Annotation of src/usr.bin/ssh/sshd.c, Revision 1.332
1.332 ! stevesk 1: /* $OpenBSD: sshd.c,v 1.331 2006/06/01 09:21:48 markus 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"
1.332 ! stevesk 92: #include "version.h"
1.1 deraadt 93:
94: #ifdef LIBWRAP
95: #include <tcpd.h>
96: #include <syslog.h>
97: int allow_severity = LOG_INFO;
98: int deny_severity = LOG_WARNING;
99: #endif /* LIBWRAP */
100:
101: #ifndef O_NOCTTY
102: #define O_NOCTTY 0
103: #endif
104:
1.296 djm 105: /* Re-exec fds */
106: #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
107: #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
108: #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
109: #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
110:
1.138 markus 111: extern char *__progname;
112:
1.1 deraadt 113: /* Server configuration options. */
114: ServerOptions options;
115:
116: /* Name of the server configuration file. */
1.154 markus 117: char *config_file_name = _PATH_SERVER_CONFIG_FILE;
1.1 deraadt 118:
1.105 markus 119: /*
1.65 deraadt 120: * Debug mode flag. This can be set on the command line. If debug
121: * mode is enabled, extra debugging output will be sent to the system
122: * log, the daemon will not go to background, and will exit after processing
123: * the first connection.
124: */
1.1 deraadt 125: int debug_flag = 0;
126:
1.203 stevesk 127: /* Flag indicating that the daemon should only test the configuration and keys. */
128: int test_flag = 0;
129:
1.1 deraadt 130: /* Flag indicating that the daemon is being started from inetd. */
131: int inetd_flag = 0;
132:
1.135 markus 133: /* Flag indicating that sshd should not detach and become a daemon. */
134: int no_daemon_flag = 0;
135:
1.47 markus 136: /* debug goes to stderr unless inetd_flag is set */
137: int log_stderr = 0;
138:
1.1 deraadt 139: /* Saved arguments to main(). */
140: char **saved_argv;
141:
1.294 djm 142: /* re-exec */
143: int rexeced_flag = 0;
144: int rexec_flag = 1;
145: int rexec_argc = 0;
146: char **rexec_argv;
147:
1.66 markus 148: /*
1.75 markus 149: * The sockets that the server is listening; this is used in the SIGHUP
150: * signal handler.
1.66 markus 151: */
1.75 markus 152: #define MAX_LISTEN_SOCKS 16
153: int listen_socks[MAX_LISTEN_SOCKS];
154: int num_listen_socks = 0;
1.1 deraadt 155:
1.66 markus 156: /*
157: * the client's version string, passed by sshd2 in compat mode. if != NULL,
158: * sshd will skip the version-number exchange
159: */
1.61 markus 160: char *client_version_string = NULL;
1.96 markus 161: char *server_version_string = NULL;
1.1 deraadt 162:
1.189 markus 163: /* for rekeying XXX fixme */
164: Kex *xxx_kex;
165:
1.66 markus 166: /*
167: * Any really sensitive data in the application is contained in this
168: * structure. The idea is that this structure could be locked into memory so
169: * that the pages do not get written into swap. However, there are some
170: * problems. The private key contains BIGNUMs, and we do not (in principle)
171: * have access to the internals of them, and locking just the structure is
172: * not very useful. Currently, memory locking is not implemented.
173: */
1.64 markus 174: struct {
1.174 deraadt 175: Key *server_key; /* ephemeral server key */
1.134 markus 176: Key *ssh1_host_key; /* ssh1 host key */
177: Key **host_keys; /* all private host keys */
178: int have_ssh1_key;
179: int have_ssh2_key;
1.169 markus 180: u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
1.1 deraadt 181: } sensitive_data;
182:
1.66 markus 183: /*
1.151 markus 184: * Flag indicating whether the RSA server key needs to be regenerated.
185: * Is set in the SIGALRM handler and cleared when the key is regenerated.
1.66 markus 186: */
1.212 markus 187: static volatile sig_atomic_t key_do_regen = 0;
1.1 deraadt 188:
1.199 markus 189: /* This is set to true when a signal is received. */
1.212 markus 190: static volatile sig_atomic_t received_sighup = 0;
191: static volatile sig_atomic_t received_sigterm = 0;
1.1 deraadt 192:
1.96 markus 193: /* session identifier, used by RSA-auth */
1.140 markus 194: u_char session_id[16];
1.96 markus 195:
1.108 markus 196: /* same for ssh2 */
1.140 markus 197: u_char *session_id2 = NULL;
1.269 markus 198: u_int session_id2_len = 0;
1.108 markus 199:
1.125 markus 200: /* record remote hostname or ip */
1.140 markus 201: u_int utmp_len = MAXHOSTNAMELEN;
1.125 markus 202:
1.211 markus 203: /* options.max_startup sized array of fd ints */
204: int *startup_pipes = NULL;
205: int startup_pipe; /* in child */
206:
1.231 provos 207: /* variables used for privilege separation */
1.263 markus 208: int use_privsep;
1.285 dtucker 209: struct monitor *pmonitor = NULL;
1.231 provos 210:
1.278 markus 211: /* global authentication context */
212: Authctxt *the_authctxt = NULL;
213:
1.299 dtucker 214: /* message to be displayed after login */
215: Buffer loginmsg;
216:
1.1 deraadt 217: /* Prototypes for various functions defined later in this file. */
1.200 itojun 218: void destroy_sensitive_data(void);
1.231 provos 219: void demote_sensitive_data(void);
1.87 markus 220:
1.200 itojun 221: static void do_ssh1_kex(void);
222: static void do_ssh2_kex(void);
1.129 provos 223:
1.87 markus 224: /*
1.75 markus 225: * Close all listening sockets
226: */
1.200 itojun 227: static void
1.75 markus 228: close_listen_socks(void)
229: {
230: int i;
1.250 deraadt 231:
1.75 markus 232: for (i = 0; i < num_listen_socks; i++)
233: close(listen_socks[i]);
234: num_listen_socks = -1;
235: }
236:
1.211 markus 237: static void
238: close_startup_pipes(void)
239: {
240: int i;
1.250 deraadt 241:
1.211 markus 242: if (startup_pipes)
243: for (i = 0; i < options.max_startups; i++)
244: if (startup_pipes[i] != -1)
245: close(startup_pipes[i]);
246: }
247:
1.75 markus 248: /*
1.65 deraadt 249: * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
250: * the effect is to reread the configuration file (and to regenerate
251: * the server key).
252: */
1.327 deraadt 253:
254: /*ARGSUSED*/
1.200 itojun 255: static void
1.64 markus 256: sighup_handler(int sig)
1.1 deraadt 257: {
1.210 deraadt 258: int save_errno = errno;
259:
1.64 markus 260: received_sighup = 1;
261: signal(SIGHUP, sighup_handler);
1.210 deraadt 262: errno = save_errno;
1.1 deraadt 263: }
264:
1.65 deraadt 265: /*
266: * Called from the main program after receiving SIGHUP.
267: * Restarts the server.
268: */
1.200 itojun 269: static void
1.165 itojun 270: sighup_restart(void)
1.1 deraadt 271: {
1.264 itojun 272: logit("Received SIGHUP; restarting.");
1.75 markus 273: close_listen_socks();
1.211 markus 274: close_startup_pipes();
1.64 markus 275: execv(saved_argv[0], saved_argv);
1.264 itojun 276: logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
1.250 deraadt 277: strerror(errno));
1.64 markus 278: exit(1);
1.1 deraadt 279: }
280:
1.65 deraadt 281: /*
282: * Generic signal handler for terminating signals in the master daemon.
283: */
1.327 deraadt 284: /*ARGSUSED*/
1.200 itojun 285: static void
1.64 markus 286: sigterm_handler(int sig)
1.1 deraadt 287: {
1.199 markus 288: received_sigterm = sig;
1.1 deraadt 289: }
290:
1.65 deraadt 291: /*
292: * SIGCHLD handler. This is called whenever a child dies. This will then
1.199 markus 293: * reap any zombies left by exited children.
1.65 deraadt 294: */
1.327 deraadt 295: /*ARGSUSED*/
1.200 itojun 296: static void
1.64 markus 297: main_sigchld_handler(int sig)
1.1 deraadt 298: {
1.250 deraadt 299: int save_errno = errno;
1.239 markus 300: pid_t pid;
1.64 markus 301: int status;
1.60 deraadt 302:
1.239 markus 303: while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
304: (pid < 0 && errno == EINTR))
1.64 markus 305: ;
1.60 deraadt 306:
1.64 markus 307: signal(SIGCHLD, main_sigchld_handler);
308: errno = save_errno;
1.1 deraadt 309: }
310:
1.65 deraadt 311: /*
312: * Signal handler for the alarm after the login grace period has expired.
313: */
1.327 deraadt 314: /*ARGSUSED*/
1.200 itojun 315: static void
1.64 markus 316: grace_alarm_handler(int sig)
1.1 deraadt 317: {
1.199 markus 318: /* XXX no idea how fix this signal handler */
319:
1.285 dtucker 320: if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
321: kill(pmonitor->m_pid, SIGALRM);
322:
1.64 markus 323: /* Log error and exit. */
1.259 markus 324: fatal("Timeout before authentication for %s", get_remote_ipaddr());
1.62 markus 325: }
326:
1.65 deraadt 327: /*
328: * Signal handler for the key regeneration alarm. Note that this
329: * alarm only occurs in the daemon waiting for connections, and it does not
330: * do anything with the private key or random state before forking.
