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 1.56 2002/06/25 16:22:42 markus Exp $");
40 #include <openssl/evp.h>
57 int decode_reply(int type);
59 /* macro to check for "agent failure" message */
60 #define agent_failed(x) \
61 ((x == SSH_AGENT_FAILURE) || (x == SSH_COM_AGENT2_FAILURE) || \
62 (x == SSH2_AGENT_FAILURE))
64 /* Returns the number of the authentication fd, or -1 if there is none. */
67 ssh_get_authentication_socket(void)
69 const char *authsocket;
71 struct sockaddr_un sunaddr;
73 authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
77 sunaddr.sun_family = AF_UNIX;
78 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
80 sock = socket(AF_UNIX, SOCK_STREAM, 0);
85 if (fcntl(sock, F_SETFD, 1) == -1) {
89 if (connect(sock, (struct sockaddr *) &sunaddr, sizeof sunaddr) < 0) {
97 ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply)
102 /* Get the length of the message, and format it in the buffer. */
103 len = buffer_len(request);
106 /* Send the length and then the packet to the agent. */
107 if (atomicio(write, auth->fd, buf, 4) != 4 ||
108 atomicio(write, auth->fd, buffer_ptr(request),
109 buffer_len(request)) != buffer_len(request)) {
110 error("Error writing to authentication socket.");
114 * Wait for response from the agent. First read the length of the
119 l = read(auth->fd, buf + 4 - len, len);
120 if (l == -1 && (errno == EAGAIN || errno == EINTR))
123 error("Error reading response length from authentication socket.");
129 /* Extract the length, and check it for sanity. */
130 len = GET_32BIT(buf);
131 if (len > 256 * 1024)
132 fatal("Authentication response too long: %d", len);
134 /* Read the rest of the response in to the buffer. */
140 l = read(auth->fd, buf, l);
141 if (l == -1 && (errno == EAGAIN || errno == EINTR))
144 error("Error reading response from authentication socket.");
147 buffer_append(reply, buf, l);
154 * Closes the agent socket if it should be closed (depends on how it was
155 * obtained). The argument must have been returned by
156 * ssh_get_authentication_socket().
160 ssh_close_authentication_socket(int sock)
162 if (getenv(SSH_AUTHSOCKET_ENV_NAME))
167 * Opens and connects a private socket for communication with the
168 * authentication agent. Returns the file descriptor (which must be
169 * shut down and closed by the caller when no longer needed).
170 * Returns NULL if an error occurred and the connection could not be
174 AuthenticationConnection *
175 ssh_get_authentication_connection(void)
177 AuthenticationConnection *auth;
180 sock = ssh_get_authentication_socket();
183 * Fail if we couldn't obtain a connection. This happens if we
184 * exited due to a timeout.
189 auth = xmalloc(sizeof(*auth));
191 buffer_init(&auth->identities);
198 * Closes the connection to the authentication agent and frees any associated
203 ssh_close_authentication_connection(AuthenticationConnection *auth)
205 buffer_free(&auth->identities);
210 /* Lock/unlock agent */
212 ssh_lock_agent(AuthenticationConnection *auth, int lock, const char *password)
218 buffer_put_char(&msg, lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK);
219 buffer_put_cstring(&msg, password);
221 if (ssh_request_reply(auth, &msg, &msg) == 0) {
225 type = buffer_get_char(&msg);
227 return decode_reply(type);
231 * Returns the first authentication identity held by the agent.
235 ssh_get_num_identities(AuthenticationConnection *auth, int version)
237 int type, code1 = 0, code2 = 0;
242 code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
243 code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
246 code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
247 code2 = SSH2_AGENT_IDENTITIES_ANSWER;
254 * Send a message to the agent requesting for a list of the
255 * identities it can represent.
