Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.260
1.260 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.259 2015/01/28 22:36:00 djm Exp $ */
1.1 deraadt 2: /*
1.39 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
1.78 deraadt 8: *
9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 14: */
1.1 deraadt 15:
1.256 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"
1.140 jakob 58:
1.70 markus 59: char *client_version_string = NULL;
60: char *server_version_string = NULL;
1.250 djm 61: Key *previous_host_key = NULL;
1.59 markus 62:
1.169 stevesk 63: static int matching_host_key_dns = 0;
1.145 jakob 64:
1.227 djm 65: static pid_t proxy_command_pid = 0;
66:
1.124 markus 67: /* import */
1.43 markus 68: extern Options options;
1.50 markus 69: extern char *__progname;
1.124 markus 70: extern uid_t original_real_uid;
71: extern uid_t original_effective_uid;
1.91 markus 72:
1.229 djm 73: static int show_other_keys(struct hostkeys *, Key *);
1.150 jakob 74: static void warn_changed_key(Key *);
1.132 markus 75:
1.239 djm 76: /* Expand a proxy command */
77: static char *
78: expand_proxy_command(const char *proxy_command, const char *user,
79: const char *host, int port)
80: {
81: char *tmp, *ret, strport[NI_MAXSERV];
82:
1.241 djm 83: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 84: xasprintf(&tmp, "exec %s", proxy_command);
85: ret = percent_expand(tmp, "h", host, "p", strport,
86: "r", options.user, (char *)NULL);
87: free(tmp);
88: return ret;
89: }
90:
91: /*
92: * Connect to the given ssh server using a proxy command that passes a
93: * a connected fd back to us.
94: */
95: static int
96: ssh_proxy_fdpass_connect(const char *host, u_short port,
97: const char *proxy_command)
98: {
99: char *command_string;
100: int sp[2], sock;
101: pid_t pid;
102: char *shell;
103:
104: if ((shell = getenv("SHELL")) == NULL)
105: shell = _PATH_BSHELL;
106:
107: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
108: fatal("Could not create socketpair to communicate with "
109: "proxy dialer: %.100s", strerror(errno));
110:
111: command_string = expand_proxy_command(proxy_command, options.user,
112: host, port);
113: debug("Executing proxy dialer command: %.500s", command_string);
114:
115: /* Fork and execute the proxy command. */
116: if ((pid = fork()) == 0) {
117: char *argv[10];
118:
119: /* Child. Permanently give up superuser privileges. */
120: permanently_drop_suid(original_real_uid);
121:
122: close(sp[1]);
123: /* Redirect stdin and stdout. */
124: if (sp[0] != 0) {
125: if (dup2(sp[0], 0) < 0)
126: perror("dup2 stdin");
127: }
128: if (sp[0] != 1) {
129: if (dup2(sp[0], 1) < 0)
130: perror("dup2 stdout");
131: }
132: if (sp[0] >= 2)
133: close(sp[0]);
134:
135: /*
136: * Stderr is left as it is so that error messages get
137: * printed on the user's terminal.
138: */
139: argv[0] = shell;
140: argv[1] = "-c";
141: argv[2] = command_string;
142: argv[3] = NULL;
143:
144: /*
145: * Execute the proxy command.
146: * Note that we gave up any extra privileges above.
147: */
148: execv(argv[0], argv);
149: perror(argv[0]);
150: exit(1);
151: }
152: /* Parent. */
153: if (pid < 0)
154: fatal("fork failed: %.100s", strerror(errno));
155: close(sp[0]);
156: free(command_string);
157:
158: if ((sock = mm_receive_fd(sp[1])) == -1)
159: fatal("proxy dialer did not pass back a connection");
160:
161: while (waitpid(pid, NULL, 0) == -1)
162: if (errno != EINTR)
163: fatal("Couldn't wait for child: %s", strerror(errno));
164:
165: /* Set the connection file descriptors. */
166: packet_set_connection(sock, sock);
167:
168: return 0;
169: }
170:
1.39 deraadt 171: /*
172: * Connect to the given ssh server using a proxy command.
173: */
1.109 itojun 174: static int
1.124 markus 175: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 176: {
1.239 djm 177: char *command_string;
1.38 markus 178: int pin[2], pout[2];
1.69 deraadt 179: pid_t pid;
1.239 djm 180: char *shell;
1.237 markus 181:
1.226 djm 182: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 183: shell = _PATH_BSHELL;
1.38 markus 184:
185: /* Create pipes for communicating with the proxy. */
186: if (pipe(pin) < 0 || pipe(pout) < 0)
187: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 188: strerror(errno));
1.38 markus 189:
1.239 djm 190: command_string = expand_proxy_command(proxy_command, options.user,
191: host, port);
1.38 markus 192: debug("Executing proxy command: %.500s", command_string);
193:
194: /* Fork and execute the proxy command. */
195: if ((pid = fork()) == 0) {
196: char *argv[10];
197:
198: /* Child. Permanently give up superuser privileges. */
1.184 markus 199: permanently_drop_suid(original_real_uid);
1.38 markus 200:
201: /* Redirect stdin and stdout. */
202: close(pin[1]);
203: if (pin[0] != 0) {
204: if (dup2(pin[0], 0) < 0)
205: perror("dup2 stdin");
206: close(pin[0]);
207: }
208: close(pout[0]);
209: if (dup2(pout[1], 1) < 0)
210: perror("dup2 stdout");
211: /* Cannot be 1 because pin allocated two descriptors. */
212: close(pout[1]);
213:
214: /* Stderr is left as it is so that error messages get
215: printed on the user's terminal. */
1.201 djm 216: argv[0] = shell;
1.38 markus 217: argv[1] = "-c";
218: argv[2] = command_string;
219: argv[3] = NULL;
220:
221: /* Execute the proxy command. Note that we gave up any
222: extra privileges above. */
1.232 djm 223: signal(SIGPIPE, SIG_DFL);
1.89 markus 224: execv(argv[0], argv);
225: perror(argv[0]);
1.38 markus 226: exit(1);
227: }
228: /* Parent. */
229: if (pid < 0)
230: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 231: else
232: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 233:
234: /* Close child side of the descriptors. */
235: close(pin[0]);
236: close(pout[1]);
237:
238: /* Free the command name. */
1.238 djm 239: free(command_string);
1.38 markus 240:
241: /* Set the connection file descriptors. */
242: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 243:
1.110 markus 244: /* Indicate OK return */
245: return 0;
1.227 djm 246: }
247:
248: void
249: ssh_kill_proxy_command(void)
250: {
251: /*
252: * Send SIGHUP to proxy command if used. We don't wait() in
253: * case it hangs and instead rely on init to reap the child
254: */
255: if (proxy_command_pid > 1)
1.228 djm 256: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 257: }
258:
1.39 deraadt 259: /*
260: * Creates a (possibly privileged) socket for use as the ssh connection.
