Annotation of src/usr.bin/ssh/sshd.c, Revision 1.331
1.331 ! markus 1: /* $OpenBSD: sshd.c,v 1.330 2006/03/25 13:17:02 djm Exp $ */
1.86 markus 2: /*
1.65 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
1.126 deraadt 6: * This program is the ssh daemon. It listens for connections from clients,
7: * and performs authentication, executes use commands or shell, and forwards
1.65 deraadt 8: * information to/from the application to the user client over an encrypted
1.126 deraadt 9: * connection. This can also handle forwarding of X11, TCP/IP, and
10: * authentication agent connections.
1.98 markus 11: *
1.126 deraadt 12: * As far as I am concerned, the code I have written for this software
13: * can be used freely for any purpose. Any derived versions of this
14: * software must be clearly marked as such, and if the derived work is
15: * incompatible with the protocol description in the RFC file, it must be
16: * called by a name other than "ssh" or "Secure Shell".
17: *
18: * SSH2 implementation:
1.231 provos 19: * Privilege Separation:
1.126 deraadt 20: *
1.231 provos 21: * Copyright (c) 2000, 2001, 2002 Markus Friedl. All rights reserved.
22: * Copyright (c) 2002 Niels Provos. All rights reserved.
1.126 deraadt 23: *
24: * Redistribution and use in source and binary forms, with or without
25: * modification, are permitted provided that the following conditions
26: * are met:
27: * 1. Redistributions of source code must retain the above copyright
28: * notice, this list of conditions and the following disclaimer.
29: * 2. Redistributions in binary form must reproduce the above copyright
30: * notice, this list of conditions and the following disclaimer in the
31: * documentation and/or other materials provided with the distribution.
32: *
33: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
34: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
36: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
37: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
38: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
39: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
40: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
41: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
42: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.65 deraadt 43: */
1.1 deraadt 44:
45: #include "includes.h"
1.320 stevesk 46:
47: #include <sys/ioctl.h>
1.321 stevesk 48: #include <sys/types.h>
49: #include <sys/wait.h>
1.323 stevesk 50: #include <sys/stat.h>
1.319 stevesk 51:
52: #include <paths.h>
1.322 stevesk 53: #include <signal.h>
1.1 deraadt 54:
1.155 markus 55: #include <openssl/dh.h>
56: #include <openssl/bn.h>
1.226 markus 57: #include <openssl/md5.h>
1.231 provos 58: #include <openssl/rand.h>
1.155 markus 59:
60: #include "ssh.h"
61: #include "ssh1.h"
62: #include "ssh2.h"
1.1 deraadt 63: #include "xmalloc.h"
64: #include "rsa.h"
1.171 djm 65: #include "sshpty.h"
1.1 deraadt 66: #include "packet.h"
1.155 markus 67: #include "log.h"
1.1 deraadt 68: #include "servconf.h"
69: #include "uidswap.h"
1.33 markus 70: #include "compat.h"
1.96 markus 71: #include "buffer.h"
1.294 djm 72: #include "bufaux.h"
1.155 markus 73: #include "cipher.h"
1.98 markus 74: #include "kex.h"
1.96 markus 75: #include "key.h"
1.129 provos 76: #include "dh.h"
1.98 markus 77: #include "myproposal.h"
1.108 markus 78: #include "authfile.h"
1.154 markus 79: #include "pathnames.h"
1.155 markus 80: #include "atomicio.h"
81: #include "canohost.h"
82: #include "auth.h"
83: #include "misc.h"
1.294 djm 84: #include "msg.h"
1.186 markus 85: #include "dispatch.h"
1.206 stevesk 86: #include "channels.h"
1.230 provos 87: #include "session.h"
1.231 provos 88: #include "monitor_mm.h"
89: #include "monitor.h"
90: #include "monitor_wrap.h"
91: #include "monitor_fdpass.h"
1.1 deraadt 92:
93: #ifdef LIBWRAP
94: #include <tcpd.h>
95: #include <syslog.h>
96: int allow_severity = LOG_INFO;
97: int deny_severity = LOG_WARNING;
98: #endif /* LIBWRAP */
99:
100: #ifndef O_NOCTTY
101: #define O_NOCTTY 0
102: #endif
103:
1.296 djm 104: /* Re-exec fds */
105: #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
106: #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
107: #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
108: #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
109:
1.138 markus 110: extern char *__progname;
111:
1.1 deraadt 112: /* Server configuration options. */
113: ServerOptions options;
114:
115: /* Name of the server configuration file. */
1.154 markus 116: char *config_file_name = _PATH_SERVER_CONFIG_FILE;
1.1 deraadt 117:
1.105 markus 118: /*
1.65 deraadt 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: */
1.1 deraadt 124: int debug_flag = 0;
125:
1.203 stevesk 126: /* Flag indicating that the daemon should only test the configuration and keys. */
127: int test_flag = 0;
128:
1.1 deraadt 129: /* Flag indicating that the daemon is being started from inetd. */
130: int inetd_flag = 0;
131:
1.135 markus 132: /* Flag indicating that sshd should not detach and become a daemon. */
133: int no_daemon_flag = 0;
134:
1.47 markus 135: /* debug goes to stderr unless inetd_flag is set */
136: int log_stderr = 0;
137:
1.1 deraadt 138: /* Saved arguments to main(). */
139: char **saved_argv;
140:
1.294 djm 141: /* re-exec */
142: int rexeced_flag = 0;
143: int rexec_flag = 1;
144: int rexec_argc = 0;
145: char **rexec_argv;
146:
1.66 markus 147: /*
1.75 markus 148: * The sockets that the server is listening; this is used in the SIGHUP
149: * signal handler.
1.66 markus 150: */
1.75 markus 151: #define MAX_LISTEN_SOCKS 16
152: int listen_socks[MAX_LISTEN_SOCKS];
153: int num_listen_socks = 0;
1.1 deraadt 154:
1.66 markus 155: /*
156: * the client's version string, passed by sshd2 in compat mode. if != NULL,
157: * sshd will skip the version-number exchange
158: */
1.61 markus 159: char *client_version_string = NULL;
1.96 markus 160: char *server_version_string = NULL;
1.1 deraadt 161:
1.189 markus 162: /* for rekeying XXX fixme */
163: Kex *xxx_kex;
164:
1.66 markus 165: /*
166: * Any really sensitive data in the application is contained in this
167: * structure. The idea is that this structure could be locked into memory so
168: * that the pages do not get written into swap. However, there are some
169: * problems. The private key contains BIGNUMs, and we do not (in principle)
170: * have access to the internals of them, and locking just the structure is
171: * not very useful. Currently, memory locking is not implemented.
172: */
1.64 markus 173: struct {
1.174 deraadt 174: Key *server_key; /* ephemeral server key */
1.134 markus 175: Key *ssh1_host_key; /* ssh1 host key */
176: Key **host_keys; /* all private host keys */
177: int have_ssh1_key;
178: int have_ssh2_key;
1.169 markus 179: u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
1.1 deraadt 180: } sensitive_data;
181:
1.66 markus 182: /*
1.151 markus 183: * Flag indicating whether the RSA server key needs to be regenerated.
184: * Is set in the SIGALRM handler and cleared when the key is regenerated.
1.66 markus 185: */
1.212 markus 186: static volatile sig_atomic_t key_do_regen = 0;
1.1 deraadt 187:
1.199 markus 188: /* This is set to true when a signal is received. */
1.212 markus 189: static volatile sig_atomic_t received_sighup = 0;
190: static volatile sig_atomic_t received_sigterm = 0;
1.1 deraadt 191:
1.96 markus 192: /* session identifier, used by RSA-auth */
1.140 markus 193: u_char session_id[16];
1.96 markus 194:
1.108 markus 195: /* same for ssh2 */
1.140 markus 196: u_char *session_id2 = NULL;
1.269 markus 197: u_int session_id2_len = 0;
1.108 markus 198:
1.125 markus 199: /* record remote hostname or ip */
1.140 markus 200: u_int utmp_len = MAXHOSTNAMELEN;
1.125 markus 201:
1.211 markus 202: /* options.max_startup sized array of fd ints */
203: int *startup_pipes = NULL;
204: int startup_pipe; /* in child */
205:
1.231 provos 206: /* variables used for privilege separation */
1.263 markus 207: int use_privsep;
1.285 dtucker 208: struct monitor *pmonitor = NULL;
1.231 provos 209:
1.278 markus 210: /* global authentication context */
211: Authctxt *the_authctxt = NULL;
212:
1.299 dtucker 213: /* message to be displayed after login */
214: Buffer loginmsg;
215:
1.1 deraadt 216: /* Prototypes for various functions defined later in this file. */
1.200 itojun 217: void destroy_sensitive_data(void);
1.231 provos 218: void demote_sensitive_data(void);
1.87 markus 219:
1.200 itojun 220: static void do_ssh1_kex(void);
221: static void do_ssh2_kex(void);
1.129 provos 222:
1.87 markus 223: /*
1.75 markus 224: * Close all listening sockets
225: */
1.200 itojun 226: static void
1.75 markus 227: close_listen_socks(void)
228: {
229: int i;
1.250 deraadt 230:
1.75 markus 231: for (i = 0; i < num_listen_socks; i++)
232: close(listen_socks[i]);
233: num_listen_socks = -1;
234: }
235:
1.211 markus 236: static void
237: close_startup_pipes(void)
238: {
239: int i;
1.250 deraadt 240:
1.211 markus 241: if (startup_pipes)
242: for (i = 0; i < options.max_startups; i++)
243: if (startup_pipes[i] != -1)
244: close(startup_pipes[i]);
245: }
246:
1.75 markus 247: /*
1.65 deraadt 248: * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
249: * the effect is to reread the configuration file (and to regenerate
250: * the server key).
