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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" | |
0572fe75 | 43 | RCSID("$OpenBSD: sshd.c,v 1.170 2001/02/28 21:21:41 markus Exp $"); |
8efc0c15 | 44 | |
42f11eb2 | 45 | #include <openssl/dh.h> |
46 | #include <openssl/bn.h> | |
47 | #include <openssl/hmac.h> | |
48 | ||
49 | #include "ssh.h" | |
50 | #include "ssh1.h" | |
51 | #include "ssh2.h" | |
8efc0c15 | 52 | #include "xmalloc.h" |
53 | #include "rsa.h" | |
1729c161 | 54 | #include "sshpty.h" |
8efc0c15 | 55 | #include "packet.h" |
8efc0c15 | 56 | #include "mpaux.h" |
42f11eb2 | 57 | #include "log.h" |
8efc0c15 | 58 | #include "servconf.h" |
59 | #include "uidswap.h" | |
60 | #include "compat.h" | |
7368a6c8 | 61 | #include "buffer.h" |
42f11eb2 | 62 | #include "cipher.h" |
e78a59f5 | 63 | #include "kex.h" |
7368a6c8 | 64 | #include "key.h" |
94ec8c6b | 65 | #include "dh.h" |
e78a59f5 | 66 | #include "myproposal.h" |
a306f2dd | 67 | #include "authfile.h" |
42f11eb2 | 68 | #include "pathnames.h" |
69 | #include "atomicio.h" | |
70 | #include "canohost.h" | |
71 | #include "auth.h" | |
72 | #include "misc.h" | |
8efc0c15 | 73 | |
74 | #ifdef LIBWRAP | |
75 | #include <tcpd.h> | |
76 | #include <syslog.h> | |
77 | int allow_severity = LOG_INFO; | |
78 | int deny_severity = LOG_WARNING; | |
79 | #endif /* LIBWRAP */ | |
80 | ||
81 | #ifndef O_NOCTTY | |
82 | #define O_NOCTTY 0 | |
83 | #endif | |
84 | ||
260d427b | 85 | #ifdef HAVE___PROGNAME |
86 | extern char *__progname; | |
87 | #else | |
88 | char *__progname; | |
89 | #endif | |
90 | ||
8efc0c15 | 91 | /* Server configuration options. */ |
92 | ServerOptions options; | |
93 | ||
94 | /* Name of the server configuration file. */ | |
42f11eb2 | 95 | char *config_file_name = _PATH_SERVER_CONFIG_FILE; |
8efc0c15 | 96 | |
6ae2364d | 97 | /* |
48e671d5 | 98 | * Flag indicating whether IPv4 or IPv6. This can be set on the command line. |
99 | * Default value is AF_UNSPEC means both IPv4 and IPv6. | |
100 | */ | |
59e76f33 | 101 | #ifdef IPV4_DEFAULT |
102 | int IPv4or6 = AF_INET; | |
103 | #else | |
48e671d5 | 104 | int IPv4or6 = AF_UNSPEC; |
59e76f33 | 105 | #endif |
48e671d5 | 106 | |
5260325f | 107 | /* |
108 | * Debug mode flag. This can be set on the command line. If debug | |
109 | * mode is enabled, extra debugging output will be sent to the system | |
110 | * log, the daemon will not go to background, and will exit after processing | |
111 | * the first connection. | |
112 | */ | |
8efc0c15 | 113 | int debug_flag = 0; |
114 | ||
115 | /* Flag indicating that the daemon is being started from inetd. */ | |
116 | int inetd_flag = 0; | |
117 | ||
0b6fbf03 | 118 | /* Flag indicating that sshd should not detach and become a daemon. */ |
119 | int no_daemon_flag = 0; | |
120 | ||
6a17f9c2 | 121 | /* debug goes to stderr unless inetd_flag is set */ |
122 | int log_stderr = 0; | |
123 | ||
8efc0c15 | 124 | /* Saved arguments to main(). */ |
125 | char **saved_argv; | |
4d33e531 | 126 | int saved_argc; |
8efc0c15 | 127 | |
aa3378df | 128 | /* |
48e671d5 | 129 | * The sockets that the server is listening; this is used in the SIGHUP |
130 | * signal handler. | |
aa3378df | 131 | */ |
48e671d5 | 132 | #define MAX_LISTEN_SOCKS 16 |
133 | int listen_socks[MAX_LISTEN_SOCKS]; | |
134 | int num_listen_socks = 0; | |
8efc0c15 | 135 | |
aa3378df | 136 | /* |
137 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
138 | * sshd will skip the version-number exchange | |
139 | */ | |
5260325f | 140 | char *client_version_string = NULL; |
7368a6c8 | 141 | char *server_version_string = NULL; |
8efc0c15 | 142 | |
aa3378df | 143 | /* |
144 | * Any really sensitive data in the application is contained in this | |
145 | * structure. The idea is that this structure could be locked into memory so | |
146 | * that the pages do not get written into swap. However, there are some | |
147 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
148 | * have access to the internals of them, and locking just the structure is | |
149 | * not very useful. Currently, memory locking is not implemented. | |
150 | */ | |
5260325f | 151 | struct { |
fa08c86b | 152 | Key *server_key; /* empheral server key */ |
153 | Key *ssh1_host_key; /* ssh1 host key */ | |
154 | Key **host_keys; /* all private host keys */ | |
155 | int have_ssh1_key; | |
156 | int have_ssh2_key; | |
00be5382 | 157 | u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; |
8efc0c15 | 158 | } sensitive_data; |
159 | ||
aa3378df | 160 | /* |
59c97189 | 161 | * Flag indicating whether the RSA server key needs to be regenerated. |
162 | * Is set in the SIGALRM handler and cleared when the key is regenerated. | |
aa3378df | 163 | */ |
59c97189 | 164 | int key_do_regen = 0; |
8efc0c15 | 165 | |
166 | /* This is set to true when SIGHUP is received. */ | |
167 | int received_sighup = 0; | |
168 | ||
7368a6c8 | 169 | /* session identifier, used by RSA-auth */ |
1e3b8b07 | 170 | u_char session_id[16]; |
e7c0f9d5 | 171 | |
a306f2dd | 172 | /* same for ssh2 */ |
1e3b8b07 | 173 | u_char *session_id2 = NULL; |
a306f2dd | 174 | int session_id2_len = 0; |
175 | ||
c345cf9d | 176 | /* record remote hostname or ip */ |
1e3b8b07 | 177 | u_int utmp_len = MAXHOSTNAMELEN; |
c345cf9d | 178 | |
7368a6c8 | 179 | /* Prototypes for various functions defined later in this file. */ |
1e3b8b07 | 180 | void do_ssh1_kex(void); |
181 | void do_ssh2_kex(void); | |
c8d54615 | 182 | |
94ec8c6b | 183 | void ssh_dh1_server(Kex *, Buffer *_kexinit, Buffer *); |
184 | void ssh_dhgex_server(Kex *, Buffer *_kexinit, Buffer *); | |
185 | ||
48e671d5 | 186 | /* |
187 | * Close all listening sockets | |
188 | */ | |
189 | void | |
190 | close_listen_socks(void) | |
191 | { | |
192 | int i; | |
193 | for (i = 0; i < num_listen_socks; i++) | |
194 | close(listen_socks[i]); | |
195 | num_listen_socks = -1; | |
196 | } | |
197 | ||
5260325f | 198 | /* |
199 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
200 | * the effect is to reread the configuration file (and to regenerate | |
201 | * the server key). | |
202 | */ | |
6ae2364d | 203 | void |
5260325f | 204 | sighup_handler(int sig) |
8efc0c15 | 205 | { |
5260325f | 206 | received_sighup = 1; |
207 | signal(SIGHUP, sighup_handler); | |
8efc0c15 | 208 | } |
209 | ||
5260325f | 210 | /* |
211 | * Called from the main program after receiving SIGHUP. | |
212 | * Restarts the server. | |
213 | */ | |
6ae2364d | 214 | void |
5ca51e19 | 215 | sighup_restart(void) |
8efc0c15 | 216 | { |
5260325f | 217 | log("Received SIGHUP; restarting."); |
48e671d5 | 218 | close_listen_socks(); |
5260325f | 219 | execv(saved_argv[0], saved_argv); |
1fe6a48f | 220 | log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno)); |
5260325f | 221 | exit(1); |
8efc0c15 | 222 | } |
223 | ||
5260325f | 224 | /* |
225 | * Generic signal handler for terminating signals in the master daemon. | |
226 | * These close the listen socket; not closing it seems to cause "Address | |
227 | * already in use" problems on some machines, which is inconvenient. | |
228 | */ | |
6ae2364d | 229 | void |
5260325f | 230 | sigterm_handler(int sig) |
8efc0c15 | 231 | { |
5260325f | 232 | log("Received signal %d; terminating.", sig); |
48e671d5 | 233 | close_listen_socks(); |
0fbe8c74 | 234 | unlink(options.pid_file); |
5260325f | 235 | exit(255); |
8efc0c15 | 236 | } |
237 | ||
5260325f | 238 | /* |
239 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
240 | * reap any zombies left by exited c. | |
241 | */ | |
6ae2364d | 242 | void |
5260325f | 243 | main_sigchld_handler(int sig) |
8efc0c15 | 244 | { |
5260325f | 245 | int save_errno = errno; |
246 | int status; | |
5ad13cd7 | 247 | |
5260325f | 248 | while (waitpid(-1, &status, WNOHANG) > 0) |
249 | ; | |
5ad13cd7 | 250 | |
5260325f | 251 | signal(SIGCHLD, main_sigchld_handler); |
252 | errno = save_errno; | |
8efc0c15 | 253 | } |
254 | ||
5260325f | 255 | /* |
256 | * Signal handler for the alarm after the login grace period has expired. | |
257 | */ | |
6ae2364d | 258 | void |
5260325f | 259 | grace_alarm_handler(int sig) |
8efc0c15 | 260 | { |
5260325f | 261 | /* Close the connection. */ |
262 | packet_close(); | |
8efc0c15 | 263 | |
5260325f | 264 | /* Log error and exit. */ |
