Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.240
1.240 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.239 2013/08/20 00:11:38 djm Exp $ */
1.1 deraadt 2: /*
1.39 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
1.78 deraadt 8: *
9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 14: */
1.1 deraadt 15:
1.174 stevesk 16: #include <sys/types.h>
17: #include <sys/wait.h>
1.175 stevesk 18: #include <sys/stat.h>
1.187 stevesk 19: #include <sys/socket.h>
1.195 stevesk 20: #include <sys/time.h>
1.187 stevesk 21:
22: #include <netinet/in.h>
1.172 stevesk 23:
1.176 stevesk 24: #include <ctype.h>
1.190 stevesk 25: #include <errno.h>
1.216 dtucker 26: #include <fcntl.h>
1.191 stevesk 27: #include <netdb.h>
1.172 stevesk 28: #include <paths.h>
1.199 deraadt 29: #include <signal.h>
1.188 stevesk 30: #include <pwd.h>
1.198 stevesk 31: #include <stdio.h>
1.196 stevesk 32: #include <stdlib.h>
1.193 stevesk 33: #include <string.h>
1.192 stevesk 34: #include <unistd.h>
1.71 markus 35:
1.199 deraadt 36: #include "xmalloc.h"
1.91 markus 37: #include "ssh.h"
1.1 deraadt 38: #include "rsa.h"
1.59 markus 39: #include "buffer.h"
1.1 deraadt 40: #include "packet.h"
41: #include "uidswap.h"
1.21 markus 42: #include "compat.h"
1.58 markus 43: #include "key.h"
1.71 markus 44: #include "sshconnect.h"
1.58 markus 45: #include "hostfile.h"
1.91 markus 46: #include "log.h"
47: #include "readconf.h"
48: #include "atomicio.h"
49: #include "misc.h"
1.140 jakob 50: #include "dns.h"
1.214 andreas 51: #include "roaming.h"
1.239 djm 52: #include "monitor_fdpass.h"
1.219 djm 53: #include "ssh2.h"
1.186 stevesk 54: #include "version.h"
1.140 jakob 55:
1.70 markus 56: char *client_version_string = NULL;
57: char *server_version_string = NULL;
1.59 markus 58:
1.169 stevesk 59: static int matching_host_key_dns = 0;
1.145 jakob 60:
1.227 djm 61: static pid_t proxy_command_pid = 0;
62:
1.124 markus 63: /* import */
1.43 markus 64: extern Options options;
1.50 markus 65: extern char *__progname;
1.124 markus 66: extern uid_t original_real_uid;
67: extern uid_t original_effective_uid;
1.91 markus 68:
1.229 djm 69: static int show_other_keys(struct hostkeys *, Key *);
1.150 jakob 70: static void warn_changed_key(Key *);
1.132 markus 71:
1.239 djm 72: /* Expand a proxy command */
73: static char *
74: expand_proxy_command(const char *proxy_command, const char *user,
75: const char *host, int port)
76: {
77: char *tmp, *ret, strport[NI_MAXSERV];
78:
79: snprintf(strport, sizeof strport, "%hu", port);
80: xasprintf(&tmp, "exec %s", proxy_command);
81: ret = percent_expand(tmp, "h", host, "p", strport,
82: "r", options.user, (char *)NULL);
83: free(tmp);
84: return ret;
85: }
86:
87: /*
88: * Connect to the given ssh server using a proxy command that passes a
89: * a connected fd back to us.
90: */
91: static int
92: ssh_proxy_fdpass_connect(const char *host, u_short port,
93: const char *proxy_command)
94: {
95: char *command_string;
96: int sp[2], sock;
97: pid_t pid;
98: char *shell;
99:
100: if ((shell = getenv("SHELL")) == NULL)
101: shell = _PATH_BSHELL;
102:
103: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
104: fatal("Could not create socketpair to communicate with "
105: "proxy dialer: %.100s", strerror(errno));
106:
107: command_string = expand_proxy_command(proxy_command, options.user,
108: host, port);
109: debug("Executing proxy dialer command: %.500s", command_string);
110:
111: /* Fork and execute the proxy command. */
112: if ((pid = fork()) == 0) {
113: char *argv[10];
114:
115: /* Child. Permanently give up superuser privileges. */
116: permanently_drop_suid(original_real_uid);
117:
118: close(sp[1]);
119: /* Redirect stdin and stdout. */
120: if (sp[0] != 0) {
121: if (dup2(sp[0], 0) < 0)
122: perror("dup2 stdin");
123: }
124: if (sp[0] != 1) {
125: if (dup2(sp[0], 1) < 0)
126: perror("dup2 stdout");
127: }
128: if (sp[0] >= 2)
129: close(sp[0]);
130:
131: /*
132: * Stderr is left as it is so that error messages get
133: * printed on the user's terminal.
134: */
135: argv[0] = shell;
136: argv[1] = "-c";
137: argv[2] = command_string;
138: argv[3] = NULL;
139:
140: /*
141: * Execute the proxy command.
142: * Note that we gave up any extra privileges above.
143: */
144: execv(argv[0], argv);
145: perror(argv[0]);
146: exit(1);
147: }
148: /* Parent. */
149: if (pid < 0)
150: fatal("fork failed: %.100s", strerror(errno));
151: close(sp[0]);
152: free(command_string);
153:
154: if ((sock = mm_receive_fd(sp[1])) == -1)
155: fatal("proxy dialer did not pass back a connection");
156:
157: while (waitpid(pid, NULL, 0) == -1)
158: if (errno != EINTR)
159: fatal("Couldn't wait for child: %s", strerror(errno));
160:
161: /* Set the connection file descriptors. */
162: packet_set_connection(sock, sock);
163: packet_set_timeout(options.server_alive_interval,
164: options.server_alive_count_max);
165:
166: return 0;
167: }
168:
1.39 deraadt 169: /*
170: * Connect to the given ssh server using a proxy command.
