1 /* $OpenBSD: authfd.c,v 1.92 2014/01/31 16:39:19 tedu 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>
45 #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 memset(&sunaddr, 0, sizeof(sunaddr));
106 sunaddr.sun_family = AF_UNIX;
107 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
109 sock = socket(AF_UNIX, SOCK_STREAM, 0);
114 if (fcntl(sock, F_SETFD, FD_CLOEXEC) == -1) {
118 if (connect(sock, (struct sockaddr *)&sunaddr, sizeof sunaddr) < 0) {
127 ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply)
132 /* Get the length of the message, and format it in the buffer. */
133 len = buffer_len(request);
136 /* Send the length and then the packet to the agent. */
137 if (atomicio(vwrite, auth->fd, buf, 4) != 4 ||
138 atomicio(vwrite, auth->fd, buffer_ptr(request),
139 buffer_len(request)) != buffer_len(request)) {
140 error("Error writing to authentication socket.");
144 * Wait for response from the agent. First read the length of the
147 if (atomicio(read, auth->fd, buf, 4) != 4) {
148 error("Error reading response length from authentication socket.");
152 /* Extract the length, and check it for sanity. */
154 if (len > 256 * 1024)
155 fatal("Authentication response too long: %u", len);
157 /* Read the rest of the response in to the buffer. */
163 if (atomicio(read, auth->fd, buf, l) != l) {
164 error("Error reading response from authentication socket.");
167 buffer_append(reply, buf, l);
174 * Closes the agent socket if it should be closed (depends on how it was
175 * obtained). The argument must have been returned by
176 * ssh_get_authentication_socket().
180 ssh_close_authentication_socket(int sock)
182 if (getenv(SSH_AUTHSOCKET_ENV_NAME))
187 * Opens and connects a private socket for communication with the
188 * authentication agent. Returns the file descriptor (which must be
189 * shut down and closed by the caller when no longer needed).
190 * Returns NULL if an error occurred and the connection could not be
194 AuthenticationConnection *
195 ssh_get_authentication_connection(void)
197 AuthenticationConnection *auth;
200 sock = ssh_get_authentication_socket();
203 * Fail if we couldn't obtain a connection. This happens if we
204 * exited due to a timeout.
209 auth = xcalloc(1, sizeof(*auth));
211 buffer_init(&auth->identities);
218 * Closes the connection to the authentication agent and frees any associated
223 ssh_close_authentication_connection(AuthenticationConnection *auth)
225 buffer_free(&auth->identities);
230 /* Lock/unlock agent */
232 ssh_lock_agent(AuthenticationConnection *auth, int lock, const char *password)
238 buffer_put_char(&msg, lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK);
239 buffer_put_cstring(&msg, password);
241 if (ssh_request_reply(auth, &msg, &msg) == 0) {
245 type = buffer_get_char(&msg);
247 return decode_reply(type);
251 * Returns the first authentication identity held by the agent.
255 ssh_get_num_identities(AuthenticationConnection *auth, int version)
257 int type, code1 = 0, code2 = 0;
262 code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
263 code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
266 code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
267 code2 = SSH2_AGENT_IDENTITIES_ANSWER;
274 * Send a message to the agent requesting for a list of the
275 * identities it can represent.
277 buffer_init(&request);
278 buffer_put_char(&request, code1);
280 buffer_clear(&auth->identities);
281 if (ssh_request_reply(auth, &request, &auth->identities) == 0) {
282 buffer_free(&request);
285 buffer_free(&request);
287 /* Get message type, and verify that we got a proper answer. */
288 type = buffer_get_char(&auth->identities);
289 if (agent_failed(type)) {
291 } else if (type != code2) {
292 fatal("Bad authentication reply message type: %d", type);
295 /* Get the number of entries in the response and check it for sanity. */
296 auth->howmany = buffer_get_int(&auth->identities);
297 if ((u_int)auth->howmany > 1024)
298 fatal("Too many identities in authentication reply: %d",
301 return auth->howmany;
305 ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version)
307 /* get number of identities and return the first entry (if any). */
308 if (ssh_get_num_identities(auth, version) > 0)
309 return ssh_get_next_identity(auth, comment, version);
314 ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version)
322 /* Return failure if no more entries. */
323 if (auth->howmany <= 0)
327 * Get the next entry from the packet. These will abort with a fatal
328 * error if the packet is too short or contains corrupt data.
