Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.251
1.251 ! millert 1: /* $OpenBSD: sshconnect.c,v 1.250 2014/07/03 22:23:46 djm Exp $ */
1.1 deraadt 2: /*
1.39 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
1.78 deraadt 8: *
9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 14: */
1.1 deraadt 15:
1.174 stevesk 16: #include <sys/types.h>
17: #include <sys/wait.h>
1.175 stevesk 18: #include <sys/stat.h>
1.187 stevesk 19: #include <sys/socket.h>
1.195 stevesk 20: #include <sys/time.h>
1.187 stevesk 21:
22: #include <netinet/in.h>
1.172 stevesk 23:
1.176 stevesk 24: #include <ctype.h>
1.190 stevesk 25: #include <errno.h>
1.216 dtucker 26: #include <fcntl.h>
1.191 stevesk 27: #include <netdb.h>
1.172 stevesk 28: #include <paths.h>
1.199 deraadt 29: #include <signal.h>
1.188 stevesk 30: #include <pwd.h>
1.198 stevesk 31: #include <stdio.h>
1.196 stevesk 32: #include <stdlib.h>
1.193 stevesk 33: #include <string.h>
1.192 stevesk 34: #include <unistd.h>
1.71 markus 35:
1.199 deraadt 36: #include "xmalloc.h"
1.91 markus 37: #include "ssh.h"
1.1 deraadt 38: #include "rsa.h"
1.59 markus 39: #include "buffer.h"
1.1 deraadt 40: #include "packet.h"
41: #include "uidswap.h"
1.21 markus 42: #include "compat.h"
1.58 markus 43: #include "key.h"
1.71 markus 44: #include "sshconnect.h"
1.58 markus 45: #include "hostfile.h"
1.91 markus 46: #include "log.h"
1.251 ! millert 47: #include "misc.h"
1.91 markus 48: #include "readconf.h"
49: #include "atomicio.h"
1.140 jakob 50: #include "dns.h"
1.214 andreas 51: #include "roaming.h"
1.239 djm 52: #include "monitor_fdpass.h"
1.219 djm 53: #include "ssh2.h"
1.186 stevesk 54: #include "version.h"
1.140 jakob 55:
1.70 markus 56: char *client_version_string = NULL;
57: char *server_version_string = NULL;
1.250 djm 58: Key *previous_host_key = NULL;
1.59 markus 59:
1.169 stevesk 60: static int matching_host_key_dns = 0;
1.145 jakob 61:
1.227 djm 62: static pid_t proxy_command_pid = 0;
63:
1.124 markus 64: /* import */
1.43 markus 65: extern Options options;
1.50 markus 66: extern char *__progname;
1.124 markus 67: extern uid_t original_real_uid;
68: extern uid_t original_effective_uid;
1.91 markus 69:
1.229 djm 70: static int show_other_keys(struct hostkeys *, Key *);
1.150 jakob 71: static void warn_changed_key(Key *);
1.132 markus 72:
1.239 djm 73: /* Expand a proxy command */
74: static char *
75: expand_proxy_command(const char *proxy_command, const char *user,
76: const char *host, int port)
77: {
78: char *tmp, *ret, strport[NI_MAXSERV];
79:
1.241 djm 80: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 81: xasprintf(&tmp, "exec %s", proxy_command);
82: ret = percent_expand(tmp, "h", host, "p", strport,
83: "r", options.user, (char *)NULL);
84: free(tmp);
85: return ret;
86: }
87:
88: /*
89: * Connect to the given ssh server using a proxy command that passes a
90: * a connected fd back to us.
91: */
92: static int
93: ssh_proxy_fdpass_connect(const char *host, u_short port,
94: const char *proxy_command)
95: {
96: char *command_string;
97: int sp[2], sock;
98: pid_t pid;
99: char *shell;
100:
101: if ((shell = getenv("SHELL")) == NULL)
102: shell = _PATH_BSHELL;
103:
104: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
105: fatal("Could not create socketpair to communicate with "
106: "proxy dialer: %.100s", strerror(errno));
107:
108: command_string = expand_proxy_command(proxy_command, options.user,
109: host, port);
110: debug("Executing proxy dialer command: %.500s", command_string);
111:
112: /* Fork and execute the proxy command. */
113: if ((pid = fork()) == 0) {
114: char *argv[10];
115:
116: /* Child. Permanently give up superuser privileges. */
117: permanently_drop_suid(original_real_uid);
118:
119: close(sp[1]);
120: /* Redirect stdin and stdout. */
121: if (sp[0] != 0) {
122: if (dup2(sp[0], 0) < 0)
123: perror("dup2 stdin");
124: }
125: if (sp[0] != 1) {
126: if (dup2(sp[0], 1) < 0)
127: perror("dup2 stdout");
128: }
129: if (sp[0] >= 2)
130: close(sp[0]);
131:
132: /*
133: * Stderr is left as it is so that error messages get
134: * printed on the user's terminal.
135: */
136: argv[0] = shell;
137: argv[1] = "-c";
138: argv[2] = command_string;
139: argv[3] = NULL;
140:
141: /*
142: * Execute the proxy command.
143: * Note that we gave up any extra privileges above.
144: */
145: execv(argv[0], argv);
146: perror(argv[0]);
147: exit(1);
148: }
149: /* Parent. */
150: if (pid < 0)
151: fatal("fork failed: %.100s", strerror(errno));
152: close(sp[0]);
153: free(command_string);
154:
155: if ((sock = mm_receive_fd(sp[1])) == -1)
156: fatal("proxy dialer did not pass back a connection");
157:
158: while (waitpid(pid, NULL, 0) == -1)
159: if (errno != EINTR)
160: fatal("Couldn't wait for child: %s", strerror(errno));
161:
162: /* Set the connection file descriptors. */
163: packet_set_connection(sock, sock);
164:
165: return 0;
166: }
167:
1.39 deraadt 168: /*
169: * Connect to the given ssh server using a proxy command.
