Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.267
1.267 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.266 2015/11/15 22:26:49 jcs 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:
1.256 deraadt 16: #include <sys/param.h> /* roundup */
1.174 stevesk 17: #include <sys/types.h>
18: #include <sys/wait.h>
1.175 stevesk 19: #include <sys/stat.h>
1.187 stevesk 20: #include <sys/socket.h>
1.195 stevesk 21: #include <sys/time.h>
1.187 stevesk 22:
23: #include <netinet/in.h>
1.172 stevesk 24:
1.176 stevesk 25: #include <ctype.h>
1.190 stevesk 26: #include <errno.h>
1.216 dtucker 27: #include <fcntl.h>
1.191 stevesk 28: #include <netdb.h>
1.172 stevesk 29: #include <paths.h>
1.199 deraadt 30: #include <signal.h>
1.188 stevesk 31: #include <pwd.h>
1.198 stevesk 32: #include <stdio.h>
1.196 stevesk 33: #include <stdlib.h>
1.193 stevesk 34: #include <string.h>
1.192 stevesk 35: #include <unistd.h>
1.71 markus 36:
1.199 deraadt 37: #include "xmalloc.h"
1.91 markus 38: #include "ssh.h"
1.1 deraadt 39: #include "rsa.h"
1.59 markus 40: #include "buffer.h"
1.1 deraadt 41: #include "packet.h"
42: #include "uidswap.h"
1.21 markus 43: #include "compat.h"
1.58 markus 44: #include "key.h"
1.71 markus 45: #include "sshconnect.h"
1.58 markus 46: #include "hostfile.h"
1.91 markus 47: #include "log.h"
1.251 millert 48: #include "misc.h"
1.91 markus 49: #include "readconf.h"
50: #include "atomicio.h"
1.140 jakob 51: #include "dns.h"
1.214 andreas 52: #include "roaming.h"
1.239 djm 53: #include "monitor_fdpass.h"
1.219 djm 54: #include "ssh2.h"
1.186 stevesk 55: #include "version.h"
1.252 djm 56: #include "authfile.h"
57: #include "ssherr.h"
1.266 jcs 58: #include "authfd.h"
1.140 jakob 59:
1.70 markus 60: char *client_version_string = NULL;
61: char *server_version_string = NULL;
1.250 djm 62: Key *previous_host_key = NULL;
1.59 markus 63:
1.169 stevesk 64: static int matching_host_key_dns = 0;
1.145 jakob 65:
1.227 djm 66: static pid_t proxy_command_pid = 0;
67:
1.124 markus 68: /* import */
1.43 markus 69: extern Options options;
1.50 markus 70: extern char *__progname;
1.124 markus 71: extern uid_t original_real_uid;
72: extern uid_t original_effective_uid;
1.91 markus 73:
1.229 djm 74: static int show_other_keys(struct hostkeys *, Key *);
1.150 jakob 75: static void warn_changed_key(Key *);
1.132 markus 76:
1.239 djm 77: /* Expand a proxy command */
78: static char *
79: expand_proxy_command(const char *proxy_command, const char *user,
80: const char *host, int port)
81: {
82: char *tmp, *ret, strport[NI_MAXSERV];
83:
1.241 djm 84: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 85: xasprintf(&tmp, "exec %s", proxy_command);
86: ret = percent_expand(tmp, "h", host, "p", strport,
87: "r", options.user, (char *)NULL);
88: free(tmp);
89: return ret;
90: }
91:
92: /*
93: * Connect to the given ssh server using a proxy command that passes a
94: * a connected fd back to us.
95: */
96: static int
97: ssh_proxy_fdpass_connect(const char *host, u_short port,
98: const char *proxy_command)
99: {
100: char *command_string;
101: int sp[2], sock;
102: pid_t pid;
103: char *shell;
104:
105: if ((shell = getenv("SHELL")) == NULL)
106: shell = _PATH_BSHELL;
107:
108: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
109: fatal("Could not create socketpair to communicate with "
110: "proxy dialer: %.100s", strerror(errno));
111:
112: command_string = expand_proxy_command(proxy_command, options.user,
113: host, port);
114: debug("Executing proxy dialer command: %.500s", command_string);
115:
116: /* Fork and execute the proxy command. */
117: if ((pid = fork()) == 0) {
118: char *argv[10];
119:
120: /* Child. Permanently give up superuser privileges. */
121: permanently_drop_suid(original_real_uid);
122:
123: close(sp[1]);
124: /* Redirect stdin and stdout. */
125: if (sp[0] != 0) {
126: if (dup2(sp[0], 0) < 0)
127: perror("dup2 stdin");
128: }
129: if (sp[0] != 1) {
130: if (dup2(sp[0], 1) < 0)
131: perror("dup2 stdout");
132: }
133: if (sp[0] >= 2)
134: close(sp[0]);
135:
136: /*
137: * Stderr is left as it is so that error messages get
138: * printed on the user's terminal.
139: */
140: argv[0] = shell;
141: argv[1] = "-c";
142: argv[2] = command_string;
143: argv[3] = NULL;
144:
145: /*
146: * Execute the proxy command.
147: * Note that we gave up any extra privileges above.
148: */
149: execv(argv[0], argv);
150: perror(argv[0]);
151: exit(1);
152: }
153: /* Parent. */
154: if (pid < 0)
155: fatal("fork failed: %.100s", strerror(errno));
156: close(sp[0]);
157: free(command_string);
158:
159: if ((sock = mm_receive_fd(sp[1])) == -1)
160: fatal("proxy dialer did not pass back a connection");
161:
162: while (waitpid(pid, NULL, 0) == -1)
163: if (errno != EINTR)
164: fatal("Couldn't wait for child: %s", strerror(errno));
165:
166: /* Set the connection file descriptors. */
167: packet_set_connection(sock, sock);
168:
169: return 0;
170: }
171:
1.39 deraadt 172: /*
173: * Connect to the given ssh server using a proxy command.
