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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" | |
e424e241 | 45 | RCSID("$OpenBSD: sshd.c,v 1.250 2002/06/23 10:29:52 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 | */ | |
59e76f33 | 115 | #ifdef IPV4_DEFAULT |
116 | int IPv4or6 = AF_INET; | |
117 | #else | |
48e671d5 | 118 | int IPv4or6 = AF_UNSPEC; |
59e76f33 | 119 | #endif |
48e671d5 | 120 | |
5260325f | 121 | /* |
122 | * Debug mode flag. This can be set on the command line. If debug | |
123 | * mode is enabled, extra debugging output will be sent to the system | |
124 | * log, the daemon will not go to background, and will exit after processing | |
125 | * the first connection. | |
126 | */ | |
8efc0c15 | 127 | int debug_flag = 0; |
128 | ||
f87f09aa | 129 | /* Flag indicating that the daemon should only test the configuration and keys. */ |
130 | int test_flag = 0; | |
131 | ||
8efc0c15 | 132 | /* Flag indicating that the daemon is being started from inetd. */ |
133 | int inetd_flag = 0; | |
134 | ||
0b6fbf03 | 135 | /* Flag indicating that sshd should not detach and become a daemon. */ |
136 | int no_daemon_flag = 0; | |
137 | ||
6a17f9c2 | 138 | /* debug goes to stderr unless inetd_flag is set */ |
139 | int log_stderr = 0; | |
140 | ||
8efc0c15 | 141 | /* Saved arguments to main(). */ |
142 | char **saved_argv; | |
4d33e531 | 143 | int saved_argc; |
8efc0c15 | 144 | |
aa3378df | 145 | /* |
48e671d5 | 146 | * The sockets that the server is listening; this is used in the SIGHUP |
147 | * signal handler. | |
aa3378df | 148 | */ |
48e671d5 | 149 | #define MAX_LISTEN_SOCKS 16 |
150 | int listen_socks[MAX_LISTEN_SOCKS]; | |
151 | int num_listen_socks = 0; | |
8efc0c15 | 152 | |
aa3378df | 153 | /* |
154 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
155 | * sshd will skip the version-number exchange | |
156 | */ | |
5260325f | 157 | char *client_version_string = NULL; |
7368a6c8 | 158 | char *server_version_string = NULL; |
8efc0c15 | 159 | |
7a37c112 | 160 | /* for rekeying XXX fixme */ |
161 | Kex *xxx_kex; | |
162 | ||
aa3378df | 163 | /* |
164 | * Any really sensitive data in the application is contained in this | |
165 | * structure. The idea is that this structure could be locked into memory so | |
166 | * that the pages do not get written into swap. However, there are some | |
167 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
168 | * have access to the internals of them, and locking just the structure is | |
169 | * not very useful. Currently, memory locking is not implemented. | |
170 | */ | |
5260325f | 171 | struct { |
cb7bd922 | 172 | Key *server_key; /* ephemeral server key */ |
fa08c86b | 173 | Key *ssh1_host_key; /* ssh1 host key */ |
174 | Key **host_keys; /* all private host keys */ | |
175 | int have_ssh1_key; | |
176 | int have_ssh2_key; | |
00be5382 | 177 | u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; |
8efc0c15 | 178 | } sensitive_data; |
179 | ||
aa3378df | 180 | /* |
59c97189 | 181 | * Flag indicating whether the RSA server key needs to be regenerated. |
182 | * Is set in the SIGALRM handler and cleared when the key is regenerated. | |
aa3378df | 183 | */ |
7a934d1b | 184 | static volatile sig_atomic_t key_do_regen = 0; |
8efc0c15 | 185 | |
c9130033 | 186 | /* This is set to true when a signal is received. */ |
7a934d1b | 187 | static volatile sig_atomic_t received_sighup = 0; |
188 | static volatile sig_atomic_t received_sigterm = 0; | |
8efc0c15 | 189 | |
7368a6c8 | 190 | /* session identifier, used by RSA-auth */ |
1e3b8b07 | 191 | u_char session_id[16]; |
e7c0f9d5 | 192 | |
a306f2dd | 193 | /* same for ssh2 */ |
1e3b8b07 | 194 | u_char *session_id2 = NULL; |
a306f2dd | 195 | int session_id2_len = 0; |
196 | ||
c345cf9d | 197 | /* record remote hostname or ip */ |
1e3b8b07 | 198 | u_int utmp_len = MAXHOSTNAMELEN; |
c345cf9d | 199 | |
7ace8c3b | 200 | /* options.max_startup sized array of fd ints */ |
201 | int *startup_pipes = NULL; | |
202 | int startup_pipe; /* in child */ | |
203 | ||
1853d1ef | 204 | /* variables used for privilege separation */ |
b5a28cbc | 205 | extern struct monitor *pmonitor; |
1853d1ef | 206 | extern int use_privsep; |
207 | ||
7368a6c8 | 208 | /* Prototypes for various functions defined later in this file. */ |
396c147e | 209 | void destroy_sensitive_data(void); |
1853d1ef | 210 | void demote_sensitive_data(void); |
c8d54615 | 211 | |
396c147e | 212 | static void do_ssh1_kex(void); |
213 | static void do_ssh2_kex(void); | |
94ec8c6b | 214 | |
48e671d5 | 215 | /* |
216 | * Close all listening sockets | |
217 | */ | |
396c147e | 218 | static void |
48e671d5 | 219 | close_listen_socks(void) |
220 | { | |
221 | int i; | |
e424e241 | 222 | |
48e671d5 | 223 | for (i = 0; i < num_listen_socks; i++) |
224 | close(listen_socks[i]); | |
225 | num_listen_socks = -1; | |
226 | } | |
227 | ||
7ace8c3b | 228 | static void |
229 | close_startup_pipes(void) | |
230 | { | |
231 | int i; | |
e424e241 | 232 | |
7ace8c3b | 233 | if (startup_pipes) |
234 | for (i = 0; i < options.max_startups; i++) | |
235 | if (startup_pipes[i] != -1) | |
236 | close(startup_pipes[i]); | |
237 | } | |
238 | ||
5260325f | 239 | /* |
240 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
241 | * the effect is to reread the configuration file (and to regenerate | |
242 | * the server key). | |
243 | */ | |
396c147e | 244 | static void |
5260325f | 245 | sighup_handler(int sig) |
8efc0c15 | 246 | { |
6056eb35 | 247 | int save_errno = errno; |
248 | ||
5260325f | 249 | received_sighup = 1; |
250 | signal(SIGHUP, sighup_handler); | |
6056eb35 | 251 | errno = save_errno; |
8efc0c15 | 252 | } |
253 | ||
5260325f | 254 | /* |
255 | * Called from the main program after receiving SIGHUP. | |
256 | * Restarts the server. | |
257 | */ | |
396c147e | 258 | static void |
5ca51e19 | 259 | sighup_restart(void) |
8efc0c15 | 260 | { |
5260325f | 261 | log("Received SIGHUP; restarting."); |
48e671d5 | 262 | close_listen_socks(); |
7ace8c3b | 263 | close_startup_pipes(); |
5260325f | 264 | execv(saved_argv[0], saved_argv); |
e424e241 | 265 | log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], |
266 | strerror(errno)); | |
5260325f | 267 | exit(1); |
8efc0c15 | 268 | } |
269 | ||
5260325f | 270 | /* |
271 | * Generic signal handler for terminating signals in the master daemon. | |
5260325f | 272 | */ |
396c147e | 273 | static void |
5260325f | 274 | sigterm_handler(int sig) |
8efc0c15 | 275 | { |
c9130033 | 276 | received_sigterm = sig; |
8efc0c15 | 277 | } |
278 | ||
5260325f | 279 | /* |
280 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
c9130033 | 281 | * reap any zombies left by exited children. |
5260325f | 282 | */ |
396c147e | 283 | static void |
5260325f | 284 | main_sigchld_handler(int sig) |
8efc0c15 | 285 | { |
5260325f | 286 | int save_errno = errno; |
e424e241 | 287 | pid_t pid; |
5260325f | 288 | int status; |
5ad13cd7 | 289 | |
8c38e88b | 290 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || |
291 | (pid < 0 && errno == EINTR)) | |
5260325f | 292 | ; |
5ad13cd7 | 293 | |
5260325f | 294 | signal(SIGCHLD, main_sigchld_handler); |
295 | errno = save_errno; | |
8efc0c15 | 296 | } |
297 | ||
5260325f | 298 | /* |
299 | * Signal handler for the alarm after the login grace period has expired. | |
300 | */ | |
396c147e | 301 | static void |
5260325f | 302 | grace_alarm_handler(int sig) |
8efc0c15 | 303 | { |
c9130033 | 304 | /* XXX no idea how fix this signal handler */ |
305 | ||
5260325f | 306 | /* Close the connection. */ |
307 | packet_close(); | |
8efc0c15 | 308 | |
5260325f | 309 | /* Log error and exit. */ |
310 | fatal("Timeout before authentication for %s.", get_remote_ipaddr()); | |
311 | } | |
8efc0c15 | 312 | |
5260325f | 313 | /* |
314 | * Signal handler for the key regeneration alarm. Note that this | |
315 | * alarm only occurs in the daemon waiting for connections, and it does not | |
316 | * do anything with the private key or random state before forking. | |
317 | * Thus there should be no concurrency control/asynchronous execution | |
318 | * problems. | |
319 | */ | |
