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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" | |
6ded293b | 45 | RCSID("$OpenBSD: sshd.c,v 1.253 2002/06/28 23:05:06 deraadt Exp $"); |
8efc0c15 | 46 | |
42f11eb2 | 47 | #include <openssl/dh.h> |
48 | #include <openssl/bn.h> | |
436c347c | 49 | #include <openssl/md5.h> |
1853d1ef | 50 | #include <openssl/rand.h> |
6e879cb4 | 51 | #ifdef HAVE_SECUREWARE |
52 | #include <sys/security.h> | |
53 | #include <prot.h> | |
54 | #endif | |
42f11eb2 | 55 | |
56 | #include "ssh.h" | |
57 | #include "ssh1.h" | |
58 | #include "ssh2.h" | |
8efc0c15 | 59 | #include "xmalloc.h" |
60 | #include "rsa.h" | |
1729c161 | 61 | #include "sshpty.h" |
8efc0c15 | 62 | #include "packet.h" |
8efc0c15 | 63 | #include "mpaux.h" |
42f11eb2 | 64 | #include "log.h" |
8efc0c15 | 65 | #include "servconf.h" |
66 | #include "uidswap.h" | |
67 | #include "compat.h" | |
7368a6c8 | 68 | #include "buffer.h" |
42f11eb2 | 69 | #include "cipher.h" |
e78a59f5 | 70 | #include "kex.h" |
7368a6c8 | 71 | #include "key.h" |
94ec8c6b | 72 | #include "dh.h" |
e78a59f5 | 73 | #include "myproposal.h" |
a306f2dd | 74 | #include "authfile.h" |
42f11eb2 | 75 | #include "pathnames.h" |
76 | #include "atomicio.h" | |
77 | #include "canohost.h" | |
78 | #include "auth.h" | |
79 | #include "misc.h" | |
a5c9ffdb | 80 | #include "dispatch.h" |
e4d7f734 | 81 | #include "channels.h" |
1b34c1b3 | 82 | #include "session.h" |
1853d1ef | 83 | #include "monitor_mm.h" |
84 | #include "monitor.h" | |
85 | #include "monitor_wrap.h" | |
86 | #include "monitor_fdpass.h" | |
8efc0c15 | 87 | |
88 | #ifdef LIBWRAP | |
89 | #include <tcpd.h> | |
90 | #include <syslog.h> | |
91 | int allow_severity = LOG_INFO; | |
92 | int deny_severity = LOG_WARNING; | |
93 | #endif /* LIBWRAP */ | |
94 | ||
95 | #ifndef O_NOCTTY | |
96 | #define O_NOCTTY 0 | |
97 | #endif | |
98 | ||
260d427b | 99 | #ifdef HAVE___PROGNAME |
100 | extern char *__progname; | |
101 | #else | |
102 | char *__progname; | |
103 | #endif | |
104 | ||
8efc0c15 | 105 | /* Server configuration options. */ |
106 | ServerOptions options; | |
107 | ||
108 | /* Name of the server configuration file. */ | |
42f11eb2 | 109 | char *config_file_name = _PATH_SERVER_CONFIG_FILE; |
8efc0c15 | 110 | |
6ae2364d | 111 | /* |
48e671d5 | 112 | * Flag indicating whether IPv4 or IPv6. This can be set on the command line. |
113 | * Default value is AF_UNSPEC means both IPv4 and IPv6. | |
114 | */ | |
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]; | |
6ded293b | 533 | gid_t gidset[1]; |
2ea6de2b | 534 | struct passwd *pw; |
e424e241 | 535 | int i; |
1853d1ef | 536 | |
537 | /* Enable challenge-response authentication for privilege separation */ | |
538 | privsep_challenge_enable(); | |
539 | ||
540 | for (i = 0; i < 256; i++) | |
541 | rand[i] = arc4random(); | |
542 | RAND_seed(rand, sizeof(rand)); | |
543 | ||
544 | /* Demote the private keys to public keys. */ | |
545 | demote_sensitive_data(); | |
546 | ||
2ea6de2b | 547 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) |
cdc4fc39 | 548 | fatal("Privilege separation user %s does not exist", |
549 | SSH_PRIVSEP_USER); | |
2ea6de2b | 550 | memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); |
551 | endpwent(); | |
552 | ||
1853d1ef | 553 | /* Change our root directory*/ |
1c352e97 | 554 | if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) |
555 | fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, | |
556 | strerror(errno)); | |
1853d1ef | 557 | if (chdir("/") == -1) |
edfb66cb | 558 | fatal("chdir(\"/\"): %s", strerror(errno)); |
762715ce | 559 | |
1853d1ef | 560 | /* Drop our privileges */ |
2ea6de2b | 561 | debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, |
562 | (u_int)pw->pw_gid); | |
87809a1f | 563 | #if 0 |
564 | /* XXX not ready, to heavy after chroot */ | |
2ea6de2b | 565 | do_setusercontext(pw); |
87809a1f | 566 | #else |
567 | gidset[0] = pw->pw_gid; | |
568 | if (setgid(pw->pw_gid) < 0) | |
569 | fatal("setgid failed for %u", pw->pw_gid ); | |
570 | if (setgroups(1, gidset) < 0) | |
571 | fatal("setgroups: %.100s", strerror(errno)); | |
572 | permanently_set_uid(pw); | |
573 | #endif | |
1853d1ef | 574 | } |
575 | ||
324bf712 | 576 | static Authctxt* |
577 | privsep_preauth(void) | |
1853d1ef | 578 | { |
324bf712 | 579 | Authctxt *authctxt = NULL; |
1853d1ef | 580 | int status; |
324bf712 | 581 | pid_t pid; |
1853d1ef | 582 | |
324bf712 | 583 | /* Set up unprivileged child process to deal with network data */ |
b5a28cbc | 584 | pmonitor = monitor_init(); |
324bf712 | 585 | /* Store a pointer to the kex for later rekeying */ |
b5a28cbc | 586 | pmonitor->m_pkex = &xxx_kex; |
324bf712 | 587 | |
588 | pid = fork(); | |
589 | if (pid == -1) { | |
590 | fatal("fork of unprivileged child failed"); | |
591 | } else if (pid != 0) { | |
c457707e | 592 | debug2("Network child is on pid %ld", (long)pid); |
324bf712 | 593 | |
b5a28cbc | 594 | close(pmonitor->m_recvfd); |
595 | authctxt = monitor_child_preauth(pmonitor); | |
596 | close(pmonitor->m_sendfd); | |
324bf712 | 597 | |
598 | /* Sync memory */ | |
b5a28cbc | 599 | monitor_sync(pmonitor); |
324bf712 | 600 | |
601 | /* Wait for the child's exit status */ | |
8c38e88b | 602 | while (waitpid(pid, &status, 0) < 0) |
603 | if (errno != EINTR) | |
604 | break; | |
324bf712 | 605 | return (authctxt); |
606 | } else { | |
607 | /* child */ | |
608 | ||
b5a28cbc | 609 | close(pmonitor->m_sendfd); |
324bf712 | 610 | |
611 | /* Demote the child */ | |
612 | if (getuid() == 0 || geteuid() == 0) | |
613 | privsep_preauth_child(); | |
47c36e5b | 614 | setproctitle("%s", "[net]"); |
324bf712 | 615 | } |
616 | return (NULL); | |
617 | } | |
618 | ||
619 | static void | |
620 | privsep_postauth(Authctxt *authctxt) | |
621 | { | |
622 | extern Authctxt *x_authctxt; | |
1853d1ef | 623 | |
624 | /* XXX - Remote port forwarding */ | |
625 | x_authctxt = authctxt; | |
626 | ||
d170feb1 | 627 | #ifdef BROKEN_FD_PASSING |
628 | if (1) { | |
629 | #else | |
1853d1ef | 630 | if (authctxt->pw->pw_uid == 0 || options.use_login) { |
d170feb1 | 631 | #endif |
1853d1ef | 632 | /* File descriptor passing is broken or root login */ |
b5a28cbc | 633 | monitor_apply_keystate(pmonitor); |
1853d1ef | 634 | use_privsep = 0; |
635 | return; | |
636 | } | |
762715ce | 637 | |
1853d1ef | 638 | /* Authentication complete */ |
639 | alarm(0); | |
640 | if (startup_pipe != -1) { | |
641 | close(startup_pipe); | |
642 | startup_pipe = -1; | |
643 | } | |
644 | ||
645 | /* New socket pair */ | |
b5a28cbc | 646 | monitor_reinit(pmonitor); |
1853d1ef | 647 | |
b5a28cbc | 648 | pmonitor->m_pid = fork(); |