171: */
1.109 itojun 172: static int
1.124 markus 173: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 174: {
1.239 djm 175: char *command_string;
1.38 markus 176: int pin[2], pout[2];
1.69 deraadt 177: pid_t pid;
1.239 djm 178: char *shell;
1.237 markus 179:
180: if (!strcmp(proxy_command, "-")) {
181: packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
182: packet_set_timeout(options.server_alive_interval,
183: options.server_alive_count_max);
184: return 0;
185: }
1.201 djm 186:
1.239 djm 187: if (options.proxy_use_fdpass)
188: return ssh_proxy_fdpass_connect(host, port, proxy_command);
189:
1.226 djm 190: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 191: shell = _PATH_BSHELL;
1.38 markus 192:
193: /* Create pipes for communicating with the proxy. */
194: if (pipe(pin) < 0 || pipe(pout) < 0)
195: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 196: strerror(errno));
1.38 markus 197:
1.239 djm 198: command_string = expand_proxy_command(proxy_command, options.user,
199: host, port);
1.38 markus 200: debug("Executing proxy command: %.500s", command_string);
201:
202: /* Fork and execute the proxy command. */
203: if ((pid = fork()) == 0) {
204: char *argv[10];
205:
206: /* Child. Permanently give up superuser privileges. */
1.184 markus 207: permanently_drop_suid(original_real_uid);
1.38 markus 208:
209: /* Redirect stdin and stdout. */
210: close(pin[1]);
211: if (pin[0] != 0) {
212: if (dup2(pin[0], 0) < 0)
213: perror("dup2 stdin");
214: close(pin[0]);
215: }
216: close(pout[0]);
217: if (dup2(pout[1], 1) < 0)
218: perror("dup2 stdout");
219: /* Cannot be 1 because pin allocated two descriptors. */
220: close(pout[1]);
221:
222: /* Stderr is left as it is so that error messages get
223: printed on the user's terminal. */
1.201 djm 224: argv[0] = shell;
1.38 markus 225: argv[1] = "-c";
226: argv[2] = command_string;
227: argv[3] = NULL;
228:
229: /* Execute the proxy command. Note that we gave up any
230: extra privileges above. */
1.232 djm 231: signal(SIGPIPE, SIG_DFL);
1.89 markus 232: execv(argv[0], argv);
233: perror(argv[0]);
1.38 markus 234: exit(1);
235: }
236: /* Parent. */
237: if (pid < 0)
238: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 239: else
240: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 241:
242: /* Close child side of the descriptors. */
243: close(pin[0]);
244: close(pout[1]);
245:
246: /* Free the command name. */
1.238 djm 247: free(command_string);
1.38 markus 248:
249: /* Set the connection file descriptors. */
250: packet_set_connection(pout[0], pin[1]);
1.207 dtucker 251: packet_set_timeout(options.server_alive_interval,
252: options.server_alive_count_max);
1.1 deraadt 253:
1.110 markus 254: /* Indicate OK return */
255: return 0;
1.227 djm 256: }
257:
258: void
259: ssh_kill_proxy_command(void)
260: {
261: /*
262: * Send SIGHUP to proxy command if used. We don't wait() in
263: * case it hangs and instead rely on init to reap the child
264: */
265: if (proxy_command_pid > 1)
1.228 djm 266: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 267: }
268:
1.39 deraadt 269: /*
270: * Creates a (possibly privileged) socket for use as the ssh connection.
271: */
1.109 itojun 272: static int
1.139 markus 273: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 274: {
1.240 ! djm 275: int sock, r, gaierr;
1.105 markus 276: struct addrinfo hints, *res;
1.1 deraadt 277:
1.217 dtucker 278: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 279: if (sock < 0) {
1.240 ! djm 280: error("socket: %s", strerror(errno));
1.216 dtucker 281: return -1;
282: }
283: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 284:
285: /* Bind the socket to an alternative local IP address */
1.240 ! djm 286: if (options.bind_address == NULL && !privileged)
1.105 markus 287: return sock;
288:
289: memset(&hints, 0, sizeof(hints));
1.139 markus 290: hints.ai_family = ai->ai_family;
291: hints.ai_socktype = ai->ai_socktype;
292: hints.ai_protocol = ai->ai_protocol;
1.105 markus 293: hints.ai_flags = AI_PASSIVE;
1.205 dtucker 294: gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
1.105 markus 295: if (gaierr) {
296: error("getaddrinfo: %s: %s", options.bind_address,
1.203 dtucker 297: ssh_gai_strerror(gaierr));
1.105 markus 298: close(sock);
299: return -1;
300: }
1.240 ! djm 301: /*
! 302: * If we are running as root and want to connect to a privileged
! 303: * port, bind our own socket to a privileged port.
! 304: */
! 305: if (privileged) {
! 306: PRIV_START;
! 307: r = bindresvport_sa(sock, res->ai_addr);
! 308: PRIV_END;
! 309: if (r < 0) {
! 310: error("bindresvport_sa: af=%d %s", ai->ai_family,
! 311: strerror(errno));
! 312: goto fail;
! 313: }
! 314: } else {
! 315: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
! 316: error("bind: %s: %s", options.bind_address,
! 317: strerror(errno));
! 318: fail:
! 319: close(sock);
! 320: freeaddrinfo(res);
! 321: return -1;
! 322: }
1.38 markus 323: }
1.105 markus 324: freeaddrinfo(res);
1.38 markus 325: return sock;
1.1 deraadt 326: }
327:
1.141 djm 328: static int
329: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 330: socklen_t addrlen, int *timeoutp)
1.141 djm 331: {
332: fd_set *fdset;
1.202 djm 333: struct timeval tv, t_start;
1.141 djm 334: socklen_t optlen;
1.179 djm 335: int optval, rc, result = -1;
1.141 djm 336:
1.202 djm 337: gettimeofday(&t_start, NULL);
338:
339: if (*timeoutp <= 0) {
340: result = connect(sockfd, serv_addr, addrlen);
341: goto done;
342: }
1.141 djm 343:
1.156 djm 344: set_nonblock(sockfd);
1.141 djm 345: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 346: if (rc == 0) {
347: unset_nonblock(sockfd);
1.202 djm 348: result = 0;
349: goto done;
350: }
351: if (errno != EINPROGRESS) {
352: result = -1;
353: goto done;
1.156 djm 354: }
1.141 djm 355:
1.179 djm 356: fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
357: sizeof(fd_mask));
1.141 djm 358: FD_SET(sockfd, fdset);
1.202 djm 359: ms_to_timeval(&tv, *timeoutp);
1.141 djm 360:
1.162 deraadt 361: for (;;) {
1.141 djm 362: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
363: if (rc != -1 || errno != EINTR)
364: break;
365: }
366:
1.162 deraadt 367: switch (rc) {
1.141 djm 368: case 0:
369: /* Timed out */
370: errno = ETIMEDOUT;
1.142 djm 371: break;
1.141 djm 372: case -1:
373: /* Select error */
1.154 djm 374: debug("select: %s", strerror(errno));
1.142 djm 375: break;
1.141 djm 376: case 1:
377: /* Completed or failed */
378: optval = 0;
379: optlen = sizeof(optval);
1.154 djm 380: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 381: &optlen) == -1) {
1.154 djm 382: debug("getsockopt: %s", strerror(errno));
1.142 djm 383: break;
1.148 markus 384: }
1.141 djm 385: if (optval != 0) {
386: errno = optval;
1.142 djm 387: break;
1.141 djm 388: }
1.142 djm 389: result = 0;
1.156 djm 390: unset_nonblock(sockfd);
1.141 djm 391: break;
392: default:
393: /* Should not occur */
394: fatal("Bogus return (%d) from select()", rc);
395: }
396:
1.238 djm 397: free(fdset);
1.202 djm 398:
399: done:
400: if (result == 0 && *timeoutp > 0) {
401: ms_subtract_diff(&t_start, timeoutp);
402: if (*timeoutp <= 0) {
403: errno = ETIMEDOUT;
404: result = -1;
405: }
406: }
407:
1.142 djm 408: return (result);
1.141 djm 409: }
410:
1.39 deraadt 411: /*
1.49 markus 412: * Opens a TCP/IP connection to the remote server on the given host.