261: */
1.109 itojun 262: static int
1.139 markus 263: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 264: {
1.240 djm 265: int sock, r, gaierr;
1.246 djm 266: struct addrinfo hints, *res = NULL;
1.1 deraadt 267:
1.217 dtucker 268: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 269: if (sock < 0) {
1.240 djm 270: error("socket: %s", strerror(errno));
1.216 dtucker 271: return -1;
272: }
273: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 274:
275: /* Bind the socket to an alternative local IP address */
1.240 djm 276: if (options.bind_address == NULL && !privileged)
1.105 markus 277: return sock;
278:
1.246 djm 279: if (options.bind_address) {
280: memset(&hints, 0, sizeof(hints));
281: hints.ai_family = ai->ai_family;
282: hints.ai_socktype = ai->ai_socktype;
283: hints.ai_protocol = ai->ai_protocol;
284: hints.ai_flags = AI_PASSIVE;
285: gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
286: if (gaierr) {
287: error("getaddrinfo: %s: %s", options.bind_address,
288: ssh_gai_strerror(gaierr));
289: close(sock);
290: return -1;
291: }
1.105 markus 292: }
1.240 djm 293: /*
294: * If we are running as root and want to connect to a privileged
295: * port, bind our own socket to a privileged port.
296: */
297: if (privileged) {
298: PRIV_START;
1.246 djm 299: r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
1.240 djm 300: PRIV_END;
301: if (r < 0) {
302: error("bindresvport_sa: af=%d %s", ai->ai_family,
303: strerror(errno));
304: goto fail;
305: }
306: } else {
307: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
308: error("bind: %s: %s", options.bind_address,
309: strerror(errno));
310: fail:
311: close(sock);
312: freeaddrinfo(res);
313: return -1;
314: }
1.38 markus 315: }
1.246 djm 316: if (res != NULL)
317: freeaddrinfo(res);
1.38 markus 318: return sock;
1.1 deraadt 319: }
320:
1.141 djm 321: static int
322: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 323: socklen_t addrlen, int *timeoutp)
1.141 djm 324: {
325: fd_set *fdset;
1.202 djm 326: struct timeval tv, t_start;
1.141 djm 327: socklen_t optlen;
1.179 djm 328: int optval, rc, result = -1;
1.141 djm 329:
1.202 djm 330: gettimeofday(&t_start, NULL);
331:
332: if (*timeoutp <= 0) {
333: result = connect(sockfd, serv_addr, addrlen);
334: goto done;
335: }
1.141 djm 336:
1.156 djm 337: set_nonblock(sockfd);
1.141 djm 338: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 339: if (rc == 0) {
340: unset_nonblock(sockfd);
1.202 djm 341: result = 0;
342: goto done;
343: }
344: if (errno != EINPROGRESS) {
345: result = -1;
346: goto done;
1.156 djm 347: }
1.141 djm 348:
1.179 djm 349: fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
350: sizeof(fd_mask));
1.141 djm 351: FD_SET(sockfd, fdset);
1.202 djm 352: ms_to_timeval(&tv, *timeoutp);
1.141 djm 353:
1.162 deraadt 354: for (;;) {
1.141 djm 355: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
356: if (rc != -1 || errno != EINTR)
357: break;
358: }
359:
1.162 deraadt 360: switch (rc) {
1.141 djm 361: case 0:
362: /* Timed out */
363: errno = ETIMEDOUT;
1.142 djm 364: break;
1.141 djm 365: case -1:
366: /* Select error */
1.154 djm 367: debug("select: %s", strerror(errno));
1.142 djm 368: break;
1.141 djm 369: case 1:
370: /* Completed or failed */
371: optval = 0;
372: optlen = sizeof(optval);
1.154 djm 373: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 374: &optlen) == -1) {
1.154 djm 375: debug("getsockopt: %s", strerror(errno));
1.142 djm 376: break;
1.148 markus 377: }
1.141 djm 378: if (optval != 0) {
379: errno = optval;
1.142 djm 380: break;
1.141 djm 381: }
1.142 djm 382: result = 0;
1.156 djm 383: unset_nonblock(sockfd);
1.141 djm 384: break;
385: default:
386: /* Should not occur */
387: fatal("Bogus return (%d) from select()", rc);
388: }
389:
1.238 djm 390: free(fdset);
1.202 djm 391:
392: done:
393: if (result == 0 && *timeoutp > 0) {
394: ms_subtract_diff(&t_start, timeoutp);
395: if (*timeoutp <= 0) {
396: errno = ETIMEDOUT;
397: result = -1;
398: }
399: }
400:
1.142 djm 401: return (result);
1.141 djm 402: }
403:
1.39 deraadt 404: /*
1.49 markus 405: * Opens a TCP/IP connection to the remote server on the given host.
406: * The address of the remote host will be returned in hostaddr.
1.124 markus 407: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 408: * a privileged port will be allocated to make the connection.
1.124 markus 409: * This requires super-user privileges if needpriv is true.
1.39 deraadt 410: * Connection_attempts specifies the maximum number of tries (one per
411: * second). If proxy_command is non-NULL, it specifies the command (with %h
412: * and %p substituted for host and port, respectively) to use to contact
413: * the daemon.
414: */
1.241 djm 415: static int
416: ssh_connect_direct(const char *host, struct addrinfo *aitop,
417: struct sockaddr_storage *hostaddr, u_short port, int family,
418: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
1.1 deraadt 419: {
1.90 markus 420: int on = 1;
1.49 markus 421: int sock = -1, attempt;
1.90 markus 422: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 423: struct addrinfo *ai;
1.38 markus 424:
1.136 markus 425: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 426:
1.181 markus 427: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 428: if (attempt > 0) {
429: /* Sleep a moment before retrying. */
430: sleep(1);
1.38 markus 431: debug("Trying again...");
1.200 markus 432: }
1.181 markus 433: /*
434: * Loop through addresses for this host, and try each one in
435: * sequence until the connection succeeds.
