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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" | |
324bf712 | 45 | RCSID("$OpenBSD: sshd.c,v 1.237 2002/03/21 21:23:34 markus 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> |
42f11eb2 | 51 | |
52 | #include "ssh.h" | |
53 | #include "ssh1.h" | |
54 | #include "ssh2.h" | |
8efc0c15 | 55 | #include "xmalloc.h" |
56 | #include "rsa.h" | |
1729c161 | 57 | #include "sshpty.h" |
8efc0c15 | 58 | #include "packet.h" |
8efc0c15 | 59 | #include "mpaux.h" |
42f11eb2 | 60 | #include "log.h" |
8efc0c15 | 61 | #include "servconf.h" |
62 | #include "uidswap.h" | |
63 | #include "compat.h" | |
7368a6c8 | 64 | #include "buffer.h" |
42f11eb2 | 65 | #include "cipher.h" |
e78a59f5 | 66 | #include "kex.h" |
7368a6c8 | 67 | #include "key.h" |
94ec8c6b | 68 | #include "dh.h" |
e78a59f5 | 69 | #include "myproposal.h" |
a306f2dd | 70 | #include "authfile.h" |
42f11eb2 | 71 | #include "pathnames.h" |
72 | #include "atomicio.h" | |
73 | #include "canohost.h" | |
74 | #include "auth.h" | |
75 | #include "misc.h" | |
a5c9ffdb | 76 | #include "dispatch.h" |
e4d7f734 | 77 | #include "channels.h" |
1b34c1b3 | 78 | #include "session.h" |
1853d1ef | 79 | #include "monitor_mm.h" |
80 | #include "monitor.h" | |
81 | #include "monitor_wrap.h" | |
82 | #include "monitor_fdpass.h" | |
8efc0c15 | 83 | |
84 | #ifdef LIBWRAP | |
85 | #include <tcpd.h> | |
86 | #include <syslog.h> | |
87 | int allow_severity = LOG_INFO; | |
88 | int deny_severity = LOG_WARNING; | |
89 | #endif /* LIBWRAP */ | |
90 | ||
91 | #ifndef O_NOCTTY | |
92 | #define O_NOCTTY 0 | |
93 | #endif | |
94 | ||
260d427b | 95 | #ifdef HAVE___PROGNAME |
96 | extern char *__progname; | |
97 | #else | |
98 | char *__progname; | |
99 | #endif | |
100 | ||
8efc0c15 | 101 | /* Server configuration options. */ |
102 | ServerOptions options; | |
103 | ||
104 | /* Name of the server configuration file. */ | |
42f11eb2 | 105 | char *config_file_name = _PATH_SERVER_CONFIG_FILE; |
8efc0c15 | 106 | |
6ae2364d | 107 | /* |
48e671d5 | 108 | * Flag indicating whether IPv4 or IPv6. This can be set on the command line. |
109 | * Default value is AF_UNSPEC means both IPv4 and IPv6. | |
110 | */ | |
59e76f33 | 111 | #ifdef IPV4_DEFAULT |
112 | int IPv4or6 = AF_INET; | |
113 | #else | |
48e671d5 | 114 | int IPv4or6 = AF_UNSPEC; |
59e76f33 | 115 | #endif |
48e671d5 | 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 */ |
201 | extern struct monitor *monitor; | |
202 | extern int use_privsep; | |
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; | |
218 | for (i = 0; i < num_listen_socks; i++) | |
219 | close(listen_socks[i]); | |
220 | num_listen_socks = -1; | |
221 | } | |
222 | ||
7ace8c3b | 223 | static void |
224 | close_startup_pipes(void) | |
225 | { | |
226 | int i; | |
227 | if (startup_pipes) | |
228 | for (i = 0; i < options.max_startups; i++) | |
229 | if (startup_pipes[i] != -1) | |
230 | close(startup_pipes[i]); | |
231 | } | |
232 | ||
5260325f | 233 | /* |
234 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
235 | * the effect is to reread the configuration file (and to regenerate | |
236 | * the server key). | |
237 | */ | |
396c147e | 238 | static void |
5260325f | 239 | sighup_handler(int sig) |
8efc0c15 | 240 | { |
6056eb35 | 241 | int save_errno = errno; |
242 | ||
5260325f | 243 | received_sighup = 1; |
244 | signal(SIGHUP, sighup_handler); | |
6056eb35 | 245 | errno = save_errno; |
8efc0c15 | 246 | } |
247 | ||
5260325f | 248 | /* |
249 | * Called from the main program after receiving SIGHUP. | |
250 | * Restarts the server. | |
251 | */ | |
396c147e | 252 | static void |
5ca51e19 | 253 | sighup_restart(void) |
8efc0c15 | 254 | { |
5260325f | 255 | log("Received SIGHUP; restarting."); |
48e671d5 | 256 | close_listen_socks(); |
7ace8c3b | 257 | close_startup_pipes(); |
5260325f | 258 | execv(saved_argv[0], saved_argv); |
1fe6a48f | 259 | log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno)); |
5260325f | 260 | exit(1); |
8efc0c15 | 261 | } |
262 | ||
5260325f | 263 | /* |
264 | * Generic signal handler for terminating signals in the master daemon. | |
5260325f | 265 | */ |
396c147e | 266 | static void |
5260325f | 267 | sigterm_handler(int sig) |
8efc0c15 | 268 | { |
c9130033 | 269 | received_sigterm = sig; |
8efc0c15 | 270 | } |
271 | ||
5260325f | 272 | /* |
273 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
c9130033 | 274 | * reap any zombies left by exited children. |
5260325f | 275 | */ |
396c147e | 276 | static void |
5260325f | 277 | main_sigchld_handler(int sig) |
8efc0c15 | 278 | { |
5260325f | 279 | int save_errno = errno; |
280 | int status; | |
5ad13cd7 | 281 | |
5260325f | 282 | while (waitpid(-1, &status, WNOHANG) > 0) |
283 | ; | |
5ad13cd7 | 284 | |
5260325f | 285 | signal(SIGCHLD, main_sigchld_handler); |
286 | errno = save_errno; | |
8efc0c15 | 287 | } |
288 | ||
5260325f | 289 | /* |
290 | * Signal handler for the alarm after the login grace period has expired. | |
291 | */ | |
396c147e | 292 | static void |
5260325f | 293 | grace_alarm_handler(int sig) |
8efc0c15 | 294 | { |
c9130033 | 295 | /* XXX no idea how fix this signal handler */ |
296 | ||
5260325f | 297 | /* Close the connection. */ |
298 | packet_close(); | |
8efc0c15 | 299 | |
5260325f | 300 | /* Log error and exit. */ |
301 | fatal("Timeout before authentication for %s.", get_remote_ipaddr()); | |
302 | } | |
8efc0c15 | 303 | |
5260325f | 304 | /* |
305 | * Signal handler for the key regeneration alarm. Note that this | |
306 | * alarm only occurs in the daemon waiting for connections, and it does not | |
307 | * do anything with the private key or random state before forking. | |
308 | * Thus there should be no concurrency control/asynchronous execution | |
309 | * problems. | |
310 | */ | |
396c147e | 311 | static void |
cb7bd922 | 312 | generate_ephemeral_server_key(void) |
fa08c86b | 313 | { |
00be5382 | 314 | u_int32_t rand = 0; |
315 | int i; | |
316 | ||
cd332296 | 317 | verbose("Generating %s%d bit RSA key.", |
76ca7b01 | 318 | sensitive_data.server_key ? "new " : "", options.server_key_bits); |
fa08c86b | 319 | if (sensitive_data.server_key != NULL) |
320 | key_free(sensitive_data.server_key); | |
cd332296 | 321 | sensitive_data.server_key = key_generate(KEY_RSA1, |
76ca7b01 | 322 | options.server_key_bits); |
323 | verbose("RSA key generation complete."); | |
00be5382 | 324 | |
325 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
326 | if (i % 4 == 0) | |
327 | rand = arc4random(); | |
328 | sensitive_data.ssh1_cookie[i] = rand & 0xff; | |
329 | rand >>= 8; | |
330 | } | |
331 | arc4random_stir(); | |
fa08c86b | 332 | } |
f546c780 | 333 | |
396c147e | 334 | static void |
5260325f | 335 | key_regeneration_alarm(int sig) |
336 | { | |
337 | int save_errno = errno; | |
59c97189 | 338 | signal(SIGALRM, SIG_DFL); |
5260325f | 339 | errno = save_errno; |
59c97189 | 340 | key_do_regen = 1; |
5260325f | 341 | } |
8efc0c15 | 342 | |
396c147e | 343 | static void |
7368a6c8 | 344 | sshd_exchange_identification(int sock_in, int sock_out) |
345 | { | |
a8be9f80 | 346 | int i, mismatch; |
7368a6c8 | 347 | int remote_major, remote_minor; |
a8be9f80 | 348 | int major, minor; |
7368a6c8 | 349 | char *s; |
350 | char buf[256]; /* Must not be larger than remote_version. */ | |
351 | char remote_version[256]; /* Must be at least as big as buf. */ | |
352 | ||
a8be9f80 | 353 | if ((options.protocol & SSH_PROTO_1) && |
354 | (options.protocol & SSH_PROTO_2)) { | |
355 | major = PROTOCOL_MAJOR_1; | |
356 | minor = 99; | |
357 | } else if (options.protocol & SSH_PROTO_2) { | |
358 | major = PROTOCOL_MAJOR_2; | |
