Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.249
1.249 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.248 2014/04/29 18:01:49 markus 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:
1.241 djm 79: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 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:
164: return 0;
165: }
166:
1.39 deraadt 167: /*
168: * Connect to the given ssh server using a proxy command.
169: */
1.109 itojun 170: static int
1.124 markus 171: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 172: {
1.239 djm 173: char *command_string;
1.38 markus 174: int pin[2], pout[2];
1.69 deraadt 175: pid_t pid;
1.239 djm 176: char *shell;
1.237 markus 177:
1.226 djm 178: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 179: shell = _PATH_BSHELL;
1.38 markus 180:
181: /* Create pipes for communicating with the proxy. */
182: if (pipe(pin) < 0 || pipe(pout) < 0)
183: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 184: strerror(errno));
1.38 markus 185:
1.239 djm 186: command_string = expand_proxy_command(proxy_command, options.user,
187: host, port);
1.38 markus 188: debug("Executing proxy command: %.500s", command_string);
189:
190: /* Fork and execute the proxy command. */
191: if ((pid = fork()) == 0) {
192: char *argv[10];
193:
194: /* Child. Permanently give up superuser privileges. */
1.184 markus 195: permanently_drop_suid(original_real_uid);
1.38 markus 196:
197: /* Redirect stdin and stdout. */
198: close(pin[1]);
199: if (pin[0] != 0) {
200: if (dup2(pin[0], 0) < 0)
201: perror("dup2 stdin");
202: close(pin[0]);
203: }
204: close(pout[0]);
205: if (dup2(pout[1], 1) < 0)
206: perror("dup2 stdout");
207: /* Cannot be 1 because pin allocated two descriptors. */
208: close(pout[1]);
209:
210: /* Stderr is left as it is so that error messages get
211: printed on the user's terminal. */
1.201 djm 212: argv[0] = shell;
1.38 markus 213: argv[1] = "-c";
214: argv[2] = command_string;
215: argv[3] = NULL;
216:
217: /* Execute the proxy command. Note that we gave up any
218: extra privileges above. */
1.232 djm 219: signal(SIGPIPE, SIG_DFL);
1.89 markus 220: execv(argv[0], argv);
221: perror(argv[0]);
1.38 markus 222: exit(1);
223: }
224: /* Parent. */
225: if (pid < 0)
226: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 227: else
228: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 229:
230: /* Close child side of the descriptors. */
231: close(pin[0]);
232: close(pout[1]);
233:
234: /* Free the command name. */
1.238 djm 235: free(command_string);
1.38 markus 236:
237: /* Set the connection file descriptors. */
238: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 239:
1.110 markus 240: /* Indicate OK return */
241: return 0;
1.227 djm 242: }
243:
244: void
245: ssh_kill_proxy_command(void)
246: {
247: /*
248: * Send SIGHUP to proxy command if used. We don't wait() in
249: * case it hangs and instead rely on init to reap the child
250: */
251: if (proxy_command_pid > 1)
1.228 djm 252: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 253: }
254:
1.39 deraadt 255: /*
256: * Creates a (possibly privileged) socket for use as the ssh connection.
257: */
1.109 itojun 258: static int
1.139 markus 259: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 260: {
1.240 djm 261: int sock, r, gaierr;
1.246 djm 262: struct addrinfo hints, *res = NULL;
1.1 deraadt 263:
1.217 dtucker 264: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 265: if (sock < 0) {
1.240 djm 266: error("socket: %s", strerror(errno));
1.216 dtucker 267: return -1;
268: }
269: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 270:
271: /* Bind the socket to an alternative local IP address */
1.240 djm 272: if (options.bind_address == NULL && !privileged)
1.105 markus 273: return sock;
274:
1.246 djm 275: if (options.bind_address) {
276: memset(&hints, 0, sizeof(hints));
277: hints.ai_family = ai->ai_family;
278: hints.ai_socktype = ai->ai_socktype;
279: hints.ai_protocol = ai->ai_protocol;
280: hints.ai_flags = AI_PASSIVE;
281: gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
282: if (gaierr) {
283: error("getaddrinfo: %s: %s", options.bind_address,
284: ssh_gai_strerror(gaierr));
285: close(sock);
286: return -1;
287: }
1.105 markus 288: }
1.240 djm 289: /*
290: * If we are running as root and want to connect to a privileged
291: * port, bind our own socket to a privileged port.
