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- stevesk@cvs.openbsd.org 2006/07/25 02:59:21
[openssh-git.git] / ssh-agent.c
blobe4b620483ead2e9735c54394e4ed8d39b9f49d25
1 /* $OpenBSD: ssh-agent.c,v 1.147 2006/07/25 02:59:21 stevesk 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/stat.h>
41 #include <sys/socket.h>
42 #ifdef HAVE_SYS_TIME_H
43 # include <sys/time.h>
44 #endif
45 #ifdef HAVE_SYS_UN_H
46 # include <sys/un.h>
47 #endif
48 #include "openbsd-compat/sys-queue.h"
49 #include <sys/resource.h>
50
51 #include <openssl/evp.h>
52 #include <openssl/md5.h>
53
54 #include <errno.h>
55 #include <fcntl.h>
56 #ifdef HAVE_PATHS_H
57 # include <paths.h>
58 #endif
59 #include <signal.h>
60 #include <time.h>
61 #include <string.h>
62 #include <unistd.h>
63
64 #include "ssh.h"
65 #include "rsa.h"
66 #include "buffer.h"
67 #include "bufaux.h"
68 #include "xmalloc.h"
69 #include "key.h"
70 #include "authfd.h"
71 #include "compat.h"
72 #include "log.h"
73 #include "misc.h"
74
75 #ifdef SMARTCARD
76 #include "scard.h"
77 #endif
78
79 #if defined(HAVE_SYS_PRCTL_H)
80 #include <sys/prctl.h> /* For prctl() and PR_SET_DUMPABLE */
81 #endif
82
83 typedef enum {
84 AUTH_UNUSED,
85 AUTH_SOCKET,
86 AUTH_CONNECTION
87 } sock_type;
88
89 typedef struct {
90 int fd;
91 sock_type type;
92 Buffer input;
93 Buffer output;
94 Buffer request;
95 } SocketEntry;
96
97 u_int sockets_alloc = 0;
98 SocketEntry *sockets = NULL;
99
100 typedef struct identity {
101 TAILQ_ENTRY(identity) next;
102 Key *key;
103 char *comment;
104 u_int death;
105 u_int confirm;
106 } Identity;
107
108 typedef struct {
109 int nentries;
110 TAILQ_HEAD(idqueue, identity) idlist;
111 } Idtab;
112
113 /* private key table, one per protocol version */
114 Idtab idtable[3];
115
116 int max_fd = 0;
117
118 /* pid of shell == parent of agent */
119 pid_t parent_pid = -1;
120
121 /* pathname and directory for AUTH_SOCKET */
122 char socket_name[MAXPATHLEN];
123 char socket_dir[MAXPATHLEN];
124
125 /* locking */
126 int locked = 0;
127 char *lock_passwd = NULL;
128
129 extern char *__progname;
130
131 /* Default lifetime (0 == forever) */
132 static int lifetime = 0;
133
134 static void
135 close_socket(SocketEntry *e)
136 {
137 close(e->fd);
138 e->fd = -1;
139 e->type = AUTH_UNUSED;
140 buffer_free(&e->input);
141 buffer_free(&e->output);
142 buffer_free(&e->request);
143 }
144
145 static void
146 idtab_init(void)
147 {
148 int i;
149
150 for (i = 0; i <=2; i++) {
151 TAILQ_INIT(&idtable[i].idlist);
152 idtable[i].nentries = 0;
153 }
154 }
155
156 /* return private key table for requested protocol version */
157 static Idtab *
158 idtab_lookup(int version)
159 {
160 if (version < 1 || version > 2)
161 fatal("internal error, bad protocol version %d", version);
162 return &idtable[version];
163 }
164
165 static void
166 free_identity(Identity *id)
167 {
168 key_free(id->key);
169 xfree(id->comment);
170 xfree(id);
171 }
172
173 /* return matching private key for given public key */
174 static Identity *
175 lookup_identity(Key *key, int version)
176 {
177 Identity *id;
178
179 Idtab *tab = idtab_lookup(version);
180 TAILQ_FOREACH(id, &tab->idlist, next) {
181 if (key_equal(key, id->key))
182 return (id);
183 }
184 return (NULL);
185 }
186
187 /* Check confirmation of keysign request */
188 static int
189 confirm_key(Identity *id)
190 {
191 char *p;
192 int ret = -1;
193
194 p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
195 if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
196 id->comment, p))
197 ret = 0;
198 xfree(p);
199
200 return (ret);
201 }
202
203 /* send list of supported public keys to 'client' */
204 static void
205 process_request_identities(SocketEntry *e, int version)
206 {
207 Idtab *tab = idtab_lookup(version);
208 Identity *id;
209 Buffer msg;
210
211 buffer_init(&msg);
212 buffer_put_char(&msg, (version == 1) ?
