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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" | |
9da5c3c9 | 13 | RCSID("$OpenBSD: sshconnect.c,v 1.69 2000/04/19 07:05:50 deraadt Exp $"); |
8efc0c15 | 14 | |
8ce64345 | 15 | #include <openssl/bn.h> |
8efc0c15 | 16 | #include "xmalloc.h" |
17 | #include "rsa.h" | |
18 | #include "ssh.h" | |
8ce64345 | 19 | #include "buffer.h" |
8efc0c15 | 20 | #include "packet.h" |
21 | #include "authfd.h" | |
22 | #include "cipher.h" | |
23 | #include "mpaux.h" | |
24 | #include "uidswap.h" | |
25 | #include "compat.h" | |
6fa724bc | 26 | #include "readconf.h" |
8ce64345 | 27 | |
28 | #include "bufaux.h" | |
35484284 | 29 | #include <openssl/rsa.h> |
30 | #include <openssl/dsa.h> | |
8ce64345 | 31 | |
32 | #include "ssh2.h" | |
35484284 | 33 | #include <openssl/md5.h> |
34 | #include <openssl/dh.h> | |
35 | #include <openssl/hmac.h> | |
8ce64345 | 36 | #include "kex.h" |
37 | #include "myproposal.h" | |
4fe2af09 | 38 | #include "key.h" |
8ce64345 | 39 | #include "dsa.h" |
4fe2af09 | 40 | #include "hostfile.h" |
8efc0c15 | 41 | |
42 | /* Session id for the current session. */ | |
43 | unsigned char session_id[16]; | |
44 | ||
7b2ea3a1 | 45 | /* authentications supported by server */ |
46 | unsigned int supported_authentications; | |
47 | ||
8ce64345 | 48 | static char *client_version_string = NULL; |
49 | static char *server_version_string = NULL; | |
50 | ||
57112b5a | 51 | extern Options options; |
48e671d5 | 52 | extern char *__progname; |
57112b5a | 53 | |
5260325f | 54 | /* |
55 | * Connect to the given ssh server using a proxy command. | |
56 | */ | |
8efc0c15 | 57 | int |
57112b5a | 58 | ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid, |
8efc0c15 | 59 | const char *proxy_command) |
60 | { | |
5260325f | 61 | Buffer command; |
62 | const char *cp; | |
63 | char *command_string; | |
64 | int pin[2], pout[2]; | |
9da5c3c9 | 65 | pid_t pid; |
48e671d5 | 66 | char strport[NI_MAXSERV]; |
5260325f | 67 | |
68 | /* Convert the port number into a string. */ | |
48e671d5 | 69 | snprintf(strport, sizeof strport, "%hu", port); |
5260325f | 70 | |
71 | /* Build the final command string in the buffer by making the | |
72 | appropriate substitutions to the given proxy command. */ | |
73 | buffer_init(&command); | |
74 | for (cp = proxy_command; *cp; cp++) { | |
75 | if (cp[0] == '%' && cp[1] == '%') { | |
76 | buffer_append(&command, "%", 1); | |
77 | cp++; | |
78 | continue; | |
79 | } | |
80 | if (cp[0] == '%' && cp[1] == 'h') { | |
81 | buffer_append(&command, host, strlen(host)); | |
82 | cp++; | |
83 | continue; | |
84 | } | |
85 | if (cp[0] == '%' && cp[1] == 'p') { | |
48e671d5 | 86 | buffer_append(&command, strport, strlen(strport)); |
5260325f | 87 | cp++; |
88 | continue; | |
89 | } | |
90 | buffer_append(&command, cp, 1); | |
8efc0c15 | 91 | } |
5260325f | 92 | buffer_append(&command, "\0", 1); |
93 | ||
94 | /* Get the final command string. */ | |
95 | command_string = buffer_ptr(&command); | |
96 | ||
97 | /* Create pipes for communicating with the proxy. */ | |
98 | if (pipe(pin) < 0 || pipe(pout) < 0) | |
99 | fatal("Could not create pipes to communicate with the proxy: %.100s", | |
100 | strerror(errno)); | |
101 | ||
102 | debug("Executing proxy command: %.500s", command_string); | |
103 | ||
104 | /* Fork and execute the proxy command. */ | |
105 | if ((pid = fork()) == 0) { | |
106 | char *argv[10]; | |
107 | ||
108 | /* Child. Permanently give up superuser privileges. */ | |
109 | permanently_set_uid(original_real_uid); | |
110 | ||
111 | /* Redirect stdin and stdout. */ | |
112 | close(pin[1]); | |
113 | if (pin[0] != 0) { | |
114 | if (dup2(pin[0], 0) < 0) | |
115 | perror("dup2 stdin"); | |
116 | close(pin[0]); | |
117 | } | |
118 | close(pout[0]); | |
119 | if (dup2(pout[1], 1) < 0) | |
120 | perror("dup2 stdout"); | |
121 | /* Cannot be 1 because pin allocated two descriptors. */ | |
122 | close(pout[1]); | |
123 | ||
124 | /* Stderr is left as it is so that error messages get | |
125 | printed on the user's terminal. */ | |
126 | argv[0] = "/bin/sh"; | |
127 | argv[1] = "-c"; | |
128 | argv[2] = command_string; | |
129 | argv[3] = NULL; | |
130 | ||
131 | /* Execute the proxy command. Note that we gave up any | |
132 | extra privileges above. */ | |
133 | execv("/bin/sh", argv); | |
134 | perror("/bin/sh"); | |
135 | exit(1); | |
8efc0c15 | 136 | } |
5260325f | 137 | /* Parent. */ |
138 | if (pid < 0) | |
139 | fatal("fork failed: %.100s", strerror(errno)); | |
140 | ||
141 | /* Close child side of the descriptors. */ | |
142 | close(pin[0]); | |
143 | close(pout[1]); | |
144 | ||
145 | /* Free the command name. */ | |
146 | buffer_free(&command); | |
147 | ||
148 | /* Set the connection file descriptors. */ | |
149 | packet_set_connection(pout[0], pin[1]); | |
8efc0c15 | 150 | |
5260325f | 151 | return 1; |
152 | } | |
8efc0c15 | 153 | |
5260325f | 154 | /* |
155 | * Creates a (possibly privileged) socket for use as the ssh connection. | |
156 | */ | |
157 | int | |
48e671d5 | 158 | ssh_create_socket(uid_t original_real_uid, int privileged, int family) |
8efc0c15 | 159 | { |
5260325f | 160 | int sock; |
161 | ||
aa3378df | 162 | /* |
163 | * If we are running as root and want to connect to a privileged | |
164 | * port, bind our own socket to a privileged port. | |
165 | */ | |
5260325f | 166 | if (privileged) { |
167 | int p = IPPORT_RESERVED - 1; | |
48e671d5 | 168 | sock = rresvport_af(&p, family); |
5260325f | 169 | if (sock < 0) |
c8d54615 | 170 | error("rresvport: af=%d %.100s", family, strerror(errno)); |
171 | else | |
172 | debug("Allocated local port %d.", p); | |
5260325f | 173 | } else { |
95f1eccc | 174 | /* |
175 | * Just create an ordinary socket on arbitrary port. We use | |
176 | * the user's uid to create the socket. | |
177 | */ | |
5260325f | 178 | temporarily_use_uid(original_real_uid); |
48e671d5 | 179 | sock = socket(family, SOCK_STREAM, 0); |
5260325f | 180 | if (sock < 0) |
48e671d5 | 181 | error("socket: %.100s", strerror(errno)); |
5260325f | 182 | restore_uid(); |
183 | } | |
184 | return sock; | |
8efc0c15 | 185 | } |
186 | ||
5260325f | 187 | /* |
48e671d5 | 188 | * Opens a TCP/IP connection to the remote server on the given host. |
189 | * The address of the remote host will be returned in hostaddr. | |
190 | * If port is 0, the default port will be used. If anonymous is zero, | |
5260325f | 191 | * a privileged port will be allocated to make the connection. |
192 | * This requires super-user privileges if anonymous is false. | |
193 | * Connection_attempts specifies the maximum number of tries (one per | |
194 | * second). If proxy_command is non-NULL, it specifies the command (with %h | |
195 | * and %p substituted for host and port, respectively) to use to contact | |
196 | * the daemon. | |
197 | */ | |
198 | int | |
48e671d5 | 199 | ssh_connect(const char *host, struct sockaddr_storage * hostaddr, |
57112b5a | 200 | u_short port, int connection_attempts, |
5260325f | 201 | int anonymous, uid_t original_real_uid, |
202 | const char *proxy_command) | |
8efc0c15 | 203 | { |
48e671d5 | 204 | int sock = -1, attempt; |
5260325f | 205 | struct servent *sp; |
48e671d5 | 206 | struct addrinfo hints, *ai, *aitop; |
207 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
208 | int gaierr; | |
5260325f | 209 | struct linger linger; |
210 | ||
211 | debug("ssh_connect: getuid %d geteuid %d anon %d", | |
212 | (int) getuid(), (int) geteuid(), anonymous); | |
213 | ||
214 | /* Get default port if port has not been set. */ | |
215 | if (port == 0) { | |
216 | sp = getservbyname(SSH_SERVICE_NAME, "tcp"); | |
217 | if (sp) | |
218 | port = ntohs(sp->s_port); | |
219 | else | |
220 | port = SSH_DEFAULT_PORT; | |
8efc0c15 | 221 | } |
5260325f | 222 | /* If a proxy command is given, connect using it. */ |
223 | if (proxy_command != NULL) | |
224 | return ssh_proxy_connect(host, port, original_real_uid, proxy_command); | |
225 | ||
226 | /* No proxy command. */ | |
227 | ||
48e671d5 | 228 | memset(&hints, 0, sizeof(hints)); |
229 | hints.ai_family = IPv4or6; | |
230 | hints.ai_socktype = SOCK_STREAM; | |
231 | snprintf(strport, sizeof strport, "%d", port); | |
232 | if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0) | |
233 | fatal("%s: %.100s: %s", __progname, host, | |
234 | gai_strerror(gaierr)); | |
5260325f | 235 | |
95f1eccc | 236 | /* |
237 | * Try to connect several times. On some machines, the first time | |
238 | * will sometimes fail. In general socket code appears to behave | |
239 | * quite magically on many machines. | |
240 | */ | |
5260325f | 241 | for (attempt = 0; attempt < connection_attempts; attempt++) { |
242 | if (attempt > 0) | |
243 | debug("Trying again..."); | |
244 | ||
48e671d5 | 245 | /* Loop through addresses for this host, and try each one in |
6ae2364d | 246 | sequence until the connection succeeds. */ |
48e671d5 | 247 | for (ai = aitop; ai; ai = ai->ai_next) { |
248 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
249 | continue; | |
250 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
251 | ntop, sizeof(ntop), strport, sizeof(strport), | |
252 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
253 | error("ssh_connect: getnameinfo failed"); | |
254 | continue; | |
255 | } | |
256 | debug("Connecting to %.200s [%.100s] port %s.", | |
257 | host, ntop, strport); | |
258 | ||
259 | /* Create a socket for connecting. */ | |
6ae2364d | 260 | sock = ssh_create_socket(original_real_uid, |
48e671d5 | 261 | !anonymous && geteuid() == 0 && port < IPPORT_RESERVED, |
262 | ai->ai_family); | |
263 | if (sock < 0) | |
264 | continue; | |
265 | ||
