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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" | |
a666e3b1 | 45 | RCSID("$OpenBSD: sshd.c,v 1.286 2004/02/23 12:02:33 markus Exp $"); |
8efc0c15 | 46 | |
42f11eb2 | 47 | #include <openssl/dh.h> |
48 | #include <openssl/bn.h> | |
436c347c | 49 | #include <openssl/md5.h> |
1853d1ef | 50 | #include <openssl/rand.h> |
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 | |
a6cd1e13 | 104 | extern char **environ; |
260d427b | 105 | |
8efc0c15 | 106 | /* Server configuration options. */ |
107 | ServerOptions options; | |
108 | ||
109 | /* Name of the server configuration file. */ | |
42f11eb2 | 110 | char *config_file_name = _PATH_SERVER_CONFIG_FILE; |
8efc0c15 | 111 | |
6ae2364d | 112 | /* |
48e671d5 | 113 | * Flag indicating whether IPv4 or IPv6. This can be set on the command line. |
114 | * Default value is AF_UNSPEC means both IPv4 and IPv6. | |
115 | */ | |
116 | int IPv4or6 = AF_UNSPEC; | |
117 | ||
5260325f | 118 | /* |
119 | * Debug mode flag. This can be set on the command line. If debug | |
120 | * mode is enabled, extra debugging output will be sent to the system | |
121 | * log, the daemon will not go to background, and will exit after processing | |
122 | * the first connection. | |
123 | */ | |
8efc0c15 | 124 | int debug_flag = 0; |
125 | ||
f87f09aa | 126 | /* Flag indicating that the daemon should only test the configuration and keys. */ |
127 | int test_flag = 0; | |
128 | ||
8efc0c15 | 129 | /* Flag indicating that the daemon is being started from inetd. */ |
130 | int inetd_flag = 0; | |
131 | ||
0b6fbf03 | 132 | /* Flag indicating that sshd should not detach and become a daemon. */ |
133 | int no_daemon_flag = 0; | |
134 | ||
6a17f9c2 | 135 | /* debug goes to stderr unless inetd_flag is set */ |
136 | int log_stderr = 0; | |
137 | ||
8efc0c15 | 138 | /* Saved arguments to main(). */ |
139 | char **saved_argv; | |
4d33e531 | 140 | int saved_argc; |
8efc0c15 | 141 | |
aa3378df | 142 | /* |
48e671d5 | 143 | * The sockets that the server is listening; this is used in the SIGHUP |
144 | * signal handler. | |
aa3378df | 145 | */ |
48e671d5 | 146 | #define MAX_LISTEN_SOCKS 16 |
147 | int listen_socks[MAX_LISTEN_SOCKS]; | |
148 | int num_listen_socks = 0; | |
8efc0c15 | 149 | |
aa3378df | 150 | /* |
151 | * the client's version string, passed by sshd2 in compat mode. if != NULL, | |
152 | * sshd will skip the version-number exchange | |
153 | */ | |
5260325f | 154 | char *client_version_string = NULL; |
7368a6c8 | 155 | char *server_version_string = NULL; |
8efc0c15 | 156 | |
7a37c112 | 157 | /* for rekeying XXX fixme */ |
158 | Kex *xxx_kex; | |
159 | ||
aa3378df | 160 | /* |
161 | * Any really sensitive data in the application is contained in this | |
162 | * structure. The idea is that this structure could be locked into memory so | |
163 | * that the pages do not get written into swap. However, there are some | |
164 | * problems. The private key contains BIGNUMs, and we do not (in principle) | |
165 | * have access to the internals of them, and locking just the structure is | |
166 | * not very useful. Currently, memory locking is not implemented. | |
167 | */ | |
5260325f | 168 | struct { |
cb7bd922 | 169 | Key *server_key; /* ephemeral server key */ |
fa08c86b | 170 | Key *ssh1_host_key; /* ssh1 host key */ |
171 | Key **host_keys; /* all private host keys */ | |
172 | int have_ssh1_key; | |
173 | int have_ssh2_key; | |
00be5382 | 174 | u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH]; |
8efc0c15 | 175 | } sensitive_data; |
176 | ||
aa3378df | 177 | /* |
59c97189 | 178 | * Flag indicating whether the RSA server key needs to be regenerated. |
179 | * Is set in the SIGALRM handler and cleared when the key is regenerated. | |
aa3378df | 180 | */ |
7a934d1b | 181 | static volatile sig_atomic_t key_do_regen = 0; |
8efc0c15 | 182 | |
c9130033 | 183 | /* This is set to true when a signal is received. */ |
7a934d1b | 184 | static volatile sig_atomic_t received_sighup = 0; |
185 | static volatile sig_atomic_t received_sigterm = 0; | |
8efc0c15 | 186 | |
7368a6c8 | 187 | /* session identifier, used by RSA-auth */ |
1e3b8b07 | 188 | u_char session_id[16]; |
e7c0f9d5 | 189 | |
a306f2dd | 190 | /* same for ssh2 */ |
1e3b8b07 | 191 | u_char *session_id2 = NULL; |
a27002e5 | 192 | u_int session_id2_len = 0; |
a306f2dd | 193 | |
c345cf9d | 194 | /* record remote hostname or ip */ |
1e3b8b07 | 195 | u_int utmp_len = MAXHOSTNAMELEN; |
c345cf9d | 196 | |
7ace8c3b | 197 | /* options.max_startup sized array of fd ints */ |
198 | int *startup_pipes = NULL; | |
199 | int startup_pipe; /* in child */ | |
200 | ||
1853d1ef | 201 | /* variables used for privilege separation */ |
98a58eda | 202 | int use_privsep; |
a9b33b95 | 203 | struct monitor *pmonitor = NULL; |
1853d1ef | 204 | |
bc7dfc06 | 205 | /* message to be displayed after login */ |
206 | Buffer loginmsg; | |
207 | ||
2362db19 | 208 | /* global authentication context */ |
209 | Authctxt *the_authctxt = NULL; | |
210 | ||
7368a6c8 | 211 | /* Prototypes for various functions defined later in this file. */ |
396c147e | 212 | void destroy_sensitive_data(void); |
1853d1ef | 213 | void demote_sensitive_data(void); |
c8d54615 | 214 | |
396c147e | 215 | static void do_ssh1_kex(void); |
216 | static void do_ssh2_kex(void); | |
94ec8c6b | 217 | |
48e671d5 | 218 | /* |
219 | * Close all listening sockets | |
220 | */ | |
396c147e | 221 | static void |
48e671d5 | 222 | close_listen_socks(void) |
223 | { | |
224 | int i; | |
e424e241 | 225 | |
48e671d5 | 226 | for (i = 0; i < num_listen_socks; i++) |
227 | close(listen_socks[i]); | |
228 | num_listen_socks = -1; | |
229 | } | |
230 | ||
7ace8c3b | 231 | static void |
232 | close_startup_pipes(void) | |
233 | { | |
234 | int i; | |
e424e241 | 235 | |
7ace8c3b | 236 | if (startup_pipes) |
237 | for (i = 0; i < options.max_startups; i++) | |
238 | if (startup_pipes[i] != -1) | |
239 | close(startup_pipes[i]); | |
240 | } | |
241 | ||
5260325f | 242 | /* |
243 | * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP; | |
244 | * the effect is to reread the configuration file (and to regenerate | |
245 | * the server key). | |
246 | */ | |
396c147e | 247 | static void |
5260325f | 248 | sighup_handler(int sig) |
8efc0c15 | 249 | { |
6056eb35 | 250 | int save_errno = errno; |
251 | ||
5260325f | 252 | received_sighup = 1; |
253 | signal(SIGHUP, sighup_handler); | |
6056eb35 | 254 | errno = save_errno; |
8efc0c15 | 255 | } |
256 | ||
5260325f | 257 | /* |
258 | * Called from the main program after receiving SIGHUP. | |
259 | * Restarts the server. | |
260 | */ | |
396c147e | 261 | static void |
5ca51e19 | 262 | sighup_restart(void) |
8efc0c15 | 263 | { |
bbe88b6d | 264 | logit("Received SIGHUP; restarting."); |
48e671d5 | 265 | close_listen_socks(); |
7ace8c3b | 266 | close_startup_pipes(); |
5260325f | 267 | execv(saved_argv[0], saved_argv); |
bbe88b6d | 268 | logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], |
e424e241 | 269 | strerror(errno)); |
5260325f | 270 | exit(1); |
8efc0c15 | 271 | } |
272 | ||
5260325f | 273 | /* |
274 | * Generic signal handler for terminating signals in the master daemon. | |
5260325f | 275 | */ |
396c147e | 276 | static void |
5260325f | 277 | sigterm_handler(int sig) |
8efc0c15 | 278 | { |
c9130033 | 279 | received_sigterm = sig; |
8efc0c15 | 280 | } |
281 | ||
5260325f | 282 | /* |
283 | * SIGCHLD handler. This is called whenever a child dies. This will then | |
c9130033 | 284 | * reap any zombies left by exited children. |
5260325f | 285 | */ |
396c147e | 286 | static void |
5260325f | 287 | main_sigchld_handler(int sig) |
8efc0c15 | 288 | { |
5260325f | 289 | int save_errno = errno; |
e424e241 | 290 | pid_t pid; |
5260325f | 291 | int status; |
5ad13cd7 | 292 | |
8c38e88b | 293 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || |
294 | (pid < 0 && errno == EINTR)) | |
5260325f | 295 | ; |
5ad13cd7 | 296 | |
5260325f | 297 | signal(SIGCHLD, main_sigchld_handler); |
298 | errno = save_errno; | |
8efc0c15 | 299 | } |
300 | ||
5260325f | 301 | /* |
302 | * Signal handler for the alarm after the login grace period has expired. | |