213 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
214 buffer_put_int(&msg, tab->nentries);
215 TAILQ_FOREACH(id, &tab->idlist, next) {
216 if (id->key->type == KEY_RSA1) {
217 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
218 buffer_put_bignum(&msg, id->key->rsa->e);
219 buffer_put_bignum(&msg, id->key->rsa->n);
220 } else {
221 u_char *blob;
222 u_int blen;
223 key_to_blob(id->key, &blob, &blen);
224 buffer_put_string(&msg, blob, blen);
225 xfree(blob);
226 }
227 buffer_put_cstring(&msg, id->comment);
228 }
229 buffer_put_int(&e->output, buffer_len(&msg));
230 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
231 buffer_free(&msg);
232 }
233
234 /* ssh1 only */
235 static void
236 process_authentication_challenge1(SocketEntry *e)
237 {
238 u_char buf[32], mdbuf[16], session_id[16];
239 u_int response_type;
240 BIGNUM *challenge;
241 Identity *id;
242 int i, len;
243 Buffer msg;
244 MD5_CTX md;
245 Key *key;
246
247 buffer_init(&msg);
248 key = key_new(KEY_RSA1);
249 if ((challenge = BN_new()) == NULL)
250 fatal("process_authentication_challenge1: BN_new failed");
251
252 (void) buffer_get_int(&e->request); /* ignored */
253 buffer_get_bignum(&e->request, key->rsa->e);
254 buffer_get_bignum(&e->request, key->rsa->n);
255 buffer_get_bignum(&e->request, challenge);
256
257 /* Only protocol 1.1 is supported */
258 if (buffer_len(&e->request) == 0)
259 goto failure;
260 buffer_get(&e->request, session_id, 16);
261 response_type = buffer_get_int(&e->request);
262 if (response_type != 1)
263 goto failure;
264
265 id = lookup_identity(key, 1);
266 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
267 Key *private = id->key;
268 /* Decrypt the challenge using the private key. */
269 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
270 goto failure;
271
272 /* The response is MD5 of decrypted challenge plus session id. */
273 len = BN_num_bytes(challenge);
274 if (len <= 0 || len > 32) {
275 logit("process_authentication_challenge: bad challenge length %d", len);
276 goto failure;
277 }
278 memset(buf, 0, 32);
279 BN_bn2bin(challenge, buf + 32 - len);
280 MD5_Init(&md);
281 MD5_Update(&md, buf, 32);
282 MD5_Update(&md, session_id, 16);
283 MD5_Final(mdbuf, &md);
284
285 /* Send the response. */
286 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
287 for (i = 0; i < 16; i++)
288 buffer_put_char(&msg, mdbuf[i]);
289 goto send;
290 }
291
292 failure:
293 /* Unknown identity or protocol error. Send failure. */
294 buffer_put_char(&msg, SSH_AGENT_FAILURE);
295 send:
296 buffer_put_int(&e->output, buffer_len(&msg));
297 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
298 key_free(key);
299 BN_clear_free(challenge);
300 buffer_free(&msg);
301 }
302
303 /* ssh2 only */
304 static void
305 process_sign_request2(SocketEntry *e)
306 {
307 u_char *blob, *data, *signature = NULL;
308 u_int blen, dlen, slen = 0;
309 extern int datafellows;
310 int ok = -1, flags;
311 Buffer msg;
312 Key *key;
313
314 datafellows = 0;
315
316 blob = buffer_get_string(&e->request, &blen);
317 data = buffer_get_string(&e->request, &dlen);
318
319 flags = buffer_get_int(&e->request);
320 if (flags & SSH_AGENT_OLD_SIGNATURE)
321 datafellows = SSH_BUG_SIGBLOB;
322
323 key = key_from_blob(blob, blen);
324 if (key != NULL) {
325 Identity *id = lookup_identity(key, 2);
326 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
327 ok = key_sign(id->key, &signature, &slen, data, dlen);
328 key_free(key);
329 }
330 buffer_init(&msg);
331 if (ok == 0) {
332 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
333 buffer_put_string(&msg, signature, slen);
334 } else {
335 buffer_put_char(&msg, SSH_AGENT_FAILURE);
336 }
337 buffer_put_int(&e->output, buffer_len(&msg));
338 buffer_append(&e->output, buffer_ptr(&msg),
339 buffer_len(&msg));
340 buffer_free(&msg);
341 xfree(data);
342 xfree(blob);
343 if (signature != NULL)
344 xfree(signature);
345 }
346
347 /* shared */
348 static void
349 process_remove_identity(SocketEntry *e, int version)
350 {
351 u_int blen, bits;
352 int success = 0;
353 Key *key = NULL;
354 u_char *blob;
355
356 switch (version) {
357 case 1:
358 key = key_new(KEY_RSA1);
359 bits = buffer_get_int(&e->request);
360 buffer_get_bignum(&e->request, key->rsa->e);
361 buffer_get_bignum(&e->request, key->rsa->n);
362
363 if (bits != key_size(key))
364 logit("Warning: identity keysize mismatch: actual %u, announced %u",
365 key_size(key), bits);
366 break;
367 case 2:
368 blob = buffer_get_string(&e->request, &blen);
369 key = key_from_blob(blob, blen);
370 xfree(blob);
371 break;
372 }
373 if (key != NULL) {
374 Identity *id = lookup_identity(key, version);
375 if (id != NULL) {
376 /*
377 * We have this key. Free the old key. Since we
378 * don't want to leave empty slots in the middle of
379 * the array, we actually free the key there and move
380 * all the entries between the empty slot and the end
381 * of the array.
