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- (djm) [auth-pam.c auth-shadow.c auth2-none.c cleanup.c sshd.c]
[openssh-git.git] / ssh-agent.c
blob6bc1e541ae9f1f145d34b7f4a24f3167acfff429
1 /* $OpenBSD: ssh-agent.c,v 1.152 2006/08/04 20:46:05 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/param.h>
41 #include <sys/resource.h>
42 #include <sys/stat.h>
43 #include <sys/socket.h>
44 #ifdef HAVE_SYS_TIME_H
45 # include <sys/time.h>
46 #endif
47 #ifdef HAVE_SYS_UN_H
48 # include <sys/un.h>
49 #endif
50 #include "openbsd-compat/sys-queue.h"
51
52 #include <openssl/evp.h>
53 #include <openssl/md5.h>
54
55 #include <errno.h>
56 #include <fcntl.h>
57 #ifdef HAVE_PATHS_H
58 # include <paths.h>
59 #endif
60 #include <signal.h>
61 #include <stdio.h>
62 #include <stdlib.h>
63 #include <time.h>
64 #include <string.h>
65 #include <unistd.h>
66
67 #include "xmalloc.h"
68 #include "ssh.h"
69 #include "rsa.h"
70 #include "buffer.h"
71 #include "key.h"
72 #include "authfd.h"
73 #include "compat.h"
74 #include "log.h"
75 #include "misc.h"
76
77 #ifdef SMARTCARD
78 #include "scard.h"
79 #endif
80
81 #if defined(HAVE_SYS_PRCTL_H)
82 #include <sys/prctl.h> /* For prctl() and PR_SET_DUMPABLE */
83 #endif
84
85 typedef enum {
86 AUTH_UNUSED,
87 AUTH_SOCKET,
88 AUTH_CONNECTION
89 } sock_type;
90
91 typedef struct {
92 int fd;
93 sock_type type;
94 Buffer input;
95 Buffer output;
96 Buffer request;
97 } SocketEntry;
98
99 u_int sockets_alloc = 0;
100 SocketEntry *sockets = NULL;
101
102 typedef struct identity {
103 TAILQ_ENTRY(identity) next;
104 Key *key;
105 char *comment;
106 u_int death;
107 u_int confirm;
108 } Identity;
109
110 typedef struct {
111 int nentries;
112 TAILQ_HEAD(idqueue, identity) idlist;
113 } Idtab;
114
115 /* private key table, one per protocol version */
116 Idtab idtable[3];
117
118 int max_fd = 0;
119
120 /* pid of shell == parent of agent */
121 pid_t parent_pid = -1;
122
123 /* pathname and directory for AUTH_SOCKET */
124 char socket_name[MAXPATHLEN];
125 char socket_dir[MAXPATHLEN];
126
127 /* locking */
128 int locked = 0;
129 char *lock_passwd = NULL;
130
131 extern char *__progname;
132
133 /* Default lifetime (0 == forever) */
134 static int lifetime = 0;
135
136 static void
137 close_socket(SocketEntry *e)
138 {
139 close(e->fd);
140 e->fd = -1;
141 e->type = AUTH_UNUSED;
142 buffer_free(&e->input);
143 buffer_free(&e->output);
144 buffer_free(&e->request);
145 }
146
147 static void
148 idtab_init(void)
149 {
150 int i;
151
152 for (i = 0; i <=2; i++) {
153 TAILQ_INIT(&idtable[i].idlist);
154 idtable[i].nentries = 0;
155 }
156 }
157
158 /* return private key table for requested protocol version */
159 static Idtab *
160 idtab_lookup(int version)
161 {
162 if (version < 1 || version > 2)
163 fatal("internal error, bad protocol version %d", version);
164 return &idtable[version];
165 }
166
167 static void
168 free_identity(Identity *id)
169 {
170 key_free(id->key);
171 xfree(id->comment);
172 xfree(id);
173 }
174
175 /* return matching private key for given public key */
176 static Identity *
177 lookup_identity(Key *key, int version)
178 {
179 Identity *id;
180
181 Idtab *tab = idtab_lookup(version);
182 TAILQ_FOREACH(id, &tab->idlist, next) {
183 if (key_equal(key, id->key))
184 return (id);
185 }
186 return (NULL);
187 }
188
189 /* Check confirmation of keysign request */
190 static int
191 confirm_key(Identity *id)
192 {
193 char *p;
194 int ret = -1;
195
196 p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
197 if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
198 id->comment, p))
199 ret = 0;
200 xfree(p);
201
202 return (ret);
203 }
204
205 /* send list of supported public keys to 'client' */
206 static void
207 process_request_identities(SocketEntry *e, int version)
208 {
209 Idtab *tab = idtab_lookup(version);
210 Identity *id;
211 Buffer msg;
212
213 buffer_init(&msg);
214 buffer_put_char(&msg, (version == 1) ?
