Annotation of src/usr.bin/ssh/sshd.c, Revision 1.369
1.369 ! dtucker 1: /* $OpenBSD: sshd.c,v 1.368 2009/10/28 16:38:18 reyk 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:
1.343 deraadt 45: #include <sys/types.h>
1.320 stevesk 46: #include <sys/ioctl.h>
1.321 stevesk 47: #include <sys/wait.h>
1.343 deraadt 48: #include <sys/tree.h>
1.323 stevesk 49: #include <sys/stat.h>
1.334 stevesk 50: #include <sys/socket.h>
1.340 stevesk 51: #include <sys/time.h>
1.357 djm 52: #include <sys/queue.h>
1.319 stevesk 53:
1.336 stevesk 54: #include <errno.h>
1.335 stevesk 55: #include <fcntl.h>
1.338 stevesk 56: #include <netdb.h>
1.319 stevesk 57: #include <paths.h>
1.333 stevesk 58: #include <pwd.h>
1.322 stevesk 59: #include <signal.h>
1.342 stevesk 60: #include <stdio.h>
1.341 stevesk 61: #include <stdlib.h>
1.339 stevesk 62: #include <string.h>
1.344 dtucker 63: #include <unistd.h>
1.1 deraadt 64:
1.155 markus 65: #include <openssl/dh.h>
66: #include <openssl/bn.h>
1.226 markus 67: #include <openssl/md5.h>
1.231 provos 68: #include <openssl/rand.h>
1.155 markus 69:
1.343 deraadt 70: #include "xmalloc.h"
1.155 markus 71: #include "ssh.h"
72: #include "ssh1.h"
73: #include "ssh2.h"
1.1 deraadt 74: #include "rsa.h"
1.171 djm 75: #include "sshpty.h"
1.1 deraadt 76: #include "packet.h"
1.155 markus 77: #include "log.h"
1.343 deraadt 78: #include "buffer.h"
1.1 deraadt 79: #include "servconf.h"
80: #include "uidswap.h"
1.33 markus 81: #include "compat.h"
1.155 markus 82: #include "cipher.h"
1.343 deraadt 83: #include "key.h"
1.98 markus 84: #include "kex.h"
1.129 provos 85: #include "dh.h"
1.98 markus 86: #include "myproposal.h"
1.108 markus 87: #include "authfile.h"
1.154 markus 88: #include "pathnames.h"
1.155 markus 89: #include "atomicio.h"
90: #include "canohost.h"
1.343 deraadt 91: #include "hostfile.h"
1.155 markus 92: #include "auth.h"
93: #include "misc.h"
1.294 djm 94: #include "msg.h"
1.186 markus 95: #include "dispatch.h"
1.206 stevesk 96: #include "channels.h"
1.230 provos 97: #include "session.h"
1.231 provos 98: #include "monitor_mm.h"
99: #include "monitor.h"
1.343 deraadt 100: #ifdef GSSAPI
101: #include "ssh-gss.h"
102: #endif
1.231 provos 103: #include "monitor_wrap.h"
1.367 andreas 104: #include "roaming.h"
1.332 stevesk 105: #include "version.h"
1.1 deraadt 106:
107: #ifdef LIBWRAP
108: #include <tcpd.h>
109: #include <syslog.h>
110: int allow_severity = LOG_INFO;
111: int deny_severity = LOG_WARNING;
112: #endif /* LIBWRAP */
113:
114: #ifndef O_NOCTTY
115: #define O_NOCTTY 0
116: #endif
117:
1.296 djm 118: /* Re-exec fds */
119: #define REEXEC_DEVCRYPTO_RESERVED_FD (STDERR_FILENO + 1)
120: #define REEXEC_STARTUP_PIPE_FD (STDERR_FILENO + 2)
121: #define REEXEC_CONFIG_PASS_FD (STDERR_FILENO + 3)
122: #define REEXEC_MIN_FREE_FD (STDERR_FILENO + 4)
123:
1.138 markus 124: extern char *__progname;
125:
1.1 deraadt 126: /* Server configuration options. */
127: ServerOptions options;
128:
129: /* Name of the server configuration file. */
1.154 markus 130: char *config_file_name = _PATH_SERVER_CONFIG_FILE;
1.1 deraadt 131:
1.105 markus 132: /*
1.65 deraadt 133: * Debug mode flag. This can be set on the command line. If debug
134: * mode is enabled, extra debugging output will be sent to the system
135: * log, the daemon will not go to background, and will exit after processing
136: * the first connection.
137: */
1.1 deraadt 138: int debug_flag = 0;
139:
1.203 stevesk 140: /* Flag indicating that the daemon should only test the configuration and keys. */
141: int test_flag = 0;
142:
1.1 deraadt 143: /* Flag indicating that the daemon is being started from inetd. */
144: int inetd_flag = 0;
145:
1.135 markus 146: /* Flag indicating that sshd should not detach and become a daemon. */
147: int no_daemon_flag = 0;
148:
1.47 markus 149: /* debug goes to stderr unless inetd_flag is set */
150: int log_stderr = 0;
151:
1.1 deraadt 152: /* Saved arguments to main(). */
153: char **saved_argv;
154:
1.294 djm 155: /* re-exec */
156: int rexeced_flag = 0;
157: int rexec_flag = 1;
158: int rexec_argc = 0;
159: char **rexec_argv;
160:
1.66 markus 161: /*
1.75 markus 162: * The sockets that the server is listening; this is used in the SIGHUP
163: * signal handler.
1.66 markus 164: */
1.75 markus 165: #define MAX_LISTEN_SOCKS 16
166: int listen_socks[MAX_LISTEN_SOCKS];
167: int num_listen_socks = 0;
1.1 deraadt 168:
1.66 markus 169: /*
170: * the client's version string, passed by sshd2 in compat mode. if != NULL,
171: * sshd will skip the version-number exchange
172: */
1.61 markus 173: char *client_version_string = NULL;
1.96 markus 174: char *server_version_string = NULL;
1.1 deraadt 175:
1.189 markus 176: /* for rekeying XXX fixme */
177: Kex *xxx_kex;
178:
1.66 markus 179: /*
180: * Any really sensitive data in the application is contained in this
181: * structure. The idea is that this structure could be locked into memory so
182: * that the pages do not get written into swap. However, there are some
183: * problems. The private key contains BIGNUMs, and we do not (in principle)
184: * have access to the internals of them, and locking just the structure is
185: * not very useful. Currently, memory locking is not implemented.
186: */
1.64 markus 187: struct {
1.174 deraadt 188: Key *server_key; /* ephemeral server key */
1.134 markus 189: Key *ssh1_host_key; /* ssh1 host key */
190: Key **host_keys; /* all private host keys */
191: int have_ssh1_key;
192: int have_ssh2_key;
1.169 markus 193: u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
1.1 deraadt 194: } sensitive_data;
195:
1.66 markus 196: /*
1.151 markus 197: * Flag indicating whether the RSA server key needs to be regenerated.
198: * Is set in the SIGALRM handler and cleared when the key is regenerated.
1.66 markus 199: */
1.212 markus 200: static volatile sig_atomic_t key_do_regen = 0;
1.1 deraadt 201:
1.199 markus 202: /* This is set to true when a signal is received. */
1.212 markus 203: static volatile sig_atomic_t received_sighup = 0;
204: static volatile sig_atomic_t received_sigterm = 0;
1.1 deraadt 205:
1.96 markus 206: /* session identifier, used by RSA-auth */
1.140 markus 207: u_char session_id[16];
1.96 markus 208:
1.108 markus 209: /* same for ssh2 */
1.140 markus 210: u_char *session_id2 = NULL;
1.269 markus 211: u_int session_id2_len = 0;
1.108 markus 212:
1.125 markus 213: /* record remote hostname or ip */
1.140 markus 214: u_int utmp_len = MAXHOSTNAMELEN;
1.125 markus 215:
1.211 markus 216: /* options.max_startup sized array of fd ints */
217: int *startup_pipes = NULL;
218: int startup_pipe; /* in child */
219:
1.231 provos 220: /* variables used for privilege separation */
1.337 dtucker 221: int use_privsep = -1;
1.285 dtucker 222: struct monitor *pmonitor = NULL;
1.231 provos 223:
1.278 markus 224: /* global authentication context */
225: Authctxt *the_authctxt = NULL;
226:
1.337 dtucker 227: /* sshd_config buffer */
228: Buffer cfg;
229:
1.299 dtucker 230: /* message to be displayed after login */
231: Buffer loginmsg;
232:
1.1 deraadt 233: /* Prototypes for various functions defined later in this file. */
1.200 itojun 234: void destroy_sensitive_data(void);
1.231 provos 235: void demote_sensitive_data(void);
1.87 markus 236:
1.200 itojun 237: static void do_ssh1_kex(void);
238: static void do_ssh2_kex(void);
1.129 provos 239:
1.87 markus 240: /*
1.75 markus 241: * Close all listening sockets
242: */
1.200 itojun 243: static void
1.75 markus 244: close_listen_socks(void)
245: {
246: int i;
1.250 deraadt 247:
1.75 markus 248: for (i = 0; i < num_listen_socks; i++)
249: close(listen_socks[i]);
250: num_listen_socks = -1;
251: }
252:
1.211 markus 253: static void
254: close_startup_pipes(void)
255: {
256: int i;
1.250 deraadt 257:
1.211 markus 258: if (startup_pipes)
259: for (i = 0; i < options.max_startups; i++)
260: if (startup_pipes[i] != -1)
261: close(startup_pipes[i]);
262: }
263:
1.75 markus 264: /*
1.65 deraadt 265: * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
266: * the effect is to reread the configuration file (and to regenerate
267: * the server key).
268: */
1.327 deraadt 269:
270: /*ARGSUSED*/
1.200 itojun 271: static void
1.64 markus 272: sighup_handler(int sig)
1.1 deraadt 273: {
1.210 deraadt 274: int save_errno = errno;
275:
1.64 markus 276: received_sighup = 1;
277: signal(SIGHUP, sighup_handler);
1.210 deraadt 278: errno = save_errno;
1.1 deraadt 279: }
280:
1.65 deraadt 281: /*
282: * Called from the main program after receiving SIGHUP.
