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3c0ef626 | 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: | |
2980ea68 | 18 | * Privilege Separation: |
3c0ef626 | 19 | * |
2980ea68 | 20 | * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. |
21 | * Copyright (c) 2002 Niels Provos. All rights reserved. | |
3c0ef626 | 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" | |
ff2d7a98 | 45 | RCSID("$OpenBSD: sshd.c,v 1.251 2002/06/25 18:51:04 markus Exp $"); |
3c0ef626 | 46 | |
47 | #include <openssl/dh.h> | |
48 | #include <openssl/bn.h> | |
1e608e42 | 49 | #include <openssl/md5.h> |
2980ea68 | 50 | #include <openssl/rand.h> |
51 | #ifdef HAVE_SECUREWARE | |
52 | #include <sys/security.h> | |
53 | #include <prot.h> | |
54 | #endif | |
3c0ef626 | 55 | |
56 | #include "ssh.h" | |
57 | #include "ssh1.h" | |
58 | #include "ssh2.h" | |
59 | #include "xmalloc.h" | |
60 | #include "rsa.h" | |
61 | #include "sshpty.h" | |
62 | #include "packet.h" | |
63 | #include "mpaux.h" | |
64 | #include "log.h" | |
65 | #include "servconf.h" | |
66 | #include "uidswap.h" | |
67 | #include "compat.h" | |
68 | #include "buffer.h" | |
69 | #include "cipher.h" | |
70 | #include "kex.h" | |
71 | #include "key.h" | |
72 | #include "dh.h" | |
73 | #include "myproposal.h" | |
74 | #include "authfile.h" | |
75 | #include "pathnames.h" | |
76 | #include "atomicio.h" | |
77 | #include "canohost.h" | |
78 | #include "auth.h" | |
79 | #include "misc.h" | |
80 | #include "dispatch.h" | |
81 | #include "channels.h" | |
2980ea68 | 82 | #include "session.h" |
83 | #include "monitor_mm.h" | |
84 | #include "monitor.h" | |
85 | #include "monitor_wrap.h" | |
86 | #include "monitor_fdpass.h" | |
3c0ef626 | 87 | |
5598e598 | 88 | #ifdef GSSAPI |
89 | #include "ssh-gss.h" | |
90 | #endif | |
91 | ||
0b582e46 | 92 | #ifdef GSSAPI |
93 | #include <openssl/md5.h> | |
94 | #include "bufaux.h" | |
95 | #endif /* GSSAPI */ | |
0b582e46 | 96 | |
3c0ef626 | 97 | #ifdef LIBWRAP |
98 | #include <tcpd.h> | |
99 | #include <syslog.h> | |
100 | int allow_severity = LOG_INFO; | |
101 | int deny_severity = LOG_WARNING; | |
102 | #endif /* LIBWRAP */ | |
103 | ||
104 | #ifndef O_NOCTTY | |
105 | #define O_NOCTTY 0 | |
106 | #endif | |
107 | ||
108 | #ifdef HAVE___PROGNAME | |
109 | extern char *__progname; | |
110 | #else | |
111 | char *__progname; | |
112 | #endif | |
113 | ||
114 | /* Server configuration options. */ | |
115 | ServerOptions options; | |
116 | ||
117 | /* Name of the server configuration file. */ | |
ae43c103 | 118 | char *config_file_name; |
3c0ef626 | 119 | |
120 | /* | |
121 | * Flag indicating whether IPv4 or IPv6. This can be set on the command line. | |
122 | * Default value is AF_UNSPEC means both IPv4 and IPv6. | |
123 | */ | |
124 | #ifdef IPV4_DEFAULT | |
125 | int IPv4or6 = AF_INET; | |
126 | #else | |
127 | int IPv4or6 = AF_UNSPEC; | |
128 | #endif | |
129 | ||
130 | /* | |
131 | * Debug mode flag. This can be set on the command line. If debug | |
132 | * mode is enabled, extra debugging output will be sent to the system | |
133 | * log, the daemon will not go to background, and will exit after processing | |
134 | * the first connection. | |
135 | */ | |
136 | int debug_flag = 0; | |
137 | ||
138 | /* Flag indicating that the daemon should only test the configuration and keys. */ | |
139 | int test_flag = 0; | |
140 | ||
141 | /* Flag indicating that the daemon is being started from inetd. */ | |
142 | int inetd_flag = 0; | |
143 | ||
144 | /* Flag indicating that sshd should not detach and become a daemon. */ | |
145 | int no_daemon_flag = 0; | |
146 | ||
147 | /* debug goes to stderr unless inetd_flag is set */ | |
148 | int log_stderr = 0; | |
149 | ||
150 | /* Saved arguments to main(). */ | |
151 | char **saved_argv; | |
152 | int saved_argc; | |
153 | ||
154 | /* | |
155 | * The sockets that the server is listening; this is used in the SIGHUP | |
156 | * signal handler. | |
157 | */ | |
158 | #define MAX_LISTEN_SOCKS 16 | |
159 | int listen_socks[MAX_LISTEN_SOCKS]; | |
160 | int num_listen_socks = 0; | |
161 | ||
162 | /* | |
163 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
164 | * sshd will skip the version-number exchange | |
165 | */ | |
166 | char *client_version_string = NULL; | |
167 | char *server_version_string = NULL; | |
168 | ||
169 | /* for rekeying XXX fixme */ | |
170 | Kex *xxx_kex; | |
171 | ||
172 | /* | |
173 | * Any really sensitive data in the application is contained in this | |
174 | * structure. The idea is that this structure could be locked into memory so | |
175 | * that the pages do not get written into swap. However, there are some | |
176 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
177 | * have access to the internals of them, and locking just the structure is | |
178 | * not very useful. Currently, memory locking is not implemented. | |
179 | */ | |
180 | struct { | |
181 | Key *server_key; /* ephemeral server key */ | |
182 | Key *ssh1_host_key; /* ssh1 host key */ | |
183 | Key **host_keys; /* all private host keys */ | |
184 | int have_ssh1_key; | |
185 | int have_ssh2_key; | |
186 | u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; | |
187 | } sensitive_data; | |
188 | ||
189 | /* | |
190 | * Flag indicating whether the RSA server key needs to be regenerated. | |
191 | * Is set in the SIGALRM handler and cleared when the key is regenerated. | |
192 | */ | |
1e608e42 | 193 | static volatile sig_atomic_t key_do_regen = 0; |
3c0ef626 | 194 | |
195 | /* This is set to true when a signal is received. */ | |
1e608e42 | 196 | static volatile sig_atomic_t received_sighup = 0; |
197 | static volatile sig_atomic_t received_sigterm = 0; | |
3c0ef626 | 198 | |
199 | /* session identifier, used by RSA-auth */ | |
200 | u_char session_id[16]; | |
201 | ||
202 | /* same for ssh2 */ | |
203 | u_char *session_id2 = NULL; | |
204 | int session_id2_len = 0; | |
205 | ||
206 | /* record remote hostname or ip */ | |
207 | u_int utmp_len = MAXHOSTNAMELEN; | |
208 | ||
1e608e42 | 209 | /* options.max_startup sized array of fd ints */ |
210 | int *startup_pipes = NULL; | |
211 | int startup_pipe; /* in child */ | |
212 | ||
2980ea68 | 213 | /* variables used for privilege separation */ |
214 | extern struct monitor *pmonitor; | |
215 | extern int use_privsep; | |
216 | ||
3c0ef626 | 217 | /* Prototypes for various functions defined later in this file. */ |
218 | void destroy_sensitive_data(void); | |
2980ea68 | 219 | void demote_sensitive_data(void); |
3c0ef626 | 220 | |
221 | static void do_ssh1_kex(void); | |
222 | static void do_ssh2_kex(void); | |
223 | ||
224 | /* | |
225 | * Close all listening sockets | |
226 | */ | |
227 | static void | |
228 | close_listen_socks(void) | |
229 | { | |
230 | int i; | |
ff2d7a98 | 231 | |
3c0ef626 | 232 | for (i = 0; i < num_listen_socks; i++) |
233 | close(listen_socks[i]); | |
234 | num_listen_socks = -1; | |
235 | } | |
236 | ||
1e608e42 | 237 | static void |
238 | close_startup_pipes(void) | |
239 | { | |
240 | int i; | |
ff2d7a98 | 241 | |
1e608e42 | 242 | if (startup_pipes) |
243 | for (i = 0; i < options.max_startups; i++) | |
244 | if (startup_pipes[i] != -1) | |
245 | close(startup_pipes[i]); | |
246 | } | |
247 | ||
3c0ef626 | 248 | /* |
249 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
250 | * the effect is to reread the configuration file (and to regenerate | |
251 | * the server key). | |
252 | */ | |
253 | static void | |
254 | sighup_handler(int sig) | |
255 | { | |
1e608e42 | 256 | int save_errno = errno; |
257 | ||
3c0ef626 | 258 | received_sighup = 1; |
259 | signal(SIGHUP, sighup_handler); | |
1e608e42 | 260 | errno = save_errno; |
3c0ef626 | 261 | } |
262 | ||
263 | /* | |
264 | * Called from the main program after receiving SIGHUP. | |
265 | * Restarts the server. | |
266 | */ | |
267 | static void | |
268 | sighup_restart(void) | |
269 | { | |
270 | log("Received SIGHUP; restarting."); | |
271 | close_listen_socks(); | |
1e608e42 | 272 | close_startup_pipes(); |
3c0ef626 | 273 | execv(saved_argv[0], saved_argv); |
ff2d7a98 | 274 | log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], |
275 | strerror(errno)); | |
3c0ef626 | 276 | exit(1); |
277 | } | |
278 | ||
279 | /* | |
280 | * Generic signal handler for terminating signals in the master daemon. | |
281 | */ | |
282 | static void | |
283 | sigterm_handler(int sig) | |
284 | { | |
285 | received_sigterm = sig; | |
286 | } | |
287 | ||
288 | /* | |
