Annotation of src/usr.bin/ssh/ssh.c, Revision 1.105
1.1 deraadt 1: /*
1.32 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: * 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: *
1.64 deraadt 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: *
17: * Modified to work with SSL by Niels Provos <provos@citi.umich.edu>
18: * in Canada (German citizen).
19: *
20: * Redistribution and use in source and binary forms, with or without
21: * modification, are permitted provided that the following conditions
22: * are met:
23: * 1. Redistributions of source code must retain the above copyright
24: * notice, this list of conditions and the following disclaimer.
25: * 2. Redistributions in binary form must reproduce the above copyright
26: * notice, this list of conditions and the following disclaimer in the
27: * documentation and/or other materials provided with the distribution.
28: *
29: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
30: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
31: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
32: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
33: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
34: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
38: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.32 deraadt 39: */
1.1 deraadt 40:
41: #include "includes.h"
1.105 ! markus 42: RCSID("$OpenBSD: ssh.c,v 1.104 2001/03/08 21:42:32 markus Exp $");
1.49 markus 43:
44: #include <openssl/evp.h>
1.72 markus 45: #include <openssl/err.h>
1.1 deraadt 46:
1.84 markus 47: #include "ssh.h"
48: #include "ssh1.h"
49: #include "ssh2.h"
50: #include "compat.h"
51: #include "cipher.h"
1.1 deraadt 52: #include "xmalloc.h"
53: #include "packet.h"
54: #include "buffer.h"
55: #include "uidswap.h"
1.44 markus 56: #include "channels.h"
1.49 markus 57: #include "key.h"
1.58 markus 58: #include "authfd.h"
1.49 markus 59: #include "authfile.h"
1.83 markus 60: #include "pathnames.h"
1.81 markus 61: #include "clientloop.h"
1.84 markus 62: #include "log.h"
63: #include "readconf.h"
64: #include "sshconnect.h"
65: #include "tildexpand.h"
1.89 markus 66: #include "dispatch.h"
1.84 markus 67: #include "misc.h"
1.95 markus 68: #include "kex.h"
69: #include "mac.h"
1.49 markus 70:
71: extern char *__progname;
1.1 deraadt 72:
1.37 markus 73: /* Flag indicating whether IPv4 or IPv6. This can be set on the command line.
74: Default value is AF_UNSPEC means both IPv4 and IPv6. */
75: int IPv4or6 = AF_UNSPEC;
76:
1.31 markus 77: /* Flag indicating whether debug mode is on. This can be set on the command line. */
1.1 deraadt 78: int debug_flag = 0;
79:
1.46 markus 80: /* Flag indicating whether a tty should be allocated */
1.1 deraadt 81: int tty_flag = 0;
1.79 markus 82: int no_tty_flag = 0;
83: int force_tty_flag = 0;
1.1 deraadt 84:
1.45 markus 85: /* don't exec a shell */
86: int no_shell_flag = 0;
87:
1.33 markus 88: /*
89: * Flag indicating that nothing should be read from stdin. This can be set
90: * on the command line.
91: */
1.1 deraadt 92: int stdin_null_flag = 0;
93:
1.33 markus 94: /*
95: * Flag indicating that ssh should fork after authentication. This is useful
96: * so that the pasphrase can be entered manually, and then ssh goes to the
97: * background.
98: */
1.1 deraadt 99: int fork_after_authentication_flag = 0;
100:
1.33 markus 101: /*
102: * General data structure for command line options and options configurable
103: * in configuration files. See readconf.h.
104: */
1.1 deraadt 105: Options options;
106:
1.33 markus 107: /*
108: * Name of the host we are connecting to. This is the name given on the
109: * command line, or the HostName specified for the user-supplied name in a
110: * configuration file.
111: */
1.1 deraadt 112: char *host;
113:
1.22 provos 114: /* socket address the host resolves to */
1.37 markus 115: struct sockaddr_storage hostaddr;
1.22 provos 116:
1.33 markus 117: /*
118: * Flag to indicate that we have received a window change signal which has
119: * not yet been processed. This will cause a message indicating the new
120: * window size to be sent to the server a little later. This is volatile
121: * because this is updated in a signal handler.