265 | fatal("Timeout before authentication for %s.", get_remote_ipaddr()); | |
266 | } | |
8efc0c15 | 267 | |
5260325f | 268 | /* |
269 | * Signal handler for the key regeneration alarm. Note that this | |
270 | * alarm only occurs in the daemon waiting for connections, and it does not | |
271 | * do anything with the private key or random state before forking. | |
272 | * Thus there should be no concurrency control/asynchronous execution | |
273 | * problems. | |
274 | */ | |
6ae2364d | 275 | void |
fa08c86b | 276 | generate_empheral_server_key(void) |
277 | { | |
00be5382 | 278 | u_int32_t rand = 0; |
279 | int i; | |
280 | ||
fa08c86b | 281 | log("Generating %s%d bit RSA key.", sensitive_data.server_key ? "new " : "", |
282 | options.server_key_bits); | |
283 | if (sensitive_data.server_key != NULL) | |
284 | key_free(sensitive_data.server_key); | |
285 | sensitive_data.server_key = key_generate(KEY_RSA1, options.server_key_bits); | |
fa08c86b | 286 | log("RSA key generation complete."); |
00be5382 | 287 | |
288 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
289 | if (i % 4 == 0) | |
290 | rand = arc4random(); | |
291 | sensitive_data.ssh1_cookie[i] = rand & 0xff; | |
292 | rand >>= 8; | |
293 | } | |
294 | arc4random_stir(); | |
fa08c86b | 295 | } |
f546c780 | 296 | |
fa08c86b | 297 | void |
5260325f | 298 | key_regeneration_alarm(int sig) |
299 | { | |
300 | int save_errno = errno; | |
59c97189 | 301 | signal(SIGALRM, SIG_DFL); |
5260325f | 302 | errno = save_errno; |
59c97189 | 303 | key_do_regen = 1; |
5260325f | 304 | } |
8efc0c15 | 305 | |
7368a6c8 | 306 | void |
307 | sshd_exchange_identification(int sock_in, int sock_out) | |
308 | { | |
a8be9f80 | 309 | int i, mismatch; |
7368a6c8 | 310 | int remote_major, remote_minor; |
a8be9f80 | 311 | int major, minor; |
7368a6c8 | 312 | char *s; |
313 | char buf[256]; /* Must not be larger than remote_version. */ | |
314 | char remote_version[256]; /* Must be at least as big as buf. */ | |
315 | ||
a8be9f80 | 316 | if ((options.protocol & SSH_PROTO_1) && |
317 | (options.protocol & SSH_PROTO_2)) { | |
318 | major = PROTOCOL_MAJOR_1; | |
319 | minor = 99; | |
320 | } else if (options.protocol & SSH_PROTO_2) { | |
321 | major = PROTOCOL_MAJOR_2; | |
322 | minor = PROTOCOL_MINOR_2; | |
323 | } else { | |
324 | major = PROTOCOL_MAJOR_1; | |
325 | minor = PROTOCOL_MINOR_1; | |
326 | } | |
327 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
7368a6c8 | 328 | server_version_string = xstrdup(buf); |
329 | ||
330 | if (client_version_string == NULL) { | |
331 | /* Send our protocol version identification. */ | |
332 | if (atomicio(write, sock_out, server_version_string, strlen(server_version_string)) | |
333 | != strlen(server_version_string)) { | |
334 | log("Could not write ident string to %s.", get_remote_ipaddr()); | |
335 | fatal_cleanup(); | |
336 | } | |
337 | ||
2ce1adf9 | 338 | /* Read other side's version identification. */ |
339 | memset(buf, 0, sizeof(buf)); | |
7368a6c8 | 340 | for (i = 0; i < sizeof(buf) - 1; i++) { |
e5a0294f | 341 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { |
c2b544a5 | 342 | log("Did not receive identification string from %s.", |
343 | get_remote_ipaddr()); | |
7368a6c8 | 344 | fatal_cleanup(); |
345 | } | |
346 | if (buf[i] == '\r') { | |
347 | buf[i] = '\n'; | |
348 | buf[i + 1] = 0; | |
94ec8c6b | 349 | /* Kludge for F-Secure Macintosh < 1.0.2 */ |
350 | if (i == 12 && | |
351 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
352 | break; | |
7368a6c8 | 353 | continue; |
7368a6c8 | 354 | } |
355 | if (buf[i] == '\n') { | |
356 | /* buf[i] == '\n' */ | |
357 | buf[i + 1] = 0; | |
358 | break; | |
359 | } | |
360 | } | |
361 | buf[sizeof(buf) - 1] = 0; | |
362 | client_version_string = xstrdup(buf); | |
363 | } | |
364 | ||
365 | /* | |
366 | * Check that the versions match. In future this might accept | |
367 | * several versions and set appropriate flags to handle them. | |
368 | */ | |
369 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
370 | &remote_major, &remote_minor, remote_version) != 3) { | |
6ae2364d | 371 | s = "Protocol mismatch.\n"; |
7368a6c8 | 372 | (void) atomicio(write, sock_out, s, strlen(s)); |
373 | close(sock_in); | |
374 | close(sock_out); | |
375 | log("Bad protocol version identification '%.100s' from %s", | |
376 | client_version_string, get_remote_ipaddr()); | |
377 | fatal_cleanup(); | |
378 | } | |
379 | debug("Client protocol version %d.%d; client software version %.100s", | |
380 | remote_major, remote_minor, remote_version); | |
381 | ||
e78a59f5 | 382 | compat_datafellows(remote_version); |
383 | ||
a8be9f80 | 384 | mismatch = 0; |
7368a6c8 | 385 | switch(remote_major) { |
386 | case 1: | |
a306f2dd | 387 | if (remote_minor == 99) { |
388 | if (options.protocol & SSH_PROTO_2) | |
389 | enable_compat20(); | |
390 | else | |
391 | mismatch = 1; | |
392 | break; | |
393 | } | |
a8be9f80 | 394 | if (!(options.protocol & SSH_PROTO_1)) { |
395 | mismatch = 1; | |
396 | break; | |
397 | } | |
7368a6c8 | 398 | if (remote_minor < 3) { |
089fbbd2 | 399 | packet_disconnect("Your ssh version is too old and " |
7368a6c8 | 400 | "is no longer supported. Please install a newer version."); |
401 | } else if (remote_minor == 3) { | |
402 | /* note that this disables agent-forwarding */ | |
403 | enable_compat13(); | |
404 | } | |
a8be9f80 | 405 | break; |
e78a59f5 | 406 | case 2: |
a8be9f80 | 407 | if (options.protocol & SSH_PROTO_2) { |
e78a59f5 | 408 | enable_compat20(); |
409 | break; | |
410 | } | |
411 | /* FALLTHROUGH */ | |
6ae2364d | 412 | default: |
a8be9f80 | 413 | mismatch = 1; |
414 | break; | |
415 | } | |
416 | chop(server_version_string); | |
417 | chop(client_version_string); | |
418 | debug("Local version string %.200s", server_version_string); | |
419 | ||
420 | if (mismatch) { | |
7368a6c8 | 421 | s = "Protocol major versions differ.\n"; |
422 | (void) atomicio(write, sock_out, s, strlen(s)); | |
423 | close(sock_in); | |
424 | close(sock_out); | |
a8be9f80 | 425 | log("Protocol major versions differ for %s: %.200s vs. %.200s", |
426 | get_remote_ipaddr(), | |
427 | server_version_string, client_version_string); | |
7368a6c8 | 428 | fatal_cleanup(); |
7368a6c8 | 429 | } |
a306f2dd | 430 | if (compat20) |
431 | packet_set_ssh2_format(); | |
432 | } | |
433 | ||
434 | ||
fa08c86b | 435 | /* Destroy the host and server keys. They will no longer be needed. */ |
a306f2dd | 436 | void |
437 | destroy_sensitive_data(void) | |
438 | { | |
fa08c86b | 439 | int i; |
440 | ||
441 | if (sensitive_data.server_key) { | |
442 | key_free(sensitive_data.server_key); | |
443 | sensitive_data.server_key = NULL; | |
444 | } | |
2b87da3b | 445 | for(i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 446 | if (sensitive_data.host_keys[i]) { |
447 | key_free(sensitive_data.host_keys[i]); | |
448 | sensitive_data.host_keys[i] = NULL; | |
449 | } | |
450 | } | |
451 | sensitive_data.ssh1_host_key = NULL; | |
00be5382 | 452 | memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); |
fa08c86b | 453 | } |
454 | Key * | |
455 | load_private_key_autodetect(const char *filename) | |
456 | { | |
457 | struct stat st; | |
458 | int type; | |
459 | Key *public, *private; | |
460 | ||
461 | if (stat(filename, &st) < 0) { | |
462 | perror(filename); | |
463 | return NULL; | |
464 | } | |
465 | /* | |
466 | * try to load the public key. right now this only works for RSA1, | |
467 | * since SSH2 keys are fully encrypted | |
468 | */ | |
469 | type = KEY_RSA1; | |
470 | public = key_new(type); | |
471 | if (!load_public_key(filename, public, NULL)) { | |
472 | /* ok, so we will assume this is 'some' key */ | |
473 | type = KEY_UNSPEC; | |
474 | } | |
475 | key_free(public); | |
476 | ||
477 | /* Ok, try key with empty passphrase */ | |
478 | private = key_new(type); | |
479 | if (load_private_key(filename, "", private, NULL)) { | |
480 | debug("load_private_key_autodetect: type %d %s", | |
481 | private->type, key_type(private)); | |
482 | return private; | |
483 | } | |
484 | key_free(private); | |
485 | return NULL; | |
486 | } | |
487 | ||
488 | char * | |
489 | list_hostkey_types(void) | |
490 | { | |
491 | static char buf[1024]; | |
492 | int i; | |
493 | buf[0] = '\0'; | |
494 | for(i = 0; i < options.num_host_key_files; i++) { | |
