1 /* $OpenBSD: authfd.c,v 1.108 2018/02/23 15:58:37 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>
64 #define MAX_AGENT_IDENTITIES 2048 /* Max keys in agent reply */
65 #define MAX_AGENT_REPLY_LEN (256 * 1024) /* Max bytes in agent reply */
67 /* macro to check for "agent failure" message */
68 #define agent_failed(x) \
69 ((x == SSH_AGENT_FAILURE) || \
70 (x == SSH_COM_AGENT2_FAILURE) || \
71 (x == SSH2_AGENT_FAILURE))
73 /* Convert success/failure response from agent to a err.h status */
75 decode_reply(u_char type)
77 if (agent_failed(type))
78 return SSH_ERR_AGENT_FAILURE;
79 else if (type == SSH_AGENT_SUCCESS)
82 return SSH_ERR_INVALID_FORMAT;
85 /* Returns the number of the authentication fd, or -1 if there is none. */
87 ssh_get_authentication_socket(int *fdp)
89 const char *authsocket;
91 struct sockaddr_un sunaddr;
96 authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
98 return SSH_ERR_AGENT_NOT_PRESENT;
100 memset(&sunaddr, 0, sizeof(sunaddr));
101 sunaddr.sun_family = AF_UNIX;
102 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
104 if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
105 return SSH_ERR_SYSTEM_ERROR;
108 if (fcntl(sock, F_SETFD, FD_CLOEXEC) == -1 ||
109 connect(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) {
113 return SSH_ERR_SYSTEM_ERROR;
122 /* Communicate with agent: send request and read reply */
124 ssh_request_reply(int sock, struct sshbuf *request, struct sshbuf *reply)
130 /* Get the length of the message, and format it in the buffer. */
131 len = sshbuf_len(request);
134 /* Send the length and then the packet to the agent. */
135 if (atomicio(vwrite, sock, buf, 4) != 4 ||
136 atomicio(vwrite, sock, (u_char *)sshbuf_ptr(request),
137 sshbuf_len(request)) != sshbuf_len(request))
138 return SSH_ERR_AGENT_COMMUNICATION;
140 * Wait for response from the agent. First read the length of the
143 if (atomicio(read, sock, buf, 4) != 4)
144 return SSH_ERR_AGENT_COMMUNICATION;
146 /* Extract the length, and check it for sanity. */
148 if (len > MAX_AGENT_REPLY_LEN)
149 return SSH_ERR_INVALID_FORMAT;
151 /* Read the rest of the response in to the buffer. */
157 if (atomicio(read, sock, buf, l) != l)
158 return SSH_ERR_AGENT_COMMUNICATION;
159 if ((r = sshbuf_put(reply, buf, l)) != 0)
167 * Closes the agent socket if it should be closed (depends on how it was
168 * obtained). The argument must have been returned by
169 * ssh_get_authentication_socket().
172 ssh_close_authentication_socket(int sock)
174 if (getenv(SSH_AUTHSOCKET_ENV_NAME))
178 /* Lock/unlock agent */
180 ssh_lock_agent(int sock, int lock, const char *password)
183 u_char type = lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK;
186 if ((msg = sshbuf_new()) == NULL)
187 return SSH_ERR_ALLOC_FAIL;
188 if ((r = sshbuf_put_u8(msg, type)) != 0 ||
189 (r = sshbuf_put_cstring(msg, password)) != 0)
191 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
193 if ((r = sshbuf_get_u8(msg, &type)) != 0)
195 r = decode_reply(type);
203 deserialise_identity2(struct sshbuf *ids, struct sshkey **keyp, char **commentp)
206 char *comment = NULL;
210 if ((r = sshbuf_get_string_direct(ids, &blob, &blen)) != 0 ||
211 (r = sshbuf_get_cstring(ids, &comment, NULL)) != 0)
213 if ((r = sshkey_from_blob(blob, blen, keyp)) != 0)
215 if (commentp != NULL) {
226 * Fetch list of identities held by the agent.
229 ssh_fetch_identitylist(int sock, struct ssh_identitylist **idlp)
234 struct ssh_identitylist *idl = NULL;
238 * Send a message to the agent requesting for a list of the
239 * identities it can represent.
