]>
Commit | Line | Data |
---|---|---|
8efc0c15 | 1 | /* |
5260325f | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
bcbf86ec | 5 | * This program is the ssh daemon. It listens for connections from clients, |
6 | * and performs authentication, executes use commands or shell, and forwards | |
5260325f | 7 | * information to/from the application to the user client over an encrypted |
bcbf86ec | 8 | * connection. This can also handle forwarding of X11, TCP/IP, and |
9 | * authentication agent connections. | |
e78a59f5 | 10 | * |
bcbf86ec | 11 | * As far as I am concerned, the code I have written for this software |
12 | * can be used freely for any purpose. Any derived versions of this | |
13 | * software must be clearly marked as such, and if the derived work is | |
14 | * incompatible with the protocol description in the RFC file, it must be | |
15 | * called by a name other than "ssh" or "Secure Shell". | |
16 | * | |
17 | * SSH2 implementation: | |
18 | * | |
19 | * Copyright (c) 2000 Markus Friedl. All rights reserved. | |
20 | * | |
21 | * Redistribution and use in source and binary forms, with or without | |
22 | * modification, are permitted provided that the following conditions | |
23 | * are met: | |
24 | * 1. Redistributions of source code must retain the above copyright | |
25 | * notice, this list of conditions and the following disclaimer. | |
26 | * 2. Redistributions in binary form must reproduce the above copyright | |
27 | * notice, this list of conditions and the following disclaimer in the | |
28 | * documentation and/or other materials provided with the distribution. | |
29 | * | |
30 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
31 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
32 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
33 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
34 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
35 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
36 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
37 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
38 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
39 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
5260325f | 40 | */ |
8efc0c15 | 41 | |
42 | #include "includes.h" | |
94ec8c6b | 43 | RCSID("$OpenBSD: sshd.c,v 1.132 2000/10/13 18:34:46 markus Exp $"); |
8efc0c15 | 44 | |
45 | #include "xmalloc.h" | |
46 | #include "rsa.h" | |
47 | #include "ssh.h" | |
48 | #include "pty.h" | |
49 | #include "packet.h" | |
8efc0c15 | 50 | #include "mpaux.h" |
51 | #include "servconf.h" | |
52 | #include "uidswap.h" | |
53 | #include "compat.h" | |
7368a6c8 | 54 | #include "buffer.h" |
55 | ||
e78a59f5 | 56 | #include "ssh2.h" |
35484284 | 57 | #include <openssl/dh.h> |
58 | #include <openssl/bn.h> | |
59 | #include <openssl/hmac.h> | |
e78a59f5 | 60 | #include "kex.h" |
35484284 | 61 | #include <openssl/dsa.h> |
62 | #include <openssl/rsa.h> | |
7368a6c8 | 63 | #include "key.h" |
e78a59f5 | 64 | #include "dsa.h" |
94ec8c6b | 65 | #include "dh.h" |
7368a6c8 | 66 | |
67 | #include "auth.h" | |
e78a59f5 | 68 | #include "myproposal.h" |
a306f2dd | 69 | #include "authfile.h" |
8efc0c15 | 70 | |
71 | #ifdef LIBWRAP | |
72 | #include <tcpd.h> | |
73 | #include <syslog.h> | |
74 | int allow_severity = LOG_INFO; | |
75 | int deny_severity = LOG_WARNING; | |
76 | #endif /* LIBWRAP */ | |
77 | ||
78 | #ifndef O_NOCTTY | |
79 | #define O_NOCTTY 0 | |
80 | #endif | |
81 | ||
8efc0c15 | 82 | /* Server configuration options. */ |
83 | ServerOptions options; | |
84 | ||
85 | /* Name of the server configuration file. */ | |
86 | char *config_file_name = SERVER_CONFIG_FILE; | |
87 | ||
6ae2364d | 88 | /* |
48e671d5 | 89 | * Flag indicating whether IPv4 or IPv6. This can be set on the command line. |
90 | * Default value is AF_UNSPEC means both IPv4 and IPv6. | |
91 | */ | |
59e76f33 | 92 | #ifdef IPV4_DEFAULT |
93 | int IPv4or6 = AF_INET; | |
94 | #else | |
48e671d5 | 95 | int IPv4or6 = AF_UNSPEC; |
59e76f33 | 96 | #endif |
48e671d5 | 97 | |
5260325f | 98 | /* |
99 | * Debug mode flag. This can be set on the command line. If debug | |
100 | * mode is enabled, extra debugging output will be sent to the system | |
101 | * log, the daemon will not go to background, and will exit after processing | |
102 | * the first connection. | |
103 | */ | |
8efc0c15 | 104 | int debug_flag = 0; |
105 | ||
106 | /* Flag indicating that the daemon is being started from inetd. */ | |
107 | int inetd_flag = 0; | |
108 | ||
6a17f9c2 | 109 | /* debug goes to stderr unless inetd_flag is set */ |
110 | int log_stderr = 0; | |
111 | ||
8efc0c15 | 112 | /* argv[0] without path. */ |
113 | char *av0; | |
114 | ||
115 | /* Saved arguments to main(). */ | |
116 | char **saved_argv; | |
4d33e531 | 117 | int saved_argc; |
8efc0c15 | 118 | |
aa3378df | 119 | /* |
48e671d5 | 120 | * The sockets that the server is listening; this is used in the SIGHUP |
121 | * signal handler. | |
aa3378df | 122 | */ |
48e671d5 | 123 | #define MAX_LISTEN_SOCKS 16 |
124 | int listen_socks[MAX_LISTEN_SOCKS]; | |
125 | int num_listen_socks = 0; | |
8efc0c15 | 126 | |
aa3378df | 127 | /* |
128 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
129 | * sshd will skip the version-number exchange | |
130 | */ | |
5260325f | 131 | char *client_version_string = NULL; |
7368a6c8 | 132 | char *server_version_string = NULL; |
8efc0c15 | 133 | |
aa3378df | 134 | /* |
135 | * Any really sensitive data in the application is contained in this | |
136 | * structure. The idea is that this structure could be locked into memory so | |
137 | * that the pages do not get written into swap. However, there are some | |
138 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
139 | * have access to the internals of them, and locking just the structure is | |
140 | * not very useful. Currently, memory locking is not implemented. | |
141 | */ | |
5260325f | 142 | struct { |
a306f2dd | 143 | RSA *private_key; /* Private part of empheral server key. */ |
5260325f | 144 | RSA *host_key; /* Private part of host key. */ |
a306f2dd | 145 | Key *dsa_host_key; /* Private DSA host key. */ |
8efc0c15 | 146 | } sensitive_data; |
147 | ||
aa3378df | 148 | /* |
149 | * Flag indicating whether the current session key has been used. This flag | |
150 | * is set whenever the key is used, and cleared when the key is regenerated. | |
151 | */ | |
8efc0c15 | 152 | int key_used = 0; |
153 | ||
154 | /* This is set to true when SIGHUP is received. */ | |
155 | int received_sighup = 0; | |
156 | ||
157 | /* Public side of the server key. This value is regenerated regularly with | |
158 | the private key. */ | |
159 | RSA *public_key; | |
160 | ||
7368a6c8 | 161 | /* session identifier, used by RSA-auth */ |
162 | unsigned char session_id[16]; | |
e7c0f9d5 | 163 | |
a306f2dd | 164 | /* same for ssh2 */ |
165 | unsigned char *session_id2 = NULL; | |
166 | int session_id2_len = 0; | |
167 | ||
c345cf9d | 168 | /* record remote hostname or ip */ |
169 | unsigned int utmp_len = MAXHOSTNAMELEN; | |
170 | ||
7368a6c8 | 171 | /* Prototypes for various functions defined later in this file. */ |
172 | void do_ssh1_kex(); | |
e78a59f5 | 173 | void do_ssh2_kex(); |
c8d54615 | 174 | |
94ec8c6b | 175 | void ssh_dh1_server(Kex *, Buffer *_kexinit, Buffer *); |
176 | void ssh_dhgex_server(Kex *, Buffer *_kexinit, Buffer *); | |
177 | ||
48e671d5 | 178 | /* |
179 | * Close all listening sockets | |
180 | */ | |
181 | void | |
182 | close_listen_socks(void) | |
183 | { | |
184 | int i; | |
185 | for (i = 0; i < num_listen_socks; i++) | |
186 | close(listen_socks[i]); | |
187 | num_listen_socks = -1; | |
188 | } | |
189 | ||
5260325f | 190 | /* |
191 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
192 | * the effect is to reread the configuration file (and to regenerate | |
