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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 | * |
2e73a022 | 14 | * SSH2 implementation, |
15 | * Copyright (c) 2000 Markus Friedl. All rights reserved. | |
16 | * | |
5260325f | 17 | */ |
8efc0c15 | 18 | |
19 | #include "includes.h" | |
2e73a022 | 20 | RCSID("$OpenBSD: authfd.c,v 1.25 2000/08/19 21:34:42 markus Exp $"); |
8efc0c15 | 21 | |
22 | #include "ssh.h" | |
23 | #include "rsa.h" | |
8efc0c15 | 24 | #include "buffer.h" |
25 | #include "bufaux.h" | |
26 | #include "xmalloc.h" | |
27 | #include "getput.h" | |
28 | ||
29 | #include <openssl/rsa.h> | |
4c8722d9 | 30 | #include <openssl/dsa.h> |
31 | #include <openssl/evp.h> | |
32 | #include "key.h" | |
33 | #include "authfd.h" | |
34 | #include "kex.h" | |
2e73a022 | 35 | #include "dsa.h" |
8efc0c15 | 36 | |
089fbbd2 | 37 | /* helper */ |
c345cf9d | 38 | int decode_reply(int type); |
089fbbd2 | 39 | |
8efc0c15 | 40 | /* Returns the number of the authentication fd, or -1 if there is none. */ |
41 | ||
42 | int | |
43 | ssh_get_authentication_socket() | |
44 | { | |
5260325f | 45 | const char *authsocket; |
c345cf9d | 46 | int sock, len; |
5260325f | 47 | struct sockaddr_un sunaddr; |
48 | ||
49 | authsocket = getenv(SSH_AUTHSOCKET_ENV_NAME); | |
50 | if (!authsocket) | |
51 | return -1; | |
52 | ||
53 | sunaddr.sun_family = AF_UNIX; | |
54 | strlcpy(sunaddr.sun_path, authsocket, sizeof(sunaddr.sun_path)); | |
c345cf9d | 55 | #ifdef HAVE_SUN_LEN_IN_SOCKADDR_UN |
56 | sunaddr.sun_len = len = SUN_LEN(&sunaddr)+1; | |
57 | #else /* HAVE_SUN_LEN_IN_SOCKADDR_UN */ | |
58 | len = SUN_LEN(&sunaddr)+1; | |
59 | #endif /* HAVE_SUN_LEN_IN_SOCKADDR_UN */ | |
5260325f | 60 | |
61 | sock = socket(AF_UNIX, SOCK_STREAM, 0); | |
62 | if (sock < 0) | |
63 | return -1; | |
64 | ||
65 | /* close on exec */ | |
66 | if (fcntl(sock, F_SETFD, 1) == -1) { | |
67 | close(sock); | |
68 | return -1; | |
69 | } | |
c345cf9d | 70 | if (connect(sock, (struct sockaddr *) & sunaddr, len) < 0) { |
5260325f | 71 | close(sock); |
72 | return -1; | |
73 | } | |
74 | return sock; | |
8efc0c15 | 75 | } |
76 | ||
c345cf9d | 77 | int |
2e73a022 | 78 | ssh_request_reply(AuthenticationConnection *auth, Buffer *request, Buffer *reply) |
c345cf9d | 79 | { |
80 | int l, len; | |
81 | char buf[1024]; | |
82 | ||
83 | /* Get the length of the message, and format it in the buffer. */ | |
84 | len = buffer_len(request); | |
85 | PUT_32BIT(buf, len); | |
86 | ||
87 | /* Send the length and then the packet to the agent. */ | |
88 | if (atomicio(write, auth->fd, buf, 4) != 4 || | |
89 | atomicio(write, auth->fd, buffer_ptr(request), | |
90 | buffer_len(request)) != buffer_len(request)) { | |
91 | error("Error writing to authentication socket."); | |
92 | return 0; | |
93 | } | |
94 | /* | |
95 | * Wait for response from the agent. First read the length of the | |
96 | * response packet. | |
97 | */ | |
98 | len = 4; | |
99 | while (len > 0) { | |
100 | l = read(auth->fd, buf + 4 - len, len); | |
101 | if (l <= 0) { | |