331: * Thus there should be no concurrency control/asynchronous execution
332: * problems.
333: */
1.200 itojun 334: static void
1.174 deraadt 335: generate_ephemeral_server_key(void)
1.134 markus 336: {
1.254 deraadt 337: u_int32_t rnd = 0;
1.169 markus 338: int i;
339:
1.191 markus 340: verbose("Generating %s%d bit RSA key.",
1.185 djm 341: sensitive_data.server_key ? "new " : "", options.server_key_bits);
1.134 markus 342: if (sensitive_data.server_key != NULL)
343: key_free(sensitive_data.server_key);
1.191 markus 344: sensitive_data.server_key = key_generate(KEY_RSA1,
1.185 djm 345: options.server_key_bits);
346: verbose("RSA key generation complete.");
1.169 markus 347:
348: for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
349: if (i % 4 == 0)
1.254 deraadt 350: rnd = arc4random();
351: sensitive_data.ssh1_cookie[i] = rnd & 0xff;
352: rnd >>= 8;
1.169 markus 353: }
1.134 markus 354: arc4random_stir();
355: }
1.147 deraadt 356:
1.327 deraadt 357: /*ARGSUSED*/
1.200 itojun 358: static void
1.64 markus 359: key_regeneration_alarm(int sig)
1.1 deraadt 360: {
1.64 markus 361: int save_errno = errno;
1.250 deraadt 362:
1.151 markus 363: signal(SIGALRM, SIG_DFL);
1.64 markus 364: errno = save_errno;
1.151 markus 365: key_do_regen = 1;
1.98 markus 366: }
367:
1.200 itojun 368: static void
1.96 markus 369: sshd_exchange_identification(int sock_in, int sock_out)
370: {
1.311 djm 371: u_int i;
372: int mismatch;
1.96 markus 373: int remote_major, remote_minor;
1.102 markus 374: int major, minor;
1.96 markus 375: char *s;
376: char buf[256]; /* Must not be larger than remote_version. */
377: char remote_version[256]; /* Must be at least as big as buf. */
378:
1.103 markus 379: if ((options.protocol & SSH_PROTO_1) &&
380: (options.protocol & SSH_PROTO_2)) {
1.102 markus 381: major = PROTOCOL_MAJOR_1;
382: minor = 99;
383: } else if (options.protocol & SSH_PROTO_2) {
384: major = PROTOCOL_MAJOR_2;
385: minor = PROTOCOL_MINOR_2;
386: } else {
387: major = PROTOCOL_MAJOR_1;
388: minor = PROTOCOL_MINOR_1;
389: }
390: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
1.96 markus 391: server_version_string = xstrdup(buf);
392:
1.272 markus 393: /* Send our protocol version identification. */
394: if (atomicio(vwrite, sock_out, server_version_string,
395: strlen(server_version_string))
396: != strlen(server_version_string)) {
397: logit("Could not write ident string to %s", get_remote_ipaddr());
1.278 markus 398: cleanup_exit(255);
1.272 markus 399: }
400:
401: /* Read other sides version identification. */
402: memset(buf, 0, sizeof(buf));
403: for (i = 0; i < sizeof(buf) - 1; i++) {
404: if (atomicio(read, sock_in, &buf[i], 1) != 1) {
405: logit("Did not receive identification string from %s",
406: get_remote_ipaddr());
1.278 markus 407: cleanup_exit(255);
1.96 markus 408: }
1.272 markus 409: if (buf[i] == '\r') {
410: buf[i] = 0;
411: /* Kludge for F-Secure Macintosh < 1.0.2 */
412: if (i == 12 &&
413: strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
1.96 markus 414: break;
1.272 markus 415: continue;
416: }
417: if (buf[i] == '\n') {
418: buf[i] = 0;
419: break;
1.96 markus 420: }
421: }
1.272 markus 422: buf[sizeof(buf) - 1] = 0;
423: client_version_string = xstrdup(buf);
1.96 markus 424:
425: /*
426: * Check that the versions match. In future this might accept
427: * several versions and set appropriate flags to handle them.
428: */
429: if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
430: &remote_major, &remote_minor, remote_version) != 3) {
1.105 markus 431: s = "Protocol mismatch.\n";
1.271 deraadt 432: (void) atomicio(vwrite, sock_out, s, strlen(s));
1.96 markus 433: close(sock_in);
434: close(sock_out);
1.264 itojun 435: logit("Bad protocol version identification '%.100s' from %s",
1.96 markus 436: client_version_string, get_remote_ipaddr());
1.278 markus 437: cleanup_exit(255);
1.96 markus 438: }
439: debug("Client protocol version %d.%d; client software version %.100s",
1.217 deraadt 440: remote_major, remote_minor, remote_version);
1.96 markus 441:
1.98 markus 442: compat_datafellows(remote_version);
1.260 mickey 443:
444: if (datafellows & SSH_BUG_PROBE) {
1.264 itojun 445: logit("probed from %s with %s. Don't panic.",
1.260 mickey 446: get_remote_ipaddr(), client_version_string);
1.278 markus 447: cleanup_exit(255);
1.260 mickey 448: }
1.175 deraadt 449:
450: if (datafellows & SSH_BUG_SCANNER) {
1.264 itojun 451: logit("scanned from %s with %s. Don't panic.",
1.175 deraadt 452: get_remote_ipaddr(), client_version_string);
1.278 markus 453: cleanup_exit(255);
1.175 deraadt 454: }
1.98 markus 455:
1.102 markus 456: mismatch = 0;
1.214 deraadt 457: switch (remote_major) {
1.96 markus 458: case 1:
1.108 markus 459: if (remote_minor == 99) {
460: if (options.protocol & SSH_PROTO_2)
461: enable_compat20();
462: else
463: mismatch = 1;
464: break;
465: }
1.102 markus 466: if (!(options.protocol & SSH_PROTO_1)) {
467: mismatch = 1;
468: break;
469: }
1.96 markus 470: if (remote_minor < 3) {
1.121 provos 471: packet_disconnect("Your ssh version is too old and "
1.96 markus 472: "is no longer supported. Please install a newer version.");
473: } else if (remote_minor == 3) {
474: /* note that this disables agent-forwarding */
475: enable_compat13();
476: }
1.102 markus 477: break;
1.98 markus 478: case 2:
1.102 markus 479: if (options.protocol & SSH_PROTO_2) {
1.98 markus 480: enable_compat20();
481: break;
482: }
1.99 markus 483: /* FALLTHROUGH */
1.105 markus 484: default:
1.102 markus 485: mismatch = 1;
486: break;
487: }
488: chop(server_version_string);
489: debug("Local version string %.200s", server_version_string);
490:
491: if (mismatch) {
1.96 markus 492: s = "Protocol major versions differ.\n";
1.271 deraadt 493: (void) atomicio(vwrite, sock_out, s, strlen(s));
1.96 markus 494: close(sock_in);
495: close(sock_out);
1.264 itojun 496: logit("Protocol major versions differ for %s: %.200s vs. %.200s",
1.102 markus 497: get_remote_ipaddr(),
498: server_version_string, client_version_string);
1.278 markus 499: cleanup_exit(255);
1.96 markus 500: }
1.108 markus 501: }
502:
1.134 markus 503: /* Destroy the host and server keys. They will no longer be needed. */
1.108 markus 504: void
505: destroy_sensitive_data(void)
506: {
1.134 markus 507: int i;
508:
509: if (sensitive_data.server_key) {
510: key_free(sensitive_data.server_key);
511: sensitive_data.server_key = NULL;
512: }
1.217 deraadt 513: for (i = 0; i < options.num_host_key_files; i++) {
1.134 markus 514: if (sensitive_data.host_keys[i]) {
515: key_free(sensitive_data.host_keys[i]);
516: sensitive_data.host_keys[i] = NULL;
517: }
518: }
519: sensitive_data.ssh1_host_key = NULL;
1.169 markus 520: memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
1.134 markus 521: }
522:
1.231 provos 523: /* Demote private to public keys for network child */
524: void
525: demote_sensitive_data(void)
526: {
527: Key *tmp;
528: int i;
529:
530: if (sensitive_data.server_key) {
531: tmp = key_demote(sensitive_data.server_key);
532: key_free(sensitive_data.server_key);
533: sensitive_data.server_key = tmp;
534: }
535:
536: for (i = 0; i < options.num_host_key_files; i++) {
537: if (sensitive_data.host_keys[i]) {
538: tmp = key_demote(sensitive_data.host_keys[i]);
539: key_free(sensitive_data.host_keys[i]);
540: sensitive_data.host_keys[i] = tmp;
541: if (tmp->type == KEY_RSA1)
542: sensitive_data.ssh1_host_key = tmp;
543: }
544: }
545:
546: /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
547: }
548:
1.233 markus 549: static void
1.231 provos 550: privsep_preauth_child(void)
551: {
1.254 deraadt 552: u_int32_t rnd[256];
1.253 deraadt 553: gid_t gidset[1];
1.250 deraadt 554: struct passwd *pw;
1.231 provos 555: int i;
556:
557: /* Enable challenge-response authentication for privilege separation */
558: privsep_challenge_enable();
559:
560: for (i = 0; i < 256; i++)
1.254 deraadt 561: rnd[i] = arc4random();
562: RAND_seed(rnd, sizeof(rnd));
1.231 provos 563:
564: /* Demote the private keys to public keys. */
565: demote_sensitive_data();
566:
1.235 stevesk 567: if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1.240 djm 568: fatal("Privilege separation user %s does not exist",
569: SSH_PRIVSEP_USER);
1.235 stevesk 570: memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
571: endpwent();
572:
1.255 deraadt 573: /* Change our root directory */
1.232 stevesk 574: if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
575: fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
576: strerror(errno));
1.231 provos 577: if (chdir("/") == -1)
1.236 stevesk 578: fatal("chdir(\"/\"): %s", strerror(errno));
1.234 markus 579:
1.231 provos 580: /* Drop our privileges */
1.235 stevesk 581: debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
582: (u_int)pw->pw_gid);
