]>
Commit | Line | Data |
---|---|---|
8efc0c15 | 1 | /* |
5260325f | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * Created: Sat Mar 18 22:15:47 1995 ylo | |
6 | * Code to connect to a remote host, and to perform the client side of the | |
7 | * login (authentication) dialog. | |
8ce64345 | 8 | * |
9 | * SSH2 support added by Markus Friedl. | |
5260325f | 10 | */ |
8efc0c15 | 11 | |
12 | #include "includes.h" | |
8ce64345 | 13 | RCSID("$OpenBSD: sshconnect.c,v 1.61 2000/04/04 21:37:27 markus Exp $"); |
8efc0c15 | 14 | |
5881cd60 | 15 | #ifdef HAVE_OPENSSL |
8ce64345 | 16 | #include <openssl/bn.h> |
4fe2af09 | 17 | #include <openssl/rsa.h> |
18 | #include <openssl/dsa.h> | |
5881cd60 | 19 | #include <openssl/md5.h> |
20 | #endif | |
21 | #ifdef HAVE_SSL | |
8ce64345 | 22 | #include <ssl/bn.h> |
4fe2af09 | 23 | #include <ssl/rsa.h> |
24 | #include <ssl/dsa.h> | |
5881cd60 | 25 | #include <ssl/md5.h> |
26 | #endif | |
27 | ||
8efc0c15 | 28 | #include "xmalloc.h" |
29 | #include "rsa.h" | |
30 | #include "ssh.h" | |
8ce64345 | 31 | #include "buffer.h" |
8efc0c15 | 32 | #include "packet.h" |
33 | #include "authfd.h" | |
34 | #include "cipher.h" | |
35 | #include "mpaux.h" | |
36 | #include "uidswap.h" | |
37 | #include "compat.h" | |
6fa724bc | 38 | #include "readconf.h" |
8ce64345 | 39 | |
40 | #include "bufaux.h" | |
41 | ||
42 | #include "ssh2.h" | |
43 | #include "kex.h" | |
44 | #include "myproposal.h" | |
4fe2af09 | 45 | #include "key.h" |
8ce64345 | 46 | #include "dsa.h" |
4fe2af09 | 47 | #include "hostfile.h" |
8efc0c15 | 48 | |
49 | /* Session id for the current session. */ | |
50 | unsigned char session_id[16]; | |
51 | ||
7b2ea3a1 | 52 | /* authentications supported by server */ |
53 | unsigned int supported_authentications; | |
54 | ||
8ce64345 | 55 | static char *client_version_string = NULL; |
56 | static char *server_version_string = NULL; | |
57 | ||
57112b5a | 58 | extern Options options; |
48e671d5 | 59 | extern char *__progname; |
57112b5a | 60 | |
5260325f | 61 | /* |
62 | * Connect to the given ssh server using a proxy command. | |
63 | */ | |
8efc0c15 | 64 | int |
57112b5a | 65 | ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid, |
8efc0c15 | 66 | const char *proxy_command) |
67 | { | |
5260325f | 68 | Buffer command; |
69 | const char *cp; | |
70 | char *command_string; | |
71 | int pin[2], pout[2]; | |
72 | int pid; | |
48e671d5 | 73 | char strport[NI_MAXSERV]; |
5260325f | 74 | |
75 | /* Convert the port number into a string. */ | |
48e671d5 | 76 | snprintf(strport, sizeof strport, "%hu", port); |
5260325f | 77 | |
78 | /* Build the final command string in the buffer by making the | |
79 | appropriate substitutions to the given proxy command. */ | |
80 | buffer_init(&command); | |
81 | for (cp = proxy_command; *cp; cp++) { | |
82 | if (cp[0] == '%' && cp[1] == '%') { | |
83 | buffer_append(&command, "%", 1); | |
84 | cp++; | |
85 | continue; | |
86 | } | |
87 | if (cp[0] == '%' && cp[1] == 'h') { | |
88 | buffer_append(&command, host, strlen(host)); | |
89 | cp++; | |
90 | continue; | |
91 | } | |
92 | if (cp[0] == '%' && cp[1] == 'p') { | |
48e671d5 | 93 | buffer_append(&command, strport, strlen(strport)); |
5260325f | 94 | cp++; |
95 | continue; | |
96 | } | |
97 | buffer_append(&command, cp, 1); | |
8efc0c15 | 98 | } |
5260325f | 99 | buffer_append(&command, "\0", 1); |
100 | ||
101 | /* Get the final command string. */ | |
102 | command_string = buffer_ptr(&command); | |
103 | ||
104 | /* Create pipes for communicating with the proxy. */ | |
105 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
106 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
107 | strerror(errno)); | |
108 | ||
109 | debug("Executing proxy command: %.500s", command_string); | |
110 | ||
111 | /* Fork and execute the proxy command. */ | |
112 | if ((pid = fork()) == 0) { | |
113 | char *argv[10]; | |
114 | ||
115 | /* Child. Permanently give up superuser privileges. */ | |
116 | permanently_set_uid(original_real_uid); | |
117 | ||
118 | /* Redirect stdin and stdout. */ | |
119 | close(pin[1]); | |
120 | if (pin[0] != 0) { | |
121 | if (dup2(pin[0], 0) < 0) | |
122 | perror("dup2 stdin"); | |
123 | close(pin[0]); | |
124 | } | |
125 | close(pout[0]); | |
126 | if (dup2(pout[1], 1) < 0) | |
127 | perror("dup2 stdout"); | |
128 | /* Cannot be 1 because pin allocated two descriptors. */ | |
129 | close(pout[1]); | |
130 | ||
131 | /* Stderr is left as it is so that error messages get | |
132 | printed on the user's terminal. */ | |
133 | argv[0] = "/bin/sh"; | |
134 | argv[1] = "-c"; | |
135 | argv[2] = command_string; | |
136 | argv[3] = NULL; | |
137 | ||
138 | /* Execute the proxy command. Note that we gave up any | |
139 | extra privileges above. */ | |
140 | execv("/bin/sh", argv); | |
141 | perror("/bin/sh"); | |
142 | exit(1); | |
8efc0c15 | 143 | } |
5260325f | 144 | /* Parent. */ |
145 | if (pid < 0) | |
146 | fatal("fork failed: %.100s", strerror(errno)); | |
147 | ||
148 | /* Close child side of the descriptors. */ | |
149 | close(pin[0]); | |
150 | close(pout[1]); | |
151 | ||
152 | /* Free the command name. */ | |
153 | buffer_free(&command); | |
154 | ||
155 | /* Set the connection file descriptors. */ | |
156 | packet_set_connection(pout[0], pin[1]); | |
8efc0c15 | 157 | |
5260325f | 158 | return 1; |
159 | } | |
8efc0c15 | 160 | |
5260325f | 161 | /* |
162 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
163 | */ | |
164 | int | |
48e671d5 | 165 | ssh_create_socket(uid_t original_real_uid, int privileged, int family) |
8efc0c15 | 166 | { |
5260325f | 167 | int sock; |
168 | ||
aa3378df | 169 | /* |
170 | * If we are running as root and want to connect to a privileged | |
171 | * port, bind our own socket to a privileged port. | |
172 | */ | |
5260325f | 173 | if (privileged) { |
174 | int p = IPPORT_RESERVED - 1; | |
48e671d5 | 175 | sock = rresvport_af(&p, family); |
5260325f | 176 | if (sock < 0) |
c8d54615 | 177 | error("rresvport: af=%d %.100s", family, strerror(errno)); |
178 | else | |
179 | debug("Allocated local port %d.", p); | |
5260325f | 180 | } else { |
95f1eccc | 181 | /* |
182 | * Just create an ordinary socket on arbitrary port. We use | |
183 | * the user's uid to create the socket. | |
184 | */ | |
5260325f | 185 | temporarily_use_uid(original_real_uid); |
48e671d5 | 186 | sock = socket(family, SOCK_STREAM, 0); |
5260325f | 187 | if (sock < 0) |
48e671d5 | 188 | error("socket: %.100s", strerror(errno)); |
5260325f | 189 | restore_uid(); |
190 | } | |
191 | return sock; | |
8efc0c15 | 192 | } |
193 | ||
5260325f | 194 | /* |
48e671d5 | 195 | * Opens a TCP/IP connection to the remote server on the given host. |
196 | * The address of the remote host will be returned in hostaddr. | |
197 | * If port is 0, the default port will be used. If anonymous is zero, | |
5260325f | 198 | * a privileged port will be allocated to make the connection. |
199 | * This requires super-user privileges if anonymous is false. | |
200 | * Connection_attempts specifies the maximum number of tries (one per | |
201 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
202 | * and %p substituted for host and port, respectively) to use to contact | |
203 | * the daemon. | |
204 | */ | |
205 | int | |
48e671d5 | 206 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, |
57112b5a | 207 | u_short port, int connection_attempts, |
5260325f | 208 | int anonymous, uid_t original_real_uid, |
209 | const char *proxy_command) | |
8efc0c15 | 210 | { |
48e671d5 | 211 | int sock = -1, attempt; |
5260325f | 212 | struct servent *sp; |
48e671d5 | 213 | struct addrinfo hints, *ai, *aitop; |
214 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
215 | int gaierr; | |
5260325f | 216 | struct linger linger; |
217 | ||
218 | debug("ssh_connect: getuid %d geteuid %d anon %d", | |
219 | (int) getuid(), (int) geteuid(), anonymous); | |
220 | ||
221 | /* Get default port if port has not been set. */ | |
222 | if (port == 0) { | |
223 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
224 | if (sp) | |
225 | port = ntohs(sp->s_port); | |
226 | else | |
227 | port = SSH_DEFAULT_PORT; | |
8efc0c15 | 228 | } |
5260325f | 229 | /* If a proxy command is given, connect using it. */ |
230 | if (proxy_command != NULL) | |
231 | return ssh_proxy_connect(host, port, original_real_uid, proxy_command); | |
232 | ||
233 | /* No proxy command. */ | |
234 | ||
48e671d5 | 235 | memset(&hints, 0, sizeof(hints)); |
236 | hints.ai_family = IPv4or6; | |
237 | hints.ai_socktype = SOCK_STREAM; | |
238 | snprintf(strport, sizeof strport, "%d", port); | |
239 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) | |
240 | fatal("%s: %.100s: %s", __progname, host, | |
241 | gai_strerror(gaierr)); | |
5260325f | 242 | |
95f1eccc | 243 | /* |
244 | * Try to connect several times. On some machines, the first time | |
245 | * will sometimes fail. In general socket code appears to behave | |
246 | * quite magically on many machines. | |
247 | */ | |
5260325f | 248 | for (attempt = 0; attempt < connection_attempts; attempt++) { |
249 | if (attempt > 0) | |
250 | debug("Trying again..."); | |
251 | ||
48e671d5 | 252 | /* Loop through addresses for this host, and try each one in |
253 | sequence until the connection succeeds. */ | |
254 | for (ai = aitop; ai; ai = ai->ai_next) { | |
255 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
256 | continue; | |
257 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
258 | ntop, sizeof(ntop), strport, sizeof(strport), | |
