Annotation of src/usr.bin/ssh/sshd.c, Revision 1.195.2.2
1.86 markus 1: /*
1.65 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
1.126 deraadt 5: * This program is the ssh daemon. It listens for connections from clients,
6: * and performs authentication, executes use commands or shell, and forwards
1.65 deraadt 7: * information to/from the application to the user client over an encrypted
1.126 deraadt 8: * connection. This can also handle forwarding of X11, TCP/IP, and
9: * authentication agent connections.
1.98 markus 10: *
1.126 deraadt 11: * As far as I am concerned, the code I have written for this software
12: * can be used freely for any purpose. Any derived versions of this
13: * software must be clearly marked as such, and if the derived work is
14: * incompatible with the protocol description in the RFC file, it must be
15: * called by a name other than "ssh" or "Secure Shell".
16: *
17: * SSH2 implementation:
18: *
19: * Copyright (c) 2000 Markus Friedl. All rights reserved.
20: *
21: * Redistribution and use in source and binary forms, with or without
22: * modification, are permitted provided that the following conditions
23: * are met:
24: * 1. Redistributions of source code must retain the above copyright
25: * notice, this list of conditions and the following disclaimer.
26: * 2. Redistributions in binary form must reproduce the above copyright
27: * notice, this list of conditions and the following disclaimer in the
28: * documentation and/or other materials provided with the distribution.
29: *
30: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
31: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
32: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
33: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
34: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
35: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
36: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
37: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
38: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
39: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.65 deraadt 40: */
1.1 deraadt 41:
42: #include "includes.h"
1.195.2.2! miod 43: RCSID("$OpenBSD: sshd.c,v 1.195.2.1 2001/09/27 19:03:55 jason Exp $");
1.1 deraadt 44:
1.155 markus 45: #include <openssl/dh.h>
46: #include <openssl/bn.h>
47: #include <openssl/hmac.h>
48:
49: #include "ssh.h"
50: #include "ssh1.h"
51: #include "ssh2.h"
1.1 deraadt 52: #include "xmalloc.h"
53: #include "rsa.h"
1.171 djm 54: #include "sshpty.h"
1.1 deraadt 55: #include "packet.h"
56: #include "mpaux.h"
1.155 markus 57: #include "log.h"
1.1 deraadt 58: #include "servconf.h"
59: #include "uidswap.h"
1.33 markus 60: #include "compat.h"
1.96 markus 61: #include "buffer.h"
1.155 markus 62: #include "cipher.h"
1.98 markus 63: #include "kex.h"
1.96 markus 64: #include "key.h"
1.129 provos 65: #include "dh.h"
1.98 markus 66: #include "myproposal.h"
1.108 markus 67: #include "authfile.h"
1.154 markus 68: #include "pathnames.h"
1.155 markus 69: #include "atomicio.h"
70: #include "canohost.h"
71: #include "auth.h"
72: #include "misc.h"
1.186 markus 73: #include "dispatch.h"
1.195.2.2! miod 74: #include "channels.h"
1.1 deraadt 75:
76: #ifdef LIBWRAP
77: #include <tcpd.h>
78: #include <syslog.h>
79: int allow_severity = LOG_INFO;
80: int deny_severity = LOG_WARNING;
81: #endif /* LIBWRAP */
82:
83: #ifndef O_NOCTTY
84: #define O_NOCTTY 0
85: #endif
86:
1.138 markus 87: extern char *__progname;
88:
1.1 deraadt 89: /* Server configuration options. */
90: ServerOptions options;
91:
92: /* Name of the server configuration file. */
1.154 markus 93: char *config_file_name = _PATH_SERVER_CONFIG_FILE;
1.1 deraadt 94:
1.105 markus 95: /*
1.75 markus 96: * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
97: * Default value is AF_UNSPEC means both IPv4 and IPv6.
98: */
99: int IPv4or6 = AF_UNSPEC;
100:
1.65 deraadt 101: /*
102: * Debug mode flag. This can be set on the command line. If debug
103: * mode is enabled, extra debugging output will be sent to the system
104: * log, the daemon will not go to background, and will exit after processing
105: * the first connection.
106: */
1.1 deraadt 107: int debug_flag = 0;
108:
1.195.2.1 jason 109: /* Flag indicating that the daemon should only test the configuration and keys. */
110: int test_flag = 0;
111:
1.1 deraadt 112: /* Flag indicating that the daemon is being started from inetd. */
113: int inetd_flag = 0;
114:
1.135 markus 115: /* Flag indicating that sshd should not detach and become a daemon. */
116: int no_daemon_flag = 0;
117:
1.47 markus 118: /* debug goes to stderr unless inetd_flag is set */
119: int log_stderr = 0;
120:
1.1 deraadt 121: /* Saved arguments to main(). */
122: char **saved_argv;
123:
1.66 markus 124: /*
1.75 markus 125: * The sockets that the server is listening; this is used in the SIGHUP
126: * signal handler.
1.66 markus 127: */
1.75 markus 128: #define MAX_LISTEN_SOCKS 16
129: int listen_socks[MAX_LISTEN_SOCKS];
130: int num_listen_socks = 0;
1.1 deraadt 131:
1.66 markus 132: /*
133: * the client's version string, passed by sshd2 in compat mode. if != NULL,
134: * sshd will skip the version-number exchange
135: */
1.61 markus 136: char *client_version_string = NULL;
1.96 markus 137: char *server_version_string = NULL;
1.1 deraadt 138:
1.189 markus 139: /* for rekeying XXX fixme */
140: Kex *xxx_kex;
141:
1.66 markus 142: /*
143: * Any really sensitive data in the application is contained in this
144: * structure. The idea is that this structure could be locked into memory so
145: * that the pages do not get written into swap. However, there are some
146: * problems. The private key contains BIGNUMs, and we do not (in principle)
147: * have access to the internals of them, and locking just the structure is
148: * not very useful. Currently, memory locking is not implemented.
149: */
1.64 markus 150: struct {
1.174 deraadt 151: Key *server_key; /* ephemeral server key */
1.134 markus 152: Key *ssh1_host_key; /* ssh1 host key */
153: Key **host_keys; /* all private host keys */
154: int have_ssh1_key;
155: int have_ssh2_key;
1.169 markus 156: u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
1.1 deraadt 157: } sensitive_data;
158:
1.66 markus 159: /*
1.151 markus 160: * Flag indicating whether the RSA server key needs to be regenerated.
161: * Is set in the SIGALRM handler and cleared when the key is regenerated.