283: * Restarts the server.
284: */
1.200 itojun 285: static void
1.165 itojun 286: sighup_restart(void)
1.1 deraadt 287: {
1.264 itojun 288: logit("Received SIGHUP; restarting.");
1.75 markus 289: close_listen_socks();
1.211 markus 290: close_startup_pipes();
1.349 dtucker 291: alarm(0); /* alarm timer persists across exec */
1.369 ! dtucker 292: signal(SIGHUP, SIG_IGN); /* will be restored after exec */
1.64 markus 293: execv(saved_argv[0], saved_argv);
1.264 itojun 294: logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
1.250 deraadt 295: strerror(errno));
1.64 markus 296: exit(1);
1.1 deraadt 297: }
298:
1.65 deraadt 299: /*
300: * Generic signal handler for terminating signals in the master daemon.
301: */
1.327 deraadt 302: /*ARGSUSED*/
1.200 itojun 303: static void
1.64 markus 304: sigterm_handler(int sig)
1.1 deraadt 305: {
1.199 markus 306: received_sigterm = sig;
1.1 deraadt 307: }
308:
1.65 deraadt 309: /*
310: * SIGCHLD handler. This is called whenever a child dies. This will then
1.199 markus 311: * reap any zombies left by exited children.
1.65 deraadt 312: */
1.327 deraadt 313: /*ARGSUSED*/
1.200 itojun 314: static void
1.64 markus 315: main_sigchld_handler(int sig)
1.1 deraadt 316: {
1.250 deraadt 317: int save_errno = errno;
1.239 markus 318: pid_t pid;
1.64 markus 319: int status;
1.60 deraadt 320:
1.239 markus 321: while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
322: (pid < 0 && errno == EINTR))
1.64 markus 323: ;
1.60 deraadt 324:
1.64 markus 325: signal(SIGCHLD, main_sigchld_handler);
326: errno = save_errno;
1.1 deraadt 327: }
328:
1.65 deraadt 329: /*
330: * Signal handler for the alarm after the login grace period has expired.
331: */
1.327 deraadt 332: /*ARGSUSED*/
1.200 itojun 333: static void
1.64 markus 334: grace_alarm_handler(int sig)
1.1 deraadt 335: {
1.285 dtucker 336: if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
337: kill(pmonitor->m_pid, SIGALRM);
338:
1.64 markus 339: /* Log error and exit. */
1.346 deraadt 340: sigdie("Timeout before authentication for %s", get_remote_ipaddr());
1.62 markus 341: }
342:
1.65 deraadt 343: /*
344: * Signal handler for the key regeneration alarm. Note that this
345: * alarm only occurs in the daemon waiting for connections, and it does not
346: * do anything with the private key or random state before forking.
347: * Thus there should be no concurrency control/asynchronous execution
348: * problems.
349: */
1.200 itojun 350: static void
1.174 deraadt 351: generate_ephemeral_server_key(void)
1.134 markus 352: {
1.191 markus 353: verbose("Generating %s%d bit RSA key.",
1.185 djm 354: sensitive_data.server_key ? "new " : "", options.server_key_bits);
1.134 markus 355: if (sensitive_data.server_key != NULL)
356: key_free(sensitive_data.server_key);
1.191 markus 357: sensitive_data.server_key = key_generate(KEY_RSA1,
1.185 djm 358: options.server_key_bits);
359: verbose("RSA key generation complete.");
1.169 markus 360:
1.356 djm 361: arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1.134 markus 362: arc4random_stir();
363: }
1.147 deraadt 364:
1.327 deraadt 365: /*ARGSUSED*/
1.200 itojun 366: static void
1.64 markus 367: key_regeneration_alarm(int sig)
1.1 deraadt 368: {
1.64 markus 369: int save_errno = errno;
1.250 deraadt 370:
1.151 markus 371: signal(SIGALRM, SIG_DFL);
1.64 markus 372: errno = save_errno;
1.151 markus 373: key_do_regen = 1;
1.98 markus 374: }
375:
1.200 itojun 376: static void
1.96 markus 377: sshd_exchange_identification(int sock_in, int sock_out)
378: {
1.311 djm 379: u_int i;
380: int mismatch;
1.96 markus 381: int remote_major, remote_minor;
1.102 markus 382: int major, minor;
1.363 dtucker 383: char *s, *newline = "\n";
1.96 markus 384: char buf[256]; /* Must not be larger than remote_version. */
385: char remote_version[256]; /* Must be at least as big as buf. */
386:
1.103 markus 387: if ((options.protocol & SSH_PROTO_1) &&
388: (options.protocol & SSH_PROTO_2)) {
1.102 markus 389: major = PROTOCOL_MAJOR_1;
390: minor = 99;
391: } else if (options.protocol & SSH_PROTO_2) {
392: major = PROTOCOL_MAJOR_2;
393: minor = PROTOCOL_MINOR_2;
1.363 dtucker 394: newline = "\r\n";
1.102 markus 395: } else {
396: major = PROTOCOL_MAJOR_1;
397: minor = PROTOCOL_MINOR_1;
398: }
1.363 dtucker 399: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
400: SSH_VERSION, newline);
1.96 markus 401: server_version_string = xstrdup(buf);
402:
1.272 markus 403: /* Send our protocol version identification. */
1.367 andreas 404: if (roaming_atomicio(vwrite, sock_out, server_version_string,
1.272 markus 405: strlen(server_version_string))
406: != strlen(server_version_string)) {
407: logit("Could not write ident string to %s", get_remote_ipaddr());
1.278 markus 408: cleanup_exit(255);
1.272 markus 409: }
410:
411: /* Read other sides version identification. */
412: memset(buf, 0, sizeof(buf));
413: for (i = 0; i < sizeof(buf) - 1; i++) {
1.367 andreas 414: if (roaming_atomicio(read, sock_in, &buf[i], 1) != 1) {
1.272 markus 415: logit("Did not receive identification string from %s",
416: get_remote_ipaddr());
1.278 markus 417: cleanup_exit(255);
1.96 markus 418: }
1.272 markus 419: if (buf[i] == '\r') {
420: buf[i] = 0;
421: /* Kludge for F-Secure Macintosh < 1.0.2 */
422: if (i == 12 &&
423: strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
1.96 markus 424: break;
1.272 markus 425: continue;
426: }
427: if (buf[i] == '\n') {
428: buf[i] = 0;
429: break;
1.96 markus 430: }
431: }
1.272 markus 432: buf[sizeof(buf) - 1] = 0;
433: client_version_string = xstrdup(buf);
1.96 markus 434:
435: /*
436: * Check that the versions match. In future this might accept
437: * several versions and set appropriate flags to handle them.
438: */
439: if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
440: &remote_major, &remote_minor, remote_version) != 3) {
1.105 markus 441: s = "Protocol mismatch.\n";
1.271 deraadt 442: (void) atomicio(vwrite, sock_out, s, strlen(s));
1.96 markus 443: close(sock_in);
444: close(sock_out);
1.264 itojun 445: logit("Bad protocol version identification '%.100s' from %s",
1.96 markus 446: client_version_string, get_remote_ipaddr());
1.278 markus 447: cleanup_exit(255);
1.96 markus 448: }
449: debug("Client protocol version %d.%d; client software version %.100s",
1.217 deraadt 450: remote_major, remote_minor, remote_version);
1.96 markus 451:
1.98 markus 452: compat_datafellows(remote_version);
1.260 mickey 453:
454: if (datafellows & SSH_BUG_PROBE) {
1.264 itojun 455: logit("probed from %s with %s. Don't panic.",
1.260 mickey 456: get_remote_ipaddr(), client_version_string);
1.278 markus 457: cleanup_exit(255);
1.260 mickey 458: }
1.175 deraadt 459:
460: if (datafellows & SSH_BUG_SCANNER) {
1.264 itojun 461: logit("scanned from %s with %s. Don't panic.",
1.175 deraadt 462: get_remote_ipaddr(), client_version_string);
1.278 markus 463: cleanup_exit(255);
1.175 deraadt 464: }
1.98 markus 465:
1.102 markus 466: mismatch = 0;
1.214 deraadt 467: switch (remote_major) {
1.96 markus 468: case 1:
1.108 markus 469: if (remote_minor == 99) {
470: if (options.protocol & SSH_PROTO_2)
471: enable_compat20();
472: else
473: mismatch = 1;
474: break;
475: }
1.102 markus 476: if (!(options.protocol & SSH_PROTO_1)) {
477: mismatch = 1;
478: break;
479: }
1.96 markus 480: if (remote_minor < 3) {
1.121 provos 481: packet_disconnect("Your ssh version is too old and "
1.96 markus 482: "is no longer supported. Please install a newer version.");
483: } else if (remote_minor == 3) {
484: /* note that this disables agent-forwarding */
485: enable_compat13();
486: }
1.102 markus 487: break;
1.98 markus 488: case 2:
1.102 markus 489: if (options.protocol & SSH_PROTO_2) {
1.98 markus 490: enable_compat20();
491: break;
492: }
1.99 markus 493: /* FALLTHROUGH */
1.105 markus 494: default:
1.102 markus 495: mismatch = 1;
496: break;
497: }
498: chop(server_version_string);
499: debug("Local version string %.200s", server_version_string);
500:
501: if (mismatch) {
1.96 markus 502: s = "Protocol major versions differ.\n";
1.271 deraadt 503: (void) atomicio(vwrite, sock_out, s, strlen(s));