413: * The address of the remote host will be returned in hostaddr.
1.124 markus 414: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 415: * a privileged port will be allocated to make the connection.
1.124 markus 416: * This requires super-user privileges if needpriv is true.
1.39 deraadt 417: * Connection_attempts specifies the maximum number of tries (one per
418: * second). If proxy_command is non-NULL, it specifies the command (with %h
419: * and %p substituted for host and port, respectively) to use to contact
420: * the daemon.
421: */
1.38 markus 422: int
1.49 markus 423: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.202 djm 424: u_short port, int family, int connection_attempts, int *timeout_ms,
425: int want_keepalive, int needpriv, const char *proxy_command)
1.1 deraadt 426: {
1.90 markus 427: int gaierr;
428: int on = 1;
1.49 markus 429: int sock = -1, attempt;
1.90 markus 430: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 431: struct addrinfo hints, *ai, *aitop;
1.38 markus 432:
1.136 markus 433: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 434:
435: /* If a proxy command is given, connect using it. */
436: if (proxy_command != NULL)
1.124 markus 437: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 438:
439: /* No proxy command. */
440:
1.49 markus 441: memset(&hints, 0, sizeof(hints));
1.115 markus 442: hints.ai_family = family;
1.49 markus 443: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 444: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 445: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.203 dtucker 446: fatal("%s: Could not resolve hostname %.100s: %s", __progname,
447: host, ssh_gai_strerror(gaierr));
1.38 markus 448:
1.181 markus 449: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 450: if (attempt > 0) {
451: /* Sleep a moment before retrying. */
452: sleep(1);
1.38 markus 453: debug("Trying again...");
1.200 markus 454: }
1.181 markus 455: /*
456: * Loop through addresses for this host, and try each one in
457: * sequence until the connection succeeds.
458: */
1.49 markus 459: for (ai = aitop; ai; ai = ai->ai_next) {
460: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
461: continue;
462: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
463: ntop, sizeof(ntop), strport, sizeof(strport),
464: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
465: error("ssh_connect: getnameinfo failed");
466: continue;
467: }
468: debug("Connecting to %.200s [%.100s] port %s.",
469: host, ntop, strport);
470:
471: /* Create a socket for connecting. */
1.139 markus 472: sock = ssh_create_socket(needpriv, ai);
1.49 markus 473: if (sock < 0)
1.110 markus 474: /* Any error is already output */
1.49 markus 475: continue;
476:
1.141 djm 477: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 478: timeout_ms) >= 0) {
1.49 markus 479: /* Successful connection. */
1.102 markus 480: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 481: break;
1.49 markus 482: } else {
1.131 itojun 483: debug("connect to address %s port %s: %s",
484: ntop, strport, strerror(errno));
1.38 markus 485: close(sock);
1.181 markus 486: sock = -1;
1.38 markus 487: }
488: }
1.181 markus 489: if (sock != -1)
1.49 markus 490: break; /* Successful connection. */
1.38 markus 491: }
1.49 markus 492:
493: freeaddrinfo(aitop);
494:
1.38 markus 495: /* Return failure if we didn't get a successful connection. */
1.181 markus 496: if (sock == -1) {
1.159 markus 497: error("ssh: connect to host %s port %s: %s",
1.130 itojun 498: host, strport, strerror(errno));
1.159 markus 499: return (-1);
1.130 itojun 500: }
1.38 markus 501:
502: debug("Connection established.");
1.90 markus 503:
1.155 markus 504: /* Set SO_KEEPALIVE if requested. */
1.202 djm 505: if (want_keepalive &&
1.90 markus 506: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
507: sizeof(on)) < 0)
508: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 509:
510: /* Set the connection. */
511: packet_set_connection(sock, sock);
1.207 dtucker 512: packet_set_timeout(options.server_alive_interval,
513: options.server_alive_count_max);
1.1 deraadt 514:
1.110 markus 515: return 0;
1.59 markus 516: }
517:
1.235 djm 518: static void
519: send_client_banner(int connection_out, int minor1)
520: {
521: /* Send our own protocol version identification. */
522: if (compat20) {
523: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
524: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
525: } else {
526: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n",
527: PROTOCOL_MAJOR_1, minor1, SSH_VERSION);
528: }
529: if (roaming_atomicio(vwrite, connection_out, client_version_string,
530: strlen(client_version_string)) != strlen(client_version_string))
531: fatal("write: %.100s", strerror(errno));
532: chop(client_version_string);
533: debug("Local version string %.100s", client_version_string);
534: }
535:
1.43 markus 536: /*
1.39 deraadt 537: * Waits for the server identification string, and sends our own
538: * identification string.
