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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 1.318 2005/12/24 02:27:41 djm 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 "log.h" | |
64 | #include "servconf.h" | |
65 | #include "uidswap.h" | |
66 | #include "compat.h" | |
67 | #include "buffer.h" | |
68 | #include "bufaux.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 "msg.h" | |
81 | #include "dispatch.h" | |
82 | #include "channels.h" | |
83 | #include "session.h" | |
84 | #include "monitor_mm.h" | |
85 | #include "monitor.h" | |
86 | #include "monitor_wrap.h" | |
87 | #include "monitor_fdpass.h" | |
88 | ||
89 | #ifdef LIBWRAP | |
90 | #include <tcpd.h> | |
91 | #include <syslog.h> | |
92 | int allow_severity = LOG_INFO; | |
93 | int deny_severity = LOG_WARNING; | |
94 | #endif /* LIBWRAP */ | |
95 | ||
96 | #ifndef O_NOCTTY | |
97 | #define O_NOCTTY 0 | |
98 | #endif | |
99 | ||
100 | /* Re-exec fds */ | |
101 | #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1) | |
102 | #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2) | |
103 | #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3) | |
104 | #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4) | |
105 | ||
106 | extern char *__progname; | |
107 | ||
108 | /* Server configuration options. */ | |
109 | ServerOptions options; | |
110 | ||
111 | /* Name of the server configuration file. */ | |
112 | char *config_file_name = _PATH_SERVER_CONFIG_FILE; | |
113 | ||
114 | /* | |
115 | * Debug mode flag. This can be set on the command line. If debug | |
116 | * mode is enabled, extra debugging output will be sent to the system | |
117 | * log, the daemon will not go to background, and will exit after processing | |
118 | * the first connection. | |
119 | */ | |
120 | int debug_flag = 0; | |
121 | ||
122 | /* Flag indicating that the daemon should only test the configuration and keys. */ | |
123 | int test_flag = 0; | |
124 | ||
125 | /* Flag indicating that the daemon is being started from inetd. */ | |
126 | int inetd_flag = 0; | |
127 | ||
128 | /* Flag indicating that sshd should not detach and become a daemon. */ | |
129 | int no_daemon_flag = 0; | |
130 | ||
131 | /* debug goes to stderr unless inetd_flag is set */ | |
132 | int log_stderr = 0; | |
133 | ||
134 | /* Saved arguments to main(). */ | |
135 | char **saved_argv; | |
136 | int saved_argc; | |
137 | ||
138 | /* re-exec */ | |
139 | int rexeced_flag = 0; | |
140 | int rexec_flag = 1; | |
141 | int rexec_argc = 0; | |
142 | char **rexec_argv; | |
143 | ||
144 | /* | |
145 | * The sockets that the server is listening; this is used in the SIGHUP | |
146 | * signal handler. | |
147 | */ | |
148 | #define MAX_LISTEN_SOCKS 16 | |
149 | int listen_socks[MAX_LISTEN_SOCKS]; | |
150 | int num_listen_socks = 0; | |
151 | ||
152 | /* | |
153 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
154 | * sshd will skip the version-number exchange | |
155 | */ | |
156 | char *client_version_string = NULL; | |
157 | char *server_version_string = NULL; | |
158 | ||
159 | /* for rekeying XXX fixme */ | |
160 | Kex *xxx_kex; | |
161 | ||
162 | /* | |
163 | * Any really sensitive data in the application is contained in this | |
164 | * structure. The idea is that this structure could be locked into memory so | |
165 | * that the pages do not get written into swap. However, there are some | |
166 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
167 | * have access to the internals of them, and locking just the structure is | |
168 | * not very useful. Currently, memory locking is not implemented. | |
169 | */ | |
170 | struct { | |
171 | Key *server_key; /* ephemeral server key */ | |
172 | Key *ssh1_host_key; /* ssh1 host key */ | |
173 | Key **host_keys; /* all private host keys */ | |
174 | int have_ssh1_key; | |
175 | int have_ssh2_key; | |
176 | u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; | |
177 | } sensitive_data; | |
178 | ||
179 | /* | |
180 | * Flag indicating whether the RSA server key needs to be regenerated. | |
181 | * Is set in the SIGALRM handler and cleared when the key is regenerated. | |
182 | */ | |
183 | static volatile sig_atomic_t key_do_regen = 0; | |
184 | ||
185 | /* This is set to true when a signal is received. */ | |
186 | static volatile sig_atomic_t received_sighup = 0; | |
187 | static volatile sig_atomic_t received_sigterm = 0; | |
188 | ||
189 | /* session identifier, used by RSA-auth */ | |
190 | u_char session_id[16]; | |
191 | ||
192 | /* same for ssh2 */ | |
193 | u_char *session_id2 = NULL; | |
194 | u_int session_id2_len = 0; | |
195 | ||
196 | /* record remote hostname or ip */ | |
197 | u_int utmp_len = MAXHOSTNAMELEN; | |
198 | ||
199 | /* options.max_startup sized array of fd ints */ | |
200 | int *startup_pipes = NULL; | |
201 | int startup_pipe; /* in child */ | |
202 | ||
203 | /* variables used for privilege separation */ | |
204 | int use_privsep; | |
205 | struct monitor *pmonitor = NULL; | |
206 | ||
207 | /* global authentication context */ | |
208 | Authctxt *the_authctxt = NULL; | |
209 | ||
210 | /* message to be displayed after login */ | |
211 | Buffer loginmsg; | |
212 | ||
213 | /* Prototypes for various functions defined later in this file. */ | |
214 | void destroy_sensitive_data(void); | |
215 | void demote_sensitive_data(void); | |
216 | ||
217 | static void do_ssh1_kex(void); | |
218 | static void do_ssh2_kex(void); | |
219 | ||
220 | /* | |
221 | * Close all listening sockets | |
222 | */ | |
223 | static void | |
224 | close_listen_socks(void) | |
225 | { | |
226 | int i; | |
227 | ||
228 | for (i = 0; i < num_listen_socks; i++) | |
229 | close(listen_socks[i]); | |
230 | num_listen_socks = -1; | |
231 | } | |
232 | ||
233 | static void | |
234 | close_startup_pipes(void) | |
235 | { | |
236 | int i; | |
237 | ||
238 | if (startup_pipes) | |
239 | for (i = 0; i < options.max_startups; i++) | |
240 | if (startup_pipes[i] != -1) | |
241 | close(startup_pipes[i]); | |
242 | } | |
243 | ||
244 | /* | |
245 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
246 | * the effect is to reread the configuration file (and to regenerate | |
247 | * the server key). | |
248 | */ | |
249 | static void | |
250 | sighup_handler(int sig) | |
251 | { | |
252 | int save_errno = errno; | |
253 | ||
254 | received_sighup = 1; | |
255 | signal(SIGHUP, sighup_handler); | |
256 | errno = save_errno; | |
257 | } | |
258 | ||
259 | /* | |
260 | * Called from the main program after receiving SIGHUP. | |
261 | * Restarts the server. | |
262 | */ | |
263 | static void | |
264 | sighup_restart(void) | |
265 | { | |
266 | logit("Received SIGHUP; restarting."); | |
267 | close_listen_socks(); | |
268 | close_startup_pipes(); | |
269 | execv(saved_argv[0], saved_argv); | |
270 | logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], | |
271 | strerror(errno)); | |
272 | exit(1); | |
273 | } | |
274 | ||
275 | /* | |
276 | * Generic signal handler for terminating signals in the master daemon. | |
277 | */ | |
278 | static void | |
279 | sigterm_handler(int sig) | |
280 | { | |
281 | received_sigterm = sig; | |
282 | } | |
283 | ||
284 | /* | |
285 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
286 | * reap any zombies left by exited children. | |
287 | */ | |
288 | static void | |
289 | main_sigchld_handler(int sig) | |
290 | { | |
291 | int save_errno = errno; | |
292 | pid_t pid; | |
293 | int status; | |
294 | ||
295 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || | |
296 | (pid < 0 && errno == EINTR)) | |
297 | ; | |
298 | ||
299 | signal(SIGCHLD, main_sigchld_handler); | |
300 | errno = save_errno; | |
301 | } | |
302 | ||
303 | /* | |
304 | * Signal handler for the alarm after the login grace period has expired. | |
305 | */ | |
306 | static void | |
307 | grace_alarm_handler(int sig) | |
308 | { | |
309 | /* XXX no idea how fix this signal handler */ | |
310 | ||
311 | if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) | |
312 | kill(pmonitor->m_pid, SIGALRM); | |
313 | ||
314 | /* Log error and exit. */ | |
315 | fatal("Timeout before authentication for %s", get_remote_ipaddr()); | |
316 | } | |
317 | ||
318 | /* | |
319 | * Signal handler for the key regeneration alarm. Note that this | |
320 | * alarm only occurs in the daemon waiting for connections, and it does not | |
321 | * do anything with the private key or random state before forking. | |
322 | * Thus there should be no concurrency control/asynchronous execution | |
323 | * problems. | |
324 | */ | |
325 | static void | |
326 | generate_ephemeral_server_key(void) | |
327 | { | |
328 | u_int32_t rnd = 0; | |
329 | int i; | |
330 | ||
