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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" | |
97fb6912 | 43 | RCSID("$OpenBSD: sshd.c,v 1.136 2000/12/05 16:47:28 todd 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 | ||
260d427b | 81 | #ifdef HAVE___PROGNAME |
82 | extern char *__progname; | |
83 | #else | |
84 | char *__progname; | |
85 | #endif | |
86 | ||
8efc0c15 | 87 | /* Server configuration options. */ |
88 | ServerOptions options; | |
89 | ||
90 | /* Name of the server configuration file. */ | |
91 | char *config_file_name = SERVER_CONFIG_FILE; | |
92 | ||
6ae2364d | 93 | /* |
48e671d5 | 94 | * Flag indicating whether IPv4 or IPv6. This can be set on the command line. |
95 | * Default value is AF_UNSPEC means both IPv4 and IPv6. | |
96 | */ | |
59e76f33 | 97 | #ifdef IPV4_DEFAULT |
98 | int IPv4or6 = AF_INET; | |
99 | #else | |
48e671d5 | 100 | int IPv4or6 = AF_UNSPEC; |
59e76f33 | 101 | #endif |
48e671d5 | 102 | |
5260325f | 103 | /* |
104 | * Debug mode flag. This can be set on the command line. If debug | |
105 | * mode is enabled, extra debugging output will be sent to the system | |
106 | * log, the daemon will not go to background, and will exit after processing | |
107 | * the first connection. | |
108 | */ | |
8efc0c15 | 109 | int debug_flag = 0; |
110 | ||
111 | /* Flag indicating that the daemon is being started from inetd. */ | |
112 | int inetd_flag = 0; | |
113 | ||
0b6fbf03 | 114 | /* Flag indicating that sshd should not detach and become a daemon. */ |
115 | int no_daemon_flag = 0; | |
116 | ||
6a17f9c2 | 117 | /* debug goes to stderr unless inetd_flag is set */ |
118 | int log_stderr = 0; | |
119 | ||
8efc0c15 | 120 | /* argv[0] without path. */ |
121 | char *av0; | |
122 | ||
123 | /* Saved arguments to main(). */ | |
124 | char **saved_argv; | |
4d33e531 | 125 | int saved_argc; |
8efc0c15 | 126 | |
aa3378df | 127 | /* |
48e671d5 | 128 | * The sockets that the server is listening; this is used in the SIGHUP |
129 | * signal handler. | |
aa3378df | 130 | */ |
48e671d5 | 131 | #define MAX_LISTEN_SOCKS 16 |
132 | int listen_socks[MAX_LISTEN_SOCKS]; | |
133 | int num_listen_socks = 0; | |
8efc0c15 | 134 | |
aa3378df | 135 | /* |
136 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
137 | * sshd will skip the version-number exchange | |
138 | */ | |
5260325f | 139 | char *client_version_string = NULL; |
7368a6c8 | 140 | char *server_version_string = NULL; |
8efc0c15 | 141 | |
aa3378df | 142 | /* |
143 | * Any really sensitive data in the application is contained in this | |
144 | * structure. The idea is that this structure could be locked into memory so | |
145 | * that the pages do not get written into swap. However, there are some | |
146 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
147 | * have access to the internals of them, and locking just the structure is | |
148 | * not very useful. Currently, memory locking is not implemented. | |
149 | */ | |
5260325f | 150 | struct { |
fa08c86b | 151 | Key *server_key; /* empheral server key */ |
152 | Key *ssh1_host_key; /* ssh1 host key */ | |
153 | Key **host_keys; /* all private host keys */ | |
154 | int have_ssh1_key; | |
155 | int have_ssh2_key; | |
8efc0c15 | 156 | } sensitive_data; |
157 | ||
aa3378df | 158 | /* |
159 | * Flag indicating whether the current session key has been used. This flag | |
160 | * is set whenever the key is used, and cleared when the key is regenerated. | |
161 | */ | |
8efc0c15 | 162 | int key_used = 0; |
163 | ||
164 | /* This is set to true when SIGHUP is received. */ | |
165 | int received_sighup = 0; | |
166 | ||
7368a6c8 | 167 | /* session identifier, used by RSA-auth */ |
168 | unsigned char session_id[16]; | |
e7c0f9d5 | 169 | |
a306f2dd | 170 | /* same for ssh2 */ |
171 | unsigned char *session_id2 = NULL; | |
172 | int session_id2_len = 0; | |
173 | ||
c345cf9d | 174 | /* record remote hostname or ip */ |
175 | unsigned int utmp_len = MAXHOSTNAMELEN; | |
176 | ||
7368a6c8 | 177 | /* Prototypes for various functions defined later in this file. */ |
178 | void do_ssh1_kex(); | |
e78a59f5 | 179 | void do_ssh2_kex(); |
c8d54615 | 180 | |
94ec8c6b | 181 | void ssh_dh1_server(Kex *, Buffer *_kexinit, Buffer *); |
182 | void ssh_dhgex_server(Kex *, Buffer *_kexinit, Buffer *); | |
183 | ||
48e671d5 | 184 | /* |
185 | * Close all listening sockets | |
186 | */ | |
187 | void | |
188 | close_listen_socks(void) | |
189 | { | |
190 | int i; | |
191 | for (i = 0; i < num_listen_socks; i++) | |
192 | close(listen_socks[i]); | |
193 | num_listen_socks = -1; | |
194 | } | |
195 | ||
5260325f | 196 | /* |
197 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
198 | * the effect is to reread the configuration file (and to regenerate | |
199 | * the server key). | |
200 | */ | |
6ae2364d | 201 | void |
5260325f | 202 | sighup_handler(int sig) |
8efc0c15 | 203 | { |
5260325f | 204 | received_sighup = 1; |
205 | signal(SIGHUP, sighup_handler); | |
8efc0c15 | 206 | } |
207 | ||
5260325f | 208 | /* |
209 | * Called from the main program after receiving SIGHUP. | |
210 | * Restarts the server. | |
211 | */ | |
6ae2364d | 212 | void |
5260325f | 213 | sighup_restart() |
8efc0c15 | 214 | { |
5260325f | 215 | log("Received SIGHUP; restarting."); |
48e671d5 | 216 | close_listen_socks(); |
5260325f | 217 | execv(saved_argv[0], saved_argv); |
218 | log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno)); | |
219 | exit(1); | |
8efc0c15 | 220 | } |
221 | ||
5260325f | 222 | /* |
223 | * Generic signal handler for terminating signals in the master daemon. | |
224 | * These close the listen socket; not closing it seems to cause "Address | |
225 | * already in use" problems on some machines, which is inconvenient. | |
226 | */ | |
6ae2364d | 227 | void |
5260325f | 228 | sigterm_handler(int sig) |
8efc0c15 | 229 | { |
5260325f | 230 | log("Received signal %d; terminating.", sig); |
48e671d5 | 231 | close_listen_socks(); |
0fbe8c74 | 232 | unlink(options.pid_file); |
5260325f | 233 | exit(255); |
8efc0c15 | 234 | } |
235 | ||
5260325f | 236 | /* |
237 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
238 | * reap any zombies left by exited c. | |
239 | */ | |
6ae2364d | 240 | void |
5260325f | 241 | main_sigchld_handler(int sig) |
8efc0c15 | 242 | { |
5260325f | 243 | int save_errno = errno; |
244 | int status; | |
5ad13cd7 | 245 | |
5260325f | 246 | while (waitpid(-1, &status, WNOHANG) > 0) |
247 | ; | |
5ad13cd7 | 248 | |
5260325f | 249 | signal(SIGCHLD, main_sigchld_handler); |
250 | errno = save_errno; | |
8efc0c15 | 251 | } |
252 | ||
5260325f | 253 | /* |
254 | * Signal handler for the alarm after the login grace period has expired. | |
255 | */ | |
6ae2364d | 256 | void |
5260325f | 257 | grace_alarm_handler(int sig) |
8efc0c15 | 258 | { |
5260325f | 259 | /* Close the connection. */ |
260 | packet_close(); | |
8efc0c15 | 261 | |
5260325f | 262 | /* Log error and exit. */ |
263 | fatal("Timeout before authentication for %s.", get_remote_ipaddr()); | |
264 | } | |
8efc0c15 | 265 | |
5260325f | 266 | /* |
267 | * Signal handler for the key regeneration alarm. Note that this | |
268 | * alarm only occurs in the daemon waiting for connections, and it does not | |
269 | * do anything with the private key or random state before forking. | |
270 | * Thus there should be no concurrency control/asynchronous execution | |
271 | * problems. | |
272 | */ | |
a306f2dd | 273 | /* XXX do we really want this work to be done in a signal handler ? -m */ |
6ae2364d | 274 | void |
fa08c86b | 275 | generate_empheral_server_key(void) |
276 | { | |
277 | log("Generating %s%d bit RSA key.", sensitive_data.server_key ? "new " : "", | |
278 | options.server_key_bits); | |
279 | if (sensitive_data.server_key != NULL) | |