170: */
1.109 itojun 171: static int
1.124 markus 172: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 173: {
1.239 djm 174: char *command_string;
1.38 markus 175: int pin[2], pout[2];
1.69 deraadt 176: pid_t pid;
1.239 djm 177: char *shell;
1.237 markus 178:
1.226 djm 179: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 180: shell = _PATH_BSHELL;
1.38 markus 181:
182: /* Create pipes for communicating with the proxy. */
183: if (pipe(pin) < 0 || pipe(pout) < 0)
184: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 185: strerror(errno));
1.38 markus 186:
1.239 djm 187: command_string = expand_proxy_command(proxy_command, options.user,
188: host, port);
1.38 markus 189: debug("Executing proxy command: %.500s", command_string);
190:
191: /* Fork and execute the proxy command. */
192: if ((pid = fork()) == 0) {
193: char *argv[10];
194:
195: /* Child. Permanently give up superuser privileges. */
1.184 markus 196: permanently_drop_suid(original_real_uid);
1.38 markus 197:
198: /* Redirect stdin and stdout. */
199: close(pin[1]);
200: if (pin[0] != 0) {
201: if (dup2(pin[0], 0) < 0)
202: perror("dup2 stdin");
203: close(pin[0]);
204: }
205: close(pout[0]);
206: if (dup2(pout[1], 1) < 0)
207: perror("dup2 stdout");
208: /* Cannot be 1 because pin allocated two descriptors. */
209: close(pout[1]);
210:
211: /* Stderr is left as it is so that error messages get
212: printed on the user's terminal. */
1.201 djm 213: argv[0] = shell;
1.38 markus 214: argv[1] = "-c";
215: argv[2] = command_string;
216: argv[3] = NULL;
217:
218: /* Execute the proxy command. Note that we gave up any
219: extra privileges above. */
1.232 djm 220: signal(SIGPIPE, SIG_DFL);
1.89 markus 221: execv(argv[0], argv);
222: perror(argv[0]);
1.38 markus 223: exit(1);
224: }
225: /* Parent. */
226: if (pid < 0)
227: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 228: else
229: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 230:
231: /* Close child side of the descriptors. */
232: close(pin[0]);
233: close(pout[1]);
234:
235: /* Free the command name. */
1.238 djm 236: free(command_string);
1.38 markus 237:
238: /* Set the connection file descriptors. */
239: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 240:
1.110 markus 241: /* Indicate OK return */
242: return 0;
1.227 djm 243: }
244:
245: void
246: ssh_kill_proxy_command(void)
247: {
248: /*
249: * Send SIGHUP to proxy command if used. We don't wait() in
250: * case it hangs and instead rely on init to reap the child
251: */
252: if (proxy_command_pid > 1)
1.228 djm 253: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 254: }
255:
1.39 deraadt 256: /*
257: * Creates a (possibly privileged) socket for use as the ssh connection.
258: */
1.109 itojun 259: static int
1.139 markus 260: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 261: {
1.240 djm 262: int sock, r, gaierr;
1.246 djm 263: struct addrinfo hints, *res = NULL;
1.1 deraadt 264:
1.217 dtucker 265: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 266: if (sock < 0) {
1.240 djm 267: error("socket: %s", strerror(errno));
1.216 dtucker 268: return -1;
269: }
270: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 271:
272: /* Bind the socket to an alternative local IP address */
1.240 djm 273: if (options.bind_address == NULL && !privileged)
1.105 markus 274: return sock;
275:
1.246 djm 276: if (options.bind_address) {
277: memset(&hints, 0, sizeof(hints));
278: hints.ai_family = ai->ai_family;
279: hints.ai_socktype = ai->ai_socktype;
280: hints.ai_protocol = ai->ai_protocol;
281: hints.ai_flags = AI_PASSIVE;
282: gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
283: if (gaierr) {
284: error("getaddrinfo: %s: %s", options.bind_address,
285: ssh_gai_strerror(gaierr));
286: close(sock);
287: return -1;
288: }
1.105 markus 289: }
1.240 djm 290: /*
291: * If we are running as root and want to connect to a privileged
292: * port, bind our own socket to a privileged port.
293: */
294: if (privileged) {
295: PRIV_START;
1.246 djm 296: r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
1.240 djm 297: PRIV_END;
298: if (r < 0) {
299: error("bindresvport_sa: af=%d %s", ai->ai_family,
300: strerror(errno));
301: goto fail;
302: }
303: } else {
304: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
305: error("bind: %s: %s", options.bind_address,
306: strerror(errno));
307: fail:
308: close(sock);
309: freeaddrinfo(res);
310: return -1;
311: }
1.38 markus 312: }
1.246 djm 313: if (res != NULL)
314: freeaddrinfo(res);
1.38 markus 315: return sock;
1.1 deraadt 316: }
317:
1.141 djm 318: static int
319: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 320: socklen_t addrlen, int *timeoutp)
1.141 djm 321: {
322: fd_set *fdset;
1.202 djm 323: struct timeval tv, t_start;
1.141 djm 324: socklen_t optlen;
1.179 djm 325: int optval, rc, result = -1;
1.141 djm 326:
1.202 djm 327: gettimeofday(&t_start, NULL);
328:
329: if (*timeoutp <= 0) {
330: result = connect(sockfd, serv_addr, addrlen);
331: goto done;
332: }
1.141 djm 333:
1.156 djm 334: set_nonblock(sockfd);
1.141 djm 335: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 336: if (rc == 0) {
337: unset_nonblock(sockfd);
1.202 djm 338: result = 0;
339: goto done;
340: }
341: if (errno != EINPROGRESS) {
342: result = -1;
343: goto done;
1.156 djm 344: }
1.141 djm 345:
1.179 djm 346: fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
347: sizeof(fd_mask));
1.141 djm 348: FD_SET(sockfd, fdset);
1.202 djm 349: ms_to_timeval(&tv, *timeoutp);
1.141 djm 350:
1.162 deraadt 351: for (;;) {
1.141 djm 352: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
353: if (rc != -1 || errno != EINTR)
354: break;
355: }
356:
1.162 deraadt 357: switch (rc) {
1.141 djm 358: case 0:
359: /* Timed out */
360: errno = ETIMEDOUT;
1.142 djm 361: break;
1.141 djm 362: case -1:
363: /* Select error */
1.154 djm 364: debug("select: %s", strerror(errno));
1.142 djm 365: break;
1.141 djm 366: case 1:
367: /* Completed or failed */
368: optval = 0;
369: optlen = sizeof(optval);
1.154 djm 370: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 371: &optlen) == -1) {
1.154 djm 372: debug("getsockopt: %s", strerror(errno));
1.142 djm 373: break;
1.148 markus 374: }
1.141 djm 375: if (optval != 0) {
376: errno = optval;
1.142 djm 377: break;
1.141 djm 378: }
1.142 djm 379: result = 0;
1.156 djm 380: unset_nonblock(sockfd);
1.141 djm 381: break;
382: default:
383: /* Should not occur */
384: fatal("Bogus return (%d) from select()", rc);
385: }
386:
1.238 djm 387: free(fdset);
1.202 djm 388:
389: done:
390: if (result == 0 && *timeoutp > 0) {
391: ms_subtract_diff(&t_start, timeoutp);
392: if (*timeoutp <= 0) {
393: errno = ETIMEDOUT;
394: result = -1;
395: }
396: }
397:
1.142 djm 398: return (result);
1.141 djm 399: }
400:
1.39 deraadt 401: /*
1.49 markus 402: * Opens a TCP/IP connection to the remote server on the given host.
