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Commit | Line | Data |
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8efc0c15 | 1 | /* |
6ae2364d | 2 | * |
5260325f | 3 | * authfd.c |
6ae2364d | 4 | * |
5260325f | 5 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
6ae2364d | 6 | * |
5260325f | 7 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
8 | * All rights reserved | |
6ae2364d | 9 | * |
5260325f | 10 | * Created: Wed Mar 29 01:30:28 1995 ylo |
6ae2364d | 11 | * |
5260325f | 12 | * Functions for connecting the local authentication agent. |
6ae2364d | 13 | * |
5260325f | 14 | */ |
8efc0c15 | 15 | |
16 | #include "includes.h" | |
4c8722d9 | 17 | RCSID("$OpenBSD: authfd.c,v 1.22 2000/07/16 08:27:20 markus Exp $"); |
8efc0c15 | 18 | |
19 | #include "ssh.h" | |
20 | #include "rsa.h" | |
8efc0c15 | 21 | #include "buffer.h" |
22 | #include "bufaux.h" | |
23 | #include "xmalloc.h" | |
24 | #include "getput.h" | |
25 | ||
26 | #include <openssl/rsa.h> | |
4c8722d9 | 27 | #include <openssl/dsa.h> |
28 | #include <openssl/evp.h> | |
29 | #include "key.h" | |
30 | #include "authfd.h" | |
31 | #include "kex.h" | |
8efc0c15 | 32 | |
089fbbd2 | 33 | /* helper */ |
34 | int ssh_agent_get_reply(AuthenticationConnection *auth); | |
35 | ||
8efc0c15 | 36 | /* Returns the number of the authentication fd, or -1 if there is none. */ |
37 | ||
38 | int | |
39 | ssh_get_authentication_socket() | |
40 | { | |
5260325f | 41 | const char *authsocket; |
42 | int sock; | |
43 | struct sockaddr_un sunaddr; | |
44 | ||
45 | authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME); | |
46 | if (!authsocket) | |
47 | return -1; | |
48 | ||
49 | sunaddr.sun_family = AF_UNIX; | |
50 | strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path)); | |
51 | ||
52 | sock = socket(AF_UNIX, SOCK_STREAM, 0); | |
53 | if (sock < 0) | |
54 | return -1; | |
55 | ||
56 | /* close on exec */ | |
57 | if (fcntl(sock, F_SETFD, 1) == -1) { | |
58 | close(sock); | |
59 | return -1; | |
60 | } | |
61 | if (connect(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) { | |
62 | close(sock); | |
63 | return -1; | |
64 | } | |
65 | return sock; | |
8efc0c15 | 66 | } |
67 | ||
aa3378df | 68 | /* |
69 | * Closes the agent socket if it should be closed (depends on how it was | |
70 | * obtained). The argument must have been returned by | |
71 | * ssh_get_authentication_socket(). | |
72 | */ | |
8efc0c15 | 73 | |
6ae2364d | 74 | void |
5260325f | 75 | ssh_close_authentication_socket(int sock) |
8efc0c15 | 76 | { |
5260325f | 77 | if (getenv(SSH_AUTHSOCKET_ENV_NAME)) |
78 | close(sock); | |
8efc0c15 | 79 | } |
80 | ||
aa3378df | 81 | /* |
82 | * Opens and connects a private socket for communication with the | |
83 | * authentication agent. Returns the file descriptor (which must be | |
84 | * shut down and closed by the caller when no longer needed). | |
85 | * Returns NULL if an error occurred and the connection could not be | |
86 | * opened. | |
87 | */ | |
8efc0c15 | 88 | |
5260325f | 89 | AuthenticationConnection * |
90 | ssh_get_authentication_connection() | |
8efc0c15 | 91 | { |
5260325f | 92 | AuthenticationConnection *auth; |
93 | int sock; | |
94 | ||
95 | sock = ssh_get_authentication_socket(); | |
96 | ||
aa3378df | 97 | /* |
