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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 | |
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" | |
fa08c86b | 43 | RCSID("$OpenBSD: sshd.c,v 1.134 2000/11/12 19:50:38 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" |
94ec8c6b | 64 | #include "dh.h" |
7368a6c8 | 65 | |
66 | #include "auth.h" | |
e78a59f5 | 67 | #include "myproposal.h" |
a306f2dd | 68 | #include "authfile.h" |
8efc0c15 | 69 | |
70 | #ifdef LIBWRAP | |
71 | #include <tcpd.h> | |
72 | #include <syslog.h> | |
73 | int allow_severity = LOG_INFO; | |
74 | int deny_severity = LOG_WARNING; | |
75 | #endif /* LIBWRAP */ | |
76 | ||
77 | #ifndef O_NOCTTY | |
78 | #define O_NOCTTY 0 | |
79 | #endif | |
80 | ||
8efc0c15 | 81 | /* Server configuration options. */ |
82 | ServerOptions options; | |
83 | ||
84 | /* Name of the server configuration file. */ | |
85 | char *config_file_name = SERVER_CONFIG_FILE; | |
86 | ||
6ae2364d | 87 | /* |
48e671d5 | 88 | * Flag indicating whether IPv4 or IPv6. This can be set on the command line. |
89 | * Default value is AF_UNSPEC means both IPv4 and IPv6. | |
90 | */ | |
59e76f33 | 91 | #ifdef IPV4_DEFAULT |
92 | int IPv4or6 = AF_INET; | |
93 | #else | |
48e671d5 | 94 | int IPv4or6 = AF_UNSPEC; |
59e76f33 | 95 | #endif |
48e671d5 | 96 | |
5260325f | 97 | /* |
98 | * Debug mode flag. This can be set on the command line. If debug | |
99 | * mode is enabled, extra debugging output will be sent to the system | |
100 | * log, the daemon will not go to background, and will exit after processing | |
101 | * the first connection. | |
102 | */ | |
8efc0c15 | 103 | int debug_flag = 0; |
104 | ||
105 | /* Flag indicating that the daemon is being started from inetd. */ | |
106 | int inetd_flag = 0; | |
107 | ||
6a17f9c2 | 108 | /* debug goes to stderr unless inetd_flag is set */ |
109 | int log_stderr = 0; | |
110 | ||
8efc0c15 | 111 | /* argv[0] without path. */ |
112 | char *av0; | |
113 | ||
114 | /* Saved arguments to main(). */ | |
115 | char **saved_argv; | |
4d33e531 | 116 | int saved_argc; |
8efc0c15 | 117 | |
aa3378df | 118 | /* |
48e671d5 | 119 | * The sockets that the server is listening; this is used in the SIGHUP |
120 | * signal handler. | |
aa3378df | 121 | */ |
48e671d5 | 122 | #define MAX_LISTEN_SOCKS 16 |
123 | int listen_socks[MAX_LISTEN_SOCKS]; | |
124 | int num_listen_socks = 0; | |
8efc0c15 | 125 | |
aa3378df | 126 | /* |
127 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
128 | * sshd will skip the version-number exchange | |
129 | */ | |
5260325f | 130 | char *client_version_string = NULL; |
7368a6c8 | 131 | char *server_version_string = NULL; |
8efc0c15 | 132 | |
aa3378df | 133 | /* |
134 | * Any really sensitive data in the application is contained in this | |
135 | * structure. The idea is that this structure could be locked into memory so | |
136 | * that the pages do not get written into swap. However, there are some | |
137 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
138 | * have access to the internals of them, and locking just the structure is | |
139 | * not very useful. Currently, memory locking is not implemented. | |
140 | */ | |
5260325f | 141 | struct { |
fa08c86b | 142 | Key *server_key; /* empheral server key */ |
143 | Key *ssh1_host_key; /* ssh1 host key */ | |
144 | Key **host_keys; /* all private host keys */ | |
145 | int have_ssh1_key; | |
146 | int have_ssh2_key; | |
8efc0c15 | 147 | } sensitive_data; |
148 | ||
aa3378df | 149 | /* |
150 | * Flag indicating whether the current session key has been used. This flag | |
151 | * is set whenever the key is used, and cleared when the key is regenerated. | |
152 | */ | |
8efc0c15 | 153 | int key_used = 0; |
154 | ||
155 | /* This is set to true when SIGHUP is received. */ | |
156 | int received_sighup = 0; | |
157 | ||
7368a6c8 | 158 | /* session identifier, used by RSA-auth */ |
159 | unsigned char session_id[16]; | |
e7c0f9d5 | 160 | |
a306f2dd | 161 | /* same for ssh2 */ |
162 | unsigned char *session_id2 = NULL; | |
163 | int session_id2_len = 0; | |
164 | ||
c345cf9d | 165 | /* record remote hostname or ip */ |
166 | unsigned int utmp_len = MAXHOSTNAMELEN; | |
167 | ||
7368a6c8 | 168 | /* Prototypes for various functions defined later in this file. */ |
169 | void do_ssh1_kex(); | |
e78a59f5 | 170 | void do_ssh2_kex(); |
c8d54615 | 171 | |
94ec8c6b | 172 | void ssh_dh1_server(Kex *, Buffer *_kexinit, Buffer *); |
173 | void ssh_dhgex_server(Kex *, Buffer *_kexinit, Buffer *); | |
174 | ||
48e671d5 | 175 | /* |
176 | * Close all listening sockets | |
177 | */ | |
178 | void | |
179 | close_listen_socks(void) | |
180 | { | |
181 | int i; | |
182 | for (i = 0; i < num_listen_socks; i++) | |
183 | close(listen_socks[i]); | |
184 | num_listen_socks = -1; | |
185 | } | |
186 | ||
5260325f | 187 | /* |
188 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
189 | * the effect is to reread the configuration file (and to regenerate | |
190 | * the server key). | |
191 | */ | |
6ae2364d | 192 | void |
5260325f | 193 | sighup_handler(int sig) |
8efc0c15 | 194 | { |
5260325f | 195 | received_sighup = 1; |
196 | signal(SIGHUP, sighup_handler); | |
8efc0c15 | 197 | } |
198 | ||
5260325f | 199 | /* |
200 | * Called from the main program after receiving SIGHUP. | |
201 | * Restarts the server. | |
202 | */ | |
6ae2364d | 203 | void |
5260325f | 204 | sighup_restart() |
8efc0c15 | 205 | { |
5260325f | 206 | log("Received SIGHUP; restarting."); |
48e671d5 | 207 | close_listen_socks(); |
5260325f | 208 | execv(saved_argv[0], saved_argv); |
209 | log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno)); | |
210 | exit(1); | |
8efc0c15 | 211 | } |
212 | ||
5260325f | 213 | /* |
214 | * Generic signal handler for terminating signals in the master daemon. | |
215 | * These close the listen socket; not closing it seems to cause "Address | |
216 | * already in use" problems on some machines, which is inconvenient. | |
217 | */ | |
6ae2364d | 218 | void |
5260325f | 219 | sigterm_handler(int sig) |
8efc0c15 | 220 | { |
5260325f | 221 | log("Received signal %d; terminating.", sig); |
48e671d5 | 222 | close_listen_socks(); |
0fbe8c74 | 223 | unlink(options.pid_file); |
5260325f | 224 | exit(255); |
8efc0c15 | 225 | } |
226 | ||
5260325f | 227 | /* |
228 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
229 | * reap any zombies left by exited c. | |
230 | */ | |
6ae2364d | 231 | void |
5260325f | 232 | main_sigchld_handler(int sig) |
8efc0c15 | 233 | { |
5260325f | 234 | int save_errno = errno; |
235 | int status; | |
5ad13cd7 | 236 | |
5260325f | 237 | while (waitpid(-1, &status, WNOHANG) > 0) |
238 | ; | |
5ad13cd7 | 239 | |
5260325f | 240 | signal(SIGCHLD, main_sigchld_handler); |
241 | errno = save_errno; | |
8efc0c15 | 242 | } |
243 | ||
5260325f | 244 | /* |
245 | * Signal handler for the alarm after the login grace period has expired. | |
246 | */ | |
6ae2364d | 247 | void |
5260325f | 248 | grace_alarm_handler(int sig) |
8efc0c15 | 249 | { |
5260325f | 250 | /* Close the connection. */ |
251 | packet_close(); | |
8efc0c15 | 252 | |
5260325f | 253 | /* Log error and exit. */ |
254 | fatal("Timeout before authentication for %s.", get_remote_ipaddr()); | |
255 | } | |
8efc0c15 | 256 | |
5260325f | 257 | /* |
258 | * Signal handler for the key regeneration alarm. Note that this | |
259 | * alarm only occurs in the daemon waiting for connections, and it does not | |
260 | * do anything with the private key or random state before forking. | |
261 | * Thus there should be no concurrency control/asynchronous execution | |
262 | * problems. | |
263 | */ | |
a306f2dd | 264 | /* XXX do we really want this work to be done in a signal handler ? -m */ |
6ae2364d | 265 | void |
fa08c86b | 266 | generate_empheral_server_key(void) |
