Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.271
1.271 ! markus 1: /* $OpenBSD: sshconnect.c,v 1.270 2016/01/14 16:17:40 markus Exp $ */
1.1 deraadt 2: /*
1.39 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
1.78 deraadt 8: *
9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 14: */
1.1 deraadt 15:
1.256 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"
1.239 djm 52: #include "monitor_fdpass.h"
1.219 djm 53: #include "ssh2.h"
1.186 stevesk 54: #include "version.h"
1.252 djm 55: #include "authfile.h"
56: #include "ssherr.h"
1.266 jcs 57: #include "authfd.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");
1.271 ! markus 160: close(sp[1]);
1.239 djm 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);
1.268 djm 427: memset(ntop, 0, sizeof(ntop));
428: memset(strport, 0, sizeof(strport));
1.38 markus 429:
1.181 markus 430: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 431: if (attempt > 0) {
432: /* Sleep a moment before retrying. */
433: sleep(1);
1.38 markus 434: debug("Trying again...");
1.200 markus 435: }
1.181 markus 436: /*
437: * Loop through addresses for this host, and try each one in
438: * sequence until the connection succeeds.
439: */
1.49 markus 440: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 441: if (ai->ai_family != AF_INET &&
442: ai->ai_family != AF_INET6)
1.49 markus 443: continue;
444: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
445: ntop, sizeof(ntop), strport, sizeof(strport),
446: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.265 djm 447: error("%s: getnameinfo failed", __func__);
1.49 markus 448: continue;
449: }
450: debug("Connecting to %.200s [%.100s] port %s.",
451: host, ntop, strport);
452:
453: /* Create a socket for connecting. */
1.139 markus 454: sock = ssh_create_socket(needpriv, ai);
1.49 markus 455: if (sock < 0)
1.110 markus 456: /* Any error is already output */
1.49 markus 457: continue;
458:
1.141 djm 459: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 460: timeout_ms) >= 0) {
1.49 markus 461: /* Successful connection. */
1.102 markus 462: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 463: break;
1.49 markus 464: } else {
1.131 itojun 465: debug("connect to address %s port %s: %s",
466: ntop, strport, strerror(errno));
1.38 markus 467: close(sock);
1.181 markus 468: sock = -1;
1.38 markus 469: }
470: }
1.181 markus 471: if (sock != -1)
1.49 markus 472: break; /* Successful connection. */
1.38 markus 473: }
1.49 markus 474:
1.38 markus 475: /* Return failure if we didn't get a successful connection. */
1.181 markus 476: if (sock == -1) {
1.159 markus 477: error("ssh: connect to host %s port %s: %s",
1.130 itojun 478: host, strport, strerror(errno));
1.159 markus 479: return (-1);
1.130 itojun 480: }
1.38 markus 481:
482: debug("Connection established.");
1.90 markus 483:
1.155 markus 484: /* Set SO_KEEPALIVE if requested. */
1.202 djm 485: if (want_keepalive &&
1.90 markus 486: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
487: sizeof(on)) < 0)
488: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 489:
490: /* Set the connection. */
491: packet_set_connection(sock, sock);
1.1 deraadt 492:
1.110 markus 493: return 0;
1.59 markus 494: }
495:
1.241 djm 496: int
497: ssh_connect(const char *host, struct addrinfo *addrs,
498: struct sockaddr_storage *hostaddr, u_short port, int family,
499: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
500: {
501: if (options.proxy_command == NULL) {
502: return ssh_connect_direct(host, addrs, hostaddr, port, family,
503: connection_attempts, timeout_ms, want_keepalive, needpriv);
504: } else if (strcmp(options.proxy_command, "-") == 0) {
505: packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
506: return 0; /* Always succeeds */
507: } else if (options.proxy_use_fdpass) {
508: return ssh_proxy_fdpass_connect(host, port,
509: options.proxy_command);
510: }
511: return ssh_proxy_connect(host, port, options.proxy_command);
512: }
513:
1.235 djm 514: static void
515: send_client_banner(int connection_out, int minor1)
516: {
517: /* Send our own protocol version identification. */
518: if (compat20) {
519: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
520: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
521: } else {
522: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n",
523: PROTOCOL_MAJOR_1, minor1, SSH_VERSION);
524: }
1.270 markus 525: if (atomicio(vwrite, connection_out, client_version_string,
1.235 djm 526: strlen(client_version_string)) != strlen(client_version_string))
527: fatal("write: %.100s", strerror(errno));
528: chop(client_version_string);
529: debug("Local version string %.100s", client_version_string);
530: }
531:
1.43 markus 532: /*
1.39 deraadt 533: * Waits for the server identification string, and sends our own
534: * identification string.
535: */
1.213 andreas 536: void
1.202 djm 537: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 538: {
1.38 markus 539: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 540: int remote_major, remote_minor, mismatch;
1.38 markus 541: int connection_in = packet_get_connection_in();
542: int connection_out = packet_get_connection_out();
1.235 djm 543: int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
1.185 djm 544: u_int i, n;
1.202 djm 545: size_t len;
546: int fdsetsz, remaining, rc;
547: struct timeval t_start, t_remaining;
548: fd_set *fdset;
549:
550: fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
551: fdset = xcalloc(1, fdsetsz);
1.38 markus 552:
1.235 djm 553: /*
554: * If we are SSH2-only then we can send the banner immediately and
555: * save a round-trip.
