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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" | |
416fd2a8 | 45 | RCSID("$OpenBSD: sshd.c,v 1.286 2004/02/23 12:02:33 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 | |
416fd2a8 | 113 | extern char **environ; |
3c0ef626 | 114 | |
115 | /* Server configuration options. */ | |
116 | ServerOptions options; | |
117 | ||
118 | /* Name of the server configuration file. */ | |
ae43c103 | 119 | char *config_file_name; |
3c0ef626 | 120 | |
121 | /* | |
122 | * Flag indicating whether IPv4 or IPv6. This can be set on the command line. | |
123 | * Default value is AF_UNSPEC means both IPv4 and IPv6. | |
124 | */ | |
3c0ef626 | 125 | int IPv4or6 = AF_UNSPEC; |
3c0ef626 | 126 | |
127 | /* | |
128 | * Debug mode flag. This can be set on the command line. If debug | |
129 | * mode is enabled, extra debugging output will be sent to the system | |
130 | * log, the daemon will not go to background, and will exit after processing | |
131 | * the first connection. | |
132 | */ | |
133 | int debug_flag = 0; | |
134 | ||
135 | /* Flag indicating that the daemon should only test the configuration and keys. */ | |
136 | int test_flag = 0; | |
137 | ||
138 | /* Flag indicating that the daemon is being started from inetd. */ | |
139 | int inetd_flag = 0; | |
140 | ||
141 | /* Flag indicating that sshd should not detach and become a daemon. */ | |
142 | int no_daemon_flag = 0; | |
143 | ||
144 | /* debug goes to stderr unless inetd_flag is set */ | |
145 | int log_stderr = 0; | |
146 | ||
147 | /* Saved arguments to main(). */ | |
148 | char **saved_argv; | |
149 | int saved_argc; | |
150 | ||
151 | /* | |
152 | * The sockets that the server is listening; this is used in the SIGHUP | |
153 | * signal handler. | |
154 | */ | |
155 | #define MAX_LISTEN_SOCKS 16 | |
156 | int listen_socks[MAX_LISTEN_SOCKS]; | |
157 | int num_listen_socks = 0; | |
158 | ||
159 | /* | |
160 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
161 | * sshd will skip the version-number exchange | |
162 | */ | |
163 | char *client_version_string = NULL; | |
164 | char *server_version_string = NULL; | |
165 | ||
166 | /* for rekeying XXX fixme */ | |
167 | Kex *xxx_kex; | |
168 | ||
169 | /* | |
170 | * Any really sensitive data in the application is contained in this | |
171 | * structure. The idea is that this structure could be locked into memory so | |
172 | * that the pages do not get written into swap. However, there are some | |
173 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
174 | * have access to the internals of them, and locking just the structure is | |
175 | * not very useful. Currently, memory locking is not implemented. | |
176 | */ | |
177 | struct { | |
178 | Key *server_key; /* ephemeral server key */ | |
179 | Key *ssh1_host_key; /* ssh1 host key */ | |
180 | Key **host_keys; /* all private host keys */ | |
181 | int have_ssh1_key; | |
182 | int have_ssh2_key; | |
183 | u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; | |
184 | } sensitive_data; | |
185 | ||
186 | /* | |
187 | * Flag indicating whether the RSA server key needs to be regenerated. | |
188 | * Is set in the SIGALRM handler and cleared when the key is regenerated. | |
189 | */ | |
1e608e42 | 190 | static volatile sig_atomic_t key_do_regen = 0; |
3c0ef626 | 191 | |
192 | /* This is set to true when a signal is received. */ | |
1e608e42 | 193 | static volatile sig_atomic_t received_sighup = 0; |
194 | static volatile sig_atomic_t received_sigterm = 0; | |
3c0ef626 | 195 | |
196 | /* session identifier, used by RSA-auth */ | |
197 | u_char session_id[16]; | |
198 | ||
199 | /* same for ssh2 */ | |
200 | u_char *session_id2 = NULL; | |
70791e56 | 201 | u_int session_id2_len = 0; |
3c0ef626 | 202 | |
203 | /* record remote hostname or ip */ | |
204 | u_int utmp_len = MAXHOSTNAMELEN; | |
205 | ||
1e608e42 | 206 | /* options.max_startup sized array of fd ints */ |
207 | int *startup_pipes = NULL; | |
208 | int startup_pipe; /* in child */ | |
209 | ||
2980ea68 | 210 | /* variables used for privilege separation */ |
1c14df9e | 211 | int use_privsep; |
416fd2a8 | 212 | struct monitor *pmonitor = NULL; |
2980ea68 | 213 | |
70791e56 | 214 | /* message to be displayed after login */ |
215 | Buffer loginmsg; | |
216 | ||
416fd2a8 | 217 | /* global authentication context */ |
218 | Authctxt *the_authctxt = NULL; | |
219 | ||
3c0ef626 | 220 | /* Prototypes for various functions defined later in this file. */ |
221 | void destroy_sensitive_data(void); | |
2980ea68 | 222 | void demote_sensitive_data(void); |
3c0ef626 | 223 | |
224 | static void do_ssh1_kex(void); | |
225 | static void do_ssh2_kex(void); | |
226 | ||
227 | /* | |
228 | * Close all listening sockets | |
229 | */ | |
230 | static void | |
231 | close_listen_socks(void) | |
232 | { | |
233 | int i; | |
ff2d7a98 | 234 | |
3c0ef626 | 235 | for (i = 0; i < num_listen_socks; i++) |
236 | close(listen_socks[i]); | |
237 | num_listen_socks = -1; | |
238 | } | |
239 | ||
1e608e42 | 240 | static void |
241 | close_startup_pipes(void) | |
242 | { | |
243 | int i; | |
ff2d7a98 | 244 | |
1e608e42 | 245 | if (startup_pipes) |
246 | for (i = 0; i < options.max_startups; i++) | |
247 | if (startup_pipes[i] != -1) | |
248 | close(startup_pipes[i]); | |
249 | } | |
250 | ||
3c0ef626 | 251 | /* |
252 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
253 | * the effect is to reread the configuration file (and to regenerate | |
254 | * the server key). | |
255 | */ | |
256 | static void | |
257 | sighup_handler(int sig) | |
258 | { | |
1e608e42 | 259 | int save_errno = errno; |
260 | ||
3c0ef626 | 261 | received_sighup = 1; |
262 | signal(SIGHUP, sighup_handler); | |
1e608e42 | 263 | errno = save_errno; |
3c0ef626 | 264 | } |
265 | ||
266 | /* | |
267 | * Called from the main program after receiving SIGHUP. | |
268 | * Restarts the server. | |
269 | */ | |
270 | static void | |
271 | sighup_restart(void) | |
272 | { | |
70791e56 | 273 | logit("Received SIGHUP; restarting."); |
3c0ef626 | 274 | close_listen_socks(); |
1e608e42 | 275 | close_startup_pipes(); |
3c0ef626 | 276 | execv(saved_argv[0], saved_argv); |
70791e56 | 277 | logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], |
ff2d7a98 | 278 | strerror(errno)); |
3c0ef626 | 279 | exit(1); |
280 | } | |
281 | ||
282 | /* | |
283 | * Generic signal handler for terminating signals in the master daemon. | |
284 | */ | |
285 | static void | |
286 | sigterm_handler(int sig) | |
287 | { | |
288 | received_sigterm = sig; | |
289 | } | |
290 | ||
291 | /* | |
292 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
293 | * reap any zombies left by exited children. | |
294 | */ | |
295 | static void | |
296 | main_sigchld_handler(int sig) | |
297 | { | |
298 | int save_errno = errno; | |
ff2d7a98 | 299 | pid_t pid; |
3c0ef626 | 300 | int status; |
301 | ||
2980ea68 | 302 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || |
303 | (pid < 0 && errno == EINTR)) | |
3c0ef626 | 304 | ; |
305 | ||
306 | signal(SIGCHLD, main_sigchld_handler); | |
307 | errno = save_errno; | |
308 | } | |
309 | ||
310 | /* | |
311 | * Signal handler for the alarm after the login grace period has expired. | |
312 | */ | |
313 | static void | |
314 | grace_alarm_handler(int sig) | |
315 | { | |
316 | /* XXX no idea how fix this signal handler */ | |
317 | ||
416fd2a8 | 318 | if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) |
319 | kill(pmonitor->m_pid, SIGALRM); | |
320 | ||
3c0ef626 | 321 | /* Log error and exit. */ |
e54b3d7c | 322 | fatal("Timeout before authentication for %s", get_remote_ipaddr()); |
3c0ef626 | 323 | } |
324 | ||
325 | /* | |
326 | * Signal handler for the key regeneration alarm. Note that this | |
327 | * alarm only occurs in the daemon waiting for connections, and it does not | |
328 | * do anything with the private key or random state before forking. | |
329 | * Thus there should be no concurrency control/asynchronous execution | |