259 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
260 | error("ssh_connect: getnameinfo failed"); | |
261 | continue; | |
262 | } | |
263 | debug("Connecting to %.200s [%.100s] port %s.", | |
264 | host, ntop, strport); | |
265 | ||
266 | /* Create a socket for connecting. */ | |
267 | sock = ssh_create_socket(original_real_uid, | |
268 | !anonymous && geteuid() == 0 && port < IPPORT_RESERVED, | |
269 | ai->ai_family); | |
270 | if (sock < 0) | |
271 | continue; | |
272 | ||
273 | /* Connect to the host. We use the user's uid in the | |
274 | * hope that it will help with tcp_wrappers showing | |
275 | * the remote uid as root. | |
aa3378df | 276 | */ |
5260325f | 277 | temporarily_use_uid(original_real_uid); |
48e671d5 | 278 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { |
279 | /* Successful connection. */ | |
280 | memcpy(hostaddr, ai->ai_addr, sizeof(*(ai->ai_addr))); | |
5260325f | 281 | restore_uid(); |
282 | break; | |
48e671d5 | 283 | } else { |
5260325f | 284 | debug("connect: %.100s", strerror(errno)); |
285 | restore_uid(); | |
aa3378df | 286 | /* |
287 | * Close the failed socket; there appear to | |
288 | * be some problems when reusing a socket for | |
289 | * which connect() has already returned an | |
290 | * error. | |
291 | */ | |
5260325f | 292 | shutdown(sock, SHUT_RDWR); |
293 | close(sock); | |
294 | } | |
8efc0c15 | 295 | } |
48e671d5 | 296 | if (ai) |
297 | break; /* Successful connection. */ | |
8efc0c15 | 298 | |
5260325f | 299 | /* Sleep a moment before retrying. */ |
300 | sleep(1); | |
301 | } | |
48e671d5 | 302 | |
303 | freeaddrinfo(aitop); | |
304 | ||
5260325f | 305 | /* Return failure if we didn't get a successful connection. */ |
306 | if (attempt >= connection_attempts) | |
307 | return 0; | |
8efc0c15 | 308 | |
5260325f | 309 | debug("Connection established."); |
8efc0c15 | 310 | |
aa3378df | 311 | /* |
312 | * Set socket options. We would like the socket to disappear as soon | |
313 | * as it has been closed for whatever reason. | |
314 | */ | |
315 | /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 316 | linger.l_onoff = 1; |
317 | linger.l_linger = 5; | |
318 | setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
8efc0c15 | 319 | |
5260325f | 320 | /* Set the connection. */ |
321 | packet_set_connection(sock, sock); | |
8efc0c15 | 322 | |
5260325f | 323 | return 1; |
8efc0c15 | 324 | } |
325 | ||
5260325f | 326 | /* |
327 | * Checks if the user has an authentication agent, and if so, tries to | |
328 | * authenticate using the agent. | |
329 | */ | |
8efc0c15 | 330 | int |
331 | try_agent_authentication() | |
332 | { | |
5260325f | 333 | int status, type; |
334 | char *comment; | |
335 | AuthenticationConnection *auth; | |
336 | unsigned char response[16]; | |
337 | unsigned int i; | |
338 | BIGNUM *e, *n, *challenge; | |
339 | ||
340 | /* Get connection to the agent. */ | |
341 | auth = ssh_get_authentication_connection(); | |
342 | if (!auth) | |
343 | return 0; | |
344 | ||
345 | e = BN_new(); | |
346 | n = BN_new(); | |
347 | challenge = BN_new(); | |
348 | ||
349 | /* Loop through identities served by the agent. */ | |
350 | for (status = ssh_get_first_identity(auth, e, n, &comment); | |
351 | status; | |
352 | status = ssh_get_next_identity(auth, e, n, &comment)) { | |
353 | int plen, clen; | |
354 | ||
355 | /* Try this identity. */ | |
356 | debug("Trying RSA authentication via agent with '%.100s'", comment); | |
357 | xfree(comment); | |
358 | ||
359 | /* Tell the server that we are willing to authenticate using this key. */ | |
360 | packet_start(SSH_CMSG_AUTH_RSA); | |
361 | packet_put_bignum(n); | |
362 | packet_send(); | |
363 | packet_write_wait(); | |
364 | ||
365 | /* Wait for server's response. */ | |
366 | type = packet_read(&plen); | |
367 | ||
368 | /* The server sends failure if it doesn\'t like our key or | |
369 | does not support RSA authentication. */ | |
370 | if (type == SSH_SMSG_FAILURE) { | |
371 | debug("Server refused our key."); | |
372 | continue; | |
373 | } | |
374 | /* Otherwise it should have sent a challenge. */ | |
375 | if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) | |
376 | packet_disconnect("Protocol error during RSA authentication: %d", | |
377 | type); | |
8efc0c15 | 378 | |
5260325f | 379 | packet_get_bignum(challenge, &clen); |
8efc0c15 | 380 | |
5260325f | 381 | packet_integrity_check(plen, clen, type); |
8efc0c15 | 382 | |
5260325f | 383 | debug("Received RSA challenge from server."); |
384 | ||
385 | /* Ask the agent to decrypt the challenge. */ | |
386 | if (!ssh_decrypt_challenge(auth, e, n, challenge, | |
387 | session_id, 1, response)) { | |
388 | /* The agent failed to authenticate this identifier although it | |
389 | advertised it supports this. Just return a wrong value. */ | |
390 | log("Authentication agent failed to decrypt challenge."); | |
391 | memset(response, 0, sizeof(response)); | |
392 | } | |
393 | debug("Sending response to RSA challenge."); | |
394 | ||
395 | /* Send the decrypted challenge back to the server. */ | |
396 | packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); | |
397 | for (i = 0; i < 16; i++) | |
398 | packet_put_char(response[i]); | |
399 | packet_send(); | |
400 | packet_write_wait(); | |
401 | ||
402 | /* Wait for response from the server. */ | |
403 | type = packet_read(&plen); | |
404 | ||
405 | /* The server returns success if it accepted the authentication. */ | |
406 | if (type == SSH_SMSG_SUCCESS) { | |
407 | debug("RSA authentication accepted by server."); | |
408 | BN_clear_free(e); | |
409 | BN_clear_free(n); | |
410 | BN_clear_free(challenge); | |
411 | return 1; | |
412 | } | |
413 | /* Otherwise it should return failure. */ | |
414 | if (type != SSH_SMSG_FAILURE) | |
415 | packet_disconnect("Protocol error waiting RSA auth response: %d", | |
416 | type); | |
417 | } | |
418 | ||
419 | BN_clear_free(e); | |
420 | BN_clear_free(n); | |
421 | BN_clear_free(challenge); | |
8efc0c15 | 422 | |
5260325f | 423 | debug("RSA authentication using agent refused."); |
424 | return 0; | |
425 | } | |
8efc0c15 | 426 | |
5260325f | 427 | /* |
428 | * Computes the proper response to a RSA challenge, and sends the response to | |
429 | * the server. | |
430 | */ | |
8efc0c15 | 431 | void |
5260325f | 432 | respond_to_rsa_challenge(BIGNUM * challenge, RSA * prv) |
8efc0c15 | 433 | { |
5260325f | 434 | unsigned char buf[32], response[16]; |
435 | MD5_CTX md; | |
436 | int i, len; | |
437 | ||
438 | /* Decrypt the challenge using the private key. */ | |
439 | rsa_private_decrypt(challenge, challenge, prv); | |
440 | ||
441 | /* Compute the response. */ | |
442 | /* The response is MD5 of decrypted challenge plus session id. */ | |
443 | len = BN_num_bytes(challenge); | |
444 | if (len <= 0 || len > sizeof(buf)) | |
445 | packet_disconnect("respond_to_rsa_challenge: bad challenge length %d", | |
446 | len); | |
447 | ||
448 | memset(buf, 0, sizeof(buf)); | |
449 | BN_bn2bin(challenge, buf + sizeof(buf) - len); | |
450 | MD5_Init(&md); | |
451 | MD5_Update(&md, buf, 32); | |
452 | MD5_Update(&md, session_id, 16); | |
453 | MD5_Final(response, &md); | |
454 | ||
455 | debug("Sending response to host key RSA challenge."); | |
456 | ||
457 | /* Send the response back to the server. */ | |
458 | packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); | |
459 | for (i = 0; i < 16; i++) | |
460 | packet_put_char(response[i]); | |
461 | packet_send(); | |
462 | packet_write_wait(); | |
8efc0c15 | 463 | |
5260325f | 464 | memset(buf, 0, sizeof(buf)); |
465 | memset(response, 0, sizeof(response)); | |
466 | memset(&md, 0, sizeof(md)); | |
467 | } | |
8efc0c15 | 468 | |
5260325f | 469 | /* |
470 | * Checks if the user has authentication file, and if so, tries to authenticate | |
471 | * the user using it. | |
472 | */ | |
8efc0c15 | 473 | int |
57112b5a | 474 | try_rsa_authentication(const char *authfile) |
8efc0c15 | 475 | { |
5260325f | 476 | BIGNUM *challenge; |
477 | RSA *private_key; | |
478 | RSA *public_key; | |
479 | char *passphrase, *comment; | |
480 | int type, i; | |
481 | int plen, clen; | |
482 | ||
483 | /* Try to load identification for the authentication key. */ | |
484 | public_key = RSA_new(); | |
485 | if (!load_public_key(authfile, public_key, &comment)) { | |
486 | RSA_free(public_key); | |
57112b5a | 487 | /* Could not load it. Fail. */ |
488 | return 0; | |
8efc0c15 | 489 | } |
5260325f | 490 | debug("Trying RSA authentication with key '%.100s'", comment); |
491 | ||
492 | /* Tell the server that we are willing to authenticate using this key. */ | |
493 | packet_start(SSH_CMSG_AUTH_RSA); | |
494 | packet_put_bignum(public_key->n); | |
495 | packet_send(); | |
496 | packet_write_wait(); | |
497 | ||
498 | /* We no longer need the public key. */ | |
499 | RSA_free(public_key); | |
500 | ||
501 | /* Wait for server's response. */ | |
502 | type = packet_read(&plen); | |
503 | ||
aa3378df | 504 | /* |
505 | * The server responds with failure if it doesn\'t like our key or | |
506 | * doesn\'t support RSA authentication. | |
507 | */ | |
5260325f | 508 | if (type == SSH_SMSG_FAILURE) { |
509 | debug("Server refused our key."); | |
510 | xfree(comment); | |
57112b5a | 511 | return 0; |
8efc0c15 | 512 | } |
5260325f | 513 | /* Otherwise, the server should respond with a challenge. */ |
514 | if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) | |
515 | packet_disconnect("Protocol error during RSA authentication: %d", type); | |
516 | ||
517 | /* Get the challenge from the packet. */ | |