257 buffer_init(&request);
258 buffer_put_char(&request, code1);
260 buffer_clear(&auth->identities);
261 if (ssh_request_reply(auth, &request, &auth->identities) == 0) {
262 buffer_free(&request);
265 buffer_free(&request);
267 /* Get message type, and verify that we got a proper answer. */
268 type = buffer_get_char(&auth->identities);
269 if (agent_failed(type)) {
271 } else if (type != code2) {
272 fatal("Bad authentication reply message type: %d", type);
275 /* Get the number of entries in the response and check it for sanity. */
276 auth->howmany = buffer_get_int(&auth->identities);
277 if (auth->howmany > 1024)
278 fatal("Too many identities in authentication reply: %d",
281 return auth->howmany;
285 ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version)
287 /* get number of identities and return the first entry (if any). */
288 if (ssh_get_num_identities(auth, version) > 0)
289 return ssh_get_next_identity(auth, comment, version);
294 ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version)
301 /* Return failure if no more entries. */
302 if (auth->howmany <= 0)
306 * Get the next entry from the packet. These will abort with a fatal
307 * error if the packet is too short or contains corrupt data.
311 key = key_new(KEY_RSA1);
312 bits = buffer_get_int(&auth->identities);
313 buffer_get_bignum(&auth->identities, key->rsa->e);
314 buffer_get_bignum(&auth->identities, key->rsa->n);
315 *comment = buffer_get_string(&auth->identities, NULL);
316 if (bits != BN_num_bits(key->rsa->n))
317 log("Warning: identity keysize mismatch: actual %d, announced %u",
318 BN_num_bits(key->rsa->n), bits);
321 blob = buffer_get_string(&auth->identities, &blen);
322 *comment = buffer_get_string(&auth->identities, NULL);
323 key = key_from_blob(blob, blen);
330 /* Decrement the number of remaining entries. */
336 * Generates a random challenge, sends it to the agent, and waits for
337 * response from the agent. Returns true (non-zero) if the agent gave the
338 * correct answer, zero otherwise. Response type selects the style of
339 * response desired, with 0 corresponding to protocol version 1.0 (no longer
340 * supported) and 1 corresponding to protocol version 1.1.
344 ssh_decrypt_challenge(AuthenticationConnection *auth,
345 Key* key, BIGNUM *challenge,
346 u_char session_id[16],
355 if (key->type != KEY_RSA1)
357 if (response_type == 0) {
358 log("Compatibility with ssh protocol version 1.0 no longer supported.");
361 buffer_init(&buffer);
362 buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE);
363 buffer_put_int(&buffer, BN_num_bits(key->rsa->n));
364 buffer_put_bignum(&buffer, key->rsa->e);
365 buffer_put_bignum(&buffer, key->rsa->n);
366 buffer_put_bignum(&buffer, challenge);
367 buffer_append(&buffer, session_id, 16);
368 buffer_put_int(&buffer, response_type);
370 if (ssh_request_reply(auth, &buffer, &buffer) == 0) {
371 buffer_free(&buffer);
374 type = buffer_get_char(&buffer);
376 if (agent_failed(type)) {
377 log("Agent admitted failure to authenticate using the key.");
378 } else if (type != SSH_AGENT_RSA_RESPONSE) {
379 fatal("Bad authentication response: %d", type);
383 * Get the response from the packet. This will abort with a
384 * fatal error if the packet is corrupt.
386 for (i = 0; i < 16; i++)
387 response[i] = buffer_get_char(&buffer);
389 buffer_free(&buffer);
393 /* ask agent to sign data, returns -1 on error, 0 on success */
395 ssh_agent_sign(AuthenticationConnection *auth,
397 u_char **sigp, u_int *lenp,
398 u_char *data, u_int datalen)
400 extern int datafellows;
407 if (key_to_blob(key, &blob, &blen) == 0)
410 if (datafellows & SSH_BUG_SIGBLOB)
411 flags = SSH_AGENT_OLD_SIGNATURE;
414 buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
415 buffer_put_string(&msg, blob, blen);
416 buffer_put_string(&msg, data, datalen);
417 buffer_put_int(&msg, flags);
420 if (ssh_request_reply(auth, &msg, &msg) == 0) {
424 type = buffer_get_char(&msg);
425 if (agent_failed(type)) {
426 log("Agent admitted failure to sign using the key.");
427 } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
428 fatal("Bad authentication response: %d", type);
431 *sigp = buffer_get_string(&msg, lenp);
437 /* Encode key for a message to the agent. */
440 ssh_encode_identity_rsa1(Buffer *b, RSA *key, const char *comment)
442 buffer_put_int(b, BN_num_bits(key->n));
443 buffer_put_bignum(b, key->n);
444 buffer_put_bignum(b, key->e);
445 buffer_put_bignum(b, key->d);
446 /* To keep within the protocol: p < q for ssh. in SSL p > q */
447 buffer_put_bignum(b, key->iqmp); /* ssh key->u */
448 buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
449 buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
450 buffer_put_cstring(b, comment);
454 ssh_encode_identity_ssh2(Buffer *b, Key *key, const char *comment)
456 buffer_put_cstring(b, key_ssh_name(key));
459 buffer_put_bignum2(b, key->rsa->n);
460 buffer_put_bignum2(b, key->rsa->e);
461 buffer_put_bignum2(b, key->rsa->d);
462 buffer_put_bignum2(b, key->rsa->iqmp);
463 buffer_put_bignum2(b, key->rsa->p);
464 buffer_put_bignum2(b, key->rsa->q);
467 buffer_put_bignum2(b, key->dsa->p);
468 buffer_put_bignum2(b, key->dsa->q);
469 buffer_put_bignum2(b, key->dsa->g);
470 buffer_put_bignum2(b, key->dsa->pub_key);
471 buffer_put_bignum2(b, key->dsa->priv_key);
474 buffer_put_cstring(b, comment);
478 * Adds an identity to the authentication server. This call is not meant to
479 * be used by normal applications.
