Annotation of src/usr.bin/ssh/sshd.c, Revision 1.114
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
5: * Created: Fri Mar 17 17:09:28 1995 ylo
6: * This program is the ssh daemon. It listens for connections from clients, and
7: * performs authentication, executes use commands or shell, and forwards
8: * information to/from the application to the user client over an encrypted
9: * connection. This can also handle forwarding of X11, TCP/IP, and authentication
10: * agent connections.
1.98 markus 11: *
12: * SSH2 implementation,
13: * Copyright (c) 2000 Markus Friedl. All rights reserved.
1.65 deraadt 14: */
1.1 deraadt 15:
16: #include "includes.h"
1.114 ! markus 17: RCSID("$OpenBSD: sshd.c,v 1.113 2000/05/01 20:34:51 markus Exp $");
1.1 deraadt 18:
19: #include "xmalloc.h"
20: #include "rsa.h"
21: #include "ssh.h"
22: #include "pty.h"
23: #include "packet.h"
24: #include "cipher.h"
25: #include "mpaux.h"
26: #include "servconf.h"
27: #include "uidswap.h"
1.33 markus 28: #include "compat.h"
1.96 markus 29: #include "buffer.h"
30:
1.98 markus 31: #include "ssh2.h"
1.104 markus 32: #include <openssl/dh.h>
33: #include <openssl/bn.h>
34: #include <openssl/hmac.h>
1.98 markus 35: #include "kex.h"
1.104 markus 36: #include <openssl/dsa.h>
37: #include <openssl/rsa.h>
1.96 markus 38: #include "key.h"
1.98 markus 39: #include "dsa.h"
1.96 markus 40:
41: #include "auth.h"
1.98 markus 42: #include "myproposal.h"
1.108 markus 43: #include "authfile.h"
1.1 deraadt 44:
45: #ifdef LIBWRAP
46: #include <tcpd.h>
47: #include <syslog.h>
48: int allow_severity = LOG_INFO;
49: int deny_severity = LOG_WARNING;
50: #endif /* LIBWRAP */
51:
52: #ifndef O_NOCTTY
53: #define O_NOCTTY 0
54: #endif
55:
56: /* Server configuration options. */
57: ServerOptions options;
58:
59: /* Name of the server configuration file. */
60: char *config_file_name = SERVER_CONFIG_FILE;
61:
1.105 markus 62: /*
1.75 markus 63: * Flag indicating whether IPv4 or IPv6. This can be set on the command line.
64: * Default value is AF_UNSPEC means both IPv4 and IPv6.
65: */
66: int IPv4or6 = AF_UNSPEC;
67:
1.65 deraadt 68: /*
69: * Debug mode flag. This can be set on the command line. If debug
70: * mode is enabled, extra debugging output will be sent to the system
71: * log, the daemon will not go to background, and will exit after processing
72: * the first connection.
73: */
1.1 deraadt 74: int debug_flag = 0;
75:
76: /* Flag indicating that the daemon is being started from inetd. */
77: int inetd_flag = 0;
78:
1.47 markus 79: /* debug goes to stderr unless inetd_flag is set */
80: int log_stderr = 0;
81:
1.1 deraadt 82: /* argv[0] without path. */
83: char *av0;
84:
85: /* Saved arguments to main(). */
86: char **saved_argv;
87:
1.66 markus 88: /*
1.75 markus 89: * The sockets that the server is listening; this is used in the SIGHUP
90: * signal handler.
1.66 markus 91: */
1.75 markus 92: #define MAX_LISTEN_SOCKS 16
93: int listen_socks[MAX_LISTEN_SOCKS];
94: int num_listen_socks = 0;
1.1 deraadt 95:
1.66 markus 96: /*
97: * the client's version string, passed by sshd2 in compat mode. if != NULL,
98: * sshd will skip the version-number exchange
99: */
1.61 markus 100: char *client_version_string = NULL;
1.96 markus 101: char *server_version_string = NULL;
1.1 deraadt 102:
1.66 markus 103: /*
104: * Any really sensitive data in the application is contained in this
105: * structure. The idea is that this structure could be locked into memory so
106: * that the pages do not get written into swap. However, there are some
107: * problems. The private key contains BIGNUMs, and we do not (in principle)
108: * have access to the internals of them, and locking just the structure is
109: * not very useful. Currently, memory locking is not implemented.
110: */
1.64 markus 111: struct {
1.108 markus 112: RSA *private_key; /* Private part of empheral server key. */
1.64 markus 113: RSA *host_key; /* Private part of host key. */
1.108 markus 114: Key *dsa_host_key; /* Private DSA host key. */
1.1 deraadt 115: } sensitive_data;
116:
1.66 markus 117: /*
118: * Flag indicating whether the current session key has been used. This flag
119: * is set whenever the key is used, and cleared when the key is regenerated.
120: */
1.1 deraadt 121: int key_used = 0;
122:
123: /* This is set to true when SIGHUP is received. */
124: int received_sighup = 0;
125:
126: /* Public side of the server key. This value is regenerated regularly with
127: the private key. */
1.2 provos 128: RSA *public_key;
1.1 deraadt 129:
1.96 markus 130: /* session identifier, used by RSA-auth */
131: unsigned char session_id[16];
132:
1.108 markus 133: /* same for ssh2 */
134: unsigned char *session_id2 = NULL;
135: int session_id2_len = 0;
136:
1.1 deraadt 137: /* Prototypes for various functions defined later in this file. */
1.96 markus 138: void do_ssh1_kex();
1.98 markus 139: void do_ssh2_kex();
1.87 markus 140:
141: /*
1.75 markus 142: * Close all listening sockets
143: */
144: void
145: close_listen_socks(void)
146: {
147: int i;
148: for (i = 0; i < num_listen_socks; i++)
149: close(listen_socks[i]);
150: num_listen_socks = -1;
151: }
152:
153: /*
1.65 deraadt 154: * Signal handler for SIGHUP. Sshd execs itself when it receives SIGHUP;
155: * the effect is to reread the configuration file (and to regenerate
156: * the server key).
157: */
1.105 markus 158: void
1.64 markus 159: sighup_handler(int sig)
1.1 deraadt 160: {
1.64 markus 161: received_sighup = 1;
162: signal(SIGHUP, sighup_handler);
1.1 deraadt 163: }
164:
1.65 deraadt 165: /*
166: * Called from the main program after receiving SIGHUP.
167: * Restarts the server.
168: */
1.105 markus 169: void
1.64 markus 170: sighup_restart()
1.1 deraadt 171: {
1.64 markus 172: log("Received SIGHUP; restarting.");
1.75 markus 173: close_listen_socks();
1.64 markus 174: execv(saved_argv[0], saved_argv);
175: log("RESTART FAILED: av0='%s', error: %s.", av0, strerror(errno));
176: exit(1);
1.1 deraadt 177: }
178:
1.65 deraadt 179: /*
180: * Generic signal handler for terminating signals in the master daemon.