382 */
383 Idtab *tab = idtab_lookup(version);
384 if (tab->nentries < 1)
385 fatal("process_remove_identity: "
386 "internal error: tab->nentries %d",
387 tab->nentries);
388 TAILQ_REMOVE(&tab->idlist, id, next);
389 free_identity(id);
390 tab->nentries--;
391 success = 1;
392 }
393 key_free(key);
394 }
395 buffer_put_int(&e->output, 1);
396 buffer_put_char(&e->output,
397 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
398 }
399
400 static void
401 process_remove_all_identities(SocketEntry *e, int version)
402 {
403 Idtab *tab = idtab_lookup(version);
404 Identity *id;
405
406 /* Loop over all identities and clear the keys. */
407 for (id = TAILQ_FIRST(&tab->idlist); id;
408 id = TAILQ_FIRST(&tab->idlist)) {
409 TAILQ_REMOVE(&tab->idlist, id, next);
410 free_identity(id);
411 }
412
413 /* Mark that there are no identities. */
414 tab->nentries = 0;
415
416 /* Send success. */
417 buffer_put_int(&e->output, 1);
418 buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
419 }
420
421 static void
422 reaper(void)
423 {
424 u_int now = time(NULL);
425 Identity *id, *nxt;
426 int version;
427 Idtab *tab;
428
429 for (version = 1; version < 3; version++) {
430 tab = idtab_lookup(version);
431 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
432 nxt = TAILQ_NEXT(id, next);
433 if (id->death != 0 && now >= id->death) {
434 TAILQ_REMOVE(&tab->idlist, id, next);
435 free_identity(id);
436 tab->nentries--;
437 }
438 }
439 }
440 }
441
442 static void
443 process_add_identity(SocketEntry *e, int version)
444 {
445 Idtab *tab = idtab_lookup(version);
446 int type, success = 0, death = 0, confirm = 0;
447 char *type_name, *comment;
448 Key *k = NULL;
449
450 switch (version) {
451 case 1:
452 k = key_new_private(KEY_RSA1);
453 (void) buffer_get_int(&e->request); /* ignored */
454 buffer_get_bignum(&e->request, k->rsa->n);
455 buffer_get_bignum(&e->request, k->rsa->e);
456 buffer_get_bignum(&e->request, k->rsa->d);
457 buffer_get_bignum(&e->request, k->rsa->iqmp);
458
459 /* SSH and SSL have p and q swapped */
460 buffer_get_bignum(&e->request, k->rsa->q); /* p */
461 buffer_get_bignum(&e->request, k->rsa->p); /* q */
462
463 /* Generate additional parameters */
464 rsa_generate_additional_parameters(k->rsa);
465 break;
466 case 2:
467 type_name = buffer_get_string(&e->request, NULL);
468 type = key_type_from_name(type_name);
469 xfree(type_name);
470 switch (type) {
471 case KEY_DSA:
472 k = key_new_private(type);
473 buffer_get_bignum2(&e->request, k->dsa->p);
474 buffer_get_bignum2(&e->request, k->dsa->q);
475 buffer_get_bignum2(&e->request, k->dsa->g);
476 buffer_get_bignum2(&e->request, k->dsa->pub_key);
477 buffer_get_bignum2(&e->request, k->dsa->priv_key);
478 break;
479 case KEY_RSA:
480 k = key_new_private(type);
481 buffer_get_bignum2(&e->request, k->rsa->n);
482 buffer_get_bignum2(&e->request, k->rsa->e);
483 buffer_get_bignum2(&e->request, k->rsa->d);
484 buffer_get_bignum2(&e->request, k->rsa->iqmp);
485 buffer_get_bignum2(&e->request, k->rsa->p);
486 buffer_get_bignum2(&e->request, k->rsa->q);
487
488 /* Generate additional parameters */
489 rsa_generate_additional_parameters(k->rsa);
490 break;
491 default:
492 buffer_clear(&e->request);
493 goto send;
494 }
495 break;
496 }
497 /* enable blinding */
498 switch (k->type) {
499 case KEY_RSA:
500 case KEY_RSA1:
501 if (RSA_blinding_on(k->rsa, NULL) != 1) {
502 error("process_add_identity: RSA_blinding_on failed");
503 key_free(k);
504 goto send;
505 }
506 break;
507 }
508 comment = buffer_get_string(&e->request, NULL);
509 if (k == NULL) {
510 xfree(comment);
511 goto send;
512 }
513 success = 1;
514 while (buffer_len(&e->request)) {
515 switch (buffer_get_char(&e->request)) {
516 case SSH_AGENT_CONSTRAIN_LIFETIME:
517 death = time(NULL) + buffer_get_int(&e->request);
518 break;
519 case SSH_AGENT_CONSTRAIN_CONFIRM:
520 confirm = 1;
521 break;
522 default:
523 break;
524 }
525 }
526 if (lifetime && !death)
527 death = time(NULL) + lifetime;
528 if (lookup_identity(k, version) == NULL) {
529 Identity *id = xmalloc(sizeof(Identity));
530 id->key = k;
531 id->comment = comment;
532 id->death = death;
533 id->confirm = confirm;
534 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
535 /* Increment the number of identities. */
536 tab->nentries++;
537 } else {
538 key_free(k);
539 xfree(comment);
540 }
541 send:
542 buffer_put_int(&e->output, 1);
543 buffer_put_char(&e->output,
544 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
545 }
546
547 /* XXX todo: encrypt sensitive data with passphrase */
548 static void
549 process_lock_agent(SocketEntry *e, int lock)
550 {
551 int success = 0;
552 char *passwd;
553
554 passwd = buffer_get_string(&e->request, NULL);
555 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
556 locked = 0;
557 memset(lock_passwd, 0, strlen(lock_passwd));
558 xfree(lock_passwd);
559 lock_passwd = NULL;
560 success = 1;
561 } else if (!locked && lock) {
562 locked = 1;
563 lock_passwd = xstrdup(passwd);
564 success = 1;
565 }
566 memset(passwd, 0, strlen(passwd));
567 xfree(passwd);
568
569 buffer_put_int(&e->output, 1);
570 buffer_put_char(&e->output,
571 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
572 }
573
574 static void
575 no_identities(SocketEntry *e, u_int type)
576 {
577 Buffer msg;
578
579 buffer_init(&msg);
580 buffer_put_char(&msg,
581 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
582 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
583 buffer_put_int(&msg, 0);
584 buffer_put_int(&e->output, buffer_len(&msg));
585 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
586 buffer_free(&msg);
587 }
588
589 #ifdef SMARTCARD
590 static void
591 process_add_smartcard_key (SocketEntry *e)
592 {
593 char *sc_reader_id = NULL, *pin;
594 int i, version, success = 0, death = 0, confirm = 0;
595 Key **keys, *k;
596 Identity *id;
597 Idtab *tab;
598
599 sc_reader_id = buffer_get_string(&e->request, NULL);
600 pin = buffer_get_string(&e->request, NULL);
601
602 while (buffer_len(&e->request)) {
603 switch (buffer_get_char(&e->request)) {
604 case SSH_AGENT_CONSTRAIN_LIFETIME:
605 death = time(NULL) + buffer_get_int(&e->request);
606 break;
607 case SSH_AGENT_CONSTRAIN_CONFIRM:
608 confirm = 1;
609 break;
610 default:
611 break;
612 }
613 }
614 if (lifetime && !death)
615 death = time(NULL) + lifetime;
616
617 keys = sc_get_keys(sc_reader_id, pin);
618 xfree(sc_reader_id);
619 xfree(pin);
620
621 if (keys == NULL || keys[0] == NULL) {
622 error("sc_get_keys failed");
623 goto send;
624 }
625 for (i = 0; keys[i] != NULL; i++) {
626 k = keys[i];
627 version = k->type == KEY_RSA1 ? 1 : 2;
628 tab = idtab_lookup(version);
629 if (lookup_identity(k, version) == NULL) {
630 id = xmalloc(sizeof(Identity));
631 id->key = k;
632 id->comment = sc_get_key_label(k);
633 id->death = death;
634 id->confirm = confirm;
635 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
636 tab->nentries++;
637 success = 1;
638 } else {
639 key_free(k);
640 }
641 keys[i] = NULL;
642 }
643 xfree(keys);
644 send:
645 buffer_put_int(&e->output, 1);
646 buffer_put_char(&e->output,
647 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
648 }
649
650 static void
651 process_remove_smartcard_key(SocketEntry *e)
652 {
653 char *sc_reader_id = NULL, *pin;
654 int i, version, success = 0;
655 Key **keys, *k = NULL;
656 Identity *id;
657 Idtab *tab;
658
659 sc_reader_id = buffer_get_string(&e->request, NULL);
660 pin = buffer_get_string(&e->request, NULL);
661 keys = sc_get_keys(sc_reader_id, pin);
662 xfree(sc_reader_id);
663 xfree(pin);
664
665 if (keys == NULL || keys[0] == NULL) {
666 error("sc_get_keys failed");
667 goto send;
668 }
669 for (i = 0; keys[i] != NULL; i++) {
670 k = keys[i];
671 version = k->type == KEY_RSA1 ? 1 : 2;
