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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" | |
fa5120a0 | 45 | RCSID("$OpenBSD: sshd.c,v 1.267 2003/05/29 16:58:45 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; |
a306f2dd | 191 | int session_id2_len = 0; |
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 | |
7368a6c8 | 204 | /* Prototypes for various functions defined later in this file. */ |
396c147e | 205 | void destroy_sensitive_data(void); |
1853d1ef | 206 | void demote_sensitive_data(void); |
c8d54615 | 207 | |
396c147e | 208 | static void do_ssh1_kex(void); |
209 | static void do_ssh2_kex(void); | |
94ec8c6b | 210 | |
48e671d5 | 211 | /* |
212 | * Close all listening sockets | |
213 | */ | |
396c147e | 214 | static void |
48e671d5 | 215 | close_listen_socks(void) |
216 | { | |
217 | int i; | |
e424e241 | 218 | |
48e671d5 | 219 | for (i = 0; i < num_listen_socks; i++) |
220 | close(listen_socks[i]); | |
221 | num_listen_socks = -1; | |
222 | } | |
223 | ||
7ace8c3b | 224 | static void |
225 | close_startup_pipes(void) | |
226 | { | |
227 | int i; | |
e424e241 | 228 | |
7ace8c3b | 229 | if (startup_pipes) |
230 | for (i = 0; i < options.max_startups; i++) | |
231 | if (startup_pipes[i] != -1) | |
232 | close(startup_pipes[i]); | |
233 | } | |
234 | ||
5260325f | 235 | /* |
236 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
237 | * the effect is to reread the configuration file (and to regenerate | |
238 | * the server key). | |
239 | */ | |
396c147e | 240 | static void |
5260325f | 241 | sighup_handler(int sig) |
8efc0c15 | 242 | { |
6056eb35 | 243 | int save_errno = errno; |
244 | ||
5260325f | 245 | received_sighup = 1; |
246 | signal(SIGHUP, sighup_handler); | |
6056eb35 | 247 | errno = save_errno; |
8efc0c15 | 248 | } |
249 | ||
5260325f | 250 | /* |
251 | * Called from the main program after receiving SIGHUP. | |
252 | * Restarts the server. | |
253 | */ | |
396c147e | 254 | static void |
5ca51e19 | 255 | sighup_restart(void) |
8efc0c15 | 256 | { |
bbe88b6d | 257 | logit("Received SIGHUP; restarting."); |
48e671d5 | 258 | close_listen_socks(); |
7ace8c3b | 259 | close_startup_pipes(); |
5260325f | 260 | execv(saved_argv[0], saved_argv); |
bbe88b6d | 261 | logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], |
e424e241 | 262 | strerror(errno)); |
5260325f | 263 | exit(1); |
8efc0c15 | 264 | } |
265 | ||
5260325f | 266 | /* |
267 | * Generic signal handler for terminating signals in the master daemon. | |
5260325f | 268 | */ |
396c147e | 269 | static void |
5260325f | 270 | sigterm_handler(int sig) |
8efc0c15 | 271 | { |
c9130033 | 272 | received_sigterm = sig; |
8efc0c15 | 273 | } |
274 | ||
5260325f | 275 | /* |
276 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
c9130033 | 277 | * reap any zombies left by exited children. |
5260325f | 278 | */ |
396c147e | 279 | static void |
5260325f | 280 | main_sigchld_handler(int sig) |
8efc0c15 | 281 | { |
5260325f | 282 | int save_errno = errno; |
e424e241 | 283 | pid_t pid; |
5260325f | 284 | int status; |
5ad13cd7 | 285 | |
8c38e88b | 286 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || |
287 | (pid < 0 && errno == EINTR)) | |
5260325f | 288 | ; |
5ad13cd7 | 289 | |
5260325f | 290 | signal(SIGCHLD, main_sigchld_handler); |
291 | errno = save_errno; | |
8efc0c15 | 292 | } |
293 | ||
5260325f | 294 | /* |
295 | * Signal handler for the alarm after the login grace period has expired. | |
296 | */ | |
396c147e | 297 | static void |
5260325f | 298 | grace_alarm_handler(int sig) |
8efc0c15 | 299 | { |
c9130033 | 300 | /* XXX no idea how fix this signal handler */ |
301 | ||
5260325f | 302 | /* Log error and exit. */ |
26b9a3d2 | 303 | fatal("Timeout before authentication for %s", get_remote_ipaddr()); |
5260325f | 304 | } |
8efc0c15 | 305 | |
5260325f | 306 | /* |
307 | * Signal handler for the key regeneration alarm. Note that this | |
308 | * alarm only occurs in the daemon waiting for connections, and it does not | |
309 | * do anything with the private key or random state before forking. | |
310 | * Thus there should be no concurrency control/asynchronous execution | |
311 | * problems. | |
312 | */ | |
396c147e | 313 | static void |
cb7bd922 | 314 | generate_ephemeral_server_key(void) |
fa08c86b | 315 | { |
7fdc56c5 | 316 | u_int32_t rnd = 0; |
00be5382 | 317 | int i; |
318 | ||
cd332296 | 319 | verbose("Generating %s%d bit RSA key.", |
76ca7b01 | 320 | sensitive_data.server_key ? "new " : "", options.server_key_bits); |
fa08c86b | 321 | if (sensitive_data.server_key != NULL) |
322 | key_free(sensitive_data.server_key); | |
cd332296 | 323 | sensitive_data.server_key = key_generate(KEY_RSA1, |
76ca7b01 | 324 | options.server_key_bits); |
325 | verbose("RSA key generation complete."); | |
00be5382 | 326 | |
327 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
328 | if (i % 4 == 0) | |
7fdc56c5 | 329 | rnd = arc4random(); |
330 | sensitive_data.ssh1_cookie[i] = rnd & 0xff; | |
331 | rnd >>= 8; | |
00be5382 | 332 | } |
333 | arc4random_stir(); | |
fa08c86b | 334 | } |
f546c780 | 335 | |
396c147e | 336 | static void |
5260325f | 337 | key_regeneration_alarm(int sig) |
338 | { | |
339 | int save_errno = errno; | |
e424e241 | 340 | |
59c97189 | 341 | signal(SIGALRM, SIG_DFL); |
5260325f | 342 | errno = save_errno; |
59c97189 | 343 | key_do_regen = 1; |
5260325f | 344 | } |
8efc0c15 | 345 | |
396c147e | 346 | static void |
7368a6c8 | 347 | sshd_exchange_identification(int sock_in, int sock_out) |
348 | { | |
a8be9f80 | 349 | int i, mismatch; |
7368a6c8 | 350 | int remote_major, remote_minor; |
a8be9f80 | 351 | int major, minor; |
7368a6c8 | 352 | char *s; |
353 | char buf[256]; /* Must not be larger than remote_version. */ | |
354 | char remote_version[256]; /* Must be at least as big as buf. */ | |
355 | ||
a8be9f80 | 356 | if ((options.protocol & SSH_PROTO_1) && |
357 | (options.protocol & SSH_PROTO_2)) { | |
358 | major = PROTOCOL_MAJOR_1; | |
359 | minor = 99; | |
360 | } else if (options.protocol & SSH_PROTO_2) { | |
361 | major = PROTOCOL_MAJOR_2; | |
362 | minor = PROTOCOL_MINOR_2; | |
363 | } else { | |
364 | major = PROTOCOL_MAJOR_1; | |
365 | minor = PROTOCOL_MINOR_1; | |
366 | } | |
367 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
7368a6c8 | 368 | server_version_string = xstrdup(buf); |
369 | ||
370 | if (client_version_string == NULL) { | |
371 | /* Send our protocol version identification. */ | |
d6133f43 | 372 | if (atomicio(write, sock_out, server_version_string, |
373 | strlen(server_version_string)) | |
7368a6c8 | 374 | != strlen(server_version_string)) { |
bbe88b6d | 375 | logit("Could not write ident string to %s", get_remote_ipaddr()); |
7368a6c8 | 376 | fatal_cleanup(); |
377 | } | |
378 | ||
c242fc96 | 379 | /* Read other sides version identification. */ |
cd332296 | 380 | memset(buf, 0, sizeof(buf)); |
7368a6c8 | 381 | for (i = 0; i < sizeof(buf) - 1; i++) { |
e5a0294f | 382 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { |
bbe88b6d | 383 | logit("Did not receive identification string from %s", |
c2b544a5 | 384 | get_remote_ipaddr()); |
7368a6c8 | 385 | fatal_cleanup(); |
386 | } | |
387 | if (buf[i] == '\r') { | |
8a169574 | 388 | buf[i] = 0; |
94ec8c6b | 389 | /* Kludge for F-Secure Macintosh < 1.0.2 */ |
390 | if (i == 12 && | |
391 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
392 | break; | |
7368a6c8 | 393 | continue; |
7368a6c8 | 394 | } |
395 | if (buf[i] == '\n') { | |
8a169574 | 396 | buf[i] = 0; |
7368a6c8 | 397 | break; |
398 | } | |
399 | } | |
400 | buf[sizeof(buf) - 1] = 0; | |
401 | client_version_string = xstrdup(buf); | |
402 | } | |
403 | ||
404 | /* | |
