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- sobrado@cvs.openbsd.org 2009/10/22 15:02:12
[openssh-git.git] / ssh-agent.c
blobdf3a87d9a53021252a4856f0834ab05438805e04
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 (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 #include "openbsd-compat/openssl-compat.h"
55
56 #include <errno.h>
57 #include <fcntl.h>
58 #ifdef HAVE_PATHS_H
59 # include <paths.h>
60 #endif
61 #include <signal.h>
62 #include <stdarg.h>
63 #include <stdio.h>
64 #include <stdlib.h>
65 #include <time.h>
66 #include <string.h>
67 #include <unistd.h>
68
69 #include "xmalloc.h"
70 #include "ssh.h"
71 #include "rsa.h"
72 #include "buffer.h"
73 #include "key.h"
74 #include "authfd.h"
75 #include "compat.h"
76 #include "log.h"
77 #include "misc.h"
78
79 #ifdef SMARTCARD
80 #include "scard.h"
81 #endif
82
83 #if defined(HAVE_SYS_PRCTL_H)
84 #include <sys/prctl.h> /* For prctl() and PR_SET_DUMPABLE */
85 #endif
86
87 typedef enum {
88 AUTH_UNUSED,
89 AUTH_SOCKET,
90 AUTH_CONNECTION
91 } sock_type;
92
93 typedef struct {
94 int fd;
95 sock_type type;
96 Buffer input;
97 Buffer output;
98 Buffer request;
99 } SocketEntry;
100
101 u_int sockets_alloc = 0;
102 SocketEntry *sockets = NULL;
103
104 typedef struct identity {
105 TAILQ_ENTRY(identity) next;
106 Key *key;
107 char *comment;
108 u_int death;
109 u_int confirm;
110 } Identity;
111
112 typedef struct {
113 int nentries;
114 TAILQ_HEAD(idqueue, identity) idlist;
115 } Idtab;
116
117 /* private key table, one per protocol version */
118 Idtab idtable[3];
119
120 int max_fd = 0;
121
122 /* pid of shell == parent of agent */
123 pid_t parent_pid = -1;
124 u_int parent_alive_interval = 0;
125
126 /* pathname and directory for AUTH_SOCKET */
127 char socket_name[MAXPATHLEN];
128 char socket_dir[MAXPATHLEN];
129
130 /* locking */
131 int locked = 0;
132 char *lock_passwd = NULL;
133
134 extern char *__progname;
135
136 /* Default lifetime (0 == forever) */
137 static int lifetime = 0;
138
139 static void
140 close_socket(SocketEntry *e)
141 {
142 close(e->fd);
143 e->fd = -1;
144 e->type = AUTH_UNUSED;
145 buffer_free(&e->input);
146 buffer_free(&e->output);
147 buffer_free(&e->request);
148 }
149
150 static void
151 idtab_init(void)
152 {
153 int i;
154
155 for (i = 0; i <=2; i++) {
156 TAILQ_INIT(&idtable[i].idlist);
157 idtable[i].nentries = 0;
158 }
159 }
160
161 /* return private key table for requested protocol version */
162 static Idtab *
163 idtab_lookup(int version)
164 {
165 if (version < 1 || version > 2)
166 fatal("internal error, bad protocol version %d", version);
167 return &idtable[version];
168 }
169
170 static void
171 free_identity(Identity *id)
172 {
173 key_free(id->key);
174 xfree(id->comment);
175 xfree(id);
176 }
177
178 /* return matching private key for given public key */
179 static Identity *
180 lookup_identity(Key *key, int version)
181 {
182 Identity *id;
183
184 Idtab *tab = idtab_lookup(version);
185 TAILQ_FOREACH(id, &tab->idlist, next) {
186 if (key_equal(key, id->key))
187 return (id);
188 }
189 return (NULL);
190 }
191
192 /* Check confirmation of keysign request */
193 static int
194 confirm_key(Identity *id)
195 {
196 char *p;
197 int ret = -1;
198
199 p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
200 if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
201 id->comment, p))
202 ret = 0;
203 xfree(p);
204
205 return (ret);
206 }
207
208 /* send list of supported public keys to 'client' */
209 static void
210 process_request_identities(SocketEntry *e, int version)
211 {
212 Idtab *tab = idtab_lookup(version);
213 Identity *id;
214 Buffer msg;
215
216 buffer_init(&msg);
217 buffer_put_char(&msg, (version == 1) ?
