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1 | /* | |
2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * This program is the ssh daemon. It listens for connections from clients, | |
6 | * and performs authentication, executes use commands or shell, and forwards | |
7 | * information to/from the application to the user client over an encrypted | |
8 | * connection. This can also handle forwarding of X11, TCP/IP, and | |
9 | * authentication agent connections. | |
10 | * | |
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 | * Privilege Separation: | |
19 | * | |
20 | * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. | |
21 | * Copyright (c) 2002 Niels Provos. All rights reserved. | |
22 | * | |
23 | * Redistribution and use in source and binary forms, with or without | |
24 | * modification, are permitted provided that the following conditions | |
25 | * are met: | |
26 | * 1. Redistributions of source code must retain the above copyright | |
27 | * notice, this list of conditions and the following disclaimer. | |
28 | * 2. Redistributions in binary form must reproduce the above copyright | |
29 | * notice, this list of conditions and the following disclaimer in the | |
30 | * documentation and/or other materials provided with the distribution. | |
31 | * | |
32 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
33 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
34 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
35 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
36 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
37 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
38 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
39 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
40 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
41 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
42 | */ | |
43 | ||
44 | #include "includes.h" | |
45 | RCSID("$OpenBSD: sshd.c,v 1.260 2002/09/27 10:42:09 mickey Exp $"); | |
46 | ||
47 | #include <openssl/dh.h> | |
48 | #include <openssl/bn.h> | |
49 | #include <openssl/md5.h> | |
50 | #include <openssl/rand.h> | |
51 | #ifdef HAVE_SECUREWARE | |
52 | #include <sys/security.h> | |
53 | #include <prot.h> | |
54 | #endif | |
55 | ||
56 | #include "ssh.h" | |
57 | #include "ssh1.h" | |
58 | #include "ssh2.h" | |
59 | #include "xmalloc.h" | |
60 | #include "rsa.h" | |
61 | #include "sshpty.h" | |
62 | #include "packet.h" | |
63 | #include "mpaux.h" | |
64 | #include "log.h" | |
65 | #include "servconf.h" | |
66 | #include "uidswap.h" | |
67 | #include "compat.h" | |
68 | #include "buffer.h" | |
69 | #include "cipher.h" | |
70 | #include "kex.h" | |
71 | #include "key.h" | |
72 | #include "dh.h" | |
73 | #include "myproposal.h" | |
74 | #include "authfile.h" | |
75 | #include "pathnames.h" | |
76 | #include "atomicio.h" | |
77 | #include "canohost.h" | |
78 | #include "auth.h" | |
79 | #include "misc.h" | |
80 | #include "dispatch.h" | |
81 | #include "channels.h" | |
82 | #include "session.h" | |
83 | #include "monitor_mm.h" | |
84 | #include "monitor.h" | |
85 | #include "monitor_wrap.h" | |
86 | #include "monitor_fdpass.h" | |
87 | ||
88 | #ifdef LIBWRAP | |
89 | #include <tcpd.h> | |
90 | #include <syslog.h> | |
91 | int allow_severity = LOG_INFO; | |
92 | int deny_severity = LOG_WARNING; | |
93 | #endif /* LIBWRAP */ | |
94 | ||
95 | #ifndef O_NOCTTY | |
96 | #define O_NOCTTY 0 | |
97 | #endif | |
98 | ||
99 | #ifdef HAVE___PROGNAME | |
100 | extern char *__progname; | |
101 | #else | |
102 | char *__progname; | |
103 | #endif | |
104 | ||
105 | /* Server configuration options. */ | |
106 | ServerOptions options; | |
107 | ||
108 | /* Name of the server configuration file. */ | |
109 | char *config_file_name = _PATH_SERVER_CONFIG_FILE; | |
110 | ||
111 | /* | |
112 | * Flag indicating whether IPv4 or IPv6. This can be set on the command line. | |
113 | * Default value is AF_UNSPEC means both IPv4 and IPv6. | |
114 | */ | |
115 | #ifdef IPV4_DEFAULT | |
116 | int IPv4or6 = AF_INET; | |
117 | #else | |
118 | int IPv4or6 = AF_UNSPEC; | |
119 | #endif | |
120 | ||
121 | /* | |
122 | * Debug mode flag. This can be set on the command line. If debug | |
123 | * mode is enabled, extra debugging output will be sent to the system | |
124 | * log, the daemon will not go to background, and will exit after processing | |
125 | * the first connection. | |
126 | */ | |
127 | int debug_flag = 0; | |
128 | ||
129 | /* Flag indicating that the daemon should only test the configuration and keys. */ | |
130 | int test_flag = 0; | |
131 | ||
132 | /* Flag indicating that the daemon is being started from inetd. */ | |
133 | int inetd_flag = 0; | |
134 | ||
135 | /* Flag indicating that sshd should not detach and become a daemon. */ | |
136 | int no_daemon_flag = 0; | |
137 | ||
138 | /* debug goes to stderr unless inetd_flag is set */ | |
139 | int log_stderr = 0; | |
140 | ||
141 | /* Saved arguments to main(). */ | |
142 | char **saved_argv; | |
143 | int saved_argc; | |
144 | ||
145 | /* | |
146 | * The sockets that the server is listening; this is used in the SIGHUP | |
147 | * signal handler. | |
148 | */ | |
149 | #define MAX_LISTEN_SOCKS 16 | |
150 | int listen_socks[MAX_LISTEN_SOCKS]; | |
151 | int num_listen_socks = 0; | |
152 | ||
153 | /* | |
154 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
155 | * sshd will skip the version-number exchange | |
156 | */ | |
157 | char *client_version_string = NULL; | |
158 | char *server_version_string = NULL; | |
159 | ||
160 | /* for rekeying XXX fixme */ | |
161 | Kex *xxx_kex; | |
162 | ||
163 | /* | |
164 | * Any really sensitive data in the application is contained in this | |
165 | * structure. The idea is that this structure could be locked into memory so | |
166 | * that the pages do not get written into swap. However, there are some | |
167 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
168 | * have access to the internals of them, and locking just the structure is | |
169 | * not very useful. Currently, memory locking is not implemented. | |
170 | */ | |
171 | struct { | |
172 | Key *server_key; /* ephemeral server key */ | |
173 | Key *ssh1_host_key; /* ssh1 host key */ | |
174 | Key **host_keys; /* all private host keys */ | |
175 | int have_ssh1_key; | |
176 | int have_ssh2_key; | |
177 | u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; | |
178 | } sensitive_data; | |
179 | ||
180 | /* | |
181 | * Flag indicating whether the RSA server key needs to be regenerated. | |
182 | * Is set in the SIGALRM handler and cleared when the key is regenerated. | |
183 | */ | |
184 | static volatile sig_atomic_t key_do_regen = 0; | |
185 | ||
186 | /* This is set to true when a signal is received. */ | |
187 | static volatile sig_atomic_t received_sighup = 0; | |
188 | static volatile sig_atomic_t received_sigterm = 0; | |
189 | ||
190 | /* session identifier, used by RSA-auth */ | |
191 | u_char session_id[16]; | |
192 | ||
193 | /* same for ssh2 */ | |
194 | u_char *session_id2 = NULL; | |
195 | int session_id2_len = 0; | |
196 | ||
197 | /* record remote hostname or ip */ | |
198 | u_int utmp_len = MAXHOSTNAMELEN; | |
199 | ||
200 | /* options.max_startup sized array of fd ints */ | |
201 | int *startup_pipes = NULL; | |
202 | int startup_pipe; /* in child */ | |
203 | ||
204 | /* variables used for privilege separation */ | |
205 | extern struct monitor *pmonitor; | |
206 | extern int use_privsep; | |
207 | ||
208 | /* Prototypes for various functions defined later in this file. */ | |
209 | void destroy_sensitive_data(void); | |
210 | void demote_sensitive_data(void); | |
211 | ||
212 | static void do_ssh1_kex(void); | |
213 | static void do_ssh2_kex(void); | |
214 | ||
215 | /* | |
216 | * Close all listening sockets | |
217 | */ | |
218 | static void | |
219 | close_listen_socks(void) | |
220 | { | |
221 | int i; | |
222 | ||
223 | for (i = 0; i < num_listen_socks; i++) | |
224 | close(listen_socks[i]); | |
