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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" | |
b5c334cc | 43 | RCSID("$OpenBSD: sshd.c,v 1.150 2001/01/13 18:32:51 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 | ||
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 | /* Saved arguments to main(). */ |
121 | char **saved_argv; | |
4d33e531 | 122 | int saved_argc; |
8efc0c15 | 123 | |
aa3378df | 124 | /* |
48e671d5 | 125 | * The sockets that the server is listening; this is used in the SIGHUP |
126 | * signal handler. | |
aa3378df | 127 | */ |
48e671d5 | 128 | #define MAX_LISTEN_SOCKS 16 |
129 | int listen_socks[MAX_LISTEN_SOCKS]; | |
130 | int num_listen_socks = 0; | |
8efc0c15 | 131 | |
aa3378df | 132 | /* |
133 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
134 | * sshd will skip the version-number exchange | |
135 | */ | |
5260325f | 136 | char *client_version_string = NULL; |
7368a6c8 | 137 | char *server_version_string = NULL; |
8efc0c15 | 138 | |
aa3378df | 139 | /* |
140 | * Any really sensitive data in the application is contained in this | |
141 | * structure. The idea is that this structure could be locked into memory so | |
142 | * that the pages do not get written into swap. However, there are some | |
143 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
144 | * have access to the internals of them, and locking just the structure is | |
145 | * not very useful. Currently, memory locking is not implemented. | |
146 | */ | |
5260325f | 147 | struct { |
fa08c86b | 148 | Key *server_key; /* empheral server key */ |
149 | Key *ssh1_host_key; /* ssh1 host key */ | |
150 | Key **host_keys; /* all private host keys */ | |
151 | int have_ssh1_key; | |
152 | int have_ssh2_key; | |
8efc0c15 | 153 | } sensitive_data; |
154 | ||
aa3378df | 155 | /* |
156 | * Flag indicating whether the current session key has been used. This flag | |
157 | * is set whenever the key is used, and cleared when the key is regenerated. | |
158 | */ | |
8efc0c15 | 159 | int key_used = 0; |
160 | ||
161 | /* This is set to true when SIGHUP is received. */ | |
162 | int received_sighup = 0; | |
163 | ||
7368a6c8 | 164 | /* session identifier, used by RSA-auth */ |
1e3b8b07 | 165 | u_char session_id[16]; |
e7c0f9d5 | 166 | |
a306f2dd | 167 | /* same for ssh2 */ |
1e3b8b07 | 168 | u_char *session_id2 = NULL; |
a306f2dd | 169 | int session_id2_len = 0; |
170 | ||
c345cf9d | 171 | /* record remote hostname or ip */ |
1e3b8b07 | 172 | u_int utmp_len = MAXHOSTNAMELEN; |
c345cf9d | 173 | |
7368a6c8 | 174 | /* Prototypes for various functions defined later in this file. */ |
1e3b8b07 | 175 | void do_ssh1_kex(void); |
176 | void do_ssh2_kex(void); | |
c8d54615 | 177 | |
94ec8c6b | 178 | void ssh_dh1_server(Kex *, Buffer *_kexinit, Buffer *); |
179 | void ssh_dhgex_server(Kex *, Buffer *_kexinit, Buffer *); | |
180 | ||
48e671d5 | 181 | /* |
182 | * Close all listening sockets | |
183 | */ | |
184 | void | |
185 | close_listen_socks(void) | |
186 | { | |
187 | int i; | |
188 | for (i = 0; i < num_listen_socks; i++) | |
189 | close(listen_socks[i]); | |
190 | num_listen_socks = -1; | |
191 | } | |
192 | ||
5260325f | 193 | /* |
194 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
195 | * the effect is to reread the configuration file (and to regenerate | |
196 | * the server key). | |
197 | */ | |
6ae2364d | 198 | void |
5260325f | 199 | sighup_handler(int sig) |
8efc0c15 | 200 | { |
5260325f | 201 | received_sighup = 1; |
202 | signal(SIGHUP, sighup_handler); | |
8efc0c15 | 203 | } |
204 | ||
5260325f | 205 | /* |
206 | * Called from the main program after receiving SIGHUP. | |
207 | * Restarts the server. | |
208 | */ | |
6ae2364d | 209 | void |
5260325f | 210 | sighup_restart() |
8efc0c15 | 211 | { |
5260325f | 212 | log("Received SIGHUP; restarting."); |
48e671d5 | 213 | close_listen_socks(); |
5260325f | 214 | execv(saved_argv[0], saved_argv); |
1fe6a48f | 215 | log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno)); |
5260325f | 216 | exit(1); |
8efc0c15 | 217 | } |
218 | ||
5260325f | 219 | /* |
220 | * Generic signal handler for terminating signals in the master daemon. | |
221 | * These close the listen socket; not closing it seems to cause "Address | |
222 | * already in use" problems on some machines, which is inconvenient. | |
223 | */ | |
6ae2364d | 224 | void |
5260325f | 225 | sigterm_handler(int sig) |
8efc0c15 | 226 | { |
5260325f | 227 | log("Received signal %d; terminating.", sig); |
48e671d5 | 228 | close_listen_socks(); |
0fbe8c74 | 229 | unlink(options.pid_file); |
5260325f | 230 | exit(255); |
8efc0c15 | 231 | } |
232 | ||
5260325f | 233 | /* |
234 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
235 | * reap any zombies left by exited c. | |
236 | */ | |
6ae2364d | 237 | void |
5260325f | 238 | main_sigchld_handler(int sig) |
8efc0c15 | 239 | { |
5260325f | 240 | int save_errno = errno; |
241 | int status; | |
5ad13cd7 | 242 | |
5260325f | 243 | while (waitpid(-1, &status, WNOHANG) > 0) |
244 | ; | |
5ad13cd7 | 245 | |
5260325f | 246 | signal(SIGCHLD, main_sigchld_handler); |
247 | errno = save_errno; | |
8efc0c15 | 248 | } |
249 | ||
5260325f | 250 | /* |
251 | * Signal handler for the alarm after the login grace period has expired. | |
252 | */ | |
6ae2364d | 253 | void |
5260325f | 254 | grace_alarm_handler(int sig) |
8efc0c15 | 255 | { |
5260325f | 256 | /* Close the connection. */ |
257 | packet_close(); | |
8efc0c15 | 258 | |
5260325f | 259 | /* Log error and exit. */ |
260 | fatal("Timeout before authentication for %s.", get_remote_ipaddr()); | |
261 | } | |
8efc0c15 | 262 | |
5260325f | 263 | /* |
264 | * Signal handler for the key regeneration alarm. Note that this | |
265 | * alarm only occurs in the daemon waiting for connections, and it does not | |
266 | * do anything with the private key or random state before forking. | |
267 | * Thus there should be no concurrency control/asynchronous execution | |
268 | * problems. | |
f546c780 | 269 | * XXX calling log() is not safe from races. |
5260325f | 270 | */ |
6ae2364d | 271 | void |
fa08c86b | 272 | generate_empheral_server_key(void) |
273 | { | |
274 | log("Generating %s%d bit RSA key.", sensitive_data.server_key ? "new " : "", | |
275 | options.server_key_bits); | |
276 | if (sensitive_data.server_key != NULL) | |
277 | key_free(sensitive_data.server_key); | |
278 | sensitive_data.server_key = key_generate(KEY_RSA1, options.server_key_bits); | |
279 | arc4random_stir(); | |
280 | log("RSA key generation complete."); | |
281 | } | |
f546c780 | 282 | |
fa08c86b | 283 | void |
5260325f | 284 | key_regeneration_alarm(int sig) |
285 | { | |
286 | int save_errno = errno; | |
287 | ||
288 | /* Check if we should generate a new key. */ | |
289 | if (key_used) { | |
290 | /* This should really be done in the background. */ | |
fa08c86b | 291 | generate_empheral_server_key(); |
5260325f | 292 | key_used = 0; |
5260325f | 293 | } |
294 | /* Reschedule the alarm. */ | |
295 | signal(SIGALRM, key_regeneration_alarm); | |
296 | alarm(options.key_regeneration_time); | |
297 | errno = save_errno; | |
298 | } | |
8efc0c15 | 299 | |
7368a6c8 | 300 | void |
301 | sshd_exchange_identification(int sock_in, int sock_out) | |
302 | { | |
a8be9f80 | 303 | int i, mismatch; |
7368a6c8 | 304 | int remote_major, remote_minor; |
a8be9f80 | 305 | int major, minor; |
7368a6c8 | 306 | char *s; |
307 | char buf[256]; /* Must not be larger than remote_version. */ | |
308 | char remote_version[256]; /* Must be at least as big as buf. */ | |
309 | ||
a8be9f80 | 310 | if ((options.protocol & SSH_PROTO_1) && |
311 | (options.protocol & SSH_PROTO_2)) { | |
312 | major = PROTOCOL_MAJOR_1; | |
