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1 | /* | |
2 | * | |
3 | * authfd.c | |
4 | * | |
5 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
6 | * | |
7 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
8 | * All rights reserved | |
9 | * | |
10 | * Created: Wed Mar 29 01:30:28 1995 ylo | |
11 | * | |
12 | * Functions for connecting the local authentication agent. | |
13 | * | |
14 | */ | |
15 | ||
16 | #include "includes.h" | |
17 | RCSID("$Id$"); | |
18 | ||
19 | #include "ssh.h" | |
20 | #include "rsa.h" | |
21 | #include "authfd.h" | |
22 | #include "buffer.h" | |
23 | #include "bufaux.h" | |
24 | #include "xmalloc.h" | |
25 | #include "getput.h" | |
26 | ||
27 | #ifdef HAVE_OPENSSL | |
28 | #include <openssl/rsa.h> | |
29 | #endif | |
30 | #ifdef HAVE_SSL | |
31 | #include <ssl/rsa.h> | |
32 | #endif | |
33 | ||
34 | /* Returns the number of the authentication fd, or -1 if there is none. */ | |
35 | ||
36 | int | |
37 | ssh_get_authentication_socket() | |
38 | { | |
39 | const char *authsocket; | |
40 | int sock; | |
41 | struct sockaddr_un sunaddr; | |
42 | ||
43 | authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME); | |
44 | if (!authsocket) | |
45 | return -1; | |
46 | ||
47 | sunaddr.sun_family = AF_UNIX; | |
48 | strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path)); | |
49 | ||
50 | sock = socket(AF_UNIX, SOCK_STREAM, 0); | |
51 | if (sock < 0) | |
52 | return -1; | |
53 | ||
54 | /* close on exec */ | |
55 | if (fcntl(sock, F_SETFD, 1) == -1) { | |
56 | close(sock); | |
57 | return -1; | |
58 | } | |
59 | if (connect(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) { | |
60 | close(sock); | |
61 | return -1; | |
62 | } | |
63 | return sock; | |
64 | } | |
65 | ||
66 | /* | |
67 | * Closes the agent socket if it should be closed (depends on how it was | |
68 | * obtained). The argument must have been returned by | |
69 | * ssh_get_authentication_socket(). | |
70 | */ | |
71 | ||
72 | void | |
73 | ssh_close_authentication_socket(int sock) | |
74 | { | |
75 | if (getenv(SSH_AUTHSOCKET_ENV_NAME)) | |
76 | close(sock); | |
77 | } | |
78 | ||
79 | /* | |
80 | * Opens and connects a private socket for communication with the | |
81 | * authentication agent. Returns the file descriptor (which must be | |
82 | * shut down and closed by the caller when no longer needed). | |
83 | * Returns NULL if an error occurred and the connection could not be | |
84 | * opened. | |
85 | */ | |
86 | ||
87 | AuthenticationConnection * | |
88 | ssh_get_authentication_connection() | |
89 | { | |
90 | AuthenticationConnection *auth; | |
91 | int sock; | |
92 | ||
93 | sock = ssh_get_authentication_socket(); | |
94 | ||
95 | /* | |
96 | * Fail if we couldn't obtain a connection. This happens if we | |
97 | * exited due to a timeout. | |
98 | */ | |
99 | if (sock < 0) | |
100 | return NULL; | |
101 | ||
102 | auth = xmalloc(sizeof(*auth)); | |
103 | auth->fd = sock; | |
104 | buffer_init(&auth->packet); | |
105 | buffer_init(&auth->identities); | |
106 | auth->howmany = 0; | |
107 | ||
108 | return auth; | |
109 | } | |
110 | ||
111 | /* | |
112 | * Closes the connection to the authentication agent and frees any associated | |
113 | * memory. | |
114 | */ | |
115 | ||
116 | void | |