1.96 markus 504: close(sock_in);
505: close(sock_out);
1.264 itojun 506: logit("Protocol major versions differ for %s: %.200s vs. %.200s",
1.102 markus 507: get_remote_ipaddr(),
508: server_version_string, client_version_string);
1.278 markus 509: cleanup_exit(255);
1.96 markus 510: }
1.108 markus 511: }
512:
1.134 markus 513: /* Destroy the host and server keys. They will no longer be needed. */
1.108 markus 514: void
515: destroy_sensitive_data(void)
516: {
1.134 markus 517: int i;
518:
519: if (sensitive_data.server_key) {
520: key_free(sensitive_data.server_key);
521: sensitive_data.server_key = NULL;
522: }
1.217 deraadt 523: for (i = 0; i < options.num_host_key_files; i++) {
1.134 markus 524: if (sensitive_data.host_keys[i]) {
525: key_free(sensitive_data.host_keys[i]);
526: sensitive_data.host_keys[i] = NULL;
527: }
528: }
529: sensitive_data.ssh1_host_key = NULL;
1.169 markus 530: memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
1.134 markus 531: }
532:
1.231 provos 533: /* Demote private to public keys for network child */
534: void
535: demote_sensitive_data(void)
536: {
537: Key *tmp;
538: int i;
539:
540: if (sensitive_data.server_key) {
541: tmp = key_demote(sensitive_data.server_key);
542: key_free(sensitive_data.server_key);
543: sensitive_data.server_key = tmp;
544: }
545:
546: for (i = 0; i < options.num_host_key_files; i++) {
547: if (sensitive_data.host_keys[i]) {
548: tmp = key_demote(sensitive_data.host_keys[i]);
549: key_free(sensitive_data.host_keys[i]);
550: sensitive_data.host_keys[i] = tmp;
551: if (tmp->type == KEY_RSA1)
552: sensitive_data.ssh1_host_key = tmp;
553: }
554: }
555:
556: /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
557: }
558:
1.233 markus 559: static void
1.231 provos 560: privsep_preauth_child(void)
561: {
1.254 deraadt 562: u_int32_t rnd[256];
1.253 deraadt 563: gid_t gidset[1];
1.250 deraadt 564: struct passwd *pw;
1.231 provos 565:
566: /* Enable challenge-response authentication for privilege separation */
567: privsep_challenge_enable();
568:
1.354 djm 569: arc4random_stir();
1.356 djm 570: arc4random_buf(rnd, sizeof(rnd));
1.254 deraadt 571: RAND_seed(rnd, sizeof(rnd));
1.231 provos 572:
573: /* Demote the private keys to public keys. */
574: demote_sensitive_data();
575:
1.235 stevesk 576: if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1.240 djm 577: fatal("Privilege separation user %s does not exist",
578: SSH_PRIVSEP_USER);
1.235 stevesk 579: memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
580: endpwent();
581:
1.255 deraadt 582: /* Change our root directory */
1.232 stevesk 583: if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
584: fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
585: strerror(errno));
1.231 provos 586: if (chdir("/") == -1)
1.236 stevesk 587: fatal("chdir(\"/\"): %s", strerror(errno));
1.234 markus 588:
1.231 provos 589: /* Drop our privileges */
1.235 stevesk 590: debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
591: (u_int)pw->pw_gid);
1.251 markus 592: #if 0
1.287 djm 593: /* XXX not ready, too heavy after chroot */
1.235 stevesk 594: do_setusercontext(pw);
1.251 markus 595: #else
596: gidset[0] = pw->pw_gid;
597: if (setgroups(1, gidset) < 0)
598: fatal("setgroups: %.100s", strerror(errno));
599: permanently_set_uid(pw);
600: #endif
1.231 provos 601: }
602:
1.278 markus 603: static int
604: privsep_preauth(Authctxt *authctxt)
1.237 markus 605: {
606: int status;
607: pid_t pid;
608:
609: /* Set up unprivileged child process to deal with network data */
1.242 mouring 610: pmonitor = monitor_init();
1.237 markus 611: /* Store a pointer to the kex for later rekeying */
1.242 mouring 612: pmonitor->m_pkex = &xxx_kex;
1.237 markus 613:
614: pid = fork();
615: if (pid == -1) {
616: fatal("fork of unprivileged child failed");
617: } else if (pid != 0) {
1.245 mpech 618: debug2("Network child is on pid %ld", (long)pid);
1.237 markus 619:
1.242 mouring 620: close(pmonitor->m_recvfd);
1.285 dtucker 621: pmonitor->m_pid = pid;
1.278 markus 622: monitor_child_preauth(authctxt, pmonitor);
1.242 mouring 623: close(pmonitor->m_sendfd);
1.237 markus 624:
625: /* Sync memory */
1.242 mouring 626: monitor_sync(pmonitor);
1.237 markus 627:
628: /* Wait for the child's exit status */
1.239 markus 629: while (waitpid(pid, &status, 0) < 0)
630: if (errno != EINTR)
631: break;
1.278 markus 632: return (1);
1.237 markus 633: } else {
634: /* child */
635:
1.242 mouring 636: close(pmonitor->m_sendfd);
1.237 markus 637:
638: /* Demote the child */
639: if (getuid() == 0 || geteuid() == 0)
640: privsep_preauth_child();
1.238 stevesk 641: setproctitle("%s", "[net]");
1.237 markus 642: }
1.278 markus 643: return (0);
1.237 markus 644: }
645:
1.233 markus 646: static void
1.237 markus 647: privsep_postauth(Authctxt *authctxt)
1.231 provos 648: {
1.354 djm 649: u_int32_t rnd[256];
650:
1.231 provos 651: if (authctxt->pw->pw_uid == 0 || options.use_login) {
652: /* File descriptor passing is broken or root login */
653: use_privsep = 0;
1.315 djm 654: goto skip;
1.231 provos 655: }
1.234 markus 656:
1.231 provos 657: /* New socket pair */
1.242 mouring 658: monitor_reinit(pmonitor);
1.231 provos 659:
1.242 mouring 660: pmonitor->m_pid = fork();
661: if (pmonitor->m_pid == -1)
1.231 provos 662: fatal("fork of unprivileged child failed");
1.242 mouring 663: else if (pmonitor->m_pid != 0) {
1.364 markus 664: verbose("User child is on pid %ld", (long)pmonitor->m_pid);
1.242 mouring 665: close(pmonitor->m_recvfd);
1.307 otto 666: buffer_clear(&loginmsg);
1.242 mouring 667: monitor_child_postauth(pmonitor);
1.231 provos 668:
669: /* NEVERREACHED */
670: exit(0);
671: }
672:
1.242 mouring 673: close(pmonitor->m_sendfd);
1.231 provos 674:
675: /* Demote the private keys to public keys. */
676: demote_sensitive_data();
1.354 djm 677:
678: arc4random_stir();
1.356 djm 679: arc4random_buf(rnd, sizeof(rnd));
1.354 djm 680: RAND_seed(rnd, sizeof(rnd));
1.231 provos 681:
682: /* Drop privileges */
683: do_setusercontext(authctxt->pw);
684:
1.315 djm 685: skip:
1.231 provos 686: /* It is safe now to apply the key state */
1.242 mouring 687: monitor_apply_keystate(pmonitor);
1.312 markus 688:
689: /*
690: * Tell the packet layer that authentication was successful, since
691: * this information is not part of the key state.
692: */
693: packet_set_authenticated();
1.231 provos 694: }
695:
1.200 itojun 696: static char *
1.134 markus 697: list_hostkey_types(void)
698: {
1.223 markus 699: Buffer b;
1.281 jakob 700: const char *p;
701: char *ret;
1.134 markus 702: int i;
1.223 markus 703:
704: buffer_init(&b);
1.217 deraadt 705: for (i = 0; i < options.num_host_key_files; i++) {
1.134 markus 706: Key *key = sensitive_data.host_keys[i];
707: if (key == NULL)
708: continue;
1.214 deraadt 709: switch (key->type) {
1.134 markus 710: case KEY_RSA:
711: case KEY_DSA:
1.223 markus 712: if (buffer_len(&b) > 0)
713: buffer_append(&b, ",", 1);
714: p = key_ssh_name(key);
715: buffer_append(&b, p, strlen(p));
1.134 markus 716: break;
717: }
718: }
1.223 markus 719: buffer_append(&b, "\0", 1);
1.281 jakob 720: ret = xstrdup(buffer_ptr(&b));
1.223 markus 721: buffer_free(&b);
1.281 jakob 722: debug("list_hostkey_types: %s", ret);
723: return ret;
1.134 markus 724: }
725:
1.231 provos 726: Key *
1.134 markus 727: get_hostkey_by_type(int type)
728: {
729: int i;
1.250 deraadt 730:
1.217 deraadt 731: for (i = 0; i < options.num_host_key_files; i++) {
1.134 markus 732: Key *key = sensitive_data.host_keys[i];
733: if (key != NULL && key->type == type)
734: return key;
735: }
736: return NULL;
1.96 markus 737: }
738:
1.231 provos 739: Key *
740: get_hostkey_by_index(int ind)
741: {
742: if (ind < 0 || ind >= options.num_host_key_files)
743: return (NULL);
744: return (sensitive_data.host_keys[ind]);
745: }
746:
747: int
748: get_hostkey_index(Key *key)
749: {
750: int i;
1.250 deraadt 751:
1.231 provos 752: for (i = 0; i < options.num_host_key_files; i++) {
753: if (key == sensitive_data.host_keys[i])
754: return (i);
755: }
756: return (-1);
757: }
758:
1.124 markus 759: /*
760: * returns 1 if connection should be dropped, 0 otherwise.
