xref: /freebsd/crypto/openssh/ssh-agent.c (revision 63d1fd5970ec814904aa0f4580b10a0d302d08b2)
1 /* $OpenBSD: ssh-agent.c,v 1.212 2016/02/15 09:47:49 dtucker 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 __RCSID("$FreeBSD$");
39 
40 #include <sys/param.h>	/* MIN MAX */
41 #include <sys/types.h>
42 #include <sys/param.h>
43 #include <sys/resource.h>
44 #include <sys/stat.h>
45 #include <sys/socket.h>
46 #ifdef HAVE_SYS_TIME_H
47 # include <sys/time.h>
48 #endif
49 #ifdef HAVE_SYS_UN_H
50 # include <sys/un.h>
51 #endif
52 #include "openbsd-compat/sys-queue.h"
53 
54 #ifdef WITH_OPENSSL
55 #include <openssl/evp.h>
56 #include "openbsd-compat/openssl-compat.h"
57 #endif
58 
59 #include <errno.h>
60 #include <fcntl.h>
61 #include <limits.h>
62 #ifdef HAVE_PATHS_H
63 # include <paths.h>
64 #endif
65 #include <signal.h>
66 #include <stdarg.h>
67 #include <stdio.h>
68 #include <stdlib.h>
69 #include <time.h>
70 #include <string.h>
71 #include <unistd.h>
72 #ifdef HAVE_UTIL_H
73 # include <util.h>
74 #endif
75 
76 #include "xmalloc.h"
77 #include "ssh.h"
78 #include "rsa.h"
79 #include "sshbuf.h"
80 #include "sshkey.h"
81 #include "authfd.h"
82 #include "compat.h"
83 #include "log.h"
84 #include "misc.h"
85 #include "digest.h"
86 #include "ssherr.h"
87 #include "match.h"
88 
89 #ifdef ENABLE_PKCS11
90 #include "ssh-pkcs11.h"
91 #endif
92 
93 #ifndef DEFAULT_PKCS11_WHITELIST
94 # define DEFAULT_PKCS11_WHITELIST "/usr/lib/*,/usr/local/lib/*"
95 #endif
96 
97 #if defined(HAVE_SYS_PRCTL_H)
98 #include <sys/prctl.h>	/* For prctl() and PR_SET_DUMPABLE */
99 #endif
100 
101 typedef enum {
102 	AUTH_UNUSED,
103 	AUTH_SOCKET,
104 	AUTH_CONNECTION
105 } sock_type;
106 
107 typedef struct {
108 	int fd;
109 	sock_type type;
110 	struct sshbuf *input;
111 	struct sshbuf *output;
112 	struct sshbuf *request;
113 } SocketEntry;
114 
115 u_int sockets_alloc = 0;
116 SocketEntry *sockets = NULL;
117 
118 typedef struct identity {
119 	TAILQ_ENTRY(identity) next;
120 	struct sshkey *key;
121 	char *comment;
122 	char *provider;
123 	time_t death;
124 	u_int confirm;
125 } Identity;
126 
127 typedef struct {
128 	int nentries;
129 	TAILQ_HEAD(idqueue, identity) idlist;
130 } Idtab;
131 
132 /* private key table, one per protocol version */
133 Idtab idtable[3];
134 
135 int max_fd = 0;
136 
137 /* pid of shell == parent of agent */
138 pid_t parent_pid = -1;
139 time_t parent_alive_interval = 0;
140 
141 /* pid of process for which cleanup_socket is applicable */
142 pid_t cleanup_pid = 0;
143 
144 /* pathname and directory for AUTH_SOCKET */
145 char socket_name[PATH_MAX];
146 char socket_dir[PATH_MAX];
147 
148 /* PKCS#11 path whitelist */
149 static char *pkcs11_whitelist;
150 
151 /* locking */
152 #define LOCK_SIZE	32
153 #define LOCK_SALT_SIZE	16
154 #define LOCK_ROUNDS	1
155 int locked = 0;
156 char lock_passwd[LOCK_SIZE];
157 char lock_salt[LOCK_SALT_SIZE];
158 
159 extern char *__progname;
160 
161 /* Default lifetime in seconds (0 == forever) */
162 static long lifetime = 0;
163 
164 static int fingerprint_hash = SSH_FP_HASH_DEFAULT;
165 
166 /*
167  * Client connection count; incremented in new_socket() and decremented in
168  * close_socket().  When it reaches 0, ssh-agent will exit.  Since it is
169  * normally initialized to 1, it will never reach 0.  However, if the -x
170  * option is specified, it is initialized to 0 in main(); in that case,
171  * ssh-agent will exit as soon as it has had at least one client but no
172  * longer has any.
173  */
174 static int xcount = 1;
175 
176 static void
177 close_socket(SocketEntry *e)
178 {
179 	int last = 0;
180 
181 	if (e->type == AUTH_CONNECTION) {
182 		debug("xcount %d -> %d", xcount, xcount - 1);
183 		if (--xcount == 0)
184 			last = 1;
185 	}
186 	close(e->fd);
187 	e->fd = -1;
188 	e->type = AUTH_UNUSED;
189 	sshbuf_free(e->input);
190 	sshbuf_free(e->output);
191 	sshbuf_free(e->request);
192 	if (last)
193 		cleanup_exit(0);
194 }
195 
196 static void
197 idtab_init(void)
198 {
199 	int i;
200 
201 	for (i = 0; i <=2; i++) {
202 		TAILQ_INIT(&idtable[i].idlist);
203 		idtable[i].nentries = 0;
204 	}
205 }
206 
207 /* return private key table for requested protocol version */
208 static Idtab *
209 idtab_lookup(int version)
210 {
211 	if (version < 1 || version > 2)
212 		fatal("internal error, bad protocol version %d", version);
213 	return &idtable[version];
214 }
215 
216 static void
217 free_identity(Identity *id)
218 {
219 	sshkey_free(id->key);
220 	free(id->provider);
221 	free(id->comment);
222 	free(id);
223 }
224 
225 /* return matching private key for given public key */
226 static Identity *
227 lookup_identity(struct sshkey *key, int version)
228 {
229 	Identity *id;
230 
231 	Idtab *tab = idtab_lookup(version);
232 	TAILQ_FOREACH(id, &tab->idlist, next) {
233 		if (sshkey_equal(key, id->key))
234 			return (id);
235 	}
236 	return (NULL);
237 }
238 
239 /* Check confirmation of keysign request */
240 static int
241 confirm_key(Identity *id)
242 {
243 	char *p;
244 	int ret = -1;
245 
246 	p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT);
247 	if (p != NULL &&
248 	    ask_permission("Allow use of key %s?\nKey fingerprint %s.",
249 	    id->comment, p))
250 		ret = 0;
251 	free(p);
252 
253 	return (ret);
254 }
255 
256 static void
257 send_status(SocketEntry *e, int success)
258 {
259 	int r;
260 
261 	if ((r = sshbuf_put_u32(e->output, 1)) != 0 ||
262 	    (r = sshbuf_put_u8(e->output, success ?