649 | if (pmonitor->m_pid == -1) | |
1853d1ef | 650 | fatal("fork of unprivileged child failed"); |
b5a28cbc | 651 | else if (pmonitor->m_pid != 0) { |
c457707e | 652 | debug2("User child is on pid %ld", (long)pmonitor->m_pid); |
b5a28cbc | 653 | close(pmonitor->m_recvfd); |
654 | monitor_child_postauth(pmonitor); | |
1853d1ef | 655 | |
656 | /* NEVERREACHED */ | |
657 | exit(0); | |
658 | } | |
659 | ||
b5a28cbc | 660 | close(pmonitor->m_sendfd); |
1853d1ef | 661 | |
662 | /* Demote the private keys to public keys. */ | |
663 | demote_sensitive_data(); | |
664 | ||
665 | /* Drop privileges */ | |
666 | do_setusercontext(authctxt->pw); | |
667 | ||
668 | /* It is safe now to apply the key state */ | |
b5a28cbc | 669 | monitor_apply_keystate(pmonitor); |
1853d1ef | 670 | } |
671 | ||
396c147e | 672 | static char * |
fa08c86b | 673 | list_hostkey_types(void) |
674 | { | |
3469eac4 | 675 | Buffer b; |
676 | char *p; | |
fa08c86b | 677 | int i; |
3469eac4 | 678 | |
679 | buffer_init(&b); | |
184eed6a | 680 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 681 | Key *key = sensitive_data.host_keys[i]; |
682 | if (key == NULL) | |
683 | continue; | |
6aacefa7 | 684 | switch (key->type) { |
fa08c86b | 685 | case KEY_RSA: |
686 | case KEY_DSA: | |
3469eac4 | 687 | if (buffer_len(&b) > 0) |
688 | buffer_append(&b, ",", 1); | |
689 | p = key_ssh_name(key); | |
690 | buffer_append(&b, p, strlen(p)); | |
fa08c86b | 691 | break; |
692 | } | |
693 | } | |
3469eac4 | 694 | buffer_append(&b, "\0", 1); |
695 | p = xstrdup(buffer_ptr(&b)); | |
696 | buffer_free(&b); | |
697 | debug("list_hostkey_types: %s", p); | |
698 | return p; | |
fa08c86b | 699 | } |
700 | ||
1853d1ef | 701 | Key * |
fa08c86b | 702 | get_hostkey_by_type(int type) |
703 | { | |
704 | int i; | |
e424e241 | 705 | |
184eed6a | 706 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 707 | Key *key = sensitive_data.host_keys[i]; |
708 | if (key != NULL && key->type == type) | |
709 | return key; | |
710 | } | |
711 | return NULL; | |
7368a6c8 | 712 | } |
713 | ||
1853d1ef | 714 | Key * |
715 | get_hostkey_by_index(int ind) | |
716 | { | |
717 | if (ind < 0 || ind >= options.num_host_key_files) | |
718 | return (NULL); | |
719 | return (sensitive_data.host_keys[ind]); | |
720 | } | |
721 | ||
722 | int | |
723 | get_hostkey_index(Key *key) | |
724 | { | |
725 | int i; | |
e424e241 | 726 | |
1853d1ef | 727 | for (i = 0; i < options.num_host_key_files; i++) { |
728 | if (key == sensitive_data.host_keys[i]) | |
729 | return (i); | |
730 | } | |
731 | return (-1); | |
732 | } | |
733 | ||
c345cf9d | 734 | /* |
735 | * returns 1 if connection should be dropped, 0 otherwise. | |
736 | * dropping starts at connection #max_startups_begin with a probability | |
737 | * of (max_startups_rate/100). the probability increases linearly until | |
738 | * all connections are dropped for startups > max_startups | |
739 | */ | |
396c147e | 740 | static int |
c345cf9d | 741 | drop_connection(int startups) |
742 | { | |
743 | double p, r; | |
744 | ||
745 | if (startups < options.max_startups_begin) | |
746 | return 0; | |
747 | if (startups >= options.max_startups) | |
748 | return 1; | |
749 | if (options.max_startups_rate == 100) | |
750 | return 1; | |
751 | ||
752 | p = 100 - options.max_startups_rate; | |
753 | p *= startups - options.max_startups_begin; | |
754 | p /= (double) (options.max_startups - options.max_startups_begin); | |
755 | p += options.max_startups_rate; | |
756 | p /= 100.0; | |
757 | r = arc4random() / (double) UINT_MAX; | |
758 | ||
759 | debug("drop_connection: p %g, r %g", p, r); | |
760 | return (r < p) ? 1 : 0; | |
761 | } | |
762 | ||
2717fa0f | 763 | static void |
764 | usage(void) | |
765 | { | |
766 | fprintf(stderr, "sshd version %s\n", SSH_VERSION); | |
767 | fprintf(stderr, "Usage: %s [options]\n", __progname); | |
768 | fprintf(stderr, "Options:\n"); | |
769 | fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE); | |
770 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); | |
771 | fprintf(stderr, " -i Started from inetd\n"); | |
772 | fprintf(stderr, " -D Do not fork into daemon mode\n"); | |
773 | fprintf(stderr, " -t Only test configuration file and keys\n"); | |
774 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
775 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
776 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
777 | fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n"); | |
778 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
779 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
780 | _PATH_HOST_KEY_FILE); | |
781 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); | |
782 | fprintf(stderr, " -4 Use IPv4 only\n"); | |
783 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
784 | fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n"); | |
785 | exit(1); | |
786 | } | |
787 | ||
5260325f | 788 | /* |
789 | * Main program for the daemon. | |
790 | */ | |
8efc0c15 | 791 | int |
792 | main(int ac, char **av) | |
793 | { | |
5260325f | 794 | extern char *optarg; |
795 | extern int optind; | |
089fbbd2 | 796 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; |
9da5c3c9 | 797 | pid_t pid; |
48e671d5 | 798 | socklen_t fromlen; |
48e671d5 | 799 | fd_set *fdset; |
800 | struct sockaddr_storage from; | |
5260325f | 801 | const char *remote_ip; |
802 | int remote_port; | |
5260325f | 803 | FILE *f; |
804 | struct linger linger; | |
48e671d5 | 805 | struct addrinfo *ai; |
806 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
807 | int listen_sock, maxfd; | |
089fbbd2 | 808 | int startup_p[2]; |
809 | int startups = 0; | |
1b34c1b3 | 810 | Authctxt *authctxt; |
aeaa3d9e | 811 | Key *key; |
59c97189 | 812 | int ret, key_used = 0; |
5260325f | 813 | |
6e879cb4 | 814 | #ifdef HAVE_SECUREWARE |
815 | (void)set_auth_parameters(ac, av); | |
816 | #endif | |
260d427b | 817 | __progname = get_progname(av[0]); |
264dce47 | 818 | init_rng(); |
819 | ||
1fe6a48f | 820 | /* Save argv. */ |
4d33e531 | 821 | saved_argc = ac; |
5260325f | 822 | saved_argv = av; |
5260325f | 823 | |
824 | /* Initialize configuration options to their default values. */ | |
825 | initialize_server_options(&options); | |
826 | ||
827 | /* Parse command-line arguments. */ | |
2717fa0f | 828 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:o:dDeiqtQ46")) != -1) { |
5260325f | 829 | switch (opt) { |
48e671d5 | 830 | case '4': |
831 | IPv4or6 = AF_INET; | |
832 | break; | |
833 | case '6': | |
834 | IPv4or6 = AF_INET6; | |
835 | break; | |
5260325f | 836 | case 'f': |
837 | config_file_name = optarg; | |
838 | break; | |
839 | case 'd': | |
bcbf86ec | 840 | if (0 == debug_flag) { |
