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8efc0c15 | 1 | /* |
5260325f | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
bcbf86ec | 5 | * This program is the ssh daemon. It listens for connections from clients, |
6 | * and performs authentication, executes use commands or shell, and forwards | |
5260325f | 7 | * information to/from the application to the user client over an encrypted |
bcbf86ec | 8 | * connection. This can also handle forwarding of X11, TCP/IP, and |
9 | * authentication agent connections. | |
e78a59f5 | 10 | * |
bcbf86ec | 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: | |
1853d1ef | 18 | * Privilege Separation: |
bcbf86ec | 19 | * |
1853d1ef | 20 | * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved. |
21 | * Copyright (c) 2002 Niels Provos. All rights reserved. | |
bcbf86ec | 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. | |
5260325f | 42 | */ |
8efc0c15 | 43 | |
44 | #include "includes.h" | |
dc54438a | 45 | RCSID("$OpenBSD: sshd.c,v 1.271 2003/06/28 16:23:06 deraadt Exp $"); |
8efc0c15 | 46 | |
42f11eb2 | 47 | #include <openssl/dh.h> |
48 | #include <openssl/bn.h> | |
436c347c | 49 | #include <openssl/md5.h> |
1853d1ef | 50 | #include <openssl/rand.h> |
6e879cb4 | 51 | #ifdef HAVE_SECUREWARE |
52 | #include <sys/security.h> | |
53 | #include <prot.h> | |
54 | #endif | |
42f11eb2 | 55 | |
56 | #include "ssh.h" | |
57 | #include "ssh1.h" | |
58 | #include "ssh2.h" | |
8efc0c15 | 59 | #include "xmalloc.h" |
60 | #include "rsa.h" | |
1729c161 | 61 | #include "sshpty.h" |
8efc0c15 | 62 | #include "packet.h" |
8efc0c15 | 63 | #include "mpaux.h" |
42f11eb2 | 64 | #include "log.h" |
8efc0c15 | 65 | #include "servconf.h" |
66 | #include "uidswap.h" | |
67 | #include "compat.h" | |
7368a6c8 | 68 | #include "buffer.h" |
42f11eb2 | 69 | #include "cipher.h" |
e78a59f5 | 70 | #include "kex.h" |
7368a6c8 | 71 | #include "key.h" |
94ec8c6b | 72 | #include "dh.h" |
e78a59f5 | 73 | #include "myproposal.h" |
a306f2dd | 74 | #include "authfile.h" |
42f11eb2 | 75 | #include "pathnames.h" |
76 | #include "atomicio.h" | |
77 | #include "canohost.h" | |
78 | #include "auth.h" | |
79 | #include "misc.h" | |
a5c9ffdb | 80 | #include "dispatch.h" |
e4d7f734 | 81 | #include "channels.h" |
1b34c1b3 | 82 | #include "session.h" |
1853d1ef | 83 | #include "monitor_mm.h" |
84 | #include "monitor.h" | |
85 | #include "monitor_wrap.h" | |
86 | #include "monitor_fdpass.h" | |
8efc0c15 | 87 | |
88 | #ifdef LIBWRAP | |
89 | #include <tcpd.h> | |
90 | #include <syslog.h> | |
91 | int allow_severity = LOG_INFO; | |
92 | int deny_severity = LOG_WARNING; | |
93 | #endif /* LIBWRAP */ | |
94 | ||
95 | #ifndef O_NOCTTY | |
96 | #define O_NOCTTY 0 | |
97 | #endif | |
98 | ||
260d427b | 99 | #ifdef HAVE___PROGNAME |
100 | extern char *__progname; | |
101 | #else | |
102 | char *__progname; | |
103 | #endif | |
104 | ||
8efc0c15 | 105 | /* Server configuration options. */ |
106 | ServerOptions options; | |
107 | ||
108 | /* Name of the server configuration file. */ | |
42f11eb2 | 109 | char *config_file_name = _PATH_SERVER_CONFIG_FILE; |
8efc0c15 | 110 | |
6ae2364d | 111 | /* |
48e671d5 | 112 | * Flag indicating whether IPv4 or IPv6. This can be set on the command line. |
113 | * Default value is AF_UNSPEC means both IPv4 and IPv6. | |
114 | */ | |
115 | int IPv4or6 = AF_UNSPEC; | |
116 | ||
5260325f | 117 | /* |
118 | * Debug mode flag. This can be set on the command line. If debug | |
119 | * mode is enabled, extra debugging output will be sent to the system | |
120 | * log, the daemon will not go to background, and will exit after processing | |
121 | * the first connection. | |
122 | */ | |
8efc0c15 | 123 | int debug_flag = 0; |
124 | ||
f87f09aa | 125 | /* Flag indicating that the daemon should only test the configuration and keys. */ |
126 | int test_flag = 0; | |
127 | ||
8efc0c15 | 128 | /* Flag indicating that the daemon is being started from inetd. */ |
129 | int inetd_flag = 0; | |
130 | ||
0b6fbf03 | 131 | /* Flag indicating that sshd should not detach and become a daemon. */ |
132 | int no_daemon_flag = 0; | |
133 | ||
6a17f9c2 | 134 | /* debug goes to stderr unless inetd_flag is set */ |
135 | int log_stderr = 0; | |
136 | ||
8efc0c15 | 137 | /* Saved arguments to main(). */ |
138 | char **saved_argv; | |
4d33e531 | 139 | int saved_argc; |
8efc0c15 | 140 | |
aa3378df | 141 | /* |
48e671d5 | 142 | * The sockets that the server is listening; this is used in the SIGHUP |
143 | * signal handler. | |
aa3378df | 144 | */ |
48e671d5 | 145 | #define MAX_LISTEN_SOCKS 16 |
146 | int listen_socks[MAX_LISTEN_SOCKS]; | |
147 | int num_listen_socks = 0; | |
8efc0c15 | 148 | |
aa3378df | 149 | /* |
150 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
151 | * sshd will skip the version-number exchange | |
152 | */ | |
5260325f | 153 | char *client_version_string = NULL; |
7368a6c8 | 154 | char *server_version_string = NULL; |
8efc0c15 | 155 | |
7a37c112 | 156 | /* for rekeying XXX fixme */ |
157 | Kex *xxx_kex; | |
158 | ||
aa3378df | 159 | /* |
160 | * Any really sensitive data in the application is contained in this | |
161 | * structure. The idea is that this structure could be locked into memory so | |
162 | * that the pages do not get written into swap. However, there are some | |
163 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
164 | * have access to the internals of them, and locking just the structure is | |
165 | * not very useful. Currently, memory locking is not implemented. | |
166 | */ | |
5260325f | 167 | struct { |
cb7bd922 | 168 | Key *server_key; /* ephemeral server key */ |
fa08c86b | 169 | Key *ssh1_host_key; /* ssh1 host key */ |
170 | Key **host_keys; /* all private host keys */ | |
171 | int have_ssh1_key; | |
172 | int have_ssh2_key; | |
00be5382 | 173 | u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; |
8efc0c15 | 174 | } sensitive_data; |
175 | ||
aa3378df | 176 | /* |
59c97189 | 177 | * Flag indicating whether the RSA server key needs to be regenerated. |
178 | * Is set in the SIGALRM handler and cleared when the key is regenerated. | |
aa3378df | 179 | */ |
7a934d1b | 180 | static volatile sig_atomic_t key_do_regen = 0; |
8efc0c15 | 181 | |
c9130033 | 182 | /* This is set to true when a signal is received. */ |
7a934d1b | 183 | static volatile sig_atomic_t received_sighup = 0; |
184 | static volatile sig_atomic_t received_sigterm = 0; | |
8efc0c15 | 185 | |
7368a6c8 | 186 | /* session identifier, used by RSA-auth */ |
1e3b8b07 | 187 | u_char session_id[16]; |
e7c0f9d5 | 188 | |
a306f2dd | 189 | /* same for ssh2 */ |
1e3b8b07 | 190 | u_char *session_id2 = NULL; |
a27002e5 | 191 | u_int session_id2_len = 0; |
a306f2dd | 192 | |
c345cf9d | 193 | /* record remote hostname or ip */ |
1e3b8b07 | 194 | u_int utmp_len = MAXHOSTNAMELEN; |
c345cf9d | 195 | |
7ace8c3b | 196 | /* options.max_startup sized array of fd ints */ |
197 | int *startup_pipes = NULL; | |
198 | int startup_pipe; /* in child */ | |
199 | ||
1853d1ef | 200 | /* variables used for privilege separation */ |
98a58eda | 201 | int use_privsep; |
202 | struct monitor *pmonitor; | |
1853d1ef | 203 | |
bc7dfc06 | 204 | /* message to be displayed after login */ |
205 | Buffer loginmsg; | |
206 | ||
7368a6c8 | 207 | /* Prototypes for various functions defined later in this file. */ |
396c147e | 208 | void destroy_sensitive_data(void); |
1853d1ef | 209 | void demote_sensitive_data(void); |
c8d54615 | 210 | |
396c147e | 211 | static void do_ssh1_kex(void); |
212 | static void do_ssh2_kex(void); | |
94ec8c6b | 213 | |
48e671d5 | 214 | /* |
215 | * Close all listening sockets | |
216 | */ | |
396c147e | 217 | static void |
48e671d5 | 218 | close_listen_socks(void) |
219 | { | |
220 | int i; | |
e424e241 | 221 | |
48e671d5 | 222 | for (i = 0; i < num_listen_socks; i++) |
223 | close(listen_socks[i]); | |
224 | num_listen_socks = -1; | |
225 | } | |
226 | ||
7ace8c3b | 227 | static void |
228 | close_startup_pipes(void) | |
229 | { | |
230 | int i; | |
e424e241 | 231 | |
7ace8c3b | 232 | if (startup_pipes) |
233 | for (i = 0; i < options.max_startups; i++) | |
234 | if (startup_pipes[i] != -1) | |
235 | close(startup_pipes[i]); | |
236 | } | |
237 | ||
5260325f | 238 | /* |
239 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
240 | * the effect is to reread the configuration file (and to regenerate | |
241 | * the server key). | |
242 | */ | |
396c147e | 243 | static void |
5260325f | 244 | sighup_handler(int sig) |
8efc0c15 | 245 | { |
6056eb35 | 246 | int save_errno = errno; |
247 | ||
5260325f | 248 | received_sighup = 1; |
249 | signal(SIGHUP, sighup_handler); | |
6056eb35 | 250 | errno = save_errno; |
8efc0c15 | 251 | } |
252 | ||
5260325f | 253 | /* |
254 | * Called from the main program after receiving SIGHUP. | |
255 | * Restarts the server. | |
256 | */ | |
396c147e | 257 | static void |
