Annotation of src/usr.bin/ssh/ssh.c, Revision 1.116
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"
1.116 ! markus 42: RCSID("$OpenBSD: ssh.c,v 1.115 2001/04/14 16:33:20 stevesk 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"
1.115 stevesk 70: #include "sshtty.h"
1.49 markus 71:
72: extern char *__progname;
1.1 deraadt 73:
1.37 markus 74: /* Flag indicating whether IPv4 or IPv6. This can be set on the command line.
75: Default value is AF_UNSPEC means both IPv4 and IPv6. */
76: int IPv4or6 = AF_UNSPEC;
77:
1.31 markus 78: /* Flag indicating whether debug mode is on. This can be set on the command line. */
1.1 deraadt 79: int debug_flag = 0;
80:
1.46 markus 81: /* Flag indicating whether a tty should be allocated */
1.1 deraadt 82: int tty_flag = 0;
1.79 markus 83: int no_tty_flag = 0;
84: int force_tty_flag = 0;
1.1 deraadt 85:
1.45 markus 86: /* don't exec a shell */
87: int no_shell_flag = 0;
88:
1.33 markus 89: /*
90: * Flag indicating that nothing should be read from stdin. This can be set
91: * on the command line.
92: */
1.1 deraadt 93: int stdin_null_flag = 0;
94:
1.33 markus 95: /*
96: * Flag indicating that ssh should fork after authentication. This is useful
97: * so that the pasphrase can be entered manually, and then ssh goes to the
98: * background.
99: */
1.1 deraadt 100: int fork_after_authentication_flag = 0;
101:
1.33 markus 102: /*
103: * General data structure for command line options and options configurable
104: * in configuration files. See readconf.h.
105: */
1.1 deraadt 106: Options options;
107:
1.33 markus 108: /*
109: * Name of the host we are connecting to. This is the name given on the
110: * command line, or the HostName specified for the user-supplied name in a
111: * configuration file.
112: */
1.1 deraadt 113: char *host;
114:
1.22 provos 115: /* socket address the host resolves to */
1.37 markus 116: struct sockaddr_storage hostaddr;
1.22 provos 117:
1.33 markus 118: /*
119: * Flag to indicate that we have received a window change signal which has
120: * not yet been processed. This will cause a message indicating the new
121: * window size to be sent to the server a little later. This is volatile
122: * because this is updated in a signal handler.
123: */
1.1 deraadt 124: volatile int received_window_change_signal = 0;
125:
1.112 markus 126: /* Private host keys. */
127: struct {
128: Key **keys;
129: int nkeys;
130: } sensitive_data;
1.1 deraadt 131:
1.10 dugsong 132: /* Original real UID. */
133: uid_t original_real_uid;
1.1 deraadt 134:
1.45 markus 135: /* command to be executed */
136: Buffer command;
137:
1.85 djm 138: /* Should we execute a command or invoke a subsystem? */
139: int subsystem_flag = 0;
140:
1.1 deraadt 141: /* Prints a help message to the user. This function never returns. */
142:
1.2 provos 143: void
1.93 itojun 144: usage(void)
1.1 deraadt 145: {
1.76 markus 146: fprintf(stderr, "Usage: %s [options] host [command]\n", __progname);
1.31 markus 147: fprintf(stderr, "Options:\n");
148: fprintf(stderr, " -l user Log in using this user name.\n");
1.93 itojun 149: fprintf(stderr, " -n Redirect input from " _PATH_DEVNULL ".\n");
1.53 markus 150: fprintf(stderr, " -A Enable authentication agent forwarding.\n");
1.31 markus 151: fprintf(stderr, " -a Disable authentication agent forwarding.\n");
1.9 dugsong 152: #ifdef AFS
1.31 markus 153: fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n");
154: #endif /* AFS */
1.88 stevesk 155: fprintf(stderr, " -X Enable X11 connection forwarding.\n");
1.31 markus 156: fprintf(stderr, " -x Disable X11 connection forwarding.\n");
1.99 deraadt 157: fprintf(stderr, " -i file Identity for public key authentication "
158: "(default: ~/.ssh/identity)\n");
1.31 markus 159: fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n");
1.45 markus 160: fprintf(stderr, " -T Do not allocate a tty.\n");
1.31 markus 161: fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
1.66 markus 162: fprintf(stderr, " Multiple -v increases verbosity.\n");
1.31 markus 163: fprintf(stderr, " -V Display version number only.\n");
164: fprintf(stderr, " -P Don't allocate a privileged port.\n");
165: fprintf(stderr, " -q Quiet; don't display any warning messages.\n");
166: fprintf(stderr, " -f Fork into background after authentication.\n");
167: fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n");
168:
169: fprintf(stderr, " -c cipher Select encryption algorithm: "
1.99 deraadt 170: "``3des'', ``blowfish''\n");
1.102 stevesk 171: fprintf(stderr, " -m macs Specify MAC algorithms for protocol version 2.\n");
1.31 markus 172: fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n");
173: fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n");
174: fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n");
1.76 markus 175: fprintf(stderr, " These cause %s to listen for connections on a port, and\n", __progname);
1.31 markus 176: fprintf(stderr, " forward them to the other side by connecting to host:port.\n");
177: fprintf(stderr, " -C Enable compression.\n");
1.45 markus 178: fprintf(stderr, " -N Do not execute a shell or command.\n");
1.31 markus 179: fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n");
1.92 jakob 180: fprintf(stderr, " -1 Force protocol version 1.\n");
181: fprintf(stderr, " -2 Force protocol version 2.\n");
1.37 markus 182: fprintf(stderr, " -4 Use IPv4 only.\n");
183: fprintf(stderr, " -6 Use IPv6 only.\n");
1.31 markus 184: fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n");
1.85 djm 185: fprintf(stderr, " -s Invoke command (mandatory) as SSH2 subsystem.\n");
1.31 markus 186: exit(1);
1.1 deraadt 187: }
188:
1.32 deraadt 189: /*
190: * Connects to the given host using rsh (or prints an error message and exits
191: * if rsh is not available). This function never returns.