359 | minor = PROTOCOL_MINOR_2; | |
360 | } else { | |
361 | major = PROTOCOL_MAJOR_1; | |
362 | minor = PROTOCOL_MINOR_1; | |
363 | } | |
364 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
7368a6c8 | 365 | server_version_string = xstrdup(buf); |
366 | ||
367 | if (client_version_string == NULL) { | |
368 | /* Send our protocol version identification. */ | |
369 | if (atomicio(write, sock_out, server_version_string, strlen(server_version_string)) | |
370 | != strlen(server_version_string)) { | |
30f60c34 | 371 | log("Could not write ident string to %s", get_remote_ipaddr()); |
7368a6c8 | 372 | fatal_cleanup(); |
373 | } | |
374 | ||
2ce1adf9 | 375 | /* Read other side's version identification. */ |
cd332296 | 376 | memset(buf, 0, sizeof(buf)); |
7368a6c8 | 377 | for (i = 0; i < sizeof(buf) - 1; i++) { |
e5a0294f | 378 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { |
30f60c34 | 379 | log("Did not receive identification string from %s", |
c2b544a5 | 380 | get_remote_ipaddr()); |
7368a6c8 | 381 | fatal_cleanup(); |
382 | } | |
383 | if (buf[i] == '\r') { | |
8a169574 | 384 | buf[i] = 0; |
94ec8c6b | 385 | /* Kludge for F-Secure Macintosh < 1.0.2 */ |
386 | if (i == 12 && | |
387 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
388 | break; | |
7368a6c8 | 389 | continue; |
7368a6c8 | 390 | } |
391 | if (buf[i] == '\n') { | |
8a169574 | 392 | buf[i] = 0; |
7368a6c8 | 393 | break; |
394 | } | |
395 | } | |
396 | buf[sizeof(buf) - 1] = 0; | |
397 | client_version_string = xstrdup(buf); | |
398 | } | |
399 | ||
400 | /* | |
401 | * Check that the versions match. In future this might accept | |
402 | * several versions and set appropriate flags to handle them. | |
403 | */ | |
404 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
405 | &remote_major, &remote_minor, remote_version) != 3) { | |
6ae2364d | 406 | s = "Protocol mismatch.\n"; |
7368a6c8 | 407 | (void) atomicio(write, sock_out, s, strlen(s)); |
408 | close(sock_in); | |
409 | close(sock_out); | |
410 | log("Bad protocol version identification '%.100s' from %s", | |
411 | client_version_string, get_remote_ipaddr()); | |
412 | fatal_cleanup(); | |
413 | } | |
414 | debug("Client protocol version %d.%d; client software version %.100s", | |
184eed6a | 415 | remote_major, remote_minor, remote_version); |
7368a6c8 | 416 | |
e78a59f5 | 417 | compat_datafellows(remote_version); |
418 | ||
3a1c54d4 | 419 | if (datafellows & SSH_BUG_SCANNER) { |
420 | log("scanned from %s with %s. Don't panic.", | |
421 | get_remote_ipaddr(), client_version_string); | |
422 | fatal_cleanup(); | |
423 | } | |
424 | ||
a8be9f80 | 425 | mismatch = 0; |
6aacefa7 | 426 | switch (remote_major) { |
7368a6c8 | 427 | case 1: |
a306f2dd | 428 | if (remote_minor == 99) { |
429 | if (options.protocol & SSH_PROTO_2) | |
430 | enable_compat20(); | |
431 | else | |
432 | mismatch = 1; | |
433 | break; | |
434 | } | |
a8be9f80 | 435 | if (!(options.protocol & SSH_PROTO_1)) { |
436 | mismatch = 1; | |
437 | break; | |
438 | } | |
7368a6c8 | 439 | if (remote_minor < 3) { |
089fbbd2 | 440 | packet_disconnect("Your ssh version is too old and " |
7368a6c8 | 441 | "is no longer supported. Please install a newer version."); |
442 | } else if (remote_minor == 3) { | |
443 | /* note that this disables agent-forwarding */ | |
444 | enable_compat13(); | |
445 | } | |
a8be9f80 | 446 | break; |
e78a59f5 | 447 | case 2: |
a8be9f80 | 448 | if (options.protocol & SSH_PROTO_2) { |
e78a59f5 | 449 | enable_compat20(); |
450 | break; | |
451 | } | |
452 | /* FALLTHROUGH */ | |
6ae2364d | 453 | default: |
a8be9f80 | 454 | mismatch = 1; |
455 | break; | |
456 | } | |
457 | chop(server_version_string); | |
a8be9f80 | 458 | debug("Local version string %.200s", server_version_string); |
459 | ||
460 | if (mismatch) { | |
7368a6c8 | 461 | s = "Protocol major versions differ.\n"; |
462 | (void) atomicio(write, sock_out, s, strlen(s)); | |
463 | close(sock_in); | |
464 | close(sock_out); | |
a8be9f80 | 465 | log("Protocol major versions differ for %s: %.200s vs. %.200s", |
466 | get_remote_ipaddr(), | |
467 | server_version_string, client_version_string); | |
7368a6c8 | 468 | fatal_cleanup(); |
7368a6c8 | 469 | } |
a306f2dd | 470 | } |
471 | ||
472 | ||
fa08c86b | 473 | /* Destroy the host and server keys. They will no longer be needed. */ |
a306f2dd | 474 | void |
475 | destroy_sensitive_data(void) | |
476 | { | |
fa08c86b | 477 | int i; |
478 | ||
479 | if (sensitive_data.server_key) { | |
480 | key_free(sensitive_data.server_key); | |
481 | sensitive_data.server_key = NULL; | |
482 | } | |
184eed6a | 483 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 484 | if (sensitive_data.host_keys[i]) { |
485 | key_free(sensitive_data.host_keys[i]); | |
486 | sensitive_data.host_keys[i] = NULL; | |
487 | } | |
488 | } | |
489 | sensitive_data.ssh1_host_key = NULL; | |
00be5382 | 490 | memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); |
fa08c86b | 491 | } |
fa08c86b | 492 | |
1853d1ef | 493 | /* Demote private to public keys for network child */ |
494 | void | |
495 | demote_sensitive_data(void) | |
496 | { | |
497 | Key *tmp; | |
498 | int i; | |
499 | ||
500 | if (sensitive_data.server_key) { | |
501 | tmp = key_demote(sensitive_data.server_key); | |
502 | key_free(sensitive_data.server_key); | |
503 | sensitive_data.server_key = tmp; | |
504 | } | |
505 | ||
506 | for (i = 0; i < options.num_host_key_files; i++) { | |
507 | if (sensitive_data.host_keys[i]) { | |
508 | tmp = key_demote(sensitive_data.host_keys[i]); | |
509 | key_free(sensitive_data.host_keys[i]); | |
510 | sensitive_data.host_keys[i] = tmp; | |
511 | if (tmp->type == KEY_RSA1) | |
512 | sensitive_data.ssh1_host_key = tmp; | |
513 | } | |
514 | } | |
515 | ||
516 | /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ | |
517 | } | |
518 | ||
51aeb639 | 519 | static void |
1853d1ef | 520 | privsep_preauth_child(void) |
521 | { | |
522 | u_int32_t rand[256]; | |
523 | int i; | |
2ea6de2b | 524 | struct passwd *pw; |
1853d1ef | 525 | |
526 | /* Enable challenge-response authentication for privilege separation */ | |
527 | privsep_challenge_enable(); | |
528 | ||
529 | for (i = 0; i < 256; i++) | |
530 | rand[i] = arc4random(); | |
531 | RAND_seed(rand, sizeof(rand)); | |
532 | ||
533 | /* Demote the private keys to public keys. */ | |
534 | demote_sensitive_data(); | |
535 | ||
2ea6de2b | 536 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) |
537 | fatal("%s: no user", SSH_PRIVSEP_USER); | |
538 | memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); | |
539 | endpwent(); | |
540 | ||
1853d1ef | 541 | /* Change our root directory*/ |
1c352e97 | 542 | if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) |
543 | fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, | |
544 | strerror(errno)); | |
1853d1ef | 545 | if (chdir("/") == -1) |
edfb66cb | 546 | fatal("chdir(\"/\"): %s", strerror(errno)); |
762715ce | 547 | |
1853d1ef | 548 | /* Drop our privileges */ |
2ea6de2b | 549 | debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, |
550 | (u_int)pw->pw_gid); | |
551 | do_setusercontext(pw); | |
1853d1ef | 552 | } |
553 | ||
324bf712 | 554 | static Authctxt* |
555 | privsep_preauth(void) | |
1853d1ef | 556 | { |
324bf712 | 557 | Authctxt *authctxt = NULL; |
1853d1ef | 558 | int status; |
324bf712 | 559 | pid_t pid; |
1853d1ef | 560 | |
324bf712 | 561 | /* Set up unprivileged child process to deal with network data */ |
562 | monitor = monitor_init(); | |
563 | /* Store a pointer to the kex for later rekeying */ | |
564 | monitor->m_pkex = &xxx_kex; | |
565 | ||
566 | pid = fork(); | |
