onlyp, certs, ncerts)) != 0)
1350 goto out; /* error already logged */
1351 break;
1352 default:
1353 error_f("Unknown constraint %d", ctype);
1354 r = SSH_ERR_FEATURE_UNSUPPORTED;
1355 goto out;
1356 }
1357 }
1358 /* success */
1359 r = 0;
1360 out:
1361 return r;
1362 }
1363
1364 static void
1365 process_add_identity(SocketEntry *e)
1366 {
1367 Identity *id;
1368 int success = 0, confirm = 0;
1369 char *fp, *comment = NULL, *sk_provider = NULL;
1370 char canonical_provider[PATH_MAX];
1371 time_t death = 0;
1372 u_int seconds = 0;
1373 struct dest_constraint *dest_constraints = NULL;
1374 size_t ndest_constraints = 0;
1375 struct sshkey *k = NULL;
1376 int r = SSH_ERR_INTERNAL_ERROR;
1377
1378 debug2_f("entering");
1379 if ((r = sshkey_private_deserialize(e->request, &k)) != 0 ||
1380 k == NULL ||
1381 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) {
1382 error_fr(r, "parse");
1383 goto out;
1384 }
1385 if (parse_key_constraints(e->request, k, &death, &seconds, &confirm,
1386 &sk_provider, &dest_constraints, &ndest_constraints,
1387 NULL, NULL, NULL) != 0) {
1388 error_f("failed to parse constraints");
1389 sshbuf_reset(e->request);
1390 goto out;
1391 }
1392 dump_dest_constraints(__func__, dest_constraints, ndest_constraints);
1393
1394 if (sk_provider != NULL) {
1395 if (!sshkey_is_sk(k)) {
1396 error("Cannot add provider: %s is not an "
1397 "authenticator-hosted key", sshkey_type(k));
1398 goto out;
1399 }
1400 if (strcasecmp(sk_provider, "internal") == 0) {
1401 debug_f("internal provider");
1402 } else {
1403 if (socket_is_remote(e) && !remote_add_provider) {
1404 verbose("failed add of SK provider \"%.100s\": "
1405 "remote addition of providers is disabled",
1406 sk_provider);
1407 goto out;
1408 }
1409 if (realpath(sk_provider, canonical_provider) == NULL) {
1410 verbose("failed provider \"%.100s\": "
1411 "realpath: %s", sk_provider,
1412 strerror(errno));
1413 goto out;
1414 }
1415 free(sk_provider);
1416 sk_provider = xstrdup(canonical_provider);
1417 if (match_pattern_list(sk_provider,
1418 allowed_providers, 0) != 1) {
1419 error("Refusing add key: "
1420 "provider %s not allowed", sk_provider);
1421 goto out;
1422 }
1423 }
1424 }
1425 if ((r = sshkey_shield_private(k)) != 0) {
1426 error_fr(r, "shield private");
1427 goto out;
1428 }
1429 if (lifetime && !death)
1430 death = monotime() + lifetime;
1431 if ((id = lookup_identity(k)) == NULL) {
1432 id = xcalloc(1, sizeof(Identity));
1433 TAILQ_INSERT_TAIL(&idtab->idlist, id, next);
1434 /* Increment the number of identities. */
1435 idtab->nentries++;
1436 } else {
1437 /* identity not visible, do not update */
1438 if (identity_permitted(id, e, NULL, NULL, NULL) != 0)
1439 goto out; /* error already logged */
1440 /* key state might have been updated */
1441 sshkey_free(id->key);
1442 free(id->comment);
1443 free(id->sk_provider);
1444 free_dest_constraints(id->dest_constraints,
1445 id->ndest_constraints);
1446 }
1447 /* success */
1448 id->key = k;
1449 id->comment = comment;
1450 id->death = death;
1451 id->confirm = confirm;
1452 id->sk_provider = sk_provider;
1453 id->dest_constraints = dest_constraints;
1454 id->ndest_constraints = ndest_constraints;
1455
1456 if ((fp = sshkey_fingerprint(k, SSH_FP_HASH_DEFAULT,
1457 SSH_FP_DEFAULT)) == NULL)
1458 fatal_f("sshkey_fingerprint failed");
1459 debug_f("add %s %s \"%.100s\" (life: %u) (confirm: %u) "
1460 "(provider: %s) (destination constraints: %zu)",
1461 sshkey_ssh_name(k), fp, comment, seconds, confirm,
1462 sk_provider == NULL ? "none" : sk_provider, ndest_constraints);
1463 free(fp);
1464 /* transferred */
1465 k = NULL;
1466 comment = NULL;
1467 sk_provider = NULL;
1468 dest_constraints = NULL;
1469 ndest_constraints = 0;
1470 success = 1;
1471 out:
1472 free(sk_provider);
1473 free(comment);
1474 sshkey_free(k);
1475 free_dest_constraints(dest_constraints, ndest_constraints);
1476 send_status(e, success);
1477 }
1478
1479 /* XXX todo: encrypt sensitive data with passphrase */
1480 static void
1481 process_lock_agent(SocketEntry *e, int lock)
1482 {
1483 int r, success = 0, delay;
1484 char *passwd;
1485 u_char passwdhash[LOCK_SIZE];
1486 static u_int fail_count = 0;
1487 size_t pwlen;
1488
1489 debug2_f("entering");
1490 /*
1491 * This is deliberately fatal: the user has requested that we lock,
1492 * but we can't parse their request properly. The only safe thing to
1493 * do is abort.