483 ssh_add_identity_constrained(AuthenticationConnection *auth, Key *key,
484 const char *comment, u_int life)
487 int type, constrained = (life != 0);
494 SSH_AGENTC_ADD_RSA_ID_CONSTRAINED :
495 SSH_AGENTC_ADD_RSA_IDENTITY;
496 buffer_put_char(&msg, type);
497 ssh_encode_identity_rsa1(&msg, key->rsa, comment);
502 SSH2_AGENTC_ADD_ID_CONSTRAINED :
503 SSH2_AGENTC_ADD_IDENTITY;
504 buffer_put_char(&msg, type);
505 ssh_encode_identity_ssh2(&msg, key, comment);
514 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
515 buffer_put_int(&msg, life);
518 if (ssh_request_reply(auth, &msg, &msg) == 0) {
522 type = buffer_get_char(&msg);
524 return decode_reply(type);
528 ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
530 return ssh_add_identity_constrained(auth, key, comment, 0);
534 * Removes an identity from the authentication server. This call is not
535 * meant to be used by normal applications.
539 ssh_remove_identity(AuthenticationConnection *auth, Key *key)
548 if (key->type == KEY_RSA1) {
549 buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
550 buffer_put_int(&msg, BN_num_bits(key->rsa->n));
551 buffer_put_bignum(&msg, key->rsa->e);
552 buffer_put_bignum(&msg, key->rsa->n);
553 } else if (key->type == KEY_DSA || key->type == KEY_RSA) {
554 key_to_blob(key, &blob, &blen);
555 buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
556 buffer_put_string(&msg, blob, blen);
562 if (ssh_request_reply(auth, &msg, &msg) == 0) {
566 type = buffer_get_char(&msg);
568 return decode_reply(type);
572 ssh_update_card(AuthenticationConnection *auth, int add, const char *reader_id, const char *pin)
578 buffer_put_char(&msg, add ? SSH_AGENTC_ADD_SMARTCARD_KEY :
579 SSH_AGENTC_REMOVE_SMARTCARD_KEY);
580 buffer_put_cstring(&msg, reader_id);
581 buffer_put_cstring(&msg, pin);
582 if (ssh_request_reply(auth, &msg, &msg) == 0) {
586 type = buffer_get_char(&msg);
588 return decode_reply(type);
592 * Removes all identities from the agent. This call is not meant to be used
593 * by normal applications.
597 ssh_remove_all_identities(AuthenticationConnection *auth, int version)
601 int code = (version==1) ?
602 SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
603 SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
606 buffer_put_char(&msg, code);
608 if (ssh_request_reply(auth, &msg, &msg) == 0) {
612 type = buffer_get_char(&msg);
614 return decode_reply(type);
618 decode_reply(int type)
621 case SSH_AGENT_FAILURE:
622 case SSH_COM_AGENT2_FAILURE:
623 case SSH2_AGENT_FAILURE:
624 log("SSH_AGENT_FAILURE");
626 case SSH_AGENT_SUCCESS:
629 fatal("Bad response from authentication agent: %d", type);