192: */
1.2 provos 193: void
1.31 markus 194: rsh_connect(char *host, char *user, Buffer * command)
1.1 deraadt 195: {
1.31 markus 196: char *args[10];
197: int i;
198:
199: log("Using rsh. WARNING: Connection will not be encrypted.");
200: /* Build argument list for rsh. */
201: i = 0;
202: args[i++] = _PATH_RSH;
203: /* host may have to come after user on some systems */
204: args[i++] = host;
205: if (user) {
206: args[i++] = "-l";
207: args[i++] = user;
208: }
209: if (buffer_len(command) > 0) {
210: buffer_append(command, "\0", 1);
211: args[i++] = buffer_ptr(command);
212: }
213: args[i++] = NULL;
214: if (debug_flag) {
215: for (i = 0; args[i]; i++) {
216: if (i != 0)
217: fprintf(stderr, " ");
218: fprintf(stderr, "%s", args[i]);
219: }
220: fprintf(stderr, "\n");
221: }
222: execv(_PATH_RSH, args);
223: perror(_PATH_RSH);
224: exit(1);
1.1 deraadt 225: }
226:
1.72 markus 227: int ssh_session(void);
228: int ssh_session2(void);
1.104 markus 229: void load_public_identity_files(void);
1.45 markus 230:
1.32 deraadt 231: /*
232: * Main program for the ssh client.
233: */
1.2 provos 234: int
235: main(int ac, char **av)
1.1 deraadt 236: {
1.45 markus 237: int i, opt, optind, exit_status, ok;
1.35 markus 238: u_short fwd_port, fwd_host_port;
1.113 stevesk 239: char *optarg, *cp, buf[256];
1.31 markus 240: struct stat st;
1.98 markus 241: struct passwd *pw;
1.45 markus 242: int dummy;
1.31 markus 243: uid_t original_effective_uid;
244:
1.33 markus 245: /*
246: * Save the original real uid. It will be needed later (uid-swapping
247: * may clobber the real uid).
248: */
1.31 markus 249: original_real_uid = getuid();
250: original_effective_uid = geteuid();
251:
252: /* If we are installed setuid root be careful to not drop core. */
253: if (original_real_uid != original_effective_uid) {
254: struct rlimit rlim;
255: rlim.rlim_cur = rlim.rlim_max = 0;
256: if (setrlimit(RLIMIT_CORE, &rlim) < 0)
257: fatal("setrlimit failed: %.100s", strerror(errno));
1.1 deraadt 258: }
1.107 markus 259: /* Get user data. */
260: pw = getpwuid(original_real_uid);
261: if (!pw) {
262: log("You don't exist, go away!");
263: exit(1);
264: }
265: /* Take a copy of the returned structure. */
266: pw = pwcopy(pw);
267:
1.33 markus 268: /*
269: * Use uid-swapping to give up root privileges for the duration of
270: * option processing. We will re-instantiate the rights when we are
271: * ready to create the privileged port, and will permanently drop
272: * them when the port has been created (actually, when the connection
273: * has been made, as we may need to create the port several times).
274: */
1.107 markus 275: temporarily_use_uid(pw);
1.31 markus 276:
1.33 markus 277: /*
278: * Set our umask to something reasonable, as some files are created
279: * with the default umask. This will make them world-readable but
280: * writable only by the owner, which is ok for all files for which we
281: * don't set the modes explicitly.
