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1 /*
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  * Ssh client program.  This program can be used to log into a remote machine.
6  * The software supports strong authentication, encryption, and forwarding
7  * of X11, TCP/IP, and authentication connections.
8  *
9  * As far as I am concerned, the code I have written for this software
10  * can be used freely for any purpose.  Any derived versions of this
11  * software must be clearly marked as such, and if the derived work is
12  * incompatible with the protocol description in the RFC file, it must be
13  * called by a name other than "ssh" or "Secure Shell".
14  *
15  * Copyright (c) 1999 Niels Provos.  All rights reserved.
16  * Copyright (c) 2000, 2001, 2002, 2003 Markus Friedl.  All rights reserved.
17  *
18  * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
19  * in Canada (German citizen).
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.
40  */
41
42 #include "includes.h"
43 RCSID("$OpenBSD: ssh.c,v 1.206 2003/12/16 15:49:51 markus Exp $");
44
45 #include <openssl/evp.h>
46 #include <openssl/err.h>
47
48 #include "ssh.h"
49 #include "ssh1.h"
50 #include "ssh2.h"
51 #include "compat.h"
52 #include "cipher.h"
53 #include "xmalloc.h"
54 #include "packet.h"
55 #include "buffer.h"
56 #include "channels.h"
57 #include "key.h"
58 #include "authfd.h"
59 #include "authfile.h"
60 #include "pathnames.h"
61 #include "clientloop.h"
62 #include "log.h"
63 #include "readconf.h"
64 #include "sshconnect.h"
65 #include "tildexpand.h"
66 #include "dispatch.h"
67 #include "misc.h"
68 #include "kex.h"
69 #include "mac.h"
70 #include "sshtty.h"
71
72 #ifdef SMARTCARD
73 #include "scard.h"
74 #endif
75
76 #ifdef HAVE___PROGNAME
77 extern char *__progname;
78 #else
79 char *__progname;
80 #endif
81
82 /* Flag indicating whether debug mode is on.  This can be set on the command line. */
83 int debug_flag = 0;
84
85 /* Flag indicating whether a tty should be allocated */
86 int tty_flag = 0;
87 int no_tty_flag = 0;
88 int force_tty_flag = 0;
89
90 /* don't exec a shell */
91 int no_shell_flag = 0;
92
93 /*
94  * Flag indicating that nothing should be read from stdin.  This can be set
95  * on the command line.
96  */
97 int stdin_null_flag = 0;
98
99 /*
100  * Flag indicating that ssh should fork after authentication.  This is useful
101  * so that the passphrase can be entered manually, and then ssh goes to the
102  * background.
103  */
104 int fork_after_authentication_flag = 0;
105
106 /*
107  * General data structure for command line options and options configurable
108  * in configuration files.  See readconf.h.
109  */
110 Options options;
111
112 /* optional user configfile */
113 char *config = NULL;
114
115 /*
116  * Name of the host we are connecting to.  This is the name given on the
117  * command line, or the HostName specified for the user-supplied name in a
118  * configuration file.
119  */
120 char *host;
121
122 /* socket address the host resolves to */
123 struct sockaddr_storage hostaddr;
124
125 /* Private host keys. */
126 Sensitive sensitive_data;
127
128 /* Original real UID. */
129 uid_t original_real_uid;
130 uid_t original_effective_uid;
131
132 /* command to be executed */
133 Buffer command;
134
135 /* Should we execute a command or invoke a subsystem? */
136 int subsystem_flag = 0;
137
138 /* # of replies received for global requests */
139 static int client_global_request_id = 0;
140
141 /* pid of proxycommand child process */
142 pid_t proxy_command_pid = 0;
143
144 /* Prints a help message to the user.  This function never returns. */
145
146 static void
147 usage(void)
148 {
149         fprintf(stderr, "Usage: %s [options] host [command]\n", __progname);
150         fprintf(stderr, "Options:\n");
151         fprintf(stderr, "  -l user     Log in using this user name.\n");
152         fprintf(stderr, "  -n          Redirect input from " _PATH_DEVNULL ".\n");
153         fprintf(stderr, "  -F config   Config file (default: ~/%s).\n",
154              _PATH_SSH_USER_CONFFILE);
155         fprintf(stderr, "  -A          Enable authentication agent forwarding.\n");
156         fprintf(stderr, "  -a          Disable authentication agent forwarding (default).\n");
157         fprintf(stderr, "  -X          Enable X11 connection forwarding.\n");
158         fprintf(stderr, "  -Y          Enable trusted X11 connection forwarding.\n");
159         fprintf(stderr, "  -x          Disable X11 connection forwarding (default).\n");
160         fprintf(stderr, "  -i file     Identity for public key authentication "
161             "(default: ~/.ssh/identity)\n");
162 #ifdef SMARTCARD
163         fprintf(stderr, "  -I reader   Set smartcard reader.\n");
164 #endif
165         fprintf(stderr, "  -t          Tty; allocate a tty even if command is given.\n");
166         fprintf(stderr, "  -T          Do not allocate a tty.\n");
167         fprintf(stderr, "  -v          Verbose; display verbose debugging messages.\n");
168         fprintf(stderr, "              Multiple -v increases verbosity.\n");
169         fprintf(stderr, "  -V          Display version number only.\n");
170         fprintf(stderr, "  -q          Quiet; don't display any warning messages.\n");
171         fprintf(stderr, "  -f          Fork into background after authentication.\n");
172         fprintf(stderr, "  -e char     Set escape character; ``none'' = disable (default: ~).\n");
173
174         fprintf(stderr, "  -c cipher   Select encryption algorithm\n");
175         fprintf(stderr, "  -m macs     Specify MAC algorithms for protocol version 2.\n");
176         fprintf(stderr, "  -p port     Connect to this port.  Server must be on the same port.\n");
177         fprintf(stderr, "  -L listen-port:host:port   Forward local port to remote address\n");
178         fprintf(stderr, "  -R listen-port:host:port   Forward remote port to local address\n");
179         fprintf(stderr, "              These cause %s to listen for connections on a port, and\n", __progname);
180         fprintf(stderr, "              forward them to the other side by connecting to host:port.\n");
181         fprintf(stderr, "  -D port     Enable dynamic application-level port forwarding.\n");
182         fprintf(stderr, "  -C          Enable compression.\n");
183         fprintf(stderr, "  -N          Do not execute a shell or command.\n");
184         fprintf(stderr, "  -g          Allow remote hosts to connect to forwarded ports.\n");
185         fprintf(stderr, "  -1          Force protocol version 1.\n");
186         fprintf(stderr, "  -2          Force protocol version 2.\n");
187         fprintf(stderr, "  -4          Use IPv4 only.\n");
188         fprintf(stderr, "  -6          Use IPv6 only.\n");
189         fprintf(stderr, "  -o 'option' Process the option as if it was read from a configuration file.\n");
190         fprintf(stderr, "  -s          Invoke command (mandatory) as SSH2 subsystem.\n");
191         fprintf(stderr, "  -b addr     Local IP address.\n");
192         exit(1);
193 }
194
195 static int ssh_session(void);
196 static int ssh_session2(void);
197 static void load_public_identity_files(void);
198
199 /*
200  * Main program for the ssh client.