556: */
557: if (options.protocol == SSH_PROTO_2) {
558: enable_compat20();
559: send_client_banner(connection_out, 0);
560: client_banner_sent = 1;
561: }
562:
1.163 avsm 563: /* Read other side's version identification. */
1.202 djm 564: remaining = timeout_ms;
1.185 djm 565: for (n = 0;;) {
1.75 markus 566: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 567: if (timeout_ms > 0) {
568: gettimeofday(&t_start, NULL);
569: ms_to_timeval(&t_remaining, remaining);
570: FD_SET(connection_in, fdset);
571: rc = select(connection_in + 1, fdset, NULL,
572: fdset, &t_remaining);
573: ms_subtract_diff(&t_start, &remaining);
574: if (rc == 0 || remaining <= 0)
575: fatal("Connection timed out during "
576: "banner exchange");
577: if (rc == -1) {
578: if (errno == EINTR)
579: continue;
580: fatal("ssh_exchange_identification: "
581: "select: %s", strerror(errno));
582: }
583: }
584:
1.270 markus 585: len = atomicio(read, connection_in, &buf[i], 1);
1.163 avsm 586:
1.167 djm 587: if (len != 1 && errno == EPIPE)
1.202 djm 588: fatal("ssh_exchange_identification: "
589: "Connection closed by remote host");
1.163 avsm 590: else if (len != 1)
1.202 djm 591: fatal("ssh_exchange_identification: "
592: "read: %.100s", strerror(errno));
1.75 markus 593: if (buf[i] == '\r') {
594: buf[i] = '\n';
595: buf[i + 1] = 0;
596: continue; /**XXX wait for \n */
597: }
598: if (buf[i] == '\n') {
599: buf[i + 1] = 0;
600: break;
601: }
1.185 djm 602: if (++n > 65536)
1.202 djm 603: fatal("ssh_exchange_identification: "
604: "No banner received");
1.38 markus 605: }
1.75 markus 606: buf[sizeof(buf) - 1] = 0;
1.76 markus 607: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 608: break;
1.75 markus 609: debug("ssh_exchange_identification: %s", buf);
1.38 markus 610: }
1.59 markus 611: server_version_string = xstrdup(buf);
1.238 djm 612: free(fdset);
1.38 markus 613:
1.40 markus 614: /*
615: * Check that the versions match. In future this might accept
616: * several versions and set appropriate flags to handle them.
617: */
1.59 markus 618: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
619: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 620: fatal("Bad remote protocol version identification: '%.100s'", buf);
621: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 622: remote_major, remote_minor, remote_version);
1.38 markus 623:
1.255 markus 624: active_state->compat = compat_datafellows(remote_version);
1.64 markus 625: mismatch = 0;
1.59 markus 626:
1.116 deraadt 627: switch (remote_major) {
1.64 markus 628: case 1:
629: if (remote_minor == 99 &&
630: (options.protocol & SSH_PROTO_2) &&
631: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
632: enable_compat20();
633: break;
634: }
635: if (!(options.protocol & SSH_PROTO_1)) {
636: mismatch = 1;
637: break;
638: }
639: if (remote_minor < 3) {
640: fatal("Remote machine has too old SSH software version.");
1.81 markus 641: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 642: /* We speak 1.3, too. */
643: enable_compat13();
1.81 markus 644: minor1 = 3;
1.64 markus 645: if (options.forward_agent) {
1.138 itojun 646: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 647: options.forward_agent = 0;
648: }
649: }
650: break;
651: case 2:
652: if (options.protocol & SSH_PROTO_2) {
653: enable_compat20();
654: break;
1.38 markus 655: }
1.64 markus 656: /* FALLTHROUGH */
1.68 markus 657: default:
1.64 markus 658: mismatch = 1;
659: break;
1.38 markus 660: }
1.64 markus 661: if (mismatch)
1.38 markus 662: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 663: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
664: remote_major);
1.244 djm 665: if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
666: fatal("Server version \"%.100s\" uses unsafe key agreement; "
667: "refusing connection", remote_version);
1.243 djm 668: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
669: logit("Server version \"%.100s\" uses unsafe RSA signature "
670: "scheme; disabling use of RSA keys", remote_version);
1.235 djm 671: if (!client_banner_sent)
672: send_client_banner(connection_out, minor1);
1.59 markus 673: chop(server_version_string);
1.1 deraadt 674: }
675:
1.96 markus 676: /* defaults to 'no' */
1.109 itojun 677: static int
1.112 markus 678: confirm(const char *prompt)
1.1 deraadt 679: {
1.119 markus 680: const char *msg, *again = "Please type 'yes' or 'no': ";
681: char *p;
682: int ret = -1;
1.96 markus 683:
684: if (options.batch_mode)
685: return 0;
1.119 markus 686: for (msg = prompt;;msg = again) {
687: p = read_passphrase(msg, RP_ECHO);
688: if (p == NULL ||
689: (p[0] == '\0') || (p[0] == '\n') ||
690: strncasecmp(p, "no", 2) == 0)
691: ret = 0;
1.127 markus 692: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 693: ret = 1;
1.238 djm 694: free(p);
1.119 markus 695: if (ret != -1)
696: return ret;
1.1 deraadt 697: }
698: }
699:
1.219 djm 700: static int
701: check_host_cert(const char *host, const Key *host_key)
702: {
703: const char *reason;
704:
705: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
706: error("%s", reason);
707: return 0;
708: }
1.249 djm 709: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 710: error("Certificate for %s contains unsupported "
711: "critical options(s)", host);
1.219 djm 712: return 0;
713: }
714: return 1;
715: }
716:
1.229 djm 717: static int
718: sockaddr_is_local(struct sockaddr *hostaddr)
719: {
720: switch (hostaddr->sa_family) {
721: case AF_INET:
722: return (ntohl(((struct sockaddr_in *)hostaddr)->
723: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
724: case AF_INET6:
725: return IN6_IS_ADDR_LOOPBACK(
726: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
727: default:
728: return 0;
729: }
730: }
731:
732: /*
733: * Prepare the hostname and ip address strings that are used to lookup
734: * host keys in known_hosts files. These may have a port number appended.