332 key = key_new(KEY_RSA1);
333 bits = buffer_get_int(&auth->identities);
334 buffer_get_bignum(&auth->identities, key->rsa->e);
335 buffer_get_bignum(&auth->identities, key->rsa->n);
336 *comment = buffer_get_string(&auth->identities, NULL);
337 keybits = BN_num_bits(key->rsa->n);
338 if (keybits < 0 || bits != (u_int)keybits)
339 logit("Warning: identity keysize mismatch: actual %d, announced %u",
340 BN_num_bits(key->rsa->n), bits);
343 blob = buffer_get_string(&auth->identities, &blen);
344 *comment = buffer_get_string(&auth->identities, NULL);
345 key = key_from_blob(blob, blen);
351 /* Decrement the number of remaining entries. */
357 * Generates a random challenge, sends it to the agent, and waits for
358 * response from the agent. Returns true (non-zero) if the agent gave the
359 * correct answer, zero otherwise. Response type selects the style of
360 * response desired, with 0 corresponding to protocol version 1.0 (no longer
361 * supported) and 1 corresponding to protocol version 1.1.
365 ssh_decrypt_challenge(AuthenticationConnection *auth,
366 Key* key, BIGNUM *challenge,
367 u_char session_id[16],
376 if (key->type != KEY_RSA1)
378 if (response_type == 0) {
379 logit("Compatibility with ssh protocol version 1.0 no longer supported.");
382 buffer_init(&buffer);
383 buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE);
384 buffer_put_int(&buffer, BN_num_bits(key->rsa->n));
385 buffer_put_bignum(&buffer, key->rsa->e);
386 buffer_put_bignum(&buffer, key->rsa->n);
387 buffer_put_bignum(&buffer, challenge);
388 buffer_append(&buffer, session_id, 16);
389 buffer_put_int(&buffer, response_type);
391 if (ssh_request_reply(auth, &buffer, &buffer) == 0) {
392 buffer_free(&buffer);
395 type = buffer_get_char(&buffer);
397 if (agent_failed(type)) {
398 logit("Agent admitted failure to authenticate using the key.");
399 } else if (type != SSH_AGENT_RSA_RESPONSE) {
400 fatal("Bad authentication response: %d", type);
404 * Get the response from the packet. This will abort with a
405 * fatal error if the packet is corrupt.
407 for (i = 0; i < 16; i++)
408 response[i] = (u_char)buffer_get_char(&buffer);
410 buffer_free(&buffer);
414 /* ask agent to sign data, returns -1 on error, 0 on success */
416 ssh_agent_sign(AuthenticationConnection *auth,
418 u_char **sigp, u_int *lenp,
419 u_char *data, u_int datalen)
421 extern int datafellows;
428 if (key_to_blob(key, &blob, &blen) == 0)
431 if (datafellows & SSH_BUG_SIGBLOB)
432 flags = SSH_AGENT_OLD_SIGNATURE;
435 buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
436 buffer_put_string(&msg, blob, blen);
437 buffer_put_string(&msg, data, datalen);
438 buffer_put_int(&msg, flags);
441 if (ssh_request_reply(auth, &msg, &msg) == 0) {
445 type = buffer_get_char(&msg);
446 if (agent_failed(type)) {
447 logit("Agent admitted failure to sign using the key.");
448 } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
449 fatal("Bad authentication response: %d", type);
452 *sigp = buffer_get_string(&msg, lenp);
458 /* Encode key for a message to the agent. */
461 ssh_encode_identity_rsa1(Buffer *b, RSA *key, const char *comment)
463 buffer_put_int(b, BN_num_bits(key->n));
464 buffer_put_bignum(b, key->n);
465 buffer_put_bignum(b, key->e);
466 buffer_put_bignum(b, key->d);
467 /* To keep within the protocol: p < q for ssh. in SSL p > q */
468 buffer_put_bignum(b, key->iqmp); /* ssh key->u */
469 buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
470 buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
471 buffer_put_cstring(b, comment);
475 ssh_encode_identity_ssh2(Buffer *b, Key *key, const char *comment)
477 key_private_serialize(key, b);
478 buffer_put_cstring(b, comment);
482 * Adds an identity to the authentication server. This call is not meant to
483 * be used by normal applications.
