1 /* $OpenBSD: ssh-agent.c,v 1.183 2014/02/02 03:44:31 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 __RCSID("$FreeBSD$");
39
40 #include <sys/types.h>
41 #include <sys/param.h>
42 #include <sys/resource.h>
43 #include <sys/stat.h>
44 #include <sys/socket.h>
45 #ifdef HAVE_SYS_TIME_H
46 # include <sys/time.h>
47 #endif
48 #ifdef HAVE_SYS_UN_H
49 # include <sys/un.h>
50 #endif
51 #include "openbsd-compat/sys-queue.h"
52
53 #include <openssl/evp.h>
54 #include "openbsd-compat/openssl-compat.h"
55
56 #include <errno.h>
57 #include <fcntl.h>
58 #ifdef HAVE_PATHS_H
59 # include <paths.h>
60 #endif
61 #include <signal.h>
62 #include <stdarg.h>
63 #include <stdio.h>
64 #include <stdlib.h>
65 #include <time.h>
66 #include <string.h>
67 #include <unistd.h>
68
69 #include "xmalloc.h"
70 #include "ssh.h"
71 #include "rsa.h"
72 #include "buffer.h"
73 #include "key.h"
74 #include "authfd.h"
75 #include "compat.h"
76 #include "log.h"
77 #include "misc.h"
78 #include "digest.h"
79
80 #ifdef ENABLE_PKCS11
81 #include "ssh-pkcs11.h"
82 #endif
83
84 #if defined(HAVE_SYS_PRCTL_H)
85 #include <sys/prctl.h> /* For prctl() and PR_SET_DUMPABLE */
86 #endif
87
88 typedef enum {
89 AUTH_UNUSED,
90 AUTH_SOCKET,
91 AUTH_CONNECTION
92 } sock_type;
93
94 typedef struct {
95 int fd;
96 sock_type type;
97 Buffer input;
98 Buffer output;
99 Buffer request;
100 } SocketEntry;
101
102 u_int sockets_alloc = 0;
103 SocketEntry *sockets = NULL;
104
105 typedef struct identity {
106 TAILQ_ENTRY(identity) next;
107 Key *key;
108 char *comment;
109 char *provider;
110 time_t death;
111 u_int confirm;
112 } Identity;
113
114 typedef struct {
115 int nentries;
116 TAILQ_HEAD(idqueue, identity) idlist;
117 } Idtab;
118
119 /* private key table, one per protocol version */
120 Idtab idtable[3];
121
122 int max_fd = 0;
123
124 /* pid of shell == parent of agent */
125 pid_t parent_pid = -1;
126 time_t parent_alive_interval = 0;
127
128 /* pathname and directory for AUTH_SOCKET */
129 char socket_name[MAXPATHLEN];
130 char socket_dir[MAXPATHLEN];
131
132 /* locking */
133 int locked = 0;
134 char *lock_passwd = NULL;
135
136 extern char *__progname;
137
138 /* Default lifetime in seconds (0 == forever) */
139 static long lifetime = 0;
140
141 /*
142 * Client connection count; incremented in new_socket() and decremented in
143 * close_socket(). When it reaches 0, ssh-agent will exit. Since it is
144 * normally initialized to 1, it will never reach 0. However, if the -x
145 * option is specified, it is initialized to 0 in main(); in that case,
146 * ssh-agent will exit as soon as it has had at least one client but no
147 * longer has any.
148 */
149 static int xcount = 1;
150
151 static void
close_socket(SocketEntry * e)152 close_socket(SocketEntry *e)
153 {
154 int last = 0;
155
156 if (e->type == AUTH_CONNECTION) {
157 debug("xcount %d -> %d", xcount, xcount - 1);
158 if (--xcount == 0)
159 last = 1;
160 }
161 close(e->fd);
162 e->fd = -1;
163 e->type = AUTH_UNUSED;
164 buffer_free(&e->input);
165 buffer_free(&e->output);
166 buffer_free(&e->request);
167 if (last)
168 cleanup_exit(0);
169 }
170
171 static void
idtab_init(void)172 idtab_init(void)
173 {
174 int i;
175
176 for (i = 0; i <=2; i++) {
177 TAILQ_INIT(&idtable[i].idlist);
178 idtable[i].nentries = 0;
179 }
180 }
181
182 /* return private key table for requested protocol version */
183 static Idtab *
idtab_lookup(int version)184 idtab_lookup(int version)
185 {
186 if (version < 1 || version > 2)
187 fatal("internal error, bad protocol version %d", version);
188 return &idtable[version];
189 }
190
191 static void
free_identity(Identity * id)192 free_identity(Identity *id)
193 {
194 key_free(id->key);
195 free(id->provider);
196 free(id->comment);
197 free(id);
198 }
199
200 /* return matching private key for given public key */
201 static Identity *
lookup_identity(Key * key,int version)202 lookup_identity(Key *key, int version)
203 {
204 Identity *id;
205
206 Idtab *tab = idtab_lookup(version);
207 TAILQ_FOREACH(id, &tab->idlist, next) {
208 if (key_equal(key, id->key))
209 return (id);
210 }
211 return (NULL);
212 }
213
214 /* Check confirmation of keysign request */
215 static int
confirm_key(Identity * id)216 confirm_key(Identity *id)
217 {
218 char *p;
219 int ret = -1;
220
221 p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
222 if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
223 id->comment, p))
224 ret = 0;
225 free(p);
226
227 return (ret);
228 }
229
230 /* send list of supported public keys to 'client' */
231 static void
process_request_identities(SocketEntry * e,int version)232 process_request_identities(SocketEntry *e, int version)
233 {
234 Idtab *tab = idtab_lookup(version);
235 Identity *id;
236 Buffer msg;
237
238 buffer_init(&msg);
239 buffer_put_char(&msg, (version == 1) ?
