1 /* $OpenBSD: authfd.c,v 1.77 2006/07/17 01:31:09 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>
63 static int agent_present = 0;
66 int decode_reply(int type);
68 /* macro to check for "agent failure" message */
69 #define agent_failed(x) \
70 ((x == SSH_AGENT_FAILURE) || (x == SSH_COM_AGENT2_FAILURE) || \
71 (x == SSH2_AGENT_FAILURE))
74 ssh_agent_present(void)
80 if ((authfd = ssh_get_authentication_socket()) == -1)
83 ssh_close_authentication_socket(authfd);
88 /* Returns the number of the authentication fd, or -1 if there is none. */
91 ssh_get_authentication_socket(void)
93 const char *authsocket;
95 struct sockaddr_un sunaddr;
97 authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
101 sunaddr.sun_family = AF_UNIX;
102 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
104 sock = socket(AF_UNIX, SOCK_STREAM, 0);
109 if (fcntl(sock, F_SETFD, 1) == -1) {
113 if (connect(sock, (struct sockaddr *)&sunaddr, sizeof sunaddr) < 0) {
122 ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply)
127 /* Get the length of the message, and format it in the buffer. */
128 len = buffer_len(request);
131 /* Send the length and then the packet to the agent. */
132 if (atomicio(vwrite, auth->fd, buf, 4) != 4 ||
133 atomicio(vwrite, auth->fd, buffer_ptr(request),
134 buffer_len(request)) != buffer_len(request)) {
135 error("Error writing to authentication socket.");
139 * Wait for response from the agent. First read the length of the
142 if (atomicio(read, auth->fd, buf, 4) != 4) {
143 error("Error reading response length from authentication socket.");
147 /* Extract the length, and check it for sanity. */
149 if (len > 256 * 1024)
150 fatal("Authentication response too long: %u", len);
152 /* Read the rest of the response in to the buffer. */
158 if (atomicio(read, auth->fd, buf, l) != l) {
159 error("Error reading response from authentication socket.");
162 buffer_append(reply, buf, l);
169 * Closes the agent socket if it should be closed (depends on how it was
170 * obtained). The argument must have been returned by
171 * ssh_get_authentication_socket().
175 ssh_close_authentication_socket(int sock)
177 if (getenv(SSH_AUTHSOCKET_ENV_NAME))
182 * Opens and connects a private socket for communication with the
183 * authentication agent. Returns the file descriptor (which must be
184 * shut down and closed by the caller when no longer needed).
185 * Returns NULL if an error occurred and the connection could not be
189 AuthenticationConnection *
190 ssh_get_authentication_connection(void)
192 AuthenticationConnection *auth;
195 sock = ssh_get_authentication_socket();
198 * Fail if we couldn't obtain a connection. This happens if we
199 * exited due to a timeout.
204 auth = xmalloc(sizeof(*auth));
206 buffer_init(&auth->identities);
213 * Closes the connection to the authentication agent and frees any associated
218 ssh_close_authentication_connection(AuthenticationConnection *auth)
220 buffer_free(&auth->identities);
225 /* Lock/unlock agent */
227 ssh_lock_agent(AuthenticationConnection *auth, int lock, const char *password)
233 buffer_put_char(&msg, lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK);
234 buffer_put_cstring(&msg, password);
236 if (ssh_request_reply(auth, &msg, &msg) == 0) {
240 type = buffer_get_char(&msg);
242 return decode_reply(type);
246 * Returns the first authentication identity held by the agent.
250 ssh_get_num_identities(AuthenticationConnection *auth, int version)
252 int type, code1 = 0, code2 = 0;
257 code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
258 code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
261 code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
262 code2 = SSH2_AGENT_IDENTITIES_ANSWER;
269 * Send a message to the agent requesting for a list of the
270 * identities it can represent.
