2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * Functions for connecting the local authentication agent.
7 * As far as I am concerned, the code I have written for this software
8 * can be used freely for any purpose. Any derived versions of this
9 * software must be clearly marked as such, and if the derived work is
10 * incompatible with the protocol description in the RFC file, it must be
11 * called by a name other than "ssh" or "Secure Shell".
13 * SSH2 implementation,
14 * Copyright (c) 2000 Markus Friedl. All rights reserved.
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
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.
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.
38 RCSID("$OpenBSD: authfd.c,v 1.65 2005/05/24 17:32:43 avsm Exp $");
40 #include <openssl/evp.h>
56 static int agent_present = 0;
59 int decode_reply(int type);
61 /* macro to check for "agent failure" message */
62 #define agent_failed(x) \
63 ((x == SSH_AGENT_FAILURE) || (x == SSH_COM_AGENT2_FAILURE) || \
64 (x == SSH2_AGENT_FAILURE))
67 ssh_agent_present(void)
73 if ((authfd = ssh_get_authentication_socket()) == -1)
76 ssh_close_authentication_socket(authfd);
81 /* Returns the number of the authentication fd, or -1 if there is none. */
84 ssh_get_authentication_socket(void)
86 const char *authsocket;
88 struct sockaddr_un sunaddr;
90 authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
94 sunaddr.sun_family = AF_UNIX;
95 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
97 sock = socket(AF_UNIX, SOCK_STREAM, 0);
102 if (fcntl(sock, F_SETFD, 1) == -1) {
106 if (connect(sock, (struct sockaddr *) &sunaddr, sizeof sunaddr) < 0) {
115 ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply)
121 /* Get the length of the message, and format it in the buffer. */
122 len = buffer_len(request);
125 /* Send the length and then the packet to the agent. */
126 if (atomicio(vwrite, auth->fd, buf, 4) != 4 ||
127 atomicio(vwrite, auth->fd, buffer_ptr(request),
128 buffer_len(request)) != buffer_len(request)) {
129 error("Error writing to authentication socket.");
133 * Wait for response from the agent. First read the length of the
136 if (atomicio(read, auth->fd, buf, 4) != 4) {
137 error("Error reading response length from authentication socket.");
141 /* Extract the length, and check it for sanity. */
142 len = GET_32BIT(buf);
143 if (len > 256 * 1024)
144 fatal("Authentication response too long: %u", len);
146 /* Read the rest of the response in to the buffer. */
152 if (atomicio(read, auth->fd, buf, l) != l) {
153 error("Error reading response from authentication socket.");
156 buffer_append(reply, buf, l);
163 * Closes the agent socket if it should be closed (depends on how it was
164 * obtained). The argument must have been returned by
165 * ssh_get_authentication_socket().
169 ssh_close_authentication_socket(int sock)
171 if (getenv(SSH_AUTHSOCKET_ENV_NAME))
176 * Opens and connects a private socket for communication with the
177 * authentication agent. Returns the file descriptor (which must be
178 * shut down and closed by the caller when no longer needed).
179 * Returns NULL if an error occurred and the connection could not be
183 AuthenticationConnection *
184 ssh_get_authentication_connection(void)
186 AuthenticationConnection *auth;
189 sock = ssh_get_authentication_socket();
192 * Fail if we couldn't obtain a connection. This happens if we
193 * exited due to a timeout.
198 auth = xmalloc(sizeof(*auth));
200 buffer_init(&auth->identities);
207 * Closes the connection to the authentication agent and frees any associated
212 ssh_close_authentication_connection(AuthenticationConnection *auth)
214 buffer_free(&auth->identities);
219 /* Lock/unlock agent */
221 ssh_lock_agent(AuthenticationConnection *auth, int lock, const char *password)
227 buffer_put_char(&msg, lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK);
228 buffer_put_cstring(&msg, password);
230 if (ssh_request_reply(auth, &msg, &msg) == 0) {
234 type = buffer_get_char(&msg);
236 return decode_reply(type);
240 * Returns the first authentication identity held by the agent.
244 ssh_get_num_identities(AuthenticationConnection *auth, int version)
246 int type, code1 = 0, code2 = 0;
251 code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
252 code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
255 code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
256 code2 = SSH2_AGENT_IDENTITIES_ANSWER;
263 * Send a message to the agent requesting for a list of the
264 * identities it can represent.
