Annotation of src/usr.bin/ssh/sshd.c, Revision 1.175
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"
1.175 ! deraadt 43: RCSID("$OpenBSD: sshd.c,v 1.174 2001/03/09 12:30:29 deraadt 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"
1.1 deraadt 73:
74: #ifdef LIBWRAP
75: #include <tcpd.h>
76: #include <syslog.h>
77: int allow_severity = LOG_INFO;
78: int deny_severity = LOG_WARNING;
79: #endif /* LIBWRAP */
80:
81: #ifndef O_NOCTTY
82: #define O_NOCTTY 0
83: #endif
84:
1.138 markus 85: extern char *__progname;
86:
1.1 deraadt 87: /* Server configuration options. */
88: ServerOptions options;
89:
90: /* Name of the server configuration file. */
1.154 markus 91: char *config_file_name = _PATH_SERVER_CONFIG_FILE;
1.1 deraadt 92:
1.105 markus 93: /*
1.75 markus 94: * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
95: * Default value is AF_UNSPEC means both IPv4 and IPv6.
96: */
97: int IPv4or6 = AF_UNSPEC;
98:
1.65 deraadt 99: /*
100: * Debug mode flag. This can be set on the command line. If debug
101: * mode is enabled, extra debugging output will be sent to the system
102: * log, the daemon will not go to background, and will exit after processing
103: * the first connection.
104: */
1.1 deraadt 105: int debug_flag = 0;
106:
107: /* Flag indicating that the daemon is being started from inetd. */
108: int inetd_flag = 0;
109:
1.135 markus 110: /* Flag indicating that sshd should not detach and become a daemon. */
111: int no_daemon_flag = 0;
112:
1.47 markus 113: /* debug goes to stderr unless inetd_flag is set */
114: int log_stderr = 0;
115:
1.1 deraadt 116: /* Saved arguments to main(). */
117: char **saved_argv;
118:
1.66 markus 119: /*
1.75 markus 120: * The sockets that the server is listening; this is used in the SIGHUP
121: * signal handler.
1.66 markus 122: */
1.75 markus 123: #define MAX_LISTEN_SOCKS 16
124: int listen_socks[MAX_LISTEN_SOCKS];
125: int num_listen_socks = 0;
1.1 deraadt 126:
1.66 markus 127: /*
128: * the client's version string, passed by sshd2 in compat mode. if != NULL,
129: * sshd will skip the version-number exchange
130: */
1.61 markus 131: char *client_version_string = NULL;
1.96 markus 132: char *server_version_string = NULL;
1.1 deraadt 133:
1.66 markus 134: /*
135: * Any really sensitive data in the application is contained in this
136: * structure. The idea is that this structure could be locked into memory so
137: * that the pages do not get written into swap. However, there are some
138: * problems. The private key contains BIGNUMs, and we do not (in principle)
139: * have access to the internals of them, and locking just the structure is
140: * not very useful. Currently, memory locking is not implemented.
141: */
1.64 markus 142: struct {
1.174 deraadt 143: Key *server_key; /* ephemeral server key */
1.134 markus 144: Key *ssh1_host_key; /* ssh1 host key */
145: Key **host_keys; /* all private host keys */
146: int have_ssh1_key;
147: int have_ssh2_key;
1.169 markus 148: u_char ssh1_cookie[SSH_SESSION_KEY_LENGTH];
1.1 deraadt 149: } sensitive_data;
150:
1.66 markus 151: /*
1.151 markus 152: * Flag indicating whether the RSA server key needs to be regenerated.
153: * Is set in the SIGALRM handler and cleared when the key is regenerated.
1.66 markus 154: */
1.151 markus 155: int key_do_regen = 0;
1.1 deraadt 156:
157: /* This is set to true when SIGHUP is received. */
158: int received_sighup = 0;
159:
1.96 markus 160: /* session identifier, used by RSA-auth */
1.140 markus 161: u_char session_id[16];
1.96 markus 162:
1.108 markus 163: /* same for ssh2 */
1.140 markus 164: u_char *session_id2 = NULL;
1.108 markus 165: int session_id2_len = 0;
166:
1.125 markus 167: /* record remote hostname or ip */
1.140 markus 168: u_int utmp_len = MAXHOSTNAMELEN;
1.125 markus 169:
1.1 deraadt 170: /* Prototypes for various functions defined later in this file. */
1.142 markus 171: void do_ssh1_kex(void);
172: void do_ssh2_kex(void);
1.87 markus 173:
1.129 provos 174: void ssh_dh1_server(Kex *, Buffer *_kexinit, Buffer *);
175: void ssh_dhgex_server(Kex *, Buffer *_kexinit, Buffer *);
176:
1.87 markus 177: /*
1.75 markus 178: * Close all listening sockets
179: */
180: void
181: close_listen_socks(void)
182: {
183: int i;
184: for (i = 0; i < num_listen_socks; i++)
185: close(listen_socks[i]);
186: num_listen_socks = -1;
187: }
188:
189: /*
1.65 deraadt 190: * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
191: * the effect is to reread the configuration file (and to regenerate
192: * the server key).
193: */
1.105 markus 194: void
1.64 markus 195: sighup_handler(int sig)
1.1 deraadt 196: {
1.64 markus 197: received_sighup = 1;
198: signal(SIGHUP, sighup_handler);
1.1 deraadt 199: }
200:
1.65 deraadt 201: /*
202: * Called from the main program after receiving SIGHUP.
203: * Restarts the server.
204: */
1.105 markus 205: void
1.165 itojun 206: sighup_restart(void)
1.1 deraadt 207: {
1.64 markus 208: log("Received SIGHUP; restarting.");
1.75 markus 209: close_listen_socks();
1.64 markus 210: execv(saved_argv[0], saved_argv);
1.138 markus 211: log("RESTART FAILED: av[0]='%.100s', error: %.100s.", saved_argv[0], strerror(errno));
1.64 markus 212: exit(1);
1.1 deraadt 213: }
214:
1.65 deraadt 215: /*
216: * Generic signal handler for terminating signals in the master daemon.
217: * These close the listen socket; not closing it seems to cause "Address
218: * already in use" problems on some machines, which is inconvenient.
219: */
1.105 markus 220: void
1.64 markus 221: sigterm_handler(int sig)
1.1 deraadt 222: {
1.64 markus 223: log("Received signal %d; terminating.", sig);
1.75 markus 224: close_listen_socks();
1.113 markus 225: unlink(options.pid_file);
1.64 markus 226: exit(255);
1.1 deraadt 227: }
228:
1.65 deraadt 229: /*
230: * SIGCHLD handler. This is called whenever a child dies. This will then
231: * reap any zombies left by exited c.
232: */
1.105 markus 233: void
1.64 markus 234: main_sigchld_handler(int sig)
1.1 deraadt 235: {
1.64 markus 236: int save_errno = errno;
237: int status;
1.60 deraadt 238:
1.64 markus 239: while (waitpid(-1, &status, WNOHANG) > 0)
240: ;
1.60 deraadt 241:
1.64 markus 242: signal(SIGCHLD, main_sigchld_handler);
243: errno = save_errno;
1.1 deraadt 244: }
245:
1.65 deraadt 246: /*
247: * Signal handler for the alarm after the login grace period has expired.
248: */
1.105 markus 249: void
1.64 markus 250: grace_alarm_handler(int sig)
1.1 deraadt 251: {
1.64 markus 252: /* Close the connection. */
253: packet_close();
254:
255: /* Log error and exit. */
256: fatal("Timeout before authentication for %s.", get_remote_ipaddr());
1.62 markus 257: }
258:
1.65 deraadt 259: /*
260: * Signal handler for the key regeneration alarm. Note that this
261: * alarm only occurs in the daemon waiting for connections, and it does not
262: * do anything with the private key or random state before forking.
263: * Thus there should be no concurrency control/asynchronous execution
264: * problems.