1.66 markus 162: */
1.151 markus 163: int key_do_regen = 0;
1.1 deraadt 164:
1.195.2.1 jason 165: /* This is set to true when a signal is received. */
1.1 deraadt 166: int received_sighup = 0;
1.195.2.1 jason 167: int received_sigterm = 0;
1.1 deraadt 168:
1.96 markus 169: /* session identifier, used by RSA-auth */
1.140 markus 170: u_char session_id[16];
1.96 markus 171:
1.108 markus 172: /* same for ssh2 */
1.140 markus 173: u_char *session_id2 = NULL;
1.108 markus 174: int session_id2_len = 0;
175:
1.125 markus 176: /* record remote hostname or ip */
1.140 markus 177: u_int utmp_len = MAXHOSTNAMELEN;
1.125 markus 178:
1.1 deraadt 179: /* Prototypes for various functions defined later in this file. */
1.195.2.1 jason 180: void destroy_sensitive_data(void);
1.87 markus 181:
1.195.2.1 jason 182: static void do_ssh1_kex(void);
183: static void do_ssh2_kex(void);
1.129 provos 184:
1.87 markus 185: /*
1.75 markus 186: * Close all listening sockets
187: */
1.195.2.1 jason 188: static void
1.75 markus 189: close_listen_socks(void)
190: {
191: int i;
192: for (i = 0; i < num_listen_socks; i++)
193: close(listen_socks[i]);
194: num_listen_socks = -1;
195: }
196:
197: /*
1.65 deraadt 198: * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
199: * the effect is to reread the configuration file (and to regenerate
200: * the server key).
201: */
1.195.2.1 jason 202: static void
1.64 markus 203: sighup_handler(int sig)
1.1 deraadt 204: {
1.64 markus 205: received_sighup = 1;
206: signal(SIGHUP, sighup_handler);
1.1 deraadt 207: }
208:
1.65 deraadt 209: /*
210: * Called from the main program after receiving SIGHUP.
211: * Restarts the server.
212: */
1.195.2.1 jason 213: static void
1.165 itojun 214: sighup_restart(void)
1.1 deraadt 215: {
1.64 markus 216: log("Received SIGHUP; restarting.");
1.75 markus 217: close_listen_socks();
1.64 markus 218: execv(saved_argv[0], saved_argv);
1.138 markus 219: log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno));
1.64 markus 220: exit(1);
1.1 deraadt 221: }
222:
1.65 deraadt 223: /*
224: * Generic signal handler for terminating signals in the master daemon.
225: */
1.195.2.1 jason 226: static void
1.64 markus 227: sigterm_handler(int sig)
1.1 deraadt 228: {
1.195.2.1 jason 229: received_sigterm = sig;
1.1 deraadt 230: }
231:
1.65 deraadt 232: /*
233: * SIGCHLD handler. This is called whenever a child dies. This will then
1.195.2.1 jason 234: * reap any zombies left by exited children.
1.65 deraadt 235: */
1.195.2.1 jason 236: static void
1.64 markus 237: main_sigchld_handler(int sig)
1.1 deraadt 238: {
1.64 markus 239: int save_errno = errno;
240: int status;
1.60 deraadt 241:
1.64 markus 242: while (waitpid(-1, &status, WNOHANG) > 0)
243: ;
1.60 deraadt 244:
1.64 markus 245: signal(SIGCHLD, main_sigchld_handler);
246: errno = save_errno;
1.1 deraadt 247: }
248:
1.65 deraadt 249: /*
250: * Signal handler for the alarm after the login grace period has expired.
251: */
1.195.2.1 jason 252: static void
1.64 markus 253: grace_alarm_handler(int sig)
1.1 deraadt 254: {
1.195.2.1 jason 255: /* XXX no idea how fix this signal handler */
256:
1.64 markus 257: /* Close the connection. */
258: packet_close();
259:
260: /* Log error and exit. */
261: fatal("Timeout before authentication for %s.", get_remote_ipaddr());
1.62 markus 262: }
263:
1.65 deraadt 264: /*
265: * Signal handler for the key regeneration alarm. Note that this
266: * alarm only occurs in the daemon waiting for connections, and it does not
267: * do anything with the private key or random state before forking.
268: * Thus there should be no concurrency control/asynchronous execution
269: * problems.
270: */
1.195.2.1 jason 271: static void
1.174 deraadt 272: generate_ephemeral_server_key(void)
1.134 markus 273: {
1.169 markus 274: u_int32_t rand = 0;
275: int i;
276:
1.191 markus 277: verbose("Generating %s%d bit RSA key.",
1.185 djm 278: sensitive_data.server_key ? "new " : "", options.server_key_bits);
1.134 markus 279: if (sensitive_data.server_key != NULL)
280: key_free(sensitive_data.server_key);
1.191 markus 281: sensitive_data.server_key = key_generate(KEY_RSA1,
1.185 djm 282: options.server_key_bits);
283: verbose("RSA key generation complete.");
1.169 markus 284:
285: for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
286: if (i % 4 == 0)
287: rand = arc4random();
288: sensitive_data.ssh1_cookie[i] = rand & 0xff;
289: rand >>= 8;
290: }
1.134 markus 291: arc4random_stir();
292: }
1.147 deraadt 293:
1.195.2.1 jason 294: static void
1.64 markus 295: key_regeneration_alarm(int sig)
1.1 deraadt 296: {
1.64 markus 297: int save_errno = errno;
1.151 markus 298: signal(SIGALRM, SIG_DFL);
1.64 markus 299: errno = save_errno;
1.151 markus 300: key_do_regen = 1;
1.98 markus 301: }
302:
1.195.2.1 jason 303: static void
1.96 markus 304: sshd_exchange_identification(int sock_in, int sock_out)
305: {
1.102 markus 306: int i, mismatch;
1.96 markus 307: int remote_major, remote_minor;
1.102 markus 308: int major, minor;
1.96 markus 309: char *s;
310: char buf[256]; /* Must not be larger than remote_version. */
311: char remote_version[256]; /* Must be at least as big as buf. */
312:
1.103 markus 313: if ((options.protocol & SSH_PROTO_1) &&
314: (options.protocol & SSH_PROTO_2)) {
1.102 markus 315: major = PROTOCOL_MAJOR_1;
316: minor = 99;
317: } else if (options.protocol & SSH_PROTO_2) {
318: major = PROTOCOL_MAJOR_2;
319: minor = PROTOCOL_MINOR_2;
320: } else {
321: major = PROTOCOL_MAJOR_1;
322: minor = PROTOCOL_MINOR_1;
323: }
324: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
1.96 markus 325: server_version_string = xstrdup(buf);
326:
327: if (client_version_string == NULL) {
328: /* Send our protocol version identification. */
329: if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
330: != strlen(server_version_string)) {
331: log("Could not write ident string to %s.", get_remote_ipaddr());
332: fatal_cleanup();
333: }
334:
1.167 markus 335: /* Read other side's version identification. */
1.191 markus 336: memset(buf, 0, sizeof(buf));
1.96 markus 337: for (i = 0; i < sizeof(buf) - 1; i++) {
1.119 markus 338: if (atomicio(read, sock_in, &buf[i], 1) != 1) {
1.168 deraadt 339: log("Did not receive identification string from %s.",
340: get_remote_ipaddr());
1.96 markus 341: fatal_cleanup();
342: }
343: if (buf[i] == '\r') {
1.176 deraadt 344: buf[i] = 0;
1.132 markus 345: /* Kludge for F-Secure Macintosh < 1.0.2 */
346: if (i == 12 &&
347: strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
348: break;
1.96 markus 349: continue;
350: }
351: if (buf[i] == '\n') {
1.176 deraadt 352: buf[i] = 0;
1.96 markus 353: break;
354: }
355: }
356: buf[sizeof(buf) - 1] = 0;
357: client_version_string = xstrdup(buf);
358: }
359:
360: /*
361: * Check that the versions match. In future this might accept
362: * several versions and set appropriate flags to handle them.
