Annotation of src/usr.bin/ssh/sshd.c, Revision 1.364
1.364 ! markus 1: /* $OpenBSD: sshd.c,v 1.363 2008/07/01 07:24:22 dtucker 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"
104: #include "monitor_fdpass.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 */
1.64 markus 292: execv(saved_argv[0], saved_argv);
1.264 itojun 293: logit("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0],
1.250 deraadt 294: strerror(errno));
1.64 markus 295: exit(1);
1.1 deraadt 296: }
297:
1.65 deraadt 298: /*
299: * Generic signal handler for terminating signals in the master daemon.
300: */
1.327 deraadt 301: /*ARGSUSED*/
1.200 itojun 302: static void
1.64 markus 303: sigterm_handler(int sig)
1.1 deraadt 304: {
1.199 markus 305: received_sigterm = sig;
1.1 deraadt 306: }
307:
1.65 deraadt 308: /*
309: * SIGCHLD handler. This is called whenever a child dies. This will then
1.199 markus 310: * reap any zombies left by exited children.
1.65 deraadt 311: */
1.327 deraadt 312: /*ARGSUSED*/
1.200 itojun 313: static void
1.64 markus 314: main_sigchld_handler(int sig)
1.1 deraadt 315: {
1.250 deraadt 316: int save_errno = errno;
1.239 markus 317: pid_t pid;
1.64 markus 318: int status;
1.60 deraadt 319:
1.239 markus 320: while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
321: (pid < 0 && errno == EINTR))
1.64 markus 322: ;
1.60 deraadt 323:
1.64 markus 324: signal(SIGCHLD, main_sigchld_handler);
325: errno = save_errno;
1.1 deraadt 326: }
327:
1.65 deraadt 328: /*
329: * Signal handler for the alarm after the login grace period has expired.
330: */
1.327 deraadt 331: /*ARGSUSED*/
1.200 itojun 332: static void
1.64 markus 333: grace_alarm_handler(int sig)
1.1 deraadt 334: {
1.285 dtucker 335: if (use_privsep && pmonitor != NULL && pmonitor->m_pid > 0)
336: kill(pmonitor->m_pid, SIGALRM);
337:
1.64 markus 338: /* Log error and exit. */
1.346 deraadt 339: sigdie("Timeout before authentication for %s", get_remote_ipaddr());
1.62 markus 340: }
341:
1.65 deraadt 342: /*
343: * Signal handler for the key regeneration alarm. Note that this
344: * alarm only occurs in the daemon waiting for connections, and it does not
345: * do anything with the private key or random state before forking.
346: * Thus there should be no concurrency control/asynchronous execution
347: * problems.
348: */
1.200 itojun 349: static void
1.174 deraadt 350: generate_ephemeral_server_key(void)
1.134 markus 351: {
1.191 markus 352: verbose("Generating %s%d bit RSA key.",
1.185 djm 353: sensitive_data.server_key ? "new " : "", options.server_key_bits);
1.134 markus 354: if (sensitive_data.server_key != NULL)
355: key_free(sensitive_data.server_key);
1.191 markus 356: sensitive_data.server_key = key_generate(KEY_RSA1,
1.185 djm 357: options.server_key_bits);
358: verbose("RSA key generation complete.");
1.169 markus 359:
1.356 djm 360: arc4random_buf(sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1.134 markus 361: arc4random_stir();
362: }
1.147 deraadt 363:
1.327 deraadt 364: /*ARGSUSED*/
1.200 itojun 365: static void
1.64 markus 366: key_regeneration_alarm(int sig)
1.1 deraadt 367: {
1.64 markus 368: int save_errno = errno;
1.250 deraadt 369:
1.151 markus 370: signal(SIGALRM, SIG_DFL);
1.64 markus 371: errno = save_errno;
1.151 markus 372: key_do_regen = 1;
1.98 markus 373: }
374:
1.200 itojun 375: static void
1.96 markus 376: sshd_exchange_identification(int sock_in, int sock_out)
377: {
1.311 djm 378: u_int i;
379: int mismatch;
1.96 markus 380: int remote_major, remote_minor;
1.102 markus 381: int major, minor;
1.363 dtucker 382: char *s, *newline = "\n";
1.96 markus 383: char buf[256]; /* Must not be larger than remote_version. */
384: char remote_version[256]; /* Must be at least as big as buf. */
385:
1.103 markus 386: if ((options.protocol & SSH_PROTO_1) &&
387: (options.protocol & SSH_PROTO_2)) {
1.102 markus 388: major = PROTOCOL_MAJOR_1;
389: minor = 99;
390: } else if (options.protocol & SSH_PROTO_2) {
391: major = PROTOCOL_MAJOR_2;
392: minor = PROTOCOL_MINOR_2;
1.363 dtucker 393: newline = "\r\n";
1.102 markus 394: } else {
395: major = PROTOCOL_MAJOR_1;
396: minor = PROTOCOL_MINOR_1;
397: }
1.363 dtucker 398: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s%s", major, minor,
399: SSH_VERSION, newline);
1.96 markus 400: server_version_string = xstrdup(buf);
401:
1.272 markus 402: /* Send our protocol version identification. */
403: if (atomicio(vwrite, sock_out, server_version_string,
404: strlen(server_version_string))
405: != strlen(server_version_string)) {
406: logit("Could not write ident string to %s", get_remote_ipaddr());
1.278 markus 407: cleanup_exit(255);
1.272 markus 408: }
409:
410: /* Read other sides version identification. */
411: memset(buf, 0, sizeof(buf));
412: for (i = 0; i < sizeof(buf) - 1; i++) {
413: if (atomicio(read, sock_in, &buf[i], 1) != 1) {
414: logit("Did not receive identification string from %s",
415: get_remote_ipaddr());
1.278 markus 416: cleanup_exit(255);
1.96 markus 417: }
1.272 markus 418: if (buf[i] == '\r') {
419: buf[i] = 0;
420: /* Kludge for F-Secure Macintosh < 1.0.2 */
421: if (i == 12 &&
422: strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
1.96 markus 423: break;
1.272 markus 424: continue;
425: }
426: if (buf[i] == '\n') {
427: buf[i] = 0;
428: break;
1.96 markus 429: }
430: }
1.272 markus 431: buf[sizeof(buf) - 1] = 0;
432: client_version_string = xstrdup(buf);
1.96 markus 433:
434: /*
435: * Check that the versions match. In future this might accept
436: * several versions and set appropriate flags to handle them.
437: */
438: if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
439: &remote_major, &remote_minor, remote_version) != 3) {
1.105 markus 440: s = "Protocol mismatch.\n";
1.271 deraadt 441: (void) atomicio(vwrite, sock_out, s, strlen(s));
1.96 markus 442: close(sock_in);
443: close(sock_out);
1.264 itojun 444: logit("Bad protocol version identification '%.100s' from %s",
1.96 markus 445: client_version_string, get_remote_ipaddr());
1.278 markus 446: cleanup_exit(255);
1.96 markus 447: }
448: debug("Client protocol version %d.%d; client software version %.100s",
1.217 deraadt 449: remote_major, remote_minor, remote_version);
1.96 markus 450:
1.98 markus 451: compat_datafellows(remote_version);
1.260 mickey 452:
453: if (datafellows & SSH_BUG_PROBE) {
1.264 itojun 454: logit("probed from %s with %s. Don't panic.",
1.260 mickey 455: get_remote_ipaddr(), client_version_string);
1.278 markus 456: cleanup_exit(255);
1.260 mickey 457: }
1.175 deraadt 458:
459: if (datafellows & SSH_BUG_SCANNER) {
1.264 itojun 460: logit("scanned from %s with %s. Don't panic.",
1.175 deraadt 461: get_remote_ipaddr(), client_version_string);
1.278 markus 462: cleanup_exit(255);
1.175 deraadt 463: }
1.98 markus 464:
1.102 markus 465: mismatch = 0;
1.214 deraadt 466: switch (remote_major) {
1.96 markus 467: case 1:
1.108 markus 468: if (remote_minor == 99) {
469: if (options.protocol & SSH_PROTO_2)
470: enable_compat20();
471: else
472: mismatch = 1;
473: break;
474: }
1.102 markus 475: if (!(options.protocol & SSH_PROTO_1)) {
476: mismatch = 1;
477: break;
478: }
1.96 markus 479: if (remote_minor < 3) {
1.121 provos 480: packet_disconnect("Your ssh version is too old and "
1.96 markus 481: "is no longer supported. Please install a newer version.");
482: } else if (remote_minor == 3) {
483: /* note that this disables agent-forwarding */
484: enable_compat13();
485: }
1.102 markus 486: break;
1.98 markus 487: case 2:
1.102 markus 488: if (options.protocol & SSH_PROTO_2) {
1.98 markus 489: enable_compat20();
490: break;
491: }
1.99 markus 492: /* FALLTHROUGH */
1.105 markus 493: default:
1.102 markus 494: mismatch = 1;
495: break;
496: }
497: chop(server_version_string);
498: debug("Local version string %.200s", server_version_string);
499:
500: if (mismatch) {
1.96 markus 501: s = "Protocol major versions differ.\n";
1.271 deraadt 502: (void) atomicio(vwrite, sock_out, s, strlen(s));
1.96 markus 503: close(sock_in);
504: close(sock_out);
1.264 itojun 505: logit("Protocol major versions differ for %s: %.200s vs. %.200s",
1.102 markus 506: get_remote_ipaddr(),
507: server_version_string, client_version_string);
1.278 markus 508: cleanup_exit(255);
1.96 markus 509: }
1.108 markus 510: }
511:
1.134 markus 512: /* Destroy the host and server keys. They will no longer be needed. */
1.108 markus 513: void
514: destroy_sensitive_data(void)
515: {
1.134 markus 516: int i;
517:
518: if (sensitive_data.server_key) {
519: key_free(sensitive_data.server_key);
520: sensitive_data.server_key = NULL;
521: }
1.217 deraadt 522: for (i = 0; i < options.num_host_key_files; i++) {
1.134 markus 523: if (sensitive_data.host_keys[i]) {
524: key_free(sensitive_data.host_keys[i]);
525: sensitive_data.host_keys[i] = NULL;
526: }
527: }
528: sensitive_data.ssh1_host_key = NULL;
1.169 markus 529: memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
1.134 markus 530: }
531:
1.231 provos 532: /* Demote private to public keys for network child */
533: void
534: demote_sensitive_data(void)
535: {
536: Key *tmp;
537: int i;
538:
539: if (sensitive_data.server_key) {
540: tmp = key_demote(sensitive_data.server_key);
541: key_free(sensitive_data.server_key);
542: sensitive_data.server_key = tmp;
543: }
544:
545: for (i = 0; i < options.num_host_key_files; i++) {
546: if (sensitive_data.host_keys[i]) {
547: tmp = key_demote(sensitive_data.host_keys[i]);
548: key_free(sensitive_data.host_keys[i]);
549: sensitive_data.host_keys[i] = tmp;
550: if (tmp->type == KEY_RSA1)
551: sensitive_data.ssh1_host_key = tmp;
552: }
553: }
554:
555: /* We do not clear ssh1_host key and cookie. XXX - Okay Niels? */
556: }
557:
1.233 markus 558: static void
1.231 provos 559: privsep_preauth_child(void)
560: {
1.254 deraadt 561: u_int32_t rnd[256];
1.253 deraadt 562: gid_t gidset[1];
1.250 deraadt 563: struct passwd *pw;
1.231 provos 564:
565: /* Enable challenge-response authentication for privilege separation */
566: privsep_challenge_enable();
567:
1.354 djm 568: arc4random_stir();
1.356 djm 569: arc4random_buf(rnd, sizeof(rnd));
1.254 deraadt 570: RAND_seed(rnd, sizeof(rnd));
1.231 provos 571:
572: /* Demote the private keys to public keys. */
573: demote_sensitive_data();
574:
1.235 stevesk 575: if ((pw = getpwnam(SSH_PRIVSEP_USER)) == NULL)
1.240 djm 576: fatal("Privilege separation user %s does not exist",
577: SSH_PRIVSEP_USER);
1.235 stevesk 578: memset(pw->pw_passwd, 0, strlen(pw->pw_passwd));
579: endpwent();
580:
1.255 deraadt 581: /* Change our root directory */
1.232 stevesk 582: if (chroot(_PATH_PRIVSEP_CHROOT_DIR) == -1)
583: fatal("chroot(\"%s\"): %s", _PATH_PRIVSEP_CHROOT_DIR,
584: strerror(errno));
1.231 provos 585: if (chdir("/") == -1)
1.236 stevesk 586: fatal("chdir(\"/\"): %s", strerror(errno));
1.234 markus 587:
1.231 provos 588: /* Drop our privileges */
1.235 stevesk 589: debug3("privsep user:group %u:%u", (u_int)pw->pw_uid,
590: (u_int)pw->pw_gid);
1.251 markus 591: #if 0
1.287 djm 592: /* XXX not ready, too heavy after chroot */
1.235 stevesk 593: do_setusercontext(pw);
1.251 markus 594: #else
595: gidset[0] = pw->pw_gid;
596: if (setgroups(1, gidset) < 0)
597: fatal("setgroups: %.100s", strerror(errno));
598: permanently_set_uid(pw);
599: #endif
1.231 provos 600: }
601:
1.278 markus 602: static int
603: privsep_preauth(Authctxt *authctxt)
1.237 markus 604: {
605: int status;
606: pid_t pid;
607:
608: /* Set up unprivileged child process to deal with network data */
1.242 mouring 609: pmonitor = monitor_init();
1.237 markus 610: /* Store a pointer to the kex for later rekeying */
1.242 mouring 611: pmonitor->m_pkex = &xxx_kex;
1.237 markus 612:
613: pid = fork();
614: if (pid == -1) {
615: fatal("fork of unprivileged child failed");
616: } else if (pid != 0) {
1.245 mpech 617: debug2("Network child is on pid %ld", (long)pid);
1.237 markus 618:
1.242 mouring 619: close(pmonitor->m_recvfd);
1.285 dtucker 620: pmonitor->m_pid = pid;
1.278 markus 621: monitor_child_preauth(authctxt, pmonitor);
1.242 mouring 622: close(pmonitor->m_sendfd);
1.237 markus 623:
624: /* Sync memory */
1.242 mouring 625: monitor_sync(pmonitor);
1.237 markus 626:
627: /* Wait for the child's exit status */
1.239 markus 628: while (waitpid(pid, &status, 0) < 0)
629: if (errno != EINTR)
630: break;
1.278 markus 631: return (1);
1.237 markus 632: } else {
633: /* child */
634:
1.242 mouring 635: close(pmonitor->m_sendfd);
1.237 markus 636:
637: /* Demote the child */
638: if (getuid() == 0 || geteuid() == 0)
639: privsep_preauth_child();
1.238 stevesk 640: setproctitle("%s", "[net]");
1.237 markus 641: }
1.278 markus 642: return (0);
1.237 markus 643: }
644:
1.233 markus 645: static void
1.237 markus 646: privsep_postauth(Authctxt *authctxt)
1.231 provos 647: {
1.354 djm 648: u_int32_t rnd[256];
649:
1.231 provos 650: if (authctxt->pw->pw_uid == 0 || options.use_login) {
651: /* File descriptor passing is broken or root login */
652: use_privsep = 0;
1.315 djm 653: goto skip;
1.231 provos 654: }
1.234 markus 655:
1.231 provos 656: /* New socket pair */
1.242 mouring 657: monitor_reinit(pmonitor);
1.231 provos 658:
1.242 mouring 659: pmonitor->m_pid = fork();
660: if (pmonitor->m_pid == -1)
1.231 provos 661: fatal("fork of unprivileged child failed");
1.242 mouring 662: else if (pmonitor->m_pid != 0) {
1.364 ! markus 663: verbose("User child is on pid %ld", (long)pmonitor->m_pid);
1.242 mouring 664: close(pmonitor->m_recvfd);
1.307 otto 665: buffer_clear(&loginmsg);
1.242 mouring 666: monitor_child_postauth(pmonitor);
1.231 provos 667:
668: /* NEVERREACHED */
669: exit(0);
670: }
671:
1.242 mouring 672: close(pmonitor->m_sendfd);
1.231 provos 673:
674: /* Demote the private keys to public keys. */
675: demote_sensitive_data();
1.354 djm 676:
677: arc4random_stir();
1.356 djm 678: arc4random_buf(rnd, sizeof(rnd));
1.354 djm 679: RAND_seed(rnd, sizeof(rnd));
1.231 provos 680:
681: /* Drop privileges */
682: do_setusercontext(authctxt->pw);
683:
1.315 djm 684: skip:
1.231 provos 685: /* It is safe now to apply the key state */
1.242 mouring 686: monitor_apply_keystate(pmonitor);
1.312 markus 687:
688: /*
689: * Tell the packet layer that authentication was successful, since
690: * this information is not part of the key state.
691: */
692: packet_set_authenticated();
1.231 provos 693: }
694:
1.200 itojun 695: static char *
1.134 markus 696: list_hostkey_types(void)
697: {
1.223 markus 698: Buffer b;
1.281 jakob 699: const char *p;
700: char *ret;
1.134 markus 701: int i;
1.223 markus 702:
703: buffer_init(&b);
1.217 deraadt 704: for (i = 0; i < options.num_host_key_files; i++) {
1.134 markus 705: Key *key = sensitive_data.host_keys[i];
706: if (key == NULL)
707: continue;
1.214 deraadt 708: switch (key->type) {
1.134 markus 709: case KEY_RSA:
710: case KEY_DSA:
1.223 markus 711: if (buffer_len(&b) > 0)
712: buffer_append(&b, ",", 1);
713: p = key_ssh_name(key);
714: buffer_append(&b, p, strlen(p));
1.134 markus 715: break;
716: }
717: }
1.223 markus 718: buffer_append(&b, "\0", 1);
1.281 jakob 719: ret = xstrdup(buffer_ptr(&b));
1.223 markus 720: buffer_free(&b);
1.281 jakob 721: debug("list_hostkey_types: %s", ret);
722: return ret;
1.134 markus 723: }
724:
1.231 provos 725: Key *
1.134 markus 726: get_hostkey_by_type(int type)
727: {
728: int i;
1.250 deraadt 729:
1.217 deraadt 730: for (i = 0; i < options.num_host_key_files; i++) {
1.134 markus 731: Key *key = sensitive_data.host_keys[i];
732: if (key != NULL && key->type == type)
733: return key;
734: }
735: return NULL;
1.96 markus 736: }
737:
1.231 provos 738: Key *
739: get_hostkey_by_index(int ind)
740: {
741: if (ind < 0 || ind >= options.num_host_key_files)
742: return (NULL);
743: return (sensitive_data.host_keys[ind]);
744: }
745:
746: int
747: get_hostkey_index(Key *key)
748: {
749: int i;
1.250 deraadt 750:
1.231 provos 751: for (i = 0; i < options.num_host_key_files; i++) {
752: if (key == sensitive_data.host_keys[i])
753: return (i);
754: }
755: return (-1);
756: }
757:
1.124 markus 758: /*
759: * returns 1 if connection should be dropped, 0 otherwise.
760: * dropping starts at connection #max_startups_begin with a probability
761: * of (max_startups_rate/100). the probability increases linearly until
762: * all connections are dropped for startups > max_startups
763: */
1.200 itojun 764: static int
1.124 markus 765: drop_connection(int startups)
766: {
1.303 mickey 767: int p, r;
1.124 markus 768:
769: if (startups < options.max_startups_begin)
770: return 0;
771: if (startups >= options.max_startups)
772: return 1;
773: if (options.max_startups_rate == 100)
774: return 1;
775:
776: p = 100 - options.max_startups_rate;
777: p *= startups - options.max_startups_begin;
1.303 mickey 778: p /= options.max_startups - options.max_startups_begin;
1.124 markus 779: p += options.max_startups_rate;
1.356 djm 780: r = arc4random_uniform(100);
1.124 markus 781:
1.304 djm 782: debug("drop_connection: p %d, r %d", p, r);
1.124 markus 783: return (r < p) ? 1 : 0;
784: }
785:
1.215 markus 786: static void
787: usage(void)
788: {
1.290 markus 789: fprintf(stderr, "%s, %s\n",
1.280 markus 790: SSH_VERSION, SSLeay_version(SSLEAY_VERSION));
1.289 markus 791: fprintf(stderr,
1.359 jmc 792: "usage: sshd [-46DdeiqTt] [-b bits] [-C connection_spec] [-f config_file]\n"
793: " [-g login_grace_time] [-h host_key_file] [-k key_gen_time]\n"
794: " [-o option] [-p port] [-u len]\n"
1.289 markus 795: );
1.215 markus 796: exit(1);
797: }
798:
1.294 djm 799: static void
800: send_rexec_state(int fd, Buffer *conf)
801: {
802: Buffer m;
803:
804: debug3("%s: entering fd = %d config len %d", __func__, fd,
805: buffer_len(conf));
806:
807: /*
808: * Protocol from reexec master to child:
809: * string configuration
810: * u_int ephemeral_key_follows
811: * bignum e (only if ephemeral_key_follows == 1)
812: * bignum n "
813: * bignum d "
814: * bignum iqmp "
815: * bignum p "
816: * bignum q "
817: */
818: buffer_init(&m);
819: buffer_put_cstring(&m, buffer_ptr(conf));
820:
1.298 deraadt 821: if (sensitive_data.server_key != NULL &&
1.294 djm 822: sensitive_data.server_key->type == KEY_RSA1) {
823: buffer_put_int(&m, 1);
824: buffer_put_bignum(&m, sensitive_data.server_key->rsa->e);
825: buffer_put_bignum(&m, sensitive_data.server_key->rsa->n);
826: buffer_put_bignum(&m, sensitive_data.server_key->rsa->d);
827: buffer_put_bignum(&m, sensitive_data.server_key->rsa->iqmp);
828: buffer_put_bignum(&m, sensitive_data.server_key->rsa->p);
829: buffer_put_bignum(&m, sensitive_data.server_key->rsa->q);
830: } else
831: buffer_put_int(&m, 0);
832:
833: if (ssh_msg_send(fd, 0, &m) == -1)
834: fatal("%s: ssh_msg_send failed", __func__);
835:
836: buffer_free(&m);
837:
838: debug3("%s: done", __func__);
839: }
840:
841: static void
842: recv_rexec_state(int fd, Buffer *conf)
843: {
844: Buffer m;
845: char *cp;
846: u_int len;
847:
848: debug3("%s: entering fd = %d", __func__, fd);
849:
850: buffer_init(&m);
851:
852: if (ssh_msg_recv(fd, &m) == -1)
853: fatal("%s: ssh_msg_recv failed", __func__);
854: if (buffer_get_char(&m) != 0)
855: fatal("%s: rexec version mismatch", __func__);
856:
857: cp = buffer_get_string(&m, &len);
858: if (conf != NULL)
859: buffer_append(conf, cp, len + 1);
860: xfree(cp);
861:
862: if (buffer_get_int(&m)) {
863: if (sensitive_data.server_key != NULL)
864: key_free(sensitive_data.server_key);
865: sensitive_data.server_key = key_new_private(KEY_RSA1);
866: buffer_get_bignum(&m, sensitive_data.server_key->rsa->e);
867: buffer_get_bignum(&m, sensitive_data.server_key->rsa->n);
868: buffer_get_bignum(&m, sensitive_data.server_key->rsa->d);
869: buffer_get_bignum(&m, sensitive_data.server_key->rsa->iqmp);
870: buffer_get_bignum(&m, sensitive_data.server_key->rsa->p);
871: buffer_get_bignum(&m, sensitive_data.server_key->rsa->q);
872: rsa_generate_additional_parameters(
873: sensitive_data.server_key->rsa);
874: }
875: buffer_free(&m);
876:
877: debug3("%s: done", __func__);
878: }
879:
1.345 djm 880: /* Accept a connection from inetd */
881: static void
882: server_accept_inetd(int *sock_in, int *sock_out)
883: {
884: int fd;
885:
886: startup_pipe = -1;
887: if (rexeced_flag) {
888: close(REEXEC_CONFIG_PASS_FD);
889: *sock_in = *sock_out = dup(STDIN_FILENO);
890: if (!debug_flag) {
891: startup_pipe = dup(REEXEC_STARTUP_PIPE_FD);
892: close(REEXEC_STARTUP_PIPE_FD);
893: }
894: } else {
895: *sock_in = dup(STDIN_FILENO);
896: *sock_out = dup(STDOUT_FILENO);
897: }
898: /*
899: * We intentionally do not close the descriptors 0, 1, and 2
900: * as our code for setting the descriptors won't work if
901: * ttyfd happens to be one of those.
902: */
903: if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
904: dup2(fd, STDIN_FILENO);
905: dup2(fd, STDOUT_FILENO);
906: if (fd > STDOUT_FILENO)
907: close(fd);
908: }
909: debug("inetd sockets after dupping: %d, %d", *sock_in, *sock_out);
910: }
911:
912: /*
913: * Listen for TCP connections
914: */
915: static void
916: server_listen(void)
917: {
918: int ret, listen_sock, on = 1;
919: struct addrinfo *ai;
920: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
921:
922: for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
923: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
924: continue;
925: if (num_listen_socks >= MAX_LISTEN_SOCKS)
926: fatal("Too many listen sockets. "
927: "Enlarge MAX_LISTEN_SOCKS");
928: if ((ret = getnameinfo(ai->ai_addr, ai->ai_addrlen,
929: ntop, sizeof(ntop), strport, sizeof(strport),
930: NI_NUMERICHOST|NI_NUMERICSERV)) != 0) {
931: error("getnameinfo failed: %.100s",
1.352 dtucker 932: ssh_gai_strerror(ret));
1.345 djm 933: continue;
934: }
935: /* Create socket for listening. */
936: listen_sock = socket(ai->ai_family, ai->ai_socktype,
937: ai->ai_protocol);
938: if (listen_sock < 0) {
939: /* kernel may not support ipv6 */
940: verbose("socket: %.100s", strerror(errno));
941: continue;
942: }
943: if (set_nonblock(listen_sock) == -1) {
944: close(listen_sock);
945: continue;
946: }
947: /*
948: * Set socket options.
949: * Allow local port reuse in TIME_WAIT.
950: */
951: if (setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
952: &on, sizeof(on)) == -1)
953: error("setsockopt SO_REUSEADDR: %s", strerror(errno));
954:
955: debug("Bind to port %s on %s.", strport, ntop);
956:
957: /* Bind the socket to the desired port. */
958: if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
959: error("Bind to port %s on %s failed: %.200s.",
960: strport, ntop, strerror(errno));
961: close(listen_sock);
962: continue;
963: }
964: listen_socks[num_listen_socks] = listen_sock;
965: num_listen_socks++;
966:
967: /* Start listening on the port. */
968: if (listen(listen_sock, SSH_LISTEN_BACKLOG) < 0)
969: fatal("listen on [%s]:%s: %.100s",
970: ntop, strport, strerror(errno));
971: logit("Server listening on %s port %s.", ntop, strport);
972: }
973: freeaddrinfo(options.listen_addrs);
974:
975: if (!num_listen_socks)
976: fatal("Cannot bind any address.");
977: }
978:
979: /*
980: * The main TCP accept loop. Note that, for the non-debug case, returns
981: * from this function are in a forked subprocess.
982: */
983: static void
984: server_accept_loop(int *sock_in, int *sock_out, int *newsock, int *config_s)
985: {
986: fd_set *fdset;
987: int i, j, ret, maxfd;
988: int key_used = 0, startups = 0;
989: int startup_p[2] = { -1 , -1 };
990: struct sockaddr_storage from;
991: socklen_t fromlen;
992: pid_t pid;
993:
994: /* setup fd set for accept */
995: fdset = NULL;
996: maxfd = 0;
997: for (i = 0; i < num_listen_socks; i++)
998: if (listen_socks[i] > maxfd)
999: maxfd = listen_socks[i];
1000: /* pipes connected to unauthenticated childs */
1001: startup_pipes = xcalloc(options.max_startups, sizeof(int));
1002: for (i = 0; i < options.max_startups; i++)
1003: startup_pipes[i] = -1;
1004:
1005: /*
1006: * Stay listening for connections until the system crashes or
1007: * the daemon is killed with a signal.
1008: */
1009: for (;;) {
1010: if (received_sighup)
1011: sighup_restart();
1012: if (fdset != NULL)
1013: xfree(fdset);
1014: fdset = (fd_set *)xcalloc(howmany(maxfd + 1, NFDBITS),
1015: sizeof(fd_mask));
1016:
1017: for (i = 0; i < num_listen_socks; i++)
1018: FD_SET(listen_socks[i], fdset);
1019: for (i = 0; i < options.max_startups; i++)
1020: if (startup_pipes[i] != -1)
1021: FD_SET(startup_pipes[i], fdset);
1022:
1023: /* Wait in select until there is a connection. */
1024: ret = select(maxfd+1, fdset, NULL, NULL, NULL);
1025: if (ret < 0 && errno != EINTR)
1026: error("select: %.100s", strerror(errno));
1027: if (received_sigterm) {
1028: logit("Received signal %d; terminating.",
1029: (int) received_sigterm);
1030: close_listen_socks();
1031: unlink(options.pid_file);
1032: exit(255);
1033: }
1034: if (key_used && key_do_regen) {
1035: generate_ephemeral_server_key();
1036: key_used = 0;
1037: key_do_regen = 0;
1038: }
1039: if (ret < 0)
1040: continue;
1041:
1042: for (i = 0; i < options.max_startups; i++)
1043: if (startup_pipes[i] != -1 &&
1044: FD_ISSET(startup_pipes[i], fdset)) {
1045: /*
1046: * the read end of the pipe is ready
1047: * if the child has closed the pipe
1048: * after successful authentication
1049: * or if the child has died
1050: */
1051: close(startup_pipes[i]);
1052: startup_pipes[i] = -1;
1053: startups--;
1054: }
1055: for (i = 0; i < num_listen_socks; i++) {
1056: if (!FD_ISSET(listen_socks[i], fdset))
1057: continue;
1058: fromlen = sizeof(from);
1059: *newsock = accept(listen_socks[i],
1060: (struct sockaddr *)&from, &fromlen);
1061: if (*newsock < 0) {
1062: if (errno != EINTR && errno != EWOULDBLOCK)
1063: error("accept: %.100s", strerror(errno));
1064: continue;
1065: }
1066: if (unset_nonblock(*newsock) == -1) {
1067: close(*newsock);
1068: continue;
1069: }
1070: if (drop_connection(startups) == 1) {
1071: debug("drop connection #%d", startups);
1072: close(*newsock);
1073: continue;
1074: }
1075: if (pipe(startup_p) == -1) {
1076: close(*newsock);
1077: continue;
1078: }
1079:
1080: if (rexec_flag && socketpair(AF_UNIX,
1081: SOCK_STREAM, 0, config_s) == -1) {
1082: error("reexec socketpair: %s",
1083: strerror(errno));
1084: close(*newsock);
1085: close(startup_p[0]);
1086: close(startup_p[1]);
1087: continue;
1088: }
1089:
1090: for (j = 0; j < options.max_startups; j++)
1091: if (startup_pipes[j] == -1) {
1092: startup_pipes[j] = startup_p[0];
1093: if (maxfd < startup_p[0])
1094: maxfd = startup_p[0];
1095: startups++;
1096: break;
1097: }
1098:
1099: /*
1100: * Got connection. Fork a child to handle it, unless
1101: * we are in debugging mode.
1102: */
1103: if (debug_flag) {
1104: /*
1105: * In debugging mode. Close the listening
1106: * socket, and start processing the
1107: * connection without forking.
1108: */
1109: debug("Server will not fork when running in debugging mode.");
1110: close_listen_socks();
1111: *sock_in = *newsock;
1112: *sock_out = *newsock;
1113: close(startup_p[0]);
1114: close(startup_p[1]);
1115: startup_pipe = -1;
1116: pid = getpid();
1117: if (rexec_flag) {
1118: send_rexec_state(config_s[0],
1119: &cfg);
1120: close(config_s[0]);
1121: }
1122: break;
1123: }
1124:
1125: /*
1126: * Normal production daemon. Fork, and have
1127: * the child process the connection. The
1128: * parent continues listening.
1129: */
1130: if ((pid = fork()) == 0) {
1131: /*
1132: * Child. Close the listening and
1133: * max_startup sockets. Start using
1134: * the accepted socket. Reinitialize
1135: * logging (since our pid has changed).
1136: * We break out of the loop to handle
1137: * the connection.
1138: */
1139: startup_pipe = startup_p[1];
1140: close_startup_pipes();
1141: close_listen_socks();
1142: *sock_in = *newsock;
1143: *sock_out = *newsock;
1144: log_init(__progname,
1145: options.log_level,
1146: options.log_facility,
1147: log_stderr);
1148: if (rexec_flag)
1149: close(config_s[0]);
1150: break;
1151: }
1152:
1153: /* Parent. Stay in the loop. */
1154: if (pid < 0)
1155: error("fork: %.100s", strerror(errno));
1156: else
1157: debug("Forked child %ld.", (long)pid);
1158:
1159: close(startup_p[1]);
1160:
1161: if (rexec_flag) {
1162: send_rexec_state(config_s[0], &cfg);
1163: close(config_s[0]);
1164: close(config_s[1]);
1165: }
1166:
1167: /*
1168: * Mark that the key has been used (it
1169: * was "given" to the child).
1170: */
1171: if ((options.protocol & SSH_PROTO_1) &&
1172: key_used == 0) {
1173: /* Schedule server key regeneration alarm. */
1174: signal(SIGALRM, key_regeneration_alarm);
1175: alarm(options.key_regeneration_time);
1176: key_used = 1;
1177: }
1178:
1179: close(*newsock);
1180:
1181: /*
1182: * Ensure that our random state differs
1183: * from that of the child
1184: */
1185: arc4random_stir();
1186: }
1187:
1188: /* child process check (or debug mode) */
1189: if (num_listen_socks < 0)
1190: break;
1191: }
1192: }
1193:
1194:
1.65 deraadt 1195: /*
1196: * Main program for the daemon.
1197: */
1.2 provos 1198: int
1199: main(int ac, char **av)
1.1 deraadt 1200: {
1.64 markus 1201: extern char *optarg;
1202: extern int optind;
1.345 djm 1203: int opt, i, on = 1;
1.297 avsm 1204: int sock_in = -1, sock_out = -1, newsock = -1;
1.64 markus 1205: const char *remote_ip;
1.358 dtucker 1206: char *test_user = NULL, *test_host = NULL, *test_addr = NULL;
1.64 markus 1207: int remote_port;
1.358 dtucker 1208: char *line, *p, *cp;
1.345 djm 1209: int config_s[2] = { -1 , -1 };
1.364 ! markus 1210: u_int64_t ibytes, obytes;
1.362 dtucker 1211: mode_t new_umask;
1.278 markus 1212: Key *key;
1.230 provos 1213: Authctxt *authctxt;
1.64 markus 1214:
1.138 markus 1215: /* Save argv. */
1.64 markus 1216: saved_argv = av;
1.294 djm 1217: rexec_argc = ac;
1.313 djm 1218:
1219: /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1220: sanitise_stdfd();
1.64 markus 1221:
1222: /* Initialize configuration options to their default values. */
1223: initialize_server_options(&options);
1224:
1225: /* Parse command-line arguments. */
1.358 dtucker 1226: while ((opt = getopt(ac, av, "f:p:b:k:h:g:u:o:C:dDeiqrtQRT46")) != -1) {
1.64 markus 1227: switch (opt) {
1.75 markus 1228: case '4':
1.305 djm 1229: options.address_family = AF_INET;
1.75 markus 1230: break;
1231: case '6':
1.305 djm 1232: options.address_family = AF_INET6;
1.75 markus 1233: break;
1.64 markus 1234: case 'f':
1235: config_file_name = optarg;
1236: break;
1237: case 'd':
1.273 markus 1238: if (debug_flag == 0) {
1.127 markus 1239: debug_flag = 1;
1240: options.log_level = SYSLOG_LEVEL_DEBUG1;
1.273 markus 1241: } else if (options.log_level < SYSLOG_LEVEL_DEBUG3)
1.127 markus 1242: options.log_level++;
1.64 markus 1243: break;
1.135 markus 1244: case 'D':
1245: no_daemon_flag = 1;
1.192 lebel 1246: break;
1247: case 'e':
1248: log_stderr = 1;
1.135 markus 1249: break;
1.64 markus 1250: case 'i':
1251: inetd_flag = 1;
1252: break;
1.294 djm 1253: case 'r':
1254: rexec_flag = 0;
1255: break;
1256: case 'R':
1257: rexeced_flag = 1;
1258: inetd_flag = 1;
1259: break;
1.64 markus 1260: case 'Q':
1.158 markus 1261: /* ignored */
1.64 markus 1262: break;
1263: case 'q':
1264: options.log_level = SYSLOG_LEVEL_QUIET;
1265: break;
1266: case 'b':
1.327 deraadt 1267: options.server_key_bits = (int)strtonum(optarg, 256,
1268: 32768, NULL);
1.64 markus 1269: break;
1270: case 'p':
1.75 markus 1271: options.ports_from_cmdline = 1;
1.127 markus 1272: if (options.num_ports >= MAX_PORTS) {
1273: fprintf(stderr, "too many ports.\n");
1274: exit(1);
1275: }
1.193 stevesk 1276: options.ports[options.num_ports++] = a2port(optarg);
1277: if (options.ports[options.num_ports-1] == 0) {
1278: fprintf(stderr, "Bad port number.\n");
1279: exit(1);
1280: }
1.64 markus 1281: break;
1282: case 'g':
1.197 stevesk 1283: if ((options.login_grace_time = convtime(optarg)) == -1) {
1284: fprintf(stderr, "Invalid login grace time.\n");
1285: exit(1);
1286: }
1.64 markus 1287: break;
1288: case 'k':
1.197 stevesk 1289: if ((options.key_regeneration_time = convtime(optarg)) == -1) {
1290: fprintf(stderr, "Invalid key regeneration interval.\n");
1291: exit(1);
1292: }
1.64 markus 1293: break;
1294: case 'h':
1.134 markus 1295: if (options.num_host_key_files >= MAX_HOSTKEYS) {
1296: fprintf(stderr, "too many host keys.\n");
1297: exit(1);
1298: }
1299: options.host_key_files[options.num_host_key_files++] = optarg;
1.64 markus 1300: break;
1.203 stevesk 1301: case 't':
1302: test_flag = 1;
1303: break;
1.358 dtucker 1304: case 'T':
1305: test_flag = 2;
1306: break;
1307: case 'C':
1308: cp = optarg;
1309: while ((p = strsep(&cp, ",")) && *p != '\0') {
1310: if (strncmp(p, "addr=", 5) == 0)
1311: test_addr = xstrdup(p + 5);
1312: else if (strncmp(p, "host=", 5) == 0)
1313: test_host = xstrdup(p + 5);
1314: else if (strncmp(p, "user=", 5) == 0)
1315: test_user = xstrdup(p + 5);
1316: else {
1317: fprintf(stderr, "Invalid test "
1318: "mode specification %s\n", p);
1319: exit(1);
1320: }
1321: }
1322: break;
1.125 markus 1323: case 'u':
1.327 deraadt 1324: utmp_len = (u_int)strtonum(optarg, 0, MAXHOSTNAMELEN+1, NULL);
1.257 stevesk 1325: if (utmp_len > MAXHOSTNAMELEN) {
1326: fprintf(stderr, "Invalid utmp length.\n");
1327: exit(1);
1328: }
1.125 markus 1329: break;
1.215 markus 1330: case 'o':
1.283 markus 1331: line = xstrdup(optarg);
1332: if (process_server_config_line(&options, line,
1.337 dtucker 1333: "command-line", 0, NULL, NULL, NULL, NULL) != 0)
1.217 deraadt 1334: exit(1);
1.283 markus 1335: xfree(line);
1.215 markus 1336: break;
1.64 markus 1337: case '?':
1338: default:
1.215 markus 1339: usage();
1340: break;
1.64 markus 1341: }
1342: }
1.294 djm 1343: if (rexeced_flag || inetd_flag)
1344: rexec_flag = 0;
1.355 mbalmer 1345: if (!test_flag && (rexec_flag && (av[0] == NULL || *av[0] != '/')))
1.294 djm 1346: fatal("sshd re-exec requires execution with an absolute path");
1347: if (rexeced_flag)
1.296 djm 1348: closefrom(REEXEC_MIN_FREE_FD);
1349: else
1350: closefrom(REEXEC_DEVCRYPTO_RESERVED_FD);
1.294 djm 1351:
1.180 markus 1352: SSLeay_add_all_algorithms();
1.64 markus 1353:
1.75 markus 1354: /*
1355: * Force logging to stderr until we have loaded the private host
1356: * key (unless started from inetd)
1357: */
1.138 markus 1358: log_init(__progname,
1.224 markus 1359: options.log_level == SYSLOG_LEVEL_NOT_SET ?
1360: SYSLOG_LEVEL_INFO : options.log_level,
1361: options.log_facility == SYSLOG_FACILITY_NOT_SET ?
1362: SYSLOG_FACILITY_AUTH : options.log_facility,
1.261 markus 1363: log_stderr || !inetd_flag);
1.75 markus 1364:
1.294 djm 1365: sensitive_data.server_key = NULL;
1366: sensitive_data.ssh1_host_key = NULL;
1367: sensitive_data.have_ssh1_key = 0;
1368: sensitive_data.have_ssh2_key = 0;
1369:
1.358 dtucker 1370: /*
1371: * If we're doing an extended config test, make sure we have all of
1372: * the parameters we need. If we're not doing an extended test,
1373: * do not silently ignore connection test params.
1374: */
1.361 dtucker 1375: if (test_flag >= 2 &&
1376: (test_user != NULL || test_host != NULL || test_addr != NULL)
1.358 dtucker 1377: && (test_user == NULL || test_host == NULL || test_addr == NULL))
1378: fatal("user, host and addr are all required when testing "
1379: "Match configs");
1380: if (test_flag < 2 && (test_user != NULL || test_host != NULL ||
1381: test_addr != NULL))
1382: fatal("Config test connection parameter (-C) provided without "
1383: "test mode (-T)");
1384:
1.294 djm 1385: /* Fetch our configuration */
1386: buffer_init(&cfg);
1387: if (rexeced_flag)
1.296 djm 1388: recv_rexec_state(REEXEC_CONFIG_PASS_FD, &cfg);
1.294 djm 1389: else
1390: load_server_config(config_file_name, &cfg);
1391:
1.337 dtucker 1392: parse_server_config(&options, rexeced_flag ? "rexec" : config_file_name,
1393: &cfg, NULL, NULL, NULL);
1.64 markus 1394:
1395: /* Fill in default values for those options not explicitly set. */
1396: fill_default_server_options(&options);
1.350 dtucker 1397:
1398: /* challenge-response is implemented via keyboard interactive */
1399: if (options.challenge_response_authentication)
1400: options.kbd_interactive_authentication = 1;
1.305 djm 1401:
1402: /* set default channel AF */
1403: channel_set_af(options.address_family);
1.64 markus 1404:
1405: /* Check that there are no remaining arguments. */
1406: if (optind < ac) {
1407: fprintf(stderr, "Extra argument %s.\n", av[optind]);
1408: exit(1);
1409: }
1410:
1411: debug("sshd version %.100s", SSH_VERSION);
1412:
1.134 markus 1413: /* load private host keys */
1.329 djm 1414: sensitive_data.host_keys = xcalloc(options.num_host_key_files,
1.255 deraadt 1415: sizeof(Key *));
1.217 deraadt 1416: for (i = 0; i < options.num_host_key_files; i++)
1.141 markus 1417: sensitive_data.host_keys[i] = NULL;
1.134 markus 1418:
1.217 deraadt 1419: for (i = 0; i < options.num_host_key_files; i++) {
1.179 markus 1420: key = key_load_private(options.host_key_files[i], "", NULL);
1421: sensitive_data.host_keys[i] = key;
1.134 markus 1422: if (key == NULL) {
1.195 markus 1423: error("Could not load host key: %s",
1424: options.host_key_files[i]);
1.179 markus 1425: sensitive_data.host_keys[i] = NULL;
1.134 markus 1426: continue;
1427: }
1.214 deraadt 1428: switch (key->type) {
1.134 markus 1429: case KEY_RSA1:
1430: sensitive_data.ssh1_host_key = key;
1431: sensitive_data.have_ssh1_key = 1;
1432: break;
1433: case KEY_RSA:
1434: case KEY_DSA:
1435: sensitive_data.have_ssh2_key = 1;
1436: break;
1437: }
1.179 markus 1438: debug("private host key: #%d type %d %s", i, key->type,
1439: key_type(key));
1.134 markus 1440: }
1441: if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
1.264 itojun 1442: logit("Disabling protocol version 1. Could not load host key");
1.108 markus 1443: options.protocol &= ~SSH_PROTO_1;
1444: }
1.134 markus 1445: if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
1.264 itojun 1446: logit("Disabling protocol version 2. Could not load host key");
1.134 markus 1447: options.protocol &= ~SSH_PROTO_2;
1.108 markus 1448: }
1.162 stevesk 1449: if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1.264 itojun 1450: logit("sshd: no hostkeys available -- exiting.");
1.64 markus 1451: exit(1);
1452: }
1453:
1.108 markus 1454: /* Check certain values for sanity. */
1455: if (options.protocol & SSH_PROTO_1) {
1456: if (options.server_key_bits < 512 ||
1457: options.server_key_bits > 32768) {
1458: fprintf(stderr, "Bad server key size.\n");
1459: exit(1);
1460: }
1461: /*
1462: * Check that server and host key lengths differ sufficiently. This
1463: * is necessary to make double encryption work with rsaref. Oh, I
1464: * hate software patents. I dont know if this can go? Niels
1465: */
1466: if (options.server_key_bits >
1.250 deraadt 1467: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) -
1468: SSH_KEY_BITS_RESERVED && options.server_key_bits <
1469: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1470: SSH_KEY_BITS_RESERVED) {
1.108 markus 1471: options.server_key_bits =
1.250 deraadt 1472: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1473: SSH_KEY_BITS_RESERVED;
1.108 markus 1474: debug("Forcing server key to %d bits to make it differ from host key.",
1475: options.server_key_bits);
1476: }
1.244 markus 1477: }
1478:
1479: if (use_privsep) {
1480: struct stat st;
1481:
1.327 deraadt 1482: if (getpwnam(SSH_PRIVSEP_USER) == NULL)
1.244 markus 1483: fatal("Privilege separation user %s does not exist",
1484: SSH_PRIVSEP_USER);
1485: if ((stat(_PATH_PRIVSEP_CHROOT_DIR, &st) == -1) ||
1486: (S_ISDIR(st.st_mode) == 0))
1487: fatal("Missing privilege separation directory: %s",
1.247 stevesk 1488: _PATH_PRIVSEP_CHROOT_DIR);
1489: if (st.st_uid != 0 || (st.st_mode & (S_IWGRP|S_IWOTH)) != 0)
1.262 markus 1490: fatal("%s must be owned by root and not group or "
1491: "world-writable.", _PATH_PRIVSEP_CHROOT_DIR);
1.358 dtucker 1492: }
1493:
1494: if (test_flag > 1) {
1495: if (test_user != NULL && test_addr != NULL && test_host != NULL)
1496: parse_server_match_config(&options, test_user,
1497: test_host, test_addr);
1498: dump_config(&options);
1.108 markus 1499: }
1.203 stevesk 1500:
1501: /* Configuration looks good, so exit if in test mode. */
1502: if (test_flag)
1503: exit(0);
1.108 markus 1504:
1.294 djm 1505: if (rexec_flag) {
1.329 djm 1506: rexec_argv = xcalloc(rexec_argc + 2, sizeof(char *));
1.294 djm 1507: for (i = 0; i < rexec_argc; i++) {
1508: debug("rexec_argv[%d]='%s'", i, saved_argv[i]);
1509: rexec_argv[i] = saved_argv[i];
1510: }
1511: rexec_argv[rexec_argc] = "-R";
1512: rexec_argv[rexec_argc + 1] = NULL;
1513: }
1.362 dtucker 1514:
1515: /* Ensure that umask disallows at least group and world write */
1516: new_umask = umask(0077) | 0022;
1517: (void) umask(new_umask);
1.294 djm 1518:
1.108 markus 1519: /* Initialize the log (it is reinitialized below in case we forked). */
1.306 dtucker 1520: if (debug_flag && (!inetd_flag || rexeced_flag))
1.64 markus 1521: log_stderr = 1;
1.138 markus 1522: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.64 markus 1523:
1.108 markus 1524: /*
1525: * If not in debugging mode, and not started from inetd, disconnect
1526: * from the controlling terminal, and fork. The original process
1527: * exits.
1528: */
1.135 markus 1529: if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1.64 markus 1530: int fd;
1.345 djm 1531:
1.64 markus 1532: if (daemon(0, 0) < 0)
1533: fatal("daemon() failed: %.200s", strerror(errno));
1534:
1535: /* Disconnect from the controlling tty. */
1.165 itojun 1536: fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1.64 markus 1537: if (fd >= 0) {
1538: (void) ioctl(fd, TIOCNOTTY, NULL);
1539: close(fd);
1540: }
1541: }
1542: /* Reinitialize the log (because of the fork above). */
1.138 markus 1543: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.64 markus 1544:
1545: /* Initialize the random number generator. */
1546: arc4random_stir();
1547:
1548: /* Chdir to the root directory so that the current disk can be
1549: unmounted if desired. */
1550: chdir("/");
1.217 deraadt 1551:
1.178 markus 1552: /* ignore SIGPIPE */
1553: signal(SIGPIPE, SIG_IGN);
1.64 markus 1554:
1.345 djm 1555: /* Get a connection, either from inetd or a listening TCP socket */
1.64 markus 1556: if (inetd_flag) {
1.345 djm 1557: server_accept_inetd(&sock_in, &sock_out);
1.64 markus 1558: } else {
1.345 djm 1559: server_listen();
1.75 markus 1560:
1.201 markus 1561: if (options.protocol & SSH_PROTO_1)
1562: generate_ephemeral_server_key();
1563:
1564: signal(SIGHUP, sighup_handler);
1.345 djm 1565: signal(SIGCHLD, main_sigchld_handler);
1.201 markus 1566: signal(SIGTERM, sigterm_handler);
1567: signal(SIGQUIT, sigterm_handler);
1568:
1.345 djm 1569: /*
1570: * Write out the pid file after the sigterm handler
1571: * is setup and the listen sockets are bound
1572: */
1573: if (!debug_flag) {
1574: FILE *f = fopen(options.pid_file, "w");
1.201 markus 1575:
1.270 djm 1576: if (f == NULL) {
1577: error("Couldn't create pid file \"%s\": %s",
1578: options.pid_file, strerror(errno));
1579: } else {
1.245 mpech 1580: fprintf(f, "%ld\n", (long) getpid());
1.64 markus 1581: fclose(f);
1582: }
1583: }
1584:
1.345 djm 1585: /* Accept a connection and return in a forked child */
1586: server_accept_loop(&sock_in, &sock_out,
1587: &newsock, config_s);
1.1 deraadt 1588: }
1589:
1.64 markus 1590: /* This is the child processing a new connection. */
1.288 markus 1591: setproctitle("%s", "[accepted]");
1.294 djm 1592:
1.300 markus 1593: /*
1594: * Create a new session and process group since the 4.4BSD
1595: * setlogin() affects the entire process group. We don't
1596: * want the child to be able to affect the parent.
1597: */
1598: if (!debug_flag && !inetd_flag && setsid() < 0)
1599: error("setsid: %.100s", strerror(errno));
1600:
1.294 djm 1601: if (rexec_flag) {
1602: int fd;
1603:
1.296 djm 1604: debug("rexec start in %d out %d newsock %d pipe %d sock %d",
1605: sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1.294 djm 1606: dup2(newsock, STDIN_FILENO);
1607: dup2(STDIN_FILENO, STDOUT_FILENO);
1608: if (startup_pipe == -1)
1.296 djm 1609: close(REEXEC_STARTUP_PIPE_FD);
1.294 djm 1610: else
1.296 djm 1611: dup2(startup_pipe, REEXEC_STARTUP_PIPE_FD);
1.294 djm 1612:
1.296 djm 1613: dup2(config_s[1], REEXEC_CONFIG_PASS_FD);
1.294 djm 1614: close(config_s[1]);
1.301 dtucker 1615: if (startup_pipe != -1)
1616: close(startup_pipe);
1.296 djm 1617:
1.294 djm 1618: execv(rexec_argv[0], rexec_argv);
1619:
1620: /* Reexec has failed, fall back and continue */
1621: error("rexec of %s failed: %s", rexec_argv[0], strerror(errno));
1.296 djm 1622: recv_rexec_state(REEXEC_CONFIG_PASS_FD, NULL);
1.294 djm 1623: log_init(__progname, options.log_level,
1624: options.log_facility, log_stderr);
1625:
1626: /* Clean up fds */
1.296 djm 1627: startup_pipe = REEXEC_STARTUP_PIPE_FD;
1.294 djm 1628: close(config_s[1]);
1.296 djm 1629: close(REEXEC_CONFIG_PASS_FD);
1630: newsock = sock_out = sock_in = dup(STDIN_FILENO);
1.294 djm 1631: if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1632: dup2(fd, STDIN_FILENO);
1633: dup2(fd, STDOUT_FILENO);
1634: if (fd > STDERR_FILENO)
1635: close(fd);
1636: }
1.296 djm 1637: debug("rexec cleanup in %d out %d newsock %d pipe %d sock %d",
1638: sock_in, sock_out, newsock, startup_pipe, config_s[0]);
1.294 djm 1639: }
1.64 markus 1640:
1.66 markus 1641: /*
1642: * Disable the key regeneration alarm. We will not regenerate the
1643: * key since we are no longer in a position to give it to anyone. We
1644: * will not restart on SIGHUP since it no longer makes sense.
1645: */
1.64 markus 1646: alarm(0);
1647: signal(SIGALRM, SIG_DFL);
1648: signal(SIGHUP, SIG_DFL);
1649: signal(SIGTERM, SIG_DFL);
1650: signal(SIGQUIT, SIG_DFL);
1651: signal(SIGCHLD, SIG_DFL);
1.150 markus 1652:
1.66 markus 1653: /*
1654: * Register our connection. This turns encryption off because we do
1655: * not have a key.
1656: */
1.64 markus 1657: packet_set_connection(sock_in, sock_out);
1.312 markus 1658: packet_set_server();
1.309 djm 1659:
1660: /* Set SO_KEEPALIVE if requested. */
1661: if (options.tcp_keep_alive && packet_connection_is_on_socket() &&
1662: setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof(on)) < 0)
1663: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.1 deraadt 1664:
1.310 markus 1665: if ((remote_port = get_remote_port()) < 0) {
1666: debug("get_remote_port failed");
1667: cleanup_exit(255);
1668: }
1.316 dtucker 1669:
1670: /*
1671: * We use get_canonical_hostname with usedns = 0 instead of
1672: * get_remote_ipaddr here so IP options will be checked.
1673: */
1.331 markus 1674: (void) get_canonical_hostname(0);
1675: /*
1676: * The rest of the code depends on the fact that
1677: * get_remote_ipaddr() caches the remote ip, even if
1678: * the socket goes away.
1679: */
1680: remote_ip = get_remote_ipaddr();
1.52 markus 1681:
1.209 markus 1682: #ifdef LIBWRAP
1.64 markus 1683: /* Check whether logins are denied from this host. */
1.295 djm 1684: if (packet_connection_is_on_socket()) {
1.64 markus 1685: struct request_info req;
1.37 dugsong 1686:
1.204 camield 1687: request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1.64 markus 1688: fromhost(&req);
1.37 dugsong 1689:
1.64 markus 1690: if (!hosts_access(&req)) {
1.209 markus 1691: debug("Connection refused by tcp wrapper");
1.182 markus 1692: refuse(&req);
1.209 markus 1693: /* NOTREACHED */
1694: fatal("libwrap refuse returns");
1.64 markus 1695: }
1696: }
1.75 markus 1697: #endif /* LIBWRAP */
1.209 markus 1698:
1.64 markus 1699: /* Log the connection. */
1700: verbose("Connection from %.500s port %d", remote_ip, remote_port);
1.1 deraadt 1701:
1.66 markus 1702: /*
1.317 djm 1703: * We don't want to listen forever unless the other side
1.66 markus 1704: * successfully authenticates itself. So we set up an alarm which is
1705: * cleared after successful authentication. A limit of zero
1.317 djm 1706: * indicates no limit. Note that we don't set the alarm in debugging
1.66 markus 1707: * mode; it is just annoying to have the server exit just when you
1708: * are about to discover the bug.
1709: */
1.64 markus 1710: signal(SIGALRM, grace_alarm_handler);
1711: if (!debug_flag)
1712: alarm(options.login_grace_time);
1713:
1.96 markus 1714: sshd_exchange_identification(sock_in, sock_out);
1.353 dtucker 1715:
1716: /* In inetd mode, generate ephemeral key only for proto 1 connections */
1717: if (!compat20 && inetd_flag && sensitive_data.server_key == NULL)
1718: generate_ephemeral_server_key();
1.275 markus 1719:
1.64 markus 1720: packet_set_nonblocking();
1.1 deraadt 1721:
1.278 markus 1722: /* allocate authentication context */
1.329 djm 1723: authctxt = xcalloc(1, sizeof(*authctxt));
1.278 markus 1724:
1725: /* XXX global for cleanup, access from other modules */
1726: the_authctxt = authctxt;
1727:
1.307 otto 1728: /* prepare buffer to collect messages to display to user after login */
1729: buffer_init(&loginmsg);
1730:
1.237 markus 1731: if (use_privsep)
1.278 markus 1732: if (privsep_preauth(authctxt) == 1)
1.237 markus 1733: goto authenticated;
1.231 provos 1734:
1.77 markus 1735: /* perform the key exchange */
1736: /* authenticate user and start session */
1.98 markus 1737: if (compat20) {
1738: do_ssh2_kex();
1.278 markus 1739: do_authentication2(authctxt);
1.98 markus 1740: } else {
1741: do_ssh1_kex();
1.278 markus 1742: do_authentication(authctxt);
1.98 markus 1743: }
1.237 markus 1744: /*
1745: * If we use privilege separation, the unprivileged child transfers
1746: * the current keystate and exits
1747: */
1748: if (use_privsep) {
1.242 mouring 1749: mm_send_keystate(pmonitor);
1.231 provos 1750: exit(0);
1.237 markus 1751: }
1.231 provos 1752:
1753: authenticated:
1.318 djm 1754: /*
1755: * Cancel the alarm we set to limit the time taken for
1756: * authentication.
1757: */
1758: alarm(0);
1759: signal(SIGALRM, SIG_DFL);
1.347 markus 1760: authctxt->authenticated = 1;
1.318 djm 1761: if (startup_pipe != -1) {
1762: close(startup_pipe);
1763: startup_pipe = -1;
1764: }
1765:
1.234 markus 1766: /*
1.231 provos 1767: * In privilege separation, we fork another child and prepare
1768: * file descriptor passing.
1769: */
1770: if (use_privsep) {
1.237 markus 1771: privsep_postauth(authctxt);
1772: /* the monitor process [priv] will not return */
1.231 provos 1773: if (!compat20)
1774: destroy_sensitive_data();
1775: }
1.360 dtucker 1776:
1777: packet_set_timeout(options.client_alive_interval,
1778: options.client_alive_count_max);
1.230 provos 1779:
1.278 markus 1780: /* Start session. */
1.230 provos 1781: do_authenticated(authctxt);
1782:
1.64 markus 1783: /* The connection has been terminated. */
1.364 ! markus 1784: packet_get_state(MODE_IN, NULL, NULL, NULL, &ibytes);
! 1785: packet_get_state(MODE_OUT, NULL, NULL, NULL, &obytes);
! 1786: verbose("Transferred: sent %llu, received %llu bytes", obytes, ibytes);
! 1787:
! 1788: verbose("Closing connection to %.500s port %d", remote_ip, remote_port);
1.64 markus 1789: packet_close();
1.231 provos 1790:
1791: if (use_privsep)
1792: mm_terminate();
1793:
1.64 markus 1794: exit(0);
1.1 deraadt 1795: }
1796:
1.65 deraadt 1797: /*
1.229 markus 1798: * Decrypt session_key_int using our private server key and private host key
1799: * (key with larger modulus first).
1800: */
1.231 provos 1801: int
1.229 markus 1802: ssh1_session_key(BIGNUM *session_key_int)
1803: {
1804: int rsafail = 0;
1805:
1.327 deraadt 1806: if (BN_cmp(sensitive_data.server_key->rsa->n,
1807: sensitive_data.ssh1_host_key->rsa->n) > 0) {
1.229 markus 1808: /* Server key has bigger modulus. */
1809: if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1.327 deraadt 1810: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) +
1811: SSH_KEY_BITS_RESERVED) {
1812: fatal("do_connection: %s: "
1813: "server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1.229 markus 1814: get_remote_ipaddr(),
1815: BN_num_bits(sensitive_data.server_key->rsa->n),
1816: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1817: SSH_KEY_BITS_RESERVED);
1818: }
1819: if (rsa_private_decrypt(session_key_int, session_key_int,
1820: sensitive_data.server_key->rsa) <= 0)
1821: rsafail++;
1822: if (rsa_private_decrypt(session_key_int, session_key_int,
1823: sensitive_data.ssh1_host_key->rsa) <= 0)
1824: rsafail++;
1825: } else {
1826: /* Host key has bigger modulus (or they are equal). */
1827: if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1.327 deraadt 1828: BN_num_bits(sensitive_data.server_key->rsa->n) +
1829: SSH_KEY_BITS_RESERVED) {
1830: fatal("do_connection: %s: "
1831: "host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1.229 markus 1832: get_remote_ipaddr(),
1833: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1834: BN_num_bits(sensitive_data.server_key->rsa->n),
1835: SSH_KEY_BITS_RESERVED);
1836: }
1837: if (rsa_private_decrypt(session_key_int, session_key_int,
1838: sensitive_data.ssh1_host_key->rsa) < 0)
1839: rsafail++;
1840: if (rsa_private_decrypt(session_key_int, session_key_int,
1841: sensitive_data.server_key->rsa) < 0)
1842: rsafail++;
1843: }
1844: return (rsafail);
1845: }
1846: /*
1.77 markus 1847: * SSH1 key exchange
1.65 deraadt 1848: */
1.200 itojun 1849: static void
1.142 markus 1850: do_ssh1_kex(void)
1.1 deraadt 1851: {
1.64 markus 1852: int i, len;
1.159 markus 1853: int rsafail = 0;
1.64 markus 1854: BIGNUM *session_key_int;
1.140 markus 1855: u_char session_key[SSH_SESSION_KEY_LENGTH];
1856: u_char cookie[8];
1857: u_int cipher_type, auth_mask, protocol_flags;
1.64 markus 1858:
1.66 markus 1859: /*
1860: * Generate check bytes that the client must send back in the user
1861: * packet in order for it to be accepted; this is used to defy ip
1862: * spoofing attacks. Note that this only works against somebody
1863: * doing IP spoofing from a remote machine; any machine on the local
1864: * network can still see outgoing packets and catch the random
1865: * cookie. This only affects rhosts authentication, and this is one
1866: * of the reasons why it is inherently insecure.
1867: */
1.356 djm 1868: arc4random_buf(cookie, sizeof(cookie));
1.64 markus 1869:
1.66 markus 1870: /*
1871: * Send our public key. We include in the packet 64 bits of random
1872: * data that must be matched in the reply in order to prevent IP
1873: * spoofing.