761: * dropping starts at connection #max_startups_begin with a probability
762: * of (max_startups_rate/100). the probability increases linearly until
763: * all connections are dropped for startups > max_startups
764: */
1.200 itojun 765: static int
1.124 markus 766: drop_connection(int startups)
767: {
1.303 mickey 768: int p, r;
1.124 markus 769:
770: if (startups < options.max_startups_begin)
771: return 0;
772: if (startups >= options.max_startups)
773: return 1;
774: if (options.max_startups_rate == 100)
775: return 1;
776:
777: p = 100 - options.max_startups_rate;
778: p *= startups - options.max_startups_begin;
1.303 mickey 779: p /= options.max_startups - options.max_startups_begin;
1.124 markus 780: p += options.max_startups_rate;
1.356 djm 781: r = arc4random_uniform(100);
1.124 markus 782:
1.304 djm 783: debug("drop_connection: p %d, r %d", p, r);
1.124 markus 784: return (r < p) ? 1 : 0;
785: }
786:
1.215 markus 787: static void
788: usage(void)
789: {
1.290 markus 790: fprintf(stderr, "%s, %s\n",
1.280 markus 791: SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
1.289 markus 792: fprintf(stderr,
1.359 jmc 793: "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-f config_file]\n"
794: " [-g login_grace_time] [-h host_key_file] [-k key_gen_time]\n"
795: " [-o option] [-p port] [-u len]\n"
1.289 markus 796: );
1.215 markus 797: exit(1);
798: }
799:
1.294 djm 800: static void
801: send_rexec_state(int fd, Buffer *conf)
802: {
803: Buffer m;
804:
805: debug3("%s: entering fd = %d config len %d", __func__, fd,
806: buffer_len(conf));
807:
808: /*
809: * Protocol from reexec master to child:
810: * string configuration
811: * u_int ephemeral_key_follows
812: * bignum e (only if ephemeral_key_follows == 1)
813: * bignum n "
814: * bignum d "
815: * bignum iqmp "
816: * bignum p "
817: * bignum q "
818: */
819: buffer_init(&m);
820: buffer_put_cstring(&m, buffer_ptr(conf));
821:
1.298 deraadt 822: if (sensitive_data.server_key != NULL &&
1.294 djm 823: sensitive_data.server_key->type == KEY_RSA1) {
824: buffer_put_int(&m, 1);
825: buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
826: buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
827: buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
828: buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
829: buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
830: buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
831: } else
832: buffer_put_int(&m, 0);
833:
834: if (ssh_msg_send(fd, 0, &m) == -1)
835: fatal("%s: ssh_msg_send failed", __func__);
836:
837: buffer_free(&m);
838:
839: debug3("%s: done", __func__);
840: }
841:
842: static void
843: recv_rexec_state(int fd, Buffer *conf)
844: {
845: Buffer m;
846: char *cp;
847: u_int len;
848:
849: debug3("%s: entering fd = %d", __func__, fd);
850:
851: buffer_init(&m);
852:
853: if (ssh_msg_recv(fd, &m) == -1)
854: fatal("%s: ssh_msg_recv failed", __func__);
855: if (buffer_get_char(&m) != 0)
856: fatal("%s: rexec version mismatch", __func__);
857:
858: cp = buffer_get_string(&m, &len);
859: if (conf != NULL)
860: buffer_append(conf, cp, len + 1);
861: xfree(cp);
862:
863: if (buffer_get_int(&m)) {
864: if (sensitive_data.server_key != NULL)
865: key_free(sensitive_data.server_key);
866: sensitive_data.server_key = key_new_private(KEY_RSA1);
867: buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
868: buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
869: buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
870: buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
871: buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
872: buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
873: rsa_generate_additional_parameters(
874: sensitive_data.server_key->rsa);
875: }
876: buffer_free(&m);
877:
878: debug3("%s: done", __func__);
879: }
880:
1.345 djm 881: /* Accept a connection from inetd */
882: static void
883: server_accept_inetd(int *sock_in, int *sock_out)
884: {
885: int fd;
886:
887: startup_pipe = -1;
888: if (rexeced_flag) {
889: close(REEXEC_CONFIG_PASS_FD);
890: *sock_in = *sock_out = dup(STDIN_FILENO);
891: if (!debug_flag) {
892: startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
893: close(REEXEC_STARTUP_PIPE_FD);
894: }
895: } else {
896: *sock_in = dup(STDIN_FILENO);
897: *sock_out = dup(STDOUT_FILENO);
898: }
899: /*
900: * We intentionally do not close the descriptors 0, 1, and 2
901: * as our code for setting the descriptors won't work if
902: * ttyfd happens to be one of those.
903: */
904: if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
905: dup2(fd, STDIN_FILENO);
906: dup2(fd, STDOUT_FILENO);
907: if (fd > STDOUT_FILENO)
908: close(fd);
909: }
910: debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
911: }
912:
913: /*
914: * Listen for TCP connections
915: */
916: static void
917: server_listen(void)
918: {
919: int ret, listen_sock, on = 1;
920: struct addrinfo *ai;
921: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
922:
923: for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
924: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
925: continue;
926: if (num_listen_socks >= MAX_LISTEN_SOCKS)
927: fatal("Too many listen sockets. "
928: "Enlarge MAX_LISTEN_SOCKS");
929: if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
930: ntop, sizeof(ntop), strport, sizeof(strport),
931: NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
932: error("getnameinfo failed: %.100s",
1.352 dtucker 933: ssh_gai_strerror(ret));
1.345 djm 934: continue;
935: }
936: /* Create socket for listening. */
1.368 reyk 937: listen_sock = socket_rdomain(ai->ai_family, ai->ai_socktype,
938: ai->ai_protocol, options.rdomain);
1.345 djm 939: if (listen_sock < 0) {
940: /* kernel may not support ipv6 */
941: verbose("socket: %.100s", strerror(errno));
942: continue;
943: }
944: if (set_nonblock(listen_sock) == -1) {
945: close(listen_sock);
946: continue;
947: }
948: /*
949: * Set socket options.
950: * Allow local port reuse in TIME_WAIT.
951: */
952: if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
953: &on, sizeof(on)) == -1)
954: error("setsockopt SO_REUSEADDR: %s", strerror(errno));
955:
956: debug("Bind to port %s on %s.", strport, ntop);
957:
958: /* Bind the socket to the desired port. */
959: if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
960: error("Bind to port %s on %s failed: %.200s.",
961: strport, ntop, strerror(errno));
962: close(listen_sock);
963: continue;
964: }
965: listen_socks[num_listen_socks] = listen_sock;
966: num_listen_socks++;
967:
968: /* Start listening on the port. */
969: if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
970: fatal("listen on [%s]:%s: %.100s",
971: ntop, strport, strerror(errno));
972: logit("Server listening on %s port %s.", ntop, strport);
973: }
974: freeaddrinfo(options.listen_addrs);
975:
976: if (!num_listen_socks)
977: fatal("Cannot bind any address.");
978: }
979:
980: /*
981: * The main TCP accept loop. Note that, for the non-debug case, returns
982: * from this function are in a forked subprocess.
983: */
984: static void
985: server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
986: {
987: fd_set *fdset;
988: int i, j, ret, maxfd;
989: int key_used = 0, startups = 0;
990: int startup_p[2] = { -1 , -1 };
991: struct sockaddr_storage from;
992: socklen_t fromlen;
993: pid_t pid;
994:
995: /* setup fd set for accept */
996: fdset = NULL;
997: maxfd = 0;
998: for (i = 0; i < num_listen_socks; i++)
999: if (listen_socks[i] > maxfd)
1000: maxfd = listen_socks[i];
1001: /* pipes connected to unauthenticated childs */
1002: startup_pipes = xcalloc(options.max_startups, sizeof(int));
1003: for (i = 0; i < options.max_startups; i++)
1004: startup_pipes[i] = -1;
1005:
1006: /*
1007: * Stay listening for connections until the system crashes or
1008: * the daemon is killed with a signal.
1009: */
1010: for (;;) {
1011: if (received_sighup)
1012: sighup_restart();
1013: if (fdset != NULL)
1014: xfree(fdset);
1015: fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1016: sizeof(fd_mask));
1017:
1018: for (i = 0; i < num_listen_socks; i++)
1019: FD_SET(listen_socks[i], fdset);
1020: for (i = 0; i < options.max_startups; i++)
1021: if (startup_pipes[i] != -1)
1022: FD_SET(startup_pipes[i], fdset);
1023:
1024: /* Wait in select until there is a connection. */
1025: ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1026: if (ret < 0 && errno != EINTR)
1027: error("select: %.100s", strerror(errno));
1028: if (received_sigterm) {
1029: logit("Received signal %d; terminating.",
1030: (int) received_sigterm);
1031: close_listen_socks();
1032: unlink(options.pid_file);
1033: exit(255);
1034: }
1035: if (key_used && key_do_regen) {
1036: generate_ephemeral_server_key();
1037: key_used = 0;
1038: key_do_regen = 0;
1039: }
1040: if (ret < 0)
1041: continue;
1042:
1043: for (i = 0; i < options.max_startups; i++)
1044: if (startup_pipes[i] != -1 &&
1045: FD_ISSET(startup_pipes[i], fdset)) {
1046: /*
1047: * the read end of the pipe is ready
1048: * if the child has closed the pipe
1049: * after successful authentication
1050: * or if the child has died
1051: */
1052: close(startup_pipes[i]);
1053: startup_pipes[i] = -1;
1054: startups--;
1055: }
1056: for (i = 0; i < num_listen_socks; i++) {
1057: if (!FD_ISSET(listen_socks[i], fdset))
1058: continue;
1059: fromlen = sizeof(from);
1060: *newsock = accept(listen_socks[i],
1061: (struct sockaddr *)&from, &fromlen);
1062: if (*newsock < 0) {
1063: if (errno != EINTR && errno != EWOULDBLOCK)
1064: error("accept: %.100s", strerror(errno));
1065: continue;
1066: }
1067: if (unset_nonblock(*newsock) == -1) {
1068: close(*newsock);
1069: continue;
1070: }
1071: if (drop_connection(startups) == 1) {
1072: debug("drop connection #%d", startups);
1073: close(*newsock);
1074: continue;
1075: }
1076: if (pipe(startup_p) == -1) {
1077: close(*newsock);
1078: continue;
1079: }
1080:
1081: if (rexec_flag && socketpair(AF_UNIX,
1082: SOCK_STREAM, 0, config_s) == -1) {
1083: error("reexec socketpair: %s",
1084: strerror(errno));
1085: close(*newsock);
1086: close(startup_p[0]);
1087: close(startup_p[1]);
1088: continue;
1089: }
1090:
1091: for (j = 0; j < options.max_startups; j++)
1092: if (startup_pipes[j] == -1) {
1093: startup_pipes[j] = startup_p[0];
1094: if (maxfd < startup_p[0])
1095: maxfd = startup_p[0];
1096: startups++;
1097: break;
1098: }
1099:
1100: /*
1101: * Got connection. Fork a child to handle it, unless
1102: * we are in debugging mode.