218 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
219 buffer_put_int(&msg, tab->nentries);
220 TAILQ_FOREACH(id, &tab->idlist, next) {
221 if (id->key->type == KEY_RSA1) {
222 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
223 buffer_put_bignum(&msg, id->key->rsa->e);
224 buffer_put_bignum(&msg, id->key->rsa->n);
225 } else {
226 u_char *blob;
227 u_int blen;
228 key_to_blob(id->key, &blob, &blen);
229 buffer_put_string(&msg, blob, blen);
230 xfree(blob);
231 }
232 buffer_put_cstring(&msg, id->comment);
233 }
234 buffer_put_int(&e->output, buffer_len(&msg));
235 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
236 buffer_free(&msg);
237 }
238
239 /* ssh1 only */
240 static void
241 process_authentication_challenge1(SocketEntry *e)
242 {
243 u_char buf[32], mdbuf[16], session_id[16];
244 u_int response_type;
245 BIGNUM *challenge;
246 Identity *id;
247 int i, len;
248 Buffer msg;
249 MD5_CTX md;
250 Key *key;
251
252 buffer_init(&msg);
253 key = key_new(KEY_RSA1);
254 if ((challenge = BN_new()) == NULL)
255 fatal("process_authentication_challenge1: BN_new failed");
256
257 (void) buffer_get_int(&e->request); /* ignored */
258 buffer_get_bignum(&e->request, key->rsa->e);
259 buffer_get_bignum(&e->request, key->rsa->n);
260 buffer_get_bignum(&e->request, challenge);
261
262 /* Only protocol 1.1 is supported */
263 if (buffer_len(&e->request) == 0)
264 goto failure;
265 buffer_get(&e->request, session_id, 16);
266 response_type = buffer_get_int(&e->request);
267 if (response_type != 1)
268 goto failure;
269
270 id = lookup_identity(key, 1);
271 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
272 Key *private = id->key;
273 /* Decrypt the challenge using the private key. */
274 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
275 goto failure;
276
277 /* The response is MD5 of decrypted challenge plus session id. */
278 len = BN_num_bytes(challenge);
279 if (len <= 0 || len > 32) {
280 logit("process_authentication_challenge: bad challenge length %d", len);
281 goto failure;
282 }
283 memset(buf, 0, 32);
284 BN_bn2bin(challenge, buf + 32 - len);
285 MD5_Init(&md);
286 MD5_Update(&md, buf, 32);
287 MD5_Update(&md, session_id, 16);
288 MD5_Final(mdbuf, &md);
289
290 /* Send the response. */
291 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
292 for (i = 0; i < 16; i++)
293 buffer_put_char(&msg, mdbuf[i]);
294 goto send;
295 }
296
297 failure:
298 /* Unknown identity or protocol error. Send failure. */
299 buffer_put_char(&msg, SSH_AGENT_FAILURE);
300 send:
301 buffer_put_int(&e->output, buffer_len(&msg));
302 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
303 key_free(key);
304 BN_clear_free(challenge);
305 buffer_free(&msg);
306 }
307
308 /* ssh2 only */
309 static void
310 process_sign_request2(SocketEntry *e)
311 {
312 u_char *blob, *data, *signature = NULL;
313 u_int blen, dlen, slen = 0;
314 extern int datafellows;
315 int odatafellows;
316 int ok = -1, flags;
317 Buffer msg;
318 Key *key;
319
320 datafellows = 0;
321
322 blob = buffer_get_string(&e->request, &blen);
323 data = buffer_get_string(&e->request, &dlen);
324
325 flags = buffer_get_int(&e->request);
326 odatafellows = datafellows;
327 if (flags & SSH_AGENT_OLD_SIGNATURE)
328 datafellows = SSH_BUG_SIGBLOB;
329
330 key = key_from_blob(blob, blen);
331 if (key != NULL) {
332 Identity *id = lookup_identity(key, 2);
333 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
334 ok = key_sign(id->key, &signature, &slen, data, dlen);
335 key_free(key);
336 }
337 buffer_init(&msg);
338 if (ok == 0) {
339 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
340 buffer_put_string(&msg, signature, slen);
341 } else {
342 buffer_put_char(&msg, SSH_AGENT_FAILURE);
343 }
344 buffer_put_int(&e->output, buffer_len(&msg));
345 buffer_append(&e->output, buffer_ptr(&msg),
346 buffer_len(&msg));
347 buffer_free(&msg);
348 xfree(data);
349 xfree(blob);
350 if (signature != NULL)
351 xfree(signature);
352 datafellows = odatafellows;
353 }
354
355 /* shared */
356 static void
357 process_remove_identity(SocketEntry *e, int version)
358 {
359 u_int blen, bits;
360 int success = 0;
361 Key *key = NULL;
362 u_char *blob;
363
364 switch (version) {
365 case 1:
366 key = key_new(KEY_RSA1);
367 bits = buffer_get_int(&e->request);
368 buffer_get_bignum(&e->request, key->rsa->e);
369 buffer_get_bignum(&e->request, key->rsa->n);
370
371 if (bits != key_size(key))
372 logit("Warning: identity keysize mismatch: actual %u, announced %u",
373 key_size(key), bits);
374 break;
375 case 2:
376 blob = buffer_get_string(&e->request, &blen);
377 key = key_from_blob(blob, blen);
378 xfree(blob);
379 break;
380 }
381 if (key != NULL) {
382 Identity *id = lookup_identity(key, version);
383 if (id != NULL) {
384 /*
385 * We have this key. Free the old key. Since we
386 * don't want to leave empty slots in the middle of
387 * the array, we actually free the key there and move
388 * all the entries between the empty slot and the end
389 * of the array.
