xref: /freebsd/crypto/openssh/authfd.c (revision 4d3fc8b0)
1 /* $OpenBSD: authfd.c,v 1.133 2023/03/09 21:06:24 jcs 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  * Functions for connecting the local authentication agent.
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  * SSH2 implementation,
15  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
16  *
17  * Redistribution and use in source and binary forms, with or without
18  * modification, are permitted provided that the following conditions
19  * are met:
20  * 1. Redistributions of source code must retain the above copyright
21  *    notice, this list of conditions and the following disclaimer.
22  * 2. Redistributions in binary form must reproduce the above copyright
23  *    notice, this list of conditions and the following disclaimer in the
24  *    documentation and/or other materials provided with the distribution.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36  */
37 
38 #include "includes.h"
39 
40 #include <sys/types.h>
41 #include <sys/un.h>
42 #include <sys/socket.h>
43 
44 #include <fcntl.h>
45 #include <stdlib.h>
46 #include <signal.h>
47 #include <string.h>
48 #include <stdarg.h>
49 #include <unistd.h>
50 #include <errno.h>
51 
52 #include "xmalloc.h"
53 #include "ssh.h"
54 #include "sshbuf.h"
55 #include "sshkey.h"
56 #include "authfd.h"
57 #include "cipher.h"
58 #include "log.h"
59 #include "atomicio.h"
60 #include "misc.h"
61 #include "ssherr.h"
62 
63 #define MAX_AGENT_IDENTITIES	2048		/* Max keys in agent reply */
64 #define MAX_AGENT_REPLY_LEN	(256 * 1024)	/* Max bytes in agent reply */
65 
66 /* macro to check for "agent failure" message */
67 #define agent_failed(x) \
68     ((x == SSH_AGENT_FAILURE) || \
69     (x == SSH_COM_AGENT2_FAILURE) || \
70     (x == SSH2_AGENT_FAILURE))
71 
72 /* Convert success/failure response from agent to a err.h status */
73 static int
74 decode_reply(u_char type)
75 {
76 	if (agent_failed(type))
77 		return SSH_ERR_AGENT_FAILURE;
78 	else if (type == SSH_AGENT_SUCCESS)
79 		return 0;
80 	else
81 		return SSH_ERR_INVALID_FORMAT;
82 }
83 
84 /*
85  * Opens an authentication socket at the provided path and stores the file
86  * descriptor in fdp. Returns 0 on success and an error on failure.
87  */
88 int
89 ssh_get_authentication_socket_path(const char *authsocket, int *fdp)
90 {
91 	int sock, oerrno;
92 	struct sockaddr_un sunaddr;
93 
94 	debug3_f("path '%s'", authsocket);
95 	memset(&sunaddr, 0, sizeof(sunaddr));
96 	sunaddr.sun_family = AF_UNIX;
97 	strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
98 
99 	if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) == -1)
100 		return SSH_ERR_SYSTEM_ERROR;
101 
102 	/* close on exec */
103 	if (fcntl(sock, F_SETFD, FD_CLOEXEC) == -1 ||
104 	    connect(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) == -1) {
105 		oerrno = errno;
106 		close(sock);
107 		errno = oerrno;
108 		return SSH_ERR_SYSTEM_ERROR;
109 	}
110 	if (fdp != NULL)
111 		*fdp = sock;
112 	else
113 		close(sock);
114 	return 0;
115 }
116 
117 /*
118  * Opens the default authentication socket and stores the file descriptor in
119  * fdp. Returns 0 on success and an error on failure.