280 | key_free(sensitive_data.server_key); | |
281 | sensitive_data.server_key = key_generate(KEY_RSA1, options.server_key_bits); | |
282 | arc4random_stir(); | |
283 | log("RSA key generation complete."); | |
284 | } | |
285 | void | |
5260325f | 286 | key_regeneration_alarm(int sig) |
287 | { | |
288 | int save_errno = errno; | |
289 | ||
290 | /* Check if we should generate a new key. */ | |
291 | if (key_used) { | |
292 | /* This should really be done in the background. */ | |
fa08c86b | 293 | generate_empheral_server_key(); |
5260325f | 294 | key_used = 0; |
5260325f | 295 | } |
296 | /* Reschedule the alarm. */ | |
297 | signal(SIGALRM, key_regeneration_alarm); | |
298 | alarm(options.key_regeneration_time); | |
299 | errno = save_errno; | |
300 | } | |
8efc0c15 | 301 | |
7368a6c8 | 302 | void |
303 | sshd_exchange_identification(int sock_in, int sock_out) | |
304 | { | |
a8be9f80 | 305 | int i, mismatch; |
7368a6c8 | 306 | int remote_major, remote_minor; |
a8be9f80 | 307 | int major, minor; |
7368a6c8 | 308 | char *s; |
309 | char buf[256]; /* Must not be larger than remote_version. */ | |
310 | char remote_version[256]; /* Must be at least as big as buf. */ | |
311 | ||
a8be9f80 | 312 | if ((options.protocol & SSH_PROTO_1) && |
313 | (options.protocol & SSH_PROTO_2)) { | |
314 | major = PROTOCOL_MAJOR_1; | |
315 | minor = 99; | |
316 | } else if (options.protocol & SSH_PROTO_2) { | |
317 | major = PROTOCOL_MAJOR_2; | |
318 | minor = PROTOCOL_MINOR_2; | |
319 | } else { | |
320 | major = PROTOCOL_MAJOR_1; | |
321 | minor = PROTOCOL_MINOR_1; | |
322 | } | |
323 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
7368a6c8 | 324 | server_version_string = xstrdup(buf); |
325 | ||
326 | if (client_version_string == NULL) { | |
327 | /* Send our protocol version identification. */ | |
328 | if (atomicio(write, sock_out, server_version_string, strlen(server_version_string)) | |
329 | != strlen(server_version_string)) { | |
330 | log("Could not write ident string to %s.", get_remote_ipaddr()); | |
331 | fatal_cleanup(); | |
332 | } | |
333 | ||
334 | /* Read other side\'s version identification. */ | |
335 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
e5a0294f | 336 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { |
7368a6c8 | 337 | log("Did not receive ident string from %s.", get_remote_ipaddr()); |
338 | fatal_cleanup(); | |
339 | } | |
340 | if (buf[i] == '\r') { | |
341 | buf[i] = '\n'; | |
342 | buf[i + 1] = 0; | |
94ec8c6b | 343 | /* Kludge for F-Secure Macintosh < 1.0.2 */ |
344 | if (i == 12 && | |
345 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
346 | break; | |
7368a6c8 | 347 | continue; |
7368a6c8 | 348 | } |
349 | if (buf[i] == '\n') { | |
350 | /* buf[i] == '\n' */ | |
351 | buf[i + 1] = 0; | |
352 | break; | |
353 | } | |
354 | } | |
355 | buf[sizeof(buf) - 1] = 0; | |
356 | client_version_string = xstrdup(buf); | |
357 | } | |
358 | ||
359 | /* | |
360 | * Check that the versions match. In future this might accept | |
361 | * several versions and set appropriate flags to handle them. | |
362 | */ | |
363 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
364 | &remote_major, &remote_minor, remote_version) != 3) { | |
6ae2364d | 365 | s = "Protocol mismatch.\n"; |
7368a6c8 | 366 | (void) atomicio(write, sock_out, s, strlen(s)); |
367 | close(sock_in); | |
368 | close(sock_out); | |
369 | log("Bad protocol version identification '%.100s' from %s", | |
370 | client_version_string, get_remote_ipaddr()); | |
371 | fatal_cleanup(); | |
372 | } | |
373 | debug("Client protocol version %d.%d; client software version %.100s", | |
374 | remote_major, remote_minor, remote_version); | |
375 | ||
e78a59f5 | 376 | compat_datafellows(remote_version); |
377 | ||
a8be9f80 | 378 | mismatch = 0; |
7368a6c8 | 379 | switch(remote_major) { |
380 | case 1: | |
a306f2dd | 381 | if (remote_minor == 99) { |
382 | if (options.protocol & SSH_PROTO_2) | |
383 | enable_compat20(); | |
384 | else | |
385 | mismatch = 1; | |
386 | break; | |
387 | } | |
a8be9f80 | 388 | if (!(options.protocol & SSH_PROTO_1)) { |
389 | mismatch = 1; | |
390 | break; | |
391 | } | |
7368a6c8 | 392 | if (remote_minor < 3) { |
089fbbd2 | 393 | packet_disconnect("Your ssh version is too old and " |
7368a6c8 | 394 | "is no longer supported. Please install a newer version."); |
395 | } else if (remote_minor == 3) { | |
396 | /* note that this disables agent-forwarding */ | |
397 | enable_compat13(); | |
398 | } | |
a8be9f80 | 399 | break; |
e78a59f5 | 400 | case 2: |
a8be9f80 | 401 | if (options.protocol & SSH_PROTO_2) { |
e78a59f5 | 402 | enable_compat20(); |
403 | break; | |
404 | } | |
405 | /* FALLTHROUGH */ | |
6ae2364d | 406 | default: |
a8be9f80 | 407 | mismatch = 1; |
408 | break; | |
409 | } | |
410 | chop(server_version_string); | |
411 | chop(client_version_string); | |
412 | debug("Local version string %.200s", server_version_string); | |
413 | ||
414 | if (mismatch) { | |
7368a6c8 | 415 | s = "Protocol major versions differ.\n"; |
416 | (void) atomicio(write, sock_out, s, strlen(s)); | |
417 | close(sock_in); | |
418 | close(sock_out); | |
a8be9f80 | 419 | log("Protocol major versions differ for %s: %.200s vs. %.200s", |
420 | get_remote_ipaddr(), | |
421 | server_version_string, client_version_string); | |
7368a6c8 | 422 | fatal_cleanup(); |
7368a6c8 | 423 | } |
a306f2dd | 424 | if (compat20) |
425 | packet_set_ssh2_format(); | |
426 | } | |
427 | ||
428 | ||
fa08c86b | 429 | /* Destroy the host and server keys. They will no longer be needed. */ |
a306f2dd | 430 | void |
431 | destroy_sensitive_data(void) | |
432 | { | |
fa08c86b | 433 | int i; |
434 | ||
435 | if (sensitive_data.server_key) { | |
436 | key_free(sensitive_data.server_key); | |
437 | sensitive_data.server_key = NULL; | |
438 | } | |
439 | for(i = 0; i < options.num_host_key_files; i++) { | |
440 | if (sensitive_data.host_keys[i]) { | |
441 | key_free(sensitive_data.host_keys[i]); | |
442 | sensitive_data.host_keys[i] = NULL; | |
443 | } | |
444 | } | |
445 | sensitive_data.ssh1_host_key = NULL; | |
446 | } | |
447 | Key * | |
448 | load_private_key_autodetect(const char *filename) | |
449 | { | |
450 | struct stat st; | |
451 | int type; | |
452 | Key *public, *private; | |
453 | ||
454 | if (stat(filename, &st) < 0) { | |
455 | perror(filename); | |
456 | return NULL; | |
457 | } | |
458 | /* | |
459 | * try to load the public key. right now this only works for RSA1, | |
460 | * since SSH2 keys are fully encrypted | |
461 | */ | |
462 | type = KEY_RSA1; | |
463 | public = key_new(type); | |
464 | if (!load_public_key(filename, public, NULL)) { | |
465 | /* ok, so we will assume this is 'some' key */ | |
466 | type = KEY_UNSPEC; | |
467 | } | |
468 | key_free(public); | |
469 | ||
470 | /* Ok, try key with empty passphrase */ | |
471 | private = key_new(type); | |
472 | if (load_private_key(filename, "", private, NULL)) { | |
473 | debug("load_private_key_autodetect: type %d %s", | |
474 | private->type, key_type(private)); | |
475 | return private; | |
476 | } | |
477 | key_free(private); | |
478 | return NULL; | |
479 | } | |
480 | ||
481 | char * | |
482 | list_hostkey_types(void) | |
483 | { | |
484 | static char buf[1024]; | |
485 | int i; | |
486 | buf[0] = '\0'; | |
487 | for(i = 0; i < options.num_host_key_files; i++) { | |
488 | Key *key = sensitive_data.host_keys[i]; | |
489 | if (key == NULL) | |
490 | continue; | |
491 | switch(key->type) { | |
492 | case KEY_RSA: | |
493 | case KEY_DSA: | |
494 | strlcat(buf, key_ssh_name(key), sizeof buf); | |
495 | strlcat(buf, ",", sizeof buf); | |
496 | break; | |
497 | } | |
498 | } | |
499 | i = strlen(buf); | |
500 | if (i > 0 && buf[i-1] == ',') | |
501 | buf[i-1] = '\0'; | |
502 | debug("list_hostkey_types: %s", buf); | |
503 | return buf; | |