263 	    SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0)
264 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
265 }
266 
267 /* send list of supported public keys to 'client' */
268 static void
269 process_request_identities(SocketEntry *e, int version)
270 {
271 	Idtab *tab = idtab_lookup(version);
272 	Identity *id;
273 	struct sshbuf *msg;
274 	int r;
275 
276 	if ((msg = sshbuf_new()) == NULL)
277 		fatal("%s: sshbuf_new failed", __func__);
278 	if ((r = sshbuf_put_u8(msg, (version == 1) ?
279 	    SSH_AGENT_RSA_IDENTITIES_ANSWER :
280 	    SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
281 	    (r = sshbuf_put_u32(msg, tab->nentries)) != 0)
282 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
283 	TAILQ_FOREACH(id, &tab->idlist, next) {
284 		if (id->key->type == KEY_RSA1) {
285 #ifdef WITH_SSH1
286 			if ((r = sshbuf_put_u32(msg,
287 			    BN_num_bits(id->key->rsa->n))) != 0 ||
288 			    (r = sshbuf_put_bignum1(msg,
289 			    id->key->rsa->e)) != 0 ||
290 			    (r = sshbuf_put_bignum1(msg,
291 			    id->key->rsa->n)) != 0)
292 				fatal("%s: buffer error: %s",
293 				    __func__, ssh_err(r));
294 #endif
295 		} else {
296 			u_char *blob;
297 			size_t blen;
298 
299 			if ((r = sshkey_to_blob(id->key, &blob, &blen)) != 0) {
300 				error("%s: sshkey_to_blob: %s", __func__,
301 				    ssh_err(r));
302 				continue;
303 			}
304 			if ((r = sshbuf_put_string(msg, blob, blen)) != 0)
305 				fatal("%s: buffer error: %s",
306 				    __func__, ssh_err(r));
307 			free(blob);
308 		}
309 		if ((r = sshbuf_put_cstring(msg, id->comment)) != 0)
310 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
311 	}
312 	if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
313 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
314 	sshbuf_free(msg);
315 }
316 
317 #ifdef WITH_SSH1
318 /* ssh1 only */
319 static void
320 process_authentication_challenge1(SocketEntry *e)
321 {
322 	u_char buf[32], mdbuf[16], session_id[16];
323 	u_int response_type;
324 	BIGNUM *challenge;
325 	Identity *id;
326 	int r, len;
327 	struct sshbuf *msg;
328 	struct ssh_digest_ctx *md;
329 	struct sshkey *key;
330 
331 	if ((msg = sshbuf_new()) == NULL)
332 		fatal("%s: sshbuf_new failed", __func__);
333 	if ((key = sshkey_new(KEY_RSA1)) == NULL)
334 		fatal("%s: sshkey_new failed", __func__);
335 	if ((challenge = BN_new()) == NULL)
336 		fatal("%s: BN_new failed", __func__);
337 
338 	if ((r = sshbuf_get_u32(e->request, NULL)) != 0 || /* ignored */
339 	    (r = sshbuf_get_bignum1(e->request, key->rsa->e)) != 0 ||
340 	    (r = sshbuf_get_bignum1(e->request, key->rsa->n)) != 0 ||
341 	    (r = sshbuf_get_bignum1(e->request, challenge)))
342 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
343 
344 	/* Only protocol 1.1 is supported */
345 	if (sshbuf_len(e->request) == 0)
346 		goto failure;
347 	if ((r = sshbuf_get(e->request, session_id, sizeof(session_id))) != 0 ||
348 	    (r = sshbuf_get_u32(e->request, &response_type)) != 0)
349 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
350 	if (response_type != 1)
351 		goto failure;
352 
353 	id = lookup_identity(key, 1);
354 	if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
355 		struct sshkey *private = id->key;
356 		/* Decrypt the challenge using the private key. */
357 		if ((r = rsa_private_decrypt(challenge, challenge,
358 		    private->rsa) != 0)) {
359 			fatal("%s: rsa_public_encrypt: %s", __func__,
360 			    ssh_err(r));
361 			goto failure;	/* XXX ? */
362 		}
363 
364 		/* The response is MD5 of decrypted challenge plus session id */
365 		len = BN_num_bytes(challenge);
366 		if (len <= 0 || len > 32) {
367 			logit("%s: bad challenge length %d", __func__, len);
368 			goto failure;
369 		}
370 		memset(buf, 0, 32);
371 		BN_bn2bin(challenge, buf + 32 - len);
372 		if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
373 		    ssh_digest_update(md, buf, 32) < 0 ||
374 		    ssh_digest_update(md, session_id, 16) < 0 ||
375 		    ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0)
376 			fatal("%s: md5 failed", __func__);
377 		ssh_digest_free(md);
378 
379 		/* Send the response. */
380 		if ((r = sshbuf_put_u8(msg, SSH_AGENT_RSA_RESPONSE)) != 0 ||
381 		    (r = sshbuf_put(msg, mdbuf, sizeof(mdbuf))) != 0)
382 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
383 		goto send;
384 	}
385 
386  failure:
387 	/* Unknown identity or protocol error.  Send failure. */
388 	if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
389 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
390  send:
391 	if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
392 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
393 	sshkey_free(key);
394 	BN_clear_free(challenge);
395 	sshbuf_free(msg);
396 }
397 #endif
398 
399 static char *
400 agent_decode_alg(struct sshkey *key, u_int flags)
401 {
402 	if (key->type == KEY_RSA) {
403 		if (flags & SSH_AGENT_RSA_SHA2_256)
404 			return "rsa-sha2-256";
405 		else if (flags & SSH_AGENT_RSA_SHA2_512)
406 			return "rsa-sha2-512";
407 	}
408 	return NULL;
409 }
410 
411 /* ssh2 only */
412 static void
413 process_sign_request2(SocketEntry *e)
414 {
415 	u_char *blob, *data, *signature = NULL;
416 	size_t blen, dlen, slen = 0;
417 	u_int compat = 0, flags;
418 	int r, ok = -1;
419 	struct sshbuf *msg;