267 | { | |
268 | log("Generating %s%d bit RSA key.", sensitive_data.server_key ? "new " : "", | |
269 | options.server_key_bits); | |
270 | if (sensitive_data.server_key != NULL) | |
271 | key_free(sensitive_data.server_key); | |
272 | sensitive_data.server_key = key_generate(KEY_RSA1, options.server_key_bits); | |
273 | arc4random_stir(); | |
274 | log("RSA key generation complete."); | |
275 | } | |
276 | void | |
5260325f | 277 | key_regeneration_alarm(int sig) |
278 | { | |
279 | int save_errno = errno; | |
280 | ||
281 | /* Check if we should generate a new key. */ | |
282 | if (key_used) { | |
283 | /* This should really be done in the background. */ | |
fa08c86b | 284 | generate_empheral_server_key(); |
5260325f | 285 | key_used = 0; |
5260325f | 286 | } |
287 | /* Reschedule the alarm. */ | |
288 | signal(SIGALRM, key_regeneration_alarm); | |
289 | alarm(options.key_regeneration_time); | |
290 | errno = save_errno; | |
291 | } | |
8efc0c15 | 292 | |
7368a6c8 | 293 | void |
294 | sshd_exchange_identification(int sock_in, int sock_out) | |
295 | { | |
a8be9f80 | 296 | int i, mismatch; |
7368a6c8 | 297 | int remote_major, remote_minor; |
a8be9f80 | 298 | int major, minor; |
7368a6c8 | 299 | char *s; |
300 | char buf[256]; /* Must not be larger than remote_version. */ | |
301 | char remote_version[256]; /* Must be at least as big as buf. */ | |
302 | ||
a8be9f80 | 303 | if ((options.protocol & SSH_PROTO_1) && |
304 | (options.protocol & SSH_PROTO_2)) { | |
305 | major = PROTOCOL_MAJOR_1; | |
306 | minor = 99; | |
307 | } else if (options.protocol & SSH_PROTO_2) { | |
308 | major = PROTOCOL_MAJOR_2; | |
309 | minor = PROTOCOL_MINOR_2; | |
310 | } else { | |
311 | major = PROTOCOL_MAJOR_1; | |
312 | minor = PROTOCOL_MINOR_1; | |
313 | } | |
314 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
7368a6c8 | 315 | server_version_string = xstrdup(buf); |
316 | ||
317 | if (client_version_string == NULL) { | |
318 | /* Send our protocol version identification. */ | |
319 | if (atomicio(write, sock_out, server_version_string, strlen(server_version_string)) | |
320 | != strlen(server_version_string)) { | |
321 | log("Could not write ident string to %s.", get_remote_ipaddr()); | |
322 | fatal_cleanup(); | |
323 | } | |
324 | ||
325 | /* Read other side\'s version identification. */ | |
326 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
e5a0294f | 327 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { |
7368a6c8 | 328 | log("Did not receive ident string from %s.", get_remote_ipaddr()); |
329 | fatal_cleanup(); | |
330 | } | |
331 | if (buf[i] == '\r') { | |
332 | buf[i] = '\n'; | |
333 | buf[i + 1] = 0; | |
94ec8c6b | 334 | /* Kludge for F-Secure Macintosh < 1.0.2 */ |
335 | if (i == 12 && | |
336 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
337 | break; | |
7368a6c8 | 338 | continue; |
7368a6c8 | 339 | } |
340 | if (buf[i] == '\n') { | |
341 | /* buf[i] == '\n' */ | |
342 | buf[i + 1] = 0; | |
343 | break; | |
344 | } | |
345 | } | |
346 | buf[sizeof(buf) - 1] = 0; | |
347 | client_version_string = xstrdup(buf); | |
348 | } | |
349 | ||
350 | /* | |
351 | * Check that the versions match. In future this might accept | |
352 | * several versions and set appropriate flags to handle them. | |
353 | */ | |
354 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
355 | &remote_major, &remote_minor, remote_version) != 3) { | |
6ae2364d | 356 | s = "Protocol mismatch.\n"; |
7368a6c8 | 357 | (void) atomicio(write, sock_out, s, strlen(s)); |
358 | close(sock_in); | |
359 | close(sock_out); | |
360 | log("Bad protocol version identification '%.100s' from %s", | |
361 | client_version_string, get_remote_ipaddr()); | |
362 | fatal_cleanup(); | |
363 | } | |
364 | debug("Client protocol version %d.%d; client software version %.100s", | |
365 | remote_major, remote_minor, remote_version); | |
366 | ||
e78a59f5 | 367 | compat_datafellows(remote_version); |
368 | ||
a8be9f80 | 369 | mismatch = 0; |
7368a6c8 | 370 | switch(remote_major) { |
371 | case 1: | |
a306f2dd | 372 | if (remote_minor == 99) { |
373 | if (options.protocol & SSH_PROTO_2) | |
374 | enable_compat20(); | |
375 | else | |
376 | mismatch = 1; | |
377 | break; | |
378 | } | |
a8be9f80 | 379 | if (!(options.protocol & SSH_PROTO_1)) { |
380 | mismatch = 1; | |
381 | break; | |
382 | } | |
7368a6c8 | 383 | if (remote_minor < 3) { |
089fbbd2 | 384 | packet_disconnect("Your ssh version is too old and " |
7368a6c8 | 385 | "is no longer supported. Please install a newer version."); |
386 | } else if (remote_minor == 3) { | |
387 | /* note that this disables agent-forwarding */ | |
388 | enable_compat13(); | |
389 | } | |
a8be9f80 | 390 | break; |
e78a59f5 | 391 | case 2: |
a8be9f80 | 392 | if (options.protocol & SSH_PROTO_2) { |
e78a59f5 | 393 | enable_compat20(); |
394 | break; | |
395 | } | |
396 | /* FALLTHROUGH */ | |
6ae2364d | 397 | default: |
a8be9f80 | 398 | mismatch = 1; |
399 | break; | |
400 | } | |
401 | chop(server_version_string); | |
402 | chop(client_version_string); | |
403 | debug("Local version string %.200s", server_version_string); | |
404 | ||
405 | if (mismatch) { | |
7368a6c8 | 406 | s = "Protocol major versions differ.\n"; |
407 | (void) atomicio(write, sock_out, s, strlen(s)); | |
408 | close(sock_in); | |
409 | close(sock_out); | |
a8be9f80 | 410 | log("Protocol major versions differ for %s: %.200s vs. %.200s", |
411 | get_remote_ipaddr(), | |
412 | server_version_string, client_version_string); | |
7368a6c8 | 413 | fatal_cleanup(); |
7368a6c8 | 414 | } |
a306f2dd | 415 | if (compat20) |
416 | packet_set_ssh2_format(); | |
417 | } | |
418 | ||
419 | ||
fa08c86b | 420 | /* Destroy the host and server keys. They will no longer be needed. */ |
a306f2dd | 421 | void |
422 | destroy_sensitive_data(void) | |
423 | { | |
fa08c86b | 424 | int i; |
425 | ||
426 | if (sensitive_data.server_key) { | |
427 | key_free(sensitive_data.server_key); | |
428 | sensitive_data.server_key = NULL; | |
429 | } | |
430 | for(i = 0; i < options.num_host_key_files; i++) { | |
431 | if (sensitive_data.host_keys[i]) { | |
432 | key_free(sensitive_data.host_keys[i]); | |
433 | sensitive_data.host_keys[i] = NULL; | |
434 | } | |
435 | } | |
436 | sensitive_data.ssh1_host_key = NULL; | |
437 | } | |
438 | Key * | |
439 | load_private_key_autodetect(const char *filename) | |
440 | { | |
441 | struct stat st; | |
442 | int type; | |
443 | Key *public, *private; | |
444 | ||
445 | if (stat(filename, &st) < 0) { | |
446 | perror(filename); | |
447 | return NULL; | |
448 | } | |
449 | /* | |
450 | * try to load the public key. right now this only works for RSA1, | |
451 | * since SSH2 keys are fully encrypted | |
452 | */ | |
453 | type = KEY_RSA1; | |
454 | public = key_new(type); | |
455 | if (!load_public_key(filename, public, NULL)) { | |
456 | /* ok, so we will assume this is 'some' key */ | |
457 | type = KEY_UNSPEC; | |
458 | } | |
459 | key_free(public); | |
460 | ||
461 | /* Ok, try key with empty passphrase */ | |
462 | private = key_new(type); | |
463 | if (load_private_key(filename, "", private, NULL)) { | |
464 | debug("load_private_key_autodetect: type %d %s", | |
465 | private->type, key_type(private)); | |
466 | return private; | |
467 | } | |
468 | key_free(private); | |
469 | return NULL; | |
470 | } | |
471 | ||
472 | char * | |
473 | list_hostkey_types(void) | |
474 | { | |
475 | static char buf[1024]; | |
476 | int i; | |
477 | buf[0] = '\0'; | |
478 | for(i = 0; i < options.num_host_key_files; i++) { | |
479 | Key *key = sensitive_data.host_keys[i]; | |
480 | if (key == NULL) | |
481 | continue; | |
482 | switch(key->type) { | |
483 | case KEY_RSA: | |
484 | case KEY_DSA: | |
485 | strlcat(buf, key_ssh_name(key), sizeof buf); | |
486 | strlcat(buf, ",", sizeof buf); | |