495 | Key *key = sensitive_data.host_keys[i]; | |
496 | if (key == NULL) | |
497 | continue; | |
498 | switch(key->type) { | |
499 | case KEY_RSA: | |
500 | case KEY_DSA: | |
501 | strlcat(buf, key_ssh_name(key), sizeof buf); | |
502 | strlcat(buf, ",", sizeof buf); | |
503 | break; | |
504 | } | |
505 | } | |
506 | i = strlen(buf); | |
507 | if (i > 0 && buf[i-1] == ',') | |
508 | buf[i-1] = '\0'; | |
509 | debug("list_hostkey_types: %s", buf); | |
510 | return buf; | |
511 | } | |
512 | ||
513 | Key * | |
514 | get_hostkey_by_type(int type) | |
515 | { | |
516 | int i; | |
517 | for(i = 0; i < options.num_host_key_files; i++) { | |
518 | Key *key = sensitive_data.host_keys[i]; | |
519 | if (key != NULL && key->type == type) | |
520 | return key; | |
521 | } | |
522 | return NULL; | |
7368a6c8 | 523 | } |
524 | ||
c345cf9d | 525 | /* |
526 | * returns 1 if connection should be dropped, 0 otherwise. | |
527 | * dropping starts at connection #max_startups_begin with a probability | |
528 | * of (max_startups_rate/100). the probability increases linearly until | |
529 | * all connections are dropped for startups > max_startups | |
530 | */ | |
531 | int | |
532 | drop_connection(int startups) | |
533 | { | |
534 | double p, r; | |
535 | ||
536 | if (startups < options.max_startups_begin) | |
537 | return 0; | |
538 | if (startups >= options.max_startups) | |
539 | return 1; | |
540 | if (options.max_startups_rate == 100) | |
541 | return 1; | |
542 | ||
543 | p = 100 - options.max_startups_rate; | |
544 | p *= startups - options.max_startups_begin; | |
545 | p /= (double) (options.max_startups - options.max_startups_begin); | |
546 | p += options.max_startups_rate; | |
547 | p /= 100.0; | |
548 | r = arc4random() / (double) UINT_MAX; | |
549 | ||
550 | debug("drop_connection: p %g, r %g", p, r); | |
551 | return (r < p) ? 1 : 0; | |
552 | } | |
553 | ||
089fbbd2 | 554 | int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */ |
555 | int startup_pipe; /* in child */ | |
556 | ||
5260325f | 557 | /* |
558 | * Main program for the daemon. | |
559 | */ | |
8efc0c15 | 560 | int |
561 | main(int ac, char **av) | |
562 | { | |
5260325f | 563 | extern char *optarg; |
564 | extern int optind; | |
089fbbd2 | 565 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; |
9da5c3c9 | 566 | pid_t pid; |
48e671d5 | 567 | socklen_t fromlen; |
48e671d5 | 568 | fd_set *fdset; |
569 | struct sockaddr_storage from; | |
5260325f | 570 | const char *remote_ip; |
571 | int remote_port; | |
5260325f | 572 | FILE *f; |
573 | struct linger linger; | |
48e671d5 | 574 | struct addrinfo *ai; |
575 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
576 | int listen_sock, maxfd; | |
089fbbd2 | 577 | int startup_p[2]; |
578 | int startups = 0; | |
59c97189 | 579 | int ret, key_used = 0; |
5260325f | 580 | |
260d427b | 581 | __progname = get_progname(av[0]); |
264dce47 | 582 | init_rng(); |
583 | ||
1fe6a48f | 584 | /* Save argv. */ |
4d33e531 | 585 | saved_argc = ac; |
5260325f | 586 | saved_argv = av; |
5260325f | 587 | |
588 | /* Initialize configuration options to their default values. */ | |
589 | initialize_server_options(&options); | |
590 | ||
591 | /* Parse command-line arguments. */ | |
b5c334cc | 592 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:dDiqQ46")) != -1) { |
5260325f | 593 | switch (opt) { |
48e671d5 | 594 | case '4': |
595 | IPv4or6 = AF_INET; | |
596 | break; | |
597 | case '6': | |
598 | IPv4or6 = AF_INET6; | |
599 | break; | |
5260325f | 600 | case 'f': |
601 | config_file_name = optarg; | |
602 | break; | |
603 | case 'd': | |
bcbf86ec | 604 | if (0 == debug_flag) { |
605 | debug_flag = 1; | |
606 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
607 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
608 | options.log_level++; | |
609 | } else { | |
610 | fprintf(stderr, "Too high debugging level.\n"); | |
611 | exit(1); | |
612 | } | |
5260325f | 613 | break; |
0b6fbf03 | 614 | case 'D': |
615 | no_daemon_flag = 1; | |
616 | break; | |
5260325f | 617 | case 'i': |
618 | inetd_flag = 1; | |
619 | break; | |
620 | case 'Q': | |
9bd5b720 | 621 | /* ignored */ |
5260325f | 622 | break; |
623 | case 'q': | |
624 | options.log_level = SYSLOG_LEVEL_QUIET; | |
625 | break; | |
626 | case 'b': | |
627 | options.server_key_bits = atoi(optarg); | |
628 | break; | |
629 | case 'p': | |
48e671d5 | 630 | options.ports_from_cmdline = 1; |
bcbf86ec | 631 | if (options.num_ports >= MAX_PORTS) { |
632 | fprintf(stderr, "too many ports.\n"); | |
633 | exit(1); | |
634 | } | |
48e671d5 | 635 | options.ports[options.num_ports++] = atoi(optarg); |
5260325f | 636 | break; |
637 | case 'g': | |
638 | options.login_grace_time = atoi(optarg); | |
639 | break; | |
640 | case 'k': | |
641 | options.key_regeneration_time = atoi(optarg); | |
642 | break; | |
643 | case 'h': | |
fa08c86b | 644 | if (options.num_host_key_files >= MAX_HOSTKEYS) { |
645 | fprintf(stderr, "too many host keys.\n"); | |
646 | exit(1); | |
647 | } | |
648 | options.host_key_files[options.num_host_key_files++] = optarg; | |
5260325f | 649 | break; |
650 | case 'V': | |
651 | client_version_string = optarg; | |
652 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
653 | inetd_flag = 1; | |
654 | break; | |
c345cf9d | 655 | case 'u': |
656 | utmp_len = atoi(optarg); | |
657 | break; | |
5260325f | 658 | case '?': |
659 | default: | |
660 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
1fe6a48f | 661 | fprintf(stderr, "Usage: %s [options]\n", __progname); |
5260325f | 662 | fprintf(stderr, "Options:\n"); |
42f11eb2 | 663 | fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE); |
bcbf86ec | 664 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); |
5260325f | 665 | fprintf(stderr, " -i Started from inetd\n"); |
8abcdba4 | 666 | fprintf(stderr, " -D Do not fork into daemon mode\n"); |
5260325f | 667 | fprintf(stderr, " -q Quiet (no logging)\n"); |
668 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
669 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
9616313f | 670 | fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n"); |
5260325f | 671 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); |
672 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
42f11eb2 | 673 | _PATH_HOST_KEY_FILE); |
c345cf9d | 674 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); |
48e671d5 | 675 | fprintf(stderr, " -4 Use IPv4 only\n"); |
676 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
5260325f | 677 | exit(1); |
678 | } | |
679 | } | |
680 | ||
48e671d5 | 681 | /* |
682 | * Force logging to stderr until we have loaded the private host | |
683 | * key (unless started from inetd) | |
684 | */ | |
1fe6a48f | 685 | log_init(__progname, |
59c97189 | 686 | options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level, |
48e671d5 | 687 | options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility, |
9bd5b720 | 688 | !inetd_flag); |
48e671d5 | 689 | |
5260325f | 690 | /* Read server configuration options from the configuration file. */ |
691 | read_server_config(&options, config_file_name); | |
692 | ||
693 | /* Fill in default values for those options not explicitly set. */ | |
694 | fill_default_server_options(&options); | |
695 | ||
5260325f | 696 | /* Check that there are no remaining arguments. */ |
697 | if (optind < ac) { | |
698 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
699 | exit(1); | |
8efc0c15 | 700 | } |
5260325f | 701 | |
702 | debug("sshd version %.100s", SSH_VERSION); | |
703 | ||
fa08c86b | 704 | /* load private host keys */ |
705 | sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*)); | |
1e3b8b07 | 706 | for(i = 0; i < options.num_host_key_files; i++) |
707 | sensitive_data.host_keys[i] = NULL; | |
fa08c86b | 708 | sensitive_data.server_key = NULL; |
709 | sensitive_data.ssh1_host_key = NULL; | |
710 | sensitive_data.have_ssh1_key = 0; | |
711 | sensitive_data.have_ssh2_key = 0; | |
a306f2dd | 712 | |
fa08c86b | 713 | for(i = 0; i < options.num_host_key_files; i++) { |
714 | Key *key = load_private_key_autodetect(options.host_key_files[i]); | |
715 | if (key == NULL) { | |
a306f2dd | 716 | error("Could not load host key: %.200s: %.100s", |
fa08c86b | 717 | options.host_key_files[i], strerror(errno)); |
718 | continue; | |