240 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
241 buffer_put_int(&msg, tab->nentries);
242 TAILQ_FOREACH(id, &tab->idlist, next) {
243 if (id->key->type == KEY_RSA1) {
244 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
245 buffer_put_bignum(&msg, id->key->rsa->e);
246 buffer_put_bignum(&msg, id->key->rsa->n);
247 } else {
248 u_char *blob;
249 u_int blen;
250 key_to_blob(id->key, &blob, &blen);
251 buffer_put_string(&msg, blob, blen);
252 free(blob);
253 }
254 buffer_put_cstring(&msg, id->comment);
255 }
256 buffer_put_int(&e->output, buffer_len(&msg));
257 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
258 buffer_free(&msg);
259 }
260
261 /* ssh1 only */
262 static void
process_authentication_challenge1(SocketEntry * e)263 process_authentication_challenge1(SocketEntry *e)
264 {
265 u_char buf[32], mdbuf[16], session_id[16];
266 u_int response_type;
267 BIGNUM *challenge;
268 Identity *id;
269 int i, len;
270 Buffer msg;
271 struct ssh_digest_ctx *md;
272 Key *key;
273
274 buffer_init(&msg);
275 key = key_new(KEY_RSA1);
276 if ((challenge = BN_new()) == NULL)
277 fatal("process_authentication_challenge1: BN_new failed");
278
279 (void) buffer_get_int(&e->request); /* ignored */
280 buffer_get_bignum(&e->request, key->rsa->e);
281 buffer_get_bignum(&e->request, key->rsa->n);
282 buffer_get_bignum(&e->request, challenge);
283
284 /* Only protocol 1.1 is supported */
285 if (buffer_len(&e->request) == 0)
286 goto failure;
287 buffer_get(&e->request, session_id, 16);
288 response_type = buffer_get_int(&e->request);
289 if (response_type != 1)
290 goto failure;
291
292 id = lookup_identity(key, 1);
293 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
294 Key *private = id->key;
295 /* Decrypt the challenge using the private key. */
296 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
297 goto failure;
298
299 /* The response is MD5 of decrypted challenge plus session id. */
300 len = BN_num_bytes(challenge);
301 if (len <= 0 || len > 32) {
302 logit("process_authentication_challenge: bad challenge length %d", len);
303 goto failure;
304 }
305 memset(buf, 0, 32);
306 BN_bn2bin(challenge, buf + 32 - len);
307 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
308 ssh_digest_update(md, buf, 32) < 0 ||
309 ssh_digest_update(md, session_id, 16) < 0 ||
310 ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0)
311 fatal("%s: md5 failed", __func__);
312 ssh_digest_free(md);
313
314 /* Send the response. */
315 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
316 for (i = 0; i < 16; i++)
317 buffer_put_char(&msg, mdbuf[i]);
318 goto send;
319 }
320
321 failure:
322 /* Unknown identity or protocol error. Send failure. */
323 buffer_put_char(&msg, SSH_AGENT_FAILURE);
324 send:
325 buffer_put_int(&e->output, buffer_len(&msg));
326 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
327 key_free(key);
328 BN_clear_free(challenge);
329 buffer_free(&msg);
330 }
331
332 /* ssh2 only */
333 static void
process_sign_request2(SocketEntry * e)334 process_sign_request2(SocketEntry *e)
335 {
336 u_char *blob, *data, *signature = NULL;
337 u_int blen, dlen, slen = 0;
338 extern int datafellows;
339 int odatafellows;
340 int ok = -1, flags;
341 Buffer msg;
342 Key *key;
343
344 datafellows = 0;
345
346 blob = buffer_get_string(&e->request, &blen);
347 data = buffer_get_string(&e->request, &dlen);
348
349 flags = buffer_get_int(&e->request);
350 odatafellows = datafellows;
351 if (flags & SSH_AGENT_OLD_SIGNATURE)
352 datafellows = SSH_BUG_SIGBLOB;
353
354 key = key_from_blob(blob, blen);
355 if (key != NULL) {
356 Identity *id = lookup_identity(key, 2);
357 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
358 ok = key_sign(id->key, &signature, &slen, data, dlen);
359 key_free(key);
360 }
361 buffer_init(&msg);
362 if (ok == 0) {
363 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
364 buffer_put_string(&msg, signature, slen);
365 } else {
366 buffer_put_char(&msg, SSH_AGENT_FAILURE);
367 }
368 buffer_put_int(&e->output, buffer_len(&msg));
369 buffer_append(&e->output, buffer_ptr(&msg),
370 buffer_len(&msg));
371 buffer_free(&msg);
372 free(data);
373 free(blob);
374 free(signature);
375 datafellows = odatafellows;
376 }
377
378 /* shared */
379 static void