331 | verbose("Generating %s%d bit RSA key.", | |
332 | sensitive_data.server_key ? "new " : "", options.server_key_bits); | |
333 | if (sensitive_data.server_key != NULL) | |
334 | key_free(sensitive_data.server_key); | |
335 | sensitive_data.server_key = key_generate(KEY_RSA1, | |
336 | options.server_key_bits); | |
337 | verbose("RSA key generation complete."); | |
338 | ||
339 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
340 | if (i % 4 == 0) | |
341 | rnd = arc4random(); | |
342 | sensitive_data.ssh1_cookie[i] = rnd & 0xff; | |
343 | rnd >>= 8; | |
344 | } | |
345 | arc4random_stir(); | |
346 | } | |
347 | ||
348 | static void | |
349 | key_regeneration_alarm(int sig) | |
350 | { | |
351 | int save_errno = errno; | |
352 | ||
353 | signal(SIGALRM, SIG_DFL); | |
354 | errno = save_errno; | |
355 | key_do_regen = 1; | |
356 | } | |
357 | ||
358 | static void | |
359 | sshd_exchange_identification(int sock_in, int sock_out) | |
360 | { | |
361 | u_int i; | |
362 | int mismatch; | |
363 | int remote_major, remote_minor; | |
364 | int major, minor; | |
365 | char *s; | |
366 | char buf[256]; /* Must not be larger than remote_version. */ | |
367 | char remote_version[256]; /* Must be at least as big as buf. */ | |
368 | ||
369 | if ((options.protocol & SSH_PROTO_1) && | |
370 | (options.protocol & SSH_PROTO_2)) { | |
371 | major = PROTOCOL_MAJOR_1; | |
372 | minor = 99; | |
373 | } else if (options.protocol & SSH_PROTO_2) { | |
374 | major = PROTOCOL_MAJOR_2; | |
375 | minor = PROTOCOL_MINOR_2; | |
376 | } else { | |
377 | major = PROTOCOL_MAJOR_1; | |
378 | minor = PROTOCOL_MINOR_1; | |
379 | } | |
380 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
381 | server_version_string = xstrdup(buf); | |
382 | ||
383 | /* Send our protocol version identification. */ | |
384 | if (atomicio(vwrite, sock_out, server_version_string, | |
385 | strlen(server_version_string)) | |
386 | != strlen(server_version_string)) { | |
387 | logit("Could not write ident string to %s", get_remote_ipaddr()); | |
388 | cleanup_exit(255); | |
389 | } | |
390 | ||
391 | /* Read other sides version identification. */ | |
392 | memset(buf, 0, sizeof(buf)); | |
393 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
394 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { | |
395 | logit("Did not receive identification string from %s", | |
396 | get_remote_ipaddr()); | |
397 | cleanup_exit(255); | |
398 | } | |
399 | if (buf[i] == '\r') { | |
400 | buf[i] = 0; | |
401 | /* Kludge for F-Secure Macintosh < 1.0.2 */ | |
402 | if (i == 12 && | |
403 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
404 | break; | |
405 | continue; | |
406 | } | |
407 | if (buf[i] == '\n') { | |
408 | buf[i] = 0; | |
409 | break; | |
410 | } | |
411 | } | |
412 | buf[sizeof(buf) - 1] = 0; | |
413 | client_version_string = xstrdup(buf); | |
414 | ||
415 | /* | |
416 | * Check that the versions match. In future this might accept | |
417 | * several versions and set appropriate flags to handle them. | |
418 | */ | |
419 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
420 | &remote_major, &remote_minor, remote_version) != 3) { | |
421 | s = "Protocol mismatch.\n"; | |
422 | (void) atomicio(vwrite, sock_out, s, strlen(s)); | |
423 | close(sock_in); | |
424 | close(sock_out); | |
425 | logit("Bad protocol version identification '%.100s' from %s", | |
426 | client_version_string, get_remote_ipaddr()); | |
427 | cleanup_exit(255); | |
428 | } | |
429 | debug("Client protocol version %d.%d; client software version %.100s", | |
430 | remote_major, remote_minor, remote_version); | |
431 | ||
432 | compat_datafellows(remote_version); | |
433 | ||
434 | if (datafellows & SSH_BUG_PROBE) { | |
435 | logit("probed from %s with %s. Don't panic.", | |
436 | get_remote_ipaddr(), client_version_string); | |
437 | cleanup_exit(255); | |
438 | } | |
439 | ||
440 | if (datafellows & SSH_BUG_SCANNER) { | |
441 | logit("scanned from %s with %s. Don't panic.", | |
442 | get_remote_ipaddr(), client_version_string); | |
443 | cleanup_exit(255); | |
444 | } | |
445 | ||
446 | mismatch = 0; | |
447 | switch (remote_major) { | |
448 | case 1: | |
449 | if (remote_minor == 99) { | |
450 | if (options.protocol & SSH_PROTO_2) | |
451 | enable_compat20(); | |
452 | else | |
453 | mismatch = 1; | |
454 | break; | |
455 | } | |
456 | if (!(options.protocol & SSH_PROTO_1)) { | |
457 | mismatch = 1; | |
458 | break; | |
459 | } | |
460 | if (remote_minor < 3) { | |
461 | packet_disconnect("Your ssh version is too old and " | |
462 | "is no longer supported. Please install a newer version."); | |
463 | } else if (remote_minor == 3) { | |
464 | /* note that this disables agent-forwarding */ | |
465 | enable_compat13(); | |
466 | } | |
467 | break; | |
468 | case 2: | |
469 | if (options.protocol & SSH_PROTO_2) { | |
470 | enable_compat20(); | |
471 | break; | |
472 | } | |
473 | /* FALLTHROUGH */ | |
474 | default: | |
475 | mismatch = 1; | |
476 | break; | |
477 | } | |
478 | chop(server_version_string); | |
479 | debug("Local version string %.200s", server_version_string); | |
480 | ||
481 | if (mismatch) { | |
482 | s = "Protocol major versions differ.\n"; | |
483 | (void) atomicio(vwrite, sock_out, s, strlen(s)); | |
484 | close(sock_in); | |
485 | close(sock_out); | |
486 | logit("Protocol major versions differ for %s: %.200s vs. %.200s", | |
487 | get_remote_ipaddr(), | |
488 | server_version_string, client_version_string); | |
489 | cleanup_exit(255); | |
490 | } | |
491 | } | |
492 | ||
493 | /* Destroy the host and server keys. They will no longer be needed. */ | |
494 | void | |
495 | destroy_sensitive_data(void) | |
496 | { | |
497 | int i; | |
498 | ||
499 | if (sensitive_data.server_key) { | |
500 | key_free(sensitive_data.server_key); | |
501 | sensitive_data.server_key = NULL; | |
502 | } | |
503 | for (i = 0; i < options.num_host_key_files; i++) { | |
504 | if (sensitive_data.host_keys[i]) { | |
505 | key_free(sensitive_data.host_keys[i]); | |
506 | sensitive_data.host_keys[i] = NULL; | |
507 | } | |
508 | } | |
509 | sensitive_data.ssh1_host_key = NULL; | |
510 | memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); | |
511 | } | |
512 | ||
513 | /* Demote private to public keys for network child */ | |
514 | void | |
515 | demote_sensitive_data(void) | |
516 | { | |
517 | Key *tmp; | |
518 | int i; | |
519 | ||
520 | if (sensitive_data.server_key) { | |
521 | tmp = key_demote(sensitive_data.server_key); | |
522 | key_free(sensitive_data.server_key); | |
523 | sensitive_data.server_key = tmp; | |
524 | } | |
525 | ||
526 | for (i = 0; i < options.num_host_key_files; i++) { | |
527 | if (sensitive_data.host_keys[i]) { | |
528 | tmp = key_demote(sensitive_data.host_keys[i]); | |
529 | key_free(sensitive_data.host_keys[i]); | |
530 | sensitive_data.host_keys[i] = tmp; | |
531 | if (tmp->type == KEY_RSA1) | |
532 | sensitive_data.ssh1_host_key = tmp; | |
533 | } | |
534 | } | |
535 | ||
536 | /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ | |
537 | } | |
538 | ||
539 | static void | |
540 | privsep_preauth_child(void) | |
541 | { | |
542 | u_int32_t rnd[256]; | |
543 | gid_t gidset[1]; | |
544 | struct passwd *pw; | |
545 | int i; | |
546 | ||
547 | /* Enable challenge-response authentication for privilege separation */ | |
548 | privsep_challenge_enable(); | |
549 | ||
550 | for (i = 0; i < 256; i++) | |
551 | rnd[i] = arc4random(); | |
552 | RAND_seed(rnd, sizeof(rnd)); | |
553 | ||
554 | /* Demote the private keys to public keys. */ | |
555 | demote_sensitive_data(); | |
556 | ||
557 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
558 | fatal("Privilege separation user %s does not exist", | |
559 | SSH_PRIVSEP_USER); | |
560 | memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); | |
561 | endpwent(); | |
562 | ||
563 | /* Change our root directory */ | |
564 | if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) | |
565 | fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, | |
566 | strerror(errno)); | |
567 | if (chdir("/") == -1) | |
568 | fatal("chdir(\"/\"): %s", strerror(errno)); | |
569 | ||
570 | /* Drop our privileges */ | |
571 | debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, | |
572 | (u_int)pw->pw_gid); | |
573 | #if 0 | |
574 | /* XXX not ready, too heavy after chroot */ | |
575 | do_setusercontext(pw); | |
576 | #else | |
577 | gidset[0] = pw->pw_gid; | |
578 | if (setgroups(1, gidset) < 0) | |
579 | fatal("setgroups: %.100s", strerror(errno)); | |
580 | permanently_set_uid(pw); | |
581 | #endif | |
582 | } | |
583 | ||
584 | static int | |
585 | privsep_preauth(Authctxt *authctxt) | |
586 | { | |
587 | int status; | |