292: */
293: if (privileged) {
294: PRIV_START;
1.246 djm 295: r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
1.240 djm 296: PRIV_END;
297: if (r < 0) {
298: error("bindresvport_sa: af=%d %s", ai->ai_family,
299: strerror(errno));
300: goto fail;
301: }
302: } else {
303: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
304: error("bind: %s: %s", options.bind_address,
305: strerror(errno));
306: fail:
307: close(sock);
308: freeaddrinfo(res);
309: return -1;
310: }
1.38 markus 311: }
1.246 djm 312: if (res != NULL)
313: freeaddrinfo(res);
1.38 markus 314: return sock;
1.1 deraadt 315: }
316:
1.141 djm 317: static int
318: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 319: socklen_t addrlen, int *timeoutp)
1.141 djm 320: {
321: fd_set *fdset;
1.202 djm 322: struct timeval tv, t_start;
1.141 djm 323: socklen_t optlen;
1.179 djm 324: int optval, rc, result = -1;
1.141 djm 325:
1.202 djm 326: gettimeofday(&t_start, NULL);
327:
328: if (*timeoutp <= 0) {
329: result = connect(sockfd, serv_addr, addrlen);
330: goto done;
331: }
1.141 djm 332:
1.156 djm 333: set_nonblock(sockfd);
1.141 djm 334: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 335: if (rc == 0) {
336: unset_nonblock(sockfd);
1.202 djm 337: result = 0;
338: goto done;
339: }
340: if (errno != EINPROGRESS) {
341: result = -1;
342: goto done;
1.156 djm 343: }
1.141 djm 344:
1.179 djm 345: fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
346: sizeof(fd_mask));
1.141 djm 347: FD_SET(sockfd, fdset);
1.202 djm 348: ms_to_timeval(&tv, *timeoutp);
1.141 djm 349:
1.162 deraadt 350: for (;;) {
1.141 djm 351: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
352: if (rc != -1 || errno != EINTR)
353: break;
354: }
355:
1.162 deraadt 356: switch (rc) {
1.141 djm 357: case 0:
358: /* Timed out */
359: errno = ETIMEDOUT;
1.142 djm 360: break;
1.141 djm 361: case -1:
362: /* Select error */
1.154 djm 363: debug("select: %s", strerror(errno));
1.142 djm 364: break;
1.141 djm 365: case 1:
366: /* Completed or failed */
367: optval = 0;
368: optlen = sizeof(optval);
1.154 djm 369: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 370: &optlen) == -1) {
1.154 djm 371: debug("getsockopt: %s", strerror(errno));
1.142 djm 372: break;
1.148 markus 373: }
1.141 djm 374: if (optval != 0) {
375: errno = optval;
1.142 djm 376: break;
1.141 djm 377: }
1.142 djm 378: result = 0;
1.156 djm 379: unset_nonblock(sockfd);
1.141 djm 380: break;
381: default:
382: /* Should not occur */
383: fatal("Bogus return (%d) from select()", rc);
384: }
385:
1.238 djm 386: free(fdset);
1.202 djm 387:
388: done:
389: if (result == 0 && *timeoutp > 0) {
390: ms_subtract_diff(&t_start, timeoutp);
391: if (*timeoutp <= 0) {
392: errno = ETIMEDOUT;
393: result = -1;
394: }
395: }
396:
1.142 djm 397: return (result);
1.141 djm 398: }
399:
1.39 deraadt 400: /*
1.49 markus 401: * Opens a TCP/IP connection to the remote server on the given host.
402: * The address of the remote host will be returned in hostaddr.
1.124 markus 403: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 404: * a privileged port will be allocated to make the connection.
1.124 markus 405: * This requires super-user privileges if needpriv is true.
1.39 deraadt 406: * Connection_attempts specifies the maximum number of tries (one per
407: * second). If proxy_command is non-NULL, it specifies the command (with %h
408: * and %p substituted for host and port, respectively) to use to contact
409: * the daemon.
410: */
1.241 djm 411: static int
412: ssh_connect_direct(const char *host, struct addrinfo *aitop,
413: struct sockaddr_storage *hostaddr, u_short port, int family,
414: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
1.1 deraadt 415: {
1.90 markus 416: int on = 1;
1.49 markus 417: int sock = -1, attempt;
1.90 markus 418: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 419: struct addrinfo *ai;
1.38 markus 420:
1.136 markus 421: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 422:
1.181 markus 423: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 424: if (attempt > 0) {
425: /* Sleep a moment before retrying. */
426: sleep(1);
1.38 markus 427: debug("Trying again...");
1.200 markus 428: }
1.181 markus 429: /*
430: * Loop through addresses for this host, and try each one in
431: * sequence until the connection succeeds.
432: */
1.49 markus 433: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 434: if (ai->ai_family != AF_INET &&
435: ai->ai_family != AF_INET6)
1.49 markus 436: continue;
437: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
438: ntop, sizeof(ntop), strport, sizeof(strport),
439: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
440: error("ssh_connect: getnameinfo failed");
441: continue;
442: }
443: debug("Connecting to %.200s [%.100s] port %s.",
444: host, ntop, strport);
445:
446: /* Create a socket for connecting. */
1.139 markus 447: sock = ssh_create_socket(needpriv, ai);
1.49 markus 448: if (sock < 0)
1.110 markus 449: /* Any error is already output */
1.49 markus 450: continue;
451:
1.141 djm 452: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 453: timeout_ms) >= 0) {
1.49 markus 454: /* Successful connection. */
1.102 markus 455: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 456: break;
1.49 markus 457: } else {
1.131 itojun 458: debug("connect to address %s port %s: %s",
459: ntop, strport, strerror(errno));
1.38 markus 460: close(sock);
1.181 markus 461: sock = -1;
1.38 markus 462: }
463: }
1.181 markus 464: if (sock != -1)
1.49 markus 465: break; /* Successful connection. */
1.38 markus 466: }
1.49 markus 467:
1.38 markus 468: /* Return failure if we didn't get a successful connection. */
1.181 markus 469: if (sock == -1) {
1.159 markus 470: error("ssh: connect to host %s port %s: %s",
1.130 itojun 471: host, strport, strerror(errno));
1.159 markus 472: return (-1);
1.130 itojun 473: }
1.38 markus 474:
475: debug("Connection established.");
1.90 markus 476:
1.155 markus 477: /* Set SO_KEEPALIVE if requested. */
1.202 djm 478: if (want_keepalive &&
1.90 markus 479: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
480: sizeof(on)) < 0)
481: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 482:
483: /* Set the connection. */
484: packet_set_connection(sock, sock);
1.1 deraadt 485:
1.110 markus 486: return 0;
1.59 markus 487: }
488:
1.241 djm 489: int
490: ssh_connect(const char *host, struct addrinfo *addrs,
491: struct sockaddr_storage *hostaddr, u_short port, int family,
492: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
493: {
494: if (options.proxy_command == NULL) {
495: return ssh_connect_direct(host, addrs, hostaddr, port, family,
496: connection_attempts, timeout_ms, want_keepalive, needpriv);
497: } else if (strcmp(options.proxy_command, "-") == 0) {
498: packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
499: return 0; /* Always succeeds */
500: } else if (options.proxy_use_fdpass) {
501: return ssh_proxy_fdpass_connect(host, port,
502: options.proxy_command);
503: }
504: return ssh_proxy_connect(host, port, options.proxy_command);
505: }
506:
1.235 djm 507: static void
508: send_client_banner(int connection_out, int minor1)
509: {
510: /* Send our own protocol version identification. */
511: if (compat20) {
512: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
513: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
514: } else {
515: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n",
516: PROTOCOL_MAJOR_1, minor1, SSH_VERSION);
517: }
518: if (roaming_atomicio(vwrite, connection_out, client_version_string,
519: strlen(client_version_string)) != strlen(client_version_string))
520: fatal("write: %.100s", strerror(errno));
521: chop(client_version_string);
522: debug("Local version string %.100s", client_version_string);
523: }
524:
1.43 markus 525: /*
1.39 deraadt 526: * Waits for the server identification string, and sends our own
527: * identification string.