567 | if (pid == -1) { | |
568 | fatal("fork of unprivileged child failed"); | |
569 | } else if (pid != 0) { | |
570 | debug2("Network child is on pid %d", pid); | |
571 | ||
572 | close(monitor->m_recvfd); | |
573 | authctxt = monitor_child_preauth(monitor); | |
574 | close(monitor->m_sendfd); | |
575 | ||
576 | /* Sync memory */ | |
577 | monitor_sync(monitor); | |
578 | ||
579 | /* Wait for the child's exit status */ | |
580 | waitpid(pid, &status, 0); | |
581 | ||
582 | return (authctxt); | |
583 | } else { | |
584 | /* child */ | |
585 | ||
586 | close(monitor->m_sendfd); | |
587 | ||
588 | /* Demote the child */ | |
589 | if (getuid() == 0 || geteuid() == 0) | |
590 | privsep_preauth_child(); | |
591 | } | |
592 | return (NULL); | |
593 | } | |
594 | ||
595 | static void | |
596 | privsep_postauth(Authctxt *authctxt) | |
597 | { | |
598 | extern Authctxt *x_authctxt; | |
1853d1ef | 599 | |
600 | /* XXX - Remote port forwarding */ | |
601 | x_authctxt = authctxt; | |
602 | ||
603 | if (authctxt->pw->pw_uid == 0 || options.use_login) { | |
604 | /* File descriptor passing is broken or root login */ | |
605 | monitor_apply_keystate(monitor); | |
606 | use_privsep = 0; | |
607 | return; | |
608 | } | |
762715ce | 609 | |
1853d1ef | 610 | /* Authentication complete */ |
611 | alarm(0); | |
612 | if (startup_pipe != -1) { | |
613 | close(startup_pipe); | |
614 | startup_pipe = -1; | |
615 | } | |
616 | ||
617 | /* New socket pair */ | |
618 | monitor_reinit(monitor); | |
619 | ||
620 | monitor->m_pid = fork(); | |
621 | if (monitor->m_pid == -1) | |
622 | fatal("fork of unprivileged child failed"); | |
623 | else if (monitor->m_pid != 0) { | |
324bf712 | 624 | debug2("User child is on pid %d", monitor->m_pid); |
1853d1ef | 625 | close(monitor->m_recvfd); |
626 | monitor_child_postauth(monitor); | |
627 | ||
628 | /* NEVERREACHED */ | |
629 | exit(0); | |
630 | } | |
631 | ||
632 | close(monitor->m_sendfd); | |
633 | ||
634 | /* Demote the private keys to public keys. */ | |
635 | demote_sensitive_data(); | |
636 | ||
637 | /* Drop privileges */ | |
638 | do_setusercontext(authctxt->pw); | |
639 | ||
640 | /* It is safe now to apply the key state */ | |
641 | monitor_apply_keystate(monitor); | |
642 | } | |
643 | ||
396c147e | 644 | static char * |
fa08c86b | 645 | list_hostkey_types(void) |
646 | { | |
3469eac4 | 647 | Buffer b; |
648 | char *p; | |
fa08c86b | 649 | int i; |
3469eac4 | 650 | |
651 | buffer_init(&b); | |
184eed6a | 652 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 653 | Key *key = sensitive_data.host_keys[i]; |
654 | if (key == NULL) | |
655 | continue; | |
6aacefa7 | 656 | switch (key->type) { |
fa08c86b | 657 | case KEY_RSA: |
658 | case KEY_DSA: | |
3469eac4 | 659 | if (buffer_len(&b) > 0) |
660 | buffer_append(&b, ",", 1); | |
661 | p = key_ssh_name(key); | |
662 | buffer_append(&b, p, strlen(p)); | |
fa08c86b | 663 | break; |
664 | } | |
665 | } | |
3469eac4 | 666 | buffer_append(&b, "\0", 1); |
667 | p = xstrdup(buffer_ptr(&b)); | |
668 | buffer_free(&b); | |
669 | debug("list_hostkey_types: %s", p); | |
670 | return p; | |
fa08c86b | 671 | } |
672 | ||
1853d1ef | 673 | Key * |
fa08c86b | 674 | get_hostkey_by_type(int type) |
675 | { | |
676 | int i; | |
184eed6a | 677 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 678 | Key *key = sensitive_data.host_keys[i]; |
679 | if (key != NULL && key->type == type) | |
680 | return key; | |
681 | } | |
682 | return NULL; | |
7368a6c8 | 683 | } |
684 | ||
1853d1ef | 685 | Key * |
686 | get_hostkey_by_index(int ind) | |
687 | { | |
688 | if (ind < 0 || ind >= options.num_host_key_files) | |
689 | return (NULL); | |
690 | return (sensitive_data.host_keys[ind]); | |
691 | } | |
692 | ||
693 | int | |
694 | get_hostkey_index(Key *key) | |
695 | { | |
696 | int i; | |
697 | for (i = 0; i < options.num_host_key_files; i++) { | |
698 | if (key == sensitive_data.host_keys[i]) | |
699 | return (i); | |
700 | } | |
701 | return (-1); | |
702 | } | |
703 | ||
c345cf9d | 704 | /* |
705 | * returns 1 if connection should be dropped, 0 otherwise. | |
706 | * dropping starts at connection #max_startups_begin with a probability | |
707 | * of (max_startups_rate/100). the probability increases linearly until | |
708 | * all connections are dropped for startups > max_startups | |
709 | */ | |
396c147e | 710 | static int |
c345cf9d | 711 | drop_connection(int startups) |
712 | { | |
713 | double p, r; | |
714 | ||
715 | if (startups < options.max_startups_begin) | |
716 | return 0; | |
717 | if (startups >= options.max_startups) | |
718 | return 1; | |
719 | if (options.max_startups_rate == 100) | |
720 | return 1; | |
721 | ||
722 | p = 100 - options.max_startups_rate; | |
723 | p *= startups - options.max_startups_begin; | |
724 | p /= (double) (options.max_startups - options.max_startups_begin); | |
725 | p += options.max_startups_rate; | |
726 | p /= 100.0; | |
727 | r = arc4random() / (double) UINT_MAX; | |
728 | ||
729 | debug("drop_connection: p %g, r %g", p, r); | |
730 | return (r < p) ? 1 : 0; | |
731 | } | |
732 | ||
2717fa0f | 733 | static void |
734 | usage(void) | |
735 | { | |
736 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
737 | fprintf(stderr, "Usage: %s [options]\n", __progname); | |
738 | fprintf(stderr, "Options:\n"); | |
739 | fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE); | |
740 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); | |
741 | fprintf(stderr, " -i Started from inetd\n"); | |
742 | fprintf(stderr, " -D Do not fork into daemon mode\n"); | |
743 | fprintf(stderr, " -t Only test configuration file and keys\n"); | |
744 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
745 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
746 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
747 | fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n"); | |
748 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
749 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
750 | _PATH_HOST_KEY_FILE); | |
751 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); | |
752 | fprintf(stderr, " -4 Use IPv4 only\n"); | |
753 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
754 | fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n"); | |
755 | exit(1); | |
756 | } | |
757 | ||
5260325f | 758 | /* |
759 | * Main program for the daemon. | |
760 | */ | |
8efc0c15 | 761 | int |
762 | main(int ac, char **av) | |
763 | { | |
5260325f | 764 | extern char *optarg; |
765 | extern int optind; | |
089fbbd2 | 766 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; |
9da5c3c9 | 767 | pid_t pid; |
48e671d5 | 768 | socklen_t fromlen; |
48e671d5 | 769 | fd_set *fdset; |
770 | struct sockaddr_storage from; | |
5260325f | 771 | const char *remote_ip; |
772 | int remote_port; | |
5260325f | 773 | FILE *f; |
774 | struct linger linger; | |
48e671d5 | 775 | struct addrinfo *ai; |
776 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
777 | int listen_sock, maxfd; | |
089fbbd2 | 778 | int startup_p[2]; |
779 | int startups = 0; | |
1b34c1b3 | 780 | Authctxt *authctxt; |
aeaa3d9e | 781 | Key *key; |
59c97189 | 782 | int ret, key_used = 0; |
5260325f | 783 | |
260d427b | 784 | __progname = get_progname(av[0]); |
264dce47 | 785 | init_rng(); |
786 | ||
1fe6a48f | 787 | /* Save argv. */ |
4d33e531 | 788 | saved_argc = ac; |
5260325f | 789 | saved_argv = av; |
5260325f | 790 | |
791 | /* Initialize configuration options to their default values. */ | |
792 | initialize_server_options(&options); | |
793 | ||
794 | /* Parse command-line arguments. */ | |
2717fa0f | 795 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) { |