193 | * the server key). | |
194 | */ | |
6ae2364d | 195 | void |
5260325f | 196 | sighup_handler(int sig) |
8efc0c15 | 197 | { |
5260325f | 198 | received_sighup = 1; |
199 | signal(SIGHUP, sighup_handler); | |
8efc0c15 | 200 | } |
201 | ||
5260325f | 202 | /* |
203 | * Called from the main program after receiving SIGHUP. | |
204 | * Restarts the server. | |
205 | */ | |
6ae2364d | 206 | void |
5260325f | 207 | sighup_restart() |
8efc0c15 | 208 | { |
5260325f | 209 | log("Received SIGHUP; restarting."); |
48e671d5 | 210 | close_listen_socks(); |
5260325f | 211 | execv(saved_argv[0], saved_argv); |
212 | log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno)); | |
213 | exit(1); | |
8efc0c15 | 214 | } |
215 | ||
5260325f | 216 | /* |
217 | * Generic signal handler for terminating signals in the master daemon. | |
218 | * These close the listen socket; not closing it seems to cause "Address | |
219 | * already in use" problems on some machines, which is inconvenient. | |
220 | */ | |
6ae2364d | 221 | void |
5260325f | 222 | sigterm_handler(int sig) |
8efc0c15 | 223 | { |
5260325f | 224 | log("Received signal %d; terminating.", sig); |
48e671d5 | 225 | close_listen_socks(); |
0fbe8c74 | 226 | unlink(options.pid_file); |
5260325f | 227 | exit(255); |
8efc0c15 | 228 | } |
229 | ||
5260325f | 230 | /* |
231 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
232 | * reap any zombies left by exited c. | |
233 | */ | |
6ae2364d | 234 | void |
5260325f | 235 | main_sigchld_handler(int sig) |
8efc0c15 | 236 | { |
5260325f | 237 | int save_errno = errno; |
238 | int status; | |
5ad13cd7 | 239 | |
5260325f | 240 | while (waitpid(-1, &status, WNOHANG) > 0) |
241 | ; | |
5ad13cd7 | 242 | |
5260325f | 243 | signal(SIGCHLD, main_sigchld_handler); |
244 | errno = save_errno; | |
8efc0c15 | 245 | } |
246 | ||
5260325f | 247 | /* |
248 | * Signal handler for the alarm after the login grace period has expired. | |
249 | */ | |
6ae2364d | 250 | void |
5260325f | 251 | grace_alarm_handler(int sig) |
8efc0c15 | 252 | { |
5260325f | 253 | /* Close the connection. */ |
254 | packet_close(); | |
8efc0c15 | 255 | |
5260325f | 256 | /* Log error and exit. */ |
257 | fatal("Timeout before authentication for %s.", get_remote_ipaddr()); | |
258 | } | |
8efc0c15 | 259 | |
5260325f | 260 | /* |
261 | * Signal handler for the key regeneration alarm. Note that this | |
262 | * alarm only occurs in the daemon waiting for connections, and it does not | |
263 | * do anything with the private key or random state before forking. | |
264 | * Thus there should be no concurrency control/asynchronous execution | |
265 | * problems. | |
266 | */ | |
a306f2dd | 267 | /* XXX do we really want this work to be done in a signal handler ? -m */ |
6ae2364d | 268 | void |
5260325f | 269 | key_regeneration_alarm(int sig) |
270 | { | |
271 | int save_errno = errno; | |
272 | ||
273 | /* Check if we should generate a new key. */ | |
274 | if (key_used) { | |
275 | /* This should really be done in the background. */ | |
276 | log("Generating new %d bit RSA key.", options.server_key_bits); | |
277 | ||
278 | if (sensitive_data.private_key != NULL) | |
279 | RSA_free(sensitive_data.private_key); | |
280 | sensitive_data.private_key = RSA_new(); | |
281 | ||
282 | if (public_key != NULL) | |
283 | RSA_free(public_key); | |
284 | public_key = RSA_new(); | |
285 | ||
286 | rsa_generate_key(sensitive_data.private_key, public_key, | |
287 | options.server_key_bits); | |
288 | arc4random_stir(); | |
289 | key_used = 0; | |
290 | log("RSA key generation complete."); | |
291 | } | |
292 | /* Reschedule the alarm. */ | |
293 | signal(SIGALRM, key_regeneration_alarm); | |
294 | alarm(options.key_regeneration_time); | |
295 | errno = save_errno; | |
296 | } | |
8efc0c15 | 297 | |
7368a6c8 | 298 | void |
299 | sshd_exchange_identification(int sock_in, int sock_out) | |
300 | { | |
a8be9f80 | 301 | int i, mismatch; |
7368a6c8 | 302 | int remote_major, remote_minor; |
a8be9f80 | 303 | int major, minor; |
7368a6c8 | 304 | char *s; |
305 | char buf[256]; /* Must not be larger than remote_version. */ | |
306 | char remote_version[256]; /* Must be at least as big as buf. */ | |
307 | ||
a8be9f80 | 308 | if ((options.protocol & SSH_PROTO_1) && |
309 | (options.protocol & SSH_PROTO_2)) { | |
310 | major = PROTOCOL_MAJOR_1; | |
311 | minor = 99; | |
312 | } else if (options.protocol & SSH_PROTO_2) { | |
313 | major = PROTOCOL_MAJOR_2; | |
314 | minor = PROTOCOL_MINOR_2; | |
315 | } else { | |
316 | major = PROTOCOL_MAJOR_1; | |
317 | minor = PROTOCOL_MINOR_1; | |
318 | } | |
319 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
7368a6c8 | 320 | server_version_string = xstrdup(buf); |
321 | ||
322 | if (client_version_string == NULL) { | |
323 | /* Send our protocol version identification. */ | |
324 | if (atomicio(write, sock_out, server_version_string, strlen(server_version_string)) | |
325 | != strlen(server_version_string)) { | |
326 | log("Could not write ident string to %s.", get_remote_ipaddr()); | |
327 | fatal_cleanup(); | |
328 | } | |
329 | ||
330 | /* Read other side\'s version identification. */ | |
331 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
e5a0294f | 332 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { |
7368a6c8 | 333 | log("Did not receive ident string from %s.", get_remote_ipaddr()); |
334 | fatal_cleanup(); | |
335 | } | |
336 | if (buf[i] == '\r') { | |
337 | buf[i] = '\n'; | |
338 | buf[i + 1] = 0; | |
94ec8c6b | 339 | /* Kludge for F-Secure Macintosh < 1.0.2 */ |
340 | if (i == 12 && | |
341 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
342 | break; | |
7368a6c8 | 343 | continue; |
7368a6c8 | 344 | } |
345 | if (buf[i] == '\n') { | |
346 | /* buf[i] == '\n' */ | |
347 | buf[i + 1] = 0; | |
348 | break; | |
349 | } | |
350 | } | |
351 | buf[sizeof(buf) - 1] = 0; | |
352 | client_version_string = xstrdup(buf); | |
353 | } | |
354 | ||
355 | /* | |
356 | * Check that the versions match. In future this might accept | |
357 | * several versions and set appropriate flags to handle them. | |
358 | */ | |
359 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
360 | &remote_major, &remote_minor, remote_version) != 3) { | |
6ae2364d | 361 | s = "Protocol mismatch.\n"; |
7368a6c8 | 362 | (void) atomicio(write, sock_out, s, strlen(s)); |
363 | close(sock_in); | |
364 | close(sock_out); | |
365 | log("Bad protocol version identification '%.100s' from %s", | |
366 | client_version_string, get_remote_ipaddr()); | |
367 | fatal_cleanup(); | |
368 | } | |
369 | debug("Client protocol version %d.%d; client software version %.100s", | |
370 | remote_major, remote_minor, remote_version); | |
371 | ||
e78a59f5 | 372 | compat_datafellows(remote_version); |
373 | ||
a8be9f80 | 374 | mismatch = 0; |
7368a6c8 | 375 | switch(remote_major) { |
376 | case 1: | |
a306f2dd | 377 | if (remote_minor == 99) { |
378 | if (options.protocol & SSH_PROTO_2) | |
379 | enable_compat20(); | |
380 | else | |
381 | mismatch = 1; | |
382 | break; | |
383 | } | |
a8be9f80 | 384 | if (!(options.protocol & SSH_PROTO_1)) { |
385 | mismatch = 1; | |
386 | break; | |
387 | } | |
7368a6c8 | 388 | if (remote_minor < 3) { |
089fbbd2 | 389 | packet_disconnect("Your ssh version is too old and " |
7368a6c8 | 390 | "is no longer supported. Please install a newer version."); |
391 | } else if (remote_minor == 3) { | |
392 | /* note that this disables agent-forwarding */ | |
393 | enable_compat13(); | |
394 | } | |
a8be9f80 | 395 | break; |
e78a59f5 | 396 | case 2: |
a8be9f80 | 397 | if (options.protocol & SSH_PROTO_2) { |
e78a59f5 | 398 | enable_compat20(); |
399 | break; | |
400 | } | |
401 | /* FALLTHROUGH */ | |
6ae2364d | 402 | default: |
a8be9f80 | 403 | mismatch = 1; |
404 | break; | |
405 | } | |
406 | chop(server_version_string); | |
407 | chop(client_version_string); | |