251: */
1.327 deraadt 252:
253: /*ARGSUSED*/
1.200 itojun 254: static void
1.64 markus 255: sighup_handler(int sig)
1.1 deraadt 256: {
1.210 deraadt 257: int save_errno = errno;
258:
1.64 markus 259: received_sighup = 1;
260: signal(SIGHUP, sighup_handler);
1.210 deraadt 261: errno = save_errno;
1.1 deraadt 262: }
263:
1.65 deraadt 264: /*
265: * Called from the main program after receiving SIGHUP.
266: * Restarts the server.
267: */
1.200 itojun 268: static void
1.165 itojun 269: sighup_restart(void)
1.1 deraadt 270: {
1.264 itojun 271: logit("Received SIGHUP; restarting.");
1.75 markus 272: close_listen_socks();
1.211 markus 273: close_startup_pipes();
1.64 markus 274: execv(saved_argv[0], saved_argv);
1.264 itojun 275: logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
1.250 deraadt 276: strerror(errno));
1.64 markus 277: exit(1);
1.1 deraadt 278: }
279:
1.65 deraadt 280: /*
281: * Generic signal handler for terminating signals in the master daemon.
282: */
1.327 deraadt 283: /*ARGSUSED*/
1.200 itojun 284: static void
1.64 markus 285: sigterm_handler(int sig)
1.1 deraadt 286: {
1.199 markus 287: received_sigterm = sig;
1.1 deraadt 288: }
289:
1.65 deraadt 290: /*
291: * SIGCHLD handler. This is called whenever a child dies. This will then
1.199 markus 292: * reap any zombies left by exited children.
1.65 deraadt 293: */
1.327 deraadt 294: /*ARGSUSED*/
1.200 itojun 295: static void
1.64 markus 296: main_sigchld_handler(int sig)
1.1 deraadt 297: {
1.250 deraadt 298: int save_errno = errno;
1.239 markus 299: pid_t pid;
1.64 markus 300: int status;
1.60 deraadt 301:
1.239 markus 302: while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
303: (pid < 0 && errno == EINTR))
1.64 markus 304: ;
1.60 deraadt 305:
1.64 markus 306: signal(SIGCHLD, main_sigchld_handler);
307: errno = save_errno;
1.1 deraadt 308: }
309:
1.65 deraadt 310: /*
311: * Signal handler for the alarm after the login grace period has expired.
312: */
1.327 deraadt 313: /*ARGSUSED*/
1.200 itojun 314: static void
1.64 markus 315: grace_alarm_handler(int sig)
1.1 deraadt 316: {
1.199 markus 317: /* XXX no idea how fix this signal handler */
318:
1.285 dtucker 319: if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
320: kill(pmonitor->m_pid, SIGALRM);
321:
1.64 markus 322: /* Log error and exit. */
1.259 markus 323: fatal("Timeout before authentication for %s", get_remote_ipaddr());
1.62 markus 324: }
325:
1.65 deraadt 326: /*
327: * Signal handler for the key regeneration alarm. Note that this
328: * alarm only occurs in the daemon waiting for connections, and it does not
329: * do anything with the private key or random state before forking.
330: * Thus there should be no concurrency control/asynchronous execution
331: * problems.
332: */
1.200 itojun 333: static void
1.174 deraadt 334: generate_ephemeral_server_key(void)
1.134 markus 335: {
1.254 deraadt 336: u_int32_t rnd = 0;
1.169 markus 337: int i;
338:
1.191 markus 339: verbose("Generating %s%d bit RSA key.",
1.185 djm 340: sensitive_data.server_key ? "new " : "", options.server_key_bits);
1.134 markus 341: if (sensitive_data.server_key != NULL)
342: key_free(sensitive_data.server_key);
1.191 markus 343: sensitive_data.server_key = key_generate(KEY_RSA1,
1.185 djm 344: options.server_key_bits);
345: verbose("RSA key generation complete.");
1.169 markus 346:
347: for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
348: if (i % 4 == 0)
1.254 deraadt 349: rnd = arc4random();
350: sensitive_data.ssh1_cookie[i] = rnd & 0xff;
351: rnd >>= 8;
1.169 markus 352: }
1.134 markus 353: arc4random_stir();
354: }
1.147 deraadt 355:
1.327 deraadt 356: /*ARGSUSED*/
1.200 itojun 357: static void
1.64 markus 358: key_regeneration_alarm(int sig)
1.1 deraadt 359: {
1.64 markus 360: int save_errno = errno;
1.250 deraadt 361:
1.151 markus 362: signal(SIGALRM, SIG_DFL);
1.64 markus 363: errno = save_errno;
1.151 markus 364: key_do_regen = 1;
1.98 markus 365: }
366:
1.200 itojun 367: static void
1.96 markus 368: sshd_exchange_identification(int sock_in, int sock_out)
369: {
1.311 djm 370: u_int i;
371: int mismatch;
1.96 markus 372: int remote_major, remote_minor;
1.102 markus 373: int major, minor;
1.96 markus 374: char *s;
375: char buf[256]; /* Must not be larger than remote_version. */
376: char remote_version[256]; /* Must be at least as big as buf. */
377:
1.103 markus 378: if ((options.protocol & SSH_PROTO_1) &&
379: (options.protocol & SSH_PROTO_2)) {
1.102 markus 380: major = PROTOCOL_MAJOR_1;
381: minor = 99;
382: } else if (options.protocol & SSH_PROTO_2) {
383: major = PROTOCOL_MAJOR_2;
384: minor = PROTOCOL_MINOR_2;
385: } else {
386: major = PROTOCOL_MAJOR_1;
387: minor = PROTOCOL_MINOR_1;
388: }
389: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
1.96 markus 390: server_version_string = xstrdup(buf);
391:
1.272 markus 392: /* Send our protocol version identification. */
393: if (atomicio(vwrite, sock_out, server_version_string,
394: strlen(server_version_string))
395: != strlen(server_version_string)) {
396: logit("Could not write ident string to %s", get_remote_ipaddr());
1.278 markus 397: cleanup_exit(255);
1.272 markus 398: }
399:
400: /* Read other sides version identification. */
401: memset(buf, 0, sizeof(buf));
402: for (i = 0; i < sizeof(buf) - 1; i++) {
403: if (atomicio(read, sock_in, &buf[i], 1) != 1) {
404: logit("Did not receive identification string from %s",
405: get_remote_ipaddr());
1.278 markus 406: cleanup_exit(255);
1.96 markus 407: }
1.272 markus 408: if (buf[i] == '\r') {
409: buf[i] = 0;
410: /* Kludge for F-Secure Macintosh < 1.0.2 */
411: if (i == 12 &&
412: strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
1.96 markus 413: break;
1.272 markus 414: continue;
415: }
416: if (buf[i] == '\n') {
417: buf[i] = 0;
418: break;
1.96 markus 419: }
420: }
1.272 markus 421: buf[sizeof(buf) - 1] = 0;
422: client_version_string = xstrdup(buf);
1.96 markus 423:
424: /*
425: * Check that the versions match. In future this might accept
426: * several versions and set appropriate flags to handle them.