174: */
1.109 itojun 175: static int
1.124 markus 176: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 177: {
1.239 djm 178: char *command_string;
1.38 markus 179: int pin[2], pout[2];
1.69 deraadt 180: pid_t pid;
1.239 djm 181: char *shell;
1.237 markus 182:
1.226 djm 183: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 184: shell = _PATH_BSHELL;
1.38 markus 185:
186: /* Create pipes for communicating with the proxy. */
187: if (pipe(pin) < 0 || pipe(pout) < 0)
188: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 189: strerror(errno));
1.38 markus 190:
1.239 djm 191: command_string = expand_proxy_command(proxy_command, options.user,
192: host, port);
1.38 markus 193: debug("Executing proxy command: %.500s", command_string);
194:
195: /* Fork and execute the proxy command. */
196: if ((pid = fork()) == 0) {
197: char *argv[10];
198:
199: /* Child. Permanently give up superuser privileges. */
1.184 markus 200: permanently_drop_suid(original_real_uid);
1.38 markus 201:
202: /* Redirect stdin and stdout. */
203: close(pin[1]);
204: if (pin[0] != 0) {
205: if (dup2(pin[0], 0) < 0)
206: perror("dup2 stdin");
207: close(pin[0]);
208: }
209: close(pout[0]);
210: if (dup2(pout[1], 1) < 0)
211: perror("dup2 stdout");
212: /* Cannot be 1 because pin allocated two descriptors. */
213: close(pout[1]);
214:
215: /* Stderr is left as it is so that error messages get
216: printed on the user's terminal. */
1.201 djm 217: argv[0] = shell;
1.38 markus 218: argv[1] = "-c";
219: argv[2] = command_string;
220: argv[3] = NULL;
221:
222: /* Execute the proxy command. Note that we gave up any
223: extra privileges above. */
1.232 djm 224: signal(SIGPIPE, SIG_DFL);
1.89 markus 225: execv(argv[0], argv);
226: perror(argv[0]);
1.38 markus 227: exit(1);
228: }
229: /* Parent. */
230: if (pid < 0)
231: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 232: else
233: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 234:
235: /* Close child side of the descriptors. */
236: close(pin[0]);
237: close(pout[1]);
238:
239: /* Free the command name. */
1.238 djm 240: free(command_string);
1.38 markus 241:
242: /* Set the connection file descriptors. */
243: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 244:
1.110 markus 245: /* Indicate OK return */
246: return 0;
1.227 djm 247: }
248:
249: void
250: ssh_kill_proxy_command(void)
251: {
252: /*
253: * Send SIGHUP to proxy command if used. We don't wait() in
254: * case it hangs and instead rely on init to reap the child
255: */
256: if (proxy_command_pid > 1)
1.228 djm 257: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 258: }
259:
1.39 deraadt 260: /*
261: * Creates a (possibly privileged) socket for use as the ssh connection.
262: */
1.109 itojun 263: static int
1.139 markus 264: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 265: {
1.240 djm 266: int sock, r, gaierr;
1.246 djm 267: struct addrinfo hints, *res = NULL;
1.1 deraadt 268:
1.217 dtucker 269: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 270: if (sock < 0) {
1.240 djm 271: error("socket: %s", strerror(errno));
1.216 dtucker 272: return -1;
273: }
274: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 275:
276: /* Bind the socket to an alternative local IP address */
1.240 djm 277: if (options.bind_address == NULL && !privileged)
1.105 markus 278: return sock;
279:
1.246 djm 280: if (options.bind_address) {
281: memset(&hints, 0, sizeof(hints));
282: hints.ai_family = ai->ai_family;
283: hints.ai_socktype = ai->ai_socktype;
284: hints.ai_protocol = ai->ai_protocol;
285: hints.ai_flags = AI_PASSIVE;
286: gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
287: if (gaierr) {
288: error("getaddrinfo: %s: %s", options.bind_address,
289: ssh_gai_strerror(gaierr));
290: close(sock);
291: return -1;
292: }
1.105 markus 293: }
1.240 djm 294: /*
295: * If we are running as root and want to connect to a privileged
296: * port, bind our own socket to a privileged port.
297: */
298: if (privileged) {
299: PRIV_START;
1.246 djm 300: r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
1.240 djm 301: PRIV_END;
302: if (r < 0) {
303: error("bindresvport_sa: af=%d %s", ai->ai_family,
304: strerror(errno));
305: goto fail;
306: }
307: } else {
308: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
309: error("bind: %s: %s", options.bind_address,
310: strerror(errno));
311: fail:
312: close(sock);
313: freeaddrinfo(res);
314: return -1;
315: }
1.38 markus 316: }
1.246 djm 317: if (res != NULL)
318: freeaddrinfo(res);
1.38 markus 319: return sock;
1.1 deraadt 320: }
321:
1.141 djm 322: static int
323: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 324: socklen_t addrlen, int *timeoutp)
1.141 djm 325: {
326: fd_set *fdset;
1.202 djm 327: struct timeval tv, t_start;
1.141 djm 328: socklen_t optlen;
1.179 djm 329: int optval, rc, result = -1;
1.141 djm 330:
1.202 djm 331: gettimeofday(&t_start, NULL);
332:
333: if (*timeoutp <= 0) {
334: result = connect(sockfd, serv_addr, addrlen);
335: goto done;
336: }
1.141 djm 337:
1.156 djm 338: set_nonblock(sockfd);
1.141 djm 339: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 340: if (rc == 0) {
341: unset_nonblock(sockfd);
1.202 djm 342: result = 0;
343: goto done;
344: }
345: if (errno != EINPROGRESS) {
346: result = -1;
347: goto done;
1.156 djm 348: }
1.141 djm 349:
1.263 deraadt 350: fdset = xcalloc(howmany(sockfd + 1, NFDBITS),
1.179 djm 351: sizeof(fd_mask));
1.141 djm 352: FD_SET(sockfd, fdset);
1.202 djm 353: ms_to_timeval(&tv, *timeoutp);
1.141 djm 354:
1.162 deraadt 355: for (;;) {
1.141 djm 356: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
357: if (rc != -1 || errno != EINTR)
358: break;
359: }
360:
1.162 deraadt 361: switch (rc) {
1.141 djm 362: case 0:
363: /* Timed out */
364: errno = ETIMEDOUT;
1.142 djm 365: break;
1.141 djm 366: case -1:
367: /* Select error */
1.154 djm 368: debug("select: %s", strerror(errno));
1.142 djm 369: break;
1.141 djm 370: case 1:
371: /* Completed or failed */
372: optval = 0;
373: optlen = sizeof(optval);
1.154 djm 374: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 375: &optlen) == -1) {
1.154 djm 376: debug("getsockopt: %s", strerror(errno));
1.142 djm 377: break;
1.148 markus 378: }
1.141 djm 379: if (optval != 0) {
380: errno = optval;
1.142 djm 381: break;
1.141 djm 382: }
1.142 djm 383: result = 0;
1.156 djm 384: unset_nonblock(sockfd);
1.141 djm 385: break;
386: default:
387: /* Should not occur */
388: fatal("Bogus return (%d) from select()", rc);
389: }
390:
1.238 djm 391: free(fdset);
1.202 djm 392:
393: done:
394: if (result == 0 && *timeoutp > 0) {
395: ms_subtract_diff(&t_start, timeoutp);
396: if (*timeoutp <= 0) {
397: errno = ETIMEDOUT;
398: result = -1;
399: }
400: }
401:
1.142 djm 402: return (result);
1.141 djm 403: }
404:
1.39 deraadt 405: /*
1.49 markus 406: * Opens a TCP/IP connection to the remote server on the given host.
