1 /*
2 * Copyright 2009 Sun Microsystems, Inc. All rights reserved.
3 * Use is subject to license terms.
4 */
5
6 /*
7 * Author: Tatu Ylonen <ylo@cs.hut.fi>
8 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
9 * All rights reserved
10 * The authentication agent program.
11 *
12 * As far as I am concerned, the code I have written for this software
13 * can be used freely for any purpose. Any derived versions of this
14 * software must be clearly marked as such, and if the derived work is
15 * incompatible with the protocol description in the RFC file, it must be
16 * called by a name other than "ssh" or "Secure Shell".
17 *
18 * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
19 *
20 * Redistribution and use in source and binary forms, with or without
21 * modification, are permitted provided that the following conditions
22 * are met:
23 * 1. Redistributions of source code must retain the above copyright
24 * notice, this list of conditions and the following disclaimer.
25 * 2. Redistributions in binary form must reproduce the above copyright
26 * notice, this list of conditions and the following disclaimer in the
27 * documentation and/or other materials provided with the distribution.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
30 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
31 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
32 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
33 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
34 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
38 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 */
40
41 #include "includes.h"
42 #include "sys-queue.h"
43 RCSID("$OpenBSD: ssh-agent.c,v 1.159 2008/06/28 14:05:15 djm Exp $");
44
45 #ifdef HAVE_SOLARIS_PRIVILEGE
46 #include <priv.h>
47 #endif /* HAVE_SOLARIS_PRIVILEGE */
48
49 #include <openssl/evp.h>
50 #include <openssl/md5.h>
51
52 #include "ssh.h"
53 #include "rsa.h"
54 #include "buffer.h"
55 #include "bufaux.h"
56 #include "xmalloc.h"
57 #include "key.h"
58 #include "authfd.h"
59 #include "compat.h"
60 #include "log.h"
61 #include "readpass.h"
62 #include "misc.h"
63
64 typedef enum {
65 AUTH_UNUSED,
66 AUTH_SOCKET,
67 AUTH_CONNECTION
68 } sock_type;
69
70 typedef struct {
71 int fd;
72 sock_type type;
73 Buffer input;
74 Buffer output;
75 Buffer request;
76 } SocketEntry;
77
78 u_int sockets_alloc = 0;
79 SocketEntry *sockets = NULL;
80
81 typedef struct identity {
82 TAILQ_ENTRY(identity) next;
83 Key *key;
84 char *comment;
85 u_int death;
86 u_int confirm;
87 } Identity;
88
89 typedef struct {
90 int nentries;
91 TAILQ_HEAD(idqueue, identity) idlist;
92 } Idtab;
93
94 /* private key table, one per protocol version */
95 Idtab idtable[3];
96
97 int max_fd = 0;
98
99 /* pid of shell == parent of agent */
100 pid_t parent_pid = -1;
101 u_int parent_alive_interval = 0;
102
103 /* pathname and directory for AUTH_SOCKET */
104 char socket_name[MAXPATHLEN];
105 char socket_dir[MAXPATHLEN];
106
107 /* locking */
108 int locked = 0;
109 char *lock_passwd = NULL;
110
111 #ifdef HAVE___PROGNAME
112 extern char *__progname;
113 #else
114 char *__progname;
115 #endif
116
117 /* Default lifetime (0 == forever) */
118 static int lifetime = 0;
119
120 static void
close_socket(SocketEntry * e)121 close_socket(SocketEntry *e)
122 {
123 close(e->fd);
124 e->fd = -1;
125 e->type = AUTH_UNUSED;
126 buffer_free(&e->input);
127 buffer_free(&e->output);
128 buffer_free(&e->request);
129 }
130
131 static void
idtab_init(void)132 idtab_init(void)
133 {
134 int i;
135
136 for (i = 0; i <=2; i++) {
137 TAILQ_INIT(&idtable[i].idlist);
138 idtable[i].nentries = 0;
139 }
140 }
141
142 /* return private key table for requested protocol version */
143 static Idtab *
idtab_lookup(int version)144 idtab_lookup(int version)
145 {
146 if (version < 1 || version > 2)
147 fatal("internal error, bad protocol version %d", version);
148 return &idtable[version];
149 }
150
151 static void
free_identity(Identity * id)152 free_identity(Identity *id)
153 {
154 key_free(id->key);
155 xfree(id->comment);
156 xfree(id);
157 }
158
159 /* return matching private key for given public key */
160 static Identity *
lookup_identity(Key * key,int version)161 lookup_identity(Key *key, int version)
162 {
163 Identity *id;
164
165 Idtab *tab = idtab_lookup(version);
166 TAILQ_FOREACH(id, &tab->idlist, next) {
167 if (key_equal(key, id->key))
168 return (id);
169 }
170 return (NULL);
171 }
172
173 /* Check confirmation of keysign request */
174 static int
confirm_key(Identity * id)175 confirm_key(Identity *id)
176 {
177 char *p;
178 int ret = -1;
179
180 p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
181 if (ask_permission(
182 gettext("Allow use of key %s?\nKey fingerprint %s."),
183 id->comment, p))
184 ret = 0;
185 xfree(p);
186
187 return (ret);
188 }
189
190 /* send list of supported public keys to 'client' */
191 static void
process_request_identities(SocketEntry * e,int version)192 process_request_identities(SocketEntry *e, int version)
193 {
194 Idtab *tab = idtab_lookup(version);
195 Identity *id;
196 Buffer msg;
197
198 buffer_init(&msg);
199 buffer_put_char(&msg, (version == 1) ?