427: */
428: if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
429: &remote_major, &remote_minor, remote_version) != 3) {
1.105 markus 430: s = "Protocol mismatch.\n";
1.271 deraadt 431: (void) atomicio(vwrite, sock_out, s, strlen(s));
1.96 markus 432: close(sock_in);
433: close(sock_out);
1.264 itojun 434: logit("Bad protocol version identification '%.100s' from %s",
1.96 markus 435: client_version_string, get_remote_ipaddr());
1.278 markus 436: cleanup_exit(255);
1.96 markus 437: }
438: debug("Client protocol version %d.%d; client software version %.100s",
1.217 deraadt 439: remote_major, remote_minor, remote_version);
1.96 markus 440:
1.98 markus 441: compat_datafellows(remote_version);
1.260 mickey 442:
443: if (datafellows & SSH_BUG_PROBE) {
1.264 itojun 444: logit("probed from %s with %s. Don't panic.",
1.260 mickey 445: get_remote_ipaddr(), client_version_string);
1.278 markus 446: cleanup_exit(255);
1.260 mickey 447: }
1.175 deraadt 448:
449: if (datafellows & SSH_BUG_SCANNER) {
1.264 itojun 450: logit("scanned from %s with %s. Don't panic.",
1.175 deraadt 451: get_remote_ipaddr(), client_version_string);
1.278 markus 452: cleanup_exit(255);
1.175 deraadt 453: }
1.98 markus 454:
1.102 markus 455: mismatch = 0;
1.214 deraadt 456: switch (remote_major) {
1.96 markus 457: case 1:
1.108 markus 458: if (remote_minor == 99) {
459: if (options.protocol & SSH_PROTO_2)
460: enable_compat20();
461: else
462: mismatch = 1;
463: break;
464: }
1.102 markus 465: if (!(options.protocol & SSH_PROTO_1)) {
466: mismatch = 1;
467: break;
468: }
1.96 markus 469: if (remote_minor < 3) {
1.121 provos 470: packet_disconnect("Your ssh version is too old and "
1.96 markus 471: "is no longer supported. Please install a newer version.");
472: } else if (remote_minor == 3) {
473: /* note that this disables agent-forwarding */
474: enable_compat13();
475: }
1.102 markus 476: break;
1.98 markus 477: case 2:
1.102 markus 478: if (options.protocol & SSH_PROTO_2) {
1.98 markus 479: enable_compat20();
480: break;
481: }
1.99 markus 482: /* FALLTHROUGH */
1.105 markus 483: default:
1.102 markus 484: mismatch = 1;
485: break;
486: }
487: chop(server_version_string);
488: debug("Local version string %.200s", server_version_string);
489:
490: if (mismatch) {
1.96 markus 491: s = "Protocol major versions differ.\n";
1.271 deraadt 492: (void) atomicio(vwrite, sock_out, s, strlen(s));
1.96 markus 493: close(sock_in);
494: close(sock_out);
1.264 itojun 495: logit("Protocol major versions differ for %s: %.200s vs. %.200s",
1.102 markus 496: get_remote_ipaddr(),
497: server_version_string, client_version_string);
1.278 markus 498: cleanup_exit(255);
1.96 markus 499: }
1.108 markus 500: }
501:
1.134 markus 502: /* Destroy the host and server keys. They will no longer be needed. */
1.108 markus 503: void
504: destroy_sensitive_data(void)
505: {
1.134 markus 506: int i;
507:
508: if (sensitive_data.server_key) {
509: key_free(sensitive_data.server_key);
510: sensitive_data.server_key = NULL;
511: }
1.217 deraadt 512: for (i = 0; i < options.num_host_key_files; i++) {
1.134 markus 513: if (sensitive_data.host_keys[i]) {
514: key_free(sensitive_data.host_keys[i]);
515: sensitive_data.host_keys[i] = NULL;
516: }
517: }
518: sensitive_data.ssh1_host_key = NULL;
1.169 markus 519: memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
1.134 markus 520: }
521:
1.231 provos 522: /* Demote private to public keys for network child */
523: void
524: demote_sensitive_data(void)
525: {
526: Key *tmp;
527: int i;
528:
529: if (sensitive_data.server_key) {
530: tmp = key_demote(sensitive_data.server_key);
531: key_free(sensitive_data.server_key);
532: sensitive_data.server_key = tmp;
533: }
534:
535: for (i = 0; i < options.num_host_key_files; i++) {
536: if (sensitive_data.host_keys[i]) {
537: tmp = key_demote(sensitive_data.host_keys[i]);
538: key_free(sensitive_data.host_keys[i]);
539: sensitive_data.host_keys[i] = tmp;
540: if (tmp->type == KEY_RSA1)
541: sensitive_data.ssh1_host_key = tmp;
542: }
543: }
544:
545: /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
546: }
547:
1.233 markus 548: static void
1.231 provos 549: privsep_preauth_child(void)
550: {
1.254 deraadt 551: u_int32_t rnd[256];
1.253 deraadt 552: gid_t gidset[1];
1.250 deraadt 553: struct passwd *pw;
1.231 provos 554: int i;
555:
556: /* Enable challenge-response authentication for privilege separation */
557: privsep_challenge_enable();
558:
559: for (i = 0; i < 256; i++)
1.254 deraadt 560: rnd[i] = arc4random();
561: RAND_seed(rnd, sizeof(rnd));
1.231 provos 562:
563: /* Demote the private keys to public keys. */
564: demote_sensitive_data();
565:
1.235 stevesk 566: if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1.240 djm 567: fatal("Privilege separation user %s does not exist",
568: SSH_PRIVSEP_USER);
1.235 stevesk 569: memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
570: endpwent();
571:
1.255 deraadt 572: /* Change our root directory */
1.232 stevesk 573: if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
574: fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
575: strerror(errno));
1.231 provos 576: if (chdir("/") == -1)
1.236 stevesk 577: fatal("chdir(\"/\"): %s", strerror(errno));
1.234 markus 578:
1.231 provos 579: /* Drop our privileges */
1.235 stevesk 580: debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
581: (u_int)pw->pw_gid);
1.251 markus 582: #if 0
1.287 djm 583: /* XXX not ready, too heavy after chroot */
1.235 stevesk 584: do_setusercontext(pw);
1.251 markus 585: #else
586: gidset[0] = pw->pw_gid;
587: if (setgroups(1, gidset) < 0)
588: fatal("setgroups: %.100s", strerror(errno));
589: permanently_set_uid(pw);
590: #endif
1.231 provos 591: }
592:
1.278 markus 593: static int
594: privsep_preauth(Authctxt *authctxt)
1.237 markus 595: {
596: int status;
597: pid_t pid;
598:
599: /* Set up unprivileged child process to deal with network data */
1.242 mouring 600: pmonitor = monitor_init();
1.237 markus 601: /* Store a pointer to the kex for later rekeying */
1.242 mouring 602: pmonitor->m_pkex = &xxx_kex;
1.237 markus 603:
604: pid = fork();
605: if (pid == -1) {
606: fatal("fork of unprivileged child failed");
607: } else if (pid != 0) {
1.245 mpech 608: debug2("Network child is on pid %ld", (long)pid);
1.237 markus 609:
1.242 mouring 610: close(pmonitor->m_recvfd);
1.285 dtucker 611: pmonitor->m_pid = pid;
1.278 markus 612: monitor_child_preauth(authctxt, pmonitor);
1.242 mouring 613: close(pmonitor->m_sendfd);
1.237 markus 614:
615: /* Sync memory */
1.242 mouring 616: monitor_sync(pmonitor);
1.237 markus 617:
618: /* Wait for the child's exit status */
1.239 markus 619: while (waitpid(pid, &status, 0) < 0)
620: if (errno != EINTR)
621: break;
1.278 markus 622: return (1);
1.237 markus 623: } else {
624: /* child */
625:
1.242 mouring 626: close(pmonitor->m_sendfd);
1.237 markus 627:
628: /* Demote the child */
629: if (getuid() == 0 || geteuid() == 0)
630: privsep_preauth_child();
1.238 stevesk 631: setproctitle("%s", "[net]");
1.237 markus 632: }
1.278 markus 633: return (0);
1.237 markus 634: }
635:
1.233 markus 636: static void
1.237 markus 637: privsep_postauth(Authctxt *authctxt)
1.231 provos 638: {
639: if (authctxt->pw->pw_uid == 0 || options.use_login) {
640: /* File descriptor passing is broken or root login */
641: use_privsep = 0;
1.315 djm 642: goto skip;
1.231 provos 643: }
1.234 markus 644:
1.231 provos 645: /* New socket pair */
1.242 mouring 646: monitor_reinit(pmonitor);
1.231 provos 647:
1.242 mouring 648: pmonitor->m_pid = fork();
649: if (pmonitor->m_pid == -1)
1.231 provos 650: fatal("fork of unprivileged child failed");
1.242 mouring 651: else if (pmonitor->m_pid != 0) {
1.245 mpech 652: debug2("User child is on pid %ld", (long)pmonitor->m_pid);
1.242 mouring 653: close(pmonitor->m_recvfd);
1.307 otto 654: buffer_clear(&loginmsg);
1.242 mouring 655: monitor_child_postauth(pmonitor);
1.231 provos 656:
657: /* NEVERREACHED */
658: exit(0);
659: }
660:
1.242 mouring 661: close(pmonitor->m_sendfd);
1.231 provos 662:
663: /* Demote the private keys to public keys. */
664: demote_sensitive_data();
665:
666: /* Drop privileges */
667: do_setusercontext(authctxt->pw);
668:
1.315 djm 669: skip:
1.231 provos 670: /* It is safe now to apply the key state */
1.242 mouring 671: monitor_apply_keystate(pmonitor);
1.312 markus 672:
673: /*
674: * Tell the packet layer that authentication was successful, since
675: * this information is not part of the key state.
676: */
677: packet_set_authenticated();
1.231 provos 678: }
679:
1.200 itojun 680: static char *
1.134 markus 681: list_hostkey_types(void)
682: {
1.223 markus 683: Buffer b;
1.281 jakob 684: const char *p;
685: char *ret;
1.134 markus 686: int i;
1.223 markus 687:
688: buffer_init(&b);
1.217 deraadt 689: for (i = 0; i < options.num_host_key_files; i++) {
1.134 markus 690: Key *key = sensitive_data.host_keys[i];
691: if (key == NULL)
692: continue;
1.214 deraadt 693: switch (key->type) {
1.134 markus 694: case KEY_RSA:
695: case KEY_DSA:
1.223 markus 696: if (buffer_len(&b) > 0)
697: buffer_append(&b, ",", 1);
698: p = key_ssh_name(key);
699: buffer_append(&b, p, strlen(p));
1.134 markus 700: break;
701: }
702: }
1.223 markus 703: buffer_append(&b, "\0", 1);
1.281 jakob 704: ret = xstrdup(buffer_ptr(&b));
1.223 markus 705: buffer_free(&b);
1.281 jakob 706: debug("list_hostkey_types: %s", ret);
707: return ret;
1.134 markus 708: }
709:
1.231 provos 710: Key *
1.134 markus 711: get_hostkey_by_type(int type)
712: {
713: int i;
1.250 deraadt 714:
1.217 deraadt 715: for (i = 0; i < options.num_host_key_files; i++) {
1.134 markus 716: Key *key = sensitive_data.host_keys[i];
717: if (key != NULL && key->type == type)
718: return key;
719: }
720: return NULL;
1.96 markus 721: }
722:
1.231 provos 723: Key *
724: get_hostkey_by_index(int ind)
725: {
726: if (ind < 0 || ind >= options.num_host_key_files)
727: return (NULL);
728: return (sensitive_data.host_keys[ind]);
729: }
730:
731: int
732: get_hostkey_index(Key *key)
733: {
734: int i;
1.250 deraadt 735:
1.231 provos 736: for (i = 0; i < options.num_host_key_files; i++) {
737: if (key == sensitive_data.host_keys[i])
738: return (i);
739: }
740: return (-1);
741: }
742:
1.124 markus 743: /*
744: * returns 1 if connection should be dropped, 0 otherwise.