735: */
736: void
737: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
738: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
739: {
740: char ntop[NI_MAXHOST];
741:
742: /*
743: * We don't have the remote ip-address for connections
744: * using a proxy command
745: */
746: if (hostfile_ipaddr != NULL) {
747: if (options.proxy_command == NULL) {
748: if (getnameinfo(hostaddr, hostaddr->sa_len,
749: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 750: fatal("%s: getnameinfo failed", __func__);
1.229 djm 751: *hostfile_ipaddr = put_host_port(ntop, port);
752: } else {
753: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
754: "command>");
755: }
756: }
757:
758: /*
759: * Allow the user to record the key under a different name or
760: * differentiate a non-standard port. This is useful for ssh
761: * tunneling over forwarded connections or if you run multiple
762: * sshd's on different ports on the same machine.
763: */
764: if (hostfile_hostname != NULL) {
765: if (options.host_key_alias != NULL) {
766: *hostfile_hostname = xstrdup(options.host_key_alias);
767: debug("using hostkeyalias: %s", *hostfile_hostname);
768: } else {
769: *hostfile_hostname = put_host_port(hostname, port);
770: }
771: }
772: }
773:
1.39 deraadt 774: /*
1.108 markus 775: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 776: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 777: */
1.197 dtucker 778: #define RDRW 0
779: #define RDONLY 1
780: #define ROQUIET 2
1.109 itojun 781: static int
1.197 dtucker 782: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.234 djm 783: Key *host_key, int readonly,
784: char **user_hostfiles, u_int num_user_hostfiles,
785: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 786: {
1.234 djm 787: HostStatus host_status;
788: HostStatus ip_status;
1.229 djm 789: Key *raw_key = NULL;
1.189 dtucker 790: char *ip = NULL, *host = NULL;
1.204 grunk 791: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 792: char msg[1024];
1.234 djm 793: const char *type;
794: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 795: int len, cancelled_forwarding = 0;
1.234 djm 796: int local = sockaddr_is_local(hostaddr);
797: int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
1.257 djm 798: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 799: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 800: u_int i;
1.49 markus 801:
802: /*
803: * Force accepting of the host key for loopback/localhost. The
804: * problem is that if the home directory is NFS-mounted to multiple
805: * machines, localhost will refer to a different machine in each of
806: * them, and the user will get bogus HOST_CHANGED warnings. This
807: * essentially disables host authentication for localhost; however,
808: * this is probably not a real problem.
809: */
1.111 markus 810: if (options.no_host_authentication_for_localhost == 1 && local &&
811: options.host_key_alias == NULL) {
1.88 markus 812: debug("Forcing accepting of host key for "
813: "loopback/localhost.");
1.108 markus 814: return 0;
1.49 markus 815: }
1.42 markus 816:
817: /*
1.229 djm 818: * Prepare the hostname and address strings used for hostkey lookup.
819: * In some cases, these will have a port number appended.
1.42 markus 820: */
1.229 djm 821: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 822:
823: /*
1.88 markus 824: * Turn off check_host_ip if the connection is to localhost, via proxy
825: * command or if we don't have a hostname to compare with
826: */
1.189 dtucker 827: if (options.check_host_ip && (local ||
828: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 829: options.check_host_ip = 0;
1.86 markus 830:
1.229 djm 831: host_hostkeys = init_hostkeys();
1.234 djm 832: for (i = 0; i < num_user_hostfiles; i++)
833: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
834: for (i = 0; i < num_system_hostfiles; i++)
835: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 836:
837: ip_hostkeys = NULL;
838: if (!want_cert && options.check_host_ip) {
839: ip_hostkeys = init_hostkeys();
1.234 djm 840: for (i = 0; i < num_user_hostfiles; i++)
841: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
842: for (i = 0; i < num_system_hostfiles; i++)
843: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 844: }
1.38 markus 845:
1.219 djm 846: retry:
1.229 djm 847: /* Reload these as they may have changed on cert->key downgrade */
1.219 djm 848: want_cert = key_is_cert(host_key);
849: type = key_type(host_key);
850:
1.46 markus 851: /*
1.170 djm 852: * Check if the host key is present in the user's list of known
1.40 markus 853: * hosts or in the systemwide list.