201  */
202 int
203 main(int ac, char **av)
204 {
205         int i, opt, exit_status;
206         u_short fwd_port, fwd_host_port;
207         char sfwd_port[6], sfwd_host_port[6];
208         char *p, *cp, *line, buf[256];
209         struct stat st;
210         struct passwd *pw;
211         int dummy;
212         extern int optind, optreset;
213         extern char *optarg;
214
215         __progname = ssh_get_progname(av[0]);
216         init_rng();
217
218         /*
219          * Save the original real uid.  It will be needed later (uid-swapping
220          * may clobber the real uid).
221          */
222         original_real_uid = getuid();
223         original_effective_uid = geteuid();
224
225         /*
226          * Use uid-swapping to give up root privileges for the duration of
227          * option processing.  We will re-instantiate the rights when we are
228          * ready to create the privileged port, and will permanently drop
229          * them when the port has been created (actually, when the connection
230          * has been made, as we may need to create the port several times).
231          */
232         PRIV_END;
233
234 #ifdef HAVE_SETRLIMIT
235         /* If we are installed setuid root be careful to not drop core. */
236         if (original_real_uid != original_effective_uid) {
237                 struct rlimit rlim;
238                 rlim.rlim_cur = rlim.rlim_max = 0;
239                 if (setrlimit(RLIMIT_CORE, &rlim) < 0)
240                         fatal("setrlimit failed: %.100s", strerror(errno));
241         }
242 #endif
243         /* Get user data. */
244         pw = getpwuid(original_real_uid);
245         if (!pw) {
246                 logit("You don't exist, go away!");
247                 exit(1);
248         }
249         /* Take a copy of the returned structure. */
250         pw = pwcopy(pw);
251
252         /*
253          * Set our umask to something reasonable, as some files are created
254          * with the default umask.  This will make them world-readable but
255          * writable only by the owner, which is ok for all files for which we
256          * don't set the modes explicitly.
257          */
258         umask(022);
259
260         /* Initialize option structure to indicate that no values have been set. */
261         initialize_options(&options);
262
263         /* Parse command-line arguments. */
264         host = NULL;
265
266 again:
267         while ((opt = getopt(ac, av,
268             "1246ab:c:e:fgi:kl:m:no:p:qstvxACD:F:I:L:NPR:TVXY")) != -1) {
269                 switch (opt) {
270                 case '1':
271                         options.protocol = SSH_PROTO_1;
272                         break;
273                 case '2':
274                         options.protocol = SSH_PROTO_2;
275                         break;
276                 case '4':
277                         options.address_family = AF_INET;
278                         break;
279                 case '6':
280                         options.address_family = AF_INET6;
281                         break;
282                 case 'n':
283                         stdin_null_flag = 1;
284                         break;
285                 case 'f':
286                         fork_after_authentication_flag = 1;
287                         stdin_null_flag = 1;
288                         break;
289                 case 'x':
290                         options.forward_x11 = 0;
291                         break;
292                 case 'X':
293                         options.forward_x11 = 1;
294                         break;
295                 case 'Y':
296                         options.forward_x11 = 1;
297                         options.forward_x11_trusted = 1;
298                         break;
299                 case 'g':
300                         options.gateway_ports = 1;
301                         break;
302                 case 'P':       /* deprecated */
303                         options.use_privileged_port = 0;
304                         break;
305                 case 'a':
306                         options.forward_agent = 0;
307                         break;
308                 case 'A':
309                         options.forward_agent = 1;
310                         break;
311                 case 'k':
312                         options.gss_deleg_creds = 0;
313                         break;
314                 case 'i':
315                         if (stat(optarg, &st) < 0) {
316                                 fprintf(stderr, "Warning: Identity file %s "
317                                     "does not exist.\n", optarg);
318                                 break;
319                         }
320                         if (options.num_identity_files >=
321                             SSH_MAX_IDENTITY_FILES)
322                                 fatal("Too many identity files specified "
323                                     "(max %d)", SSH_MAX_IDENTITY_FILES);
324                         options.identity_files[options.num_identity_files++] =
325                             xstrdup(optarg);
326                         break;
327                 case 'I':
328 #ifdef SMARTCARD
329                         options.smartcard_device = xstrdup(optarg);
330 #else
331                         fprintf(stderr, "no support for smartcards.\n");
332 #endif
333                         break;
334                 case 't':
335                         if (tty_flag)
336                                 force_tty_flag = 1;
337                         tty_flag = 1;
338                         break;
339                 case 'v':
340                         if (debug_flag == 0) {
341                                 debug_flag = 1;
342                                 options.log_level = SYSLOG_LEVEL_DEBUG1;
343                         } else {
344                                 if (options.log_level < SYSLOG_LEVEL_DEBUG3)
345                                         options.log_level++;
346                                 break;
347                         }
348                         /* fallthrough */
349                 case 'V':
350                         fprintf(stderr,
351                             "%s, SSH protocols %d.%d/%d.%d, %s\n",
352                             SSH_VERSION,
353                             PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
354                             PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
355                             SSLeay_version(SSLEAY_VERSION));
356                         if (opt == 'V')
357                                 exit(0);
358                         break;
359                 case 'q':
360                         options.log_level = SYSLOG_LEVEL_QUIET;
361                         break;
362                 case 'e':
363                         if (optarg[0] == '^' && optarg[2] == 0 &&
364                             (u_char) optarg[1] >= 64 &&
365                             (u_char) optarg[1] < 128)
366                                 options.escape_char = (u_char) optarg[1] & 31;