420 	struct sshkey *key;
421 	struct identity *id;
422 
423 	if ((msg = sshbuf_new()) == NULL)
424 		fatal("%s: sshbuf_new failed", __func__);
425 	if ((r = sshbuf_get_string(e->request, &blob, &blen)) != 0 ||
426 	    (r = sshbuf_get_string(e->request, &data, &dlen)) != 0 ||
427 	    (r = sshbuf_get_u32(e->request, &flags)) != 0)
428 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
429 	if (flags & SSH_AGENT_OLD_SIGNATURE)
430 		compat = SSH_BUG_SIGBLOB;
431 	if ((r = sshkey_from_blob(blob, blen, &key)) != 0) {
432 		error("%s: cannot parse key blob: %s", __func__, ssh_err(r));
433 		goto send;
434 	}
435 	if ((id = lookup_identity(key, 2)) == NULL) {
436 		verbose("%s: %s key not found", __func__, sshkey_type(key));
437 		goto send;
438 	}
439 	if (id->confirm && confirm_key(id) != 0) {
440 		verbose("%s: user refused key", __func__);
441 		goto send;
442 	}
443 	if ((r = sshkey_sign(id->key, &signature, &slen,
444 	    data, dlen, agent_decode_alg(key, flags), compat)) != 0) {
445 		error("%s: sshkey_sign: %s", __func__, ssh_err(r));
446 		goto send;
447 	}
448 	/* Success */
449 	ok = 0;
450  send:
451 	sshkey_free(key);
452 	if (ok == 0) {
453 		if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 ||
454 		    (r = sshbuf_put_string(msg, signature, slen)) != 0)
455 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
456 	} else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
457 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
458 
459 	if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
460 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
461 
462 	sshbuf_free(msg);
463 	free(data);
464 	free(blob);
465 	free(signature);
466 }
467 
468 /* shared */
469 static void
470 process_remove_identity(SocketEntry *e, int version)
471 {
472 	size_t blen;
473 	int r, success = 0;
474 	struct sshkey *key = NULL;
475 	u_char *blob;
476 #ifdef WITH_SSH1
477 	u_int bits;
478 #endif /* WITH_SSH1 */
479 
480 	switch (version) {
481 #ifdef WITH_SSH1
482 	case 1:
483 		if ((key = sshkey_new(KEY_RSA1)) == NULL) {
484 			error("%s: sshkey_new failed", __func__);
485 			return;
486 		}
487 		if ((r = sshbuf_get_u32(e->request, &bits)) != 0 ||
488 		    (r = sshbuf_get_bignum1(e->request, key->rsa->e)) != 0 ||
489 		    (r = sshbuf_get_bignum1(e->request, key->rsa->n)) != 0)
490 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
491 
492 		if (bits != sshkey_size(key))
493 			logit("Warning: identity keysize mismatch: "
494 			    "actual %u, announced %u",
495 			    sshkey_size(key), bits);
496 		break;
497 #endif /* WITH_SSH1 */
498 	case 2:
499 		if ((r = sshbuf_get_string(e->request, &blob, &blen)) != 0)
500 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
501 		if ((r = sshkey_from_blob(blob, blen, &key)) != 0)
502 			error("%s: sshkey_from_blob failed: %s",
503 			    __func__, ssh_err(r));
504 		free(blob);
505 		break;
506 	}
507 	if (key != NULL) {
508 		Identity *id = lookup_identity(key, version);
509 		if (id != NULL) {
510 			/*
511 			 * We have this key.  Free the old key.  Since we
512 			 * don't want to leave empty slots in the middle of
513 			 * the array, we actually free the key there and move
514 			 * all the entries between the empty slot and the end
515 			 * of the array.
516 			 */
517 			Idtab *tab = idtab_lookup(version);
518 			if (tab->nentries < 1)
519 				fatal("process_remove_identity: "
520 				    "internal error: tab->nentries %d",
521 				    tab->nentries);
522 			TAILQ_REMOVE(&tab->idlist, id, next);
523 			free_identity(id);
524 			tab->nentries--;
525 			success = 1;
526 		}
527 		sshkey_free(key);
528 	}
529 	send_status(e, success);
530 }
531 
532 static void
533 process_remove_all_identities(SocketEntry *e, int version)
534 {
535 	Idtab *tab = idtab_lookup(version);
536 	Identity *id;
537 
538 	/* Loop over all identities and clear the keys. */
539 	for (id = TAILQ_FIRST(&tab->idlist); id;
540 	    id = TAILQ_FIRST(&tab->idlist)) {
541 		TAILQ_REMOVE(&tab->idlist, id, next);
542 		free_identity(id);
543 	}
544 
545 	/* Mark that there are no identities. */
546 	tab->nentries = 0;
547 
548 	/* Send success. */
549 	send_status(e, 1);
550 }
551 
552 /* removes expired keys and returns number of seconds until the next expiry */
553 static time_t
554 reaper(void)
555 {
556 	time_t deadline = 0, now = monotime();
557 	Identity *id, *nxt;
558 	int version;
559 	Idtab *tab;
560 
561 	for (version = 1; version < 3; version++) {
562 		tab = idtab_lookup(version);
563 		for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
564 			nxt = TAILQ_NEXT(id, next);
565 			if (id->death == 0)
566 				continue;
567 			if (now >= id->death) {
568 				debug("expiring key '%s'", id->comment);
569 				TAILQ_REMOVE(&tab->idlist, id, next);
570 				free_identity(id);
571 				tab->nentries--;
572 			} else
573 				deadline = (deadline == 0) ? id->death :
574 				    MIN(deadline, id->death);
575 		}
576 	}
577 	if (deadline == 0 || deadline <= now)
578 		return 0;
579 	else
580 		return (deadline - now);
581 }
582 
583 /*
584  * XXX this and the corresponding serialisation function probably belongs
585  * in key.c
586  */
587 #ifdef WITH_SSH1
588 static int
589 agent_decode_rsa1(struct sshbuf *m, struct sshkey **kp)
590 {
591 	struct sshkey *k = NULL;
592 	int r = SSH_ERR_INTERNAL_ERROR;
593 