407: * The address of the remote host will be returned in hostaddr.
1.124 markus 408: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 409: * a privileged port will be allocated to make the connection.
1.124 markus 410: * This requires super-user privileges if needpriv is true.
1.39 deraadt 411: * Connection_attempts specifies the maximum number of tries (one per
412: * second). If proxy_command is non-NULL, it specifies the command (with %h
413: * and %p substituted for host and port, respectively) to use to contact
414: * the daemon.
415: */
1.241 djm 416: static int
417: ssh_connect_direct(const char *host, struct addrinfo *aitop,
418: struct sockaddr_storage *hostaddr, u_short port, int family,
419: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
1.1 deraadt 420: {
1.90 markus 421: int on = 1;
1.49 markus 422: int sock = -1, attempt;
1.90 markus 423: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 424: struct addrinfo *ai;
1.38 markus 425:
1.265 djm 426: debug2("%s: needpriv %d", __func__, needpriv);
1.38 markus 427:
1.181 markus 428: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 429: if (attempt > 0) {
430: /* Sleep a moment before retrying. */
431: sleep(1);
1.38 markus 432: debug("Trying again...");
1.200 markus 433: }
1.181 markus 434: /*
435: * Loop through addresses for this host, and try each one in
436: * sequence until the connection succeeds.
437: */
1.49 markus 438: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 439: if (ai->ai_family != AF_INET &&
440: ai->ai_family != AF_INET6)
1.49 markus 441: continue;
442: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
443: ntop, sizeof(ntop), strport, sizeof(strport),
444: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.265 djm 445: error("%s: getnameinfo failed", __func__);
1.49 markus 446: continue;
447: }
448: debug("Connecting to %.200s [%.100s] port %s.",
449: host, ntop, strport);
450:
451: /* Create a socket for connecting. */
1.139 markus 452: sock = ssh_create_socket(needpriv, ai);
1.49 markus 453: if (sock < 0)
1.110 markus 454: /* Any error is already output */
1.49 markus 455: continue;
456:
1.141 djm 457: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 458: timeout_ms) >= 0) {
1.49 markus 459: /* Successful connection. */
1.102 markus 460: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 461: break;
1.49 markus 462: } else {
1.131 itojun 463: debug("connect to address %s port %s: %s",
464: ntop, strport, strerror(errno));
1.38 markus 465: close(sock);
1.181 markus 466: sock = -1;
1.38 markus 467: }
468: }
1.181 markus 469: if (sock != -1)
1.49 markus 470: break; /* Successful connection. */
1.38 markus 471: }
1.49 markus 472:
1.38 markus 473: /* Return failure if we didn't get a successful connection. */
1.181 markus 474: if (sock == -1) {
1.159 markus 475: error("ssh: connect to host %s port %s: %s",
1.130 itojun 476: host, strport, strerror(errno));
1.159 markus 477: return (-1);
1.130 itojun 478: }
1.38 markus 479:
480: debug("Connection established.");
1.90 markus 481:
1.155 markus 482: /* Set SO_KEEPALIVE if requested. */
1.202 djm 483: if (want_keepalive &&
1.90 markus 484: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
485: sizeof(on)) < 0)
486: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 487:
488: /* Set the connection. */
489: packet_set_connection(sock, sock);
1.1 deraadt 490:
1.110 markus 491: return 0;
1.59 markus 492: }
493:
1.241 djm 494: int
495: ssh_connect(const char *host, struct addrinfo *addrs,
496: struct sockaddr_storage *hostaddr, u_short port, int family,
497: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
498: {
499: if (options.proxy_command == NULL) {
500: return ssh_connect_direct(host, addrs, hostaddr, port, family,
501: connection_attempts, timeout_ms, want_keepalive, needpriv);
502: } else if (strcmp(options.proxy_command, "-") == 0) {
503: packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
504: return 0; /* Always succeeds */
505: } else if (options.proxy_use_fdpass) {
506: return ssh_proxy_fdpass_connect(host, port,
507: options.proxy_command);
508: }
509: return ssh_proxy_connect(host, port, options.proxy_command);
510: }
511:
1.235 djm 512: static void
513: send_client_banner(int connection_out, int minor1)
514: {
515: /* Send our own protocol version identification. */
516: if (compat20) {
517: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
518: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
519: } else {
520: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n",
521: PROTOCOL_MAJOR_1, minor1, SSH_VERSION);
522: }
523: if (roaming_atomicio(vwrite, connection_out, client_version_string,
524: strlen(client_version_string)) != strlen(client_version_string))
525: fatal("write: %.100s", strerror(errno));
526: chop(client_version_string);
527: debug("Local version string %.100s", client_version_string);
528: }
529:
1.43 markus 530: /*
1.39 deraadt 531: * Waits for the server identification string, and sends our own
532: * identification string.
533: */
1.213 andreas 534: void
1.202 djm 535: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 536: {
1.38 markus 537: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 538: int remote_major, remote_minor, mismatch;
1.38 markus 539: int connection_in = packet_get_connection_in();
540: int connection_out = packet_get_connection_out();
1.235 djm 541: int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
1.185 djm 542: u_int i, n;
1.202 djm 543: size_t len;
544: int fdsetsz, remaining, rc;
545: struct timeval t_start, t_remaining;
546: fd_set *fdset;
547:
548: fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
549: fdset = xcalloc(1, fdsetsz);
1.38 markus 550:
1.235 djm 551: /*
552: * If we are SSH2-only then we can send the banner immediately and
553: * save a round-trip.