225 | num_listen_socks = -1; | |
226 | } | |
227 | ||
228 | static void | |
229 | close_startup_pipes(void) | |
230 | { | |
231 | int i; | |
232 | ||
233 | if (startup_pipes) | |
234 | for (i = 0; i < options.max_startups; i++) | |
235 | if (startup_pipes[i] != -1) | |
236 | close(startup_pipes[i]); | |
237 | } | |
238 | ||
239 | /* | |
240 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
241 | * the effect is to reread the configuration file (and to regenerate | |
242 | * the server key). | |
243 | */ | |
244 | static void | |
245 | sighup_handler(int sig) | |
246 | { | |
247 | int save_errno = errno; | |
248 | ||
249 | received_sighup = 1; | |
250 | signal(SIGHUP, sighup_handler); | |
251 | errno = save_errno; | |
252 | } | |
253 | ||
254 | /* | |
255 | * Called from the main program after receiving SIGHUP. | |
256 | * Restarts the server. | |
257 | */ | |
258 | static void | |
259 | sighup_restart(void) | |
260 | { | |
261 | log("Received SIGHUP; restarting."); | |
262 | close_listen_socks(); | |
263 | close_startup_pipes(); | |
264 | execv(saved_argv[0], saved_argv); | |
265 | log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], | |
266 | strerror(errno)); | |
267 | exit(1); | |
268 | } | |
269 | ||
270 | /* | |
271 | * Generic signal handler for terminating signals in the master daemon. | |
272 | */ | |
273 | static void | |
274 | sigterm_handler(int sig) | |
275 | { | |
276 | received_sigterm = sig; | |
277 | } | |
278 | ||
279 | /* | |
280 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
281 | * reap any zombies left by exited children. | |
282 | */ | |
283 | static void | |
284 | main_sigchld_handler(int sig) | |
285 | { | |
286 | int save_errno = errno; | |
287 | pid_t pid; | |
288 | int status; | |
289 | ||
290 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || | |
291 | (pid < 0 && errno == EINTR)) | |
292 | ; | |
293 | ||
294 | signal(SIGCHLD, main_sigchld_handler); | |
295 | errno = save_errno; | |
296 | } | |
297 | ||
298 | /* | |
299 | * Signal handler for the alarm after the login grace period has expired. | |
300 | */ | |
301 | static void | |
302 | grace_alarm_handler(int sig) | |
303 | { | |
304 | /* XXX no idea how fix this signal handler */ | |
305 | ||
306 | /* Log error and exit. */ | |
307 | fatal("Timeout before authentication for %s", get_remote_ipaddr()); | |
308 | } | |
309 | ||
310 | /* | |
311 | * Signal handler for the key regeneration alarm. Note that this | |
312 | * alarm only occurs in the daemon waiting for connections, and it does not | |
313 | * do anything with the private key or random state before forking. | |
314 | * Thus there should be no concurrency control/asynchronous execution | |
315 | * problems. | |
316 | */ | |
317 | static void | |
318 | generate_ephemeral_server_key(void) | |
319 | { | |
320 | u_int32_t rnd = 0; | |
321 | int i; | |
322 | ||
323 | verbose("Generating %s%d bit RSA key.", | |
324 | sensitive_data.server_key ? "new " : "", options.server_key_bits); | |
325 | if (sensitive_data.server_key != NULL) | |
326 | key_free(sensitive_data.server_key); | |
327 | sensitive_data.server_key = key_generate(KEY_RSA1, | |
328 | options.server_key_bits); | |
329 | verbose("RSA key generation complete."); | |
330 | ||
331 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
332 | if (i % 4 == 0) | |
333 | rnd = arc4random(); | |
334 | sensitive_data.ssh1_cookie[i] = rnd & 0xff; | |
335 | rnd >>= 8; | |
336 | } | |
337 | arc4random_stir(); | |
338 | } | |
339 | ||
340 | static void | |
341 | key_regeneration_alarm(int sig) | |
342 | { | |
343 | int save_errno = errno; | |
344 | ||
345 | signal(SIGALRM, SIG_DFL); | |
346 | errno = save_errno; | |
347 | key_do_regen = 1; | |
348 | } | |
349 | ||
350 | static void | |
351 | sshd_exchange_identification(int sock_in, int sock_out) | |
352 | { | |
353 | int i, mismatch; | |
354 | int remote_major, remote_minor; | |
355 | int major, minor; | |
356 | char *s; | |
357 | char buf[256]; /* Must not be larger than remote_version. */ | |
358 | char remote_version[256]; /* Must be at least as big as buf. */ | |
359 | ||
360 | if ((options.protocol & SSH_PROTO_1) && | |
361 | (options.protocol & SSH_PROTO_2)) { | |
362 | major = PROTOCOL_MAJOR_1; | |
363 | minor = 99; | |
364 | } else if (options.protocol & SSH_PROTO_2) { | |
365 | major = PROTOCOL_MAJOR_2; | |
366 | minor = PROTOCOL_MINOR_2; | |
367 | } else { | |
368 | major = PROTOCOL_MAJOR_1; | |
369 | minor = PROTOCOL_MINOR_1; | |
370 | } | |
371 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
372 | server_version_string = xstrdup(buf); | |
373 | ||
374 | if (client_version_string == NULL) { | |
375 | /* Send our protocol version identification. */ | |
376 | if (atomicio(write, sock_out, server_version_string, | |
377 | strlen(server_version_string)) | |
378 | != strlen(server_version_string)) { | |
379 | log("Could not write ident string to %s", get_remote_ipaddr()); | |
380 | fatal_cleanup(); | |
381 | } | |
382 | ||
383 | /* Read other sides version identification. */ | |
384 | memset(buf, 0, sizeof(buf)); | |
385 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
386 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { | |
387 | log("Did not receive identification string from %s", | |
388 | get_remote_ipaddr()); | |
389 | fatal_cleanup(); | |
390 | } | |
391 | if (buf[i] == '\r') { | |
392 | buf[i] = 0; | |
393 | /* Kludge for F-Secure Macintosh < 1.0.2 */ | |
394 | if (i == 12 && | |
395 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
396 | break; | |
397 | continue; | |
398 | } | |
399 | if (buf[i] == '\n') { | |
400 | buf[i] = 0; | |
401 | break; | |
402 | } | |
403 | } | |
404 | buf[sizeof(buf) - 1] = 0; | |
405 | client_version_string = xstrdup(buf); | |
406 | } | |
407 | ||
408 | /* | |
409 | * Check that the versions match. In future this might accept | |
410 | * several versions and set appropriate flags to handle them. | |
411 | */ | |
412 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
413 | &remote_major, &remote_minor, remote_version) != 3) { | |
414 | s = "Protocol mismatch.\n"; | |
415 | (void) atomicio(write, sock_out, s, strlen(s)); | |
416 | close(sock_in); | |
417 | close(sock_out); | |
418 | log("Bad protocol version identification '%.100s' from %s", | |
419 | client_version_string, get_remote_ipaddr()); | |
420 | fatal_cleanup(); | |
421 | } | |
422 | debug("Client protocol version %d.%d; client software version %.100s", | |
423 | remote_major, remote_minor, remote_version); | |
424 | ||
425 | compat_datafellows(remote_version); | |
426 | ||
427 | if (datafellows & SSH_BUG_PROBE) { | |
428 | log("probed from %s with %s. Don't panic.", | |
429 | get_remote_ipaddr(), client_version_string); | |
430 | fatal_cleanup(); | |
431 | } | |
432 | ||
433 | if (datafellows & SSH_BUG_SCANNER) { | |
434 | log("scanned from %s with %s. Don't panic.", | |
435 | get_remote_ipaddr(), client_version_string); | |
436 | fatal_cleanup(); | |
437 | } | |
438 | ||
439 | mismatch = 0; | |
440 | switch (remote_major) { | |
441 | case 1: | |
442 | if (remote_minor == 99) { | |
443 | if (options.protocol & SSH_PROTO_2) | |
444 | enable_compat20(); | |
445 | else | |
446 | mismatch = 1; | |
447 | break; | |
448 | } | |
449 | if (!(options.protocol & SSH_PROTO_1)) { | |
450 | mismatch = 1; | |
451 | break; | |
452 | } | |
453 | if (remote_minor < 3) { | |
454 | packet_disconnect("Your ssh version is too old and " | |
455 | "is no longer supported. Please install a newer version."); | |
456 | } else if (remote_minor == 3) { | |
457 | /* note that this disables agent-forwarding */ | |
458 | enable_compat13(); | |
459 | } | |
460 | break; | |
461 | case 2: | |
462 | if (options.protocol & SSH_PROTO_2) { | |
463 | enable_compat20(); | |
464 | break; | |
465 | } | |
466 | /* FALLTHROUGH */ | |
467 | default: | |
468 | mismatch = 1; | |
469 | break; | |
470 | } | |
471 | chop(server_version_string); | |
472 | debug("Local version string %.200s", server_version_string); | |