122: */
1.1 deraadt 123: volatile int received_window_change_signal = 0;
124:
125: /* Host private key. */
1.105 ! markus 126: Key *host_private_key = NULL;
1.1 deraadt 127:
1.10 dugsong 128: /* Original real UID. */
129: uid_t original_real_uid;
1.1 deraadt 130:
1.45 markus 131: /* command to be executed */
132: Buffer command;
133:
1.85 djm 134: /* Should we execute a command or invoke a subsystem? */
135: int subsystem_flag = 0;
136:
1.1 deraadt 137: /* Prints a help message to the user. This function never returns. */
138:
1.2 provos 139: void
1.93 itojun 140: usage(void)
1.1 deraadt 141: {
1.76 markus 142: fprintf(stderr, "Usage: %s [options] host [command]\n", __progname);
1.31 markus 143: fprintf(stderr, "Options:\n");
144: fprintf(stderr, " -l user Log in using this user name.\n");
1.93 itojun 145: fprintf(stderr, " -n Redirect input from " _PATH_DEVNULL ".\n");
1.53 markus 146: fprintf(stderr, " -A Enable authentication agent forwarding.\n");
1.31 markus 147: fprintf(stderr, " -a Disable authentication agent forwarding.\n");
1.9 dugsong 148: #ifdef AFS
1.31 markus 149: fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n");
150: #endif /* AFS */
1.88 stevesk 151: fprintf(stderr, " -X Enable X11 connection forwarding.\n");
1.31 markus 152: fprintf(stderr, " -x Disable X11 connection forwarding.\n");
1.99 deraadt 153: fprintf(stderr, " -i file Identity for public key authentication "
154: "(default: ~/.ssh/identity)\n");
1.31 markus 155: fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n");
1.45 markus 156: fprintf(stderr, " -T Do not allocate a tty.\n");
1.31 markus 157: fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
1.66 markus 158: fprintf(stderr, " Multiple -v increases verbosity.\n");
1.31 markus 159: fprintf(stderr, " -V Display version number only.\n");
160: fprintf(stderr, " -P Don't allocate a privileged port.\n");
161: fprintf(stderr, " -q Quiet; don't display any warning messages.\n");
162: fprintf(stderr, " -f Fork into background after authentication.\n");
163: fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n");
164:
165: fprintf(stderr, " -c cipher Select encryption algorithm: "
1.99 deraadt 166: "``3des'', ``blowfish''\n");
1.102 stevesk 167: fprintf(stderr, " -m macs Specify MAC algorithms for protocol version 2.\n");
1.31 markus 168: fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n");
169: fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n");
170: fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n");
1.76 markus 171: fprintf(stderr, " These cause %s to listen for connections on a port, and\n", __progname);
1.31 markus 172: fprintf(stderr, " forward them to the other side by connecting to host:port.\n");
173: fprintf(stderr, " -C Enable compression.\n");
1.45 markus 174: fprintf(stderr, " -N Do not execute a shell or command.\n");
1.31 markus 175: fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n");
1.92 jakob 176: fprintf(stderr, " -1 Force protocol version 1.\n");
177: fprintf(stderr, " -2 Force protocol version 2.\n");
1.37 markus 178: fprintf(stderr, " -4 Use IPv4 only.\n");
179: fprintf(stderr, " -6 Use IPv6 only.\n");
1.31 markus 180: fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n");
1.85 djm 181: fprintf(stderr, " -s Invoke command (mandatory) as SSH2 subsystem.\n");
1.31 markus 182: exit(1);
1.1 deraadt 183: }
184:
1.32 deraadt 185: /*
186: * Connects to the given host using rsh (or prints an error message and exits
187: * if rsh is not available). This function never returns.
188: */
1.2 provos 189: void
1.31 markus 190: rsh_connect(char *host, char *user, Buffer * command)
1.1 deraadt 191: {
1.31 markus 192: char *args[10];
193: int i;
194:
195: log("Using rsh. WARNING: Connection will not be encrypted.");
196: /* Build argument list for rsh. */
197: i = 0;
198: args[i++] = _PATH_RSH;
199: /* host may have to come after user on some systems */
200: args[i++] = host;
201: if (user) {
202: args[i++] = "-l";
203: args[i++] = user;
204: }
205: if (buffer_len(command) > 0) {
206: buffer_append(command, "\0", 1);
207: args[i++] = buffer_ptr(command);
208: }
209: args[i++] = NULL;
210: if (debug_flag) {
211: for (i = 0; args[i]; i++) {
212: if (i != 0)
213: fprintf(stderr, " ");
214: fprintf(stderr, "%s", args[i]);
215: }
216: fprintf(stderr, "\n");
217: }
218: execv(_PATH_RSH, args);
219: perror(_PATH_RSH);
220: exit(1);
1.1 deraadt 221: }
222:
1.72 markus 223: int ssh_session(void);
224: int ssh_session2(void);
1.104 markus 225: void load_public_identity_files(void);
1.45 markus 226:
1.32 deraadt 227: /*
228: * Main program for the ssh client.
229: */
1.2 provos 230: int
231: main(int ac, char **av)
1.1 deraadt 232: {
1.45 markus 233: int i, opt, optind, exit_status, ok;
1.35 markus 234: u_short fwd_port, fwd_host_port;
1.31 markus 235: char *optarg, *cp, buf[256];
236: struct stat st;
1.98 markus 237: struct passwd *pw;
1.45 markus 238: int dummy;
1.31 markus 239: uid_t original_effective_uid;
240:
1.33 markus 241: /*
242: * Save the original real uid. It will be needed later (uid-swapping
243: * may clobber the real uid).
244: */
1.31 markus 245: original_real_uid = getuid();
246: original_effective_uid = geteuid();
247:
248: /* If we are installed setuid root be careful to not drop core. */
249: if (original_real_uid != original_effective_uid) {
250: struct rlimit rlim;
251: rlim.rlim_cur = rlim.rlim_max = 0;
252: if (setrlimit(RLIMIT_CORE, &rlim) < 0)
253: fatal("setrlimit failed: %.100s", strerror(errno));
1.1 deraadt 254: }
1.33 markus 255: /*
256: * Use uid-swapping to give up root privileges for the duration of
257: * option processing. We will re-instantiate the rights when we are
258: * ready to create the privileged port, and will permanently drop
259: * them when the port has been created (actually, when the connection
260: * has been made, as we may need to create the port several times).