289 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
290 | * reap any zombies left by exited children. | |
291 | */ | |
292 | static void | |
293 | main_sigchld_handler(int sig) | |
294 | { | |
295 | int save_errno = errno; | |
ff2d7a98 | 296 | pid_t pid; |
3c0ef626 | 297 | int status; |
298 | ||
2980ea68 | 299 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || |
300 | (pid < 0 && errno == EINTR)) | |
3c0ef626 | 301 | ; |
302 | ||
303 | signal(SIGCHLD, main_sigchld_handler); | |
304 | errno = save_errno; | |
305 | } | |
306 | ||
307 | /* | |
308 | * Signal handler for the alarm after the login grace period has expired. | |
309 | */ | |
310 | static void | |
311 | grace_alarm_handler(int sig) | |
312 | { | |
313 | /* XXX no idea how fix this signal handler */ | |
314 | ||
315 | /* Close the connection. */ | |
316 | packet_close(); | |
317 | ||
318 | /* Log error and exit. */ | |
319 | fatal("Timeout before authentication for %s.", get_remote_ipaddr()); | |
320 | } | |
321 | ||
322 | /* | |
323 | * Signal handler for the key regeneration alarm. Note that this | |
324 | * alarm only occurs in the daemon waiting for connections, and it does not | |
325 | * do anything with the private key or random state before forking. | |
326 | * Thus there should be no concurrency control/asynchronous execution | |
327 | * problems. | |
328 | */ | |
329 | static void | |
330 | generate_ephemeral_server_key(void) | |
331 | { | |
332 | u_int32_t rand = 0; | |
333 | int i; | |
334 | ||
335 | verbose("Generating %s%d bit RSA key.", | |
336 | sensitive_data.server_key ? "new " : "", options.server_key_bits); | |
337 | if (sensitive_data.server_key != NULL) | |
338 | key_free(sensitive_data.server_key); | |
339 | sensitive_data.server_key = key_generate(KEY_RSA1, | |
340 | options.server_key_bits); | |
341 | verbose("RSA key generation complete."); | |
342 | ||
343 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
344 | if (i % 4 == 0) | |
345 | rand = arc4random(); | |
346 | sensitive_data.ssh1_cookie[i] = rand & 0xff; | |
347 | rand >>= 8; | |
348 | } | |
349 | arc4random_stir(); | |
350 | } | |
351 | ||
352 | static void | |
353 | key_regeneration_alarm(int sig) | |
354 | { | |
355 | int save_errno = errno; | |
ff2d7a98 | 356 | |
3c0ef626 | 357 | signal(SIGALRM, SIG_DFL); |
358 | errno = save_errno; | |
359 | key_do_regen = 1; | |
360 | } | |
361 | ||
362 | static void | |
363 | sshd_exchange_identification(int sock_in, int sock_out) | |
364 | { | |
365 | int i, mismatch; | |
366 | int remote_major, remote_minor; | |
367 | int major, minor; | |
368 | char *s; | |
369 | char buf[256]; /* Must not be larger than remote_version. */ | |
370 | char remote_version[256]; /* Must be at least as big as buf. */ | |
371 | ||
372 | if ((options.protocol & SSH_PROTO_1) && | |
373 | (options.protocol & SSH_PROTO_2)) { | |
374 | major = PROTOCOL_MAJOR_1; | |
375 | minor = 99; | |
376 | } else if (options.protocol & SSH_PROTO_2) { | |
377 | major = PROTOCOL_MAJOR_2; | |
378 | minor = PROTOCOL_MINOR_2; | |
379 | } else { | |
380 | major = PROTOCOL_MAJOR_1; | |
381 | minor = PROTOCOL_MINOR_1; | |
382 | } | |
383 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
384 | server_version_string = xstrdup(buf); | |
385 | ||
386 | if (client_version_string == NULL) { | |
387 | /* Send our protocol version identification. */ | |
ff2d7a98 | 388 | if (atomicio(write, sock_out, server_version_string, |
389 | strlen(server_version_string)) | |
3c0ef626 | 390 | != strlen(server_version_string)) { |
391 | log("Could not write ident string to %s", get_remote_ipaddr()); | |
392 | fatal_cleanup(); | |
393 | } | |
394 | ||
ff2d7a98 | 395 | /* Read other sides version identification. */ |
3c0ef626 | 396 | memset(buf, 0, sizeof(buf)); |
397 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
398 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { | |
399 | log("Did not receive identification string from %s", | |
400 | get_remote_ipaddr()); | |
401 | fatal_cleanup(); | |
402 | } | |
403 | if (buf[i] == '\r') { | |
404 | buf[i] = 0; | |
405 | /* Kludge for F-Secure Macintosh < 1.0.2 */ | |
406 | if (i == 12 && | |
407 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
408 | break; | |
409 | continue; | |
410 | } | |
411 | if (buf[i] == '\n') { | |
412 | buf[i] = 0; | |
413 | break; | |
414 | } | |
415 | } | |
416 | buf[sizeof(buf) - 1] = 0; | |
417 | client_version_string = xstrdup(buf); | |
418 | } | |
419 | ||
420 | /* | |
421 | * Check that the versions match. In future this might accept | |
422 | * several versions and set appropriate flags to handle them. | |
423 | */ | |
424 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
425 | &remote_major, &remote_minor, remote_version) != 3) { | |
426 | s = "Protocol mismatch.\n"; | |
427 | (void) atomicio(write, sock_out, s, strlen(s)); | |
428 | close(sock_in); | |
429 | close(sock_out); | |
430 | log("Bad protocol version identification '%.100s' from %s", | |
431 | client_version_string, get_remote_ipaddr()); | |
432 | fatal_cleanup(); | |
433 | } | |
434 | debug("Client protocol version %d.%d; client software version %.100s", | |
1e608e42 | 435 | remote_major, remote_minor, remote_version); |
3c0ef626 | 436 | |
437 | compat_datafellows(remote_version); | |
438 | ||
439 | if (datafellows & SSH_BUG_SCANNER) { | |
440 | log("scanned from %s with %s. Don't panic.", | |
441 | get_remote_ipaddr(), client_version_string); | |
442 | fatal_cleanup(); | |
443 | } | |
444 | ||
445 | mismatch = 0; | |
1e608e42 | 446 | switch (remote_major) { |
3c0ef626 | 447 | case 1: |
448 | if (remote_minor == 99) { | |
449 | if (options.protocol & SSH_PROTO_2) | |
450 | enable_compat20(); | |
451 | else | |
452 | mismatch = 1; | |
453 | break; | |
454 | } | |
455 | if (!(options.protocol & SSH_PROTO_1)) { | |
456 | mismatch = 1; | |
457 | break; | |
458 | } | |
459 | if (remote_minor < 3) { | |
460 | packet_disconnect("Your ssh version is too old and " | |
461 | "is no longer supported. Please install a newer version."); | |
462 | } else if (remote_minor == 3) { | |
463 | /* note that this disables agent-forwarding */ | |
464 | enable_compat13(); | |
465 | } | |
466 | break; | |
467 | case 2: | |
468 | if (options.protocol & SSH_PROTO_2) { | |
469 | enable_compat20(); | |
470 | break; | |
471 | } | |
472 | /* FALLTHROUGH */ | |
473 | default: | |
474 | mismatch = 1; | |
475 | break; | |
476 | } | |
477 | chop(server_version_string); | |
478 | debug("Local version string %.200s", server_version_string); | |
479 | ||
480 | if (mismatch) { | |
481 | s = "Protocol major versions differ.\n"; | |
482 | (void) atomicio(write, sock_out, s, strlen(s)); | |
483 | close(sock_in); | |
484 | close(sock_out); | |
485 | log("Protocol major versions differ for %s: %.200s vs. %.200s", | |
486 | get_remote_ipaddr(), | |
487 | server_version_string, client_version_string); | |
488 | fatal_cleanup(); | |
489 | } | |
490 | } | |
491 | ||
3c0ef626 | 492 | /* Destroy the host and server keys. They will no longer be needed. */ |
493 | void | |
494 | destroy_sensitive_data(void) | |
495 | { | |
496 | int i; | |
497 | ||
498 | if (sensitive_data.server_key) { | |
499 | key_free(sensitive_data.server_key); | |
500 | sensitive_data.server_key = NULL; | |
501 | } | |
1e608e42 | 502 | for (i = 0; i < options.num_host_key_files; i++) { |
3c0ef626 | 503 | if (sensitive_data.host_keys[i]) { |
504 | key_free(sensitive_data.host_keys[i]); | |
505 | sensitive_data.host_keys[i] = NULL; | |
506 | } | |
507 | } | |
508 | sensitive_data.ssh1_host_key = NULL; | |
509 | memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); | |
510 | } | |
511 | ||
2980ea68 | 512 | /* Demote private to public keys for network child */ |
513 | void | |
514 | demote_sensitive_data(void) | |
515 | { | |
516 | Key *tmp; | |
517 | int i; | |
518 | ||
519 | if (sensitive_data.server_key) { | |
520 | tmp = key_demote(sensitive_data.server_key); | |
521 | key_free(sensitive_data.server_key); | |
522 | sensitive_data.server_key = tmp; | |
523 | } | |
524 | ||
525 | for (i = 0; i < options.num_host_key_files; i++) { | |
526 | if (sensitive_data.host_keys[i]) { | |
527 | tmp = key_demote(sensitive_data.host_keys[i]); | |
528 | key_free(sensitive_data.host_keys[i]); | |
529 | sensitive_data.host_keys[i] = tmp; | |
530 | if (tmp->type == KEY_RSA1) | |
531 | sensitive_data.ssh1_host_key = tmp; | |
532 | } | |
533 | } | |
534 | ||
535 | /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ | |
536 | } | |
537 | ||
538 | static void | |
539 | privsep_preauth_child(void) | |
540 | { | |
541 | u_int32_t rand[256]; | |
ff2d7a98 | 542 | gid_t gidset[2]; |
2980ea68 | 543 | struct passwd *pw; |
ff2d7a98 | 544 | int i; |
2980ea68 | 545 | |
546 | /* Enable challenge-response authentication for privilege separation */ | |
547 | privsep_challenge_enable(); | |
548 | ||
549 | for (i = 0; i < 256; i++) | |
550 | rand[i] = arc4random(); | |
551 | RAND_seed(rand, sizeof(rand)); | |
552 | ||
553 | /* Demote the private keys to public keys. */ | |
554 | demote_sensitive_data(); | |
555 | ||
556 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
557 | fatal("Privilege separation user %s does not exist", | |
558 | SSH_PRIVSEP_USER); | |
559 | memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); | |
560 | endpwent(); | |
561 | ||
562 | /* Change our root directory*/ | |
563 | if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) | |
564 | fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, | |
565 | strerror(errno)); | |
566 | if (chdir("/") == -1) | |
567 | fatal("chdir(\"/\"): %s", strerror(errno)); | |
568 | ||
569 | /* Drop our privileges */ | |
570 | debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, | |
571 | (u_int)pw->pw_gid); | |
ff2d7a98 | 572 | #if 0 |
573 | /* XXX not ready, to heavy after chroot */ | |
2980ea68 | 574 | do_setusercontext(pw); |
ff2d7a98 | 575 | #else |
576 | gidset[0] = pw->pw_gid; | |
577 | if (setgid(pw->pw_gid) < 0) | |
578 | fatal("setgid failed for %u", pw->pw_gid ); | |
579 | if (setgroups(1, gidset) < 0) | |
580 | fatal("setgroups: %.100s", strerror(errno)); | |
581 | permanently_set_uid(pw); | |
582 | #endif | |
2980ea68 | 583 | } |
584 | ||
585 | static Authctxt* | |
586 | privsep_preauth(void) | |
587 | { | |
588 | Authctxt *authctxt = NULL; | |
589 | int status; | |
590 | pid_t pid; | |
591 | ||
592 | /* Set up unprivileged child process to deal with network data */ | |
593 | pmonitor = monitor_init(); | |
594 | /* Store a pointer to the kex for later rekeying */ | |
595 | pmonitor->m_pkex = &xxx_kex; | |
596 | ||
597 | pid = fork(); | |
598 | if (pid == -1) { | |
599 | fatal("fork of unprivileged child failed"); | |
600 | } else if (pid != 0) { | |
ff2d7a98 | 601 | debug2("Network child is on pid %ld", (long)pid); |
2980ea68 | 602 | |
603 | close(pmonitor->m_recvfd); | |
604 | authctxt = monitor_child_preauth(pmonitor); | |
605 | close(pmonitor->m_sendfd); | |
606 | ||
607 | /* Sync memory */ | |
608 | monitor_sync(pmonitor); | |
609 | ||
610 | /* Wait for the child's exit status */ | |
611 | while (waitpid(pid, &status, 0) < 0) | |
612 | if (errno != EINTR) | |
613 | break; | |
614 | return (authctxt); | |
615 | } else { | |
616 | /* child */ | |
617 | ||
618 | close(pmonitor->m_sendfd); | |
619 | ||
620 | /* Demote the child */ | |
621 | if (getuid() == 0 || geteuid() == 0) | |
622 | privsep_preauth_child(); | |
623 | setproctitle("%s", "[net]"); | |
624 | } | |
625 | return (NULL); | |
626 | } | |
627 | ||
628 | static void | |
629 | privsep_postauth(Authctxt *authctxt) | |
630 | { | |
631 | extern Authctxt *x_authctxt; | |
632 | ||
633 | /* XXX - Remote port forwarding */ | |
634 | x_authctxt = authctxt; | |
635 | ||
ff2d7a98 | 636 | #ifdef BROKEN_FD_PASSING |
637 | if (1) { | |
638 | #else | |
2980ea68 | 639 | if (authctxt->pw->pw_uid == 0 || options.use_login) { |
ff2d7a98 | 640 | #endif |
2980ea68 | 641 | /* File descriptor passing is broken or root login */ |
642 | monitor_apply_keystate(pmonitor); | |
643 | use_privsep = 0; | |
644 | return; | |
645 | } | |
646 | ||
647 | /* Authentication complete */ | |
648 | alarm(0); | |
649 | if (startup_pipe != -1) { | |
650 | close(startup_pipe); | |
651 | startup_pipe = -1; | |
652 | } | |
653 | ||
654 | /* New socket pair */ | |
655 | monitor_reinit(pmonitor); | |
656 | ||
657 | pmonitor->m_pid = fork(); | |
658 | if (pmonitor->m_pid == -1) | |
659 | fatal("fork of unprivileged child failed"); | |
660 | else if (pmonitor->m_pid != 0) { | |
ff2d7a98 | 661 | debug2("User child is on pid %ld", (long)pmonitor->m_pid); |
2980ea68 | 662 | close(pmonitor->m_recvfd); |
663 | monitor_child_postauth(pmonitor); | |
664 | ||
665 | /* NEVERREACHED */ | |
666 | exit(0); | |
667 | } | |
668 | ||
669 | close(pmonitor->m_sendfd); | |
670 | ||
671 | /* Demote the private keys to public keys. */ | |
672 | demote_sensitive_data(); | |
673 | ||
674 | /* Drop privileges */ | |
675 | do_setusercontext(authctxt->pw); | |
676 | ||
677 | /* It is safe now to apply the key state */ | |
678 | monitor_apply_keystate(pmonitor); | |
679 | } | |
680 | ||
3c0ef626 | 681 | static char * |
682 | list_hostkey_types(void) | |
683 | { | |
1e608e42 | 684 | Buffer b; |
685 | char *p; | |
3c0ef626 | 686 | int i; |
1e608e42 | 687 | |
688 | buffer_init(&b); | |
689 | for (i = 0; i < options.num_host_key_files; i++) { | |
3c0ef626 | 690 | Key *key = sensitive_data.host_keys[i]; |
691 | if (key == NULL) | |
692 | continue; | |
1e608e42 | 693 | switch (key->type) { |
3c0ef626 | 694 | case KEY_RSA: |
695 | case KEY_DSA: | |
1e608e42 | 696 | if (buffer_len(&b) > 0) |
697 | buffer_append(&b, ",", 1); | |
698 | p = key_ssh_name(key); | |
699 | buffer_append(&b, p, strlen(p)); | |
3c0ef626 | 700 | break; |
701 | } | |
702 | } | |
1e608e42 | 703 | buffer_append(&b, "\0", 1); |
704 | p = xstrdup(buffer_ptr(&b)); | |
705 | buffer_free(&b); | |
706 | debug("list_hostkey_types: %s", p); | |
707 | return p; | |
3c0ef626 | 708 | } |
709 | ||
2980ea68 | 710 | Key * |
3c0ef626 | 711 | get_hostkey_by_type(int type) |
712 | { | |
713 | int i; | |
ff2d7a98 | 714 | |
1e608e42 | 715 | for (i = 0; i < options.num_host_key_files; i++) { |
3c0ef626 | 716 | Key *key = sensitive_data.host_keys[i]; |
717 | if (key != NULL && key->type == type) | |
718 | return key; | |
719 | } | |
720 | return NULL; | |
721 | } | |
722 | ||
2980ea68 | 723 | Key * |
724 | get_hostkey_by_index(int ind) | |
725 | { | |
726 | if (ind < 0 || ind >= options.num_host_key_files) | |
727 | return (NULL); | |
728 | return (sensitive_data.host_keys[ind]); | |
729 | } | |
730 | ||
731 | int | |
732 | get_hostkey_index(Key *key) | |
733 | { | |
734 | int i; | |
ff2d7a98 | 735 | |
2980ea68 | 736 | for (i = 0; i < options.num_host_key_files; i++) { |
737 | if (key == sensitive_data.host_keys[i]) | |
738 | return (i); | |
739 | } | |
740 | return (-1); | |
741 | } | |
742 | ||
3c0ef626 | 743 | /* |
744 | * returns 1 if connection should be dropped, 0 otherwise. | |
745 | * dropping starts at connection #max_startups_begin with a probability | |
746 | * of (max_startups_rate/100). the probability increases linearly until | |
747 | * all connections are dropped for startups > max_startups | |
748 | */ | |
749 | static int | |
750 | drop_connection(int startups) | |
751 | { | |
752 | double p, r; | |
753 | ||
754 | if (startups < options.max_startups_begin) | |
755 | return 0; | |
756 | if (startups >= options.max_startups) | |
757 | return 1; | |
758 | if (options.max_startups_rate == 100) | |
759 | return 1; | |
760 | ||
761 | p = 100 - options.max_startups_rate; | |
762 | p *= startups - options.max_startups_begin; | |
763 | p /= (double) (options.max_startups - options.max_startups_begin); | |
764 | p += options.max_startups_rate; | |
765 | p /= 100.0; | |
766 | r = arc4random() / (double) UINT_MAX; | |
767 | ||
768 | debug("drop_connection: p %g, r %g", p, r); | |
769 | return (r < p) ? 1 : 0; | |
770 | } | |
771 | ||
1e608e42 | 772 | static void |
773 | usage(void) | |
774 | { | |
775 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
776 | fprintf(stderr, "Usage: %s [options]\n", __progname); | |
777 | fprintf(stderr, "Options:\n"); | |
778 | fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE); | |
779 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); | |
780 | fprintf(stderr, " -i Started from inetd\n"); | |
781 | fprintf(stderr, " -D Do not fork into daemon mode\n"); | |
782 | fprintf(stderr, " -t Only test configuration file and keys\n"); | |
783 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
784 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
785 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
786 | fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n"); | |
787 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
788 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
789 | _PATH_HOST_KEY_FILE); | |
