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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: Fri Mar 17 17:09:28 1995 ylo | |
6 | * This program is the ssh daemon. It listens for connections from clients, and | |
7 | * performs authentication, executes use commands or shell, and forwards | |
8 | * information to/from the application to the user client over an encrypted | |
9 | * connection. This can also handle forwarding of X11, TCP/IP, and authentication | |
10 | * agent connections. | |
e78a59f5 | 11 | * |
12 | * SSH2 implementation, | |
13 | * Copyright (c) 2000 Markus Friedl. All rights reserved. | |
5260325f | 14 | */ |
8efc0c15 | 15 | |
16 | #include "includes.h" | |
f54651ce | 17 | RCSID("$OpenBSD: sshd.c,v 1.104 2000/04/12 09:39:10 markus Exp $"); |
8efc0c15 | 18 | |
19 | #include "xmalloc.h" | |
20 | #include "rsa.h" | |
21 | #include "ssh.h" | |
22 | #include "pty.h" | |
23 | #include "packet.h" | |
8efc0c15 | 24 | #include "cipher.h" |
25 | #include "mpaux.h" | |
26 | #include "servconf.h" | |
27 | #include "uidswap.h" | |
28 | #include "compat.h" | |
7368a6c8 | 29 | #include "buffer.h" |
30 | ||
e78a59f5 | 31 | #include "ssh2.h" |
7368a6c8 | 32 | #ifdef HAVE_OPENSSL |
33 | # include <openssl/dh.h> | |
34 | # include <openssl/bn.h> | |
35 | # include <openssl/hmac.h> | |
36 | # include <openssl/dsa.h> | |
37 | # include <openssl/rsa.h> | |
38 | #endif | |
39 | #ifdef HAVE_SSL | |
40 | # include <ssl/dh.h> | |
41 | # include <ssl/bn.h> | |
42 | # include <ssl/hmac.h> | |
43 | # include <ssl/dsa.h> | |
44 | # include <ssl/rsa.h> | |
45 | #endif | |
e78a59f5 | 46 | #include "kex.h" |
7368a6c8 | 47 | #include "key.h" |
e78a59f5 | 48 | #include "dsa.h" |
7368a6c8 | 49 | |
50 | #include "auth.h" | |
e78a59f5 | 51 | #include "myproposal.h" |
8efc0c15 | 52 | |
53 | #ifdef LIBWRAP | |
54 | #include <tcpd.h> | |
55 | #include <syslog.h> | |
56 | int allow_severity = LOG_INFO; | |
57 | int deny_severity = LOG_WARNING; | |
58 | #endif /* LIBWRAP */ | |
59 | ||
60 | #ifndef O_NOCTTY | |
61 | #define O_NOCTTY 0 | |
62 | #endif | |
63 | ||
8efc0c15 | 64 | /* Server configuration options. */ |
65 | ServerOptions options; | |
66 | ||
67 | /* Name of the server configuration file. */ | |
68 | char *config_file_name = SERVER_CONFIG_FILE; | |
69 | ||
48e671d5 | 70 | /* |
71 | * Flag indicating whether IPv4 or IPv6. This can be set on the command line. | |
72 | * Default value is AF_UNSPEC means both IPv4 and IPv6. | |
73 | */ | |
59e76f33 | 74 | #ifdef IPV4_DEFAULT |
75 | int IPv4or6 = AF_INET; | |
76 | #else | |
48e671d5 | 77 | int IPv4or6 = AF_UNSPEC; |
59e76f33 | 78 | #endif |
48e671d5 | 79 | |
5260325f | 80 | /* |
81 | * Debug mode flag. This can be set on the command line. If debug | |
82 | * mode is enabled, extra debugging output will be sent to the system | |
83 | * log, the daemon will not go to background, and will exit after processing | |
84 | * the first connection. | |
85 | */ | |
8efc0c15 | 86 | int debug_flag = 0; |
87 | ||
88 | /* Flag indicating that the daemon is being started from inetd. */ | |
89 | int inetd_flag = 0; | |
90 | ||
6a17f9c2 | 91 | /* debug goes to stderr unless inetd_flag is set */ |
92 | int log_stderr = 0; | |
93 | ||
8efc0c15 | 94 | /* argv[0] without path. */ |
95 | char *av0; | |
96 | ||
97 | /* Saved arguments to main(). */ | |
98 | char **saved_argv; | |
99 | ||
aa3378df | 100 | /* |
48e671d5 | 101 | * The sockets that the server is listening; this is used in the SIGHUP |
102 | * signal handler. | |
aa3378df | 103 | */ |
48e671d5 | 104 | #define MAX_LISTEN_SOCKS 16 |
105 | int listen_socks[MAX_LISTEN_SOCKS]; | |
106 | int num_listen_socks = 0; | |
8efc0c15 | 107 | |
aa3378df | 108 | /* |
109 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
110 | * sshd will skip the version-number exchange | |
111 | */ | |
5260325f | 112 | char *client_version_string = NULL; |
7368a6c8 | 113 | char *server_version_string = NULL; |
8efc0c15 | 114 | |
aa3378df | 115 | /* |
116 | * Any really sensitive data in the application is contained in this | |
117 | * structure. The idea is that this structure could be locked into memory so | |
118 | * that the pages do not get written into swap. However, there are some | |
119 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
120 | * have access to the internals of them, and locking just the structure is | |
121 | * not very useful. Currently, memory locking is not implemented. | |
122 | */ | |
5260325f | 123 | struct { |
124 | RSA *private_key; /* Private part of server key. */ | |
125 | RSA *host_key; /* Private part of host key. */ | |
8efc0c15 | 126 | } sensitive_data; |
127 | ||
aa3378df | 128 | /* |
129 | * Flag indicating whether the current session key has been used. This flag | |
130 | * is set whenever the key is used, and cleared when the key is regenerated. | |
131 | */ | |
8efc0c15 | 132 | int key_used = 0; |
133 | ||
134 | /* This is set to true when SIGHUP is received. */ | |
135 | int received_sighup = 0; | |
136 | ||
137 | /* Public side of the server key. This value is regenerated regularly with | |
138 | the private key. */ | |
139 | RSA *public_key; | |
140 | ||
7368a6c8 | 141 | /* session identifier, used by RSA-auth */ |
142 | unsigned char session_id[16]; | |
e7c0f9d5 | 143 | |
7368a6c8 | 144 | /* Prototypes for various functions defined later in this file. */ |
145 | void do_ssh1_kex(); | |
e78a59f5 | 146 | void do_ssh2_kex(); |
c8d54615 | 147 | |
48e671d5 | 148 | /* |
149 | * Close all listening sockets | |
150 | */ | |
151 | void | |
152 | close_listen_socks(void) | |
153 | { | |
154 | int i; | |
155 | for (i = 0; i < num_listen_socks; i++) | |
156 | close(listen_socks[i]); | |
157 | num_listen_socks = -1; | |
158 | } | |
159 | ||
5260325f | 160 | /* |
161 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
162 | * the effect is to reread the configuration file (and to regenerate | |
163 | * the server key). | |
164 | */ | |
165 | void | |
166 | sighup_handler(int sig) | |
8efc0c15 | 167 | { |
5260325f | 168 | received_sighup = 1; |
169 | signal(SIGHUP, sighup_handler); | |
8efc0c15 | 170 | } |
171 | ||
5260325f | 172 | /* |