1494 */
1495 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0)
1496 fatal_fr(r, "parse");
1497 if (pwlen == 0) {
1498 debug("empty password not supported");
1499 } else if (locked && !lock) {
1500 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt),
1501 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0)
1502 fatal("bcrypt_pbkdf");
1503 if (timingsafe_bcmp(passwdhash, lock_pwhash, LOCK_SIZE) == 0) {
1504 debug("agent unlocked");
1505 locked = 0;
1506 fail_count = 0;
1507 explicit_bzero(lock_pwhash, sizeof(lock_pwhash));
1508 success = 1;
1509 } else {
1510 /* delay in 0.1s increments up to 10s */
1511 if (fail_count < 100)
1512 fail_count++;
1513 delay = 100000 * fail_count;
1514 debug("unlock failed, delaying %0.1lf seconds",
1515 (double)delay/1000000);
1516 usleep(delay);
1517 }
1518 explicit_bzero(passwdhash, sizeof(passwdhash));
1519 } else if (!locked && lock) {
1520 debug("agent locked");
1521 locked = 1;
1522 arc4random_buf(lock_salt, sizeof(lock_salt));
1523 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt),
1524 lock_pwhash, sizeof(lock_pwhash), LOCK_ROUNDS) < 0)
1525 fatal("bcrypt_pbkdf");
1526 success = 1;
1527 }
1528 freezero(passwd, pwlen);
1529 send_status(e, success);
1530 }
1531
1532 static void
1533 no_identities(SocketEntry *e)
1534 {
1535 struct sshbuf *msg;
1536 int r;
1537
1538 if ((msg = sshbuf_new()) == NULL)
1539 fatal_f("sshbuf_new failed");
1540 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
1541 (r = sshbuf_put_u32(msg, 0)) != 0 ||
1542 (r = sshbuf_put_stringb(e->output, msg)) != 0)
1543 fatal_fr(r, "compose");
1544 sshbuf_free(msg);
1545 }
1546
1547 #ifdef ENABLE_PKCS11
1548 /* Add an identity to idlist; takes ownership of 'key' and 'comment' */
1549 static void
1550 add_p11_identity(struct sshkey *key, char *comment, const char *provider,
1551 time_t death, u_int confirm, struct dest_constraint *dest_constraints,
1552 size_t ndest_constraints)
1553 {
1554 Identity *id;
1555
1556 if (lookup_identity(key) != NULL) {
1557 sshkey_free(key);
1558 free(comment);
1559 return;
1560 }
1561 id = xcalloc(1, sizeof(Identity));
1562 id->key = key;
1563 id->comment = comment;
1564 id->provider = xstrdup(provider);
1565 id->death = death;
1566 id->confirm = confirm;
1567 id->dest_constraints = dup_dest_constraints(dest_constraints,
1568 ndest_constraints);
1569 id->ndest_constraints = ndest_constraints;
1570 TAILQ_INSERT_TAIL(&idtab->idlist, id, next);
1571 idtab->nentries++;
1572 }
1573
1574 static void
1575 process_add_smartcard_key(SocketEntry *e)
1576 {
1577 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX];
1578 char **comments = NULL;
1579 int r, i, count = 0, success = 0, confirm = 0;
1580 u_int seconds = 0;
1581 time_t death = 0;
1582 struct sshkey **keys = NULL, *k;
1583 struct dest_constraint *dest_constraints = NULL;
1584 size_t j, ndest_constraints = 0, ncerts = 0;
1585 struct sshkey **certs = NULL;
1586 int cert_only = 0;
1587
1588 debug2_f("entering");
1589 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
1590 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) {
1591 error_fr(r, "parse");
1592 goto send;
1593 }
1594 if (parse_key_constraints(e->request, NULL, &death, &seconds, &confirm,
1595 NULL, &dest_constraints, &ndest_constraints, &cert_only,
1596 &ncerts, &certs) != 0) {
1597 error_f("failed to parse constraints");
1598 goto send;
1599 }
1600 dump_dest_constraints(__func__, dest_constraints, ndest_constraints);
1601 if (socket_is_remote(e) && !remote_add_provider) {
1602 verbose("failed PKCS#11 add of \"%.100s\": remote addition of "
1603 "providers is disabled", provider);
1604 goto send;
1605 }
1606 if (realpath(provider, canonical_provider) == NULL) {
1607 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s",
1608 provider, strerror(errno));
1609 goto send;
1610 }
1611 if (match_pattern_list(canonical_provider, allowed_providers, 0) != 1) {
1612 verbose("refusing PKCS#11 add of \"%.100s\": "
1613 "provider not allowed", canonical_provider);
1614 goto send;
1615 }
1616 debug_f("add %.100s", canonical_provider);
1617 if (lifetime && !death)
1618 death = monotime() + lifetime;
1619
1620 count = pkcs11_add_provider(canonical_provider, pin, &keys, &comments);