672 if ((id = lookup_identity(k, version)) != NULL) {
673 tab = idtab_lookup(version);
674 TAILQ_REMOVE(&tab->idlist, id, next);
675 tab->nentries--;
676 free_identity(id);
677 success = 1;
678 }
679 key_free(k);
680 keys[i] = NULL;
681 }
682 xfree(keys);
683 send:
684 buffer_put_int(&e->output, 1);
685 buffer_put_char(&e->output,
686 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
687 }
688 #endif /* SMARTCARD */
689
690 /* dispatch incoming messages */
691
692 static void
693 process_message(SocketEntry *e)
694 {
695 u_int msg_len, type;
696 u_char *cp;
697
698 /* kill dead keys */
699 reaper();
700
701 if (buffer_len(&e->input) < 5)
702 return; /* Incomplete message. */
703 cp = buffer_ptr(&e->input);
704 msg_len = get_u32(cp);
705 if (msg_len > 256 * 1024) {
706 close_socket(e);
707 return;
708 }
709 if (buffer_len(&e->input) < msg_len + 4)
710 return;
711
712 /* move the current input to e->request */
713 buffer_consume(&e->input, 4);
714 buffer_clear(&e->request);
715 buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
716 buffer_consume(&e->input, msg_len);
717 type = buffer_get_char(&e->request);
718
719 /* check wheter agent is locked */
720 if (locked && type != SSH_AGENTC_UNLOCK) {
721 buffer_clear(&e->request);
722 switch (type) {
723 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
724 case SSH2_AGENTC_REQUEST_IDENTITIES:
725 /* send empty lists */
726 no_identities(e, type);
727 break;
728 default:
729 /* send a fail message for all other request types */
730 buffer_put_int(&e->output, 1);
731 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
732 }
733 return;
734 }
735
736 debug("type %d", type);
737 switch (type) {
738 case SSH_AGENTC_LOCK:
739 case SSH_AGENTC_UNLOCK:
740 process_lock_agent(e, type == SSH_AGENTC_LOCK);
741 break;
742 /* ssh1 */
743 case SSH_AGENTC_RSA_CHALLENGE:
744 process_authentication_challenge1(e);
745 break;
746 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
747 process_request_identities(e, 1);
748 break;
749 case SSH_AGENTC_ADD_RSA_IDENTITY:
750 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
751 process_add_identity(e, 1);
752 break;
753 case SSH_AGENTC_REMOVE_RSA_IDENTITY:
754 process_remove_identity(e, 1);
755 break;
756 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
757 process_remove_all_identities(e, 1);
758 break;
759 /* ssh2 */
760 case SSH2_AGENTC_SIGN_REQUEST:
761 process_sign_request2(e);
762 break;
763 case SSH2_AGENTC_REQUEST_IDENTITIES:
764 process_request_identities(e, 2);
765 break;
766 case SSH2_AGENTC_ADD_IDENTITY:
767 case SSH2_AGENTC_ADD_ID_CONSTRAINED:
768 process_add_identity(e, 2);
769 break;
770 case SSH2_AGENTC_REMOVE_IDENTITY:
771 process_remove_identity(e, 2);
772 break;
773 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
774 process_remove_all_identities(e, 2);
775 break;
776 #ifdef SMARTCARD
777 case SSH_AGENTC_ADD_SMARTCARD_KEY:
778 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
779 process_add_smartcard_key(e);
780 break;
781 case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
782 process_remove_smartcard_key(e);
783 break;
784 #endif /* SMARTCARD */
785 default:
786 /* Unknown message. Respond with failure. */
787 error("Unknown message %d", type);
788 buffer_clear(&e->request);
789 buffer_put_int(&e->output, 1);
790 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
791 break;
792 }
793 }
794
795 static void
796 new_socket(sock_type type, int fd)
797 {
798 u_int i, old_alloc, new_alloc;
799
800 set_nonblock(fd);
801
802 if (fd > max_fd)
803 max_fd = fd;
804
805 for (i = 0; i < sockets_alloc; i++)
806 if (sockets[i].type == AUTH_UNUSED) {
807 sockets[i].fd = fd;
808 buffer_init(&sockets[i].input);
809 buffer_init(&sockets[i].output);
810 buffer_init(&sockets[i].request);
811 sockets[i].type = type;
812 return;
813 }
814 old_alloc = sockets_alloc;
815 new_alloc = sockets_alloc + 10;