266 | /* Connect to the host. We use the user's uid in the | |
267 | * hope that it will help with tcp_wrappers showing | |
268 | * the remote uid as root. | |
aa3378df | 269 | */ |
5260325f | 270 | temporarily_use_uid(original_real_uid); |
48e671d5 | 271 | if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) { |
272 | /* Successful connection. */ | |
273 | memcpy(hostaddr, ai->ai_addr, sizeof(*(ai->ai_addr))); | |
5260325f | 274 | restore_uid(); |
275 | break; | |
48e671d5 | 276 | } else { |
5260325f | 277 | debug("connect: %.100s", strerror(errno)); |
278 | restore_uid(); | |
aa3378df | 279 | /* |
280 | * Close the failed socket; there appear to | |
281 | * be some problems when reusing a socket for | |
282 | * which connect() has already returned an | |
283 | * error. | |
284 | */ | |
5260325f | 285 | shutdown(sock, SHUT_RDWR); |
286 | close(sock); | |
287 | } | |
8efc0c15 | 288 | } |
48e671d5 | 289 | if (ai) |
290 | break; /* Successful connection. */ | |
8efc0c15 | 291 | |
5260325f | 292 | /* Sleep a moment before retrying. */ |
293 | sleep(1); | |
294 | } | |
48e671d5 | 295 | |
296 | freeaddrinfo(aitop); | |
297 | ||
5260325f | 298 | /* Return failure if we didn't get a successful connection. */ |
299 | if (attempt >= connection_attempts) | |
300 | return 0; | |
8efc0c15 | 301 | |
5260325f | 302 | debug("Connection established."); |
8efc0c15 | 303 | |
aa3378df | 304 | /* |
305 | * Set socket options. We would like the socket to disappear as soon | |
306 | * as it has been closed for whatever reason. | |
307 | */ | |
308 | /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 309 | linger.l_onoff = 1; |
310 | linger.l_linger = 5; | |
311 | setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
8efc0c15 | 312 | |
5260325f | 313 | /* Set the connection. */ |
314 | packet_set_connection(sock, sock); | |
8efc0c15 | 315 | |
5260325f | 316 | return 1; |
8efc0c15 | 317 | } |
318 | ||
5260325f | 319 | /* |
320 | * Checks if the user has an authentication agent, and if so, tries to | |
321 | * authenticate using the agent. | |
322 | */ | |
8efc0c15 | 323 | int |
324 | try_agent_authentication() | |
325 | { | |
5260325f | 326 | int status, type; |
327 | char *comment; | |
328 | AuthenticationConnection *auth; | |
329 | unsigned char response[16]; | |
330 | unsigned int i; | |
331 | BIGNUM *e, *n, *challenge; | |
332 | ||
333 | /* Get connection to the agent. */ | |
334 | auth = ssh_get_authentication_connection(); | |
335 | if (!auth) | |
336 | return 0; | |
337 | ||
338 | e = BN_new(); | |
339 | n = BN_new(); | |
340 | challenge = BN_new(); | |
341 | ||
342 | /* Loop through identities served by the agent. */ | |
343 | for (status = ssh_get_first_identity(auth, e, n, &comment); | |
344 | status; | |
345 | status = ssh_get_next_identity(auth, e, n, &comment)) { | |
346 | int plen, clen; | |
347 | ||
348 | /* Try this identity. */ | |
349 | debug("Trying RSA authentication via agent with '%.100s'", comment); | |
350 | xfree(comment); | |
351 | ||
352 | /* Tell the server that we are willing to authenticate using this key. */ | |
353 | packet_start(SSH_CMSG_AUTH_RSA); | |
354 | packet_put_bignum(n); | |
355 | packet_send(); | |
356 | packet_write_wait(); | |
357 | ||
358 | /* Wait for server's response. */ | |
359 | type = packet_read(&plen); | |
360 | ||
361 | /* The server sends failure if it doesn\'t like our key or | |
362 | does not support RSA authentication. */ | |
363 | if (type == SSH_SMSG_FAILURE) { | |
364 | debug("Server refused our key."); | |
365 | continue; | |
366 | } | |
367 | /* Otherwise it should have sent a challenge. */ | |
368 | if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) | |
369 | packet_disconnect("Protocol error during RSA authentication: %d", | |
370 | type); | |
8efc0c15 | 371 | |
5260325f | 372 | packet_get_bignum(challenge, &clen); |
8efc0c15 | 373 | |
5260325f | 374 | packet_integrity_check(plen, clen, type); |
8efc0c15 | 375 | |
5260325f | 376 | debug("Received RSA challenge from server."); |
377 | ||
378 | /* Ask the agent to decrypt the challenge. */ | |
379 | if (!ssh_decrypt_challenge(auth, e, n, challenge, | |
380 | session_id, 1, response)) { | |
381 | /* The agent failed to authenticate this identifier although it | |
382 | advertised it supports this. Just return a wrong value. */ | |
383 | log("Authentication agent failed to decrypt challenge."); | |
384 | memset(response, 0, sizeof(response)); | |
385 | } | |
386 | debug("Sending response to RSA challenge."); | |
387 | ||
388 | /* Send the decrypted challenge back to the server. */ | |
389 | packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); | |
390 | for (i = 0; i < 16; i++) | |
391 | packet_put_char(response[i]); | |
392 | packet_send(); | |
393 | packet_write_wait(); | |
394 | ||
395 | /* Wait for response from the server. */ | |
396 | type = packet_read(&plen); | |
397 | ||
398 | /* The server returns success if it accepted the authentication. */ | |
399 | if (type == SSH_SMSG_SUCCESS) { | |
400 | debug("RSA authentication accepted by server."); | |
401 | BN_clear_free(e); | |
402 | BN_clear_free(n); | |
403 | BN_clear_free(challenge); | |
404 | return 1; | |
405 | } | |
406 | /* Otherwise it should return failure. */ | |
407 | if (type != SSH_SMSG_FAILURE) | |
408 | packet_disconnect("Protocol error waiting RSA auth response: %d", | |
409 | type); | |
410 | } | |
411 | ||
412 | BN_clear_free(e); | |
413 | BN_clear_free(n); | |
414 | BN_clear_free(challenge); | |
8efc0c15 | 415 | |
5260325f | 416 | debug("RSA authentication using agent refused."); |
417 | return 0; | |
418 | } | |
8efc0c15 | 419 | |
5260325f | 420 | /* |
421 | * Computes the proper response to a RSA challenge, and sends the response to | |
422 | * the server. | |
423 | */ | |
8efc0c15 | 424 | void |
5260325f | 425 | respond_to_rsa_challenge(BIGNUM * challenge, RSA * prv) |
8efc0c15 | 426 | { |
5260325f | 427 | unsigned char buf[32], response[16]; |
428 | MD5_CTX md; | |
429 | int i, len; | |
430 | ||
431 | /* Decrypt the challenge using the private key. */ | |
432 | rsa_private_decrypt(challenge, challenge, prv); | |
433 | ||
434 | /* Compute the response. */ | |
435 | /* The response is MD5 of decrypted challenge plus session id. */ | |
436 | len = BN_num_bytes(challenge); | |
437 | if (len <= 0 || len > sizeof(buf)) | |
438 | packet_disconnect("respond_to_rsa_challenge: bad challenge length %d", | |
439 | len); | |
440 | ||
441 | memset(buf, 0, sizeof(buf)); | |
442 | BN_bn2bin(challenge, buf + sizeof(buf) - len); | |
443 | MD5_Init(&md); | |
444 | MD5_Update(&md, buf, 32); | |
445 | MD5_Update(&md, session_id, 16); | |
446 | MD5_Final(response, &md); | |
447 | ||
448 | debug("Sending response to host key RSA challenge."); | |
449 | ||
450 | /* Send the response back to the server. */ | |
451 | packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); | |
452 | for (i = 0; i < 16; i++) | |
453 | packet_put_char(response[i]); | |
454 | packet_send(); | |
455 | packet_write_wait(); | |
8efc0c15 | 456 | |
5260325f | 457 | memset(buf, 0, sizeof(buf)); |
458 | memset(response, 0, sizeof(response)); | |
459 | memset(&md, 0, sizeof(md)); | |
460 | } | |
8efc0c15 | 461 | |
5260325f | 462 | /* |
463 | * Checks if the user has authentication file, and if so, tries to authenticate | |
464 | * the user using it. | |
465 | */ | |
8efc0c15 | 466 | int |
57112b5a | 467 | try_rsa_authentication(const char *authfile) |
8efc0c15 | 468 | { |
5260325f | 469 | BIGNUM *challenge; |
470 | RSA *private_key; | |
471 | RSA *public_key; | |
472 | char *passphrase, *comment; | |
473 | int type, i; | |
474 | int plen, clen; | |
475 | ||
476 | /* Try to load identification for the authentication key. */ | |
477 | public_key = RSA_new(); | |
478 | if (!load_public_key(authfile, public_key, &comment)) { | |
479 | RSA_free(public_key); | |
57112b5a | 480 | /* Could not load it. Fail. */ |
481 | return 0; | |
8efc0c15 | 482 | } |
5260325f | 483 | debug("Trying RSA authentication with key '%.100s'", comment); |
484 | ||
485 | /* Tell the server that we are willing to authenticate using this key. */ | |
486 | packet_start(SSH_CMSG_AUTH_RSA); | |
487 | packet_put_bignum(public_key->n); | |
488 | packet_send(); | |
489 | packet_write_wait(); | |
490 | ||
491 | /* We no longer need the public key. */ | |
492 | RSA_free(public_key); | |
493 | ||
494 | /* Wait for server's response. */ | |
495 | type = packet_read(&plen); | |
496 | ||
aa3378df | 497 | /* |
498 | * The server responds with failure if it doesn\'t like our key or | |
499 | * doesn\'t support RSA authentication. | |
500 | */ | |
5260325f | 501 | if (type == SSH_SMSG_FAILURE) { |
502 | debug("Server refused our key."); | |
503 | xfree(comment); | |
57112b5a | 504 | return 0; |
8efc0c15 | 505 | } |
5260325f | 506 | /* Otherwise, the server should respond with a challenge. */ |
507 | if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) | |
508 | packet_disconnect("Protocol error during RSA authentication: %d", type); | |
509 | ||
510 | /* Get the challenge from the packet. */ | |
511 | challenge = BN_new(); | |
512 | packet_get_bignum(challenge, &clen); | |
513 | ||
514 | packet_integrity_check(plen, clen, type); | |
515 | ||
516 | debug("Received RSA challenge from server."); | |
517 | ||
518 | private_key = RSA_new(); | |
aa3378df | 519 | /* |
520 | * Load the private key. Try first with empty passphrase; if it | |
521 | * fails, ask for a passphrase. | |
522 | */ | |
5260325f | 523 | if (!load_private_key(authfile, "", private_key, NULL)) { |
524 | char buf[300]; | |
525 | snprintf(buf, sizeof buf, "Enter passphrase for RSA key '%.100s': ", | |
a408af76 | 526 | comment); |
5260325f | 527 | if (!options.batch_mode) |