173 | * Called from the main program after receiving SIGHUP. | |
174 | * Restarts the server. | |
175 | */ | |
176 | void | |
177 | sighup_restart() | |
8efc0c15 | 178 | { |
5260325f | 179 | log("Received SIGHUP; restarting."); |
48e671d5 | 180 | close_listen_socks(); |
5260325f | 181 | execv(saved_argv[0], saved_argv); |
182 | log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno)); | |
183 | exit(1); | |
8efc0c15 | 184 | } |
185 | ||
5260325f | 186 | /* |
187 | * Generic signal handler for terminating signals in the master daemon. | |
188 | * These close the listen socket; not closing it seems to cause "Address | |
189 | * already in use" problems on some machines, which is inconvenient. | |
190 | */ | |
191 | void | |
192 | sigterm_handler(int sig) | |
8efc0c15 | 193 | { |
5260325f | 194 | log("Received signal %d; terminating.", sig); |
48e671d5 | 195 | close_listen_socks(); |
5260325f | 196 | exit(255); |
8efc0c15 | 197 | } |
198 | ||
5260325f | 199 | /* |
200 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
201 | * reap any zombies left by exited c. | |
202 | */ | |
203 | void | |
204 | main_sigchld_handler(int sig) | |
8efc0c15 | 205 | { |
5260325f | 206 | int save_errno = errno; |
207 | int status; | |
5ad13cd7 | 208 | |
5260325f | 209 | while (waitpid(-1, &status, WNOHANG) > 0) |
210 | ; | |
5ad13cd7 | 211 | |
5260325f | 212 | signal(SIGCHLD, main_sigchld_handler); |
213 | errno = save_errno; | |
8efc0c15 | 214 | } |
215 | ||
5260325f | 216 | /* |
217 | * Signal handler for the alarm after the login grace period has expired. | |
218 | */ | |
219 | void | |
220 | grace_alarm_handler(int sig) | |
8efc0c15 | 221 | { |
5260325f | 222 | /* Close the connection. */ |
223 | packet_close(); | |
8efc0c15 | 224 | |
5260325f | 225 | /* Log error and exit. */ |
226 | fatal("Timeout before authentication for %s.", get_remote_ipaddr()); | |
227 | } | |
8efc0c15 | 228 | |
5260325f | 229 | /* |
230 | * Signal handler for the key regeneration alarm. Note that this | |
231 | * alarm only occurs in the daemon waiting for connections, and it does not | |
232 | * do anything with the private key or random state before forking. | |
233 | * Thus there should be no concurrency control/asynchronous execution | |
234 | * problems. | |
235 | */ | |
236 | void | |
237 | key_regeneration_alarm(int sig) | |
238 | { | |
239 | int save_errno = errno; | |
240 | ||
241 | /* Check if we should generate a new key. */ | |
242 | if (key_used) { | |
243 | /* This should really be done in the background. */ | |
244 | log("Generating new %d bit RSA key.", options.server_key_bits); | |
245 | ||
246 | if (sensitive_data.private_key != NULL) | |
247 | RSA_free(sensitive_data.private_key); | |
248 | sensitive_data.private_key = RSA_new(); | |
249 | ||
250 | if (public_key != NULL) | |
251 | RSA_free(public_key); | |
252 | public_key = RSA_new(); | |
253 | ||
254 | rsa_generate_key(sensitive_data.private_key, public_key, | |
255 | options.server_key_bits); | |
256 | arc4random_stir(); | |
257 | key_used = 0; | |
258 | log("RSA key generation complete."); | |
259 | } | |
260 | /* Reschedule the alarm. */ | |
261 | signal(SIGALRM, key_regeneration_alarm); | |
262 | alarm(options.key_regeneration_time); | |
263 | errno = save_errno; | |
264 | } | |
8efc0c15 | 265 | |
e78a59f5 | 266 | char * |
267 | chop(char *s) | |
268 | { | |
269 | char *t = s; | |
270 | while (*t) { | |
271 | if(*t == '\n' || *t == '\r') { | |
272 | *t = '\0'; | |
273 | return s; | |
274 | } | |
275 | t++; | |
276 | } | |
277 | return s; | |
278 | ||
279 | } | |
280 | ||
7368a6c8 | 281 | void |
282 | sshd_exchange_identification(int sock_in, int sock_out) | |
283 | { | |
a8be9f80 | 284 | int i, mismatch; |
7368a6c8 | 285 | int remote_major, remote_minor; |
a8be9f80 | 286 | int major, minor; |
7368a6c8 | 287 | char *s; |
288 | char buf[256]; /* Must not be larger than remote_version. */ | |
289 | char remote_version[256]; /* Must be at least as big as buf. */ | |
290 | ||
a8be9f80 | 291 | if ((options.protocol & SSH_PROTO_1) && |
292 | (options.protocol & SSH_PROTO_2)) { | |
293 | major = PROTOCOL_MAJOR_1; | |
294 | minor = 99; | |
295 | } else if (options.protocol & SSH_PROTO_2) { | |
296 | major = PROTOCOL_MAJOR_2; | |
297 | minor = PROTOCOL_MINOR_2; | |
298 | } else { | |
299 | major = PROTOCOL_MAJOR_1; | |
300 | minor = PROTOCOL_MINOR_1; | |
301 | } | |
302 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
7368a6c8 | 303 | server_version_string = xstrdup(buf); |
304 | ||
305 | if (client_version_string == NULL) { | |
306 | /* Send our protocol version identification. */ | |
307 | if (atomicio(write, sock_out, server_version_string, strlen(server_version_string)) | |
308 | != strlen(server_version_string)) { | |
309 | log("Could not write ident string to %s.", get_remote_ipaddr()); | |
310 | fatal_cleanup(); | |
311 | } | |
312 | ||
313 | /* Read other side\'s version identification. */ | |
314 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
315 | if (read(sock_in, &buf[i], 1) != 1) { | |
316 | log("Did not receive ident string from %s.", get_remote_ipaddr()); | |
317 | fatal_cleanup(); | |
318 | } | |
319 | if (buf[i] == '\r') { | |
320 | buf[i] = '\n'; | |
321 | buf[i + 1] = 0; | |
322 | continue; | |
7368a6c8 | 323 | } |
324 | if (buf[i] == '\n') { | |
325 | /* buf[i] == '\n' */ | |
326 | buf[i + 1] = 0; | |
327 | break; | |
328 | } | |
329 | } | |
330 | buf[sizeof(buf) - 1] = 0; | |
331 | client_version_string = xstrdup(buf); | |
332 | } | |
333 | ||
334 | /* | |
335 | * Check that the versions match. In future this might accept | |
336 | * several versions and set appropriate flags to handle them. | |
337 | */ | |
338 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
339 | &remote_major, &remote_minor, remote_version) != 3) { | |
340 | s = "Protocol mismatch.\n"; | |
341 | (void) atomicio(write, sock_out, s, strlen(s)); | |
342 | close(sock_in); | |
343 | close(sock_out); | |
344 | log("Bad protocol version identification '%.100s' from %s", | |
345 | client_version_string, get_remote_ipaddr()); | |
346 | fatal_cleanup(); | |
347 | } | |
348 | debug("Client protocol version %d.%d; client software version %.100s", | |
