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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" | |
089fbbd2 | 17 | RCSID("$OpenBSD: authfd.c,v 1.21 2000/06/26 09:22:29 markus Exp $"); |
8efc0c15 | 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 | ||
089fbbd2 | 29 | /* helper */ |
30 | int ssh_agent_get_reply(AuthenticationConnection *auth); | |
31 | ||
8efc0c15 | 32 | /* Returns the number of the authentication fd, or -1 if there is none. */ |
33 | ||
34 | int | |
35 | ssh_get_authentication_socket() | |
36 | { | |
5260325f | 37 | const char *authsocket; |
38 | int sock; | |
39 | struct sockaddr_un sunaddr; | |
40 | ||
41 | authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME); | |
42 | if (!authsocket) | |
43 | return -1; | |
44 | ||
45 | sunaddr.sun_family = AF_UNIX; | |
46 | strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path)); | |
47 | ||
48 | sock = socket(AF_UNIX, SOCK_STREAM, 0); | |
49 | if (sock < 0) | |
50 | return -1; | |
51 | ||
52 | /* close on exec */ | |
53 | if (fcntl(sock, F_SETFD, 1) == -1) { | |
54 | close(sock); | |
55 | return -1; | |
56 | } | |
57 | if (connect(sock, (struct sockaddr *) & sunaddr, sizeof(sunaddr)) < 0) { | |
58 | close(sock); | |
59 | return -1; | |
60 | } | |
61 | return sock; | |
8efc0c15 | 62 | } |
63 | ||
aa3378df | 64 | /* |
65 | * Closes the agent socket if it should be closed (depends on how it was | |
66 | * obtained). The argument must have been returned by | |
67 | * ssh_get_authentication_socket(). | |
68 | */ | |
8efc0c15 | 69 | |
6ae2364d | 70 | void |
5260325f | 71 | ssh_close_authentication_socket(int sock) |
8efc0c15 | 72 | { |
5260325f | 73 | if (getenv(SSH_AUTHSOCKET_ENV_NAME)) |
74 | close(sock); | |
8efc0c15 | 75 | } |
76 | ||
aa3378df | 77 | /* |
78 | * Opens and connects a private socket for communication with the | |
79 | * authentication agent. Returns the file descriptor (which must be | |
80 | * shut down and closed by the caller when no longer needed). | |
81 | * Returns NULL if an error occurred and the connection could not be | |
82 | * opened. | |
83 | */ | |
8efc0c15 | 84 | |
5260325f | 85 | AuthenticationConnection * |
86 | ssh_get_authentication_connection() | |
8efc0c15 | 87 | { |
5260325f | 88 | AuthenticationConnection *auth; |
89 | int sock; | |
90 | ||
91 | sock = ssh_get_authentication_socket(); | |
92 | ||
aa3378df | 93 | /* |
94 | * Fail if we couldn't obtain a connection. This happens if we | |
95 | * exited due to a timeout. | |
96 | */ | |
5260325f | 97 | if (sock < 0) |
98 | return NULL; | |
99 | ||
5260325f | 100 | auth = xmalloc(sizeof(*auth)); |
101 | auth->fd = sock; | |
102 | buffer_init(&auth->packet); | |
103 | buffer_init(&auth->identities); | |
104 | auth->howmany = 0; | |
105 | ||
106 | return auth; | |
8efc0c15 | 107 | } |
108 | ||
aa3378df | 109 | /* |
110 | * Closes the connection to the authentication agent and frees any associated | |
111 | * memory. | |
112 | */ | |
8efc0c15 | 113 | |
6ae2364d | 114 | void |
5260325f | 115 | ssh_close_authentication_connection(AuthenticationConnection *ac) |
8efc0c15 | 116 | { |
5260325f | 117 | buffer_free(&ac->packet); |
118 | buffer_free(&ac->identities); | |
119 | close(ac->fd); | |
120 | xfree(ac); | |
8efc0c15 | 121 | } |
122 | ||
aa3378df | 123 | /* |
124 | * Returns the first authentication identity held by the agent. | |
125 | * Returns true if an identity is available, 0 otherwise. | |
126 | * The caller must initialize the integers before the call, and free the | |