1.251 markus 583: #if 0
1.287 djm 584: /* XXX not ready, too heavy after chroot */
1.235 stevesk 585: do_setusercontext(pw);
1.251 markus 586: #else
587: gidset[0] = pw->pw_gid;
588: if (setgroups(1, gidset) < 0)
589: fatal("setgroups: %.100s", strerror(errno));
590: permanently_set_uid(pw);
591: #endif
1.231 provos 592: }
593:
1.278 markus 594: static int
595: privsep_preauth(Authctxt *authctxt)
1.237 markus 596: {
597: int status;
598: pid_t pid;
599:
600: /* Set up unprivileged child process to deal with network data */
1.242 mouring 601: pmonitor = monitor_init();
1.237 markus 602: /* Store a pointer to the kex for later rekeying */
1.242 mouring 603: pmonitor->m_pkex = &xxx_kex;
1.237 markus 604:
605: pid = fork();
606: if (pid == -1) {
607: fatal("fork of unprivileged child failed");
608: } else if (pid != 0) {
1.245 mpech 609: debug2("Network child is on pid %ld", (long)pid);
1.237 markus 610:
1.242 mouring 611: close(pmonitor->m_recvfd);
1.285 dtucker 612: pmonitor->m_pid = pid;
1.278 markus 613: monitor_child_preauth(authctxt, pmonitor);
1.242 mouring 614: close(pmonitor->m_sendfd);
1.237 markus 615:
616: /* Sync memory */
1.242 mouring 617: monitor_sync(pmonitor);
1.237 markus 618:
619: /* Wait for the child's exit status */
1.239 markus 620: while (waitpid(pid, &status, 0) < 0)
621: if (errno != EINTR)
622: break;
1.278 markus 623: return (1);
1.237 markus 624: } else {
625: /* child */
626:
1.242 mouring 627: close(pmonitor->m_sendfd);
1.237 markus 628:
629: /* Demote the child */
630: if (getuid() == 0 || geteuid() == 0)
631: privsep_preauth_child();
1.238 stevesk 632: setproctitle("%s", "[net]");
1.237 markus 633: }
1.278 markus 634: return (0);
1.237 markus 635: }
636:
1.233 markus 637: static void
1.237 markus 638: privsep_postauth(Authctxt *authctxt)
1.231 provos 639: {
640: if (authctxt->pw->pw_uid == 0 || options.use_login) {
641: /* File descriptor passing is broken or root login */
642: use_privsep = 0;
1.315 djm 643: goto skip;
1.231 provos 644: }
1.234 markus 645:
1.231 provos 646: /* New socket pair */
1.242 mouring 647: monitor_reinit(pmonitor);
1.231 provos 648:
1.242 mouring 649: pmonitor->m_pid = fork();
650: if (pmonitor->m_pid == -1)
1.231 provos 651: fatal("fork of unprivileged child failed");
1.242 mouring 652: else if (pmonitor->m_pid != 0) {
1.245 mpech 653: debug2("User child is on pid %ld", (long)pmonitor->m_pid);
1.242 mouring 654: close(pmonitor->m_recvfd);
1.307 otto 655: buffer_clear(&loginmsg);
1.242 mouring 656: monitor_child_postauth(pmonitor);
1.231 provos 657:
658: /* NEVERREACHED */
659: exit(0);
660: }
661:
1.242 mouring 662: close(pmonitor->m_sendfd);
1.231 provos 663:
664: /* Demote the private keys to public keys. */
665: demote_sensitive_data();
666:
667: /* Drop privileges */
668: do_setusercontext(authctxt->pw);
669:
1.315 djm 670: skip:
1.231 provos 671: /* It is safe now to apply the key state */
1.242 mouring 672: monitor_apply_keystate(pmonitor);
1.312 markus 673:
674: /*
675: * Tell the packet layer that authentication was successful, since
676: * this information is not part of the key state.
677: */
678: packet_set_authenticated();
1.231 provos 679: }
680:
1.200 itojun 681: static char *
1.134 markus 682: list_hostkey_types(void)
683: {
1.223 markus 684: Buffer b;
1.281 jakob 685: const char *p;
686: char *ret;
1.134 markus 687: int i;
1.223 markus 688:
689: buffer_init(&b);
1.217 deraadt 690: for (i = 0; i < options.num_host_key_files; i++) {
1.134 markus 691: Key *key = sensitive_data.host_keys[i];
692: if (key == NULL)
693: continue;
1.214 deraadt 694: switch (key->type) {
1.134 markus 695: case KEY_RSA:
696: case KEY_DSA:
1.223 markus 697: if (buffer_len(&b) > 0)
698: buffer_append(&b, ",", 1);
699: p = key_ssh_name(key);
700: buffer_append(&b, p, strlen(p));
1.134 markus 701: break;
702: }
703: }
1.223 markus 704: buffer_append(&b, "\0", 1);
1.281 jakob 705: ret = xstrdup(buffer_ptr(&b));
1.223 markus 706: buffer_free(&b);
1.281 jakob 707: debug("list_hostkey_types: %s", ret);
708: return ret;
1.134 markus 709: }
710:
1.231 provos 711: Key *
1.134 markus 712: get_hostkey_by_type(int type)
713: {
714: int i;
1.250 deraadt 715:
1.217 deraadt 716: for (i = 0; i < options.num_host_key_files; i++) {
1.134 markus 717: Key *key = sensitive_data.host_keys[i];
718: if (key != NULL && key->type == type)
719: return key;
720: }
721: return NULL;
1.96 markus 722: }
723:
1.231 provos 724: Key *
725: get_hostkey_by_index(int ind)
726: {
727: if (ind < 0 || ind >= options.num_host_key_files)
728: return (NULL);
729: return (sensitive_data.host_keys[ind]);
730: }
731:
732: int
733: get_hostkey_index(Key *key)
734: {
735: int i;
1.250 deraadt 736:
1.231 provos 737: for (i = 0; i < options.num_host_key_files; i++) {
738: if (key == sensitive_data.host_keys[i])
739: return (i);
740: }
741: return (-1);
742: }
743:
1.124 markus 744: /*
745: * returns 1 if connection should be dropped, 0 otherwise.
746: * dropping starts at connection #max_startups_begin with a probability
747: * of (max_startups_rate/100). the probability increases linearly until
748: * all connections are dropped for startups > max_startups
749: */
1.200 itojun 750: static int
1.124 markus 751: drop_connection(int startups)
752: {
1.303 mickey 753: int p, r;
1.124 markus 754:
755: if (startups < options.max_startups_begin)
756: return 0;
757: if (startups >= options.max_startups)
758: return 1;
759: if (options.max_startups_rate == 100)
760: return 1;
761:
762: p = 100 - options.max_startups_rate;
763: p *= startups - options.max_startups_begin;
1.303 mickey 764: p /= options.max_startups - options.max_startups_begin;
1.124 markus 765: p += options.max_startups_rate;
1.303 mickey 766: r = arc4random() % 100;
1.124 markus 767:
1.304 djm 768: debug("drop_connection: p %d, r %d", p, r);
1.124 markus 769: return (r < p) ? 1 : 0;
770: }
771:
1.215 markus 772: static void
773: usage(void)
774: {
1.290 markus 775: fprintf(stderr, "%s, %s\n",
1.280 markus 776: SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
1.289 markus 777: fprintf(stderr,
778: "usage: sshd [-46Ddeiqt] [-b bits] [-f config_file] [-g login_grace_time]\n"
779: " [-h host_key_file] [-k key_gen_time] [-o option] [-p port] [-u len]\n"
780: );
1.215 markus 781: exit(1);
782: }
783:
1.294 djm 784: static void
785: send_rexec_state(int fd, Buffer *conf)
786: {
787: Buffer m;
788:
789: debug3("%s: entering fd = %d config len %d", __func__, fd,
790: buffer_len(conf));
791:
792: /*
793: * Protocol from reexec master to child:
794: * string configuration
795: * u_int ephemeral_key_follows
796: * bignum e (only if ephemeral_key_follows == 1)
797: * bignum n "
798: * bignum d "
799: * bignum iqmp "
800: * bignum p "
801: * bignum q "
802: */
803: buffer_init(&m);
804: buffer_put_cstring(&m, buffer_ptr(conf));
805:
1.298 deraadt 806: if (sensitive_data.server_key != NULL &&
1.294 djm 807: sensitive_data.server_key->type == KEY_RSA1) {
808: buffer_put_int(&m, 1);
809: buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
810: buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
811: buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
812: buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
813: buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
814: buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
815: } else
816: buffer_put_int(&m, 0);
817:
818: if (ssh_msg_send(fd, 0, &m) == -1)
819: fatal("%s: ssh_msg_send failed", __func__);
820:
821: buffer_free(&m);
822:
823: debug3("%s: done", __func__);
824: }
825:
826: static void
827: recv_rexec_state(int fd, Buffer *conf)
828: {
829: Buffer m;
830: char *cp;
831: u_int len;
832:
833: debug3("%s: entering fd = %d", __func__, fd);
834:
835: buffer_init(&m);
836:
837: if (ssh_msg_recv(fd, &m) == -1)
838: fatal("%s: ssh_msg_recv failed", __func__);
839: if (buffer_get_char(&m) != 0)
840: fatal("%s: rexec version mismatch", __func__);
841:
842: cp = buffer_get_string(&m, &len);
843: if (conf != NULL)
844: buffer_append(conf, cp, len + 1);
845: xfree(cp);
846:
847: if (buffer_get_int(&m)) {
848: if (sensitive_data.server_key != NULL)
849: key_free(sensitive_data.server_key);
850: sensitive_data.server_key = key_new_private(KEY_RSA1);
851: buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
852: buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
853: buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
854: buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
855: buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
856: buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
857: rsa_generate_additional_parameters(
858: sensitive_data.server_key->rsa);
859: }
860: buffer_free(&m);
861:
862: debug3("%s: done", __func__);
863: }
864:
1.65 deraadt 865: /*
866: * Main program for the daemon.