265: */
1.105 markus 266: void
1.174 deraadt 267: generate_ephemeral_server_key(void)
1.134 markus 268: {
1.169 markus 269: u_int32_t rand = 0;
270: int i;
271:
1.134 markus 272: log("Generating %s%d bit RSA key.", sensitive_data.server_key ? "new " : "",
273: options.server_key_bits);
274: if (sensitive_data.server_key != NULL)
275: key_free(sensitive_data.server_key);
276: sensitive_data.server_key = key_generate(KEY_RSA1, options.server_key_bits);
1.169 markus 277: log("RSA key generation complete.");
278:
279: for (i = 0; i < SSH_SESSION_KEY_LENGTH; i++) {
280: if (i % 4 == 0)
281: rand = arc4random();
282: sensitive_data.ssh1_cookie[i] = rand & 0xff;
283: rand >>= 8;
284: }
1.134 markus 285: arc4random_stir();
286: }
1.147 deraadt 287:
1.134 markus 288: void
1.64 markus 289: key_regeneration_alarm(int sig)
1.1 deraadt 290: {
1.64 markus 291: int save_errno = errno;
1.151 markus 292: signal(SIGALRM, SIG_DFL);
1.64 markus 293: errno = save_errno;
1.151 markus 294: key_do_regen = 1;
1.98 markus 295: }
296:
1.96 markus 297: void
298: sshd_exchange_identification(int sock_in, int sock_out)
299: {
1.102 markus 300: int i, mismatch;
1.96 markus 301: int remote_major, remote_minor;
1.102 markus 302: int major, minor;
1.96 markus 303: char *s;
304: char buf[256]; /* Must not be larger than remote_version. */
305: char remote_version[256]; /* Must be at least as big as buf. */
306:
1.103 markus 307: if ((options.protocol & SSH_PROTO_1) &&
308: (options.protocol & SSH_PROTO_2)) {
1.102 markus 309: major = PROTOCOL_MAJOR_1;
310: minor = 99;
311: } else if (options.protocol & SSH_PROTO_2) {
312: major = PROTOCOL_MAJOR_2;
313: minor = PROTOCOL_MINOR_2;
314: } else {
315: major = PROTOCOL_MAJOR_1;
316: minor = PROTOCOL_MINOR_1;
317: }
318: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
1.96 markus 319: server_version_string = xstrdup(buf);
320:
321: if (client_version_string == NULL) {
322: /* Send our protocol version identification. */
323: if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
324: != strlen(server_version_string)) {
325: log("Could not write ident string to %s.", get_remote_ipaddr());
326: fatal_cleanup();
327: }
328:
1.167 markus 329: /* Read other side's version identification. */
330: memset(buf, 0, sizeof(buf));
1.96 markus 331: for (i = 0; i < sizeof(buf) - 1; i++) {
1.119 markus 332: if (atomicio(read, sock_in, &buf[i], 1) != 1) {
1.168 deraadt 333: log("Did not receive identification string from %s.",
334: get_remote_ipaddr());
1.96 markus 335: fatal_cleanup();
336: }
337: if (buf[i] == '\r') {
338: buf[i] = '\n';
339: buf[i + 1] = 0;
1.132 markus 340: /* Kludge for F-Secure Macintosh < 1.0.2 */
341: if (i == 12 &&
342: strncmp(buf, "SSH-1.5-W1.0", 12) == 0)
343: break;
1.96 markus 344: continue;
345: }
346: if (buf[i] == '\n') {
347: /* buf[i] == '\n' */
348: buf[i + 1] = 0;
349: break;
350: }
351: }
352: buf[sizeof(buf) - 1] = 0;
353: client_version_string = xstrdup(buf);
354: }
355:
356: /*
357: * Check that the versions match. In future this might accept
358: * several versions and set appropriate flags to handle them.
359: */
360: if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
361: &remote_major, &remote_minor, remote_version) != 3) {
1.105 markus 362: s = "Protocol mismatch.\n";
1.96 markus 363: (void) atomicio(write, sock_out, s, strlen(s));
364: close(sock_in);
365: close(sock_out);
366: log("Bad protocol version identification '%.100s' from %s",
367: client_version_string, get_remote_ipaddr());
368: fatal_cleanup();
369: }
370: debug("Client protocol version %d.%d; client software version %.100s",
371: remote_major, remote_minor, remote_version);
372:
1.98 markus 373: compat_datafellows(remote_version);
1.175 ! deraadt 374:
! 375: if (datafellows & SSH_BUG_SCANNER) {
! 376: log("scanned from %s with %s. Don't panic.",
! 377: get_remote_ipaddr(), client_version_string);
! 378: fatal_cleanup();
! 379: }
1.98 markus 380:
1.102 markus 381: mismatch = 0;
1.96 markus 382: switch(remote_major) {
383: case 1:
1.108 markus 384: if (remote_minor == 99) {
385: if (options.protocol & SSH_PROTO_2)
386: enable_compat20();
387: else
388: mismatch = 1;
389: break;
390: }
1.102 markus 391: if (!(options.protocol & SSH_PROTO_1)) {
392: mismatch = 1;
393: break;
394: }
1.96 markus 395: if (remote_minor < 3) {
1.121 provos 396: packet_disconnect("Your ssh version is too old and "
1.96 markus 397: "is no longer supported. Please install a newer version.");
398: } else if (remote_minor == 3) {
399: /* note that this disables agent-forwarding */
400: enable_compat13();
401: }
1.102 markus 402: break;
1.98 markus 403: case 2:
1.102 markus 404: if (options.protocol & SSH_PROTO_2) {
1.98 markus 405: enable_compat20();
406: break;
407: }
1.99 markus 408: /* FALLTHROUGH */
1.105 markus 409: default:
1.102 markus 410: mismatch = 1;
411: break;
412: }
413: chop(server_version_string);
414: chop(client_version_string);
415: debug("Local version string %.200s", server_version_string);
416:
417: if (mismatch) {
1.96 markus 418: s = "Protocol major versions differ.\n";
419: (void) atomicio(write, sock_out, s, strlen(s));
420: close(sock_in);
421: close(sock_out);
1.102 markus 422: log("Protocol major versions differ for %s: %.200s vs. %.200s",
423: get_remote_ipaddr(),
424: server_version_string, client_version_string);
1.96 markus 425: fatal_cleanup();
426: }
1.108 markus 427: if (compat20)
428: packet_set_ssh2_format();
429: }
430:
431:
1.134 markus 432: /* Destroy the host and server keys. They will no longer be needed. */
1.108 markus 433: void
434: destroy_sensitive_data(void)
435: {
1.134 markus 436: int i;
437:
438: if (sensitive_data.server_key) {
439: key_free(sensitive_data.server_key);
440: sensitive_data.server_key = NULL;
441: }
1.161 stevesk 442: for(i = 0; i < options.num_host_key_files; i++) {
1.134 markus 443: if (sensitive_data.host_keys[i]) {
444: key_free(sensitive_data.host_keys[i]);
445: sensitive_data.host_keys[i] = NULL;
446: }
447: }
448: sensitive_data.ssh1_host_key = NULL;
1.169 markus 449: memset(sensitive_data.ssh1_cookie, 0, SSH_SESSION_KEY_LENGTH);
1.134 markus 450: }
451: Key *
452: load_private_key_autodetect(const char *filename)
453: {
454: struct stat st;
455: int type;
456: Key *public, *private;
457:
458: if (stat(filename, &st) < 0) {
459: perror(filename);
460: return NULL;
461: }
462: /*
463: * try to load the public key. right now this only works for RSA1,
464: * since SSH2 keys are fully encrypted
465: */
466: type = KEY_RSA1;
467: public = key_new(type);
468: if (!load_public_key(filename, public, NULL)) {
469: /* ok, so we will assume this is 'some' key */
470: type = KEY_UNSPEC;
471: }
472: key_free(public);
473:
474: /* Ok, try key with empty passphrase */
475: private = key_new(type);
476: if (load_private_key(filename, "", private, NULL)) {
477: debug("load_private_key_autodetect: type %d %s",
478: private->type, key_type(private));
479: return private;
480: }
481: key_free(private);
482: return NULL;
483: }
484:
485: char *
486: list_hostkey_types(void)
487: {
488: static char buf[1024];
489: int i;
490: buf[0] = '\0';
491: for(i = 0; i < options.num_host_key_files; i++) {
492: Key *key = sensitive_data.host_keys[i];
493: if (key == NULL)
494: continue;
495: switch(key->type) {
496: case KEY_RSA:
497: case KEY_DSA:
498: strlcat(buf, key_ssh_name(key), sizeof buf);
499: strlcat(buf, ",", sizeof buf);
500: break;
501: }
502: }
503: i = strlen(buf);
504: if (i > 0 && buf[i-1] == ',')
505: buf[i-1] = '\0';
506: debug("list_hostkey_types: %s", buf);
507: return buf;
508: }
509:
510: Key *
511: get_hostkey_by_type(int type)
512: {
513: int i;
514: for(i = 0; i < options.num_host_key_files; i++) {
515: Key *key = sensitive_data.host_keys[i];
516: if (key != NULL && key->type == type)
517: return key;
518: }
519: return NULL;
1.96 markus 520: }
521:
1.124 markus 522: /*
523: * returns 1 if connection should be dropped, 0 otherwise.