408 | debug("Local version string %.200s", server_version_string); | |
409 | ||
410 | if (mismatch) { | |
7368a6c8 | 411 | s = "Protocol major versions differ.\n"; |
412 | (void) atomicio(write, sock_out, s, strlen(s)); | |
413 | close(sock_in); | |
414 | close(sock_out); | |
a8be9f80 | 415 | log("Protocol major versions differ for %s: %.200s vs. %.200s", |
416 | get_remote_ipaddr(), | |
417 | server_version_string, client_version_string); | |
7368a6c8 | 418 | fatal_cleanup(); |
7368a6c8 | 419 | } |
a306f2dd | 420 | if (compat20) |
421 | packet_set_ssh2_format(); | |
422 | } | |
423 | ||
424 | ||
425 | void | |
426 | destroy_sensitive_data(void) | |
427 | { | |
428 | /* Destroy the private and public keys. They will no longer be needed. */ | |
afa5ee68 | 429 | if (public_key) |
430 | RSA_free(public_key); | |
431 | if (sensitive_data.private_key) | |
432 | RSA_free(sensitive_data.private_key); | |
433 | if (sensitive_data.host_key) | |
434 | RSA_free(sensitive_data.host_key); | |
a306f2dd | 435 | if (sensitive_data.dsa_host_key != NULL) |
436 | key_free(sensitive_data.dsa_host_key); | |
7368a6c8 | 437 | } |
438 | ||
c345cf9d | 439 | /* |
440 | * returns 1 if connection should be dropped, 0 otherwise. | |
441 | * dropping starts at connection #max_startups_begin with a probability | |
442 | * of (max_startups_rate/100). the probability increases linearly until | |
443 | * all connections are dropped for startups > max_startups | |
444 | */ | |
445 | int | |
446 | drop_connection(int startups) | |
447 | { | |
448 | double p, r; | |
449 | ||
450 | if (startups < options.max_startups_begin) | |
451 | return 0; | |
452 | if (startups >= options.max_startups) | |
453 | return 1; | |
454 | if (options.max_startups_rate == 100) | |
455 | return 1; | |
456 | ||
457 | p = 100 - options.max_startups_rate; | |
458 | p *= startups - options.max_startups_begin; | |
459 | p /= (double) (options.max_startups - options.max_startups_begin); | |
460 | p += options.max_startups_rate; | |
461 | p /= 100.0; | |
462 | r = arc4random() / (double) UINT_MAX; | |
463 | ||
464 | debug("drop_connection: p %g, r %g", p, r); | |
465 | return (r < p) ? 1 : 0; | |
466 | } | |
467 | ||
089fbbd2 | 468 | int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */ |
469 | int startup_pipe; /* in child */ | |
470 | ||
5260325f | 471 | /* |
472 | * Main program for the daemon. | |
473 | */ | |
8efc0c15 | 474 | int |
475 | main(int ac, char **av) | |
476 | { | |
5260325f | 477 | extern char *optarg; |
478 | extern int optind; | |
089fbbd2 | 479 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; |
9da5c3c9 | 480 | pid_t pid; |
48e671d5 | 481 | socklen_t fromlen; |
a306f2dd | 482 | int silent = 0; |
48e671d5 | 483 | fd_set *fdset; |
484 | struct sockaddr_storage from; | |
5260325f | 485 | const char *remote_ip; |
486 | int remote_port; | |
5260325f | 487 | FILE *f; |
488 | struct linger linger; | |
48e671d5 | 489 | struct addrinfo *ai; |
490 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
491 | int listen_sock, maxfd; | |
089fbbd2 | 492 | int startup_p[2]; |
493 | int startups = 0; | |
5260325f | 494 | |
264dce47 | 495 | init_rng(); |
496 | ||
5260325f | 497 | /* Save argv[0]. */ |
4d33e531 | 498 | saved_argc = ac; |
5260325f | 499 | saved_argv = av; |
500 | if (strchr(av[0], '/')) | |
501 | av0 = strrchr(av[0], '/') + 1; | |
502 | else | |
503 | av0 = av[0]; | |
504 | ||
505 | /* Initialize configuration options to their default values. */ | |
506 | initialize_server_options(&options); | |
507 | ||
508 | /* Parse command-line arguments. */ | |
c345cf9d | 509 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:diqQ46")) != EOF) { |
5260325f | 510 | switch (opt) { |
48e671d5 | 511 | case '4': |
512 | IPv4or6 = AF_INET; | |
513 | break; | |
514 | case '6': | |
515 | IPv4or6 = AF_INET6; | |
516 | break; | |
5260325f | 517 | case 'f': |
518 | config_file_name = optarg; | |
519 | break; | |
520 | case 'd': | |
bcbf86ec | 521 | if (0 == debug_flag) { |
522 | debug_flag = 1; | |
523 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
524 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
525 | options.log_level++; | |
526 | } else { | |
527 | fprintf(stderr, "Too high debugging level.\n"); | |
528 | exit(1); | |
529 | } | |
5260325f | 530 | break; |
531 | case 'i': | |
532 | inetd_flag = 1; | |
533 | break; | |
534 | case 'Q': | |
a306f2dd | 535 | silent = 1; |
5260325f | 536 | break; |
537 | case 'q': | |
538 | options.log_level = SYSLOG_LEVEL_QUIET; | |
539 | break; | |
540 | case 'b': | |
541 | options.server_key_bits = atoi(optarg); | |
542 | break; | |
543 | case 'p': | |
48e671d5 | 544 | options.ports_from_cmdline = 1; |
bcbf86ec | 545 | if (options.num_ports >= MAX_PORTS) { |
546 | fprintf(stderr, "too many ports.\n"); | |
547 | exit(1); | |
548 | } | |
48e671d5 | 549 | options.ports[options.num_ports++] = atoi(optarg); |
5260325f | 550 | break; |
551 | case 'g': | |
552 | options.login_grace_time = atoi(optarg); | |
553 | break; | |
554 | case 'k': | |
555 | options.key_regeneration_time = atoi(optarg); | |
556 | break; | |
557 | case 'h': | |
558 | options.host_key_file = optarg; | |
559 | break; | |
560 | case 'V': | |
561 | client_version_string = optarg; | |
562 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
563 | inetd_flag = 1; | |
564 | break; | |
c345cf9d | 565 | case 'u': |
566 | utmp_len = atoi(optarg); | |
567 | break; | |
5260325f | 568 | case '?': |
569 | default: | |
570 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
571 | fprintf(stderr, "Usage: %s [options]\n", av0); | |
572 | fprintf(stderr, "Options:\n"); | |
aa3378df | 573 | fprintf(stderr, " -f file Configuration file (default %s)\n", SERVER_CONFIG_FILE); |
bcbf86ec | 574 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); |
5260325f | 575 | fprintf(stderr, " -i Started from inetd\n"); |
576 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
577 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
578 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
579 | fprintf(stderr, " -g seconds Grace period for authentication (default: 300)\n"); | |
580 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
581 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
48e671d5 | 582 | HOST_KEY_FILE); |
c345cf9d | 583 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); |
48e671d5 | 584 | fprintf(stderr, " -4 Use IPv4 only\n"); |
585 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
5260325f | 586 | exit(1); |
587 | } | |
588 | } | |
589 | ||
48e671d5 | 590 | /* |
591 | * Force logging to stderr until we have loaded the private host | |
592 | * key (unless started from inetd) | |
593 | */ | |
594 | log_init(av0, | |
595 | options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level, | |
596 | options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility, | |
a306f2dd | 597 | !silent && !inetd_flag); |
48e671d5 | 598 | |
5260325f | 599 | /* Read server configuration options from the configuration file. */ |
600 | read_server_config(&options, config_file_name); | |
601 | ||
602 | /* Fill in default values for those options not explicitly set. */ | |
603 | fill_default_server_options(&options); | |
604 | ||
5260325f | 605 | /* Check that there are no remaining arguments. */ |
606 | if (optind < ac) { | |
607 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
608 | exit(1); | |
8efc0c15 | 609 | } |
5260325f | 610 | |
611 | debug("sshd version %.100s", SSH_VERSION); | |
612 | ||
a306f2dd | 613 | sensitive_data.dsa_host_key = NULL; |
614 | sensitive_data.host_key = NULL; | |
615 | ||
616 | /* check if RSA support exists */ | |
617 | if ((options.protocol & SSH_PROTO_1) && | |
618 | rsa_alive() == 0) { | |
619 | log("no RSA support in libssl and libcrypto. See ssl(8)"); | |
620 | log("Disabling protocol version 1"); | |