102 | error("Error reading response length from authentication socket."); | |
103 | return 0; | |
104 | } | |
105 | len -= l; | |
106 | } | |
107 | ||
108 | /* Extract the length, and check it for sanity. */ | |
109 | len = GET_32BIT(buf); | |
110 | if (len > 256 * 1024) | |
111 | fatal("Authentication response too long: %d", len); | |
112 | ||
113 | /* Read the rest of the response in to the buffer. */ | |
114 | buffer_clear(reply); | |
115 | while (len > 0) { | |
116 | l = len; | |
117 | if (l > sizeof(buf)) | |
118 | l = sizeof(buf); | |
119 | l = read(auth->fd, buf, l); | |
120 | if (l <= 0) { | |
121 | error("Error reading response from authentication socket."); | |
122 | return 0; | |
123 | } | |
124 | buffer_append(reply, (char *) buf, l); | |
125 | len -= l; | |
126 | } | |
127 | return 1; | |
128 | } | |
129 | ||
aa3378df | 130 | /* |
131 | * Closes the agent socket if it should be closed (depends on how it was | |
132 | * obtained). The argument must have been returned by | |
133 | * ssh_get_authentication_socket(). | |
134 | */ | |
8efc0c15 | 135 | |
6ae2364d | 136 | void |
5260325f | 137 | ssh_close_authentication_socket(int sock) |
8efc0c15 | 138 | { |
5260325f | 139 | if (getenv(SSH_AUTHSOCKET_ENV_NAME)) |
140 | close(sock); | |
8efc0c15 | 141 | } |
142 | ||
aa3378df | 143 | /* |
144 | * Opens and connects a private socket for communication with the | |
145 | * authentication agent. Returns the file descriptor (which must be | |
146 | * shut down and closed by the caller when no longer needed). | |
147 | * Returns NULL if an error occurred and the connection could not be | |
148 | * opened. | |
149 | */ | |
8efc0c15 | 150 | |
5260325f | 151 | AuthenticationConnection * |
152 | ssh_get_authentication_connection() | |
8efc0c15 | 153 | { |
5260325f | 154 | AuthenticationConnection *auth; |
155 | int sock; | |
156 | ||
157 | sock = ssh_get_authentication_socket(); | |
158 | ||
aa3378df | 159 | /* |
160 | * Fail if we couldn't obtain a connection. This happens if we | |
161 | * exited due to a timeout. | |
162 | */ | |
5260325f | 163 | if (sock < 0) |
164 | return NULL; | |
165 | ||
5260325f | 166 | auth = xmalloc(sizeof(*auth)); |
167 | auth->fd = sock; | |
5260325f | 168 | buffer_init(&auth->identities); |
169 | auth->howmany = 0; | |
170 | ||
171 | return auth; | |
8efc0c15 | 172 | } |
173 | ||
aa3378df | 174 | /* |
175 | * Closes the connection to the authentication agent and frees any associated | |
176 | * memory. | |
177 | */ | |
8efc0c15 | 178 | |
6ae2364d | 179 | void |
2e73a022 | 180 | ssh_close_authentication_connection(AuthenticationConnection *auth) |
8efc0c15 | 181 | { |
2e73a022 | 182 | buffer_free(&auth->identities); |
183 | close(auth->fd); | |
184 | xfree(auth); | |
8efc0c15 | 185 | } |
186 | ||
aa3378df | 187 | /* |
188 | * Returns the first authentication identity held by the agent. | |
aa3378df | 189 | */ |
8efc0c15 | 190 | |
2e73a022 | 191 | Key * |
192 | ssh_get_first_identity(AuthenticationConnection *auth, char **comment, int version) | |
8efc0c15 | 193 | { |
2e73a022 | 194 | int type, code1 = 0, code2 = 0; |