363: */
364: if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
365: &remote_major, &remote_minor, remote_version) != 3) {
1.105 markus 366: s = "Protocol mismatch.\n";
1.96 markus 367: (void) atomicio(write, sock_out, s, strlen(s));
368: close(sock_in);
369: close(sock_out);
370: log("Bad protocol version identification '%.100s' from %s",
371: client_version_string, get_remote_ipaddr());
372: fatal_cleanup();
373: }
374: debug("Client protocol version %d.%d; client software version %.100s",
375: remote_major, remote_minor, remote_version);
376:
1.98 markus 377: compat_datafellows(remote_version);
1.175 deraadt 378:
379: if (datafellows & SSH_BUG_SCANNER) {
380: log("scanned from %s with %s. Don't panic.",
381: get_remote_ipaddr(), client_version_string);
382: fatal_cleanup();
383: }
1.98 markus 384:
1.102 markus 385: mismatch = 0;
1.96 markus 386: switch(remote_major) {
387: case 1:
1.108 markus 388: if (remote_minor == 99) {
389: if (options.protocol & SSH_PROTO_2)
390: enable_compat20();
391: else
392: mismatch = 1;
393: break;
394: }
1.102 markus 395: if (!(options.protocol & SSH_PROTO_1)) {
396: mismatch = 1;
397: break;
398: }
1.96 markus 399: if (remote_minor < 3) {
1.121 provos 400: packet_disconnect("Your ssh version is too old and "
1.96 markus 401: "is no longer supported. Please install a newer version.");
402: } else if (remote_minor == 3) {
403: /* note that this disables agent-forwarding */
404: enable_compat13();
405: }
1.102 markus 406: break;
1.98 markus 407: case 2:
1.102 markus 408: if (options.protocol & SSH_PROTO_2) {
1.98 markus 409: enable_compat20();
410: break;
411: }
1.99 markus 412: /* FALLTHROUGH */
1.105 markus 413: default:
1.102 markus 414: mismatch = 1;
415: break;
416: }
417: chop(server_version_string);
418: debug("Local version string %.200s", server_version_string);
419:
420: if (mismatch) {
1.96 markus 421: s = "Protocol major versions differ.\n";
422: (void) atomicio(write, sock_out, s, strlen(s));
423: close(sock_in);
424: close(sock_out);
1.102 markus 425: log("Protocol major versions differ for %s: %.200s vs. %.200s",
426: get_remote_ipaddr(),
427: server_version_string, client_version_string);
1.96 markus 428: fatal_cleanup();
429: }
1.108 markus 430: }
431:
432:
1.134 markus 433: /* Destroy the host and server keys. They will no longer be needed. */
1.108 markus 434: void
435: destroy_sensitive_data(void)
436: {
1.134 markus 437: int i;
438:
439: if (sensitive_data.server_key) {
440: key_free(sensitive_data.server_key);
441: sensitive_data.server_key = NULL;
442: }
1.161 stevesk 443: for(i = 0; i < options.num_host_key_files; i++) {
1.134 markus 444: if (sensitive_data.host_keys[i]) {
445: key_free(sensitive_data.host_keys[i]);
446: sensitive_data.host_keys[i] = NULL;
447: }
448: }
449: sensitive_data.ssh1_host_key = NULL;
1.169 markus 450: memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
1.134 markus 451: }
452:
1.195.2.1 jason 453: static char *
1.134 markus 454: list_hostkey_types(void)
455: {
456: static char buf[1024];
457: int i;
458: buf[0] = '\0';
459: for(i = 0; i < options.num_host_key_files; i++) {
460: Key *key = sensitive_data.host_keys[i];
461: if (key == NULL)
462: continue;
463: switch(key->type) {
464: case KEY_RSA:
465: case KEY_DSA:
466: strlcat(buf, key_ssh_name(key), sizeof buf);
467: strlcat(buf, ",", sizeof buf);
468: break;
469: }
470: }
471: i = strlen(buf);
472: if (i > 0 && buf[i-1] == ',')
473: buf[i-1] = '\0';
474: debug("list_hostkey_types: %s", buf);
475: return buf;
476: }
477:
1.195.2.1 jason 478: static Key *
1.134 markus 479: get_hostkey_by_type(int type)
480: {
481: int i;
482: for(i = 0; i < options.num_host_key_files; i++) {
483: Key *key = sensitive_data.host_keys[i];
484: if (key != NULL && key->type == type)
485: return key;
486: }
487: return NULL;
1.96 markus 488: }
489:
1.124 markus 490: /*
491: * returns 1 if connection should be dropped, 0 otherwise.
492: * dropping starts at connection #max_startups_begin with a probability
493: * of (max_startups_rate/100). the probability increases linearly until
494: * all connections are dropped for startups > max_startups
495: */
1.195.2.1 jason 496: static int
1.124 markus 497: drop_connection(int startups)
498: {
499: double p, r;
500:
501: if (startups < options.max_startups_begin)
502: return 0;
503: if (startups >= options.max_startups)
504: return 1;
505: if (options.max_startups_rate == 100)
506: return 1;
507:
508: p = 100 - options.max_startups_rate;
509: p *= startups - options.max_startups_begin;
510: p /= (double) (options.max_startups - options.max_startups_begin);
511: p += options.max_startups_rate;
512: p /= 100.0;
513: r = arc4random() / (double) UINT_MAX;
514:
515: debug("drop_connection: p %g, r %g", p, r);
516: return (r < p) ? 1 : 0;
517: }
518:
1.120 markus 519: int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */
520: int startup_pipe; /* in child */
521:
1.65 deraadt 522: /*
523: * Main program for the daemon.