588 | pid_t pid; | |
589 | ||
590 | /* Set up unprivileged child process to deal with network data */ | |
591 | pmonitor = monitor_init(); | |
592 | /* Store a pointer to the kex for later rekeying */ | |
593 | pmonitor->m_pkex = &xxx_kex; | |
594 | ||
595 | pid = fork(); | |
596 | if (pid == -1) { | |
597 | fatal("fork of unprivileged child failed"); | |
598 | } else if (pid != 0) { | |
599 | debug2("Network child is on pid %ld", (long)pid); | |
600 | ||
601 | close(pmonitor->m_recvfd); | |
602 | pmonitor->m_pid = pid; | |
603 | monitor_child_preauth(authctxt, pmonitor); | |
604 | close(pmonitor->m_sendfd); | |
605 | ||
606 | /* Sync memory */ | |
607 | monitor_sync(pmonitor); | |
608 | ||
609 | /* Wait for the child's exit status */ | |
610 | while (waitpid(pid, &status, 0) < 0) | |
611 | if (errno != EINTR) | |
612 | break; | |
613 | return (1); | |
614 | } else { | |
615 | /* child */ | |
616 | ||
617 | close(pmonitor->m_sendfd); | |
618 | ||
619 | /* Demote the child */ | |
620 | if (getuid() == 0 || geteuid() == 0) | |
621 | privsep_preauth_child(); | |
622 | setproctitle("%s", "[net]"); | |
623 | } | |
624 | return (0); | |
625 | } | |
626 | ||
627 | static void | |
628 | privsep_postauth(Authctxt *authctxt) | |
629 | { | |
630 | #ifdef DISABLE_FD_PASSING | |
631 | if (1) { | |
632 | #else | |
633 | if (authctxt->pw->pw_uid == 0 || options.use_login) { | |
634 | #endif | |
635 | /* File descriptor passing is broken or root login */ | |
636 | use_privsep = 0; | |
637 | goto skip; | |
638 | } | |
639 | ||
640 | /* New socket pair */ | |
641 | monitor_reinit(pmonitor); | |
642 | ||
643 | pmonitor->m_pid = fork(); | |
644 | if (pmonitor->m_pid == -1) | |
645 | fatal("fork of unprivileged child failed"); | |
646 | else if (pmonitor->m_pid != 0) { | |
647 | debug2("User child is on pid %ld", (long)pmonitor->m_pid); | |
648 | close(pmonitor->m_recvfd); | |
649 | buffer_clear(&loginmsg); | |
650 | monitor_child_postauth(pmonitor); | |
651 | ||
652 | /* NEVERREACHED */ | |
653 | exit(0); | |
654 | } | |
655 | ||
656 | close(pmonitor->m_sendfd); | |
657 | ||
658 | /* Demote the private keys to public keys. */ | |
659 | demote_sensitive_data(); | |
660 | ||
661 | /* Drop privileges */ | |
662 | do_setusercontext(authctxt->pw); | |
663 | ||
664 | skip: | |
665 | /* It is safe now to apply the key state */ | |
666 | monitor_apply_keystate(pmonitor); | |
667 | ||
668 | /* | |
669 | * Tell the packet layer that authentication was successful, since | |
670 | * this information is not part of the key state. | |
671 | */ | |
672 | packet_set_authenticated(); | |
673 | } | |
674 | ||
675 | static char * | |
676 | list_hostkey_types(void) | |
677 | { | |
678 | Buffer b; | |
679 | const char *p; | |
680 | char *ret; | |
681 | int i; | |
682 | ||
683 | buffer_init(&b); | |
684 | for (i = 0; i < options.num_host_key_files; i++) { | |
685 | Key *key = sensitive_data.host_keys[i]; | |
686 | if (key == NULL) | |
687 | continue; | |
688 | switch (key->type) { | |
689 | case KEY_RSA: | |
690 | case KEY_DSA: | |
691 | if (buffer_len(&b) > 0) | |
692 | buffer_append(&b, ",", 1); | |
693 | p = key_ssh_name(key); | |
694 | buffer_append(&b, p, strlen(p)); | |
695 | break; | |
696 | } | |
697 | } | |
698 | buffer_append(&b, "\0", 1); | |
699 | ret = xstrdup(buffer_ptr(&b)); | |
700 | buffer_free(&b); | |
701 | debug("list_hostkey_types: %s", ret); | |
702 | return ret; | |
703 | } | |
704 | ||
705 | Key * | |
706 | get_hostkey_by_type(int type) | |
707 | { | |
708 | int i; | |
709 | ||
710 | for (i = 0; i < options.num_host_key_files; i++) { | |
711 | Key *key = sensitive_data.host_keys[i]; | |
712 | if (key != NULL && key->type == type) | |
713 | return key; | |
714 | } | |
715 | return NULL; | |
716 | } | |
717 | ||
718 | Key * | |
719 | get_hostkey_by_index(int ind) | |
720 | { | |
721 | if (ind < 0 || ind >= options.num_host_key_files) | |
722 | return (NULL); | |
723 | return (sensitive_data.host_keys[ind]); | |
724 | } | |
725 | ||
726 | int | |
727 | get_hostkey_index(Key *key) | |
728 | { | |
729 | int i; | |
730 | ||
731 | for (i = 0; i < options.num_host_key_files; i++) { | |
732 | if (key == sensitive_data.host_keys[i]) | |
733 | return (i); | |
734 | } | |
735 | return (-1); | |
736 | } | |
737 | ||
738 | /* | |
739 | * returns 1 if connection should be dropped, 0 otherwise. | |
740 | * dropping starts at connection #max_startups_begin with a probability | |
741 | * of (max_startups_rate/100). the probability increases linearly until | |
742 | * all connections are dropped for startups > max_startups | |
743 | */ | |
744 | static int | |
745 | drop_connection(int startups) | |
746 | { | |
747 | int p, r; | |
748 | ||
749 | if (startups < options.max_startups_begin) | |
750 | return 0; | |
751 | if (startups >= options.max_startups) | |
752 | return 1; | |
753 | if (options.max_startups_rate == 100) | |
754 | return 1; | |
755 | ||
756 | p = 100 - options.max_startups_rate; | |
757 | p *= startups - options.max_startups_begin; | |
758 | p /= options.max_startups - options.max_startups_begin; | |
759 | p += options.max_startups_rate; | |
760 | r = arc4random() % 100; | |
761 | ||
762 | debug("drop_connection: p %d, r %d", p, r); | |
763 | return (r < p) ? 1 : 0; | |
764 | } | |
765 | ||
766 | static void | |
767 | usage(void) | |
768 | { | |
769 | fprintf(stderr, "%s, %s\n", | |
770 | SSH_RELEASE, SSLeay_version(SSLEAY_VERSION)); | |
771 | fprintf(stderr, | |
772 | "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n" | |
773 | " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n" | |
774 | ); | |
775 | exit(1); | |
776 | } | |
777 | ||
778 | static void | |
779 | send_rexec_state(int fd, Buffer *conf) | |
780 | { | |
781 | Buffer m; | |
782 | ||
783 | debug3("%s: entering fd = %d config len %d", __func__, fd, | |
784 | buffer_len(conf)); | |
785 | ||
786 | /* | |
787 | * Protocol from reexec master to child: | |
788 | * string configuration | |
789 | * u_int ephemeral_key_follows | |
790 | * bignum e (only if ephemeral_key_follows == 1) | |
791 | * bignum n " | |
792 | * bignum d " | |
793 | * bignum iqmp " | |
794 | * bignum p " | |
795 | * bignum q " | |
796 | * string rngseed (only if OpenSSL is not self-seeded) | |
797 | */ | |
798 | buffer_init(&m); | |
799 | buffer_put_cstring(&m, buffer_ptr(conf)); | |
800 | ||
801 | if (sensitive_data.server_key != NULL && | |
802 | sensitive_data.server_key->type == KEY_RSA1) { | |
803 | buffer_put_int(&m, 1); | |
804 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->e); | |
805 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->n); | |
806 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->d); | |
807 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp); | |
808 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->p); | |
809 | buffer_put_bignum(&m, sensitive_data.server_key->rsa->q); | |
810 | } else | |
811 | buffer_put_int(&m, 0); | |
812 | ||
813 | #ifndef OPENSSL_PRNG_ONLY | |
814 | rexec_send_rng_seed(&m); | |
815 | #endif | |
816 | ||
817 | if (ssh_msg_send(fd, 0, &m) == -1) | |
818 | fatal("%s: ssh_msg_send failed", __func__); | |
819 | ||
820 | buffer_free(&m); | |
821 | ||
822 | debug3("%s: done", __func__); | |
823 | } | |
824 | ||
825 | static void | |
826 | recv_rexec_state(int fd, Buffer *conf) | |
827 | { | |
828 | Buffer m; | |
829 | char *cp; | |
830 | u_int len; | |
831 | ||
832 | debug3("%s: entering fd = %d", __func__, fd); | |
833 | ||
834 | buffer_init(&m); | |
835 | ||
836 | if (ssh_msg_recv(fd, &m) == -1) | |
837 | fatal("%s: ssh_msg_recv failed", __func__); | |
838 | if (buffer_get_char(&m) != 0) | |
839 | fatal("%s: rexec version mismatch", __func__); | |
840 | ||
841 | cp = buffer_get_string(&m, &len); | |
842 | if (conf != NULL) | |
843 | buffer_append(conf, cp, len + 1); | |
844 | xfree(cp); | |
845 | ||
846 | if (buffer_get_int(&m)) { | |
847 | if (sensitive_data.server_key != NULL) | |
848 | key_free(sensitive_data.server_key); | |
849 | sensitive_data.server_key = key_new_private(KEY_RSA1); | |
850 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->e); | |
851 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->n); | |
852 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->d); | |
853 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp); | |
854 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->p); | |
855 | buffer_get_bignum(&m, sensitive_data.server_key->rsa->q); | |
856 | rsa_generate_additional_parameters( | |
857 | sensitive_data.server_key->rsa); | |
858 | } | |
859 | ||
860 | #ifndef OPENSSL_PRNG_ONLY | |
861 | rexec_recv_rng_seed(&m); | |
862 | #endif | |
863 | ||
864 | buffer_free(&m); | |
865 | ||
