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8efc0c15 | 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 | #include <openssl/rsa.h> | |
28 | ||
29 | /* Returns the number of the authentication fd, or -1 if there is none. */ | |
30 | ||
31 | int | |
32 | ssh_get_authentication_socket() | |
33 | { | |
34 | const char *authsocket; | |
35 | int sock; | |
36 | struct sockaddr_un sunaddr; | |
37 | ||
38 | authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME); | |
39 | if (!authsocket) | |
40 | return -1; | |
41 | ||
42 | sunaddr.sun_family = AF_UNIX; | |
43 | strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path)); | |
44 | ||
45 | sock = socket(AF_UNIX, SOCK_STREAM, 0); | |
46 | if (sock < 0) | |
47 | return -1; | |
48 | ||
49 | if (connect(sock, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) < 0) | |
50 | { | |
51 | close(sock); | |
52 | return -1; | |
53 | } | |
54 | ||
55 | return sock; | |
56 | } | |
57 | ||
58 | /* Closes the agent socket if it should be closed (depends on how it was | |
59 | obtained). The argument must have been returned by | |
60 | ssh_get_authentication_socket(). */ | |
61 | ||
62 | void ssh_close_authentication_socket(int sock) | |
63 | { | |
64 | if (getenv(SSH_AUTHSOCKET_ENV_NAME)) | |
65 | close(sock); | |
66 | } | |
67 | ||
68 | /* Opens and connects a private socket for communication with the | |
69 | authentication agent. Returns the file descriptor (which must be | |
70 | shut down and closed by the caller when no longer needed). | |
71 | Returns NULL if an error occurred and the connection could not be | |
72 | opened. */ | |
73 | ||
74 | AuthenticationConnection *ssh_get_authentication_connection() | |
75 | { | |
76 | AuthenticationConnection *auth; | |
77 | int sock; | |
78 | ||
79 | sock = ssh_get_authentication_socket(); | |
80 | ||
81 | /* Fail if we couldn't obtain a connection. This happens if we exited | |
82 | due to a timeout. */ | |
83 | if (sock < 0) | |
84 | return NULL; | |
85 | ||
86 | /* Applocate the connection structure and initialize it. */ | |
87 | auth = xmalloc(sizeof(*auth)); | |
88 | auth->fd = sock; | |
89 | buffer_init(&auth->packet); | |
90 | buffer_init(&auth->identities); | |
91 | auth->howmany = 0; | |
92 | ||
93 | return auth; | |
94 | } | |
95 | ||
96 | /* Closes the connection to the authentication agent and frees any associated | |
97 | memory. */ | |
98 | ||
99 | void ssh_close_authentication_connection(AuthenticationConnection *ac) | |
100 | { | |
101 | buffer_free(&ac->packet); | |
102 | buffer_free(&ac->identities); | |
103 | close(ac->fd); | |
104 | /* Free the connection data structure. */ | |
105 | xfree(ac); | |
106 | } | |
107 | ||
108 | /* Returns the first authentication identity held by the agent. | |
109 | Returns true if an identity is available, 0 otherwise. | |
110 | The caller must initialize the integers before the call, and free the | |
111 | comment after a successful call (before calling ssh_get_next_identity). */ | |
112 | ||
113 | int | |
114 | ssh_get_first_identity(AuthenticationConnection *auth, | |
115 | int *bitsp, BIGNUM *e, BIGNUM *n, char **comment) | |
116 | { | |
117 | unsigned char msg[8192]; | |
118 | int len, l; | |
119 | ||
120 | /* Send a message to the agent requesting for a list of the identities | |
121 | it can represent. */ | |
122 | msg[0] = 0; | |
123 | msg[1] = 0; | |
124 | msg[2] = 0; | |
125 | msg[3] = 1; | |
126 | msg[4] = SSH_AGENTC_REQUEST_RSA_IDENTITIES; | |
127 | if (write(auth->fd, msg, 5) != 5) | |
128 | { | |
129 | error("write auth->fd: %.100s", strerror(errno)); | |
130 | return 0; | |
131 | } | |
132 | ||
133 | /* Read the length of the response. XXX implement timeouts here. */ | |
134 | len = 4; | |