436: */
1.49 markus 437: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 438: if (ai->ai_family != AF_INET &&
439: ai->ai_family != AF_INET6)
1.49 markus 440: continue;
441: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
442: ntop, sizeof(ntop), strport, sizeof(strport),
443: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
444: error("ssh_connect: getnameinfo failed");
445: continue;
446: }
447: debug("Connecting to %.200s [%.100s] port %s.",
448: host, ntop, strport);
449:
450: /* Create a socket for connecting. */
1.139 markus 451: sock = ssh_create_socket(needpriv, ai);
1.49 markus 452: if (sock < 0)
1.110 markus 453: /* Any error is already output */
1.49 markus 454: continue;
455:
1.141 djm 456: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 457: timeout_ms) >= 0) {
1.49 markus 458: /* Successful connection. */
1.102 markus 459: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 460: break;
1.49 markus 461: } else {
1.131 itojun 462: debug("connect to address %s port %s: %s",
463: ntop, strport, strerror(errno));
1.38 markus 464: close(sock);
1.181 markus 465: sock = -1;
1.38 markus 466: }
467: }
1.181 markus 468: if (sock != -1)
1.49 markus 469: break; /* Successful connection. */
1.38 markus 470: }
1.49 markus 471:
1.38 markus 472: /* Return failure if we didn't get a successful connection. */
1.181 markus 473: if (sock == -1) {
1.159 markus 474: error("ssh: connect to host %s port %s: %s",
1.130 itojun 475: host, strport, strerror(errno));
1.159 markus 476: return (-1);
1.130 itojun 477: }
1.38 markus 478:
479: debug("Connection established.");
1.90 markus 480:
1.155 markus 481: /* Set SO_KEEPALIVE if requested. */
1.202 djm 482: if (want_keepalive &&
1.90 markus 483: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
484: sizeof(on)) < 0)
485: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 486:
487: /* Set the connection. */
488: packet_set_connection(sock, sock);
1.1 deraadt 489:
1.110 markus 490: return 0;
1.59 markus 491: }
492:
1.241 djm 493: int
494: ssh_connect(const char *host, struct addrinfo *addrs,
495: struct sockaddr_storage *hostaddr, u_short port, int family,
496: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
497: {
498: if (options.proxy_command == NULL) {
499: return ssh_connect_direct(host, addrs, hostaddr, port, family,
500: connection_attempts, timeout_ms, want_keepalive, needpriv);
501: } else if (strcmp(options.proxy_command, "-") == 0) {
502: packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
503: return 0; /* Always succeeds */
504: } else if (options.proxy_use_fdpass) {
505: return ssh_proxy_fdpass_connect(host, port,
506: options.proxy_command);
507: }
508: return ssh_proxy_connect(host, port, options.proxy_command);
509: }
510:
1.235 djm 511: static void
512: send_client_banner(int connection_out, int minor1)
513: {
514: /* Send our own protocol version identification. */
515: if (compat20) {
516: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
517: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
518: } else {
519: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n",
520: PROTOCOL_MAJOR_1, minor1, SSH_VERSION);
521: }
522: if (roaming_atomicio(vwrite, connection_out, client_version_string,
523: strlen(client_version_string)) != strlen(client_version_string))
524: fatal("write: %.100s", strerror(errno));
525: chop(client_version_string);
526: debug("Local version string %.100s", client_version_string);
527: }
528:
1.43 markus 529: /*
1.39 deraadt 530: * Waits for the server identification string, and sends our own
531: * identification string.
532: */
1.213 andreas 533: void
1.202 djm 534: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 535: {
1.38 markus 536: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 537: int remote_major, remote_minor, mismatch;
1.38 markus 538: int connection_in = packet_get_connection_in();
539: int connection_out = packet_get_connection_out();
1.235 djm 540: int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
1.185 djm 541: u_int i, n;
1.202 djm 542: size_t len;
543: int fdsetsz, remaining, rc;
544: struct timeval t_start, t_remaining;
545: fd_set *fdset;
546:
547: fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
548: fdset = xcalloc(1, fdsetsz);
1.38 markus 549:
1.235 djm 550: /*
551: * If we are SSH2-only then we can send the banner immediately and
552: * save a round-trip.
553: */
554: if (options.protocol == SSH_PROTO_2) {
555: enable_compat20();
556: send_client_banner(connection_out, 0);
557: client_banner_sent = 1;
558: }
559:
1.163 avsm 560: /* Read other side's version identification. */
1.202 djm 561: remaining = timeout_ms;
1.185 djm 562: for (n = 0;;) {
1.75 markus 563: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 564: if (timeout_ms > 0) {
565: gettimeofday(&t_start, NULL);
566: ms_to_timeval(&t_remaining, remaining);
567: FD_SET(connection_in, fdset);
568: rc = select(connection_in + 1, fdset, NULL,
569: fdset, &t_remaining);
570: ms_subtract_diff(&t_start, &remaining);
571: if (rc == 0 || remaining <= 0)
572: fatal("Connection timed out during "
573: "banner exchange");
574: if (rc == -1) {
575: if (errno == EINTR)
576: continue;
577: fatal("ssh_exchange_identification: "
578: "select: %s", strerror(errno));
579: }
580: }
581:
1.214 andreas 582: len = roaming_atomicio(read, connection_in, &buf[i], 1);
1.163 avsm 583:
1.167 djm 584: if (len != 1 && errno == EPIPE)
1.202 djm 585: fatal("ssh_exchange_identification: "
586: "Connection closed by remote host");
1.163 avsm 587: else if (len != 1)
1.202 djm 588: fatal("ssh_exchange_identification: "
589: "read: %.100s", strerror(errno));
1.75 markus 590: if (buf[i] == '\r') {
591: buf[i] = '\n';
592: buf[i + 1] = 0;
593: continue; /**XXX wait for \n */
594: }
595: if (buf[i] == '\n') {
596: buf[i + 1] = 0;
597: break;
598: }
1.185 djm 599: if (++n > 65536)
1.202 djm 600: fatal("ssh_exchange_identification: "
601: "No banner received");
1.38 markus 602: }
1.75 markus 603: buf[sizeof(buf) - 1] = 0;
1.76 markus 604: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 605: break;
1.75 markus 606: debug("ssh_exchange_identification: %s", buf);
1.38 markus 607: }
1.59 markus 608: server_version_string = xstrdup(buf);
1.238 djm 609: free(fdset);
1.38 markus 610:
1.40 markus 611: /*
612: * Check that the versions match. In future this might accept
613: * several versions and set appropriate flags to handle them.