790 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); | |
791 | fprintf(stderr, " -4 Use IPv4 only\n"); | |
792 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
793 | fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n"); | |
794 | exit(1); | |
795 | } | |
3c0ef626 | 796 | |
797 | /* | |
798 | * Main program for the daemon. | |
799 | */ | |
800 | int | |
801 | main(int ac, char **av) | |
802 | { | |
803 | extern char *optarg; | |
804 | extern int optind; | |
805 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; | |
806 | pid_t pid; | |
807 | socklen_t fromlen; | |
808 | fd_set *fdset; | |
809 | struct sockaddr_storage from; | |
810 | const char *remote_ip; | |
811 | int remote_port; | |
812 | FILE *f; | |
813 | struct linger linger; | |
814 | struct addrinfo *ai; | |
815 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
816 | int listen_sock, maxfd; | |
817 | int startup_p[2]; | |
818 | int startups = 0; | |
2980ea68 | 819 | Authctxt *authctxt; |
3c0ef626 | 820 | Key *key; |
821 | int ret, key_used = 0; | |
822 | ||
2980ea68 | 823 | #ifdef HAVE_SECUREWARE |
824 | (void)set_auth_parameters(ac, av); | |
825 | #endif | |
3c0ef626 | 826 | __progname = get_progname(av[0]); |
ae43c103 | 827 | init_pathnames(); |
828 | config_file_name = _PATH_SERVER_CONFIG_FILE; | |
3c0ef626 | 829 | init_rng(); |
830 | ||
831 | /* Save argv. */ | |
832 | saved_argc = ac; | |
833 | saved_argv = av; | |
834 | ||
835 | /* Initialize configuration options to their default values. */ | |
836 | initialize_server_options(&options); | |
837 | ||
838 | /* Parse command-line arguments. */ | |
1e608e42 | 839 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) { |
3c0ef626 | 840 | switch (opt) { |
841 | case '4': | |
842 | IPv4or6 = AF_INET; | |
843 | break; | |
844 | case '6': | |
845 | IPv4or6 = AF_INET6; | |
846 | break; | |
847 | case 'f': | |
848 | config_file_name = optarg; | |
849 | break; | |
850 | case 'd': | |
851 | if (0 == debug_flag) { | |
852 | debug_flag = 1; | |
853 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
854 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
855 | options.log_level++; | |
856 | } else { | |
857 | fprintf(stderr, "Too high debugging level.\n"); | |
858 | exit(1); | |
859 | } | |
860 | break; | |
861 | case 'D': | |
862 | no_daemon_flag = 1; | |
863 | break; | |
864 | case 'e': | |
865 | log_stderr = 1; | |
866 | break; | |
867 | case 'i': | |
868 | inetd_flag = 1; | |
869 | break; | |
870 | case 'Q': | |
871 | /* ignored */ | |
872 | break; | |
873 | case 'q': | |
874 | options.log_level = SYSLOG_LEVEL_QUIET; | |
875 | break; | |
876 | case 'b': | |
877 | options.server_key_bits = atoi(optarg); | |
878 | break; | |
879 | case 'p': | |
880 | options.ports_from_cmdline = 1; | |
881 | if (options.num_ports >= MAX_PORTS) { | |
882 | fprintf(stderr, "too many ports.\n"); | |
883 | exit(1); | |
884 | } | |
885 | options.ports[options.num_ports++] = a2port(optarg); | |
886 | if (options.ports[options.num_ports-1] == 0) { | |
887 | fprintf(stderr, "Bad port number.\n"); | |
888 | exit(1); | |
889 | } | |
890 | break; | |
891 | case 'g': | |
892 | if ((options.login_grace_time = convtime(optarg)) == -1) { | |
893 | fprintf(stderr, "Invalid login grace time.\n"); | |
894 | exit(1); | |
895 | } | |
896 | break; | |
897 | case 'k': | |
898 | if ((options.key_regeneration_time = convtime(optarg)) == -1) { | |
899 | fprintf(stderr, "Invalid key regeneration interval.\n"); | |
900 | exit(1); | |
901 | } | |
902 | break; | |
903 | case 'h': | |
904 | if (options.num_host_key_files >= MAX_HOSTKEYS) { | |
905 | fprintf(stderr, "too many host keys.\n"); | |
906 | exit(1); | |
907 | } | |
908 | options.host_key_files[options.num_host_key_files++] = optarg; | |
909 | break; | |
910 | case 'V': | |
911 | client_version_string = optarg; | |
912 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
913 | inetd_flag = 1; | |
914 | break; | |
915 | case 't': | |
916 | test_flag = 1; | |
917 | break; | |
918 | case 'u': | |
919 | utmp_len = atoi(optarg); | |
920 | break; | |
1e608e42 | 921 | case 'o': |
922 | if (process_server_config_line(&options, optarg, | |
923 | "command-line", 0) != 0) | |
924 | exit(1); | |
925 | break; | |
3c0ef626 | 926 | case '?': |
927 | default: | |
1e608e42 | 928 | usage(); |
929 | break; | |
3c0ef626 | 930 | } |
931 | } | |
932 | SSLeay_add_all_algorithms(); | |
933 | channel_set_af(IPv4or6); | |
934 | ||
935 | /* | |
936 | * Force logging to stderr until we have loaded the private host | |
937 | * key (unless started from inetd) | |
938 | */ | |
939 | log_init(__progname, | |
1e608e42 | 940 | options.log_level == SYSLOG_LEVEL_NOT_SET ? |
941 | SYSLOG_LEVEL_INFO : options.log_level, | |
942 | options.log_facility == SYSLOG_FACILITY_NOT_SET ? | |
943 | SYSLOG_FACILITY_AUTH : options.log_facility, | |
3c0ef626 | 944 | !inetd_flag); |
945 | ||
946 | #ifdef _CRAY | |
947 | /* Cray can define user privs drop all prives now! | |
948 | * Not needed on PRIV_SU systems! | |
949 | */ | |
950 | drop_cray_privs(); | |
951 | #endif | |
952 | ||
953 | seed_rng(); | |
954 | ||
955 | /* Read server configuration options from the configuration file. */ | |
956 | read_server_config(&options, config_file_name); | |
957 | ||
958 | /* Fill in default values for those options not explicitly set. */ | |
959 | fill_default_server_options(&options); | |
960 | ||
961 | /* Check that there are no remaining arguments. */ | |
962 | if (optind < ac) { | |
963 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
964 | exit(1); | |
965 | } | |
966 | ||
967 | debug("sshd version %.100s", SSH_VERSION); | |
968 | ||
969 | /* load private host keys */ | |
970 | sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*)); | |
1e608e42 | 971 | for (i = 0; i < options.num_host_key_files; i++) |
3c0ef626 | 972 | sensitive_data.host_keys[i] = NULL; |
973 | sensitive_data.server_key = NULL; | |
974 | sensitive_data.ssh1_host_key = NULL; | |
975 | sensitive_data.have_ssh1_key = 0; | |
976 | sensitive_data.have_ssh2_key = 0; | |
977 | ||
1e608e42 | 978 | for (i = 0; i < options.num_host_key_files; i++) { |
3c0ef626 | 979 | key = key_load_private(options.host_key_files[i], "", NULL); |
980 | sensitive_data.host_keys[i] = key; | |
981 | if (key == NULL) { | |
982 | error("Could not load host key: %s", | |
983 | options.host_key_files[i]); | |
984 | sensitive_data.host_keys[i] = NULL; | |
985 | continue; | |
986 | } | |
1e608e42 | 987 | switch (key->type) { |
3c0ef626 | 988 | case KEY_RSA1: |
989 | sensitive_data.ssh1_host_key = key; | |
990 | sensitive_data.have_ssh1_key = 1; | |
991 | break; | |
992 | case KEY_RSA: | |
993 | case KEY_DSA: | |
994 | sensitive_data.have_ssh2_key = 1; | |
995 | break; | |
996 | } | |
997 | debug("private host key: #%d type %d %s", i, key->type, | |
998 | key_type(key)); | |
999 | } | |
1000 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
1001 | log("Disabling protocol version 1. Could not load host key"); | |
1002 | options.protocol &= ~SSH_PROTO_1; | |
1003 | } | |
5598e598 | 1004 | #ifndef GSSAPI |
1005 | /* The GSSAPI key exchange can run without a host key */ | |
3c0ef626 | 1006 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { |
1007 | log("Disabling protocol version 2. Could not load host key"); | |
1008 | options.protocol &= ~SSH_PROTO_2; | |
1009 | } | |
5598e598 | 1010 | #endif |
3c0ef626 | 1011 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { |
1012 | log("sshd: no hostkeys available -- exiting."); | |
1013 | exit(1); | |
1014 | } | |
1015 | ||
1016 | /* Check certain values for sanity. */ | |
1017 | if (options.protocol & SSH_PROTO_1) { | |
1018 | if (options.server_key_bits < 512 || | |
1019 | options.server_key_bits > 32768) { | |
1020 | fprintf(stderr, "Bad server key size.\n"); | |
1021 | exit(1); | |
1022 | } | |
1023 | /* | |
1024 | * Check that server and host key lengths differ sufficiently. This | |
1025 | * is necessary to make double encryption work with rsaref. Oh, I | |
1026 | * hate software patents. I dont know if this can go? Niels | |
1027 | */ | |
1028 | if (options.server_key_bits > | |
ff2d7a98 | 1029 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - |
1030 | SSH_KEY_BITS_RESERVED && options.server_key_bits < | |
1031 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1032 | SSH_KEY_BITS_RESERVED) { | |
3c0ef626 | 1033 | options.server_key_bits = |
ff2d7a98 | 1034 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + |
1035 | SSH_KEY_BITS_RESERVED; | |
