1 /* $OpenBSD: ssh-agent.c,v 1.199 2015/03/04 21:12:59 djm Exp $ */
2 /*
3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5  *                    All rights reserved
6  * The authentication agent program.
7  *
8  * As far as I am concerned, the code I have written for this software
9  * can be used freely for any purpose.  Any derived versions of this
10  * software must be clearly marked as such, and if the derived work is
11  * incompatible with the protocol description in the RFC file, it must be
12  * called by a name other than "ssh" or "Secure Shell".
13  *
14  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
15  *
16  * Redistribution and use in source and binary forms, with or without
17  * modification, are permitted provided that the following conditions
18  * are met:
19  * 1. Redistributions of source code must retain the above copyright
20  *    notice, this list of conditions and the following disclaimer.
21  * 2. Redistributions in binary form must reproduce the above copyright
22  *    notice, this list of conditions and the following disclaimer in the
23  *    documentation and/or other materials provided with the distribution.
24  *
25  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
26  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
27  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
28  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
29  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
30  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
31  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
32  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
34  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35  */
36 
37 #include "includes.h"
38 
39 #include <sys/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 
72 #include "key.h"	/* XXX for typedef */
73 #include "buffer.h"	/* XXX for typedef */
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 int locked = 0;
144 char *lock_passwd = NULL;
145 
146 extern char *__progname;
147 
148 /* Default lifetime in seconds (0 == forever) */
149 static long lifetime = 0;
150 
151 static int fingerprint_hash = SSH_FP_HASH_DEFAULT;
152 
153 static void
close_socket(SocketEntry * e)154 close_socket(SocketEntry *e)
155 {
156 	close(e->fd);
157 	e->fd = -1;
158 	e->type = AUTH_UNUSED;
159 	sshbuf_free(e->input);
160 	sshbuf_free(e->output);
161 	sshbuf_free(e->request);
162 }
163 
164 static void
idtab_init(void)165 idtab_init(void)
166 {
167 	int i;
168 
169 	for (i = 0; i <=2; i++) {
170 		TAILQ_INIT(&idtable[i].idlist);
171 		idtable[i].nentries = 0;
172 	}
173 }
174 
175 /* return private key table for requested protocol version */
176 static Idtab *
idtab_lookup(int version)177 idtab_lookup(int version)
178 {
179 	if (version < 1 || version > 2)
180 		fatal("internal error, bad protocol version %d", version);
181 	return &idtable[version];
182 }
183 
184 static void
free_identity(Identity * id)185 free_identity(Identity *id)
186 {
187 	sshkey_free(id->key);
188 	free(id->provider);
189 	free(id->comment);
190 	free(id);
191 }
192 
193 /* return matching private key for given public key */
194 static Identity *
lookup_identity(struct sshkey * key,int version)195 lookup_identity(struct sshkey *key, int version)
196 {
197 	Identity *id;
198 
199 	Idtab *tab = idtab_lookup(version);
200 	TAILQ_FOREACH(id, &tab->idlist, next) {
201 		if (sshkey_equal(key, id->key))
202 			return (id);
203 	}
204 	return (NULL);
205 }
206 
207 /* Check confirmation of keysign request */
208 static int
confirm_key(Identity * id)209 confirm_key(Identity *id)
210 {
211 	char *p;
212 	int ret = -1;
213 
214 	p = sshkey_fingerprint(id->key, fingerprint_hash, SSH_FP_DEFAULT);
215 	if (p != NULL &&
216 	    ask_permission("Allow use of key %s?\nKey fingerprint %s.",
217 	    id->comment, p))
218 		ret = 0;
219 	free(p);
220 
221 	return (ret);
222 }
223 
224 static void
send_status(SocketEntry * e,int success)225 send_status(SocketEntry *e, int success)
226 {
227 	int r;
228 
229 	if ((r = sshbuf_put_u32(e->output, 1)) != 0 ||
230 	    (r = sshbuf_put_u8(e->output, success ?
231 	    SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE)) != 0)
232 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
233 }
234 
235 /* send list of supported public keys to 'client' */
236 static void
process_request_identities(SocketEntry * e,int version)237 process_request_identities(SocketEntry *e, int version)
238 {
239 	Idtab *tab = idtab_lookup(version);
240 	Identity *id;
241 	struct sshbuf *msg;
242 	int r;
243 
244 	if ((msg = sshbuf_new()) == NULL)
245 		fatal("%s: sshbuf_new failed", __func__);
246 	if ((r = sshbuf_put_u8(msg, (version == 1) ?