614: */
1.59 markus 615: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
616: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 617: fatal("Bad remote protocol version identification: '%.100s'", buf);
618: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 619: remote_major, remote_minor, remote_version);
1.38 markus 620:
1.255 markus 621: active_state->compat = compat_datafellows(remote_version);
1.64 markus 622: mismatch = 0;
1.59 markus 623:
1.116 deraadt 624: switch (remote_major) {
1.64 markus 625: case 1:
626: if (remote_minor == 99 &&
627: (options.protocol & SSH_PROTO_2) &&
628: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
629: enable_compat20();
630: break;
631: }
632: if (!(options.protocol & SSH_PROTO_1)) {
633: mismatch = 1;
634: break;
635: }
636: if (remote_minor < 3) {
637: fatal("Remote machine has too old SSH software version.");
1.81 markus 638: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 639: /* We speak 1.3, too. */
640: enable_compat13();
1.81 markus 641: minor1 = 3;
1.64 markus 642: if (options.forward_agent) {
1.138 itojun 643: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 644: options.forward_agent = 0;
645: }
646: }
647: break;
648: case 2:
649: if (options.protocol & SSH_PROTO_2) {
650: enable_compat20();
651: break;
1.38 markus 652: }
1.64 markus 653: /* FALLTHROUGH */
1.68 markus 654: default:
1.64 markus 655: mismatch = 1;
656: break;
1.38 markus 657: }
1.64 markus 658: if (mismatch)
1.38 markus 659: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 660: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
661: remote_major);
1.244 djm 662: if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
663: fatal("Server version \"%.100s\" uses unsafe key agreement; "
664: "refusing connection", remote_version);
1.243 djm 665: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
666: logit("Server version \"%.100s\" uses unsafe RSA signature "
667: "scheme; disabling use of RSA keys", remote_version);
1.235 djm 668: if (!client_banner_sent)
669: send_client_banner(connection_out, minor1);
1.59 markus 670: chop(server_version_string);
1.1 deraadt 671: }
672:
1.96 markus 673: /* defaults to 'no' */
1.109 itojun 674: static int
1.112 markus 675: confirm(const char *prompt)
1.1 deraadt 676: {
1.119 markus 677: const char *msg, *again = "Please type 'yes' or 'no': ";
678: char *p;
679: int ret = -1;
1.96 markus 680:
681: if (options.batch_mode)
682: return 0;
1.119 markus 683: for (msg = prompt;;msg = again) {
684: p = read_passphrase(msg, RP_ECHO);
685: if (p == NULL ||
686: (p[0] == '\0') || (p[0] == '\n') ||
687: strncasecmp(p, "no", 2) == 0)
688: ret = 0;
1.127 markus 689: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 690: ret = 1;
1.238 djm 691: free(p);
1.119 markus 692: if (ret != -1)
693: return ret;
1.1 deraadt 694: }
695: }
696:
1.219 djm 697: static int
698: check_host_cert(const char *host, const Key *host_key)
699: {
700: const char *reason;
701:
702: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
703: error("%s", reason);
704: return 0;
705: }
1.249 djm 706: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 707: error("Certificate for %s contains unsupported "
708: "critical options(s)", host);
1.219 djm 709: return 0;
710: }
711: return 1;
712: }
713:
1.229 djm 714: static int
715: sockaddr_is_local(struct sockaddr *hostaddr)
716: {
717: switch (hostaddr->sa_family) {
718: case AF_INET:
719: return (ntohl(((struct sockaddr_in *)hostaddr)->
720: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
721: case AF_INET6:
722: return IN6_IS_ADDR_LOOPBACK(
723: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
724: default:
725: return 0;
726: }
727: }
728:
729: /*
730: * Prepare the hostname and ip address strings that are used to lookup
731: * host keys in known_hosts files. These may have a port number appended.
732: */
733: void
734: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
735: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
736: {
737: char ntop[NI_MAXHOST];
738:
739: /*
740: * We don't have the remote ip-address for connections
741: * using a proxy command
742: */
743: if (hostfile_ipaddr != NULL) {
744: if (options.proxy_command == NULL) {
745: if (getnameinfo(hostaddr, hostaddr->sa_len,
746: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 747: fatal("%s: getnameinfo failed", __func__);
1.229 djm 748: *hostfile_ipaddr = put_host_port(ntop, port);
749: } else {
750: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
751: "command>");
752: }
753: }
754:
755: /*
756: * Allow the user to record the key under a different name or
757: * differentiate a non-standard port. This is useful for ssh
758: * tunneling over forwarded connections or if you run multiple
759: * sshd's on different ports on the same machine.
760: */
761: if (hostfile_hostname != NULL) {
762: if (options.host_key_alias != NULL) {
763: *hostfile_hostname = xstrdup(options.host_key_alias);
764: debug("using hostkeyalias: %s", *hostfile_hostname);
765: } else {
766: *hostfile_hostname = put_host_port(hostname, port);
767: }
768: }
769: }
770:
1.39 deraadt 771: /*
1.108 markus 772: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 773: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 774: */
1.197 dtucker 775: #define RDRW 0
776: #define RDONLY 1
777: #define ROQUIET 2
1.109 itojun 778: static int
1.197 dtucker 779: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.234 djm 780: Key *host_key, int readonly,
781: char **user_hostfiles, u_int num_user_hostfiles,
782: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 783: {
1.234 djm 784: HostStatus host_status;
785: HostStatus ip_status;
1.229 djm 786: Key *raw_key = NULL;
1.189 dtucker 787: char *ip = NULL, *host = NULL;
1.204 grunk 788: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 789: char msg[1024];
1.234 djm 790: const char *type;
791: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 792: int len, cancelled_forwarding = 0;
1.234 djm 793: int local = sockaddr_is_local(hostaddr);
794: int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
1.257 djm 795: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 796: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 797: u_int i;
1.49 markus 798:
799: /*
800: * Force accepting of the host key for loopback/localhost. The
801: * problem is that if the home directory is NFS-mounted to multiple
802: * machines, localhost will refer to a different machine in each of
803: * them, and the user will get bogus HOST_CHANGED warnings. This
804: * essentially disables host authentication for localhost; however,
805: * this is probably not a real problem.