621 | options.protocol &= ~SSH_PROTO_1; | |
622 | } | |
623 | /* Load the RSA/DSA host key. It must have empty passphrase. */ | |
624 | if (options.protocol & SSH_PROTO_1) { | |
625 | Key k; | |
626 | sensitive_data.host_key = RSA_new(); | |
627 | k.type = KEY_RSA; | |
628 | k.rsa = sensitive_data.host_key; | |
629 | errno = 0; | |
630 | if (!load_private_key(options.host_key_file, "", &k, NULL)) { | |
631 | error("Could not load host key: %.200s: %.100s", | |
632 | options.host_key_file, strerror(errno)); | |
633 | log("Disabling protocol version 1"); | |
634 | options.protocol &= ~SSH_PROTO_1; | |
635 | } | |
636 | k.rsa = NULL; | |
637 | } | |
638 | if (options.protocol & SSH_PROTO_2) { | |
639 | sensitive_data.dsa_host_key = key_new(KEY_DSA); | |
1d1ffb87 | 640 | if (!load_private_key(options.host_dsa_key_file, "", sensitive_data.dsa_host_key, NULL)) { |
641 | ||
642 | error("Could not load DSA host key: %.200s", options.host_dsa_key_file); | |
a306f2dd | 643 | log("Disabling protocol version 2"); |
644 | options.protocol &= ~SSH_PROTO_2; | |
645 | } | |
646 | } | |
647 | if (! options.protocol & (SSH_PROTO_1|SSH_PROTO_2)) { | |
648 | if (silent == 0) | |
649 | fprintf(stderr, "sshd: no hostkeys available -- exiting.\n"); | |
650 | log("sshd: no hostkeys available -- exiting.\n"); | |
5260325f | 651 | exit(1); |
652 | } | |
5260325f | 653 | |
a306f2dd | 654 | /* Check certain values for sanity. */ |
655 | if (options.protocol & SSH_PROTO_1) { | |
656 | if (options.server_key_bits < 512 || | |
657 | options.server_key_bits > 32768) { | |
658 | fprintf(stderr, "Bad server key size.\n"); | |
659 | exit(1); | |
660 | } | |
661 | /* | |
662 | * Check that server and host key lengths differ sufficiently. This | |
663 | * is necessary to make double encryption work with rsaref. Oh, I | |
664 | * hate software patents. I dont know if this can go? Niels | |
665 | */ | |
666 | if (options.server_key_bits > | |
667 | BN_num_bits(sensitive_data.host_key->n) - SSH_KEY_BITS_RESERVED && | |
668 | options.server_key_bits < | |
669 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) { | |
670 | options.server_key_bits = | |
671 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED; | |
672 | debug("Forcing server key to %d bits to make it differ from host key.", | |
673 | options.server_key_bits); | |
674 | } | |
675 | } | |
676 | ||
77bb0bca | 677 | #ifdef HAVE_SCO_PROTECTED_PW |
678 | (void) set_auth_parameters(ac, av); | |
679 | #endif | |
680 | ||
a306f2dd | 681 | /* Initialize the log (it is reinitialized below in case we forked). */ |
5260325f | 682 | if (debug_flag && !inetd_flag) |
683 | log_stderr = 1; | |
684 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
685 | ||
a306f2dd | 686 | /* |
687 | * If not in debugging mode, and not started from inetd, disconnect | |
688 | * from the controlling terminal, and fork. The original process | |
689 | * exits. | |
690 | */ | |
5260325f | 691 | if (!debug_flag && !inetd_flag) { |
8efc0c15 | 692 | #ifdef TIOCNOTTY |
5260325f | 693 | int fd; |
8efc0c15 | 694 | #endif /* TIOCNOTTY */ |
5260325f | 695 | if (daemon(0, 0) < 0) |
696 | fatal("daemon() failed: %.200s", strerror(errno)); | |
697 | ||
698 | /* Disconnect from the controlling tty. */ | |
8efc0c15 | 699 | #ifdef TIOCNOTTY |
5260325f | 700 | fd = open("/dev/tty", O_RDWR | O_NOCTTY); |
701 | if (fd >= 0) { | |
702 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
703 | close(fd); | |
704 | } | |
8efc0c15 | 705 | #endif /* TIOCNOTTY */ |
8efc0c15 | 706 | } |
5260325f | 707 | /* Reinitialize the log (because of the fork above). */ |
708 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
709 | ||
5260325f | 710 | /* Do not display messages to stdout in RSA code. */ |
711 | rsa_set_verbose(0); | |
712 | ||
713 | /* Initialize the random number generator. */ | |
714 | arc4random_stir(); | |
715 | ||
716 | /* Chdir to the root directory so that the current disk can be | |
717 | unmounted if desired. */ | |
718 | chdir("/"); | |
719 | ||
5260325f | 720 | /* Start listening for a socket, unless started from inetd. */ |
721 | if (inetd_flag) { | |
722 | int s1, s2; | |
723 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ | |
724 | s2 = dup(s1); | |
725 | sock_in = dup(0); | |
726 | sock_out = dup(1); | |
4c8722d9 | 727 | startup_pipe = -1; |
a306f2dd | 728 | /* |
729 | * We intentionally do not close the descriptors 0, 1, and 2 | |
730 | * as our code for setting the descriptors won\'t work if | |
731 | * ttyfd happens to be one of those. | |
732 | */ | |
5260325f | 733 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); |
734 | ||
a306f2dd | 735 | if (options.protocol & SSH_PROTO_1) { |
736 | public_key = RSA_new(); | |
737 | sensitive_data.private_key = RSA_new(); | |
738 | log("Generating %d bit RSA key.", options.server_key_bits); | |
739 | rsa_generate_key(sensitive_data.private_key, public_key, | |
740 | options.server_key_bits); | |
741 | arc4random_stir(); | |
742 | log("RSA key generation complete."); | |
743 | } | |
5260325f | 744 | } else { |
48e671d5 | 745 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
746 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
747 | continue; | |
748 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
749 | fatal("Too many listen sockets. " | |
750 | "Enlarge MAX_LISTEN_SOCKS"); | |
751 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
752 | ntop, sizeof(ntop), strport, sizeof(strport), | |
753 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
754 | error("getnameinfo failed"); | |
755 | continue; | |
756 | } | |
757 | /* Create socket for listening. */ | |
758 | listen_sock = socket(ai->ai_family, SOCK_STREAM, 0); | |
759 | if (listen_sock < 0) { | |
760 | /* kernel may not support ipv6 */ | |
761 | verbose("socket: %.100s", strerror(errno)); | |
762 | continue; | |
763 | } | |
764 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
765 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
766 | close(listen_sock); | |
767 | continue; | |
768 | } | |
769 | /* | |
770 | * Set socket options. We try to make the port | |
771 | * reusable and have it close as fast as possible | |
772 | * without waiting in unnecessary wait states on | |
773 | * close. | |
774 | */ | |
775 | setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, | |
776 | (void *) &on, sizeof(on)); | |
777 | linger.l_onoff = 1; | |
778 | linger.l_linger = 5; | |
779 | setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, | |
780 | (void *) &linger, sizeof(linger)); | |
781 | ||
782 | debug("Bind to port %s on %s.", strport, ntop); | |
783 | ||
784 | /* Bind the socket to the desired port. */ | |
16218745 | 785 | if ((bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) && |
786 | (!ai->ai_next)) { | |
48e671d5 | 787 | error("Bind to port %s on %s failed: %.200s.", |
788 | strport, ntop, strerror(errno)); | |
789 | close(listen_sock); | |
790 | continue; | |
791 | } | |
792 | listen_socks[num_listen_socks] = listen_sock; | |
793 | num_listen_socks++; | |
794 | ||
795 | /* Start listening on the port. */ | |
796 | log("Server listening on %s port %s.", ntop, strport); | |
797 | if (listen(listen_sock, 5) < 0) | |
798 | fatal("listen: %.100s", strerror(errno)); | |
799 | ||
5260325f | 800 | } |
48e671d5 | 801 | freeaddrinfo(options.listen_addrs); |
802 | ||
803 | if (!num_listen_socks) | |
804 | fatal("Cannot bind any address."); | |
805 | ||
5260325f | 806 | if (!debug_flag) { |
aa3378df | 807 | /* |
808 | * Record our pid in /etc/sshd_pid to make it easier | |
809 | * to kill the correct sshd. We don\'t want to do | |
810 | * this before the bind above because the bind will | |
811 | * fail if there already is a daemon, and this will | |
812 | * overwrite any old pid in the file. | |
813 | */ | |
3c62e7eb | 814 | f = fopen(options.pid_file, "wb"); |
