1 /* $OpenBSD: authfd.c,v 1.93 2014/04/29 18:01:49 markus 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>
64 static int agent_present
= 0;
67 int decode_reply(int type
);
69 /* macro to check for "agent failure" message */
70 #define agent_failed(x) \
71 ((x == SSH_AGENT_FAILURE) || (x == SSH_COM_AGENT2_FAILURE) || \
72 (x == SSH2_AGENT_FAILURE))
75 ssh_agent_present(void)
81 if ((authfd
= ssh_get_authentication_socket()) == -1)
84 ssh_close_authentication_socket(authfd
);
89 /* Returns the number of the authentication fd, or -1 if there is none. */
92 ssh_get_authentication_socket(void)
94 const char *authsocket
;
96 struct sockaddr_un sunaddr
;
98 authsocket
= getenv(SSH_AUTHSOCKET_ENV_NAME
);
102 memset(&sunaddr
, 0, sizeof(sunaddr
));
103 sunaddr
.sun_family
= AF_UNIX
;
104 strlcpy(sunaddr
.sun_path
, authsocket
, sizeof(sunaddr
.sun_path
));
106 sock
= socket(AF_UNIX
, SOCK_STREAM
, 0);
111 if (fcntl(sock
, F_SETFD
, FD_CLOEXEC
) == -1) {
115 if (connect(sock
, (struct sockaddr
*)&sunaddr
, sizeof sunaddr
) < 0) {
124 ssh_request_reply(AuthenticationConnection
*auth
, Buffer
*request
, Buffer
*reply
)
129 /* Get the length of the message, and format it in the buffer. */
130 len
= buffer_len(request
);
133 /* Send the length and then the packet to the agent. */
134 if (atomicio(vwrite
, auth
->fd
, buf
, 4) != 4 ||
135 atomicio(vwrite
, auth
->fd
, buffer_ptr(request
),
136 buffer_len(request
)) != buffer_len(request
)) {
137 error("Error writing to authentication socket.");
141 * Wait for response from the agent. First read the length of the
144 if (atomicio(read
, auth
->fd
, buf
, 4) != 4) {
145 error("Error reading response length from authentication socket.");
149 /* Extract the length, and check it for sanity. */
151 if (len
> 256 * 1024)
152 fatal("Authentication response too long: %u", len
);
154 /* Read the rest of the response in to the buffer. */
160 if (atomicio(read
, auth
->fd
, buf
, l
) != l
) {
161 error("Error reading response from authentication socket.");
164 buffer_append(reply
, buf
, l
);
171 * Closes the agent socket if it should be closed (depends on how it was
172 * obtained). The argument must have been returned by
173 * ssh_get_authentication_socket().
177 ssh_close_authentication_socket(int sock
)
179 if (getenv(SSH_AUTHSOCKET_ENV_NAME
))
184 * Opens and connects a private socket for communication with the
185 * authentication agent. Returns the file descriptor (which must be
186 * shut down and closed by the caller when no longer needed).
187 * Returns NULL if an error occurred and the connection could not be
191 AuthenticationConnection
*
192 ssh_get_authentication_connection(void)
194 AuthenticationConnection
*auth
;
197 sock
= ssh_get_authentication_socket();
200 * Fail if we couldn't obtain a connection. This happens if we
201 * exited due to a timeout.
206 auth
= xcalloc(1, sizeof(*auth
));
208 buffer_init(&auth
->identities
);
215 * Closes the connection to the authentication agent and frees any associated
220 ssh_close_authentication_connection(AuthenticationConnection
*auth
)
222 buffer_free(&auth
->identities
);
227 /* Lock/unlock agent */
229 ssh_lock_agent(AuthenticationConnection
*auth
, int lock
, const char *password
)
235 buffer_put_char(&msg
, lock
? SSH_AGENTC_LOCK
: SSH_AGENTC_UNLOCK
);
236 buffer_put_cstring(&msg
, password
);
238 if (ssh_request_reply(auth
, &msg
, &msg
) == 0) {
242 type
= buffer_get_char(&msg
);
244 return decode_reply(type
);
248 * Returns the first authentication identity held by the agent.
252 ssh_get_num_identities(AuthenticationConnection
*auth
, int version
)
254 int type
, code1
= 0, code2
= 0;
259 code1
= SSH_AGENTC_REQUEST_RSA_IDENTITIES
;
260 code2
= SSH_AGENT_RSA_IDENTITIES_ANSWER
;
263 code1
= SSH2_AGENTC_REQUEST_IDENTITIES
;
264 code2
= SSH2_AGENT_IDENTITIES_ANSWER
;
271 * Send a message to the agent requesting for a list of the
272 * identities it can represent.