c345cf9d | 195 | Buffer request; |
2e73a022 | 196 | |
197 | switch(version){ | |
198 | case 1: | |
199 | code1 = SSH_AGENTC_REQUEST_RSA_IDENTITIES; | |
200 | code2 = SSH_AGENT_RSA_IDENTITIES_ANSWER; | |
201 | break; | |
202 | case 2: | |
203 | code1 = SSH2_AGENTC_REQUEST_IDENTITIES; | |
204 | code2 = SSH2_AGENT_IDENTITIES_ANSWER; | |
205 | break; | |
206 | default: | |
207 | return NULL; | |
208 | } | |
5260325f | 209 | |
aa3378df | 210 | /* |
211 | * Send a message to the agent requesting for a list of the | |
212 | * identities it can represent. | |
213 | */ | |
c345cf9d | 214 | buffer_init(&request); |
2e73a022 | 215 | buffer_put_char(&request, code1); |
5260325f | 216 | |
5260325f | 217 | buffer_clear(&auth->identities); |
c345cf9d | 218 | if (ssh_request_reply(auth, &request, &auth->identities) == 0) { |
219 | buffer_free(&request); | |
2e73a022 | 220 | return NULL; |
8efc0c15 | 221 | } |
c345cf9d | 222 | buffer_free(&request); |
5260325f | 223 | |
224 | /* Get message type, and verify that we got a proper answer. */ | |
c345cf9d | 225 | type = buffer_get_char(&auth->identities); |
2e73a022 | 226 | if (type == SSH_AGENT_FAILURE) { |
227 | return NULL; | |
228 | } else if (type != code2) { | |
c345cf9d | 229 | fatal("Bad authentication reply message type: %d", type); |
2e73a022 | 230 | } |
5260325f | 231 | |
232 | /* Get the number of entries in the response and check it for sanity. */ | |
233 | auth->howmany = buffer_get_int(&auth->identities); | |
234 | if (auth->howmany > 1024) | |
c345cf9d | 235 | fatal("Too many identities in authentication reply: %d\n", |
236 | auth->howmany); | |
5260325f | 237 | |
238 | /* Return the first entry (if any). */ | |
2e73a022 | 239 | return ssh_get_next_identity(auth, comment, version); |
8efc0c15 | 240 | } |
241 | ||
2e73a022 | 242 | Key * |
243 | ssh_get_next_identity(AuthenticationConnection *auth, char **comment, int version) | |
8efc0c15 | 244 | { |
5260325f | 245 | unsigned int bits; |
2e73a022 | 246 | unsigned char *blob; |
247 | unsigned int blen; | |
248 | Key *key = NULL; | |
4d195447 | 249 | |
5260325f | 250 | /* Return failure if no more entries. */ |
251 | if (auth->howmany <= 0) | |
2e73a022 | 252 | return NULL; |
8efc0c15 | 253 | |
aa3378df | 254 | /* |
255 | * Get the next entry from the packet. These will abort with a fatal | |
256 | * error if the packet is too short or contains corrupt data. | |
257 | */ | |
2e73a022 | 258 | switch(version){ |
259 | case 1: | |
260 | key = key_new(KEY_RSA); | |
261 | bits = buffer_get_int(&auth->identities); | |
262 | buffer_get_bignum(&auth->identities, key->rsa->e); | |
263 | buffer_get_bignum(&auth->identities, key->rsa->n); | |
264 | *comment = buffer_get_string(&auth->identities, NULL); | |
265 | if (bits != BN_num_bits(key->rsa->n)) | |
266 | log("Warning: identity keysize mismatch: actual %d, announced %u", | |
267 | BN_num_bits(key->rsa->n), bits); | |
268 | break; | |
269 | case 2: | |
270 | blob = buffer_get_string(&auth->identities, &blen); | |
271 | *comment = buffer_get_string(&auth->identities, NULL); | |