524: */
1.2 provos 525: int
526: main(int ac, char **av)
1.1 deraadt 527: {
1.64 markus 528: extern char *optarg;
529: extern int optind;
1.120 markus 530: int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
1.107 deraadt 531: pid_t pid;
1.75 markus 532: socklen_t fromlen;
533: fd_set *fdset;
534: struct sockaddr_storage from;
1.64 markus 535: const char *remote_ip;
536: int remote_port;
537: FILE *f;
538: struct linger linger;
1.75 markus 539: struct addrinfo *ai;
540: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
541: int listen_sock, maxfd;
1.120 markus 542: int startup_p[2];
543: int startups = 0;
1.179 markus 544: Key *key;
1.151 markus 545: int ret, key_used = 0;
1.64 markus 546:
1.138 markus 547: /* Save argv. */
1.64 markus 548: saved_argv = av;
549:
550: /* Initialize configuration options to their default values. */
551: initialize_server_options(&options);
552:
553: /* Parse command-line arguments. */
1.195.2.1 jason 554: while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:dDeiqtQ46")) != -1) {
1.64 markus 555: switch (opt) {
1.75 markus 556: case '4':
557: IPv4or6 = AF_INET;
558: break;
559: case '6':
560: IPv4or6 = AF_INET6;
561: break;
1.64 markus 562: case 'f':
563: config_file_name = optarg;
564: break;
565: case 'd':
1.127 markus 566: if (0 == debug_flag) {
567: debug_flag = 1;
568: options.log_level = SYSLOG_LEVEL_DEBUG1;
569: } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
570: options.log_level++;
571: } else {
572: fprintf(stderr, "Too high debugging level.\n");
573: exit(1);
574: }
1.64 markus 575: break;
1.135 markus 576: case 'D':
577: no_daemon_flag = 1;
1.192 lebel 578: break;
579: case 'e':
580: log_stderr = 1;
1.135 markus 581: break;
1.64 markus 582: case 'i':
583: inetd_flag = 1;
584: break;
585: case 'Q':
1.158 markus 586: /* ignored */
1.64 markus 587: break;
588: case 'q':
589: options.log_level = SYSLOG_LEVEL_QUIET;
590: break;
591: case 'b':
592: options.server_key_bits = atoi(optarg);
593: break;
594: case 'p':
1.75 markus 595: options.ports_from_cmdline = 1;
1.127 markus 596: if (options.num_ports >= MAX_PORTS) {
597: fprintf(stderr, "too many ports.\n");
598: exit(1);
599: }
1.193 stevesk 600: options.ports[options.num_ports++] = a2port(optarg);
601: if (options.ports[options.num_ports-1] == 0) {
602: fprintf(stderr, "Bad port number.\n");
603: exit(1);
604: }
1.64 markus 605: break;
606: case 'g':
1.195.2.1 jason 607: if ((options.login_grace_time = convtime(optarg)) == -1) {
608: fprintf(stderr, "Invalid login grace time.\n");
609: exit(1);
610: }
1.64 markus 611: break;
612: case 'k':
1.195.2.1 jason 613: if ((options.key_regeneration_time = convtime(optarg)) == -1) {
614: fprintf(stderr, "Invalid key regeneration interval.\n");
615: exit(1);
616: }
1.64 markus 617: break;
618: case 'h':
1.134 markus 619: if (options.num_host_key_files >= MAX_HOSTKEYS) {
620: fprintf(stderr, "too many host keys.\n");
621: exit(1);
622: }
623: options.host_key_files[options.num_host_key_files++] = optarg;
1.64 markus 624: break;
625: case 'V':
626: client_version_string = optarg;
627: /* only makes sense with inetd_flag, i.e. no listen() */
628: inetd_flag = 1;
629: break;
1.195.2.1 jason 630: case 't':
631: test_flag = 1;
632: break;
1.125 markus 633: case 'u':
634: utmp_len = atoi(optarg);
635: break;
1.64 markus 636: case '?':
637: default:
638: fprintf(stderr, "sshd version %s\n", SSH_VERSION);
1.138 markus 639: fprintf(stderr, "Usage: %s [options]\n", __progname);
1.64 markus 640: fprintf(stderr, "Options:\n");
1.154 markus 641: fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
1.127 markus 642: fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
1.64 markus 643: fprintf(stderr, " -i Started from inetd\n");
1.144 markus 644: fprintf(stderr, " -D Do not fork into daemon mode\n");
1.195.2.1 jason 645: fprintf(stderr, " -t Only test configuration file and keys\n");
1.64 markus 646: fprintf(stderr, " -q Quiet (no logging)\n");
647: fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
648: fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
1.145 markus 649: fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
1.64 markus 650: fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
651: fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
1.154 markus 652: _PATH_HOST_KEY_FILE);
1.125 markus 653: fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
1.75 markus 654: fprintf(stderr, " -4 Use IPv4 only\n");
655: fprintf(stderr, " -6 Use IPv6 only\n");
1.64 markus 656: exit(1);
657: }
658: }
1.180 markus 659: SSLeay_add_all_algorithms();
1.195.2.2! miod 660: channel_set_af(IPv4or6);
1.64 markus 661:
1.75 markus 662: /*
663: * Force logging to stderr until we have loaded the private host
664: * key (unless started from inetd)
665: */
1.138 markus 666: log_init(__progname,
1.152 markus 667: options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
1.75 markus 668: options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
1.158 markus 669: !inetd_flag);
1.75 markus 670:
1.64 markus 671: /* Read server configuration options from the configuration file. */
672: read_server_config(&options, config_file_name);
673:
674: /* Fill in default values for those options not explicitly set. */
675: fill_default_server_options(&options);
676:
677: /* Check that there are no remaining arguments. */
678: if (optind < ac) {
679: fprintf(stderr, "Extra argument %s.\n", av[optind]);
680: exit(1);
681: }
682:
683: debug("sshd version %.100s", SSH_VERSION);
684:
1.134 markus 685: /* load private host keys */
686: sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
1.141 markus 687: for(i = 0; i < options.num_host_key_files; i++)
688: sensitive_data.host_keys[i] = NULL;
1.134 markus 689: sensitive_data.server_key = NULL;
690: sensitive_data.ssh1_host_key = NULL;
691: sensitive_data.have_ssh1_key = 0;
692: sensitive_data.have_ssh2_key = 0;
693:
694: for(i = 0; i < options.num_host_key_files; i++) {
1.179 markus 695: key = key_load_private(options.host_key_files[i], "", NULL);
696: sensitive_data.host_keys[i] = key;
1.134 markus 697: if (key == NULL) {
1.195 markus 698: error("Could not load host key: %s",
699: options.host_key_files[i]);
1.179 markus 700: sensitive_data.host_keys[i] = NULL;
1.134 markus 701: continue;
702: }
703: switch(key->type){
704: case KEY_RSA1:
705: sensitive_data.ssh1_host_key = key;
706: sensitive_data.have_ssh1_key = 1;
707: break;
708: case KEY_RSA:
709: case KEY_DSA:
710: sensitive_data.have_ssh2_key = 1;
711: break;
712: }
1.179 markus 713: debug("private host key: #%d type %d %s", i, key->type,
714: key_type(key));
1.134 markus 715: }
716: if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
717: log("Disabling protocol version 1. Could not load host key");
1.108 markus 718: options.protocol &= ~SSH_PROTO_1;
719: }
1.134 markus 720: if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
721: log("Disabling protocol version 2. Could not load host key");
722: options.protocol &= ~SSH_PROTO_2;
1.108 markus 723: }
1.162 stevesk 724: if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1.172 millert 725: log("sshd: no hostkeys available -- exiting.");
1.64 markus 726: exit(1);
727: }
728:
1.108 markus 729: /* Check certain values for sanity. */
730: if (options.protocol & SSH_PROTO_1) {
731: if (options.server_key_bits < 512 ||
732: options.server_key_bits > 32768) {
733: fprintf(stderr, "Bad server key size.\n");
734: exit(1);
735: }
736: /*
737: * Check that server and host key lengths differ sufficiently. This
738: * is necessary to make double encryption work with rsaref. Oh, I
739: * hate software patents. I dont know if this can go? Niels
740: */
741: if (options.server_key_bits >
1.134 markus 742: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED &&
1.108 markus 743: options.server_key_bits <
1.134 markus 744: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1.108 markus 745: options.server_key_bits =
1.134 markus 746: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED;
1.108 markus 747: debug("Forcing server key to %d bits to make it differ from host key.",
748: options.server_key_bits);
749: }
750: }
751:
1.195.2.1 jason 752: /* Configuration looks good, so exit if in test mode. */
753: if (test_flag)
754: exit(0);
755:
1.108 markus 756: /* Initialize the log (it is reinitialized below in case we forked). */
1.64 markus 757: if (debug_flag && !inetd_flag)
758: log_stderr = 1;
1.138 markus 759: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.64 markus 760:
1.108 markus 761: /*
762: * If not in debugging mode, and not started from inetd, disconnect
763: * from the controlling terminal, and fork. The original process
764: * exits.