518 | challenge = BN_new(); | |
519 | packet_get_bignum(challenge, &clen); | |
520 | ||
521 | packet_integrity_check(plen, clen, type); | |
522 | ||
523 | debug("Received RSA challenge from server."); | |
524 | ||
525 | private_key = RSA_new(); | |
aa3378df | 526 | /* |
527 | * Load the private key. Try first with empty passphrase; if it | |
528 | * fails, ask for a passphrase. | |
529 | */ | |
5260325f | 530 | if (!load_private_key(authfile, "", private_key, NULL)) { |
531 | char buf[300]; | |
532 | snprintf(buf, sizeof buf, "Enter passphrase for RSA key '%.100s': ", | |
a408af76 | 533 | comment); |
5260325f | 534 | if (!options.batch_mode) |
535 | passphrase = read_passphrase(buf, 0); | |
536 | else { | |
537 | debug("Will not query passphrase for %.100s in batch mode.", | |
538 | comment); | |
539 | passphrase = xstrdup(""); | |
540 | } | |
8efc0c15 | 541 | |
5260325f | 542 | /* Load the authentication file using the pasphrase. */ |
543 | if (!load_private_key(authfile, passphrase, private_key, NULL)) { | |
544 | memset(passphrase, 0, strlen(passphrase)); | |
545 | xfree(passphrase); | |
546 | error("Bad passphrase."); | |
547 | ||
548 | /* Send a dummy response packet to avoid protocol error. */ | |
549 | packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); | |
550 | for (i = 0; i < 16; i++) | |
551 | packet_put_char(0); | |
552 | packet_send(); | |
553 | packet_write_wait(); | |
554 | ||
555 | /* Expect the server to reject it... */ | |
556 | packet_read_expect(&plen, SSH_SMSG_FAILURE); | |
557 | xfree(comment); | |
558 | return 0; | |
559 | } | |
560 | /* Destroy the passphrase. */ | |
561 | memset(passphrase, 0, strlen(passphrase)); | |
562 | xfree(passphrase); | |
563 | } | |
564 | /* We no longer need the comment. */ | |
565 | xfree(comment); | |
566 | ||
567 | /* Compute and send a response to the challenge. */ | |
568 | respond_to_rsa_challenge(challenge, private_key); | |
569 | ||
570 | /* Destroy the private key. */ | |
571 | RSA_free(private_key); | |
8efc0c15 | 572 | |
5260325f | 573 | /* We no longer need the challenge. */ |
574 | BN_clear_free(challenge); | |
575 | ||
576 | /* Wait for response from the server. */ | |
577 | type = packet_read(&plen); | |
578 | if (type == SSH_SMSG_SUCCESS) { | |
579 | debug("RSA authentication accepted by server."); | |
580 | return 1; | |
581 | } | |
582 | if (type != SSH_SMSG_FAILURE) | |
583 | packet_disconnect("Protocol error waiting RSA auth response: %d", type); | |
584 | debug("RSA authentication refused."); | |
585 | return 0; | |
586 | } | |
8efc0c15 | 587 | |
5260325f | 588 | /* |
589 | * Tries to authenticate the user using combined rhosts or /etc/hosts.equiv | |
590 | * authentication and RSA host authentication. | |
591 | */ | |
8efc0c15 | 592 | int |
5260325f | 593 | try_rhosts_rsa_authentication(const char *local_user, RSA * host_key) |
8efc0c15 | 594 | { |
5260325f | 595 | int type; |
596 | BIGNUM *challenge; | |
597 | int plen, clen; | |
598 | ||
599 | debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication."); | |
600 | ||
601 | /* Tell the server that we are willing to authenticate using this key. */ | |
602 | packet_start(SSH_CMSG_AUTH_RHOSTS_RSA); | |
603 | packet_put_string(local_user, strlen(local_user)); | |
604 | packet_put_int(BN_num_bits(host_key->n)); | |
605 | packet_put_bignum(host_key->e); | |
606 | packet_put_bignum(host_key->n); | |
607 | packet_send(); | |
608 | packet_write_wait(); | |
609 | ||
610 | /* Wait for server's response. */ | |
611 | type = packet_read(&plen); | |
612 | ||
613 | /* The server responds with failure if it doesn't admit our | |
614 | .rhosts authentication or doesn't know our host key. */ | |
615 | if (type == SSH_SMSG_FAILURE) { | |
616 | debug("Server refused our rhosts authentication or host key."); | |
617 | return 0; | |
618 | } | |
619 | /* Otherwise, the server should respond with a challenge. */ | |
620 | if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) | |
621 | packet_disconnect("Protocol error during RSA authentication: %d", type); | |
622 | ||
623 | /* Get the challenge from the packet. */ | |
624 | challenge = BN_new(); | |
625 | packet_get_bignum(challenge, &clen); | |
626 | ||
627 | packet_integrity_check(plen, clen, type); | |
628 | ||
629 | debug("Received RSA challenge for host key from server."); | |
630 | ||
631 | /* Compute a response to the challenge. */ | |
632 | respond_to_rsa_challenge(challenge, host_key); | |
633 | ||
634 | /* We no longer need the challenge. */ | |
635 | BN_clear_free(challenge); | |
636 | ||
637 | /* Wait for response from the server. */ | |
638 | type = packet_read(&plen); | |
639 | if (type == SSH_SMSG_SUCCESS) { | |
640 | debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server."); | |
641 | return 1; | |
642 | } | |
643 | if (type != SSH_SMSG_FAILURE) | |
644 | packet_disconnect("Protocol error waiting RSA auth response: %d", type); | |
645 | debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused."); | |
646 | return 0; | |
8efc0c15 | 647 | } |
648 | ||
649 | #ifdef KRB4 | |
5260325f | 650 | int |
651 | try_kerberos_authentication() | |
8efc0c15 | 652 | { |
5260325f | 653 | KTEXT_ST auth; /* Kerberos data */ |
654 | char *reply; | |
655 | char inst[INST_SZ]; | |
656 | char *realm; | |
657 | CREDENTIALS cred; | |
658 | int r, type, plen; | |
610cd5c6 | 659 | socklen_t slen; |
5260325f | 660 | Key_schedule schedule; |
661 | u_long checksum, cksum; | |
662 | MSG_DAT msg_data; | |
663 | struct sockaddr_in local, foreign; | |
664 | struct stat st; | |
665 | ||
666 | /* Don't do anything if we don't have any tickets. */ | |
667 | if (stat(tkt_string(), &st) < 0) | |
668 | return 0; | |
669 | ||
670 | strncpy(inst, (char *) krb_get_phost(get_canonical_hostname()), INST_SZ); | |
671 | ||
672 | realm = (char *) krb_realmofhost(get_canonical_hostname()); | |
673 | if (!realm) { | |
674 | debug("Kerberos V4: no realm for %s", get_canonical_hostname()); | |
675 | return 0; | |
676 | } | |
677 | /* This can really be anything. */ | |
678 | checksum = (u_long) getpid(); | |
679 | ||
680 | r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum); | |
681 | if (r != KSUCCESS) { | |
682 | debug("Kerberos V4 krb_mk_req failed: %s", krb_err_txt[r]); | |
683 | return 0; | |
684 | } | |
685 | /* Get session key to decrypt the server's reply with. */ | |
686 | r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred); | |
687 | if (r != KSUCCESS) { | |
688 | debug("get_cred failed: %s", krb_err_txt[r]); | |
689 | return 0; | |
690 | } | |
691 | des_key_sched((des_cblock *) cred.session, schedule); | |
692 | ||
693 | /* Send authentication info to server. */ | |
694 | packet_start(SSH_CMSG_AUTH_KERBEROS); | |
695 | packet_put_string((char *) auth.dat, auth.length); | |
696 | packet_send(); | |
697 | packet_write_wait(); | |
698 | ||
699 | /* Zero the buffer. */ | |
700 | (void) memset(auth.dat, 0, MAX_KTXT_LEN); | |
701 | ||
610cd5c6 | 702 | slen = sizeof(local); |
5260325f | 703 | memset(&local, 0, sizeof(local)); |
704 | if (getsockname(packet_get_connection_in(), | |
610cd5c6 | 705 | (struct sockaddr *) & local, &slen) < 0) |
5260325f | 706 | debug("getsockname failed: %s", strerror(errno)); |
707 | ||
610cd5c6 | 708 | slen = sizeof(foreign); |
5260325f | 709 | memset(&foreign, 0, sizeof(foreign)); |
710 | if (getpeername(packet_get_connection_in(), | |
610cd5c6 | 711 | (struct sockaddr *) & foreign, &slen) < 0) { |
5260325f | 712 | debug("getpeername failed: %s", strerror(errno)); |
713 | fatal_cleanup(); | |
714 | } | |
715 | /* Get server reply. */ | |
716 | type = packet_read(&plen); | |
717 | switch (type) { | |
718 | case SSH_SMSG_FAILURE: | |
719 | /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */ | |
720 | debug("Kerberos V4 authentication failed."); | |
721 | return 0; | |
722 | break; | |
723 | ||
724 | case SSH_SMSG_AUTH_KERBEROS_RESPONSE: | |
725 | /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */ | |
726 | debug("Kerberos V4 authentication accepted."); | |
727 | ||
728 | /* Get server's response. */ | |
729 | reply = packet_get_string((unsigned int *) &auth.length); | |
730 | memcpy(auth.dat, reply, auth.length); | |
731 | xfree(reply); | |
732 | ||
733 | packet_integrity_check(plen, 4 + auth.length, type); | |
734 | ||
aa3378df | 735 | /* |
736 | * If his response isn't properly encrypted with the session | |
737 | * key, and the decrypted checksum fails to match, he's | |
738 | * bogus. Bail out. | |
739 | */ | |
5260325f | 740 | r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session, |
741 | &foreign, &local, &msg_data); | |
742 | if (r != KSUCCESS) { | |
743 | debug("Kerberos V4 krb_rd_priv failed: %s", krb_err_txt[r]); | |
744 | packet_disconnect("Kerberos V4 challenge failed!"); | |
745 | } | |
746 | /* Fetch the (incremented) checksum that we supplied in the request. */ | |
747 | (void) memcpy((char *) &cksum, (char *) msg_data.app_data, sizeof(cksum)); | |
748 | cksum = ntohl(cksum); | |
749 | ||
750 | /* If it matches, we're golden. */ | |
751 | if (cksum == checksum + 1) { | |
752 | debug("Kerberos V4 challenge successful."); | |
753 | return 1; | |
754 | } else | |
755 | packet_disconnect("Kerberos V4 challenge failed!"); | |
756 | break; | |
757 | ||
758 | default: | |
759 | packet_disconnect("Protocol error on Kerberos V4 response: %d", type); | |
760 | } | |
761 | return 0; | |
8efc0c15 | 762 | } |
5260325f | 763 | |
8efc0c15 | 764 | #endif /* KRB4 */ |
765 | ||
766 | #ifdef AFS | |
5260325f | 767 | int |