120  */
121 int
122 ssh_get_authentication_socket(int *fdp)
123 {
124 	const char *authsocket;
125 
126 	if (fdp != NULL)
127 		*fdp = -1;
128 
129 	authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
130 	if (authsocket == NULL || *authsocket == '\0')
131 		return SSH_ERR_AGENT_NOT_PRESENT;
132 
133 	return ssh_get_authentication_socket_path(authsocket, fdp);
134 }
135 
136 /* Communicate with agent: send request and read reply */
137 static int
138 ssh_request_reply(int sock, struct sshbuf *request, struct sshbuf *reply)
139 {
140 	int r;
141 	size_t l, len;
142 	char buf[1024];
143 
144 	/* Get the length of the message, and format it in the buffer. */
145 	len = sshbuf_len(request);
146 	POKE_U32(buf, len);
147 
148 	/* Send the length and then the packet to the agent. */
149 	if (atomicio(vwrite, sock, buf, 4) != 4 ||
150 	    atomicio(vwrite, sock, sshbuf_mutable_ptr(request),
151 	    sshbuf_len(request)) != sshbuf_len(request))
152 		return SSH_ERR_AGENT_COMMUNICATION;
153 	/*
154 	 * Wait for response from the agent.  First read the length of the
155 	 * response packet.
156 	 */
157 	if (atomicio(read, sock, buf, 4) != 4)
158 	    return SSH_ERR_AGENT_COMMUNICATION;
159 
160 	/* Extract the length, and check it for sanity. */
161 	len = PEEK_U32(buf);
162 	if (len > MAX_AGENT_REPLY_LEN)
163 		return SSH_ERR_INVALID_FORMAT;
164 
165 	/* Read the rest of the response in to the buffer. */
166 	sshbuf_reset(reply);
167 	while (len > 0) {
168 		l = len;
169 		if (l > sizeof(buf))
170 			l = sizeof(buf);
171 		if (atomicio(read, sock, buf, l) != l)
172 			return SSH_ERR_AGENT_COMMUNICATION;
173 		if ((r = sshbuf_put(reply, buf, l)) != 0)
174 			return r;
175 		len -= l;
176 	}
177 	return 0;
178 }
179 
180 /* Communicate with agent: sent request, read and decode status reply */
181 static int
182 ssh_request_reply_decode(int sock, struct sshbuf *request)
183 {
184 	struct sshbuf *reply;
185 	int r;
186 	u_char type;
187 
188 	if ((reply = sshbuf_new()) == NULL)
189 		return SSH_ERR_ALLOC_FAIL;
190 	if ((r = ssh_request_reply(sock, request, reply)) != 0 ||
191 	    (r = sshbuf_get_u8(reply, &type)) != 0 ||
192 	    (r = decode_reply(type)) != 0)
193 		goto out;
194 	/* success */
195 	r = 0;
196  out:
197 	sshbuf_free(reply);
198 	return r;
199 }
200 
201 /*
202  * Closes the agent socket if it should be closed (depends on how it was
203  * obtained).  The argument must have been returned by
204  * ssh_get_authentication_socket().
205  */
206 void
207 ssh_close_authentication_socket(int sock)
208 {
209 	if (getenv(SSH_AUTHSOCKET_ENV_NAME))
210 		close(sock);
211 }
212 
213 /* Lock/unlock agent */
214 int
215 ssh_lock_agent(int sock, int lock, const char *password)
216 {
217 	int r;
218 	u_char type = lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK;
219 	struct sshbuf *msg;
220 
221 	if ((msg = sshbuf_new()) == NULL)
222 		return SSH_ERR_ALLOC_FAIL;
223 	if ((r = sshbuf_put_u8(msg, type)) != 0 ||
224 	    (r = sshbuf_put_cstring(msg, password)) != 0 ||
225 	    (r = ssh_request_reply_decode(sock, msg)) != 0)
226 		goto out;
227 	/* success */
228 	r = 0;
229  out:
230 	sshbuf_free(msg);
231 	return r;
232 }
233 
234 
235 static int
236 deserialise_identity2(struct sshbuf *ids, struct sshkey **keyp, char **commentp)
237 {
238 	int r;
239 	char *comment = NULL;
240 	const u_char *blob;
241 	size_t blen;
242 
243 	if ((r = sshbuf_get_string_direct(ids, &blob, &blen)) != 0 ||
244 	    (r = sshbuf_get_cstring(ids, &comment, NULL)) != 0)
245 		goto out;
246 	if ((r = sshkey_from_blob(blob, blen, keyp)) != 0)
247 		goto out;
248 	if (commentp != NULL) {
249 		*commentp = comment;
250 		comment = NULL;
251 	}
252 	r = 0;
253  out:
254 	free(comment);
255 	return r;
256 }
257 
258 /*
259  * Fetch list of identities held by the agent.
