1 /* $OpenBSD: ssh-agent.c,v 1.162 2009/09/01 14:43:17 djm Exp $ */
2 /*
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright © 2013
5 * Thorsten “mirabilos” Glaser <tg@mirbsd.org>
6 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
7 * All rights reserved
8 * The authentication agent program.
9 *
10 * As far as I am concerned, the code I have written for this software
11 * can be used freely for any purpose. Any derived versions of this
12 * software must be clearly marked as such, and if the derived work is
13 * incompatible with the protocol description in the RFC file, it must be
14 * called by a name other than "ssh" or "Secure Shell".
15 *
16 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
17 *
18 * Redistribution and use in source and binary forms, with or without
19 * modification, are permitted provided that the following conditions
20 * are met:
21 * 1. Redistributions of source code must retain the above copyright
22 * notice, this list of conditions and the following disclaimer.
23 * 2. Redistributions in binary form must reproduce the above copyright
24 * notice, this list of conditions and the following disclaimer in the
25 * documentation and/or other materials provided with the distribution.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
37 */
38
39 #include <sys/param.h>
40 #include <sys/time.h>
41 #include <sys/queue.h>
42 #include <sys/resource.h>
43 #include <sys/socket.h>
44 #include <sys/un.h>
45
46 #include <openssl/evp.h>
47 #include <openssl/md5.h>
48
49 #include <errno.h>
50 #include <fcntl.h>
51 #include <paths.h>
52 #include <signal.h>
53 #include <stdlib.h>
54 #include <stdio.h>
55 #include <string.h>
56 #include <time.h>
57 #include <unistd.h>
58
59 #include "xmalloc.h"
60 #include "ssh.h"
61 #include "rsa.h"
62 #include "buffer.h"
63 #include "key.h"
64 #include "authfd.h"
65 #include "compat.h"
66 #include "log.h"
67 #include "misc.h"
68
69 __RCSID("$MirOS: src/usr.bin/ssh/ssh-agent.c,v 1.18 2013/10/31 20:07:14 tg Exp $");
70
71 #ifdef SMARTCARD
72 #include "scard.h"
73 #endif
74
75 typedef enum {
76 AUTH_UNUSED,
77 AUTH_SOCKET,
78 AUTH_CONNECTION
79 } sock_type;
80
81 typedef struct {
82 int fd;
83 sock_type type;
84 Buffer input;
85 Buffer output;
86 Buffer request;
87 } SocketEntry;
88
89 u_int sockets_alloc = 0;
90 SocketEntry *sockets = NULL;
91
92 typedef struct identity {
93 TAILQ_ENTRY(identity) next;
94 Key *key;
95 char *comment;
96 u_int death;
97 u_int confirm;
98 } Identity;
99
100 typedef struct {
101 int nentries;
102 TAILQ_HEAD(idqueue, identity) idlist;
103 } Idtab;
104
105 /* private key table, one per protocol version */
106 Idtab idtable[3];
107
108 int max_fd = 0;
109
110 /* pid of shell == parent of agent */
111 pid_t parent_pid = -1;
112 u_int parent_alive_interval = 0;
113
114 /* pathname and directory for AUTH_SOCKET */
115 char socket_name[MAXPATHLEN];
116 char socket_dir[MAXPATHLEN];
117
118 /* locking */
119 int locked = 0;
120 char *lock_passwd = NULL;
121
122 extern char *__progname;
123
124 /* Default lifetime (0 == forever) */
125 static int lifetime = 0;
126
127 static void
close_socket(SocketEntry * e)128 close_socket(SocketEntry *e)
129 {
130 close(e->fd);
131 e->fd = -1;
132 e->type = AUTH_UNUSED;
133 buffer_free(&e->input);
134 buffer_free(&e->output);
135 buffer_free(&e->request);
136 }
137
138 static void
idtab_init(void)139 idtab_init(void)
140 {
141 int i;
142
143 for (i = 0; i <=2; i++) {
144 TAILQ_INIT(&idtable[i].idlist);
145 idtable[i].nentries = 0;
146 }
147 }
148
149 /* return private key table for requested protocol version */
150 static Idtab *
idtab_lookup(int version)151 idtab_lookup(int version)
152 {
153 if (version < 1 || version > 2)
154 fatal("internal error, bad protocol version %d", version);
155 return &idtable[version];
156 }
157
158 static void
free_identity(Identity * id)159 free_identity(Identity *id)
160 {
161 key_free(id->key);
162 xfree(id->comment);
163 xfree(id);
164 }
165
166 /* return matching private key for given public key */
167 static Identity *
lookup_identity(Key * key,int version)168 lookup_identity(Key *key, int version)
169 {
170 Identity *id;
171
172 Idtab *tab = idtab_lookup(version);
173 TAILQ_FOREACH(id, &tab->idlist, next) {
174 if (key_equal(key, id->key))
175 return (id);
176 }
177 return (NULL);
178 }
179
180 /* Check confirmation of keysign request */
181 static int
confirm_key(Identity * id)182 confirm_key(Identity *id)
183 {
184 char *p;
185 int ret = -1;
186
187 p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
188 if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
189 id->comment, p))
190 ret = 0;
191 xfree(p);
192
193 return (ret);
194 }
195
196 /* send list of supported public keys to 'client' */
197 static void
process_request_identities(SocketEntry * e,int version)198 process_request_identities(SocketEntry *e, int version)
199 {
200 Idtab *tab = idtab_lookup(version);
201 Identity *id;
202 Buffer msg;
203
204 buffer_init(&msg);
205 buffer_put_char(&msg, (version == 1) ?