473 | ||
474 | if (mismatch) { | |
475 | s = "Protocol major versions differ.\n"; | |
476 | (void) atomicio(write, sock_out, s, strlen(s)); | |
477 | close(sock_in); | |
478 | close(sock_out); | |
479 | log("Protocol major versions differ for %s: %.200s vs. %.200s", | |
480 | get_remote_ipaddr(), | |
481 | server_version_string, client_version_string); | |
482 | fatal_cleanup(); | |
483 | } | |
484 | } | |
485 | ||
486 | /* Destroy the host and server keys. They will no longer be needed. */ | |
487 | void | |
488 | destroy_sensitive_data(void) | |
489 | { | |
490 | int i; | |
491 | ||
492 | if (sensitive_data.server_key) { | |
493 | key_free(sensitive_data.server_key); | |
494 | sensitive_data.server_key = NULL; | |
495 | } | |
496 | for (i = 0; i < options.num_host_key_files; i++) { | |
497 | if (sensitive_data.host_keys[i]) { | |
498 | key_free(sensitive_data.host_keys[i]); | |
499 | sensitive_data.host_keys[i] = NULL; | |
500 | } | |
501 | } | |
502 | sensitive_data.ssh1_host_key = NULL; | |
503 | memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); | |
504 | } | |
505 | ||
506 | /* Demote private to public keys for network child */ | |
507 | void | |
508 | demote_sensitive_data(void) | |
509 | { | |
510 | Key *tmp; | |
511 | int i; | |
512 | ||
513 | if (sensitive_data.server_key) { | |
514 | tmp = key_demote(sensitive_data.server_key); | |
515 | key_free(sensitive_data.server_key); | |
516 | sensitive_data.server_key = tmp; | |
517 | } | |
518 | ||
519 | for (i = 0; i < options.num_host_key_files; i++) { | |
520 | if (sensitive_data.host_keys[i]) { | |
521 | tmp = key_demote(sensitive_data.host_keys[i]); | |
522 | key_free(sensitive_data.host_keys[i]); | |
523 | sensitive_data.host_keys[i] = tmp; | |
524 | if (tmp->type == KEY_RSA1) | |
525 | sensitive_data.ssh1_host_key = tmp; | |
526 | } | |
527 | } | |
528 | ||
529 | /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ | |
530 | } | |
531 | ||
532 | static void | |
533 | privsep_preauth_child(void) | |
534 | { | |
535 | u_int32_t rnd[256]; | |
536 | gid_t gidset[1]; | |
537 | struct passwd *pw; | |
538 | int i; | |
539 | ||
540 | /* Enable challenge-response authentication for privilege separation */ | |
541 | privsep_challenge_enable(); | |
542 | ||
543 | for (i = 0; i < 256; i++) | |
544 | rnd[i] = arc4random(); | |
545 | RAND_seed(rnd, sizeof(rnd)); | |
546 | ||
547 | /* Demote the private keys to public keys. */ | |
548 | demote_sensitive_data(); | |
549 | ||
550 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
551 | fatal("Privilege separation user %s does not exist", | |
552 | SSH_PRIVSEP_USER); | |
553 | memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); | |
554 | endpwent(); | |
555 | ||
556 | /* Change our root directory */ | |
557 | if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) | |
558 | fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, | |
559 | strerror(errno)); | |
560 | if (chdir("/") == -1) | |
561 | fatal("chdir(\"/\"): %s", strerror(errno)); | |
562 | ||
563 | /* Drop our privileges */ | |
564 | debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, | |
565 | (u_int)pw->pw_gid); | |
566 | #if 0 | |
567 | /* XXX not ready, to heavy after chroot */ | |
568 | do_setusercontext(pw); | |
569 | #else | |
570 | gidset[0] = pw->pw_gid; | |
571 | if (setgid(pw->pw_gid) < 0) | |
572 | fatal("setgid failed for %u", pw->pw_gid ); | |
573 | if (setgroups(1, gidset) < 0) | |
574 | fatal("setgroups: %.100s", strerror(errno)); | |
575 | permanently_set_uid(pw); | |
576 | #endif | |
577 | } | |
578 | ||
579 | static Authctxt * | |
580 | privsep_preauth(void) | |
581 | { | |
582 | Authctxt *authctxt = NULL; | |
583 | int status; | |
584 | pid_t pid; | |
585 | ||
586 | /* Set up unprivileged child process to deal with network data */ | |
587 | pmonitor = monitor_init(); | |
588 | /* Store a pointer to the kex for later rekeying */ | |
589 | pmonitor->m_pkex = &xxx_kex; | |
590 | ||
591 | pid = fork(); | |
592 | if (pid == -1) { | |
593 | fatal("fork of unprivileged child failed"); | |
594 | } else if (pid != 0) { | |
595 | fatal_remove_cleanup((void (*) (void *)) packet_close, NULL); | |
596 | ||
597 | debug2("Network child is on pid %ld", (long)pid); | |
598 | ||
599 | close(pmonitor->m_recvfd); | |
600 | authctxt = monitor_child_preauth(pmonitor); | |
601 | close(pmonitor->m_sendfd); | |
602 | ||
603 | /* Sync memory */ | |
604 | monitor_sync(pmonitor); | |
605 | ||
606 | /* Wait for the child's exit status */ | |
607 | while (waitpid(pid, &status, 0) < 0) | |
608 | if (errno != EINTR) | |
609 | break; | |
610 | ||
611 | /* Reinstall, since the child has finished */ | |
612 | fatal_add_cleanup((void (*) (void *)) packet_close, NULL); | |
613 | ||
614 | return (authctxt); | |
615 | } else { | |
616 | /* child */ | |
617 | ||
618 | close(pmonitor->m_sendfd); | |
619 | ||
620 | /* Demote the child */ | |
621 | if (getuid() == 0 || geteuid() == 0) | |
622 | privsep_preauth_child(); | |
623 | setproctitle("%s", "[net]"); | |
624 | } | |
625 | return (NULL); | |
626 | } | |
627 | ||
628 | static void | |
629 | privsep_postauth(Authctxt *authctxt) | |
630 | { | |
631 | extern Authctxt *x_authctxt; | |
632 | ||
633 | /* XXX - Remote port forwarding */ | |
634 | x_authctxt = authctxt; | |
635 | ||
636 | #ifdef DISABLE_FD_PASSING | |
637 | if (1) { | |
638 | #else | |
639 | if (authctxt->pw->pw_uid == 0 || options.use_login) { | |
640 | #endif | |
641 | /* File descriptor passing is broken or root login */ | |
642 | monitor_apply_keystate(pmonitor); | |
643 | use_privsep = 0; | |
644 | return; | |
645 | } | |
646 | ||
647 | /* Authentication complete */ | |
648 | alarm(0); | |
649 | if (startup_pipe != -1) { | |
650 | close(startup_pipe); | |
651 | startup_pipe = -1; | |
652 | } | |
653 | ||
654 | /* New socket pair */ | |
655 | monitor_reinit(pmonitor); | |
656 | ||
657 | pmonitor->m_pid = fork(); | |
658 | if (pmonitor->m_pid == -1) | |
659 | fatal("fork of unprivileged child failed"); | |
660 | else if (pmonitor->m_pid != 0) { | |
661 | fatal_remove_cleanup((void (*) (void *)) packet_close, NULL); | |
662 | ||
663 | debug2("User child is on pid %ld", (long)pmonitor->m_pid); | |
664 | close(pmonitor->m_recvfd); | |
665 | monitor_child_postauth(pmonitor); | |
666 | ||
667 | /* NEVERREACHED */ | |
668 | exit(0); | |
669 | } | |
670 | ||
671 | close(pmonitor->m_sendfd); | |
672 | ||
673 | /* Demote the private keys to public keys. */ | |
674 | demote_sensitive_data(); | |
675 | ||
676 | /* Drop privileges */ | |
677 | do_setusercontext(authctxt->pw); | |
678 | ||
679 | /* It is safe now to apply the key state */ | |
680 | monitor_apply_keystate(pmonitor); | |
681 | } | |
682 | ||
683 | static char * | |
684 | list_hostkey_types(void) | |
685 | { | |
686 | Buffer b; | |
687 | char *p; | |
688 | int i; | |
689 | ||
690 | buffer_init(&b); | |
691 | for (i = 0; i < options.num_host_key_files; i++) { | |
692 | Key *key = sensitive_data.host_keys[i]; | |
693 | if (key == NULL) | |
694 | continue; | |
695 | switch (key->type) { | |
696 | case KEY_RSA: | |
697 | case KEY_DSA: | |
698 | if (buffer_len(&b) > 0) | |
699 | buffer_append(&b, ",", 1); | |
700 | p = key_ssh_name(key); | |
701 | buffer_append(&b, p, strlen(p)); | |
702 | break; | |
703 | } | |
704 | } | |
705 | buffer_append(&b, "\0", 1); | |
706 | p = xstrdup(buffer_ptr(&b)); | |
707 | buffer_free(&b); | |
708 | debug("list_hostkey_types: %s", p); | |
709 | return p; | |
710 | } | |
711 | ||
712 | Key * | |
713 | get_hostkey_by_type(int type) | |
714 | { | |
715 | int i; | |
716 | ||
717 | for (i = 0; i < options.num_host_key_files; i++) { | |
718 | Key *key = sensitive_data.host_keys[i]; | |
719 | if (key != NULL && key->type == type) | |
720 | return key; | |
721 | } | |
722 | return NULL; | |
723 | } | |
724 | ||
725 | Key * | |
726 | get_hostkey_by_index(int ind) | |
727 | { | |
728 | if (ind < 0 || ind >= options.num_host_key_files) | |
729 | return (NULL); | |
730 | return (sensitive_data.host_keys[ind]); | |