117 | ssh_close_authentication_connection(AuthenticationConnection *ac) | |
118 | { | |
119 | buffer_free(&ac->packet); | |
120 | buffer_free(&ac->identities); | |
121 | close(ac->fd); | |
122 | xfree(ac); | |
123 | } | |
124 | ||
125 | /* | |
126 | * Returns the first authentication identity held by the agent. | |
127 | * Returns true if an identity is available, 0 otherwise. | |
128 | * The caller must initialize the integers before the call, and free the | |
129 | * comment after a successful call (before calling ssh_get_next_identity). | |
130 | */ | |
131 | ||
132 | int | |
133 | ssh_get_first_identity(AuthenticationConnection *auth, | |
134 | BIGNUM *e, BIGNUM *n, char **comment) | |
135 | { | |
136 | unsigned char msg[8192]; | |
137 | int len, l; | |
138 | ||
139 | /* | |
140 | * Send a message to the agent requesting for a list of the | |
141 | * identities it can represent. | |
142 | */ | |
143 | msg[0] = 0; | |
144 | msg[1] = 0; | |
145 | msg[2] = 0; | |
146 | msg[3] = 1; | |
147 | msg[4] = SSH_AGENTC_REQUEST_RSA_IDENTITIES; | |
148 | if (write(auth->fd, msg, 5) != 5) { | |
149 | error("write auth->fd: %.100s", strerror(errno)); | |
150 | return 0; | |
151 | } | |
152 | /* Read the length of the response. XXX implement timeouts here. */ | |
153 | len = 4; | |
154 | while (len > 0) { | |
155 | l = read(auth->fd, msg + 4 - len, len); | |
156 | if (l <= 0) { | |
157 | error("read auth->fd: %.100s", strerror(errno)); | |
158 | return 0; | |
159 | } | |
160 | len -= l; | |
161 | } | |
162 | ||
163 | /* | |
164 | * Extract the length, and check it for sanity. (We cannot trust | |
165 | * authentication agents). | |
166 | */ | |
167 | len = GET_32BIT(msg); | |
168 | if (len < 1 || len > 256 * 1024) | |
169 | fatal("Authentication reply message too long: %d\n", len); | |
170 | ||
171 | /* Read the packet itself. */ | |
172 | buffer_clear(&auth->identities); | |
173 | while (len > 0) { | |
174 | l = len; | |
175 | if (l > sizeof(msg)) | |
176 | l = sizeof(msg); | |
177 | l = read(auth->fd, msg, l); | |
178 | if (l <= 0) | |
179 | fatal("Incomplete authentication reply."); | |
180 | buffer_append(&auth->identities, (char *) msg, l); | |
181 | len -= l; | |
182 | } | |
183 | ||
184 | /* Get message type, and verify that we got a proper answer. */ | |
185 | buffer_get(&auth->identities, (char *) msg, 1); | |
186 | if (msg[0] != SSH_AGENT_RSA_IDENTITIES_ANSWER) | |
187 | fatal("Bad authentication reply message type: %d", msg[0]); | |
188 | ||
189 | /* Get the number of entries in the response and check it for sanity. */ | |
190 | auth->howmany = buffer_get_int(&auth->identities); | |
191 | if (auth->howmany > 1024) | |
192 | fatal("Too many identities in authentication reply: %d\n", auth->howmany); | |
193 | ||
194 | /* Return the first entry (if any). */ | |
195 | return ssh_get_next_identity(auth, e, n, comment); | |
196 | } | |
197 | ||
198 | /* | |
199 | * Returns the next authentication identity for the agent. Other functions | |
200 | * can be called between this and ssh_get_first_identity or two calls of this | |
201 | * function. This returns 0 if there are no more identities. The caller | |
202 | * must free comment after a successful return. | |
203 | */ | |
204 | ||
205 | int | |