866 | debug3("%s: done", __func__); | |
867 | } | |
868 | ||
869 | /* | |
870 | * Main program for the daemon. | |
871 | */ | |
872 | int | |
873 | main(int ac, char **av) | |
874 | { | |
875 | extern char *optarg; | |
876 | extern int optind; | |
877 | int opt, j, i, fdsetsz, on = 1; | |
878 | int sock_in = -1, sock_out = -1, newsock = -1; | |
879 | pid_t pid; | |
880 | socklen_t fromlen; | |
881 | fd_set *fdset; | |
882 | struct sockaddr_storage from; | |
883 | const char *remote_ip; | |
884 | int remote_port; | |
885 | FILE *f; | |
886 | struct addrinfo *ai; | |
887 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
888 | char *line; | |
889 | int listen_sock, maxfd; | |
890 | int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 }; | |
891 | int startups = 0; | |
892 | Key *key; | |
893 | Authctxt *authctxt; | |
894 | int ret, key_used = 0; | |
895 | Buffer cfg; | |
896 | ||
897 | #ifdef HAVE_SECUREWARE | |
898 | (void)set_auth_parameters(ac, av); | |
899 | #endif | |
900 | __progname = ssh_get_progname(av[0]); | |
901 | init_rng(); | |
902 | ||
903 | /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ | |
904 | saved_argc = ac; | |
905 | rexec_argc = ac; | |
906 | saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1)); | |
907 | for (i = 0; i < ac; i++) | |
908 | saved_argv[i] = xstrdup(av[i]); | |
909 | saved_argv[i] = NULL; | |
910 | ||
911 | #ifndef HAVE_SETPROCTITLE | |
912 | /* Prepare for later setproctitle emulation */ | |
913 | compat_init_setproctitle(ac, av); | |
914 | av = saved_argv; | |
915 | #endif | |
916 | ||
917 | if (geteuid() == 0 && setgroups(0, NULL) == -1) | |
918 | debug("setgroups(): %.200s", strerror(errno)); | |
919 | ||
920 | /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */ | |
921 | sanitise_stdfd(); | |
922 | ||
923 | /* Initialize configuration options to their default values. */ | |
924 | initialize_server_options(&options); | |
925 | ||
926 | /* Parse command-line arguments. */ | |
927 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) { | |
928 | switch (opt) { | |
929 | case '4': | |
930 | options.address_family = AF_INET; | |
931 | break; | |
932 | case '6': | |
933 | options.address_family = AF_INET6; | |
934 | break; | |
935 | case 'f': | |
936 | config_file_name = optarg; | |
937 | break; | |
938 | case 'd': | |
939 | if (debug_flag == 0) { | |
940 | debug_flag = 1; | |
941 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
942 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) | |
943 | options.log_level++; | |
944 | break; | |
945 | case 'D': | |
946 | no_daemon_flag = 1; | |
947 | break; | |
948 | case 'e': | |
949 | log_stderr = 1; | |
950 | break; | |
951 | case 'i': | |
952 | inetd_flag = 1; | |
953 | break; | |
954 | case 'r': | |
955 | rexec_flag = 0; | |
956 | break; | |
957 | case 'R': | |
958 | rexeced_flag = 1; | |
959 | inetd_flag = 1; | |
960 | break; | |
961 | case 'Q': | |
962 | /* ignored */ | |
963 | break; | |
964 | case 'q': | |
965 | options.log_level = SYSLOG_LEVEL_QUIET; | |
966 | break; | |
967 | case 'b': | |
968 | options.server_key_bits = atoi(optarg); | |
969 | break; | |
970 | case 'p': | |
971 | options.ports_from_cmdline = 1; | |
972 | if (options.num_ports >= MAX_PORTS) { | |
973 | fprintf(stderr, "too many ports.\n"); | |
974 | exit(1); | |
975 | } | |
976 | options.ports[options.num_ports++] = a2port(optarg); | |
977 | if (options.ports[options.num_ports-1] == 0) { | |
978 | fprintf(stderr, "Bad port number.\n"); | |
979 | exit(1); | |
980 | } | |
981 | break; | |
982 | case 'g': | |
983 | if ((options.login_grace_time = convtime(optarg)) == -1) { | |
984 | fprintf(stderr, "Invalid login grace time.\n"); | |
985 | exit(1); | |
986 | } | |
987 | break; | |
988 | case 'k': | |
989 | if ((options.key_regeneration_time = convtime(optarg)) == -1) { | |
990 | fprintf(stderr, "Invalid key regeneration interval.\n"); | |
991 | exit(1); | |
992 | } | |
993 | break; | |
994 | case 'h': | |
995 | if (options.num_host_key_files >= MAX_HOSTKEYS) { | |
996 | fprintf(stderr, "too many host keys.\n"); | |
997 | exit(1); | |
998 | } | |
999 | options.host_key_files[options.num_host_key_files++] = optarg; | |
1000 | break; | |
1001 | case 't': | |
1002 | test_flag = 1; | |
1003 | break; | |
1004 | case 'u': | |
1005 | utmp_len = atoi(optarg); | |
1006 | if (utmp_len > MAXHOSTNAMELEN) { | |
1007 | fprintf(stderr, "Invalid utmp length.\n"); | |
1008 | exit(1); | |
1009 | } | |
1010 | break; | |
1011 | case 'o': | |
1012 | line = xstrdup(optarg); | |
1013 | if (process_server_config_line(&options, line, | |
1014 | "command-line", 0) != 0) | |
1015 | exit(1); | |
1016 | xfree(line); | |
1017 | break; | |
1018 | case '?': | |
1019 | default: | |
1020 | usage(); | |
1021 | break; | |
1022 | } | |
1023 | } | |
1024 | if (rexeced_flag || inetd_flag) | |
1025 | rexec_flag = 0; | |
1026 | if (rexec_flag && (av[0] == NULL || *av[0] != '/')) | |
1027 | fatal("sshd re-exec requires execution with an absolute path"); | |
1028 | if (rexeced_flag) | |
1029 | closefrom(REEXEC_MIN_FREE_FD); | |
1030 | else | |
1031 | closefrom(REEXEC_DEVCRYPTO_RESERVED_FD); | |
1032 | ||
1033 | SSLeay_add_all_algorithms(); | |
1034 | ||
1035 | /* | |
1036 | * Force logging to stderr until we have loaded the private host | |
1037 | * key (unless started from inetd) | |
1038 | */ | |
1039 | log_init(__progname, | |
1040 | options.log_level == SYSLOG_LEVEL_NOT_SET ? | |
1041 | SYSLOG_LEVEL_INFO : options.log_level, | |
1042 | options.log_facility == SYSLOG_FACILITY_NOT_SET ? | |
1043 | SYSLOG_FACILITY_AUTH : options.log_facility, | |
1044 | log_stderr || !inetd_flag); | |
1045 | ||
1046 | /* | |
1047 | * Unset KRB5CCNAME, otherwise the user's session may inherit it from | |
1048 | * root's environment | |
1049 | */ | |
1050 | if (getenv("KRB5CCNAME") != NULL) | |
1051 | unsetenv("KRB5CCNAME"); | |
1052 | ||
1053 | #ifdef _UNICOS | |
1054 | /* Cray can define user privs drop all privs now! | |
1055 | * Not needed on PRIV_SU systems! | |
1056 | */ | |
1057 | drop_cray_privs(); | |
1058 | #endif | |
1059 | ||
1060 | sensitive_data.server_key = NULL; | |
1061 | sensitive_data.ssh1_host_key = NULL; | |
1062 | sensitive_data.have_ssh1_key = 0; | |
1063 | sensitive_data.have_ssh2_key = 0; | |
1064 | ||
1065 | /* Fetch our configuration */ | |
1066 | buffer_init(&cfg); | |
1067 | if (rexeced_flag) | |
1068 | recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg); | |
1069 | else | |
1070 | load_server_config(config_file_name, &cfg); | |
1071 | ||
1072 | parse_server_config(&options, | |
1073 | rexeced_flag ? "rexec" : config_file_name, &cfg); | |
1074 | ||
1075 | if (!rexec_flag) | |
1076 | buffer_free(&cfg); | |
1077 | ||
1078 | seed_rng(); | |
1079 | ||
1080 | /* Fill in default values for those options not explicitly set. */ | |
1081 | fill_default_server_options(&options); | |
1082 | ||
1083 | /* set default channel AF */ | |
1084 | channel_set_af(options.address_family); | |
1085 | ||
1086 | /* Check that there are no remaining arguments. */ | |
1087 | if (optind < ac) { | |
1088 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
1089 | exit(1); | |
1090 | } | |
1091 | ||
1092 | debug("sshd version %.100s", SSH_RELEASE); | |
1093 | ||
1094 | /* load private host keys */ | |
1095 | sensitive_data.host_keys = xmalloc(options.num_host_key_files * | |
1096 | sizeof(Key *)); | |
1097 | for (i = 0; i < options.num_host_key_files; i++) | |
1098 | sensitive_data.host_keys[i] = NULL; | |
1099 | ||
1100 | for (i = 0; i < options.num_host_key_files; i++) { | |
1101 | key = key_load_private(options.host_key_files[i], "", NULL); | |
1102 | sensitive_data.host_keys[i] = key; | |
1103 | if (key == NULL) { | |
1104 | error("Could not load host key: %s", | |
1105 | options.host_key_files[i]); | |
1106 | sensitive_data.host_keys[i] = NULL; | |
1107 | continue; | |
1108 | } | |
1109 | switch (key->type) { | |
1110 | case KEY_RSA1: | |
1111 | sensitive_data.ssh1_host_key = key; | |
1112 | sensitive_data.have_ssh1_key = 1; | |
1113 | break; | |
1114 | case KEY_RSA: | |
1115 | case KEY_DSA: | |
1116 | sensitive_data.have_ssh2_key = 1; | |
1117 | break; | |
1118 | } | |
1119 | debug("private host key: #%d type %d %s", i, key->type, | |
1120 | key_type(key)); | |
1121 | } | |
1122 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
1123 | logit("Disabling protocol version 1. Could not load host key"); | |
1124 | options.protocol &= ~SSH_PROTO_1; | |
1125 | } | |
1126 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
1127 | logit("Disabling protocol version 2. Could not load host key"); | |
1128 | options.protocol &= ~SSH_PROTO_2; | |
1129 | } | |
1130 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { | |
1131 | logit("sshd: no hostkeys available -- exiting."); | |
1132 | exit(1); | |
1133 | } | |
1134 | ||
1135 | /* Check certain values for sanity. */ | |
1136 | if (options.protocol & SSH_PROTO_1) { | |
1137 | if (options.server_key_bits < 512 || | |
1138 | options.server_key_bits > 32768) { | |
1139 | fprintf(stderr, "Bad server key size.\n"); | |
1140 | exit(1); | |
1141 | } | |
1142 | /* | |
1143 | * Check that server and host key lengths differ sufficiently. This | |
1144 | * is necessary to make double encryption work with rsaref. Oh, I | |
1145 | * hate software patents. I dont know if this can go? Niels | |
1146 | */ | |
1147 | if (options.server_key_bits > | |
1148 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - | |
1149 | SSH_KEY_BITS_RESERVED && options.server_key_bits < | |
1150 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1151 | SSH_KEY_BITS_RESERVED) { | |
1152 | options.server_key_bits = | |
1153 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1154 | SSH_KEY_BITS_RESERVED; | |
1155 | debug("Forcing server key to %d bits to make it differ from host key.", | |
1156 | options.server_key_bits); | |
1157 | } | |
1158 | } | |
1159 | ||
1160 | if (use_privsep) { | |
1161 | struct passwd *pw; | |
1162 | struct stat st; | |
1163 | ||
1164 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
1165 | fatal("Privilege separation user %s does not exist", | |
1166 | SSH_PRIVSEP_USER); | |
1167 | if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || | |
1168 | (S_ISDIR(st.st_mode) == 0)) | |
1169 | fatal("Missing privilege separation directory: %s", | |
1170 | _PATH_PRIVSEP_CHROOT_DIR); | |
1171 | ||
1172 | #ifdef HAVE_CYGWIN | |
1173 | if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && | |
1174 | (st.st_uid != getuid () || | |
1175 | (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) | |
1176 | #else | |
1177 | if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) | |
1178 | #endif | |
1179 | fatal("%s must be owned by root and not group or " | |
1180 | "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); | |
1181 | } | |
1182 | ||
1183 | /* Configuration looks good, so exit if in test mode. */ | |
1184 | if (test_flag) | |
1185 | exit(0); | |
1186 | ||
1187 | /* | |
1188 | * Clear out any supplemental groups we may have inherited. This | |
1189 | * prevents inadvertent creation of files with bad modes (in the | |
1190 | * portable version at least, it's certainly possible for PAM | |
1191 | * to create a file, and we can't control the code in every | |
1192 | * module which might be used). | |
1193 | */ | |
1194 | if (setgroups(0, NULL) < 0) | |
1195 | debug("setgroups() failed: %.200s", strerror(errno)); | |
1196 | ||
1197 | if (rexec_flag) { | |
1198 | rexec_argv = xmalloc(sizeof(char *) * (rexec_argc + 2)); | |
1199 | for (i = 0; i < rexec_argc; i++) { | |
1200 | debug("rexec_argv[%d]='%s'", i, saved_argv[i]); | |
1201 | rexec_argv[i] = saved_argv[i]; | |
1202 | } | |
1203 | rexec_argv[rexec_argc] = "-R"; | |
1204 | rexec_argv[rexec_argc + 1] = NULL; | |
1205 | } | |
1206 | ||
1207 | /* Initialize the log (it is reinitialized below in case we forked). */ | |
1208 | if (debug_flag && (!inetd_flag || rexeced_flag)) | |
1209 | log_stderr = 1; | |
1210 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1211 | ||
1212 | /* | |
1213 | * If not in debugging mode, and not started from inetd, disconnect | |
1214 | * from the controlling terminal, and fork. The original process | |
1215 | * exits. | |
1216 | */ | |
1217 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { | |
1218 | #ifdef TIOCNOTTY | |
1219 | int fd; | |
1220 | #endif /* TIOCNOTTY */ | |
1221 | if (daemon(0, 0) < 0) | |
1222 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1223 | ||
1224 | /* Disconnect from the controlling tty. */ | |
1225 | #ifdef TIOCNOTTY | |
1226 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); | |
1227 | if (fd >= 0) { | |
1228 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
1229 | close(fd); | |
1230 | } | |
1231 | #endif /* TIOCNOTTY */ | |
1232 | } | |
1233 | /* Reinitialize the log (because of the fork above). */ | |
1234 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1235 | ||
1236 | /* Initialize the random number generator. */ | |
1237 | arc4random_stir(); | |
1238 | ||
1239 | /* Chdir to the root directory so that the current disk can be | |
1240 | unmounted if desired. */ | |
1241 | chdir("/"); | |
1242 | ||
1243 | /* ignore SIGPIPE */ | |
1244 | signal(SIGPIPE, SIG_IGN); | |
1245 | ||
1246 | /* Start listening for a socket, unless started from inetd. */ | |
1247 | if (inetd_flag) { | |
1248 | int fd; | |
1249 | ||
1250 | startup_pipe = -1; | |
1251 | if (rexeced_flag) { | |
1252 | close(REEXEC_CONFIG_PASS_FD); | |
1253 | sock_in = sock_out = dup(STDIN_FILENO); | |
1254 | if (!debug_flag) { | |
1255 | startup_pipe = dup(REEXEC_STARTUP_PIPE_FD); | |
1256 | close(REEXEC_STARTUP_PIPE_FD); | |
1257 | } | |
1258 | } else { | |
1259 | sock_in = dup(STDIN_FILENO); | |
1260 | sock_out = dup(STDOUT_FILENO); | |
1261 | } | |
1262 | /* | |
1263 | * We intentionally do not close the descriptors 0, 1, and 2 | |
1264 | * as our code for setting the descriptors won't work if | |
1265 | * ttyfd happens to be one of those. | |
1266 | */ | |
1267 | if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { | |
1268 | dup2(fd, STDIN_FILENO); | |
1269 | dup2(fd, STDOUT_FILENO); | |
1270 | if (fd > STDOUT_FILENO) | |
1271 | close(fd); | |
1272 | } | |
1273 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); | |
1274 | if ((options.protocol & SSH_PROTO_1) && | |
1275 | sensitive_data.server_key == NULL) | |
1276 | generate_ephemeral_server_key(); | |
1277 | } else { | |
1278 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { | |
1279 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
1280 | continue; | |
1281 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
1282 | fatal("Too many listen sockets. " | |
1283 | "Enlarge MAX_LISTEN_SOCKS"); | |
1284 | if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
1285 | ntop, sizeof(ntop), strport, sizeof(strport), | |
1286 | NI_NUMERICHOST|NI_NUMERICSERV)) != 0) { | |
1287 | error("getnameinfo failed: %.100s", | |
1288 | (ret != EAI_SYSTEM) ? gai_strerror(ret) : | |
1289 | strerror(errno)); | |
1290 | continue; | |
1291 | } | |
1292 | /* Create socket for listening. */ | |
1293 | listen_sock = socket(ai->ai_family, ai->ai_socktype, | |
1294 | ai->ai_protocol); | |
1295 | if (listen_sock < 0) { | |
1296 | /* kernel may not support ipv6 */ | |
1297 | verbose("socket: %.100s", strerror(errno)); | |
1298 | continue; | |
1299 | } | |
1300 | if (set_nonblock(listen_sock) == -1) { | |
1301 | close(listen_sock); | |
1302 | continue; | |
1303 | } | |
1304 | /* | |
1305 | * Set socket options. | |
1306 | * Allow local port reuse in TIME_WAIT. | |
1307 | */ | |
1308 | if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, | |
1309 | &on, sizeof(on)) == -1) | |
1310 | error("setsockopt SO_REUSEADDR: %s", strerror(errno)); | |
1311 | ||
1312 | debug("Bind to port %s on %s.", strport, ntop); | |
1313 | ||
1314 | /* Bind the socket to the desired port. */ | |
1315 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { | |
1316 | if (!ai->ai_next) | |
1317 | error("Bind to port %s on %s failed: %.200s.", | |
1318 | strport, ntop, strerror(errno)); | |
1319 | close(listen_sock); | |
1320 | continue; | |
1321 | } | |
1322 | listen_socks[num_listen_socks] = listen_sock; | |
1323 | num_listen_socks++; | |
1324 | ||
1325 | /* Start listening on the port. */ | |
1326 | logit("Server listening on %s port %s.", ntop, strport); | |
1327 | if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) | |
1328 | fatal("listen: %.100s", strerror(errno)); | |
1329 | ||
1330 | } | |
1331 | freeaddrinfo(options.listen_addrs); | |
1332 | ||
1333 | if (!num_listen_socks) | |
1334 | fatal("Cannot bind any address."); | |
1335 | ||
1336 | if (options.protocol & SSH_PROTO_1) | |
1337 | generate_ephemeral_server_key(); | |
1338 | ||
1339 | /* | |
1340 | * Arrange to restart on SIGHUP. The handler needs | |
1341 | * listen_sock. | |
1342 | */ | |
1343 | signal(SIGHUP, sighup_handler); | |
1344 | ||
1345 | signal(SIGTERM, sigterm_handler); | |
1346 | signal(SIGQUIT, sigterm_handler); | |
1347 | ||
1348 | /* Arrange SIGCHLD to be caught. */ | |
1349 | signal(SIGCHLD, main_sigchld_handler); | |
1350 | ||
1351 | /* Write out the pid file after the sigterm handler is setup */ | |
1352 | if (!debug_flag) { | |
1353 | /* | |
1354 | * Record our pid in /var/run/sshd.pid to make it | |
1355 | * easier to kill the correct sshd. We don't want to | |