261: */
1.31 markus 262: temporarily_use_uid(original_real_uid);
263:
1.33 markus 264: /*
265: * Set our umask to something reasonable, as some files are created
266: * with the default umask. This will make them world-readable but
267: * writable only by the owner, which is ok for all files for which we
268: * don't set the modes explicitly.
269: */
1.31 markus 270: umask(022);
271:
272: /* Initialize option structure to indicate that no values have been set. */
273: initialize_options(&options);
274:
275: /* Parse command-line arguments. */
276: host = NULL;
277:
278: for (optind = 1; optind < ac; optind++) {
279: if (av[optind][0] != '-') {
280: if (host)
281: break;
282: if ((cp = strchr(av[optind], '@'))) {
1.48 markus 283: if(cp == av[optind])
284: usage();
1.31 markus 285: options.user = av[optind];
286: *cp = '\0';
287: host = ++cp;
288: } else
289: host = av[optind];
290: continue;
291: }
292: opt = av[optind][1];
293: if (!opt)
294: usage();
1.95 markus 295: if (strchr("eilcmpLRo", opt)) { /* options with arguments */
1.31 markus 296: optarg = av[optind] + 2;
297: if (strcmp(optarg, "") == 0) {
298: if (optind >= ac - 1)
299: usage();
300: optarg = av[++optind];
301: }
302: } else {
303: if (av[optind][2])
304: usage();
305: optarg = NULL;
306: }
307: switch (opt) {
1.91 jakob 308: case '1':
309: options.protocol = SSH_PROTO_1;
310: break;
1.47 markus 311: case '2':
312: options.protocol = SSH_PROTO_2;
313: break;
1.37 markus 314: case '4':
315: IPv4or6 = AF_INET;
316: break;
317: case '6':
318: IPv4or6 = AF_INET6;
319: break;
1.31 markus 320: case 'n':
321: stdin_null_flag = 1;
322: break;
323: case 'f':
324: fork_after_authentication_flag = 1;
325: stdin_null_flag = 1;
326: break;
327: case 'x':
328: options.forward_x11 = 0;
329: break;
330: case 'X':
331: options.forward_x11 = 1;
332: break;
333: case 'g':
334: options.gateway_ports = 1;
335: break;
336: case 'P':
337: options.use_privileged_port = 0;
338: break;
339: case 'a':
340: options.forward_agent = 0;
1.53 markus 341: break;
342: case 'A':
343: options.forward_agent = 1;
1.31 markus 344: break;
1.9 dugsong 345: #ifdef AFS
1.31 markus 346: case 'k':
347: options.kerberos_tgt_passing = 0;
348: options.afs_token_passing = 0;
349: break;
1.1 deraadt 350: #endif
1.31 markus 351: case 'i':
352: if (stat(optarg, &st) < 0) {
353: fprintf(stderr, "Warning: Identity file %s does not exist.\n",
1.72 markus 354: optarg);
1.31 markus 355: break;
356: }
357: if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES)
358: fatal("Too many identity files specified (max %d)",
1.72 markus 359: SSH_MAX_IDENTITY_FILES);
360: options.identity_files[options.num_identity_files++] = xstrdup(optarg);
1.31 markus 361: break;
362: case 't':
1.79 markus 363: if (tty_flag)
364: force_tty_flag = 1;
1.31 markus 365: tty_flag = 1;
366: break;
367: case 'v':
1.66 markus 368: if (0 == debug_flag) {
369: debug_flag = 1;
370: options.log_level = SYSLOG_LEVEL_DEBUG1;
371: } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
372: options.log_level++;
373: break;
374: } else {
1.103 millert 375: fatal("Too high debugging level.");
1.66 markus 376: }
377: /* fallthrough */
1.31 markus 378: case 'V':
1.96 deraadt 379: fprintf(stderr,
380: "%s, SSH protocols %d.%d/%d.%d, OpenSSL 0x%8.8lx\n",
1.46 markus 381: SSH_VERSION,
382: PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
1.96 deraadt 383: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
384: SSLeay());
1.31 markus 385: if (opt == 'V')
386: exit(0);
387: break;
388: case 'q':
389: options.log_level = SYSLOG_LEVEL_QUIET;
390: break;
391: case 'e':
392: if (optarg[0] == '^' && optarg[2] == 0 &&
1.78 markus 393: (u_char) optarg[1] >= 64 && (u_char) optarg[1] < 128)
394: options.escape_char = (u_char) optarg[1] & 31;
1.31 markus 395: else if (strlen(optarg) == 1)
1.78 markus 396: options.escape_char = (u_char) optarg[0];
1.31 markus 397: else if (strcmp(optarg, "none") == 0)
398: options.escape_char = -2;
399: else {
400: fprintf(stderr, "Bad escape character '%s'.\n", optarg);
401: exit(1);
402: }
403: break;
404: case 'c':
1.49 markus 405: if (ciphers_valid(optarg)) {
406: /* SSH2 only */
407: options.ciphers = xstrdup(optarg);
1.51 markus 408: options.cipher = SSH_CIPHER_ILLEGAL;