98 | * Fail if we couldn't obtain a connection. This happens if we | |
99 | * exited due to a timeout. | |
100 | */ | |
5260325f | 101 | if (sock < 0) |
102 | return NULL; | |
103 | ||
5260325f | 104 | auth = xmalloc(sizeof(*auth)); |
105 | auth->fd = sock; | |
106 | buffer_init(&auth->packet); | |
107 | buffer_init(&auth->identities); | |
108 | auth->howmany = 0; | |
109 | ||
110 | return auth; | |
8efc0c15 | 111 | } |
112 | ||
aa3378df | 113 | /* |
114 | * Closes the connection to the authentication agent and frees any associated | |
115 | * memory. | |
116 | */ | |
8efc0c15 | 117 | |
6ae2364d | 118 | void |
5260325f | 119 | ssh_close_authentication_connection(AuthenticationConnection *ac) |
8efc0c15 | 120 | { |
5260325f | 121 | buffer_free(&ac->packet); |
122 | buffer_free(&ac->identities); | |
123 | close(ac->fd); | |
124 | xfree(ac); | |
8efc0c15 | 125 | } |
126 | ||
aa3378df | 127 | /* |
128 | * Returns the first authentication identity held by the agent. | |
129 | * Returns true if an identity is available, 0 otherwise. | |
130 | * The caller must initialize the integers before the call, and free the | |
131 | * comment after a successful call (before calling ssh_get_next_identity). | |
132 | */ | |
8efc0c15 | 133 | |
134 | int | |
135 | ssh_get_first_identity(AuthenticationConnection *auth, | |
4d195447 | 136 | BIGNUM *e, BIGNUM *n, char **comment) |
8efc0c15 | 137 | { |
5260325f | 138 | unsigned char msg[8192]; |
139 | int len, l; | |
140 | ||
aa3378df | 141 | /* |
142 | * Send a message to the agent requesting for a list of the | |
143 | * identities it can represent. | |
144 | */ | |
4c8722d9 | 145 | PUT_32BIT(msg, 1); |
5260325f | 146 | msg[4] = SSH_AGENTC_REQUEST_RSA_IDENTITIES; |
a408af76 | 147 | if (atomicio(write, auth->fd, msg, 5) != 5) { |
5260325f | 148 | error("write auth->fd: %.100s", strerror(errno)); |
149 | return 0; | |
150 | } | |
151 | /* Read the length of the response. XXX implement timeouts here. */ | |
152 | len = 4; | |
153 | while (len > 0) { | |
154 | l = read(auth->fd, msg + 4 - len, len); | |
155 | if (l <= 0) { | |
156 | error("read auth->fd: %.100s", strerror(errno)); | |
157 | return 0; | |
158 | } | |
159 | len -= l; | |
160 | } | |
161 | ||
aa3378df | 162 | /* |
163 | * Extract the length, and check it for sanity. (We cannot trust | |
164 | * authentication agents). | |
165 | */ | |
5260325f | 166 | len = GET_32BIT(msg); |
167 | if (len < 1 || len > 256 * 1024) | |
168 | fatal("Authentication reply message too long: %d\n", len); | |
169 | ||
170 | /* Read the packet itself. */ | |
171 | buffer_clear(&auth->identities); | |
172 | while (len > 0) { | |
173 | l = len; | |
174 | if (l > sizeof(msg)) | |
175 | l = sizeof(msg); | |
176 | l = read(auth->fd, msg, l); | |
177 | if (l <= 0) | |
178 | fatal("Incomplete authentication reply."); | |
179 | buffer_append(&auth->identities, (char *) msg, l); | |
180 | len -= l; | |
8efc0c15 | 181 | } |
5260325f | 182 | |
183 | /* Get message type, and verify that we got a proper answer. */ | |
184 | buffer_get(&auth->identities, (char *) msg, 1); | |
185 | if (msg[0] != SSH_AGENT_RSA_IDENTITIES_ANSWER) | |
186 | fatal("Bad authentication reply message type: %d", msg[0]); | |
187 | ||