247 	    SSH_AGENT_RSA_IDENTITIES_ANSWER :
248 	    SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
249 	    (r = sshbuf_put_u32(msg, tab->nentries)) != 0)
250 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
251 	TAILQ_FOREACH(id, &tab->idlist, next) {
252 		if (id->key->type == KEY_RSA1) {
253 #ifdef WITH_SSH1
254 			if ((r = sshbuf_put_u32(msg,
255 			    BN_num_bits(id->key->rsa->n))) != 0 ||
256 			    (r = sshbuf_put_bignum1(msg,
257 			    id->key->rsa->e)) != 0 ||
258 			    (r = sshbuf_put_bignum1(msg,
259 			    id->key->rsa->n)) != 0)
260 				fatal("%s: buffer error: %s",
261 				    __func__, ssh_err(r));
262 #endif
263 		} else {
264 			u_char *blob;
265 			size_t blen;
266 
267 			if ((r = sshkey_to_blob(id->key, &blob, &blen)) != 0) {
268 				error("%s: sshkey_to_blob: %s", __func__,
269 				    ssh_err(r));
270 				continue;
271 			}
272 			if ((r = sshbuf_put_string(msg, blob, blen)) != 0)
273 				fatal("%s: buffer error: %s",
274 				    __func__, ssh_err(r));
275 			free(blob);
276 		}
277 		if ((r = sshbuf_put_cstring(msg, id->comment)) != 0)
278 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
279 	}
280 	if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
281 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
282 	sshbuf_free(msg);
283 }
284 
285 #ifdef WITH_SSH1
286 /* ssh1 only */
287 static void
process_authentication_challenge1(SocketEntry * e)288 process_authentication_challenge1(SocketEntry *e)
289 {
290 	u_char buf[32], mdbuf[16], session_id[16];
291 	u_int response_type;
292 	BIGNUM *challenge;
293 	Identity *id;
294 	int r, len;
295 	struct sshbuf *msg;
296 	struct ssh_digest_ctx *md;
297 	struct sshkey *key;
298 
299 	if ((msg = sshbuf_new()) == NULL)
300 		fatal("%s: sshbuf_new failed", __func__);
301 	if ((key = sshkey_new(KEY_RSA1)) == NULL)
302 		fatal("%s: sshkey_new failed", __func__);
303 	if ((challenge = BN_new()) == NULL)
304 		fatal("%s: BN_new failed", __func__);
305 
306 	if ((r = sshbuf_get_u32(e->request, NULL)) != 0 || /* ignored */
307 	    (r = sshbuf_get_bignum1(e->request, key->rsa->e)) != 0 ||
308 	    (r = sshbuf_get_bignum1(e->request, key->rsa->n)) != 0 ||
309 	    (r = sshbuf_get_bignum1(e->request, challenge)))
310 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
311 
312 	/* Only protocol 1.1 is supported */
313 	if (sshbuf_len(e->request) == 0)
314 		goto failure;
315 	if ((r = sshbuf_get(e->request, session_id, sizeof(session_id))) != 0 ||
316 	    (r = sshbuf_get_u32(e->request, &response_type)) != 0)
317 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
318 	if (response_type != 1)
319 		goto failure;
320 
321 	id = lookup_identity(key, 1);
322 	if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
323 		struct sshkey *private = id->key;
324 		/* Decrypt the challenge using the private key. */
325 		if ((r = rsa_private_decrypt(challenge, challenge,
326 		    private->rsa) != 0)) {
327 			fatal("%s: rsa_public_encrypt: %s", __func__,
328 			    ssh_err(r));
329 			goto failure;	/* XXX ? */
330 		}
331 
332 		/* The response is MD5 of decrypted challenge plus session id */
333 		len = BN_num_bytes(challenge);
334 		if (len <= 0 || len > 32) {
335 			logit("%s: bad challenge length %d", __func__, len);
336 			goto failure;
337 		}
338 		memset(buf, 0, 32);
339 		BN_bn2bin(challenge, buf + 32 - len);
340 		if ((md = ssh_digest_start(SSH_DIGEST_MD5)) == NULL ||
341 		    ssh_digest_update(md, buf, 32) < 0 ||
342 		    ssh_digest_update(md, session_id, 16) < 0 ||
343 		    ssh_digest_final(md, mdbuf, sizeof(mdbuf)) < 0)
344 			fatal("%s: md5 failed", __func__);
345 		ssh_digest_free(md);
346 
347 		/* Send the response. */
348 		if ((r = sshbuf_put_u8(msg, SSH_AGENT_RSA_RESPONSE)) != 0 ||
349 		    (r = sshbuf_put(msg, mdbuf, sizeof(mdbuf))) != 0)
350 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
351 		goto send;
352 	}
353 
354  failure:
355 	/* Unknown identity or protocol error.  Send failure. */
356 	if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
357 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
358  send:
359 	if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
360 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
361 	sshkey_free(key);
362 	BN_clear_free(challenge);
363 	sshbuf_free(msg);
364 }
365 #endif
366 
367 /* ssh2 only */
368 static void
process_sign_request2(SocketEntry * e)369 process_sign_request2(SocketEntry *e)
370 {
371 	u_char *blob, *data, *signature = NULL;
372 	size_t blen, dlen, slen = 0;
373 	u_int compat = 0, flags;
374 	int r, ok = -1;
375 	struct sshbuf *msg;
376 	struct sshkey *key;
377 	struct identity *id;
378 
379 	if ((msg = sshbuf_new()) == NULL)
380 		fatal("%s: sshbuf_new failed", __func__);
381 	if ((r = sshbuf_get_string(e->request, &blob, &blen)) != 0 ||
382 	    (r = sshbuf_get_string(e->request, &data, &dlen)) != 0 ||
383 	    (r = sshbuf_get_u32(e->request, &flags)) != 0)
384 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
