1 /* $OpenBSD: authfd.c,v 1.80 2006/08/03 03:34:41 deraadt 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>
44 #include <openssl/evp.h>
46 #include <openssl/crypto.h>
67 static int agent_present = 0;
70 int decode_reply(int type);
72 /* macro to check for "agent failure" message */
73 #define agent_failed(x) \
74 ((x == SSH_AGENT_FAILURE) || (x == SSH_COM_AGENT2_FAILURE) || \
75 (x == SSH2_AGENT_FAILURE))
78 ssh_agent_present(void)
84 if ((authfd = ssh_get_authentication_socket()) == -1)
87 ssh_close_authentication_socket(authfd);
92 /* Returns the number of the authentication fd, or -1 if there is none. */
95 ssh_get_authentication_socket(void)
97 const char *authsocket;
99 struct sockaddr_un sunaddr;
101 authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
105 sunaddr.sun_family = AF_UNIX;
106 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
108 sock = socket(AF_UNIX, SOCK_STREAM, 0);
113 if (fcntl(sock, F_SETFD, 1) == -1) {
117 if (connect(sock, (struct sockaddr *)&sunaddr, sizeof sunaddr) < 0) {
126 ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply)
131 /* Get the length of the message, and format it in the buffer. */
132 len = buffer_len(request);
135 /* Send the length and then the packet to the agent. */
136 if (atomicio(vwrite, auth->fd, buf, 4) != 4 ||
137 atomicio(vwrite, auth->fd, buffer_ptr(request),
138 buffer_len(request)) != buffer_len(request)) {
139 error("Error writing to authentication socket.");
143 * Wait for response from the agent. First read the length of the
146 if (atomicio(read, auth->fd, buf, 4) != 4) {
147 error("Error reading response length from authentication socket.");
151 /* Extract the length, and check it for sanity. */
153 if (len > 256 * 1024)
154 fatal("Authentication response too long: %u", len);
156 /* Read the rest of the response in to the buffer. */
162 if (atomicio(read, auth->fd, buf, l) != l) {
163 error("Error reading response from authentication socket.");
166 buffer_append(reply, buf, l);
173 * Closes the agent socket if it should be closed (depends on how it was
174 * obtained). The argument must have been returned by
175 * ssh_get_authentication_socket().
179 ssh_close_authentication_socket(int sock)
181 if (getenv(SSH_AUTHSOCKET_ENV_NAME))
186 * Opens and connects a private socket for communication with the
187 * authentication agent. Returns the file descriptor (which must be
188 * shut down and closed by the caller when no longer needed).
189 * Returns NULL if an error occurred and the connection could not be
193 AuthenticationConnection *
194 ssh_get_authentication_connection(void)
196 AuthenticationConnection *auth;
199 sock = ssh_get_authentication_socket();
202 * Fail if we couldn't obtain a connection. This happens if we
203 * exited due to a timeout.
208 auth = xmalloc(sizeof(*auth));
210 buffer_init(&auth->identities);
217 * Closes the connection to the authentication agent and frees any associated
222 ssh_close_authentication_connection(AuthenticationConnection *auth)
224 buffer_free(&auth->identities);
229 /* Lock/unlock agent */
231 ssh_lock_agent(AuthenticationConnection *auth, int lock, const char *password)
237 buffer_put_char(&msg, lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK);
238 buffer_put_cstring(&msg, password);
240 if (ssh_request_reply(auth, &msg, &msg) == 0) {
244 type = buffer_get_char(&msg);
246 return decode_reply(type);
250 * Returns the first authentication identity held by the agent.
254 ssh_get_num_identities(AuthenticationConnection *auth, int version)
256 int type, code1 = 0, code2 = 0;
261 code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
262 code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
265 code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
266 code2 = SSH2_AGENT_IDENTITIES_ANSWER;
273 * Send a message to the agent requesting for a list of the
274 * identities it can represent.
