Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.274
1.274 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.273 2017/03/10 03:22:40 dtucker 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"
1.239 djm 51: #include "monitor_fdpass.h"
1.219 djm 52: #include "ssh2.h"
1.186 stevesk 53: #include "version.h"
1.252 djm 54: #include "authfile.h"
55: #include "ssherr.h"
1.266 jcs 56: #include "authfd.h"
1.140 jakob 57:
1.70 markus 58: char *client_version_string = NULL;
59: char *server_version_string = NULL;
1.250 djm 60: Key *previous_host_key = NULL;
1.59 markus 61:
1.169 stevesk 62: static int matching_host_key_dns = 0;
1.145 jakob 63:
1.227 djm 64: static pid_t proxy_command_pid = 0;
65:
1.124 markus 66: /* import */
1.43 markus 67: extern Options options;
1.50 markus 68: extern char *__progname;
1.124 markus 69: extern uid_t original_real_uid;
70: extern uid_t original_effective_uid;
1.91 markus 71:
1.229 djm 72: static int show_other_keys(struct hostkeys *, Key *);
1.150 jakob 73: static void warn_changed_key(Key *);
1.132 markus 74:
1.239 djm 75: /* Expand a proxy command */
76: static char *
77: expand_proxy_command(const char *proxy_command, const char *user,
78: const char *host, int port)
79: {
80: char *tmp, *ret, strport[NI_MAXSERV];
81:
1.241 djm 82: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 83: xasprintf(&tmp, "exec %s", proxy_command);
84: ret = percent_expand(tmp, "h", host, "p", strport,
85: "r", options.user, (char *)NULL);
86: free(tmp);
87: return ret;
88: }
89:
90: /*
91: * Connect to the given ssh server using a proxy command that passes a
92: * a connected fd back to us.
93: */
94: static int
95: ssh_proxy_fdpass_connect(const char *host, u_short port,
96: const char *proxy_command)
97: {
98: char *command_string;
99: int sp[2], sock;
100: pid_t pid;
101: char *shell;
102:
103: if ((shell = getenv("SHELL")) == NULL)
104: shell = _PATH_BSHELL;
105:
106: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
107: fatal("Could not create socketpair to communicate with "
108: "proxy dialer: %.100s", strerror(errno));
109:
110: command_string = expand_proxy_command(proxy_command, options.user,
111: host, port);
112: debug("Executing proxy dialer command: %.500s", command_string);
113:
114: /* Fork and execute the proxy command. */
115: if ((pid = fork()) == 0) {
116: char *argv[10];
117:
118: /* Child. Permanently give up superuser privileges. */
119: permanently_drop_suid(original_real_uid);
120:
121: close(sp[1]);
122: /* Redirect stdin and stdout. */
123: if (sp[0] != 0) {
124: if (dup2(sp[0], 0) < 0)
125: perror("dup2 stdin");
126: }
127: if (sp[0] != 1) {
128: if (dup2(sp[0], 1) < 0)
129: perror("dup2 stdout");
130: }
131: if (sp[0] >= 2)
132: close(sp[0]);
133:
134: /*
135: * Stderr is left as it is so that error messages get
136: * printed on the user's terminal.
137: */
138: argv[0] = shell;
139: argv[1] = "-c";
140: argv[2] = command_string;
141: argv[3] = NULL;
142:
143: /*
144: * Execute the proxy command.
145: * Note that we gave up any extra privileges above.
146: */
147: execv(argv[0], argv);
148: perror(argv[0]);
149: exit(1);
150: }
151: /* Parent. */
152: if (pid < 0)
153: fatal("fork failed: %.100s", strerror(errno));
154: close(sp[0]);
155: free(command_string);
156:
157: if ((sock = mm_receive_fd(sp[1])) == -1)
158: fatal("proxy dialer did not pass back a connection");
1.271 markus 159: close(sp[1]);
1.239 djm 160:
161: while (waitpid(pid, NULL, 0) == -1)
162: if (errno != EINTR)
163: fatal("Couldn't wait for child: %s", strerror(errno));
164:
165: /* Set the connection file descriptors. */
166: packet_set_connection(sock, sock);
167:
168: return 0;
169: }
170:
1.39 deraadt 171: /*
172: * Connect to the given ssh server using a proxy command.