396c147e | 320 | static void |
cb7bd922 | 321 | generate_ephemeral_server_key(void) |
fa08c86b | 322 | { |
00be5382 | 323 | u_int32_t rand = 0; |
324 | int i; | |
325 | ||
cd332296 | 326 | verbose("Generating %s%d bit RSA key.", |
76ca7b01 | 327 | sensitive_data.server_key ? "new " : "", options.server_key_bits); |
fa08c86b | 328 | if (sensitive_data.server_key != NULL) |
329 | key_free(sensitive_data.server_key); | |
cd332296 | 330 | sensitive_data.server_key = key_generate(KEY_RSA1, |
76ca7b01 | 331 | options.server_key_bits); |
332 | verbose("RSA key generation complete."); | |
00be5382 | 333 | |
334 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
335 | if (i % 4 == 0) | |
336 | rand = arc4random(); | |
337 | sensitive_data.ssh1_cookie[i] = rand & 0xff; | |
338 | rand >>= 8; | |
339 | } | |
340 | arc4random_stir(); | |
fa08c86b | 341 | } |
f546c780 | 342 | |
396c147e | 343 | static void |
5260325f | 344 | key_regeneration_alarm(int sig) |
345 | { | |
346 | int save_errno = errno; | |
e424e241 | 347 | |
59c97189 | 348 | signal(SIGALRM, SIG_DFL); |
5260325f | 349 | errno = save_errno; |
59c97189 | 350 | key_do_regen = 1; |
5260325f | 351 | } |
8efc0c15 | 352 | |
396c147e | 353 | static void |
7368a6c8 | 354 | sshd_exchange_identification(int sock_in, int sock_out) |
355 | { | |
a8be9f80 | 356 | int i, mismatch; |
7368a6c8 | 357 | int remote_major, remote_minor; |
a8be9f80 | 358 | int major, minor; |
7368a6c8 | 359 | char *s; |
360 | char buf[256]; /* Must not be larger than remote_version. */ | |
361 | char remote_version[256]; /* Must be at least as big as buf. */ | |
362 | ||
a8be9f80 | 363 | if ((options.protocol & SSH_PROTO_1) && |
364 | (options.protocol & SSH_PROTO_2)) { | |
365 | major = PROTOCOL_MAJOR_1; | |
366 | minor = 99; | |
367 | } else if (options.protocol & SSH_PROTO_2) { | |
368 | major = PROTOCOL_MAJOR_2; | |
369 | minor = PROTOCOL_MINOR_2; | |
370 | } else { | |
371 | major = PROTOCOL_MAJOR_1; | |
372 | minor = PROTOCOL_MINOR_1; | |
373 | } | |
374 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
7368a6c8 | 375 | server_version_string = xstrdup(buf); |
376 | ||
377 | if (client_version_string == NULL) { | |
378 | /* Send our protocol version identification. */ | |
d6133f43 | 379 | if (atomicio(write, sock_out, server_version_string, |
380 | strlen(server_version_string)) | |
7368a6c8 | 381 | != strlen(server_version_string)) { |
30f60c34 | 382 | log("Could not write ident string to %s", get_remote_ipaddr()); |
7368a6c8 | 383 | fatal_cleanup(); |
384 | } | |
385 | ||
c242fc96 | 386 | /* Read other sides version identification. */ |
cd332296 | 387 | memset(buf, 0, sizeof(buf)); |
7368a6c8 | 388 | for (i = 0; i < sizeof(buf) - 1; i++) { |
e5a0294f | 389 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { |
30f60c34 | 390 | log("Did not receive identification string from %s", |
c2b544a5 | 391 | get_remote_ipaddr()); |
7368a6c8 | 392 | fatal_cleanup(); |
393 | } | |
394 | if (buf[i] == '\r') { | |
8a169574 | 395 | buf[i] = 0; |
94ec8c6b | 396 | /* Kludge for F-Secure Macintosh < 1.0.2 */ |
397 | if (i == 12 && | |
398 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
399 | break; | |
7368a6c8 | 400 | continue; |
7368a6c8 | 401 | } |
402 | if (buf[i] == '\n') { | |
8a169574 | 403 | buf[i] = 0; |
7368a6c8 | 404 | break; |
405 | } | |
406 | } | |
407 | buf[sizeof(buf) - 1] = 0; | |
408 | client_version_string = xstrdup(buf); | |
409 | } | |
410 | ||
411 | /* | |
412 | * Check that the versions match. In future this might accept | |
413 | * several versions and set appropriate flags to handle them. | |
414 | */ | |
415 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
416 | &remote_major, &remote_minor, remote_version) != 3) { | |
6ae2364d | 417 | s = "Protocol mismatch.\n"; |
7368a6c8 | 418 | (void) atomicio(write, sock_out, s, strlen(s)); |
419 | close(sock_in); | |
420 | close(sock_out); | |
421 | log("Bad protocol version identification '%.100s' from %s", | |
422 | client_version_string, get_remote_ipaddr()); | |
423 | fatal_cleanup(); | |
424 | } | |
425 | debug("Client protocol version %d.%d; client software version %.100s", | |
184eed6a | 426 | remote_major, remote_minor, remote_version); |
7368a6c8 | 427 | |
e78a59f5 | 428 | compat_datafellows(remote_version); |
429 | ||
3a1c54d4 | 430 | if (datafellows & SSH_BUG_SCANNER) { |
431 | log("scanned from %s with %s. Don't panic.", | |
432 | get_remote_ipaddr(), client_version_string); | |
433 | fatal_cleanup(); | |
434 | } | |
435 | ||
a8be9f80 | 436 | mismatch = 0; |
6aacefa7 | 437 | switch (remote_major) { |
7368a6c8 | 438 | case 1: |
a306f2dd | 439 | if (remote_minor == 99) { |
440 | if (options.protocol & SSH_PROTO_2) | |
441 | enable_compat20(); | |
442 | else | |
443 | mismatch = 1; | |
444 | break; | |
445 | } | |
a8be9f80 | 446 | if (!(options.protocol & SSH_PROTO_1)) { |
447 | mismatch = 1; | |
448 | break; | |
449 | } | |
7368a6c8 | 450 | if (remote_minor < 3) { |
089fbbd2 | 451 | packet_disconnect("Your ssh version is too old and " |
7368a6c8 | 452 | "is no longer supported. Please install a newer version."); |
453 | } else if (remote_minor == 3) { | |
454 | /* note that this disables agent-forwarding */ | |
455 | enable_compat13(); | |
456 | } | |
a8be9f80 | 457 | break; |
e78a59f5 | 458 | case 2: |
a8be9f80 | 459 | if (options.protocol & SSH_PROTO_2) { |
e78a59f5 | 460 | enable_compat20(); |
461 | break; | |
462 | } | |
463 | /* FALLTHROUGH */ | |
6ae2364d | 464 | default: |
a8be9f80 | 465 | mismatch = 1; |
466 | break; | |
467 | } | |
468 | chop(server_version_string); | |
a8be9f80 | 469 | debug("Local version string %.200s", server_version_string); |
470 | ||
471 | if (mismatch) { | |
7368a6c8 | 472 | s = "Protocol major versions differ.\n"; |
473 | (void) atomicio(write, sock_out, s, strlen(s)); | |
474 | close(sock_in); | |
475 | close(sock_out); | |
a8be9f80 | 476 | log("Protocol major versions differ for %s: %.200s vs. %.200s", |
477 | get_remote_ipaddr(), | |
478 | server_version_string, client_version_string); | |
7368a6c8 | 479 | fatal_cleanup(); |
7368a6c8 | 480 | } |
a306f2dd | 481 | } |
482 | ||
fa08c86b | 483 | /* Destroy the host and server keys. They will no longer be needed. */ |
a306f2dd | 484 | void |
485 | destroy_sensitive_data(void) | |
486 | { | |
fa08c86b | 487 | int i; |
488 | ||
489 | if (sensitive_data.server_key) { | |
490 | key_free(sensitive_data.server_key); | |
491 | sensitive_data.server_key = NULL; | |
492 | } | |
184eed6a | 493 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 494 | if (sensitive_data.host_keys[i]) { |
495 | key_free(sensitive_data.host_keys[i]); | |
496 | sensitive_data.host_keys[i] = NULL; | |
497 | } | |
498 | } | |
499 | sensitive_data.ssh1_host_key = NULL; | |
00be5382 | 500 | memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); |
fa08c86b | 501 | } |
fa08c86b | 502 | |
1853d1ef | 503 | /* Demote private to public keys for network child */ |
504 | void | |
505 | demote_sensitive_data(void) | |
506 | { | |
507 | Key *tmp; | |
508 | int i; | |
509 | ||
510 | if (sensitive_data.server_key) { | |
511 | tmp = key_demote(sensitive_data.server_key); | |
512 | key_free(sensitive_data.server_key); | |
513 | sensitive_data.server_key = tmp; | |
514 | } | |
515 | ||
516 | for (i = 0; i < options.num_host_key_files; i++) { | |
517 | if (sensitive_data.host_keys[i]) { | |
518 | tmp = key_demote(sensitive_data.host_keys[i]); | |
519 | key_free(sensitive_data.host_keys[i]); | |
520 | sensitive_data.host_keys[i] = tmp; | |
521 | if (tmp->type == KEY_RSA1) | |
522 | sensitive_data.ssh1_host_key = tmp; | |
523 | } | |
524 | } | |
525 | ||
526 | /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ | |
527 | } | |
528 | ||
51aeb639 | 529 | static void |
1853d1ef | 530 | privsep_preauth_child(void) |
531 | { | |
532 | u_int32_t rand[256]; | |
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++) | |
540 | rand[i] = arc4random(); | |
541 | RAND_seed(rand, sizeof(rand)); | |
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 | ||
1853d1ef | 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); | |