206 | ssh_get_next_identity(AuthenticationConnection *auth, | |
207 | BIGNUM *e, BIGNUM *n, char **comment) | |
208 | { | |
209 | unsigned int bits; | |
210 | ||
211 | /* Return failure if no more entries. */ | |
212 | if (auth->howmany <= 0) | |
213 | return 0; | |
214 | ||
215 | /* | |
216 | * Get the next entry from the packet. These will abort with a fatal | |
217 | * error if the packet is too short or contains corrupt data. | |
218 | */ | |
219 | bits = buffer_get_int(&auth->identities); | |
220 | buffer_get_bignum(&auth->identities, e); | |
221 | buffer_get_bignum(&auth->identities, n); | |
222 | *comment = buffer_get_string(&auth->identities, NULL); | |
223 | ||
224 | if (bits != BN_num_bits(n)) | |
225 | error("Warning: keysize mismatch: actual %d, announced %u", | |
226 | BN_num_bits(n), bits); | |
227 | ||
228 | /* Decrement the number of remaining entries. */ | |
229 | auth->howmany--; | |
230 | ||
231 | return 1; | |
232 | } | |
233 | ||
234 | /* | |
235 | * Generates a random challenge, sends it to the agent, and waits for | |
236 | * response from the agent. Returns true (non-zero) if the agent gave the | |
237 | * correct answer, zero otherwise. Response type selects the style of | |
238 | * response desired, with 0 corresponding to protocol version 1.0 (no longer | |
239 | * supported) and 1 corresponding to protocol version 1.1. | |
240 | */ | |
241 | ||
242 | int | |
243 | ssh_decrypt_challenge(AuthenticationConnection *auth, | |
244 | BIGNUM* e, BIGNUM *n, BIGNUM *challenge, | |
245 | unsigned char session_id[16], | |
246 | unsigned int response_type, | |
247 | unsigned char response[16]) | |
248 | { | |
249 | Buffer buffer; | |
250 | unsigned char buf[8192]; | |
251 | int len, l, i; | |
252 | ||
253 | /* Response type 0 is no longer supported. */ | |
254 | if (response_type == 0) | |
255 | fatal("Compatibility with ssh protocol version 1.0 no longer supported."); | |
256 | ||
257 | /* Format a message to the agent. */ | |
258 | buf[0] = SSH_AGENTC_RSA_CHALLENGE; | |
259 | buffer_init(&buffer); | |
260 | buffer_append(&buffer, (char *) buf, 1); | |
261 | buffer_put_int(&buffer, BN_num_bits(n)); | |
262 | buffer_put_bignum(&buffer, e); | |
263 | buffer_put_bignum(&buffer, n); | |
264 | buffer_put_bignum(&buffer, challenge); | |
265 | buffer_append(&buffer, (char *) session_id, 16); | |
266 | buffer_put_int(&buffer, response_type); | |
267 | ||
268 | /* Get the length of the message, and format it in the buffer. */ | |
269 | len = buffer_len(&buffer); | |
270 | PUT_32BIT(buf, len); | |
271 | ||
272 | /* Send the length and then the packet to the agent. */ | |
273 | if (write(auth->fd, buf, 4) != 4 || | |
274 | write(auth->fd, buffer_ptr(&buffer), buffer_len(&buffer)) != | |
275 | buffer_len(&buffer)) { | |
276 | error("Error writing to authentication socket."); | |
277 | error_cleanup: | |
278 | buffer_free(&buffer); | |
279 | return 0; | |
280 | } | |
281 | /* | |
282 | * Wait for response from the agent. First read the length of the | |
283 | * response packet. | |
284 | */ | |
285 | len = 4; | |
286 | while (len > 0) { | |
287 | l = read(auth->fd, buf + 4 - len, len); | |
288 | if (l <= 0) { | |
289 | error("Error reading response length from authentication socket."); | |
290 | goto error_cleanup; | |
291 | } | |