5260325f | 815 | if (f) { |
816 | fprintf(f, "%u\n", (unsigned int) getpid()); | |
817 | fclose(f); | |
818 | } | |
8efc0c15 | 819 | } |
a306f2dd | 820 | if (options.protocol & SSH_PROTO_1) { |
821 | public_key = RSA_new(); | |
822 | sensitive_data.private_key = RSA_new(); | |
8efc0c15 | 823 | |
a306f2dd | 824 | log("Generating %d bit RSA key.", options.server_key_bits); |
825 | rsa_generate_key(sensitive_data.private_key, public_key, | |
826 | options.server_key_bits); | |
827 | arc4random_stir(); | |
828 | log("RSA key generation complete."); | |
5260325f | 829 | |
a306f2dd | 830 | /* Schedule server key regeneration alarm. */ |
831 | signal(SIGALRM, key_regeneration_alarm); | |
832 | alarm(options.key_regeneration_time); | |
833 | } | |
5260325f | 834 | |
835 | /* Arrange to restart on SIGHUP. The handler needs listen_sock. */ | |
836 | signal(SIGHUP, sighup_handler); | |
089fbbd2 | 837 | |
5260325f | 838 | signal(SIGTERM, sigterm_handler); |
839 | signal(SIGQUIT, sigterm_handler); | |
840 | ||
841 | /* Arrange SIGCHLD to be caught. */ | |
842 | signal(SIGCHLD, main_sigchld_handler); | |
843 | ||
48e671d5 | 844 | /* setup fd set for listen */ |
089fbbd2 | 845 | fdset = NULL; |
48e671d5 | 846 | maxfd = 0; |
847 | for (i = 0; i < num_listen_socks; i++) | |
848 | if (listen_socks[i] > maxfd) | |
849 | maxfd = listen_socks[i]; | |
089fbbd2 | 850 | /* pipes connected to unauthenticated childs */ |
851 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
852 | for (i = 0; i < options.max_startups; i++) | |
853 | startup_pipes[i] = -1; | |
48e671d5 | 854 | |
aa3378df | 855 | /* |
856 | * Stay listening for connections until the system crashes or | |
857 | * the daemon is killed with a signal. | |
858 | */ | |
5260325f | 859 | for (;;) { |
860 | if (received_sighup) | |
861 | sighup_restart(); | |
089fbbd2 | 862 | if (fdset != NULL) |
863 | xfree(fdset); | |
864 | fdsetsz = howmany(maxfd, NFDBITS) * sizeof(fd_mask); | |
865 | fdset = (fd_set *)xmalloc(fdsetsz); | |
48e671d5 | 866 | memset(fdset, 0, fdsetsz); |
089fbbd2 | 867 | |
48e671d5 | 868 | for (i = 0; i < num_listen_socks; i++) |
869 | FD_SET(listen_socks[i], fdset); | |
089fbbd2 | 870 | for (i = 0; i < options.max_startups; i++) |
871 | if (startup_pipes[i] != -1) | |
872 | FD_SET(startup_pipes[i], fdset); | |
873 | ||
874 | /* Wait in select until there is a connection. */ | |
48e671d5 | 875 | if (select(maxfd + 1, fdset, NULL, NULL, NULL) < 0) { |
876 | if (errno != EINTR) | |
877 | error("select: %.100s", strerror(errno)); | |
2d86a6cc | 878 | continue; |
48e671d5 | 879 | } |
089fbbd2 | 880 | for (i = 0; i < options.max_startups; i++) |
881 | if (startup_pipes[i] != -1 && | |
882 | FD_ISSET(startup_pipes[i], fdset)) { | |
883 | /* | |
884 | * the read end of the pipe is ready | |
885 | * if the child has closed the pipe | |
886 | * after successfull authentication | |
887 | * or if the child has died | |
888 | */ | |
889 | close(startup_pipes[i]); | |
890 | startup_pipes[i] = -1; | |
891 | startups--; | |
892 | } | |
48e671d5 | 893 | for (i = 0; i < num_listen_socks; i++) { |
894 | if (!FD_ISSET(listen_socks[i], fdset)) | |
5260325f | 895 | continue; |
089fbbd2 | 896 | fromlen = sizeof(from); |
897 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
898 | &fromlen); | |
899 | if (newsock < 0) { | |
900 | if (errno != EINTR && errno != EWOULDBLOCK) | |
901 | error("accept: %.100s", strerror(errno)); | |
902 | continue; | |
903 | } | |
904 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
905 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
906 | continue; | |
907 | } | |
c345cf9d | 908 | if (drop_connection(startups) == 1) { |
909 | debug("drop connection #%d", startups); | |
089fbbd2 | 910 | close(newsock); |
911 | continue; | |
912 | } | |
913 | if (pipe(startup_p) == -1) { | |
914 | close(newsock); | |
915 | continue; | |
916 | } | |
917 | ||
918 | for (j = 0; j < options.max_startups; j++) | |
919 | if (startup_pipes[j] == -1) { | |
920 | startup_pipes[j] = startup_p[0]; | |
921 | if (maxfd < startup_p[0]) | |
922 | maxfd = startup_p[0]; | |
923 | startups++; | |
924 | break; | |
925 | } | |
926 | ||
aa3378df | 927 | /* |
089fbbd2 | 928 | * Got connection. Fork a child to handle it, unless |
929 | * we are in debugging mode. | |
aa3378df | 930 | */ |
089fbbd2 | 931 | if (debug_flag) { |
aa3378df | 932 | /* |
089fbbd2 | 933 | * In debugging mode. Close the listening |
934 | * socket, and start processing the | |
935 | * connection without forking. | |
aa3378df | 936 | */ |
089fbbd2 | 937 | debug("Server will not fork when running in debugging mode."); |
48e671d5 | 938 | close_listen_socks(); |
5260325f | 939 | sock_in = newsock; |
940 | sock_out = newsock; | |
5540ea9b | 941 | startup_pipe = -1; |
3f7a7e4a | 942 | pid = getpid(); |
5260325f | 943 | break; |
089fbbd2 | 944 | } else { |
945 | /* | |
946 | * Normal production daemon. Fork, and have | |
947 | * the child process the connection. The | |
948 | * parent continues listening. | |
949 | */ | |
950 | if ((pid = fork()) == 0) { | |
951 | /* | |
952 | * Child. Close the listening and max_startup | |
953 | * sockets. Start using the accepted socket. | |
954 | * Reinitialize logging (since our pid has | |
955 | * changed). We break out of the loop to handle | |
956 | * the connection. | |
957 | */ | |
958 | startup_pipe = startup_p[1]; | |
959 | for (j = 0; j < options.max_startups; j++) | |
960 | if (startup_pipes[j] != -1) | |
961 | close(startup_pipes[j]); | |
962 | close_listen_socks(); | |
963 | sock_in = newsock; | |
964 | sock_out = newsock; | |
965 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
966 | break; | |
967 | } | |
5260325f | 968 | } |
5260325f | 969 | |
089fbbd2 | 970 | /* Parent. Stay in the loop. */ |
971 | if (pid < 0) | |
972 | error("fork: %.100s", strerror(errno)); | |
973 | else | |
974 | debug("Forked child %d.", pid); | |
5260325f | 975 | |
089fbbd2 | 976 | close(startup_p[1]); |
5260325f | 977 | |
089fbbd2 | 978 | /* Mark that the key has been used (it was "given" to the child). */ |
979 | key_used = 1; | |
5260325f | 980 | |
089fbbd2 | 981 | arc4random_stir(); |
982 | ||
983 | /* Close the new socket (the child is now taking care of it). */ | |
984 | close(newsock); | |
985 | } | |
48e671d5 | 986 | /* child process check (or debug mode) */ |
987 | if (num_listen_socks < 0) | |
988 | break; | |
5260325f | 989 | } |
990 | } | |
8efc0c15 | 991 | |
5260325f | 992 | /* This is the child processing a new connection. */ |
993 | ||
aa3378df | 994 | /* |
995 | * Disable the key regeneration alarm. We will not regenerate the | |
996 | * key since we are no longer in a position to give it to anyone. We | |
997 | * will not restart on SIGHUP since it no longer makes sense. | |
998 | */ | |
5260325f | 999 | alarm(0); |
1000 | signal(SIGALRM, SIG_DFL); | |
1001 | signal(SIGHUP, SIG_DFL); | |
1002 | signal(SIGTERM, SIG_DFL); | |
1003 | signal(SIGQUIT, SIG_DFL); | |
1004 | signal(SIGCHLD, SIG_DFL); | |
9aaf9be4 | 1005 | signal(SIGINT, SIG_DFL); |
5260325f | 1006 | |
aa3378df | 1007 | /* |
1008 | * Set socket options for the connection. We want the socket to | |
1009 | * close as fast as possible without waiting for anything. If the | |
1010 | * connection is not a socket, these will do nothing. | |
1011 | */ | |
1012 | /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 1013 | linger.l_onoff = 1; |
1014 | linger.l_linger = 5; | |
1015 | setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
1016 | ||
aa3378df | 1017 | /* |
1018 | * Register our connection. This turns encryption off because we do | |
1019 | * not have a key. | |
1020 | */ | |
5260325f | 1021 | packet_set_connection(sock_in, sock_out); |
1022 | ||
1023 | remote_port = get_remote_port(); | |
1024 | remote_ip = get_remote_ipaddr(); | |
1025 | ||
1026 | /* Check whether logins are denied from this host. */ | |