731 | } | |
732 | ||
733 | int | |
734 | get_hostkey_index(Key *key) | |
735 | { | |
736 | int i; | |
737 | ||
738 | for (i = 0; i < options.num_host_key_files; i++) { | |
739 | if (key == sensitive_data.host_keys[i]) | |
740 | return (i); | |
741 | } | |
742 | return (-1); | |
743 | } | |
744 | ||
745 | /* | |
746 | * returns 1 if connection should be dropped, 0 otherwise. | |
747 | * dropping starts at connection #max_startups_begin with a probability | |
748 | * of (max_startups_rate/100). the probability increases linearly until | |
749 | * all connections are dropped for startups > max_startups | |
750 | */ | |
751 | static int | |
752 | drop_connection(int startups) | |
753 | { | |
754 | double p, r; | |
755 | ||
756 | if (startups < options.max_startups_begin) | |
757 | return 0; | |
758 | if (startups >= options.max_startups) | |
759 | return 1; | |
760 | if (options.max_startups_rate == 100) | |
761 | return 1; | |
762 | ||
763 | p = 100 - options.max_startups_rate; | |
764 | p *= startups - options.max_startups_begin; | |
765 | p /= (double) (options.max_startups - options.max_startups_begin); | |
766 | p += options.max_startups_rate; | |
767 | p /= 100.0; | |
768 | r = arc4random() / (double) UINT_MAX; | |
769 | ||
770 | debug("drop_connection: p %g, r %g", p, r); | |
771 | return (r < p) ? 1 : 0; | |
772 | } | |
773 | ||
774 | static void | |
775 | usage(void) | |
776 | { | |
777 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
778 | fprintf(stderr, "Usage: %s [options]\n", __progname); | |
779 | fprintf(stderr, "Options:\n"); | |
780 | fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE); | |
781 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); | |
782 | fprintf(stderr, " -i Started from inetd\n"); | |
783 | fprintf(stderr, " -D Do not fork into daemon mode\n"); | |
784 | fprintf(stderr, " -t Only test configuration file and keys\n"); | |
785 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
786 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
787 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
788 | fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n"); | |
789 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
790 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
791 | _PATH_HOST_KEY_FILE); | |
792 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); | |
793 | fprintf(stderr, " -4 Use IPv4 only\n"); | |
794 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
795 | fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n"); | |
796 | exit(1); | |
797 | } | |
798 | ||
799 | /* | |
800 | * Main program for the daemon. | |
801 | */ | |
802 | int | |
803 | main(int ac, char **av) | |
804 | { | |
805 | extern char *optarg; | |
806 | extern int optind; | |
807 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; | |
808 | pid_t pid; | |
809 | socklen_t fromlen; | |
810 | fd_set *fdset; | |
811 | struct sockaddr_storage from; | |
812 | const char *remote_ip; | |
813 | int remote_port; | |
814 | FILE *f; | |
815 | struct addrinfo *ai; | |
816 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
817 | int listen_sock, maxfd; | |
818 | int startup_p[2]; | |
819 | int startups = 0; | |
820 | Authctxt *authctxt; | |
821 | Key *key; | |
822 | int ret, key_used = 0; | |
823 | ||
824 | #ifdef HAVE_SECUREWARE | |
825 | (void)set_auth_parameters(ac, av); | |
826 | #endif | |
827 | __progname = get_progname(av[0]); | |
828 | init_rng(); | |
829 | ||
830 | /* Save argv. */ | |
831 | saved_argc = ac; | |
832 | saved_argv = av; | |
833 | ||
834 | /* Initialize configuration options to their default values. */ | |
835 | initialize_server_options(&options); | |
836 | ||
837 | /* Parse command-line arguments. */ | |
838 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) { | |
839 | switch (opt) { | |
840 | case '4': | |
841 | IPv4or6 = AF_INET; | |
842 | break; | |
843 | case '6': | |
844 | IPv4or6 = AF_INET6; | |
845 | break; | |
846 | case 'f': | |
847 | config_file_name = optarg; | |
848 | break; | |
849 | case 'd': | |
850 | if (0 == debug_flag) { | |
851 | debug_flag = 1; | |
852 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
853 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
854 | options.log_level++; | |
855 | } else { | |
856 | fprintf(stderr, "Too high debugging level.\n"); | |
857 | exit(1); | |
858 | } | |
859 | break; | |
860 | case 'D': | |
861 | no_daemon_flag = 1; | |
862 | break; | |
863 | case 'e': | |
864 | log_stderr = 1; | |
865 | break; | |
866 | case 'i': | |
867 | inetd_flag = 1; | |
868 | break; | |
869 | case 'Q': | |
870 | /* ignored */ | |
871 | break; | |
872 | case 'q': | |
873 | options.log_level = SYSLOG_LEVEL_QUIET; | |
874 | break; | |
875 | case 'b': | |
876 | options.server_key_bits = atoi(optarg); | |
877 | break; | |
878 | case 'p': | |
879 | options.ports_from_cmdline = 1; | |
880 | if (options.num_ports >= MAX_PORTS) { | |
881 | fprintf(stderr, "too many ports.\n"); | |
882 | exit(1); | |
883 | } | |
884 | options.ports[options.num_ports++] = a2port(optarg); | |
885 | if (options.ports[options.num_ports-1] == 0) { | |
886 | fprintf(stderr, "Bad port number.\n"); | |
887 | exit(1); | |
888 | } | |
889 | break; | |
890 | case 'g': | |
891 | if ((options.login_grace_time = convtime(optarg)) == -1) { | |
892 | fprintf(stderr, "Invalid login grace time.\n"); | |
893 | exit(1); | |
894 | } | |
895 | break; | |
896 | case 'k': | |
897 | if ((options.key_regeneration_time = convtime(optarg)) == -1) { | |
898 | fprintf(stderr, "Invalid key regeneration interval.\n"); | |
899 | exit(1); | |
900 | } | |
901 | break; | |
902 | case 'h': | |
903 | if (options.num_host_key_files >= MAX_HOSTKEYS) { | |
904 | fprintf(stderr, "too many host keys.\n"); | |
905 | exit(1); | |
906 | } | |
907 | options.host_key_files[options.num_host_key_files++] = optarg; | |
908 | break; | |
909 | case 'V': | |
910 | client_version_string = optarg; | |
911 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
912 | inetd_flag = 1; | |
913 | break; | |
914 | case 't': | |
915 | test_flag = 1; | |
916 | break; | |
917 | case 'u': | |
918 | utmp_len = atoi(optarg); | |
919 | if (utmp_len > MAXHOSTNAMELEN) { | |
920 | fprintf(stderr, "Invalid utmp length.\n"); | |
921 | exit(1); | |
922 | } | |
923 | break; | |
924 | case 'o': | |
925 | if (process_server_config_line(&options, optarg, | |
926 | "command-line", 0) != 0) | |
927 | exit(1); | |
928 | break; | |
929 | case '?': | |
930 | default: | |
931 | usage(); | |
932 | break; | |
933 | } | |
934 | } | |
935 | SSLeay_add_all_algorithms(); | |
936 | channel_set_af(IPv4or6); | |
937 | ||
938 | /* | |
939 | * Force logging to stderr until we have loaded the private host | |
940 | * key (unless started from inetd) | |
941 | */ | |
942 | log_init(__progname, | |
943 | options.log_level == SYSLOG_LEVEL_NOT_SET ? | |
944 | SYSLOG_LEVEL_INFO : options.log_level, | |
945 | options.log_facility == SYSLOG_FACILITY_NOT_SET ? | |
946 | SYSLOG_FACILITY_AUTH : options.log_facility, | |
947 | !inetd_flag); | |
948 | ||
949 | #ifdef _UNICOS | |
950 | /* Cray can define user privs drop all prives now! | |
951 | * Not needed on PRIV_SU systems! | |
952 | */ | |
953 | drop_cray_privs(); | |
954 | #endif | |
955 | ||
956 | seed_rng(); | |
957 | ||
958 | /* Read server configuration options from the configuration file. */ | |
959 | read_server_config(&options, config_file_name); | |
960 | ||
961 | /* Fill in default values for those options not explicitly set. */ | |
962 | fill_default_server_options(&options); | |
963 | ||
964 | /* Check that there are no remaining arguments. */ | |
965 | if (optind < ac) { | |
966 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
967 | exit(1); | |
968 | } | |
969 | ||
970 | debug("sshd version %.100s", SSH_VERSION); | |
971 | ||
972 | /* load private host keys */ | |
973 | sensitive_data.host_keys = xmalloc(options.num_host_key_files * | |
974 | sizeof(Key *)); | |
975 | for (i = 0; i < options.num_host_key_files; i++) | |