390 */
391 Idtab *tab = idtab_lookup(version);
392 if (tab->nentries < 1)
393 fatal("process_remove_identity: "
394 "internal error: tab->nentries %d",
395 tab->nentries);
396 TAILQ_REMOVE(&tab->idlist, id, next);
397 free_identity(id);
398 tab->nentries--;
399 success = 1;
400 }
401 key_free(key);
402 }
403 buffer_put_int(&e->output, 1);
404 buffer_put_char(&e->output,
405 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
406 }
407
408 static void
409 process_remove_all_identities(SocketEntry *e, int version)
410 {
411 Idtab *tab = idtab_lookup(version);
412 Identity *id;
413
414 /* Loop over all identities and clear the keys. */
415 for (id = TAILQ_FIRST(&tab->idlist); id;
416 id = TAILQ_FIRST(&tab->idlist)) {
417 TAILQ_REMOVE(&tab->idlist, id, next);
418 free_identity(id);
419 }
420
421 /* Mark that there are no identities. */
422 tab->nentries = 0;
423
424 /* Send success. */
425 buffer_put_int(&e->output, 1);
426 buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
427 }
428
429 /* removes expired keys and returns number of seconds until the next expiry */
430 static u_int
431 reaper(void)
432 {
433 u_int deadline = 0, now = time(NULL);
434 Identity *id, *nxt;
435 int version;
436 Idtab *tab;
437
438 for (version = 1; version < 3; version++) {
439 tab = idtab_lookup(version);
440 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
441 nxt = TAILQ_NEXT(id, next);
442 if (id->death == 0)
443 continue;
444 if (now >= id->death) {
445 debug("expiring key '%s'", id->comment);
446 TAILQ_REMOVE(&tab->idlist, id, next);
447 free_identity(id);
448 tab->nentries--;
449 } else
450 deadline = (deadline == 0) ? id->death :
451 MIN(deadline, id->death);
452 }
453 }
454 if (deadline == 0 || deadline <= now)
455 return 0;
456 else
457 return (deadline - now);
458 }
459
460 static void
461 process_add_identity(SocketEntry *e, int version)
462 {
463 Idtab *tab = idtab_lookup(version);
464 Identity *id;
465 int type, success = 0, death = 0, confirm = 0;
466 char *type_name, *comment;
467 Key *k = NULL;
468
469 switch (version) {
470 case 1:
471 k = key_new_private(KEY_RSA1);
472 (void) buffer_get_int(&e->request); /* ignored */
473 buffer_get_bignum(&e->request, k->rsa->n);
474 buffer_get_bignum(&e->request, k->rsa->e);
475 buffer_get_bignum(&e->request, k->rsa->d);
476 buffer_get_bignum(&e->request, k->rsa->iqmp);
477
478 /* SSH and SSL have p and q swapped */
479 buffer_get_bignum(&e->request, k->rsa->q); /* p */
480 buffer_get_bignum(&e->request, k->rsa->p); /* q */
481
482 /* Generate additional parameters */
483 rsa_generate_additional_parameters(k->rsa);
484 break;
485 case 2:
486 type_name = buffer_get_string(&e->request, NULL);
487 type = key_type_from_name(type_name);
488 xfree(type_name);
489 switch (type) {
490 case KEY_DSA:
491 k = key_new_private(type);
492 buffer_get_bignum2(&e->request, k->dsa->p);
493 buffer_get_bignum2(&e->request, k->dsa->q);
494 buffer_get_bignum2(&e->request, k->dsa->g);
495 buffer_get_bignum2(&e->request, k->dsa->pub_key);
496 buffer_get_bignum2(&e->request, k->dsa->priv_key);
497 break;
498 case KEY_RSA:
499 k = key_new_private(type);
500 buffer_get_bignum2(&e->request, k->rsa->n);
501 buffer_get_bignum2(&e->request, k->rsa->e);
502 buffer_get_bignum2(&e->request, k->rsa->d);
503 buffer_get_bignum2(&e->request, k->rsa->iqmp);
504 buffer_get_bignum2(&e->request, k->rsa->p);
505 buffer_get_bignum2(&e->request, k->rsa->q);
506
507 /* Generate additional parameters */
508 rsa_generate_additional_parameters(k->rsa);
509 break;
510 default:
511 buffer_clear(&e->request);
512 goto send;
513 }
514 break;
515 }
516 /* enable blinding */
517 switch (k->type) {
518 case KEY_RSA:
519 case KEY_RSA1:
520 if (RSA_blinding_on(k->rsa, NULL) != 1) {
521 error("process_add_identity: RSA_blinding_on failed");
522 key_free(k);
523 goto send;
524 }
525 break;
526 }
527 comment = buffer_get_string(&e->request, NULL);
528 if (k == NULL) {
529 xfree(comment);
530 goto send;
531 }
532 while (buffer_len(&e->request)) {
533 switch ((type = buffer_get_char(&e->request))) {
534 case SSH_AGENT_CONSTRAIN_LIFETIME:
535 death = time(NULL) + buffer_get_int(&e->request);
536 break;
537 case SSH_AGENT_CONSTRAIN_CONFIRM:
538 confirm = 1;
539 break;
540 default:
541 error("process_add_identity: "
542 "Unknown constraint type %d", type);
543 xfree(comment);
544 key_free(k);
545 goto send;
546 }
547 }
548 success = 1;
549 if (lifetime && !death)
550 death = time(NULL) + lifetime;
551 if ((id = lookup_identity(k, version)) == NULL) {
552 id = xmalloc(sizeof(Identity));
553 id->key = k;
554 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
555 /* Increment the number of identities. */
556 tab->nentries++;
557 } else {
558 key_free(k);
559 xfree(id->comment);
560 }
561 id->comment = comment;
562 id->death = death;
563 id->confirm = confirm;
564 send:
565 buffer_put_int(&e->output, 1);
566 buffer_put_char(&e->output,
567 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
568 }
569
570 /* XXX todo: encrypt sensitive data with passphrase */
571 static void
572 process_lock_agent(SocketEntry *e, int lock)
573 {
574 int success = 0;
575 char *passwd;
576
577 passwd = buffer_get_string(&e->request, NULL);
578 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
579 locked = 0;
580 memset(lock_passwd, 0, strlen(lock_passwd));
581 xfree(lock_passwd);
582 lock_passwd = NULL;
583 success = 1;
584 } else if (!locked && lock) {
585 locked = 1;
586 lock_passwd = xstrdup(passwd);
587 success = 1;
588 }
589 memset(passwd, 0, strlen(passwd));
590 xfree(passwd);
591
592 buffer_put_int(&e->output, 1);
593 buffer_put_char(&e->output,
594 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
595 }
596
597 static void
598 no_identities(SocketEntry *e, u_int type)
599 {
600 Buffer msg;
601
602 buffer_init(&msg);
603 buffer_put_char(&msg,
604 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
605 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
606 buffer_put_int(&msg, 0);
607 buffer_put_int(&e->output, buffer_len(&msg));
608 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
609 buffer_free(&msg);
610 }
611
612 #ifdef SMARTCARD
613 static void
614 process_add_smartcard_key(SocketEntry *e)
615 {
616 char *sc_reader_id = NULL, *pin;
617 int i, type, version, success = 0, death = 0, confirm = 0;
618 Key **keys, *k;
619 Identity *id;
620 Idtab *tab;
621
622 sc_reader_id = buffer_get_string(&e->request, NULL);
623 pin = buffer_get_string(&e->request, NULL);
624
625 while (buffer_len(&e->request)) {
626 switch ((type = buffer_get_char(&e->request))) {
627 case SSH_AGENT_CONSTRAIN_LIFETIME:
628 death = time(NULL) + buffer_get_int(&e->request);
629 break;
630 case SSH_AGENT_CONSTRAIN_CONFIRM:
631 confirm = 1;
632 break;
633 default:
634 error("process_add_smartcard_key: "
635 "Unknown constraint type %d", type);
636 xfree(sc_reader_id);
637 xfree(pin);
638 goto send;
639 }
640 }
641 if (lifetime && !death)
642 death = time(NULL) + lifetime;
643
644 keys = sc_get_keys(sc_reader_id, pin);
645 xfree(sc_reader_id);
646 xfree(pin);
647
648 if (keys == NULL || keys[0] == NULL) {
649 error("sc_get_keys failed");
650 goto send;
651 }
652 for (i = 0; keys[i] != NULL; i++) {
653 k = keys[i];
654 version = k->type == KEY_RSA1 ? 1 : 2;
655 tab = idtab_lookup(version);
656 if (lookup_identity(k, version) == NULL) {
657 id = xmalloc(sizeof(Identity));
658 id->key = k;
659 id->comment = sc_get_key_label(k);
660 id->death = death;
661 id->confirm = confirm;
662 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
663 tab->nentries++;
664 success = 1;
665 } else {
666 key_free(k);
667 }
668 keys[i] = NULL;
669 }
670 xfree(keys);
671 send:
672 buffer_put_int(&e->output, 1);
673 buffer_put_char(&e->output,
674 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
675 }
676
677 static void
678 process_remove_smartcard_key(SocketEntry *e)
679 {
680 char *sc_reader_id = NULL, *pin;
681 int i, version, success = 0;
682 Key **keys, *k = NULL;
683 Identity *id;
684 Idtab *tab;
685
686 sc_reader_id = buffer_get_string(&e->request, NULL);
687 pin = buffer_get_string(&e->request, NULL);
688 keys = sc_get_keys(sc_reader_id, pin);
689 xfree(sc_reader_id);