806: */
1.111 markus 807: if (options.no_host_authentication_for_localhost == 1 && local &&
808: options.host_key_alias == NULL) {
1.88 markus 809: debug("Forcing accepting of host key for "
810: "loopback/localhost.");
1.108 markus 811: return 0;
1.49 markus 812: }
1.42 markus 813:
814: /*
1.229 djm 815: * Prepare the hostname and address strings used for hostkey lookup.
816: * In some cases, these will have a port number appended.
1.42 markus 817: */
1.229 djm 818: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 819:
820: /*
1.88 markus 821: * Turn off check_host_ip if the connection is to localhost, via proxy
822: * command or if we don't have a hostname to compare with
823: */
1.189 dtucker 824: if (options.check_host_ip && (local ||
825: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 826: options.check_host_ip = 0;
1.86 markus 827:
1.229 djm 828: host_hostkeys = init_hostkeys();
1.234 djm 829: for (i = 0; i < num_user_hostfiles; i++)
830: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
831: for (i = 0; i < num_system_hostfiles; i++)
832: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 833:
834: ip_hostkeys = NULL;
835: if (!want_cert && options.check_host_ip) {
836: ip_hostkeys = init_hostkeys();
1.234 djm 837: for (i = 0; i < num_user_hostfiles; i++)
838: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
839: for (i = 0; i < num_system_hostfiles; i++)
840: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 841: }
1.38 markus 842:
1.219 djm 843: retry:
1.229 djm 844: /* Reload these as they may have changed on cert->key downgrade */
1.219 djm 845: want_cert = key_is_cert(host_key);
846: type = key_type(host_key);
847:
1.46 markus 848: /*
1.170 djm 849: * Check if the host key is present in the user's list of known
1.40 markus 850: * hosts or in the systemwide list.
851: */
1.229 djm 852: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
853: &host_found);
854:
1.40 markus 855: /*
856: * Also perform check for the ip address, skip the check if we are
1.219 djm 857: * localhost, looking for a certificate, or the hostname was an ip
858: * address to begin with.
1.40 markus 859: */
1.229 djm 860: if (!want_cert && ip_hostkeys != NULL) {
861: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
862: &ip_found);
1.38 markus 863: if (host_status == HOST_CHANGED &&
1.229 djm 864: (ip_status != HOST_CHANGED ||
865: (ip_found != NULL &&
866: !key_equal(ip_found->key, host_found->key))))
1.38 markus 867: host_ip_differ = 1;
868: } else
869: ip_status = host_status;
870:
871: switch (host_status) {
872: case HOST_OK:
873: /* The host is known and the key matches. */
1.219 djm 874: debug("Host '%.200s' is known and matches the %s host %s.",
875: host, type, want_cert ? "certificate" : "key");
1.229 djm 876: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
877: host_found->file, host_found->line);
1.219 djm 878: if (want_cert && !check_host_cert(hostname, host_key))
879: goto fail;
1.88 markus 880: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 881: if (readonly || want_cert)
1.138 itojun 882: logit("%s host key for IP address "
1.108 markus 883: "'%.128s' not in list of known hosts.",
884: type, ip);
1.234 djm 885: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 886: host_key, options.hash_known_hosts))
1.138 itojun 887: logit("Failed to add the %s host key for IP "
1.108 markus 888: "address '%.128s' to the list of known "
1.234 djm 889: "hosts (%.30s).", type, ip,
890: user_hostfiles[0]);
1.88 markus 891: else
1.138 itojun 892: logit("Warning: Permanently added the %s host "
1.108 markus 893: "key for IP address '%.128s' to the list "
894: "of known hosts.", type, ip);
1.209 grunk 895: } else if (options.visual_host_key) {
1.259 djm 896: fp = sshkey_fingerprint(host_key,
1.254 djm 897: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 898: ra = sshkey_fingerprint(host_key,
1.254 djm 899: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 900: if (fp == NULL || ra == NULL)
901: fatal("%s: sshkey_fingerprint fail", __func__);
1.204 grunk 902: logit("Host key fingerprint is %s\n%s\n", fp, ra);
1.238 djm 903: free(ra);
904: free(fp);
1.38 markus 905: }
1.257 djm 906: hostkey_trusted = 1;
1.38 markus 907: break;
908: case HOST_NEW:
1.197 dtucker 909: if (options.host_key_alias == NULL && port != 0 &&
910: port != SSH_DEFAULT_PORT) {
911: debug("checking without port identifier");
1.212 stevesk 912: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 913: ROQUIET, user_hostfiles, num_user_hostfiles,
914: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 915: debug("found matching key w/out port");
916: break;
917: }
918: }
1.219 djm 919: if (readonly || want_cert)
1.108 markus 920: goto fail;
1.38 markus 921: /* The host is new. */
922: if (options.strict_host_key_checking == 1) {
1.108 markus 923: /*
924: * User has requested strict host key checking. We
925: * will not add the host key automatically. The only
926: * alternative left is to abort.
927: */
928: error("No %s host key is known for %.200s and you "
929: "have requested strict checking.", type, host);
930: goto fail;
1.38 markus 931: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 932: char msg1[1024], msg2[1024];
933:
1.229 djm 934: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 935: snprintf(msg1, sizeof(msg1),
1.168 djm 936: "\nbut keys of different type are already"
937: " known for this host.");
1.145 jakob 938: else
939: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 940: /* The default */
1.259 djm 941: fp = sshkey_fingerprint(host_key,
1.254 djm 942: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 943: ra = sshkey_fingerprint(host_key,
1.254 djm 944: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 945: if (fp == NULL || ra == NULL)
946: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 947: msg2[0] = '\0';
948: if (options.verify_host_key_dns) {
1.153 jakob 949: if (matching_host_key_dns)
1.145 jakob 950: snprintf(msg2, sizeof(msg2),
951: "Matching host key fingerprint"
952: " found in DNS.\n");
953: else
954: snprintf(msg2, sizeof(msg2),
955: "No matching host key fingerprint"
956: " found in DNS.\n");
957: }
1.119 markus 958: snprintf(msg, sizeof(msg),
1.108 markus 959: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 960: "established%s\n"
1.209 grunk 961: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 962: "Are you sure you want to continue connecting "
1.132 markus 963: "(yes/no)? ",
1.209 grunk 964: host, ip, msg1, type, fp,
965: options.visual_host_key ? "\n" : "",
966: options.visual_host_key ? ra : "",
967: msg2);
1.238 djm 968: free(ra);
969: free(fp);
1.119 markus 970: if (!confirm(msg))
1.108 markus 971: goto fail;
1.257 djm 972: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 973: }
1.161 djm 974: /*
975: * If not in strict mode, add the key automatically to the
976: * local known_hosts file.