260  */
261 int
262 ssh_fetch_identitylist(int sock, struct ssh_identitylist **idlp)
263 {
264 	u_char type;
265 	u_int32_t num, i;
266 	struct sshbuf *msg;
267 	struct ssh_identitylist *idl = NULL;
268 	int r;
269 
270 	/*
271 	 * Send a message to the agent requesting for a list of the
272 	 * identities it can represent.
273 	 */
274 	if ((msg = sshbuf_new()) == NULL)
275 		return SSH_ERR_ALLOC_FAIL;
276 	if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_REQUEST_IDENTITIES)) != 0)
277 		goto out;
278 
279 	if ((r = ssh_request_reply(sock, msg, msg)) != 0)
280 		goto out;
281 
282 	/* Get message type, and verify that we got a proper answer. */
283 	if ((r = sshbuf_get_u8(msg, &type)) != 0)
284 		goto out;
285 	if (agent_failed(type)) {
286 		r = SSH_ERR_AGENT_FAILURE;
287 		goto out;
288 	} else if (type != SSH2_AGENT_IDENTITIES_ANSWER) {
289 		r = SSH_ERR_INVALID_FORMAT;
290 		goto out;
291 	}
292 
293 	/* Get the number of entries in the response and check it for sanity. */
294 	if ((r = sshbuf_get_u32(msg, &num)) != 0)
295 		goto out;
296 	if (num > MAX_AGENT_IDENTITIES) {
297 		r = SSH_ERR_INVALID_FORMAT;
298 		goto out;
299 	}
300 	if (num == 0) {
301 		r = SSH_ERR_AGENT_NO_IDENTITIES;
302 		goto out;
303 	}
304 
305 	/* Deserialise the response into a list of keys/comments */
306 	if ((idl = calloc(1, sizeof(*idl))) == NULL ||
307 	    (idl->keys = calloc(num, sizeof(*idl->keys))) == NULL ||
308 	    (idl->comments = calloc(num, sizeof(*idl->comments))) == NULL) {
309 		r = SSH_ERR_ALLOC_FAIL;
310 		goto out;
311 	}
312 	for (i = 0; i < num;) {
313 		if ((r = deserialise_identity2(msg, &(idl->keys[i]),
314 		    &(idl->comments[i]))) != 0) {
315 			if (r == SSH_ERR_KEY_TYPE_UNKNOWN) {
316 				/* Gracefully skip unknown key types */
317 				num--;
318 				continue;
319 			} else
320 				goto out;
321 		}
322 		i++;
323 	}
324 	idl->nkeys = num;
325 	*idlp = idl;
326 	idl = NULL;
327 	r = 0;
328  out:
329 	sshbuf_free(msg);
330 	if (idl != NULL)
331 		ssh_free_identitylist(idl);
332 	return r;
333 }
334 
335 void
336 ssh_free_identitylist(struct ssh_identitylist *idl)
337 {
338 	size_t i;
339 
340 	if (idl == NULL)
341 		return;
342 	for (i = 0; i < idl->nkeys; i++) {
343 		if (idl->keys != NULL)
344 			sshkey_free(idl->keys[i]);
345 		if (idl->comments != NULL)
346 			free(idl->comments[i]);
347 	}
348 	free(idl->keys);
349 	free(idl->comments);
350 	free(idl);
351 }
352 
353 /*
354  * Check if the ssh agent has a given key.
355  * Returns 0 if found, or a negative SSH_ERR_* error code on failure.