539: */
1.213 andreas 540: void
1.202 djm 541: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 542: {
1.38 markus 543: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 544: int remote_major, remote_minor, mismatch;
1.38 markus 545: int connection_in = packet_get_connection_in();
546: int connection_out = packet_get_connection_out();
1.235 djm 547: int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
1.185 djm 548: u_int i, n;
1.202 djm 549: size_t len;
550: int fdsetsz, remaining, rc;
551: struct timeval t_start, t_remaining;
552: fd_set *fdset;
553:
554: fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
555: fdset = xcalloc(1, fdsetsz);
1.38 markus 556:
1.235 djm 557: /*
558: * If we are SSH2-only then we can send the banner immediately and
559: * save a round-trip.
560: */
561: if (options.protocol == SSH_PROTO_2) {
562: enable_compat20();
563: send_client_banner(connection_out, 0);
564: client_banner_sent = 1;
565: }
566:
1.163 avsm 567: /* Read other side's version identification. */
1.202 djm 568: remaining = timeout_ms;
1.185 djm 569: for (n = 0;;) {
1.75 markus 570: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 571: if (timeout_ms > 0) {
572: gettimeofday(&t_start, NULL);
573: ms_to_timeval(&t_remaining, remaining);
574: FD_SET(connection_in, fdset);
575: rc = select(connection_in + 1, fdset, NULL,
576: fdset, &t_remaining);
577: ms_subtract_diff(&t_start, &remaining);
578: if (rc == 0 || remaining <= 0)
579: fatal("Connection timed out during "
580: "banner exchange");
581: if (rc == -1) {
582: if (errno == EINTR)
583: continue;
584: fatal("ssh_exchange_identification: "
585: "select: %s", strerror(errno));
586: }
587: }
588:
1.214 andreas 589: len = roaming_atomicio(read, connection_in, &buf[i], 1);
1.163 avsm 590:
1.167 djm 591: if (len != 1 && errno == EPIPE)
1.202 djm 592: fatal("ssh_exchange_identification: "
593: "Connection closed by remote host");
1.163 avsm 594: else if (len != 1)
1.202 djm 595: fatal("ssh_exchange_identification: "
596: "read: %.100s", strerror(errno));
1.75 markus 597: if (buf[i] == '\r') {
598: buf[i] = '\n';
599: buf[i + 1] = 0;
600: continue; /**XXX wait for \n */
601: }
602: if (buf[i] == '\n') {
603: buf[i + 1] = 0;
604: break;
605: }
1.185 djm 606: if (++n > 65536)
1.202 djm 607: fatal("ssh_exchange_identification: "
608: "No banner received");
1.38 markus 609: }
1.75 markus 610: buf[sizeof(buf) - 1] = 0;
1.76 markus 611: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 612: break;
1.75 markus 613: debug("ssh_exchange_identification: %s", buf);
1.38 markus 614: }
1.59 markus 615: server_version_string = xstrdup(buf);
1.238 djm 616: free(fdset);
1.38 markus 617:
1.40 markus 618: /*
619: * Check that the versions match. In future this might accept
620: * several versions and set appropriate flags to handle them.
621: */
1.59 markus 622: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
623: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 624: fatal("Bad remote protocol version identification: '%.100s'", buf);
625: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 626: remote_major, remote_minor, remote_version);
1.38 markus 627:
1.59 markus 628: compat_datafellows(remote_version);
1.64 markus 629: mismatch = 0;
1.59 markus 630:
1.116 deraadt 631: switch (remote_major) {
1.64 markus 632: case 1:
633: if (remote_minor == 99 &&
634: (options.protocol & SSH_PROTO_2) &&
635: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
636: enable_compat20();
637: break;
638: }
639: if (!(options.protocol & SSH_PROTO_1)) {
640: mismatch = 1;
641: break;
642: }
643: if (remote_minor < 3) {
644: fatal("Remote machine has too old SSH software version.");
1.81 markus 645: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 646: /* We speak 1.3, too. */
647: enable_compat13();
1.81 markus 648: minor1 = 3;
1.64 markus 649: if (options.forward_agent) {
1.138 itojun 650: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 651: options.forward_agent = 0;
652: }
653: }
654: break;
655: case 2:
656: if (options.protocol & SSH_PROTO_2) {
657: enable_compat20();
658: break;
1.38 markus 659: }
1.64 markus 660: /* FALLTHROUGH */
1.68 markus 661: default:
1.64 markus 662: mismatch = 1;
663: break;
1.38 markus 664: }
1.64 markus 665: if (mismatch)
1.38 markus 666: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 667: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
668: remote_major);
1.235 djm 669: if (!client_banner_sent)
670: send_client_banner(connection_out, minor1);
1.59 markus 671: chop(server_version_string);
1.1 deraadt 672: }
673:
1.96 markus 674: /* defaults to 'no' */
1.109 itojun 675: static int
1.112 markus 676: confirm(const char *prompt)
1.1 deraadt 677: {
1.119 markus 678: const char *msg, *again = "Please type 'yes' or 'no': ";
679: char *p;
680: int ret = -1;
1.96 markus 681:
682: if (options.batch_mode)
683: return 0;
1.119 markus 684: for (msg = prompt;;msg = again) {
685: p = read_passphrase(msg, RP_ECHO);
686: if (p == NULL ||
687: (p[0] == '\0') || (p[0] == '\n') ||
688: strncasecmp(p, "no", 2) == 0)
689: ret = 0;
1.127 markus 690: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 691: ret = 1;
1.238 djm 692: free(p);
1.119 markus 693: if (ret != -1)
694: return ret;
1.1 deraadt 695: }
696: }
697:
1.219 djm 698: static int
699: check_host_cert(const char *host, const Key *host_key)
700: {
701: const char *reason;
702:
703: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
704: error("%s", reason);
705: return 0;
706: }
1.223 djm 707: if (buffer_len(&host_key->cert->critical) != 0) {
708: error("Certificate for %s contains unsupported "
709: "critical options(s)", host);
1.219 djm 710: return 0;
711: }
712: return 1;
713: }
714:
1.229 djm 715: static int
716: sockaddr_is_local(struct sockaddr *hostaddr)
717: {
718: switch (hostaddr->sa_family) {
719: case AF_INET:
720: return (ntohl(((struct sockaddr_in *)hostaddr)->
721: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
722: case AF_INET6:
723: return IN6_IS_ADDR_LOOPBACK(
724: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
725: default:
726: return 0;
727: }
728: }
729:
730: /*
731: * Prepare the hostname and ip address strings that are used to lookup
732: * host keys in known_hosts files. These may have a port number appended.