487 | break; | |
488 | } | |
489 | } | |
490 | i = strlen(buf); | |
491 | if (i > 0 && buf[i-1] == ',') | |
492 | buf[i-1] = '\0'; | |
493 | debug("list_hostkey_types: %s", buf); | |
494 | return buf; | |
495 | } | |
496 | ||
497 | Key * | |
498 | get_hostkey_by_type(int type) | |
499 | { | |
500 | int i; | |
501 | for(i = 0; i < options.num_host_key_files; i++) { | |
502 | Key *key = sensitive_data.host_keys[i]; | |
503 | if (key != NULL && key->type == type) | |
504 | return key; | |
505 | } | |
506 | return NULL; | |
7368a6c8 | 507 | } |
508 | ||
c345cf9d | 509 | /* |
510 | * returns 1 if connection should be dropped, 0 otherwise. | |
511 | * dropping starts at connection #max_startups_begin with a probability | |
512 | * of (max_startups_rate/100). the probability increases linearly until | |
513 | * all connections are dropped for startups > max_startups | |
514 | */ | |
515 | int | |
516 | drop_connection(int startups) | |
517 | { | |
518 | double p, r; | |
519 | ||
520 | if (startups < options.max_startups_begin) | |
521 | return 0; | |
522 | if (startups >= options.max_startups) | |
523 | return 1; | |
524 | if (options.max_startups_rate == 100) | |
525 | return 1; | |
526 | ||
527 | p = 100 - options.max_startups_rate; | |
528 | p *= startups - options.max_startups_begin; | |
529 | p /= (double) (options.max_startups - options.max_startups_begin); | |
530 | p += options.max_startups_rate; | |
531 | p /= 100.0; | |
532 | r = arc4random() / (double) UINT_MAX; | |
533 | ||
534 | debug("drop_connection: p %g, r %g", p, r); | |
535 | return (r < p) ? 1 : 0; | |
536 | } | |
537 | ||
089fbbd2 | 538 | int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */ |
539 | int startup_pipe; /* in child */ | |
540 | ||
5260325f | 541 | /* |
542 | * Main program for the daemon. | |
543 | */ | |
8efc0c15 | 544 | int |
545 | main(int ac, char **av) | |
546 | { | |
5260325f | 547 | extern char *optarg; |
548 | extern int optind; | |
089fbbd2 | 549 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; |
9da5c3c9 | 550 | pid_t pid; |
48e671d5 | 551 | socklen_t fromlen; |
a306f2dd | 552 | int silent = 0; |
48e671d5 | 553 | fd_set *fdset; |
554 | struct sockaddr_storage from; | |
5260325f | 555 | const char *remote_ip; |
556 | int remote_port; | |
5260325f | 557 | FILE *f; |
558 | struct linger linger; | |
48e671d5 | 559 | struct addrinfo *ai; |
560 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
561 | int listen_sock, maxfd; | |
089fbbd2 | 562 | int startup_p[2]; |
563 | int startups = 0; | |
5260325f | 564 | |
264dce47 | 565 | init_rng(); |
566 | ||
5260325f | 567 | /* Save argv[0]. */ |
4d33e531 | 568 | saved_argc = ac; |
5260325f | 569 | saved_argv = av; |
570 | if (strchr(av[0], '/')) | |
571 | av0 = strrchr(av[0], '/') + 1; | |
572 | else | |
573 | av0 = av[0]; | |
574 | ||
575 | /* Initialize configuration options to their default values. */ | |
576 | initialize_server_options(&options); | |
577 | ||
578 | /* Parse command-line arguments. */ | |
c345cf9d | 579 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:diqQ46")) != EOF) { |
5260325f | 580 | switch (opt) { |
48e671d5 | 581 | case '4': |
582 | IPv4or6 = AF_INET; | |
583 | break; | |
584 | case '6': | |
585 | IPv4or6 = AF_INET6; | |
586 | break; | |
5260325f | 587 | case 'f': |
588 | config_file_name = optarg; | |
589 | break; | |
590 | case 'd': | |
bcbf86ec | 591 | if (0 == debug_flag) { |
592 | debug_flag = 1; | |
593 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
594 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
595 | options.log_level++; | |
596 | } else { | |
597 | fprintf(stderr, "Too high debugging level.\n"); | |
598 | exit(1); | |
599 | } | |
5260325f | 600 | break; |
601 | case 'i': | |
602 | inetd_flag = 1; | |
603 | break; | |
604 | case 'Q': | |
a306f2dd | 605 | silent = 1; |
5260325f | 606 | break; |
607 | case 'q': | |
608 | options.log_level = SYSLOG_LEVEL_QUIET; | |
609 | break; | |
610 | case 'b': | |
611 | options.server_key_bits = atoi(optarg); | |
612 | break; | |
613 | case 'p': | |
48e671d5 | 614 | options.ports_from_cmdline = 1; |
bcbf86ec | 615 | if (options.num_ports >= MAX_PORTS) { |
616 | fprintf(stderr, "too many ports.\n"); | |
617 | exit(1); | |
618 | } | |
48e671d5 | 619 | options.ports[options.num_ports++] = atoi(optarg); |
5260325f | 620 | break; |
621 | case 'g': | |
622 | options.login_grace_time = atoi(optarg); | |
623 | break; | |
624 | case 'k': | |
625 | options.key_regeneration_time = atoi(optarg); | |
626 | break; | |
627 | case 'h': | |
fa08c86b | 628 | if (options.num_host_key_files >= MAX_HOSTKEYS) { |
629 | fprintf(stderr, "too many host keys.\n"); | |
630 | exit(1); | |
631 | } | |
632 | options.host_key_files[options.num_host_key_files++] = optarg; | |
5260325f | 633 | break; |
634 | case 'V': | |
635 | client_version_string = optarg; | |
636 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
637 | inetd_flag = 1; | |
638 | break; | |
c345cf9d | 639 | case 'u': |
640 | utmp_len = atoi(optarg); | |
641 | break; | |
5260325f | 642 | case '?': |
643 | default: | |
644 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
645 | fprintf(stderr, "Usage: %s [options]\n", av0); | |
646 | fprintf(stderr, "Options:\n"); | |
aa3378df | 647 | fprintf(stderr, " -f file Configuration file (default %s)\n", SERVER_CONFIG_FILE); |
bcbf86ec | 648 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); |
5260325f | 649 | fprintf(stderr, " -i Started from inetd\n"); |
650 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
651 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
652 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
653 | fprintf(stderr, " -g seconds Grace period for authentication (default: 300)\n"); | |
654 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
655 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
48e671d5 | 656 | HOST_KEY_FILE); |
c345cf9d | 657 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); |
48e671d5 | 658 | fprintf(stderr, " -4 Use IPv4 only\n"); |
659 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
5260325f | 660 | exit(1); |
661 | } | |
662 | } | |
663 | ||
48e671d5 | 664 | /* |
665 | * Force logging to stderr until we have loaded the private host | |
666 | * key (unless started from inetd) | |
667 | */ | |
668 | log_init(av0, | |
669 | options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level, | |
670 | options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility, | |
a306f2dd | 671 | !silent && !inetd_flag); |
48e671d5 | 672 | |
5260325f | 673 | /* Read server configuration options from the configuration file. */ |
674 | read_server_config(&options, config_file_name); | |
675 | ||
676 | /* Fill in default values for those options not explicitly set. */ | |
677 | fill_default_server_options(&options); | |
678 | ||
5260325f | 679 | /* Check that there are no remaining arguments. */ |
680 | if (optind < ac) { | |
681 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
682 | exit(1); | |
8efc0c15 | 683 | } |
5260325f | 684 | |
685 | debug("sshd version %.100s", SSH_VERSION); | |
686 | ||
fa08c86b | 687 | /* load private host keys */ |
688 | sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*)); | |
689 | sensitive_data.server_key = NULL; | |
690 | sensitive_data.ssh1_host_key = NULL; | |
691 | sensitive_data.have_ssh1_key = 0; | |
692 | sensitive_data.have_ssh2_key = 0; | |
a306f2dd | 693 | |
fa08c86b | 694 | for(i = 0; i < options.num_host_key_files; i++) { |
695 | Key *key = load_private_key_autodetect(options.host_key_files[i]); | |
696 | if (key == NULL) { | |
a306f2dd | 697 | error("Could not load host key: %.200s: %.100s", |
fa08c86b | 698 | options.host_key_files[i], strerror(errno)); |
699 | continue; | |
a306f2dd | 700 | } |