841 | debug_flag = 1; | |
842 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
843 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) { | |
844 | options.log_level++; | |
845 | } else { | |
846 | fprintf(stderr, "Too high debugging level.\n"); | |
847 | exit(1); | |
848 | } | |
5260325f | 849 | break; |
0b6fbf03 | 850 | case 'D': |
851 | no_daemon_flag = 1; | |
852 | break; | |
ff14faf1 | 853 | case 'e': |
854 | log_stderr = 1; | |
855 | break; | |
5260325f | 856 | case 'i': |
857 | inetd_flag = 1; | |
858 | break; | |
859 | case 'Q': | |
9bd5b720 | 860 | /* ignored */ |
5260325f | 861 | break; |
862 | case 'q': | |
863 | options.log_level = SYSLOG_LEVEL_QUIET; | |
864 | break; | |
865 | case 'b': | |
866 | options.server_key_bits = atoi(optarg); | |
867 | break; | |
868 | case 'p': | |
48e671d5 | 869 | options.ports_from_cmdline = 1; |
bcbf86ec | 870 | if (options.num_ports >= MAX_PORTS) { |
871 | fprintf(stderr, "too many ports.\n"); | |
872 | exit(1); | |
873 | } | |
2d2a2c65 | 874 | options.ports[options.num_ports++] = a2port(optarg); |
875 | if (options.ports[options.num_ports-1] == 0) { | |
876 | fprintf(stderr, "Bad port number.\n"); | |
877 | exit(1); | |
878 | } | |
5260325f | 879 | break; |
880 | case 'g': | |
e2b1fb42 | 881 | if ((options.login_grace_time = convtime(optarg)) == -1) { |
882 | fprintf(stderr, "Invalid login grace time.\n"); | |
883 | exit(1); | |
884 | } | |
5260325f | 885 | break; |
886 | case 'k': | |
e2b1fb42 | 887 | if ((options.key_regeneration_time = convtime(optarg)) == -1) { |
888 | fprintf(stderr, "Invalid key regeneration interval.\n"); | |
889 | exit(1); | |
890 | } | |
5260325f | 891 | break; |
892 | case 'h': | |
fa08c86b | 893 | if (options.num_host_key_files >= MAX_HOSTKEYS) { |
894 | fprintf(stderr, "too many host keys.\n"); | |
895 | exit(1); | |
896 | } | |
897 | options.host_key_files[options.num_host_key_files++] = optarg; | |
5260325f | 898 | break; |
899 | case 'V': | |
900 | client_version_string = optarg; | |
901 | /* only makes sense with inetd_flag, i.e. no listen() */ | |
902 | inetd_flag = 1; | |
903 | break; | |
f87f09aa | 904 | case 't': |
905 | test_flag = 1; | |
906 | break; | |
c345cf9d | 907 | case 'u': |
908 | utmp_len = atoi(optarg); | |
4efd85b2 | 909 | if (utmp_len < 0 || utmp_len > MAXHOSTNAMELEN) |
910 | usage(); | |
c345cf9d | 911 | break; |
2717fa0f | 912 | case 'o': |
184eed6a | 913 | if (process_server_config_line(&options, optarg, |
2717fa0f | 914 | "command-line", 0) != 0) |
184eed6a | 915 | exit(1); |
2717fa0f | 916 | break; |
5260325f | 917 | case '?': |
918 | default: | |
2717fa0f | 919 | usage(); |
920 | break; | |
5260325f | 921 | } |
922 | } | |
1a92bd7e | 923 | SSLeay_add_all_algorithms(); |
5e4a7219 | 924 | channel_set_af(IPv4or6); |
5260325f | 925 | |
48e671d5 | 926 | /* |
927 | * Force logging to stderr until we have loaded the private host | |
928 | * key (unless started from inetd) | |
929 | */ | |
1fe6a48f | 930 | log_init(__progname, |
980c9344 | 931 | options.log_level == SYSLOG_LEVEL_NOT_SET ? |
932 | SYSLOG_LEVEL_INFO : options.log_level, | |
933 | options.log_facility == SYSLOG_FACILITY_NOT_SET ? | |
934 | SYSLOG_FACILITY_AUTH : options.log_facility, | |
9bd5b720 | 935 | !inetd_flag); |
48e671d5 | 936 | |
1a23ac2c | 937 | #ifdef _CRAY |
938 | /* Cray can define user privs drop all prives now! | |
939 | * Not needed on PRIV_SU systems! | |
940 | */ | |
941 | drop_cray_privs(); | |
942 | #endif | |
943 | ||
e339aa53 | 944 | seed_rng(); |
945 | ||
5260325f | 946 | /* Read server configuration options from the configuration file. */ |
947 | read_server_config(&options, config_file_name); | |
948 | ||
949 | /* Fill in default values for those options not explicitly set. */ | |
950 | fill_default_server_options(&options); | |
951 | ||
5260325f | 952 | /* Check that there are no remaining arguments. */ |
953 | if (optind < ac) { | |
954 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
955 | exit(1); | |
8efc0c15 | 956 | } |
5260325f | 957 | |
958 | debug("sshd version %.100s", SSH_VERSION); | |
959 | ||
fa08c86b | 960 | /* load private host keys */ |
961 | sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*)); | |
184eed6a | 962 | for (i = 0; i < options.num_host_key_files; i++) |
1e3b8b07 | 963 | sensitive_data.host_keys[i] = NULL; |
fa08c86b | 964 | sensitive_data.server_key = NULL; |
965 | sensitive_data.ssh1_host_key = NULL; | |
966 | sensitive_data.have_ssh1_key = 0; | |
967 | sensitive_data.have_ssh2_key = 0; | |
a306f2dd | 968 | |
184eed6a | 969 | for (i = 0; i < options.num_host_key_files; i++) { |
aeaa3d9e | 970 | key = key_load_private(options.host_key_files[i], "", NULL); |
971 | sensitive_data.host_keys[i] = key; | |
fa08c86b | 972 | if (key == NULL) { |
58cfa257 | 973 | error("Could not load host key: %s", |
974 | options.host_key_files[i]); | |
aeaa3d9e | 975 | sensitive_data.host_keys[i] = NULL; |
fa08c86b | 976 | continue; |
a306f2dd | 977 | } |
6aacefa7 | 978 | switch (key->type) { |
fa08c86b | 979 | case KEY_RSA1: |
980 | sensitive_data.ssh1_host_key = key; | |
981 | sensitive_data.have_ssh1_key = 1; | |
982 | break; | |
983 | case KEY_RSA: | |
984 | case KEY_DSA: | |
985 | sensitive_data.have_ssh2_key = 1; | |
986 | break; | |
a306f2dd | 987 | } |
aeaa3d9e | 988 | debug("private host key: #%d type %d %s", i, key->type, |
989 | key_type(key)); | |
fa08c86b | 990 | } |
991 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
992 | log("Disabling protocol version 1. Could not load host key"); | |
993 | options.protocol &= ~SSH_PROTO_1; | |
994 | } | |
995 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
996 | log("Disabling protocol version 2. Could not load host key"); | |
997 | options.protocol &= ~SSH_PROTO_2; | |
a306f2dd | 998 | } |
6a416424 | 999 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { |
54b974dc | 1000 | log("sshd: no hostkeys available -- exiting."); |
5260325f | 1001 | exit(1); |
1002 | } | |
5260325f | 1003 | |
a306f2dd | 1004 | /* Check certain values for sanity. */ |
1005 | if (options.protocol & SSH_PROTO_1) { | |
1006 | if (options.server_key_bits < 512 || | |
1007 | options.server_key_bits > 32768) { | |
1008 | fprintf(stderr, "Bad server key size.\n"); | |
1009 | exit(1); | |
1010 | } | |
1011 | /* | |
1012 | * Check that server and host key lengths differ sufficiently. This | |
1013 | * is necessary to make double encryption work with rsaref. Oh, I | |
1014 | * hate software patents. I dont know if this can go? Niels | |
1015 | */ | |
1016 | if (options.server_key_bits > | |
e424e241 | 1017 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - |
1018 | SSH_KEY_BITS_RESERVED && options.server_key_bits < | |