5ca51e19 | 258 | sighup_restart(void) |
8efc0c15 | 259 | { |
bbe88b6d | 260 | logit("Received SIGHUP; restarting."); |
48e671d5 | 261 | close_listen_socks(); |
7ace8c3b | 262 | close_startup_pipes(); |
5260325f | 263 | execv(saved_argv[0], saved_argv); |
bbe88b6d | 264 | logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], |
e424e241 | 265 | strerror(errno)); |
5260325f | 266 | exit(1); |
8efc0c15 | 267 | } |
268 | ||
5260325f | 269 | /* |
270 | * Generic signal handler for terminating signals in the master daemon. | |
5260325f | 271 | */ |
396c147e | 272 | static void |
5260325f | 273 | sigterm_handler(int sig) |
8efc0c15 | 274 | { |
c9130033 | 275 | received_sigterm = sig; |
8efc0c15 | 276 | } |
277 | ||
5260325f | 278 | /* |
279 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
c9130033 | 280 | * reap any zombies left by exited children. |
5260325f | 281 | */ |
396c147e | 282 | static void |
5260325f | 283 | main_sigchld_handler(int sig) |
8efc0c15 | 284 | { |
5260325f | 285 | int save_errno = errno; |
e424e241 | 286 | pid_t pid; |
5260325f | 287 | int status; |
5ad13cd7 | 288 | |
8c38e88b | 289 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || |
290 | (pid < 0 && errno == EINTR)) | |
5260325f | 291 | ; |
5ad13cd7 | 292 | |
5260325f | 293 | signal(SIGCHLD, main_sigchld_handler); |
294 | errno = save_errno; | |
8efc0c15 | 295 | } |
296 | ||
5260325f | 297 | /* |
298 | * Signal handler for the alarm after the login grace period has expired. | |
299 | */ | |
396c147e | 300 | static void |
5260325f | 301 | grace_alarm_handler(int sig) |
8efc0c15 | 302 | { |
c9130033 | 303 | /* XXX no idea how fix this signal handler */ |
304 | ||
5260325f | 305 | /* Log error and exit. */ |
26b9a3d2 | 306 | fatal("Timeout before authentication for %s", get_remote_ipaddr()); |
5260325f | 307 | } |
8efc0c15 | 308 | |
5260325f | 309 | /* |
310 | * Signal handler for the key regeneration alarm. Note that this | |
311 | * alarm only occurs in the daemon waiting for connections, and it does not | |
312 | * do anything with the private key or random state before forking. | |
313 | * Thus there should be no concurrency control/asynchronous execution | |
314 | * problems. | |
315 | */ | |
396c147e | 316 | static void |
cb7bd922 | 317 | generate_ephemeral_server_key(void) |
fa08c86b | 318 | { |
7fdc56c5 | 319 | u_int32_t rnd = 0; |
00be5382 | 320 | int i; |
321 | ||
cd332296 | 322 | verbose("Generating %s%d bit RSA key.", |
76ca7b01 | 323 | sensitive_data.server_key ? "new " : "", options.server_key_bits); |
fa08c86b | 324 | if (sensitive_data.server_key != NULL) |
325 | key_free(sensitive_data.server_key); | |
cd332296 | 326 | sensitive_data.server_key = key_generate(KEY_RSA1, |
76ca7b01 | 327 | options.server_key_bits); |
328 | verbose("RSA key generation complete."); | |
00be5382 | 329 | |
330 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
331 | if (i % 4 == 0) | |
7fdc56c5 | 332 | rnd = arc4random(); |
333 | sensitive_data.ssh1_cookie[i] = rnd & 0xff; | |
334 | rnd >>= 8; | |
00be5382 | 335 | } |
336 | arc4random_stir(); | |
fa08c86b | 337 | } |
f546c780 | 338 | |
396c147e | 339 | static void |
5260325f | 340 | key_regeneration_alarm(int sig) |
341 | { | |
342 | int save_errno = errno; | |
e424e241 | 343 | |
59c97189 | 344 | signal(SIGALRM, SIG_DFL); |
5260325f | 345 | errno = save_errno; |
59c97189 | 346 | key_do_regen = 1; |
5260325f | 347 | } |
8efc0c15 | 348 | |
396c147e | 349 | static void |
7368a6c8 | 350 | sshd_exchange_identification(int sock_in, int sock_out) |
351 | { | |
a8be9f80 | 352 | int i, mismatch; |
7368a6c8 | 353 | int remote_major, remote_minor; |
a8be9f80 | 354 | int major, minor; |
7368a6c8 | 355 | char *s; |
356 | char buf[256]; /* Must not be larger than remote_version. */ | |
357 | char remote_version[256]; /* Must be at least as big as buf. */ | |
358 | ||
a8be9f80 | 359 | if ((options.protocol & SSH_PROTO_1) && |
360 | (options.protocol & SSH_PROTO_2)) { | |
361 | major = PROTOCOL_MAJOR_1; | |
362 | minor = 99; | |
363 | } else if (options.protocol & SSH_PROTO_2) { | |
364 | major = PROTOCOL_MAJOR_2; | |
365 | minor = PROTOCOL_MINOR_2; | |
366 | } else { | |
367 | major = PROTOCOL_MAJOR_1; | |
368 | minor = PROTOCOL_MINOR_1; | |
369 | } | |
370 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
7368a6c8 | 371 | server_version_string = xstrdup(buf); |
372 | ||
373 | if (client_version_string == NULL) { | |
374 | /* Send our protocol version identification. */ | |
dc54438a | 375 | if (atomicio(vwrite, sock_out, server_version_string, |
d6133f43 | 376 | strlen(server_version_string)) |
7368a6c8 | 377 | != strlen(server_version_string)) { |
bbe88b6d | 378 | logit("Could not write ident string to %s", get_remote_ipaddr()); |
7368a6c8 | 379 | fatal_cleanup(); |
380 | } | |
381 | ||
c242fc96 | 382 | /* Read other sides version identification. */ |
cd332296 | 383 | memset(buf, 0, sizeof(buf)); |
7368a6c8 | 384 | for (i = 0; i < sizeof(buf) - 1; i++) { |
e5a0294f | 385 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { |
bbe88b6d | 386 | logit("Did not receive identification string from %s", |
c2b544a5 | 387 | get_remote_ipaddr()); |
7368a6c8 | 388 | fatal_cleanup(); |
389 | } | |
390 | if (buf[i] == '\r') { | |
8a169574 | 391 | buf[i] = 0; |
94ec8c6b | 392 | /* Kludge for F-Secure Macintosh < 1.0.2 */ |
393 | if (i == 12 && | |
394 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
395 | break; | |
7368a6c8 | 396 | continue; |
7368a6c8 | 397 | } |
398 | if (buf[i] == '\n') { | |
8a169574 | 399 | buf[i] = 0; |
7368a6c8 | 400 | break; |
401 | } | |
402 | } | |
403 | buf[sizeof(buf) - 1] = 0; | |
404 | client_version_string = xstrdup(buf); | |
405 | } | |
406 | ||
407 | /* | |
408 | * Check that the versions match. In future this might accept | |
409 | * several versions and set appropriate flags to handle them. | |
410 | */ | |
411 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
412 | &remote_major, &remote_minor, remote_version) != 3) { | |
6ae2364d | 413 | s = "Protocol mismatch.\n"; |
dc54438a | 414 | (void) atomicio(vwrite, sock_out, s, strlen(s)); |
7368a6c8 | 415 | close(sock_in); |
416 | close(sock_out); | |
bbe88b6d | 417 | logit("Bad protocol version identification '%.100s' from %s", |
7368a6c8 | 418 | client_version_string, get_remote_ipaddr()); |
419 | fatal_cleanup(); | |
420 | } | |
421 | debug("Client protocol version %d.%d; client software version %.100s", | |
184eed6a | 422 | remote_major, remote_minor, remote_version); |
7368a6c8 | 423 | |
e78a59f5 | 424 | compat_datafellows(remote_version); |
425 | ||
9a87e2ac | 426 | if (datafellows & SSH_BUG_PROBE) { |
bbe88b6d | 427 | logit("probed from %s with %s. Don't panic.", |
9a87e2ac | 428 | get_remote_ipaddr(), client_version_string); |
429 | fatal_cleanup(); | |
430 | } | |
431 | ||
3a1c54d4 | 432 | if (datafellows & SSH_BUG_SCANNER) { |
bbe88b6d | 433 | logit("scanned from %s with %s. Don't panic.", |
3a1c54d4 | 434 | get_remote_ipaddr(), client_version_string); |
435 | fatal_cleanup(); | |
436 | } | |
437 | ||
a8be9f80 | 438 | mismatch = 0; |
6aacefa7 | 439 | switch (remote_major) { |
7368a6c8 | 440 | case 1: |
a306f2dd | 441 | if (remote_minor == 99) { |
442 | if (options.protocol & SSH_PROTO_2) | |
443 | enable_compat20(); | |
444 | else | |
445 | mismatch = 1; | |
446 | break; | |
447 | } | |
a8be9f80 | 448 | if (!(options.protocol & SSH_PROTO_1)) { |
449 | mismatch = 1; | |
450 | break; | |
451 | } | |
7368a6c8 | 452 | if (remote_minor < 3) { |
089fbbd2 | 453 | packet_disconnect("Your ssh version is too old and " |
7368a6c8 | 454 | "is no longer supported. Please install a newer version."); |
455 | } else if (remote_minor == 3) { | |
456 | /* note that this disables agent-forwarding */ | |
457 | enable_compat13(); | |
458 | } | |
a8be9f80 | 459 | break; |
e78a59f5 | 460 | case 2: |
a8be9f80 | 461 | if (options.protocol & SSH_PROTO_2) { |
e78a59f5 | 462 | enable_compat20(); |
463 | break; | |
464 | } | |
465 | /* FALLTHROUGH */ | |
6ae2364d | 466 | default: |
a8be9f80 | 467 | mismatch = 1; |
468 | break; | |
469 | } | |
470 | chop(server_version_string); | |
a8be9f80 | 471 | debug("Local version string %.200s", server_version_string); |
472 | ||
473 | if (mismatch) { | |
7368a6c8 | 474 | s = "Protocol major versions differ.\n"; |
dc54438a | 475 | (void) atomicio(vwrite, sock_out, s, strlen(s)); |
7368a6c8 | 476 | close(sock_in); |
477 | close(sock_out); | |
bbe88b6d | 478 | logit("Protocol major versions differ for %s: %.200s vs. %.200s", |
a8be9f80 | 479 | get_remote_ipaddr(), |
480 | server_version_string, client_version_string); | |
7368a6c8 | 481 | fatal_cleanup(); |
7368a6c8 | 482 | } |
a306f2dd | 483 | } |
484 | ||
fa08c86b | 485 | /* Destroy the host and server keys. They will no longer be needed. */ |
a306f2dd | 486 | void |
487 | destroy_sensitive_data(void) | |
488 | { | |
fa08c86b | 489 | int i; |
490 | ||