349 | remote_major, remote_minor, remote_version); | |
350 | ||
e78a59f5 | 351 | compat_datafellows(remote_version); |
352 | ||
a8be9f80 | 353 | mismatch = 0; |
7368a6c8 | 354 | switch(remote_major) { |
355 | case 1: | |
a8be9f80 | 356 | if (!(options.protocol & SSH_PROTO_1)) { |
357 | mismatch = 1; | |
358 | break; | |
359 | } | |
7368a6c8 | 360 | if (remote_minor < 3) { |
361 | packet_disconnect("Your ssh version is too old and" | |
362 | "is no longer supported. Please install a newer version."); | |
363 | } else if (remote_minor == 3) { | |
364 | /* note that this disables agent-forwarding */ | |
365 | enable_compat13(); | |
366 | } | |
a8be9f80 | 367 | if (remote_minor == 99) { |
368 | if (options.protocol & SSH_PROTO_2) | |
369 | enable_compat20(); | |
370 | else | |
371 | mismatch = 1; | |
372 | } | |
373 | break; | |
e78a59f5 | 374 | case 2: |
a8be9f80 | 375 | if (options.protocol & SSH_PROTO_2) { |
e78a59f5 | 376 | enable_compat20(); |
377 | break; | |
378 | } | |
379 | /* FALLTHROUGH */ | |
7368a6c8 | 380 | default: |
a8be9f80 | 381 | mismatch = 1; |
382 | break; | |
383 | } | |
384 | chop(server_version_string); | |
385 | chop(client_version_string); | |
386 | debug("Local version string %.200s", server_version_string); | |
387 | ||
388 | if (mismatch) { | |
7368a6c8 | 389 | s = "Protocol major versions differ.\n"; |
390 | (void) atomicio(write, sock_out, s, strlen(s)); | |
391 | close(sock_in); | |
392 | close(sock_out); | |
a8be9f80 | 393 | log("Protocol major versions differ for %s: %.200s vs. %.200s", |
394 | get_remote_ipaddr(), | |
395 | server_version_string, client_version_string); | |
7368a6c8 | 396 | fatal_cleanup(); |
7368a6c8 | 397 | } |
398 | } | |
399 | ||
5260325f | 400 | /* |
401 | * Main program for the daemon. | |
402 | */ | |
8efc0c15 | 403 | int |
404 | main(int ac, char **av) | |
405 | { | |
5260325f | 406 | extern char *optarg; |
407 | extern int optind; | |
48e671d5 | 408 | int opt, sock_in = 0, sock_out = 0, newsock, i, fdsetsz, pid, on = 1; |
409 | socklen_t fromlen; | |
5260325f | 410 | int silentrsa = 0; |
48e671d5 | 411 | fd_set *fdset; |
412 | struct sockaddr_storage from; | |
5260325f | 413 | const char *remote_ip; |
414 | int remote_port; | |
415 | char *comment; | |
416 | FILE *f; | |
417 | struct linger linger; | |
48e671d5 | 418 | struct addrinfo *ai; |
419 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
420 | int listen_sock, maxfd; | |
5260325f | 421 | |
422 | /* Save argv[0]. */ | |
423 | saved_argv = av; | |
424 | if (strchr(av[0], '/')) | |
425 | av0 = strrchr(av[0], '/') + 1; | |
426 | else | |
427 | av0 = av[0]; | |
428 | ||
429 | /* Initialize configuration options to their default values. */ | |
430 | initialize_server_options(&options); | |
431 | ||
432 | /* Parse command-line arguments. */ | |
a8be9f80 | 433 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:diqQ46")) != EOF) { |
5260325f | 434 | switch (opt) { |
48e671d5 | 435 | case '4': |
436 | IPv4or6 = AF_INET; | |
437 | break; | |
438 | case '6': | |
439 | IPv4or6 = AF_INET6; | |
440 | break; | |
5260325f | 441 | case 'f': |
442 | config_file_name = optarg; | |
443 | break; | |
444 | case 'd': | |
445 | debug_flag = 1; | |
446 | options.log_level = SYSLOG_LEVEL_DEBUG; | |
447 | break; | |
448 | case 'i': | |
449 | inetd_flag = 1; | |
450 | break; | |
451 | case 'Q': | |
452 | silentrsa = 1; | |
453 | break; | |
454 | case 'q': | |
455 | options.log_level = SYSLOG_LEVEL_QUIET; | |
456 | break; | |
457 | case 'b': | |
458 | options.server_key_bits = atoi(optarg); | |
459 | break; | |
460 | case 'p': | |
48e671d5 | 461 | options.ports_from_cmdline = 1; |
462 | if (options.num_ports >= MAX_PORTS) | |
463 | fatal("too many ports.\n"); | |
464 | options.ports[options.num_ports++] = atoi(optarg); | |
5260325f | 465 | break; |
466 | case 'g': | |
467 | options.login_grace_time = atoi(optarg); | |
468 | break; | |
469 | case 'k': | |
470 | options.key_regeneration_time = atoi(optarg); | |
471 | break; | |
472 | case 'h': | |
473 | options.host_key_file = optarg; | |
474 | break; | |
475 | case 'V': | |
476 | client_version_string = optarg; | |
477 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
478 | inetd_flag = 1; | |
479 | break; | |
480 | case '?': | |
481 | default: | |
482 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
483 | fprintf(stderr, "Usage: %s [options]\n", av0); | |
484 | fprintf(stderr, "Options:\n"); | |
aa3378df | 485 | fprintf(stderr, " -f file Configuration file (default %s)\n", SERVER_CONFIG_FILE); |
5260325f | 486 | fprintf(stderr, " -d Debugging mode\n"); |
487 | fprintf(stderr, " -i Started from inetd\n"); | |
488 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
489 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
490 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
491 | fprintf(stderr, " -g seconds Grace period for authentication (default: 300)\n"); | |
492 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
493 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
48e671d5 | 494 | HOST_KEY_FILE); |
495 | fprintf(stderr, " -4 Use IPv4 only\n"); | |
496 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
5260325f | 497 | exit(1); |
498 | } | |
499 | } | |
500 | ||
48e671d5 | 501 | /* |
502 | * Force logging to stderr until we have loaded the private host | |
503 | * key (unless started from inetd) | |
504 | */ | |
505 | log_init(av0, | |
506 | options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level, | |
507 | options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility, | |
508 | !inetd_flag); | |
509 | ||
5260325f | 510 | /* check if RSA support exists */ |
511 | if (rsa_alive() == 0) { | |
512 | if (silentrsa == 0) | |
513 | printf("sshd: no RSA support in libssl and libcrypto -- exiting. See ssl(8)\n"); | |
514 | log("no RSA support in libssl and libcrypto -- exiting. See ssl(8)"); | |
515 | exit(1); | |
516 | } | |
517 | /* Read server configuration options from the configuration file. */ | |
518 | read_server_config(&options, config_file_name); | |
519 | ||
520 | /* Fill in default values for those options not explicitly set. */ | |
521 | fill_default_server_options(&options); | |