241 if ((msg = sshbuf_new()) == NULL)
242 return SSH_ERR_ALLOC_FAIL;
243 if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_REQUEST_IDENTITIES)) != 0)
246 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
249 /* Get message type, and verify that we got a proper answer. */
250 if ((r = sshbuf_get_u8(msg, &type)) != 0)
252 if (agent_failed(type)) {
253 r = SSH_ERR_AGENT_FAILURE;
255 } else if (type != SSH2_AGENT_IDENTITIES_ANSWER) {
256 r = SSH_ERR_INVALID_FORMAT;
260 /* Get the number of entries in the response and check it for sanity. */
261 if ((r = sshbuf_get_u32(msg, &num)) != 0)
263 if (num > MAX_AGENT_IDENTITIES) {
264 r = SSH_ERR_INVALID_FORMAT;
268 r = SSH_ERR_AGENT_NO_IDENTITIES;
272 /* Deserialise the response into a list of keys/comments */
273 if ((idl = calloc(1, sizeof(*idl))) == NULL ||
274 (idl->keys = calloc(num, sizeof(*idl->keys))) == NULL ||
275 (idl->comments = calloc(num, sizeof(*idl->comments))) == NULL) {
276 r = SSH_ERR_ALLOC_FAIL;
279 for (i = 0; i < num;) {
280 if ((r = deserialise_identity2(msg, &(idl->keys[i]),
281 &(idl->comments[i]))) != 0) {
282 if (r == SSH_ERR_KEY_TYPE_UNKNOWN) {
283 /* Gracefully skip unknown key types */
298 ssh_free_identitylist(idl);
303 ssh_free_identitylist(struct ssh_identitylist *idl)
309 for (i = 0; i < idl->nkeys; i++) {
310 if (idl->keys != NULL)
311 sshkey_free(idl->keys[i]);
312 if (idl->comments != NULL)
313 free(idl->comments[i]);
319 * Sends a challenge (typically from a server via ssh(1)) to the agent,
320 * and waits for a response from the agent.
321 * Returns true (non-zero) if the agent gave the correct answer, zero
326 /* encode signature algoritm in flag bits, so we can keep the msg format */
328 agent_encode_alg(const struct sshkey *key, const char *alg)
330 if (alg != NULL && key->type == KEY_RSA) {
331 if (strcmp(alg, "rsa-sha2-256") == 0)
332 return SSH_AGENT_RSA_SHA2_256;
333 else if (strcmp(alg, "rsa-sha2-512") == 0)
334 return SSH_AGENT_RSA_SHA2_512;
339 /* ask agent to sign data, returns err.h code on error, 0 on success */
341 ssh_agent_sign(int sock, const struct sshkey *key,
342 u_char **sigp, size_t *lenp,
343 const u_char *data, size_t datalen, const char *alg, u_int compat)
346 u_char *blob = NULL, type;
347 size_t blen = 0, len = 0;
349 int r = SSH_ERR_INTERNAL_ERROR;
354 if (datalen > SSH_KEY_MAX_SIGN_DATA_SIZE)
355 return SSH_ERR_INVALID_ARGUMENT;
356 if ((msg = sshbuf_new()) == NULL)
357 return SSH_ERR_ALLOC_FAIL;
358 if ((r = sshkey_to_blob(key, &blob, &blen)) != 0)
360 flags |= agent_encode_alg(key, alg);
361 if ((r = sshbuf_put_u8(msg, SSH2_AGENTC_SIGN_REQUEST)) != 0 ||
362 (r = sshbuf_put_string(msg, blob, blen)) != 0 ||
363 (r = sshbuf_put_string(msg, data, datalen)) != 0 ||
364 (r = sshbuf_put_u32(msg, flags)) != 0)
366 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
368 if ((r = sshbuf_get_u8(msg, &type)) != 0)
370 if (agent_failed(type)) {
371 r = SSH_ERR_AGENT_FAILURE;
373 } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
374 r = SSH_ERR_INVALID_FORMAT;
377 if ((r = sshbuf_get_string(msg, sigp, &len)) != 0)
383 explicit_bzero(blob, blen);
390 /* Encode key for a message to the agent. */
394 encode_constraints(struct sshbuf *m, u_int life, u_int confirm, u_int maxsign)
399 if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_LIFETIME)) != 0 ||
400 (r = sshbuf_put_u32(m, life)) != 0)
404 if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_CONFIRM)) != 0)
408 if ((r = sshbuf_put_u8(m, SSH_AGENT_CONSTRAIN_MAXSIGN)) != 0 ||
409 (r = sshbuf_put_u32(m, maxsign)) != 0)
418 * Adds an identity to the authentication server.