504 | } | |
505 | ||
506 | Key * | |
507 | get_hostkey_by_type(int type) | |
508 | { | |
509 | int i; | |
510 | for(i = 0; i < options.num_host_key_files; i++) { | |
511 | Key *key = sensitive_data.host_keys[i]; | |
512 | if (key != NULL && key->type == type) | |
513 | return key; | |
514 | } | |
515 | return NULL; | |
7368a6c8 | 516 | } |
517 | ||
c345cf9d | 518 | /* |
519 | * returns 1 if connection should be dropped, 0 otherwise. | |
520 | * dropping starts at connection #max_startups_begin with a probability | |
521 | * of (max_startups_rate/100). the probability increases linearly until | |
522 | * all connections are dropped for startups > max_startups | |
523 | */ | |
524 | int | |
525 | drop_connection(int startups) | |
526 | { | |
527 | double p, r; | |
528 | ||
529 | if (startups < options.max_startups_begin) | |
530 | return 0; | |
531 | if (startups >= options.max_startups) | |
532 | return 1; | |
533 | if (options.max_startups_rate == 100) | |
534 | return 1; | |
535 | ||
536 | p = 100 - options.max_startups_rate; | |
537 | p *= startups - options.max_startups_begin; | |
538 | p /= (double) (options.max_startups - options.max_startups_begin); | |
539 | p += options.max_startups_rate; | |
540 | p /= 100.0; | |
541 | r = arc4random() / (double) UINT_MAX; | |
542 | ||
543 | debug("drop_connection: p %g, r %g", p, r); | |
544 | return (r < p) ? 1 : 0; | |
545 | } | |
546 | ||
089fbbd2 | 547 | int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */ |
548 | int startup_pipe; /* in child */ | |
549 | ||
5260325f | 550 | /* |
551 | * Main program for the daemon. | |
552 | */ | |
8efc0c15 | 553 | int |
554 | main(int ac, char **av) | |
555 | { | |
5260325f | 556 | extern char *optarg; |
557 | extern int optind; | |
089fbbd2 | 558 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; |
9da5c3c9 | 559 | pid_t pid; |
48e671d5 | 560 | socklen_t fromlen; |
a306f2dd | 561 | int silent = 0; |
48e671d5 | 562 | fd_set *fdset; |
563 | struct sockaddr_storage from; | |
5260325f | 564 | const char *remote_ip; |
565 | int remote_port; | |
5260325f | 566 | FILE *f; |
567 | struct linger linger; | |
48e671d5 | 568 | struct addrinfo *ai; |
569 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
570 | int listen_sock, maxfd; | |
089fbbd2 | 571 | int startup_p[2]; |
572 | int startups = 0; | |
5260325f | 573 | |
260d427b | 574 | __progname = get_progname(av[0]); |
264dce47 | 575 | init_rng(); |
576 | ||
5260325f | 577 | /* Save argv[0]. */ |
4d33e531 | 578 | saved_argc = ac; |
5260325f | 579 | saved_argv = av; |
580 | if (strchr(av[0], '/')) | |
581 | av0 = strrchr(av[0], '/') + 1; | |
582 | else | |
583 | av0 = av[0]; | |
584 | ||
585 | /* Initialize configuration options to their default values. */ | |
586 | initialize_server_options(&options); | |
587 | ||
588 | /* Parse command-line arguments. */ | |
0b6fbf03 | 589 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:dDiqQ46")) != EOF) { |
5260325f | 590 | switch (opt) { |
48e671d5 | 591 | case '4': |
592 | IPv4or6 = AF_INET; | |
593 | break; | |
594 | case '6': | |
595 | IPv4or6 = AF_INET6; | |
596 | break; | |
5260325f | 597 | case 'f': |
598 | config_file_name = optarg; | |
599 | break; | |
600 | case 'd': | |
bcbf86ec | 601 | if (0 == debug_flag) { |
602 | debug_flag = 1; | |
603 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
604 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
605 | options.log_level++; | |
606 | } else { | |
607 | fprintf(stderr, "Too high debugging level.\n"); | |
608 | exit(1); | |
609 | } | |
5260325f | 610 | break; |
0b6fbf03 | 611 | case 'D': |
612 | no_daemon_flag = 1; | |
613 | break; | |
5260325f | 614 | case 'i': |
615 | inetd_flag = 1; | |
616 | break; | |
617 | case 'Q': | |
a306f2dd | 618 | silent = 1; |
5260325f | 619 | break; |
620 | case 'q': | |
621 | options.log_level = SYSLOG_LEVEL_QUIET; | |
622 | break; | |
623 | case 'b': | |
624 | options.server_key_bits = atoi(optarg); | |
625 | break; | |
626 | case 'p': | |
48e671d5 | 627 | options.ports_from_cmdline = 1; |
bcbf86ec | 628 | if (options.num_ports >= MAX_PORTS) { |
629 | fprintf(stderr, "too many ports.\n"); | |
630 | exit(1); | |
631 | } | |
48e671d5 | 632 | options.ports[options.num_ports++] = atoi(optarg); |
5260325f | 633 | break; |
634 | case 'g': | |
635 | options.login_grace_time = atoi(optarg); | |
636 | break; | |
637 | case 'k': | |
638 | options.key_regeneration_time = atoi(optarg); | |
639 | break; | |
640 | case 'h': | |
fa08c86b | 641 | if (options.num_host_key_files >= MAX_HOSTKEYS) { |
642 | fprintf(stderr, "too many host keys.\n"); | |
643 | exit(1); | |
644 | } | |
645 | options.host_key_files[options.num_host_key_files++] = optarg; | |
5260325f | 646 | break; |
647 | case 'V': | |
648 | client_version_string = optarg; | |
649 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
650 | inetd_flag = 1; | |
651 | break; | |
c345cf9d | 652 | case 'u': |
653 | utmp_len = atoi(optarg); | |
654 | break; | |
5260325f | 655 | case '?': |
656 | default: | |
657 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
658 | fprintf(stderr, "Usage: %s [options]\n", av0); | |
659 | fprintf(stderr, "Options:\n"); | |
aa3378df | 660 | fprintf(stderr, " -f file Configuration file (default %s)\n", SERVER_CONFIG_FILE); |
bcbf86ec | 661 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); |
5260325f | 662 | fprintf(stderr, " -i Started from inetd\n"); |
663 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
664 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
665 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
666 | fprintf(stderr, " -g seconds Grace period for authentication (default: 300)\n"); | |
667 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
668 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
48e671d5 | 669 | HOST_KEY_FILE); |
c345cf9d | 670 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); |
48e671d5 | 671 | fprintf(stderr, " -4 Use IPv4 only\n"); |
672 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
5260325f | 673 | exit(1); |
674 | } | |
675 | } | |
676 | ||
48e671d5 | 677 | /* |
678 | * Force logging to stderr until we have loaded the private host | |
679 | * key (unless started from inetd) | |
680 | */ | |
681 | log_init(av0, | |
682 | options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level, | |
683 | options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility, | |
a306f2dd | 684 | !silent && !inetd_flag); |
48e671d5 | 685 | |
5260325f | 686 | /* Read server configuration options from the configuration file. */ |
687 | read_server_config(&options, config_file_name); | |
688 | ||
689 | /* Fill in default values for those options not explicitly set. */ | |
690 | fill_default_server_options(&options); | |
691 | ||
5260325f | 692 | /* Check that there are no remaining arguments. */ |
693 | if (optind < ac) { | |
694 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
695 | exit(1); | |
8efc0c15 | 696 | } |
5260325f | 697 | |
698 | debug("sshd version %.100s", SSH_VERSION); | |
699 | ||
fa08c86b | 700 | /* load private host keys */ |
701 | sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*)); | |
702 | sensitive_data.server_key = NULL; | |
703 | sensitive_data.ssh1_host_key = NULL; | |
704 | sensitive_data.have_ssh1_key = 0; | |
705 | sensitive_data.have_ssh2_key = 0; | |
a306f2dd | 706 | |
fa08c86b | 707 | for(i = 0; i < options.num_host_key_files; i++) { |
708 | Key *key = load_private_key_autodetect(options.host_key_files[i]); | |
709 | if (key == NULL) { | |
a306f2dd | 710 | error("Could not load host key: %.200s: %.100s", |
fa08c86b | 711 | options.host_key_files[i], strerror(errno)); |
712 | continue; | |
a306f2dd | 713 | } |
fa08c86b | 714 | switch(key->type){ |
715 | case KEY_RSA1: | |
716 | sensitive_data.ssh1_host_key = key; | |
