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- markus@cvs.openbsd.org 2001/08/07 10:37:46
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8efc0c15 1/*
5260325f 2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
5260325f 3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
5260325f 5 * Functions for connecting the local authentication agent.
6ae2364d 6 *
bcbf86ec 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".
12 *
2e73a022 13 * SSH2 implementation,
bcbf86ec 14 * Copyright (c) 2000 Markus Friedl. All rights reserved.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions
18 * are met:
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.
2e73a022 24 *
bcbf86ec 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.
5260325f 35 */
8efc0c15 36
37#include "includes.h"
65e683bd 38RCSID("$OpenBSD: authfd.c,v 1.44 2001/08/07 10:37:46 markus Exp $");
42f11eb2 39
40#include <openssl/evp.h>
8efc0c15 41
42#include "ssh.h"
43#include "rsa.h"
8efc0c15 44#include "buffer.h"
45#include "bufaux.h"
46#include "xmalloc.h"
47#include "getput.h"
4c8722d9 48#include "key.h"
49#include "authfd.h"
42f11eb2 50#include "cipher.h"
4c8722d9 51#include "kex.h"
188adeb2 52#include "compat.h"
42f11eb2 53#include "log.h"
54#include "atomicio.h"
8efc0c15 55
089fbbd2 56/* helper */
c345cf9d 57int decode_reply(int type);
089fbbd2 58
94ec8c6b 59/* macro to check for "agent failure" message */
60#define agent_failed(x) \
65e683bd 61 ((x == SSH_AGENT_FAILURE) || (x == SSH_COM_AGENT2_FAILURE) || \
62 (x == SSH2_AGENT_FAILURE))
94ec8c6b 63
8efc0c15 64/* Returns the number of the authentication fd, or -1 if there is none. */
65
66int
1e3b8b07 67ssh_get_authentication_socket(void)
8efc0c15 68{
5260325f 69 const char *authsocket;
c345cf9d 70 int sock, len;
5260325f 71 struct sockaddr_un sunaddr;
72
73 authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME);
74 if (!authsocket)
75 return -1;
76
77 sunaddr.sun_family = AF_UNIX;
78 strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path));
c345cf9d 79 len = SUN_LEN(&sunaddr)+1;
c3f7d267 80#ifdef HAVE_SUN_LEN_IN_SOCKADDR_UN
81 sunaddr.sun_len = len;
c345cf9d 82#endif /* HAVE_SUN_LEN_IN_SOCKADDR_UN */
5260325f 83
84 sock = socket(AF_UNIX, SOCK_STREAM, 0);
85 if (sock < 0)
86 return -1;
87
88 /* close on exec */
89 if (fcntl(sock, F_SETFD, 1) == -1) {
90 close(sock);
91 return -1;
92 }
c345cf9d 93 if (connect(sock, (struct sockaddr *) & sunaddr, len) < 0) {
5260325f 94 close(sock);
95 return -1;
96 }
97 return sock;
8efc0c15 98}
99
396c147e 100static int
2e73a022 101ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply)
c345cf9d 102{
103 int l, len;
104 char buf[1024];
105
106 /* Get the length of the message, and format it in the buffer. */
107 len = buffer_len(request);
108 PUT_32BIT(buf, len);
109
110 /* Send the length and then the packet to the agent. */
111 if (atomicio(write, auth->fd, buf, 4) != 4 ||
112 atomicio(write, auth->fd, buffer_ptr(request),
113 buffer_len(request)) != buffer_len(request)) {
114 error("Error writing to authentication socket.");
115 return 0;
116 }
117 /*
118 * Wait for response from the agent. First read the length of the
119 * response packet.
120 */
121 len = 4;
122 while (len > 0) {
123 l = read(auth->fd, buf + 4 - len, len);
bbc62e59 124 if (l == -1 && (errno == EAGAIN || errno == EINTR))
cd332296 125 continue;
c345cf9d 126 if (l <= 0) {
127 error("Error reading response length from authentication socket.");
128 return 0;
129 }
130 len -= l;
131 }
132
133 /* Extract the length, and check it for sanity. */
134 len = GET_32BIT(buf);
135 if (len > 256 * 1024)
136 fatal("Authentication response too long: %d", len);
137
138 /* Read the rest of the response in to the buffer. */
139 buffer_clear(reply);
140 while (len > 0) {
141 l = len;
142 if (l > sizeof(buf))
143 l = sizeof(buf);
144 l = read(auth->fd, buf, l);
bbc62e59 145 if (l == -1 && (errno == EAGAIN || errno == EINTR))
cd332296 146 continue;
c345cf9d 147 if (l <= 0) {
148 error("Error reading response from authentication socket.");
149 return 0;
150 }
151 buffer_append(reply, (char *) buf, l);
152 len -= l;
153 }
154 return 1;
155}
156
aa3378df 157/*
158 * Closes the agent socket if it should be closed (depends on how it was
159 * obtained). The argument must have been returned by
160 * ssh_get_authentication_socket().