356  */
357 int
358 ssh_agent_has_key(int sock, const struct sshkey *key)
359 {
360 	int r, ret = SSH_ERR_KEY_NOT_FOUND;
361 	size_t i;
362 	struct ssh_identitylist *idlist = NULL;
363 
364 	if ((r = ssh_fetch_identitylist(sock, &idlist)) != 0) {
365 		return r;
366 	}
367 
368 	for (i = 0; i < idlist->nkeys; i++) {
369 		if (sshkey_equal_public(idlist->keys[i], key)) {
370 			ret = 0;
371 			break;
372 		}
373 	}
374 
375 	ssh_free_identitylist(idlist);
376 	return ret;
377 }
378 
379 /*
380  * Sends a challenge (typically from a server via ssh(1)) to the agent,
381  * and waits for a response from the agent.
382  * Returns true (non-zero) if the agent gave the correct answer, zero
383  * otherwise.
384  */
385 
386 
387 /* encode signature algorithm in flag bits, so we can keep the msg format */
388 static u_int
389 agent_encode_alg(const struct sshkey *key, const char *alg)
390 {
391 	if (alg != NULL && sshkey_type_plain(key->type) == KEY_RSA) {
392 		if (strcmp(alg, "rsa-sha2-256") == 0 ||
393 		    strcmp(alg, "rsa-sha2-256-cert-v01@openssh.com") == 0)
394 			return SSH_AGENT_RSA_SHA2_256;
395 		if (strcmp(alg, "rsa-sha2-512") == 0 ||
396 		    strcmp(alg, "rsa-sha2-512-cert-v01@openssh.com") == 0)
397 			return SSH_AGENT_RSA_SHA2_512;
398 	}
399 	return 0;
400 }
401 
402 /* ask agent to sign data, returns err.h code on error, 0 on success */
403 int
404 ssh_agent_sign(int sock, const struct sshkey *key,
405     u_char **sigp, size_t *lenp,
406     const u_char *data, size_t datalen, const char *alg, u_int compat)
407 {
408 	struct sshbuf *msg;
409 	u_char *sig = NULL, type = 0;
410 	size_t len = 0;
411 	u_int flags = 0;
412 	int r = SSH_ERR_INTERNAL_ERROR;
413 
414 	*sigp = NULL;
415 	*lenp = 0;
416 
417 	if (datalen > SSH_KEY_MAX_SIGN_DATA_SIZE)
418 		return SSH_ERR_INVALID_ARGUMENT;
419 	if ((msg = sshbuf_new()) == NULL)
420 		return SSH_ERR_ALLOC_FAIL;
421 	flags |= agent_encode_alg(key, alg);
422 	if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 ||
423 	    (r = sshkey_puts(key, msg)) != 0 ||
424 	    (r = sshbuf_put_string(msg, data, datalen)) != 0 ||
425 	    (r = sshbuf_put_u32(msg, flags)) != 0)
426 		goto out;
427 	if ((r = ssh_request_reply(sock, msg, msg)) != 0)
428 		goto out;
429 	if ((r = sshbuf_get_u8(msg, &type)) != 0)
430 		goto out;
431 	if (agent_failed(type)) {
432 		r = SSH_ERR_AGENT_FAILURE;
433 		goto out;
434 	} else if (type != SSH2_AGENT_SIGN_RESPONSE) {
435 		r = SSH_ERR_INVALID_FORMAT;
436 		goto out;
437 	}
438 	if ((r = sshbuf_get_string(msg, &sig, &len)) != 0)
439 		goto out;
440 	/* Check what we actually got back from the agent. */
441 	if ((r = sshkey_check_sigtype(sig, len, alg)) != 0)
442 		goto out;
443 	/* success */
444 	*sigp = sig;
445 	*lenp = len;
446 	sig = NULL;
447 	len = 0;
448 	r = 0;
449  out:
450 	freezero(sig, len);
451 	sshbuf_free(msg);
452 	return r;
453 }
454 
455 /* Encode key for a message to the agent. */
456 
457 static int
458 encode_dest_constraint_hop(struct sshbuf *m,