403: * The address of the remote host will be returned in hostaddr.
1.124 markus 404: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 405: * a privileged port will be allocated to make the connection.
1.124 markus 406: * This requires super-user privileges if needpriv is true.
1.39 deraadt 407: * Connection_attempts specifies the maximum number of tries (one per
408: * second). If proxy_command is non-NULL, it specifies the command (with %h
409: * and %p substituted for host and port, respectively) to use to contact
410: * the daemon.
411: */
1.241 djm 412: static int
413: ssh_connect_direct(const char *host, struct addrinfo *aitop,
414: struct sockaddr_storage *hostaddr, u_short port, int family,
415: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
1.1 deraadt 416: {
1.90 markus 417: int on = 1;
1.49 markus 418: int sock = -1, attempt;
1.90 markus 419: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 420: struct addrinfo *ai;
1.38 markus 421:
1.136 markus 422: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 423:
1.181 markus 424: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 425: if (attempt > 0) {
426: /* Sleep a moment before retrying. */
427: sleep(1);
1.38 markus 428: debug("Trying again...");
1.200 markus 429: }
1.181 markus 430: /*
431: * Loop through addresses for this host, and try each one in
432: * sequence until the connection succeeds.
433: */
1.49 markus 434: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 435: if (ai->ai_family != AF_INET &&
436: ai->ai_family != AF_INET6)
1.49 markus 437: continue;
438: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
439: ntop, sizeof(ntop), strport, sizeof(strport),
440: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
441: error("ssh_connect: getnameinfo failed");
442: continue;
443: }
444: debug("Connecting to %.200s [%.100s] port %s.",
445: host, ntop, strport);
446:
447: /* Create a socket for connecting. */
1.139 markus 448: sock = ssh_create_socket(needpriv, ai);
1.49 markus 449: if (sock < 0)
1.110 markus 450: /* Any error is already output */
1.49 markus 451: continue;
452:
1.141 djm 453: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 454: timeout_ms) >= 0) {
1.49 markus 455: /* Successful connection. */
1.102 markus 456: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 457: break;
1.49 markus 458: } else {
1.131 itojun 459: debug("connect to address %s port %s: %s",
460: ntop, strport, strerror(errno));
1.38 markus 461: close(sock);
1.181 markus 462: sock = -1;
1.38 markus 463: }
464: }
1.181 markus 465: if (sock != -1)
1.49 markus 466: break; /* Successful connection. */
1.38 markus 467: }
1.49 markus 468:
1.38 markus 469: /* Return failure if we didn't get a successful connection. */
1.181 markus 470: if (sock == -1) {
1.159 markus 471: error("ssh: connect to host %s port %s: %s",
1.130 itojun 472: host, strport, strerror(errno));
1.159 markus 473: return (-1);
1.130 itojun 474: }
1.38 markus 475:
476: debug("Connection established.");
1.90 markus 477:
1.155 markus 478: /* Set SO_KEEPALIVE if requested. */
1.202 djm 479: if (want_keepalive &&
1.90 markus 480: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
481: sizeof(on)) < 0)
482: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 483:
484: /* Set the connection. */
485: packet_set_connection(sock, sock);
1.1 deraadt 486:
1.110 markus 487: return 0;
1.59 markus 488: }
489:
1.241 djm 490: int
491: ssh_connect(const char *host, struct addrinfo *addrs,
492: struct sockaddr_storage *hostaddr, u_short port, int family,
493: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
494: {
495: if (options.proxy_command == NULL) {
496: return ssh_connect_direct(host, addrs, hostaddr, port, family,
497: connection_attempts, timeout_ms, want_keepalive, needpriv);
498: } else if (strcmp(options.proxy_command, "-") == 0) {
499: packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
500: return 0; /* Always succeeds */
501: } else if (options.proxy_use_fdpass) {
502: return ssh_proxy_fdpass_connect(host, port,
503: options.proxy_command);
504: }
505: return ssh_proxy_connect(host, port, options.proxy_command);
506: }
507:
1.235 djm 508: static void
509: send_client_banner(int connection_out, int minor1)
510: {
511: /* Send our own protocol version identification. */
512: if (compat20) {
513: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
514: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
515: } else {
516: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n",
517: PROTOCOL_MAJOR_1, minor1, SSH_VERSION);
518: }
519: if (roaming_atomicio(vwrite, connection_out, client_version_string,
520: strlen(client_version_string)) != strlen(client_version_string))
521: fatal("write: %.100s", strerror(errno));
522: chop(client_version_string);
523: debug("Local version string %.100s", client_version_string);
524: }
525:
1.43 markus 526: /*
1.39 deraadt 527: * Waits for the server identification string, and sends our own
528: * identification string.
529: */
1.213 andreas 530: void
1.202 djm 531: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 532: {
1.38 markus 533: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 534: int remote_major, remote_minor, mismatch;
1.38 markus 535: int connection_in = packet_get_connection_in();
536: int connection_out = packet_get_connection_out();
1.235 djm 537: int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
1.185 djm 538: u_int i, n;
1.202 djm 539: size_t len;
540: int fdsetsz, remaining, rc;
541: struct timeval t_start, t_remaining;
542: fd_set *fdset;
543:
544: fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
545: fdset = xcalloc(1, fdsetsz);
1.38 markus 546:
1.235 djm 547: /*
548: * If we are SSH2-only then we can send the banner immediately and
549: * save a round-trip.