313 | minor = 99; | |
314 | } else if (options.protocol & SSH_PROTO_2) { | |
315 | major = PROTOCOL_MAJOR_2; | |
316 | minor = PROTOCOL_MINOR_2; | |
317 | } else { | |
318 | major = PROTOCOL_MAJOR_1; | |
319 | minor = PROTOCOL_MINOR_1; | |
320 | } | |
321 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
7368a6c8 | 322 | server_version_string = xstrdup(buf); |
323 | ||
324 | if (client_version_string == NULL) { | |
325 | /* Send our protocol version identification. */ | |
326 | if (atomicio(write, sock_out, server_version_string, strlen(server_version_string)) | |
327 | != strlen(server_version_string)) { | |
328 | log("Could not write ident string to %s.", get_remote_ipaddr()); | |
329 | fatal_cleanup(); | |
330 | } | |
331 | ||
332 | /* Read other side\'s version identification. */ | |
333 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
e5a0294f | 334 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { |
7368a6c8 | 335 | log("Did not receive ident string from %s.", get_remote_ipaddr()); |
336 | fatal_cleanup(); | |
337 | } | |
338 | if (buf[i] == '\r') { | |
339 | buf[i] = '\n'; | |
340 | buf[i + 1] = 0; | |
94ec8c6b | 341 | /* Kludge for F-Secure Macintosh < 1.0.2 */ |
342 | if (i == 12 && | |
343 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
344 | break; | |
7368a6c8 | 345 | continue; |
7368a6c8 | 346 | } |
347 | if (buf[i] == '\n') { | |
348 | /* buf[i] == '\n' */ | |
349 | buf[i + 1] = 0; | |
350 | break; | |
351 | } | |
352 | } | |
353 | buf[sizeof(buf) - 1] = 0; | |
354 | client_version_string = xstrdup(buf); | |
355 | } | |
356 | ||
357 | /* | |
358 | * Check that the versions match. In future this might accept | |
359 | * several versions and set appropriate flags to handle them. | |
360 | */ | |
361 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
362 | &remote_major, &remote_minor, remote_version) != 3) { | |
6ae2364d | 363 | s = "Protocol mismatch.\n"; |
7368a6c8 | 364 | (void) atomicio(write, sock_out, s, strlen(s)); |
365 | close(sock_in); | |
366 | close(sock_out); | |
367 | log("Bad protocol version identification '%.100s' from %s", | |
368 | client_version_string, get_remote_ipaddr()); | |
369 | fatal_cleanup(); | |
370 | } | |
371 | debug("Client protocol version %d.%d; client software version %.100s", | |
372 | remote_major, remote_minor, remote_version); | |
373 | ||
e78a59f5 | 374 | compat_datafellows(remote_version); |
375 | ||
a8be9f80 | 376 | mismatch = 0; |
7368a6c8 | 377 | switch(remote_major) { |
378 | case 1: | |
a306f2dd | 379 | if (remote_minor == 99) { |
380 | if (options.protocol & SSH_PROTO_2) | |
381 | enable_compat20(); | |
382 | else | |
383 | mismatch = 1; | |
384 | break; | |
385 | } | |
a8be9f80 | 386 | if (!(options.protocol & SSH_PROTO_1)) { |
387 | mismatch = 1; | |
388 | break; | |
389 | } | |
7368a6c8 | 390 | if (remote_minor < 3) { |
089fbbd2 | 391 | packet_disconnect("Your ssh version is too old and " |
7368a6c8 | 392 | "is no longer supported. Please install a newer version."); |
393 | } else if (remote_minor == 3) { | |
394 | /* note that this disables agent-forwarding */ | |
395 | enable_compat13(); | |
396 | } | |
a8be9f80 | 397 | break; |
e78a59f5 | 398 | case 2: |
a8be9f80 | 399 | if (options.protocol & SSH_PROTO_2) { |
e78a59f5 | 400 | enable_compat20(); |
401 | break; | |
402 | } | |
403 | /* FALLTHROUGH */ | |
6ae2364d | 404 | default: |
a8be9f80 | 405 | mismatch = 1; |
406 | break; | |
407 | } | |
408 | chop(server_version_string); | |
409 | chop(client_version_string); | |
410 | debug("Local version string %.200s", server_version_string); | |
411 | ||
412 | if (mismatch) { | |
7368a6c8 | 413 | s = "Protocol major versions differ.\n"; |
414 | (void) atomicio(write, sock_out, s, strlen(s)); | |
415 | close(sock_in); | |
416 | close(sock_out); | |
a8be9f80 | 417 | log("Protocol major versions differ for %s: %.200s vs. %.200s", |
418 | get_remote_ipaddr(), | |
419 | server_version_string, client_version_string); | |
7368a6c8 | 420 | fatal_cleanup(); |
7368a6c8 | 421 | } |
a306f2dd | 422 | if (compat20) |
423 | packet_set_ssh2_format(); | |
424 | } | |
425 | ||
426 | ||
fa08c86b | 427 | /* Destroy the host and server keys. They will no longer be needed. */ |
a306f2dd | 428 | void |
429 | destroy_sensitive_data(void) | |
430 | { | |
fa08c86b | 431 | int i; |
432 | ||
433 | if (sensitive_data.server_key) { | |
434 | key_free(sensitive_data.server_key); | |
435 | sensitive_data.server_key = NULL; | |
436 | } | |
437 | for(i = 0; i < options.num_host_key_files; i++) { | |
438 | if (sensitive_data.host_keys[i]) { | |
439 | key_free(sensitive_data.host_keys[i]); | |
440 | sensitive_data.host_keys[i] = NULL; | |
441 | } | |
442 | } | |
443 | sensitive_data.ssh1_host_key = NULL; | |
444 | } | |
445 | Key * | |
446 | load_private_key_autodetect(const char *filename) | |
447 | { | |
448 | struct stat st; | |
449 | int type; | |
450 | Key *public, *private; | |
451 | ||
452 | if (stat(filename, &st) < 0) { | |
453 | perror(filename); | |
454 | return NULL; | |
455 | } | |
456 | /* | |
457 | * try to load the public key. right now this only works for RSA1, | |
458 | * since SSH2 keys are fully encrypted | |
459 | */ | |
460 | type = KEY_RSA1; | |
461 | public = key_new(type); | |
462 | if (!load_public_key(filename, public, NULL)) { | |
463 | /* ok, so we will assume this is 'some' key */ | |
464 | type = KEY_UNSPEC; | |
465 | } | |
466 | key_free(public); | |
467 | ||
468 | /* Ok, try key with empty passphrase */ | |
469 | private = key_new(type); | |
470 | if (load_private_key(filename, "", private, NULL)) { | |
471 | debug("load_private_key_autodetect: type %d %s", | |
472 | private->type, key_type(private)); | |
473 | return private; | |
474 | } | |
475 | key_free(private); | |
476 | return NULL; | |
477 | } | |
478 | ||
479 | char * | |
480 | list_hostkey_types(void) | |
481 | { | |
482 | static char buf[1024]; | |
483 | int i; | |
484 | buf[0] = '\0'; | |
485 | for(i = 0; i < options.num_host_key_files; i++) { | |
486 | Key *key = sensitive_data.host_keys[i]; | |
487 | if (key == NULL) | |
488 | continue; | |
489 | switch(key->type) { | |
490 | case KEY_RSA: | |
491 | case KEY_DSA: | |
492 | strlcat(buf, key_ssh_name(key), sizeof buf); | |
493 | strlcat(buf, ",", sizeof buf); | |
494 | break; | |
495 | } | |
496 | } | |
497 | i = strlen(buf); | |
498 | if (i > 0 && buf[i-1] == ',') | |
499 | buf[i-1] = '\0'; | |
500 | debug("list_hostkey_types: %s", buf); | |
501 | return buf; | |
502 | } | |
503 | ||
504 | Key * | |
505 | get_hostkey_by_type(int type) | |
506 | { | |
507 | int i; | |
508 | for(i = 0; i < options.num_host_key_files; i++) { | |
509 | Key *key = sensitive_data.host_keys[i]; | |
510 | if (key != NULL && key->type == type) | |
511 | return key; | |
512 | } | |
513 | return NULL; | |
7368a6c8 | 514 | } |
515 | ||
c345cf9d | 516 | /* |
517 | * returns 1 if connection should be dropped, 0 otherwise. | |
518 | * dropping starts at connection #max_startups_begin with a probability | |
519 | * of (max_startups_rate/100). the probability increases linearly until | |
520 | * all connections are dropped for startups > max_startups | |
521 | */ | |
522 | int | |
523 | drop_connection(int startups) | |
524 | { | |
525 | double p, r; | |
526 | ||
527 | if (startups < options.max_startups_begin) | |
528 | return 0; | |
529 | if (startups >= options.max_startups) | |
530 | return 1; | |
531 | if (options.max_startups_rate == 100) | |
532 | return 1; | |
533 | ||
534 | p = 100 - options.max_startups_rate; | |
535 | p *= startups - options.max_startups_begin; | |
536 | p /= (double) (options.max_startups - options.max_startups_begin); | |
