1 /* $OpenBSD: authfd.c,v 1.74 2006/03/30 09:58:15 djm 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>
43 #include <openssl/evp.h>
59 static int agent_present = 0;
62 int decode_reply(int type);
64 /* macro to check for "agent failure" message */
65 #define agent_failed(x) \
66 ((x == SSH_AGENT_FAILURE) || (x == SSH_COM_AGENT2_FAILURE) || \
67 (x == SSH2_AGENT_FAILURE))
70 ssh_agent_present(void)
76 if ((authfd = ssh_get_authentication_socket()) == -1)
79 ssh_close_authentication_socket(authfd);
84 /* Returns the number of the authentication fd, or -1 if there is none. */
87 ssh_get_authentication_socket(void)
89 const char *authsocket;
91 struct sockaddr_un sunaddr;
93 authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
97 sunaddr.sun_family = AF_UNIX;
98 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
100 sock = socket(AF_UNIX, SOCK_STREAM, 0);
105 if (fcntl(sock, F_SETFD, 1) == -1) {
109 if (connect(sock, (struct sockaddr *)&sunaddr, sizeof sunaddr) < 0) {
118 ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply)
123 /* Get the length of the message, and format it in the buffer. */
124 len = buffer_len(request);
127 /* Send the length and then the packet to the agent. */
128 if (atomicio(vwrite, auth->fd, buf, 4) != 4 ||
129 atomicio(vwrite, auth->fd, buffer_ptr(request),
130 buffer_len(request)) != buffer_len(request)) {
131 error("Error writing to authentication socket.");
135 * Wait for response from the agent. First read the length of the
138 if (atomicio(read, auth->fd, buf, 4) != 4) {
139 error("Error reading response length from authentication socket.");
143 /* Extract the length, and check it for sanity. */
145 if (len > 256 * 1024)
146 fatal("Authentication response too long: %u", len);
148 /* Read the rest of the response in to the buffer. */
154 if (atomicio(read, auth->fd, buf, l) != l) {
155 error("Error reading response from authentication socket.");
158 buffer_append(reply, buf, l);
165 * Closes the agent socket if it should be closed (depends on how it was
166 * obtained). The argument must have been returned by
167 * ssh_get_authentication_socket().
171 ssh_close_authentication_socket(int sock)
173 if (getenv(SSH_AUTHSOCKET_ENV_NAME))
178 * Opens and connects a private socket for communication with the
179 * authentication agent. Returns the file descriptor (which must be
180 * shut down and closed by the caller when no longer needed).
181 * Returns NULL if an error occurred and the connection could not be
185 AuthenticationConnection *
186 ssh_get_authentication_connection(void)
188 AuthenticationConnection *auth;
191 sock = ssh_get_authentication_socket();
194 * Fail if we couldn't obtain a connection. This happens if we
195 * exited due to a timeout.
200 auth = xmalloc(sizeof(*auth));
202 buffer_init(&auth->identities);
209 * Closes the connection to the authentication agent and frees any associated
214 ssh_close_authentication_connection(AuthenticationConnection *auth)
216 buffer_free(&auth->identities);
221 /* Lock/unlock agent */
223 ssh_lock_agent(AuthenticationConnection *auth, int lock, const char *password)
229 buffer_put_char(&msg, lock ? SSH_AGENTC_LOCK : SSH_AGENTC_UNLOCK);
230 buffer_put_cstring(&msg, password);
232 if (ssh_request_reply(auth, &msg, &msg) == 0) {
236 type = buffer_get_char(&msg);
238 return decode_reply(type);
242 * Returns the first authentication identity held by the agent.
246 ssh_get_num_identities(AuthenticationConnection *auth, int version)
248 int type, code1 = 0, code2 = 0;
253 code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
254 code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
257 code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
258 code2 = SSH2_AGENT_IDENTITIES_ANSWER;
265 * Send a message to the agent requesting for a list of the
266 * identities it can represent.