1103: */
1104: if (debug_flag) {
1105: /*
1106: * In debugging mode. Close the listening
1107: * socket, and start processing the
1108: * connection without forking.
1109: */
1110: debug("Server will not fork when running in debugging mode.");
1111: close_listen_socks();
1112: *sock_in = *newsock;
1113: *sock_out = *newsock;
1114: close(startup_p[0]);
1115: close(startup_p[1]);
1116: startup_pipe = -1;
1117: pid = getpid();
1118: if (rexec_flag) {
1119: send_rexec_state(config_s[0],
1120: &cfg);
1121: close(config_s[0]);
1122: }
1123: break;
1124: }
1125:
1126: /*
1127: * Normal production daemon. Fork, and have
1128: * the child process the connection. The
1129: * parent continues listening.
1130: */
1131: if ((pid = fork()) == 0) {
1132: /*
1133: * Child. Close the listening and
1134: * max_startup sockets. Start using
1135: * the accepted socket. Reinitialize
1136: * logging (since our pid has changed).
1137: * We break out of the loop to handle
1138: * the connection.
1139: */
1140: startup_pipe = startup_p[1];
1141: close_startup_pipes();
1142: close_listen_socks();
1143: *sock_in = *newsock;
1144: *sock_out = *newsock;
1145: log_init(__progname,
1146: options.log_level,
1147: options.log_facility,
1148: log_stderr);
1149: if (rexec_flag)
1150: close(config_s[0]);
1151: break;
1152: }
1153:
1154: /* Parent. Stay in the loop. */
1155: if (pid < 0)
1156: error("fork: %.100s", strerror(errno));
1157: else
1158: debug("Forked child %ld.", (long)pid);
1159:
1160: close(startup_p[1]);
1161:
1162: if (rexec_flag) {
1163: send_rexec_state(config_s[0], &cfg);
1164: close(config_s[0]);
1165: close(config_s[1]);
1166: }
1167:
1168: /*
1169: * Mark that the key has been used (it
1170: * was "given" to the child).
1171: */
1172: if ((options.protocol & SSH_PROTO_1) &&
1173: key_used == 0) {
1174: /* Schedule server key regeneration alarm. */
1175: signal(SIGALRM, key_regeneration_alarm);
1176: alarm(options.key_regeneration_time);
1177: key_used = 1;
1178: }
1179:
1180: close(*newsock);
1181:
1182: /*
1183: * Ensure that our random state differs
1184: * from that of the child
1185: */
1186: arc4random_stir();
1187: }
1188:
1189: /* child process check (or debug mode) */
1190: if (num_listen_socks < 0)
1191: break;
1192: }
1193: }
1194:
1195:
1.65 deraadt 1196: /*
1197: * Main program for the daemon.
1198: */
1.2 provos 1199: int
1200: main(int ac, char **av)
1.1 deraadt 1201: {
1.64 markus 1202: extern char *optarg;
1203: extern int optind;
1.345 djm 1204: int opt, i, on = 1;
1.297 avsm 1205: int sock_in = -1, sock_out = -1, newsock = -1;
1.64 markus 1206: const char *remote_ip;
1.358 dtucker 1207: char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1.64 markus 1208: int remote_port;
1.358 dtucker 1209: char *line, *p, *cp;
1.345 djm 1210: int config_s[2] = { -1 , -1 };
1.364 markus 1211: u_int64_t ibytes, obytes;
1.362 dtucker 1212: mode_t new_umask;
1.278 markus 1213: Key *key;
1.230 provos 1214: Authctxt *authctxt;
1.64 markus 1215:
1.138 markus 1216: /* Save argv. */
1.64 markus 1217: saved_argv = av;
1.294 djm 1218: rexec_argc = ac;
1.313 djm 1219:
1220: /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1221: sanitise_stdfd();
1.64 markus 1222:
1223: /* Initialize configuration options to their default values. */
1224: initialize_server_options(&options);
1225:
1226: /* Parse command-line arguments. */
1.358 dtucker 1227: while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1.64 markus 1228: switch (opt) {
1.75 markus 1229: case '4':
1.305 djm 1230: options.address_family = AF_INET;
1.75 markus 1231: break;
1232: case '6':
1.305 djm 1233: options.address_family = AF_INET6;
1.75 markus 1234: break;
1.64 markus 1235: case 'f':
1236: config_file_name = optarg;
1237: break;
1238: case 'd':
1.273 markus 1239: if (debug_flag == 0) {
1.127 markus 1240: debug_flag = 1;
1241: options.log_level = SYSLOG_LEVEL_DEBUG1;
1.273 markus 1242: } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1.127 markus 1243: options.log_level++;
1.64 markus 1244: break;
1.135 markus 1245: case 'D':
1246: no_daemon_flag = 1;
1.192 lebel 1247: break;
1248: case 'e':
1249: log_stderr = 1;
1.135 markus 1250: break;
1.64 markus 1251: case 'i':
1252: inetd_flag = 1;
1253: break;
1.294 djm 1254: case 'r':
1255: rexec_flag = 0;
1256: break;
1257: case 'R':
1258: rexeced_flag = 1;
1259: inetd_flag = 1;
1260: break;
1.64 markus 1261: case 'Q':
1.158 markus 1262: /* ignored */
1.64 markus 1263: break;
1264: case 'q':
1265: options.log_level = SYSLOG_LEVEL_QUIET;
1266: break;
1267: case 'b':
1.327 deraadt 1268: options.server_key_bits = (int)strtonum(optarg, 256,
1269: 32768, NULL);
1.64 markus 1270: break;
1271: case 'p':
1.75 markus 1272: options.ports_from_cmdline = 1;
1.127 markus 1273: if (options.num_ports >= MAX_PORTS) {
1274: fprintf(stderr, "too many ports.\n");
1275: exit(1);
1276: }
1.193 stevesk 1277: options.ports[options.num_ports++] = a2port(optarg);
1.366 djm 1278: if (options.ports[options.num_ports-1] <= 0) {
1.193 stevesk 1279: fprintf(stderr, "Bad port number.\n");
1280: exit(1);
1281: }
1.64 markus 1282: break;
1283: case 'g':
1.197 stevesk 1284: if ((options.login_grace_time = convtime(optarg)) == -1) {
1285: fprintf(stderr, "Invalid login grace time.\n");
1286: exit(1);
1287: }
1.64 markus 1288: break;
1289: case 'k':
1.197 stevesk 1290: if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1291: fprintf(stderr, "Invalid key regeneration interval.\n");
1292: exit(1);
1293: }
1.64 markus 1294: break;
1295: case 'h':
1.134 markus 1296: if (options.num_host_key_files >= MAX_HOSTKEYS) {
1297: fprintf(stderr, "too many host keys.\n");
1298: exit(1);
1299: }
1300: options.host_key_files[options.num_host_key_files++] = optarg;
1.64 markus 1301: break;
1.203 stevesk 1302: case 't':
1303: test_flag = 1;
1304: break;
1.358 dtucker 1305: case 'T':
1306: test_flag = 2;
1307: break;
1308: case 'C':
1309: cp = optarg;
1310: while ((p = strsep(&cp, ",")) && *p != '\0') {
1311: if (strncmp(p, "addr=", 5) == 0)
1312: test_addr = xstrdup(p + 5);
1313: else if (strncmp(p, "host=", 5) == 0)
1314: test_host = xstrdup(p + 5);
1315: else if (strncmp(p, "user=", 5) == 0)
1316: test_user = xstrdup(p + 5);
1317: else {
1318: fprintf(stderr, "Invalid test "
1319: "mode specification %s\n", p);
1320: exit(1);
1321: }
1322: }
1323: break;
1.125 markus 1324: case 'u':
1.327 deraadt 1325: utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1.257 stevesk 1326: if (utmp_len > MAXHOSTNAMELEN) {
1327: fprintf(stderr, "Invalid utmp length.\n");
1328: exit(1);
1329: }
1.125 markus 1330: break;
1.215 markus 1331: case 'o':
1.283 markus 1332: line = xstrdup(optarg);
1333: if (process_server_config_line(&options, line,
1.337 dtucker 1334: "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1.217 deraadt 1335: exit(1);
1.283 markus 1336: xfree(line);
1.215 markus 1337: break;
1.64 markus 1338: case '?':
1339: default:
1.215 markus 1340: usage();
1341: break;
1.64 markus 1342: }
1343: }
1.294 djm 1344: if (rexeced_flag || inetd_flag)
1345: rexec_flag = 0;
1.355 mbalmer 1346: if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1.294 djm 1347: fatal("sshd re-exec requires execution with an absolute path");
1348: if (rexeced_flag)
1.296 djm 1349: closefrom(REEXEC_MIN_FREE_FD);
1350: else
1351: closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1.294 djm 1352:
1.180 markus 1353: SSLeay_add_all_algorithms();
1.64 markus 1354:
1.75 markus 1355: /*
1356: * Force logging to stderr until we have loaded the private host
1357: * key (unless started from inetd)
1358: */
1.138 markus 1359: log_init(__progname,
1.224 markus 1360: options.log_level == SYSLOG_LEVEL_NOT_SET ?
1361: SYSLOG_LEVEL_INFO : options.log_level,
1362: options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1363: SYSLOG_FACILITY_AUTH : options.log_facility,
1.261 markus 1364: log_stderr || !inetd_flag);
1.75 markus 1365:
1.294 djm 1366: sensitive_data.server_key = NULL;
1367: sensitive_data.ssh1_host_key = NULL;
1368: sensitive_data.have_ssh1_key = 0;
1369: sensitive_data.have_ssh2_key = 0;
1370:
1.358 dtucker 1371: /*
1372: * If we're doing an extended config test, make sure we have all of
1373: * the parameters we need. If we're not doing an extended test,
1374: * do not silently ignore connection test params.