976 | sensitive_data.host_keys[i] = NULL; | |
977 | sensitive_data.server_key = NULL; | |
978 | sensitive_data.ssh1_host_key = NULL; | |
979 | sensitive_data.have_ssh1_key = 0; | |
980 | sensitive_data.have_ssh2_key = 0; | |
981 | ||
982 | for (i = 0; i < options.num_host_key_files; i++) { | |
983 | key = key_load_private(options.host_key_files[i], "", NULL); | |
984 | sensitive_data.host_keys[i] = key; | |
985 | if (key == NULL) { | |
986 | error("Could not load host key: %s", | |
987 | options.host_key_files[i]); | |
988 | sensitive_data.host_keys[i] = NULL; | |
989 | continue; | |
990 | } | |
991 | switch (key->type) { | |
992 | case KEY_RSA1: | |
993 | sensitive_data.ssh1_host_key = key; | |
994 | sensitive_data.have_ssh1_key = 1; | |
995 | break; | |
996 | case KEY_RSA: | |
997 | case KEY_DSA: | |
998 | sensitive_data.have_ssh2_key = 1; | |
999 | break; | |
1000 | } | |
1001 | debug("private host key: #%d type %d %s", i, key->type, | |
1002 | key_type(key)); | |
1003 | } | |
1004 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
1005 | log("Disabling protocol version 1. Could not load host key"); | |
1006 | options.protocol &= ~SSH_PROTO_1; | |
1007 | } | |
1008 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
1009 | log("Disabling protocol version 2. Could not load host key"); | |
1010 | options.protocol &= ~SSH_PROTO_2; | |
1011 | } | |
1012 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { | |
1013 | log("sshd: no hostkeys available -- exiting."); | |
1014 | exit(1); | |
1015 | } | |
1016 | ||
1017 | /* Check certain values for sanity. */ | |
1018 | if (options.protocol & SSH_PROTO_1) { | |
1019 | if (options.server_key_bits < 512 || | |
1020 | options.server_key_bits > 32768) { | |
1021 | fprintf(stderr, "Bad server key size.\n"); | |
1022 | exit(1); | |
1023 | } | |
1024 | /* | |
1025 | * Check that server and host key lengths differ sufficiently. This | |
1026 | * is necessary to make double encryption work with rsaref. Oh, I | |
1027 | * hate software patents. I dont know if this can go? Niels | |
1028 | */ | |
1029 | if (options.server_key_bits > | |
1030 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - | |
1031 | SSH_KEY_BITS_RESERVED && options.server_key_bits < | |
1032 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1033 | SSH_KEY_BITS_RESERVED) { | |
1034 | options.server_key_bits = | |
1035 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1036 | SSH_KEY_BITS_RESERVED; | |
1037 | debug("Forcing server key to %d bits to make it differ from host key.", | |
1038 | options.server_key_bits); | |
1039 | } | |
1040 | } | |
1041 | ||
1042 | if (use_privsep) { | |
1043 | struct passwd *pw; | |
1044 | struct stat st; | |
1045 | ||
1046 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
1047 | fatal("Privilege separation user %s does not exist", | |
1048 | SSH_PRIVSEP_USER); | |
1049 | if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || | |
1050 | (S_ISDIR(st.st_mode) == 0)) | |
1051 | fatal("Missing privilege separation directory: %s", | |
1052 | _PATH_PRIVSEP_CHROOT_DIR); | |
1053 | ||
1054 | #ifdef HAVE_CYGWIN | |
1055 | if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && | |
1056 | (st.st_uid != getuid () || | |
1057 | (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) | |
1058 | #else | |
1059 | if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) | |
1060 | #endif | |
1061 | fatal("Bad owner or mode for %s", | |
1062 | _PATH_PRIVSEP_CHROOT_DIR); | |
1063 | } | |
1064 | ||
1065 | /* Configuration looks good, so exit if in test mode. */ | |
1066 | if (test_flag) | |
1067 | exit(0); | |
1068 | ||
1069 | /* | |
1070 | * Clear out any supplemental groups we may have inherited. This | |
1071 | * prevents inadvertent creation of files with bad modes (in the | |
1072 | * portable version at least, it's certainly possible for PAM | |
1073 | * to create a file, and we can't control the code in every | |
1074 | * module which might be used). | |
1075 | */ | |
1076 | if (setgroups(0, NULL) < 0) | |
1077 | debug("setgroups() failed: %.200s", strerror(errno)); | |
1078 | ||
1079 | /* Initialize the log (it is reinitialized below in case we forked). */ | |
1080 | if (debug_flag && !inetd_flag) | |
1081 | log_stderr = 1; | |
1082 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1083 | ||
1084 | /* | |
1085 | * If not in debugging mode, and not started from inetd, disconnect | |
1086 | * from the controlling terminal, and fork. The original process | |
1087 | * exits. | |
1088 | */ | |
1089 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { | |
1090 | #ifdef TIOCNOTTY | |
1091 | int fd; | |
1092 | #endif /* TIOCNOTTY */ | |
1093 | if (daemon(0, 0) < 0) | |
1094 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1095 | ||
1096 | /* Disconnect from the controlling tty. */ | |
1097 | #ifdef TIOCNOTTY | |
1098 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); | |
1099 | if (fd >= 0) { | |
1100 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
1101 | close(fd); | |
1102 | } | |
1103 | #endif /* TIOCNOTTY */ | |
1104 | } | |
1105 | /* Reinitialize the log (because of the fork above). */ | |
1106 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1107 | ||
1108 | /* Initialize the random number generator. */ | |
1109 | arc4random_stir(); | |
1110 | ||
1111 | /* Chdir to the root directory so that the current disk can be | |
1112 | unmounted if desired. */ | |
1113 | chdir("/"); | |
1114 | ||
1115 | /* ignore SIGPIPE */ | |
1116 | signal(SIGPIPE, SIG_IGN); | |
1117 | ||
1118 | /* Start listening for a socket, unless started from inetd. */ | |
1119 | if (inetd_flag) { | |
1120 | int s1; | |
1121 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ | |
1122 | dup(s1); | |
1123 | sock_in = dup(0); | |
1124 | sock_out = dup(1); | |
1125 | startup_pipe = -1; | |
1126 | /* | |
1127 | * We intentionally do not close the descriptors 0, 1, and 2 | |
1128 | * as our code for setting the descriptors won\'t work if | |
1129 | * ttyfd happens to be one of those. | |
1130 | */ | |
1131 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); | |
1132 | if (options.protocol & SSH_PROTO_1) | |
1133 | generate_ephemeral_server_key(); | |
1134 | } else { | |
1135 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { | |
1136 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
1137 | continue; | |
1138 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
1139 | fatal("Too many listen sockets. " | |
1140 | "Enlarge MAX_LISTEN_SOCKS"); | |
1141 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
1142 | ntop, sizeof(ntop), strport, sizeof(strport), | |
1143 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
1144 | error("getnameinfo failed"); | |
1145 | continue; | |
1146 | } | |
1147 | /* Create socket for listening. */ | |
1148 | listen_sock = socket(ai->ai_family, SOCK_STREAM, 0); | |
1149 | if (listen_sock < 0) { | |
1150 | /* kernel may not support ipv6 */ | |
1151 | verbose("socket: %.100s", strerror(errno)); | |
1152 | continue; | |
1153 | } | |
1154 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
1155 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
1156 | close(listen_sock); | |
1157 | continue; | |
1158 | } | |
1159 | /* | |
1160 | * Set socket options. | |
1161 | * Allow local port reuse in TIME_WAIT. | |
1162 | */ | |
1163 | if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, | |
1164 | &on, sizeof(on)) == -1) | |
1165 | error("setsockopt SO_REUSEADDR: %s", strerror(errno)); | |
1166 | ||
1167 | debug("Bind to port %s on %s.", strport, ntop); | |
1168 | ||
1169 | /* Bind the socket to the desired port. */ | |
1170 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { | |
1171 | if (!ai->ai_next) | |
1172 | error("Bind to port %s on %s failed: %.200s.", | |
1173 | strport, ntop, strerror(errno)); | |
1174 | close(listen_sock); | |
1175 | continue; | |
1176 | } | |
1177 | listen_socks[num_listen_socks] = listen_sock; | |
1178 | num_listen_socks++; | |
1179 | ||