816 sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
817 for (i = old_alloc; i < new_alloc; i++)
818 sockets[i].type = AUTH_UNUSED;
819 sockets_alloc = new_alloc;
820 sockets[old_alloc].fd = fd;
821 buffer_init(&sockets[old_alloc].input);
822 buffer_init(&sockets[old_alloc].output);
823 buffer_init(&sockets[old_alloc].request);
824 sockets[old_alloc].type = type;
825 }
826
827 static int
828 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
829 {
830 u_int i, sz;
831 int n = 0;
832
833 for (i = 0; i < sockets_alloc; i++) {
834 switch (sockets[i].type) {
835 case AUTH_SOCKET:
836 case AUTH_CONNECTION:
837 n = MAX(n, sockets[i].fd);
838 break;
839 case AUTH_UNUSED:
840 break;
841 default:
842 fatal("Unknown socket type %d", sockets[i].type);
843 break;
844 }
845 }
846
847 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
848 if (*fdrp == NULL || sz > *nallocp) {
849 if (*fdrp)
850 xfree(*fdrp);
851 if (*fdwp)
852 xfree(*fdwp);
853 *fdrp = xmalloc(sz);
854 *fdwp = xmalloc(sz);
855 *nallocp = sz;
856 }
857 if (n < *fdl)
858 debug("XXX shrink: %d < %d", n, *fdl);
859 *fdl = n;
860 memset(*fdrp, 0, sz);
861 memset(*fdwp, 0, sz);
862
863 for (i = 0; i < sockets_alloc; i++) {
864 switch (sockets[i].type) {
865 case AUTH_SOCKET:
866 case AUTH_CONNECTION:
867 FD_SET(sockets[i].fd, *fdrp);
868 if (buffer_len(&sockets[i].output) > 0)
869 FD_SET(sockets[i].fd, *fdwp);
870 break;
871 default:
872 break;
873 }
874 }
875 return (1);
876 }
877
878 static void
879 after_select(fd_set *readset, fd_set *writeset)
880 {
881 struct sockaddr_un sunaddr;
882 socklen_t slen;
883 char buf[1024];
884 int len, sock;
885 u_int i;
886 uid_t euid;
887 gid_t egid;
888
889 for (i = 0; i < sockets_alloc; i++)
890 switch (sockets[i].type) {
891 case AUTH_UNUSED:
892 break;
893 case AUTH_SOCKET:
894 if (FD_ISSET(sockets[i].fd, readset)) {
895 slen = sizeof(sunaddr);
896 sock = accept(sockets[i].fd,
897 (struct sockaddr *)&sunaddr, &slen);
898 if (sock < 0) {
899 error("accept from AUTH_SOCKET: %s",
900 strerror(errno));
901 break;
902 }
903 if (getpeereid(sock, &euid, &egid) < 0) {
904 error("getpeereid %d failed: %s",
905 sock, strerror(errno));
906 close(sock);
907 break;
908 }
909 if ((euid != 0) && (getuid() != euid)) {
910 error("uid mismatch: "
911 "peer euid %u != uid %u",
912 (u_int) euid, (u_int) getuid());
913 close(sock);
914 break;
915 }
916 new_socket(AUTH_CONNECTION, sock);
917 }
918 break;
919 case AUTH_CONNECTION:
920 if (buffer_len(&sockets[i].output) > 0 &&
921 FD_ISSET(sockets[i].fd, writeset)) {
922 do {
923 len = write(sockets[i].fd,
924 buffer_ptr(&sockets[i].output),
925 buffer_len(&sockets[i].output));
926 if (len == -1 && (errno == EAGAIN ||
927 errno == EINTR))
928 continue;
929 break;
930 } while (1);
931 if (len <= 0) {
932 close_socket(&sockets[i]);
933 break;
934 }
935 buffer_consume(&sockets[i].output, len);
936 }
937 if (FD_ISSET(sockets[i].fd, readset)) {
938 do {
939 len = read(sockets[i].fd, buf, sizeof(buf));
940 if (len == -1 && (errno == EAGAIN ||
941 errno == EINTR))
942 continue;
943 break;
944 } while (1);
945 if (len <= 0) {
946 close_socket(&sockets[i]);
947 break;
948 }
949 buffer_append(&sockets[i].input, buf, len);
950 process_message(&sockets[i]);
951 }
952 break;
953 default:
954 fatal("Unknown type %d", sockets[i].type);
955 }
956 }
957
958 static void
959 cleanup_socket(void)
960 {
961 if (socket_name[0])
962 unlink(socket_name);
963 if (socket_dir[0])
964 rmdir(socket_dir);
965 }
966
967 void
968 cleanup_exit(int i)
969 {
970 cleanup_socket();
971 _exit(i);
972 }
973
974 /*ARGSUSED*/
975 static void
976 cleanup_handler(int sig)
977 {
978 cleanup_socket();
979 _exit(2);
980 }
981
982 /*ARGSUSED*/
983 static void
984 check_parent_exists(int sig)
985 {
986 int save_errno = errno;
987
988 if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
989 /* printf("Parent has died - Authentication agent exiting.\n"); */