745: * dropping starts at connection #max_startups_begin with a probability
746: * of (max_startups_rate/100). the probability increases linearly until
747: * all connections are dropped for startups > max_startups
748: */
1.200 itojun 749: static int
1.124 markus 750: drop_connection(int startups)
751: {
1.303 mickey 752: int p, r;
1.124 markus 753:
754: if (startups < options.max_startups_begin)
755: return 0;
756: if (startups >= options.max_startups)
757: return 1;
758: if (options.max_startups_rate == 100)
759: return 1;
760:
761: p = 100 - options.max_startups_rate;
762: p *= startups - options.max_startups_begin;
1.303 mickey 763: p /= options.max_startups - options.max_startups_begin;
1.124 markus 764: p += options.max_startups_rate;
1.303 mickey 765: r = arc4random() % 100;
1.124 markus 766:
1.304 djm 767: debug("drop_connection: p %d, r %d", p, r);
1.124 markus 768: return (r < p) ? 1 : 0;
769: }
770:
1.215 markus 771: static void
772: usage(void)
773: {
1.290 markus 774: fprintf(stderr, "%s, %s\n",
1.280 markus 775: SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
1.289 markus 776: fprintf(stderr,
777: "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
778: " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
779: );
1.215 markus 780: exit(1);
781: }
782:
1.294 djm 783: static void
784: send_rexec_state(int fd, Buffer *conf)
785: {
786: Buffer m;
787:
788: debug3("%s: entering fd = %d config len %d", __func__, fd,
789: buffer_len(conf));
790:
791: /*
792: * Protocol from reexec master to child:
793: * string configuration
794: * u_int ephemeral_key_follows
795: * bignum e (only if ephemeral_key_follows == 1)
796: * bignum n "
797: * bignum d "
798: * bignum iqmp "
799: * bignum p "
800: * bignum q "
801: */
802: buffer_init(&m);
803: buffer_put_cstring(&m, buffer_ptr(conf));
804:
1.298 deraadt 805: if (sensitive_data.server_key != NULL &&
1.294 djm 806: sensitive_data.server_key->type == KEY_RSA1) {
807: buffer_put_int(&m, 1);
808: buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
809: buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
810: buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
811: buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
812: buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
813: buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
814: } else
815: buffer_put_int(&m, 0);
816:
817: if (ssh_msg_send(fd, 0, &m) == -1)
818: fatal("%s: ssh_msg_send failed", __func__);
819:
820: buffer_free(&m);
821:
822: debug3("%s: done", __func__);
823: }
824:
825: static void
826: recv_rexec_state(int fd, Buffer *conf)
827: {
828: Buffer m;
829: char *cp;
830: u_int len;
831:
832: debug3("%s: entering fd = %d", __func__, fd);
833:
834: buffer_init(&m);
835:
836: if (ssh_msg_recv(fd, &m) == -1)
837: fatal("%s: ssh_msg_recv failed", __func__);
838: if (buffer_get_char(&m) != 0)
839: fatal("%s: rexec version mismatch", __func__);
840:
841: cp = buffer_get_string(&m, &len);
842: if (conf != NULL)
843: buffer_append(conf, cp, len + 1);
844: xfree(cp);
845:
846: if (buffer_get_int(&m)) {
847: if (sensitive_data.server_key != NULL)
848: key_free(sensitive_data.server_key);
849: sensitive_data.server_key = key_new_private(KEY_RSA1);
850: buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
851: buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
852: buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
853: buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
854: buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
855: buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
856: rsa_generate_additional_parameters(
857: sensitive_data.server_key->rsa);
858: }
859: buffer_free(&m);
860:
861: debug3("%s: done", __func__);
862: }
863:
1.65 deraadt 864: /*
865: * Main program for the daemon.
866: */
1.2 provos 867: int
868: main(int ac, char **av)
1.1 deraadt 869: {
1.64 markus 870: extern char *optarg;
871: extern int optind;
1.329 djm 872: int opt, j, i, on = 1;
1.297 avsm 873: int sock_in = -1, sock_out = -1, newsock = -1;
1.107 deraadt 874: pid_t pid;
1.75 markus 875: socklen_t fromlen;
876: fd_set *fdset;
877: struct sockaddr_storage from;
1.64 markus 878: const char *remote_ip;
879: int remote_port;
880: FILE *f;
1.75 markus 881: struct addrinfo *ai;
882: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.283 markus 883: char *line;
1.75 markus 884: int listen_sock, maxfd;
1.302 djm 885: int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
1.120 markus 886: int startups = 0;
1.278 markus 887: Key *key;
1.230 provos 888: Authctxt *authctxt;
1.151 markus 889: int ret, key_used = 0;
1.294 djm 890: Buffer cfg;
1.64 markus 891:
1.138 markus 892: /* Save argv. */
1.64 markus 893: saved_argv = av;
1.294 djm 894: rexec_argc = ac;
1.313 djm 895:
896: /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
897: sanitise_stdfd();
1.64 markus 898:
899: /* Initialize configuration options to their default values. */
900: initialize_server_options(&options);
901:
902: /* Parse command-line arguments. */
1.294 djm 903: while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
1.64 markus 904: switch (opt) {
1.75 markus 905: case '4':
1.305 djm 906: options.address_family = AF_INET;
1.75 markus 907: break;
908: case '6':
1.305 djm 909: options.address_family = AF_INET6;
1.75 markus 910: break;
1.64 markus 911: case 'f':
912: config_file_name = optarg;
913: break;
914: case 'd':
1.273 markus 915: if (debug_flag == 0) {
1.127 markus 916: debug_flag = 1;
917: options.log_level = SYSLOG_LEVEL_DEBUG1;
1.273 markus 918: } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1.127 markus 919: options.log_level++;
1.64 markus 920: break;
1.135 markus 921: case 'D':
922: no_daemon_flag = 1;
1.192 lebel 923: break;
924: case 'e':
925: log_stderr = 1;
1.135 markus 926: break;
1.64 markus 927: case 'i':
928: inetd_flag = 1;
929: break;
1.294 djm 930: case 'r':
931: rexec_flag = 0;
932: break;
933: case 'R':
934: rexeced_flag = 1;
935: inetd_flag = 1;
936: break;
1.64 markus 937: case 'Q':
1.158 markus 938: /* ignored */
1.64 markus 939: break;
940: case 'q':
941: options.log_level = SYSLOG_LEVEL_QUIET;
942: break;
943: case 'b':
1.327 deraadt 944: options.server_key_bits = (int)strtonum(optarg, 256,
945: 32768, NULL);
1.64 markus 946: break;
947: case 'p':
1.75 markus 948: options.ports_from_cmdline = 1;
1.127 markus 949: if (options.num_ports >= MAX_PORTS) {
950: fprintf(stderr, "too many ports.\n");
951: exit(1);
952: }
1.193 stevesk 953: options.ports[options.num_ports++] = a2port(optarg);
954: if (options.ports[options.num_ports-1] == 0) {
955: fprintf(stderr, "Bad port number.\n");
956: exit(1);
957: }
1.64 markus 958: break;
959: case 'g':
1.197 stevesk 960: if ((options.login_grace_time = convtime(optarg)) == -1) {
961: fprintf(stderr, "Invalid login grace time.\n");
962: exit(1);
963: }
1.64 markus 964: break;
965: case 'k':
1.197 stevesk 966: if ((options.key_regeneration_time = convtime(optarg)) == -1) {
967: fprintf(stderr, "Invalid key regeneration interval.\n");
968: exit(1);
969: }
1.64 markus 970: break;
971: case 'h':
1.134 markus 972: if (options.num_host_key_files >= MAX_HOSTKEYS) {
973: fprintf(stderr, "too many host keys.\n");
974: exit(1);
975: }
976: options.host_key_files[options.num_host_key_files++] = optarg;
1.64 markus 977: break;
1.203 stevesk 978: case 't':
979: test_flag = 1;
980: break;
1.125 markus 981: case 'u':
1.327 deraadt 982: utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1.257 stevesk 983: if (utmp_len > MAXHOSTNAMELEN) {
984: fprintf(stderr, "Invalid utmp length.\n");
985: exit(1);
986: }
1.125 markus 987: break;
1.215 markus 988: case 'o':
1.283 markus 989: line = xstrdup(optarg);
990: if (process_server_config_line(&options, line,
1.215 markus 991: "command-line", 0) != 0)
1.217 deraadt 992: exit(1);
1.283 markus 993: xfree(line);
1.215 markus 994: break;
1.64 markus 995: case '?':
996: default:
1.215 markus 997: usage();
998: break;
1.64 markus 999: }
1000: }
1.294 djm 1001: if (rexeced_flag || inetd_flag)
1002: rexec_flag = 0;
1003: if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1004: fatal("sshd re-exec requires execution with an absolute path");
1005: if (rexeced_flag)
1.296 djm 1006: closefrom(REEXEC_MIN_FREE_FD);
1007: else
1008: closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1.294 djm 1009:
1.180 markus 1010: SSLeay_add_all_algorithms();
1.64 markus 1011:
1.75 markus 1012: /*
1013: * Force logging to stderr until we have loaded the private host
1014: * key (unless started from inetd)
1015: */
1.138 markus 1016: log_init(__progname,
1.224 markus 1017: options.log_level == SYSLOG_LEVEL_NOT_SET ?