process_remove_identity(SocketEntry * e,int version)380 process_remove_identity(SocketEntry *e, int version)
381 {
382 u_int blen, bits;
383 int success = 0;
384 Key *key = NULL;
385 u_char *blob;
386
387 switch (version) {
388 case 1:
389 key = key_new(KEY_RSA1);
390 bits = buffer_get_int(&e->request);
391 buffer_get_bignum(&e->request, key->rsa->e);
392 buffer_get_bignum(&e->request, key->rsa->n);
393
394 if (bits != key_size(key))
395 logit("Warning: identity keysize mismatch: actual %u, announced %u",
396 key_size(key), bits);
397 break;
398 case 2:
399 blob = buffer_get_string(&e->request, &blen);
400 key = key_from_blob(blob, blen);
401 free(blob);
402 break;
403 }
404 if (key != NULL) {
405 Identity *id = lookup_identity(key, version);
406 if (id != NULL) {
407 /*
408 * We have this key. Free the old key. Since we
409 * don't want to leave empty slots in the middle of
410 * the array, we actually free the key there and move
411 * all the entries between the empty slot and the end
412 * of the array.
413 */
414 Idtab *tab = idtab_lookup(version);
415 if (tab->nentries < 1)
416 fatal("process_remove_identity: "
417 "internal error: tab->nentries %d",
418 tab->nentries);
419 TAILQ_REMOVE(&tab->idlist, id, next);
420 free_identity(id);
421 tab->nentries--;
422 success = 1;
423 }
424 key_free(key);
425 }
426 buffer_put_int(&e->output, 1);
427 buffer_put_char(&e->output,
428 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
429 }
430
431 static void
process_remove_all_identities(SocketEntry * e,int version)432 process_remove_all_identities(SocketEntry *e, int version)
433 {
434 Idtab *tab = idtab_lookup(version);
435 Identity *id;
436
437 /* Loop over all identities and clear the keys. */
438 for (id = TAILQ_FIRST(&tab->idlist); id;
439 id = TAILQ_FIRST(&tab->idlist)) {
440 TAILQ_REMOVE(&tab->idlist, id, next);
441 free_identity(id);
442 }
443
444 /* Mark that there are no identities. */
445 tab->nentries = 0;
446
447 /* Send success. */
448 buffer_put_int(&e->output, 1);
449 buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
450 }
451
452 /* removes expired keys and returns number of seconds until the next expiry */
453 static time_t
reaper(void)454 reaper(void)
455 {
456 time_t deadline = 0, now = monotime();
457 Identity *id, *nxt;
458 int version;
459 Idtab *tab;
460
461 for (version = 1; version < 3; version++) {
462 tab = idtab_lookup(version);
463 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
464 nxt = TAILQ_NEXT(id, next);
465 if (id->death == 0)
466 continue;
467 if (now >= id->death) {
468 debug("expiring key '%s'", id->comment);
469 TAILQ_REMOVE(&tab->idlist, id, next);
470 free_identity(id);
471 tab->nentries--;
472 } else
473 deadline = (deadline == 0) ? id->death :
474 MIN(deadline, id->death);
475 }
476 }
477 if (deadline == 0 || deadline <= now)
478 return 0;
479 else
480 return (deadline - now);
481 }
482
483 static void
process_add_identity(SocketEntry * e,int version)484 process_add_identity(SocketEntry *e, int version)
485 {
486 Idtab *tab = idtab_lookup(version);
487 Identity *id;
488 int type, success = 0, confirm = 0;
489 char *comment;
490 time_t death = 0;
491 Key *k = NULL;
492
493 switch (version) {
494 case 1:
495 k = key_new_private(KEY_RSA1);
496 (void) buffer_get_int(&e->request); /* ignored */
497 buffer_get_bignum(&e->request, k->rsa->n);
498 buffer_get_bignum(&e->request, k->rsa->e);
499 buffer_get_bignum(&e->request, k->rsa->d);
500 buffer_get_bignum(&e->request, k->rsa->iqmp);
501
502 /* SSH and SSL have p and q swapped */
503 buffer_get_bignum(&e->request, k->rsa->q); /* p */
504 buffer_get_bignum(&e->request, k->rsa->p); /* q */
505
506 /* Generate additional parameters */
507 rsa_generate_additional_parameters(k->rsa);
508
509 /* enable blinding */
510 if (RSA_blinding_on(k->rsa, NULL) != 1) {
511 error("process_add_identity: RSA_blinding_on failed");
512 key_free(k);
513 goto send;
514 }
515 break;
516 case 2:
517 k = key_private_deserialize(&e->request);
518 if (k == NULL) {
519 buffer_clear(&e->request);
520 goto send;
521 }
522 break;
523 }
524 comment = buffer_get_string(&e->request, NULL);
525 if (k == NULL) {
526 free(comment);
527 goto send;
528 }
529 while (buffer_len(&e->request)) {
530 switch ((type = buffer_get_char(&e->request))) {
531 case SSH_AGENT_CONSTRAIN_LIFETIME:
532 death = monotime() + buffer_get_int(&e->request);
533 break;
534 case SSH_AGENT_CONSTRAIN_CONFIRM:
535 confirm = 1;
536 break;
537 default:
538 error("process_add_identity: "
539 "Unknown constraint type %d", type);
540 free(comment);
541 key_free(k);
542 goto send;
543 }
544 }
545 success = 1;
546 if (lifetime && !death)
547 death = monotime() + lifetime;
548 if ((id = lookup_identity(k, version)) == NULL) {
549 id = xcalloc(1, sizeof(Identity));
550 id->key = k;
551 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
552 /* Increment the number of identities. */
553 tab->nentries++;
554 } else {
555 key_free(k);
556 free(id->comment);
557 }
558 id->comment = comment;
559 id->death = death;
560 id->confirm = confirm;
561 send:
562 buffer_put_int(&e->output, 1);
563 buffer_put_char(&e->output,
564 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
565 }
566
567 /* XXX todo: encrypt sensitive data with passphrase */
568 static void
process_lock_agent(SocketEntry * e,int lock)569 process_lock_agent(SocketEntry *e, int lock)
570 {
571 int success = 0;
572 char *passwd;
573
574 passwd = buffer_get_string(&e->request, NULL);
575 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
576 locked = 0;
577 explicit_bzero(lock_passwd, strlen(lock_passwd));
578 free(lock_passwd);
579 lock_passwd = NULL;
580 success = 1;
581 } else if (!locked && lock) {
582 locked = 1;
583 lock_passwd = xstrdup(passwd);
584 success = 1;
585 }
586 explicit_bzero(passwd, strlen(passwd));
587 free(passwd);
588
589 buffer_put_int(&e->output, 1);
590 buffer_put_char(&e->output,
591 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
592 }
593
594 static void
no_identities(SocketEntry * e,u_int type)595 no_identities(SocketEntry *e, u_int type)
596 {
597 Buffer msg;
598
599 buffer_init(&msg);
600 buffer_put_char(&msg,
601 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
602 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
603 buffer_put_int(&msg, 0);
604 buffer_put_int(&e->output, buffer_len(&msg));
605 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
606 buffer_free(&msg);
607 }
608
609 #ifdef ENABLE_PKCS11
610 static void
process_add_smartcard_key(SocketEntry * e)611 process_add_smartcard_key(SocketEntry *e)
612 {
613 char *provider = NULL, *pin;
614 int i, type, version, count = 0, success = 0, confirm = 0;
615 time_t death = 0;
616 Key **keys = NULL, *k;
617 Identity *id;
618 Idtab *tab;
619
620 provider = buffer_get_string(&e->request, NULL);
621 pin = buffer_get_string(&e->request, NULL);
622
623 while (buffer_len(&e->request)) {
624 switch ((type = buffer_get_char(&e->request))) {
625 case SSH_AGENT_CONSTRAIN_LIFETIME:
626 death = monotime() + buffer_get_int(&e->request);
627 break;
628 case SSH_AGENT_CONSTRAIN_CONFIRM:
629 confirm = 1;
630 break;
631 default:
632 error("process_add_smartcard_key: "
633 "Unknown constraint type %d", type);
634 goto send;
635 }
636 }
637 if (lifetime && !death)
638 death = monotime() + lifetime;
639
640 count = pkcs11_add_provider(provider, pin, &keys);
641 for (i = 0; i < count; i++) {
642 k = keys[i];
643 version = k->type == KEY_RSA1 ? 1 : 2;
644 tab = idtab_lookup(version);
645 if (lookup_identity(k, version) == NULL) {
646 id = xcalloc(1, sizeof(Identity));
647 id->key = k;
648 id->provider = xstrdup(provider);
649 id->comment = xstrdup(provider); /* XXX */
650 id->death = death;
651 id->confirm = confirm;
652 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
653 tab->nentries++;
654 success = 1;
655 } else {
656 key_free(k);
657 }
658 keys[i] = NULL;
659 }
660 send:
661 free(pin);
662 free(provider);
663 free(keys);
664 buffer_put_int(&e->output, 1);
665 buffer_put_char(&e->output,
666 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
667 }
668
669 static void
process_remove_smartcard_key(SocketEntry * e)670 process_remove_smartcard_key(SocketEntry *e)
671 {
672 char *provider = NULL, *pin = NULL;
673 int version, success = 0;
674 Identity *id, *nxt;
675 Idtab *tab;
676
677 provider = buffer_get_string(&e->request, NULL);
678 pin = buffer_get_string(&e->request, NULL);
679 free(pin);
680
681 for (version = 1; version < 3; version++) {
682 tab = idtab_lookup(version);
683 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
684 nxt = TAILQ_NEXT(id, next);
685 /* Skip file--based keys */