292 | len -= l; | |
293 | } | |
294 | ||
295 | /* Extract the length, and check it for sanity. */ | |
296 | len = GET_32BIT(buf); | |
297 | if (len > 256 * 1024) | |
298 | fatal("Authentication response too long: %d", len); | |
299 | ||
300 | /* Read the rest of the response in tothe buffer. */ | |
301 | buffer_clear(&buffer); | |
302 | while (len > 0) { | |
303 | l = len; | |
304 | if (l > sizeof(buf)) | |
305 | l = sizeof(buf); | |
306 | l = read(auth->fd, buf, l); | |
307 | if (l <= 0) { | |
308 | error("Error reading response from authentication socket."); | |
309 | goto error_cleanup; | |
310 | } | |
311 | buffer_append(&buffer, (char *) buf, l); | |
312 | len -= l; | |
313 | } | |
314 | ||
315 | /* Get the type of the packet. */ | |
316 | buffer_get(&buffer, (char *) buf, 1); | |
317 | ||
318 | /* Check for agent failure message. */ | |
319 | if (buf[0] == SSH_AGENT_FAILURE) { | |
320 | log("Agent admitted failure to authenticate using the key."); | |
321 | goto error_cleanup; | |
322 | } | |
323 | /* Now it must be an authentication response packet. */ | |
324 | if (buf[0] != SSH_AGENT_RSA_RESPONSE) | |
325 | fatal("Bad authentication response: %d", buf[0]); | |
326 | ||
327 | /* | |
328 | * Get the response from the packet. This will abort with a fatal | |
329 | * error if the packet is corrupt. | |
330 | */ | |
331 | for (i = 0; i < 16; i++) | |
332 | response[i] = buffer_get_char(&buffer); | |
333 | ||
334 | /* The buffer containing the packet is no longer needed. */ | |
335 | buffer_free(&buffer); | |
336 | ||
337 | /* Correct answer. */ | |
338 | return 1; | |
339 | } | |
340 | ||
341 | /* | |
342 | * Adds an identity to the authentication server. This call is not meant to | |
343 | * be used by normal applications. | |
344 | */ | |
345 | ||
346 | int | |
347 | ssh_add_identity(AuthenticationConnection *auth, | |
348 | RSA * key, const char *comment) | |
349 | { | |
350 | Buffer buffer; | |
351 | unsigned char buf[8192]; | |
352 | int len, l, type; | |
353 | ||
354 | /* Format a message to the agent. */ | |
355 | buffer_init(&buffer); | |
356 | buffer_put_char(&buffer, SSH_AGENTC_ADD_RSA_IDENTITY); | |
357 | buffer_put_int(&buffer, BN_num_bits(key->n)); | |
358 | buffer_put_bignum(&buffer, key->n); | |
359 | buffer_put_bignum(&buffer, key->e); | |
360 | buffer_put_bignum(&buffer, key->d); | |
361 | /* To keep within the protocol: p < q for ssh. in SSL p > q */ | |
362 | buffer_put_bignum(&buffer, key->iqmp); /* ssh key->u */ | |
363 | buffer_put_bignum(&buffer, key->q); /* ssh key->p, SSL key->q */ | |
364 | buffer_put_bignum(&buffer, key->p); /* ssh key->q, SSL key->p */ | |
365 | buffer_put_string(&buffer, comment, strlen(comment)); | |
366 | ||
367 | /* Get the length of the message, and format it in the buffer. */ | |
368 | len = buffer_len(&buffer); | |
369 | PUT_32BIT(buf, len); | |
370 | ||
371 | /* Send the length and then the packet to the agent. */ | |
372 | if (write(auth->fd, buf, 4) != 4 || | |
373 | write(auth->fd, buffer_ptr(&buffer), buffer_len(&buffer)) != | |
374 | buffer_len(&buffer)) { | |
375 | error("Error writing to authentication socket."); | |
376 | error_cleanup: | |
377 | buffer_free(&buffer); | |
378 | return 0; | |
379 | } | |