537 | p += options.max_startups_rate; | |
538 | p /= 100.0; | |
539 | r = arc4random() / (double) UINT_MAX; | |
540 | ||
541 | debug("drop_connection: p %g, r %g", p, r); | |
542 | return (r < p) ? 1 : 0; | |
543 | } | |
544 | ||
089fbbd2 | 545 | int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */ |
546 | int startup_pipe; /* in child */ | |
547 | ||
5260325f | 548 | /* |
549 | * Main program for the daemon. | |
550 | */ | |
8efc0c15 | 551 | int |
552 | main(int ac, char **av) | |
553 | { | |
5260325f | 554 | extern char *optarg; |
555 | extern int optind; | |
089fbbd2 | 556 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; |
9da5c3c9 | 557 | pid_t pid; |
48e671d5 | 558 | socklen_t fromlen; |
a306f2dd | 559 | int silent = 0; |
48e671d5 | 560 | fd_set *fdset; |
561 | struct sockaddr_storage from; | |
5260325f | 562 | const char *remote_ip; |
563 | int remote_port; | |
5260325f | 564 | FILE *f; |
565 | struct linger linger; | |
48e671d5 | 566 | struct addrinfo *ai; |
567 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
568 | int listen_sock, maxfd; | |
089fbbd2 | 569 | int startup_p[2]; |
570 | int startups = 0; | |
5260325f | 571 | |
260d427b | 572 | __progname = get_progname(av[0]); |
264dce47 | 573 | init_rng(); |
574 | ||
1fe6a48f | 575 | /* Save argv. */ |
4d33e531 | 576 | saved_argc = ac; |
5260325f | 577 | saved_argv = av; |
5260325f | 578 | |
579 | /* Initialize configuration options to their default values. */ | |
580 | initialize_server_options(&options); | |
581 | ||
582 | /* Parse command-line arguments. */ | |
b5c334cc | 583 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:dDiqQ46")) != -1) { |
5260325f | 584 | switch (opt) { |
48e671d5 | 585 | case '4': |
586 | IPv4or6 = AF_INET; | |
587 | break; | |
588 | case '6': | |
589 | IPv4or6 = AF_INET6; | |
590 | break; | |
5260325f | 591 | case 'f': |
592 | config_file_name = optarg; | |
593 | break; | |
594 | case 'd': | |
bcbf86ec | 595 | if (0 == debug_flag) { |
596 | debug_flag = 1; | |
597 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
598 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
599 | options.log_level++; | |
600 | } else { | |
601 | fprintf(stderr, "Too high debugging level.\n"); | |
602 | exit(1); | |
603 | } | |
5260325f | 604 | break; |
0b6fbf03 | 605 | case 'D': |
606 | no_daemon_flag = 1; | |
607 | break; | |
5260325f | 608 | case 'i': |
609 | inetd_flag = 1; | |
610 | break; | |
611 | case 'Q': | |
a306f2dd | 612 | silent = 1; |
5260325f | 613 | break; |
614 | case 'q': | |
615 | options.log_level = SYSLOG_LEVEL_QUIET; | |
616 | break; | |
617 | case 'b': | |
618 | options.server_key_bits = atoi(optarg); | |
619 | break; | |
620 | case 'p': | |
48e671d5 | 621 | options.ports_from_cmdline = 1; |
bcbf86ec | 622 | if (options.num_ports >= MAX_PORTS) { |
623 | fprintf(stderr, "too many ports.\n"); | |
624 | exit(1); | |
625 | } | |
48e671d5 | 626 | options.ports[options.num_ports++] = atoi(optarg); |
5260325f | 627 | break; |
628 | case 'g': | |
629 | options.login_grace_time = atoi(optarg); | |
630 | break; | |
631 | case 'k': | |
632 | options.key_regeneration_time = atoi(optarg); | |
633 | break; | |
634 | case 'h': | |
fa08c86b | 635 | if (options.num_host_key_files >= MAX_HOSTKEYS) { |
636 | fprintf(stderr, "too many host keys.\n"); | |
637 | exit(1); | |
638 | } | |
639 | options.host_key_files[options.num_host_key_files++] = optarg; | |
5260325f | 640 | break; |
641 | case 'V': | |
642 | client_version_string = optarg; | |
643 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
644 | inetd_flag = 1; | |
645 | break; | |
c345cf9d | 646 | case 'u': |
647 | utmp_len = atoi(optarg); | |
648 | break; | |
5260325f | 649 | case '?': |
650 | default: | |
651 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
1fe6a48f | 652 | fprintf(stderr, "Usage: %s [options]\n", __progname); |
5260325f | 653 | fprintf(stderr, "Options:\n"); |
aa3378df | 654 | fprintf(stderr, " -f file Configuration file (default %s)\n", SERVER_CONFIG_FILE); |
bcbf86ec | 655 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); |
5260325f | 656 | fprintf(stderr, " -i Started from inetd\n"); |
8abcdba4 | 657 | fprintf(stderr, " -D Do not fork into daemon mode\n"); |
5260325f | 658 | fprintf(stderr, " -q Quiet (no logging)\n"); |
659 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
660 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
9616313f | 661 | fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n"); |
5260325f | 662 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); |
663 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
48e671d5 | 664 | HOST_KEY_FILE); |
c345cf9d | 665 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); |
48e671d5 | 666 | fprintf(stderr, " -4 Use IPv4 only\n"); |
667 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
5260325f | 668 | exit(1); |
669 | } | |
670 | } | |
671 | ||
48e671d5 | 672 | /* |
673 | * Force logging to stderr until we have loaded the private host | |
674 | * key (unless started from inetd) | |
675 | */ | |
1fe6a48f | 676 | log_init(__progname, |
bbcf899f | 677 | options.log_level == -1 ? SYSLOG_LEVEL_NOTICE : options.log_level, |
48e671d5 | 678 | options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility, |
a306f2dd | 679 | !silent && !inetd_flag); |
48e671d5 | 680 | |
5260325f | 681 | /* Read server configuration options from the configuration file. */ |
682 | read_server_config(&options, config_file_name); | |
683 | ||
684 | /* Fill in default values for those options not explicitly set. */ | |
685 | fill_default_server_options(&options); | |
686 | ||
5260325f | 687 | /* Check that there are no remaining arguments. */ |
688 | if (optind < ac) { | |
689 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
690 | exit(1); | |
8efc0c15 | 691 | } |
5260325f | 692 | |
693 | debug("sshd version %.100s", SSH_VERSION); | |
694 | ||
fa08c86b | 695 | /* load private host keys */ |
696 | sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*)); | |
1e3b8b07 | 697 | for(i = 0; i < options.num_host_key_files; i++) |
698 | sensitive_data.host_keys[i] = NULL; | |
fa08c86b | 699 | sensitive_data.server_key = NULL; |
700 | sensitive_data.ssh1_host_key = NULL; | |
701 | sensitive_data.have_ssh1_key = 0; | |
702 | sensitive_data.have_ssh2_key = 0; | |
a306f2dd | 703 | |
fa08c86b | 704 | for(i = 0; i < options.num_host_key_files; i++) { |
705 | Key *key = load_private_key_autodetect(options.host_key_files[i]); | |
706 | if (key == NULL) { | |
a306f2dd | 707 | error("Could not load host key: %.200s: %.100s", |
fa08c86b | 708 | options.host_key_files[i], strerror(errno)); |
709 | continue; | |
a306f2dd | 710 | } |
fa08c86b | 711 | switch(key->type){ |
712 | case KEY_RSA1: | |
713 | sensitive_data.ssh1_host_key = key; | |
714 | sensitive_data.have_ssh1_key = 1; | |
715 | break; | |
716 | case KEY_RSA: | |
717 | case KEY_DSA: | |
718 | sensitive_data.have_ssh2_key = 1; | |
719 | break; | |
a306f2dd | 720 | } |
fa08c86b | 721 | sensitive_data.host_keys[i] = key; |
722 | } | |
723 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
724 | log("Disabling protocol version 1. Could not load host key"); | |
725 | options.protocol &= ~SSH_PROTO_1; | |
726 | } | |
727 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
728 | log("Disabling protocol version 2. Could not load host key"); | |
729 | options.protocol &= ~SSH_PROTO_2; | |
a306f2dd | 730 | } |
731 | if (! options.protocol & (SSH_PROTO_1|SSH_PROTO_2)) { | |
732 | if (silent == 0) | |
733 | fprintf(stderr, "sshd: no hostkeys available -- exiting.\n"); | |
734 | log("sshd: no hostkeys available -- exiting.\n"); | |
5260325f | 735 | exit(1); |
736 | } | |
5260325f | 737 | |