188 | /* Get the number of entries in the response and check it for sanity. */ | |
189 | auth->howmany = buffer_get_int(&auth->identities); | |
190 | if (auth->howmany > 1024) | |
191 | fatal("Too many identities in authentication reply: %d\n", auth->howmany); | |
192 | ||
193 | /* Return the first entry (if any). */ | |
194 | return ssh_get_next_identity(auth, e, n, comment); | |
8efc0c15 | 195 | } |
196 | ||
aa3378df | 197 | /* |
198 | * Returns the next authentication identity for the agent. Other functions | |
199 | * can be called between this and ssh_get_first_identity or two calls of this | |
200 | * function. This returns 0 if there are no more identities. The caller | |
201 | * must free comment after a successful return. | |
202 | */ | |
8efc0c15 | 203 | |
204 | int | |
205 | ssh_get_next_identity(AuthenticationConnection *auth, | |
4d195447 | 206 | BIGNUM *e, BIGNUM *n, char **comment) |
8efc0c15 | 207 | { |
5260325f | 208 | unsigned int bits; |
4d195447 | 209 | |
5260325f | 210 | /* Return failure if no more entries. */ |
211 | if (auth->howmany <= 0) | |
212 | return 0; | |
8efc0c15 | 213 | |
aa3378df | 214 | /* |
215 | * Get the next entry from the packet. These will abort with a fatal | |
216 | * error if the packet is too short or contains corrupt data. | |
217 | */ | |
5260325f | 218 | bits = buffer_get_int(&auth->identities); |
219 | buffer_get_bignum(&auth->identities, e); | |
220 | buffer_get_bignum(&auth->identities, n); | |
221 | *comment = buffer_get_string(&auth->identities, NULL); | |
8efc0c15 | 222 | |
5260325f | 223 | if (bits != BN_num_bits(n)) |
0b242b12 | 224 | log("Warning: identity keysize mismatch: actual %d, announced %u", |
225 | BN_num_bits(n), bits); | |
4d195447 | 226 | |
5260325f | 227 | /* Decrement the number of remaining entries. */ |
228 | auth->howmany--; | |
8efc0c15 | 229 | |
5260325f | 230 | return 1; |
8efc0c15 | 231 | } |
232 | ||
aa3378df | 233 | /* |
234 | * Generates a random challenge, sends it to the agent, and waits for | |
235 | * response from the agent. Returns true (non-zero) if the agent gave the | |
236 | * correct answer, zero otherwise. Response type selects the style of | |
237 | * response desired, with 0 corresponding to protocol version 1.0 (no longer | |
238 | * supported) and 1 corresponding to protocol version 1.1. | |
239 | */ | |
8efc0c15 | 240 | |
241 | int | |
242 | ssh_decrypt_challenge(AuthenticationConnection *auth, | |
5260325f | 243 | BIGNUM* e, BIGNUM *n, BIGNUM *challenge, |
8efc0c15 | 244 | unsigned char session_id[16], |
245 | unsigned int response_type, | |
246 | unsigned char response[16]) | |
247 | { | |
5260325f | 248 | Buffer buffer; |
249 | unsigned char buf[8192]; | |
250 | int len, l, i; | |
251 | ||
252 | /* Response type 0 is no longer supported. */ | |
253 | if (response_type == 0) | |
254 | fatal("Compatibility with ssh protocol version 1.0 no longer supported."); | |
255 | ||
256 | /* Format a message to the agent. */ | |
257 | buf[0] = SSH_AGENTC_RSA_CHALLENGE; | |
258 | buffer_init(&buffer); | |
259 | buffer_append(&buffer, (char *) buf, 1); | |
260 | buffer_put_int(&buffer, BN_num_bits(n)); | |
261 | buffer_put_bignum(&buffer, e); | |
262 | buffer_put_bignum(&buffer, n); | |
263 | buffer_put_bignum(&buffer, challenge); | |