524: * dropping starts at connection #max_startups_begin with a probability
525: * of (max_startups_rate/100). the probability increases linearly until
526: * all connections are dropped for startups > max_startups
527: */
528: int
529: drop_connection(int startups)
530: {
531: double p, r;
532:
533: if (startups < options.max_startups_begin)
534: return 0;
535: if (startups >= options.max_startups)
536: return 1;
537: if (options.max_startups_rate == 100)
538: return 1;
539:
540: p = 100 - options.max_startups_rate;
541: p *= startups - options.max_startups_begin;
542: p /= (double) (options.max_startups - options.max_startups_begin);
543: p += options.max_startups_rate;
544: p /= 100.0;
545: r = arc4random() / (double) UINT_MAX;
546:
547: debug("drop_connection: p %g, r %g", p, r);
548: return (r < p) ? 1 : 0;
549: }
550:
1.120 markus 551: int *startup_pipes = NULL; /* options.max_startup sized array of fd ints */
552: int startup_pipe; /* in child */
553:
1.65 deraadt 554: /*
555: * Main program for the daemon.
556: */
1.2 provos 557: int
558: main(int ac, char **av)
1.1 deraadt 559: {
1.64 markus 560: extern char *optarg;
561: extern int optind;
1.120 markus 562: int opt, sock_in = 0, sock_out = 0, newsock, j, i, fdsetsz, on = 1;
1.107 deraadt 563: pid_t pid;
1.75 markus 564: socklen_t fromlen;
565: fd_set *fdset;
566: struct sockaddr_storage from;
1.64 markus 567: const char *remote_ip;
568: int remote_port;
569: FILE *f;
570: struct linger linger;
1.75 markus 571: struct addrinfo *ai;
572: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
573: int listen_sock, maxfd;
1.120 markus 574: int startup_p[2];
575: int startups = 0;
1.151 markus 576: int ret, key_used = 0;
1.64 markus 577:
1.138 markus 578: /* Save argv. */
1.64 markus 579: saved_argv = av;
580:
581: /* Initialize configuration options to their default values. */
582: initialize_server_options(&options);
583:
584: /* Parse command-line arguments. */
1.149 markus 585: while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:u:dDiqQ46")) != -1) {
1.64 markus 586: switch (opt) {
1.75 markus 587: case '4':
588: IPv4or6 = AF_INET;
589: break;
590: case '6':
591: IPv4or6 = AF_INET6;
592: break;
1.64 markus 593: case 'f':
594: config_file_name = optarg;
595: break;
596: case 'd':
1.127 markus 597: if (0 == debug_flag) {
598: debug_flag = 1;
599: options.log_level = SYSLOG_LEVEL_DEBUG1;
600: } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
601: options.log_level++;
602: } else {
603: fprintf(stderr, "Too high debugging level.\n");
604: exit(1);
605: }
1.64 markus 606: break;
1.135 markus 607: case 'D':
608: no_daemon_flag = 1;
609: break;
1.64 markus 610: case 'i':
611: inetd_flag = 1;
612: break;
613: case 'Q':
1.158 markus 614: /* ignored */
1.64 markus 615: break;
616: case 'q':
617: options.log_level = SYSLOG_LEVEL_QUIET;
618: break;
619: case 'b':
620: options.server_key_bits = atoi(optarg);
621: break;
622: case 'p':
1.75 markus 623: options.ports_from_cmdline = 1;
1.127 markus 624: if (options.num_ports >= MAX_PORTS) {
625: fprintf(stderr, "too many ports.\n");
626: exit(1);
627: }
1.75 markus 628: options.ports[options.num_ports++] = atoi(optarg);
1.64 markus 629: break;
630: case 'g':
631: options.login_grace_time = atoi(optarg);
632: break;
633: case 'k':
634: options.key_regeneration_time = atoi(optarg);
635: break;
636: case 'h':
1.134 markus 637: if (options.num_host_key_files >= MAX_HOSTKEYS) {
638: fprintf(stderr, "too many host keys.\n");
639: exit(1);
640: }
641: options.host_key_files[options.num_host_key_files++] = optarg;
1.64 markus 642: break;
643: case 'V':
644: client_version_string = optarg;
645: /* only makes sense with inetd_flag, i.e. no listen() */
646: inetd_flag = 1;
647: break;
1.125 markus 648: case 'u':
649: utmp_len = atoi(optarg);
650: break;
1.64 markus 651: case '?':
652: default:
653: fprintf(stderr, "sshd version %s\n", SSH_VERSION);
1.138 markus 654: fprintf(stderr, "Usage: %s [options]\n", __progname);
1.64 markus 655: fprintf(stderr, "Options:\n");
1.154 markus 656: fprintf(stderr, " -f file Configuration file (default %s)\n", _PATH_SERVER_CONFIG_FILE);
1.127 markus 657: fprintf(stderr, " -d Debugging mode (multiple -d means more debugging)\n");
1.64 markus 658: fprintf(stderr, " -i Started from inetd\n");
1.144 markus 659: fprintf(stderr, " -D Do not fork into daemon mode\n");
1.64 markus 660: fprintf(stderr, " -q Quiet (no logging)\n");
661: fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
662: fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
1.145 markus 663: fprintf(stderr, " -g seconds Grace period for authentication (default: 600)\n");
1.64 markus 664: fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
665: fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
1.154 markus 666: _PATH_HOST_KEY_FILE);
1.125 markus 667: fprintf(stderr, " -u len Maximum hostname length for utmp recording\n");
1.75 markus 668: fprintf(stderr, " -4 Use IPv4 only\n");
669: fprintf(stderr, " -6 Use IPv6 only\n");
1.64 markus 670: exit(1);
671: }
672: }
673:
1.75 markus 674: /*
675: * Force logging to stderr until we have loaded the private host
676: * key (unless started from inetd)
677: */
1.138 markus 678: log_init(__progname,
1.152 markus 679: options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
1.75 markus 680: options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
1.158 markus 681: !inetd_flag);
1.75 markus 682:
1.64 markus 683: /* Read server configuration options from the configuration file. */
684: read_server_config(&options, config_file_name);
685:
686: /* Fill in default values for those options not explicitly set. */
687: fill_default_server_options(&options);
688:
689: /* Check that there are no remaining arguments. */
690: if (optind < ac) {
691: fprintf(stderr, "Extra argument %s.\n", av[optind]);
692: exit(1);
693: }
694:
695: debug("sshd version %.100s", SSH_VERSION);
696:
1.134 markus 697: /* load private host keys */
698: sensitive_data.host_keys = xmalloc(options.num_host_key_files*sizeof(Key*));
1.141 markus 699: for(i = 0; i < options.num_host_key_files; i++)
700: sensitive_data.host_keys[i] = NULL;
1.134 markus 701: sensitive_data.server_key = NULL;
702: sensitive_data.ssh1_host_key = NULL;
703: sensitive_data.have_ssh1_key = 0;
704: sensitive_data.have_ssh2_key = 0;
705:
706: for(i = 0; i < options.num_host_key_files; i++) {
707: Key *key = load_private_key_autodetect(options.host_key_files[i]);
708: if (key == NULL) {
709: error("Could not load host key: %.200s: %.100s",
710: options.host_key_files[i], strerror(errno));
711: continue;
712: }
713: switch(key->type){
714: case KEY_RSA1:
715: sensitive_data.ssh1_host_key = key;
716: sensitive_data.have_ssh1_key = 1;
717: break;
718: case KEY_RSA:
719: case KEY_DSA:
720: sensitive_data.have_ssh2_key = 1;
721: break;
722: }
723: sensitive_data.host_keys[i] = key;
724: }
725: if ((options.protocol & SSH_PROTO_1) && !sensitive_data.have_ssh1_key) {
726: log("Disabling protocol version 1. Could not load host key");
1.108 markus 727: options.protocol &= ~SSH_PROTO_1;
728: }
1.134 markus 729: if ((options.protocol & SSH_PROTO_2) && !sensitive_data.have_ssh2_key) {
730: log("Disabling protocol version 2. Could not load host key");
731: options.protocol &= ~SSH_PROTO_2;
1.108 markus 732: }
1.162 stevesk 733: if (!(options.protocol & (SSH_PROTO_1|SSH_PROTO_2))) {
1.172 millert 734: log("sshd: no hostkeys available -- exiting.");
1.64 markus 735: exit(1);
736: }
737:
1.108 markus 738: /* Check certain values for sanity. */
739: if (options.protocol & SSH_PROTO_1) {
740: if (options.server_key_bits < 512 ||
741: options.server_key_bits > 32768) {
742: fprintf(stderr, "Bad server key size.\n");
743: exit(1);
744: }
745: /*
746: * Check that server and host key lengths differ sufficiently. This
747: * is necessary to make double encryption work with rsaref. Oh, I
748: * hate software patents. I dont know if this can go? Niels
749: */
750: if (options.server_key_bits >
1.134 markus 751: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) - SSH_KEY_BITS_RESERVED &&
1.108 markus 752: options.server_key_bits <
1.134 markus 753: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1.108 markus 754: options.server_key_bits =
1.134 markus 755: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED;
1.108 markus 756: debug("Forcing server key to %d bits to make it differ from host key.",
757: options.server_key_bits);
758: }
759: }
760:
761: /* Initialize the log (it is reinitialized below in case we forked). */
1.64 markus 762: if (debug_flag && !inetd_flag)
763: log_stderr = 1;
1.138 markus 764: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.64 markus 765:
1.108 markus 766: /*
767: * If not in debugging mode, and not started from inetd, disconnect
768: * from the controlling terminal, and fork. The original process
769: * exits.