200 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
201 buffer_put_int(&msg, tab->nentries);
202 TAILQ_FOREACH(id, &tab->idlist, next) {
203 if (id->key->type == KEY_RSA1) {
204 buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
205 buffer_put_bignum(&msg, id->key->rsa->e);
206 buffer_put_bignum(&msg, id->key->rsa->n);
207 } else {
208 u_char *blob;
209 u_int blen;
210 key_to_blob(id->key, &blob, &blen);
211 buffer_put_string(&msg, blob, blen);
212 xfree(blob);
213 }
214 buffer_put_cstring(&msg, id->comment);
215 }
216 buffer_put_int(&e->output, buffer_len(&msg));
217 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
218 buffer_free(&msg);
219 }
220
221 /* ssh1 only */
222 static void
process_authentication_challenge1(SocketEntry * e)223 process_authentication_challenge1(SocketEntry *e)
224 {
225 u_char buf[32], mdbuf[16], session_id[16];
226 u_int response_type;
227 BIGNUM *challenge;
228 Identity *id;
229 int i, len;
230 Buffer msg;
231 MD5_CTX md;
232 Key *key;
233
234 buffer_init(&msg);
235 key = key_new(KEY_RSA1);
236 if ((challenge = BN_new()) == NULL)
237 fatal("process_authentication_challenge1: BN_new failed");
238
239 (void) buffer_get_int(&e->request); /* ignored */
240 buffer_get_bignum(&e->request, key->rsa->e);
241 buffer_get_bignum(&e->request, key->rsa->n);
242 buffer_get_bignum(&e->request, challenge);
243
244 /* Only protocol 1.1 is supported */
245 if (buffer_len(&e->request) == 0)
246 goto failure;
247 buffer_get(&e->request, session_id, 16);
248 response_type = buffer_get_int(&e->request);
249 if (response_type != 1)
250 goto failure;
251
252 id = lookup_identity(key, 1);
253 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
254 Key *private = id->key;
255 /* Decrypt the challenge using the private key. */
256 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
257 goto failure;
258
259 /* The response is MD5 of decrypted challenge plus session id. */
260 len = BN_num_bytes(challenge);
261 if (len <= 0 || len > 32) {
262 log("process_authentication_challenge: bad challenge length %d", len);
263 goto failure;
264 }
265 memset(buf, 0, 32);
266 BN_bn2bin(challenge, buf + 32 - len);
267 MD5_Init(&md);
268 MD5_Update(&md, buf, 32);
269 MD5_Update(&md, session_id, 16);
270 MD5_Final(mdbuf, &md);
271
272 /* Send the response. */
273 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
274 for (i = 0; i < 16; i++)
275 buffer_put_char(&msg, mdbuf[i]);
276 goto send;
277 }
278
279 failure:
280 /* Unknown identity or protocol error. Send failure. */
281 buffer_put_char(&msg, SSH_AGENT_FAILURE);
282 send:
283 buffer_put_int(&e->output, buffer_len(&msg));
284 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
285 key_free(key);
286 BN_clear_free(challenge);
287 buffer_free(&msg);
288 }
289
290 /* ssh2 only */
291 static void
process_sign_request2(SocketEntry * e)292 process_sign_request2(SocketEntry *e)
293 {
294 u_char *blob, *data, *signature = NULL;
295 u_int blen, dlen, slen = 0;
296 extern uint32_t datafellows;
297 int odatafellows;
298 int ok = -1, flags;
299 Buffer msg;
300 Key *key;
301
302 datafellows = 0;
303
304 blob = buffer_get_string(&e->request, &blen);
305 data = buffer_get_string(&e->request, &dlen);
306
307 flags = buffer_get_int(&e->request);
308 odatafellows = datafellows;
309 if (flags & SSH_AGENT_OLD_SIGNATURE)
310 datafellows = SSH_BUG_SIGBLOB;
311
312 key = key_from_blob(blob, blen);
313 if (key != NULL) {
314 Identity *id = lookup_identity(key, 2);
315 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
316 ok = key_sign(id->key, &signature, &slen, data, dlen);
317 key_free(key);
318 }
319 buffer_init(&msg);
320 if (ok == 0) {
321 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
322 buffer_put_string(&msg, signature, slen);
323 } else {