181: * These close the listen socket; not closing it seems to cause "Address
182: * already in use" problems on some machines, which is inconvenient.
183: */
1.105 markus 184: void
1.64 markus 185: sigterm_handler(int sig)
1.1 deraadt 186: {
1.64 markus 187: log("Received signal %d; terminating.", sig);
1.75 markus 188: close_listen_socks();
1.113 markus 189: unlink(options.pid_file);
1.64 markus 190: exit(255);
1.1 deraadt 191: }
192:
1.65 deraadt 193: /*
194: * SIGCHLD handler. This is called whenever a child dies. This will then
195: * reap any zombies left by exited c.
196: */
1.105 markus 197: void
1.64 markus 198: main_sigchld_handler(int sig)
1.1 deraadt 199: {
1.64 markus 200: int save_errno = errno;
201: int status;
1.60 deraadt 202:
1.64 markus 203: while (waitpid(-1, &status, WNOHANG) > 0)
204: ;
1.60 deraadt 205:
1.64 markus 206: signal(SIGCHLD, main_sigchld_handler);
207: errno = save_errno;
1.1 deraadt 208: }
209:
1.65 deraadt 210: /*
211: * Signal handler for the alarm after the login grace period has expired.
212: */
1.105 markus 213: void
1.64 markus 214: grace_alarm_handler(int sig)
1.1 deraadt 215: {
1.64 markus 216: /* Close the connection. */
217: packet_close();
218:
219: /* Log error and exit. */
220: fatal("Timeout before authentication for %s.", get_remote_ipaddr());
1.62 markus 221: }
222:
1.65 deraadt 223: /*
224: * Signal handler for the key regeneration alarm. Note that this
225: * alarm only occurs in the daemon waiting for connections, and it does not
226: * do anything with the private key or random state before forking.
227: * Thus there should be no concurrency control/asynchronous execution
228: * problems.
229: */
1.108 markus 230: /* XXX do we really want this work to be done in a signal handler ? -m */
1.105 markus 231: void
1.64 markus 232: key_regeneration_alarm(int sig)
1.1 deraadt 233: {
1.64 markus 234: int save_errno = errno;
1.18 deraadt 235:
1.64 markus 236: /* Check if we should generate a new key. */
237: if (key_used) {
238: /* This should really be done in the background. */
239: log("Generating new %d bit RSA key.", options.server_key_bits);
240:
241: if (sensitive_data.private_key != NULL)
242: RSA_free(sensitive_data.private_key);
243: sensitive_data.private_key = RSA_new();
244:
245: if (public_key != NULL)
246: RSA_free(public_key);
247: public_key = RSA_new();
248:
249: rsa_generate_key(sensitive_data.private_key, public_key,
250: options.server_key_bits);
251: arc4random_stir();
252: key_used = 0;
253: log("RSA key generation complete.");
254: }
255: /* Reschedule the alarm. */
256: signal(SIGALRM, key_regeneration_alarm);
257: alarm(options.key_regeneration_time);
258: errno = save_errno;
1.1 deraadt 259: }
260:
1.98 markus 261: char *
262: chop(char *s)
263: {
1.105 markus 264: char *t = s;
265: while (*t) {
266: if(*t == '\n' || *t == '\r') {
267: *t = '\0';
268: return s;
269: }
270: t++;
271: }
272: return s;
1.98 markus 273:
274: }
275:
1.96 markus 276: void
277: sshd_exchange_identification(int sock_in, int sock_out)
278: {
1.102 markus 279: int i, mismatch;
1.96 markus 280: int remote_major, remote_minor;
1.102 markus 281: int major, minor;
1.96 markus 282: char *s;
283: char buf[256]; /* Must not be larger than remote_version. */
284: char remote_version[256]; /* Must be at least as big as buf. */
285:
1.103 markus 286: if ((options.protocol & SSH_PROTO_1) &&
287: (options.protocol & SSH_PROTO_2)) {
1.102 markus 288: major = PROTOCOL_MAJOR_1;
289: minor = 99;
290: } else if (options.protocol & SSH_PROTO_2) {
291: major = PROTOCOL_MAJOR_2;
292: minor = PROTOCOL_MINOR_2;
293: } else {
294: major = PROTOCOL_MAJOR_1;
295: minor = PROTOCOL_MINOR_1;
296: }
297: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n", major, minor, SSH_VERSION);
1.96 markus 298: server_version_string = xstrdup(buf);
299:
300: if (client_version_string == NULL) {
301: /* Send our protocol version identification. */
302: if (atomicio(write, sock_out, server_version_string, strlen(server_version_string))
303: != strlen(server_version_string)) {
304: log("Could not write ident string to %s.", get_remote_ipaddr());
305: fatal_cleanup();
306: }
307:
308: /* Read other side\'s version identification. */
309: for (i = 0; i < sizeof(buf) - 1; i++) {
310: if (read(sock_in, &buf[i], 1) != 1) {
311: log("Did not receive ident string from %s.", get_remote_ipaddr());
312: fatal_cleanup();
313: }
314: if (buf[i] == '\r') {
315: buf[i] = '\n';
316: buf[i + 1] = 0;
317: continue;
318: }
319: if (buf[i] == '\n') {
320: /* buf[i] == '\n' */
321: buf[i + 1] = 0;
322: break;
323: }
324: }
325: buf[sizeof(buf) - 1] = 0;
326: client_version_string = xstrdup(buf);
327: }
328:
329: /*
330: * Check that the versions match. In future this might accept
331: * several versions and set appropriate flags to handle them.