385 	if (flags & SSH_AGENT_OLD_SIGNATURE)
386 		compat = SSH_BUG_SIGBLOB;
387 	if ((r = sshkey_from_blob(blob, blen, &key)) != 0) {
388 		error("%s: cannot parse key blob: %s", __func__, ssh_err(ok));
389 		goto send;
390 	}
391 	if ((id = lookup_identity(key, 2)) == NULL) {
392 		verbose("%s: %s key not found", __func__, sshkey_type(key));
393 		goto send;
394 	}
395 	if (id->confirm && confirm_key(id) != 0) {
396 		verbose("%s: user refused key", __func__);
397 		goto send;
398 	}
399 	if ((r = sshkey_sign(id->key, &signature, &slen,
400 	    data, dlen, compat)) != 0) {
401 		error("%s: sshkey_sign: %s", __func__, ssh_err(ok));
402 		goto send;
403 	}
404 	/* Success */
405 	ok = 0;
406  send:
407 	sshkey_free(key);
408 	if (ok == 0) {
409 		if ((r = sshbuf_put_u8(msg, SSH2_AGENT_SIGN_RESPONSE)) != 0 ||
410 		    (r = sshbuf_put_string(msg, signature, slen)) != 0)
411 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
412 	} else if ((r = sshbuf_put_u8(msg, SSH_AGENT_FAILURE)) != 0)
413 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
414 
415 	if ((r = sshbuf_put_stringb(e->output, msg)) != 0)
416 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
417 
418 	sshbuf_free(msg);
419 	free(data);
420 	free(blob);
421 	free(signature);
422 }
423 
424 /* shared */
425 static void
process_remove_identity(SocketEntry * e,int version)426 process_remove_identity(SocketEntry *e, int version)
427 {
428 	size_t blen;
429 	int r, success = 0;
430 	struct sshkey *key = NULL;
431 	u_char *blob;
432 #ifdef WITH_SSH1
433 	u_int bits;
434 #endif /* WITH_SSH1 */
435 
436 	switch (version) {
437 #ifdef WITH_SSH1
438 	case 1:
439 		if ((key = sshkey_new(KEY_RSA1)) == NULL) {
440 			error("%s: sshkey_new failed", __func__);
441 			return;
442 		}
443 		if ((r = sshbuf_get_u32(e->request, &bits)) != 0 ||
444 		    (r = sshbuf_get_bignum1(e->request, key->rsa->e)) != 0 ||
445 		    (r = sshbuf_get_bignum1(e->request, key->rsa->n)) != 0)
446 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
447 
448 		if (bits != sshkey_size(key))
449 			logit("Warning: identity keysize mismatch: "
450 			    "actual %u, announced %u",
451 			    sshkey_size(key), bits);
452 		break;
453 #endif /* WITH_SSH1 */
454 	case 2:
455 		if ((r = sshbuf_get_string(e->request, &blob, &blen)) != 0)
456 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
457 		if ((r = sshkey_from_blob(blob, blen, &key)) != 0)
458 			error("%s: sshkey_from_blob failed: %s",
459 			    __func__, ssh_err(r));
460 		free(blob);
461 		break;
462 	}
463 	if (key != NULL) {
464 		Identity *id = lookup_identity(key, version);
465 		if (id != NULL) {
466 			/*
467 			 * We have this key.  Free the old key.  Since we
468 			 * don't want to leave empty slots in the middle of
469 			 * the array, we actually free the key there and move
470 			 * all the entries between the empty slot and the end
471 			 * of the array.
472 			 */
473 			Idtab *tab = idtab_lookup(version);
474 			if (tab->nentries < 1)
475 				fatal("process_remove_identity: "
476 				    "internal error: tab->nentries %d",
477 				    tab->nentries);
478 			TAILQ_REMOVE(&tab->idlist, id, next);
479 			free_identity(id);
480 			tab->nentries--;
481 			success = 1;
482 		}
483 		sshkey_free(key);
484 	}
485 	send_status(e, success);
486 }
487 
488 static void
process_remove_all_identities(SocketEntry * e,int version)489 process_remove_all_identities(SocketEntry *e, int version)
490 {
491 	Idtab *tab = idtab_lookup(version);
492 	Identity *id;
493 
494 	/* Loop over all identities and clear the keys. */
495 	for (id = TAILQ_FIRST(&tab->idlist); id;
496 	    id = TAILQ_FIRST(&tab->idlist)) {
497 		TAILQ_REMOVE(&tab->idlist, id, next);
498 		free_identity(id);
499 	}
500 
501 	/* Mark that there are no identities. */
502 	tab->nentries = 0;
503 
504 	/* Send success. */
505 	send_status(e, 1);
506 }
507 
508 /* removes expired keys and returns number of seconds until the next expiry */
509 static time_t
reaper(void)510 reaper(void)
511 {
512 	time_t deadline = 0, now = monotime();
513 	Identity *id, *nxt;
514 	int version;
515 	Idtab *tab;
516 
517 	for (version = 1; version < 3; version++) {
518 		tab = idtab_lookup(version);
519 		for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
520 			nxt = TAILQ_NEXT(id, next);
521 			if (id->death == 0)
522 				continue;
523 			if (now >= id->death) {
524 				debug("expiring key '%s'", id->comment);
525 				TAILQ_REMOVE(&tab->idlist, id, next);
526 				free_identity(id);
527 				tab->nentries--;
528 			} else
529 				deadline = (deadline == 0) ? id->death :
530 				    MIN(deadline, id->death);
531 		}
532 	}
533 	if (deadline == 0 || deadline <= now)
534 		return 0;
535 	else
536 		return (deadline - now);
537 }
538 
539 /*
540  * XXX this and the corresponding serialisation function probably belongs
541  * in key.c
542  */
543 #ifdef WITH_SSH1
544 static int