268 buffer_init(&request);
269 buffer_put_char(&request, code1);
271 buffer_clear(&auth->identities);
272 if (ssh_request_reply(auth, &request, &auth->identities) == 0) {
273 buffer_free(&request);
276 buffer_free(&request);
278 /* Get message type, and verify that we got a proper answer. */
279 type = buffer_get_char(&auth->identities);
280 if (agent_failed(type)) {
282 } else if (type != code2) {
283 fatal("Bad authentication reply message type: %d", type);
286 /* Get the number of entries in the response and check it for sanity. */
287 auth->howmany = buffer_get_int(&auth->identities);
288 if ((u_int)auth->howmany > 1024)
289 fatal("Too many identities in authentication reply: %d",
292 return auth->howmany;
296 ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version)
298 /* get number of identities and return the first entry (if any). */
299 if (ssh_get_num_identities(auth, version) > 0)
300 return ssh_get_next_identity(auth, comment, version);
305 ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version)
313 /* Return failure if no more entries. */
314 if (auth->howmany <= 0)
318 * Get the next entry from the packet. These will abort with a fatal
319 * error if the packet is too short or contains corrupt data.
323 key = key_new(KEY_RSA1);
324 bits = buffer_get_int(&auth->identities);
325 buffer_get_bignum(&auth->identities, key->rsa->e);
326 buffer_get_bignum(&auth->identities, key->rsa->n);
327 *comment = buffer_get_string(&auth->identities, NULL);
328 keybits = BN_num_bits(key->rsa->n);
329 if (keybits < 0 || bits != (u_int)keybits)
330 logit("Warning: identity keysize mismatch: actual %d, announced %u",
331 BN_num_bits(key->rsa->n), bits);
334 blob = buffer_get_string(&auth->identities, &blen);
335 *comment = buffer_get_string(&auth->identities, NULL);
336 key = key_from_blob(blob, blen);
342 /* Decrement the number of remaining entries. */
348 * Generates a random challenge, sends it to the agent, and waits for
349 * response from the agent. Returns true (non-zero) if the agent gave the
350 * correct answer, zero otherwise. Response type selects the style of
351 * response desired, with 0 corresponding to protocol version 1.0 (no longer
352 * supported) and 1 corresponding to protocol version 1.1.
356 ssh_decrypt_challenge(AuthenticationConnection *auth,
357 Key* key, BIGNUM *challenge,
358 u_char session_id[16],
367 if (key->type != KEY_RSA1)
369 if (response_type == 0) {
370 logit("Compatibility with ssh protocol version 1.0 no longer supported.");
373 buffer_init(&buffer);
374 buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE);
375 buffer_put_int(&buffer, BN_num_bits(key->rsa->n));
376 buffer_put_bignum(&buffer, key->rsa->e);
377 buffer_put_bignum(&buffer, key->rsa->n);
378 buffer_put_bignum(&buffer, challenge);
379 buffer_append(&buffer, session_id, 16);
380 buffer_put_int(&buffer, response_type);
382 if (ssh_request_reply(auth, &buffer, &buffer) == 0) {
383 buffer_free(&buffer);
386 type = buffer_get_char(&buffer);
388 if (agent_failed(type)) {
389 logit("Agent admitted failure to authenticate using the key.");
390 } else if (type != SSH_AGENT_RSA_RESPONSE) {
391 fatal("Bad authentication response: %d", type);
395 * Get the response from the packet. This will abort with a
396 * fatal error if the packet is corrupt.