332: */
333: if (sscanf(client_version_string, "SSH-%d.%d-%[^\n]\n",
334: &remote_major, &remote_minor, remote_version) != 3) {
1.105 markus 335: s = "Protocol mismatch.\n";
1.96 markus 336: (void) atomicio(write, sock_out, s, strlen(s));
337: close(sock_in);
338: close(sock_out);
339: log("Bad protocol version identification '%.100s' from %s",
340: client_version_string, get_remote_ipaddr());
341: fatal_cleanup();
342: }
343: debug("Client protocol version %d.%d; client software version %.100s",
344: remote_major, remote_minor, remote_version);
345:
1.98 markus 346: compat_datafellows(remote_version);
347:
1.102 markus 348: mismatch = 0;
1.96 markus 349: switch(remote_major) {
350: case 1:
1.108 markus 351: if (remote_minor == 99) {
352: if (options.protocol & SSH_PROTO_2)
353: enable_compat20();
354: else
355: mismatch = 1;
356: break;
357: }
1.102 markus 358: if (!(options.protocol & SSH_PROTO_1)) {
359: mismatch = 1;
360: break;
361: }
1.96 markus 362: if (remote_minor < 3) {
363: packet_disconnect("Your ssh version is too old and"
364: "is no longer supported. Please install a newer version.");
365: } else if (remote_minor == 3) {
366: /* note that this disables agent-forwarding */
367: enable_compat13();
368: }
1.102 markus 369: break;
1.98 markus 370: case 2:
1.102 markus 371: if (options.protocol & SSH_PROTO_2) {
1.98 markus 372: enable_compat20();
373: break;
374: }
1.99 markus 375: /* FALLTHROUGH */
1.105 markus 376: default:
1.102 markus 377: mismatch = 1;
378: break;
379: }
380: chop(server_version_string);
381: chop(client_version_string);
382: debug("Local version string %.200s", server_version_string);
383:
384: if (mismatch) {
1.96 markus 385: s = "Protocol major versions differ.\n";
386: (void) atomicio(write, sock_out, s, strlen(s));
387: close(sock_in);
388: close(sock_out);
1.102 markus 389: log("Protocol major versions differ for %s: %.200s vs. %.200s",
390: get_remote_ipaddr(),
391: server_version_string, client_version_string);
1.96 markus 392: fatal_cleanup();
393: }
1.108 markus 394: if (compat20)
395: packet_set_ssh2_format();
396: }
397:
398:
399: void
400: destroy_sensitive_data(void)
401: {
402: /* Destroy the private and public keys. They will no longer be needed. */
403: RSA_free(public_key);
404: RSA_free(sensitive_data.private_key);
405: RSA_free(sensitive_data.host_key);
406: if (sensitive_data.dsa_host_key != NULL)
407: key_free(sensitive_data.dsa_host_key);
1.96 markus 408: }
409:
1.65 deraadt 410: /*
411: * Main program for the daemon.
412: */
1.2 provos 413: int
414: main(int ac, char **av)
1.1 deraadt 415: {
1.64 markus 416: extern char *optarg;
417: extern int optind;
1.107 deraadt 418: int opt, sock_in = 0, sock_out = 0, newsock, i, fdsetsz, on = 1;
419: pid_t pid;
1.75 markus 420: socklen_t fromlen;
1.110 markus 421: int silent = 0;
1.75 markus 422: fd_set *fdset;
423: struct sockaddr_storage from;
1.64 markus 424: const char *remote_ip;
425: int remote_port;
426: FILE *f;
427: struct linger linger;
1.75 markus 428: struct addrinfo *ai;
429: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
430: int listen_sock, maxfd;
1.64 markus 431:
432: /* Save argv[0]. */
433: saved_argv = av;
434: if (strchr(av[0], '/'))
435: av0 = strrchr(av[0], '/') + 1;
436: else
437: av0 = av[0];
438:
439: /* Initialize configuration options to their default values. */
440: initialize_server_options(&options);
441:
442: /* Parse command-line arguments. */
1.102 markus 443: while ((opt = getopt(ac, av, "f:p:b:k:h:g:V:diqQ46")) != EOF) {
1.64 markus 444: switch (opt) {
1.75 markus 445: case '4':
446: IPv4or6 = AF_INET;
447: break;
448: case '6':
449: IPv4or6 = AF_INET6;
450: break;
1.64 markus 451: case 'f':
452: config_file_name = optarg;
453: break;
454: case 'd':
455: debug_flag = 1;
456: options.log_level = SYSLOG_LEVEL_DEBUG;
457: break;
458: case 'i':
459: inetd_flag = 1;
460: break;
461: case 'Q':
1.110 markus 462: silent = 1;
1.64 markus 463: break;
464: case 'q':
465: options.log_level = SYSLOG_LEVEL_QUIET;
466: break;
467: case 'b':
468: options.server_key_bits = atoi(optarg);
469: break;
470: case 'p':
1.75 markus 471: options.ports_from_cmdline = 1;
472: if (options.num_ports >= MAX_PORTS)
473: fatal("too many ports.\n");
474: options.ports[options.num_ports++] = atoi(optarg);
1.64 markus 475: break;
476: case 'g':
477: options.login_grace_time = atoi(optarg);
478: break;
479: case 'k':
480: options.key_regeneration_time = atoi(optarg);
481: break;
482: case 'h':
483: options.host_key_file = optarg;
484: break;
485: case 'V':
486: client_version_string = optarg;
487: /* only makes sense with inetd_flag, i.e. no listen() */
488: inetd_flag = 1;
489: break;
490: case '?':
491: default:
492: fprintf(stderr, "sshd version %s\n", SSH_VERSION);
493: fprintf(stderr, "Usage: %s [options]\n", av0);
494: fprintf(stderr, "Options:\n");
1.66 markus 495: fprintf(stderr, " -f file Configuration file (default %s)\n", SERVER_CONFIG_FILE);
1.64 markus 496: fprintf(stderr, " -d Debugging mode\n");
497: fprintf(stderr, " -i Started from inetd\n");
498: fprintf(stderr, " -q Quiet (no logging)\n");
499: fprintf(stderr, " -p port Listen on the specified port (default: 22)\n");
500: fprintf(stderr, " -k seconds Regenerate server key every this many seconds (default: 3600)\n");
501: fprintf(stderr, " -g seconds Grace period for authentication (default: 300)\n");
502: fprintf(stderr, " -b bits Size of server RSA key (default: 768 bits)\n");
503: fprintf(stderr, " -h file File from which to read host key (default: %s)\n",
1.75 markus 504: HOST_KEY_FILE);
505: fprintf(stderr, " -4 Use IPv4 only\n");
506: fprintf(stderr, " -6 Use IPv6 only\n");
1.64 markus 507: exit(1);
508: }
509: }
510:
1.75 markus 511: /*
512: * Force logging to stderr until we have loaded the private host
513: * key (unless started from inetd)
514: */
515: log_init(av0,
516: options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
517: options.log_facility == -1 ? SYSLOG_FACILITY_AUTH : options.log_facility,
1.110 markus 518: !silent && !inetd_flag);
1.75 markus 519:
1.64 markus 520: /* Read server configuration options from the configuration file. */
521: read_server_config(&options, config_file_name);
522:
523: /* Fill in default values for those options not explicitly set. */
524: fill_default_server_options(&options);
525:
526: /* Check that there are no remaining arguments. */
527: if (optind < ac) {
528: fprintf(stderr, "Extra argument %s.\n", av[optind]);
529: exit(1);
530: }
531:
532: debug("sshd version %.100s", SSH_VERSION);
533:
1.108 markus 534: sensitive_data.dsa_host_key = NULL;
535: sensitive_data.host_key = NULL;
536:
537: /* check if RSA support exists */
538: if ((options.protocol & SSH_PROTO_1) &&
539: rsa_alive() == 0) {
540: log("no RSA support in libssl and libcrypto. See ssl(8)");