1027 | #ifdef LIBWRAP | |
48e671d5 | 1028 | /* XXX LIBWRAP noes not know about IPv6 */ |
5260325f | 1029 | { |
1030 | struct request_info req; | |
8efc0c15 | 1031 | |
5260325f | 1032 | request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL); |
1033 | fromhost(&req); | |
8efc0c15 | 1034 | |
5260325f | 1035 | if (!hosts_access(&req)) { |
1036 | close(sock_in); | |
1037 | close(sock_out); | |
1038 | refuse(&req); | |
1039 | } | |
48e671d5 | 1040 | /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */ |
8efc0c15 | 1041 | } |
48e671d5 | 1042 | #endif /* LIBWRAP */ |
5260325f | 1043 | /* Log the connection. */ |
1044 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
8efc0c15 | 1045 | |
aa3378df | 1046 | /* |
1047 | * We don\'t want to listen forever unless the other side | |
1048 | * successfully authenticates itself. So we set up an alarm which is | |
1049 | * cleared after successful authentication. A limit of zero | |
1050 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1051 | * mode; it is just annoying to have the server exit just when you | |
1052 | * are about to discover the bug. | |
1053 | */ | |
5260325f | 1054 | signal(SIGALRM, grace_alarm_handler); |
1055 | if (!debug_flag) | |
1056 | alarm(options.login_grace_time); | |
1057 | ||
7368a6c8 | 1058 | sshd_exchange_identification(sock_in, sock_out); |
aa3378df | 1059 | /* |
1060 | * Check that the connection comes from a privileged port. Rhosts- | |
1061 | * and Rhosts-RSA-Authentication only make sense from priviledged | |
1062 | * programs. Of course, if the intruder has root access on his local | |
1063 | * machine, he can connect from any port. So do not use these | |
1064 | * authentication methods from machines that you do not trust. | |
1065 | */ | |
5260325f | 1066 | if (remote_port >= IPPORT_RESERVED || |
1067 | remote_port < IPPORT_RESERVED / 2) { | |
1068 | options.rhosts_authentication = 0; | |
1069 | options.rhosts_rsa_authentication = 0; | |
1070 | } | |
48e671d5 | 1071 | #ifdef KRB4 |
1072 | if (!packet_connection_is_ipv4() && | |
1073 | options.kerberos_authentication) { | |
1074 | debug("Kerberos Authentication disabled, only available for IPv4."); | |
1075 | options.kerberos_authentication = 0; | |
1076 | } | |
1077 | #endif /* KRB4 */ | |
1078 | ||
5260325f | 1079 | packet_set_nonblocking(); |
1080 | ||
7b2ea3a1 | 1081 | /* perform the key exchange */ |
7b2ea3a1 | 1082 | /* authenticate user and start session */ |
e78a59f5 | 1083 | if (compat20) { |
1084 | do_ssh2_kex(); | |
1085 | do_authentication2(); | |
1086 | } else { | |
1087 | do_ssh1_kex(); | |
1088 | do_authentication(); | |
1089 | } | |
8efc0c15 | 1090 | |
1091 | #ifdef KRB4 | |
5260325f | 1092 | /* Cleanup user's ticket cache file. */ |
1093 | if (options.kerberos_ticket_cleanup) | |
1094 | (void) dest_tkt(); | |
8efc0c15 | 1095 | #endif /* KRB4 */ |
1096 | ||
5260325f | 1097 | /* The connection has been terminated. */ |
1098 | verbose("Closing connection to %.100s", remote_ip); | |
8efc0c15 | 1099 | |
d94aa2ae | 1100 | #ifdef USE_PAM |
a5c9cd31 | 1101 | finish_pam(); |
d94aa2ae | 1102 | #endif /* USE_PAM */ |
8efc0c15 | 1103 | |
5260325f | 1104 | packet_close(); |
1105 | exit(0); | |
1106 | } | |
8efc0c15 | 1107 | |
5260325f | 1108 | /* |
7b2ea3a1 | 1109 | * SSH1 key exchange |
5260325f | 1110 | */ |
e7c0f9d5 | 1111 | void |
7368a6c8 | 1112 | do_ssh1_kex() |
8efc0c15 | 1113 | { |
5260325f | 1114 | int i, len; |
7b2ea3a1 | 1115 | int plen, slen; |
5260325f | 1116 | BIGNUM *session_key_int; |
1117 | unsigned char session_key[SSH_SESSION_KEY_LENGTH]; | |
7b2ea3a1 | 1118 | unsigned char cookie[8]; |
5260325f | 1119 | unsigned int cipher_type, auth_mask, protocol_flags; |
5260325f | 1120 | u_int32_t rand = 0; |
1121 | ||
aa3378df | 1122 | /* |
1123 | * Generate check bytes that the client must send back in the user | |
1124 | * packet in order for it to be accepted; this is used to defy ip | |
1125 | * spoofing attacks. Note that this only works against somebody | |
1126 | * doing IP spoofing from a remote machine; any machine on the local | |
1127 | * network can still see outgoing packets and catch the random | |
1128 | * cookie. This only affects rhosts authentication, and this is one | |
1129 | * of the reasons why it is inherently insecure. | |
1130 | */ | |
5260325f | 1131 | for (i = 0; i < 8; i++) { |
1132 | if (i % 4 == 0) | |
1133 | rand = arc4random(); | |
7b2ea3a1 | 1134 | cookie[i] = rand & 0xff; |
5260325f | 1135 | rand >>= 8; |
1136 | } | |
1137 | ||
aa3378df | 1138 | /* |
1139 | * Send our public key. We include in the packet 64 bits of random | |
1140 | * data that must be matched in the reply in order to prevent IP | |
1141 | * spoofing. | |
1142 | */ | |
5260325f | 1143 | packet_start(SSH_SMSG_PUBLIC_KEY); |
1144 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1145 | packet_put_char(cookie[i]); |
5260325f | 1146 | |
1147 | /* Store our public server RSA key. */ | |
1148 | packet_put_int(BN_num_bits(public_key->n)); | |
1149 | packet_put_bignum(public_key->e); | |
1150 | packet_put_bignum(public_key->n); | |
1151 | ||
1152 | /* Store our public host RSA key. */ | |
1153 | packet_put_int(BN_num_bits(sensitive_data.host_key->n)); | |
1154 | packet_put_bignum(sensitive_data.host_key->e); | |
1155 | packet_put_bignum(sensitive_data.host_key->n); | |
1156 | ||
1157 | /* Put protocol flags. */ | |
1158 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1159 | ||
1160 | /* Declare which ciphers we support. */ | |
94ec8c6b | 1161 | packet_put_int(cipher_mask_ssh1(0)); |
5260325f | 1162 | |
1163 | /* Declare supported authentication types. */ | |
1164 | auth_mask = 0; | |
1165 | if (options.rhosts_authentication) | |
1166 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
1167 | if (options.rhosts_rsa_authentication) | |
1168 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1169 | if (options.rsa_authentication) | |
1170 | auth_mask |= 1 << SSH_AUTH_RSA; | |
8efc0c15 | 1171 | #ifdef KRB4 |
5260325f | 1172 | if (options.kerberos_authentication) |
1173 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
8efc0c15 | 1174 | #endif |
1175 | #ifdef AFS | |
5260325f | 1176 | if (options.kerberos_tgt_passing) |
1177 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
1178 | if (options.afs_token_passing) | |
1179 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
8efc0c15 | 1180 | #endif |
5260325f | 1181 | #ifdef SKEY |
1182 | if (options.skey_authentication == 1) | |
1183 | auth_mask |= 1 << SSH_AUTH_TIS; | |
1184 | #endif | |
1185 | if (options.password_authentication) | |
1186 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1187 | packet_put_int(auth_mask); | |
1188 | ||
1189 | /* Send the packet and wait for it to be sent. */ | |
1190 | packet_send(); | |
1191 | packet_write_wait(); | |
1192 | ||
1193 | debug("Sent %d bit public key and %d bit host key.", | |
1194 | BN_num_bits(public_key->n), BN_num_bits(sensitive_data.host_key->n)); | |
1195 | ||
1196 | /* Read clients reply (cipher type and session key). */ | |
1197 | packet_read_expect(&plen, SSH_CMSG_SESSION_KEY); | |
1198 | ||
2d86a6cc | 1199 | /* Get cipher type and check whether we accept this. */ |
5260325f | 1200 | cipher_type = packet_get_char(); |
1201 | ||
94ec8c6b | 1202 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) |
2d86a6cc | 1203 | packet_disconnect("Warning: client selects unsupported cipher."); |
1204 | ||
5260325f | 1205 | /* Get check bytes from the packet. These must match those we |
1206 | sent earlier with the public key packet. */ | |
1207 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1208 | if (cookie[i] != packet_get_char()) |
5260325f | 1209 | packet_disconnect("IP Spoofing check bytes do not match."); |
1210 | ||
1211 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1212 | ||
1213 | /* Get the encrypted integer. */ | |