528 | passphrase = read_passphrase(buf, 0); | |
529 | else { | |
530 | debug("Will not query passphrase for %.100s in batch mode.", | |
531 | comment); | |
532 | passphrase = xstrdup(""); | |
533 | } | |
8efc0c15 | 534 | |
5260325f | 535 | /* Load the authentication file using the pasphrase. */ |
536 | if (!load_private_key(authfile, passphrase, private_key, NULL)) { | |
537 | memset(passphrase, 0, strlen(passphrase)); | |
538 | xfree(passphrase); | |
539 | error("Bad passphrase."); | |
540 | ||
541 | /* Send a dummy response packet to avoid protocol error. */ | |
542 | packet_start(SSH_CMSG_AUTH_RSA_RESPONSE); | |
543 | for (i = 0; i < 16; i++) | |
544 | packet_put_char(0); | |
545 | packet_send(); | |
546 | packet_write_wait(); | |
547 | ||
548 | /* Expect the server to reject it... */ | |
549 | packet_read_expect(&plen, SSH_SMSG_FAILURE); | |
550 | xfree(comment); | |
551 | return 0; | |
552 | } | |
553 | /* Destroy the passphrase. */ | |
554 | memset(passphrase, 0, strlen(passphrase)); | |
555 | xfree(passphrase); | |
556 | } | |
557 | /* We no longer need the comment. */ | |
558 | xfree(comment); | |
559 | ||
560 | /* Compute and send a response to the challenge. */ | |
561 | respond_to_rsa_challenge(challenge, private_key); | |
562 | ||
563 | /* Destroy the private key. */ | |
564 | RSA_free(private_key); | |
8efc0c15 | 565 | |
5260325f | 566 | /* We no longer need the challenge. */ |
567 | BN_clear_free(challenge); | |
568 | ||
569 | /* Wait for response from the server. */ | |
570 | type = packet_read(&plen); | |
571 | if (type == SSH_SMSG_SUCCESS) { | |
572 | debug("RSA authentication accepted by server."); | |
573 | return 1; | |
574 | } | |
575 | if (type != SSH_SMSG_FAILURE) | |
576 | packet_disconnect("Protocol error waiting RSA auth response: %d", type); | |
577 | debug("RSA authentication refused."); | |
578 | return 0; | |
579 | } | |
8efc0c15 | 580 | |
5260325f | 581 | /* |
582 | * Tries to authenticate the user using combined rhosts or /etc/hosts.equiv | |
583 | * authentication and RSA host authentication. | |
584 | */ | |
8efc0c15 | 585 | int |
5260325f | 586 | try_rhosts_rsa_authentication(const char *local_user, RSA * host_key) |
8efc0c15 | 587 | { |
5260325f | 588 | int type; |
589 | BIGNUM *challenge; | |
590 | int plen, clen; | |
591 | ||
592 | debug("Trying rhosts or /etc/hosts.equiv with RSA host authentication."); | |
593 | ||
594 | /* Tell the server that we are willing to authenticate using this key. */ | |
595 | packet_start(SSH_CMSG_AUTH_RHOSTS_RSA); | |
596 | packet_put_string(local_user, strlen(local_user)); | |
597 | packet_put_int(BN_num_bits(host_key->n)); | |
598 | packet_put_bignum(host_key->e); | |
599 | packet_put_bignum(host_key->n); | |
600 | packet_send(); | |
601 | packet_write_wait(); | |
602 | ||
603 | /* Wait for server's response. */ | |
604 | type = packet_read(&plen); | |
605 | ||
606 | /* The server responds with failure if it doesn't admit our | |
607 | .rhosts authentication or doesn't know our host key. */ | |
608 | if (type == SSH_SMSG_FAILURE) { | |
609 | debug("Server refused our rhosts authentication or host key."); | |
610 | return 0; | |
611 | } | |
612 | /* Otherwise, the server should respond with a challenge. */ | |
613 | if (type != SSH_SMSG_AUTH_RSA_CHALLENGE) | |
614 | packet_disconnect("Protocol error during RSA authentication: %d", type); | |
615 | ||
616 | /* Get the challenge from the packet. */ | |
617 | challenge = BN_new(); | |
618 | packet_get_bignum(challenge, &clen); | |
619 | ||
620 | packet_integrity_check(plen, clen, type); | |
621 | ||
622 | debug("Received RSA challenge for host key from server."); | |
623 | ||
624 | /* Compute a response to the challenge. */ | |
625 | respond_to_rsa_challenge(challenge, host_key); | |
626 | ||
627 | /* We no longer need the challenge. */ | |
628 | BN_clear_free(challenge); | |
629 | ||
630 | /* Wait for response from the server. */ | |
631 | type = packet_read(&plen); | |
632 | if (type == SSH_SMSG_SUCCESS) { | |
633 | debug("Rhosts or /etc/hosts.equiv with RSA host authentication accepted by server."); | |
634 | return 1; | |
635 | } | |
636 | if (type != SSH_SMSG_FAILURE) | |
637 | packet_disconnect("Protocol error waiting RSA auth response: %d", type); | |
638 | debug("Rhosts or /etc/hosts.equiv with RSA host authentication refused."); | |
639 | return 0; | |
8efc0c15 | 640 | } |
641 | ||
642 | #ifdef KRB4 | |
5260325f | 643 | int |
644 | try_kerberos_authentication() | |
8efc0c15 | 645 | { |
5260325f | 646 | KTEXT_ST auth; /* Kerberos data */ |
647 | char *reply; | |
648 | char inst[INST_SZ]; | |
649 | char *realm; | |
650 | CREDENTIALS cred; | |
651 | int r, type, plen; | |
610cd5c6 | 652 | socklen_t slen; |
5260325f | 653 | Key_schedule schedule; |
654 | u_long checksum, cksum; | |
655 | MSG_DAT msg_data; | |
656 | struct sockaddr_in local, foreign; | |
657 | struct stat st; | |
658 | ||
659 | /* Don't do anything if we don't have any tickets. */ | |
660 | if (stat(tkt_string(), &st) < 0) | |
661 | return 0; | |
662 | ||
663 | strncpy(inst, (char *) krb_get_phost(get_canonical_hostname()), INST_SZ); | |
664 | ||
665 | realm = (char *) krb_realmofhost(get_canonical_hostname()); | |
666 | if (!realm) { | |
667 | debug("Kerberos V4: no realm for %s", get_canonical_hostname()); | |
668 | return 0; | |
669 | } | |
670 | /* This can really be anything. */ | |
671 | checksum = (u_long) getpid(); | |
672 | ||
673 | r = krb_mk_req(&auth, KRB4_SERVICE_NAME, inst, realm, checksum); | |
674 | if (r != KSUCCESS) { | |
675 | debug("Kerberos V4 krb_mk_req failed: %s", krb_err_txt[r]); | |
676 | return 0; | |
677 | } | |
678 | /* Get session key to decrypt the server's reply with. */ | |
679 | r = krb_get_cred(KRB4_SERVICE_NAME, inst, realm, &cred); | |
680 | if (r != KSUCCESS) { | |
681 | debug("get_cred failed: %s", krb_err_txt[r]); | |
682 | return 0; | |
683 | } | |
684 | des_key_sched((des_cblock *) cred.session, schedule); | |
685 | ||
686 | /* Send authentication info to server. */ | |
687 | packet_start(SSH_CMSG_AUTH_KERBEROS); | |
688 | packet_put_string((char *) auth.dat, auth.length); | |
689 | packet_send(); | |
690 | packet_write_wait(); | |
691 | ||
692 | /* Zero the buffer. */ | |
693 | (void) memset(auth.dat, 0, MAX_KTXT_LEN); | |
694 | ||
610cd5c6 | 695 | slen = sizeof(local); |
5260325f | 696 | memset(&local, 0, sizeof(local)); |
697 | if (getsockname(packet_get_connection_in(), | |
610cd5c6 | 698 | (struct sockaddr *) & local, &slen) < 0) |
5260325f | 699 | debug("getsockname failed: %s", strerror(errno)); |
700 | ||
610cd5c6 | 701 | slen = sizeof(foreign); |
5260325f | 702 | memset(&foreign, 0, sizeof(foreign)); |
703 | if (getpeername(packet_get_connection_in(), | |
610cd5c6 | 704 | (struct sockaddr *) & foreign, &slen) < 0) { |
5260325f | 705 | debug("getpeername failed: %s", strerror(errno)); |
706 | fatal_cleanup(); | |
707 | } | |
708 | /* Get server reply. */ | |
709 | type = packet_read(&plen); | |
710 | switch (type) { | |
711 | case SSH_SMSG_FAILURE: | |
712 | /* Should really be SSH_SMSG_AUTH_KERBEROS_FAILURE */ | |
713 | debug("Kerberos V4 authentication failed."); | |
714 | return 0; | |
715 | break; | |
716 | ||
717 | case SSH_SMSG_AUTH_KERBEROS_RESPONSE: | |
718 | /* SSH_SMSG_AUTH_KERBEROS_SUCCESS */ | |
719 | debug("Kerberos V4 authentication accepted."); | |
720 | ||
721 | /* Get server's response. */ | |
722 | reply = packet_get_string((unsigned int *) &auth.length); | |
723 | memcpy(auth.dat, reply, auth.length); | |
724 | xfree(reply); | |
725 | ||
726 | packet_integrity_check(plen, 4 + auth.length, type); | |
727 | ||
aa3378df | 728 | /* |
729 | * If his response isn't properly encrypted with the session | |
730 | * key, and the decrypted checksum fails to match, he's | |
731 | * bogus. Bail out. | |
732 | */ | |
5260325f | 733 | r = krb_rd_priv(auth.dat, auth.length, schedule, &cred.session, |
734 | &foreign, &local, &msg_data); | |
735 | if (r != KSUCCESS) { | |
736 | debug("Kerberos V4 krb_rd_priv failed: %s", krb_err_txt[r]); | |
737 | packet_disconnect("Kerberos V4 challenge failed!"); | |
738 | } | |
739 | /* Fetch the (incremented) checksum that we supplied in the request. */ | |
740 | (void) memcpy((char *) &cksum, (char *) msg_data.app_data, sizeof(cksum)); | |
741 | cksum = ntohl(cksum); | |
742 | ||
743 | /* If it matches, we're golden. */ | |
744 | if (cksum == checksum + 1) { | |
745 | debug("Kerberos V4 challenge successful."); | |
746 | return 1; | |
747 | } else | |
748 | packet_disconnect("Kerberos V4 challenge failed!"); | |
749 | break; | |
750 | ||
751 | default: | |
752 | packet_disconnect("Protocol error on Kerberos V4 response: %d", type); | |
753 | } | |
754 | return 0; | |
8efc0c15 | 755 | } |
5260325f | 756 | |
8efc0c15 | 757 | #endif /* KRB4 */ |
758 | ||
759 | #ifdef AFS | |
5260325f | 760 | int |
761 | send_kerberos_tgt() | |
8efc0c15 | 762 | { |
5260325f | 763 | CREDENTIALS *creds; |
764 | char pname[ANAME_SZ], pinst[INST_SZ], prealm[REALM_SZ]; | |
765 | int r, type, plen; | |
610cd5c6 | 766 | char buffer[8192]; |
5260325f | 767 | struct stat st; |
768 | ||
769 | /* Don't do anything if we don't have any tickets. */ | |
770 | if (stat(tkt_string(), &st) < 0) | |
771 | return 0; | |
772 | ||
773 | creds = xmalloc(sizeof(*creds)); | |
774 | ||
775 | if ((r = krb_get_tf_fullname(TKT_FILE, pname, pinst, prealm)) != KSUCCESS) { | |
776 | debug("Kerberos V4 tf_fullname failed: %s", krb_err_txt[r]); | |
777 | return 0; | |
778 | } | |
779 | if ((r = krb_get_cred("krbtgt", prealm, prealm, creds)) != GC_OK) { | |
780 | debug("Kerberos V4 get_cred failed: %s", krb_err_txt[r]); | |
781 | return 0; | |
782 | } | |