215 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
216 buffer_put_int(&msg, tab->nentries);
217 TAILQ_FOREACH(id, &tab->idlist, next) {
218 if (id->key->type == KEY_RSA1) {
219 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
220 buffer_put_bignum(&msg, id->key->rsa->e);
221 buffer_put_bignum(&msg, id->key->rsa->n);
222 } else {
223 u_char *blob;
224 u_int blen;
225 key_to_blob(id->key, &blob, &blen);
226 buffer_put_string(&msg, blob, blen);
227 xfree(blob);
228 }
229 buffer_put_cstring(&msg, id->comment);
230 }
231 buffer_put_int(&e->output, buffer_len(&msg));
232 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
233 buffer_free(&msg);
234 }
235
236 /* ssh1 only */
237 static void
238 process_authentication_challenge1(SocketEntry *e)
239 {
240 u_char buf[32], mdbuf[16], session_id[16];
241 u_int response_type;
242 BIGNUM *challenge;
243 Identity *id;
244 int i, len;
245 Buffer msg;
246 MD5_CTX md;
247 Key *key;
248
249 buffer_init(&msg);
250 key = key_new(KEY_RSA1);
251 if ((challenge = BN_new()) == NULL)
252 fatal("process_authentication_challenge1: BN_new failed");
253
254 (void) buffer_get_int(&e->request); /* ignored */
255 buffer_get_bignum(&e->request, key->rsa->e);
256 buffer_get_bignum(&e->request, key->rsa->n);
257 buffer_get_bignum(&e->request, challenge);
258
259 /* Only protocol 1.1 is supported */
260 if (buffer_len(&e->request) == 0)
261 goto failure;
262 buffer_get(&e->request, session_id, 16);
263 response_type = buffer_get_int(&e->request);
264 if (response_type != 1)
265 goto failure;
266
267 id = lookup_identity(key, 1);
268 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
269 Key *private = id->key;
270 /* Decrypt the challenge using the private key. */
271 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
272 goto failure;
273
274 /* The response is MD5 of decrypted challenge plus session id. */
275 len = BN_num_bytes(challenge);
276 if (len <= 0 || len > 32) {
277 logit("process_authentication_challenge: bad challenge length %d", len);
278 goto failure;
279 }
280 memset(buf, 0, 32);
281 BN_bn2bin(challenge, buf + 32 - len);
282 MD5_Init(&md);
283 MD5_Update(&md, buf, 32);
284 MD5_Update(&md, session_id, 16);
285 MD5_Final(mdbuf, &md);
286
287 /* Send the response. */
288 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
289 for (i = 0; i < 16; i++)
290 buffer_put_char(&msg, mdbuf[i]);
291 goto send;
292 }
293
294 failure:
295 /* Unknown identity or protocol error. Send failure. */
296 buffer_put_char(&msg, SSH_AGENT_FAILURE);
297 send:
298 buffer_put_int(&e->output, buffer_len(&msg));
299 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
300 key_free(key);
301 BN_clear_free(challenge);
302 buffer_free(&msg);
303 }
304
305 /* ssh2 only */
306 static void
307 process_sign_request2(SocketEntry *e)
308 {
309 u_char *blob, *data, *signature = NULL;
310 u_int blen, dlen, slen = 0;
311 extern int datafellows;
312 int ok = -1, flags;
313 Buffer msg;
314 Key *key;
315
316 datafellows = 0;
317
318 blob = buffer_get_string(&e->request, &blen);
319 data = buffer_get_string(&e->request, &dlen);
320
321 flags = buffer_get_int(&e->request);
322 if (flags & SSH_AGENT_OLD_SIGNATURE)
323 datafellows = SSH_BUG_SIGBLOB;
324
325 key = key_from_blob(blob, blen);
326 if (key != NULL) {
327 Identity *id = lookup_identity(key, 2);
328 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
329 ok = key_sign(id->key, &signature, &slen, data, dlen);
330 key_free(key);
331 }
332 buffer_init(&msg);
333 if (ok == 0) {
334 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
335 buffer_put_string(&msg, signature, slen);