367                         else if (strlen(optarg) == 1)
368                                 options.escape_char = (u_char) optarg[0];
369                         else if (strcmp(optarg, "none") == 0)
370                                 options.escape_char = SSH_ESCAPECHAR_NONE;
371                         else {
372                                 fprintf(stderr, "Bad escape character '%s'.\n",
373                                     optarg);
374                                 exit(1);
375                         }
376                         break;
377                 case 'c':
378                         if (ciphers_valid(optarg)) {
379                                 /* SSH2 only */
380                                 options.ciphers = xstrdup(optarg);
381                                 options.cipher = SSH_CIPHER_ILLEGAL;
382                         } else {
383                                 /* SSH1 only */
384                                 options.cipher = cipher_number(optarg);
385                                 if (options.cipher == -1) {
386                                         fprintf(stderr,
387                                             "Unknown cipher type '%s'\n",
388                                             optarg);
389                                         exit(1);
390                                 }
391                                 if (options.cipher == SSH_CIPHER_3DES)
392                                         options.ciphers = "3des-cbc";
393                                 else if (options.cipher == SSH_CIPHER_BLOWFISH)
394                                         options.ciphers = "blowfish-cbc";
395                                 else
396                                         options.ciphers = (char *)-1;
397                         }
398                         break;
399                 case 'm':
400                         if (mac_valid(optarg))
401                                 options.macs = xstrdup(optarg);
402                         else {
403                                 fprintf(stderr, "Unknown mac type '%s'\n",
404                                     optarg);
405                                 exit(1);
406                         }
407                         break;
408                 case 'p':
409                         options.port = a2port(optarg);
410                         if (options.port == 0) {
411                                 fprintf(stderr, "Bad port '%s'\n", optarg);
412                                 exit(1);
413                         }
414                         break;
415                 case 'l':
416                         options.user = optarg;
417                         break;
418
419                 case 'L':
420                 case 'R':
421                         if (sscanf(optarg, "%5[0123456789]:%255[^:]:%5[0123456789]",
422                             sfwd_port, buf, sfwd_host_port) != 3 &&
423                             sscanf(optarg, "%5[0123456789]/%255[^/]/%5[0123456789]",
424                             sfwd_port, buf, sfwd_host_port) != 3) {
425                                 fprintf(stderr,
426                                     "Bad forwarding specification '%s'\n",
427                                     optarg);
428                                 usage();
429                                 /* NOTREACHED */
430                         }
431                         if ((fwd_port = a2port(sfwd_port)) == 0 ||
432                             (fwd_host_port = a2port(sfwd_host_port)) == 0) {
433                                 fprintf(stderr,
434                                     "Bad forwarding port(s) '%s'\n", optarg);
435                                 exit(1);
436                         }
437                         if (opt == 'L')
438                                 add_local_forward(&options, fwd_port, buf,
439                                     fwd_host_port);
440                         else if (opt == 'R')
441                                 add_remote_forward(&options, fwd_port, buf,
442                                     fwd_host_port);
443                         break;
444
445                 case 'D':
446                         fwd_port = a2port(optarg);
447                         if (fwd_port == 0) {
448                                 fprintf(stderr, "Bad dynamic port '%s'\n",
449                                     optarg);
450                                 exit(1);
451                         }
452                         add_local_forward(&options, fwd_port, "socks", 0);
453                         break;
454
455                 case 'C':
456                         options.compression = 1;
457                         break;
458                 case 'N':
459                         no_shell_flag = 1;
460                         no_tty_flag = 1;
461                         break;
462                 case 'T':
463                         no_tty_flag = 1;
464                         break;
465                 case 'o':
466                         dummy = 1;
467                         line = xstrdup(optarg);
468                         if (process_config_line(&options, host ? host : "",
469                             line, "command-line", 0, &dummy) != 0)
470                                 exit(1);
471                         xfree(line);
472                         break;
473                 case 's':
474                         subsystem_flag = 1;
475                         break;
476                 case 'b':
477                         options.bind_address = optarg;
478                         break;
479                 case 'F':
480                         config = optarg;
481                         break;
482                 default:
483                         usage();
484                 }
485         }
486
487         ac -= optind;
488         av += optind;
489
490         if (ac > 0 && !host && **av != '-') {
491                 if (strrchr(*av, '@')) {
492                         p = xstrdup(*av);
493                         cp = strrchr(p, '@');
494                         if (cp == NULL || cp == p)
495                                 usage();
496                         options.user = p;
497                         *cp = '\0';
498                         host = ++cp;
499                 } else
500                         host = *av;
501                 if (ac > 1) {
502                         optind = optreset = 1;
503                         goto again;
504                 }
505                 ac--, av++;
506         }
507
508         /* Check that we got a host name. */
509         if (!host)
510                 usage();
511
512         SSLeay_add_all_algorithms();
513         ERR_load_crypto_strings();
514
515         /* Initialize the command to execute on remote host. */
516         buffer_init(&command);
517
518         /*
519          * Save the command to execute on the remote host in a buffer. There
520          * is no limit on the length of the command, except by the maximum
521          * packet size.  Also sets the tty flag if there is no command.