528: */
1.213 andreas 529: void
1.202 djm 530: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 531: {
1.38 markus 532: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 533: int remote_major, remote_minor, mismatch;
1.38 markus 534: int connection_in = packet_get_connection_in();
535: int connection_out = packet_get_connection_out();
1.235 djm 536: int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
1.185 djm 537: u_int i, n;
1.202 djm 538: size_t len;
539: int fdsetsz, remaining, rc;
540: struct timeval t_start, t_remaining;
541: fd_set *fdset;
542:
543: fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
544: fdset = xcalloc(1, fdsetsz);
1.38 markus 545:
1.235 djm 546: /*
547: * If we are SSH2-only then we can send the banner immediately and
548: * save a round-trip.
549: */
550: if (options.protocol == SSH_PROTO_2) {
551: enable_compat20();
552: send_client_banner(connection_out, 0);
553: client_banner_sent = 1;
554: }
555:
1.163 avsm 556: /* Read other side's version identification. */
1.202 djm 557: remaining = timeout_ms;
1.185 djm 558: for (n = 0;;) {
1.75 markus 559: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 560: if (timeout_ms > 0) {
561: gettimeofday(&t_start, NULL);
562: ms_to_timeval(&t_remaining, remaining);
563: FD_SET(connection_in, fdset);
564: rc = select(connection_in + 1, fdset, NULL,
565: fdset, &t_remaining);
566: ms_subtract_diff(&t_start, &remaining);
567: if (rc == 0 || remaining <= 0)
568: fatal("Connection timed out during "
569: "banner exchange");
570: if (rc == -1) {
571: if (errno == EINTR)
572: continue;
573: fatal("ssh_exchange_identification: "
574: "select: %s", strerror(errno));
575: }
576: }
577:
1.214 andreas 578: len = roaming_atomicio(read, connection_in, &buf[i], 1);
1.163 avsm 579:
1.167 djm 580: if (len != 1 && errno == EPIPE)
1.202 djm 581: fatal("ssh_exchange_identification: "
582: "Connection closed by remote host");
1.163 avsm 583: else if (len != 1)
1.202 djm 584: fatal("ssh_exchange_identification: "
585: "read: %.100s", strerror(errno));
1.75 markus 586: if (buf[i] == '\r') {
587: buf[i] = '\n';
588: buf[i + 1] = 0;
589: continue; /**XXX wait for \n */
590: }
591: if (buf[i] == '\n') {
592: buf[i + 1] = 0;
593: break;
594: }
1.185 djm 595: if (++n > 65536)
1.202 djm 596: fatal("ssh_exchange_identification: "
597: "No banner received");
1.38 markus 598: }
1.75 markus 599: buf[sizeof(buf) - 1] = 0;
1.76 markus 600: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 601: break;
1.75 markus 602: debug("ssh_exchange_identification: %s", buf);
1.38 markus 603: }
1.59 markus 604: server_version_string = xstrdup(buf);
1.238 djm 605: free(fdset);
1.38 markus 606:
1.40 markus 607: /*
608: * Check that the versions match. In future this might accept
609: * several versions and set appropriate flags to handle them.