127 | * comment after a successful call (before calling ssh_get_next_identity). | |
128 | */ | |
8efc0c15 | 129 | |
130 | int | |
131 | ssh_get_first_identity(AuthenticationConnection *auth, | |
4d195447 | 132 | BIGNUM *e, BIGNUM *n, char **comment) |
8efc0c15 | 133 | { |
5260325f | 134 | unsigned char msg[8192]; |
135 | int len, l; | |
136 | ||
aa3378df | 137 | /* |
138 | * Send a message to the agent requesting for a list of the | |
139 | * identities it can represent. | |
140 | */ | |
5260325f | 141 | msg[0] = 0; |
142 | msg[1] = 0; | |
143 | msg[2] = 0; | |
144 | msg[3] = 1; | |
145 | msg[4] = SSH_AGENTC_REQUEST_RSA_IDENTITIES; | |
a408af76 | 146 | if (atomicio(write, auth->fd, msg, 5) != 5) { |
5260325f | 147 | error("write auth->fd: %.100s", strerror(errno)); |
148 | return 0; | |
149 | } | |
150 | /* Read the length of the response. XXX implement timeouts here. */ | |
151 | len = 4; | |
152 | while (len > 0) { | |
153 | l = read(auth->fd, msg + 4 - len, len); | |
154 | if (l <= 0) { | |
155 | error("read auth->fd: %.100s", strerror(errno)); | |
156 | return 0; | |
157 | } | |
158 | len -= l; | |
159 | } | |
160 | ||
aa3378df | 161 | /* |
162 | * Extract the length, and check it for sanity. (We cannot trust | |
163 | * authentication agents). | |
164 | */ | |
5260325f | 165 | len = GET_32BIT(msg); |
166 | if (len < 1 || len > 256 * 1024) | |
167 | fatal("Authentication reply message too long: %d\n", len); | |
168 | ||
169 | /* Read the packet itself. */ | |
170 | buffer_clear(&auth->identities); | |
171 | while (len > 0) { | |
172 | l = len; | |
173 | if (l > sizeof(msg)) | |
174 | l = sizeof(msg); | |
175 | l = read(auth->fd, msg, l); | |
176 | if (l <= 0) | |
177 | fatal("Incomplete authentication reply."); | |
178 | buffer_append(&auth->identities, (char *) msg, l); | |
179 | len -= l; | |
8efc0c15 | 180 | } |
5260325f | 181 | |
182 | /* Get message type, and verify that we got a proper answer. */ | |
183 | buffer_get(&auth->identities, (char *) msg, 1); | |
184 | if (msg[0] != SSH_AGENT_RSA_IDENTITIES_ANSWER) | |
185 | fatal("Bad authentication reply message type: %d", msg[0]); | |
186 | ||
187 | /* Get the number of entries in the response and check it for sanity. */ | |
188 | auth->howmany = buffer_get_int(&auth->identities); | |
189 | if (auth->howmany > 1024) | |
190 | fatal("Too many identities in authentication reply: %d\n", auth->howmany); | |
191 | ||
192 | /* Return the first entry (if any). */ | |
193 | return ssh_get_next_identity(auth, e, n, comment); | |
8efc0c15 | 194 | } |
195 | ||
aa3378df | 196 | /* |
197 | * Returns the next authentication identity for the agent. Other functions | |
198 | * can be called between this and ssh_get_first_identity or two calls of this | |
199 | * function. This returns 0 if there are no more identities. The caller | |
200 | * must free comment after a successful return. | |
201 | */ | |
8efc0c15 | 202 | |
203 | int | |
204 | ssh_get_next_identity(AuthenticationConnection *auth, | |
4d195447 | 205 | BIGNUM *e, BIGNUM *n, char **comment) |
8efc0c15 | 206 | { |
5260325f | 207 | unsigned int bits; |
4d195447 | 208 | |
5260325f | 209 | /* Return failure if no more entries. */ |
210 | if (auth->howmany <= 0) | |
211 | return 0; | |
8efc0c15 | 212 | |
aa3378df | 213 | /* |
214 | * Get the next entry from the packet. These will abort with a fatal | |
215 | * error if the packet is too short or contains corrupt data. | |
216 | */ | |
5260325f | 217 | bits = buffer_get_int(&auth->identities); |
218 | buffer_get_bignum(&auth->identities, e); | |