541: log("Disabling protocol version 1");
542: options.protocol &= ~SSH_PROTO_1;
543: }
544: /* Load the RSA/DSA host key. It must have empty passphrase. */
545: if (options.protocol & SSH_PROTO_1) {
546: Key k;
547: sensitive_data.host_key = RSA_new();
548: k.type = KEY_RSA;
549: k.rsa = sensitive_data.host_key;
550: errno = 0;
1.109 markus 551: if (!load_private_key(options.host_key_file, "", &k, NULL)) {
1.108 markus 552: error("Could not load host key: %.200s: %.100s",
553: options.host_key_file, strerror(errno));
554: log("Disabling protocol version 1");
555: options.protocol &= ~SSH_PROTO_1;
556: }
557: k.rsa = NULL;
558: }
559: if (options.protocol & SSH_PROTO_2) {
560: sensitive_data.dsa_host_key = key_new(KEY_DSA);
561: if (!load_private_key(options.dsa_key_file, "", sensitive_data.dsa_host_key, NULL)) {
562: error("Could not load DSA host key: %.200s", options.dsa_key_file);
563: log("Disabling protocol version 2");
564: options.protocol &= ~SSH_PROTO_2;
565: }
566: }
567: if (! options.protocol & (SSH_PROTO_1|SSH_PROTO_2)) {
1.110 markus 568: if (silent == 0)
569: fprintf(stderr, "sshd: no hostkeys available -- exiting.\n");
1.108 markus 570: log("sshd: no hostkeys available -- exiting.\n");
1.64 markus 571: exit(1);
572: }
573:
1.108 markus 574: /* Check certain values for sanity. */
575: if (options.protocol & SSH_PROTO_1) {
576: if (options.server_key_bits < 512 ||
577: options.server_key_bits > 32768) {
578: fprintf(stderr, "Bad server key size.\n");
579: exit(1);
580: }
581: /*
582: * Check that server and host key lengths differ sufficiently. This
583: * is necessary to make double encryption work with rsaref. Oh, I
584: * hate software patents. I dont know if this can go? Niels
585: */
586: if (options.server_key_bits >
587: BN_num_bits(sensitive_data.host_key->n) - SSH_KEY_BITS_RESERVED &&
588: options.server_key_bits <
589: BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) {
590: options.server_key_bits =
591: BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED;
592: debug("Forcing server key to %d bits to make it differ from host key.",
593: options.server_key_bits);
594: }
595: }
596:
597: /* Initialize the log (it is reinitialized below in case we forked). */
1.64 markus 598: if (debug_flag && !inetd_flag)
599: log_stderr = 1;
600: log_init(av0, options.log_level, options.log_facility, log_stderr);
601:
1.108 markus 602: /*
603: * If not in debugging mode, and not started from inetd, disconnect
604: * from the controlling terminal, and fork. The original process
605: * exits.
606: */
1.64 markus 607: if (!debug_flag && !inetd_flag) {
1.1 deraadt 608: #ifdef TIOCNOTTY
1.64 markus 609: int fd;
1.1 deraadt 610: #endif /* TIOCNOTTY */
1.64 markus 611: if (daemon(0, 0) < 0)
612: fatal("daemon() failed: %.200s", strerror(errno));
613:
614: /* Disconnect from the controlling tty. */
1.1 deraadt 615: #ifdef TIOCNOTTY
1.64 markus 616: fd = open("/dev/tty", O_RDWR | O_NOCTTY);
617: if (fd >= 0) {
618: (void) ioctl(fd, TIOCNOTTY, NULL);
619: close(fd);
620: }
621: #endif /* TIOCNOTTY */
622: }
623: /* Reinitialize the log (because of the fork above). */
624: log_init(av0, options.log_level, options.log_facility, log_stderr);
625:
626: /* Do not display messages to stdout in RSA code. */
627: rsa_set_verbose(0);
628:
629: /* Initialize the random number generator. */
630: arc4random_stir();
631:
632: /* Chdir to the root directory so that the current disk can be
633: unmounted if desired. */
634: chdir("/");
635:
636: /* Start listening for a socket, unless started from inetd. */
637: if (inetd_flag) {
638: int s1, s2;
639: s1 = dup(0); /* Make sure descriptors 0, 1, and 2 are in use. */
640: s2 = dup(s1);
641: sock_in = dup(0);
642: sock_out = dup(1);
1.108 markus 643: /*
644: * We intentionally do not close the descriptors 0, 1, and 2
645: * as our code for setting the descriptors won\'t work if
646: * ttyfd happens to be one of those.
647: */
1.64 markus 648: debug("inetd sockets after dupping: %d, %d", sock_in, sock_out);
649:
1.108 markus 650: if (options.protocol & SSH_PROTO_1) {
651: public_key = RSA_new();
652: sensitive_data.private_key = RSA_new();
653: log("Generating %d bit RSA key.", options.server_key_bits);
654: rsa_generate_key(sensitive_data.private_key, public_key,
655: options.server_key_bits);
656: arc4random_stir();
657: log("RSA key generation complete.");
658: }
1.64 markus 659: } else {
1.75 markus 660: for (ai = options.listen_addrs; ai; ai = ai->ai_next) {
661: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
662: continue;
663: if (num_listen_socks >= MAX_LISTEN_SOCKS)
664: fatal("Too many listen sockets. "
665: "Enlarge MAX_LISTEN_SOCKS");
666: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
667: ntop, sizeof(ntop), strport, sizeof(strport),
668: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
669: error("getnameinfo failed");
670: continue;
671: }
672: /* Create socket for listening. */
673: listen_sock = socket(ai->ai_family, SOCK_STREAM, 0);
674: if (listen_sock < 0) {
675: /* kernel may not support ipv6 */
676: verbose("socket: %.100s", strerror(errno));
677: continue;
678: }
679: if (fcntl(listen_sock, F_SETFL, O_NONBLOCK) < 0) {
680: error("listen_sock O_NONBLOCK: %s", strerror(errno));
681: close(listen_sock);
682: continue;
683: }
684: /*
685: * Set socket options. We try to make the port
686: * reusable and have it close as fast as possible
687: * without waiting in unnecessary wait states on
688: * close.
689: */
690: setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR,
691: (void *) &on, sizeof(on));
692: linger.l_onoff = 1;
693: linger.l_linger = 5;
694: setsockopt(listen_sock, SOL_SOCKET, SO_LINGER,
695: (void *) &linger, sizeof(linger));
696:
697: debug("Bind to port %s on %s.", strport, ntop);
698:
699: /* Bind the socket to the desired port. */
700: if (bind(listen_sock, ai->ai_addr, ai->ai_addrlen) < 0) {
701: error("Bind to port %s on %s failed: %.200s.",
702: strport, ntop, strerror(errno));
703: close(listen_sock);
704: continue;
705: }
706: listen_socks[num_listen_socks] = listen_sock;
707: num_listen_socks++;
708:
709: /* Start listening on the port. */
710: log("Server listening on %s port %s.", ntop, strport);
711: if (listen(listen_sock, 5) < 0)
712: fatal("listen: %.100s", strerror(errno));
713:
1.64 markus 714: }
1.75 markus 715: freeaddrinfo(options.listen_addrs);
716:
717: if (!num_listen_socks)
718: fatal("Cannot bind any address.");
719:
1.64 markus 720: if (!debug_flag) {
1.66 markus 721: /*
722: * Record our pid in /etc/sshd_pid to make it easier
723: * to kill the correct sshd. We don\'t want to do
724: * this before the bind above because the bind will
725: * fail if there already is a daemon, and this will
726: * overwrite any old pid in the file.