161 */
8efc0c15 162
6ae2364d 163void
5260325f 164ssh_close_authentication_socket(int sock)
8efc0c15 165{
5260325f 166 if (getenv(SSH_AUTHSOCKET_ENV_NAME))
167 close(sock);
8efc0c15 168}
169
aa3378df 170/*
171 * Opens and connects a private socket for communication with the
172 * authentication agent. Returns the file descriptor (which must be
173 * shut down and closed by the caller when no longer needed).
174 * Returns NULL if an error occurred and the connection could not be
175 * opened.
176 */
8efc0c15 177
5260325f 178AuthenticationConnection *
1e3b8b07 179ssh_get_authentication_connection(void)
8efc0c15 180{
5260325f 181 AuthenticationConnection *auth;
182 int sock;
183
184 sock = ssh_get_authentication_socket();
185
aa3378df 186 /*
187 * Fail if we couldn't obtain a connection. This happens if we
188 * exited due to a timeout.
189 */
5260325f 190 if (sock < 0)
191 return NULL;
192
5260325f 193 auth = xmalloc(sizeof(*auth));
194 auth->fd = sock;
5260325f 195 buffer_init(&auth->identities);
196 auth->howmany = 0;
197
198 return auth;
8efc0c15 199}
200
aa3378df 201/*
202 * Closes the connection to the authentication agent and frees any associated
203 * memory.
204 */
8efc0c15 205
6ae2364d 206void
2e73a022 207ssh_close_authentication_connection(AuthenticationConnection *auth)
8efc0c15 208{
2e73a022 209 buffer_free(&auth->identities);
210 close(auth->fd);
211 xfree(auth);
8efc0c15 212}
213
aa3378df 214/*
215 * Returns the first authentication identity held by the agent.
aa3378df 216 */
8efc0c15 217
fa08c86b 218int
219ssh_get_num_identities(AuthenticationConnection *auth, int version)
8efc0c15 220{
2e73a022 221 int type, code1 = 0, code2 = 0;
c345cf9d 222 Buffer request;
2e73a022 223
224 switch(version){
225 case 1:
226 code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES;
227 code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER;
228 break;
229 case 2:
230 code1 = SSH2_AGENTC_REQUEST_IDENTITIES;
231 code2 = SSH2_AGENT_IDENTITIES_ANSWER;
232 break;
233 default:
fa08c86b 234 return 0;
2e73a022 235 }
5260325f 236
aa3378df 237 /*
238 * Send a message to the agent requesting for a list of the
239 * identities it can represent.
240 */
c345cf9d 241 buffer_init(&request);
2e73a022 242 buffer_put_char(&request, code1);
5260325f 243
5260325f 244 buffer_clear(&auth->identities);
c345cf9d 245 if (ssh_request_reply(auth, &request, &auth->identities) == 0) {
246 buffer_free(&request);
fa08c86b 247 return 0;
8efc0c15 248 }
c345cf9d 249 buffer_free(&request);
5260325f 250
251 /* Get message type, and verify that we got a proper answer. */
c345cf9d 252 type = buffer_get_char(&auth->identities);
94ec8c6b 253 if (agent_failed(type)) {
fa08c86b 254 return 0;
2e73a022 255 } else if (type != code2) {
c345cf9d 256 fatal("Bad authentication reply message type: %d", type);
2e73a022 257 }
5260325f 258
259 /* Get the number of entries in the response and check it for sanity. */
260 auth->howmany = buffer_get_int(&auth->identities);
261 if (auth->howmany > 1024)
54b974dc 262 fatal("Too many identities in authentication reply: %d",
c345cf9d 263 auth->howmany);
5260325f 264
fa08c86b 265 return auth->howmany;
266}
267
268Key *
269ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version)
270{
271 /* get number of identities and return the first entry (if any). */
272 if (ssh_get_num_identities(auth, version) > 0)
273 return ssh_get_next_identity(auth, comment, version);
274 return NULL;
8efc0c15 275}
276
2e73a022 277Key *
278ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version)
8efc0c15 279{
1e3b8b07 280 u_int bits;
281 u_char *blob;
282 u_int blen;
2e73a022 283 Key *key = NULL;
4d195447 284
5260325f 285 /* Return failure if no more entries. */
286 if (auth->howmany <= 0)
2e73a022 287 return NULL;
8efc0c15 288
aa3378df 289 /*
290 * Get the next entry from the packet. These will abort with a fatal
291 * error if the packet is too short or contains corrupt data.