173: */
1.109 itojun 174: static int
1.124 markus 175: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 176: {
1.239 djm 177: char *command_string;
1.38 markus 178: int pin[2], pout[2];
1.69 deraadt 179: pid_t pid;
1.239 djm 180: char *shell;
1.237 markus 181:
1.226 djm 182: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 183: shell = _PATH_BSHELL;
1.38 markus 184:
185: /* Create pipes for communicating with the proxy. */
186: if (pipe(pin) < 0 || pipe(pout) < 0)
187: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 188: strerror(errno));
1.38 markus 189:
1.239 djm 190: command_string = expand_proxy_command(proxy_command, options.user,
191: host, port);
1.38 markus 192: debug("Executing proxy command: %.500s", command_string);
193:
194: /* Fork and execute the proxy command. */
195: if ((pid = fork()) == 0) {
196: char *argv[10];
197:
198: /* Child. Permanently give up superuser privileges. */
1.184 markus 199: permanently_drop_suid(original_real_uid);
1.38 markus 200:
201: /* Redirect stdin and stdout. */
202: close(pin[1]);
203: if (pin[0] != 0) {
204: if (dup2(pin[0], 0) < 0)
205: perror("dup2 stdin");
206: close(pin[0]);
207: }
208: close(pout[0]);
209: if (dup2(pout[1], 1) < 0)
210: perror("dup2 stdout");
211: /* Cannot be 1 because pin allocated two descriptors. */
212: close(pout[1]);
213:
214: /* Stderr is left as it is so that error messages get
215: printed on the user's terminal. */
1.201 djm 216: argv[0] = shell;
1.38 markus 217: argv[1] = "-c";
218: argv[2] = command_string;
219: argv[3] = NULL;
220:
221: /* Execute the proxy command. Note that we gave up any
222: extra privileges above. */
1.232 djm 223: signal(SIGPIPE, SIG_DFL);
1.89 markus 224: execv(argv[0], argv);
225: perror(argv[0]);
1.38 markus 226: exit(1);
227: }
228: /* Parent. */
229: if (pid < 0)
230: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 231: else
232: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 233:
234: /* Close child side of the descriptors. */
235: close(pin[0]);
236: close(pout[1]);
237:
238: /* Free the command name. */
1.238 djm 239: free(command_string);
1.38 markus 240:
241: /* Set the connection file descriptors. */
242: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 243:
1.110 markus 244: /* Indicate OK return */
245: return 0;
1.227 djm 246: }
247:
248: void
249: ssh_kill_proxy_command(void)
250: {
251: /*
252: * Send SIGHUP to proxy command if used. We don't wait() in
253: * case it hangs and instead rely on init to reap the child
254: */
255: if (proxy_command_pid > 1)
1.228 djm 256: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 257: }
258:
1.39 deraadt 259: /*
260: * Creates a (possibly privileged) socket for use as the ssh connection.
261: */
1.109 itojun 262: static int
1.139 markus 263: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 264: {
1.240 djm 265: int sock, r, gaierr;
1.246 djm 266: struct addrinfo hints, *res = NULL;
1.1 deraadt 267:
1.217 dtucker 268: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 269: if (sock < 0) {
1.240 djm 270: error("socket: %s", strerror(errno));
1.216 dtucker 271: return -1;
272: }
273: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 274:
275: /* Bind the socket to an alternative local IP address */
1.240 djm 276: if (options.bind_address == NULL && !privileged)
1.105 markus 277: return sock;
278:
1.246 djm 279: if (options.bind_address) {
280: memset(&hints, 0, sizeof(hints));
281: hints.ai_family = ai->ai_family;
282: hints.ai_socktype = ai->ai_socktype;
283: hints.ai_protocol = ai->ai_protocol;
284: hints.ai_flags = AI_PASSIVE;
285: gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
286: if (gaierr) {
287: error("getaddrinfo: %s: %s", options.bind_address,
288: ssh_gai_strerror(gaierr));
289: close(sock);
290: return -1;
291: }
1.105 markus 292: }
1.240 djm 293: /*
294: * If we are running as root and want to connect to a privileged
295: * port, bind our own socket to a privileged port.