733: */
734: void
735: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
736: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
737: {
738: char ntop[NI_MAXHOST];
739:
740: /*
741: * We don't have the remote ip-address for connections
742: * using a proxy command
743: */
744: if (hostfile_ipaddr != NULL) {
745: if (options.proxy_command == NULL) {
746: if (getnameinfo(hostaddr, hostaddr->sa_len,
747: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
748: fatal("check_host_key: getnameinfo failed");
749: *hostfile_ipaddr = put_host_port(ntop, port);
750: } else {
751: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
752: "command>");
753: }
754: }
755:
756: /*
757: * Allow the user to record the key under a different name or
758: * differentiate a non-standard port. This is useful for ssh
759: * tunneling over forwarded connections or if you run multiple
760: * sshd's on different ports on the same machine.
761: */
762: if (hostfile_hostname != NULL) {
763: if (options.host_key_alias != NULL) {
764: *hostfile_hostname = xstrdup(options.host_key_alias);
765: debug("using hostkeyalias: %s", *hostfile_hostname);
766: } else {
767: *hostfile_hostname = put_host_port(hostname, port);
768: }
769: }
770: }
771:
1.39 deraadt 772: /*
1.108 markus 773: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 774: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 775: */
1.197 dtucker 776: #define RDRW 0
777: #define RDONLY 1
778: #define ROQUIET 2
1.109 itojun 779: static int
1.197 dtucker 780: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.234 djm 781: Key *host_key, int readonly,
782: char **user_hostfiles, u_int num_user_hostfiles,
783: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 784: {
1.234 djm 785: HostStatus host_status;
786: HostStatus ip_status;
1.229 djm 787: Key *raw_key = NULL;
1.189 dtucker 788: char *ip = NULL, *host = NULL;
1.204 grunk 789: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 790: char msg[1024];
1.234 djm 791: const char *type;
792: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 793: int len, cancelled_forwarding = 0;
1.234 djm 794: int local = sockaddr_is_local(hostaddr);
795: int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
1.229 djm 796: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 797: u_int i;
1.49 markus 798:
799: /*
800: * Force accepting of the host key for loopback/localhost. The
801: * problem is that if the home directory is NFS-mounted to multiple
802: * machines, localhost will refer to a different machine in each of
803: * them, and the user will get bogus HOST_CHANGED warnings. This
804: * essentially disables host authentication for localhost; however,
805: * this is probably not a real problem.
806: */
1.111 markus 807: if (options.no_host_authentication_for_localhost == 1 && local &&
808: options.host_key_alias == NULL) {
1.88 markus 809: debug("Forcing accepting of host key for "
810: "loopback/localhost.");
1.108 markus 811: return 0;
1.49 markus 812: }
1.42 markus 813:
814: /*
1.229 djm 815: * Prepare the hostname and address strings used for hostkey lookup.
816: * In some cases, these will have a port number appended.
1.42 markus 817: */
1.229 djm 818: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 819:
820: /*
1.88 markus 821: * Turn off check_host_ip if the connection is to localhost, via proxy
822: * command or if we don't have a hostname to compare with
823: */
1.189 dtucker 824: if (options.check_host_ip && (local ||
825: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 826: options.check_host_ip = 0;
1.86 markus 827:
1.229 djm 828: host_hostkeys = init_hostkeys();
1.234 djm 829: for (i = 0; i < num_user_hostfiles; i++)
830: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
831: for (i = 0; i < num_system_hostfiles; i++)
832: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 833:
834: ip_hostkeys = NULL;
835: if (!want_cert && options.check_host_ip) {
836: ip_hostkeys = init_hostkeys();
1.234 djm 837: for (i = 0; i < num_user_hostfiles; i++)
838: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
839: for (i = 0; i < num_system_hostfiles; i++)
840: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 841: }
1.38 markus 842:
1.219 djm 843: retry:
1.229 djm 844: /* Reload these as they may have changed on cert->key downgrade */
1.219 djm 845: want_cert = key_is_cert(host_key);
846: type = key_type(host_key);
847:
1.46 markus 848: /*
1.170 djm 849: * Check if the host key is present in the user's list of known
1.40 markus 850: * hosts or in the systemwide list.
851: */
1.229 djm 852: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
853: &host_found);
854:
1.40 markus 855: /*
856: * Also perform check for the ip address, skip the check if we are
1.219 djm 857: * localhost, looking for a certificate, or the hostname was an ip
858: * address to begin with.
1.40 markus 859: */
1.229 djm 860: if (!want_cert && ip_hostkeys != NULL) {
861: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
862: &ip_found);
1.38 markus 863: if (host_status == HOST_CHANGED &&
1.229 djm 864: (ip_status != HOST_CHANGED ||
865: (ip_found != NULL &&
866: !key_equal(ip_found->key, host_found->key))))
1.38 markus 867: host_ip_differ = 1;
868: } else
869: ip_status = host_status;
870:
871: switch (host_status) {
872: case HOST_OK:
873: /* The host is known and the key matches. */
1.219 djm 874: debug("Host '%.200s' is known and matches the %s host %s.",
875: host, type, want_cert ? "certificate" : "key");
1.229 djm 876: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
877: host_found->file, host_found->line);
1.219 djm 878: if (want_cert && !check_host_cert(hostname, host_key))
879: goto fail;
1.88 markus 880: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 881: if (readonly || want_cert)
1.138 itojun 882: logit("%s host key for IP address "
1.108 markus 883: "'%.128s' not in list of known hosts.",
884: type, ip);
1.234 djm 885: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 886: host_key, options.hash_known_hosts))
1.138 itojun 887: logit("Failed to add the %s host key for IP "
1.108 markus 888: "address '%.128s' to the list of known "
1.234 djm 889: "hosts (%.30s).", type, ip,
890: user_hostfiles[0]);
1.88 markus 891: else
1.138 itojun 892: logit("Warning: Permanently added the %s host "
1.108 markus 893: "key for IP address '%.128s' to the list "
894: "of known hosts.", type, ip);
1.209 grunk 895: } else if (options.visual_host_key) {
1.204 grunk 896: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
897: ra = key_fingerprint(host_key, SSH_FP_MD5,
898: SSH_FP_RANDOMART);
899: logit("Host key fingerprint is %s\n%s\n", fp, ra);
1.238 djm 900: free(ra);
901: free(fp);
1.38 markus 902: }
903: break;
904: case HOST_NEW:
1.197 dtucker 905: if (options.host_key_alias == NULL && port != 0 &&
906: port != SSH_DEFAULT_PORT) {
907: debug("checking without port identifier");
1.212 stevesk 908: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 909: ROQUIET, user_hostfiles, num_user_hostfiles,
910: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 911: debug("found matching key w/out port");
912: break;
913: }
914: }
1.219 djm 915: if (readonly || want_cert)
1.108 markus 916: goto fail;
1.38 markus 917: /* The host is new. */
918: if (options.strict_host_key_checking == 1) {
1.108 markus 919: /*
920: * User has requested strict host key checking. We
921: * will not add the host key automatically. The only
922: * alternative left is to abort.
923: */
924: error("No %s host key is known for %.200s and you "
925: "have requested strict checking.", type, host);
926: goto fail;
1.38 markus 927: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 928: char msg1[1024], msg2[1024];
929:
1.229 djm 930: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 931: snprintf(msg1, sizeof(msg1),
1.168 djm 932: "\nbut keys of different type are already"
933: " known for this host.");
1.145 jakob 934: else
935: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 936: /* The default */
1.100 markus 937: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.204 grunk 938: ra = key_fingerprint(host_key, SSH_FP_MD5,
939: SSH_FP_RANDOMART);
1.145 jakob 940: msg2[0] = '\0';
941: if (options.verify_host_key_dns) {
1.153 jakob 942: if (matching_host_key_dns)
1.145 jakob 943: snprintf(msg2, sizeof(msg2),
944: "Matching host key fingerprint"
945: " found in DNS.\n");
946: else
947: snprintf(msg2, sizeof(msg2),
948: "No matching host key fingerprint"
949: " found in DNS.\n");
950: }
1.119 markus 951: snprintf(msg, sizeof(msg),
1.108 markus 952: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 953: "established%s\n"
1.209 grunk 954: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 955: "Are you sure you want to continue connecting "
1.132 markus 956: "(yes/no)? ",
1.209 grunk 957: host, ip, msg1, type, fp,
958: options.visual_host_key ? "\n" : "",
959: options.visual_host_key ? ra : "",
960: msg2);
1.238 djm 961: free(ra);
962: free(fp);
1.119 markus 963: if (!confirm(msg))
1.108 markus 964: goto fail;
1.38 markus 965: }
1.161 djm 966: /*
967: * If not in strict mode, add the key automatically to the
968: * local known_hosts file.
969: */
1.88 markus 970: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 971: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 972: hostp = hostline;
1.161 djm 973: if (options.hash_known_hosts) {
974: /* Add hash of host and IP separately */
1.234 djm 975: r = add_host_to_hostfile(user_hostfiles[0],
976: host, host_key, options.hash_known_hosts) &&
977: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 978: host_key, options.hash_known_hosts);
979: } else {
980: /* Add unhashed "host,ip" */
1.234 djm 981: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 982: hostline, host_key,
983: options.hash_known_hosts);
984: }
985: } else {
1.234 djm 986: r = add_host_to_hostfile(user_hostfiles[0], host,
987: host_key, options.hash_known_hosts);
1.38 markus 988: hostp = host;
1.161 djm 989: }
1.38 markus 990:
1.161 djm 991: if (!r)
1.138 itojun 992: logit("Failed to add the host to the list of known "
1.234 djm 993: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 994: else
1.138 itojun 995: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 996: "list of known hosts.", hostp, type);
1.38 markus 997: break;
1.220 djm 998: case HOST_REVOKED:
999: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1000: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1001: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1002: error("The %s host key for %s is marked as revoked.", type, host);
1003: error("This could mean that a stolen key is being used to");
1004: error("impersonate this host.");
1005:
1006: /*
1007: * If strict host key checking is in use, the user will have
1008: * to edit the key manually and we can only abort.
1009: */
1010: if (options.strict_host_key_checking) {
1011: error("%s host key for %.200s was revoked and you have "
1012: "requested strict checking.", type, host);
1013: goto fail;
1014: }
1015: goto continue_unsafe;
1016:
1.38 markus 1017: case HOST_CHANGED:
1.219 djm 1018: if (want_cert) {
1019: /*
1020: * This is only a debug() since it is valid to have
1021: * CAs with wildcard DNS matches that don't match
1022: * all hosts that one might visit.
1023: */
1024: debug("Host certificate authority does not "
1.229 djm 1025: "match %s in %s:%lu", CA_MARKER,
1026: host_found->file, host_found->line);
1.219 djm 1027: goto fail;
1028: }
1.197 dtucker 1029: if (readonly == ROQUIET)
1030: goto fail;
1.38 markus 1031: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1032: char *key_msg;
1.38 markus 1033: if (ip_status == HOST_NEW)
1.158 avsm 1034: key_msg = "is unknown";
1.38 markus 1035: else if (ip_status == HOST_OK)
1.158 avsm 1036: key_msg = "is unchanged";
1.38 markus 1037: else
1.158 avsm 1038: key_msg = "has a different value";
1.38 markus 1039: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1040: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1041: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1042: error("The %s host key for %s has changed,", type, host);
1.208 ian 1043: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1044: error("%s. This could either mean that", key_msg);
1.38 markus 1045: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1046: error("and its host key have changed at the same time.");
1.88 markus 1047: if (ip_status != HOST_NEW)
1.229 djm 1048: error("Offending key for IP in %s:%lu",
1049: ip_found->file, ip_found->line);
1.38 markus 1050: }
1051: /* The host key has changed. */
1.150 jakob 1052: warn_changed_key(host_key);
1.38 markus 1053: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1054: user_hostfiles[0]);
1.229 djm 1055: error("Offending %s key in %s:%lu", key_type(host_found->key),
1056: host_found->file, host_found->line);
1.38 markus 1057:
1.40 markus 1058: /*
1059: * If strict host key checking is in use, the user will have
1060: * to edit the key manually and we can only abort.
1061: */
1.108 markus 1062: if (options.strict_host_key_checking) {
1063: error("%s host key for %.200s has changed and you have "
1064: "requested strict checking.", type, host);
1065: goto fail;
1066: }
1.38 markus 1067:
1.220 djm 1068: continue_unsafe:
1.40 markus 1069: /*
1070: * If strict host key checking has not been requested, allow
1.144 djm 1071: * the connection but without MITM-able authentication or
1.194 stevesk 1072: * forwarding.
1.40 markus 1073: */
1.38 markus 1074: if (options.password_authentication) {
1.108 markus 1075: error("Password authentication is disabled to avoid "
1076: "man-in-the-middle attacks.");
1.38 markus 1077: options.password_authentication = 0;
1.210 dtucker 1078: cancelled_forwarding = 1;
1.144 djm 1079: }
1080: if (options.kbd_interactive_authentication) {
1081: error("Keyboard-interactive authentication is disabled"
1082: " to avoid man-in-the-middle attacks.");
1083: options.kbd_interactive_authentication = 0;
1084: options.challenge_response_authentication = 0;
1.210 dtucker 1085: cancelled_forwarding = 1;
1.144 djm 1086: }
1087: if (options.challenge_response_authentication) {
1088: error("Challenge/response authentication is disabled"
1089: " to avoid man-in-the-middle attacks.");
1090: options.challenge_response_authentication = 0;
1.210 dtucker 1091: cancelled_forwarding = 1;
1.38 markus 1092: }
1093: if (options.forward_agent) {
1.108 markus 1094: error("Agent forwarding is disabled to avoid "
1095: "man-in-the-middle attacks.");
1.38 markus 1096: options.forward_agent = 0;
1.210 dtucker 1097: cancelled_forwarding = 1;
1.83 markus 1098: }
1099: if (options.forward_x11) {
1.108 markus 1100: error("X11 forwarding is disabled to avoid "
1101: "man-in-the-middle attacks.");
1.83 markus 1102: options.forward_x11 = 0;
1.210 dtucker 1103: cancelled_forwarding = 1;
1.83 markus 1104: }
1.108 markus 1105: if (options.num_local_forwards > 0 ||
1106: options.num_remote_forwards > 0) {
1107: error("Port forwarding is disabled to avoid "
1108: "man-in-the-middle attacks.");
1109: options.num_local_forwards =
1.118 deraadt 1110: options.num_remote_forwards = 0;
1.210 dtucker 1111: cancelled_forwarding = 1;
1.194 stevesk 1112: }
1113: if (options.tun_open != SSH_TUNMODE_NO) {
1114: error("Tunnel forwarding is disabled to avoid "
1115: "man-in-the-middle attacks.");
1116: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1117: cancelled_forwarding = 1;
1.38 markus 1118: }
1.210 dtucker 1119: if (options.exit_on_forward_failure && cancelled_forwarding)
1120: fatal("Error: forwarding disabled due to host key "
1121: "check failure");
1122:
1.40 markus 1123: /*
1124: * XXX Should permit the user to change to use the new id.
1125: * This could be done by converting the host key to an
1126: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1127: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1128: * accept the authentication.
1129: */
1.38 markus 1130: break;
1.132 markus 1131: case HOST_FOUND:
1132: fatal("internal error");
1133: break;
1.88 markus 1134: }
1135:
1136: if (options.check_host_ip && host_status != HOST_CHANGED &&
1137: ip_status == HOST_CHANGED) {
1.119 markus 1138: snprintf(msg, sizeof(msg),
1139: "Warning: the %s host key for '%.200s' "
1140: "differs from the key for the IP address '%.128s'"
1.229 djm 1141: "\nOffending key for IP in %s:%lu",
1142: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1143: if (host_status == HOST_OK) {
1144: len = strlen(msg);
1145: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1146: "\nMatching host key in %s:%lu",
1147: host_found->file, host_found->line);
1.119 markus 1148: }
1.88 markus 1149: if (options.strict_host_key_checking == 1) {
1.143 djm 1150: logit("%s", msg);
1.108 markus 1151: error("Exiting, you have requested strict checking.");
1152: goto fail;
1.88 markus 1153: } else if (options.strict_host_key_checking == 2) {
1.119 markus 1154: strlcat(msg, "\nAre you sure you want "
1155: "to continue connecting (yes/no)? ", sizeof(msg));
1156: if (!confirm(msg))
1.108 markus 1157: goto fail;
1.119 markus 1158: } else {
1.143 djm 1159: logit("%s", msg);
1.88 markus 1160: }
1.38 markus 1161: }
1.82 provos 1162:
1.238 djm 1163: free(ip);
1164: free(host);
1.229 djm 1165: if (host_hostkeys != NULL)
1166: free_hostkeys(host_hostkeys);
1167: if (ip_hostkeys != NULL)
1168: free_hostkeys(ip_hostkeys);
1.108 markus 1169: return 0;
1170:
1171: fail:
1.220 djm 1172: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1173: /*
1174: * No matching certificate. Downgrade cert to raw key and
1175: * search normally.