990 cleanup_handler(sig); /* safe */
991 }
992 mysignal(SIGALRM, check_parent_exists);
993 alarm(10);
994 errno = save_errno;
995 }
996
997 static void
998 usage(void)
999 {
1000 fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
1001 __progname);
1002 fprintf(stderr, "Options:\n");
1003 fprintf(stderr, " -c Generate C-shell commands on stdout.\n");
1004 fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n");
1005 fprintf(stderr, " -k Kill the current agent.\n");
1006 fprintf(stderr, " -d Debug mode.\n");
1007 fprintf(stderr, " -a socket Bind agent socket to given name.\n");
1008 fprintf(stderr, " -t life Default identity lifetime (seconds).\n");
1009 exit(1);
1010 }
1011
1012 int
1013 main(int ac, char **av)
1014 {
1015 int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1016 int sock, fd, ch;
1017 u_int nalloc;
1018 char *shell, *format, *pidstr, *agentsocket = NULL;
1019 fd_set *readsetp = NULL, *writesetp = NULL;
1020 struct sockaddr_un sunaddr;
1021 #ifdef HAVE_SETRLIMIT
1022 struct rlimit rlim;
1023 #endif
1024 int prev_mask;
1025 extern int optind;
1026 extern char *optarg;
1027 pid_t pid;
1028 char pidstrbuf[1 + 3 * sizeof pid];
1029
1030 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1031 sanitise_stdfd();
1032
1033 /* drop */
1034 setegid(getgid());
1035 setgid(getgid());
1036
1037 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1038 /* Disable ptrace on Linux without sgid bit */
1039 prctl(PR_SET_DUMPABLE, 0);
1040 #endif
1041
1042 SSLeay_add_all_algorithms();
1043
1044 __progname = ssh_get_progname(av[0]);
1045 init_rng();
1046 seed_rng();
1047
1048 while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1049 switch (ch) {
1050 case 'c':
1051 if (s_flag)
1052 usage();
1053 c_flag++;
1054 break;
1055 case 'k':
1056 k_flag++;
1057 break;
1058 case 's':
1059 if (c_flag)
1060 usage();
1061 s_flag++;
1062 break;
1063 case 'd':
1064 if (d_flag)
1065 usage();
1066 d_flag++;
1067 break;
1068 case 'a':
1069 agentsocket = optarg;
1070 break;
1071 case 't':
1072 if ((lifetime = convtime(optarg)) == -1) {
1073 fprintf(stderr, "Invalid lifetime\n");
1074 usage();
1075 }
1076 break;
1077 default:
1078 usage();
1079 }
1080 }
1081 ac -= optind;
1082 av += optind;
1083
1084 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1085 usage();
1086
1087 if (ac == 0 && !c_flag && !s_flag) {
1088 shell = getenv("SHELL");
1089 if (shell != NULL &&
1090 strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1091 c_flag = 1;
1092 }
1093 if (k_flag) {
1094 const char *errstr = NULL;
1095
1096 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1097 if (pidstr == NULL) {
1098 fprintf(stderr, "%s not set, cannot kill agent\n",
1099 SSH_AGENTPID_ENV_NAME);
1100 exit(1);
1101 }
1102 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1103 if (errstr) {
1104 fprintf(stderr,
1105 "%s=\"%s\", which is not a good PID: %s\n",
1106 SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1107 exit(1);
1108 }
1109 if (kill(pid, SIGTERM) == -1) {
1110 perror("kill");
1111 exit(1);
1112 }
1113 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1114 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1115 printf(format, SSH_AGENTPID_ENV_NAME);
1116 printf("echo Agent pid %ld killed;\n", (long)pid);
1117 exit(0);
1118 }
1119 parent_pid = getpid();
1120
1121 if (agentsocket == NULL) {
1122 /* Create private directory for agent socket */
1123 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1124 if (mkdtemp(socket_dir) == NULL) {
1125 perror("mkdtemp: private socket dir");
1126 exit(1);
1127 }
1128 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1129 (long)parent_pid);
1130 } else {
1131 /* Try to use specified agent socket */
1132 socket_dir[0] = '\0';
1133 strlcpy(socket_name, agentsocket, sizeof socket_name);
1134 }
1135
1136 /*
1137 * Create socket early so it will exist before command gets run from
1138 * the parent.