562 | do_setusercontext(pw); | |
1853d1ef | 563 | } |
564 | ||
324bf712 | 565 | static Authctxt* |
566 | privsep_preauth(void) | |
1853d1ef | 567 | { |
324bf712 | 568 | Authctxt *authctxt = NULL; |
1853d1ef | 569 | int status; |
324bf712 | 570 | pid_t pid; |
1853d1ef | 571 | |
324bf712 | 572 | /* Set up unprivileged child process to deal with network data */ |
b5a28cbc | 573 | pmonitor = monitor_init(); |
324bf712 | 574 | /* Store a pointer to the kex for later rekeying */ |
b5a28cbc | 575 | pmonitor->m_pkex = &xxx_kex; |
324bf712 | 576 | |
577 | pid = fork(); | |
578 | if (pid == -1) { | |
579 | fatal("fork of unprivileged child failed"); | |
580 | } else if (pid != 0) { | |
c457707e | 581 | debug2("Network child is on pid %ld", (long)pid); |
324bf712 | 582 | |
b5a28cbc | 583 | close(pmonitor->m_recvfd); |
584 | authctxt = monitor_child_preauth(pmonitor); | |
585 | close(pmonitor->m_sendfd); | |
324bf712 | 586 | |
587 | /* Sync memory */ | |
b5a28cbc | 588 | monitor_sync(pmonitor); |
324bf712 | 589 | |
590 | /* Wait for the child's exit status */ | |
8c38e88b | 591 | while (waitpid(pid, &status, 0) < 0) |
592 | if (errno != EINTR) | |
593 | break; | |
324bf712 | 594 | return (authctxt); |
595 | } else { | |
596 | /* child */ | |
597 | ||
b5a28cbc | 598 | close(pmonitor->m_sendfd); |
324bf712 | 599 | |
600 | /* Demote the child */ | |
601 | if (getuid() == 0 || geteuid() == 0) | |
602 | privsep_preauth_child(); | |
47c36e5b | 603 | setproctitle("%s", "[net]"); |
324bf712 | 604 | } |
605 | return (NULL); | |
606 | } | |
607 | ||
608 | static void | |
609 | privsep_postauth(Authctxt *authctxt) | |
610 | { | |
611 | extern Authctxt *x_authctxt; | |
1853d1ef | 612 | |
613 | /* XXX - Remote port forwarding */ | |
614 | x_authctxt = authctxt; | |
615 | ||
616 | if (authctxt->pw->pw_uid == 0 || options.use_login) { | |
617 | /* File descriptor passing is broken or root login */ | |
b5a28cbc | 618 | monitor_apply_keystate(pmonitor); |
1853d1ef | 619 | use_privsep = 0; |
620 | return; | |
621 | } | |
762715ce | 622 | |
1853d1ef | 623 | /* Authentication complete */ |
624 | alarm(0); | |
625 | if (startup_pipe != -1) { | |
626 | close(startup_pipe); | |
627 | startup_pipe = -1; | |
628 | } | |
629 | ||
630 | /* New socket pair */ | |
b5a28cbc | 631 | monitor_reinit(pmonitor); |
1853d1ef | 632 | |
b5a28cbc | 633 | pmonitor->m_pid = fork(); |
634 | if (pmonitor->m_pid == -1) | |
1853d1ef | 635 | fatal("fork of unprivileged child failed"); |
b5a28cbc | 636 | else if (pmonitor->m_pid != 0) { |
c457707e | 637 | debug2("User child is on pid %ld", (long)pmonitor->m_pid); |
b5a28cbc | 638 | close(pmonitor->m_recvfd); |
639 | monitor_child_postauth(pmonitor); | |
1853d1ef | 640 | |
641 | /* NEVERREACHED */ | |
642 | exit(0); | |
643 | } | |
644 | ||
b5a28cbc | 645 | close(pmonitor->m_sendfd); |
1853d1ef | 646 | |
647 | /* Demote the private keys to public keys. */ | |
648 | demote_sensitive_data(); | |
649 | ||
650 | /* Drop privileges */ | |
651 | do_setusercontext(authctxt->pw); | |
652 | ||
653 | /* It is safe now to apply the key state */ | |
b5a28cbc | 654 | monitor_apply_keystate(pmonitor); |
1853d1ef | 655 | } |
656 | ||
396c147e | 657 | static char * |
fa08c86b | 658 | list_hostkey_types(void) |
659 | { | |
3469eac4 | 660 | Buffer b; |
661 | char *p; | |
fa08c86b | 662 | int i; |
3469eac4 | 663 | |
664 | buffer_init(&b); | |
184eed6a | 665 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 666 | Key *key = sensitive_data.host_keys[i]; |
667 | if (key == NULL) | |
668 | continue; | |
6aacefa7 | 669 | switch (key->type) { |
fa08c86b | 670 | case KEY_RSA: |
671 | case KEY_DSA: | |
3469eac4 | 672 | if (buffer_len(&b) > 0) |
673 | buffer_append(&b, ",", 1); | |
674 | p = key_ssh_name(key); | |
675 | buffer_append(&b, p, strlen(p)); | |
fa08c86b | 676 | break; |
677 | } | |
678 | } | |
3469eac4 | 679 | buffer_append(&b, "\0", 1); |
680 | p = xstrdup(buffer_ptr(&b)); | |
681 | buffer_free(&b); | |
682 | debug("list_hostkey_types: %s", p); | |
683 | return p; | |
fa08c86b | 684 | } |
685 | ||
1853d1ef | 686 | Key * |
fa08c86b | 687 | get_hostkey_by_type(int type) |
688 | { | |
689 | int i; | |
e424e241 | 690 | |
184eed6a | 691 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 692 | Key *key = sensitive_data.host_keys[i]; |
693 | if (key != NULL && key->type == type) | |
694 | return key; | |
695 | } | |
696 | return NULL; | |
7368a6c8 | 697 | } |
698 | ||
1853d1ef | 699 | Key * |
700 | get_hostkey_by_index(int ind) | |
701 | { | |
702 | if (ind < 0 || ind >= options.num_host_key_files) | |
703 | return (NULL); | |
704 | return (sensitive_data.host_keys[ind]); | |
705 | } | |
706 | ||
707 | int | |
708 | get_hostkey_index(Key *key) | |
709 | { | |
710 | int i; | |
e424e241 | 711 | |
1853d1ef | 712 | for (i = 0; i < options.num_host_key_files; i++) { |
713 | if (key == sensitive_data.host_keys[i]) | |
714 | return (i); | |
715 | } | |
716 | return (-1); | |
717 | } | |
718 | ||
c345cf9d | 719 | /* |
720 | * returns 1 if connection should be dropped, 0 otherwise. | |
721 | * dropping starts at connection #max_startups_begin with a probability | |
722 | * of (max_startups_rate/100). the probability increases linearly until | |
723 | * all connections are dropped for startups > max_startups | |
724 | */ | |
396c147e | 725 | static int |
c345cf9d | 726 | drop_connection(int startups) |
727 | { | |
728 | double p, r; | |
729 | ||
730 | if (startups < options.max_startups_begin) | |
731 | return 0; | |
732 | if (startups >= options.max_startups) | |
733 | return 1; | |
734 | if (options.max_startups_rate == 100) | |
735 | return 1; | |
736 | ||
737 | p = 100 - options.max_startups_rate; | |
738 | p *= startups - options.max_startups_begin; | |
739 | p /= (double) (options.max_startups - options.max_startups_begin); | |
740 | p += options.max_startups_rate; | |
741 | p /= 100.0; | |
742 | r = arc4random() / (double) UINT_MAX; | |
743 | ||
744 | debug("drop_connection: p %g, r %g", p, r); | |
745 | return (r < p) ? 1 : 0; | |
746 | } | |
747 | ||
2717fa0f | 748 | static void |
749 | usage(void) | |
750 | { | |
751 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
752 | fprintf(stderr, "Usage: %s [options]\n", __progname); | |
753 | fprintf(stderr, "Options:\n"); | |
754 | fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE); | |
755 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); | |
756 | fprintf(stderr, " -i Started from inetd\n"); | |
757 | fprintf(stderr, " -D Do not fork into daemon mode\n"); | |
758 | fprintf(stderr, " -t Only test configuration file and keys\n"); | |
759 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
760 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
761 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
762 | fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n"); | |
763 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
764 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
765 | _PATH_HOST_KEY_FILE); | |
766 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); | |
767 | fprintf(stderr, " -4 Use IPv4 only\n"); | |
768 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
769 | fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n"); | |
770 | exit(1); | |
771 | } | |
772 | ||
5260325f | 773 | /* |
774 | * Main program for the daemon. | |
775 | */ | |
8efc0c15 | 776 | int |
777 | main(int ac, char **av) | |
778 | { | |
5260325f | 779 | extern char *optarg; |
780 | extern int optind; | |
089fbbd2 | 781 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; |
9da5c3c9 | 782 | pid_t pid; |
48e671d5 | 783 | socklen_t fromlen; |
48e671d5 | 784 | fd_set *fdset; |
785 | struct sockaddr_storage from; | |
5260325f | 786 | const char *remote_ip; |
787 | int remote_port; | |
5260325f | 788 | FILE *f; |
789 | struct linger linger; | |
48e671d5 | 790 | struct addrinfo *ai; |
791 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
792 | int listen_sock, maxfd; | |
089fbbd2 | 793 | int startup_p[2]; |
794 | int startups = 0; | |
1b34c1b3 | 795 | Authctxt *authctxt; |
aeaa3d9e | 796 | Key *key; |
59c97189 | 797 | int ret, key_used = 0; |