867: */
1.2 provos 868: int
869: main(int ac, char **av)
1.1 deraadt 870: {
1.64 markus 871: extern char *optarg;
872: extern int optind;
1.329 djm 873: int opt, j, i, on = 1;
1.297 avsm 874: int sock_in = -1, sock_out = -1, newsock = -1;
1.107 deraadt 875: pid_t pid;
1.75 markus 876: socklen_t fromlen;
877: fd_set *fdset;
878: struct sockaddr_storage from;
1.64 markus 879: const char *remote_ip;
880: int remote_port;
881: FILE *f;
1.75 markus 882: struct addrinfo *ai;
883: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.283 markus 884: char *line;
1.75 markus 885: int listen_sock, maxfd;
1.302 djm 886: int startup_p[2] = { -1 , -1 }, config_s[2] = { -1 , -1 };
1.120 markus 887: int startups = 0;
1.278 markus 888: Key *key;
1.230 provos 889: Authctxt *authctxt;
1.151 markus 890: int ret, key_used = 0;
1.294 djm 891: Buffer cfg;
1.64 markus 892:
1.138 markus 893: /* Save argv. */
1.64 markus 894: saved_argv = av;
1.294 djm 895: rexec_argc = ac;
1.313 djm 896:
897: /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
898: sanitise_stdfd();
1.64 markus 899:
900: /* Initialize configuration options to their default values. */
901: initialize_server_options(&options);
902:
903: /* Parse command-line arguments. */
1.294 djm 904: while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:dDeiqrtQR46")) != -1) {
1.64 markus 905: switch (opt) {
1.75 markus 906: case '4':
1.305 djm 907: options.address_family = AF_INET;
1.75 markus 908: break;
909: case '6':
1.305 djm 910: options.address_family = AF_INET6;
1.75 markus 911: break;
1.64 markus 912: case 'f':
913: config_file_name = optarg;
914: break;
915: case 'd':
1.273 markus 916: if (debug_flag == 0) {
1.127 markus 917: debug_flag = 1;
918: options.log_level = SYSLOG_LEVEL_DEBUG1;
1.273 markus 919: } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1.127 markus 920: options.log_level++;
1.64 markus 921: break;
1.135 markus 922: case 'D':
923: no_daemon_flag = 1;
1.192 lebel 924: break;
925: case 'e':
926: log_stderr = 1;
1.135 markus 927: break;
1.64 markus 928: case 'i':
929: inetd_flag = 1;
930: break;
1.294 djm 931: case 'r':
932: rexec_flag = 0;
933: break;
934: case 'R':
935: rexeced_flag = 1;
936: inetd_flag = 1;
937: break;
1.64 markus 938: case 'Q':
1.158 markus 939: /* ignored */
1.64 markus 940: break;
941: case 'q':
942: options.log_level = SYSLOG_LEVEL_QUIET;
943: break;
944: case 'b':
1.327 deraadt 945: options.server_key_bits = (int)strtonum(optarg, 256,
946: 32768, NULL);
1.64 markus 947: break;
948: case 'p':
1.75 markus 949: options.ports_from_cmdline = 1;
1.127 markus 950: if (options.num_ports >= MAX_PORTS) {
951: fprintf(stderr, "too many ports.\n");
952: exit(1);
953: }
1.193 stevesk 954: options.ports[options.num_ports++] = a2port(optarg);
955: if (options.ports[options.num_ports-1] == 0) {
956: fprintf(stderr, "Bad port number.\n");
957: exit(1);
958: }
1.64 markus 959: break;
960: case 'g':
1.197 stevesk 961: if ((options.login_grace_time = convtime(optarg)) == -1) {
962: fprintf(stderr, "Invalid login grace time.\n");
963: exit(1);
964: }
1.64 markus 965: break;
966: case 'k':
1.197 stevesk 967: if ((options.key_regeneration_time = convtime(optarg)) == -1) {
968: fprintf(stderr, "Invalid key regeneration interval.\n");
969: exit(1);
970: }
1.64 markus 971: break;
972: case 'h':
1.134 markus 973: if (options.num_host_key_files >= MAX_HOSTKEYS) {
974: fprintf(stderr, "too many host keys.\n");
975: exit(1);
976: }
977: options.host_key_files[options.num_host_key_files++] = optarg;
1.64 markus 978: break;
1.203 stevesk 979: case 't':
980: test_flag = 1;
981: break;
1.125 markus 982: case 'u':
1.327 deraadt 983: utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1.257 stevesk 984: if (utmp_len > MAXHOSTNAMELEN) {
985: fprintf(stderr, "Invalid utmp length.\n");
986: exit(1);
987: }
1.125 markus 988: break;
1.215 markus 989: case 'o':
1.283 markus 990: line = xstrdup(optarg);
991: if (process_server_config_line(&options, line,
1.215 markus 992: "command-line", 0) != 0)
1.217 deraadt 993: exit(1);
1.283 markus 994: xfree(line);
1.215 markus 995: break;
1.64 markus 996: case '?':
997: default:
1.215 markus 998: usage();
999: break;
1.64 markus 1000: }
1001: }
1.294 djm 1002: if (rexeced_flag || inetd_flag)
1003: rexec_flag = 0;
1004: if (rexec_flag && (av[0] == NULL || *av[0] != '/'))
1005: fatal("sshd re-exec requires execution with an absolute path");
1006: if (rexeced_flag)
1.296 djm 1007: closefrom(REEXEC_MIN_FREE_FD);
1008: else
1009: closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1.294 djm 1010:
1.180 markus 1011: SSLeay_add_all_algorithms();
1.64 markus 1012:
1.75 markus 1013: /*
1014: * Force logging to stderr until we have loaded the private host
1015: * key (unless started from inetd)
1016: */
1.138 markus 1017: log_init(__progname,
1.224 markus 1018: options.log_level == SYSLOG_LEVEL_NOT_SET ?