717 | sensitive_data.have_ssh1_key = 1; | |
718 | break; | |
719 | case KEY_RSA: | |
720 | case KEY_DSA: | |
721 | sensitive_data.have_ssh2_key = 1; | |
722 | break; | |
a306f2dd | 723 | } |
fa08c86b | 724 | sensitive_data.host_keys[i] = key; |
725 | } | |
726 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
727 | log("Disabling protocol version 1. Could not load host key"); | |
728 | options.protocol &= ~SSH_PROTO_1; | |
729 | } | |
730 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
731 | log("Disabling protocol version 2. Could not load host key"); | |
732 | options.protocol &= ~SSH_PROTO_2; | |
a306f2dd | 733 | } |
734 | if (! options.protocol & (SSH_PROTO_1|SSH_PROTO_2)) { | |
735 | if (silent == 0) | |
736 | fprintf(stderr, "sshd: no hostkeys available -- exiting.\n"); | |
737 | log("sshd: no hostkeys available -- exiting.\n"); | |
5260325f | 738 | exit(1); |
739 | } | |
5260325f | 740 | |
a306f2dd | 741 | /* Check certain values for sanity. */ |
742 | if (options.protocol & SSH_PROTO_1) { | |
743 | if (options.server_key_bits < 512 || | |
744 | options.server_key_bits > 32768) { | |
745 | fprintf(stderr, "Bad server key size.\n"); | |
746 | exit(1); | |
747 | } | |
748 | /* | |
749 | * Check that server and host key lengths differ sufficiently. This | |
750 | * is necessary to make double encryption work with rsaref. Oh, I | |
751 | * hate software patents. I dont know if this can go? Niels | |
752 | */ | |
753 | if (options.server_key_bits > | |
fa08c86b | 754 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED && |
a306f2dd | 755 | options.server_key_bits < |
fa08c86b | 756 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { |
a306f2dd | 757 | options.server_key_bits = |
fa08c86b | 758 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED; |
a306f2dd | 759 | debug("Forcing server key to %d bits to make it differ from host key.", |
760 | options.server_key_bits); | |
761 | } | |
762 | } | |
763 | ||
77bb0bca | 764 | #ifdef HAVE_SCO_PROTECTED_PW |
765 | (void) set_auth_parameters(ac, av); | |
766 | #endif | |
767 | ||
a306f2dd | 768 | /* Initialize the log (it is reinitialized below in case we forked). */ |
5260325f | 769 | if (debug_flag && !inetd_flag) |
770 | log_stderr = 1; | |
771 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
772 | ||
a306f2dd | 773 | /* |
774 | * If not in debugging mode, and not started from inetd, disconnect | |
775 | * from the controlling terminal, and fork. The original process | |
776 | * exits. | |
777 | */ | |
0b6fbf03 | 778 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { |
8efc0c15 | 779 | #ifdef TIOCNOTTY |
5260325f | 780 | int fd; |
8efc0c15 | 781 | #endif /* TIOCNOTTY */ |
5260325f | 782 | if (daemon(0, 0) < 0) |
783 | fatal("daemon() failed: %.200s", strerror(errno)); | |
784 | ||
785 | /* Disconnect from the controlling tty. */ | |
8efc0c15 | 786 | #ifdef TIOCNOTTY |
5260325f | 787 | fd = open("/dev/tty", O_RDWR | O_NOCTTY); |
788 | if (fd >= 0) { | |
789 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
790 | close(fd); | |
791 | } | |
8efc0c15 | 792 | #endif /* TIOCNOTTY */ |
8efc0c15 | 793 | } |
5260325f | 794 | /* Reinitialize the log (because of the fork above). */ |
795 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
796 | ||
5260325f | 797 | /* Initialize the random number generator. */ |
798 | arc4random_stir(); | |
799 | ||
800 | /* Chdir to the root directory so that the current disk can be | |
801 | unmounted if desired. */ | |
802 | chdir("/"); | |
803 | ||
5260325f | 804 | /* Start listening for a socket, unless started from inetd. */ |
805 | if (inetd_flag) { | |
806 | int s1, s2; | |
807 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ | |
808 | s2 = dup(s1); | |
809 | sock_in = dup(0); | |
810 | sock_out = dup(1); | |
4c8722d9 | 811 | startup_pipe = -1; |
a306f2dd | 812 | /* |
813 | * We intentionally do not close the descriptors 0, 1, and 2 | |
814 | * as our code for setting the descriptors won\'t work if | |
815 | * ttyfd happens to be one of those. | |
816 | */ | |
5260325f | 817 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); |
fa08c86b | 818 | if (options.protocol & SSH_PROTO_1) |
819 | generate_empheral_server_key(); | |
5260325f | 820 | } else { |
48e671d5 | 821 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
822 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
823 | continue; | |
824 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
825 | fatal("Too many listen sockets. " | |
826 | "Enlarge MAX_LISTEN_SOCKS"); | |
827 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
828 | ntop, sizeof(ntop), strport, sizeof(strport), | |
829 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
830 | error("getnameinfo failed"); | |
831 | continue; | |
832 | } | |
833 | /* Create socket for listening. */ | |
834 | listen_sock = socket(ai->ai_family, SOCK_STREAM, 0); | |
835 | if (listen_sock < 0) { | |
836 | /* kernel may not support ipv6 */ | |
837 | verbose("socket: %.100s", strerror(errno)); | |
838 | continue; | |
839 | } | |
840 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
841 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
842 | close(listen_sock); | |
843 | continue; | |
844 | } | |
845 | /* | |
846 | * Set socket options. We try to make the port | |
847 | * reusable and have it close as fast as possible | |
848 | * without waiting in unnecessary wait states on | |
849 | * close. | |
850 | */ | |
851 | setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, | |
852 | (void *) &on, sizeof(on)); | |
853 | linger.l_onoff = 1; | |
854 | linger.l_linger = 5; | |
855 | setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, | |
856 | (void *) &linger, sizeof(linger)); | |
857 | ||
858 | debug("Bind to port %s on %s.", strport, ntop); | |
859 | ||
860 | /* Bind the socket to the desired port. */ | |
16218745 | 861 | if ((bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) && |
862 | (!ai->ai_next)) { | |
48e671d5 | 863 | error("Bind to port %s on %s failed: %.200s.", |
864 | strport, ntop, strerror(errno)); | |
865 | close(listen_sock); | |
866 | continue; | |
867 | } | |
868 | listen_socks[num_listen_socks] = listen_sock; | |
869 | num_listen_socks++; | |
870 | ||
871 | /* Start listening on the port. */ | |
872 | log("Server listening on %s port %s.", ntop, strport); | |
873 | if (listen(listen_sock, 5) < 0) | |
874 | fatal("listen: %.100s", strerror(errno)); | |
875 | ||
5260325f | 876 | } |
48e671d5 | 877 | freeaddrinfo(options.listen_addrs); |
878 | ||
879 | if (!num_listen_socks) | |
880 | fatal("Cannot bind any address."); | |
881 | ||
5260325f | 882 | if (!debug_flag) { |
aa3378df | 883 | /* |
97fb6912 | 884 | * Record our pid in /var/run/sshd.pid to make it |
885 | * easier to kill the correct sshd. We don't want to | |
886 | * do this before the bind above because the bind will | |
aa3378df | 887 | * fail if there already is a daemon, and this will |
888 | * overwrite any old pid in the file. | |
889 | */ | |
3c62e7eb | 890 | f = fopen(options.pid_file, "wb"); |
5260325f | 891 | if (f) { |
892 | fprintf(f, "%u\n", (unsigned int) getpid()); | |
893 | fclose(f); | |
894 | } | |
8efc0c15 | 895 | } |
a306f2dd | 896 | if (options.protocol & SSH_PROTO_1) { |
fa08c86b | 897 | generate_empheral_server_key(); |
5260325f | 898 | |
a306f2dd | 899 | /* Schedule server key regeneration alarm. */ |
900 | signal(SIGALRM, key_regeneration_alarm); | |
901 | alarm(options.key_regeneration_time); | |
902 | } | |
5260325f | 903 | |
904 | /* Arrange to restart on SIGHUP. The handler needs listen_sock. */ | |
905 | signal(SIGHUP, sighup_handler); | |
089fbbd2 | 906 | |
5260325f | 907 | signal(SIGTERM, sigterm_handler); |
908 | signal(SIGQUIT, sigterm_handler); | |
909 | ||
910 | /* Arrange SIGCHLD to be caught. */ | |