610: */
1.59 markus 611: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
612: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 613: fatal("Bad remote protocol version identification: '%.100s'", buf);
614: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 615: remote_major, remote_minor, remote_version);
1.38 markus 616:
1.59 markus 617: compat_datafellows(remote_version);
1.64 markus 618: mismatch = 0;
1.59 markus 619:
1.116 deraadt 620: switch (remote_major) {
1.64 markus 621: case 1:
622: if (remote_minor == 99 &&
623: (options.protocol & SSH_PROTO_2) &&
624: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
625: enable_compat20();
626: break;
627: }
628: if (!(options.protocol & SSH_PROTO_1)) {
629: mismatch = 1;
630: break;
631: }
632: if (remote_minor < 3) {
633: fatal("Remote machine has too old SSH software version.");
1.81 markus 634: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 635: /* We speak 1.3, too. */
636: enable_compat13();
1.81 markus 637: minor1 = 3;
1.64 markus 638: if (options.forward_agent) {
1.138 itojun 639: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 640: options.forward_agent = 0;
641: }
642: }
643: break;
644: case 2:
645: if (options.protocol & SSH_PROTO_2) {
646: enable_compat20();
647: break;
1.38 markus 648: }
1.64 markus 649: /* FALLTHROUGH */
1.68 markus 650: default:
1.64 markus 651: mismatch = 1;
652: break;
1.38 markus 653: }
1.64 markus 654: if (mismatch)
1.38 markus 655: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 656: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
657: remote_major);
1.244 djm 658: if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
659: fatal("Server version \"%.100s\" uses unsafe key agreement; "
660: "refusing connection", remote_version);
1.243 djm 661: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
662: logit("Server version \"%.100s\" uses unsafe RSA signature "
663: "scheme; disabling use of RSA keys", remote_version);
1.235 djm 664: if (!client_banner_sent)
665: send_client_banner(connection_out, minor1);
1.59 markus 666: chop(server_version_string);
1.1 deraadt 667: }
668:
1.96 markus 669: /* defaults to 'no' */
1.109 itojun 670: static int
1.112 markus 671: confirm(const char *prompt)
1.1 deraadt 672: {
1.119 markus 673: const char *msg, *again = "Please type 'yes' or 'no': ";
674: char *p;
675: int ret = -1;
1.96 markus 676:
677: if (options.batch_mode)
678: return 0;
1.119 markus 679: for (msg = prompt;;msg = again) {
680: p = read_passphrase(msg, RP_ECHO);
681: if (p == NULL ||
682: (p[0] == '\0') || (p[0] == '\n') ||
683: strncasecmp(p, "no", 2) == 0)
684: ret = 0;
1.127 markus 685: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 686: ret = 1;
1.238 djm 687: free(p);
1.119 markus 688: if (ret != -1)
689: return ret;
1.1 deraadt 690: }
691: }
692:
1.219 djm 693: static int
694: check_host_cert(const char *host, const Key *host_key)
695: {
696: const char *reason;
697:
698: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
699: error("%s", reason);
700: return 0;
701: }
1.249 ! djm 702: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 703: error("Certificate for %s contains unsupported "
704: "critical options(s)", host);
1.219 djm 705: return 0;
706: }
707: return 1;
708: }
709:
1.229 djm 710: static int
711: sockaddr_is_local(struct sockaddr *hostaddr)
712: {
713: switch (hostaddr->sa_family) {
714: case AF_INET:
715: return (ntohl(((struct sockaddr_in *)hostaddr)->
716: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
717: case AF_INET6:
718: return IN6_IS_ADDR_LOOPBACK(
719: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
720: default:
721: return 0;
722: }
723: }
724:
725: /*
726: * Prepare the hostname and ip address strings that are used to lookup
727: * host keys in known_hosts files. These may have a port number appended.
728: */
729: void
730: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
731: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
732: {
733: char ntop[NI_MAXHOST];
734:
735: /*
736: * We don't have the remote ip-address for connections
737: * using a proxy command
738: */
739: if (hostfile_ipaddr != NULL) {
740: if (options.proxy_command == NULL) {
741: if (getnameinfo(hostaddr, hostaddr->sa_len,
742: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
743: fatal("check_host_key: getnameinfo failed");
744: *hostfile_ipaddr = put_host_port(ntop, port);
745: } else {
746: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
747: "command>");
748: }
749: }
750:
751: /*
752: * Allow the user to record the key under a different name or
753: * differentiate a non-standard port. This is useful for ssh
754: * tunneling over forwarded connections or if you run multiple
755: * sshd's on different ports on the same machine.
756: */
757: if (hostfile_hostname != NULL) {
758: if (options.host_key_alias != NULL) {
759: *hostfile_hostname = xstrdup(options.host_key_alias);
760: debug("using hostkeyalias: %s", *hostfile_hostname);
761: } else {
762: *hostfile_hostname = put_host_port(hostname, port);
763: }
764: }
765: }
766:
1.39 deraadt 767: /*
1.108 markus 768: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 769: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 770: */
1.197 dtucker 771: #define RDRW 0
772: #define RDONLY 1
773: #define ROQUIET 2
1.109 itojun 774: static int
1.197 dtucker 775: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.234 djm 776: Key *host_key, int readonly,
777: char **user_hostfiles, u_int num_user_hostfiles,
778: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 779: {
1.234 djm 780: HostStatus host_status;
781: HostStatus ip_status;
1.229 djm 782: Key *raw_key = NULL;
1.189 dtucker 783: char *ip = NULL, *host = NULL;
1.204 grunk 784: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 785: char msg[1024];
1.234 djm 786: const char *type;
787: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 788: int len, cancelled_forwarding = 0;
1.234 djm 789: int local = sockaddr_is_local(hostaddr);
790: int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
1.229 djm 791: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 792: u_int i;
1.49 markus 793:
794: /*
795: * Force accepting of the host key for loopback/localhost. The
796: * problem is that if the home directory is NFS-mounted to multiple
797: * machines, localhost will refer to a different machine in each of
798: * them, and the user will get bogus HOST_CHANGED warnings. This
799: * essentially disables host authentication for localhost; however,
800: * this is probably not a real problem.
801: */
1.111 markus 802: if (options.no_host_authentication_for_localhost == 1 && local &&
803: options.host_key_alias == NULL) {
1.88 markus 804: debug("Forcing accepting of host key for "
805: "loopback/localhost.");
1.108 markus 806: return 0;
1.49 markus 807: }
1.42 markus 808:
809: /*
1.229 djm 810: * Prepare the hostname and address strings used for hostkey lookup.
811: * In some cases, these will have a port number appended.