206 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
207 buffer_put_int(&msg, tab->nentries);
208 TAILQ_FOREACH(id, &tab->idlist, next) {
209 if (id->key->type == KEY_RSA1) {
210 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
211 buffer_put_bignum(&msg, id->key->rsa->e);
212 buffer_put_bignum(&msg, id->key->rsa->n);
213 } else {
214 u_char *blob;
215 u_int blen;
216 key_to_blob(id->key, &blob, &blen);
217 buffer_put_string(&msg, blob, blen);
218 xfree(blob);
219 }
220 buffer_put_cstring(&msg, id->comment);
221 }
222 buffer_put_int(&e->output, buffer_len(&msg));
223 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
224 buffer_free(&msg);
225 }
226
227 /* ssh1 only */
228 static void
process_authentication_challenge1(SocketEntry * e)229 process_authentication_challenge1(SocketEntry *e)
230 {
231 u_char buf[32], mdbuf[16], session_id[16];
232 u_int response_type;
233 BIGNUM *challenge;
234 Identity *id;
235 int i, len;
236 Buffer msg;
237 MD5_CTX md;
238 Key *key;
239
240 buffer_init(&msg);
241 key = key_new(KEY_RSA1);
242 if ((challenge = BN_new()) == NULL)
243 fatal("process_authentication_challenge1: BN_new failed");
244
245 (void) buffer_get_int(&e->request); /* ignored */
246 buffer_get_bignum(&e->request, key->rsa->e);
247 buffer_get_bignum(&e->request, key->rsa->n);
248 buffer_get_bignum(&e->request, challenge);
249
250 /* Only protocol 1.1 is supported */
251 if (buffer_len(&e->request) == 0)
252 goto failure;
253 buffer_get(&e->request, session_id, 16);
254 response_type = buffer_get_int(&e->request);
255 if (response_type != 1)
256 goto failure;
257
258 id = lookup_identity(key, 1);
259 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
260 Key *private = id->key;
261 /* Decrypt the challenge using the private key. */
262 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
263 goto failure;
264
265 /* The response is MD5 of decrypted challenge plus session id. */
266 len = BN_num_bytes(challenge);
267 if (len <= 0 || len > 32) {
268 logit("process_authentication_challenge: bad challenge length %d", len);
269 goto failure;
270 }
271 memset(buf, 0, 32);
272 BN_bn2bin(challenge, buf + 32 - len);
273 MD5_Init(&md);
274 MD5_Update(&md, buf, 32);
275 MD5_Update(&md, session_id, 16);
276 MD5_Final(mdbuf, &md);
277
278 /* Send the response. */
279 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
280 for (i = 0; i < 16; i++)
281 buffer_put_char(&msg, mdbuf[i]);
282 goto send;
283 }
284
285 failure:
286 /* Unknown identity or protocol error. Send failure. */
287 buffer_put_char(&msg, SSH_AGENT_FAILURE);
288 send:
289 buffer_put_int(&e->output, buffer_len(&msg));
290 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
291 key_free(key);
292 BN_clear_free(challenge);
293 buffer_free(&msg);
294 }
295
296 /* ssh2 only */
297 static void
process_sign_request2(SocketEntry * e)298 process_sign_request2(SocketEntry *e)
299 {
300 u_char *blob, *data, *signature = NULL;
301 u_int blen, dlen, slen = 0;
302 int odatafellows;
303 int ok = -1, flags;
304 Buffer msg;
305 Key *key;
306
307 datafellows = 0;
308
309 blob = buffer_get_string(&e->request, &blen);
310 data = buffer_get_string(&e->request, &dlen);
311
312 flags = buffer_get_int(&e->request);
313 odatafellows = datafellows;
314 if (flags & SSH_AGENT_OLD_SIGNATURE)
315 datafellows = SSH_BUG_SIGBLOB;
316
317 key = key_from_blob(blob, blen);
318 if (key != NULL) {
319 Identity *id = lookup_identity(key, 2);
320 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
321 ok = key_sign(id->key, &signature, &slen, data, dlen);
322 key_free(key);
323 }
324 buffer_init(&msg);
325 if (ok == 0) {
326 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
327 buffer_put_string(&msg, signature, slen);
328 } else {
329 buffer_put_char(&msg, SSH_AGENT_FAILURE);
330 }
331 buffer_put_int(&e->output, buffer_len(&msg));
332 buffer_append(&e->output, buffer_ptr(&msg),
333 buffer_len(&msg));
334 buffer_free(&msg);
335 xfree(data);
336 xfree(blob);
337 if (signature != NULL)
338 xfree(signature);
339 datafellows = odatafellows;
340 }
341
342 /* shared */
343 static void
process_remove_identity(SocketEntry * e,int version)344 process_remove_identity(SocketEntry *e, int version)