522          */
523         if (!ac) {
524                 /* No command specified - execute shell on a tty. */
525                 tty_flag = 1;
526                 if (subsystem_flag) {
527                         fprintf(stderr,
528                             "You must specify a subsystem to invoke.\n");
529                         usage();
530                 }
531         } else {
532                 /* A command has been specified.  Store it into the buffer. */
533                 for (i = 0; i < ac; i++) {
534                         if (i)
535                                 buffer_append(&command, " ", 1);
536                         buffer_append(&command, av[i], strlen(av[i]));
537                 }
538         }
539
540         /* Cannot fork to background if no command. */
541         if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
542                 fatal("Cannot fork into background without a command to execute.");
543
544         /* Allocate a tty by default if no command specified. */
545         if (buffer_len(&command) == 0)
546                 tty_flag = 1;
547
548         /* Force no tty */
549         if (no_tty_flag)
550                 tty_flag = 0;
551         /* Do not allocate a tty if stdin is not a tty. */
552         if (!isatty(fileno(stdin)) && !force_tty_flag) {
553                 if (tty_flag)
554                         logit("Pseudo-terminal will not be allocated because stdin is not a terminal.");
555                 tty_flag = 0;
556         }
557
558         /*
559          * Initialize "log" output.  Since we are the client all output
560          * actually goes to stderr.
561          */
562         log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
563             SYSLOG_FACILITY_USER, 1);
564
565         /*
566          * Read per-user configuration file.  Ignore the system wide config
567          * file if the user specifies a config file on the command line.
568          */
569         if (config != NULL) {
570                 if (!read_config_file(config, host, &options))
571                         fatal("Can't open user config file %.100s: "
572                             "%.100s", config, strerror(errno));
573         } else  {
574             /*
575              * Since the config file parsing code aborts if it sees
576              * options it doesn't recognize, allow users to put
577              * options specific to compile-time add-ons in alternate
578              * config files so their primary config file will
579              * interoperate SSH versions that don't support those
580              * options.
581              */
582 #ifdef GSSAPI
583                 snprintf(buf, sizeof buf, "%.100s/%.100s.gssapi", pw->pw_dir,
584                     _PATH_SSH_USER_CONFFILE);
585                 (void)read_config_file(buf, host, &options);
586 #ifdef GSI
587                 snprintf(buf, sizeof buf, "%.100s/%.100s.gsi", pw->pw_dir,
588                     _PATH_SSH_USER_CONFFILE);
589                 (void)read_config_file(buf, host, &options);
590 #endif
591 #if defined(KRB5)
592                 snprintf(buf, sizeof buf, "%.100s/%.100s.krb", pw->pw_dir,
593                     _PATH_SSH_USER_CONFFILE);
594                 (void)read_config_file(buf, host, &options);
595 #endif
596 #endif
597                 snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir,
598                     _PATH_SSH_USER_CONFFILE);
599                 (void)read_config_file(buf, host, &options);
600
601                 /* Read systemwide configuration file after use config. */
602                 (void)read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
603         }
604
605         /* Fill configuration defaults. */
606         fill_default_options(&options);
607
608         channel_set_af(options.address_family);
609
610         /* reinit */
611         log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
612
613         seed_rng();
614
615         if (options.user == NULL) {
616                 options.user = xstrdup(pw->pw_name);
617                 options.implicit = 1;
618         }
619         else options.implicit = 0;
620
621         if (options.hostname != NULL)
622                 host = options.hostname;
623
624         /* force lowercase for hostkey matching */
625         if (options.host_key_alias != NULL) {
626                 for (p = options.host_key_alias; *p; p++)
627                         if (isupper(*p))
628                                 *p = tolower(*p);
629         }
630
631         if (options.proxy_command != NULL &&
632             strcmp(options.proxy_command, "none") == 0)
633                 options.proxy_command = NULL;
634
635         /* Open a connection to the remote host. */
636         if (ssh_connect(host, &hostaddr, options.port,
637             options.address_family, options.connection_attempts,
638 #ifdef HAVE_CYGWIN
639             options.use_privileged_port,
640 #else
641             original_effective_uid == 0 && options.use_privileged_port,
642 #endif
643             options.proxy_command) != 0)
644                 exit(1);
645
646         /*
647          * If we successfully made the connection, load the host private key
648          * in case we will need it later for combined rsa-rhosts
649          * authentication. This must be done before releasing extra
650          * privileges, because the file is only readable by root.
651          * If we cannot access the private keys, load the public keys
652          * instead and try to execute the ssh-keysign helper instead.