1019 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1020 | SSH_KEY_BITS_RESERVED) { | |
a306f2dd | 1021 | options.server_key_bits = |
e424e241 | 1022 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + |
1023 | SSH_KEY_BITS_RESERVED; | |
a306f2dd | 1024 | debug("Forcing server key to %d bits to make it differ from host key.", |
1025 | options.server_key_bits); | |
1026 | } | |
1027 | } | |
1028 | ||
3cc54fbb | 1029 | if (use_privsep) { |
1030 | struct passwd *pw; | |
1031 | struct stat st; | |
1032 | ||
1033 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
1034 | fatal("Privilege separation user %s does not exist", | |
1035 | SSH_PRIVSEP_USER); | |
1036 | if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || | |
1037 | (S_ISDIR(st.st_mode) == 0)) | |
1038 | fatal("Missing privilege separation directory: %s", | |
1039 | _PATH_PRIVSEP_CHROOT_DIR); | |
b9b82dab | 1040 | |
1041 | #ifdef HAVE_CYGWIN | |
1042 | if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && | |
1043 | (st.st_uid != getuid () || | |
1044 | (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) | |
1045 | #else | |
a56313d7 | 1046 | if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) |
b9b82dab | 1047 | #endif |
a56313d7 | 1048 | fatal("Bad owner or mode for %s", |
1049 | _PATH_PRIVSEP_CHROOT_DIR); | |
3cc54fbb | 1050 | } |
1051 | ||
f87f09aa | 1052 | /* Configuration looks good, so exit if in test mode. */ |
1053 | if (test_flag) | |
1054 | exit(0); | |
1055 | ||
018a5ea3 | 1056 | /* |
1057 | * Clear out any supplemental groups we may have inherited. This | |
1058 | * prevents inadvertent creation of files with bad modes (in the | |
1059 | * portable version at least, it's certainly possible for PAM | |
1060 | * to create a file, and we can't control the code in every | |
1061 | * module which might be used). | |
1062 | */ | |
1063 | if (setgroups(0, NULL) < 0) | |
1064 | debug("setgroups() failed: %.200s", strerror(errno)); | |
1065 | ||
a306f2dd | 1066 | /* Initialize the log (it is reinitialized below in case we forked). */ |
5260325f | 1067 | if (debug_flag && !inetd_flag) |
1068 | log_stderr = 1; | |
1fe6a48f | 1069 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 1070 | |
a306f2dd | 1071 | /* |
1072 | * If not in debugging mode, and not started from inetd, disconnect | |
1073 | * from the controlling terminal, and fork. The original process | |
1074 | * exits. | |
1075 | */ | |
0b6fbf03 | 1076 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { |
8efc0c15 | 1077 | #ifdef TIOCNOTTY |
5260325f | 1078 | int fd; |
8efc0c15 | 1079 | #endif /* TIOCNOTTY */ |
5260325f | 1080 | if (daemon(0, 0) < 0) |
1081 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1082 | ||
1083 | /* Disconnect from the controlling tty. */ | |
8efc0c15 | 1084 | #ifdef TIOCNOTTY |
5ca51e19 | 1085 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); |
5260325f | 1086 | if (fd >= 0) { |
1087 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
1088 | close(fd); | |
1089 | } | |
8efc0c15 | 1090 | #endif /* TIOCNOTTY */ |
8efc0c15 | 1091 | } |
5260325f | 1092 | /* Reinitialize the log (because of the fork above). */ |
1fe6a48f | 1093 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 1094 | |
5260325f | 1095 | /* Initialize the random number generator. */ |
1096 | arc4random_stir(); | |
1097 | ||
1098 | /* Chdir to the root directory so that the current disk can be | |
1099 | unmounted if desired. */ | |
1100 | chdir("/"); | |
184eed6a | 1101 | |
1d3c30db | 1102 | /* ignore SIGPIPE */ |
1103 | signal(SIGPIPE, SIG_IGN); | |
5260325f | 1104 | |
5260325f | 1105 | /* Start listening for a socket, unless started from inetd. */ |
1106 | if (inetd_flag) { | |
ec1f12d3 | 1107 | int s1; |
5260325f | 1108 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ |
ec1f12d3 | 1109 | dup(s1); |
5260325f | 1110 | sock_in = dup(0); |
1111 | sock_out = dup(1); | |
4c8722d9 | 1112 | startup_pipe = -1; |
a306f2dd | 1113 | /* |
1114 | * We intentionally do not close the descriptors 0, 1, and 2 | |
1115 | * as our code for setting the descriptors won\'t work if | |
1116 | * ttyfd happens to be one of those. | |
1117 | */ | |
5260325f | 1118 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); |
fa08c86b | 1119 | if (options.protocol & SSH_PROTO_1) |
cb7bd922 | 1120 | generate_ephemeral_server_key(); |
5260325f | 1121 | } else { |
48e671d5 | 1122 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
1123 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
1124 | continue; | |
1125 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
1126 | fatal("Too many listen sockets. " | |
1127 | "Enlarge MAX_LISTEN_SOCKS"); | |
1128 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
1129 | ntop, sizeof(ntop), strport, sizeof(strport), | |
1130 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
1131 | error("getnameinfo failed"); | |
1132 | continue; | |
1133 | } | |
1134 | /* Create socket for listening. */ | |
1135 | listen_sock = socket(ai->ai_family, SOCK_STREAM, 0); | |
1136 | if (listen_sock < 0) { | |
1137 | /* kernel may not support ipv6 */ | |
1138 | verbose("socket: %.100s", strerror(errno)); | |
1139 | continue; | |
1140 | } | |
1141 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { | |
1142 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
1143 | close(listen_sock); | |
1144 | continue; | |
1145 | } | |
1146 | /* | |
1147 | * Set socket options. We try to make the port | |
1148 | * reusable and have it close as fast as possible | |
1149 | * without waiting in unnecessary wait states on | |
1150 | * close. | |
1151 | */ | |
1152 | setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, | |
db518d9b | 1153 | &on, sizeof(on)); |
48e671d5 | 1154 | linger.l_onoff = 1; |
1155 | linger.l_linger = 5; | |
1156 | setsockopt(listen_sock, SOL_SOCKET, SO_LINGER, | |
db518d9b | 1157 | &linger, sizeof(linger)); |
48e671d5 | 1158 | |
1159 | debug("Bind to port %s on %s.", strport, ntop); | |
1160 | ||
1161 | /* Bind the socket to the desired port. */ | |
32ced054 | 1162 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { |
1163 | if (!ai->ai_next) | |
1164 | error("Bind to port %s on %s failed: %.200s.", | |
1165 | strport, ntop, strerror(errno)); | |
48e671d5 | 1166 | close(listen_sock); |
1167 | continue; | |
1168 | } | |
1169 | listen_socks[num_listen_socks] = listen_sock; | |
1170 | num_listen_socks++; | |
1171 | ||
1172 | /* Start listening on the port. */ | |
1173 | log("Server listening on %s port %s.", ntop, strport); | |
1174 | if (listen(listen_sock, 5) < 0) | |
1175 | fatal("listen: %.100s", strerror(errno)); | |
1176 | ||
5260325f | 1177 | } |