770: */
1.135 markus 771: if (!(debug_flag || inetd_flag || no_daemon_flag)) {
1.1 deraadt 772: #ifdef TIOCNOTTY
1.64 markus 773: int fd;
1.1 deraadt 774: #endif /* TIOCNOTTY */
1.64 markus 775: if (daemon(0, 0) < 0)
776: fatal("daemon() failed: %.200s", strerror(errno));
777:
778: /* Disconnect from the controlling tty. */
1.1 deraadt 779: #ifdef TIOCNOTTY
1.165 itojun 780: fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
1.64 markus 781: if (fd >= 0) {
782: (void) ioctl(fd, TIOCNOTTY, NULL);
783: close(fd);
784: }
785: #endif /* TIOCNOTTY */
786: }
787: /* Reinitialize the log (because of the fork above). */
1.138 markus 788: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.64 markus 789:
790: /* Initialize the random number generator. */
791: arc4random_stir();
792:
793: /* Chdir to the root directory so that the current disk can be
794: unmounted if desired. */
795: chdir("/");
796:
797: /* Start listening for a socket, unless started from inetd. */
798: if (inetd_flag) {
799: int s1, s2;
800: s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
801: s2 = dup(s1);
802: sock_in = dup(0);
803: sock_out = dup(1);
1.123 djm 804: startup_pipe = -1;
1.108 markus 805: /*
806: * We intentionally do not close the descriptors 0, 1, and 2
807: * as our code for setting the descriptors won\'t work if
808: * ttyfd happens to be one of those.
809: */
1.64 markus 810: debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
1.134 markus 811: if (options.protocol & SSH_PROTO_1)
1.174 deraadt 812: generate_ephemeral_server_key();
1.64 markus 813: } else {
1.75 markus 814: for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
815: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
816: continue;
817: if (num_listen_socks >= MAX_LISTEN_SOCKS)
818: fatal("Too many listen sockets. "
819: "Enlarge MAX_LISTEN_SOCKS");
820: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
821: ntop, sizeof(ntop), strport, sizeof(strport),
822: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
823: error("getnameinfo failed");
824: continue;
825: }
826: /* Create socket for listening. */
827: listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
828: if (listen_sock < 0) {
829: /* kernel may not support ipv6 */
830: verbose("socket: %.100s", strerror(errno));
831: continue;
832: }
833: if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
834: error("listen_sock O_NONBLOCK: %s", strerror(errno));
835: close(listen_sock);
836: continue;
837: }
838: /*
839: * Set socket options. We try to make the port
840: * reusable and have it close as fast as possible
841: * without waiting in unnecessary wait states on
842: * close.
843: */
844: setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
845: (void *) &on, sizeof(on));
846: linger.l_onoff = 1;
847: linger.l_linger = 5;
848: setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
849: (void *) &linger, sizeof(linger));
850:
851: debug("Bind to port %s on %s.", strport, ntop);
852:
853: /* Bind the socket to the desired port. */
854: if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
855: error("Bind to port %s on %s failed: %.200s.",
856: strport, ntop, strerror(errno));
857: close(listen_sock);
858: continue;
859: }
860: listen_socks[num_listen_socks] = listen_sock;
861: num_listen_socks++;
862:
863: /* Start listening on the port. */
864: log("Server listening on %s port %s.", ntop, strport);
865: if (listen(listen_sock, 5) < 0)
866: fatal("listen: %.100s", strerror(errno));
867:
1.64 markus 868: }
1.75 markus 869: freeaddrinfo(options.listen_addrs);
870:
871: if (!num_listen_socks)
872: fatal("Cannot bind any address.");
873:
1.64 markus 874: if (!debug_flag) {
1.66 markus 875: /*
1.136 todd 876: * Record our pid in /var/run/sshd.pid to make it
877: * easier to kill the correct sshd. We don't want to
878: * do this before the bind above because the bind will
1.66 markus 879: * fail if there already is a daemon, and this will
880: * overwrite any old pid in the file.
881: */
1.112 markus 882: f = fopen(options.pid_file, "w");
1.64 markus 883: if (f) {
1.140 markus 884: fprintf(f, "%u\n", (u_int) getpid());
1.64 markus 885: fclose(f);
886: }
887: }
1.151 markus 888: if (options.protocol & SSH_PROTO_1)
1.174 deraadt 889: generate_ephemeral_server_key();
1.64 markus 890:
891: /* Arrange to restart on SIGHUP. The handler needs listen_sock. */
892: signal(SIGHUP, sighup_handler);
1.120 markus 893:
1.64 markus 894: signal(SIGTERM, sigterm_handler);
895: signal(SIGQUIT, sigterm_handler);
896:
897: /* Arrange SIGCHLD to be caught. */
898: signal(SIGCHLD, main_sigchld_handler);
899:
1.75 markus 900: /* setup fd set for listen */
1.120 markus 901: fdset = NULL;
1.75 markus 902: maxfd = 0;
903: for (i = 0; i < num_listen_socks; i++)
904: if (listen_socks[i] > maxfd)
905: maxfd = listen_socks[i];
1.120 markus 906: /* pipes connected to unauthenticated childs */
907: startup_pipes = xmalloc(options.max_startups * sizeof(int));
908: for (i = 0; i < options.max_startups; i++)
909: startup_pipes[i] = -1;
1.75 markus 910:
1.66 markus 911: /*
912: * Stay listening for connections until the system crashes or
913: * the daemon is killed with a signal.
914: */
1.64 markus 915: for (;;) {
916: if (received_sighup)
917: sighup_restart();
1.120 markus 918: if (fdset != NULL)
919: xfree(fdset);
1.148 markus 920: fdsetsz = howmany(maxfd+1, NFDBITS) * sizeof(fd_mask);
1.120 markus 921: fdset = (fd_set *)xmalloc(fdsetsz);
1.75 markus 922: memset(fdset, 0, fdsetsz);
1.120 markus 923:
1.75 markus 924: for (i = 0; i < num_listen_socks; i++)
925: FD_SET(listen_socks[i], fdset);
1.120 markus 926: for (i = 0; i < options.max_startups; i++)
927: if (startup_pipes[i] != -1)
928: FD_SET(startup_pipes[i], fdset);
929:
930: /* Wait in select until there is a connection. */
1.151 markus 931: ret = select(maxfd+1, fdset, NULL, NULL, NULL);
932: if (ret < 0 && errno != EINTR)
933: error("select: %.100s", strerror(errno));
934: if (key_used && key_do_regen) {
1.174 deraadt 935: generate_ephemeral_server_key();
1.151 markus 936: key_used = 0;
937: key_do_regen = 0;
938: }
939: if (ret < 0)
1.75 markus 940: continue;
1.151 markus 941:
1.120 markus 942: for (i = 0; i < options.max_startups; i++)
943: if (startup_pipes[i] != -1 &&
944: FD_ISSET(startup_pipes[i], fdset)) {
945: /*
946: * the read end of the pipe is ready
947: * if the child has closed the pipe
1.143 markus 948: * after successful authentication
1.120 markus 949: * or if the child has died
950: */
951: close(startup_pipes[i]);
952: startup_pipes[i] = -1;
953: startups--;
954: }
1.75 markus 955: for (i = 0; i < num_listen_socks; i++) {
956: if (!FD_ISSET(listen_socks[i], fdset))
1.70 provos 957: continue;
1.120 markus 958: fromlen = sizeof(from);
959: newsock = accept(listen_socks[i], (struct sockaddr *)&from,
960: &fromlen);
961: if (newsock < 0) {
962: if (errno != EINTR && errno != EWOULDBLOCK)
963: error("accept: %.100s", strerror(errno));
964: continue;
965: }
966: if (fcntl(newsock, F_SETFL, 0) < 0) {
967: error("newsock del O_NONBLOCK: %s", strerror(errno));
968: continue;
969: }
1.124 markus 970: if (drop_connection(startups) == 1) {
971: debug("drop connection #%d", startups);
1.120 markus 972: close(newsock);
973: continue;
974: }
975: if (pipe(startup_p) == -1) {
976: close(newsock);
977: continue;
978: }
979:
980: for (j = 0; j < options.max_startups; j++)
981: if (startup_pipes[j] == -1) {
982: startup_pipes[j] = startup_p[0];
983: if (maxfd < startup_p[0])
984: maxfd = startup_p[0];
985: startups++;
986: break;
987: }
1.161 stevesk 988:
1.66 markus 989: /*
1.120 markus 990: * Got connection. Fork a child to handle it, unless
991: * we are in debugging mode.