405 | * Check that the versions match. In future this might accept | |
406 | * several versions and set appropriate flags to handle them. | |
407 | */ | |
408 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
409 | &remote_major, &remote_minor, remote_version) != 3) { | |
6ae2364d | 410 | s = "Protocol mismatch.\n"; |
7368a6c8 | 411 | (void) atomicio(write, sock_out, s, strlen(s)); |
412 | close(sock_in); | |
413 | close(sock_out); | |
bbe88b6d | 414 | logit("Bad protocol version identification '%.100s' from %s", |
7368a6c8 | 415 | client_version_string, get_remote_ipaddr()); |
416 | fatal_cleanup(); | |
417 | } | |
418 | debug("Client protocol version %d.%d; client software version %.100s", | |
184eed6a | 419 | remote_major, remote_minor, remote_version); |
7368a6c8 | 420 | |
e78a59f5 | 421 | compat_datafellows(remote_version); |
422 | ||
9a87e2ac | 423 | if (datafellows & SSH_BUG_PROBE) { |
bbe88b6d | 424 | logit("probed from %s with %s. Don't panic.", |
9a87e2ac | 425 | get_remote_ipaddr(), client_version_string); |
426 | fatal_cleanup(); | |
427 | } | |
428 | ||
3a1c54d4 | 429 | if (datafellows & SSH_BUG_SCANNER) { |
bbe88b6d | 430 | logit("scanned from %s with %s. Don't panic.", |
3a1c54d4 | 431 | get_remote_ipaddr(), client_version_string); |
432 | fatal_cleanup(); | |
433 | } | |
434 | ||
a8be9f80 | 435 | mismatch = 0; |
6aacefa7 | 436 | switch (remote_major) { |
7368a6c8 | 437 | case 1: |
a306f2dd | 438 | if (remote_minor == 99) { |
439 | if (options.protocol & SSH_PROTO_2) | |
440 | enable_compat20(); | |
441 | else | |
442 | mismatch = 1; | |
443 | break; | |
444 | } | |
a8be9f80 | 445 | if (!(options.protocol & SSH_PROTO_1)) { |
446 | mismatch = 1; | |
447 | break; | |
448 | } | |
7368a6c8 | 449 | if (remote_minor < 3) { |
089fbbd2 | 450 | packet_disconnect("Your ssh version is too old and " |
7368a6c8 | 451 | "is no longer supported. Please install a newer version."); |
452 | } else if (remote_minor == 3) { | |
453 | /* note that this disables agent-forwarding */ | |
454 | enable_compat13(); | |
455 | } | |
a8be9f80 | 456 | break; |
e78a59f5 | 457 | case 2: |
a8be9f80 | 458 | if (options.protocol & SSH_PROTO_2) { |
e78a59f5 | 459 | enable_compat20(); |
460 | break; | |
461 | } | |
462 | /* FALLTHROUGH */ | |
6ae2364d | 463 | default: |
a8be9f80 | 464 | mismatch = 1; |
465 | break; | |
466 | } | |
467 | chop(server_version_string); | |
a8be9f80 | 468 | debug("Local version string %.200s", server_version_string); |
469 | ||
470 | if (mismatch) { | |
7368a6c8 | 471 | s = "Protocol major versions differ.\n"; |
472 | (void) atomicio(write, sock_out, s, strlen(s)); | |
473 | close(sock_in); | |
474 | close(sock_out); | |
bbe88b6d | 475 | logit("Protocol major versions differ for %s: %.200s vs. %.200s", |
a8be9f80 | 476 | get_remote_ipaddr(), |
477 | server_version_string, client_version_string); | |
7368a6c8 | 478 | fatal_cleanup(); |
7368a6c8 | 479 | } |
a306f2dd | 480 | } |
481 | ||
fa08c86b | 482 | /* Destroy the host and server keys. They will no longer be needed. */ |
a306f2dd | 483 | void |
484 | destroy_sensitive_data(void) | |
485 | { | |
fa08c86b | 486 | int i; |
487 | ||
488 | if (sensitive_data.server_key) { | |
489 | key_free(sensitive_data.server_key); | |
490 | sensitive_data.server_key = NULL; | |
491 | } | |
184eed6a | 492 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 493 | if (sensitive_data.host_keys[i]) { |
494 | key_free(sensitive_data.host_keys[i]); | |
495 | sensitive_data.host_keys[i] = NULL; | |
496 | } | |
497 | } | |
498 | sensitive_data.ssh1_host_key = NULL; | |
00be5382 | 499 | memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); |
fa08c86b | 500 | } |
fa08c86b | 501 | |
1853d1ef | 502 | /* Demote private to public keys for network child */ |
503 | void | |
504 | demote_sensitive_data(void) | |
505 | { | |
506 | Key *tmp; | |
507 | int i; | |
508 | ||
509 | if (sensitive_data.server_key) { | |
510 | tmp = key_demote(sensitive_data.server_key); | |
511 | key_free(sensitive_data.server_key); | |
512 | sensitive_data.server_key = tmp; | |
513 | } | |
514 | ||
515 | for (i = 0; i < options.num_host_key_files; i++) { | |
516 | if (sensitive_data.host_keys[i]) { | |
517 | tmp = key_demote(sensitive_data.host_keys[i]); | |
518 | key_free(sensitive_data.host_keys[i]); | |
519 | sensitive_data.host_keys[i] = tmp; | |
520 | if (tmp->type == KEY_RSA1) | |
521 | sensitive_data.ssh1_host_key = tmp; | |
522 | } | |
523 | } | |
524 | ||
525 | /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ | |
526 | } | |
527 | ||
51aeb639 | 528 | static void |
1853d1ef | 529 | privsep_preauth_child(void) |
530 | { | |
7fdc56c5 | 531 | u_int32_t rnd[256]; |
6ded293b | 532 | gid_t gidset[1]; |
2ea6de2b | 533 | struct passwd *pw; |
e424e241 | 534 | int i; |
1853d1ef | 535 | |
536 | /* Enable challenge-response authentication for privilege separation */ | |
537 | privsep_challenge_enable(); | |
538 | ||
539 | for (i = 0; i < 256; i++) | |
7fdc56c5 | 540 | rnd[i] = arc4random(); |
541 | RAND_seed(rnd, sizeof(rnd)); | |
1853d1ef | 542 | |
543 | /* Demote the private keys to public keys. */ | |
544 | demote_sensitive_data(); | |
545 | ||
2ea6de2b | 546 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) |
cdc4fc39 | 547 | fatal("Privilege separation user %s does not exist", |
548 | SSH_PRIVSEP_USER); | |
2ea6de2b | 549 | memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); |
550 | endpwent(); | |
551 | ||
343288b8 | 552 | /* Change our root directory */ |
1c352e97 | 553 | if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) |
554 | fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, | |
555 | strerror(errno)); | |
1853d1ef | 556 | if (chdir("/") == -1) |
edfb66cb | 557 | fatal("chdir(\"/\"): %s", strerror(errno)); |
762715ce | 558 | |
1853d1ef | 559 | /* Drop our privileges */ |
2ea6de2b | 560 | debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, |
561 | (u_int)pw->pw_gid); | |
87809a1f | 562 | #if 0 |
563 | /* XXX not ready, to heavy after chroot */ | |
2ea6de2b | 564 | do_setusercontext(pw); |
87809a1f | 565 | #else |
566 | gidset[0] = pw->pw_gid; | |
fa5120a0 | 567 | if (setegid(pw->pw_gid) < 0) |
568 | fatal("setegid failed for %u", (u_int)pw->pw_gid); | |
87809a1f | 569 | if (setgid(pw->pw_gid) < 0) |
fa5120a0 | 570 | fatal("setgid failed for %u", (u_int)pw->pw_gid); |
87809a1f | 571 | if (setgroups(1, gidset) < 0) |
572 | fatal("setgroups: %.100s", strerror(errno)); | |
573 | permanently_set_uid(pw); | |
574 | #endif | |
1853d1ef | 575 | } |
576 | ||
343288b8 | 577 | static Authctxt * |
324bf712 | 578 | privsep_preauth(void) |
1853d1ef | 579 | { |
324bf712 | 580 | Authctxt *authctxt = NULL; |
1853d1ef | 581 | int status; |
324bf712 | 582 | pid_t pid; |
1853d1ef | 583 | |
324bf712 | 584 | /* Set up unprivileged child process to deal with network data */ |
b5a28cbc | 585 | pmonitor = monitor_init(); |
324bf712 | 586 | /* Store a pointer to the kex for later rekeying */ |
b5a28cbc | 587 | pmonitor->m_pkex = &xxx_kex; |
324bf712 | 588 | |
589 | pid = fork(); | |
590 | if (pid == -1) { | |
591 | fatal("fork of unprivileged child failed"); | |
592 | } else if (pid != 0) { | |
516f0d7d | 593 | fatal_remove_cleanup((void (*) (void *)) packet_close, NULL); |
594 | ||
c457707e | 595 | debug2("Network child is on pid %ld", (long)pid); |
324bf712 | 596 | |
b5a28cbc | 597 | close(pmonitor->m_recvfd); |
598 | authctxt = monitor_child_preauth(pmonitor); | |
599 | close(pmonitor->m_sendfd); | |
324bf712 | 600 | |
601 | /* Sync memory */ | |
b5a28cbc | 602 | monitor_sync(pmonitor); |
324bf712 | 603 | |
604 | /* Wait for the child's exit status */ | |
8c38e88b | 605 | while (waitpid(pid, &status, 0) < 0) |
606 | if (errno != EINTR) | |
