1 /* $OpenBSD: authfd.c,v 1.100 2015/12/04 16:41:28 markus Exp $ */
3 * Author: Tatu Ylonen <ylo@cs.hut.fi>
4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
6 * Functions for connecting the local authentication agent.
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".
14 * SSH2 implementation,
15 * Copyright (c) 2000 Markus Friedl. All rights reserved.
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
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.
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.
40 #include <sys/types.h>
42 #include <sys/socket.h>
65 #define MAX_AGENT_IDENTITIES 2048 /* Max keys in agent reply */
66 #define MAX_AGENT_REPLY_LEN (256 * 1024) /* Max bytes in agent reply */
68 /* macro to check for "agent failure" message */
69 #define agent_failed(x) \
70 ((x == SSH_AGENT_FAILURE) || \
71 (x == SSH_COM_AGENT2_FAILURE) || \
72 (x == SSH2_AGENT_FAILURE))
74 /* Convert success/failure response from agent to a err.h status */
76 decode_reply(u_char type)
78 if (agent_failed(type))
79 return SSH_ERR_AGENT_FAILURE;
80 else if (type == SSH_AGENT_SUCCESS)
83 return SSH_ERR_INVALID_FORMAT;
86 /* Returns the number of the authentication fd, or -1 if there is none. */
88 ssh_get_authentication_socket(int *fdp)
90 const char *authsocket;
92 struct sockaddr_un sunaddr;
97 authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
99 return SSH_ERR_AGENT_NOT_PRESENT;
101 memset(&sunaddr, 0, sizeof(sunaddr));
102 sunaddr.sun_family = AF_UNIX;
103 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
105 if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
106 return SSH_ERR_SYSTEM_ERROR;
109 if (fcntl(sock, F_SETFD, FD_CLOEXEC) == -1 ||
110 connect(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) {
114 return SSH_ERR_SYSTEM_ERROR;
123 /* Communicate with agent: send request and read reply */
125 ssh_request_reply(int sock, struct sshbuf *request, struct sshbuf *reply)
131 /* Get the length of the message, and format it in the buffer. */
132 len = sshbuf_len(request);
135 /* Send the length and then the packet to the agent. */
136 if (atomicio(vwrite, sock, buf, 4) != 4 ||
137 atomicio(vwrite, sock, (u_char *)sshbuf_ptr(request),
138 sshbuf_len(request)) != sshbuf_len(request))
139 return SSH_ERR_AGENT_COMMUNICATION;
141 * Wait for response from the agent. First read the length of the
144 if (atomicio(read, sock, buf, 4) != 4)
145 return SSH_ERR_AGENT_COMMUNICATION;
147 /* Extract the length, and check it for sanity. */
149 if (len > MAX_AGENT_REPLY_LEN)
150 return SSH_ERR_INVALID_FORMAT;
152 /* Read the rest of the response in to the buffer. */
158 if (atomicio(read, sock, buf, l) != l)
159 return SSH_ERR_AGENT_COMMUNICATION;
160 if ((r = sshbuf_put(reply, buf, l)) != 0)
168 * Closes the agent socket if it should be closed (depends on how it was
169 * obtained). The argument must have been returned by
170 * ssh_get_authentication_socket().