1214 | session_key_int = BN_new(); | |
1215 | packet_get_bignum(session_key_int, &slen); | |
1216 | ||
5260325f | 1217 | protocol_flags = packet_get_int(); |
1218 | packet_set_protocol_flags(protocol_flags); | |
1219 | ||
1220 | packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY); | |
1221 | ||
aa3378df | 1222 | /* |
1223 | * Decrypt it using our private server key and private host key (key | |
1224 | * with larger modulus first). | |
1225 | */ | |
5260325f | 1226 | if (BN_cmp(sensitive_data.private_key->n, sensitive_data.host_key->n) > 0) { |
1227 | /* Private key has bigger modulus. */ | |
1228 | if (BN_num_bits(sensitive_data.private_key->n) < | |
1229 | BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) { | |
1230 | fatal("do_connection: %s: private_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1231 | get_remote_ipaddr(), | |
1232 | BN_num_bits(sensitive_data.private_key->n), | |
1233 | BN_num_bits(sensitive_data.host_key->n), | |
1234 | SSH_KEY_BITS_RESERVED); | |
1235 | } | |
1236 | rsa_private_decrypt(session_key_int, session_key_int, | |
1237 | sensitive_data.private_key); | |
1238 | rsa_private_decrypt(session_key_int, session_key_int, | |
1239 | sensitive_data.host_key); | |
1240 | } else { | |
1241 | /* Host key has bigger modulus (or they are equal). */ | |
1242 | if (BN_num_bits(sensitive_data.host_key->n) < | |
1243 | BN_num_bits(sensitive_data.private_key->n) + SSH_KEY_BITS_RESERVED) { | |
1244 | fatal("do_connection: %s: host_key %d < private_key %d + SSH_KEY_BITS_RESERVED %d", | |
1245 | get_remote_ipaddr(), | |
1246 | BN_num_bits(sensitive_data.host_key->n), | |
1247 | BN_num_bits(sensitive_data.private_key->n), | |
1248 | SSH_KEY_BITS_RESERVED); | |
1249 | } | |
1250 | rsa_private_decrypt(session_key_int, session_key_int, | |
1251 | sensitive_data.host_key); | |
1252 | rsa_private_decrypt(session_key_int, session_key_int, | |
1253 | sensitive_data.private_key); | |
1254 | } | |
1255 | ||
7b2ea3a1 | 1256 | compute_session_id(session_id, cookie, |
5260325f | 1257 | sensitive_data.host_key->n, |
1258 | sensitive_data.private_key->n); | |
1259 | ||
7b2ea3a1 | 1260 | /* Destroy the private and public keys. They will no longer be needed. */ |
a306f2dd | 1261 | destroy_sensitive_data(); |
7b2ea3a1 | 1262 | |
aa3378df | 1263 | /* |
1264 | * Extract session key from the decrypted integer. The key is in the | |
1265 | * least significant 256 bits of the integer; the first byte of the | |
1266 | * key is in the highest bits. | |
1267 | */ | |
5260325f | 1268 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); |
1269 | len = BN_num_bytes(session_key_int); | |
1270 | if (len < 0 || len > sizeof(session_key)) | |
1271 | fatal("do_connection: bad len from %s: session_key_int %d > sizeof(session_key) %d", | |
1272 | get_remote_ipaddr(), | |
c73b8e3a | 1273 | len, (int) sizeof(session_key)); |
5260325f | 1274 | memset(session_key, 0, sizeof(session_key)); |
1275 | BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len); | |
1276 | ||
7b2ea3a1 | 1277 | /* Destroy the decrypted integer. It is no longer needed. */ |
1278 | BN_clear_free(session_key_int); | |
1279 | ||
5260325f | 1280 | /* Xor the first 16 bytes of the session key with the session id. */ |
1281 | for (i = 0; i < 16; i++) | |
1282 | session_key[i] ^= session_id[i]; | |
1283 | ||
5260325f | 1284 | /* Set the session key. From this on all communications will be encrypted. */ |
1285 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1286 | ||
1287 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1288 | memset(session_key, 0, sizeof(session_key)); | |
1289 | ||
1290 | debug("Received session key; encryption turned on."); | |
1291 | ||
1292 | /* Send an acknowledgement packet. Note that this packet is sent encrypted. */ | |
1293 | packet_start(SSH_SMSG_SUCCESS); | |
1294 | packet_send(); | |
1295 | packet_write_wait(); | |
5260325f | 1296 | } |
e78a59f5 | 1297 | |
1298 | /* | |
1299 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1300 | */ | |
1301 | void | |
1302 | do_ssh2_kex() | |
1303 | { | |
1304 | Buffer *server_kexinit; | |
1305 | Buffer *client_kexinit; | |
94ec8c6b | 1306 | int payload_len; |
e78a59f5 | 1307 | int i; |
e78a59f5 | 1308 | Kex *kex; |
e78a59f5 | 1309 | char *cprop[PROPOSAL_MAX]; |
e78a59f5 | 1310 | |
1311 | /* KEXINIT */ | |
1312 | ||
a8be9f80 | 1313 | if (options.ciphers != NULL) { |
6ae2364d | 1314 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
a8be9f80 | 1315 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
1316 | } | |
71276795 | 1317 | server_kexinit = kex_init(myproposal); |
e78a59f5 | 1318 | client_kexinit = xmalloc(sizeof(*client_kexinit)); |
1319 | buffer_init(client_kexinit); | |
e78a59f5 | 1320 | |
71276795 | 1321 | /* algorithm negotiation */ |
1322 | kex_exchange_kexinit(server_kexinit, client_kexinit, cprop); | |
1323 | kex = kex_choose_conf(cprop, myproposal, 1); | |
1324 | for (i = 0; i < PROPOSAL_MAX; i++) | |
1325 | xfree(cprop[i]); | |
e78a59f5 | 1326 | |
94ec8c6b | 1327 | switch (kex->kex_type) { |
1328 | case DH_GRP1_SHA1: | |
1329 | ssh_dh1_server(kex, client_kexinit, server_kexinit); | |
1330 | break; | |
1331 | case DH_GEX_SHA1: | |
1332 | ssh_dhgex_server(kex, client_kexinit, server_kexinit); | |
1333 | break; | |
1334 | default: | |
1335 | fatal("Unsupported key exchange %d", kex->kex_type); | |
1336 | } | |
1337 | ||
1338 | debug("send SSH2_MSG_NEWKEYS."); | |
1339 | packet_start(SSH2_MSG_NEWKEYS); | |
1340 | packet_send(); | |
1341 | packet_write_wait(); | |
1342 | debug("done: send SSH2_MSG_NEWKEYS."); | |
1343 | ||
1344 | debug("Wait SSH2_MSG_NEWKEYS."); | |
1345 | packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS); | |
1346 | debug("GOT SSH2_MSG_NEWKEYS."); | |
1347 | ||
1348 | #ifdef DEBUG_KEXDH | |
1349 | /* send 1st encrypted/maced/compressed message */ | |
1350 | packet_start(SSH2_MSG_IGNORE); | |
1351 | packet_put_cstring("markus"); | |
1352 | packet_send(); | |
1353 | packet_write_wait(); | |
1354 | #endif | |
1355 | ||
1356 | debug("done: KEX2."); | |
1357 | } | |
1358 | ||
1359 | /* | |
1360 | * SSH2 key exchange | |
1361 | */ | |
1362 | ||
1363 | /* diffie-hellman-group1-sha1 */ | |
1364 | ||
1365 | void | |
1366 | ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit) | |
1367 | { | |
1368 | #ifdef DEBUG_KEXDH | |
1369 | int i; | |
1370 | #endif | |
1371 | int payload_len, dlen; | |
1372 | int slen; | |
1373 | unsigned char *signature = NULL; | |
1374 | unsigned char *server_host_key_blob = NULL; | |
1375 | unsigned int sbloblen; | |
1376 | unsigned int klen, kout; | |
1377 | unsigned char *kbuf; | |
1378 | unsigned char *hash; | |
1379 | BIGNUM *shared_secret = 0; | |
1380 | DH *dh; | |
1381 | BIGNUM *dh_client_pub = 0; | |
e78a59f5 | 1382 | |
94ec8c6b | 1383 | /* KEXDH */ |
e78a59f5 | 1384 | debug("Wait SSH2_MSG_KEXDH_INIT."); |
1385 | packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT); | |
1386 | ||
1387 | /* key, cert */ | |
1388 | dh_client_pub = BN_new(); | |
1389 | if (dh_client_pub == NULL) | |
1390 | fatal("dh_client_pub == NULL"); | |
1391 | packet_get_bignum2(dh_client_pub, &dlen); | |
1392 | ||
1393 | #ifdef DEBUG_KEXDH | |
1394 | fprintf(stderr, "\ndh_client_pub= "); | |
188adeb2 | 1395 | BN_print_fp(stderr, dh_client_pub); |
e78a59f5 | 1396 | fprintf(stderr, "\n"); |
1397 | debug("bits %d", BN_num_bits(dh_client_pub)); | |
1398 | #endif | |
1399 | ||
1400 | /* generate DH key */ | |
a8be9f80 | 1401 | dh = dh_new_group1(); /* XXX depends on 'kex' */ |
e78a59f5 | 1402 | |
1403 | #ifdef DEBUG_KEXDH | |
1404 | fprintf(stderr, "\np= "); | |
188adeb2 | 1405 | BN_print_fp(stderr, dh->p); |
e78a59f5 | 1406 | fprintf(stderr, "\ng= "); |
188adeb2 | 1407 | bn_print(dh->g); |
e78a59f5 | 1408 | fprintf(stderr, "\npub= "); |
188adeb2 | 1409 | BN_print_fp(stderr, dh->pub_key); |