264 | buffer_append(&buffer, (char *) session_id, 16); | |
265 | buffer_put_int(&buffer, response_type); | |
266 | ||
267 | /* Get the length of the message, and format it in the buffer. */ | |
268 | len = buffer_len(&buffer); | |
269 | PUT_32BIT(buf, len); | |
270 | ||
271 | /* Send the length and then the packet to the agent. */ | |
a408af76 | 272 | if (atomicio(write, auth->fd, buf, 4) != 4 || |
273 | atomicio(write, auth->fd, buffer_ptr(&buffer), | |
274 | buffer_len(&buffer)) != buffer_len(&buffer)) { | |
5260325f | 275 | error("Error writing to authentication socket."); |
276 | error_cleanup: | |
277 | buffer_free(&buffer); | |
278 | return 0; | |
279 | } | |
aa3378df | 280 | /* |
281 | * Wait for response from the agent. First read the length of the | |
282 | * response packet. | |
283 | */ | |
5260325f | 284 | len = 4; |
285 | while (len > 0) { | |
286 | l = read(auth->fd, buf + 4 - len, len); | |
287 | if (l <= 0) { | |
288 | error("Error reading response length from authentication socket."); | |
289 | goto error_cleanup; | |
290 | } | |
291 | len -= l; | |
292 | } | |
293 | ||
294 | /* Extract the length, and check it for sanity. */ | |
295 | len = GET_32BIT(buf); | |
296 | if (len > 256 * 1024) | |
297 | fatal("Authentication response too long: %d", len); | |
298 | ||
299 | /* Read the rest of the response in tothe buffer. */ | |
300 | buffer_clear(&buffer); | |
301 | while (len > 0) { | |
302 | l = len; | |
303 | if (l > sizeof(buf)) | |
304 | l = sizeof(buf); | |
305 | l = read(auth->fd, buf, l); | |
306 | if (l <= 0) { | |
307 | error("Error reading response from authentication socket."); | |
308 | goto error_cleanup; | |
309 | } | |
310 | buffer_append(&buffer, (char *) buf, l); | |
311 | len -= l; | |
8efc0c15 | 312 | } |
5260325f | 313 | |
314 | /* Get the type of the packet. */ | |
315 | buffer_get(&buffer, (char *) buf, 1); | |
316 | ||
317 | /* Check for agent failure message. */ | |
318 | if (buf[0] == SSH_AGENT_FAILURE) { | |
319 | log("Agent admitted failure to authenticate using the key."); | |
320 | goto error_cleanup; | |
8efc0c15 | 321 | } |
5260325f | 322 | /* Now it must be an authentication response packet. */ |
323 | if (buf[0] != SSH_AGENT_RSA_RESPONSE) | |
324 | fatal("Bad authentication response: %d", buf[0]); | |
325 | ||
aa3378df | 326 | /* |
327 | * Get the response from the packet. This will abort with a fatal | |
328 | * error if the packet is corrupt. | |
329 | */ | |
5260325f | 330 | for (i = 0; i < 16; i++) |
331 | response[i] = buffer_get_char(&buffer); | |
332 | ||
333 | /* The buffer containing the packet is no longer needed. */ | |
334 | buffer_free(&buffer); | |
335 | ||
336 | /* Correct answer. */ | |
337 | return 1; | |
338 | } | |
8efc0c15 | 339 | |
4c8722d9 | 340 | /* Encode key for a message to the agent. */ |
341 | ||
342 | void | |
343 | ssh_encode_identity_rsa(Buffer *b, RSA *key, const char *comment) | |
344 | { | |
345 | buffer_clear(b); | |
346 | buffer_put_char(b, SSH_AGENTC_ADD_RSA_IDENTITY); | |
347 | buffer_put_int(b, BN_num_bits(key->n)); | |
348 | buffer_put_bignum(b, key->n); | |
349 | buffer_put_bignum(b, key->e); | |
350 | buffer_put_bignum(b, key->d); | |
351 | /* To keep within the protocol: p < q for ssh. in SSL p > q */ | |