1019: SYSLOG_LEVEL_INFO : options.log_level,
1020: options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1021: SYSLOG_FACILITY_AUTH : options.log_facility,
1.261 markus 1022: log_stderr || !inetd_flag);
1.75 markus 1023:
1.294 djm 1024: sensitive_data.server_key = NULL;
1025: sensitive_data.ssh1_host_key = NULL;
1026: sensitive_data.have_ssh1_key = 0;
1027: sensitive_data.have_ssh2_key = 0;
1028:
1029: /* Fetch our configuration */
1030: buffer_init(&cfg);
1031: if (rexeced_flag)
1.296 djm 1032: recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1.294 djm 1033: else
1034: load_server_config(config_file_name, &cfg);
1035:
1036: parse_server_config(&options,
1037: rexeced_flag ? "rexec" : config_file_name, &cfg);
1038:
1039: if (!rexec_flag)
1040: buffer_free(&cfg);
1.64 markus 1041:
1042: /* Fill in default values for those options not explicitly set. */
1043: fill_default_server_options(&options);
1.305 djm 1044:
1045: /* set default channel AF */
1046: channel_set_af(options.address_family);
1.64 markus 1047:
1048: /* Check that there are no remaining arguments. */
1049: if (optind < ac) {
1050: fprintf(stderr, "Extra argument %s.\n", av[optind]);
1051: exit(1);
1052: }
1053:
1054: debug("sshd version %.100s", SSH_VERSION);
1055:
1.134 markus 1056: /* load private host keys */
1.329 djm 1057: sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1.255 deraadt 1058: sizeof(Key *));
1.217 deraadt 1059: for (i = 0; i < options.num_host_key_files; i++)
1.141 markus 1060: sensitive_data.host_keys[i] = NULL;
1.134 markus 1061:
1.217 deraadt 1062: for (i = 0; i < options.num_host_key_files; i++) {
1.179 markus 1063: key = key_load_private(options.host_key_files[i], "", NULL);
1064: sensitive_data.host_keys[i] = key;
1.134 markus 1065: if (key == NULL) {
1.195 markus 1066: error("Could not load host key: %s",
1067: options.host_key_files[i]);
1.179 markus 1068: sensitive_data.host_keys[i] = NULL;
1.134 markus 1069: continue;
1070: }
1.214 deraadt 1071: switch (key->type) {
1.134 markus 1072: case KEY_RSA1:
1073: sensitive_data.ssh1_host_key = key;
1074: sensitive_data.have_ssh1_key = 1;
1075: break;
1076: case KEY_RSA:
1077: case KEY_DSA:
1078: sensitive_data.have_ssh2_key = 1;
1079: break;
1080: }
1.179 markus 1081: debug("private host key: #%d type %d %s", i, key->type,
1082: key_type(key));
1.134 markus 1083: }
1084: if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1.264 itojun 1085: logit("Disabling protocol version 1. Could not load host key");
1.108 markus 1086: options.protocol &= ~SSH_PROTO_1;
1087: }
1.134 markus 1088: if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1.264 itojun 1089: logit("Disabling protocol version 2. Could not load host key");
1.134 markus 1090: options.protocol &= ~SSH_PROTO_2;
1.108 markus 1091: }
1.162 stevesk 1092: if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1.264 itojun 1093: logit("sshd: no hostkeys available -- exiting.");
1.64 markus 1094: exit(1);
1095: }
1096:
1.108 markus 1097: /* Check certain values for sanity. */
1098: if (options.protocol & SSH_PROTO_1) {
1099: if (options.server_key_bits < 512 ||
1100: options.server_key_bits > 32768) {
1101: fprintf(stderr, "Bad server key size.\n");
1102: exit(1);
1103: }
1104: /*
1105: * Check that server and host key lengths differ sufficiently. This
1106: * is necessary to make double encryption work with rsaref. Oh, I
1107: * hate software patents. I dont know if this can go? Niels
1108: */
1109: if (options.server_key_bits >
1.250 deraadt 1110: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1111: SSH_KEY_BITS_RESERVED && options.server_key_bits <
1112: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1113: SSH_KEY_BITS_RESERVED) {
1.108 markus 1114: options.server_key_bits =
1.250 deraadt 1115: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1116: SSH_KEY_BITS_RESERVED;
1.108 markus 1117: debug("Forcing server key to %d bits to make it differ from host key.",
1118: options.server_key_bits);
1119: }
1.244 markus 1120: }
1121:
1122: if (use_privsep) {
1123: struct stat st;
1124:
1.327 deraadt 1125: if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1.244 markus 1126: fatal("Privilege separation user %s does not exist",
1127: SSH_PRIVSEP_USER);
1128: if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1129: (S_ISDIR(st.st_mode) == 0))
1130: fatal("Missing privilege separation directory: %s",
1.247 stevesk 1131: _PATH_PRIVSEP_CHROOT_DIR);
1132: if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1.262 markus 1133: fatal("%s must be owned by root and not group or "
1134: "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1.108 markus 1135: }
1.203 stevesk 1136:
1137: /* Configuration looks good, so exit if in test mode. */
1138: if (test_flag)
1139: exit(0);
1.108 markus 1140:
1.294 djm 1141: if (rexec_flag) {
1.329 djm 1142: rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1.294 djm 1143: for (i = 0; i < rexec_argc; i++) {
1144: debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1145: rexec_argv[i] = saved_argv[i];
1146: }
1147: rexec_argv[rexec_argc] = "-R";
1148: rexec_argv[rexec_argc + 1] = NULL;
1149: }
1150:
1.108 markus 1151: /* Initialize the log (it is reinitialized below in case we forked). */
1.306 dtucker 1152: if (debug_flag && (!inetd_flag || rexeced_flag))
1.64 markus 1153: log_stderr = 1;
1.138 markus 1154: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.64 markus 1155:
1.108 markus 1156: /*
1157: * If not in debugging mode, and not started from inetd, disconnect
1158: * from the controlling terminal, and fork. The original process
1159: * exits.
1160: */
1.135 markus 1161: if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1.1 deraadt 1162: #ifdef TIOCNOTTY
1.64 markus 1163: int fd;
1.1 deraadt 1164: #endif /* TIOCNOTTY */
1.64 markus 1165: if (daemon(0, 0) < 0)
1166: fatal("daemon() failed: %.200s", strerror(errno));
1167:
1168: /* Disconnect from the controlling tty. */
1.1 deraadt 1169: #ifdef TIOCNOTTY
1.165 itojun 1170: fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1.64 markus 1171: if (fd >= 0) {
1172: (void) ioctl(fd, TIOCNOTTY, NULL);
1173: close(fd);
1174: }
1175: #endif /* TIOCNOTTY */
1176: }
1177: /* Reinitialize the log (because of the fork above). */
1.138 markus 1178: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.64 markus 1179:
1180: /* Initialize the random number generator. */
1181: arc4random_stir();
1182:
1183: /* Chdir to the root directory so that the current disk can be
1184: unmounted if desired. */
1185: chdir("/");
1.217 deraadt 1186:
1.178 markus 1187: /* ignore SIGPIPE */
1188: signal(SIGPIPE, SIG_IGN);
1.64 markus 1189:
1190: /* Start listening for a socket, unless started from inetd. */
1191: if (inetd_flag) {
1.294 djm 1192: int fd;
1193:
1.123 djm 1194: startup_pipe = -1;
1.294 djm 1195: if (rexeced_flag) {
1.296 djm 1196: close(REEXEC_CONFIG_PASS_FD);
1.294 djm 1197: sock_in = sock_out = dup(STDIN_FILENO);
1198: if (!debug_flag) {
1.296 djm 1199: startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
1200: close(REEXEC_STARTUP_PIPE_FD);
1.294 djm 1201: }
1202: } else {
1203: sock_in = dup(STDIN_FILENO);
1204: sock_out = dup(STDOUT_FILENO);
1205: }
1.108 markus 1206: /*
1207: * We intentionally do not close the descriptors 0, 1, and 2
1.294 djm 1208: * as our code for setting the descriptors won't work if
1.108 markus 1209: * ttyfd happens to be one of those.
1210: */
1.294 djm 1211: if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1212: dup2(fd, STDIN_FILENO);
1213: dup2(fd, STDOUT_FILENO);
1214: if (fd > STDOUT_FILENO)
1215: close(fd);
1216: }
1.64 markus 1217: debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1.294 djm 1218: if ((options.protocol & SSH_PROTO_1) &&
1219: sensitive_data.server_key == NULL)
1.174 deraadt 1220: generate_ephemeral_server_key();
1.64 markus 1221: } else {
1.75 markus 1222: for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
1223: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
1224: continue;
1225: if (num_listen_socks >= MAX_LISTEN_SOCKS)
1226: fatal("Too many listen sockets. "
1227: "Enlarge MAX_LISTEN_SOCKS");
1.308 dtucker 1228: if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
1.75 markus 1229: ntop, sizeof(ntop), strport, sizeof(strport),
1.308 dtucker 1230: NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
1231: error("getnameinfo failed: %.100s",
1232: (ret != EAI_SYSTEM) ? gai_strerror(ret) :
1233: strerror(errno));
1.75 markus 1234: continue;
1235: }
1236: /* Create socket for listening. */
1.265 markus 1237: listen_sock = socket(ai->ai_family, ai->ai_socktype,
1238: ai->ai_protocol);
1.75 markus 1239: if (listen_sock < 0) {
1240: /* kernel may not support ipv6 */
1241: verbose("socket: %.100s", strerror(errno));
1242: continue;
1243: }
1.293 djm 1244: if (set_nonblock(listen_sock) == -1) {
1.286 markus 1245: close(listen_sock);
1246: continue;
1247: }
1.75 markus 1248: /*
1.258 stevesk 1249: * Set socket options.
1250: * Allow local port reuse in TIME_WAIT.
1.75 markus 1251: */
1.258 stevesk 1252: if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
1253: &on, sizeof(on)) == -1)
1254: error("setsockopt SO_REUSEADDR: %s", strerror(errno));
1.75 markus 1255:
1256: debug("Bind to port %s on %s.", strport, ntop);
1257:
1258: /* Bind the socket to the desired port. */
1259: if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
1260: error("Bind to port %s on %s failed: %.200s.",
1261: strport, ntop, strerror(errno));
1262: close(listen_sock);
1263: continue;
1264: }
1265: listen_socks[num_listen_socks] = listen_sock;
1266: num_listen_socks++;
1267:
1268: /* Start listening on the port. */
1.325 djm 1269: if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
1270: fatal("listen on [%s]:%s: %.100s",
1271: ntop, strport, strerror(errno));
1.264 itojun 1272: logit("Server listening on %s port %s.", ntop, strport);
1.64 markus 1273: }
1.75 markus 1274: freeaddrinfo(options.listen_addrs);
1275:
1276: if (!num_listen_socks)
1277: fatal("Cannot bind any address.");
1278:
1.201 markus 1279: if (options.protocol & SSH_PROTO_1)
1280: generate_ephemeral_server_key();
1281:
1282: /*
1283: * Arrange to restart on SIGHUP. The handler needs
1284: * listen_sock.
1285: */
1286: signal(SIGHUP, sighup_handler);
1287:
1288: signal(SIGTERM, sigterm_handler);
1289: signal(SIGQUIT, sigterm_handler);
1290:
1291: /* Arrange SIGCHLD to be caught. */
1292: signal(SIGCHLD, main_sigchld_handler);
1293:
1294: /* Write out the pid file after the sigterm handler is setup */
1.64 markus 1295: if (!debug_flag) {
1.66 markus 1296: /*
1.136 todd 1297: * Record our pid in /var/run/sshd.pid to make it
1298: * easier to kill the correct sshd. We don't want to
1299: * do this before the bind above because the bind will
1.66 markus 1300: * fail if there already is a daemon, and this will
1301: * overwrite any old pid in the file.