135 | while (len > 0) | |
136 | { | |
137 | l = read(auth->fd, msg + 4 - len, len); | |
138 | if (l <= 0) | |
139 | { | |
140 | error("read auth->fd: %.100s", strerror(errno)); | |
141 | return 0; | |
142 | } | |
143 | len -= l; | |
144 | } | |
145 | ||
146 | /* Extract the length, and check it for sanity. (We cannot trust | |
147 | authentication agents). */ | |
148 | len = GET_32BIT(msg); | |
149 | if (len < 1 || len > 256*1024) | |
150 | fatal("Authentication reply message too long: %d\n", len); | |
151 | ||
152 | /* Read the packet itself. */ | |
153 | buffer_clear(&auth->identities); | |
154 | while (len > 0) | |
155 | { | |
156 | l = len; | |
157 | if (l > sizeof(msg)) | |
158 | l = sizeof(msg); | |
159 | l = read(auth->fd, msg, l); | |
160 | if (l <= 0) | |
161 | fatal("Incomplete authentication reply."); | |
162 | buffer_append(&auth->identities, (char *)msg, l); | |
163 | len -= l; | |
164 | } | |
165 | ||
166 | /* Get message type, and verify that we got a proper answer. */ | |
167 | buffer_get(&auth->identities, (char *)msg, 1); | |
168 | if (msg[0] != SSH_AGENT_RSA_IDENTITIES_ANSWER) | |
169 | fatal("Bad authentication reply message type: %d", msg[0]); | |
170 | ||
171 | /* Get the number of entries in the response and check it for sanity. */ | |
172 | auth->howmany = buffer_get_int(&auth->identities); | |
173 | if (auth->howmany > 1024) | |
174 | fatal("Too many identities in authentication reply: %d\n", auth->howmany); | |
175 | ||
176 | /* Return the first entry (if any). */ | |
177 | return ssh_get_next_identity(auth, bitsp, e, n, comment); | |
178 | } | |
179 | ||
180 | /* Returns the next authentication identity for the agent. Other functions | |
181 | can be called between this and ssh_get_first_identity or two calls of this | |
182 | function. This returns 0 if there are no more identities. The caller | |
183 | must free comment after a successful return. */ | |
184 | ||
185 | int | |
186 | ssh_get_next_identity(AuthenticationConnection *auth, | |
187 | int *bitsp, BIGNUM *e, BIGNUM *n, char **comment) | |
188 | { | |
189 | /* Return failure if no more entries. */ | |
190 | if (auth->howmany <= 0) | |
191 | return 0; | |
192 | ||
193 | /* Get the next entry from the packet. These will abort with a fatal | |
194 | error if the packet is too short or contains corrupt data. */ | |
195 | *bitsp = buffer_get_int(&auth->identities); | |
196 | buffer_get_bignum(&auth->identities, e); | |
197 | buffer_get_bignum(&auth->identities, n); | |
198 | *comment = buffer_get_string(&auth->identities, NULL); | |
199 | ||
200 | /* Decrement the number of remaining entries. */ | |
201 | auth->howmany--; | |
202 | ||
203 | return 1; | |
204 | } | |
205 | ||
206 | /* Generates a random challenge, sends it to the agent, and waits for response | |
207 | from the agent. Returns true (non-zero) if the agent gave the correct | |
208 | answer, zero otherwise. Response type selects the style of response | |
209 | desired, with 0 corresponding to protocol version 1.0 (no longer supported) | |
210 | and 1 corresponding to protocol version 1.1. */ | |
211 | ||
212 | int | |
213 | ssh_decrypt_challenge(AuthenticationConnection *auth, | |
214 | int bits, BIGNUM *e, BIGNUM *n, BIGNUM *challenge, | |
215 | unsigned char session_id[16], | |
216 | unsigned int response_type, | |
217 | unsigned char response[16]) | |
218 | { | |
219 | Buffer buffer; | |
220 | unsigned char buf[8192]; | |
221 | int len, l, i; | |
222 | ||
223 | /* Response type 0 is no longer supported. */ | |
224 | if (response_type == 0) | |
225 | fatal("Compatibility with ssh protocol version 1.0 no longer supported."); | |
226 | ||
227 | /* Format a message to the agent. */ | |