854: */
1.229 djm 855: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
856: &host_found);
857:
1.40 markus 858: /*
859: * Also perform check for the ip address, skip the check if we are
1.219 djm 860: * localhost, looking for a certificate, or the hostname was an ip
861: * address to begin with.
1.40 markus 862: */
1.229 djm 863: if (!want_cert && ip_hostkeys != NULL) {
864: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
865: &ip_found);
1.38 markus 866: if (host_status == HOST_CHANGED &&
1.229 djm 867: (ip_status != HOST_CHANGED ||
868: (ip_found != NULL &&
869: !key_equal(ip_found->key, host_found->key))))
1.38 markus 870: host_ip_differ = 1;
871: } else
872: ip_status = host_status;
873:
874: switch (host_status) {
875: case HOST_OK:
876: /* The host is known and the key matches. */
1.219 djm 877: debug("Host '%.200s' is known and matches the %s host %s.",
878: host, type, want_cert ? "certificate" : "key");
1.229 djm 879: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
880: host_found->file, host_found->line);
1.219 djm 881: if (want_cert && !check_host_cert(hostname, host_key))
882: goto fail;
1.88 markus 883: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 884: if (readonly || want_cert)
1.138 itojun 885: logit("%s host key for IP address "
1.108 markus 886: "'%.128s' not in list of known hosts.",
887: type, ip);
1.234 djm 888: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 889: host_key, options.hash_known_hosts))
1.138 itojun 890: logit("Failed to add the %s host key for IP "
1.108 markus 891: "address '%.128s' to the list of known "
1.262 dtucker 892: "hosts (%.500s).", type, ip,
1.234 djm 893: user_hostfiles[0]);
1.88 markus 894: else
1.138 itojun 895: logit("Warning: Permanently added the %s host "
1.108 markus 896: "key for IP address '%.128s' to the list "
897: "of known hosts.", type, ip);
1.209 grunk 898: } else if (options.visual_host_key) {
1.259 djm 899: fp = sshkey_fingerprint(host_key,
1.254 djm 900: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 901: ra = sshkey_fingerprint(host_key,
1.254 djm 902: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 903: if (fp == NULL || ra == NULL)
904: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 905: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 906: free(ra);
907: free(fp);
1.38 markus 908: }
1.257 djm 909: hostkey_trusted = 1;
1.38 markus 910: break;
911: case HOST_NEW:
1.197 dtucker 912: if (options.host_key_alias == NULL && port != 0 &&
913: port != SSH_DEFAULT_PORT) {
914: debug("checking without port identifier");
1.212 stevesk 915: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 916: ROQUIET, user_hostfiles, num_user_hostfiles,
917: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 918: debug("found matching key w/out port");
919: break;
920: }
921: }
1.219 djm 922: if (readonly || want_cert)
1.108 markus 923: goto fail;
1.38 markus 924: /* The host is new. */
925: if (options.strict_host_key_checking == 1) {
1.108 markus 926: /*
927: * User has requested strict host key checking. We
928: * will not add the host key automatically. The only
929: * alternative left is to abort.
930: */
931: error("No %s host key is known for %.200s and you "
932: "have requested strict checking.", type, host);
933: goto fail;
1.38 markus 934: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 935: char msg1[1024], msg2[1024];
936:
1.229 djm 937: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 938: snprintf(msg1, sizeof(msg1),
1.168 djm 939: "\nbut keys of different type are already"
940: " known for this host.");
1.145 jakob 941: else
942: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 943: /* The default */
1.259 djm 944: fp = sshkey_fingerprint(host_key,
1.254 djm 945: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 946: ra = sshkey_fingerprint(host_key,
1.254 djm 947: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 948: if (fp == NULL || ra == NULL)
949: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 950: msg2[0] = '\0';
951: if (options.verify_host_key_dns) {
1.153 jakob 952: if (matching_host_key_dns)
1.145 jakob 953: snprintf(msg2, sizeof(msg2),
954: "Matching host key fingerprint"
955: " found in DNS.\n");
956: else
957: snprintf(msg2, sizeof(msg2),
958: "No matching host key fingerprint"
959: " found in DNS.\n");
960: }
1.119 markus 961: snprintf(msg, sizeof(msg),
1.108 markus 962: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 963: "established%s\n"
1.209 grunk 964: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 965: "Are you sure you want to continue connecting "
1.132 markus 966: "(yes/no)? ",
1.209 grunk 967: host, ip, msg1, type, fp,
968: options.visual_host_key ? "\n" : "",
969: options.visual_host_key ? ra : "",
970: msg2);
1.238 djm 971: free(ra);
972: free(fp);
1.119 markus 973: if (!confirm(msg))
1.108 markus 974: goto fail;
1.257 djm 975: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 976: }
1.161 djm 977: /*
978: * If not in strict mode, add the key automatically to the
979: * local known_hosts file.
