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1 | /* $OpenBSD: sshd.c,v 1.351 2007/05/22 10:18:52 djm Exp $ */ | |
2 | /* | |
3 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
4 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
5 | * All rights reserved | |
6 | * This program is the ssh daemon. It listens for connections from clients, | |
7 | * and performs authentication, executes use commands or shell, and forwards | |
8 | * information to/from the application to the user client over an encrypted | |
9 | * connection. This can also handle forwarding of X11, TCP/IP, and | |
10 | * authentication agent connections. | |
11 | * | |
12 | * As far as I am concerned, the code I have written for this software | |
13 | * can be used freely for any purpose. Any derived versions of this | |
14 | * software must be clearly marked as such, and if the derived work is | |
15 | * incompatible with the protocol description in the RFC file, it must be | |
16 | * called by a name other than "ssh" or "Secure Shell". | |
17 | * | |
18 | * SSH2 implementation: | |
19 | * Privilege Separation: | |
20 | * | |
21 | * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. | |
22 | * Copyright (c) 2002 Niels Provos. All rights reserved. | |
23 | * | |
24 | * Redistribution and use in source and binary forms, with or without | |
25 | * modification, are permitted provided that the following conditions | |
26 | * are met: | |
27 | * 1. Redistributions of source code must retain the above copyright | |
28 | * notice, this list of conditions and the following disclaimer. | |
29 | * 2. Redistributions in binary form must reproduce the above copyright | |
30 | * notice, this list of conditions and the following disclaimer in the | |
31 | * documentation and/or other materials provided with the distribution. | |
32 | * | |
33 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
34 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
35 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
36 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
37 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
38 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
39 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
40 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
41 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
42 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
43 | */ | |
44 | ||
45 | #include "includes.h" | |
46 | ||
47 | #include <sys/types.h> | |
48 | #include <sys/ioctl.h> | |
49 | #include <sys/socket.h> | |
50 | #ifdef HAVE_SYS_STAT_H | |
51 | # include <sys/stat.h> | |
52 | #endif | |
53 | #ifdef HAVE_SYS_TIME_H | |
54 | # include <sys/time.h> | |
55 | #endif | |
56 | #include "openbsd-compat/sys-tree.h" | |
57 | #include <sys/wait.h> | |
58 | ||
59 | #include <errno.h> | |
60 | #include <fcntl.h> | |
61 | #include <netdb.h> | |
62 | #ifdef HAVE_PATHS_H | |
63 | #include <paths.h> | |
64 | #endif | |
65 | #include <grp.h> | |
66 | #include <pwd.h> | |
67 | #include <signal.h> | |
68 | #include <stdarg.h> | |
69 | #include <stdio.h> | |
70 | #include <stdlib.h> | |
71 | #include <string.h> | |
72 | #include <unistd.h> | |
73 | ||
74 | #include <openssl/dh.h> | |
75 | #include <openssl/bn.h> | |
76 | #include <openssl/md5.h> | |
77 | #include <openssl/rand.h> | |
78 | #ifdef HAVE_SECUREWARE | |
79 | #include <sys/security.h> | |
80 | #include <prot.h> | |
81 | #endif | |
82 | ||
83 | #include "xmalloc.h" | |
84 | #include "ssh.h" | |
85 | #include "ssh1.h" | |
86 | #include "ssh2.h" | |
87 | #include "rsa.h" | |
88 | #include "sshpty.h" | |
89 | #include "packet.h" | |
90 | #include "log.h" | |
91 | #include "buffer.h" | |
92 | #include "servconf.h" | |
93 | #include "uidswap.h" | |
94 | #include "compat.h" | |
95 | #include "cipher.h" | |
96 | #include "key.h" | |
97 | #include "kex.h" | |
98 | #include "dh.h" | |
99 | #include "myproposal.h" | |
100 | #include "authfile.h" | |
101 | #include "pathnames.h" | |
102 | #include "atomicio.h" | |
103 | #include "canohost.h" | |
104 | #include "hostfile.h" | |
105 | #include "auth.h" | |
106 | #include "misc.h" | |
107 | #include "msg.h" | |
108 | #include "dispatch.h" | |
109 | #include "channels.h" | |
110 | #include "session.h" | |
111 | #include "monitor_mm.h" | |
112 | #include "monitor.h" | |
113 | #ifdef GSSAPI | |
114 | #include "ssh-gss.h" | |
115 | #endif | |
116 | #include "monitor_wrap.h" | |
117 | #include "monitor_fdpass.h" | |
118 | #include "version.h" | |
119 | ||
120 | #ifdef LIBWRAP | |
121 | #include <tcpd.h> | |
122 | #include <syslog.h> | |
123 | int allow_severity = LOG_INFO; | |
124 | int deny_severity = LOG_WARNING; | |
125 | #endif /* LIBWRAP */ | |
126 | ||
127 | #ifndef O_NOCTTY | |
128 | #define O_NOCTTY 0 | |
129 | #endif | |
130 | ||
131 | /* Re-exec fds */ | |
132 | #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) | |
133 | #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) | |
134 | #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) | |
135 | #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) | |
136 | ||
137 | extern char *__progname; | |
138 | ||
139 | /* Server configuration options. */ | |
140 | ServerOptions options; | |
141 | ||
142 | /* Name of the server configuration file. */ | |
143 | char *config_file_name = _PATH_SERVER_CONFIG_FILE; | |
144 | ||
145 | /* | |
146 | * Debug mode flag. This can be set on the command line. If debug | |
147 | * mode is enabled, extra debugging output will be sent to the system | |
148 | * log, the daemon will not go to background, and will exit after processing | |
149 | * the first connection. | |
150 | */ | |
151 | int debug_flag = 0; | |
152 | ||
153 | /* Flag indicating that the daemon should only test the configuration and keys. */ | |
154 | int test_flag = 0; | |
155 | ||
156 | /* Flag indicating that the daemon is being started from inetd. */ | |
157 | int inetd_flag = 0; | |
158 | ||
159 | /* Flag indicating that sshd should not detach and become a daemon. */ | |
160 | int no_daemon_flag = 0; | |
161 | ||
162 | /* debug goes to stderr unless inetd_flag is set */ | |
163 | int log_stderr = 0; | |
164 | ||
165 | /* Saved arguments to main(). */ | |
166 | char **saved_argv; | |
167 | int saved_argc; | |
168 | ||
169 | /* re-exec */ | |
170 | int rexeced_flag = 0; | |
171 | int rexec_flag = 1; | |
172 | int rexec_argc = 0; | |
173 | char **rexec_argv; | |
174 | ||
175 | /* | |
176 | * The sockets that the server is listening; this is used in the SIGHUP | |
177 | * signal handler. | |
178 | */ | |
179 | #define MAX_LISTEN_SOCKS 16 | |
180 | int listen_socks[MAX_LISTEN_SOCKS]; | |
181 | int num_listen_socks = 0; | |
182 | ||
183 | /* | |
184 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
185 | * sshd will skip the version-number exchange | |
186 | */ | |
187 | char *client_version_string = NULL; | |
188 | char *server_version_string = NULL; | |
189 | ||
190 | /* for rekeying XXX fixme */ | |
191 | Kex *xxx_kex; | |
192 | ||
193 | /* | |
194 | * Any really sensitive data in the application is contained in this | |
195 | * structure. The idea is that this structure could be locked into memory so | |
196 | * that the pages do not get written into swap. However, there are some | |
197 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
198 | * have access to the internals of them, and locking just the structure is | |
199 | * not very useful. Currently, memory locking is not implemented. | |
200 | */ | |
201 | struct { | |
202 | Key *server_key; /* ephemeral server key */ | |
203 | Key *ssh1_host_key; /* ssh1 host key */ | |
204 | Key **host_keys; /* all private host keys */ | |
205 | int have_ssh1_key; | |
206 | int have_ssh2_key; | |
207 | u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; | |
208 | } sensitive_data; | |
209 | ||
210 | /* | |
211 | * Flag indicating whether the RSA server key needs to be regenerated. | |
212 | * Is set in the SIGALRM handler and cleared when the key is regenerated. | |
213 | */ | |
214 | static volatile sig_atomic_t key_do_regen = 0; | |
215 | ||
216 | /* This is set to true when a signal is received. */ | |
217 | static volatile sig_atomic_t received_sighup = 0; | |
218 | static volatile sig_atomic_t received_sigterm = 0; | |
219 | ||
220 | /* session identifier, used by RSA-auth */ | |
221 | u_char session_id[16]; | |
222 | ||
223 | /* same for ssh2 */ | |
224 | u_char *session_id2 = NULL; | |
225 | u_int session_id2_len = 0; | |
226 | ||
227 | /* record remote hostname or ip */ | |
228 | u_int utmp_len = MAXHOSTNAMELEN; | |
229 | ||
230 | /* options.max_startup sized array of fd ints */ | |
231 | int *startup_pipes = NULL; | |
232 | int startup_pipe; /* in child */ | |
233 | ||
234 | /* variables used for privilege separation */ | |
235 | int use_privsep = -1; | |
236 | struct monitor *pmonitor = NULL; | |
237 | ||
238 | /* global authentication context */ | |
239 | Authctxt *the_authctxt = NULL; | |
240 | ||
241 | /* sshd_config buffer */ | |
242 | Buffer cfg; | |
243 | ||
244 | /* message to be displayed after login */ | |
245 | Buffer loginmsg; | |
246 | ||
247 | /* Unprivileged user */ | |
248 | struct passwd *privsep_pw = NULL; | |
249 | ||
250 | /* Prototypes for various functions defined later in this file. */ | |
251 | void destroy_sensitive_data(void); | |
252 | void demote_sensitive_data(void); | |
253 | ||