303 | */ | |
396c147e | 304 | static void |
5260325f | 305 | grace_alarm_handler(int sig) |
8efc0c15 | 306 | { |
c9130033 | 307 | /* XXX no idea how fix this signal handler */ |
308 | ||
a9b33b95 | 309 | if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0) |
310 | kill(pmonitor->m_pid, SIGALRM); | |
311 | ||
5260325f | 312 | /* Log error and exit. */ |
26b9a3d2 | 313 | fatal("Timeout before authentication for %s", get_remote_ipaddr()); |
5260325f | 314 | } |
8efc0c15 | 315 | |
5260325f | 316 | /* |
317 | * Signal handler for the key regeneration alarm. Note that this | |
318 | * alarm only occurs in the daemon waiting for connections, and it does not | |
319 | * do anything with the private key or random state before forking. | |
320 | * Thus there should be no concurrency control/asynchronous execution | |
321 | * problems. | |
322 | */ | |
396c147e | 323 | static void |
cb7bd922 | 324 | generate_ephemeral_server_key(void) |
fa08c86b | 325 | { |
7fdc56c5 | 326 | u_int32_t rnd = 0; |
00be5382 | 327 | int i; |
328 | ||
cd332296 | 329 | verbose("Generating %s%d bit RSA key.", |
76ca7b01 | 330 | sensitive_data.server_key ? "new " : "", options.server_key_bits); |
fa08c86b | 331 | if (sensitive_data.server_key != NULL) |
332 | key_free(sensitive_data.server_key); | |
cd332296 | 333 | sensitive_data.server_key = key_generate(KEY_RSA1, |
76ca7b01 | 334 | options.server_key_bits); |
335 | verbose("RSA key generation complete."); | |
00be5382 | 336 | |
337 | for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) { | |
338 | if (i % 4 == 0) | |
7fdc56c5 | 339 | rnd = arc4random(); |
340 | sensitive_data.ssh1_cookie[i] = rnd & 0xff; | |
341 | rnd >>= 8; | |
00be5382 | 342 | } |
343 | arc4random_stir(); | |
fa08c86b | 344 | } |
f546c780 | 345 | |
396c147e | 346 | static void |
5260325f | 347 | key_regeneration_alarm(int sig) |
348 | { | |
349 | int save_errno = errno; | |
e424e241 | 350 | |
59c97189 | 351 | signal(SIGALRM, SIG_DFL); |
5260325f | 352 | errno = save_errno; |
59c97189 | 353 | key_do_regen = 1; |
5260325f | 354 | } |
8efc0c15 | 355 | |
396c147e | 356 | static void |
7368a6c8 | 357 | sshd_exchange_identification(int sock_in, int sock_out) |
358 | { | |
a8be9f80 | 359 | int i, mismatch; |
7368a6c8 | 360 | int remote_major, remote_minor; |
a8be9f80 | 361 | int major, minor; |
7368a6c8 | 362 | char *s; |
363 | char buf[256]; /* Must not be larger than remote_version. */ | |
364 | char remote_version[256]; /* Must be at least as big as buf. */ | |
365 | ||
a8be9f80 | 366 | if ((options.protocol & SSH_PROTO_1) && |
367 | (options.protocol & SSH_PROTO_2)) { | |
368 | major = PROTOCOL_MAJOR_1; | |
369 | minor = 99; | |
370 | } else if (options.protocol & SSH_PROTO_2) { | |
371 | major = PROTOCOL_MAJOR_2; | |
372 | minor = PROTOCOL_MINOR_2; | |
373 | } else { | |
374 | major = PROTOCOL_MAJOR_1; | |
375 | minor = PROTOCOL_MINOR_1; | |
376 | } | |
377 | snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION); | |
7368a6c8 | 378 | server_version_string = xstrdup(buf); |
379 | ||
7b390973 | 380 | /* Send our protocol version identification. */ |
381 | if (atomicio(vwrite, sock_out, server_version_string, | |
382 | strlen(server_version_string)) | |
383 | != strlen(server_version_string)) { | |
384 | logit("Could not write ident string to %s", get_remote_ipaddr()); | |
2362db19 | 385 | cleanup_exit(255); |
7b390973 | 386 | } |
387 | ||
388 | /* Read other sides version identification. */ | |
389 | memset(buf, 0, sizeof(buf)); | |
390 | for (i = 0; i < sizeof(buf) - 1; i++) { | |
391 | if (atomicio(read, sock_in, &buf[i], 1) != 1) { | |
392 | logit("Did not receive identification string from %s", | |
393 | get_remote_ipaddr()); | |
2362db19 | 394 | cleanup_exit(255); |
7368a6c8 | 395 | } |
7b390973 | 396 | if (buf[i] == '\r') { |
397 | buf[i] = 0; | |
398 | /* Kludge for F-Secure Macintosh < 1.0.2 */ | |
399 | if (i == 12 && | |
400 | strncmp(buf, "SSH-1.5-W1.0", 12) == 0) | |
7368a6c8 | 401 | break; |
7b390973 | 402 | continue; |
403 | } | |
404 | if (buf[i] == '\n') { | |
405 | buf[i] = 0; | |
406 | break; | |
7368a6c8 | 407 | } |
7368a6c8 | 408 | } |
7b390973 | 409 | buf[sizeof(buf) - 1] = 0; |
410 | client_version_string = xstrdup(buf); | |
7368a6c8 | 411 | |
412 | /* | |
413 | * Check that the versions match. In future this might accept | |
414 | * several versions and set appropriate flags to handle them. | |
415 | */ | |
416 | if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n", | |
417 | &remote_major, &remote_minor, remote_version) != 3) { | |
6ae2364d | 418 | s = "Protocol mismatch.\n"; |
dc54438a | 419 | (void) atomicio(vwrite, sock_out, s, strlen(s)); |
7368a6c8 | 420 | close(sock_in); |
421 | close(sock_out); | |
bbe88b6d | 422 | logit("Bad protocol version identification '%.100s' from %s", |
7368a6c8 | 423 | client_version_string, get_remote_ipaddr()); |
2362db19 | 424 | cleanup_exit(255); |
7368a6c8 | 425 | } |
426 | debug("Client protocol version %d.%d; client software version %.100s", | |
184eed6a | 427 | remote_major, remote_minor, remote_version); |
7368a6c8 | 428 | |
e78a59f5 | 429 | compat_datafellows(remote_version); |
430 | ||
9a87e2ac | 431 | if (datafellows & SSH_BUG_PROBE) { |
bbe88b6d | 432 | logit("probed from %s with %s. Don't panic.", |
9a87e2ac | 433 | get_remote_ipaddr(), client_version_string); |
2362db19 | 434 | cleanup_exit(255); |
9a87e2ac | 435 | } |
436 | ||
3a1c54d4 | 437 | if (datafellows & SSH_BUG_SCANNER) { |
bbe88b6d | 438 | logit("scanned from %s with %s. Don't panic.", |
3a1c54d4 | 439 | get_remote_ipaddr(), client_version_string); |
2362db19 | 440 | cleanup_exit(255); |
3a1c54d4 | 441 | } |
442 | ||
a8be9f80 | 443 | mismatch = 0; |
6aacefa7 | 444 | switch (remote_major) { |
7368a6c8 | 445 | case 1: |
a306f2dd | 446 | if (remote_minor == 99) { |
447 | if (options.protocol & SSH_PROTO_2) | |
448 | enable_compat20(); | |
449 | else | |
450 | mismatch = 1; | |
451 | break; | |
452 | } | |
a8be9f80 | 453 | if (!(options.protocol & SSH_PROTO_1)) { |
454 | mismatch = 1; | |
455 | break; | |
456 | } | |
7368a6c8 | 457 | if (remote_minor < 3) { |
089fbbd2 | 458 | packet_disconnect("Your ssh version is too old and " |
7368a6c8 | 459 | "is no longer supported. Please install a newer version."); |
460 | } else if (remote_minor == 3) { | |
461 | /* note that this disables agent-forwarding */ | |
462 | enable_compat13(); | |
463 | } | |
a8be9f80 | 464 | break; |
e78a59f5 | 465 | case 2: |
a8be9f80 | 466 | if (options.protocol & SSH_PROTO_2) { |
e78a59f5 | 467 | enable_compat20(); |
468 | break; | |
469 | } | |
470 | /* FALLTHROUGH */ | |
6ae2364d | 471 | default: |
a8be9f80 | 472 | mismatch = 1; |
473 | break; | |
474 | } | |
475 | chop(server_version_string); | |
a8be9f80 | 476 | debug("Local version string %.200s", server_version_string); |
477 | ||
478 | if (mismatch) { | |
7368a6c8 | 479 | s = "Protocol major versions differ.\n"; |
dc54438a | 480 | (void) atomicio(vwrite, sock_out, s, strlen(s)); |
7368a6c8 | 481 | close(sock_in); |
482 | close(sock_out); | |
bbe88b6d | 483 | logit("Protocol major versions differ for %s: %.200s vs. %.200s", |
a8be9f80 | 484 | get_remote_ipaddr(), |
485 | server_version_string, client_version_string); | |
2362db19 | 486 | cleanup_exit(255); |
7368a6c8 | 487 | } |
a306f2dd | 488 | } |
489 | ||
fa08c86b | 490 | /* Destroy the host and server keys. They will no longer be needed. */ |
a306f2dd | 491 | void |
492 | destroy_sensitive_data(void) | |
493 | { | |
fa08c86b | 494 | int i; |
495 | ||
496 | if (sensitive_data.server_key) { | |
497 | key_free(sensitive_data.server_key); | |
498 | sensitive_data.server_key = NULL; | |
499 | } | |
184eed6a | 500 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 501 | if (sensitive_data.host_keys[i]) { |
502 | key_free(sensitive_data.host_keys[i]); | |
503 | sensitive_data.host_keys[i] = NULL; | |
504 | } | |
505 | } | |
506 | sensitive_data.ssh1_host_key = NULL; | |
00be5382 | 507 | memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH); |
fa08c86b | 508 | } |
fa08c86b | 509 | |
1853d1ef | 510 | /* Demote private to public keys for network child */ |
511 | void | |
512 | demote_sensitive_data(void) | |
513 | { | |