5260325f | 796 | switch (opt) { |
48e671d5 | 797 | case '4': |
798 | IPv4or6 = AF_INET; | |
799 | break; | |
800 | case '6': | |
801 | IPv4or6 = AF_INET6; | |
802 | break; | |
5260325f | 803 | case 'f': |
804 | config_file_name = optarg; | |
805 | break; | |
806 | case 'd': | |
bcbf86ec | 807 | if (0 == debug_flag) { |
808 | debug_flag = 1; | |
809 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
810 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
811 | options.log_level++; | |
812 | } else { | |
813 | fprintf(stderr, "Too high debugging level.\n"); | |
814 | exit(1); | |
815 | } | |
5260325f | 816 | break; |
0b6fbf03 | 817 | case 'D': |
818 | no_daemon_flag = 1; | |
819 | break; | |
ff14faf1 | 820 | case 'e': |
821 | log_stderr = 1; | |
822 | break; | |
5260325f | 823 | case 'i': |
824 | inetd_flag = 1; | |
825 | break; | |
826 | case 'Q': | |
9bd5b720 | 827 | /* ignored */ |
5260325f | 828 | break; |
829 | case 'q': | |
830 | options.log_level = SYSLOG_LEVEL_QUIET; | |
831 | break; | |
832 | case 'b': | |
833 | options.server_key_bits = atoi(optarg); | |
834 | break; | |
835 | case 'p': | |
48e671d5 | 836 | options.ports_from_cmdline = 1; |
bcbf86ec | 837 | if (options.num_ports >= MAX_PORTS) { |
838 | fprintf(stderr, "too many ports.\n"); | |
839 | exit(1); | |
840 | } | |
2d2a2c65 | 841 | options.ports[options.num_ports++] = a2port(optarg); |
842 | if (options.ports[options.num_ports-1] == 0) { | |
843 | fprintf(stderr, "Bad port number.\n"); | |
844 | exit(1); | |
845 | } | |
5260325f | 846 | break; |
847 | case 'g': | |
e2b1fb42 | 848 | if ((options.login_grace_time = convtime(optarg)) == -1) { |
849 | fprintf(stderr, "Invalid login grace time.\n"); | |
850 | exit(1); | |
851 | } | |
5260325f | 852 | break; |
853 | case 'k': | |
e2b1fb42 | 854 | if ((options.key_regeneration_time = convtime(optarg)) == -1) { |
855 | fprintf(stderr, "Invalid key regeneration interval.\n"); | |
856 | exit(1); | |
857 | } | |
5260325f | 858 | break; |
859 | case 'h': | |
fa08c86b | 860 | if (options.num_host_key_files >= MAX_HOSTKEYS) { |
861 | fprintf(stderr, "too many host keys.\n"); | |
862 | exit(1); | |
863 | } | |
864 | options.host_key_files[options.num_host_key_files++] = optarg; | |
5260325f | 865 | break; |
866 | case 'V': | |
867 | client_version_string = optarg; | |
868 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
869 | inetd_flag = 1; | |
870 | break; | |
f87f09aa | 871 | case 't': |
872 | test_flag = 1; | |
873 | break; | |
c345cf9d | 874 | case 'u': |
875 | utmp_len = atoi(optarg); | |
876 | break; | |
2717fa0f | 877 | case 'o': |
184eed6a | 878 | if (process_server_config_line(&options, optarg, |
2717fa0f | 879 | "command-line", 0) != 0) |
184eed6a | 880 | exit(1); |
2717fa0f | 881 | break; |
5260325f | 882 | case '?': |
883 | default: | |
2717fa0f | 884 | usage(); |
885 | break; | |
5260325f | 886 | } |
887 | } | |
1a92bd7e | 888 | SSLeay_add_all_algorithms(); |
5e4a7219 | 889 | channel_set_af(IPv4or6); |
5260325f | 890 | |
48e671d5 | 891 | /* |
892 | * Force logging to stderr until we have loaded the private host | |
893 | * key (unless started from inetd) | |
894 | */ | |
1fe6a48f | 895 | log_init(__progname, |
980c9344 | 896 | options.log_level == SYSLOG_LEVEL_NOT_SET ? |
897 | SYSLOG_LEVEL_INFO : options.log_level, | |
898 | options.log_facility == SYSLOG_FACILITY_NOT_SET ? | |
899 | SYSLOG_FACILITY_AUTH : options.log_facility, | |
9bd5b720 | 900 | !inetd_flag); |
48e671d5 | 901 | |
1a23ac2c | 902 | #ifdef _CRAY |
903 | /* Cray can define user privs drop all prives now! | |
904 | * Not needed on PRIV_SU systems! | |
905 | */ | |
906 | drop_cray_privs(); | |
907 | #endif | |
908 | ||
e339aa53 | 909 | seed_rng(); |
910 | ||
5260325f | 911 | /* Read server configuration options from the configuration file. */ |
912 | read_server_config(&options, config_file_name); | |
913 | ||
914 | /* Fill in default values for those options not explicitly set. */ | |
915 | fill_default_server_options(&options); | |
916 | ||
5260325f | 917 | /* Check that there are no remaining arguments. */ |
918 | if (optind < ac) { | |
919 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
920 | exit(1); | |
8efc0c15 | 921 | } |
5260325f | 922 | |
923 | debug("sshd version %.100s", SSH_VERSION); | |
924 | ||
fa08c86b | 925 | /* load private host keys */ |
926 | sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*)); | |
184eed6a | 927 | for (i = 0; i < options.num_host_key_files; i++) |
1e3b8b07 | 928 | sensitive_data.host_keys[i] = NULL; |
fa08c86b | 929 | sensitive_data.server_key = NULL; |
930 | sensitive_data.ssh1_host_key = NULL; | |
931 | sensitive_data.have_ssh1_key = 0; | |
932 | sensitive_data.have_ssh2_key = 0; | |
a306f2dd | 933 | |
184eed6a | 934 | for (i = 0; i < options.num_host_key_files; i++) { |
aeaa3d9e | 935 | key = key_load_private(options.host_key_files[i], "", NULL); |
936 | sensitive_data.host_keys[i] = key; | |
fa08c86b | 937 | if (key == NULL) { |
58cfa257 | 938 | error("Could not load host key: %s", |
939 | options.host_key_files[i]); | |
aeaa3d9e | 940 | sensitive_data.host_keys[i] = NULL; |
fa08c86b | 941 | continue; |
a306f2dd | 942 | } |
6aacefa7 | 943 | switch (key->type) { |
fa08c86b | 944 | case KEY_RSA1: |
945 | sensitive_data.ssh1_host_key = key; | |
946 | sensitive_data.have_ssh1_key = 1; | |
947 | break; | |
948 | case KEY_RSA: | |
949 | case KEY_DSA: | |
950 | sensitive_data.have_ssh2_key = 1; | |
951 | break; | |
a306f2dd | 952 | } |
aeaa3d9e | 953 | debug("private host key: #%d type %d %s", i, key->type, |
954 | key_type(key)); | |
fa08c86b | 955 | } |
956 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
957 | log("Disabling protocol version 1. Could not load host key"); | |
958 | options.protocol &= ~SSH_PROTO_1; | |
959 | } | |
960 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
961 | log("Disabling protocol version 2. Could not load host key"); | |
962 | options.protocol &= ~SSH_PROTO_2; | |
a306f2dd | 963 | } |
6a416424 | 964 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { |
54b974dc | 965 | log("sshd: no hostkeys available -- exiting."); |
5260325f | 966 | exit(1); |
967 | } | |
5260325f | 968 | |
a306f2dd | 969 | /* Check certain values for sanity. */ |
970 | if (options.protocol & SSH_PROTO_1) { | |
971 | if (options.server_key_bits < 512 || | |
972 | options.server_key_bits > 32768) { | |
973 | fprintf(stderr, "Bad server key size.\n"); | |
974 | exit(1); | |
975 | } | |
976 | /* | |
977 | * Check that server and host key lengths differ sufficiently. This | |
978 | * is necessary to make double encryption work with rsaref. Oh, I | |
979 | * hate software patents. I dont know if this can go? Niels | |
980 | */ | |
981 | if (options.server_key_bits > | |
fa08c86b | 982 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED && |
a306f2dd | 983 | options.server_key_bits < |
fa08c86b | 984 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { |
a306f2dd | 985 | options.server_key_bits = |
fa08c86b | 986 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED; |
a306f2dd | 987 | debug("Forcing server key to %d bits to make it differ from host key.", |
988 | options.server_key_bits); | |
989 | } | |
990 | } | |
991 | ||
f87f09aa | 992 | /* Configuration looks good, so exit if in test mode. */ |
993 | if (test_flag) | |
994 | exit(0); | |
995 | ||
77bb0bca | 996 | #ifdef HAVE_SCO_PROTECTED_PW |
997 | (void) set_auth_parameters(ac, av); | |
998 | #endif | |
999 | ||
a306f2dd | 1000 | /* Initialize the log (it is reinitialized below in case we forked). */ |
5260325f | 1001 | if (debug_flag && !inetd_flag) |
1002 | log_stderr = 1; | |