980: */
1.88 markus 981: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 982: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 983: hostp = hostline;
1.161 djm 984: if (options.hash_known_hosts) {
985: /* Add hash of host and IP separately */
1.234 djm 986: r = add_host_to_hostfile(user_hostfiles[0],
987: host, host_key, options.hash_known_hosts) &&
988: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 989: host_key, options.hash_known_hosts);
990: } else {
991: /* Add unhashed "host,ip" */
1.234 djm 992: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 993: hostline, host_key,
994: options.hash_known_hosts);
995: }
996: } else {
1.234 djm 997: r = add_host_to_hostfile(user_hostfiles[0], host,
998: host_key, options.hash_known_hosts);
1.38 markus 999: hostp = host;
1.161 djm 1000: }
1.38 markus 1001:
1.161 djm 1002: if (!r)
1.138 itojun 1003: logit("Failed to add the host to the list of known "
1.234 djm 1004: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 1005: else
1.138 itojun 1006: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 1007: "list of known hosts.", hostp, type);
1.38 markus 1008: break;
1.220 djm 1009: case HOST_REVOKED:
1010: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1011: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1012: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1013: error("The %s host key for %s is marked as revoked.", type, host);
1014: error("This could mean that a stolen key is being used to");
1015: error("impersonate this host.");
1016:
1017: /*
1018: * If strict host key checking is in use, the user will have
1019: * to edit the key manually and we can only abort.
1020: */
1021: if (options.strict_host_key_checking) {
1022: error("%s host key for %.200s was revoked and you have "
1023: "requested strict checking.", type, host);
1024: goto fail;
1025: }
1026: goto continue_unsafe;
1027:
1.38 markus 1028: case HOST_CHANGED:
1.219 djm 1029: if (want_cert) {
1030: /*
1031: * This is only a debug() since it is valid to have
1032: * CAs with wildcard DNS matches that don't match
1033: * all hosts that one might visit.
1034: */
1035: debug("Host certificate authority does not "
1.229 djm 1036: "match %s in %s:%lu", CA_MARKER,
1037: host_found->file, host_found->line);
1.219 djm 1038: goto fail;
1039: }
1.197 dtucker 1040: if (readonly == ROQUIET)
1041: goto fail;
1.38 markus 1042: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1043: char *key_msg;
1.38 markus 1044: if (ip_status == HOST_NEW)
1.158 avsm 1045: key_msg = "is unknown";
1.38 markus 1046: else if (ip_status == HOST_OK)
1.158 avsm 1047: key_msg = "is unchanged";
1.38 markus 1048: else
1.158 avsm 1049: key_msg = "has a different value";
1.38 markus 1050: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1051: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1052: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1053: error("The %s host key for %s has changed,", type, host);
1.208 ian 1054: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1055: error("%s. This could either mean that", key_msg);
1.38 markus 1056: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1057: error("and its host key have changed at the same time.");
1.88 markus 1058: if (ip_status != HOST_NEW)
1.229 djm 1059: error("Offending key for IP in %s:%lu",
1060: ip_found->file, ip_found->line);
1.38 markus 1061: }
1062: /* The host key has changed. */
1.150 jakob 1063: warn_changed_key(host_key);
1.38 markus 1064: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1065: user_hostfiles[0]);
1.229 djm 1066: error("Offending %s key in %s:%lu", key_type(host_found->key),
1067: host_found->file, host_found->line);
1.38 markus 1068:
1.40 markus 1069: /*
1070: * If strict host key checking is in use, the user will have
1071: * to edit the key manually and we can only abort.
1072: */
1.108 markus 1073: if (options.strict_host_key_checking) {
1074: error("%s host key for %.200s has changed and you have "
1075: "requested strict checking.", type, host);
1076: goto fail;
1077: }
1.38 markus 1078:
1.220 djm 1079: continue_unsafe:
1.40 markus 1080: /*
1081: * If strict host key checking has not been requested, allow
1.144 djm 1082: * the connection but without MITM-able authentication or
1.194 stevesk 1083: * forwarding.
