1 /* $OpenBSD: authfd.c,v 1.93 2014/04/29 18:01:49 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 static int agent_present = 0;
67 int decode_reply(int type);
69 /* macro to check for "agent failure" message */
70 #define agent_failed(x) \
71 ((x == SSH_AGENT_FAILURE) || (x == SSH_COM_AGENT2_FAILURE) || \
72 (x == SSH2_AGENT_FAILURE))
75 ssh_agent_present(void)
81 if ((authfd = ssh_get_authentication_socket()) == -1)
84 ssh_close_authentication_socket(authfd);
89 /* Returns the number of the authentication fd, or -1 if there is none. */
92 ssh_get_authentication_socket(void)
94 const char *authsocket;
96 struct sockaddr_un sunaddr;
98 authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
102 memset(&sunaddr, 0, sizeof(sunaddr));
103 sunaddr.sun_family = AF_UNIX;
104 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
106 sock = socket(AF_UNIX, SOCK_STREAM, 0);
111 if (fcntl(sock, F_SETFD, FD_CLOEXEC) == -1) {
115 if (connect(sock, (struct sockaddr *)&sunaddr, sizeof sunaddr) < 0) {
124 ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply)
129 /* Get the length of the message, and format it in the buffer. */
130 len = buffer_len(request);
133 /* Send the length and then the packet to the agent. */
134 if (atomicio(vwrite, auth->fd, buf, 4) != 4 ||
135 atomicio(vwrite, auth->fd, buffer_ptr(request),
136 buffer_len(request)) != buffer_len(request)) {
137 error("Error writing to authentication socket.");
141 * Wait for response from the agent. First read the length of the
144 if (atomicio(read, auth->fd, buf, 4) != 4) {
145 error("Error reading response length from authentication socket.");
149 /* Extract the length, and check it for sanity. */
151 if (len > 256 * 1024)
152 fatal("Authentication response too long: %u", len);
154 /* Read the rest of the response in to the buffer. */
160 if (atomicio(read, auth->fd, buf, l) != l) {
161 error("Error reading response from authentication socket.");
164 buffer_append(reply, buf, l);
171 * Closes the agent socket if it should be closed (depends on how it was
172 * obtained). The argument must have been returned by
173 * ssh_get_authentication_socket().
177 ssh_close_authentication_socket(int sock)
179 if (getenv(SSH_AUTHSOCKET_ENV_NAME))
184 * Opens and connects a private socket for communication with the
185 * authentication agent. Returns the file descriptor (which must be
186 * shut down and closed by the caller when no longer needed).
187 * Returns NULL if an error occurred and the connection could not be
191 AuthenticationConnection *
192 ssh_get_authentication_connection(void)
194 AuthenticationConnection *auth;
197 sock = ssh_get_authentication_socket();
200 * Fail if we couldn't obtain a connection. This happens if we
201 * exited due to a timeout.
206 auth = xcalloc(1, sizeof(*auth));
208 buffer_init(&auth->identities);
215 * Closes the connection to the authentication agent and frees any associated
220 ssh_close_authentication_connection(AuthenticationConnection *auth)
222 buffer_free(&auth->identities);
227 /* Lock/unlock agent */
229 ssh_lock_agent(AuthenticationConnection *auth, int lock, const char *password)
235 buffer_put_char(&msg, lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK);
236 buffer_put_cstring(&msg, password);
238 if (ssh_request_reply(auth, &msg, &msg) == 0) {
242 type = buffer_get_char(&msg);
244 return decode_reply(type);
248 * Returns the first authentication identity held by the agent.
252 ssh_get_num_identities(AuthenticationConnection *auth, int version)
254 int type, code1 = 0, code2 = 0;
259 code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
260 code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
263 code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
264 code2 = SSH2_AGENT_IDENTITIES_ANSWER;
271 * Send a message to the agent requesting for a list of the
272 * identities it can represent.