254 | static void do_ssh1_kex(void); | |
255 | static void do_ssh2_kex(void); | |
256 | ||
257 | /* | |
258 | * Close all listening sockets | |
259 | */ | |
260 | static void | |
261 | close_listen_socks(void) | |
262 | { | |
263 | int i; | |
264 | ||
265 | for (i = 0; i < num_listen_socks; i++) | |
266 | close(listen_socks[i]); | |
267 | num_listen_socks = -1; | |
268 | } | |
269 | ||
270 | static void | |
271 | close_startup_pipes(void) | |
272 | { | |
273 | int i; | |
274 | ||
275 | if (startup_pipes) | |
276 | for (i = 0; i < options.max_startups; i++) | |
277 | if (startup_pipes[i] != -1) | |
278 | close(startup_pipes[i]); | |
279 | } | |
280 | ||
281 | /* | |
282 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
283 | * the effect is to reread the configuration file (and to regenerate | |
284 | * the server key). | |
285 | */ | |
286 | ||
287 | /*ARGSUSED*/ | |
288 | static void | |
289 | sighup_handler(int sig) | |
290 | { | |
291 | int save_errno = errno; | |
292 | ||
293 | received_sighup = 1; | |
294 | signal(SIGHUP, sighup_handler); | |
295 | errno = save_errno; | |
296 | } | |
297 | ||
298 | /* | |
299 | * Called from the main program after receiving SIGHUP. | |
300 | * Restarts the server. | |
301 | */ | |
302 | static void | |
303 | sighup_restart(void) | |
304 | { | |
305 | logit("Received SIGHUP; restarting."); | |
306 | close_listen_socks(); | |
307 | close_startup_pipes(); | |
308 | alarm(0); /* alarm timer persists across exec */ | |
309 | execv(saved_argv[0], saved_argv); | |
310 | logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], | |
311 | strerror(errno)); | |
312 | exit(1); | |
313 | } | |
314 | ||
315 | /* | |
316 | * Generic signal handler for terminating signals in the master daemon. | |
317 | */ | |
318 | /*ARGSUSED*/ | |
319 | static void | |
320 | sigterm_handler(int sig) | |
321 | { | |
322 | received_sigterm = sig; | |
323 | } | |
324 | ||
325 | /* | |
326 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
327 | * reap any zombies left by exited children. | |
328 | */ | |
329 | /*ARGSUSED*/ | |
330 | static void | |
331 | main_sigchld_handler(int sig) | |
332 | { | |
333 | int save_errno = errno; | |
334 | pid_t pid; | |
335 | int status; | |
336 | ||
337 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || | |
338 | (pid < 0 && errno == EINTR)) | |
339 | ; | |
340 | ||
341 | signal(SIGCHLD, main_sigchld_handler); | |
342 | errno = save_errno; | |
343 | } | |
344 | ||
345 | /* | |
346 | * Signal handler for the alarm after the login grace period has expired. | |
347 | */ | |
348 | /*ARGSUSED*/ | |
349 | static void | |
350 | grace_alarm_handler(int sig) | |
351 | { | |
352 | if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) | |
353 | kill(pmonitor->m_pid, SIGALRM); | |
354 | ||
355 | /* Log error and exit. */ | |
356 | sigdie("Timeout before authentication for %s", get_remote_ipaddr()); | |
357 | } | |
358 | ||
359 | /* | |
360 | * Signal handler for the key regeneration alarm. Note that this | |
361 | * alarm only occurs in the daemon waiting for connections, and it does not | |
362 | * do anything with the private key or random state before forking. | |
363 | * Thus there should be no concurrency control/asynchronous execution | |
364 | * problems. | |
365 | */ | |
366 | static void | |
367 | generate_ephemeral_server_key(void) | |
368 | { | |
369 | u_int32_t rnd = 0; | |
370 | int i; | |
371 | ||
372 | verbose("Generating %s%d bit RSA key.", | |
373 | sensitive_data.server_key ? "new " : "", options.server_key_bits); | |
374 | if (sensitive_data.server_key != NULL) | |
375 | key_free(sensitive_data.server_key); | |
376 | sensitive_data.server_key = key_generate(KEY_RSA1, | |
377 | options.server_key_bits); | |
378 | verbose("RSA key generation complete."); | |
379 | ||
380 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
381 | if (i % 4 == 0) | |
382 | rnd = arc4random(); | |
383 | sensitive_data.ssh1_cookie[i] = rnd & 0xff; | |
384 | rnd >>= 8; | |
385 | } | |
386 | arc4random_stir(); | |
387 | } | |
388 | ||
389 | /*ARGSUSED*/ | |
390 | static void | |
391 | key_regeneration_alarm(int sig) | |
392 | { | |
393 | int save_errno = errno; | |
394 | ||
395 | signal(SIGALRM, SIG_DFL); | |
396 | errno = save_errno; | |
397 | key_do_regen = 1; | |
398 | } | |
399 | ||
400 | static void | |
401 | sshd_exchange_identification(int sock_in, int sock_out) | |
402 | { | |
403 | u_int i; | |
404 | int mismatch; | |
405 | int remote_major, remote_minor; | |
406 | int major, minor; | |
407 | char *s; | |
408 | char buf[256]; /* Must not be larger than remote_version. */ | |
409 | char remote_version[256]; /* Must be at least as big as buf. */ | |
410 | ||
411 | if ((options.protocol & SSH_PROTO_1) && | |
412 | (options.protocol & SSH_PROTO_2)) { | |
413 | major = PROTOCOL_MAJOR_1; | |
414 | minor = 99; | |
415 | } else if (options.protocol & SSH_PROTO_2) { | |
416 | major = PROTOCOL_MAJOR_2; | |
417 | minor = PROTOCOL_MINOR_2; | |
418 | } else { | |
419 | major = PROTOCOL_MAJOR_1; | |
420 | minor = PROTOCOL_MINOR_1; | |
421 | } | |
422 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
423 | server_version_string = xstrdup(buf); | |
424 | ||
425 | /* Send our protocol version identification. */ | |
426 | if (atomicio(vwrite, sock_out, server_version_string, | |
427 | strlen(server_version_string)) | |
428 | != strlen(server_version_string)) { | |
429 | logit("Could not write ident string to %s", get_remote_ipaddr()); | |
430 | cleanup_exit(255); | |
431 | } | |
432 | ||
433 | /* Read other sides version identification. */ | |
434 | memset(buf, 0, sizeof(buf)); | |
435 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
436 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { | |
437 | logit("Did not receive identification string from %s", | |
438 | get_remote_ipaddr()); | |
439 | cleanup_exit(255); | |
440 | } | |
441 | if (buf[i] == '\r') { | |
442 | buf[i] = 0; | |
443 | /* Kludge for F-Secure Macintosh < 1.0.2 */ | |
444 | if (i == 12 && | |
445 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
446 | break; | |
447 | continue; | |
448 | } | |
449 | if (buf[i] == '\n') { | |
450 | buf[i] = 0; | |
451 | break; | |
452 | } | |
453 | } | |
454 | buf[sizeof(buf) - 1] = 0; | |
455 | client_version_string = xstrdup(buf); | |
456 | ||
457 | /* | |
458 | * Check that the versions match. In future this might accept | |
459 | * several versions and set appropriate flags to handle them. | |
460 | */ | |
461 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
462 | &remote_major, &remote_minor, remote_version) != 3) { | |
463 | s = "Protocol mismatch.\n"; | |
464 | (void) atomicio(vwrite, sock_out, s, strlen(s)); | |
465 | close(sock_in); | |
466 | close(sock_out); | |
467 | logit("Bad protocol version identification '%.100s' from %s", | |
468 | client_version_string, get_remote_ipaddr()); | |
469 | cleanup_exit(255); | |
470 | } | |
471 | debug("Client protocol version %d.%d; client software version %.100s", | |
472 | remote_major, remote_minor, remote_version); | |
473 | ||
474 | compat_datafellows(remote_version); | |
475 | ||
476 | if (datafellows & SSH_BUG_PROBE) { | |
477 | logit("probed from %s with %s. Don't panic.", | |
478 | get_remote_ipaddr(), client_version_string); | |
479 | cleanup_exit(255); | |
480 | } | |
481 | ||
482 | if (datafellows & SSH_BUG_SCANNER) { | |
483 | logit("scanned from %s with %s. Don't panic.", | |
484 | get_remote_ipaddr(), client_version_string); | |
485 | cleanup_exit(255); | |
486 | } | |
487 | ||
488 | mismatch = 0; | |
489 | switch (remote_major) { | |
490 | case 1: | |
491 | if (remote_minor == 99) { | |
492 | if (options.protocol & SSH_PROTO_2) | |
493 | enable_compat20(); | |
494 | else | |
495 | mismatch = 1; | |
496 | break; | |
497 | } | |
498 | if (!(options.protocol & SSH_PROTO_1)) { | |
499 | mismatch = 1; | |
500 | break; | |
501 | } | |
502 | if (remote_minor < 3) { | |
503 | packet_disconnect("Your ssh version is too old and " | |
504 | "is no longer supported. Please install a newer version."); | |
505 | } else if (remote_minor == 3) { | |
506 | /* note that this disables agent-forwarding */ | |
507 | enable_compat13(); | |
508 | } | |
509 | break; | |
510 | case 2: | |
511 | if (options.protocol & SSH_PROTO_2) { | |
512 | enable_compat20(); | |
513 | break; | |
514 | } | |
515 | /* FALLTHROUGH */ | |
516 | default: | |
517 | mismatch = 1; | |
518 | break; | |
519 | } | |
520 | chop(server_version_string); | |
521 | debug("Local version string %.200s", server_version_string); | |
522 | ||
523 | if (mismatch) { | |
524 | s = "Protocol major versions differ.\n"; | |
525 | (void) atomicio(vwrite, sock_out, s, strlen(s)); | |
526 | close(sock_in); | |
527 | close(sock_out); | |
528 | logit("Protocol major versions differ for %s: %.200s vs. %.200s", | |
529 | get_remote_ipaddr(), | |
530 | server_version_string, client_version_string); | |
531 | cleanup_exit(255); | |
532 | } | |
533 | } | |
534 | ||
535 | /* Destroy the host and server keys. They will no longer be needed. */ | |
536 | void | |
537 | destroy_sensitive_data(void) | |
538 | { | |
539 | int i; | |
540 | ||
541 | if (sensitive_data.server_key) { | |
542 | key_free(sensitive_data.server_key); | |
543 | sensitive_data.server_key = NULL; | |
544 | } | |
545 | for (i = 0; i < options.num_host_key_files; i++) { | |
546 | if (sensitive_data.host_keys[i]) { | |
547 | key_free(sensitive_data.host_keys[i]); | |