296: */
297: if (privileged) {
298: PRIV_START;
1.246 djm 299: r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
1.240 djm 300: PRIV_END;
301: if (r < 0) {
302: error("bindresvport_sa: af=%d %s", ai->ai_family,
303: strerror(errno));
304: goto fail;
305: }
306: } else {
307: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
308: error("bind: %s: %s", options.bind_address,
309: strerror(errno));
310: fail:
311: close(sock);
312: freeaddrinfo(res);
313: return -1;
314: }
1.38 markus 315: }
1.246 djm 316: if (res != NULL)
317: freeaddrinfo(res);
1.38 markus 318: return sock;
1.1 deraadt 319: }
320:
1.141 djm 321: static int
322: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 323: socklen_t addrlen, int *timeoutp)
1.141 djm 324: {
325: fd_set *fdset;
1.202 djm 326: struct timeval tv, t_start;
1.141 djm 327: socklen_t optlen;
1.179 djm 328: int optval, rc, result = -1;
1.141 djm 329:
1.202 djm 330: gettimeofday(&t_start, NULL);
331:
332: if (*timeoutp <= 0) {
333: result = connect(sockfd, serv_addr, addrlen);
334: goto done;
335: }
1.141 djm 336:
1.156 djm 337: set_nonblock(sockfd);
1.141 djm 338: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 339: if (rc == 0) {
340: unset_nonblock(sockfd);
1.202 djm 341: result = 0;
342: goto done;
343: }
344: if (errno != EINPROGRESS) {
345: result = -1;
346: goto done;
1.156 djm 347: }
1.141 djm 348:
1.263 deraadt 349: fdset = xcalloc(howmany(sockfd + 1, NFDBITS),
1.179 djm 350: sizeof(fd_mask));
1.141 djm 351: FD_SET(sockfd, fdset);
1.202 djm 352: ms_to_timeval(&tv, *timeoutp);
1.141 djm 353:
1.162 deraadt 354: for (;;) {
1.141 djm 355: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
356: if (rc != -1 || errno != EINTR)
357: break;
358: }
359:
1.162 deraadt 360: switch (rc) {
1.141 djm 361: case 0:
362: /* Timed out */
363: errno = ETIMEDOUT;
1.142 djm 364: break;
1.141 djm 365: case -1:
366: /* Select error */
1.154 djm 367: debug("select: %s", strerror(errno));
1.142 djm 368: break;
1.141 djm 369: case 1:
370: /* Completed or failed */
371: optval = 0;
372: optlen = sizeof(optval);
1.154 djm 373: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 374: &optlen) == -1) {
1.154 djm 375: debug("getsockopt: %s", strerror(errno));
1.142 djm 376: break;
1.148 markus 377: }
1.141 djm 378: if (optval != 0) {
379: errno = optval;
1.142 djm 380: break;
1.141 djm 381: }
1.142 djm 382: result = 0;
1.156 djm 383: unset_nonblock(sockfd);
1.141 djm 384: break;
385: default:
386: /* Should not occur */
387: fatal("Bogus return (%d) from select()", rc);
388: }
389:
1.238 djm 390: free(fdset);
1.202 djm 391:
392: done:
393: if (result == 0 && *timeoutp > 0) {
394: ms_subtract_diff(&t_start, timeoutp);
395: if (*timeoutp <= 0) {
396: errno = ETIMEDOUT;
397: result = -1;
398: }
399: }
400:
1.142 djm 401: return (result);
1.141 djm 402: }
403:
1.39 deraadt 404: /*
1.49 markus 405: * Opens a TCP/IP connection to the remote server on the given host.
406: * The address of the remote host will be returned in hostaddr.
1.124 markus 407: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 408: * a privileged port will be allocated to make the connection.
1.124 markus 409: * This requires super-user privileges if needpriv is true.
