1 /* $OpenBSD: authfd.c,v 1.75 2006/07/08 21:47:12 stevesk 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>
60 static int agent_present = 0;
63 int decode_reply(int type);
65 /* macro to check for "agent failure" message */
66 #define agent_failed(x) \
67 ((x == SSH_AGENT_FAILURE) || (x == SSH_COM_AGENT2_FAILURE) || \
68 (x == SSH2_AGENT_FAILURE))
71 ssh_agent_present(void)
77 if ((authfd = ssh_get_authentication_socket()) == -1)
80 ssh_close_authentication_socket(authfd);
85 /* Returns the number of the authentication fd, or -1 if there is none. */
88 ssh_get_authentication_socket(void)
90 const char *authsocket;
92 struct sockaddr_un sunaddr;
94 authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
98 sunaddr.sun_family = AF_UNIX;
99 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
101 sock = socket(AF_UNIX, SOCK_STREAM, 0);
106 if (fcntl(sock, F_SETFD, 1) == -1) {
110 if (connect(sock, (struct sockaddr *)&sunaddr, sizeof sunaddr) < 0) {
119 ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply)
124 /* Get the length of the message, and format it in the buffer. */
125 len = buffer_len(request);
128 /* Send the length and then the packet to the agent. */
129 if (atomicio(vwrite, auth->fd, buf, 4) != 4 ||
130 atomicio(vwrite, auth->fd, buffer_ptr(request),
131 buffer_len(request)) != buffer_len(request)) {
132 error("Error writing to authentication socket.");
136 * Wait for response from the agent. First read the length of the
139 if (atomicio(read, auth->fd, buf, 4) != 4) {
140 error("Error reading response length from authentication socket.");
144 /* Extract the length, and check it for sanity. */
146 if (len > 256 * 1024)
147 fatal("Authentication response too long: %u", len);
149 /* Read the rest of the response in to the buffer. */
155 if (atomicio(read, auth->fd, buf, l) != l) {
156 error("Error reading response from authentication socket.");
159 buffer_append(reply, buf, l);
166 * Closes the agent socket if it should be closed (depends on how it was
167 * obtained). The argument must have been returned by
168 * ssh_get_authentication_socket().
172 ssh_close_authentication_socket(int sock)
174 if (getenv(SSH_AUTHSOCKET_ENV_NAME))
179 * Opens and connects a private socket for communication with the
180 * authentication agent. Returns the file descriptor (which must be
181 * shut down and closed by the caller when no longer needed).
182 * Returns NULL if an error occurred and the connection could not be
186 AuthenticationConnection *
187 ssh_get_authentication_connection(void)
189 AuthenticationConnection *auth;
192 sock = ssh_get_authentication_socket();
195 * Fail if we couldn't obtain a connection. This happens if we
196 * exited due to a timeout.
201 auth = xmalloc(sizeof(*auth));
203 buffer_init(&auth->identities);
210 * Closes the connection to the authentication agent and frees any associated
215 ssh_close_authentication_connection(AuthenticationConnection *auth)
217 buffer_free(&auth->identities);
222 /* Lock/unlock agent */
224 ssh_lock_agent(AuthenticationConnection *auth, int lock, const char *password)
230 buffer_put_char(&msg, lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK);
231 buffer_put_cstring(&msg, password);
233 if (ssh_request_reply(auth, &msg, &msg) == 0) {
237 type = buffer_get_char(&msg);
239 return decode_reply(type);
243 * Returns the first authentication identity held by the agent.
247 ssh_get_num_identities(AuthenticationConnection *auth, int version)
249 int type, code1 = 0, code2 = 0;
254 code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
255 code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
258 code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
259 code2 = SSH2_AGENT_IDENTITIES_ANSWER;
266 * Send a message to the agent requesting for a list of the
267 * identities it can represent.
269 buffer_init(&request);
270 buffer_put_char(&request, code1);
272 buffer_clear(&auth->identities);
273 if (ssh_request_reply(auth, &request, &auth->identities) == 0) {
274 buffer_free(&request);
277 buffer_free(&request);
279 /* Get message type, and verify that we got a proper answer. */
280 type = buffer_get_char(&auth->identities);
281 if (agent_failed(type)) {
283 } else if (type != code2) {
284 fatal("Bad authentication reply message type: %d", type);
287 /* Get the number of entries in the response and check it for sanity. */
288 auth->howmany = buffer_get_int(&auth->identities);
289 if ((u_int)auth->howmany > 1024)
290 fatal("Too many identities in authentication reply: %d",
293 return auth->howmany;
297 ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version)
299 /* get number of identities and return the first entry (if any). */
300 if (ssh_get_num_identities(auth, version) > 0)
301 return ssh_get_next_identity(auth, comment, version);
306 ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version)
314 /* Return failure if no more entries. */
315 if (auth->howmany <= 0)
319 * Get the next entry from the packet. These will abort with a fatal
320 * error if the packet is too short or contains corrupt data.