352 | buffer_put_bignum(b, key->iqmp); /* ssh key->u */ | |
353 | buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */ | |
354 | buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */ | |
355 | buffer_put_string(b, comment, strlen(comment)); | |
356 | } | |
357 | ||
358 | void | |
359 | ssh_encode_identity_dsa(Buffer *b, DSA *key, const char *comment) | |
360 | { | |
361 | buffer_clear(b); | |
362 | buffer_put_char(b, SSH2_AGENTC_ADD_IDENTITY); | |
363 | buffer_put_cstring(b, KEX_DSS); | |
364 | buffer_put_bignum2(b, key->p); | |
365 | buffer_put_bignum2(b, key->q); | |
366 | buffer_put_bignum2(b, key->g); | |
367 | buffer_put_bignum2(b, key->pub_key); | |
368 | buffer_put_bignum2(b, key->priv_key); | |
369 | buffer_put_string(b, comment, strlen(comment)); | |
370 | } | |
371 | ||
aa3378df | 372 | /* |
373 | * Adds an identity to the authentication server. This call is not meant to | |
374 | * be used by normal applications. | |
375 | */ | |
8efc0c15 | 376 | |
6ae2364d | 377 | int |
4c8722d9 | 378 | ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment) |
8efc0c15 | 379 | { |
5260325f | 380 | Buffer buffer; |
381 | unsigned char buf[8192]; | |
089fbbd2 | 382 | int len; |
5260325f | 383 | |
5260325f | 384 | buffer_init(&buffer); |
4c8722d9 | 385 | |
386 | switch (key->type) { | |
387 | case KEY_RSA: | |
388 | ssh_encode_identity_rsa(&buffer, key->rsa, comment); | |
389 | break; | |
390 | case KEY_DSA: | |
391 | ssh_encode_identity_dsa(&buffer, key->dsa, comment); | |
392 | break; | |
393 | default: | |
394 | buffer_free(&buffer); | |
395 | return 0; | |
396 | break; | |
397 | } | |
5260325f | 398 | |
399 | /* Get the length of the message, and format it in the buffer. */ | |
400 | len = buffer_len(&buffer); | |
401 | PUT_32BIT(buf, len); | |
402 | ||
403 | /* Send the length and then the packet to the agent. */ | |
a408af76 | 404 | if (atomicio(write, auth->fd, buf, 4) != 4 || |
405 | atomicio(write, auth->fd, buffer_ptr(&buffer), | |
406 | buffer_len(&buffer)) != buffer_len(&buffer)) { | |
5260325f | 407 | error("Error writing to authentication socket."); |
5260325f | 408 | buffer_free(&buffer); |
409 | return 0; | |
410 | } | |
089fbbd2 | 411 | buffer_free(&buffer); |
412 | return ssh_agent_get_reply(auth); | |
5260325f | 413 | } |
414 | ||
aa3378df | 415 | /* |
416 | * Removes an identity from the authentication server. This call is not | |
417 | * meant to be used by normal applications. | |
418 | */ | |
8efc0c15 | 419 | |
6ae2364d | 420 | int |
5260325f | 421 | ssh_remove_identity(AuthenticationConnection *auth, RSA *key) |
8efc0c15 | 422 | { |
5260325f | 423 | Buffer buffer; |
089fbbd2 | 424 | unsigned char buf[5]; |
425 | int len; | |
5260325f | 426 | |
427 | /* Format a message to the agent. */ | |
428 | buffer_init(&buffer); | |
429 | buffer_put_char(&buffer, SSH_AGENTC_REMOVE_RSA_IDENTITY); | |
430 | buffer_put_int(&buffer, BN_num_bits(key->n)); | |
431 | buffer_put_bignum(&buffer, key->e); | |
432 | buffer_put_bignum(&buffer, key->n); | |
433 | ||
434 | /* Get the length of the message, and format it in the buffer. */ | |
435 | len = buffer_len(&buffer); | |
436 | PUT_32BIT(buf, len); | |
437 | ||
438 | /* Send the length and then the packet to the agent. */ | |
a408af76 | 439 | if (atomicio(write, auth->fd, buf, 4) != 4 || |