1018: SYSLOG_LEVEL_INFO : options.log_level,
1019: options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1020: SYSLOG_FACILITY_AUTH : options.log_facility,
1.261 markus 1021: log_stderr || !inetd_flag);
1.75 markus 1022:
1.294 djm 1023: sensitive_data.server_key = NULL;
1024: sensitive_data.ssh1_host_key = NULL;
1025: sensitive_data.have_ssh1_key = 0;
1026: sensitive_data.have_ssh2_key = 0;
1027:
1028: /* Fetch our configuration */
1029: buffer_init(&cfg);
1030: if (rexeced_flag)
1.296 djm 1031: recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1.294 djm 1032: else
1033: load_server_config(config_file_name, &cfg);
1034:
1035: parse_server_config(&options,
1036: rexeced_flag ? "rexec" : config_file_name, &cfg);
1037:
1038: if (!rexec_flag)
1039: buffer_free(&cfg);
1.64 markus 1040:
1041: /* Fill in default values for those options not explicitly set. */
1042: fill_default_server_options(&options);
1.305 djm 1043:
1044: /* set default channel AF */
1045: channel_set_af(options.address_family);
1.64 markus 1046:
1047: /* Check that there are no remaining arguments. */
1048: if (optind < ac) {
1049: fprintf(stderr, "Extra argument %s.\n", av[optind]);
1050: exit(1);
1051: }
1052:
1053: debug("sshd version %.100s", SSH_VERSION);
1054:
1.134 markus 1055: /* load private host keys */
1.329 djm 1056: sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1.255 deraadt 1057: sizeof(Key *));
1.217 deraadt 1058: for (i = 0; i < options.num_host_key_files; i++)
1.141 markus 1059: sensitive_data.host_keys[i] = NULL;
1.134 markus 1060:
1.217 deraadt 1061: for (i = 0; i < options.num_host_key_files; i++) {
1.179 markus 1062: key = key_load_private(options.host_key_files[i], "", NULL);
1063: sensitive_data.host_keys[i] = key;
1.134 markus 1064: if (key == NULL) {
1.195 markus 1065: error("Could not load host key: %s",
1066: options.host_key_files[i]);
1.179 markus 1067: sensitive_data.host_keys[i] = NULL;
1.134 markus 1068: continue;
1069: }
1.214 deraadt 1070: switch (key->type) {
1.134 markus 1071: case KEY_RSA1:
1072: sensitive_data.ssh1_host_key = key;
1073: sensitive_data.have_ssh1_key = 1;
1074: break;
1075: case KEY_RSA:
1076: case KEY_DSA:
1077: sensitive_data.have_ssh2_key = 1;
1078: break;
1079: }
1.179 markus 1080: debug("private host key: #%d type %d %s", i, key->type,
1081: key_type(key));
1.134 markus 1082: }
1083: if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1.264 itojun 1084: logit("Disabling protocol version 1. Could not load host key");
1.108 markus 1085: options.protocol &= ~SSH_PROTO_1;
1086: }
1.134 markus 1087: if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1.264 itojun 1088: logit("Disabling protocol version 2. Could not load host key");
1.134 markus 1089: options.protocol &= ~SSH_PROTO_2;
1.108 markus 1090: }
1.162 stevesk 1091: if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1.264 itojun 1092: logit("sshd: no hostkeys available -- exiting.");
1.64 markus 1093: exit(1);
1094: }
1095:
1.108 markus 1096: /* Check certain values for sanity. */
1097: if (options.protocol & SSH_PROTO_1) {
1098: if (options.server_key_bits < 512 ||
1099: options.server_key_bits > 32768) {
1100: fprintf(stderr, "Bad server key size.\n");
1101: exit(1);
1102: }
1103: /*
1104: * Check that server and host key lengths differ sufficiently. This
1105: * is necessary to make double encryption work with rsaref. Oh, I
1106: * hate software patents. I dont know if this can go? Niels
1107: */
1108: if (options.server_key_bits >
1.250 deraadt 1109: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1110: SSH_KEY_BITS_RESERVED && options.server_key_bits <
1111: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1112: SSH_KEY_BITS_RESERVED) {
1.108 markus 1113: options.server_key_bits =
1.250 deraadt 1114: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1115: SSH_KEY_BITS_RESERVED;
1.108 markus 1116: debug("Forcing server key to %d bits to make it differ from host key.",
1117: options.server_key_bits);
1118: }
1.244 markus 1119: }
1120:
1121: if (use_privsep) {
1122: struct stat st;
1123:
1.327 deraadt 1124: if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1.244 markus 1125: fatal("Privilege separation user %s does not exist",
1126: SSH_PRIVSEP_USER);
1127: if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1128: (S_ISDIR(st.st_mode) == 0))
1129: fatal("Missing privilege separation directory: %s",
1.247 stevesk 1130: _PATH_PRIVSEP_CHROOT_DIR);
1131: if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1.262 markus 1132: fatal("%s must be owned by root and not group or "
1133: "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1.108 markus 1134: }
1.203 stevesk 1135:
1136: /* Configuration looks good, so exit if in test mode. */
1137: if (test_flag)
1138: exit(0);
1.108 markus 1139:
1.294 djm 1140: if (rexec_flag) {
1.329 djm 1141: rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1.294 djm 1142: for (i = 0; i < rexec_argc; i++) {
1143: debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1144: rexec_argv[i] = saved_argv[i];
1145: }
1146: rexec_argv[rexec_argc] = "-R";
1147: rexec_argv[rexec_argc + 1] = NULL;
1148: }
1149:
1.108 markus 1150: /* Initialize the log (it is reinitialized below in case we forked). */
1.306 dtucker 1151: if (debug_flag && (!inetd_flag || rexeced_flag))
1.64 markus 1152: log_stderr = 1;
1.138 markus 1153: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.64 markus 1154:
1.108 markus 1155: /*
1156: * If not in debugging mode, and not started from inetd, disconnect
1157: * from the controlling terminal, and fork. The original process
1158: * exits.
1159: */
1.135 markus 1160: if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1.1 deraadt 1161: #ifdef TIOCNOTTY
1.64 markus 1162: int fd;
1.1 deraadt 1163: #endif /* TIOCNOTTY */
1.64 markus 1164: if (daemon(0, 0) < 0)
1165: fatal("daemon() failed: %.200s", strerror(errno));
1166:
1167: /* Disconnect from the controlling tty. */
1.1 deraadt 1168: #ifdef TIOCNOTTY
1.165 itojun 1169: fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1.64 markus 1170: if (fd >= 0) {
1171: (void) ioctl(fd, TIOCNOTTY, NULL);
1172: close(fd);
1173: }
1174: #endif /* TIOCNOTTY */
1175: }
1176: /* Reinitialize the log (because of the fork above). */
1.138 markus 1177: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.64 markus 1178:
1179: /* Initialize the random number generator. */
1180: arc4random_stir();
1181:
1182: /* Chdir to the root directory so that the current disk can be
1183: unmounted if desired. */
1184: chdir("/");
1.217 deraadt 1185:
1.178 markus 1186: /* ignore SIGPIPE */
1187: signal(SIGPIPE, SIG_IGN);
1.64 markus 1188:
1189: /* Start listening for a socket, unless started from inetd. */
1190: if (inetd_flag) {
1.294 djm 1191: int fd;
1192:
1.123 djm 1193: startup_pipe = -1;
1.294 djm 1194: if (rexeced_flag) {
1.296 djm 1195: close(REEXEC_CONFIG_PASS_FD);
1.294 djm 1196: sock_in = sock_out = dup(STDIN_FILENO);
1197: if (!debug_flag) {
1.296 djm 1198: startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1199: close(REEXEC_STARTUP_PIPE_FD);
1.294 djm 1200: }
1201: } else {
1202: sock_in = dup(STDIN_FILENO);
1203: sock_out = dup(STDOUT_FILENO);
1204: }
1.108 markus 1205: /*
1206: * We intentionally do not close the descriptors 0, 1, and 2
1.294 djm 1207: * as our code for setting the descriptors won't work if
1.108 markus 1208: * ttyfd happens to be one of those.
1209: */
1.294 djm 1210: if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1211: dup2(fd, STDIN_FILENO);
1212: dup2(fd, STDOUT_FILENO);
1213: if (fd > STDOUT_FILENO)
1214: close(fd);
1215: }
1.64 markus 1216: debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1.294 djm 1217: if ((options.protocol & SSH_PROTO_1) &&
1218: sensitive_data.server_key == NULL)
1.174 deraadt 1219: generate_ephemeral_server_key();
1.64 markus 1220: } else {
1.75 markus 1221: for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1222: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1223: continue;
1224: if (num_listen_socks >= MAX_LISTEN_SOCKS)
1225: fatal("Too many listen sockets. "
1226: "Enlarge MAX_LISTEN_SOCKS");
1.308 dtucker 1227: if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1.75 markus 1228: ntop, sizeof(ntop), strport, sizeof(strport),
1.308 dtucker 1229: NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1230: error("getnameinfo failed: %.100s",
1231: (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1232: strerror(errno));
1.75 markus 1233: continue;
1234: }
1235: /* Create socket for listening. */
1.265 markus 1236: listen_sock = socket(ai->ai_family, ai->ai_socktype,
1237: ai->ai_protocol);
1.75 markus 1238: if (listen_sock < 0) {
1239: /* kernel may not support ipv6 */
1240: verbose("socket: %.100s", strerror(errno));
1241: continue;
1242: }
1.293 djm 1243: if (set_nonblock(listen_sock) == -1) {
1.286 markus 1244: close(listen_sock);
1245: continue;
1246: }
1.75 markus 1247: /*
1.258 stevesk 1248: * Set socket options.
1249: * Allow local port reuse in TIME_WAIT.
1.75 markus 1250: */
1.258 stevesk 1251: if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1252: &on, sizeof(on)) == -1)
1253: error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1.75 markus 1254:
1255: debug("Bind to port %s on %s.", strport, ntop);
1256:
1257: /* Bind the socket to the desired port. */
1258: if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1259: error("Bind to port %s on %s failed: %.200s.",
1260: strport, ntop, strerror(errno));
1261: close(listen_sock);
1262: continue;
1263: }
1264: listen_socks[num_listen_socks] = listen_sock;
1265: num_listen_socks++;
1266:
1267: /* Start listening on the port. */
1.325 djm 1268: if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1269: fatal("listen on [%s]:%s: %.100s",
1270: ntop, strport, strerror(errno));
1.264 itojun 1271: logit("Server listening on %s port %s.", ntop, strport);
1.64 markus 1272: }
1.75 markus 1273: freeaddrinfo(options.listen_addrs);
1274:
1275: if (!num_listen_socks)
1276: fatal("Cannot bind any address.");
1277:
1.201 markus 1278: if (options.protocol & SSH_PROTO_1)
1279: generate_ephemeral_server_key();
1280:
1281: /*
1282: * Arrange to restart on SIGHUP. The handler needs
1283: * listen_sock.