768 | send_kerberos_tgt() | |
8efc0c15 | 769 | { |
5260325f | 770 | CREDENTIALS *creds; |
771 | char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ]; | |
772 | int r, type, plen; | |
610cd5c6 | 773 | char buffer[8192]; |
5260325f | 774 | struct stat st; |
775 | ||
776 | /* Don't do anything if we don't have any tickets. */ | |
777 | if (stat(tkt_string(), &st) < 0) | |
778 | return 0; | |
779 | ||
780 | creds = xmalloc(sizeof(*creds)); | |
781 | ||
782 | if ((r = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm)) != KSUCCESS) { | |
783 | debug("Kerberos V4 tf_fullname failed: %s", krb_err_txt[r]); | |
784 | return 0; | |
785 | } | |
786 | if ((r = krb_get_cred("krbtgt", prealm, prealm, creds)) != GC_OK) { | |
787 | debug("Kerberos V4 get_cred failed: %s", krb_err_txt[r]); | |
788 | return 0; | |
789 | } | |
790 | if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) { | |
791 | debug("Kerberos V4 ticket expired: %s", TKT_FILE); | |
792 | return 0; | |
793 | } | |
610cd5c6 | 794 | creds_to_radix(creds, (unsigned char *)buffer); |
5260325f | 795 | xfree(creds); |
796 | ||
797 | packet_start(SSH_CMSG_HAVE_KERBEROS_TGT); | |
610cd5c6 | 798 | packet_put_string(buffer, strlen(buffer)); |
5260325f | 799 | packet_send(); |
800 | packet_write_wait(); | |
801 | ||
802 | type = packet_read(&plen); | |
803 | ||
804 | if (type == SSH_SMSG_FAILURE) | |
805 | debug("Kerberos TGT for realm %s rejected.", prealm); | |
806 | else if (type != SSH_SMSG_SUCCESS) | |
807 | packet_disconnect("Protocol error on Kerberos TGT response: %d", type); | |
808 | ||
809 | return 1; | |
8efc0c15 | 810 | } |
811 | ||
5260325f | 812 | void |
813 | send_afs_tokens(void) | |
8efc0c15 | 814 | { |
5260325f | 815 | CREDENTIALS creds; |
816 | struct ViceIoctl parms; | |
817 | struct ClearToken ct; | |
818 | int i, type, len, plen; | |
819 | char buf[2048], *p, *server_cell; | |
610cd5c6 | 820 | char buffer[8192]; |
5260325f | 821 | |
822 | /* Move over ktc_GetToken, here's something leaner. */ | |
823 | for (i = 0; i < 100; i++) { /* just in case */ | |
824 | parms.in = (char *) &i; | |
825 | parms.in_size = sizeof(i); | |
826 | parms.out = buf; | |
827 | parms.out_size = sizeof(buf); | |
828 | if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0) | |
829 | break; | |
830 | p = buf; | |
831 | ||
832 | /* Get secret token. */ | |
833 | memcpy(&creds.ticket_st.length, p, sizeof(unsigned int)); | |
834 | if (creds.ticket_st.length > MAX_KTXT_LEN) | |
835 | break; | |
836 | p += sizeof(unsigned int); | |
837 | memcpy(creds.ticket_st.dat, p, creds.ticket_st.length); | |
838 | p += creds.ticket_st.length; | |
839 | ||
840 | /* Get clear token. */ | |
841 | memcpy(&len, p, sizeof(len)); | |
842 | if (len != sizeof(struct ClearToken)) | |
843 | break; | |
844 | p += sizeof(len); | |
845 | memcpy(&ct, p, len); | |
846 | p += len; | |
847 | p += sizeof(len); /* primary flag */ | |
848 | server_cell = p; | |
849 | ||
850 | /* Flesh out our credentials. */ | |
851 | strlcpy(creds.service, "afs", sizeof creds.service); | |
852 | creds.instance[0] = '\0'; | |
853 | strlcpy(creds.realm, server_cell, REALM_SZ); | |
854 | memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ); | |
855 | creds.issue_date = ct.BeginTimestamp; | |
856 | creds.lifetime = krb_time_to_life(creds.issue_date, ct.EndTimestamp); | |
857 | creds.kvno = ct.AuthHandle; | |
858 | snprintf(creds.pname, sizeof(creds.pname), "AFS ID %d", ct.ViceId); | |
859 | creds.pinst[0] = '\0'; | |
860 | ||
861 | /* Encode token, ship it off. */ | |
610cd5c6 | 862 | if (!creds_to_radix(&creds, (unsigned char*) buffer)) |
5260325f | 863 | break; |
864 | packet_start(SSH_CMSG_HAVE_AFS_TOKEN); | |
610cd5c6 | 865 | packet_put_string(buffer, strlen(buffer)); |
5260325f | 866 | packet_send(); |
867 | packet_write_wait(); | |
868 | ||
869 | /* Roger, Roger. Clearance, Clarence. What's your vector, | |
870 | Victor? */ | |
871 | type = packet_read(&plen); | |
872 | ||
873 | if (type == SSH_SMSG_FAILURE) | |
874 | debug("AFS token for cell %s rejected.", server_cell); | |
875 | else if (type != SSH_SMSG_SUCCESS) | |
876 | packet_disconnect("Protocol error on AFS token response: %d", type); | |
877 | } | |
8efc0c15 | 878 | } |
8efc0c15 | 879 | |
5260325f | 880 | #endif /* AFS */ |
8efc0c15 | 881 | |
57112b5a | 882 | /* |
883 | * Tries to authenticate with any string-based challenge/response system. | |
884 | * Note that the client code is not tied to s/key or TIS. | |
885 | */ | |
886 | int | |
887 | try_skey_authentication() | |
888 | { | |
610cd5c6 | 889 | int type, i; |
890 | int payload_len; | |
891 | unsigned int clen; | |
57112b5a | 892 | char *challenge, *response; |
893 | ||
894 | debug("Doing skey authentication."); | |
895 | ||
896 | /* request a challenge */ | |
897 | packet_start(SSH_CMSG_AUTH_TIS); | |
898 | packet_send(); | |
899 | packet_write_wait(); | |
900 | ||
901 | type = packet_read(&payload_len); | |
902 | if (type != SSH_SMSG_FAILURE && | |
903 | type != SSH_SMSG_AUTH_TIS_CHALLENGE) { | |
904 | packet_disconnect("Protocol error: got %d in response " | |
905 | "to skey-auth", type); | |
906 | } | |
907 | if (type != SSH_SMSG_AUTH_TIS_CHALLENGE) { | |
908 | debug("No challenge for skey authentication."); | |
909 | return 0; | |
910 | } | |
610cd5c6 | 911 | challenge = packet_get_string(&clen); |
912 | packet_integrity_check(payload_len, (4 + clen), type); | |
57112b5a | 913 | if (options.cipher == SSH_CIPHER_NONE) |
914 | log("WARNING: Encryption is disabled! " | |
915 | "Reponse will be transmitted in clear text."); | |
916 | fprintf(stderr, "%s\n", challenge); | |
c8d54615 | 917 | xfree(challenge); |
57112b5a | 918 | fflush(stderr); |
919 | for (i = 0; i < options.number_of_password_prompts; i++) { | |
920 | if (i != 0) | |
921 | error("Permission denied, please try again."); | |
922 | response = read_passphrase("Response: ", 0); | |
923 | packet_start(SSH_CMSG_AUTH_TIS_RESPONSE); | |
924 | packet_put_string(response, strlen(response)); | |
925 | memset(response, 0, strlen(response)); | |
926 | xfree(response); | |
927 | packet_send(); | |
928 | packet_write_wait(); | |
929 | type = packet_read(&payload_len); | |
930 | if (type == SSH_SMSG_SUCCESS) | |
931 | return 1; | |
932 | if (type != SSH_SMSG_FAILURE) | |
933 | packet_disconnect("Protocol error: got %d in response " | |
934 | "to skey-auth-reponse", type); | |
935 | } | |
936 | /* failure */ | |
937 | return 0; | |
938 | } | |
939 | ||
940 | /* | |
941 | * Tries to authenticate with plain passwd authentication. | |
942 | */ | |
943 | int | |
944 | try_password_authentication(char *prompt) | |
945 | { | |
946 | int type, i, payload_len; | |
947 | char *password; | |
948 | ||
949 | debug("Doing password authentication."); | |
950 | if (options.cipher == SSH_CIPHER_NONE) | |
951 | log("WARNING: Encryption is disabled! Password will be transmitted in clear text."); | |
952 | for (i = 0; i < options.number_of_password_prompts; i++) { | |
953 | if (i != 0) | |
954 | error("Permission denied, please try again."); | |
955 | password = read_passphrase(prompt, 0); | |
956 | packet_start(SSH_CMSG_AUTH_PASSWORD); | |
957 | packet_put_string(password, strlen(password)); | |
958 | memset(password, 0, strlen(password)); | |
959 | xfree(password); | |
960 | packet_send(); | |
961 | packet_write_wait(); | |
962 | ||
963 | type = packet_read(&payload_len); | |
964 | if (type == SSH_SMSG_SUCCESS) | |
965 | return 1; | |
966 | if (type != SSH_SMSG_FAILURE) | |
967 | packet_disconnect("Protocol error: got %d in response to passwd auth", type); | |
968 | } | |
969 | /* failure */ | |
970 | return 0; | |
971 | } | |
972 | ||
8ce64345 | 973 | char * |
974 | chop(char *s) | |
975 | { | |
976 | char *t = s; | |
977 | while (*t) { | |
978 | if(*t == '\n' || *t == '\r') { | |
979 | *t = '\0'; | |
980 | return s; | |
981 | } | |
982 | t++; | |
983 | } | |
984 | return s; | |
985 | ||
986 | } | |
987 | ||
5260325f | 988 | /* |
989 | * Waits for the server identification string, and sends our own | |
990 | * identification string. | |
991 | */ | |
992 | void | |
993 | ssh_exchange_identification() | |
8efc0c15 | 994 | { |
5260325f | 995 | char buf[256], remote_version[256]; /* must be same size! */ |
996 | int remote_major, remote_minor, i; | |
997 | int connection_in = packet_get_connection_in(); | |
998 | int connection_out = packet_get_connection_out(); | |
5260325f | 999 | |
1000 | /* Read other side\'s version identification. */ | |
1001 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
c8d54615 | 1002 | int len = read(connection_in, &buf[i], 1); |
1003 | if (len < 0) | |
5260325f | 1004 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); |
c8d54615 | 1005 | if (len != 1) |
1006 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
5260325f | 1007 | if (buf[i] == '\r') { |
1008 | buf[i] = '\n'; | |
1009 | buf[i + 1] = 0; | |
8ce64345 | 1010 | continue; /**XXX wait for \n */ |
5260325f | 1011 | } |
1012 | if (buf[i] == '\n') { | |
1013 | buf[i + 1] = 0; | |
1014 | break; | |
1015 | } | |
8efc0c15 | 1016 | } |
5260325f | 1017 | buf[sizeof(buf) - 1] = 0; |
8ce64345 | 1018 | server_version_string = xstrdup(buf); |
5260325f | 1019 | |
aa3378df | 1020 | /* |
1021 | * Check that the versions match. In future this might accept | |
1022 | * several versions and set appropriate flags to handle them. | |
1023 | */ | |
8ce64345 | 1024 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", |
1025 | &remote_major, &remote_minor, remote_version) != 3) | |
5260325f | 1026 | fatal("Bad remote protocol version identification: '%.100s'", buf); |