977: */
1.88 markus 978: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 979: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 980: hostp = hostline;
1.161 djm 981: if (options.hash_known_hosts) {
982: /* Add hash of host and IP separately */
1.234 djm 983: r = add_host_to_hostfile(user_hostfiles[0],
984: host, host_key, options.hash_known_hosts) &&
985: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 986: host_key, options.hash_known_hosts);
987: } else {
988: /* Add unhashed "host,ip" */
1.234 djm 989: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 990: hostline, host_key,
991: options.hash_known_hosts);
992: }
993: } else {
1.234 djm 994: r = add_host_to_hostfile(user_hostfiles[0], host,
995: host_key, options.hash_known_hosts);
1.38 markus 996: hostp = host;
1.161 djm 997: }
1.38 markus 998:
1.161 djm 999: if (!r)
1.138 itojun 1000: logit("Failed to add the host to the list of known "
1.234 djm 1001: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 1002: else
1.138 itojun 1003: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 1004: "list of known hosts.", hostp, type);
1.38 markus 1005: break;
1.220 djm 1006: case HOST_REVOKED:
1007: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1008: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1009: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1010: error("The %s host key for %s is marked as revoked.", type, host);
1011: error("This could mean that a stolen key is being used to");
1012: error("impersonate this host.");
1013:
1014: /*
1015: * If strict host key checking is in use, the user will have
1016: * to edit the key manually and we can only abort.
1017: */
1018: if (options.strict_host_key_checking) {
1019: error("%s host key for %.200s was revoked and you have "
1020: "requested strict checking.", type, host);
1021: goto fail;
1022: }
1023: goto continue_unsafe;
1024:
1.38 markus 1025: case HOST_CHANGED:
1.219 djm 1026: if (want_cert) {
1027: /*
1028: * This is only a debug() since it is valid to have
1029: * CAs with wildcard DNS matches that don't match
1030: * all hosts that one might visit.
1031: */
1032: debug("Host certificate authority does not "
1.229 djm 1033: "match %s in %s:%lu", CA_MARKER,
1034: host_found->file, host_found->line);
1.219 djm 1035: goto fail;
1036: }
1.197 dtucker 1037: if (readonly == ROQUIET)
1038: goto fail;
1.38 markus 1039: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1040: char *key_msg;
1.38 markus 1041: if (ip_status == HOST_NEW)
1.158 avsm 1042: key_msg = "is unknown";
1.38 markus 1043: else if (ip_status == HOST_OK)
1.158 avsm 1044: key_msg = "is unchanged";
1.38 markus 1045: else
1.158 avsm 1046: key_msg = "has a different value";
1.38 markus 1047: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1048: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1049: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1050: error("The %s host key for %s has changed,", type, host);
1.208 ian 1051: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1052: error("%s. This could either mean that", key_msg);
1.38 markus 1053: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1054: error("and its host key have changed at the same time.");
1.88 markus 1055: if (ip_status != HOST_NEW)
1.229 djm 1056: error("Offending key for IP in %s:%lu",
1057: ip_found->file, ip_found->line);
1.38 markus 1058: }
1059: /* The host key has changed. */
1.150 jakob 1060: warn_changed_key(host_key);
1.38 markus 1061: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1062: user_hostfiles[0]);
1.229 djm 1063: error("Offending %s key in %s:%lu", key_type(host_found->key),
1064: host_found->file, host_found->line);
1.38 markus 1065:
1.40 markus 1066: /*
1067: * If strict host key checking is in use, the user will have
1068: * to edit the key manually and we can only abort.
1069: */
1.108 markus 1070: if (options.strict_host_key_checking) {
1071: error("%s host key for %.200s has changed and you have "
1072: "requested strict checking.", type, host);
1073: goto fail;
1074: }
1.38 markus 1075:
1.220 djm 1076: continue_unsafe:
1.40 markus 1077: /*
1078: * If strict host key checking has not been requested, allow
1.144 djm 1079: * the connection but without MITM-able authentication or
1.194 stevesk 1080: * forwarding.
1.40 markus 1081: */
1.38 markus 1082: if (options.password_authentication) {
1.108 markus 1083: error("Password authentication is disabled to avoid "
1084: "man-in-the-middle attacks.");
1.38 markus 1085: options.password_authentication = 0;
1.210 dtucker 1086: cancelled_forwarding = 1;
1.144 djm 1087: }
1088: if (options.kbd_interactive_authentication) {
1089: error("Keyboard-interactive authentication is disabled"
1090: " to avoid man-in-the-middle attacks.");
1091: options.kbd_interactive_authentication = 0;
1092: options.challenge_response_authentication = 0;
1.210 dtucker 1093: cancelled_forwarding = 1;
1.144 djm 1094: }
1095: if (options.challenge_response_authentication) {
1096: error("Challenge/response authentication is disabled"
1097: " to avoid man-in-the-middle attacks.");
1098: options.challenge_response_authentication = 0;
1.210 dtucker 1099: cancelled_forwarding = 1;
1.38 markus 1100: }
1101: if (options.forward_agent) {
1.108 markus 1102: error("Agent forwarding is disabled to avoid "
1103: "man-in-the-middle attacks.");
1.38 markus 1104: options.forward_agent = 0;
1.210 dtucker 1105: cancelled_forwarding = 1;
1.83 markus 1106: }
1107: if (options.forward_x11) {
1.108 markus 1108: error("X11 forwarding is disabled to avoid "
1109: "man-in-the-middle attacks.");
1.83 markus 1110: options.forward_x11 = 0;
1.210 dtucker 1111: cancelled_forwarding = 1;
1.83 markus 1112: }
1.108 markus 1113: if (options.num_local_forwards > 0 ||
1114: options.num_remote_forwards > 0) {
1115: error("Port forwarding is disabled to avoid "
1116: "man-in-the-middle attacks.");
1117: options.num_local_forwards =
1.118 deraadt 1118: options.num_remote_forwards = 0;
1.210 dtucker 1119: cancelled_forwarding = 1;
1.194 stevesk 1120: }
1121: if (options.tun_open != SSH_TUNMODE_NO) {
1122: error("Tunnel forwarding is disabled to avoid "
1123: "man-in-the-middle attacks.");
1124: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1125: cancelled_forwarding = 1;
1.38 markus 1126: }
1.210 dtucker 1127: if (options.exit_on_forward_failure && cancelled_forwarding)
1128: fatal("Error: forwarding disabled due to host key "
1129: "check failure");
1130:
1.40 markus 1131: /*
1132: * XXX Should permit the user to change to use the new id.