783 | if (time(0) > krb_life_to_time(creds->issue_date, creds->lifetime)) { | |
784 | debug("Kerberos V4 ticket expired: %s", TKT_FILE); | |
785 | return 0; | |
786 | } | |
610cd5c6 | 787 | creds_to_radix(creds, (unsigned char *)buffer); |
5260325f | 788 | xfree(creds); |
789 | ||
790 | packet_start(SSH_CMSG_HAVE_KERBEROS_TGT); | |
610cd5c6 | 791 | packet_put_string(buffer, strlen(buffer)); |
5260325f | 792 | packet_send(); |
793 | packet_write_wait(); | |
794 | ||
795 | type = packet_read(&plen); | |
796 | ||
797 | if (type == SSH_SMSG_FAILURE) | |
798 | debug("Kerberos TGT for realm %s rejected.", prealm); | |
799 | else if (type != SSH_SMSG_SUCCESS) | |
800 | packet_disconnect("Protocol error on Kerberos TGT response: %d", type); | |
801 | ||
802 | return 1; | |
8efc0c15 | 803 | } |
804 | ||
5260325f | 805 | void |
806 | send_afs_tokens(void) | |
8efc0c15 | 807 | { |
5260325f | 808 | CREDENTIALS creds; |
809 | struct ViceIoctl parms; | |
810 | struct ClearToken ct; | |
811 | int i, type, len, plen; | |
812 | char buf[2048], *p, *server_cell; | |
610cd5c6 | 813 | char buffer[8192]; |
5260325f | 814 | |
815 | /* Move over ktc_GetToken, here's something leaner. */ | |
816 | for (i = 0; i < 100; i++) { /* just in case */ | |
817 | parms.in = (char *) &i; | |
818 | parms.in_size = sizeof(i); | |
819 | parms.out = buf; | |
820 | parms.out_size = sizeof(buf); | |
821 | if (k_pioctl(0, VIOCGETTOK, &parms, 0) != 0) | |
822 | break; | |
823 | p = buf; | |
824 | ||
825 | /* Get secret token. */ | |
826 | memcpy(&creds.ticket_st.length, p, sizeof(unsigned int)); | |
827 | if (creds.ticket_st.length > MAX_KTXT_LEN) | |
828 | break; | |
829 | p += sizeof(unsigned int); | |
830 | memcpy(creds.ticket_st.dat, p, creds.ticket_st.length); | |
831 | p += creds.ticket_st.length; | |
832 | ||
833 | /* Get clear token. */ | |
834 | memcpy(&len, p, sizeof(len)); | |
835 | if (len != sizeof(struct ClearToken)) | |
836 | break; | |
837 | p += sizeof(len); | |
838 | memcpy(&ct, p, len); | |
839 | p += len; | |
840 | p += sizeof(len); /* primary flag */ | |
841 | server_cell = p; | |
842 | ||
843 | /* Flesh out our credentials. */ | |
844 | strlcpy(creds.service, "afs", sizeof creds.service); | |
845 | creds.instance[0] = '\0'; | |
846 | strlcpy(creds.realm, server_cell, REALM_SZ); | |
847 | memcpy(creds.session, ct.HandShakeKey, DES_KEY_SZ); | |
848 | creds.issue_date = ct.BeginTimestamp; | |
849 | creds.lifetime = krb_time_to_life(creds.issue_date, ct.EndTimestamp); | |
850 | creds.kvno = ct.AuthHandle; | |
851 | snprintf(creds.pname, sizeof(creds.pname), "AFS ID %d", ct.ViceId); | |
852 | creds.pinst[0] = '\0'; | |
853 | ||
854 | /* Encode token, ship it off. */ | |
610cd5c6 | 855 | if (!creds_to_radix(&creds, (unsigned char*) buffer)) |
5260325f | 856 | break; |
857 | packet_start(SSH_CMSG_HAVE_AFS_TOKEN); | |
610cd5c6 | 858 | packet_put_string(buffer, strlen(buffer)); |
5260325f | 859 | packet_send(); |
860 | packet_write_wait(); | |
861 | ||
862 | /* Roger, Roger. Clearance, Clarence. What's your vector, | |
863 | Victor? */ | |
864 | type = packet_read(&plen); | |
865 | ||
866 | if (type == SSH_SMSG_FAILURE) | |
867 | debug("AFS token for cell %s rejected.", server_cell); | |
868 | else if (type != SSH_SMSG_SUCCESS) | |
869 | packet_disconnect("Protocol error on AFS token response: %d", type); | |
870 | } | |
8efc0c15 | 871 | } |
8efc0c15 | 872 | |
5260325f | 873 | #endif /* AFS */ |
8efc0c15 | 874 | |
57112b5a | 875 | /* |
876 | * Tries to authenticate with any string-based challenge/response system. | |
877 | * Note that the client code is not tied to s/key or TIS. | |
878 | */ | |
879 | int | |
880 | try_skey_authentication() | |
881 | { | |
610cd5c6 | 882 | int type, i; |
883 | int payload_len; | |
884 | unsigned int clen; | |
57112b5a | 885 | char *challenge, *response; |
886 | ||
887 | debug("Doing skey authentication."); | |
888 | ||
889 | /* request a challenge */ | |
890 | packet_start(SSH_CMSG_AUTH_TIS); | |
891 | packet_send(); | |
892 | packet_write_wait(); | |
893 | ||
894 | type = packet_read(&payload_len); | |
895 | if (type != SSH_SMSG_FAILURE && | |
896 | type != SSH_SMSG_AUTH_TIS_CHALLENGE) { | |
897 | packet_disconnect("Protocol error: got %d in response " | |
898 | "to skey-auth", type); | |
899 | } | |
900 | if (type != SSH_SMSG_AUTH_TIS_CHALLENGE) { | |
901 | debug("No challenge for skey authentication."); | |
902 | return 0; | |
903 | } | |
610cd5c6 | 904 | challenge = packet_get_string(&clen); |
905 | packet_integrity_check(payload_len, (4 + clen), type); | |
57112b5a | 906 | if (options.cipher == SSH_CIPHER_NONE) |
907 | log("WARNING: Encryption is disabled! " | |
908 | "Reponse will be transmitted in clear text."); | |
909 | fprintf(stderr, "%s\n", challenge); | |
c8d54615 | 910 | xfree(challenge); |
57112b5a | 911 | fflush(stderr); |
912 | for (i = 0; i < options.number_of_password_prompts; i++) { | |
913 | if (i != 0) | |
914 | error("Permission denied, please try again."); | |
915 | response = read_passphrase("Response: ", 0); | |
916 | packet_start(SSH_CMSG_AUTH_TIS_RESPONSE); | |
917 | packet_put_string(response, strlen(response)); | |
918 | memset(response, 0, strlen(response)); | |
919 | xfree(response); | |
920 | packet_send(); | |
921 | packet_write_wait(); | |
922 | type = packet_read(&payload_len); | |
923 | if (type == SSH_SMSG_SUCCESS) | |
924 | return 1; | |
925 | if (type != SSH_SMSG_FAILURE) | |
926 | packet_disconnect("Protocol error: got %d in response " | |
927 | "to skey-auth-reponse", type); | |
928 | } | |
929 | /* failure */ | |
930 | return 0; | |
931 | } | |
932 | ||
933 | /* | |
934 | * Tries to authenticate with plain passwd authentication. | |
935 | */ | |
936 | int | |
937 | try_password_authentication(char *prompt) | |
938 | { | |
939 | int type, i, payload_len; | |
940 | char *password; | |
941 | ||
942 | debug("Doing password authentication."); | |
943 | if (options.cipher == SSH_CIPHER_NONE) | |
944 | log("WARNING: Encryption is disabled! Password will be transmitted in clear text."); | |
945 | for (i = 0; i < options.number_of_password_prompts; i++) { | |
946 | if (i != 0) | |
947 | error("Permission denied, please try again."); | |
948 | password = read_passphrase(prompt, 0); | |
949 | packet_start(SSH_CMSG_AUTH_PASSWORD); | |
950 | packet_put_string(password, strlen(password)); | |
951 | memset(password, 0, strlen(password)); | |
952 | xfree(password); | |
953 | packet_send(); | |
954 | packet_write_wait(); | |
955 | ||
956 | type = packet_read(&payload_len); | |
957 | if (type == SSH_SMSG_SUCCESS) | |
958 | return 1; | |
959 | if (type != SSH_SMSG_FAILURE) | |
960 | packet_disconnect("Protocol error: got %d in response to passwd auth", type); | |
961 | } | |
962 | /* failure */ | |
963 | return 0; | |
964 | } | |
965 | ||
8ce64345 | 966 | char * |
967 | chop(char *s) | |
968 | { | |
969 | char *t = s; | |
970 | while (*t) { | |
971 | if(*t == '\n' || *t == '\r') { | |
972 | *t = '\0'; | |
973 | return s; | |
974 | } | |
975 | t++; | |
976 | } | |
977 | return s; | |
978 | ||
979 | } | |
980 | ||
5260325f | 981 | /* |
982 | * Waits for the server identification string, and sends our own | |
983 | * identification string. | |
984 | */ | |
985 | void | |
986 | ssh_exchange_identification() | |
8efc0c15 | 987 | { |
5260325f | 988 | char buf[256], remote_version[256]; /* must be same size! */ |
a8be9f80 | 989 | int remote_major, remote_minor, i, mismatch; |
5260325f | 990 | int connection_in = packet_get_connection_in(); |
991 | int connection_out = packet_get_connection_out(); | |
5260325f | 992 | |
993 | /* Read other side\'s version identification. */ | |
994 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
c8d54615 | 995 | int len = read(connection_in, &buf[i], 1); |
996 | if (len < 0) | |
5260325f | 997 | fatal("ssh_exchange_identification: read: %.100s", strerror(errno)); |
c8d54615 | 998 | if (len != 1) |
999 | fatal("ssh_exchange_identification: Connection closed by remote host"); | |
5260325f | 1000 | if (buf[i] == '\r') { |
1001 | buf[i] = '\n'; | |
1002 | buf[i + 1] = 0; | |
8ce64345 | 1003 | continue; /**XXX wait for \n */ |
5260325f | 1004 | } |
1005 | if (buf[i] == '\n') { | |
1006 | buf[i + 1] = 0; | |
1007 | break; | |
1008 | } | |
8efc0c15 | 1009 | } |
5260325f | 1010 | buf[sizeof(buf) - 1] = 0; |
8ce64345 | 1011 | server_version_string = xstrdup(buf); |
5260325f | 1012 | |
aa3378df | 1013 | /* |
1014 | * Check that the versions match. In future this might accept | |
1015 | * several versions and set appropriate flags to handle them. | |
1016 | */ | |
8ce64345 | 1017 | if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n", |
1018 | &remote_major, &remote_minor, remote_version) != 3) | |
5260325f | 1019 | fatal("Bad remote protocol version identification: '%.100s'", buf); |
1020 | debug("Remote protocol version %d.%d, remote software version %.100s", | |
1021 | remote_major, remote_minor, remote_version); | |
1022 | ||
8ce64345 | 1023 | compat_datafellows(remote_version); |
a8be9f80 | 1024 | mismatch = 0; |
1025 | ||
1026 | switch(remote_major) { | |
1027 | case 1: | |
1028 | if (remote_minor == 99 && | |
1029 | (options.protocol & SSH_PROTO_2) && | |
1030 | !(options.protocol & SSH_PROTO_1_PREFERRED)) { | |
1031 | enable_compat20(); | |
1032 | break; | |
5260325f | 1033 | } |
a8be9f80 | 1034 | if (!(options.protocol & SSH_PROTO_1)) { |
1035 | mismatch = 1; | |
1036 | break; | |
1037 | } | |
1038 | if (remote_minor < 3) { | |
1039 | fatal("Remote machine has too old SSH software version."); | |
1040 | } else if (remote_minor == 3) { | |
1041 | /* We speak 1.3, too. */ | |
1042 | enable_compat13(); | |
1043 | if (options.forward_agent) { | |