554: */
555: if (options.protocol == SSH_PROTO_2) {
556: enable_compat20();
557: send_client_banner(connection_out, 0);
558: client_banner_sent = 1;
559: }
560:
1.163 avsm 561: /* Read other side's version identification. */
1.202 djm 562: remaining = timeout_ms;
1.185 djm 563: for (n = 0;;) {
1.75 markus 564: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 565: if (timeout_ms > 0) {
566: gettimeofday(&t_start, NULL);
567: ms_to_timeval(&t_remaining, remaining);
568: FD_SET(connection_in, fdset);
569: rc = select(connection_in + 1, fdset, NULL,
570: fdset, &t_remaining);
571: ms_subtract_diff(&t_start, &remaining);
572: if (rc == 0 || remaining <= 0)
573: fatal("Connection timed out during "
574: "banner exchange");
575: if (rc == -1) {
576: if (errno == EINTR)
577: continue;
578: fatal("ssh_exchange_identification: "
579: "select: %s", strerror(errno));
580: }
581: }
582:
1.214 andreas 583: len = roaming_atomicio(read, connection_in, &buf[i], 1);
1.163 avsm 584:
1.167 djm 585: if (len != 1 && errno == EPIPE)
1.202 djm 586: fatal("ssh_exchange_identification: "
587: "Connection closed by remote host");
1.163 avsm 588: else if (len != 1)
1.202 djm 589: fatal("ssh_exchange_identification: "
590: "read: %.100s", strerror(errno));
1.75 markus 591: if (buf[i] == '\r') {
592: buf[i] = '\n';
593: buf[i + 1] = 0;
594: continue; /**XXX wait for \n */
595: }
596: if (buf[i] == '\n') {
597: buf[i + 1] = 0;
598: break;
599: }
1.185 djm 600: if (++n > 65536)
1.202 djm 601: fatal("ssh_exchange_identification: "
602: "No banner received");
1.38 markus 603: }
1.75 markus 604: buf[sizeof(buf) - 1] = 0;
1.76 markus 605: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 606: break;
1.75 markus 607: debug("ssh_exchange_identification: %s", buf);
1.38 markus 608: }
1.59 markus 609: server_version_string = xstrdup(buf);
1.238 djm 610: free(fdset);
1.38 markus 611:
1.40 markus 612: /*
613: * Check that the versions match. In future this might accept
614: * several versions and set appropriate flags to handle them.
615: */
1.59 markus 616: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
617: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 618: fatal("Bad remote protocol version identification: '%.100s'", buf);
619: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 620: remote_major, remote_minor, remote_version);
1.38 markus 621:
1.255 markus 622: active_state->compat = compat_datafellows(remote_version);
1.64 markus 623: mismatch = 0;
1.59 markus 624:
1.116 deraadt 625: switch (remote_major) {
1.64 markus 626: case 1:
627: if (remote_minor == 99 &&
628: (options.protocol & SSH_PROTO_2) &&
629: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
630: enable_compat20();
631: break;
632: }
633: if (!(options.protocol & SSH_PROTO_1)) {
634: mismatch = 1;
635: break;
636: }
637: if (remote_minor < 3) {
638: fatal("Remote machine has too old SSH software version.");
1.81 markus 639: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 640: /* We speak 1.3, too. */
641: enable_compat13();
1.81 markus 642: minor1 = 3;
1.64 markus 643: if (options.forward_agent) {
1.138 itojun 644: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 645: options.forward_agent = 0;
646: }
647: }
648: break;
649: case 2:
650: if (options.protocol & SSH_PROTO_2) {
651: enable_compat20();
652: break;
1.38 markus 653: }
1.64 markus 654: /* FALLTHROUGH */
1.68 markus 655: default:
1.64 markus 656: mismatch = 1;
657: break;
1.38 markus 658: }
1.64 markus 659: if (mismatch)
1.38 markus 660: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 661: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
662: remote_major);
1.244 djm 663: if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
664: fatal("Server version \"%.100s\" uses unsafe key agreement; "
665: "refusing connection", remote_version);
1.243 djm 666: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
667: logit("Server version \"%.100s\" uses unsafe RSA signature "
668: "scheme; disabling use of RSA keys", remote_version);
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: }
1.249 djm 707: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 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)
1.259 djm 748: fatal("%s: getnameinfo failed", __func__);
1.229 djm 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;
1.257 djm 796: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 797: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 798: u_int i;
1.49 markus 799:
800: /*
801: * Force accepting of the host key for loopback/localhost. The
802: * problem is that if the home directory is NFS-mounted to multiple
803: * machines, localhost will refer to a different machine in each of
804: * them, and the user will get bogus HOST_CHANGED warnings. This
805: * essentially disables host authentication for localhost; however,
806: * this is probably not a real problem.
807: */
1.111 markus 808: if (options.no_host_authentication_for_localhost == 1 && local &&
809: options.host_key_alias == NULL) {
1.88 markus 810: debug("Forcing accepting of host key for "
811: "loopback/localhost.");
1.108 markus 812: return 0;
1.49 markus 813: }
1.42 markus 814:
815: /*
1.229 djm 816: * Prepare the hostname and address strings used for hostkey lookup.
817: * In some cases, these will have a port number appended.
1.42 markus 818: */
1.229 djm 819: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 820:
821: /*
1.88 markus 822: * Turn off check_host_ip if the connection is to localhost, via proxy
823: * command or if we don't have a hostname to compare with
824: */
1.189 dtucker 825: if (options.check_host_ip && (local ||
826: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 827: options.check_host_ip = 0;
1.86 markus 828:
1.229 djm 829: host_hostkeys = init_hostkeys();
1.234 djm 830: for (i = 0; i < num_user_hostfiles; i++)
831: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
832: for (i = 0; i < num_system_hostfiles; i++)
833: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 834:
835: ip_hostkeys = NULL;
836: if (!want_cert && options.check_host_ip) {
837: ip_hostkeys = init_hostkeys();
1.234 djm 838: for (i = 0; i < num_user_hostfiles; i++)
839: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
840: for (i = 0; i < num_system_hostfiles; i++)
841: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 842: }
1.38 markus 843:
1.219 djm 844: retry:
1.229 djm 845: /* Reload these as they may have changed on cert->key downgrade */
1.219 djm 846: want_cert = key_is_cert(host_key);
847: type = key_type(host_key);
848:
1.46 markus 849: /*
1.170 djm 850: * Check if the host key is present in the user's list of known
1.40 markus 851: * hosts or in the systemwide list.