690 xfree(pin);
691
692 if (keys == NULL || keys[0] == NULL) {
693 error("sc_get_keys failed");
694 goto send;
695 }
696 for (i = 0; keys[i] != NULL; i++) {
697 k = keys[i];
698 version = k->type == KEY_RSA1 ? 1 : 2;
699 if ((id = lookup_identity(k, version)) != NULL) {
700 tab = idtab_lookup(version);
701 TAILQ_REMOVE(&tab->idlist, id, next);
702 tab->nentries--;
703 free_identity(id);
704 success = 1;
705 }
706 key_free(k);
707 keys[i] = NULL;
708 }
709 xfree(keys);
710 send:
711 buffer_put_int(&e->output, 1);
712 buffer_put_char(&e->output,
713 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
714 }
715 #endif /* SMARTCARD */
716
717 /* dispatch incoming messages */
718
719 static void
720 process_message(SocketEntry *e)
721 {
722 u_int msg_len, type;
723 u_char *cp;
724
725 if (buffer_len(&e->input) < 5)
726 return; /* Incomplete message. */
727 cp = buffer_ptr(&e->input);
728 msg_len = get_u32(cp);
729 if (msg_len > 256 * 1024) {
730 close_socket(e);
731 return;
732 }
733 if (buffer_len(&e->input) < msg_len + 4)
734 return;
735
736 /* move the current input to e->request */
737 buffer_consume(&e->input, 4);
738 buffer_clear(&e->request);
739 buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
740 buffer_consume(&e->input, msg_len);
741 type = buffer_get_char(&e->request);
742
743 /* check wheter agent is locked */
744 if (locked && type != SSH_AGENTC_UNLOCK) {
745 buffer_clear(&e->request);
746 switch (type) {
747 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
748 case SSH2_AGENTC_REQUEST_IDENTITIES:
749 /* send empty lists */
750 no_identities(e, type);
751 break;
752 default:
753 /* send a fail message for all other request types */
754 buffer_put_int(&e->output, 1);
755 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
756 }
757 return;
758 }
759
760 debug("type %d", type);
761 switch (type) {
762 case SSH_AGENTC_LOCK:
763 case SSH_AGENTC_UNLOCK:
764 process_lock_agent(e, type == SSH_AGENTC_LOCK);
765 break;
766 /* ssh1 */
767 case SSH_AGENTC_RSA_CHALLENGE:
768 process_authentication_challenge1(e);
769 break;
770 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
771 process_request_identities(e, 1);
772 break;
773 case SSH_AGENTC_ADD_RSA_IDENTITY:
774 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
775 process_add_identity(e, 1);
776 break;
777 case SSH_AGENTC_REMOVE_RSA_IDENTITY:
778 process_remove_identity(e, 1);
779 break;
780 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
781 process_remove_all_identities(e, 1);
782 break;
783 /* ssh2 */
784 case SSH2_AGENTC_SIGN_REQUEST:
785 process_sign_request2(e);
786 break;
787 case SSH2_AGENTC_REQUEST_IDENTITIES:
788 process_request_identities(e, 2);
789 break;
790 case SSH2_AGENTC_ADD_IDENTITY:
791 case SSH2_AGENTC_ADD_ID_CONSTRAINED:
792 process_add_identity(e, 2);
793 break;
794 case SSH2_AGENTC_REMOVE_IDENTITY:
795 process_remove_identity(e, 2);
796 break;
797 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
798 process_remove_all_identities(e, 2);
799 break;
800 #ifdef SMARTCARD
801 case SSH_AGENTC_ADD_SMARTCARD_KEY:
802 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
803 process_add_smartcard_key(e);
804 break;
805 case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
806 process_remove_smartcard_key(e);
807 break;
808 #endif /* SMARTCARD */
809 default:
810 /* Unknown message. Respond with failure. */
811 error("Unknown message %d", type);
812 buffer_clear(&e->request);
813 buffer_put_int(&e->output, 1);
814 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
815 break;
816 }
817 }
818
819 static void
820 new_socket(sock_type type, int fd)
821 {
822 u_int i, old_alloc, new_alloc;
823
824 set_nonblock(fd);
825
826 if (fd > max_fd)
827 max_fd = fd;
828
829 for (i = 0; i < sockets_alloc; i++)
830 if (sockets[i].type == AUTH_UNUSED) {
831 sockets[i].fd = fd;
832 buffer_init(&sockets[i].input);
833 buffer_init(&sockets[i].output);
834 buffer_init(&sockets[i].request);
835 sockets[i].type = type;
836 return;
837 }
838 old_alloc = sockets_alloc;
839 new_alloc = sockets_alloc + 10;