336 } else {
337 buffer_put_char(&msg, SSH_AGENT_FAILURE);
338 }
339 buffer_put_int(&e->output, buffer_len(&msg));
340 buffer_append(&e->output, buffer_ptr(&msg),
341 buffer_len(&msg));
342 buffer_free(&msg);
343 xfree(data);
344 xfree(blob);
345 if (signature != NULL)
346 xfree(signature);
347 }
348
349 /* shared */
350 static void
351 process_remove_identity(SocketEntry *e, int version)
352 {
353 u_int blen, bits;
354 int success = 0;
355 Key *key = NULL;
356 u_char *blob;
357
358 switch (version) {
359 case 1:
360 key = key_new(KEY_RSA1);
361 bits = buffer_get_int(&e->request);
362 buffer_get_bignum(&e->request, key->rsa->e);
363 buffer_get_bignum(&e->request, key->rsa->n);
364
365 if (bits != key_size(key))
366 logit("Warning: identity keysize mismatch: actual %u, announced %u",
367 key_size(key), bits);
368 break;
369 case 2:
370 blob = buffer_get_string(&e->request, &blen);
371 key = key_from_blob(blob, blen);
372 xfree(blob);
373 break;
374 }
375 if (key != NULL) {
376 Identity *id = lookup_identity(key, version);
377 if (id != NULL) {
378 /*
379 * We have this key. Free the old key. Since we
380 * don't want to leave empty slots in the middle of
381 * the array, we actually free the key there and move
382 * all the entries between the empty slot and the end
383 * of the array.
384 */
385 Idtab *tab = idtab_lookup(version);
386 if (tab->nentries < 1)
387 fatal("process_remove_identity: "
388 "internal error: tab->nentries %d",
389 tab->nentries);
390 TAILQ_REMOVE(&tab->idlist, id, next);
391 free_identity(id);
392 tab->nentries--;
393 success = 1;
394 }
395 key_free(key);
396 }
397 buffer_put_int(&e->output, 1);
398 buffer_put_char(&e->output,
399 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
400 }
401
402 static void
403 process_remove_all_identities(SocketEntry *e, int version)
404 {
405 Idtab *tab = idtab_lookup(version);
406 Identity *id;
407
408 /* Loop over all identities and clear the keys. */
409 for (id = TAILQ_FIRST(&tab->idlist); id;
410 id = TAILQ_FIRST(&tab->idlist)) {
411 TAILQ_REMOVE(&tab->idlist, id, next);
412 free_identity(id);
413 }
414
415 /* Mark that there are no identities. */
416 tab->nentries = 0;
417
418 /* Send success. */
419 buffer_put_int(&e->output, 1);
420 buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
421 }
422
423 static void
424 reaper(void)
425 {
426 u_int now = time(NULL);
427 Identity *id, *nxt;
428 int version;
429 Idtab *tab;
430
431 for (version = 1; version < 3; version++) {
432 tab = idtab_lookup(version);
433 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
434 nxt = TAILQ_NEXT(id, next);
435 if (id->death != 0 && now >= id->death) {
436 TAILQ_REMOVE(&tab->idlist, id, next);
437 free_identity(id);
438 tab->nentries--;
439 }
440 }
441 }
442 }
443
444 static void
445 process_add_identity(SocketEntry *e, int version)
446 {
447 Idtab *tab = idtab_lookup(version);
448 int type, success = 0, death = 0, confirm = 0;
449 char *type_name, *comment;
450 Key *k = NULL;
451
452 switch (version) {
453 case 1:
454 k = key_new_private(KEY_RSA1);
455 (void) buffer_get_int(&e->request); /* ignored */
456 buffer_get_bignum(&e->request, k->rsa->n);
457 buffer_get_bignum(&e->request, k->rsa->e);
458 buffer_get_bignum(&e->request, k->rsa->d);
459 buffer_get_bignum(&e->request, k->rsa->iqmp);
460
461 /* SSH and SSL have p and q swapped */
462 buffer_get_bignum(&e->request, k->rsa->q); /* p */
463 buffer_get_bignum(&e->request, k->rsa->p); /* q */
464
465 /* Generate additional parameters */
466 rsa_generate_additional_parameters(k->rsa);
467 break;
468 case 2:
469 type_name = buffer_get_string(&e->request, NULL);