1621 for (i = 0; i < count; i++) {
1622 if (comments[i] == NULL || comments[i][0] == '\0') {
1623 free(comments[i]);
1624 comments[i] = xstrdup(canonical_provider);
1625 }
1626 for (j = 0; j < ncerts; j++) {
1627 if (!sshkey_is_cert(certs[j]))
1628 continue;
1629 if (!sshkey_equal_public(keys[i], certs[j]))
1630 continue;
1631 if (pkcs11_make_cert(keys[i], certs[j], &k) != 0)
1632 continue;
1633 add_p11_identity(k, xstrdup(comments[i]),
1634 canonical_provider, death, confirm,
1635 dest_constraints, ndest_constraints);
1636 success = 1;
1637 }
1638 if (!cert_only && lookup_identity(keys[i]) == NULL) {
1639 add_p11_identity(keys[i], comments[i],
1640 canonical_provider, death, confirm,
1641 dest_constraints, ndest_constraints);
1642 keys[i] = NULL; /* transferred */
1643 comments[i] = NULL; /* transferred */
1644 success = 1;
1645 }
1646 /* XXX update constraints for existing keys */
1647 sshkey_free(keys[i]);
1648 free(comments[i]);
1649 }
1650 send:
1651 free(pin);
1652 free(provider);
1653 free(keys);
1654 free(comments);
1655 free_dest_constraints(dest_constraints, ndest_constraints);
1656 for (j = 0; j < ncerts; j++)
1657 sshkey_free(certs[j]);
1658 free(certs);
1659 send_status(e, success);
1660 }
1661
1662 static void
1663 process_remove_smartcard_key(SocketEntry *e)
1664 {
1665 char *provider = NULL, *pin = NULL, canonical_provider[PATH_MAX];
1666 int r, success = 0;
1667 Identity *id, *nxt;
1668
1669 debug2_f("entering");
1670 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
1671 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0) {
1672 error_fr(r, "parse");
1673 goto send;
1674 }
1675 free(pin);
1676
1677 if (realpath(provider, canonical_provider) == NULL) {
1678 verbose("failed PKCS#11 add of \"%.100s\": realpath: %s",
1679 provider, strerror(errno));
1680 goto send;
1681 }
1682
1683 debug_f("remove %.100s", canonical_provider);
1684 for (id = TAILQ_FIRST(&idtab->idlist); id; id = nxt) {
1685 nxt = TAILQ_NEXT(id, next);
1686 /* Skip file--based keys */
1687 if (id->provider == NULL)
1688 continue;
1689 if (!strcmp(canonical_provider, id->provider)) {
1690 TAILQ_REMOVE(&idtab->idlist, id, next);
1691 free_identity(id);
1692 idtab->nentries--;
1693 }
1694 }
1695 if (pkcs11_del_provider(canonical_provider) == 0)
1696 success = 1;
1697 else
1698 error_f("pkcs11_del_provider failed");
1699 send:
1700 free(provider);
1701 send_status(e, success);
1702 }
1703 #endif /* ENABLE_PKCS11 */
1704
1705 static int
1706 process_ext_session_bind(SocketEntry *e)
1707 {
1708 int r, sid_match, key_match;
1709 struct sshkey *key = NULL;
1710 struct sshbuf *sid = NULL, *sig = NULL;
1711 char *fp = NULL;
1712 size_t i;
1713 u_char fwd = 0;
1714
1715 debug2_f("entering");
1716 e->session_bind_attempted = 1;
1717 if ((r = sshkey_froms(e->request, &key)) != 0 ||
1718 (r = sshbuf_froms(e->request, &sid)) != 0 ||
1719 (r = sshbuf_froms(e->request, &sig)) != 0 ||
1720 (r = sshbuf_get_u8(e->request, &fwd)) != 0) {
1721 error_fr(r, "parse");
1722 goto out;
1723 }
1724 if ((fp = sshkey_fingerprint(key, SSH_FP_HASH_DEFAULT,
1725 SSH_FP_DEFAULT)) == NULL)
1726 fatal_f("fingerprint failed");
1727 /* check signature with hostkey on session ID */
1728 if ((r = sshkey_verify(key, sshbuf_ptr(sig), sshbuf_len(sig),
1729 sshbuf_ptr(sid), sshbuf_len(sid), NULL, 0, NULL)) != 0) {
1730 error_fr(r, "sshkey_verify for %s %s", sshkey_type(key), fp);
1731 goto out;
1732 }
1733 /* check whether sid/key already recorded */
1734 for (i = 0; i < e->nsession_ids; i++) {
1735 if (!e->session_ids[i].forwarded) {
1736 error_f("attempt to bind session ID to socket "
1737 "previously bound for authentication attempt");
1738 r = -1;
1739 goto out;
1740 }
1741 sid_match = buf_equal(sid, e->session_ids[i].sid) == 0;
1742 key_match = sshkey_equal(key, e->session_ids[i].key);
1743 if (sid_match && key_match) {
1744 debug_f("session ID already recorded for %s %s",
1745 sshkey_type(key), fp);
1746 r = 0;
1747 goto out;
1748 } else if (sid_match) {
1749 error_f("session ID recorded against different key "
1750 "for %s %s", sshkey_type(key), fp);
1751 r = -1;
1752 goto out;
1753 }
1754 /*
1755 * new sid with previously-seen key can happen, e.g. multiple
1756 * connections to the same host.