1.40 markus 1084: */
1.38 markus 1085: if (options.password_authentication) {
1.108 markus 1086: error("Password authentication is disabled to avoid "
1087: "man-in-the-middle attacks.");
1.38 markus 1088: options.password_authentication = 0;
1.210 dtucker 1089: cancelled_forwarding = 1;
1.144 djm 1090: }
1091: if (options.kbd_interactive_authentication) {
1092: error("Keyboard-interactive authentication is disabled"
1093: " to avoid man-in-the-middle attacks.");
1094: options.kbd_interactive_authentication = 0;
1095: options.challenge_response_authentication = 0;
1.210 dtucker 1096: cancelled_forwarding = 1;
1.144 djm 1097: }
1098: if (options.challenge_response_authentication) {
1099: error("Challenge/response authentication is disabled"
1100: " to avoid man-in-the-middle attacks.");
1101: options.challenge_response_authentication = 0;
1.210 dtucker 1102: cancelled_forwarding = 1;
1.38 markus 1103: }
1104: if (options.forward_agent) {
1.108 markus 1105: error("Agent forwarding is disabled to avoid "
1106: "man-in-the-middle attacks.");
1.38 markus 1107: options.forward_agent = 0;
1.210 dtucker 1108: cancelled_forwarding = 1;
1.83 markus 1109: }
1110: if (options.forward_x11) {
1.108 markus 1111: error("X11 forwarding is disabled to avoid "
1112: "man-in-the-middle attacks.");
1.83 markus 1113: options.forward_x11 = 0;
1.210 dtucker 1114: cancelled_forwarding = 1;
1.83 markus 1115: }
1.108 markus 1116: if (options.num_local_forwards > 0 ||
1117: options.num_remote_forwards > 0) {
1118: error("Port forwarding is disabled to avoid "
1119: "man-in-the-middle attacks.");
1120: options.num_local_forwards =
1.118 deraadt 1121: options.num_remote_forwards = 0;
1.210 dtucker 1122: cancelled_forwarding = 1;
1.194 stevesk 1123: }
1124: if (options.tun_open != SSH_TUNMODE_NO) {
1125: error("Tunnel forwarding is disabled to avoid "
1126: "man-in-the-middle attacks.");
1127: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1128: cancelled_forwarding = 1;
1.38 markus 1129: }
1.210 dtucker 1130: if (options.exit_on_forward_failure && cancelled_forwarding)
1131: fatal("Error: forwarding disabled due to host key "
1132: "check failure");
1133:
1.40 markus 1134: /*
1135: * XXX Should permit the user to change to use the new id.
1136: * This could be done by converting the host key to an
1137: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1138: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1139: * accept the authentication.
1140: */
1.38 markus 1141: break;
1.132 markus 1142: case HOST_FOUND:
1143: fatal("internal error");
1144: break;
1.88 markus 1145: }
1146:
1147: if (options.check_host_ip && host_status != HOST_CHANGED &&
1148: ip_status == HOST_CHANGED) {
1.119 markus 1149: snprintf(msg, sizeof(msg),
1150: "Warning: the %s host key for '%.200s' "
1151: "differs from the key for the IP address '%.128s'"
1.229 djm 1152: "\nOffending key for IP in %s:%lu",
1153: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1154: if (host_status == HOST_OK) {
1155: len = strlen(msg);
1156: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1157: "\nMatching host key in %s:%lu",
1158: host_found->file, host_found->line);
1.119 markus 1159: }
1.88 markus 1160: if (options.strict_host_key_checking == 1) {
1.143 djm 1161: logit("%s", msg);
1.108 markus 1162: error("Exiting, you have requested strict checking.");
1163: goto fail;
1.88 markus 1164: } else if (options.strict_host_key_checking == 2) {
1.119 markus 1165: strlcat(msg, "\nAre you sure you want "
1166: "to continue connecting (yes/no)? ", sizeof(msg));
1167: if (!confirm(msg))
1.108 markus 1168: goto fail;
1.119 markus 1169: } else {
1.143 djm 1170: logit("%s", msg);
1.88 markus 1171: }
1.257 djm 1172: }
1173:
1174: if (!hostkey_trusted && options.update_hostkeys) {
1175: debug("%s: hostkey not known or explicitly trusted: "
1176: "disabling UpdateHostkeys", __func__);
1177: options.update_hostkeys = 0;
1.38 markus 1178: }
1.82 provos 1179:
1.238 djm 1180: free(ip);
1181: free(host);
1.229 djm 1182: if (host_hostkeys != NULL)
1183: free_hostkeys(host_hostkeys);
1184: if (ip_hostkeys != NULL)
1185: free_hostkeys(ip_hostkeys);
1.108 markus 1186: return 0;
1187:
1188: fail:
1.220 djm 1189: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1190: /*
1191: * No matching certificate. Downgrade cert to raw key and
1192: * search normally.
1193: */
1194: debug("No matching CA found. Retry with plain key");
1195: raw_key = key_from_private(host_key);
1196: if (key_drop_cert(raw_key) != 0)
1197: fatal("Couldn't drop certificate");
1198: host_key = raw_key;
1199: goto retry;
1200: }
1201: if (raw_key != NULL)
1202: key_free(raw_key);
1.238 djm 1203: free(ip);
1204: free(host);
1.229 djm 1205: if (host_hostkeys != NULL)
1206: free_hostkeys(host_hostkeys);
1207: if (ip_hostkeys != NULL)
1208: free_hostkeys(ip_hostkeys);
1.108 markus 1209: return -1;
1210: }
1211:
1.140 jakob 1212: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1213: int
1214: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1215: {
1.267 djm 1216: u_int i;
1.250 djm 1217: int r = -1, flags = 0;
1.267 djm 1218: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1219: struct sshkey *plain = NULL;
1.229 djm 1220:
1.252 djm 1221: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1222: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1223: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1224: r = -1;
1225: goto out;
1226: }
1227:
1.267 djm 1228: if (sshkey_is_cert(host_key)) {
1229: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1230: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1231: error("%s: fingerprint CA key: %s",
1232: __func__, ssh_err(r));
1233: r = -1;
1234: goto out;
1235: }
1236: sshkey_format_cert_validity(host_key->cert,
1237: valid, sizeof(valid));
1238: debug("Server host certificate: %s %s, serial %llu "
1239: "ID \"%s\" CA %s %s valid %s",
1240: sshkey_ssh_name(host_key), fp,
1.269 djm 1241: (unsigned long long)host_key->cert->serial,
1242: host_key->cert->key_id,
1.267 djm 1243: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1244: valid);
1245: for (i = 0; i < host_key->cert->nprincipals; i++) {
1246: debug2("Server host certificate hostname: %s",
1247: host_key->cert->principals[i]);
1248: }
1249: } else {
1250: debug("Server host key: %s %s", compat20 ?