1180 | /* Start listening on the port. */ | |
1181 | log("Server listening on %s port %s.", ntop, strport); | |
1182 | if (listen(listen_sock, 5) < 0) | |
1183 | fatal("listen: %.100s", strerror(errno)); | |
1184 | ||
1185 | } | |
1186 | freeaddrinfo(options.listen_addrs); | |
1187 | ||
1188 | if (!num_listen_socks) | |
1189 | fatal("Cannot bind any address."); | |
1190 | ||
1191 | if (options.protocol & SSH_PROTO_1) | |
1192 | generate_ephemeral_server_key(); | |
1193 | ||
1194 | /* | |
1195 | * Arrange to restart on SIGHUP. The handler needs | |
1196 | * listen_sock. | |
1197 | */ | |
1198 | signal(SIGHUP, sighup_handler); | |
1199 | ||
1200 | signal(SIGTERM, sigterm_handler); | |
1201 | signal(SIGQUIT, sigterm_handler); | |
1202 | ||
1203 | /* Arrange SIGCHLD to be caught. */ | |
1204 | signal(SIGCHLD, main_sigchld_handler); | |
1205 | ||
1206 | /* Write out the pid file after the sigterm handler is setup */ | |
1207 | if (!debug_flag) { | |
1208 | /* | |
1209 | * Record our pid in /var/run/sshd.pid to make it | |
1210 | * easier to kill the correct sshd. We don't want to | |
1211 | * do this before the bind above because the bind will | |
1212 | * fail if there already is a daemon, and this will | |
1213 | * overwrite any old pid in the file. | |
1214 | */ | |
1215 | f = fopen(options.pid_file, "wb"); | |
1216 | if (f) { | |
1217 | fprintf(f, "%ld\n", (long) getpid()); | |
1218 | fclose(f); | |
1219 | } | |
1220 | } | |
1221 | ||
1222 | /* setup fd set for listen */ | |
1223 | fdset = NULL; | |
1224 | maxfd = 0; | |
1225 | for (i = 0; i < num_listen_socks; i++) | |
1226 | if (listen_socks[i] > maxfd) | |
1227 | maxfd = listen_socks[i]; | |
1228 | /* pipes connected to unauthenticated childs */ | |
1229 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
1230 | for (i = 0; i < options.max_startups; i++) | |
1231 | startup_pipes[i] = -1; | |
1232 | ||
1233 | /* | |
1234 | * Stay listening for connections until the system crashes or | |
1235 | * the daemon is killed with a signal. | |
1236 | */ | |
1237 | for (;;) { | |
1238 | if (received_sighup) | |
1239 | sighup_restart(); | |
1240 | if (fdset != NULL) | |
1241 | xfree(fdset); | |
1242 | fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); | |
1243 | fdset = (fd_set *)xmalloc(fdsetsz); | |
1244 | memset(fdset, 0, fdsetsz); | |
1245 | ||
1246 | for (i = 0; i < num_listen_socks; i++) | |
1247 | FD_SET(listen_socks[i], fdset); | |
1248 | for (i = 0; i < options.max_startups; i++) | |
1249 | if (startup_pipes[i] != -1) | |
1250 | FD_SET(startup_pipes[i], fdset); | |
1251 | ||
1252 | /* Wait in select until there is a connection. */ | |
1253 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); | |
1254 | if (ret < 0 && errno != EINTR) | |
1255 | error("select: %.100s", strerror(errno)); | |
1256 | if (received_sigterm) { | |
1257 | log("Received signal %d; terminating.", | |
1258 | (int) received_sigterm); | |
1259 | close_listen_socks(); | |
1260 | unlink(options.pid_file); | |
1261 | exit(255); | |
1262 | } | |
1263 | if (key_used && key_do_regen) { | |
1264 | generate_ephemeral_server_key(); | |
1265 | key_used = 0; | |
1266 | key_do_regen = 0; | |
1267 | } | |
1268 | if (ret < 0) | |
1269 | continue; | |
1270 | ||
1271 | for (i = 0; i < options.max_startups; i++) | |
1272 | if (startup_pipes[i] != -1 && | |
1273 | FD_ISSET(startup_pipes[i], fdset)) { | |
1274 | /* | |
1275 | * the read end of the pipe is ready | |
1276 | * if the child has closed the pipe | |
1277 | * after successful authentication | |
1278 | * or if the child has died | |
1279 | */ | |
1280 | close(startup_pipes[i]); | |
1281 | startup_pipes[i] = -1; | |
1282 | startups--; | |
1283 | } | |
1284 | for (i = 0; i < num_listen_socks; i++) { | |
1285 | if (!FD_ISSET(listen_socks[i], fdset)) | |
1286 | continue; | |
1287 | fromlen = sizeof(from); | |
1288 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
1289 | &fromlen); | |
1290 | if (newsock < 0) { | |
1291 | if (errno != EINTR && errno != EWOULDBLOCK) | |
1292 | error("accept: %.100s", strerror(errno)); | |
1293 | continue; | |
1294 | } | |
1295 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
1296 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
1297 | close(newsock); | |
1298 | continue; | |
1299 | } | |
1300 | if (drop_connection(startups) == 1) { | |
1301 | debug("drop connection #%d", startups); | |
1302 | close(newsock); | |
1303 | continue; | |
1304 | } | |
1305 | if (pipe(startup_p) == -1) { | |
1306 | close(newsock); | |
1307 | continue; | |
1308 | } | |
1309 | ||
1310 | for (j = 0; j < options.max_startups; j++) | |
1311 | if (startup_pipes[j] == -1) { | |
1312 | startup_pipes[j] = startup_p[0]; | |
1313 | if (maxfd < startup_p[0]) | |
1314 | maxfd = startup_p[0]; | |
1315 | startups++; | |
1316 | break; | |
1317 | } | |
1318 | ||
1319 | /* | |
1320 | * Got connection. Fork a child to handle it, unless | |
1321 | * we are in debugging mode. | |
1322 | */ | |
1323 | if (debug_flag) { | |
1324 | /* | |
1325 | * In debugging mode. Close the listening | |
1326 | * socket, and start processing the | |
1327 | * connection without forking. | |
1328 | */ | |
1329 | debug("Server will not fork when running in debugging mode."); | |
1330 | close_listen_socks(); | |
1331 | sock_in = newsock; | |
1332 | sock_out = newsock; | |
1333 | startup_pipe = -1; | |
1334 | pid = getpid(); | |
1335 | break; | |
1336 | } else { | |
1337 | /* | |
1338 | * Normal production daemon. Fork, and have | |
1339 | * the child process the connection. The | |
1340 | * parent continues listening. | |
1341 | */ | |
1342 | if ((pid = fork()) == 0) { | |
1343 | /* | |
1344 | * Child. Close the listening and max_startup | |
1345 | * sockets. Start using the accepted socket. | |
1346 | * Reinitialize logging (since our pid has | |
1347 | * changed). We break out of the loop to handle | |
1348 | * the connection. | |
1349 | */ | |
1350 | startup_pipe = startup_p[1]; | |
1351 | close_startup_pipes(); | |
1352 | close_listen_socks(); | |
1353 | sock_in = newsock; | |
1354 | sock_out = newsock; | |
1355 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1356 | break; | |
1357 | } | |
1358 | } | |
1359 | ||
1360 | /* Parent. Stay in the loop. */ | |
1361 | if (pid < 0) | |
1362 | error("fork: %.100s", strerror(errno)); | |
1363 | else | |
1364 | debug("Forked child %ld.", (long)pid); | |
1365 | ||
1366 | close(startup_p[1]); | |
1367 | ||
1368 | /* Mark that the key has been used (it was "given" to the child). */ | |
1369 | if ((options.protocol & SSH_PROTO_1) && | |
1370 | key_used == 0) { | |
1371 | /* Schedule server key regeneration alarm. */ | |
1372 | signal(SIGALRM, key_regeneration_alarm); | |
1373 | alarm(options.key_regeneration_time); | |
1374 | key_used = 1; | |
1375 | } | |
1376 | ||
1377 | arc4random_stir(); | |
1378 | ||
1379 | /* Close the new socket (the child is now taking care of it). */ | |
1380 | close(newsock); | |
1381 | } | |
1382 | /* child process check (or debug mode) */ | |
1383 | if (num_listen_socks < 0) | |
1384 | break; | |
1385 | } | |
1386 | } | |
1387 | ||
1388 | /* This is the child processing a new connection. */ | |
1389 | ||
1390 | /* | |
1391 | * Create a new session and process group since the 4.4BSD | |
1392 | * setlogin() affects the entire process group. We don't | |
1393 | * want the child to be able to affect the parent. | |
1394 | */ | |
1395 | #if 0 | |
1396 | /* XXX: this breaks Solaris */ | |
1397 | if (!debug_flag && !inetd_flag && setsid() < 0) | |
1398 | error("setsid: %.100s", strerror(errno)); | |
1399 | #endif | |
1400 | ||
1401 | /* | |
1402 | * Disable the key regeneration alarm. We will not regenerate the | |
1403 | * key since we are no longer in a position to give it to anyone. We | |
1404 | * will not restart on SIGHUP since it no longer makes sense. | |
1405 | */ | |
1406 | alarm(0); | |
1407 | signal(SIGALRM, SIG_DFL); | |
1408 | signal(SIGHUP, SIG_DFL); | |
1409 | signal(SIGTERM, SIG_DFL); | |
1410 | signal(SIGQUIT, SIG_DFL); | |