522 | ||
523 | /* Check certain values for sanity. */ | |
524 | if (options.server_key_bits < 512 || | |
525 | options.server_key_bits > 32768) { | |
526 | fprintf(stderr, "Bad server key size.\n"); | |
527 | exit(1); | |
528 | } | |
5260325f | 529 | /* Check that there are no remaining arguments. */ |
530 | if (optind < ac) { | |
531 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
532 | exit(1); | |
8efc0c15 | 533 | } |
5260325f | 534 | |
535 | debug("sshd version %.100s", SSH_VERSION); | |
536 | ||
537 | sensitive_data.host_key = RSA_new(); | |
538 | errno = 0; | |
539 | /* Load the host key. It must have empty passphrase. */ | |
540 | if (!load_private_key(options.host_key_file, "", | |
541 | sensitive_data.host_key, &comment)) { | |
542 | error("Could not load host key: %.200s: %.100s", | |
543 | options.host_key_file, strerror(errno)); | |
544 | exit(1); | |
545 | } | |
546 | xfree(comment); | |
547 | ||
548 | /* Initialize the log (it is reinitialized below in case we | |
549 | forked). */ | |
550 | if (debug_flag && !inetd_flag) | |
551 | log_stderr = 1; | |
552 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
553 | ||
554 | /* If not in debugging mode, and not started from inetd, | |
555 | disconnect from the controlling terminal, and fork. The | |
556 | original process exits. */ | |
557 | if (!debug_flag && !inetd_flag) { | |
8efc0c15 | 558 | #ifdef TIOCNOTTY |
5260325f | 559 | int fd; |
8efc0c15 | 560 | #endif /* TIOCNOTTY */ |
5260325f | 561 | if (daemon(0, 0) < 0) |
562 | fatal("daemon() failed: %.200s", strerror(errno)); | |
563 | ||
564 | /* Disconnect from the controlling tty. */ | |
8efc0c15 | 565 | #ifdef TIOCNOTTY |
5260325f | 566 | fd = open("/dev/tty", O_RDWR | O_NOCTTY); |
567 | if (fd >= 0) { | |
568 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
569 | close(fd); | |
570 | } | |
8efc0c15 | 571 | #endif /* TIOCNOTTY */ |
8efc0c15 | 572 | } |
5260325f | 573 | /* Reinitialize the log (because of the fork above). */ |
574 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
575 | ||
576 | /* Check that server and host key lengths differ sufficiently. | |
577 | This is necessary to make double encryption work with rsaref. | |
578 | Oh, I hate software patents. I dont know if this can go? Niels */ | |
579 | if (options.server_key_bits > | |
580 | BN_num_bits(sensitive_data.host_key->n) - SSH_KEY_BITS_RESERVED && | |
581 | options.server_key_bits < | |
582 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) { | |
583 | options.server_key_bits = | |
584 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED; | |
585 | debug("Forcing server key to %d bits to make it differ from host key.", | |
586 | options.server_key_bits); | |
8efc0c15 | 587 | } |
5260325f | 588 | /* Do not display messages to stdout in RSA code. */ |
589 | rsa_set_verbose(0); | |
590 | ||
591 | /* Initialize the random number generator. */ | |
592 | arc4random_stir(); | |
593 | ||
594 | /* Chdir to the root directory so that the current disk can be | |
595 | unmounted if desired. */ | |
596 | chdir("/"); | |
597 | ||
5260325f | 598 | /* Start listening for a socket, unless started from inetd. */ |
599 | if (inetd_flag) { | |
600 | int s1, s2; | |
601 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ | |
602 | s2 = dup(s1); | |
603 | sock_in = dup(0); | |
604 | sock_out = dup(1); | |
605 | /* We intentionally do not close the descriptors 0, 1, and 2 | |
606 | as our code for setting the descriptors won\'t work | |
607 | if ttyfd happens to be one of those. */ | |
608 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); | |
609 | ||
610 | public_key = RSA_new(); | |
611 | sensitive_data.private_key = RSA_new(); | |
612 | ||
a8be9f80 | 613 | /* XXX check options.protocol */ |
5260325f | 614 | log("Generating %d bit RSA key.", options.server_key_bits); |
615 | rsa_generate_key(sensitive_data.private_key, public_key, | |
616 | options.server_key_bits); | |
617 | arc4random_stir(); | |
618 | log("RSA key generation complete."); | |
619 | } else { | |
48e671d5 | 620 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
621 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
622 | continue; | |
623 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
624 | fatal("Too many listen sockets. " | |
625 | "Enlarge MAX_LISTEN_SOCKS"); | |
626 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
627 | ntop, sizeof(ntop), strport, sizeof(strport), | |
628 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
629 | error("getnameinfo failed"); | |
630 | continue; | |
631 | } | |
632 | /* Create socket for listening. */ | |
633 | listen_sock = socket(ai->ai_family, SOCK_STREAM, 0); | |
634 | if (listen_sock < 0) { | |
635 | /* kernel may not support ipv6 */ | |
636 | verbose("socket: %.100s", strerror(errno)); | |
637 | continue; | |
638 | } | |
639 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
640 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
641 | close(listen_sock); | |
642 | continue; | |
643 | } | |
644 | /* | |
645 | * Set socket options. We try to make the port | |
646 | * reusable and have it close as fast as possible | |
647 | * without waiting in unnecessary wait states on | |
648 | * close. | |
649 | */ | |
650 | setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, | |
651 | (void *) &on, sizeof(on)); | |
652 | linger.l_onoff = 1; | |
653 | linger.l_linger = 5; | |
654 | setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, | |
655 | (void *) &linger, sizeof(linger)); | |
656 | ||
657 | debug("Bind to port %s on %s.", strport, ntop); | |
658 | ||
659 | /* Bind the socket to the desired port. */ | |
16218745 | 660 | if ((bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) && |
661 | (!ai->ai_next)) { | |
48e671d5 | 662 | error("Bind to port %s on %s failed: %.200s.", |
663 | strport, ntop, strerror(errno)); | |
664 | close(listen_sock); | |
665 | continue; | |
666 | } | |
667 | listen_socks[num_listen_socks] = listen_sock; | |
668 | num_listen_socks++; | |
669 | ||
670 | /* Start listening on the port. */ | |
671 | log("Server listening on %s port %s.", ntop, strport); | |
672 | if (listen(listen_sock, 5) < 0) | |