852: */
1.229 djm 853: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
854: &host_found);
855:
1.40 markus 856: /*
857: * Also perform check for the ip address, skip the check if we are
1.219 djm 858: * localhost, looking for a certificate, or the hostname was an ip
859: * address to begin with.
1.40 markus 860: */
1.229 djm 861: if (!want_cert && ip_hostkeys != NULL) {
862: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
863: &ip_found);
1.38 markus 864: if (host_status == HOST_CHANGED &&
1.229 djm 865: (ip_status != HOST_CHANGED ||
866: (ip_found != NULL &&
867: !key_equal(ip_found->key, host_found->key))))
1.38 markus 868: host_ip_differ = 1;
869: } else
870: ip_status = host_status;
871:
872: switch (host_status) {
873: case HOST_OK:
874: /* The host is known and the key matches. */
1.219 djm 875: debug("Host '%.200s' is known and matches the %s host %s.",
876: host, type, want_cert ? "certificate" : "key");
1.229 djm 877: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
878: host_found->file, host_found->line);
1.219 djm 879: if (want_cert && !check_host_cert(hostname, host_key))
880: goto fail;
1.88 markus 881: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 882: if (readonly || want_cert)
1.138 itojun 883: logit("%s host key for IP address "
1.108 markus 884: "'%.128s' not in list of known hosts.",
885: type, ip);
1.234 djm 886: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 887: host_key, options.hash_known_hosts))
1.138 itojun 888: logit("Failed to add the %s host key for IP "
1.108 markus 889: "address '%.128s' to the list of known "
1.262 dtucker 890: "hosts (%.500s).", type, ip,
1.234 djm 891: user_hostfiles[0]);
1.88 markus 892: else
1.138 itojun 893: logit("Warning: Permanently added the %s host "
1.108 markus 894: "key for IP address '%.128s' to the list "
895: "of known hosts.", type, ip);
1.209 grunk 896: } else if (options.visual_host_key) {
1.259 djm 897: fp = sshkey_fingerprint(host_key,
1.254 djm 898: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 899: ra = sshkey_fingerprint(host_key,
1.254 djm 900: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 901: if (fp == NULL || ra == NULL)
902: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 903: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 904: free(ra);
905: free(fp);
1.38 markus 906: }
1.257 djm 907: hostkey_trusted = 1;
1.38 markus 908: break;
909: case HOST_NEW:
1.197 dtucker 910: if (options.host_key_alias == NULL && port != 0 &&
911: port != SSH_DEFAULT_PORT) {
912: debug("checking without port identifier");
1.212 stevesk 913: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 914: ROQUIET, user_hostfiles, num_user_hostfiles,
915: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 916: debug("found matching key w/out port");
917: break;
918: }
919: }
1.219 djm 920: if (readonly || want_cert)
1.108 markus 921: goto fail;
1.38 markus 922: /* The host is new. */
923: if (options.strict_host_key_checking == 1) {
1.108 markus 924: /*
925: * User has requested strict host key checking. We
926: * will not add the host key automatically. The only
927: * alternative left is to abort.
928: */
929: error("No %s host key is known for %.200s and you "
930: "have requested strict checking.", type, host);
931: goto fail;
1.38 markus 932: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 933: char msg1[1024], msg2[1024];
934:
1.229 djm 935: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 936: snprintf(msg1, sizeof(msg1),
1.168 djm 937: "\nbut keys of different type are already"
938: " known for this host.");
1.145 jakob 939: else
940: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 941: /* The default */
1.259 djm 942: fp = sshkey_fingerprint(host_key,
1.254 djm 943: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 944: ra = sshkey_fingerprint(host_key,
1.254 djm 945: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 946: if (fp == NULL || ra == NULL)
947: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 948: msg2[0] = '\0';
949: if (options.verify_host_key_dns) {
1.153 jakob 950: if (matching_host_key_dns)
1.145 jakob 951: snprintf(msg2, sizeof(msg2),
952: "Matching host key fingerprint"
953: " found in DNS.\n");
954: else
955: snprintf(msg2, sizeof(msg2),
956: "No matching host key fingerprint"
957: " found in DNS.\n");
958: }
1.119 markus 959: snprintf(msg, sizeof(msg),
1.108 markus 960: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 961: "established%s\n"
1.209 grunk 962: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 963: "Are you sure you want to continue connecting "
1.132 markus 964: "(yes/no)? ",
1.209 grunk 965: host, ip, msg1, type, fp,
966: options.visual_host_key ? "\n" : "",
967: options.visual_host_key ? ra : "",
968: msg2);
1.238 djm 969: free(ra);
970: free(fp);
1.119 markus 971: if (!confirm(msg))
1.108 markus 972: goto fail;
1.257 djm 973: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 974: }
1.161 djm 975: /*
976: * If not in strict mode, add the key automatically to the
977: * local known_hosts file.
978: */
1.88 markus 979: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 980: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 981: hostp = hostline;
1.161 djm 982: if (options.hash_known_hosts) {
983: /* Add hash of host and IP separately */
1.234 djm 984: r = add_host_to_hostfile(user_hostfiles[0],
985: host, host_key, options.hash_known_hosts) &&
986: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 987: host_key, options.hash_known_hosts);
988: } else {
989: /* Add unhashed "host,ip" */
1.234 djm 990: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 991: hostline, host_key,
992: options.hash_known_hosts);
993: }
994: } else {
1.234 djm 995: r = add_host_to_hostfile(user_hostfiles[0], host,
996: host_key, options.hash_known_hosts);
1.38 markus 997: hostp = host;
1.161 djm 998: }
1.38 markus 999:
1.161 djm 1000: if (!r)
1.138 itojun 1001: logit("Failed to add the host to the list of known "
1.234 djm 1002: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 1003: else
1.138 itojun 1004: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 1005: "list of known hosts.", hostp, type);
1.38 markus 1006: break;
1.220 djm 1007: case HOST_REVOKED:
1008: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1009: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1010: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1011: error("The %s host key for %s is marked as revoked.", type, host);
1012: error("This could mean that a stolen key is being used to");
1013: error("impersonate this host.");
1014:
1015: /*
1016: * If strict host key checking is in use, the user will have
1017: * to edit the key manually and we can only abort.