1411 | signal(SIGCHLD, SIG_DFL); | |
1412 | signal(SIGINT, SIG_DFL); | |
1413 | ||
1414 | /* Set keepalives if requested. */ | |
1415 | if (options.keepalives && | |
1416 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, | |
1417 | sizeof(on)) < 0) | |
1418 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1419 | ||
1420 | /* | |
1421 | * Register our connection. This turns encryption off because we do | |
1422 | * not have a key. | |
1423 | */ | |
1424 | packet_set_connection(sock_in, sock_out); | |
1425 | ||
1426 | remote_port = get_remote_port(); | |
1427 | remote_ip = get_remote_ipaddr(); | |
1428 | ||
1429 | #ifdef LIBWRAP | |
1430 | /* Check whether logins are denied from this host. */ | |
1431 | { | |
1432 | struct request_info req; | |
1433 | ||
1434 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); | |
1435 | fromhost(&req); | |
1436 | ||
1437 | if (!hosts_access(&req)) { | |
1438 | debug("Connection refused by tcp wrapper"); | |
1439 | refuse(&req); | |
1440 | /* NOTREACHED */ | |
1441 | fatal("libwrap refuse returns"); | |
1442 | } | |
1443 | } | |
1444 | #endif /* LIBWRAP */ | |
1445 | ||
1446 | /* Log the connection. */ | |
1447 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
1448 | ||
1449 | /* | |
1450 | * We don\'t want to listen forever unless the other side | |
1451 | * successfully authenticates itself. So we set up an alarm which is | |
1452 | * cleared after successful authentication. A limit of zero | |
1453 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1454 | * mode; it is just annoying to have the server exit just when you | |
1455 | * are about to discover the bug. | |
1456 | */ | |
1457 | signal(SIGALRM, grace_alarm_handler); | |
1458 | if (!debug_flag) | |
1459 | alarm(options.login_grace_time); | |
1460 | ||
1461 | sshd_exchange_identification(sock_in, sock_out); | |
1462 | /* | |
1463 | * Check that the connection comes from a privileged port. | |
1464 | * Rhosts-Authentication only makes sense from privileged | |
1465 | * programs. Of course, if the intruder has root access on his local | |
1466 | * machine, he can connect from any port. So do not use these | |
1467 | * authentication methods from machines that you do not trust. | |
1468 | */ | |
1469 | if (options.rhosts_authentication && | |
1470 | (remote_port >= IPPORT_RESERVED || | |
1471 | remote_port < IPPORT_RESERVED / 2)) { | |
1472 | debug("Rhosts Authentication disabled, " | |
1473 | "originating port %d not trusted.", remote_port); | |
1474 | options.rhosts_authentication = 0; | |
1475 | } | |
1476 | #if defined(KRB4) && !defined(KRB5) | |
1477 | if (!packet_connection_is_ipv4() && | |
1478 | options.kerberos_authentication) { | |
1479 | debug("Kerberos Authentication disabled, only available for IPv4."); | |
1480 | options.kerberos_authentication = 0; | |
1481 | } | |
1482 | #endif /* KRB4 && !KRB5 */ | |
1483 | #ifdef AFS | |
1484 | /* If machine has AFS, set process authentication group. */ | |
1485 | if (k_hasafs()) { | |
1486 | k_setpag(); | |
1487 | k_unlog(); | |
1488 | } | |
1489 | #endif /* AFS */ | |
1490 | ||
1491 | packet_set_nonblocking(); | |
1492 | ||
1493 | if (use_privsep) | |
1494 | if ((authctxt = privsep_preauth()) != NULL) | |
1495 | goto authenticated; | |
1496 | ||
1497 | /* perform the key exchange */ | |
1498 | /* authenticate user and start session */ | |
1499 | if (compat20) { | |
1500 | do_ssh2_kex(); | |
1501 | authctxt = do_authentication2(); | |
1502 | } else { | |
1503 | do_ssh1_kex(); | |
1504 | authctxt = do_authentication(); | |
1505 | } | |
1506 | /* | |
1507 | * If we use privilege separation, the unprivileged child transfers | |
1508 | * the current keystate and exits | |
1509 | */ | |
1510 | if (use_privsep) { | |
1511 | mm_send_keystate(pmonitor); | |
1512 | exit(0); | |
1513 | } | |
1514 | ||
1515 | authenticated: | |
1516 | /* | |
1517 | * In privilege separation, we fork another child and prepare | |
1518 | * file descriptor passing. | |
1519 | */ | |
1520 | if (use_privsep) { | |
1521 | privsep_postauth(authctxt); | |
1522 | /* the monitor process [priv] will not return */ | |
1523 | if (!compat20) | |
1524 | destroy_sensitive_data(); | |
1525 | } | |
1526 | ||
1527 | /* Perform session preparation. */ | |
1528 | do_authenticated(authctxt); | |
1529 | ||
1530 | /* The connection has been terminated. */ | |
1531 | verbose("Closing connection to %.100s", remote_ip); | |
1532 | ||
1533 | #ifdef USE_PAM | |
1534 | finish_pam(); | |
1535 | #endif /* USE_PAM */ | |
1536 | ||
1537 | packet_close(); | |
1538 | ||
1539 | if (use_privsep) | |
1540 | mm_terminate(); | |
1541 | ||
1542 | exit(0); | |
1543 | } | |
1544 | ||
1545 | /* | |
1546 | * Decrypt session_key_int using our private server key and private host key | |
1547 | * (key with larger modulus first). | |
1548 | */ | |
1549 | int | |
1550 | ssh1_session_key(BIGNUM *session_key_int) | |
1551 | { | |
1552 | int rsafail = 0; | |
1553 | ||
1554 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { | |
1555 | /* Server key has bigger modulus. */ | |
1556 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < | |
1557 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1558 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1559 | get_remote_ipaddr(), | |
1560 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1561 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1562 | SSH_KEY_BITS_RESERVED); | |
1563 | } | |
1564 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1565 | sensitive_data.server_key->rsa) <= 0) | |
1566 | rsafail++; | |
1567 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1568 | sensitive_data.ssh1_host_key->rsa) <= 0) | |
1569 | rsafail++; | |
1570 | } else { | |
1571 | /* Host key has bigger modulus (or they are equal). */ | |
1572 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < | |
1573 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1574 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1575 | get_remote_ipaddr(), | |
1576 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1577 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1578 | SSH_KEY_BITS_RESERVED); | |
1579 | } | |
1580 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1581 | sensitive_data.ssh1_host_key->rsa) < 0) | |
1582 | rsafail++; | |
1583 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1584 | sensitive_data.server_key->rsa) < 0) | |
1585 | rsafail++; | |
1586 | } | |
1587 | return (rsafail); | |
1588 | } | |
1589 | /* | |
1590 | * SSH1 key exchange | |
1591 | */ | |
1592 | static void | |
1593 | do_ssh1_kex(void) | |
1594 | { | |
1595 | int i, len; | |
1596 | int rsafail = 0; | |
1597 | BIGNUM *session_key_int; | |
1598 | u_char session_key[SSH_SESSION_KEY_LENGTH]; | |
1599 | u_char cookie[8]; | |
1600 | u_int cipher_type, auth_mask, protocol_flags; | |
1601 | u_int32_t rnd = 0; | |
1602 | ||
1603 | /* | |
1604 | * Generate check bytes that the client must send back in the user | |
1605 | * packet in order for it to be accepted; this is used to defy ip | |
1606 | * spoofing attacks. Note that this only works against somebody | |
1607 | * doing IP spoofing from a remote machine; any machine on the local | |
1608 | * network can still see outgoing packets and catch the random | |
1609 | * cookie. This only affects rhosts authentication, and this is one | |
1610 | * of the reasons why it is inherently insecure. | |
1611 | */ | |
1612 | for (i = 0; i < 8; i++) { | |
1613 | if (i % 4 == 0) | |
1614 | rnd = arc4random(); | |
1615 | cookie[i] = rnd & 0xff; | |
1616 | rnd >>= 8; | |
1617 | } | |
1618 | ||
1619 | /* | |
1620 | * Send our public key. We include in the packet 64 bits of random | |
1621 | * data that must be matched in the reply in order to prevent IP | |
1622 | * spoofing. | |
1623 | */ | |
1624 | packet_start(SSH_SMSG_PUBLIC_KEY); | |
1625 | for (i = 0; i < 8; i++) | |
1626 | packet_put_char(cookie[i]); | |
1627 | ||
1628 | /* Store our public server RSA key. */ | |
1629 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); | |