292 */
2e73a022 293 switch(version){
294 case 1:
fa08c86b 295 key = key_new(KEY_RSA1);
2e73a022 296 bits = buffer_get_int(&auth->identities);
297 buffer_get_bignum(&auth->identities, key->rsa->e);
298 buffer_get_bignum(&auth->identities, key->rsa->n);
299 *comment = buffer_get_string(&auth->identities, NULL);
300 if (bits != BN_num_bits(key->rsa->n))
301 log("Warning: identity keysize mismatch: actual %d, announced %u",
302 BN_num_bits(key->rsa->n), bits);
303 break;
304 case 2:
305 blob = buffer_get_string(&auth->identities, &blen);
306 *comment = buffer_get_string(&auth->identities, NULL);
fa08c86b 307 key = key_from_blob(blob, blen);
2e73a022 308 xfree(blob);
309 break;
310 default:
311 return NULL;
312 break;
313 }
5260325f 314 /* Decrement the number of remaining entries. */
315 auth->howmany--;
2e73a022 316 return key;
8efc0c15 317}
318
aa3378df 319/*
320 * Generates a random challenge, sends it to the agent, and waits for
321 * response from the agent. Returns true (non-zero) if the agent gave the
322 * correct answer, zero otherwise. Response type selects the style of
323 * response desired, with 0 corresponding to protocol version 1.0 (no longer
324 * supported) and 1 corresponding to protocol version 1.1.
325 */
8efc0c15 326
327int
328ssh_decrypt_challenge(AuthenticationConnection *auth,
2e73a022 329 Key* key, BIGNUM *challenge,
1e3b8b07 330 u_char session_id[16],
331 u_int response_type,
332 u_char response[16])
8efc0c15 333{
5260325f 334 Buffer buffer;
c345cf9d 335 int success = 0;
336 int i;
337 int type;
5260325f 338
fa08c86b 339 if (key->type != KEY_RSA1)
2e73a022 340 return 0;
341 if (response_type == 0) {
342 log("Compatibility with ssh protocol version 1.0 no longer supported.");
343 return 0;
344 }
5260325f 345 buffer_init(&buffer);
c345cf9d 346 buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE);
2e73a022 347 buffer_put_int(&buffer, BN_num_bits(key->rsa->n));
348 buffer_put_bignum(&buffer, key->rsa->e);
349 buffer_put_bignum(&buffer, key->rsa->n);
5260325f 350 buffer_put_bignum(&buffer, challenge);
351 buffer_append(&buffer, (char *) session_id, 16);
352 buffer_put_int(&buffer, response_type);
353
c345cf9d 354 if (ssh_request_reply(auth, &buffer, &buffer) == 0) {
5260325f 355 buffer_free(&buffer);
356 return 0;
357 }
c345cf9d 358 type = buffer_get_char(&buffer);
5260325f 359
94ec8c6b 360 if (agent_failed(type)) {
5260325f 361 log("Agent admitted failure to authenticate using the key.");
c345cf9d 362 } else if (type != SSH_AGENT_RSA_RESPONSE) {
363 fatal("Bad authentication response: %d", type);
364 } else {
365 success = 1;
366 /*
367 * Get the response from the packet. This will abort with a
368 * fatal error if the packet is corrupt.