1757 */
1758 }
1759 /* record new key/sid */
1760 if (e->nsession_ids >= AGENT_MAX_SESSION_IDS) {
1761 error_f("too many session IDs recorded");
1762 goto out;
1763 }
1764 e->session_ids = xrecallocarray(e->session_ids, e->nsession_ids,
1765 e->nsession_ids + 1, sizeof(*e->session_ids));
1766 i = e->nsession_ids++;
1767 debug_f("recorded %s %s (slot %zu of %d)", sshkey_type(key), fp, i,
1768 AGENT_MAX_SESSION_IDS);
1769 e->session_ids[i].key = key;
1770 e->session_ids[i].forwarded = fwd != 0;
1771 key = NULL; /* transferred */
1772 /* can't transfer sid; it's refcounted and scoped to request's life */
1773 if ((e->session_ids[i].sid = sshbuf_new()) == NULL)
1774 fatal_f("sshbuf_new");
1775 if ((r = sshbuf_putb(e->session_ids[i].sid, sid)) != 0)
1776 fatal_fr(r, "sshbuf_putb session ID");
1777 /* success */
1778 r = 0;
1779 out:
1780 free(fp);
1781 sshkey_free(key);
1782 sshbuf_free(sid);
1783 sshbuf_free(sig);
1784 return r == 0 ? 1 : 0;
1785 }
1786
1787 static void
1788 process_extension(SocketEntry *e)
1789 {
1790 int r, success = 0;
1791 char *name;
1792
1793 debug2_f("entering");
1794 if ((r = sshbuf_get_cstring(e->request, &name, NULL)) != 0) {
1795 error_fr(r, "parse");
1796 goto send;
1797 }
1798 if (strcmp(name, "session-bind@openssh.com") == 0)
1799 success = process_ext_session_bind(e);
1800 else
1801 debug_f("unsupported extension \"%s\"", name);
1802 free(name);
1803 send:
1804 send_status(e, success);
1805 }
1806 /*
1807 * dispatch incoming message.
1808 * returns 1 on success, 0 for incomplete messages or -1 on error.
1809 */
1810 static int
1811 process_message(u_int socknum)
1812 {
1813 u_int msg_len;
1814 u_char type;
1815 const u_char *cp;
1816 int r;
1817 SocketEntry *e;
1818
1819 if (socknum >= sockets_alloc)
1820 fatal_f("sock %u >= allocated %u", socknum, sockets_alloc);
1821 e = &sockets[socknum];
1822
1823 if (sshbuf_len(e->input) < 5)
1824 return 0; /* Incomplete message header. */
1825 cp = sshbuf_ptr(e->input);
1826 msg_len = PEEK_U32(cp);
1827 if (msg_len > AGENT_MAX_LEN) {
1828 debug_f("socket %u (fd=%d) message too long %u > %u",
1829 socknum, e->fd, msg_len, AGENT_MAX_LEN);
1830 return -1;
1831 }
1832 if (sshbuf_len(e->input) < msg_len + 4)
1833 return 0; /* Incomplete message body. */
1834
1835 /* move the current input to e->request */
1836 sshbuf_reset(e->request);
1837 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 ||
1838 (r = sshbuf_get_u8(e->request, &type)) != 0) {
1839 if (r == SSH_ERR_MESSAGE_INCOMPLETE ||
1840 r == SSH_ERR_STRING_TOO_LARGE) {
1841 error_fr(r, "parse");
1842 return -1;
1843 }
1844 fatal_fr(r, "parse");
1845 }
1846
1847 debug_f("socket %u (fd=%d) type %d", socknum, e->fd, type);
1848
1849 /* check whether agent is locked */
1850 if (locked && type != SSH_AGENTC_UNLOCK) {
1851 sshbuf_reset(e->request);
1852 switch (type) {
1853 case SSH2_AGENTC_REQUEST_IDENTITIES:
1854 /* send empty lists */
1855 no_identities(e);
1856 break;
1857 default:
1858 /* send a fail message for all other request types */
1859 send_status(e, 0);
1860 }
1861 return 1;
1862 }
1863
1864 switch (type) {
1865 case SSH_AGENTC_LOCK:
1866 case SSH_AGENTC_UNLOCK:
1867 process_lock_agent(e, type == SSH_AGENTC_LOCK);
1868 break;
1869 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
1870 process_remove_all_identities(e); /* safe for !WITH_SSH1 */
1871 break;
1872 /* ssh2 */
1873 case SSH2_AGENTC_SIGN_REQUEST:
1874 process_sign_request2(e);
1875 break;
1876 case SSH2_AGENTC_REQUEST_IDENTITIES:
1877 process_request_identities(e);
1878 break;
1879 case SSH2_AGENTC_ADD_IDENTITY:
1880 case SSH2_AGENTC_ADD_ID_CONSTRAINED:
1881 process_add_identity(e);
1882 break;
1883 case SSH2_AGENTC_REMOVE_IDENTITY:
1884 process_remove_identity(e);
1885 break;
1886 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
1887 process_remove_all_identities(e);
1888 break;
1889 #ifdef ENABLE_PKCS11
1890 case SSH_AGENTC_ADD_SMARTCARD_KEY:
1891 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