491 | if (sensitive_data.server_key) { | |
492 | key_free(sensitive_data.server_key); | |
493 | sensitive_data.server_key = NULL; | |
494 | } | |
184eed6a | 495 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 496 | if (sensitive_data.host_keys[i]) { |
497 | key_free(sensitive_data.host_keys[i]); | |
498 | sensitive_data.host_keys[i] = NULL; | |
499 | } | |
500 | } | |
501 | sensitive_data.ssh1_host_key = NULL; | |
00be5382 | 502 | memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); |
fa08c86b | 503 | } |
fa08c86b | 504 | |
1853d1ef | 505 | /* Demote private to public keys for network child */ |
506 | void | |
507 | demote_sensitive_data(void) | |
508 | { | |
509 | Key *tmp; | |
510 | int i; | |
511 | ||
512 | if (sensitive_data.server_key) { | |
513 | tmp = key_demote(sensitive_data.server_key); | |
514 | key_free(sensitive_data.server_key); | |
515 | sensitive_data.server_key = tmp; | |
516 | } | |
517 | ||
518 | for (i = 0; i < options.num_host_key_files; i++) { | |
519 | if (sensitive_data.host_keys[i]) { | |
520 | tmp = key_demote(sensitive_data.host_keys[i]); | |
521 | key_free(sensitive_data.host_keys[i]); | |
522 | sensitive_data.host_keys[i] = tmp; | |
523 | if (tmp->type == KEY_RSA1) | |
524 | sensitive_data.ssh1_host_key = tmp; | |
525 | } | |
526 | } | |
527 | ||
528 | /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ | |
529 | } | |
530 | ||
51aeb639 | 531 | static void |
1853d1ef | 532 | privsep_preauth_child(void) |
533 | { | |
7fdc56c5 | 534 | u_int32_t rnd[256]; |
6ded293b | 535 | gid_t gidset[1]; |
2ea6de2b | 536 | struct passwd *pw; |
e424e241 | 537 | int i; |
1853d1ef | 538 | |
539 | /* Enable challenge-response authentication for privilege separation */ | |
540 | privsep_challenge_enable(); | |
541 | ||
542 | for (i = 0; i < 256; i++) | |
7fdc56c5 | 543 | rnd[i] = arc4random(); |
544 | RAND_seed(rnd, sizeof(rnd)); | |
1853d1ef | 545 | |
546 | /* Demote the private keys to public keys. */ | |
547 | demote_sensitive_data(); | |
548 | ||
2ea6de2b | 549 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) |
cdc4fc39 | 550 | fatal("Privilege separation user %s does not exist", |
551 | SSH_PRIVSEP_USER); | |
2ea6de2b | 552 | memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); |
553 | endpwent(); | |
554 | ||
343288b8 | 555 | /* Change our root directory */ |
1c352e97 | 556 | if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) |
557 | fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, | |
558 | strerror(errno)); | |
1853d1ef | 559 | if (chdir("/") == -1) |
edfb66cb | 560 | fatal("chdir(\"/\"): %s", strerror(errno)); |
762715ce | 561 | |
1853d1ef | 562 | /* Drop our privileges */ |
2ea6de2b | 563 | debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, |
564 | (u_int)pw->pw_gid); | |
87809a1f | 565 | #if 0 |
566 | /* XXX not ready, to heavy after chroot */ | |
2ea6de2b | 567 | do_setusercontext(pw); |
87809a1f | 568 | #else |
569 | gidset[0] = pw->pw_gid; | |
87809a1f | 570 | if (setgroups(1, gidset) < 0) |
571 | fatal("setgroups: %.100s", strerror(errno)); | |
572 | permanently_set_uid(pw); | |
573 | #endif | |
1853d1ef | 574 | } |
575 | ||
343288b8 | 576 | static Authctxt * |
324bf712 | 577 | privsep_preauth(void) |
1853d1ef | 578 | { |
324bf712 | 579 | Authctxt *authctxt = NULL; |
1853d1ef | 580 | int status; |
324bf712 | 581 | pid_t pid; |
1853d1ef | 582 | |
324bf712 | 583 | /* Set up unprivileged child process to deal with network data */ |
b5a28cbc | 584 | pmonitor = monitor_init(); |
324bf712 | 585 | /* Store a pointer to the kex for later rekeying */ |
b5a28cbc | 586 | pmonitor->m_pkex = &xxx_kex; |
324bf712 | 587 | |
588 | pid = fork(); | |
589 | if (pid == -1) { | |
590 | fatal("fork of unprivileged child failed"); | |
591 | } else if (pid != 0) { | |
516f0d7d | 592 | fatal_remove_cleanup((void (*) (void *)) packet_close, NULL); |
593 | ||
c457707e | 594 | debug2("Network child is on pid %ld", (long)pid); |
324bf712 | 595 | |
b5a28cbc | 596 | close(pmonitor->m_recvfd); |
597 | authctxt = monitor_child_preauth(pmonitor); | |
598 | close(pmonitor->m_sendfd); | |
324bf712 | 599 | |
600 | /* Sync memory */ | |
b5a28cbc | 601 | monitor_sync(pmonitor); |
324bf712 | 602 | |
603 | /* Wait for the child's exit status */ | |
8c38e88b | 604 | while (waitpid(pid, &status, 0) < 0) |
605 | if (errno != EINTR) | |
606 | break; | |
516f0d7d | 607 | |
608 | /* Reinstall, since the child has finished */ | |
609 | fatal_add_cleanup((void (*) (void *)) packet_close, NULL); | |
610 | ||
324bf712 | 611 | return (authctxt); |
612 | } else { | |
613 | /* child */ | |
614 | ||
b5a28cbc | 615 | close(pmonitor->m_sendfd); |
324bf712 | 616 | |
617 | /* Demote the child */ | |
618 | if (getuid() == 0 || geteuid() == 0) | |
619 | privsep_preauth_child(); | |
47c36e5b | 620 | setproctitle("%s", "[net]"); |
324bf712 | 621 | } |
622 | return (NULL); | |
623 | } | |
624 | ||
625 | static void | |
626 | privsep_postauth(Authctxt *authctxt) | |
627 | { | |
628 | extern Authctxt *x_authctxt; | |
1853d1ef | 629 | |
630 | /* XXX - Remote port forwarding */ | |
631 | x_authctxt = authctxt; | |
632 | ||
94d8258b | 633 | #ifdef DISABLE_FD_PASSING |
d170feb1 | 634 | if (1) { |
635 | #else | |
1853d1ef | 636 | if (authctxt->pw->pw_uid == 0 || options.use_login) { |
d170feb1 | 637 | #endif |
1853d1ef | 638 | /* File descriptor passing is broken or root login */ |
b5a28cbc | 639 | monitor_apply_keystate(pmonitor); |
1853d1ef | 640 | use_privsep = 0; |
641 | return; | |
642 | } | |
762715ce | 643 | |
1853d1ef | 644 | /* Authentication complete */ |
645 | alarm(0); | |
646 | if (startup_pipe != -1) { | |
647 | close(startup_pipe); | |
648 | startup_pipe = -1; | |
649 | } | |
650 | ||
651 | /* New socket pair */ | |
b5a28cbc | 652 | monitor_reinit(pmonitor); |
1853d1ef | 653 | |
b5a28cbc | 654 | pmonitor->m_pid = fork(); |
655 | if (pmonitor->m_pid == -1) | |
1853d1ef | 656 | fatal("fork of unprivileged child failed"); |
b5a28cbc | 657 | else if (pmonitor->m_pid != 0) { |
516f0d7d | 658 | fatal_remove_cleanup((void (*) (void *)) packet_close, NULL); |
659 | ||
c457707e | 660 | debug2("User child is on pid %ld", (long)pmonitor->m_pid); |
b5a28cbc | 661 | close(pmonitor->m_recvfd); |
662 | monitor_child_postauth(pmonitor); | |
1853d1ef | 663 | |
664 | /* NEVERREACHED */ | |
665 | exit(0); | |
666 | } | |
667 | ||
b5a28cbc | 668 | close(pmonitor->m_sendfd); |
1853d1ef | 669 | |
670 | /* Demote the private keys to public keys. */ | |
671 | demote_sensitive_data(); | |
672 | ||
673 | /* Drop privileges */ | |
674 | do_setusercontext(authctxt->pw); | |
675 | ||
676 | /* It is safe now to apply the key state */ | |
b5a28cbc | 677 | monitor_apply_keystate(pmonitor); |
1853d1ef | 678 | } |
679 | ||
396c147e | 680 | static char * |
fa08c86b | 681 | list_hostkey_types(void) |
682 | { | |
3469eac4 | 683 | Buffer b; |
684 | char *p; | |
fa08c86b | 685 | int i; |
3469eac4 | 686 | |
687 | buffer_init(&b); | |
184eed6a | 688 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 689 | Key *key = sensitive_data.host_keys[i]; |
690 | if (key == NULL) | |
691 | continue; | |
6aacefa7 | 692 | switch (key->type) { |
fa08c86b | 693 | case KEY_RSA: |
694 | case KEY_DSA: | |
3469eac4 | 695 | if (buffer_len(&b) > 0) |
696 | buffer_append(&b, ",", 1); | |
697 | p = key_ssh_name(key); | |
698 | buffer_append(&b, p, strlen(p)); | |
fa08c86b | 699 | break; |
700 | } | |
701 | } | |
3469eac4 | 702 | buffer_append(&b, "\0", 1); |
703 | p = xstrdup(buffer_ptr(&b)); | |
704 | buffer_free(&b); | |
705 | debug("list_hostkey_types: %s", p); | |
706 | return p; | |
fa08c86b | 707 | } |
708 | ||
1853d1ef | 709 | Key * |
fa08c86b | 710 | get_hostkey_by_type(int type) |
711 | { | |
712 | int i; | |
e424e241 | 713 | |
184eed6a | 714 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 715 | Key *key = sensitive_data.host_keys[i]; |
716 | if (key != NULL && key->type == type) | |
717 | return key; | |
718 | } | |
719 | return NULL; | |
7368a6c8 | 720 | } |
721 | ||
1853d1ef | 722 | Key * |
723 | get_hostkey_by_index(int ind) | |
724 | { | |
725 | if (ind < 0 || ind >= options.num_host_key_files) | |
726 | return (NULL); | |
727 | return (sensitive_data.host_keys[ind]); | |
728 | } | |
729 | ||
730 | int | |
731 | get_hostkey_index(Key *key) | |
732 | { | |
733 | int i; | |
e424e241 | 734 | |
1853d1ef | 735 | for (i = 0; i < options.num_host_key_files; i++) { |
736 | if (key == sensitive_data.host_keys[i]) | |
737 | return (i); | |
738 | } | |
739 | return (-1); | |
740 | } | |
741 | ||
c345cf9d | 742 | /* |
743 | * returns 1 if connection should be dropped, 0 otherwise. | |
744 | * dropping starts at connection #max_startups_begin with a probability | |
745 | * of (max_startups_rate/100). the probability increases linearly until | |
746 | * all connections are dropped for startups > max_startups | |
747 | */ | |
396c147e | 748 | static int |