911 | signal(SIGCHLD, main_sigchld_handler); | |
912 | ||
48e671d5 | 913 | /* setup fd set for listen */ |
089fbbd2 | 914 | fdset = NULL; |
48e671d5 | 915 | maxfd = 0; |
916 | for (i = 0; i < num_listen_socks; i++) | |
917 | if (listen_socks[i] > maxfd) | |
918 | maxfd = listen_socks[i]; | |
089fbbd2 | 919 | /* pipes connected to unauthenticated childs */ |
920 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
921 | for (i = 0; i < options.max_startups; i++) | |
922 | startup_pipes[i] = -1; | |
48e671d5 | 923 | |
aa3378df | 924 | /* |
925 | * Stay listening for connections until the system crashes or | |
926 | * the daemon is killed with a signal. | |
927 | */ | |
5260325f | 928 | for (;;) { |
929 | if (received_sighup) | |
930 | sighup_restart(); | |
089fbbd2 | 931 | if (fdset != NULL) |
932 | xfree(fdset); | |
933 | fdsetsz = howmany(maxfd, NFDBITS) * sizeof(fd_mask); | |
934 | fdset = (fd_set *)xmalloc(fdsetsz); | |
48e671d5 | 935 | memset(fdset, 0, fdsetsz); |
089fbbd2 | 936 | |
48e671d5 | 937 | for (i = 0; i < num_listen_socks; i++) |
938 | FD_SET(listen_socks[i], fdset); | |
089fbbd2 | 939 | for (i = 0; i < options.max_startups; i++) |
940 | if (startup_pipes[i] != -1) | |
941 | FD_SET(startup_pipes[i], fdset); | |
942 | ||
943 | /* Wait in select until there is a connection. */ | |
48e671d5 | 944 | if (select(maxfd + 1, fdset, NULL, NULL, NULL) < 0) { |
945 | if (errno != EINTR) | |
946 | error("select: %.100s", strerror(errno)); | |
2d86a6cc | 947 | continue; |
48e671d5 | 948 | } |
089fbbd2 | 949 | for (i = 0; i < options.max_startups; i++) |
950 | if (startup_pipes[i] != -1 && | |
951 | FD_ISSET(startup_pipes[i], fdset)) { | |
952 | /* | |
953 | * the read end of the pipe is ready | |
954 | * if the child has closed the pipe | |
955 | * after successfull authentication | |
956 | * or if the child has died | |
957 | */ | |
958 | close(startup_pipes[i]); | |
959 | startup_pipes[i] = -1; | |
960 | startups--; | |
961 | } | |
48e671d5 | 962 | for (i = 0; i < num_listen_socks; i++) { |
963 | if (!FD_ISSET(listen_socks[i], fdset)) | |
5260325f | 964 | continue; |
089fbbd2 | 965 | fromlen = sizeof(from); |
966 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
967 | &fromlen); | |
968 | if (newsock < 0) { | |
969 | if (errno != EINTR && errno != EWOULDBLOCK) | |
970 | error("accept: %.100s", strerror(errno)); | |
971 | continue; | |
972 | } | |
973 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
974 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
975 | continue; | |
976 | } | |
c345cf9d | 977 | if (drop_connection(startups) == 1) { |
978 | debug("drop connection #%d", startups); | |
089fbbd2 | 979 | close(newsock); |
980 | continue; | |
981 | } | |
982 | if (pipe(startup_p) == -1) { | |
983 | close(newsock); | |
984 | continue; | |
985 | } | |
986 | ||
987 | for (j = 0; j < options.max_startups; j++) | |
988 | if (startup_pipes[j] == -1) { | |
989 | startup_pipes[j] = startup_p[0]; | |
990 | if (maxfd < startup_p[0]) | |
991 | maxfd = startup_p[0]; | |
992 | startups++; | |
993 | break; | |
994 | } | |
995 | ||
aa3378df | 996 | /* |
089fbbd2 | 997 | * Got connection. Fork a child to handle it, unless |
998 | * we are in debugging mode. | |
aa3378df | 999 | */ |
089fbbd2 | 1000 | if (debug_flag) { |
aa3378df | 1001 | /* |
089fbbd2 | 1002 | * In debugging mode. Close the listening |
1003 | * socket, and start processing the | |
1004 | * connection without forking. | |
aa3378df | 1005 | */ |
089fbbd2 | 1006 | debug("Server will not fork when running in debugging mode."); |
48e671d5 | 1007 | close_listen_socks(); |
5260325f | 1008 | sock_in = newsock; |
1009 | sock_out = newsock; | |
5540ea9b | 1010 | startup_pipe = -1; |
3f7a7e4a | 1011 | pid = getpid(); |
5260325f | 1012 | break; |
089fbbd2 | 1013 | } else { |
1014 | /* | |
1015 | * Normal production daemon. Fork, and have | |
1016 | * the child process the connection. The | |
1017 | * parent continues listening. | |
1018 | */ | |
1019 | if ((pid = fork()) == 0) { | |
1020 | /* | |
1021 | * Child. Close the listening and max_startup | |
1022 | * sockets. Start using the accepted socket. | |
1023 | * Reinitialize logging (since our pid has | |
1024 | * changed). We break out of the loop to handle | |
1025 | * the connection. | |
1026 | */ | |
1027 | startup_pipe = startup_p[1]; | |
1028 | for (j = 0; j < options.max_startups; j++) | |
1029 | if (startup_pipes[j] != -1) | |
1030 | close(startup_pipes[j]); | |
1031 | close_listen_socks(); | |
1032 | sock_in = newsock; | |
1033 | sock_out = newsock; | |
1034 | log_init(av0, options.log_level, options.log_facility, log_stderr); | |
1035 | break; | |
1036 | } | |
5260325f | 1037 | } |
5260325f | 1038 | |
089fbbd2 | 1039 | /* Parent. Stay in the loop. */ |
1040 | if (pid < 0) | |
1041 | error("fork: %.100s", strerror(errno)); | |
1042 | else | |
1043 | debug("Forked child %d.", pid); | |
5260325f | 1044 | |
089fbbd2 | 1045 | close(startup_p[1]); |
5260325f | 1046 | |
089fbbd2 | 1047 | /* Mark that the key has been used (it was "given" to the child). */ |
1048 | key_used = 1; | |
5260325f | 1049 | |
089fbbd2 | 1050 | arc4random_stir(); |
1051 | ||
1052 | /* Close the new socket (the child is now taking care of it). */ | |
1053 | close(newsock); | |
1054 | } | |
48e671d5 | 1055 | /* child process check (or debug mode) */ |
1056 | if (num_listen_socks < 0) | |
1057 | break; | |
5260325f | 1058 | } |
1059 | } | |
8efc0c15 | 1060 | |
5260325f | 1061 | /* This is the child processing a new connection. */ |
1062 | ||
aa3378df | 1063 | /* |
1064 | * Disable the key regeneration alarm. We will not regenerate the | |
1065 | * key since we are no longer in a position to give it to anyone. We | |
1066 | * will not restart on SIGHUP since it no longer makes sense. | |
1067 | */ | |
5260325f | 1068 | alarm(0); |
1069 | signal(SIGALRM, SIG_DFL); | |
1070 | signal(SIGHUP, SIG_DFL); | |
1071 | signal(SIGTERM, SIG_DFL); | |
1072 | signal(SIGQUIT, SIG_DFL); | |
1073 | signal(SIGCHLD, SIG_DFL); | |
9aaf9be4 | 1074 | signal(SIGINT, SIG_DFL); |
5260325f | 1075 | |
aa3378df | 1076 | /* |
1077 | * Set socket options for the connection. We want the socket to | |
1078 | * close as fast as possible without waiting for anything. If the | |
1079 | * connection is not a socket, these will do nothing. | |
1080 | */ | |
1081 | /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 1082 | linger.l_onoff = 1; |
1083 | linger.l_linger = 5; | |
1084 | setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
1085 | ||
aa3378df | 1086 | /* |
1087 | * Register our connection. This turns encryption off because we do | |
1088 | * not have a key. | |
1089 | */ | |
5260325f | 1090 | packet_set_connection(sock_in, sock_out); |
1091 | ||
1092 | remote_port = get_remote_port(); | |
1093 | remote_ip = get_remote_ipaddr(); | |
1094 | ||
1095 | /* Check whether logins are denied from this host. */ | |
1096 | #ifdef LIBWRAP | |
48e671d5 | 1097 | /* XXX LIBWRAP noes not know about IPv6 */ |
5260325f | 1098 | { |
1099 | struct request_info req; | |
8efc0c15 | 1100 | |
5260325f | 1101 | request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL); |
1102 | fromhost(&req); | |
8efc0c15 | 1103 | |
5260325f | 1104 | if (!hosts_access(&req)) { |
1105 | close(sock_in); | |
1106 | close(sock_out); | |
1107 | refuse(&req); | |
1108 | } | |
48e671d5 | 1109 | /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */ |
8efc0c15 | 1110 | } |
48e671d5 | 1111 | #endif /* LIBWRAP */ |
5260325f | 1112 | /* Log the connection. */ |
1113 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
8efc0c15 | 1114 | |
aa3378df | 1115 | /* |
1116 | * We don\'t want to listen forever unless the other side | |
1117 | * successfully authenticates itself. So we set up an alarm which is | |