727: */
1.112 markus 728: f = fopen(options.pid_file, "w");
1.64 markus 729: if (f) {
730: fprintf(f, "%u\n", (unsigned int) getpid());
731: fclose(f);
732: }
733: }
1.108 markus 734: if (options.protocol & SSH_PROTO_1) {
735: public_key = RSA_new();
736: sensitive_data.private_key = RSA_new();
737:
738: log("Generating %d bit RSA key.", options.server_key_bits);
739: rsa_generate_key(sensitive_data.private_key, public_key,
740: options.server_key_bits);
741: arc4random_stir();
742: log("RSA key generation complete.");
1.64 markus 743:
1.108 markus 744: /* Schedule server key regeneration alarm. */
745: signal(SIGALRM, key_regeneration_alarm);
746: alarm(options.key_regeneration_time);
747: }
1.64 markus 748:
749: /* Arrange to restart on SIGHUP. The handler needs listen_sock. */
750: signal(SIGHUP, sighup_handler);
751: signal(SIGTERM, sigterm_handler);
752: signal(SIGQUIT, sigterm_handler);
753:
754: /* Arrange SIGCHLD to be caught. */
755: signal(SIGCHLD, main_sigchld_handler);
756:
1.75 markus 757: /* setup fd set for listen */
758: maxfd = 0;
759: for (i = 0; i < num_listen_socks; i++)
760: if (listen_socks[i] > maxfd)
761: maxfd = listen_socks[i];
1.105 markus 762: fdsetsz = howmany(maxfd, NFDBITS) * sizeof(fd_mask);
763: fdset = (fd_set *)xmalloc(fdsetsz);
1.75 markus 764:
1.66 markus 765: /*
766: * Stay listening for connections until the system crashes or
767: * the daemon is killed with a signal.
768: */
1.64 markus 769: for (;;) {
770: if (received_sighup)
771: sighup_restart();
1.75 markus 772: /* Wait in select until there is a connection. */
773: memset(fdset, 0, fdsetsz);
774: for (i = 0; i < num_listen_socks; i++)
775: FD_SET(listen_socks[i], fdset);
776: if (select(maxfd + 1, fdset, NULL, NULL, NULL) < 0) {
777: if (errno != EINTR)
778: error("select: %.100s", strerror(errno));
779: continue;
780: }
781: for (i = 0; i < num_listen_socks; i++) {
782: if (!FD_ISSET(listen_socks[i], fdset))
1.70 provos 783: continue;
1.75 markus 784: fromlen = sizeof(from);
785: newsock = accept(listen_socks[i], (struct sockaddr *)&from,
786: &fromlen);
787: if (newsock < 0) {
788: if (errno != EINTR && errno != EWOULDBLOCK)
789: error("accept: %.100s", strerror(errno));
790: continue;
1.70 provos 791: }
1.75 markus 792: if (fcntl(newsock, F_SETFL, 0) < 0) {
793: error("newsock del O_NONBLOCK: %s", strerror(errno));
1.64 markus 794: continue;
795: }
1.66 markus 796: /*
797: * Got connection. Fork a child to handle it, unless
798: * we are in debugging mode.
799: */
1.64 markus 800: if (debug_flag) {
1.66 markus 801: /*
802: * In debugging mode. Close the listening
803: * socket, and start processing the
804: * connection without forking.
805: */
1.64 markus 806: debug("Server will not fork when running in debugging mode.");
1.75 markus 807: close_listen_socks();
1.64 markus 808: sock_in = newsock;
809: sock_out = newsock;
810: pid = getpid();
811: break;
812: } else {
1.66 markus 813: /*
814: * Normal production daemon. Fork, and have
815: * the child process the connection. The
816: * parent continues listening.
817: */
1.64 markus 818: if ((pid = fork()) == 0) {
1.66 markus 819: /*
820: * Child. Close the listening socket, and start using the
821: * accepted socket. Reinitialize logging (since our pid has
822: * changed). We break out of the loop to handle the connection.
823: */
1.75 markus 824: close_listen_socks();
1.64 markus 825: sock_in = newsock;
826: sock_out = newsock;
827: log_init(av0, options.log_level, options.log_facility, log_stderr);
828: break;
829: }
830: }
831:
832: /* Parent. Stay in the loop. */
833: if (pid < 0)
834: error("fork: %.100s", strerror(errno));
835: else
836: debug("Forked child %d.", pid);
1.1 deraadt 837:
1.64 markus 838: /* Mark that the key has been used (it was "given" to the child). */
839: key_used = 1;
1.1 deraadt 840:
1.64 markus 841: arc4random_stir();
1.1 deraadt 842:
1.64 markus 843: /* Close the new socket (the child is now taking care of it). */
844: close(newsock);
1.75 markus 845: } /* for (i = 0; i < num_listen_socks; i++) */
846: /* child process check (or debug mode) */
847: if (num_listen_socks < 0)
848: break;
1.64 markus 849: }
1.1 deraadt 850: }
851:
1.64 markus 852: /* This is the child processing a new connection. */
853:
1.66 markus 854: /*
855: * Disable the key regeneration alarm. We will not regenerate the
856: * key since we are no longer in a position to give it to anyone. We
857: * will not restart on SIGHUP since it no longer makes sense.
858: */
1.64 markus 859: alarm(0);
860: signal(SIGALRM, SIG_DFL);
861: signal(SIGHUP, SIG_DFL);
862: signal(SIGTERM, SIG_DFL);
863: signal(SIGQUIT, SIG_DFL);
864: signal(SIGCHLD, SIG_DFL);
865:
1.66 markus 866: /*
867: * Set socket options for the connection. We want the socket to
868: * close as fast as possible without waiting for anything. If the
869: * connection is not a socket, these will do nothing.
870: */
871: /* setsockopt(sock_in, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.64 markus 872: linger.l_onoff = 1;
873: linger.l_linger = 5;
874: setsockopt(sock_in, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
875:
1.66 markus 876: /*
877: * Register our connection. This turns encryption off because we do
878: * not have a key.