1302: */
1.112 markus 1303: f = fopen(options.pid_file, "w");
1.270 djm 1304: if (f == NULL) {
1305: error("Couldn't create pid file \"%s\": %s",
1306: options.pid_file, strerror(errno));
1307: } else {
1.245 mpech 1308: fprintf(f, "%ld\n", (long) getpid());
1.64 markus 1309: fclose(f);
1310: }
1311: }
1312:
1.75 markus 1313: /* setup fd set for listen */
1.120 markus 1314: fdset = NULL;
1.75 markus 1315: maxfd = 0;
1316: for (i = 0; i < num_listen_socks; i++)
1317: if (listen_socks[i] > maxfd)
1318: maxfd = listen_socks[i];
1.120 markus 1319: /* pipes connected to unauthenticated childs */
1.329 djm 1320: startup_pipes = xcalloc(options.max_startups, sizeof(int));
1.120 markus 1321: for (i = 0; i < options.max_startups; i++)
1322: startup_pipes[i] = -1;
1.75 markus 1323:
1.66 markus 1324: /*
1325: * Stay listening for connections until the system crashes or
1326: * the daemon is killed with a signal.
1327: */
1.64 markus 1328: for (;;) {
1329: if (received_sighup)
1330: sighup_restart();
1.120 markus 1331: if (fdset != NULL)
1332: xfree(fdset);
1.329 djm 1333: fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1334: sizeof(fd_mask));
1.120 markus 1335:
1.75 markus 1336: for (i = 0; i < num_listen_socks; i++)
1337: FD_SET(listen_socks[i], fdset);
1.120 markus 1338: for (i = 0; i < options.max_startups; i++)
1339: if (startup_pipes[i] != -1)
1340: FD_SET(startup_pipes[i], fdset);
1341:
1342: /* Wait in select until there is a connection. */
1.151 markus 1343: ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1344: if (ret < 0 && errno != EINTR)
1345: error("select: %.100s", strerror(errno));
1.199 markus 1346: if (received_sigterm) {
1.264 itojun 1347: logit("Received signal %d; terminating.",
1.213 itojun 1348: (int) received_sigterm);
1.199 markus 1349: close_listen_socks();
1350: unlink(options.pid_file);
1351: exit(255);
1352: }
1.151 markus 1353: if (key_used && key_do_regen) {
1.174 deraadt 1354: generate_ephemeral_server_key();
1.151 markus 1355: key_used = 0;
1356: key_do_regen = 0;
1357: }
1358: if (ret < 0)
1.75 markus 1359: continue;
1.151 markus 1360:
1.120 markus 1361: for (i = 0; i < options.max_startups; i++)
1362: if (startup_pipes[i] != -1 &&
1363: FD_ISSET(startup_pipes[i], fdset)) {
1364: /*
1365: * the read end of the pipe is ready
1366: * if the child has closed the pipe
1.143 markus 1367: * after successful authentication
1.120 markus 1368: * or if the child has died
1369: */
1370: close(startup_pipes[i]);
1371: startup_pipes[i] = -1;
1372: startups--;
1373: }
1.75 markus 1374: for (i = 0; i < num_listen_socks; i++) {
1375: if (!FD_ISSET(listen_socks[i], fdset))
1.70 provos 1376: continue;
1.120 markus 1377: fromlen = sizeof(from);
1.327 deraadt 1378: newsock = accept(listen_socks[i],
1379: (struct sockaddr *)&from, &fromlen);
1.120 markus 1380: if (newsock < 0) {
1381: if (errno != EINTR && errno != EWOULDBLOCK)
1382: error("accept: %.100s", strerror(errno));
1.286 markus 1383: continue;
1384: }
1.293 djm 1385: if (unset_nonblock(newsock) == -1) {
1.286 markus 1386: close(newsock);
1.120 markus 1387: continue;
1388: }
1.124 markus 1389: if (drop_connection(startups) == 1) {
1390: debug("drop connection #%d", startups);
1.120 markus 1391: close(newsock);
1392: continue;
1393: }
1394: if (pipe(startup_p) == -1) {
1395: close(newsock);
1396: continue;
1397: }
1398:
1.294 djm 1399: if (rexec_flag && socketpair(AF_UNIX,
1400: SOCK_STREAM, 0, config_s) == -1) {
1401: error("reexec socketpair: %s",
1402: strerror(errno));
1403: close(newsock);
1404: close(startup_p[0]);
1405: close(startup_p[1]);
1406: continue;
1407: }
1408:
1.120 markus 1409: for (j = 0; j < options.max_startups; j++)
1410: if (startup_pipes[j] == -1) {
1411: startup_pipes[j] = startup_p[0];
1412: if (maxfd < startup_p[0])
1413: maxfd = startup_p[0];
1414: startups++;
1415: break;
1416: }
1.161 stevesk 1417:
1.66 markus 1418: /*
1.120 markus 1419: * Got connection. Fork a child to handle it, unless
1420: * we are in debugging mode.
1.66 markus 1421: */
1.120 markus 1422: if (debug_flag) {
1.66 markus 1423: /*
1.120 markus 1424: * In debugging mode. Close the listening
1425: * socket, and start processing the
1426: * connection without forking.
1.66 markus 1427: */
1.120 markus 1428: debug("Server will not fork when running in debugging mode.");
1.75 markus 1429: close_listen_socks();
1.64 markus 1430: sock_in = newsock;
1431: sock_out = newsock;
1.294 djm 1432: close(startup_p[0]);
1433: close(startup_p[1]);
1.122 deraadt 1434: startup_pipe = -1;
1.120 markus 1435: pid = getpid();
1.294 djm 1436: if (rexec_flag) {
1437: send_rexec_state(config_s[0],
1438: &cfg);
1439: close(config_s[0]);
1440: }
1.64 markus 1441: break;
1.120 markus 1442: } else {
1443: /*
1444: * Normal production daemon. Fork, and have
1445: * the child process the connection. The
1446: * parent continues listening.
1447: */
1448: if ((pid = fork()) == 0) {
1449: /*
1.327 deraadt 1450: * Child. Close the listening and
1451: * max_startup sockets. Start using
1452: * the accepted socket. Reinitialize
1453: * logging (since our pid has changed).
1454: * We break out of the loop to handle
1.120 markus 1455: * the connection.
1456: */
1457: startup_pipe = startup_p[1];
1.211 markus 1458: close_startup_pipes();
1.120 markus 1459: close_listen_socks();
1460: sock_in = newsock;
1461: sock_out = newsock;
1.327 deraadt 1462: log_init(__progname,
1463: options.log_level,
1464: options.log_facility,
1465: log_stderr);
1.302 djm 1466: if (rexec_flag)
1467: close(config_s[0]);
1.120 markus 1468: break;
1469: }
1.64 markus 1470: }
1471:
1.120 markus 1472: /* Parent. Stay in the loop. */
1473: if (pid < 0)
1474: error("fork: %.100s", strerror(errno));
1475: else
1.245 mpech 1476: debug("Forked child %ld.", (long)pid);
1.120 markus 1477:
1478: close(startup_p[1]);
1.1 deraadt 1479:
1.294 djm 1480: if (rexec_flag) {
1481: send_rexec_state(config_s[0], &cfg);
1482: close(config_s[0]);
1483: close(config_s[1]);
1484: }
1485:
1.327 deraadt 1486: /*
1487: * Mark that the key has been used (it
1488: * was "given" to the child).
1489: */
1.151 markus 1490: if ((options.protocol & SSH_PROTO_1) &&
1491: key_used == 0) {
1492: /* Schedule server key regeneration alarm. */
1493: signal(SIGALRM, key_regeneration_alarm);
1494: alarm(options.key_regeneration_time);
1495: key_used = 1;
1496: }
1.1 deraadt 1497:
1.120 markus 1498: arc4random_stir();
1499: close(newsock);
1500: }
1.75 markus 1501: /* child process check (or debug mode) */
1502: if (num_listen_socks < 0)
1503: break;
1.64 markus 1504: }
1.1 deraadt 1505: }
1506:
1.64 markus 1507: /* This is the child processing a new connection. */
1.288 markus 1508: setproctitle("%s", "[accepted]");
1.294 djm 1509:
1.300 markus 1510: /*
1511: * Create a new session and process group since the 4.4BSD
1512: * setlogin() affects the entire process group. We don't
1513: * want the child to be able to affect the parent.
1514: */
1515: if (!debug_flag && !inetd_flag && setsid() < 0)
1516: error("setsid: %.100s", strerror(errno));
1517:
1.294 djm 1518: if (rexec_flag) {
1519: int fd;
1520:
1.296 djm 1521: debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1522: sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1.294 djm 1523: dup2(newsock, STDIN_FILENO);
1524: dup2(STDIN_FILENO, STDOUT_FILENO);
1525: if (startup_pipe == -1)
1.296 djm 1526: close(REEXEC_STARTUP_PIPE_FD);
1.294 djm 1527: else
1.296 djm 1528: dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1.294 djm 1529:
1.296 djm 1530: dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1.294 djm 1531: close(config_s[1]);
1.301 dtucker 1532: if (startup_pipe != -1)
1533: close(startup_pipe);
1.296 djm 1534:
1.294 djm 1535: execv(rexec_argv[0], rexec_argv);
1536:
1537: /* Reexec has failed, fall back and continue */
1538: error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1.296 djm 1539: recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1.294 djm 1540: log_init(__progname, options.log_level,
1541: options.log_facility, log_stderr);
1542:
1543: /* Clean up fds */
1.296 djm 1544: startup_pipe = REEXEC_STARTUP_PIPE_FD;
1.294 djm 1545: close(config_s[1]);
1.296 djm 1546: close(REEXEC_CONFIG_PASS_FD);
1547: newsock = sock_out = sock_in = dup(STDIN_FILENO);
1.294 djm 1548: if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1549: dup2(fd, STDIN_FILENO);
1550: dup2(fd, STDOUT_FILENO);
1551: if (fd > STDERR_FILENO)
1552: close(fd);
1553: }
1.296 djm 1554: debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1555: sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1.294 djm 1556: }
1.64 markus 1557:
1.66 markus 1558: /*
1559: * Disable the key regeneration alarm. We will not regenerate the
1560: * key since we are no longer in a position to give it to anyone. We
1561: * will not restart on SIGHUP since it no longer makes sense.