1018: */
1019: if (options.strict_host_key_checking) {
1020: error("%s host key for %.200s was revoked and you have "
1021: "requested strict checking.", type, host);
1022: goto fail;
1023: }
1024: goto continue_unsafe;
1025:
1.38 markus 1026: case HOST_CHANGED:
1.219 djm 1027: if (want_cert) {
1028: /*
1029: * This is only a debug() since it is valid to have
1030: * CAs with wildcard DNS matches that don't match
1031: * all hosts that one might visit.
1032: */
1033: debug("Host certificate authority does not "
1.229 djm 1034: "match %s in %s:%lu", CA_MARKER,
1035: host_found->file, host_found->line);
1.219 djm 1036: goto fail;
1037: }
1.197 dtucker 1038: if (readonly == ROQUIET)
1039: goto fail;
1.38 markus 1040: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1041: char *key_msg;
1.38 markus 1042: if (ip_status == HOST_NEW)
1.158 avsm 1043: key_msg = "is unknown";
1.38 markus 1044: else if (ip_status == HOST_OK)
1.158 avsm 1045: key_msg = "is unchanged";
1.38 markus 1046: else
1.158 avsm 1047: key_msg = "has a different value";
1.38 markus 1048: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1049: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1050: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1051: error("The %s host key for %s has changed,", type, host);
1.208 ian 1052: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1053: error("%s. This could either mean that", key_msg);
1.38 markus 1054: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1055: error("and its host key have changed at the same time.");
1.88 markus 1056: if (ip_status != HOST_NEW)
1.229 djm 1057: error("Offending key for IP in %s:%lu",
1058: ip_found->file, ip_found->line);
1.38 markus 1059: }
1060: /* The host key has changed. */
1.150 jakob 1061: warn_changed_key(host_key);
1.38 markus 1062: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1063: user_hostfiles[0]);
1.229 djm 1064: error("Offending %s key in %s:%lu", key_type(host_found->key),
1065: host_found->file, host_found->line);
1.38 markus 1066:
1.40 markus 1067: /*
1068: * If strict host key checking is in use, the user will have
1069: * to edit the key manually and we can only abort.
1070: */
1.108 markus 1071: if (options.strict_host_key_checking) {
1072: error("%s host key for %.200s has changed and you have "
1073: "requested strict checking.", type, host);
1074: goto fail;
1075: }
1.38 markus 1076:
1.220 djm 1077: continue_unsafe:
1.40 markus 1078: /*
1079: * If strict host key checking has not been requested, allow
1.144 djm 1080: * the connection but without MITM-able authentication or
1.194 stevesk 1081: * forwarding.
1.40 markus 1082: */
1.38 markus 1083: if (options.password_authentication) {
1.108 markus 1084: error("Password authentication is disabled to avoid "
1085: "man-in-the-middle attacks.");
1.38 markus 1086: options.password_authentication = 0;
1.210 dtucker 1087: cancelled_forwarding = 1;
1.144 djm 1088: }
1089: if (options.kbd_interactive_authentication) {
1090: error("Keyboard-interactive authentication is disabled"
1091: " to avoid man-in-the-middle attacks.");
1092: options.kbd_interactive_authentication = 0;
1093: options.challenge_response_authentication = 0;
1.210 dtucker 1094: cancelled_forwarding = 1;
1.144 djm 1095: }
1096: if (options.challenge_response_authentication) {
1097: error("Challenge/response authentication is disabled"
1098: " to avoid man-in-the-middle attacks.");
1099: options.challenge_response_authentication = 0;
1.210 dtucker 1100: cancelled_forwarding = 1;
1.38 markus 1101: }
1102: if (options.forward_agent) {
1.108 markus 1103: error("Agent forwarding is disabled to avoid "
1104: "man-in-the-middle attacks.");
1.38 markus 1105: options.forward_agent = 0;
1.210 dtucker 1106: cancelled_forwarding = 1;
1.83 markus 1107: }
1108: if (options.forward_x11) {
1.108 markus 1109: error("X11 forwarding is disabled to avoid "
1110: "man-in-the-middle attacks.");
1.83 markus 1111: options.forward_x11 = 0;
1.210 dtucker 1112: cancelled_forwarding = 1;
1.83 markus 1113: }
1.108 markus 1114: if (options.num_local_forwards > 0 ||
1115: options.num_remote_forwards > 0) {
1116: error("Port forwarding is disabled to avoid "
1117: "man-in-the-middle attacks.");
1118: options.num_local_forwards =
1.118 deraadt 1119: options.num_remote_forwards = 0;
1.210 dtucker 1120: cancelled_forwarding = 1;
1.194 stevesk 1121: }
1122: if (options.tun_open != SSH_TUNMODE_NO) {
1123: error("Tunnel forwarding is disabled to avoid "
1124: "man-in-the-middle attacks.");
1125: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1126: cancelled_forwarding = 1;
1.38 markus 1127: }
1.210 dtucker 1128: if (options.exit_on_forward_failure && cancelled_forwarding)
1129: fatal("Error: forwarding disabled due to host key "
1130: "check failure");
1131:
1.40 markus 1132: /*
1133: * XXX Should permit the user to change to use the new id.
1134: * This could be done by converting the host key to an
1135: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1136: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1137: * accept the authentication.