48e671d5 | 1178 | freeaddrinfo(options.listen_addrs); |
1179 | ||
1180 | if (!num_listen_socks) | |
1181 | fatal("Cannot bind any address."); | |
1182 | ||
3aca00a3 | 1183 | if (options.protocol & SSH_PROTO_1) |
1184 | generate_ephemeral_server_key(); | |
1185 | ||
1186 | /* | |
1187 | * Arrange to restart on SIGHUP. The handler needs | |
1188 | * listen_sock. | |
1189 | */ | |
1190 | signal(SIGHUP, sighup_handler); | |
1191 | ||
1192 | signal(SIGTERM, sigterm_handler); | |
1193 | signal(SIGQUIT, sigterm_handler); | |
1194 | ||
1195 | /* Arrange SIGCHLD to be caught. */ | |
1196 | signal(SIGCHLD, main_sigchld_handler); | |
1197 | ||
1198 | /* Write out the pid file after the sigterm handler is setup */ | |
5260325f | 1199 | if (!debug_flag) { |
aa3378df | 1200 | /* |
97fb6912 | 1201 | * Record our pid in /var/run/sshd.pid to make it |
1202 | * easier to kill the correct sshd. We don't want to | |
1203 | * do this before the bind above because the bind will | |
aa3378df | 1204 | * fail if there already is a daemon, and this will |
1205 | * overwrite any old pid in the file. | |
1206 | */ | |
3c62e7eb | 1207 | f = fopen(options.pid_file, "wb"); |
5260325f | 1208 | if (f) { |
c457707e | 1209 | fprintf(f, "%ld\n", (long) getpid()); |
5260325f | 1210 | fclose(f); |
1211 | } | |
8efc0c15 | 1212 | } |
5260325f | 1213 | |
48e671d5 | 1214 | /* setup fd set for listen */ |
089fbbd2 | 1215 | fdset = NULL; |
48e671d5 | 1216 | maxfd = 0; |
1217 | for (i = 0; i < num_listen_socks; i++) | |
1218 | if (listen_socks[i] > maxfd) | |
1219 | maxfd = listen_socks[i]; | |
089fbbd2 | 1220 | /* pipes connected to unauthenticated childs */ |
1221 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
1222 | for (i = 0; i < options.max_startups; i++) | |
1223 | startup_pipes[i] = -1; | |
48e671d5 | 1224 | |
aa3378df | 1225 | /* |
1226 | * Stay listening for connections until the system crashes or | |
1227 | * the daemon is killed with a signal. | |
1228 | */ | |
5260325f | 1229 | for (;;) { |
1230 | if (received_sighup) | |
1231 | sighup_restart(); | |
089fbbd2 | 1232 | if (fdset != NULL) |
1233 | xfree(fdset); | |
b5c334cc | 1234 | fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); |
089fbbd2 | 1235 | fdset = (fd_set *)xmalloc(fdsetsz); |
48e671d5 | 1236 | memset(fdset, 0, fdsetsz); |
089fbbd2 | 1237 | |
48e671d5 | 1238 | for (i = 0; i < num_listen_socks; i++) |
1239 | FD_SET(listen_socks[i], fdset); | |
089fbbd2 | 1240 | for (i = 0; i < options.max_startups; i++) |
1241 | if (startup_pipes[i] != -1) | |
1242 | FD_SET(startup_pipes[i], fdset); | |
1243 | ||
1244 | /* Wait in select until there is a connection. */ | |
59c97189 | 1245 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); |
1246 | if (ret < 0 && errno != EINTR) | |
1247 | error("select: %.100s", strerror(errno)); | |
c9130033 | 1248 | if (received_sigterm) { |
1249 | log("Received signal %d; terminating.", | |
010f9726 | 1250 | (int) received_sigterm); |
c9130033 | 1251 | close_listen_socks(); |
1252 | unlink(options.pid_file); | |
1253 | exit(255); | |
1254 | } | |
59c97189 | 1255 | if (key_used && key_do_regen) { |
cb7bd922 | 1256 | generate_ephemeral_server_key(); |
59c97189 | 1257 | key_used = 0; |
1258 | key_do_regen = 0; | |
48e671d5 | 1259 | } |
59c97189 | 1260 | if (ret < 0) |
1261 | continue; | |
1262 | ||
089fbbd2 | 1263 | for (i = 0; i < options.max_startups; i++) |
1264 | if (startup_pipes[i] != -1 && | |
1265 | FD_ISSET(startup_pipes[i], fdset)) { | |
1266 | /* | |
1267 | * the read end of the pipe is ready | |
1268 | * if the child has closed the pipe | |
8abcdba4 | 1269 | * after successful authentication |
089fbbd2 | 1270 | * or if the child has died |
1271 | */ | |
1272 | close(startup_pipes[i]); | |
1273 | startup_pipes[i] = -1; | |
1274 | startups--; | |
1275 | } | |
48e671d5 | 1276 | for (i = 0; i < num_listen_socks; i++) { |
1277 | if (!FD_ISSET(listen_socks[i], fdset)) | |
5260325f | 1278 | continue; |
089fbbd2 | 1279 | fromlen = sizeof(from); |
1280 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
1281 | &fromlen); | |
1282 | if (newsock < 0) { | |
1283 | if (errno != EINTR && errno != EWOULDBLOCK) | |
1284 | error("accept: %.100s", strerror(errno)); | |
1285 | continue; | |
1286 | } | |
1287 | if (fcntl(newsock, F_SETFL, 0) < 0) { | |
1288 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
5e8948af | 1289 | close(newsock); |
089fbbd2 | 1290 | continue; |
1291 | } | |
c345cf9d | 1292 | if (drop_connection(startups) == 1) { |
1293 | debug("drop connection #%d", startups); | |
089fbbd2 | 1294 | close(newsock); |
1295 | continue; | |
1296 | } | |
1297 | if (pipe(startup_p) == -1) { | |
1298 | close(newsock); | |
1299 | continue; | |
1300 | } | |
1301 | ||
1302 | for (j = 0; j < options.max_startups; j++) | |
1303 | if (startup_pipes[j] == -1) { | |
1304 | startup_pipes[j] = startup_p[0]; | |
1305 | if (maxfd < startup_p[0]) | |
1306 | maxfd = startup_p[0]; | |
1307 | startups++; | |
1308 | break; | |
1309 | } | |
2b87da3b | 1310 | |
aa3378df | 1311 | /* |
089fbbd2 | 1312 | * Got connection. Fork a child to handle it, unless |
1313 | * we are in debugging mode. | |
aa3378df | 1314 | */ |
089fbbd2 | 1315 | if (debug_flag) { |
aa3378df | 1316 | /* |
089fbbd2 | 1317 | * In debugging mode. Close the listening |
1318 | * socket, and start processing the | |
1319 | * connection without forking. | |
aa3378df | 1320 | */ |
089fbbd2 | 1321 | debug("Server will not fork when running in debugging mode."); |
48e671d5 | 1322 | close_listen_socks(); |
5260325f | 1323 | sock_in = newsock; |
1324 | sock_out = newsock; | |
5540ea9b | 1325 | startup_pipe = -1; |
3f7a7e4a | 1326 | pid = getpid(); |
5260325f | 1327 | break; |
089fbbd2 | 1328 | } else { |
1329 | /* | |
1330 | * Normal production daemon. Fork, and have | |
1331 | * the child process the connection. The | |
1332 | * parent continues listening. | |
1333 | */ | |
1334 | if ((pid = fork()) == 0) { | |
1335 | /* | |
1336 | * Child. Close the listening and max_startup | |
1337 | * sockets. Start using the accepted socket. | |
1338 | * Reinitialize logging (since our pid has | |
1339 | * changed). We break out of the loop to handle | |
1340 | * the connection. | |
1341 | */ | |
1342 | startup_pipe = startup_p[1]; | |
7ace8c3b | 1343 | close_startup_pipes(); |
089fbbd2 | 1344 | close_listen_socks(); |
1345 | sock_in = newsock; | |
1346 | sock_out = newsock; | |
1fe6a48f | 1347 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
089fbbd2 | 1348 | break; |
1349 | } | |
5260325f | 1350 | } |
5260325f | 1351 | |
089fbbd2 | 1352 | /* Parent. Stay in the loop. */ |
1353 | if (pid < 0) | |
1354 | error("fork: %.100s", strerror(errno)); | |