765: */
1.135 markus 766: if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1.1 deraadt 767: #ifdef TIOCNOTTY
1.64 markus 768: int fd;
1.1 deraadt 769: #endif /* TIOCNOTTY */
1.64 markus 770: if (daemon(0, 0) < 0)
771: fatal("daemon() failed: %.200s", strerror(errno));
772:
773: /* Disconnect from the controlling tty. */
1.1 deraadt 774: #ifdef TIOCNOTTY
1.165 itojun 775: fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1.64 markus 776: if (fd >= 0) {
777: (void) ioctl(fd, TIOCNOTTY, NULL);
778: close(fd);
779: }
780: #endif /* TIOCNOTTY */
781: }
782: /* Reinitialize the log (because of the fork above). */
1.138 markus 783: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.64 markus 784:
785: /* Initialize the random number generator. */
786: arc4random_stir();
787:
788: /* Chdir to the root directory so that the current disk can be
789: unmounted if desired. */
790: chdir("/");
1.178 markus 791:
792: /* ignore SIGPIPE */
793: signal(SIGPIPE, SIG_IGN);
1.64 markus 794:
795: /* Start listening for a socket, unless started from inetd. */
796: if (inetd_flag) {
1.194 markus 797: int s1;
1.64 markus 798: s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
1.194 markus 799: dup(s1);
1.64 markus 800: sock_in = dup(0);
801: sock_out = dup(1);
1.123 djm 802: startup_pipe = -1;
1.108 markus 803: /*
804: * We intentionally do not close the descriptors 0, 1, and 2
805: * as our code for setting the descriptors won\'t work if
806: * ttyfd happens to be one of those.
807: */
1.64 markus 808: debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1.134 markus 809: if (options.protocol & SSH_PROTO_1)
1.174 deraadt 810: generate_ephemeral_server_key();
1.64 markus 811: } else {
1.75 markus 812: for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
813: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
814: continue;
815: if (num_listen_socks >= MAX_LISTEN_SOCKS)
816: fatal("Too many listen sockets. "
817: "Enlarge MAX_LISTEN_SOCKS");
818: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
819: ntop, sizeof(ntop), strport, sizeof(strport),
820: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
821: error("getnameinfo failed");
822: continue;
823: }
824: /* Create socket for listening. */
825: listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
826: if (listen_sock < 0) {
827: /* kernel may not support ipv6 */
828: verbose("socket: %.100s", strerror(errno));
829: continue;
830: }
831: if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
832: error("listen_sock O_NONBLOCK: %s", strerror(errno));
833: close(listen_sock);
834: continue;
835: }
836: /*
837: * Set socket options. We try to make the port
838: * reusable and have it close as fast as possible
839: * without waiting in unnecessary wait states on
840: * close.
841: */
842: setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
843: (void *) &on, sizeof(on));
844: linger.l_onoff = 1;
845: linger.l_linger = 5;
846: setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
847: (void *) &linger, sizeof(linger));
848:
849: debug("Bind to port %s on %s.", strport, ntop);
850:
851: /* Bind the socket to the desired port. */
852: if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
853: error("Bind to port %s on %s failed: %.200s.",
854: strport, ntop, strerror(errno));
855: close(listen_sock);
856: continue;
857: }
858: listen_socks[num_listen_socks] = listen_sock;
859: num_listen_socks++;
860:
861: /* Start listening on the port. */
862: log("Server listening on %s port %s.", ntop, strport);
863: if (listen(listen_sock, 5) < 0)
864: fatal("listen: %.100s", strerror(errno));
865:
1.64 markus 866: }
1.75 markus 867: freeaddrinfo(options.listen_addrs);
868:
869: if (!num_listen_socks)
870: fatal("Cannot bind any address.");
871:
1.195.2.1 jason 872: if (options.protocol & SSH_PROTO_1)
873: generate_ephemeral_server_key();
874:
875: /*
876: * Arrange to restart on SIGHUP. The handler needs
877: * listen_sock.
878: */
879: signal(SIGHUP, sighup_handler);
880:
881: signal(SIGTERM, sigterm_handler);
882: signal(SIGQUIT, sigterm_handler);
883:
884: /* Arrange SIGCHLD to be caught. */
885: signal(SIGCHLD, main_sigchld_handler);
886:
887: /* Write out the pid file after the sigterm handler is setup */
1.64 markus 888: if (!debug_flag) {
1.66 markus 889: /*
1.136 todd 890: * Record our pid in /var/run/sshd.pid to make it
891: * easier to kill the correct sshd. We don't want to
892: * do this before the bind above because the bind will
1.66 markus 893: * fail if there already is a daemon, and this will
894: * overwrite any old pid in the file.
895: */
1.112 markus 896: f = fopen(options.pid_file, "w");
1.64 markus 897: if (f) {
1.140 markus 898: fprintf(f, "%u\n", (u_int) getpid());
1.64 markus 899: fclose(f);
900: }
901: }
902:
1.75 markus 903: /* setup fd set for listen */
1.120 markus 904: fdset = NULL;
1.75 markus 905: maxfd = 0;
906: for (i = 0; i < num_listen_socks; i++)
907: if (listen_socks[i] > maxfd)
908: maxfd = listen_socks[i];
1.120 markus 909: /* pipes connected to unauthenticated childs */
910: startup_pipes = xmalloc(options.max_startups * sizeof(int));
911: for (i = 0; i < options.max_startups; i++)
912: startup_pipes[i] = -1;
1.75 markus 913:
1.66 markus 914: /*
915: * Stay listening for connections until the system crashes or
916: * the daemon is killed with a signal.