276 buffer_init(&request);
277 buffer_put_char(&request, code1);
279 buffer_clear(&auth->identities);
280 if (ssh_request_reply(auth, &request, &auth->identities) == 0) {
281 buffer_free(&request);
284 buffer_free(&request);
286 /* Get message type, and verify that we got a proper answer. */
287 type = buffer_get_char(&auth->identities);
288 if (agent_failed(type)) {
290 } else if (type != code2) {
291 fatal("Bad authentication reply message type: %d", type);
294 /* Get the number of entries in the response and check it for sanity. */
295 auth->howmany = buffer_get_int(&auth->identities);
296 if ((u_int)auth->howmany > 1024)
297 fatal("Too many identities in authentication reply: %d",
300 return auth->howmany;
304 ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version)
306 /* get number of identities and return the first entry (if any). */
307 if (ssh_get_num_identities(auth, version) > 0)
308 return ssh_get_next_identity(auth, comment, version);
313 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.
331 key = key_new(KEY_RSA1);
332 bits = buffer_get_int(&auth->identities);
333 buffer_get_bignum(&auth->identities, key->rsa->e);
334 buffer_get_bignum(&auth->identities, key->rsa->n);
335 *comment = buffer_get_string(&auth->identities, NULL);
336 keybits = BN_num_bits(key->rsa->n);
337 if (keybits < 0 || bits != (u_int)keybits)
338 logit("Warning: identity keysize mismatch: actual %d, announced %u",
339 BN_num_bits(key->rsa->n), bits);
342 blob = buffer_get_string(&auth->identities, &blen);
343 *comment = buffer_get_string(&auth->identities, NULL);
344 key = key_from_blob(blob, blen);
350 /* Decrement the number of remaining entries. */
356 * Generates a random challenge, sends it to the agent, and waits for
357 * response from the agent. Returns true (non-zero) if the agent gave the
358 * correct answer, zero otherwise. Response type selects the style of
359 * response desired, with 0 corresponding to protocol version 1.0 (no longer
360 * supported) and 1 corresponding to protocol version 1.1.
364 ssh_decrypt_challenge(AuthenticationConnection *auth,
365 Key* key, BIGNUM *challenge,
366 u_char session_id[16],
375 if (key->type != KEY_RSA1)
377 if (response_type == 0) {
378 logit("Compatibility with ssh protocol version 1.0 no longer supported.");
381 buffer_init(&buffer);
382 buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE);
383 buffer_put_int(&buffer, BN_num_bits(key->rsa->n));
384 buffer_put_bignum(&buffer, key->rsa->e);
385 buffer_put_bignum(&buffer, key->rsa->n);
386 buffer_put_bignum(&buffer, challenge);
387 buffer_append(&buffer, session_id, 16);
388 buffer_put_int(&buffer, response_type);
390 if (ssh_request_reply(auth, &buffer, &buffer) == 0) {
391 buffer_free(&buffer);
394 type = buffer_get_char(&buffer);
396 if (agent_failed(type)) {
397 logit("Agent admitted failure to authenticate using the key.");
398 } else if (type != SSH_AGENT_RSA_RESPONSE) {
399 fatal("Bad authentication response: %d", type);
403 * Get the response from the packet. This will abort with a
404 * fatal error if the packet is corrupt.
406 for (i = 0; i < 16; i++)
407 response[i] = (u_char)buffer_get_char(&buffer);
409 buffer_free(&buffer);
413 /* ask agent to sign data, returns -1 on error, 0 on success */
415 ssh_agent_sign(AuthenticationConnection *auth,
417 u_char **sigp, u_int *lenp,
418 u_char *data, u_int datalen)
420 extern int datafellows;
427 if (key_to_blob(key, &blob, &blen) == 0)
430 if (datafellows & SSH_BUG_SIGBLOB)
431 flags = SSH_AGENT_OLD_SIGNATURE;
434 buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
435 buffer_put_string(&msg, blob, blen);
436 buffer_put_string(&msg, data, datalen);
437 buffer_put_int(&msg, flags);
440 if (ssh_request_reply(auth, &msg, &msg) == 0) {
444 type = buffer_get_char(&msg);
445 if (agent_failed(type)) {
446 logit("Agent admitted failure to sign using the key.");
447 } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
448 fatal("Bad authentication response: %d", type);
451 *sigp = buffer_get_string(&msg, lenp);
457 /* Encode key for a message to the agent. */
460 ssh_encode_identity_rsa1(Buffer *b, RSA *key, const char *comment)
462 buffer_put_int(b, BN_num_bits(key->n));
463 buffer_put_bignum(b, key->n);
464 buffer_put_bignum(b, key->e);
465 buffer_put_bignum(b, key->d);
466 /* To keep within the protocol: p < q for ssh. in SSL p > q */
467 buffer_put_bignum(b, key->iqmp); /* ssh key->u */
468 buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
469 buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
470 buffer_put_cstring(b, comment);
474 ssh_encode_identity_ssh2(Buffer *b, Key *key, const char *comment)
476 buffer_put_cstring(b, key_ssh_name(key));
479 buffer_put_bignum2(b, key->rsa->n);
480 buffer_put_bignum2(b, key->rsa->e);
481 buffer_put_bignum2(b, key->rsa->d);
482 buffer_put_bignum2(b, key->rsa->iqmp);
483 buffer_put_bignum2(b, key->rsa->p);
484 buffer_put_bignum2(b, key->rsa->q);
487 buffer_put_bignum2(b, key->dsa->p);
488 buffer_put_bignum2(b, key->dsa->q);
489 buffer_put_bignum2(b, key->dsa->g);
490 buffer_put_bignum2(b, key->dsa->pub_key);
491 buffer_put_bignum2(b, key->dsa->priv_key);
494 buffer_put_cstring(b, comment);
498 * Adds an identity to the authentication server. This call is not meant to
499 * be used by normal applications.