5260325f | 798 | |
6e879cb4 | 799 | #ifdef HAVE_SECUREWARE |
800 | (void)set_auth_parameters(ac, av); | |
801 | #endif | |
260d427b | 802 | __progname = get_progname(av[0]); |
264dce47 | 803 | init_rng(); |
804 | ||
1fe6a48f | 805 | /* Save argv. */ |
4d33e531 | 806 | saved_argc = ac; |
5260325f | 807 | saved_argv = av; |
5260325f | 808 | |
809 | /* Initialize configuration options to their default values. */ | |
810 | initialize_server_options(&options); | |
811 | ||
812 | /* Parse command-line arguments. */ | |
2717fa0f | 813 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) { |
5260325f | 814 | switch (opt) { |
48e671d5 | 815 | case '4': |
816 | IPv4or6 = AF_INET; | |
817 | break; | |
818 | case '6': | |
819 | IPv4or6 = AF_INET6; | |
820 | break; | |
5260325f | 821 | case 'f': |
822 | config_file_name = optarg; | |
823 | break; | |
824 | case 'd': | |
bcbf86ec | 825 | if (0 == debug_flag) { |
826 | debug_flag = 1; | |
827 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
828 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
829 | options.log_level++; | |
830 | } else { | |
831 | fprintf(stderr, "Too high debugging level.\n"); | |
832 | exit(1); | |
833 | } | |
5260325f | 834 | break; |
0b6fbf03 | 835 | case 'D': |
836 | no_daemon_flag = 1; | |
837 | break; | |
ff14faf1 | 838 | case 'e': |
839 | log_stderr = 1; | |
840 | break; | |
5260325f | 841 | case 'i': |
842 | inetd_flag = 1; | |
843 | break; | |
844 | case 'Q': | |
9bd5b720 | 845 | /* ignored */ |
5260325f | 846 | break; |
847 | case 'q': | |
848 | options.log_level = SYSLOG_LEVEL_QUIET; | |
849 | break; | |
850 | case 'b': | |
851 | options.server_key_bits = atoi(optarg); | |
852 | break; | |
853 | case 'p': | |
48e671d5 | 854 | options.ports_from_cmdline = 1; |
bcbf86ec | 855 | if (options.num_ports >= MAX_PORTS) { |
856 | fprintf(stderr, "too many ports.\n"); | |
857 | exit(1); | |
858 | } | |
2d2a2c65 | 859 | options.ports[options.num_ports++] = a2port(optarg); |
860 | if (options.ports[options.num_ports-1] == 0) { | |
861 | fprintf(stderr, "Bad port number.\n"); | |
862 | exit(1); | |
863 | } | |
5260325f | 864 | break; |
865 | case 'g': | |
e2b1fb42 | 866 | if ((options.login_grace_time = convtime(optarg)) == -1) { |
867 | fprintf(stderr, "Invalid login grace time.\n"); | |
868 | exit(1); | |
869 | } | |
5260325f | 870 | break; |
871 | case 'k': | |
e2b1fb42 | 872 | if ((options.key_regeneration_time = convtime(optarg)) == -1) { |
873 | fprintf(stderr, "Invalid key regeneration interval.\n"); | |
874 | exit(1); | |
875 | } | |
5260325f | 876 | break; |
877 | case 'h': | |
fa08c86b | 878 | if (options.num_host_key_files >= MAX_HOSTKEYS) { |
879 | fprintf(stderr, "too many host keys.\n"); | |
880 | exit(1); | |
881 | } | |
882 | options.host_key_files[options.num_host_key_files++] = optarg; | |
5260325f | 883 | break; |
884 | case 'V': | |
885 | client_version_string = optarg; | |
886 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
887 | inetd_flag = 1; | |
888 | break; | |
f87f09aa | 889 | case 't': |
890 | test_flag = 1; | |
891 | break; | |
c345cf9d | 892 | case 'u': |
893 | utmp_len = atoi(optarg); | |
894 | break; | |
2717fa0f | 895 | case 'o': |
184eed6a | 896 | if (process_server_config_line(&options, optarg, |
2717fa0f | 897 | "command-line", 0) != 0) |
184eed6a | 898 | exit(1); |
2717fa0f | 899 | break; |
5260325f | 900 | case '?': |
901 | default: | |
2717fa0f | 902 | usage(); |
903 | break; | |
5260325f | 904 | } |
905 | } | |
1a92bd7e | 906 | SSLeay_add_all_algorithms(); |
5e4a7219 | 907 | channel_set_af(IPv4or6); |
5260325f | 908 | |
48e671d5 | 909 | /* |
910 | * Force logging to stderr until we have loaded the private host | |
911 | * key (unless started from inetd) | |
912 | */ | |
1fe6a48f | 913 | log_init(__progname, |
980c9344 | 914 | options.log_level == SYSLOG_LEVEL_NOT_SET ? |
915 | SYSLOG_LEVEL_INFO : options.log_level, | |
916 | options.log_facility == SYSLOG_FACILITY_NOT_SET ? | |
917 | SYSLOG_FACILITY_AUTH : options.log_facility, | |
9bd5b720 | 918 | !inetd_flag); |
48e671d5 | 919 | |
1a23ac2c | 920 | #ifdef _CRAY |
921 | /* Cray can define user privs drop all prives now! | |
922 | * Not needed on PRIV_SU systems! | |
923 | */ | |
924 | drop_cray_privs(); | |
925 | #endif | |
926 | ||
e339aa53 | 927 | seed_rng(); |
928 | ||
5260325f | 929 | /* Read server configuration options from the configuration file. */ |
930 | read_server_config(&options, config_file_name); | |
931 | ||
932 | /* Fill in default values for those options not explicitly set. */ | |
933 | fill_default_server_options(&options); | |
934 | ||
5260325f | 935 | /* Check that there are no remaining arguments. */ |
936 | if (optind < ac) { | |
937 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
938 | exit(1); | |
8efc0c15 | 939 | } |
5260325f | 940 | |
941 | debug("sshd version %.100s", SSH_VERSION); | |
942 | ||
fa08c86b | 943 | /* load private host keys */ |
944 | sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*)); | |
184eed6a | 945 | for (i = 0; i < options.num_host_key_files; i++) |
1e3b8b07 | 946 | sensitive_data.host_keys[i] = NULL; |
fa08c86b | 947 | sensitive_data.server_key = NULL; |
948 | sensitive_data.ssh1_host_key = NULL; | |
949 | sensitive_data.have_ssh1_key = 0; | |
950 | sensitive_data.have_ssh2_key = 0; | |
a306f2dd | 951 | |
184eed6a | 952 | for (i = 0; i < options.num_host_key_files; i++) { |
aeaa3d9e | 953 | key = key_load_private(options.host_key_files[i], "", NULL); |
954 | sensitive_data.host_keys[i] = key; | |
fa08c86b | 955 | if (key == NULL) { |
58cfa257 | 956 | error("Could not load host key: %s", |
957 | options.host_key_files[i]); | |
aeaa3d9e | 958 | sensitive_data.host_keys[i] = NULL; |
fa08c86b | 959 | continue; |
a306f2dd | 960 | } |
6aacefa7 | 961 | switch (key->type) { |
fa08c86b | 962 | case KEY_RSA1: |
963 | sensitive_data.ssh1_host_key = key; | |
964 | sensitive_data.have_ssh1_key = 1; | |
965 | break; | |
966 | case KEY_RSA: | |
967 | case KEY_DSA: | |
968 | sensitive_data.have_ssh2_key = 1; | |
969 | break; | |
a306f2dd | 970 | } |
aeaa3d9e | 971 | debug("private host key: #%d type %d %s", i, key->type, |
972 | key_type(key)); | |
fa08c86b | 973 | } |
974 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
975 | log("Disabling protocol version 1. Could not load host key"); | |
976 | options.protocol &= ~SSH_PROTO_1; | |
977 | } | |
978 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
979 | log("Disabling protocol version 2. Could not load host key"); | |
980 | options.protocol &= ~SSH_PROTO_2; | |
a306f2dd | 981 | } |
6a416424 | 982 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { |
54b974dc | 983 | log("sshd: no hostkeys available -- exiting."); |
5260325f | 984 | exit(1); |
985 | } | |
5260325f | 986 | |
a306f2dd | 987 | /* Check certain values for sanity. */ |
988 | if (options.protocol & SSH_PROTO_1) { | |
989 | if (options.server_key_bits < 512 || | |
990 | options.server_key_bits > 32768) { | |
991 | fprintf(stderr, "Bad server key size.\n"); | |
992 | exit(1); | |
993 | } | |
994 | /* | |
995 | * Check that server and host key lengths differ sufficiently. This | |
996 | * is necessary to make double encryption work with rsaref. Oh, I | |
997 | * hate software patents. I dont know if this can go? Niels | |
998 | */ | |
999 | if (options.server_key_bits > | |
e424e241 | 1000 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - |
1001 | SSH_KEY_BITS_RESERVED && options.server_key_bits < | |
1002 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1003 | SSH_KEY_BITS_RESERVED) { | |
a306f2dd | 1004 | options.server_key_bits = |
e424e241 | 1005 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + |
1006 | SSH_KEY_BITS_RESERVED; | |
a306f2dd | 1007 | debug("Forcing server key to %d bits to make it differ from host key.", |
1008 | options.server_key_bits); | |
1009 | } | |
1010 | } | |
1011 | ||
3cc54fbb | 1012 | if (use_privsep) { |
1013 | struct passwd *pw; | |
1014 | struct stat st; | |
1015 | ||
1016 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
1017 | fatal("Privilege separation user %s does not exist", | |