1375: */
1.361 dtucker 1376: if (test_flag >= 2 &&
1377: (test_user != NULL || test_host != NULL || test_addr != NULL)
1.358 dtucker 1378: && (test_user == NULL || test_host == NULL || test_addr == NULL))
1379: fatal("user, host and addr are all required when testing "
1380: "Match configs");
1381: if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1382: test_addr != NULL))
1383: fatal("Config test connection parameter (-C) provided without "
1384: "test mode (-T)");
1385:
1.294 djm 1386: /* Fetch our configuration */
1387: buffer_init(&cfg);
1388: if (rexeced_flag)
1.296 djm 1389: recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1.294 djm 1390: else
1391: load_server_config(config_file_name, &cfg);
1392:
1.337 dtucker 1393: parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1394: &cfg, NULL, NULL, NULL);
1.64 markus 1395:
1396: /* Fill in default values for those options not explicitly set. */
1397: fill_default_server_options(&options);
1.350 dtucker 1398:
1399: /* challenge-response is implemented via keyboard interactive */
1400: if (options.challenge_response_authentication)
1401: options.kbd_interactive_authentication = 1;
1.305 djm 1402:
1.368 reyk 1403: /* set default channel AF and routing domain */
1.305 djm 1404: channel_set_af(options.address_family);
1.368 reyk 1405: channel_set_rdomain(options.rdomain);
1.64 markus 1406:
1407: /* Check that there are no remaining arguments. */
1408: if (optind < ac) {
1409: fprintf(stderr, "Extra argument %s.\n", av[optind]);
1410: exit(1);
1411: }
1412:
1413: debug("sshd version %.100s", SSH_VERSION);
1414:
1.134 markus 1415: /* load private host keys */
1.329 djm 1416: sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1.255 deraadt 1417: sizeof(Key *));
1.217 deraadt 1418: for (i = 0; i < options.num_host_key_files; i++)
1.141 markus 1419: sensitive_data.host_keys[i] = NULL;
1.134 markus 1420:
1.217 deraadt 1421: for (i = 0; i < options.num_host_key_files; i++) {
1.179 markus 1422: key = key_load_private(options.host_key_files[i], "", NULL);
1423: sensitive_data.host_keys[i] = key;
1.134 markus 1424: if (key == NULL) {
1.195 markus 1425: error("Could not load host key: %s",
1426: options.host_key_files[i]);
1.179 markus 1427: sensitive_data.host_keys[i] = NULL;
1.134 markus 1428: continue;
1429: }
1.214 deraadt 1430: switch (key->type) {
1.134 markus 1431: case KEY_RSA1:
1432: sensitive_data.ssh1_host_key = key;
1433: sensitive_data.have_ssh1_key = 1;
1434: break;
1435: case KEY_RSA:
1436: case KEY_DSA:
1437: sensitive_data.have_ssh2_key = 1;
1438: break;
1439: }
1.179 markus 1440: debug("private host key: #%d type %d %s", i, key->type,
1441: key_type(key));
1.134 markus 1442: }
1443: if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1.264 itojun 1444: logit("Disabling protocol version 1. Could not load host key");
1.108 markus 1445: options.protocol &= ~SSH_PROTO_1;
1446: }
1.134 markus 1447: if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1.264 itojun 1448: logit("Disabling protocol version 2. Could not load host key");
1.134 markus 1449: options.protocol &= ~SSH_PROTO_2;
1.108 markus 1450: }
1.162 stevesk 1451: if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1.264 itojun 1452: logit("sshd: no hostkeys available -- exiting.");
1.64 markus 1453: exit(1);
1454: }
1455:
1.108 markus 1456: /* Check certain values for sanity. */
1457: if (options.protocol & SSH_PROTO_1) {
1458: if (options.server_key_bits < 512 ||
1459: options.server_key_bits > 32768) {
1460: fprintf(stderr, "Bad server key size.\n");
1461: exit(1);
1462: }
1463: /*
1464: * Check that server and host key lengths differ sufficiently. This
1465: * is necessary to make double encryption work with rsaref. Oh, I
1466: * hate software patents. I dont know if this can go? Niels
1467: */
1468: if (options.server_key_bits >
1.250 deraadt 1469: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1470: SSH_KEY_BITS_RESERVED && options.server_key_bits <
1471: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1472: SSH_KEY_BITS_RESERVED) {
1.108 markus 1473: options.server_key_bits =
1.250 deraadt 1474: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1475: SSH_KEY_BITS_RESERVED;
1.108 markus 1476: debug("Forcing server key to %d bits to make it differ from host key.",
1477: options.server_key_bits);
1478: }
1.244 markus 1479: }
1480:
1481: if (use_privsep) {
1482: struct stat st;
1483:
1.327 deraadt 1484: if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1.244 markus 1485: fatal("Privilege separation user %s does not exist",
1486: SSH_PRIVSEP_USER);
1487: if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1488: (S_ISDIR(st.st_mode) == 0))
1489: fatal("Missing privilege separation directory: %s",
1.247 stevesk 1490: _PATH_PRIVSEP_CHROOT_DIR);
1491: if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1.262 markus 1492: fatal("%s must be owned by root and not group or "
1493: "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1.358 dtucker 1494: }
1495:
1496: if (test_flag > 1) {
1497: if (test_user != NULL && test_addr != NULL && test_host != NULL)
1498: parse_server_match_config(&options, test_user,
1499: test_host, test_addr);
1500: dump_config(&options);
1.108 markus 1501: }
1.203 stevesk 1502:
1503: /* Configuration looks good, so exit if in test mode. */
1504: if (test_flag)
1505: exit(0);
1.108 markus 1506:
1.294 djm 1507: if (rexec_flag) {
1.329 djm 1508: rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1.294 djm 1509: for (i = 0; i < rexec_argc; i++) {
1510: debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1511: rexec_argv[i] = saved_argv[i];
1512: }
1513: rexec_argv[rexec_argc] = "-R";
1514: rexec_argv[rexec_argc + 1] = NULL;
1515: }
1.362 dtucker 1516:
1517: /* Ensure that umask disallows at least group and world write */
1518: new_umask = umask(0077) | 0022;
1519: (void) umask(new_umask);
1.294 djm 1520:
1.108 markus 1521: /* Initialize the log (it is reinitialized below in case we forked). */
1.306 dtucker 1522: if (debug_flag && (!inetd_flag || rexeced_flag))
1.64 markus 1523: log_stderr = 1;
1.138 markus 1524: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.64 markus 1525:
1.108 markus 1526: /*
1527: * If not in debugging mode, and not started from inetd, disconnect
1528: * from the controlling terminal, and fork. The original process
1529: * exits.
1530: */
1.135 markus 1531: if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1.64 markus 1532: int fd;
1.345 djm 1533:
1.64 markus 1534: if (daemon(0, 0) < 0)
1535: fatal("daemon() failed: %.200s", strerror(errno));
1536:
1537: /* Disconnect from the controlling tty. */
1.165 itojun 1538: fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1.64 markus 1539: if (fd >= 0) {
1540: (void) ioctl(fd, TIOCNOTTY, NULL);
1541: close(fd);
1542: }
1543: }
1544: /* Reinitialize the log (because of the fork above). */
1.138 markus 1545: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.64 markus 1546:
1547: /* Initialize the random number generator. */
1548: arc4random_stir();
1549:
1550: /* Chdir to the root directory so that the current disk can be
1551: unmounted if desired. */
1552: chdir("/");
1.217 deraadt 1553:
1.178 markus 1554: /* ignore SIGPIPE */
1555: signal(SIGPIPE, SIG_IGN);
1.64 markus 1556:
1.345 djm 1557: /* Get a connection, either from inetd or a listening TCP socket */
1.64 markus 1558: if (inetd_flag) {
1.345 djm 1559: server_accept_inetd(&sock_in, &sock_out);
1.64 markus 1560: } else {
1.345 djm 1561: server_listen();
1.75 markus 1562:
1.201 markus 1563: if (options.protocol & SSH_PROTO_1)
1564: generate_ephemeral_server_key();
1565:
1566: signal(SIGHUP, sighup_handler);
1.345 djm 1567: signal(SIGCHLD, main_sigchld_handler);
1.201 markus 1568: signal(SIGTERM, sigterm_handler);
1569: signal(SIGQUIT, sigterm_handler);
1570:
1.345 djm 1571: /*
1572: * Write out the pid file after the sigterm handler
1573: * is setup and the listen sockets are bound
1574: */
1575: if (!debug_flag) {
1576: FILE *f = fopen(options.pid_file, "w");
1.201 markus 1577:
1.270 djm 1578: if (f == NULL) {
1579: error("Couldn't create pid file \"%s\": %s",
1580: options.pid_file, strerror(errno));
1581: } else {
1.245 mpech 1582: fprintf(f, "%ld\n", (long) getpid());
1.64 markus 1583: fclose(f);
1584: }
1585: }
1586:
1.345 djm 1587: /* Accept a connection and return in a forked child */
1588: server_accept_loop(&sock_in, &sock_out,
1589: &newsock, config_s);
1.1 deraadt 1590: }
1591:
1.64 markus 1592: /* This is the child processing a new connection. */
1.288 markus 1593: setproctitle("%s", "[accepted]");
1.294 djm 1594:
1.300 markus 1595: /*
1596: * Create a new session and process group since the 4.4BSD
1597: * setlogin() affects the entire process group. We don't
1598: * want the child to be able to affect the parent.