607 | break; | |
516f0d7d | 608 | |
609 | /* Reinstall, since the child has finished */ | |
610 | fatal_add_cleanup((void (*) (void *)) packet_close, NULL); | |
611 | ||
324bf712 | 612 | return (authctxt); |
613 | } else { | |
614 | /* child */ | |
615 | ||
b5a28cbc | 616 | close(pmonitor->m_sendfd); |
324bf712 | 617 | |
618 | /* Demote the child */ | |
619 | if (getuid() == 0 || geteuid() == 0) | |
620 | privsep_preauth_child(); | |
47c36e5b | 621 | setproctitle("%s", "[net]"); |
324bf712 | 622 | } |
623 | return (NULL); | |
624 | } | |
625 | ||
626 | static void | |
627 | privsep_postauth(Authctxt *authctxt) | |
628 | { | |
629 | extern Authctxt *x_authctxt; | |
1853d1ef | 630 | |
631 | /* XXX - Remote port forwarding */ | |
632 | x_authctxt = authctxt; | |
633 | ||
94d8258b | 634 | #ifdef DISABLE_FD_PASSING |
d170feb1 | 635 | if (1) { |
636 | #else | |
1853d1ef | 637 | if (authctxt->pw->pw_uid == 0 || options.use_login) { |
d170feb1 | 638 | #endif |
1853d1ef | 639 | /* File descriptor passing is broken or root login */ |
b5a28cbc | 640 | monitor_apply_keystate(pmonitor); |
1853d1ef | 641 | use_privsep = 0; |
642 | return; | |
643 | } | |
762715ce | 644 | |
1853d1ef | 645 | /* Authentication complete */ |
646 | alarm(0); | |
647 | if (startup_pipe != -1) { | |
648 | close(startup_pipe); | |
649 | startup_pipe = -1; | |
650 | } | |
651 | ||
652 | /* New socket pair */ | |
b5a28cbc | 653 | monitor_reinit(pmonitor); |
1853d1ef | 654 | |
b5a28cbc | 655 | pmonitor->m_pid = fork(); |
656 | if (pmonitor->m_pid == -1) | |
1853d1ef | 657 | fatal("fork of unprivileged child failed"); |
b5a28cbc | 658 | else if (pmonitor->m_pid != 0) { |
516f0d7d | 659 | fatal_remove_cleanup((void (*) (void *)) packet_close, NULL); |
660 | ||
c457707e | 661 | debug2("User child is on pid %ld", (long)pmonitor->m_pid); |
b5a28cbc | 662 | close(pmonitor->m_recvfd); |
663 | monitor_child_postauth(pmonitor); | |
1853d1ef | 664 | |
665 | /* NEVERREACHED */ | |
666 | exit(0); | |
667 | } | |
668 | ||
b5a28cbc | 669 | close(pmonitor->m_sendfd); |
1853d1ef | 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 */ | |
b5a28cbc | 678 | monitor_apply_keystate(pmonitor); |
1853d1ef | 679 | } |
680 | ||
396c147e | 681 | static char * |
fa08c86b | 682 | list_hostkey_types(void) |
683 | { | |
3469eac4 | 684 | Buffer b; |
685 | char *p; | |
fa08c86b | 686 | int i; |
3469eac4 | 687 | |
688 | buffer_init(&b); | |
184eed6a | 689 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 690 | Key *key = sensitive_data.host_keys[i]; |
691 | if (key == NULL) | |
692 | continue; | |
6aacefa7 | 693 | switch (key->type) { |
fa08c86b | 694 | case KEY_RSA: |
695 | case KEY_DSA: | |
3469eac4 | 696 | if (buffer_len(&b) > 0) |
697 | buffer_append(&b, ",", 1); | |
698 | p = key_ssh_name(key); | |
699 | buffer_append(&b, p, strlen(p)); | |
fa08c86b | 700 | break; |
701 | } | |
702 | } | |
3469eac4 | 703 | buffer_append(&b, "\0", 1); |
704 | p = xstrdup(buffer_ptr(&b)); | |
705 | buffer_free(&b); | |
706 | debug("list_hostkey_types: %s", p); | |
707 | return p; | |
fa08c86b | 708 | } |
709 | ||
1853d1ef | 710 | Key * |
fa08c86b | 711 | get_hostkey_by_type(int type) |
712 | { | |
713 | int i; | |
e424e241 | 714 | |
184eed6a | 715 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 716 | Key *key = sensitive_data.host_keys[i]; |
717 | if (key != NULL && key->type == type) | |
718 | return key; | |
719 | } | |
720 | return NULL; | |
7368a6c8 | 721 | } |
722 | ||
1853d1ef | 723 | Key * |
724 | get_hostkey_by_index(int ind) | |
725 | { | |
726 | if (ind < 0 || ind >= options.num_host_key_files) | |
727 | return (NULL); | |
728 | return (sensitive_data.host_keys[ind]); | |
729 | } | |
730 | ||
731 | int | |
732 | get_hostkey_index(Key *key) | |
733 | { | |
734 | int i; | |
e424e241 | 735 | |
1853d1ef | 736 | for (i = 0; i < options.num_host_key_files; i++) { |
737 | if (key == sensitive_data.host_keys[i]) | |
738 | return (i); | |
739 | } | |
740 | return (-1); | |
741 | } | |
742 | ||
c345cf9d | 743 | /* |
744 | * returns 1 if connection should be dropped, 0 otherwise. | |
745 | * dropping starts at connection #max_startups_begin with a probability | |
746 | * of (max_startups_rate/100). the probability increases linearly until | |
747 | * all connections are dropped for startups > max_startups | |
748 | */ | |
396c147e | 749 | static int |
c345cf9d | 750 | drop_connection(int startups) |
751 | { | |
752 | double p, r; | |
753 | ||
754 | if (startups < options.max_startups_begin) | |
755 | return 0; | |
756 | if (startups >= options.max_startups) | |
757 | return 1; | |
758 | if (options.max_startups_rate == 100) | |
759 | return 1; | |
760 | ||
761 | p = 100 - options.max_startups_rate; | |
762 | p *= startups - options.max_startups_begin; | |
763 | p /= (double) (options.max_startups - options.max_startups_begin); | |
764 | p += options.max_startups_rate; | |
765 | p /= 100.0; | |
766 | r = arc4random() / (double) UINT_MAX; | |
767 | ||
768 | debug("drop_connection: p %g, r %g", p, r); | |
769 | return (r < p) ? 1 : 0; | |
770 | } | |
771 | ||
2717fa0f | 772 | static void |
773 | usage(void) | |
774 | { | |
775 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
776 | fprintf(stderr, "Usage: %s [options]\n", __progname); | |
777 | fprintf(stderr, "Options:\n"); | |
778 | fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE); | |
779 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); | |
780 | fprintf(stderr, " -i Started from inetd\n"); | |
781 | fprintf(stderr, " -D Do not fork into daemon mode\n"); | |
782 | fprintf(stderr, " -t Only test configuration file and keys\n"); | |
783 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
784 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
785 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
786 | fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n"); | |
787 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
788 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
789 | _PATH_HOST_KEY_FILE); | |
790 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); | |
791 | fprintf(stderr, " -4 Use IPv4 only\n"); | |
792 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
793 | fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n"); | |
794 | exit(1); | |
795 | } | |
796 | ||
5260325f | 797 | /* |
798 | * Main program for the daemon. | |
799 | */ | |
8efc0c15 | 800 | int |
801 | main(int ac, char **av) | |
802 | { | |
5260325f | 803 | extern char *optarg; |
804 | extern int optind; | |
089fbbd2 | 805 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; |
9da5c3c9 | 806 | pid_t pid; |
48e671d5 | 807 | socklen_t fromlen; |
48e671d5 | 808 | fd_set *fdset; |
809 | struct sockaddr_storage from; | |
5260325f | 810 | const char *remote_ip; |
811 | int remote_port; | |
5260325f | 812 | FILE *f; |
48e671d5 | 813 | struct addrinfo *ai; |
814 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
815 | int listen_sock, maxfd; | |
089fbbd2 | 816 | int startup_p[2]; |
817 | int startups = 0; | |
1b34c1b3 | 818 | Authctxt *authctxt; |
aeaa3d9e | 819 | Key *key; |
59c97189 | 820 | int ret, key_used = 0; |
5260325f | 821 | |
6e879cb4 | 822 | #ifdef HAVE_SECUREWARE |
823 | (void)set_auth_parameters(ac, av); | |
824 | #endif | |
260d427b | 825 | __progname = get_progname(av[0]); |
264dce47 | 826 | init_rng(); |
827 | ||
d0104542 | 828 | /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ |
4d33e531 | 829 | saved_argc = ac; |
f420d2ba | 830 | saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1)); |
d0104542 | 831 | for (i = 0; i < ac; i++) |
832 | saved_argv[i] = xstrdup(av[i]); | |
f420d2ba | 833 | saved_argv[i] = NULL; |