673 | fatal("listen: %.100s", strerror(errno)); | |
674 | ||
5260325f | 675 | } |
48e671d5 | 676 | freeaddrinfo(options.listen_addrs); |
677 | ||
678 | if (!num_listen_socks) | |
679 | fatal("Cannot bind any address."); | |
680 | ||
5260325f | 681 | if (!debug_flag) { |
aa3378df | 682 | /* |
683 | * Record our pid in /etc/sshd_pid to make it easier | |
684 | * to kill the correct sshd. We don\'t want to do | |
685 | * this before the bind above because the bind will | |
686 | * fail if there already is a daemon, and this will | |
687 | * overwrite any old pid in the file. | |
688 | */ | |
5260325f | 689 | f = fopen(SSH_DAEMON_PID_FILE, "w"); |
690 | if (f) { | |
691 | fprintf(f, "%u\n", (unsigned int) getpid()); | |
692 | fclose(f); | |
693 | } | |
8efc0c15 | 694 | } |
8efc0c15 | 695 | |
5260325f | 696 | public_key = RSA_new(); |
697 | sensitive_data.private_key = RSA_new(); | |
698 | ||
699 | log("Generating %d bit RSA key.", options.server_key_bits); | |
700 | rsa_generate_key(sensitive_data.private_key, public_key, | |
701 | options.server_key_bits); | |
702 | arc4random_stir(); | |
703 | log("RSA key generation complete."); | |
704 | ||
705 | /* Schedule server key regeneration alarm. */ | |
706 | signal(SIGALRM, key_regeneration_alarm); | |
707 | alarm(options.key_regeneration_time); | |
708 | ||
709 | /* Arrange to restart on SIGHUP. The handler needs listen_sock. */ | |
710 | signal(SIGHUP, sighup_handler); | |
711 | signal(SIGTERM, sigterm_handler); | |
712 | signal(SIGQUIT, sigterm_handler); | |
713 | ||
714 | /* Arrange SIGCHLD to be caught. */ | |
715 | signal(SIGCHLD, main_sigchld_handler); | |
716 | ||
48e671d5 | 717 | /* setup fd set for listen */ |
718 | maxfd = 0; | |
719 | for (i = 0; i < num_listen_socks; i++) | |
720 | if (listen_socks[i] > maxfd) | |
721 | maxfd = listen_socks[i]; | |
722 | fdsetsz = howmany(maxfd, NFDBITS) * sizeof(fd_mask); | |
723 | fdset = (fd_set *)xmalloc(fdsetsz); | |
724 | ||
aa3378df | 725 | /* |
726 | * Stay listening for connections until the system crashes or | |
727 | * the daemon is killed with a signal. | |
728 | */ | |
5260325f | 729 | for (;;) { |
730 | if (received_sighup) | |
731 | sighup_restart(); | |
48e671d5 | 732 | /* Wait in select until there is a connection. */ |
733 | memset(fdset, 0, fdsetsz); | |
734 | for (i = 0; i < num_listen_socks; i++) | |
735 | FD_SET(listen_socks[i], fdset); | |
736 | if (select(maxfd + 1, fdset, NULL, NULL, NULL) < 0) { | |
737 | if (errno != EINTR) | |
738 | error("select: %.100s", strerror(errno)); | |
2d86a6cc | 739 | continue; |
48e671d5 | 740 | } |
741 | for (i = 0; i < num_listen_socks; i++) { | |
742 | if (!FD_ISSET(listen_socks[i], fdset)) | |
5260325f | 743 | continue; |
48e671d5 | 744 | fromlen = sizeof(from); |
745 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
746 | &fromlen); | |
747 | if (newsock < 0) { | |
748 | if (errno != EINTR && errno != EWOULDBLOCK) | |
749 | error("accept: %.100s", strerror(errno)); | |
750 | continue; | |
751 | } | |
752 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
753 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
5260325f | 754 | continue; |
755 | } | |
aa3378df | 756 | /* |
757 | * Got connection. Fork a child to handle it, unless | |
758 | * we are in debugging mode. | |
759 | */ | |
5260325f | 760 | if (debug_flag) { |
aa3378df | 761 | /* |
762 | * In debugging mode. Close the listening | |
763 | * socket, and start processing the | |
764 | * connection without forking. | |
765 | */ | |
5260325f | 766 | debug("Server will not fork when running in debugging mode."); |
48e671d5 | 767 | close_listen_socks(); |
5260325f | 768 | sock_in = newsock; |
769 | sock_out = newsock; | |
770 | pid = getpid(); | |
771 | break; | |
772 | } else { | |
aa3378df | 773 | /* |
774 | * Normal production daemon. Fork, and have | |
775 | * the child process the connection. The | |
776 | * parent continues listening. | |
777 | */ | |
5260325f | 778 | if ((pid = fork()) == 0) { |
aa3378df | 779 | /* |
780 | * Child. Close the listening socket, and start using the | |
781 | * accepted socket. Reinitialize logging (since our pid has | |
782 | * changed). We break out of the loop to handle the connection. | |
783 | */ | |
48e671d5 | 784 | close_listen_socks(); |
5260325f | 785 | sock_in = newsock; |
786 | sock_out = newsock; | |
787 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
788 | break; | |
789 | } | |
790 | } | |
791 | ||
792 | /* Parent. Stay in the loop. */ | |
793 | if (pid < 0) | |
794 | error("fork: %.100s", strerror(errno)); | |
795 | else | |
796 | debug("Forked child %d.", pid); | |
797 | ||
798 | /* Mark that the key has been used (it was "given" to the child). */ | |
799 | key_used = 1; | |
800 | ||
801 | arc4random_stir(); | |
802 | ||
803 | /* Close the new socket (the child is now taking care of it). */ | |
804 | close(newsock); | |
48e671d5 | 805 | } /* for (i = 0; i < num_listen_socks; i++) */ |
806 | /* child process check (or debug mode) */ | |
807 | if (num_listen_socks < 0) | |
808 | break; | |
5260325f | 809 | } |
810 | } | |
8efc0c15 | 811 | |
5260325f | 812 | /* This is the child processing a new connection. */ |
813 | ||
aa3378df | 814 | /* |
815 | * Disable the key regeneration alarm. We will not regenerate the | |
816 | * key since we are no longer in a position to give it to anyone. We | |
817 | * will not restart on SIGHUP since it no longer makes sense. | |
818 | */ | |
5260325f | 819 | alarm(0); |
820 | signal(SIGALRM, SIG_DFL); | |
821 | signal(SIGHUP, SIG_DFL); | |
822 | signal(SIGTERM, SIG_DFL); | |
823 | signal(SIGQUIT, SIG_DFL); | |
824 | signal(SIGCHLD, SIG_DFL); | |
825 | ||
aa3378df | 826 | /* |
827 | * Set socket options for the connection. We want the socket to | |
828 | * close as fast as possible without waiting for anything. If the | |
829 | * connection is not a socket, these will do nothing. | |
830 | */ | |
831 | /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 832 | linger.l_onoff = 1; |
833 | linger.l_linger = 5; | |
834 | setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
835 | ||
aa3378df | 836 | /* |
837 | * Register our connection. This turns encryption off because we do | |