548 | sensitive_data.host_keys[i] = NULL; | |
549 | } | |
550 | } | |
551 | sensitive_data.ssh1_host_key = NULL; | |
552 | memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); | |
553 | } | |
554 | ||
555 | /* Demote private to public keys for network child */ | |
556 | void | |
557 | demote_sensitive_data(void) | |
558 | { | |
559 | Key *tmp; | |
560 | int i; | |
561 | ||
562 | if (sensitive_data.server_key) { | |
563 | tmp = key_demote(sensitive_data.server_key); | |
564 | key_free(sensitive_data.server_key); | |
565 | sensitive_data.server_key = tmp; | |
566 | } | |
567 | ||
568 | for (i = 0; i < options.num_host_key_files; i++) { | |
569 | if (sensitive_data.host_keys[i]) { | |
570 | tmp = key_demote(sensitive_data.host_keys[i]); | |
571 | key_free(sensitive_data.host_keys[i]); | |
572 | sensitive_data.host_keys[i] = tmp; | |
573 | if (tmp->type == KEY_RSA1) | |
574 | sensitive_data.ssh1_host_key = tmp; | |
575 | } | |
576 | } | |
577 | ||
578 | /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ | |
579 | } | |
580 | ||
581 | static void | |
582 | privsep_preauth_child(void) | |
583 | { | |
584 | u_int32_t rnd[256]; | |
585 | gid_t gidset[1]; | |
586 | int i; | |
587 | ||
588 | /* Enable challenge-response authentication for privilege separation */ | |
589 | privsep_challenge_enable(); | |
590 | ||
591 | for (i = 0; i < 256; i++) | |
592 | rnd[i] = arc4random(); | |
593 | RAND_seed(rnd, sizeof(rnd)); | |
594 | ||
595 | /* Demote the private keys to public keys. */ | |
596 | demote_sensitive_data(); | |
597 | ||
598 | /* Change our root directory */ | |
599 | if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) | |
600 | fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, | |
601 | strerror(errno)); | |
602 | if (chdir("/") == -1) | |
603 | fatal("chdir(\"/\"): %s", strerror(errno)); | |
604 | ||
605 | /* Drop our privileges */ | |
606 | debug3("privsep user:group %u:%u", (u_int)privsep_pw->pw_uid, | |
607 | (u_int)privsep_pw->pw_gid); | |
608 | #if 0 | |
609 | /* XXX not ready, too heavy after chroot */ | |
610 | do_setusercontext(privsep_pw); | |
611 | #else | |
612 | gidset[0] = privsep_pw->pw_gid; | |
613 | if (setgroups(1, gidset) < 0) | |
614 | fatal("setgroups: %.100s", strerror(errno)); | |
615 | permanently_set_uid(privsep_pw); | |
616 | #endif | |
617 | } | |
618 | ||
619 | static int | |
620 | privsep_preauth(Authctxt *authctxt) | |
621 | { | |
622 | int status; | |
623 | pid_t pid; | |
624 | ||
625 | /* Set up unprivileged child process to deal with network data */ | |
626 | pmonitor = monitor_init(); | |
627 | /* Store a pointer to the kex for later rekeying */ | |
628 | pmonitor->m_pkex = &xxx_kex; | |
629 | ||
630 | pid = fork(); | |
631 | if (pid == -1) { | |
632 | fatal("fork of unprivileged child failed"); | |
633 | } else if (pid != 0) { | |
634 | debug2("Network child is on pid %ld", (long)pid); | |
635 | ||
636 | close(pmonitor->m_recvfd); | |
637 | pmonitor->m_pid = pid; | |
638 | monitor_child_preauth(authctxt, pmonitor); | |
639 | close(pmonitor->m_sendfd); | |
640 | ||
641 | /* Sync memory */ | |
642 | monitor_sync(pmonitor); | |
643 | ||
644 | /* Wait for the child's exit status */ | |
645 | while (waitpid(pid, &status, 0) < 0) | |
646 | if (errno != EINTR) | |
647 | break; | |
648 | return (1); | |
649 | } else { | |
650 | /* child */ | |
651 | ||
652 | close(pmonitor->m_sendfd); | |
653 | ||
654 | /* Demote the child */ | |
655 | if (getuid() == 0 || geteuid() == 0) | |
656 | privsep_preauth_child(); | |
657 | setproctitle("%s", "[net]"); | |
658 | } | |
659 | return (0); | |
660 | } | |
661 | ||
662 | static void | |
663 | privsep_postauth(Authctxt *authctxt) | |
664 | { | |
665 | #ifdef DISABLE_FD_PASSING | |
666 | if (1) { | |
667 | #else | |
668 | if (authctxt->pw->pw_uid == 0 || options.use_login) { | |
669 | #endif | |
670 | /* File descriptor passing is broken or root login */ | |
671 | use_privsep = 0; | |
672 | goto skip; | |
673 | } | |
674 | ||
675 | /* New socket pair */ | |
676 | monitor_reinit(pmonitor); | |
677 | ||
678 | pmonitor->m_pid = fork(); | |
679 | if (pmonitor->m_pid == -1) | |
680 | fatal("fork of unprivileged child failed"); | |
681 | else if (pmonitor->m_pid != 0) { | |
682 | debug2("User child is on pid %ld", (long)pmonitor->m_pid); | |
683 | close(pmonitor->m_recvfd); | |
684 | buffer_clear(&loginmsg); | |
685 | monitor_child_postauth(pmonitor); | |
686 | ||
687 | /* NEVERREACHED */ | |
688 | exit(0); | |
689 | } | |
690 | ||
691 | close(pmonitor->m_sendfd); | |
692 | ||
693 | /* Demote the private keys to public keys. */ | |
694 | demote_sensitive_data(); | |
695 | ||
696 | /* Drop privileges */ | |
697 | do_setusercontext(authctxt->pw); | |
698 | ||
699 | skip: | |
700 | /* It is safe now to apply the key state */ | |
701 | monitor_apply_keystate(pmonitor); | |
702 | ||
703 | /* | |
704 | * Tell the packet layer that authentication was successful, since | |
705 | * this information is not part of the key state. | |
706 | */ | |
707 | packet_set_authenticated(); | |
708 | } | |
709 | ||
710 | static char * | |
711 | list_hostkey_types(void) | |
712 | { | |
713 | Buffer b; | |
714 | const char *p; | |
715 | char *ret; | |
716 | int i; | |
717 | ||
718 | buffer_init(&b); | |
719 | for (i = 0; i < options.num_host_key_files; i++) { | |
720 | Key *key = sensitive_data.host_keys[i]; | |
721 | if (key == NULL) | |
722 | continue; | |
723 | switch (key->type) { | |
724 | case KEY_RSA: | |
725 | case KEY_DSA: | |
726 | if (buffer_len(&b) > 0) | |
727 | buffer_append(&b, ",", 1); | |
728 | p = key_ssh_name(key); | |
729 | buffer_append(&b, p, strlen(p)); | |
730 | break; | |
731 | } | |
732 | } | |
733 | buffer_append(&b, "\0", 1); | |
734 | ret = xstrdup(buffer_ptr(&b)); | |
735 | buffer_free(&b); | |
736 | debug("list_hostkey_types: %s", ret); | |
737 | return ret; | |
738 | } | |
739 | ||
740 | Key * | |
741 | get_hostkey_by_type(int type) | |
742 | { | |
743 | int i; | |
744 | ||
745 | for (i = 0; i < options.num_host_key_files; i++) { | |
746 | Key *key = sensitive_data.host_keys[i]; | |
747 | if (key != NULL && key->type == type) | |
748 | return key; | |
749 | } | |
750 | return NULL; | |
751 | } | |
752 | ||
753 | Key * | |
754 | get_hostkey_by_index(int ind) | |
755 | { | |
756 | if (ind < 0 || ind >= options.num_host_key_files) | |
757 | return (NULL); | |
758 | return (sensitive_data.host_keys[ind]); | |
759 | } | |
760 | ||
761 | int | |
762 | get_hostkey_index(Key *key) | |
763 | { | |
764 | int i; | |
765 | ||
766 | for (i = 0; i < options.num_host_key_files; i++) { | |
767 | if (key == sensitive_data.host_keys[i]) | |
768 | return (i); | |
769 | } | |
770 | return (-1); | |
771 | } | |
772 | ||
773 | /* | |
774 | * returns 1 if connection should be dropped, 0 otherwise. | |
775 | * dropping starts at connection #max_startups_begin with a probability | |
776 | * of (max_startups_rate/100). the probability increases linearly until | |
777 | * all connections are dropped for startups > max_startups | |
778 | */ | |
779 | static int | |
780 | drop_connection(int startups) | |
781 | { | |
782 | int p, r; | |
783 | ||
784 | if (startups < options.max_startups_begin) | |
785 | return 0; | |
786 | if (startups >= options.max_startups) | |
787 | return 1; | |
788 | if (options.max_startups_rate == 100) | |
789 | return 1; | |
790 | ||
791 | p = 100 - options.max_startups_rate; | |
792 | p *= startups - options.max_startups_begin; | |
793 | p /= options.max_startups - options.max_startups_begin; | |
794 | p += options.max_startups_rate; | |
795 | r = arc4random() % 100; | |
796 | ||
797 | debug("drop_connection: p %d, r %d", p, r); | |
798 | return (r < p) ? 1 : 0; | |
799 | } | |
800 | ||
801 | static void | |
802 | usage(void) | |
803 | { | |
804 | fprintf(stderr, "%s, %s\n", | |
805 | SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); | |
806 | fprintf(stderr, | |
807 | "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n" | |
808 | " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n" | |
809 | ); | |
810 | exit(1); | |
811 | } | |
812 | ||
813 | static void | |
814 | send_rexec_state(int fd, Buffer *conf) | |
815 | { | |
816 | Buffer m; | |
817 | ||
818 | debug3("%s: entering fd = %d config len %d", __func__, fd, | |
819 | buffer_len(conf)); | |
820 | ||
821 | /* | |
822 | * Protocol from reexec master to child: | |
823 | * string configuration | |
824 | * u_int ephemeral_key_follows | |
825 | * bignum e (only if ephemeral_key_follows == 1) | |
826 | * bignum n " | |
827 | * bignum d " | |
828 | * bignum iqmp " | |
829 | * bignum p " | |
830 | * bignum q " | |
831 | * string rngseed (only if OpenSSL is not self-seeded) | |
832 | */ | |
833 | buffer_init(&m); | |
834 | buffer_put_cstring(&m, buffer_ptr(conf)); | |
835 | ||
836 | if (sensitive_data.server_key != NULL && | |
837 | sensitive_data.server_key->type == KEY_RSA1) { | |
838 | buffer_put_int(&m, 1); | |
839 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); | |
840 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); | |
841 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); | |
842 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); | |
843 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); | |
844 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); | |
845 | } else | |
846 | buffer_put_int(&m, 0); | |
847 | ||
848 | #ifndef OPENSSL_PRNG_ONLY | |