686 if (id->provider == NULL)
687 continue;
688 if (!strcmp(provider, id->provider)) {
689 TAILQ_REMOVE(&tab->idlist, id, next);
690 free_identity(id);
691 tab->nentries--;
692 }
693 }
694 }
695 if (pkcs11_del_provider(provider) == 0)
696 success = 1;
697 else
698 error("process_remove_smartcard_key:"
699 " pkcs11_del_provider failed");
700 free(provider);
701 buffer_put_int(&e->output, 1);
702 buffer_put_char(&e->output,
703 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
704 }
705 #endif /* ENABLE_PKCS11 */
706
707 /* dispatch incoming messages */
708
709 static void
process_message(SocketEntry * e)710 process_message(SocketEntry *e)
711 {
712 u_int msg_len, type;
713 u_char *cp;
714
715 if (buffer_len(&e->input) < 5)
716 return; /* Incomplete message. */
717 cp = buffer_ptr(&e->input);
718 msg_len = get_u32(cp);
719 if (msg_len > 256 * 1024) {
720 close_socket(e);
721 return;
722 }
723 if (buffer_len(&e->input) < msg_len + 4)
724 return;
725
726 /* move the current input to e->request */
727 buffer_consume(&e->input, 4);
728 buffer_clear(&e->request);
729 buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
730 buffer_consume(&e->input, msg_len);
731 type = buffer_get_char(&e->request);
732
733 /* check wheter agent is locked */
734 if (locked && type != SSH_AGENTC_UNLOCK) {
735 buffer_clear(&e->request);
736 switch (type) {
737 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
738 case SSH2_AGENTC_REQUEST_IDENTITIES:
739 /* send empty lists */
740 no_identities(e, type);
741 break;
742 default:
743 /* send a fail message for all other request types */
744 buffer_put_int(&e->output, 1);
745 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
746 }
747 return;
748 }
749
750 debug("type %d", type);
751 switch (type) {
752 case SSH_AGENTC_LOCK:
753 case SSH_AGENTC_UNLOCK:
754 process_lock_agent(e, type == SSH_AGENTC_LOCK);
755 break;
756 /* ssh1 */
757 case SSH_AGENTC_RSA_CHALLENGE:
758 process_authentication_challenge1(e);
759 break;
760 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
761 process_request_identities(e, 1);
762 break;
763 case SSH_AGENTC_ADD_RSA_IDENTITY:
764 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
765 process_add_identity(e, 1);
766 break;
767 case SSH_AGENTC_REMOVE_RSA_IDENTITY:
768 process_remove_identity(e, 1);
769 break;
770 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
771 process_remove_all_identities(e, 1);
772 break;
773 /* ssh2 */
774 case SSH2_AGENTC_SIGN_REQUEST:
775 process_sign_request2(e);
776 break;
777 case SSH2_AGENTC_REQUEST_IDENTITIES:
778 process_request_identities(e, 2);
779 break;
780 case SSH2_AGENTC_ADD_IDENTITY:
781 case SSH2_AGENTC_ADD_ID_CONSTRAINED:
782 process_add_identity(e, 2);
783 break;
784 case SSH2_AGENTC_REMOVE_IDENTITY:
785 process_remove_identity(e, 2);
786 break;
787 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
788 process_remove_all_identities(e, 2);
789 break;
790 #ifdef ENABLE_PKCS11
791 case SSH_AGENTC_ADD_SMARTCARD_KEY:
792 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
793 process_add_smartcard_key(e);
794 break;
795 case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
796 process_remove_smartcard_key(e);
797 break;
798 #endif /* ENABLE_PKCS11 */
799 default:
800 /* Unknown message. Respond with failure. */
801 error("Unknown message %d", type);
802 buffer_clear(&e->request);
803 buffer_put_int(&e->output, 1);
804 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
805 break;
806 }
807 }
808
809 static void
new_socket(sock_type type,int fd)810 new_socket(sock_type type, int fd)
811 {
812 u_int i, old_alloc, new_alloc;
813
814 if (type == AUTH_CONNECTION) {
815 debug("xcount %d -> %d", xcount, xcount + 1);
816 ++xcount;
817 }
818 set_nonblock(fd);
819
820 if (fd > max_fd)
821 max_fd = fd;
822
823 for (i = 0; i < sockets_alloc; i++)
824 if (sockets[i].type == AUTH_UNUSED) {
825 sockets[i].fd = fd;
826 buffer_init(&sockets[i].input);
827 buffer_init(&sockets[i].output);
828 buffer_init(&sockets[i].request);
829 sockets[i].type = type;
830 return;
831 }
832 old_alloc = sockets_alloc;
833 new_alloc = sockets_alloc + 10;
834 sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
835 for (i = old_alloc; i < new_alloc; i++)
836 sockets[i].type = AUTH_UNUSED;
837 sockets_alloc = new_alloc;
838 sockets[old_alloc].fd = fd;