838 | * not have a key. | |
839 | */ | |
5260325f | 840 | packet_set_connection(sock_in, sock_out); |
841 | ||
842 | remote_port = get_remote_port(); | |
843 | remote_ip = get_remote_ipaddr(); | |
844 | ||
845 | /* Check whether logins are denied from this host. */ | |
846 | #ifdef LIBWRAP | |
48e671d5 | 847 | /* XXX LIBWRAP noes not know about IPv6 */ |
5260325f | 848 | { |
849 | struct request_info req; | |
8efc0c15 | 850 | |
5260325f | 851 | request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL); |
852 | fromhost(&req); | |
8efc0c15 | 853 | |
5260325f | 854 | if (!hosts_access(&req)) { |
855 | close(sock_in); | |
856 | close(sock_out); | |
857 | refuse(&req); | |
858 | } | |
48e671d5 | 859 | /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */ |
8efc0c15 | 860 | } |
48e671d5 | 861 | #endif /* LIBWRAP */ |
5260325f | 862 | /* Log the connection. */ |
863 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
8efc0c15 | 864 | |
aa3378df | 865 | /* |
866 | * We don\'t want to listen forever unless the other side | |
867 | * successfully authenticates itself. So we set up an alarm which is | |
868 | * cleared after successful authentication. A limit of zero | |
869 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
870 | * mode; it is just annoying to have the server exit just when you | |
871 | * are about to discover the bug. | |
872 | */ | |
5260325f | 873 | signal(SIGALRM, grace_alarm_handler); |
874 | if (!debug_flag) | |
875 | alarm(options.login_grace_time); | |
876 | ||
7368a6c8 | 877 | sshd_exchange_identification(sock_in, sock_out); |
aa3378df | 878 | /* |
879 | * Check that the connection comes from a privileged port. Rhosts- | |
880 | * and Rhosts-RSA-Authentication only make sense from priviledged | |
881 | * programs. Of course, if the intruder has root access on his local | |
882 | * machine, he can connect from any port. So do not use these | |
883 | * authentication methods from machines that you do not trust. | |
884 | */ | |
5260325f | 885 | if (remote_port >= IPPORT_RESERVED || |
886 | remote_port < IPPORT_RESERVED / 2) { | |
887 | options.rhosts_authentication = 0; | |
888 | options.rhosts_rsa_authentication = 0; | |
889 | } | |
48e671d5 | 890 | #ifdef KRB4 |
891 | if (!packet_connection_is_ipv4() && | |
892 | options.kerberos_authentication) { | |
893 | debug("Kerberos Authentication disabled, only available for IPv4."); | |
894 | options.kerberos_authentication = 0; | |
895 | } | |
896 | #endif /* KRB4 */ | |
897 | ||
5260325f | 898 | packet_set_nonblocking(); |
899 | ||
7b2ea3a1 | 900 | /* perform the key exchange */ |
7b2ea3a1 | 901 | /* authenticate user and start session */ |
e78a59f5 | 902 | if (compat20) { |
903 | do_ssh2_kex(); | |
904 | do_authentication2(); | |
905 | } else { | |
906 | do_ssh1_kex(); | |
907 | do_authentication(); | |
908 | } | |
8efc0c15 | 909 | |
910 | #ifdef KRB4 | |
5260325f | 911 | /* Cleanup user's ticket cache file. */ |
912 | if (options.kerberos_ticket_cleanup) | |
913 | (void) dest_tkt(); | |
8efc0c15 | 914 | #endif /* KRB4 */ |
915 | ||
5260325f | 916 | /* The connection has been terminated. */ |
917 | verbose("Closing connection to %.100s", remote_ip); | |
8efc0c15 | 918 | |
d94aa2ae | 919 | #ifdef USE_PAM |
a5c9cd31 | 920 | finish_pam(); |
d94aa2ae | 921 | #endif /* USE_PAM */ |
8efc0c15 | 922 | |
5260325f | 923 | packet_close(); |
924 | exit(0); | |
925 | } | |
8efc0c15 | 926 | |
5260325f | 927 | /* |
7b2ea3a1 | 928 | * SSH1 key exchange |
5260325f | 929 | */ |
e7c0f9d5 | 930 | void |
7368a6c8 | 931 | do_ssh1_kex() |
8efc0c15 | 932 | { |
5260325f | 933 | int i, len; |
7b2ea3a1 | 934 | int plen, slen; |
5260325f | 935 | BIGNUM *session_key_int; |
936 | unsigned char session_key[SSH_SESSION_KEY_LENGTH]; | |
7b2ea3a1 | 937 | unsigned char cookie[8]; |
5260325f | 938 | unsigned int cipher_type, auth_mask, protocol_flags; |
5260325f | 939 | u_int32_t rand = 0; |
940 | ||
aa3378df | 941 | /* |
942 | * Generate check bytes that the client must send back in the user | |
943 | * packet in order for it to be accepted; this is used to defy ip | |
944 | * spoofing attacks. Note that this only works against somebody | |
945 | * doing IP spoofing from a remote machine; any machine on the local | |
946 | * network can still see outgoing packets and catch the random | |
947 | * cookie. This only affects rhosts authentication, and this is one | |
948 | * of the reasons why it is inherently insecure. | |
949 | */ | |
5260325f | 950 | for (i = 0; i < 8; i++) { |
951 | if (i % 4 == 0) | |
952 | rand = arc4random(); | |
7b2ea3a1 | 953 | cookie[i] = rand & 0xff; |
5260325f | 954 | rand >>= 8; |
955 | } | |
956 | ||
aa3378df | 957 | /* |
958 | * Send our public key. We include in the packet 64 bits of random | |
959 | * data that must be matched in the reply in order to prevent IP | |
960 | * spoofing. | |
961 | */ | |
5260325f | 962 | packet_start(SSH_SMSG_PUBLIC_KEY); |
963 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 964 | packet_put_char(cookie[i]); |
5260325f | 965 | |
966 | /* Store our public server RSA key. */ | |
967 | packet_put_int(BN_num_bits(public_key->n)); | |
968 | packet_put_bignum(public_key->e); | |
969 | packet_put_bignum(public_key->n); | |
970 | ||
971 | /* Store our public host RSA key. */ | |
972 | packet_put_int(BN_num_bits(sensitive_data.host_key->n)); | |
973 | packet_put_bignum(sensitive_data.host_key->e); | |
974 | packet_put_bignum(sensitive_data.host_key->n); | |
975 | ||
976 | /* Put protocol flags. */ | |
977 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
978 | ||
979 | /* Declare which ciphers we support. */ | |
8ce64345 | 980 | packet_put_int(cipher_mask1()); |
5260325f | 981 | |
982 | /* Declare supported authentication types. */ | |
983 | auth_mask = 0; | |
984 | if (options.rhosts_authentication) | |
985 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
986 | if (options.rhosts_rsa_authentication) | |
987 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
988 | if (options.rsa_authentication) | |
989 | auth_mask |= 1 << SSH_AUTH_RSA; | |
8efc0c15 | 990 | #ifdef KRB4 |
5260325f | 991 | if (options.kerberos_authentication) |