380 | /* Wait for response from the agent. First read the length of the | |
381 | response packet. */ | |
382 | len = 4; | |
383 | while (len > 0) { | |
384 | l = read(auth->fd, buf + 4 - len, len); | |
385 | if (l <= 0) { | |
386 | error("Error reading response length from authentication socket."); | |
387 | goto error_cleanup; | |
388 | } | |
389 | len -= l; | |
390 | } | |
391 | ||
392 | /* Extract the length, and check it for sanity. */ | |
393 | len = GET_32BIT(buf); | |
394 | if (len > 256 * 1024) | |
395 | fatal("Add identity response too long: %d", len); | |
396 | ||
397 | /* Read the rest of the response in tothe buffer. */ | |
398 | buffer_clear(&buffer); | |
399 | while (len > 0) { | |
400 | l = len; | |
401 | if (l > sizeof(buf)) | |
402 | l = sizeof(buf); | |
403 | l = read(auth->fd, buf, l); | |
404 | if (l <= 0) { | |
405 | error("Error reading response from authentication socket."); | |
406 | goto error_cleanup; | |
407 | } | |
408 | buffer_append(&buffer, (char *) buf, l); | |
409 | len -= l; | |
410 | } | |
411 | ||
412 | /* Get the type of the packet. */ | |
413 | type = buffer_get_char(&buffer); | |
414 | switch (type) { | |
415 | case SSH_AGENT_FAILURE: | |
416 | buffer_free(&buffer); | |
417 | return 0; | |
418 | case SSH_AGENT_SUCCESS: | |
419 | buffer_free(&buffer); | |
420 | return 1; | |
421 | default: | |
422 | fatal("Bad response to add identity from authentication agent: %d", | |
423 | type); | |
424 | } | |
425 | /* NOTREACHED */ | |
426 | return 0; | |
427 | } | |
428 | ||
429 | /* | |
430 | * Removes an identity from the authentication server. This call is not | |
431 | * meant to be used by normal applications. | |
432 | */ | |
433 | ||
434 | int | |
435 | ssh_remove_identity(AuthenticationConnection *auth, RSA *key) | |
436 | { | |
437 | Buffer buffer; | |
438 | unsigned char buf[8192]; | |
439 | int len, l, type; | |
440 | ||
441 | /* Format a message to the agent. */ | |
442 | buffer_init(&buffer); | |
443 | buffer_put_char(&buffer, SSH_AGENTC_REMOVE_RSA_IDENTITY); | |
444 | buffer_put_int(&buffer, BN_num_bits(key->n)); | |
445 | buffer_put_bignum(&buffer, key->e); | |
446 | buffer_put_bignum(&buffer, key->n); | |
447 | ||
448 | /* Get the length of the message, and format it in the buffer. */ | |
449 | len = buffer_len(&buffer); | |
450 | PUT_32BIT(buf, len); | |
451 | ||
452 | /* Send the length and then the packet to the agent. */ | |
453 | if (write(auth->fd, buf, 4) != 4 || | |
454 | write(auth->fd, buffer_ptr(&buffer), buffer_len(&buffer)) != | |
455 | buffer_len(&buffer)) { | |
456 | error("Error writing to authentication socket."); | |
457 | error_cleanup: | |
458 | buffer_free(&buffer); | |
459 | return 0; | |
460 | } | |
461 | /* | |
462 | * Wait for response from the agent. First read the length of the | |
463 | * response packet. | |
464 | */ | |
465 | len = 4; | |
466 | while (len > 0) { | |
467 | l = read(auth->fd, buf + 4 - len, len); | |
468 | if (l <= 0) { | |
469 | error("Error reading response length from authentication socket."); | |
470 | goto error_cleanup; | |
471 | } | |
472 | len -= l; | |
473 | } | |
474 | ||
475 | /* Extract the length, and check it for sanity. */ | |
476 | len = GET_32BIT(buf); | |
477 | if (len > 256 * 1024) | |
478 | fatal("Remove identity response too long: %d", len); | |