1892 process_add_smartcard_key(e);
1893 break;
1894 case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
1895 process_remove_smartcard_key(e);
1896 break;
1897 #endif /* ENABLE_PKCS11 */
1898 case SSH_AGENTC_EXTENSION:
1899 process_extension(e);
1900 break;
1901 default:
1902 /* Unknown message. Respond with failure. */
1903 error("Unknown message %d", type);
1904 sshbuf_reset(e->request);
1905 send_status(e, 0);
1906 break;
1907 }
1908 return 1;
1909 }
1910
1911 static void
1912 new_socket(sock_type type, int fd)
1913 {
1914 u_int i, old_alloc, new_alloc;
1915
1916 debug_f("type = %s", type == AUTH_CONNECTION ? "CONNECTION" :
1917 (type == AUTH_SOCKET ? "SOCKET" : "UNKNOWN"));
1918 if (type == AUTH_CONNECTION) {
1919 debug("xcount %d -> %d", xcount, xcount + 1);
1920 ++xcount;
1921 }
1922 set_nonblock(fd);
1923
1924 if (fd > max_fd)
1925 max_fd = fd;
1926
1927 for (i = 0; i < sockets_alloc; i++)
1928 if (sockets[i].type == AUTH_UNUSED) {
1929 sockets[i].fd = fd;
1930 if ((sockets[i].input = sshbuf_new()) == NULL ||
1931 (sockets[i].output = sshbuf_new()) == NULL ||
1932 (sockets[i].request = sshbuf_new()) == NULL)
1933 fatal_f("sshbuf_new failed");
1934 sockets[i].type = type;
1935 return;
1936 }
1937 old_alloc = sockets_alloc;
1938 new_alloc = sockets_alloc + 10;
1939 sockets = xrecallocarray(sockets, old_alloc, new_alloc,
1940 sizeof(sockets[0]));
1941 for (i = old_alloc; i < new_alloc; i++)
1942 sockets[i].type = AUTH_UNUSED;
1943 sockets_alloc = new_alloc;
1944 sockets[old_alloc].fd = fd;
1945 if ((sockets[old_alloc].input = sshbuf_new()) == NULL ||
1946 (sockets[old_alloc].output = sshbuf_new()) == NULL ||
1947 (sockets[old_alloc].request = sshbuf_new()) == NULL)
1948 fatal_f("sshbuf_new failed");
1949 sockets[old_alloc].type = type;
1950 }
1951
1952 static int
1953 handle_socket_read(u_int socknum)
1954 {
1955 struct sockaddr_un sunaddr;
1956 socklen_t slen;
1957 uid_t euid;
1958 gid_t egid;
1959 int fd;
1960
1961 slen = sizeof(sunaddr);
1962 fd = accept(sockets[socknum].fd, (struct sockaddr *)&sunaddr, &slen);
1963 if (fd == -1) {
1964 error("accept from AUTH_SOCKET: %s", strerror(errno));
1965 return -1;
1966 }
1967 if (getpeereid(fd, &euid, &egid) == -1) {
1968 error("getpeereid %d failed: %s", fd, strerror(errno));
1969 close(fd);
1970 return -1;
1971 }
1972 if ((euid != 0) && (getuid() != euid)) {
1973 error("uid mismatch: peer euid %u != uid %u",
1974 (u_int) euid, (u_int) getuid());
1975 close(fd);
1976 return -1;
1977 }
1978 new_socket(AUTH_CONNECTION, fd);
1979 return 0;
1980 }
1981
1982 static int
1983 handle_conn_read(u_int socknum)
1984 {
1985 char buf[AGENT_RBUF_LEN];
1986 ssize_t len;
1987 int r;
1988
1989 if ((len = read(sockets[socknum].fd, buf, sizeof(buf))) <= 0) {
1990 if (len == -1) {
1991 if (errno == EAGAIN || errno == EINTR)
1992 return 0;
1993 error_f("read error on socket %u (fd %d): %s",
1994 socknum, sockets[socknum].fd, strerror(errno));
1995 }
1996 return -1;
1997 }
1998 if ((r = sshbuf_put(sockets[socknum].input, buf, len)) != 0)
1999 fatal_fr(r, "compose");
2000 explicit_bzero(buf, sizeof(buf));
2001 for (;;) {
2002 if ((r = process_message(socknum)) == -1)
2003 return -1;
2004 else if (r == 0)
2005 break;
2006 }
2007 return 0;
2008 }
2009
2010 static int
2011 handle_conn_write(u_int socknum)
2012 {
2013 ssize_t len;
2014 int r;
2015
2016 if (sshbuf_len(sockets[socknum].output) == 0)
2017 return 0; /* shouldn't happen */
2018 if ((len = write(sockets[socknum].fd,
2019 sshbuf_ptr(sockets[socknum].output),
2020 sshbuf_len(sockets[socknum].output))) <= 0) {
2021 if (len == -1) {
2022 if (errno == EAGAIN || errno == EINTR)
2023 return 0;
2024 error_f("read error on socket %u (fd %d): %s",
2025 socknum, sockets[socknum].fd, strerror(errno));
2026 }
2027 return -1;
2028 }
2029 if ((r = sshbuf_consume(sockets[socknum].output, len)) != 0)
2030 fatal_fr(r, "consume");
2031 return 0;
2032 }
2033
2034 static void
2035 after_poll(struct pollfd *pfd, size_t npfd, u_int maxfds)