1355 | else | |
c457707e | 1356 | debug("Forked child %ld.", (long)pid); |
5260325f | 1357 | |
089fbbd2 | 1358 | close(startup_p[1]); |
5260325f | 1359 | |
089fbbd2 | 1360 | /* Mark that the key has been used (it was "given" to the child). */ |
59c97189 | 1361 | if ((options.protocol & SSH_PROTO_1) && |
1362 | key_used == 0) { | |
1363 | /* Schedule server key regeneration alarm. */ | |
1364 | signal(SIGALRM, key_regeneration_alarm); | |
1365 | alarm(options.key_regeneration_time); | |
1366 | key_used = 1; | |
1367 | } | |
5260325f | 1368 | |
089fbbd2 | 1369 | arc4random_stir(); |
1370 | ||
1371 | /* Close the new socket (the child is now taking care of it). */ | |
1372 | close(newsock); | |
1373 | } | |
48e671d5 | 1374 | /* child process check (or debug mode) */ |
1375 | if (num_listen_socks < 0) | |
1376 | break; | |
5260325f | 1377 | } |
1378 | } | |
8efc0c15 | 1379 | |
5260325f | 1380 | /* This is the child processing a new connection. */ |
1381 | ||
4ac8556b | 1382 | /* |
1383 | * Create a new session and process group since the 4.4BSD | |
1384 | * setlogin() affects the entire process group. We don't | |
1385 | * want the child to be able to affect the parent. | |
1386 | */ | |
30321a9b | 1387 | #if 0 |
1388 | /* XXX: this breaks Solaris */ | |
c28876e9 | 1389 | if (!debug_flag && !inetd_flag && setsid() < 0) |
4ac8556b | 1390 | error("setsid: %.100s", strerror(errno)); |
30321a9b | 1391 | #endif |
4ac8556b | 1392 | |
aa3378df | 1393 | /* |
1394 | * Disable the key regeneration alarm. We will not regenerate the | |
1395 | * key since we are no longer in a position to give it to anyone. We | |
1396 | * will not restart on SIGHUP since it no longer makes sense. | |
1397 | */ | |
5260325f | 1398 | alarm(0); |
1399 | signal(SIGALRM, SIG_DFL); | |
1400 | signal(SIGHUP, SIG_DFL); | |
1401 | signal(SIGTERM, SIG_DFL); | |
1402 | signal(SIGQUIT, SIG_DFL); | |
1403 | signal(SIGCHLD, SIG_DFL); | |
9aaf9be4 | 1404 | signal(SIGINT, SIG_DFL); |
5260325f | 1405 | |
aa3378df | 1406 | /* |
1407 | * Set socket options for the connection. We want the socket to | |
1408 | * close as fast as possible without waiting for anything. If the | |
1409 | * connection is not a socket, these will do nothing. | |
1410 | */ | |
1411 | /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */ | |
5260325f | 1412 | linger.l_onoff = 1; |
1413 | linger.l_linger = 5; | |
db518d9b | 1414 | setsockopt(sock_in, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger)); |
5260325f | 1415 | |
b5c334cc | 1416 | /* Set keepalives if requested. */ |
1417 | if (options.keepalives && | |
db518d9b | 1418 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, |
b5c334cc | 1419 | sizeof(on)) < 0) |
1420 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1421 | ||
aa3378df | 1422 | /* |
1423 | * Register our connection. This turns encryption off because we do | |
1424 | * not have a key. | |
1425 | */ | |
5260325f | 1426 | packet_set_connection(sock_in, sock_out); |
1427 | ||
1428 | remote_port = get_remote_port(); | |
1429 | remote_ip = get_remote_ipaddr(); | |
1430 | ||
5260325f | 1431 | #ifdef LIBWRAP |
ac28afd8 | 1432 | /* Check whether logins are denied from this host. */ |
5260325f | 1433 | { |
1434 | struct request_info req; | |
8efc0c15 | 1435 | |
8fbc356d | 1436 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); |
5260325f | 1437 | fromhost(&req); |
8efc0c15 | 1438 | |
5260325f | 1439 | if (!hosts_access(&req)) { |
ac28afd8 | 1440 | debug("Connection refused by tcp wrapper"); |
563834bb | 1441 | refuse(&req); |
ac28afd8 | 1442 | /* NOTREACHED */ |
1443 | fatal("libwrap refuse returns"); | |
5260325f | 1444 | } |
8efc0c15 | 1445 | } |
48e671d5 | 1446 | #endif /* LIBWRAP */ |
ac28afd8 | 1447 | |
5260325f | 1448 | /* Log the connection. */ |
1449 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
8efc0c15 | 1450 | |
aa3378df | 1451 | /* |
1452 | * We don\'t want to listen forever unless the other side | |
1453 | * successfully authenticates itself. So we set up an alarm which is | |
1454 | * cleared after successful authentication. A limit of zero | |
1455 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1456 | * mode; it is just annoying to have the server exit just when you | |
1457 | * are about to discover the bug. | |
1458 | */ | |
5260325f | 1459 | signal(SIGALRM, grace_alarm_handler); |
1460 | if (!debug_flag) | |
1461 | alarm(options.login_grace_time); | |
1462 | ||
7368a6c8 | 1463 | sshd_exchange_identification(sock_in, sock_out); |
aa3378df | 1464 | /* |
6ffc9c88 | 1465 | * Check that the connection comes from a privileged port. |
c242fc96 | 1466 | * Rhosts-Authentication only makes sense from privileged |
aa3378df | 1467 | * programs. Of course, if the intruder has root access on his local |
1468 | * machine, he can connect from any port. So do not use these | |
1469 | * authentication methods from machines that you do not trust. | |
1470 | */ | |
44b1a8e5 | 1471 | if (options.rhosts_authentication && |
1472 | (remote_port >= IPPORT_RESERVED || | |
1473 | remote_port < IPPORT_RESERVED / 2)) { | |
6ffc9c88 | 1474 | debug("Rhosts Authentication disabled, " |
9ae3f727 | 1475 | "originating port %d not trusted.", remote_port); |
5260325f | 1476 | options.rhosts_authentication = 0; |
5260325f | 1477 | } |
ced49be2 | 1478 | #if defined(KRB4) && !defined(KRB5) |
48e671d5 | 1479 | if (!packet_connection_is_ipv4() && |
1480 | options.kerberos_authentication) { | |
1481 | debug("Kerberos Authentication disabled, only available for IPv4."); | |
1482 | options.kerberos_authentication = 0; | |
1483 | } | |
ced49be2 | 1484 | #endif /* KRB4 && !KRB5 */ |
abf1f107 | 1485 | #ifdef AFS |
1486 | /* If machine has AFS, set process authentication group. */ | |
1487 | if (k_hasafs()) { | |
1488 | k_setpag(); | |
1489 | k_unlog(); | |
1490 | } | |
1491 | #endif /* AFS */ | |
48e671d5 | 1492 | |
5260325f | 1493 | packet_set_nonblocking(); |
1494 | ||
324bf712 | 1495 | if (use_privsep) |
1496 | if ((authctxt = privsep_preauth()) != NULL) | |
1497 | goto authenticated; | |
1853d1ef | 1498 | |
7b2ea3a1 | 1499 | /* perform the key exchange */ |
7b2ea3a1 | 1500 | /* authenticate user and start session */ |
e78a59f5 | 1501 | if (compat20) { |
1502 | do_ssh2_kex(); | |
1b34c1b3 | 1503 | authctxt = do_authentication2(); |
e78a59f5 | 1504 | } else { |
1505 | do_ssh1_kex(); | |
1b34c1b3 | 1506 | authctxt = do_authentication(); |
e78a59f5 | 1507 | } |
324bf712 | 1508 | /* |
1509 | * If we use privilege separation, the unprivileged child transfers | |
1510 | * the current keystate and exits | |
1511 | */ | |
1512 | if (use_privsep) { | |
b5a28cbc | 1513 | mm_send_keystate(pmonitor); |