219 | buffer_get_bignum(&auth->identities, n); | |
220 | *comment = buffer_get_string(&auth->identities, NULL); | |
8efc0c15 | 221 | |
5260325f | 222 | if (bits != BN_num_bits(n)) |
0b242b12 | 223 | log("Warning: identity keysize mismatch: actual %d, announced %u", |
224 | BN_num_bits(n), bits); | |
4d195447 | 225 | |
5260325f | 226 | /* Decrement the number of remaining entries. */ |
227 | auth->howmany--; | |
8efc0c15 | 228 | |
5260325f | 229 | return 1; |
8efc0c15 | 230 | } |
231 | ||
aa3378df | 232 | /* |
233 | * Generates a random challenge, sends it to the agent, and waits for | |
234 | * response from the agent. Returns true (non-zero) if the agent gave the | |
235 | * correct answer, zero otherwise. Response type selects the style of | |
236 | * response desired, with 0 corresponding to protocol version 1.0 (no longer | |
237 | * supported) and 1 corresponding to protocol version 1.1. | |
238 | */ | |
8efc0c15 | 239 | |
240 | int | |
241 | ssh_decrypt_challenge(AuthenticationConnection *auth, | |
5260325f | 242 | BIGNUM* e, BIGNUM *n, BIGNUM *challenge, |
8efc0c15 | 243 | unsigned char session_id[16], |
244 | unsigned int response_type, | |
245 | unsigned char response[16]) | |
246 | { | |
5260325f | 247 | Buffer buffer; |
248 | unsigned char buf[8192]; | |
249 | int len, l, i; | |
250 | ||
251 | /* Response type 0 is no longer supported. */ | |
252 | if (response_type == 0) | |
253 | fatal("Compatibility with ssh protocol version 1.0 no longer supported."); | |
254 | ||
255 | /* Format a message to the agent. */ | |
256 | buf[0] = SSH_AGENTC_RSA_CHALLENGE; | |
257 | buffer_init(&buffer); | |
258 | buffer_append(&buffer, (char *) buf, 1); | |
259 | buffer_put_int(&buffer, BN_num_bits(n)); | |
260 | buffer_put_bignum(&buffer, e); | |
261 | buffer_put_bignum(&buffer, n); | |
262 | buffer_put_bignum(&buffer, challenge); | |
263 | buffer_append(&buffer, (char *) session_id, 16); | |
264 | buffer_put_int(&buffer, response_type); | |
265 | ||
266 | /* Get the length of the message, and format it in the buffer. */ | |
267 | len = buffer_len(&buffer); | |
268 | PUT_32BIT(buf, len); | |
269 | ||
270 | /* Send the length and then the packet to the agent. */ | |
a408af76 | 271 | if (atomicio(write, auth->fd, buf, 4) != 4 || |
272 | atomicio(write, auth->fd, buffer_ptr(&buffer), | |
273 | buffer_len(&buffer)) != buffer_len(&buffer)) { | |
5260325f | 274 | error("Error writing to authentication socket."); |
275 | error_cleanup: | |
276 | buffer_free(&buffer); | |
277 | return 0; | |
278 | } | |
aa3378df | 279 | /* |
280 | * Wait for response from the agent. First read the length of the | |
281 | * response packet. | |
282 | */ | |
5260325f | 283 | len = 4; |
284 | while (len > 0) { | |
285 | l = read(auth->fd, buf + 4 - len, len); | |
286 | if (l <= 0) { | |
287 | error("Error reading response length from authentication socket."); | |
288 | goto error_cleanup; | |
289 | } | |
290 | len -= l; | |
291 | } | |
292 | ||
293 | /* Extract the length, and check it for sanity. */ | |
294 | len = GET_32BIT(buf); | |
295 | if (len > 256 * 1024) | |
296 | fatal("Authentication response too long: %d", len); | |
297 | ||
298 | /* Read the rest of the response in tothe buffer. */ | |
299 | buffer_clear(&buffer); | |
300 | while (len > 0) { | |
301 | l = len; | |
302 | if (l > sizeof(buf)) | |
303 | l = sizeof(buf); | |
304 | l = read(auth->fd, buf, l); | |
305 | if (l <= 0) { | |
306 | error("Error reading response from authentication socket."); | |
307 | goto error_cleanup; | |
308 | } | |