1044 | log("Agent forwarding disabled for protocol 1.3"); | |
1045 | options.forward_agent = 0; | |
1046 | } | |
1047 | } | |
1048 | break; | |
1049 | case 2: | |
1050 | if (options.protocol & SSH_PROTO_2) { | |
1051 | enable_compat20(); | |
1052 | break; | |
1053 | } | |
1054 | /* FALLTHROUGH */ | |
6ae2364d | 1055 | default: |
a8be9f80 | 1056 | mismatch = 1; |
1057 | break; | |
8efc0c15 | 1058 | } |
a8be9f80 | 1059 | if (mismatch) |
5260325f | 1060 | fatal("Protocol major versions differ: %d vs. %d", |
a8be9f80 | 1061 | (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
1062 | remote_major); | |
1063 | ||
5260325f | 1064 | /* Send our own protocol version identification. */ |
1065 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", | |
a8be9f80 | 1066 | compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1, |
1067 | compat20 ? PROTOCOL_MINOR_2 : PROTOCOL_MINOR_1, | |
8ce64345 | 1068 | SSH_VERSION); |
a408af76 | 1069 | if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf)) |
5260325f | 1070 | fatal("write: %.100s", strerror(errno)); |
8ce64345 | 1071 | client_version_string = xstrdup(buf); |
1072 | chop(client_version_string); | |
1073 | chop(server_version_string); | |
1074 | debug("Local version string %.100s", client_version_string); | |
8efc0c15 | 1075 | } |
1076 | ||
5260325f | 1077 | int |
1078 | read_yes_or_no(const char *prompt, int defval) | |
8efc0c15 | 1079 | { |
5260325f | 1080 | char buf[1024]; |
1081 | FILE *f; | |
1082 | int retval = -1; | |
1083 | ||
1084 | if (isatty(0)) | |
1085 | f = stdin; | |
1086 | else | |
1087 | f = fopen("/dev/tty", "rw"); | |
1088 | ||
1089 | if (f == NULL) | |
1090 | return 0; | |
1091 | ||
1092 | fflush(stdout); | |
1093 | ||
1094 | while (1) { | |
1095 | fprintf(stderr, "%s", prompt); | |
1096 | if (fgets(buf, sizeof(buf), f) == NULL) { | |
1097 | /* Print a newline (the prompt probably didn\'t have one). */ | |
1098 | fprintf(stderr, "\n"); | |
1099 | strlcpy(buf, "no", sizeof buf); | |
1100 | } | |
1101 | /* Remove newline from response. */ | |
1102 | if (strchr(buf, '\n')) | |
1103 | *strchr(buf, '\n') = 0; | |
1104 | ||
1105 | if (buf[0] == 0) | |
1106 | retval = defval; | |
1107 | if (strcmp(buf, "yes") == 0) | |
1108 | retval = 1; | |
1109 | if (strcmp(buf, "no") == 0) | |
1110 | retval = 0; | |
1111 | ||
1112 | if (retval != -1) { | |
1113 | if (f != stdin) | |
1114 | fclose(f); | |
1115 | return retval; | |
1116 | } | |
8efc0c15 | 1117 | } |
8efc0c15 | 1118 | } |
1119 | ||
5260325f | 1120 | /* |
95f1eccc | 1121 | * check whether the supplied host key is valid, return only if ok. |
5260325f | 1122 | */ |
95f1eccc | 1123 | |
5260325f | 1124 | void |
4fe2af09 | 1125 | check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key) |
8efc0c15 | 1126 | { |
4fe2af09 | 1127 | Key *file_key; |
95f1eccc | 1128 | char *ip = NULL; |
5260325f | 1129 | char hostline[1000], *hostp; |
5260325f | 1130 | HostStatus host_status; |
1131 | HostStatus ip_status; | |
48e671d5 | 1132 | int local = 0, host_ip_differ = 0; |
20af321f | 1133 | int salen; |
48e671d5 | 1134 | char ntop[NI_MAXHOST]; |
1135 | ||
1136 | /* | |
1137 | * Force accepting of the host key for loopback/localhost. The | |
1138 | * problem is that if the home directory is NFS-mounted to multiple | |
1139 | * machines, localhost will refer to a different machine in each of | |
1140 | * them, and the user will get bogus HOST_CHANGED warnings. This | |
1141 | * essentially disables host authentication for localhost; however, | |
1142 | * this is probably not a real problem. | |
1143 | */ | |
1144 | switch (hostaddr->sa_family) { | |
1145 | case AF_INET: | |
1146 | local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET; | |
20af321f | 1147 | salen = sizeof(struct sockaddr_in); |
48e671d5 | 1148 | break; |
1149 | case AF_INET6: | |
1150 | local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr)); | |
20af321f | 1151 | salen = sizeof(struct sockaddr_in6); |
48e671d5 | 1152 | break; |
1153 | default: | |
1154 | local = 0; | |
20af321f | 1155 | salen = sizeof(struct sockaddr_storage); |
48e671d5 | 1156 | break; |
1157 | } | |
1158 | if (local) { | |
1159 | debug("Forcing accepting of host key for loopback/localhost."); | |
1160 | return; | |
1161 | } | |
5260325f | 1162 | |
57112b5a | 1163 | /* |
1164 | * Turn off check_host_ip for proxy connects, since | |
1165 | * we don't have the remote ip-address | |
1166 | */ | |
1167 | if (options.proxy_command != NULL && options.check_host_ip) | |
1168 | options.check_host_ip = 0; | |
1169 | ||
48e671d5 | 1170 | if (options.check_host_ip) { |
20af321f | 1171 | if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop), |
48e671d5 | 1172 | NULL, 0, NI_NUMERICHOST) != 0) |
1173 | fatal("check_host_key: getnameinfo failed"); | |
1174 | ip = xstrdup(ntop); | |
1175 | } | |
5260325f | 1176 | |
95f1eccc | 1177 | /* |
1178 | * Store the host key from the known host file in here so that we can | |
1179 | * compare it with the key for the IP address. | |
1180 | */ | |
4fe2af09 | 1181 | file_key = key_new(host_key->type); |
5260325f | 1182 | |
aa3378df | 1183 | /* |
1184 | * Check if the host key is present in the user\'s list of known | |
1185 | * hosts or in the systemwide list. | |
1186 | */ | |
4fe2af09 | 1187 | host_status = check_host_in_hostfile(options.user_hostfile, host, host_key, file_key); |
5260325f | 1188 | if (host_status == HOST_NEW) |
4fe2af09 | 1189 | host_status = check_host_in_hostfile(options.system_hostfile, host, host_key, file_key); |
aa3378df | 1190 | /* |
1191 | * Also perform check for the ip address, skip the check if we are | |
1192 | * localhost or the hostname was an ip address to begin with | |
1193 | */ | |
5260325f | 1194 | if (options.check_host_ip && !local && strcmp(host, ip)) { |
4fe2af09 | 1195 | Key *ip_key = key_new(host_key->type); |
1196 | ip_status = check_host_in_hostfile(options.user_hostfile, ip, host_key, ip_key); | |
5260325f | 1197 | |
1198 | if (ip_status == HOST_NEW) | |
4fe2af09 | 1199 | ip_status = check_host_in_hostfile(options.system_hostfile, ip, host_key, ip_key); |
5260325f | 1200 | if (host_status == HOST_CHANGED && |
4fe2af09 | 1201 | (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key))) |
5260325f | 1202 | host_ip_differ = 1; |
1203 | ||
4fe2af09 | 1204 | key_free(ip_key); |
5260325f | 1205 | } else |
1206 | ip_status = host_status; | |
1207 | ||
4fe2af09 | 1208 | key_free(file_key); |
5260325f | 1209 | |
1210 | switch (host_status) { | |
1211 | case HOST_OK: | |
1212 | /* The host is known and the key matches. */ | |
1213 | debug("Host '%.200s' is known and matches the host key.", host); | |
1214 | if (options.check_host_ip) { | |
1215 | if (ip_status == HOST_NEW) { | |
4fe2af09 | 1216 | if (!add_host_to_hostfile(options.user_hostfile, ip, host_key)) |
5260325f | 1217 | log("Failed to add the host key for IP address '%.30s' to the list of known hosts (%.30s).", |
1218 | ip, options.user_hostfile); | |
1219 | else | |
1220 | log("Warning: Permanently added host key for IP address '%.30s' to the list of known hosts.", | |
1221 | ip); | |
1222 | } else if (ip_status != HOST_OK) | |
1223 | log("Warning: the host key for '%.200s' differs from the key for the IP address '%.30s'", | |
1224 | host, ip); | |
1225 | } | |
1226 | break; | |
1227 | case HOST_NEW: | |
1228 | /* The host is new. */ | |
1229 | if (options.strict_host_key_checking == 1) { | |
1230 | /* User has requested strict host key checking. We will not add the host key | |
1231 | automatically. The only alternative left is to abort. */ | |
1232 | fatal("No host key is known for %.200s and you have requested strict checking.", host); | |
1233 | } else if (options.strict_host_key_checking == 2) { | |
1234 | /* The default */ | |
1235 | char prompt[1024]; | |
4fe2af09 | 1236 | char *fp = key_fingerprint(host_key); |
5260325f | 1237 | snprintf(prompt, sizeof(prompt), |
a408af76 | 1238 | "The authenticity of host '%.200s' can't be established.\n" |
4fe2af09 | 1239 | "Key fingerprint is %s.\n" |
a408af76 | 1240 | "Are you sure you want to continue connecting (yes/no)? ", |
4fe2af09 | 1241 | host, fp); |
5260325f | 1242 | if (!read_yes_or_no(prompt, -1)) |
1243 | fatal("Aborted by user!\n"); | |
1244 | } | |
1245 | if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) { | |
1246 | snprintf(hostline, sizeof(hostline), "%s,%s", host, ip); | |
1247 | hostp = hostline; | |
1248 | } else | |
1249 | hostp = host; | |
1250 | ||
1251 | /* If not in strict mode, add the key automatically to the local known_hosts file. */ | |
4fe2af09 | 1252 | if (!add_host_to_hostfile(options.user_hostfile, hostp, host_key)) |
5260325f | 1253 | log("Failed to add the host to the list of known hosts (%.500s).", |
1254 | options.user_hostfile); | |
1255 | else | |
1256 | log("Warning: Permanently added '%.200s' to the list of known hosts.", | |
1257 | hostp); | |
1258 | break; | |
1259 | case HOST_CHANGED: | |
1260 | if (options.check_host_ip && host_ip_differ) { | |
1261 | char *msg; | |
1262 | if (ip_status == HOST_NEW) | |
1263 | msg = "is unknown"; | |
1264 | else if (ip_status == HOST_OK) | |
1265 | msg = "is unchanged"; | |
1266 | else | |
1267 | msg = "has a different value"; | |
1268 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1269 | error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @"); | |
1270 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
1271 | error("The host key for %s has changed,", host); | |
1272 | error("and the key for the according IP address %s", ip); | |
1273 | error("%s. This could either mean that", msg); | |
1274 | error("DNS SPOOFING is happening or the IP address for the host"); | |
