1 /* $OpenBSD: ssh-agent.c,v 1.204 2015/07/08 20:24:02 markus 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/param.h> /* MIN MAX */
40 #include <sys/types.h>
41 #include <sys/param.h>
42 #include <sys/resource.h>
43 #include <sys/stat.h>
44 #include <sys/socket.h>
45 #ifdef HAVE_SYS_TIME_H
46 # include <sys/time.h>
47 #endif
48 #ifdef HAVE_SYS_UN_H
49 # include <sys/un.h>
50 #endif
51 #include "openbsd-compat/sys-queue.h"
52
53 #ifdef WITH_OPENSSL
54 #include <openssl/evp.h>
55 #include "openbsd-compat/openssl-compat.h"
56 #endif
57
58 #include <errno.h>
59 #include <fcntl.h>
60 #include <limits.h>
61 #ifdef HAVE_PATHS_H
62 # include <paths.h>
63 #endif
64 #include <signal.h>
65 #include <stdarg.h>
66 #include <stdio.h>
67 #include <stdlib.h>
68 #include <time.h>
69 #include <string.h>
70 #include <unistd.h>
71 #ifdef HAVE_UTIL_H
72 # include <util.h>
73 #endif
74
75 #include "xmalloc.h"
76 #include "ssh.h"
77 #include "rsa.h"
78 #include "sshbuf.h"
79 #include "sshkey.h"
80 #include "authfd.h"
81 #include "compat.h"
82 #include "log.h"
83 #include "misc.h"
84 #include "digest.h"
85 #include "ssherr.h"
86
87 #ifdef ENABLE_PKCS11
88 #include "ssh-pkcs11.h"
89 #endif
90
91 #if defined(HAVE_SYS_PRCTL_H)
92 #include <sys/prctl.h> /* For prctl() and PR_SET_DUMPABLE */
93 #endif
94
95 typedef enum {
96 AUTH_UNUSED,
97 AUTH_SOCKET,
98 AUTH_CONNECTION
99 } sock_type;
100
101 typedef struct {
102 int fd;
103 sock_type type;
104 struct sshbuf *input;
105 struct sshbuf *output;
106 struct sshbuf *request;
107 } SocketEntry;
108
109 u_int sockets_alloc = 0;
110 SocketEntry *sockets = NULL;
111
112 typedef struct identity {
113 TAILQ_ENTRY(identity) next;
114 struct sshkey *key;
115 char *comment;
116 char *provider;
117 time_t death;
118 u_int confirm;
119 } Identity;
120
121 typedef struct {
122 int nentries;
123 TAILQ_HEAD(idqueue, identity) idlist;
124 } Idtab;
125
126 /* private key table, one per protocol version */
127 Idtab idtable[3];
128
129 int max_fd = 0;
130
131 /* pid of shell == parent of agent */
132 pid_t parent_pid = -1;
133 time_t parent_alive_interval = 0;
134
135 /* pid of process for which cleanup_socket is applicable */
136 pid_t cleanup_pid = 0;
137
138 /* pathname and directory for AUTH_SOCKET */
139 char socket_name[PATH_MAX];
140 char socket_dir[PATH_MAX];
141
142 /* locking */
143 #define LOCK_SIZE 32
144 #define LOCK_SALT_SIZE 16
145 #define LOCK_ROUNDS 1
146 int locked = 0;
147 char lock_passwd[LOCK_SIZE];
148 char lock_salt[LOCK_SALT_SIZE];
149
150 extern char *__progname;
151
152 /* Default lifetime in seconds (0 == forever) */
153 static long lifetime = 0;
154
155 static int fingerprint_hash = SSH_FP_HASH_DEFAULT;
156
157 static void
close_socket(SocketEntry * e)158 close_socket(SocketEntry *e)
159 {
160 close(e->fd);
161 e->fd = -1;
162 e->type = AUTH_UNUSED;
163 sshbuf_free(e->input);
164 sshbuf_free(e->output);
165 sshbuf_free(e->request);
166 }
167
168 static void
idtab_init(void)169 idtab_init(void)
170 {
171 int i;
172
173 for (i = 0; i <=2; i++) {
174 TAILQ_INIT(&idtable[i].idlist);
175 idtable[i].nentries = 0;
176 }
177 }
178
179 /* return private key table for requested protocol version */
180 static Idtab *
idtab_lookup(int version)181 idtab_lookup(int version)
182 {
183 if (version < 1 || version > 2)
184 fatal("internal error, bad protocol version %d", version);
185 return &idtable[version];
186 }
187
188 static void
free_identity(Identity * id)189 free_identity(Identity *id)
190 {
191 sshkey_free(id->key);
192 free(id->provider);
193 free(id->comment);
194 free(id);
195 }
196
197 /* return matching private key for given public key */
198 static Identity *
lookup_identity(struct sshkey * key,int version)199 lookup_identity(struct sshkey *key, int version)
200 {
201 Identity *id;
202
203 Idtab *tab = idtab_lookup(version);
204 TAILQ_FOREACH(id, &tab->idlist, next) {
205 if (sshkey_equal(key, id->key))
206 return (id);
207 }
208 return (NULL);
209 }
210
211 /* Check confirmation of keysign request */
212 static int
confirm_key(Identity * id)213 confirm_key(Identity *id)
214 {
215 char *p;
216 int ret = -1;
217
218 p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT);
219 if (p != NULL &&
220 ask_permission("Allow use of key %s?\nKey fingerprint %s.",
221 id->comment, p))
222 ret = 0;
223 free(p);
224
225 return (ret);
226 }
227
228 static void
send_status(SocketEntry * e,int success)229 send_status(SocketEntry *e, int success)
230 {
231 int r;
232
233 if ((r = sshbuf_put_u32(e->output, 1)) != 0 ||
234 (r = sshbuf_put_u8(e->output, success ?