330 | * problems. | |
331 | */ | |
332 | static void | |
333 | generate_ephemeral_server_key(void) | |
334 | { | |
e54b3d7c | 335 | u_int32_t rnd = 0; |
3c0ef626 | 336 | int i; |
337 | ||
338 | verbose("Generating %s%d bit RSA key.", | |
339 | sensitive_data.server_key ? "new " : "", options.server_key_bits); | |
340 | if (sensitive_data.server_key != NULL) | |
341 | key_free(sensitive_data.server_key); | |
342 | sensitive_data.server_key = key_generate(KEY_RSA1, | |
343 | options.server_key_bits); | |
344 | verbose("RSA key generation complete."); | |
345 | ||
346 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
347 | if (i % 4 == 0) | |
e54b3d7c | 348 | rnd = arc4random(); |
349 | sensitive_data.ssh1_cookie[i] = rnd & 0xff; | |
350 | rnd >>= 8; | |
3c0ef626 | 351 | } |
352 | arc4random_stir(); | |
353 | } | |
354 | ||
355 | static void | |
356 | key_regeneration_alarm(int sig) | |
357 | { | |
358 | int save_errno = errno; | |
ff2d7a98 | 359 | |
3c0ef626 | 360 | signal(SIGALRM, SIG_DFL); |
361 | errno = save_errno; | |
362 | key_do_regen = 1; | |
363 | } | |
364 | ||
365 | static void | |
366 | sshd_exchange_identification(int sock_in, int sock_out) | |
367 | { | |
368 | int i, mismatch; | |
369 | int remote_major, remote_minor; | |
370 | int major, minor; | |
371 | char *s; | |
372 | char buf[256]; /* Must not be larger than remote_version. */ | |
373 | char remote_version[256]; /* Must be at least as big as buf. */ | |
374 | ||
375 | if ((options.protocol & SSH_PROTO_1) && | |
376 | (options.protocol & SSH_PROTO_2)) { | |
377 | major = PROTOCOL_MAJOR_1; | |
378 | minor = 99; | |
379 | } else if (options.protocol & SSH_PROTO_2) { | |
380 | major = PROTOCOL_MAJOR_2; | |
381 | minor = PROTOCOL_MINOR_2; | |
382 | } else { | |
383 | major = PROTOCOL_MAJOR_1; | |
384 | minor = PROTOCOL_MINOR_1; | |
385 | } | |
386 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
387 | server_version_string = xstrdup(buf); | |
388 | ||
70791e56 | 389 | /* Send our protocol version identification. */ |
390 | if (atomicio(vwrite, sock_out, server_version_string, | |
391 | strlen(server_version_string)) | |
392 | != strlen(server_version_string)) { | |
393 | logit("Could not write ident string to %s", get_remote_ipaddr()); | |
416fd2a8 | 394 | cleanup_exit(255); |
70791e56 | 395 | } |
396 | ||
397 | /* Read other sides version identification. */ | |
398 | memset(buf, 0, sizeof(buf)); | |
399 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
400 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { | |
401 | logit("Did not receive identification string from %s", | |
402 | get_remote_ipaddr()); | |
416fd2a8 | 403 | cleanup_exit(255); |
3c0ef626 | 404 | } |
70791e56 | 405 | if (buf[i] == '\r') { |
406 | buf[i] = 0; | |
407 | /* Kludge for F-Secure Macintosh < 1.0.2 */ | |
408 | if (i == 12 && | |
409 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
3c0ef626 | 410 | break; |
70791e56 | 411 | continue; |
412 | } | |
413 | if (buf[i] == '\n') { | |
414 | buf[i] = 0; | |
415 | break; | |
3c0ef626 | 416 | } |
3c0ef626 | 417 | } |
70791e56 | 418 | buf[sizeof(buf) - 1] = 0; |
419 | client_version_string = xstrdup(buf); | |
3c0ef626 | 420 | |
421 | /* | |
422 | * Check that the versions match. In future this might accept | |
423 | * several versions and set appropriate flags to handle them. | |
424 | */ | |
425 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
426 | &remote_major, &remote_minor, remote_version) != 3) { | |
427 | s = "Protocol mismatch.\n"; | |
70791e56 | 428 | (void) atomicio(vwrite, sock_out, s, strlen(s)); |
3c0ef626 | 429 | close(sock_in); |
430 | close(sock_out); | |
70791e56 | 431 | logit("Bad protocol version identification '%.100s' from %s", |
3c0ef626 | 432 | client_version_string, get_remote_ipaddr()); |
416fd2a8 | 433 | cleanup_exit(255); |
3c0ef626 | 434 | } |
435 | debug("Client protocol version %d.%d; client software version %.100s", | |
1e608e42 | 436 | remote_major, remote_minor, remote_version); |
3c0ef626 | 437 | |
438 | compat_datafellows(remote_version); | |
439 | ||
e54b3d7c | 440 | if (datafellows & SSH_BUG_PROBE) { |
70791e56 | 441 | logit("probed from %s with %s. Don't panic.", |
e54b3d7c | 442 | get_remote_ipaddr(), client_version_string); |
416fd2a8 | 443 | cleanup_exit(255); |
e54b3d7c | 444 | } |
445 | ||
3c0ef626 | 446 | if (datafellows & SSH_BUG_SCANNER) { |
70791e56 | 447 | logit("scanned from %s with %s. Don't panic.", |
3c0ef626 | 448 | get_remote_ipaddr(), client_version_string); |
416fd2a8 | 449 | cleanup_exit(255); |
3c0ef626 | 450 | } |
451 | ||
452 | mismatch = 0; | |
1e608e42 | 453 | switch (remote_major) { |
3c0ef626 | 454 | case 1: |
455 | if (remote_minor == 99) { | |
456 | if (options.protocol & SSH_PROTO_2) | |
457 | enable_compat20(); | |
458 | else | |
459 | mismatch = 1; | |
460 | break; | |
461 | } | |
462 | if (!(options.protocol & SSH_PROTO_1)) { | |
463 | mismatch = 1; | |
464 | break; | |
465 | } | |
466 | if (remote_minor < 3) { | |
467 | packet_disconnect("Your ssh version is too old and " | |
468 | "is no longer supported. Please install a newer version."); | |
469 | } else if (remote_minor == 3) { | |
470 | /* note that this disables agent-forwarding */ | |
471 | enable_compat13(); | |
472 | } | |
473 | break; | |
474 | case 2: | |
475 | if (options.protocol & SSH_PROTO_2) { | |
476 | enable_compat20(); | |
477 | break; | |
478 | } | |
479 | /* FALLTHROUGH */ | |
480 | default: | |
481 | mismatch = 1; | |
482 | break; | |
483 | } | |
484 | chop(server_version_string); | |
485 | debug("Local version string %.200s", server_version_string); | |
486 | ||
487 | if (mismatch) { | |
488 | s = "Protocol major versions differ.\n"; | |
70791e56 | 489 | (void) atomicio(vwrite, sock_out, s, strlen(s)); |
3c0ef626 | 490 | close(sock_in); |
491 | close(sock_out); | |
70791e56 | 492 | logit("Protocol major versions differ for %s: %.200s vs. %.200s", |
3c0ef626 | 493 | get_remote_ipaddr(), |
494 | server_version_string, client_version_string); | |
416fd2a8 | 495 | cleanup_exit(255); |
3c0ef626 | 496 | } |
497 | } | |
498 | ||
3c0ef626 | 499 | /* Destroy the host and server keys. They will no longer be needed. */ |
500 | void | |
501 | destroy_sensitive_data(void) | |
502 | { | |
503 | int i; | |
504 | ||
505 | if (sensitive_data.server_key) { | |
506 | key_free(sensitive_data.server_key); | |
507 | sensitive_data.server_key = NULL; | |
508 | } | |
1e608e42 | 509 | for (i = 0; i < options.num_host_key_files; i++) { |
3c0ef626 | 510 | if (sensitive_data.host_keys[i]) { |
511 | key_free(sensitive_data.host_keys[i]); | |
512 | sensitive_data.host_keys[i] = NULL; | |
513 | } | |
514 | } | |
515 | sensitive_data.ssh1_host_key = NULL; | |
516 | memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); | |
517 | } | |
518 | ||
2980ea68 | 519 | /* Demote private to public keys for network child */ |
520 | void | |
521 | demote_sensitive_data(void) | |
522 | { | |
523 | Key *tmp; | |
524 | int i; | |
525 | ||
526 | if (sensitive_data.server_key) { | |
527 | tmp = key_demote(sensitive_data.server_key); | |
528 | key_free(sensitive_data.server_key); | |
529 | sensitive_data.server_key = tmp; | |
530 | } | |
531 | ||
532 | for (i = 0; i < options.num_host_key_files; i++) { | |
533 | if (sensitive_data.host_keys[i]) { | |
534 | tmp = key_demote(sensitive_data.host_keys[i]); | |
535 | key_free(sensitive_data.host_keys[i]); | |
536 | sensitive_data.host_keys[i] = tmp; | |
537 | if (tmp->type == KEY_RSA1) | |
538 | sensitive_data.ssh1_host_key = tmp; | |
539 | } | |
540 | } | |
541 | ||
542 | /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ | |
543 | } | |
544 | ||
545 | static void | |
546 | privsep_preauth_child(void) | |
547 | { | |
e54b3d7c | 548 | u_int32_t rnd[256]; |
549 | gid_t gidset[1]; | |
2980ea68 | 550 | struct passwd *pw; |
ff2d7a98 | 551 | int i; |
2980ea68 | 552 | |
553 | /* Enable challenge-response authentication for privilege separation */ | |
554 | privsep_challenge_enable(); | |
555 | ||
556 | for (i = 0; i < 256; i++) | |
e54b3d7c | 557 | rnd[i] = arc4random(); |
558 | RAND_seed(rnd, sizeof(rnd)); | |
2980ea68 | 559 | |
560 | /* Demote the private keys to public keys. */ | |
561 | demote_sensitive_data(); | |
562 | ||
563 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
564 | fatal("Privilege separation user %s does not exist", | |
565 | SSH_PRIVSEP_USER); | |
566 | memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); | |
567 | endpwent(); | |
568 | ||
e54b3d7c | 569 | /* Change our root directory */ |
2980ea68 | 570 | if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) |
571 | fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, | |
572 | strerror(errno)); | |
573 | if (chdir("/") == -1) | |
574 | fatal("chdir(\"/\"): %s", strerror(errno)); | |
575 | ||
576 | /* Drop our privileges */ | |
577 | debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, | |
578 | (u_int)pw->pw_gid); | |
ff2d7a98 | 579 | #if 0 |
580 | /* XXX not ready, to heavy after chroot */ | |
2980ea68 | 581 | do_setusercontext(pw); |
ff2d7a98 | 582 | #else |
583 | gidset[0] = pw->pw_gid; | |
ff2d7a98 | 584 | if (setgroups(1, gidset) < 0) |
585 | fatal("setgroups: %.100s", strerror(errno)); | |
586 | permanently_set_uid(pw); | |
587 | #endif | |
2980ea68 | 588 | } |
589 | ||
416fd2a8 | 590 | static int |
591 | privsep_preauth(Authctxt *authctxt) | |
2980ea68 | 592 | { |
2980ea68 | 593 | int status; |
594 | pid_t pid; | |
595 | ||
596 | /* Set up unprivileged child process to deal with network data */ | |
597 | pmonitor = monitor_init(); | |
598 | /* Store a pointer to the kex for later rekeying */ | |
599 | pmonitor->m_pkex = &xxx_kex; | |
600 | ||
601 | pid = fork(); | |
602 | if (pid == -1) { | |
603 | fatal("fork of unprivileged child failed"); | |
604 | } else if (pid != 0) { | |
ff2d7a98 | 605 | debug2("Network child is on pid %ld", (long)pid); |
2980ea68 | 606 | |
607 | close(pmonitor->m_recvfd); | |
416fd2a8 | 608 | pmonitor->m_pid = pid; |
609 | monitor_child_preauth(authctxt, pmonitor); | |
2980ea68 | 610 | close(pmonitor->m_sendfd); |
611 | ||
612 | /* Sync memory */ | |
613 | monitor_sync(pmonitor); | |
614 | ||
615 | /* Wait for the child's exit status */ | |
616 | while (waitpid(pid, &status, 0) < 0) | |
617 | if (errno != EINTR) | |
618 | break; | |
416fd2a8 | 619 | return (1); |
2980ea68 | 620 | } else { |
621 | /* child */ | |
622 | ||
623 | close(pmonitor->m_sendfd); | |
624 | ||
625 | /* Demote the child */ | |
626 | if (getuid() == 0 || geteuid() == 0) | |
627 | privsep_preauth_child(); | |
628 | setproctitle("%s", "[net]"); | |
629 | } | |
416fd2a8 | 630 | return (0); |
2980ea68 | 631 | } |
632 | ||
633 | static void | |
634 | privsep_postauth(Authctxt *authctxt) | |
635 | { | |
e54b3d7c | 636 | #ifdef DISABLE_FD_PASSING |
ff2d7a98 | 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; |
416fd2a8 | 685 | const char *p; |
686 | char *ret; | |
3c0ef626 | 687 | int i; |
1e608e42 | 688 | |
689 | buffer_init(&b); | |
690 | for (i = 0; i < options.num_host_key_files; i++) { | |
3c0ef626 | 691 | Key *key = sensitive_data.host_keys[i]; |
692 | if (key == NULL) | |
693 | continue; | |
1e608e42 | 694 | switch (key->type) { |
3c0ef626 | 695 | case KEY_RSA: |
696 | case KEY_DSA: | |
1e608e42 | 697 | if (buffer_len(&b) > 0) |
698 | buffer_append(&b, ",", 1); | |
699 | p = key_ssh_name(key); | |
700 | buffer_append(&b, p, strlen(p)); | |
3c0ef626 | 701 | break; |
702 | } | |
703 | } | |
1e608e42 | 704 | buffer_append(&b, "\0", 1); |
416fd2a8 | 705 | ret = xstrdup(buffer_ptr(&b)); |
1e608e42 | 706 | buffer_free(&b); |
416fd2a8 | 707 | debug("list_hostkey_types: %s", ret); |
708 | return ret; | |
3c0ef626 | 709 | } |
710 | ||
2980ea68 | 711 | Key * |
3c0ef626 | 712 | get_hostkey_by_type(int type) |
713 | { | |
714 | int i; | |
ff2d7a98 | 715 | |
1e608e42 | 716 | for (i = 0; i < options.num_host_key_files; i++) { |
3c0ef626 | 717 | Key *key = sensitive_data.host_keys[i]; |
718 | if (key != NULL && key->type == type) | |
719 | return key; | |
720 | } | |
721 | return NULL; | |
722 | } | |
723 | ||
2980ea68 | 724 | Key * |
725 | get_hostkey_by_index(int ind) | |
726 | { | |
727 | if (ind < 0 || ind >= options.num_host_key_files) | |
728 | return (NULL); | |
729 | return (sensitive_data.host_keys[ind]); | |
730 | } | |
731 | ||
732 | int | |
733 | get_hostkey_index(Key *key) | |
734 | { | |
735 | int i; | |
ff2d7a98 | 736 | |
2980ea68 | 737 | for (i = 0; i < options.num_host_key_files; i++) { |
738 | if (key == sensitive_data.host_keys[i]) | |
739 | return (i); | |
740 | } | |
741 | return (-1); | |
742 | } | |
743 | ||
3c0ef626 | 744 | /* |
745 | * returns 1 if connection should be dropped, 0 otherwise. | |
746 | * dropping starts at connection #max_startups_begin with a probability | |
747 | * of (max_startups_rate/100). the probability increases linearly until | |
748 | * all connections are dropped for startups > max_startups | |
749 | */ | |
750 | static int | |
751 | drop_connection(int startups) | |
752 | { | |
753 | double p, r; | |
754 | ||
755 | if (startups < options.max_startups_begin) | |
756 | return 0; | |
757 | if (startups >= options.max_startups) | |
758 | return 1; | |
759 | if (options.max_startups_rate == 100) | |
760 | return 1; | |
761 | ||
762 | p = 100 - options.max_startups_rate; | |
763 | p *= startups - options.max_startups_begin; | |
764 | p /= (double) (options.max_startups - options.max_startups_begin); | |
765 | p += options.max_startups_rate; | |
766 | p /= 100.0; | |
767 | r = arc4random() / (double) UINT_MAX; | |
768 | ||
769 | debug("drop_connection: p %g, r %g", p, r); | |
770 | return (r < p) ? 1 : 0; | |
771 | } | |
772 | ||
1e608e42 | 773 | static void |
774 | usage(void) | |
775 | { | |
416fd2a8 | 776 | fprintf(stderr, "sshd version %s, %s\n", |
777 | SSH_VERSION, SSLeay_version(SSLEAY_VERSION)); | |
1e608e42 | 778 | fprintf(stderr, "Usage: %s [options]\n", __progname); |
779 | fprintf(stderr, "Options:\n"); | |
780 | fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE); | |
781 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); | |
782 | fprintf(stderr, " -i Started from inetd\n"); | |
783 | fprintf(stderr, " -D Do not fork into daemon mode\n"); | |
784 | fprintf(stderr, " -t Only test configuration file and keys\n"); | |
785 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
786 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
787 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
788 | fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n"); | |
789 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
790 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
791 | _PATH_HOST_KEY_FILE); | |
792 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); | |
793 | fprintf(stderr, " -4 Use IPv4 only\n"); | |
794 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
795 | fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n"); | |
796 | exit(1); | |
797 | } | |
3c0ef626 | 798 | |
799 | /* | |
800 | * Main program for the daemon. | |
801 | */ | |
802 | int | |
803 | main(int ac, char **av) | |
804 | { | |
805 | extern char *optarg; | |
806 | extern int optind; | |
807 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; | |
808 | pid_t pid; | |
809 | socklen_t fromlen; | |
810 | fd_set *fdset; | |
811 | struct sockaddr_storage from; | |
812 | const char *remote_ip; | |
813 | int remote_port; | |
814 | FILE *f; | |
3c0ef626 | 815 | struct addrinfo *ai; |
816 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
416fd2a8 | 817 | char *line; |
3c0ef626 | 818 | int listen_sock, maxfd; |
819 | int startup_p[2]; | |
820 | int startups = 0; | |
821 | Key *key; | |
416fd2a8 | 822 | Authctxt *authctxt; |
3c0ef626 | 823 | int ret, key_used = 0; |
824 | ||
2980ea68 | 825 | #ifdef HAVE_SECUREWARE |
826 | (void)set_auth_parameters(ac, av); | |
827 | #endif | |
70791e56 | 828 | __progname = ssh_get_progname(av[0]); |
ae43c103 | 829 | init_pathnames(); |
004706ea | 830 | config_file_name = _PATH_SERVER_CONFIG_FILE; |
3c0ef626 | 831 | init_rng(); |
832 | ||
1c14df9e | 833 | /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ |
3c0ef626 | 834 | saved_argc = ac; |
70791e56 | 835 | saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1)); |
1c14df9e | 836 | for (i = 0; i < ac; i++) |
837 | saved_argv[i] = xstrdup(av[i]); | |
70791e56 | 838 | saved_argv[i] = NULL; |
1c14df9e | 839 | |
840 | #ifndef HAVE_SETPROCTITLE | |
841 | /* Prepare for later setproctitle emulation */ | |
842 | compat_init_setproctitle(ac, av); | |
70791e56 | 843 | av = saved_argv; |
1c14df9e | 844 | #endif |
3c0ef626 | 845 | |
846 | /* Initialize configuration options to their default values. */ | |
847 | initialize_server_options(&options); | |
848 | ||
849 | /* Parse command-line arguments. */ | |
70791e56 | 850 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqtQ46")) != -1) { |
3c0ef626 | 851 | switch (opt) { |
852 | case '4': | |
853 | IPv4or6 = AF_INET; | |
854 | break; | |
855 | case '6': | |
856 | IPv4or6 = AF_INET6; | |
857 | break; | |
858 | case 'f': | |
859 | config_file_name = optarg; | |
860 | break; | |
861 | case 'd': | |
70791e56 | 862 | if (debug_flag == 0) { |
3c0ef626 | 863 | debug_flag = 1; |
864 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
70791e56 | 865 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) |
3c0ef626 | 866 | options.log_level++; |
3c0ef626 | 867 | break; |
868 | case 'D': | |
869 | no_daemon_flag = 1; | |
870 | break; | |
871 | case 'e': | |
872 | log_stderr = 1; | |
873 | break; | |
874 | case 'i': | |
875 | inetd_flag = 1; | |
876 | break; | |
877 | case 'Q': | |
878 | /* ignored */ | |
879 | break; | |
880 | case 'q': | |
881 | options.log_level = SYSLOG_LEVEL_QUIET; | |
882 | break; | |
883 | case 'b': | |
884 | options.server_key_bits = atoi(optarg); | |
885 | break; | |
886 | case 'p': | |
887 | options.ports_from_cmdline = 1; | |
888 | if (options.num_ports >= MAX_PORTS) { | |
889 | fprintf(stderr, "too many ports.\n"); | |
890 | exit(1); | |
891 | } | |
892 | options.ports[options.num_ports++] = a2port(optarg); | |
893 | if (options.ports[options.num_ports-1] == 0) { | |
894 | fprintf(stderr, "Bad port number.\n"); | |
895 | exit(1); | |
896 | } | |
897 | break; | |
898 | case 'g': | |
899 | if ((options.login_grace_time = convtime(optarg)) == -1) { | |
900 | fprintf(stderr, "Invalid login grace time.\n"); | |
901 | exit(1); | |
902 | } | |
903 | break; | |
904 | case 'k': | |
905 | if ((options.key_regeneration_time = convtime(optarg)) == -1) { | |
906 | fprintf(stderr, "Invalid key regeneration interval.\n"); | |
907 | exit(1); | |
908 | } | |
909 | break; | |
910 | case 'h': | |
911 | if (options.num_host_key_files >= MAX_HOSTKEYS) { | |
912 | fprintf(stderr, "too many host keys.\n"); | |
913 | exit(1); | |
914 | } | |
915 | options.host_key_files[options.num_host_key_files++] = optarg; | |
916 | break; | |
3c0ef626 | 917 | case 't': |
918 | test_flag = 1; | |
919 | break; | |
920 | case 'u': | |
921 | utmp_len = atoi(optarg); | |
e54b3d7c | 922 | if (utmp_len > MAXHOSTNAMELEN) { |
923 | fprintf(stderr, "Invalid utmp length.\n"); | |
924 | exit(1); | |
925 | } | |
3c0ef626 | 926 | break; |
1e608e42 | 927 | case 'o': |
416fd2a8 | 928 | line = xstrdup(optarg); |
929 | if (process_server_config_line(&options, line, | |
1e608e42 | 930 | "command-line", 0) != 0) |
931 | exit(1); | |
416fd2a8 | 932 | xfree(line); |
1e608e42 | 933 | break; |
3c0ef626 | 934 | case '?': |
935 | default: | |
1e608e42 | 936 | usage(); |
937 | break; | |
3c0ef626 | 938 | } |
939 | } | |
940 | SSLeay_add_all_algorithms(); | |
941 | channel_set_af(IPv4or6); | |
942 | ||
943 | /* | |
944 | * Force logging to stderr until we have loaded the private host | |
945 | * key (unless started from inetd) | |
946 | */ | |
947 | log_init(__progname, | |
1e608e42 | 948 | options.log_level == SYSLOG_LEVEL_NOT_SET ? |
949 | SYSLOG_LEVEL_INFO : options.log_level, | |
950 | options.log_facility == SYSLOG_FACILITY_NOT_SET ? | |
951 | SYSLOG_FACILITY_AUTH : options.log_facility, | |
1c14df9e | 952 | log_stderr || !inetd_flag); |
3c0ef626 | 953 | |
e54b3d7c | 954 | #ifdef _UNICOS |
3c0ef626 | 955 | /* Cray can define user privs drop all prives now! |
956 | * Not needed on PRIV_SU systems! | |
957 | */ | |
958 | drop_cray_privs(); | |
959 | #endif | |
960 | ||
961 | seed_rng(); | |
962 | ||
963 | /* Read server configuration options from the configuration file. */ | |
964 | read_server_config(&options, config_file_name); | |
965 | ||
966 | /* Fill in default values for those options not explicitly set. */ | |
967 | fill_default_server_options(&options); | |
968 | ||
969 | /* Check that there are no remaining arguments. */ | |
970 | if (optind < ac) { | |
971 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
972 | exit(1); | |
973 | } | |
974 | ||
975 | debug("sshd version %.100s", SSH_VERSION); | |
976 | ||
977 | /* load private host keys */ | |
e54b3d7c | 978 | sensitive_data.host_keys = xmalloc(options.num_host_key_files * |
979 | sizeof(Key *)); | |
1e608e42 | 980 | for (i = 0; i < options.num_host_key_files; i++) |
3c0ef626 | 981 | sensitive_data.host_keys[i] = NULL; |
982 | sensitive_data.server_key = NULL; | |
983 | sensitive_data.ssh1_host_key = NULL; | |
984 | sensitive_data.have_ssh1_key = 0; | |
985 | sensitive_data.have_ssh2_key = 0; | |
986 | ||
1e608e42 | 987 | for (i = 0; i < options.num_host_key_files; i++) { |
3c0ef626 | 988 | key = key_load_private(options.host_key_files[i], "", NULL); |
989 | sensitive_data.host_keys[i] = key; | |
990 | if (key == NULL) { | |
991 | error("Could not load host key: %s", | |
992 | options.host_key_files[i]); | |
993 | sensitive_data.host_keys[i] = NULL; | |
994 | continue; | |
995 | } | |
1e608e42 | 996 | switch (key->type) { |
3c0ef626 | 997 | case KEY_RSA1: |
998 | sensitive_data.ssh1_host_key = key; | |
999 | sensitive_data.have_ssh1_key = 1; | |
1000 | break; | |
1001 | case KEY_RSA: | |
1002 | case KEY_DSA: | |
1003 | sensitive_data.have_ssh2_key = 1; | |
1004 | break; | |
1005 | } | |
1006 | debug("private host key: #%d type %d %s", i, key->type, | |
1007 | key_type(key)); | |
1008 | } | |
1009 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
70791e56 | 1010 | logit("Disabling protocol version 1. Could not load host key"); |
3c0ef626 | 1011 | options.protocol &= ~SSH_PROTO_1; |
1012 | } | |
5598e598 | 1013 | #ifndef GSSAPI |
1014 | /* The GSSAPI key exchange can run without a host key */ | |
3c0ef626 | 1015 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { |
70791e56 | 1016 | logit("Disabling protocol version 2. Could not load host key"); |
3c0ef626 | 1017 | options.protocol &= ~SSH_PROTO_2; |
1018 | } | |
5598e598 | 1019 | #endif |
3c0ef626 | 1020 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { |
70791e56 | 1021 | logit("sshd: no hostkeys available -- exiting."); |
3c0ef626 | 1022 | exit(1); |
1023 | } | |
1024 | ||
1025 | /* Check certain values for sanity. */ | |
1026 | if (options.protocol & SSH_PROTO_1) { | |
1027 | if (options.server_key_bits < 512 || | |
1028 | options.server_key_bits > 32768) { | |
1029 | fprintf(stderr, "Bad server key size.\n"); | |
1030 | exit(1); | |
1031 | } | |
1032 | /* | |
1033 | * Check that server and host key lengths differ sufficiently. This | |
1034 | * is necessary to make double encryption work with rsaref. Oh, I | |
1035 | * hate software patents. I dont know if this can go? Niels | |
1036 | */ | |
1037 | if (options.server_key_bits > | |
ff2d7a98 | 1038 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - |
1039 | SSH_KEY_BITS_RESERVED && options.server_key_bits < | |
1040 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1041 | SSH_KEY_BITS_RESERVED) { | |
3c0ef626 | 1042 | options.server_key_bits = |
ff2d7a98 | 1043 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + |
1044 | SSH_KEY_BITS_RESERVED; | |
3c0ef626 | 1045 | debug("Forcing server key to %d bits to make it differ from host key.", |
1046 | options.server_key_bits); | |
1047 | } | |
1048 | } | |
1049 | ||
ff2d7a98 | 1050 | if (use_privsep) { |
1051 | struct passwd *pw; | |
1052 | struct stat st; | |
1053 | ||
1054 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
1055 | fatal("Privilege separation user %s does not exist", | |
1056 | SSH_PRIVSEP_USER); | |
1057 | if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || | |
1058 | (S_ISDIR(st.st_mode) == 0)) | |
1059 | fatal("Missing privilege separation directory: %s", | |
1060 | _PATH_PRIVSEP_CHROOT_DIR); | |
e54b3d7c | 1061 | |
1062 | #ifdef HAVE_CYGWIN | |
1063 | if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && | |
1064 | (st.st_uid != getuid () || | |
1065 | (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) | |
1066 | #else | |
ff2d7a98 | 1067 | if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) |
e54b3d7c | 1068 | #endif |
1c14df9e | 1069 | fatal("%s must be owned by root and not group or " |
1070 | "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); | |
ff2d7a98 | 1071 | } |
1072 | ||
3c0ef626 | 1073 | /* Configuration looks good, so exit if in test mode. */ |
1074 | if (test_flag) | |
1075 | exit(0); | |
1076 | ||
2980ea68 | 1077 | /* |
1078 | * Clear out any supplemental groups we may have inherited. This | |
1079 | * prevents inadvertent creation of files with bad modes (in the | |
416fd2a8 | 1080 | * portable version at least, it's certainly possible for PAM |
1081 | * to create a file, and we can't control the code in every | |
2980ea68 | 1082 | * module which might be used). |
1083 | */ | |
1084 | if (setgroups(0, NULL) < 0) | |
1085 | debug("setgroups() failed: %.200s", strerror(errno)); | |
3c0ef626 | 1086 | |
1087 | /* Initialize the log (it is reinitialized below in case we forked). */ | |
1088 | if (debug_flag && !inetd_flag) | |
1089 | log_stderr = 1; | |
1090 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1091 | ||
1092 | /* | |
1093 | * If not in debugging mode, and not started from inetd, disconnect | |
1094 | * from the controlling terminal, and fork. The original process | |
1095 | * exits. | |
1096 | */ | |
1097 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { | |
1098 | #ifdef TIOCNOTTY | |
1099 | int fd; | |
1100 | #endif /* TIOCNOTTY */ | |
1101 | if (daemon(0, 0) < 0) | |
1102 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1103 | ||
1104 | /* Disconnect from the controlling tty. */ | |
1105 | #ifdef TIOCNOTTY | |
1106 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); | |
1107 | if (fd >= 0) { | |
1108 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
1109 | close(fd); | |
1110 | } | |
1111 | #endif /* TIOCNOTTY */ | |
1112 | } | |
1113 | /* Reinitialize the log (because of the fork above). */ | |
1114 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1115 | ||
1116 | /* Initialize the random number generator. */ | |
1117 | arc4random_stir(); | |
1118 | ||
1119 | /* Chdir to the root directory so that the current disk can be | |
1120 | unmounted if desired. */ | |
1121 | chdir("/"); | |
1e608e42 | 1122 | |
416fd2a8 | 1123 | #ifndef HAVE_CYGWIN |
55fe48cf | 1124 | #ifndef GSI /* GSI gets configuration from environment! */ |
416fd2a8 | 1125 | /* Clear environment */ |
1126 | environ[0] = NULL; | |
55fe48cf | 1127 | #endif |
416fd2a8 | 1128 | #endif |
1129 | ||
3c0ef626 | 1130 | /* ignore SIGPIPE */ |
1131 | signal(SIGPIPE, SIG_IGN); | |
1132 | ||
1133 | /* Start listening for a socket, unless started from inetd. */ | |
1134 | if (inetd_flag) { | |
1135 | int s1; | |
1136 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ | |
1137 | dup(s1); | |
1138 | sock_in = dup(0); | |
1139 | sock_out = dup(1); | |
1140 | startup_pipe = -1; | |
1141 | /* | |
1142 | * We intentionally do not close the descriptors 0, 1, and 2 | |
1143 | * as our code for setting the descriptors won\'t work if | |
1144 | * ttyfd happens to be one of those. | |
1145 | */ | |
1146 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); | |
1147 | if (options.protocol & SSH_PROTO_1) | |
1148 | generate_ephemeral_server_key(); | |
1149 | } else { | |
1150 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { | |
1151 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
1152 | continue; | |
1153 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
1154 | fatal("Too many listen sockets. " | |
1155 | "Enlarge MAX_LISTEN_SOCKS"); | |
1156 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
1157 | ntop, sizeof(ntop), strport, sizeof(strport), | |
1158 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
1159 | error("getnameinfo failed"); | |
1160 | continue; | |
1161 | } | |
1162 | /* Create socket for listening. */ | |
70791e56 | 1163 | listen_sock = socket(ai->ai_family, ai->ai_socktype, |
1164 | ai->ai_protocol); | |
3c0ef626 | 1165 | if (listen_sock < 0) { |
1166 | /* kernel may not support ipv6 */ | |
1167 | verbose("socket: %.100s", strerror(errno)); | |
1168 | continue; | |
1169 | } | |
1170 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
1171 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
1172 | close(listen_sock); | |
1173 | continue; | |
1174 | } | |
1175 | /* | |
e54b3d7c | 1176 | * Set socket options. |
1177 | * Allow local port reuse in TIME_WAIT. | |
3c0ef626 | 1178 | */ |
e54b3d7c | 1179 | if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, |
1180 | &on, sizeof(on)) == -1) | |
1181 | error("setsockopt SO_REUSEADDR: %s", strerror(errno)); | |
3c0ef626 | 1182 | |
1183 | debug("Bind to port %s on %s.", strport, ntop); | |
1184 | ||
1185 | /* Bind the socket to the desired port. */ | |
1186 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { | |
1187 | if (!ai->ai_next) | |
1188 | error("Bind to port %s on %s failed: %.200s.", | |
1189 | strport, ntop, strerror(errno)); | |
1190 | close(listen_sock); | |
1191 | continue; | |
1192 | } | |
1193 | listen_socks[num_listen_socks] = listen_sock; | |
1194 | num_listen_socks++; | |
1195 | ||
1196 | /* Start listening on the port. */ | |
70791e56 | 1197 | logit("Server listening on %s port %s.", ntop, strport); |
416fd2a8 | 1198 | if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) |
3c0ef626 | 1199 | fatal("listen: %.100s", strerror(errno)); |
1200 | ||
1201 | } | |
1202 | freeaddrinfo(options.listen_addrs); | |
1203 | ||
1204 | if (!num_listen_socks) | |
1205 | fatal("Cannot bind any address."); | |
1206 | ||
1207 | if (options.protocol & SSH_PROTO_1) | |
1208 | generate_ephemeral_server_key(); | |
1209 | ||
1210 | /* | |
1211 | * Arrange to restart on SIGHUP. The handler needs | |
1212 | * listen_sock. | |
1213 | */ | |
1214 | signal(SIGHUP, sighup_handler); | |
1215 | ||
1216 | signal(SIGTERM, sigterm_handler); | |
1217 | signal(SIGQUIT, sigterm_handler); | |
1218 | ||
1219 | /* Arrange SIGCHLD to be caught. */ | |
1220 | signal(SIGCHLD, main_sigchld_handler); | |
1221 | ||
1222 | /* Write out the pid file after the sigterm handler is setup */ | |
1223 | if (!debug_flag) { | |
1224 | /* | |
1225 | * Record our pid in /var/run/sshd.pid to make it | |
1226 | * easier to kill the correct sshd. We don't want to | |
1227 | * do this before the bind above because the bind will | |
1228 | * fail if there already is a daemon, and this will | |
1229 | * overwrite any old pid in the file. | |
1230 | */ | |
1231 | f = fopen(options.pid_file, "wb"); | |
70791e56 | 1232 | if (f == NULL) { |
1233 | error("Couldn't create pid file \"%s\": %s", | |
1234 | options.pid_file, strerror(errno)); | |
1235 | } else { | |
ff2d7a98 | 1236 | fprintf(f, "%ld\n", (long) getpid()); |
3c0ef626 | 1237 | fclose(f); |
1238 | } | |
1239 | } | |
1240 | ||
1241 | /* setup fd set for listen */ | |
1242 | fdset = NULL; | |
1243 | maxfd = 0; | |
1244 | for (i = 0; i < num_listen_socks; i++) | |
1245 | if (listen_socks[i] > maxfd) | |
1246 | maxfd = listen_socks[i]; | |
1247 | /* pipes connected to unauthenticated childs */ | |
1248 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
1249 | for (i = 0; i < options.max_startups; i++) | |
1250 | startup_pipes[i] = -1; | |
1251 | ||
1252 | /* | |
1253 | * Stay listening for connections until the system crashes or | |
1254 | * the daemon is killed with a signal. | |
1255 | */ | |
1256 | for (;;) { | |
1257 | if (received_sighup) | |
1258 | sighup_restart(); | |
1259 | if (fdset != NULL) | |
1260 | xfree(fdset); | |
1261 | fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); | |
1262 | fdset = (fd_set *)xmalloc(fdsetsz); | |
1263 | memset(fdset, 0, fdsetsz); | |
1264 | ||
1265 | for (i = 0; i < num_listen_socks; i++) | |
1266 | FD_SET(listen_socks[i], fdset); | |
1267 | for (i = 0; i < options.max_startups; i++) | |
1268 | if (startup_pipes[i] != -1) | |
1269 | FD_SET(startup_pipes[i], fdset); | |
1270 | ||
1271 | /* Wait in select until there is a connection. */ | |
1272 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); | |
1273 | if (ret < 0 && errno != EINTR) | |
1274 | error("select: %.100s", strerror(errno)); | |
1275 | if (received_sigterm) { | |
70791e56 | 1276 | logit("Received signal %d; terminating.", |
1e608e42 | 1277 | (int) received_sigterm); |
3c0ef626 | 1278 | close_listen_socks(); |
1279 | unlink(options.pid_file); | |
1280 | exit(255); | |
1281 | } | |
1282 | if (key_used && key_do_regen) { | |
1283 | generate_ephemeral_server_key(); | |
1284 | key_used = 0; | |
1285 | key_do_regen = 0; | |
1286 | } | |
1287 | if (ret < 0) | |
1288 | continue; | |
1289 | ||
1290 | for (i = 0; i < options.max_startups; i++) | |
1291 | if (startup_pipes[i] != -1 && | |
1292 | FD_ISSET(startup_pipes[i], fdset)) { | |
1293 | /* | |
1294 | * the read end of the pipe is ready | |
1295 | * if the child has closed the pipe | |
1296 | * after successful authentication | |
1297 | * or if the child has died | |
1298 | */ | |
1299 | close(startup_pipes[i]); | |
1300 | startup_pipes[i] = -1; | |
1301 | startups--; | |
1302 | } | |
1303 | for (i = 0; i < num_listen_socks; i++) { | |
1304 | if (!FD_ISSET(listen_socks[i], fdset)) | |
1305 | continue; | |
1306 | fromlen = sizeof(from); | |
1307 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
1308 | &fromlen); | |
1309 | if (newsock < 0) { | |
1310 | if (errno != EINTR && errno != EWOULDBLOCK) | |
1311 | error("accept: %.100s", strerror(errno)); | |
1312 | continue; | |
1313 | } | |
1314 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
1315 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
1e608e42 | 1316 | close(newsock); |
3c0ef626 | 1317 | continue; |
1318 | } | |
1319 | if (drop_connection(startups) == 1) { | |
1320 | debug("drop connection #%d", startups); | |
1321 | close(newsock); | |
1322 | continue; | |
1323 | } | |
1324 | if (pipe(startup_p) == -1) { | |
1325 | close(newsock); | |
1326 | continue; | |
1327 | } | |
1328 | ||
1329 | for (j = 0; j < options.max_startups; j++) | |
1330 | if (startup_pipes[j] == -1) { | |
1331 | startup_pipes[j] = startup_p[0]; | |
1332 | if (maxfd < startup_p[0]) | |
1333 | maxfd = startup_p[0]; | |
1334 | startups++; | |
1335 | break; | |
1336 | } | |
1337 | ||
1338 | /* | |
1339 | * Got connection. Fork a child to handle it, unless | |
1340 | * we are in debugging mode. | |
1341 | */ | |
1342 | if (debug_flag) { | |
1343 | /* | |
1344 | * In debugging mode. Close the listening | |
1345 | * socket, and start processing the | |
1346 | * connection without forking. | |
1347 | */ | |
1348 | debug("Server will not fork when running in debugging mode."); | |
1349 | close_listen_socks(); | |
1350 | sock_in = newsock; | |
1351 | sock_out = newsock; | |
1352 | startup_pipe = -1; | |
1353 | pid = getpid(); | |
1354 | break; | |
1355 | } else { | |
1356 | /* | |
1357 | * Normal production daemon. Fork, and have | |
1358 | * the child process the connection. The | |
1359 | * parent continues listening. | |
1360 | */ | |
1361 | if ((pid = fork()) == 0) { | |
1362 | /* | |
1363 | * Child. Close the listening and max_startup | |
1364 | * sockets. Start using the accepted socket. | |
1365 | * Reinitialize logging (since our pid has | |
1366 | * changed). We break out of the loop to handle | |
1367 | * the connection. | |
1368 | */ | |
1369 | startup_pipe = startup_p[1]; | |
1e608e42 | 1370 | close_startup_pipes(); |
3c0ef626 | 1371 | close_listen_socks(); |
1372 | sock_in = newsock; | |
1373 | sock_out = newsock; | |
1374 | log_init(__progname, options.log_level, options.log_facility, log_stderr); | |
1375 | break; | |
1376 | } | |
1377 | } | |
1378 | ||
1379 | /* Parent. Stay in the loop. */ | |
1380 | if (pid < 0) | |
1381 | error("fork: %.100s", strerror(errno)); | |
1382 | else | |
ff2d7a98 | 1383 | debug("Forked child %ld.", (long)pid); |
3c0ef626 | 1384 | |
1385 | close(startup_p[1]); | |
1386 | ||
1387 | /* Mark that the key has been used (it was "given" to the child). */ | |
1388 | if ((options.protocol & SSH_PROTO_1) && | |
1389 | key_used == 0) { | |
1390 | /* Schedule server key regeneration alarm. */ | |
1391 | signal(SIGALRM, key_regeneration_alarm); | |
1392 | alarm(options.key_regeneration_time); | |
1393 | key_used = 1; | |
1394 | } | |
1395 | ||
1396 | arc4random_stir(); | |
1397 | ||
1398 | /* Close the new socket (the child is now taking care of it). */ | |
1399 | close(newsock); | |
1400 | } | |
1401 | /* child process check (or debug mode) */ | |
1402 | if (num_listen_socks < 0) | |
1403 | break; | |
1404 | } | |
1405 | } | |
1406 | ||
1407 | /* This is the child processing a new connection. */ | |
1408 | ||
2980ea68 | 1409 | /* |
1410 | * Create a new session and process group since the 4.4BSD | |
1411 | * setlogin() affects the entire process group. We don't | |
1412 | * want the child to be able to affect the parent. | |
1413 | */ | |
70791e56 | 1414 | #if !defined(SSHD_ACQUIRES_CTTY) |
1c14df9e | 1415 | /* |
70791e56 | 1416 | * If setsid is called, on some platforms sshd will later acquire a |
1417 | * controlling terminal which will result in "could not set | |
1418 | * controlling tty" errors. | |
1c14df9e | 1419 | */ |
ff2d7a98 | 1420 | if (!debug_flag && !inetd_flag && setsid() < 0) |
2980ea68 | 1421 | error("setsid: %.100s", strerror(errno)); |
1422 | #endif | |
1423 | ||
3c0ef626 | 1424 | /* |
1425 | * Disable the key regeneration alarm. We will not regenerate the | |
1426 | * key since we are no longer in a position to give it to anyone. We | |
1427 | * will not restart on SIGHUP since it no longer makes sense. | |
1428 | */ | |
1429 | alarm(0); | |
1430 | signal(SIGALRM, SIG_DFL); | |
1431 | signal(SIGHUP, SIG_DFL); | |
1432 | signal(SIGTERM, SIG_DFL); | |
1433 | signal(SIGQUIT, SIG_DFL); | |
1434 | signal(SIGCHLD, SIG_DFL); | |
1435 | signal(SIGINT, SIG_DFL); | |
1436 | ||
416fd2a8 | 1437 | /* Set SO_KEEPALIVE if requested. */ |
1438 | if (options.tcp_keep_alive && | |
1e608e42 | 1439 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, |
3c0ef626 | 1440 | sizeof(on)) < 0) |
1441 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1442 | ||
1443 | /* | |
1444 | * Register our connection. This turns encryption off because we do | |
1445 | * not have a key. | |
1446 | */ | |
1447 | packet_set_connection(sock_in, sock_out); | |
1448 | ||
1449 | remote_port = get_remote_port(); | |
1450 | remote_ip = get_remote_ipaddr(); | |
1451 | ||
1452 | #ifdef LIBWRAP | |
1453 | /* Check whether logins are denied from this host. */ | |
1454 | { | |
1455 | struct request_info req; | |
1456 | ||
1457 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); | |
1458 | fromhost(&req); | |
1459 | ||
1460 | if (!hosts_access(&req)) { | |
1461 | debug("Connection refused by tcp wrapper"); | |
1462 | refuse(&req); | |
1463 | /* NOTREACHED */ | |
1464 | fatal("libwrap refuse returns"); | |
1465 | } | |
1466 | } | |
1467 | #endif /* LIBWRAP */ | |
1468 | ||
1469 | /* Log the connection. */ | |
1470 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
1471 | ||
1472 | /* | |
1473 | * We don\'t want to listen forever unless the other side | |
1474 | * successfully authenticates itself. So we set up an alarm which is | |
1475 | * cleared after successful authentication. A limit of zero | |
1476 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1477 | * mode; it is just annoying to have the server exit just when you | |
1478 | * are about to discover the bug. | |
1479 | */ | |
1480 | signal(SIGALRM, grace_alarm_handler); | |
1481 | if (!debug_flag) | |
1482 | alarm(options.login_grace_time); | |
1483 | ||
1484 | sshd_exchange_identification(sock_in, sock_out); | |
70791e56 | 1485 | #if defined(AFS_KRB5) |
3c0ef626 | 1486 | /* If machine has AFS, set process authentication group. */ |
1487 | if (k_hasafs()) { | |
1488 | k_setpag(); | |
1489 | k_unlog(); | |
1490 | } | |
f2fd21a2 | 1491 | #endif /* AFS || AFS_KRB5 */ |
3c0ef626 | 1492 | |
1493 | packet_set_nonblocking(); | |
1494 | ||
416fd2a8 | 1495 | /* prepare buffers to collect authentication messages */ |
70791e56 | 1496 | buffer_init(&loginmsg); |
1497 | ||
416fd2a8 | 1498 | /* allocate authentication context */ |
1499 | authctxt = xmalloc(sizeof(*authctxt)); | |
1500 | memset(authctxt, 0, sizeof(*authctxt)); | |
1501 | ||
1502 | /* XXX global for cleanup, access from other modules */ | |
1503 | the_authctxt = authctxt; | |
1504 | ||
2980ea68 | 1505 | if (use_privsep) |
416fd2a8 | 1506 | if (privsep_preauth(authctxt) == 1) |
2980ea68 | 1507 | goto authenticated; |
1508 | ||
3c0ef626 | 1509 | /* perform the key exchange */ |
1510 | /* authenticate user and start session */ | |
1511 | if (compat20) { | |
1512 | do_ssh2_kex(); | |
416fd2a8 | 1513 | do_authentication2(authctxt); |
3c0ef626 | 1514 | } else { |
1515 | do_ssh1_kex(); | |
416fd2a8 | 1516 | do_authentication(authctxt); |
2980ea68 | 1517 | } |
1518 | /* | |
1519 | * If we use privilege separation, the unprivileged child transfers | |
1520 | * the current keystate and exits | |
1521 | */ | |
1522 | if (use_privsep) { | |
1523 | mm_send_keystate(pmonitor); | |
1524 | exit(0); | |
3c0ef626 | 1525 | } |
2980ea68 | 1526 | |
1527 | authenticated: | |
1528 | /* | |
1529 | * In privilege separation, we fork another child and prepare | |
1530 | * file descriptor passing. | |
1531 | */ | |
1532 | if (use_privsep) { | |
1533 | privsep_postauth(authctxt); | |
1534 | /* the monitor process [priv] will not return */ | |
1535 | if (!compat20) | |
1536 | destroy_sensitive_data(); | |
1537 | } | |
1538 | ||
416fd2a8 | 1539 | /* Start session. */ |
2980ea68 | 1540 | do_authenticated(authctxt); |
1541 | ||
3c0ef626 | 1542 | /* The connection has been terminated. */ |
1543 | verbose("Closing connection to %.100s", remote_ip); | |
1544 | ||
1545 | #ifdef USE_PAM | |
70791e56 | 1546 | if (options.use_pam) |
1547 | finish_pam(); | |
3c0ef626 | 1548 | #endif /* USE_PAM */ |
1549 | ||
1550 | packet_close(); | |
2980ea68 | 1551 | |
1552 | if (use_privsep) | |
1553 | mm_terminate(); | |
1554 | ||
3c0ef626 | 1555 | exit(0); |
1556 | } | |
1557 | ||
2980ea68 | 1558 | /* |
1559 | * Decrypt session_key_int using our private server key and private host key | |
1560 | * (key with larger modulus first). | |
1561 | */ | |
1562 | int | |
1563 | ssh1_session_key(BIGNUM *session_key_int) | |
1564 | { | |
1565 | int rsafail = 0; | |
1566 | ||
1567 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { | |
1568 | /* Server key has bigger modulus. */ | |
1569 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < | |
1570 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1571 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1572 | get_remote_ipaddr(), | |
1573 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1574 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1575 | SSH_KEY_BITS_RESERVED); | |
1576 | } | |
1577 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1578 | sensitive_data.server_key->rsa) <= 0) | |
1579 | rsafail++; | |
1580 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1581 | sensitive_data.ssh1_host_key->rsa) <= 0) | |
1582 | rsafail++; | |
1583 | } else { | |
1584 | /* Host key has bigger modulus (or they are equal). */ | |
1585 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < | |
1586 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1587 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1588 | get_remote_ipaddr(), | |
1589 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1590 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1591 | SSH_KEY_BITS_RESERVED); | |
1592 | } | |
1593 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1594 | sensitive_data.ssh1_host_key->rsa) < 0) | |
1595 | rsafail++; | |
1596 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1597 | sensitive_data.server_key->rsa) < 0) | |
1598 | rsafail++; | |
1599 | } | |
1600 | return (rsafail); | |
1601 | } | |
3c0ef626 | 1602 | /* |
1603 | * SSH1 key exchange | |
1604 | */ | |
1605 | static void | |
1606 | do_ssh1_kex(void) | |
1607 | { | |
1608 | int i, len; | |
3c0ef626 | 1609 | int rsafail = 0; |
1610 | BIGNUM *session_key_int; | |
1611 | u_char session_key[SSH_SESSION_KEY_LENGTH]; | |
1612 | u_char cookie[8]; | |
1613 | u_int cipher_type, auth_mask, protocol_flags; | |
e54b3d7c | 1614 | u_int32_t rnd = 0; |
3c0ef626 | 1615 | |
1616 | /* | |
1617 | * Generate check bytes that the client must send back in the user | |
1618 | * packet in order for it to be accepted; this is used to defy ip | |
1619 | * spoofing attacks. Note that this only works against somebody | |
1620 | * doing IP spoofing from a remote machine; any machine on the local | |
1621 | * network can still see outgoing packets and catch the random | |
1622 | * cookie. This only affects rhosts authentication, and this is one | |
1623 | * of the reasons why it is inherently insecure. | |
1624 | */ | |
1625 | for (i = 0; i < 8; i++) { | |
1626 | if (i % 4 == 0) | |
e54b3d7c | 1627 | rnd = arc4random(); |
1628 | cookie[i] = rnd & 0xff; | |
1629 | rnd >>= 8; | |
3c0ef626 | 1630 | } |
1631 | ||
1632 | /* | |
1633 | * Send our public key. We include in the packet 64 bits of random | |
1634 | * data that must be matched in the reply in order to prevent IP | |
1635 | * spoofing. | |
1636 | */ | |
1637 | packet_start(SSH_SMSG_PUBLIC_KEY); | |
1638 | for (i = 0; i < 8; i++) | |
1639 | packet_put_char(cookie[i]); | |
1640 | ||
1641 | /* Store our public server RSA key. */ | |
1642 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); | |
1643 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1644 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
1645 | ||
1646 | /* Store our public host RSA key. */ | |
1647 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
1648 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1649 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
1650 | ||
1651 | /* Put protocol flags. */ | |
1652 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1653 | ||
1654 | /* Declare which ciphers we support. */ | |
1655 | packet_put_int(cipher_mask_ssh1(0)); | |
1656 | ||
1657 | /* Declare supported authentication types. */ | |
1658 | auth_mask = 0; | |
3c0ef626 | 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; | |
ff2d7a98 | 1663 | if (options.challenge_response_authentication == 1) |
1664 | auth_mask |= 1 << SSH_AUTH_TIS; | |
3c0ef626 | 1665 | if (options.password_authentication) |
1666 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1667 | packet_put_int(auth_mask); | |
1668 | ||
1669 | /* Send the packet and wait for it to be sent. */ | |
1670 | packet_send(); | |
1671 | packet_write_wait(); | |
1672 | ||
1673 | debug("Sent %d bit server key and %d bit host key.", | |
1674 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1675 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
1676 | ||
1677 | /* Read clients reply (cipher type and session key). */ | |
1e608e42 | 1678 | packet_read_expect(SSH_CMSG_SESSION_KEY); |
3c0ef626 | 1679 | |
1680 | /* Get cipher type and check whether we accept this. */ | |
1681 | cipher_type = packet_get_char(); | |
1682 | ||
1683 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) | |
1684 | packet_disconnect("Warning: client selects unsupported cipher."); | |
1685 | ||
1686 | /* Get check bytes from the packet. These must match those we | |
1687 | sent earlier with the public key packet. */ | |
1688 | for (i = 0; i < 8; i++) | |
1689 | if (cookie[i] != packet_get_char()) | |
1690 | packet_disconnect("IP Spoofing check bytes do not match."); | |
1691 | ||
1692 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1693 | ||
1694 | /* Get the encrypted integer. */ | |
1e608e42 | 1695 | if ((session_key_int = BN_new()) == NULL) |
1696 | fatal("do_ssh1_kex: BN_new failed"); | |
1697 | packet_get_bignum(session_key_int); | |
3c0ef626 | 1698 | |
1699 | protocol_flags = packet_get_int(); | |
1700 | packet_set_protocol_flags(protocol_flags); | |
1e608e42 | 1701 | packet_check_eom(); |
3c0ef626 | 1702 | |
2980ea68 | 1703 | /* Decrypt session_key_int using host/server keys */ |
1704 | rsafail = PRIVSEP(ssh1_session_key(session_key_int)); | |
1705 | ||
3c0ef626 | 1706 | /* |
1707 | * Extract session key from the decrypted integer. The key is in the | |
1708 | * least significant 256 bits of the integer; the first byte of the | |
1709 | * key is in the highest bits. | |
1710 | */ | |
1711 | if (!rsafail) { | |
1712 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
1713 | len = BN_num_bytes(session_key_int); | |
1714 | if (len < 0 || len > sizeof(session_key)) { | |
1715 | error("do_connection: bad session key len from %s: " | |
1716 | "session_key_int %d > sizeof(session_key) %lu", | |
1717 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); | |
1718 | rsafail++; | |
1719 | } else { | |
1720 | memset(session_key, 0, sizeof(session_key)); | |
1721 | BN_bn2bin(session_key_int, | |
1722 | session_key + sizeof(session_key) - len); | |
1723 | ||
1724 | compute_session_id(session_id, cookie, | |
1725 | sensitive_data.ssh1_host_key->rsa->n, | |
1726 | sensitive_data.server_key->rsa->n); | |
1727 | /* | |
1728 | * Xor the first 16 bytes of the session key with the | |
1729 | * session id. | |
1730 | */ | |
1731 | for (i = 0; i < 16; i++) | |
1732 | session_key[i] ^= session_id[i]; | |
1733 | } | |
1734 | } | |
1735 | if (rsafail) { | |
1736 | int bytes = BN_num_bytes(session_key_int); | |
1e608e42 | 1737 | u_char *buf = xmalloc(bytes); |
3c0ef626 | 1738 | MD5_CTX md; |
1739 | ||
70791e56 | 1740 | logit("do_connection: generating a fake encryption key"); |
3c0ef626 | 1741 | BN_bn2bin(session_key_int, buf); |
1742 | MD5_Init(&md); | |
1743 | MD5_Update(&md, buf, bytes); | |
1744 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1745 | MD5_Final(session_key, &md); | |
1746 | MD5_Init(&md); | |
1747 | MD5_Update(&md, session_key, 16); | |
1748 | MD5_Update(&md, buf, bytes); | |
1749 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1750 | MD5_Final(session_key + 16, &md); | |
1751 | memset(buf, 0, bytes); | |
1752 | xfree(buf); | |
1753 | for (i = 0; i < 16; i++) | |
1754 | session_id[i] = session_key[i] ^ session_key[i + 16]; | |
1755 | } | |
2980ea68 | 1756 | /* Destroy the private and public keys. No longer. */ |
3c0ef626 | 1757 | destroy_sensitive_data(); |
1758 | ||
2980ea68 | 1759 | if (use_privsep) |
1760 | mm_ssh1_session_id(session_id); | |
1761 | ||
3c0ef626 | 1762 | /* Destroy the decrypted integer. It is no longer needed. */ |
1763 | BN_clear_free(session_key_int); | |
1764 | ||
1765 | /* Set the session key. From this on all communications will be encrypted. */ | |
1766 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1767 | ||
1768 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1769 | memset(session_key, 0, sizeof(session_key)); | |
1770 | ||
1771 | debug("Received session key; encryption turned on."); | |
1772 | ||
ff2d7a98 | 1773 | /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ |
3c0ef626 | 1774 | packet_start(SSH_SMSG_SUCCESS); |
1775 | packet_send(); | |
1776 | packet_write_wait(); | |
1777 | } | |
1778 | ||
1779 | /* | |
1780 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1781 | */ | |
1782 | static void | |
1783 | do_ssh2_kex(void) | |
1784 | { | |
1785 | Kex *kex; | |
1786 | ||
1787 | if (options.ciphers != NULL) { | |
1788 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
1789 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; | |
1790 | } | |
1791 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = | |
1792 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); | |
1793 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
1794 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); | |
1795 | ||
1796 | if (options.macs != NULL) { | |
1797 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
1798 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
1799 | } | |
ff2d7a98 | 1800 | if (!options.compression) { |
1801 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
1802 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
1803 | } | |
3c0ef626 | 1804 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
1805 | ||
5598e598 | 1806 | #ifdef GSSAPI |
1807 | { | |
1808 | char *orig; | |
1809 | char *gss = NULL; | |
1810 | char *newstr = NULL; | |
1811 | orig = myproposal[PROPOSAL_KEX_ALGS]; | |
1812 | ||
1813 | /* If we don't have a host key, then all of the algorithms | |
1814 | * currently in myproposal are useless */ | |
1815 | if (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])==0) | |
1816 | orig= NULL; | |
1817 | ||
1818 | if (options.gss_keyex) | |
88928908 | 1819 | gss = ssh_gssapi_server_mechanisms(); |
5598e598 | 1820 | else |
1821 | gss = NULL; | |
1822 | ||
1823 | if (gss && orig) { | |
1824 | int len = strlen(orig) + strlen(gss) +2; | |
1825 | newstr=xmalloc(len); | |
1826 | snprintf(newstr,len,"%s,%s",gss,orig); | |
1827 | } else if (gss) { | |
1828 | newstr=gss; | |
1829 | } else if (orig) { | |
1830 | newstr=orig; | |
1831 | } | |
1832 | /* If we've got GSSAPI mechanisms, then we've also got the 'null' | |
1833 | host key algorithm, but we're not allowed to advertise it, unless | |
1834 | its the only host key algorithm we're supporting */ | |
1835 | if (gss && (strlen(myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS])) == 0) { | |
1836 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS]="null"; | |
1837 | } | |
1838 | if (newstr) | |
1839 | myproposal[PROPOSAL_KEX_ALGS]=newstr; | |
1840 | else | |
1841 | fatal("No supported key exchange algorithms"); | |
1842 | } | |
1843 | #endif | |
1844 | ||
3c0ef626 | 1845 | /* start key exchange */ |
1846 | kex = kex_setup(myproposal); | |
1c14df9e | 1847 | kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; |
1848 | kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; | |
1849 | #ifdef GSSAPI | |
1850 | kex->kex[KEX_GSS_GRP1_SHA1] = kexgss_server; | |
1851 | #endif | |
3c0ef626 | 1852 | kex->server = 1; |
1853 | kex->client_version_string=client_version_string; | |
1854 | kex->server_version_string=server_version_string; | |
1855 | kex->load_host_key=&get_hostkey_by_type; | |
2980ea68 | 1856 | kex->host_key_index=&get_hostkey_index; |
3c0ef626 | 1857 | |
1858 | xxx_kex = kex; | |
1859 | ||
1860 | dispatch_run(DISPATCH_BLOCK, &kex->done, kex); | |
1861 | ||
1862 | session_id2 = kex->session_id; | |
1863 | session_id2_len = kex->session_id_len; | |
1864 | ||
1865 | #ifdef DEBUG_KEXDH | |
1866 | /* send 1st encrypted/maced/compressed message */ | |
1867 | packet_start(SSH2_MSG_IGNORE); | |
1868 | packet_put_cstring("markus"); | |
1869 | packet_send(); | |
1870 | packet_write_wait(); | |
1871 | #endif | |
1872 | debug("KEX done"); | |
1873 | } | |
416fd2a8 | 1874 | |
1875 | /* server specific fatal cleanup */ | |
1876 | void | |
1877 | cleanup_exit(int i) | |
1878 | { | |
1879 | if (the_authctxt) | |
1880 | do_cleanup(the_authctxt); | |
1881 | _exit(i); | |
1882 | } |