274 buffer_init(&request);
275 buffer_put_char(&request, code1);
277 buffer_clear(&auth->identities);
278 if (ssh_request_reply(auth, &request, &auth->identities) == 0) {
279 buffer_free(&request);
282 buffer_free(&request);
284 /* Get message type, and verify that we got a proper answer. */
285 type = buffer_get_char(&auth->identities);
286 if (agent_failed(type)) {
288 } else if (type != code2) {
289 fatal("Bad authentication reply message type: %d", type);
292 /* Get the number of entries in the response and check it for sanity. */
293 auth->howmany = buffer_get_int(&auth->identities);
294 if ((u_int)auth->howmany > 1024)
295 fatal("Too many identities in authentication reply: %d",
298 return auth->howmany;
302 ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version)
304 /* get number of identities and return the first entry (if any). */
305 if (ssh_get_num_identities(auth, version) > 0)
306 return ssh_get_next_identity(auth, comment, version);
311 ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version)
321 /* Return failure if no more entries. */
322 if (auth->howmany <= 0)
326 * Get the next entry from the packet. These will abort with a fatal
327 * error if the packet is too short or contains corrupt data.
332 key = key_new(KEY_RSA1);
333 bits = buffer_get_int(&auth->identities);
334 buffer_get_bignum(&auth->identities, key->rsa->e);
335 buffer_get_bignum(&auth->identities, key->rsa->n);
336 *comment = buffer_get_string(&auth->identities, NULL);
337 keybits = BN_num_bits(key->rsa->n);
338 if (keybits < 0 || bits != (u_int)keybits)
339 logit("Warning: identity keysize mismatch: actual %d, announced %u",
340 BN_num_bits(key->rsa->n), bits);
344 blob = buffer_get_string(&auth->identities, &blen);
345 *comment = buffer_get_string(&auth->identities, NULL);
346 key = key_from_blob(blob, blen);
352 /* Decrement the number of remaining entries. */
358 * Generates a random challenge, sends it to the agent, and waits for
359 * response from the agent. Returns true (non-zero) if the agent gave the
360 * correct answer, zero otherwise. Response type selects the style of
361 * response desired, with 0 corresponding to protocol version 1.0 (no longer
362 * supported) and 1 corresponding to protocol version 1.1.
367 ssh_decrypt_challenge(AuthenticationConnection *auth,
368 Key* key, BIGNUM *challenge,
369 u_char session_id[16],
378 if (key->type != KEY_RSA1)
380 if (response_type == 0) {
381 logit("Compatibility with ssh protocol version 1.0 no longer supported.");
384 buffer_init(&buffer);
385 buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE);
386 buffer_put_int(&buffer, BN_num_bits(key->rsa->n));
387 buffer_put_bignum(&buffer, key->rsa->e);
388 buffer_put_bignum(&buffer, key->rsa->n);
389 buffer_put_bignum(&buffer, challenge);
390 buffer_append(&buffer, session_id, 16);
391 buffer_put_int(&buffer, response_type);
393 if (ssh_request_reply(auth, &buffer, &buffer) == 0) {
394 buffer_free(&buffer);
397 type = buffer_get_char(&buffer);
399 if (agent_failed(type)) {
400 logit("Agent admitted failure to authenticate using the key.");
401 } else if (type != SSH_AGENT_RSA_RESPONSE) {
402 fatal("Bad authentication response: %d", type);
406 * Get the response from the packet. This will abort with a
407 * fatal error if the packet is corrupt.
409 for (i = 0; i < 16; i++)
410 response[i] = (u_char)buffer_get_char(&buffer);
412 buffer_free(&buffer);
417 /* ask agent to sign data, returns -1 on error, 0 on success */
419 ssh_agent_sign(AuthenticationConnection *auth,
421 u_char **sigp, u_int *lenp,
422 u_char *data, u_int datalen)
424 extern int datafellows;
431 if (key_to_blob(key, &blob, &blen) == 0)
434 if (datafellows & SSH_BUG_SIGBLOB)
435 flags = SSH_AGENT_OLD_SIGNATURE;
438 buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
439 buffer_put_string(&msg, blob, blen);
440 buffer_put_string(&msg, data, datalen);
441 buffer_put_int(&msg, flags);
444 if (ssh_request_reply(auth, &msg, &msg) == 0) {
448 type = buffer_get_char(&msg);
449 if (agent_failed(type)) {
450 logit("Agent admitted failure to sign using the key.");
451 } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
452 fatal("Bad authentication response: %d", type);
455 *sigp = buffer_get_string(&msg, lenp);
461 /* Encode key for a message to the agent. */
465 ssh_encode_identity_rsa1(Buffer *b, RSA *key, const char *comment)
467 buffer_put_int(b, BN_num_bits(key->n));
468 buffer_put_bignum(b, key->n);
469 buffer_put_bignum(b, key->e);
470 buffer_put_bignum(b, key->d);
471 /* To keep within the protocol: p < q for ssh. in SSL p > q */
472 buffer_put_bignum(b, key->iqmp); /* ssh key->u */
473 buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
474 buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
475 buffer_put_cstring(b, comment);
480 ssh_encode_identity_ssh2(Buffer *b, Key *key, const char *comment)
482 key_private_serialize(key, b);
483 buffer_put_cstring(b, comment);
487 * Adds an identity to the authentication server. This call is not meant to
488 * be used by normal applications.