266 buffer_init(&request);
267 buffer_put_char(&request, code1);
269 buffer_clear(&auth->identities);
270 if (ssh_request_reply(auth, &request, &auth->identities) == 0) {
271 buffer_free(&request);
274 buffer_free(&request);
276 /* Get message type, and verify that we got a proper answer. */
277 type = buffer_get_char(&auth->identities);
278 if (agent_failed(type)) {
280 } else if (type != code2) {
281 fatal("Bad authentication reply message type: %d", type);
284 /* Get the number of entries in the response and check it for sanity. */
285 auth->howmany = buffer_get_int(&auth->identities);
286 if ((u_int)auth->howmany > 1024)
287 fatal("Too many identities in authentication reply: %d",
290 return auth->howmany;
294 ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version)
296 /* get number of identities and return the first entry (if any). */
297 if (ssh_get_num_identities(auth, version) > 0)
298 return ssh_get_next_identity(auth, comment, version);
303 ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version)
310 /* Return failure if no more entries. */
311 if (auth->howmany <= 0)
315 * Get the next entry from the packet. These will abort with a fatal
316 * error if the packet is too short or contains corrupt data.
320 key = key_new(KEY_RSA1);
321 bits = buffer_get_int(&auth->identities);
322 buffer_get_bignum(&auth->identities, key->rsa->e);
323 buffer_get_bignum(&auth->identities, key->rsa->n);
324 *comment = buffer_get_string(&auth->identities, NULL);
325 if (bits != BN_num_bits(key->rsa->n))
326 logit("Warning: identity keysize mismatch: actual %d, announced %u",
327 BN_num_bits(key->rsa->n), bits);
330 blob = buffer_get_string(&auth->identities, &blen);
331 *comment = buffer_get_string(&auth->identities, NULL);
332 key = key_from_blob(blob, blen);
339 /* Decrement the number of remaining entries. */
345 * Generates a random challenge, sends it to the agent, and waits for
346 * response from the agent. Returns true (non-zero) if the agent gave the
347 * correct answer, zero otherwise. Response type selects the style of
348 * response desired, with 0 corresponding to protocol version 1.0 (no longer
349 * supported) and 1 corresponding to protocol version 1.1.
353 ssh_decrypt_challenge(AuthenticationConnection *auth,
354 Key* key, BIGNUM *challenge,
355 u_char session_id[16],
364 if (key->type != KEY_RSA1)
366 if (response_type == 0) {
367 logit("Compatibility with ssh protocol version 1.0 no longer supported.");
370 buffer_init(&buffer);
371 buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE);
372 buffer_put_int(&buffer, BN_num_bits(key->rsa->n));
373 buffer_put_bignum(&buffer, key->rsa->e);
374 buffer_put_bignum(&buffer, key->rsa->n);
375 buffer_put_bignum(&buffer, challenge);
376 buffer_append(&buffer, session_id, 16);
377 buffer_put_int(&buffer, response_type);
379 if (ssh_request_reply(auth, &buffer, &buffer) == 0) {
380 buffer_free(&buffer);
383 type = buffer_get_char(&buffer);
385 if (agent_failed(type)) {
386 logit("Agent admitted failure to authenticate using the key.");
387 } else if (type != SSH_AGENT_RSA_RESPONSE) {
388 fatal("Bad authentication response: %d", type);
392 * Get the response from the packet. This will abort with a
393 * fatal error if the packet is corrupt.