1.42 markus 812: */
1.229 djm 813: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 814:
815: /*
1.88 markus 816: * Turn off check_host_ip if the connection is to localhost, via proxy
817: * command or if we don't have a hostname to compare with
818: */
1.189 dtucker 819: if (options.check_host_ip && (local ||
820: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 821: options.check_host_ip = 0;
1.86 markus 822:
1.229 djm 823: host_hostkeys = init_hostkeys();
1.234 djm 824: for (i = 0; i < num_user_hostfiles; i++)
825: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
826: for (i = 0; i < num_system_hostfiles; i++)
827: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 828:
829: ip_hostkeys = NULL;
830: if (!want_cert && options.check_host_ip) {
831: ip_hostkeys = init_hostkeys();
1.234 djm 832: for (i = 0; i < num_user_hostfiles; i++)
833: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
834: for (i = 0; i < num_system_hostfiles; i++)
835: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 836: }
1.38 markus 837:
1.219 djm 838: retry:
1.229 djm 839: /* Reload these as they may have changed on cert->key downgrade */
1.219 djm 840: want_cert = key_is_cert(host_key);
841: type = key_type(host_key);
842:
1.46 markus 843: /*
1.170 djm 844: * Check if the host key is present in the user's list of known
1.40 markus 845: * hosts or in the systemwide list.
846: */
1.229 djm 847: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
848: &host_found);
849:
1.40 markus 850: /*
851: * Also perform check for the ip address, skip the check if we are
1.219 djm 852: * localhost, looking for a certificate, or the hostname was an ip
853: * address to begin with.
1.40 markus 854: */
1.229 djm 855: if (!want_cert && ip_hostkeys != NULL) {
856: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
857: &ip_found);
1.38 markus 858: if (host_status == HOST_CHANGED &&
1.229 djm 859: (ip_status != HOST_CHANGED ||
860: (ip_found != NULL &&
861: !key_equal(ip_found->key, host_found->key))))
1.38 markus 862: host_ip_differ = 1;
863: } else
864: ip_status = host_status;
865:
866: switch (host_status) {
867: case HOST_OK:
868: /* The host is known and the key matches. */
1.219 djm 869: debug("Host '%.200s' is known and matches the %s host %s.",
870: host, type, want_cert ? "certificate" : "key");
1.229 djm 871: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
872: host_found->file, host_found->line);
1.219 djm 873: if (want_cert && !check_host_cert(hostname, host_key))
874: goto fail;
1.88 markus 875: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 876: if (readonly || want_cert)
1.138 itojun 877: logit("%s host key for IP address "
1.108 markus 878: "'%.128s' not in list of known hosts.",
879: type, ip);
1.234 djm 880: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 881: host_key, options.hash_known_hosts))
1.138 itojun 882: logit("Failed to add the %s host key for IP "
1.108 markus 883: "address '%.128s' to the list of known "
1.234 djm 884: "hosts (%.30s).", type, ip,
885: user_hostfiles[0]);
1.88 markus 886: else
1.138 itojun 887: logit("Warning: Permanently added the %s host "
1.108 markus 888: "key for IP address '%.128s' to the list "
889: "of known hosts.", type, ip);
1.209 grunk 890: } else if (options.visual_host_key) {
1.204 grunk 891: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
892: ra = key_fingerprint(host_key, SSH_FP_MD5,
893: SSH_FP_RANDOMART);
894: logit("Host key fingerprint is %s\n%s\n", fp, ra);
1.238 djm 895: free(ra);
896: free(fp);
1.38 markus 897: }
898: break;
899: case HOST_NEW:
1.197 dtucker 900: if (options.host_key_alias == NULL && port != 0 &&
901: port != SSH_DEFAULT_PORT) {
902: debug("checking without port identifier");
1.212 stevesk 903: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 904: ROQUIET, user_hostfiles, num_user_hostfiles,
905: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 906: debug("found matching key w/out port");
907: break;
908: }
909: }
1.219 djm 910: if (readonly || want_cert)
1.108 markus 911: goto fail;
1.38 markus 912: /* The host is new. */
913: if (options.strict_host_key_checking == 1) {
1.108 markus 914: /*
915: * User has requested strict host key checking. We
916: * will not add the host key automatically. The only
917: * alternative left is to abort.
918: */
919: error("No %s host key is known for %.200s and you "
920: "have requested strict checking.", type, host);
921: goto fail;
1.38 markus 922: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 923: char msg1[1024], msg2[1024];
924:
1.229 djm 925: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 926: snprintf(msg1, sizeof(msg1),
1.168 djm 927: "\nbut keys of different type are already"
928: " known for this host.");
1.145 jakob 929: else
930: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 931: /* The default */
1.100 markus 932: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.204 grunk 933: ra = key_fingerprint(host_key, SSH_FP_MD5,
934: SSH_FP_RANDOMART);
1.145 jakob 935: msg2[0] = '\0';
936: if (options.verify_host_key_dns) {
1.153 jakob 937: if (matching_host_key_dns)
1.145 jakob 938: snprintf(msg2, sizeof(msg2),
939: "Matching host key fingerprint"
940: " found in DNS.\n");
941: else
942: snprintf(msg2, sizeof(msg2),
943: "No matching host key fingerprint"
944: " found in DNS.\n");
945: }
1.119 markus 946: snprintf(msg, sizeof(msg),
1.108 markus 947: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 948: "established%s\n"
1.209 grunk 949: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 950: "Are you sure you want to continue connecting "
1.132 markus 951: "(yes/no)? ",
1.209 grunk 952: host, ip, msg1, type, fp,
953: options.visual_host_key ? "\n" : "",
954: options.visual_host_key ? ra : "",
955: msg2);
1.238 djm 956: free(ra);
957: free(fp);
1.119 markus 958: if (!confirm(msg))
1.108 markus 959: goto fail;
1.38 markus 960: }
1.161 djm 961: /*
962: * If not in strict mode, add the key automatically to the
963: * local known_hosts file.