fa08c86b | 701 | switch(key->type){ |
702 | case KEY_RSA1: | |
703 | sensitive_data.ssh1_host_key = key; | |
704 | sensitive_data.have_ssh1_key = 1; | |
705 | break; | |
706 | case KEY_RSA: | |
707 | case KEY_DSA: | |
708 | sensitive_data.have_ssh2_key = 1; | |
709 | break; | |
a306f2dd | 710 | } |
fa08c86b | 711 | sensitive_data.host_keys[i] = key; |
712 | } | |
713 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
714 | log("Disabling protocol version 1. Could not load host key"); | |
715 | options.protocol &= ~SSH_PROTO_1; | |
716 | } | |
717 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
718 | log("Disabling protocol version 2. Could not load host key"); | |
719 | options.protocol &= ~SSH_PROTO_2; | |
a306f2dd | 720 | } |
721 | if (! options.protocol & (SSH_PROTO_1|SSH_PROTO_2)) { | |
722 | if (silent == 0) | |
723 | fprintf(stderr, "sshd: no hostkeys available -- exiting.\n"); | |
724 | log("sshd: no hostkeys available -- exiting.\n"); | |
5260325f | 725 | exit(1); |
726 | } | |
5260325f | 727 | |
a306f2dd | 728 | /* Check certain values for sanity. */ |
729 | if (options.protocol & SSH_PROTO_1) { | |
730 | if (options.server_key_bits < 512 || | |
731 | options.server_key_bits > 32768) { | |
732 | fprintf(stderr, "Bad server key size.\n"); | |
733 | exit(1); | |
734 | } | |
735 | /* | |
736 | * Check that server and host key lengths differ sufficiently. This | |
737 | * is necessary to make double encryption work with rsaref. Oh, I | |
738 | * hate software patents. I dont know if this can go? Niels | |
739 | */ | |
740 | if (options.server_key_bits > | |
fa08c86b | 741 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED && |
a306f2dd | 742 | options.server_key_bits < |
fa08c86b | 743 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { |
a306f2dd | 744 | options.server_key_bits = |
fa08c86b | 745 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED; |
a306f2dd | 746 | debug("Forcing server key to %d bits to make it differ from host key.", |
747 | options.server_key_bits); | |
748 | } | |
749 | } | |
750 | ||
77bb0bca | 751 | #ifdef HAVE_SCO_PROTECTED_PW |
752 | (void) set_auth_parameters(ac, av); | |
753 | #endif | |
754 | ||
a306f2dd | 755 | /* Initialize the log (it is reinitialized below in case we forked). */ |
5260325f | 756 | if (debug_flag && !inetd_flag) |
757 | log_stderr = 1; | |
758 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
759 | ||
a306f2dd | 760 | /* |
761 | * If not in debugging mode, and not started from inetd, disconnect | |
762 | * from the controlling terminal, and fork. The original process | |
763 | * exits. | |
764 | */ | |
5260325f | 765 | if (!debug_flag && !inetd_flag) { |
8efc0c15 | 766 | #ifdef TIOCNOTTY |
5260325f | 767 | int fd; |
8efc0c15 | 768 | #endif /* TIOCNOTTY */ |
5260325f | 769 | if (daemon(0, 0) < 0) |
770 | fatal("daemon() failed: %.200s", strerror(errno)); | |
771 | ||
772 | /* Disconnect from the controlling tty. */ | |
8efc0c15 | 773 | #ifdef TIOCNOTTY |
5260325f | 774 | fd = open("/dev/tty", O_RDWR | O_NOCTTY); |
775 | if (fd >= 0) { | |
776 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
777 | close(fd); | |
778 | } | |
8efc0c15 | 779 | #endif /* TIOCNOTTY */ |
8efc0c15 | 780 | } |
5260325f | 781 | /* Reinitialize the log (because of the fork above). */ |
782 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
783 | ||
5260325f | 784 | /* Initialize the random number generator. */ |
785 | arc4random_stir(); | |
786 | ||
787 | /* Chdir to the root directory so that the current disk can be | |
788 | unmounted if desired. */ | |
789 | chdir("/"); | |
790 | ||
5260325f | 791 | /* Start listening for a socket, unless started from inetd. */ |
792 | if (inetd_flag) { | |
793 | int s1, s2; | |
794 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ | |
795 | s2 = dup(s1); | |
796 | sock_in = dup(0); | |
797 | sock_out = dup(1); | |
4c8722d9 | 798 | startup_pipe = -1; |
a306f2dd | 799 | /* |
800 | * We intentionally do not close the descriptors 0, 1, and 2 | |
801 | * as our code for setting the descriptors won\'t work if | |
802 | * ttyfd happens to be one of those. | |
803 | */ | |
5260325f | 804 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); |
fa08c86b | 805 | if (options.protocol & SSH_PROTO_1) |
806 | generate_empheral_server_key(); | |
5260325f | 807 | } else { |
48e671d5 | 808 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
809 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
810 | continue; | |
811 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
812 | fatal("Too many listen sockets. " | |
813 | "Enlarge MAX_LISTEN_SOCKS"); | |
814 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
815 | ntop, sizeof(ntop), strport, sizeof(strport), | |
816 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
817 | error("getnameinfo failed"); | |
818 | continue; | |
819 | } | |
820 | /* Create socket for listening. */ | |
821 | listen_sock = socket(ai->ai_family, SOCK_STREAM, 0); | |
822 | if (listen_sock < 0) { | |
823 | /* kernel may not support ipv6 */ | |
824 | verbose("socket: %.100s", strerror(errno)); | |
825 | continue; | |
826 | } | |
827 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
828 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
829 | close(listen_sock); | |
830 | continue; | |
831 | } | |
832 | /* | |
833 | * Set socket options. We try to make the port | |
834 | * reusable and have it close as fast as possible | |
835 | * without waiting in unnecessary wait states on | |
836 | * close. | |
837 | */ | |
838 | setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, | |
839 | (void *) &on, sizeof(on)); | |
840 | linger.l_onoff = 1; | |
841 | linger.l_linger = 5; | |
842 | setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, | |
843 | (void *) &linger, sizeof(linger)); | |
844 | ||
845 | debug("Bind to port %s on %s.", strport, ntop); | |
846 | ||
847 | /* Bind the socket to the desired port. */ | |
16218745 | 848 | if ((bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) && |
849 | (!ai->ai_next)) { | |
48e671d5 | 850 | error("Bind to port %s on %s failed: %.200s.", |
851 | strport, ntop, strerror(errno)); | |
852 | close(listen_sock); | |
853 | continue; | |
854 | } | |
855 | listen_socks[num_listen_socks] = listen_sock; | |
856 | num_listen_socks++; | |
857 | ||
858 | /* Start listening on the port. */ | |
859 | log("Server listening on %s port %s.", ntop, strport); | |
860 | if (listen(listen_sock, 5) < 0) | |
861 | fatal("listen: %.100s", strerror(errno)); | |
862 | ||
5260325f | 863 | } |
48e671d5 | 864 | freeaddrinfo(options.listen_addrs); |
865 | ||
866 | if (!num_listen_socks) | |
867 | fatal("Cannot bind any address."); | |
868 | ||
5260325f | 869 | if (!debug_flag) { |
aa3378df | 870 | /* |
871 | * Record our pid in /etc/sshd_pid to make it easier | |
872 | * to kill the correct sshd. We don\'t want to do | |
873 | * this before the bind above because the bind will | |
874 | * fail if there already is a daemon, and this will | |
875 | * overwrite any old pid in the file. | |
876 | */ | |
3c62e7eb | 877 | f = fopen(options.pid_file, "wb"); |
5260325f | 878 | if (f) { |
879 | fprintf(f, "%u\n", (unsigned int) getpid()); | |
880 | fclose(f); | |
881 | } | |
8efc0c15 | 882 | } |
a306f2dd | 883 | if (options.protocol & SSH_PROTO_1) { |
fa08c86b | 884 | generate_empheral_server_key(); |
5260325f | 885 | |
a306f2dd | 886 | /* Schedule server key regeneration alarm. */ |
887 | signal(SIGALRM, key_regeneration_alarm); | |
888 | alarm(options.key_regeneration_time); | |
889 | } | |
5260325f | 890 | |
891 | /* Arrange to restart on SIGHUP. The handler needs listen_sock. */ | |
892 | signal(SIGHUP, sighup_handler); | |
089fbbd2 | 893 | |
5260325f | 894 | signal(SIGTERM, sigterm_handler); |
895 | signal(SIGQUIT, sigterm_handler); | |