345 {
346 u_int blen, bits;
347 int success = 0;
348 Key *key = NULL;
349 u_char *blob;
350
351 switch (version) {
352 case 1:
353 key = key_new(KEY_RSA1);
354 bits = buffer_get_int(&e->request);
355 buffer_get_bignum(&e->request, key->rsa->e);
356 buffer_get_bignum(&e->request, key->rsa->n);
357
358 if (bits != key_size(key))
359 logit("Warning: identity keysize mismatch: actual %u, announced %u",
360 key_size(key), bits);
361 break;
362 case 2:
363 blob = buffer_get_string(&e->request, &blen);
364 key = key_from_blob(blob, blen);
365 xfree(blob);
366 break;
367 }
368 if (key != NULL) {
369 Identity *id = lookup_identity(key, version);
370 if (id != NULL) {
371 /*
372 * We have this key. Free the old key. Since we
373 * don't want to leave empty slots in the middle of
374 * the array, we actually free the key there and move
375 * all the entries between the empty slot and the end
376 * of the array.
377 */
378 Idtab *tab = idtab_lookup(version);
379 if (tab->nentries < 1)
380 fatal("process_remove_identity: "
381 "internal error: tab->nentries %d",
382 tab->nentries);
383 TAILQ_REMOVE(&tab->idlist, id, next);
384 free_identity(id);
385 tab->nentries--;
386 success = 1;
387 }
388 key_free(key);
389 }
390 buffer_put_int(&e->output, 1);
391 buffer_put_char(&e->output,
392 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
393 }
394
395 static void
process_remove_all_identities(SocketEntry * e,int version)396 process_remove_all_identities(SocketEntry *e, int version)
397 {
398 Idtab *tab = idtab_lookup(version);
399 Identity *id;
400
401 /* Loop over all identities and clear the keys. */
402 for (id = TAILQ_FIRST(&tab->idlist); id;
403 id = TAILQ_FIRST(&tab->idlist)) {
404 TAILQ_REMOVE(&tab->idlist, id, next);
405 free_identity(id);
406 }
407
408 /* Mark that there are no identities. */
409 tab->nentries = 0;
410
411 /* Send success. */
412 buffer_put_int(&e->output, 1);
413 buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
414 }
415
416 /* removes expired keys and returns number of seconds until the next expiry */
417 static u_int
reaper(void)418 reaper(void)
419 {
420 u_int deadline = 0, now = time(NULL);
421 Identity *id, *nxt;
422 int version;
423 Idtab *tab;
424
425 for (version = 1; version < 3; version++) {
426 tab = idtab_lookup(version);
427 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
428 nxt = TAILQ_NEXT(id, next);
429 if (id->death == 0)
430 continue;
431 if (now >= id->death) {
432 debug("expiring key '%s'", id->comment);
433 TAILQ_REMOVE(&tab->idlist, id, next);
434 free_identity(id);
435 tab->nentries--;
436 } else
437 deadline = (deadline == 0) ? id->death :
438 MIN(deadline, id->death);
439 }
440 }
441 if (deadline == 0 || deadline <= now)
442 return 0;
443 else
444 return (deadline - now);
445 }
446
447 static void
process_add_identity(SocketEntry * e,int version)448 process_add_identity(SocketEntry *e, int version)
449 {
450 Idtab *tab = idtab_lookup(version);
451 Identity *id;
452 int type, success = 0, death = 0, confirm = 0;
453 char *type_name, *comment;
454 Key *k = NULL;
455
456 switch (version) {
457 case 1:
458 k = key_new_private(KEY_RSA1);
459 (void) buffer_get_int(&e->request); /* ignored */
460 buffer_get_bignum(&e->request, k->rsa->n);
461 buffer_get_bignum(&e->request, k->rsa->e);
462 buffer_get_bignum(&e->request, k->rsa->d);
463 buffer_get_bignum(&e->request, k->rsa->iqmp);
464
465 /* SSH and SSL have p and q swapped */
466 buffer_get_bignum(&e->request, k->rsa->q); /* p */
467 buffer_get_bignum(&e->request, k->rsa->p); /* q */
468
469 /* Generate additional parameters */
470 rsa_generate_additional_parameters(k->rsa);
471 break;
472 case 2:
473 type_name = buffer_get_string(&e->request, NULL);
474 type = key_type_from_name(type_name);
475 xfree(type_name);
476 switch (type) {
477 case KEY_DSA:
478 k = key_new_private(type);
479 buffer_get_bignum2(&e->request, k->dsa->p);
480 buffer_get_bignum2(&e->request, k->dsa->q);
481 buffer_get_bignum2(&e->request, k->dsa->g);
482 buffer_get_bignum2(&e->request, k->dsa->pub_key);
483 buffer_get_bignum2(&e->request, k->dsa->priv_key);
484 break;
485 case KEY_RSA:
486 k = key_new_private(type);
487 buffer_get_bignum2(&e->request, k->rsa->n);
488 buffer_get_bignum2(&e->request, k->rsa->e);
489 buffer_get_bignum2(&e->request, k->rsa->d);
490 buffer_get_bignum2(&e->request, k->rsa->iqmp);
491 buffer_get_bignum2(&e->request, k->rsa->p);
492 buffer_get_bignum2(&e->request, k->rsa->q);
493
494 /* Generate additional parameters */
495 rsa_generate_additional_parameters(k->rsa);
496 break;
497 default:
498 buffer_clear(&e->request);
499 goto send;
500 }
501 break;
502 }
503 /* enable blinding */
504 switch (k->type) {
505 case KEY_RSA:
506 case KEY_RSA1:
507 if (RSA_blinding_on(k->rsa, NULL) != 1) {
508 error("process_add_identity: RSA_blinding_on failed");
509 key_free(k);
510 goto send;
511 }
512 break;
513 }
514 comment = buffer_get_string(&e->request, NULL);
515 if (k == NULL) {
516 xfree(comment);
517 goto send;
518 }
519 while (buffer_len(&e->request)) {
520 switch ((type = buffer_get_char(&e->request))) {
521 case SSH_AGENT_CONSTRAIN_LIFETIME:
522 death = time(NULL) + buffer_get_int(&e->request);
523 break;
524 case SSH_AGENT_CONSTRAIN_CONFIRM:
525 confirm = 1;
526 break;
527 default:
528 error("process_add_identity: "
529 "Unknown constraint type %d", type);
530 xfree(comment);
531 key_free(k);
532 goto send;
533 }
534 }
535 success = 1;
536 if (lifetime && !death)
537 death = time(NULL) + lifetime;
538 if ((id = lookup_identity(k, version)) == NULL) {
539 id = xmalloc(sizeof(Identity));
540 id->key = k;
541 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
542 /* Increment the number of identities. */
543 tab->nentries++;
544 } else {
545 key_free(k);
546 xfree(id->comment);
547 }
548 id->comment = comment;
549 id->death = death;
550 id->confirm = confirm;
551 send:
552 buffer_put_int(&e->output, 1);
553 buffer_put_char(&e->output,
554 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
555 }
556
557 /* XXX todo: encrypt sensitive data with passphrase */
558 static void
process_lock_agent(SocketEntry * e,int lock)559 process_lock_agent(SocketEntry *e, int lock)
560 {
561 int success = 0;
562 char *passwd;
563
564 passwd = buffer_get_string(&e->request, NULL);
565 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
566 locked = 0;
567 memset(lock_passwd, 0, strlen(lock_passwd));
568 xfree(lock_passwd);
569 lock_passwd = NULL;
570 success = 1;
571 } else if (!locked && lock) {
572 locked = 1;
573 lock_passwd = xstrdup(passwd);
574 success = 1;
575 }
576 memset(passwd, 0, strlen(passwd));
577 xfree(passwd);
578
579 buffer_put_int(&e->output, 1);
580 buffer_put_char(&e->output,
581 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
582 }
583
584 static void
no_identities(SocketEntry * e,u_int type)585 no_identities(SocketEntry *e, u_int type)
586 {
587 Buffer msg;
588
589 buffer_init(&msg);
590 buffer_put_char(&msg,
591 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
592 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
593 buffer_put_int(&msg, 0);
594 buffer_put_int(&e->output, buffer_len(&msg));
595 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
596 buffer_free(&msg);
597 }
598
599 #ifdef SMARTCARD
600 static void
process_add_smartcard_key(SocketEntry * e)601 process_add_smartcard_key(SocketEntry *e)
602 {
603 char *sc_reader_id = NULL, *pin;
604 int i, type, version, success = 0, death = 0, confirm = 0;
605 Key **keys, *k;
606 Identity *id;
607 Idtab *tab;
608
609 sc_reader_id = buffer_get_string(&e->request, NULL);
610 pin = buffer_get_string(&e->request, NULL);
611
612 while (buffer_len(&e->request)) {
613 switch ((type = buffer_get_char(&e->request))) {
614 case SSH_AGENT_CONSTRAIN_LIFETIME:
615 death = time(NULL) + buffer_get_int(&e->request);
616 break;
617 case SSH_AGENT_CONSTRAIN_CONFIRM:
618 confirm = 1;
619 break;
620 default:
621 error("process_add_smartcard_key: "
622 "Unknown constraint type %d", type);
623 xfree(sc_reader_id);
624 xfree(pin);
625 goto send;
626 }
627 }
628 if (lifetime && !death)
629 death = time(NULL) + lifetime;
630
631 keys = sc_get_keys(sc_reader_id, pin);
632 xfree(sc_reader_id);
633 xfree(pin);
634
635 if (keys == NULL || keys[0] == NULL) {
636 error("sc_get_keys failed");
637 goto send;