a306f2dd | 738 | /* Check certain values for sanity. */ |
739 | if (options.protocol & SSH_PROTO_1) { | |
740 | if (options.server_key_bits < 512 || | |
741 | options.server_key_bits > 32768) { | |
742 | fprintf(stderr, "Bad server key size.\n"); | |
743 | exit(1); | |
744 | } | |
745 | /* | |
746 | * Check that server and host key lengths differ sufficiently. This | |
747 | * is necessary to make double encryption work with rsaref. Oh, I | |
748 | * hate software patents. I dont know if this can go? Niels | |
749 | */ | |
750 | if (options.server_key_bits > | |
fa08c86b | 751 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED && |
a306f2dd | 752 | options.server_key_bits < |
fa08c86b | 753 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { |
a306f2dd | 754 | options.server_key_bits = |
fa08c86b | 755 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED; |
a306f2dd | 756 | debug("Forcing server key to %d bits to make it differ from host key.", |
757 | options.server_key_bits); | |
758 | } | |
759 | } | |
760 | ||
77bb0bca | 761 | #ifdef HAVE_SCO_PROTECTED_PW |
762 | (void) set_auth_parameters(ac, av); | |
763 | #endif | |
764 | ||
a306f2dd | 765 | /* Initialize the log (it is reinitialized below in case we forked). */ |
5260325f | 766 | if (debug_flag && !inetd_flag) |
767 | log_stderr = 1; | |
1fe6a48f | 768 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 769 | |
a306f2dd | 770 | /* |
771 | * If not in debugging mode, and not started from inetd, disconnect | |
772 | * from the controlling terminal, and fork. The original process | |
773 | * exits. | |
774 | */ | |
0b6fbf03 | 775 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { |
8efc0c15 | 776 | #ifdef TIOCNOTTY |
5260325f | 777 | int fd; |
8efc0c15 | 778 | #endif /* TIOCNOTTY */ |
5260325f | 779 | if (daemon(0, 0) < 0) |
780 | fatal("daemon() failed: %.200s", strerror(errno)); | |
781 | ||
782 | /* Disconnect from the controlling tty. */ | |
8efc0c15 | 783 | #ifdef TIOCNOTTY |
5260325f | 784 | fd = open("/dev/tty", O_RDWR | O_NOCTTY); |
785 | if (fd >= 0) { | |
786 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
787 | close(fd); | |
788 | } | |
8efc0c15 | 789 | #endif /* TIOCNOTTY */ |
8efc0c15 | 790 | } |
5260325f | 791 | /* Reinitialize the log (because of the fork above). */ |
1fe6a48f | 792 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 793 | |
5260325f | 794 | /* Initialize the random number generator. */ |
795 | arc4random_stir(); | |
796 | ||
797 | /* Chdir to the root directory so that the current disk can be | |
798 | unmounted if desired. */ | |
799 | chdir("/"); | |
800 | ||
5260325f | 801 | /* Start listening for a socket, unless started from inetd. */ |
802 | if (inetd_flag) { | |
803 | int s1, s2; | |
804 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ | |
805 | s2 = dup(s1); | |
806 | sock_in = dup(0); | |
807 | sock_out = dup(1); | |
4c8722d9 | 808 | startup_pipe = -1; |
a306f2dd | 809 | /* |
810 | * We intentionally do not close the descriptors 0, 1, and 2 | |
811 | * as our code for setting the descriptors won\'t work if | |
812 | * ttyfd happens to be one of those. | |
813 | */ | |
5260325f | 814 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); |
fa08c86b | 815 | if (options.protocol & SSH_PROTO_1) |
816 | generate_empheral_server_key(); | |
5260325f | 817 | } else { |
48e671d5 | 818 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
819 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
820 | continue; | |
821 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
822 | fatal("Too many listen sockets. " | |
823 | "Enlarge MAX_LISTEN_SOCKS"); | |
824 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
825 | ntop, sizeof(ntop), strport, sizeof(strport), | |
826 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
827 | error("getnameinfo failed"); | |
828 | continue; | |
829 | } | |
830 | /* Create socket for listening. */ | |
831 | listen_sock = socket(ai->ai_family, SOCK_STREAM, 0); | |
832 | if (listen_sock < 0) { | |
833 | /* kernel may not support ipv6 */ | |
834 | verbose("socket: %.100s", strerror(errno)); | |
835 | continue; | |
836 | } | |
837 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
838 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
839 | close(listen_sock); | |
840 | continue; | |
841 | } | |
842 | /* | |
843 | * Set socket options. We try to make the port | |
844 | * reusable and have it close as fast as possible | |
845 | * without waiting in unnecessary wait states on | |
846 | * close. | |
847 | */ | |
848 | setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, | |
849 | (void *) &on, sizeof(on)); | |
850 | linger.l_onoff = 1; | |
851 | linger.l_linger = 5; | |
852 | setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, | |
853 | (void *) &linger, sizeof(linger)); | |
854 | ||
855 | debug("Bind to port %s on %s.", strport, ntop); | |
856 | ||
857 | /* Bind the socket to the desired port. */ | |
16218745 | 858 | if ((bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) && |
859 | (!ai->ai_next)) { | |
48e671d5 | 860 | error("Bind to port %s on %s failed: %.200s.", |
861 | strport, ntop, strerror(errno)); | |
862 | close(listen_sock); | |
863 | continue; | |
864 | } | |
865 | listen_socks[num_listen_socks] = listen_sock; | |
866 | num_listen_socks++; | |
867 | ||
868 | /* Start listening on the port. */ | |
869 | log("Server listening on %s port %s.", ntop, strport); | |
870 | if (listen(listen_sock, 5) < 0) | |
871 | fatal("listen: %.100s", strerror(errno)); | |
872 | ||
5260325f | 873 | } |
48e671d5 | 874 | freeaddrinfo(options.listen_addrs); |
875 | ||
876 | if (!num_listen_socks) | |
877 | fatal("Cannot bind any address."); | |
878 | ||
5260325f | 879 | if (!debug_flag) { |
aa3378df | 880 | /* |
97fb6912 | 881 | * Record our pid in /var/run/sshd.pid to make it |
882 | * easier to kill the correct sshd. We don't want to | |
883 | * do this before the bind above because the bind will | |
aa3378df | 884 | * fail if there already is a daemon, and this will |
885 | * overwrite any old pid in the file. | |
886 | */ | |
3c62e7eb | 887 | f = fopen(options.pid_file, "wb"); |
5260325f | 888 | if (f) { |
1e3b8b07 | 889 | fprintf(f, "%u\n", (u_int) getpid()); |
5260325f | 890 | fclose(f); |
891 | } | |
8efc0c15 | 892 | } |
a306f2dd | 893 | if (options.protocol & SSH_PROTO_1) { |
fa08c86b | 894 | generate_empheral_server_key(); |
5260325f | 895 | |
a306f2dd | 896 | /* Schedule server key regeneration alarm. */ |
897 | signal(SIGALRM, key_regeneration_alarm); | |
898 | alarm(options.key_regeneration_time); | |
899 | } | |
5260325f | 900 | |
901 | /* Arrange to restart on SIGHUP. The handler needs listen_sock. */ | |
902 | signal(SIGHUP, sighup_handler); | |
089fbbd2 | 903 | |
5260325f | 904 | signal(SIGTERM, sigterm_handler); |
905 | signal(SIGQUIT, sigterm_handler); | |
906 | ||
907 | /* Arrange SIGCHLD to be caught. */ | |
908 | signal(SIGCHLD, main_sigchld_handler); | |
909 | ||
48e671d5 | 910 | /* setup fd set for listen */ |
089fbbd2 | 911 | fdset = NULL; |
48e671d5 | 912 | maxfd = 0; |
913 | for (i = 0; i < num_listen_socks; i++) | |
914 | if (listen_socks[i] > maxfd) | |
915 | maxfd = listen_socks[i]; | |
089fbbd2 | 916 | /* pipes connected to unauthenticated childs */ |
917 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
918 | for (i = 0; i < options.max_startups; i++) | |
919 | startup_pipes[i] = -1; | |
48e671d5 | 920 | |
aa3378df | 921 | /* |
922 | * Stay listening for connections until the system crashes or | |
923 | * the daemon is killed with a signal. | |
924 | */ | |
5260325f | 925 | for (;;) { |
926 | if (received_sighup) | |
927 | sighup_restart(); | |