a306f2dd | 719 | } |
fa08c86b | 720 | switch(key->type){ |
721 | case KEY_RSA1: | |
722 | sensitive_data.ssh1_host_key = key; | |
723 | sensitive_data.have_ssh1_key = 1; | |
724 | break; | |
725 | case KEY_RSA: | |
726 | case KEY_DSA: | |
727 | sensitive_data.have_ssh2_key = 1; | |
728 | break; | |
a306f2dd | 729 | } |
fa08c86b | 730 | sensitive_data.host_keys[i] = key; |
731 | } | |
732 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
733 | log("Disabling protocol version 1. Could not load host key"); | |
734 | options.protocol &= ~SSH_PROTO_1; | |
735 | } | |
736 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
737 | log("Disabling protocol version 2. Could not load host key"); | |
738 | options.protocol &= ~SSH_PROTO_2; | |
a306f2dd | 739 | } |
6a416424 | 740 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { |
a306f2dd | 741 | log("sshd: no hostkeys available -- exiting.\n"); |
5260325f | 742 | exit(1); |
743 | } | |
5260325f | 744 | |
a306f2dd | 745 | /* Check certain values for sanity. */ |
746 | if (options.protocol & SSH_PROTO_1) { | |
747 | if (options.server_key_bits < 512 || | |
748 | options.server_key_bits > 32768) { | |
749 | fprintf(stderr, "Bad server key size.\n"); | |
750 | exit(1); | |
751 | } | |
752 | /* | |
753 | * Check that server and host key lengths differ sufficiently. This | |
754 | * is necessary to make double encryption work with rsaref. Oh, I | |
755 | * hate software patents. I dont know if this can go? Niels | |
756 | */ | |
757 | if (options.server_key_bits > | |
fa08c86b | 758 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED && |
a306f2dd | 759 | options.server_key_bits < |
fa08c86b | 760 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { |
a306f2dd | 761 | options.server_key_bits = |
fa08c86b | 762 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED; |
a306f2dd | 763 | debug("Forcing server key to %d bits to make it differ from host key.", |
764 | options.server_key_bits); | |
765 | } | |
766 | } | |
767 | ||
77bb0bca | 768 | #ifdef HAVE_SCO_PROTECTED_PW |
769 | (void) set_auth_parameters(ac, av); | |
770 | #endif | |
771 | ||
a306f2dd | 772 | /* Initialize the log (it is reinitialized below in case we forked). */ |
5260325f | 773 | if (debug_flag && !inetd_flag) |
774 | log_stderr = 1; | |
1fe6a48f | 775 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 776 | |
a306f2dd | 777 | /* |
778 | * If not in debugging mode, and not started from inetd, disconnect | |
779 | * from the controlling terminal, and fork. The original process | |
780 | * exits. | |
781 | */ | |
0b6fbf03 | 782 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { |
8efc0c15 | 783 | #ifdef TIOCNOTTY |
5260325f | 784 | int fd; |
8efc0c15 | 785 | #endif /* TIOCNOTTY */ |
5260325f | 786 | if (daemon(0, 0) < 0) |
787 | fatal("daemon() failed: %.200s", strerror(errno)); | |
788 | ||
789 | /* Disconnect from the controlling tty. */ | |
8efc0c15 | 790 | #ifdef TIOCNOTTY |
5ca51e19 | 791 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); |
5260325f | 792 | if (fd >= 0) { |
793 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
794 | close(fd); | |
795 | } | |
8efc0c15 | 796 | #endif /* TIOCNOTTY */ |
8efc0c15 | 797 | } |
5260325f | 798 | /* Reinitialize the log (because of the fork above). */ |
1fe6a48f | 799 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 800 | |
5260325f | 801 | /* Initialize the random number generator. */ |
802 | arc4random_stir(); | |
803 | ||
804 | /* Chdir to the root directory so that the current disk can be | |
805 | unmounted if desired. */ | |
806 | chdir("/"); | |
807 | ||
5260325f | 808 | /* Start listening for a socket, unless started from inetd. */ |
809 | if (inetd_flag) { | |
810 | int s1, s2; | |
811 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ | |
812 | s2 = dup(s1); | |
813 | sock_in = dup(0); | |
814 | sock_out = dup(1); | |
4c8722d9 | 815 | startup_pipe = -1; |
a306f2dd | 816 | /* |
817 | * We intentionally do not close the descriptors 0, 1, and 2 | |
818 | * as our code for setting the descriptors won\'t work if | |
819 | * ttyfd happens to be one of those. | |
820 | */ | |
5260325f | 821 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); |
fa08c86b | 822 | if (options.protocol & SSH_PROTO_1) |
823 | generate_empheral_server_key(); | |
5260325f | 824 | } else { |
48e671d5 | 825 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
826 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
827 | continue; | |
828 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
829 | fatal("Too many listen sockets. " | |
830 | "Enlarge MAX_LISTEN_SOCKS"); | |
831 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
832 | ntop, sizeof(ntop), strport, sizeof(strport), | |
833 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
834 | error("getnameinfo failed"); | |
835 | continue; | |
836 | } | |
837 | /* Create socket for listening. */ | |
838 | listen_sock = socket(ai->ai_family, SOCK_STREAM, 0); | |
839 | if (listen_sock < 0) { | |
840 | /* kernel may not support ipv6 */ | |
841 | verbose("socket: %.100s", strerror(errno)); | |
842 | continue; | |
843 | } | |
844 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
845 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
846 | close(listen_sock); | |
847 | continue; | |
848 | } | |
849 | /* | |
850 | * Set socket options. We try to make the port | |
851 | * reusable and have it close as fast as possible | |
852 | * without waiting in unnecessary wait states on | |
853 | * close. | |
854 | */ | |
855 | setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, | |
856 | (void *) &on, sizeof(on)); | |
857 | linger.l_onoff = 1; | |
858 | linger.l_linger = 5; | |
859 | setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, | |
860 | (void *) &linger, sizeof(linger)); | |
861 | ||
862 | debug("Bind to port %s on %s.", strport, ntop); | |
863 | ||
864 | /* Bind the socket to the desired port. */ | |
32ced054 | 865 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { |
866 | if (!ai->ai_next) | |
867 | error("Bind to port %s on %s failed: %.200s.", | |
868 | strport, ntop, strerror(errno)); | |
48e671d5 | 869 | close(listen_sock); |
870 | continue; | |
871 | } | |
872 | listen_socks[num_listen_socks] = listen_sock; | |
873 | num_listen_socks++; | |
874 | ||
875 | /* Start listening on the port. */ | |
876 | log("Server listening on %s port %s.", ntop, strport); | |
877 | if (listen(listen_sock, 5) < 0) | |
878 | fatal("listen: %.100s", strerror(errno)); | |
879 | ||
5260325f | 880 | } |
48e671d5 | 881 | freeaddrinfo(options.listen_addrs); |
882 | ||
883 | if (!num_listen_socks) | |
884 | fatal("Cannot bind any address."); | |
885 | ||
5260325f | 886 | if (!debug_flag) { |
aa3378df | 887 | /* |
97fb6912 | 888 | * Record our pid in /var/run/sshd.pid to make it |
889 | * easier to kill the correct sshd. We don't want to | |
890 | * do this before the bind above because the bind will | |
aa3378df | 891 | * fail if there already is a daemon, and this will |
892 | * overwrite any old pid in the file. | |
893 | */ | |
3c62e7eb | 894 | f = fopen(options.pid_file, "wb"); |
5260325f | 895 | if (f) { |
1e3b8b07 | 896 | fprintf(f, "%u\n", (u_int) getpid()); |
5260325f | 897 | fclose(f); |
898 | } | |
8efc0c15 | 899 | } |
59c97189 | 900 | if (options.protocol & SSH_PROTO_1) |
fa08c86b | 901 | generate_empheral_server_key(); |
5260325f | 902 | |
5260325f | 903 | /* Arrange to restart on SIGHUP. The handler needs listen_sock. */ |
904 | signal(SIGHUP, sighup_handler); | |
089fbbd2 | 905 | |
5260325f | 906 | signal(SIGTERM, sigterm_handler); |
907 | signal(SIGQUIT, sigterm_handler); | |
908 | ||
909 | /* Arrange SIGCHLD to be caught. */ | |
910 | signal(SIGCHLD, main_sigchld_handler); | |
911 | ||
48e671d5 | 912 | /* setup fd set for listen */ |
089fbbd2 | 913 | fdset = NULL; |
48e671d5 | 914 | maxfd = 0; |
915 | for (i = 0; i < num_listen_socks; i++) | |
916 | if (listen_socks[i] > maxfd) | |
917 | maxfd = listen_socks[i]; | |
089fbbd2 | 918 | /* pipes connected to unauthenticated childs */ |
919 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
920 | for (i = 0; i < options.max_startups; i++) | |
921 | startup_pipes[i] = -1; | |
48e671d5 | 922 | |
aa3378df | 923 | /* |