324 buffer_put_char(&msg, SSH_AGENT_FAILURE);
325 }
326 buffer_put_int(&e->output, buffer_len(&msg));
327 buffer_append(&e->output, buffer_ptr(&msg),
328 buffer_len(&msg));
329 buffer_free(&msg);
330 xfree(data);
331 xfree(blob);
332 if (signature != NULL)
333 xfree(signature);
334 datafellows = odatafellows;
335 }
336
337 /* shared */
338 static void
process_remove_identity(SocketEntry * e,int version)339 process_remove_identity(SocketEntry *e, int version)
340 {
341 u_int blen, bits;
342 int success = 0;
343 Key *key = NULL;
344 u_char *blob;
345
346 switch (version) {
347 case 1:
348 key = key_new(KEY_RSA1);
349 bits = buffer_get_int(&e->request);
350 buffer_get_bignum(&e->request, key->rsa->e);
351 buffer_get_bignum(&e->request, key->rsa->n);
352
353 if (bits != key_size(key))
354 log("Warning: identity keysize mismatch: actual %u, announced %u",
355 key_size(key), bits);
356 break;
357 case 2:
358 blob = buffer_get_string(&e->request, &blen);
359 key = key_from_blob(blob, blen);
360 xfree(blob);
361 break;
362 }
363 if (key != NULL) {
364 Identity *id = lookup_identity(key, version);
365 if (id != NULL) {
366 /*
367 * We have this key. Free the old key. Since we
368 * don't want to leave empty slots in the middle of
369 * the array, we actually free the key there and move
370 * all the entries between the empty slot and the end
371 * of the array.
372 */
373 Idtab *tab = idtab_lookup(version);
374 if (tab->nentries < 1)
375 fatal("process_remove_identity: "
376 "internal error: tab->nentries %d",
377 tab->nentries);
378 TAILQ_REMOVE(&tab->idlist, id, next);
379 free_identity(id);
380 tab->nentries--;
381 success = 1;
382 }
383 key_free(key);
384 }
385 buffer_put_int(&e->output, 1);
386 buffer_put_char(&e->output,
387 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
388 }
389
390 static void
process_remove_all_identities(SocketEntry * e,int version)391 process_remove_all_identities(SocketEntry *e, int version)
392 {
393 Idtab *tab = idtab_lookup(version);
394 Identity *id;
395
396 /* Loop over all identities and clear the keys. */
397 for (id = TAILQ_FIRST(&tab->idlist); id;
398 id = TAILQ_FIRST(&tab->idlist)) {
399 TAILQ_REMOVE(&tab->idlist, id, next);
400 free_identity(id);
401 }
402
403 /* Mark that there are no identities. */
404 tab->nentries = 0;
405
406 /* Send success. */
407 buffer_put_int(&e->output, 1);
408 buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
409 }
410
411 /* removes expired keys and returns number of seconds until the next expiry */
412 static u_int
reaper(void)413 reaper(void)
414 {
415 u_int deadline = 0, now = time(NULL);
416 Identity *id, *nxt;
417 int version;
418 Idtab *tab;
419
420 for (version = 1; version < 3; version++) {
421 tab = idtab_lookup(version);
422 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
423 nxt = TAILQ_NEXT(id, next);
424 if (id->death == 0)
425 continue;
426 if (now >= id->death) {
427 debug("expiring key '%s'", id->comment);
428 TAILQ_REMOVE(&tab->idlist, id, next);
429 free_identity(id);
430 tab->nentries--;
431 } else
432 deadline = (deadline == 0) ? id->death :
433 MIN(deadline, id->death);
434 }
435 }
436 if (deadline == 0 || deadline <= now)
437 return 0;
438 else
439 return (deadline - now);
440 }
441
442 static void
process_add_identity(SocketEntry * e,int version)443 process_add_identity(SocketEntry *e, int version)
444 {
445 Idtab *tab = idtab_lookup(version);
446 Identity *id;
447 int type, success = 0, death = 0, confirm = 0;
448 char *type_name, *comment;
449 Key *k = NULL;
450
451 switch (version) {
452 case 1:
453 k = key_new_private(KEY_RSA1);
454 (void) buffer_get_int(&e->request); /* ignored */
455 buffer_get_bignum(&e->request, k->rsa->n);
456 buffer_get_bignum(&e->request, k->rsa->e);
457 buffer_get_bignum(&e->request, k->rsa->d);