479 | ||
480 | /* Read the rest of the response in tothe buffer. */ | |
481 | buffer_clear(&buffer); | |
482 | while (len > 0) { | |
483 | l = len; | |
484 | if (l > sizeof(buf)) | |
485 | l = sizeof(buf); | |
486 | l = read(auth->fd, buf, l); | |
487 | if (l <= 0) { | |
488 | error("Error reading response from authentication socket."); | |
489 | goto error_cleanup; | |
490 | } | |
491 | buffer_append(&buffer, (char *) buf, l); | |
492 | len -= l; | |
493 | } | |
494 | ||
495 | /* Get the type of the packet. */ | |
496 | type = buffer_get_char(&buffer); | |
497 | switch (type) { | |
498 | case SSH_AGENT_FAILURE: | |
499 | buffer_free(&buffer); | |
500 | return 0; | |
501 | case SSH_AGENT_SUCCESS: | |
502 | buffer_free(&buffer); | |
503 | return 1; | |
504 | default: | |
505 | fatal("Bad response to remove identity from authentication agent: %d", | |
506 | type); | |
507 | } | |
508 | /* NOTREACHED */ | |
509 | return 0; | |
510 | } | |
511 | ||
512 | /* | |
513 | * Removes all identities from the agent. This call is not meant to be used | |
514 | * by normal applications. | |
515 | */ | |
516 | ||
517 | int | |
518 | ssh_remove_all_identities(AuthenticationConnection *auth) | |
519 | { | |
520 | Buffer buffer; | |
521 | unsigned char buf[8192]; | |
522 | int len, l, type; | |
523 | ||
524 | /* Get the length of the message, and format it in the buffer. */ | |
525 | PUT_32BIT(buf, 1); | |
526 | buf[4] = SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES; | |
527 | ||
528 | /* Send the length and then the packet to the agent. */ | |
529 | if (write(auth->fd, buf, 5) != 5) { | |
530 | error("Error writing to authentication socket."); | |
531 | return 0; | |
532 | } | |
533 | /* | |
534 | * Wait for response from the agent. First read the length of the | |
535 | * response packet. | |
536 | */ | |
537 | len = 4; | |
538 | while (len > 0) { | |
539 | l = read(auth->fd, buf + 4 - len, len); | |
540 | if (l <= 0) { | |
541 | error("Error reading response length from authentication socket."); | |
542 | return 0; | |
543 | } | |
544 | len -= l; | |
545 | } | |
546 | ||
547 | /* Extract the length, and check it for sanity. */ | |
548 | len = GET_32BIT(buf); | |
549 | if (len > 256 * 1024) | |
550 | fatal("Remove identity response too long: %d", len); | |
551 | ||
552 | /* Read the rest of the response into the buffer. */ | |
553 | buffer_init(&buffer); | |
554 | while (len > 0) { | |
555 | l = len; | |
556 | if (l > sizeof(buf)) | |
557 | l = sizeof(buf); | |
558 | l = read(auth->fd, buf, l); | |
559 | if (l <= 0) { | |
560 | error("Error reading response from authentication socket."); | |
561 | buffer_free(&buffer); | |
562 | return 0; | |
563 | } | |
564 | buffer_append(&buffer, (char *) buf, l); | |
565 | len -= l; | |
566 | } | |
567 | ||
568 | /* Get the type of the packet. */ | |
569 | type = buffer_get_char(&buffer); | |
570 | switch (type) { | |
571 | case SSH_AGENT_FAILURE: | |
572 | buffer_free(&buffer); | |
573 | return 0; | |
574 | case SSH_AGENT_SUCCESS: | |
575 | buffer_free(&buffer); | |
576 | return 1; | |
577 | default: | |
578 | fatal("Bad response to remove identity from authentication agent: %d", | |
579 | type); | |
580 | } | |
581 | /* NOTREACHED */ | |
582 | return 0; | |
583 | } |