550: */
551: if (options.protocol == SSH_PROTO_2) {
552: enable_compat20();
553: send_client_banner(connection_out, 0);
554: client_banner_sent = 1;
555: }
556:
1.163 avsm 557: /* Read other side's version identification. */
1.202 djm 558: remaining = timeout_ms;
1.185 djm 559: for (n = 0;;) {
1.75 markus 560: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 561: if (timeout_ms > 0) {
562: gettimeofday(&t_start, NULL);
563: ms_to_timeval(&t_remaining, remaining);
564: FD_SET(connection_in, fdset);
565: rc = select(connection_in + 1, fdset, NULL,
566: fdset, &t_remaining);
567: ms_subtract_diff(&t_start, &remaining);
568: if (rc == 0 || remaining <= 0)
569: fatal("Connection timed out during "
570: "banner exchange");
571: if (rc == -1) {
572: if (errno == EINTR)
573: continue;
574: fatal("ssh_exchange_identification: "
575: "select: %s", strerror(errno));
576: }
577: }
578:
1.214 andreas 579: len = roaming_atomicio(read, connection_in, &buf[i], 1);
1.163 avsm 580:
1.167 djm 581: if (len != 1 && errno == EPIPE)
1.202 djm 582: fatal("ssh_exchange_identification: "
583: "Connection closed by remote host");
1.163 avsm 584: else if (len != 1)
1.202 djm 585: fatal("ssh_exchange_identification: "
586: "read: %.100s", strerror(errno));
1.75 markus 587: if (buf[i] == '\r') {
588: buf[i] = '\n';
589: buf[i + 1] = 0;
590: continue; /**XXX wait for \n */
591: }
592: if (buf[i] == '\n') {
593: buf[i + 1] = 0;
594: break;
595: }
1.185 djm 596: if (++n > 65536)
1.202 djm 597: fatal("ssh_exchange_identification: "
598: "No banner received");
1.38 markus 599: }
1.75 markus 600: buf[sizeof(buf) - 1] = 0;
1.76 markus 601: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 602: break;
1.75 markus 603: debug("ssh_exchange_identification: %s", buf);
1.38 markus 604: }
1.59 markus 605: server_version_string = xstrdup(buf);
1.238 djm 606: free(fdset);
1.38 markus 607:
1.40 markus 608: /*
609: * Check that the versions match. In future this might accept
610: * several versions and set appropriate flags to handle them.
611: */
1.59 markus 612: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
613: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 614: fatal("Bad remote protocol version identification: '%.100s'", buf);
615: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 616: remote_major, remote_minor, remote_version);
1.38 markus 617:
1.59 markus 618: compat_datafellows(remote_version);
1.64 markus 619: mismatch = 0;
1.59 markus 620:
1.116 deraadt 621: switch (remote_major) {
1.64 markus 622: case 1:
623: if (remote_minor == 99 &&
624: (options.protocol & SSH_PROTO_2) &&
625: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
626: enable_compat20();
627: break;
628: }
629: if (!(options.protocol & SSH_PROTO_1)) {
630: mismatch = 1;
631: break;
632: }
633: if (remote_minor < 3) {
634: fatal("Remote machine has too old SSH software version.");
1.81 markus 635: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 636: /* We speak 1.3, too. */
637: enable_compat13();
1.81 markus 638: minor1 = 3;
1.64 markus 639: if (options.forward_agent) {
1.138 itojun 640: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 641: options.forward_agent = 0;
642: }
643: }
644: break;
645: case 2:
646: if (options.protocol & SSH_PROTO_2) {
647: enable_compat20();
648: break;
1.38 markus 649: }
1.64 markus 650: /* FALLTHROUGH */
1.68 markus 651: default:
1.64 markus 652: mismatch = 1;
653: break;
1.38 markus 654: }
1.64 markus 655: if (mismatch)
1.38 markus 656: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 657: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
658: remote_major);
1.244 djm 659: if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
660: fatal("Server version \"%.100s\" uses unsafe key agreement; "
661: "refusing connection", remote_version);
1.243 djm 662: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
663: logit("Server version \"%.100s\" uses unsafe RSA signature "
664: "scheme; disabling use of RSA keys", remote_version);
1.235 djm 665: if (!client_banner_sent)
666: send_client_banner(connection_out, minor1);
1.59 markus 667: chop(server_version_string);
1.1 deraadt 668: }
669:
1.96 markus 670: /* defaults to 'no' */
1.109 itojun 671: static int
1.112 markus 672: confirm(const char *prompt)
1.1 deraadt 673: {
1.119 markus 674: const char *msg, *again = "Please type 'yes' or 'no': ";
675: char *p;
676: int ret = -1;
1.96 markus 677:
678: if (options.batch_mode)
679: return 0;
1.119 markus 680: for (msg = prompt;;msg = again) {
681: p = read_passphrase(msg, RP_ECHO);
682: if (p == NULL ||
683: (p[0] == '\0') || (p[0] == '\n') ||
684: strncasecmp(p, "no", 2) == 0)
685: ret = 0;
1.127 markus 686: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 687: ret = 1;
1.238 djm 688: free(p);
1.119 markus 689: if (ret != -1)
690: return ret;
1.1 deraadt 691: }
692: }
693:
1.219 djm 694: static int
695: check_host_cert(const char *host, const Key *host_key)
696: {
697: const char *reason;
698:
699: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
700: error("%s", reason);
701: return 0;
702: }
1.249 djm 703: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 704: error("Certificate for %s contains unsupported "
705: "critical options(s)", host);
1.219 djm 706: return 0;
707: }
708: return 1;
709: }
710:
1.229 djm 711: static int
712: sockaddr_is_local(struct sockaddr *hostaddr)
713: {
714: switch (hostaddr->sa_family) {
715: case AF_INET:
716: return (ntohl(((struct sockaddr_in *)hostaddr)->
717: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
718: case AF_INET6:
719: return IN6_IS_ADDR_LOOPBACK(
720: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
721: default:
722: return 0;
723: }
724: }
725:
726: /*
727: * Prepare the hostname and ip address strings that are used to lookup
728: * host keys in known_hosts files. These may have a port number appended.