1138: */
1.38 markus 1139: break;
1.132 markus 1140: case HOST_FOUND:
1141: fatal("internal error");
1142: break;
1.88 markus 1143: }
1144:
1145: if (options.check_host_ip && host_status != HOST_CHANGED &&
1146: ip_status == HOST_CHANGED) {
1.119 markus 1147: snprintf(msg, sizeof(msg),
1148: "Warning: the %s host key for '%.200s' "
1149: "differs from the key for the IP address '%.128s'"
1.229 djm 1150: "\nOffending key for IP in %s:%lu",
1151: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1152: if (host_status == HOST_OK) {
1153: len = strlen(msg);
1154: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1155: "\nMatching host key in %s:%lu",
1156: host_found->file, host_found->line);
1.119 markus 1157: }
1.88 markus 1158: if (options.strict_host_key_checking == 1) {
1.143 djm 1159: logit("%s", msg);
1.108 markus 1160: error("Exiting, you have requested strict checking.");
1161: goto fail;
1.88 markus 1162: } else if (options.strict_host_key_checking == 2) {
1.119 markus 1163: strlcat(msg, "\nAre you sure you want "
1164: "to continue connecting (yes/no)? ", sizeof(msg));
1165: if (!confirm(msg))
1.108 markus 1166: goto fail;
1.119 markus 1167: } else {
1.143 djm 1168: logit("%s", msg);
1.88 markus 1169: }
1.257 djm 1170: }
1171:
1172: if (!hostkey_trusted && options.update_hostkeys) {
1173: debug("%s: hostkey not known or explicitly trusted: "
1174: "disabling UpdateHostkeys", __func__);
1175: options.update_hostkeys = 0;
1.38 markus 1176: }
1.82 provos 1177:
1.238 djm 1178: free(ip);
1179: free(host);
1.229 djm 1180: if (host_hostkeys != NULL)
1181: free_hostkeys(host_hostkeys);
1182: if (ip_hostkeys != NULL)
1183: free_hostkeys(ip_hostkeys);
1.108 markus 1184: return 0;
1185:
1186: fail:
1.220 djm 1187: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1188: /*
1189: * No matching certificate. Downgrade cert to raw key and
1190: * search normally.
1191: */
1192: debug("No matching CA found. Retry with plain key");
1193: raw_key = key_from_private(host_key);
1194: if (key_drop_cert(raw_key) != 0)
1195: fatal("Couldn't drop certificate");
1196: host_key = raw_key;
1197: goto retry;
1198: }
1199: if (raw_key != NULL)
1200: key_free(raw_key);
1.238 djm 1201: free(ip);
1202: free(host);
1.229 djm 1203: if (host_hostkeys != NULL)
1204: free_hostkeys(host_hostkeys);
1205: if (ip_hostkeys != NULL)
1206: free_hostkeys(ip_hostkeys);
1.108 markus 1207: return -1;
1208: }
1209:
1.140 jakob 1210: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1211: int
1212: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1213: {
1.267 ! djm 1214: u_int i;
1.250 djm 1215: int r = -1, flags = 0;
1.267 ! djm 1216: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1217: struct sshkey *plain = NULL;
1.229 djm 1218:
1.252 djm 1219: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1220: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1221: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1222: r = -1;
1223: goto out;
1224: }
1225:
1.267 ! djm 1226: if (sshkey_is_cert(host_key)) {
! 1227: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
! 1228: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
! 1229: error("%s: fingerprint CA key: %s",
! 1230: __func__, ssh_err(r));
! 1231: r = -1;
! 1232: goto out;
! 1233: }
! 1234: sshkey_format_cert_validity(host_key->cert,
! 1235: valid, sizeof(valid));
! 1236: debug("Server host certificate: %s %s, serial %llu "
! 1237: "ID \"%s\" CA %s %s valid %s",
! 1238: sshkey_ssh_name(host_key), fp,
! 1239: host_key->cert->serial, host_key->cert->key_id,
! 1240: sshkey_ssh_name(host_key->cert->signature_key), cafp,
! 1241: valid);
! 1242: for (i = 0; i < host_key->cert->nprincipals; i++) {
! 1243: debug2("Server host certificate hostname: %s",
! 1244: host_key->cert->principals[i]);
! 1245: }
! 1246: } else {
! 1247: debug("Server host key: %s %s", compat20 ?
! 1248: sshkey_ssh_name(host_key) : sshkey_type(host_key), fp);
! 1249: }
1.252 djm 1250:
1251: if (sshkey_equal(previous_host_key, host_key)) {
1252: debug2("%s: server host key %s %s matches cached key",
1253: __func__, sshkey_type(host_key), fp);
1254: r = 0;
1255: goto out;
1256: }
1257:
1258: /* Check in RevokedHostKeys file if specified */
1259: if (options.revoked_host_keys != NULL) {
1260: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1261: switch (r) {
1262: case 0:
1263: break; /* not revoked */
1264: case SSH_ERR_KEY_REVOKED:
1265: error("Host key %s %s revoked by file %s",
1266: sshkey_type(host_key), fp,
1267: options.revoked_host_keys);
1268: r = -1;
1269: goto out;
1270: default:
1271: error("Error checking host key %s %s in "
1272: "revoked keys file %s: %s", sshkey_type(host_key),
1273: fp, options.revoked_host_keys, ssh_err(r));
1274: r = -1;
1275: goto out;
1276: }
1.250 djm 1277: }
1278:
1.247 djm 1279: if (options.verify_host_key_dns) {
1280: /*
1281: * XXX certs are not yet supported for DNS, so downgrade
1282: * them and try the plain key.
1283: */
1.252 djm 1284: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1285: goto out;
1286: if (sshkey_is_cert(plain))
1287: sshkey_drop_cert(plain);
1.247 djm 1288: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1289: if (flags & DNS_VERIFY_FOUND) {
1290: if (options.verify_host_key_dns == 1 &&
1291: flags & DNS_VERIFY_MATCH &&
1292: flags & DNS_VERIFY_SECURE) {
1.250 djm 1293: r = 0;
1.252 djm 1294: goto out;
1.247 djm 1295: }
1296: if (flags & DNS_VERIFY_MATCH) {
1297: matching_host_key_dns = 1;
1298: } else {
1299: warn_changed_key(plain);
1300: error("Update the SSHFP RR in DNS "
1301: "with the new host key to get rid "
1302: "of this message.");
1303: }
1.153 jakob 1304: }
1.140 jakob 1305: }
1306: }
1.250 djm 1307: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1308: options.user_hostfiles, options.num_user_hostfiles,
1309: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1310:
1.252 djm 1311: out:
1312: sshkey_free(plain);
1313: free(fp);
1.267 ! djm 1314: free(cafp);
1.250 djm 1315: if (r == 0 && host_key != NULL) {
1316: key_free(previous_host_key);
1317: previous_host_key = key_from_private(host_key);
1318: }
1319:
1320: return r;
1.51 markus 1321: }
1.70 markus 1322:
1.51 markus 1323: /*
1324: * Starts a dialog with the server, and authenticates the current user on the
1325: * server. This does not need any extra privileges. The basic connection
1326: * to the server must already have been established before this is called.