896 | ||
897 | /* Arrange SIGCHLD to be caught. */ | |
898 | signal(SIGCHLD, main_sigchld_handler); | |
899 | ||
48e671d5 | 900 | /* setup fd set for listen */ |
089fbbd2 | 901 | fdset = NULL; |
48e671d5 | 902 | maxfd = 0; |
903 | for (i = 0; i < num_listen_socks; i++) | |
904 | if (listen_socks[i] > maxfd) | |
905 | maxfd = listen_socks[i]; | |
089fbbd2 | 906 | /* pipes connected to unauthenticated childs */ |
907 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
908 | for (i = 0; i < options.max_startups; i++) | |
909 | startup_pipes[i] = -1; | |
48e671d5 | 910 | |
aa3378df | 911 | /* |
912 | * Stay listening for connections until the system crashes or | |
913 | * the daemon is killed with a signal. | |
914 | */ | |
5260325f | 915 | for (;;) { |
916 | if (received_sighup) | |
917 | sighup_restart(); | |
089fbbd2 | 918 | if (fdset != NULL) |
919 | xfree(fdset); | |
920 | fdsetsz = howmany(maxfd, NFDBITS) * sizeof(fd_mask); | |
921 | fdset = (fd_set *)xmalloc(fdsetsz); | |
48e671d5 | 922 | memset(fdset, 0, fdsetsz); |
089fbbd2 | 923 | |
48e671d5 | 924 | for (i = 0; i < num_listen_socks; i++) |
925 | FD_SET(listen_socks[i], fdset); | |
089fbbd2 | 926 | for (i = 0; i < options.max_startups; i++) |
927 | if (startup_pipes[i] != -1) | |
928 | FD_SET(startup_pipes[i], fdset); | |
929 | ||
930 | /* Wait in select until there is a connection. */ | |
48e671d5 | 931 | if (select(maxfd + 1, fdset, NULL, NULL, NULL) < 0) { |
932 | if (errno != EINTR) | |
933 | error("select: %.100s", strerror(errno)); | |
2d86a6cc | 934 | continue; |
48e671d5 | 935 | } |
089fbbd2 | 936 | for (i = 0; i < options.max_startups; i++) |
937 | if (startup_pipes[i] != -1 && | |
938 | FD_ISSET(startup_pipes[i], fdset)) { | |
939 | /* | |
940 | * the read end of the pipe is ready | |
941 | * if the child has closed the pipe | |
942 | * after successfull authentication | |
943 | * or if the child has died | |
944 | */ | |
945 | close(startup_pipes[i]); | |
946 | startup_pipes[i] = -1; | |
947 | startups--; | |
948 | } | |
48e671d5 | 949 | for (i = 0; i < num_listen_socks; i++) { |
950 | if (!FD_ISSET(listen_socks[i], fdset)) | |
5260325f | 951 | continue; |
089fbbd2 | 952 | fromlen = sizeof(from); |
953 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
954 | &fromlen); | |
955 | if (newsock < 0) { | |
956 | if (errno != EINTR && errno != EWOULDBLOCK) | |
957 | error("accept: %.100s", strerror(errno)); | |
958 | continue; | |
959 | } | |
960 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
961 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
962 | continue; | |
963 | } | |
c345cf9d | 964 | if (drop_connection(startups) == 1) { |
965 | debug("drop connection #%d", startups); | |
089fbbd2 | 966 | close(newsock); |
967 | continue; | |
968 | } | |
969 | if (pipe(startup_p) == -1) { | |
970 | close(newsock); | |
971 | continue; | |
972 | } | |
973 | ||
974 | for (j = 0; j < options.max_startups; j++) | |
975 | if (startup_pipes[j] == -1) { | |
976 | startup_pipes[j] = startup_p[0]; | |
977 | if (maxfd < startup_p[0]) | |
978 | maxfd = startup_p[0]; | |
979 | startups++; | |
980 | break; | |
981 | } | |
982 | ||
aa3378df | 983 | /* |
089fbbd2 | 984 | * Got connection. Fork a child to handle it, unless |
985 | * we are in debugging mode. | |
aa3378df | 986 | */ |
089fbbd2 | 987 | if (debug_flag) { |
aa3378df | 988 | /* |
089fbbd2 | 989 | * In debugging mode. Close the listening |
990 | * socket, and start processing the | |
991 | * connection without forking. | |
aa3378df | 992 | */ |
089fbbd2 | 993 | debug("Server will not fork when running in debugging mode."); |
48e671d5 | 994 | close_listen_socks(); |
5260325f | 995 | sock_in = newsock; |
996 | sock_out = newsock; | |
5540ea9b | 997 | startup_pipe = -1; |
3f7a7e4a | 998 | pid = getpid(); |
5260325f | 999 | break; |
089fbbd2 | 1000 | } else { |
1001 | /* | |
1002 | * Normal production daemon. Fork, and have | |
1003 | * the child process the connection. The | |
1004 | * parent continues listening. | |
1005 | */ | |
1006 | if ((pid = fork()) == 0) { | |
1007 | /* | |
1008 | * Child. Close the listening and max_startup | |
1009 | * sockets. Start using the accepted socket. | |
1010 | * Reinitialize logging (since our pid has | |
1011 | * changed). We break out of the loop to handle | |
1012 | * the connection. | |
1013 | */ | |
1014 | startup_pipe = startup_p[1]; | |
1015 | for (j = 0; j < options.max_startups; j++) | |
1016 | if (startup_pipes[j] != -1) | |
1017 | close(startup_pipes[j]); | |
1018 | close_listen_socks(); | |
1019 | sock_in = newsock; | |
1020 | sock_out = newsock; | |
1021 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
1022 | break; | |
1023 | } | |
5260325f | 1024 | } |
5260325f | 1025 | |
089fbbd2 | 1026 | /* Parent. Stay in the loop. */ |
1027 | if (pid < 0) | |
1028 | error("fork: %.100s", strerror(errno)); | |
1029 | else | |
1030 | debug("Forked child %d.", pid); | |
5260325f | 1031 | |
089fbbd2 | 1032 | close(startup_p[1]); |
5260325f | 1033 | |
089fbbd2 | 1034 | /* Mark that the key has been used (it was "given" to the child). */ |
1035 | key_used = 1; | |
5260325f | 1036 | |
089fbbd2 | 1037 | arc4random_stir(); |
1038 | ||
1039 | /* Close the new socket (the child is now taking care of it). */ | |
1040 | close(newsock); | |
1041 | } | |
48e671d5 | 1042 | /* child process check (or debug mode) */ |
1043 | if (num_listen_socks < 0) | |
1044 | break; | |
5260325f | 1045 | } |
1046 | } | |
8efc0c15 | 1047 | |
5260325f | 1048 | /* This is the child processing a new connection. */ |
1049 | ||
aa3378df | 1050 | /* |
1051 | * Disable the key regeneration alarm. We will not regenerate the | |
1052 | * key since we are no longer in a position to give it to anyone. We | |
1053 | * will not restart on SIGHUP since it no longer makes sense. | |
1054 | */ | |
5260325f | 1055 | alarm(0); |
1056 | signal(SIGALRM, SIG_DFL); | |
1057 | signal(SIGHUP, SIG_DFL); | |
1058 | signal(SIGTERM, SIG_DFL); | |
1059 | signal(SIGQUIT, SIG_DFL); | |
1060 | signal(SIGCHLD, SIG_DFL); | |
9aaf9be4 | 1061 | signal(SIGINT, SIG_DFL); |
5260325f | 1062 | |
aa3378df | 1063 | /* |
1064 | * Set socket options for the connection. We want the socket to | |
1065 | * close as fast as possible without waiting for anything. If the | |
1066 | * connection is not a socket, these will do nothing. | |
1067 | */ | |
1068 | /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 1069 | linger.l_onoff = 1; |
1070 | linger.l_linger = 5; | |
1071 | setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
1072 | ||
aa3378df | 1073 | /* |
1074 | * Register our connection. This turns encryption off because we do | |
1075 | * not have a key. | |
1076 | */ | |
5260325f | 1077 | packet_set_connection(sock_in, sock_out); |
1078 | ||
1079 | remote_port = get_remote_port(); | |
1080 | remote_ip = get_remote_ipaddr(); | |
1081 | ||
1082 | /* Check whether logins are denied from this host. */ | |
1083 | #ifdef LIBWRAP | |
48e671d5 | 1084 | /* XXX LIBWRAP noes not know about IPv6 */ |
5260325f | 1085 | { |
1086 | struct request_info req; | |
8efc0c15 | 1087 | |
5260325f | 1088 | request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL); |
1089 | fromhost(&req); | |
8efc0c15 | 1090 | |
5260325f | 1091 | if (!hosts_access(&req)) { |
1092 | close(sock_in); | |
1093 | close(sock_out); | |
1094 | refuse(&req); | |
1095 | } | |
48e671d5 | 1096 | /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */ |
8efc0c15 | 1097 | } |
48e671d5 | 1098 | #endif /* LIBWRAP */ |
5260325f | 1099 | /* Log the connection. */ |
1100 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
8efc0c15 | 1101 | |
aa3378df | 1102 | /* |
1103 | * We don\'t want to listen forever unless the other side | |
1104 | * successfully authenticates itself. So we set up an alarm which is | |