1fe6a48f | 1003 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 1004 | |
a306f2dd | 1005 | /* |
1006 | * If not in debugging mode, and not started from inetd, disconnect | |
1007 | * from the controlling terminal, and fork. The original process | |
1008 | * exits. | |
1009 | */ | |
0b6fbf03 | 1010 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { |
8efc0c15 | 1011 | #ifdef TIOCNOTTY |
5260325f | 1012 | int fd; |
8efc0c15 | 1013 | #endif /* TIOCNOTTY */ |
5260325f | 1014 | if (daemon(0, 0) < 0) |
1015 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1016 | ||
1017 | /* Disconnect from the controlling tty. */ | |
8efc0c15 | 1018 | #ifdef TIOCNOTTY |
5ca51e19 | 1019 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); |
5260325f | 1020 | if (fd >= 0) { |
1021 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
1022 | close(fd); | |
1023 | } | |
8efc0c15 | 1024 | #endif /* TIOCNOTTY */ |
8efc0c15 | 1025 | } |
5260325f | 1026 | /* Reinitialize the log (because of the fork above). */ |
1fe6a48f | 1027 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 1028 | |
5260325f | 1029 | /* Initialize the random number generator. */ |
1030 | arc4random_stir(); | |
1031 | ||
1032 | /* Chdir to the root directory so that the current disk can be | |
1033 | unmounted if desired. */ | |
1034 | chdir("/"); | |
184eed6a | 1035 | |
1d3c30db | 1036 | /* ignore SIGPIPE */ |
1037 | signal(SIGPIPE, SIG_IGN); | |
5260325f | 1038 | |
5260325f | 1039 | /* Start listening for a socket, unless started from inetd. */ |
1040 | if (inetd_flag) { | |
ec1f12d3 | 1041 | int s1; |
5260325f | 1042 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ |
ec1f12d3 | 1043 | dup(s1); |
5260325f | 1044 | sock_in = dup(0); |
1045 | sock_out = dup(1); | |
4c8722d9 | 1046 | startup_pipe = -1; |
a306f2dd | 1047 | /* |
1048 | * We intentionally do not close the descriptors 0, 1, and 2 | |
1049 | * as our code for setting the descriptors won\'t work if | |
1050 | * ttyfd happens to be one of those. | |
1051 | */ | |
5260325f | 1052 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); |
fa08c86b | 1053 | if (options.protocol & SSH_PROTO_1) |
cb7bd922 | 1054 | generate_ephemeral_server_key(); |
5260325f | 1055 | } else { |
48e671d5 | 1056 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
1057 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
1058 | continue; | |
1059 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
1060 | fatal("Too many listen sockets. " | |
1061 | "Enlarge MAX_LISTEN_SOCKS"); | |
1062 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
1063 | ntop, sizeof(ntop), strport, sizeof(strport), | |
1064 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
1065 | error("getnameinfo failed"); | |
1066 | continue; | |
1067 | } | |
1068 | /* Create socket for listening. */ | |
1069 | listen_sock = socket(ai->ai_family, SOCK_STREAM, 0); | |
1070 | if (listen_sock < 0) { | |
1071 | /* kernel may not support ipv6 */ | |
1072 | verbose("socket: %.100s", strerror(errno)); | |
1073 | continue; | |
1074 | } | |
1075 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
1076 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
1077 | close(listen_sock); | |
1078 | continue; | |
1079 | } | |
1080 | /* | |
1081 | * Set socket options. We try to make the port | |
1082 | * reusable and have it close as fast as possible | |
1083 | * without waiting in unnecessary wait states on | |
1084 | * close. | |
1085 | */ | |
1086 | setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, | |
db518d9b | 1087 | &on, sizeof(on)); |
48e671d5 | 1088 | linger.l_onoff = 1; |
1089 | linger.l_linger = 5; | |
1090 | setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, | |
db518d9b | 1091 | &linger, sizeof(linger)); |
48e671d5 | 1092 | |
1093 | debug("Bind to port %s on %s.", strport, ntop); | |
1094 | ||
1095 | /* Bind the socket to the desired port. */ | |
32ced054 | 1096 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { |
1097 | if (!ai->ai_next) | |
1098 | error("Bind to port %s on %s failed: %.200s.", | |
1099 | strport, ntop, strerror(errno)); | |
48e671d5 | 1100 | close(listen_sock); |
1101 | continue; | |
1102 | } | |
1103 | listen_socks[num_listen_socks] = listen_sock; | |
1104 | num_listen_socks++; | |
1105 | ||
1106 | /* Start listening on the port. */ | |
1107 | log("Server listening on %s port %s.", ntop, strport); | |
1108 | if (listen(listen_sock, 5) < 0) | |
1109 | fatal("listen: %.100s", strerror(errno)); | |
1110 | ||
5260325f | 1111 | } |
48e671d5 | 1112 | freeaddrinfo(options.listen_addrs); |
1113 | ||
1114 | if (!num_listen_socks) | |
1115 | fatal("Cannot bind any address."); | |
1116 | ||
3aca00a3 | 1117 | if (options.protocol & SSH_PROTO_1) |
1118 | generate_ephemeral_server_key(); | |
1119 | ||
1120 | /* | |
1121 | * Arrange to restart on SIGHUP. The handler needs | |
1122 | * listen_sock. | |
1123 | */ | |
1124 | signal(SIGHUP, sighup_handler); | |
1125 | ||
1126 | signal(SIGTERM, sigterm_handler); | |
1127 | signal(SIGQUIT, sigterm_handler); | |
1128 | ||
1129 | /* Arrange SIGCHLD to be caught. */ | |
1130 | signal(SIGCHLD, main_sigchld_handler); | |
1131 | ||
1132 | /* Write out the pid file after the sigterm handler is setup */ | |
5260325f | 1133 | if (!debug_flag) { |
aa3378df | 1134 | /* |
97fb6912 | 1135 | * Record our pid in /var/run/sshd.pid to make it |
1136 | * easier to kill the correct sshd. We don't want to | |
1137 | * do this before the bind above because the bind will | |
aa3378df | 1138 | * fail if there already is a daemon, and this will |
1139 | * overwrite any old pid in the file. | |
1140 | */ | |
3c62e7eb | 1141 | f = fopen(options.pid_file, "wb"); |
5260325f | 1142 | if (f) { |
1e3b8b07 | 1143 | fprintf(f, "%u\n", (u_int) getpid()); |
5260325f | 1144 | fclose(f); |
1145 | } | |
8efc0c15 | 1146 | } |
5260325f | 1147 | |
48e671d5 | 1148 | /* setup fd set for listen */ |
089fbbd2 | 1149 | fdset = NULL; |
48e671d5 | 1150 | maxfd = 0; |
1151 | for (i = 0; i < num_listen_socks; i++) | |
1152 | if (listen_socks[i] > maxfd) | |
1153 | maxfd = listen_socks[i]; | |
089fbbd2 | 1154 | /* pipes connected to unauthenticated childs */ |
1155 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
1156 | for (i = 0; i < options.max_startups; i++) | |
1157 | startup_pipes[i] = -1; | |
48e671d5 | 1158 | |
aa3378df | 1159 | /* |
1160 | * Stay listening for connections until the system crashes or | |
1161 | * the daemon is killed with a signal. | |
1162 | */ | |
5260325f | 1163 | for (;;) { |
1164 | if (received_sighup) | |
1165 | sighup_restart(); | |
089fbbd2 | 1166 | if (fdset != NULL) |
1167 | xfree(fdset); | |
b5c334cc | 1168 | fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); |
089fbbd2 | 1169 | fdset = (fd_set *)xmalloc(fdsetsz); |
48e671d5 | 1170 | memset(fdset, 0, fdsetsz); |
089fbbd2 | 1171 | |
48e671d5 | 1172 | for (i = 0; i < num_listen_socks; i++) |
1173 | FD_SET(listen_socks[i], fdset); | |
089fbbd2 | 1174 | for (i = 0; i < options.max_startups; i++) |
1175 | if (startup_pipes[i] != -1) | |
1176 | FD_SET(startup_pipes[i], fdset); | |
1177 | ||
1178 | /* Wait in select until there is a connection. */ | |
59c97189 | 1179 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); |
1180 | if (ret < 0 && errno != EINTR) | |
1181 | error("select: %.100s", strerror(errno)); | |
c9130033 | 1182 | if (received_sigterm) { |
1183 | log("Received signal %d; terminating.", | |
010f9726 | 1184 | (int) received_sigterm); |
c9130033 | 1185 | close_listen_socks(); |
1186 | unlink(options.pid_file); | |
1187 | exit(255); | |
1188 | } | |
59c97189 | 1189 | if (key_used && key_do_regen) { |