1356 | * do this before the bind above because the bind will | |
1357 | * fail if there already is a daemon, and this will | |
1358 | * overwrite any old pid in the file. | |
1359 | */ | |
1360 | f = fopen(options.pid_file, "wb"); | |
1361 | if (f == NULL) { | |
1362 | error("Couldn't create pid file \"%s\": %s", | |
1363 | options.pid_file, strerror(errno)); | |
1364 | } else { | |
1365 | fprintf(f, "%ld\n", (long) getpid()); | |
1366 | fclose(f); | |
1367 | } | |
1368 | } | |
1369 | ||
1370 | /* setup fd set for listen */ | |
1371 | fdset = NULL; | |
1372 | maxfd = 0; | |
1373 | for (i = 0; i < num_listen_socks; i++) | |
1374 | if (listen_socks[i] > maxfd) | |
1375 | maxfd = listen_socks[i]; | |
1376 | /* pipes connected to unauthenticated childs */ | |
1377 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
1378 | for (i = 0; i < options.max_startups; i++) | |
1379 | startup_pipes[i] = -1; | |
1380 | ||
1381 | /* | |
1382 | * Stay listening for connections until the system crashes or | |
1383 | * the daemon is killed with a signal. | |
1384 | */ | |
1385 | for (;;) { | |
1386 | if (received_sighup) | |
1387 | sighup_restart(); | |
1388 | if (fdset != NULL) | |
1389 | xfree(fdset); | |
1390 | fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); | |
1391 | fdset = (fd_set *)xmalloc(fdsetsz); | |
1392 | memset(fdset, 0, fdsetsz); | |
1393 | ||
1394 | for (i = 0; i < num_listen_socks; i++) | |
1395 | FD_SET(listen_socks[i], fdset); | |
1396 | for (i = 0; i < options.max_startups; i++) | |
1397 | if (startup_pipes[i] != -1) | |
1398 | FD_SET(startup_pipes[i], fdset); | |
1399 | ||
1400 | /* Wait in select until there is a connection. */ | |
1401 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); | |
1402 | if (ret < 0 && errno != EINTR) | |
1403 | error("select: %.100s", strerror(errno)); | |
1404 | if (received_sigterm) { | |
1405 | logit("Received signal %d; terminating.", | |
1406 | (int) received_sigterm); | |
1407 | close_listen_socks(); | |
1408 | unlink(options.pid_file); | |
1409 | exit(255); | |
1410 | } | |
1411 | if (key_used && key_do_regen) { | |
1412 | generate_ephemeral_server_key(); | |
1413 | key_used = 0; | |
1414 | key_do_regen = 0; | |
1415 | } | |
1416 | if (ret < 0) | |
1417 | continue; | |
1418 | ||
1419 | for (i = 0; i < options.max_startups; i++) | |
1420 | if (startup_pipes[i] != -1 && | |
1421 | FD_ISSET(startup_pipes[i], fdset)) { | |
1422 | /* | |
1423 | * the read end of the pipe is ready | |
1424 | * if the child has closed the pipe | |
1425 | * after successful authentication | |
1426 | * or if the child has died | |
1427 | */ | |
1428 | close(startup_pipes[i]); | |
1429 | startup_pipes[i] = -1; | |
1430 | startups--; | |
1431 | } | |
1432 | for (i = 0; i < num_listen_socks; i++) { | |
1433 | if (!FD_ISSET(listen_socks[i], fdset)) | |
1434 | continue; | |
1435 | fromlen = sizeof(from); | |
1436 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
1437 | &fromlen); | |
1438 | if (newsock < 0) { | |
1439 | if (errno != EINTR && errno != EWOULDBLOCK) | |
1440 | error("accept: %.100s", strerror(errno)); | |
1441 | continue; | |
1442 | } | |
1443 | if (unset_nonblock(newsock) == -1) { | |
1444 | close(newsock); | |
1445 | continue; | |
1446 | } | |
1447 | if (drop_connection(startups) == 1) { | |
1448 | debug("drop connection #%d", startups); | |
1449 | close(newsock); | |
1450 | continue; | |
1451 | } | |
1452 | if (pipe(startup_p) == -1) { | |
1453 | close(newsock); | |
1454 | continue; | |
1455 | } | |
1456 | ||
1457 | if (rexec_flag && socketpair(AF_UNIX, | |
1458 | SOCK_STREAM, 0, config_s) == -1) { | |
1459 | error("reexec socketpair: %s", | |
1460 | strerror(errno)); | |
1461 | close(newsock); | |
1462 | close(startup_p[0]); | |
1463 | close(startup_p[1]); | |
1464 | continue; | |
1465 | } | |
1466 | ||
1467 | for (j = 0; j < options.max_startups; j++) | |
1468 | if (startup_pipes[j] == -1) { | |
1469 | startup_pipes[j] = startup_p[0]; | |
1470 | if (maxfd < startup_p[0]) | |
1471 | maxfd = startup_p[0]; | |
1472 | startups++; | |
1473 | break; | |
1474 | } | |
1475 | ||
1476 | /* | |
1477 | * Got connection. Fork a child to handle it, unless | |
1478 | * we are in debugging mode. | |
1479 | */ | |
1480 | if (debug_flag) { | |
1481 | /* | |
1482 | * In debugging mode. Close the listening | |
1483 | * socket, and start processing the | |
1484 | * connection without forking. | |
1485 | */ | |
1486 | debug("Server will not fork when running in debugging mode."); | |
1487 | close_listen_socks(); | |
1488 | sock_in = newsock; | |
1489 | sock_out = newsock; | |
1490 | close(startup_p[0]); | |
1491 | close(startup_p[1]); | |
1492 | startup_pipe = -1; | |
1493 | pid = getpid(); | |
1494 | if (rexec_flag) { | |
1495 | send_rexec_state(config_s[0], | |
1496 | &cfg); | |
1497 | close(config_s[0]); | |
1498 | } | |
1499 | break; | |
1500 | } else { | |
1501 | /* | |
1502 | * Normal production daemon. Fork, and have | |
1503 | * the child process the connection. The | |
1504 | * parent continues listening. | |
1505 | */ | |
1506 | if ((pid = fork()) == 0) { | |
1507 | /* | |
1508 | * Child. Close the listening and max_startup | |
1509 | * sockets. Start using the accepted socket. | |
1510 | * Reinitialize logging (since our pid has | |
1511 | * changed). We break out of the loop to handle | |
1512 | * the connection. | |
1513 | */ | |
1514 | startup_pipe = startup_p[1]; | |
1515 | close_startup_pipes(); | |
1516 | close_listen_socks(); | |
1517 | sock_in = newsock; | |
1518 | sock_out = newsock; | |
1519 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1520 | if (rexec_flag) | |
1521 | close(config_s[0]); | |
1522 | break; | |
1523 | } | |
1524 | } | |
1525 | ||
1526 | /* Parent. Stay in the loop. */ | |
1527 | if (pid < 0) | |
1528 | error("fork: %.100s", strerror(errno)); | |
1529 | else | |
1530 | debug("Forked child %ld.", (long)pid); | |
1531 | ||
1532 | close(startup_p[1]); | |
1533 | ||
1534 | if (rexec_flag) { | |
1535 | send_rexec_state(config_s[0], &cfg); | |
1536 | close(config_s[0]); | |
1537 | close(config_s[1]); | |
1538 | } | |
1539 | ||
1540 | /* Mark that the key has been used (it was "given" to the child). */ | |
1541 | if ((options.protocol & SSH_PROTO_1) && | |
1542 | key_used == 0) { | |
1543 | /* Schedule server key regeneration alarm. */ | |
1544 | signal(SIGALRM, key_regeneration_alarm); | |
1545 | alarm(options.key_regeneration_time); | |
1546 | key_used = 1; | |
1547 | } | |
1548 | ||
1549 | arc4random_stir(); | |
1550 | ||
1551 | /* Close the new socket (the child is now taking care of it). */ | |
1552 | close(newsock); | |
1553 | } | |
1554 | /* child process check (or debug mode) */ | |
1555 | if (num_listen_socks < 0) | |
1556 | break; | |
1557 | } | |
1558 | } | |
1559 | ||
1560 | /* This is the child processing a new connection. */ | |
1561 | setproctitle("%s", "[accepted]"); | |
1562 | ||
1563 | /* | |
1564 | * Create a new session and process group since the 4.4BSD | |
1565 | * setlogin() affects the entire process group. We don't | |
1566 | * want the child to be able to affect the parent. | |
1567 | */ | |
1568 | #if !defined(SSHD_ACQUIRES_CTTY) | |
1569 | /* | |
1570 | * If setsid is called, on some platforms sshd will later acquire a | |
1571 | * controlling terminal which will result in "could not set | |
1572 | * controlling tty" errors. | |
1573 | */ | |
1574 | if (!debug_flag && !inetd_flag && setsid() < 0) | |
1575 | error("setsid: %.100s", strerror(errno)); | |
1576 | #endif | |
1577 | ||
1578 | if (rexec_flag) { | |
1579 | int fd; | |
1580 | ||
1581 | debug("rexec start in %d out %d newsock %d pipe %d sock %d", | |
1582 | sock_in, sock_out, newsock, startup_pipe, config_s[0]); | |
1583 | dup2(newsock, STDIN_FILENO); | |
1584 | dup2(STDIN_FILENO, STDOUT_FILENO); | |
1585 | if (startup_pipe == -1) | |
1586 | close(REEXEC_STARTUP_PIPE_FD); | |
1587 | else | |
1588 | dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD); | |
1589 | ||
1590 | dup2(config_s[1], REEXEC_CONFIG_PASS_FD); | |
1591 | close(config_s[1]); | |
1592 | if (startup_pipe != -1) | |
1593 | close(startup_pipe); | |
1594 | ||
1595 | execv(rexec_argv[0], rexec_argv); | |
1596 | ||
1597 | /* Reexec has failed, fall back and continue */ | |
1598 | error("rexec of %s failed: %s", rexec_argv[0], strerror(errno)); | |
1599 | recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL); | |
1600 | log_init(__progname, options.log_level, | |
1601 | options.log_facility, log_stderr); | |
1602 | ||
1603 | /* Clean up fds */ | |
1604 | startup_pipe = REEXEC_STARTUP_PIPE_FD; | |
1605 | close(config_s[1]); | |
1606 | close(REEXEC_CONFIG_PASS_FD); | |
1607 | newsock = sock_out = sock_in = dup(STDIN_FILENO); | |