3c0ef626 | 1036 | debug("Forcing server key to %d bits to make it differ from host key.", |
1037 | options.server_key_bits); | |
1038 | } | |
1039 | } | |
1040 | ||
ff2d7a98 | 1041 | if (use_privsep) { |
1042 | struct passwd *pw; | |
1043 | struct stat st; | |
1044 | ||
1045 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
1046 | fatal("Privilege separation user %s does not exist", | |
1047 | SSH_PRIVSEP_USER); | |
1048 | if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || | |
1049 | (S_ISDIR(st.st_mode) == 0)) | |
1050 | fatal("Missing privilege separation directory: %s", | |
1051 | _PATH_PRIVSEP_CHROOT_DIR); | |
1052 | if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) | |
1053 | fatal("Bad owner or mode for %s", | |
1054 | _PATH_PRIVSEP_CHROOT_DIR); | |
1055 | } | |
1056 | ||
3c0ef626 | 1057 | /* Configuration looks good, so exit if in test mode. */ |
1058 | if (test_flag) | |
1059 | exit(0); | |
1060 | ||
0b582e46 | 1061 | #ifdef GSSAPI |
c7221eee | 1062 | ssh_gssapi_clean_env(); |
0b582e46 | 1063 | #endif /* GSSAPI */ |
0b582e46 | 1064 | |
2980ea68 | 1065 | /* |
1066 | * Clear out any supplemental groups we may have inherited. This | |
1067 | * prevents inadvertent creation of files with bad modes (in the | |
1068 | * portable version at least, it's certainly possible for PAM | |
1069 | * to create a file, and we can't control the code in every | |
1070 | * module which might be used). | |
1071 | */ | |
1072 | if (setgroups(0, NULL) < 0) | |
1073 | debug("setgroups() failed: %.200s", strerror(errno)); | |
3c0ef626 | 1074 | |
1075 | /* Initialize the log (it is reinitialized below in case we forked). */ | |
1076 | if (debug_flag && !inetd_flag) | |
1077 | log_stderr = 1; | |
1078 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1079 | ||
1080 | /* | |
1081 | * If not in debugging mode, and not started from inetd, disconnect | |
1082 | * from the controlling terminal, and fork. The original process | |
1083 | * exits. | |
1084 | */ | |
1085 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { | |
1086 | #ifdef TIOCNOTTY | |
1087 | int fd; | |
1088 | #endif /* TIOCNOTTY */ | |
1089 | if (daemon(0, 0) < 0) | |
1090 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1091 | ||
1092 | /* Disconnect from the controlling tty. */ | |
1093 | #ifdef TIOCNOTTY | |
1094 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); | |
1095 | if (fd >= 0) { | |
1096 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
1097 | close(fd); | |
1098 | } | |
1099 | #endif /* TIOCNOTTY */ | |
1100 | } | |
1101 | /* Reinitialize the log (because of the fork above). */ | |
1102 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1103 | ||
1104 | /* Initialize the random number generator. */ | |
1105 | arc4random_stir(); | |
1106 | ||
1107 | /* Chdir to the root directory so that the current disk can be | |
1108 | unmounted if desired. */ | |
1109 | chdir("/"); | |
1e608e42 | 1110 | |
3c0ef626 | 1111 | /* ignore SIGPIPE */ |
1112 | signal(SIGPIPE, SIG_IGN); | |
1113 | ||
1114 | /* Start listening for a socket, unless started from inetd. */ | |
1115 | if (inetd_flag) { | |
1116 | int s1; | |
1117 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ | |
1118 | dup(s1); | |
1119 | sock_in = dup(0); | |
1120 | sock_out = dup(1); | |
1121 | startup_pipe = -1; | |
1122 | /* | |
1123 | * We intentionally do not close the descriptors 0, 1, and 2 | |
1124 | * as our code for setting the descriptors won\'t work if | |
1125 | * ttyfd happens to be one of those. | |
1126 | */ | |
1127 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); | |
1128 | if (options.protocol & SSH_PROTO_1) | |
1129 | generate_ephemeral_server_key(); | |
1130 | } else { | |
1131 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { | |
1132 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
1133 | continue; | |
1134 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
1135 | fatal("Too many listen sockets. " | |
1136 | "Enlarge MAX_LISTEN_SOCKS"); | |
1137 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
1138 | ntop, sizeof(ntop), strport, sizeof(strport), | |
1139 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
1140 | error("getnameinfo failed"); | |
1141 | continue; | |
1142 | } | |
1143 | /* Create socket for listening. */ | |
1144 | listen_sock = socket(ai->ai_family, SOCK_STREAM, 0); | |
1145 | if (listen_sock < 0) { | |
1146 | /* kernel may not support ipv6 */ | |
1147 | verbose("socket: %.100s", strerror(errno)); | |
1148 | continue; | |
1149 | } | |
1150 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
1151 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
1152 | close(listen_sock); | |
1153 | continue; | |
1154 | } | |
1155 | /* | |
1156 | * Set socket options. We try to make the port | |
1157 | * reusable and have it close as fast as possible | |
1158 | * without waiting in unnecessary wait states on | |
1159 | * close. | |
1160 | */ | |
1161 | setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, | |
1e608e42 | 1162 | &on, sizeof(on)); |
3c0ef626 | 1163 | linger.l_onoff = 1; |
1164 | linger.l_linger = 5; | |
1165 | setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, | |
1e608e42 | 1166 | &linger, sizeof(linger)); |
3c0ef626 | 1167 | |
1168 | debug("Bind to port %s on %s.", strport, ntop); | |
1169 | ||
1170 | /* Bind the socket to the desired port. */ | |
1171 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { | |
1172 | if (!ai->ai_next) | |
1173 | error("Bind to port %s on %s failed: %.200s.", | |
1174 | strport, ntop, strerror(errno)); | |
1175 | close(listen_sock); | |
1176 | continue; | |
1177 | } | |
1178 | listen_socks[num_listen_socks] = listen_sock; | |
1179 | num_listen_socks++; | |
1180 | ||
1181 | /* Start listening on the port. */ | |
1182 | log("Server listening on %s port %s.", ntop, strport); | |
1183 | if (listen(listen_sock, 5) < 0) | |
1184 | fatal("listen: %.100s", strerror(errno)); | |
1185 | ||
1186 | } | |
1187 | freeaddrinfo(options.listen_addrs); | |
1188 | ||
1189 | if (!num_listen_socks) | |
1190 | fatal("Cannot bind any address."); | |
1191 | ||
1192 | if (options.protocol & SSH_PROTO_1) | |
1193 | generate_ephemeral_server_key(); | |
1194 | ||
1195 | /* | |
1196 | * Arrange to restart on SIGHUP. The handler needs | |
1197 | * listen_sock. | |
1198 | */ | |
1199 | signal(SIGHUP, sighup_handler); | |
1200 | ||
1201 | signal(SIGTERM, sigterm_handler); | |
1202 | signal(SIGQUIT, sigterm_handler); | |
1203 | ||
1204 | /* Arrange SIGCHLD to be caught. */ | |
1205 | signal(SIGCHLD, main_sigchld_handler); | |
1206 | ||
1207 | /* Write out the pid file after the sigterm handler is setup */ | |
1208 | if (!debug_flag) { | |
1209 | /* | |
1210 | * Record our pid in /var/run/sshd.pid to make it | |
1211 | * easier to kill the correct sshd. We don't want to | |
1212 | * do this before the bind above because the bind will | |
1213 | * fail if there already is a daemon, and this will | |
1214 | * overwrite any old pid in the file. | |
1215 | */ | |
1216 | f = fopen(options.pid_file, "wb"); | |
1217 | if (f) { | |
ff2d7a98 | 1218 | fprintf(f, "%ld\n", (long) getpid()); |
3c0ef626 | 1219 | fclose(f); |
1220 | } | |
1221 | } | |
1222 | ||
1223 | /* setup fd set for listen */ | |
1224 | fdset = NULL; | |
1225 | maxfd = 0; | |
1226 | for (i = 0; i < num_listen_socks; i++) | |
1227 | if (listen_socks[i] > maxfd) | |
1228 | maxfd = listen_socks[i]; | |
1229 | /* pipes connected to unauthenticated childs */ | |
1230 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
1231 | for (i = 0; i < options.max_startups; i++) | |
1232 | startup_pipes[i] = -1; | |
1233 | ||
1234 | /* | |
1235 | * Stay listening for connections until the system crashes or | |
1236 | * the daemon is killed with a signal. | |
1237 | */ | |
1238 | for (;;) { | |
1239 | if (received_sighup) | |
1240 | sighup_restart(); | |
1241 | if (fdset != NULL) | |
1242 | xfree(fdset); | |
1243 | fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); | |
1244 | fdset = (fd_set *)xmalloc(fdsetsz); | |
1245 | memset(fdset, 0, fdsetsz); | |
1246 | ||
1247 | for (i = 0; i < num_listen_socks; i++) | |
1248 | FD_SET(listen_socks[i], fdset); | |
1249 | for (i = 0; i < options.max_startups; i++) | |
1250 | if (startup_pipes[i] != -1) | |
1251 | FD_SET(startup_pipes[i], fdset); | |
1252 | ||
1253 | /* Wait in select until there is a connection. */ | |
1254 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); | |