839 buffer_init(&sockets[old_alloc].input);
840 buffer_init(&sockets[old_alloc].output);
841 buffer_init(&sockets[old_alloc].request);
842 sockets[old_alloc].type = type;
843 }
844
845 static int
prepare_select(fd_set ** fdrp,fd_set ** fdwp,int * fdl,u_int * nallocp,struct timeval ** tvpp)846 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
847 struct timeval **tvpp)
848 {
849 u_int i, sz;
850 int n = 0;
851 static struct timeval tv;
852 time_t deadline;
853
854 for (i = 0; i < sockets_alloc; i++) {
855 switch (sockets[i].type) {
856 case AUTH_SOCKET:
857 case AUTH_CONNECTION:
858 n = MAX(n, sockets[i].fd);
859 break;
860 case AUTH_UNUSED:
861 break;
862 default:
863 fatal("Unknown socket type %d", sockets[i].type);
864 break;
865 }
866 }
867
868 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
869 if (*fdrp == NULL || sz > *nallocp) {
870 free(*fdrp);
871 free(*fdwp);
872 *fdrp = xmalloc(sz);
873 *fdwp = xmalloc(sz);
874 *nallocp = sz;
875 }
876 if (n < *fdl)
877 debug("XXX shrink: %d < %d", n, *fdl);
878 *fdl = n;
879 memset(*fdrp, 0, sz);
880 memset(*fdwp, 0, sz);
881
882 for (i = 0; i < sockets_alloc; i++) {
883 switch (sockets[i].type) {
884 case AUTH_SOCKET:
885 case AUTH_CONNECTION:
886 FD_SET(sockets[i].fd, *fdrp);
887 if (buffer_len(&sockets[i].output) > 0)
888 FD_SET(sockets[i].fd, *fdwp);
889 break;
890 default:
891 break;
892 }
893 }
894 deadline = reaper();
895 if (parent_alive_interval != 0)
896 deadline = (deadline == 0) ? parent_alive_interval :
897 MIN(deadline, parent_alive_interval);
898 if (deadline == 0) {
899 *tvpp = NULL;
900 } else {
901 tv.tv_sec = deadline;
902 tv.tv_usec = 0;
903 *tvpp = &tv;
904 }
905 return (1);
906 }
907
908 static void
after_select(fd_set * readset,fd_set * writeset)909 after_select(fd_set *readset, fd_set *writeset)
910 {
911 struct sockaddr_un sunaddr;
912 socklen_t slen;
913 char buf[1024];
914 int len, sock;
915 u_int i, orig_alloc;
916 uid_t euid;
917 gid_t egid;
918
919 for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
920 switch (sockets[i].type) {
921 case AUTH_UNUSED:
922 break;
923 case AUTH_SOCKET:
924 if (FD_ISSET(sockets[i].fd, readset)) {
925 slen = sizeof(sunaddr);
926 sock = accept(sockets[i].fd,
927 (struct sockaddr *)&sunaddr, &slen);
928 if (sock < 0) {
929 error("accept from AUTH_SOCKET: %s",
930 strerror(errno));
931 break;
932 }
933 if (getpeereid(sock, &euid, &egid) < 0) {
934 error("getpeereid %d failed: %s",
935 sock, strerror(errno));
936 close(sock);
937 break;
938 }
939 if ((euid != 0) && (getuid() != euid)) {
940 error("uid mismatch: "
941 "peer euid %u != uid %u",
942 (u_int) euid, (u_int) getuid());
943 close(sock);
944 break;
945 }
946 new_socket(AUTH_CONNECTION, sock);
947 }
948 break;
949 case AUTH_CONNECTION:
950 if (buffer_len(&sockets[i].output) > 0 &&
951 FD_ISSET(sockets[i].fd, writeset)) {
952 len = write(sockets[i].fd,
953 buffer_ptr(&sockets[i].output),
954 buffer_len(&sockets[i].output));
955 if (len == -1 && (errno == EAGAIN ||
956 errno == EWOULDBLOCK ||
957 errno == EINTR))
958 continue;
959 if (len <= 0) {
960 close_socket(&sockets[i]);
961 break;
962 }
963 buffer_consume(&sockets[i].output, len);
964 }
965 if (FD_ISSET(sockets[i].fd, readset)) {
966 len = read(sockets[i].fd, buf, sizeof(buf));
967 if (len == -1 && (errno == EAGAIN ||
968 errno == EWOULDBLOCK ||
969 errno == EINTR))
970 continue;
971 if (len <= 0) {
972 close_socket(&sockets[i]);
973 break;
974 }
975 buffer_append(&sockets[i].input, buf, len);
976 process_message(&sockets[i]);
977 }
978 break;
979 default:
980 fatal("Unknown type %d", sockets[i].type);
981 }
982 }
983
984 static void
cleanup_socket(void)985 cleanup_socket(void)
986 {
987 if (socket_name[0])
988 unlink(socket_name);
989 if (socket_dir[0])
990 rmdir(socket_dir);
991 }
992
993 void
cleanup_exit(int i)994 cleanup_exit(int i)
995 {
996 cleanup_socket();
997 _exit(i);
998 }
999
1000 /*ARGSUSED*/
1001 static void
cleanup_handler(int sig)1002 cleanup_handler(int sig)
1003 {
1004 cleanup_socket();
1005 #ifdef ENABLE_PKCS11
1006 pkcs11_terminate();
1007 #endif
1008 _exit(2);
1009 }
1010
1011 static void
check_parent_exists(void)1012 check_parent_exists(void)
1013 {
1014 /*
1015 * If our parent has exited then getppid() will return (pid_t)1,
1016 * so testing for that should be safe.