1027 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
1028 | remote_major, remote_minor, remote_version); | |
1029 | ||
8ce64345 | 1030 | /*** XXX option for disabling 2.0 or 1.5 */ |
1031 | compat_datafellows(remote_version); | |
1032 | ||
5260325f | 1033 | /* Check if the remote protocol version is too old. */ |
1034 | if (remote_major == 1 && remote_minor < 3) | |
1035 | fatal("Remote machine has too old SSH software version."); | |
1036 | ||
1037 | /* We speak 1.3, too. */ | |
1038 | if (remote_major == 1 && remote_minor == 3) { | |
1039 | enable_compat13(); | |
7b2ea3a1 | 1040 | if (options.forward_agent) { |
1041 | log("Agent forwarding disabled for protocol 1.3"); | |
5260325f | 1042 | options.forward_agent = 0; |
1043 | } | |
8efc0c15 | 1044 | } |
8ce64345 | 1045 | if ((remote_major == 2 && remote_minor == 0) || |
1046 | (remote_major == 1 && remote_minor == 99)) { | |
1047 | enable_compat20(); | |
1048 | } | |
8efc0c15 | 1049 | #if 0 |
aa3378df | 1050 | /* |
1051 | * Removed for now, to permit compatibility with latter versions. The | |
1052 | * server will reject our version and disconnect if it doesn't | |
1053 | * support it. | |
1054 | */ | |
5260325f | 1055 | if (remote_major != PROTOCOL_MAJOR) |
1056 | fatal("Protocol major versions differ: %d vs. %d", | |
1057 | PROTOCOL_MAJOR, remote_major); | |
8efc0c15 | 1058 | #endif |
5260325f | 1059 | /* Send our own protocol version identification. */ |
1060 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
8ce64345 | 1061 | compat20 ? 2 : PROTOCOL_MAJOR, |
1062 | compat20 ? 0 : PROTOCOL_MINOR, | |
1063 | SSH_VERSION); | |
a408af76 | 1064 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) |
5260325f | 1065 | fatal("write: %.100s", strerror(errno)); |
8ce64345 | 1066 | client_version_string = xstrdup(buf); |
1067 | chop(client_version_string); | |
1068 | chop(server_version_string); | |
1069 | debug("Local version string %.100s", client_version_string); | |
8efc0c15 | 1070 | } |
1071 | ||
5260325f | 1072 | int |
1073 | read_yes_or_no(const char *prompt, int defval) | |
8efc0c15 | 1074 | { |
5260325f | 1075 | char buf[1024]; |
1076 | FILE *f; | |
1077 | int retval = -1; | |
1078 | ||
1079 | if (isatty(0)) | |
1080 | f = stdin; | |
1081 | else | |
1082 | f = fopen("/dev/tty", "rw"); | |
1083 | ||
1084 | if (f == NULL) | |
1085 | return 0; | |
1086 | ||
1087 | fflush(stdout); | |
1088 | ||
1089 | while (1) { | |
1090 | fprintf(stderr, "%s", prompt); | |
1091 | if (fgets(buf, sizeof(buf), f) == NULL) { | |
1092 | /* Print a newline (the prompt probably didn\'t have one). */ | |
1093 | fprintf(stderr, "\n"); | |
1094 | strlcpy(buf, "no", sizeof buf); | |
1095 | } | |
1096 | /* Remove newline from response. */ | |
1097 | if (strchr(buf, '\n')) | |
1098 | *strchr(buf, '\n') = 0; | |
1099 | ||
1100 | if (buf[0] == 0) | |
1101 | retval = defval; | |
1102 | if (strcmp(buf, "yes") == 0) | |
1103 | retval = 1; | |
1104 | if (strcmp(buf, "no") == 0) | |
1105 | retval = 0; | |
1106 | ||
1107 | if (retval != -1) { | |
1108 | if (f != stdin) | |
1109 | fclose(f); | |
1110 | return retval; | |
1111 | } | |
8efc0c15 | 1112 | } |
8efc0c15 | 1113 | } |
1114 | ||
5260325f | 1115 | /* |
95f1eccc | 1116 | * check whether the supplied host key is valid, return only if ok. |
5260325f | 1117 | */ |
95f1eccc | 1118 | |
5260325f | 1119 | void |
4fe2af09 | 1120 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) |
8efc0c15 | 1121 | { |
4fe2af09 | 1122 | Key *file_key; |
95f1eccc | 1123 | char *ip = NULL; |
5260325f | 1124 | char hostline[1000], *hostp; |
5260325f | 1125 | HostStatus host_status; |
1126 | HostStatus ip_status; | |
48e671d5 | 1127 | int local = 0, host_ip_differ = 0; |
20af321f | 1128 | int salen; |
48e671d5 | 1129 | char ntop[NI_MAXHOST]; |
1130 | ||
1131 | /* | |
1132 | * Force accepting of the host key for loopback/localhost. The | |
1133 | * problem is that if the home directory is NFS-mounted to multiple | |
1134 | * machines, localhost will refer to a different machine in each of | |
1135 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
1136 | * essentially disables host authentication for localhost; however, | |
1137 | * this is probably not a real problem. | |
1138 | */ | |
1139 | switch (hostaddr->sa_family) { | |
1140 | case AF_INET: | |
1141 | local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; | |
20af321f | 1142 | salen = sizeof(struct sockaddr_in); |
48e671d5 | 1143 | break; |
1144 | case AF_INET6: | |
1145 | local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
20af321f | 1146 | salen = sizeof(struct sockaddr_in6); |
48e671d5 | 1147 | break; |
1148 | default: | |
1149 | local = 0; | |
20af321f | 1150 | salen = sizeof(struct sockaddr_storage); |
48e671d5 | 1151 | break; |
1152 | } | |
1153 | if (local) { | |
1154 | debug("Forcing accepting of host key for loopback/localhost."); | |
1155 | return; | |
1156 | } | |
5260325f | 1157 | |
57112b5a | 1158 | /* |
1159 | * Turn off check_host_ip for proxy connects, since | |
1160 | * we don't have the remote ip-address | |
1161 | */ | |
1162 | if (options.proxy_command != NULL && options.check_host_ip) | |
1163 | options.check_host_ip = 0; | |
1164 | ||
48e671d5 | 1165 | if (options.check_host_ip) { |
20af321f | 1166 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), |
48e671d5 | 1167 | NULL, 0, NI_NUMERICHOST) != 0) |
1168 | fatal("check_host_key: getnameinfo failed"); | |
1169 | ip = xstrdup(ntop); | |
1170 | } | |
5260325f | 1171 | |
95f1eccc | 1172 | /* |
1173 | * Store the host key from the known host file in here so that we can | |
1174 | * compare it with the key for the IP address. | |
1175 | */ | |
4fe2af09 | 1176 | file_key = key_new(host_key->type); |
5260325f | 1177 | |
aa3378df | 1178 | /* |
1179 | * Check if the host key is present in the user\'s list of known | |
1180 | * hosts or in the systemwide list. | |
1181 | */ | |
4fe2af09 | 1182 | host_status = check_host_in_hostfile(options.user_hostfile, host, host_key, file_key); |
5260325f | 1183 | if (host_status == HOST_NEW) |
4fe2af09 | 1184 | host_status = check_host_in_hostfile(options.system_hostfile, host, host_key, file_key); |
aa3378df | 1185 | /* |
1186 | * Also perform check for the ip address, skip the check if we are | |
1187 | * localhost or the hostname was an ip address to begin with | |
1188 | */ | |
5260325f | 1189 | if (options.check_host_ip && !local && strcmp(host, ip)) { |
4fe2af09 | 1190 | Key *ip_key = key_new(host_key->type); |
1191 | ip_status = check_host_in_hostfile(options.user_hostfile, ip, host_key, ip_key); | |
5260325f | 1192 | |
1193 | if (ip_status == HOST_NEW) | |
4fe2af09 | 1194 | ip_status = check_host_in_hostfile(options.system_hostfile, ip, host_key, ip_key); |
5260325f | 1195 | if (host_status == HOST_CHANGED && |
4fe2af09 | 1196 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) |
5260325f | 1197 | host_ip_differ = 1; |
1198 | ||
4fe2af09 | 1199 | key_free(ip_key); |
5260325f | 1200 | } else |
1201 | ip_status = host_status; | |
1202 | ||
4fe2af09 | 1203 | key_free(file_key); |
5260325f | 1204 | |
1205 | switch (host_status) { | |
1206 | case HOST_OK: | |
1207 | /* The host is known and the key matches. */ | |
1208 | debug("Host '%.200s' is known and matches the host key.", host); | |
1209 | if (options.check_host_ip) { | |
1210 | if (ip_status == HOST_NEW) { | |
4fe2af09 | 1211 | if (!add_host_to_hostfile(options.user_hostfile, ip, host_key)) |
5260325f | 1212 | log("Failed to add the host key for IP address '%.30s' to the list of known hosts (%.30s).", |
1213 | ip, options.user_hostfile); | |
1214 | else | |
1215 | log("Warning: Permanently added host key for IP address '%.30s' to the list of known hosts.", | |
1216 | ip); | |
1217 | } else if (ip_status != HOST_OK) | |
1218 | log("Warning: the host key for '%.200s' differs from the key for the IP address '%.30s'", | |
1219 | host, ip); | |
1220 | } | |
1221 | break; | |
1222 | case HOST_NEW: | |
1223 | /* The host is new. */ | |
1224 | if (options.strict_host_key_checking == 1) { | |
1225 | /* User has requested strict host key checking. We will not add the host key | |
1226 | automatically. The only alternative left is to abort. */ | |
1227 | fatal("No host key is known for %.200s and you have requested strict checking.", host); | |
1228 | } else if (options.strict_host_key_checking == 2) { | |
1229 | /* The default */ | |
1230 | char prompt[1024]; | |
4fe2af09 | 1231 | char *fp = key_fingerprint(host_key); |
5260325f | 1232 | snprintf(prompt, sizeof(prompt), |
a408af76 | 1233 | "The authenticity of host '%.200s' can't be established.\n" |
4fe2af09 | 1234 | "Key fingerprint is %s.\n" |
a408af76 | 1235 | "Are you sure you want to continue connecting (yes/no)? ", |
4fe2af09 | 1236 | host, fp); |
5260325f | 1237 | if (!read_yes_or_no(prompt, -1)) |
1238 | fatal("Aborted by user!\n"); | |
1239 | } | |
1240 | if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) { | |
1241 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); | |
1242 | hostp = hostline; | |
1243 | } else | |
1244 | hostp = host; | |
1245 | ||
1246 | /* If not in strict mode, add the key automatically to the local known_hosts file. */ | |
4fe2af09 | 1247 | if (!add_host_to_hostfile(options.user_hostfile, hostp, host_key)) |
5260325f | 1248 | log("Failed to add the host to the list of known hosts (%.500s).", |
1249 | options.user_hostfile); | |
1250 | else | |
1251 | log("Warning: Permanently added '%.200s' to the list of known hosts.", | |
1252 | hostp); | |