282: */
1.31 markus 283: umask(022);
284:
285: /* Initialize option structure to indicate that no values have been set. */
286: initialize_options(&options);
287:
288: /* Parse command-line arguments. */
289: host = NULL;
290:
291: for (optind = 1; optind < ac; optind++) {
292: if (av[optind][0] != '-') {
293: if (host)
294: break;
295: if ((cp = strchr(av[optind], '@'))) {
1.48 markus 296: if(cp == av[optind])
297: usage();
1.31 markus 298: options.user = av[optind];
299: *cp = '\0';
300: host = ++cp;
301: } else
302: host = av[optind];
303: continue;
304: }
305: opt = av[optind][1];
306: if (!opt)
307: usage();
1.108 markus 308: if (strchr("eilcmpLRDo", opt)) { /* options with arguments */
1.31 markus 309: optarg = av[optind] + 2;
310: if (strcmp(optarg, "") == 0) {
311: if (optind >= ac - 1)
312: usage();
313: optarg = av[++optind];
314: }
315: } else {
316: if (av[optind][2])
317: usage();
318: optarg = NULL;
319: }
320: switch (opt) {
1.91 jakob 321: case '1':
322: options.protocol = SSH_PROTO_1;
323: break;
1.47 markus 324: case '2':
325: options.protocol = SSH_PROTO_2;
326: break;
1.37 markus 327: case '4':
328: IPv4or6 = AF_INET;
329: break;
330: case '6':
331: IPv4or6 = AF_INET6;
332: break;
1.31 markus 333: case 'n':
334: stdin_null_flag = 1;
335: break;
336: case 'f':
337: fork_after_authentication_flag = 1;
338: stdin_null_flag = 1;
339: break;
340: case 'x':
341: options.forward_x11 = 0;
342: break;
343: case 'X':
344: options.forward_x11 = 1;
345: break;
346: case 'g':
347: options.gateway_ports = 1;
348: break;
349: case 'P':
350: options.use_privileged_port = 0;
351: break;
352: case 'a':
353: options.forward_agent = 0;
1.53 markus 354: break;
355: case 'A':
356: options.forward_agent = 1;
1.31 markus 357: break;
1.9 dugsong 358: #ifdef AFS
1.31 markus 359: case 'k':
360: options.kerberos_tgt_passing = 0;
361: options.afs_token_passing = 0;
362: break;
1.1 deraadt 363: #endif
1.31 markus 364: case 'i':
365: if (stat(optarg, &st) < 0) {
366: fprintf(stderr, "Warning: Identity file %s does not exist.\n",
1.72 markus 367: optarg);
1.31 markus 368: break;
369: }
370: if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES)
371: fatal("Too many identity files specified (max %d)",
1.72 markus 372: SSH_MAX_IDENTITY_FILES);
373: options.identity_files[options.num_identity_files++] = xstrdup(optarg);
1.31 markus 374: break;
375: case 't':
1.79 markus 376: if (tty_flag)
377: force_tty_flag = 1;
1.31 markus 378: tty_flag = 1;
379: break;
380: case 'v':
1.66 markus 381: if (0 == debug_flag) {
382: debug_flag = 1;
383: options.log_level = SYSLOG_LEVEL_DEBUG1;
384: } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
385: options.log_level++;
386: break;
387: } else {
1.103 millert 388: fatal("Too high debugging level.");
1.66 markus 389: }
390: /* fallthrough */
1.31 markus 391: case 'V':
1.96 deraadt 392: fprintf(stderr,
393: "%s, SSH protocols %d.%d/%d.%d, OpenSSL 0x%8.8lx\n",
1.46 markus 394: SSH_VERSION,
395: PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
1.96 deraadt 396: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2,
397: SSLeay());
1.31 markus 398: if (opt == 'V')
399: exit(0);
400: break;
401: case 'q':
402: options.log_level = SYSLOG_LEVEL_QUIET;
403: break;
404: case 'e':
405: if (optarg[0] == '^' && optarg[2] == 0 &&
1.78 markus 406: (u_char) optarg[1] >= 64 && (u_char) optarg[1] < 128)
407: options.escape_char = (u_char) optarg[1] & 31;
1.31 markus 408: else if (strlen(optarg) == 1)
1.78 markus 409: options.escape_char = (u_char) optarg[0];
1.31 markus 410: else if (strcmp(optarg, "none") == 0)
411: options.escape_char = -2;
412: else {
413: fprintf(stderr, "Bad escape character '%s'.\n", optarg);
414: exit(1);
415: }
416: break;
417: case 'c':
1.49 markus 418: if (ciphers_valid(optarg)) {
419: /* SSH2 only */
420: options.ciphers = xstrdup(optarg);
1.51 markus 421: options.cipher = SSH_CIPHER_ILLEGAL;
1.49 markus 422: } else {
423: /* SSH1 only */
1.74 markus 424: options.cipher = cipher_number(optarg);
425: if (options.cipher == -1) {
1.49 markus 426: fprintf(stderr, "Unknown cipher type '%s'\n", optarg);
427: exit(1);
428: }
1.74 markus 429: if (options.cipher == SSH_CIPHER_3DES) {
430: options.ciphers = "3des-cbc";
431: } else if (options.cipher == SSH_CIPHER_BLOWFISH) {
432: options.ciphers = "blowfish-cbc";
433: } else {
434: options.ciphers = (char *)-1;
435: }
1.95 markus 436: }
437: break;
438: case 'm':
439: if (mac_valid(optarg))
440: options.macs = xstrdup(optarg);
441: else {
442: fprintf(stderr, "Unknown mac type '%s'\n", optarg);
443: exit(1);
1.31 markus 444: }
445: break;
446: case 'p':
1.113 stevesk 447: options.port = a2port(optarg);
448: if (options.port == 0) {
1.109 markus 449: fprintf(stderr, "Bad port '%s'\n", optarg);
450: exit(1);
451: }
1.31 markus 452: break;
453: case 'l':
454: options.user = optarg;
455: break;
456: case 'R':
1.37 markus 457: if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