1.49 markus 409: } else {
410: /* SSH1 only */
1.74 markus 411: options.cipher = cipher_number(optarg);
412: if (options.cipher == -1) {
1.49 markus 413: fprintf(stderr, "Unknown cipher type '%s'\n", optarg);
414: exit(1);
415: }
1.74 markus 416: if (options.cipher == SSH_CIPHER_3DES) {
417: options.ciphers = "3des-cbc";
418: } else if (options.cipher == SSH_CIPHER_BLOWFISH) {
419: options.ciphers = "blowfish-cbc";
420: } else {
421: options.ciphers = (char *)-1;
422: }
1.95 markus 423: }
424: break;
425: case 'm':
426: if (mac_valid(optarg))
427: options.macs = xstrdup(optarg);
428: else {
429: fprintf(stderr, "Unknown mac type '%s'\n", optarg);
430: exit(1);
1.31 markus 431: }
432: break;
433: case 'p':
434: options.port = atoi(optarg);
435: break;
436: case 'l':
437: options.user = optarg;
438: break;
439: case 'R':
1.37 markus 440: if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
441: &fwd_host_port) != 3 &&
442: sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
443: &fwd_host_port) != 3) {
1.31 markus 444: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
445: usage();
446: /* NOTREACHED */
447: }
448: add_remote_forward(&options, fwd_port, buf, fwd_host_port);
449: break;
450: case 'L':
1.37 markus 451: if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
452: &fwd_host_port) != 3 &&
453: sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
454: &fwd_host_port) != 3) {
1.31 markus 455: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
456: usage();
457: /* NOTREACHED */
458: }
459: add_local_forward(&options, fwd_port, buf, fwd_host_port);
460: break;
461: case 'C':
462: options.compression = 1;
463: break;
1.45 markus 464: case 'N':
465: no_shell_flag = 1;
466: no_tty_flag = 1;
467: break;
468: case 'T':
469: no_tty_flag = 1;
470: break;
1.31 markus 471: case 'o':
472: dummy = 1;
473: if (process_config_line(&options, host ? host : "", optarg,
474: "command-line", 0, &dummy) != 0)
475: exit(1);
476: break;
1.85 djm 477: case 's':
478: subsystem_flag = 1;
479: break;
1.31 markus 480: default:
481: usage();
1.1 deraadt 482: }
1.31 markus 483: }
484:
485: /* Check that we got a host name. */
486: if (!host)
487: usage();
488:
1.54 markus 489: SSLeay_add_all_algorithms();
1.72 markus 490: ERR_load_crypto_strings();
1.31 markus 491:
492: /* Initialize the command to execute on remote host. */
493: buffer_init(&command);
1.1 deraadt 494:
1.33 markus 495: /*
496: * Save the command to execute on the remote host in a buffer. There
497: * is no limit on the length of the command, except by the maximum
498: * packet size. Also sets the tty flag if there is no command.
499: */
1.31 markus 500: if (optind == ac) {
501: /* No command specified - execute shell on a tty. */
502: tty_flag = 1;
1.85 djm 503: if (subsystem_flag) {
504: fprintf(stderr, "You must specify a subsystem to invoke.");
505: usage();
506: }
1.31 markus 507: } else {
508: /* A command has been specified. Store it into the
509: buffer. */
510: for (i = optind; i < ac; i++) {
511: if (i > optind)
512: buffer_append(&command, " ", 1);
513: buffer_append(&command, av[i], strlen(av[i]));
514: }
515: }
516:
517: /* Cannot fork to background if no command. */
1.63 markus 518: if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
1.31 markus 519: fatal("Cannot fork into background without a command to execute.");
520:
521: /* Allocate a tty by default if no command specified. */
522: if (buffer_len(&command) == 0)
523: tty_flag = 1;
524:
1.75 markus 525: /* Force no tty*/
526: if (no_tty_flag)
527: tty_flag = 0;
1.31 markus 528: /* Do not allocate a tty if stdin is not a tty. */
1.79 markus 529: if (!isatty(fileno(stdin)) && !force_tty_flag) {
1.31 markus 530: if (tty_flag)
1.103 millert 531: log("Pseudo-terminal will not be allocated because stdin is not a terminal.");
1.31 markus 532: tty_flag = 0;
533: }
1.45 markus 534:
1.31 markus 535: /* Get user data. */
536: pw = getpwuid(original_real_uid);
537: if (!pw) {
1.103 millert 538: log("You don't exist, go away!");
1.31 markus 539: exit(1);
540: }
541: /* Take a copy of the returned structure. */
1.98 markus 542: pw = pwcopy(pw);
1.31 markus 543:
1.101 markus 544: /*
545: * Initialize "log" output. Since we are the client all output
546: * actually goes to stderr.