1562: */
1.64 markus 1563: alarm(0);
1564: signal(SIGALRM, SIG_DFL);
1565: signal(SIGHUP, SIG_DFL);
1566: signal(SIGTERM, SIG_DFL);
1567: signal(SIGQUIT, SIG_DFL);
1568: signal(SIGCHLD, SIG_DFL);
1.150 markus 1569:
1.66 markus 1570: /*
1571: * Register our connection. This turns encryption off because we do
1572: * not have a key.
1573: */
1.64 markus 1574: packet_set_connection(sock_in, sock_out);
1.312 markus 1575: packet_set_server();
1.309 djm 1576:
1577: /* Set SO_KEEPALIVE if requested. */
1578: if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1579: setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1580: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.1 deraadt 1581:
1.310 markus 1582: if ((remote_port = get_remote_port()) < 0) {
1583: debug("get_remote_port failed");
1584: cleanup_exit(255);
1585: }
1.316 dtucker 1586:
1587: /*
1588: * We use get_canonical_hostname with usedns = 0 instead of
1589: * get_remote_ipaddr here so IP options will be checked.
1590: */
1.331 markus 1591: (void) get_canonical_hostname(0);
1592: /*
1593: * The rest of the code depends on the fact that
1594: * get_remote_ipaddr() caches the remote ip, even if
1595: * the socket goes away.
1596: */
1597: remote_ip = get_remote_ipaddr();
1.52 markus 1598:
1.209 markus 1599: #ifdef LIBWRAP
1.64 markus 1600: /* Check whether logins are denied from this host. */
1.295 djm 1601: if (packet_connection_is_on_socket()) {
1.64 markus 1602: struct request_info req;
1.37 dugsong 1603:
1.204 camield 1604: request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1.64 markus 1605: fromhost(&req);
1.37 dugsong 1606:
1.64 markus 1607: if (!hosts_access(&req)) {
1.209 markus 1608: debug("Connection refused by tcp wrapper");
1.182 markus 1609: refuse(&req);
1.209 markus 1610: /* NOTREACHED */
1611: fatal("libwrap refuse returns");
1.64 markus 1612: }
1613: }
1.75 markus 1614: #endif /* LIBWRAP */
1.209 markus 1615:
1.64 markus 1616: /* Log the connection. */
1617: verbose("Connection from %.500s port %d", remote_ip, remote_port);
1.1 deraadt 1618:
1.66 markus 1619: /*
1.317 djm 1620: * We don't want to listen forever unless the other side
1.66 markus 1621: * successfully authenticates itself. So we set up an alarm which is
1622: * cleared after successful authentication. A limit of zero
1.317 djm 1623: * indicates no limit. Note that we don't set the alarm in debugging
1.66 markus 1624: * mode; it is just annoying to have the server exit just when you
1625: * are about to discover the bug.
1626: */
1.64 markus 1627: signal(SIGALRM, grace_alarm_handler);
1628: if (!debug_flag)
1629: alarm(options.login_grace_time);
1630:
1.96 markus 1631: sshd_exchange_identification(sock_in, sock_out);
1.275 markus 1632:
1.64 markus 1633: packet_set_nonblocking();
1.1 deraadt 1634:
1.278 markus 1635: /* allocate authentication context */
1.329 djm 1636: authctxt = xcalloc(1, sizeof(*authctxt));
1.278 markus 1637:
1638: /* XXX global for cleanup, access from other modules */
1639: the_authctxt = authctxt;
1640:
1.307 otto 1641: /* prepare buffer to collect messages to display to user after login */
1642: buffer_init(&loginmsg);
1643:
1.237 markus 1644: if (use_privsep)
1.278 markus 1645: if (privsep_preauth(authctxt) == 1)
1.237 markus 1646: goto authenticated;
1.231 provos 1647:
1.77 markus 1648: /* perform the key exchange */
1649: /* authenticate user and start session */
1.98 markus 1650: if (compat20) {
1651: do_ssh2_kex();
1.278 markus 1652: do_authentication2(authctxt);
1.98 markus 1653: } else {
1654: do_ssh1_kex();
1.278 markus 1655: do_authentication(authctxt);
1.98 markus 1656: }
1.237 markus 1657: /*
1658: * If we use privilege separation, the unprivileged child transfers
1659: * the current keystate and exits
1660: */
1661: if (use_privsep) {
1.242 mouring 1662: mm_send_keystate(pmonitor);
1.231 provos 1663: exit(0);
1.237 markus 1664: }
1.231 provos 1665:
1666: authenticated:
1.318 djm 1667: /*
1668: * Cancel the alarm we set to limit the time taken for
1669: * authentication.
1670: */
1671: alarm(0);
1672: signal(SIGALRM, SIG_DFL);
1673: if (startup_pipe != -1) {
1674: close(startup_pipe);
1675: startup_pipe = -1;
1676: }
1677:
1.234 markus 1678: /*
1.231 provos 1679: * In privilege separation, we fork another child and prepare
1680: * file descriptor passing.
1681: */
1682: if (use_privsep) {
1.237 markus 1683: privsep_postauth(authctxt);
1684: /* the monitor process [priv] will not return */
1.231 provos 1685: if (!compat20)
1686: destroy_sensitive_data();
1687: }
1.230 provos 1688:
1.278 markus 1689: /* Start session. */
1.230 provos 1690: do_authenticated(authctxt);
1691:
1.64 markus 1692: /* The connection has been terminated. */
1693: verbose("Closing connection to %.100s", remote_ip);
1694: packet_close();
1.231 provos 1695:
1696: if (use_privsep)
1697: mm_terminate();
1698:
1.64 markus 1699: exit(0);
1.1 deraadt 1700: }
1701:
1.65 deraadt 1702: /*
1.229 markus 1703: * Decrypt session_key_int using our private server key and private host key
1704: * (key with larger modulus first).
1705: */
1.231 provos 1706: int
1.229 markus 1707: ssh1_session_key(BIGNUM *session_key_int)
1708: {
1709: int rsafail = 0;
1710:
1.327 deraadt 1711: if (BN_cmp(sensitive_data.server_key->rsa->n,
1712: sensitive_data.ssh1_host_key->rsa->n) > 0) {
1.229 markus 1713: /* Server key has bigger modulus. */
1714: if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1.327 deraadt 1715: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1716: SSH_KEY_BITS_RESERVED) {
1717: fatal("do_connection: %s: "
1718: "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1.229 markus 1719: get_remote_ipaddr(),
1720: BN_num_bits(sensitive_data.server_key->rsa->n),
1721: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1722: SSH_KEY_BITS_RESERVED);
1723: }
1724: if (rsa_private_decrypt(session_key_int, session_key_int,
1725: sensitive_data.server_key->rsa) <= 0)
1726: rsafail++;
1727: if (rsa_private_decrypt(session_key_int, session_key_int,
1728: sensitive_data.ssh1_host_key->rsa) <= 0)
1729: rsafail++;
1730: } else {
1731: /* Host key has bigger modulus (or they are equal). */
1732: if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1.327 deraadt 1733: BN_num_bits(sensitive_data.server_key->rsa->n) +
1734: SSH_KEY_BITS_RESERVED) {
1735: fatal("do_connection: %s: "
1736: "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1.229 markus 1737: get_remote_ipaddr(),
1738: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1739: BN_num_bits(sensitive_data.server_key->rsa->n),
1740: SSH_KEY_BITS_RESERVED);
1741: }
1742: if (rsa_private_decrypt(session_key_int, session_key_int,
1743: sensitive_data.ssh1_host_key->rsa) < 0)
1744: rsafail++;
1745: if (rsa_private_decrypt(session_key_int, session_key_int,
1746: sensitive_data.server_key->rsa) < 0)
1747: rsafail++;
1748: }
1749: return (rsafail);
1750: }
1751: /*
1.77 markus 1752: * SSH1 key exchange
1.65 deraadt 1753: */
1.200 itojun 1754: static void
1.142 markus 1755: do_ssh1_kex(void)
1.1 deraadt 1756: {
1.64 markus 1757: int i, len;
1.159 markus 1758: int rsafail = 0;
1.64 markus 1759: BIGNUM *session_key_int;
1.140 markus 1760: u_char session_key[SSH_SESSION_KEY_LENGTH];
1761: u_char cookie[8];
1762: u_int cipher_type, auth_mask, protocol_flags;
1.254 deraadt 1763: u_int32_t rnd = 0;
1.64 markus 1764:
1.66 markus 1765: /*
1766: * Generate check bytes that the client must send back in the user
1767: * packet in order for it to be accepted; this is used to defy ip
1768: * spoofing attacks. Note that this only works against somebody
1769: * doing IP spoofing from a remote machine; any machine on the local
1770: * network can still see outgoing packets and catch the random
1771: * cookie. This only affects rhosts authentication, and this is one
1772: * of the reasons why it is inherently insecure.