274 buffer_init(&request
);
275 buffer_put_char(&request
, code1
);
277 buffer_clear(&auth
->identities
);
278 if (ssh_request_reply(auth
, &request
, &auth
->identities
) == 0) {
279 buffer_free(&request
);
282 buffer_free(&request
);
284 /* Get message type, and verify that we got a proper answer. */
285 type
= buffer_get_char(&auth
->identities
);
286 if (agent_failed(type
)) {
288 } else if (type
!= code2
) {
289 fatal("Bad authentication reply message type: %d", type
);
292 /* Get the number of entries in the response and check it for sanity. */
293 auth
->howmany
= buffer_get_int(&auth
->identities
);
294 if ((u_int
)auth
->howmany
> 1024)
295 fatal("Too many identities in authentication reply: %d",
298 return auth
->howmany
;
302 ssh_get_first_identity(AuthenticationConnection
*auth
, char **comment
, int version
)
304 /* get number of identities and return the first entry (if any). */
305 if (ssh_get_num_identities(auth
, version
) > 0)
306 return ssh_get_next_identity(auth
, comment
, version
);
311 ssh_get_next_identity(AuthenticationConnection
*auth
, char **comment
, int version
)
321 /* Return failure if no more entries. */
322 if (auth
->howmany
<= 0)
326 * Get the next entry from the packet. These will abort with a fatal
327 * 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
);
344 blob
= buffer_get_string(&auth
->identities
, &blen
);
345 *comment
= buffer_get_string(&auth
->identities
, NULL
);
346 key
= key_from_blob(blob
, blen
);
352 /* Decrement the number of remaining entries. */
358 * Generates a random challenge, sends it to the agent, and waits for
359 * response from the agent. Returns true (non-zero) if the agent gave the
360 * correct answer, zero otherwise. Response type selects the style of
361 * response desired, with 0 corresponding to protocol version 1.0 (no longer
362 * supported) and 1 corresponding to protocol version 1.1.
367 ssh_decrypt_challenge(AuthenticationConnection
*auth
,
368 Key
* key
, BIGNUM
*challenge
,
369 u_char session_id
[16],
378 if (key
->type
!= KEY_RSA1
)
380 if (response_type
== 0) {
381 logit("Compatibility with ssh protocol version 1.0 no longer supported.");
384 buffer_init(&buffer
);
385 buffer_put_char(&buffer
, SSH_AGENTC_RSA_CHALLENGE
);
386 buffer_put_int(&buffer
, BN_num_bits(key
->rsa
->n
));
387 buffer_put_bignum(&buffer
, key
->rsa
->e
);
388 buffer_put_bignum(&buffer
, key
->rsa
->n
);
389 buffer_put_bignum(&buffer
, challenge
);
390 buffer_append(&buffer
, session_id
, 16);
391 buffer_put_int(&buffer
, response_type
);
393 if (ssh_request_reply(auth
, &buffer
, &buffer
) == 0) {
394 buffer_free(&buffer
);
397 type
= buffer_get_char(&buffer
);
399 if (agent_failed(type
)) {
400 logit("Agent admitted failure to authenticate using the key.");
401 } else if (type
!= SSH_AGENT_RSA_RESPONSE
) {
402 fatal("Bad authentication response: %d", type
);
406 * Get the response from the packet. This will abort with a
407 * fatal error if the packet is corrupt.
409 for (i
= 0; i
< 16; i
++)
410 response
[i
] = (u_char
)buffer_get_char(&buffer
);
412 buffer_free(&buffer
);
417 /* ask agent to sign data, returns -1 on error, 0 on success */
419 ssh_agent_sign(AuthenticationConnection
*auth
,
421 u_char
**sigp
, u_int
*lenp
,
422 u_char
*data
, u_int datalen
)
424 extern int datafellows
;
431 if (key_to_blob(key
, &blob
, &blen
) == 0)
434 if (datafellows
& SSH_BUG_SIGBLOB
)
435 flags
= SSH_AGENT_OLD_SIGNATURE
;
438 buffer_put_char(&msg
, SSH2_AGENTC_SIGN_REQUEST
);
439 buffer_put_string(&msg
, blob
, blen
);
440 buffer_put_string(&msg
, data
, datalen
);
441 buffer_put_int(&msg
, flags
);
444 if (ssh_request_reply(auth
, &msg
, &msg
) == 0) {
448 type
= buffer_get_char(&msg
);
449 if (agent_failed(type
)) {
450 logit("Agent admitted failure to sign using the key.");
451 } else if (type
!= SSH2_AGENT_SIGN_RESPONSE
) {
452 fatal("Bad authentication response: %d", type
);
455 *sigp
= buffer_get_string(&msg
, lenp
);
461 /* Encode key for a message to the agent. */
465 ssh_encode_identity_rsa1(Buffer
*b
, RSA
*key
, const char *comment
)
467 buffer_put_int(b
, BN_num_bits(key
->n
));
468 buffer_put_bignum(b
, key
->n
);
469 buffer_put_bignum(b
, key
->e
);
470 buffer_put_bignum(b
, key
->d
);
471 /* To keep within the protocol: p < q for ssh. in SSL p > q */
472 buffer_put_bignum(b
, key
->iqmp
); /* ssh key->u */
473 buffer_put_bignum(b
, key
->q
); /* ssh key->p, SSL key->q */
474 buffer_put_bignum(b
, key
->p
); /* ssh key->q, SSL key->p */
475 buffer_put_cstring(b
, comment
);
480 ssh_encode_identity_ssh2(Buffer
*b
, Key
*key
, const char *comment
)
482 key_private_serialize(key
, b
);
483 buffer_put_cstring(b
, comment
);
487 * Adds an identity to the authentication server. This call is not meant to
488 * be used by normal applications.