1017 */
1018 if (parent_pid != -1 && getppid() != parent_pid) {
1019 /* printf("Parent has died - Authentication agent exiting.\n"); */
1020 cleanup_socket();
1021 _exit(2);
1022 }
1023 }
1024
1025 static void
usage(void)1026 usage(void)
1027 {
1028 fprintf(stderr, "usage: %s [options] [command [arg ...]]\n",
1029 __progname);
1030 fprintf(stderr, "Options:\n");
1031 fprintf(stderr, " -c Generate C-shell commands on stdout.\n");
1032 fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n");
1033 fprintf(stderr, " -k Kill the current agent.\n");
1034 fprintf(stderr, " -d Debug mode.\n");
1035 fprintf(stderr, " -a socket Bind agent socket to given name.\n");
1036 fprintf(stderr, " -t life Default identity lifetime (seconds).\n");
1037 fprintf(stderr, " -x Exit when the last client disconnects.\n");
1038 exit(1);
1039 }
1040
1041 int
main(int ac,char ** av)1042 main(int ac, char **av)
1043 {
1044 int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1045 int sock, fd, ch, result, saved_errno;
1046 u_int nalloc;
1047 char *shell, *format, *pidstr, *agentsocket = NULL;
1048 fd_set *readsetp = NULL, *writesetp = NULL;
1049 struct sockaddr_un sunaddr;
1050 #ifdef HAVE_SETRLIMIT
1051 struct rlimit rlim;
1052 #endif
1053 int prev_mask;
1054 extern int optind;
1055 extern char *optarg;
1056 pid_t pid;
1057 char pidstrbuf[1 + 3 * sizeof pid];
1058 struct timeval *tvp = NULL;
1059 size_t len;
1060
1061 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1062 sanitise_stdfd();
1063
1064 /* drop */
1065 setegid(getgid());
1066 setgid(getgid());
1067 setuid(geteuid());
1068
1069 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1070 /* Disable ptrace on Linux without sgid bit */
1071 prctl(PR_SET_DUMPABLE, 0);
1072 #endif
1073
1074 OpenSSL_add_all_algorithms();
1075
1076 __progname = ssh_get_progname(av[0]);
1077 seed_rng();
1078
1079 while ((ch = getopt(ac, av, "cdksa:t:x")) != -1) {
1080 switch (ch) {
1081 case 'c':
1082 if (s_flag)
1083 usage();
1084 c_flag++;
1085 break;
1086 case 'k':
1087 k_flag++;
1088 break;
1089 case 's':
1090 if (c_flag)
1091 usage();
1092 s_flag++;
1093 break;
1094 case 'd':
1095 if (d_flag)
1096 usage();
1097 d_flag++;
1098 break;
1099 case 'a':
1100 agentsocket = optarg;
1101 break;
1102 case 't':
1103 if ((lifetime = convtime(optarg)) == -1) {
1104 fprintf(stderr, "Invalid lifetime\n");
1105 usage();
1106 }
1107 break;
1108 case 'x':
1109 xcount = 0;
1110 break;
1111 default:
1112 usage();
1113 }
1114 }
1115 ac -= optind;
1116 av += optind;
1117
1118 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1119 usage();
1120
1121 if (ac == 0 && !c_flag && !s_flag) {
1122 shell = getenv("SHELL");
1123 if (shell != NULL && (len = strlen(shell)) > 2 &&
1124 strncmp(shell + len - 3, "csh", 3) == 0)
1125 c_flag = 1;
1126 }
1127 if (k_flag) {
1128 const char *errstr = NULL;
1129
1130 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1131 if (pidstr == NULL) {
1132 fprintf(stderr, "%s not set, cannot kill agent\n",
1133 SSH_AGENTPID_ENV_NAME);
1134 exit(1);
1135 }
1136 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1137 if (errstr) {
1138 fprintf(stderr,
1139 "%s=\"%s\", which is not a good PID: %s\n",
1140 SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1141 exit(1);
1142 }
1143 if (kill(pid, SIGTERM) == -1) {
1144 perror("kill");
1145 exit(1);
1146 }
1147 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1148 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1149 printf(format, SSH_AGENTPID_ENV_NAME);
1150 printf("echo Agent pid %ld killed;\n", (long)pid);
1151 exit(0);
1152 }
1153 parent_pid = getpid();
1154
1155 if (agentsocket == NULL) {
1156 /* Create private directory for agent socket */
1157 mktemp_proto(socket_dir, sizeof(socket_dir));
1158 if (mkdtemp(socket_dir) == NULL) {
1159 perror("mkdtemp: private socket dir");
1160 exit(1);
1161 }
1162 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1163 (long)parent_pid);
1164 } else {
1165 /* Try to use specified agent socket */
1166 socket_dir[0] = '\0';
1167 strlcpy(socket_name, agentsocket, sizeof socket_name);
1168 }
1169
1170 /*
1171 * Create socket early so it will exist before command gets run from
1172 * the parent.