594 	*kp = NULL;
595 	if ((k = sshkey_new_private(KEY_RSA1)) == NULL)
596 		return SSH_ERR_ALLOC_FAIL;
597 
598 	if ((r = sshbuf_get_u32(m, NULL)) != 0 ||		/* ignored */
599 	    (r = sshbuf_get_bignum1(m, k->rsa->n)) != 0 ||
600 	    (r = sshbuf_get_bignum1(m, k->rsa->e)) != 0 ||
601 	    (r = sshbuf_get_bignum1(m, k->rsa->d)) != 0 ||
602 	    (r = sshbuf_get_bignum1(m, k->rsa->iqmp)) != 0 ||
603 	    /* SSH1 and SSL have p and q swapped */
604 	    (r = sshbuf_get_bignum1(m, k->rsa->q)) != 0 ||	/* p */
605 	    (r = sshbuf_get_bignum1(m, k->rsa->p)) != 0) 	/* q */
606 		goto out;
607 
608 	/* Generate additional parameters */
609 	if ((r = rsa_generate_additional_parameters(k->rsa)) != 0)
610 		goto out;
611 	/* enable blinding */
612 	if (RSA_blinding_on(k->rsa, NULL) != 1) {
613 		r = SSH_ERR_LIBCRYPTO_ERROR;
614 		goto out;
615 	}
616 
617 	r = 0; /* success */
618  out:
619 	if (r == 0)
620 		*kp = k;
621 	else
622 		sshkey_free(k);
623 	return r;
624 }
625 #endif /* WITH_SSH1 */
626 
627 static void
628 process_add_identity(SocketEntry *e, int version)
629 {
630 	Idtab *tab = idtab_lookup(version);
631 	Identity *id;
632 	int success = 0, confirm = 0;
633 	u_int seconds;
634 	char *comment = NULL;
635 	time_t death = 0;
636 	struct sshkey *k = NULL;
637 	u_char ctype;
638 	int r = SSH_ERR_INTERNAL_ERROR;
639 
640 	switch (version) {
641 #ifdef WITH_SSH1
642 	case 1:
643 		r = agent_decode_rsa1(e->request, &k);
644 		break;
645 #endif /* WITH_SSH1 */
646 	case 2:
647 		r = sshkey_private_deserialize(e->request, &k);
648 		break;
649 	}
650 	if (r != 0 || k == NULL ||
651 	    (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) {
652 		error("%s: decode private key: %s", __func__, ssh_err(r));
653 		goto err;
654 	}
655 
656 	while (sshbuf_len(e->request)) {
657 		if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) {
658 			error("%s: buffer error: %s", __func__, ssh_err(r));
659 			goto err;
660 		}
661 		switch (ctype) {
662 		case SSH_AGENT_CONSTRAIN_LIFETIME:
663 			if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) {
664 				error("%s: bad lifetime constraint: %s",
665 				    __func__, ssh_err(r));
666 				goto err;
667 			}
668 			death = monotime() + seconds;
669 			break;
670 		case SSH_AGENT_CONSTRAIN_CONFIRM:
671 			confirm = 1;
672 			break;
673 		default:
674 			error("%s: Unknown constraint %d", __func__, ctype);
675  err:
676 			sshbuf_reset(e->request);
677 			free(comment);
678 			sshkey_free(k);
679 			goto send;
680 		}
681 	}
682 
683 	success = 1;
684 	if (lifetime && !death)
685 		death = monotime() + lifetime;
686 	if ((id = lookup_identity(k, version)) == NULL) {
687 		id = xcalloc(1, sizeof(Identity));
688 		id->key = k;
689 		TAILQ_INSERT_TAIL(&tab->idlist, id, next);
690 		/* Increment the number of identities. */
691 		tab->nentries++;
692 	} else {
693 		sshkey_free(k);
694 		free(id->comment);
695 	}
696 	id->comment = comment;
697 	id->death = death;
698 	id->confirm = confirm;
699 send:
700 	send_status(e, success);
701 }
702 
703 /* XXX todo: encrypt sensitive data with passphrase */
704 static void
705 process_lock_agent(SocketEntry *e, int lock)
706 {
707 	int r, success = 0, delay;
708 	char *passwd, passwdhash[LOCK_SIZE];
709 	static u_int fail_count = 0;
710 	size_t pwlen;
711 
712 	if ((r = sshbuf_get_cstring(e->request, &passwd, &pwlen)) != 0)
713 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
714 	if (pwlen == 0) {
715 		debug("empty password not supported");
716 	} else if (locked && !lock) {
717 		if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt),
718 		    passwdhash, sizeof(passwdhash), LOCK_ROUNDS) < 0)
719 			fatal("bcrypt_pbkdf");
720 		if (timingsafe_bcmp(passwdhash, lock_passwd, LOCK_SIZE) == 0) {
721 			debug("agent unlocked");
722 			locked = 0;
723 			fail_count = 0;
724 			explicit_bzero(lock_passwd, sizeof(lock_passwd));
725 			success = 1;
726 		} else {
727 			/* delay in 0.1s increments up to 10s */
728 			if (fail_count < 100)
729 				fail_count++;
730 			delay = 100000 * fail_count;
731 			debug("unlock failed, delaying %0.1lf seconds",
732 			    (double)delay/1000000);
733 			usleep(delay);
734 		}
735 		explicit_bzero(passwdhash, sizeof(passwdhash));
736 	} else if (!locked && lock) {
737 		debug("agent locked");
738 		locked = 1;
739 		arc4random_buf(lock_salt, sizeof(lock_salt));
740 		if (bcrypt_pbkdf(passwd, pwlen, lock_salt, sizeof(lock_salt),
741 		    lock_passwd, sizeof(lock_passwd), LOCK_ROUNDS) < 0)
742 			fatal("bcrypt_pbkdf");
743 		success = 1;
744 	}
745 	explicit_bzero(passwd, pwlen);
746 	free(passwd);
747 	send_status(e, success);
748 }
749 
750 static void
751 no_identities(SocketEntry *e, u_int type)
752 {
753 	struct sshbuf *msg;
754 	int r;
755 
756 	if ((msg = sshbuf_new()) == NULL)
757 		fatal("%s: sshbuf_new failed", __func__);
758 	if ((r = sshbuf_put_u8(msg,
759 	    (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
760 	    SSH_AGENT_RSA_IDENTITIES_ANSWER :
761 	    SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
762 	    (r = sshbuf_put_u32(msg, 0)) != 0 ||
763 	    (r = sshbuf_put_stringb(e->output, msg)) != 0)
764 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
765 	sshbuf_free(msg);
766 }
767 
768 #ifdef ENABLE_PKCS11
769 static void
770 process_add_smartcard_key(SocketEntry *e)
771 {