653          */
654         sensitive_data.nkeys = 0;
655         sensitive_data.keys = NULL;
656         sensitive_data.external_keysign = 0;
657         if (options.rhosts_rsa_authentication ||
658             options.hostbased_authentication) {
659                 sensitive_data.nkeys = 3;
660                 sensitive_data.keys = xmalloc(sensitive_data.nkeys *
661                     sizeof(Key));
662
663                 PRIV_START;
664                 sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
665                     _PATH_HOST_KEY_FILE, "", NULL);
666                 sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
667                     _PATH_HOST_DSA_KEY_FILE, "", NULL);
668                 sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
669                     _PATH_HOST_RSA_KEY_FILE, "", NULL);
670                 PRIV_END;
671
672                 if (options.hostbased_authentication == 1 &&
673                     sensitive_data.keys[0] == NULL &&
674                     sensitive_data.keys[1] == NULL &&
675                     sensitive_data.keys[2] == NULL) {
676                         sensitive_data.keys[1] = key_load_public(
677                             _PATH_HOST_DSA_KEY_FILE, NULL);
678                         sensitive_data.keys[2] = key_load_public(
679                             _PATH_HOST_RSA_KEY_FILE, NULL);
680                         sensitive_data.external_keysign = 1;
681                 }
682         }
683         /*
684          * Get rid of any extra privileges that we may have.  We will no
685          * longer need them.  Also, extra privileges could make it very hard
686          * to read identity files and other non-world-readable files from the
687          * user's home directory if it happens to be on a NFS volume where
688          * root is mapped to nobody.
689          */
690         seteuid(original_real_uid);
691         setuid(original_real_uid);
692
693         /*
694          * Now that we are back to our own permissions, create ~/.ssh
695          * directory if it doesn\'t already exist.
696          */
697         snprintf(buf, sizeof buf, "%.100s%s%.100s", pw->pw_dir, strcmp(pw->pw_dir, "/") ? "/" : "", _PATH_SSH_USER_DIR);
698         if (stat(buf, &st) < 0)
699                 if (mkdir(buf, 0700) < 0)
700                         error("Could not create directory '%.200s'.", buf);
701
702         /* load options.identity_files */
703         load_public_identity_files();
704
705         /* Expand ~ in known host file names. */
706         /* XXX mem-leaks: */
707         options.system_hostfile =
708             tilde_expand_filename(options.system_hostfile, original_real_uid);
709         options.user_hostfile =
710             tilde_expand_filename(options.user_hostfile, original_real_uid);
711         options.system_hostfile2 =
712             tilde_expand_filename(options.system_hostfile2, original_real_uid);
713         options.user_hostfile2 =
714             tilde_expand_filename(options.user_hostfile2, original_real_uid);
715
716         signal(SIGPIPE, SIG_IGN); /* ignore SIGPIPE early */
717
718         /* Log into the remote system.  This never returns if the login fails. */
719         ssh_login(&sensitive_data, host, (struct sockaddr *)&hostaddr, pw);
720
721         /* We no longer need the private host keys.  Clear them now. */
722         if (sensitive_data.nkeys != 0) {
723                 for (i = 0; i < sensitive_data.nkeys; i++) {
724                         if (sensitive_data.keys[i] != NULL) {
725                                 /* Destroys contents safely */
726                                 debug3("clear hostkey %d", i);
727                                 key_free(sensitive_data.keys[i]);
728                                 sensitive_data.keys[i] = NULL;
729                         }
730                 }
731                 xfree(sensitive_data.keys);
732         }
733         for (i = 0; i < options.num_identity_files; i++) {
734                 if (options.identity_files[i]) {
735                         xfree(options.identity_files[i]);
736                         options.identity_files[i] = NULL;
737                 }
738                 if (options.identity_keys[i]) {
739                         key_free(options.identity_keys[i]);
740                         options.identity_keys[i] = NULL;
741                 }
742         }
743
744         exit_status = compat20 ? ssh_session2() : ssh_session();
745         packet_close();
746
747         /*
748          * Send SIGHUP to proxy command if used. We don't wait() in
749          * case it hangs and instead rely on init to reap the child
750          */
751         if (proxy_command_pid > 1)
752                 kill(proxy_command_pid, SIGHUP);
753
754         return exit_status;
755 }
756
757 #define SSH_X11_PROTO "MIT-MAGIC-COOKIE-1"
758
759 static void
760 x11_get_proto(char **_proto, char **_data)
761 {
762         char cmd[1024];
763         char line[512];
764         char xdisplay[512];
765         static char proto[512], data[512];
766         FILE *f;
767         int got_data = 0, generated = 0, do_unlink = 0, i;
768         char *display, *xauthdir, *xauthfile;
769         struct stat st;
770
771         xauthdir = xauthfile = NULL;
772         *_proto = proto;
773         *_data = data;
774         proto[0] = data[0] = '\0';
775
776         if (!options.xauth_location ||
777             (stat(options.xauth_location, &st) == -1)) {
778                 debug("No xauth program.");
779         } else {
780                 if ((display = getenv("DISPLAY")) == NULL) {
781                         debug("x11_get_proto: DISPLAY not set");
782                         return;
783                 }
784                 /*
785                  * Handle FamilyLocal case where $DISPLAY does
786                  * not match an authorization entry.  For this we
787                  * just try "xauth list unix:displaynum.screennum".
788                  * XXX: "localhost" match to determine FamilyLocal
789                  *      is not perfect.