917: */
1.64 markus 918: for (;;) {
919: if (received_sighup)
920: sighup_restart();
1.120 markus 921: if (fdset != NULL)
922: xfree(fdset);
1.148 markus 923: fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1.120 markus 924: fdset = (fd_set *)xmalloc(fdsetsz);
1.75 markus 925: memset(fdset, 0, fdsetsz);
1.120 markus 926:
1.75 markus 927: for (i = 0; i < num_listen_socks; i++)
928: FD_SET(listen_socks[i], fdset);
1.120 markus 929: for (i = 0; i < options.max_startups; i++)
930: if (startup_pipes[i] != -1)
931: FD_SET(startup_pipes[i], fdset);
932:
933: /* Wait in select until there is a connection. */
1.151 markus 934: ret = select(maxfd+1, fdset, NULL, NULL, NULL);
935: if (ret < 0 && errno != EINTR)
936: error("select: %.100s", strerror(errno));
1.195.2.1 jason 937: if (received_sigterm) {
938: log("Received signal %d; terminating.",
939: received_sigterm);
940: close_listen_socks();
941: unlink(options.pid_file);
942: exit(255);
943: }
1.151 markus 944: if (key_used && key_do_regen) {
1.174 deraadt 945: generate_ephemeral_server_key();
1.151 markus 946: key_used = 0;
947: key_do_regen = 0;
948: }
949: if (ret < 0)
1.75 markus 950: continue;
1.151 markus 951:
1.120 markus 952: for (i = 0; i < options.max_startups; i++)
953: if (startup_pipes[i] != -1 &&
954: FD_ISSET(startup_pipes[i], fdset)) {
955: /*
956: * the read end of the pipe is ready
957: * if the child has closed the pipe
1.143 markus 958: * after successful authentication
1.120 markus 959: * or if the child has died
960: */
961: close(startup_pipes[i]);
962: startup_pipes[i] = -1;
963: startups--;
964: }
1.75 markus 965: for (i = 0; i < num_listen_socks; i++) {
966: if (!FD_ISSET(listen_socks[i], fdset))
1.70 provos 967: continue;
1.120 markus 968: fromlen = sizeof(from);
969: newsock = accept(listen_socks[i], (struct sockaddr *)&from,
970: &fromlen);
971: if (newsock < 0) {
972: if (errno != EINTR && errno != EWOULDBLOCK)
973: error("accept: %.100s", strerror(errno));
974: continue;
975: }
976: if (fcntl(newsock, F_SETFL, 0) < 0) {
977: error("newsock del O_NONBLOCK: %s", strerror(errno));
978: continue;
979: }
1.124 markus 980: if (drop_connection(startups) == 1) {
981: debug("drop connection #%d", startups);
1.120 markus 982: close(newsock);
983: continue;
984: }
985: if (pipe(startup_p) == -1) {
986: close(newsock);
987: continue;
988: }
989:
990: for (j = 0; j < options.max_startups; j++)
991: if (startup_pipes[j] == -1) {
992: startup_pipes[j] = startup_p[0];
993: if (maxfd < startup_p[0])
994: maxfd = startup_p[0];
995: startups++;
996: break;
997: }
1.161 stevesk 998:
1.66 markus 999: /*
1.120 markus 1000: * Got connection. Fork a child to handle it, unless
1001: * we are in debugging mode.
1.66 markus 1002: */
1.120 markus 1003: if (debug_flag) {
1.66 markus 1004: /*
1.120 markus 1005: * In debugging mode. Close the listening
1006: * socket, and start processing the
1007: * connection without forking.
1.66 markus 1008: */
1.120 markus 1009: debug("Server will not fork when running in debugging mode.");
1.75 markus 1010: close_listen_socks();
1.64 markus 1011: sock_in = newsock;
1012: sock_out = newsock;
1.122 deraadt 1013: startup_pipe = -1;
1.120 markus 1014: pid = getpid();
1.64 markus 1015: break;
1.120 markus 1016: } else {
1017: /*
1018: * Normal production daemon. Fork, and have
1019: * the child process the connection. The
1020: * parent continues listening.
1021: */
1022: if ((pid = fork()) == 0) {
1023: /*
1024: * Child. Close the listening and max_startup
1025: * sockets. Start using the accepted socket.
1026: * Reinitialize logging (since our pid has
1027: * changed). We break out of the loop to handle
1028: * the connection.
1029: */
1030: startup_pipe = startup_p[1];
1031: for (j = 0; j < options.max_startups; j++)
1032: if (startup_pipes[j] != -1)
1033: close(startup_pipes[j]);
1034: close_listen_socks();
1035: sock_in = newsock;
1036: sock_out = newsock;
1.138 markus 1037: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.120 markus 1038: break;
1039: }
1.64 markus 1040: }
1041:
1.120 markus 1042: /* Parent. Stay in the loop. */
1043: if (pid < 0)
1044: error("fork: %.100s", strerror(errno));
1045: else
1046: debug("Forked child %d.", pid);
1047:
1048: close(startup_p[1]);
1.1 deraadt 1049:
1.120 markus 1050: /* Mark that the key has been used (it was "given" to the child). */
1.151 markus 1051: if ((options.protocol & SSH_PROTO_1) &&
1052: key_used == 0) {
1053: /* Schedule server key regeneration alarm. */
1054: signal(SIGALRM, key_regeneration_alarm);
1055: alarm(options.key_regeneration_time);
1056: key_used = 1;
1057: }
1.1 deraadt 1058:
1.120 markus 1059: arc4random_stir();
1.1 deraadt 1060:
1.120 markus 1061: /* Close the new socket (the child is now taking care of it). */
1062: close(newsock);
1063: }
1.75 markus 1064: /* child process check (or debug mode) */
1065: if (num_listen_socks < 0)
1066: break;
1.64 markus 1067: }
1.1 deraadt 1068: }
1069:
1.64 markus 1070: /* This is the child processing a new connection. */
1071:
1.66 markus 1072: /*
1073: * Disable the key regeneration alarm. We will not regenerate the
1074: * key since we are no longer in a position to give it to anyone. We
1075: * will not restart on SIGHUP since it no longer makes sense.
1076: */
1.64 markus 1077: alarm(0);
1078: signal(SIGALRM, SIG_DFL);
1079: signal(SIGHUP, SIG_DFL);
1080: signal(SIGTERM, SIG_DFL);
1081: signal(SIGQUIT, SIG_DFL);
1082: signal(SIGCHLD, SIG_DFL);
1083:
1.66 markus 1084: /*
1085: * Set socket options for the connection. We want the socket to
1086: * close as fast as possible without waiting for anything. If the
1087: * connection is not a socket, these will do nothing.
1088: */
1089: /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.64 markus 1090: linger.l_onoff = 1;
1091: linger.l_linger = 5;
1092: setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
1.150 markus 1093:
1094: /* Set keepalives if requested. */
1095: if (options.keepalives &&
1096: setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1097: sizeof(on)) < 0)
1098: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.64 markus 1099:
1.66 markus 1100: /*
1101: * Register our connection. This turns encryption off because we do
1102: * not have a key.
1103: */
1.64 markus 1104: packet_set_connection(sock_in, sock_out);
1.1 deraadt 1105:
1.64 markus 1106: remote_port = get_remote_port();
1107: remote_ip = get_remote_ipaddr();
1.52 markus 1108:
1.64 markus 1109: /* Check whether logins are denied from this host. */
1.37 dugsong 1110: #ifdef LIBWRAP
1.75 markus 1111: /* XXX LIBWRAP noes not know about IPv6 */
1.64 markus 1112: {
1113: struct request_info req;
1.37 dugsong 1114:
1.195.2.1 jason 1115: request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, 0);
1.64 markus 1116: fromhost(&req);
1.37 dugsong 1117:
1.64 markus 1118: if (!hosts_access(&req)) {
1.182 markus 1119: refuse(&req);
1.64 markus 1120: close(sock_in);
1121: close(sock_out);
1122: }
1.75 markus 1123: /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */
1.64 markus 1124: }
1.75 markus 1125: #endif /* LIBWRAP */
1.64 markus 1126: /* Log the connection. */
1127: verbose("Connection from %.500s port %d", remote_ip, remote_port);
1.1 deraadt 1128:
1.66 markus 1129: /*
1130: * We don\'t want to listen forever unless the other side
1131: * successfully authenticates itself. So we set up an alarm which is
1132: * cleared after successful authentication. A limit of zero
1133: * indicates no limit. Note that we don\'t set the alarm in debugging
1134: * mode; it is just annoying to have the server exit just when you
1135: * are about to discover the bug.