514 | Key *tmp; | |
515 | int i; | |
516 | ||
517 | if (sensitive_data.server_key) { | |
518 | tmp = key_demote(sensitive_data.server_key); | |
519 | key_free(sensitive_data.server_key); | |
520 | sensitive_data.server_key = tmp; | |
521 | } | |
522 | ||
523 | for (i = 0; i < options.num_host_key_files; i++) { | |
524 | if (sensitive_data.host_keys[i]) { | |
525 | tmp = key_demote(sensitive_data.host_keys[i]); | |
526 | key_free(sensitive_data.host_keys[i]); | |
527 | sensitive_data.host_keys[i] = tmp; | |
528 | if (tmp->type == KEY_RSA1) | |
529 | sensitive_data.ssh1_host_key = tmp; | |
530 | } | |
531 | } | |
532 | ||
533 | /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */ | |
534 | } | |
535 | ||
51aeb639 | 536 | static void |
1853d1ef | 537 | privsep_preauth_child(void) |
538 | { | |
7fdc56c5 | 539 | u_int32_t rnd[256]; |
6ded293b | 540 | gid_t gidset[1]; |
2ea6de2b | 541 | struct passwd *pw; |
e424e241 | 542 | int i; |
1853d1ef | 543 | |
544 | /* Enable challenge-response authentication for privilege separation */ | |
545 | privsep_challenge_enable(); | |
546 | ||
547 | for (i = 0; i < 256; i++) | |
7fdc56c5 | 548 | rnd[i] = arc4random(); |
549 | RAND_seed(rnd, sizeof(rnd)); | |
1853d1ef | 550 | |
551 | /* Demote the private keys to public keys. */ | |
552 | demote_sensitive_data(); | |
553 | ||
2ea6de2b | 554 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) |
cdc4fc39 | 555 | fatal("Privilege separation user %s does not exist", |
556 | SSH_PRIVSEP_USER); | |
2ea6de2b | 557 | memset(pw->pw_passwd, 0, strlen(pw->pw_passwd)); |
558 | endpwent(); | |
559 | ||
343288b8 | 560 | /* Change our root directory */ |
1c352e97 | 561 | if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1) |
562 | fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR, | |
563 | strerror(errno)); | |
1853d1ef | 564 | if (chdir("/") == -1) |
edfb66cb | 565 | fatal("chdir(\"/\"): %s", strerror(errno)); |
762715ce | 566 | |
1853d1ef | 567 | /* Drop our privileges */ |
2ea6de2b | 568 | debug3("privsep user:group %u:%u", (u_int)pw->pw_uid, |
569 | (u_int)pw->pw_gid); | |
87809a1f | 570 | #if 0 |
571 | /* XXX not ready, to heavy after chroot */ | |
2ea6de2b | 572 | do_setusercontext(pw); |
87809a1f | 573 | #else |
574 | gidset[0] = pw->pw_gid; | |
87809a1f | 575 | if (setgroups(1, gidset) < 0) |
576 | fatal("setgroups: %.100s", strerror(errno)); | |
577 | permanently_set_uid(pw); | |
578 | #endif | |
1853d1ef | 579 | } |
580 | ||
2362db19 | 581 | static int |
582 | privsep_preauth(Authctxt *authctxt) | |
1853d1ef | 583 | { |
1853d1ef | 584 | int status; |
324bf712 | 585 | pid_t pid; |
1853d1ef | 586 | |
324bf712 | 587 | /* Set up unprivileged child process to deal with network data */ |
b5a28cbc | 588 | pmonitor = monitor_init(); |
324bf712 | 589 | /* Store a pointer to the kex for later rekeying */ |
b5a28cbc | 590 | pmonitor->m_pkex = &xxx_kex; |
324bf712 | 591 | |
592 | pid = fork(); | |
593 | if (pid == -1) { | |
594 | fatal("fork of unprivileged child failed"); | |
595 | } else if (pid != 0) { | |
c457707e | 596 | debug2("Network child is on pid %ld", (long)pid); |
324bf712 | 597 | |
b5a28cbc | 598 | close(pmonitor->m_recvfd); |
a9b33b95 | 599 | pmonitor->m_pid = pid; |
2362db19 | 600 | monitor_child_preauth(authctxt, pmonitor); |
b5a28cbc | 601 | close(pmonitor->m_sendfd); |
324bf712 | 602 | |
603 | /* Sync memory */ | |
b5a28cbc | 604 | monitor_sync(pmonitor); |
324bf712 | 605 | |
606 | /* Wait for the child's exit status */ | |
8c38e88b | 607 | while (waitpid(pid, &status, 0) < 0) |
608 | if (errno != EINTR) | |
609 | break; | |
2362db19 | 610 | return (1); |
324bf712 | 611 | } else { |
612 | /* child */ | |
613 | ||
b5a28cbc | 614 | close(pmonitor->m_sendfd); |
324bf712 | 615 | |
616 | /* Demote the child */ | |
617 | if (getuid() == 0 || geteuid() == 0) | |
618 | privsep_preauth_child(); | |
47c36e5b | 619 | setproctitle("%s", "[net]"); |
324bf712 | 620 | } |
2362db19 | 621 | return (0); |
324bf712 | 622 | } |
623 | ||
624 | static void | |
625 | privsep_postauth(Authctxt *authctxt) | |
626 | { | |
94d8258b | 627 | #ifdef DISABLE_FD_PASSING |
d170feb1 | 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; |
b6c7b7b7 | 676 | const char *p; |
677 | char *ret; | |
fa08c86b | 678 | int i; |
3469eac4 | 679 | |
680 | buffer_init(&b); | |
184eed6a | 681 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 682 | Key *key = sensitive_data.host_keys[i]; |
683 | if (key == NULL) | |
684 | continue; | |
6aacefa7 | 685 | switch (key->type) { |
fa08c86b | 686 | case KEY_RSA: |
687 | case KEY_DSA: | |
3469eac4 | 688 | if (buffer_len(&b) > 0) |
689 | buffer_append(&b, ",", 1); | |
690 | p = key_ssh_name(key); | |
691 | buffer_append(&b, p, strlen(p)); | |
fa08c86b | 692 | break; |
693 | } | |
694 | } | |
3469eac4 | 695 | buffer_append(&b, "\0", 1); |
b6c7b7b7 | 696 | ret = xstrdup(buffer_ptr(&b)); |
3469eac4 | 697 | buffer_free(&b); |
b6c7b7b7 | 698 | debug("list_hostkey_types: %s", ret); |
699 | return ret; | |
fa08c86b | 700 | } |
701 | ||
1853d1ef | 702 | Key * |
fa08c86b | 703 | get_hostkey_by_type(int type) |
704 | { | |
705 | int i; | |
e424e241 | 706 | |
184eed6a | 707 | for (i = 0; i < options.num_host_key_files; i++) { |
fa08c86b | 708 | Key *key = sensitive_data.host_keys[i]; |
709 | if (key != NULL && key->type == type) | |
710 | return key; | |
711 | } | |
712 | return NULL; | |
7368a6c8 | 713 | } |
714 | ||
1853d1ef | 715 | Key * |
716 | get_hostkey_by_index(int ind) | |
717 | { | |
718 | if (ind < 0 || ind >= options.num_host_key_files) | |
719 | return (NULL); | |
720 | return (sensitive_data.host_keys[ind]); | |
721 | } | |
722 | ||
723 | int | |
724 | get_hostkey_index(Key *key) | |
725 | { | |
726 | int i; | |
e424e241 | 727 | |
1853d1ef | 728 | for (i = 0; i < options.num_host_key_files; i++) { |
729 | if (key == sensitive_data.host_keys[i]) | |
730 | return (i); | |
731 | } | |
732 | return (-1); | |
733 | } | |
734 | ||
c345cf9d | 735 | /* |
736 | * returns 1 if connection should be dropped, 0 otherwise. | |
737 | * dropping starts at connection #max_startups_begin with a probability | |
738 | * of (max_startups_rate/100). the probability increases linearly until | |
739 | * all connections are dropped for startups > max_startups | |
740 | */ | |
396c147e | 741 | static int |
c345cf9d | 742 | drop_connection(int startups) |
743 | { | |
744 | double p, r; | |
745 | ||
746 | if (startups < options.max_startups_begin) | |
747 | return 0; | |
748 | if (startups >= options.max_startups) | |
749 | return 1; | |
750 | if (options.max_startups_rate == 100) | |
751 | return 1; | |
752 | ||
753 | p = 100 - options.max_startups_rate; | |
754 | p *= startups - options.max_startups_begin; | |
755 | p /= (double) (options.max_startups - options.max_startups_begin); | |
756 | p += options.max_startups_rate; | |
757 | p /= 100.0; | |
758 | r = arc4random() / (double) UINT_MAX; | |
759 | ||
760 | debug("drop_connection: p %g, r %g", p, r); | |
761 | return (r < p) ? 1 : 0; | |
762 | } | |
763 | ||
2717fa0f | 764 | static void |
765 | usage(void) | |
766 | { | |
418ae4b4 | 767 | fprintf(stderr, "sshd version %s, %s\n", |
768 | SSH_VERSION, SSLeay_version(SSLEAY_VERSION)); | |
2717fa0f | 769 | fprintf(stderr, "Usage: %s [options]\n", __progname); |
770 | fprintf(stderr, "Options:\n"); | |
771 | fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE); | |
772 | fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n"); | |
773 | fprintf(stderr, " -i Started from inetd\n"); | |
774 | fprintf(stderr, " -D Do not fork into daemon mode\n"); | |
775 | fprintf(stderr, " -t Only test configuration file and keys\n"); | |
776 | fprintf(stderr, " -q Quiet (no logging)\n"); | |
777 | fprintf(stderr, " -p port Listen on the specified port (default: 22)\n"); | |
778 | fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n"); | |
779 | fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n"); | |
780 | fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n"); | |
781 | fprintf(stderr, " -h file File from which to read host key (default: %s)\n", | |
782 | _PATH_HOST_KEY_FILE); | |
783 | fprintf(stderr, " -u len Maximum hostname length for utmp recording\n"); | |