487 ssh_add_identity_constrained(AuthenticationConnection *auth, Key *key,
488 const char *comment, u_int life, u_int confirm)
491 int type, constrained = (life || confirm);
498 SSH_AGENTC_ADD_RSA_ID_CONSTRAINED :
499 SSH_AGENTC_ADD_RSA_IDENTITY;
500 buffer_put_char(&msg, type);
501 ssh_encode_identity_rsa1(&msg, key->rsa, comment);
505 case KEY_RSA_CERT_V00:
508 case KEY_DSA_CERT_V00:
512 case KEY_ED25519_CERT:
514 SSH2_AGENTC_ADD_ID_CONSTRAINED :
515 SSH2_AGENTC_ADD_IDENTITY;
516 buffer_put_char(&msg, type);
517 ssh_encode_identity_ssh2(&msg, key, comment);
525 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
526 buffer_put_int(&msg, life);
529 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM);
531 if (ssh_request_reply(auth, &msg, &msg) == 0) {
535 type = buffer_get_char(&msg);
537 return decode_reply(type);
541 * Removes an identity from the authentication server. This call is not
542 * meant to be used by normal applications.
546 ssh_remove_identity(AuthenticationConnection *auth, Key *key)
555 if (key->type == KEY_RSA1) {
556 buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
557 buffer_put_int(&msg, BN_num_bits(key->rsa->n));
558 buffer_put_bignum(&msg, key->rsa->e);
559 buffer_put_bignum(&msg, key->rsa->n);
560 } else if (key->type != KEY_UNSPEC) {
561 key_to_blob(key, &blob, &blen);
562 buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
563 buffer_put_string(&msg, blob, blen);
569 if (ssh_request_reply(auth, &msg, &msg) == 0) {
573 type = buffer_get_char(&msg);
575 return decode_reply(type);
579 ssh_update_card(AuthenticationConnection *auth, int add,
580 const char *reader_id, const char *pin, u_int life, u_int confirm)
583 int type, constrained = (life || confirm);
587 SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED :
588 SSH_AGENTC_ADD_SMARTCARD_KEY;
590 type = SSH_AGENTC_REMOVE_SMARTCARD_KEY;
593 buffer_put_char(&msg, type);
594 buffer_put_cstring(&msg, reader_id);
595 buffer_put_cstring(&msg, pin);
599 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
600 buffer_put_int(&msg, life);
603 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM);
606 if (ssh_request_reply(auth, &msg, &msg) == 0) {
610 type = buffer_get_char(&msg);
612 return decode_reply(type);
616 * Removes all identities from the agent. This call is not meant to be used
617 * by normal applications.
621 ssh_remove_all_identities(AuthenticationConnection *auth, int version)
625 int code = (version==1) ?
626 SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
627 SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
630 buffer_put_char(&msg, code);
632 if (ssh_request_reply(auth, &msg, &msg) == 0) {
636 type = buffer_get_char(&msg);
638 return decode_reply(type);
642 decode_reply(int type)
645 case SSH_AGENT_FAILURE:
646 case SSH_COM_AGENT2_FAILURE:
647 case SSH2_AGENT_FAILURE:
648 logit("SSH_AGENT_FAILURE");
650 case SSH_AGENT_SUCCESS:
653 fatal("Bad response from authentication agent: %d", type);