324 key = key_new(KEY_RSA1);
325 bits = buffer_get_int(&auth->identities);
326 buffer_get_bignum(&auth->identities, key->rsa->e);
327 buffer_get_bignum(&auth->identities, key->rsa->n);
328 *comment = buffer_get_string(&auth->identities, NULL);
329 keybits = BN_num_bits(key->rsa->n);
330 if (keybits < 0 || bits != (u_int)keybits)
331 logit("Warning: identity keysize mismatch: actual %d, announced %u",
332 BN_num_bits(key->rsa->n), bits);
335 blob = buffer_get_string(&auth->identities, &blen);
336 *comment = buffer_get_string(&auth->identities, NULL);
337 key = key_from_blob(blob, blen);
343 /* Decrement the number of remaining entries. */
349 * Generates a random challenge, sends it to the agent, and waits for
350 * response from the agent. Returns true (non-zero) if the agent gave the
351 * correct answer, zero otherwise. Response type selects the style of
352 * response desired, with 0 corresponding to protocol version 1.0 (no longer
353 * supported) and 1 corresponding to protocol version 1.1.
357 ssh_decrypt_challenge(AuthenticationConnection *auth,
358 Key* key, BIGNUM *challenge,
359 u_char session_id[16],
368 if (key->type != KEY_RSA1)
370 if (response_type == 0) {
371 logit("Compatibility with ssh protocol version 1.0 no longer supported.");
374 buffer_init(&buffer);
375 buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE);
376 buffer_put_int(&buffer, BN_num_bits(key->rsa->n));
377 buffer_put_bignum(&buffer, key->rsa->e);
378 buffer_put_bignum(&buffer, key->rsa->n);
379 buffer_put_bignum(&buffer, challenge);
380 buffer_append(&buffer, session_id, 16);
381 buffer_put_int(&buffer, response_type);
383 if (ssh_request_reply(auth, &buffer, &buffer) == 0) {
384 buffer_free(&buffer);
387 type = buffer_get_char(&buffer);
389 if (agent_failed(type)) {
390 logit("Agent admitted failure to authenticate using the key.");
391 } else if (type != SSH_AGENT_RSA_RESPONSE) {
392 fatal("Bad authentication response: %d", type);
396 * Get the response from the packet. This will abort with a
397 * fatal error if the packet is corrupt.
399 for (i = 0; i < 16; i++)
400 response[i] = (u_char)buffer_get_char(&buffer);
402 buffer_free(&buffer);
406 /* ask agent to sign data, returns -1 on error, 0 on success */
408 ssh_agent_sign(AuthenticationConnection *auth,
410 u_char **sigp, u_int *lenp,
411 u_char *data, u_int datalen)
413 extern int datafellows;
420 if (key_to_blob(key, &blob, &blen) == 0)
423 if (datafellows & SSH_BUG_SIGBLOB)
424 flags = SSH_AGENT_OLD_SIGNATURE;
427 buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
428 buffer_put_string(&msg, blob, blen);
429 buffer_put_string(&msg, data, datalen);
430 buffer_put_int(&msg, flags);
433 if (ssh_request_reply(auth, &msg, &msg) == 0) {
437 type = buffer_get_char(&msg);
438 if (agent_failed(type)) {
439 logit("Agent admitted failure to sign using the key.");
440 } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
441 fatal("Bad authentication response: %d", type);
444 *sigp = buffer_get_string(&msg, lenp);
450 /* Encode key for a message to the agent. */
453 ssh_encode_identity_rsa1(Buffer *b, RSA *key, const char *comment)
455 buffer_put_int(b, BN_num_bits(key->n));
456 buffer_put_bignum(b, key->n);
457 buffer_put_bignum(b, key->e);
458 buffer_put_bignum(b, key->d);
459 /* To keep within the protocol: p < q for ssh. in SSL p > q */
460 buffer_put_bignum(b, key->iqmp); /* ssh key->u */
461 buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
462 buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
463 buffer_put_cstring(b, comment);
467 ssh_encode_identity_ssh2(Buffer *b, Key *key, const char *comment)
469 buffer_put_cstring(b, key_ssh_name(key));
472 buffer_put_bignum2(b, key->rsa->n);
473 buffer_put_bignum2(b, key->rsa->e);
474 buffer_put_bignum2(b, key->rsa->d);
475 buffer_put_bignum2(b, key->rsa->iqmp);
476 buffer_put_bignum2(b, key->rsa->p);
477 buffer_put_bignum2(b, key->rsa->q);
480 buffer_put_bignum2(b, key->dsa->p);
481 buffer_put_bignum2(b, key->dsa->q);
482 buffer_put_bignum2(b, key->dsa->g);
483 buffer_put_bignum2(b, key->dsa->pub_key);
484 buffer_put_bignum2(b, key->dsa->priv_key);
487 buffer_put_cstring(b, comment);
491 * Adds an identity to the authentication server. This call is not meant to
492 * be used by normal applications.