235 SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0)
236 fatal("%s: buffer error: %s", __func__, ssh_err(r));
237 }
238
239 /* send list of supported public keys to 'client' */
240 static void
process_request_identities(SocketEntry * e,int version)241 process_request_identities(SocketEntry *e, int version)
242 {
243 Idtab *tab = idtab_lookup(version);
244 Identity *id;
245 struct sshbuf *msg;
246 int r;
247
248 if ((msg = sshbuf_new()) == NULL)
249 fatal("%s: sshbuf_new failed", __func__);
250 if ((r = sshbuf_put_u8(msg, (version == 1) ?
251 SSH_AGENT_RSA_IDENTITIES_ANSWER :
252 SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
253 (r = sshbuf_put_u32(msg, tab->nentries)) != 0)
254 fatal("%s: buffer error: %s", __func__, ssh_err(r));
255 TAILQ_FOREACH(id, &tab->idlist, next) {
256 if (id->key->type == KEY_RSA1) {
257 #ifdef WITH_SSH1
258 if ((r = sshbuf_put_u32(msg,
259 BN_num_bits(id->key->rsa->n))) != 0 ||
260 (r = sshbuf_put_bignum1(msg,
261 id->key->rsa->e)) != 0 ||
262 (r = sshbuf_put_bignum1(msg,
263 id->key->rsa->n)) != 0)
264 fatal("%s: buffer error: %s",
265 __func__, ssh_err(r));
266 #endif
267 } else {
268 u_char *blob;
269 size_t blen;
270
271 if ((r = sshkey_to_blob(id->key, &blob, &blen)) != 0) {
272 error("%s: sshkey_to_blob: %s", __func__,
273 ssh_err(r));
274 continue;
275 }
276 if ((r = sshbuf_put_string(msg, blob, blen)) != 0)
277 fatal("%s: buffer error: %s",
278 __func__, ssh_err(r));
279 free(blob);
280 }
281 if ((r = sshbuf_put_cstring(msg, id->comment)) != 0)
282 fatal("%s: buffer error: %s", __func__, ssh_err(r));
283 }
284 if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
285 fatal("%s: buffer error: %s", __func__, ssh_err(r));
286 sshbuf_free(msg);
287 }
288
289 #ifdef WITH_SSH1
290 /* ssh1 only */
291 static void
process_authentication_challenge1(SocketEntry * e)292 process_authentication_challenge1(SocketEntry *e)
293 {
294 u_char buf[32], mdbuf[16], session_id[16];
295 u_int response_type;
296 BIGNUM *challenge;
297 Identity *id;
298 int r, len;
299 struct sshbuf *msg;
300 struct ssh_digest_ctx *md;
301 struct sshkey *key;
302
303 if ((msg = sshbuf_new()) == NULL)
304 fatal("%s: sshbuf_new failed", __func__);
305 if ((key = sshkey_new(KEY_RSA1)) == NULL)
306 fatal("%s: sshkey_new failed", __func__);
307 if ((challenge = BN_new()) == NULL)
308 fatal("%s: BN_new failed", __func__);
309
310 if ((r = sshbuf_get_u32(e->request, NULL)) != 0 || /* ignored */
311 (r = sshbuf_get_bignum1(e->request, key->rsa->e)) != 0 ||
312 (r = sshbuf_get_bignum1(e->request, key->rsa->n)) != 0 ||
313 (r = sshbuf_get_bignum1(e->request, challenge)))
314 fatal("%s: buffer error: %s", __func__, ssh_err(r));
315
316 /* Only protocol 1.1 is supported */
317 if (sshbuf_len(e->request) == 0)
318 goto failure;
319 if ((r = sshbuf_get(e->request, session_id, sizeof(session_id))) != 0 ||
320 (r = sshbuf_get_u32(e->request, &response_type)) != 0)
321 fatal("%s: buffer error: %s", __func__, ssh_err(r));
322 if (response_type != 1)
323 goto failure;
324
325 id = lookup_identity(key, 1);
326 if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
327 struct sshkey *private = id->key;
328 /* Decrypt the challenge using the private key. */
329 if ((r = rsa_private_decrypt(challenge, challenge,
330 private->rsa) != 0)) {
331 fatal("%s: rsa_public_encrypt: %s", __func__,
332 ssh_err(r));
333 goto failure; /* XXX ? */
334 }
335
336 /* The response is MD5 of decrypted challenge plus session id */
337 len = BN_num_bytes(challenge);
338 if (len <= 0 || len > 32) {
339 logit("%s: bad challenge length %d", __func__, len);
340 goto failure;
341 }
342 memset(buf, 0, 32);
343 BN_bn2bin(challenge, buf + 32 - len);
344 if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
345 ssh_digest_update(md, buf, 32) < 0 ||
346 ssh_digest_update(md, session_id, 16) < 0 ||
347 ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0)
348 fatal("%s: md5 failed", __func__);
349 ssh_digest_free(md);
350
351 /* Send the response. */
352 if ((r = sshbuf_put_u8(msg, SSH_AGENT_RSA_RESPONSE)) != 0 ||
353 (r = sshbuf_put(msg, mdbuf, sizeof(mdbuf))) != 0)
354 fatal("%s: buffer error: %s", __func__, ssh_err(r));
355 goto send;
356 }
357
358 failure:
359 /* Unknown identity or protocol error. Send failure. */
360 if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
361 fatal("%s: buffer error: %s", __func__, ssh_err(r));
362 send:
363 if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
364 fatal("%s: buffer error: %s", __func__, ssh_err(r));
365 sshkey_free(key);
366 BN_clear_free(challenge);
367 sshbuf_free(msg);
368 }
369 #endif
370
371 /* ssh2 only */
372 static void
process_sign_request2(SocketEntry * e)373 process_sign_request2(SocketEntry *e)
374 {
375 u_char *blob, *data, *signature = NULL;
376 size_t blen, dlen, slen = 0;
377 u_int compat = 0, flags;
378 int r, ok = -1;
379 struct sshbuf *msg;