458: &fwd_host_port) != 3 &&
459: sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
460: &fwd_host_port) != 3) {
1.31 markus 461: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
462: usage();
463: /* NOTREACHED */
464: }
465: add_remote_forward(&options, fwd_port, buf, fwd_host_port);
466: break;
467: case 'L':
1.37 markus 468: if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
469: &fwd_host_port) != 3 &&
470: sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
471: &fwd_host_port) != 3) {
1.31 markus 472: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
473: usage();
474: /* NOTREACHED */
475: }
476: add_local_forward(&options, fwd_port, buf, fwd_host_port);
477: break;
1.108 markus 478:
479: case 'D':
1.113 stevesk 480: fwd_port = a2port(optarg);
481: if (fwd_port == 0) {
482: fprintf(stderr, "Bad dynamic port '%s'\n", optarg);
1.109 markus 483: exit(1);
484: }
1.108 markus 485: add_local_forward(&options, fwd_port, "socks4", 0);
486: break;
487:
1.31 markus 488: case 'C':
489: options.compression = 1;
490: break;
1.45 markus 491: case 'N':
492: no_shell_flag = 1;
493: no_tty_flag = 1;
494: break;
495: case 'T':
496: no_tty_flag = 1;
497: break;
1.31 markus 498: case 'o':
499: dummy = 1;
500: if (process_config_line(&options, host ? host : "", optarg,
501: "command-line", 0, &dummy) != 0)
502: exit(1);
503: break;
1.85 djm 504: case 's':
505: subsystem_flag = 1;
506: break;
1.31 markus 507: default:
508: usage();
1.1 deraadt 509: }
1.31 markus 510: }
511:
512: /* Check that we got a host name. */
513: if (!host)
514: usage();
515:
1.54 markus 516: SSLeay_add_all_algorithms();
1.72 markus 517: ERR_load_crypto_strings();
1.31 markus 518:
519: /* Initialize the command to execute on remote host. */
520: buffer_init(&command);
1.1 deraadt 521:
1.33 markus 522: /*
523: * Save the command to execute on the remote host in a buffer. There
524: * is no limit on the length of the command, except by the maximum
525: * packet size. Also sets the tty flag if there is no command.
526: */
1.31 markus 527: if (optind == ac) {
528: /* No command specified - execute shell on a tty. */
529: tty_flag = 1;
1.85 djm 530: if (subsystem_flag) {
1.114 stevesk 531: fprintf(stderr, "You must specify a subsystem to invoke.\n");
1.85 djm 532: usage();
533: }
1.31 markus 534: } else {
535: /* A command has been specified. Store it into the
536: buffer. */
537: for (i = optind; i < ac; i++) {
538: if (i > optind)
539: buffer_append(&command, " ", 1);
540: buffer_append(&command, av[i], strlen(av[i]));
541: }
542: }
543:
544: /* Cannot fork to background if no command. */
1.63 markus 545: if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
1.31 markus 546: fatal("Cannot fork into background without a command to execute.");
547:
548: /* Allocate a tty by default if no command specified. */
549: if (buffer_len(&command) == 0)
550: tty_flag = 1;
551:
1.75 markus 552: /* Force no tty*/
553: if (no_tty_flag)
554: tty_flag = 0;
1.31 markus 555: /* Do not allocate a tty if stdin is not a tty. */
1.79 markus 556: if (!isatty(fileno(stdin)) && !force_tty_flag) {
1.31 markus 557: if (tty_flag)
1.103 millert 558: log("Pseudo-terminal will not be allocated because stdin is not a terminal.");
1.31 markus 559: tty_flag = 0;
560: }
1.45 markus 561:
1.101 markus 562: /*
563: * Initialize "log" output. Since we are the client all output
564: * actually goes to stderr.
565: */
1.111 markus 566: log_init(av[0], options.log_level == -1 ? SYSLOG_LEVEL_INFO : options.log_level,
567: SYSLOG_FACILITY_USER, 1);
1.31 markus 568:
569: /* Read per-user configuration file. */
1.83 markus 570: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, _PATH_SSH_USER_CONFFILE);
1.31 markus 571: read_config_file(buf, host, &options);
572:
573: /* Read systemwide configuration file. */
1.83 markus 574: read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
1.31 markus 575:
576: /* Fill configuration defaults. */
577: fill_default_options(&options);
578:
579: /* reinit */
1.101 markus 580: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 1);
1.31 markus 581:
582: if (options.user == NULL)
583: options.user = xstrdup(pw->pw_name);
584:
585: if (options.hostname != NULL)
586: host = options.hostname;
587:
588: /* Disable rhosts authentication if not running as root. */
589: if (original_effective_uid != 0 || !options.use_privileged_port) {
1.77 markus 590: debug("Rhosts Authentication disabled, "
1.71 markus 591: "originating port will not be trusted.");
1.31 markus 592: options.rhosts_authentication = 0;
593: }
1.33 markus 594: /*
595: * If using rsh has been selected, exec it now (without trying
596: * anything else). Note that we must release privileges first.
597: */
1.31 markus 598: if (options.use_rsh) {
1.33 markus 599: /*
600: * Restore our superuser privileges. This must be done
601: * before permanently setting the uid.