228 | buf[0] = SSH_AGENTC_RSA_CHALLENGE; | |
229 | buffer_init(&buffer); | |
230 | buffer_append(&buffer, (char *)buf, 1); | |
231 | buffer_put_int(&buffer, bits); | |
232 | buffer_put_bignum(&buffer, e); | |
233 | buffer_put_bignum(&buffer, n); | |
234 | buffer_put_bignum(&buffer, challenge); | |
235 | buffer_append(&buffer, (char *)session_id, 16); | |
236 | buffer_put_int(&buffer, response_type); | |
237 | ||
238 | /* Get the length of the message, and format it in the buffer. */ | |
239 | len = buffer_len(&buffer); | |
240 | PUT_32BIT(buf, len); | |
241 | ||
242 | /* Send the length and then the packet to the agent. */ | |
243 | if (write(auth->fd, buf, 4) != 4 || | |
244 | write(auth->fd, buffer_ptr(&buffer), buffer_len(&buffer)) != | |
245 | buffer_len(&buffer)) | |
246 | { | |
247 | error("Error writing to authentication socket."); | |
248 | error_cleanup: | |
249 | buffer_free(&buffer); | |
250 | return 0; | |
251 | } | |
252 | ||
253 | /* Wait for response from the agent. First read the length of the | |
254 | response packet. */ | |
255 | len = 4; | |
256 | while (len > 0) | |
257 | { | |
258 | l = read(auth->fd, buf + 4 - len, len); | |
259 | if (l <= 0) | |
260 | { | |
261 | error("Error reading response length from authentication socket."); | |
262 | goto error_cleanup; | |
263 | } | |
264 | len -= l; | |
265 | } | |
266 | ||
267 | /* Extract the length, and check it for sanity. */ | |
268 | len = GET_32BIT(buf); | |
269 | if (len > 256*1024) | |
270 | fatal("Authentication response too long: %d", len); | |
271 | ||
272 | /* Read the rest of the response in tothe buffer. */ | |
273 | buffer_clear(&buffer); | |
274 | while (len > 0) | |
275 | { | |
276 | l = len; | |
277 | if (l > sizeof(buf)) | |
278 | l = sizeof(buf); | |
279 | l = read(auth->fd, buf, l); | |
280 | if (l <= 0) | |
281 | { | |
282 | error("Error reading response from authentication socket."); | |
283 | goto error_cleanup; | |
284 | } | |
285 | buffer_append(&buffer, (char *)buf, l); | |
286 | len -= l; | |
287 | } | |
288 | ||
289 | /* Get the type of the packet. */ | |
290 | buffer_get(&buffer, (char *)buf, 1); | |
291 | ||
292 | /* Check for agent failure message. */ | |
293 | if (buf[0] == SSH_AGENT_FAILURE) | |
294 | { | |
295 | log("Agent admitted failure to authenticate using the key."); | |
296 | goto error_cleanup; | |
297 | } | |
298 | ||
299 | /* Now it must be an authentication response packet. */ | |
300 | if (buf[0] != SSH_AGENT_RSA_RESPONSE) | |
301 | fatal("Bad authentication response: %d", buf[0]); | |
302 | ||
303 | /* Get the response from the packet. This will abort with a fatal error | |
304 | if the packet is corrupt. */ | |
305 | for (i = 0; i < 16; i++) | |
306 | response[i] = buffer_get_char(&buffer); | |
307 | ||
308 | /* The buffer containing the packet is no longer needed. */ | |
309 | buffer_free(&buffer); | |
310 | ||
311 | /* Correct answer. */ | |
312 | return 1; | |
313 | } | |
314 | ||
315 | /* Adds an identity to the authentication server. This call is not meant to | |
316 | be used by normal applications. */ | |
317 | ||
318 | int ssh_add_identity(AuthenticationConnection *auth, | |
319 | RSA *key, const char *comment) | |
320 | { | |
321 | Buffer buffer; | |
322 | unsigned char buf[8192]; | |
323 | int len, l, type; | |
324 | ||
325 | /* Format a message to the agent. */ | |
326 | buffer_init(&buffer); | |
327 | buffer_put_char(&buffer, SSH_AGENTC_ADD_RSA_IDENTITY); | |
328 | buffer_put_int(&buffer, BN_num_bits(key->n)); | |
329 | buffer_put_bignum(&buffer, key->n); | |
330 | buffer_put_bignum(&buffer, key->e); | |
331 | buffer_put_bignum(&buffer, key->d); | |
332 | /* To keep within the protocol: p < q for ssh. in SSL p > q */ | |