879: */
1.64 markus 880: packet_set_connection(sock_in, sock_out);
1.1 deraadt 881:
1.64 markus 882: remote_port = get_remote_port();
883: remote_ip = get_remote_ipaddr();
1.52 markus 884:
1.64 markus 885: /* Check whether logins are denied from this host. */
1.37 dugsong 886: #ifdef LIBWRAP
1.75 markus 887: /* XXX LIBWRAP noes not know about IPv6 */
1.64 markus 888: {
889: struct request_info req;
1.37 dugsong 890:
1.64 markus 891: request_init(&req, RQ_DAEMON, av0, RQ_FILE, sock_in, NULL);
892: fromhost(&req);
1.37 dugsong 893:
1.64 markus 894: if (!hosts_access(&req)) {
895: close(sock_in);
896: close(sock_out);
897: refuse(&req);
898: }
1.75 markus 899: /*XXX IPv6 verbose("Connection from %.500s port %d", eval_client(&req), remote_port); */
1.64 markus 900: }
1.75 markus 901: #endif /* LIBWRAP */
1.64 markus 902: /* Log the connection. */
903: verbose("Connection from %.500s port %d", remote_ip, remote_port);
1.1 deraadt 904:
1.66 markus 905: /*
906: * We don\'t want to listen forever unless the other side
907: * successfully authenticates itself. So we set up an alarm which is
908: * cleared after successful authentication. A limit of zero
909: * indicates no limit. Note that we don\'t set the alarm in debugging
910: * mode; it is just annoying to have the server exit just when you
911: * are about to discover the bug.
912: */
1.64 markus 913: signal(SIGALRM, grace_alarm_handler);
914: if (!debug_flag)
915: alarm(options.login_grace_time);
916:
1.96 markus 917: sshd_exchange_identification(sock_in, sock_out);
1.66 markus 918: /*
919: * Check that the connection comes from a privileged port. Rhosts-
920: * and Rhosts-RSA-Authentication only make sense from priviledged
921: * programs. Of course, if the intruder has root access on his local
922: * machine, he can connect from any port. So do not use these
923: * authentication methods from machines that you do not trust.
924: */
1.64 markus 925: if (remote_port >= IPPORT_RESERVED ||
926: remote_port < IPPORT_RESERVED / 2) {
927: options.rhosts_authentication = 0;
928: options.rhosts_rsa_authentication = 0;
929: }
1.76 markus 930: #ifdef KRB4
931: if (!packet_connection_is_ipv4() &&
932: options.kerberos_authentication) {
933: debug("Kerberos Authentication disabled, only available for IPv4.");
934: options.kerberos_authentication = 0;
935: }
936: #endif /* KRB4 */
937:
1.64 markus 938: packet_set_nonblocking();
1.1 deraadt 939:
1.77 markus 940: /* perform the key exchange */
941: /* authenticate user and start session */
1.98 markus 942: if (compat20) {
943: do_ssh2_kex();
944: do_authentication2();
945: } else {
946: do_ssh1_kex();
947: do_authentication();
948: }
1.1 deraadt 949:
950: #ifdef KRB4
1.64 markus 951: /* Cleanup user's ticket cache file. */
952: if (options.kerberos_ticket_cleanup)
953: (void) dest_tkt();
1.1 deraadt 954: #endif /* KRB4 */
955:
1.64 markus 956: /* The connection has been terminated. */
957: verbose("Closing connection to %.100s", remote_ip);
958: packet_close();
959: exit(0);
1.1 deraadt 960: }
961:
1.65 deraadt 962: /*
1.77 markus 963: * SSH1 key exchange
1.65 deraadt 964: */
1.52 markus 965: void
1.96 markus 966: do_ssh1_kex()
1.1 deraadt 967: {
1.64 markus 968: int i, len;
1.77 markus 969: int plen, slen;
1.64 markus 970: BIGNUM *session_key_int;
971: unsigned char session_key[SSH_SESSION_KEY_LENGTH];
1.77 markus 972: unsigned char cookie[8];
1.64 markus 973: unsigned int cipher_type, auth_mask, protocol_flags;
974: u_int32_t rand = 0;
975:
1.66 markus 976: /*
977: * Generate check bytes that the client must send back in the user
978: * packet in order for it to be accepted; this is used to defy ip
979: * spoofing attacks. Note that this only works against somebody
980: * doing IP spoofing from a remote machine; any machine on the local
981: * network can still see outgoing packets and catch the random
982: * cookie. This only affects rhosts authentication, and this is one
983: * of the reasons why it is inherently insecure.
984: */
1.64 markus 985: for (i = 0; i < 8; i++) {
986: if (i % 4 == 0)
987: rand = arc4random();
1.77 markus 988: cookie[i] = rand & 0xff;
1.64 markus 989: rand >>= 8;
990: }
991:
1.66 markus 992: /*
993: * Send our public key. We include in the packet 64 bits of random
994: * data that must be matched in the reply in order to prevent IP
995: * spoofing.
996: */
1.64 markus 997: packet_start(SSH_SMSG_PUBLIC_KEY);
998: for (i = 0; i < 8; i++)
1.77 markus 999: packet_put_char(cookie[i]);
1.64 markus 1000:
1001: /* Store our public server RSA key. */
1002: packet_put_int(BN_num_bits(public_key->n));
1003: packet_put_bignum(public_key->e);
1004: packet_put_bignum(public_key->n);
1005:
1006: /* Store our public host RSA key. */
1007: packet_put_int(BN_num_bits(sensitive_data.host_key->n));
1008: packet_put_bignum(sensitive_data.host_key->e);
1009: packet_put_bignum(sensitive_data.host_key->n);
1010:
1011: /* Put protocol flags. */
1012: packet_put_int(SSH_PROTOFLAG_HOST_IN_FWD_OPEN);
1013:
1014: /* Declare which ciphers we support. */
1.97 markus 1015: packet_put_int(cipher_mask1());
1.64 markus 1016:
1017: /* Declare supported authentication types. */
1018: auth_mask = 0;
1019: if (options.rhosts_authentication)
1020: auth_mask |= 1 << SSH_AUTH_RHOSTS;
1021: if (options.rhosts_rsa_authentication)
1022: auth_mask |= 1 << SSH_AUTH_RHOSTS_RSA;
1023: if (options.rsa_authentication)
1024: auth_mask |= 1 << SSH_AUTH_RSA;
1.1 deraadt 1025: #ifdef KRB4
1.64 markus 1026: if (options.kerberos_authentication)
1027: auth_mask |= 1 << SSH_AUTH_KERBEROS;
1.1 deraadt 1028: #endif
1.5 dugsong 1029: #ifdef AFS
1.64 markus 1030: if (options.kerberos_tgt_passing)
1031: auth_mask |= 1 << SSH_PASS_KERBEROS_TGT;
1032: if (options.afs_token_passing)
1033: auth_mask |= 1 << SSH_PASS_AFS_TOKEN;
1.1 deraadt 1034: #endif
1.63 markus 1035: #ifdef SKEY
1.64 markus 1036: if (options.skey_authentication == 1)
1037: auth_mask |= 1 << SSH_AUTH_TIS;
1.63 markus 1038: #endif
1.64 markus 1039: if (options.password_authentication)
1040: auth_mask |= 1 << SSH_AUTH_PASSWORD;
1041: packet_put_int(auth_mask);
1042:
1043: /* Send the packet and wait for it to be sent. */
1044: packet_send();
1045: packet_write_wait();
1046:
1047: debug("Sent %d bit public key and %d bit host key.",
1048: BN_num_bits(public_key->n), BN_num_bits(sensitive_data.host_key->n));
1049:
1050: /* Read clients reply (cipher type and session key). */
1051: packet_read_expect(&plen, SSH_CMSG_SESSION_KEY);
1052:
1.69 markus 1053: /* Get cipher type and check whether we accept this. */
1.64 markus 1054: cipher_type = packet_get_char();
1.69 markus 1055:
1.105 markus 1056: if (!(cipher_mask() & (1 << cipher_type)))
1.69 markus 1057: packet_disconnect("Warning: client selects unsupported cipher.");
1.64 markus 1058:
1059: /* Get check bytes from the packet. These must match those we
1060: sent earlier with the public key packet. */
1061: for (i = 0; i < 8; i++)
1.77 markus 1062: if (cookie[i] != packet_get_char())
1.64 markus 1063: packet_disconnect("IP Spoofing check bytes do not match.");
1064:
1065: debug("Encryption type: %.200s", cipher_name(cipher_type));
1066:
1067: /* Get the encrypted integer. */
1068: session_key_int = BN_new();
1069: packet_get_bignum(session_key_int, &slen);
1070:
1071: protocol_flags = packet_get_int();
1072: packet_set_protocol_flags(protocol_flags);
1073:
1074: packet_integrity_check(plen, 1 + 8 + slen + 4, SSH_CMSG_SESSION_KEY);
1075:
1.66 markus 1076: /*
1077: * Decrypt it using our private server key and private host key (key
1078: * with larger modulus first).