e78a59f5 | 1410 | fprintf(stderr, "\n"); |
188adeb2 | 1411 | DHparams_print_fp(stderr, dh); |
e78a59f5 | 1412 | #endif |
a8be9f80 | 1413 | if (!dh_pub_is_valid(dh, dh_client_pub)) |
1414 | packet_disconnect("bad client public DH value"); | |
e78a59f5 | 1415 | |
1416 | klen = DH_size(dh); | |
1417 | kbuf = xmalloc(klen); | |
1418 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | |
1419 | ||
1420 | #ifdef DEBUG_KEXDH | |
1421 | debug("shared secret: len %d/%d", klen, kout); | |
1422 | fprintf(stderr, "shared secret == "); | |
1423 | for (i = 0; i< kout; i++) | |
1424 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
1425 | fprintf(stderr, "\n"); | |
1426 | #endif | |
1427 | shared_secret = BN_new(); | |
1428 | ||
1429 | BN_bin2bn(kbuf, kout, shared_secret); | |
1430 | memset(kbuf, 0, klen); | |
1431 | xfree(kbuf); | |
1432 | ||
a306f2dd | 1433 | /* XXX precompute? */ |
94ec8c6b | 1434 | dsa_make_key_blob(sensitive_data.dsa_host_key, |
1435 | &server_host_key_blob, &sbloblen); | |
e78a59f5 | 1436 | |
1437 | /* calc H */ /* XXX depends on 'kex' */ | |
1438 | hash = kex_hash( | |
1439 | client_version_string, | |
1440 | server_version_string, | |
1441 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
1442 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
1443 | (char *)server_host_key_blob, sbloblen, | |
1444 | dh_client_pub, | |
1445 | dh->pub_key, | |
1446 | shared_secret | |
1447 | ); | |
1448 | buffer_free(client_kexinit); | |
1449 | buffer_free(server_kexinit); | |
1450 | xfree(client_kexinit); | |
1451 | xfree(server_kexinit); | |
1452 | #ifdef DEBUG_KEXDH | |
6ae2364d | 1453 | fprintf(stderr, "hash == "); |
1454 | for (i = 0; i< 20; i++) | |
1455 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
1456 | fprintf(stderr, "\n"); | |
e78a59f5 | 1457 | #endif |
a306f2dd | 1458 | /* save session id := H */ |
1459 | /* XXX hashlen depends on KEX */ | |
1460 | session_id2_len = 20; | |
1461 | session_id2 = xmalloc(session_id2_len); | |
1462 | memcpy(session_id2, hash, session_id2_len); | |
1463 | ||
e78a59f5 | 1464 | /* sign H */ |
a306f2dd | 1465 | /* XXX hashlen depends on KEX */ |
1466 | dsa_sign(sensitive_data.dsa_host_key, &signature, &slen, hash, 20); | |
1467 | ||
1468 | destroy_sensitive_data(); | |
e78a59f5 | 1469 | |
1470 | /* send server hostkey, DH pubkey 'f' and singed H */ | |
1471 | packet_start(SSH2_MSG_KEXDH_REPLY); | |
1472 | packet_put_string((char *)server_host_key_blob, sbloblen); | |
1d1ffb87 | 1473 | packet_put_bignum2(dh->pub_key); /* f */ |
e78a59f5 | 1474 | packet_put_string((char *)signature, slen); |
1475 | packet_send(); | |
d6f24e45 | 1476 | xfree(signature); |
a306f2dd | 1477 | xfree(server_host_key_blob); |
e78a59f5 | 1478 | packet_write_wait(); |
1479 | ||
1480 | kex_derive_keys(kex, hash, shared_secret); | |
1481 | packet_set_kex(kex); | |
1482 | ||
1483 | /* have keys, free DH */ | |
1484 | DH_free(dh); | |
94ec8c6b | 1485 | } |
e78a59f5 | 1486 | |
94ec8c6b | 1487 | /* diffie-hellman-group-exchange-sha1 */ |
1488 | ||
1489 | void | |
1490 | ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit) | |
1491 | { | |
1492 | #ifdef DEBUG_KEXDH | |
1493 | int i; | |
1494 | #endif | |
1495 | int payload_len, dlen; | |
1496 | int slen, nbits; | |
1497 | unsigned char *signature = NULL; | |
1498 | unsigned char *server_host_key_blob = NULL; | |
1499 | unsigned int sbloblen; | |
1500 | unsigned int klen, kout; | |
1501 | unsigned char *kbuf; | |
1502 | unsigned char *hash; | |
1503 | BIGNUM *shared_secret = 0; | |
1504 | DH *dh; | |
1505 | BIGNUM *dh_client_pub = 0; | |
1506 | ||
1507 | /* KEXDHGEX */ | |
1508 | debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST."); | |
1509 | packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_REQUEST); | |
1510 | nbits = packet_get_int(); | |
1511 | dh = choose_dh(nbits); | |
1512 | ||
1513 | debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP."); | |
1514 | packet_start(SSH2_MSG_KEX_DH_GEX_GROUP); | |
1515 | packet_put_bignum2(dh->p); | |
1516 | packet_put_bignum2(dh->g); | |
e78a59f5 | 1517 | packet_send(); |
1518 | packet_write_wait(); | |
e78a59f5 | 1519 | |
94ec8c6b | 1520 | debug("Wait SSH2_MSG_KEX_DH_GEX_INIT."); |
1521 | packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_INIT); | |
1522 | ||
1523 | /* key, cert */ | |
1524 | dh_client_pub = BN_new(); | |
1525 | if (dh_client_pub == NULL) | |
1526 | fatal("dh_client_pub == NULL"); | |
1527 | packet_get_bignum2(dh_client_pub, &dlen); | |
e78a59f5 | 1528 | |
a8be9f80 | 1529 | #ifdef DEBUG_KEXDH |
94ec8c6b | 1530 | fprintf(stderr, "\ndh_client_pub= "); |
1531 | BN_print_fp(stderr, dh_client_pub); | |
1532 | fprintf(stderr, "\n"); | |
1533 | debug("bits %d", BN_num_bits(dh_client_pub)); | |
1534 | #endif | |
1535 | ||
1536 | #ifdef DEBUG_KEXDH | |
1537 | fprintf(stderr, "\np= "); | |
1538 | BN_print_fp(stderr, dh->p); | |
1539 | fprintf(stderr, "\ng= "); | |
1540 | bn_print(dh->g); | |
1541 | fprintf(stderr, "\npub= "); | |
1542 | BN_print_fp(stderr, dh->pub_key); | |
1543 | fprintf(stderr, "\n"); | |
1544 | DHparams_print_fp(stderr, dh); | |
1545 | #endif | |
1546 | if (!dh_pub_is_valid(dh, dh_client_pub)) | |
1547 | packet_disconnect("bad client public DH value"); | |
1548 | ||
1549 | klen = DH_size(dh); | |
1550 | kbuf = xmalloc(klen); | |
1551 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | |
1552 | ||
1553 | #ifdef DEBUG_KEXDH | |
1554 | debug("shared secret: len %d/%d", klen, kout); | |
1555 | fprintf(stderr, "shared secret == "); | |
1556 | for (i = 0; i< kout; i++) | |
1557 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
1558 | fprintf(stderr, "\n"); | |
1559 | #endif | |
1560 | shared_secret = BN_new(); | |
1561 | ||
1562 | BN_bin2bn(kbuf, kout, shared_secret); | |
1563 | memset(kbuf, 0, klen); | |
1564 | xfree(kbuf); | |
1565 | ||
1566 | /* XXX precompute? */ | |
1567 | dsa_make_key_blob(sensitive_data.dsa_host_key, | |
1568 | &server_host_key_blob, &sbloblen); | |
1569 | ||
1570 | /* calc H */ /* XXX depends on 'kex' */ | |
1571 | hash = kex_hash_gex( | |
1572 | client_version_string, | |
1573 | server_version_string, | |
1574 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
1575 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
1576 | (char *)server_host_key_blob, sbloblen, | |
1577 | nbits, dh->p, dh->g, | |
1578 | dh_client_pub, | |
1579 | dh->pub_key, | |
1580 | shared_secret | |
1581 | ); | |
1582 | buffer_free(client_kexinit); | |
1583 | buffer_free(server_kexinit); | |
1584 | xfree(client_kexinit); | |
1585 | xfree(server_kexinit); | |
1586 | #ifdef DEBUG_KEXDH | |
1587 | fprintf(stderr, "hash == "); | |
1588 | for (i = 0; i< 20; i++) | |
1589 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
1590 | fprintf(stderr, "\n"); | |
1591 | #endif | |
1592 | /* save session id := H */ | |
1593 | /* XXX hashlen depends on KEX */ | |
1594 | session_id2_len = 20; | |
1595 | session_id2 = xmalloc(session_id2_len); | |
1596 | memcpy(session_id2, hash, session_id2_len); | |
1597 | ||
1598 | /* sign H */ | |
1599 | /* XXX hashlen depends on KEX */ | |
1600 | dsa_sign(sensitive_data.dsa_host_key, &signature, &slen, hash, 20); | |
1601 | ||
1602 | destroy_sensitive_data(); | |
1603 | ||
1604 | /* send server hostkey, DH pubkey 'f' and singed H */ | |
1605 | packet_start(SSH2_MSG_KEX_DH_GEX_REPLY); | |
1606 | packet_put_string((char *)server_host_key_blob, sbloblen); | |
1607 | packet_put_bignum2(dh->pub_key); /* f */ | |
1608 | packet_put_string((char *)signature, slen); | |
e78a59f5 | 1609 | packet_send(); |
94ec8c6b | 1610 | xfree(signature); |
1611 | xfree(server_host_key_blob); | |
e78a59f5 | 1612 | packet_write_wait(); |
94ec8c6b | 1613 | |
1614 | kex_derive_keys(kex, hash, shared_secret); | |
1615 | packet_set_kex(kex); | |
1616 | ||
1617 | /* have keys, free DH */ | |
1618 | DH_free(dh); | |
e78a59f5 | 1619 | } |
94ec8c6b | 1620 |