772 	char *provider = NULL, *pin, canonical_provider[PATH_MAX];
773 	int r, i, version, count = 0, success = 0, confirm = 0;
774 	u_int seconds;
775 	time_t death = 0;
776 	u_char type;
777 	struct sshkey **keys = NULL, *k;
778 	Identity *id;
779 	Idtab *tab;
780 
781 	if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
782 	    (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0)
783 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
784 
785 	while (sshbuf_len(e->request)) {
786 		if ((r = sshbuf_get_u8(e->request, &type)) != 0)
787 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
788 		switch (type) {
789 		case SSH_AGENT_CONSTRAIN_LIFETIME:
790 			if ((r = sshbuf_get_u32(e->request, &seconds)) != 0)
791 				fatal("%s: buffer error: %s",
792 				    __func__, ssh_err(r));
793 			death = monotime() + seconds;
794 			break;
795 		case SSH_AGENT_CONSTRAIN_CONFIRM:
796 			confirm = 1;
797 			break;
798 		default:
799 			error("process_add_smartcard_key: "
800 			    "Unknown constraint type %d", type);
801 			goto send;
802 		}
803 	}
804 	if (realpath(provider, canonical_provider) == NULL) {
805 		verbose("failed PKCS#11 add of \"%.100s\": realpath: %s",
806 		    provider, strerror(errno));
807 		goto send;
808 	}
809 	if (match_pattern_list(canonical_provider, pkcs11_whitelist, 0) != 1) {
810 		verbose("refusing PKCS#11 add of \"%.100s\": "
811 		    "provider not whitelisted", canonical_provider);
812 		goto send;
813 	}
814 	debug("%s: add %.100s", __func__, canonical_provider);
815 	if (lifetime && !death)
816 		death = monotime() + lifetime;
817 
818 	count = pkcs11_add_provider(canonical_provider, pin, &keys);
819 	for (i = 0; i < count; i++) {
820 		k = keys[i];
821 		version = k->type == KEY_RSA1 ? 1 : 2;
822 		tab = idtab_lookup(version);
823 		if (lookup_identity(k, version) == NULL) {
824 			id = xcalloc(1, sizeof(Identity));
825 			id->key = k;
826 			id->provider = xstrdup(canonical_provider);
827 			id->comment = xstrdup(canonical_provider); /* XXX */
828 			id->death = death;
829 			id->confirm = confirm;
830 			TAILQ_INSERT_TAIL(&tab->idlist, id, next);
831 			tab->nentries++;
832 			success = 1;
833 		} else {
834 			sshkey_free(k);
835 		}
836 		keys[i] = NULL;
837 	}
838 send:
839 	free(pin);
840 	free(provider);
841 	free(keys);
842 	send_status(e, success);
843 }
844 
845 static void
846 process_remove_smartcard_key(SocketEntry *e)
847 {
848 	char *provider = NULL, *pin = NULL;
849 	int r, version, success = 0;
850 	Identity *id, *nxt;
851 	Idtab *tab;
852 
853 	if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
854 	    (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0)
855 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
856 	free(pin);
857 
858 	for (version = 1; version < 3; version++) {
859 		tab = idtab_lookup(version);
860 		for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
861 			nxt = TAILQ_NEXT(id, next);
862 			/* Skip file--based keys */
863 			if (id->provider == NULL)
864 				continue;
865 			if (!strcmp(provider, id->provider)) {
866 				TAILQ_REMOVE(&tab->idlist, id, next);
867 				free_identity(id);
868 				tab->nentries--;
869 			}
870 		}
871 	}
872 	if (pkcs11_del_provider(provider) == 0)
873 		success = 1;
874 	else
875 		error("process_remove_smartcard_key:"
876 		    " pkcs11_del_provider failed");
877 	free(provider);
878 	send_status(e, success);
879 }
880 #endif /* ENABLE_PKCS11 */
881 
882 /* dispatch incoming messages */
883 
884 static void
885 process_message(SocketEntry *e)
886 {
887 	u_int msg_len;
888 	u_char type;
889 	const u_char *cp;
890 	int r;
891 
892 	if (sshbuf_len(e->input) < 5)
893 		return;		/* Incomplete message. */
894 	cp = sshbuf_ptr(e->input);
895 	msg_len = PEEK_U32(cp);
896 	if (msg_len > 256 * 1024) {
897 		close_socket(e);
898 		return;
899 	}
900 	if (sshbuf_len(e->input) < msg_len + 4)
901 		return;
902 
903 	/* move the current input to e->request */
904 	sshbuf_reset(e->request);
905 	if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 ||
906 	    (r = sshbuf_get_u8(e->request, &type)) != 0)
907 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
908 
909 	/* check wheter agent is locked */
910 	if (locked && type != SSH_AGENTC_UNLOCK) {
911 		sshbuf_reset(e->request);
912 		switch (type) {
913 		case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
914 		case SSH2_AGENTC_REQUEST_IDENTITIES:
915 			/* send empty lists */
916 			no_identities(e, type);
917 			break;
918 		default:
919 			/* send a fail message for all other request types */
920 			send_status(e, 0);
921 		}
922 		return;
923 	}
924 
925 	debug("type %d", type);
926 	switch (type) {
927 	case SSH_AGENTC_LOCK:
928 	case SSH_AGENTC_UNLOCK:
929 		process_lock_agent(e, type == SSH_AGENTC_LOCK);
930 		break;
931 #ifdef WITH_SSH1
932 	/* ssh1 */
933 	case SSH_AGENTC_RSA_CHALLENGE:
934 		process_authentication_challenge1(e);
935 		break;
936 	case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
937 		process_request_identities(e, 1);
938 		break;
939 	case SSH_AGENTC_ADD_RSA_IDENTITY:
940 	case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
941 		process_add_identity(e, 1);
942 		break;
943 	case SSH_AGENTC_REMOVE_RSA_IDENTITY:
944 		process_remove_identity(e, 1);
945 		break;
946 #endif
947 	case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