395 for (i = 0; i < 16; i++)
396 response[i] = buffer_get_char(&buffer);
398 buffer_free(&buffer);
402 /* ask agent to sign data, returns -1 on error, 0 on success */
404 ssh_agent_sign(AuthenticationConnection *auth,
406 u_char **sigp, u_int *lenp,
407 u_char *data, u_int datalen)
409 extern int datafellows;
416 if (key_to_blob(key, &blob, &blen) == 0)
419 if (datafellows & SSH_BUG_SIGBLOB)
420 flags = SSH_AGENT_OLD_SIGNATURE;
423 buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
424 buffer_put_string(&msg, blob, blen);
425 buffer_put_string(&msg, data, datalen);
426 buffer_put_int(&msg, flags);
429 if (ssh_request_reply(auth, &msg, &msg) == 0) {
433 type = buffer_get_char(&msg);
434 if (agent_failed(type)) {
435 logit("Agent admitted failure to sign using the key.");
436 } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
437 fatal("Bad authentication response: %d", type);
440 *sigp = buffer_get_string(&msg, lenp);
446 /* Encode key for a message to the agent. */
449 ssh_encode_identity_rsa1(Buffer *b, RSA *key, const char *comment)
451 buffer_put_int(b, BN_num_bits(key->n));
452 buffer_put_bignum(b, key->n);
453 buffer_put_bignum(b, key->e);
454 buffer_put_bignum(b, key->d);
455 /* To keep within the protocol: p < q for ssh. in SSL p > q */
456 buffer_put_bignum(b, key->iqmp); /* ssh key->u */
457 buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
458 buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
459 buffer_put_cstring(b, comment);
463 ssh_encode_identity_ssh2(Buffer *b, Key *key, const char *comment)
465 buffer_put_cstring(b, key_ssh_name(key));
468 buffer_put_bignum2(b, key->rsa->n);
469 buffer_put_bignum2(b, key->rsa->e);
470 buffer_put_bignum2(b, key->rsa->d);
471 buffer_put_bignum2(b, key->rsa->iqmp);
472 buffer_put_bignum2(b, key->rsa->p);
473 buffer_put_bignum2(b, key->rsa->q);
476 buffer_put_bignum2(b, key->dsa->p);
477 buffer_put_bignum2(b, key->dsa->q);
478 buffer_put_bignum2(b, key->dsa->g);
479 buffer_put_bignum2(b, key->dsa->pub_key);
480 buffer_put_bignum2(b, key->dsa->priv_key);
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);
503 SSH_AGENTC_ADD_RSA_ID_CONSTRAINED :
504 SSH_AGENTC_ADD_RSA_IDENTITY;
505 buffer_put_char(&msg, type);
506 ssh_encode_identity_rsa1(&msg, key->rsa, comment);
511 SSH2_AGENTC_ADD_ID_CONSTRAINED :
512 SSH2_AGENTC_ADD_IDENTITY;
513 buffer_put_char(&msg, type);
514 ssh_encode_identity_ssh2(&msg, key, comment);
523 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
524 buffer_put_int(&msg, life);
527 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM);
529 if (ssh_request_reply(auth, &msg, &msg) == 0) {
533 type = buffer_get_char(&msg);
535 return decode_reply(type);
539 ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
541 return ssh_add_identity_constrained(auth, key, comment, 0, 0);
545 * Removes an identity from the authentication server. This call is not
546 * meant to be used by normal applications.
550 ssh_remove_identity(AuthenticationConnection *auth, Key *key)
559 if (key->type == KEY_RSA1) {
560 buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
561 buffer_put_int(&msg, BN_num_bits(key->rsa->n));
562 buffer_put_bignum(&msg, key->rsa->e);
563 buffer_put_bignum(&msg, key->rsa->n);
564 } else if (key->type == KEY_DSA || key->type == KEY_RSA) {
565 key_to_blob(key, &blob, &blen);
566 buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
567 buffer_put_string(&msg, blob, blen);
573 if (ssh_request_reply(auth, &msg, &msg) == 0) {
577 type = buffer_get_char(&msg);
579 return decode_reply(type);
583 ssh_update_card(AuthenticationConnection *auth, int add,
584 const char *reader_id, const char *pin, u_int life, u_int confirm)
587 int type, constrained = (life || confirm);
591 SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED :
592 SSH_AGENTC_ADD_SMARTCARD_KEY;
594 type = SSH_AGENTC_REMOVE_SMARTCARD_KEY;
597 buffer_put_char(&msg, type);
598 buffer_put_cstring(&msg, reader_id);
599 buffer_put_cstring(&msg, pin);
603 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
604 buffer_put_int(&msg, life);
607 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM);
610 if (ssh_request_reply(auth, &msg, &msg) == 0) {
614 type = buffer_get_char(&msg);
616 return decode_reply(type);
620 * Removes all identities from the agent. This call is not meant to be used
621 * by normal applications.
625 ssh_remove_all_identities(AuthenticationConnection *auth, int version)
629 int code = (version==1) ?
630 SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
631 SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
634 buffer_put_char(&msg, code);
636 if (ssh_request_reply(auth, &msg, &msg) == 0) {
640 type = buffer_get_char(&msg);
642 return decode_reply(type);
646 decode_reply(int type)
649 case SSH_AGENT_FAILURE:
650 case SSH_COM_AGENT2_FAILURE:
651 case SSH2_AGENT_FAILURE:
652 logit("SSH_AGENT_FAILURE");
654 case SSH_AGENT_SUCCESS:
657 fatal("Bad response from authentication agent: %d", type);