d0104542 | 834 | |
835 | #ifndef HAVE_SETPROCTITLE | |
836 | /* Prepare for later setproctitle emulation */ | |
837 | compat_init_setproctitle(ac, av); | |
416c732d | 838 | av = saved_argv; |
d0104542 | 839 | #endif |
5260325f | 840 | |
841 | /* Initialize configuration options to their default values. */ | |
842 | initialize_server_options(&options); | |
843 | ||
844 | /* Parse command-line arguments. */ | |
2717fa0f | 845 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) { |
5260325f | 846 | switch (opt) { |
48e671d5 | 847 | case '4': |
848 | IPv4or6 = AF_INET; | |
849 | break; | |
850 | case '6': | |
851 | IPv4or6 = AF_INET6; | |
852 | break; | |
5260325f | 853 | case 'f': |
854 | config_file_name = optarg; | |
855 | break; | |
856 | case 'd': | |
bcbf86ec | 857 | if (0 == debug_flag) { |
858 | debug_flag = 1; | |
859 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
860 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
861 | options.log_level++; | |
862 | } else { | |
863 | fprintf(stderr, "Too high debugging level.\n"); | |
864 | exit(1); | |
865 | } | |
5260325f | 866 | break; |
0b6fbf03 | 867 | case 'D': |
868 | no_daemon_flag = 1; | |
869 | break; | |
ff14faf1 | 870 | case 'e': |
871 | log_stderr = 1; | |
872 | break; | |
5260325f | 873 | case 'i': |
874 | inetd_flag = 1; | |
875 | break; | |
876 | case 'Q': | |
9bd5b720 | 877 | /* ignored */ |
5260325f | 878 | break; |
879 | case 'q': | |
880 | options.log_level = SYSLOG_LEVEL_QUIET; | |
881 | break; | |
882 | case 'b': | |
883 | options.server_key_bits = atoi(optarg); | |
884 | break; | |
885 | case 'p': | |
48e671d5 | 886 | options.ports_from_cmdline = 1; |
bcbf86ec | 887 | if (options.num_ports >= MAX_PORTS) { |
888 | fprintf(stderr, "too many ports.\n"); | |
889 | exit(1); | |
890 | } | |
2d2a2c65 | 891 | options.ports[options.num_ports++] = a2port(optarg); |
892 | if (options.ports[options.num_ports-1] == 0) { | |
893 | fprintf(stderr, "Bad port number.\n"); | |
894 | exit(1); | |
895 | } | |
5260325f | 896 | break; |
897 | case 'g': | |
e2b1fb42 | 898 | if ((options.login_grace_time = convtime(optarg)) == -1) { |
899 | fprintf(stderr, "Invalid login grace time.\n"); | |
900 | exit(1); | |
901 | } | |
5260325f | 902 | break; |
903 | case 'k': | |
e2b1fb42 | 904 | if ((options.key_regeneration_time = convtime(optarg)) == -1) { |
905 | fprintf(stderr, "Invalid key regeneration interval.\n"); | |
906 | exit(1); | |
907 | } | |
5260325f | 908 | break; |
909 | case 'h': | |
fa08c86b | 910 | if (options.num_host_key_files >= MAX_HOSTKEYS) { |
911 | fprintf(stderr, "too many host keys.\n"); | |
912 | exit(1); | |
913 | } | |
914 | options.host_key_files[options.num_host_key_files++] = optarg; | |
5260325f | 915 | break; |
916 | case 'V': | |
917 | client_version_string = optarg; | |
918 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
919 | inetd_flag = 1; | |
920 | break; | |
f87f09aa | 921 | case 't': |
922 | test_flag = 1; | |
923 | break; | |
c345cf9d | 924 | case 'u': |
925 | utmp_len = atoi(optarg); | |
67f04db1 | 926 | if (utmp_len > MAXHOSTNAMELEN) { |
927 | fprintf(stderr, "Invalid utmp length.\n"); | |
928 | exit(1); | |
929 | } | |
c345cf9d | 930 | break; |
2717fa0f | 931 | case 'o': |
184eed6a | 932 | if (process_server_config_line(&options, optarg, |
2717fa0f | 933 | "command-line", 0) != 0) |
184eed6a | 934 | exit(1); |
2717fa0f | 935 | break; |
5260325f | 936 | case '?': |
937 | default: | |
2717fa0f | 938 | usage(); |
939 | break; | |
5260325f | 940 | } |
941 | } | |
1a92bd7e | 942 | SSLeay_add_all_algorithms(); |
5e4a7219 | 943 | channel_set_af(IPv4or6); |
5260325f | 944 | |
48e671d5 | 945 | /* |
946 | * Force logging to stderr until we have loaded the private host | |
947 | * key (unless started from inetd) | |
948 | */ | |
1fe6a48f | 949 | log_init(__progname, |
980c9344 | 950 | options.log_level == SYSLOG_LEVEL_NOT_SET ? |
951 | SYSLOG_LEVEL_INFO : options.log_level, | |
952 | options.log_facility == SYSLOG_FACILITY_NOT_SET ? | |
953 | SYSLOG_FACILITY_AUTH : options.log_facility, | |
51efad8c | 954 | log_stderr || !inetd_flag); |
48e671d5 | 955 | |
ef51930f | 956 | #ifdef _UNICOS |
1a23ac2c | 957 | /* Cray can define user privs drop all prives now! |
958 | * Not needed on PRIV_SU systems! | |
959 | */ | |
960 | drop_cray_privs(); | |
961 | #endif | |
962 | ||
e339aa53 | 963 | seed_rng(); |
964 | ||
5260325f | 965 | /* Read server configuration options from the configuration file. */ |
966 | read_server_config(&options, config_file_name); | |
967 | ||
968 | /* Fill in default values for those options not explicitly set. */ | |
969 | fill_default_server_options(&options); | |
970 | ||
5260325f | 971 | /* Check that there are no remaining arguments. */ |
972 | if (optind < ac) { | |
973 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
974 | exit(1); | |
8efc0c15 | 975 | } |
5260325f | 976 | |
977 | debug("sshd version %.100s", SSH_VERSION); | |
978 | ||
fa08c86b | 979 | /* load private host keys */ |
343288b8 | 980 | sensitive_data.host_keys = xmalloc(options.num_host_key_files * |
981 | sizeof(Key *)); | |
184eed6a | 982 | for (i = 0; i < options.num_host_key_files; i++) |
1e3b8b07 | 983 | sensitive_data.host_keys[i] = NULL; |
fa08c86b | 984 | sensitive_data.server_key = NULL; |
985 | sensitive_data.ssh1_host_key = NULL; | |
986 | sensitive_data.have_ssh1_key = 0; | |
987 | sensitive_data.have_ssh2_key = 0; | |
a306f2dd | 988 | |
184eed6a | 989 | for (i = 0; i < options.num_host_key_files; i++) { |
aeaa3d9e | 990 | key = key_load_private(options.host_key_files[i], "", NULL); |
991 | sensitive_data.host_keys[i] = key; | |
fa08c86b | 992 | if (key == NULL) { |
58cfa257 | 993 | error("Could not load host key: %s", |
994 | options.host_key_files[i]); | |
aeaa3d9e | 995 | sensitive_data.host_keys[i] = NULL; |
fa08c86b | 996 | continue; |
a306f2dd | 997 | } |
6aacefa7 | 998 | switch (key->type) { |
fa08c86b | 999 | case KEY_RSA1: |
1000 | sensitive_data.ssh1_host_key = key; | |
1001 | sensitive_data.have_ssh1_key = 1; | |
1002 | break; | |
1003 | case KEY_RSA: | |
1004 | case KEY_DSA: | |
1005 | sensitive_data.have_ssh2_key = 1; | |
1006 | break; | |
a306f2dd | 1007 | } |
aeaa3d9e | 1008 | debug("private host key: #%d type %d %s", i, key->type, |
1009 | key_type(key)); | |
fa08c86b | 1010 | } |
1011 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
bbe88b6d | 1012 | logit("Disabling protocol version 1. Could not load host key"); |
fa08c86b | 1013 | options.protocol &= ~SSH_PROTO_1; |
1014 | } | |
1015 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
bbe88b6d | 1016 | logit("Disabling protocol version 2. Could not load host key"); |
fa08c86b | 1017 | options.protocol &= ~SSH_PROTO_2; |
a306f2dd | 1018 | } |
6a416424 | 1019 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { |
bbe88b6d | 1020 | logit("sshd: no hostkeys available -- exiting."); |
5260325f | 1021 | exit(1); |
1022 | } | |
5260325f | 1023 | |
a306f2dd | 1024 | /* Check certain values for sanity. */ |
1025 | if (options.protocol & SSH_PROTO_1) { | |
1026 | if (options.server_key_bits < 512 || | |
1027 | options.server_key_bits > 32768) { | |
1028 | fprintf(stderr, "Bad server key size.\n"); | |
1029 | exit(1); | |
1030 | } | |
1031 | /* | |
1032 | * Check that server and host key lengths differ sufficiently. This | |
1033 | * is necessary to make double encryption work with rsaref. Oh, I | |
1034 | * hate software patents. I dont know if this can go? Niels | |
1035 | */ | |
1036 | if (options.server_key_bits > | |
e424e241 | 1037 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - |
1038 | SSH_KEY_BITS_RESERVED && options.server_key_bits < | |