1133: * This could be done by converting the host key to an
1134: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1135: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1136: * accept the authentication.
1137: */
1.38 markus 1138: break;
1.132 markus 1139: case HOST_FOUND:
1140: fatal("internal error");
1141: break;
1.88 markus 1142: }
1143:
1144: if (options.check_host_ip && host_status != HOST_CHANGED &&
1145: ip_status == HOST_CHANGED) {
1.119 markus 1146: snprintf(msg, sizeof(msg),
1147: "Warning: the %s host key for '%.200s' "
1148: "differs from the key for the IP address '%.128s'"
1.229 djm 1149: "\nOffending key for IP in %s:%lu",
1150: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1151: if (host_status == HOST_OK) {
1152: len = strlen(msg);
1153: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1154: "\nMatching host key in %s:%lu",
1155: host_found->file, host_found->line);
1.119 markus 1156: }
1.88 markus 1157: if (options.strict_host_key_checking == 1) {
1.143 djm 1158: logit("%s", msg);
1.108 markus 1159: error("Exiting, you have requested strict checking.");
1160: goto fail;
1.88 markus 1161: } else if (options.strict_host_key_checking == 2) {
1.119 markus 1162: strlcat(msg, "\nAre you sure you want "
1163: "to continue connecting (yes/no)? ", sizeof(msg));
1164: if (!confirm(msg))
1.108 markus 1165: goto fail;
1.119 markus 1166: } else {
1.143 djm 1167: logit("%s", msg);
1.88 markus 1168: }
1.257 djm 1169: }
1170:
1171: if (!hostkey_trusted && options.update_hostkeys) {
1172: debug("%s: hostkey not known or explicitly trusted: "
1173: "disabling UpdateHostkeys", __func__);
1174: options.update_hostkeys = 0;
1.38 markus 1175: }
1.82 provos 1176:
1.238 djm 1177: free(ip);
1178: free(host);
1.229 djm 1179: if (host_hostkeys != NULL)
1180: free_hostkeys(host_hostkeys);
1181: if (ip_hostkeys != NULL)
1182: free_hostkeys(ip_hostkeys);
1.108 markus 1183: return 0;
1184:
1185: fail:
1.220 djm 1186: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1187: /*
1188: * No matching certificate. Downgrade cert to raw key and
1189: * search normally.
1190: */
1191: debug("No matching CA found. Retry with plain key");
1192: raw_key = key_from_private(host_key);
1193: if (key_drop_cert(raw_key) != 0)
1194: fatal("Couldn't drop certificate");
1195: host_key = raw_key;
1196: goto retry;
1197: }
1198: if (raw_key != NULL)
1199: key_free(raw_key);
1.238 djm 1200: free(ip);
1201: free(host);
1.229 djm 1202: if (host_hostkeys != NULL)
1203: free_hostkeys(host_hostkeys);
1204: if (ip_hostkeys != NULL)
1205: free_hostkeys(ip_hostkeys);
1.108 markus 1206: return -1;
1207: }
1208:
1.140 jakob 1209: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1210: int
1211: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1212: {
1.250 djm 1213: int r = -1, flags = 0;
1.252 djm 1214: char *fp = NULL;
1215: struct sshkey *plain = NULL;
1.229 djm 1216:
1.252 djm 1217: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1218: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1219: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1220: r = -1;
1221: goto out;
1222: }
1223:
1.258 djm 1224: debug("Server host key: %s %s",
1225: compat20 ? sshkey_ssh_name(host_key) : sshkey_type(host_key), fp);
1.252 djm 1226:
1227: if (sshkey_equal(previous_host_key, host_key)) {
1228: debug2("%s: server host key %s %s matches cached key",
1229: __func__, sshkey_type(host_key), fp);
1230: r = 0;
1231: goto out;
1232: }
1233:
1234: /* Check in RevokedHostKeys file if specified */
1235: if (options.revoked_host_keys != NULL) {
1236: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1237: switch (r) {
1238: case 0:
1239: break; /* not revoked */
1240: case SSH_ERR_KEY_REVOKED:
1241: error("Host key %s %s revoked by file %s",
1242: sshkey_type(host_key), fp,
1243: options.revoked_host_keys);
1244: r = -1;
1245: goto out;
1246: default:
1247: error("Error checking host key %s %s in "
1248: "revoked keys file %s: %s", sshkey_type(host_key),
1249: fp, options.revoked_host_keys, ssh_err(r));
1250: r = -1;
1251: goto out;
1252: }
1.250 djm 1253: }
1254:
1.247 djm 1255: if (options.verify_host_key_dns) {
1256: /*
1257: * XXX certs are not yet supported for DNS, so downgrade
1258: * them and try the plain key.