1275 | error("and its host key have changed at the same time"); | |
1276 | } | |
1277 | /* The host key has changed. */ | |
1278 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); | |
ae2f7af7 | 1279 | error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @"); |
5260325f | 1280 | error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@"); |
1281 | error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!"); | |
1282 | error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!"); | |
1283 | error("It is also possible that the host key has just been changed."); | |
1284 | error("Please contact your system administrator."); | |
1285 | error("Add correct host key in %.100s to get rid of this message.", | |
1286 | options.user_hostfile); | |
1287 | ||
aa3378df | 1288 | /* |
1289 | * If strict host key checking is in use, the user will have | |
1290 | * to edit the key manually and we can only abort. | |
1291 | */ | |
5260325f | 1292 | if (options.strict_host_key_checking) |
1293 | fatal("Host key for %.200s has changed and you have requested strict checking.", host); | |
1294 | ||
aa3378df | 1295 | /* |
1296 | * If strict host key checking has not been requested, allow | |
1297 | * the connection but without password authentication or | |
1298 | * agent forwarding. | |
1299 | */ | |
5260325f | 1300 | if (options.password_authentication) { |
1301 | error("Password authentication is disabled to avoid trojan horses."); | |
1302 | options.password_authentication = 0; | |
1303 | } | |
1304 | if (options.forward_agent) { | |
1305 | error("Agent forwarding is disabled to avoid trojan horses."); | |
1306 | options.forward_agent = 0; | |
1307 | } | |
aa3378df | 1308 | /* |
1309 | * XXX Should permit the user to change to use the new id. | |
1310 | * This could be done by converting the host key to an | |
1311 | * identifying sentence, tell that the host identifies itself | |
1312 | * by that sentence, and ask the user if he/she whishes to | |
1313 | * accept the authentication. | |
1314 | */ | |
5260325f | 1315 | break; |
1316 | } | |
5260325f | 1317 | if (options.check_host_ip) |
1318 | xfree(ip); | |
95f1eccc | 1319 | } |
4fe2af09 | 1320 | void |
1321 | check_rsa_host_key(char *host, struct sockaddr *hostaddr, RSA *host_key) | |
1322 | { | |
1323 | Key k; | |
1324 | k.type = KEY_RSA; | |
1325 | k.rsa = host_key; | |
1326 | check_host_key(host, hostaddr, &k); | |
1327 | } | |
95f1eccc | 1328 | |
8ce64345 | 1329 | /* |
1330 | * SSH2 key exchange | |
1331 | */ | |
1332 | void | |
1333 | ssh_kex2(char *host, struct sockaddr *hostaddr) | |
1334 | { | |
1335 | Kex *kex; | |
1336 | char *cprop[PROPOSAL_MAX]; | |
1337 | char *sprop[PROPOSAL_MAX]; | |
1338 | Buffer *client_kexinit; | |
1339 | Buffer *server_kexinit; | |
1340 | int payload_len, dlen; | |
1341 | unsigned int klen, kout; | |
1342 | char *ptr; | |
1343 | char *signature = NULL; | |
1344 | unsigned int slen; | |
1345 | char *server_host_key_blob = NULL; | |
1346 | Key *server_host_key; | |
1347 | unsigned int sbloblen; | |
1348 | DH *dh; | |
1349 | BIGNUM *dh_server_pub = 0; | |
1350 | BIGNUM *shared_secret = 0; | |
1351 | int i; | |
1352 | unsigned char *kbuf; | |
1353 | unsigned char *hash; | |
1354 | ||
1355 | /* KEXINIT */ | |
1356 | ||
1357 | debug("Sending KEX init."); | |
a8be9f80 | 1358 | if (options.ciphers != NULL) { |
6ae2364d | 1359 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
a8be9f80 | 1360 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
1361 | } else if ( | |
1362 | options.cipher == SSH_CIPHER_ARCFOUR || | |
6ae2364d | 1363 | options.cipher == SSH_CIPHER_3DES_CBC || |
1364 | options.cipher == SSH_CIPHER_CAST128_CBC || | |
1365 | options.cipher == SSH_CIPHER_BLOWFISH_CBC) { | |
a8be9f80 | 1366 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
8ce64345 | 1367 | myproposal[PROPOSAL_ENC_ALGS_STOC] = cipher_name(options.cipher); |
1368 | } | |
1369 | if (options.compression) { | |
1370 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = "zlib"; | |
1371 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "zlib"; | |
1372 | } else { | |
1373 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = "none"; | |
1374 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
1375 | } | |
1376 | for (i = 0; i < PROPOSAL_MAX; i++) | |
1377 | cprop[i] = xstrdup(myproposal[i]); | |
1378 | ||
1379 | client_kexinit = kex_init(cprop); | |
1380 | packet_start(SSH2_MSG_KEXINIT); | |
1381 | packet_put_raw(buffer_ptr(client_kexinit), buffer_len(client_kexinit)); | |
1382 | packet_send(); | |
1383 | packet_write_wait(); | |
1384 | ||
1385 | debug("done"); | |
1386 | ||
1387 | packet_read_expect(&payload_len, SSH2_MSG_KEXINIT); | |
1388 | ||
1389 | /* save payload for session_id */ | |
1390 | server_kexinit = xmalloc(sizeof(*server_kexinit)); | |
1391 | buffer_init(server_kexinit); | |
1392 | ptr = packet_get_raw(&payload_len); | |
1393 | buffer_append(server_kexinit, ptr, payload_len); | |
1394 | ||
1395 | /* skip cookie */ | |
1396 | for (i = 0; i < 16; i++) | |
1397 | (void) packet_get_char(); | |
1398 | /* kex init proposal strings */ | |
1399 | for (i = 0; i < PROPOSAL_MAX; i++) { | |
1400 | sprop[i] = packet_get_string(NULL); | |
1401 | debug("got kexinit string: %s", sprop[i]); | |
1402 | } | |
1403 | i = (int) packet_get_char(); | |
1404 | debug("first kex follow == %d", i); | |
1405 | i = packet_get_int(); | |
1406 | debug("reserved == %d", i); | |
6ae2364d | 1407 | packet_done(); |
8ce64345 | 1408 | |
1409 | debug("done read kexinit"); | |
1410 | kex = kex_choose_conf(cprop, sprop, 0); | |
1411 | ||
1412 | /* KEXDH */ | |
1413 | ||
1414 | debug("Sending SSH2_MSG_KEXDH_INIT."); | |
1415 | ||
1416 | /* generate and send 'e', client DH public key */ | |
a8be9f80 | 1417 | dh = dh_new_group1(); |
8ce64345 | 1418 | packet_start(SSH2_MSG_KEXDH_INIT); |
1419 | packet_put_bignum2(dh->pub_key); | |
1420 | packet_send(); | |
1421 | packet_write_wait(); | |
1422 | ||
1423 | #ifdef DEBUG_KEXDH | |
1424 | fprintf(stderr, "\np= "); | |
1425 | bignum_print(dh->p); | |
1426 | fprintf(stderr, "\ng= "); | |
1427 | bignum_print(dh->g); | |
1428 | fprintf(stderr, "\npub= "); | |
1429 | bignum_print(dh->pub_key); | |
1430 | fprintf(stderr, "\n"); | |
6ae2364d | 1431 | DHparams_print_fp(stderr, dh); |
8ce64345 | 1432 | #endif |
1433 | ||
1434 | debug("Wait SSH2_MSG_KEXDH_REPLY."); | |
1435 | ||
1436 | packet_read_expect(&payload_len, SSH2_MSG_KEXDH_REPLY); | |
1437 | ||
1438 | debug("Got SSH2_MSG_KEXDH_REPLY."); | |
1439 | ||
1440 | /* key, cert */ | |
1441 | server_host_key_blob = packet_get_string(&sbloblen); | |
1442 | server_host_key = dsa_serverkey_from_blob(server_host_key_blob, sbloblen); | |
1443 | if (server_host_key == NULL) | |
1444 | fatal("cannot decode server_host_key_blob"); | |
1445 | ||
1446 | check_host_key(host, hostaddr, server_host_key); | |
1447 | ||
1448 | /* DH paramter f, server public DH key */ | |
1449 | dh_server_pub = BN_new(); | |
1450 | if (dh_server_pub == NULL) | |
1451 | fatal("dh_server_pub == NULL"); | |
1452 | packet_get_bignum2(dh_server_pub, &dlen); | |
1453 | ||
1454 | #ifdef DEBUG_KEXDH | |
1455 | fprintf(stderr, "\ndh_server_pub= "); | |
1456 | bignum_print(dh_server_pub); | |
1457 | fprintf(stderr, "\n"); | |
1458 | debug("bits %d", BN_num_bits(dh_server_pub)); | |
1459 | #endif | |
1460 | ||
1461 | /* signed H */ | |
1462 | signature = packet_get_string(&slen); | |
6ae2364d | 1463 | packet_done(); |
8ce64345 | 1464 | |
a8be9f80 | 1465 | if (!dh_pub_is_valid(dh, dh_server_pub)) |
1466 | packet_disconnect("bad server public DH value"); | |
1467 | ||
8ce64345 | 1468 | klen = DH_size(dh); |
1469 | kbuf = xmalloc(klen); | |
1470 | kout = DH_compute_key(kbuf, dh_server_pub, dh); | |
1471 | #ifdef DEBUG_KEXDH | |
1472 | debug("shared secret: len %d/%d", klen, kout); | |
6ae2364d | 1473 | fprintf(stderr, "shared secret == "); |
1474 | for (i = 0; i< kout; i++) | |
1475 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
1476 | fprintf(stderr, "\n"); | |
8ce64345 | 1477 | #endif |
6ae2364d | 1478 | shared_secret = BN_new(); |
8ce64345 | 1479 | |
6ae2364d | 1480 | BN_bin2bn(kbuf, kout, shared_secret); |
8ce64345 | 1481 | memset(kbuf, 0, klen); |
1482 | xfree(kbuf); | |
1483 | ||
1484 | /* calc and verify H */ | |
1485 | hash = kex_hash( | |
1486 | client_version_string, | |
1487 | server_version_string, | |
1488 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
1489 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
1490 | server_host_key_blob, sbloblen, | |
1491 | dh->pub_key, | |
1492 | dh_server_pub, | |
1493 | shared_secret | |
1494 | ); | |
1495 | buffer_free(client_kexinit); | |
1496 | buffer_free(server_kexinit); | |
1497 | xfree(client_kexinit); | |
1498 | xfree(server_kexinit); | |
1499 | #ifdef DEBUG_KEXDH | |
6ae2364d | 1500 | fprintf(stderr, "hash == "); |
1501 | for (i = 0; i< 20; i++) | |
1502 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
1503 | fprintf(stderr, "\n"); | |
8ce64345 | 1504 | #endif |
1505 | dsa_verify(server_host_key, (unsigned char *)signature, slen, hash, 20); | |
1506 | key_free(server_host_key); | |
1507 | ||
1508 | kex_derive_keys(kex, hash, shared_secret); | |
1509 | packet_set_kex(kex); | |
1510 | ||
1511 | /* have keys, free DH */ | |
1512 | DH_free(dh); | |
1513 | ||
1514 | debug("Wait SSH2_MSG_NEWKEYS."); | |
1515 | packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS); | |
6ae2364d | 1516 | packet_done(); |
8ce64345 | 1517 | debug("GOT SSH2_MSG_NEWKEYS."); |
1518 | ||
1519 | debug("send SSH2_MSG_NEWKEYS."); | |
1520 | packet_start(SSH2_MSG_NEWKEYS); | |
1521 | packet_send(); | |
1522 | packet_write_wait(); | |
1523 | debug("done: send SSH2_MSG_NEWKEYS."); | |
1524 | ||