458 buffer_get_bignum(&e->request, k->rsa->iqmp);
459
460 /* SSH and SSL have p and q swapped */
461 buffer_get_bignum(&e->request, k->rsa->q); /* p */
462 buffer_get_bignum(&e->request, k->rsa->p); /* q */
463
464 /* Generate additional parameters */
465 rsa_generate_additional_parameters(k->rsa);
466 break;
467 case 2:
468 type_name = buffer_get_string(&e->request, NULL);
469 type = key_type_from_name(type_name);
470 xfree(type_name);
471 switch (type) {
472 case KEY_DSA:
473 k = key_new_private(type);
474 buffer_get_bignum2(&e->request, k->dsa->p);
475 buffer_get_bignum2(&e->request, k->dsa->q);
476 buffer_get_bignum2(&e->request, k->dsa->g);
477 buffer_get_bignum2(&e->request, k->dsa->pub_key);
478 buffer_get_bignum2(&e->request, k->dsa->priv_key);
479 break;
480 case KEY_RSA:
481 k = key_new_private(type);
482 buffer_get_bignum2(&e->request, k->rsa->n);
483 buffer_get_bignum2(&e->request, k->rsa->e);
484 buffer_get_bignum2(&e->request, k->rsa->d);
485 buffer_get_bignum2(&e->request, k->rsa->iqmp);
486 buffer_get_bignum2(&e->request, k->rsa->p);
487 buffer_get_bignum2(&e->request, k->rsa->q);
488
489 /* Generate additional parameters */
490 rsa_generate_additional_parameters(k->rsa);
491 break;
492 default:
493 buffer_clear(&e->request);
494 goto send;
495 }
496 break;
497 }
498 /* enable blinding */
499 switch (k->type) {
500 case KEY_RSA:
501 case KEY_RSA1:
502 if (RSA_blinding_on(k->rsa, NULL) != 1) {
503 error("process_add_identity: RSA_blinding_on failed");
504 key_free(k);
505 goto send;
506 }
507 break;
508 }
509 comment = buffer_get_string(&e->request, NULL);
510 if (k == NULL) {
511 xfree(comment);
512 goto send;
513 }
514 while (buffer_len(&e->request)) {
515 switch ((type = 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 error("process_add_identity: "
524 "Unknown constraint type %d", type);
525 xfree(comment);
526 key_free(k);
527 goto send;
528 }
529 }
530 success = 1;
531 if (lifetime && !death)
532 death = time(NULL) + lifetime;
533 if ((id = lookup_identity(k, version)) == NULL) {
534 id = xmalloc(sizeof(Identity));
535 id->key = k;
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(id->comment);
542 }
543 id->comment = comment;
544 id->death = death;
545 id->confirm = confirm;
546 send:
547 buffer_put_int(&e->output, 1);
548 buffer_put_char(&e->output,
549 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
550 }
551
552 /* XXX todo: encrypt sensitive data with passphrase */
553 static void
process_lock_agent(SocketEntry * e,int lock)554 process_lock_agent(SocketEntry *e, int lock)
555 {
556 int success = 0;
557 char *passwd;
558
559 passwd = buffer_get_string(&e->request, NULL);
560 if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
561 locked = 0;
562 memset(lock_passwd, 0, strlen(lock_passwd));
563 xfree(lock_passwd);
564 lock_passwd = NULL;
565 success = 1;
566 } else if (!locked && lock) {
567 locked = 1;
568 lock_passwd = xstrdup(passwd);
569 success = 1;
570 }
571 memset(passwd, 0, strlen(passwd));
572 xfree(passwd);
573
574 buffer_put_int(&e->output, 1);
575 buffer_put_char(&e->output,
576 success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
577 }
578
579 static void
no_identities(SocketEntry * e,u_int type)580 no_identities(SocketEntry *e, u_int type)
581 {
582 Buffer msg;
583
584 buffer_init(&msg);
585 buffer_put_char(&msg,
586 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
587 SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
588 buffer_put_int(&msg, 0);
589 buffer_put_int(&e->output, buffer_len(&msg));
590 buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
591 buffer_free(&msg);
592 }
593
594 /* dispatch incoming messages */
595
596 static void
process_message(SocketEntry * e)597 process_message(SocketEntry *e)
598 {
599 u_int msg_len, type;
600 u_char *cp;
601