309 | buffer_append(&buffer, (char *) buf, l); | |
310 | len -= l; | |
8efc0c15 | 311 | } |
5260325f | 312 | |
313 | /* Get the type of the packet. */ | |
314 | buffer_get(&buffer, (char *) buf, 1); | |
315 | ||
316 | /* Check for agent failure message. */ | |
317 | if (buf[0] == SSH_AGENT_FAILURE) { | |
318 | log("Agent admitted failure to authenticate using the key."); | |
319 | goto error_cleanup; | |
8efc0c15 | 320 | } |
5260325f | 321 | /* Now it must be an authentication response packet. */ |
322 | if (buf[0] != SSH_AGENT_RSA_RESPONSE) | |
323 | fatal("Bad authentication response: %d", buf[0]); | |
324 | ||
aa3378df | 325 | /* |
326 | * Get the response from the packet. This will abort with a fatal | |
327 | * error if the packet is corrupt. | |
328 | */ | |
5260325f | 329 | for (i = 0; i < 16; i++) |
330 | response[i] = buffer_get_char(&buffer); | |
331 | ||
332 | /* The buffer containing the packet is no longer needed. */ | |
333 | buffer_free(&buffer); | |
334 | ||
335 | /* Correct answer. */ | |
336 | return 1; | |
337 | } | |
8efc0c15 | 338 | |
aa3378df | 339 | /* |
340 | * Adds an identity to the authentication server. This call is not meant to | |
341 | * be used by normal applications. | |
342 | */ | |
8efc0c15 | 343 | |
6ae2364d | 344 | int |
5260325f | 345 | ssh_add_identity(AuthenticationConnection *auth, |
346 | RSA * key, const char *comment) | |
8efc0c15 | 347 | { |
5260325f | 348 | Buffer buffer; |
349 | unsigned char buf[8192]; | |
089fbbd2 | 350 | int len; |
5260325f | 351 | |
352 | /* Format a message to the agent. */ | |
353 | buffer_init(&buffer); | |
354 | buffer_put_char(&buffer, SSH_AGENTC_ADD_RSA_IDENTITY); | |
355 | buffer_put_int(&buffer, BN_num_bits(key->n)); | |
356 | buffer_put_bignum(&buffer, key->n); | |
357 | buffer_put_bignum(&buffer, key->e); | |
358 | buffer_put_bignum(&buffer, key->d); | |
359 | /* To keep within the protocol: p < q for ssh. in SSL p > q */ | |
360 | buffer_put_bignum(&buffer, key->iqmp); /* ssh key->u */ | |
361 | buffer_put_bignum(&buffer, key->q); /* ssh key->p, SSL key->q */ | |
362 | buffer_put_bignum(&buffer, key->p); /* ssh key->q, SSL key->p */ | |
363 | buffer_put_string(&buffer, comment, strlen(comment)); | |
364 | ||
365 | /* Get the length of the message, and format it in the buffer. */ | |
366 | len = buffer_len(&buffer); | |
367 | PUT_32BIT(buf, len); | |
368 | ||
369 | /* Send the length and then the packet to the agent. */ | |
a408af76 | 370 | if (atomicio(write, auth->fd, buf, 4) != 4 || |
371 | atomicio(write, auth->fd, buffer_ptr(&buffer), | |
372 | buffer_len(&buffer)) != buffer_len(&buffer)) { | |
5260325f | 373 | error("Error writing to authentication socket."); |
5260325f | 374 | buffer_free(&buffer); |
375 | return 0; | |
376 | } | |
089fbbd2 | 377 | buffer_free(&buffer); |
378 | return ssh_agent_get_reply(auth); | |
5260325f | 379 | } |
380 | ||
aa3378df | 381 | /* |
382 | * Removes an identity from the authentication server. This call is not | |
383 | * meant to be used by normal applications. | |
384 | */ | |
8efc0c15 | 385 | |
6ae2364d | 386 | int |
5260325f | 387 | ssh_remove_identity(AuthenticationConnection *auth, RSA *key) |
8efc0c15 | 388 | { |
5260325f | 389 | Buffer buffer; |
089fbbd2 | 390 | unsigned char buf[5]; |
391 | int len; | |
5260325f | 392 | |
393 | /* Format a message to the agent. */ | |
394 | buffer_init(&buffer); | |
395 | buffer_put_char(&buffer, SSH_AGENTC_REMOVE_RSA_IDENTITY); | |
396 | buffer_put_int(&buffer, BN_num_bits(key->n)); | |
397 | buffer_put_bignum(&buffer, key->e); | |