a8be9f80 | 1525 | #ifdef DEBUG_KEXDH |
8ce64345 | 1526 | /* send 1st encrypted/maced/compressed message */ |
1527 | packet_start(SSH2_MSG_IGNORE); | |
1528 | packet_put_cstring("markus"); | |
1529 | packet_send(); | |
1530 | packet_write_wait(); | |
a8be9f80 | 1531 | #endif |
8ce64345 | 1532 | debug("done: KEX2."); |
1533 | } | |
1534 | /* | |
1535 | * Authenticate user | |
1536 | */ | |
1537 | void | |
1538 | ssh_userauth2(int host_key_valid, RSA *own_host_key, | |
1539 | uid_t original_real_uid, char *host) | |
1540 | { | |
1541 | int type; | |
1542 | int plen; | |
1543 | unsigned int dlen; | |
1544 | int partial; | |
1545 | struct passwd *pw; | |
a8be9f80 | 1546 | char prompt[80]; |
8ce64345 | 1547 | char *server_user, *local_user; |
1548 | char *auths; | |
1549 | char *password; | |
6ae2364d | 1550 | char *service = "ssh-connection"; /* service name */ |
8ce64345 | 1551 | |
1552 | debug("send SSH2_MSG_SERVICE_REQUEST"); | |
1553 | packet_start(SSH2_MSG_SERVICE_REQUEST); | |
1554 | packet_put_cstring("ssh-userauth"); | |
1555 | packet_send(); | |
1556 | packet_write_wait(); | |
1557 | ||
1558 | type = packet_read(&plen); | |
1559 | if (type != SSH2_MSG_SERVICE_ACCEPT) { | |
1560 | fatal("denied SSH2_MSG_SERVICE_ACCEPT: %d", type); | |
1561 | } | |
6ae2364d | 1562 | if (packet_remaining() > 0) { |
1563 | char *reply = packet_get_string(&plen); | |
1564 | debug("service_accept: %s", reply); | |
1565 | xfree(reply); | |
1566 | } else { | |
1567 | /* payload empty for ssh-2.0.13 ?? */ | |
1568 | log("buggy server: service_accept w/o service"); | |
1569 | } | |
1570 | packet_done(); | |
8ce64345 | 1571 | debug("got SSH2_MSG_SERVICE_ACCEPT"); |
1572 | ||
1573 | /*XX COMMONCODE: */ | |
1574 | /* Get local user name. Use it as server user if no user name was given. */ | |
1575 | pw = getpwuid(original_real_uid); | |
1576 | if (!pw) | |
1577 | fatal("User id %d not found from user database.", original_real_uid); | |
1578 | local_user = xstrdup(pw->pw_name); | |
1579 | server_user = options.user ? options.user : local_user; | |
1580 | ||
1581 | /* INITIAL request for auth */ | |
1582 | packet_start(SSH2_MSG_USERAUTH_REQUEST); | |
1583 | packet_put_cstring(server_user); | |
1584 | packet_put_cstring(service); | |
1585 | packet_put_cstring("none"); | |
1586 | packet_send(); | |
1587 | packet_write_wait(); | |
1588 | ||
1589 | for (;;) { | |
1590 | type = packet_read(&plen); | |
1591 | if (type == SSH2_MSG_USERAUTH_SUCCESS) | |
1592 | break; | |
1593 | if (type != SSH2_MSG_USERAUTH_FAILURE) | |
1594 | fatal("access denied: %d", type); | |
1595 | /* SSH2_MSG_USERAUTH_FAILURE means: try again */ | |
1596 | auths = packet_get_string(&dlen); | |
1597 | debug("authentications that can continue: %s", auths); | |
1598 | partial = packet_get_char(); | |
6ae2364d | 1599 | packet_done(); |
8ce64345 | 1600 | if (partial) |
1601 | debug("partial success"); | |
1602 | if (strstr(auths, "password") == NULL) | |
1603 | fatal("passwd auth not supported: %s", auths); | |
1604 | xfree(auths); | |
1605 | /* try passwd */ | |
a8be9f80 | 1606 | snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ", |
1607 | server_user, host); | |
1608 | password = read_passphrase(prompt, 0); | |
8ce64345 | 1609 | packet_start(SSH2_MSG_USERAUTH_REQUEST); |
1610 | packet_put_cstring(server_user); | |
1611 | packet_put_cstring(service); | |
1612 | packet_put_cstring("password"); | |
1613 | packet_put_char(0); | |
1614 | packet_put_cstring(password); | |
1615 | memset(password, 0, strlen(password)); | |
1616 | xfree(password); | |
1617 | packet_send(); | |
1618 | packet_write_wait(); | |
1619 | } | |
6ae2364d | 1620 | packet_done(); |
8ce64345 | 1621 | debug("ssh-userauth2 successfull"); |
1622 | } | |
1623 | ||
95f1eccc | 1624 | /* |
7b2ea3a1 | 1625 | * SSH1 key exchange |
95f1eccc | 1626 | */ |
1627 | void | |
7b2ea3a1 | 1628 | ssh_kex(char *host, struct sockaddr *hostaddr) |
95f1eccc | 1629 | { |
7b2ea3a1 | 1630 | int i; |
95f1eccc | 1631 | BIGNUM *key; |
1632 | RSA *host_key; | |
1633 | RSA *public_key; | |
1634 | int bits, rbits; | |
8ce64345 | 1635 | int ssh_cipher_default = SSH_CIPHER_3DES; |
95f1eccc | 1636 | unsigned char session_key[SSH_SESSION_KEY_LENGTH]; |
7b2ea3a1 | 1637 | unsigned char cookie[8]; |
1638 | unsigned int supported_ciphers; | |
95f1eccc | 1639 | unsigned int server_flags, client_flags; |
1640 | int payload_len, clen, sum_len = 0; | |
1641 | u_int32_t rand = 0; | |
1642 | ||
95f1eccc | 1643 | debug("Waiting for server public key."); |
1644 | ||
1645 | /* Wait for a public key packet from the server. */ | |
1646 | packet_read_expect(&payload_len, SSH_SMSG_PUBLIC_KEY); | |
1647 | ||
7b2ea3a1 | 1648 | /* Get cookie from the packet. */ |
95f1eccc | 1649 | for (i = 0; i < 8; i++) |
7b2ea3a1 | 1650 | cookie[i] = packet_get_char(); |
95f1eccc | 1651 | |
1652 | /* Get the public key. */ | |
1653 | public_key = RSA_new(); | |
1654 | bits = packet_get_int();/* bits */ | |
1655 | public_key->e = BN_new(); | |
1656 | packet_get_bignum(public_key->e, &clen); | |
1657 | sum_len += clen; | |
1658 | public_key->n = BN_new(); | |
1659 | packet_get_bignum(public_key->n, &clen); | |
1660 | sum_len += clen; | |
1661 | ||
1662 | rbits = BN_num_bits(public_key->n); | |
1663 | if (bits != rbits) { | |
1664 | log("Warning: Server lies about size of server public key: " | |
1665 | "actual size is %d bits vs. announced %d.", rbits, bits); | |
1666 | log("Warning: This may be due to an old implementation of ssh."); | |
1667 | } | |
1668 | /* Get the host key. */ | |
1669 | host_key = RSA_new(); | |
1670 | bits = packet_get_int();/* bits */ | |
1671 | host_key->e = BN_new(); | |
1672 | packet_get_bignum(host_key->e, &clen); | |
1673 | sum_len += clen; | |
1674 | host_key->n = BN_new(); | |
1675 | packet_get_bignum(host_key->n, &clen); | |
1676 | sum_len += clen; | |
1677 | ||
1678 | rbits = BN_num_bits(host_key->n); | |
1679 | if (bits != rbits) { | |
1680 | log("Warning: Server lies about size of server host key: " | |
1681 | "actual size is %d bits vs. announced %d.", rbits, bits); | |
1682 | log("Warning: This may be due to an old implementation of ssh."); | |
1683 | } | |
1684 | ||
1685 | /* Get protocol flags. */ | |
1686 | server_flags = packet_get_int(); | |
1687 | packet_set_protocol_flags(server_flags); | |
1688 | ||
1689 | supported_ciphers = packet_get_int(); | |
1690 | supported_authentications = packet_get_int(); | |
1691 | ||
1692 | debug("Received server public key (%d bits) and host key (%d bits).", | |
1693 | BN_num_bits(public_key->n), BN_num_bits(host_key->n)); | |
1694 | ||
1695 | packet_integrity_check(payload_len, | |
1696 | 8 + 4 + sum_len + 0 + 4 + 0 + 0 + 4 + 4 + 4, | |
1697 | SSH_SMSG_PUBLIC_KEY); | |
1698 | ||
4fe2af09 | 1699 | check_rsa_host_key(host, hostaddr, host_key); |
95f1eccc | 1700 | |
1701 | client_flags = SSH_PROTOFLAG_SCREEN_NUMBER | SSH_PROTOFLAG_HOST_IN_FWD_OPEN; | |
1702 | ||
7b2ea3a1 | 1703 | compute_session_id(session_id, cookie, host_key->n, public_key->n); |
5260325f | 1704 | |
1705 | /* Generate a session key. */ | |
1706 | arc4random_stir(); | |
1707 | ||
aa3378df | 1708 | /* |
1709 | * Generate an encryption key for the session. The key is a 256 bit | |
1710 | * random number, interpreted as a 32-byte key, with the least | |
1711 | * significant 8 bits being the first byte of the key. | |
1712 | */ | |
5260325f | 1713 | for (i = 0; i < 32; i++) { |
1714 | if (i % 4 == 0) | |
1715 | rand = arc4random(); | |
1716 | session_key[i] = rand & 0xff; | |
1717 | rand >>= 8; | |
1718 | } | |
1719 | ||
aa3378df | 1720 | /* |
1721 | * According to the protocol spec, the first byte of the session key | |
1722 | * is the highest byte of the integer. The session key is xored with | |
1723 | * the first 16 bytes of the session id. | |
1724 | */ | |
5260325f | 1725 | key = BN_new(); |
1726 | BN_set_word(key, 0); | |
1727 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
1728 | BN_lshift(key, key, 8); | |
1729 | if (i < 16) | |
1730 | BN_add_word(key, session_key[i] ^ session_id[i]); | |
1731 | else | |
1732 | BN_add_word(key, session_key[i]); | |
1733 | } | |
1734 | ||
aa3378df | 1735 | /* |
1736 | * Encrypt the integer using the public key and host key of the | |
1737 | * server (key with smaller modulus first). | |
1738 | */ | |
5260325f | 1739 | if (BN_cmp(public_key->n, host_key->n) < 0) { |
1740 | /* Public key has smaller modulus. */ | |
1741 | if (BN_num_bits(host_key->n) < | |
1742 | BN_num_bits(public_key->n) + SSH_KEY_BITS_RESERVED) { | |
1743 | fatal("respond_to_rsa_challenge: host_key %d < public_key %d + " | |
1744 | "SSH_KEY_BITS_RESERVED %d", | |
1745 | BN_num_bits(host_key->n), | |
1746 | BN_num_bits(public_key->n), | |
1747 | SSH_KEY_BITS_RESERVED); | |
1748 | } | |
1749 | rsa_public_encrypt(key, key, public_key); | |
1750 | rsa_public_encrypt(key, key, host_key); | |
1751 | } else { | |
1752 | /* Host key has smaller modulus (or they are equal). */ | |
1753 | if (BN_num_bits(public_key->n) < | |
1754 | BN_num_bits(host_key->n) + SSH_KEY_BITS_RESERVED) { | |
1755 | fatal("respond_to_rsa_challenge: public_key %d < host_key %d + " | |
1756 | "SSH_KEY_BITS_RESERVED %d", | |
1757 | BN_num_bits(public_key->n), | |
1758 | BN_num_bits(host_key->n), | |
1759 | SSH_KEY_BITS_RESERVED); | |
1760 | } | |
1761 | rsa_public_encrypt(key, key, host_key); | |
1762 | rsa_public_encrypt(key, key, public_key); | |
1763 | } | |
1764 | ||
7b2ea3a1 | 1765 | /* Destroy the public keys since we no longer need them. */ |
1766 | RSA_free(public_key); | |
1767 | RSA_free(host_key); | |
1768 | ||
5260325f | 1769 | if (options.cipher == SSH_CIPHER_NOT_SET) { |
8ce64345 | 1770 | if (cipher_mask1() & supported_ciphers & (1 << ssh_cipher_default)) |