cb7bd922 | 1190 | generate_ephemeral_server_key(); |
59c97189 | 1191 | key_used = 0; |
1192 | key_do_regen = 0; | |
48e671d5 | 1193 | } |
59c97189 | 1194 | if (ret < 0) |
1195 | continue; | |
1196 | ||
089fbbd2 | 1197 | for (i = 0; i < options.max_startups; i++) |
1198 | if (startup_pipes[i] != -1 && | |
1199 | FD_ISSET(startup_pipes[i], fdset)) { | |
1200 | /* | |
1201 | * the read end of the pipe is ready | |
1202 | * if the child has closed the pipe | |
8abcdba4 | 1203 | * after successful authentication |
089fbbd2 | 1204 | * or if the child has died |
1205 | */ | |
1206 | close(startup_pipes[i]); | |
1207 | startup_pipes[i] = -1; | |
1208 | startups--; | |
1209 | } | |
48e671d5 | 1210 | for (i = 0; i < num_listen_socks; i++) { |
1211 | if (!FD_ISSET(listen_socks[i], fdset)) | |
5260325f | 1212 | continue; |
089fbbd2 | 1213 | fromlen = sizeof(from); |
1214 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
1215 | &fromlen); | |
1216 | if (newsock < 0) { | |
1217 | if (errno != EINTR && errno != EWOULDBLOCK) | |
1218 | error("accept: %.100s", strerror(errno)); | |
1219 | continue; | |
1220 | } | |
1221 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
1222 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
5e8948af | 1223 | close(newsock); |
089fbbd2 | 1224 | continue; |
1225 | } | |
c345cf9d | 1226 | if (drop_connection(startups) == 1) { |
1227 | debug("drop connection #%d", startups); | |
089fbbd2 | 1228 | close(newsock); |
1229 | continue; | |
1230 | } | |
1231 | if (pipe(startup_p) == -1) { | |
1232 | close(newsock); | |
1233 | continue; | |
1234 | } | |
1235 | ||
1236 | for (j = 0; j < options.max_startups; j++) | |
1237 | if (startup_pipes[j] == -1) { | |
1238 | startup_pipes[j] = startup_p[0]; | |
1239 | if (maxfd < startup_p[0]) | |
1240 | maxfd = startup_p[0]; | |
1241 | startups++; | |
1242 | break; | |
1243 | } | |
2b87da3b | 1244 | |
aa3378df | 1245 | /* |
089fbbd2 | 1246 | * Got connection. Fork a child to handle it, unless |
1247 | * we are in debugging mode. | |
aa3378df | 1248 | */ |
089fbbd2 | 1249 | if (debug_flag) { |
aa3378df | 1250 | /* |
089fbbd2 | 1251 | * In debugging mode. Close the listening |
1252 | * socket, and start processing the | |
1253 | * connection without forking. | |
aa3378df | 1254 | */ |
089fbbd2 | 1255 | debug("Server will not fork when running in debugging mode."); |
48e671d5 | 1256 | close_listen_socks(); |
5260325f | 1257 | sock_in = newsock; |
1258 | sock_out = newsock; | |
5540ea9b | 1259 | startup_pipe = -1; |
3f7a7e4a | 1260 | pid = getpid(); |
5260325f | 1261 | break; |
089fbbd2 | 1262 | } else { |
1263 | /* | |
1264 | * Normal production daemon. Fork, and have | |
1265 | * the child process the connection. The | |
1266 | * parent continues listening. | |
1267 | */ | |
1268 | if ((pid = fork()) == 0) { | |
1269 | /* | |
1270 | * Child. Close the listening and max_startup | |
1271 | * sockets. Start using the accepted socket. | |
1272 | * Reinitialize logging (since our pid has | |
1273 | * changed). We break out of the loop to handle | |
1274 | * the connection. | |
1275 | */ | |
1276 | startup_pipe = startup_p[1]; | |
7ace8c3b | 1277 | close_startup_pipes(); |
089fbbd2 | 1278 | close_listen_socks(); |
1279 | sock_in = newsock; | |
1280 | sock_out = newsock; | |
1fe6a48f | 1281 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
089fbbd2 | 1282 | break; |
1283 | } | |
5260325f | 1284 | } |
5260325f | 1285 | |
089fbbd2 | 1286 | /* Parent. Stay in the loop. */ |
1287 | if (pid < 0) | |
1288 | error("fork: %.100s", strerror(errno)); | |
1289 | else | |
1290 | debug("Forked child %d.", pid); | |
5260325f | 1291 | |
089fbbd2 | 1292 | close(startup_p[1]); |
5260325f | 1293 | |
089fbbd2 | 1294 | /* Mark that the key has been used (it was "given" to the child). */ |
59c97189 | 1295 | if ((options.protocol & SSH_PROTO_1) && |
1296 | key_used == 0) { | |
1297 | /* Schedule server key regeneration alarm. */ | |
1298 | signal(SIGALRM, key_regeneration_alarm); | |
1299 | alarm(options.key_regeneration_time); | |
1300 | key_used = 1; | |
1301 | } | |
5260325f | 1302 | |
089fbbd2 | 1303 | arc4random_stir(); |
1304 | ||
1305 | /* Close the new socket (the child is now taking care of it). */ | |
1306 | close(newsock); | |
1307 | } | |
48e671d5 | 1308 | /* child process check (or debug mode) */ |
1309 | if (num_listen_socks < 0) | |
1310 | break; | |
5260325f | 1311 | } |
1312 | } | |
8efc0c15 | 1313 | |
5260325f | 1314 | /* This is the child processing a new connection. */ |
1315 | ||
aa3378df | 1316 | /* |
1317 | * Disable the key regeneration alarm. We will not regenerate the | |
1318 | * key since we are no longer in a position to give it to anyone. We | |
1319 | * will not restart on SIGHUP since it no longer makes sense. | |
1320 | */ | |
5260325f | 1321 | alarm(0); |
1322 | signal(SIGALRM, SIG_DFL); | |
1323 | signal(SIGHUP, SIG_DFL); | |
1324 | signal(SIGTERM, SIG_DFL); | |
1325 | signal(SIGQUIT, SIG_DFL); | |
1326 | signal(SIGCHLD, SIG_DFL); | |
9aaf9be4 | 1327 | signal(SIGINT, SIG_DFL); |
5260325f | 1328 | |
aa3378df | 1329 | /* |
1330 | * Set socket options for the connection. We want the socket to | |
1331 | * close as fast as possible without waiting for anything. If the | |
1332 | * connection is not a socket, these will do nothing. | |
1333 | */ | |
1334 | /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 1335 | linger.l_onoff = 1; |
1336 | linger.l_linger = 5; | |
db518d9b | 1337 | setsockopt(sock_in, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger)); |
5260325f | 1338 | |
b5c334cc | 1339 | /* Set keepalives if requested. */ |
1340 | if (options.keepalives && | |
db518d9b | 1341 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, |
b5c334cc | 1342 | sizeof(on)) < 0) |
1343 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1344 | ||
aa3378df | 1345 | /* |
1346 | * Register our connection. This turns encryption off because we do | |
1347 | * not have a key. | |
1348 | */ | |
5260325f | 1349 | packet_set_connection(sock_in, sock_out); |
1350 | ||
1351 | remote_port = get_remote_port(); | |
1352 | remote_ip = get_remote_ipaddr(); | |
1353 | ||
5260325f | 1354 | #ifdef LIBWRAP |
ac28afd8 | 1355 | /* Check whether logins are denied from this host. */ |
5260325f | 1356 | { |
1357 | struct request_info req; | |
8efc0c15 | 1358 | |
8fbc356d | 1359 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); |
5260325f | 1360 | fromhost(&req); |
8efc0c15 | 1361 | |
5260325f | 1362 | if (!hosts_access(&req)) { |
ac28afd8 | 1363 | debug("Connection refused by tcp wrapper"); |
563834bb | 1364 | refuse(&req); |
ac28afd8 | 1365 | /* NOTREACHED */ |
1366 | fatal("libwrap refuse returns"); | |
5260325f | 1367 | } |
8efc0c15 | 1368 | } |
48e671d5 | 1369 | #endif /* LIBWRAP */ |
ac28afd8 | 1370 | |
5260325f | 1371 | /* Log the connection. */ |
1372 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
8efc0c15 | 1373 | |
aa3378df | 1374 | /* |
1375 | * We don\'t want to listen forever unless the other side | |
1376 | * successfully authenticates itself. So we set up an alarm which is | |
1377 | * cleared after successful authentication. A limit of zero | |
1378 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1379 | * mode; it is just annoying to have the server exit just when you | |
1380 | * are about to discover the bug. | |
1381 | */ | |
5260325f | 1382 | signal(SIGALRM, grace_alarm_handler); |
1383 | if (!debug_flag) | |
1384 | alarm(options.login_grace_time); | |
1385 | ||
7368a6c8 | 1386 | sshd_exchange_identification(sock_in, sock_out); |
aa3378df | 1387 | /* |
6ffc9c88 | 1388 | * Check that the connection comes from a privileged port. |