459     const struct dest_constraint_hop *dch)
460 {
461 	struct sshbuf *b;
462 	u_int i;
463 	int r;
464 
465 	if ((b = sshbuf_new()) == NULL)
466 		return SSH_ERR_ALLOC_FAIL;
467 	if ((r = sshbuf_put_cstring(b, dch->user)) != 0 ||
468 	    (r = sshbuf_put_cstring(b, dch->hostname)) != 0 ||
469 	    (r = sshbuf_put_string(b, NULL, 0)) != 0) /* reserved */
470 		goto out;
471 	for (i = 0; i < dch->nkeys; i++) {
472 		if ((r = sshkey_puts(dch->keys[i], b)) != 0 ||
473 		    (r = sshbuf_put_u8(b, dch->key_is_ca[i] != 0)) != 0)
474 			goto out;
475 	}
476 	if ((r = sshbuf_put_stringb(m, b)) != 0)
477 		goto out;
478 	/* success */
479 	r = 0;
480  out:
481 	sshbuf_free(b);
482 	return r;
483 }
484 
485 static int
486 encode_dest_constraint(struct sshbuf *m, const struct dest_constraint *dc)
487 {
488 	struct sshbuf *b;
489 	int r;
490 
491 	if ((b = sshbuf_new()) == NULL)
492 		return SSH_ERR_ALLOC_FAIL;
493 	if ((r = encode_dest_constraint_hop(b, &dc->from)) != 0 ||
494 	    (r = encode_dest_constraint_hop(b, &dc->to)) != 0 ||
495 	    (r = sshbuf_put_string(b, NULL, 0)) != 0) /* reserved */
496 		goto out;
497 	if ((r = sshbuf_put_stringb(m, b)) != 0)
498 		goto out;
499 	/* success */
500 	r = 0;
501  out:
502 	sshbuf_free(b);
503 	return r;
504 }
505 
506 static int
507 encode_constraints(struct sshbuf *m, u_int life, u_int confirm, u_int maxsign,
508     const char *provider, struct dest_constraint **dest_constraints,
509     size_t ndest_constraints)
510 {
511 	int r;
512 	struct sshbuf *b = NULL;
513 	size_t i;
514 
515 	if (life != 0) {
516 		if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_LIFETIME)) != 0 ||
517 		    (r = sshbuf_put_u32(m, life)) != 0)
518 			goto out;
519 	}
520 	if (confirm != 0) {
521 		if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_CONFIRM)) != 0)
522 			goto out;
523 	}
524 	if (maxsign != 0) {
525 		if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_MAXSIGN)) != 0 ||
526 		    (r = sshbuf_put_u32(m, maxsign)) != 0)
527 			goto out;
528 	}
529 	if (provider != NULL) {
530 		if ((r = sshbuf_put_u8(m,
531 		    SSH_AGENT_CONSTRAIN_EXTENSION)) != 0 ||
532 		    (r = sshbuf_put_cstring(m,
533 		    "sk-provider@openssh.com")) != 0 ||
534 		    (r = sshbuf_put_cstring(m, provider)) != 0)
535 			goto out;
536 	}
537 	if (dest_constraints != NULL && ndest_constraints > 0) {
538 		if ((b = sshbuf_new()) == NULL) {
539 			r = SSH_ERR_ALLOC_FAIL;
540 			goto out;
541 		}
542 		for (i = 0; i < ndest_constraints; i++) {
543 			if ((r = encode_dest_constraint(b,
544 			    dest_constraints[i])) != 0)
545 				goto out;
546 		}
547 		if ((r = sshbuf_put_u8(m,
548 		    SSH_AGENT_CONSTRAIN_EXTENSION)) != 0 ||
549 		    (r = sshbuf_put_cstring(m,
550 		    "restrict-destination-v00@openssh.com")) != 0 ||
551 		    (r = sshbuf_put_stringb(m, b)) != 0)
552 			goto out;
553 	}
554 	r = 0;
555  out:
556 	sshbuf_free(b);
557 	return r;
558 }
559 
560 /*
561  * Adds an identity to the authentication server.