1253 | break; | |
1254 | case HOST_CHANGED: | |
1255 | if (options.check_host_ip && host_ip_differ) { | |
1256 | char *msg; | |
1257 | if (ip_status == HOST_NEW) | |
1258 | msg = "is unknown"; | |
1259 | else if (ip_status == HOST_OK) | |
1260 | msg = "is unchanged"; | |
1261 | else | |
1262 | msg = "has a different value"; | |
1263 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1264 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
1265 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1266 | error("The host key for %s has changed,", host); | |
1267 | error("and the key for the according IP address %s", ip); | |
1268 | error("%s. This could either mean that", msg); | |
1269 | error("DNS SPOOFING is happening or the IP address for the host"); | |
1270 | error("and its host key have changed at the same time"); | |
1271 | } | |
1272 | /* The host key has changed. */ | |
1273 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
ae2f7af7 | 1274 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); |
5260325f | 1275 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
1276 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
1277 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
1278 | error("It is also possible that the host key has just been changed."); | |
1279 | error("Please contact your system administrator."); | |
1280 | error("Add correct host key in %.100s to get rid of this message.", | |
1281 | options.user_hostfile); | |
1282 | ||
aa3378df | 1283 | /* |
1284 | * If strict host key checking is in use, the user will have | |
1285 | * to edit the key manually and we can only abort. | |
1286 | */ | |
5260325f | 1287 | if (options.strict_host_key_checking) |
1288 | fatal("Host key for %.200s has changed and you have requested strict checking.", host); | |
1289 | ||
aa3378df | 1290 | /* |
1291 | * If strict host key checking has not been requested, allow | |
1292 | * the connection but without password authentication or | |
1293 | * agent forwarding. | |
1294 | */ | |
5260325f | 1295 | if (options.password_authentication) { |
1296 | error("Password authentication is disabled to avoid trojan horses."); | |
1297 | options.password_authentication = 0; | |
1298 | } | |
1299 | if (options.forward_agent) { | |
1300 | error("Agent forwarding is disabled to avoid trojan horses."); | |
1301 | options.forward_agent = 0; | |
1302 | } | |
aa3378df | 1303 | /* |
1304 | * XXX Should permit the user to change to use the new id. | |
1305 | * This could be done by converting the host key to an | |
1306 | * identifying sentence, tell that the host identifies itself | |
1307 | * by that sentence, and ask the user if he/she whishes to | |
1308 | * accept the authentication. | |
1309 | */ | |
5260325f | 1310 | break; |
1311 | } | |
5260325f | 1312 | if (options.check_host_ip) |
1313 | xfree(ip); | |
95f1eccc | 1314 | } |
4fe2af09 | 1315 | void |
1316 | check_rsa_host_key(char *host, struct sockaddr *hostaddr, RSA *host_key) | |
1317 | { | |
1318 | Key k; | |
1319 | k.type = KEY_RSA; | |
1320 | k.rsa = host_key; | |
1321 | check_host_key(host, hostaddr, &k); | |
1322 | } | |
95f1eccc | 1323 | |
8ce64345 | 1324 | /* |
1325 | * SSH2 key exchange | |
1326 | */ | |
1327 | void | |
1328 | ssh_kex2(char *host, struct sockaddr *hostaddr) | |
1329 | { | |
1330 | Kex *kex; | |
1331 | char *cprop[PROPOSAL_MAX]; | |
1332 | char *sprop[PROPOSAL_MAX]; | |
1333 | Buffer *client_kexinit; | |
1334 | Buffer *server_kexinit; | |
1335 | int payload_len, dlen; | |
1336 | unsigned int klen, kout; | |
1337 | char *ptr; | |
1338 | char *signature = NULL; | |
1339 | unsigned int slen; | |
1340 | char *server_host_key_blob = NULL; | |
1341 | Key *server_host_key; | |
1342 | unsigned int sbloblen; | |
1343 | DH *dh; | |
1344 | BIGNUM *dh_server_pub = 0; | |
1345 | BIGNUM *shared_secret = 0; | |
1346 | int i; | |
1347 | unsigned char *kbuf; | |
1348 | unsigned char *hash; | |
1349 | ||
1350 | /* KEXINIT */ | |
1351 | ||
1352 | debug("Sending KEX init."); | |
1353 | if (options.cipher == SSH_CIPHER_ARCFOUR || | |
1354 | options.cipher == SSH_CIPHER_3DES_CBC || | |
1355 | options.cipher == SSH_CIPHER_CAST128_CBC || | |
1356 | options.cipher == SSH_CIPHER_BLOWFISH_CBC) { | |
1357 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = cipher_name(options.cipher); | |
1358 | myproposal[PROPOSAL_ENC_ALGS_STOC] = cipher_name(options.cipher); | |
1359 | } | |
1360 | if (options.compression) { | |
1361 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib"; | |
1362 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib"; | |
1363 | } else { | |
1364 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none"; | |
1365 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
1366 | } | |
1367 | for (i = 0; i < PROPOSAL_MAX; i++) | |
1368 | cprop[i] = xstrdup(myproposal[i]); | |
1369 | ||
1370 | client_kexinit = kex_init(cprop); | |
1371 | packet_start(SSH2_MSG_KEXINIT); | |
1372 | packet_put_raw(buffer_ptr(client_kexinit), buffer_len(client_kexinit)); | |
1373 | packet_send(); | |
1374 | packet_write_wait(); | |
1375 | ||
1376 | debug("done"); | |
1377 | ||
1378 | packet_read_expect(&payload_len, SSH2_MSG_KEXINIT); | |
1379 | ||
1380 | /* save payload for session_id */ | |
1381 | server_kexinit = xmalloc(sizeof(*server_kexinit)); | |
1382 | buffer_init(server_kexinit); | |
1383 | ptr = packet_get_raw(&payload_len); | |
1384 | buffer_append(server_kexinit, ptr, payload_len); | |
1385 | ||
1386 | /* skip cookie */ | |
1387 | for (i = 0; i < 16; i++) | |
1388 | (void) packet_get_char(); | |
1389 | /* kex init proposal strings */ | |
1390 | for (i = 0; i < PROPOSAL_MAX; i++) { | |
1391 | sprop[i] = packet_get_string(NULL); | |
1392 | debug("got kexinit string: %s", sprop[i]); | |
1393 | } | |
1394 | i = (int) packet_get_char(); | |
1395 | debug("first kex follow == %d", i); | |
1396 | i = packet_get_int(); | |
1397 | debug("reserved == %d", i); | |
1398 | ||
1399 | debug("done read kexinit"); | |
1400 | kex = kex_choose_conf(cprop, sprop, 0); | |
1401 | ||
1402 | /* KEXDH */ | |
1403 | ||
1404 | debug("Sending SSH2_MSG_KEXDH_INIT."); | |
1405 | ||
1406 | /* generate and send 'e', client DH public key */ | |
1407 | dh = new_dh_group1(); | |
1408 | packet_start(SSH2_MSG_KEXDH_INIT); | |
1409 | packet_put_bignum2(dh->pub_key); | |
1410 | packet_send(); | |
1411 | packet_write_wait(); | |
1412 | ||
1413 | #ifdef DEBUG_KEXDH | |
1414 | fprintf(stderr, "\np= "); | |
1415 | bignum_print(dh->p); | |
1416 | fprintf(stderr, "\ng= "); | |
1417 | bignum_print(dh->g); | |
1418 | fprintf(stderr, "\npub= "); | |
1419 | bignum_print(dh->pub_key); | |
1420 | fprintf(stderr, "\n"); | |
1421 | DHparams_print_fp(stderr, dh); | |
1422 | #endif | |
1423 | ||
1424 | debug("Wait SSH2_MSG_KEXDH_REPLY."); | |
1425 | ||
1426 | packet_read_expect(&payload_len, SSH2_MSG_KEXDH_REPLY); | |
1427 | ||
1428 | debug("Got SSH2_MSG_KEXDH_REPLY."); | |
1429 | ||
1430 | /* key, cert */ | |
1431 | server_host_key_blob = packet_get_string(&sbloblen); | |
1432 | server_host_key = dsa_serverkey_from_blob(server_host_key_blob, sbloblen); | |
1433 | if (server_host_key == NULL) | |
1434 | fatal("cannot decode server_host_key_blob"); | |
1435 | ||
1436 | check_host_key(host, hostaddr, server_host_key); | |
1437 | ||
1438 | /* DH paramter f, server public DH key */ | |
1439 | dh_server_pub = BN_new(); | |
1440 | if (dh_server_pub == NULL) | |
1441 | fatal("dh_server_pub == NULL"); | |
1442 | packet_get_bignum2(dh_server_pub, &dlen); | |
1443 | ||
1444 | #ifdef DEBUG_KEXDH | |
1445 | fprintf(stderr, "\ndh_server_pub= "); | |
1446 | bignum_print(dh_server_pub); | |
1447 | fprintf(stderr, "\n"); | |
1448 | debug("bits %d", BN_num_bits(dh_server_pub)); | |
1449 | #endif | |
1450 | ||
1451 | /* signed H */ | |
1452 | signature = packet_get_string(&slen); | |
1453 | ||
1454 | klen = DH_size(dh); | |
1455 | kbuf = xmalloc(klen); | |
1456 | kout = DH_compute_key(kbuf, dh_server_pub, dh); | |
1457 | #ifdef DEBUG_KEXDH | |
1458 | debug("shared secret: len %d/%d", klen, kout); | |
1459 | fprintf(stderr, "shared secret == "); | |
1460 | for (i = 0; i< kout; i++) | |
1461 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
1462 | fprintf(stderr, "\n"); | |
1463 | #endif | |
1464 | shared_secret = BN_new(); | |
1465 | ||
1466 | BN_bin2bn(kbuf, kout, shared_secret); | |
1467 | memset(kbuf, 0, klen); | |
1468 | xfree(kbuf); | |
1469 | ||
1470 | /* calc and verify H */ | |
1471 | hash = kex_hash( | |
1472 | client_version_string, | |
1473 | server_version_string, | |
1474 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
1475 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
1476 | server_host_key_blob, sbloblen, | |
1477 | dh->pub_key, | |
1478 | dh_server_pub, | |
1479 | shared_secret | |
1480 | ); | |
1481 | buffer_free(client_kexinit); | |
1482 | buffer_free(server_kexinit); | |
1483 | xfree(client_kexinit); | |
1484 | xfree(server_kexinit); | |
1485 | #ifdef DEBUG_KEXDH | |
1486 | fprintf(stderr, "hash == "); | |
1487 | for (i = 0; i< 20; i++) | |
1488 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
1489 | fprintf(stderr, "\n"); | |
1490 | #endif | |
1491 | dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20); | |
1492 | key_free(server_host_key); | |
1493 | ||
1494 | kex_derive_keys(kex, hash, shared_secret); | |
1495 | packet_set_kex(kex); | |
1496 | ||
1497 | /* have keys, free DH */ | |
1498 | DH_free(dh); | |
1499 | ||
1500 | debug("Wait SSH2_MSG_NEWKEYS."); | |
1501 | packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS); | |