c345cf9d | 749 | drop_connection(int startups) |
750 | { | |
751 | double p, r; | |
752 | ||
753 | if (startups < options.max_startups_begin) | |
754 | return 0; | |
755 | if (startups >= options.max_startups) | |
756 | return 1; | |
757 | if (options.max_startups_rate == 100) | |
758 | return 1; | |
759 | ||
760 | p = 100 - options.max_startups_rate; | |
761 | p *= startups - options.max_startups_begin; | |
762 | p /= (double) (options.max_startups - options.max_startups_begin); | |
763 | p += options.max_startups_rate; | |
764 | p /= 100.0; | |
765 | r = arc4random() / (double) UINT_MAX; | |
766 | ||
767 | debug("drop_connection: p %g, r %g", p, r); | |
768 | return (r < p) ? 1 : 0; | |
769 | } | |
770 | ||
2717fa0f | 771 | static void |
772 | usage(void) | |
773 | { | |
774 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
775 | fprintf(stderr, "Usage: %s [options]\n", __progname); | |
776 | fprintf(stderr, "Options:\n"); | |
777 | fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE); | |
778 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); | |
779 | fprintf(stderr, " -i Started from inetd\n"); | |
780 | fprintf(stderr, " -D Do not fork into daemon mode\n"); | |
781 | fprintf(stderr, " -t Only test configuration file and keys\n"); | |
782 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
783 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
784 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
785 | fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n"); | |
786 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
787 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
788 | _PATH_HOST_KEY_FILE); | |
789 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); | |
790 | fprintf(stderr, " -4 Use IPv4 only\n"); | |
791 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
792 | fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n"); | |
793 | exit(1); | |
794 | } | |
795 | ||
5260325f | 796 | /* |
797 | * Main program for the daemon. | |
798 | */ | |
8efc0c15 | 799 | int |
800 | main(int ac, char **av) | |
801 | { | |
5260325f | 802 | extern char *optarg; |
803 | extern int optind; | |
089fbbd2 | 804 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; |
9da5c3c9 | 805 | pid_t pid; |
48e671d5 | 806 | socklen_t fromlen; |
48e671d5 | 807 | fd_set *fdset; |
808 | struct sockaddr_storage from; | |
5260325f | 809 | const char *remote_ip; |
810 | int remote_port; | |
5260325f | 811 | FILE *f; |
48e671d5 | 812 | struct addrinfo *ai; |
813 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
814 | int listen_sock, maxfd; | |
089fbbd2 | 815 | int startup_p[2]; |
816 | int startups = 0; | |
1b34c1b3 | 817 | Authctxt *authctxt; |
aeaa3d9e | 818 | Key *key; |
59c97189 | 819 | int ret, key_used = 0; |
5260325f | 820 | |
6e879cb4 | 821 | #ifdef HAVE_SECUREWARE |
822 | (void)set_auth_parameters(ac, av); | |
823 | #endif | |
260d427b | 824 | __progname = get_progname(av[0]); |
264dce47 | 825 | init_rng(); |
826 | ||
d0104542 | 827 | /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ |
4d33e531 | 828 | saved_argc = ac; |
f420d2ba | 829 | saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1)); |
d0104542 | 830 | for (i = 0; i < ac; i++) |
831 | saved_argv[i] = xstrdup(av[i]); | |
f420d2ba | 832 | saved_argv[i] = NULL; |
d0104542 | 833 | |
834 | #ifndef HAVE_SETPROCTITLE | |
835 | /* Prepare for later setproctitle emulation */ | |
836 | compat_init_setproctitle(ac, av); | |
416c732d | 837 | av = saved_argv; |
d0104542 | 838 | #endif |
5260325f | 839 | |
840 | /* Initialize configuration options to their default values. */ | |
841 | initialize_server_options(&options); | |
842 | ||
843 | /* Parse command-line arguments. */ | |
2717fa0f | 844 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) { |
5260325f | 845 | switch (opt) { |
48e671d5 | 846 | case '4': |
847 | IPv4or6 = AF_INET; | |
848 | break; | |
849 | case '6': | |
850 | IPv4or6 = AF_INET6; | |
851 | break; | |
5260325f | 852 | case 'f': |
853 | config_file_name = optarg; | |
854 | break; | |
855 | case 'd': | |
bcbf86ec | 856 | if (0 == debug_flag) { |
857 | debug_flag = 1; | |
858 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
859 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
860 | options.log_level++; | |
861 | } else { | |
862 | fprintf(stderr, "Too high debugging level.\n"); | |
863 | exit(1); | |
864 | } | |
5260325f | 865 | break; |
0b6fbf03 | 866 | case 'D': |
867 | no_daemon_flag = 1; | |
868 | break; | |
ff14faf1 | 869 | case 'e': |
870 | log_stderr = 1; | |
871 | break; | |
5260325f | 872 | case 'i': |
873 | inetd_flag = 1; | |
874 | break; | |
875 | case 'Q': | |
9bd5b720 | 876 | /* ignored */ |
5260325f | 877 | break; |
878 | case 'q': | |
879 | options.log_level = SYSLOG_LEVEL_QUIET; | |
880 | break; | |
881 | case 'b': | |
882 | options.server_key_bits = atoi(optarg); | |
883 | break; | |
884 | case 'p': | |
48e671d5 | 885 | options.ports_from_cmdline = 1; |
bcbf86ec | 886 | if (options.num_ports >= MAX_PORTS) { |
887 | fprintf(stderr, "too many ports.\n"); | |
888 | exit(1); | |
889 | } | |
2d2a2c65 | 890 | options.ports[options.num_ports++] = a2port(optarg); |
891 | if (options.ports[options.num_ports-1] == 0) { | |
892 | fprintf(stderr, "Bad port number.\n"); | |
893 | exit(1); | |
894 | } | |
5260325f | 895 | break; |
896 | case 'g': | |
e2b1fb42 | 897 | if ((options.login_grace_time = convtime(optarg)) == -1) { |
898 | fprintf(stderr, "Invalid login grace time.\n"); | |
899 | exit(1); | |
900 | } | |
5260325f | 901 | break; |
902 | case 'k': | |
e2b1fb42 | 903 | if ((options.key_regeneration_time = convtime(optarg)) == -1) { |
904 | fprintf(stderr, "Invalid key regeneration interval.\n"); | |
905 | exit(1); | |
906 | } | |
5260325f | 907 | break; |
908 | case 'h': | |
fa08c86b | 909 | if (options.num_host_key_files >= MAX_HOSTKEYS) { |
910 | fprintf(stderr, "too many host keys.\n"); | |
911 | exit(1); | |
912 | } | |
913 | options.host_key_files[options.num_host_key_files++] = optarg; | |
5260325f | 914 | break; |
915 | case 'V': | |
916 | client_version_string = optarg; | |
917 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
918 | inetd_flag = 1; | |
919 | break; | |
f87f09aa | 920 | case 't': |
921 | test_flag = 1; | |
922 | break; | |
c345cf9d | 923 | case 'u': |
924 | utmp_len = atoi(optarg); | |
67f04db1 | 925 | if (utmp_len > MAXHOSTNAMELEN) { |
926 | fprintf(stderr, "Invalid utmp length.\n"); | |
927 | exit(1); | |
928 | } | |
c345cf9d | 929 | break; |
2717fa0f | 930 | case 'o': |
184eed6a | 931 | if (process_server_config_line(&options, optarg, |
2717fa0f | 932 | "command-line", 0) != 0) |
184eed6a | 933 | exit(1); |
2717fa0f | 934 | break; |
5260325f | 935 | case '?': |
936 | default: | |
2717fa0f | 937 | usage(); |
938 | break; | |
5260325f | 939 | } |
940 | } | |
1a92bd7e | 941 | SSLeay_add_all_algorithms(); |
5e4a7219 | 942 | channel_set_af(IPv4or6); |
5260325f | 943 | |
48e671d5 | 944 | /* |
945 | * Force logging to stderr until we have loaded the private host | |
946 | * key (unless started from inetd) | |
947 | */ | |
1fe6a48f | 948 | log_init(__progname, |
980c9344 | 949 | options.log_level == SYSLOG_LEVEL_NOT_SET ? |
950 | SYSLOG_LEVEL_INFO : options.log_level, | |
951 | options.log_facility == SYSLOG_FACILITY_NOT_SET ? | |
952 | SYSLOG_FACILITY_AUTH : options.log_facility, | |
51efad8c | 953 | log_stderr || !inetd_flag); |
48e671d5 | 954 | |
ef51930f | 955 | #ifdef _UNICOS |
1a23ac2c | 956 | /* Cray can define user privs drop all prives now! |
957 | * Not needed on PRIV_SU systems! | |
958 | */ | |
959 | drop_cray_privs(); | |
960 | #endif | |
961 | ||
e339aa53 | 962 | seed_rng(); |
963 | ||
5260325f | 964 | /* Read server configuration options from the configuration file. */ |
965 | read_server_config(&options, config_file_name); | |
966 | ||
967 | /* Fill in default values for those options not explicitly set. */ | |
968 | fill_default_server_options(&options); | |
969 | ||
5260325f | 970 | /* Check that there are no remaining arguments. */ |
971 | if (optind < ac) { | |
972 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
973 | exit(1); | |
8efc0c15 | 974 | } |
5260325f | 975 | |
976 | debug("sshd version %.100s", SSH_VERSION); | |
977 | ||
fa08c86b | 978 | /* load private host keys */ |
343288b8 | 979 | sensitive_data.host_keys = xmalloc(options.num_host_key_files * |
980 | sizeof(Key *)); | |
184eed6a | 981 | for (i = 0; i < options.num_host_key_files; i++) |
1e3b8b07 | 982 | sensitive_data.host_keys[i] = NULL; |
fa08c86b | 983 | sensitive_data.server_key = NULL; |
984 | sensitive_data.ssh1_host_key = NULL; | |
985 | sensitive_data.have_ssh1_key = 0; | |
986 | sensitive_data.have_ssh2_key = 0; | |
a306f2dd | 987 | |
184eed6a | 988 | for (i = 0; i < options.num_host_key_files; i++) { |
aeaa3d9e | 989 | key = key_load_private(options.host_key_files[i], "", NULL); |