562  * This call is intended only for use by ssh-add(1) and like applications.
563  */
564 int
565 ssh_add_identity_constrained(int sock, struct sshkey *key,
566     const char *comment, u_int life, u_int confirm, u_int maxsign,
567     const char *provider, struct dest_constraint **dest_constraints,
568     size_t ndest_constraints)
569 {
570 	struct sshbuf *msg;
571 	int r, constrained = (life || confirm || maxsign ||
572 	    provider || dest_constraints);
573 	u_char type;
574 
575 	if ((msg = sshbuf_new()) == NULL)
576 		return SSH_ERR_ALLOC_FAIL;
577 
578 	switch (key->type) {
579 #ifdef WITH_OPENSSL
580 	case KEY_RSA:
581 	case KEY_RSA_CERT:
582 	case KEY_DSA:
583 	case KEY_DSA_CERT:
584 	case KEY_ECDSA:
585 	case KEY_ECDSA_CERT:
586 	case KEY_ECDSA_SK:
587 	case KEY_ECDSA_SK_CERT:
588 #endif
589 	case KEY_ED25519:
590 	case KEY_ED25519_CERT:
591 	case KEY_ED25519_SK:
592 	case KEY_ED25519_SK_CERT:
593 	case KEY_XMSS:
594 	case KEY_XMSS_CERT:
595 		type = constrained ?
596 		    SSH2_AGENTC_ADD_ID_CONSTRAINED :
597 		    SSH2_AGENTC_ADD_IDENTITY;
598 		if ((r = sshbuf_put_u8(msg, type)) != 0 ||
599 		    (r = sshkey_private_serialize_maxsign(key, msg, maxsign,
600 		    0)) != 0 ||
601 		    (r = sshbuf_put_cstring(msg, comment)) != 0)
602 			goto out;
603 		break;
604 	default:
605 		r = SSH_ERR_INVALID_ARGUMENT;
606 		goto out;
607 	}
608 	if (constrained &&
609 	    (r = encode_constraints(msg, life, confirm, maxsign,
610 	    provider, dest_constraints, ndest_constraints)) != 0)
611 		goto out;
612 	if ((r = ssh_request_reply_decode(sock, msg)) != 0)
613 		goto out;
614 	/* success */
615 	r = 0;
616  out:
617 	sshbuf_free(msg);
618 	return r;
619 }
620 
621 /*
622  * Removes an identity from the authentication server.
623  * This call is intended only for use by ssh-add(1) and like applications.
624  */
625 int
626 ssh_remove_identity(int sock, const struct sshkey *key)
627 {
628 	struct sshbuf *msg;
629 	int r;
630 	u_char *blob = NULL;
631 	size_t blen;
632 
633 	if ((msg = sshbuf_new()) == NULL)
634 		return SSH_ERR_ALLOC_FAIL;
635 
636 	if (key->type != KEY_UNSPEC) {
637 		if ((r = sshkey_to_blob(key, &blob, &blen)) != 0)
638 			goto out;
639 		if ((r = sshbuf_put_u8(msg,
640 		    SSH2_AGENTC_REMOVE_IDENTITY)) != 0 ||
641 		    (r = sshbuf_put_string(msg, blob, blen)) != 0)
642 			goto out;
643 	} else {
644 		r = SSH_ERR_INVALID_ARGUMENT;
645 		goto out;
646 	}
647 	if ((r = ssh_request_reply_decode(sock, msg)) != 0)
648 		goto out;
649 	/* success */
650 	r = 0;
651  out:
652 	if (blob != NULL)
653 		freezero(blob, blen);
654 	sshbuf_free(msg);
655 	return r;
656 }
657 
658 /*
659  * Add/remove an token-based identity from the authentication server.