492 ssh_add_identity_constrained(AuthenticationConnection *auth, Key *key,
493 const char *comment, u_int life, u_int confirm)
496 int type, constrained = (life || confirm);
504 SSH_AGENTC_ADD_RSA_ID_CONSTRAINED :
505 SSH_AGENTC_ADD_RSA_IDENTITY;
506 buffer_put_char(&msg, type);
507 ssh_encode_identity_rsa1(&msg, key->rsa, comment);
513 case KEY_RSA_CERT_V00:
516 case KEY_DSA_CERT_V00:
521 case KEY_ED25519_CERT:
523 SSH2_AGENTC_ADD_ID_CONSTRAINED :
524 SSH2_AGENTC_ADD_IDENTITY;
525 buffer_put_char(&msg, type);
526 ssh_encode_identity_ssh2(&msg, key, comment);
534 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
535 buffer_put_int(&msg, life);
538 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM);
540 if (ssh_request_reply(auth, &msg, &msg) == 0) {
544 type = buffer_get_char(&msg);
546 return decode_reply(type);
550 * Removes an identity from the authentication server. This call is not
551 * meant to be used by normal applications.
555 ssh_remove_identity(AuthenticationConnection *auth, Key *key)
565 if (key->type == KEY_RSA1) {
566 buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
567 buffer_put_int(&msg, BN_num_bits(key->rsa->n));
568 buffer_put_bignum(&msg, key->rsa->e);
569 buffer_put_bignum(&msg, key->rsa->n);
572 if (key->type != KEY_UNSPEC) {
573 key_to_blob(key, &blob, &blen);
574 buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
575 buffer_put_string(&msg, blob, blen);
581 if (ssh_request_reply(auth, &msg, &msg) == 0) {
585 type = buffer_get_char(&msg);
587 return decode_reply(type);
591 ssh_update_card(AuthenticationConnection *auth, int add,
592 const char *reader_id, const char *pin, u_int life, u_int confirm)
595 int type, constrained = (life || confirm);
599 SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED :
600 SSH_AGENTC_ADD_SMARTCARD_KEY;
602 type = SSH_AGENTC_REMOVE_SMARTCARD_KEY;
605 buffer_put_char(&msg, type);
606 buffer_put_cstring(&msg, reader_id);
607 buffer_put_cstring(&msg, pin);
611 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
612 buffer_put_int(&msg, life);
615 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM);
618 if (ssh_request_reply(auth, &msg, &msg) == 0) {
622 type = buffer_get_char(&msg);
624 return decode_reply(type);
628 * Removes all identities from the agent. This call is not meant to be used
629 * by normal applications.
633 ssh_remove_all_identities(AuthenticationConnection *auth, int version)
637 int code = (version==1) ?
638 SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
639 SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
642 buffer_put_char(&msg, code);
644 if (ssh_request_reply(auth, &msg, &msg) == 0) {
648 type = buffer_get_char(&msg);
650 return decode_reply(type);
654 decode_reply(int type)
657 case SSH_AGENT_FAILURE:
658 case SSH_COM_AGENT2_FAILURE:
659 case SSH2_AGENT_FAILURE:
660 logit("SSH_AGENT_FAILURE");
662 case SSH_AGENT_SUCCESS:
665 fatal("Bad response from authentication agent: %d", type);