1139 */
1140 sock = socket(AF_UNIX, SOCK_STREAM, 0);
1141 if (sock < 0) {
1142 perror("socket");
1143 *socket_name = '\0'; /* Don't unlink any existing file */
1144 cleanup_exit(1);
1145 }
1146 memset(&sunaddr, 0, sizeof(sunaddr));
1147 sunaddr.sun_family = AF_UNIX;
1148 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1149 prev_mask = umask(0177);
1150 if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1151 perror("bind");
1152 *socket_name = '\0'; /* Don't unlink any existing file */
1153 umask(prev_mask);
1154 cleanup_exit(1);
1155 }
1156 umask(prev_mask);
1157 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1158 perror("listen");
1159 cleanup_exit(1);
1160 }
1161
1162 /*
1163 * Fork, and have the parent execute the command, if any, or present
1164 * the socket data. The child continues as the authentication agent.
1165 */
1166 if (d_flag) {
1167 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1168 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1169 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1170 SSH_AUTHSOCKET_ENV_NAME);
1171 printf("echo Agent pid %ld;\n", (long)parent_pid);
1172 goto skip;
1173 }
1174 pid = fork();
1175 if (pid == -1) {
1176 perror("fork");
1177 cleanup_exit(1);
1178 }
1179 if (pid != 0) { /* Parent - execute the given command. */
1180 close(sock);
1181 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1182 if (ac == 0) {
1183 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1184 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1185 SSH_AUTHSOCKET_ENV_NAME);
1186 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1187 SSH_AGENTPID_ENV_NAME);
1188 printf("echo Agent pid %ld;\n", (long)pid);
1189 exit(0);
1190 }
1191 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1192 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1193 perror("setenv");
1194 exit(1);
1195 }
1196 execvp(av[0], av);
1197 perror(av[0]);
1198 exit(1);
1199 }
1200 /* child */
1201 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1202
1203 if (setsid() == -1) {
1204 error("setsid: %s", strerror(errno));
1205 cleanup_exit(1);
1206 }
1207
1208 (void)chdir("/");
1209 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1210 /* XXX might close listen socket */
1211 (void)dup2(fd, STDIN_FILENO);
1212 (void)dup2(fd, STDOUT_FILENO);
1213 (void)dup2(fd, STDERR_FILENO);
1214 if (fd > 2)
1215 close(fd);
1216 }
1217
1218 #ifdef HAVE_SETRLIMIT
1219 /* deny core dumps, since memory contains unencrypted private keys */
1220 rlim.rlim_cur = rlim.rlim_max = 0;
1221 if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1222 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1223 cleanup_exit(1);
1224 }
1225 #endif
1226
1227 skip:
1228 new_socket(AUTH_SOCKET, sock);
1229 if (ac > 0) {
1230 mysignal(SIGALRM, check_parent_exists);
1231 alarm(10);
1232 }
1233 idtab_init();
1234 if (!d_flag)
1235 signal(SIGINT, SIG_IGN);
1236 signal(SIGPIPE, SIG_IGN);
1237 signal(SIGHUP, cleanup_handler);
1238 signal(SIGTERM, cleanup_handler);
1239 nalloc = 0;
1240
1241 while (1) {
1242 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1243 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1244 if (errno == EINTR)
1245 continue;
1246 fatal("select: %s", strerror(errno));
1247 }
1248 after_select(readsetp, writesetp);
1249 }
1250 /* NOTREACHED */
1251 }
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