1039 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1040 | SSH_KEY_BITS_RESERVED) { | |
a306f2dd | 1041 | options.server_key_bits = |
e424e241 | 1042 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + |
1043 | SSH_KEY_BITS_RESERVED; | |
a306f2dd | 1044 | debug("Forcing server key to %d bits to make it differ from host key.", |
1045 | options.server_key_bits); | |
1046 | } | |
1047 | } | |
1048 | ||
3cc54fbb | 1049 | if (use_privsep) { |
1050 | struct passwd *pw; | |
1051 | struct stat st; | |
1052 | ||
1053 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
1054 | fatal("Privilege separation user %s does not exist", | |
1055 | SSH_PRIVSEP_USER); | |
1056 | if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || | |
1057 | (S_ISDIR(st.st_mode) == 0)) | |
1058 | fatal("Missing privilege separation directory: %s", | |
1059 | _PATH_PRIVSEP_CHROOT_DIR); | |
b9b82dab | 1060 | |
1061 | #ifdef HAVE_CYGWIN | |
1062 | if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && | |
1063 | (st.st_uid != getuid () || | |
1064 | (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) | |
1065 | #else | |
a56313d7 | 1066 | if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) |
b9b82dab | 1067 | #endif |
5f021474 | 1068 | fatal("%s must be owned by root and not group or " |
1069 | "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); | |
3cc54fbb | 1070 | } |
1071 | ||
f87f09aa | 1072 | /* Configuration looks good, so exit if in test mode. */ |
1073 | if (test_flag) | |
1074 | exit(0); | |
1075 | ||
018a5ea3 | 1076 | /* |
1077 | * Clear out any supplemental groups we may have inherited. This | |
1078 | * prevents inadvertent creation of files with bad modes (in the | |
1079 | * portable version at least, it's certainly possible for PAM | |
1080 | * to create a file, and we can't control the code in every | |
1081 | * module which might be used). | |
1082 | */ | |
1083 | if (setgroups(0, NULL) < 0) | |
1084 | debug("setgroups() failed: %.200s", strerror(errno)); | |
1085 | ||
a306f2dd | 1086 | /* Initialize the log (it is reinitialized below in case we forked). */ |
5260325f | 1087 | if (debug_flag && !inetd_flag) |
1088 | log_stderr = 1; | |
1fe6a48f | 1089 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 1090 | |
a306f2dd | 1091 | /* |
1092 | * If not in debugging mode, and not started from inetd, disconnect | |
1093 | * from the controlling terminal, and fork. The original process | |
1094 | * exits. | |
1095 | */ | |
0b6fbf03 | 1096 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { |
8efc0c15 | 1097 | #ifdef TIOCNOTTY |
5260325f | 1098 | int fd; |
8efc0c15 | 1099 | #endif /* TIOCNOTTY */ |
5260325f | 1100 | if (daemon(0, 0) < 0) |
1101 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1102 | ||
1103 | /* Disconnect from the controlling tty. */ | |
8efc0c15 | 1104 | #ifdef TIOCNOTTY |
5ca51e19 | 1105 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); |
5260325f | 1106 | if (fd >= 0) { |
1107 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
1108 | close(fd); | |
1109 | } | |
8efc0c15 | 1110 | #endif /* TIOCNOTTY */ |
8efc0c15 | 1111 | } |
5260325f | 1112 | /* Reinitialize the log (because of the fork above). */ |
1fe6a48f | 1113 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 1114 | |
5260325f | 1115 | /* Initialize the random number generator. */ |
1116 | arc4random_stir(); | |
1117 | ||
1118 | /* Chdir to the root directory so that the current disk can be | |
1119 | unmounted if desired. */ | |
1120 | chdir("/"); | |
184eed6a | 1121 | |
1d3c30db | 1122 | /* ignore SIGPIPE */ |
1123 | signal(SIGPIPE, SIG_IGN); | |
5260325f | 1124 | |
5260325f | 1125 | /* Start listening for a socket, unless started from inetd. */ |
1126 | if (inetd_flag) { | |
ec1f12d3 | 1127 | int s1; |
5260325f | 1128 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ |
ec1f12d3 | 1129 | dup(s1); |
5260325f | 1130 | sock_in = dup(0); |
1131 | sock_out = dup(1); | |
4c8722d9 | 1132 | startup_pipe = -1; |
a306f2dd | 1133 | /* |
1134 | * We intentionally do not close the descriptors 0, 1, and 2 | |
1135 | * as our code for setting the descriptors won\'t work if | |
1136 | * ttyfd happens to be one of those. | |
1137 | */ | |
5260325f | 1138 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); |
fa08c86b | 1139 | if (options.protocol & SSH_PROTO_1) |
cb7bd922 | 1140 | generate_ephemeral_server_key(); |
5260325f | 1141 | } else { |
48e671d5 | 1142 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
1143 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
1144 | continue; | |
1145 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
1146 | fatal("Too many listen sockets. " | |
1147 | "Enlarge MAX_LISTEN_SOCKS"); | |
1148 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
1149 | ntop, sizeof(ntop), strport, sizeof(strport), | |
1150 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
1151 | error("getnameinfo failed"); | |
1152 | continue; | |
1153 | } | |
1154 | /* Create socket for listening. */ | |
3e131a6d | 1155 | listen_sock = socket(ai->ai_family, ai->ai_socktype, |
1156 | ai->ai_protocol); | |
48e671d5 | 1157 | if (listen_sock < 0) { |
1158 | /* kernel may not support ipv6 */ | |
1159 | verbose("socket: %.100s", strerror(errno)); | |
1160 | continue; | |
1161 | } | |
1162 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
1163 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
1164 | close(listen_sock); | |
1165 | continue; | |
1166 | } | |
1167 | /* | |
facfd613 | 1168 | * Set socket options. |
1169 | * Allow local port reuse in TIME_WAIT. | |
48e671d5 | 1170 | */ |
facfd613 | 1171 | if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, |
1172 | &on, sizeof(on)) == -1) | |
1173 | error("setsockopt SO_REUSEADDR: %s", strerror(errno)); | |
48e671d5 | 1174 | |
1175 | debug("Bind to port %s on %s.", strport, ntop); | |
1176 | ||
1177 | /* Bind the socket to the desired port. */ | |
32ced054 | 1178 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { |
1179 | if (!ai->ai_next) | |
1180 | error("Bind to port %s on %s failed: %.200s.", | |
1181 | strport, ntop, strerror(errno)); | |
48e671d5 | 1182 | close(listen_sock); |
1183 | continue; | |
1184 | } | |
1185 | listen_socks[num_listen_socks] = listen_sock; | |
1186 | num_listen_socks++; | |
1187 | ||
1188 | /* Start listening on the port. */ | |
bbe88b6d | 1189 | logit("Server listening on %s port %s.", ntop, strport); |
48e671d5 | 1190 | if (listen(listen_sock, 5) < 0) |
1191 | fatal("listen: %.100s", strerror(errno)); | |
1192 | ||
5260325f | 1193 | } |
48e671d5 | 1194 | freeaddrinfo(options.listen_addrs); |
1195 | ||
1196 | if (!num_listen_socks) | |
1197 | fatal("Cannot bind any address."); | |
1198 | ||
3aca00a3 | 1199 | if (options.protocol & SSH_PROTO_1) |
1200 | generate_ephemeral_server_key(); | |
1201 | ||
1202 | /* | |
1203 | * Arrange to restart on SIGHUP. The handler needs | |
1204 | * listen_sock. | |
1205 | */ | |
1206 | signal(SIGHUP, sighup_handler); | |
1207 | ||
1208 | signal(SIGTERM, sigterm_handler); | |
1209 | signal(SIGQUIT, sigterm_handler); | |
1210 | ||
1211 | /* Arrange SIGCHLD to be caught. */ | |
1212 | signal(SIGCHLD, main_sigchld_handler); | |
1213 | ||
1214 | /* Write out the pid file after the sigterm handler is setup */ | |
5260325f | 1215 | if (!debug_flag) { |
aa3378df | 1216 | /* |
97fb6912 | 1217 | * Record our pid in /var/run/sshd.pid to make it |
1218 | * easier to kill the correct sshd. We don't want to | |
1219 | * do this before the bind above because the bind will | |
aa3378df | 1220 | * fail if there already is a daemon, and this will |
1221 | * overwrite any old pid in the file. | |
1222 | */ | |
3c62e7eb | 1223 | f = fopen(options.pid_file, "wb"); |