1.66 markus 992: */
1.120 markus 993: if (debug_flag) {
1.66 markus 994: /*
1.120 markus 995: * In debugging mode. Close the listening
996: * socket, and start processing the
997: * connection without forking.
1.66 markus 998: */
1.120 markus 999: debug("Server will not fork when running in debugging mode.");
1.75 markus 1000: close_listen_socks();
1.64 markus 1001: sock_in = newsock;
1002: sock_out = newsock;
1.122 deraadt 1003: startup_pipe = -1;
1.120 markus 1004: pid = getpid();
1.64 markus 1005: break;
1.120 markus 1006: } else {
1007: /*
1008: * Normal production daemon. Fork, and have
1009: * the child process the connection. The
1010: * parent continues listening.
1011: */
1012: if ((pid = fork()) == 0) {
1013: /*
1014: * Child. Close the listening and max_startup
1015: * sockets. Start using the accepted socket.
1016: * Reinitialize logging (since our pid has
1017: * changed). We break out of the loop to handle
1018: * the connection.
1019: */
1020: startup_pipe = startup_p[1];
1021: for (j = 0; j < options.max_startups; j++)
1022: if (startup_pipes[j] != -1)
1023: close(startup_pipes[j]);
1024: close_listen_socks();
1025: sock_in = newsock;
1026: sock_out = newsock;
1.138 markus 1027: log_init(__progname, options.log_level, options.log_facility, log_stderr);
1.120 markus 1028: break;
1029: }
1.64 markus 1030: }
1031:
1.120 markus 1032: /* Parent. Stay in the loop. */
1033: if (pid < 0)
1034: error("fork: %.100s", strerror(errno));
1035: else
1036: debug("Forked child %d.", pid);
1037:
1038: close(startup_p[1]);
1.1 deraadt 1039:
1.120 markus 1040: /* Mark that the key has been used (it was "given" to the child). */
1.151 markus 1041: if ((options.protocol & SSH_PROTO_1) &&
1042: key_used == 0) {
1043: /* Schedule server key regeneration alarm. */
1044: signal(SIGALRM, key_regeneration_alarm);
1045: alarm(options.key_regeneration_time);
1046: key_used = 1;
1047: }
1.1 deraadt 1048:
1.120 markus 1049: arc4random_stir();
1.1 deraadt 1050:
1.120 markus 1051: /* Close the new socket (the child is now taking care of it). */
1052: close(newsock);
1053: }
1.75 markus 1054: /* child process check (or debug mode) */
1055: if (num_listen_socks < 0)
1056: break;
1.64 markus 1057: }
1.1 deraadt 1058: }
1059:
1.64 markus 1060: /* This is the child processing a new connection. */
1061:
1.66 markus 1062: /*
1063: * Disable the key regeneration alarm. We will not regenerate the
1064: * key since we are no longer in a position to give it to anyone. We
1065: * will not restart on SIGHUP since it no longer makes sense.
1066: */
1.64 markus 1067: alarm(0);
1068: signal(SIGALRM, SIG_DFL);
1069: signal(SIGHUP, SIG_DFL);
1070: signal(SIGTERM, SIG_DFL);
1071: signal(SIGQUIT, SIG_DFL);
1072: signal(SIGCHLD, SIG_DFL);
1073:
1.66 markus 1074: /*
1075: * Set socket options for the connection. We want the socket to
1076: * close as fast as possible without waiting for anything. If the
1077: * connection is not a socket, these will do nothing.
1078: */
1079: /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.64 markus 1080: linger.l_onoff = 1;
1081: linger.l_linger = 5;
1082: setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
1.150 markus 1083:
1084: /* Set keepalives if requested. */
1085: if (options.keepalives &&
1086: setsockopt(sock_in, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1087: sizeof(on)) < 0)
1088: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.64 markus 1089:
1.66 markus 1090: /*
1091: * Register our connection. This turns encryption off because we do
1092: * not have a key.
1093: */
1.64 markus 1094: packet_set_connection(sock_in, sock_out);
1.1 deraadt 1095:
1.64 markus 1096: remote_port = get_remote_port();
1097: remote_ip = get_remote_ipaddr();
1.52 markus 1098:
1.64 markus 1099: /* Check whether logins are denied from this host. */
1.37 dugsong 1100: #ifdef LIBWRAP
1.75 markus 1101: /* XXX LIBWRAP noes not know about IPv6 */
1.64 markus 1102: {
1103: struct request_info req;
1.37 dugsong 1104:
1.138 markus 1105: request_init(&req, RQ_DAEMON, __progname, RQ_FILE, sock_in, NULL);
1.64 markus 1106: fromhost(&req);
1.37 dugsong 1107:
1.64 markus 1108: if (!hosts_access(&req)) {
1109: close(sock_in);
1110: close(sock_out);
1111: refuse(&req);
1112: }
1.75 markus 1113: /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */
1.64 markus 1114: }
1.75 markus 1115: #endif /* LIBWRAP */
1.64 markus 1116: /* Log the connection. */
1117: verbose("Connection from %.500s port %d", remote_ip, remote_port);
1.1 deraadt 1118:
1.66 markus 1119: /*
1120: * We don\'t want to listen forever unless the other side
1121: * successfully authenticates itself. So we set up an alarm which is
1122: * cleared after successful authentication. A limit of zero
1123: * indicates no limit. Note that we don\'t set the alarm in debugging
1124: * mode; it is just annoying to have the server exit just when you
1125: * are about to discover the bug.
1126: */
1.64 markus 1127: signal(SIGALRM, grace_alarm_handler);
1128: if (!debug_flag)
1129: alarm(options.login_grace_time);
1130:
1.96 markus 1131: sshd_exchange_identification(sock_in, sock_out);
1.66 markus 1132: /*
1.137 markus 1133: * Check that the connection comes from a privileged port.
1134: * Rhosts-Authentication only makes sense from priviledged
1.66 markus 1135: * programs. Of course, if the intruder has root access on his local
1136: * machine, he can connect from any port. So do not use these
1137: * authentication methods from machines that you do not trust.
1138: */
1.64 markus 1139: if (remote_port >= IPPORT_RESERVED ||
1140: remote_port < IPPORT_RESERVED / 2) {
1.137 markus 1141: debug("Rhosts Authentication disabled, "
1.133 markus 1142: "originating port not trusted.");
1.64 markus 1143: options.rhosts_authentication = 0;
1144: }
1.76 markus 1145: #ifdef KRB4
1146: if (!packet_connection_is_ipv4() &&
1147: options.kerberos_authentication) {
1148: debug("Kerberos Authentication disabled, only available for IPv4.");
1149: options.kerberos_authentication = 0;
1150: }
1151: #endif /* KRB4 */
1.164 markus 1152: #ifdef AFS
1153: /* If machine has AFS, set process authentication group. */
1154: if (k_hasafs()) {
1155: k_setpag();
1156: k_unlog();
1157: }
1158: #endif /* AFS */
1.76 markus 1159:
1.64 markus 1160: packet_set_nonblocking();
1.1 deraadt 1161:
1.77 markus 1162: /* perform the key exchange */
1163: /* authenticate user and start session */
1.98 markus 1164: if (compat20) {
1165: do_ssh2_kex();
1166: do_authentication2();
1167: } else {
1168: do_ssh1_kex();
1169: do_authentication();
1170: }
1.1 deraadt 1171:
1172: #ifdef KRB4
1.64 markus 1173: /* Cleanup user's ticket cache file. */
1174: if (options.kerberos_ticket_cleanup)
1175: (void) dest_tkt();
1.1 deraadt 1176: #endif /* KRB4 */
1177:
1.64 markus 1178: /* The connection has been terminated. */
1179: verbose("Closing connection to %.100s", remote_ip);
1180: packet_close();
1181: exit(0);
1.1 deraadt 1182: }
1183:
1.65 deraadt 1184: /*
1.77 markus 1185: * SSH1 key exchange
1.65 deraadt 1186: */
1.52 markus 1187: void
1.142 markus 1188: do_ssh1_kex(void)
1.1 deraadt 1189: {
1.64 markus 1190: int i, len;
1.77 markus 1191: int plen, slen;
1.159 markus 1192: int rsafail = 0;
1.64 markus 1193: BIGNUM *session_key_int;
1.140 markus 1194: u_char session_key[SSH_SESSION_KEY_LENGTH];
1195: u_char cookie[8];
1196: u_int cipher_type, auth_mask, protocol_flags;
1.64 markus 1197: u_int32_t rand = 0;
1198:
1.66 markus 1199: /*
1200: * Generate check bytes that the client must send back in the user
1201: * packet in order for it to be accepted; this is used to defy ip
1202: * spoofing attacks. Note that this only works against somebody
1203: * doing IP spoofing from a remote machine; any machine on the local
1204: * network can still see outgoing packets and catch the random
1205: * cookie. This only affects rhosts authentication, and this is one
1206: * of the reasons why it is inherently insecure.