729: */
730: void
731: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
732: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
733: {
734: char ntop[NI_MAXHOST];
735:
736: /*
737: * We don't have the remote ip-address for connections
738: * using a proxy command
739: */
740: if (hostfile_ipaddr != NULL) {
741: if (options.proxy_command == NULL) {
742: if (getnameinfo(hostaddr, hostaddr->sa_len,
743: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
744: fatal("check_host_key: getnameinfo failed");
745: *hostfile_ipaddr = put_host_port(ntop, port);
746: } else {
747: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
748: "command>");
749: }
750: }
751:
752: /*
753: * Allow the user to record the key under a different name or
754: * differentiate a non-standard port. This is useful for ssh
755: * tunneling over forwarded connections or if you run multiple
756: * sshd's on different ports on the same machine.
757: */
758: if (hostfile_hostname != NULL) {
759: if (options.host_key_alias != NULL) {
760: *hostfile_hostname = xstrdup(options.host_key_alias);
761: debug("using hostkeyalias: %s", *hostfile_hostname);
762: } else {
763: *hostfile_hostname = put_host_port(hostname, port);
764: }
765: }
766: }
767:
1.39 deraadt 768: /*
1.108 markus 769: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 770: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 771: */
1.197 dtucker 772: #define RDRW 0
773: #define RDONLY 1
774: #define ROQUIET 2
1.109 itojun 775: static int
1.197 dtucker 776: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.234 djm 777: Key *host_key, int readonly,
778: char **user_hostfiles, u_int num_user_hostfiles,
779: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 780: {
1.234 djm 781: HostStatus host_status;
782: HostStatus ip_status;
1.229 djm 783: Key *raw_key = NULL;
1.189 dtucker 784: char *ip = NULL, *host = NULL;
1.204 grunk 785: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 786: char msg[1024];
1.234 djm 787: const char *type;
788: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 789: int len, cancelled_forwarding = 0;
1.234 djm 790: int local = sockaddr_is_local(hostaddr);
791: int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
1.229 djm 792: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 793: u_int i;
1.49 markus 794:
795: /*
796: * Force accepting of the host key for loopback/localhost. The
797: * problem is that if the home directory is NFS-mounted to multiple
798: * machines, localhost will refer to a different machine in each of
799: * them, and the user will get bogus HOST_CHANGED warnings. This
800: * essentially disables host authentication for localhost; however,
801: * this is probably not a real problem.
802: */
1.111 markus 803: if (options.no_host_authentication_for_localhost == 1 && local &&
804: options.host_key_alias == NULL) {
1.88 markus 805: debug("Forcing accepting of host key for "
806: "loopback/localhost.");
1.108 markus 807: return 0;
1.49 markus 808: }
1.42 markus 809:
810: /*
1.229 djm 811: * Prepare the hostname and address strings used for hostkey lookup.
812: * In some cases, these will have a port number appended.
1.42 markus 813: */
1.229 djm 814: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 815:
816: /*
1.88 markus 817: * Turn off check_host_ip if the connection is to localhost, via proxy
818: * command or if we don't have a hostname to compare with
819: */
1.189 dtucker 820: if (options.check_host_ip && (local ||
821: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 822: options.check_host_ip = 0;
1.86 markus 823:
1.229 djm 824: host_hostkeys = init_hostkeys();
1.234 djm 825: for (i = 0; i < num_user_hostfiles; i++)
826: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
827: for (i = 0; i < num_system_hostfiles; i++)
828: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 829:
830: ip_hostkeys = NULL;
831: if (!want_cert && options.check_host_ip) {
832: ip_hostkeys = init_hostkeys();
1.234 djm 833: for (i = 0; i < num_user_hostfiles; i++)
834: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
835: for (i = 0; i < num_system_hostfiles; i++)
836: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 837: }
1.38 markus 838:
1.219 djm 839: retry:
1.229 djm 840: /* Reload these as they may have changed on cert->key downgrade */
1.219 djm 841: want_cert = key_is_cert(host_key);
842: type = key_type(host_key);
843:
1.46 markus 844: /*
1.170 djm 845: * Check if the host key is present in the user's list of known
1.40 markus 846: * hosts or in the systemwide list.
847: */
1.229 djm 848: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
849: &host_found);
850:
1.40 markus 851: /*
852: * Also perform check for the ip address, skip the check if we are
1.219 djm 853: * localhost, looking for a certificate, or the hostname was an ip
854: * address to begin with.
1.40 markus 855: */
1.229 djm 856: if (!want_cert && ip_hostkeys != NULL) {
857: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
858: &ip_found);
1.38 markus 859: if (host_status == HOST_CHANGED &&
1.229 djm 860: (ip_status != HOST_CHANGED ||
861: (ip_found != NULL &&
862: !key_equal(ip_found->key, host_found->key))))
1.38 markus 863: host_ip_differ = 1;
864: } else
865: ip_status = host_status;
866:
867: switch (host_status) {
868: case HOST_OK:
869: /* The host is known and the key matches. */
1.219 djm 870: debug("Host '%.200s' is known and matches the %s host %s.",
871: host, type, want_cert ? "certificate" : "key");
1.229 djm 872: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
873: host_found->file, host_found->line);
1.219 djm 874: if (want_cert && !check_host_cert(hostname, host_key))
875: goto fail;
1.88 markus 876: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 877: if (readonly || want_cert)
1.138 itojun 878: logit("%s host key for IP address "
1.108 markus 879: "'%.128s' not in list of known hosts.",
880: type, ip);
1.234 djm 881: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 882: host_key, options.hash_known_hosts))
1.138 itojun 883: logit("Failed to add the %s host key for IP "
1.108 markus 884: "address '%.128s' to the list of known "
1.234 djm 885: "hosts (%.30s).", type, ip,
886: user_hostfiles[0]);
1.88 markus 887: else
1.138 itojun 888: logit("Warning: Permanently added the %s host "
1.108 markus 889: "key for IP address '%.128s' to the list "
890: "of known hosts.", type, ip);
1.209 grunk 891: } else if (options.visual_host_key) {
1.204 grunk 892: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
893: ra = key_fingerprint(host_key, SSH_FP_MD5,
894: SSH_FP_RANDOMART);
895: logit("Host key fingerprint is %s\n%s\n", fp, ra);
1.238 djm 896: free(ra);
897: free(fp);
1.38 markus 898: }
899: break;
900: case HOST_NEW:
1.197 dtucker 901: if (options.host_key_alias == NULL && port != 0 &&
902: port != SSH_DEFAULT_PORT) {
903: debug("checking without port identifier");
1.212 stevesk 904: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 905: ROQUIET, user_hostfiles, num_user_hostfiles,
906: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 907: debug("found matching key w/out port");
908: break;
909: }
910: }
1.219 djm 911: if (readonly || want_cert)
1.108 markus 912: goto fail;
1.38 markus 913: /* The host is new. */
914: if (options.strict_host_key_checking == 1) {
1.108 markus 915: /*
916: * User has requested strict host key checking. We
917: * will not add the host key automatically. The only
918: * alternative left is to abort.