492 ssh_add_identity_constrained(AuthenticationConnection
*auth
, Key
*key
,
493 const char *comment
, u_int life
, u_int confirm
)
496 int type
, constrained
= (life
|| confirm
);
504 SSH_AGENTC_ADD_RSA_ID_CONSTRAINED
:
505 SSH_AGENTC_ADD_RSA_IDENTITY
;
506 buffer_put_char(&msg
, type
);
507 ssh_encode_identity_rsa1(&msg
, key
->rsa
, comment
);
513 case KEY_RSA_CERT_V00
:
516 case KEY_DSA_CERT_V00
:
521 case KEY_ED25519_CERT
:
523 SSH2_AGENTC_ADD_ID_CONSTRAINED
:
524 SSH2_AGENTC_ADD_IDENTITY
;
525 buffer_put_char(&msg
, type
);
526 ssh_encode_identity_ssh2(&msg
, key
, comment
);
534 buffer_put_char(&msg
, SSH_AGENT_CONSTRAIN_LIFETIME
);
535 buffer_put_int(&msg
, life
);
538 buffer_put_char(&msg
, SSH_AGENT_CONSTRAIN_CONFIRM
);
540 if (ssh_request_reply(auth
, &msg
, &msg
) == 0) {
544 type
= buffer_get_char(&msg
);
546 return decode_reply(type
);
550 * Removes an identity from the authentication server. This call is not
551 * meant to be used by normal applications.
555 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
);
572 if (key
->type
!= KEY_UNSPEC
) {
573 key_to_blob(key
, &blob
, &blen
);
574 buffer_put_char(&msg
, SSH2_AGENTC_REMOVE_IDENTITY
);
575 buffer_put_string(&msg
, blob
, blen
);
581 if (ssh_request_reply(auth
, &msg
, &msg
) == 0) {
585 type
= buffer_get_char(&msg
);
587 return decode_reply(type
);
591 ssh_update_card(AuthenticationConnection
*auth
, int add
,
592 const char *reader_id
, const char *pin
, u_int life
, u_int confirm
)
595 int type
, constrained
= (life
|| confirm
);
599 SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED
:
600 SSH_AGENTC_ADD_SMARTCARD_KEY
;
602 type
= SSH_AGENTC_REMOVE_SMARTCARD_KEY
;
605 buffer_put_char(&msg
, type
);
606 buffer_put_cstring(&msg
, reader_id
);
607 buffer_put_cstring(&msg
, pin
);
611 buffer_put_char(&msg
, SSH_AGENT_CONSTRAIN_LIFETIME
);
612 buffer_put_int(&msg
, life
);
615 buffer_put_char(&msg
, SSH_AGENT_CONSTRAIN_CONFIRM
);
618 if (ssh_request_reply(auth
, &msg
, &msg
) == 0) {
622 type
= buffer_get_char(&msg
);
624 return decode_reply(type
);
628 * Removes all identities from the agent. This call is not meant to be used
629 * by normal applications.
633 ssh_remove_all_identities(AuthenticationConnection
*auth
, int version
)
637 int code
= (version
==1) ?
638 SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES
:
639 SSH2_AGENTC_REMOVE_ALL_IDENTITIES
;
642 buffer_put_char(&msg
, code
);
644 if (ssh_request_reply(auth
, &msg
, &msg
) == 0) {
648 type
= buffer_get_char(&msg
);
650 return decode_reply(type
);
654 decode_reply(int type
)
657 case SSH_AGENT_FAILURE
:
658 case SSH_COM_AGENT2_FAILURE
:
659 case SSH2_AGENT_FAILURE
:
660 logit("SSH_AGENT_FAILURE");
662 case SSH_AGENT_SUCCESS
:
665 fatal("Bad response from authentication agent: %d", type
);