1105 | * cleared after successful authentication. A limit of zero | |
1106 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1107 | * mode; it is just annoying to have the server exit just when you | |
1108 | * are about to discover the bug. | |
1109 | */ | |
5260325f | 1110 | signal(SIGALRM, grace_alarm_handler); |
1111 | if (!debug_flag) | |
1112 | alarm(options.login_grace_time); | |
1113 | ||
7368a6c8 | 1114 | sshd_exchange_identification(sock_in, sock_out); |
aa3378df | 1115 | /* |
1116 | * Check that the connection comes from a privileged port. Rhosts- | |
1117 | * and Rhosts-RSA-Authentication only make sense from priviledged | |
1118 | * programs. Of course, if the intruder has root access on his local | |
1119 | * machine, he can connect from any port. So do not use these | |
1120 | * authentication methods from machines that you do not trust. | |
1121 | */ | |
5260325f | 1122 | if (remote_port >= IPPORT_RESERVED || |
1123 | remote_port < IPPORT_RESERVED / 2) { | |
fa08c86b | 1124 | debug("Rhosts Authentication methods disabled, " |
1125 | "originating port not trusted."); | |
5260325f | 1126 | options.rhosts_authentication = 0; |
1127 | options.rhosts_rsa_authentication = 0; | |
1128 | } | |
48e671d5 | 1129 | #ifdef KRB4 |
1130 | if (!packet_connection_is_ipv4() && | |
1131 | options.kerberos_authentication) { | |
1132 | debug("Kerberos Authentication disabled, only available for IPv4."); | |
1133 | options.kerberos_authentication = 0; | |
1134 | } | |
1135 | #endif /* KRB4 */ | |
1136 | ||
5260325f | 1137 | packet_set_nonblocking(); |
1138 | ||
7b2ea3a1 | 1139 | /* perform the key exchange */ |
7b2ea3a1 | 1140 | /* authenticate user and start session */ |
e78a59f5 | 1141 | if (compat20) { |
1142 | do_ssh2_kex(); | |
1143 | do_authentication2(); | |
1144 | } else { | |
1145 | do_ssh1_kex(); | |
1146 | do_authentication(); | |
1147 | } | |
8efc0c15 | 1148 | |
1149 | #ifdef KRB4 | |
5260325f | 1150 | /* Cleanup user's ticket cache file. */ |
1151 | if (options.kerberos_ticket_cleanup) | |
1152 | (void) dest_tkt(); | |
8efc0c15 | 1153 | #endif /* KRB4 */ |
1154 | ||
5260325f | 1155 | /* The connection has been terminated. */ |
1156 | verbose("Closing connection to %.100s", remote_ip); | |
8efc0c15 | 1157 | |
d94aa2ae | 1158 | #ifdef USE_PAM |
a5c9cd31 | 1159 | finish_pam(); |
d94aa2ae | 1160 | #endif /* USE_PAM */ |
8efc0c15 | 1161 | |
5260325f | 1162 | packet_close(); |
1163 | exit(0); | |
1164 | } | |
8efc0c15 | 1165 | |
5260325f | 1166 | /* |
7b2ea3a1 | 1167 | * SSH1 key exchange |
5260325f | 1168 | */ |
e7c0f9d5 | 1169 | void |
7368a6c8 | 1170 | do_ssh1_kex() |
8efc0c15 | 1171 | { |
5260325f | 1172 | int i, len; |
7b2ea3a1 | 1173 | int plen, slen; |
5260325f | 1174 | BIGNUM *session_key_int; |
1175 | unsigned char session_key[SSH_SESSION_KEY_LENGTH]; | |
7b2ea3a1 | 1176 | unsigned char cookie[8]; |
5260325f | 1177 | unsigned int cipher_type, auth_mask, protocol_flags; |
5260325f | 1178 | u_int32_t rand = 0; |
1179 | ||
aa3378df | 1180 | /* |
1181 | * Generate check bytes that the client must send back in the user | |
1182 | * packet in order for it to be accepted; this is used to defy ip | |
1183 | * spoofing attacks. Note that this only works against somebody | |
1184 | * doing IP spoofing from a remote machine; any machine on the local | |
1185 | * network can still see outgoing packets and catch the random | |
1186 | * cookie. This only affects rhosts authentication, and this is one | |
1187 | * of the reasons why it is inherently insecure. | |
1188 | */ | |
5260325f | 1189 | for (i = 0; i < 8; i++) { |
1190 | if (i % 4 == 0) | |
1191 | rand = arc4random(); | |
7b2ea3a1 | 1192 | cookie[i] = rand & 0xff; |
5260325f | 1193 | rand >>= 8; |
1194 | } | |
1195 | ||
aa3378df | 1196 | /* |
1197 | * Send our public key. We include in the packet 64 bits of random | |
1198 | * data that must be matched in the reply in order to prevent IP | |
1199 | * spoofing. | |
1200 | */ | |
5260325f | 1201 | packet_start(SSH_SMSG_PUBLIC_KEY); |
1202 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1203 | packet_put_char(cookie[i]); |
5260325f | 1204 | |
1205 | /* Store our public server RSA key. */ | |
fa08c86b | 1206 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); |
1207 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1208 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
5260325f | 1209 | |
1210 | /* Store our public host RSA key. */ | |
fa08c86b | 1211 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); |
1212 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1213 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
5260325f | 1214 | |
1215 | /* Put protocol flags. */ | |
1216 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1217 | ||
1218 | /* Declare which ciphers we support. */ | |
94ec8c6b | 1219 | packet_put_int(cipher_mask_ssh1(0)); |
5260325f | 1220 | |
1221 | /* Declare supported authentication types. */ | |
1222 | auth_mask = 0; | |
1223 | if (options.rhosts_authentication) | |
1224 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
1225 | if (options.rhosts_rsa_authentication) | |
1226 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1227 | if (options.rsa_authentication) | |
1228 | auth_mask |= 1 << SSH_AUTH_RSA; | |
8efc0c15 | 1229 | #ifdef KRB4 |
5260325f | 1230 | if (options.kerberos_authentication) |
1231 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
8efc0c15 | 1232 | #endif |
1233 | #ifdef AFS | |
5260325f | 1234 | if (options.kerberos_tgt_passing) |
1235 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
1236 | if (options.afs_token_passing) | |
1237 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
8efc0c15 | 1238 | #endif |
5260325f | 1239 | #ifdef SKEY |
1240 | if (options.skey_authentication == 1) | |
1241 | auth_mask |= 1 << SSH_AUTH_TIS; | |
1242 | #endif | |
1243 | if (options.password_authentication) | |
1244 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1245 | packet_put_int(auth_mask); | |
1246 | ||
1247 | /* Send the packet and wait for it to be sent. */ | |
1248 | packet_send(); | |
1249 | packet_write_wait(); | |
1250 | ||
fa08c86b | 1251 | debug("Sent %d bit server key and %d bit host key.", |
1252 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1253 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
5260325f | 1254 | |
1255 | /* Read clients reply (cipher type and session key). */ | |
1256 | packet_read_expect(&plen, SSH_CMSG_SESSION_KEY); | |
1257 | ||
2d86a6cc | 1258 | /* Get cipher type and check whether we accept this. */ |
5260325f | 1259 | cipher_type = packet_get_char(); |
1260 | ||
94ec8c6b | 1261 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) |
2d86a6cc | 1262 | packet_disconnect("Warning: client selects unsupported cipher."); |
1263 | ||
5260325f | 1264 | /* Get check bytes from the packet. These must match those we |
1265 | sent earlier with the public key packet. */ | |
1266 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1267 | if (cookie[i] != packet_get_char()) |
5260325f | 1268 | packet_disconnect("IP Spoofing check bytes do not match."); |
1269 | ||
1270 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1271 | ||
1272 | /* Get the encrypted integer. */ | |
1273 | session_key_int = BN_new(); | |
1274 | packet_get_bignum(session_key_int, &slen); | |
1275 | ||
5260325f | 1276 | protocol_flags = packet_get_int(); |
1277 | packet_set_protocol_flags(protocol_flags); | |
1278 | ||
1279 | packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY); | |
1280 | ||
aa3378df | 1281 | /* |
1282 | * Decrypt it using our private server key and private host key (key | |
1283 | * with larger modulus first). | |
1284 | */ | |
fa08c86b | 1285 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { |
5260325f | 1286 | /* Private key has bigger modulus. */ |