089fbbd2 | 928 | if (fdset != NULL) |
929 | xfree(fdset); | |
b5c334cc | 930 | fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); |
089fbbd2 | 931 | fdset = (fd_set *)xmalloc(fdsetsz); |
48e671d5 | 932 | memset(fdset, 0, fdsetsz); |
089fbbd2 | 933 | |
48e671d5 | 934 | for (i = 0; i < num_listen_socks; i++) |
935 | FD_SET(listen_socks[i], fdset); | |
089fbbd2 | 936 | for (i = 0; i < options.max_startups; i++) |
937 | if (startup_pipes[i] != -1) | |
938 | FD_SET(startup_pipes[i], fdset); | |
939 | ||
940 | /* Wait in select until there is a connection. */ | |
b5c334cc | 941 | if (select(maxfd+1, fdset, NULL, NULL, NULL) < 0) { |
48e671d5 | 942 | if (errno != EINTR) |
943 | error("select: %.100s", strerror(errno)); | |
2d86a6cc | 944 | continue; |
48e671d5 | 945 | } |
089fbbd2 | 946 | for (i = 0; i < options.max_startups; i++) |
947 | if (startup_pipes[i] != -1 && | |
948 | FD_ISSET(startup_pipes[i], fdset)) { | |
949 | /* | |
950 | * the read end of the pipe is ready | |
951 | * if the child has closed the pipe | |
8abcdba4 | 952 | * after successful authentication |
089fbbd2 | 953 | * or if the child has died |
954 | */ | |
955 | close(startup_pipes[i]); | |
956 | startup_pipes[i] = -1; | |
957 | startups--; | |
958 | } | |
48e671d5 | 959 | for (i = 0; i < num_listen_socks; i++) { |
960 | if (!FD_ISSET(listen_socks[i], fdset)) | |
5260325f | 961 | continue; |
089fbbd2 | 962 | fromlen = sizeof(from); |
963 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
964 | &fromlen); | |
965 | if (newsock < 0) { | |
966 | if (errno != EINTR && errno != EWOULDBLOCK) | |
967 | error("accept: %.100s", strerror(errno)); | |
968 | continue; | |
969 | } | |
970 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
971 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
972 | continue; | |
973 | } | |
c345cf9d | 974 | if (drop_connection(startups) == 1) { |
975 | debug("drop connection #%d", startups); | |
089fbbd2 | 976 | close(newsock); |
977 | continue; | |
978 | } | |
979 | if (pipe(startup_p) == -1) { | |
980 | close(newsock); | |
981 | continue; | |
982 | } | |
983 | ||
984 | for (j = 0; j < options.max_startups; j++) | |
985 | if (startup_pipes[j] == -1) { | |
986 | startup_pipes[j] = startup_p[0]; | |
987 | if (maxfd < startup_p[0]) | |
988 | maxfd = startup_p[0]; | |
989 | startups++; | |
990 | break; | |
991 | } | |
992 | ||
aa3378df | 993 | /* |
089fbbd2 | 994 | * Got connection. Fork a child to handle it, unless |
995 | * we are in debugging mode. | |
aa3378df | 996 | */ |
089fbbd2 | 997 | if (debug_flag) { |
aa3378df | 998 | /* |
089fbbd2 | 999 | * In debugging mode. Close the listening |
1000 | * socket, and start processing the | |
1001 | * connection without forking. | |
aa3378df | 1002 | */ |
089fbbd2 | 1003 | debug("Server will not fork when running in debugging mode."); |
48e671d5 | 1004 | close_listen_socks(); |
5260325f | 1005 | sock_in = newsock; |
1006 | sock_out = newsock; | |
5540ea9b | 1007 | startup_pipe = -1; |
3f7a7e4a | 1008 | pid = getpid(); |
5260325f | 1009 | break; |
089fbbd2 | 1010 | } else { |
1011 | /* | |
1012 | * Normal production daemon. Fork, and have | |
1013 | * the child process the connection. The | |
1014 | * parent continues listening. | |
1015 | */ | |
1016 | if ((pid = fork()) == 0) { | |
1017 | /* | |
1018 | * Child. Close the listening and max_startup | |
1019 | * sockets. Start using the accepted socket. | |
1020 | * Reinitialize logging (since our pid has | |
1021 | * changed). We break out of the loop to handle | |
1022 | * the connection. | |
1023 | */ | |
1024 | startup_pipe = startup_p[1]; | |
1025 | for (j = 0; j < options.max_startups; j++) | |
1026 | if (startup_pipes[j] != -1) | |
1027 | close(startup_pipes[j]); | |
1028 | close_listen_socks(); | |
1029 | sock_in = newsock; | |
1030 | sock_out = newsock; | |
1fe6a48f | 1031 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
089fbbd2 | 1032 | break; |
1033 | } | |
5260325f | 1034 | } |
5260325f | 1035 | |
089fbbd2 | 1036 | /* Parent. Stay in the loop. */ |
1037 | if (pid < 0) | |
1038 | error("fork: %.100s", strerror(errno)); | |
1039 | else | |
1040 | debug("Forked child %d.", pid); | |
5260325f | 1041 | |
089fbbd2 | 1042 | close(startup_p[1]); |
5260325f | 1043 | |
089fbbd2 | 1044 | /* Mark that the key has been used (it was "given" to the child). */ |
1045 | key_used = 1; | |
5260325f | 1046 | |
089fbbd2 | 1047 | arc4random_stir(); |
1048 | ||
1049 | /* Close the new socket (the child is now taking care of it). */ | |
1050 | close(newsock); | |
1051 | } | |
48e671d5 | 1052 | /* child process check (or debug mode) */ |
1053 | if (num_listen_socks < 0) | |
1054 | break; | |
5260325f | 1055 | } |
1056 | } | |
8efc0c15 | 1057 | |
5260325f | 1058 | /* This is the child processing a new connection. */ |
1059 | ||
aa3378df | 1060 | /* |
1061 | * Disable the key regeneration alarm. We will not regenerate the | |
1062 | * key since we are no longer in a position to give it to anyone. We | |
1063 | * will not restart on SIGHUP since it no longer makes sense. | |
1064 | */ | |
5260325f | 1065 | alarm(0); |
1066 | signal(SIGALRM, SIG_DFL); | |
1067 | signal(SIGHUP, SIG_DFL); | |
1068 | signal(SIGTERM, SIG_DFL); | |
1069 | signal(SIGQUIT, SIG_DFL); | |
1070 | signal(SIGCHLD, SIG_DFL); | |
9aaf9be4 | 1071 | signal(SIGINT, SIG_DFL); |
5260325f | 1072 | |
aa3378df | 1073 | /* |
1074 | * Set socket options for the connection. We want the socket to | |
1075 | * close as fast as possible without waiting for anything. If the | |
1076 | * connection is not a socket, these will do nothing. | |
1077 | */ | |
1078 | /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 1079 | linger.l_onoff = 1; |
1080 | linger.l_linger = 5; | |
1081 | setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
1082 | ||
b5c334cc | 1083 | /* Set keepalives if requested. */ |
1084 | if (options.keepalives && | |
1085 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, | |
1086 | sizeof(on)) < 0) | |
1087 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1088 | ||
aa3378df | 1089 | /* |
1090 | * Register our connection. This turns encryption off because we do | |
1091 | * not have a key. | |
1092 | */ | |
5260325f | 1093 | packet_set_connection(sock_in, sock_out); |
1094 | ||
1095 | remote_port = get_remote_port(); | |
1096 | remote_ip = get_remote_ipaddr(); | |
1097 | ||
1098 | /* Check whether logins are denied from this host. */ | |
1099 | #ifdef LIBWRAP | |
48e671d5 | 1100 | /* XXX LIBWRAP noes not know about IPv6 */ |
5260325f | 1101 | { |
1102 | struct request_info req; | |
8efc0c15 | 1103 | |
1fe6a48f | 1104 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, NULL); |
5260325f | 1105 | fromhost(&req); |
8efc0c15 | 1106 | |
5260325f | 1107 | if (!hosts_access(&req)) { |
1108 | close(sock_in); | |
1109 | close(sock_out); | |
1110 | refuse(&req); | |
1111 | } | |
48e671d5 | 1112 | /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */ |
8efc0c15 | 1113 | } |
48e671d5 | 1114 | #endif /* LIBWRAP */ |
5260325f | 1115 | /* Log the connection. */ |
1116 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
8efc0c15 | 1117 | |
aa3378df | 1118 | /* |
1119 | * We don\'t want to listen forever unless the other side | |
1120 | * successfully authenticates itself. So we set up an alarm which is | |
1121 | * cleared after successful authentication. A limit of zero | |
1122 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1123 | * mode; it is just annoying to have the server exit just when you | |
1124 | * are about to discover the bug. | |
1125 | */ | |
5260325f | 1126 | signal(SIGALRM, grace_alarm_handler); |
1127 | if (!debug_flag) | |
1128 | alarm(options.login_grace_time); | |