602: */
1.31 markus 603: restore_uid();
604:
605: /* Switch to the original uid permanently. */
1.107 markus 606: permanently_set_uid(pw);
1.31 markus 607:
608: /* Execute rsh. */
609: rsh_connect(host, options.user, &command);
610: fatal("rsh_connect returned");
611: }
612: /* Restore our superuser privileges. */
613: restore_uid();
614:
1.77 markus 615: /* Open a connection to the remote host. */
1.31 markus 616:
617: ok = ssh_connect(host, &hostaddr, options.port,
1.77 markus 618: options.connection_attempts,
619: original_effective_uid != 0 || !options.use_privileged_port,
1.107 markus 620: pw, options.proxy_command);
1.31 markus 621:
1.33 markus 622: /*
623: * If we successfully made the connection, load the host private key
624: * in case we will need it later for combined rsa-rhosts
625: * authentication. This must be done before releasing extra
626: * privileges, because the file is only readable by root.
627: */
1.112 markus 628: sensitive_data.nkeys = 0;
629: sensitive_data.keys = NULL;
630: if (ok && (options.rhosts_rsa_authentication ||
631: options.hostbased_authentication)) {
632: sensitive_data.nkeys = 3;
633: sensitive_data.keys = xmalloc(sensitive_data.nkeys*sizeof(Key));
634: sensitive_data.keys[0] = key_load_private_type(KEY_RSA1,
1.105 markus 635: _PATH_HOST_KEY_FILE, "", NULL);
1.112 markus 636: sensitive_data.keys[1] = key_load_private_type(KEY_DSA,
637: _PATH_HOST_DSA_KEY_FILE, "", NULL);
638: sensitive_data.keys[2] = key_load_private_type(KEY_RSA,
639: _PATH_HOST_RSA_KEY_FILE, "", NULL);
1.31 markus 640: }
1.33 markus 641: /*
642: * Get rid of any extra privileges that we may have. We will no
643: * longer need them. Also, extra privileges could make it very hard
644: * to read identity files and other non-world-readable files from the
645: * user's home directory if it happens to be on a NFS volume where
646: * root is mapped to nobody.
647: */
648:
649: /*
650: * Note that some legacy systems need to postpone the following call
651: * to permanently_set_uid() until the private hostkey is destroyed
652: * with RSA_free(). Otherwise the calling user could ptrace() the
653: * process, read the private hostkey and impersonate the host.
654: * OpenBSD does not allow ptracing of setuid processes.
655: */
1.107 markus 656: permanently_set_uid(pw);
1.31 markus 657:
1.33 markus 658: /*
659: * Now that we are back to our own permissions, create ~/.ssh
660: * directory if it doesn\'t already exist.
661: */
1.83 markus 662: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, _PATH_SSH_USER_DIR);
1.31 markus 663: if (stat(buf, &st) < 0)
1.57 djm 664: if (mkdir(buf, 0700) < 0)
1.31 markus 665: error("Could not create directory '%.200s'.", buf);
666:
667: /* Check if the connection failed, and try "rsh" if appropriate. */
668: if (!ok) {
669: if (options.port != 0)
1.35 markus 670: log("Secure connection to %.100s on port %hu refused%.100s.",
1.31 markus 671: host, options.port,
672: options.fallback_to_rsh ? "; reverting to insecure method" : "");
673: else
674: log("Secure connection to %.100s refused%.100s.", host,
675: options.fallback_to_rsh ? "; reverting to insecure method" : "");
676:
677: if (options.fallback_to_rsh) {
678: rsh_connect(host, options.user, &command);
679: fatal("rsh_connect returned");
680: }
681: exit(1);
682: }
1.104 markus 683: /* load options.identity_files */
684: load_public_identity_files();
685:
686: /* Expand ~ in known host file names. */
687: /* XXX mem-leaks: */
1.72 markus 688: options.system_hostfile =
689: tilde_expand_filename(options.system_hostfile, original_real_uid);
690: options.user_hostfile =
691: tilde_expand_filename(options.user_hostfile, original_real_uid);
692: options.system_hostfile2 =
693: tilde_expand_filename(options.system_hostfile2, original_real_uid);
694: options.user_hostfile2 =
695: tilde_expand_filename(options.user_hostfile2, original_real_uid);
1.31 markus 696:
697: /* Log into the remote system. This never returns if the login fails. */
1.112 markus 698: ssh_login(sensitive_data.keys, sensitive_data.nkeys,
699: host, (struct sockaddr *)&hostaddr, pw);
1.31 markus 700:
1.112 markus 701: /* We no longer need the private host keys. Clear them now. */
702: if (sensitive_data.nkeys != 0) {
703: for (i = 0; i < sensitive_data.nkeys; i++) {
704: if (sensitive_data.keys[i] != NULL) {
705: /* Destroys contents safely */
706: debug3("clear hostkey %d", i);
707: key_free(sensitive_data.keys[i]);
708: sensitive_data.keys[i] = NULL;
709: }
710: }
711: xfree(sensitive_data.keys);
712: }
1.31 markus 713:
1.45 markus 714: exit_status = compat20 ? ssh_session2() : ssh_session();
715: packet_close();
716: return exit_status;
717: }
718:
1.50 markus 719: void
720: x11_get_proto(char *proto, int proto_len, char *data, int data_len)
721: {
722: char line[512];
723: FILE *f;
724: int got_data = 0, i;
725:
1.55 markus 726: if (options.xauth_location) {
727: /* Try to get Xauthority information for the display. */
1.93 itojun 728: snprintf(line, sizeof line, "%.100s list %.200s 2>" _PATH_DEVNULL,
1.55 markus 729: options.xauth_location, getenv("DISPLAY"));
730: f = popen(line, "r");
731: if (f && fgets(line, sizeof(line), f) &&
732: sscanf(line, "%*s %s %s", proto, data) == 2)
733: got_data = 1;
734: if (f)
735: pclose(f);
736: }
1.50 markus 737: /*
738: * If we didn't get authentication data, just make up some
739: * data. The forwarding code will check the validity of the
740: * response anyway, and substitute this data. The X11
741: * server, however, will ignore this fake data and use
742: * whatever authentication mechanisms it was using otherwise
743: * for the local connection.