agent_decode_rsa1(struct sshbuf * m,struct sshkey ** kp)545 agent_decode_rsa1(struct sshbuf *m, struct sshkey **kp)
546 {
547 	struct sshkey *k = NULL;
548 	int r = SSH_ERR_INTERNAL_ERROR;
549 
550 	*kp = NULL;
551 	if ((k = sshkey_new_private(KEY_RSA1)) == NULL)
552 		return SSH_ERR_ALLOC_FAIL;
553 
554 	if ((r = sshbuf_get_u32(m, NULL)) != 0 ||		/* ignored */
555 	    (r = sshbuf_get_bignum1(m, k->rsa->n)) != 0 ||
556 	    (r = sshbuf_get_bignum1(m, k->rsa->e)) != 0 ||
557 	    (r = sshbuf_get_bignum1(m, k->rsa->d)) != 0 ||
558 	    (r = sshbuf_get_bignum1(m, k->rsa->iqmp)) != 0 ||
559 	    /* SSH1 and SSL have p and q swapped */
560 	    (r = sshbuf_get_bignum1(m, k->rsa->q)) != 0 ||	/* p */
561 	    (r = sshbuf_get_bignum1(m, k->rsa->p)) != 0) 	/* q */
562 		goto out;
563 
564 	/* Generate additional parameters */
565 	if ((r = rsa_generate_additional_parameters(k->rsa)) != 0)
566 		goto out;
567 	/* enable blinding */
568 	if (RSA_blinding_on(k->rsa, NULL) != 1) {
569 		r = SSH_ERR_LIBCRYPTO_ERROR;
570 		goto out;
571 	}
572 
573 	r = 0; /* success */
574  out:
575 	if (r == 0)
576 		*kp = k;
577 	else
578 		sshkey_free(k);
579 	return r;
580 }
581 #endif /* WITH_SSH1 */
582 
583 static void
process_add_identity(SocketEntry * e,int version)584 process_add_identity(SocketEntry *e, int version)
585 {
586 	Idtab *tab = idtab_lookup(version);
587 	Identity *id;
588 	int success = 0, confirm = 0;
589 	u_int seconds;
590 	char *comment = NULL;
591 	time_t death = 0;
592 	struct sshkey *k = NULL;
593 	u_char ctype;
594 	int r = SSH_ERR_INTERNAL_ERROR;
595 
596 	switch (version) {
597 #ifdef WITH_SSH1
598 	case 1:
599 		r = agent_decode_rsa1(e->request, &k);
600 		break;
601 #endif /* WITH_SSH1 */
602 	case 2:
603 		r = sshkey_private_deserialize(e->request, &k);
604 		break;
605 	}
606 	if (r != 0 || k == NULL ||
607 	    (r = sshbuf_get_cstring(e->request, &comment, NULL)) != 0) {
608 		error("%s: decode private key: %s", __func__, ssh_err(r));
609 		goto err;
610 	}
611 
612 	while (sshbuf_len(e->request)) {
613 		if ((r = sshbuf_get_u8(e->request, &ctype)) != 0) {
614 			error("%s: buffer error: %s", __func__, ssh_err(r));
615 			goto err;
616 		}
617 		switch (ctype) {
618 		case SSH_AGENT_CONSTRAIN_LIFETIME:
619 			if ((r = sshbuf_get_u32(e->request, &seconds)) != 0) {
620 				error("%s: bad lifetime constraint: %s",
621 				    __func__, ssh_err(r));
622 				goto err;
623 			}
624 			death = monotime() + seconds;
625 			break;
626 		case SSH_AGENT_CONSTRAIN_CONFIRM:
627 			confirm = 1;
628 			break;
629 		default:
630 			error("%s: Unknown constraint %d", __func__, ctype);
631  err:
632 			sshbuf_reset(e->request);
633 			free(comment);
634 			sshkey_free(k);
635 			goto send;
636 		}
637 	}
638 
639 	success = 1;
640 	if (lifetime && !death)
641 		death = monotime() + lifetime;
642 	if ((id = lookup_identity(k, version)) == NULL) {
643 		id = xcalloc(1, sizeof(Identity));
644 		id->key = k;
645 		TAILQ_INSERT_TAIL(&tab->idlist, id, next);
646 		/* Increment the number of identities. */
647 		tab->nentries++;
648 	} else {
649 		sshkey_free(k);
650 		free(id->comment);
651 	}
652 	id->comment = comment;
653 	id->death = death;
654 	id->confirm = confirm;
655 send:
656 	send_status(e, success);
657 }
658 
659 /* XXX todo: encrypt sensitive data with passphrase */
660 static void
process_lock_agent(SocketEntry * e,int lock)661 process_lock_agent(SocketEntry *e, int lock)
662 {
663 	int r, success = 0;
664 	char *passwd;
665 
666 	if ((r = sshbuf_get_cstring(e->request, &passwd, NULL)) != 0)
667 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
668 	if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
669 		locked = 0;
670 		explicit_bzero(lock_passwd, strlen(lock_passwd));
671 		free(lock_passwd);
672 		lock_passwd = NULL;
673 		success = 1;
674 	} else if (!locked && lock) {
675 		locked = 1;
676 		lock_passwd = xstrdup(passwd);
677 		success = 1;
678 	}
679 	explicit_bzero(passwd, strlen(passwd));
680 	free(passwd);
681 	send_status(e, success);
682 }
683 
684 static void
no_identities(SocketEntry * e,u_int type)685 no_identities(SocketEntry *e, u_int type)
686 {
687 	struct sshbuf *msg;
688 	int r;
689 
690 	if ((msg = sshbuf_new()) == NULL)
691 		fatal("%s: sshbuf_new failed", __func__);
692 	if ((r = sshbuf_put_u8(msg,
693 	    (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
694 	    SSH_AGENT_RSA_IDENTITIES_ANSWER :
695 	    SSH2_AGENT_IDENTITIES_ANSWER)) != 0 ||
696 	    (r = sshbuf_put_u32(msg, 0)) != 0 ||
697 	    (r = sshbuf_put_stringb(e->output, msg)) != 0)
698 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
699 	sshbuf_free(msg);
700 }
701 
702 #ifdef ENABLE_PKCS11
703 static void
process_add_smartcard_key(SocketEntry * e)704 process_add_smartcard_key(SocketEntry *e)
705 {
706 	char *provider = NULL, *pin;
707 	int r, i, version, count = 0, success = 0, confirm = 0;
708 	u_int seconds;
709 	time_t death = 0;
710 	u_char type;
711 	struct sshkey **keys = NULL, *k;
712 	Identity *id;