380 struct sshkey *key;
381 struct identity *id;
382
383 if ((msg = sshbuf_new()) == NULL)
384 fatal("%s: sshbuf_new failed", __func__);
385 if ((r = sshbuf_get_string(e->request, &blob, &blen)) != 0 ||
386 (r = sshbuf_get_string(e->request, &data, &dlen)) != 0 ||
387 (r = sshbuf_get_u32(e->request, &flags)) != 0)
388 fatal("%s: buffer error: %s", __func__, ssh_err(r));
389 if (flags & SSH_AGENT_OLD_SIGNATURE)
390 compat = SSH_BUG_SIGBLOB;
391 if ((r = sshkey_from_blob(blob, blen, &key)) != 0) {
392 error("%s: cannot parse key blob: %s", __func__, ssh_err(ok));
393 goto send;
394 }
395 if ((id = lookup_identity(key, 2)) == NULL) {
396 verbose("%s: %s key not found", __func__, sshkey_type(key));
397 goto send;
398 }
399 if (id->confirm && confirm_key(id) != 0) {
400 verbose("%s: user refused key", __func__);
401 goto send;
402 }
403 if ((r = sshkey_sign(id->key, &signature, &slen,
404 data, dlen, compat)) != 0) {
405 error("%s: sshkey_sign: %s", __func__, ssh_err(ok));
406 goto send;
407 }
408 /* Success */
409 ok = 0;
410 send:
411 sshkey_free(key);
412 if (ok == 0) {
413 if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 ||
414 (r = sshbuf_put_string(msg, signature, slen)) != 0)
415 fatal("%s: buffer error: %s", __func__, ssh_err(r));
416 } else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
417 fatal("%s: buffer error: %s", __func__, ssh_err(r));
418
419 if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
420 fatal("%s: buffer error: %s", __func__, ssh_err(r));
421
422 sshbuf_free(msg);
423 free(data);
424 free(blob);
425 free(signature);
426 }
427
428 /* shared */
429 static void
process_remove_identity(SocketEntry * e,int version)430 process_remove_identity(SocketEntry *e, int version)
431 {
432 size_t blen;
433 int r, success = 0;
434 struct sshkey *key = NULL;
435 u_char *blob;
436 #ifdef WITH_SSH1
437 u_int bits;
438 #endif /* WITH_SSH1 */
439
440 switch (version) {
441 #ifdef WITH_SSH1
442 case 1:
443 if ((key = sshkey_new(KEY_RSA1)) == NULL) {
444 error("%s: sshkey_new failed", __func__);
445 return;
446 }
447 if ((r = sshbuf_get_u32(e->request, &bits)) != 0 ||
448 (r = sshbuf_get_bignum1(e->request, key->rsa->e)) != 0 ||
449 (r = sshbuf_get_bignum1(e->request, key->rsa->n)) != 0)
450 fatal("%s: buffer error: %s", __func__, ssh_err(r));
451
452 if (bits != sshkey_size(key))
453 logit("Warning: identity keysize mismatch: "
454 "actual %u, announced %u",
455 sshkey_size(key), bits);
456 break;
457 #endif /* WITH_SSH1 */
458 case 2:
459 if ((r = sshbuf_get_string(e->request, &blob, &blen)) != 0)
460 fatal("%s: buffer error: %s", __func__, ssh_err(r));
461 if ((r = sshkey_from_blob(blob, blen, &key)) != 0)
462 error("%s: sshkey_from_blob failed: %s",
463 __func__, ssh_err(r));
464 free(blob);
465 break;
466 }
467 if (key != NULL) {
468 Identity *id = lookup_identity(key, version);
469 if (id != NULL) {
470 /*
471 * We have this key. Free the old key. Since we
472 * don't want to leave empty slots in the middle of
473 * the array, we actually free the key there and move
474 * all the entries between the empty slot and the end
475 * of the array.
476 */
477 Idtab *tab = idtab_lookup(version);
478 if (tab->nentries < 1)
479 fatal("process_remove_identity: "
480 "internal error: tab->nentries %d",
481 tab->nentries);
482 TAILQ_REMOVE(&tab->idlist, id, next);
483 free_identity(id);
484 tab->nentries--;
485 success = 1;
486 }
487 sshkey_free(key);
488 }
489 send_status(e, success);
490 }
491
492 static void
process_remove_all_identities(SocketEntry * e,int version)493 process_remove_all_identities(SocketEntry *e, int version)
494 {
495 Idtab *tab = idtab_lookup(version);
496 Identity *id;
497
498 /* Loop over all identities and clear the keys. */
499 for (id = TAILQ_FIRST(&tab->idlist); id;
500 id = TAILQ_FIRST(&tab->idlist)) {
501 TAILQ_REMOVE(&tab->idlist, id, next);
502 free_identity(id);
503 }
504
505 /* Mark that there are no identities. */
506 tab->nentries = 0;
507
508 /* Send success. */
509 send_status(e, 1);
510 }
511
512 /* removes expired keys and returns number of seconds until the next expiry */
513 static time_t
reaper(void)514 reaper(void)
515 {
516 time_t deadline = 0, now = monotime();
517 Identity *id, *nxt;
518 int version;
519 Idtab *tab;
520
521 for (version = 1; version < 3; version++) {
522 tab = idtab_lookup(version);
523 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
524 nxt = TAILQ_NEXT(id, next);
525 if (id->death == 0)
526 continue;
527 if (now >= id->death) {
528 debug("expiring key '%s'", id->comment);
529 TAILQ_REMOVE(&tab->idlist, id, next);
530 free_identity(id);
531 tab->nentries--;
532 } else
533 deadline = (deadline == 0) ? id->death :
534 MIN(deadline, id->death);
535 }
536 }
537 if (deadline == 0 || deadline <= now)
538 return 0;
539 else
540 return (deadline - now);
541 }
542
543 /*