1284: */
1285: signal(SIGHUP, sighup_handler);
1286:
1287: signal(SIGTERM, sigterm_handler);
1288: signal(SIGQUIT, sigterm_handler);
1289:
1290: /* Arrange SIGCHLD to be caught. */
1291: signal(SIGCHLD, main_sigchld_handler);
1292:
1293: /* Write out the pid file after the sigterm handler is setup */
1.64 markus 1294: if (!debug_flag) {
1.66 markus 1295: /*
1.136 todd 1296: * Record our pid in /var/run/sshd.pid to make it
1297: * easier to kill the correct sshd. We don't want to
1298: * do this before the bind above because the bind will
1.66 markus 1299: * fail if there already is a daemon, and this will
1300: * overwrite any old pid in the file.
1301: */
1.112 markus 1302: f = fopen(options.pid_file, "w");
1.270 djm 1303: if (f == NULL) {
1304: error("Couldn't create pid file \"%s\": %s",
1305: options.pid_file, strerror(errno));
1306: } else {
1.245 mpech 1307: fprintf(f, "%ld\n", (long) getpid());
1.64 markus 1308: fclose(f);
1309: }
1310: }
1311:
1.75 markus 1312: /* setup fd set for listen */
1.120 markus 1313: fdset = NULL;
1.75 markus 1314: maxfd = 0;
1315: for (i = 0; i < num_listen_socks; i++)
1316: if (listen_socks[i] > maxfd)
1317: maxfd = listen_socks[i];
1.120 markus 1318: /* pipes connected to unauthenticated childs */
1.329 djm 1319: startup_pipes = xcalloc(options.max_startups, sizeof(int));
1.120 markus 1320: for (i = 0; i < options.max_startups; i++)
1321: startup_pipes[i] = -1;
1.75 markus 1322:
1.66 markus 1323: /*
1324: * Stay listening for connections until the system crashes or
1325: * the daemon is killed with a signal.
1326: */
1.64 markus 1327: for (;;) {
1328: if (received_sighup)
1329: sighup_restart();
1.120 markus 1330: if (fdset != NULL)
1331: xfree(fdset);
1.329 djm 1332: fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1333: sizeof(fd_mask));
1.120 markus 1334:
1.75 markus 1335: for (i = 0; i < num_listen_socks; i++)
1336: FD_SET(listen_socks[i], fdset);
1.120 markus 1337: for (i = 0; i < options.max_startups; i++)
1338: if (startup_pipes[i] != -1)
1339: FD_SET(startup_pipes[i], fdset);
1340:
1341: /* Wait in select until there is a connection. */
1.151 markus 1342: ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1343: if (ret < 0 && errno != EINTR)
1344: error("select: %.100s", strerror(errno));
1.199 markus 1345: if (received_sigterm) {
1.264 itojun 1346: logit("Received signal %d; terminating.",
1.213 itojun 1347: (int) received_sigterm);
1.199 markus 1348: close_listen_socks();
1349: unlink(options.pid_file);
1350: exit(255);
1351: }
1.151 markus 1352: if (key_used && key_do_regen) {
1.174 deraadt 1353: generate_ephemeral_server_key();
1.151 markus 1354: key_used = 0;
1355: key_do_regen = 0;
1356: }
1357: if (ret < 0)
1.75 markus 1358: continue;
1.151 markus 1359:
1.120 markus 1360: for (i = 0; i < options.max_startups; i++)
1361: if (startup_pipes[i] != -1 &&
1362: FD_ISSET(startup_pipes[i], fdset)) {
1363: /*
1364: * the read end of the pipe is ready
1365: * if the child has closed the pipe
1.143 markus 1366: * after successful authentication
1.120 markus 1367: * or if the child has died
1368: */
1369: close(startup_pipes[i]);
1370: startup_pipes[i] = -1;
1371: startups--;
1372: }
1.75 markus 1373: for (i = 0; i < num_listen_socks; i++) {
1374: if (!FD_ISSET(listen_socks[i], fdset))
1.70 provos 1375: continue;
1.120 markus 1376: fromlen = sizeof(from);
1.327 deraadt 1377: newsock = accept(listen_socks[i],
1378: (struct sockaddr *)&from, &fromlen);
1.120 markus 1379: if (newsock < 0) {
1380: if (errno != EINTR && errno != EWOULDBLOCK)
1381: error("accept: %.100s", strerror(errno));
1.286 markus 1382: continue;
1383: }
1.293 djm 1384: if (unset_nonblock(newsock) == -1) {
1.286 markus 1385: close(newsock);
1.120 markus 1386: continue;
1387: }
1.124 markus 1388: if (drop_connection(startups) == 1) {
1389: debug("drop connection #%d", startups);
1.120 markus 1390: close(newsock);
1391: continue;
1392: }
1393: if (pipe(startup_p) == -1) {
1394: close(newsock);
1395: continue;
1396: }
1397:
1.294 djm 1398: if (rexec_flag && socketpair(AF_UNIX,
1399: SOCK_STREAM, 0, config_s) == -1) {
1400: error("reexec socketpair: %s",
1401: strerror(errno));
1402: close(newsock);
1403: close(startup_p[0]);
1404: close(startup_p[1]);
1405: continue;
1406: }
1407:
1.120 markus 1408: for (j = 0; j < options.max_startups; j++)
1409: if (startup_pipes[j] == -1) {
1410: startup_pipes[j] = startup_p[0];
1411: if (maxfd < startup_p[0])
1412: maxfd = startup_p[0];
1413: startups++;
1414: break;
1415: }
1.161 stevesk 1416:
1.66 markus 1417: /*
1.120 markus 1418: * Got connection. Fork a child to handle it, unless
1419: * we are in debugging mode.
1.66 markus 1420: */
1.120 markus 1421: if (debug_flag) {
1.66 markus 1422: /*
1.120 markus 1423: * In debugging mode. Close the listening
1424: * socket, and start processing the
1425: * connection without forking.
1.66 markus 1426: */
1.120 markus 1427: debug("Server will not fork when running in debugging mode.");
1.75 markus 1428: close_listen_socks();
1.64 markus 1429: sock_in = newsock;
1430: sock_out = newsock;
1.294 djm 1431: close(startup_p[0]);
1432: close(startup_p[1]);
1.122 deraadt 1433: startup_pipe = -1;
1.120 markus 1434: pid = getpid();
1.294 djm 1435: if (rexec_flag) {
1436: send_rexec_state(config_s[0],
1437: &cfg);
1438: close(config_s[0]);
1439: }
1.64 markus 1440: break;
1.120 markus 1441: } else {
1442: /*
1443: * Normal production daemon. Fork, and have
1444: * the child process the connection. The
1445: * parent continues listening.
1446: */
1447: if ((pid = fork()) == 0) {
1448: /*
1.327 deraadt 1449: * Child. Close the listening and
1450: * max_startup sockets. Start using
1451: * the accepted socket. Reinitialize
1452: * logging (since our pid has changed).
1453: * We break out of the loop to handle
1.120 markus 1454: * the connection.
1455: */
1456: startup_pipe = startup_p[1];
1.211 markus 1457: close_startup_pipes();
1.120 markus 1458: close_listen_socks();
1459: sock_in = newsock;
1460: sock_out = newsock;
1.327 deraadt 1461: log_init(__progname,
1462: options.log_level,
1463: options.log_facility,
1464: log_stderr);
1.302 djm 1465: if (rexec_flag)
1466: close(config_s[0]);
1.120 markus 1467: break;
1468: }
1.64 markus 1469: }
1470:
1.120 markus 1471: /* Parent. Stay in the loop. */
1472: if (pid < 0)
1473: error("fork: %.100s", strerror(errno));
1474: else
1.245 mpech 1475: debug("Forked child %ld.", (long)pid);
1.120 markus 1476:
1477: close(startup_p[1]);
1.1 deraadt 1478:
1.294 djm 1479: if (rexec_flag) {
1480: send_rexec_state(config_s[0], &cfg);
1481: close(config_s[0]);
1482: close(config_s[1]);
1483: }
1484:
1.327 deraadt 1485: /*
1486: * Mark that the key has been used (it
1487: * was "given" to the child).
1488: */
1.151 markus 1489: if ((options.protocol & SSH_PROTO_1) &&
1490: key_used == 0) {
1491: /* Schedule server key regeneration alarm. */
1492: signal(SIGALRM, key_regeneration_alarm);
1493: alarm(options.key_regeneration_time);
1494: key_used = 1;
1495: }
1.1 deraadt 1496:
1.120 markus 1497: arc4random_stir();
1498: close(newsock);
1499: }
1.75 markus 1500: /* child process check (or debug mode) */
1501: if (num_listen_socks < 0)
1502: break;
1.64 markus 1503: }
1.1 deraadt 1504: }
1505:
1.64 markus 1506: /* This is the child processing a new connection. */
1.288 markus 1507: setproctitle("%s", "[accepted]");
1.294 djm 1508:
1.300 markus 1509: /*
1510: * Create a new session and process group since the 4.4BSD
1511: * setlogin() affects the entire process group. We don't
1512: * want the child to be able to affect the parent.