1018 | SSH_PRIVSEP_USER); | |
1019 | if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || | |
1020 | (S_ISDIR(st.st_mode) == 0)) | |
1021 | fatal("Missing privilege separation directory: %s", | |
1022 | _PATH_PRIVSEP_CHROOT_DIR); | |
a56313d7 | 1023 | if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) |
1024 | fatal("Bad owner or mode for %s", | |
1025 | _PATH_PRIVSEP_CHROOT_DIR); | |
3cc54fbb | 1026 | } |
1027 | ||
f87f09aa | 1028 | /* Configuration looks good, so exit if in test mode. */ |
1029 | if (test_flag) | |
1030 | exit(0); | |
1031 | ||
018a5ea3 | 1032 | /* |
1033 | * Clear out any supplemental groups we may have inherited. This | |
1034 | * prevents inadvertent creation of files with bad modes (in the | |
1035 | * portable version at least, it's certainly possible for PAM | |
1036 | * to create a file, and we can't control the code in every | |
1037 | * module which might be used). | |
1038 | */ | |
1039 | if (setgroups(0, NULL) < 0) | |
1040 | debug("setgroups() failed: %.200s", strerror(errno)); | |
1041 | ||
a306f2dd | 1042 | /* Initialize the log (it is reinitialized below in case we forked). */ |
5260325f | 1043 | if (debug_flag && !inetd_flag) |
1044 | log_stderr = 1; | |
1fe6a48f | 1045 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 1046 | |
a306f2dd | 1047 | /* |
1048 | * If not in debugging mode, and not started from inetd, disconnect | |
1049 | * from the controlling terminal, and fork. The original process | |
1050 | * exits. | |
1051 | */ | |
0b6fbf03 | 1052 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { |
8efc0c15 | 1053 | #ifdef TIOCNOTTY |
5260325f | 1054 | int fd; |
8efc0c15 | 1055 | #endif /* TIOCNOTTY */ |
5260325f | 1056 | if (daemon(0, 0) < 0) |
1057 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1058 | ||
1059 | /* Disconnect from the controlling tty. */ | |
8efc0c15 | 1060 | #ifdef TIOCNOTTY |
5ca51e19 | 1061 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); |
5260325f | 1062 | if (fd >= 0) { |
1063 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
1064 | close(fd); | |
1065 | } | |
8efc0c15 | 1066 | #endif /* TIOCNOTTY */ |
8efc0c15 | 1067 | } |
5260325f | 1068 | /* Reinitialize the log (because of the fork above). */ |
1fe6a48f | 1069 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 1070 | |
5260325f | 1071 | /* Initialize the random number generator. */ |
1072 | arc4random_stir(); | |
1073 | ||
1074 | /* Chdir to the root directory so that the current disk can be | |
1075 | unmounted if desired. */ | |
1076 | chdir("/"); | |
184eed6a | 1077 | |
1d3c30db | 1078 | /* ignore SIGPIPE */ |
1079 | signal(SIGPIPE, SIG_IGN); | |
5260325f | 1080 | |
5260325f | 1081 | /* Start listening for a socket, unless started from inetd. */ |
1082 | if (inetd_flag) { | |
ec1f12d3 | 1083 | int s1; |
5260325f | 1084 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ |
ec1f12d3 | 1085 | dup(s1); |
5260325f | 1086 | sock_in = dup(0); |
1087 | sock_out = dup(1); | |
4c8722d9 | 1088 | startup_pipe = -1; |
a306f2dd | 1089 | /* |
1090 | * We intentionally do not close the descriptors 0, 1, and 2 | |
1091 | * as our code for setting the descriptors won\'t work if | |
1092 | * ttyfd happens to be one of those. | |
1093 | */ | |
5260325f | 1094 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); |
fa08c86b | 1095 | if (options.protocol & SSH_PROTO_1) |
cb7bd922 | 1096 | generate_ephemeral_server_key(); |
5260325f | 1097 | } else { |
48e671d5 | 1098 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
1099 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
1100 | continue; | |
1101 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
1102 | fatal("Too many listen sockets. " | |
1103 | "Enlarge MAX_LISTEN_SOCKS"); | |
1104 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
1105 | ntop, sizeof(ntop), strport, sizeof(strport), | |
1106 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
1107 | error("getnameinfo failed"); | |
1108 | continue; | |
1109 | } | |
1110 | /* Create socket for listening. */ | |
1111 | listen_sock = socket(ai->ai_family, SOCK_STREAM, 0); | |
1112 | if (listen_sock < 0) { | |
1113 | /* kernel may not support ipv6 */ | |
1114 | verbose("socket: %.100s", strerror(errno)); | |
1115 | continue; | |
1116 | } | |
1117 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
1118 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
1119 | close(listen_sock); | |
1120 | continue; | |
1121 | } | |
1122 | /* | |
1123 | * Set socket options. We try to make the port | |
1124 | * reusable and have it close as fast as possible | |
1125 | * without waiting in unnecessary wait states on | |
1126 | * close. | |
1127 | */ | |
1128 | setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, | |
db518d9b | 1129 | &on, sizeof(on)); |
48e671d5 | 1130 | linger.l_onoff = 1; |
1131 | linger.l_linger = 5; | |
1132 | setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, | |
db518d9b | 1133 | &linger, sizeof(linger)); |
48e671d5 | 1134 | |
1135 | debug("Bind to port %s on %s.", strport, ntop); | |
1136 | ||
1137 | /* Bind the socket to the desired port. */ | |
32ced054 | 1138 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { |
1139 | if (!ai->ai_next) | |
1140 | error("Bind to port %s on %s failed: %.200s.", | |
1141 | strport, ntop, strerror(errno)); | |
48e671d5 | 1142 | close(listen_sock); |
1143 | continue; | |
1144 | } | |
1145 | listen_socks[num_listen_socks] = listen_sock; | |
1146 | num_listen_socks++; | |
1147 | ||
1148 | /* Start listening on the port. */ | |
1149 | log("Server listening on %s port %s.", ntop, strport); | |
1150 | if (listen(listen_sock, 5) < 0) | |
1151 | fatal("listen: %.100s", strerror(errno)); | |
1152 | ||
5260325f | 1153 | } |
48e671d5 | 1154 | freeaddrinfo(options.listen_addrs); |
1155 | ||
1156 | if (!num_listen_socks) | |
1157 | fatal("Cannot bind any address."); | |
1158 | ||
3aca00a3 | 1159 | if (options.protocol & SSH_PROTO_1) |
1160 | generate_ephemeral_server_key(); | |
1161 | ||
1162 | /* | |
1163 | * Arrange to restart on SIGHUP. The handler needs | |
1164 | * listen_sock. | |
1165 | */ | |
1166 | signal(SIGHUP, sighup_handler); | |
1167 | ||
1168 | signal(SIGTERM, sigterm_handler); | |
1169 | signal(SIGQUIT, sigterm_handler); | |
1170 | ||
1171 | /* Arrange SIGCHLD to be caught. */ | |
1172 | signal(SIGCHLD, main_sigchld_handler); | |
1173 | ||
1174 | /* Write out the pid file after the sigterm handler is setup */ | |
5260325f | 1175 | if (!debug_flag) { |
aa3378df | 1176 | /* |
97fb6912 | 1177 | * Record our pid in /var/run/sshd.pid to make it |
1178 | * easier to kill the correct sshd. We don't want to | |
1179 | * do this before the bind above because the bind will | |
aa3378df | 1180 | * fail if there already is a daemon, and this will |
1181 | * overwrite any old pid in the file. | |
1182 | */ | |
3c62e7eb | 1183 | f = fopen(options.pid_file, "wb"); |
5260325f | 1184 | if (f) { |
c457707e | 1185 | fprintf(f, "%ld\n", (long) getpid()); |
5260325f | 1186 | fclose(f); |
1187 | } | |
8efc0c15 | 1188 | } |
5260325f | 1189 | |
48e671d5 | 1190 | /* setup fd set for listen */ |
089fbbd2 | 1191 | fdset = NULL; |
48e671d5 | 1192 | maxfd = 0; |
1193 | for (i = 0; i < num_listen_socks; i++) | |
1194 | if (listen_socks[i] > maxfd) | |
1195 | maxfd = listen_socks[i]; | |
089fbbd2 | 1196 | /* pipes connected to unauthenticated childs */ |
1197 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
1198 | for (i = 0; i < options.max_startups; i++) | |
1199 | startup_pipes[i] = -1; | |
48e671d5 | 1200 | |
aa3378df | 1201 | /* |
1202 | * Stay listening for connections until the system crashes or | |
1203 | * the daemon is killed with a signal. | |
1204 | */ | |
5260325f | 1205 | for (;;) { |
1206 | if (received_sighup) | |
1207 | sighup_restart(); | |
089fbbd2 | 1208 | if (fdset != NULL) |
1209 | xfree(fdset); | |
b5c334cc | 1210 | fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); |
089fbbd2 | 1211 | fdset = (fd_set *)xmalloc(fdsetsz); |
48e671d5 | 1212 | memset(fdset, 0, fdsetsz); |
089fbbd2 | 1213 | |
48e671d5 | 1214 | for (i = 0; i < num_listen_socks; i++) |