1129 | ||
7368a6c8 | 1130 | sshd_exchange_identification(sock_in, sock_out); |
aa3378df | 1131 | /* |
6ffc9c88 | 1132 | * Check that the connection comes from a privileged port. |
1133 | * Rhosts-Authentication only makes sense from priviledged | |
aa3378df | 1134 | * programs. Of course, if the intruder has root access on his local |
1135 | * machine, he can connect from any port. So do not use these | |
1136 | * authentication methods from machines that you do not trust. | |
1137 | */ | |
5260325f | 1138 | if (remote_port >= IPPORT_RESERVED || |
1139 | remote_port < IPPORT_RESERVED / 2) { | |
6ffc9c88 | 1140 | debug("Rhosts Authentication disabled, " |
fa08c86b | 1141 | "originating port not trusted."); |
5260325f | 1142 | options.rhosts_authentication = 0; |
5260325f | 1143 | } |
48e671d5 | 1144 | #ifdef KRB4 |
1145 | if (!packet_connection_is_ipv4() && | |
1146 | options.kerberos_authentication) { | |
1147 | debug("Kerberos Authentication disabled, only available for IPv4."); | |
1148 | options.kerberos_authentication = 0; | |
1149 | } | |
1150 | #endif /* KRB4 */ | |
1151 | ||
5260325f | 1152 | packet_set_nonblocking(); |
1153 | ||
7b2ea3a1 | 1154 | /* perform the key exchange */ |
7b2ea3a1 | 1155 | /* authenticate user and start session */ |
e78a59f5 | 1156 | if (compat20) { |
1157 | do_ssh2_kex(); | |
1158 | do_authentication2(); | |
1159 | } else { | |
1160 | do_ssh1_kex(); | |
1161 | do_authentication(); | |
1162 | } | |
8efc0c15 | 1163 | |
1164 | #ifdef KRB4 | |
5260325f | 1165 | /* Cleanup user's ticket cache file. */ |
1166 | if (options.kerberos_ticket_cleanup) | |
1167 | (void) dest_tkt(); | |
8efc0c15 | 1168 | #endif /* KRB4 */ |
1169 | ||
5260325f | 1170 | /* The connection has been terminated. */ |
1171 | verbose("Closing connection to %.100s", remote_ip); | |
8efc0c15 | 1172 | |
d94aa2ae | 1173 | #ifdef USE_PAM |
a5c9cd31 | 1174 | finish_pam(); |
d94aa2ae | 1175 | #endif /* USE_PAM */ |
8efc0c15 | 1176 | |
5260325f | 1177 | packet_close(); |
1178 | exit(0); | |
1179 | } | |
8efc0c15 | 1180 | |
5260325f | 1181 | /* |
7b2ea3a1 | 1182 | * SSH1 key exchange |
5260325f | 1183 | */ |
e7c0f9d5 | 1184 | void |
1e3b8b07 | 1185 | do_ssh1_kex(void) |
8efc0c15 | 1186 | { |
5260325f | 1187 | int i, len; |
7b2ea3a1 | 1188 | int plen, slen; |
5260325f | 1189 | BIGNUM *session_key_int; |
1e3b8b07 | 1190 | u_char session_key[SSH_SESSION_KEY_LENGTH]; |
1191 | u_char cookie[8]; | |
1192 | u_int cipher_type, auth_mask, protocol_flags; | |
5260325f | 1193 | u_int32_t rand = 0; |
1194 | ||
aa3378df | 1195 | /* |
1196 | * Generate check bytes that the client must send back in the user | |
1197 | * packet in order for it to be accepted; this is used to defy ip | |
1198 | * spoofing attacks. Note that this only works against somebody | |
1199 | * doing IP spoofing from a remote machine; any machine on the local | |
1200 | * network can still see outgoing packets and catch the random | |
1201 | * cookie. This only affects rhosts authentication, and this is one | |
1202 | * of the reasons why it is inherently insecure. | |
1203 | */ | |
5260325f | 1204 | for (i = 0; i < 8; i++) { |
1205 | if (i % 4 == 0) | |
1206 | rand = arc4random(); | |
7b2ea3a1 | 1207 | cookie[i] = rand & 0xff; |
5260325f | 1208 | rand >>= 8; |
1209 | } | |
1210 | ||
aa3378df | 1211 | /* |
1212 | * Send our public key. We include in the packet 64 bits of random | |
1213 | * data that must be matched in the reply in order to prevent IP | |
1214 | * spoofing. | |
1215 | */ | |
5260325f | 1216 | packet_start(SSH_SMSG_PUBLIC_KEY); |
1217 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1218 | packet_put_char(cookie[i]); |
5260325f | 1219 | |
1220 | /* Store our public server RSA key. */ | |
fa08c86b | 1221 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); |
1222 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1223 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
5260325f | 1224 | |
1225 | /* Store our public host RSA key. */ | |
fa08c86b | 1226 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); |
1227 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1228 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
5260325f | 1229 | |
1230 | /* Put protocol flags. */ | |
1231 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1232 | ||
1233 | /* Declare which ciphers we support. */ | |
94ec8c6b | 1234 | packet_put_int(cipher_mask_ssh1(0)); |
5260325f | 1235 | |
1236 | /* Declare supported authentication types. */ | |
1237 | auth_mask = 0; | |
1238 | if (options.rhosts_authentication) | |
1239 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
1240 | if (options.rhosts_rsa_authentication) | |
1241 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1242 | if (options.rsa_authentication) | |
1243 | auth_mask |= 1 << SSH_AUTH_RSA; | |
8efc0c15 | 1244 | #ifdef KRB4 |
5260325f | 1245 | if (options.kerberos_authentication) |
1246 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
8efc0c15 | 1247 | #endif |
1248 | #ifdef AFS | |
5260325f | 1249 | if (options.kerberos_tgt_passing) |
1250 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
1251 | if (options.afs_token_passing) | |
1252 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
8efc0c15 | 1253 | #endif |
5260325f | 1254 | #ifdef SKEY |
1255 | if (options.skey_authentication == 1) | |
1256 | auth_mask |= 1 << SSH_AUTH_TIS; | |
1257 | #endif | |
1258 | if (options.password_authentication) | |
1259 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1260 | packet_put_int(auth_mask); | |
1261 | ||
1262 | /* Send the packet and wait for it to be sent. */ | |
1263 | packet_send(); | |
1264 | packet_write_wait(); | |
1265 | ||
fa08c86b | 1266 | debug("Sent %d bit server key and %d bit host key.", |
1267 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1268 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
5260325f | 1269 | |
1270 | /* Read clients reply (cipher type and session key). */ | |
1271 | packet_read_expect(&plen, SSH_CMSG_SESSION_KEY); | |
1272 | ||
2d86a6cc | 1273 | /* Get cipher type and check whether we accept this. */ |
5260325f | 1274 | cipher_type = packet_get_char(); |
1275 | ||
94ec8c6b | 1276 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) |
2d86a6cc | 1277 | packet_disconnect("Warning: client selects unsupported cipher."); |
1278 | ||
5260325f | 1279 | /* Get check bytes from the packet. These must match those we |
1280 | sent earlier with the public key packet. */ | |
1281 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1282 | if (cookie[i] != packet_get_char()) |
5260325f | 1283 | packet_disconnect("IP Spoofing check bytes do not match."); |
1284 | ||
1285 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1286 | ||
1287 | /* Get the encrypted integer. */ | |
1288 | session_key_int = BN_new(); | |
1289 | packet_get_bignum(session_key_int, &slen); | |
1290 | ||
5260325f | 1291 | protocol_flags = packet_get_int(); |
1292 | packet_set_protocol_flags(protocol_flags); | |
1293 | ||
1294 | packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY); | |
1295 | ||
aa3378df | 1296 | /* |
1297 | * Decrypt it using our private server key and private host key (key | |
1298 | * with larger modulus first). | |
1299 | */ | |
fa08c86b | 1300 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { |
5260325f | 1301 | /* Private key has bigger modulus. */ |
fa08c86b | 1302 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < |
1303 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1304 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1305 | get_remote_ipaddr(), | |
1306 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1307 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1308 | SSH_KEY_BITS_RESERVED); | |