784 | fprintf(stderr, " -4 Use IPv4 only\n"); | |
785 | fprintf(stderr, " -6 Use IPv6 only\n"); | |
786 | fprintf(stderr, " -o option Process the option as if it was read from a configuration file.\n"); | |
787 | exit(1); | |
788 | } | |
789 | ||
5260325f | 790 | /* |
791 | * Main program for the daemon. | |
792 | */ | |
8efc0c15 | 793 | int |
794 | main(int ac, char **av) | |
795 | { | |
5260325f | 796 | extern char *optarg; |
797 | extern int optind; | |
089fbbd2 | 798 | int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1; |
9da5c3c9 | 799 | pid_t pid; |
48e671d5 | 800 | socklen_t fromlen; |
48e671d5 | 801 | fd_set *fdset; |
802 | struct sockaddr_storage from; | |
5260325f | 803 | const char *remote_ip; |
804 | int remote_port; | |
5260325f | 805 | FILE *f; |
48e671d5 | 806 | struct addrinfo *ai; |
807 | char ntop[NI_MAXHOST], strport[NI_MAXSERV]; | |
c5894280 | 808 | char *line; |
48e671d5 | 809 | int listen_sock, maxfd; |
089fbbd2 | 810 | int startup_p[2]; |
811 | int startups = 0; | |
aeaa3d9e | 812 | Key *key; |
2362db19 | 813 | Authctxt *authctxt; |
59c97189 | 814 | int ret, key_used = 0; |
5260325f | 815 | |
6e879cb4 | 816 | #ifdef HAVE_SECUREWARE |
817 | (void)set_auth_parameters(ac, av); | |
818 | #endif | |
fda04d7d | 819 | __progname = ssh_get_progname(av[0]); |
264dce47 | 820 | init_rng(); |
821 | ||
d0104542 | 822 | /* Save argv. Duplicate so setproctitle emulation doesn't clobber it */ |
4d33e531 | 823 | saved_argc = ac; |
f420d2ba | 824 | saved_argv = xmalloc(sizeof(*saved_argv) * (ac + 1)); |
d0104542 | 825 | for (i = 0; i < ac; i++) |
826 | saved_argv[i] = xstrdup(av[i]); | |
f420d2ba | 827 | saved_argv[i] = NULL; |
d0104542 | 828 | |
829 | #ifndef HAVE_SETPROCTITLE | |
830 | /* Prepare for later setproctitle emulation */ | |
831 | compat_init_setproctitle(ac, av); | |
416c732d | 832 | av = saved_argv; |
d0104542 | 833 | #endif |
5260325f | 834 | |
835 | /* Initialize configuration options to their default values. */ | |
836 | initialize_server_options(&options); | |
837 | ||
838 | /* Parse command-line arguments. */ | |
7b390973 | 839 | while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqtQ46")) != -1) { |
5260325f | 840 | switch (opt) { |
48e671d5 | 841 | case '4': |
842 | IPv4or6 = AF_INET; | |
843 | break; | |
844 | case '6': | |
845 | IPv4or6 = AF_INET6; | |
846 | break; | |
5260325f | 847 | case 'f': |
848 | config_file_name = optarg; | |
849 | break; | |
850 | case 'd': | |
e053cd2c | 851 | if (debug_flag == 0) { |
bcbf86ec | 852 | debug_flag = 1; |
853 | options.log_level = SYSLOG_LEVEL_DEBUG1; | |
e053cd2c | 854 | } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) |
bcbf86ec | 855 | options.log_level++; |
5260325f | 856 | break; |
0b6fbf03 | 857 | case 'D': |
858 | no_daemon_flag = 1; | |
859 | break; | |
ff14faf1 | 860 | case 'e': |
861 | log_stderr = 1; | |
862 | break; | |
5260325f | 863 | case 'i': |
864 | inetd_flag = 1; | |
865 | break; | |
866 | case 'Q': | |
9bd5b720 | 867 | /* ignored */ |
5260325f | 868 | break; |
869 | case 'q': | |
870 | options.log_level = SYSLOG_LEVEL_QUIET; | |
871 | break; | |
872 | case 'b': | |
873 | options.server_key_bits = atoi(optarg); | |
874 | break; | |
875 | case 'p': | |
48e671d5 | 876 | options.ports_from_cmdline = 1; |
bcbf86ec | 877 | if (options.num_ports >= MAX_PORTS) { |
878 | fprintf(stderr, "too many ports.\n"); | |
879 | exit(1); | |
880 | } | |
2d2a2c65 | 881 | options.ports[options.num_ports++] = a2port(optarg); |
882 | if (options.ports[options.num_ports-1] == 0) { | |
883 | fprintf(stderr, "Bad port number.\n"); | |
884 | exit(1); | |
885 | } | |
5260325f | 886 | break; |
887 | case 'g': | |
e2b1fb42 | 888 | if ((options.login_grace_time = convtime(optarg)) == -1) { |
889 | fprintf(stderr, "Invalid login grace time.\n"); | |
890 | exit(1); | |
891 | } | |
5260325f | 892 | break; |
893 | case 'k': | |
e2b1fb42 | 894 | if ((options.key_regeneration_time = convtime(optarg)) == -1) { |
895 | fprintf(stderr, "Invalid key regeneration interval.\n"); | |
896 | exit(1); | |
897 | } | |
5260325f | 898 | break; |
899 | case 'h': | |
fa08c86b | 900 | if (options.num_host_key_files >= MAX_HOSTKEYS) { |
901 | fprintf(stderr, "too many host keys.\n"); | |
902 | exit(1); | |
903 | } | |
904 | options.host_key_files[options.num_host_key_files++] = optarg; | |
5260325f | 905 | break; |
f87f09aa | 906 | case 't': |
907 | test_flag = 1; | |
908 | break; | |
c345cf9d | 909 | case 'u': |
910 | utmp_len = atoi(optarg); | |
67f04db1 | 911 | if (utmp_len > MAXHOSTNAMELEN) { |
912 | fprintf(stderr, "Invalid utmp length.\n"); | |
913 | exit(1); | |
914 | } | |
c345cf9d | 915 | break; |
2717fa0f | 916 | case 'o': |
c5894280 | 917 | line = xstrdup(optarg); |
918 | if (process_server_config_line(&options, line, | |
2717fa0f | 919 | "command-line", 0) != 0) |
184eed6a | 920 | exit(1); |
c5894280 | 921 | xfree(line); |
2717fa0f | 922 | break; |
5260325f | 923 | case '?': |
924 | default: | |
2717fa0f | 925 | usage(); |
926 | break; | |
5260325f | 927 | } |
928 | } | |
1a92bd7e | 929 | SSLeay_add_all_algorithms(); |
5e4a7219 | 930 | channel_set_af(IPv4or6); |
5260325f | 931 | |
48e671d5 | 932 | /* |
933 | * Force logging to stderr until we have loaded the private host | |
934 | * key (unless started from inetd) | |
935 | */ | |
1fe6a48f | 936 | log_init(__progname, |
980c9344 | 937 | options.log_level == SYSLOG_LEVEL_NOT_SET ? |
938 | SYSLOG_LEVEL_INFO : options.log_level, | |
939 | options.log_facility == SYSLOG_FACILITY_NOT_SET ? | |
940 | SYSLOG_FACILITY_AUTH : options.log_facility, | |
51efad8c | 941 | log_stderr || !inetd_flag); |
48e671d5 | 942 | |
ef51930f | 943 | #ifdef _UNICOS |
1a23ac2c | 944 | /* Cray can define user privs drop all prives now! |
945 | * Not needed on PRIV_SU systems! | |
946 | */ | |
947 | drop_cray_privs(); | |
948 | #endif | |
949 | ||
e339aa53 | 950 | seed_rng(); |
951 | ||
5260325f | 952 | /* Read server configuration options from the configuration file. */ |
953 | read_server_config(&options, config_file_name); | |
954 | ||
955 | /* Fill in default values for those options not explicitly set. */ | |
956 | fill_default_server_options(&options); | |
957 | ||
5260325f | 958 | /* Check that there are no remaining arguments. */ |
959 | if (optind < ac) { | |
960 | fprintf(stderr, "Extra argument %s.\n", av[optind]); | |
961 | exit(1); | |
8efc0c15 | 962 | } |
5260325f | 963 | |
964 | debug("sshd version %.100s", SSH_VERSION); | |
965 | ||
fa08c86b | 966 | /* load private host keys */ |
343288b8 | 967 | sensitive_data.host_keys = xmalloc(options.num_host_key_files * |
968 | sizeof(Key *)); | |
184eed6a | 969 | for (i = 0; i < options.num_host_key_files; i++) |
1e3b8b07 | 970 | sensitive_data.host_keys[i] = NULL; |
fa08c86b | 971 | sensitive_data.server_key = NULL; |
972 | sensitive_data.ssh1_host_key = NULL; | |
973 | sensitive_data.have_ssh1_key = 0; | |
974 | sensitive_data.have_ssh2_key = 0; | |
a306f2dd | 975 | |
184eed6a | 976 | for (i = 0; i < options.num_host_key_files; i++) { |
aeaa3d9e | 977 | key = key_load_private(options.host_key_files[i], "", NULL); |
978 | sensitive_data.host_keys[i] = key; | |
fa08c86b | 979 | if (key == NULL) { |
58cfa257 | 980 | error("Could not load host key: %s", |
981 | options.host_key_files[i]); | |
aeaa3d9e | 982 | sensitive_data.host_keys[i] = NULL; |
fa08c86b | 983 | continue; |
a306f2dd | 984 | } |
6aacefa7 | 985 | switch (key->type) { |
fa08c86b | 986 | case KEY_RSA1: |
987 | sensitive_data.ssh1_host_key = key; | |
988 | sensitive_data.have_ssh1_key = 1; | |
989 | break; | |
990 | case KEY_RSA: | |
991 | case KEY_DSA: | |
992 | sensitive_data.have_ssh2_key = 1; | |
993 | break; | |
a306f2dd | 994 | } |
aeaa3d9e | 995 | debug("private host key: #%d type %d %s", i, key->type, |
996 | key_type(key)); | |
fa08c86b | 997 | } |
998 | if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) { | |
bbe88b6d | 999 | logit("Disabling protocol version 1. Could not load host key"); |
fa08c86b | 1000 | options.protocol &= ~SSH_PROTO_1; |
1001 | } | |
1002 | if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) { | |
bbe88b6d | 1003 | logit("Disabling protocol version 2. Could not load host key"); |