547: */
548: log_init(av[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1);
1.31 markus 549:
550: /* Read per-user configuration file. */
1.83 markus 551: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, _PATH_SSH_USER_CONFFILE);
1.31 markus 552: read_config_file(buf, host, &options);
553:
554: /* Read systemwide configuration file. */
1.83 markus 555: read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
1.31 markus 556:
557: /* Fill configuration defaults. */
558: fill_default_options(&options);
559:
560: /* reinit */
1.101 markus 561: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
1.31 markus 562:
563: if (options.user == NULL)
564: options.user = xstrdup(pw->pw_name);
565:
566: if (options.hostname != NULL)
567: host = options.hostname;
568:
569: /* Disable rhosts authentication if not running as root. */
570: if (original_effective_uid != 0 || !options.use_privileged_port) {
1.77 markus 571: debug("Rhosts Authentication disabled, "
1.71 markus 572: "originating port will not be trusted.");
1.31 markus 573: options.rhosts_authentication = 0;
574: }
1.33 markus 575: /*
576: * If using rsh has been selected, exec it now (without trying
577: * anything else). Note that we must release privileges first.
578: */
1.31 markus 579: if (options.use_rsh) {
1.33 markus 580: /*
581: * Restore our superuser privileges. This must be done
582: * before permanently setting the uid.
583: */
1.31 markus 584: restore_uid();
585:
586: /* Switch to the original uid permanently. */
587: permanently_set_uid(original_real_uid);
588:
589: /* Execute rsh. */
590: rsh_connect(host, options.user, &command);
591: fatal("rsh_connect returned");
592: }
593: /* Restore our superuser privileges. */
594: restore_uid();
595:
1.77 markus 596: /* Open a connection to the remote host. */
1.31 markus 597:
598: ok = ssh_connect(host, &hostaddr, options.port,
1.77 markus 599: options.connection_attempts,
600: original_effective_uid != 0 || !options.use_privileged_port,
601: original_real_uid,
602: options.proxy_command);
1.31 markus 603:
1.33 markus 604: /*
605: * If we successfully made the connection, load the host private key
606: * in case we will need it later for combined rsa-rhosts
607: * authentication. This must be done before releasing extra
608: * privileges, because the file is only readable by root.
609: */
1.49 markus 610: if (ok && (options.protocol & SSH_PROTO_1)) {
1.105 ! markus 611: host_private_key = key_load_private_type(KEY_RSA1,
! 612: _PATH_HOST_KEY_FILE, "", NULL);
1.31 markus 613: }
1.33 markus 614: /*
615: * Get rid of any extra privileges that we may have. We will no
616: * longer need them. Also, extra privileges could make it very hard
617: * to read identity files and other non-world-readable files from the
618: * user's home directory if it happens to be on a NFS volume where
619: * root is mapped to nobody.
620: */
621:
622: /*
623: * Note that some legacy systems need to postpone the following call
624: * to permanently_set_uid() until the private hostkey is destroyed
625: * with RSA_free(). Otherwise the calling user could ptrace() the
626: * process, read the private hostkey and impersonate the host.
627: * OpenBSD does not allow ptracing of setuid processes.
628: */
1.31 markus 629: permanently_set_uid(original_real_uid);
630:
1.33 markus 631: /*
632: * Now that we are back to our own permissions, create ~/.ssh
633: * directory if it doesn\'t already exist.
634: */
1.83 markus 635: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, _PATH_SSH_USER_DIR);
1.31 markus 636: if (stat(buf, &st) < 0)
1.57 djm 637: if (mkdir(buf, 0700) < 0)
1.31 markus 638: error("Could not create directory '%.200s'.", buf);
639:
640: /* Check if the connection failed, and try "rsh" if appropriate. */
641: if (!ok) {
642: if (options.port != 0)
1.35 markus 643: log("Secure connection to %.100s on port %hu refused%.100s.",
1.31 markus 644: host, options.port,
645: options.fallback_to_rsh ? "; reverting to insecure method" : "");
646: else
647: log("Secure connection to %.100s refused%.100s.", host,
648: options.fallback_to_rsh ? "; reverting to insecure method" : "");
649:
650: if (options.fallback_to_rsh) {
651: rsh_connect(host, options.user, &command);
652: fatal("rsh_connect returned");
653: }
654: exit(1);
655: }
1.104 markus 656: /* load options.identity_files */
657: load_public_identity_files();
658:
659: /* Expand ~ in known host file names. */
660: /* XXX mem-leaks: */
1.72 markus 661: options.system_hostfile =
662: tilde_expand_filename(options.system_hostfile, original_real_uid);
663: options.user_hostfile =
664: tilde_expand_filename(options.user_hostfile, original_real_uid);
665: options.system_hostfile2 =
666: tilde_expand_filename(options.system_hostfile2, original_real_uid);
667: options.user_hostfile2 =
668: tilde_expand_filename(options.user_hostfile2, original_real_uid);
1.31 markus 669:
670: /* Log into the remote system. This never returns if the login fails. */
1.105 ! markus 671: ssh_login(host_private_key, host, (struct sockaddr *)&hostaddr,
! 672: original_real_uid);
1.31 markus 673:
674: /* We no longer need the host private key. Clear it now. */
1.105 ! markus 675: if (host_private_key != NULL)
! 676: key_free(host_private_key); /* Destroys contents safely */
1.31 markus 677:
1.45 markus 678: exit_status = compat20 ? ssh_session2() : ssh_session();
679: packet_close();
680: return exit_status;
681: }
682:
1.50 markus 683: void
684: x11_get_proto(char *proto, int proto_len, char *data, int data_len)
685: {
686: char line[512];
687: FILE *f;
688: int got_data = 0, i;
689:
1.55 markus 690: if (options.xauth_location) {
691: /* Try to get Xauthority information for the display. */
1.93 itojun 692: snprintf(line, sizeof line, "%.100s list %.200s 2>" _PATH_DEVNULL,
1.55 markus 693: options.xauth_location, getenv("DISPLAY"));
694: f = popen(line, "r");
695: if (f && fgets(line, sizeof(line), f) &&
696: sscanf(line, "%*s %s %s", proto, data) == 2)
697: got_data = 1;
698: if (f)
699: pclose(f);
700: }
1.50 markus 701: /*
702: * If we didn't get authentication data, just make up some
703: * data. The forwarding code will check the validity of the
704: * response anyway, and substitute this data. The X11
705: * server, however, will ignore this fake data and use
706: * whatever authentication mechanisms it was using otherwise
707: * for the local connection.