1502 | debug("GOT SSH2_MSG_NEWKEYS."); | |
1503 | ||
1504 | debug("send SSH2_MSG_NEWKEYS."); | |
1505 | packet_start(SSH2_MSG_NEWKEYS); | |
1506 | packet_send(); | |
1507 | packet_write_wait(); | |
1508 | debug("done: send SSH2_MSG_NEWKEYS."); | |
1509 | ||
1510 | /* send 1st encrypted/maced/compressed message */ | |
1511 | packet_start(SSH2_MSG_IGNORE); | |
1512 | packet_put_cstring("markus"); | |
1513 | packet_send(); | |
1514 | packet_write_wait(); | |
1515 | ||
1516 | debug("done: KEX2."); | |
1517 | } | |
1518 | /* | |
1519 | * Authenticate user | |
1520 | */ | |
1521 | void | |
1522 | ssh_userauth2(int host_key_valid, RSA *own_host_key, | |
1523 | uid_t original_real_uid, char *host) | |
1524 | { | |
1525 | int type; | |
1526 | int plen; | |
1527 | unsigned int dlen; | |
1528 | int partial; | |
1529 | struct passwd *pw; | |
1530 | char *server_user, *local_user; | |
1531 | char *auths; | |
1532 | char *password; | |
1533 | char *service = "ssh-connection"; // service name | |
1534 | ||
1535 | debug("send SSH2_MSG_SERVICE_REQUEST"); | |
1536 | packet_start(SSH2_MSG_SERVICE_REQUEST); | |
1537 | packet_put_cstring("ssh-userauth"); | |
1538 | packet_send(); | |
1539 | packet_write_wait(); | |
1540 | ||
1541 | type = packet_read(&plen); | |
1542 | if (type != SSH2_MSG_SERVICE_ACCEPT) { | |
1543 | fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type); | |
1544 | } | |
1545 | /* payload empty for ssh-2.0.13 ?? */ | |
1546 | /* reply = packet_get_string(&payload_len); */ | |
1547 | debug("got SSH2_MSG_SERVICE_ACCEPT"); | |
1548 | ||
1549 | /*XX COMMONCODE: */ | |
1550 | /* Get local user name. Use it as server user if no user name was given. */ | |
1551 | pw = getpwuid(original_real_uid); | |
1552 | if (!pw) | |
1553 | fatal("User id %d not found from user database.", original_real_uid); | |
1554 | local_user = xstrdup(pw->pw_name); | |
1555 | server_user = options.user ? options.user : local_user; | |
1556 | ||
1557 | /* INITIAL request for auth */ | |
1558 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
1559 | packet_put_cstring(server_user); | |
1560 | packet_put_cstring(service); | |
1561 | packet_put_cstring("none"); | |
1562 | packet_send(); | |
1563 | packet_write_wait(); | |
1564 | ||
1565 | for (;;) { | |
1566 | type = packet_read(&plen); | |
1567 | if (type == SSH2_MSG_USERAUTH_SUCCESS) | |
1568 | break; | |
1569 | if (type != SSH2_MSG_USERAUTH_FAILURE) | |
1570 | fatal("access denied: %d", type); | |
1571 | /* SSH2_MSG_USERAUTH_FAILURE means: try again */ | |
1572 | auths = packet_get_string(&dlen); | |
1573 | debug("authentications that can continue: %s", auths); | |
1574 | partial = packet_get_char(); | |
1575 | if (partial) | |
1576 | debug("partial success"); | |
1577 | if (strstr(auths, "password") == NULL) | |
1578 | fatal("passwd auth not supported: %s", auths); | |
1579 | xfree(auths); | |
1580 | /* try passwd */ | |
1581 | password = read_passphrase("password: ", 0); | |
1582 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
1583 | packet_put_cstring(server_user); | |
1584 | packet_put_cstring(service); | |
1585 | packet_put_cstring("password"); | |
1586 | packet_put_char(0); | |
1587 | packet_put_cstring(password); | |
1588 | memset(password, 0, strlen(password)); | |
1589 | xfree(password); | |
1590 | packet_send(); | |
1591 | packet_write_wait(); | |
1592 | } | |
1593 | debug("ssh-userauth2 successfull"); | |
1594 | } | |
1595 | ||
95f1eccc | 1596 | /* |
7b2ea3a1 | 1597 | * SSH1 key exchange |
95f1eccc | 1598 | */ |
1599 | void | |
7b2ea3a1 | 1600 | ssh_kex(char *host, struct sockaddr *hostaddr) |
95f1eccc | 1601 | { |
7b2ea3a1 | 1602 | int i; |
95f1eccc | 1603 | BIGNUM *key; |
1604 | RSA *host_key; | |
1605 | RSA *public_key; | |
1606 | int bits, rbits; | |
8ce64345 | 1607 | int ssh_cipher_default = SSH_CIPHER_3DES; |
95f1eccc | 1608 | unsigned char session_key[SSH_SESSION_KEY_LENGTH]; |
7b2ea3a1 | 1609 | unsigned char cookie[8]; |
1610 | unsigned int supported_ciphers; | |
95f1eccc | 1611 | unsigned int server_flags, client_flags; |
1612 | int payload_len, clen, sum_len = 0; | |
1613 | u_int32_t rand = 0; | |
1614 | ||
95f1eccc | 1615 | debug("Waiting for server public key."); |
1616 | ||
1617 | /* Wait for a public key packet from the server. */ | |
1618 | packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY); | |
1619 | ||
7b2ea3a1 | 1620 | /* Get cookie from the packet. */ |
95f1eccc | 1621 | for (i = 0; i < 8; i++) |
7b2ea3a1 | 1622 | cookie[i] = packet_get_char(); |
95f1eccc | 1623 | |
1624 | /* Get the public key. */ | |
1625 | public_key = RSA_new(); | |
1626 | bits = packet_get_int();/* bits */ | |
1627 | public_key->e = BN_new(); | |
1628 | packet_get_bignum(public_key->e, &clen); | |
1629 | sum_len += clen; | |
1630 | public_key->n = BN_new(); | |
1631 | packet_get_bignum(public_key->n, &clen); | |
1632 | sum_len += clen; | |
1633 | ||
1634 | rbits = BN_num_bits(public_key->n); | |
1635 | if (bits != rbits) { | |
1636 | log("Warning: Server lies about size of server public key: " | |
1637 | "actual size is %d bits vs. announced %d.", rbits, bits); | |
1638 | log("Warning: This may be due to an old implementation of ssh."); | |
1639 | } | |
1640 | /* Get the host key. */ | |
1641 | host_key = RSA_new(); | |
1642 | bits = packet_get_int();/* bits */ | |
1643 | host_key->e = BN_new(); | |
1644 | packet_get_bignum(host_key->e, &clen); | |
1645 | sum_len += clen; | |
1646 | host_key->n = BN_new(); | |
1647 | packet_get_bignum(host_key->n, &clen); | |
1648 | sum_len += clen; | |
1649 | ||
1650 | rbits = BN_num_bits(host_key->n); | |
1651 | if (bits != rbits) { | |
1652 | log("Warning: Server lies about size of server host key: " | |
1653 | "actual size is %d bits vs. announced %d.", rbits, bits); | |
1654 | log("Warning: This may be due to an old implementation of ssh."); | |
1655 | } | |
1656 | ||
1657 | /* Get protocol flags. */ | |
1658 | server_flags = packet_get_int(); | |
1659 | packet_set_protocol_flags(server_flags); | |
1660 | ||
1661 | supported_ciphers = packet_get_int(); | |
1662 | supported_authentications = packet_get_int(); | |
1663 | ||
1664 | debug("Received server public key (%d bits) and host key (%d bits).", | |
1665 | BN_num_bits(public_key->n), BN_num_bits(host_key->n)); | |
1666 | ||
1667 | packet_integrity_check(payload_len, | |
1668 | 8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4, | |
1669 | SSH_SMSG_PUBLIC_KEY); | |
1670 | ||
4fe2af09 | 1671 | check_rsa_host_key(host, hostaddr, host_key); |
95f1eccc | 1672 | |
1673 | client_flags = SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN; | |
1674 | ||
7b2ea3a1 | 1675 | compute_session_id(session_id, cookie, host_key->n, public_key->n); |
5260325f | 1676 | |
1677 | /* Generate a session key. */ | |
1678 | arc4random_stir(); | |
1679 | ||
aa3378df | 1680 | /* |
1681 | * Generate an encryption key for the session. The key is a 256 bit | |
1682 | * random number, interpreted as a 32-byte key, with the least | |
1683 | * significant 8 bits being the first byte of the key. | |
1684 | */ | |
5260325f | 1685 | for (i = 0; i < 32; i++) { |
1686 | if (i % 4 == 0) | |
1687 | rand = arc4random(); | |
1688 | session_key[i] = rand & 0xff; | |
1689 | rand >>= 8; | |
1690 | } | |
1691 | ||
aa3378df | 1692 | /* |
1693 | * According to the protocol spec, the first byte of the session key | |
1694 | * is the highest byte of the integer. The session key is xored with | |
1695 | * the first 16 bytes of the session id. | |
1696 | */ | |
5260325f | 1697 | key = BN_new(); |
1698 | BN_set_word(key, 0); | |
1699 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
1700 | BN_lshift(key, key, 8); | |
1701 | if (i < 16) | |
1702 | BN_add_word(key, session_key[i] ^ session_id[i]); | |
1703 | else | |
1704 | BN_add_word(key, session_key[i]); | |
1705 | } | |
1706 | ||
aa3378df | 1707 | /* |
1708 | * Encrypt the integer using the public key and host key of the | |
1709 | * server (key with smaller modulus first). | |
1710 | */ | |
5260325f | 1711 | if (BN_cmp(public_key->n, host_key->n) < 0) { |
1712 | /* Public key has smaller modulus. */ | |
1713 | if (BN_num_bits(host_key->n) < | |
1714 | BN_num_bits(public_key->n) + SSH_KEY_BITS_RESERVED) { | |
1715 | fatal("respond_to_rsa_challenge: host_key %d < public_key %d + " | |
1716 | "SSH_KEY_BITS_RESERVED %d", | |
1717 | BN_num_bits(host_key->n), | |
1718 | BN_num_bits(public_key->n), | |
1719 | SSH_KEY_BITS_RESERVED); | |
1720 | } | |
1721 | rsa_public_encrypt(key, key, public_key); | |
1722 | rsa_public_encrypt(key, key, host_key); | |
1723 | } else { | |
1724 | /* Host key has smaller modulus (or they are equal). */ | |
1725 | if (BN_num_bits(public_key->n) < | |
1726 | BN_num_bits(host_key->n) + SSH_KEY_BITS_RESERVED) { | |
1727 | fatal("respond_to_rsa_challenge: public_key %d < host_key %d + " | |
1728 | "SSH_KEY_BITS_RESERVED %d", | |
1729 | BN_num_bits(public_key->n), | |
1730 | BN_num_bits(host_key->n), | |
1731 | SSH_KEY_BITS_RESERVED); | |
1732 | } | |
1733 | rsa_public_encrypt(key, key, host_key); | |
1734 | rsa_public_encrypt(key, key, public_key); | |
1735 | } | |
1736 | ||
7b2ea3a1 | 1737 | /* Destroy the public keys since we no longer need them. */ |
1738 | RSA_free(public_key); | |
1739 | RSA_free(host_key); | |
1740 | ||
5260325f | 1741 | if (options.cipher == SSH_CIPHER_NOT_SET) { |
8ce64345 | 1742 | if (cipher_mask1() & supported_ciphers & (1 << ssh_cipher_default)) |
5260325f | 1743 | options.cipher = ssh_cipher_default; |
1744 | else { | |