1255 | if (ret < 0 && errno != EINTR) | |
1256 | error("select: %.100s", strerror(errno)); | |
1257 | if (received_sigterm) { | |
1258 | log("Received signal %d; terminating.", | |
1e608e42 | 1259 | (int) received_sigterm); |
3c0ef626 | 1260 | close_listen_socks(); |
1261 | unlink(options.pid_file); | |
1262 | exit(255); | |
1263 | } | |
1264 | if (key_used && key_do_regen) { | |
1265 | generate_ephemeral_server_key(); | |
1266 | key_used = 0; | |
1267 | key_do_regen = 0; | |
1268 | } | |
1269 | if (ret < 0) | |
1270 | continue; | |
1271 | ||
1272 | for (i = 0; i < options.max_startups; i++) | |
1273 | if (startup_pipes[i] != -1 && | |
1274 | FD_ISSET(startup_pipes[i], fdset)) { | |
1275 | /* | |
1276 | * the read end of the pipe is ready | |
1277 | * if the child has closed the pipe | |
1278 | * after successful authentication | |
1279 | * or if the child has died | |
1280 | */ | |
1281 | close(startup_pipes[i]); | |
1282 | startup_pipes[i] = -1; | |
1283 | startups--; | |
1284 | } | |
1285 | for (i = 0; i < num_listen_socks; i++) { | |
1286 | if (!FD_ISSET(listen_socks[i], fdset)) | |
1287 | continue; | |
1288 | fromlen = sizeof(from); | |
1289 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
1290 | &fromlen); | |
1291 | if (newsock < 0) { | |
1292 | if (errno != EINTR && errno != EWOULDBLOCK) | |
1293 | error("accept: %.100s", strerror(errno)); | |
1294 | continue; | |
1295 | } | |
1296 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
1297 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
1e608e42 | 1298 | close(newsock); |
3c0ef626 | 1299 | continue; |
1300 | } | |
1301 | if (drop_connection(startups) == 1) { | |
1302 | debug("drop connection #%d", startups); | |
1303 | close(newsock); | |
1304 | continue; | |
1305 | } | |
1306 | if (pipe(startup_p) == -1) { | |
1307 | close(newsock); | |
1308 | continue; | |
1309 | } | |
1310 | ||
1311 | for (j = 0; j < options.max_startups; j++) | |
1312 | if (startup_pipes[j] == -1) { | |
1313 | startup_pipes[j] = startup_p[0]; | |
1314 | if (maxfd < startup_p[0]) | |
1315 | maxfd = startup_p[0]; | |
1316 | startups++; | |
1317 | break; | |
1318 | } | |
1319 | ||
1320 | /* | |
1321 | * Got connection. Fork a child to handle it, unless | |
1322 | * we are in debugging mode. | |
1323 | */ | |
1324 | if (debug_flag) { | |
1325 | /* | |
1326 | * In debugging mode. Close the listening | |
1327 | * socket, and start processing the | |
1328 | * connection without forking. | |
1329 | */ | |
1330 | debug("Server will not fork when running in debugging mode."); | |
1331 | close_listen_socks(); | |
1332 | sock_in = newsock; | |
1333 | sock_out = newsock; | |
1334 | startup_pipe = -1; | |
1335 | pid = getpid(); | |
1336 | break; | |
1337 | } else { | |
1338 | /* | |
1339 | * Normal production daemon. Fork, and have | |
1340 | * the child process the connection. The | |
1341 | * parent continues listening. | |
1342 | */ | |
1343 | if ((pid = fork()) == 0) { | |
1344 | /* | |
1345 | * Child. Close the listening and max_startup | |
1346 | * sockets. Start using the accepted socket. | |
1347 | * Reinitialize logging (since our pid has | |
1348 | * changed). We break out of the loop to handle | |
1349 | * the connection. | |
1350 | */ | |
1351 | startup_pipe = startup_p[1]; | |
1e608e42 | 1352 | close_startup_pipes(); |
3c0ef626 | 1353 | close_listen_socks(); |
1354 | sock_in = newsock; | |
1355 | sock_out = newsock; | |
1356 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1357 | break; | |
1358 | } | |
1359 | } | |
1360 | ||
1361 | /* Parent. Stay in the loop. */ | |
1362 | if (pid < 0) | |
1363 | error("fork: %.100s", strerror(errno)); | |
1364 | else | |
ff2d7a98 | 1365 | debug("Forked child %ld.", (long)pid); |
3c0ef626 | 1366 | |
1367 | close(startup_p[1]); | |
1368 | ||
1369 | /* Mark that the key has been used (it was "given" to the child). */ | |
1370 | if ((options.protocol & SSH_PROTO_1) && | |
1371 | key_used == 0) { | |
1372 | /* Schedule server key regeneration alarm. */ | |
1373 | signal(SIGALRM, key_regeneration_alarm); | |
1374 | alarm(options.key_regeneration_time); | |
1375 | key_used = 1; | |
1376 | } | |
1377 | ||
1378 | arc4random_stir(); | |
1379 | ||
1380 | /* Close the new socket (the child is now taking care of it). */ | |
1381 | close(newsock); | |
1382 | } | |
1383 | /* child process check (or debug mode) */ | |
1384 | if (num_listen_socks < 0) | |
1385 | break; | |
1386 | } | |
1387 | } | |
1388 | ||
1389 | /* This is the child processing a new connection. */ | |
1390 | ||
2980ea68 | 1391 | /* |
1392 | * Create a new session and process group since the 4.4BSD | |
1393 | * setlogin() affects the entire process group. We don't | |
1394 | * want the child to be able to affect the parent. | |
1395 | */ | |
1396 | #if 0 | |
1397 | /* XXX: this breaks Solaris */ | |
ff2d7a98 | 1398 | if (!debug_flag && !inetd_flag && setsid() < 0) |
2980ea68 | 1399 | error("setsid: %.100s", strerror(errno)); |
1400 | #endif | |
1401 | ||
3c0ef626 | 1402 | /* |
1403 | * Disable the key regeneration alarm. We will not regenerate the | |
1404 | * key since we are no longer in a position to give it to anyone. We | |
1405 | * will not restart on SIGHUP since it no longer makes sense. | |
1406 | */ | |
1407 | alarm(0); | |
1408 | signal(SIGALRM, SIG_DFL); | |
1409 | signal(SIGHUP, SIG_DFL); | |
1410 | signal(SIGTERM, SIG_DFL); | |
1411 | signal(SIGQUIT, SIG_DFL); | |
1412 | signal(SIGCHLD, SIG_DFL); | |
1413 | signal(SIGINT, SIG_DFL); | |
1414 | ||
1415 | /* | |
1416 | * Set socket options for the connection. We want the socket to | |
1417 | * close as fast as possible without waiting for anything. If the | |
1418 | * connection is not a socket, these will do nothing. | |
1419 | */ | |
1420 | /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
1421 | linger.l_onoff = 1; | |
1422 | linger.l_linger = 5; | |
1e608e42 | 1423 | setsockopt(sock_in, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger)); |
3c0ef626 | 1424 | |
1425 | /* Set keepalives if requested. */ | |
1426 | if (options.keepalives && | |
1e608e42 | 1427 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, |
3c0ef626 | 1428 | sizeof(on)) < 0) |
1429 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1430 | ||
1431 | /* | |
1432 | * Register our connection. This turns encryption off because we do | |
1433 | * not have a key. | |
1434 | */ | |
1435 | packet_set_connection(sock_in, sock_out); | |
1436 | ||
1437 | remote_port = get_remote_port(); | |
1438 | remote_ip = get_remote_ipaddr(); | |
1439 | ||
1440 | #ifdef LIBWRAP | |
1441 | /* Check whether logins are denied from this host. */ | |
1442 | { | |
1443 | struct request_info req; | |
1444 | ||
1445 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); | |
1446 | fromhost(&req); | |
1447 | ||
1448 | if (!hosts_access(&req)) { | |
1449 | debug("Connection refused by tcp wrapper"); | |
1450 | refuse(&req); | |
1451 | /* NOTREACHED */ | |
1452 | fatal("libwrap refuse returns"); | |
1453 | } | |
1454 | } | |
1455 | #endif /* LIBWRAP */ | |
1456 | ||
1457 | /* Log the connection. */ | |
1458 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
1459 | ||
1460 | /* | |
1461 | * We don\'t want to listen forever unless the other side | |
1462 | * successfully authenticates itself. So we set up an alarm which is | |
1463 | * cleared after successful authentication. A limit of zero | |
1464 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1465 | * mode; it is just annoying to have the server exit just when you | |
1466 | * are about to discover the bug. | |
1467 | */ | |
1468 | signal(SIGALRM, grace_alarm_handler); | |
1469 | if (!debug_flag) | |
1470 | alarm(options.login_grace_time); | |
1471 | ||
1472 | sshd_exchange_identification(sock_in, sock_out); | |
1473 | /* | |
1474 | * Check that the connection comes from a privileged port. | |
ff2d7a98 | 1475 | * Rhosts-Authentication only makes sense from privileged |
3c0ef626 | 1476 | * programs. Of course, if the intruder has root access on his local |
1477 | * machine, he can connect from any port. So do not use these | |
1478 | * authentication methods from machines that you do not trust. | |
1479 | */ | |
1e608e42 | 1480 | if (options.rhosts_authentication && |
1481 | (remote_port >= IPPORT_RESERVED || | |
1482 | remote_port < IPPORT_RESERVED / 2)) { | |
3c0ef626 | 1483 | debug("Rhosts Authentication disabled, " |
1484 | "originating port %d not trusted.", remote_port); | |