713 	Idtab *tab;
714 
715 	if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
716 	    (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0)
717 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
718 
719 	while (sshbuf_len(e->request)) {
720 		if ((r = sshbuf_get_u8(e->request, &type)) != 0)
721 			fatal("%s: buffer error: %s", __func__, ssh_err(r));
722 		switch (type) {
723 		case SSH_AGENT_CONSTRAIN_LIFETIME:
724 			if ((r = sshbuf_get_u32(e->request, &seconds)) != 0)
725 				fatal("%s: buffer error: %s",
726 				    __func__, ssh_err(r));
727 			death = monotime() + seconds;
728 			break;
729 		case SSH_AGENT_CONSTRAIN_CONFIRM:
730 			confirm = 1;
731 			break;
732 		default:
733 			error("process_add_smartcard_key: "
734 			    "Unknown constraint type %d", type);
735 			goto send;
736 		}
737 	}
738 	if (lifetime && !death)
739 		death = monotime() + lifetime;
740 
741 	count = pkcs11_add_provider(provider, pin, &keys);
742 	for (i = 0; i < count; i++) {
743 		k = keys[i];
744 		version = k->type == KEY_RSA1 ? 1 : 2;
745 		tab = idtab_lookup(version);
746 		if (lookup_identity(k, version) == NULL) {
747 			id = xcalloc(1, sizeof(Identity));
748 			id->key = k;
749 			id->provider = xstrdup(provider);
750 			id->comment = xstrdup(provider); /* XXX */
751 			id->death = death;
752 			id->confirm = confirm;
753 			TAILQ_INSERT_TAIL(&tab->idlist, id, next);
754 			tab->nentries++;
755 			success = 1;
756 		} else {
757 			sshkey_free(k);
758 		}
759 		keys[i] = NULL;
760 	}
761 send:
762 	free(pin);
763 	free(provider);
764 	free(keys);
765 	send_status(e, success);
766 }
767 
768 static void
process_remove_smartcard_key(SocketEntry * e)769 process_remove_smartcard_key(SocketEntry *e)
770 {
771 	char *provider = NULL, *pin = NULL;
772 	int r, version, success = 0;
773 	Identity *id, *nxt;
774 	Idtab *tab;
775 
776 	if ((r = sshbuf_get_cstring(e->request, &provider, NULL)) != 0 ||
777 	    (r = sshbuf_get_cstring(e->request, &pin, NULL)) != 0)
778 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
779 	free(pin);
780 
781 	for (version = 1; version < 3; version++) {
782 		tab = idtab_lookup(version);
783 		for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
784 			nxt = TAILQ_NEXT(id, next);
785 			/* Skip file--based keys */
786 			if (id->provider == NULL)
787 				continue;
788 			if (!strcmp(provider, id->provider)) {
789 				TAILQ_REMOVE(&tab->idlist, id, next);
790 				free_identity(id);
791 				tab->nentries--;
792 			}
793 		}
794 	}
795 	if (pkcs11_del_provider(provider) == 0)
796 		success = 1;
797 	else
798 		error("process_remove_smartcard_key:"
799 		    " pkcs11_del_provider failed");
800 	free(provider);
801 	send_status(e, success);
802 }
803 #endif /* ENABLE_PKCS11 */
804 
805 /* dispatch incoming messages */
806 
807 static void
process_message(SocketEntry * e)808 process_message(SocketEntry *e)
809 {
810 	u_int msg_len;
811 	u_char type;
812 	const u_char *cp;
813 	int r;
814 
815 	if (sshbuf_len(e->input) < 5)
816 		return;		/* Incomplete message. */
817 	cp = sshbuf_ptr(e->input);
818 	msg_len = PEEK_U32(cp);
819 	if (msg_len > 256 * 1024) {
820 		close_socket(e);
821 		return;
822 	}
823 	if (sshbuf_len(e->input) < msg_len + 4)
824 		return;
825 
826 	/* move the current input to e->request */
827 	sshbuf_reset(e->request);
828 	if ((r = sshbuf_get_stringb(e->input, e->request)) != 0 ||
829 	    (r = sshbuf_get_u8(e->request, &type)) != 0)
830 		fatal("%s: buffer error: %s", __func__, ssh_err(r));
831 
832 	/* check wheter agent is locked */
833 	if (locked && type != SSH_AGENTC_UNLOCK) {
834 		sshbuf_reset(e->request);
835 		switch (type) {
836 		case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
837 		case SSH2_AGENTC_REQUEST_IDENTITIES:
838 			/* send empty lists */
839 			no_identities(e, type);
840 			break;
841 		default:
842 			/* send a fail message for all other request types */
843 			send_status(e, 0);
844 		}
845 		return;
846 	}
847 
848 	debug("type %d", type);
849 	switch (type) {
850 	case SSH_AGENTC_LOCK:
851 	case SSH_AGENTC_UNLOCK:
852 		process_lock_agent(e, type == SSH_AGENTC_LOCK);
853 		break;
854 #ifdef WITH_SSH1
855 	/* ssh1 */
856 	case SSH_AGENTC_RSA_CHALLENGE:
857 		process_authentication_challenge1(e);
858 		break;
859 	case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
860 		process_request_identities(e, 1);
861 		break;
862 	case SSH_AGENTC_ADD_RSA_IDENTITY:
863 	case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
864 		process_add_identity(e, 1);
865 		break;
866 	case SSH_AGENTC_REMOVE_RSA_IDENTITY:
867 		process_remove_identity(e, 1);
868 		break;
869 #endif
870 	case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
871 		process_remove_all_identities(e, 1); /* safe for !WITH_SSH1 */
872 		break;
873 	/* ssh2 */
874 	case SSH2_AGENTC_SIGN_REQUEST:
875 		process_sign_request2(e);
876 		break;
877 	case SSH2_AGENTC_REQUEST_IDENTITIES:
878 		process_request_identities(e, 2);
879 		break;