fa08c86b | 1004 | options.protocol &= ~SSH_PROTO_2; |
a306f2dd | 1005 | } |
6a416424 | 1006 | if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) { |
bbe88b6d | 1007 | logit("sshd: no hostkeys available -- exiting."); |
5260325f | 1008 | exit(1); |
1009 | } | |
5260325f | 1010 | |
a306f2dd | 1011 | /* Check certain values for sanity. */ |
1012 | if (options.protocol & SSH_PROTO_1) { | |
1013 | if (options.server_key_bits < 512 || | |
1014 | options.server_key_bits > 32768) { | |
1015 | fprintf(stderr, "Bad server key size.\n"); | |
1016 | exit(1); | |
1017 | } | |
1018 | /* | |
1019 | * Check that server and host key lengths differ sufficiently. This | |
1020 | * is necessary to make double encryption work with rsaref. Oh, I | |
1021 | * hate software patents. I dont know if this can go? Niels | |
1022 | */ | |
1023 | if (options.server_key_bits > | |
e424e241 | 1024 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - |
1025 | SSH_KEY_BITS_RESERVED && options.server_key_bits < | |
1026 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + | |
1027 | SSH_KEY_BITS_RESERVED) { | |
a306f2dd | 1028 | options.server_key_bits = |
e424e241 | 1029 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + |
1030 | SSH_KEY_BITS_RESERVED; | |
a306f2dd | 1031 | debug("Forcing server key to %d bits to make it differ from host key.", |
1032 | options.server_key_bits); | |
1033 | } | |
1034 | } | |
1035 | ||
3cc54fbb | 1036 | if (use_privsep) { |
1037 | struct passwd *pw; | |
1038 | struct stat st; | |
1039 | ||
1040 | if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL) | |
1041 | fatal("Privilege separation user %s does not exist", | |
1042 | SSH_PRIVSEP_USER); | |
1043 | if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) || | |
1044 | (S_ISDIR(st.st_mode) == 0)) | |
1045 | fatal("Missing privilege separation directory: %s", | |
1046 | _PATH_PRIVSEP_CHROOT_DIR); | |
b9b82dab | 1047 | |
1048 | #ifdef HAVE_CYGWIN | |
1049 | if (check_ntsec(_PATH_PRIVSEP_CHROOT_DIR) && | |
1050 | (st.st_uid != getuid () || | |
1051 | (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)) | |
1052 | #else | |
a56313d7 | 1053 | if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0) |
b9b82dab | 1054 | #endif |
5f021474 | 1055 | fatal("%s must be owned by root and not group or " |
1056 | "world-writable.", _PATH_PRIVSEP_CHROOT_DIR); | |
3cc54fbb | 1057 | } |
1058 | ||
f87f09aa | 1059 | /* Configuration looks good, so exit if in test mode. */ |
1060 | if (test_flag) | |
1061 | exit(0); | |
1062 | ||
018a5ea3 | 1063 | /* |
1064 | * Clear out any supplemental groups we may have inherited. This | |
1065 | * prevents inadvertent creation of files with bad modes (in the | |
aff51935 | 1066 | * portable version at least, it's certainly possible for PAM |
1067 | * to create a file, and we can't control the code in every | |
018a5ea3 | 1068 | * module which might be used). |
1069 | */ | |
1070 | if (setgroups(0, NULL) < 0) | |
1071 | debug("setgroups() failed: %.200s", strerror(errno)); | |
1072 | ||
a306f2dd | 1073 | /* Initialize the log (it is reinitialized below in case we forked). */ |
5260325f | 1074 | if (debug_flag && !inetd_flag) |
1075 | log_stderr = 1; | |
1fe6a48f | 1076 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 1077 | |
a306f2dd | 1078 | /* |
1079 | * If not in debugging mode, and not started from inetd, disconnect | |
1080 | * from the controlling terminal, and fork. The original process | |
1081 | * exits. | |
1082 | */ | |
0b6fbf03 | 1083 | if (!(debug_flag || inetd_flag || no_daemon_flag)) { |
8efc0c15 | 1084 | #ifdef TIOCNOTTY |
5260325f | 1085 | int fd; |
8efc0c15 | 1086 | #endif /* TIOCNOTTY */ |
5260325f | 1087 | if (daemon(0, 0) < 0) |
1088 | fatal("daemon() failed: %.200s", strerror(errno)); | |
1089 | ||
1090 | /* Disconnect from the controlling tty. */ | |
8efc0c15 | 1091 | #ifdef TIOCNOTTY |
5ca51e19 | 1092 | fd = open(_PATH_TTY, O_RDWR | O_NOCTTY); |
5260325f | 1093 | if (fd >= 0) { |
1094 | (void) ioctl(fd, TIOCNOTTY, NULL); | |
1095 | close(fd); | |
1096 | } | |
8efc0c15 | 1097 | #endif /* TIOCNOTTY */ |
8efc0c15 | 1098 | } |
5260325f | 1099 | /* Reinitialize the log (because of the fork above). */ |
1fe6a48f | 1100 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
5260325f | 1101 | |
5260325f | 1102 | /* Initialize the random number generator. */ |
1103 | arc4random_stir(); | |
1104 | ||
1105 | /* Chdir to the root directory so that the current disk can be | |
1106 | unmounted if desired. */ | |
1107 | chdir("/"); | |
184eed6a | 1108 | |
a6cd1e13 | 1109 | #ifndef HAVE_CYGWIN |
1110 | /* Clear environment */ | |
1111 | environ[0] = NULL; | |
1112 | #endif | |
1113 | ||
1d3c30db | 1114 | /* ignore SIGPIPE */ |
1115 | signal(SIGPIPE, SIG_IGN); | |
5260325f | 1116 | |
5260325f | 1117 | /* Start listening for a socket, unless started from inetd. */ |
1118 | if (inetd_flag) { | |
ec1f12d3 | 1119 | int s1; |
5260325f | 1120 | s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */ |
ec1f12d3 | 1121 | dup(s1); |
5260325f | 1122 | sock_in = dup(0); |
1123 | sock_out = dup(1); | |
4c8722d9 | 1124 | startup_pipe = -1; |
a306f2dd | 1125 | /* |
1126 | * We intentionally do not close the descriptors 0, 1, and 2 | |
1127 | * as our code for setting the descriptors won\'t work if | |
1128 | * ttyfd happens to be one of those. | |
1129 | */ | |
5260325f | 1130 | debug("inetd sockets after dupping: %d, %d", sock_in, sock_out); |
fa08c86b | 1131 | if (options.protocol & SSH_PROTO_1) |
cb7bd922 | 1132 | generate_ephemeral_server_key(); |
5260325f | 1133 | } else { |
48e671d5 | 1134 | for (ai = options.listen_addrs; ai; ai = ai->ai_next) { |
1135 | if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6) | |
1136 | continue; | |
1137 | if (num_listen_socks >= MAX_LISTEN_SOCKS) | |
1138 | fatal("Too many listen sockets. " | |
1139 | "Enlarge MAX_LISTEN_SOCKS"); | |
1140 | if (getnameinfo(ai->ai_addr, ai->ai_addrlen, | |
1141 | ntop, sizeof(ntop), strport, sizeof(strport), | |
1142 | NI_NUMERICHOST|NI_NUMERICSERV) != 0) { | |
1143 | error("getnameinfo failed"); | |
1144 | continue; | |
1145 | } | |
1146 | /* Create socket for listening. */ | |
3e131a6d | 1147 | listen_sock = socket(ai->ai_family, ai->ai_socktype, |
1148 | ai->ai_protocol); | |
48e671d5 | 1149 | if (listen_sock < 0) { |
1150 | /* kernel may not support ipv6 */ | |
1151 | verbose("socket: %.100s", strerror(errno)); | |
1152 | continue; | |
1153 | } | |
a666e3b1 | 1154 | if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) { |
1155 | error("listen_sock O_NONBLOCK: %s", strerror(errno)); | |
1156 | close(listen_sock); | |
1157 | continue; | |
1158 | } | |
48e671d5 | 1159 | /* |
facfd613 | 1160 | * Set socket options. |
1161 | * Allow local port reuse in TIME_WAIT. | |
48e671d5 | 1162 | */ |
facfd613 | 1163 | if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, |
1164 | &on, sizeof(on)) == -1) | |
1165 | error("setsockopt SO_REUSEADDR: %s", strerror(errno)); | |
48e671d5 | 1166 | |
1167 | debug("Bind to port %s on %s.", strport, ntop); | |
1168 | ||
1169 | /* Bind the socket to the desired port. */ | |
32ced054 | 1170 | if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) { |
1171 | if (!ai->ai_next) | |
1172 | error("Bind to port %s on %s failed: %.200s.", | |
1173 | strport, ntop, strerror(errno)); | |
48e671d5 | 1174 | close(listen_sock); |
1175 | continue; | |
1176 | } | |
1177 | listen_socks[num_listen_socks] = listen_sock; | |
1178 | num_listen_socks++; | |
1179 | ||
1180 | /* Start listening on the port. */ | |
bbe88b6d | 1181 | logit("Server listening on %s port %s.", ntop, strport); |
fce39749 | 1182 | if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0) |
48e671d5 | 1183 | fatal("listen: %.100s", strerror(errno)); |
1184 | ||
5260325f | 1185 | } |
48e671d5 | 1186 | freeaddrinfo(options.listen_addrs); |
1187 | ||
1188 | if (!num_listen_socks) | |
1189 | fatal("Cannot bind any address."); | |
1190 | ||
3aca00a3 | 1191 | if (options.protocol & SSH_PROTO_1) |
1192 | generate_ephemeral_server_key(); | |
1193 | ||
1194 | /* | |
1195 | * Arrange to restart on SIGHUP. The handler needs | |
1196 | * listen_sock. | |
1197 | */ | |
1198 | signal(SIGHUP, sighup_handler); | |