5260325f | 1224 | if (f) { |
c457707e | 1225 | fprintf(f, "%ld\n", (long) getpid()); |
5260325f | 1226 | fclose(f); |
1227 | } | |
8efc0c15 | 1228 | } |
5260325f | 1229 | |
48e671d5 | 1230 | /* setup fd set for listen */ |
089fbbd2 | 1231 | fdset = NULL; |
48e671d5 | 1232 | maxfd = 0; |
1233 | for (i = 0; i < num_listen_socks; i++) | |
1234 | if (listen_socks[i] > maxfd) | |
1235 | maxfd = listen_socks[i]; | |
089fbbd2 | 1236 | /* pipes connected to unauthenticated childs */ |
1237 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
1238 | for (i = 0; i < options.max_startups; i++) | |
1239 | startup_pipes[i] = -1; | |
48e671d5 | 1240 | |
aa3378df | 1241 | /* |
1242 | * Stay listening for connections until the system crashes or | |
1243 | * the daemon is killed with a signal. | |
1244 | */ | |
5260325f | 1245 | for (;;) { |
1246 | if (received_sighup) | |
1247 | sighup_restart(); | |
089fbbd2 | 1248 | if (fdset != NULL) |
1249 | xfree(fdset); | |
b5c334cc | 1250 | fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); |
089fbbd2 | 1251 | fdset = (fd_set *)xmalloc(fdsetsz); |
48e671d5 | 1252 | memset(fdset, 0, fdsetsz); |
089fbbd2 | 1253 | |
48e671d5 | 1254 | for (i = 0; i < num_listen_socks; i++) |
1255 | FD_SET(listen_socks[i], fdset); | |
089fbbd2 | 1256 | for (i = 0; i < options.max_startups; i++) |
1257 | if (startup_pipes[i] != -1) | |
1258 | FD_SET(startup_pipes[i], fdset); | |
1259 | ||
1260 | /* Wait in select until there is a connection. */ | |
59c97189 | 1261 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); |
1262 | if (ret < 0 && errno != EINTR) | |
1263 | error("select: %.100s", strerror(errno)); | |
c9130033 | 1264 | if (received_sigterm) { |
bbe88b6d | 1265 | logit("Received signal %d; terminating.", |
010f9726 | 1266 | (int) received_sigterm); |
c9130033 | 1267 | close_listen_socks(); |
1268 | unlink(options.pid_file); | |
1269 | exit(255); | |
1270 | } | |
59c97189 | 1271 | if (key_used && key_do_regen) { |
cb7bd922 | 1272 | generate_ephemeral_server_key(); |
59c97189 | 1273 | key_used = 0; |
1274 | key_do_regen = 0; | |
48e671d5 | 1275 | } |
59c97189 | 1276 | if (ret < 0) |
1277 | continue; | |
1278 | ||
089fbbd2 | 1279 | for (i = 0; i < options.max_startups; i++) |
1280 | if (startup_pipes[i] != -1 && | |
1281 | FD_ISSET(startup_pipes[i], fdset)) { | |
1282 | /* | |
1283 | * the read end of the pipe is ready | |
1284 | * if the child has closed the pipe | |
8abcdba4 | 1285 | * after successful authentication |
089fbbd2 | 1286 | * or if the child has died |
1287 | */ | |
1288 | close(startup_pipes[i]); | |
1289 | startup_pipes[i] = -1; | |
1290 | startups--; | |
1291 | } | |
48e671d5 | 1292 | for (i = 0; i < num_listen_socks; i++) { |
1293 | if (!FD_ISSET(listen_socks[i], fdset)) | |
5260325f | 1294 | continue; |
089fbbd2 | 1295 | fromlen = sizeof(from); |
1296 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
1297 | &fromlen); | |
1298 | if (newsock < 0) { | |
1299 | if (errno != EINTR && errno != EWOULDBLOCK) | |
1300 | error("accept: %.100s", strerror(errno)); | |
1301 | continue; | |
1302 | } | |
1303 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
1304 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
5e8948af | 1305 | close(newsock); |
089fbbd2 | 1306 | continue; |
1307 | } | |
c345cf9d | 1308 | if (drop_connection(startups) == 1) { |
1309 | debug("drop connection #%d", startups); | |
089fbbd2 | 1310 | close(newsock); |
1311 | continue; | |
1312 | } | |
1313 | if (pipe(startup_p) == -1) { | |
1314 | close(newsock); | |
1315 | continue; | |
1316 | } | |
1317 | ||
1318 | for (j = 0; j < options.max_startups; j++) | |
1319 | if (startup_pipes[j] == -1) { | |
1320 | startup_pipes[j] = startup_p[0]; | |
1321 | if (maxfd < startup_p[0]) | |
1322 | maxfd = startup_p[0]; | |
1323 | startups++; | |
1324 | break; | |
1325 | } | |
2b87da3b | 1326 | |
aa3378df | 1327 | /* |
089fbbd2 | 1328 | * Got connection. Fork a child to handle it, unless |
1329 | * we are in debugging mode. | |
aa3378df | 1330 | */ |
089fbbd2 | 1331 | if (debug_flag) { |
aa3378df | 1332 | /* |
089fbbd2 | 1333 | * In debugging mode. Close the listening |
1334 | * socket, and start processing the | |
1335 | * connection without forking. | |
aa3378df | 1336 | */ |
089fbbd2 | 1337 | debug("Server will not fork when running in debugging mode."); |
48e671d5 | 1338 | close_listen_socks(); |
5260325f | 1339 | sock_in = newsock; |
1340 | sock_out = newsock; | |
5540ea9b | 1341 | startup_pipe = -1; |
3f7a7e4a | 1342 | pid = getpid(); |
5260325f | 1343 | break; |
089fbbd2 | 1344 | } else { |
1345 | /* | |
1346 | * Normal production daemon. Fork, and have | |
1347 | * the child process the connection. The | |
1348 | * parent continues listening. | |
1349 | */ | |
1350 | if ((pid = fork()) == 0) { | |
1351 | /* | |
1352 | * Child. Close the listening and max_startup | |
1353 | * sockets. Start using the accepted socket. | |
1354 | * Reinitialize logging (since our pid has | |
1355 | * changed). We break out of the loop to handle | |
1356 | * the connection. | |
1357 | */ | |
1358 | startup_pipe = startup_p[1]; | |
7ace8c3b | 1359 | close_startup_pipes(); |
089fbbd2 | 1360 | close_listen_socks(); |
1361 | sock_in = newsock; | |
1362 | sock_out = newsock; | |
1fe6a48f | 1363 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
089fbbd2 | 1364 | break; |
1365 | } | |
5260325f | 1366 | } |
5260325f | 1367 | |
089fbbd2 | 1368 | /* Parent. Stay in the loop. */ |
1369 | if (pid < 0) | |
1370 | error("fork: %.100s", strerror(errno)); | |
1371 | else | |
c457707e | 1372 | debug("Forked child %ld.", (long)pid); |
5260325f | 1373 | |
089fbbd2 | 1374 | close(startup_p[1]); |
5260325f | 1375 | |
089fbbd2 | 1376 | /* Mark that the key has been used (it was "given" to the child). */ |
59c97189 | 1377 | if ((options.protocol & SSH_PROTO_1) && |
1378 | key_used == 0) { | |
1379 | /* Schedule server key regeneration alarm. */ | |
1380 | signal(SIGALRM, key_regeneration_alarm); | |
1381 | alarm(options.key_regeneration_time); | |
1382 | key_used = 1; | |
1383 | } | |
5260325f | 1384 | |
089fbbd2 | 1385 | arc4random_stir(); |
1386 | ||
1387 | /* Close the new socket (the child is now taking care of it). */ | |
1388 | close(newsock); | |
1389 | } | |
48e671d5 | 1390 | /* child process check (or debug mode) */ |
1391 | if (num_listen_socks < 0) | |
1392 | break; | |
5260325f | 1393 | } |
1394 | } | |
8efc0c15 | 1395 | |
5260325f | 1396 | /* This is the child processing a new connection. */ |
1397 | ||
4ac8556b | 1398 | /* |
1399 | * Create a new session and process group since the 4.4BSD | |
1400 | * setlogin() affects the entire process group. We don't | |
1401 | * want the child to be able to affect the parent. | |
1402 | */ | |
ad84c479 | 1403 | #if !defined(SSHD_ACQUIRES_CTTY) |
6ecd00f8 | 1404 | /* |
ad84c479 | 1405 | * If setsid is called, on some platforms sshd will later acquire a |
1406 | * controlling terminal which will result in "could not set | |
1407 | * controlling tty" errors. | |
6ecd00f8 | 1408 | */ |
c28876e9 | 1409 | if (!debug_flag && !inetd_flag && setsid() < 0) |
4ac8556b | 1410 | error("setsid: %.100s", strerror(errno)); |
30321a9b | 1411 | #endif |
4ac8556b | 1412 | |
aa3378df | 1413 | /* |
1414 | * Disable the key regeneration alarm. We will not regenerate the | |
1415 | * key since we are no longer in a position to give it to anyone. We | |
1416 | * will not restart on SIGHUP since it no longer makes sense. | |
1417 | */ | |
5260325f | 1418 | alarm(0); |
1419 | signal(SIGALRM, SIG_DFL); | |
1420 | signal(SIGHUP, SIG_DFL); | |
1421 | signal(SIGTERM, SIG_DFL); | |
1422 | signal(SIGQUIT, SIG_DFL); | |
1423 | signal(SIGCHLD, SIG_DFL); | |