919: */
920: error("No %s host key is known for %.200s and you "
921: "have requested strict checking.", type, host);
922: goto fail;
1.38 markus 923: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 924: char msg1[1024], msg2[1024];
925:
1.229 djm 926: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 927: snprintf(msg1, sizeof(msg1),
1.168 djm 928: "\nbut keys of different type are already"
929: " known for this host.");
1.145 jakob 930: else
931: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 932: /* The default */
1.100 markus 933: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.204 grunk 934: ra = key_fingerprint(host_key, SSH_FP_MD5,
935: SSH_FP_RANDOMART);
1.145 jakob 936: msg2[0] = '\0';
937: if (options.verify_host_key_dns) {
1.153 jakob 938: if (matching_host_key_dns)
1.145 jakob 939: snprintf(msg2, sizeof(msg2),
940: "Matching host key fingerprint"
941: " found in DNS.\n");
942: else
943: snprintf(msg2, sizeof(msg2),
944: "No matching host key fingerprint"
945: " found in DNS.\n");
946: }
1.119 markus 947: snprintf(msg, sizeof(msg),
1.108 markus 948: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 949: "established%s\n"
1.209 grunk 950: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 951: "Are you sure you want to continue connecting "
1.132 markus 952: "(yes/no)? ",
1.209 grunk 953: host, ip, msg1, type, fp,
954: options.visual_host_key ? "\n" : "",
955: options.visual_host_key ? ra : "",
956: msg2);
1.238 djm 957: free(ra);
958: free(fp);
1.119 markus 959: if (!confirm(msg))
1.108 markus 960: goto fail;
1.38 markus 961: }
1.161 djm 962: /*
963: * If not in strict mode, add the key automatically to the
964: * local known_hosts file.
965: */
1.88 markus 966: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 967: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 968: hostp = hostline;
1.161 djm 969: if (options.hash_known_hosts) {
970: /* Add hash of host and IP separately */
1.234 djm 971: r = add_host_to_hostfile(user_hostfiles[0],
972: host, host_key, options.hash_known_hosts) &&
973: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 974: host_key, options.hash_known_hosts);
975: } else {
976: /* Add unhashed "host,ip" */
1.234 djm 977: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 978: hostline, host_key,
979: options.hash_known_hosts);
980: }
981: } else {
1.234 djm 982: r = add_host_to_hostfile(user_hostfiles[0], host,
983: host_key, options.hash_known_hosts);
1.38 markus 984: hostp = host;
1.161 djm 985: }
1.38 markus 986:
1.161 djm 987: if (!r)
1.138 itojun 988: logit("Failed to add the host to the list of known "
1.234 djm 989: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 990: else
1.138 itojun 991: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 992: "list of known hosts.", hostp, type);
1.38 markus 993: break;
1.220 djm 994: case HOST_REVOKED:
995: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
996: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
997: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
998: error("The %s host key for %s is marked as revoked.", type, host);
999: error("This could mean that a stolen key is being used to");
1000: error("impersonate this host.");
1001:
1002: /*
1003: * If strict host key checking is in use, the user will have
1004: * to edit the key manually and we can only abort.
1005: */
1006: if (options.strict_host_key_checking) {
1007: error("%s host key for %.200s was revoked and you have "
1008: "requested strict checking.", type, host);
1009: goto fail;
1010: }
1011: goto continue_unsafe;
1012:
1.38 markus 1013: case HOST_CHANGED:
1.219 djm 1014: if (want_cert) {
1015: /*
1016: * This is only a debug() since it is valid to have
1017: * CAs with wildcard DNS matches that don't match
1018: * all hosts that one might visit.
1019: */
1020: debug("Host certificate authority does not "
1.229 djm 1021: "match %s in %s:%lu", CA_MARKER,
1022: host_found->file, host_found->line);
1.219 djm 1023: goto fail;
1024: }
1.197 dtucker 1025: if (readonly == ROQUIET)
1026: goto fail;
1.38 markus 1027: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1028: char *key_msg;
1.38 markus 1029: if (ip_status == HOST_NEW)
1.158 avsm 1030: key_msg = "is unknown";
1.38 markus 1031: else if (ip_status == HOST_OK)
1.158 avsm 1032: key_msg = "is unchanged";
1.38 markus 1033: else
1.158 avsm 1034: key_msg = "has a different value";
1.38 markus 1035: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1036: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1037: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1038: error("The %s host key for %s has changed,", type, host);
1.208 ian 1039: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1040: error("%s. This could either mean that", key_msg);
1.38 markus 1041: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1042: error("and its host key have changed at the same time.");
1.88 markus 1043: if (ip_status != HOST_NEW)
1.229 djm 1044: error("Offending key for IP in %s:%lu",
1045: ip_found->file, ip_found->line);
1.38 markus 1046: }
1047: /* The host key has changed. */
1.150 jakob 1048: warn_changed_key(host_key);
1.38 markus 1049: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1050: user_hostfiles[0]);
1.229 djm 1051: error("Offending %s key in %s:%lu", key_type(host_found->key),
1052: host_found->file, host_found->line);
1.38 markus 1053:
1.40 markus 1054: /*
1055: * If strict host key checking is in use, the user will have
1056: * to edit the key manually and we can only abort.
1057: */
1.108 markus 1058: if (options.strict_host_key_checking) {
1059: error("%s host key for %.200s has changed and you have "
1060: "requested strict checking.", type, host);
1061: goto fail;
1062: }
1.38 markus 1063:
1.220 djm 1064: continue_unsafe:
1.40 markus 1065: /*
1066: * If strict host key checking has not been requested, allow
1.144 djm 1067: * the connection but without MITM-able authentication or
1.194 stevesk 1068: * forwarding.
1.40 markus 1069: */
1.38 markus 1070: if (options.password_authentication) {
1.108 markus 1071: error("Password authentication is disabled to avoid "
1072: "man-in-the-middle attacks.");
1.38 markus 1073: options.password_authentication = 0;
1.210 dtucker 1074: cancelled_forwarding = 1;
1.144 djm 1075: }
1076: if (options.kbd_interactive_authentication) {
1077: error("Keyboard-interactive authentication is disabled"
1078: " to avoid man-in-the-middle attacks.");
1079: options.kbd_interactive_authentication = 0;
1080: options.challenge_response_authentication = 0;
1.210 dtucker 1081: cancelled_forwarding = 1;
1.144 djm 1082: }
1083: if (options.challenge_response_authentication) {
1084: error("Challenge/response authentication is disabled"
1085: " to avoid man-in-the-middle attacks.");
1086: options.challenge_response_authentication = 0;
1.210 dtucker 1087: cancelled_forwarding = 1;
1.38 markus 1088: }
1089: if (options.forward_agent) {
1.108 markus 1090: error("Agent forwarding is disabled to avoid "
1091: "man-in-the-middle attacks.");
1.38 markus 1092: options.forward_agent = 0;
1.210 dtucker 1093: cancelled_forwarding = 1;
1.83 markus 1094: }
1095: if (options.forward_x11) {
1.108 markus 1096: error("X11 forwarding is disabled to avoid "
1097: "man-in-the-middle attacks.");
1.83 markus 1098: options.forward_x11 = 0;
1.210 dtucker 1099: cancelled_forwarding = 1;
1.83 markus 1100: }
1.108 markus 1101: if (options.num_local_forwards > 0 ||
1102: options.num_remote_forwards > 0) {
1103: error("Port forwarding is disabled to avoid "
1104: "man-in-the-middle attacks.");
1105: options.num_local_forwards =
1.118 deraadt 1106: options.num_remote_forwards = 0;
1.210 dtucker 1107: cancelled_forwarding = 1;
1.194 stevesk 1108: }
1109: if (options.tun_open != SSH_TUNMODE_NO) {
1110: error("Tunnel forwarding is disabled to avoid "
1111: "man-in-the-middle attacks.");
1112: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1113: cancelled_forwarding = 1;
1.38 markus 1114: }
1.210 dtucker 1115: if (options.exit_on_forward_failure && cancelled_forwarding)
1116: fatal("Error: forwarding disabled due to host key "
1117: "check failure");
1118:
1.40 markus 1119: /*
1120: * XXX Should permit the user to change to use the new id.
1121: * This could be done by converting the host key to an
1122: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1123: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1124: * accept the authentication.
1125: */
1.38 markus 1126: break;
1.132 markus 1127: case HOST_FOUND:
1128: fatal("internal error");
1129: break;
1.88 markus 1130: }
1131:
1132: if (options.check_host_ip && host_status != HOST_CHANGED &&
1133: ip_status == HOST_CHANGED) {
1.119 markus 1134: snprintf(msg, sizeof(msg),
1135: "Warning: the %s host key for '%.200s' "
1136: "differs from the key for the IP address '%.128s'"
1.229 djm 1137: "\nOffending key for IP in %s:%lu",
1138: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1139: if (host_status == HOST_OK) {
1140: len = strlen(msg);
1141: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1142: "\nMatching host key in %s:%lu",
1143: host_found->file, host_found->line);
1.119 markus 1144: }
1.88 markus 1145: if (options.strict_host_key_checking == 1) {
1.143 djm 1146: logit("%s", msg);
1.108 markus 1147: error("Exiting, you have requested strict checking.");
1148: goto fail;
1.88 markus 1149: } else if (options.strict_host_key_checking == 2) {
1.119 markus 1150: strlcat(msg, "\nAre you sure you want "
1151: "to continue connecting (yes/no)? ", sizeof(msg));
1152: if (!confirm(msg))
1.108 markus 1153: goto fail;
1.119 markus 1154: } else {
1.143 djm 1155: logit("%s", msg);
1.88 markus 1156: }
1.38 markus 1157: }
1.82 provos 1158:
1.238 djm 1159: free(ip);
1160: free(host);
1.229 djm 1161: if (host_hostkeys != NULL)
1162: free_hostkeys(host_hostkeys);
1163: if (ip_hostkeys != NULL)
1164: free_hostkeys(ip_hostkeys);
1.108 markus 1165: return 0;
1166:
1167: fail:
1.220 djm 1168: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1169: /*
1170: * No matching certificate. Downgrade cert to raw key and
1171: * search normally.
1172: */
1173: debug("No matching CA found. Retry with plain key");
1174: raw_key = key_from_private(host_key);
1175: if (key_drop_cert(raw_key) != 0)
1176: fatal("Couldn't drop certificate");
1177: host_key = raw_key;
1178: goto retry;
1179: }
1180: if (raw_key != NULL)
1181: key_free(raw_key);
1.238 djm 1182: free(ip);
1183: free(host);
1.229 djm 1184: if (host_hostkeys != NULL)
1185: free_hostkeys(host_hostkeys);
1186: if (ip_hostkeys != NULL)
1187: free_hostkeys(ip_hostkeys);
1.108 markus 1188: return -1;
1189: }
1190:
1.140 jakob 1191: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1192: int
1193: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1194: {
1.250 djm 1195: int r = -1, flags = 0;
1.229 djm 1196: char *fp;
1.247 djm 1197: Key *plain = NULL;
1.229 djm 1198:
1199: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1200: debug("Server host key: %s %s", key_type(host_key), fp);
1.238 djm 1201: free(fp);
1.140 jakob 1202:
1.250 djm 1203: if (key_equal(previous_host_key, host_key)) {
1204: debug("%s: server host key matches cached key", __func__);
1205: return 0;
1206: }
1207:
1.247 djm 1208: if (options.verify_host_key_dns) {
1209: /*
1210: * XXX certs are not yet supported for DNS, so downgrade
1211: * them and try the plain key.