1215 | FD_SET(listen_socks[i], fdset); | |
089fbbd2 | 1216 | for (i = 0; i < options.max_startups; i++) |
1217 | if (startup_pipes[i] != -1) | |
1218 | FD_SET(startup_pipes[i], fdset); | |
1219 | ||
1220 | /* Wait in select until there is a connection. */ | |
59c97189 | 1221 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); |
1222 | if (ret < 0 && errno != EINTR) | |
1223 | error("select: %.100s", strerror(errno)); | |
c9130033 | 1224 | if (received_sigterm) { |
1225 | log("Received signal %d; terminating.", | |
010f9726 | 1226 | (int) received_sigterm); |
c9130033 | 1227 | close_listen_socks(); |
1228 | unlink(options.pid_file); | |
1229 | exit(255); | |
1230 | } | |
59c97189 | 1231 | if (key_used && key_do_regen) { |
cb7bd922 | 1232 | generate_ephemeral_server_key(); |
59c97189 | 1233 | key_used = 0; |
1234 | key_do_regen = 0; | |
48e671d5 | 1235 | } |
59c97189 | 1236 | if (ret < 0) |
1237 | continue; | |
1238 | ||
089fbbd2 | 1239 | for (i = 0; i < options.max_startups; i++) |
1240 | if (startup_pipes[i] != -1 && | |
1241 | FD_ISSET(startup_pipes[i], fdset)) { | |
1242 | /* | |
1243 | * the read end of the pipe is ready | |
1244 | * if the child has closed the pipe | |
8abcdba4 | 1245 | * after successful authentication |
089fbbd2 | 1246 | * or if the child has died |
1247 | */ | |
1248 | close(startup_pipes[i]); | |
1249 | startup_pipes[i] = -1; | |
1250 | startups--; | |
1251 | } | |
48e671d5 | 1252 | for (i = 0; i < num_listen_socks; i++) { |
1253 | if (!FD_ISSET(listen_socks[i], fdset)) | |
5260325f | 1254 | continue; |
089fbbd2 | 1255 | fromlen = sizeof(from); |
1256 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
1257 | &fromlen); | |
1258 | if (newsock < 0) { | |
1259 | if (errno != EINTR && errno != EWOULDBLOCK) | |
1260 | error("accept: %.100s", strerror(errno)); | |
1261 | continue; | |
1262 | } | |
1263 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
1264 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
5e8948af | 1265 | close(newsock); |
089fbbd2 | 1266 | continue; |
1267 | } | |
c345cf9d | 1268 | if (drop_connection(startups) == 1) { |
1269 | debug("drop connection #%d", startups); | |
089fbbd2 | 1270 | close(newsock); |
1271 | continue; | |
1272 | } | |
1273 | if (pipe(startup_p) == -1) { | |
1274 | close(newsock); | |
1275 | continue; | |
1276 | } | |
1277 | ||
1278 | for (j = 0; j < options.max_startups; j++) | |
1279 | if (startup_pipes[j] == -1) { | |
1280 | startup_pipes[j] = startup_p[0]; | |
1281 | if (maxfd < startup_p[0]) | |
1282 | maxfd = startup_p[0]; | |
1283 | startups++; | |
1284 | break; | |
1285 | } | |
2b87da3b | 1286 | |
aa3378df | 1287 | /* |
089fbbd2 | 1288 | * Got connection. Fork a child to handle it, unless |
1289 | * we are in debugging mode. | |
aa3378df | 1290 | */ |
089fbbd2 | 1291 | if (debug_flag) { |
aa3378df | 1292 | /* |
089fbbd2 | 1293 | * In debugging mode. Close the listening |
1294 | * socket, and start processing the | |
1295 | * connection without forking. | |
aa3378df | 1296 | */ |
089fbbd2 | 1297 | debug("Server will not fork when running in debugging mode."); |
48e671d5 | 1298 | close_listen_socks(); |
5260325f | 1299 | sock_in = newsock; |
1300 | sock_out = newsock; | |
5540ea9b | 1301 | startup_pipe = -1; |
3f7a7e4a | 1302 | pid = getpid(); |
5260325f | 1303 | break; |
089fbbd2 | 1304 | } else { |
1305 | /* | |
1306 | * Normal production daemon. Fork, and have | |
1307 | * the child process the connection. The | |
1308 | * parent continues listening. | |
1309 | */ | |
1310 | if ((pid = fork()) == 0) { | |
1311 | /* | |
1312 | * Child. Close the listening and max_startup | |
1313 | * sockets. Start using the accepted socket. | |
1314 | * Reinitialize logging (since our pid has | |
1315 | * changed). We break out of the loop to handle | |
1316 | * the connection. | |
1317 | */ | |
1318 | startup_pipe = startup_p[1]; | |
7ace8c3b | 1319 | close_startup_pipes(); |
089fbbd2 | 1320 | close_listen_socks(); |
1321 | sock_in = newsock; | |
1322 | sock_out = newsock; | |
1fe6a48f | 1323 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
089fbbd2 | 1324 | break; |
1325 | } | |
5260325f | 1326 | } |
5260325f | 1327 | |
089fbbd2 | 1328 | /* Parent. Stay in the loop. */ |
1329 | if (pid < 0) | |
1330 | error("fork: %.100s", strerror(errno)); | |
1331 | else | |
c457707e | 1332 | debug("Forked child %ld.", (long)pid); |
5260325f | 1333 | |
089fbbd2 | 1334 | close(startup_p[1]); |
5260325f | 1335 | |
089fbbd2 | 1336 | /* Mark that the key has been used (it was "given" to the child). */ |
59c97189 | 1337 | if ((options.protocol & SSH_PROTO_1) && |
1338 | key_used == 0) { | |
1339 | /* Schedule server key regeneration alarm. */ | |
1340 | signal(SIGALRM, key_regeneration_alarm); | |
1341 | alarm(options.key_regeneration_time); | |
1342 | key_used = 1; | |
1343 | } | |
5260325f | 1344 | |
089fbbd2 | 1345 | arc4random_stir(); |
1346 | ||
1347 | /* Close the new socket (the child is now taking care of it). */ | |
1348 | close(newsock); | |
1349 | } | |
48e671d5 | 1350 | /* child process check (or debug mode) */ |
1351 | if (num_listen_socks < 0) | |
1352 | break; | |
5260325f | 1353 | } |
1354 | } | |
8efc0c15 | 1355 | |
5260325f | 1356 | /* This is the child processing a new connection. */ |
1357 | ||
4ac8556b | 1358 | /* |
1359 | * Create a new session and process group since the 4.4BSD | |
1360 | * setlogin() affects the entire process group. We don't | |
1361 | * want the child to be able to affect the parent. | |
1362 | */ | |
30321a9b | 1363 | #if 0 |
1364 | /* XXX: this breaks Solaris */ | |
c28876e9 | 1365 | if (!debug_flag && !inetd_flag && setsid() < 0) |
4ac8556b | 1366 | error("setsid: %.100s", strerror(errno)); |
30321a9b | 1367 | #endif |
4ac8556b | 1368 | |
aa3378df | 1369 | /* |
1370 | * Disable the key regeneration alarm. We will not regenerate the | |
1371 | * key since we are no longer in a position to give it to anyone. We | |
1372 | * will not restart on SIGHUP since it no longer makes sense. | |
1373 | */ | |
5260325f | 1374 | alarm(0); |
1375 | signal(SIGALRM, SIG_DFL); | |
1376 | signal(SIGHUP, SIG_DFL); | |
1377 | signal(SIGTERM, SIG_DFL); | |
1378 | signal(SIGQUIT, SIG_DFL); | |
1379 | signal(SIGCHLD, SIG_DFL); | |
9aaf9be4 | 1380 | signal(SIGINT, SIG_DFL); |
5260325f | 1381 | |
aa3378df | 1382 | /* |
1383 | * Set socket options for the connection. We want the socket to | |
1384 | * close as fast as possible without waiting for anything. If the | |
1385 | * connection is not a socket, these will do nothing. | |
1386 | */ | |
1387 | /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 1388 | linger.l_onoff = 1; |
1389 | linger.l_linger = 5; | |
db518d9b | 1390 | setsockopt(sock_in, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger)); |
5260325f | 1391 | |
b5c334cc | 1392 | /* Set keepalives if requested. */ |
1393 | if (options.keepalives && | |
db518d9b | 1394 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, |
b5c334cc | 1395 | sizeof(on)) < 0) |
1396 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1397 | ||
aa3378df | 1398 | /* |
1399 | * Register our connection. This turns encryption off because we do | |
1400 | * not have a key. | |
1401 | */ | |
5260325f | 1402 | packet_set_connection(sock_in, sock_out); |
1403 | ||
1404 | remote_port = get_remote_port(); | |
1405 | remote_ip = get_remote_ipaddr(); | |
1406 | ||
5260325f | 1407 | #ifdef LIBWRAP |
ac28afd8 | 1408 | /* Check whether logins are denied from this host. */ |
5260325f | 1409 | { |
1410 | struct request_info req; | |
8efc0c15 | 1411 | |
8fbc356d | 1412 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); |
5260325f | 1413 | fromhost(&req); |
8efc0c15 | 1414 | |
5260325f | 1415 | if (!hosts_access(&req)) { |
ac28afd8 | 1416 | debug("Connection refused by tcp wrapper"); |
563834bb | 1417 | refuse(&req); |
ac28afd8 | 1418 | /* NOTREACHED */ |
1419 | fatal("libwrap refuse returns"); | |
5260325f | 1420 | } |
8efc0c15 | 1421 | } |
48e671d5 | 1422 | #endif /* LIBWRAP */ |
ac28afd8 | 1423 | |
5260325f | 1424 | /* Log the connection. */ |
1425 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