419 * This call is intended only for use by ssh-add(1) and like applications.
422 ssh_add_identity_constrained(int sock, const struct sshkey *key,
423 const char *comment, u_int life, u_int confirm, u_int maxsign)
426 int r, constrained = (life || confirm || maxsign);
429 if ((msg = sshbuf_new()) == NULL)
430 return SSH_ERR_ALLOC_FAIL;
442 case KEY_ED25519_CERT:
446 SSH2_AGENTC_ADD_ID_CONSTRAINED :
447 SSH2_AGENTC_ADD_IDENTITY;
448 if ((r = sshbuf_put_u8(msg, type)) != 0 ||
449 (r = sshkey_private_serialize_maxsign(key, msg, maxsign,
451 (r = sshbuf_put_cstring(msg, comment)) != 0)
455 r = SSH_ERR_INVALID_ARGUMENT;
459 (r = encode_constraints(msg, life, confirm, maxsign)) != 0)
461 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
463 if ((r = sshbuf_get_u8(msg, &type)) != 0)
465 r = decode_reply(type);
472 * Removes an identity from the authentication server.
473 * This call is intended only for use by ssh-add(1) and like applications.
476 ssh_remove_identity(int sock, struct sshkey *key)
480 u_char type, *blob = NULL;
483 if ((msg = sshbuf_new()) == NULL)
484 return SSH_ERR_ALLOC_FAIL;
486 if (key->type != KEY_UNSPEC) {
487 if ((r = sshkey_to_blob(key, &blob, &blen)) != 0)
489 if ((r = sshbuf_put_u8(msg,
490 SSH2_AGENTC_REMOVE_IDENTITY)) != 0 ||
491 (r = sshbuf_put_string(msg, blob, blen)) != 0)
494 r = SSH_ERR_INVALID_ARGUMENT;
497 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
499 if ((r = sshbuf_get_u8(msg, &type)) != 0)
501 r = decode_reply(type);
504 explicit_bzero(blob, blen);
512 * Add/remove an token-based identity from the authentication server.
513 * This call is intended only for use by ssh-add(1) and like applications.
516 ssh_update_card(int sock, int add, const char *reader_id, const char *pin,
517 u_int life, u_int confirm)
520 int r, constrained = (life || confirm);
525 SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED :
526 SSH_AGENTC_ADD_SMARTCARD_KEY;
528 type = SSH_AGENTC_REMOVE_SMARTCARD_KEY;
530 if ((msg = sshbuf_new()) == NULL)
531 return SSH_ERR_ALLOC_FAIL;
532 if ((r = sshbuf_put_u8(msg, type)) != 0 ||
533 (r = sshbuf_put_cstring(msg, reader_id)) != 0 ||
534 (r = sshbuf_put_cstring(msg, pin)) != 0)
537 (r = encode_constraints(msg, life, confirm, 0)) != 0)
539 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
541 if ((r = sshbuf_get_u8(msg, &type)) != 0)
543 r = decode_reply(type);
550 * Removes all identities from the agent.
551 * This call is intended only for use by ssh-add(1) and like applications.
553 * This supports the SSH protocol 1 message to because, when clearing all
554 * keys from an agent, we generally want to clear both protocol v1 and v2
558 ssh_remove_all_identities(int sock, int version)
561 u_char type = (version == 1) ?
562 SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
563 SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
566 if ((msg = sshbuf_new()) == NULL)
567 return SSH_ERR_ALLOC_FAIL;
568 if ((r = sshbuf_put_u8(msg, type)) != 0)
570 if ((r = ssh_request_reply(sock, msg, msg)) != 0)
572 if ((r = sshbuf_get_u8(msg, &type)) != 0)
574 r = decode_reply(type);