708: */
709: if (!got_data) {
710: u_int32_t rand = 0;
711:
712: strlcpy(proto, "MIT-MAGIC-COOKIE-1", proto_len);
713: for (i = 0; i < 16; i++) {
714: if (i % 4 == 0)
715: rand = arc4random();
716: snprintf(data + 2 * i, data_len - 2 * i, "%02x", rand & 0xff);
717: rand >>= 8;
718: }
719: }
720: }
721:
1.70 markus 722: void
723: ssh_init_forwarding(void)
724: {
1.86 markus 725: int success = 0;
1.70 markus 726: int i;
1.86 markus 727:
1.70 markus 728: /* Initiate local TCP/IP port forwardings. */
729: for (i = 0; i < options.num_local_forwards; i++) {
730: debug("Connections to local port %d forwarded to remote address %.200s:%d",
731: options.local_forwards[i].port,
732: options.local_forwards[i].host,
733: options.local_forwards[i].host_port);
1.86 markus 734: success += channel_request_local_forwarding(
1.70 markus 735: options.local_forwards[i].port,
736: options.local_forwards[i].host,
737: options.local_forwards[i].host_port,
738: options.gateway_ports);
739: }
1.86 markus 740: if (i > 0 && success == 0)
741: error("Could not request local forwarding.");
1.70 markus 742:
743: /* Initiate remote TCP/IP port forwardings. */
744: for (i = 0; i < options.num_remote_forwards; i++) {
745: debug("Connections to remote port %d forwarded to local address %.200s:%d",
746: options.remote_forwards[i].port,
747: options.remote_forwards[i].host,
748: options.remote_forwards[i].host_port);
749: channel_request_remote_forwarding(
750: options.remote_forwards[i].port,
751: options.remote_forwards[i].host,
752: options.remote_forwards[i].host_port);
753: }
754: }
755:
756: void
757: check_agent_present(void)
758: {
759: if (options.forward_agent) {
760: /* Clear agent forwarding if we don\'t have an agent. */
761: int authfd = ssh_get_authentication_socket();
762: if (authfd < 0)
763: options.forward_agent = 0;
764: else
765: ssh_close_authentication_socket(authfd);
766: }
767: }
768:
1.45 markus 769: int
770: ssh_session(void)
771: {
772: int type;
773: int plen;
774: int interactive = 0;
775: int have_tty = 0;
776: struct winsize ws;
777: char *cp;
778:
1.31 markus 779: /* Enable compression if requested. */
780: if (options.compression) {
781: debug("Requesting compression at level %d.", options.compression_level);
782:
783: if (options.compression_level < 1 || options.compression_level > 9)
784: fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
785:
786: /* Send the request. */
787: packet_start(SSH_CMSG_REQUEST_COMPRESSION);
788: packet_put_int(options.compression_level);
789: packet_send();
790: packet_write_wait();
791: type = packet_read(&plen);
792: if (type == SSH_SMSG_SUCCESS)
793: packet_start_compression(options.compression_level);
794: else if (type == SSH_SMSG_FAILURE)
795: log("Warning: Remote host refused compression.");
796: else
797: packet_disconnect("Protocol error waiting for compression response.");
798: }
799: /* Allocate a pseudo tty if appropriate. */
800: if (tty_flag) {
801: debug("Requesting pty.");
802:
803: /* Start the packet. */
804: packet_start(SSH_CMSG_REQUEST_PTY);
805:
806: /* Store TERM in the packet. There is no limit on the
807: length of the string. */
808: cp = getenv("TERM");
809: if (!cp)
810: cp = "";
811: packet_put_string(cp, strlen(cp));
812:
813: /* Store window size in the packet. */
814: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
815: memset(&ws, 0, sizeof(ws));
816: packet_put_int(ws.ws_row);
817: packet_put_int(ws.ws_col);
818: packet_put_int(ws.ws_xpixel);
819: packet_put_int(ws.ws_ypixel);
820:
821: /* Store tty modes in the packet. */
822: tty_make_modes(fileno(stdin));
823:
824: /* Send the packet, and wait for it to leave. */
825: packet_send();
826: packet_write_wait();
827:
828: /* Read response from the server. */
829: type = packet_read(&plen);
1.43 markus 830: if (type == SSH_SMSG_SUCCESS) {
1.31 markus 831: interactive = 1;
1.45 markus 832: have_tty = 1;
1.43 markus 833: } else if (type == SSH_SMSG_FAILURE)
1.31 markus 834: log("Warning: Remote host failed or refused to allocate a pseudo tty.");
835: else
836: packet_disconnect("Protocol error waiting for pty request response.");