990 | sensitive_data.host_keys[i] = key; | |
fa08c86b | 991 | if (key == NULL) { |
58cfa257 | 992 | error("Could not load host key: %s", |
993 | options.host_key_files[i]); | |
aeaa3d9e | 994 | sensitive_data.host_keys[i] = NULL; |
fa08c86b | 995 | continue; |
a306f2dd | 996 | } |
6aacefa7 | 997 | switch (key->type) { |
fa08c86b | 998 | case KEY_RSA1: |
999 | sensitive_data.ssh1_host_key = key; | |
1000 | sensitive_data.have_ssh1_key = 1; | |
1001 | break; | |
1002 | case KEY_RSA: | |
1003 | case KEY_DSA: | |
1004 | sensitive_data.have_ssh2_key = 1; | |
1005 | break; | |
a306f2dd | 1006 | } |
aeaa3d9e | 1007 | debug("private host key: #%d type %d %s", i, key->type, |
1008 | key_type(key)); | |
fa08c86b | 1009 | } |
1010 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
bbe88b6d | 1011 | logit("Disabling protocol version 1. Could not load host key"); |
fa08c86b | 1012 | options.protocol &= ~SSH_PROTO_1; |
1013 | } | |
1014 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
bbe88b6d | 1015 | logit("Disabling protocol version 2. Could not load host key"); |
fa08c86b | 1016 | options.protocol &= ~SSH_PROTO_2; |
a306f2dd | 1017 | } |
6a416424 | 1018 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { |
bbe88b6d | 1019 | logit("sshd: no hostkeys available -- exiting."); |
5260325f | 1020 | exit(1); |
1021 | } | |
5260325f | 1022 | |
a306f2dd | 1023 | /* Check certain values for sanity. */ |
1024 | if (options.protocol & SSH_PROTO_1) { | |
1025 | if (options.server_key_bits < 512 || | |
1026 | options.server_key_bits > 32768) { | |
1027 | fprintf(stderr, "Bad server key size.\n"); | |
1028 | exit(1); | |
1029 | } | |
1030 | /* | |
1031 | * Check that server and host key lengths differ sufficiently. This | |
1032 | * is necessary to make double encryption work with rsaref. Oh, I | |
1033 | * hate software patents. I dont know if this can go? Niels | |
1034 | */ | |
1035 | if (options.server_key_bits > | |
e424e241 | 1036 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - |
1037 | SSH_KEY_BITS_RESERVED && options.server_key_bits < | |
1038 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1039 | SSH_KEY_BITS_RESERVED) { | |
a306f2dd | 1040 | options.server_key_bits = |
e424e241 | 1041 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + |
1042 | SSH_KEY_BITS_RESERVED; | |
a306f2dd | 1043 | debug("Forcing server key to %d bits to make it differ from host key.", |
1044 | options.server_key_bits); | |
1045 | } | |
1046 | } | |
1047 | ||
3cc54fbb | 1048 | if (use_privsep) { |
1049 | struct passwd *pw; | |
1050 | struct stat st; | |
1051 | ||
1052 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
1053 | fatal("Privilege separation user %s does not exist", | |
1054 | SSH_PRIVSEP_USER); | |
1055 | if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || | |
1056 | (S_ISDIR(st.st_mode) == 0)) | |
1057 | fatal("Missing privilege separation directory: %s", | |
1058 | _PATH_PRIVSEP_CHROOT_DIR); | |
b9b82dab | 1059 | |
1060 | #ifdef HAVE_CYGWIN | |
1061 | if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && | |
1062 | (st.st_uid != getuid () || | |
1063 | (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) | |
1064 | #else | |
a56313d7 | 1065 | if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) |
b9b82dab | 1066 | #endif |
5f021474 | 1067 | fatal("%s must be owned by root and not group or " |
1068 | "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); | |
3cc54fbb | 1069 | } |
1070 | ||
f87f09aa | 1071 | /* Configuration looks good, so exit if in test mode. */ |
1072 | if (test_flag) | |
1073 | exit(0); | |
1074 | ||
018a5ea3 | 1075 | /* |
1076 | * Clear out any supplemental groups we may have inherited. This | |
1077 | * prevents inadvertent creation of files with bad modes (in the | |
1078 | * portable version at least, it's certainly possible for PAM | |
1079 | * to create a file, and we can't control the code in every | |
1080 | * module which might be used). | |
1081 | */ | |
1082 | if (setgroups(0, NULL) < 0) | |
1083 | debug("setgroups() failed: %.200s", strerror(errno)); | |
1084 | ||
a306f2dd | 1085 | /* Initialize the log (it is reinitialized below in case we forked). */ |
5260325f | 1086 | if (debug_flag && !inetd_flag) |
1087 | log_stderr = 1; | |
1fe6a48f | 1088 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 1089 | |
a306f2dd | 1090 | /* |
1091 | * If not in debugging mode, and not started from inetd, disconnect | |
1092 | * from the controlling terminal, and fork. The original process | |
1093 | * exits. | |
1094 | */ | |
0b6fbf03 | 1095 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { |
8efc0c15 | 1096 | #ifdef TIOCNOTTY |
5260325f | 1097 | int fd; |
8efc0c15 | 1098 | #endif /* TIOCNOTTY */ |
5260325f | 1099 | if (daemon(0, 0) < 0) |
1100 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1101 | ||
1102 | /* Disconnect from the controlling tty. */ | |
8efc0c15 | 1103 | #ifdef TIOCNOTTY |
5ca51e19 | 1104 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); |
5260325f | 1105 | if (fd >= 0) { |
1106 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
1107 | close(fd); | |
1108 | } | |
8efc0c15 | 1109 | #endif /* TIOCNOTTY */ |
8efc0c15 | 1110 | } |
5260325f | 1111 | /* Reinitialize the log (because of the fork above). */ |
1fe6a48f | 1112 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 1113 | |
5260325f | 1114 | /* Initialize the random number generator. */ |
1115 | arc4random_stir(); | |
1116 | ||
1117 | /* Chdir to the root directory so that the current disk can be | |
1118 | unmounted if desired. */ | |
1119 | chdir("/"); | |
184eed6a | 1120 | |
1d3c30db | 1121 | /* ignore SIGPIPE */ |
1122 | signal(SIGPIPE, SIG_IGN); | |
5260325f | 1123 | |
5260325f | 1124 | /* Start listening for a socket, unless started from inetd. */ |
1125 | if (inetd_flag) { | |
ec1f12d3 | 1126 | int s1; |
5260325f | 1127 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ |
ec1f12d3 | 1128 | dup(s1); |
5260325f | 1129 | sock_in = dup(0); |
1130 | sock_out = dup(1); | |
4c8722d9 | 1131 | startup_pipe = -1; |
a306f2dd | 1132 | /* |
1133 | * We intentionally do not close the descriptors 0, 1, and 2 | |
1134 | * as our code for setting the descriptors won\'t work if | |
1135 | * ttyfd happens to be one of those. | |
1136 | */ | |
5260325f | 1137 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); |
fa08c86b | 1138 | if (options.protocol & SSH_PROTO_1) |
cb7bd922 | 1139 | generate_ephemeral_server_key(); |
5260325f | 1140 | } else { |
48e671d5 | 1141 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
1142 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
1143 | continue; | |
1144 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
1145 | fatal("Too many listen sockets. " | |
1146 | "Enlarge MAX_LISTEN_SOCKS"); | |
1147 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
1148 | ntop, sizeof(ntop), strport, sizeof(strport), | |
1149 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
1150 | error("getnameinfo failed"); | |
1151 | continue; | |
1152 | } | |
1153 | /* Create socket for listening. */ | |
3e131a6d | 1154 | listen_sock = socket(ai->ai_family, ai->ai_socktype, |
1155 | ai->ai_protocol); | |
48e671d5 | 1156 | if (listen_sock < 0) { |
1157 | /* kernel may not support ipv6 */ | |
1158 | verbose("socket: %.100s", strerror(errno)); | |
1159 | continue; | |
1160 | } | |
1161 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
1162 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
1163 | close(listen_sock); | |
1164 | continue; | |
1165 | } | |
1166 | /* | |
facfd613 | 1167 | * Set socket options. |
1168 | * Allow local port reuse in TIME_WAIT. | |
48e671d5 | 1169 | */ |
facfd613 | 1170 | if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, |
1171 | &on, sizeof(on)) == -1) | |
1172 | error("setsockopt SO_REUSEADDR: %s", strerror(errno)); | |
48e671d5 | 1173 | |
1174 | debug("Bind to port %s on %s.", strport, ntop); | |
1175 | ||
1176 | /* Bind the socket to the desired port. */ | |
32ced054 | 1177 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { |
1178 | if (!ai->ai_next) | |
1179 | error("Bind to port %s on %s failed: %.200s.", | |
1180 | strport, ntop, strerror(errno)); | |
48e671d5 | 1181 | close(listen_sock); |
1182 | continue; | |
1183 | } | |
1184 | listen_socks[num_listen_socks] = listen_sock; | |
1185 | num_listen_socks++; | |
1186 | ||
1187 | /* Start listening on the port. */ | |
bbe88b6d | 1188 | logit("Server listening on %s port %s.", ntop, strport); |
48e671d5 | 1189 | if (listen(listen_sock, 5) < 0) |
1190 | fatal("listen: %.100s", strerror(errno)); | |
1191 | ||
5260325f | 1192 | } |
48e671d5 | 1193 | freeaddrinfo(options.listen_addrs); |
1194 | ||
1195 | if (!num_listen_socks) | |
1196 | fatal("Cannot bind any address."); | |
1197 | ||
3aca00a3 | 1198 | if (options.protocol & SSH_PROTO_1) |
1199 | generate_ephemeral_server_key(); | |
1200 | ||