9aaf9be4 | 1424 | signal(SIGINT, SIG_DFL); |
5260325f | 1425 | |
b5c334cc | 1426 | /* Set keepalives if requested. */ |
1427 | if (options.keepalives && | |
db518d9b | 1428 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, |
b5c334cc | 1429 | sizeof(on)) < 0) |
1430 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1431 | ||
aa3378df | 1432 | /* |
1433 | * Register our connection. This turns encryption off because we do | |
1434 | * not have a key. | |
1435 | */ | |
5260325f | 1436 | packet_set_connection(sock_in, sock_out); |
1437 | ||
1438 | remote_port = get_remote_port(); | |
1439 | remote_ip = get_remote_ipaddr(); | |
1440 | ||
5260325f | 1441 | #ifdef LIBWRAP |
ac28afd8 | 1442 | /* Check whether logins are denied from this host. */ |
5260325f | 1443 | { |
1444 | struct request_info req; | |
8efc0c15 | 1445 | |
8fbc356d | 1446 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); |
5260325f | 1447 | fromhost(&req); |
8efc0c15 | 1448 | |
5260325f | 1449 | if (!hosts_access(&req)) { |
ac28afd8 | 1450 | debug("Connection refused by tcp wrapper"); |
563834bb | 1451 | refuse(&req); |
ac28afd8 | 1452 | /* NOTREACHED */ |
1453 | fatal("libwrap refuse returns"); | |
5260325f | 1454 | } |
8efc0c15 | 1455 | } |
48e671d5 | 1456 | #endif /* LIBWRAP */ |
ac28afd8 | 1457 | |
5260325f | 1458 | /* Log the connection. */ |
1459 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
8efc0c15 | 1460 | |
aa3378df | 1461 | /* |
1462 | * We don\'t want to listen forever unless the other side | |
1463 | * successfully authenticates itself. So we set up an alarm which is | |
1464 | * cleared after successful authentication. A limit of zero | |
1465 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1466 | * mode; it is just annoying to have the server exit just when you | |
1467 | * are about to discover the bug. | |
1468 | */ | |
5260325f | 1469 | signal(SIGALRM, grace_alarm_handler); |
1470 | if (!debug_flag) | |
1471 | alarm(options.login_grace_time); | |
1472 | ||
7368a6c8 | 1473 | sshd_exchange_identification(sock_in, sock_out); |
aa3378df | 1474 | /* |
6ffc9c88 | 1475 | * Check that the connection comes from a privileged port. |
c242fc96 | 1476 | * Rhosts-Authentication only makes sense from privileged |
aa3378df | 1477 | * programs. Of course, if the intruder has root access on his local |
1478 | * machine, he can connect from any port. So do not use these | |
1479 | * authentication methods from machines that you do not trust. | |
1480 | */ | |
44b1a8e5 | 1481 | if (options.rhosts_authentication && |
1482 | (remote_port >= IPPORT_RESERVED || | |
1483 | remote_port < IPPORT_RESERVED / 2)) { | |
6ffc9c88 | 1484 | debug("Rhosts Authentication disabled, " |
9ae3f727 | 1485 | "originating port %d not trusted.", remote_port); |
5260325f | 1486 | options.rhosts_authentication = 0; |
5260325f | 1487 | } |
ced49be2 | 1488 | #if defined(KRB4) && !defined(KRB5) |
48e671d5 | 1489 | if (!packet_connection_is_ipv4() && |
1490 | options.kerberos_authentication) { | |
1491 | debug("Kerberos Authentication disabled, only available for IPv4."); | |
1492 | options.kerberos_authentication = 0; | |
1493 | } | |
ced49be2 | 1494 | #endif /* KRB4 && !KRB5 */ |
abf1f107 | 1495 | #ifdef AFS |
1496 | /* If machine has AFS, set process authentication group. */ | |
1497 | if (k_hasafs()) { | |
1498 | k_setpag(); | |
1499 | k_unlog(); | |
1500 | } | |
1501 | #endif /* AFS */ | |
48e671d5 | 1502 | |
5260325f | 1503 | packet_set_nonblocking(); |
1504 | ||
324bf712 | 1505 | if (use_privsep) |
1506 | if ((authctxt = privsep_preauth()) != NULL) | |
1507 | goto authenticated; | |
1853d1ef | 1508 | |
7b2ea3a1 | 1509 | /* perform the key exchange */ |
7b2ea3a1 | 1510 | /* authenticate user and start session */ |
e78a59f5 | 1511 | if (compat20) { |
1512 | do_ssh2_kex(); | |
1b34c1b3 | 1513 | authctxt = do_authentication2(); |
e78a59f5 | 1514 | } else { |
1515 | do_ssh1_kex(); | |
1b34c1b3 | 1516 | authctxt = do_authentication(); |
e78a59f5 | 1517 | } |
324bf712 | 1518 | /* |
1519 | * If we use privilege separation, the unprivileged child transfers | |
1520 | * the current keystate and exits | |
1521 | */ | |
1522 | if (use_privsep) { | |
b5a28cbc | 1523 | mm_send_keystate(pmonitor); |
1853d1ef | 1524 | exit(0); |
324bf712 | 1525 | } |
1853d1ef | 1526 | |
1527 | authenticated: | |
762715ce | 1528 | /* |
1853d1ef | 1529 | * In privilege separation, we fork another child and prepare |
1530 | * file descriptor passing. | |
1531 | */ | |
1532 | if (use_privsep) { | |
324bf712 | 1533 | privsep_postauth(authctxt); |
1534 | /* the monitor process [priv] will not return */ | |
1853d1ef | 1535 | if (!compat20) |
1536 | destroy_sensitive_data(); | |
1537 | } | |
1b34c1b3 | 1538 | |
1539 | /* Perform session preparation. */ | |
1540 | do_authenticated(authctxt); | |
1541 | ||
63284fbb | 1542 | /* The connection has been terminated. */ |
1543 | verbose("Closing connection to %.100s", remote_ip); | |
8efc0c15 | 1544 | |
d94aa2ae | 1545 | #ifdef USE_PAM |
7fceb20d | 1546 | if (options.use_pam) |
1547 | finish_pam(); | |
d94aa2ae | 1548 | #endif /* USE_PAM */ |
8efc0c15 | 1549 | |
5260325f | 1550 | packet_close(); |
1853d1ef | 1551 | |
1552 | if (use_privsep) | |
1553 | mm_terminate(); | |
1554 | ||
5260325f | 1555 | exit(0); |
1556 | } | |
8efc0c15 | 1557 | |
4f08e98d | 1558 | /* |
1559 | * Decrypt session_key_int using our private server key and private host key | |
1560 | * (key with larger modulus first). | |
1561 | */ | |
1853d1ef | 1562 | int |
4f08e98d | 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 | } | |
5260325f | 1602 | /* |
7b2ea3a1 | 1603 | * SSH1 key exchange |
5260325f | 1604 | */ |
396c147e | 1605 | static void |
1e3b8b07 | 1606 | do_ssh1_kex(void) |
8efc0c15 | 1607 | { |
5260325f | 1608 | int i, len; |
46aa2d1f | 1609 | int rsafail = 0; |
5260325f | 1610 | BIGNUM *session_key_int; |
1e3b8b07 | 1611 | u_char session_key[SSH_SESSION_KEY_LENGTH]; |
1612 | u_char cookie[8]; | |
1613 | u_int cipher_type, auth_mask, protocol_flags; | |
7fdc56c5 | 1614 | u_int32_t rnd = 0; |
5260325f | 1615 | |
aa3378df | 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 | */ | |
5260325f | 1625 | for (i = 0; i < 8; i++) { |
1626 | if (i % 4 == 0) | |
7fdc56c5 | 1627 | rnd = arc4random(); |
1628 | cookie[i] = rnd & 0xff; | |
1629 | rnd >>= 8; | |
5260325f | 1630 | } |
1631 | ||
aa3378df | 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 | */ | |
5260325f | 1637 | packet_start(SSH_SMSG_PUBLIC_KEY); |
1638 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1639 | packet_put_char(cookie[i]); |
5260325f | 1640 | |
1641 | /* Store our public server RSA key. */ | |
fa08c86b | 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); | |
5260325f | 1645 | |
1646 | /* Store our public host RSA key. */ | |
fa08c86b | 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); | |
5260325f | 1650 | |
1651 | /* Put protocol flags. */ | |
1652 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1653 | ||
1654 | /* Declare which ciphers we support. */ | |
94ec8c6b | 1655 | packet_put_int(cipher_mask_ssh1(0)); |
5260325f | 1656 | |
1657 | /* Declare supported authentication types. */ | |
1658 | auth_mask = 0; | |
1659 | if (options.rhosts_authentication) | |
1660 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
1661 | if (options.rhosts_rsa_authentication) | |
1662 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1663 | if (options.rsa_authentication) | |
1664 | auth_mask |= 1 << SSH_AUTH_RSA; | |
ced49be2 | 1665 | #if defined(KRB4) || defined(KRB5) |
5260325f | 1666 | if (options.kerberos_authentication) |
1667 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
8efc0c15 | 1668 | #endif |