398 for (i = 0; i < 16; i++)
399 response[i] = (u_char)buffer_get_char(&buffer);
401 buffer_free(&buffer);
405 /* ask agent to sign data, returns -1 on error, 0 on success */
407 ssh_agent_sign(AuthenticationConnection *auth,
409 u_char **sigp, u_int *lenp,
410 u_char *data, u_int datalen)
412 extern int datafellows;
419 if (key_to_blob(key, &blob, &blen) == 0)
422 if (datafellows & SSH_BUG_SIGBLOB)
423 flags = SSH_AGENT_OLD_SIGNATURE;
426 buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
427 buffer_put_string(&msg, blob, blen);
428 buffer_put_string(&msg, data, datalen);
429 buffer_put_int(&msg, flags);
432 if (ssh_request_reply(auth, &msg, &msg) == 0) {
436 type = buffer_get_char(&msg);
437 if (agent_failed(type)) {
438 logit("Agent admitted failure to sign using the key.");
439 } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
440 fatal("Bad authentication response: %d", type);
443 *sigp = buffer_get_string(&msg, lenp);
449 /* Encode key for a message to the agent. */
452 ssh_encode_identity_rsa1(Buffer *b, RSA *key, const char *comment)
454 buffer_put_int(b, BN_num_bits(key->n));
455 buffer_put_bignum(b, key->n);
456 buffer_put_bignum(b, key->e);
457 buffer_put_bignum(b, key->d);
458 /* To keep within the protocol: p < q for ssh. in SSL p > q */
459 buffer_put_bignum(b, key->iqmp); /* ssh key->u */
460 buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
461 buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
462 buffer_put_cstring(b, comment);
466 ssh_encode_identity_ssh2(Buffer *b, Key *key, const char *comment)
468 buffer_put_cstring(b, key_ssh_name(key));
471 buffer_put_bignum2(b, key->rsa->n);
472 buffer_put_bignum2(b, key->rsa->e);
473 buffer_put_bignum2(b, key->rsa->d);
474 buffer_put_bignum2(b, key->rsa->iqmp);
475 buffer_put_bignum2(b, key->rsa->p);
476 buffer_put_bignum2(b, key->rsa->q);
479 buffer_put_bignum2(b, key->dsa->p);
480 buffer_put_bignum2(b, key->dsa->q);
481 buffer_put_bignum2(b, key->dsa->g);
482 buffer_put_bignum2(b, key->dsa->pub_key);
483 buffer_put_bignum2(b, key->dsa->priv_key);
486 buffer_put_cstring(b, comment);
490 * Adds an identity to the authentication server. This call is not meant to
491 * be used by normal applications.
495 ssh_add_identity_constrained(AuthenticationConnection *auth, Key *key,
496 const char *comment, u_int life, u_int confirm)
499 int type, constrained = (life || confirm);
506 SSH_AGENTC_ADD_RSA_ID_CONSTRAINED :
507 SSH_AGENTC_ADD_RSA_IDENTITY;
508 buffer_put_char(&msg, type);
509 ssh_encode_identity_rsa1(&msg, key->rsa, comment);
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 ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
543 return ssh_add_identity_constrained(auth, key, comment, 0, 0);
547 * Removes an identity from the authentication server. This call is not
548 * meant to be used by normal applications.
552 ssh_remove_identity(AuthenticationConnection *auth, Key *key)
561 if (key->type == KEY_RSA1) {
562 buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
563 buffer_put_int(&msg, BN_num_bits(key->rsa->n));
564 buffer_put_bignum(&msg, key->rsa->e);
565 buffer_put_bignum(&msg, key->rsa->n);
566 } else if (key->type == KEY_DSA || key->type == KEY_RSA) {
567 key_to_blob(key, &blob, &blen);
568 buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
569 buffer_put_string(&msg, blob, blen);
575 if (ssh_request_reply(auth, &msg, &msg) == 0) {
579 type = buffer_get_char(&msg);
581 return decode_reply(type);
585 ssh_update_card(AuthenticationConnection *auth, int add,
586 const char *reader_id, const char *pin, u_int life, u_int confirm)
589 int type, constrained = (life || confirm);
593 SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED :
594 SSH_AGENTC_ADD_SMARTCARD_KEY;
596 type = SSH_AGENTC_REMOVE_SMARTCARD_KEY;
599 buffer_put_char(&msg, type);
600 buffer_put_cstring(&msg, reader_id);
601 buffer_put_cstring(&msg, pin);
605 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_LIFETIME);
606 buffer_put_int(&msg, life);
609 buffer_put_char(&msg, SSH_AGENT_CONSTRAIN_CONFIRM);
612 if (ssh_request_reply(auth, &msg, &msg) == 0) {
616 type = buffer_get_char(&msg);
618 return decode_reply(type);
622 * Removes all identities from the agent. This call is not meant to be used
623 * by normal applications.
627 ssh_remove_all_identities(AuthenticationConnection *auth, int version)
631 int code = (version==1) ?
632 SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
633 SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
636 buffer_put_char(&msg, code);
638 if (ssh_request_reply(auth, &msg, &msg) == 0) {
642 type = buffer_get_char(&msg);
644 return decode_reply(type);
648 decode_reply(int type)
651 case SSH_AGENT_FAILURE:
652 case SSH_COM_AGENT2_FAILURE:
653 case SSH2_AGENT_FAILURE:
654 logit("SSH_AGENT_FAILURE");
656 case SSH_AGENT_SUCCESS:
659 fatal("Bad response from authentication agent: %d", type);