470 type = key_type_from_name(type_name);
471 xfree(type_name);
472 switch (type) {
473 case KEY_DSA:
474 k = key_new_private(type);
475 buffer_get_bignum2(&e->request, k->dsa->p);
476 buffer_get_bignum2(&e->request, k->dsa->q);
477 buffer_get_bignum2(&e->request, k->dsa->g);
478 buffer_get_bignum2(&e->request, k->dsa->pub_key);
479 buffer_get_bignum2(&e->request, k->dsa->priv_key);
480 break;
481 case KEY_RSA:
482 k = key_new_private(type);
483 buffer_get_bignum2(&e->request, k->rsa->n);
484 buffer_get_bignum2(&e->request, k->rsa->e);
485 buffer_get_bignum2(&e->request, k->rsa->d);
486 buffer_get_bignum2(&e->request, k->rsa->iqmp);
487 buffer_get_bignum2(&e->request, k->rsa->p);
488 buffer_get_bignum2(&e->request, k->rsa->q);
489
490 /* Generate additional parameters */
491 rsa_generate_additional_parameters(k->rsa);
492 break;
493 default:
494 buffer_clear(&e->request);
495 goto send;
496 }
497 break;
498 }
499 /* enable blinding */
500 switch (k->type) {
501 case KEY_RSA:
502 case KEY_RSA1:
503 if (RSA_blinding_on(k->rsa, NULL) != 1) {
504 error("process_add_identity: RSA_blinding_on failed");
505 key_free(k);
506 goto send;
507 }
508 break;
509 }
510 comment = buffer_get_string(&e->request, NULL);
511 if (k == NULL) {
512 xfree(comment);
513 goto send;
514 }
515 success = 1;
516 while (buffer_len(&e->request)) {
517 switch (buffer_get_char(&e->request)) {
518 case SSH_AGENT_CONSTRAIN_LIFETIME:
519 death = time(NULL) + buffer_get_int(&e->request);
520 break;
521 case SSH_AGENT_CONSTRAIN_CONFIRM:
522 confirm = 1;
523 break;
524 default:
525 break;
526 }
527 }
528 if (lifetime && !death)
529 death = time(NULL) + lifetime;
530 if (lookup_identity(k, version) == NULL) {
531 Identity *id = xmalloc(sizeof(Identity));
532 id->key = k;
533 id->comment = comment;
534 id->death = death;
535 id->confirm = confirm;
536 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
537 /* Increment the number of identities. */
538 tab->nentries++;
539 } else {
540 key_free(k);
541 xfree(comment);
542 }
543 send:
544 buffer_put_int(&e->output, 1);
545 buffer_put_char(&e->output,
546 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
547 }
548
549 /* XXX todo: encrypt sensitive data with passphrase */
550 static void
551 process_lock_agent(SocketEntry *e, int lock)
552 {
553 int success = 0;
554 char *passwd;
555
556 passwd = buffer_get_string(&e->request, NULL);
557 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
558 locked = 0;
559 memset(lock_passwd, 0, strlen(lock_passwd));
560 xfree(lock_passwd);
561 lock_passwd = NULL;
562 success = 1;
563 } else if (!locked && lock) {
564 locked = 1;
565 lock_passwd = xstrdup(passwd);
566 success = 1;
567 }
568 memset(passwd, 0, strlen(passwd));
569 xfree(passwd);
570
571 buffer_put_int(&e->output, 1);
572 buffer_put_char(&e->output,
573 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
574 }
575
576 static void
577 no_identities(SocketEntry *e, u_int type)
578 {
579 Buffer msg;
580
581 buffer_init(&msg);
582 buffer_put_char(&msg,
583 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
584 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
585 buffer_put_int(&msg, 0);
586 buffer_put_int(&e->output, buffer_len(&msg));
587 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
588 buffer_free(&msg);
589 }
590
591 #ifdef SMARTCARD
592 static void
593 process_add_smartcard_key (SocketEntry *e)
594 {
595 char *sc_reader_id = NULL, *pin;
596 int i, version, success = 0, death = 0, confirm = 0;
597 Key **keys, *k;
598 Identity *id;
599 Idtab *tab;
600
601 sc_reader_id = buffer_get_string(&e->request, NULL);