1199 | ||
1200 | signal(SIGTERM, sigterm_handler); | |
1201 | signal(SIGQUIT, sigterm_handler); | |
1202 | ||
1203 | /* Arrange SIGCHLD to be caught. */ | |
1204 | signal(SIGCHLD, main_sigchld_handler); | |
1205 | ||
1206 | /* Write out the pid file after the sigterm handler is setup */ | |
5260325f | 1207 | if (!debug_flag) { |
aa3378df | 1208 | /* |
97fb6912 | 1209 | * Record our pid in /var/run/sshd.pid to make it |
1210 | * easier to kill the correct sshd. We don't want to | |
1211 | * do this before the bind above because the bind will | |
aa3378df | 1212 | * fail if there already is a daemon, and this will |
1213 | * overwrite any old pid in the file. | |
1214 | */ | |
3c62e7eb | 1215 | f = fopen(options.pid_file, "wb"); |
71b9ced0 | 1216 | if (f == NULL) { |
1217 | error("Couldn't create pid file \"%s\": %s", | |
1218 | options.pid_file, strerror(errno)); | |
1219 | } else { | |
c457707e | 1220 | fprintf(f, "%ld\n", (long) getpid()); |
5260325f | 1221 | fclose(f); |
1222 | } | |
8efc0c15 | 1223 | } |
5260325f | 1224 | |
48e671d5 | 1225 | /* setup fd set for listen */ |
089fbbd2 | 1226 | fdset = NULL; |
48e671d5 | 1227 | maxfd = 0; |
1228 | for (i = 0; i < num_listen_socks; i++) | |
1229 | if (listen_socks[i] > maxfd) | |
1230 | maxfd = listen_socks[i]; | |
089fbbd2 | 1231 | /* pipes connected to unauthenticated childs */ |
1232 | startup_pipes = xmalloc(options.max_startups * sizeof(int)); | |
1233 | for (i = 0; i < options.max_startups; i++) | |
1234 | startup_pipes[i] = -1; | |
48e671d5 | 1235 | |
aa3378df | 1236 | /* |
1237 | * Stay listening for connections until the system crashes or | |
1238 | * the daemon is killed with a signal. | |
1239 | */ | |
5260325f | 1240 | for (;;) { |
1241 | if (received_sighup) | |
1242 | sighup_restart(); | |
089fbbd2 | 1243 | if (fdset != NULL) |
1244 | xfree(fdset); | |
b5c334cc | 1245 | fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask); |
089fbbd2 | 1246 | fdset = (fd_set *)xmalloc(fdsetsz); |
48e671d5 | 1247 | memset(fdset, 0, fdsetsz); |
089fbbd2 | 1248 | |
48e671d5 | 1249 | for (i = 0; i < num_listen_socks; i++) |
1250 | FD_SET(listen_socks[i], fdset); | |
089fbbd2 | 1251 | for (i = 0; i < options.max_startups; i++) |
1252 | if (startup_pipes[i] != -1) | |
1253 | FD_SET(startup_pipes[i], fdset); | |
1254 | ||
1255 | /* Wait in select until there is a connection. */ | |
59c97189 | 1256 | ret = select(maxfd+1, fdset, NULL, NULL, NULL); |
1257 | if (ret < 0 && errno != EINTR) | |
1258 | error("select: %.100s", strerror(errno)); | |
c9130033 | 1259 | if (received_sigterm) { |
bbe88b6d | 1260 | logit("Received signal %d; terminating.", |
010f9726 | 1261 | (int) received_sigterm); |
c9130033 | 1262 | close_listen_socks(); |
1263 | unlink(options.pid_file); | |
1264 | exit(255); | |
1265 | } | |
59c97189 | 1266 | if (key_used && key_do_regen) { |
cb7bd922 | 1267 | generate_ephemeral_server_key(); |
59c97189 | 1268 | key_used = 0; |
1269 | key_do_regen = 0; | |
48e671d5 | 1270 | } |
59c97189 | 1271 | if (ret < 0) |
1272 | continue; | |
1273 | ||
089fbbd2 | 1274 | for (i = 0; i < options.max_startups; i++) |
1275 | if (startup_pipes[i] != -1 && | |
1276 | FD_ISSET(startup_pipes[i], fdset)) { | |
1277 | /* | |
1278 | * the read end of the pipe is ready | |
1279 | * if the child has closed the pipe | |
8abcdba4 | 1280 | * after successful authentication |
089fbbd2 | 1281 | * or if the child has died |
1282 | */ | |
1283 | close(startup_pipes[i]); | |
1284 | startup_pipes[i] = -1; | |
1285 | startups--; | |
1286 | } | |
48e671d5 | 1287 | for (i = 0; i < num_listen_socks; i++) { |
1288 | if (!FD_ISSET(listen_socks[i], fdset)) | |
5260325f | 1289 | continue; |
089fbbd2 | 1290 | fromlen = sizeof(from); |
1291 | newsock = accept(listen_socks[i], (struct sockaddr *)&from, | |
1292 | &fromlen); | |
1293 | if (newsock < 0) { | |
1294 | if (errno != EINTR && errno != EWOULDBLOCK) | |
1295 | error("accept: %.100s", strerror(errno)); | |
1296 | continue; | |
1297 | } | |
a666e3b1 | 1298 | if (fcntl(newsock, F_SETFL, 0) < 0) { |
1299 | error("newsock del O_NONBLOCK: %s", strerror(errno)); | |
1300 | close(newsock); | |
1301 | continue; | |
1302 | } | |
c345cf9d | 1303 | if (drop_connection(startups) == 1) { |
1304 | debug("drop connection #%d", startups); | |
089fbbd2 | 1305 | close(newsock); |
1306 | continue; | |
1307 | } | |
1308 | if (pipe(startup_p) == -1) { | |
1309 | close(newsock); | |
1310 | continue; | |
1311 | } | |
1312 | ||
1313 | for (j = 0; j < options.max_startups; j++) | |
1314 | if (startup_pipes[j] == -1) { | |
1315 | startup_pipes[j] = startup_p[0]; | |
1316 | if (maxfd < startup_p[0]) | |
1317 | maxfd = startup_p[0]; | |
1318 | startups++; | |
1319 | break; | |
1320 | } | |
2b87da3b | 1321 | |
aa3378df | 1322 | /* |
089fbbd2 | 1323 | * Got connection. Fork a child to handle it, unless |
1324 | * we are in debugging mode. | |
aa3378df | 1325 | */ |
089fbbd2 | 1326 | if (debug_flag) { |
aa3378df | 1327 | /* |
089fbbd2 | 1328 | * In debugging mode. Close the listening |
1329 | * socket, and start processing the | |
1330 | * connection without forking. | |
aa3378df | 1331 | */ |
089fbbd2 | 1332 | debug("Server will not fork when running in debugging mode."); |
48e671d5 | 1333 | close_listen_socks(); |
5260325f | 1334 | sock_in = newsock; |
1335 | sock_out = newsock; | |
5540ea9b | 1336 | startup_pipe = -1; |
3f7a7e4a | 1337 | pid = getpid(); |
5260325f | 1338 | break; |
089fbbd2 | 1339 | } else { |
1340 | /* | |
1341 | * Normal production daemon. Fork, and have | |
1342 | * the child process the connection. The | |
1343 | * parent continues listening. | |
1344 | */ | |
1345 | if ((pid = fork()) == 0) { | |
1346 | /* | |
1347 | * Child. Close the listening and max_startup | |
1348 | * sockets. Start using the accepted socket. | |
1349 | * Reinitialize logging (since our pid has | |
1350 | * changed). We break out of the loop to handle | |
1351 | * the connection. | |
1352 | */ | |
1353 | startup_pipe = startup_p[1]; | |
7ace8c3b | 1354 | close_startup_pipes(); |
089fbbd2 | 1355 | close_listen_socks(); |
1356 | sock_in = newsock; | |
1357 | sock_out = newsock; | |
1fe6a48f | 1358 | log_init(__progname, options.log_level, options.log_facility, log_stderr); |
089fbbd2 | 1359 | break; |
1360 | } | |
5260325f | 1361 | } |
5260325f | 1362 | |
089fbbd2 | 1363 | /* Parent. Stay in the loop. */ |
1364 | if (pid < 0) | |
1365 | error("fork: %.100s", strerror(errno)); | |
1366 | else | |
c457707e | 1367 | debug("Forked child %ld.", (long)pid); |
5260325f | 1368 | |
089fbbd2 | 1369 | close(startup_p[1]); |
5260325f | 1370 | |
089fbbd2 | 1371 | /* Mark that the key has been used (it was "given" to the child). */ |
59c97189 | 1372 | if ((options.protocol & SSH_PROTO_1) && |
1373 | key_used == 0) { | |
1374 | /* Schedule server key regeneration alarm. */ | |
f00d1f78 | 1375 | signal(SIGALRM, key_regeneration_alarm); |
59c97189 | 1376 | alarm(options.key_regeneration_time); |
1377 | key_used = 1; | |
1378 | } | |
5260325f | 1379 | |
089fbbd2 | 1380 | arc4random_stir(); |
1381 | ||
1382 | /* Close the new socket (the child is now taking care of it). */ | |
1383 | close(newsock); | |
1384 | } | |
48e671d5 | 1385 | /* child process check (or debug mode) */ |
1386 | if (num_listen_socks < 0) | |
1387 | break; | |
5260325f | 1388 | } |
1389 | } | |
8efc0c15 | 1390 | |
5260325f | 1391 | /* This is the child processing a new connection. */ |
1392 | ||
4ac8556b | 1393 | /* |
1394 | * Create a new session and process group since the 4.4BSD | |
1395 | * setlogin() affects the entire process group. We don't | |
1396 | * want the child to be able to affect the parent. | |
1397 | */ | |
ad84c479 | 1398 | #if !defined(SSHD_ACQUIRES_CTTY) |
6ecd00f8 | 1399 | /* |
ad84c479 | 1400 | * If setsid is called, on some platforms sshd will later acquire a |
1401 | * controlling terminal which will result in "could not set | |
1402 | * controlling tty" errors. | |
6ecd00f8 | 1403 | */ |
c28876e9 | 1404 | if (!debug_flag && !inetd_flag && setsid() < 0) |
4ac8556b | 1405 | error("setsid: %.100s", strerror(errno)); |
30321a9b | 1406 | #endif |
4ac8556b | 1407 | |
aa3378df | 1408 | /* |