369 */
370 for (i = 0; i < 16; i++)
371 response[i] = buffer_get_char(&buffer);
8efc0c15 372 }
5260325f 373 buffer_free(&buffer);
c345cf9d 374 return success;
5260325f 375}
8efc0c15 376
2e73a022 377/* ask agent to sign data, returns -1 on error, 0 on success */
378int
379ssh_agent_sign(AuthenticationConnection *auth,
380 Key *key,
1e3b8b07 381 u_char **sigp, int *lenp,
382 u_char *data, int datalen)
2e73a022 383{
188adeb2 384 extern int datafellows;
2e73a022 385 Buffer msg;
1e3b8b07 386 u_char *blob;
387 u_int blen;
188adeb2 388 int type, flags = 0;
2e73a022 389 int ret = -1;
390
fa08c86b 391 if (key_to_blob(key, &blob, &blen) == 0)
2e73a022 392 return -1;
393
188adeb2 394 if (datafellows & SSH_BUG_SIGBLOB)
395 flags = SSH_AGENT_OLD_SIGNATURE;
396
2e73a022 397 buffer_init(&msg);
398 buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST);
399 buffer_put_string(&msg, blob, blen);
400 buffer_put_string(&msg, data, datalen);
188adeb2 401 buffer_put_int(&msg, flags);
2e73a022 402 xfree(blob);
403
404 if (ssh_request_reply(auth, &msg, &msg) == 0) {
405 buffer_free(&msg);
406 return -1;
407 }
408 type = buffer_get_char(&msg);
94ec8c6b 409 if (agent_failed(type)) {
2e73a022 410 log("Agent admitted failure to sign using the key.");
411 } else if (type != SSH2_AGENT_SIGN_RESPONSE) {
412 fatal("Bad authentication response: %d", type);
413 } else {
414 ret = 0;
415 *sigp = buffer_get_string(&msg, lenp);
416 }
417 buffer_free(&msg);
418 return ret;
419}
420
4c8722d9 421/* Encode key for a message to the agent. */
422
396c147e 423static void
fa08c86b 424ssh_encode_identity_rsa1(Buffer *b, RSA *key, const char *comment)
4c8722d9 425{
426 buffer_clear(b);
427 buffer_put_char(b, SSH_AGENTC_ADD_RSA_IDENTITY);
428 buffer_put_int(b, BN_num_bits(key->n));
429 buffer_put_bignum(b, key->n);
430 buffer_put_bignum(b, key->e);
431 buffer_put_bignum(b, key->d);
432 /* To keep within the protocol: p < q for ssh. in SSL p > q */
433 buffer_put_bignum(b, key->iqmp); /* ssh key->u */
434 buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */
435 buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */
449c5ba5 436 buffer_put_cstring(b, comment);
4c8722d9 437}
438
396c147e 439static void
fa08c86b 440ssh_encode_identity_ssh2(Buffer *b, Key *key, const char *comment)
4c8722d9 441{
442 buffer_clear(b);
443 buffer_put_char(b, SSH2_AGENTC_ADD_IDENTITY);
fa08c86b 444 buffer_put_cstring(b, key_ssh_name(key));
445 switch(key->type){
446 case KEY_RSA:
447 buffer_put_bignum2(b, key->rsa->n);
448 buffer_put_bignum2(b, key->rsa->e);
449 buffer_put_bignum2(b, key->rsa->d);
450 buffer_put_bignum2(b, key->rsa->iqmp);
451 buffer_put_bignum2(b, key->rsa->p);
452 buffer_put_bignum2(b, key->rsa->q);
453 break;
454 case KEY_DSA:
455 buffer_put_bignum2(b, key->dsa->p);
456 buffer_put_bignum2(b, key->dsa->q);
457 buffer_put_bignum2(b, key->dsa->g);
458 buffer_put_bignum2(b, key->dsa->pub_key);
459 buffer_put_bignum2(b, key->dsa->priv_key);
460 break;
461 }
462 buffer_put_cstring(b, comment);
4c8722d9 463}
464
aa3378df 465/*
466 * Adds an identity to the authentication server. This call is not meant to
467 * be used by normal applications.