602 pin = buffer_get_string(&e->request, NULL);
603
604 while (buffer_len(&e->request)) {
605 switch (buffer_get_char(&e->request)) {
606 case SSH_AGENT_CONSTRAIN_LIFETIME:
607 death = time(NULL) + buffer_get_int(&e->request);
608 break;
609 case SSH_AGENT_CONSTRAIN_CONFIRM:
610 confirm = 1;
611 break;
612 default:
613 break;
614 }
615 }
616 if (lifetime && !death)
617 death = time(NULL) + lifetime;
618
619 keys = sc_get_keys(sc_reader_id, pin);
620 xfree(sc_reader_id);
621 xfree(pin);
622
623 if (keys == NULL || keys[0] == NULL) {
624 error("sc_get_keys failed");
625 goto send;
626 }
627 for (i = 0; keys[i] != NULL; i++) {
628 k = keys[i];
629 version = k->type == KEY_RSA1 ? 1 : 2;
630 tab = idtab_lookup(version);
631 if (lookup_identity(k, version) == NULL) {
632 id = xmalloc(sizeof(Identity));
633 id->key = k;
634 id->comment = sc_get_key_label(k);
635 id->death = death;
636 id->confirm = confirm;
637 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
638 tab->nentries++;
639 success = 1;
640 } else {
641 key_free(k);
642 }
643 keys[i] = NULL;
644 }
645 xfree(keys);
646 send:
647 buffer_put_int(&e->output, 1);
648 buffer_put_char(&e->output,
649 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
650 }
651
652 static void
653 process_remove_smartcard_key(SocketEntry *e)
654 {
655 char *sc_reader_id = NULL, *pin;
656 int i, version, success = 0;
657 Key **keys, *k = NULL;
658 Identity *id;
659 Idtab *tab;
660
661 sc_reader_id = buffer_get_string(&e->request, NULL);
662 pin = buffer_get_string(&e->request, NULL);
663 keys = sc_get_keys(sc_reader_id, pin);
664 xfree(sc_reader_id);
665 xfree(pin);
666
667 if (keys == NULL || keys[0] == NULL) {
668 error("sc_get_keys failed");
669 goto send;
670 }
671 for (i = 0; keys[i] != NULL; i++) {
672 k = keys[i];
673 version = k->type == KEY_RSA1 ? 1 : 2;
674 if ((id = lookup_identity(k, version)) != NULL) {
675 tab = idtab_lookup(version);
676 TAILQ_REMOVE(&tab->idlist, id, next);
677 tab->nentries--;
678 free_identity(id);
679 success = 1;
680 }
681 key_free(k);
682 keys[i] = NULL;
683 }
684 xfree(keys);
685 send:
686 buffer_put_int(&e->output, 1);
687 buffer_put_char(&e->output,
688 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
689 }
690 #endif /* SMARTCARD */
691
692 /* dispatch incoming messages */
693
694 static void
695 process_message(SocketEntry *e)
696 {
697 u_int msg_len, type;
698 u_char *cp;
699
700 /* kill dead keys */
701 reaper();
702
703 if (buffer_len(&e->input) < 5)
704 return; /* Incomplete message. */
705 cp = buffer_ptr(&e->input);
706 msg_len = get_u32(cp);
707 if (msg_len > 256 * 1024) {
708 close_socket(e);
709 return;
710 }
711 if (buffer_len(&e->input) < msg_len + 4)
712 return;
713
714 /* move the current input to e->request */
715 buffer_consume(&e->input, 4);
716 buffer_clear(&e->request);
717 buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
718 buffer_consume(&e->input, msg_len);
719 type = buffer_get_char(&e->request);
720
721 /* check wheter agent is locked */
722 if (locked && type != SSH_AGENTC_UNLOCK) {
723 buffer_clear(&e->request);
724 switch (type) {
725 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
726 case SSH2_AGENTC_REQUEST_IDENTITIES:
727 /* send empty lists */
728 no_identities(e, type);
729 break;
730 default:
731 /* send a fail message for all other request types */
732 buffer_put_int(&e->output, 1);
733 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
734 }
735 return;
736 }
737
738 debug("type %d", type);
739 switch (type) {
740 case SSH_AGENTC_LOCK:
741 case SSH_AGENTC_UNLOCK:
742 process_lock_agent(e, type == SSH_AGENTC_LOCK);