1599: */
1600: if (!debug_flag && !inetd_flag && setsid() < 0)
1601: error("setsid: %.100s", strerror(errno));
1602:
1.294 djm 1603: if (rexec_flag) {
1604: int fd;
1605:
1.296 djm 1606: debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1607: sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1.294 djm 1608: dup2(newsock, STDIN_FILENO);
1609: dup2(STDIN_FILENO, STDOUT_FILENO);
1610: if (startup_pipe == -1)
1.296 djm 1611: close(REEXEC_STARTUP_PIPE_FD);
1.294 djm 1612: else
1.296 djm 1613: dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1.294 djm 1614:
1.296 djm 1615: dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1.294 djm 1616: close(config_s[1]);
1.301 dtucker 1617: if (startup_pipe != -1)
1618: close(startup_pipe);
1.296 djm 1619:
1.294 djm 1620: execv(rexec_argv[0], rexec_argv);
1621:
1622: /* Reexec has failed, fall back and continue */
1623: error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1.296 djm 1624: recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1.294 djm 1625: log_init(__progname, options.log_level,
1626: options.log_facility, log_stderr);
1627:
1628: /* Clean up fds */
1.296 djm 1629: startup_pipe = REEXEC_STARTUP_PIPE_FD;
1.294 djm 1630: close(config_s[1]);
1.296 djm 1631: close(REEXEC_CONFIG_PASS_FD);
1632: newsock = sock_out = sock_in = dup(STDIN_FILENO);
1.294 djm 1633: if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1634: dup2(fd, STDIN_FILENO);
1635: dup2(fd, STDOUT_FILENO);
1636: if (fd > STDERR_FILENO)
1637: close(fd);
1638: }
1.296 djm 1639: debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1640: sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1.294 djm 1641: }
1.64 markus 1642:
1.66 markus 1643: /*
1644: * Disable the key regeneration alarm. We will not regenerate the
1645: * key since we are no longer in a position to give it to anyone. We
1646: * will not restart on SIGHUP since it no longer makes sense.
1647: */
1.64 markus 1648: alarm(0);
1649: signal(SIGALRM, SIG_DFL);
1650: signal(SIGHUP, SIG_DFL);
1651: signal(SIGTERM, SIG_DFL);
1652: signal(SIGQUIT, SIG_DFL);
1653: signal(SIGCHLD, SIG_DFL);
1.150 markus 1654:
1.66 markus 1655: /*
1656: * Register our connection. This turns encryption off because we do
1657: * not have a key.
1658: */
1.64 markus 1659: packet_set_connection(sock_in, sock_out);
1.312 markus 1660: packet_set_server();
1.309 djm 1661:
1662: /* Set SO_KEEPALIVE if requested. */
1663: if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1664: setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1665: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.1 deraadt 1666:
1.310 markus 1667: if ((remote_port = get_remote_port()) < 0) {
1668: debug("get_remote_port failed");
1669: cleanup_exit(255);
1670: }
1.316 dtucker 1671:
1672: /*
1673: * We use get_canonical_hostname with usedns = 0 instead of
1674: * get_remote_ipaddr here so IP options will be checked.
1675: */
1.331 markus 1676: (void) get_canonical_hostname(0);
1677: /*
1678: * The rest of the code depends on the fact that
1679: * get_remote_ipaddr() caches the remote ip, even if
1680: * the socket goes away.
1681: */
1682: remote_ip = get_remote_ipaddr();
1.52 markus 1683:
1.209 markus 1684: #ifdef LIBWRAP
1.64 markus 1685: /* Check whether logins are denied from this host. */
1.295 djm 1686: if (packet_connection_is_on_socket()) {
1.64 markus 1687: struct request_info req;
1.37 dugsong 1688:
1.204 camield 1689: request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1.64 markus 1690: fromhost(&req);
1.37 dugsong 1691:
1.64 markus 1692: if (!hosts_access(&req)) {
1.209 markus 1693: debug("Connection refused by tcp wrapper");
1.182 markus 1694: refuse(&req);
1.209 markus 1695: /* NOTREACHED */
1696: fatal("libwrap refuse returns");
1.64 markus 1697: }
1698: }
1.75 markus 1699: #endif /* LIBWRAP */
1.209 markus 1700:
1.64 markus 1701: /* Log the connection. */
1702: verbose("Connection from %.500s port %d", remote_ip, remote_port);
1.1 deraadt 1703:
1.66 markus 1704: /*
1.317 djm 1705: * We don't want to listen forever unless the other side
1.66 markus 1706: * successfully authenticates itself. So we set up an alarm which is
1707: * cleared after successful authentication. A limit of zero
1.317 djm 1708: * indicates no limit. Note that we don't set the alarm in debugging
1.66 markus 1709: * mode; it is just annoying to have the server exit just when you
1710: * are about to discover the bug.
1711: */
1.64 markus 1712: signal(SIGALRM, grace_alarm_handler);
1713: if (!debug_flag)
1714: alarm(options.login_grace_time);
1715:
1.96 markus 1716: sshd_exchange_identification(sock_in, sock_out);
1.353 dtucker 1717:
1718: /* In inetd mode, generate ephemeral key only for proto 1 connections */
1719: if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1720: generate_ephemeral_server_key();
1.275 markus 1721:
1.64 markus 1722: packet_set_nonblocking();
1.1 deraadt 1723:
1.278 markus 1724: /* allocate authentication context */
1.329 djm 1725: authctxt = xcalloc(1, sizeof(*authctxt));
1.278 markus 1726:
1727: /* XXX global for cleanup, access from other modules */
1728: the_authctxt = authctxt;
1729:
1.307 otto 1730: /* prepare buffer to collect messages to display to user after login */
1731: buffer_init(&loginmsg);
1732:
1.237 markus 1733: if (use_privsep)
1.278 markus 1734: if (privsep_preauth(authctxt) == 1)
1.237 markus 1735: goto authenticated;
1.231 provos 1736:
1.77 markus 1737: /* perform the key exchange */
1738: /* authenticate user and start session */
1.98 markus 1739: if (compat20) {
1740: do_ssh2_kex();
1.278 markus 1741: do_authentication2(authctxt);
1.98 markus 1742: } else {
1743: do_ssh1_kex();
1.278 markus 1744: do_authentication(authctxt);
1.98 markus 1745: }
1.237 markus 1746: /*
1747: * If we use privilege separation, the unprivileged child transfers
1748: * the current keystate and exits
1749: */
1750: if (use_privsep) {
1.242 mouring 1751: mm_send_keystate(pmonitor);
1.231 provos 1752: exit(0);
1.237 markus 1753: }
1.231 provos 1754:
1755: authenticated:
1.318 djm 1756: /*
1757: * Cancel the alarm we set to limit the time taken for
1758: * authentication.
1759: */
1760: alarm(0);
1761: signal(SIGALRM, SIG_DFL);
1.347 markus 1762: authctxt->authenticated = 1;
1.318 djm 1763: if (startup_pipe != -1) {
1764: close(startup_pipe);
1765: startup_pipe = -1;
1766: }
1767:
1.234 markus 1768: /*
1.231 provos 1769: * In privilege separation, we fork another child and prepare
1770: * file descriptor passing.
1771: */
1772: if (use_privsep) {
1.237 markus 1773: privsep_postauth(authctxt);
1774: /* the monitor process [priv] will not return */
1.231 provos 1775: if (!compat20)
1776: destroy_sensitive_data();
1777: }
1.360 dtucker 1778:
1779: packet_set_timeout(options.client_alive_interval,
1780: options.client_alive_count_max);
1.230 provos 1781:
1.278 markus 1782: /* Start session. */
1.230 provos 1783: do_authenticated(authctxt);
1784:
1.64 markus 1785: /* The connection has been terminated. */
1.364 markus 1786: packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
1787: packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
1788: verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes);
1789:
1790: verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
1.64 markus 1791: packet_close();
1.231 provos 1792:
1793: if (use_privsep)
1794: mm_terminate();
1795:
1.64 markus 1796: exit(0);
1.1 deraadt 1797: }
1798:
1.65 deraadt 1799: /*
1.229 markus 1800: * Decrypt session_key_int using our private server key and private host key
1801: * (key with larger modulus first).
1802: */
1.231 provos 1803: int
1.229 markus 1804: ssh1_session_key(BIGNUM *session_key_int)
1805: {
1806: int rsafail = 0;
1807:
1.327 deraadt 1808: if (BN_cmp(sensitive_data.server_key->rsa->n,
1809: sensitive_data.ssh1_host_key->rsa->n) > 0) {
1.229 markus 1810: /* Server key has bigger modulus. */
1811: if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1.327 deraadt 1812: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1813: SSH_KEY_BITS_RESERVED) {
1814: fatal("do_connection: %s: "
1815: "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1.229 markus 1816: get_remote_ipaddr(),
1817: BN_num_bits(sensitive_data.server_key->rsa->n),
1818: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1819: SSH_KEY_BITS_RESERVED);
1820: }
1821: if (rsa_private_decrypt(session_key_int, session_key_int,
1822: sensitive_data.server_key->rsa) <= 0)
1823: rsafail++;
1824: if (rsa_private_decrypt(session_key_int, session_key_int,
1825: sensitive_data.ssh1_host_key->rsa) <= 0)
1826: rsafail++;
1827: } else {
1828: /* Host key has bigger modulus (or they are equal). */
1829: if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1.327 deraadt 1830: BN_num_bits(sensitive_data.server_key->rsa->n) +
1831: SSH_KEY_BITS_RESERVED) {
1832: fatal("do_connection: %s: "
1833: "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1.229 markus 1834: get_remote_ipaddr(),
1835: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1836: BN_num_bits(sensitive_data.server_key->rsa->n),
1837: SSH_KEY_BITS_RESERVED);
1838: }
1839: if (rsa_private_decrypt(session_key_int, session_key_int,
1840: sensitive_data.ssh1_host_key->rsa) < 0)
1841: rsafail++;
1842: if (rsa_private_decrypt(session_key_int, session_key_int,
1843: sensitive_data.server_key->rsa) < 0)
1844: rsafail++;
1845: }
1846: return (rsafail);
1847: }
1848: /*
1.77 markus 1849: * SSH1 key exchange
1.65 deraadt 1850: */
1.200 itojun 1851: static void
1.142 markus 1852: do_ssh1_kex(void)
1.1 deraadt 1853: {
1.64 markus 1854: int i, len;
1.159 markus 1855: int rsafail = 0;
1.64 markus 1856: BIGNUM *session_key_int;
1.140 markus 1857: u_char session_key[SSH_SESSION_KEY_LENGTH];
1858: u_char cookie[8];
1859: u_int cipher_type, auth_mask, protocol_flags;
1.64 markus 1860:
1.66 markus 1861: /*
1862: * Generate check bytes that the client must send back in the user
1863: * packet in order for it to be accepted; this is used to defy ip
1864: * spoofing attacks. Note that this only works against somebody
1865: * doing IP spoofing from a remote machine; any machine on the local
1866: * network can still see outgoing packets and catch the random
1867: * cookie. This only affects rhosts authentication, and this is one
1868: * of the reasons why it is inherently insecure.