173 ssh_close_authentication_socket(int sock)
175 if (getenv(SSH_AUTHSOCKET_ENV_NAME))
179 /* Lock/unlock agent */
181 ssh_lock_agent(int sock, int lock, const char *password)
184 u_char type = lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK;
187 if ((msg = sshbuf_new()) == NULL)
188 return SSH_ERR_ALLOC_FAIL;
189 if ((r = sshbuf_put_u8(msg, type)) != 0 ||
190 (r = sshbuf_put_cstring(msg, password)) != 0)
192 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
194 if ((r = sshbuf_get_u8(msg, &type)) != 0)
196 r = decode_reply(type);
204 deserialise_identity1(struct sshbuf *ids, struct sshkey **keyp, char **commentp)
209 char *comment = NULL;
211 if ((key = sshkey_new(KEY_RSA1)) == NULL)
212 return SSH_ERR_ALLOC_FAIL;
213 if ((r = sshbuf_get_u32(ids, &bits)) != 0 ||
214 (r = sshbuf_get_bignum1(ids, key->rsa->e)) != 0 ||
215 (r = sshbuf_get_bignum1(ids, key->rsa->n)) != 0 ||
216 (r = sshbuf_get_cstring(ids, &comment, NULL)) != 0)
218 keybits = BN_num_bits(key->rsa->n);
219 /* XXX previously we just warned here. I think we should be strict */
220 if (keybits < 0 || bits != (u_int)keybits) {
221 r = SSH_ERR_KEY_BITS_MISMATCH;
228 if (commentp != NULL) {
241 deserialise_identity2(struct sshbuf *ids, struct sshkey **keyp, char **commentp)
244 char *comment = NULL;
248 if ((r = sshbuf_get_string_direct(ids, &blob, &blen)) != 0 ||
249 (r = sshbuf_get_cstring(ids, &comment, NULL)) != 0)
251 if ((r = sshkey_from_blob(blob, blen, keyp)) != 0)
253 if (commentp != NULL) {
264 * Fetch list of identities held by the agent.
267 ssh_fetch_identitylist(int sock, int version, struct ssh_identitylist **idlp)
269 u_char type, code1 = 0, code2 = 0;
272 struct ssh_identitylist *idl = NULL;
275 /* Determine request and expected response types */
278 code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
279 code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
282 code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
283 code2 = SSH2_AGENT_IDENTITIES_ANSWER;
286 return SSH_ERR_INVALID_ARGUMENT;
290 * Send a message to the agent requesting for a list of the
291 * identities it can represent.
293 if ((msg = sshbuf_new()) == NULL)
294 return SSH_ERR_ALLOC_FAIL;
295 if ((r = sshbuf_put_u8(msg, code1)) != 0)
298 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
301 /* Get message type, and verify that we got a proper answer. */
302 if ((r = sshbuf_get_u8(msg, &type)) != 0)
304 if (agent_failed(type)) {
305 r = SSH_ERR_AGENT_FAILURE;
307 } else if (type != code2) {
308 r = SSH_ERR_INVALID_FORMAT;
312 /* Get the number of entries in the response and check it for sanity. */
313 if ((r = sshbuf_get_u32(msg, &num)) != 0)
315 if (num > MAX_AGENT_IDENTITIES) {
316 r = SSH_ERR_INVALID_FORMAT;
320 r = SSH_ERR_AGENT_NO_IDENTITIES;
324 /* Deserialise the response into a list of keys/comments */
325 if ((idl = calloc(1, sizeof(*idl))) == NULL ||
326 (idl->keys = calloc(num, sizeof(*idl->keys))) == NULL ||
327 (idl->comments = calloc(num, sizeof(*idl->comments))) == NULL) {
328 r = SSH_ERR_ALLOC_FAIL;
331 for (i = 0; i < num;) {
335 if ((r = deserialise_identity1(msg,
336 &(idl->keys[i]), &(idl->comments[i]))) != 0)
341 if ((r = deserialise_identity2(msg,
342 &(idl->keys[i]), &(idl->comments[i]))) != 0) {
343 if (r == SSH_ERR_KEY_TYPE_UNKNOWN) {
344 /* Gracefully skip unknown key types */
361 ssh_free_identitylist(idl);
366 ssh_free_identitylist(struct ssh_identitylist *idl)
372 for (i = 0; i < idl->nkeys; i++) {
373 if (idl->keys != NULL)
374 sshkey_free(idl->keys[i]);
375 if (idl->comments != NULL)
376 free(idl->comments[i]);
382 * Sends a challenge (typically from a server via ssh(1)) to the agent,
383 * and waits for a response from the agent.