790                  */
791                 if (strncmp(display, "localhost:", 10) == 0) {
792                         snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
793                             display + 10);
794                         display = xdisplay;
795                 }
796                 if (options.forward_x11_trusted == 0) {
797                         xauthdir = xmalloc(MAXPATHLEN);
798                         xauthfile = xmalloc(MAXPATHLEN);
799                         strlcpy(xauthdir, "/tmp/ssh-XXXXXXXXXX", MAXPATHLEN);
800                         if (mkdtemp(xauthdir) != NULL) {
801                                 do_unlink = 1;
802                                 snprintf(xauthfile, MAXPATHLEN, "%s/xauthfile",
803                                     xauthdir);
804                                 snprintf(cmd, sizeof(cmd),
805                                     "%s -f %s generate %s " SSH_X11_PROTO
806                                     " untrusted timeout 120 2>" _PATH_DEVNULL,
807                                     options.xauth_location, xauthfile, display);
808                                 debug2("x11_get_proto: %s", cmd);
809                                 if (system(cmd) == 0)
810                                         generated = 1;
811                         }
812                 }
813                 snprintf(cmd, sizeof(cmd),
814                     "%s %s%s list %s . 2>" _PATH_DEVNULL,
815                     options.xauth_location,
816                     generated ? "-f " : "" ,
817                     generated ? xauthfile : "",
818                     display);
819                 debug2("x11_get_proto: %s", cmd);
820                 f = popen(cmd, "r");
821                 if (f && fgets(line, sizeof(line), f) &&
822                     sscanf(line, "%*s %511s %511s", proto, data) == 2)
823                         got_data = 1;
824                 if (f)
825                         pclose(f);
826         }
827
828         if (do_unlink) {
829                 unlink(xauthfile);
830                 rmdir(xauthdir);
831         }
832         if (xauthdir)
833                 xfree(xauthdir);
834         if (xauthfile)
835                 xfree(xauthfile);
836
837         /*
838          * If we didn't get authentication data, just make up some
839          * data.  The forwarding code will check the validity of the
840          * response anyway, and substitute this data.  The X11
841          * server, however, will ignore this fake data and use
842          * whatever authentication mechanisms it was using otherwise
843          * for the local connection.
844          */
845         if (!got_data) {
846                 u_int32_t rand = 0;
847
848                 logit("Warning: No xauth data; "
849                     "using fake authentication data for X11 forwarding.");
850                 strlcpy(proto, SSH_X11_PROTO, sizeof proto);
851                 for (i = 0; i < 16; i++) {
852                         if (i % 4 == 0)
853                                 rand = arc4random();
854                         snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
855                             rand & 0xff);
856                         rand >>= 8;
857                 }
858         }
859 }
860
861 static void
862 ssh_init_forwarding(void)
863 {
864         int success = 0;
865         int i;
866
867         /* Initiate local TCP/IP port forwardings. */
868         for (i = 0; i < options.num_local_forwards; i++) {
869                 debug("Connections to local port %d forwarded to remote address %.200s:%d",
870                     options.local_forwards[i].port,
871                     options.local_forwards[i].host,
872                     options.local_forwards[i].host_port);
873                 success += channel_setup_local_fwd_listener(
874                     options.local_forwards[i].port,
875                     options.local_forwards[i].host,
876                     options.local_forwards[i].host_port,
877                     options.gateway_ports);
878         }
879         if (i > 0 && success == 0)
880                 error("Could not request local forwarding.");
881
882         /* Initiate remote TCP/IP port forwardings. */
883         for (i = 0; i < options.num_remote_forwards; i++) {
884                 debug("Connections to remote port %d forwarded to local address %.200s:%d",
885                     options.remote_forwards[i].port,
886                     options.remote_forwards[i].host,
887                     options.remote_forwards[i].host_port);
888                 channel_request_remote_forwarding(
889                     options.remote_forwards[i].port,
890                     options.remote_forwards[i].host,
891                     options.remote_forwards[i].host_port);
892         }
893 }
894
895 static void
896 check_agent_present(void)
897 {
898         if (options.forward_agent) {
899                 /* Clear agent forwarding if we don\'t have an agent. */
900                 if (!ssh_agent_present())
901                         options.forward_agent = 0;
902         }
903 }
904
905 static int
906 ssh_session(void)
907 {
908         int type;
909         int interactive = 0;
910         int have_tty = 0;
911         struct winsize ws;
912         char *cp;
913
914         /* Enable compression if requested. */
915         if (options.compression) {
916                 debug("Requesting compression at level %d.", options.compression_level);
917
918                 if (options.compression_level < 1 || options.compression_level > 9)
919                         fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
920
921                 /* Send the request. */
922                 packet_start(SSH_CMSG_REQUEST_COMPRESSION);
923                 packet_put_int(options.compression_level);
924                 packet_send();
925                 packet_write_wait();
926                 type = packet_read();
927                 if (type == SSH_SMSG_SUCCESS)
928                         packet_start_compression(options.compression_level);
929                 else if (type == SSH_SMSG_FAILURE)
930                         logit("Warning: Remote host refused compression.");
931                 else
932                         packet_disconnect("Protocol error waiting for compression response.");
933         }
934         /* Allocate a pseudo tty if appropriate. */
935         if (tty_flag) {
936                 debug("Requesting pty.");
937
938                 /* Start the packet. */
939                 packet_start(SSH_CMSG_REQUEST_PTY);
940