1745 | debug("Cipher %s not supported, using %.100s instead.", | |
1746 | cipher_name(ssh_cipher_default), | |
1747 | cipher_name(SSH_FALLBACK_CIPHER)); | |
1748 | options.cipher = SSH_FALLBACK_CIPHER; | |
1749 | } | |
1750 | } | |
1751 | /* Check that the selected cipher is supported. */ | |
1752 | if (!(supported_ciphers & (1 << options.cipher))) | |
1753 | fatal("Selected cipher type %.100s not supported by server.", | |
1754 | cipher_name(options.cipher)); | |
1755 | ||
1756 | debug("Encryption type: %.100s", cipher_name(options.cipher)); | |
1757 | ||
1758 | /* Send the encrypted session key to the server. */ | |
1759 | packet_start(SSH_CMSG_SESSION_KEY); | |
1760 | packet_put_char(options.cipher); | |
1761 | ||
7b2ea3a1 | 1762 | /* Send the cookie back to the server. */ |
5260325f | 1763 | for (i = 0; i < 8; i++) |
7b2ea3a1 | 1764 | packet_put_char(cookie[i]); |
5260325f | 1765 | |
7b2ea3a1 | 1766 | /* Send and destroy the encrypted encryption key integer. */ |
5260325f | 1767 | packet_put_bignum(key); |
7b2ea3a1 | 1768 | BN_clear_free(key); |
5260325f | 1769 | |
1770 | /* Send protocol flags. */ | |
95f1eccc | 1771 | packet_put_int(client_flags); |
5260325f | 1772 | |
1773 | /* Send the packet now. */ | |
8efc0c15 | 1774 | packet_send(); |
1775 | packet_write_wait(); | |
5260325f | 1776 | |
5260325f | 1777 | debug("Sent encrypted session key."); |
1778 | ||
1779 | /* Set the encryption key. */ | |
1780 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, options.cipher); | |
1781 | ||
1782 | /* We will no longer need the session key here. Destroy any extra copies. */ | |
1783 | memset(session_key, 0, sizeof(session_key)); | |
1784 | ||
aa3378df | 1785 | /* |
1786 | * Expect a success message from the server. Note that this message | |
1787 | * will be received in encrypted form. | |
1788 | */ | |
5260325f | 1789 | packet_read_expect(&payload_len, SSH_SMSG_SUCCESS); |
1790 | ||
1791 | debug("Received encrypted confirmation."); | |
7b2ea3a1 | 1792 | } |
1793 | ||
1794 | /* | |
1795 | * Authenticate user | |
1796 | */ | |
1797 | void | |
1798 | ssh_userauth(int host_key_valid, RSA *own_host_key, | |
1799 | uid_t original_real_uid, char *host) | |
1800 | { | |
1801 | int i, type; | |
1802 | int payload_len; | |
1803 | struct passwd *pw; | |
1804 | const char *server_user, *local_user; | |
1805 | ||
1806 | /* Get local user name. Use it as server user if no user name was given. */ | |
1807 | pw = getpwuid(original_real_uid); | |
1808 | if (!pw) | |
1809 | fatal("User id %d not found from user database.", original_real_uid); | |
1810 | local_user = xstrdup(pw->pw_name); | |
1811 | server_user = options.user ? options.user : local_user; | |
5260325f | 1812 | |
1813 | /* Send the name of the user to log in as on the server. */ | |
1814 | packet_start(SSH_CMSG_USER); | |
1815 | packet_put_string(server_user, strlen(server_user)); | |
1816 | packet_send(); | |
1817 | packet_write_wait(); | |
1818 | ||
aa3378df | 1819 | /* |
1820 | * The server should respond with success if no authentication is | |
1821 | * needed (the user has no password). Otherwise the server responds | |
1822 | * with failure. | |
1823 | */ | |
8efc0c15 | 1824 | type = packet_read(&payload_len); |
5260325f | 1825 | |
1826 | /* check whether the connection was accepted without authentication. */ | |
8efc0c15 | 1827 | if (type == SSH_SMSG_SUCCESS) |
5260325f | 1828 | return; |
8efc0c15 | 1829 | if (type != SSH_SMSG_FAILURE) |
5260325f | 1830 | packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER", |
1831 | type); | |
1832 | ||
1833 | #ifdef AFS | |
1834 | /* Try Kerberos tgt passing if the server supports it. */ | |
1835 | if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) && | |
1836 | options.kerberos_tgt_passing) { | |
1837 | if (options.cipher == SSH_CIPHER_NONE) | |
1838 | log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!"); | |
1839 | (void) send_kerberos_tgt(); | |
1840 | } | |
1841 | /* Try AFS token passing if the server supports it. */ | |
1842 | if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) && | |
1843 | options.afs_token_passing && k_hasafs()) { | |
1844 | if (options.cipher == SSH_CIPHER_NONE) | |
1845 | log("WARNING: Encryption is disabled! Token will be transmitted in the clear!"); | |
1846 | send_afs_tokens(); | |
1847 | } | |
1848 | #endif /* AFS */ | |
8efc0c15 | 1849 | |
5260325f | 1850 | #ifdef KRB4 |
1851 | if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) && | |
1852 | options.kerberos_authentication) { | |
1853 | debug("Trying Kerberos authentication."); | |
1854 | if (try_kerberos_authentication()) { | |
1855 | /* The server should respond with success or failure. */ | |
1856 | type = packet_read(&payload_len); | |
1857 | if (type == SSH_SMSG_SUCCESS) | |
1858 | return; | |
1859 | if (type != SSH_SMSG_FAILURE) | |
1860 | packet_disconnect("Protocol error: got %d in response to Kerberos auth", type); | |
1861 | } | |
1862 | } | |
1863 | #endif /* KRB4 */ | |
1864 | ||
aa3378df | 1865 | /* |
1866 | * Use rhosts authentication if running in privileged socket and we | |
1867 | * do not wish to remain anonymous. | |
1868 | */ | |
5260325f | 1869 | if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) && |
1870 | options.rhosts_authentication) { | |
1871 | debug("Trying rhosts authentication."); | |
1872 | packet_start(SSH_CMSG_AUTH_RHOSTS); | |
1873 | packet_put_string(local_user, strlen(local_user)); | |
1874 | packet_send(); | |
1875 | packet_write_wait(); | |
1876 | ||
1877 | /* The server should respond with success or failure. */ | |
1878 | type = packet_read(&payload_len); | |
1879 | if (type == SSH_SMSG_SUCCESS) | |
1880 | return; | |
1881 | if (type != SSH_SMSG_FAILURE) | |
1882 | packet_disconnect("Protocol error: got %d in response to rhosts auth", | |
1883 | type); | |
1884 | } | |
aa3378df | 1885 | /* |
1886 | * Try .rhosts or /etc/hosts.equiv authentication with RSA host | |
1887 | * authentication. | |
1888 | */ | |
5260325f | 1889 | if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) && |
1890 | options.rhosts_rsa_authentication && host_key_valid) { | |
1891 | if (try_rhosts_rsa_authentication(local_user, own_host_key)) | |
1892 | return; | |
1893 | } | |
1894 | /* Try RSA authentication if the server supports it. */ | |
1895 | if ((supported_authentications & (1 << SSH_AUTH_RSA)) && | |
1896 | options.rsa_authentication) { | |
aa3378df | 1897 | /* |
1898 | * Try RSA authentication using the authentication agent. The | |
1899 | * agent is tried first because no passphrase is needed for | |
1900 | * it, whereas identity files may require passphrases. | |
1901 | */ | |
5260325f | 1902 | if (try_agent_authentication()) |
1903 | return; | |
1904 | ||
1905 | /* Try RSA authentication for each identity. */ | |
1906 | for (i = 0; i < options.num_identity_files; i++) | |
57112b5a | 1907 | if (try_rsa_authentication(options.identity_files[i])) |
5260325f | 1908 | return; |
1909 | } | |
1910 | /* Try skey authentication if the server supports it. */ | |
1911 | if ((supported_authentications & (1 << SSH_AUTH_TIS)) && | |
1912 | options.skey_authentication && !options.batch_mode) { | |
57112b5a | 1913 | if (try_skey_authentication()) |
1914 | return; | |
5260325f | 1915 | } |
1916 | /* Try password authentication if the server supports it. */ | |
1917 | if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) && | |
1918 | options.password_authentication && !options.batch_mode) { | |
1919 | char prompt[80]; | |
a408af76 | 1920 | |
57112b5a | 1921 | snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ", |
a408af76 | 1922 | server_user, host); |
57112b5a | 1923 | if (try_password_authentication(prompt)) |
1924 | return; | |
5260325f | 1925 | } |
1926 | /* All authentication methods have failed. Exit with an error message. */ | |
1927 | fatal("Permission denied."); | |
1928 | /* NOTREACHED */ | |
8efc0c15 | 1929 | } |
7b2ea3a1 | 1930 | /* |
1931 | * Starts a dialog with the server, and authenticates the current user on the | |
1932 | * server. This does not need any extra privileges. The basic connection | |
1933 | * to the server must already have been established before this is called. | |
1934 | * If login fails, this function prints an error and never returns. | |
1935 | * This function does not require super-user privileges. | |
1936 | */ | |
1937 | void | |
1938 | ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost, | |
1939 | struct sockaddr *hostaddr, uid_t original_real_uid) | |
1940 | { | |
1941 | char *host, *cp; | |
1942 | ||
1943 | /* Convert the user-supplied hostname into all lowercase. */ | |
1944 | host = xstrdup(orighost); | |
1945 | for (cp = host; *cp; cp++) | |
1946 | if (isupper(*cp)) | |
1947 | *cp = tolower(*cp); | |
1948 | ||
1949 | /* Exchange protocol version identification strings with the server. */ | |
1950 | ssh_exchange_identification(); | |
1951 | ||
1952 | /* Put the connection into non-blocking mode. */ | |
1953 | packet_set_nonblocking(); | |
1954 | ||
7b2ea3a1 | 1955 | /* key exchange */ |
7b2ea3a1 | 1956 | /* authenticate user */ |
8ce64345 | 1957 | if (compat20) { |
1958 | ssh_kex2(host, hostaddr); | |
1959 | ssh_userauth2(host_key_valid, own_host_key, original_real_uid, host); | |
1960 | } else { | |
1961 | supported_authentications = 0; | |
1962 | ssh_kex(host, hostaddr); | |
1963 | if (supported_authentications == 0) | |
1964 | fatal("supported_authentications == 0."); | |
1965 | ssh_userauth(host_key_valid, own_host_key, original_real_uid, host); | |
1966 | } | |
7b2ea3a1 | 1967 | } |