1212: */
1213: plain = key_from_private(host_key);
1214: if (key_is_cert(plain))
1215: key_drop_cert(plain);
1216: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1217: if (flags & DNS_VERIFY_FOUND) {
1218: if (options.verify_host_key_dns == 1 &&
1219: flags & DNS_VERIFY_MATCH &&
1220: flags & DNS_VERIFY_SECURE) {
1221: key_free(plain);
1.250 djm 1222: r = 0;
1223: goto done;
1.247 djm 1224: }
1225: if (flags & DNS_VERIFY_MATCH) {
1226: matching_host_key_dns = 1;
1227: } else {
1228: warn_changed_key(plain);
1229: error("Update the SSHFP RR in DNS "
1230: "with the new host key to get rid "
1231: "of this message.");
1232: }
1.153 jakob 1233: }
1.140 jakob 1234: }
1.247 djm 1235: key_free(plain);
1.140 jakob 1236: }
1.108 markus 1237:
1.250 djm 1238: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1239: options.user_hostfiles, options.num_user_hostfiles,
1240: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1241:
1242: done:
1243: if (r == 0 && host_key != NULL) {
1244: key_free(previous_host_key);
1245: previous_host_key = key_from_private(host_key);
1246: }
1247:
1248: return r;
1.51 markus 1249: }
1.70 markus 1250:
1.51 markus 1251: /*
1252: * Starts a dialog with the server, and authenticates the current user on the
1253: * server. This does not need any extra privileges. The basic connection
1254: * to the server must already have been established before this is called.
1255: * If login fails, this function prints an error and never returns.
1256: * This function does not require super-user privileges.
1257: */
1258: void
1.120 markus 1259: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1260: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1261: {
1.241 djm 1262: char *host;
1.70 markus 1263: char *server_user, *local_user;
1264:
1265: local_user = xstrdup(pw->pw_name);
1266: server_user = options.user ? options.user : local_user;
1.51 markus 1267:
1268: /* Convert the user-supplied hostname into all lowercase. */
1269: host = xstrdup(orighost);
1.241 djm 1270: lowercase(host);
1.51 markus 1271:
1272: /* Exchange protocol version identification strings with the server. */
1.202 djm 1273: ssh_exchange_identification(timeout_ms);
1.51 markus 1274:
1275: /* Put the connection into non-blocking mode. */
1276: packet_set_nonblocking();
1277:
1278: /* key exchange */
1279: /* authenticate user */
1.59 markus 1280: if (compat20) {
1.229 djm 1281: ssh_kex2(host, hostaddr, port);
1.120 markus 1282: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 1283: } else {
1.248 markus 1284: #ifdef WITH_SSH1
1.59 markus 1285: ssh_kex(host, hostaddr);
1.120 markus 1286: ssh_userauth1(local_user, server_user, host, sensitive);
1.248 markus 1287: #else
1288: fatal("ssh1 is not unsupported");
1289: #endif
1.59 markus 1290: }
1.238 djm 1291: free(local_user);
1.97 markus 1292: }
1293:
1294: void
1295: ssh_put_password(char *password)
1296: {
1297: int size;
1298: char *padded;
1299:
1.99 deraadt 1300: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1301: packet_put_cstring(password);
1.99 deraadt 1302: return;
1303: }
1.97 markus 1304: size = roundup(strlen(password) + 1, 32);
1.179 djm 1305: padded = xcalloc(1, size);
1.97 markus 1306: strlcpy(padded, password, size);
1307: packet_put_string(padded, size);
1.245 djm 1308: explicit_bzero(padded, size);
1.238 djm 1309: free(padded);
1.132 markus 1310: }
1311:
1312: /* print all known host keys for a given host, but skip keys of given type */
1313: static int
1.229 djm 1314: show_other_keys(struct hostkeys *hostkeys, Key *key)
1.132 markus 1315: {
1.242 djm 1316: int type[] = {
1317: KEY_RSA1,
1318: KEY_RSA,
1319: KEY_DSA,
1320: KEY_ECDSA,
1321: KEY_ED25519,
1322: -1
1323: };
1.229 djm 1324: int i, ret = 0;
1325: char *fp, *ra;
1326: const struct hostkey_entry *found;
1.132 markus 1327:
1328: for (i = 0; type[i] != -1; i++) {
1329: if (type[i] == key->type)
1330: continue;
1.229 djm 1331: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1332: continue;
1.229 djm 1333: fp = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_HEX);
1334: ra = key_fingerprint(found->key, SSH_FP_MD5, SSH_FP_RANDOMART);
1335: logit("WARNING: %s key found for host %s\n"
1336: "in %s:%lu\n"
1337: "%s key fingerprint %s.",
1338: key_type(found->key),
1339: found->host, found->file, found->line,
1340: key_type(found->key), fp);
1341: if (options.visual_host_key)
1342: logit("%s", ra);
1.238 djm 1343: free(ra);
1344: free(fp);
1.229 djm 1345: ret = 1;
1.132 markus 1346: }
1.229 djm 1347: return ret;
1.150 jakob 1348: }
1349:
1350: static void
1351: warn_changed_key(Key *host_key)
1352: {
1353: char *fp;
1354:
1355: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1356:
1357: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1358: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1359: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1360: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1361: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1362: error("It is also possible that a host key has just been changed.");
1.150 jakob 1363: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.230 markus 1364: key_type(host_key), fp);
1.150 jakob 1365: error("Please contact your system administrator.");
1366:
1.238 djm 1367: free(fp);
1.171 reyk 1368: }
1369:
1370: /*
1371: * Execute a local command
1372: */
1373: int
1374: ssh_local_cmd(const char *args)
1375: {
1376: char *shell;
1377: pid_t pid;
1378: int status;
1.231 djm 1379: void (*osighand)(int);
1.171 reyk 1380:
1381: if (!options.permit_local_command ||
1382: args == NULL || !*args)
1383: return (1);
1384:
1.226 djm 1385: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1386: shell = _PATH_BSHELL;
1387:
1.231 djm 1388: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1389: pid = fork();
1390: if (pid == 0) {
1.232 djm 1391: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1392: debug3("Executing %s -c \"%s\"", shell, args);
1393: execl(shell, shell, "-c", args, (char *)NULL);
1394: error("Couldn't execute %s -c \"%s\": %s",
1395: shell, args, strerror(errno));
1396: _exit(1);
1397: } else if (pid == -1)
1398: fatal("fork failed: %.100s", strerror(errno));
1399: while (waitpid(pid, &status, 0) == -1)
1400: if (errno != EINTR)
1401: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1402: signal(SIGCHLD, osighand);
1.171 reyk 1403:
1404: if (!WIFEXITED(status))
1405: return (1);
1406:
1407: return (WEXITSTATUS(status));
1.1 deraadt 1408: }