941                 /* Store TERM in the packet.  There is no limit on the
942                    length of the string. */
943                 cp = getenv("TERM");
944                 if (!cp)
945                         cp = "";
946                 packet_put_cstring(cp);
947
948                 /* Store window size in the packet. */
949                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
950                         memset(&ws, 0, sizeof(ws));
951                 packet_put_int(ws.ws_row);
952                 packet_put_int(ws.ws_col);
953                 packet_put_int(ws.ws_xpixel);
954                 packet_put_int(ws.ws_ypixel);
955
956                 /* Store tty modes in the packet. */
957                 tty_make_modes(fileno(stdin), NULL);
958
959                 /* Send the packet, and wait for it to leave. */
960                 packet_send();
961                 packet_write_wait();
962
963                 /* Read response from the server. */
964                 type = packet_read();
965                 if (type == SSH_SMSG_SUCCESS) {
966                         interactive = 1;
967                         have_tty = 1;
968                 } else if (type == SSH_SMSG_FAILURE)
969                         logit("Warning: Remote host failed or refused to allocate a pseudo tty.");
970                 else
971                         packet_disconnect("Protocol error waiting for pty request response.");
972         }
973         /* Request X11 forwarding if enabled and DISPLAY is set. */
974         if (options.forward_x11 && getenv("DISPLAY") != NULL) {
975                 char *proto, *data;
976                 /* Get reasonable local authentication information. */
977                 x11_get_proto(&proto, &data);
978                 /* Request forwarding with authentication spoofing. */
979                 debug("Requesting X11 forwarding with authentication spoofing.");
980                 x11_request_forwarding_with_spoofing(0, proto, data);
981
982                 /* Read response from the server. */
983                 type = packet_read();
984                 if (type == SSH_SMSG_SUCCESS) {
985                         interactive = 1;
986                 } else if (type == SSH_SMSG_FAILURE) {
987                         logit("Warning: Remote host denied X11 forwarding.");
988                 } else {
989                         packet_disconnect("Protocol error waiting for X11 forwarding");
990                 }
991         }
992         /* Tell the packet module whether this is an interactive session. */
993         packet_set_interactive(interactive);
994
995         /* Request authentication agent forwarding if appropriate. */
996         check_agent_present();
997
998         if (options.forward_agent) {
999                 debug("Requesting authentication agent forwarding.");
1000                 auth_request_forwarding();
1001
1002                 /* Read response from the server. */
1003                 type = packet_read();
1004                 packet_check_eom();
1005                 if (type != SSH_SMSG_SUCCESS)
1006                         logit("Warning: Remote host denied authentication agent forwarding.");
1007         }
1008
1009         /* Initiate port forwardings. */
1010         ssh_init_forwarding();
1011
1012         /* If requested, let ssh continue in the background. */
1013         if (fork_after_authentication_flag)
1014                 if (daemon(1, 1) < 0)
1015                         fatal("daemon() failed: %.200s", strerror(errno));
1016
1017         /*
1018          * If a command was specified on the command line, execute the
1019          * command now. Otherwise request the server to start a shell.
1020          */
1021         if (buffer_len(&command) > 0) {
1022                 int len = buffer_len(&command);
1023                 if (len > 900)
1024                         len = 900;
1025                 debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1026                 packet_start(SSH_CMSG_EXEC_CMD);
1027                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1028                 packet_send();
1029                 packet_write_wait();
1030         } else {
1031                 debug("Requesting shell.");
1032                 packet_start(SSH_CMSG_EXEC_SHELL);
1033                 packet_send();
1034                 packet_write_wait();
1035         }
1036
1037         /* Enter the interactive session. */
1038         return client_loop(have_tty, tty_flag ?
1039             options.escape_char : SSH_ESCAPECHAR_NONE, 0);
1040 }
1041
1042 static void
1043 client_subsystem_reply(int type, u_int32_t seq, void *ctxt)
1044 {
1045         int id, len;
1046
1047         id = packet_get_int();
1048         len = buffer_len(&command);
1049         if (len > 900)
1050                 len = 900;
1051         packet_check_eom();
1052         if (type == SSH2_MSG_CHANNEL_FAILURE)
1053                 fatal("Request for subsystem '%.*s' failed on channel %d",
1054                     len, (u_char *)buffer_ptr(&command), id);
1055 }
1056
1057 void
1058 client_global_request_reply_fwd(int type, u_int32_t seq, void *ctxt)
1059 {
1060         int i;
1061
1062         i = client_global_request_id++;
1063         if (i >= options.num_remote_forwards)
1064                 return;
1065         debug("remote forward %s for: listen %d, connect %s:%d",
1066             type == SSH2_MSG_REQUEST_SUCCESS ? "success" : "failure",
1067             options.remote_forwards[i].port,
1068             options.remote_forwards[i].host,
1069             options.remote_forwards[i].host_port);
1070         if (type == SSH2_MSG_REQUEST_FAILURE)
1071                 logit("Warning: remote port forwarding failed for listen port %d",
1072                     options.remote_forwards[i].port);
1073 }
1074
1075 /* request pty/x11/agent/tcpfwd/shell for channel */
1076 static void
1077 ssh_session2_setup(int id, void *arg)
1078 {
1079         int len;
1080         int interactive = 0;
1081         struct termios tio;
1082
1083         debug2("ssh_session2_setup: id %d", id);
1084
1085         if (tty_flag) {
1086                 struct winsize ws;
1087                 char *cp;
1088                 cp = getenv("TERM");
1089                 if (!cp)
1090                         cp = "";
1091                 /* Store window size in the packet. */
1092                 if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
1093                         memset(&ws, 0, sizeof(ws));
1094
1095                 channel_request_start(id, "pty-req", 0);
1096                 packet_put_cstring(cp);
1097                 packet_put_int(ws.ws_col);