840 sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
841 for (i = old_alloc; i < new_alloc; i++)
842 sockets[i].type = AUTH_UNUSED;
843 sockets_alloc = new_alloc;
844 sockets[old_alloc].fd = fd;
845 buffer_init(&sockets[old_alloc].input);
846 buffer_init(&sockets[old_alloc].output);
847 buffer_init(&sockets[old_alloc].request);
848 sockets[old_alloc].type = type;
849 }
850
851 static int
852 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
853 struct timeval **tvpp)
854 {
855 u_int i, sz, deadline;
856 int n = 0;
857 static struct timeval tv;
858
859 for (i = 0; i < sockets_alloc; i++) {
860 switch (sockets[i].type) {
861 case AUTH_SOCKET:
862 case AUTH_CONNECTION:
863 n = MAX(n, sockets[i].fd);
864 break;
865 case AUTH_UNUSED:
866 break;
867 default:
868 fatal("Unknown socket type %d", sockets[i].type);
869 break;
870 }
871 }
872
873 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
874 if (*fdrp == NULL || sz > *nallocp) {
875 if (*fdrp)
876 xfree(*fdrp);
877 if (*fdwp)
878 xfree(*fdwp);
879 *fdrp = xmalloc(sz);
880 *fdwp = xmalloc(sz);
881 *nallocp = sz;
882 }
883 if (n < *fdl)
884 debug("XXX shrink: %d < %d", n, *fdl);
885 *fdl = n;
886 memset(*fdrp, 0, sz);
887 memset(*fdwp, 0, sz);
888
889 for (i = 0; i < sockets_alloc; i++) {
890 switch (sockets[i].type) {
891 case AUTH_SOCKET:
892 case AUTH_CONNECTION:
893 FD_SET(sockets[i].fd, *fdrp);
894 if (buffer_len(&sockets[i].output) > 0)
895 FD_SET(sockets[i].fd, *fdwp);
896 break;
897 default:
898 break;
899 }
900 }
901 deadline = reaper();
902 if (parent_alive_interval != 0)
903 deadline = (deadline == 0) ? parent_alive_interval :
904 MIN(deadline, parent_alive_interval);
905 if (deadline == 0) {
906 *tvpp = NULL;
907 } else {
908 tv.tv_sec = deadline;
909 tv.tv_usec = 0;
910 *tvpp = &tv;
911 }
912 return (1);
913 }
914
915 static void
916 after_select(fd_set *readset, fd_set *writeset)
917 {
918 struct sockaddr_un sunaddr;
919 socklen_t slen;
920 char buf[1024];
921 int len, sock;
922 u_int i, orig_alloc;
923 uid_t euid;
924 gid_t egid;
925
926 for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
927 switch (sockets[i].type) {
928 case AUTH_UNUSED:
929 break;
930 case AUTH_SOCKET:
931 if (FD_ISSET(sockets[i].fd, readset)) {
932 slen = sizeof(sunaddr);
933 sock = accept(sockets[i].fd,
934 (struct sockaddr *)&sunaddr, &slen);
935 if (sock < 0) {
936 error("accept from AUTH_SOCKET: %s",
937 strerror(errno));
938 break;
939 }
940 if (getpeereid(sock, &euid, &egid) < 0) {
941 error("getpeereid %d failed: %s",
942 sock, strerror(errno));
943 close(sock);
944 break;
945 }
946 if ((euid != 0) && (getuid() != euid)) {
947 error("uid mismatch: "
948 "peer euid %u != uid %u",
949 (u_int) euid, (u_int) getuid());
950 close(sock);
951 break;
952 }
953 new_socket(AUTH_CONNECTION, sock);
954 }
955 break;
956 case AUTH_CONNECTION:
957 if (buffer_len(&sockets[i].output) > 0 &&
958 FD_ISSET(sockets[i].fd, writeset)) {
959 len = write(sockets[i].fd,
960 buffer_ptr(&sockets[i].output),
961 buffer_len(&sockets[i].output));
962 if (len == -1 && (errno == EAGAIN ||
963 errno == EWOULDBLOCK ||
964 errno == EINTR))
965 continue;
966 if (len <= 0) {
967 close_socket(&sockets[i]);
968 break;
969 }
970 buffer_consume(&sockets[i].output, len);
971 }
972 if (FD_ISSET(sockets[i].fd, readset)) {
973 len = read(sockets[i].fd, buf, sizeof(buf));
974 if (len == -1 && (errno == EAGAIN ||
975 errno == EWOULDBLOCK ||
976 errno == EINTR))
977 continue;
978 if (len <= 0) {
979 close_socket(&sockets[i]);
980 break;
981 }
982 buffer_append(&sockets[i].input, buf, len);
983 process_message(&sockets[i]);
984 }
985 break;
986 default:
987 fatal("Unknown type %d", sockets[i].type);
988 }
989 }
990
991 static void
992 cleanup_socket(void)
993 {
994 if (socket_name[0])
995 unlink(socket_name);
996 if (socket_dir[0])
997 rmdir(socket_dir);
998 }
999
1000 void
1001 cleanup_exit(int i)
1002 {
1003 cleanup_socket();
1004 _exit(i);
1005 }
1006
1007 /*ARGSUSED*/
1008 static void
1009 cleanup_handler(int sig)
1010 {
1011 cleanup_socket();
1012 _exit(2);
1013 }
1014
1015 static void