1608 | if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) { | |
1609 | dup2(fd, STDIN_FILENO); | |
1610 | dup2(fd, STDOUT_FILENO); | |
1611 | if (fd > STDERR_FILENO) | |
1612 | close(fd); | |
1613 | } | |
1614 | debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d", | |
1615 | sock_in, sock_out, newsock, startup_pipe, config_s[0]); | |
1616 | } | |
1617 | ||
1618 | /* | |
1619 | * Disable the key regeneration alarm. We will not regenerate the | |
1620 | * key since we are no longer in a position to give it to anyone. We | |
1621 | * will not restart on SIGHUP since it no longer makes sense. | |
1622 | */ | |
1623 | alarm(0); | |
1624 | signal(SIGALRM, SIG_DFL); | |
1625 | signal(SIGHUP, SIG_DFL); | |
1626 | signal(SIGTERM, SIG_DFL); | |
1627 | signal(SIGQUIT, SIG_DFL); | |
1628 | signal(SIGCHLD, SIG_DFL); | |
1629 | signal(SIGINT, SIG_DFL); | |
1630 | ||
1631 | /* | |
1632 | * Register our connection. This turns encryption off because we do | |
1633 | * not have a key. | |
1634 | */ | |
1635 | packet_set_connection(sock_in, sock_out); | |
1636 | packet_set_server(); | |
1637 | ||
1638 | /* Set SO_KEEPALIVE if requested. */ | |
1639 | if (options.tcp_keep_alive && packet_connection_is_on_socket() && | |
1640 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0) | |
1641 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1642 | ||
1643 | if ((remote_port = get_remote_port()) < 0) { | |
1644 | debug("get_remote_port failed"); | |
1645 | cleanup_exit(255); | |
1646 | } | |
1647 | ||
1648 | /* | |
1649 | * We use get_canonical_hostname with usedns = 0 instead of | |
1650 | * get_remote_ipaddr here so IP options will be checked. | |
1651 | */ | |
1652 | remote_ip = get_canonical_hostname(0); | |
1653 | ||
1654 | #ifdef SSH_AUDIT_EVENTS | |
1655 | audit_connection_from(remote_ip, remote_port); | |
1656 | #endif | |
1657 | #ifdef LIBWRAP | |
1658 | /* Check whether logins are denied from this host. */ | |
1659 | if (packet_connection_is_on_socket()) { | |
1660 | struct request_info req; | |
1661 | ||
1662 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); | |
1663 | fromhost(&req); | |
1664 | ||
1665 | if (!hosts_access(&req)) { | |
1666 | debug("Connection refused by tcp wrapper"); | |
1667 | refuse(&req); | |
1668 | /* NOTREACHED */ | |
1669 | fatal("libwrap refuse returns"); | |
1670 | } | |
1671 | } | |
1672 | #endif /* LIBWRAP */ | |
1673 | ||
1674 | /* Log the connection. */ | |
1675 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
1676 | ||
1677 | /* | |
1678 | * We don't want to listen forever unless the other side | |
1679 | * successfully authenticates itself. So we set up an alarm which is | |
1680 | * cleared after successful authentication. A limit of zero | |
1681 | * indicates no limit. Note that we don't set the alarm in debugging | |
1682 | * mode; it is just annoying to have the server exit just when you | |
1683 | * are about to discover the bug. | |
1684 | */ | |
1685 | signal(SIGALRM, grace_alarm_handler); | |
1686 | if (!debug_flag) | |
1687 | alarm(options.login_grace_time); | |
1688 | ||
1689 | sshd_exchange_identification(sock_in, sock_out); | |
1690 | ||
1691 | packet_set_nonblocking(); | |
1692 | ||
1693 | /* allocate authentication context */ | |
1694 | authctxt = xmalloc(sizeof(*authctxt)); | |
1695 | memset(authctxt, 0, sizeof(*authctxt)); | |
1696 | ||
1697 | authctxt->loginmsg = &loginmsg; | |
1698 | ||
1699 | /* XXX global for cleanup, access from other modules */ | |
1700 | the_authctxt = authctxt; | |
1701 | ||
1702 | /* prepare buffer to collect messages to display to user after login */ | |
1703 | buffer_init(&loginmsg); | |
1704 | ||
1705 | if (use_privsep) | |
1706 | if (privsep_preauth(authctxt) == 1) | |
1707 | goto authenticated; | |
1708 | ||
1709 | /* perform the key exchange */ | |
1710 | /* authenticate user and start session */ | |
1711 | if (compat20) { | |
1712 | do_ssh2_kex(); | |
1713 | do_authentication2(authctxt); | |
1714 | } else { | |
1715 | do_ssh1_kex(); | |
1716 | do_authentication(authctxt); | |
1717 | } | |
1718 | /* | |
1719 | * If we use privilege separation, the unprivileged child transfers | |
1720 | * the current keystate and exits | |
1721 | */ | |
1722 | if (use_privsep) { | |
1723 | mm_send_keystate(pmonitor); | |
1724 | exit(0); | |
1725 | } | |
1726 | ||
1727 | authenticated: | |
1728 | /* | |
1729 | * Cancel the alarm we set to limit the time taken for | |
1730 | * authentication. | |
1731 | */ | |
1732 | alarm(0); | |
1733 | signal(SIGALRM, SIG_DFL); | |
1734 | if (startup_pipe != -1) { | |
1735 | close(startup_pipe); | |
1736 | startup_pipe = -1; | |
1737 | } | |
1738 | ||
1739 | #ifdef SSH_AUDIT_EVENTS | |
1740 | audit_event(SSH_AUTH_SUCCESS); | |
1741 | #endif | |
1742 | ||
1743 | /* | |
1744 | * In privilege separation, we fork another child and prepare | |
1745 | * file descriptor passing. | |
1746 | */ | |
1747 | if (use_privsep) { | |
1748 | privsep_postauth(authctxt); | |
1749 | /* the monitor process [priv] will not return */ | |
1750 | if (!compat20) | |
1751 | destroy_sensitive_data(); | |
1752 | } | |
1753 | ||
1754 | /* Start session. */ | |
1755 | do_authenticated(authctxt); | |
1756 | ||
1757 | /* The connection has been terminated. */ | |
1758 | verbose("Closing connection to %.100s", remote_ip); | |
1759 | ||
1760 | #ifdef USE_PAM | |
1761 | if (options.use_pam) | |
1762 | finish_pam(); | |
1763 | #endif /* USE_PAM */ | |
1764 | ||
1765 | #ifdef SSH_AUDIT_EVENTS | |
1766 | PRIVSEP(audit_event(SSH_CONNECTION_CLOSE)); | |
1767 | #endif | |
1768 | ||
1769 | packet_close(); | |
1770 | ||
1771 | if (use_privsep) | |
1772 | mm_terminate(); | |
1773 | ||
1774 | exit(0); | |
1775 | } | |
1776 | ||
1777 | /* | |
1778 | * Decrypt session_key_int using our private server key and private host key | |
1779 | * (key with larger modulus first). | |
1780 | */ | |
1781 | int | |
1782 | ssh1_session_key(BIGNUM *session_key_int) | |
1783 | { | |
1784 | int rsafail = 0; | |
1785 | ||
1786 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { | |
1787 | /* Server key has bigger modulus. */ | |
1788 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < | |
1789 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1790 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1791 | get_remote_ipaddr(), | |
1792 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1793 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1794 | SSH_KEY_BITS_RESERVED); | |
1795 | } | |
1796 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1797 | sensitive_data.server_key->rsa) <= 0) | |
1798 | rsafail++; | |
1799 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1800 | sensitive_data.ssh1_host_key->rsa) <= 0) | |
1801 | rsafail++; | |
1802 | } else { | |
1803 | /* Host key has bigger modulus (or they are equal). */ | |
1804 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < | |
1805 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1806 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1807 | get_remote_ipaddr(), | |
1808 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1809 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1810 | SSH_KEY_BITS_RESERVED); | |
1811 | } | |
1812 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1813 | sensitive_data.ssh1_host_key->rsa) < 0) | |
1814 | rsafail++; | |
1815 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1816 | sensitive_data.server_key->rsa) < 0) | |
1817 | rsafail++; | |
1818 | } | |
1819 | return (rsafail); | |
1820 | } | |
1821 | /* | |
1822 | * SSH1 key exchange | |
1823 | */ | |
1824 | static void | |
1825 | do_ssh1_kex(void) | |
1826 | { | |
1827 | int i, len; | |
1828 | int rsafail = 0; | |
1829 | BIGNUM *session_key_int; | |
1830 | u_char session_key[SSH_SESSION_KEY_LENGTH]; | |
1831 | u_char cookie[8]; | |
1832 | u_int cipher_type, auth_mask, protocol_flags; | |
1833 | u_int32_t rnd = 0; | |
1834 | ||
1835 | /* | |
1836 | * Generate check bytes that the client must send back in the user | |
1837 | * packet in order for it to be accepted; this is used to defy ip | |
1838 | * spoofing attacks. Note that this only works against somebody | |
1839 | * doing IP spoofing from a remote machine; any machine on the local | |
1840 | * network can still see outgoing packets and catch the random | |
1841 | * cookie. This only affects rhosts authentication, and this is one | |
1842 | * of the reasons why it is inherently insecure. | |
1843 | */ | |
1844 | for (i = 0; i < 8; i++) { | |
1845 | if (i % 4 == 0) | |
1846 | rnd = arc4random(); | |
1847 | cookie[i] = rnd & 0xff; | |
1848 | rnd >>= 8; | |
1849 | } | |
1850 | ||
1851 | /* | |