837: }
838: /* Request X11 forwarding if enabled and DISPLAY is set. */
839: if (options.forward_x11 && getenv("DISPLAY") != NULL) {
1.50 markus 840: char proto[512], data[512];
841: /* Get reasonable local authentication information. */
842: x11_get_proto(proto, sizeof proto, data, sizeof data);
843: /* Request forwarding with authentication spoofing. */
1.31 markus 844: debug("Requesting X11 forwarding with authentication spoofing.");
1.50 markus 845: x11_request_forwarding_with_spoofing(0, proto, data);
1.31 markus 846:
847: /* Read response from the server. */
848: type = packet_read(&plen);
849: if (type == SSH_SMSG_SUCCESS) {
850: interactive = 1;
1.50 markus 851: } else if (type == SSH_SMSG_FAILURE) {
1.31 markus 852: log("Warning: Remote host denied X11 forwarding.");
1.50 markus 853: } else {
1.31 markus 854: packet_disconnect("Protocol error waiting for X11 forwarding");
1.50 markus 855: }
1.31 markus 856: }
857: /* Tell the packet module whether this is an interactive session. */
1.80 markus 858: packet_set_interactive(interactive);
1.31 markus 859:
860: /* Request authentication agent forwarding if appropriate. */
1.70 markus 861: check_agent_present();
862:
1.31 markus 863: if (options.forward_agent) {
864: debug("Requesting authentication agent forwarding.");
865: auth_request_forwarding();
866:
867: /* Read response from the server. */
868: type = packet_read(&plen);
869: packet_integrity_check(plen, 0, type);
870: if (type != SSH_SMSG_SUCCESS)
871: log("Warning: Remote host denied authentication agent forwarding.");
872: }
873:
1.70 markus 874: /* Initiate port forwardings. */
875: ssh_init_forwarding();
1.34 markus 876:
877: /* If requested, let ssh continue in the background. */
1.48 markus 878: if (fork_after_authentication_flag)
1.34 markus 879: if (daemon(1, 1) < 0)
880: fatal("daemon() failed: %.200s", strerror(errno));
1.31 markus 881:
1.33 markus 882: /*
883: * If a command was specified on the command line, execute the
884: * command now. Otherwise request the server to start a shell.
885: */
1.31 markus 886: if (buffer_len(&command) > 0) {
887: int len = buffer_len(&command);
888: if (len > 900)
889: len = 900;
890: debug("Sending command: %.*s", len, buffer_ptr(&command));
891: packet_start(SSH_CMSG_EXEC_CMD);
892: packet_put_string(buffer_ptr(&command), buffer_len(&command));
893: packet_send();
894: packet_write_wait();
895: } else {
896: debug("Requesting shell.");
897: packet_start(SSH_CMSG_EXEC_SHELL);
898: packet_send();
899: packet_write_wait();
900: }
901:
902: /* Enter the interactive session. */
1.60 markus 903: return client_loop(have_tty, tty_flag ? options.escape_char : -1, 0);
1.45 markus 904: }
905:
906: void
1.89 markus 907: client_subsystem_reply(int type, int plen, void *ctxt)
908: {
909: int id, len;
910:
911: id = packet_get_int();
912: len = buffer_len(&command);
1.100 markus 913: if (len > 900)
914: len = 900;
1.89 markus 915: packet_done();
916: if (type == SSH2_MSG_CHANNEL_FAILURE)
917: fatal("Request for subsystem '%.*s' failed on channel %d",
918: len, buffer_ptr(&command), id);
919: }
920:
921: void
1.70 markus 922: ssh_session2_callback(int id, void *arg)
1.45 markus 923: {
924: int len;
1.80 markus 925: int interactive = 0;
926:
1.87 deraadt 927: debug("client_init id %d arg %ld", id, (long)arg);
1.31 markus 928:
1.45 markus 929: if (no_shell_flag)
930: goto done;
931:
932: if (tty_flag) {
933: struct winsize ws;
934: char *cp;
935: cp = getenv("TERM");
936: if (!cp)
937: cp = "";
938: /* Store window size in the packet. */
939: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
940: memset(&ws, 0, sizeof(ws));
941:
942: channel_request_start(id, "pty-req", 0);
943: packet_put_cstring(cp);
944: packet_put_int(ws.ws_col);
945: packet_put_int(ws.ws_row);
946: packet_put_int(ws.ws_xpixel);
947: packet_put_int(ws.ws_ypixel);
948: packet_put_cstring(""); /* XXX: encode terminal modes */
949: packet_send();
1.80 markus 950: interactive = 1;
1.45 markus 951: /* XXX wait for reply */
952: }
1.50 markus 953: if (options.forward_x11 &&