272 buffer_init(&request);
273 buffer_put_char(&request, code1);
275 buffer_clear(&auth->identities);
276 if (ssh_request_reply(auth, &request, &auth->identities) == 0) {
277 buffer_free(&request);
280 buffer_free(&request);
282 /* Get message type, and verify that we got a proper answer. */
283 type = buffer_get_char(&auth->identities);
284 if (agent_failed(type)) {
286 } else if (type != code2) {
287 fatal("Bad authentication reply message type: %d", type);
290 /* Get the number of entries in the response and check it for sanity. */
291 auth->howmany = buffer_get_int(&auth->identities);
292 if ((u_int)auth->howmany > 1024)
293 fatal("Too many identities in authentication reply: %d",
296 return auth->howmany;
300 ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version)
302 /* get number of identities and return the first entry (if any). */
303 if (ssh_get_num_identities(auth, version) > 0)
304 return ssh_get_next_identity(auth, comment, version);
309 ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version)
317 /* Return failure if no more entries. */
318 if (auth->howmany <= 0)
322 * Get the next entry from the packet. These will abort with a fatal
323 * error if the packet is too short or contains corrupt data.
327 key = key_new(KEY_RSA1);
328 bits = buffer_get_int(&auth->identities);
329 buffer_get_bignum(&auth->identities, key->rsa->e);
330 buffer_get_bignum(&auth->identities, key->rsa->n);
331 *comment = buffer_get_string(&auth->identities, NULL);
332 keybits = BN_num_bits(key->rsa->n);
333 if (keybits < 0 || bits != (u_int)keybits)
334 logit("Warning: identity keysize mismatch: actual %d, announced %u",
335 BN_num_bits(key->rsa->n), bits);
338 blob = buffer_get_string(&auth->identities, &blen);
339 *comment = buffer_get_string(&auth->identities, NULL);
340 key = key_from_blob(blob, blen);
346 /* Decrement the number of remaining entries. */
352 * Generates a random challenge, sends it to the agent, and waits for
353 * response from the agent. Returns true (non-zero) if the agent gave the
354 * correct answer, zero otherwise. Response type selects the style of
355 * response desired, with 0 corresponding to protocol version 1.0 (no longer
356 * supported) and 1 corresponding to protocol version 1.1.
360 ssh_decrypt_challenge(AuthenticationConnection *auth,
361 Key* key, BIGNUM *challenge,
362 u_char session_id[16],
371 if (key->type != KEY_RSA1)
373 if (response_type == 0) {
374 logit("Compatibility with ssh protocol version 1.0 no longer supported.");
377 buffer_init(&buffer);
378 buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE);
379 buffer_put_int(&buffer, BN_num_bits(key->rsa->n));
380 buffer_put_bignum(&buffer, key->rsa->e);
381 buffer_put_bignum(&buffer, key->rsa->n);
382 buffer_put_bignum(&buffer, challenge);
383 buffer_append(&buffer, session_id, 16);
384 buffer_put_int(&buffer, response_type);
386 if (ssh_request_reply(auth, &buffer, &buffer) == 0) {
387 buffer_free(&buffer);
390 type = buffer_get_char(&buffer);
392 if (agent_failed(type)) {
393 logit("Agent admitted failure to authenticate using the key.");
394 } else if (type != SSH_AGENT_RSA_RESPONSE) {
395 fatal("Bad authentication response: %d", type);
399 * Get the response from the packet. This will abort with a
400 * fatal error if the packet is corrupt.
402 for (i = 0; i < 16; i++)
403 response[i] = (u_char)buffer_get_char(&buffer);
405 buffer_free(&buffer);
409 /* ask agent to sign data, returns -1 on error, 0 on success */
411 ssh_agent_sign(AuthenticationConnection *auth,
413 u_char **sigp, u_int *lenp,
414 u_char *data, u_int datalen)
416 extern int datafellows;
423 if (key_to_blob(key, &blob, &blen) == 0)
426 if (datafellows & SSH_BUG_SIGBLOB)
427 flags = SSH_AGENT_OLD_SIGNATURE;
430 buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
431 buffer_put_string(&msg, blob, blen);
432 buffer_put_string(&msg, data, datalen);
433 buffer_put_int(&msg, flags);
436 if (ssh_request_reply(auth, &msg, &msg) == 0) {
440 type = buffer_get_char(&msg);
441 if (agent_failed(type)) {
442 logit("Agent admitted failure to sign using the key.");
443 } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