ced49be2 | 1669 | #if defined(AFS) || defined(KRB5) |
5260325f | 1670 | if (options.kerberos_tgt_passing) |
1671 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
ced49be2 | 1672 | #endif |
1673 | #ifdef AFS | |
5260325f | 1674 | if (options.afs_token_passing) |
1675 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
8efc0c15 | 1676 | #endif |
5ba55ada | 1677 | if (options.challenge_response_authentication == 1) |
5260325f | 1678 | auth_mask |= 1 << SSH_AUTH_TIS; |
5260325f | 1679 | if (options.password_authentication) |
1680 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1681 | packet_put_int(auth_mask); | |
1682 | ||
1683 | /* Send the packet and wait for it to be sent. */ | |
1684 | packet_send(); | |
1685 | packet_write_wait(); | |
1686 | ||
fa08c86b | 1687 | debug("Sent %d bit server key and %d bit host key.", |
1688 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1689 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
5260325f | 1690 | |
1691 | /* Read clients reply (cipher type and session key). */ | |
54a5250f | 1692 | packet_read_expect(SSH_CMSG_SESSION_KEY); |
5260325f | 1693 | |
2d86a6cc | 1694 | /* Get cipher type and check whether we accept this. */ |
5260325f | 1695 | cipher_type = packet_get_char(); |
1696 | ||
94ec8c6b | 1697 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) |
2d86a6cc | 1698 | packet_disconnect("Warning: client selects unsupported cipher."); |
1699 | ||
5260325f | 1700 | /* Get check bytes from the packet. These must match those we |
1701 | sent earlier with the public key packet. */ | |
1702 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1703 | if (cookie[i] != packet_get_char()) |
5260325f | 1704 | packet_disconnect("IP Spoofing check bytes do not match."); |
1705 | ||
1706 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1707 | ||
1708 | /* Get the encrypted integer. */ | |
b775c6f2 | 1709 | if ((session_key_int = BN_new()) == NULL) |
1710 | fatal("do_ssh1_kex: BN_new failed"); | |
20b279e6 | 1711 | packet_get_bignum(session_key_int); |
5260325f | 1712 | |
5260325f | 1713 | protocol_flags = packet_get_int(); |
1714 | packet_set_protocol_flags(protocol_flags); | |
95500969 | 1715 | packet_check_eom(); |
5260325f | 1716 | |
4f08e98d | 1717 | /* Decrypt session_key_int using host/server keys */ |
1853d1ef | 1718 | rsafail = PRIVSEP(ssh1_session_key(session_key_int)); |
1719 | ||
aa3378df | 1720 | /* |
1721 | * Extract session key from the decrypted integer. The key is in the | |
1722 | * least significant 256 bits of the integer; the first byte of the | |
1723 | * key is in the highest bits. | |
1724 | */ | |
46aa2d1f | 1725 | if (!rsafail) { |
1726 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
1727 | len = BN_num_bytes(session_key_int); | |
1728 | if (len < 0 || len > sizeof(session_key)) { | |
1729 | error("do_connection: bad session key len from %s: " | |
5ca51e19 | 1730 | "session_key_int %d > sizeof(session_key) %lu", |
1731 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); | |
46aa2d1f | 1732 | rsafail++; |
1733 | } else { | |
1734 | memset(session_key, 0, sizeof(session_key)); | |
1735 | BN_bn2bin(session_key_int, | |
1736 | session_key + sizeof(session_key) - len); | |
00be5382 | 1737 | |
1738 | compute_session_id(session_id, cookie, | |
1739 | sensitive_data.ssh1_host_key->rsa->n, | |
1740 | sensitive_data.server_key->rsa->n); | |
1741 | /* | |
1742 | * Xor the first 16 bytes of the session key with the | |
1743 | * session id. | |
1744 | */ | |
1745 | for (i = 0; i < 16; i++) | |
1746 | session_key[i] ^= session_id[i]; | |
46aa2d1f | 1747 | } |
1748 | } | |
1749 | if (rsafail) { | |
00be5382 | 1750 | int bytes = BN_num_bytes(session_key_int); |
f6b1ba8f | 1751 | u_char *buf = xmalloc(bytes); |
00be5382 | 1752 | MD5_CTX md; |
1753 | ||
bbe88b6d | 1754 | logit("do_connection: generating a fake encryption key"); |
00be5382 | 1755 | BN_bn2bin(session_key_int, buf); |
1756 | MD5_Init(&md); | |
1757 | MD5_Update(&md, buf, bytes); | |
1758 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1759 | MD5_Final(session_key, &md); | |
1760 | MD5_Init(&md); | |
1761 | MD5_Update(&md, session_key, 16); | |
1762 | MD5_Update(&md, buf, bytes); | |
1763 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1764 | MD5_Final(session_key + 16, &md); | |
1765 | memset(buf, 0, bytes); | |
1766 | xfree(buf); | |
0572fe75 | 1767 | for (i = 0; i < 16; i++) |
1768 | session_id[i] = session_key[i] ^ session_key[i + 16]; | |
46aa2d1f | 1769 | } |
1853d1ef | 1770 | /* Destroy the private and public keys. No longer. */ |
63284fbb | 1771 | destroy_sensitive_data(); |
00be5382 | 1772 | |
1853d1ef | 1773 | if (use_privsep) |
1774 | mm_ssh1_session_id(session_id); | |
1775 | ||
7b2ea3a1 | 1776 | /* Destroy the decrypted integer. It is no longer needed. */ |
1777 | BN_clear_free(session_key_int); | |
1778 | ||
5260325f | 1779 | /* Set the session key. From this on all communications will be encrypted. */ |
1780 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1781 | ||
1782 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1783 | memset(session_key, 0, sizeof(session_key)); | |
1784 | ||
1785 | debug("Received session key; encryption turned on."); | |
1786 | ||
c242fc96 | 1787 | /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ |
5260325f | 1788 | packet_start(SSH_SMSG_SUCCESS); |
1789 | packet_send(); | |
1790 | packet_write_wait(); | |
5260325f | 1791 | } |
e78a59f5 | 1792 | |
1793 | /* | |
1794 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1795 | */ | |
396c147e | 1796 | static void |
1e3b8b07 | 1797 | do_ssh2_kex(void) |
e78a59f5 | 1798 | { |
e78a59f5 | 1799 | Kex *kex; |
e78a59f5 | 1800 | |
a8be9f80 | 1801 | if (options.ciphers != NULL) { |
6ae2364d | 1802 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
a8be9f80 | 1803 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
1804 | } | |
1ad64a93 | 1805 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
1806 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); | |
1807 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
1808 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); | |
1809 | ||
b2552997 | 1810 | if (options.macs != NULL) { |
1811 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
1812 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
1813 | } | |
636f76ca | 1814 | if (!options.compression) { |
1815 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
1816 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
1817 | } | |
fa08c86b | 1818 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
1819 | ||
7a37c112 | 1820 | /* start key exchange */ |
d8ee838b | 1821 | kex = kex_setup(myproposal); |
98a58eda | 1822 | kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; |
1823 | kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; | |
a5c9ffdb | 1824 | kex->server = 1; |
1825 | kex->client_version_string=client_version_string; | |
1826 | kex->server_version_string=server_version_string; | |
1827 | kex->load_host_key=&get_hostkey_by_type; | |
1853d1ef | 1828 | kex->host_key_index=&get_hostkey_index; |
94ec8c6b | 1829 | |
7a37c112 | 1830 | xxx_kex = kex; |
1831 | ||
c422989b | 1832 | dispatch_run(DISPATCH_BLOCK, &kex->done, kex); |
94ec8c6b | 1833 | |
d1ac6175 | 1834 | session_id2 = kex->session_id; |
1835 | session_id2_len = kex->session_id_len; | |
1836 | ||
94ec8c6b | 1837 | #ifdef DEBUG_KEXDH |
1838 | /* send 1st encrypted/maced/compressed message */ | |
1839 | packet_start(SSH2_MSG_IGNORE); | |
1840 | packet_put_cstring("markus"); | |
1841 | packet_send(); | |
1842 | packet_write_wait(); | |
1843 | #endif | |
a5c9ffdb | 1844 | debug("KEX done"); |
e78a59f5 | 1845 | } |