1409 | * Disable the key regeneration alarm. We will not regenerate the | |
1410 | * key since we are no longer in a position to give it to anyone. We | |
1411 | * will not restart on SIGHUP since it no longer makes sense. | |
1412 | */ | |
5260325f | 1413 | alarm(0); |
1414 | signal(SIGALRM, SIG_DFL); | |
1415 | signal(SIGHUP, SIG_DFL); | |
1416 | signal(SIGTERM, SIG_DFL); | |
1417 | signal(SIGQUIT, SIG_DFL); | |
1418 | signal(SIGCHLD, SIG_DFL); | |
9aaf9be4 | 1419 | signal(SIGINT, SIG_DFL); |
5260325f | 1420 | |
fd573618 | 1421 | /* Set SO_KEEPALIVE if requested. */ |
1422 | if (options.tcp_keep_alive && | |
db518d9b | 1423 | setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, |
b5c334cc | 1424 | sizeof(on)) < 0) |
1425 | error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno)); | |
1426 | ||
aa3378df | 1427 | /* |
1428 | * Register our connection. This turns encryption off because we do | |
1429 | * not have a key. | |
1430 | */ | |
5260325f | 1431 | packet_set_connection(sock_in, sock_out); |
1432 | ||
1433 | remote_port = get_remote_port(); | |
1434 | remote_ip = get_remote_ipaddr(); | |
1435 | ||
5260325f | 1436 | #ifdef LIBWRAP |
ac28afd8 | 1437 | /* Check whether logins are denied from this host. */ |
5260325f | 1438 | { |
1439 | struct request_info req; | |
8efc0c15 | 1440 | |
8fbc356d | 1441 | request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0); |
5260325f | 1442 | fromhost(&req); |
8efc0c15 | 1443 | |
5260325f | 1444 | if (!hosts_access(&req)) { |
ac28afd8 | 1445 | debug("Connection refused by tcp wrapper"); |
563834bb | 1446 | refuse(&req); |
ac28afd8 | 1447 | /* NOTREACHED */ |
1448 | fatal("libwrap refuse returns"); | |
5260325f | 1449 | } |
8efc0c15 | 1450 | } |
48e671d5 | 1451 | #endif /* LIBWRAP */ |
ac28afd8 | 1452 | |
5260325f | 1453 | /* Log the connection. */ |
1454 | verbose("Connection from %.500s port %d", remote_ip, remote_port); | |
8efc0c15 | 1455 | |
aa3378df | 1456 | /* |
1457 | * We don\'t want to listen forever unless the other side | |
1458 | * successfully authenticates itself. So we set up an alarm which is | |
1459 | * cleared after successful authentication. A limit of zero | |
1460 | * indicates no limit. Note that we don\'t set the alarm in debugging | |
1461 | * mode; it is just annoying to have the server exit just when you | |
1462 | * are about to discover the bug. | |
1463 | */ | |
f00d1f78 | 1464 | signal(SIGALRM, grace_alarm_handler); |
5260325f | 1465 | if (!debug_flag) |
1466 | alarm(options.login_grace_time); | |
1467 | ||
7368a6c8 | 1468 | sshd_exchange_identification(sock_in, sock_out); |
0598d99d | 1469 | |
5260325f | 1470 | packet_set_nonblocking(); |
1471 | ||
aff51935 | 1472 | /* prepare buffers to collect authentication messages */ |
bc7dfc06 | 1473 | buffer_init(&loginmsg); |
1474 | ||
2362db19 | 1475 | /* allocate authentication context */ |
1476 | authctxt = xmalloc(sizeof(*authctxt)); | |
1477 | memset(authctxt, 0, sizeof(*authctxt)); | |
1478 | ||
1479 | /* XXX global for cleanup, access from other modules */ | |
1480 | the_authctxt = authctxt; | |
1481 | ||
324bf712 | 1482 | if (use_privsep) |
2362db19 | 1483 | if (privsep_preauth(authctxt) == 1) |
324bf712 | 1484 | goto authenticated; |
1853d1ef | 1485 | |
7b2ea3a1 | 1486 | /* perform the key exchange */ |
7b2ea3a1 | 1487 | /* authenticate user and start session */ |
e78a59f5 | 1488 | if (compat20) { |
1489 | do_ssh2_kex(); | |
2362db19 | 1490 | do_authentication2(authctxt); |
e78a59f5 | 1491 | } else { |
1492 | do_ssh1_kex(); | |
2362db19 | 1493 | do_authentication(authctxt); |
e78a59f5 | 1494 | } |
324bf712 | 1495 | /* |
1496 | * If we use privilege separation, the unprivileged child transfers | |
1497 | * the current keystate and exits | |
1498 | */ | |
1499 | if (use_privsep) { | |
b5a28cbc | 1500 | mm_send_keystate(pmonitor); |
1853d1ef | 1501 | exit(0); |
324bf712 | 1502 | } |
1853d1ef | 1503 | |
1504 | authenticated: | |
762715ce | 1505 | /* |
1853d1ef | 1506 | * In privilege separation, we fork another child and prepare |
1507 | * file descriptor passing. | |
1508 | */ | |
1509 | if (use_privsep) { | |
324bf712 | 1510 | privsep_postauth(authctxt); |
1511 | /* the monitor process [priv] will not return */ | |
1853d1ef | 1512 | if (!compat20) |
1513 | destroy_sensitive_data(); | |
1514 | } | |
1b34c1b3 | 1515 | |
2362db19 | 1516 | /* Start session. */ |
1b34c1b3 | 1517 | do_authenticated(authctxt); |
1518 | ||
63284fbb | 1519 | /* The connection has been terminated. */ |
1520 | verbose("Closing connection to %.100s", remote_ip); | |
8efc0c15 | 1521 | |
d94aa2ae | 1522 | #ifdef USE_PAM |
7fceb20d | 1523 | if (options.use_pam) |
1524 | finish_pam(); | |
d94aa2ae | 1525 | #endif /* USE_PAM */ |
8efc0c15 | 1526 | |
5260325f | 1527 | packet_close(); |
1853d1ef | 1528 | |
1529 | if (use_privsep) | |
1530 | mm_terminate(); | |
1531 | ||
5260325f | 1532 | exit(0); |
1533 | } | |
8efc0c15 | 1534 | |
4f08e98d | 1535 | /* |
1536 | * Decrypt session_key_int using our private server key and private host key | |
1537 | * (key with larger modulus first). | |
1538 | */ | |
1853d1ef | 1539 | int |
4f08e98d | 1540 | ssh1_session_key(BIGNUM *session_key_int) |
1541 | { | |
1542 | int rsafail = 0; | |
1543 | ||
1544 | if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) { | |
1545 | /* Server key has bigger modulus. */ | |
1546 | if (BN_num_bits(sensitive_data.server_key->rsa->n) < | |
1547 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1548 | fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d", | |
1549 | get_remote_ipaddr(), | |
1550 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1551 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1552 | SSH_KEY_BITS_RESERVED); | |
1553 | } | |
1554 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1555 | sensitive_data.server_key->rsa) <= 0) | |
1556 | rsafail++; | |
1557 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1558 | sensitive_data.ssh1_host_key->rsa) <= 0) | |
1559 | rsafail++; | |
1560 | } else { | |
1561 | /* Host key has bigger modulus (or they are equal). */ | |
1562 | if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) < | |
1563 | BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) { | |
1564 | fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d", | |
1565 | get_remote_ipaddr(), | |
1566 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n), | |
1567 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1568 | SSH_KEY_BITS_RESERVED); | |
1569 | } | |
1570 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1571 | sensitive_data.ssh1_host_key->rsa) < 0) | |
1572 | rsafail++; | |
1573 | if (rsa_private_decrypt(session_key_int, session_key_int, | |
1574 | sensitive_data.server_key->rsa) < 0) | |
1575 | rsafail++; | |
1576 | } | |
1577 | return (rsafail); | |
1578 | } | |
5260325f | 1579 | /* |
7b2ea3a1 | 1580 | * SSH1 key exchange |
5260325f | 1581 | */ |
396c147e | 1582 | static void |
1e3b8b07 | 1583 | do_ssh1_kex(void) |
8efc0c15 | 1584 | { |
5260325f | 1585 | int i, len; |
46aa2d1f | 1586 | int rsafail = 0; |
5260325f | 1587 | BIGNUM *session_key_int; |
1e3b8b07 | 1588 | u_char session_key[SSH_SESSION_KEY_LENGTH]; |
1589 | u_char cookie[8]; | |
1590 | u_int cipher_type, auth_mask, protocol_flags; | |
7fdc56c5 | 1591 | u_int32_t rnd = 0; |
5260325f | 1592 | |
aa3378df | 1593 | /* |
1594 | * Generate check bytes that the client must send back in the user | |
1595 | * packet in order for it to be accepted; this is used to defy ip | |
1596 | * spoofing attacks. Note that this only works against somebody | |
1597 | * doing IP spoofing from a remote machine; any machine on the local | |
1598 | * network can still see outgoing packets and catch the random | |
1599 | * cookie. This only affects rhosts authentication, and this is one | |
1600 | * of the reasons why it is inherently insecure. | |
1601 | */ | |
5260325f | 1602 | for (i = 0; i < 8; i++) { |
1603 | if (i % 4 == 0) | |
7fdc56c5 | 1604 | rnd = arc4random(); |
1605 | cookie[i] = rnd & 0xff; | |
1606 | rnd >>= 8; | |
5260325f | 1607 | } |
1608 | ||
aa3378df | 1609 | /* |
1610 | * Send our public key. We include in the packet 64 bits of random | |