444 fatal("Bad authentication response: %d", type);
447 *sigp = buffer_get_string(&msg, lenp);
453 /* Encode key for a message to the agent. */
456 ssh_encode_identity_rsa1(Buffer *b, RSA *key, const char *comment)
458 buffer_put_int(b, BN_num_bits(key->n));
459 buffer_put_bignum(b, key->n);
460 buffer_put_bignum(b, key->e);
461 buffer_put_bignum(b, key->d);
462 /* To keep within the protocol: p < q for ssh. in SSL p > q */
463 buffer_put_bignum(b, key->iqmp); /* ssh key->u */
464 buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
465 buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
466 buffer_put_cstring(b, comment);
470 ssh_encode_identity_ssh2(Buffer *b, Key *key, const char *comment)
472 buffer_put_cstring(b, key_ssh_name(key));
475 buffer_put_bignum2(b, key->rsa->n);
476 buffer_put_bignum2(b, key->rsa->e);
477 buffer_put_bignum2(b, key->rsa->d);
478 buffer_put_bignum2(b, key->rsa->iqmp);
479 buffer_put_bignum2(b, key->rsa->p);
480 buffer_put_bignum2(b, key->rsa->q);
483 buffer_put_bignum2(b, key->dsa->p);
484 buffer_put_bignum2(b, key->dsa->q);
485 buffer_put_bignum2(b, key->dsa->g);
486 buffer_put_bignum2(b, key->dsa->pub_key);
487 buffer_put_bignum2(b, key->dsa->priv_key);
490 buffer_put_cstring(b, comment);
494 * Adds an identity to the authentication server. This call is not meant to
495 * be used by normal applications.
499 ssh_add_identity_constrained(AuthenticationConnection *auth, Key *key,
500 const char *comment, u_int life, u_int confirm)
503 int type, constrained = (life || confirm);
510 SSH_AGENTC_ADD_RSA_ID_CONSTRAINED :
511 SSH_AGENTC_ADD_RSA_IDENTITY;
512 buffer_put_char(&msg, type);
513 ssh_encode_identity_rsa1(&msg, key->rsa, comment);
518 SSH2_AGENTC_ADD_ID_CONSTRAINED :
519 SSH2_AGENTC_ADD_IDENTITY;
520 buffer_put_char(&msg, type);
521 ssh_encode_identity_ssh2(&msg, key, comment);
529 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
530 buffer_put_int(&msg, life);
533 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM);
535 if (ssh_request_reply(auth, &msg, &msg) == 0) {
539 type = buffer_get_char(&msg);
541 return decode_reply(type);
545 ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
547 return ssh_add_identity_constrained(auth, key, comment, 0, 0);
551 * Removes an identity from the authentication server. This call is not
552 * meant to be used by normal applications.
556 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);
570 } else if (key->type == KEY_DSA || key->type == KEY_RSA) {
571 key_to_blob(key, &blob, &blen);
572 buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
573 buffer_put_string(&msg, blob, blen);
579 if (ssh_request_reply(auth, &msg, &msg) == 0) {
583 type = buffer_get_char(&msg);
585 return decode_reply(type);
589 ssh_update_card(AuthenticationConnection *auth, int add,
590 const char *reader_id, const char *pin, u_int life, u_int confirm)
593 int type, constrained = (life || confirm);
597 SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED :
598 SSH_AGENTC_ADD_SMARTCARD_KEY;
600 type = SSH_AGENTC_REMOVE_SMARTCARD_KEY;
603 buffer_put_char(&msg, type);
604 buffer_put_cstring(&msg, reader_id);
605 buffer_put_cstring(&msg, pin);
609 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
610 buffer_put_int(&msg, life);
613 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM);
616 if (ssh_request_reply(auth, &msg, &msg) == 0) {
620 type = buffer_get_char(&msg);
622 return decode_reply(type);
626 * Removes all identities from the agent. This call is not meant to be used
627 * by normal applications.
631 ssh_remove_all_identities(AuthenticationConnection *auth, int version)
635 int code = (version==1) ?
636 SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
637 SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
640 buffer_put_char(&msg, code);
642 if (ssh_request_reply(auth, &msg, &msg) == 0) {
646 type = buffer_get_char(&msg);
648 return decode_reply(type);
652 decode_reply(int type)
655 case SSH_AGENT_FAILURE:
656 case SSH_COM_AGENT2_FAILURE:
657 case SSH2_AGENT_FAILURE:
658 logit("SSH_AGENT_FAILURE");
660 case SSH_AGENT_SUCCESS:
663 fatal("Bad response from authentication agent: %d", type);