1136: */
1.64 markus 1137: signal(SIGALRM, grace_alarm_handler);
1138: if (!debug_flag)
1139: alarm(options.login_grace_time);
1140:
1.96 markus 1141: sshd_exchange_identification(sock_in, sock_out);
1.66 markus 1142: /*
1.137 markus 1143: * Check that the connection comes from a privileged port.
1144: * Rhosts-Authentication only makes sense from priviledged
1.66 markus 1145: * programs. Of course, if the intruder has root access on his local
1146: * machine, he can connect from any port. So do not use these
1147: * authentication methods from machines that you do not trust.
1148: */
1.64 markus 1149: if (remote_port >= IPPORT_RESERVED ||
1150: remote_port < IPPORT_RESERVED / 2) {
1.137 markus 1151: debug("Rhosts Authentication disabled, "
1.133 markus 1152: "originating port not trusted.");
1.64 markus 1153: options.rhosts_authentication = 0;
1154: }
1.195.2.1 jason 1155: #if defined(KRB4) && !defined(KRB5)
1.76 markus 1156: if (!packet_connection_is_ipv4() &&
1157: options.kerberos_authentication) {
1158: debug("Kerberos Authentication disabled, only available for IPv4.");
1159: options.kerberos_authentication = 0;
1160: }
1.195.2.1 jason 1161: #endif /* KRB4 && !KRB5 */
1.164 markus 1162: #ifdef AFS
1163: /* If machine has AFS, set process authentication group. */
1164: if (k_hasafs()) {
1165: k_setpag();
1166: k_unlog();
1167: }
1168: #endif /* AFS */
1.76 markus 1169:
1.64 markus 1170: packet_set_nonblocking();
1.1 deraadt 1171:
1.77 markus 1172: /* perform the key exchange */
1173: /* authenticate user and start session */
1.98 markus 1174: if (compat20) {
1175: do_ssh2_kex();
1176: do_authentication2();
1177: } else {
1178: do_ssh1_kex();
1179: do_authentication();
1180: }
1.64 markus 1181: /* The connection has been terminated. */
1182: verbose("Closing connection to %.100s", remote_ip);
1183: packet_close();
1184: exit(0);
1.1 deraadt 1185: }
1186:
1.65 deraadt 1187: /*
1.77 markus 1188: * SSH1 key exchange
1.65 deraadt 1189: */
1.195.2.1 jason 1190: static void
1.142 markus 1191: do_ssh1_kex(void)
1.1 deraadt 1192: {
1.64 markus 1193: int i, len;
1.77 markus 1194: int plen, slen;
1.159 markus 1195: int rsafail = 0;
1.64 markus 1196: BIGNUM *session_key_int;
1.140 markus 1197: u_char session_key[SSH_SESSION_KEY_LENGTH];
1198: u_char cookie[8];
1199: u_int cipher_type, auth_mask, protocol_flags;
1.64 markus 1200: u_int32_t rand = 0;
1201:
1.66 markus 1202: /*
1203: * Generate check bytes that the client must send back in the user
1204: * packet in order for it to be accepted; this is used to defy ip
1205: * spoofing attacks. Note that this only works against somebody
1206: * doing IP spoofing from a remote machine; any machine on the local
1207: * network can still see outgoing packets and catch the random
1208: * cookie. This only affects rhosts authentication, and this is one
1209: * of the reasons why it is inherently insecure.
1210: */
1.64 markus 1211: for (i = 0; i < 8; i++) {
1212: if (i % 4 == 0)
1213: rand = arc4random();
1.77 markus 1214: cookie[i] = rand & 0xff;
1.64 markus 1215: rand >>= 8;
1216: }
1217:
1.66 markus 1218: /*
1219: * Send our public key. We include in the packet 64 bits of random
1220: * data that must be matched in the reply in order to prevent IP
1221: * spoofing.
1222: */
1.64 markus 1223: packet_start(SSH_SMSG_PUBLIC_KEY);
1224: for (i = 0; i < 8; i++)
1.77 markus 1225: packet_put_char(cookie[i]);
1.64 markus 1226:
1227: /* Store our public server RSA key. */
1.134 markus 1228: packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1229: packet_put_bignum(sensitive_data.server_key->rsa->e);
1230: packet_put_bignum(sensitive_data.server_key->rsa->n);
1.64 markus 1231:
1232: /* Store our public host RSA key. */
1.134 markus 1233: packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1234: packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1235: packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1.64 markus 1236:
1237: /* Put protocol flags. */
1238: packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1239:
1240: /* Declare which ciphers we support. */
1.131 markus 1241: packet_put_int(cipher_mask_ssh1(0));
1.64 markus 1242:
1243: /* Declare supported authentication types. */
1244: auth_mask = 0;
1245: if (options.rhosts_authentication)
1246: auth_mask |= 1 << SSH_AUTH_RHOSTS;
1247: if (options.rhosts_rsa_authentication)
1248: auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1249: if (options.rsa_authentication)
1250: auth_mask |= 1 << SSH_AUTH_RSA;
1.195.2.1 jason 1251: #if defined(KRB4) || defined(KRB5)
1.64 markus 1252: if (options.kerberos_authentication)
1253: auth_mask |= 1 << SSH_AUTH_KERBEROS;
1.1 deraadt 1254: #endif
1.195.2.1 jason 1255: #if defined(AFS) || defined(KRB5)
1.64 markus 1256: if (options.kerberos_tgt_passing)
1257: auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
1.195.2.1 jason 1258: #endif
1259: #ifdef AFS
1.64 markus 1260: if (options.afs_token_passing)
1261: auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
1.1 deraadt 1262: #endif
1.195.2.1 jason 1263: if (options.challenge_response_authentication == 1)
1.64 markus 1264: auth_mask |= 1 << SSH_AUTH_TIS;
1265: if (options.password_authentication)
1266: auth_mask |= 1 << SSH_AUTH_PASSWORD;
1267: packet_put_int(auth_mask);
1268:
1269: /* Send the packet and wait for it to be sent. */
1270: packet_send();
1271: packet_write_wait();
1272:
1.134 markus 1273: debug("Sent %d bit server key and %d bit host key.",
1274: BN_num_bits(sensitive_data.server_key->rsa->n),
1275: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1.64 markus 1276:
1277: /* Read clients reply (cipher type and session key). */
1278: packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
1279:
1.69 markus 1280: /* Get cipher type and check whether we accept this. */
1.64 markus 1281: cipher_type = packet_get_char();
1.69 markus 1282:
1.131 markus 1283: if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1.69 markus 1284: packet_disconnect("Warning: client selects unsupported cipher.");
1.64 markus 1285:
1286: /* Get check bytes from the packet. These must match those we
1287: sent earlier with the public key packet. */
1288: for (i = 0; i < 8; i++)
1.77 markus 1289: if (cookie[i] != packet_get_char())
1.64 markus 1290: packet_disconnect("IP Spoofing check bytes do not match.");
1291:
1292: debug("Encryption type: %.200s", cipher_name(cipher_type));
1293:
1294: /* Get the encrypted integer. */
1295: session_key_int = BN_new();
1296: packet_get_bignum(session_key_int, &slen);
1297:
1298: protocol_flags = packet_get_int();
1299: packet_set_protocol_flags(protocol_flags);
1300:
1301: packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
1302:
1.66 markus 1303: /*
1304: * Decrypt it using our private server key and private host key (key
1305: * with larger modulus first).