964: */
1.88 markus 965: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 966: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 967: hostp = hostline;
1.161 djm 968: if (options.hash_known_hosts) {
969: /* Add hash of host and IP separately */
1.234 djm 970: r = add_host_to_hostfile(user_hostfiles[0],
971: host, host_key, options.hash_known_hosts) &&
972: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 973: host_key, options.hash_known_hosts);
974: } else {
975: /* Add unhashed "host,ip" */
1.234 djm 976: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 977: hostline, host_key,
978: options.hash_known_hosts);
979: }
980: } else {
1.234 djm 981: r = add_host_to_hostfile(user_hostfiles[0], host,
982: host_key, options.hash_known_hosts);
1.38 markus 983: hostp = host;
1.161 djm 984: }
1.38 markus 985:
1.161 djm 986: if (!r)
1.138 itojun 987: logit("Failed to add the host to the list of known "
1.234 djm 988: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 989: else
1.138 itojun 990: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 991: "list of known hosts.", hostp, type);
1.38 markus 992: break;
1.220 djm 993: case HOST_REVOKED:
994: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
995: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
996: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
997: error("The %s host key for %s is marked as revoked.", type, host);
998: error("This could mean that a stolen key is being used to");
999: error("impersonate this host.");
1000:
1001: /*
1002: * If strict host key checking is in use, the user will have
1003: * to edit the key manually and we can only abort.
1004: */
1005: if (options.strict_host_key_checking) {
1006: error("%s host key for %.200s was revoked and you have "
1007: "requested strict checking.", type, host);
1008: goto fail;
1009: }
1010: goto continue_unsafe;
1011:
1.38 markus 1012: case HOST_CHANGED:
1.219 djm 1013: if (want_cert) {
1014: /*
1015: * This is only a debug() since it is valid to have
1016: * CAs with wildcard DNS matches that don't match
1017: * all hosts that one might visit.
1018: */
1019: debug("Host certificate authority does not "
1.229 djm 1020: "match %s in %s:%lu", CA_MARKER,
1021: host_found->file, host_found->line);
1.219 djm 1022: goto fail;
1023: }
1.197 dtucker 1024: if (readonly == ROQUIET)
1025: goto fail;
1.38 markus 1026: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1027: char *key_msg;
1.38 markus 1028: if (ip_status == HOST_NEW)
1.158 avsm 1029: key_msg = "is unknown";
1.38 markus 1030: else if (ip_status == HOST_OK)
1.158 avsm 1031: key_msg = "is unchanged";
1.38 markus 1032: else
1.158 avsm 1033: key_msg = "has a different value";
1.38 markus 1034: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1035: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1036: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1037: error("The %s host key for %s has changed,", type, host);
1.208 ian 1038: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1039: error("%s. This could either mean that", key_msg);
1.38 markus 1040: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1041: error("and its host key have changed at the same time.");
1.88 markus 1042: if (ip_status != HOST_NEW)
1.229 djm 1043: error("Offending key for IP in %s:%lu",
1044: ip_found->file, ip_found->line);
1.38 markus 1045: }
1046: /* The host key has changed. */
1.150 jakob 1047: warn_changed_key(host_key);
1.38 markus 1048: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1049: user_hostfiles[0]);
1.229 djm 1050: error("Offending %s key in %s:%lu", key_type(host_found->key),
1051: host_found->file, host_found->line);
1.38 markus 1052:
1.40 markus 1053: /*
1054: * If strict host key checking is in use, the user will have
1055: * to edit the key manually and we can only abort.
1056: */
1.108 markus 1057: if (options.strict_host_key_checking) {
1058: error("%s host key for %.200s has changed and you have "
1059: "requested strict checking.", type, host);
1060: goto fail;
1061: }
1.38 markus 1062:
1.220 djm 1063: continue_unsafe:
1.40 markus 1064: /*
1065: * If strict host key checking has not been requested, allow
1.144 djm 1066: * the connection but without MITM-able authentication or
1.194 stevesk 1067: * forwarding.