1389 | * Rhosts-Authentication only makes sense from priviledged | |
aa3378df | 1390 | * programs. Of course, if the intruder has root access on his local |
1391 | * machine, he can connect from any port. So do not use these | |
1392 | * authentication methods from machines that you do not trust. | |
1393 | */ | |
44b1a8e5 | 1394 | if (options.rhosts_authentication && |
1395 | (remote_port >= IPPORT_RESERVED || | |
1396 | remote_port < IPPORT_RESERVED / 2)) { | |
6ffc9c88 | 1397 | debug("Rhosts Authentication disabled, " |
9ae3f727 | 1398 | "originating port %d not trusted.", remote_port); |
5260325f | 1399 | options.rhosts_authentication = 0; |
5260325f | 1400 | } |
ced49be2 | 1401 | #if defined(KRB4) && !defined(KRB5) |
48e671d5 | 1402 | if (!packet_connection_is_ipv4() && |
1403 | options.kerberos_authentication) { | |
1404 | debug("Kerberos Authentication disabled, only available for IPv4."); | |
1405 | options.kerberos_authentication = 0; | |
1406 | } | |
ced49be2 | 1407 | #endif /* KRB4 && !KRB5 */ |
abf1f107 | 1408 | #ifdef AFS |
1409 | /* If machine has AFS, set process authentication group. */ | |
1410 | if (k_hasafs()) { | |
1411 | k_setpag(); | |
1412 | k_unlog(); | |
1413 | } | |
1414 | #endif /* AFS */ | |
48e671d5 | 1415 | |
5260325f | 1416 | packet_set_nonblocking(); |
1417 | ||
324bf712 | 1418 | if (use_privsep) |
1419 | if ((authctxt = privsep_preauth()) != NULL) | |
1420 | goto authenticated; | |
1853d1ef | 1421 | |
7b2ea3a1 | 1422 | /* perform the key exchange */ |
7b2ea3a1 | 1423 | /* authenticate user and start session */ |
e78a59f5 | 1424 | if (compat20) { |
1425 | do_ssh2_kex(); | |
1b34c1b3 | 1426 | authctxt = do_authentication2(); |
e78a59f5 | 1427 | } else { |
1428 | do_ssh1_kex(); | |
1b34c1b3 | 1429 | authctxt = do_authentication(); |
e78a59f5 | 1430 | } |
324bf712 | 1431 | /* |
1432 | * If we use privilege separation, the unprivileged child transfers | |
1433 | * the current keystate and exits | |
1434 | */ | |
1435 | if (use_privsep) { | |
1853d1ef | 1436 | mm_send_keystate(monitor); |
1853d1ef | 1437 | exit(0); |
324bf712 | 1438 | } |
1853d1ef | 1439 | |
1440 | authenticated: | |
762715ce | 1441 | /* |
1853d1ef | 1442 | * In privilege separation, we fork another child and prepare |
1443 | * file descriptor passing. | |
1444 | */ | |
1445 | if (use_privsep) { | |
324bf712 | 1446 | privsep_postauth(authctxt); |
1447 | /* the monitor process [priv] will not return */ | |
1853d1ef | 1448 | if (!compat20) |
1449 | destroy_sensitive_data(); | |
1450 | } | |
1b34c1b3 | 1451 | |
1452 | /* Perform session preparation. */ | |
1453 | do_authenticated(authctxt); | |
1454 | ||
63284fbb | 1455 | /* The connection has been terminated. */ |
1456 | verbose("Closing connection to %.100s", remote_ip); | |
8efc0c15 | 1457 | |
d94aa2ae | 1458 | #ifdef USE_PAM |
a5c9cd31 | 1459 | finish_pam(); |
d94aa2ae | 1460 | #endif /* USE_PAM */ |
8efc0c15 | 1461 | |
5260325f | 1462 | packet_close(); |
1853d1ef | 1463 | |
1464 | if (use_privsep) | |
1465 | mm_terminate(); | |
1466 | ||
5260325f | 1467 | exit(0); |
1468 | } | |
8efc0c15 | 1469 | |
4f08e98d | 1470 | /* |
1471 | * Decrypt session_key_int using our private server key and private host key | |
1472 | * (key with larger modulus first). | |
1473 | */ | |
1853d1ef | 1474 | int |
4f08e98d | 1475 | ssh1_session_key(BIGNUM *session_key_int) |
1476 | { | |
1477 | int rsafail = 0; | |
1478 | ||
1479 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { | |
1480 | /* Server key has bigger modulus. */ | |
1481 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < | |
1482 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1483 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1484 | get_remote_ipaddr(), | |
1485 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1486 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1487 | SSH_KEY_BITS_RESERVED); | |
1488 | } | |
1489 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1490 | sensitive_data.server_key->rsa) <= 0) | |
1491 | rsafail++; | |
1492 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1493 | sensitive_data.ssh1_host_key->rsa) <= 0) | |
1494 | rsafail++; | |
1495 | } else { | |
1496 | /* Host key has bigger modulus (or they are equal). */ | |
1497 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < | |
1498 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1499 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1500 | get_remote_ipaddr(), | |
1501 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1502 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1503 | SSH_KEY_BITS_RESERVED); | |
1504 | } | |
1505 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1506 | sensitive_data.ssh1_host_key->rsa) < 0) | |
1507 | rsafail++; | |
1508 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1509 | sensitive_data.server_key->rsa) < 0) | |
1510 | rsafail++; | |
1511 | } | |
1512 | return (rsafail); | |
1513 | } | |
5260325f | 1514 | /* |
7b2ea3a1 | 1515 | * SSH1 key exchange |
5260325f | 1516 | */ |
396c147e | 1517 | static void |
1e3b8b07 | 1518 | do_ssh1_kex(void) |
8efc0c15 | 1519 | { |
5260325f | 1520 | int i, len; |
46aa2d1f | 1521 | int rsafail = 0; |
5260325f | 1522 | BIGNUM *session_key_int; |
1e3b8b07 | 1523 | u_char session_key[SSH_SESSION_KEY_LENGTH]; |
1524 | u_char cookie[8]; | |
1525 | u_int cipher_type, auth_mask, protocol_flags; | |
5260325f | 1526 | u_int32_t rand = 0; |
1527 | ||
aa3378df | 1528 | /* |
1529 | * Generate check bytes that the client must send back in the user | |
1530 | * packet in order for it to be accepted; this is used to defy ip | |
1531 | * spoofing attacks. Note that this only works against somebody | |
1532 | * doing IP spoofing from a remote machine; any machine on the local | |
1533 | * network can still see outgoing packets and catch the random | |
1534 | * cookie. This only affects rhosts authentication, and this is one | |
1535 | * of the reasons why it is inherently insecure. | |
1536 | */ | |
5260325f | 1537 | for (i = 0; i < 8; i++) { |
1538 | if (i % 4 == 0) | |
1539 | rand = arc4random(); | |
7b2ea3a1 | 1540 | cookie[i] = rand & 0xff; |
5260325f | 1541 | rand >>= 8; |
1542 | } | |
1543 | ||
aa3378df | 1544 | /* |
1545 | * Send our public key. We include in the packet 64 bits of random | |
1546 | * data that must be matched in the reply in order to prevent IP | |
1547 | * spoofing. | |
1548 | */ | |
5260325f | 1549 | packet_start(SSH_SMSG_PUBLIC_KEY); |
1550 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1551 | packet_put_char(cookie[i]); |
5260325f | 1552 | |
1553 | /* Store our public server RSA key. */ | |
fa08c86b | 1554 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); |
1555 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1556 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
5260325f | 1557 | |
1558 | /* Store our public host RSA key. */ | |
fa08c86b | 1559 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); |
1560 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1561 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
5260325f | 1562 | |
1563 | /* Put protocol flags. */ | |
1564 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1565 | ||
1566 | /* Declare which ciphers we support. */ | |
94ec8c6b | 1567 | packet_put_int(cipher_mask_ssh1(0)); |
5260325f | 1568 | |
1569 | /* Declare supported authentication types. */ | |
1570 | auth_mask = 0; | |
1571 | if (options.rhosts_authentication) | |
1572 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
1573 | if (options.rhosts_rsa_authentication) | |
1574 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1575 | if (options.rsa_authentication) | |