880 	case SSH2_AGENTC_ADD_IDENTITY:
881 	case SSH2_AGENTC_ADD_ID_CONSTRAINED:
882 		process_add_identity(e, 2);
883 		break;
884 	case SSH2_AGENTC_REMOVE_IDENTITY:
885 		process_remove_identity(e, 2);
886 		break;
887 	case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
888 		process_remove_all_identities(e, 2);
889 		break;
890 #ifdef ENABLE_PKCS11
891 	case SSH_AGENTC_ADD_SMARTCARD_KEY:
892 	case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
893 		process_add_smartcard_key(e);
894 		break;
895 	case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
896 		process_remove_smartcard_key(e);
897 		break;
898 #endif /* ENABLE_PKCS11 */
899 	default:
900 		/* Unknown message.  Respond with failure. */
901 		error("Unknown message %d", type);
902 		sshbuf_reset(e->request);
903 		send_status(e, 0);
904 		break;
905 	}
906 }
907 
908 static void
new_socket(sock_type type,int fd)909 new_socket(sock_type type, int fd)
910 {
911 	u_int i, old_alloc, new_alloc;
912 
913 	set_nonblock(fd);
914 
915 	if (fd > max_fd)
916 		max_fd = fd;
917 
918 	for (i = 0; i < sockets_alloc; i++)
919 		if (sockets[i].type == AUTH_UNUSED) {
920 			sockets[i].fd = fd;
921 			if ((sockets[i].input = sshbuf_new()) == NULL)
922 				fatal("%s: sshbuf_new failed", __func__);
923 			if ((sockets[i].output = sshbuf_new()) == NULL)
924 				fatal("%s: sshbuf_new failed", __func__);
925 			if ((sockets[i].request = sshbuf_new()) == NULL)
926 				fatal("%s: sshbuf_new failed", __func__);
927 			sockets[i].type = type;
928 			return;
929 		}
930 	old_alloc = sockets_alloc;
931 	new_alloc = sockets_alloc + 10;
932 	sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
933 	for (i = old_alloc; i < new_alloc; i++)
934 		sockets[i].type = AUTH_UNUSED;
935 	sockets_alloc = new_alloc;
936 	sockets[old_alloc].fd = fd;
937 	if ((sockets[old_alloc].input = sshbuf_new()) == NULL)
938 		fatal("%s: sshbuf_new failed", __func__);
939 	if ((sockets[old_alloc].output = sshbuf_new()) == NULL)
940 		fatal("%s: sshbuf_new failed", __func__);
941 	if ((sockets[old_alloc].request = sshbuf_new()) == NULL)
942 		fatal("%s: sshbuf_new failed", __func__);
943 	sockets[old_alloc].type = type;
944 }
945 
946 static int
prepare_select(fd_set ** fdrp,fd_set ** fdwp,int * fdl,u_int * nallocp,struct timeval ** tvpp)947 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp,
948     struct timeval **tvpp)
949 {
950 	u_int i, sz;
951 	int n = 0;
952 	static struct timeval tv;
953 	time_t deadline;
954 
955 	for (i = 0; i < sockets_alloc; i++) {
956 		switch (sockets[i].type) {
957 		case AUTH_SOCKET:
958 		case AUTH_CONNECTION:
959 			n = MAX(n, sockets[i].fd);
960 			break;
961 		case AUTH_UNUSED:
962 			break;
963 		default:
964 			fatal("Unknown socket type %d", sockets[i].type);
965 			break;
966 		}
967 	}
968 
969 	sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
970 	if (*fdrp == NULL || sz > *nallocp) {
971 		free(*fdrp);
972 		free(*fdwp);
973 		*fdrp = xmalloc(sz);
974 		*fdwp = xmalloc(sz);
975 		*nallocp = sz;
976 	}
977 	if (n < *fdl)
978 		debug("XXX shrink: %d < %d", n, *fdl);
979 	*fdl = n;
980 	memset(*fdrp, 0, sz);
981 	memset(*fdwp, 0, sz);
982 
983 	for (i = 0; i < sockets_alloc; i++) {
984 		switch (sockets[i].type) {
985 		case AUTH_SOCKET:
986 		case AUTH_CONNECTION:
987 			FD_SET(sockets[i].fd, *fdrp);
988 			if (sshbuf_len(sockets[i].output) > 0)
989 				FD_SET(sockets[i].fd, *fdwp);
990 			break;
991 		default:
992 			break;
993 		}
994 	}
995 	deadline = reaper();
996 	if (parent_alive_interval != 0)
997 		deadline = (deadline == 0) ? parent_alive_interval :
998 		    MIN(deadline, parent_alive_interval);
999 	if (deadline == 0) {
1000 		*tvpp = NULL;
1001 	} else {
1002 		tv.tv_sec = deadline;
1003 		tv.tv_usec = 0;
1004 		*tvpp = &tv;
1005 	}
1006 	return (1);
1007 }
1008 
1009 static void
after_select(fd_set * readset,fd_set * writeset)1010 after_select(fd_set *readset, fd_set *writeset)
1011 {
1012 	struct sockaddr_un sunaddr;
1013 	socklen_t slen;
1014 	char buf[1024];
1015 	int len, sock, r;
1016 	u_int i, orig_alloc;
1017 	uid_t euid;
1018 	gid_t egid;
1019 
1020 	for (i = 0, orig_alloc = sockets_alloc; i < orig_alloc; i++)
1021 		switch (sockets[i].type) {
1022 		case AUTH_UNUSED:
1023 			break;
1024 		case AUTH_SOCKET:
1025 			if (FD_ISSET(sockets[i].fd, readset)) {
1026 				slen = sizeof(sunaddr);
1027 				sock = accept(sockets[i].fd,
1028 				    (struct sockaddr *)&sunaddr, &slen);
1029 				if (sock < 0) {
1030 					error("accept from AUTH_SOCKET: %s",
1031 					    strerror(errno));
1032 					break;
1033 				}
1034 				if (getpeereid(sock, &euid, &egid) < 0) {
1035 					error("getpeereid %d failed: %s",
1036 					    sock, strerror(errno));
1037 					close(sock);
1038 					break;
1039 				}
1040 				if ((euid != 0) && (getuid() != euid)) {
1041 					error("uid mismatch: "
1042 					    "peer euid %u != uid %u",
1043 					    (u_int) euid, (u_int) getuid());
1044 					close(sock);