272 | key = dsa_key_from_blob(blob, blen); | |
273 | xfree(blob); | |
274 | break; | |
275 | default: | |
276 | return NULL; | |
277 | break; | |
278 | } | |
5260325f | 279 | /* Decrement the number of remaining entries. */ |
280 | auth->howmany--; | |
2e73a022 | 281 | return key; |
8efc0c15 | 282 | } |
283 | ||
aa3378df | 284 | /* |
285 | * Generates a random challenge, sends it to the agent, and waits for | |
286 | * response from the agent. Returns true (non-zero) if the agent gave the | |
287 | * correct answer, zero otherwise. Response type selects the style of | |
288 | * response desired, with 0 corresponding to protocol version 1.0 (no longer | |
289 | * supported) and 1 corresponding to protocol version 1.1. | |
290 | */ | |
8efc0c15 | 291 | |
292 | int | |
293 | ssh_decrypt_challenge(AuthenticationConnection *auth, | |
2e73a022 | 294 | Key* key, BIGNUM *challenge, |
c345cf9d | 295 | unsigned char session_id[16], |
296 | unsigned int response_type, | |
297 | unsigned char response[16]) | |
8efc0c15 | 298 | { |
5260325f | 299 | Buffer buffer; |
c345cf9d | 300 | int success = 0; |
301 | int i; | |
302 | int type; | |
5260325f | 303 | |
2e73a022 | 304 | if (key->type != KEY_RSA) |
305 | return 0; | |
306 | if (response_type == 0) { | |
307 | log("Compatibility with ssh protocol version 1.0 no longer supported."); | |
308 | return 0; | |
309 | } | |
5260325f | 310 | buffer_init(&buffer); |
c345cf9d | 311 | buffer_put_char(&buffer, SSH_AGENTC_RSA_CHALLENGE); |
2e73a022 | 312 | buffer_put_int(&buffer, BN_num_bits(key->rsa->n)); |
313 | buffer_put_bignum(&buffer, key->rsa->e); | |
314 | buffer_put_bignum(&buffer, key->rsa->n); | |
5260325f | 315 | buffer_put_bignum(&buffer, challenge); |
316 | buffer_append(&buffer, (char *) session_id, 16); | |
317 | buffer_put_int(&buffer, response_type); | |
318 | ||
c345cf9d | 319 | if (ssh_request_reply(auth, &buffer, &buffer) == 0) { |
5260325f | 320 | buffer_free(&buffer); |
321 | return 0; | |
322 | } | |
c345cf9d | 323 | type = buffer_get_char(&buffer); |
5260325f | 324 | |
c345cf9d | 325 | if (type == SSH_AGENT_FAILURE) { |
5260325f | 326 | log("Agent admitted failure to authenticate using the key."); |
c345cf9d | 327 | } else if (type != SSH_AGENT_RSA_RESPONSE) { |
328 | fatal("Bad authentication response: %d", type); | |
329 | } else { | |
330 | success = 1; | |
331 | /* | |
332 | * Get the response from the packet. This will abort with a | |
333 | * fatal error if the packet is corrupt. | |
334 | */ | |
335 | for (i = 0; i < 16; i++) | |
336 | response[i] = buffer_get_char(&buffer); | |
8efc0c15 | 337 | } |
5260325f | 338 | buffer_free(&buffer); |
c345cf9d | 339 | return success; |
5260325f | 340 | } |
8efc0c15 | 341 | |
2e73a022 | 342 | /* ask agent to sign data, returns -1 on error, 0 on success */ |
343 | int | |
344 | ssh_agent_sign(AuthenticationConnection *auth, | |
345 | Key *key, | |
346 | unsigned char **sigp, int *lenp, | |
347 | unsigned char *data, int datalen) | |
348 | { | |
349 | Buffer msg; | |
350 | unsigned char *blob; | |