1576 | auth_mask |= 1 << SSH_AUTH_RSA; | |
ced49be2 | 1577 | #if defined(KRB4) || defined(KRB5) |
5260325f | 1578 | if (options.kerberos_authentication) |
1579 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
8efc0c15 | 1580 | #endif |
ced49be2 | 1581 | #if defined(AFS) || defined(KRB5) |
5260325f | 1582 | if (options.kerberos_tgt_passing) |
1583 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
ced49be2 | 1584 | #endif |
1585 | #ifdef AFS | |
5260325f | 1586 | if (options.afs_token_passing) |
1587 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
8efc0c15 | 1588 | #endif |
5ba55ada | 1589 | if (options.challenge_response_authentication == 1) |
5260325f | 1590 | auth_mask |= 1 << SSH_AUTH_TIS; |
5260325f | 1591 | if (options.password_authentication) |
1592 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1593 | packet_put_int(auth_mask); | |
1594 | ||
1595 | /* Send the packet and wait for it to be sent. */ | |
1596 | packet_send(); | |
1597 | packet_write_wait(); | |
1598 | ||
fa08c86b | 1599 | debug("Sent %d bit server key and %d bit host key.", |
1600 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1601 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
5260325f | 1602 | |
1603 | /* Read clients reply (cipher type and session key). */ | |
54a5250f | 1604 | packet_read_expect(SSH_CMSG_SESSION_KEY); |
5260325f | 1605 | |
2d86a6cc | 1606 | /* Get cipher type and check whether we accept this. */ |
5260325f | 1607 | cipher_type = packet_get_char(); |
1608 | ||
94ec8c6b | 1609 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) |
2d86a6cc | 1610 | packet_disconnect("Warning: client selects unsupported cipher."); |
1611 | ||
5260325f | 1612 | /* Get check bytes from the packet. These must match those we |
1613 | sent earlier with the public key packet. */ | |
1614 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1615 | if (cookie[i] != packet_get_char()) |
5260325f | 1616 | packet_disconnect("IP Spoofing check bytes do not match."); |
1617 | ||
1618 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1619 | ||
1620 | /* Get the encrypted integer. */ | |
b775c6f2 | 1621 | if ((session_key_int = BN_new()) == NULL) |
1622 | fatal("do_ssh1_kex: BN_new failed"); | |
20b279e6 | 1623 | packet_get_bignum(session_key_int); |
5260325f | 1624 | |
5260325f | 1625 | protocol_flags = packet_get_int(); |
1626 | packet_set_protocol_flags(protocol_flags); | |
95500969 | 1627 | packet_check_eom(); |
5260325f | 1628 | |
4f08e98d | 1629 | /* Decrypt session_key_int using host/server keys */ |
1853d1ef | 1630 | rsafail = PRIVSEP(ssh1_session_key(session_key_int)); |
1631 | ||
aa3378df | 1632 | /* |
1633 | * Extract session key from the decrypted integer. The key is in the | |
1634 | * least significant 256 bits of the integer; the first byte of the | |
1635 | * key is in the highest bits. | |
1636 | */ | |
46aa2d1f | 1637 | if (!rsafail) { |
1638 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
1639 | len = BN_num_bytes(session_key_int); | |
1640 | if (len < 0 || len > sizeof(session_key)) { | |
1641 | error("do_connection: bad session key len from %s: " | |
5ca51e19 | 1642 | "session_key_int %d > sizeof(session_key) %lu", |
1643 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); | |
46aa2d1f | 1644 | rsafail++; |
1645 | } else { | |
1646 | memset(session_key, 0, sizeof(session_key)); | |
1647 | BN_bn2bin(session_key_int, | |
1648 | session_key + sizeof(session_key) - len); | |
00be5382 | 1649 | |
1650 | compute_session_id(session_id, cookie, | |
1651 | sensitive_data.ssh1_host_key->rsa->n, | |
1652 | sensitive_data.server_key->rsa->n); | |
1653 | /* | |
1654 | * Xor the first 16 bytes of the session key with the | |
1655 | * session id. | |
1656 | */ | |
1657 | for (i = 0; i < 16; i++) | |
1658 | session_key[i] ^= session_id[i]; | |
46aa2d1f | 1659 | } |
1660 | } | |
1661 | if (rsafail) { | |
00be5382 | 1662 | int bytes = BN_num_bytes(session_key_int); |
f6b1ba8f | 1663 | u_char *buf = xmalloc(bytes); |
00be5382 | 1664 | MD5_CTX md; |
1665 | ||
46aa2d1f | 1666 | log("do_connection: generating a fake encryption key"); |
00be5382 | 1667 | BN_bn2bin(session_key_int, buf); |
1668 | MD5_Init(&md); | |
1669 | MD5_Update(&md, buf, bytes); | |
1670 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1671 | MD5_Final(session_key, &md); | |
1672 | MD5_Init(&md); | |
1673 | MD5_Update(&md, session_key, 16); | |
1674 | MD5_Update(&md, buf, bytes); | |
1675 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1676 | MD5_Final(session_key + 16, &md); | |
1677 | memset(buf, 0, bytes); | |
1678 | xfree(buf); | |
0572fe75 | 1679 | for (i = 0; i < 16; i++) |
1680 | session_id[i] = session_key[i] ^ session_key[i + 16]; | |
46aa2d1f | 1681 | } |
1853d1ef | 1682 | /* Destroy the private and public keys. No longer. */ |
63284fbb | 1683 | destroy_sensitive_data(); |
00be5382 | 1684 | |
1853d1ef | 1685 | if (use_privsep) |
1686 | mm_ssh1_session_id(session_id); | |
1687 | ||
7b2ea3a1 | 1688 | /* Destroy the decrypted integer. It is no longer needed. */ |
1689 | BN_clear_free(session_key_int); | |
1690 | ||
5260325f | 1691 | /* Set the session key. From this on all communications will be encrypted. */ |
1692 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1693 | ||
1694 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1695 | memset(session_key, 0, sizeof(session_key)); | |
1696 | ||
1697 | debug("Received session key; encryption turned on."); | |
1698 | ||
1699 | /* Send an acknowledgement packet. Note that this packet is sent encrypted. */ | |
1700 | packet_start(SSH_SMSG_SUCCESS); | |
1701 | packet_send(); | |
1702 | packet_write_wait(); | |
5260325f | 1703 | } |
e78a59f5 | 1704 | |
1705 | /* | |
1706 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1707 | */ | |
396c147e | 1708 | static void |
1e3b8b07 | 1709 | do_ssh2_kex(void) |
e78a59f5 | 1710 | { |
e78a59f5 | 1711 | Kex *kex; |
e78a59f5 | 1712 | |
a8be9f80 | 1713 | if (options.ciphers != NULL) { |
6ae2364d | 1714 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
a8be9f80 | 1715 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
1716 | } | |
1ad64a93 | 1717 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
1718 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); | |
1719 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
1720 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); | |
1721 | ||
b2552997 | 1722 | if (options.macs != NULL) { |
1723 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
1724 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
1725 | } | |
fa08c86b | 1726 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
1727 | ||
7a37c112 | 1728 | /* start key exchange */ |
d8ee838b | 1729 | kex = kex_setup(myproposal); |
a5c9ffdb | 1730 | kex->server = 1; |
1731 | kex->client_version_string=client_version_string; | |
1732 | kex->server_version_string=server_version_string; | |
1733 | kex->load_host_key=&get_hostkey_by_type; | |
1853d1ef | 1734 | kex->host_key_index=&get_hostkey_index; |
94ec8c6b | 1735 | |
7a37c112 | 1736 | xxx_kex = kex; |
1737 | ||
c422989b | 1738 | dispatch_run(DISPATCH_BLOCK, &kex->done, kex); |
94ec8c6b | 1739 | |
d1ac6175 | 1740 | session_id2 = kex->session_id; |
1741 | session_id2_len = kex->session_id_len; | |
1742 | ||
94ec8c6b | 1743 | #ifdef DEBUG_KEXDH |
1744 | /* send 1st encrypted/maced/compressed message */ | |
1745 | packet_start(SSH2_MSG_IGNORE); | |
1746 | packet_put_cstring("markus"); | |
1747 | packet_send(); | |
1748 | packet_write_wait(); | |
1749 | #endif | |
a5c9ffdb | 1750 | debug("KEX done"); |
e78a59f5 | 1751 | } |