924 | * Stay listening for connections until the system crashes or | |
925 | * the daemon is killed with a signal. | |
926 | */ | |
5260325f | 927 | for (;;) { |
928 | if (received_sighup) | |
929 | sighup_restart(); | |
089fbbd2 | 930 | if (fdset != NULL) |
931 | xfree(fdset); | |
b5c334cc | 932 | fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); |
089fbbd2 | 933 | fdset = (fd_set *)xmalloc(fdsetsz); |
48e671d5 | 934 | memset(fdset, 0, fdsetsz); |
089fbbd2 | 935 | |
48e671d5 | 936 | for (i = 0; i < num_listen_socks; i++) |
937 | FD_SET(listen_socks[i], fdset); | |
089fbbd2 | 938 | for (i = 0; i < options.max_startups; i++) |
939 | if (startup_pipes[i] != -1) | |
940 | FD_SET(startup_pipes[i], fdset); | |
941 | ||
942 | /* Wait in select until there is a connection. */ | |
59c97189 | 943 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); |
944 | if (ret < 0 && errno != EINTR) | |
945 | error("select: %.100s", strerror(errno)); | |
946 | if (key_used && key_do_regen) { | |
947 | generate_empheral_server_key(); | |
948 | key_used = 0; | |
949 | key_do_regen = 0; | |
48e671d5 | 950 | } |
59c97189 | 951 | if (ret < 0) |
952 | continue; | |
953 | ||
089fbbd2 | 954 | for (i = 0; i < options.max_startups; i++) |
955 | if (startup_pipes[i] != -1 && | |
956 | FD_ISSET(startup_pipes[i], fdset)) { | |
957 | /* | |
958 | * the read end of the pipe is ready | |
959 | * if the child has closed the pipe | |
8abcdba4 | 960 | * after successful authentication |
089fbbd2 | 961 | * or if the child has died |
962 | */ | |
963 | close(startup_pipes[i]); | |
964 | startup_pipes[i] = -1; | |
965 | startups--; | |
966 | } | |
48e671d5 | 967 | for (i = 0; i < num_listen_socks; i++) { |
968 | if (!FD_ISSET(listen_socks[i], fdset)) | |
5260325f | 969 | continue; |
089fbbd2 | 970 | fromlen = sizeof(from); |
971 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
972 | &fromlen); | |
973 | if (newsock < 0) { | |
974 | if (errno != EINTR && errno != EWOULDBLOCK) | |
975 | error("accept: %.100s", strerror(errno)); | |
976 | continue; | |
977 | } | |
978 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
979 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
980 | continue; | |
981 | } | |
c345cf9d | 982 | if (drop_connection(startups) == 1) { |
983 | debug("drop connection #%d", startups); | |
089fbbd2 | 984 | close(newsock); |
985 | continue; | |
986 | } | |
987 | if (pipe(startup_p) == -1) { | |
988 | close(newsock); | |
989 | continue; | |
990 | } | |
991 | ||
992 | for (j = 0; j < options.max_startups; j++) | |
993 | if (startup_pipes[j] == -1) { | |
994 | startup_pipes[j] = startup_p[0]; | |
995 | if (maxfd < startup_p[0]) | |
996 | maxfd = startup_p[0]; | |
997 | startups++; | |
998 | break; | |
999 | } | |
2b87da3b | 1000 | |
aa3378df | 1001 | /* |
089fbbd2 | 1002 | * Got connection. Fork a child to handle it, unless |
1003 | * we are in debugging mode. | |
aa3378df | 1004 | */ |
089fbbd2 | 1005 | if (debug_flag) { |
aa3378df | 1006 | /* |
089fbbd2 | 1007 | * In debugging mode. Close the listening |
1008 | * socket, and start processing the | |
1009 | * connection without forking. | |
aa3378df | 1010 | */ |
089fbbd2 | 1011 | debug("Server will not fork when running in debugging mode."); |
48e671d5 | 1012 | close_listen_socks(); |
5260325f | 1013 | sock_in = newsock; |
1014 | sock_out = newsock; | |
5540ea9b | 1015 | startup_pipe = -1; |
3f7a7e4a | 1016 | pid = getpid(); |
5260325f | 1017 | break; |
089fbbd2 | 1018 | } else { |
1019 | /* | |
1020 | * Normal production daemon. Fork, and have | |
1021 | * the child process the connection. The | |
1022 | * parent continues listening. | |
1023 | */ | |
1024 | if ((pid = fork()) == 0) { | |
1025 | /* | |
1026 | * Child. Close the listening and max_startup | |
1027 | * sockets. Start using the accepted socket. | |
1028 | * Reinitialize logging (since our pid has | |
1029 | * changed). We break out of the loop to handle | |
1030 | * the connection. | |
1031 | */ | |
1032 | startup_pipe = startup_p[1]; | |
1033 | for (j = 0; j < options.max_startups; j++) | |
1034 | if (startup_pipes[j] != -1) | |
1035 | close(startup_pipes[j]); | |
1036 | close_listen_socks(); | |
1037 | sock_in = newsock; | |
1038 | sock_out = newsock; | |
1fe6a48f | 1039 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
089fbbd2 | 1040 | break; |
1041 | } | |
5260325f | 1042 | } |
5260325f | 1043 | |
089fbbd2 | 1044 | /* Parent. Stay in the loop. */ |
1045 | if (pid < 0) | |
1046 | error("fork: %.100s", strerror(errno)); | |
1047 | else | |
1048 | debug("Forked child %d.", pid); | |
5260325f | 1049 | |
089fbbd2 | 1050 | close(startup_p[1]); |
5260325f | 1051 | |
089fbbd2 | 1052 | /* Mark that the key has been used (it was "given" to the child). */ |
59c97189 | 1053 | if ((options.protocol & SSH_PROTO_1) && |
1054 | key_used == 0) { | |
1055 | /* Schedule server key regeneration alarm. */ | |
1056 | signal(SIGALRM, key_regeneration_alarm); | |
1057 | alarm(options.key_regeneration_time); | |
1058 | key_used = 1; | |
1059 | } | |
5260325f | 1060 | |
089fbbd2 | 1061 | arc4random_stir(); |
1062 | ||
1063 | /* Close the new socket (the child is now taking care of it). */ | |
1064 | close(newsock); | |
1065 | } | |
48e671d5 | 1066 | /* child process check (or debug mode) */ |
1067 | if (num_listen_socks < 0) | |
1068 | break; | |
5260325f | 1069 | } |
1070 | } | |
8efc0c15 | 1071 | |
5260325f | 1072 | /* This is the child processing a new connection. */ |
1073 | ||
aa3378df | 1074 | /* |
1075 | * Disable the key regeneration alarm. We will not regenerate the | |
1076 | * key since we are no longer in a position to give it to anyone. We | |
1077 | * will not restart on SIGHUP since it no longer makes sense. | |
1078 | */ | |
5260325f | 1079 | alarm(0); |
1080 | signal(SIGALRM, SIG_DFL); | |
1081 | signal(SIGHUP, SIG_DFL); | |
1082 | signal(SIGTERM, SIG_DFL); | |
1083 | signal(SIGQUIT, SIG_DFL); | |
1084 | signal(SIGCHLD, SIG_DFL); | |
9aaf9be4 | 1085 | signal(SIGINT, SIG_DFL); |
5260325f | 1086 | |
aa3378df | 1087 | /* |
1088 | * Set socket options for the connection. We want the socket to | |
1089 | * close as fast as possible without waiting for anything. If the | |
1090 | * connection is not a socket, these will do nothing. | |
1091 | */ | |
1092 | /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 1093 | linger.l_onoff = 1; |
1094 | linger.l_linger = 5; | |
1095 | setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger)); | |
1096 | ||
b5c334cc | 1097 | /* Set keepalives if requested. */ |
1098 | if (options.keepalives && | |
1099 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on, | |
1100 | sizeof(on)) < 0) | |
1101 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1102 | ||
aa3378df | 1103 | /* |
1104 | * Register our connection. This turns encryption off because we do | |
1105 | * not have a key. | |
1106 | */ | |
5260325f | 1107 | packet_set_connection(sock_in, sock_out); |
1108 | ||
1109 | remote_port = get_remote_port(); | |
1110 | remote_ip = get_remote_ipaddr(); | |
1111 | ||
1112 | /* Check whether logins are denied from this host. */ | |
1113 | #ifdef LIBWRAP | |
48e671d5 | 1114 | /* XXX LIBWRAP noes not know about IPv6 */ |
5260325f | 1115 | { |
1116 | struct request_info req; | |
8efc0c15 | 1117 | |
1fe6a48f | 1118 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, NULL); |
5260325f | 1119 | fromhost(&req); |
8efc0c15 | 1120 | |
5260325f | 1121 | if (!hosts_access(&req)) { |
1122 | close(sock_in); | |
1123 | close(sock_out); | |
1124 | refuse(&req); | |
1125 | } | |
48e671d5 | 1126 | /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */ |
8efc0c15 | 1127 | } |
48e671d5 | 1128 | #endif /* LIBWRAP */ |
5260325f | 1129 | /* Log the connection. */ |
1130 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
8efc0c15 | 1131 | |
aa3378df | 1132 | /* |
1133 | * We don\'t want to listen forever unless the other side | |
1134 | * successfully authenticates itself. So we set up an alarm which is | |
1135 | * cleared after successful authentication. A limit of zero | |
1136 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1137 | * mode; it is just annoying to have the server exit just when you | |
1138 | * are about to discover the bug. | |
1139 | */ | |
5260325f | 1140 | signal(SIGALRM, grace_alarm_handler); |