1118 | * cleared after successful authentication. A limit of zero | |
1119 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1120 | * mode; it is just annoying to have the server exit just when you | |
1121 | * are about to discover the bug. | |
1122 | */ | |
5260325f | 1123 | signal(SIGALRM, grace_alarm_handler); |
1124 | if (!debug_flag) | |
1125 | alarm(options.login_grace_time); | |
1126 | ||
7368a6c8 | 1127 | sshd_exchange_identification(sock_in, sock_out); |
aa3378df | 1128 | /* |
1129 | * Check that the connection comes from a privileged port. Rhosts- | |
1130 | * and Rhosts-RSA-Authentication only make sense from priviledged | |
1131 | * programs. Of course, if the intruder has root access on his local | |
1132 | * machine, he can connect from any port. So do not use these | |
1133 | * authentication methods from machines that you do not trust. | |
1134 | */ | |
5260325f | 1135 | if (remote_port >= IPPORT_RESERVED || |
1136 | remote_port < IPPORT_RESERVED / 2) { | |
fa08c86b | 1137 | debug("Rhosts Authentication methods disabled, " |
1138 | "originating port not trusted."); | |
5260325f | 1139 | options.rhosts_authentication = 0; |
1140 | options.rhosts_rsa_authentication = 0; | |
1141 | } | |
48e671d5 | 1142 | #ifdef KRB4 |
1143 | if (!packet_connection_is_ipv4() && | |
1144 | options.kerberos_authentication) { | |
1145 | debug("Kerberos Authentication disabled, only available for IPv4."); | |
1146 | options.kerberos_authentication = 0; | |
1147 | } | |
1148 | #endif /* KRB4 */ | |
1149 | ||
5260325f | 1150 | packet_set_nonblocking(); |
1151 | ||
7b2ea3a1 | 1152 | /* perform the key exchange */ |
7b2ea3a1 | 1153 | /* authenticate user and start session */ |
e78a59f5 | 1154 | if (compat20) { |
1155 | do_ssh2_kex(); | |
1156 | do_authentication2(); | |
1157 | } else { | |
1158 | do_ssh1_kex(); | |
1159 | do_authentication(); | |
1160 | } | |
8efc0c15 | 1161 | |
1162 | #ifdef KRB4 | |
5260325f | 1163 | /* Cleanup user's ticket cache file. */ |
1164 | if (options.kerberos_ticket_cleanup) | |
1165 | (void) dest_tkt(); | |
8efc0c15 | 1166 | #endif /* KRB4 */ |
1167 | ||
5260325f | 1168 | /* The connection has been terminated. */ |
1169 | verbose("Closing connection to %.100s", remote_ip); | |
8efc0c15 | 1170 | |
d94aa2ae | 1171 | #ifdef USE_PAM |
a5c9cd31 | 1172 | finish_pam(); |
d94aa2ae | 1173 | #endif /* USE_PAM */ |
8efc0c15 | 1174 | |
5260325f | 1175 | packet_close(); |
1176 | exit(0); | |
1177 | } | |
8efc0c15 | 1178 | |
5260325f | 1179 | /* |
7b2ea3a1 | 1180 | * SSH1 key exchange |
5260325f | 1181 | */ |
e7c0f9d5 | 1182 | void |
7368a6c8 | 1183 | do_ssh1_kex() |
8efc0c15 | 1184 | { |
5260325f | 1185 | int i, len; |
7b2ea3a1 | 1186 | int plen, slen; |
5260325f | 1187 | BIGNUM *session_key_int; |
1188 | unsigned char session_key[SSH_SESSION_KEY_LENGTH]; | |
7b2ea3a1 | 1189 | unsigned char cookie[8]; |
5260325f | 1190 | unsigned int cipher_type, auth_mask, protocol_flags; |
5260325f | 1191 | u_int32_t rand = 0; |
1192 | ||
aa3378df | 1193 | /* |
1194 | * Generate check bytes that the client must send back in the user | |
1195 | * packet in order for it to be accepted; this is used to defy ip | |
1196 | * spoofing attacks. Note that this only works against somebody | |
1197 | * doing IP spoofing from a remote machine; any machine on the local | |
1198 | * network can still see outgoing packets and catch the random | |
1199 | * cookie. This only affects rhosts authentication, and this is one | |
1200 | * of the reasons why it is inherently insecure. | |
1201 | */ | |
5260325f | 1202 | for (i = 0; i < 8; i++) { |
1203 | if (i % 4 == 0) | |
1204 | rand = arc4random(); | |
7b2ea3a1 | 1205 | cookie[i] = rand & 0xff; |
5260325f | 1206 | rand >>= 8; |
1207 | } | |
1208 | ||
aa3378df | 1209 | /* |
1210 | * Send our public key. We include in the packet 64 bits of random | |
1211 | * data that must be matched in the reply in order to prevent IP | |
1212 | * spoofing. | |
1213 | */ | |
5260325f | 1214 | packet_start(SSH_SMSG_PUBLIC_KEY); |
1215 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1216 | packet_put_char(cookie[i]); |
5260325f | 1217 | |
1218 | /* Store our public server RSA key. */ | |
fa08c86b | 1219 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); |
1220 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1221 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
5260325f | 1222 | |
1223 | /* Store our public host RSA key. */ | |
fa08c86b | 1224 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); |
1225 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1226 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
5260325f | 1227 | |
1228 | /* Put protocol flags. */ | |
1229 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1230 | ||
1231 | /* Declare which ciphers we support. */ | |
94ec8c6b | 1232 | packet_put_int(cipher_mask_ssh1(0)); |
5260325f | 1233 | |
1234 | /* Declare supported authentication types. */ | |
1235 | auth_mask = 0; | |
1236 | if (options.rhosts_authentication) | |
1237 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
1238 | if (options.rhosts_rsa_authentication) | |
1239 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1240 | if (options.rsa_authentication) | |
1241 | auth_mask |= 1 << SSH_AUTH_RSA; | |
8efc0c15 | 1242 | #ifdef KRB4 |
5260325f | 1243 | if (options.kerberos_authentication) |
1244 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
8efc0c15 | 1245 | #endif |
1246 | #ifdef AFS | |
5260325f | 1247 | if (options.kerberos_tgt_passing) |
1248 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
1249 | if (options.afs_token_passing) | |
1250 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
8efc0c15 | 1251 | #endif |
5260325f | 1252 | #ifdef SKEY |
1253 | if (options.skey_authentication == 1) | |
1254 | auth_mask |= 1 << SSH_AUTH_TIS; | |
1255 | #endif | |
1256 | if (options.password_authentication) | |
1257 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1258 | packet_put_int(auth_mask); | |
1259 | ||
1260 | /* Send the packet and wait for it to be sent. */ | |
1261 | packet_send(); | |
1262 | packet_write_wait(); | |
1263 | ||
fa08c86b | 1264 | debug("Sent %d bit server key and %d bit host key.", |
1265 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1266 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
5260325f | 1267 | |
1268 | /* Read clients reply (cipher type and session key). */ | |
1269 | packet_read_expect(&plen, SSH_CMSG_SESSION_KEY); | |
1270 | ||
2d86a6cc | 1271 | /* Get cipher type and check whether we accept this. */ |
5260325f | 1272 | cipher_type = packet_get_char(); |
1273 | ||
94ec8c6b | 1274 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) |
2d86a6cc | 1275 | packet_disconnect("Warning: client selects unsupported cipher."); |
1276 | ||
5260325f | 1277 | /* Get check bytes from the packet. These must match those we |
1278 | sent earlier with the public key packet. */ | |
1279 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1280 | if (cookie[i] != packet_get_char()) |
5260325f | 1281 | packet_disconnect("IP Spoofing check bytes do not match."); |
1282 | ||
1283 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1284 | ||
1285 | /* Get the encrypted integer. */ | |
1286 | session_key_int = BN_new(); | |
1287 | packet_get_bignum(session_key_int, &slen); | |
1288 | ||
5260325f | 1289 | protocol_flags = packet_get_int(); |
1290 | packet_set_protocol_flags(protocol_flags); | |
1291 | ||
1292 | packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY); | |
1293 | ||
aa3378df | 1294 | /* |
1295 | * Decrypt it using our private server key and private host key (key | |
1296 | * with larger modulus first). | |
1297 | */ | |
fa08c86b | 1298 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { |
5260325f | 1299 | /* Private key has bigger modulus. */ |