1259: */
1.252 djm 1260: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1261: goto out;
1262: if (sshkey_is_cert(plain))
1263: sshkey_drop_cert(plain);
1.247 djm 1264: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1265: if (flags & DNS_VERIFY_FOUND) {
1266: if (options.verify_host_key_dns == 1 &&
1267: flags & DNS_VERIFY_MATCH &&
1268: flags & DNS_VERIFY_SECURE) {
1.250 djm 1269: r = 0;
1.252 djm 1270: goto out;
1.247 djm 1271: }
1272: if (flags & DNS_VERIFY_MATCH) {
1273: matching_host_key_dns = 1;
1274: } else {
1275: warn_changed_key(plain);
1276: error("Update the SSHFP RR in DNS "
1277: "with the new host key to get rid "
1278: "of this message.");
1279: }
1.153 jakob 1280: }
1.140 jakob 1281: }
1282: }
1.250 djm 1283: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1284: options.user_hostfiles, options.num_user_hostfiles,
1285: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1286:
1.252 djm 1287: out:
1288: sshkey_free(plain);
1289: free(fp);
1.250 djm 1290: if (r == 0 && host_key != NULL) {
1291: key_free(previous_host_key);
1292: previous_host_key = key_from_private(host_key);
1293: }
1294:
1295: return r;
1.51 markus 1296: }
1.70 markus 1297:
1.51 markus 1298: /*
1299: * Starts a dialog with the server, and authenticates the current user on the
1300: * server. This does not need any extra privileges. The basic connection
1301: * to the server must already have been established before this is called.
1302: * If login fails, this function prints an error and never returns.
1303: * This function does not require super-user privileges.
1304: */
1305: void
1.120 markus 1306: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1307: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1308: {
1.241 djm 1309: char *host;
1.70 markus 1310: char *server_user, *local_user;
1311:
1312: local_user = xstrdup(pw->pw_name);
1313: server_user = options.user ? options.user : local_user;
1.51 markus 1314:
1315: /* Convert the user-supplied hostname into all lowercase. */
1316: host = xstrdup(orighost);
1.241 djm 1317: lowercase(host);
1.51 markus 1318:
1319: /* Exchange protocol version identification strings with the server. */
1.202 djm 1320: ssh_exchange_identification(timeout_ms);
1.51 markus 1321:
1322: /* Put the connection into non-blocking mode. */
1323: packet_set_nonblocking();
1324:
1325: /* key exchange */
1326: /* authenticate user */
1.59 markus 1327: if (compat20) {
1.229 djm 1328: ssh_kex2(host, hostaddr, port);
1.120 markus 1329: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 1330: } else {
1.248 markus 1331: #ifdef WITH_SSH1
1.59 markus 1332: ssh_kex(host, hostaddr);
1.120 markus 1333: ssh_userauth1(local_user, server_user, host, sensitive);
1.248 markus 1334: #else
1.260 ! djm 1335: fatal("ssh1 is not supported");
1.248 markus 1336: #endif
1.59 markus 1337: }
1.238 djm 1338: free(local_user);
1.97 markus 1339: }
1340:
1341: void
1342: ssh_put_password(char *password)
1343: {
1344: int size;
1345: char *padded;
1346:
1.99 deraadt 1347: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1348: packet_put_cstring(password);
1.99 deraadt 1349: return;
1350: }
1.97 markus 1351: size = roundup(strlen(password) + 1, 32);
1.179 djm 1352: padded = xcalloc(1, size);
1.97 markus 1353: strlcpy(padded, password, size);
1354: packet_put_string(padded, size);
1.245 djm 1355: explicit_bzero(padded, size);
1.238 djm 1356: free(padded);
1.132 markus 1357: }
1358:
1359: /* print all known host keys for a given host, but skip keys of given type */
1360: static int
1.229 djm 1361: show_other_keys(struct hostkeys *hostkeys, Key *key)
1.132 markus 1362: {
1.242 djm 1363: int type[] = {
1364: KEY_RSA1,
1365: KEY_RSA,
1366: KEY_DSA,
1367: KEY_ECDSA,
1368: KEY_ED25519,
1369: -1
1370: };
1.229 djm 1371: int i, ret = 0;
1372: char *fp, *ra;
1373: const struct hostkey_entry *found;
1.132 markus 1374:
1375: for (i = 0; type[i] != -1; i++) {
1376: if (type[i] == key->type)
1377: continue;
1.229 djm 1378: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1379: continue;
1.259 djm 1380: fp = sshkey_fingerprint(found->key,
1.254 djm 1381: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1382: ra = sshkey_fingerprint(found->key,
1.254 djm 1383: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1384: if (fp == NULL || ra == NULL)
1385: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1386: logit("WARNING: %s key found for host %s\n"
1387: "in %s:%lu\n"
1388: "%s key fingerprint %s.",
1389: key_type(found->key),
1390: found->host, found->file, found->line,
1391: key_type(found->key), fp);
1392: if (options.visual_host_key)
1393: logit("%s", ra);
1.238 djm 1394: free(ra);
1395: free(fp);
1.229 djm 1396: ret = 1;
1.132 markus 1397: }
1.229 djm 1398: return ret;
1.150 jakob 1399: }
1400:
1401: static void
1402: warn_changed_key(Key *host_key)
1403: {
1404: char *fp;
1405:
1.259 djm 1406: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1407: SSH_FP_DEFAULT);
1.259 djm 1408: if (fp == NULL)
1409: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1410:
1411: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1412: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1413: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1414: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1415: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1416: error("It is also possible that a host key has just been changed.");
1.150 jakob 1417: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.230 markus 1418: key_type(host_key), fp);
1.150 jakob 1419: error("Please contact your system administrator.");
1420:
1.238 djm 1421: free(fp);
1.171 reyk 1422: }
1423:
1424: /*
1425: * Execute a local command
1426: */
1427: int
1428: ssh_local_cmd(const char *args)
1429: {
1430: char *shell;
1431: pid_t pid;
1432: int status;
1.231 djm 1433: void (*osighand)(int);
1.171 reyk 1434:
1435: if (!options.permit_local_command ||
1436: args == NULL || !*args)
1437: return (1);
1438:
1.226 djm 1439: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1440: shell = _PATH_BSHELL;
1441:
1.231 djm 1442: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1443: pid = fork();
1444: if (pid == 0) {
1.232 djm 1445: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1446: debug3("Executing %s -c \"%s\"", shell, args);
1447: execl(shell, shell, "-c", args, (char *)NULL);
1448: error("Couldn't execute %s -c \"%s\": %s",
1449: shell, args, strerror(errno));
1450: _exit(1);
1451: } else if (pid == -1)
1452: fatal("fork failed: %.100s", strerror(errno));
1453: while (waitpid(pid, &status, 0) == -1)
1454: if (errno != EINTR)
1455: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1456: signal(SIGCHLD, osighand);
1.171 reyk 1457:
1458: if (!WIFEXITED(status))
1459: return (1);
1460:
1461: return (WEXITSTATUS(status));
1.1 deraadt 1462: }
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