384 * Returns true (non-zero) if the agent gave the correct answer, zero
390 ssh_decrypt_challenge(int sock, struct sshkey* key, BIGNUM *challenge,
391 u_char session_id[16], u_char response[16])
397 if (key->type != KEY_RSA1)
398 return SSH_ERR_INVALID_ARGUMENT;
399 if ((msg = sshbuf_new()) == NULL)
400 return SSH_ERR_ALLOC_FAIL;
401 if ((r = sshbuf_put_u8(msg, SSH_AGENTC_RSA_CHALLENGE)) != 0 ||
402 (r = sshbuf_put_u32(msg, BN_num_bits(key->rsa->n))) != 0 ||
403 (r = sshbuf_put_bignum1(msg, key->rsa->e)) != 0 ||
404 (r = sshbuf_put_bignum1(msg, key->rsa->n)) != 0 ||
405 (r = sshbuf_put_bignum1(msg, challenge)) != 0 ||
406 (r = sshbuf_put(msg, session_id, 16)) != 0 ||
407 (r = sshbuf_put_u32(msg, 1)) != 0) /* Response type for proto 1.1 */
409 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
411 if ((r = sshbuf_get_u8(msg, &type)) != 0)
413 if (agent_failed(type)) {
414 r = SSH_ERR_AGENT_FAILURE;
416 } else if (type != SSH_AGENT_RSA_RESPONSE) {
417 r = SSH_ERR_INVALID_FORMAT;
420 if ((r = sshbuf_get(msg, response, 16)) != 0)
429 /* encode signature algoritm in flag bits, so we can keep the msg format */
431 agent_encode_alg(struct sshkey *key, const char *alg)
433 if (alg != NULL && key->type == KEY_RSA) {
434 if (strcmp(alg, "rsa-sha2-256") == 0)
435 return SSH_AGENT_RSA_SHA2_256;
436 else if (strcmp(alg, "rsa-sha2-512") == 0)
437 return SSH_AGENT_RSA_SHA2_512;
442 /* ask agent to sign data, returns err.h code on error, 0 on success */
444 ssh_agent_sign(int sock, struct sshkey *key,
445 u_char **sigp, size_t *lenp,
446 const u_char *data, size_t datalen, const char *alg, u_int compat)
449 u_char *blob = NULL, type;
450 size_t blen = 0, len = 0;
452 int r = SSH_ERR_INTERNAL_ERROR;
457 if (datalen > SSH_KEY_MAX_SIGN_DATA_SIZE)
458 return SSH_ERR_INVALID_ARGUMENT;
459 if (compat & SSH_BUG_SIGBLOB)
460 flags |= SSH_AGENT_OLD_SIGNATURE;
461 if ((msg = sshbuf_new()) == NULL)
462 return SSH_ERR_ALLOC_FAIL;
463 if ((r = sshkey_to_blob(key, &blob, &blen)) != 0)
465 flags |= agent_encode_alg(key, alg);
466 if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 ||
467 (r = sshbuf_put_string(msg, blob, blen)) != 0 ||
468 (r = sshbuf_put_string(msg, data, datalen)) != 0 ||
469 (r = sshbuf_put_u32(msg, flags)) != 0)
471 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
473 if ((r = sshbuf_get_u8(msg, &type)) != 0)
475 if (agent_failed(type)) {
476 r = SSH_ERR_AGENT_FAILURE;
478 } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
479 r = SSH_ERR_INVALID_FORMAT;
482 if ((r = sshbuf_get_string(msg, sigp, &len)) != 0)
488 explicit_bzero(blob, blen);
495 /* Encode key for a message to the agent. */
499 ssh_encode_identity_rsa1(struct sshbuf *b, RSA *key, const char *comment)
503 /* To keep within the protocol: p < q for ssh. in SSL p > q */
504 if ((r = sshbuf_put_u32(b, BN_num_bits(key->n))) != 0 ||
505 (r = sshbuf_put_bignum1(b, key->n)) != 0 ||
506 (r = sshbuf_put_bignum1(b, key->e)) != 0 ||
507 (r = sshbuf_put_bignum1(b, key->d)) != 0 ||
508 (r = sshbuf_put_bignum1(b, key->iqmp)) != 0 ||
509 (r = sshbuf_put_bignum1(b, key->q)) != 0 ||
510 (r = sshbuf_put_bignum1(b, key->p)) != 0 ||
511 (r = sshbuf_put_cstring(b, comment)) != 0)
518 ssh_encode_identity_ssh2(struct sshbuf *b, struct sshkey *key,
523 if ((r = sshkey_private_serialize(key, b)) != 0 ||
524 (r = sshbuf_put_cstring(b, comment)) != 0)
530 encode_constraints(struct sshbuf *m, u_int life, u_int confirm)
535 if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_LIFETIME)) != 0 ||
536 (r = sshbuf_put_u32(m, life)) != 0)
540 if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_CONFIRM)) != 0)
549 * Adds an identity to the authentication server.