1485 | options.rhosts_authentication = 0; | |
1486 | } | |
1487 | #if defined(KRB4) && !defined(KRB5) | |
1488 | if (!packet_connection_is_ipv4() && | |
1489 | options.kerberos_authentication) { | |
1490 | debug("Kerberos Authentication disabled, only available for IPv4."); | |
1491 | options.kerberos_authentication = 0; | |
1492 | } | |
1493 | #endif /* KRB4 && !KRB5 */ | |
1494 | #ifdef AFS | |
1495 | /* If machine has AFS, set process authentication group. */ | |
1496 | if (k_hasafs()) { | |
1497 | k_setpag(); | |
1498 | k_unlog(); | |
1499 | } | |
1500 | #endif /* AFS */ | |
1501 | ||
1502 | packet_set_nonblocking(); | |
1503 | ||
2980ea68 | 1504 | if (use_privsep) |
1505 | if ((authctxt = privsep_preauth()) != NULL) | |
1506 | goto authenticated; | |
1507 | ||
3c0ef626 | 1508 | /* perform the key exchange */ |
1509 | /* authenticate user and start session */ | |
1510 | if (compat20) { | |
1511 | do_ssh2_kex(); | |
2980ea68 | 1512 | authctxt = do_authentication2(); |
3c0ef626 | 1513 | } else { |
1514 | do_ssh1_kex(); | |
2980ea68 | 1515 | authctxt = do_authentication(); |
1516 | } | |
1517 | /* | |
1518 | * If we use privilege separation, the unprivileged child transfers | |
1519 | * the current keystate and exits | |
1520 | */ | |
1521 | if (use_privsep) { | |
1522 | mm_send_keystate(pmonitor); | |
1523 | exit(0); | |
3c0ef626 | 1524 | } |
2980ea68 | 1525 | |
1526 | authenticated: | |
1527 | /* | |
1528 | * In privilege separation, we fork another child and prepare | |
1529 | * file descriptor passing. | |
1530 | */ | |
1531 | if (use_privsep) { | |
1532 | privsep_postauth(authctxt); | |
1533 | /* the monitor process [priv] will not return */ | |
1534 | if (!compat20) | |
1535 | destroy_sensitive_data(); | |
1536 | } | |
1537 | ||
1538 | /* Perform session preparation. */ | |
1539 | do_authenticated(authctxt); | |
1540 | ||
3c0ef626 | 1541 | /* The connection has been terminated. */ |
1542 | verbose("Closing connection to %.100s", remote_ip); | |
1543 | ||
1544 | #ifdef USE_PAM | |
1545 | finish_pam(); | |
1546 | #endif /* USE_PAM */ | |
1547 | ||
1548 | packet_close(); | |
2980ea68 | 1549 | |
1550 | if (use_privsep) | |
1551 | mm_terminate(); | |
1552 | ||
3c0ef626 | 1553 | exit(0); |
1554 | } | |
1555 | ||
2980ea68 | 1556 | /* |
1557 | * Decrypt session_key_int using our private server key and private host key | |
1558 | * (key with larger modulus first). | |
1559 | */ | |
1560 | int | |
1561 | ssh1_session_key(BIGNUM *session_key_int) | |
1562 | { | |
1563 | int rsafail = 0; | |
1564 | ||
1565 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { | |
1566 | /* Server key has bigger modulus. */ | |
1567 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < | |
1568 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1569 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1570 | get_remote_ipaddr(), | |
1571 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1572 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1573 | SSH_KEY_BITS_RESERVED); | |
1574 | } | |
1575 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1576 | sensitive_data.server_key->rsa) <= 0) | |
1577 | rsafail++; | |
1578 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1579 | sensitive_data.ssh1_host_key->rsa) <= 0) | |
1580 | rsafail++; | |
1581 | } else { | |
1582 | /* Host key has bigger modulus (or they are equal). */ | |
1583 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < | |
1584 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1585 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1586 | get_remote_ipaddr(), | |
1587 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1588 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1589 | SSH_KEY_BITS_RESERVED); | |
1590 | } | |
1591 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1592 | sensitive_data.ssh1_host_key->rsa) < 0) | |
1593 | rsafail++; | |
1594 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1595 | sensitive_data.server_key->rsa) < 0) | |
1596 | rsafail++; | |
1597 | } | |
1598 | return (rsafail); | |
1599 | } | |
3c0ef626 | 1600 | /* |
1601 | * SSH1 key exchange | |
1602 | */ | |
1603 | static void | |
1604 | do_ssh1_kex(void) | |
1605 | { | |
1606 | int i, len; | |
3c0ef626 | 1607 | int rsafail = 0; |
1608 | BIGNUM *session_key_int; | |
1609 | u_char session_key[SSH_SESSION_KEY_LENGTH]; | |
1610 | u_char cookie[8]; | |
1611 | u_int cipher_type, auth_mask, protocol_flags; | |
1612 | u_int32_t rand = 0; | |
1613 | ||
1614 | /* | |
1615 | * Generate check bytes that the client must send back in the user | |
1616 | * packet in order for it to be accepted; this is used to defy ip | |
1617 | * spoofing attacks. Note that this only works against somebody | |
1618 | * doing IP spoofing from a remote machine; any machine on the local | |
1619 | * network can still see outgoing packets and catch the random | |
1620 | * cookie. This only affects rhosts authentication, and this is one | |
1621 | * of the reasons why it is inherently insecure. | |
1622 | */ | |
1623 | for (i = 0; i < 8; i++) { | |
1624 | if (i % 4 == 0) | |
1625 | rand = arc4random(); | |
1626 | cookie[i] = rand & 0xff; | |
1627 | rand >>= 8; | |
1628 | } | |
1629 | ||
1630 | /* | |
1631 | * Send our public key. We include in the packet 64 bits of random | |
1632 | * data that must be matched in the reply in order to prevent IP | |
1633 | * spoofing. | |
1634 | */ | |
1635 | packet_start(SSH_SMSG_PUBLIC_KEY); | |
1636 | for (i = 0; i < 8; i++) | |
1637 | packet_put_char(cookie[i]); | |
1638 | ||
1639 | /* Store our public server RSA key. */ | |
1640 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); | |
1641 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1642 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
1643 | ||
1644 | /* Store our public host RSA key. */ | |
1645 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
1646 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1647 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
1648 | ||
1649 | /* Put protocol flags. */ | |
1650 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1651 | ||
1652 | /* Declare which ciphers we support. */ | |
1653 | packet_put_int(cipher_mask_ssh1(0)); | |
1654 | ||
1655 | /* Declare supported authentication types. */ | |
1656 | auth_mask = 0; | |
1657 | if (options.rhosts_authentication) | |
1658 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
1659 | if (options.rhosts_rsa_authentication) | |
1660 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1661 | if (options.rsa_authentication) | |
1662 | auth_mask |= 1 << SSH_AUTH_RSA; | |
1663 | #if defined(KRB4) || defined(KRB5) | |
1664 | if (options.kerberos_authentication) | |
1665 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
1666 | #endif | |
1667 | #if defined(AFS) || defined(KRB5) | |
1668 | if (options.kerberos_tgt_passing) | |
1669 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
1670 | #endif | |
1671 | #ifdef AFS | |
1672 | if (options.afs_token_passing) | |
1673 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
1674 | #endif | |
0b582e46 | 1675 | #ifdef GSSAPI |
ff2d7a98 | 1676 | if (options.gss_authentication) |
1677 | auth_mask |= 1 << SSH_AUTH_GSSAPI; | |
0b582e46 | 1678 | #endif |
ff2d7a98 | 1679 | if (options.challenge_response_authentication == 1) |
1680 | auth_mask |= 1 << SSH_AUTH_TIS; | |
3c0ef626 | 1681 | if (options.password_authentication) |
1682 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1683 | packet_put_int(auth_mask); | |
1684 | ||
1685 | /* Send the packet and wait for it to be sent. */ | |
1686 | packet_send(); | |
1687 | packet_write_wait(); | |
1688 | ||
1689 | debug("Sent %d bit server key and %d bit host key.", | |
1690 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1691 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
1692 | ||
1693 | /* Read clients reply (cipher type and session key). */ | |
1e608e42 | 1694 | packet_read_expect(SSH_CMSG_SESSION_KEY); |
3c0ef626 | 1695 | |
1696 | /* Get cipher type and check whether we accept this. */ | |
1697 | cipher_type = packet_get_char(); | |
1698 | ||
1699 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) | |
1700 | packet_disconnect("Warning: client selects unsupported cipher."); | |
1701 | ||
1702 | /* Get check bytes from the packet. These must match those we | |
1703 | sent earlier with the public key packet. */ | |
1704 | for (i = 0; i < 8; i++) | |
1705 | if (cookie[i] != packet_get_char()) | |