333 | buffer_put_bignum(&buffer, key->iqmp); /* ssh key->u */ | |
334 | buffer_put_bignum(&buffer, key->q); /* ssh key->p, SSL key->q */ | |
335 | buffer_put_bignum(&buffer, key->p); /* ssh key->q, SSL key->p */ | |
336 | buffer_put_string(&buffer, comment, strlen(comment)); | |
337 | ||
338 | /* Get the length of the message, and format it in the buffer. */ | |
339 | len = buffer_len(&buffer); | |
340 | PUT_32BIT(buf, len); | |
341 | ||
342 | /* Send the length and then the packet to the agent. */ | |
343 | if (write(auth->fd, buf, 4) != 4 || | |
344 | write(auth->fd, buffer_ptr(&buffer), buffer_len(&buffer)) != | |
345 | buffer_len(&buffer)) | |
346 | { | |
347 | error("Error writing to authentication socket."); | |
348 | error_cleanup: | |
349 | buffer_free(&buffer); | |
350 | return 0; | |
351 | } | |
352 | ||
353 | /* Wait for response from the agent. First read the length of the | |
354 | response packet. */ | |
355 | len = 4; | |
356 | while (len > 0) | |
357 | { | |
358 | l = read(auth->fd, buf + 4 - len, len); | |
359 | if (l <= 0) | |
360 | { | |
361 | error("Error reading response length from authentication socket."); | |
362 | goto error_cleanup; | |
363 | } | |
364 | len -= l; | |
365 | } | |
366 | ||
367 | /* Extract the length, and check it for sanity. */ | |
368 | len = GET_32BIT(buf); | |
369 | if (len > 256*1024) | |
370 | fatal("Add identity response too long: %d", len); | |
371 | ||
372 | /* Read the rest of the response in tothe buffer. */ | |
373 | buffer_clear(&buffer); | |
374 | while (len > 0) | |
375 | { | |
376 | l = len; | |
377 | if (l > sizeof(buf)) | |
378 | l = sizeof(buf); | |
379 | l = read(auth->fd, buf, l); | |
380 | if (l <= 0) | |
381 | { | |
382 | error("Error reading response from authentication socket."); | |
383 | goto error_cleanup; | |
384 | } | |
385 | buffer_append(&buffer, (char *)buf, l); | |
386 | len -= l; | |
387 | } | |
388 | ||
389 | /* Get the type of the packet. */ | |
390 | type = buffer_get_char(&buffer); | |
391 | switch (type) | |
392 | { | |
393 | case SSH_AGENT_FAILURE: | |
394 | buffer_free(&buffer); | |
395 | return 0; | |
396 | case SSH_AGENT_SUCCESS: | |
397 | buffer_free(&buffer); | |
398 | return 1; | |
399 | default: | |
400 | fatal("Bad response to add identity from authentication agent: %d", | |
401 | type); | |
402 | } | |
403 | /*NOTREACHED*/ | |
404 | return 0; | |
405 | } | |
406 | ||
407 | /* Removes an identity from the authentication server. This call is not meant | |
408 | to be used by normal applications. */ | |
409 | ||
410 | int ssh_remove_identity(AuthenticationConnection *auth, RSA *key) | |
411 | { | |
412 | Buffer buffer; | |
413 | unsigned char buf[8192]; | |
414 | int len, l, type; | |
415 | ||
416 | /* Format a message to the agent. */ | |
417 | buffer_init(&buffer); | |
418 | buffer_put_char(&buffer, SSH_AGENTC_REMOVE_RSA_IDENTITY); | |
419 | buffer_put_int(&buffer, BN_num_bits(key->n)); | |
420 | buffer_put_bignum(&buffer, key->e); | |
421 | buffer_put_bignum(&buffer, key->n); | |
422 | ||
423 | /* Get the length of the message, and format it in the buffer. */ | |
424 | len = buffer_len(&buffer); | |
425 | PUT_32BIT(buf, len); | |
426 | ||
427 | /* Send the length and then the packet to the agent. */ | |
428 | if (write(auth->fd, buf, 4) != 4 || | |
429 | write(auth->fd, buffer_ptr(&buffer), buffer_len(&buffer)) != | |
430 | buffer_len(&buffer)) | |
431 | { | |
432 | error("Error writing to authentication socket."); | |
433 | error_cleanup: | |
434 | buffer_free(&buffer); | |
435 | return 0; | |
436 | } | |
437 | ||
438 | /* Wait for response from the agent. First read the length of the | |
439 | response packet. */ | |
440 | len = 4; | |
441 | while (len > 0) | |
442 | { | |