503 ssh_add_identity_constrained(AuthenticationConnection *auth, Key *key,
504 const char *comment, u_int life, u_int confirm)
507 int type, constrained = (life || confirm);
514 SSH_AGENTC_ADD_RSA_ID_CONSTRAINED :
515 SSH_AGENTC_ADD_RSA_IDENTITY;
516 buffer_put_char(&msg, type);
517 ssh_encode_identity_rsa1(&msg, key->rsa, comment);
522 SSH2_AGENTC_ADD_ID_CONSTRAINED :
523 SSH2_AGENTC_ADD_IDENTITY;
524 buffer_put_char(&msg, type);
525 ssh_encode_identity_ssh2(&msg, key, comment);
533 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
534 buffer_put_int(&msg, life);
537 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM);
539 if (ssh_request_reply(auth, &msg, &msg) == 0) {
543 type = buffer_get_char(&msg);
545 return decode_reply(type);
549 ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
551 return ssh_add_identity_constrained(auth, key, comment, 0, 0);
555 * Removes an identity from the authentication server. This call is not
556 * meant to be used by normal applications.
560 ssh_remove_identity(AuthenticationConnection *auth, Key *key)
569 if (key->type == KEY_RSA1) {
570 buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
571 buffer_put_int(&msg, BN_num_bits(key->rsa->n));
572 buffer_put_bignum(&msg, key->rsa->e);
573 buffer_put_bignum(&msg, key->rsa->n);
574 } else if (key->type == KEY_DSA || key->type == KEY_RSA) {
575 key_to_blob(key, &blob, &blen);
576 buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
577 buffer_put_string(&msg, blob, blen);
583 if (ssh_request_reply(auth, &msg, &msg) == 0) {
587 type = buffer_get_char(&msg);
589 return decode_reply(type);
593 ssh_update_card(AuthenticationConnection *auth, int add,
594 const char *reader_id, const char *pin, u_int life, u_int confirm)
597 int type, constrained = (life || confirm);
601 SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED :
602 SSH_AGENTC_ADD_SMARTCARD_KEY;
604 type = SSH_AGENTC_REMOVE_SMARTCARD_KEY;
607 buffer_put_char(&msg, type);
608 buffer_put_cstring(&msg, reader_id);
609 buffer_put_cstring(&msg, pin);
613 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
614 buffer_put_int(&msg, life);
617 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM);
620 if (ssh_request_reply(auth, &msg, &msg) == 0) {
624 type = buffer_get_char(&msg);
626 return decode_reply(type);
630 * Removes all identities from the agent. This call is not meant to be used
631 * by normal applications.
635 ssh_remove_all_identities(AuthenticationConnection *auth, int version)
639 int code = (version==1) ?
640 SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
641 SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
644 buffer_put_char(&msg, code);
646 if (ssh_request_reply(auth, &msg, &msg) == 0) {
650 type = buffer_get_char(&msg);
652 return decode_reply(type);
656 decode_reply(int type)
659 case SSH_AGENT_FAILURE:
660 case SSH_COM_AGENT2_FAILURE:
661 case SSH2_AGENT_FAILURE:
662 logit("SSH_AGENT_FAILURE");
664 case SSH_AGENT_SUCCESS:
667 fatal("Bad response from authentication agent: %d", type);