602 if (buffer_len(&e->input) < 5)
603 return; /* Incomplete message. */
604 cp = buffer_ptr(&e->input);
605 msg_len = get_u32(cp);
606 if (msg_len > 256 * 1024) {
607 close_socket(e);
608 return;
609 }
610 if (buffer_len(&e->input) < msg_len + 4)
611 return;
612
613 /* move the current input to e->request */
614 buffer_consume(&e->input, 4);
615 buffer_clear(&e->request);
616 buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
617 buffer_consume(&e->input, msg_len);
618 type = buffer_get_char(&e->request);
619
620 /* check wheter agent is locked */
621 if (locked && type != SSH_AGENTC_UNLOCK) {
622 buffer_clear(&e->request);
623 switch (type) {
624 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
625 case SSH2_AGENTC_REQUEST_IDENTITIES:
626 /* send empty lists */
627 no_identities(e, type);
628 break;
629 default:
630 /* send a fail message for all other request types */
631 buffer_put_int(&e->output, 1);
632 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
633 }
634 return;
635 }
636
637 debug("type %d", type);
638 switch (type) {
639 case SSH_AGENTC_LOCK:
640 case SSH_AGENTC_UNLOCK:
641 process_lock_agent(e, type == SSH_AGENTC_LOCK);
642 break;
643 /* ssh1 */
644 case SSH_AGENTC_RSA_CHALLENGE:
645 process_authentication_challenge1(e);
646 break;
647 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
648 process_request_identities(e, 1);
649 break;
650 case SSH_AGENTC_ADD_RSA_IDENTITY:
651 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
652 process_add_identity(e, 1);
653 break;
654 case SSH_AGENTC_REMOVE_RSA_IDENTITY:
655 process_remove_identity(e, 1);
656 break;
657 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
658 process_remove_all_identities(e, 1);
659 break;
660 /* ssh2 */
661 case SSH2_AGENTC_SIGN_REQUEST:
662 process_sign_request2(e);
663 break;
664 case SSH2_AGENTC_REQUEST_IDENTITIES:
665 process_request_identities(e, 2);
666 break;
667 case SSH2_AGENTC_ADD_IDENTITY:
668 case SSH2_AGENTC_ADD_ID_CONSTRAINED:
669 process_add_identity(e, 2);
670 break;
671 case SSH2_AGENTC_REMOVE_IDENTITY:
672 process_remove_identity(e, 2);
673 break;
674 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
675 process_remove_all_identities(e, 2);
676 break;
677 default:
678 /* Unknown message. Respond with failure. */
679 error("Unknown message %d", type);
680 buffer_clear(&e->request);
681 buffer_put_int(&e->output, 1);
682 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
683 break;
684 }
685 }
686
687 static void
new_socket(sock_type type,int fd)688 new_socket(sock_type type, int fd)
689 {
690 u_int i, old_alloc, new_alloc;
691
692 set_nonblock(fd);
693
694 if (fd > max_fd)
695 max_fd = fd;
696
697 for (i = 0; i < sockets_alloc; i++)
698 if (sockets[i].type == AUTH_UNUSED) {
699 sockets[i].fd = fd;
700 buffer_init(&sockets[i].input);
701 buffer_init(&sockets[i].output);
702 buffer_init(&sockets[i].request);
703 sockets[i].type = type;
704 return;
705 }
706 old_alloc = sockets_alloc;
707 new_alloc = sockets_alloc + 10;
708 sockets = xrealloc(sockets, new_alloc * sizeof(sockets[0]));
709 for (i = old_alloc; i < new_alloc; i++)
710 sockets[i].type = AUTH_UNUSED;
711 sockets_alloc = new_alloc;
712 sockets[old_alloc].fd = fd;
713 buffer_init(&sockets[old_alloc].input);
714 buffer_init(&sockets[old_alloc].output);
715 buffer_init(&sockets[old_alloc].request);
716 sockets[old_alloc].type = type;
717 }
718
719 static int
prepare_select(fd_set ** fdrp,fd_set ** fdwp,int * fdl,u_int * nallocp,struct timeval ** tvpp)720 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
721 struct timeval **tvpp)
722 {
723 u_int i, sz, deadline;
724 int n = 0;
725 static struct timeval tv;
726
727 for (i = 0; i < sockets_alloc; i++) {
728 switch (sockets[i].type) {
729 case AUTH_SOCKET:
730 case AUTH_CONNECTION:
731 n = MAX(n, sockets[i].fd);
732 break;
733 case AUTH_UNUSED:
734 break;
735 default:
736 fatal("Unknown socket type %d", sockets[i].type);
737 break;
738 }
739 }
740
741 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
742 if (*fdrp == NULL || sz > *nallocp) {
743 if (*fdrp)
744 xfree(*fdrp);
745 if (*fdwp)
746 xfree(*fdwp);
747 *fdrp = xmalloc(sz);
748 *fdwp = xmalloc(sz);
749 *nallocp = sz;
750 }
751 if (n < *fdl)
752 debug("XXX shrink: %d < %d", n, *fdl);
753 *fdl = n;
754 memset(*fdrp, 0, sz);
755 memset(*fdwp, 0, sz);
756
757 for (i = 0; i < sockets_alloc; i++) {
758 switch (sockets[i].type) {
759 case AUTH_SOCKET:
760 case AUTH_CONNECTION:
761 FD_SET(sockets[i].fd, *fdrp);
762 if (buffer_len(&sockets[i].output) > 0)
763 FD_SET(sockets[i].fd, *fdwp);
764 break;
765 default:
766 break;
767 }
768 }
769 deadline = reaper();
770 if (parent_alive_interval != 0)
771 deadline = (deadline == 0) ? parent_alive_interval :
772 MIN(deadline, parent_alive_interval);
773 if (deadline == 0) {
774 *tvpp = NULL;
775 } else {
776 tv.tv_sec = deadline;
777 tv.tv_usec = 0;
778 *tvpp = &tv;
779 }
780 return (1);
781 }
782
783 static void
after_select(fd_set * readset,fd_set * writeset)784 after_select(fd_set *readset, fd_set *writeset)
785 {
786 struct sockaddr_un sunaddr;
787 socklen_t slen;
788 char buf[1024];
789 int len, sock;
790 u_int i;
791 uid_t euid;
792 gid_t egid;
793
794 for (i = 0; i < sockets_alloc; i++)
795 switch (sockets[i].type) {
796 case AUTH_UNUSED:
797 break;
798 case AUTH_SOCKET:
799 if (FD_ISSET(sockets[i].fd, readset)) {
800 slen = sizeof(sunaddr);
801 sock = accept(sockets[i].fd,
802 (struct sockaddr *)&sunaddr, &slen);
803 if (sock < 0) {
804 error("accept from AUTH_SOCKET: %s",
805 strerror(errno));
806 break;
807 }
808 if (getpeereid(sock, &euid, &egid) < 0) {
809 error("getpeereid %d failed: %s",
810 sock, strerror(errno));
811 close(sock);
812 break;
813 }
814 if ((euid != 0) && (getuid() != euid)) {
815 error("uid mismatch: "
816 "peer euid %u != uid %u",
817 (u_int) euid, (u_int) getuid());
818 close(sock);
819 break;
820 }
821 new_socket(AUTH_CONNECTION, sock);
822 }
823 break;
824 case AUTH_CONNECTION:
825 if (buffer_len(&sockets[i].output) > 0 &&
826 FD_ISSET(sockets[i].fd, writeset)) {
827 do {
828 len = write(sockets[i].fd,
829 buffer_ptr(&sockets[i].output),
830 buffer_len(&sockets[i].output));
831 if (len == -1 && (errno == EAGAIN ||
832 errno == EINTR ||
833 errno == EWOULDBLOCK))
834 continue;
835 break;
836 } while (1);
837 if (len <= 0) {
838 close_socket(&sockets[i]);
839 break;
840 }
841 buffer_consume(&sockets[i].output, len);
842 }
843 if (FD_ISSET(sockets[i].fd, readset)) {
844 do {
845 len = read(sockets[i].fd, buf, sizeof(buf));
846 if (len == -1 && (errno == EAGAIN ||
847 errno == EINTR ||
848 errno == EWOULDBLOCK))
849 continue;
850 break;
851 } while (1);
852 if (len <= 0) {
853 close_socket(&sockets[i]);
854 break;
855 }
856 buffer_append(&sockets[i].input, buf, len);
857 process_message(&sockets[i]);
858 }
859 break;
860 default:
861 fatal("Unknown type %d", sockets[i].type);
862 }
863 }
864
865 static void
cleanup_socket(void)866 cleanup_socket(void)
867 {
868 if (socket_name[0])
869 unlink(socket_name);
870 if (socket_dir[0])
871 rmdir(socket_dir);
872 }
873
874 void
cleanup_exit(int i)875 cleanup_exit(int i)
876 {
877 cleanup_socket();
878 _exit(i);
879 }
880
881 /*ARGSUSED*/
882 static void
cleanup_handler(int sig)883 cleanup_handler(int sig)
884 {
885 cleanup_socket();
886 _exit(2);
887 }
888
889 static void
check_parent_exists(void)890 check_parent_exists(void)
891 {
892 #ifdef HAVE_SOLARIS_PRIVILEGE
893 /*
894 * We can not simply use "kill(ppid, 0) < 0" to detect if the parent
895 * has exited when the child process no longer has the
896 * PRIV_PROC_SESSION privilege.