2036 {
2037 size_t i;
2038 u_int socknum, activefds = npfd;
2039
2040 for (i = 0; i < npfd; i++) {
2041 if (pfd[i].revents == 0)
2042 continue;
2043 /* Find sockets entry */
2044 for (socknum = 0; socknum < sockets_alloc; socknum++) {
2045 if (sockets[socknum].type != AUTH_SOCKET &&
2046 sockets[socknum].type != AUTH_CONNECTION)
2047 continue;
2048 if (pfd[i].fd == sockets[socknum].fd)
2049 break;
2050 }
2051 if (socknum >= sockets_alloc) {
2052 error_f("no socket for fd %d", pfd[i].fd);
2053 continue;
2054 }
2055 /* Process events */
2056 switch (sockets[socknum].type) {
2057 case AUTH_SOCKET:
2058 if ((pfd[i].revents & (POLLIN|POLLERR)) == 0)
2059 break;
2060 if (npfd > maxfds) {
2061 debug3("out of fds (active %u >= limit %u); "
2062 "skipping accept", activefds, maxfds);
2063 break;
2064 }
2065 if (handle_socket_read(socknum) == 0)
2066 activefds++;
2067 break;
2068 case AUTH_CONNECTION:
2069 if ((pfd[i].revents & (POLLIN|POLLHUP|POLLERR)) != 0 &&
2070 handle_conn_read(socknum) != 0)
2071 goto close_sock;
2072 if ((pfd[i].revents & (POLLOUT|POLLHUP)) != 0 &&
2073 handle_conn_write(socknum) != 0) {
2074 close_sock:
2075 if (activefds == 0)
2076 fatal("activefds == 0 at close_sock");
2077 close_socket(&sockets[socknum]);
2078 activefds--;
2079 break;
2080 }
2081 break;
2082 default:
2083 break;
2084 }
2085 }
2086 }
2087
2088 static int
2089 prepare_poll(struct pollfd **pfdp, size_t *npfdp, struct timespec *timeoutp, u_int maxfds)
2090 {
2091 struct pollfd *pfd = *pfdp;
2092 size_t i, j, npfd = 0;
2093 time_t deadline;
2094 int r;
2095
2096 /* Count active sockets */
2097 for (i = 0; i < sockets_alloc; i++) {
2098 switch (sockets[i].type) {
2099 case AUTH_SOCKET:
2100 case AUTH_CONNECTION:
2101 npfd++;
2102 break;
2103 case AUTH_UNUSED:
2104 break;
2105 default:
2106 fatal("Unknown socket type %d", sockets[i].type);
2107 break;
2108 }
2109 }
2110 if (npfd != *npfdp &&
2111 (pfd = recallocarray(pfd, *npfdp, npfd, sizeof(*pfd))) == NULL)
2112 fatal_f("recallocarray failed");
2113 *pfdp = pfd;
2114 *npfdp = npfd;
2115
2116 for (i = j = 0; i < sockets_alloc; i++) {
2117 switch (sockets[i].type) {
2118 case AUTH_SOCKET:
2119 if (npfd > maxfds) {
2120 debug3("out of fds (active %zu >= limit %u); "
2121 "skipping arming listener", npfd, maxfds);
2122 break;
2123 }
2124 pfd[j].fd = sockets[i].fd;
2125 pfd[j].revents = 0;
2126 pfd[j].events = POLLIN;
2127 j++;
2128 break;
2129 case AUTH_CONNECTION:
2130 pfd[j].fd = sockets[i].fd;
2131 pfd[j].revents = 0;
2132 /*
2133 * Only prepare to read if we can handle a full-size
2134 * input read buffer and enqueue a max size reply..
2135 */
2136 if ((r = sshbuf_check_reserve(sockets[i].input,
2137 AGENT_RBUF_LEN)) == 0 &&
2138 (r = sshbuf_check_reserve(sockets[i].output,
2139 AGENT_MAX_LEN)) == 0)
2140 pfd[j].events = POLLIN;
2141 else if (r != SSH_ERR_NO_BUFFER_SPACE)
2142 fatal_fr(r, "reserve");
2143 if (sshbuf_len(sockets[i].output) > 0)
2144 pfd[j].events |= POLLOUT;
2145 j++;
2146 break;
2147 default:
2148 break;
2149 }
2150 }
2151 deadline = reaper();
2152 if (parent_alive_interval != 0)
2153 deadline = (deadline == 0) ? parent_alive_interval :
2154 MINIMUM(deadline, parent_alive_interval);
2155 if (deadline != 0)
2156 ptimeout_deadline_sec(timeoutp, deadline);
2157 return (1);
2158 }
2159
2160 static void
2161 cleanup_socket(void)
2162 {
2163 if (cleanup_pid != 0 && getpid() != cleanup_pid)
2164 return;
2165 debug_f("cleanup");
2166 if (socket_name[0])
2167 unlink(socket_name);
2168 if (socket_dir[0])
2169 rmdir(socket_dir);
2170 }
2171
2172 void
2173 cleanup_exit(int i)
2174 {
2175 cleanup_socket();
2176 #ifdef ENABLE_PKCS11
2177 pkcs11_terminate();
2178 #endif
2179 _exit(i);
2180 }
2181
2182 static void
2183 cleanup_handler(int sig)
2184 {
2185 signalled = sig;
2186 }
2187
2188 static void
2189 check_parent_exists(void)
2190 {
2191 /*
2192 * If our parent has exited then getppid() will return (pid_t)1,
2193 * so testing for that should be safe.