550 * This call is intended only for use by ssh-add(1) and like applications.
553 ssh_add_identity_constrained(int sock, struct sshkey *key, const char *comment,
554 u_int life, u_int confirm)
557 int r, constrained = (life || confirm);
560 if ((msg = sshbuf_new()) == NULL)
561 return SSH_ERR_ALLOC_FAIL;
567 SSH_AGENTC_ADD_RSA_ID_CONSTRAINED :
568 SSH_AGENTC_ADD_RSA_IDENTITY;
569 if ((r = sshbuf_put_u8(msg, type)) != 0 ||
570 (r = ssh_encode_identity_rsa1(msg, key->rsa, comment)) != 0)
583 case KEY_ED25519_CERT:
585 SSH2_AGENTC_ADD_ID_CONSTRAINED :
586 SSH2_AGENTC_ADD_IDENTITY;
587 if ((r = sshbuf_put_u8(msg, type)) != 0 ||
588 (r = ssh_encode_identity_ssh2(msg, key, comment)) != 0)
592 r = SSH_ERR_INVALID_ARGUMENT;
596 (r = encode_constraints(msg, life, confirm)) != 0)
598 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
600 if ((r = sshbuf_get_u8(msg, &type)) != 0)
602 r = decode_reply(type);
609 * Removes an identity from the authentication server.
610 * This call is intended only for use by ssh-add(1) and like applications.
613 ssh_remove_identity(int sock, struct sshkey *key)
617 u_char type, *blob = NULL;
620 if ((msg = sshbuf_new()) == NULL)
621 return SSH_ERR_ALLOC_FAIL;
624 if (key->type == KEY_RSA1) {
625 if ((r = sshbuf_put_u8(msg,
626 SSH_AGENTC_REMOVE_RSA_IDENTITY)) != 0 ||
627 (r = sshbuf_put_u32(msg, BN_num_bits(key->rsa->n))) != 0 ||
628 (r = sshbuf_put_bignum1(msg, key->rsa->e)) != 0 ||
629 (r = sshbuf_put_bignum1(msg, key->rsa->n)) != 0)
633 if (key->type != KEY_UNSPEC) {
634 if ((r = sshkey_to_blob(key, &blob, &blen)) != 0)
636 if ((r = sshbuf_put_u8(msg,
637 SSH2_AGENTC_REMOVE_IDENTITY)) != 0 ||
638 (r = sshbuf_put_string(msg, blob, blen)) != 0)
641 r = SSH_ERR_INVALID_ARGUMENT;
644 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
646 if ((r = sshbuf_get_u8(msg, &type)) != 0)
648 r = decode_reply(type);
651 explicit_bzero(blob, blen);
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.
663 ssh_update_card(int sock, int add, const char *reader_id, const char *pin,
664 u_int life, u_int confirm)
667 int r, constrained = (life || confirm);
672 SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED :
673 SSH_AGENTC_ADD_SMARTCARD_KEY;
675 type = SSH_AGENTC_REMOVE_SMARTCARD_KEY;
677 if ((msg = sshbuf_new()) == NULL)
678 return SSH_ERR_ALLOC_FAIL;
679 if ((r = sshbuf_put_u8(msg, type)) != 0 ||
680 (r = sshbuf_put_cstring(msg, reader_id)) != 0 ||
681 (r = sshbuf_put_cstring(msg, pin)) != 0)
684 (r = encode_constraints(msg, life, confirm)) != 0)
686 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
688 if ((r = sshbuf_get_u8(msg, &type)) != 0)
690 r = decode_reply(type);
697 * Removes all identities from the agent.
698 * This call is intended only for use by ssh-add(1) and like applications.
701 ssh_remove_all_identities(int sock, int version)
704 u_char type = (version == 1) ?
705 SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
706 SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
709 if ((msg = sshbuf_new()) == NULL)
710 return SSH_ERR_ALLOC_FAIL;
711 if ((r = sshbuf_put_u8(msg, type)) != 0)
713 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
715 if ((r = sshbuf_get_u8(msg, &type)) != 0)
717 r = decode_reply(type);