1141 | if (!debug_flag) | |
1142 | alarm(options.login_grace_time); | |
1143 | ||
7368a6c8 | 1144 | sshd_exchange_identification(sock_in, sock_out); |
aa3378df | 1145 | /* |
6ffc9c88 | 1146 | * Check that the connection comes from a privileged port. |
1147 | * Rhosts-Authentication only makes sense from priviledged | |
aa3378df | 1148 | * programs. Of course, if the intruder has root access on his local |
1149 | * machine, he can connect from any port. So do not use these | |
1150 | * authentication methods from machines that you do not trust. | |
1151 | */ | |
5260325f | 1152 | if (remote_port >= IPPORT_RESERVED || |
1153 | remote_port < IPPORT_RESERVED / 2) { | |
6ffc9c88 | 1154 | debug("Rhosts Authentication disabled, " |
fa08c86b | 1155 | "originating port not trusted."); |
5260325f | 1156 | options.rhosts_authentication = 0; |
5260325f | 1157 | } |
48e671d5 | 1158 | #ifdef KRB4 |
1159 | if (!packet_connection_is_ipv4() && | |
1160 | options.kerberos_authentication) { | |
1161 | debug("Kerberos Authentication disabled, only available for IPv4."); | |
1162 | options.kerberos_authentication = 0; | |
1163 | } | |
1164 | #endif /* KRB4 */ | |
abf1f107 | 1165 | #ifdef AFS |
1166 | /* If machine has AFS, set process authentication group. */ | |
1167 | if (k_hasafs()) { | |
1168 | k_setpag(); | |
1169 | k_unlog(); | |
1170 | } | |
1171 | #endif /* AFS */ | |
48e671d5 | 1172 | |
5260325f | 1173 | packet_set_nonblocking(); |
1174 | ||
7b2ea3a1 | 1175 | /* perform the key exchange */ |
7b2ea3a1 | 1176 | /* authenticate user and start session */ |
e78a59f5 | 1177 | if (compat20) { |
1178 | do_ssh2_kex(); | |
1179 | do_authentication2(); | |
1180 | } else { | |
1181 | do_ssh1_kex(); | |
1182 | do_authentication(); | |
1183 | } | |
8efc0c15 | 1184 | |
1185 | #ifdef KRB4 | |
5260325f | 1186 | /* Cleanup user's ticket cache file. */ |
1187 | if (options.kerberos_ticket_cleanup) | |
1188 | (void) dest_tkt(); | |
8efc0c15 | 1189 | #endif /* KRB4 */ |
1190 | ||
5260325f | 1191 | /* The connection has been terminated. */ |
1192 | verbose("Closing connection to %.100s", remote_ip); | |
8efc0c15 | 1193 | |
d94aa2ae | 1194 | #ifdef USE_PAM |
a5c9cd31 | 1195 | finish_pam(); |
d94aa2ae | 1196 | #endif /* USE_PAM */ |
8efc0c15 | 1197 | |
5260325f | 1198 | packet_close(); |
1199 | exit(0); | |
1200 | } | |
8efc0c15 | 1201 | |
5260325f | 1202 | /* |
7b2ea3a1 | 1203 | * SSH1 key exchange |
5260325f | 1204 | */ |
e7c0f9d5 | 1205 | void |
1e3b8b07 | 1206 | do_ssh1_kex(void) |
8efc0c15 | 1207 | { |
5260325f | 1208 | int i, len; |
7b2ea3a1 | 1209 | int plen, slen; |
46aa2d1f | 1210 | int rsafail = 0; |
5260325f | 1211 | BIGNUM *session_key_int; |
1e3b8b07 | 1212 | u_char session_key[SSH_SESSION_KEY_LENGTH]; |
1213 | u_char cookie[8]; | |
1214 | u_int cipher_type, auth_mask, protocol_flags; | |
5260325f | 1215 | u_int32_t rand = 0; |
1216 | ||
aa3378df | 1217 | /* |
1218 | * Generate check bytes that the client must send back in the user | |
1219 | * packet in order for it to be accepted; this is used to defy ip | |
1220 | * spoofing attacks. Note that this only works against somebody | |
1221 | * doing IP spoofing from a remote machine; any machine on the local | |
1222 | * network can still see outgoing packets and catch the random | |
1223 | * cookie. This only affects rhosts authentication, and this is one | |
1224 | * of the reasons why it is inherently insecure. | |
1225 | */ | |
5260325f | 1226 | for (i = 0; i < 8; i++) { |
1227 | if (i % 4 == 0) | |
1228 | rand = arc4random(); | |
7b2ea3a1 | 1229 | cookie[i] = rand & 0xff; |
5260325f | 1230 | rand >>= 8; |
1231 | } | |
1232 | ||
aa3378df | 1233 | /* |
1234 | * Send our public key. We include in the packet 64 bits of random | |
1235 | * data that must be matched in the reply in order to prevent IP | |
1236 | * spoofing. | |
1237 | */ | |
5260325f | 1238 | packet_start(SSH_SMSG_PUBLIC_KEY); |
1239 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1240 | packet_put_char(cookie[i]); |
5260325f | 1241 | |
1242 | /* Store our public server RSA key. */ | |
fa08c86b | 1243 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); |
1244 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1245 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
5260325f | 1246 | |
1247 | /* Store our public host RSA key. */ | |
fa08c86b | 1248 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); |
1249 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1250 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
5260325f | 1251 | |
1252 | /* Put protocol flags. */ | |
1253 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1254 | ||
1255 | /* Declare which ciphers we support. */ | |
94ec8c6b | 1256 | packet_put_int(cipher_mask_ssh1(0)); |
5260325f | 1257 | |
1258 | /* Declare supported authentication types. */ | |
1259 | auth_mask = 0; | |
1260 | if (options.rhosts_authentication) | |
1261 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
1262 | if (options.rhosts_rsa_authentication) | |
1263 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1264 | if (options.rsa_authentication) | |
1265 | auth_mask |= 1 << SSH_AUTH_RSA; | |
8efc0c15 | 1266 | #ifdef KRB4 |
5260325f | 1267 | if (options.kerberos_authentication) |
1268 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
8efc0c15 | 1269 | #endif |
1270 | #ifdef AFS | |
5260325f | 1271 | if (options.kerberos_tgt_passing) |
1272 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
1273 | if (options.afs_token_passing) | |
1274 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
8efc0c15 | 1275 | #endif |
d464095c | 1276 | if (options.challenge_reponse_authentication == 1) |
5260325f | 1277 | auth_mask |= 1 << SSH_AUTH_TIS; |
5260325f | 1278 | if (options.password_authentication) |
1279 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1280 | packet_put_int(auth_mask); | |
1281 | ||
1282 | /* Send the packet and wait for it to be sent. */ | |
1283 | packet_send(); | |
1284 | packet_write_wait(); | |
1285 | ||
fa08c86b | 1286 | debug("Sent %d bit server key and %d bit host key.", |
1287 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1288 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
5260325f | 1289 | |
1290 | /* Read clients reply (cipher type and session key). */ | |
1291 | packet_read_expect(&plen, SSH_CMSG_SESSION_KEY); | |
1292 | ||
2d86a6cc | 1293 | /* Get cipher type and check whether we accept this. */ |
5260325f | 1294 | cipher_type = packet_get_char(); |
1295 | ||
94ec8c6b | 1296 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) |
2d86a6cc | 1297 | packet_disconnect("Warning: client selects unsupported cipher."); |
1298 | ||
5260325f | 1299 | /* Get check bytes from the packet. These must match those we |
1300 | sent earlier with the public key packet. */ | |
1301 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1302 | if (cookie[i] != packet_get_char()) |
5260325f | 1303 | packet_disconnect("IP Spoofing check bytes do not match."); |
1304 | ||
1305 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1306 | ||
1307 | /* Get the encrypted integer. */ | |
1308 | session_key_int = BN_new(); | |
1309 | packet_get_bignum(session_key_int, &slen); | |
1310 | ||
5260325f | 1311 | protocol_flags = packet_get_int(); |
1312 | packet_set_protocol_flags(protocol_flags); | |
1313 | ||
1314 | packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY); | |
1315 | ||
aa3378df | 1316 | /* |
1317 | * Decrypt it using our private server key and private host key (key | |
1318 | * with larger modulus first). | |
1319 | */ | |
fa08c86b | 1320 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { |
46aa2d1f | 1321 | /* Server key has bigger modulus. */ |
fa08c86b | 1322 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < |
1323 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1324 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1325 | get_remote_ipaddr(), | |
1326 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1327 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1328 | SSH_KEY_BITS_RESERVED); | |
5260325f | 1329 | } |
46aa2d1f | 1330 | if (rsa_private_decrypt(session_key_int, session_key_int, |
1331 | sensitive_data.server_key->rsa) <= 0) | |
1332 | rsafail++; | |