743 break;
744 /* ssh1 */
745 case SSH_AGENTC_RSA_CHALLENGE:
746 process_authentication_challenge1(e);
747 break;
748 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
749 process_request_identities(e, 1);
750 break;
751 case SSH_AGENTC_ADD_RSA_IDENTITY:
752 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
753 process_add_identity(e, 1);
754 break;
755 case SSH_AGENTC_REMOVE_RSA_IDENTITY:
756 process_remove_identity(e, 1);
757 break;
758 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
759 process_remove_all_identities(e, 1);
760 break;
761 /* ssh2 */
762 case SSH2_AGENTC_SIGN_REQUEST:
763 process_sign_request2(e);
764 break;
765 case SSH2_AGENTC_REQUEST_IDENTITIES:
766 process_request_identities(e, 2);
767 break;
768 case SSH2_AGENTC_ADD_IDENTITY:
769 case SSH2_AGENTC_ADD_ID_CONSTRAINED:
770 process_add_identity(e, 2);
771 break;
772 case SSH2_AGENTC_REMOVE_IDENTITY:
773 process_remove_identity(e, 2);
774 break;
775 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
776 process_remove_all_identities(e, 2);
777 break;
778 #ifdef SMARTCARD
779 case SSH_AGENTC_ADD_SMARTCARD_KEY:
780 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
781 process_add_smartcard_key(e);
782 break;
783 case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
784 process_remove_smartcard_key(e);
785 break;
786 #endif /* SMARTCARD */
787 default:
788 /* Unknown message. Respond with failure. */
789 error("Unknown message %d", type);
790 buffer_clear(&e->request);
791 buffer_put_int(&e->output, 1);
792 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
793 break;
794 }
795 }
796
797 static void
798 new_socket(sock_type type, int fd)
799 {
800 u_int i, old_alloc, new_alloc;
801
802 set_nonblock(fd);
803
804 if (fd > max_fd)
805 max_fd = fd;
806
807 for (i = 0; i < sockets_alloc; i++)
808 if (sockets[i].type == AUTH_UNUSED) {
809 sockets[i].fd = fd;
810 buffer_init(&sockets[i].input);
811 buffer_init(&sockets[i].output);
812 buffer_init(&sockets[i].request);
813 sockets[i].type = type;
814 return;
815 }
816 old_alloc = sockets_alloc;
817 new_alloc = sockets_alloc + 10;
818 sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
819 for (i = old_alloc; i < new_alloc; i++)
820 sockets[i].type = AUTH_UNUSED;
821 sockets_alloc = new_alloc;
822 sockets[old_alloc].fd = fd;
823 buffer_init(&sockets[old_alloc].input);
824 buffer_init(&sockets[old_alloc].output);
825 buffer_init(&sockets[old_alloc].request);
826 sockets[old_alloc].type = type;
827 }
828
829 static int
830 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
831 {
832 u_int i, sz;
833 int n = 0;
834
835 for (i = 0; i < sockets_alloc; i++) {
836 switch (sockets[i].type) {
837 case AUTH_SOCKET:
838 case AUTH_CONNECTION:
839 n = MAX(n, sockets[i].fd);
840 break;
841 case AUTH_UNUSED:
842 break;
843 default:
844 fatal("Unknown socket type %d", sockets[i].type);
845 break;
846 }
847 }
848
849 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
850 if (*fdrp == NULL || sz > *nallocp) {
851 if (*fdrp)
852 xfree(*fdrp);
853 if (*fdwp)
854 xfree(*fdwp);
855 *fdrp = xmalloc(sz);
856 *fdwp = xmalloc(sz);
857 *nallocp = sz;
858 }
859 if (n < *fdl)
860 debug("XXX shrink: %d < %d", n, *fdl);
861 *fdl = n;
862 memset(*fdrp, 0, sz);
863 memset(*fdwp, 0, sz);
864
865 for (i = 0; i < sockets_alloc; i++) {
866 switch (sockets[i].type) {
867 case AUTH_SOCKET:
868 case AUTH_CONNECTION:
869 FD_SET(sockets[i].fd, *fdrp);
870 if (buffer_len(&sockets[i].output) > 0)
871 FD_SET(sockets[i].fd, *fdwp);
872 break;
873 default:
874 break;
875 }
876 }
877 return (1);
878 }
879
880 static void