8efc0c15 | 1426 | |
aa3378df | 1427 | /* |
1428 | * We don\'t want to listen forever unless the other side | |
1429 | * successfully authenticates itself. So we set up an alarm which is | |
1430 | * cleared after successful authentication. A limit of zero | |
1431 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1432 | * mode; it is just annoying to have the server exit just when you | |
1433 | * are about to discover the bug. | |
1434 | */ | |
5260325f | 1435 | signal(SIGALRM, grace_alarm_handler); |
1436 | if (!debug_flag) | |
1437 | alarm(options.login_grace_time); | |
1438 | ||
7368a6c8 | 1439 | sshd_exchange_identification(sock_in, sock_out); |
aa3378df | 1440 | /* |
6ffc9c88 | 1441 | * Check that the connection comes from a privileged port. |
c242fc96 | 1442 | * Rhosts-Authentication only makes sense from privileged |
aa3378df | 1443 | * programs. Of course, if the intruder has root access on his local |
1444 | * machine, he can connect from any port. So do not use these | |
1445 | * authentication methods from machines that you do not trust. | |
1446 | */ | |
44b1a8e5 | 1447 | if (options.rhosts_authentication && |
1448 | (remote_port >= IPPORT_RESERVED || | |
1449 | remote_port < IPPORT_RESERVED / 2)) { | |
6ffc9c88 | 1450 | debug("Rhosts Authentication disabled, " |
9ae3f727 | 1451 | "originating port %d not trusted.", remote_port); |
5260325f | 1452 | options.rhosts_authentication = 0; |
5260325f | 1453 | } |
ced49be2 | 1454 | #if defined(KRB4) && !defined(KRB5) |
48e671d5 | 1455 | if (!packet_connection_is_ipv4() && |
1456 | options.kerberos_authentication) { | |
1457 | debug("Kerberos Authentication disabled, only available for IPv4."); | |
1458 | options.kerberos_authentication = 0; | |
1459 | } | |
ced49be2 | 1460 | #endif /* KRB4 && !KRB5 */ |
abf1f107 | 1461 | #ifdef AFS |
1462 | /* If machine has AFS, set process authentication group. */ | |
1463 | if (k_hasafs()) { | |
1464 | k_setpag(); | |
1465 | k_unlog(); | |
1466 | } | |
1467 | #endif /* AFS */ | |
48e671d5 | 1468 | |
5260325f | 1469 | packet_set_nonblocking(); |
1470 | ||
324bf712 | 1471 | if (use_privsep) |
1472 | if ((authctxt = privsep_preauth()) != NULL) | |
1473 | goto authenticated; | |
1853d1ef | 1474 | |
7b2ea3a1 | 1475 | /* perform the key exchange */ |
7b2ea3a1 | 1476 | /* authenticate user and start session */ |
e78a59f5 | 1477 | if (compat20) { |
1478 | do_ssh2_kex(); | |
1b34c1b3 | 1479 | authctxt = do_authentication2(); |
e78a59f5 | 1480 | } else { |
1481 | do_ssh1_kex(); | |
1b34c1b3 | 1482 | authctxt = do_authentication(); |
e78a59f5 | 1483 | } |
324bf712 | 1484 | /* |
1485 | * If we use privilege separation, the unprivileged child transfers | |
1486 | * the current keystate and exits | |
1487 | */ | |
1488 | if (use_privsep) { | |
b5a28cbc | 1489 | mm_send_keystate(pmonitor); |
1853d1ef | 1490 | exit(0); |
324bf712 | 1491 | } |
1853d1ef | 1492 | |
1493 | authenticated: | |
762715ce | 1494 | /* |
1853d1ef | 1495 | * In privilege separation, we fork another child and prepare |
1496 | * file descriptor passing. | |
1497 | */ | |
1498 | if (use_privsep) { | |
324bf712 | 1499 | privsep_postauth(authctxt); |
1500 | /* the monitor process [priv] will not return */ | |
1853d1ef | 1501 | if (!compat20) |
1502 | destroy_sensitive_data(); | |
1503 | } | |
1b34c1b3 | 1504 | |
1505 | /* Perform session preparation. */ | |
1506 | do_authenticated(authctxt); | |
1507 | ||
63284fbb | 1508 | /* The connection has been terminated. */ |
1509 | verbose("Closing connection to %.100s", remote_ip); | |
8efc0c15 | 1510 | |
d94aa2ae | 1511 | #ifdef USE_PAM |
a5c9cd31 | 1512 | finish_pam(); |
d94aa2ae | 1513 | #endif /* USE_PAM */ |
8efc0c15 | 1514 | |
5260325f | 1515 | packet_close(); |
1853d1ef | 1516 | |
1517 | if (use_privsep) | |
1518 | mm_terminate(); | |
1519 | ||
5260325f | 1520 | exit(0); |
1521 | } | |
8efc0c15 | 1522 | |
4f08e98d | 1523 | /* |
1524 | * Decrypt session_key_int using our private server key and private host key | |
1525 | * (key with larger modulus first). | |
1526 | */ | |
1853d1ef | 1527 | int |
4f08e98d | 1528 | ssh1_session_key(BIGNUM *session_key_int) |
1529 | { | |
1530 | int rsafail = 0; | |
1531 | ||
1532 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { | |
1533 | /* Server key has bigger modulus. */ | |
1534 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < | |
1535 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1536 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1537 | get_remote_ipaddr(), | |
1538 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1539 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1540 | SSH_KEY_BITS_RESERVED); | |
1541 | } | |
1542 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1543 | sensitive_data.server_key->rsa) <= 0) | |
1544 | rsafail++; | |
1545 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1546 | sensitive_data.ssh1_host_key->rsa) <= 0) | |
1547 | rsafail++; | |
1548 | } else { | |
1549 | /* Host key has bigger modulus (or they are equal). */ | |
1550 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < | |
1551 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1552 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1553 | get_remote_ipaddr(), | |
1554 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1555 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1556 | SSH_KEY_BITS_RESERVED); | |
1557 | } | |
1558 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1559 | sensitive_data.ssh1_host_key->rsa) < 0) | |
1560 | rsafail++; | |
1561 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1562 | sensitive_data.server_key->rsa) < 0) | |
1563 | rsafail++; | |
1564 | } | |
1565 | return (rsafail); | |
1566 | } | |
5260325f | 1567 | /* |
7b2ea3a1 | 1568 | * SSH1 key exchange |
5260325f | 1569 | */ |
396c147e | 1570 | static void |
1e3b8b07 | 1571 | do_ssh1_kex(void) |
8efc0c15 | 1572 | { |
5260325f | 1573 | int i, len; |
46aa2d1f | 1574 | int rsafail = 0; |
5260325f | 1575 | BIGNUM *session_key_int; |
1e3b8b07 | 1576 | u_char session_key[SSH_SESSION_KEY_LENGTH]; |
1577 | u_char cookie[8]; | |
1578 | u_int cipher_type, auth_mask, protocol_flags; | |
5260325f | 1579 | u_int32_t rand = 0; |
1580 | ||
aa3378df | 1581 | /* |
1582 | * Generate check bytes that the client must send back in the user | |
1583 | * packet in order for it to be accepted; this is used to defy ip | |
1584 | * spoofing attacks. Note that this only works against somebody | |
1585 | * doing IP spoofing from a remote machine; any machine on the local | |
1586 | * network can still see outgoing packets and catch the random | |
1587 | * cookie. This only affects rhosts authentication, and this is one | |
1588 | * of the reasons why it is inherently insecure. | |
1589 | */ | |
5260325f | 1590 | for (i = 0; i < 8; i++) { |
1591 | if (i % 4 == 0) | |
1592 | rand = arc4random(); | |
7b2ea3a1 | 1593 | cookie[i] = rand & 0xff; |
5260325f | 1594 | rand >>= 8; |
1595 | } | |
1596 | ||
aa3378df | 1597 | /* |
1598 | * Send our public key. We include in the packet 64 bits of random | |
1599 | * data that must be matched in the reply in order to prevent IP | |
1600 | * spoofing. | |
1601 | */ | |
5260325f | 1602 | packet_start(SSH_SMSG_PUBLIC_KEY); |
1603 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1604 | packet_put_char(cookie[i]); |
5260325f | 1605 | |
1606 | /* Store our public server RSA key. */ | |
fa08c86b | 1607 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); |
1608 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1609 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
5260325f | 1610 | |
1611 | /* Store our public host RSA key. */ | |
fa08c86b | 1612 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); |
1613 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1614 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
5260325f | 1615 | |
1616 | /* Put protocol flags. */ | |
1617 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1618 | ||
1619 | /* Declare which ciphers we support. */ | |
94ec8c6b | 1620 | packet_put_int(cipher_mask_ssh1(0)); |
5260325f | 1621 | |