440 | atomicio(write, auth->fd, buffer_ptr(&buffer), | |
441 | buffer_len(&buffer)) != buffer_len(&buffer)) { | |
5260325f | 442 | error("Error writing to authentication socket."); |
5260325f | 443 | buffer_free(&buffer); |
444 | return 0; | |
445 | } | |
089fbbd2 | 446 | buffer_free(&buffer); |
447 | return ssh_agent_get_reply(auth); | |
5260325f | 448 | } |
449 | ||
aa3378df | 450 | /* |
451 | * Removes all identities from the agent. This call is not meant to be used | |
452 | * by normal applications. | |
453 | */ | |
8efc0c15 | 454 | |
6ae2364d | 455 | int |
5260325f | 456 | ssh_remove_all_identities(AuthenticationConnection *auth) |
8efc0c15 | 457 | { |
089fbbd2 | 458 | unsigned char buf[5]; |
5260325f | 459 | |
460 | /* Get the length of the message, and format it in the buffer. */ | |
461 | PUT_32BIT(buf, 1); | |
462 | buf[4] = SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES; | |
463 | ||
464 | /* Send the length and then the packet to the agent. */ | |
a408af76 | 465 | if (atomicio(write, auth->fd, buf, 5) != 5) { |
5260325f | 466 | error("Error writing to authentication socket."); |
467 | return 0; | |
468 | } | |
089fbbd2 | 469 | return ssh_agent_get_reply(auth); |
470 | } | |
471 | ||
472 | /* | |
473 | * Read for reply from agent. returns 1 for success, 0 on error | |
474 | */ | |
475 | ||
476 | int | |
477 | ssh_agent_get_reply(AuthenticationConnection *auth) | |
478 | { | |
479 | Buffer buffer; | |
480 | unsigned char buf[8192]; | |
481 | int len, l, type; | |
482 | ||
aa3378df | 483 | /* |
484 | * Wait for response from the agent. First read the length of the | |
485 | * response packet. | |
486 | */ | |
5260325f | 487 | len = 4; |
488 | while (len > 0) { | |
489 | l = read(auth->fd, buf + 4 - len, len); | |
490 | if (l <= 0) { | |
491 | error("Error reading response length from authentication socket."); | |
089fbbd2 | 492 | buffer_free(&buffer); |
5260325f | 493 | return 0; |
494 | } | |
495 | len -= l; | |
496 | } | |
497 | ||
498 | /* Extract the length, and check it for sanity. */ | |
499 | len = GET_32BIT(buf); | |
500 | if (len > 256 * 1024) | |
089fbbd2 | 501 | fatal("Response from agent too long: %d", len); |
5260325f | 502 | |
089fbbd2 | 503 | /* Read the rest of the response in to the buffer. */ |
5260325f | 504 | buffer_init(&buffer); |
505 | while (len > 0) { | |
506 | l = len; | |
507 | if (l > sizeof(buf)) | |
508 | l = sizeof(buf); | |
509 | l = read(auth->fd, buf, l); | |
510 | if (l <= 0) { | |
511 | error("Error reading response from authentication socket."); | |
512 | buffer_free(&buffer); | |
513 | return 0; | |
514 | } | |
515 | buffer_append(&buffer, (char *) buf, l); | |
516 | len -= l; | |
8efc0c15 | 517 | } |
5260325f | 518 | |
519 | /* Get the type of the packet. */ | |
520 | type = buffer_get_char(&buffer); | |
089fbbd2 | 521 | buffer_free(&buffer); |
5260325f | 522 | switch (type) { |
523 | case SSH_AGENT_FAILURE: | |
4c8722d9 | 524 | log("SSH_AGENT_FAILURE"); |
5260325f | 525 | return 0; |
526 | case SSH_AGENT_SUCCESS: | |
5260325f | 527 | return 1; |
528 | default: | |
089fbbd2 | 529 | fatal("Bad response from authentication agent: %d", type); |
8efc0c15 | 530 | } |
5260325f | 531 | /* NOTREACHED */ |
532 | return 0; | |
533 | } |