954: getenv("DISPLAY") != NULL) {
955: char proto[512], data[512];
956: /* Get reasonable local authentication information. */
957: x11_get_proto(proto, sizeof proto, data, sizeof data);
958: /* Request forwarding with authentication spoofing. */
959: debug("Requesting X11 forwarding with authentication spoofing.");
960: x11_request_forwarding_with_spoofing(id, proto, data);
1.80 markus 961: interactive = 1;
1.50 markus 962: /* XXX wait for reply */
963: }
964:
1.70 markus 965: check_agent_present();
966: if (options.forward_agent) {
967: debug("Requesting authentication agent forwarding.");
968: channel_request_start(id, "auth-agent-req@openssh.com", 0);
969: packet_send();
970: }
971:
1.45 markus 972: len = buffer_len(&command);
973: if (len > 0) {
974: if (len > 900)
975: len = 900;
1.85 djm 976: if (subsystem_flag) {
977: debug("Sending subsystem: %.*s", len, buffer_ptr(&command));
1.89 markus 978: channel_request_start(id, "subsystem", /*want reply*/ 1);
979: /* register callback for reply */
980: /* XXX we asume that client_loop has already been called */
981: dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
982: dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1.85 djm 983: } else {
984: debug("Sending command: %.*s", len, buffer_ptr(&command));
985: channel_request_start(id, "exec", 0);
986: }
1.100 markus 987: packet_put_string(buffer_ptr(&command), buffer_len(&command));
1.45 markus 988: packet_send();
989: } else {
990: channel_request(id, "shell", 0);
991: }
992: /* channel_callback(id, SSH2_MSG_OPEN_CONFIGMATION, client_init, 0); */
1.90 markus 993:
1.45 markus 994: done:
995: /* register different callback, etc. XXX */
1.80 markus 996: packet_set_interactive(interactive);
1.45 markus 997: }
998:
999: int
1000: ssh_session2(void)
1001: {
1002: int window, packetmax, id;
1.60 markus 1003: int in, out, err;
1004:
1.62 markus 1005: if (stdin_null_flag) {
1.93 itojun 1006: in = open(_PATH_DEVNULL, O_RDONLY);
1.62 markus 1007: } else {
1008: in = dup(STDIN_FILENO);
1009: }
1.60 markus 1010: out = dup(STDOUT_FILENO);
1011: err = dup(STDERR_FILENO);
1.45 markus 1012:
1013: if (in < 0 || out < 0 || err < 0)
1.62 markus 1014: fatal("dup() in/out/err failed");
1.45 markus 1015:
1.69 markus 1016: /* enable nonblocking unless tty */
1017: if (!isatty(in))
1018: set_nonblock(in);
1019: if (!isatty(out))
1020: set_nonblock(out);
1021: if (!isatty(err))
1022: set_nonblock(err);
1023:
1.70 markus 1024: /* XXX should be pre-session */
1025: ssh_init_forwarding();
1.88 stevesk 1026:
1.62 markus 1027: /* If requested, let ssh continue in the background. */
1028: if (fork_after_authentication_flag)
1029: if (daemon(1, 1) < 0)
1030: fatal("daemon() failed: %.200s", strerror(errno));
1031:
1.65 markus 1032: window = CHAN_SES_WINDOW_DEFAULT;
1033: packetmax = CHAN_SES_PACKET_DEFAULT;
1034: if (!tty_flag) {
1.45 markus 1035: window *= 2;
1.65 markus 1036: packetmax *=2;
1.45 markus 1037: }
1038: id = channel_new(
1039: "session", SSH_CHANNEL_OPENING, in, out, err,
1.65 markus 1040: window, packetmax, CHAN_EXTENDED_WRITE,
1.69 markus 1041: xstrdup("client-session"), /*nonblock*/0);
1.45 markus 1042:
1043: channel_open(id);
1.70 markus 1044: channel_register_callback(id, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION,
1045: ssh_session2_callback, (void *)0);
1.31 markus 1046:
1.60 markus 1047: return client_loop(tty_flag, tty_flag ? options.escape_char : -1, id);
1.72 markus 1048: }
1049:
1.104 markus 1050: void
1051: load_public_identity_files(void)
1052: {
1053: char *filename;
1054: Key *public;
1055: int i;
1056:
1057: for (i = 0; i < options.num_identity_files; i++) {
1058: filename = tilde_expand_filename(options.identity_files[i],
1059: original_real_uid);
1.105 ! markus 1060: public = key_load_public(filename, NULL);
1.104 markus 1061: debug("identity file %s type %d", filename,
1062: public ? public->type : -1);
1063: xfree(options.identity_files[i]);
1064: options.identity_files[i] = filename;
1065: options.identity_keys[i] = public;
1066: }
1.1 deraadt 1067: }
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