1176: */
1177: debug("No matching CA found. Retry with plain key");
1178: raw_key = key_from_private(host_key);
1179: if (key_drop_cert(raw_key) != 0)
1180: fatal("Couldn't drop certificate");
1181: host_key = raw_key;
1182: goto retry;
1183: }
1184: if (raw_key != NULL)
1185: key_free(raw_key);
1.238 djm 1186: free(ip);
1187: free(host);
1.229 djm 1188: if (host_hostkeys != NULL)
1189: free_hostkeys(host_hostkeys);
1190: if (ip_hostkeys != NULL)
1191: free_hostkeys(ip_hostkeys);
1.108 markus 1192: return -1;
1193: }
1194:
1.140 jakob 1195: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1196: int
1197: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1198: {
1.153 jakob 1199: int flags = 0;
1.229 djm 1200: char *fp;
1201:
1202: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1203: debug("Server host key: %s %s", key_type(host_key), fp);
1.238 djm 1204: free(fp);
1.140 jakob 1205:
1.219 djm 1206: /* XXX certs are not yet supported for DNS */
1207: if (!key_is_cert(host_key) && options.verify_host_key_dns &&
1.153 jakob 1208: verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
1209: if (flags & DNS_VERIFY_FOUND) {
1210:
1211: if (options.verify_host_key_dns == 1 &&
1212: flags & DNS_VERIFY_MATCH &&
1213: flags & DNS_VERIFY_SECURE)
1214: return 0;
1215:
1216: if (flags & DNS_VERIFY_MATCH) {
1217: matching_host_key_dns = 1;
1218: } else {
1219: warn_changed_key(host_key);
1220: error("Update the SSHFP RR in DNS with the new "
1221: "host key to get rid of this message.");
1222: }
1.140 jakob 1223: }
1224: }
1.108 markus 1225:
1.234 djm 1226: return check_host_key(host, hostaddr, options.port, host_key, RDRW,
1227: options.user_hostfiles, options.num_user_hostfiles,
1228: options.system_hostfiles, options.num_system_hostfiles);
1.51 markus 1229: }
1.70 markus 1230:
1.51 markus 1231: /*
1232: * Starts a dialog with the server, and authenticates the current user on the
1233: * server. This does not need any extra privileges. The basic connection
1234: * to the server must already have been established before this is called.
1235: * If login fails, this function prints an error and never returns.
1236: * This function does not require super-user privileges.
1237: */
1238: void
1.120 markus 1239: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1240: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1241: {
1242: char *host, *cp;
1.70 markus 1243: char *server_user, *local_user;
1244:
1245: local_user = xstrdup(pw->pw_name);
1246: server_user = options.user ? options.user : local_user;
1.51 markus 1247:
1248: /* Convert the user-supplied hostname into all lowercase. */
1249: host = xstrdup(orighost);
1250: for (cp = host; *cp; cp++)
1251: if (isupper(*cp))
1.178 deraadt 1252: *cp = (char)tolower(*cp);
1.51 markus 1253:
1254: /* Exchange protocol version identification strings with the server. */
1.202 djm 1255: ssh_exchange_identification(timeout_ms);
1.51 markus 1256:
1257: /* Put the connection into non-blocking mode. */
1258: packet_set_nonblocking();
1259:
1260: /* key exchange */
1261: /* authenticate user */
1.59 markus 1262: if (compat20) {
1.229 djm 1263: ssh_kex2(host, hostaddr, port);
1.120 markus 1264: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 1265: } else {
1266: ssh_kex(host, hostaddr);
1.120 markus 1267: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 1268: }
1.238 djm 1269: free(local_user);
1.97 markus 1270: }
1271:
1272: void
1273: ssh_put_password(char *password)
1274: {
1275: int size;
1276: char *padded;
1277:
1.99 deraadt 1278: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1279: packet_put_cstring(password);
1.99 deraadt 1280: return;
1281: }
1.97 markus 1282: size = roundup(strlen(password) + 1, 32);
1.179 djm 1283: padded = xcalloc(1, size);
1.97 markus 1284: strlcpy(padded, password, size);
1285: packet_put_string(padded, size);
1286: memset(padded, 0, size);
1.238 djm 1287: free(padded);
1.132 markus 1288: }
1289:
1290: /* print all known host keys for a given host, but skip keys of given type */
1291: static int
1.229 djm 1292: show_other_keys(struct hostkeys *hostkeys, Key *key)
1.132 markus 1293: {
1.225 djm 1294: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, KEY_ECDSA, -1};
1.229 djm 1295: int i, ret = 0;
1296: char *fp, *ra;
1297: const struct hostkey_entry *found;
1.132 markus 1298:
1299: for (i = 0; type[i] != -1; i++) {
1300: if (type[i] == key->type)
1301: continue;
1.229 djm 1302: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1303: continue;
1.229 djm 1304: fp = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_HEX);
1305: ra = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_RANDOMART);
1306: logit("WARNING: %s key found for host %s\n"
1307: "in %s:%lu\n"
1308: "%s key fingerprint %s.",
1309: key_type(found->key),
1310: found->host, found->file, found->line,
1311: key_type(found->key), fp);
1312: if (options.visual_host_key)
1313: logit("%s", ra);
1.238 djm 1314: free(ra);
1315: free(fp);
1.229 djm 1316: ret = 1;
1.132 markus 1317: }
1.229 djm 1318: return ret;
1.150 jakob 1319: }
1320:
1321: static void
1322: warn_changed_key(Key *host_key)
1323: {
1324: char *fp;
1325:
1326: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1327:
1328: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1329: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1330: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1331: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1332: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1333: error("It is also possible that a host key has just been changed.");
1.150 jakob 1334: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.230 markus 1335: key_type(host_key), fp);
1.150 jakob 1336: error("Please contact your system administrator.");
1337:
1.238 djm 1338: free(fp);
1.171 reyk 1339: }
1340:
1341: /*
1342: * Execute a local command
1343: */
1344: int
1345: ssh_local_cmd(const char *args)
1346: {
1347: char *shell;
1348: pid_t pid;
1349: int status;
1.231 djm 1350: void (*osighand)(int);
1.171 reyk 1351:
1352: if (!options.permit_local_command ||
1353: args == NULL || !*args)
1354: return (1);
1355:
1.226 djm 1356: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1357: shell = _PATH_BSHELL;
1358:
1.231 djm 1359: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1360: pid = fork();
1361: if (pid == 0) {
1.232 djm 1362: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1363: debug3("Executing %s -c \"%s\"", shell, args);
1364: execl(shell, shell, "-c", args, (char *)NULL);
1365: error("Couldn't execute %s -c \"%s\": %s",
1366: shell, args, strerror(errno));
1367: _exit(1);
1368: } else if (pid == -1)
1369: fatal("fork failed: %.100s", strerror(errno));
1370: while (waitpid(pid, &status, 0) == -1)
1371: if (errno != EINTR)
1372: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1373: signal(SIGCHLD, osighand);
1.171 reyk 1374:
1375: if (!WIFEXITED(status))
1376: return (1);
1377:
1378: return (WEXITSTATUS(status));
1.1 deraadt 1379: }
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