1853d1ef | 1514 | exit(0); |
324bf712 | 1515 | } |
1853d1ef | 1516 | |
1517 | authenticated: | |
762715ce | 1518 | /* |
1853d1ef | 1519 | * In privilege separation, we fork another child and prepare |
1520 | * file descriptor passing. | |
1521 | */ | |
1522 | if (use_privsep) { | |
324bf712 | 1523 | privsep_postauth(authctxt); |
1524 | /* the monitor process [priv] will not return */ | |
1853d1ef | 1525 | if (!compat20) |
1526 | destroy_sensitive_data(); | |
1527 | } | |
1b34c1b3 | 1528 | |
1529 | /* Perform session preparation. */ | |
1530 | do_authenticated(authctxt); | |
1531 | ||
63284fbb | 1532 | /* The connection has been terminated. */ |
1533 | verbose("Closing connection to %.100s", remote_ip); | |
8efc0c15 | 1534 | |
d94aa2ae | 1535 | #ifdef USE_PAM |
a5c9cd31 | 1536 | finish_pam(); |
d94aa2ae | 1537 | #endif /* USE_PAM */ |
8efc0c15 | 1538 | |
5260325f | 1539 | packet_close(); |
1853d1ef | 1540 | |
1541 | if (use_privsep) | |
1542 | mm_terminate(); | |
1543 | ||
5260325f | 1544 | exit(0); |
1545 | } | |
8efc0c15 | 1546 | |
4f08e98d | 1547 | /* |
1548 | * Decrypt session_key_int using our private server key and private host key | |
1549 | * (key with larger modulus first). | |
1550 | */ | |
1853d1ef | 1551 | int |
4f08e98d | 1552 | ssh1_session_key(BIGNUM *session_key_int) |
1553 | { | |
1554 | int rsafail = 0; | |
1555 | ||
1556 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { | |
1557 | /* Server key has bigger modulus. */ | |
1558 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < | |
1559 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1560 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1561 | get_remote_ipaddr(), | |
1562 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1563 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1564 | SSH_KEY_BITS_RESERVED); | |
1565 | } | |
1566 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1567 | sensitive_data.server_key->rsa) <= 0) | |
1568 | rsafail++; | |
1569 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1570 | sensitive_data.ssh1_host_key->rsa) <= 0) | |
1571 | rsafail++; | |
1572 | } else { | |
1573 | /* Host key has bigger modulus (or they are equal). */ | |
1574 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < | |
1575 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1576 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1577 | get_remote_ipaddr(), | |
1578 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1579 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1580 | SSH_KEY_BITS_RESERVED); | |
1581 | } | |
1582 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1583 | sensitive_data.ssh1_host_key->rsa) < 0) | |
1584 | rsafail++; | |
1585 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1586 | sensitive_data.server_key->rsa) < 0) | |
1587 | rsafail++; | |
1588 | } | |
1589 | return (rsafail); | |
1590 | } | |
5260325f | 1591 | /* |
7b2ea3a1 | 1592 | * SSH1 key exchange |
5260325f | 1593 | */ |
396c147e | 1594 | static void |
1e3b8b07 | 1595 | do_ssh1_kex(void) |
8efc0c15 | 1596 | { |
5260325f | 1597 | int i, len; |
46aa2d1f | 1598 | int rsafail = 0; |
5260325f | 1599 | BIGNUM *session_key_int; |
1e3b8b07 | 1600 | u_char session_key[SSH_SESSION_KEY_LENGTH]; |
1601 | u_char cookie[8]; | |
1602 | u_int cipher_type, auth_mask, protocol_flags; | |
5260325f | 1603 | u_int32_t rand = 0; |
1604 | ||
aa3378df | 1605 | /* |
1606 | * Generate check bytes that the client must send back in the user | |
1607 | * packet in order for it to be accepted; this is used to defy ip | |
1608 | * spoofing attacks. Note that this only works against somebody | |
1609 | * doing IP spoofing from a remote machine; any machine on the local | |
1610 | * network can still see outgoing packets and catch the random | |
1611 | * cookie. This only affects rhosts authentication, and this is one | |
1612 | * of the reasons why it is inherently insecure. | |
1613 | */ | |
5260325f | 1614 | for (i = 0; i < 8; i++) { |
1615 | if (i % 4 == 0) | |
1616 | rand = arc4random(); | |
7b2ea3a1 | 1617 | cookie[i] = rand & 0xff; |
5260325f | 1618 | rand >>= 8; |
1619 | } | |
1620 | ||
aa3378df | 1621 | /* |
1622 | * Send our public key. We include in the packet 64 bits of random | |
1623 | * data that must be matched in the reply in order to prevent IP | |
1624 | * spoofing. | |
1625 | */ | |
5260325f | 1626 | packet_start(SSH_SMSG_PUBLIC_KEY); |
1627 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1628 | packet_put_char(cookie[i]); |
5260325f | 1629 | |
1630 | /* Store our public server RSA key. */ | |
fa08c86b | 1631 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); |
1632 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1633 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
5260325f | 1634 | |
1635 | /* Store our public host RSA key. */ | |
fa08c86b | 1636 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); |
1637 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1638 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
5260325f | 1639 | |
1640 | /* Put protocol flags. */ | |
1641 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1642 | ||
1643 | /* Declare which ciphers we support. */ | |
94ec8c6b | 1644 | packet_put_int(cipher_mask_ssh1(0)); |
5260325f | 1645 | |
1646 | /* Declare supported authentication types. */ | |
1647 | auth_mask = 0; | |
1648 | if (options.rhosts_authentication) | |
1649 | auth_mask |= 1 << SSH_AUTH_RHOSTS; | |
1650 | if (options.rhosts_rsa_authentication) | |
1651 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1652 | if (options.rsa_authentication) | |
1653 | auth_mask |= 1 << SSH_AUTH_RSA; | |
ced49be2 | 1654 | #if defined(KRB4) || defined(KRB5) |
5260325f | 1655 | if (options.kerberos_authentication) |
1656 | auth_mask |= 1 << SSH_AUTH_KERBEROS; | |
8efc0c15 | 1657 | #endif |
ced49be2 | 1658 | #if defined(AFS) || defined(KRB5) |
5260325f | 1659 | if (options.kerberos_tgt_passing) |
1660 | auth_mask |= 1 << SSH_PASS_KERBEROS_TGT; | |
ced49be2 | 1661 | #endif |
1662 | #ifdef AFS | |
5260325f | 1663 | if (options.afs_token_passing) |
1664 | auth_mask |= 1 << SSH_PASS_AFS_TOKEN; | |
8efc0c15 | 1665 | #endif |
5ba55ada | 1666 | if (options.challenge_response_authentication == 1) |
5260325f | 1667 | auth_mask |= 1 << SSH_AUTH_TIS; |
5260325f | 1668 | if (options.password_authentication) |
1669 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1670 | packet_put_int(auth_mask); | |
1671 | ||
1672 | /* Send the packet and wait for it to be sent. */ | |
1673 | packet_send(); | |
1674 | packet_write_wait(); | |
1675 | ||
fa08c86b | 1676 | debug("Sent %d bit server key and %d bit host key.", |