660  * This call is intended only for use by ssh-add(1) and like applications.
661  */
662 int
663 ssh_update_card(int sock, int add, const char *reader_id, const char *pin,
664     u_int life, u_int confirm,
665     struct dest_constraint **dest_constraints, size_t ndest_constraints)
666 {
667 	struct sshbuf *msg;
668 	int r, constrained = (life || confirm || dest_constraints);
669 	u_char type;
670 
671 	if (add) {
672 		type = constrained ?
673 		    SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED :
674 		    SSH_AGENTC_ADD_SMARTCARD_KEY;
675 	} else
676 		type = SSH_AGENTC_REMOVE_SMARTCARD_KEY;
677 
678 	if ((msg = sshbuf_new()) == NULL)
679 		return SSH_ERR_ALLOC_FAIL;
680 	if ((r = sshbuf_put_u8(msg, type)) != 0 ||
681 	    (r = sshbuf_put_cstring(msg, reader_id)) != 0 ||
682 	    (r = sshbuf_put_cstring(msg, pin)) != 0)
683 		goto out;
684 	if (constrained &&
685 	    (r = encode_constraints(msg, life, confirm, 0, NULL,
686 	    dest_constraints, ndest_constraints)) != 0)
687 		goto out;
688 	if ((r = ssh_request_reply_decode(sock, msg)) != 0)
689 		goto out;
690 	/* success */
691 	r = 0;
692  out:
693 	sshbuf_free(msg);
694 	return r;
695 }
696 
697 /*
698  * Removes all identities from the agent.
699  * This call is intended only for use by ssh-add(1) and like applications.
700  *
701  * This supports the SSH protocol 1 message to because, when clearing all
702  * keys from an agent, we generally want to clear both protocol v1 and v2
703  * keys.
704  */
705 int
706 ssh_remove_all_identities(int sock, int version)
707 {
708 	struct sshbuf *msg;
709 	u_char type = (version == 1) ?
710 	    SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
711 	    SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
712 	int r;
713 
714 	if ((msg = sshbuf_new()) == NULL)
715 		return SSH_ERR_ALLOC_FAIL;
716 	if ((r = sshbuf_put_u8(msg, type)) != 0)
717 		goto out;
718 	if ((r = ssh_request_reply_decode(sock, msg)) != 0)
719 		goto out;
720 	/* success */
721 	r = 0;
722  out:
723 	sshbuf_free(msg);
724 	return r;
725 }
726 
727 /* Binds a session ID to a hostkey via the initial KEX signature. */
728 int
729 ssh_agent_bind_hostkey(int sock, const struct sshkey *key,
730     const struct sshbuf *session_id, const struct sshbuf *signature,
731     int forwarding)
732 {
733 	struct sshbuf *msg;
734 	int r;
735 
736 	if (key == NULL || session_id == NULL || signature == NULL)
737 		return SSH_ERR_INVALID_ARGUMENT;
738 	if ((msg = sshbuf_new()) == NULL)
739 		return SSH_ERR_ALLOC_FAIL;
740 	if ((r = sshbuf_put_u8(msg, SSH_AGENTC_EXTENSION)) != 0 ||
741 	    (r = sshbuf_put_cstring(msg, "session-bind@openssh.com")) != 0 ||
742 	    (r = sshkey_puts(key, msg)) != 0 ||
743 	    (r = sshbuf_put_stringb(msg, session_id)) != 0 ||
744 	    (r = sshbuf_put_stringb(msg, signature)) != 0 ||
745 	    (r = sshbuf_put_u8(msg, forwarding ? 1 : 0)) != 0)
746 		goto out;
747 	if ((r = ssh_request_reply_decode(sock, msg)) != 0)
748 		goto out;
749 	/* success */
750 	r = 0;
751  out:
752 	sshbuf_free(msg);
753 	return r;
754 }
755