1852 | * Send our public key. We include in the packet 64 bits of random | |
1853 | * data that must be matched in the reply in order to prevent IP | |
1854 | * spoofing. | |
1855 | */ | |
1856 | packet_start(SSH_SMSG_PUBLIC_KEY); | |
1857 | for (i = 0; i < 8; i++) | |
1858 | packet_put_char(cookie[i]); | |
1859 | ||
1860 | /* Store our public server RSA key. */ | |
1861 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); | |
1862 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1863 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
1864 | ||
1865 | /* Store our public host RSA key. */ | |
1866 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
1867 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1868 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
1869 | ||
1870 | /* Put protocol flags. */ | |
1871 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1872 | ||
1873 | /* Declare which ciphers we support. */ | |
1874 | packet_put_int(cipher_mask_ssh1(0)); | |
1875 | ||
1876 | /* Declare supported authentication types. */ | |
1877 | auth_mask = 0; | |
1878 | if (options.rhosts_rsa_authentication) | |
1879 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1880 | if (options.rsa_authentication) | |
1881 | auth_mask |= 1 << SSH_AUTH_RSA; | |
1882 | if (options.challenge_response_authentication == 1) | |
1883 | auth_mask |= 1 << SSH_AUTH_TIS; | |
1884 | if (options.password_authentication) | |
1885 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1886 | packet_put_int(auth_mask); | |
1887 | ||
1888 | /* Send the packet and wait for it to be sent. */ | |
1889 | packet_send(); | |
1890 | packet_write_wait(); | |
1891 | ||
1892 | debug("Sent %d bit server key and %d bit host key.", | |
1893 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1894 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
1895 | ||
1896 | /* Read clients reply (cipher type and session key). */ | |
1897 | packet_read_expect(SSH_CMSG_SESSION_KEY); | |
1898 | ||
1899 | /* Get cipher type and check whether we accept this. */ | |
1900 | cipher_type = packet_get_char(); | |
1901 | ||
1902 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) | |
1903 | packet_disconnect("Warning: client selects unsupported cipher."); | |
1904 | ||
1905 | /* Get check bytes from the packet. These must match those we | |
1906 | sent earlier with the public key packet. */ | |
1907 | for (i = 0; i < 8; i++) | |
1908 | if (cookie[i] != packet_get_char()) | |
1909 | packet_disconnect("IP Spoofing check bytes do not match."); | |
1910 | ||
1911 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1912 | ||
1913 | /* Get the encrypted integer. */ | |
1914 | if ((session_key_int = BN_new()) == NULL) | |
1915 | fatal("do_ssh1_kex: BN_new failed"); | |
1916 | packet_get_bignum(session_key_int); | |
1917 | ||
1918 | protocol_flags = packet_get_int(); | |
1919 | packet_set_protocol_flags(protocol_flags); | |
1920 | packet_check_eom(); | |
1921 | ||
1922 | /* Decrypt session_key_int using host/server keys */ | |
1923 | rsafail = PRIVSEP(ssh1_session_key(session_key_int)); | |
1924 | ||
1925 | /* | |
1926 | * Extract session key from the decrypted integer. The key is in the | |
1927 | * least significant 256 bits of the integer; the first byte of the | |
1928 | * key is in the highest bits. | |
1929 | */ | |
1930 | if (!rsafail) { | |
1931 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
1932 | len = BN_num_bytes(session_key_int); | |
1933 | if (len < 0 || (u_int)len > sizeof(session_key)) { | |
1934 | error("do_connection: bad session key len from %s: " | |
1935 | "session_key_int %d > sizeof(session_key) %lu", | |
1936 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); | |
1937 | rsafail++; | |
1938 | } else { | |
1939 | memset(session_key, 0, sizeof(session_key)); | |
1940 | BN_bn2bin(session_key_int, | |
1941 | session_key + sizeof(session_key) - len); | |
1942 | ||
1943 | derive_ssh1_session_id( | |
1944 | sensitive_data.ssh1_host_key->rsa->n, | |
1945 | sensitive_data.server_key->rsa->n, | |
1946 | cookie, session_id); | |
1947 | /* | |
1948 | * Xor the first 16 bytes of the session key with the | |
1949 | * session id. | |
1950 | */ | |
1951 | for (i = 0; i < 16; i++) | |
1952 | session_key[i] ^= session_id[i]; | |
1953 | } | |
1954 | } | |
1955 | if (rsafail) { | |
1956 | int bytes = BN_num_bytes(session_key_int); | |
1957 | u_char *buf = xmalloc(bytes); | |
1958 | MD5_CTX md; | |
1959 | ||
1960 | logit("do_connection: generating a fake encryption key"); | |
1961 | BN_bn2bin(session_key_int, buf); | |
1962 | MD5_Init(&md); | |
1963 | MD5_Update(&md, buf, bytes); | |
1964 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1965 | MD5_Final(session_key, &md); | |
1966 | MD5_Init(&md); | |
1967 | MD5_Update(&md, session_key, 16); | |
1968 | MD5_Update(&md, buf, bytes); | |
1969 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1970 | MD5_Final(session_key + 16, &md); | |
1971 | memset(buf, 0, bytes); | |
1972 | xfree(buf); | |
1973 | for (i = 0; i < 16; i++) | |
1974 | session_id[i] = session_key[i] ^ session_key[i + 16]; | |
1975 | } | |
1976 | /* Destroy the private and public keys. No longer. */ | |
1977 | destroy_sensitive_data(); | |
1978 | ||
1979 | if (use_privsep) | |
1980 | mm_ssh1_session_id(session_id); | |
1981 | ||
1982 | /* Destroy the decrypted integer. It is no longer needed. */ | |
1983 | BN_clear_free(session_key_int); | |
1984 | ||
1985 | /* Set the session key. From this on all communications will be encrypted. */ | |
1986 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1987 | ||
1988 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1989 | memset(session_key, 0, sizeof(session_key)); | |
1990 | ||
1991 | debug("Received session key; encryption turned on."); | |
1992 | ||
1993 | /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ | |
1994 | packet_start(SSH_SMSG_SUCCESS); | |
1995 | packet_send(); | |
1996 | packet_write_wait(); | |
1997 | } | |
1998 | ||
1999 | /* | |
2000 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
2001 | */ | |
2002 | static void | |
2003 | do_ssh2_kex(void) | |
2004 | { | |
2005 | Kex *kex; | |
2006 | ||
2007 | if (options.ciphers != NULL) { | |
2008 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
2009 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; | |
2010 | } | |
2011 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
2012 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); | |
2013 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
2014 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); | |
2015 | ||
2016 | if (options.macs != NULL) { | |
2017 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
2018 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
2019 | } | |
2020 | if (options.compression == COMP_NONE) { | |
2021 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
2022 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
2023 | } else if (options.compression == COMP_DELAYED) { | |
2024 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
2025 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com"; | |
2026 | } | |
2027 | ||
2028 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); | |
2029 | ||
2030 | /* start key exchange */ | |
2031 | kex = kex_setup(myproposal); | |
2032 | kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; | |
2033 | kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; | |
2034 | kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; | |
2035 | kex->server = 1; | |
2036 | kex->client_version_string=client_version_string; | |
2037 | kex->server_version_string=server_version_string; | |
2038 | kex->load_host_key=&get_hostkey_by_type; | |
2039 | kex->host_key_index=&get_hostkey_index; | |
2040 | ||
2041 | xxx_kex = kex; | |
2042 | ||
2043 | dispatch_run(DISPATCH_BLOCK, &kex->done, kex); | |
2044 | ||
2045 | session_id2 = kex->session_id; | |
2046 | session_id2_len = kex->session_id_len; | |
2047 | ||
2048 | #ifdef DEBUG_KEXDH | |
2049 | /* send 1st encrypted/maced/compressed message */ | |
2050 | packet_start(SSH2_MSG_IGNORE); | |
2051 | packet_put_cstring("markus"); | |
2052 | packet_send(); | |
2053 | packet_write_wait(); | |
2054 | #endif | |
2055 | debug("KEX done"); | |
2056 | } | |
2057 | ||
2058 | /* server specific fatal cleanup */ | |
2059 | void | |
2060 | cleanup_exit(int i) | |
2061 | { | |
2062 | if (the_authctxt) | |
2063 | do_cleanup(the_authctxt); | |
2064 | #ifdef SSH_AUDIT_EVENTS | |
2065 | /* done after do_cleanup so it can cancel the PAM auth 'thread' */ | |
2066 | if (!use_privsep || mm_is_monitor()) | |
2067 | audit_event(SSH_CONNECTION_ABANDON); | |
2068 | #endif | |
2069 | _exit(i); | |
2070 | } |