948 		process_remove_all_identities(e, 1); /* safe for !WITH_SSH1 */
949 		break;
950 	/* ssh2 */
951 	case SSH2_AGENTC_SIGN_REQUEST:
952 		process_sign_request2(e);
953 		break;
954 	case SSH2_AGENTC_REQUEST_IDENTITIES:
955 		process_request_identities(e, 2);
956 		break;
957 	case SSH2_AGENTC_ADD_IDENTITY:
958 	case SSH2_AGENTC_ADD_ID_CONSTRAINED:
959 		process_add_identity(e, 2);
960 		break;
961 	case SSH2_AGENTC_REMOVE_IDENTITY:
962 		process_remove_identity(e, 2);
963 		break;
964 	case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
965 		process_remove_all_identities(e, 2);
966 		break;
967 #ifdef ENABLE_PKCS11
968 	case SSH_AGENTC_ADD_SMARTCARD_KEY:
969 	case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
970 		process_add_smartcard_key(e);
971 		break;
972 	case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
973 		process_remove_smartcard_key(e);
974 		break;
975 #endif /* ENABLE_PKCS11 */
976 	default:
977 		/* Unknown message.  Respond with failure. */
978 		error("Unknown message %d", type);
979 		sshbuf_reset(e->request);
980 		send_status(e, 0);
981 		break;
982 	}
983 }
984 
985 static void
986 new_socket(sock_type type, int fd)
987 {
988 	u_int i, old_alloc, new_alloc;
989 
990 	if (type == AUTH_CONNECTION) {
991 		debug("xcount %d -> %d", xcount, xcount + 1);
992 		++xcount;
993 	}
994 	set_nonblock(fd);
995 
996 	if (fd > max_fd)
997 		max_fd = fd;
998 
999 	for (i = 0; i < sockets_alloc; i++)
1000 		if (sockets[i].type == AUTH_UNUSED) {
1001 			sockets[i].fd = fd;
1002 			if ((sockets[i].input = sshbuf_new()) == NULL)
1003 				fatal("%s: sshbuf_new failed", __func__);
1004 			if ((sockets[i].output = sshbuf_new()) == NULL)
1005 				fatal("%s: sshbuf_new failed", __func__);
1006 			if ((sockets[i].request = sshbuf_new()) == NULL)
1007 				fatal("%s: sshbuf_new failed", __func__);
1008 			sockets[i].type = type;
1009 			return;
1010 		}
1011 	old_alloc = sockets_alloc;
1012 	new_alloc = sockets_alloc + 10;
1013 	sockets = xreallocarray(sockets, new_alloc, sizeof(sockets[0]));
1014 	for (i = old_alloc; i < new_alloc; i++)
1015 		sockets[i].type = AUTH_UNUSED;
1016 	sockets_alloc = new_alloc;
1017 	sockets[old_alloc].fd = fd;
1018 	if ((sockets[old_alloc].input = sshbuf_new()) == NULL)
1019 		fatal("%s: sshbuf_new failed", __func__);
1020 	if ((sockets[old_alloc].output = sshbuf_new()) == NULL)
1021 		fatal("%s: sshbuf_new failed", __func__);
1022 	if ((sockets[old_alloc].request = sshbuf_new()) == NULL)
1023 		fatal("%s: sshbuf_new failed", __func__);
1024 	sockets[old_alloc].type = type;
1025 }
1026 
1027 static int
1028 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
1029     struct timeval **tvpp)
1030 {
1031 	u_int i, sz;
1032 	int n = 0;
1033 	static struct timeval tv;
1034 	time_t deadline;
1035 
1036 	for (i = 0; i < sockets_alloc; i++) {
1037 		switch (sockets[i].type) {
1038 		case AUTH_SOCKET:
1039 		case AUTH_CONNECTION:
1040 			n = MAX(n, sockets[i].fd);
1041 			break;
1042 		case AUTH_UNUSED:
1043 			break;
1044 		default:
1045 			fatal("Unknown socket type %d", sockets[i].type);
1046 			break;
1047 		}
1048 	}
1049 
1050 	sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
1051 	if (*fdrp == NULL || sz > *nallocp) {
1052 		free(*fdrp);
1053 		free(*fdwp);
1054 		*fdrp = xmalloc(sz);
1055 		*fdwp = xmalloc(sz);
1056 		*nallocp = sz;
1057 	}
1058 	if (n < *fdl)
1059 		debug("XXX shrink: %d < %d", n, *fdl);
1060 	*fdl = n;
1061 	memset(*fdrp, 0, sz);
1062 	memset(*fdwp, 0, sz);
1063 
1064 	for (i = 0; i < sockets_alloc; i++) {
1065 		switch (sockets[i].type) {
1066 		case AUTH_SOCKET:
1067 		case AUTH_CONNECTION:
1068 			FD_SET(sockets[i].fd, *fdrp);
1069 			if (sshbuf_len(sockets[i].output) > 0)
1070 				FD_SET(sockets[i].fd, *fdwp);
1071 			break;
1072 		default:
1073 			break;
1074 		}
1075 	}
1076 	deadline = reaper();
1077 	if (parent_alive_interval != 0)
1078 		deadline = (deadline == 0) ? parent_alive_interval :
1079 		    MIN(deadline, parent_alive_interval);
1080 	if (deadline == 0) {
1081 		*tvpp = NULL;
1082 	} else {
1083 		tv.tv_sec = deadline;
1084 		tv.tv_usec = 0;
1085 		*tvpp = &tv;
1086 	}
1087 	return (1);
1088 }
1089 
1090 static void
1091 after_select(fd_set *readset, fd_set *writeset)
1092 {
1093 	struct sockaddr_un sunaddr;
1094 	socklen_t slen;
1095 	char buf[1024];
1096 	int len, sock, r;
1097 	u_int i, orig_alloc;
1098 	uid_t euid;
1099 	gid_t egid;
1100 
1101 	for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
1102 		switch (sockets[i].type) {
1103 		case AUTH_UNUSED:
1104 			break;
1105 		case AUTH_SOCKET:
1106 			if (FD_ISSET(sockets[i].fd, readset)) {
1107 				slen = sizeof(sunaddr);
1108 				sock = accept(sockets[i].fd,
1109 				    (struct sockaddr *)&sunaddr, &slen);
1110 				if (sock < 0) {
1111 					error("accept from AUTH_SOCKET: %s",
1112 					    strerror(errno));
1113 					break;
1114 				}
1115 				if (getpeereid(sock, &euid, &egid) < 0) {
1116 					error("getpeereid %d failed: %s",
1117 					    sock, strerror(errno));
1118 					close(sock);
1119 					break;
1120 				}
1121 				if ((euid != 0) && (getuid() != euid)) {
1122 					error("uid mismatch: "
1123 					    "peer euid %u != uid %u",
1124 					    (u_int) euid, (u_int) getuid());
1125 					close(sock);
1126 					break;
1127 				}
1128 				new_socket(AUTH_CONNECTION, sock);