398 | buffer_put_bignum(&buffer, key->n); | |
399 | ||
400 | /* Get the length of the message, and format it in the buffer. */ | |
401 | len = buffer_len(&buffer); | |
402 | PUT_32BIT(buf, len); | |
403 | ||
404 | /* Send the length and then the packet to the agent. */ | |
a408af76 | 405 | if (atomicio(write, auth->fd, buf, 4) != 4 || |
406 | atomicio(write, auth->fd, buffer_ptr(&buffer), | |
407 | buffer_len(&buffer)) != buffer_len(&buffer)) { | |
5260325f | 408 | error("Error writing to authentication socket."); |
5260325f | 409 | buffer_free(&buffer); |
410 | return 0; | |
411 | } | |
089fbbd2 | 412 | buffer_free(&buffer); |
413 | return ssh_agent_get_reply(auth); | |
5260325f | 414 | } |
415 | ||
aa3378df | 416 | /* |
417 | * Removes all identities from the agent. This call is not meant to be used | |
418 | * by normal applications. | |
419 | */ | |
8efc0c15 | 420 | |
6ae2364d | 421 | int |
5260325f | 422 | ssh_remove_all_identities(AuthenticationConnection *auth) |
8efc0c15 | 423 | { |
089fbbd2 | 424 | unsigned char buf[5]; |
5260325f | 425 | |
426 | /* Get the length of the message, and format it in the buffer. */ | |
427 | PUT_32BIT(buf, 1); | |
428 | buf[4] = SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES; | |
429 | ||
430 | /* Send the length and then the packet to the agent. */ | |
a408af76 | 431 | if (atomicio(write, auth->fd, buf, 5) != 5) { |
5260325f | 432 | error("Error writing to authentication socket."); |
433 | return 0; | |
434 | } | |
089fbbd2 | 435 | return ssh_agent_get_reply(auth); |
436 | } | |
437 | ||
438 | /* | |
439 | * Read for reply from agent. returns 1 for success, 0 on error | |
440 | */ | |
441 | ||
442 | int | |
443 | ssh_agent_get_reply(AuthenticationConnection *auth) | |
444 | { | |
445 | Buffer buffer; | |
446 | unsigned char buf[8192]; | |
447 | int len, l, type; | |
448 | ||
aa3378df | 449 | /* |
450 | * Wait for response from the agent. First read the length of the | |
451 | * response packet. | |
452 | */ | |
5260325f | 453 | len = 4; |
454 | while (len > 0) { | |
455 | l = read(auth->fd, buf + 4 - len, len); | |
456 | if (l <= 0) { | |
457 | error("Error reading response length from authentication socket."); | |
089fbbd2 | 458 | buffer_free(&buffer); |
5260325f | 459 | return 0; |
460 | } | |
461 | len -= l; | |
462 | } | |
463 | ||
464 | /* Extract the length, and check it for sanity. */ | |
465 | len = GET_32BIT(buf); | |
466 | if (len > 256 * 1024) | |
089fbbd2 | 467 | fatal("Response from agent too long: %d", len); |
5260325f | 468 | |
089fbbd2 | 469 | /* Read the rest of the response in to the buffer. */ |
5260325f | 470 | buffer_init(&buffer); |
471 | while (len > 0) { | |
472 | l = len; | |
473 | if (l > sizeof(buf)) | |
474 | l = sizeof(buf); | |
475 | l = read(auth->fd, buf, l); | |
476 | if (l <= 0) { | |
477 | error("Error reading response from authentication socket."); | |
478 | buffer_free(&buffer); | |
479 | return 0; | |
480 | } | |
481 | buffer_append(&buffer, (char *) buf, l); | |
482 | len -= l; | |
8efc0c15 | 483 | } |
5260325f | 484 | |
485 | /* Get the type of the packet. */ | |
486 | type = buffer_get_char(&buffer); | |
089fbbd2 | 487 | buffer_free(&buffer); |
5260325f | 488 | switch (type) { |
489 | case SSH_AGENT_FAILURE: | |
5260325f | 490 | return 0; |
491 | case SSH_AGENT_SUCCESS: | |
5260325f | 492 | return 1; |
493 | default: | |
089fbbd2 | 494 | fatal("Bad response from authentication agent: %d", type); |
8efc0c15 | 495 | } |
5260325f | 496 | /* NOTREACHED */ |
497 | return 0; | |
498 | } |