5260325f | 1771 | options.cipher = ssh_cipher_default; |
1772 | else { | |
1773 | debug("Cipher %s not supported, using %.100s instead.", | |
1774 | cipher_name(ssh_cipher_default), | |
1775 | cipher_name(SSH_FALLBACK_CIPHER)); | |
1776 | options.cipher = SSH_FALLBACK_CIPHER; | |
1777 | } | |
1778 | } | |
1779 | /* Check that the selected cipher is supported. */ | |
1780 | if (!(supported_ciphers & (1 << options.cipher))) | |
1781 | fatal("Selected cipher type %.100s not supported by server.", | |
1782 | cipher_name(options.cipher)); | |
1783 | ||
1784 | debug("Encryption type: %.100s", cipher_name(options.cipher)); | |
1785 | ||
1786 | /* Send the encrypted session key to the server. */ | |
1787 | packet_start(SSH_CMSG_SESSION_KEY); | |
1788 | packet_put_char(options.cipher); | |
1789 | ||
7b2ea3a1 | 1790 | /* Send the cookie back to the server. */ |
5260325f | 1791 | for (i = 0; i < 8; i++) |
7b2ea3a1 | 1792 | packet_put_char(cookie[i]); |
5260325f | 1793 | |
7b2ea3a1 | 1794 | /* Send and destroy the encrypted encryption key integer. */ |
5260325f | 1795 | packet_put_bignum(key); |
7b2ea3a1 | 1796 | BN_clear_free(key); |
5260325f | 1797 | |
1798 | /* Send protocol flags. */ | |
95f1eccc | 1799 | packet_put_int(client_flags); |
5260325f | 1800 | |
1801 | /* Send the packet now. */ | |
8efc0c15 | 1802 | packet_send(); |
1803 | packet_write_wait(); | |
5260325f | 1804 | |
5260325f | 1805 | debug("Sent encrypted session key."); |
1806 | ||
1807 | /* Set the encryption key. */ | |
1808 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, options.cipher); | |
1809 | ||
1810 | /* We will no longer need the session key here. Destroy any extra copies. */ | |
1811 | memset(session_key, 0, sizeof(session_key)); | |
1812 | ||
aa3378df | 1813 | /* |
1814 | * Expect a success message from the server. Note that this message | |
1815 | * will be received in encrypted form. | |
1816 | */ | |
5260325f | 1817 | packet_read_expect(&payload_len, SSH_SMSG_SUCCESS); |
1818 | ||
1819 | debug("Received encrypted confirmation."); | |
7b2ea3a1 | 1820 | } |
1821 | ||
1822 | /* | |
1823 | * Authenticate user | |
1824 | */ | |
1825 | void | |
1826 | ssh_userauth(int host_key_valid, RSA *own_host_key, | |
1827 | uid_t original_real_uid, char *host) | |
1828 | { | |
1829 | int i, type; | |
1830 | int payload_len; | |
1831 | struct passwd *pw; | |
1832 | const char *server_user, *local_user; | |
1833 | ||
1834 | /* Get local user name. Use it as server user if no user name was given. */ | |
1835 | pw = getpwuid(original_real_uid); | |
1836 | if (!pw) | |
1837 | fatal("User id %d not found from user database.", original_real_uid); | |
1838 | local_user = xstrdup(pw->pw_name); | |
1839 | server_user = options.user ? options.user : local_user; | |
5260325f | 1840 | |
1841 | /* Send the name of the user to log in as on the server. */ | |
1842 | packet_start(SSH_CMSG_USER); | |
1843 | packet_put_string(server_user, strlen(server_user)); | |
1844 | packet_send(); | |
1845 | packet_write_wait(); | |
1846 | ||
aa3378df | 1847 | /* |
1848 | * The server should respond with success if no authentication is | |
1849 | * needed (the user has no password). Otherwise the server responds | |
1850 | * with failure. | |
1851 | */ | |
8efc0c15 | 1852 | type = packet_read(&payload_len); |
5260325f | 1853 | |
1854 | /* check whether the connection was accepted without authentication. */ | |
8efc0c15 | 1855 | if (type == SSH_SMSG_SUCCESS) |
5260325f | 1856 | return; |
8efc0c15 | 1857 | if (type != SSH_SMSG_FAILURE) |
5260325f | 1858 | packet_disconnect("Protocol error: got %d in response to SSH_CMSG_USER", |
1859 | type); | |
1860 | ||
1861 | #ifdef AFS | |
1862 | /* Try Kerberos tgt passing if the server supports it. */ | |
1863 | if ((supported_authentications & (1 << SSH_PASS_KERBEROS_TGT)) && | |
1864 | options.kerberos_tgt_passing) { | |
1865 | if (options.cipher == SSH_CIPHER_NONE) | |
1866 | log("WARNING: Encryption is disabled! Ticket will be transmitted in the clear!"); | |
1867 | (void) send_kerberos_tgt(); | |
1868 | } | |
1869 | /* Try AFS token passing if the server supports it. */ | |
1870 | if ((supported_authentications & (1 << SSH_PASS_AFS_TOKEN)) && | |
1871 | options.afs_token_passing && k_hasafs()) { | |
1872 | if (options.cipher == SSH_CIPHER_NONE) | |
1873 | log("WARNING: Encryption is disabled! Token will be transmitted in the clear!"); | |
1874 | send_afs_tokens(); | |
1875 | } | |
1876 | #endif /* AFS */ | |
8efc0c15 | 1877 | |
5260325f | 1878 | #ifdef KRB4 |
1879 | if ((supported_authentications & (1 << SSH_AUTH_KERBEROS)) && | |
1880 | options.kerberos_authentication) { | |
1881 | debug("Trying Kerberos authentication."); | |
1882 | if (try_kerberos_authentication()) { | |
1883 | /* The server should respond with success or failure. */ | |
1884 | type = packet_read(&payload_len); | |
1885 | if (type == SSH_SMSG_SUCCESS) | |
1886 | return; | |
1887 | if (type != SSH_SMSG_FAILURE) | |
1888 | packet_disconnect("Protocol error: got %d in response to Kerberos auth", type); | |
1889 | } | |
1890 | } | |
1891 | #endif /* KRB4 */ | |
1892 | ||
aa3378df | 1893 | /* |
1894 | * Use rhosts authentication if running in privileged socket and we | |
1895 | * do not wish to remain anonymous. | |
1896 | */ | |
5260325f | 1897 | if ((supported_authentications & (1 << SSH_AUTH_RHOSTS)) && |
1898 | options.rhosts_authentication) { | |
1899 | debug("Trying rhosts authentication."); | |
1900 | packet_start(SSH_CMSG_AUTH_RHOSTS); | |
1901 | packet_put_string(local_user, strlen(local_user)); | |
1902 | packet_send(); | |
1903 | packet_write_wait(); | |
1904 | ||
1905 | /* The server should respond with success or failure. */ | |
1906 | type = packet_read(&payload_len); | |
1907 | if (type == SSH_SMSG_SUCCESS) | |
1908 | return; | |
1909 | if (type != SSH_SMSG_FAILURE) | |
1910 | packet_disconnect("Protocol error: got %d in response to rhosts auth", | |
1911 | type); | |
1912 | } | |
aa3378df | 1913 | /* |
1914 | * Try .rhosts or /etc/hosts.equiv authentication with RSA host | |
1915 | * authentication. | |
1916 | */ | |
5260325f | 1917 | if ((supported_authentications & (1 << SSH_AUTH_RHOSTS_RSA)) && |
1918 | options.rhosts_rsa_authentication && host_key_valid) { | |
1919 | if (try_rhosts_rsa_authentication(local_user, own_host_key)) | |
1920 | return; | |
1921 | } | |
1922 | /* Try RSA authentication if the server supports it. */ | |
1923 | if ((supported_authentications & (1 << SSH_AUTH_RSA)) && | |
1924 | options.rsa_authentication) { | |
aa3378df | 1925 | /* |
1926 | * Try RSA authentication using the authentication agent. The | |
1927 | * agent is tried first because no passphrase is needed for | |
1928 | * it, whereas identity files may require passphrases. | |
1929 | */ | |
5260325f | 1930 | if (try_agent_authentication()) |
1931 | return; | |
1932 | ||
1933 | /* Try RSA authentication for each identity. */ | |
1934 | for (i = 0; i < options.num_identity_files; i++) | |
57112b5a | 1935 | if (try_rsa_authentication(options.identity_files[i])) |
5260325f | 1936 | return; |
1937 | } | |
1938 | /* Try skey authentication if the server supports it. */ | |
1939 | if ((supported_authentications & (1 << SSH_AUTH_TIS)) && | |
1940 | options.skey_authentication && !options.batch_mode) { | |
57112b5a | 1941 | if (try_skey_authentication()) |
1942 | return; | |
5260325f | 1943 | } |
1944 | /* Try password authentication if the server supports it. */ | |
1945 | if ((supported_authentications & (1 << SSH_AUTH_PASSWORD)) && | |
1946 | options.password_authentication && !options.batch_mode) { | |
1947 | char prompt[80]; | |
a408af76 | 1948 | |
57112b5a | 1949 | snprintf(prompt, sizeof(prompt), "%.30s@%.40s's password: ", |
a408af76 | 1950 | server_user, host); |
57112b5a | 1951 | if (try_password_authentication(prompt)) |
1952 | return; | |
5260325f | 1953 | } |
1954 | /* All authentication methods have failed. Exit with an error message. */ | |
1955 | fatal("Permission denied."); | |
1956 | /* NOTREACHED */ | |
8efc0c15 | 1957 | } |
7b2ea3a1 | 1958 | /* |
1959 | * Starts a dialog with the server, and authenticates the current user on the | |
1960 | * server. This does not need any extra privileges. The basic connection | |
1961 | * to the server must already have been established before this is called. | |
1962 | * If login fails, this function prints an error and never returns. | |
1963 | * This function does not require super-user privileges. | |
1964 | */ | |
1965 | void | |
1966 | ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost, | |
1967 | struct sockaddr *hostaddr, uid_t original_real_uid) | |
1968 | { | |
1969 | char *host, *cp; | |
1970 | ||
1971 | /* Convert the user-supplied hostname into all lowercase. */ | |
1972 | host = xstrdup(orighost); | |
1973 | for (cp = host; *cp; cp++) | |
1974 | if (isupper(*cp)) | |
1975 | *cp = tolower(*cp); | |
1976 | ||
1977 | /* Exchange protocol version identification strings with the server. */ | |
1978 | ssh_exchange_identification(); | |
1979 | ||
1980 | /* Put the connection into non-blocking mode. */ | |
1981 | packet_set_nonblocking(); | |
1982 | ||
7b2ea3a1 | 1983 | /* key exchange */ |
7b2ea3a1 | 1984 | /* authenticate user */ |
8ce64345 | 1985 | if (compat20) { |
1986 | ssh_kex2(host, hostaddr); | |
1987 | ssh_userauth2(host_key_valid, own_host_key, original_real_uid, host); | |
1988 | } else { | |
1989 | supported_authentications = 0; | |
1990 | ssh_kex(host, hostaddr); | |
1991 | if (supported_authentications == 0) | |
1992 | fatal("supported_authentications == 0."); | |
1993 | ssh_userauth(host_key_valid, own_host_key, original_real_uid, host); | |
1994 | } | |
7b2ea3a1 | 1995 | } |