849 | rexec_send_rng_seed(&m); | |
850 | #endif | |
851 | ||
852 | if (ssh_msg_send(fd, 0, &m) == -1) | |
853 | fatal("%s: ssh_msg_send failed", __func__); | |
854 | ||
855 | buffer_free(&m); | |
856 | ||
857 | debug3("%s: done", __func__); | |
858 | } | |
859 | ||
860 | static void | |
861 | recv_rexec_state(int fd, Buffer *conf) | |
862 | { | |
863 | Buffer m; | |
864 | char *cp; | |
865 | u_int len; | |
866 | ||
867 | debug3("%s: entering fd = %d", __func__, fd); | |
868 | ||
869 | buffer_init(&m); | |
870 | ||
871 | if (ssh_msg_recv(fd, &m) == -1) | |
872 | fatal("%s: ssh_msg_recv failed", __func__); | |
873 | if (buffer_get_char(&m) != 0) | |
874 | fatal("%s: rexec version mismatch", __func__); | |
875 | ||
876 | cp = buffer_get_string(&m, &len); | |
877 | if (conf != NULL) | |
878 | buffer_append(conf, cp, len + 1); | |
879 | xfree(cp); | |
880 | ||
881 | if (buffer_get_int(&m)) { | |
882 | if (sensitive_data.server_key != NULL) | |
883 | key_free(sensitive_data.server_key); | |
884 | sensitive_data.server_key = key_new_private(KEY_RSA1); | |
885 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); | |
886 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); | |
887 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); | |
888 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); | |
889 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); | |
890 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); | |
891 | rsa_generate_additional_parameters( | |
892 | sensitive_data.server_key->rsa); | |
893 | } | |
894 | ||
895 | #ifndef OPENSSL_PRNG_ONLY | |
896 | rexec_recv_rng_seed(&m); | |
897 | #endif | |
898 | ||
899 | buffer_free(&m); | |
900 | ||
901 | debug3("%s: done", __func__); | |
902 | } | |
903 | ||
904 | /* Accept a connection from inetd */ | |
905 | static void | |
906 | server_accept_inetd(int *sock_in, int *sock_out) | |
907 | { | |
908 | int fd; | |
909 | ||
910 | startup_pipe = -1; | |
911 | if (rexeced_flag) { | |
912 | close(REEXEC_CONFIG_PASS_FD); | |
913 | *sock_in = *sock_out = dup(STDIN_FILENO); | |
914 | if (!debug_flag) { | |
915 | startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); | |
916 | close(REEXEC_STARTUP_PIPE_FD); | |
917 | } | |
918 | } else { | |
919 | *sock_in = dup(STDIN_FILENO); | |
920 | *sock_out = dup(STDOUT_FILENO); | |
921 | } | |
922 | /* | |
923 | * We intentionally do not close the descriptors 0, 1, and 2 | |
924 | * as our code for setting the descriptors won't work if | |
925 | * ttyfd happens to be one of those. | |
926 | */ | |
927 | if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { | |
928 | dup2(fd, STDIN_FILENO); | |
929 | dup2(fd, STDOUT_FILENO); | |
930 | if (fd > STDOUT_FILENO) | |
931 | close(fd); | |
932 | } | |
933 | debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out); | |
934 | } | |
935 | ||
936 | /* | |
937 | * Listen for TCP connections | |
938 | */ | |
939 | static void | |
940 | server_listen(void) | |
941 | { | |
942 | int ret, listen_sock, on = 1; | |
943 | struct addrinfo *ai; | |
944 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
945 | ||
946 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { | |
947 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
948 | continue; | |
949 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
950 | fatal("Too many listen sockets. " | |
951 | "Enlarge MAX_LISTEN_SOCKS"); | |
952 | if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
953 | ntop, sizeof(ntop), strport, sizeof(strport), | |
954 | NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { | |
955 | error("getnameinfo failed: %.100s", | |
956 | (ret != EAI_SYSTEM) ? gai_strerror(ret) : | |
957 | strerror(errno)); | |
958 | continue; | |
959 | } | |
960 | /* Create socket for listening. */ | |
961 | listen_sock = socket(ai->ai_family, ai->ai_socktype, | |
962 | ai->ai_protocol); | |
963 | if (listen_sock < 0) { | |
964 | /* kernel may not support ipv6 */ | |
965 | verbose("socket: %.100s", strerror(errno)); | |
966 | continue; | |
967 | } | |
968 | if (set_nonblock(listen_sock) == -1) { | |
969 | close(listen_sock); | |
970 | continue; | |
971 | } | |
972 | /* | |
973 | * Set socket options. | |
974 | * Allow local port reuse in TIME_WAIT. | |
975 | */ | |
976 | if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, | |
977 | &on, sizeof(on)) == -1) | |
978 | error("setsockopt SO_REUSEADDR: %s", strerror(errno)); | |
979 | ||
980 | debug("Bind to port %s on %s.", strport, ntop); | |
981 | ||
982 | /* Bind the socket to the desired port. */ | |
983 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { | |
984 | error("Bind to port %s on %s failed: %.200s.", | |
985 | strport, ntop, strerror(errno)); | |
986 | close(listen_sock); | |
987 | continue; | |
988 | } | |
989 | listen_socks[num_listen_socks] = listen_sock; | |
990 | num_listen_socks++; | |
991 | ||
992 | /* Start listening on the port. */ | |
993 | if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) | |
994 | fatal("listen on [%s]:%s: %.100s", | |
995 | ntop, strport, strerror(errno)); | |
996 | logit("Server listening on %s port %s.", ntop, strport); | |
997 | } | |
998 | freeaddrinfo(options.listen_addrs); | |
999 | ||
1000 | if (!num_listen_socks) | |
1001 | fatal("Cannot bind any address."); | |
1002 | } | |
1003 | ||
1004 | /* | |
1005 | * The main TCP accept loop. Note that, for the non-debug case, returns | |
1006 | * from this function are in a forked subprocess. | |
1007 | */ | |
1008 | static void | |
1009 | server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s) | |
1010 | { | |
1011 | fd_set *fdset; | |
1012 | int i, j, ret, maxfd; | |
1013 | int key_used = 0, startups = 0; | |
1014 | int startup_p[2] = { -1 , -1 }; | |
1015 | struct sockaddr_storage from; | |
1016 | socklen_t fromlen; | |
1017 | pid_t pid; | |
1018 | ||
1019 | /* setup fd set for accept */ | |
1020 | fdset = NULL; | |
1021 | maxfd = 0; | |
1022 | for (i = 0; i < num_listen_socks; i++) | |
1023 | if (listen_socks[i] > maxfd) | |
1024 | maxfd = listen_socks[i]; | |
1025 | /* pipes connected to unauthenticated childs */ | |
1026 | startup_pipes = xcalloc(options.max_startups, sizeof(int)); | |
1027 | for (i = 0; i < options.max_startups; i++) | |
1028 | startup_pipes[i] = -1; | |
1029 | ||
1030 | /* | |
1031 | * Stay listening for connections until the system crashes or | |
1032 | * the daemon is killed with a signal. | |
1033 | */ | |
1034 | for (;;) { | |
1035 | if (received_sighup) | |
1036 | sighup_restart(); | |
1037 | if (fdset != NULL) | |
1038 | xfree(fdset); | |
1039 | fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS), | |
1040 | sizeof(fd_mask)); | |
1041 | ||
1042 | for (i = 0; i < num_listen_socks; i++) | |
1043 | FD_SET(listen_socks[i], fdset); | |
1044 | for (i = 0; i < options.max_startups; i++) | |
1045 | if (startup_pipes[i] != -1) | |
1046 | FD_SET(startup_pipes[i], fdset); | |
1047 | ||
1048 | /* Wait in select until there is a connection. */ | |
1049 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); | |
1050 | if (ret < 0 && errno != EINTR) | |
1051 | error("select: %.100s", strerror(errno)); | |
1052 | if (received_sigterm) { | |
1053 | logit("Received signal %d; terminating.", | |
1054 | (int) received_sigterm); | |
1055 | close_listen_socks(); | |
1056 | unlink(options.pid_file); | |
1057 | exit(255); | |
1058 | } | |
1059 | if (key_used && key_do_regen) { | |
1060 | generate_ephemeral_server_key(); | |
1061 | key_used = 0; | |
1062 | key_do_regen = 0; | |
1063 | } | |
1064 | if (ret < 0) | |
1065 | continue; | |
1066 | ||
1067 | for (i = 0; i < options.max_startups; i++) | |
1068 | if (startup_pipes[i] != -1 && | |
1069 | FD_ISSET(startup_pipes[i], fdset)) { | |
1070 | /* | |
1071 | * the read end of the pipe is ready | |
1072 | * if the child has closed the pipe | |
1073 | * after successful authentication | |
1074 | * or if the child has died | |
1075 | */ | |
1076 | close(startup_pipes[i]); | |
1077 | startup_pipes[i] = -1; | |
1078 | startups--; | |
1079 | } | |
1080 | for (i = 0; i < num_listen_socks; i++) { | |
1081 | if (!FD_ISSET(listen_socks[i], fdset)) | |
1082 | continue; | |
1083 | fromlen = sizeof(from); | |
1084 | *newsock = accept(listen_socks[i], | |
1085 | (struct sockaddr *)&from, &fromlen); | |
1086 | if (*newsock < 0) { | |
1087 | if (errno != EINTR && errno != EWOULDBLOCK) | |
1088 | error("accept: %.100s", strerror(errno)); | |
1089 | continue; | |
1090 | } | |
1091 | if (unset_nonblock(*newsock) == -1) { | |
1092 | close(*newsock); | |
1093 | continue; | |
1094 | } | |
1095 | if (drop_connection(startups) == 1) { | |
1096 | debug("drop connection #%d", startups); | |
1097 | close(*newsock); | |
1098 | continue; | |
1099 | } | |
1100 | if (pipe(startup_p) == -1) { | |
1101 | close(*newsock); | |
1102 | continue; | |
1103 | } | |
1104 | ||
1105 | if (rexec_flag && socketpair(AF_UNIX, | |
1106 | SOCK_STREAM, 0, config_s) == -1) { | |
1107 | error("reexec socketpair: %s", | |
1108 | strerror(errno)); | |
1109 | close(*newsock); | |
1110 | close(startup_p[0]); | |
1111 | close(startup_p[1]); | |
1112 | continue; | |
1113 | } | |
1114 | ||
1115 | for (j = 0; j < options.max_startups; j++) | |
1116 | if (startup_pipes[j] == -1) { | |
1117 | startup_pipes[j] = startup_p[0]; | |
1118 | if (maxfd < startup_p[0]) | |
1119 | maxfd = startup_p[0]; | |
1120 | startups++; | |
1121 | break; | |
1122 | } | |
1123 | ||