fa08c86b | 1287 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < |
1288 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1289 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1290 | get_remote_ipaddr(), | |
1291 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1292 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1293 | SSH_KEY_BITS_RESERVED); | |
5260325f | 1294 | } |
1295 | rsa_private_decrypt(session_key_int, session_key_int, | |
fa08c86b | 1296 | sensitive_data.server_key->rsa); |
5260325f | 1297 | rsa_private_decrypt(session_key_int, session_key_int, |
fa08c86b | 1298 | sensitive_data.ssh1_host_key->rsa); |
5260325f | 1299 | } else { |
1300 | /* Host key has bigger modulus (or they are equal). */ | |
fa08c86b | 1301 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < |
1302 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1303 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1304 | get_remote_ipaddr(), | |
1305 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1306 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1307 | SSH_KEY_BITS_RESERVED); | |
5260325f | 1308 | } |
1309 | rsa_private_decrypt(session_key_int, session_key_int, | |
fa08c86b | 1310 | sensitive_data.ssh1_host_key->rsa); |
5260325f | 1311 | rsa_private_decrypt(session_key_int, session_key_int, |
fa08c86b | 1312 | sensitive_data.server_key->rsa); |
5260325f | 1313 | } |
1314 | ||
7b2ea3a1 | 1315 | compute_session_id(session_id, cookie, |
fa08c86b | 1316 | sensitive_data.ssh1_host_key->rsa->n, |
1317 | sensitive_data.server_key->rsa->n); | |
5260325f | 1318 | |
7b2ea3a1 | 1319 | /* Destroy the private and public keys. They will no longer be needed. */ |
a306f2dd | 1320 | destroy_sensitive_data(); |
7b2ea3a1 | 1321 | |
aa3378df | 1322 | /* |
1323 | * Extract session key from the decrypted integer. The key is in the | |
1324 | * least significant 256 bits of the integer; the first byte of the | |
1325 | * key is in the highest bits. | |
1326 | */ | |
5260325f | 1327 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); |
1328 | len = BN_num_bytes(session_key_int); | |
1329 | if (len < 0 || len > sizeof(session_key)) | |
1330 | fatal("do_connection: bad len from %s: session_key_int %d > sizeof(session_key) %d", | |
fa08c86b | 1331 | get_remote_ipaddr(), |
1332 | len, sizeof(session_key)); | |
5260325f | 1333 | memset(session_key, 0, sizeof(session_key)); |
1334 | BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len); | |
1335 | ||
7b2ea3a1 | 1336 | /* Destroy the decrypted integer. It is no longer needed. */ |
1337 | BN_clear_free(session_key_int); | |
1338 | ||
5260325f | 1339 | /* Xor the first 16 bytes of the session key with the session id. */ |
1340 | for (i = 0; i < 16; i++) | |
1341 | session_key[i] ^= session_id[i]; | |
1342 | ||
5260325f | 1343 | /* Set the session key. From this on all communications will be encrypted. */ |
1344 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1345 | ||
1346 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1347 | memset(session_key, 0, sizeof(session_key)); | |
1348 | ||
1349 | debug("Received session key; encryption turned on."); | |
1350 | ||
1351 | /* Send an acknowledgement packet. Note that this packet is sent encrypted. */ | |
1352 | packet_start(SSH_SMSG_SUCCESS); | |
1353 | packet_send(); | |
1354 | packet_write_wait(); | |
5260325f | 1355 | } |
e78a59f5 | 1356 | |
1357 | /* | |
1358 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1359 | */ | |
1360 | void | |
1361 | do_ssh2_kex() | |
1362 | { | |
1363 | Buffer *server_kexinit; | |
1364 | Buffer *client_kexinit; | |
94ec8c6b | 1365 | int payload_len; |
e78a59f5 | 1366 | int i; |
e78a59f5 | 1367 | Kex *kex; |
e78a59f5 | 1368 | char *cprop[PROPOSAL_MAX]; |
e78a59f5 | 1369 | |
1370 | /* KEXINIT */ | |
1371 | ||
a8be9f80 | 1372 | if (options.ciphers != NULL) { |
6ae2364d | 1373 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
a8be9f80 | 1374 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
1375 | } | |
fa08c86b | 1376 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
1377 | ||
71276795 | 1378 | server_kexinit = kex_init(myproposal); |
e78a59f5 | 1379 | client_kexinit = xmalloc(sizeof(*client_kexinit)); |
1380 | buffer_init(client_kexinit); | |
e78a59f5 | 1381 | |
71276795 | 1382 | /* algorithm negotiation */ |
1383 | kex_exchange_kexinit(server_kexinit, client_kexinit, cprop); | |
1384 | kex = kex_choose_conf(cprop, myproposal, 1); | |
1385 | for (i = 0; i < PROPOSAL_MAX; i++) | |
1386 | xfree(cprop[i]); | |
e78a59f5 | 1387 | |
94ec8c6b | 1388 | switch (kex->kex_type) { |
1389 | case DH_GRP1_SHA1: | |
1390 | ssh_dh1_server(kex, client_kexinit, server_kexinit); | |
1391 | break; | |
1392 | case DH_GEX_SHA1: | |
1393 | ssh_dhgex_server(kex, client_kexinit, server_kexinit); | |
1394 | break; | |
1395 | default: | |
1396 | fatal("Unsupported key exchange %d", kex->kex_type); | |
1397 | } | |
1398 | ||
1399 | debug("send SSH2_MSG_NEWKEYS."); | |
1400 | packet_start(SSH2_MSG_NEWKEYS); | |
1401 | packet_send(); | |
1402 | packet_write_wait(); | |
1403 | debug("done: send SSH2_MSG_NEWKEYS."); | |
1404 | ||
1405 | debug("Wait SSH2_MSG_NEWKEYS."); | |
1406 | packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS); | |
1407 | debug("GOT SSH2_MSG_NEWKEYS."); | |
1408 | ||
1409 | #ifdef DEBUG_KEXDH | |
1410 | /* send 1st encrypted/maced/compressed message */ | |
1411 | packet_start(SSH2_MSG_IGNORE); | |
1412 | packet_put_cstring("markus"); | |
1413 | packet_send(); | |
1414 | packet_write_wait(); | |
1415 | #endif | |
1416 | ||
1417 | debug("done: KEX2."); | |
1418 | } | |
1419 | ||
1420 | /* | |
1421 | * SSH2 key exchange | |
1422 | */ | |
1423 | ||
1424 | /* diffie-hellman-group1-sha1 */ | |
1425 | ||
1426 | void | |
1427 | ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit) | |
1428 | { | |
1429 | #ifdef DEBUG_KEXDH | |
1430 | int i; | |
1431 | #endif | |
1432 | int payload_len, dlen; | |
1433 | int slen; | |
1434 | unsigned char *signature = NULL; | |
1435 | unsigned char *server_host_key_blob = NULL; | |
1436 | unsigned int sbloblen; | |
1437 | unsigned int klen, kout; | |
1438 | unsigned char *kbuf; | |
1439 | unsigned char *hash; | |
1440 | BIGNUM *shared_secret = 0; | |
1441 | DH *dh; | |
1442 | BIGNUM *dh_client_pub = 0; | |
fa08c86b | 1443 | Key *hostkey; |
1444 | ||
1445 | hostkey = get_hostkey_by_type(kex->hostkey_type); | |
1446 | if (hostkey == NULL) | |
1447 | fatal("Unsupported hostkey type %d", kex->hostkey_type); | |
e78a59f5 | 1448 | |
94ec8c6b | 1449 | /* KEXDH */ |
e78a59f5 | 1450 | debug("Wait SSH2_MSG_KEXDH_INIT."); |
1451 | packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT); | |
1452 | ||
1453 | /* key, cert */ | |
1454 | dh_client_pub = BN_new(); | |
1455 | if (dh_client_pub == NULL) | |
1456 | fatal("dh_client_pub == NULL"); | |
1457 | packet_get_bignum2(dh_client_pub, &dlen); | |
1458 | ||
1459 | #ifdef DEBUG_KEXDH | |
1460 | fprintf(stderr, "\ndh_client_pub= "); | |
188adeb2 | 1461 | BN_print_fp(stderr, dh_client_pub); |
e78a59f5 | 1462 | fprintf(stderr, "\n"); |
1463 | debug("bits %d", BN_num_bits(dh_client_pub)); | |
1464 | #endif | |
1465 | ||
1466 | /* generate DH key */ | |
a8be9f80 | 1467 | dh = dh_new_group1(); /* XXX depends on 'kex' */ |
e78a59f5 | 1468 | |
1469 | #ifdef DEBUG_KEXDH | |
1470 | fprintf(stderr, "\np= "); | |
188adeb2 | 1471 | BN_print_fp(stderr, dh->p); |
e78a59f5 | 1472 | fprintf(stderr, "\ng= "); |
188adeb2 | 1473 | bn_print(dh->g); |
e78a59f5 | 1474 | fprintf(stderr, "\npub= "); |
188adeb2 | 1475 | BN_print_fp(stderr, dh->pub_key); |
e78a59f5 | 1476 | fprintf(stderr, "\n"); |
188adeb2 | 1477 | DHparams_print_fp(stderr, dh); |
e78a59f5 | 1478 | #endif |
a8be9f80 | 1479 | if (!dh_pub_is_valid(dh, dh_client_pub)) |