544 * XXX this and the corresponding serialisation function probably belongs
545 * in key.c
546 */
547 #ifdef WITH_SSH1
548 static int
agent_decode_rsa1(struct sshbuf * m,struct sshkey ** kp)549 agent_decode_rsa1(struct sshbuf *m, struct sshkey **kp)
550 {
551 struct sshkey *k = NULL;
552 int r = SSH_ERR_INTERNAL_ERROR;
553
554 *kp = NULL;
555 if ((k = sshkey_new_private(KEY_RSA1)) == NULL)
556 return SSH_ERR_ALLOC_FAIL;
557
558 if ((r = sshbuf_get_u32(m, NULL)) != 0 || /* ignored */
559 (r = sshbuf_get_bignum1(m, k->rsa->n)) != 0 ||
560 (r = sshbuf_get_bignum1(m, k->rsa->e)) != 0 ||
561 (r = sshbuf_get_bignum1(m, k->rsa->d)) != 0 ||
562 (r = sshbuf_get_bignum1(m, k->rsa->iqmp)) != 0 ||
563 /* SSH1 and SSL have p and q swapped */
564 (r = sshbuf_get_bignum1(m, k->rsa->q)) != 0 || /* p */
565 (r = sshbuf_get_bignum1(m, k->rsa->p)) != 0) /* q */
566 goto out;
567
568 /* Generate additional parameters */
569 if ((r = rsa_generate_additional_parameters(k->rsa)) != 0)
570 goto out;
571 /* enable blinding */
572 if (RSA_blinding_on(k->rsa, NULL) != 1) {
573 r = SSH_ERR_LIBCRYPTO_ERROR;
574 goto out;
575 }
576
577 r = 0; /* success */
578 out:
579 if (r == 0)
580 *kp = k;
581 else
582 sshkey_free(k);
583 return r;
584 }
585 #endif /* WITH_SSH1 */
586
587 static void
process_add_identity(SocketEntry * e,int version)588 process_add_identity(SocketEntry *e, int version)
589 {
590 Idtab *tab = idtab_lookup(version);
591 Identity *id;
592 int success = 0, confirm = 0;
593 u_int seconds;
594 char *comment = NULL;
595 time_t death = 0;
596 struct sshkey *k = NULL;
597 u_char ctype;
598 int r = SSH_ERR_INTERNAL_ERROR;
599
600 switch (version) {
601 #ifdef WITH_SSH1
602 case 1:
603 r = agent_decode_rsa1(e->request, &k);
604 break;
605 #endif /* WITH_SSH1 */
606 case 2:
607 r = sshkey_private_deserialize(e->request, &k);
608 break;
609 }
610 if (r != 0 || k == NULL ||
611 (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) {
612 error("%s: decode private key: %s", __func__, ssh_err(r));
613 goto err;
614 }
615
616 while (sshbuf_len(e->request)) {
617 if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) {
618 error("%s: buffer error: %s", __func__, ssh_err(r));
619 goto err;
620 }
621 switch (ctype) {
622 case SSH_AGENT_CONSTRAIN_LIFETIME:
623 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) {
624 error("%s: bad lifetime constraint: %s",
625 __func__, ssh_err(r));
626 goto err;
627 }
628 death = monotime() + seconds;
629 break;
630 case SSH_AGENT_CONSTRAIN_CONFIRM:
631 confirm = 1;
632 break;
633 default:
634 error("%s: Unknown constraint %d", __func__, ctype);
635 err:
636 sshbuf_reset(e->request);
637 free(comment);
638 sshkey_free(k);
639 goto send;
640 }
641 }
642
643 success = 1;
644 if (lifetime && !death)
645 death = monotime() + lifetime;
646 if ((id = lookup_identity(k, version)) == NULL) {
647 id = xcalloc(1, sizeof(Identity));
648 id->key = k;
649 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
650 /* Increment the number of identities. */
651 tab->nentries++;
652 } else {
653 sshkey_free(k);
654 free(id->comment);
655 }
656 id->comment = comment;
657 id->death = death;
658 id->confirm = confirm;
659 send:
660 send_status(e, success);
661 }
662
663 /* XXX todo: encrypt sensitive data with passphrase */
664 static void
process_lock_agent(SocketEntry * e,int lock)665 process_lock_agent(SocketEntry *e, int lock)
666 {
667 int r, success = 0, delay;
668 char *passwd, passwdhash[LOCK_SIZE];
669 static u_int fail_count = 0;
670 size_t pwlen;
671
672 if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0)
673 fatal("%s: buffer error: %s", __func__, ssh_err(r));
674 if (pwlen == 0) {
675 debug("empty password not supported");
676 } else if (locked && !lock) {
677 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt),
678 passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0)
679 fatal("bcrypt_pbkdf");
680 if (timingsafe_bcmp(passwdhash, lock_passwd, LOCK_SIZE) == 0) {
681 debug("agent unlocked");
682 locked = 0;
683 fail_count = 0;
684 explicit_bzero(lock_passwd, sizeof(lock_passwd));
685 success = 1;
686 } else {
687 /* delay in 0.1s increments up to 10s */
688 if (fail_count < 100)
689 fail_count++;
690 delay = 100000 * fail_count;
691 debug("unlock failed, delaying %0.1lf seconds",
692 (double)delay/1000000);
693 usleep(delay);
694 }
695 explicit_bzero(passwdhash, sizeof(passwdhash));
696 } else if (!locked && lock) {
697 debug("agent locked");
698 locked = 1;
699 arc4random_buf(lock_salt, sizeof(lock_salt));
700 if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt),
701 lock_passwd, sizeof(lock_passwd), LOCK_ROUNDS) < 0)
702 fatal("bcrypt_pbkdf");
703 success = 1;
704 }
705 explicit_bzero(passwd, pwlen);
706 free(passwd);
707 send_status(e, success);
708 }
709
710 static void
no_identities(SocketEntry * e,u_int type)711 no_identities(SocketEntry *e, u_int type)
712 {