1045 					break;
1046 				}
1047 				new_socket(AUTH_CONNECTION, sock);
1048 			}
1049 			break;
1050 		case AUTH_CONNECTION:
1051 			if (sshbuf_len(sockets[i].output) > 0 &&
1052 			    FD_ISSET(sockets[i].fd, writeset)) {
1053 				len = write(sockets[i].fd,
1054 				    sshbuf_ptr(sockets[i].output),
1055 				    sshbuf_len(sockets[i].output));
1056 				if (len == -1 && (errno == EAGAIN ||
1057 				    errno == EWOULDBLOCK ||
1058 				    errno == EINTR))
1059 					continue;
1060 				if (len <= 0) {
1061 					close_socket(&sockets[i]);
1062 					break;
1063 				}
1064 				if ((r = sshbuf_consume(sockets[i].output,
1065 				    len)) != 0)
1066 					fatal("%s: buffer error: %s",
1067 					    __func__, ssh_err(r));
1068 			}
1069 			if (FD_ISSET(sockets[i].fd, readset)) {
1070 				len = read(sockets[i].fd, buf, sizeof(buf));
1071 				if (len == -1 && (errno == EAGAIN ||
1072 				    errno == EWOULDBLOCK ||
1073 				    errno == EINTR))
1074 					continue;
1075 				if (len <= 0) {
1076 					close_socket(&sockets[i]);
1077 					break;
1078 				}
1079 				if ((r = sshbuf_put(sockets[i].input,
1080 				    buf, len)) != 0)
1081 					fatal("%s: buffer error: %s",
1082 					    __func__, ssh_err(r));
1083 				explicit_bzero(buf, sizeof(buf));
1084 				process_message(&sockets[i]);
1085 			}
1086 			break;
1087 		default:
1088 			fatal("Unknown type %d", sockets[i].type);
1089 		}
1090 }
1091 
1092 static void
cleanup_socket(void)1093 cleanup_socket(void)
1094 {
1095 	if (cleanup_pid != 0 && getpid() != cleanup_pid)
1096 		return;
1097 	debug("%s: cleanup", __func__);
1098 	if (socket_name[0])
1099 		unlink(socket_name);
1100 	if (socket_dir[0])
1101 		rmdir(socket_dir);
1102 }
1103 
1104 void
cleanup_exit(int i)1105 cleanup_exit(int i)
1106 {
1107 	cleanup_socket();
1108 	_exit(i);
1109 }
1110 
1111 /*ARGSUSED*/
1112 static void
cleanup_handler(int sig)1113 cleanup_handler(int sig)
1114 {
1115 	cleanup_socket();
1116 #ifdef ENABLE_PKCS11
1117 	pkcs11_terminate();
1118 #endif
1119 	_exit(2);
1120 }
1121 
1122 static void
check_parent_exists(void)1123 check_parent_exists(void)
1124 {
1125 	/*
1126 	 * If our parent has exited then getppid() will return (pid_t)1,
1127 	 * so testing for that should be safe.
1128 	 */
1129 	if (parent_pid != -1 && getppid() != parent_pid) {
1130 		/* printf("Parent has died - Authentication agent exiting.\n"); */
1131 		cleanup_socket();
1132 		_exit(2);
1133 	}
1134 }
1135 
1136 static void
usage(void)1137 usage(void)
1138 {
1139 	fprintf(stderr,
1140 	    "usage: ssh-agent [-c | -s] [-d] [-a bind_address] [-E fingerprint_hash]\n"
1141 	    "                 [-t life] [command [arg ...]]\n"
1142 	    "       ssh-agent [-c | -s] -k\n");
1143 	exit(1);
1144 }
1145 
1146 int
main(int ac,char ** av)1147 main(int ac, char **av)
1148 {
1149 	int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1150 	int sock, fd, ch, result, saved_errno;
1151 	u_int nalloc;
1152 	char *shell, *format, *pidstr, *agentsocket = NULL;
1153 	fd_set *readsetp = NULL, *writesetp = NULL;
1154 #ifdef HAVE_SETRLIMIT
1155 	struct rlimit rlim;
1156 #endif
1157 	extern int optind;
1158 	extern char *optarg;
1159 	pid_t pid;
1160 	char pidstrbuf[1 + 3 * sizeof pid];
1161 	struct timeval *tvp = NULL;
1162 	size_t len;
1163 	mode_t prev_mask;
1164 
1165 	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1166 	sanitise_stdfd();
1167 
1168 	/* drop */
1169 	setegid(getgid());
1170 	setgid(getgid());
1171 
1172 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1173 	/* Disable ptrace on Linux without sgid bit */
1174 	prctl(PR_SET_DUMPABLE, 0);
1175 #endif
1176 
1177 #ifdef WITH_OPENSSL
1178 	OpenSSL_add_all_algorithms();
1179 #endif
1180 
1181 	__progname = ssh_get_progname(av[0]);
1182 	seed_rng();
1183 
1184 	while ((ch = getopt(ac, av, "cdksE:a:t:")) != -1) {
1185 		switch (ch) {
1186 		case 'E':
1187 			fingerprint_hash = ssh_digest_alg_by_name(optarg);
1188 			if (fingerprint_hash == -1)
1189 				fatal("Invalid hash algorithm \"%s\"", optarg);
1190 			break;
1191 		case 'c':
1192 			if (s_flag)
1193 				usage();
1194 			c_flag++;
1195 			break;
1196 		case 'k':
1197 			k_flag++;
1198 			break;
1199 		case 's':
1200 			if (c_flag)
1201 				usage();
1202 			s_flag++;
1203 			break;
1204 		case 'd':
1205 			if (d_flag)
1206 				usage();
1207 			d_flag++;
1208 			break;
1209 		case 'a':
1210 			agentsocket = optarg;
1211 			break;
1212 		case 't':
1213 			if ((lifetime = convtime(optarg)) == -1) {
1214 				fprintf(stderr, "Invalid lifetime\n");
1215 				usage();
1216 			}
1217 			break;
1218 		default:
1219 			usage();
1220 		}
1221 	}
1222 	ac -= optind;
1223 	av += optind;
1224 
1225 	if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1226 		usage();
1227 
1228 	if (ac == 0 && !c_flag && !s_flag) {
1229 		shell = getenv("SHELL");
1230 		if (shell != NULL && (len = strlen(shell)) > 2 &&
1231 		    strncmp(shell + len - 3, "csh", 3) == 0)
1232 			c_flag = 1;
1233 	}
1234 	if (k_flag) {