443 | l = read(auth->fd, buf + 4 - len, len); | |
444 | if (l <= 0) | |
445 | { | |
446 | error("Error reading response length from authentication socket."); | |
447 | goto error_cleanup; | |
448 | } | |
449 | len -= l; | |
450 | } | |
451 | ||
452 | /* Extract the length, and check it for sanity. */ | |
453 | len = GET_32BIT(buf); | |
454 | if (len > 256*1024) | |
455 | fatal("Remove identity response too long: %d", len); | |
456 | ||
457 | /* Read the rest of the response in tothe buffer. */ | |
458 | buffer_clear(&buffer); | |
459 | while (len > 0) | |
460 | { | |
461 | l = len; | |
462 | if (l > sizeof(buf)) | |
463 | l = sizeof(buf); | |
464 | l = read(auth->fd, buf, l); | |
465 | if (l <= 0) | |
466 | { | |
467 | error("Error reading response from authentication socket."); | |
468 | goto error_cleanup; | |
469 | } | |
470 | buffer_append(&buffer, (char *)buf, l); | |
471 | len -= l; | |
472 | } | |
473 | ||
474 | /* Get the type of the packet. */ | |
475 | type = buffer_get_char(&buffer); | |
476 | switch (type) | |
477 | { | |
478 | case SSH_AGENT_FAILURE: | |
479 | buffer_free(&buffer); | |
480 | return 0; | |
481 | case SSH_AGENT_SUCCESS: | |
482 | buffer_free(&buffer); | |
483 | return 1; | |
484 | default: | |
485 | fatal("Bad response to remove identity from authentication agent: %d", | |
486 | type); | |
487 | } | |
488 | /*NOTREACHED*/ | |
489 | return 0; | |
490 | } | |
491 | ||
492 | /* Removes all identities from the agent. This call is not meant | |
493 | to be used by normal applications. */ | |
494 | ||
495 | int ssh_remove_all_identities(AuthenticationConnection *auth) | |
496 | { | |
497 | Buffer buffer; | |
498 | unsigned char buf[8192]; | |
499 | int len, l, type; | |
500 | ||
501 | /* Get the length of the message, and format it in the buffer. */ | |
502 | PUT_32BIT(buf, 1); | |
503 | buf[4] = SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES; | |
504 | ||
505 | /* Send the length and then the packet to the agent. */ | |
506 | if (write(auth->fd, buf, 5) != 5) | |
507 | { | |
508 | error("Error writing to authentication socket."); | |
509 | return 0; | |
510 | } | |
511 | ||
512 | /* Wait for response from the agent. First read the length of the | |
513 | response packet. */ | |
514 | len = 4; | |
515 | while (len > 0) | |
516 | { | |
517 | l = read(auth->fd, buf + 4 - len, len); | |
518 | if (l <= 0) | |
519 | { | |
520 | error("Error reading response length from authentication socket."); | |
521 | return 0; | |
522 | } | |
523 | len -= l; | |
524 | } | |
525 | ||
526 | /* Extract the length, and check it for sanity. */ | |
527 | len = GET_32BIT(buf); | |
528 | if (len > 256*1024) | |
529 | fatal("Remove identity response too long: %d", len); | |
530 | ||
531 | /* Read the rest of the response into the buffer. */ | |
532 | buffer_init(&buffer); | |
533 | while (len > 0) | |
534 | { | |
535 | l = len; | |
536 | if (l > sizeof(buf)) | |
537 | l = sizeof(buf); | |
538 | l = read(auth->fd, buf, l); | |
539 | if (l <= 0) | |
540 | { | |
541 | error("Error reading response from authentication socket."); | |
542 | buffer_free(&buffer); | |
543 | return 0; | |
544 | } | |
545 | buffer_append(&buffer, (char *)buf, l); | |
546 | len -= l; | |
547 | } | |
548 | ||
549 | /* Get the type of the packet. */ | |
550 | type = buffer_get_char(&buffer); | |
551 | switch (type) | |
552 | { | |
553 | case SSH_AGENT_FAILURE: | |
554 | buffer_free(&buffer); | |
555 | return 0; | |
556 | case SSH_AGENT_SUCCESS: | |
557 | buffer_free(&buffer); | |
558 | return 1; | |
559 | default: | |
560 | fatal("Bad response to remove identity from authentication agent: %d", | |
561 | type); | |
562 | } | |
563 | /*NOTREACHED*/ | |
564 | return 0; | |
565 | } |