5260325f | 1309 | } |
1310 | rsa_private_decrypt(session_key_int, session_key_int, | |
fa08c86b | 1311 | sensitive_data.server_key->rsa); |
5260325f | 1312 | rsa_private_decrypt(session_key_int, session_key_int, |
fa08c86b | 1313 | sensitive_data.ssh1_host_key->rsa); |
5260325f | 1314 | } else { |
1315 | /* Host key has bigger modulus (or they are equal). */ | |
fa08c86b | 1316 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < |
1317 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1318 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1319 | get_remote_ipaddr(), | |
1320 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1321 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1322 | SSH_KEY_BITS_RESERVED); | |
5260325f | 1323 | } |
1324 | rsa_private_decrypt(session_key_int, session_key_int, | |
fa08c86b | 1325 | sensitive_data.ssh1_host_key->rsa); |
5260325f | 1326 | rsa_private_decrypt(session_key_int, session_key_int, |
fa08c86b | 1327 | sensitive_data.server_key->rsa); |
5260325f | 1328 | } |
1329 | ||
7b2ea3a1 | 1330 | compute_session_id(session_id, cookie, |
fa08c86b | 1331 | sensitive_data.ssh1_host_key->rsa->n, |
1332 | sensitive_data.server_key->rsa->n); | |
5260325f | 1333 | |
7b2ea3a1 | 1334 | /* Destroy the private and public keys. They will no longer be needed. */ |
a306f2dd | 1335 | destroy_sensitive_data(); |
7b2ea3a1 | 1336 | |
aa3378df | 1337 | /* |
1338 | * Extract session key from the decrypted integer. The key is in the | |
1339 | * least significant 256 bits of the integer; the first byte of the | |
1340 | * key is in the highest bits. | |
1341 | */ | |
5260325f | 1342 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); |
1343 | len = BN_num_bytes(session_key_int); | |
1344 | if (len < 0 || len > sizeof(session_key)) | |
1345 | fatal("do_connection: bad len from %s: session_key_int %d > sizeof(session_key) %d", | |
fa08c86b | 1346 | get_remote_ipaddr(), |
1347 | len, sizeof(session_key)); | |
5260325f | 1348 | memset(session_key, 0, sizeof(session_key)); |
1349 | BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len); | |
1350 | ||
7b2ea3a1 | 1351 | /* Destroy the decrypted integer. It is no longer needed. */ |
1352 | BN_clear_free(session_key_int); | |
1353 | ||
5260325f | 1354 | /* Xor the first 16 bytes of the session key with the session id. */ |
1355 | for (i = 0; i < 16; i++) | |
1356 | session_key[i] ^= session_id[i]; | |
1357 | ||
5260325f | 1358 | /* Set the session key. From this on all communications will be encrypted. */ |
1359 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1360 | ||
1361 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1362 | memset(session_key, 0, sizeof(session_key)); | |
1363 | ||
1364 | debug("Received session key; encryption turned on."); | |
1365 | ||
1366 | /* Send an acknowledgement packet. Note that this packet is sent encrypted. */ | |
1367 | packet_start(SSH_SMSG_SUCCESS); | |
1368 | packet_send(); | |
1369 | packet_write_wait(); | |
5260325f | 1370 | } |
e78a59f5 | 1371 | |
1372 | /* | |
1373 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1374 | */ | |
1375 | void | |
1e3b8b07 | 1376 | do_ssh2_kex(void) |
e78a59f5 | 1377 | { |
1378 | Buffer *server_kexinit; | |
1379 | Buffer *client_kexinit; | |
94ec8c6b | 1380 | int payload_len; |
e78a59f5 | 1381 | int i; |
e78a59f5 | 1382 | Kex *kex; |
e78a59f5 | 1383 | char *cprop[PROPOSAL_MAX]; |
e78a59f5 | 1384 | |
1385 | /* KEXINIT */ | |
1386 | ||
a8be9f80 | 1387 | if (options.ciphers != NULL) { |
6ae2364d | 1388 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
a8be9f80 | 1389 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
1390 | } | |
fa08c86b | 1391 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
1392 | ||
71276795 | 1393 | server_kexinit = kex_init(myproposal); |
e78a59f5 | 1394 | client_kexinit = xmalloc(sizeof(*client_kexinit)); |
1395 | buffer_init(client_kexinit); | |
e78a59f5 | 1396 | |
71276795 | 1397 | /* algorithm negotiation */ |
1398 | kex_exchange_kexinit(server_kexinit, client_kexinit, cprop); | |
1399 | kex = kex_choose_conf(cprop, myproposal, 1); | |
1400 | for (i = 0; i < PROPOSAL_MAX; i++) | |
1401 | xfree(cprop[i]); | |
e78a59f5 | 1402 | |
94ec8c6b | 1403 | switch (kex->kex_type) { |
1404 | case DH_GRP1_SHA1: | |
1405 | ssh_dh1_server(kex, client_kexinit, server_kexinit); | |
1406 | break; | |
1407 | case DH_GEX_SHA1: | |
1408 | ssh_dhgex_server(kex, client_kexinit, server_kexinit); | |
1409 | break; | |
1410 | default: | |
1411 | fatal("Unsupported key exchange %d", kex->kex_type); | |
1412 | } | |
1413 | ||
1414 | debug("send SSH2_MSG_NEWKEYS."); | |
1415 | packet_start(SSH2_MSG_NEWKEYS); | |
1416 | packet_send(); | |
1417 | packet_write_wait(); | |
1418 | debug("done: send SSH2_MSG_NEWKEYS."); | |
1419 | ||
1420 | debug("Wait SSH2_MSG_NEWKEYS."); | |
1421 | packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS); | |
1422 | debug("GOT SSH2_MSG_NEWKEYS."); | |
1423 | ||
1424 | #ifdef DEBUG_KEXDH | |
1425 | /* send 1st encrypted/maced/compressed message */ | |
1426 | packet_start(SSH2_MSG_IGNORE); | |
1427 | packet_put_cstring("markus"); | |
1428 | packet_send(); | |
1429 | packet_write_wait(); | |
1430 | #endif | |
1431 | ||
1432 | debug("done: KEX2."); | |
1433 | } | |
1434 | ||
1435 | /* | |
1436 | * SSH2 key exchange | |
1437 | */ | |
1438 | ||
1439 | /* diffie-hellman-group1-sha1 */ | |
1440 | ||
1441 | void | |
1442 | ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit) | |
1443 | { | |
1444 | #ifdef DEBUG_KEXDH | |
1445 | int i; | |
1446 | #endif | |
1447 | int payload_len, dlen; | |
1448 | int slen; | |
1e3b8b07 | 1449 | u_char *signature = NULL; |
1450 | u_char *server_host_key_blob = NULL; | |
1451 | u_int sbloblen; | |
1452 | u_int klen, kout; | |
1453 | u_char *kbuf; | |
1454 | u_char *hash; | |
94ec8c6b | 1455 | BIGNUM *shared_secret = 0; |
1456 | DH *dh; | |
1457 | BIGNUM *dh_client_pub = 0; | |
fa08c86b | 1458 | Key *hostkey; |
1459 | ||
1460 | hostkey = get_hostkey_by_type(kex->hostkey_type); | |
1461 | if (hostkey == NULL) | |
1462 | fatal("Unsupported hostkey type %d", kex->hostkey_type); | |
e78a59f5 | 1463 | |
94ec8c6b | 1464 | /* KEXDH */ |
3e1caa83 | 1465 | /* generate DH key */ |
1466 | dh = dh_new_group1(); /* XXX depends on 'kex' */ | |
1467 | dh_gen_key(dh); | |
1468 | ||
e78a59f5 | 1469 | debug("Wait SSH2_MSG_KEXDH_INIT."); |
1470 | packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT); | |
1471 | ||
1472 | /* key, cert */ | |
1473 | dh_client_pub = BN_new(); | |
1474 | if (dh_client_pub == NULL) | |
1475 | fatal("dh_client_pub == NULL"); | |
1476 | packet_get_bignum2(dh_client_pub, &dlen); | |
1477 | ||
1478 | #ifdef DEBUG_KEXDH | |
1479 | fprintf(stderr, "\ndh_client_pub= "); | |
188adeb2 | 1480 | BN_print_fp(stderr, dh_client_pub); |
e78a59f5 | 1481 | fprintf(stderr, "\n"); |
1482 | debug("bits %d", BN_num_bits(dh_client_pub)); | |
1483 | #endif | |
1484 | ||
e78a59f5 | 1485 | #ifdef DEBUG_KEXDH |
1486 | fprintf(stderr, "\np= "); | |
188adeb2 | 1487 | BN_print_fp(stderr, dh->p); |
e78a59f5 | 1488 | fprintf(stderr, "\ng= "); |
188adeb2 | 1489 | bn_print(dh->g); |
e78a59f5 | 1490 | fprintf(stderr, "\npub= "); |
188adeb2 | 1491 | BN_print_fp(stderr, dh->pub_key); |
e78a59f5 | 1492 | fprintf(stderr, "\n"); |
188adeb2 | 1493 | DHparams_print_fp(stderr, dh); |
e78a59f5 | 1494 | #endif |
a8be9f80 | 1495 | if (!dh_pub_is_valid(dh, dh_client_pub)) |
1496 | packet_disconnect("bad client public DH value"); | |
e78a59f5 | 1497 | |
1498 | klen = DH_size(dh); | |
1499 | kbuf = xmalloc(klen); | |
1500 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | |
1501 | ||
1502 | #ifdef DEBUG_KEXDH | |