1124 | /* | |
1125 | * Got connection. Fork a child to handle it, unless | |
1126 | * we are in debugging mode. | |
1127 | */ | |
1128 | if (debug_flag) { | |
1129 | /* | |
1130 | * In debugging mode. Close the listening | |
1131 | * socket, and start processing the | |
1132 | * connection without forking. | |
1133 | */ | |
1134 | debug("Server will not fork when running in debugging mode."); | |
1135 | close_listen_socks(); | |
1136 | *sock_in = *newsock; | |
1137 | *sock_out = *newsock; | |
1138 | close(startup_p[0]); | |
1139 | close(startup_p[1]); | |
1140 | startup_pipe = -1; | |
1141 | pid = getpid(); | |
1142 | if (rexec_flag) { | |
1143 | send_rexec_state(config_s[0], | |
1144 | &cfg); | |
1145 | close(config_s[0]); | |
1146 | } | |
1147 | break; | |
1148 | } | |
1149 | ||
1150 | /* | |
1151 | * Normal production daemon. Fork, and have | |
1152 | * the child process the connection. The | |
1153 | * parent continues listening. | |
1154 | */ | |
1155 | platform_pre_fork(); | |
1156 | if ((pid = fork()) == 0) { | |
1157 | /* | |
1158 | * Child. Close the listening and | |
1159 | * max_startup sockets. Start using | |
1160 | * the accepted socket. Reinitialize | |
1161 | * logging (since our pid has changed). | |
1162 | * We break out of the loop to handle | |
1163 | * the connection. | |
1164 | */ | |
1165 | platform_post_fork_child(); | |
1166 | startup_pipe = startup_p[1]; | |
1167 | close_startup_pipes(); | |
1168 | close_listen_socks(); | |
1169 | *sock_in = *newsock; | |
1170 | *sock_out = *newsock; | |
1171 | log_init(__progname, | |
1172 | options.log_level, | |
1173 | options.log_facility, | |
1174 | log_stderr); | |
1175 | if (rexec_flag) | |
1176 | close(config_s[0]); | |
1177 | break; | |
1178 | } | |
1179 | ||
1180 | /* Parent. Stay in the loop. */ | |
1181 | platform_post_fork_parent(pid); | |
1182 | if (pid < 0) | |
1183 | error("fork: %.100s", strerror(errno)); | |
1184 | else | |
1185 | debug("Forked child %ld.", (long)pid); | |
1186 | ||
1187 | close(startup_p[1]); | |
1188 | ||
1189 | if (rexec_flag) { | |
1190 | send_rexec_state(config_s[0], &cfg); | |
1191 | close(config_s[0]); | |
1192 | close(config_s[1]); | |
1193 | } | |
1194 | ||
1195 | /* | |
1196 | * Mark that the key has been used (it | |
1197 | * was "given" to the child). | |
1198 | */ | |
1199 | if ((options.protocol & SSH_PROTO_1) && | |
1200 | key_used == 0) { | |
1201 | /* Schedule server key regeneration alarm. */ | |
1202 | signal(SIGALRM, key_regeneration_alarm); | |
1203 | alarm(options.key_regeneration_time); | |
1204 | key_used = 1; | |
1205 | } | |
1206 | ||
1207 | close(*newsock); | |
1208 | ||
1209 | /* | |
1210 | * Ensure that our random state differs | |
1211 | * from that of the child | |
1212 | */ | |
1213 | arc4random_stir(); | |
1214 | } | |
1215 | ||
1216 | /* child process check (or debug mode) */ | |
1217 | if (num_listen_socks < 0) | |
1218 | break; | |
1219 | } | |
1220 | } | |
1221 | ||
1222 | ||
1223 | /* | |
1224 | * Main program for the daemon. | |
1225 | */ | |
1226 | int | |
1227 | main(int ac, char **av) | |
1228 | { | |
1229 | extern char *optarg; | |
1230 | extern int optind; | |
1231 | int opt, i, on = 1; | |
1232 | int sock_in = -1, sock_out = -1, newsock = -1; | |
1233 | const char *remote_ip; | |
1234 | int remote_port; | |
1235 | char *line; | |
1236 | int config_s[2] = { -1 , -1 }; | |
1237 | Key *key; | |
1238 | Authctxt *authctxt; | |
1239 | ||
1240 | #ifdef HAVE_SECUREWARE | |
1241 | (void)set_auth_parameters(ac, av); | |
1242 | #endif | |
1243 | __progname = ssh_get_progname(av[0]); | |
1244 | init_rng(); | |
1245 | ||
1246 | /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ | |
1247 | saved_argc = ac; | |
1248 | rexec_argc = ac; | |
1249 | saved_argv = xcalloc(ac + 1, sizeof(*saved_argv)); | |
1250 | for (i = 0; i < ac; i++) | |
1251 | saved_argv[i] = xstrdup(av[i]); | |
1252 | saved_argv[i] = NULL; | |
1253 | ||
1254 | #ifndef HAVE_SETPROCTITLE | |
1255 | /* Prepare for later setproctitle emulation */ | |
1256 | compat_init_setproctitle(ac, av); | |
1257 | av = saved_argv; | |
1258 | #endif | |
1259 | ||
1260 | if (geteuid() == 0 && setgroups(0, NULL) == -1) | |
1261 | debug("setgroups(): %.200s", strerror(errno)); | |
1262 | ||
1263 | /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ | |
1264 | sanitise_stdfd(); | |
1265 | ||
1266 | /* Initialize configuration options to their default values. */ | |
1267 | initialize_server_options(&options); | |
1268 | ||
1269 | /* Parse command-line arguments. */ | |
1270 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) { | |
1271 | switch (opt) { | |
1272 | case '4': | |
1273 | options.address_family = AF_INET; | |
1274 | break; | |
1275 | case '6': | |
1276 | options.address_family = AF_INET6; | |
1277 | break; | |
1278 | case 'f': | |
1279 | config_file_name = optarg; | |
1280 | break; | |
1281 | case 'd': | |
1282 | if (debug_flag == 0) { | |
1283 | debug_flag = 1; | |
1284 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
1285 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) | |
1286 | options.log_level++; | |
1287 | break; | |
1288 | case 'D': | |
1289 | no_daemon_flag = 1; | |
1290 | break; | |
1291 | case 'e': | |
1292 | log_stderr = 1; | |
1293 | break; | |
1294 | case 'i': | |
1295 | inetd_flag = 1; | |
1296 | break; | |
1297 | case 'r': | |
1298 | rexec_flag = 0; | |
1299 | break; | |
1300 | case 'R': | |
1301 | rexeced_flag = 1; | |
1302 | inetd_flag = 1; | |
1303 | break; | |
1304 | case 'Q': | |
1305 | /* ignored */ | |
1306 | break; | |
1307 | case 'q': | |
1308 | options.log_level = SYSLOG_LEVEL_QUIET; | |
1309 | break; | |
1310 | case 'b': | |
1311 | options.server_key_bits = (int)strtonum(optarg, 256, | |
1312 | 32768, NULL); | |
1313 | break; | |
1314 | case 'p': | |
1315 | options.ports_from_cmdline = 1; | |
1316 | if (options.num_ports >= MAX_PORTS) { | |
1317 | fprintf(stderr, "too many ports.\n"); | |
1318 | exit(1); | |
1319 | } | |
1320 | options.ports[options.num_ports++] = a2port(optarg); | |
1321 | if (options.ports[options.num_ports-1] == 0) { | |
1322 | fprintf(stderr, "Bad port number.\n"); | |
1323 | exit(1); | |
1324 | } | |
1325 | break; | |
1326 | case 'g': | |
1327 | if ((options.login_grace_time = convtime(optarg)) == -1) { | |
1328 | fprintf(stderr, "Invalid login grace time.\n"); | |
1329 | exit(1); | |
1330 | } | |
1331 | break; | |
1332 | case 'k': | |
1333 | if ((options.key_regeneration_time = convtime(optarg)) == -1) { | |
1334 | fprintf(stderr, "Invalid key regeneration interval.\n"); | |
1335 | exit(1); | |
1336 | } | |
1337 | break; | |
1338 | case 'h': | |
1339 | if (options.num_host_key_files >= MAX_HOSTKEYS) { | |
1340 | fprintf(stderr, "too many host keys.\n"); | |
1341 | exit(1); | |
1342 | } | |
1343 | options.host_key_files[options.num_host_key_files++] = optarg; | |
1344 | break; | |
1345 | case 't': | |
1346 | test_flag = 1; | |
1347 | break; | |
1348 | case 'u': | |
1349 | utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL); | |
1350 | if (utmp_len > MAXHOSTNAMELEN) { | |
1351 | fprintf(stderr, "Invalid utmp length.\n"); | |
1352 | exit(1); | |
1353 | } | |
1354 | break; | |
1355 | case 'o': | |
1356 | line = xstrdup(optarg); | |
1357 | if (process_server_config_line(&options, line, | |
1358 | "command-line", 0, NULL, NULL, NULL, NULL) != 0) | |
1359 | exit(1); | |
1360 | xfree(line); | |
1361 | break; | |
1362 | case '?': | |
1363 | default: | |
1364 | usage(); | |
1365 | break; | |
1366 | } | |
1367 | } | |
1368 | if (rexeced_flag || inetd_flag) | |
1369 | rexec_flag = 0; | |
1370 | if (rexec_flag && (av[0] == NULL || *av[0] != '/')) | |
1371 | fatal("sshd re-exec requires execution with an absolute path"); | |
1372 | if (rexeced_flag) | |
1373 | closefrom(REEXEC_MIN_FREE_FD); | |
1374 | else | |
1375 | closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); | |
1376 | ||
1377 | SSLeay_add_all_algorithms(); | |
1378 | ||
1379 | /* | |
1380 | * Force logging to stderr until we have loaded the private host | |
1381 | * key (unless started from inetd) | |
1382 | */ | |
1383 | log_init(__progname, | |
1384 | options.log_level == SYSLOG_LEVEL_NOT_SET ? | |
1385 | SYSLOG_LEVEL_INFO : options.log_level, | |
1386 | options.log_facility == SYSLOG_FACILITY_NOT_SET ? | |
1387 | SYSLOG_FACILITY_AUTH : options.log_facility, | |
1388 | log_stderr || !inetd_flag); | |
1389 | ||
1390 | /* | |
1391 | * Unset KRB5CCNAME, otherwise the user's session may inherit it from | |
1392 | * root's environment | |
1393 | */ | |
1394 | if (getenv("KRB5CCNAME") != NULL) | |
1395 | unsetenv("KRB5CCNAME"); | |
1396 | ||
1397 | #ifdef _UNICOS | |
1398 | /* Cray can define user privs drop all privs now! | |
1399 | * Not needed on PRIV_SU systems! | |
1400 | */ | |
1401 | drop_cray_privs(); | |
1402 | #endif | |
1403 | ||
1404 | sensitive_data.server_key = NULL; | |
1405 | sensitive_data.ssh1_host_key = NULL; | |
1406 | sensitive_data.have_ssh1_key = 0; | |
1407 | sensitive_data.have_ssh2_key = 0; | |
1408 | ||
1409 | /* Fetch our configuration */ | |
1410 | buffer_init(&cfg); | |
1411 | if (rexeced_flag) | |
1412 | recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); | |
1413 | else | |
1414 | load_server_config(config_file_name, &cfg); | |
1415 | ||
1416 | parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name, | |
1417 | &cfg, NULL, NULL, NULL); | |
1418 | ||
1419 | seed_rng(); | |
1420 | ||