1773: */
1.64 markus 1774: for (i = 0; i < 8; i++) {
1775: if (i % 4 == 0)
1.254 deraadt 1776: rnd = arc4random();
1777: cookie[i] = rnd & 0xff;
1778: rnd >>= 8;
1.64 markus 1779: }
1780:
1.66 markus 1781: /*
1782: * Send our public key. We include in the packet 64 bits of random
1783: * data that must be matched in the reply in order to prevent IP
1784: * spoofing.
1785: */
1.64 markus 1786: packet_start(SSH_SMSG_PUBLIC_KEY);
1787: for (i = 0; i < 8; i++)
1.77 markus 1788: packet_put_char(cookie[i]);
1.64 markus 1789:
1790: /* Store our public server RSA key. */
1.134 markus 1791: packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1792: packet_put_bignum(sensitive_data.server_key->rsa->e);
1793: packet_put_bignum(sensitive_data.server_key->rsa->n);
1.64 markus 1794:
1795: /* Store our public host RSA key. */
1.134 markus 1796: packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1797: packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1798: packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1.64 markus 1799:
1800: /* Put protocol flags. */
1801: packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1802:
1803: /* Declare which ciphers we support. */
1.131 markus 1804: packet_put_int(cipher_mask_ssh1(0));
1.64 markus 1805:
1806: /* Declare supported authentication types. */
1807: auth_mask = 0;
1808: if (options.rhosts_rsa_authentication)
1809: auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1810: if (options.rsa_authentication)
1811: auth_mask |= 1 << SSH_AUTH_RSA;
1.196 markus 1812: if (options.challenge_response_authentication == 1)
1.64 markus 1813: auth_mask |= 1 << SSH_AUTH_TIS;
1814: if (options.password_authentication)
1815: auth_mask |= 1 << SSH_AUTH_PASSWORD;
1816: packet_put_int(auth_mask);
1817:
1818: /* Send the packet and wait for it to be sent. */
1819: packet_send();
1820: packet_write_wait();
1821:
1.134 markus 1822: debug("Sent %d bit server key and %d bit host key.",
1823: BN_num_bits(sensitive_data.server_key->rsa->n),
1824: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1.64 markus 1825:
1826: /* Read clients reply (cipher type and session key). */
1.222 markus 1827: packet_read_expect(SSH_CMSG_SESSION_KEY);
1.64 markus 1828:
1.69 markus 1829: /* Get cipher type and check whether we accept this. */
1.64 markus 1830: cipher_type = packet_get_char();
1.69 markus 1831:
1.131 markus 1832: if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1.69 markus 1833: packet_disconnect("Warning: client selects unsupported cipher.");
1.64 markus 1834:
1835: /* Get check bytes from the packet. These must match those we
1836: sent earlier with the public key packet. */
1837: for (i = 0; i < 8; i++)
1.77 markus 1838: if (cookie[i] != packet_get_char())
1.64 markus 1839: packet_disconnect("IP Spoofing check bytes do not match.");
1840:
1841: debug("Encryption type: %.200s", cipher_name(cipher_type));
1842:
1843: /* Get the encrypted integer. */
1.218 markus 1844: if ((session_key_int = BN_new()) == NULL)
1845: fatal("do_ssh1_kex: BN_new failed");
1.221 markus 1846: packet_get_bignum(session_key_int);
1.64 markus 1847:
1848: protocol_flags = packet_get_int();
1849: packet_set_protocol_flags(protocol_flags);
1.220 markus 1850: packet_check_eom();
1.64 markus 1851:
1.229 markus 1852: /* Decrypt session_key_int using host/server keys */
1.231 provos 1853: rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1854:
1.66 markus 1855: /*
1856: * Extract session key from the decrypted integer. The key is in the
1857: * least significant 256 bits of the integer; the first byte of the
1858: * key is in the highest bits.
1859: */
1.159 markus 1860: if (!rsafail) {
1861: BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1862: len = BN_num_bytes(session_key_int);
1.311 djm 1863: if (len < 0 || (u_int)len > sizeof(session_key)) {
1.159 markus 1864: error("do_connection: bad session key len from %s: "
1.165 itojun 1865: "session_key_int %d > sizeof(session_key) %lu",
1866: get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1.159 markus 1867: rsafail++;
1868: } else {
1869: memset(session_key, 0, sizeof(session_key));
1870: BN_bn2bin(session_key_int,
1871: session_key + sizeof(session_key) - len);
1.169 markus 1872:
1.291 djm 1873: derive_ssh1_session_id(
1.298 deraadt 1874: sensitive_data.ssh1_host_key->rsa->n,
1.291 djm 1875: sensitive_data.server_key->rsa->n,
1876: cookie, session_id);
1.169 markus 1877: /*
1878: * Xor the first 16 bytes of the session key with the
1879: * session id.
1880: */
1881: for (i = 0; i < 16; i++)
1882: session_key[i] ^= session_id[i];
1.159 markus 1883: }
1884: }
1885: if (rsafail) {
1.169 markus 1886: int bytes = BN_num_bytes(session_key_int);
1.227 stevesk 1887: u_char *buf = xmalloc(bytes);
1.169 markus 1888: MD5_CTX md;
1889:
1.264 itojun 1890: logit("do_connection: generating a fake encryption key");
1.169 markus 1891: BN_bn2bin(session_key_int, buf);
1892: MD5_Init(&md);
1893: MD5_Update(&md, buf, bytes);
1894: MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1895: MD5_Final(session_key, &md);
1896: MD5_Init(&md);
1897: MD5_Update(&md, session_key, 16);
1898: MD5_Update(&md, buf, bytes);
1899: MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1900: MD5_Final(session_key + 16, &md);
1901: memset(buf, 0, bytes);
1902: xfree(buf);
1.170 markus 1903: for (i = 0; i < 16; i++)
1904: session_id[i] = session_key[i] ^ session_key[i + 16];
1.159 markus 1905: }
1.231 provos 1906: /* Destroy the private and public keys. No longer. */
1.169 markus 1907: destroy_sensitive_data();
1908:
1.231 provos 1909: if (use_privsep)
1910: mm_ssh1_session_id(session_id);
1911:
1.77 markus 1912: /* Destroy the decrypted integer. It is no longer needed. */
1913: BN_clear_free(session_key_int);
1.64 markus 1914:
1915: /* Set the session key. From this on all communications will be encrypted. */
1916: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1917:
1918: /* Destroy our copy of the session key. It is no longer needed. */
1919: memset(session_key, 0, sizeof(session_key));
1920:
1921: debug("Received session key; encryption turned on.");
1922:
1.243 deraadt 1923: /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1.64 markus 1924: packet_start(SSH_SMSG_SUCCESS);
1925: packet_send();
1926: packet_write_wait();
1.98 markus 1927: }
1928:
1929: /*
1930: * SSH2 key exchange: diffie-hellman-group1-sha1
1931: */
1.200 itojun 1932: static void
1.142 markus 1933: do_ssh2_kex(void)
1.98 markus 1934: {
1935: Kex *kex;
1.102 markus 1936:
1937: if (options.ciphers != NULL) {
1.105 markus 1938: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1.102 markus 1939: myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1.166 markus 1940: }
1.184 stevesk 1941: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1942: compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1943: myproposal[PROPOSAL_ENC_ALGS_STOC] =
1944: compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1945:
1.166 markus 1946: if (options.macs != NULL) {
1947: myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1948: myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1.246 markus 1949: }
1.312 markus 1950: if (options.compression == COMP_NONE) {
1.246 markus 1951: myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1952: myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1.312 markus 1953: } else if (options.compression == COMP_DELAYED) {
1954: myproposal[PROPOSAL_COMP_ALGS_CTOS] =
1955: myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
1.102 markus 1956: }
1.327 deraadt 1957:
1.134 markus 1958: myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1959:
1.189 markus 1960: /* start key exchange */
1.188 markus 1961: kex = kex_setup(myproposal);
1.263 markus 1962: kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
1.292 djm 1963: kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
1.263 markus 1964: kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1.324 djm 1965: kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
1.186 markus 1966: kex->server = 1;
1967: kex->client_version_string=client_version_string;
1968: kex->server_version_string=server_version_string;
1969: kex->load_host_key=&get_hostkey_by_type;
1.231 provos 1970: kex->host_key_index=&get_hostkey_index;
1.129 provos 1971:
1.189 markus 1972: xxx_kex = kex;
1973:
1.190 markus 1974: dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
1.187 markus 1975:
1976: session_id2 = kex->session_id;
1977: session_id2_len = kex->session_id_len;
1.129 provos 1978:
1979: #ifdef DEBUG_KEXDH
1980: /* send 1st encrypted/maced/compressed message */
1981: packet_start(SSH2_MSG_IGNORE);
1982: packet_put_cstring("markus");
1983: packet_send();
1984: packet_write_wait();
1985: #endif
1.186 markus 1986: debug("KEX done");
1.278 markus 1987: }
1988:
1989: /* server specific fatal cleanup */
1990: void
1991: cleanup_exit(int i)
1992: {
1993: if (the_authctxt)
1994: do_cleanup(the_authctxt);
1995: _exit(i);
1.1 deraadt 1996: }
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