2194 */
2195 if (parent_pid != -1 && getppid() != parent_pid) {
2196 /* printf("Parent has died - Authentication agent exiting.\n"); */
2197 cleanup_socket();
2198 _exit(2);
2199 }
2200 }
2201
2202 static void
2203 usage(void)
2204 {
2205 fprintf(stderr,
2206 "usage: ssh-agent [-c | -s] [-Ddx] [-a bind_address] [-E fingerprint_hash]\n"
2207 " [-O option] [-P allowed_providers] [-t life]\n"
2208 " ssh-agent [-a bind_address] [-E fingerprint_hash] [-O option]\n"
2209 " [-P allowed_providers] [-t life] command [arg ...]\n"
2210 " ssh-agent [-c | -s] -k\n");
2211 exit(1);
2212 }
2213
2214 int
2215 main(int ac, char **av)
2216 {
2217 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0;
2218 int sock, ch, result, saved_errno;
2219 char *shell, *format, *pidstr, *agentsocket = NULL;
2220 #ifdef HAVE_SETRLIMIT
2221 struct rlimit rlim;
2222 #endif
2223 extern int optind;
2224 extern char *optarg;
2225 pid_t pid;
2226 char pidstrbuf[1 + 3 * sizeof pid];
2227 size_t len;
2228 mode_t prev_mask;
2229 struct timespec timeout;
2230 struct pollfd *pfd = NULL;
2231 size_t npfd = 0;
2232 u_int maxfds;
2233 sigset_t nsigset, osigset;
2234
2235 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
2236 sanitise_stdfd();
2237
2238 /* drop */
2239 (void)setegid(getgid());
2240 (void)setgid(getgid());
2241 setuid(geteuid());
2242
2243 platform_disable_tracing(0); /* strict=no */
2244
2245 #ifdef RLIMIT_NOFILE
2246 if (getrlimit(RLIMIT_NOFILE, &rlim) == -1)
2247 fatal("%s: getrlimit: %s", __progname, strerror(errno));
2248 #endif
2249
2250 __progname = ssh_get_progname(av[0]);
2251 seed_rng();
2252
2253 while ((ch = getopt(ac, av, "cDdksE:a:O:P:t:x")) != -1) {
2254 switch (ch) {
2255 case 'E':
2256 fingerprint_hash = ssh_digest_alg_by_name(optarg);
2257 if (fingerprint_hash == -1)
2258 fatal("Invalid hash algorithm \"%s\"", optarg);
2259 break;
2260 case 'c':
2261 if (s_flag)
2262 usage();
2263 c_flag++;
2264 break;
2265 case 'k':
2266 k_flag++;
2267 break;
2268 case 'O':
2269 if (strcmp(optarg, "no-restrict-websafe") == 0)
2270 restrict_websafe = 0;
2271 else if (strcmp(optarg, "allow-remote-pkcs11") == 0)
2272 remote_add_provider = 1;
2273 else
2274 fatal("Unknown -O option");
2275 break;
2276 case 'P':
2277 if (allowed_providers != NULL)
2278 fatal("-P option already specified");
2279 allowed_providers = xstrdup(optarg);
2280 break;
2281 case 's':
2282 if (c_flag)
2283 usage();
2284 s_flag++;
2285 break;
2286 case 'd':
2287 if (d_flag || D_flag)
2288 usage();
2289 d_flag++;
2290 break;
2291 case 'D':
2292 if (d_flag || D_flag)
2293 usage();
2294 D_flag++;
2295 break;
2296 case 'a':
2297 agentsocket = optarg;
2298 break;
2299 case 't':
2300 if ((lifetime = convtime(optarg)) == -1) {
2301 fprintf(stderr, "Invalid lifetime\n");
2302 usage();
2303 }
2304 break;
2305 case 'x':
2306 xcount = 0;
2307 break;
2308 default:
2309 usage();
2310 }
2311 }
2312 ac -= optind;
2313 av += optind;
2314
2315 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag))
2316 usage();
2317
2318 if (allowed_providers == NULL)
2319 allowed_providers = xstrdup(DEFAULT_ALLOWED_PROVIDERS);
2320
2321 if (ac == 0 && !c_flag && !s_flag) {
2322 shell = getenv("SHELL");
2323 if (shell != NULL && (len = strlen(shell)) > 2 &&
2324 strncmp(shell + len - 3, "csh", 3) == 0)
2325 c_flag = 1;
2326 }
2327 if (k_flag) {
2328 const char *errstr = NULL;
2329
2330 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
2331 if (pidstr == NULL) {
2332 fprintf(stderr, "%s not set, cannot kill agent\n",
2333 SSH_AGENTPID_ENV_NAME);
2334 exit(1);
2335 }
2336 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
2337 if (errstr) {
2338 fprintf(stderr,
2339 "%s=\"%s\", which is not a good PID: %s\n",
2340 SSH_AGENTPID_ENV_NAME, pidstr, errstr);
2341 exit(1);
2342 }
2343 if (kill(pid, SIGTERM) == -1) {
2344 perror("kill");
2345 exit(1);
2346 }
2347 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
2348 printf(format, SSH_AUTHSOCKET_ENV_NAME);
2349 printf(format, SSH_AGENTPID_ENV_NAME);
2350 printf("echo Agent pid %ld killed;\n", (long)pid);
2351 exit(0);
2352 }
2353
2354 /*
2355 * Minimum file descriptors:
2356 * stdio (3) + listener (1) + syslog (1 maybe) + connection (1) +
2357 * a few spare for libc / stack protectors / sanitisers, etc.