1421 | /* Fill in default values for those options not explicitly set. */ | |
1422 | fill_default_server_options(&options); | |
1423 | ||
1424 | /* challenge-response is implemented via keyboard interactive */ | |
1425 | if (options.challenge_response_authentication) | |
1426 | options.kbd_interactive_authentication = 1; | |
1427 | ||
1428 | /* set default channel AF */ | |
1429 | channel_set_af(options.address_family); | |
1430 | ||
1431 | /* Check that there are no remaining arguments. */ | |
1432 | if (optind < ac) { | |
1433 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
1434 | exit(1); | |
1435 | } | |
1436 | ||
1437 | debug("sshd version %.100s", SSH_RELEASE); | |
1438 | ||
1439 | /* Store privilege separation user for later use if required. */ | |
1440 | if ((privsep_pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) { | |
1441 | if (use_privsep || options.kerberos_authentication) | |
1442 | fatal("Privilege separation user %s does not exist", | |
1443 | SSH_PRIVSEP_USER); | |
1444 | } else { | |
1445 | memset(privsep_pw->pw_passwd, 0, strlen(privsep_pw->pw_passwd)); | |
1446 | privsep_pw = pwcopy(privsep_pw); | |
1447 | xfree(privsep_pw->pw_passwd); | |
1448 | privsep_pw->pw_passwd = xstrdup("*"); | |
1449 | } | |
1450 | endpwent(); | |
1451 | ||
1452 | /* load private host keys */ | |
1453 | sensitive_data.host_keys = xcalloc(options.num_host_key_files, | |
1454 | sizeof(Key *)); | |
1455 | for (i = 0; i < options.num_host_key_files; i++) | |
1456 | sensitive_data.host_keys[i] = NULL; | |
1457 | ||
1458 | for (i = 0; i < options.num_host_key_files; i++) { | |
1459 | key = key_load_private(options.host_key_files[i], "", NULL); | |
1460 | sensitive_data.host_keys[i] = key; | |
1461 | if (key == NULL) { | |
1462 | error("Could not load host key: %s", | |
1463 | options.host_key_files[i]); | |
1464 | sensitive_data.host_keys[i] = NULL; | |
1465 | continue; | |
1466 | } | |
1467 | switch (key->type) { | |
1468 | case KEY_RSA1: | |
1469 | sensitive_data.ssh1_host_key = key; | |
1470 | sensitive_data.have_ssh1_key = 1; | |
1471 | break; | |
1472 | case KEY_RSA: | |
1473 | case KEY_DSA: | |
1474 | sensitive_data.have_ssh2_key = 1; | |
1475 | break; | |
1476 | } | |
1477 | debug("private host key: #%d type %d %s", i, key->type, | |
1478 | key_type(key)); | |
1479 | } | |
1480 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
1481 | logit("Disabling protocol version 1. Could not load host key"); | |
1482 | options.protocol &= ~SSH_PROTO_1; | |
1483 | } | |
1484 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
1485 | logit("Disabling protocol version 2. Could not load host key"); | |
1486 | options.protocol &= ~SSH_PROTO_2; | |
1487 | } | |
1488 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { | |
1489 | logit("sshd: no hostkeys available -- exiting."); | |
1490 | exit(1); | |
1491 | } | |
1492 | ||
1493 | /* Check certain values for sanity. */ | |
1494 | if (options.protocol & SSH_PROTO_1) { | |
1495 | if (options.server_key_bits < 512 || | |
1496 | options.server_key_bits > 32768) { | |
1497 | fprintf(stderr, "Bad server key size.\n"); | |
1498 | exit(1); | |
1499 | } | |
1500 | /* | |
1501 | * Check that server and host key lengths differ sufficiently. This | |
1502 | * is necessary to make double encryption work with rsaref. Oh, I | |
1503 | * hate software patents. I dont know if this can go? Niels | |
1504 | */ | |
1505 | if (options.server_key_bits > | |
1506 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - | |
1507 | SSH_KEY_BITS_RESERVED && options.server_key_bits < | |
1508 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1509 | SSH_KEY_BITS_RESERVED) { | |
1510 | options.server_key_bits = | |
1511 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1512 | SSH_KEY_BITS_RESERVED; | |
1513 | debug("Forcing server key to %d bits to make it differ from host key.", | |
1514 | options.server_key_bits); | |
1515 | } | |
1516 | } | |
1517 | ||
1518 | if (use_privsep) { | |
1519 | struct stat st; | |
1520 | ||
1521 | if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || | |
1522 | (S_ISDIR(st.st_mode) == 0)) | |
1523 | fatal("Missing privilege separation directory: %s", | |
1524 | _PATH_PRIVSEP_CHROOT_DIR); | |
1525 | ||
1526 | #ifdef HAVE_CYGWIN | |
1527 | if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && | |
1528 | (st.st_uid != getuid () || | |
1529 | (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) | |
1530 | #else | |
1531 | if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) | |
1532 | #endif | |
1533 | fatal("%s must be owned by root and not group or " | |
1534 | "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); | |
1535 | } | |
1536 | ||
1537 | /* Configuration looks good, so exit if in test mode. */ | |
1538 | if (test_flag) | |
1539 | exit(0); | |
1540 | ||
1541 | /* | |
1542 | * Clear out any supplemental groups we may have inherited. This | |
1543 | * prevents inadvertent creation of files with bad modes (in the | |
1544 | * portable version at least, it's certainly possible for PAM | |
1545 | * to create a file, and we can't control the code in every | |
1546 | * module which might be used). | |
1547 | */ | |
1548 | if (setgroups(0, NULL) < 0) | |
1549 | debug("setgroups() failed: %.200s", strerror(errno)); | |
1550 | ||
1551 | if (rexec_flag) { | |
1552 | rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *)); | |
1553 | for (i = 0; i < rexec_argc; i++) { | |
1554 | debug("rexec_argv[%d]='%s'", i, saved_argv[i]); | |
1555 | rexec_argv[i] = saved_argv[i]; | |
1556 | } | |
1557 | rexec_argv[rexec_argc] = "-R"; | |
1558 | rexec_argv[rexec_argc + 1] = NULL; | |
1559 | } | |
1560 | ||
1561 | /* Initialize the log (it is reinitialized below in case we forked). */ | |
1562 | if (debug_flag && (!inetd_flag || rexeced_flag)) | |
1563 | log_stderr = 1; | |
1564 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1565 | ||
1566 | /* | |
1567 | * If not in debugging mode, and not started from inetd, disconnect | |
1568 | * from the controlling terminal, and fork. The original process | |
1569 | * exits. | |
1570 | */ | |
1571 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { | |
1572 | #ifdef TIOCNOTTY | |
1573 | int fd; | |
1574 | #endif /* TIOCNOTTY */ | |
1575 | if (daemon(0, 0) < 0) | |
1576 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1577 | ||
1578 | /* Disconnect from the controlling tty. */ | |
1579 | #ifdef TIOCNOTTY | |
1580 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); | |
1581 | if (fd >= 0) { | |
1582 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
1583 | close(fd); | |
1584 | } | |
1585 | #endif /* TIOCNOTTY */ | |
1586 | } | |
1587 | /* Reinitialize the log (because of the fork above). */ | |
1588 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1589 | ||
1590 | /* Initialize the random number generator. */ | |
1591 | arc4random_stir(); | |
1592 | ||
1593 | /* Chdir to the root directory so that the current disk can be | |
1594 | unmounted if desired. */ | |
1595 | chdir("/"); | |
1596 | ||
1597 | /* ignore SIGPIPE */ | |
1598 | signal(SIGPIPE, SIG_IGN); | |
1599 | ||
1600 | /* Get a connection, either from inetd or a listening TCP socket */ | |
1601 | if (inetd_flag) { | |
1602 | server_accept_inetd(&sock_in, &sock_out); | |
1603 | ||
1604 | if ((options.protocol & SSH_PROTO_1) && | |
1605 | sensitive_data.server_key == NULL) | |
1606 | generate_ephemeral_server_key(); | |
1607 | } else { | |
1608 | server_listen(); | |
1609 | ||
1610 | if (options.protocol & SSH_PROTO_1) | |
1611 | generate_ephemeral_server_key(); | |
1612 | ||
1613 | signal(SIGHUP, sighup_handler); | |
1614 | signal(SIGCHLD, main_sigchld_handler); | |
1615 | signal(SIGTERM, sigterm_handler); | |
1616 | signal(SIGQUIT, sigterm_handler); | |
1617 | ||
1618 | /* | |
1619 | * Write out the pid file after the sigterm handler | |
1620 | * is setup and the listen sockets are bound | |
1621 | */ | |
1622 | if (!debug_flag) { | |
1623 | FILE *f = fopen(options.pid_file, "w"); | |
1624 | ||
1625 | if (f == NULL) { | |
1626 | error("Couldn't create pid file \"%s\": %s", | |
1627 | options.pid_file, strerror(errno)); | |
1628 | } else { | |
1629 | fprintf(f, "%ld\n", (long) getpid()); | |
1630 | fclose(f); | |
1631 | } | |
1632 | } | |
1633 | ||
1634 | /* Accept a connection and return in a forked child */ | |
1635 | server_accept_loop(&sock_in, &sock_out, | |
1636 | &newsock, config_s); | |
1637 | } | |
1638 | ||
1639 | /* This is the child processing a new connection. */ | |
1640 | setproctitle("%s", "[accepted]"); | |
1641 | ||
1642 | /* | |
1643 | * Create a new session and process group since the 4.4BSD | |
1644 | * setlogin() affects the entire process group. We don't | |
1645 | * want the child to be able to affect the parent. | |
1646 | */ | |
1647 | #if !defined(SSHD_ACQUIRES_CTTY) | |
1648 | /* | |
1649 | * If setsid is called, on some platforms sshd will later acquire a | |
1650 | * controlling terminal which will result in "could not set | |
1651 | * controlling tty" errors. | |
1652 | */ | |
1653 | if (!debug_flag && !inetd_flag && setsid() < 0) | |
1654 | error("setsid: %.100s", strerror(errno)); | |
1655 | #endif | |
1656 | ||
1657 | if (rexec_flag) { | |
1658 | int fd; | |
1659 | ||
1660 | debug("rexec start in %d out %d newsock %d pipe %d sock %d", | |
1661 | sock_in, sock_out, newsock, startup_pipe, config_s[0]); | |
1662 | dup2(newsock, STDIN_FILENO); | |