1869: */
1.356 djm 1870: arc4random_buf(cookie, sizeof(cookie));
1.64 markus 1871:
1.66 markus 1872: /*
1873: * Send our public key. We include in the packet 64 bits of random
1874: * data that must be matched in the reply in order to prevent IP
1875: * spoofing.
1876: */
1.64 markus 1877: packet_start(SSH_SMSG_PUBLIC_KEY);
1878: for (i = 0; i < 8; i++)
1.77 markus 1879: packet_put_char(cookie[i]);
1.64 markus 1880:
1881: /* Store our public server RSA key. */
1.134 markus 1882: packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1883: packet_put_bignum(sensitive_data.server_key->rsa->e);
1884: packet_put_bignum(sensitive_data.server_key->rsa->n);
1.64 markus 1885:
1886: /* Store our public host RSA key. */
1.134 markus 1887: packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1888: packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1889: packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1.64 markus 1890:
1891: /* Put protocol flags. */
1892: packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1893:
1894: /* Declare which ciphers we support. */
1.131 markus 1895: packet_put_int(cipher_mask_ssh1(0));
1.64 markus 1896:
1897: /* Declare supported authentication types. */
1898: auth_mask = 0;
1899: if (options.rhosts_rsa_authentication)
1900: auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1901: if (options.rsa_authentication)
1902: auth_mask |= 1 << SSH_AUTH_RSA;
1.196 markus 1903: if (options.challenge_response_authentication == 1)
1.64 markus 1904: auth_mask |= 1 << SSH_AUTH_TIS;
1905: if (options.password_authentication)
1906: auth_mask |= 1 << SSH_AUTH_PASSWORD;
1907: packet_put_int(auth_mask);
1908:
1909: /* Send the packet and wait for it to be sent. */
1910: packet_send();
1911: packet_write_wait();
1912:
1.134 markus 1913: debug("Sent %d bit server key and %d bit host key.",
1914: BN_num_bits(sensitive_data.server_key->rsa->n),
1915: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1.64 markus 1916:
1917: /* Read clients reply (cipher type and session key). */
1.222 markus 1918: packet_read_expect(SSH_CMSG_SESSION_KEY);
1.64 markus 1919:
1.69 markus 1920: /* Get cipher type and check whether we accept this. */
1.64 markus 1921: cipher_type = packet_get_char();
1.69 markus 1922:
1.131 markus 1923: if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1.69 markus 1924: packet_disconnect("Warning: client selects unsupported cipher.");
1.64 markus 1925:
1926: /* Get check bytes from the packet. These must match those we
1927: sent earlier with the public key packet. */
1928: for (i = 0; i < 8; i++)
1.77 markus 1929: if (cookie[i] != packet_get_char())
1.64 markus 1930: packet_disconnect("IP Spoofing check bytes do not match.");
1931:
1932: debug("Encryption type: %.200s", cipher_name(cipher_type));
1933:
1934: /* Get the encrypted integer. */
1.218 markus 1935: if ((session_key_int = BN_new()) == NULL)
1936: fatal("do_ssh1_kex: BN_new failed");
1.221 markus 1937: packet_get_bignum(session_key_int);
1.64 markus 1938:
1939: protocol_flags = packet_get_int();
1940: packet_set_protocol_flags(protocol_flags);
1.220 markus 1941: packet_check_eom();
1.64 markus 1942:
1.229 markus 1943: /* Decrypt session_key_int using host/server keys */
1.231 provos 1944: rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1945:
1.66 markus 1946: /*
1947: * Extract session key from the decrypted integer. The key is in the
1948: * least significant 256 bits of the integer; the first byte of the
1949: * key is in the highest bits.
1950: */
1.159 markus 1951: if (!rsafail) {
1.348 markus 1952: (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1.159 markus 1953: len = BN_num_bytes(session_key_int);
1.311 djm 1954: if (len < 0 || (u_int)len > sizeof(session_key)) {
1.348 markus 1955: error("do_ssh1_kex: bad session key len from %s: "
1.165 itojun 1956: "session_key_int %d > sizeof(session_key) %lu",
1957: get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1.159 markus 1958: rsafail++;
1959: } else {
1960: memset(session_key, 0, sizeof(session_key));
1961: BN_bn2bin(session_key_int,
1962: session_key + sizeof(session_key) - len);
1.169 markus 1963:
1.291 djm 1964: derive_ssh1_session_id(
1.298 deraadt 1965: sensitive_data.ssh1_host_key->rsa->n,
1.291 djm 1966: sensitive_data.server_key->rsa->n,
1967: cookie, session_id);
1.169 markus 1968: /*
1969: * Xor the first 16 bytes of the session key with the
1970: * session id.
1971: */
1972: for (i = 0; i < 16; i++)
1973: session_key[i] ^= session_id[i];
1.159 markus 1974: }
1975: }
1976: if (rsafail) {
1.169 markus 1977: int bytes = BN_num_bytes(session_key_int);
1.227 stevesk 1978: u_char *buf = xmalloc(bytes);
1.169 markus 1979: MD5_CTX md;
1980:
1.264 itojun 1981: logit("do_connection: generating a fake encryption key");
1.169 markus 1982: BN_bn2bin(session_key_int, buf);
1983: MD5_Init(&md);
1984: MD5_Update(&md, buf, bytes);
1985: MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1986: MD5_Final(session_key, &md);
1987: MD5_Init(&md);
1988: MD5_Update(&md, session_key, 16);
1989: MD5_Update(&md, buf, bytes);
1990: MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1991: MD5_Final(session_key + 16, &md);
1992: memset(buf, 0, bytes);
1993: xfree(buf);
1.170 markus 1994: for (i = 0; i < 16; i++)
1995: session_id[i] = session_key[i] ^ session_key[i + 16];
1.159 markus 1996: }
1.231 provos 1997: /* Destroy the private and public keys. No longer. */
1.169 markus 1998: destroy_sensitive_data();
1999:
1.231 provos 2000: if (use_privsep)
2001: mm_ssh1_session_id(session_id);
2002:
1.77 markus 2003: /* Destroy the decrypted integer. It is no longer needed. */
2004: BN_clear_free(session_key_int);
1.64 markus 2005:
2006: /* Set the session key. From this on all communications will be encrypted. */
2007: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2008:
2009: /* Destroy our copy of the session key. It is no longer needed. */
2010: memset(session_key, 0, sizeof(session_key));
2011:
2012: debug("Received session key; encryption turned on.");
2013:
1.243 deraadt 2014: /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1.64 markus 2015: packet_start(SSH_SMSG_SUCCESS);
2016: packet_send();
2017: packet_write_wait();
1.98 markus 2018: }
2019:
2020: /*
2021: * SSH2 key exchange: diffie-hellman-group1-sha1
2022: */
1.200 itojun 2023: static void
1.142 markus 2024: do_ssh2_kex(void)
1.98 markus 2025: {
2026: Kex *kex;
1.102 markus 2027:
2028: if (options.ciphers != NULL) {
1.105 markus 2029: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1.102 markus 2030: myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1.166 markus 2031: }
1.184 stevesk 2032: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2033: compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2034: myproposal[PROPOSAL_ENC_ALGS_STOC] =
2035: compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2036:
1.166 markus 2037: if (options.macs != NULL) {
2038: myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2039: myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1.246 markus 2040: }
1.312 markus 2041: if (options.compression == COMP_NONE) {
1.246 markus 2042: myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2043: myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1.312 markus 2044: } else if (options.compression == COMP_DELAYED) {
2045: myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2046: myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
1.102 markus 2047: }
1.327 deraadt 2048:
1.134 markus 2049: myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2050:
1.189 markus 2051: /* start key exchange */
1.188 markus 2052: kex = kex_setup(myproposal);
1.263 markus 2053: kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
1.292 djm 2054: kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
1.263 markus 2055: kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1.324 djm 2056: kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
1.186 markus 2057: kex->server = 1;
2058: kex->client_version_string=client_version_string;
2059: kex->server_version_string=server_version_string;
2060: kex->load_host_key=&get_hostkey_by_type;
1.231 provos 2061: kex->host_key_index=&get_hostkey_index;
1.129 provos 2062:
1.189 markus 2063: xxx_kex = kex;
2064:
1.190 markus 2065: dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
1.187 markus 2066:
2067: session_id2 = kex->session_id;
2068: session_id2_len = kex->session_id_len;
1.129 provos 2069:
2070: #ifdef DEBUG_KEXDH
2071: /* send 1st encrypted/maced/compressed message */
2072: packet_start(SSH2_MSG_IGNORE);
2073: packet_put_cstring("markus");
2074: packet_send();
2075: packet_write_wait();
2076: #endif
1.186 markus 2077: debug("KEX done");
1.278 markus 2078: }
2079:
2080: /* server specific fatal cleanup */
2081: void
2082: cleanup_exit(int i)
2083: {
2084: if (the_authctxt)
2085: do_cleanup(the_authctxt);
2086: _exit(i);
1.1 deraadt 2087: }
![[BACK]](/icons/back.gif){kind=icon}
Return to sshd.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh