Annotation of src/usr.bin/ssh/ssh.c, Revision 1.93
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"
1.93 ! itojun 42: RCSID("$OpenBSD: ssh.c,v 1.92 2001/02/06 23:06:21 jakob 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"
1.49 markus 68:
69: extern char *__progname;
1.1 deraadt 70:
1.37 markus 71: /* Flag indicating whether IPv4 or IPv6. This can be set on the command line.
72: Default value is AF_UNSPEC means both IPv4 and IPv6. */
73: int IPv4or6 = AF_UNSPEC;
74:
1.31 markus 75: /* Flag indicating whether debug mode is on. This can be set on the command line. */
1.1 deraadt 76: int debug_flag = 0;
77:
1.46 markus 78: /* Flag indicating whether a tty should be allocated */
1.1 deraadt 79: int tty_flag = 0;
1.79 markus 80: int no_tty_flag = 0;
81: int force_tty_flag = 0;
1.1 deraadt 82:
1.45 markus 83: /* don't exec a shell */
84: int no_shell_flag = 0;
85:
1.33 markus 86: /*
87: * Flag indicating that nothing should be read from stdin. This can be set
88: * on the command line.
89: */
1.1 deraadt 90: int stdin_null_flag = 0;
91:
1.33 markus 92: /*
93: * Flag indicating that ssh should fork after authentication. This is useful
94: * so that the pasphrase can be entered manually, and then ssh goes to the
95: * background.
96: */
1.1 deraadt 97: int fork_after_authentication_flag = 0;
98:
1.33 markus 99: /*
100: * General data structure for command line options and options configurable
101: * in configuration files. See readconf.h.
102: */
1.1 deraadt 103: Options options;
104:
1.33 markus 105: /*
106: * Name of the host we are connecting to. This is the name given on the
107: * command line, or the HostName specified for the user-supplied name in a
108: * configuration file.
109: */
1.1 deraadt 110: char *host;
111:
1.22 provos 112: /* socket address the host resolves to */
1.37 markus 113: struct sockaddr_storage hostaddr;
1.22 provos 114:
1.33 markus 115: /*
116: * Flag to indicate that we have received a window change signal which has
117: * not yet been processed. This will cause a message indicating the new
118: * window size to be sent to the server a little later. This is volatile
119: * because this is updated in a signal handler.
120: */
1.1 deraadt 121: volatile int received_window_change_signal = 0;
122:
123: /* Flag indicating whether we have a valid host private key loaded. */
124: int host_private_key_loaded = 0;
125:
126: /* Host private key. */
1.2 provos 127: RSA *host_private_key = NULL;
1.1 deraadt 128:
1.10 dugsong 129: /* Original real UID. */
130: uid_t original_real_uid;
1.1 deraadt 131:
1.45 markus 132: /* command to be executed */
133: Buffer command;
134:
1.85 djm 135: /* Should we execute a command or invoke a subsystem? */
136: int subsystem_flag = 0;
137:
1.1 deraadt 138: /* Prints a help message to the user. This function never returns. */
139:
1.2 provos 140: void
1.93 ! itojun 141: usage(void)
1.1 deraadt 142: {
1.76 markus 143: fprintf(stderr, "Usage: %s [options] host [command]\n", __progname);
1.31 markus 144: fprintf(stderr, "Options:\n");
145: fprintf(stderr, " -l user Log in using this user name.\n");
1.93 ! itojun 146: fprintf(stderr, " -n Redirect input from " _PATH_DEVNULL ".\n");
1.53 markus 147: fprintf(stderr, " -A Enable authentication agent forwarding.\n");
1.31 markus 148: fprintf(stderr, " -a Disable authentication agent forwarding.\n");
1.9 dugsong 149: #ifdef AFS
1.31 markus 150: fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n");
151: #endif /* AFS */
1.88 stevesk 152: fprintf(stderr, " -X Enable X11 connection forwarding.\n");
1.31 markus 153: fprintf(stderr, " -x Disable X11 connection forwarding.\n");
154: fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n");
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: "
166: "``3des'', "
167: "``blowfish''\n");
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);
225: int guess_identity_file_type(const char *filename);
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;
237: struct passwd *pw, pwcopy;
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: /* If program name is not one of the standard names, use it as host name. */
1.76 markus 279: cp = __progname;
1.59 deraadt 280: if (strcmp(cp, "rsh") && strcmp(cp, "ssh") && strcmp(cp, "rlogin") &&
281: strcmp(cp, "slogin") && strcmp(cp, "remsh"))
1.31 markus 282: host = cp;
283:
284: for (optind = 1; optind < ac; optind++) {
285: if (av[optind][0] != '-') {
286: if (host)
287: break;
288: if ((cp = strchr(av[optind], '@'))) {
1.48 markus 289: if(cp == av[optind])
290: usage();
1.31 markus 291: options.user = av[optind];
292: *cp = '\0';
293: host = ++cp;
294: } else
295: host = av[optind];
296: continue;
297: }
298: opt = av[optind][1];
299: if (!opt)
300: usage();
301: if (strchr("eilcpLRo", opt)) { /* options with arguments */
302: optarg = av[optind] + 2;
303: if (strcmp(optarg, "") == 0) {
304: if (optind >= ac - 1)
305: usage();
306: optarg = av[++optind];
307: }
308: } else {
309: if (av[optind][2])
310: usage();
311: optarg = NULL;
312: }
313: switch (opt) {
1.91 jakob 314: case '1':
315: options.protocol = SSH_PROTO_1;
316: break;
1.47 markus 317: case '2':
318: options.protocol = SSH_PROTO_2;
319: break;
1.37 markus 320: case '4':
321: IPv4or6 = AF_INET;
322: break;
323: case '6':
324: IPv4or6 = AF_INET6;
325: break;
1.31 markus 326: case 'n':
327: stdin_null_flag = 1;
328: break;
329: case 'f':
330: fork_after_authentication_flag = 1;
331: stdin_null_flag = 1;
332: break;
333: case 'x':
334: options.forward_x11 = 0;
335: break;
336: case 'X':
337: options.forward_x11 = 1;
338: break;
339: case 'g':
340: options.gateway_ports = 1;
341: break;
342: case 'P':
343: options.use_privileged_port = 0;
344: break;
345: case 'a':
346: options.forward_agent = 0;
1.53 markus 347: break;
348: case 'A':
349: options.forward_agent = 1;
1.31 markus 350: break;
1.9 dugsong 351: #ifdef AFS
1.31 markus 352: case 'k':
353: options.kerberos_tgt_passing = 0;
354: options.afs_token_passing = 0;
355: break;
1.1 deraadt 356: #endif
1.31 markus 357: case 'i':
358: if (stat(optarg, &st) < 0) {
359: fprintf(stderr, "Warning: Identity file %s does not exist.\n",
1.72 markus 360: optarg);
1.31 markus 361: break;
362: }
363: if (options.num_identity_files >= SSH_MAX_IDENTITY_FILES)
364: fatal("Too many identity files specified (max %d)",
1.72 markus 365: SSH_MAX_IDENTITY_FILES);
366: options.identity_files[options.num_identity_files++] = xstrdup(optarg);
1.31 markus 367: break;
368: case 't':
1.79 markus 369: if (tty_flag)
370: force_tty_flag = 1;
1.31 markus 371: tty_flag = 1;
372: break;
373: case 'v':
1.66 markus 374: if (0 == debug_flag) {
375: debug_flag = 1;
376: options.log_level = SYSLOG_LEVEL_DEBUG1;
377: } else if (options.log_level < SYSLOG_LEVEL_DEBUG3) {
378: options.log_level++;
379: break;
380: } else {
381: fatal("Too high debugging level.\n");
382: }
383: /* fallthrough */
1.31 markus 384: case 'V':
1.46 markus 385: fprintf(stderr, "SSH Version %s, protocol versions %d.%d/%d.%d.\n",
386: SSH_VERSION,
387: PROTOCOL_MAJOR_1, PROTOCOL_MINOR_1,
388: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2);
1.45 markus 389: fprintf(stderr, "Compiled with SSL (0x%8.8lx).\n", SSLeay());
1.31 markus 390: if (opt == 'V')
391: exit(0);
392: break;
393: case 'q':
394: options.log_level = SYSLOG_LEVEL_QUIET;
395: break;
396: case 'e':
397: if (optarg[0] == '^' && optarg[2] == 0 &&
1.78 markus 398: (u_char) optarg[1] >= 64 && (u_char) optarg[1] < 128)
399: options.escape_char = (u_char) optarg[1] & 31;
1.31 markus 400: else if (strlen(optarg) == 1)
1.78 markus 401: options.escape_char = (u_char) optarg[0];
1.31 markus 402: else if (strcmp(optarg, "none") == 0)
403: options.escape_char = -2;
404: else {
405: fprintf(stderr, "Bad escape character '%s'.\n", optarg);
406: exit(1);
407: }
408: break;
409: case 'c':
1.49 markus 410: if (ciphers_valid(optarg)) {
411: /* SSH2 only */
412: options.ciphers = xstrdup(optarg);
1.51 markus 413: options.cipher = SSH_CIPHER_ILLEGAL;
1.49 markus 414: } else {
415: /* SSH1 only */
1.74 markus 416: options.cipher = cipher_number(optarg);
417: if (options.cipher == -1) {
1.49 markus 418: fprintf(stderr, "Unknown cipher type '%s'\n", optarg);
419: exit(1);
420: }
1.74 markus 421: if (options.cipher == SSH_CIPHER_3DES) {
422: options.ciphers = "3des-cbc";
423: } else if (options.cipher == SSH_CIPHER_BLOWFISH) {
424: options.ciphers = "blowfish-cbc";
425: } else {
426: options.ciphers = (char *)-1;
427: }
1.31 markus 428: }
429: break;
430: case 'p':
431: options.port = atoi(optarg);
432: break;
433: case 'l':
434: options.user = optarg;
435: break;
436: case 'R':
1.37 markus 437: if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
438: &fwd_host_port) != 3 &&
439: sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
440: &fwd_host_port) != 3) {
1.31 markus 441: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
442: usage();
443: /* NOTREACHED */
444: }
445: add_remote_forward(&options, fwd_port, buf, fwd_host_port);
446: break;
447: case 'L':
1.37 markus 448: if (sscanf(optarg, "%hu/%255[^/]/%hu", &fwd_port, buf,
449: &fwd_host_port) != 3 &&
450: sscanf(optarg, "%hu:%255[^:]:%hu", &fwd_port, buf,
451: &fwd_host_port) != 3) {
1.31 markus 452: fprintf(stderr, "Bad forwarding specification '%s'.\n", optarg);
453: usage();
454: /* NOTREACHED */
455: }
456: add_local_forward(&options, fwd_port, buf, fwd_host_port);
457: break;
458: case 'C':
459: options.compression = 1;
460: break;
1.45 markus 461: case 'N':
462: no_shell_flag = 1;
463: no_tty_flag = 1;
464: break;
465: case 'T':
466: no_tty_flag = 1;
467: break;
1.31 markus 468: case 'o':
469: dummy = 1;
470: if (process_config_line(&options, host ? host : "", optarg,
471: "command-line", 0, &dummy) != 0)
472: exit(1);
473: break;
1.85 djm 474: case 's':
475: subsystem_flag = 1;
476: break;
1.31 markus 477: default:
478: usage();
1.1 deraadt 479: }
1.31 markus 480: }
481:
482: /* Check that we got a host name. */
483: if (!host)
484: usage();
485:
1.54 markus 486: SSLeay_add_all_algorithms();
1.72 markus 487: ERR_load_crypto_strings();
1.31 markus 488:
489: /* Initialize the command to execute on remote host. */
490: buffer_init(&command);
1.1 deraadt 491:
1.33 markus 492: /*
493: * Save the command to execute on the remote host in a buffer. There
494: * is no limit on the length of the command, except by the maximum
495: * packet size. Also sets the tty flag if there is no command.
496: */
1.31 markus 497: if (optind == ac) {
498: /* No command specified - execute shell on a tty. */
499: tty_flag = 1;
1.85 djm 500: if (subsystem_flag) {
501: fprintf(stderr, "You must specify a subsystem to invoke.");
502: usage();
503: }
1.31 markus 504: } else {
505: /* A command has been specified. Store it into the
506: buffer. */
507: for (i = optind; i < ac; i++) {
508: if (i > optind)
509: buffer_append(&command, " ", 1);
510: buffer_append(&command, av[i], strlen(av[i]));
511: }
512: }
513:
514: /* Cannot fork to background if no command. */
1.63 markus 515: if (fork_after_authentication_flag && buffer_len(&command) == 0 && !no_shell_flag)
1.31 markus 516: fatal("Cannot fork into background without a command to execute.");
517:
518: /* Allocate a tty by default if no command specified. */
519: if (buffer_len(&command) == 0)
520: tty_flag = 1;
521:
1.75 markus 522: /* Force no tty*/
523: if (no_tty_flag)
524: tty_flag = 0;
1.31 markus 525: /* Do not allocate a tty if stdin is not a tty. */
1.79 markus 526: if (!isatty(fileno(stdin)) && !force_tty_flag) {
1.31 markus 527: if (tty_flag)
1.82 markus 528: log("Pseudo-terminal will not be allocated because stdin is not a terminal.\n");
1.31 markus 529: tty_flag = 0;
530: }
1.45 markus 531:
1.31 markus 532: /* Get user data. */
533: pw = getpwuid(original_real_uid);
534: if (!pw) {
1.82 markus 535: log("You don't exist, go away!\n");
1.31 markus 536: exit(1);
537: }
538: /* Take a copy of the returned structure. */
539: memset(&pwcopy, 0, sizeof(pwcopy));
540: pwcopy.pw_name = xstrdup(pw->pw_name);
541: pwcopy.pw_passwd = xstrdup(pw->pw_passwd);
542: pwcopy.pw_uid = pw->pw_uid;
543: pwcopy.pw_gid = pw->pw_gid;
1.61 millert 544: pwcopy.pw_class = xstrdup(pw->pw_class);
1.31 markus 545: pwcopy.pw_dir = xstrdup(pw->pw_dir);
546: pwcopy.pw_shell = xstrdup(pw->pw_shell);
547: pw = &pwcopy;
548:
549: /* Initialize "log" output. Since we are the client all output
550: actually goes to the terminal. */
551: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
552:
553: /* Read per-user configuration file. */
1.83 markus 554: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, _PATH_SSH_USER_CONFFILE);
1.31 markus 555: read_config_file(buf, host, &options);
556:
557: /* Read systemwide configuration file. */
1.83 markus 558: read_config_file(_PATH_HOST_CONFIG_FILE, host, &options);
1.31 markus 559:
560: /* Fill configuration defaults. */
561: fill_default_options(&options);
562:
563: /* reinit */
564: log_init(av[0], options.log_level, SYSLOG_FACILITY_USER, 0);
565:
566: if (options.user == NULL)
567: options.user = xstrdup(pw->pw_name);
568:
569: if (options.hostname != NULL)
570: host = options.hostname;
571:
572: /* Disable rhosts authentication if not running as root. */
573: if (original_effective_uid != 0 || !options.use_privileged_port) {
1.77 markus 574: debug("Rhosts Authentication disabled, "
1.71 markus 575: "originating port will not be trusted.");
1.31 markus 576: options.rhosts_authentication = 0;
577: }
1.33 markus 578: /*
579: * If using rsh has been selected, exec it now (without trying
580: * anything else). Note that we must release privileges first.
581: */
1.31 markus 582: if (options.use_rsh) {
1.33 markus 583: /*
584: * Restore our superuser privileges. This must be done
585: * before permanently setting the uid.
586: */
1.31 markus 587: restore_uid();
588:
589: /* Switch to the original uid permanently. */
590: permanently_set_uid(original_real_uid);
591:
592: /* Execute rsh. */
593: rsh_connect(host, options.user, &command);
594: fatal("rsh_connect returned");
595: }
596: /* Restore our superuser privileges. */
597: restore_uid();
598:
1.77 markus 599: /* Open a connection to the remote host. */
1.31 markus 600:
601: ok = ssh_connect(host, &hostaddr, options.port,
1.77 markus 602: options.connection_attempts,
603: original_effective_uid != 0 || !options.use_privileged_port,
604: original_real_uid,
605: options.proxy_command);
1.31 markus 606:
1.33 markus 607: /*
608: * If we successfully made the connection, load the host private key
609: * in case we will need it later for combined rsa-rhosts
610: * authentication. This must be done before releasing extra
611: * privileges, because the file is only readable by root.
612: */
1.49 markus 613: if (ok && (options.protocol & SSH_PROTO_1)) {
614: Key k;
1.31 markus 615: host_private_key = RSA_new();
1.72 markus 616: k.type = KEY_RSA1;
1.49 markus 617: k.rsa = host_private_key;
1.83 markus 618: if (load_private_key(_PATH_HOST_KEY_FILE, "", &k, NULL))
1.31 markus 619: host_private_key_loaded = 1;
620: }
1.33 markus 621: /*
622: * Get rid of any extra privileges that we may have. We will no
623: * longer need them. Also, extra privileges could make it very hard
624: * to read identity files and other non-world-readable files from the
625: * user's home directory if it happens to be on a NFS volume where
626: * root is mapped to nobody.
627: */
628:
629: /*
630: * Note that some legacy systems need to postpone the following call
631: * to permanently_set_uid() until the private hostkey is destroyed
632: * with RSA_free(). Otherwise the calling user could ptrace() the
633: * process, read the private hostkey and impersonate the host.
634: * OpenBSD does not allow ptracing of setuid processes.
635: */
1.31 markus 636: permanently_set_uid(original_real_uid);
637:
1.33 markus 638: /*
639: * Now that we are back to our own permissions, create ~/.ssh
640: * directory if it doesn\'t already exist.
641: */
1.83 markus 642: snprintf(buf, sizeof buf, "%.100s/%.100s", pw->pw_dir, _PATH_SSH_USER_DIR);
1.31 markus 643: if (stat(buf, &st) < 0)
1.57 djm 644: if (mkdir(buf, 0700) < 0)
1.31 markus 645: error("Could not create directory '%.200s'.", buf);
646:
647: /* Check if the connection failed, and try "rsh" if appropriate. */
648: if (!ok) {
649: if (options.port != 0)
1.35 markus 650: log("Secure connection to %.100s on port %hu refused%.100s.",
1.31 markus 651: host, options.port,
652: options.fallback_to_rsh ? "; reverting to insecure method" : "");
653: else
654: log("Secure connection to %.100s refused%.100s.", host,
655: options.fallback_to_rsh ? "; reverting to insecure method" : "");
656:
657: if (options.fallback_to_rsh) {
658: rsh_connect(host, options.user, &command);
659: fatal("rsh_connect returned");
660: }
661: exit(1);
662: }
1.72 markus 663: /* Expand ~ in options.identity_files, known host file names. */
1.49 markus 664: /* XXX mem-leaks */
1.72 markus 665: for (i = 0; i < options.num_identity_files; i++) {
1.31 markus 666: options.identity_files[i] =
1.72 markus 667: tilde_expand_filename(options.identity_files[i], original_real_uid);
668: options.identity_files_type[i] = guess_identity_file_type(options.identity_files[i]);
669: debug("identity file %s type %d", options.identity_files[i],
670: options.identity_files_type[i]);
671: }
672: options.system_hostfile =
673: tilde_expand_filename(options.system_hostfile, original_real_uid);
674: options.user_hostfile =
675: tilde_expand_filename(options.user_hostfile, original_real_uid);
676: options.system_hostfile2 =
677: tilde_expand_filename(options.system_hostfile2, original_real_uid);
678: options.user_hostfile2 =
679: tilde_expand_filename(options.user_hostfile2, original_real_uid);
1.31 markus 680:
681: /* Log into the remote system. This never returns if the login fails. */
682: ssh_login(host_private_key_loaded, host_private_key,
1.37 markus 683: host, (struct sockaddr *)&hostaddr, original_real_uid);
1.31 markus 684:
685: /* We no longer need the host private key. Clear it now. */
686: if (host_private_key_loaded)
687: RSA_free(host_private_key); /* Destroys contents safely */
688:
1.45 markus 689: exit_status = compat20 ? ssh_session2() : ssh_session();
690: packet_close();
691: return exit_status;
692: }
693:
1.50 markus 694: void
695: x11_get_proto(char *proto, int proto_len, char *data, int data_len)
696: {
697: char line[512];
698: FILE *f;
699: int got_data = 0, i;
700:
1.55 markus 701: if (options.xauth_location) {
702: /* Try to get Xauthority information for the display. */
1.93 ! itojun 703: snprintf(line, sizeof line, "%.100s list %.200s 2>" _PATH_DEVNULL,
1.55 markus 704: options.xauth_location, getenv("DISPLAY"));
705: f = popen(line, "r");
706: if (f && fgets(line, sizeof(line), f) &&
707: sscanf(line, "%*s %s %s", proto, data) == 2)
708: got_data = 1;
709: if (f)
710: pclose(f);
711: }
1.50 markus 712: /*
713: * If we didn't get authentication data, just make up some
714: * data. The forwarding code will check the validity of the
715: * response anyway, and substitute this data. The X11
716: * server, however, will ignore this fake data and use
717: * whatever authentication mechanisms it was using otherwise
718: * for the local connection.
719: */
720: if (!got_data) {
721: u_int32_t rand = 0;
722:
723: strlcpy(proto, "MIT-MAGIC-COOKIE-1", proto_len);
724: for (i = 0; i < 16; i++) {
725: if (i % 4 == 0)
726: rand = arc4random();
727: snprintf(data + 2 * i, data_len - 2 * i, "%02x", rand & 0xff);
728: rand >>= 8;
729: }
730: }
731: }
732:
1.70 markus 733: void
734: ssh_init_forwarding(void)
735: {
1.86 markus 736: int success = 0;
1.70 markus 737: int i;
1.86 markus 738:
1.70 markus 739: /* Initiate local TCP/IP port forwardings. */
740: for (i = 0; i < options.num_local_forwards; i++) {
741: debug("Connections to local port %d forwarded to remote address %.200s:%d",
742: options.local_forwards[i].port,
743: options.local_forwards[i].host,
744: options.local_forwards[i].host_port);
1.86 markus 745: success += channel_request_local_forwarding(
1.70 markus 746: options.local_forwards[i].port,
747: options.local_forwards[i].host,
748: options.local_forwards[i].host_port,
749: options.gateway_ports);
750: }
1.86 markus 751: if (i > 0 && success == 0)
752: error("Could not request local forwarding.");
1.70 markus 753:
754: /* Initiate remote TCP/IP port forwardings. */
755: for (i = 0; i < options.num_remote_forwards; i++) {
756: debug("Connections to remote port %d forwarded to local address %.200s:%d",
757: options.remote_forwards[i].port,
758: options.remote_forwards[i].host,
759: options.remote_forwards[i].host_port);
760: channel_request_remote_forwarding(
761: options.remote_forwards[i].port,
762: options.remote_forwards[i].host,
763: options.remote_forwards[i].host_port);
764: }
765: }
766:
767: void
768: check_agent_present(void)
769: {
770: if (options.forward_agent) {
771: /* Clear agent forwarding if we don\'t have an agent. */
772: int authfd = ssh_get_authentication_socket();
773: if (authfd < 0)
774: options.forward_agent = 0;
775: else
776: ssh_close_authentication_socket(authfd);
777: }
778: }
779:
1.45 markus 780: int
781: ssh_session(void)
782: {
783: int type;
784: int plen;
785: int interactive = 0;
786: int have_tty = 0;
787: struct winsize ws;
788: char *cp;
789:
1.31 markus 790: /* Enable compression if requested. */
791: if (options.compression) {
792: debug("Requesting compression at level %d.", options.compression_level);
793:
794: if (options.compression_level < 1 || options.compression_level > 9)
795: fatal("Compression level must be from 1 (fast) to 9 (slow, best).");
796:
797: /* Send the request. */
798: packet_start(SSH_CMSG_REQUEST_COMPRESSION);
799: packet_put_int(options.compression_level);
800: packet_send();
801: packet_write_wait();
802: type = packet_read(&plen);
803: if (type == SSH_SMSG_SUCCESS)
804: packet_start_compression(options.compression_level);
805: else if (type == SSH_SMSG_FAILURE)
806: log("Warning: Remote host refused compression.");
807: else
808: packet_disconnect("Protocol error waiting for compression response.");
809: }
810: /* Allocate a pseudo tty if appropriate. */
811: if (tty_flag) {
812: debug("Requesting pty.");
813:
814: /* Start the packet. */
815: packet_start(SSH_CMSG_REQUEST_PTY);
816:
817: /* Store TERM in the packet. There is no limit on the
818: length of the string. */
819: cp = getenv("TERM");
820: if (!cp)
821: cp = "";
822: packet_put_string(cp, strlen(cp));
823:
824: /* Store window size in the packet. */
825: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
826: memset(&ws, 0, sizeof(ws));
827: packet_put_int(ws.ws_row);
828: packet_put_int(ws.ws_col);
829: packet_put_int(ws.ws_xpixel);
830: packet_put_int(ws.ws_ypixel);
831:
832: /* Store tty modes in the packet. */
833: tty_make_modes(fileno(stdin));
834:
835: /* Send the packet, and wait for it to leave. */
836: packet_send();
837: packet_write_wait();
838:
839: /* Read response from the server. */
840: type = packet_read(&plen);
1.43 markus 841: if (type == SSH_SMSG_SUCCESS) {
1.31 markus 842: interactive = 1;
1.45 markus 843: have_tty = 1;
1.43 markus 844: } else if (type == SSH_SMSG_FAILURE)
1.31 markus 845: log("Warning: Remote host failed or refused to allocate a pseudo tty.");
846: else
847: packet_disconnect("Protocol error waiting for pty request response.");
848: }
849: /* Request X11 forwarding if enabled and DISPLAY is set. */
850: if (options.forward_x11 && getenv("DISPLAY") != NULL) {
1.50 markus 851: char proto[512], data[512];
852: /* Get reasonable local authentication information. */
853: x11_get_proto(proto, sizeof proto, data, sizeof data);
854: /* Request forwarding with authentication spoofing. */
1.31 markus 855: debug("Requesting X11 forwarding with authentication spoofing.");
1.50 markus 856: x11_request_forwarding_with_spoofing(0, proto, data);
1.31 markus 857:
858: /* Read response from the server. */
859: type = packet_read(&plen);
860: if (type == SSH_SMSG_SUCCESS) {
861: interactive = 1;
1.50 markus 862: } else if (type == SSH_SMSG_FAILURE) {
1.31 markus 863: log("Warning: Remote host denied X11 forwarding.");
1.50 markus 864: } else {
1.31 markus 865: packet_disconnect("Protocol error waiting for X11 forwarding");
1.50 markus 866: }
1.31 markus 867: }
868: /* Tell the packet module whether this is an interactive session. */
1.80 markus 869: packet_set_interactive(interactive);
1.31 markus 870:
871: /* Request authentication agent forwarding if appropriate. */
1.70 markus 872: check_agent_present();
873:
1.31 markus 874: if (options.forward_agent) {
875: debug("Requesting authentication agent forwarding.");
876: auth_request_forwarding();
877:
878: /* Read response from the server. */
879: type = packet_read(&plen);
880: packet_integrity_check(plen, 0, type);
881: if (type != SSH_SMSG_SUCCESS)
882: log("Warning: Remote host denied authentication agent forwarding.");
883: }
884:
1.70 markus 885: /* Initiate port forwardings. */
886: ssh_init_forwarding();
1.34 markus 887:
888: /* If requested, let ssh continue in the background. */
1.48 markus 889: if (fork_after_authentication_flag)
1.34 markus 890: if (daemon(1, 1) < 0)
891: fatal("daemon() failed: %.200s", strerror(errno));
1.31 markus 892:
1.33 markus 893: /*
894: * If a command was specified on the command line, execute the
895: * command now. Otherwise request the server to start a shell.
896: */
1.31 markus 897: if (buffer_len(&command) > 0) {
898: int len = buffer_len(&command);
899: if (len > 900)
900: len = 900;
901: debug("Sending command: %.*s", len, buffer_ptr(&command));
902: packet_start(SSH_CMSG_EXEC_CMD);
903: packet_put_string(buffer_ptr(&command), buffer_len(&command));
904: packet_send();
905: packet_write_wait();
906: } else {
907: debug("Requesting shell.");
908: packet_start(SSH_CMSG_EXEC_SHELL);
909: packet_send();
910: packet_write_wait();
911: }
912:
913: /* Enter the interactive session. */
1.60 markus 914: return client_loop(have_tty, tty_flag ? options.escape_char : -1, 0);
1.45 markus 915: }
916:
917: void
1.89 markus 918: client_subsystem_reply(int type, int plen, void *ctxt)
919: {
920: int id, len;
921:
922: id = packet_get_int();
923: len = buffer_len(&command);
924: len = MAX(len, 900);
925: packet_done();
926: if (type == SSH2_MSG_CHANNEL_FAILURE)
927: fatal("Request for subsystem '%.*s' failed on channel %d",
928: len, buffer_ptr(&command), id);
929: }
930:
931: void
1.70 markus 932: ssh_session2_callback(int id, void *arg)
1.45 markus 933: {
934: int len;
1.80 markus 935: int interactive = 0;
936:
1.87 deraadt 937: debug("client_init id %d arg %ld", id, (long)arg);
1.31 markus 938:
1.45 markus 939: if (no_shell_flag)
940: goto done;
941:
942: if (tty_flag) {
943: struct winsize ws;
944: char *cp;
945: cp = getenv("TERM");
946: if (!cp)
947: cp = "";
948: /* Store window size in the packet. */
949: if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
950: memset(&ws, 0, sizeof(ws));
951:
952: channel_request_start(id, "pty-req", 0);
953: packet_put_cstring(cp);
954: packet_put_int(ws.ws_col);
955: packet_put_int(ws.ws_row);
956: packet_put_int(ws.ws_xpixel);
957: packet_put_int(ws.ws_ypixel);
958: packet_put_cstring(""); /* XXX: encode terminal modes */
959: packet_send();
1.80 markus 960: interactive = 1;
1.45 markus 961: /* XXX wait for reply */
962: }
1.50 markus 963: if (options.forward_x11 &&
964: getenv("DISPLAY") != NULL) {
965: char proto[512], data[512];
966: /* Get reasonable local authentication information. */
967: x11_get_proto(proto, sizeof proto, data, sizeof data);
968: /* Request forwarding with authentication spoofing. */
969: debug("Requesting X11 forwarding with authentication spoofing.");
970: x11_request_forwarding_with_spoofing(id, proto, data);
1.80 markus 971: interactive = 1;
1.50 markus 972: /* XXX wait for reply */
973: }
974:
1.70 markus 975: check_agent_present();
976: if (options.forward_agent) {
977: debug("Requesting authentication agent forwarding.");
978: channel_request_start(id, "auth-agent-req@openssh.com", 0);
979: packet_send();
980: }
981:
1.45 markus 982: len = buffer_len(&command);
983: if (len > 0) {
984: if (len > 900)
985: len = 900;
1.85 djm 986: if (subsystem_flag) {
987: debug("Sending subsystem: %.*s", len, buffer_ptr(&command));
1.89 markus 988: channel_request_start(id, "subsystem", /*want reply*/ 1);
989: /* register callback for reply */
990: /* XXX we asume that client_loop has already been called */
991: dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &client_subsystem_reply);
992: dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &client_subsystem_reply);
1.85 djm 993: } else {
994: debug("Sending command: %.*s", len, buffer_ptr(&command));
995: channel_request_start(id, "exec", 0);
996: }
1.45 markus 997: packet_put_string(buffer_ptr(&command), len);
998: packet_send();
999: } else {
1000: channel_request(id, "shell", 0);
1001: }
1002: /* channel_callback(id, SSH2_MSG_OPEN_CONFIGMATION, client_init, 0); */
1.90 markus 1003:
1.45 markus 1004: done:
1005: /* register different callback, etc. XXX */
1.80 markus 1006: packet_set_interactive(interactive);
1.45 markus 1007: }
1008:
1009: int
1010: ssh_session2(void)
1011: {
1012: int window, packetmax, id;
1.60 markus 1013: int in, out, err;
1014:
1.62 markus 1015: if (stdin_null_flag) {
1.93 ! itojun 1016: in = open(_PATH_DEVNULL, O_RDONLY);
1.62 markus 1017: } else {
1018: in = dup(STDIN_FILENO);
1019: }
1.60 markus 1020: out = dup(STDOUT_FILENO);
1021: err = dup(STDERR_FILENO);
1.45 markus 1022:
1023: if (in < 0 || out < 0 || err < 0)
1.62 markus 1024: fatal("dup() in/out/err failed");
1.45 markus 1025:
1.69 markus 1026: /* enable nonblocking unless tty */
1027: if (!isatty(in))
1028: set_nonblock(in);
1029: if (!isatty(out))
1030: set_nonblock(out);
1031: if (!isatty(err))
1032: set_nonblock(err);
1033:
1.70 markus 1034: /* XXX should be pre-session */
1035: ssh_init_forwarding();
1.88 stevesk 1036:
1.62 markus 1037: /* If requested, let ssh continue in the background. */
1038: if (fork_after_authentication_flag)
1039: if (daemon(1, 1) < 0)
1040: fatal("daemon() failed: %.200s", strerror(errno));
1041:
1.65 markus 1042: window = CHAN_SES_WINDOW_DEFAULT;
1043: packetmax = CHAN_SES_PACKET_DEFAULT;
1044: if (!tty_flag) {
1.45 markus 1045: window *= 2;
1.65 markus 1046: packetmax *=2;
1.45 markus 1047: }
1048: id = channel_new(
1049: "session", SSH_CHANNEL_OPENING, in, out, err,
1.65 markus 1050: window, packetmax, CHAN_EXTENDED_WRITE,
1.69 markus 1051: xstrdup("client-session"), /*nonblock*/0);
1.45 markus 1052:
1053: channel_open(id);
1.70 markus 1054: channel_register_callback(id, SSH2_MSG_CHANNEL_OPEN_CONFIRMATION,
1055: ssh_session2_callback, (void *)0);
1.31 markus 1056:
1.60 markus 1057: return client_loop(tty_flag, tty_flag ? options.escape_char : -1, id);
1.72 markus 1058: }
1059:
1060: int
1061: guess_identity_file_type(const char *filename)
1062: {
1063: struct stat st;
1064: Key *public;
1065: int type = KEY_RSA1; /* default */
1066:
1067: if (stat(filename, &st) < 0) {
1.73 markus 1068: /* ignore this key */
1.72 markus 1069: return KEY_UNSPEC;
1070: }
1071: public = key_new(type);
1072: if (!load_public_key(filename, public, NULL)) {
1073: /* ok, so we will assume this is 'some' key */
1074: type = KEY_UNSPEC;
1075: }
1076: key_free(public);
1077: return type;
1.1 deraadt 1078: }
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