638 }
639 for (i = 0; keys[i] != NULL; i++) {
640 k = keys[i];
641 version = k->type == KEY_RSA1 ? 1 : 2;
642 tab = idtab_lookup(version);
643 if (lookup_identity(k, version) == NULL) {
644 id = xmalloc(sizeof(Identity));
645 id->key = k;
646 id->comment = sc_get_key_label(k);
647 id->death = death;
648 id->confirm = confirm;
649 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
650 tab->nentries++;
651 success = 1;
652 } else {
653 key_free(k);
654 }
655 keys[i] = NULL;
656 }
657 xfree(keys);
658 send:
659 buffer_put_int(&e->output, 1);
660 buffer_put_char(&e->output,
661 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
662 }
663
664 static void
process_remove_smartcard_key(SocketEntry * e)665 process_remove_smartcard_key(SocketEntry *e)
666 {
667 char *sc_reader_id = NULL, *pin;
668 int i, version, success = 0;
669 Key **keys, *k = NULL;
670 Identity *id;
671 Idtab *tab;
672
673 sc_reader_id = buffer_get_string(&e->request, NULL);
674 pin = buffer_get_string(&e->request, NULL);
675 keys = sc_get_keys(sc_reader_id, pin);
676 xfree(sc_reader_id);
677 xfree(pin);
678
679 if (keys == NULL || keys[0] == NULL) {
680 error("sc_get_keys failed");
681 goto send;
682 }
683 for (i = 0; keys[i] != NULL; i++) {
684 k = keys[i];
685 version = k->type == KEY_RSA1 ? 1 : 2;
686 if ((id = lookup_identity(k, version)) != NULL) {
687 tab = idtab_lookup(version);
688 TAILQ_REMOVE(&tab->idlist, id, next);
689 tab->nentries--;
690 free_identity(id);
691 success = 1;
692 }
693 key_free(k);
694 keys[i] = NULL;
695 }
696 xfree(keys);
697 send:
698 buffer_put_int(&e->output, 1);
699 buffer_put_char(&e->output,
700 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
701 }
702 #endif /* SMARTCARD */
703
704 /* dispatch incoming messages */
705
706 static void
process_message(SocketEntry * e)707 process_message(SocketEntry *e)
708 {
709 u_int msg_len, type;
710 u_char *cp;
711
712 if (buffer_len(&e->input) < 5)
713 return; /* Incomplete message. */
714 cp = buffer_ptr(&e->input);
715 msg_len = get_u32(cp);
716 if (msg_len > 256 * 1024) {
717 close_socket(e);
718 return;
719 }
720 if (buffer_len(&e->input) < msg_len + 4)
721 return;
722
723 /* move the current input to e->request */
724 buffer_consume(&e->input, 4);
725 buffer_clear(&e->request);
726 buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
727 buffer_consume(&e->input, msg_len);
728 type = buffer_get_char(&e->request);
729
730 /* check wheter agent is locked */
731 if (locked && type != SSH_AGENTC_UNLOCK) {
732 buffer_clear(&e->request);
733 switch (type) {
734 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
735 case SSH2_AGENTC_REQUEST_IDENTITIES:
736 /* send empty lists */
737 no_identities(e, type);
738 break;
739 default:
740 /* send a fail message for all other request types */
741 buffer_put_int(&e->output, 1);
742 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
743 }
744 return;
745 }
746
747 debug("type %d", type);
748 switch (type) {
749 case SSH_AGENTC_LOCK:
750 case SSH_AGENTC_UNLOCK:
751 process_lock_agent(e, type == SSH_AGENTC_LOCK);
752 break;
753 /* ssh1 */
754 case SSH_AGENTC_RSA_CHALLENGE:
755 process_authentication_challenge1(e);
756 break;
757 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
758 process_request_identities(e, 1);
759 break;
760 case SSH_AGENTC_ADD_RSA_IDENTITY:
761 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
762 process_add_identity(e, 1);
763 break;
764 case SSH_AGENTC_REMOVE_RSA_IDENTITY:
765 process_remove_identity(e, 1);
766 break;
767 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
768 process_remove_all_identities(e, 1);
769 break;
770 /* ssh2 */
771 case SSH2_AGENTC_SIGN_REQUEST:
772 process_sign_request2(e);
773 break;
774 case SSH2_AGENTC_REQUEST_IDENTITIES:
775 process_request_identities(e, 2);
776 break;
777 case SSH2_AGENTC_ADD_IDENTITY:
778 case SSH2_AGENTC_ADD_ID_CONSTRAINED:
779 process_add_identity(e, 2);
780 break;
781 case SSH2_AGENTC_REMOVE_IDENTITY:
782 process_remove_identity(e, 2);
783 break;
784 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
785 process_remove_all_identities(e, 2);
786 break;
787 #ifdef SMARTCARD
788 case SSH_AGENTC_ADD_SMARTCARD_KEY:
789 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
790 process_add_smartcard_key(e);
791 break;
792 case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
793 process_remove_smartcard_key(e);
794 break;
795 #endif /* SMARTCARD */
796 default:
797 /* Unknown message. Respond with failure. */
798 error("Unknown message %d", type);
799 buffer_clear(&e->request);
800 buffer_put_int(&e->output, 1);
801 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
802 break;
803 }
804 }
805
806 static void
new_socket(sock_type type,int fd)807 new_socket(sock_type type, int fd)
808 {
809 u_int i, old_alloc, new_alloc;
810
811 set_nonblock(fd);
812
813 if (fd > max_fd)
814 max_fd = fd;
815
816 for (i = 0; i < sockets_alloc; i++)
817 if (sockets[i].type == AUTH_UNUSED) {
818 sockets[i].fd = fd;
819 buffer_init(&sockets[i].input);
820 buffer_init(&sockets[i].output);
821 buffer_init(&sockets[i].request);
822 sockets[i].type = type;
823 return;
824 }
825 old_alloc = sockets_alloc;
826 new_alloc = sockets_alloc + 10;
827 sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
828 for (i = old_alloc; i < new_alloc; i++)
829 sockets[i].type = AUTH_UNUSED;
830 sockets_alloc = new_alloc;
831 sockets[old_alloc].fd = fd;
832 buffer_init(&sockets[old_alloc].input);
833 buffer_init(&sockets[old_alloc].output);
834 buffer_init(&sockets[old_alloc].request);
835 sockets[old_alloc].type = type;
836 }
837
838 static int
prepare_select(fd_set ** fdrp,fd_set ** fdwp,int * fdl,u_int * nallocp,struct timeval ** tvpp)839 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
840 struct timeval **tvpp)
841 {
842 u_int i, sz, deadline;
843 int n = 0;
844 static struct timeval tv;
845
846 for (i = 0; i < sockets_alloc; i++) {
847 switch (sockets[i].type) {
848 case AUTH_SOCKET:
849 case AUTH_CONNECTION:
850 n = MAX(n, sockets[i].fd);
851 break;
852 case AUTH_UNUSED:
853 break;
854 default:
855 fatal("Unknown socket type %d", sockets[i].type);
856 break;
857 }
858 }
859
860 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
861 if (*fdrp == NULL || sz > *nallocp) {
862 if (*fdrp)
863 xfree(*fdrp);
864 if (*fdwp)
865 xfree(*fdwp);
866 *fdrp = xmalloc(sz);
867 *fdwp = xmalloc(sz);
868 *nallocp = sz;
869 }
870 if (n < *fdl)
871 debug("XXX shrink: %d < %d", n, *fdl);
872 *fdl = n;
873 memset(*fdrp, 0, sz);
874 memset(*fdwp, 0, sz);
875
876 for (i = 0; i < sockets_alloc; i++) {
877 switch (sockets[i].type) {
878 case AUTH_SOCKET:
879 case AUTH_CONNECTION:
880 FD_SET(sockets[i].fd, *fdrp);
881 if (buffer_len(&sockets[i].output) > 0)
882 FD_SET(sockets[i].fd, *fdwp);
883 break;
884 default:
885 break;
886 }
887 }
888 deadline = reaper();
889 if (parent_alive_interval != 0)
890 deadline = (deadline == 0) ? parent_alive_interval :
891 MIN(deadline, parent_alive_interval);
892 if (deadline == 0) {
893 *tvpp = NULL;
894 } else {
895 tv.tv_sec = deadline;
896 tv.tv_usec = 0;
897 *tvpp = &tv;
898 }
899 return (1);
900 }
901
902 static void
after_select(fd_set * readset,fd_set * writeset)903 after_select(fd_set *readset, fd_set *writeset)
904 {
905 struct sockaddr_un sunaddr;
906 socklen_t slen;
907 char buf[1024];
908 int len, sock;
909 u_int i, orig_alloc;
910 uid_t euid;
911 gid_t egid;
912
913 for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
914 switch (sockets[i].type) {
915 case AUTH_UNUSED:
916 break;
917 case AUTH_SOCKET:
918 if (FD_ISSET(sockets[i].fd, readset)) {
919 slen = sizeof(sunaddr);
920 sock = accept(sockets[i].fd,
921 (struct sockaddr *)&sunaddr, &slen);
922 if (sock < 0) {
923 error("accept from AUTH_SOCKET: %s",
924 strerror(errno));
925 break;
926 }
927 if (getpeereid(sock, &euid, &egid) < 0) {
928 error("getpeereid %d failed: %s",
929 sock, strerror(errno));
930 close(sock);
931 break;
932 }
933 if ((euid != 0) && (getuid() != euid)) {
934 error("uid mismatch: "
935 "peer euid %u != uid %u",
936 (u_int) euid, (u_int) getuid());
937 close(sock);
938 break;
939 }
940 new_socket(AUTH_CONNECTION, sock);
941 }
942 break;
943 case AUTH_CONNECTION:
944 if (buffer_len(&sockets[i].output) > 0 &&
945 FD_ISSET(sockets[i].fd, writeset)) {
946 len = write(sockets[i].fd,
947 buffer_ptr(&sockets[i].output),