1706 | packet_disconnect("IP Spoofing check bytes do not match."); | |
1707 | ||
1708 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1709 | ||
1710 | /* Get the encrypted integer. */ | |
1e608e42 | 1711 | if ((session_key_int = BN_new()) == NULL) |
1712 | fatal("do_ssh1_kex: BN_new failed"); | |
1713 | packet_get_bignum(session_key_int); | |
3c0ef626 | 1714 | |
1715 | protocol_flags = packet_get_int(); | |
1716 | packet_set_protocol_flags(protocol_flags); | |
1e608e42 | 1717 | packet_check_eom(); |
3c0ef626 | 1718 | |
2980ea68 | 1719 | /* Decrypt session_key_int using host/server keys */ |
1720 | rsafail = PRIVSEP(ssh1_session_key(session_key_int)); | |
1721 | ||
3c0ef626 | 1722 | /* |
1723 | * Extract session key from the decrypted integer. The key is in the | |
1724 | * least significant 256 bits of the integer; the first byte of the | |
1725 | * key is in the highest bits. | |
1726 | */ | |
1727 | if (!rsafail) { | |
1728 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
1729 | len = BN_num_bytes(session_key_int); | |
1730 | if (len < 0 || len > sizeof(session_key)) { | |
1731 | error("do_connection: bad session key len from %s: " | |
1732 | "session_key_int %d > sizeof(session_key) %lu", | |
1733 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); | |
1734 | rsafail++; | |
1735 | } else { | |
1736 | memset(session_key, 0, sizeof(session_key)); | |
1737 | BN_bn2bin(session_key_int, | |
1738 | session_key + sizeof(session_key) - len); | |
1739 | ||
1740 | compute_session_id(session_id, cookie, | |
1741 | sensitive_data.ssh1_host_key->rsa->n, | |
1742 | sensitive_data.server_key->rsa->n); | |
1743 | /* | |
1744 | * Xor the first 16 bytes of the session key with the | |
1745 | * session id. | |
1746 | */ | |
1747 | for (i = 0; i < 16; i++) | |
1748 | session_key[i] ^= session_id[i]; | |
1749 | } | |
1750 | } | |
1751 | if (rsafail) { | |
1752 | int bytes = BN_num_bytes(session_key_int); | |
1e608e42 | 1753 | u_char *buf = xmalloc(bytes); |
3c0ef626 | 1754 | MD5_CTX md; |
1755 | ||
1756 | log("do_connection: generating a fake encryption key"); | |
1757 | BN_bn2bin(session_key_int, buf); | |
1758 | MD5_Init(&md); | |
1759 | MD5_Update(&md, buf, bytes); | |
1760 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1761 | MD5_Final(session_key, &md); | |
1762 | MD5_Init(&md); | |
1763 | MD5_Update(&md, session_key, 16); | |
1764 | MD5_Update(&md, buf, bytes); | |
1765 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1766 | MD5_Final(session_key + 16, &md); | |
1767 | memset(buf, 0, bytes); | |
1768 | xfree(buf); | |
1769 | for (i = 0; i < 16; i++) | |
1770 | session_id[i] = session_key[i] ^ session_key[i + 16]; | |
1771 | } | |
0b582e46 | 1772 | |
0b582e46 | 1773 | #ifdef GSSAPI |
1774 | /* | |
1775 | * Before we destroy the host and server keys, hash them so we can | |
1776 | * send the hash over to the client via a secure channel so that it | |
1777 | * can verify them. | |
1778 | */ | |
1779 | { | |
1780 | MD5_CTX md5context; | |
1781 | Buffer buf; | |
1782 | unsigned char *data; | |
1783 | unsigned int data_len; | |
ff2d7a98 | 1784 | extern unsigned char ssh1_key_digest[16]; /* in gss-genr.c */ |
0b582e46 | 1785 | |
1786 | ||
1787 | debug("Calculating MD5 hash of server and host keys..."); | |
1788 | ||
1789 | /* Write all the keys to a temporary buffer */ | |
1790 | buffer_init(&buf); | |
1791 | ||
1792 | /* Server key */ | |
1793 | buffer_put_bignum(&buf, sensitive_data.server_key->rsa->e); | |
1794 | buffer_put_bignum(&buf, sensitive_data.server_key->rsa->n); | |
1795 | ||
1796 | /* Host key */ | |
1797 | buffer_put_bignum(&buf, sensitive_data.ssh1_host_key->rsa->e); | |
1798 | buffer_put_bignum(&buf, sensitive_data.ssh1_host_key->rsa->n); | |
1799 | ||
1800 | /* Get the resulting data */ | |
1801 | data = (unsigned char *) buffer_ptr(&buf); | |
1802 | data_len = buffer_len(&buf); | |
1803 | ||
1804 | /* And hash it */ | |
1805 | MD5_Init(&md5context); | |
1806 | MD5_Update(&md5context, data, data_len); | |
c3f0c567 | 1807 | MD5_Final(ssh1_key_digest, &md5context); |
0b582e46 | 1808 | |
1809 | /* Clean up */ | |
1810 | buffer_clear(&buf); | |
1811 | buffer_free(&buf); | |
1812 | } | |
1813 | #endif /* GSSAPI */ | |
0b582e46 | 1814 | |
2980ea68 | 1815 | /* Destroy the private and public keys. No longer. */ |
3c0ef626 | 1816 | destroy_sensitive_data(); |
1817 | ||
2980ea68 | 1818 | if (use_privsep) |
1819 | mm_ssh1_session_id(session_id); | |
1820 | ||
3c0ef626 | 1821 | /* Destroy the decrypted integer. It is no longer needed. */ |
1822 | BN_clear_free(session_key_int); | |
1823 | ||
1824 | /* Set the session key. From this on all communications will be encrypted. */ | |
1825 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1826 | ||
1827 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1828 | memset(session_key, 0, sizeof(session_key)); | |
1829 | ||
1830 | debug("Received session key; encryption turned on."); | |
1831 | ||
ff2d7a98 | 1832 | /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ |
3c0ef626 | 1833 | packet_start(SSH_SMSG_SUCCESS); |
1834 | packet_send(); | |
1835 | packet_write_wait(); | |
1836 | } | |
1837 | ||
1838 | /* | |
1839 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1840 | */ | |
1841 | static void | |
1842 | do_ssh2_kex(void) | |
1843 | { | |
1844 | Kex *kex; | |
1845 | ||
1846 | if (options.ciphers != NULL) { | |
1847 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
1848 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; | |
1849 | } | |
1850 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
1851 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); | |
1852 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
1853 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); | |
1854 | ||
1855 | if (options.macs != NULL) { | |
1856 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
1857 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
1858 | } | |
ff2d7a98 | 1859 | if (!options.compression) { |
1860 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
1861 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
1862 | } | |
3c0ef626 | 1863 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
1864 | ||
5598e598 | 1865 | #ifdef GSSAPI |
1866 | { | |
1867 | char *orig; | |
1868 | char *gss = NULL; | |
1869 | char *newstr = NULL; | |
1870 | orig = myproposal[PROPOSAL_KEX_ALGS]; | |
1871 | ||
1872 | /* If we don't have a host key, then all of the algorithms | |
1873 | * currently in myproposal are useless */ | |
1874 | if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])==0) | |
1875 | orig= NULL; | |
1876 | ||
1877 | if (options.gss_keyex) | |
1878 | gss = ssh_gssapi_mechanisms(1,NULL); | |
1879 | else | |
1880 | gss = NULL; | |
1881 | ||
1882 | if (gss && orig) { | |
1883 | int len = strlen(orig) + strlen(gss) +2; | |
1884 | newstr=xmalloc(len); | |
1885 | snprintf(newstr,len,"%s,%s",gss,orig); | |
1886 | } else if (gss) { | |
1887 | newstr=gss; | |
1888 | } else if (orig) { | |
1889 | newstr=orig; | |
1890 | } | |
1891 | /* If we've got GSSAPI mechanisms, then we've also got the 'null' | |
1892 | host key algorithm, but we're not allowed to advertise it, unless | |
1893 | its the only host key algorithm we're supporting */ | |
1894 | if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0) { | |
1895 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]="null"; | |
1896 | } | |
1897 | if (newstr) | |
1898 | myproposal[PROPOSAL_KEX_ALGS]=newstr; | |
1899 | else | |
1900 | fatal("No supported key exchange algorithms"); | |
1901 | } | |
1902 | #endif | |
1903 | ||
3c0ef626 | 1904 | /* start key exchange */ |
1905 | kex = kex_setup(myproposal); | |
1906 | kex->server = 1; | |
1907 | kex->client_version_string=client_version_string; | |
1908 | kex->server_version_string=server_version_string; | |
1909 | kex->load_host_key=&get_hostkey_by_type; | |
2980ea68 | 1910 | kex->host_key_index=&get_hostkey_index; |
3c0ef626 | 1911 | |
1912 | xxx_kex = kex; | |
1913 | ||
1914 | dispatch_run(DISPATCH_BLOCK, &kex->done, kex); | |
1915 | ||
1916 | session_id2 = kex->session_id; | |
1917 | session_id2_len = kex->session_id_len; | |
1918 | ||
1919 | #ifdef DEBUG_KEXDH | |
1920 | /* send 1st encrypted/maced/compressed message */ | |
1921 | packet_start(SSH2_MSG_IGNORE); | |
1922 | packet_put_cstring("markus"); | |
1923 | packet_send(); | |
1924 | packet_write_wait(); | |
1925 | #endif | |
1926 | debug("KEX done"); | |
1927 | } |