1503 | debug("shared secret: len %d/%d", klen, kout); | |
1504 | fprintf(stderr, "shared secret == "); | |
1505 | for (i = 0; i< kout; i++) | |
1506 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
1507 | fprintf(stderr, "\n"); | |
1508 | #endif | |
1509 | shared_secret = BN_new(); | |
1510 | ||
1511 | BN_bin2bn(kbuf, kout, shared_secret); | |
1512 | memset(kbuf, 0, klen); | |
1513 | xfree(kbuf); | |
1514 | ||
a306f2dd | 1515 | /* XXX precompute? */ |
fa08c86b | 1516 | key_to_blob(hostkey, &server_host_key_blob, &sbloblen); |
e78a59f5 | 1517 | |
1518 | /* calc H */ /* XXX depends on 'kex' */ | |
1519 | hash = kex_hash( | |
1520 | client_version_string, | |
1521 | server_version_string, | |
1522 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
1523 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
1524 | (char *)server_host_key_blob, sbloblen, | |
1525 | dh_client_pub, | |
1526 | dh->pub_key, | |
1527 | shared_secret | |
1528 | ); | |
1529 | buffer_free(client_kexinit); | |
1530 | buffer_free(server_kexinit); | |
1531 | xfree(client_kexinit); | |
1532 | xfree(server_kexinit); | |
1533 | #ifdef DEBUG_KEXDH | |
6ae2364d | 1534 | fprintf(stderr, "hash == "); |
1535 | for (i = 0; i< 20; i++) | |
1536 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
1537 | fprintf(stderr, "\n"); | |
e78a59f5 | 1538 | #endif |
a306f2dd | 1539 | /* save session id := H */ |
1540 | /* XXX hashlen depends on KEX */ | |
1541 | session_id2_len = 20; | |
1542 | session_id2 = xmalloc(session_id2_len); | |
1543 | memcpy(session_id2, hash, session_id2_len); | |
1544 | ||
e78a59f5 | 1545 | /* sign H */ |
a306f2dd | 1546 | /* XXX hashlen depends on KEX */ |
fa08c86b | 1547 | key_sign(hostkey, &signature, &slen, hash, 20); |
a306f2dd | 1548 | |
1549 | destroy_sensitive_data(); | |
e78a59f5 | 1550 | |
1551 | /* send server hostkey, DH pubkey 'f' and singed H */ | |
1552 | packet_start(SSH2_MSG_KEXDH_REPLY); | |
1553 | packet_put_string((char *)server_host_key_blob, sbloblen); | |
1d1ffb87 | 1554 | packet_put_bignum2(dh->pub_key); /* f */ |
e78a59f5 | 1555 | packet_put_string((char *)signature, slen); |
1556 | packet_send(); | |
d6f24e45 | 1557 | xfree(signature); |
a306f2dd | 1558 | xfree(server_host_key_blob); |
e78a59f5 | 1559 | packet_write_wait(); |
1560 | ||
1561 | kex_derive_keys(kex, hash, shared_secret); | |
1562 | packet_set_kex(kex); | |
1563 | ||
1564 | /* have keys, free DH */ | |
1565 | DH_free(dh); | |
94ec8c6b | 1566 | } |
e78a59f5 | 1567 | |
94ec8c6b | 1568 | /* diffie-hellman-group-exchange-sha1 */ |
1569 | ||
1570 | void | |
1571 | ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit) | |
1572 | { | |
1573 | #ifdef DEBUG_KEXDH | |
1574 | int i; | |
1575 | #endif | |
1576 | int payload_len, dlen; | |
1577 | int slen, nbits; | |
1e3b8b07 | 1578 | u_char *signature = NULL; |
1579 | u_char *server_host_key_blob = NULL; | |
1580 | u_int sbloblen; | |
1581 | u_int klen, kout; | |
1582 | u_char *kbuf; | |
1583 | u_char *hash; | |
94ec8c6b | 1584 | BIGNUM *shared_secret = 0; |
1585 | DH *dh; | |
1586 | BIGNUM *dh_client_pub = 0; | |
fa08c86b | 1587 | Key *hostkey; |
1588 | ||
1589 | hostkey = get_hostkey_by_type(kex->hostkey_type); | |
1590 | if (hostkey == NULL) | |
1591 | fatal("Unsupported hostkey type %d", kex->hostkey_type); | |
94ec8c6b | 1592 | |
1593 | /* KEXDHGEX */ | |
1594 | debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST."); | |
1595 | packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_REQUEST); | |
1596 | nbits = packet_get_int(); | |
1597 | dh = choose_dh(nbits); | |
1598 | ||
1599 | debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP."); | |
1600 | packet_start(SSH2_MSG_KEX_DH_GEX_GROUP); | |
1601 | packet_put_bignum2(dh->p); | |
1602 | packet_put_bignum2(dh->g); | |
e78a59f5 | 1603 | packet_send(); |
1604 | packet_write_wait(); | |
e78a59f5 | 1605 | |
3e1caa83 | 1606 | /* Compute our exchange value in parallel with the client */ |
1607 | ||
1608 | dh_gen_key(dh); | |
1609 | ||
94ec8c6b | 1610 | debug("Wait SSH2_MSG_KEX_DH_GEX_INIT."); |
1611 | packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_INIT); | |
1612 | ||
1613 | /* key, cert */ | |
1614 | dh_client_pub = BN_new(); | |
1615 | if (dh_client_pub == NULL) | |
1616 | fatal("dh_client_pub == NULL"); | |
1617 | packet_get_bignum2(dh_client_pub, &dlen); | |
e78a59f5 | 1618 | |
a8be9f80 | 1619 | #ifdef DEBUG_KEXDH |
94ec8c6b | 1620 | fprintf(stderr, "\ndh_client_pub= "); |
1621 | BN_print_fp(stderr, dh_client_pub); | |
1622 | fprintf(stderr, "\n"); | |
1623 | debug("bits %d", BN_num_bits(dh_client_pub)); | |
1624 | #endif | |
1625 | ||
1626 | #ifdef DEBUG_KEXDH | |
1627 | fprintf(stderr, "\np= "); | |
1628 | BN_print_fp(stderr, dh->p); | |
1629 | fprintf(stderr, "\ng= "); | |
1630 | bn_print(dh->g); | |
1631 | fprintf(stderr, "\npub= "); | |
1632 | BN_print_fp(stderr, dh->pub_key); | |
1633 | fprintf(stderr, "\n"); | |
1634 | DHparams_print_fp(stderr, dh); | |
1635 | #endif | |
1636 | if (!dh_pub_is_valid(dh, dh_client_pub)) | |
1637 | packet_disconnect("bad client public DH value"); | |
1638 | ||
1639 | klen = DH_size(dh); | |
1640 | kbuf = xmalloc(klen); | |
1641 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | |
1642 | ||
1643 | #ifdef DEBUG_KEXDH | |
1644 | debug("shared secret: len %d/%d", klen, kout); | |
1645 | fprintf(stderr, "shared secret == "); | |
1646 | for (i = 0; i< kout; i++) | |
1647 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
1648 | fprintf(stderr, "\n"); | |
1649 | #endif | |
1650 | shared_secret = BN_new(); | |
1651 | ||
1652 | BN_bin2bn(kbuf, kout, shared_secret); | |
1653 | memset(kbuf, 0, klen); | |
1654 | xfree(kbuf); | |
1655 | ||
1656 | /* XXX precompute? */ | |
fa08c86b | 1657 | key_to_blob(hostkey, &server_host_key_blob, &sbloblen); |
94ec8c6b | 1658 | |
1659 | /* calc H */ /* XXX depends on 'kex' */ | |
1660 | hash = kex_hash_gex( | |
1661 | client_version_string, | |
1662 | server_version_string, | |
1663 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
1664 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
1665 | (char *)server_host_key_blob, sbloblen, | |
1666 | nbits, dh->p, dh->g, | |
1667 | dh_client_pub, | |
1668 | dh->pub_key, | |
1669 | shared_secret | |
1670 | ); | |
1671 | buffer_free(client_kexinit); | |
1672 | buffer_free(server_kexinit); | |
1673 | xfree(client_kexinit); | |
1674 | xfree(server_kexinit); | |
1675 | #ifdef DEBUG_KEXDH | |
1676 | fprintf(stderr, "hash == "); | |
1677 | for (i = 0; i< 20; i++) | |
1678 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
1679 | fprintf(stderr, "\n"); | |
1680 | #endif | |
1681 | /* save session id := H */ | |
1682 | /* XXX hashlen depends on KEX */ | |
1683 | session_id2_len = 20; | |
1684 | session_id2 = xmalloc(session_id2_len); | |
1685 | memcpy(session_id2, hash, session_id2_len); | |
1686 | ||
1687 | /* sign H */ | |
1688 | /* XXX hashlen depends on KEX */ | |
fa08c86b | 1689 | key_sign(hostkey, &signature, &slen, hash, 20); |
94ec8c6b | 1690 | |
1691 | destroy_sensitive_data(); | |
1692 | ||
1693 | /* send server hostkey, DH pubkey 'f' and singed H */ | |
1694 | packet_start(SSH2_MSG_KEX_DH_GEX_REPLY); | |
1695 | packet_put_string((char *)server_host_key_blob, sbloblen); | |
1696 | packet_put_bignum2(dh->pub_key); /* f */ | |
1697 | packet_put_string((char *)signature, slen); | |
e78a59f5 | 1698 | packet_send(); |
94ec8c6b | 1699 | xfree(signature); |
1700 | xfree(server_host_key_blob); | |
e78a59f5 | 1701 | packet_write_wait(); |
94ec8c6b | 1702 | |
1703 | kex_derive_keys(kex, hash, shared_secret); | |
1704 | packet_set_kex(kex); | |
1705 | ||
1706 | /* have keys, free DH */ | |
1707 | DH_free(dh); | |
e78a59f5 | 1708 | } |