948 buffer_len(&sockets[i].output));
949 if (len == -1 && (errno == EAGAIN ||
950 errno == EINTR))
951 continue;
952 if (len <= 0) {
953 close_socket(&sockets[i]);
954 break;
955 }
956 buffer_consume(&sockets[i].output, len);
957 }
958 if (FD_ISSET(sockets[i].fd, readset)) {
959 len = read(sockets[i].fd, buf, sizeof(buf));
960 if (len == -1 && (errno == EAGAIN ||
961 errno == EINTR))
962 continue;
963 if (len <= 0) {
964 close_socket(&sockets[i]);
965 break;
966 }
967 buffer_append(&sockets[i].input, buf, len);
968 process_message(&sockets[i]);
969 }
970 break;
971 default:
972 fatal("Unknown type %d", sockets[i].type);
973 }
974 }
975
976 static void
cleanup_socket(void)977 cleanup_socket(void)
978 {
979 if (socket_name[0])
980 unlink(socket_name);
981 if (socket_dir[0])
982 rmdir(socket_dir);
983 }
984
985 __dead void
cleanup_exit(int i)986 cleanup_exit(int i)
987 {
988 cleanup_socket();
989 _exit(i);
990 }
991
992 /*ARGSUSED*/
993 static __dead void
cleanup_handler(int sig)994 cleanup_handler(int sig __attribute__((__unused__)))
995 {
996 cleanup_socket();
997 _exit(2);
998 }
999
1000 static void
check_parent_exists(void)1001 check_parent_exists(void)
1002 {
1003 if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
1004 /* printf("Parent has died - Authentication agent exiting.\n"); */
1005 cleanup_socket();
1006 _exit(2);
1007 }
1008 }
1009
1010 static __dead void
usage(void)1011 usage(void)
1012 {
1013 fprintf(stderr, "usage: %s [options] [command [arg ...]]\n",
1014 __progname);
1015 fprintf(stderr, "Options:\n");
1016 fprintf(stderr, " -c Generate C-shell commands on stdout.\n");
1017 fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n");
1018 fprintf(stderr, " -k Kill the current agent.\n");
1019 fprintf(stderr, " -d Debug mode.\n");
1020 fprintf(stderr, " -a socket Bind agent socket to given name.\n");
1021 fprintf(stderr, " -t life Default identity lifetime (seconds).\n");
1022 exit(1);
1023 }
1024
1025 int
main(int ac,char ** av)1026 main(int ac, char **av)
1027 {
1028 int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1029 int sock, fd, ch, result, saved_errno;
1030 u_int nalloc;
1031 char *shell, *pidstr, *agentsocket = NULL;
1032 const char *format;
1033 fd_set *readsetp = NULL, *writesetp = NULL;
1034 struct sockaddr_un sunaddr;
1035 struct rlimit rlim;
1036 pid_t pid;
1037 char pidstrbuf[1 + 3 * sizeof pid];
1038 struct timeval *tvp = NULL;
1039 size_t len;
1040
1041 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1042 sanitise_stdfd();
1043
1044 /* drop */
1045 setegid(getgid());
1046 setgid(getgid());
1047
1048 SSLeay_add_all_algorithms();
1049
1050 while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1051 switch (ch) {
1052 case 'c':
1053 if (s_flag)
1054 usage();
1055 c_flag++;
1056 break;
1057 case 'k':
1058 k_flag++;
1059 break;
1060 case 's':
1061 if (c_flag)
1062 usage();
1063 s_flag++;
1064 break;
1065 case 'd':
1066 if (d_flag)
1067 usage();
1068 d_flag++;
1069 break;
1070 case 'a':
1071 agentsocket = optarg;
1072 break;
1073 case 't':
1074 if ((lifetime = convtime(optarg)) == -1) {
1075 fprintf(stderr, "Invalid lifetime\n");
1076 usage();
1077 }
1078 break;
1079 default:
1080 usage();
1081 }
1082 }
1083 ac -= optind;
1084 av += optind;
1085
1086 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1087 usage();
1088
1089 if (ac == 0 && !c_flag && !s_flag) {
1090 shell = getenv("SHELL");
1091 if (shell != NULL && (len = strlen(shell)) > 2 &&
1092 strncmp(shell + len - 3, "csh", 3) == 0)
1093 c_flag = 1;
1094 }
1095 if (k_flag) {
1096 const char *errstr = NULL;
1097
1098 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1099 if (pidstr == NULL) {
1100 fprintf(stderr, "%s not set, cannot kill agent\n",
1101 SSH_AGENTPID_ENV_NAME);
1102 exit(1);
1103 }
1104 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1105 if (errstr) {
1106 fprintf(stderr,
1107 "%s=\"%s\", which is not a good PID: %s\n",
1108 SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1109 exit(1);
1110 }
1111 if (kill(pid, SIGTERM) == -1) {
1112 perror("kill");
1113 exit(1);
1114 }