1016 check_parent_exists(void)
1017 {
1018 if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
1019 /* printf("Parent has died - Authentication agent exiting.\n"); */
1020 cleanup_socket();
1021 _exit(2);
1022 }
1023 }
1024
1025 static void
1026 usage(void)
1027 {
1028 fprintf(stderr, "usage: %s [options] [command [arg ...]]\n",
1029 __progname);
1030 fprintf(stderr, "Options:\n");
1031 fprintf(stderr, " -c Generate C-shell commands on stdout.\n");
1032 fprintf(stderr, " -s Generate Bourne shell commands on stdout.\n");
1033 fprintf(stderr, " -k Kill the current agent.\n");
1034 fprintf(stderr, " -d Debug mode.\n");
1035 fprintf(stderr, " -a socket Bind agent socket to given name.\n");
1036 fprintf(stderr, " -t life Default identity lifetime (seconds).\n");
1037 exit(1);
1038 }
1039
1040 int
1041 main(int ac, char **av)
1042 {
1043 int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1044 int sock, fd, ch, result, saved_errno;
1045 u_int nalloc;
1046 char *shell, *format, *pidstr, *agentsocket = NULL;
1047 fd_set *readsetp = NULL, *writesetp = NULL;
1048 struct sockaddr_un sunaddr;
1049 #ifdef HAVE_SETRLIMIT
1050 struct rlimit rlim;
1051 #endif
1052 int prev_mask;
1053 extern int optind;
1054 extern char *optarg;
1055 pid_t pid;
1056 char pidstrbuf[1 + 3 * sizeof pid];
1057 struct timeval *tvp = NULL;
1058 size_t len;
1059
1060 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1061 sanitise_stdfd();
1062
1063 /* drop */
1064 setegid(getgid());
1065 setgid(getgid());
1066
1067 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1068 /* Disable ptrace on Linux without sgid bit */
1069 prctl(PR_SET_DUMPABLE, 0);
1070 #endif
1071
1072 SSLeay_add_all_algorithms();
1073
1074 __progname = ssh_get_progname(av[0]);
1075 init_rng();
1076 seed_rng();
1077
1078 while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1079 switch (ch) {
1080 case 'c':
1081 if (s_flag)
1082 usage();
1083 c_flag++;
1084 break;
1085 case 'k':
1086 k_flag++;
1087 break;
1088 case 's':
1089 if (c_flag)
1090 usage();
1091 s_flag++;
1092 break;
1093 case 'd':
1094 if (d_flag)
1095 usage();
1096 d_flag++;
1097 break;
1098 case 'a':
1099 agentsocket = optarg;
1100 break;
1101 case 't':
1102 if ((lifetime = convtime(optarg)) == -1) {
1103 fprintf(stderr, "Invalid lifetime\n");
1104 usage();
1105 }
1106 break;
1107 default:
1108 usage();
1109 }
1110 }
1111 ac -= optind;
1112 av += optind;
1113
1114 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1115 usage();
1116
1117 if (ac == 0 && !c_flag && !s_flag) {
1118 shell = getenv("SHELL");
1119 if (shell != NULL && (len = strlen(shell)) > 2 &&
1120 strncmp(shell + len - 3, "csh", 3) == 0)
1121 c_flag = 1;
1122 }
1123 if (k_flag) {
1124 const char *errstr = NULL;
1125
1126 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1127 if (pidstr == NULL) {
1128 fprintf(stderr, "%s not set, cannot kill agent\n",
1129 SSH_AGENTPID_ENV_NAME);
1130 exit(1);
1131 }
1132 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1133 if (errstr) {
1134 fprintf(stderr,
1135 "%s=\"%s\", which is not a good PID: %s\n",
1136 SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1137 exit(1);
1138 }
1139 if (kill(pid, SIGTERM) == -1) {
1140 perror("kill");
1141 exit(1);
1142 }
1143 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1144 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1145 printf(format, SSH_AGENTPID_ENV_NAME);
1146 printf("echo Agent pid %ld killed;\n", (long)pid);
1147 exit(0);
1148 }
1149 parent_pid = getpid();
1150
1151 if (agentsocket == NULL) {
1152 /* Create private directory for agent socket */
1153 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1154 if (mkdtemp(socket_dir) == NULL) {
1155 perror("mkdtemp: private socket dir");
1156 exit(1);
1157 }
1158 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1159 (long)parent_pid);
1160 } else {
1161 /* Try to use specified agent socket */
1162 socket_dir[0] = '\0';
1163 strlcpy(socket_name, agentsocket, sizeof socket_name);
1164 }
1165
1166 /*
1167 * Create socket early so it will exist before command gets run from
1168 * the parent.