1513: */
1514: if (!debug_flag && !inetd_flag && setsid() < 0)
1515: error("setsid: %.100s", strerror(errno));
1516:
1.294 djm 1517: if (rexec_flag) {
1518: int fd;
1519:
1.296 djm 1520: debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1521: sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1.294 djm 1522: dup2(newsock, STDIN_FILENO);
1523: dup2(STDIN_FILENO, STDOUT_FILENO);
1524: if (startup_pipe == -1)
1.296 djm 1525: close(REEXEC_STARTUP_PIPE_FD);
1.294 djm 1526: else
1.296 djm 1527: dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1.294 djm 1528:
1.296 djm 1529: dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1.294 djm 1530: close(config_s[1]);
1.301 dtucker 1531: if (startup_pipe != -1)
1532: close(startup_pipe);
1.296 djm 1533:
1.294 djm 1534: execv(rexec_argv[0], rexec_argv);
1535:
1536: /* Reexec has failed, fall back and continue */
1537: error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1.296 djm 1538: recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1.294 djm 1539: log_init(__progname, options.log_level,
1540: options.log_facility, log_stderr);
1541:
1542: /* Clean up fds */
1.296 djm 1543: startup_pipe = REEXEC_STARTUP_PIPE_FD;
1.294 djm 1544: close(config_s[1]);
1.296 djm 1545: close(REEXEC_CONFIG_PASS_FD);
1546: newsock = sock_out = sock_in = dup(STDIN_FILENO);
1.294 djm 1547: if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1548: dup2(fd, STDIN_FILENO);
1549: dup2(fd, STDOUT_FILENO);
1550: if (fd > STDERR_FILENO)
1551: close(fd);
1552: }
1.296 djm 1553: debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1554: sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1.294 djm 1555: }
1.64 markus 1556:
1.66 markus 1557: /*
1558: * Disable the key regeneration alarm. We will not regenerate the
1559: * key since we are no longer in a position to give it to anyone. We
1560: * will not restart on SIGHUP since it no longer makes sense.
1561: */
1.64 markus 1562: alarm(0);
1563: signal(SIGALRM, SIG_DFL);
1564: signal(SIGHUP, SIG_DFL);
1565: signal(SIGTERM, SIG_DFL);
1566: signal(SIGQUIT, SIG_DFL);
1567: signal(SIGCHLD, SIG_DFL);
1.150 markus 1568:
1.66 markus 1569: /*
1570: * Register our connection. This turns encryption off because we do
1571: * not have a key.
1572: */
1.64 markus 1573: packet_set_connection(sock_in, sock_out);
1.312 markus 1574: packet_set_server();
1.309 djm 1575:
1576: /* Set SO_KEEPALIVE if requested. */
1577: if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1578: setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1579: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.1 deraadt 1580:
1.310 markus 1581: if ((remote_port = get_remote_port()) < 0) {
1582: debug("get_remote_port failed");
1583: cleanup_exit(255);
1584: }
1.316 dtucker 1585:
1586: /*
1587: * We use get_canonical_hostname with usedns = 0 instead of
1588: * get_remote_ipaddr here so IP options will be checked.
1589: */
1.331 ! markus 1590: (void) get_canonical_hostname(0);
! 1591: /*
! 1592: * The rest of the code depends on the fact that
! 1593: * get_remote_ipaddr() caches the remote ip, even if
! 1594: * the socket goes away.
! 1595: */
! 1596: remote_ip = get_remote_ipaddr();
1.52 markus 1597:
1.209 markus 1598: #ifdef LIBWRAP
1.64 markus 1599: /* Check whether logins are denied from this host. */
1.295 djm 1600: if (packet_connection_is_on_socket()) {
1.64 markus 1601: struct request_info req;
1.37 dugsong 1602:
1.204 camield 1603: request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1.64 markus 1604: fromhost(&req);
1.37 dugsong 1605:
1.64 markus 1606: if (!hosts_access(&req)) {
1.209 markus 1607: debug("Connection refused by tcp wrapper");
1.182 markus 1608: refuse(&req);
1.209 markus 1609: /* NOTREACHED */
1610: fatal("libwrap refuse returns");
1.64 markus 1611: }
1612: }
1.75 markus 1613: #endif /* LIBWRAP */
1.209 markus 1614:
1.64 markus 1615: /* Log the connection. */
1616: verbose("Connection from %.500s port %d", remote_ip, remote_port);
1.1 deraadt 1617:
1.66 markus 1618: /*
1.317 djm 1619: * We don't want to listen forever unless the other side
1.66 markus 1620: * successfully authenticates itself. So we set up an alarm which is
1621: * cleared after successful authentication. A limit of zero
1.317 djm 1622: * indicates no limit. Note that we don't set the alarm in debugging
1.66 markus 1623: * mode; it is just annoying to have the server exit just when you
1624: * are about to discover the bug.
1625: */
1.64 markus 1626: signal(SIGALRM, grace_alarm_handler);
1627: if (!debug_flag)
1628: alarm(options.login_grace_time);
1629:
1.96 markus 1630: sshd_exchange_identification(sock_in, sock_out);
1.275 markus 1631:
1.64 markus 1632: packet_set_nonblocking();
1.1 deraadt 1633:
1.278 markus 1634: /* allocate authentication context */
1.329 djm 1635: authctxt = xcalloc(1, sizeof(*authctxt));
1.278 markus 1636:
1637: /* XXX global for cleanup, access from other modules */
1638: the_authctxt = authctxt;
1639:
1.307 otto 1640: /* prepare buffer to collect messages to display to user after login */
1641: buffer_init(&loginmsg);
1642:
1.237 markus 1643: if (use_privsep)
1.278 markus 1644: if (privsep_preauth(authctxt) == 1)
1.237 markus 1645: goto authenticated;
1.231 provos 1646:
1.77 markus 1647: /* perform the key exchange */
1648: /* authenticate user and start session */
1.98 markus 1649: if (compat20) {
1650: do_ssh2_kex();
1.278 markus 1651: do_authentication2(authctxt);
1.98 markus 1652: } else {
1653: do_ssh1_kex();
1.278 markus 1654: do_authentication(authctxt);
1.98 markus 1655: }
1.237 markus 1656: /*
1657: * If we use privilege separation, the unprivileged child transfers
1658: * the current keystate and exits
1659: */
1660: if (use_privsep) {
1.242 mouring 1661: mm_send_keystate(pmonitor);
1.231 provos 1662: exit(0);
1.237 markus 1663: }
1.231 provos 1664:
1665: authenticated:
1.318 djm 1666: /*
1667: * Cancel the alarm we set to limit the time taken for
1668: * authentication.
1669: */
1670: alarm(0);
1671: signal(SIGALRM, SIG_DFL);
1672: if (startup_pipe != -1) {
1673: close(startup_pipe);
1674: startup_pipe = -1;
1675: }
1676:
1.234 markus 1677: /*
1.231 provos 1678: * In privilege separation, we fork another child and prepare
1679: * file descriptor passing.
1680: */
1681: if (use_privsep) {
1.237 markus 1682: privsep_postauth(authctxt);
1683: /* the monitor process [priv] will not return */
1.231 provos 1684: if (!compat20)
1685: destroy_sensitive_data();
1686: }
1.230 provos 1687:
1.278 markus 1688: /* Start session. */
1.230 provos 1689: do_authenticated(authctxt);
1690:
1.64 markus 1691: /* The connection has been terminated. */
1692: verbose("Closing connection to %.100s", remote_ip);
1693: packet_close();
1.231 provos 1694:
1695: if (use_privsep)
1696: mm_terminate();
1697:
1.64 markus 1698: exit(0);
1.1 deraadt 1699: }
1700:
1.65 deraadt 1701: /*
1.229 markus 1702: * Decrypt session_key_int using our private server key and private host key
1703: * (key with larger modulus first).
1704: */
1.231 provos 1705: int
1.229 markus 1706: ssh1_session_key(BIGNUM *session_key_int)
1707: {
1708: int rsafail = 0;
1709:
1.327 deraadt 1710: if (BN_cmp(sensitive_data.server_key->rsa->n,
1711: sensitive_data.ssh1_host_key->rsa->n) > 0) {
1.229 markus 1712: /* Server key has bigger modulus. */
1713: if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1.327 deraadt 1714: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1715: SSH_KEY_BITS_RESERVED) {
1716: fatal("do_connection: %s: "
1717: "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1.229 markus 1718: get_remote_ipaddr(),
1719: BN_num_bits(sensitive_data.server_key->rsa->n),
1720: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1721: SSH_KEY_BITS_RESERVED);
1722: }
1723: if (rsa_private_decrypt(session_key_int, session_key_int,
1724: sensitive_data.server_key->rsa) <= 0)
1725: rsafail++;
1726: if (rsa_private_decrypt(session_key_int, session_key_int,
1727: sensitive_data.ssh1_host_key->rsa) <= 0)
1728: rsafail++;
1729: } else {
1730: /* Host key has bigger modulus (or they are equal). */
1731: if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1.327 deraadt 1732: BN_num_bits(sensitive_data.server_key->rsa->n) +
1733: SSH_KEY_BITS_RESERVED) {
1734: fatal("do_connection: %s: "
1735: "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1.229 markus 1736: get_remote_ipaddr(),
1737: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1738: BN_num_bits(sensitive_data.server_key->rsa->n),
1739: SSH_KEY_BITS_RESERVED);
1740: }
1741: if (rsa_private_decrypt(session_key_int, session_key_int,
1742: sensitive_data.ssh1_host_key->rsa) < 0)
1743: rsafail++;
1744: if (rsa_private_decrypt(session_key_int, session_key_int,
1745: sensitive_data.server_key->rsa) < 0)
1746: rsafail++;
1747: }
1748: return (rsafail);
1749: }
1750: /*
1.77 markus 1751: * SSH1 key exchange
1.65 deraadt 1752: */
1.200 itojun 1753: static void
1.142 markus 1754: do_ssh1_kex(void)
1.1 deraadt 1755: {
1.64 markus 1756: int i, len;
1.159 markus 1757: int rsafail = 0;
1.64 markus 1758: BIGNUM *session_key_int;
1.140 markus 1759: u_char session_key[SSH_SESSION_KEY_LENGTH];
1760: u_char cookie[8];
1761: u_int cipher_type, auth_mask, protocol_flags;
1.254 deraadt 1762: u_int32_t rnd = 0;
1.64 markus 1763:
1.66 markus 1764: /*
1765: * Generate check bytes that the client must send back in the user
1766: * packet in order for it to be accepted; this is used to defy ip
1767: * spoofing attacks. Note that this only works against somebody
1768: * doing IP spoofing from a remote machine; any machine on the local
1769: * network can still see outgoing packets and catch the random
1770: * cookie. This only affects rhosts authentication, and this is one
1771: * of the reasons why it is inherently insecure.