496 ssh_add_identity_constrained(AuthenticationConnection *auth, Key *key,
497 const char *comment, u_int life, u_int confirm)
500 int type, constrained = (life || confirm);
507 SSH_AGENTC_ADD_RSA_ID_CONSTRAINED :
508 SSH_AGENTC_ADD_RSA_IDENTITY;
509 buffer_put_char(&msg, type);
510 ssh_encode_identity_rsa1(&msg, key->rsa, comment);
515 SSH2_AGENTC_ADD_ID_CONSTRAINED :
516 SSH2_AGENTC_ADD_IDENTITY;
517 buffer_put_char(&msg, type);
518 ssh_encode_identity_ssh2(&msg, key, comment);
526 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
527 buffer_put_int(&msg, life);
530 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM);
532 if (ssh_request_reply(auth, &msg, &msg) == 0) {
536 type = buffer_get_char(&msg);
538 return decode_reply(type);
542 ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
544 return ssh_add_identity_constrained(auth, key, comment, 0, 0);
548 * Removes an identity from the authentication server. This call is not
549 * meant to be used by normal applications.
553 ssh_remove_identity(AuthenticationConnection *auth, Key *key)
562 if (key->type == KEY_RSA1) {
563 buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
564 buffer_put_int(&msg, BN_num_bits(key->rsa->n));
565 buffer_put_bignum(&msg, key->rsa->e);
566 buffer_put_bignum(&msg, key->rsa->n);
567 } else if (key->type == KEY_DSA || key->type == KEY_RSA) {
568 key_to_blob(key, &blob, &blen);
569 buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
570 buffer_put_string(&msg, blob, blen);
576 if (ssh_request_reply(auth, &msg, &msg) == 0) {
580 type = buffer_get_char(&msg);
582 return decode_reply(type);
586 ssh_update_card(AuthenticationConnection *auth, int add,
587 const char *reader_id, const char *pin, u_int life, u_int confirm)
590 int type, constrained = (life || confirm);
594 SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED :
595 SSH_AGENTC_ADD_SMARTCARD_KEY;
597 type = SSH_AGENTC_REMOVE_SMARTCARD_KEY;
600 buffer_put_char(&msg, type);
601 buffer_put_cstring(&msg, reader_id);
602 buffer_put_cstring(&msg, pin);
606 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
607 buffer_put_int(&msg, life);
610 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM);
613 if (ssh_request_reply(auth, &msg, &msg) == 0) {
617 type = buffer_get_char(&msg);
619 return decode_reply(type);
623 * Removes all identities from the agent. This call is not meant to be used
624 * by normal applications.
628 ssh_remove_all_identities(AuthenticationConnection *auth, int version)
632 int code = (version==1) ?
633 SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
634 SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
637 buffer_put_char(&msg, code);
639 if (ssh_request_reply(auth, &msg, &msg) == 0) {
643 type = buffer_get_char(&msg);
645 return decode_reply(type);
649 decode_reply(int type)
652 case SSH_AGENT_FAILURE:
653 case SSH_COM_AGENT2_FAILURE:
654 case SSH2_AGENT_FAILURE:
655 logit("SSH_AGENT_FAILURE");
657 case SSH_AGENT_SUCCESS:
660 fatal("Bad response from authentication agent: %d", type);