1630 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1631 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
1632 | ||
1633 | /* Store our public host RSA key. */ | |
1634 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
1635 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1636 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
1637 | ||
1638 | /* Put protocol flags. */ | |
1639 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1640 | ||
1641 | /* Declare which ciphers we support. */ | |
1642 | packet_put_int(cipher_mask_ssh1(0)); | |
1643 | ||
1644 | /* Declare supported authentication types. */ | |
1645 | auth_mask = 0; | |
1646 | if (options.rhosts_authentication) | |
1647 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
1648 | if (options.rhosts_rsa_authentication) | |
1649 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1650 | if (options.rsa_authentication) | |
1651 | auth_mask |= 1 << SSH_AUTH_RSA; | |
1652 | #if defined(KRB4) || defined(KRB5) | |
1653 | if (options.kerberos_authentication) | |
1654 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
1655 | #endif | |
1656 | #if defined(AFS) || defined(KRB5) | |
1657 | if (options.kerberos_tgt_passing) | |
1658 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
1659 | #endif | |
1660 | #ifdef AFS | |
1661 | if (options.afs_token_passing) | |
1662 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
1663 | #endif | |
1664 | if (options.challenge_response_authentication == 1) | |
1665 | auth_mask |= 1 << SSH_AUTH_TIS; | |
1666 | if (options.password_authentication) | |
1667 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1668 | packet_put_int(auth_mask); | |
1669 | ||
1670 | /* Send the packet and wait for it to be sent. */ | |
1671 | packet_send(); | |
1672 | packet_write_wait(); | |
1673 | ||
1674 | debug("Sent %d bit server key and %d bit host key.", | |
1675 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1676 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
1677 | ||
1678 | /* Read clients reply (cipher type and session key). */ | |
1679 | packet_read_expect(SSH_CMSG_SESSION_KEY); | |
1680 | ||
1681 | /* Get cipher type and check whether we accept this. */ | |
1682 | cipher_type = packet_get_char(); | |
1683 | ||
1684 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) | |
1685 | packet_disconnect("Warning: client selects unsupported cipher."); | |
1686 | ||
1687 | /* Get check bytes from the packet. These must match those we | |
1688 | sent earlier with the public key packet. */ | |
1689 | for (i = 0; i < 8; i++) | |
1690 | if (cookie[i] != packet_get_char()) | |
1691 | packet_disconnect("IP Spoofing check bytes do not match."); | |
1692 | ||
1693 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1694 | ||
1695 | /* Get the encrypted integer. */ | |
1696 | if ((session_key_int = BN_new()) == NULL) | |
1697 | fatal("do_ssh1_kex: BN_new failed"); | |
1698 | packet_get_bignum(session_key_int); | |
1699 | ||
1700 | protocol_flags = packet_get_int(); | |
1701 | packet_set_protocol_flags(protocol_flags); | |
1702 | packet_check_eom(); | |
1703 | ||
1704 | /* Decrypt session_key_int using host/server keys */ | |
1705 | rsafail = PRIVSEP(ssh1_session_key(session_key_int)); | |
1706 | ||
1707 | /* | |
1708 | * Extract session key from the decrypted integer. The key is in the | |
1709 | * least significant 256 bits of the integer; the first byte of the | |
1710 | * key is in the highest bits. | |
1711 | */ | |
1712 | if (!rsafail) { | |
1713 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
1714 | len = BN_num_bytes(session_key_int); | |
1715 | if (len < 0 || len > sizeof(session_key)) { | |
1716 | error("do_connection: bad session key len from %s: " | |
1717 | "session_key_int %d > sizeof(session_key) %lu", | |
1718 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); | |
1719 | rsafail++; | |
1720 | } else { | |
1721 | memset(session_key, 0, sizeof(session_key)); | |
1722 | BN_bn2bin(session_key_int, | |
1723 | session_key + sizeof(session_key) - len); | |
1724 | ||
1725 | compute_session_id(session_id, cookie, | |
1726 | sensitive_data.ssh1_host_key->rsa->n, | |
1727 | sensitive_data.server_key->rsa->n); | |
1728 | /* | |
1729 | * Xor the first 16 bytes of the session key with the | |
1730 | * session id. | |
1731 | */ | |
1732 | for (i = 0; i < 16; i++) | |
1733 | session_key[i] ^= session_id[i]; | |
1734 | } | |
1735 | } | |
1736 | if (rsafail) { | |
1737 | int bytes = BN_num_bytes(session_key_int); | |
1738 | u_char *buf = xmalloc(bytes); | |
1739 | MD5_CTX md; | |
1740 | ||
1741 | log("do_connection: generating a fake encryption key"); | |
1742 | BN_bn2bin(session_key_int, buf); | |
1743 | MD5_Init(&md); | |
1744 | MD5_Update(&md, buf, bytes); | |
1745 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1746 | MD5_Final(session_key, &md); | |
1747 | MD5_Init(&md); | |
1748 | MD5_Update(&md, session_key, 16); | |
1749 | MD5_Update(&md, buf, bytes); | |
1750 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1751 | MD5_Final(session_key + 16, &md); | |
1752 | memset(buf, 0, bytes); | |
1753 | xfree(buf); | |
1754 | for (i = 0; i < 16; i++) | |
1755 | session_id[i] = session_key[i] ^ session_key[i + 16]; | |
1756 | } | |
1757 | /* Destroy the private and public keys. No longer. */ | |
1758 | destroy_sensitive_data(); | |
1759 | ||
1760 | if (use_privsep) | |
1761 | mm_ssh1_session_id(session_id); | |
1762 | ||
1763 | /* Destroy the decrypted integer. It is no longer needed. */ | |
1764 | BN_clear_free(session_key_int); | |
1765 | ||
1766 | /* Set the session key. From this on all communications will be encrypted. */ | |
1767 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1768 | ||
1769 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1770 | memset(session_key, 0, sizeof(session_key)); | |
1771 | ||
1772 | debug("Received session key; encryption turned on."); | |
1773 | ||
1774 | /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ | |
1775 | packet_start(SSH_SMSG_SUCCESS); | |
1776 | packet_send(); | |
1777 | packet_write_wait(); | |
1778 | } | |
1779 | ||
1780 | /* | |
1781 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1782 | */ | |
1783 | static void | |
1784 | do_ssh2_kex(void) | |
1785 | { | |
1786 | Kex *kex; | |
1787 | ||
1788 | if (options.ciphers != NULL) { | |
1789 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
1790 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; | |
1791 | } | |
1792 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
1793 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); | |
1794 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
1795 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); | |
1796 | ||
1797 | if (options.macs != NULL) { | |
1798 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
1799 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
1800 | } | |
1801 | if (!options.compression) { | |
1802 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
1803 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
1804 | } | |
1805 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); | |
1806 | ||
1807 | /* start key exchange */ | |
1808 | kex = kex_setup(myproposal); | |
1809 | kex->server = 1; | |
1810 | kex->client_version_string=client_version_string; | |
1811 | kex->server_version_string=server_version_string; | |
1812 | kex->load_host_key=&get_hostkey_by_type; | |
1813 | kex->host_key_index=&get_hostkey_index; | |
1814 | ||
1815 | xxx_kex = kex; | |
1816 | ||
1817 | dispatch_run(DISPATCH_BLOCK, &kex->done, kex); | |
1818 | ||
1819 | session_id2 = kex->session_id; | |
1820 | session_id2_len = kex->session_id_len; | |
1821 | ||
1822 | #ifdef DEBUG_KEXDH | |
1823 | /* send 1st encrypted/maced/compressed message */ | |
1824 | packet_start(SSH2_MSG_IGNORE); | |
1825 | packet_put_cstring("markus"); | |
1826 | packet_send(); | |
1827 | packet_write_wait(); | |
1828 | #endif | |
1829 | debug("KEX done"); | |
1830 | } |