1079: */
1.64 markus 1080: if (BN_cmp(sensitive_data.private_key->n, sensitive_data.host_key->n) > 0) {
1081: /* Private key has bigger modulus. */
1082: if (BN_num_bits(sensitive_data.private_key->n) <
1083: BN_num_bits(sensitive_data.host_key->n) + SSH_KEY_BITS_RESERVED) {
1084: fatal("do_connection: %s: private_key %d < host_key %d + SSH_KEY_BITS_RESERVED %d",
1085: get_remote_ipaddr(),
1086: BN_num_bits(sensitive_data.private_key->n),
1087: BN_num_bits(sensitive_data.host_key->n),
1088: SSH_KEY_BITS_RESERVED);
1089: }
1090: rsa_private_decrypt(session_key_int, session_key_int,
1091: sensitive_data.private_key);
1092: rsa_private_decrypt(session_key_int, session_key_int,
1093: sensitive_data.host_key);
1094: } else {
1095: /* Host key has bigger modulus (or they are equal). */
1096: if (BN_num_bits(sensitive_data.host_key->n) <
1097: BN_num_bits(sensitive_data.private_key->n) + SSH_KEY_BITS_RESERVED) {
1098: fatal("do_connection: %s: host_key %d < private_key %d + SSH_KEY_BITS_RESERVED %d",
1099: get_remote_ipaddr(),
1100: BN_num_bits(sensitive_data.host_key->n),
1101: BN_num_bits(sensitive_data.private_key->n),
1102: SSH_KEY_BITS_RESERVED);
1103: }
1104: rsa_private_decrypt(session_key_int, session_key_int,
1105: sensitive_data.host_key);
1106: rsa_private_decrypt(session_key_int, session_key_int,
1107: sensitive_data.private_key);
1108: }
1109:
1.77 markus 1110: compute_session_id(session_id, cookie,
1.64 markus 1111: sensitive_data.host_key->n,
1112: sensitive_data.private_key->n);
1113:
1.77 markus 1114: /* Destroy the private and public keys. They will no longer be needed. */
1.108 markus 1115: destroy_sensitive_data();
1.77 markus 1116:
1.66 markus 1117: /*
1118: * Extract session key from the decrypted integer. The key is in the
1119: * least significant 256 bits of the integer; the first byte of the
1120: * key is in the highest bits.
1121: */
1.64 markus 1122: BN_mask_bits(session_key_int, sizeof(session_key) * 8);
1123: len = BN_num_bytes(session_key_int);
1124: if (len < 0 || len > sizeof(session_key))
1125: fatal("do_connection: bad len from %s: session_key_int %d > sizeof(session_key) %d",
1126: get_remote_ipaddr(),
1127: len, sizeof(session_key));
1128: memset(session_key, 0, sizeof(session_key));
1129: BN_bn2bin(session_key_int, session_key + sizeof(session_key) - len);
1130:
1.77 markus 1131: /* Destroy the decrypted integer. It is no longer needed. */
1132: BN_clear_free(session_key_int);
1133:
1.64 markus 1134: /* Xor the first 16 bytes of the session key with the session id. */
1135: for (i = 0; i < 16; i++)
1136: session_key[i] ^= session_id[i];
1137:
1138: /* Set the session key. From this on all communications will be encrypted. */
1139: packet_set_encryption_key(session_key, SSH_SESSION_KEY_LENGTH, cipher_type);
1140:
1141: /* Destroy our copy of the session key. It is no longer needed. */
1142: memset(session_key, 0, sizeof(session_key));
1143:
1144: debug("Received session key; encryption turned on.");
1145:
1146: /* Send an acknowledgement packet. Note that this packet is sent encrypted. */
1147: packet_start(SSH_SMSG_SUCCESS);
1148: packet_send();
1149: packet_write_wait();
1.98 markus 1150: }
1151:
1152: /*
1153: * SSH2 key exchange: diffie-hellman-group1-sha1
1154: */
1155: void
1156: do_ssh2_kex()
1157: {
1158: Buffer *server_kexinit;
1159: Buffer *client_kexinit;
1160: int payload_len, dlen;
1161: int slen;
1162: unsigned int klen, kout;
1163: char *ptr;
1164: unsigned char *signature = NULL;
1165: unsigned char *server_host_key_blob = NULL;
1166: unsigned int sbloblen;
1167: DH *dh;
1168: BIGNUM *dh_client_pub = 0;
1169: BIGNUM *shared_secret = 0;
1170: int i;
1171: unsigned char *kbuf;
1172: unsigned char *hash;
1173: Kex *kex;
1174: char *cprop[PROPOSAL_MAX];
1175: char *sprop[PROPOSAL_MAX];
1176:
1177: /* KEXINIT */
1.102 markus 1178:
1179: if (options.ciphers != NULL) {
1.105 markus 1180: myproposal[PROPOSAL_ENC_ALGS_CTOS] =
1.102 markus 1181: myproposal[PROPOSAL_ENC_ALGS_STOC] = options.ciphers;
1182: }
1.98 markus 1183:
1184: debug("Sending KEX init.");
1185:
1186: for (i = 0; i < PROPOSAL_MAX; i++)
1187: sprop[i] = xstrdup(myproposal[i]);
1188: server_kexinit = kex_init(sprop);
1189: packet_start(SSH2_MSG_KEXINIT);
1190: packet_put_raw(buffer_ptr(server_kexinit), buffer_len(server_kexinit));
1191: packet_send();
1192: packet_write_wait();
1193:
1194: debug("done");
1195:
1196: packet_read_expect(&payload_len, SSH2_MSG_KEXINIT);
1197:
1198: /*
1199: * save raw KEXINIT payload in buffer. this is used during
1200: * computation of the session_id and the session keys.