1663 | dup2(STDIN_FILENO, STDOUT_FILENO); | |
1664 | if (startup_pipe == -1) | |
1665 | close(REEXEC_STARTUP_PIPE_FD); | |
1666 | else | |
1667 | dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); | |
1668 | ||
1669 | dup2(config_s[1], REEXEC_CONFIG_PASS_FD); | |
1670 | close(config_s[1]); | |
1671 | if (startup_pipe != -1) | |
1672 | close(startup_pipe); | |
1673 | ||
1674 | execv(rexec_argv[0], rexec_argv); | |
1675 | ||
1676 | /* Reexec has failed, fall back and continue */ | |
1677 | error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); | |
1678 | recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); | |
1679 | log_init(__progname, options.log_level, | |
1680 | options.log_facility, log_stderr); | |
1681 | ||
1682 | /* Clean up fds */ | |
1683 | startup_pipe = REEXEC_STARTUP_PIPE_FD; | |
1684 | close(config_s[1]); | |
1685 | close(REEXEC_CONFIG_PASS_FD); | |
1686 | newsock = sock_out = sock_in = dup(STDIN_FILENO); | |
1687 | if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { | |
1688 | dup2(fd, STDIN_FILENO); | |
1689 | dup2(fd, STDOUT_FILENO); | |
1690 | if (fd > STDERR_FILENO) | |
1691 | close(fd); | |
1692 | } | |
1693 | debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", | |
1694 | sock_in, sock_out, newsock, startup_pipe, config_s[0]); | |
1695 | } | |
1696 | ||
1697 | /* | |
1698 | * Disable the key regeneration alarm. We will not regenerate the | |
1699 | * key since we are no longer in a position to give it to anyone. We | |
1700 | * will not restart on SIGHUP since it no longer makes sense. | |
1701 | */ | |
1702 | alarm(0); | |
1703 | signal(SIGALRM, SIG_DFL); | |
1704 | signal(SIGHUP, SIG_DFL); | |
1705 | signal(SIGTERM, SIG_DFL); | |
1706 | signal(SIGQUIT, SIG_DFL); | |
1707 | signal(SIGCHLD, SIG_DFL); | |
1708 | signal(SIGINT, SIG_DFL); | |
1709 | ||
1710 | /* | |
1711 | * Register our connection. This turns encryption off because we do | |
1712 | * not have a key. | |
1713 | */ | |
1714 | packet_set_connection(sock_in, sock_out); | |
1715 | packet_set_server(); | |
1716 | ||
1717 | /* Set SO_KEEPALIVE if requested. */ | |
1718 | if (options.tcp_keep_alive && packet_connection_is_on_socket() && | |
1719 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) | |
1720 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1721 | ||
1722 | if ((remote_port = get_remote_port()) < 0) { | |
1723 | debug("get_remote_port failed"); | |
1724 | cleanup_exit(255); | |
1725 | } | |
1726 | ||
1727 | /* | |
1728 | * We use get_canonical_hostname with usedns = 0 instead of | |
1729 | * get_remote_ipaddr here so IP options will be checked. | |
1730 | */ | |
1731 | (void) get_canonical_hostname(0); | |
1732 | /* | |
1733 | * The rest of the code depends on the fact that | |
1734 | * get_remote_ipaddr() caches the remote ip, even if | |
1735 | * the socket goes away. | |
1736 | */ | |
1737 | remote_ip = get_remote_ipaddr(); | |
1738 | ||
1739 | #ifdef SSH_AUDIT_EVENTS | |
1740 | audit_connection_from(remote_ip, remote_port); | |
1741 | #endif | |
1742 | #ifdef LIBWRAP | |
1743 | /* Check whether logins are denied from this host. */ | |
1744 | if (packet_connection_is_on_socket()) { | |
1745 | struct request_info req; | |
1746 | ||
1747 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); | |
1748 | fromhost(&req); | |
1749 | ||
1750 | if (!hosts_access(&req)) { | |
1751 | debug("Connection refused by tcp wrapper"); | |
1752 | refuse(&req); | |
1753 | /* NOTREACHED */ | |
1754 | fatal("libwrap refuse returns"); | |
1755 | } | |
1756 | } | |
1757 | #endif /* LIBWRAP */ | |
1758 | ||
1759 | /* Log the connection. */ | |
1760 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
1761 | ||
1762 | /* | |
1763 | * We don't want to listen forever unless the other side | |
1764 | * successfully authenticates itself. So we set up an alarm which is | |
1765 | * cleared after successful authentication. A limit of zero | |
1766 | * indicates no limit. Note that we don't set the alarm in debugging | |
1767 | * mode; it is just annoying to have the server exit just when you | |
1768 | * are about to discover the bug. | |
1769 | */ | |
1770 | signal(SIGALRM, grace_alarm_handler); | |
1771 | if (!debug_flag) | |
1772 | alarm(options.login_grace_time); | |
1773 | ||
1774 | sshd_exchange_identification(sock_in, sock_out); | |
1775 | ||
1776 | packet_set_nonblocking(); | |
1777 | ||
1778 | /* allocate authentication context */ | |
1779 | authctxt = xcalloc(1, sizeof(*authctxt)); | |
1780 | ||
1781 | authctxt->loginmsg = &loginmsg; | |
1782 | ||
1783 | /* XXX global for cleanup, access from other modules */ | |
1784 | the_authctxt = authctxt; | |
1785 | ||
1786 | /* prepare buffer to collect messages to display to user after login */ | |
1787 | buffer_init(&loginmsg); | |
1788 | ||
1789 | if (use_privsep) | |
1790 | if (privsep_preauth(authctxt) == 1) | |
1791 | goto authenticated; | |
1792 | ||
1793 | /* perform the key exchange */ | |
1794 | /* authenticate user and start session */ | |
1795 | if (compat20) { | |
1796 | do_ssh2_kex(); | |
1797 | do_authentication2(authctxt); | |
1798 | } else { | |
1799 | do_ssh1_kex(); | |
1800 | do_authentication(authctxt); | |
1801 | } | |
1802 | /* | |
1803 | * If we use privilege separation, the unprivileged child transfers | |
1804 | * the current keystate and exits | |
1805 | */ | |
1806 | if (use_privsep) { | |
1807 | mm_send_keystate(pmonitor); | |
1808 | exit(0); | |
1809 | } | |
1810 | ||
1811 | authenticated: | |
1812 | /* | |
1813 | * Cancel the alarm we set to limit the time taken for | |
1814 | * authentication. | |
1815 | */ | |
1816 | alarm(0); | |
1817 | signal(SIGALRM, SIG_DFL); | |
1818 | authctxt->authenticated = 1; | |
1819 | if (startup_pipe != -1) { | |
1820 | close(startup_pipe); | |
1821 | startup_pipe = -1; | |
1822 | } | |
1823 | ||
1824 | #ifdef SSH_AUDIT_EVENTS | |
1825 | audit_event(SSH_AUTH_SUCCESS); | |
1826 | #endif | |
1827 | ||
1828 | /* | |
1829 | * In privilege separation, we fork another child and prepare | |
1830 | * file descriptor passing. | |
1831 | */ | |
1832 | if (use_privsep) { | |
1833 | privsep_postauth(authctxt); | |
1834 | /* the monitor process [priv] will not return */ | |
1835 | if (!compat20) | |
1836 | destroy_sensitive_data(); | |
1837 | } | |
1838 | ||
1839 | /* Start session. */ | |
1840 | do_authenticated(authctxt); | |
1841 | ||
1842 | /* The connection has been terminated. */ | |
1843 | verbose("Closing connection to %.100s", remote_ip); | |
1844 | ||
1845 | #ifdef USE_PAM | |
1846 | if (options.use_pam) | |
1847 | finish_pam(); | |
1848 | #endif /* USE_PAM */ | |
1849 | ||
1850 | #ifdef SSH_AUDIT_EVENTS | |
1851 | PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); | |
1852 | #endif | |
1853 | ||
1854 | packet_close(); | |
1855 | ||
1856 | if (use_privsep) | |
1857 | mm_terminate(); | |
1858 | ||
1859 | exit(0); | |
1860 | } | |
1861 | ||
1862 | /* | |
1863 | * Decrypt session_key_int using our private server key and private host key | |
1864 | * (key with larger modulus first). | |
1865 | */ | |
1866 | int | |
1867 | ssh1_session_key(BIGNUM *session_key_int) | |
1868 | { | |
1869 | int rsafail = 0; | |
1870 | ||
1871 | if (BN_cmp(sensitive_data.server_key->rsa->n, | |
1872 | sensitive_data.ssh1_host_key->rsa->n) > 0) { | |
1873 | /* Server key has bigger modulus. */ | |
1874 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < | |
1875 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1876 | SSH_KEY_BITS_RESERVED) { | |
1877 | fatal("do_connection: %s: " | |
1878 | "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1879 | get_remote_ipaddr(), | |
1880 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1881 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1882 | SSH_KEY_BITS_RESERVED); | |
1883 | } | |
1884 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1885 | sensitive_data.server_key->rsa) <= 0) | |
1886 | rsafail++; | |
1887 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1888 | sensitive_data.ssh1_host_key->rsa) <= 0) | |
1889 | rsafail++; | |
1890 | } else { | |
1891 | /* Host key has bigger modulus (or they are equal). */ | |
1892 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < | |
1893 | BN_num_bits(sensitive_data.server_key->rsa->n) + | |
1894 | SSH_KEY_BITS_RESERVED) { | |
1895 | fatal("do_connection: %s: " | |
1896 | "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1897 | get_remote_ipaddr(), | |
1898 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1899 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1900 | SSH_KEY_BITS_RESERVED); | |
1901 | } | |
1902 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1903 | sensitive_data.ssh1_host_key->rsa) < 0) | |
1904 | rsafail++; | |
1905 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1906 | sensitive_data.server_key->rsa) < 0) | |
1907 | rsafail++; | |
1908 | } | |
1909 | return (rsafail); | |
1910 | } | |
1911 | /* | |
1912 | * SSH1 key exchange | |
1913 | */ | |
1914 | static void | |
1915 | do_ssh1_kex(void) | |
1916 | { | |
1917 | int i, len; | |
1918 | int rsafail = 0; | |
1919 | BIGNUM *session_key_int; | |
1920 | u_char session_key[SSH_SESSION_KEY_LENGTH]; | |
1921 | u_char cookie[8]; | |
1922 | u_int cipher_type, auth_mask, protocol_flags; | |
1923 | u_int32_t rnd = 0; | |
1924 | ||
1925 | /* | |
1926 | * Generate check bytes that the client must send back in the user | |