fa08c86b | 1300 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < |
1301 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1302 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1303 | get_remote_ipaddr(), | |
1304 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1305 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1306 | SSH_KEY_BITS_RESERVED); | |
5260325f | 1307 | } |
1308 | rsa_private_decrypt(session_key_int, session_key_int, | |
fa08c86b | 1309 | sensitive_data.server_key->rsa); |
5260325f | 1310 | rsa_private_decrypt(session_key_int, session_key_int, |
fa08c86b | 1311 | sensitive_data.ssh1_host_key->rsa); |
5260325f | 1312 | } else { |
1313 | /* Host key has bigger modulus (or they are equal). */ | |
fa08c86b | 1314 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < |
1315 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1316 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1317 | get_remote_ipaddr(), | |
1318 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1319 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1320 | SSH_KEY_BITS_RESERVED); | |
5260325f | 1321 | } |
1322 | rsa_private_decrypt(session_key_int, session_key_int, | |
fa08c86b | 1323 | sensitive_data.ssh1_host_key->rsa); |
5260325f | 1324 | rsa_private_decrypt(session_key_int, session_key_int, |
fa08c86b | 1325 | sensitive_data.server_key->rsa); |
5260325f | 1326 | } |
1327 | ||
7b2ea3a1 | 1328 | compute_session_id(session_id, cookie, |
fa08c86b | 1329 | sensitive_data.ssh1_host_key->rsa->n, |
1330 | sensitive_data.server_key->rsa->n); | |
5260325f | 1331 | |
7b2ea3a1 | 1332 | /* Destroy the private and public keys. They will no longer be needed. */ |
a306f2dd | 1333 | destroy_sensitive_data(); |
7b2ea3a1 | 1334 | |
aa3378df | 1335 | /* |
1336 | * Extract session key from the decrypted integer. The key is in the | |
1337 | * least significant 256 bits of the integer; the first byte of the | |
1338 | * key is in the highest bits. | |
1339 | */ | |
5260325f | 1340 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); |
1341 | len = BN_num_bytes(session_key_int); | |
1342 | if (len < 0 || len > sizeof(session_key)) | |
1343 | fatal("do_connection: bad len from %s: session_key_int %d > sizeof(session_key) %d", | |
fa08c86b | 1344 | get_remote_ipaddr(), |
1345 | len, sizeof(session_key)); | |
5260325f | 1346 | memset(session_key, 0, sizeof(session_key)); |
1347 | BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len); | |
1348 | ||
7b2ea3a1 | 1349 | /* Destroy the decrypted integer. It is no longer needed. */ |
1350 | BN_clear_free(session_key_int); | |
1351 | ||
5260325f | 1352 | /* Xor the first 16 bytes of the session key with the session id. */ |
1353 | for (i = 0; i < 16; i++) | |
1354 | session_key[i] ^= session_id[i]; | |
1355 | ||
5260325f | 1356 | /* Set the session key. From this on all communications will be encrypted. */ |
1357 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1358 | ||
1359 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1360 | memset(session_key, 0, sizeof(session_key)); | |
1361 | ||
1362 | debug("Received session key; encryption turned on."); | |
1363 | ||
1364 | /* Send an acknowledgement packet. Note that this packet is sent encrypted. */ | |
1365 | packet_start(SSH_SMSG_SUCCESS); | |
1366 | packet_send(); | |
1367 | packet_write_wait(); | |
5260325f | 1368 | } |
e78a59f5 | 1369 | |
1370 | /* | |
1371 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1372 | */ | |
1373 | void | |
1374 | do_ssh2_kex() | |
1375 | { | |
1376 | Buffer *server_kexinit; | |
1377 | Buffer *client_kexinit; | |
94ec8c6b | 1378 | int payload_len; |
e78a59f5 | 1379 | int i; |
e78a59f5 | 1380 | Kex *kex; |
e78a59f5 | 1381 | char *cprop[PROPOSAL_MAX]; |
e78a59f5 | 1382 | |
1383 | /* KEXINIT */ | |
1384 | ||
a8be9f80 | 1385 | if (options.ciphers != NULL) { |
6ae2364d | 1386 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
a8be9f80 | 1387 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
1388 | } | |
fa08c86b | 1389 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
1390 | ||
71276795 | 1391 | server_kexinit = kex_init(myproposal); |
e78a59f5 | 1392 | client_kexinit = xmalloc(sizeof(*client_kexinit)); |
1393 | buffer_init(client_kexinit); | |
e78a59f5 | 1394 | |
71276795 | 1395 | /* algorithm negotiation */ |
1396 | kex_exchange_kexinit(server_kexinit, client_kexinit, cprop); | |
1397 | kex = kex_choose_conf(cprop, myproposal, 1); | |
1398 | for (i = 0; i < PROPOSAL_MAX; i++) | |
1399 | xfree(cprop[i]); | |
e78a59f5 | 1400 | |
94ec8c6b | 1401 | switch (kex->kex_type) { |
1402 | case DH_GRP1_SHA1: | |
1403 | ssh_dh1_server(kex, client_kexinit, server_kexinit); | |
1404 | break; | |
1405 | case DH_GEX_SHA1: | |
1406 | ssh_dhgex_server(kex, client_kexinit, server_kexinit); | |
1407 | break; | |
1408 | default: | |
1409 | fatal("Unsupported key exchange %d", kex->kex_type); | |
1410 | } | |
1411 | ||
1412 | debug("send SSH2_MSG_NEWKEYS."); | |
1413 | packet_start(SSH2_MSG_NEWKEYS); | |
1414 | packet_send(); | |
1415 | packet_write_wait(); | |
1416 | debug("done: send SSH2_MSG_NEWKEYS."); | |
1417 | ||
1418 | debug("Wait SSH2_MSG_NEWKEYS."); | |
1419 | packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS); | |
1420 | debug("GOT SSH2_MSG_NEWKEYS."); | |
1421 | ||
1422 | #ifdef DEBUG_KEXDH | |
1423 | /* send 1st encrypted/maced/compressed message */ | |
1424 | packet_start(SSH2_MSG_IGNORE); | |
1425 | packet_put_cstring("markus"); | |
1426 | packet_send(); | |
1427 | packet_write_wait(); | |
1428 | #endif | |
1429 | ||
1430 | debug("done: KEX2."); | |
1431 | } | |
1432 | ||
1433 | /* | |
1434 | * SSH2 key exchange | |
1435 | */ | |
1436 | ||
1437 | /* diffie-hellman-group1-sha1 */ | |
1438 | ||
1439 | void | |
1440 | ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit) | |
1441 | { | |
1442 | #ifdef DEBUG_KEXDH | |
1443 | int i; | |
1444 | #endif | |
1445 | int payload_len, dlen; | |
1446 | int slen; | |
1447 | unsigned char *signature = NULL; | |
1448 | unsigned char *server_host_key_blob = NULL; | |
1449 | unsigned int sbloblen; | |
1450 | unsigned int klen, kout; | |
1451 | unsigned char *kbuf; | |
1452 | unsigned char *hash; | |
1453 | BIGNUM *shared_secret = 0; | |
1454 | DH *dh; | |
1455 | BIGNUM *dh_client_pub = 0; | |
fa08c86b | 1456 | Key *hostkey; |
1457 | ||
1458 | hostkey = get_hostkey_by_type(kex->hostkey_type); | |
1459 | if (hostkey == NULL) | |
1460 | fatal("Unsupported hostkey type %d", kex->hostkey_type); | |
e78a59f5 | 1461 | |
94ec8c6b | 1462 | /* KEXDH */ |
e78a59f5 | 1463 | debug("Wait SSH2_MSG_KEXDH_INIT."); |
1464 | packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT); | |
1465 | ||
1466 | /* key, cert */ | |
1467 | dh_client_pub = BN_new(); | |
1468 | if (dh_client_pub == NULL) | |
1469 | fatal("dh_client_pub == NULL"); | |
1470 | packet_get_bignum2(dh_client_pub, &dlen); | |
1471 | ||
1472 | #ifdef DEBUG_KEXDH | |
1473 | fprintf(stderr, "\ndh_client_pub= "); | |
188adeb2 | 1474 | BN_print_fp(stderr, dh_client_pub); |
e78a59f5 | 1475 | fprintf(stderr, "\n"); |
1476 | debug("bits %d", BN_num_bits(dh_client_pub)); | |
1477 | #endif | |
1478 | ||
1479 | /* generate DH key */ | |
a8be9f80 | 1480 | dh = dh_new_group1(); /* XXX depends on 'kex' */ |
e78a59f5 | 1481 | |
1482 | #ifdef DEBUG_KEXDH | |
1483 | fprintf(stderr, "\np= "); | |
188adeb2 | 1484 | BN_print_fp(stderr, dh->p); |
e78a59f5 | 1485 | fprintf(stderr, "\ng= "); |
188adeb2 | 1486 | bn_print(dh->g); |
e78a59f5 | 1487 | fprintf(stderr, "\npub= "); |
188adeb2 | 1488 | BN_print_fp(stderr, dh->pub_key); |
e78a59f5 | 1489 | fprintf(stderr, "\n"); |
188adeb2 | 1490 | DHparams_print_fp(stderr, dh); |
e78a59f5 | 1491 | #endif |
a8be9f80 | 1492 | if (!dh_pub_is_valid(dh, dh_client_pub)) |