1169 */
1170 sock = socket(AF_UNIX, SOCK_STREAM, 0);
1171 if (sock < 0) {
1172 perror("socket");
1173 *socket_name = '\0'; /* Don't unlink any existing file */
1174 cleanup_exit(1);
1175 }
1176 memset(&sunaddr, 0, sizeof(sunaddr));
1177 sunaddr.sun_family = AF_UNIX;
1178 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1179 prev_mask = umask(0177);
1180 if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1181 perror("bind");
1182 *socket_name = '\0'; /* Don't unlink any existing file */
1183 umask(prev_mask);
1184 cleanup_exit(1);
1185 }
1186 umask(prev_mask);
1187 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1188 perror("listen");
1189 cleanup_exit(1);
1190 }
1191
1192 /*
1193 * Fork, and have the parent execute the command, if any, or present
1194 * the socket data. The child continues as the authentication agent.
1195 */
1196 if (d_flag) {
1197 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1198 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1199 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1200 SSH_AUTHSOCKET_ENV_NAME);
1201 printf("echo Agent pid %ld;\n", (long)parent_pid);
1202 goto skip;
1203 }
1204 pid = fork();
1205 if (pid == -1) {
1206 perror("fork");
1207 cleanup_exit(1);
1208 }
1209 if (pid != 0) { /* Parent - execute the given command. */
1210 close(sock);
1211 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1212 if (ac == 0) {
1213 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1214 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1215 SSH_AUTHSOCKET_ENV_NAME);
1216 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1217 SSH_AGENTPID_ENV_NAME);
1218 printf("echo Agent pid %ld;\n", (long)pid);
1219 exit(0);
1220 }
1221 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1222 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1223 perror("setenv");
1224 exit(1);
1225 }
1226 execvp(av[0], av);
1227 perror(av[0]);
1228 exit(1);
1229 }
1230 /* child */
1231 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1232
1233 if (setsid() == -1) {
1234 error("setsid: %s", strerror(errno));
1235 cleanup_exit(1);
1236 }
1237
1238 (void)chdir("/");
1239 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1240 /* XXX might close listen socket */
1241 (void)dup2(fd, STDIN_FILENO);
1242 (void)dup2(fd, STDOUT_FILENO);
1243 (void)dup2(fd, STDERR_FILENO);
1244 if (fd > 2)
1245 close(fd);
1246 }
1247
1248 #ifdef HAVE_SETRLIMIT
1249 /* deny core dumps, since memory contains unencrypted private keys */
1250 rlim.rlim_cur = rlim.rlim_max = 0;
1251 if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1252 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1253 cleanup_exit(1);
1254 }
1255 #endif
1256
1257 skip:
1258 new_socket(AUTH_SOCKET, sock);
1259 if (ac > 0)
1260 parent_alive_interval = 10;
1261 idtab_init();
1262 if (!d_flag)
1263 signal(SIGINT, SIG_IGN);
1264 signal(SIGPIPE, SIG_IGN);
1265 signal(SIGHUP, cleanup_handler);
1266 signal(SIGTERM, cleanup_handler);
1267 nalloc = 0;
1268
1269 while (1) {
1270 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1271 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1272 saved_errno = errno;
1273 if (parent_alive_interval != 0)
1274 check_parent_exists();
1275 (void) reaper(); /* remove expired keys */
1276 if (result < 0) {
1277 if (saved_errno == EINTR)
1278 continue;
1279 fatal("select: %s", strerror(saved_errno));
1280 } else if (result > 0)
1281 after_select(readsetp, writesetp);
1282 }
1283 /* NOTREACHED */
1284 }
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