1115 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1116 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1117 printf(format, SSH_AGENTPID_ENV_NAME);
1118 printf("echo Agent pid %ld killed;\n", (long)pid);
1119 exit(0);
1120 }
1121 parent_pid = getpid();
1122
1123 if (agentsocket == NULL) {
1124 /* Create private directory for agent socket */
1125 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1126 if (mkdtemp(socket_dir) == NULL) {
1127 perror("mkdtemp: private socket dir");
1128 exit(1);
1129 }
1130 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1131 (long)parent_pid);
1132 } else {
1133 /* Try to use specified agent socket */
1134 socket_dir[0] = '\0';
1135 strlcpy(socket_name, agentsocket, sizeof socket_name);
1136 }
1137
1138 /*
1139 * Create socket early so it will exist before command gets run from
1140 * the parent.
1141 */
1142 sock = socket(AF_UNIX, SOCK_STREAM, 0);
1143 if (sock < 0) {
1144 perror("socket");
1145 *socket_name = '\0'; /* Don't unlink any existing file */
1146 cleanup_exit(1);
1147 }
1148 memset(&sunaddr, 0, sizeof(sunaddr));
1149 sunaddr.sun_family = AF_UNIX;
1150 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1151 if (bind(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) {
1152 perror("bind");
1153 *socket_name = '\0'; /* Don't unlink any existing file */
1154 cleanup_exit(1);
1155 }
1156 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1157 perror("listen");
1158 cleanup_exit(1);
1159 }
1160
1161 /*
1162 * Fork, and have the parent execute the command, if any, or present
1163 * the socket data. The child continues as the authentication agent.
1164 */
1165 if (d_flag) {
1166 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1167 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1168 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1169 SSH_AUTHSOCKET_ENV_NAME);
1170 printf("echo Agent pid %ld;\n", (long)parent_pid);
1171 goto skip;
1172 }
1173 pid = fork();
1174 if (pid == -1) {
1175 perror("fork");
1176 cleanup_exit(1);
1177 }
1178 if (pid != 0) { /* Parent - execute the given command. */
1179 close(sock);
1180 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1181 if (ac == 0) {
1182 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1183 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1184 SSH_AUTHSOCKET_ENV_NAME);
1185 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1186 SSH_AGENTPID_ENV_NAME);
1187 printf("echo Agent pid %ld;\n", (long)pid);
1188 exit(0);
1189 }
1190 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1191 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1192 perror("setenv");
1193 exit(1);
1194 }
1195 execvp(av[0], av);
1196 perror(av[0]);
1197 exit(1);
1198 }
1199 /* child */
1200 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1201
1202 if (setsid() == -1) {
1203 error("setsid: %s", strerror(errno));
1204 cleanup_exit(1);
1205 }
1206
1207 (void)chdir("/");
1208 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1209 /* XXX might close listen socket */
1210 (void)dup2(fd, STDIN_FILENO);
1211 (void)dup2(fd, STDOUT_FILENO);
1212 (void)dup2(fd, STDERR_FILENO);
1213 if (fd > 2)
1214 close(fd);
1215 }
1216
1217 /* deny core dumps, since memory contains unencrypted private keys */
1218 rlim.rlim_cur = rlim.rlim_max = 0;
1219 if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1220 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1221 cleanup_exit(1);
1222 }
1223
1224 skip:
1225 new_socket(AUTH_SOCKET, sock);
1226 if (ac > 0)
1227 parent_alive_interval = 10;
1228 idtab_init();
1229 if (!d_flag)
1230 signal(SIGINT, SIG_IGN);
1231 signal(SIGPIPE, SIG_IGN);
1232 signal(SIGHUP, cleanup_handler);
1233 signal(SIGTERM, cleanup_handler);
1234 nalloc = 0;
1235
1236 while (1) {
1237 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1238 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1239 saved_errno = errno;
1240 if (parent_alive_interval != 0)
1241 check_parent_exists();
1242 (void) reaper(); /* remove expired keys */
1243 if (result < 0) {
1244 if (saved_errno == EINTR)
1245 continue;
1246 fatal("select: %s", strerror(saved_errno));
1247 } else if (result > 0)
1248 after_select(readsetp, writesetp);
1249 }
1250 /* NOTREACHED */
1251 }
1252