881 after_select(fd_set *readset, fd_set *writeset)
882 {
883 struct sockaddr_un sunaddr;
884 socklen_t slen;
885 char buf[1024];
886 int len, sock;
887 u_int i;
888 uid_t euid;
889 gid_t egid;
890
891 for (i = 0; i < sockets_alloc; i++)
892 switch (sockets[i].type) {
893 case AUTH_UNUSED:
894 break;
895 case AUTH_SOCKET:
896 if (FD_ISSET(sockets[i].fd, readset)) {
897 slen = sizeof(sunaddr);
898 sock = accept(sockets[i].fd,
899 (struct sockaddr *)&sunaddr, &slen);
900 if (sock < 0) {
901 error("accept from AUTH_SOCKET: %s",
902 strerror(errno));
903 break;
904 }
905 if (getpeereid(sock, &euid, &egid) < 0) {
906 error("getpeereid %d failed: %s",
907 sock, strerror(errno));
908 close(sock);
909 break;
910 }
911 if ((euid != 0) && (getuid() != euid)) {
912 error("uid mismatch: "
913 "peer euid %u != uid %u",
914 (u_int) euid, (u_int) getuid());
915 close(sock);
916 break;
917 }
918 new_socket(AUTH_CONNECTION, sock);
919 }
920 break;
921 case AUTH_CONNECTION:
922 if (buffer_len(&sockets[i].output) > 0 &&
923 FD_ISSET(sockets[i].fd, writeset)) {
924 do {
925 len = write(sockets[i].fd,
926 buffer_ptr(&sockets[i].output),
927 buffer_len(&sockets[i].output));
928 if (len == -1 && (errno == EAGAIN ||
929 errno == EINTR))
930 continue;
931 break;
932 } while (1);
933 if (len <= 0) {
934 close_socket(&sockets[i]);
935 break;
936 }
937 buffer_consume(&sockets[i].output, len);
938 }
939 if (FD_ISSET(sockets[i].fd, readset)) {
940 do {
941 len = read(sockets[i].fd, buf, sizeof(buf));
942 if (len == -1 && (errno == EAGAIN ||
943 errno == EINTR))
944 continue;
945 break;
946 } while (1);
947 if (len <= 0) {
948 close_socket(&sockets[i]);
949 break;
950 }
951 buffer_append(&sockets[i].input, buf, len);
952 process_message(&sockets[i]);
953 }
954 break;
955 default:
956 fatal("Unknown type %d", sockets[i].type);
957 }
958 }
959
960 static void
961 cleanup_socket(void)
962 {
963 if (socket_name[0])
964 unlink(socket_name);
965 if (socket_dir[0])
966 rmdir(socket_dir);
967 }
968
969 void
970 cleanup_exit(int i)
971 {
972 cleanup_socket();
973 _exit(i);
974 }
975
976 /*ARGSUSED*/
977 static void
978 cleanup_handler(int sig)
979 {
980 cleanup_socket();
981 _exit(2);
982 }
983
984 /*ARGSUSED*/
985 static void
986 check_parent_exists(int sig)
987 {
988 int save_errno = errno;
989
990 if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
991 /* printf("Parent has died - Authentication agent exiting.\n"); */
992 cleanup_handler(sig); /* safe */
993 }
994 mysignal(SIGALRM, check_parent_exists);
995 alarm(10);
996 errno = save_errno;
997 }
998
999 static void
1000 usage(void)
1001 {
1002 fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
1003 __progname);
1004 fprintf(stderr, "Options:\n");
1005 fprintf(stderr, " -c Generate C-shell commands on stdout.\n");
1006 fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n");
1007 fprintf(stderr, " -k Kill the current agent.\n");
1008 fprintf(stderr, " -d Debug mode.\n");
1009 fprintf(stderr, " -a socket Bind agent socket to given name.\n");
1010 fprintf(stderr, " -t life Default identity lifetime (seconds).\n");
1011 exit(1);
1012 }
1013
1014 int
1015 main(int ac, char **av)
1016 {
1017 int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1018 int sock, fd, ch;
1019 u_int nalloc;
1020 char *shell, *format, *pidstr, *agentsocket = NULL;
1021 fd_set *readsetp = NULL, *writesetp = NULL;
1022 struct sockaddr_un sunaddr;
1023 #ifdef HAVE_SETRLIMIT
1024 struct rlimit rlim;
1025 #endif
1026 int prev_mask;
1027 extern int optind;
1028 extern char *optarg;
1029 pid_t pid;
1030 char pidstrbuf[1 + 3 * sizeof pid];
1031