1201: */
1202: client_kexinit = xmalloc(sizeof(*client_kexinit));
1203: buffer_init(client_kexinit);
1204: ptr = packet_get_raw(&payload_len);
1205: buffer_append(client_kexinit, ptr, payload_len);
1206:
1207: /* skip cookie */
1208: for (i = 0; i < 16; i++)
1209: (void) packet_get_char();
1210: /* save kex init proposal strings */
1211: for (i = 0; i < PROPOSAL_MAX; i++) {
1212: cprop[i] = packet_get_string(NULL);
1213: debug("got kexinit string: %s", cprop[i]);
1214: }
1215:
1216: i = (int) packet_get_char();
1217: debug("first kex follow == %d", i);
1218: i = packet_get_int();
1219: debug("reserved == %d", i);
1220:
1221: debug("done read kexinit");
1222: kex = kex_choose_conf(cprop, sprop, 1);
1223:
1224: /* KEXDH */
1225:
1226: debug("Wait SSH2_MSG_KEXDH_INIT.");
1227: packet_read_expect(&payload_len, SSH2_MSG_KEXDH_INIT);
1228:
1229: /* key, cert */
1230: dh_client_pub = BN_new();
1231: if (dh_client_pub == NULL)
1232: fatal("dh_client_pub == NULL");
1233: packet_get_bignum2(dh_client_pub, &dlen);
1234:
1235: #ifdef DEBUG_KEXDH
1236: fprintf(stderr, "\ndh_client_pub= ");
1237: bignum_print(dh_client_pub);
1238: fprintf(stderr, "\n");
1239: debug("bits %d", BN_num_bits(dh_client_pub));
1240: #endif
1241:
1242: /* generate DH key */
1.101 markus 1243: dh = dh_new_group1(); /* XXX depends on 'kex' */
1.98 markus 1244:
1245: #ifdef DEBUG_KEXDH
1246: fprintf(stderr, "\np= ");
1247: bignum_print(dh->p);
1248: fprintf(stderr, "\ng= ");
1249: bignum_print(dh->g);
1250: fprintf(stderr, "\npub= ");
1251: bignum_print(dh->pub_key);
1252: fprintf(stderr, "\n");
1253: #endif
1.101 markus 1254: if (!dh_pub_is_valid(dh, dh_client_pub))
1255: packet_disconnect("bad client public DH value");
1.98 markus 1256:
1257: klen = DH_size(dh);
1258: kbuf = xmalloc(klen);
1259: kout = DH_compute_key(kbuf, dh_client_pub, dh);
1260:
1261: #ifdef DEBUG_KEXDH
1262: debug("shared secret: len %d/%d", klen, kout);
1263: fprintf(stderr, "shared secret == ");
1264: for (i = 0; i< kout; i++)
1265: fprintf(stderr, "%02x", (kbuf[i])&0xff);
1266: fprintf(stderr, "\n");
1267: #endif
1268: shared_secret = BN_new();
1269:
1270: BN_bin2bn(kbuf, kout, shared_secret);
1271: memset(kbuf, 0, klen);
1272: xfree(kbuf);
1273:
1.111 markus 1274: /* XXX precompute? */
1.108 markus 1275: dsa_make_key_blob(sensitive_data.dsa_host_key, &server_host_key_blob, &sbloblen);
1.98 markus 1276:
1277: /* calc H */ /* XXX depends on 'kex' */
1278: hash = kex_hash(
1279: client_version_string,
1280: server_version_string,
1281: buffer_ptr(client_kexinit), buffer_len(client_kexinit),
1282: buffer_ptr(server_kexinit), buffer_len(server_kexinit),
1283: (char *)server_host_key_blob, sbloblen,
1284: dh_client_pub,
1285: dh->pub_key,
1286: shared_secret
1287: );
1288: buffer_free(client_kexinit);
1289: buffer_free(server_kexinit);
1290: xfree(client_kexinit);
1291: xfree(server_kexinit);
1292: #ifdef DEBUG_KEXDH
1.105 markus 1293: fprintf(stderr, "hash == ");
1294: for (i = 0; i< 20; i++)
1295: fprintf(stderr, "%02x", (hash[i])&0xff);
1296: fprintf(stderr, "\n");
1.98 markus 1297: #endif
1.108 markus 1298: /* save session id := H */
1299: /* XXX hashlen depends on KEX */
1300: session_id2_len = 20;
1301: session_id2 = xmalloc(session_id2_len);
1302: memcpy(session_id2, hash, session_id2_len);
1303:
1.98 markus 1304: /* sign H */
1.108 markus 1305: /* XXX hashlen depends on KEX */
1306: dsa_sign(sensitive_data.dsa_host_key, &signature, &slen, hash, 20);
1307:
1308: destroy_sensitive_data();
1.98 markus 1309:
1310: /* send server hostkey, DH pubkey 'f' and singed H */
1311: packet_start(SSH2_MSG_KEXDH_REPLY);
1312: packet_put_string((char *)server_host_key_blob, sbloblen);
1.114 ! markus 1313: packet_put_bignum2(dh->pub_key); /* f */
1.98 markus 1314: packet_put_string((char *)signature, slen);
1315: packet_send();
1.106 markus 1316: xfree(signature);
1.111 markus 1317: xfree(server_host_key_blob);
1.98 markus 1318: packet_write_wait();
1319:
1320: kex_derive_keys(kex, hash, shared_secret);
1321: packet_set_kex(kex);
1322:
1323: /* have keys, free DH */
1324: DH_free(dh);
1325:
1326: debug("send SSH2_MSG_NEWKEYS.");
1327: packet_start(SSH2_MSG_NEWKEYS);
1328: packet_send();
1329: packet_write_wait();
1330: debug("done: send SSH2_MSG_NEWKEYS.");
1331:
1332: debug("Wait SSH2_MSG_NEWKEYS.");
1333: packet_read_expect(&payload_len, SSH2_MSG_NEWKEYS);
1334: debug("GOT SSH2_MSG_NEWKEYS.");
1335:
1.100 markus 1336: #ifdef DEBUG_KEXDH
1.98 markus 1337: /* send 1st encrypted/maced/compressed message */
1338: packet_start(SSH2_MSG_IGNORE);
1339: packet_put_cstring("markus");
1340: packet_send();
1341: packet_write_wait();
1.100 markus 1342: #endif
1.98 markus 1343: debug("done: KEX2.");
1.1 deraadt 1344: }
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