713 struct sshbuf *msg;
714 int r;
715
716 if ((msg = sshbuf_new()) == NULL)
717 fatal("%s: sshbuf_new failed", __func__);
718 if ((r = sshbuf_put_u8(msg,
719 (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
720 SSH_AGENT_RSA_IDENTITIES_ANSWER :
721 SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
722 (r = sshbuf_put_u32(msg, 0)) != 0 ||
723 (r = sshbuf_put_stringb(e->output, msg)) != 0)
724 fatal("%s: buffer error: %s", __func__, ssh_err(r));
725 sshbuf_free(msg);
726 }
727
728 #ifdef ENABLE_PKCS11
729 static void
process_add_smartcard_key(SocketEntry * e)730 process_add_smartcard_key(SocketEntry *e)
731 {
732 char *provider = NULL, *pin;
733 int r, i, version, count = 0, success = 0, confirm = 0;
734 u_int seconds;
735 time_t death = 0;
736 u_char type;
737 struct sshkey **keys = NULL, *k;
738 Identity *id;
739 Idtab *tab;
740
741 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
742 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0)
743 fatal("%s: buffer error: %s", __func__, ssh_err(r));
744
745 while (sshbuf_len(e->request)) {
746 if ((r = sshbuf_get_u8(e->request, &type)) != 0)
747 fatal("%s: buffer error: %s", __func__, ssh_err(r));
748 switch (type) {
749 case SSH_AGENT_CONSTRAIN_LIFETIME:
750 if ((r = sshbuf_get_u32(e->request, &seconds)) != 0)
751 fatal("%s: buffer error: %s",
752 __func__, ssh_err(r));
753 death = monotime() + seconds;
754 break;
755 case SSH_AGENT_CONSTRAIN_CONFIRM:
756 confirm = 1;
757 break;
758 default:
759 error("process_add_smartcard_key: "
760 "Unknown constraint type %d", type);
761 goto send;
762 }
763 }
764 if (lifetime && !death)
765 death = monotime() + lifetime;
766
767 count = pkcs11_add_provider(provider, pin, &keys);
768 for (i = 0; i < count; i++) {
769 k = keys[i];
770 version = k->type == KEY_RSA1 ? 1 : 2;
771 tab = idtab_lookup(version);
772 if (lookup_identity(k, version) == NULL) {
773 id = xcalloc(1, sizeof(Identity));
774 id->key = k;
775 id->provider = xstrdup(provider);
776 id->comment = xstrdup(provider); /* XXX */
777 id->death = death;
778 id->confirm = confirm;
779 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
780 tab->nentries++;
781 success = 1;
782 } else {
783 sshkey_free(k);
784 }
785 keys[i] = NULL;
786 }
787 send:
788 free(pin);
789 free(provider);
790 free(keys);
791 send_status(e, success);
792 }
793
794 static void
process_remove_smartcard_key(SocketEntry * e)795 process_remove_smartcard_key(SocketEntry *e)
796 {
797 char *provider = NULL, *pin = NULL;
798 int r, version, success = 0;
799 Identity *id, *nxt;
800 Idtab *tab;
801
802 if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
803 (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0)
804 fatal("%s: buffer error: %s", __func__, ssh_err(r));
805 free(pin);
806
807 for (version = 1; version < 3; version++) {
808 tab = idtab_lookup(version);
809 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
810 nxt = TAILQ_NEXT(id, next);
811 /* Skip file--based keys */
812 if (id->provider == NULL)
813 continue;
814 if (!strcmp(provider, id->provider)) {
815 TAILQ_REMOVE(&tab->idlist, id, next);
816 free_identity(id);
817 tab->nentries--;
818 }
819 }
820 }
821 if (pkcs11_del_provider(provider) == 0)
822 success = 1;
823 else
824 error("process_remove_smartcard_key:"
825 " pkcs11_del_provider failed");
826 free(provider);
827 send_status(e, success);
828 }
829 #endif /* ENABLE_PKCS11 */
830
831 /* dispatch incoming messages */
832
833 static void
process_message(SocketEntry * e)834 process_message(SocketEntry *e)
835 {
836 u_int msg_len;
837 u_char type;
838 const u_char *cp;
839 int r;
840
841 if (sshbuf_len(e->input) < 5)
842 return; /* Incomplete message. */
843 cp = sshbuf_ptr(e->input);
844 msg_len = PEEK_U32(cp);
845 if (msg_len > 256 * 1024) {
846 close_socket(e);
847 return;
848 }
849 if (sshbuf_len(e->input) < msg_len + 4)
850 return;
851
852 /* move the current input to e->request */
853 sshbuf_reset(e->request);
854 if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 ||
855 (r = sshbuf_get_u8(e->request, &type)) != 0)
856 fatal("%s: buffer error: %s", __func__, ssh_err(r));
857
858 /* check wheter agent is locked */
859 if (locked && type != SSH_AGENTC_UNLOCK) {
860 sshbuf_reset(e->request);
861 switch (type) {
862 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
863 case SSH2_AGENTC_REQUEST_IDENTITIES:
864 /* send empty lists */
865 no_identities(e, type);
866 break;
867 default:
868 /* send a fail message for all other request types */
869 send_status(e, 0);
870 }
871 return;
872 }
873
874 debug("type %d", type);
875 switch (type) {
876 case SSH_AGENTC_LOCK:
877 case SSH_AGENTC_UNLOCK:
878 process_lock_agent(e, type == SSH_AGENTC_LOCK);
879 break;
880 #ifdef WITH_SSH1
881 /* ssh1 */
882 case SSH_AGENTC_RSA_CHALLENGE:
883 process_authentication_challenge1(e);
884 break;
885 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