1032 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1033 sanitise_stdfd();
1034
1035 /* drop */
1036 setegid(getgid());
1037 setgid(getgid());
1038
1039 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1040 /* Disable ptrace on Linux without sgid bit */
1041 prctl(PR_SET_DUMPABLE, 0);
1042 #endif
1043
1044 SSLeay_add_all_algorithms();
1045
1046 __progname = ssh_get_progname(av[0]);
1047 init_rng();
1048 seed_rng();
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 &&
1092 strncmp(shell + strlen(shell) - 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 prev_mask = umask(0177);
1152 if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1153 perror("bind");
1154 *socket_name = '\0'; /* Don't unlink any existing file */
1155 umask(prev_mask);
1156 cleanup_exit(1);
1157 }
1158 umask(prev_mask);
1159 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1160 perror("listen");
1161 cleanup_exit(1);
1162 }
1163
1164 /*
1165 * Fork, and have the parent execute the command, if any, or present
1166 * the socket data. The child continues as the authentication agent.
1167 */
1168 if (d_flag) {
1169 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1170 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1171 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1172 SSH_AUTHSOCKET_ENV_NAME);
1173 printf("echo Agent pid %ld;\n", (long)parent_pid);
1174 goto skip;
1175 }
1176 pid = fork();
1177 if (pid == -1) {
1178 perror("fork");
1179 cleanup_exit(1);
1180 }
1181 if (pid != 0) { /* Parent - execute the given command. */
1182 close(sock);
1183 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1184 if (ac == 0) {
1185 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1186 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1187 SSH_AUTHSOCKET_ENV_NAME);
1188 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1189 SSH_AGENTPID_ENV_NAME);
1190 printf("echo Agent pid %ld;\n", (long)pid);
1191 exit(0);
1192 }
1193 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1194 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1195 perror("setenv");
1196 exit(1);
1197 }
1198 execvp(av[0], av);
1199 perror(av[0]);
1200 exit(1);
1201 }
1202 /* child */
1203 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1204
1205 if (setsid() == -1) {
1206 error("setsid: %s", strerror(errno));
1207 cleanup_exit(1);
1208 }
1209
1210 (void)chdir("/");
1211 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1212 /* XXX might close listen socket */
1213 (void)dup2(fd, STDIN_FILENO);
1214 (void)dup2(fd, STDOUT_FILENO);
1215 (void)dup2(fd, STDERR_FILENO);
1216 if (fd > 2)
1217 close(fd);
1218 }
1219
1220 #ifdef HAVE_SETRLIMIT
1221 /* deny core dumps, since memory contains unencrypted private keys */
1222 rlim.rlim_cur = rlim.rlim_max = 0;
1223 if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1224 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1225 cleanup_exit(1);
1226 }
1227 #endif
1228
1229 skip:
1230 new_socket(AUTH_SOCKET, sock);
1231 if (ac > 0) {
1232 mysignal(SIGALRM, check_parent_exists);
1233 alarm(10);
1234 }
1235 idtab_init();
1236 if (!d_flag)
1237 signal(SIGINT, SIG_IGN);
1238 signal(SIGPIPE, SIG_IGN);
1239 signal(SIGHUP, cleanup_handler);
1240 signal(SIGTERM, cleanup_handler);
1241 nalloc = 0;
1242
1243 while (1) {
1244 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1245 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1246 if (errno == EINTR)
1247 continue;
1248 fatal("select: %s", strerror(errno));
1249 }
1250 after_select(readsetp, writesetp);
1251 }
1252 /* NOTREACHED */
1253 }
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