1677 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1678 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
5260325f | 1679 | |
1680 | /* Read clients reply (cipher type and session key). */ | |
54a5250f | 1681 | packet_read_expect(SSH_CMSG_SESSION_KEY); |
5260325f | 1682 | |
2d86a6cc | 1683 | /* Get cipher type and check whether we accept this. */ |
5260325f | 1684 | cipher_type = packet_get_char(); |
1685 | ||
94ec8c6b | 1686 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) |
2d86a6cc | 1687 | packet_disconnect("Warning: client selects unsupported cipher."); |
1688 | ||
5260325f | 1689 | /* Get check bytes from the packet. These must match those we |
1690 | sent earlier with the public key packet. */ | |
1691 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1692 | if (cookie[i] != packet_get_char()) |
5260325f | 1693 | packet_disconnect("IP Spoofing check bytes do not match."); |
1694 | ||
1695 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1696 | ||
1697 | /* Get the encrypted integer. */ | |
b775c6f2 | 1698 | if ((session_key_int = BN_new()) == NULL) |
1699 | fatal("do_ssh1_kex: BN_new failed"); | |
20b279e6 | 1700 | packet_get_bignum(session_key_int); |
5260325f | 1701 | |
5260325f | 1702 | protocol_flags = packet_get_int(); |
1703 | packet_set_protocol_flags(protocol_flags); | |
95500969 | 1704 | packet_check_eom(); |
5260325f | 1705 | |
4f08e98d | 1706 | /* Decrypt session_key_int using host/server keys */ |
1853d1ef | 1707 | rsafail = PRIVSEP(ssh1_session_key(session_key_int)); |
1708 | ||
aa3378df | 1709 | /* |
1710 | * Extract session key from the decrypted integer. The key is in the | |
1711 | * least significant 256 bits of the integer; the first byte of the | |
1712 | * key is in the highest bits. | |
1713 | */ | |
46aa2d1f | 1714 | if (!rsafail) { |
1715 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
1716 | len = BN_num_bytes(session_key_int); | |
1717 | if (len < 0 || len > sizeof(session_key)) { | |
1718 | error("do_connection: bad session key len from %s: " | |
5ca51e19 | 1719 | "session_key_int %d > sizeof(session_key) %lu", |
1720 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); | |
46aa2d1f | 1721 | rsafail++; |
1722 | } else { | |
1723 | memset(session_key, 0, sizeof(session_key)); | |
1724 | BN_bn2bin(session_key_int, | |
1725 | session_key + sizeof(session_key) - len); | |
00be5382 | 1726 | |
1727 | compute_session_id(session_id, cookie, | |
1728 | sensitive_data.ssh1_host_key->rsa->n, | |
1729 | sensitive_data.server_key->rsa->n); | |
1730 | /* | |
1731 | * Xor the first 16 bytes of the session key with the | |
1732 | * session id. | |
1733 | */ | |
1734 | for (i = 0; i < 16; i++) | |
1735 | session_key[i] ^= session_id[i]; | |
46aa2d1f | 1736 | } |
1737 | } | |
1738 | if (rsafail) { | |
00be5382 | 1739 | int bytes = BN_num_bytes(session_key_int); |
f6b1ba8f | 1740 | u_char *buf = xmalloc(bytes); |
00be5382 | 1741 | MD5_CTX md; |
1742 | ||
46aa2d1f | 1743 | log("do_connection: generating a fake encryption key"); |
00be5382 | 1744 | BN_bn2bin(session_key_int, buf); |
1745 | MD5_Init(&md); | |
1746 | MD5_Update(&md, buf, bytes); | |
1747 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1748 | MD5_Final(session_key, &md); | |
1749 | MD5_Init(&md); | |
1750 | MD5_Update(&md, session_key, 16); | |
1751 | MD5_Update(&md, buf, bytes); | |
1752 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1753 | MD5_Final(session_key + 16, &md); | |
1754 | memset(buf, 0, bytes); | |
1755 | xfree(buf); | |
0572fe75 | 1756 | for (i = 0; i < 16; i++) |
1757 | session_id[i] = session_key[i] ^ session_key[i + 16]; | |
46aa2d1f | 1758 | } |
1853d1ef | 1759 | /* Destroy the private and public keys. No longer. */ |
63284fbb | 1760 | destroy_sensitive_data(); |
00be5382 | 1761 | |
1853d1ef | 1762 | if (use_privsep) |
1763 | mm_ssh1_session_id(session_id); | |
1764 | ||
7b2ea3a1 | 1765 | /* Destroy the decrypted integer. It is no longer needed. */ |
1766 | BN_clear_free(session_key_int); | |
1767 | ||
5260325f | 1768 | /* Set the session key. From this on all communications will be encrypted. */ |
1769 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1770 | ||
1771 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1772 | memset(session_key, 0, sizeof(session_key)); | |
1773 | ||
1774 | debug("Received session key; encryption turned on."); | |
1775 | ||
c242fc96 | 1776 | /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ |
5260325f | 1777 | packet_start(SSH_SMSG_SUCCESS); |
1778 | packet_send(); | |
1779 | packet_write_wait(); | |
5260325f | 1780 | } |
e78a59f5 | 1781 | |
1782 | /* | |
1783 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1784 | */ | |
396c147e | 1785 | static void |
1e3b8b07 | 1786 | do_ssh2_kex(void) |
e78a59f5 | 1787 | { |
e78a59f5 | 1788 | Kex *kex; |
e78a59f5 | 1789 | |
a8be9f80 | 1790 | if (options.ciphers != NULL) { |
6ae2364d | 1791 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
a8be9f80 | 1792 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
1793 | } | |
1ad64a93 | 1794 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
1795 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); | |
1796 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
1797 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); | |
1798 | ||
b2552997 | 1799 | if (options.macs != NULL) { |
1800 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
1801 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
1802 | } | |
636f76ca | 1803 | if (!options.compression) { |
1804 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
1805 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
1806 | } | |
fa08c86b | 1807 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
1808 | ||
7a37c112 | 1809 | /* start key exchange */ |
d8ee838b | 1810 | kex = kex_setup(myproposal); |
a5c9ffdb | 1811 | kex->server = 1; |
1812 | kex->client_version_string=client_version_string; | |
1813 | kex->server_version_string=server_version_string; | |
1814 | kex->load_host_key=&get_hostkey_by_type; | |
1853d1ef | 1815 | kex->host_key_index=&get_hostkey_index; |
94ec8c6b | 1816 | |
7a37c112 | 1817 | xxx_kex = kex; |
1818 | ||
c422989b | 1819 | dispatch_run(DISPATCH_BLOCK, &kex->done, kex); |
94ec8c6b | 1820 | |
d1ac6175 | 1821 | session_id2 = kex->session_id; |
1822 | session_id2_len = kex->session_id_len; | |
1823 | ||
94ec8c6b | 1824 | #ifdef DEBUG_KEXDH |
1825 | /* send 1st encrypted/maced/compressed message */ | |
1826 | packet_start(SSH2_MSG_IGNORE); | |
1827 | packet_put_cstring("markus"); | |
1828 | packet_send(); | |
1829 | packet_write_wait(); | |
1830 | #endif | |
a5c9ffdb | 1831 | debug("KEX done"); |
e78a59f5 | 1832 | } |