1129 			}
1130 			break;
1131 		case AUTH_CONNECTION:
1132 			if (sshbuf_len(sockets[i].output) > 0 &&
1133 			    FD_ISSET(sockets[i].fd, writeset)) {
1134 				len = write(sockets[i].fd,
1135 				    sshbuf_ptr(sockets[i].output),
1136 				    sshbuf_len(sockets[i].output));
1137 				if (len == -1 && (errno == EAGAIN ||
1138 				    errno == EWOULDBLOCK ||
1139 				    errno == EINTR))
1140 					continue;
1141 				if (len <= 0) {
1142 					close_socket(&sockets[i]);
1143 					break;
1144 				}
1145 				if ((r = sshbuf_consume(sockets[i].output,
1146 				    len)) != 0)
1147 					fatal("%s: buffer error: %s",
1148 					    __func__, ssh_err(r));
1149 			}
1150 			if (FD_ISSET(sockets[i].fd, readset)) {
1151 				len = read(sockets[i].fd, buf, sizeof(buf));
1152 				if (len == -1 && (errno == EAGAIN ||
1153 				    errno == EWOULDBLOCK ||
1154 				    errno == EINTR))
1155 					continue;
1156 				if (len <= 0) {
1157 					close_socket(&sockets[i]);
1158 					break;
1159 				}
1160 				if ((r = sshbuf_put(sockets[i].input,
1161 				    buf, len)) != 0)
1162 					fatal("%s: buffer error: %s",
1163 					    __func__, ssh_err(r));
1164 				explicit_bzero(buf, sizeof(buf));
1165 				process_message(&sockets[i]);
1166 			}
1167 			break;
1168 		default:
1169 			fatal("Unknown type %d", sockets[i].type);
1170 		}
1171 }
1172 
1173 static void
1174 cleanup_socket(void)
1175 {
1176 	if (cleanup_pid != 0 && getpid() != cleanup_pid)
1177 		return;
1178 	debug("%s: cleanup", __func__);
1179 	if (socket_name[0])
1180 		unlink(socket_name);
1181 	if (socket_dir[0])
1182 		rmdir(socket_dir);
1183 }
1184 
1185 void
1186 cleanup_exit(int i)
1187 {
1188 	cleanup_socket();
1189 	_exit(i);
1190 }
1191 
1192 /*ARGSUSED*/
1193 static void
1194 cleanup_handler(int sig)
1195 {
1196 	cleanup_socket();
1197 #ifdef ENABLE_PKCS11
1198 	pkcs11_terminate();
1199 #endif
1200 	_exit(2);
1201 }
1202 
1203 static void
1204 check_parent_exists(void)
1205 {
1206 	/*
1207 	 * If our parent has exited then getppid() will return (pid_t)1,
1208 	 * so testing for that should be safe.
1209 	 */
1210 	if (parent_pid != -1 && getppid() != parent_pid) {
1211 		/* printf("Parent has died - Authentication agent exiting.\n"); */
1212 		cleanup_socket();
1213 		_exit(2);
1214 	}
1215 }
1216 
1217 static void
1218 usage(void)
1219 {
1220 	fprintf(stderr,
1221 	    "usage: ssh-agent [-c | -s] [-Dd] [-a bind_address] [-E fingerprint_hash]\n"
1222 	    "                 [-P pkcs11_whitelist] [-t life] [command [arg ...]]\n"
1223 	    "       ssh-agent [-c | -s] -k\n");
1224 	fprintf(stderr, "  -x          Exit when the last client disconnects.\n");
1225 	exit(1);
1226 }
1227 
1228 int
1229 main(int ac, char **av)
1230 {
1231 	int c_flag = 0, d_flag = 0, D_flag = 0, k_flag = 0, s_flag = 0;
1232 	int sock, fd, ch, result, saved_errno;
1233 	u_int nalloc;
1234 	char *shell, *format, *pidstr, *agentsocket = NULL;
1235 	fd_set *readsetp = NULL, *writesetp = NULL;
1236 #ifdef HAVE_SETRLIMIT
1237 	struct rlimit rlim;
1238 #endif
1239 	extern int optind;
1240 	extern char *optarg;
1241 	pid_t pid;
1242 	char pidstrbuf[1 + 3 * sizeof pid];
1243 	struct timeval *tvp = NULL;
1244 	size_t len;
1245 	mode_t prev_mask;
1246 
1247 	ssh_malloc_init();	/* must be called before any mallocs */
1248 	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1249 	sanitise_stdfd();
1250 
1251 	/* drop */
1252 	setegid(getgid());
1253 	setgid(getgid());
1254 	setuid(geteuid());
1255 
1256 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1257 	/* Disable ptrace on Linux without sgid bit */
1258 	prctl(PR_SET_DUMPABLE, 0);
1259 #endif
1260 
1261 #ifdef WITH_OPENSSL
1262 	OpenSSL_add_all_algorithms();
1263 #endif
1264 
1265 	__progname = ssh_get_progname(av[0]);
1266 	seed_rng();
1267 
1268 	while ((ch = getopt(ac, av, "cDdksE:a:P:t:x")) != -1) {
1269 		switch (ch) {
1270 		case 'E':
1271 			fingerprint_hash = ssh_digest_alg_by_name(optarg);
1272 			if (fingerprint_hash == -1)
1273 				fatal("Invalid hash algorithm \"%s\"", optarg);
1274 			break;
1275 		case 'c':
1276 			if (s_flag)
1277 				usage();
1278 			c_flag++;
1279 			break;
1280 		case 'k':
1281 			k_flag++;
1282 			break;
1283 		case 'P':
1284 			if (pkcs11_whitelist != NULL)
1285 				fatal("-P option already specified");
1286 			pkcs11_whitelist = xstrdup(optarg);
1287 			break;
1288 		case 's':
1289 			if (c_flag)
1290 				usage();
1291 			s_flag++;
1292 			break;
1293 		case 'd':
1294 			if (d_flag || D_flag)
1295 				usage();
1296 			d_flag++;
1297 			break;
1298 		case 'D':
1299 			if (d_flag || D_flag)
1300 				usage();
1301 			D_flag++;
1302 			break;
1303 		case 'a':
1304 			agentsocket = optarg;
1305 			break;
1306 		case 't':
1307 			if ((lifetime = convtime(optarg)) == -1) {
1308 				fprintf(stderr, "Invalid lifetime\n");
1309 				usage();
1310 			}
1311 			break;
1312 		case 'x':
1313 			xcount = 0;
1314 			break;
1315 		default:
1316 			usage();
1317 		}
1318 	}
1319 	ac -= optind;
1320 	av += optind;
1321 
1322 	if (ac > 0 && (c_flag || k_flag || s_flag || d_flag || D_flag))
1323 		usage();
1324 
1325 	if (pkcs11_whitelist == NULL)
1326 		pkcs11_whitelist = xstrdup(DEFAULT_PKCS11_WHITELIST);
1327 
1328 	if (ac == 0 && !c_flag && !s_flag) {
1329 		shell = getenv("SHELL");
1330 		if (shell != NULL && (len = strlen(shell)) > 2 &&