992 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
8efc0c15 | 993 | #endif |
994 | #ifdef AFS | |
5260325f | 995 | if (options.kerberos_tgt_passing) |
996 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
997 | if (options.afs_token_passing) | |
998 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
8efc0c15 | 999 | #endif |
5260325f | 1000 | #ifdef SKEY |
1001 | if (options.skey_authentication == 1) | |
1002 | auth_mask |= 1 << SSH_AUTH_TIS; | |
1003 | #endif | |
1004 | if (options.password_authentication) | |
1005 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1006 | packet_put_int(auth_mask); | |
1007 | ||
1008 | /* Send the packet and wait for it to be sent. */ | |
1009 | packet_send(); | |
1010 | packet_write_wait(); | |
1011 | ||
1012 | debug("Sent %d bit public key and %d bit host key.", | |
1013 | BN_num_bits(public_key->n), BN_num_bits(sensitive_data.host_key->n)); | |
1014 | ||
1015 | /* Read clients reply (cipher type and session key). */ | |
1016 | packet_read_expect(&plen, SSH_CMSG_SESSION_KEY); | |
1017 | ||
2d86a6cc | 1018 | /* Get cipher type and check whether we accept this. */ |
5260325f | 1019 | cipher_type = packet_get_char(); |
1020 | ||
2d86a6cc | 1021 | if (!(cipher_mask() & (1 << cipher_type))) |
1022 | packet_disconnect("Warning: client selects unsupported cipher."); | |
1023 | ||
5260325f | 1024 | /* Get check bytes from the packet. These must match those we |
1025 | sent earlier with the public key packet. */ | |
1026 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1027 | if (cookie[i] != packet_get_char()) |
5260325f | 1028 | packet_disconnect("IP Spoofing check bytes do not match."); |
1029 | ||
1030 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1031 | ||
1032 | /* Get the encrypted integer. */ | |
1033 | session_key_int = BN_new(); | |
1034 | packet_get_bignum(session_key_int, &slen); | |
1035 | ||
5260325f | 1036 | protocol_flags = packet_get_int(); |
1037 | packet_set_protocol_flags(protocol_flags); | |
1038 | ||
1039 | packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY); | |
1040 | ||
aa3378df | 1041 | /* |
1042 | * Decrypt it using our private server key and private host key (key | |
1043 | * with larger modulus first). | |
1044 | */ | |
5260325f | 1045 | if (BN_cmp(sensitive_data.private_key->n, sensitive_data.host_key->n) > 0) { |
1046 | /* Private key has bigger modulus. */ | |
1047 | if (BN_num_bits(sensitive_data.private_key->n) < | |
1048 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) { | |
1049 | fatal("do_connection: %s: private_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1050 | get_remote_ipaddr(), | |
1051 | BN_num_bits(sensitive_data.private_key->n), | |
1052 | BN_num_bits(sensitive_data.host_key->n), | |
1053 | SSH_KEY_BITS_RESERVED); | |
1054 | } | |
1055 | rsa_private_decrypt(session_key_int, session_key_int, | |
1056 | sensitive_data.private_key); | |
1057 | rsa_private_decrypt(session_key_int, session_key_int, | |
1058 | sensitive_data.host_key); | |
1059 | } else { | |
1060 | /* Host key has bigger modulus (or they are equal). */ | |
1061 | if (BN_num_bits(sensitive_data.host_key->n) < | |
1062 | BN_num_bits(sensitive_data.private_key->n) + SSH_KEY_BITS_RESERVED) { | |
1063 | fatal("do_connection: %s: host_key %d < private_key %d + SSH_KEY_BITS_RESERVED %d", | |
1064 | get_remote_ipaddr(), | |
1065 | BN_num_bits(sensitive_data.host_key->n), | |
1066 | BN_num_bits(sensitive_data.private_key->n), | |
1067 | SSH_KEY_BITS_RESERVED); | |
1068 | } | |
1069 | rsa_private_decrypt(session_key_int, session_key_int, | |
1070 | sensitive_data.host_key); | |
1071 | rsa_private_decrypt(session_key_int, session_key_int, | |
1072 | sensitive_data.private_key); | |
1073 | } | |
1074 | ||
7b2ea3a1 | 1075 | compute_session_id(session_id, cookie, |
5260325f | 1076 | sensitive_data.host_key->n, |
1077 | sensitive_data.private_key->n); | |
1078 | ||
7b2ea3a1 | 1079 | /* Destroy the private and public keys. They will no longer be needed. */ |
1080 | RSA_free(public_key); | |
1081 | RSA_free(sensitive_data.private_key); | |
1082 | RSA_free(sensitive_data.host_key); | |
1083 | ||
aa3378df | 1084 | /* |
1085 | * Extract session key from the decrypted integer. The key is in the | |
1086 | * least significant 256 bits of the integer; the first byte of the | |
1087 | * key is in the highest bits. | |
1088 | */ | |
5260325f | 1089 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); |
1090 | len = BN_num_bytes(session_key_int); | |
1091 | if (len < 0 || len > sizeof(session_key)) | |
1092 | fatal("do_connection: bad len from %s: session_key_int %d > sizeof(session_key) %d", | |
1093 | get_remote_ipaddr(), | |
1094 | len, sizeof(session_key)); | |
1095 | memset(session_key, 0, sizeof(session_key)); | |
1096 | BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len); | |
1097 | ||
7b2ea3a1 | 1098 | /* Destroy the decrypted integer. It is no longer needed. */ |
1099 | BN_clear_free(session_key_int); | |
1100 | ||
5260325f | 1101 | /* Xor the first 16 bytes of the session key with the session id. */ |
1102 | for (i = 0; i < 16; i++) | |
1103 | session_key[i] ^= session_id[i]; | |
1104 | ||
5260325f | 1105 | /* Set the session key. From this on all communications will be encrypted. */ |
1106 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1107 | ||
1108 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1109 | memset(session_key, 0, sizeof(session_key)); | |
1110 | ||
1111 | debug("Received session key; encryption turned on."); | |
1112 | ||
1113 | /* Send an acknowledgement packet. Note that this packet is sent encrypted. */ | |
1114 | packet_start(SSH_SMSG_SUCCESS); | |
1115 | packet_send(); | |
1116 | packet_write_wait(); | |
5260325f | 1117 | } |
e78a59f5 | 1118 | |
1119 | /* | |
1120 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1121 | */ | |
1122 | void | |
1123 | do_ssh2_kex() | |
1124 | { | |
1125 | Buffer *server_kexinit; | |
1126 | Buffer *client_kexinit; | |
1127 | int payload_len, dlen; | |
1128 | int slen; | |
1129 | unsigned int klen, kout; | |
1130 | char *ptr; | |
1131 | unsigned char *signature = NULL; | |
1132 | unsigned char *server_host_key_blob = NULL; | |