2358 */
2359 #define SSH_AGENT_MIN_FDS (3+1+1+1+4)
2360 if (rlim.rlim_cur < SSH_AGENT_MIN_FDS)
2361 fatal("%s: file descriptor rlimit %lld too low (minimum %u)",
2362 __progname, (long long)rlim.rlim_cur, SSH_AGENT_MIN_FDS);
2363 maxfds = rlim.rlim_cur - SSH_AGENT_MIN_FDS;
2364
2365 parent_pid = getpid();
2366
2367 if (agentsocket == NULL) {
2368 /* Create private directory for agent socket */
2369 mktemp_proto(socket_dir, sizeof(socket_dir));
2370 if (mkdtemp(socket_dir) == NULL) {
2371 perror("mkdtemp: private socket dir");
2372 exit(1);
2373 }
2374 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
2375 (long)parent_pid);
2376 } else {
2377 /* Try to use specified agent socket */
2378 socket_dir[0] = '\0';
2379 strlcpy(socket_name, agentsocket, sizeof socket_name);
2380 }
2381
2382 /*
2383 * Create socket early so it will exist before command gets run from
2384 * the parent.
2385 */
2386 prev_mask = umask(0177);
2387 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0);
2388 if (sock < 0) {
2389 /* XXX - unix_listener() calls error() not perror() */
2390 *socket_name = '\0'; /* Don't unlink any existing file */
2391 cleanup_exit(1);
2392 }
2393 umask(prev_mask);
2394
2395 /*
2396 * Fork, and have the parent execute the command, if any, or present
2397 * the socket data. The child continues as the authentication agent.
2398 */
2399 if (D_flag || d_flag) {
2400 log_init(__progname,
2401 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO,
2402 SYSLOG_FACILITY_AUTH, 1);
2403 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
2404 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
2405 SSH_AUTHSOCKET_ENV_NAME);
2406 printf("echo Agent pid %ld;\n", (long)parent_pid);
2407 fflush(stdout);
2408 goto skip;
2409 }
2410 pid = fork();
2411 if (pid == -1) {
2412 perror("fork");
2413 cleanup_exit(1);
2414 }
2415 if (pid != 0) { /* Parent - execute the given command. */
2416 close(sock);
2417 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
2418 if (ac == 0) {
2419 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
2420 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
2421 SSH_AUTHSOCKET_ENV_NAME);
2422 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
2423 SSH_AGENTPID_ENV_NAME);
2424 printf("echo Agent pid %ld;\n", (long)pid);
2425 exit(0);
2426 }
2427 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
2428 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
2429 perror("setenv");
2430 exit(1);
2431 }
2432 execvp(av[0], av);
2433 perror(av[0]);
2434 exit(1);
2435 }
2436 /* child */
2437 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
2438
2439 if (setsid() == -1) {
2440 error("setsid: %s", strerror(errno));
2441 cleanup_exit(1);
2442 }
2443
2444 (void)chdir("/");
2445 if (stdfd_devnull(1, 1, 1) == -1)
2446 error_f("stdfd_devnull failed");
2447
2448 #ifdef HAVE_SETRLIMIT
2449 /* deny core dumps, since memory contains unencrypted private keys */
2450 rlim.rlim_cur = rlim.rlim_max = 0;
2451 if (setrlimit(RLIMIT_CORE, &rlim) == -1) {
2452 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
2453 cleanup_exit(1);
2454 }
2455 #endif
2456
2457 skip:
2458
2459 cleanup_pid = getpid();
2460
2461 #ifdef ENABLE_PKCS11
2462 pkcs11_init(0);
2463 #endif
2464 new_socket(AUTH_SOCKET, sock);
2465 if (ac > 0)
2466 parent_alive_interval = 10;
2467 idtab_init();
2468 ssh_signal(SIGPIPE, SIG_IGN);
2469 ssh_signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN);
2470 ssh_signal(SIGHUP, cleanup_handler);
2471 ssh_signal(SIGTERM, cleanup_handler);
2472
2473 sigemptyset(&nsigset);
2474 sigaddset(&nsigset, SIGINT);
2475 sigaddset(&nsigset, SIGHUP);
2476 sigaddset(&nsigset, SIGTERM);
2477
2478 if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1)
2479 fatal("%s: pledge: %s", __progname, strerror(errno));
2480 platform_pledge_agent();
2481
2482 while (1) {
2483 sigprocmask(SIG_BLOCK, &nsigset, &osigset);
2484 if (signalled != 0) {
2485 logit("exiting on signal %d", (int)signalled);
2486 cleanup_exit(2);
2487 }
2488 ptimeout_init(&timeout);
2489 prepare_poll(&pfd, &npfd, &timeout, maxfds);
2490 result = ppoll(pfd, npfd, ptimeout_get_tsp(&timeout), &osigset);
2491 sigprocmask(SIG_SETMASK, &osigset, NULL);
2492 saved_errno = errno;
2493 if (parent_alive_interval != 0)
2494 check_parent_exists();
2495 (void) reaper(); /* remove expired keys */
2496 if (result == -1) {
2497 if (saved_errno == EINTR)
2498 continue;
2499 fatal("poll: %s", strerror(saved_errno));
2500 } else if (result > 0)
2501 after_poll(pfd, npfd, maxfds);
2502 }
2503 /* NOTREACHED */
2504 }
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