1480 | packet_disconnect("bad client public DH value"); | |
e78a59f5 | 1481 | |
1482 | klen = DH_size(dh); | |
1483 | kbuf = xmalloc(klen); | |
1484 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | |
1485 | ||
1486 | #ifdef DEBUG_KEXDH | |
1487 | debug("shared secret: len %d/%d", klen, kout); | |
1488 | fprintf(stderr, "shared secret == "); | |
1489 | for (i = 0; i< kout; i++) | |
1490 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
1491 | fprintf(stderr, "\n"); | |
1492 | #endif | |
1493 | shared_secret = BN_new(); | |
1494 | ||
1495 | BN_bin2bn(kbuf, kout, shared_secret); | |
1496 | memset(kbuf, 0, klen); | |
1497 | xfree(kbuf); | |
1498 | ||
a306f2dd | 1499 | /* XXX precompute? */ |
fa08c86b | 1500 | key_to_blob(hostkey, &server_host_key_blob, &sbloblen); |
e78a59f5 | 1501 | |
1502 | /* calc H */ /* XXX depends on 'kex' */ | |
1503 | hash = kex_hash( | |
1504 | client_version_string, | |
1505 | server_version_string, | |
1506 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
1507 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
1508 | (char *)server_host_key_blob, sbloblen, | |
1509 | dh_client_pub, | |
1510 | dh->pub_key, | |
1511 | shared_secret | |
1512 | ); | |
1513 | buffer_free(client_kexinit); | |
1514 | buffer_free(server_kexinit); | |
1515 | xfree(client_kexinit); | |
1516 | xfree(server_kexinit); | |
1517 | #ifdef DEBUG_KEXDH | |
6ae2364d | 1518 | fprintf(stderr, "hash == "); |
1519 | for (i = 0; i< 20; i++) | |
1520 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
1521 | fprintf(stderr, "\n"); | |
e78a59f5 | 1522 | #endif |
a306f2dd | 1523 | /* save session id := H */ |
1524 | /* XXX hashlen depends on KEX */ | |
1525 | session_id2_len = 20; | |
1526 | session_id2 = xmalloc(session_id2_len); | |
1527 | memcpy(session_id2, hash, session_id2_len); | |
1528 | ||
e78a59f5 | 1529 | /* sign H */ |
a306f2dd | 1530 | /* XXX hashlen depends on KEX */ |
fa08c86b | 1531 | key_sign(hostkey, &signature, &slen, hash, 20); |
a306f2dd | 1532 | |
1533 | destroy_sensitive_data(); | |
e78a59f5 | 1534 | |
1535 | /* send server hostkey, DH pubkey 'f' and singed H */ | |
1536 | packet_start(SSH2_MSG_KEXDH_REPLY); | |
1537 | packet_put_string((char *)server_host_key_blob, sbloblen); | |
1d1ffb87 | 1538 | packet_put_bignum2(dh->pub_key); /* f */ |
e78a59f5 | 1539 | packet_put_string((char *)signature, slen); |
1540 | packet_send(); | |
d6f24e45 | 1541 | xfree(signature); |
a306f2dd | 1542 | xfree(server_host_key_blob); |
e78a59f5 | 1543 | packet_write_wait(); |
1544 | ||
1545 | kex_derive_keys(kex, hash, shared_secret); | |
1546 | packet_set_kex(kex); | |
1547 | ||
1548 | /* have keys, free DH */ | |
1549 | DH_free(dh); | |
94ec8c6b | 1550 | } |
e78a59f5 | 1551 | |
94ec8c6b | 1552 | /* diffie-hellman-group-exchange-sha1 */ |
1553 | ||
1554 | void | |
1555 | ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit) | |
1556 | { | |
1557 | #ifdef DEBUG_KEXDH | |
1558 | int i; | |
1559 | #endif | |
1560 | int payload_len, dlen; | |
1561 | int slen, nbits; | |
1562 | unsigned char *signature = NULL; | |
1563 | unsigned char *server_host_key_blob = NULL; | |
1564 | unsigned int sbloblen; | |
1565 | unsigned int klen, kout; | |
1566 | unsigned char *kbuf; | |
1567 | unsigned char *hash; | |
1568 | BIGNUM *shared_secret = 0; | |
1569 | DH *dh; | |
1570 | BIGNUM *dh_client_pub = 0; | |
fa08c86b | 1571 | Key *hostkey; |
1572 | ||
1573 | hostkey = get_hostkey_by_type(kex->hostkey_type); | |
1574 | if (hostkey == NULL) | |
1575 | fatal("Unsupported hostkey type %d", kex->hostkey_type); | |
94ec8c6b | 1576 | |
1577 | /* KEXDHGEX */ | |
1578 | debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST."); | |
1579 | packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_REQUEST); | |
1580 | nbits = packet_get_int(); | |
1581 | dh = choose_dh(nbits); | |
1582 | ||
1583 | debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP."); | |
1584 | packet_start(SSH2_MSG_KEX_DH_GEX_GROUP); | |
1585 | packet_put_bignum2(dh->p); | |
1586 | packet_put_bignum2(dh->g); | |
e78a59f5 | 1587 | packet_send(); |
1588 | packet_write_wait(); | |
e78a59f5 | 1589 | |
94ec8c6b | 1590 | debug("Wait SSH2_MSG_KEX_DH_GEX_INIT."); |
1591 | packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_INIT); | |
1592 | ||
1593 | /* key, cert */ | |
1594 | dh_client_pub = BN_new(); | |
1595 | if (dh_client_pub == NULL) | |
1596 | fatal("dh_client_pub == NULL"); | |
1597 | packet_get_bignum2(dh_client_pub, &dlen); | |
e78a59f5 | 1598 | |
a8be9f80 | 1599 | #ifdef DEBUG_KEXDH |
94ec8c6b | 1600 | fprintf(stderr, "\ndh_client_pub= "); |
1601 | BN_print_fp(stderr, dh_client_pub); | |
1602 | fprintf(stderr, "\n"); | |
1603 | debug("bits %d", BN_num_bits(dh_client_pub)); | |
1604 | #endif | |
1605 | ||
1606 | #ifdef DEBUG_KEXDH | |
1607 | fprintf(stderr, "\np= "); | |
1608 | BN_print_fp(stderr, dh->p); | |
1609 | fprintf(stderr, "\ng= "); | |
1610 | bn_print(dh->g); | |
1611 | fprintf(stderr, "\npub= "); | |
1612 | BN_print_fp(stderr, dh->pub_key); | |
1613 | fprintf(stderr, "\n"); | |
1614 | DHparams_print_fp(stderr, dh); | |
1615 | #endif | |
1616 | if (!dh_pub_is_valid(dh, dh_client_pub)) | |
1617 | packet_disconnect("bad client public DH value"); | |
1618 | ||
1619 | klen = DH_size(dh); | |
1620 | kbuf = xmalloc(klen); | |
1621 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | |
1622 | ||
1623 | #ifdef DEBUG_KEXDH | |
1624 | debug("shared secret: len %d/%d", klen, kout); | |
1625 | fprintf(stderr, "shared secret == "); | |
1626 | for (i = 0; i< kout; i++) | |
1627 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
1628 | fprintf(stderr, "\n"); | |
1629 | #endif | |
1630 | shared_secret = BN_new(); | |
1631 | ||
1632 | BN_bin2bn(kbuf, kout, shared_secret); | |
1633 | memset(kbuf, 0, klen); | |
1634 | xfree(kbuf); | |
1635 | ||
1636 | /* XXX precompute? */ | |
fa08c86b | 1637 | key_to_blob(hostkey, &server_host_key_blob, &sbloblen); |
94ec8c6b | 1638 | |
1639 | /* calc H */ /* XXX depends on 'kex' */ | |
1640 | hash = kex_hash_gex( | |
1641 | client_version_string, | |
1642 | server_version_string, | |
1643 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
1644 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
1645 | (char *)server_host_key_blob, sbloblen, | |
1646 | nbits, dh->p, dh->g, | |
1647 | dh_client_pub, | |
1648 | dh->pub_key, | |
1649 | shared_secret | |
1650 | ); | |
1651 | buffer_free(client_kexinit); | |
1652 | buffer_free(server_kexinit); | |
1653 | xfree(client_kexinit); | |
1654 | xfree(server_kexinit); | |
1655 | #ifdef DEBUG_KEXDH | |
1656 | fprintf(stderr, "hash == "); | |
1657 | for (i = 0; i< 20; i++) | |
1658 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
1659 | fprintf(stderr, "\n"); | |
1660 | #endif | |
1661 | /* save session id := H */ | |
1662 | /* XXX hashlen depends on KEX */ | |
1663 | session_id2_len = 20; | |
1664 | session_id2 = xmalloc(session_id2_len); | |
1665 | memcpy(session_id2, hash, session_id2_len); | |
1666 | ||
1667 | /* sign H */ | |
1668 | /* XXX hashlen depends on KEX */ | |
fa08c86b | 1669 | key_sign(hostkey, &signature, &slen, hash, 20); |
94ec8c6b | 1670 | |
1671 | destroy_sensitive_data(); | |
1672 | ||
1673 | /* send server hostkey, DH pubkey 'f' and singed H */ | |
1674 | packet_start(SSH2_MSG_KEX_DH_GEX_REPLY); | |
1675 | packet_put_string((char *)server_host_key_blob, sbloblen); | |
1676 | packet_put_bignum2(dh->pub_key); /* f */ | |
1677 | packet_put_string((char *)signature, slen); | |
e78a59f5 | 1678 | packet_send(); |
94ec8c6b | 1679 | xfree(signature); |
1680 | xfree(server_host_key_blob); | |
e78a59f5 | 1681 | packet_write_wait(); |
94ec8c6b | 1682 | |
1683 | kex_derive_keys(kex, hash, shared_secret); | |
1684 | packet_set_kex(kex); | |
1685 | ||
1686 | /* have keys, free DH */ | |
1687 | DH_free(dh); | |
e78a59f5 | 1688 | } |