744: */
745: if (!got_data) {
746: u_int32_t rand = 0;
747:
748: strlcpy(proto, "MIT-MAGIC-COOKIE-1", proto_len);
749: for (i = 0; i < 16; i++) {
750: if (i % 4 == 0)
751: rand = arc4random();
752: snprintf(data + 2 * i, data_len - 2 * i, "%02x", rand & 0xff);
753: rand >>= 8;
754: }
755: }
756: }
757:
1.70 markus 758: void
759: ssh_init_forwarding(void)
760: {
1.86 markus 761: int success = 0;
1.70 markus 762: int i;
1.86 markus 763:
1.70 markus 764: /* Initiate local TCP/IP port forwardings. */
765: for (i = 0; i < options.num_local_forwards; i++) {
766: debug("Connections to local port %d forwarded to remote address %.200s:%d",
767: options.local_forwards[i].port,
768: options.local_forwards[i].host,
769: options.local_forwards[i].host_port);
1.86 markus 770: success += channel_request_local_forwarding(
1.70 markus 771: options.local_forwards[i].port,
772: options.local_forwards[i].host,
773: options.local_forwards[i].host_port,
774: options.gateway_ports);
775: }
1.86 markus 776: if (i > 0 && success == 0)
777: error("Could not request local forwarding.");
1.70 markus 778:
779: /* Initiate remote TCP/IP port forwardings. */
780: for (i = 0; i < options.num_remote_forwards; i++) {
781: debug("Connections to remote port %d forwarded to local address %.200s:%d",
782: options.remote_forwards[i].port,
783: options.remote_forwards[i].host,
784: options.remote_forwards[i].host_port);
785: channel_request_remote_forwarding(
786: options.remote_forwards[i].port,
787: options.remote_forwards[i].host,
788: options.remote_forwards[i].host_port);
789: }
790: }
791:
792: void
793: check_agent_present(void)
794: {
795: if (options.forward_agent) {
796: /* Clear agent forwarding if we don\'t have an agent. */
797: int authfd = ssh_get_authentication_socket();
798: if (authfd < 0)
799: options.forward_agent = 0;
800: else
801: ssh_close_authentication_socket(authfd);
802: }
803: }
804:
1.45 markus 805: int
806: ssh_session(void)
807: {
808: int type;
809: int plen;
810: int interactive = 0;
811: int have_tty = 0;
812: struct winsize ws;
813: char *cp;
814:
1.31 markus 815: /* Enable compression if requested. */
816: if (options.compression) {
817: debug("Requesting compression at level %d.", options.compression_level);
818:
819: if (options.compression_level < 1 || options.compression_level > 9)
820: fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
821:
822: /* Send the request. */
823: packet_start(SSH_CMSG_REQUEST_COMPRESSION);
824: packet_put_int(options.compression_level);
825: packet_send();
826: packet_write_wait();
827: type = packet_read(&plen);
828: if (type == SSH_SMSG_SUCCESS)
829: packet_start_compression(options.compression_level);
830: else if (type == SSH_SMSG_FAILURE)
831: log("Warning: Remote host refused compression.");
832: else
833: packet_disconnect("Protocol error waiting for compression response.");
834: }
835: /* Allocate a pseudo tty if appropriate. */
836: if (tty_flag) {
837: debug("Requesting pty.");
838:
839: /* Start the packet. */
840: packet_start(SSH_CMSG_REQUEST_PTY);
841:
842: /* Store TERM in the packet. There is no limit on the
843: length of the string. */
844: cp = getenv("TERM");
845: if (!cp)
846: cp = "";
847: packet_put_string(cp, strlen(cp));
848:
849: /* Store window size in the packet. */
850: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
851: memset(&ws, 0, sizeof(ws));
852: packet_put_int(ws.ws_row);
853: packet_put_int(ws.ws_col);
854: packet_put_int(ws.ws_xpixel);
855: packet_put_int(ws.ws_ypixel);
856:
857: /* Store tty modes in the packet. */
1.115 stevesk 858: tty_make_modes(fileno(stdin), NULL);
1.31 markus 859:
860: /* Send the packet, and wait for it to leave. */
861: packet_send();
862: packet_write_wait();
863:
864: /* Read response from the server. */
865: type = packet_read(&plen);
1.43 markus 866: if (type == SSH_SMSG_SUCCESS) {
1.31 markus 867: interactive = 1;
1.45 markus 868: have_tty = 1;
1.43 markus 869: } else if (type == SSH_SMSG_FAILURE)
1.31 markus 870: log("Warning: Remote host failed or refused to allocate a pseudo tty.");
871: else
872: packet_disconnect("Protocol error waiting for pty request response.");
873: }
874: /* Request X11 forwarding if enabled and DISPLAY is set. */
875: if (options.forward_x11 && getenv("DISPLAY") != NULL) {
1.50 markus 876: char proto[512], data[512];
877: /* Get reasonable local authentication information. */
878: x11_get_proto(proto, sizeof proto, data, sizeof data);
879: /* Request forwarding with authentication spoofing. */
1.31 markus 880: debug("Requesting X11 forwarding with authentication spoofing.");
1.50 markus 881: x11_request_forwarding_with_spoofing(0, proto, data);
1.31 markus 882:
883: /* Read response from the server. */
884: type = packet_read(&plen);
885: if (type == SSH_SMSG_SUCCESS) {
886: interactive = 1;
1.50 markus 887: } else if (type == SSH_SMSG_FAILURE) {
1.31 markus 888: log("Warning: Remote host denied X11 forwarding.");
1.50 markus 889: } else {
1.31 markus 890: packet_disconnect("Protocol error waiting for X11 forwarding");
1.50 markus 891: }
1.31 markus 892: }
893: /* Tell the packet module whether this is an interactive session. */
1.80 markus 894: packet_set_interactive(interactive);
1.31 markus 895:
896: /* Request authentication agent forwarding if appropriate. */
1.70 markus 897: check_agent_present();
898:
1.31 markus 899: if (options.forward_agent) {
900: debug("Requesting authentication agent forwarding.");
901: auth_request_forwarding();
902:
903: /* Read response from the server. */
904: type = packet_read(&plen);
905: packet_integrity_check(plen, 0, type);
906: if (type != SSH_SMSG_SUCCESS)
907: log("Warning: Remote host denied authentication agent forwarding.");
908: }
909:
1.70 markus 910: /* Initiate port forwardings. */
911: ssh_init_forwarding();
1.34 markus 912:
913: /* If requested, let ssh continue in the background. */
1.48 markus 914: if (fork_after_authentication_flag)
1.34 markus 915: if (daemon(1, 1) < 0)
916: fatal("daemon() failed: %.200s", strerror(errno));
1.31 markus 917:
1.33 markus 918: /*
919: * If a command was specified on the command line, execute the
920: * command now. Otherwise request the server to start a shell.
921: */
1.31 markus 922: if (buffer_len(&command) > 0) {
923: int len = buffer_len(&command);
924: if (len > 900)
925: len = 900;
926: debug("Sending command: %.*s", len, buffer_ptr(&command));
927: packet_start(SSH_CMSG_EXEC_CMD);
928: packet_put_string(buffer_ptr(&command), buffer_len(&command));
929: packet_send();
930: packet_write_wait();
931: } else {
932: debug("Requesting shell.");
933: packet_start(SSH_CMSG_EXEC_SHELL);
934: packet_send();
935: packet_write_wait();
936: }
937:
938: /* Enter the interactive session. */
1.60 markus 939: return client_loop(have_tty, tty_flag ? options.escape_char : -1, 0);
1.45 markus 940: }
941:
942: void
1.89 markus 943: client_subsystem_reply(int type, int plen, void *ctxt)
944: {
945: int id, len;
946:
947: id = packet_get_int();
948: len = buffer_len(&command);
1.100 markus 949: if (len > 900)
950: len = 900;
1.89 markus 951: packet_done();
952: if (type == SSH2_MSG_CHANNEL_FAILURE)
953: fatal("Request for subsystem '%.*s' failed on channel %d",
954: len, buffer_ptr(&command), id);
955: }
956:
957: void
1.70 markus 958: ssh_session2_callback(int id, void *arg)
1.45 markus 959: {
960: int len;
1.80 markus 961: int interactive = 0;
1.115 stevesk 962: struct termios tio;
1.80 markus 963:
1.87 deraadt 964: debug("client_init id %d arg %ld", id, (long)arg);
1.31 markus 965:
1.45 markus 966: if (tty_flag) {
967: struct winsize ws;
968: char *cp;
969: cp = getenv("TERM");
970: if (!cp)
971: cp = "";
972: /* Store window size in the packet. */
973: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
974: memset(&ws, 0, sizeof(ws));
975:
976: channel_request_start(id, "pty-req", 0);
977: packet_put_cstring(cp);
978: packet_put_int(ws.ws_col);
979: packet_put_int(ws.ws_row);
980: packet_put_int(ws.ws_xpixel);
981: packet_put_int(ws.ws_ypixel);
1.115 stevesk 982: tio = get_saved_tio();
983: tty_make_modes(/*ignored*/ 0, &tio);
1.45 markus 984: packet_send();
1.80 markus 985: interactive = 1;
1.45 markus 986: /* XXX wait for reply */
987: }
1.50 markus 988: if (options.forward_x11 &&
989: getenv("DISPLAY") != NULL) {
990: char proto[512], data[512];
991: /* Get reasonable local authentication information. */
992: x11_get_proto(proto, sizeof proto, data, sizeof data);