1874: */
1.64 markus 1875: packet_start(SSH_SMSG_PUBLIC_KEY);
1876: for (i = 0; i < 8; i++)
1.77 markus 1877: packet_put_char(cookie[i]);
1.64 markus 1878:
1879: /* Store our public server RSA key. */
1.134 markus 1880: packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1881: packet_put_bignum(sensitive_data.server_key->rsa->e);
1882: packet_put_bignum(sensitive_data.server_key->rsa->n);
1.64 markus 1883:
1884: /* Store our public host RSA key. */
1.134 markus 1885: packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1886: packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1887: packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1.64 markus 1888:
1889: /* Put protocol flags. */
1890: packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1891:
1892: /* Declare which ciphers we support. */
1.131 markus 1893: packet_put_int(cipher_mask_ssh1(0));
1.64 markus 1894:
1895: /* Declare supported authentication types. */
1896: auth_mask = 0;
1897: if (options.rhosts_rsa_authentication)
1898: auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1899: if (options.rsa_authentication)
1900: auth_mask |= 1 << SSH_AUTH_RSA;
1.196 markus 1901: if (options.challenge_response_authentication == 1)
1.64 markus 1902: auth_mask |= 1 << SSH_AUTH_TIS;
1903: if (options.password_authentication)
1904: auth_mask |= 1 << SSH_AUTH_PASSWORD;
1905: packet_put_int(auth_mask);
1906:
1907: /* Send the packet and wait for it to be sent. */
1908: packet_send();
1909: packet_write_wait();
1910:
1.134 markus 1911: debug("Sent %d bit server key and %d bit host key.",
1912: BN_num_bits(sensitive_data.server_key->rsa->n),
1913: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1.64 markus 1914:
1915: /* Read clients reply (cipher type and session key). */
1.222 markus 1916: packet_read_expect(SSH_CMSG_SESSION_KEY);
1.64 markus 1917:
1.69 markus 1918: /* Get cipher type and check whether we accept this. */
1.64 markus 1919: cipher_type = packet_get_char();
1.69 markus 1920:
1.131 markus 1921: if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1.69 markus 1922: packet_disconnect("Warning: client selects unsupported cipher.");
1.64 markus 1923:
1924: /* Get check bytes from the packet. These must match those we
1925: sent earlier with the public key packet. */
1926: for (i = 0; i < 8; i++)
1.77 markus 1927: if (cookie[i] != packet_get_char())
1.64 markus 1928: packet_disconnect("IP Spoofing check bytes do not match.");
1929:
1930: debug("Encryption type: %.200s", cipher_name(cipher_type));
1931:
1932: /* Get the encrypted integer. */
1.218 markus 1933: if ((session_key_int = BN_new()) == NULL)
1934: fatal("do_ssh1_kex: BN_new failed");
1.221 markus 1935: packet_get_bignum(session_key_int);
1.64 markus 1936:
1937: protocol_flags = packet_get_int();
1938: packet_set_protocol_flags(protocol_flags);
1.220 markus 1939: packet_check_eom();
1.64 markus 1940:
1.229 markus 1941: /* Decrypt session_key_int using host/server keys */
1.231 provos 1942: rsafail = PRIVSEP(ssh1_session_key(session_key_int));
1943:
1.66 markus 1944: /*
1945: * Extract session key from the decrypted integer. The key is in the
1946: * least significant 256 bits of the integer; the first byte of the
1947: * key is in the highest bits.
1948: */
1.159 markus 1949: if (!rsafail) {
1.348 markus 1950: (void) BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1.159 markus 1951: len = BN_num_bytes(session_key_int);
1.311 djm 1952: if (len < 0 || (u_int)len > sizeof(session_key)) {
1.348 markus 1953: error("do_ssh1_kex: bad session key len from %s: "
1.165 itojun 1954: "session_key_int %d > sizeof(session_key) %lu",
1955: get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1.159 markus 1956: rsafail++;
1957: } else {
1958: memset(session_key, 0, sizeof(session_key));
1959: BN_bn2bin(session_key_int,
1960: session_key + sizeof(session_key) - len);
1.169 markus 1961:
1.291 djm 1962: derive_ssh1_session_id(
1.298 deraadt 1963: sensitive_data.ssh1_host_key->rsa->n,
1.291 djm 1964: sensitive_data.server_key->rsa->n,
1965: cookie, session_id);
1.169 markus 1966: /*
1967: * Xor the first 16 bytes of the session key with the
1968: * session id.
1969: */
1970: for (i = 0; i < 16; i++)
1971: session_key[i] ^= session_id[i];
1.159 markus 1972: }
1973: }
1974: if (rsafail) {
1.169 markus 1975: int bytes = BN_num_bytes(session_key_int);
1.227 stevesk 1976: u_char *buf = xmalloc(bytes);
1.169 markus 1977: MD5_CTX md;
1978:
1.264 itojun 1979: logit("do_connection: generating a fake encryption key");
1.169 markus 1980: BN_bn2bin(session_key_int, buf);
1981: MD5_Init(&md);
1982: MD5_Update(&md, buf, bytes);
1983: MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1984: MD5_Final(session_key, &md);
1985: MD5_Init(&md);
1986: MD5_Update(&md, session_key, 16);
1987: MD5_Update(&md, buf, bytes);
1988: MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1989: MD5_Final(session_key + 16, &md);
1990: memset(buf, 0, bytes);
1991: xfree(buf);
1.170 markus 1992: for (i = 0; i < 16; i++)
1993: session_id[i] = session_key[i] ^ session_key[i + 16];
1.159 markus 1994: }
1.231 provos 1995: /* Destroy the private and public keys. No longer. */
1.169 markus 1996: destroy_sensitive_data();
1997:
1.231 provos 1998: if (use_privsep)
1999: mm_ssh1_session_id(session_id);
2000:
1.77 markus 2001: /* Destroy the decrypted integer. It is no longer needed. */
2002: BN_clear_free(session_key_int);
1.64 markus 2003:
2004: /* Set the session key. From this on all communications will be encrypted. */
2005: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
2006:
2007: /* Destroy our copy of the session key. It is no longer needed. */
2008: memset(session_key, 0, sizeof(session_key));
2009:
2010: debug("Received session key; encryption turned on.");
2011:
1.243 deraadt 2012: /* Send an acknowledgment packet. Note that this packet is sent encrypted. */
1.64 markus 2013: packet_start(SSH_SMSG_SUCCESS);
2014: packet_send();
2015: packet_write_wait();
1.98 markus 2016: }
2017:
2018: /*
2019: * SSH2 key exchange: diffie-hellman-group1-sha1
2020: */
1.200 itojun 2021: static void
1.142 markus 2022: do_ssh2_kex(void)
1.98 markus 2023: {
2024: Kex *kex;
1.102 markus 2025:
2026: if (options.ciphers != NULL) {
1.105 markus 2027: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1.102 markus 2028: myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1.166 markus 2029: }
1.184 stevesk 2030: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
2031: compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
2032: myproposal[PROPOSAL_ENC_ALGS_STOC] =
2033: compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
2034:
1.166 markus 2035: if (options.macs != NULL) {
2036: myproposal[PROPOSAL_MAC_ALGS_CTOS] =
2037: myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1.246 markus 2038: }
1.312 markus 2039: if (options.compression == COMP_NONE) {
1.246 markus 2040: myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2041: myproposal[PROPOSAL_COMP_ALGS_STOC] = "none";
1.312 markus 2042: } else if (options.compression == COMP_DELAYED) {
2043: myproposal[PROPOSAL_COMP_ALGS_CTOS] =
2044: myproposal[PROPOSAL_COMP_ALGS_STOC] = "none,zlib@openssh.com";
1.102 markus 2045: }
1.327 deraadt 2046:
1.134 markus 2047: myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
2048:
1.189 markus 2049: /* start key exchange */
1.188 markus 2050: kex = kex_setup(myproposal);
1.263 markus 2051: kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server;
1.292 djm 2052: kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server;
1.263 markus 2053: kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1.324 djm 2054: kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
1.186 markus 2055: kex->server = 1;
2056: kex->client_version_string=client_version_string;
2057: kex->server_version_string=server_version_string;
2058: kex->load_host_key=&get_hostkey_by_type;
1.231 provos 2059: kex->host_key_index=&get_hostkey_index;
1.129 provos 2060:
1.189 markus 2061: xxx_kex = kex;
2062:
1.190 markus 2063: dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
1.187 markus 2064:
2065: session_id2 = kex->session_id;
2066: session_id2_len = kex->session_id_len;
1.129 provos 2067:
2068: #ifdef DEBUG_KEXDH
2069: /* send 1st encrypted/maced/compressed message */
2070: packet_start(SSH2_MSG_IGNORE);
2071: packet_put_cstring("markus");
2072: packet_send();
2073: packet_write_wait();
2074: #endif
1.186 markus 2075: debug("KEX done");
1.278 markus 2076: }
2077:
2078: /* server specific fatal cleanup */
2079: void
2080: cleanup_exit(int i)
2081: {
2082: if (the_authctxt)
2083: do_cleanup(the_authctxt);
2084: _exit(i);
1.1 deraadt 2085: }
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