1201 | /* | |
1202 | * Arrange to restart on SIGHUP. The handler needs | |
1203 | * listen_sock. | |
1204 | */ | |
1205 | signal(SIGHUP, sighup_handler); | |
1206 | ||
1207 | signal(SIGTERM, sigterm_handler); | |
1208 | signal(SIGQUIT, sigterm_handler); | |
1209 | ||
1210 | /* Arrange SIGCHLD to be caught. */ | |
1211 | signal(SIGCHLD, main_sigchld_handler); | |
1212 | ||
1213 | /* Write out the pid file after the sigterm handler is setup */ | |
5260325f | 1214 | if (!debug_flag) { |
aa3378df | 1215 | /* |
97fb6912 | 1216 | * Record our pid in /var/run/sshd.pid to make it |
1217 | * easier to kill the correct sshd. We don't want to | |
1218 | * do this before the bind above because the bind will | |
aa3378df | 1219 | * fail if there already is a daemon, and this will |
1220 | * overwrite any old pid in the file. | |
1221 | */ | |
3c62e7eb | 1222 | f = fopen(options.pid_file, "wb"); |
71b9ced0 | 1223 | if (f == NULL) { |
1224 | error("Couldn't create pid file \"%s\": %s", | |
1225 | options.pid_file, strerror(errno)); | |
1226 | } else { | |
c457707e | 1227 | fprintf(f, "%ld\n", (long) getpid()); |
5260325f | 1228 | fclose(f); |
1229 | } | |
8efc0c15 | 1230 | } |
5260325f | 1231 | |
48e671d5 | 1232 | /* setup fd set for listen */ |
089fbbd2 | 1233 | fdset = NULL; |
48e671d5 | 1234 | maxfd = 0; |
1235 | for (i = 0; i < num_listen_socks; i++) | |
1236 | if (listen_socks[i] > maxfd) | |
1237 | maxfd = listen_socks[i]; | |
089fbbd2 | 1238 | /* pipes connected to unauthenticated childs */ |
1239 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
1240 | for (i = 0; i < options.max_startups; i++) | |
1241 | startup_pipes[i] = -1; | |
48e671d5 | 1242 | |
aa3378df | 1243 | /* |
1244 | * Stay listening for connections until the system crashes or | |
1245 | * the daemon is killed with a signal. | |
1246 | */ | |
5260325f | 1247 | for (;;) { |
1248 | if (received_sighup) | |
1249 | sighup_restart(); | |
089fbbd2 | 1250 | if (fdset != NULL) |
1251 | xfree(fdset); | |
b5c334cc | 1252 | fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); |
089fbbd2 | 1253 | fdset = (fd_set *)xmalloc(fdsetsz); |
48e671d5 | 1254 | memset(fdset, 0, fdsetsz); |
089fbbd2 | 1255 | |
48e671d5 | 1256 | for (i = 0; i < num_listen_socks; i++) |
1257 | FD_SET(listen_socks[i], fdset); | |
089fbbd2 | 1258 | for (i = 0; i < options.max_startups; i++) |
1259 | if (startup_pipes[i] != -1) | |
1260 | FD_SET(startup_pipes[i], fdset); | |
1261 | ||
1262 | /* Wait in select until there is a connection. */ | |
59c97189 | 1263 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); |
1264 | if (ret < 0 && errno != EINTR) | |
1265 | error("select: %.100s", strerror(errno)); | |
c9130033 | 1266 | if (received_sigterm) { |
bbe88b6d | 1267 | logit("Received signal %d; terminating.", |
010f9726 | 1268 | (int) received_sigterm); |
c9130033 | 1269 | close_listen_socks(); |
1270 | unlink(options.pid_file); | |
1271 | exit(255); | |
1272 | } | |
59c97189 | 1273 | if (key_used && key_do_regen) { |
cb7bd922 | 1274 | generate_ephemeral_server_key(); |
59c97189 | 1275 | key_used = 0; |
1276 | key_do_regen = 0; | |
48e671d5 | 1277 | } |
59c97189 | 1278 | if (ret < 0) |
1279 | continue; | |
1280 | ||
089fbbd2 | 1281 | for (i = 0; i < options.max_startups; i++) |
1282 | if (startup_pipes[i] != -1 && | |
1283 | FD_ISSET(startup_pipes[i], fdset)) { | |
1284 | /* | |
1285 | * the read end of the pipe is ready | |
1286 | * if the child has closed the pipe | |
8abcdba4 | 1287 | * after successful authentication |
089fbbd2 | 1288 | * or if the child has died |
1289 | */ | |
1290 | close(startup_pipes[i]); | |
1291 | startup_pipes[i] = -1; | |
1292 | startups--; | |
1293 | } | |
48e671d5 | 1294 | for (i = 0; i < num_listen_socks; i++) { |
1295 | if (!FD_ISSET(listen_socks[i], fdset)) | |
5260325f | 1296 | continue; |
089fbbd2 | 1297 | fromlen = sizeof(from); |
1298 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
1299 | &fromlen); | |
1300 | if (newsock < 0) { | |
1301 | if (errno != EINTR && errno != EWOULDBLOCK) | |
1302 | error("accept: %.100s", strerror(errno)); | |
1303 | continue; | |
1304 | } | |
1305 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
1306 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
5e8948af | 1307 | close(newsock); |
089fbbd2 | 1308 | continue; |
1309 | } | |
c345cf9d | 1310 | if (drop_connection(startups) == 1) { |
1311 | debug("drop connection #%d", startups); | |
089fbbd2 | 1312 | close(newsock); |
1313 | continue; | |
1314 | } | |
1315 | if (pipe(startup_p) == -1) { | |
1316 | close(newsock); | |
1317 | continue; | |
1318 | } | |
1319 | ||
1320 | for (j = 0; j < options.max_startups; j++) | |
1321 | if (startup_pipes[j] == -1) { | |
1322 | startup_pipes[j] = startup_p[0]; | |
1323 | if (maxfd < startup_p[0]) | |
1324 | maxfd = startup_p[0]; | |
1325 | startups++; | |
1326 | break; | |
1327 | } | |
2b87da3b | 1328 | |
aa3378df | 1329 | /* |
089fbbd2 | 1330 | * Got connection. Fork a child to handle it, unless |
1331 | * we are in debugging mode. | |
aa3378df | 1332 | */ |
089fbbd2 | 1333 | if (debug_flag) { |
aa3378df | 1334 | /* |
089fbbd2 | 1335 | * In debugging mode. Close the listening |
1336 | * socket, and start processing the | |
1337 | * connection without forking. | |
aa3378df | 1338 | */ |
089fbbd2 | 1339 | debug("Server will not fork when running in debugging mode."); |
48e671d5 | 1340 | close_listen_socks(); |
5260325f | 1341 | sock_in = newsock; |
1342 | sock_out = newsock; | |
5540ea9b | 1343 | startup_pipe = -1; |
3f7a7e4a | 1344 | pid = getpid(); |
5260325f | 1345 | break; |
089fbbd2 | 1346 | } else { |
1347 | /* | |
1348 | * Normal production daemon. Fork, and have | |
1349 | * the child process the connection. The | |
1350 | * parent continues listening. | |
1351 | */ | |
1352 | if ((pid = fork()) == 0) { | |
1353 | /* | |
1354 | * Child. Close the listening and max_startup | |
1355 | * sockets. Start using the accepted socket. | |
1356 | * Reinitialize logging (since our pid has | |
1357 | * changed). We break out of the loop to handle | |
1358 | * the connection. | |
1359 | */ | |
1360 | startup_pipe = startup_p[1]; | |
7ace8c3b | 1361 | close_startup_pipes(); |
089fbbd2 | 1362 | close_listen_socks(); |
1363 | sock_in = newsock; | |
1364 | sock_out = newsock; | |
1fe6a48f | 1365 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
089fbbd2 | 1366 | break; |
1367 | } | |
5260325f | 1368 | } |
5260325f | 1369 | |
089fbbd2 | 1370 | /* Parent. Stay in the loop. */ |
1371 | if (pid < 0) | |
1372 | error("fork: %.100s", strerror(errno)); | |
1373 | else | |
c457707e | 1374 | debug("Forked child %ld.", (long)pid); |
5260325f | 1375 | |
089fbbd2 | 1376 | close(startup_p[1]); |
5260325f | 1377 | |
089fbbd2 | 1378 | /* Mark that the key has been used (it was "given" to the child). */ |
59c97189 | 1379 | if ((options.protocol & SSH_PROTO_1) && |
1380 | key_used == 0) { | |
1381 | /* Schedule server key regeneration alarm. */ | |
8d9bb5dd | 1382 | mysignal(SIGALRM, key_regeneration_alarm); |
59c97189 | 1383 | alarm(options.key_regeneration_time); |
1384 | key_used = 1; | |
1385 | } | |
5260325f | 1386 | |
089fbbd2 | 1387 | arc4random_stir(); |
1388 | ||
1389 | /* Close the new socket (the child is now taking care of it). */ | |
1390 | close(newsock); | |
1391 | } | |
48e671d5 | 1392 | /* child process check (or debug mode) */ |
1393 | if (num_listen_socks < 0) | |
1394 | break; | |
5260325f | 1395 | } |
1396 | } | |
8efc0c15 | 1397 | |
5260325f | 1398 | /* This is the child processing a new connection. */ |
1399 | ||
4ac8556b | 1400 | /* |
1401 | * Create a new session and process group since the 4.4BSD | |
1402 | * setlogin() affects the entire process group. We don't | |
1403 | * want the child to be able to affect the parent. | |
1404 | */ | |
ad84c479 | 1405 | #if !defined(SSHD_ACQUIRES_CTTY) |
6ecd00f8 | 1406 | /* |
ad84c479 | 1407 | * If setsid is called, on some platforms sshd will later acquire a |
1408 | * controlling terminal which will result in "could not set | |
1409 | * controlling tty" errors. | |
6ecd00f8 | 1410 | */ |
c28876e9 | 1411 | if (!debug_flag && !inetd_flag && setsid() < 0) |
4ac8556b | 1412 | error("setsid: %.100s", strerror(errno)); |
30321a9b | 1413 | #endif |
4ac8556b | 1414 | |
aa3378df | 1415 | /* |
1416 | * Disable the key regeneration alarm. We will not regenerate the | |
1417 | * key since we are no longer in a position to give it to anyone. We | |
1418 | * will not restart on SIGHUP since it no longer makes sense. | |
1419 | */ | |
5260325f | 1420 | alarm(0); |
1421 | signal(SIGALRM, SIG_DFL); | |
1422 | signal(SIGHUP, SIG_DFL); | |
1423 | signal(SIGTERM, SIG_DFL); | |
1424 | signal(SIGQUIT, SIG_DFL); | |
1425 | signal(SIGCHLD, SIG_DFL); | |
9aaf9be4 | 1426 | signal(SIGINT, SIG_DFL); |
5260325f | 1427 | |
b5c334cc | 1428 | /* Set keepalives if requested. */ |
1429 | if (options.keepalives && | |
db518d9b | 1430 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, |
b5c334cc | 1431 | sizeof(on)) < 0) |
1432 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1433 | ||
aa3378df | 1434 | /* |
1435 | * Register our connection. This turns encryption off because we do | |
1436 | * not have a key. | |
1437 | */ | |
5260325f | 1438 | packet_set_connection(sock_in, sock_out); |
1439 | ||
1440 | remote_port = get_remote_port(); | |
1441 | remote_ip = get_remote_ipaddr(); | |
1442 | ||
5260325f | 1443 | #ifdef LIBWRAP |
ac28afd8 | 1444 | /* Check whether logins are denied from this host. */ |
5260325f | 1445 | { |
1446 | struct request_info req; | |
8efc0c15 | 1447 | |
8fbc356d | 1448 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); |
5260325f | 1449 | fromhost(&req); |
8efc0c15 | 1450 | |
5260325f | 1451 | if (!hosts_access(&req)) { |
ac28afd8 | 1452 | debug("Connection refused by tcp wrapper"); |
563834bb | 1453 | refuse(&req); |
ac28afd8 | 1454 | /* NOTREACHED */ |
1455 | fatal("libwrap refuse returns"); | |
5260325f | 1456 | } |
8efc0c15 | 1457 | } |
48e671d5 | 1458 | #endif /* LIBWRAP */ |
ac28afd8 | 1459 | |
5260325f | 1460 | /* Log the connection. */ |
1461 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
8efc0c15 | 1462 | |
aa3378df | 1463 | /* |
1464 | * We don\'t want to listen forever unless the other side | |
1465 | * successfully authenticates itself. So we set up an alarm which is | |
1466 | * cleared after successful authentication. A limit of zero | |
1467 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1468 | * mode; it is just annoying to have the server exit just when you | |
1469 | * are about to discover the bug. | |
1470 | */ | |
8d9bb5dd | 1471 | mysignal(SIGALRM, grace_alarm_handler); |
5260325f | 1472 | if (!debug_flag) |
1473 | alarm(options.login_grace_time); | |
1474 | ||
7368a6c8 | 1475 | sshd_exchange_identification(sock_in, sock_out); |
aa3378df | 1476 | /* |
6ffc9c88 | 1477 | * Check that the connection comes from a privileged port. |
c242fc96 | 1478 | * Rhosts-Authentication only makes sense from privileged |
aa3378df | 1479 | * programs. Of course, if the intruder has root access on his local |
1480 | * machine, he can connect from any port. So do not use these | |
1481 | * authentication methods from machines that you do not trust. | |
1482 | */ | |
44b1a8e5 | 1483 | if (options.rhosts_authentication && |
1484 | (remote_port >= IPPORT_RESERVED || | |
1485 | remote_port < IPPORT_RESERVED / 2)) { | |
6ffc9c88 | 1486 | debug("Rhosts Authentication disabled, " |
9ae3f727 | 1487 | "originating port %d not trusted.", remote_port); |
5260325f | 1488 | options.rhosts_authentication = 0; |
5260325f | 1489 | } |
ced49be2 | 1490 | #if defined(KRB4) && !defined(KRB5) |
48e671d5 | 1491 | if (!packet_connection_is_ipv4() && |
1492 | options.kerberos_authentication) { | |
1493 | debug("Kerberos Authentication disabled, only available for IPv4."); | |
1494 | options.kerberos_authentication = 0; | |
1495 | } | |
ced49be2 | 1496 | #endif /* KRB4 && !KRB5 */ |
abf1f107 | 1497 | #ifdef AFS |
1498 | /* If machine has AFS, set process authentication group. */ | |
1499 | if (k_hasafs()) { | |
1500 | k_setpag(); | |
1501 | k_unlog(); | |
1502 | } | |
1503 | #endif /* AFS */ | |
48e671d5 | 1504 | |
5260325f | 1505 | packet_set_nonblocking(); |
1506 | ||
bc7dfc06 | 1507 | /* prepare buffers to collect authentication messages */ |
1508 | buffer_init(&loginmsg); | |
1509 | ||
324bf712 | 1510 | if (use_privsep) |
1511 | if ((authctxt = privsep_preauth()) != NULL) | |
1512 | goto authenticated; | |
1853d1ef | 1513 | |
7b2ea3a1 | 1514 | /* perform the key exchange */ |
7b2ea3a1 | 1515 | /* authenticate user and start session */ |
e78a59f5 | 1516 | if (compat20) { |
1517 | do_ssh2_kex(); | |
1b34c1b3 | 1518 | authctxt = do_authentication2(); |
e78a59f5 | 1519 | } else { |
1520 | do_ssh1_kex(); | |
1b34c1b3 | 1521 | authctxt = do_authentication(); |
e78a59f5 | 1522 | } |
324bf712 | 1523 | /* |
1524 | * If we use privilege separation, the unprivileged child transfers | |
1525 | * the current keystate and exits | |
1526 | */ | |
1527 | if (use_privsep) { | |
b5a28cbc | 1528 | mm_send_keystate(pmonitor); |
1853d1ef | 1529 | exit(0); |
324bf712 | 1530 | } |
1853d1ef | 1531 | |
1532 | authenticated: | |
762715ce | 1533 | /* |
1853d1ef | 1534 | * In privilege separation, we fork another child and prepare |
1535 | * file descriptor passing. | |
1536 | */ | |
1537 | if (use_privsep) { | |
324bf712 | 1538 | privsep_postauth(authctxt); |
1539 | /* the monitor process [priv] will not return */ | |
1853d1ef | 1540 | if (!compat20) |
1541 | destroy_sensitive_data(); | |
1542 | } | |
1b34c1b3 | 1543 | |
1544 | /* Perform session preparation. */ | |
1545 | do_authenticated(authctxt); | |
1546 | ||
63284fbb | 1547 | /* The connection has been terminated. */ |
1548 | verbose("Closing connection to %.100s", remote_ip); | |
8efc0c15 | 1549 | |
d94aa2ae | 1550 | #ifdef USE_PAM |
7fceb20d | 1551 | if (options.use_pam) |
1552 | finish_pam(); | |
d94aa2ae | 1553 | #endif /* USE_PAM */ |
8efc0c15 | 1554 | |
5260325f | 1555 | packet_close(); |
1853d1ef | 1556 | |
1557 | if (use_privsep) | |
1558 | mm_terminate(); | |
1559 | ||
5260325f | 1560 | exit(0); |
1561 | } | |
8efc0c15 | 1562 | |
4f08e98d | 1563 | /* |
1564 | * Decrypt session_key_int using our private server key and private host key | |
1565 | * (key with larger modulus first). | |
1566 | */ | |
1853d1ef | 1567 | int |
4f08e98d | 1568 | ssh1_session_key(BIGNUM *session_key_int) |
1569 | { | |
1570 | int rsafail = 0; | |
1571 | ||
1572 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { | |
1573 | /* Server key has bigger modulus. */ | |
1574 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < | |
1575 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1576 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1577 | get_remote_ipaddr(), | |
1578 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1579 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1580 | SSH_KEY_BITS_RESERVED); | |
1581 | } | |
1582 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1583 | sensitive_data.server_key->rsa) <= 0) | |
1584 | rsafail++; | |
1585 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1586 | sensitive_data.ssh1_host_key->rsa) <= 0) | |
1587 | rsafail++; | |
1588 | } else { | |
1589 | /* Host key has bigger modulus (or they are equal). */ | |
1590 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < | |
1591 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1592 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1593 | get_remote_ipaddr(), | |
1594 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1595 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1596 | SSH_KEY_BITS_RESERVED); | |
1597 | } | |
1598 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1599 | sensitive_data.ssh1_host_key->rsa) < 0) | |
1600 | rsafail++; | |
1601 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1602 | sensitive_data.server_key->rsa) < 0) | |
1603 | rsafail++; | |
1604 | } | |
1605 | return (rsafail); | |
1606 | } | |
5260325f | 1607 | /* |
7b2ea3a1 | 1608 | * SSH1 key exchange |
5260325f | 1609 | */ |
396c147e | 1610 | static void |
1e3b8b07 | 1611 | do_ssh1_kex(void) |
8efc0c15 | 1612 | { |
5260325f | 1613 | int i, len; |
46aa2d1f | 1614 | int rsafail = 0; |
5260325f | 1615 | BIGNUM *session_key_int; |
1e3b8b07 | 1616 | u_char session_key[SSH_SESSION_KEY_LENGTH]; |
1617 | u_char cookie[8]; | |
1618 | u_int cipher_type, auth_mask, protocol_flags; | |
7fdc56c5 | 1619 | u_int32_t rnd = 0; |
5260325f | 1620 | |
aa3378df | 1621 | /* |
1622 | * Generate check bytes that the client must send back in the user | |
1623 | * packet in order for it to be accepted; this is used to defy ip | |
1624 | * spoofing attacks. Note that this only works against somebody | |
1625 | * doing IP spoofing from a remote machine; any machine on the local | |
1626 | * network can still see outgoing packets and catch the random | |
1627 | * cookie. This only affects rhosts authentication, and this is one | |
1628 | * of the reasons why it is inherently insecure. | |
1629 | */ | |
5260325f | 1630 | for (i = 0; i < 8; i++) { |
1631 | if (i % 4 == 0) | |
7fdc56c5 | 1632 | rnd = arc4random(); |
1633 | cookie[i] = rnd & 0xff; | |
1634 | rnd >>= 8; | |
5260325f | 1635 | } |
1636 | ||
aa3378df | 1637 | /* |
1638 | * Send our public key. We include in the packet 64 bits of random | |
1639 | * data that must be matched in the reply in order to prevent IP | |
1640 | * spoofing. | |
1641 | */ | |
5260325f | 1642 | packet_start(SSH_SMSG_PUBLIC_KEY); |
1643 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1644 | packet_put_char(cookie[i]); |
5260325f | 1645 | |
1646 | /* Store our public server RSA key. */ | |
fa08c86b | 1647 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); |
1648 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1649 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
5260325f | 1650 | |
1651 | /* Store our public host RSA key. */ | |
fa08c86b | 1652 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); |
1653 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1654 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
5260325f | 1655 | |
1656 | /* Put protocol flags. */ | |
1657 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1658 | ||
1659 | /* Declare which ciphers we support. */ | |
94ec8c6b | 1660 | packet_put_int(cipher_mask_ssh1(0)); |
5260325f | 1661 | |
1662 | /* Declare supported authentication types. */ | |
1663 | auth_mask = 0; | |
1664 | if (options.rhosts_authentication) | |
1665 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
1666 | if (options.rhosts_rsa_authentication) | |
1667 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1668 | if (options.rsa_authentication) | |
1669 | auth_mask |= 1 << SSH_AUTH_RSA; | |
ced49be2 | 1670 | #if defined(KRB4) || defined(KRB5) |
5260325f | 1671 | if (options.kerberos_authentication) |
1672 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
8efc0c15 | 1673 | #endif |
ced49be2 | 1674 | #if defined(AFS) || defined(KRB5) |
5260325f | 1675 | if (options.kerberos_tgt_passing) |
1676 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
ced49be2 | 1677 | #endif |
1678 | #ifdef AFS | |
5260325f | 1679 | if (options.afs_token_passing) |
1680 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
8efc0c15 | 1681 | #endif |
5ba55ada | 1682 | if (options.challenge_response_authentication == 1) |
5260325f | 1683 | auth_mask |= 1 << SSH_AUTH_TIS; |
5260325f | 1684 | if (options.password_authentication) |
1685 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1686 | packet_put_int(auth_mask); | |
1687 | ||
1688 | /* Send the packet and wait for it to be sent. */ | |
1689 | packet_send(); | |
1690 | packet_write_wait(); | |
1691 | ||
fa08c86b | 1692 | debug("Sent %d bit server key and %d bit host key.", |
1693 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1694 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
5260325f | 1695 | |
1696 | /* Read clients reply (cipher type and session key). */ | |
54a5250f | 1697 | packet_read_expect(SSH_CMSG_SESSION_KEY); |
5260325f | 1698 | |
2d86a6cc | 1699 | /* Get cipher type and check whether we accept this. */ |
5260325f | 1700 | cipher_type = packet_get_char(); |
1701 | ||
94ec8c6b | 1702 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) |
2d86a6cc | 1703 | packet_disconnect("Warning: client selects unsupported cipher."); |
1704 | ||
5260325f | 1705 | /* Get check bytes from the packet. These must match those we |
1706 | sent earlier with the public key packet. */ | |
1707 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1708 | if (cookie[i] != packet_get_char()) |
5260325f | 1709 | packet_disconnect("IP Spoofing check bytes do not match."); |
1710 | ||
1711 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1712 | ||
1713 | /* Get the encrypted integer. */ | |
b775c6f2 | 1714 | if ((session_key_int = BN_new()) == NULL) |
1715 | fatal("do_ssh1_kex: BN_new failed"); | |
20b279e6 | 1716 | packet_get_bignum(session_key_int); |
5260325f | 1717 | |
5260325f | 1718 | protocol_flags = packet_get_int(); |
1719 | packet_set_protocol_flags(protocol_flags); | |
95500969 | 1720 | packet_check_eom(); |
5260325f | 1721 | |
4f08e98d | 1722 | /* Decrypt session_key_int using host/server keys */ |
1853d1ef | 1723 | rsafail = PRIVSEP(ssh1_session_key(session_key_int)); |
1724 | ||
aa3378df | 1725 | /* |
1726 | * Extract session key from the decrypted integer. The key is in the | |
1727 | * least significant 256 bits of the integer; the first byte of the | |
1728 | * key is in the highest bits. | |
1729 | */ | |
46aa2d1f | 1730 | if (!rsafail) { |
1731 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
1732 | len = BN_num_bytes(session_key_int); | |
1733 | if (len < 0 || len > sizeof(session_key)) { | |
1734 | error("do_connection: bad session key len from %s: " | |
5ca51e19 | 1735 | "session_key_int %d > sizeof(session_key) %lu", |
1736 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); | |
46aa2d1f | 1737 | rsafail++; |
1738 | } else { | |
1739 | memset(session_key, 0, sizeof(session_key)); | |
1740 | BN_bn2bin(session_key_int, | |
1741 | session_key + sizeof(session_key) - len); | |
00be5382 | 1742 | |
1743 | compute_session_id(session_id, cookie, | |
1744 | sensitive_data.ssh1_host_key->rsa->n, | |
1745 | sensitive_data.server_key->rsa->n); | |
1746 | /* | |
1747 | * Xor the first 16 bytes of the session key with the | |
1748 | * session id. | |
1749 | */ | |
1750 | for (i = 0; i < 16; i++) | |
1751 | session_key[i] ^= session_id[i]; | |
46aa2d1f | 1752 | } |
1753 | } | |
1754 | if (rsafail) { | |
00be5382 | 1755 | int bytes = BN_num_bytes(session_key_int); |
f6b1ba8f | 1756 | u_char *buf = xmalloc(bytes); |
00be5382 | 1757 | MD5_CTX md; |
1758 | ||
bbe88b6d | 1759 | logit("do_connection: generating a fake encryption key"); |
00be5382 | 1760 | BN_bn2bin(session_key_int, buf); |
1761 | MD5_Init(&md); | |
1762 | MD5_Update(&md, buf, bytes); | |
1763 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1764 | MD5_Final(session_key, &md); | |
1765 | MD5_Init(&md); | |
1766 | MD5_Update(&md, session_key, 16); | |
1767 | MD5_Update(&md, buf, bytes); | |
1768 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1769 | MD5_Final(session_key + 16, &md); | |
1770 | memset(buf, 0, bytes); | |
1771 | xfree(buf); | |
0572fe75 | 1772 | for (i = 0; i < 16; i++) |
1773 | session_id[i] = session_key[i] ^ session_key[i + 16]; | |
46aa2d1f | 1774 | } |
1853d1ef | 1775 | /* Destroy the private and public keys. No longer. */ |
63284fbb | 1776 | destroy_sensitive_data(); |
00be5382 | 1777 | |
1853d1ef | 1778 | if (use_privsep) |
1779 | mm_ssh1_session_id(session_id); | |
1780 | ||
7b2ea3a1 | 1781 | /* Destroy the decrypted integer. It is no longer needed. */ |
1782 | BN_clear_free(session_key_int); | |
1783 | ||
5260325f | 1784 | /* Set the session key. From this on all communications will be encrypted. */ |
1785 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1786 | ||
1787 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1788 | memset(session_key, 0, sizeof(session_key)); | |
1789 | ||
1790 | debug("Received session key; encryption turned on."); | |
1791 | ||
c242fc96 | 1792 | /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ |
5260325f | 1793 | packet_start(SSH_SMSG_SUCCESS); |
1794 | packet_send(); | |
1795 | packet_write_wait(); | |
5260325f | 1796 | } |
e78a59f5 | 1797 | |
1798 | /* | |
1799 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1800 | */ | |
396c147e | 1801 | static void |
1e3b8b07 | 1802 | do_ssh2_kex(void) |
e78a59f5 | 1803 | { |
e78a59f5 | 1804 | Kex *kex; |
e78a59f5 | 1805 | |
a8be9f80 | 1806 | if (options.ciphers != NULL) { |
6ae2364d | 1807 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
a8be9f80 | 1808 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
1809 | } | |
1ad64a93 | 1810 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
1811 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); | |
1812 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
1813 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); | |
1814 | ||
b2552997 | 1815 | if (options.macs != NULL) { |
1816 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
1817 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
1818 | } | |
636f76ca | 1819 | if (!options.compression) { |
1820 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
1821 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
1822 | } | |
fa08c86b | 1823 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
1824 | ||
7a37c112 | 1825 | /* start key exchange */ |
d8ee838b | 1826 | kex = kex_setup(myproposal); |
98a58eda | 1827 | kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; |
1828 | kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; | |
a5c9ffdb | 1829 | kex->server = 1; |
1830 | kex->client_version_string=client_version_string; | |
1831 | kex->server_version_string=server_version_string; | |
1832 | kex->load_host_key=&get_hostkey_by_type; | |
1853d1ef | 1833 | kex->host_key_index=&get_hostkey_index; |
94ec8c6b | 1834 | |
7a37c112 | 1835 | xxx_kex = kex; |
1836 | ||
c422989b | 1837 | dispatch_run(DISPATCH_BLOCK, &kex->done, kex); |
94ec8c6b | 1838 | |
d1ac6175 | 1839 | session_id2 = kex->session_id; |
1840 | session_id2_len = kex->session_id_len; | |
1841 | ||
94ec8c6b | 1842 | #ifdef DEBUG_KEXDH |
1843 | /* send 1st encrypted/maced/compressed message */ | |
1844 | packet_start(SSH2_MSG_IGNORE); | |
1845 | packet_put_cstring("markus"); | |
1846 | packet_send(); | |
1847 | packet_write_wait(); | |
1848 | #endif | |
a5c9ffdb | 1849 | debug("KEX done"); |
e78a59f5 | 1850 | } |