1772: */
1.64 markus 1773: for (i = 0; i < 8; i++) {
1774: if (i % 4 == 0)
1.254 deraadt 1775: rnd = arc4random();
1776: cookie[i] = rnd & 0xff;
1777: rnd >>= 8;
1.64 markus 1778: }
1779:
1.66 markus 1780: /*
1781: * Send our public key. We include in the packet 64 bits of random
1782: * data that must be matched in the reply in order to prevent IP
1783: * spoofing.
1784: */
1.64 markus 1785: packet_start(SSH_SMSG_PUBLIC_KEY);
1786: for (i = 0; i < 8; i++)
1.77 markus 1787: packet_put_char(cookie[i]);
1.64 markus 1788:
1789: /* Store our public server RSA key. */
1.134 markus 1790: packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1791: packet_put_bignum(sensitive_data.server_key->rsa->e);
1792: packet_put_bignum(sensitive_data.server_key->rsa->n);
1.64 markus 1793:
1794: /* Store our public host RSA key. */
1.134 markus 1795: packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1796: packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1797: packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1.64 markus 1798:
1799: /* Put protocol flags. */
1800: packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1801:
1802: /* Declare which ciphers we support. */
1.131 markus 1803: packet_put_int(cipher_mask_ssh1(0));
1.64 markus 1804:
1805: /* Declare supported authentication types. */
1806: auth_mask = 0;
1807: if (options.rhosts_rsa_authentication)
1808: auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1809: if (options.rsa_authentication)
1810: auth_mask |= 1 << SSH_AUTH_RSA;
1.196 markus 1811: if (options.challenge_response_authentication == 1)
1.64 markus 1812: auth_mask |= 1 << SSH_AUTH_TIS;
1813: if (options.password_authentication)
1814: auth_mask |= 1 << SSH_AUTH_PASSWORD;
1815: packet_put_int(auth_mask);
1816:
1817: /* Send the packet and wait for it to be sent. */
1818: packet_send();
1819: packet_write_wait();
1820:
1.134 markus 1821: debug("Sent %d bit server key and %d bit host key.",
1822: BN_num_bits(sensitive_data.server_key->rsa->n),
1823: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1.64 markus 1824:
1825: /* Read clients reply (cipher type and session key). */
1.222 markus 1826: packet_read_expect(SSH_CMSG_SESSION_KEY);
1.64 markus 1827:
1.69 markus 1828: /* Get cipher type and check whether we accept this. */
1.64 markus 1829: cipher_type = packet_get_char();
1.69 markus 1830:
1.131 markus 1831: if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1.69 markus 1832: packet_disconnect("Warning: client selects unsupported cipher.");
1.64 markus 1833:
1834: /* Get check bytes from the packet. These must match those we
1835: sent earlier with the public key packet. */
1836: for (i = 0; i < 8; i++)
1.77 markus 1837: if (cookie[i] != packet_get_char())
1.64 markus 1838: packet_disconnect("IP Spoofing check bytes do not match.");
1839:
1840: debug("Encryption type: %.200s", cipher_name(cipher_type));
1841:
1842: /* Get the encrypted integer. */
1.218 markus 1843: if ((session_key_int = BN_new()) == NULL)
1844: fatal("do_ssh1_kex: BN_new failed");
1.221 markus 1845: packet_get_bignum(session_key_int);
1.64 markus 1846:
1847: protocol_flags = packet_get_int();
1848: packet_set_protocol_flags(protocol_flags);
1.220 markus 1849: packet_check_eom();
1.64 markus 1850:
1.229 markus 1851: /* Decrypt session_key_int using host/server keys */
1.231 provos 1852: rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1853:
1.66 markus 1854: /*
1855: * Extract session key from the decrypted integer. The key is in the
1856: * least significant 256 bits of the integer; the first byte of the
1857: * key is in the highest bits.
1858: */
1.159 markus 1859: if (!rsafail) {
1860: BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1861: len = BN_num_bytes(session_key_int);
1.311 djm 1862: if (len < 0 || (u_int)len > sizeof(session_key)) {
1.159 markus 1863: error("do_connection: bad session key len from %s: "
1.165 itojun 1864: "session_key_int %d > sizeof(session_key) %lu",
1865: get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1.159 markus 1866: rsafail++;
1867: } else {
1868: memset(session_key, 0, sizeof(session_key));
1869: BN_bn2bin(session_key_int,
1870: session_key + sizeof(session_key) - len);
1.169 markus 1871:
1.291 djm 1872: derive_ssh1_session_id(
1.298 deraadt 1873: sensitive_data.ssh1_host_key->rsa->n,
1.291 djm 1874: sensitive_data.server_key->rsa->n,
1875: cookie, session_id);
1.169 markus 1876: /*
1877: * Xor the first 16 bytes of the session key with the
1878: * session id.
1879: */
1880: for (i = 0; i < 16; i++)
1881: session_key[i] ^= session_id[i];
1.159 markus 1882: }
1883: }
1884: if (rsafail) {
1.169 markus 1885: int bytes = BN_num_bytes(session_key_int);
1.227 stevesk 1886: u_char *buf = xmalloc(bytes);
1.169 markus 1887: MD5_CTX md;
1888:
1.264 itojun 1889: logit("do_connection: generating a fake encryption key");
1.169 markus 1890: BN_bn2bin(session_key_int, buf);
1891: MD5_Init(&md);
1892: MD5_Update(&md, buf, bytes);
1893: MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1894: MD5_Final(session_key, &md);
1895: MD5_Init(&md);
1896: MD5_Update(&md, session_key, 16);
1897: MD5_Update(&md, buf, bytes);
1898: MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1899: MD5_Final(session_key + 16, &md);
1900: memset(buf, 0, bytes);
1901: xfree(buf);
1.170 markus 1902: for (i = 0; i < 16; i++)
1903: session_id[i] = session_key[i] ^ session_key[i + 16];
1.159 markus 1904: }
1.231 provos 1905: /* Destroy the private and public keys. No longer. */
1.169 markus 1906: destroy_sensitive_data();
1907:
1.231 provos 1908: if (use_privsep)
1909: mm_ssh1_session_id(session_id);
1910:
1.77 markus 1911: /* Destroy the decrypted integer. It is no longer needed. */
1912: BN_clear_free(session_key_int);
1.64 markus 1913:
1914: /* Set the session key. From this on all communications will be encrypted. */
1915: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1916:
1917: /* Destroy our copy of the session key. It is no longer needed. */
1918: memset(session_key, 0, sizeof(session_key));
1919:
1920: debug("Received session key; encryption turned on.");
1921:
1.243 deraadt 1922: /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1.64 markus 1923: packet_start(SSH_SMSG_SUCCESS);
1924: packet_send();
1925: packet_write_wait();
1.98 markus 1926: }
1927:
1928: /*
1929: * SSH2 key exchange: diffie-hellman-group1-sha1
1930: */
1.200 itojun 1931: static void
1.142 markus 1932: do_ssh2_kex(void)
1.98 markus 1933: {
1934: Kex *kex;
1.102 markus 1935:
1936: if (options.ciphers != NULL) {
1.105 markus 1937: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1.102 markus 1938: myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1.166 markus 1939: }
1.184 stevesk 1940: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1941: compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1942: myproposal[PROPOSAL_ENC_ALGS_STOC] =
1943: compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1944:
1.166 markus 1945: if (options.macs != NULL) {
1946: myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1947: myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1.246 markus 1948: }
1.312 markus 1949: if (options.compression == COMP_NONE) {
1.246 markus 1950: myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1951: myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1.312 markus 1952: } else if (options.compression == COMP_DELAYED) {
1953: myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1954: myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
1.102 markus 1955: }
1.327 deraadt 1956:
1.134 markus 1957: myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1958:
1.189 markus 1959: /* start key exchange */
1.188 markus 1960: kex = kex_setup(myproposal);
1.263 markus 1961: kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
1.292 djm 1962: kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
1.263 markus 1963: kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1.324 djm 1964: kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
1.186 markus 1965: kex->server = 1;
1966: kex->client_version_string=client_version_string;
1967: kex->server_version_string=server_version_string;
1968: kex->load_host_key=&get_hostkey_by_type;
1.231 provos 1969: kex->host_key_index=&get_hostkey_index;
1.129 provos 1970:
1.189 markus 1971: xxx_kex = kex;
1972:
1.190 markus 1973: dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
1.187 markus 1974:
1975: session_id2 = kex->session_id;
1976: session_id2_len = kex->session_id_len;
1.129 provos 1977:
1978: #ifdef DEBUG_KEXDH
1979: /* send 1st encrypted/maced/compressed message */
1980: packet_start(SSH2_MSG_IGNORE);
1981: packet_put_cstring("markus");
1982: packet_send();
1983: packet_write_wait();
1984: #endif
1.186 markus 1985: debug("KEX done");
1.278 markus 1986: }
1987:
1988: /* server specific fatal cleanup */
1989: void
1990: cleanup_exit(int i)
1991: {
1992: if (the_authctxt)
1993: do_cleanup(the_authctxt);
1994: _exit(i);
1.1 deraadt 1995: }
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