1333 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1334 | sensitive_data.ssh1_host_key->rsa) <= 0) | |
1335 | rsafail++; | |
5260325f | 1336 | } else { |
1337 | /* Host key has bigger modulus (or they are equal). */ | |
fa08c86b | 1338 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < |
1339 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1340 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1341 | get_remote_ipaddr(), | |
1342 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1343 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1344 | SSH_KEY_BITS_RESERVED); | |
5260325f | 1345 | } |
46aa2d1f | 1346 | if (rsa_private_decrypt(session_key_int, session_key_int, |
1347 | sensitive_data.ssh1_host_key->rsa) < 0) | |
1348 | rsafail++; | |
1349 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1350 | sensitive_data.server_key->rsa) < 0) | |
1351 | rsafail++; | |
5260325f | 1352 | } |
aa3378df | 1353 | /* |
1354 | * Extract session key from the decrypted integer. The key is in the | |
1355 | * least significant 256 bits of the integer; the first byte of the | |
1356 | * key is in the highest bits. | |
1357 | */ | |
46aa2d1f | 1358 | if (!rsafail) { |
1359 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
1360 | len = BN_num_bytes(session_key_int); | |
1361 | if (len < 0 || len > sizeof(session_key)) { | |
1362 | error("do_connection: bad session key len from %s: " | |
5ca51e19 | 1363 | "session_key_int %d > sizeof(session_key) %lu", |
1364 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); | |
46aa2d1f | 1365 | rsafail++; |
1366 | } else { | |
1367 | memset(session_key, 0, sizeof(session_key)); | |
1368 | BN_bn2bin(session_key_int, | |
1369 | session_key + sizeof(session_key) - len); | |
00be5382 | 1370 | |
1371 | compute_session_id(session_id, cookie, | |
1372 | sensitive_data.ssh1_host_key->rsa->n, | |
1373 | sensitive_data.server_key->rsa->n); | |
1374 | /* | |
1375 | * Xor the first 16 bytes of the session key with the | |
1376 | * session id. | |
1377 | */ | |
1378 | for (i = 0; i < 16; i++) | |
1379 | session_key[i] ^= session_id[i]; | |
46aa2d1f | 1380 | } |
1381 | } | |
1382 | if (rsafail) { | |
00be5382 | 1383 | int bytes = BN_num_bytes(session_key_int); |
1384 | char *buf = xmalloc(bytes); | |
1385 | MD5_CTX md; | |
1386 | ||
46aa2d1f | 1387 | log("do_connection: generating a fake encryption key"); |
00be5382 | 1388 | BN_bn2bin(session_key_int, buf); |
1389 | MD5_Init(&md); | |
1390 | MD5_Update(&md, buf, bytes); | |
1391 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1392 | MD5_Final(session_key, &md); | |
1393 | MD5_Init(&md); | |
1394 | MD5_Update(&md, session_key, 16); | |
1395 | MD5_Update(&md, buf, bytes); | |
1396 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1397 | MD5_Final(session_key + 16, &md); | |
1398 | memset(buf, 0, bytes); | |
1399 | xfree(buf); | |
0572fe75 | 1400 | for (i = 0; i < 16; i++) |
1401 | session_id[i] = session_key[i] ^ session_key[i + 16]; | |
46aa2d1f | 1402 | } |
00be5382 | 1403 | /* Destroy the private and public keys. They will no longer be needed. */ |
1404 | destroy_sensitive_data(); | |
1405 | ||
7b2ea3a1 | 1406 | /* Destroy the decrypted integer. It is no longer needed. */ |
1407 | BN_clear_free(session_key_int); | |
1408 | ||
5260325f | 1409 | /* Set the session key. From this on all communications will be encrypted. */ |
1410 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1411 | ||
1412 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1413 | memset(session_key, 0, sizeof(session_key)); | |
1414 | ||
1415 | debug("Received session key; encryption turned on."); | |
1416 | ||
1417 | /* Send an acknowledgement packet. Note that this packet is sent encrypted. */ | |
1418 | packet_start(SSH_SMSG_SUCCESS); | |
1419 | packet_send(); | |
1420 | packet_write_wait(); | |
5260325f | 1421 | } |
e78a59f5 | 1422 | |
1423 | /* | |
1424 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1425 | */ | |
1426 | void | |
1e3b8b07 | 1427 | do_ssh2_kex(void) |
e78a59f5 | 1428 | { |
1429 | Buffer *server_kexinit; | |
1430 | Buffer *client_kexinit; | |
94ec8c6b | 1431 | int payload_len; |
e78a59f5 | 1432 | int i; |
e78a59f5 | 1433 | Kex *kex; |
e78a59f5 | 1434 | char *cprop[PROPOSAL_MAX]; |
e78a59f5 | 1435 | |
1436 | /* KEXINIT */ | |
1437 | ||
a8be9f80 | 1438 | if (options.ciphers != NULL) { |
6ae2364d | 1439 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
a8be9f80 | 1440 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
1441 | } | |
b2552997 | 1442 | if (options.macs != NULL) { |
1443 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
1444 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
1445 | } | |
fa08c86b | 1446 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
1447 | ||
71276795 | 1448 | server_kexinit = kex_init(myproposal); |
e78a59f5 | 1449 | client_kexinit = xmalloc(sizeof(*client_kexinit)); |
1450 | buffer_init(client_kexinit); | |
e78a59f5 | 1451 | |
71276795 | 1452 | /* algorithm negotiation */ |
1453 | kex_exchange_kexinit(server_kexinit, client_kexinit, cprop); | |
1454 | kex = kex_choose_conf(cprop, myproposal, 1); | |
1455 | for (i = 0; i < PROPOSAL_MAX; i++) | |
1456 | xfree(cprop[i]); | |
e78a59f5 | 1457 | |
94ec8c6b | 1458 | switch (kex->kex_type) { |
1459 | case DH_GRP1_SHA1: | |
1460 | ssh_dh1_server(kex, client_kexinit, server_kexinit); | |
1461 | break; | |
1462 | case DH_GEX_SHA1: | |
1463 | ssh_dhgex_server(kex, client_kexinit, server_kexinit); | |
1464 | break; | |
1465 | default: | |
1466 | fatal("Unsupported key exchange %d", kex->kex_type); | |
1467 | } | |
1468 | ||
1469 | debug("send SSH2_MSG_NEWKEYS."); | |
1470 | packet_start(SSH2_MSG_NEWKEYS); | |
1471 | packet_send(); | |
1472 | packet_write_wait(); | |
1473 | debug("done: send SSH2_MSG_NEWKEYS."); | |
1474 | ||
1475 | debug("Wait SSH2_MSG_NEWKEYS."); | |
1476 | packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS); | |
1477 | debug("GOT SSH2_MSG_NEWKEYS."); | |
1478 | ||
1479 | #ifdef DEBUG_KEXDH | |
1480 | /* send 1st encrypted/maced/compressed message */ | |
1481 | packet_start(SSH2_MSG_IGNORE); | |
1482 | packet_put_cstring("markus"); | |
1483 | packet_send(); | |
1484 | packet_write_wait(); | |
1485 | #endif | |
1486 | ||
1487 | debug("done: KEX2."); | |
1488 | } | |
1489 | ||
1490 | /* | |
1491 | * SSH2 key exchange | |
1492 | */ | |
1493 | ||
1494 | /* diffie-hellman-group1-sha1 */ | |
1495 | ||
1496 | void | |
1497 | ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit) | |
1498 | { | |
1499 | #ifdef DEBUG_KEXDH | |
1500 | int i; | |
1501 | #endif | |
1502 | int payload_len, dlen; | |
1503 | int slen; | |
1e3b8b07 | 1504 | u_char *signature = NULL; |
1505 | u_char *server_host_key_blob = NULL; | |
1506 | u_int sbloblen; | |
1507 | u_int klen, kout; | |
1508 | u_char *kbuf; | |
1509 | u_char *hash; | |
94ec8c6b | 1510 | BIGNUM *shared_secret = 0; |
1511 | DH *dh; | |
1512 | BIGNUM *dh_client_pub = 0; | |
fa08c86b | 1513 | Key *hostkey; |
1514 | ||
1515 | hostkey = get_hostkey_by_type(kex->hostkey_type); | |
1516 | if (hostkey == NULL) | |
1517 | fatal("Unsupported hostkey type %d", kex->hostkey_type); | |
e78a59f5 | 1518 | |
94ec8c6b | 1519 | /* KEXDH */ |
3e1caa83 | 1520 | /* generate DH key */ |
1521 | dh = dh_new_group1(); /* XXX depends on 'kex' */ | |
1522 | dh_gen_key(dh); | |
1523 | ||
e78a59f5 | 1524 | debug("Wait SSH2_MSG_KEXDH_INIT."); |
1525 | packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT); | |
1526 | ||
1527 | /* key, cert */ | |
1528 | dh_client_pub = BN_new(); | |
1529 | if (dh_client_pub == NULL) | |
1530 | fatal("dh_client_pub == NULL"); | |
1531 | packet_get_bignum2(dh_client_pub, &dlen); | |
1532 | ||
1533 | #ifdef DEBUG_KEXDH | |
1534 | fprintf(stderr, "\ndh_client_pub= "); | |
188adeb2 | 1535 | BN_print_fp(stderr, dh_client_pub); |
e78a59f5 | 1536 | fprintf(stderr, "\n"); |
1537 | debug("bits %d", BN_num_bits(dh_client_pub)); | |
1538 | #endif | |
1539 | ||
e78a59f5 | 1540 | #ifdef DEBUG_KEXDH |
1541 | fprintf(stderr, "\np= "); | |
188adeb2 | 1542 | BN_print_fp(stderr, dh->p); |
e78a59f5 | 1543 | fprintf(stderr, "\ng= "); |
188adeb2 | 1544 | bn_print(dh->g); |
e78a59f5 | 1545 | fprintf(stderr, "\npub= "); |
188adeb2 | 1546 | BN_print_fp(stderr, dh->pub_key); |
e78a59f5 | 1547 | fprintf(stderr, "\n"); |
2b87da3b | 1548 | DHparams_print_fp(stderr, dh); |