351 | unsigned int blen; | |
352 | int type; | |
353 | int ret = -1; | |
354 | ||
355 | if (dsa_make_key_blob(key, &blob, &blen) == 0) | |
356 | return -1; | |
357 | ||
358 | buffer_init(&msg); | |
359 | buffer_put_char(&msg, SSH2_AGENTC_SIGN_REQUEST); | |
360 | buffer_put_string(&msg, blob, blen); | |
361 | buffer_put_string(&msg, data, datalen); | |
362 | xfree(blob); | |
363 | ||
364 | if (ssh_request_reply(auth, &msg, &msg) == 0) { | |
365 | buffer_free(&msg); | |
366 | return -1; | |
367 | } | |
368 | type = buffer_get_char(&msg); | |
369 | if (type == SSH_AGENT_FAILURE) { | |
370 | log("Agent admitted failure to sign using the key."); | |
371 | } else if (type != SSH2_AGENT_SIGN_RESPONSE) { | |
372 | fatal("Bad authentication response: %d", type); | |
373 | } else { | |
374 | ret = 0; | |
375 | *sigp = buffer_get_string(&msg, lenp); | |
376 | } | |
377 | buffer_free(&msg); | |
378 | return ret; | |
379 | } | |
380 | ||
4c8722d9 | 381 | /* Encode key for a message to the agent. */ |
382 | ||
383 | void | |
384 | ssh_encode_identity_rsa(Buffer *b, RSA *key, const char *comment) | |
385 | { | |
386 | buffer_clear(b); | |
387 | buffer_put_char(b, SSH_AGENTC_ADD_RSA_IDENTITY); | |
388 | buffer_put_int(b, BN_num_bits(key->n)); | |
389 | buffer_put_bignum(b, key->n); | |
390 | buffer_put_bignum(b, key->e); | |
391 | buffer_put_bignum(b, key->d); | |
392 | /* To keep within the protocol: p < q for ssh. in SSL p > q */ | |
393 | buffer_put_bignum(b, key->iqmp); /* ssh key->u */ | |
394 | buffer_put_bignum(b, key->q); /* ssh key->p, SSL key->q */ | |
395 | buffer_put_bignum(b, key->p); /* ssh key->q, SSL key->p */ | |
396 | buffer_put_string(b, comment, strlen(comment)); | |
397 | } | |
398 | ||
399 | void | |
400 | ssh_encode_identity_dsa(Buffer *b, DSA *key, const char *comment) | |
401 | { | |
402 | buffer_clear(b); | |
403 | buffer_put_char(b, SSH2_AGENTC_ADD_IDENTITY); | |
404 | buffer_put_cstring(b, KEX_DSS); | |
405 | buffer_put_bignum2(b, key->p); | |
406 | buffer_put_bignum2(b, key->q); | |
407 | buffer_put_bignum2(b, key->g); | |
408 | buffer_put_bignum2(b, key->pub_key); | |
409 | buffer_put_bignum2(b, key->priv_key); | |
410 | buffer_put_string(b, comment, strlen(comment)); | |
411 | } | |
412 | ||
aa3378df | 413 | /* |
414 | * Adds an identity to the authentication server. This call is not meant to | |
415 | * be used by normal applications. | |
416 | */ | |
8efc0c15 | 417 | |
6ae2364d | 418 | int |
4c8722d9 | 419 | ssh_add_identity(AuthenticationConnection *auth, Key *key, const char *comment) |
8efc0c15 | 420 | { |
2e73a022 | 421 | Buffer msg; |
c345cf9d | 422 | int type; |
5260325f | 423 | |
2e73a022 | 424 | buffer_init(&msg); |
4c8722d9 | 425 | |
426 | switch (key->type) { | |
427 | case KEY_RSA: | |
2e73a022 | 428 | ssh_encode_identity_rsa(&msg, key->rsa, comment); |
4c8722d9 | 429 | break; |
430 | case KEY_DSA: | |
2e73a022 | 431 | ssh_encode_identity_dsa(&msg, key->dsa, comment); |
4c8722d9 | 432 | break; |
433 | default: | |
2e73a022 | 434 | buffer_free(&msg); |
4c8722d9 | 435 | return 0; |