1207: */
1.64 markus 1208: for (i = 0; i < 8; i++) {
1209: if (i % 4 == 0)
1210: rand = arc4random();
1.77 markus 1211: cookie[i] = rand & 0xff;
1.64 markus 1212: rand >>= 8;
1213: }
1214:
1.66 markus 1215: /*
1216: * Send our public key. We include in the packet 64 bits of random
1217: * data that must be matched in the reply in order to prevent IP
1218: * spoofing.
1219: */
1.64 markus 1220: packet_start(SSH_SMSG_PUBLIC_KEY);
1221: for (i = 0; i < 8; i++)
1.77 markus 1222: packet_put_char(cookie[i]);
1.64 markus 1223:
1224: /* Store our public server RSA key. */
1.134 markus 1225: packet_put_int(BN_num_bits(sensitive_data.server_key->rsa->n));
1226: packet_put_bignum(sensitive_data.server_key->rsa->e);
1227: packet_put_bignum(sensitive_data.server_key->rsa->n);
1.64 markus 1228:
1229: /* Store our public host RSA key. */
1.134 markus 1230: packet_put_int(BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1231: packet_put_bignum(sensitive_data.ssh1_host_key->rsa->e);
1232: packet_put_bignum(sensitive_data.ssh1_host_key->rsa->n);
1.64 markus 1233:
1234: /* Put protocol flags. */
1235: packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1236:
1237: /* Declare which ciphers we support. */
1.131 markus 1238: packet_put_int(cipher_mask_ssh1(0));
1.64 markus 1239:
1240: /* Declare supported authentication types. */
1241: auth_mask = 0;
1242: if (options.rhosts_authentication)
1243: auth_mask |= 1 << SSH_AUTH_RHOSTS;
1244: if (options.rhosts_rsa_authentication)
1245: auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1246: if (options.rsa_authentication)
1247: auth_mask |= 1 << SSH_AUTH_RSA;
1.1 deraadt 1248: #ifdef KRB4
1.64 markus 1249: if (options.kerberos_authentication)
1250: auth_mask |= 1 << SSH_AUTH_KERBEROS;
1.1 deraadt 1251: #endif
1.5 dugsong 1252: #ifdef AFS
1.64 markus 1253: if (options.kerberos_tgt_passing)
1254: auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
1255: if (options.afs_token_passing)
1256: auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
1.1 deraadt 1257: #endif
1.157 markus 1258: if (options.challenge_reponse_authentication == 1)
1.64 markus 1259: auth_mask |= 1 << SSH_AUTH_TIS;
1260: if (options.password_authentication)
1261: auth_mask |= 1 << SSH_AUTH_PASSWORD;
1262: packet_put_int(auth_mask);
1263:
1264: /* Send the packet and wait for it to be sent. */
1265: packet_send();
1266: packet_write_wait();
1267:
1.134 markus 1268: debug("Sent %d bit server key and %d bit host key.",
1269: BN_num_bits(sensitive_data.server_key->rsa->n),
1270: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n));
1.64 markus 1271:
1272: /* Read clients reply (cipher type and session key). */
1273: packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
1274:
1.69 markus 1275: /* Get cipher type and check whether we accept this. */
1.64 markus 1276: cipher_type = packet_get_char();
1.69 markus 1277:
1.131 markus 1278: if (!(cipher_mask_ssh1(0) & (1 << cipher_type)))
1.69 markus 1279: packet_disconnect("Warning: client selects unsupported cipher.");
1.64 markus 1280:
1281: /* Get check bytes from the packet. These must match those we
1282: sent earlier with the public key packet. */
1283: for (i = 0; i < 8; i++)
1.77 markus 1284: if (cookie[i] != packet_get_char())
1.64 markus 1285: packet_disconnect("IP Spoofing check bytes do not match.");
1286:
1287: debug("Encryption type: %.200s", cipher_name(cipher_type));
1288:
1289: /* Get the encrypted integer. */
1290: session_key_int = BN_new();
1291: packet_get_bignum(session_key_int, &slen);
1292:
1293: protocol_flags = packet_get_int();
1294: packet_set_protocol_flags(protocol_flags);
1295:
1296: packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
1297:
1.66 markus 1298: /*
1299: * Decrypt it using our private server key and private host key (key
1300: * with larger modulus first).
1301: */
1.134 markus 1302: if (BN_cmp(sensitive_data.server_key->rsa->n, sensitive_data.ssh1_host_key->rsa->n) > 0) {
1.159 markus 1303: /* Server key has bigger modulus. */
1.134 markus 1304: if (BN_num_bits(sensitive_data.server_key->rsa->n) <
1305: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1306: fatal("do_connection: %s: server_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1307: get_remote_ipaddr(),
1308: BN_num_bits(sensitive_data.server_key->rsa->n),
1309: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1310: SSH_KEY_BITS_RESERVED);
1.64 markus 1311: }
1.159 markus 1312: if (rsa_private_decrypt(session_key_int, session_key_int,
1313: sensitive_data.server_key->rsa) <= 0)
1314: rsafail++;
1315: if (rsa_private_decrypt(session_key_int, session_key_int,
1316: sensitive_data.ssh1_host_key->rsa) <= 0)
1317: rsafail++;
1.64 markus 1318: } else {
1319: /* Host key has bigger modulus (or they are equal). */
1.134 markus 1320: if (BN_num_bits(sensitive_data.ssh1_host_key->rsa->n) <
1321: BN_num_bits(sensitive_data.server_key->rsa->n) + SSH_KEY_BITS_RESERVED) {
1322: fatal("do_connection: %s: host_key %d < server_key %d + SSH_KEY_BITS_RESERVED %d",
1323: get_remote_ipaddr(),
1324: BN_num_bits(sensitive_data.ssh1_host_key->rsa->n),
1325: BN_num_bits(sensitive_data.server_key->rsa->n),
1326: SSH_KEY_BITS_RESERVED);
1.64 markus 1327: }
1.159 markus 1328: if (rsa_private_decrypt(session_key_int, session_key_int,
1329: sensitive_data.ssh1_host_key->rsa) < 0)
1330: rsafail++;
1331: if (rsa_private_decrypt(session_key_int, session_key_int,
1332: sensitive_data.server_key->rsa) < 0)
1333: rsafail++;
1.64 markus 1334: }
1.66 markus 1335: /*
1336: * Extract session key from the decrypted integer. The key is in the
1337: * least significant 256 bits of the integer; the first byte of the
1338: * key is in the highest bits.
1339: */
1.159 markus 1340: if (!rsafail) {
1341: BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1342: len = BN_num_bytes(session_key_int);
1343: if (len < 0 || len > sizeof(session_key)) {
1344: error("do_connection: bad session key len from %s: "
1.165 itojun 1345: "session_key_int %d > sizeof(session_key) %lu",
1346: get_remote_ipaddr(), len, (u_long)sizeof(session_key));
1.159 markus 1347: rsafail++;
1348: } else {
1349: memset(session_key, 0, sizeof(session_key));
1350: BN_bn2bin(session_key_int,
1351: session_key + sizeof(session_key) - len);
1.169 markus 1352:
1353: compute_session_id(session_id, cookie,
1354: sensitive_data.ssh1_host_key->rsa->n,
1355: sensitive_data.server_key->rsa->n);
1356: /*
1357: * Xor the first 16 bytes of the session key with the
1358: * session id.