1306: */
1.134 markus 1307: if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1.159 markus 1308: /* Server key has bigger modulus. */
1.134 markus 1309: if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1310: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1311: fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1312: get_remote_ipaddr(),
1313: BN_num_bits(sensitive_data.server_key->rsa->n),
1314: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1315: SSH_KEY_BITS_RESERVED);
1.64 markus 1316: }
1.159 markus 1317: if (rsa_private_decrypt(session_key_int, session_key_int,
1318: sensitive_data.server_key->rsa) <= 0)
1319: rsafail++;
1320: if (rsa_private_decrypt(session_key_int, session_key_int,
1321: sensitive_data.ssh1_host_key->rsa) <= 0)
1322: rsafail++;
1.64 markus 1323: } else {
1324: /* Host key has bigger modulus (or they are equal). */
1.134 markus 1325: if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1326: BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1327: fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1328: get_remote_ipaddr(),
1329: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1330: BN_num_bits(sensitive_data.server_key->rsa->n),
1331: SSH_KEY_BITS_RESERVED);
1.64 markus 1332: }
1.159 markus 1333: if (rsa_private_decrypt(session_key_int, session_key_int,
1334: sensitive_data.ssh1_host_key->rsa) < 0)
1335: rsafail++;
1336: if (rsa_private_decrypt(session_key_int, session_key_int,
1337: sensitive_data.server_key->rsa) < 0)
1338: rsafail++;
1.64 markus 1339: }
1.66 markus 1340: /*
1341: * Extract session key from the decrypted integer. The key is in the
1342: * least significant 256 bits of the integer; the first byte of the
1343: * key is in the highest bits.
1344: */
1.159 markus 1345: if (!rsafail) {
1346: BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1347: len = BN_num_bytes(session_key_int);
1348: if (len < 0 || len > sizeof(session_key)) {
1349: error("do_connection: bad session key len from %s: "
1.165 itojun 1350: "session_key_int %d > sizeof(session_key) %lu",
1351: get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1.159 markus 1352: rsafail++;
1353: } else {
1354: memset(session_key, 0, sizeof(session_key));
1355: BN_bn2bin(session_key_int,
1356: session_key + sizeof(session_key) - len);
1.169 markus 1357:
1358: compute_session_id(session_id, cookie,
1359: sensitive_data.ssh1_host_key->rsa->n,
1360: sensitive_data.server_key->rsa->n);
1361: /*
1362: * Xor the first 16 bytes of the session key with the
1363: * session id.
1364: */
1365: for (i = 0; i < 16; i++)
1366: session_key[i] ^= session_id[i];
1.159 markus 1367: }
1368: }
1369: if (rsafail) {
1.169 markus 1370: int bytes = BN_num_bytes(session_key_int);
1371: char *buf = xmalloc(bytes);
1372: MD5_CTX md;
1373:
1.159 markus 1374: log("do_connection: generating a fake encryption key");
1.169 markus 1375: BN_bn2bin(session_key_int, buf);
1376: MD5_Init(&md);
1377: MD5_Update(&md, buf, bytes);
1378: MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1379: MD5_Final(session_key, &md);
1380: MD5_Init(&md);
1381: MD5_Update(&md, session_key, 16);
1382: MD5_Update(&md, buf, bytes);
1383: MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1384: MD5_Final(session_key + 16, &md);
1385: memset(buf, 0, bytes);
1386: xfree(buf);
1.170 markus 1387: for (i = 0; i < 16; i++)
1388: session_id[i] = session_key[i] ^ session_key[i + 16];
1.159 markus 1389: }
1.169 markus 1390: /* Destroy the private and public keys. They will no longer be needed. */
1391: destroy_sensitive_data();
1392:
1.77 markus 1393: /* Destroy the decrypted integer. It is no longer needed. */
1394: BN_clear_free(session_key_int);
1.64 markus 1395:
1396: /* Set the session key. From this on all communications will be encrypted. */
1397: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1398:
1399: /* Destroy our copy of the session key. It is no longer needed. */
1400: memset(session_key, 0, sizeof(session_key));
1401:
1402: debug("Received session key; encryption turned on.");
1403:
1404: /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1405: packet_start(SSH_SMSG_SUCCESS);
1406: packet_send();
1407: packet_write_wait();
1.98 markus 1408: }
1409:
1410: /*
1411: * SSH2 key exchange: diffie-hellman-group1-sha1
1412: */
1.195.2.1 jason 1413: static void
1.142 markus 1414: do_ssh2_kex(void)
1.98 markus 1415: {
1416: Kex *kex;
1.102 markus 1417:
1418: if (options.ciphers != NULL) {
1.105 markus 1419: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1.102 markus 1420: myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1.166 markus 1421: }
1.184 stevesk 1422: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1423: compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_CTOS]);
1424: myproposal[PROPOSAL_ENC_ALGS_STOC] =
1425: compat_cipher_proposal(myproposal[PROPOSAL_ENC_ALGS_STOC]);
1426:
1.166 markus 1427: if (options.macs != NULL) {
1428: myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1429: myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1.102 markus 1430: }
1.134 markus 1431: myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1432:
1.189 markus 1433: /* start key exchange */
1.188 markus 1434: kex = kex_setup(myproposal);
1.186 markus 1435: kex->server = 1;
1436: kex->client_version_string=client_version_string;
1437: kex->server_version_string=server_version_string;
1438: kex->load_host_key=&get_hostkey_by_type;
1.129 provos 1439:
1.189 markus 1440: xxx_kex = kex;
1441:
1.190 markus 1442: dispatch_run(DISPATCH_BLOCK, &kex->done, kex);
1.187 markus 1443:
1444: session_id2 = kex->session_id;
1445: session_id2_len = kex->session_id_len;
1.129 provos 1446:
1447: #ifdef DEBUG_KEXDH
1448: /* send 1st encrypted/maced/compressed message */
1449: packet_start(SSH2_MSG_IGNORE);
1450: packet_put_cstring("markus");
1451: packet_send();
1452: packet_write_wait();
1453: #endif
1.186 markus 1454: debug("KEX done");
1.1 deraadt 1455: }
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