436 | break; | |
437 | } | |
2e73a022 | 438 | if (ssh_request_reply(auth, &msg, &msg) == 0) { |
439 | buffer_free(&msg); | |
5260325f | 440 | return 0; |
441 | } | |
2e73a022 | 442 | type = buffer_get_char(&msg); |
443 | buffer_free(&msg); | |
c345cf9d | 444 | return decode_reply(type); |
5260325f | 445 | } |
446 | ||
aa3378df | 447 | /* |
448 | * Removes an identity from the authentication server. This call is not | |
449 | * meant to be used by normal applications. | |
450 | */ | |
8efc0c15 | 451 | |
6ae2364d | 452 | int |
2e73a022 | 453 | ssh_remove_identity(AuthenticationConnection *auth, Key *key) |
8efc0c15 | 454 | { |
2e73a022 | 455 | Buffer msg; |
c345cf9d | 456 | int type; |
2e73a022 | 457 | unsigned char *blob; |
458 | unsigned int blen; | |
459 | ||
460 | buffer_init(&msg); | |
461 | ||
462 | if (key->type == KEY_RSA) { | |
463 | buffer_put_char(&msg, SSH_AGENTC_REMOVE_RSA_IDENTITY); | |
464 | buffer_put_int(&msg, BN_num_bits(key->rsa->n)); | |
465 | buffer_put_bignum(&msg, key->rsa->e); | |
466 | buffer_put_bignum(&msg, key->rsa->n); | |
467 | } else if (key->type == KEY_DSA) { | |
468 | dsa_make_key_blob(key, &blob, &blen); | |
469 | buffer_put_char(&msg, SSH2_AGENTC_REMOVE_IDENTITY); | |
470 | buffer_put_string(&msg, blob, blen); | |
471 | xfree(blob); | |
472 | } else { | |
473 | buffer_free(&msg); | |
5260325f | 474 | return 0; |
475 | } | |
2e73a022 | 476 | if (ssh_request_reply(auth, &msg, &msg) == 0) { |
477 | buffer_free(&msg); | |
478 | return 0; | |
479 | } | |
480 | type = buffer_get_char(&msg); | |
481 | buffer_free(&msg); | |
c345cf9d | 482 | return decode_reply(type); |
5260325f | 483 | } |
484 | ||
aa3378df | 485 | /* |
486 | * Removes all identities from the agent. This call is not meant to be used | |
487 | * by normal applications. | |
488 | */ | |
8efc0c15 | 489 | |
6ae2364d | 490 | int |
2e73a022 | 491 | ssh_remove_all_identities(AuthenticationConnection *auth, int version) |
8efc0c15 | 492 | { |
2e73a022 | 493 | Buffer msg; |
c345cf9d | 494 | int type; |
2e73a022 | 495 | int code = (version==1) ? |
496 | SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES : | |
497 | SSH2_AGENTC_REMOVE_ALL_IDENTITIES; | |
5260325f | 498 | |
2e73a022 | 499 | buffer_init(&msg); |
500 | buffer_put_char(&msg, code); | |
5260325f | 501 | |
2e73a022 | 502 | if (ssh_request_reply(auth, &msg, &msg) == 0) { |
503 | buffer_free(&msg); | |
5260325f | 504 | return 0; |
505 | } | |
2e73a022 | 506 | type = buffer_get_char(&msg); |
507 | buffer_free(&msg); | |
c345cf9d | 508 | return decode_reply(type); |
089fbbd2 | 509 | } |
510 | ||
089fbbd2 | 511 | int |
c345cf9d | 512 | decode_reply(int type) |
089fbbd2 | 513 | { |
5260325f | 514 | switch (type) { |
515 | case SSH_AGENT_FAILURE: | |
c345cf9d | 516 | log("SSH_AGENT_FAILURE"); |
5260325f | 517 | return 0; |
518 | case SSH_AGENT_SUCCESS: | |
5260325f | 519 | return 1; |
520 | default: | |
089fbbd2 | 521 | fatal("Bad response from authentication agent: %d", type); |
8efc0c15 | 522 | } |
5260325f | 523 | /* NOTREACHED */ |
524 | return 0; | |
525 | } |