468 */
8efc0c15 469
6ae2364d 470int
4c8722d9 471ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment)
8efc0c15 472{
2e73a022 473 Buffer msg;
c345cf9d 474 int type;
5260325f 475
2e73a022 476 buffer_init(&msg);
4c8722d9 477
478 switch (key->type) {
fa08c86b 479 case KEY_RSA1:
480 ssh_encode_identity_rsa1(&msg, key->rsa, comment);
4c8722d9 481 break;
fa08c86b 482 case KEY_RSA:
4c8722d9 483 case KEY_DSA:
fa08c86b 484 ssh_encode_identity_ssh2(&msg, key, comment);
4c8722d9 485 break;
486 default:
2e73a022 487 buffer_free(&msg);
4c8722d9 488 return 0;
489 break;
490 }
2e73a022 491 if (ssh_request_reply(auth, &msg, &msg) == 0) {
492 buffer_free(&msg);
5260325f 493 return 0;
494 }
2e73a022 495 type = buffer_get_char(&msg);
496 buffer_free(&msg);
c345cf9d 497 return decode_reply(type);
5260325f 498}
499
aa3378df 500/*
501 * Removes an identity from the authentication server. This call is not
502 * meant to be used by normal applications.
503 */
8efc0c15 504
6ae2364d 505int
2e73a022 506ssh_remove_identity(AuthenticationConnection *auth, Key *key)
8efc0c15 507{
2e73a022 508 Buffer msg;
c345cf9d 509 int type;
1e3b8b07 510 u_char *blob;
511 u_int blen;
2e73a022 512
513 buffer_init(&msg);
514
fa08c86b 515 if (key->type == KEY_RSA1) {
2e73a022 516 buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY);
517 buffer_put_int(&msg, BN_num_bits(key->rsa->n));
518 buffer_put_bignum(&msg, key->rsa->e);
519 buffer_put_bignum(&msg, key->rsa->n);
fa08c86b 520 } else if (key->type == KEY_DSA || key->type == KEY_RSA) {
521 key_to_blob(key, &blob, &blen);
2e73a022 522 buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY);
523 buffer_put_string(&msg, blob, blen);
524 xfree(blob);
525 } else {
526 buffer_free(&msg);
5260325f 527 return 0;
528 }
2e73a022 529 if (ssh_request_reply(auth, &msg, &msg) == 0) {
530 buffer_free(&msg);
531 return 0;
532 }
533 type = buffer_get_char(&msg);
534 buffer_free(&msg);
c345cf9d 535 return decode_reply(type);
5260325f 536}
537
983def13 538int
9ff6f66f 539ssh_update_card(AuthenticationConnection *auth, int add, const char *reader_id)
983def13 540{
541 Buffer msg;
542 int type;
543
544 buffer_init(&msg);
545 buffer_put_char(&msg, add ? SSH_AGENTC_ADD_SMARTCARD_KEY :
546 SSH_AGENTC_REMOVE_SMARTCARD_KEY);
9ff6f66f 547 buffer_put_cstring(&msg, reader_id);
983def13 548 if (ssh_request_reply(auth, &msg, &msg) == 0) {
549 buffer_free(&msg);
550 return 0;
551 }
552 type = buffer_get_char(&msg);
553 buffer_free(&msg);
554 return decode_reply(type);
555}
556
aa3378df 557/*
558 * Removes all identities from the agent. This call is not meant to be used
559 * by normal applications.
560 */
8efc0c15 561
6ae2364d 562int
2e73a022 563ssh_remove_all_identities(AuthenticationConnection *auth, int version)
8efc0c15 564{
2e73a022 565 Buffer msg;
c345cf9d 566 int type;
2e73a022 567 int code = (version==1) ?
568 SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES :
569 SSH2_AGENTC_REMOVE_ALL_IDENTITIES;
5260325f 570
2e73a022 571 buffer_init(&msg);
572 buffer_put_char(&msg, code);
5260325f 573
2e73a022 574 if (ssh_request_reply(auth, &msg, &msg) == 0) {
575 buffer_free(&msg);
5260325f 576 return 0;
577 }
2e73a022 578 type = buffer_get_char(&msg);
579 buffer_free(&msg);
c345cf9d 580 return decode_reply(type);
089fbbd2 581}
582
2b87da3b 583int
c345cf9d 584decode_reply(int type)
089fbbd2 585{
5260325f 586 switch (type) {
587 case SSH_AGENT_FAILURE:
94ec8c6b 588 case SSH_COM_AGENT2_FAILURE:
65e683bd 589 case SSH2_AGENT_FAILURE:
c345cf9d 590 log("SSH_AGENT_FAILURE");
5260325f 591 return 0;
592 case SSH_AGENT_SUCCESS:
5260325f 593 return 1;
594 default:
089fbbd2 595 fatal("Bad response from authentication agent: %d", type);
8efc0c15 596 }
5260325f 597 /* NOTREACHED */
598 return 0;
599}
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