1359: */
1360: for (i = 0; i < 16; i++)
1361: session_key[i] ^= session_id[i];
1.159 markus 1362: }
1363: }
1364: if (rsafail) {
1.169 markus 1365: int bytes = BN_num_bytes(session_key_int);
1366: char *buf = xmalloc(bytes);
1367: MD5_CTX md;
1368:
1.159 markus 1369: log("do_connection: generating a fake encryption key");
1.169 markus 1370: BN_bn2bin(session_key_int, buf);
1371: MD5_Init(&md);
1372: MD5_Update(&md, buf, bytes);
1373: MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1374: MD5_Final(session_key, &md);
1375: MD5_Init(&md);
1376: MD5_Update(&md, session_key, 16);
1377: MD5_Update(&md, buf, bytes);
1378: MD5_Update(&md, sensitive_data.ssh1_cookie, SSH_SESSION_KEY_LENGTH);
1379: MD5_Final(session_key + 16, &md);
1380: memset(buf, 0, bytes);
1381: xfree(buf);
1.170 markus 1382: for (i = 0; i < 16; i++)
1383: session_id[i] = session_key[i] ^ session_key[i + 16];
1.159 markus 1384: }
1.169 markus 1385: /* Destroy the private and public keys. They will no longer be needed. */
1386: destroy_sensitive_data();
1387:
1.77 markus 1388: /* Destroy the decrypted integer. It is no longer needed. */
1389: BN_clear_free(session_key_int);
1.64 markus 1390:
1391: /* Set the session key. From this on all communications will be encrypted. */
1392: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1393:
1394: /* Destroy our copy of the session key. It is no longer needed. */
1395: memset(session_key, 0, sizeof(session_key));
1396:
1397: debug("Received session key; encryption turned on.");
1398:
1399: /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1400: packet_start(SSH_SMSG_SUCCESS);
1401: packet_send();
1402: packet_write_wait();
1.98 markus 1403: }
1404:
1405: /*
1406: * SSH2 key exchange: diffie-hellman-group1-sha1
1407: */
1408: void
1.142 markus 1409: do_ssh2_kex(void)
1.98 markus 1410: {
1411: Buffer *server_kexinit;
1412: Buffer *client_kexinit;
1.129 provos 1413: int payload_len;
1.98 markus 1414: int i;
1415: Kex *kex;
1416: char *cprop[PROPOSAL_MAX];
1417:
1418: /* KEXINIT */
1.102 markus 1419:
1420: if (options.ciphers != NULL) {
1.105 markus 1421: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1.102 markus 1422: myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1.166 markus 1423: }
1424: if (options.macs != NULL) {
1425: myproposal[PROPOSAL_MAC_ALGS_CTOS] =
1426: myproposal[PROPOSAL_MAC_ALGS_STOC] = options.macs;
1.102 markus 1427: }
1.134 markus 1428: myproposal[PROPOSAL_SERVER_HOST_KEY_ALGS] = list_hostkey_types();
1429:
1.118 markus 1430: server_kexinit = kex_init(myproposal);
1.98 markus 1431: client_kexinit = xmalloc(sizeof(*client_kexinit));
1432: buffer_init(client_kexinit);
1433:
1.118 markus 1434: /* algorithm negotiation */
1435: kex_exchange_kexinit(server_kexinit, client_kexinit, cprop);
1436: kex = kex_choose_conf(cprop, myproposal, 1);
1437: for (i = 0; i < PROPOSAL_MAX; i++)
1438: xfree(cprop[i]);
1.98 markus 1439:
1.129 provos 1440: switch (kex->kex_type) {
1441: case DH_GRP1_SHA1:
1442: ssh_dh1_server(kex, client_kexinit, server_kexinit);
1443: break;
1444: case DH_GEX_SHA1:
1445: ssh_dhgex_server(kex, client_kexinit, server_kexinit);
1446: break;
1447: default:
1448: fatal("Unsupported key exchange %d", kex->kex_type);
1449: }
1450:
1451: debug("send SSH2_MSG_NEWKEYS.");
1452: packet_start(SSH2_MSG_NEWKEYS);
1453: packet_send();
1454: packet_write_wait();
1455: debug("done: send SSH2_MSG_NEWKEYS.");
1456:
1457: debug("Wait SSH2_MSG_NEWKEYS.");
1458: packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
1459: debug("GOT SSH2_MSG_NEWKEYS.");
1460:
1461: #ifdef DEBUG_KEXDH
1462: /* send 1st encrypted/maced/compressed message */
1463: packet_start(SSH2_MSG_IGNORE);
1464: packet_put_cstring("markus");
1465: packet_send();
1466: packet_write_wait();
1467: #endif
1468:
1469: debug("done: KEX2.");
1470: }
1471:
1472: /*
1473: * SSH2 key exchange
1474: */
1475:
1476: /* diffie-hellman-group1-sha1 */
1477:
1478: void
1479: ssh_dh1_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1480: {
1.130 markus 1481: #ifdef DEBUG_KEXDH
1482: int i;
1483: #endif
1.129 provos 1484: int payload_len, dlen;
1485: int slen;
1.140 markus 1486: u_char *signature = NULL;
1487: u_char *server_host_key_blob = NULL;
1488: u_int sbloblen;
1489: u_int klen, kout;
1490: u_char *kbuf;
1491: u_char *hash;
1.129 provos 1492: BIGNUM *shared_secret = 0;
1493: DH *dh;
1494: BIGNUM *dh_client_pub = 0;
1.134 markus 1495: Key *hostkey;
1496:
1497: hostkey = get_hostkey_by_type(kex->hostkey_type);
1498: if (hostkey == NULL)
1499: fatal("Unsupported hostkey type %d", kex->hostkey_type);
1.129 provos 1500:
1.98 markus 1501: /* KEXDH */
1.139 provos 1502: /* generate DH key */
1503: dh = dh_new_group1(); /* XXX depends on 'kex' */
1.173 markus 1504: dh_gen_key(dh, kex->we_need * 8);
1.139 provos 1505:
1.98 markus 1506: debug("Wait SSH2_MSG_KEXDH_INIT.");
1507: packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT);
1508:
1509: /* key, cert */
1510: dh_client_pub = BN_new();
1511: if (dh_client_pub == NULL)
1512: fatal("dh_client_pub == NULL");
1513: packet_get_bignum2(dh_client_pub, &dlen);
1514:
1515: #ifdef DEBUG_KEXDH
1516: fprintf(stderr, "\ndh_client_pub= ");
1.128 markus 1517: BN_print_fp(stderr, dh_client_pub);
1.98 markus 1518: fprintf(stderr, "\n");
1519: debug("bits %d", BN_num_bits(dh_client_pub));
1520: #endif
1521:
1522: #ifdef DEBUG_KEXDH
1523: fprintf(stderr, "\np= ");
1.128 markus 1524: BN_print_fp(stderr, dh->p);
1.98 markus 1525: fprintf(stderr, "\ng= ");
1.128 markus 1526: bn_print(dh->g);
1.98 markus 1527: fprintf(stderr, "\npub= ");
1.128 markus 1528: BN_print_fp(stderr, dh->pub_key);
1.98 markus 1529: fprintf(stderr, "\n");
1.161 stevesk 1530: DHparams_print_fp(stderr, dh);
1.98 markus 1531: #endif
1.101 markus 1532: if (!dh_pub_is_valid(dh, dh_client_pub))
1533: packet_disconnect("bad client public DH value");
1.98 markus 1534:
1535: klen = DH_size(dh);
1536: kbuf = xmalloc(klen);
1537: kout = DH_compute_key(kbuf, dh_client_pub, dh);
1538:
1539: #ifdef DEBUG_KEXDH
1540: debug("shared secret: len %d/%d", klen, kout);
1541: fprintf(stderr, "shared secret == ");
1542: for (i = 0; i< kout; i++)
1543: fprintf(stderr, "%02x", (kbuf[i])&0xff);
1544: fprintf(stderr, "\n");
1545: #endif
1546: shared_secret = BN_new();
1547:
1548: BN_bin2bn(kbuf, kout, shared_secret);
1549: memset(kbuf, 0, klen);
1550: xfree(kbuf);
1551:
1.111 markus 1552: /* XXX precompute? */
1.134 markus 1553: key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
1.98 markus 1554:
1555: /* calc H */ /* XXX depends on 'kex' */
1556: hash = kex_hash(