1098                 packet_put_int(ws.ws_row);
1099                 packet_put_int(ws.ws_xpixel);
1100                 packet_put_int(ws.ws_ypixel);
1101                 tio = get_saved_tio();
1102                 tty_make_modes(/*ignored*/ 0, &tio);
1103                 packet_send();
1104                 interactive = 1;
1105                 /* XXX wait for reply */
1106         }
1107         if (options.forward_x11 &&
1108             getenv("DISPLAY") != NULL) {
1109                 char *proto, *data;
1110                 /* Get reasonable local authentication information. */
1111                 x11_get_proto(&proto, &data);
1112                 /* Request forwarding with authentication spoofing. */
1113                 debug("Requesting X11 forwarding with authentication spoofing.");
1114                 x11_request_forwarding_with_spoofing(id, proto, data);
1115                 interactive = 1;
1116                 /* XXX wait for reply */
1117         }
1118
1119         check_agent_present();
1120         if (options.forward_agent) {
1121                 debug("Requesting authentication agent forwarding.");
1122                 channel_request_start(id, "auth-agent-req@openssh.com", 0);
1123                 packet_send();
1124         }
1125
1126         len = buffer_len(&command);
1127         if (len > 0) {
1128                 if (len > 900)
1129                         len = 900;
1130                 if (subsystem_flag) {
1131                         debug("Sending subsystem: %.*s", len, (u_char *)buffer_ptr(&command));
1132                         channel_request_start(id, "subsystem", /*want reply*/ 1);
1133                         /* register callback for reply */
1134                         /* XXX we assume that client_loop has already been called */
1135                         dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
1136                         dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1137                 } else {
1138                         debug("Sending command: %.*s", len, (u_char *)buffer_ptr(&command));
1139                         channel_request_start(id, "exec", 0);
1140                 }
1141                 packet_put_string(buffer_ptr(&command), buffer_len(&command));
1142                 packet_send();
1143         } else {
1144                 channel_request_start(id, "shell", 0);
1145                 packet_send();
1146         }
1147
1148         packet_set_interactive(interactive);
1149 }
1150
1151 /* open new channel for a session */
1152 static int
1153 ssh_session2_open(void)
1154 {
1155         Channel *c;
1156         int window, packetmax, in, out, err;
1157
1158         if (stdin_null_flag) {
1159                 in = open(_PATH_DEVNULL, O_RDONLY);
1160         } else {
1161                 in = dup(STDIN_FILENO);
1162         }
1163         out = dup(STDOUT_FILENO);
1164         err = dup(STDERR_FILENO);
1165
1166         if (in < 0 || out < 0 || err < 0)
1167                 fatal("dup() in/out/err failed");
1168
1169         /* enable nonblocking unless tty */
1170         if (!isatty(in))
1171                 set_nonblock(in);
1172         if (!isatty(out))
1173                 set_nonblock(out);
1174         if (!isatty(err))
1175                 set_nonblock(err);
1176
1177         window = CHAN_SES_WINDOW_DEFAULT;
1178         packetmax = CHAN_SES_PACKET_DEFAULT;
1179         if (tty_flag) {
1180                 window >>= 1;
1181                 packetmax >>= 1;
1182         }
1183         c = channel_new(
1184             "session", SSH_CHANNEL_OPENING, in, out, err,
1185             window, packetmax, CHAN_EXTENDED_WRITE,
1186             "client-session", /*nonblock*/0);
1187
1188         debug3("ssh_session2_open: channel_new: %d", c->self);
1189
1190         channel_send_open(c->self);
1191         if (!no_shell_flag)
1192                 channel_register_confirm(c->self, ssh_session2_setup);
1193
1194         return c->self;
1195 }
1196
1197 static int
1198 ssh_session2(void)
1199 {
1200         int id = -1;
1201
1202         /* XXX should be pre-session */
1203         ssh_init_forwarding();
1204
1205         if (!no_shell_flag || (datafellows & SSH_BUG_DUMMYCHAN))
1206                 id = ssh_session2_open();
1207
1208         /* If requested, let ssh continue in the background. */
1209         if (fork_after_authentication_flag)
1210                 if (daemon(1, 1) < 0)
1211                         fatal("daemon() failed: %.200s", strerror(errno));
1212
1213         return client_loop(tty_flag, tty_flag ?
1214             options.escape_char : SSH_ESCAPECHAR_NONE, id);
1215 }
1216
1217 static void
1218 load_public_identity_files(void)
1219 {
1220         char *filename;
1221         int i = 0;
1222         Key *public;
1223 #ifdef SMARTCARD
1224         Key **keys;
1225
1226         if (options.smartcard_device != NULL &&
1227             options.num_identity_files < SSH_MAX_IDENTITY_FILES &&
1228             (keys = sc_get_keys(options.smartcard_device, NULL)) != NULL ) {
1229                 int count = 0;
1230                 for (i = 0; keys[i] != NULL; i++) {
1231                         count++;
1232                         memmove(&options.identity_files[1], &options.identity_files[0],
1233                             sizeof(char *) * (SSH_MAX_IDENTITY_FILES - 1));
1234                         memmove(&options.identity_keys[1], &options.identity_keys[0],
1235                             sizeof(Key *) * (SSH_MAX_IDENTITY_FILES - 1));
1236                         options.num_identity_files++;
1237                         options.identity_keys[0] = keys[i];
1238                         options.identity_files[0] = sc_get_key_label(keys[i]);
1239                 }
1240                 if (options.num_identity_files > SSH_MAX_IDENTITY_FILES)
1241                         options.num_identity_files = SSH_MAX_IDENTITY_FILES;
1242                 i = count;
1243                 xfree(keys);
1244         }
1245 #endif /* SMARTCARD */
1246         for (; i < options.num_identity_files; i++) {
1247                 filename = tilde_expand_filename(options.identity_files[i],
1248                     original_real_uid);
1249                 public = key_load_public(filename, NULL);
1250                 debug("identity file %s type %d", filename,
1251                     public ? public->type : -1);
1252                 xfree(options.identity_files[i]);
1253                 options.identity_files[i] = filename;
1254                 options.identity_keys[i] = public;
1255         }
1256 }
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