1611 | * data that must be matched in the reply in order to prevent IP | |
1612 | * spoofing. | |
1613 | */ | |
5260325f | 1614 | packet_start(SSH_SMSG_PUBLIC_KEY); |
1615 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1616 | packet_put_char(cookie[i]); |
5260325f | 1617 | |
1618 | /* Store our public server RSA key. */ | |
fa08c86b | 1619 | packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n)); |
1620 | packet_put_bignum(sensitive_data.server_key->rsa->e); | |
1621 | packet_put_bignum(sensitive_data.server_key->rsa->n); | |
5260325f | 1622 | |
1623 | /* Store our public host RSA key. */ | |
fa08c86b | 1624 | packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); |
1625 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e); | |
1626 | packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n); | |
5260325f | 1627 | |
1628 | /* Put protocol flags. */ | |
1629 | packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN); | |
1630 | ||
1631 | /* Declare which ciphers we support. */ | |
94ec8c6b | 1632 | packet_put_int(cipher_mask_ssh1(0)); |
5260325f | 1633 | |
1634 | /* Declare supported authentication types. */ | |
1635 | auth_mask = 0; | |
5260325f | 1636 | if (options.rhosts_rsa_authentication) |
1637 | auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA; | |
1638 | if (options.rsa_authentication) | |
1639 | auth_mask |= 1 << SSH_AUTH_RSA; | |
5ba55ada | 1640 | if (options.challenge_response_authentication == 1) |
5260325f | 1641 | auth_mask |= 1 << SSH_AUTH_TIS; |
5260325f | 1642 | if (options.password_authentication) |
1643 | auth_mask |= 1 << SSH_AUTH_PASSWORD; | |
1644 | packet_put_int(auth_mask); | |
1645 | ||
1646 | /* Send the packet and wait for it to be sent. */ | |
1647 | packet_send(); | |
1648 | packet_write_wait(); | |
1649 | ||
fa08c86b | 1650 | debug("Sent %d bit server key and %d bit host key.", |
1651 | BN_num_bits(sensitive_data.server_key->rsa->n), | |
1652 | BN_num_bits(sensitive_data.ssh1_host_key->rsa->n)); | |
5260325f | 1653 | |
1654 | /* Read clients reply (cipher type and session key). */ | |
54a5250f | 1655 | packet_read_expect(SSH_CMSG_SESSION_KEY); |
5260325f | 1656 | |
2d86a6cc | 1657 | /* Get cipher type and check whether we accept this. */ |
5260325f | 1658 | cipher_type = packet_get_char(); |
1659 | ||
94ec8c6b | 1660 | if (!(cipher_mask_ssh1(0) & (1 << cipher_type))) |
2d86a6cc | 1661 | packet_disconnect("Warning: client selects unsupported cipher."); |
1662 | ||
5260325f | 1663 | /* Get check bytes from the packet. These must match those we |
1664 | sent earlier with the public key packet. */ | |
1665 | for (i = 0; i < 8; i++) | |
7b2ea3a1 | 1666 | if (cookie[i] != packet_get_char()) |
5260325f | 1667 | packet_disconnect("IP Spoofing check bytes do not match."); |
1668 | ||
1669 | debug("Encryption type: %.200s", cipher_name(cipher_type)); | |
1670 | ||
1671 | /* Get the encrypted integer. */ | |
b775c6f2 | 1672 | if ((session_key_int = BN_new()) == NULL) |
1673 | fatal("do_ssh1_kex: BN_new failed"); | |
20b279e6 | 1674 | packet_get_bignum(session_key_int); |
5260325f | 1675 | |
5260325f | 1676 | protocol_flags = packet_get_int(); |
1677 | packet_set_protocol_flags(protocol_flags); | |
95500969 | 1678 | packet_check_eom(); |
5260325f | 1679 | |
4f08e98d | 1680 | /* Decrypt session_key_int using host/server keys */ |
1853d1ef | 1681 | rsafail = PRIVSEP(ssh1_session_key(session_key_int)); |
1682 | ||
aa3378df | 1683 | /* |
1684 | * Extract session key from the decrypted integer. The key is in the | |
1685 | * least significant 256 bits of the integer; the first byte of the | |
1686 | * key is in the highest bits. | |
1687 | */ | |
46aa2d1f | 1688 | if (!rsafail) { |
1689 | BN_mask_bits(session_key_int, sizeof(session_key) * 8); | |
1690 | len = BN_num_bytes(session_key_int); | |
1691 | if (len < 0 || len > sizeof(session_key)) { | |
1692 | error("do_connection: bad session key len from %s: " | |
5ca51e19 | 1693 | "session_key_int %d > sizeof(session_key) %lu", |
1694 | get_remote_ipaddr(), len, (u_long)sizeof(session_key)); | |
46aa2d1f | 1695 | rsafail++; |
1696 | } else { | |
1697 | memset(session_key, 0, sizeof(session_key)); | |
1698 | BN_bn2bin(session_key_int, | |
1699 | session_key + sizeof(session_key) - len); | |
00be5382 | 1700 | |
1701 | compute_session_id(session_id, cookie, | |
1702 | sensitive_data.ssh1_host_key->rsa->n, | |
1703 | sensitive_data.server_key->rsa->n); | |
1704 | /* | |
1705 | * Xor the first 16 bytes of the session key with the | |
1706 | * session id. | |
1707 | */ | |
1708 | for (i = 0; i < 16; i++) | |
1709 | session_key[i] ^= session_id[i]; | |
46aa2d1f | 1710 | } |
1711 | } | |
1712 | if (rsafail) { | |
00be5382 | 1713 | int bytes = BN_num_bytes(session_key_int); |
f6b1ba8f | 1714 | u_char *buf = xmalloc(bytes); |
00be5382 | 1715 | MD5_CTX md; |
1716 | ||
bbe88b6d | 1717 | logit("do_connection: generating a fake encryption key"); |
00be5382 | 1718 | BN_bn2bin(session_key_int, buf); |
1719 | MD5_Init(&md); | |
1720 | MD5_Update(&md, buf, bytes); | |
1721 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1722 | MD5_Final(session_key, &md); | |
1723 | MD5_Init(&md); | |
1724 | MD5_Update(&md, session_key, 16); | |
1725 | MD5_Update(&md, buf, bytes); | |
1726 | MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH); | |
1727 | MD5_Final(session_key + 16, &md); | |
1728 | memset(buf, 0, bytes); | |
1729 | xfree(buf); | |
0572fe75 | 1730 | for (i = 0; i < 16; i++) |
1731 | session_id[i] = session_key[i] ^ session_key[i + 16]; | |
46aa2d1f | 1732 | } |
1853d1ef | 1733 | /* Destroy the private and public keys. No longer. */ |
63284fbb | 1734 | destroy_sensitive_data(); |
00be5382 | 1735 | |
1853d1ef | 1736 | if (use_privsep) |
1737 | mm_ssh1_session_id(session_id); | |
1738 | ||
7b2ea3a1 | 1739 | /* Destroy the decrypted integer. It is no longer needed. */ |
1740 | BN_clear_free(session_key_int); | |
1741 | ||
5260325f | 1742 | /* Set the session key. From this on all communications will be encrypted. */ |
1743 | packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type); | |
1744 | ||
1745 | /* Destroy our copy of the session key. It is no longer needed. */ | |
1746 | memset(session_key, 0, sizeof(session_key)); | |
1747 | ||
1748 | debug("Received session key; encryption turned on."); | |
1749 | ||
c242fc96 | 1750 | /* Send an acknowledgment packet. Note that this packet is sent encrypted. */ |
5260325f | 1751 | packet_start(SSH_SMSG_SUCCESS); |
1752 | packet_send(); | |
1753 | packet_write_wait(); | |
5260325f | 1754 | } |
e78a59f5 | 1755 | |
1756 | /* | |
1757 | * SSH2 key exchange: diffie-hellman-group1-sha1 | |
1758 | */ | |
396c147e | 1759 | static void |
1e3b8b07 | 1760 | do_ssh2_kex(void) |
e78a59f5 | 1761 | { |
e78a59f5 | 1762 | Kex *kex; |
e78a59f5 | 1763 | |
a8be9f80 | 1764 | if (options.ciphers != NULL) { |
6ae2364d | 1765 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
a8be9f80 | 1766 | myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers; |
1767 | } | |
1ad64a93 | 1768 | myproposal[PROPOSAL_ENC_ALGS_CTOS] = |
1769 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]); | |
1770 | myproposal[PROPOSAL_ENC_ALGS_STOC] = | |
1771 | compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]); | |
1772 | ||
b2552997 | 1773 | if (options.macs != NULL) { |
1774 | myproposal[PROPOSAL_MAC_ALGS_CTOS] = | |
1775 | myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs; | |
1776 | } | |
636f76ca | 1777 | if (!options.compression) { |
1778 | myproposal[PROPOSAL_COMP_ALGS_CTOS] = | |
1779 | myproposal[PROPOSAL_COMP_ALGS_STOC] = "none"; | |
1780 | } | |
fa08c86b | 1781 | myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types(); |
1782 | ||
7a37c112 | 1783 | /* start key exchange */ |
d8ee838b | 1784 | kex = kex_setup(myproposal); |
98a58eda | 1785 | kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; |
1786 | kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; | |
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 | } |
2362db19 | 1809 | |
1810 | /* server specific fatal cleanup */ | |
1811 | void | |
1812 | cleanup_exit(int i) | |
1813 | { | |
1814 | if (the_authctxt) | |
1815 | do_cleanup(the_authctxt); | |
1816 | _exit(i); | |
1817 | } |