1493 | packet_disconnect("bad client public DH value"); | |
e78a59f5 | 1494 | |
1495 | klen = DH_size(dh); | |
1496 | kbuf = xmalloc(klen); | |
1497 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | |
1498 | ||
1499 | #ifdef DEBUG_KEXDH | |
1500 | debug("shared secret: len %d/%d", klen, kout); | |
1501 | fprintf(stderr, "shared secret == "); | |
1502 | for (i = 0; i< kout; i++) | |
1503 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
1504 | fprintf(stderr, "\n"); | |
1505 | #endif | |
1506 | shared_secret = BN_new(); | |
1507 | ||
1508 | BN_bin2bn(kbuf, kout, shared_secret); | |
1509 | memset(kbuf, 0, klen); | |
1510 | xfree(kbuf); | |
1511 | ||
a306f2dd | 1512 | /* XXX precompute? */ |
fa08c86b | 1513 | key_to_blob(hostkey, &server_host_key_blob, &sbloblen); |
e78a59f5 | 1514 | |
1515 | /* calc H */ /* XXX depends on 'kex' */ | |
1516 | hash = kex_hash( | |
1517 | client_version_string, | |
1518 | server_version_string, | |
1519 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
1520 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
1521 | (char *)server_host_key_blob, sbloblen, | |
1522 | dh_client_pub, | |
1523 | dh->pub_key, | |
1524 | shared_secret | |
1525 | ); | |
1526 | buffer_free(client_kexinit); | |
1527 | buffer_free(server_kexinit); | |
1528 | xfree(client_kexinit); | |
1529 | xfree(server_kexinit); | |
1530 | #ifdef DEBUG_KEXDH | |
6ae2364d | 1531 | fprintf(stderr, "hash == "); |
1532 | for (i = 0; i< 20; i++) | |
1533 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
1534 | fprintf(stderr, "\n"); | |
e78a59f5 | 1535 | #endif |
a306f2dd | 1536 | /* save session id := H */ |
1537 | /* XXX hashlen depends on KEX */ | |
1538 | session_id2_len = 20; | |
1539 | session_id2 = xmalloc(session_id2_len); | |
1540 | memcpy(session_id2, hash, session_id2_len); | |
1541 | ||
e78a59f5 | 1542 | /* sign H */ |
a306f2dd | 1543 | /* XXX hashlen depends on KEX */ |
fa08c86b | 1544 | key_sign(hostkey, &signature, &slen, hash, 20); |
a306f2dd | 1545 | |
1546 | destroy_sensitive_data(); | |
e78a59f5 | 1547 | |
1548 | /* send server hostkey, DH pubkey 'f' and singed H */ | |
1549 | packet_start(SSH2_MSG_KEXDH_REPLY); | |
1550 | packet_put_string((char *)server_host_key_blob, sbloblen); | |
1d1ffb87 | 1551 | packet_put_bignum2(dh->pub_key); /* f */ |
e78a59f5 | 1552 | packet_put_string((char *)signature, slen); |
1553 | packet_send(); | |
d6f24e45 | 1554 | xfree(signature); |
a306f2dd | 1555 | xfree(server_host_key_blob); |
e78a59f5 | 1556 | packet_write_wait(); |
1557 | ||
1558 | kex_derive_keys(kex, hash, shared_secret); | |
1559 | packet_set_kex(kex); | |
1560 | ||
1561 | /* have keys, free DH */ | |
1562 | DH_free(dh); | |
94ec8c6b | 1563 | } |
e78a59f5 | 1564 | |
94ec8c6b | 1565 | /* diffie-hellman-group-exchange-sha1 */ |
1566 | ||
1567 | void | |
1568 | ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit) | |
1569 | { | |
1570 | #ifdef DEBUG_KEXDH | |
1571 | int i; | |
1572 | #endif | |
1573 | int payload_len, dlen; | |
1574 | int slen, nbits; | |
1575 | unsigned char *signature = NULL; | |
1576 | unsigned char *server_host_key_blob = NULL; | |
1577 | unsigned int sbloblen; | |
1578 | unsigned int klen, kout; | |
1579 | unsigned char *kbuf; | |
1580 | unsigned char *hash; | |
1581 | BIGNUM *shared_secret = 0; | |
1582 | DH *dh; | |
1583 | BIGNUM *dh_client_pub = 0; | |
fa08c86b | 1584 | Key *hostkey; |
1585 | ||
1586 | hostkey = get_hostkey_by_type(kex->hostkey_type); | |
1587 | if (hostkey == NULL) | |
1588 | fatal("Unsupported hostkey type %d", kex->hostkey_type); | |
94ec8c6b | 1589 | |
1590 | /* KEXDHGEX */ | |
1591 | debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST."); | |
1592 | packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_REQUEST); | |
1593 | nbits = packet_get_int(); | |
1594 | dh = choose_dh(nbits); | |
1595 | ||
1596 | debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP."); | |
1597 | packet_start(SSH2_MSG_KEX_DH_GEX_GROUP); | |
1598 | packet_put_bignum2(dh->p); | |
1599 | packet_put_bignum2(dh->g); | |
e78a59f5 | 1600 | packet_send(); |
1601 | packet_write_wait(); | |
e78a59f5 | 1602 | |
94ec8c6b | 1603 | debug("Wait SSH2_MSG_KEX_DH_GEX_INIT."); |
1604 | packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_INIT); | |
1605 | ||
1606 | /* key, cert */ | |
1607 | dh_client_pub = BN_new(); | |
1608 | if (dh_client_pub == NULL) | |
1609 | fatal("dh_client_pub == NULL"); | |
1610 | packet_get_bignum2(dh_client_pub, &dlen); | |
e78a59f5 | 1611 | |
a8be9f80 | 1612 | #ifdef DEBUG_KEXDH |
94ec8c6b | 1613 | fprintf(stderr, "\ndh_client_pub= "); |
1614 | BN_print_fp(stderr, dh_client_pub); | |
1615 | fprintf(stderr, "\n"); | |
1616 | debug("bits %d", BN_num_bits(dh_client_pub)); | |
1617 | #endif | |
1618 | ||
1619 | #ifdef DEBUG_KEXDH | |
1620 | fprintf(stderr, "\np= "); | |
1621 | BN_print_fp(stderr, dh->p); | |
1622 | fprintf(stderr, "\ng= "); | |
1623 | bn_print(dh->g); | |
1624 | fprintf(stderr, "\npub= "); | |
1625 | BN_print_fp(stderr, dh->pub_key); | |
1626 | fprintf(stderr, "\n"); | |
1627 | DHparams_print_fp(stderr, dh); | |
1628 | #endif | |
1629 | if (!dh_pub_is_valid(dh, dh_client_pub)) | |
1630 | packet_disconnect("bad client public DH value"); | |
1631 | ||
1632 | klen = DH_size(dh); | |
1633 | kbuf = xmalloc(klen); | |
1634 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | |
1635 | ||
1636 | #ifdef DEBUG_KEXDH | |
1637 | debug("shared secret: len %d/%d", klen, kout); | |
1638 | fprintf(stderr, "shared secret == "); | |
1639 | for (i = 0; i< kout; i++) | |
1640 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
1641 | fprintf(stderr, "\n"); | |
1642 | #endif | |
1643 | shared_secret = BN_new(); | |
1644 | ||
1645 | BN_bin2bn(kbuf, kout, shared_secret); | |
1646 | memset(kbuf, 0, klen); | |
1647 | xfree(kbuf); | |
1648 | ||
1649 | /* XXX precompute? */ | |
fa08c86b | 1650 | key_to_blob(hostkey, &server_host_key_blob, &sbloblen); |
94ec8c6b | 1651 | |
1652 | /* calc H */ /* XXX depends on 'kex' */ | |
1653 | hash = kex_hash_gex( | |
1654 | client_version_string, | |
1655 | server_version_string, | |
1656 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
1657 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
1658 | (char *)server_host_key_blob, sbloblen, | |
1659 | nbits, dh->p, dh->g, | |
1660 | dh_client_pub, | |
1661 | dh->pub_key, | |
1662 | shared_secret | |
1663 | ); | |
1664 | buffer_free(client_kexinit); | |
1665 | buffer_free(server_kexinit); | |
1666 | xfree(client_kexinit); | |
1667 | xfree(server_kexinit); | |
1668 | #ifdef DEBUG_KEXDH | |
1669 | fprintf(stderr, "hash == "); | |
1670 | for (i = 0; i< 20; i++) | |
1671 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
1672 | fprintf(stderr, "\n"); | |
1673 | #endif | |
1674 | /* save session id := H */ | |
1675 | /* XXX hashlen depends on KEX */ | |
1676 | session_id2_len = 20; | |
1677 | session_id2 = xmalloc(session_id2_len); | |
1678 | memcpy(session_id2, hash, session_id2_len); | |
1679 | ||
1680 | /* sign H */ | |
1681 | /* XXX hashlen depends on KEX */ | |
fa08c86b | 1682 | key_sign(hostkey, &signature, &slen, hash, 20); |
94ec8c6b | 1683 | |
1684 | destroy_sensitive_data(); | |
1685 | ||
1686 | /* send server hostkey, DH pubkey 'f' and singed H */ | |
1687 | packet_start(SSH2_MSG_KEX_DH_GEX_REPLY); | |
1688 | packet_put_string((char *)server_host_key_blob, sbloblen); | |
1689 | packet_put_bignum2(dh->pub_key); /* f */ | |
1690 | packet_put_string((char *)signature, slen); | |
e78a59f5 | 1691 | packet_send(); |
94ec8c6b | 1692 | xfree(signature); |
1693 | xfree(server_host_key_blob); | |
e78a59f5 | 1694 | packet_write_wait(); |
94ec8c6b | 1695 | |
1696 | kex_derive_keys(kex, hash, shared_secret); | |
1697 | packet_set_kex(kex); | |
1698 | ||
1699 | /* have keys, free DH */ | |
1700 | DH_free(dh); | |
e78a59f5 | 1701 | } |