e78a59f5 | 1549 | #endif |
a8be9f80 | 1550 | if (!dh_pub_is_valid(dh, dh_client_pub)) |
1551 | packet_disconnect("bad client public DH value"); | |
e78a59f5 | 1552 | |
1553 | klen = DH_size(dh); | |
1554 | kbuf = xmalloc(klen); | |
1555 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | |
1556 | ||
1557 | #ifdef DEBUG_KEXDH | |
1558 | debug("shared secret: len %d/%d", klen, kout); | |
1559 | fprintf(stderr, "shared secret == "); | |
1560 | for (i = 0; i< kout; i++) | |
1561 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
1562 | fprintf(stderr, "\n"); | |
1563 | #endif | |
1564 | shared_secret = BN_new(); | |
1565 | ||
1566 | BN_bin2bn(kbuf, kout, shared_secret); | |
1567 | memset(kbuf, 0, klen); | |
1568 | xfree(kbuf); | |
1569 | ||
a306f2dd | 1570 | /* XXX precompute? */ |
fa08c86b | 1571 | key_to_blob(hostkey, &server_host_key_blob, &sbloblen); |
e78a59f5 | 1572 | |
1573 | /* calc H */ /* XXX depends on 'kex' */ | |
1574 | hash = kex_hash( | |
1575 | client_version_string, | |
1576 | server_version_string, | |
1577 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
1578 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
1579 | (char *)server_host_key_blob, sbloblen, | |
1580 | dh_client_pub, | |
1581 | dh->pub_key, | |
1582 | shared_secret | |
1583 | ); | |
1584 | buffer_free(client_kexinit); | |
1585 | buffer_free(server_kexinit); | |
1586 | xfree(client_kexinit); | |
1587 | xfree(server_kexinit); | |
53a24016 | 1588 | BN_free(dh_client_pub); |
e78a59f5 | 1589 | #ifdef DEBUG_KEXDH |
6ae2364d | 1590 | fprintf(stderr, "hash == "); |
1591 | for (i = 0; i< 20; i++) | |
1592 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
1593 | fprintf(stderr, "\n"); | |
e78a59f5 | 1594 | #endif |
a306f2dd | 1595 | /* save session id := H */ |
1596 | /* XXX hashlen depends on KEX */ | |
1597 | session_id2_len = 20; | |
1598 | session_id2 = xmalloc(session_id2_len); | |
1599 | memcpy(session_id2, hash, session_id2_len); | |
1600 | ||
e78a59f5 | 1601 | /* sign H */ |
a306f2dd | 1602 | /* XXX hashlen depends on KEX */ |
fa08c86b | 1603 | key_sign(hostkey, &signature, &slen, hash, 20); |
a306f2dd | 1604 | |
1605 | destroy_sensitive_data(); | |
e78a59f5 | 1606 | |
1607 | /* send server hostkey, DH pubkey 'f' and singed H */ | |
1608 | packet_start(SSH2_MSG_KEXDH_REPLY); | |
1609 | packet_put_string((char *)server_host_key_blob, sbloblen); | |
1d1ffb87 | 1610 | packet_put_bignum2(dh->pub_key); /* f */ |
e78a59f5 | 1611 | packet_put_string((char *)signature, slen); |
1612 | packet_send(); | |
d6f24e45 | 1613 | xfree(signature); |
a306f2dd | 1614 | xfree(server_host_key_blob); |
e78a59f5 | 1615 | packet_write_wait(); |
1616 | ||
1617 | kex_derive_keys(kex, hash, shared_secret); | |
53a24016 | 1618 | BN_clear_free(shared_secret); |
e78a59f5 | 1619 | packet_set_kex(kex); |
1620 | ||
1621 | /* have keys, free DH */ | |
1622 | DH_free(dh); | |
94ec8c6b | 1623 | } |
e78a59f5 | 1624 | |
94ec8c6b | 1625 | /* diffie-hellman-group-exchange-sha1 */ |
1626 | ||
1627 | void | |
1628 | ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit) | |
1629 | { | |
1630 | #ifdef DEBUG_KEXDH | |
1631 | int i; | |
1632 | #endif | |
1633 | int payload_len, dlen; | |
1634 | int slen, nbits; | |
1e3b8b07 | 1635 | u_char *signature = NULL; |
1636 | u_char *server_host_key_blob = NULL; | |
1637 | u_int sbloblen; | |
1638 | u_int klen, kout; | |
1639 | u_char *kbuf; | |
1640 | u_char *hash; | |
94ec8c6b | 1641 | BIGNUM *shared_secret = 0; |
1642 | DH *dh; | |
1643 | BIGNUM *dh_client_pub = 0; | |
fa08c86b | 1644 | Key *hostkey; |
1645 | ||
1646 | hostkey = get_hostkey_by_type(kex->hostkey_type); | |
1647 | if (hostkey == NULL) | |
1648 | fatal("Unsupported hostkey type %d", kex->hostkey_type); | |
94ec8c6b | 1649 | |
1650 | /* KEXDHGEX */ | |
1651 | debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST."); | |
1652 | packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_REQUEST); | |
1653 | nbits = packet_get_int(); | |
1654 | dh = choose_dh(nbits); | |
1655 | ||
1656 | debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP."); | |
1657 | packet_start(SSH2_MSG_KEX_DH_GEX_GROUP); | |
1658 | packet_put_bignum2(dh->p); | |
1659 | packet_put_bignum2(dh->g); | |
e78a59f5 | 1660 | packet_send(); |
1661 | packet_write_wait(); | |
e78a59f5 | 1662 | |
3e1caa83 | 1663 | /* Compute our exchange value in parallel with the client */ |
1664 | ||
1665 | dh_gen_key(dh); | |
1666 | ||
94ec8c6b | 1667 | debug("Wait SSH2_MSG_KEX_DH_GEX_INIT."); |
1668 | packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_INIT); | |
1669 | ||
1670 | /* key, cert */ | |
1671 | dh_client_pub = BN_new(); | |
1672 | if (dh_client_pub == NULL) | |
1673 | fatal("dh_client_pub == NULL"); | |
1674 | packet_get_bignum2(dh_client_pub, &dlen); | |
e78a59f5 | 1675 | |
a8be9f80 | 1676 | #ifdef DEBUG_KEXDH |
94ec8c6b | 1677 | fprintf(stderr, "\ndh_client_pub= "); |
1678 | BN_print_fp(stderr, dh_client_pub); | |
1679 | fprintf(stderr, "\n"); | |
1680 | debug("bits %d", BN_num_bits(dh_client_pub)); | |
1681 | #endif | |
1682 | ||
1683 | #ifdef DEBUG_KEXDH | |
1684 | fprintf(stderr, "\np= "); | |
1685 | BN_print_fp(stderr, dh->p); | |
1686 | fprintf(stderr, "\ng= "); | |
1687 | bn_print(dh->g); | |
1688 | fprintf(stderr, "\npub= "); | |
1689 | BN_print_fp(stderr, dh->pub_key); | |
1690 | fprintf(stderr, "\n"); | |
2b87da3b | 1691 | DHparams_print_fp(stderr, dh); |
94ec8c6b | 1692 | #endif |
1693 | if (!dh_pub_is_valid(dh, dh_client_pub)) | |
1694 | packet_disconnect("bad client public DH value"); | |
1695 | ||
1696 | klen = DH_size(dh); | |
1697 | kbuf = xmalloc(klen); | |
1698 | kout = DH_compute_key(kbuf, dh_client_pub, dh); | |
1699 | ||
1700 | #ifdef DEBUG_KEXDH | |
1701 | debug("shared secret: len %d/%d", klen, kout); | |
1702 | fprintf(stderr, "shared secret == "); | |
1703 | for (i = 0; i< kout; i++) | |
1704 | fprintf(stderr, "%02x", (kbuf[i])&0xff); | |
1705 | fprintf(stderr, "\n"); | |
1706 | #endif | |
1707 | shared_secret = BN_new(); | |
1708 | ||
1709 | BN_bin2bn(kbuf, kout, shared_secret); | |
1710 | memset(kbuf, 0, klen); | |
1711 | xfree(kbuf); | |
1712 | ||
1713 | /* XXX precompute? */ | |
fa08c86b | 1714 | key_to_blob(hostkey, &server_host_key_blob, &sbloblen); |
94ec8c6b | 1715 | |
1716 | /* calc H */ /* XXX depends on 'kex' */ | |
1717 | hash = kex_hash_gex( | |
1718 | client_version_string, | |
1719 | server_version_string, | |
1720 | buffer_ptr(client_kexinit), buffer_len(client_kexinit), | |
1721 | buffer_ptr(server_kexinit), buffer_len(server_kexinit), | |
1722 | (char *)server_host_key_blob, sbloblen, | |
1723 | nbits, dh->p, dh->g, | |
1724 | dh_client_pub, | |
1725 | dh->pub_key, | |
1726 | shared_secret | |
1727 | ); | |
1728 | buffer_free(client_kexinit); | |
1729 | buffer_free(server_kexinit); | |
1730 | xfree(client_kexinit); | |
1731 | xfree(server_kexinit); | |
53a24016 | 1732 | BN_free(dh_client_pub); |
94ec8c6b | 1733 | #ifdef DEBUG_KEXDH |
1734 | fprintf(stderr, "hash == "); | |
1735 | for (i = 0; i< 20; i++) | |
1736 | fprintf(stderr, "%02x", (hash[i])&0xff); | |
1737 | fprintf(stderr, "\n"); | |
1738 | #endif | |
1739 | /* save session id := H */ | |
1740 | /* XXX hashlen depends on KEX */ | |
1741 | session_id2_len = 20; | |
1742 | session_id2 = xmalloc(session_id2_len); | |
1743 | memcpy(session_id2, hash, session_id2_len); | |
1744 | ||
1745 | /* sign H */ | |
1746 | /* XXX hashlen depends on KEX */ | |
fa08c86b | 1747 | key_sign(hostkey, &signature, &slen, hash, 20); |
94ec8c6b | 1748 | |
1749 | destroy_sensitive_data(); | |
1750 | ||
1751 | /* send server hostkey, DH pubkey 'f' and singed H */ | |
1752 | packet_start(SSH2_MSG_KEX_DH_GEX_REPLY); | |
1753 | packet_put_string((char *)server_host_key_blob, sbloblen); | |
1754 | packet_put_bignum2(dh->pub_key); /* f */ | |
1755 | packet_put_string((char *)signature, slen); | |
e78a59f5 | 1756 | packet_send(); |
94ec8c6b | 1757 | xfree(signature); |
1758 | xfree(server_host_key_blob); | |
e78a59f5 | 1759 | packet_write_wait(); |
94ec8c6b | 1760 | |
1761 | kex_derive_keys(kex, hash, shared_secret); | |
53a24016 | 1762 | BN_clear_free(shared_secret); |
94ec8c6b | 1763 | packet_set_kex(kex); |
1764 | ||
1765 | /* have keys, free DH */ | |
1766 | DH_free(dh); | |
e78a59f5 | 1767 | } |