1622 | /* Declare supported authentication types. */ | |
1623 | auth_mask = 0; | |
1624 | if (options.rhosts_authentication) | |
1625 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
1626 | if (options.rhosts_rsa_authentication) | |
1627 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1628 | if (options.rsa_authentication) | |
1629 | auth_mask |= 1 << SSH_AUTH_RSA; | |
ced49be2 | 1630 | #if defined(KRB4) || defined(KRB5) |
5260325f | 1631 | if (options.kerberos_authentication) |
1632 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
8efc0c15 | 1633 | #endif |
ced49be2 | 1634 | #if defined(AFS) || defined(KRB5) |
5260325f | 1635 | if (options.kerberos_tgt_passing) |
1636 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
ced49be2 | 1637 | #endif |
1638 | #ifdef AFS | |
5260325f | 1639 | if (options.afs_token_passing) |
1640 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
8efc0c15 | 1641 | #endif |
5ba55ada | 1642 | if (options.challenge_response_authentication == 1) |
5260325f | 1643 | auth_mask |= 1 << SSH_AUTH_TIS; |
5260325f | 1644 | if (options.password_authentication) |
1645 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1646 | packet_put_int(auth_mask); | |
1647 | ||
1648 | /* Send the packet and wait for it to be sent. */ | |
1649 | packet_send(); | |
1650 | packet_write_wait(); | |
1651 | ||
fa08c86b | 1652 | debug("Sent %d bit server key and %d bit host key.", |
1653 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1654 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
5260325f | 1655 | |
1656 | /* Read clients reply (cipher type and session key). */ | |
54a5250f | 1657 | packet_read_expect(SSH_CMSG_SESSION_KEY); |
5260325f | 1658 | |
2d86a6cc | 1659 | /* Get cipher type and check whether we accept this. */ |
5260325f | 1660 | cipher_type = packet_get_char(); |
1661 | ||
94ec8c6b | 1662 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) |
2d86a6cc | 1663 | packet_disconnect("Warning: client selects unsupported cipher."); |
1664 | ||
5260325f | 1665 | /* Get check bytes from the packet. These must match those we |
1666 | sent earlier with the public key packet. */ | |
1667 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1668 | if (cookie[i] != packet_get_char()) |
5260325f | 1669 | packet_disconnect("IP Spoofing check bytes do not match."); |
1670 | ||
1671 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1672 | ||
1673 | /* Get the encrypted integer. */ | |
b775c6f2 | 1674 | if ((session_key_int = BN_new()) == NULL) |
1675 | fatal("do_ssh1_kex: BN_new failed"); | |
20b279e6 | 1676 | packet_get_bignum(session_key_int); |
5260325f | 1677 | |
5260325f | 1678 | protocol_flags = packet_get_int(); |
1679 | packet_set_protocol_flags(protocol_flags); | |
95500969 | 1680 | packet_check_eom(); |
5260325f | 1681 | |
4f08e98d | 1682 | /* Decrypt session_key_int using host/server keys */ |
1853d1ef | 1683 | rsafail = PRIVSEP(ssh1_session_key(session_key_int)); |
1684 | ||
aa3378df | 1685 | /* |
1686 | * Extract session key from the decrypted integer. The key is in the | |
1687 | * least significant 256 bits of the integer; the first byte of the | |
1688 | * key is in the highest bits. | |
1689 | */ | |
46aa2d1f | 1690 | if (!rsafail) { |
1691 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
1692 | len = BN_num_bytes(session_key_int); | |
1693 | if (len < 0 || len > sizeof(session_key)) { | |
1694 | error("do_connection: bad session key len from %s: " | |
5ca51e19 | 1695 | "session_key_int %d > sizeof(session_key) %lu", |
1696 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); | |
46aa2d1f | 1697 | rsafail++; |
1698 | } else { | |
1699 | memset(session_key, 0, sizeof(session_key)); | |
1700 | BN_bn2bin(session_key_int, | |
1701 | session_key + sizeof(session_key) - len); | |
00be5382 | 1702 | |
1703 | compute_session_id(session_id, cookie, | |
1704 | sensitive_data.ssh1_host_key->rsa->n, | |
1705 | sensitive_data.server_key->rsa->n); | |
1706 | /* | |
1707 | * Xor the first 16 bytes of the session key with the | |
1708 | * session id. | |
1709 | */ | |
1710 | for (i = 0; i < 16; i++) | |
1711 | session_key[i] ^= session_id[i]; | |
46aa2d1f | 1712 | } |
1713 | } | |
1714 | if (rsafail) { | |
00be5382 | 1715 | int bytes = BN_num_bytes(session_key_int); |
f6b1ba8f | 1716 | u_char *buf = xmalloc(bytes); |
00be5382 | 1717 | MD5_CTX md; |
1718 | ||
46aa2d1f | 1719 | log("do_connection: generating a fake encryption key"); |
00be5382 | 1720 | BN_bn2bin(session_key_int, buf); |
1721 | MD5_Init(&md); | |
1722 | MD5_Update(&md, buf, bytes); | |
1723 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1724 | MD5_Final(session_key, &md); | |
1725 | MD5_Init(&md); | |
1726 | MD5_Update(&md, session_key, 16); | |
1727 | MD5_Update(&md, buf, bytes); | |
1728 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1729 | MD5_Final(session_key + 16, &md); | |
1730 | memset(buf, 0, bytes); | |
1731 | xfree(buf); | |
0572fe75 | 1732 | for (i = 0; i < 16; i++) |
1733 | session_id[i] = session_key[i] ^ session_key[i + 16]; | |
46aa2d1f | 1734 | } |
1853d1ef | 1735 | /* Destroy the private and public keys. No longer. */ |
63284fbb | 1736 | destroy_sensitive_data(); |
00be5382 | 1737 | |
1853d1ef | 1738 | if (use_privsep) |
1739 | mm_ssh1_session_id(session_id); | |
1740 | ||
7b2ea3a1 | 1741 | /* Destroy the decrypted integer. It is no longer needed. */ |
1742 | BN_clear_free(session_key_int); | |
1743 | ||
5260325f | 1744 | /* Set the session key. From this on all communications will be encrypted. */ |
1745 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1746 | ||
1747 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1748 | memset(session_key, 0, sizeof(session_key)); | |
1749 | ||
1750 | debug("Received session key; encryption turned on."); | |
1751 | ||
c242fc96 | 1752 | /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ |
5260325f | 1753 | packet_start(SSH_SMSG_SUCCESS); |
1754 | packet_send(); | |
1755 | packet_write_wait(); | |
5260325f | 1756 | } |
e78a59f5 | 1757 | |
1758 | /* | |
1759 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1760 | */ | |
396c147e | 1761 | static void |
1e3b8b07 | 1762 | do_ssh2_kex(void) |
e78a59f5 | 1763 | { |
e78a59f5 | 1764 | Kex *kex; |
e78a59f5 | 1765 | |
a8be9f80 | 1766 | if (options.ciphers != NULL) { |
6ae2364d | 1767 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
a8be9f80 | 1768 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
1769 | } | |
1ad64a93 | 1770 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
1771 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); | |
1772 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
1773 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); | |
1774 | ||
b2552997 | 1775 | if (options.macs != NULL) { |
1776 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
1777 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
1778 | } | |
636f76ca | 1779 | if (!options.compression) { |
1780 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
1781 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
1782 | } | |
fa08c86b | 1783 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
1784 | ||
7a37c112 | 1785 | /* start key exchange */ |
d8ee838b | 1786 | kex = kex_setup(myproposal); |
a5c9ffdb | 1787 | kex->server = 1; |
1788 | kex->client_version_string=client_version_string; | |
1789 | kex->server_version_string=server_version_string; | |
1790 | kex->load_host_key=&get_hostkey_by_type; | |
1853d1ef | 1791 | kex->host_key_index=&get_hostkey_index; |
94ec8c6b | 1792 | |
7a37c112 | 1793 | xxx_kex = kex; |
1794 | ||
c422989b | 1795 | dispatch_run(DISPATCH_BLOCK, &kex->done, kex); |
94ec8c6b | 1796 | |
d1ac6175 | 1797 | session_id2 = kex->session_id; |
1798 | session_id2_len = kex->session_id_len; | |
1799 | ||
94ec8c6b | 1800 | #ifdef DEBUG_KEXDH |
1801 | /* send 1st encrypted/maced/compressed message */ | |
1802 | packet_start(SSH2_MSG_IGNORE); | |
1803 | packet_put_cstring("markus"); | |
1804 | packet_send(); | |
1805 | packet_write_wait(); | |
1806 | #endif | |
a5c9ffdb | 1807 | debug("KEX done"); |
e78a59f5 | 1808 | } |