1251: sshkey_ssh_name(host_key) : sshkey_type(host_key), fp);
1252: }
1.252 djm 1253:
1254: if (sshkey_equal(previous_host_key, host_key)) {
1255: debug2("%s: server host key %s %s matches cached key",
1256: __func__, sshkey_type(host_key), fp);
1257: r = 0;
1258: goto out;
1259: }
1260:
1261: /* Check in RevokedHostKeys file if specified */
1262: if (options.revoked_host_keys != NULL) {
1263: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1264: switch (r) {
1265: case 0:
1266: break; /* not revoked */
1267: case SSH_ERR_KEY_REVOKED:
1268: error("Host key %s %s revoked by file %s",
1269: sshkey_type(host_key), fp,
1270: options.revoked_host_keys);
1271: r = -1;
1272: goto out;
1273: default:
1274: error("Error checking host key %s %s in "
1275: "revoked keys file %s: %s", sshkey_type(host_key),
1276: fp, options.revoked_host_keys, ssh_err(r));
1277: r = -1;
1278: goto out;
1279: }
1.250 djm 1280: }
1281:
1.247 djm 1282: if (options.verify_host_key_dns) {
1283: /*
1284: * XXX certs are not yet supported for DNS, so downgrade
1285: * them and try the plain key.
1286: */
1.252 djm 1287: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1288: goto out;
1289: if (sshkey_is_cert(plain))
1290: sshkey_drop_cert(plain);
1.247 djm 1291: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1292: if (flags & DNS_VERIFY_FOUND) {
1293: if (options.verify_host_key_dns == 1 &&
1294: flags & DNS_VERIFY_MATCH &&
1295: flags & DNS_VERIFY_SECURE) {
1.250 djm 1296: r = 0;
1.252 djm 1297: goto out;
1.247 djm 1298: }
1299: if (flags & DNS_VERIFY_MATCH) {
1300: matching_host_key_dns = 1;
1301: } else {
1302: warn_changed_key(plain);
1303: error("Update the SSHFP RR in DNS "
1304: "with the new host key to get rid "
1305: "of this message.");
1306: }
1.153 jakob 1307: }
1.140 jakob 1308: }
1309: }
1.250 djm 1310: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1311: options.user_hostfiles, options.num_user_hostfiles,
1312: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1313:
1.252 djm 1314: out:
1315: sshkey_free(plain);
1316: free(fp);
1.267 djm 1317: free(cafp);
1.250 djm 1318: if (r == 0 && host_key != NULL) {
1319: key_free(previous_host_key);
1320: previous_host_key = key_from_private(host_key);
1321: }
1322:
1323: return r;
1.51 markus 1324: }
1.70 markus 1325:
1.51 markus 1326: /*
1327: * Starts a dialog with the server, and authenticates the current user on the
1328: * server. This does not need any extra privileges. The basic connection
1329: * to the server must already have been established before this is called.
1330: * If login fails, this function prints an error and never returns.
1331: * This function does not require super-user privileges.