1327: * If login fails, this function prints an error and never returns.
1328: * This function does not require super-user privileges.
1329: */
1330: void
1.120 markus 1331: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1332: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1333: {
1.241 djm 1334: char *host;
1.70 markus 1335: char *server_user, *local_user;
1336:
1337: local_user = xstrdup(pw->pw_name);
1338: server_user = options.user ? options.user : local_user;
1.51 markus 1339:
1340: /* Convert the user-supplied hostname into all lowercase. */
1341: host = xstrdup(orighost);
1.241 djm 1342: lowercase(host);
1.51 markus 1343:
1344: /* Exchange protocol version identification strings with the server. */
1.202 djm 1345: ssh_exchange_identification(timeout_ms);
1.51 markus 1346:
1347: /* Put the connection into non-blocking mode. */
1348: packet_set_nonblocking();
1349:
1350: /* key exchange */
1351: /* authenticate user */
1.261 dtucker 1352: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.59 markus 1353: if (compat20) {
1.229 djm 1354: ssh_kex2(host, hostaddr, port);
1.120 markus 1355: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 1356: } else {
1.248 markus 1357: #ifdef WITH_SSH1
1.59 markus 1358: ssh_kex(host, hostaddr);
1.120 markus 1359: ssh_userauth1(local_user, server_user, host, sensitive);
1.248 markus 1360: #else
1.260 djm 1361: fatal("ssh1 is not supported");
1.248 markus 1362: #endif
1.59 markus 1363: }
1.238 djm 1364: free(local_user);
1.97 markus 1365: }
1366:
1367: void
1368: ssh_put_password(char *password)
1369: {
1370: int size;
1371: char *padded;
1372:
1.99 deraadt 1373: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1374: packet_put_cstring(password);
1.99 deraadt 1375: return;
1376: }
1.97 markus 1377: size = roundup(strlen(password) + 1, 32);
1.179 djm 1378: padded = xcalloc(1, size);
1.97 markus 1379: strlcpy(padded, password, size);
1380: packet_put_string(padded, size);
1.245 djm 1381: explicit_bzero(padded, size);
1.238 djm 1382: free(padded);
1.132 markus 1383: }
1384:
1385: /* print all known host keys for a given host, but skip keys of given type */
1386: static int
1.229 djm 1387: show_other_keys(struct hostkeys *hostkeys, Key *key)
1.132 markus 1388: {
1.242 djm 1389: int type[] = {
1390: KEY_RSA1,
1391: KEY_RSA,
1392: KEY_DSA,
1393: KEY_ECDSA,
1394: KEY_ED25519,
1395: -1
1396: };
1.229 djm 1397: int i, ret = 0;
1398: char *fp, *ra;
1399: const struct hostkey_entry *found;
1.132 markus 1400:
1401: for (i = 0; type[i] != -1; i++) {
1402: if (type[i] == key->type)
1403: continue;
1.229 djm 1404: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1405: continue;
1.259 djm 1406: fp = sshkey_fingerprint(found->key,
1.254 djm 1407: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1408: ra = sshkey_fingerprint(found->key,
1.254 djm 1409: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1410: if (fp == NULL || ra == NULL)
1411: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1412: logit("WARNING: %s key found for host %s\n"
1413: "in %s:%lu\n"
1414: "%s key fingerprint %s.",
1415: key_type(found->key),
1416: found->host, found->file, found->line,
1417: key_type(found->key), fp);
1418: if (options.visual_host_key)
1419: logit("%s", ra);
1.238 djm 1420: free(ra);
1421: free(fp);
1.229 djm 1422: ret = 1;
1.132 markus 1423: }
1.229 djm 1424: return ret;
1.150 jakob 1425: }
1426:
1427: static void
1428: warn_changed_key(Key *host_key)
1429: {
1430: char *fp;
1431:
1.259 djm 1432: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1433: SSH_FP_DEFAULT);
1.259 djm 1434: if (fp == NULL)
1435: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1436:
1437: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1438: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1439: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1440: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1441: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1442: error("It is also possible that a host key has just been changed.");
1.150 jakob 1443: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.230 markus 1444: key_type(host_key), fp);
1.150 jakob 1445: error("Please contact your system administrator.");
1446:
1.238 djm 1447: free(fp);
1.171 reyk 1448: }
1449:
1450: /*
1451: * Execute a local command
1452: */
1453: int
1454: ssh_local_cmd(const char *args)
1455: {
1456: char *shell;
1457: pid_t pid;
1458: int status;
1.231 djm 1459: void (*osighand)(int);
1.171 reyk 1460:
1461: if (!options.permit_local_command ||
1462: args == NULL || !*args)
1463: return (1);
1464:
1.226 djm 1465: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1466: shell = _PATH_BSHELL;
1467:
1.231 djm 1468: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1469: pid = fork();
1470: if (pid == 0) {
1.232 djm 1471: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1472: debug3("Executing %s -c \"%s\"", shell, args);
1473: execl(shell, shell, "-c", args, (char *)NULL);
1474: error("Couldn't execute %s -c \"%s\": %s",
1475: shell, args, strerror(errno));
1476: _exit(1);
1477: } else if (pid == -1)
1478: fatal("fork failed: %.100s", strerror(errno));
1479: while (waitpid(pid, &status, 0) == -1)
1480: if (errno != EINTR)
1481: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1482: signal(SIGCHLD, osighand);
1.171 reyk 1483:
1484: if (!WIFEXITED(status))
1485: return (1);
1486:
1487: return (WEXITSTATUS(status));
1.266 jcs 1488: }
1489:
1490: void
1491: maybe_add_key_to_agent(char *authfile, Key *private, char *comment,
1492: char *passphrase)
1493: {
1494: int auth_sock = -1, r;
1495:
1496: if (options.add_keys_to_agent == 0)
1497: return;
1498:
1499: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1500: debug3("no authentication agent, not adding key");
1501: return;
1502: }
1503:
1504: if (options.add_keys_to_agent == 2 &&
1505: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1506: debug3("user denied adding this key");
1507: return;
1508: }
1509:
1510: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1511: (options.add_keys_to_agent == 3))) == 0)
1512: debug("identity added to agent: %s", authfile);
1513: else
1514: debug("could not add identity to agent: %s (%d)", authfile, r);
1.1 deraadt 1515: }
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