1927 | * packet in order for it to be accepted; this is used to defy ip | |
1928 | * spoofing attacks. Note that this only works against somebody | |
1929 | * doing IP spoofing from a remote machine; any machine on the local | |
1930 | * network can still see outgoing packets and catch the random | |
1931 | * cookie. This only affects rhosts authentication, and this is one | |
1932 | * of the reasons why it is inherently insecure. | |
1933 | */ | |
1934 | for (i = 0; i < 8; i++) { | |
1935 | if (i % 4 == 0) | |
1936 | rnd = arc4random(); | |
1937 | cookie[i] = rnd & 0xff; | |
1938 | rnd >>= 8; | |
1939 | } | |
1940 | ||
1941 | /* | |
1942 | * Send our public key. We include in the packet 64 bits of random | |
1943 | * data that must be matched in the reply in order to prevent IP | |
1944 | * spoofing. | |
1945 | */ | |
1946 | packet_start(SSH_SMSG_PUBLIC_KEY); | |
1947 | for (i = 0; i < 8; i++) | |
1948 | packet_put_char(cookie[i]); | |
1949 | ||
1950 | /* Store our public server RSA key. */ | |
1951 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); | |
1952 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1953 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
1954 | ||
1955 | /* Store our public host RSA key. */ | |
1956 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
1957 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1958 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
1959 | ||
1960 | /* Put protocol flags. */ | |
1961 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1962 | ||
1963 | /* Declare which ciphers we support. */ | |
1964 | packet_put_int(cipher_mask_ssh1(0)); | |
1965 | ||
1966 | /* Declare supported authentication types. */ | |
1967 | auth_mask = 0; | |
1968 | if (options.rhosts_rsa_authentication) | |
1969 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1970 | if (options.rsa_authentication) | |
1971 | auth_mask |= 1 << SSH_AUTH_RSA; | |
1972 | if (options.challenge_response_authentication == 1) | |
1973 | auth_mask |= 1 << SSH_AUTH_TIS; | |
1974 | if (options.password_authentication) | |
1975 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1976 | packet_put_int(auth_mask); | |
1977 | ||
1978 | /* Send the packet and wait for it to be sent. */ | |
1979 | packet_send(); | |
1980 | packet_write_wait(); | |
1981 | ||
1982 | debug("Sent %d bit server key and %d bit host key.", | |
1983 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1984 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
1985 | ||
1986 | /* Read clients reply (cipher type and session key). */ | |
1987 | packet_read_expect(SSH_CMSG_SESSION_KEY); | |
1988 | ||
1989 | /* Get cipher type and check whether we accept this. */ | |
1990 | cipher_type = packet_get_char(); | |
1991 | ||
1992 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) | |
1993 | packet_disconnect("Warning: client selects unsupported cipher."); | |
1994 | ||
1995 | /* Get check bytes from the packet. These must match those we | |
1996 | sent earlier with the public key packet. */ | |
1997 | for (i = 0; i < 8; i++) | |
1998 | if (cookie[i] != packet_get_char()) | |
1999 | packet_disconnect("IP Spoofing check bytes do not match."); | |
2000 | ||
2001 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
2002 | ||
2003 | /* Get the encrypted integer. */ | |
2004 | if ((session_key_int = BN_new()) == NULL) | |
2005 | fatal("do_ssh1_kex: BN_new failed"); | |
2006 | packet_get_bignum(session_key_int); | |
2007 | ||
2008 | protocol_flags = packet_get_int(); | |
2009 | packet_set_protocol_flags(protocol_flags); | |
2010 | packet_check_eom(); | |
2011 | ||
2012 | /* Decrypt session_key_int using host/server keys */ | |
2013 | rsafail = PRIVSEP(ssh1_session_key(session_key_int)); | |
2014 | ||
2015 | /* | |
2016 | * Extract session key from the decrypted integer. The key is in the | |
2017 | * least significant 256 bits of the integer; the first byte of the | |
2018 | * key is in the highest bits. | |
2019 | */ | |
2020 | if (!rsafail) { | |
2021 | (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
2022 | len = BN_num_bytes(session_key_int); | |
2023 | if (len < 0 || (u_int)len > sizeof(session_key)) { | |
2024 | error("do_ssh1_kex: bad session key len from %s: " | |
2025 | "session_key_int %d > sizeof(session_key) %lu", | |
2026 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); | |
2027 | rsafail++; | |
2028 | } else { | |
2029 | memset(session_key, 0, sizeof(session_key)); | |
2030 | BN_bn2bin(session_key_int, | |
2031 | session_key + sizeof(session_key) - len); | |
2032 | ||
2033 | derive_ssh1_session_id( | |
2034 | sensitive_data.ssh1_host_key->rsa->n, | |
2035 | sensitive_data.server_key->rsa->n, | |
2036 | cookie, session_id); | |
2037 | /* | |
2038 | * Xor the first 16 bytes of the session key with the | |
2039 | * session id. | |
2040 | */ | |
2041 | for (i = 0; i < 16; i++) | |
2042 | session_key[i] ^= session_id[i]; | |
2043 | } | |
2044 | } | |
2045 | if (rsafail) { | |
2046 | int bytes = BN_num_bytes(session_key_int); | |
2047 | u_char *buf = xmalloc(bytes); | |
2048 | MD5_CTX md; | |
2049 | ||
2050 | logit("do_connection: generating a fake encryption key"); | |
2051 | BN_bn2bin(session_key_int, buf); | |
2052 | MD5_Init(&md); | |
2053 | MD5_Update(&md, buf, bytes); | |
2054 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
2055 | MD5_Final(session_key, &md); | |
2056 | MD5_Init(&md); | |
2057 | MD5_Update(&md, session_key, 16); | |
2058 | MD5_Update(&md, buf, bytes); | |
2059 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
2060 | MD5_Final(session_key + 16, &md); | |
2061 | memset(buf, 0, bytes); | |
2062 | xfree(buf); | |
2063 | for (i = 0; i < 16; i++) | |
2064 | session_id[i] = session_key[i] ^ session_key[i + 16]; | |
2065 | } | |
2066 | /* Destroy the private and public keys. No longer. */ | |
2067 | destroy_sensitive_data(); | |
2068 | ||
2069 | if (use_privsep) | |
2070 | mm_ssh1_session_id(session_id); | |
2071 | ||
2072 | /* Destroy the decrypted integer. It is no longer needed. */ | |
2073 | BN_clear_free(session_key_int); | |
2074 | ||
2075 | /* Set the session key. From this on all communications will be encrypted. */ | |
2076 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
2077 | ||
2078 | /* Destroy our copy of the session key. It is no longer needed. */ | |
2079 | memset(session_key, 0, sizeof(session_key)); | |
2080 | ||
2081 | debug("Received session key; encryption turned on."); | |
2082 | ||
2083 | /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ | |
2084 | packet_start(SSH_SMSG_SUCCESS); | |
2085 | packet_send(); | |
2086 | packet_write_wait(); | |
2087 | } | |
2088 | ||
2089 | /* | |
2090 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
2091 | */ | |
2092 | static void | |
2093 | do_ssh2_kex(void) | |
2094 | { | |
2095 | Kex *kex; | |
2096 | ||
2097 | if (options.ciphers != NULL) { | |
2098 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
2099 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; | |
2100 | } | |
2101 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
2102 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); | |
2103 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
2104 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); | |
2105 | ||
2106 | if (options.macs != NULL) { | |
2107 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
2108 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
2109 | } | |
2110 | if (options.compression == COMP_NONE) { | |
2111 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
2112 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
2113 | } else if (options.compression == COMP_DELAYED) { | |
2114 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
2115 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; | |
2116 | } | |
2117 | ||
2118 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); | |
2119 | ||
2120 | /* start key exchange */ | |
2121 | kex = kex_setup(myproposal); | |
2122 | kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; | |
2123 | kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; | |
2124 | kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; | |
2125 | kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; | |
2126 | kex->server = 1; | |
2127 | kex->client_version_string=client_version_string; | |
2128 | kex->server_version_string=server_version_string; | |
2129 | kex->load_host_key=&get_hostkey_by_type; | |
2130 | kex->host_key_index=&get_hostkey_index; | |
2131 | ||
2132 | xxx_kex = kex; | |
2133 | ||
2134 | dispatch_run(DISPATCH_BLOCK, &kex->done, kex); | |
2135 | ||
2136 | session_id2 = kex->session_id; | |
2137 | session_id2_len = kex->session_id_len; | |
2138 | ||
2139 | #ifdef DEBUG_KEXDH | |
2140 | /* send 1st encrypted/maced/compressed message */ | |
2141 | packet_start(SSH2_MSG_IGNORE); | |
2142 | packet_put_cstring("markus"); | |
2143 | packet_send(); | |
2144 | packet_write_wait(); | |
2145 | #endif | |
2146 | debug("KEX done"); | |
2147 | } | |
2148 | ||
2149 | /* server specific fatal cleanup */ | |
2150 | void | |
2151 | cleanup_exit(int i) | |
2152 | { | |
2153 | if (the_authctxt) | |
2154 | do_cleanup(the_authctxt); | |
2155 | #ifdef SSH_AUDIT_EVENTS | |
2156 | /* done after do_cleanup so it can cancel the PAM auth 'thread' */ | |
2157 | if (!use_privsep || mm_is_monitor()) | |
2158 | audit_event(SSH_CONNECTION_ABANDON); | |
2159 | #endif | |
2160 | _exit(i); | |
2161 | } |