1235 		const char *errstr = NULL;
1236 
1237 		pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1238 		if (pidstr == NULL) {
1239 			fprintf(stderr, "%s not set, cannot kill agent\n",
1240 			    SSH_AGENTPID_ENV_NAME);
1241 			exit(1);
1242 		}
1243 		pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1244 		if (errstr) {
1245 			fprintf(stderr,
1246 			    "%s=\"%s\", which is not a good PID: %s\n",
1247 			    SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1248 			exit(1);
1249 		}
1250 		if (kill(pid, SIGTERM) == -1) {
1251 			perror("kill");
1252 			exit(1);
1253 		}
1254 		format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1255 		printf(format, SSH_AUTHSOCKET_ENV_NAME);
1256 		printf(format, SSH_AGENTPID_ENV_NAME);
1257 		printf("echo Agent pid %ld killed;\n", (long)pid);
1258 		exit(0);
1259 	}
1260 	parent_pid = getpid();
1261 
1262 	if (agentsocket == NULL) {
1263 		/* Create private directory for agent socket */
1264 		mktemp_proto(socket_dir, sizeof(socket_dir));
1265 		if (mkdtemp(socket_dir) == NULL) {
1266 			perror("mkdtemp: private socket dir");
1267 			exit(1);
1268 		}
1269 		snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1270 		    (long)parent_pid);
1271 	} else {
1272 		/* Try to use specified agent socket */
1273 		socket_dir[0] = '\0';
1274 		strlcpy(socket_name, agentsocket, sizeof socket_name);
1275 	}
1276 
1277 	/*
1278 	 * Create socket early so it will exist before command gets run from
1279 	 * the parent.
1280 	 */
1281 	prev_mask = umask(0177);
1282 	sock = unix_listener(socket_name, SSH_LISTEN_BACKLOG, 0);
1283 	if (sock < 0) {
1284 		/* XXX - unix_listener() calls error() not perror() */
1285 		*socket_name = '\0'; /* Don't unlink any existing file */
1286 		cleanup_exit(1);
1287 	}
1288 	umask(prev_mask);
1289 
1290 	/*
1291 	 * Fork, and have the parent execute the command, if any, or present
1292 	 * the socket data.  The child continues as the authentication agent.
1293 	 */
1294 	if (d_flag) {
1295 		log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1296 		format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1297 		printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1298 		    SSH_AUTHSOCKET_ENV_NAME);
1299 		printf("echo Agent pid %ld;\n", (long)parent_pid);
1300 		goto skip;
1301 	}
1302 	pid = fork();
1303 	if (pid == -1) {
1304 		perror("fork");
1305 		cleanup_exit(1);
1306 	}
1307 	if (pid != 0) {		/* Parent - execute the given command. */
1308 		close(sock);
1309 		snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1310 		if (ac == 0) {
1311 			format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1312 			printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1313 			    SSH_AUTHSOCKET_ENV_NAME);
1314 			printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1315 			    SSH_AGENTPID_ENV_NAME);
1316 			printf("echo Agent pid %ld;\n", (long)pid);
1317 			exit(0);
1318 		}
1319 		if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1320 		    setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1321 			perror("setenv");
1322 			exit(1);
1323 		}
1324 		execvp(av[0], av);
1325 		perror(av[0]);
1326 		exit(1);
1327 	}
1328 	/* child */
1329 	log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1330 
1331 	if (setsid() == -1) {
1332 		error("setsid: %s", strerror(errno));
1333 		cleanup_exit(1);
1334 	}
1335 
1336 	(void)chdir("/");
1337 	if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1338 		/* XXX might close listen socket */
1339 		(void)dup2(fd, STDIN_FILENO);
1340 		(void)dup2(fd, STDOUT_FILENO);
1341 		(void)dup2(fd, STDERR_FILENO);
1342 		if (fd > 2)
1343 			close(fd);
1344 	}
1345 
1346 #ifdef HAVE_SETRLIMIT
1347 	/* deny core dumps, since memory contains unencrypted private keys */
1348 	rlim.rlim_cur = rlim.rlim_max = 0;
1349 	if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1350 		error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1351 		cleanup_exit(1);
1352 	}
1353 #endif
1354 
1355 skip:
1356 
1357 	cleanup_pid = getpid();
1358 
1359 #ifdef ENABLE_PKCS11
1360 	pkcs11_init(0);
1361 #endif
1362 	new_socket(AUTH_SOCKET, sock);
1363 	if (ac > 0)
1364 		parent_alive_interval = 10;
1365 	idtab_init();
1366 	signal(SIGPIPE, SIG_IGN);
1367 	signal(SIGINT, d_flag ? cleanup_handler : SIG_IGN);
1368 	signal(SIGHUP, cleanup_handler);
1369 	signal(SIGTERM, cleanup_handler);
1370 	nalloc = 0;
1371 
1372 	while (1) {
1373 		prepare_select(&readsetp, &writesetp, &max_fd, &nalloc, &tvp);
1374 		result = select(max_fd + 1, readsetp, writesetp, NULL, tvp);
1375 		saved_errno = errno;
1376 		if (parent_alive_interval != 0)
1377 			check_parent_exists();
1378 		(void) reaper();	/* remove expired keys */
1379 		if (result < 0) {
1380 			if (saved_errno == EINTR)
1381 				continue;
1382 			fatal("select: %s", strerror(saved_errno));
1383 		} else if (result > 0)
1384 			after_select(readsetp, writesetp);
1385 	}
1386 	/* NOTREACHED */
1387 }
1388