1133 | unsigned int sbloblen; | |
1134 | DH *dh; | |
1135 | BIGNUM *dh_client_pub = 0; | |
1136 | BIGNUM *shared_secret = 0; | |
1137 | int i; | |
1138 | unsigned char *kbuf; | |
1139 | unsigned char *hash; | |
1140 | Kex *kex; | |
1141 | Key *server_host_key; | |
1142 | char *cprop[PROPOSAL_MAX]; | |
1143 | char *sprop[PROPOSAL_MAX]; | |
1144 | ||
1145 | /* KEXINIT */ | |
1146 | ||
a8be9f80 | 1147 | if (options.ciphers != NULL) { |
1148 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
1149 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; | |
1150 | } | |
1151 | ||
e78a59f5 | 1152 | debug("Sending KEX init."); |
1153 | ||
1154 | for (i = 0; i < PROPOSAL_MAX; i++) | |
1155 | sprop[i] = xstrdup(myproposal[i]); | |
1156 | server_kexinit = kex_init(sprop); | |
1157 | packet_start(SSH2_MSG_KEXINIT); | |
1158 | packet_put_raw(buffer_ptr(server_kexinit), buffer_len(server_kexinit)); | |
1159 | packet_send(); | |
1160 | packet_write_wait(); | |
1161 | ||
1162 | debug("done"); | |
1163 | ||
1164 | packet_read_expect(&payload_len, SSH2_MSG_KEXINIT); | |
1165 | ||
1166 | /* | |
1167 | * save raw KEXINIT payload in buffer. this is used during | |
1168 | * computation of the session_id and the session keys. | |
1169 | */ | |
1170 | client_kexinit = xmalloc(sizeof(*client_kexinit)); | |
1171 | buffer_init(client_kexinit); | |
1172 | ptr = packet_get_raw(&payload_len); | |
1173 | buffer_append(client_kexinit, ptr, payload_len); | |
1174 | ||
1175 | /* skip cookie */ | |
1176 | for (i = 0; i < 16; i++) | |
1177 | (void) packet_get_char(); | |
1178 | /* save kex init proposal strings */ | |
1179 | for (i = 0; i < PROPOSAL_MAX; i++) { | |
1180 | cprop[i] = packet_get_string(NULL); | |
1181 | debug("got kexinit string: %s", cprop[i]); | |
1182 | } | |
1183 | ||
1184 | i = (int) packet_get_char(); | |
1185 | debug("first kex follow == %d", i); | |
1186 | i = packet_get_int(); | |
1187 | debug("reserved == %d", i); | |
1188 | ||
1189 | debug("done read kexinit"); | |
1190 | kex = kex_choose_conf(cprop, sprop, 1); | |
1191 | ||
1192 | /* KEXDH */ | |
1193 | ||
1194 | debug("Wait SSH2_MSG_KEXDH_INIT."); | |
1195 | packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT); | |
1196 | ||
1197 | /* key, cert */ | |
1198 | dh_client_pub = BN_new(); | |
1199 | if (dh_client_pub == NULL) | |
1200 | fatal("dh_client_pub == NULL"); | |
1201 | packet_get_bignum2(dh_client_pub, &dlen); | |
1202 | ||
1203 | #ifdef DEBUG_KEXDH | |
1204 | fprintf(stderr, "\ndh_client_pub= "); | |
1205 | bignum_print(dh_client_pub); | |
1206 | fprintf(stderr, "\n"); | |
1207 | debug("bits %d", BN_num_bits(dh_client_pub)); | |
1208 | #endif | |
1209 | ||
1210 | /* generate DH key */ | |
a8be9f80 | 1211 | dh = dh_new_group1(); /* XXX depends on 'kex' */ |
e78a59f5 | 1212 | |
1213 | #ifdef DEBUG_KEXDH | |
1214 | fprintf(stderr, "\np= "); | |
1215 | bignum_print(dh->p); | |
1216 | fprintf(stderr, "\ng= "); | |
1217 | bignum_print(dh->g); | |
1218 | fprintf(stderr, "\npub= "); | |
1219 | bignum_print(dh->pub_key); | |
1220 | fprintf(stderr, "\n"); | |
1221 | #endif | |
a8be9f80 | 1222 | if (!dh_pub_is_valid(dh, dh_client_pub)) |
1223 | packet_disconnect("bad client public DH value"); | |
e78a59f5 | 1224 | |
1225 | klen = DH_size(dh); | |
1226 | kbuf = xmalloc(klen); | |
1227 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | |
1228 | ||
1229 | #ifdef DEBUG_KEXDH | |
1230 | debug("shared secret: len %d/%d", klen, kout); | |
1231 | fprintf(stderr, "shared secret == "); | |
1232 | for (i = 0; i< kout; i++) | |
1233 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
1234 | fprintf(stderr, "\n"); | |
1235 | #endif | |
1236 | shared_secret = BN_new(); | |
1237 | ||
1238 | BN_bin2bn(kbuf, kout, shared_secret); | |
1239 | memset(kbuf, 0, klen); | |
1240 | xfree(kbuf); | |
1241 | ||
1242 | server_host_key = dsa_get_serverkey(options.dsa_key_file); | |
1243 | dsa_make_serverkey_blob(server_host_key, &server_host_key_blob, &sbloblen); | |
1244 | ||
1245 | /* calc H */ /* XXX depends on 'kex' */ | |
1246 | hash = kex_hash( | |
1247 | client_version_string, | |
1248 | server_version_string, | |
1249 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
1250 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
1251 | (char *)server_host_key_blob, sbloblen, | |
1252 | dh_client_pub, | |
1253 | dh->pub_key, | |
1254 | shared_secret | |
1255 | ); | |
1256 | buffer_free(client_kexinit); | |
1257 | buffer_free(server_kexinit); | |
1258 | xfree(client_kexinit); | |
1259 | xfree(server_kexinit); | |
1260 | #ifdef DEBUG_KEXDH | |
1261 | fprintf(stderr, "hash == "); | |
1262 | for (i = 0; i< 20; i++) | |
1263 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
1264 | fprintf(stderr, "\n"); | |
1265 | #endif | |
1266 | /* sign H */ | |
1267 | dsa_sign(server_host_key, &signature, &slen, hash, 20); | |
1268 | /* hashlen depends on KEX */ | |
1269 | key_free(server_host_key); | |
1270 | ||
1271 | /* send server hostkey, DH pubkey 'f' and singed H */ | |
1272 | packet_start(SSH2_MSG_KEXDH_REPLY); | |
1273 | packet_put_string((char *)server_host_key_blob, sbloblen); | |
1274 | packet_put_bignum2(dh->pub_key); // f | |
1275 | packet_put_string((char *)signature, slen); | |
1276 | packet_send(); | |
1277 | packet_write_wait(); | |
1278 | ||
1279 | kex_derive_keys(kex, hash, shared_secret); | |
1280 | packet_set_kex(kex); | |
1281 | ||
1282 | /* have keys, free DH */ | |
1283 | DH_free(dh); | |
1284 | ||
1285 | debug("send SSH2_MSG_NEWKEYS."); | |
1286 | packet_start(SSH2_MSG_NEWKEYS); | |
1287 | packet_send(); | |
1288 | packet_write_wait(); | |
1289 | debug("done: send SSH2_MSG_NEWKEYS."); | |
1290 | ||
1291 | debug("Wait SSH2_MSG_NEWKEYS."); | |
1292 | packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS); | |
1293 | debug("GOT SSH2_MSG_NEWKEYS."); | |
1294 | ||
a8be9f80 | 1295 | #ifdef DEBUG_KEXDH |
e78a59f5 | 1296 | /* send 1st encrypted/maced/compressed message */ |
1297 | packet_start(SSH2_MSG_IGNORE); | |
1298 | packet_put_cstring("markus"); | |
1299 | packet_send(); | |
1300 | packet_write_wait(); | |
a8be9f80 | 1301 | #endif |
e78a59f5 | 1302 | debug("done: KEX2."); |
1303 | } |