1557: client_version_string,
1558: server_version_string,
1559: buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1560: buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1561: (char *)server_host_key_blob, sbloblen,
1562: dh_client_pub,
1563: dh->pub_key,
1564: shared_secret
1565: );
1566: buffer_free(client_kexinit);
1567: buffer_free(server_kexinit);
1568: xfree(client_kexinit);
1569: xfree(server_kexinit);
1.156 stevesk 1570: BN_free(dh_client_pub);
1.98 markus 1571: #ifdef DEBUG_KEXDH
1.105 markus 1572: fprintf(stderr, "hash == ");
1573: for (i = 0; i< 20; i++)
1574: fprintf(stderr, "%02x", (hash[i])&0xff);
1575: fprintf(stderr, "\n");
1.98 markus 1576: #endif
1.108 markus 1577: /* save session id := H */
1578: /* XXX hashlen depends on KEX */
1579: session_id2_len = 20;
1580: session_id2 = xmalloc(session_id2_len);
1581: memcpy(session_id2, hash, session_id2_len);
1582:
1.98 markus 1583: /* sign H */
1.108 markus 1584: /* XXX hashlen depends on KEX */
1.134 markus 1585: key_sign(hostkey, &signature, &slen, hash, 20);
1.108 markus 1586:
1587: destroy_sensitive_data();
1.98 markus 1588:
1589: /* send server hostkey, DH pubkey 'f' and singed H */
1590: packet_start(SSH2_MSG_KEXDH_REPLY);
1591: packet_put_string((char *)server_host_key_blob, sbloblen);
1.114 markus 1592: packet_put_bignum2(dh->pub_key); /* f */
1.98 markus 1593: packet_put_string((char *)signature, slen);
1594: packet_send();
1.106 markus 1595: xfree(signature);
1.111 markus 1596: xfree(server_host_key_blob);
1.98 markus 1597: packet_write_wait();
1598:
1599: kex_derive_keys(kex, hash, shared_secret);
1.156 stevesk 1600: BN_clear_free(shared_secret);
1.98 markus 1601: packet_set_kex(kex);
1602:
1603: /* have keys, free DH */
1604: DH_free(dh);
1.129 provos 1605: }
1606:
1607: /* diffie-hellman-group-exchange-sha1 */
1.98 markus 1608:
1.129 provos 1609: void
1610: ssh_dhgex_server(Kex *kex, Buffer *client_kexinit, Buffer *server_kexinit)
1611: {
1.130 markus 1612: #ifdef DEBUG_KEXDH
1613: int i;
1614: #endif
1.129 provos 1615: int payload_len, dlen;
1616: int slen, nbits;
1.140 markus 1617: u_char *signature = NULL;
1618: u_char *server_host_key_blob = NULL;
1619: u_int sbloblen;
1620: u_int klen, kout;
1621: u_char *kbuf;
1622: u_char *hash;
1.129 provos 1623: BIGNUM *shared_secret = 0;
1624: DH *dh;
1625: BIGNUM *dh_client_pub = 0;
1.134 markus 1626: Key *hostkey;
1627:
1628: hostkey = get_hostkey_by_type(kex->hostkey_type);
1629: if (hostkey == NULL)
1630: fatal("Unsupported hostkey type %d", kex->hostkey_type);
1.129 provos 1631:
1632: /* KEXDHGEX */
1633: debug("Wait SSH2_MSG_KEX_DH_GEX_REQUEST.");
1634: packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_REQUEST);
1635: nbits = packet_get_int();
1636: dh = choose_dh(nbits);
1637:
1638: debug("Sending SSH2_MSG_KEX_DH_GEX_GROUP.");
1639: packet_start(SSH2_MSG_KEX_DH_GEX_GROUP);
1640: packet_put_bignum2(dh->p);
1641: packet_put_bignum2(dh->g);
1.98 markus 1642: packet_send();
1643: packet_write_wait();
1.139 provos 1644:
1645: /* Compute our exchange value in parallel with the client */
1646:
1.173 markus 1647: dh_gen_key(dh, kex->we_need * 8);
1.98 markus 1648:
1.129 provos 1649: debug("Wait SSH2_MSG_KEX_DH_GEX_INIT.");
1650: packet_read_expect(&payload_len, SSH2_MSG_KEX_DH_GEX_INIT);
1651:
1652: /* key, cert */
1653: dh_client_pub = BN_new();
1654: if (dh_client_pub == NULL)
1655: fatal("dh_client_pub == NULL");
1656: packet_get_bignum2(dh_client_pub, &dlen);
1657:
1658: #ifdef DEBUG_KEXDH
1659: fprintf(stderr, "\ndh_client_pub= ");
1660: BN_print_fp(stderr, dh_client_pub);
1661: fprintf(stderr, "\n");
1662: debug("bits %d", BN_num_bits(dh_client_pub));
1663: #endif
1664:
1665: #ifdef DEBUG_KEXDH
1666: fprintf(stderr, "\np= ");
1667: BN_print_fp(stderr, dh->p);
1668: fprintf(stderr, "\ng= ");
1669: bn_print(dh->g);
1670: fprintf(stderr, "\npub= ");
1671: BN_print_fp(stderr, dh->pub_key);
1672: fprintf(stderr, "\n");
1.161 stevesk 1673: DHparams_print_fp(stderr, dh);
1.129 provos 1674: #endif
1675: if (!dh_pub_is_valid(dh, dh_client_pub))
1676: packet_disconnect("bad client public DH value");
1677:
1678: klen = DH_size(dh);
1679: kbuf = xmalloc(klen);
1680: kout = DH_compute_key(kbuf, dh_client_pub, dh);
1681:
1682: #ifdef DEBUG_KEXDH
1683: debug("shared secret: len %d/%d", klen, kout);
1684: fprintf(stderr, "shared secret == ");
1685: for (i = 0; i< kout; i++)
1686: fprintf(stderr, "%02x", (kbuf[i])&0xff);
1687: fprintf(stderr, "\n");
1688: #endif
1689: shared_secret = BN_new();
1690:
1691: BN_bin2bn(kbuf, kout, shared_secret);
1692: memset(kbuf, 0, klen);
1693: xfree(kbuf);
1694:
1695: /* XXX precompute? */
1.134 markus 1696: key_to_blob(hostkey, &server_host_key_blob, &sbloblen);
1.98 markus 1697:
1.129 provos 1698: /* calc H */ /* XXX depends on 'kex' */
1699: hash = kex_hash_gex(
1700: client_version_string,
1701: server_version_string,
1702: buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1703: buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1704: (char *)server_host_key_blob, sbloblen,
1705: nbits, dh->p, dh->g,
1706: dh_client_pub,
1707: dh->pub_key,
1708: shared_secret
1709: );
1710: buffer_free(client_kexinit);
1711: buffer_free(server_kexinit);
1712: xfree(client_kexinit);
1713: xfree(server_kexinit);
1.156 stevesk 1714: BN_free(dh_client_pub);
1.100 markus 1715: #ifdef DEBUG_KEXDH
1.129 provos 1716: fprintf(stderr, "hash == ");
1717: for (i = 0; i< 20; i++)
1718: fprintf(stderr, "%02x", (hash[i])&0xff);
1719: fprintf(stderr, "\n");
1720: #endif
1721: /* save session id := H */
1722: /* XXX hashlen depends on KEX */
1723: session_id2_len = 20;
1724: session_id2 = xmalloc(session_id2_len);
1725: memcpy(session_id2, hash, session_id2_len);
1726:
1727: /* sign H */
1728: /* XXX hashlen depends on KEX */
1.134 markus 1729: key_sign(hostkey, &signature, &slen, hash, 20);
1.129 provos 1730:
1731: destroy_sensitive_data();
1732:
1733: /* send server hostkey, DH pubkey 'f' and singed H */
1734: packet_start(SSH2_MSG_KEX_DH_GEX_REPLY);
1735: packet_put_string((char *)server_host_key_blob, sbloblen);
1736: packet_put_bignum2(dh->pub_key); /* f */
1737: packet_put_string((char *)signature, slen);
1.98 markus 1738: packet_send();
1.129 provos 1739: xfree(signature);
1740: xfree(server_host_key_blob);
1.98 markus 1741: packet_write_wait();
1.129 provos 1742:
1743: kex_derive_keys(kex, hash, shared_secret);
1.156 stevesk 1744: BN_clear_free(shared_secret);
1.129 provos 1745: packet_set_kex(kex);
1746:
1747: /* have keys, free DH */
1748: DH_free(dh);
1.1 deraadt 1749: }
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