1331 		    strncmp(shell + len - 3, "csh", 3) == 0)
1332 			c_flag = 1;
1333 	}
1334 	if (k_flag) {
1335 		const char *errstr = NULL;
1336 
1337 		pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1338 		if (pidstr == NULL) {
1339 			fprintf(stderr, "%s not set, cannot kill agent\n",
1340 			    SSH_AGENTPID_ENV_NAME);
1341 			exit(1);
1342 		}
1343 		pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1344 		if (errstr) {
1345 			fprintf(stderr,
1346 			    "%s=\"%s\", which is not a good PID: %s\n",
1347 			    SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1348 			exit(1);
1349 		}
1350 		if (kill(pid, SIGTERM) == -1) {
1351 			perror("kill");
1352 			exit(1);
1353 		}
1354 		format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1355 		printf(format, SSH_AUTHSOCKET_ENV_NAME);
1356 		printf(format, SSH_AGENTPID_ENV_NAME);
1357 		printf("echo Agent pid %ld killed;\n", (long)pid);
1358 		exit(0);
1359 	}
1360 	parent_pid = getpid();
1361 
1362 	if (agentsocket == NULL) {
1363 		/* Create private directory for agent socket */
1364 		mktemp_proto(socket_dir, sizeof(socket_dir));
1365 		if (mkdtemp(socket_dir) == NULL) {
1366 			perror("mkdtemp: private socket dir");
1367 			exit(1);
1368 		}
1369 		snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1370 		    (long)parent_pid);
1371 	} else {
1372 		/* Try to use specified agent socket */
1373 		socket_dir[0] = '\0';
1374 		strlcpy(socket_name, agentsocket, sizeof socket_name);
1375 	}
1376 
1377 	/*
1378 	 * Create socket early so it will exist before command gets run from
1379 	 * the parent.
1380 	 */
1381 	prev_mask = umask(0177);
1382 	sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0);
1383 	if (sock < 0) {
1384 		/* XXX - unix_listener() calls error() not perror() */
1385 		*socket_name = '\0'; /* Don't unlink any existing file */
1386 		cleanup_exit(1);
1387 	}
1388 	umask(prev_mask);
1389 
1390 	/*
1391 	 * Fork, and have the parent execute the command, if any, or present
1392 	 * the socket data.  The child continues as the authentication agent.
1393 	 */
1394 	if (D_flag || d_flag) {
1395 		log_init(__progname,
1396 		    d_flag ? SYSLOG_LEVEL_DEBUG3 : SYSLOG_LEVEL_INFO,
1397 		    SYSLOG_FACILITY_AUTH, 1);
1398 		format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1399 		printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1400 		    SSH_AUTHSOCKET_ENV_NAME);
1401 		printf("echo Agent pid %ld;\n", (long)parent_pid);
1402 		fflush(stdout);
1403 		goto skip;
1404 	}
1405 	pid = fork();
1406 	if (pid == -1) {
1407 		perror("fork");
1408 		cleanup_exit(1);
1409 	}
1410 	if (pid != 0) {		/* Parent - execute the given command. */
1411 		close(sock);
1412 		snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1413 		if (ac == 0) {
1414 			format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1415 			printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1416 			    SSH_AUTHSOCKET_ENV_NAME);
1417 			printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1418 			    SSH_AGENTPID_ENV_NAME);
1419 			printf("echo Agent pid %ld;\n", (long)pid);
1420 			exit(0);
1421 		}
1422 		if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1423 		    setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1424 			perror("setenv");
1425 			exit(1);
1426 		}
1427 		execvp(av[0], av);
1428 		perror(av[0]);
1429 		exit(1);
1430 	}
1431 	/* child */
1432 	log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1433 
1434 	if (setsid() == -1) {
1435 		error("setsid: %s", strerror(errno));
1436 		cleanup_exit(1);
1437 	}
1438 
1439 	(void)chdir("/");
1440 	if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1441 		/* XXX might close listen socket */
1442 		(void)dup2(fd, STDIN_FILENO);
1443 		(void)dup2(fd, STDOUT_FILENO);
1444 		(void)dup2(fd, STDERR_FILENO);
1445 		if (fd > 2)
1446 			close(fd);
1447 	}
1448 
1449 #ifdef HAVE_SETRLIMIT
1450 	/* deny core dumps, since memory contains unencrypted private keys */
1451 	rlim.rlim_cur = rlim.rlim_max = 0;
1452 	if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1453 		error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1454 		cleanup_exit(1);
1455 	}
1456 #endif
1457 
1458 skip:
1459 
1460 	cleanup_pid = getpid();
1461 
1462 #ifdef ENABLE_PKCS11
1463 	pkcs11_init(0);
1464 #endif
1465 	new_socket(AUTH_SOCKET, sock);
1466 	if (ac > 0)
1467 		parent_alive_interval = 10;
1468 	idtab_init();
1469 	signal(SIGPIPE, SIG_IGN);
1470 	signal(SIGINT, (d_flag | D_flag) ? cleanup_handler : SIG_IGN);
1471 	signal(SIGHUP, cleanup_handler);
1472 	signal(SIGTERM, cleanup_handler);
1473 	nalloc = 0;
1474 
1475 	if (pledge("stdio rpath cpath unix id proc exec", NULL) == -1)
1476 		fatal("%s: pledge: %s", __progname, strerror(errno));
1477 	platform_pledge_agent();
1478 
1479 	while (1) {
1480 		prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1481 		result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1482 		saved_errno = errno;
1483 		if (parent_alive_interval != 0)
1484 			check_parent_exists();
1485 		(void) reaper();	/* remove expired keys */
1486 		if (result < 0) {
1487 			if (saved_errno == EINTR)
1488 				continue;
1489 			fatal("select: %s", strerror(saved_errno));
1490 		} else if (result > 0)
1491 			after_select(readsetp, writesetp);
1492 	}
1493 	/* NOTREACHED */
1494 }
1495