1.40 markus 1068: */
1.38 markus 1069: if (options.password_authentication) {
1.108 markus 1070: error("Password authentication is disabled to avoid "
1071: "man-in-the-middle attacks.");
1.38 markus 1072: options.password_authentication = 0;
1.210 dtucker 1073: cancelled_forwarding = 1;
1.144 djm 1074: }
1075: if (options.kbd_interactive_authentication) {
1076: error("Keyboard-interactive authentication is disabled"
1077: " to avoid man-in-the-middle attacks.");
1078: options.kbd_interactive_authentication = 0;
1079: options.challenge_response_authentication = 0;
1.210 dtucker 1080: cancelled_forwarding = 1;
1.144 djm 1081: }
1082: if (options.challenge_response_authentication) {
1083: error("Challenge/response authentication is disabled"
1084: " to avoid man-in-the-middle attacks.");
1085: options.challenge_response_authentication = 0;
1.210 dtucker 1086: cancelled_forwarding = 1;
1.38 markus 1087: }
1088: if (options.forward_agent) {
1.108 markus 1089: error("Agent forwarding is disabled to avoid "
1090: "man-in-the-middle attacks.");
1.38 markus 1091: options.forward_agent = 0;
1.210 dtucker 1092: cancelled_forwarding = 1;
1.83 markus 1093: }
1094: if (options.forward_x11) {
1.108 markus 1095: error("X11 forwarding is disabled to avoid "
1096: "man-in-the-middle attacks.");
1.83 markus 1097: options.forward_x11 = 0;
1.210 dtucker 1098: cancelled_forwarding = 1;
1.83 markus 1099: }
1.108 markus 1100: if (options.num_local_forwards > 0 ||
1101: options.num_remote_forwards > 0) {
1102: error("Port forwarding is disabled to avoid "
1103: "man-in-the-middle attacks.");
1104: options.num_local_forwards =
1.118 deraadt 1105: options.num_remote_forwards = 0;
1.210 dtucker 1106: cancelled_forwarding = 1;
1.194 stevesk 1107: }
1108: if (options.tun_open != SSH_TUNMODE_NO) {
1109: error("Tunnel forwarding is disabled to avoid "
1110: "man-in-the-middle attacks.");
1111: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1112: cancelled_forwarding = 1;
1.38 markus 1113: }
1.210 dtucker 1114: if (options.exit_on_forward_failure && cancelled_forwarding)
1115: fatal("Error: forwarding disabled due to host key "
1116: "check failure");
1117:
1.40 markus 1118: /*
1119: * XXX Should permit the user to change to use the new id.
1120: * This could be done by converting the host key to an
1121: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1122: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1123: * accept the authentication.
1124: */
1.38 markus 1125: break;
1.132 markus 1126: case HOST_FOUND:
1127: fatal("internal error");
1128: break;
1.88 markus 1129: }
1130:
1131: if (options.check_host_ip && host_status != HOST_CHANGED &&
1132: ip_status == HOST_CHANGED) {
1.119 markus 1133: snprintf(msg, sizeof(msg),
1134: "Warning: the %s host key for '%.200s' "
1135: "differs from the key for the IP address '%.128s'"
1.229 djm 1136: "\nOffending key for IP in %s:%lu",
1137: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1138: if (host_status == HOST_OK) {
1139: len = strlen(msg);
1140: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1141: "\nMatching host key in %s:%lu",
1142: host_found->file, host_found->line);
1.119 markus 1143: }
1.88 markus 1144: if (options.strict_host_key_checking == 1) {
1.143 djm 1145: logit("%s", msg);
1.108 markus 1146: error("Exiting, you have requested strict checking.");
1147: goto fail;
1.88 markus 1148: } else if (options.strict_host_key_checking == 2) {
1.119 markus 1149: strlcat(msg, "\nAre you sure you want "
1150: "to continue connecting (yes/no)? ", sizeof(msg));
1151: if (!confirm(msg))
1.108 markus 1152: goto fail;
1.119 markus 1153: } else {
1.143 djm 1154: logit("%s", msg);
1.88 markus 1155: }
1.38 markus 1156: }
1.82 provos 1157:
1.238 djm 1158: free(ip);
1159: free(host);
1.229 djm 1160: if (host_hostkeys != NULL)
1161: free_hostkeys(host_hostkeys);
1162: if (ip_hostkeys != NULL)
1163: free_hostkeys(ip_hostkeys);
1.108 markus 1164: return 0;
1165:
1166: fail:
1.220 djm 1167: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1168: /*
1169: * No matching certificate. Downgrade cert to raw key and
1170: * search normally.
1171: */
1172: debug("No matching CA found. Retry with plain key");
1173: raw_key = key_from_private(host_key);
1174: if (key_drop_cert(raw_key) != 0)
1175: fatal("Couldn't drop certificate");
1176: host_key = raw_key;
1177: goto retry;
1178: }
1179: if (raw_key != NULL)
1180: key_free(raw_key);
1.238 djm 1181: free(ip);
1182: free(host);
1.229 djm 1183: if (host_hostkeys != NULL)
1184: free_hostkeys(host_hostkeys);
1185: if (ip_hostkeys != NULL)
1186: free_hostkeys(ip_hostkeys);
1.108 markus 1187: return -1;
1188: }
1189:
1.140 jakob 1190: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1191: int
1192: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1193: {
1.153 jakob 1194: int flags = 0;
1.229 djm 1195: char *fp;
1.247 djm 1196: Key *plain = NULL;
1.229 djm 1197:
1198: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1199: debug("Server host key: %s %s", key_type(host_key), fp);
1.238 djm 1200: free(fp);
1.140 jakob 1201:
1.247 djm 1202: if (options.verify_host_key_dns) {
1203: /*
1204: * XXX certs are not yet supported for DNS, so downgrade
1205: * them and try the plain key.
1206: */
1207: plain = key_from_private(host_key);
1208: if (key_is_cert(plain))
1209: key_drop_cert(plain);
1210: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1211: if (flags & DNS_VERIFY_FOUND) {
1212: if (options.verify_host_key_dns == 1 &&
1213: flags & DNS_VERIFY_MATCH &&
1214: flags & DNS_VERIFY_SECURE) {
1215: key_free(plain);
1216: return 0;
1217: }
1218: if (flags & DNS_VERIFY_MATCH) {
1219: matching_host_key_dns = 1;
1220: } else {
1221: warn_changed_key(plain);
1222: error("Update the SSHFP RR in DNS "
1223: "with the new host key to get rid "
1224: "of this message.");
1225: }
1.153 jakob 1226: }
1.140 jakob 1227: }
1.247 djm 1228: key_free(plain);
1.140 jakob 1229: }
1.108 markus 1230:
1.234 djm 1231: return check_host_key(host, hostaddr, options.port, host_key, RDRW,
1232: options.user_hostfiles, options.num_user_hostfiles,
1233: options.system_hostfiles, options.num_system_hostfiles);
1.51 markus 1234: }
1.70 markus 1235:
1.51 markus 1236: /*
1237: * Starts a dialog with the server, and authenticates the current user on the
1238: * server. This does not need any extra privileges. The basic connection
1239: * to the server must already have been established before this is called.