1173 */
1174 sock = socket(AF_UNIX, SOCK_STREAM, 0);
1175 if (sock < 0) {
1176 perror("socket");
1177 *socket_name = '\0'; /* Don't unlink any existing file */
1178 cleanup_exit(1);
1179 }
1180 memset(&sunaddr, 0, sizeof(sunaddr));
1181 sunaddr.sun_family = AF_UNIX;
1182 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1183 prev_mask = umask(0177);
1184 if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1185 perror("bind");
1186 *socket_name = '\0'; /* Don't unlink any existing file */
1187 umask(prev_mask);
1188 cleanup_exit(1);
1189 }
1190 umask(prev_mask);
1191 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1192 perror("listen");
1193 cleanup_exit(1);
1194 }
1195
1196 /*
1197 * Fork, and have the parent execute the command, if any, or present
1198 * the socket data. The child continues as the authentication agent.
1199 */
1200 if (d_flag) {
1201 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1202 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1203 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1204 SSH_AUTHSOCKET_ENV_NAME);
1205 printf("echo Agent pid %ld;\n", (long)parent_pid);
1206 goto skip;
1207 }
1208 pid = fork();
1209 if (pid == -1) {
1210 perror("fork");
1211 cleanup_exit(1);
1212 }
1213 if (pid != 0) { /* Parent - execute the given command. */
1214 close(sock);
1215 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1216 if (ac == 0) {
1217 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1218 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1219 SSH_AUTHSOCKET_ENV_NAME);
1220 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1221 SSH_AGENTPID_ENV_NAME);
1222 printf("echo Agent pid %ld;\n", (long)pid);
1223 exit(0);
1224 }
1225 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1226 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1227 perror("setenv");
1228 exit(1);
1229 }
1230 execvp(av[0], av);
1231 perror(av[0]);
1232 exit(1);
1233 }
1234 /* child */
1235 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1236
1237 if (setsid() == -1) {
1238 error("setsid: %s", strerror(errno));
1239 cleanup_exit(1);
1240 }
1241
1242 (void)chdir("/");
1243 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1244 /* XXX might close listen socket */
1245 (void)dup2(fd, STDIN_FILENO);
1246 (void)dup2(fd, STDOUT_FILENO);
1247 (void)dup2(fd, STDERR_FILENO);
1248 if (fd > 2)
1249 close(fd);
1250 }
1251
1252 #ifdef HAVE_SETRLIMIT
1253 /* deny core dumps, since memory contains unencrypted private keys */
1254 rlim.rlim_cur = rlim.rlim_max = 0;
1255 if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1256 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1257 cleanup_exit(1);
1258 }
1259 #endif
1260
1261 skip:
1262
1263 #ifdef ENABLE_PKCS11
1264 pkcs11_init(0);
1265 #endif
1266 new_socket(AUTH_SOCKET, sock);
1267 if (ac > 0)
1268 parent_alive_interval = 10;
1269 idtab_init();
1270 signal(SIGPIPE, SIG_IGN);
1271 signal(SIGINT, d_flag ? cleanup_handler : SIG_IGN);
1272 signal(SIGHUP, cleanup_handler);
1273 signal(SIGTERM, cleanup_handler);
1274 nalloc = 0;
1275
1276 while (1) {
1277 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1278 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1279 saved_errno = errno;
1280 if (parent_alive_interval != 0)
1281 check_parent_exists();
1282 (void) reaper(); /* remove expired keys */
1283 if (result < 0) {
1284 if (saved_errno == EINTR)
1285 continue;
1286 fatal("select: %s", strerror(saved_errno));
1287 } else if (result > 0)
1288 after_select(readsetp, writesetp);
1289 }
1290 /* NOTREACHED */
1291 }
1292