897 */
898 if (parent_pid != -1 && getppid() != parent_pid) {
899 #else
900 if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
901
902 #endif
903 /* printf("Parent has died - Authentication agent exiting.\n"); */
904 cleanup_socket();
905 _exit(2);
906 }
907 }
908
909 static void
910 usage(void)
911 {
912 fprintf(stderr,
913 gettext("Usage: %s [options] [command [args ...]]\n"
914 "Options:\n"
915 " -c Generate C-shell commands on stdout.\n"
916 " -s Generate Bourne shell commands on stdout.\n"
917 " -k Kill the current agent.\n"
918 " -d Debug mode.\n"
919 " -a socket Bind agent socket to given name.\n"
920 " -t life Default identity lifetime (seconds).\n"),
921 __progname);
922 exit(1);
923 }
924
925 int
926 main(int ac, char **av)
927 {
928 int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
929 int sock, fd, ch, result, saved_errno;
930 u_int nalloc;
931 char *shell, *pidstr, *agentsocket = NULL;
932 const char *format;
933 fd_set *readsetp = NULL, *writesetp = NULL;
934 struct sockaddr_un sunaddr;
935 #ifdef HAVE_SETRLIMIT
936 struct rlimit rlim;
937 #endif
938 int prev_mask;
939 extern int optind;
940 extern char *optarg;
941 pid_t pid;
942 char pidstrbuf[1 + 3 * sizeof pid];
943 struct timeval *tvp = NULL;
944 #ifdef HAVE_SOLARIS_PRIVILEGE
945 priv_set_t *myprivs;
946 #endif /* HAVE_SOLARIS_PRIVILEGE */
947
948 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
949 sanitise_stdfd();
950
951 /* drop */
952 setegid(getgid());
953 setgid(getgid());
954
955 SSLeay_add_all_algorithms();
956
957 __progname = get_progname(av[0]);
958 init_rng();
959 seed_rng();
960
961 while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
962 switch (ch) {
963 case 'c':
964 if (s_flag)
965 usage();
966 c_flag++;
967 break;
968 case 'k':
969 k_flag++;
970 break;
971 case 's':
972 if (c_flag)
973 usage();
974 s_flag++;
975 break;
976 case 'd':
977 if (d_flag)
978 usage();
979 d_flag++;
980 break;
981 case 'a':
982 agentsocket = optarg;
983 break;
984 case 't':
985 if ((lifetime = convtime(optarg)) == -1) {
986 fprintf(stderr, gettext("Invalid lifetime\n"));
987 usage();
988 }
989 break;
990 default:
991 usage();
992 }
993 }
994 ac -= optind;
995 av += optind;
996
997 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
998 usage();
999
1000 if (ac == 0 && !c_flag && !s_flag) {
1001 shell = getenv("SHELL");
1002 if (shell != NULL &&
1003 strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1004 c_flag = 1;
1005 }
1006 if (k_flag) {
1007 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1008 if (pidstr == NULL) {
1009 fprintf(stderr,
1010 gettext("%s not set, cannot kill agent\n"),
1011 SSH_AGENTPID_ENV_NAME);
1012 exit(1);
1013 }
1014 pid = atoi(pidstr);
1015 if (pid < 1) {
1016 fprintf(stderr,
1017 gettext("%s not set, cannot kill agent\n"),
1018 SSH_AGENTPID_ENV_NAME);
1019 exit(1);
1020 }
1021 if (kill(pid, SIGTERM) == -1) {
1022 perror("kill");
1023 exit(1);
1024 }
1025 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1026 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1027 printf(format, SSH_AGENTPID_ENV_NAME);
1028 printf("echo ");
1029 printf(gettext("Agent pid %ld killed;\n"), (long)pid);
1030 exit(0);
1031 }
1032 parent_pid = getpid();
1033
1034 if (agentsocket == NULL) {
1035 /* Create private directory for agent socket */
1036 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1037 if (mkdtemp(socket_dir) == NULL) {
1038 perror("mkdtemp: private socket dir");
1039 exit(1);
1040 }
1041 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1042 (long)parent_pid);
1043 } else {
1044 /* Try to use specified agent socket */
1045 socket_dir[0] = '\0';
1046 strlcpy(socket_name, agentsocket, sizeof socket_name);
1047 }
1048
1049 /*
1050 * Create socket early so it will exist before command gets run from
1051 * the parent.