886 process_request_identities(e, 1);
887 break;
888 case SSH_AGENTC_ADD_RSA_IDENTITY:
889 case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
890 process_add_identity(e, 1);
891 break;
892 case SSH_AGENTC_REMOVE_RSA_IDENTITY:
893 process_remove_identity(e, 1);
894 break;
895 #endif
896 case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
897 process_remove_all_identities(e, 1); /* safe for !WITH_SSH1 */
898 break;
899 /* ssh2 */
900 case SSH2_AGENTC_SIGN_REQUEST:
901 process_sign_request2(e);
902 break;
903 case SSH2_AGENTC_REQUEST_IDENTITIES:
904 process_request_identities(e, 2);
905 break;
906 case SSH2_AGENTC_ADD_IDENTITY:
907 case SSH2_AGENTC_ADD_ID_CONSTRAINED:
908 process_add_identity(e, 2);
909 break;
910 case SSH2_AGENTC_REMOVE_IDENTITY:
911 process_remove_identity(e, 2);
912 break;
913 case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
914 process_remove_all_identities(e, 2);
915 break;
916 #ifdef ENABLE_PKCS11
917 case SSH_AGENTC_ADD_SMARTCARD_KEY:
918 case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
919 process_add_smartcard_key(e);
920 break;
921 case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
922 process_remove_smartcard_key(e);
923 break;
924 #endif /* ENABLE_PKCS11 */
925 default:
926 /* Unknown message. Respond with failure. */
927 error("Unknown message %d", type);
928 sshbuf_reset(e->request);
929 send_status(e, 0);
930 break;
931 }
932 }
933
934 static void
new_socket(sock_type type,int fd)935 new_socket(sock_type type, int fd)
936 {
937 u_int i, old_alloc, new_alloc;
938
939 set_nonblock(fd);
940
941 if (fd > max_fd)
942 max_fd = fd;
943
944 for (i = 0; i < sockets_alloc; i++)
945 if (sockets[i].type == AUTH_UNUSED) {
946 sockets[i].fd = fd;
947 if ((sockets[i].input = sshbuf_new()) == NULL)
948 fatal("%s: sshbuf_new failed", __func__);
949 if ((sockets[i].output = sshbuf_new()) == NULL)
950 fatal("%s: sshbuf_new failed", __func__);
951 if ((sockets[i].request = sshbuf_new()) == NULL)
952 fatal("%s: sshbuf_new failed", __func__);
953 sockets[i].type = type;
954 return;
955 }
956 old_alloc = sockets_alloc;
957 new_alloc = sockets_alloc + 10;
958 sockets = xreallocarray(sockets, new_alloc, sizeof(sockets[0]));
959 for (i = old_alloc; i < new_alloc; i++)
960 sockets[i].type = AUTH_UNUSED;
961 sockets_alloc = new_alloc;
962 sockets[old_alloc].fd = fd;
963 if ((sockets[old_alloc].input = sshbuf_new()) == NULL)
964 fatal("%s: sshbuf_new failed", __func__);
965 if ((sockets[old_alloc].output = sshbuf_new()) == NULL)
966 fatal("%s: sshbuf_new failed", __func__);
967 if ((sockets[old_alloc].request = sshbuf_new()) == NULL)
968 fatal("%s: sshbuf_new failed", __func__);
969 sockets[old_alloc].type = type;
970 }
971
972 static int
prepare_select(fd_set ** fdrp,fd_set ** fdwp,int * fdl,u_int * nallocp,struct timeval ** tvpp)973 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
974 struct timeval **tvpp)
975 {
976 u_int i, sz;
977 int n = 0;
978 static struct timeval tv;
979 time_t deadline;
980
981 for (i = 0; i < sockets_alloc; i++) {
982 switch (sockets[i].type) {
983 case AUTH_SOCKET:
984 case AUTH_CONNECTION:
985 n = MAX(n, sockets[i].fd);
986 break;
987 case AUTH_UNUSED:
988 break;
989 default:
990 fatal("Unknown socket type %d", sockets[i].type);
991 break;
992 }
993 }
994
995 sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
996 if (*fdrp == NULL || sz > *nallocp) {
997 free(*fdrp);
998 free(*fdwp);
999 *fdrp = xmalloc(sz);
1000 *fdwp = xmalloc(sz);
1001 *nallocp = sz;
1002 }
1003 if (n < *fdl)
1004 debug("XXX shrink: %d < %d", n, *fdl);
1005 *fdl = n;
1006 memset(*fdrp, 0, sz);
1007 memset(*fdwp, 0, sz);
1008
1009 for (i = 0; i < sockets_alloc; i++) {
1010 switch (sockets[i].type) {
1011 case AUTH_SOCKET:
1012 case AUTH_CONNECTION:
1013 FD_SET(sockets[i].fd, *fdrp);
1014 if (sshbuf_len(sockets[i].output) > 0)
1015 FD_SET(sockets[i].fd, *fdwp);
1016 break;
1017 default:
1018 break;
1019 }
1020 }
1021 deadline = reaper();
1022 if (parent_alive_interval != 0)
1023 deadline = (deadline == 0) ? parent_alive_interval :
1024 MIN(deadline, parent_alive_interval);
1025 if (deadline == 0) {
1026 *tvpp = NULL;
1027 } else {
1028 tv.tv_sec = deadline;
1029 tv.tv_usec = 0;
1030 *tvpp = &tv;
1031 }
1032 return (1);
1033 }
1034
1035 static void
after_select(fd_set * readset,fd_set * writeset)1036 after_select(fd_set *readset, fd_set *writeset)
1037 {
1038 struct sockaddr_un sunaddr;
1039 socklen_t slen;
1040 char buf[1024];
1041 int len, sock, r;
1042 u_int i, orig_alloc;
1043 uid_t euid;
1044 gid_t egid;
1045
1046 for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
1047 switch (sockets[i].type) {
1048 case AUTH_UNUSED:
1049 break;
1050 case AUTH_SOCKET:
1051 if (FD_ISSET(sockets[i].fd, readset)) {
1052 slen = sizeof(sunaddr);
1053 sock = accept(sockets[i].fd,
1054 (struct sockaddr *)&sunaddr, &slen);
1055 if (sock < 0) {
1056 error("accept from AUTH_SOCKET: %s",
1057 strerror(errno));
1058 break;
1059 }
1060 if (getpeereid(sock, &euid, &egid) < 0) {
1061 error("getpeereid %d failed: %s",
1062 sock, strerror(errno));
1063 close(sock);
1064 break;
1065 }
1066 if ((euid != 0) && (getuid() != euid)) {
1067 error("uid mismatch: "
1068 "peer euid %u != uid %u",
1069 (u_int) euid, (u_int) getuid());
1070 close(sock);
1071 break;
1072 }
1073 new_socket(AUTH_CONNECTION, sock);
1074 }
1075 break;
1076 case AUTH_CONNECTION:
1077 if (sshbuf_len(sockets[i].output) > 0 &&
1078 FD_ISSET(sockets[i].fd, writeset)) {
1079 len = write(sockets[i].fd,
1080 sshbuf_ptr(sockets[i].output),
1081 sshbuf_len(sockets[i].output));
1082 if (len == -1 && (errno == EAGAIN ||
1083 errno == EWOULDBLOCK ||
1084 errno == EINTR))
1085 continue;
1086 if (len <= 0) {
1087 close_socket(&sockets[i]);
1088 break;
1089 }
1090 if ((r = sshbuf_consume(sockets[i].output,
1091 len)) != 0)
1092 fatal("%s: buffer error: %s",
1093 __func__, ssh_err(r));
1094 }
1095 if (FD_ISSET(sockets[i].fd, readset)) {
1096 len = read(sockets[i].fd, buf, sizeof(buf));
1097 if (len == -1 && (errno == EAGAIN ||
1098 errno == EWOULDBLOCK ||
1099 errno == EINTR))
1100 continue;
1101 if (len <= 0) {
1102 close_socket(&sockets[i]);
1103 break;
1104 }
1105 if ((r = sshbuf_put(sockets[i].input,
1106 buf, len)) != 0)
1107 fatal("%s: buffer error: %s",
1108 __func__, ssh_err(r));
1109 explicit_bzero(buf, sizeof(buf));
1110 process_message(&sockets[i]);
1111 }
1112 break;
1113 default:
1114 fatal("Unknown type %d", sockets[i].type);
1115 }
1116 }
1117
1118 static void
cleanup_socket(void)1119 cleanup_socket(void)
1120 {
1121 if (cleanup_pid != 0 && getpid() != cleanup_pid)
1122 return;
1123 debug("%s: cleanup", __func__);
1124 if (socket_name[0])
1125 unlink(socket_name);
1126 if (socket_dir[0])
1127 rmdir(socket_dir);
1128 }
1129
1130 void
cleanup_exit(int i)1131 cleanup_exit(int i)
1132 {
1133 cleanup_socket();
1134 _exit(i);
1135 }
1136
1137 /*ARGSUSED*/
1138 static void
cleanup_handler(int sig)1139 cleanup_handler(int sig)
1140 {
1141 cleanup_socket();
1142 #ifdef ENABLE_PKCS11
1143 pkcs11_terminate();
1144 #endif
1145 _exit(2);
1146 }
1147
1148 static void
check_parent_exists(void)1149 check_parent_exists(void)
1150 {
1151 /*
1152 * If our parent has exited then getppid() will return (pid_t)1,
1153 * so testing for that should be safe.
1154 */
1155 if (parent_pid != -1 && getppid() != parent_pid) {
1156 /* printf("Parent has died - Authentication agent exiting.\n"); */
1157 cleanup_socket();
1158 _exit(2);
1159 }
1160 }
1161
1162 static void
usage(void)1163 usage(void)
1164 {
1165 fprintf(stderr,
1166 "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n"
1167 " [-t life] [command [arg ...]]\n"
1168 " ssh-agent [-c | -s] -k\n");
1169 exit(1);
1170 }
1171
1172 int
main(int ac,char ** av)1173 main(int ac, char **av)
1174 {
1175 int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0;
1176 int sock, fd, ch, result, saved_errno;
1177 u_int nalloc;
1178 char *shell, *format, *pidstr, *agentsocket = NULL;
1179 fd_set *readsetp = NULL, *writesetp = NULL;
1180 #ifdef HAVE_SETRLIMIT
1181 struct rlimit rlim;
1182 #endif
1183 extern int optind;
1184 extern char *optarg;
1185 pid_t pid;
1186 char pidstrbuf[1 + 3 * sizeof pid];
1187 struct timeval *tvp = NULL;
1188 size_t len;
1189 mode_t prev_mask;
1190
1191 /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1192 sanitise_stdfd();
1193
1194 /* drop */
1195 setegid(getgid());
1196 setgid(getgid());
1197
1198 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1199 /* Disable ptrace on Linux without sgid bit */
1200 prctl(PR_SET_DUMPABLE, 0);
1201 #endif
1202
1203 #ifdef WITH_OPENSSL
1204 OpenSSL_add_all_algorithms();
1205 #endif
1206
1207 __progname = ssh_get_progname(av[0]);
1208 seed_rng();
1209
1210 while ((ch = getopt(ac, av, "cDdksE:a:t:")) != -1) {
1211 switch (ch) {
1212 case 'E':
1213 fingerprint_hash = ssh_digest_alg_by_name(optarg);
1214 if (fingerprint_hash == -1)
1215 fatal("Invalid hash algorithm \"%s\"", optarg);
1216 break;
1217 case 'c':
1218 if (s_flag)
1219 usage();
1220 c_flag++;
1221 break;
1222 case 'k':
1223 k_flag++;
1224 break;
1225 case 's':
1226 if (c_flag)
1227 usage();
1228 s_flag++;
1229 break;
1230 case 'd':
1231 if (d_flag || D_flag)
1232 usage();
1233 d_flag++;
1234 break;
1235 case 'D':
1236 if (d_flag || D_flag)
1237 usage();
1238 D_flag++;
1239 break;
1240 case 'a':
1241 agentsocket = optarg;
1242 break;
1243 case 't':
1244 if ((lifetime = convtime(optarg)) == -1) {
1245 fprintf(stderr, "Invalid lifetime\n");
1246 usage();
1247 }
1248 break;
1249 default:
1250 usage();
1251 }
1252 }
1253 ac -= optind;
1254 av += optind;
1255
1256 if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag))
1257 usage();
1258
1259 if (ac == 0 && !c_flag && !s_flag) {
1260 shell = getenv("SHELL");
1261 if (shell != NULL && (len = strlen(shell)) > 2 &&
1262 strncmp(shell + len - 3, "csh", 3) == 0)
1263 c_flag = 1;
1264 }
1265 if (k_flag) {
1266 const char *errstr = NULL;
1267
1268 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1269 if (pidstr == NULL) {
1270 fprintf(stderr, "%s not set, cannot kill agent\n",
1271 SSH_AGENTPID_ENV_NAME);
1272 exit(1);
1273 }
1274 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1275 if (errstr) {
1276 fprintf(stderr,
1277 "%s=\"%s\", which is not a good PID: %s\n",
1278 SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1279 exit(1);
1280 }
1281 if (kill(pid, SIGTERM) == -1) {
1282 perror("kill");
1283 exit(1);
1284 }
1285 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1286 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1287 printf(format, SSH_AGENTPID_ENV_NAME);
1288 printf("echo Agent pid %ld killed;\n", (long)pid);
1289 exit(0);
1290 }
1291 parent_pid = getpid();
1292
1293 if (agentsocket == NULL) {
1294 /* Create private directory for agent socket */
1295 mktemp_proto(socket_dir, sizeof(socket_dir));
1296 if (mkdtemp(socket_dir) == NULL) {
1297 perror("mkdtemp: private socket dir");
1298 exit(1);
1299 }
1300 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1301 (long)parent_pid);
1302 } else {
1303 /* Try to use specified agent socket */
1304 socket_dir[0] = '\0';
1305 strlcpy(socket_name, agentsocket, sizeof socket_name);
1306 }
1307
1308 /*
1309 * Create socket early so it will exist before command gets run from
1310 * the parent.
1311 */
1312 prev_mask = umask(0177);
1313 sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0);
1314 if (sock < 0) {
1315 /* XXX - unix_listener() calls error() not perror() */
1316 *socket_name = '\0'; /* Don't unlink any existing file */
1317 cleanup_exit(1);
1318 }
1319 umask(prev_mask);
1320
1321 /*
1322 * Fork, and have the parent execute the command, if any, or present
1323 * the socket data. The child continues as the authentication agent.
1324 */
1325 if (D_flag || d_flag) {
1326 log_init(__progname,
1327 d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO,
1328 SYSLOG_FACILITY_AUTH, 1);
1329 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1330 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1331 SSH_AUTHSOCKET_ENV_NAME);
1332 printf("echo Agent pid %ld;\n", (long)parent_pid);
1333 goto skip;
1334 }
1335 pid = fork();
1336 if (pid == -1) {
1337 perror("fork");
1338 cleanup_exit(1);
1339 }
1340 if (pid != 0) { /* Parent - execute the given command. */
1341 close(sock);
1342 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1343 if (ac == 0) {
1344 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1345 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1346 SSH_AUTHSOCKET_ENV_NAME);
1347 printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1348 SSH_AGENTPID_ENV_NAME);
1349 printf("echo Agent pid %ld;\n", (long)pid);
1350 exit(0);
1351 }
1352 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1353 setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1354 perror("setenv");
1355 exit(1);
1356 }
1357 execvp(av[0], av);
1358 perror(av[0]);
1359 exit(1);
1360 }
1361 /* child */
1362 log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1363
1364 if (setsid() == -1) {
1365 error("setsid: %s", strerror(errno));
1366 cleanup_exit(1);
1367 }
1368
1369 (void)chdir("/");
1370 if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1371 /* XXX might close listen socket */
1372 (void)dup2(fd, STDIN_FILENO);
1373 (void)dup2(fd, STDOUT_FILENO);
1374 (void)dup2(fd, STDERR_FILENO);
1375 if (fd > 2)
1376 close(fd);
1377 }
1378
1379 #ifdef HAVE_SETRLIMIT
1380 /* deny core dumps, since memory contains unencrypted private keys */
1381 rlim.rlim_cur = rlim.rlim_max = 0;
1382 if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1383 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1384 cleanup_exit(1);
1385 }
1386 #endif
1387
1388 skip:
1389
1390 cleanup_pid = getpid();
1391
1392 #ifdef ENABLE_PKCS11
1393 pkcs11_init(0);
1394 #endif
1395 new_socket(AUTH_SOCKET, sock);
1396 if (ac > 0)
1397 parent_alive_interval = 10;
1398 idtab_init();
1399 signal(SIGPIPE, SIG_IGN);
1400 signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN);
1401 signal(SIGHUP, cleanup_handler);
1402 signal(SIGTERM, cleanup_handler);
1403 nalloc = 0;
1404
1405 while (1) {
1406 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1407 result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1408 saved_errno = errno;
1409 if (parent_alive_interval != 0)
1410 check_parent_exists();
1411 (void) reaper(); /* remove expired keys */
1412 if (result < 0) {
1413 if (saved_errno == EINTR)
1414 continue;
1415 fatal("select: %s", strerror(saved_errno));
1416 } else if (result > 0)
1417 after_select(readsetp, writesetp);
1418 }
1419 /* NOTREACHED */
1420 }
1421