1332: */
1333: void
1.120 markus 1334: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1335: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1336: {
1.241 djm 1337: char *host;
1.70 markus 1338: char *server_user, *local_user;
1339:
1340: local_user = xstrdup(pw->pw_name);
1341: server_user = options.user ? options.user : local_user;
1.51 markus 1342:
1343: /* Convert the user-supplied hostname into all lowercase. */
1344: host = xstrdup(orighost);
1.241 djm 1345: lowercase(host);
1.51 markus 1346:
1347: /* Exchange protocol version identification strings with the server. */
1.202 djm 1348: ssh_exchange_identification(timeout_ms);
1.51 markus 1349:
1350: /* Put the connection into non-blocking mode. */
1351: packet_set_nonblocking();
1352:
1353: /* key exchange */
1354: /* authenticate user */
1.261 dtucker 1355: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.59 markus 1356: if (compat20) {
1.229 djm 1357: ssh_kex2(host, hostaddr, port);
1.120 markus 1358: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 1359: } else {
1.248 markus 1360: #ifdef WITH_SSH1
1.59 markus 1361: ssh_kex(host, hostaddr);
1.120 markus 1362: ssh_userauth1(local_user, server_user, host, sensitive);
1.248 markus 1363: #else
1.260 djm 1364: fatal("ssh1 is not supported");
1.248 markus 1365: #endif
1.59 markus 1366: }
1.238 djm 1367: free(local_user);
1.97 markus 1368: }
1369:
1370: void
1371: ssh_put_password(char *password)
1372: {
1373: int size;
1374: char *padded;
1375:
1.99 deraadt 1376: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1377: packet_put_cstring(password);
1.99 deraadt 1378: return;
1379: }
1.97 markus 1380: size = roundup(strlen(password) + 1, 32);
1.179 djm 1381: padded = xcalloc(1, size);
1.97 markus 1382: strlcpy(padded, password, size);
1383: packet_put_string(padded, size);
1.245 djm 1384: explicit_bzero(padded, size);
1.238 djm 1385: free(padded);
1.132 markus 1386: }
1387:
1388: /* print all known host keys for a given host, but skip keys of given type */
1389: static int
1.229 djm 1390: show_other_keys(struct hostkeys *hostkeys, Key *key)
1.132 markus 1391: {
1.242 djm 1392: int type[] = {
1393: KEY_RSA1,
1394: KEY_RSA,
1395: KEY_DSA,
1396: KEY_ECDSA,
1397: KEY_ED25519,
1398: -1
1399: };
1.229 djm 1400: int i, ret = 0;
1401: char *fp, *ra;
1402: const struct hostkey_entry *found;
1.132 markus 1403:
1404: for (i = 0; type[i] != -1; i++) {
1405: if (type[i] == key->type)
1406: continue;
1.229 djm 1407: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1408: continue;
1.259 djm 1409: fp = sshkey_fingerprint(found->key,
1.254 djm 1410: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1411: ra = sshkey_fingerprint(found->key,
1.254 djm 1412: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1413: if (fp == NULL || ra == NULL)
1414: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1415: logit("WARNING: %s key found for host %s\n"
1416: "in %s:%lu\n"
1417: "%s key fingerprint %s.",
1418: key_type(found->key),
1419: found->host, found->file, found->line,
1420: key_type(found->key), fp);
1421: if (options.visual_host_key)
1422: logit("%s", ra);
1.238 djm 1423: free(ra);
1424: free(fp);
1.229 djm 1425: ret = 1;
1.132 markus 1426: }
1.229 djm 1427: return ret;
1.150 jakob 1428: }
1429:
1430: static void
1431: warn_changed_key(Key *host_key)
1432: {
1433: char *fp;
1434:
1.259 djm 1435: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1436: SSH_FP_DEFAULT);
1.259 djm 1437: if (fp == NULL)
1438: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1439:
1440: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1441: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1442: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1443: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1444: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1445: error("It is also possible that a host key has just been changed.");
1.150 jakob 1446: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.230 markus 1447: key_type(host_key), fp);
1.150 jakob 1448: error("Please contact your system administrator.");
1449:
1.238 djm 1450: free(fp);
1.171 reyk 1451: }
1452:
1453: /*
1454: * Execute a local command
1455: */
1456: int
1457: ssh_local_cmd(const char *args)
1458: {
1459: char *shell;
1460: pid_t pid;
1461: int status;
1.231 djm 1462: void (*osighand)(int);
1.171 reyk 1463:
1464: if (!options.permit_local_command ||
1465: args == NULL || !*args)
1466: return (1);
1467:
1.226 djm 1468: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1469: shell = _PATH_BSHELL;
1470:
1.231 djm 1471: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1472: pid = fork();
1473: if (pid == 0) {
1.232 djm 1474: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1475: debug3("Executing %s -c \"%s\"", shell, args);
1476: execl(shell, shell, "-c", args, (char *)NULL);
1477: error("Couldn't execute %s -c \"%s\": %s",
1478: shell, args, strerror(errno));
1479: _exit(1);
1480: } else if (pid == -1)
1481: fatal("fork failed: %.100s", strerror(errno));
1482: while (waitpid(pid, &status, 0) == -1)
1483: if (errno != EINTR)
1484: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1485: signal(SIGCHLD, osighand);
1.171 reyk 1486:
1487: if (!WIFEXITED(status))
1488: return (1);
1489:
1490: return (WEXITSTATUS(status));
1.266 jcs 1491: }
1492:
1493: void
1494: maybe_add_key_to_agent(char *authfile, Key *private, char *comment,
1495: char *passphrase)
1496: {
1497: int auth_sock = -1, r;
1498:
1499: if (options.add_keys_to_agent == 0)
1500: return;
1501:
1502: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1503: debug3("no authentication agent, not adding key");
1504: return;
1505: }
1506:
1507: if (options.add_keys_to_agent == 2 &&
1508: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1509: debug3("user denied adding this key");
1510: return;
1511: }
1512:
1513: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1514: (options.add_keys_to_agent == 3))) == 0)
1515: debug("identity added to agent: %s", authfile);
1516: else
1517: debug("could not add identity to agent: %s (%d)", authfile, r);
1.1 deraadt 1518: }
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