993: /* Request forwarding with authentication spoofing. */
994: debug("Requesting X11 forwarding with authentication spoofing.");
995: x11_request_forwarding_with_spoofing(id, proto, data);
1.80 markus 996: interactive = 1;
1.50 markus 997: /* XXX wait for reply */
998: }
999:
1.70 markus 1000: check_agent_present();
1001: if (options.forward_agent) {
1002: debug("Requesting authentication agent forwarding.");
1003: channel_request_start(id, "auth-agent-req@openssh.com", 0);
1004: packet_send();
1005: }
1006:
1.45 markus 1007: len = buffer_len(&command);
1008: if (len > 0) {
1009: if (len > 900)
1010: len = 900;
1.85 djm 1011: if (subsystem_flag) {
1012: debug("Sending subsystem: %.*s", len, buffer_ptr(&command));
1.89 markus 1013: channel_request_start(id, "subsystem", /*want reply*/ 1);
1014: /* register callback for reply */
1015: /* XXX we asume that client_loop has already been called */
1016: dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
1017: dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1.85 djm 1018: } else {
1019: debug("Sending command: %.*s", len, buffer_ptr(&command));
1020: channel_request_start(id, "exec", 0);
1021: }
1.100 markus 1022: packet_put_string(buffer_ptr(&command), buffer_len(&command));
1.45 markus 1023: packet_send();
1024: } else {
1025: channel_request(id, "shell", 0);
1026: }
1027: /* channel_callback(id, SSH2_MSG_OPEN_CONFIGMATION, client_init, 0); */
1.90 markus 1028:
1.45 markus 1029: /* register different callback, etc. XXX */
1.80 markus 1030: packet_set_interactive(interactive);
1.45 markus 1031: }
1032:
1033: int
1.106 markus 1034: ssh_session2_command(void)
1.45 markus 1035: {
1.106 markus 1036: int id, window, packetmax;
1.60 markus 1037: int in, out, err;
1038:
1.62 markus 1039: if (stdin_null_flag) {
1.93 itojun 1040: in = open(_PATH_DEVNULL, O_RDONLY);
1.62 markus 1041: } else {
1042: in = dup(STDIN_FILENO);
1043: }
1.60 markus 1044: out = dup(STDOUT_FILENO);
1045: err = dup(STDERR_FILENO);
1.45 markus 1046:
1047: if (in < 0 || out < 0 || err < 0)
1.62 markus 1048: fatal("dup() in/out/err failed");
1.45 markus 1049:
1.69 markus 1050: /* enable nonblocking unless tty */
1051: if (!isatty(in))
1052: set_nonblock(in);
1053: if (!isatty(out))
1054: set_nonblock(out);
1055: if (!isatty(err))
1056: set_nonblock(err);
1057:
1.65 markus 1058: window = CHAN_SES_WINDOW_DEFAULT;
1059: packetmax = CHAN_SES_PACKET_DEFAULT;
1060: if (!tty_flag) {
1.45 markus 1061: window *= 2;
1.65 markus 1062: packetmax *=2;
1.45 markus 1063: }
1064: id = channel_new(
1065: "session", SSH_CHANNEL_OPENING, in, out, err,
1.65 markus 1066: window, packetmax, CHAN_EXTENDED_WRITE,
1.69 markus 1067: xstrdup("client-session"), /*nonblock*/0);
1.45 markus 1068:
1.106 markus 1069: debug("channel_new: %d", id);
1070:
1.45 markus 1071: channel_open(id);
1.70 markus 1072: channel_register_callback(id, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION,
1073: ssh_session2_callback, (void *)0);
1.106 markus 1074:
1075: return id;
1076: }
1077:
1078: int
1079: ssh_session2(void)
1080: {
1081: int id;
1082:
1083: /* XXX should be pre-session */
1084: ssh_init_forwarding();
1085:
1086: id = no_shell_flag ? -1 : ssh_session2_command();
1087:
1088: /* If requested, let ssh continue in the background. */
1089: if (fork_after_authentication_flag)
1090: if (daemon(1, 1) < 0)
1091: fatal("daemon() failed: %.200s", strerror(errno));
1.31 markus 1092:
1.60 markus 1093: return client_loop(tty_flag, tty_flag ? options.escape_char : -1, id);
1.72 markus 1094: }
1095:
1.104 markus 1096: void
1097: load_public_identity_files(void)
1098: {
1099: char *filename;
1100: Key *public;
1101: int i;
1102:
1103: for (i = 0; i < options.num_identity_files; i++) {
1104: filename = tilde_expand_filename(options.identity_files[i],
1105: original_real_uid);
1.105 markus 1106: public = key_load_public(filename, NULL);
1.104 markus 1107: debug("identity file %s type %d", filename,
1108: public ? public->type : -1);
1109: xfree(options.identity_files[i]);
1110: options.identity_files[i] = filename;
1111: options.identity_keys[i] = public;
1112: }
1.1 deraadt 1113: }
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