1240: * If login fails, this function prints an error and never returns.
1241: * This function does not require super-user privileges.
1242: */
1243: void
1.120 markus 1244: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1245: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1246: {
1.241 djm 1247: char *host;
1.70 markus 1248: char *server_user, *local_user;
1249:
1250: local_user = xstrdup(pw->pw_name);
1251: server_user = options.user ? options.user : local_user;
1.51 markus 1252:
1253: /* Convert the user-supplied hostname into all lowercase. */
1254: host = xstrdup(orighost);
1.241 djm 1255: lowercase(host);
1.51 markus 1256:
1257: /* Exchange protocol version identification strings with the server. */
1.202 djm 1258: ssh_exchange_identification(timeout_ms);
1.51 markus 1259:
1260: /* Put the connection into non-blocking mode. */
1261: packet_set_nonblocking();
1262:
1263: /* key exchange */
1264: /* authenticate user */
1.59 markus 1265: if (compat20) {
1.229 djm 1266: ssh_kex2(host, hostaddr, port);
1.120 markus 1267: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 1268: } else {
1.248 markus 1269: #ifdef WITH_SSH1
1.59 markus 1270: ssh_kex(host, hostaddr);
1.120 markus 1271: ssh_userauth1(local_user, server_user, host, sensitive);
1.248 markus 1272: #else
1273: fatal("ssh1 is not unsupported");
1274: #endif
1.59 markus 1275: }
1.238 djm 1276: free(local_user);
1.97 markus 1277: }
1278:
1279: void
1280: ssh_put_password(char *password)
1281: {
1282: int size;
1283: char *padded;
1284:
1.99 deraadt 1285: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1286: packet_put_cstring(password);
1.99 deraadt 1287: return;
1288: }
1.97 markus 1289: size = roundup(strlen(password) + 1, 32);
1.179 djm 1290: padded = xcalloc(1, size);
1.97 markus 1291: strlcpy(padded, password, size);
1292: packet_put_string(padded, size);
1.245 djm 1293: explicit_bzero(padded, size);
1.238 djm 1294: free(padded);
1.132 markus 1295: }
1296:
1297: /* print all known host keys for a given host, but skip keys of given type */
1298: static int
1.229 djm 1299: show_other_keys(struct hostkeys *hostkeys, Key *key)
1.132 markus 1300: {
1.242 djm 1301: int type[] = {
1302: KEY_RSA1,
1303: KEY_RSA,
1304: KEY_DSA,
1305: KEY_ECDSA,
1306: KEY_ED25519,
1307: -1
1308: };
1.229 djm 1309: int i, ret = 0;
1310: char *fp, *ra;
1311: const struct hostkey_entry *found;
1.132 markus 1312:
1313: for (i = 0; type[i] != -1; i++) {
1314: if (type[i] == key->type)
1315: continue;
1.229 djm 1316: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1317: continue;
1.229 djm 1318: fp = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_HEX);
1319: ra = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_RANDOMART);
1320: logit("WARNING: %s key found for host %s\n"
1321: "in %s:%lu\n"
1322: "%s key fingerprint %s.",
1323: key_type(found->key),
1324: found->host, found->file, found->line,
1325: key_type(found->key), fp);
1326: if (options.visual_host_key)
1327: logit("%s", ra);
1.238 djm 1328: free(ra);
1329: free(fp);
1.229 djm 1330: ret = 1;
1.132 markus 1331: }
1.229 djm 1332: return ret;
1.150 jakob 1333: }
1334:
1335: static void
1336: warn_changed_key(Key *host_key)
1337: {
1338: char *fp;
1339:
1340: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1341:
1342: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1343: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1344: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1345: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1346: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1347: error("It is also possible that a host key has just been changed.");
1.150 jakob 1348: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.230 markus 1349: key_type(host_key), fp);
1.150 jakob 1350: error("Please contact your system administrator.");
1351:
1.238 djm 1352: free(fp);
1.171 reyk 1353: }
1354:
1355: /*
1356: * Execute a local command
1357: */
1358: int
1359: ssh_local_cmd(const char *args)
1360: {
1361: char *shell;
1362: pid_t pid;
1363: int status;
1.231 djm 1364: void (*osighand)(int);
1.171 reyk 1365:
1366: if (!options.permit_local_command ||
1367: args == NULL || !*args)
1368: return (1);
1369:
1.226 djm 1370: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1371: shell = _PATH_BSHELL;
1372:
1.231 djm 1373: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1374: pid = fork();
1375: if (pid == 0) {
1.232 djm 1376: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1377: debug3("Executing %s -c \"%s\"", shell, args);
1378: execl(shell, shell, "-c", args, (char *)NULL);
1379: error("Couldn't execute %s -c \"%s\": %s",
1380: shell, args, strerror(errno));
1381: _exit(1);
1382: } else if (pid == -1)
1383: fatal("fork failed: %.100s", strerror(errno));
1384: while (waitpid(pid, &status, 0) == -1)
1385: if (errno != EINTR)
1386: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1387: signal(SIGCHLD, osighand);
1.171 reyk 1388:
1389: if (!WIFEXITED(status))
1390: return (1);
1391:
1392: return (WEXITSTATUS(status));
1.1 deraadt 1393: }
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