1052 */
1053 sock = socket(AF_UNIX, SOCK_STREAM, 0);
1054 if (sock < 0) {
1055 perror("socket");
1056 *socket_name = '\0'; /* Don't unlink any existing file */
1057 cleanup_exit(1);
1058 }
1059 memset(&sunaddr, 0, sizeof(sunaddr));
1060 sunaddr.sun_family = AF_UNIX;
1061 strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1062 prev_mask = umask(0177);
1063 if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1064 perror("bind");
1065 *socket_name = '\0'; /* Don't unlink any existing file */
1066 umask(prev_mask);
1067 cleanup_exit(1);
1068 }
1069 umask(prev_mask);
1070 if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1071 perror("listen");
1072 cleanup_exit(1);
1073 }
1074
1075 /*
1076 * Fork, and have the parent execute the command, if any, or present
1077 * the socket data. The child continues as the authentication agent.
1078 */
1079 if (d_flag) {
1080 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1081 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1082 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1083 SSH_AUTHSOCKET_ENV_NAME);
1084 printf("echo ");
1085 printf(gettext("Agent pid %ld;\n"), (long)parent_pid);
1086 goto skip;
1087 }
1088 pid = fork();
1089 if (pid == -1) {
1090 perror("fork");
1091 cleanup_exit(1);
1092 }
1093 if (pid != 0) { /* Parent - execute the given command. */
1094 close(sock);
1095 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1096 if (ac == 0) {
1097 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1098 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1099 SSH_AUTHSOCKET_ENV_NAME);
1100 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1101 SSH_AGENTPID_ENV_NAME);
1102 printf("echo ");
1103 printf(gettext("Agent pid %ld;\n"), (long)pid);
1104 exit(0);
1105 }
1106 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1107 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1108 perror("setenv");
1109 exit(1);
1110 }
1111 execvp(av[0], av);
1112 perror(av[0]);
1113 exit(1);
1114 }
1115 /* child */
1116 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1117
1118 #ifdef HAVE_SOLARIS_PRIVILEGE
1119 /*
1120 * Drop unneeded privs, including basic ones like fork/exec.
1121 *
1122 * Idiom: remove from 'basic' privs we know we don't want,
1123 * invert the result and remove the resulting set from P.
1124 *
1125 * None of the priv_delset() calls below, nor the setppriv call
1126 * below can fail, so their return values are not checked.
1127 */
1128 if ((myprivs = priv_str_to_set("basic", ",", NULL)) == NULL)
1129 fatal("priv_str_to_set failed: %m");
1130 (void) priv_delset(myprivs, PRIV_PROC_EXEC);
1131 (void) priv_delset(myprivs, PRIV_PROC_FORK);
1132 (void) priv_delset(myprivs, PRIV_FILE_LINK_ANY);
1133 (void) priv_delset(myprivs, PRIV_PROC_INFO);
1134 (void) priv_delset(myprivs, PRIV_PROC_SESSION);
1135 priv_inverse(myprivs);
1136 (void) setppriv(PRIV_OFF, PRIV_PERMITTED, myprivs);
1137 (void) priv_freeset(myprivs);
1138 #endif /* HAVE_SOLARIS_PRIVILEGE */
1139
1140 if (setsid() == -1) {
1141 error("setsid: %s", strerror(errno));
1142 cleanup_exit(1);
1143 }
1144
1145 (void)chdir("/");
1146 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1147 /* XXX might close listen socket */
1148 (void)dup2(fd, STDIN_FILENO);
1149 (void)dup2(fd, STDOUT_FILENO);
1150 (void)dup2(fd, STDERR_FILENO);
1151 if (fd > 2)
1152 close(fd);
1153 }
1154
1155 #ifdef HAVE_SETRLIMIT
1156 /* deny core dumps, since memory contains unencrypted private keys */
1157 rlim.rlim_cur = rlim.rlim_max = 0;
1158 if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1159 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1160 cleanup_exit(1);
1161 }
1162 #endif
1163
1164 skip:
1165 new_socket(AUTH_SOCKET, sock);
1166 if (ac > 0)
1167 parent_alive_interval = 10;
1168 idtab_init();
1169 if (!d_flag)
1170 signal(SIGINT, SIG_IGN);
1171 signal(SIGPIPE, SIG_IGN);
1172 signal(SIGHUP, cleanup_handler);
1173 signal(SIGTERM, cleanup_handler);
1174 nalloc = 0;
1175
1176 while (1) {
1177 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1178 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1179 saved_errno = errno;
1180 if (parent_alive_interval != 0)
1181 check_parent_exists();
1182 (void) reaper(); /* remove expired keys */
1183 if (result < 0) {
1184 if (saved_errno == EINTR)
1185 continue;
1186 fatal("select: %s", strerror(saved_errno));
1187 } else if (result > 0)
1188 after_select(readsetp, writesetp);
1189 }
1190 /* NOTREACHED */
1191 return (0); /* keep lint happy */
1192 }
1193