1.39 deraadt 410: * Connection_attempts specifies the maximum number of tries (one per
411: * second). If proxy_command is non-NULL, it specifies the command (with %h
412: * and %p substituted for host and port, respectively) to use to contact
413: * the daemon.
414: */
1.241 djm 415: static int
416: ssh_connect_direct(const char *host, struct addrinfo *aitop,
417: struct sockaddr_storage *hostaddr, u_short port, int family,
418: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
1.1 deraadt 419: {
1.90 markus 420: int on = 1;
1.49 markus 421: int sock = -1, attempt;
1.90 markus 422: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 423: struct addrinfo *ai;
1.38 markus 424:
1.265 djm 425: debug2("%s: needpriv %d", __func__, needpriv);
1.268 djm 426: memset(ntop, 0, sizeof(ntop));
427: memset(strport, 0, sizeof(strport));
1.38 markus 428:
1.181 markus 429: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 430: if (attempt > 0) {
431: /* Sleep a moment before retrying. */
432: sleep(1);
1.38 markus 433: debug("Trying again...");
1.200 markus 434: }
1.181 markus 435: /*
436: * Loop through addresses for this host, and try each one in
437: * sequence until the connection succeeds.
438: */
1.49 markus 439: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 440: if (ai->ai_family != AF_INET &&
441: ai->ai_family != AF_INET6)
1.49 markus 442: continue;
443: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
444: ntop, sizeof(ntop), strport, sizeof(strport),
445: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.265 djm 446: error("%s: getnameinfo failed", __func__);
1.49 markus 447: continue;
448: }
449: debug("Connecting to %.200s [%.100s] port %s.",
450: host, ntop, strport);
451:
452: /* Create a socket for connecting. */
1.139 markus 453: sock = ssh_create_socket(needpriv, ai);
1.49 markus 454: if (sock < 0)
1.110 markus 455: /* Any error is already output */
1.49 markus 456: continue;
457:
1.141 djm 458: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 459: timeout_ms) >= 0) {
1.49 markus 460: /* Successful connection. */
1.102 markus 461: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 462: break;
1.49 markus 463: } else {
1.131 itojun 464: debug("connect to address %s port %s: %s",
465: ntop, strport, strerror(errno));
1.38 markus 466: close(sock);
1.181 markus 467: sock = -1;
1.38 markus 468: }
469: }
1.181 markus 470: if (sock != -1)
1.49 markus 471: break; /* Successful connection. */
1.38 markus 472: }
1.49 markus 473:
1.38 markus 474: /* Return failure if we didn't get a successful connection. */
1.181 markus 475: if (sock == -1) {
1.159 markus 476: error("ssh: connect to host %s port %s: %s",
1.130 itojun 477: host, strport, strerror(errno));
1.159 markus 478: return (-1);
1.130 itojun 479: }
1.38 markus 480:
481: debug("Connection established.");
1.90 markus 482:
1.155 markus 483: /* Set SO_KEEPALIVE if requested. */
1.202 djm 484: if (want_keepalive &&
1.90 markus 485: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
486: sizeof(on)) < 0)
487: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 488:
489: /* Set the connection. */
490: packet_set_connection(sock, sock);
1.1 deraadt 491:
1.110 markus 492: return 0;
1.59 markus 493: }
494:
1.241 djm 495: int
496: ssh_connect(const char *host, struct addrinfo *addrs,
497: struct sockaddr_storage *hostaddr, u_short port, int family,
498: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
499: {
500: if (options.proxy_command == NULL) {
501: return ssh_connect_direct(host, addrs, hostaddr, port, family,
502: connection_attempts, timeout_ms, want_keepalive, needpriv);
503: } else if (strcmp(options.proxy_command, "-") == 0) {
504: packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
505: return 0; /* Always succeeds */
506: } else if (options.proxy_use_fdpass) {
507: return ssh_proxy_fdpass_connect(host, port,
508: options.proxy_command);
509: }
510: return ssh_proxy_connect(host, port, options.proxy_command);
511: }
512:
1.235 djm 513: static void
514: send_client_banner(int connection_out, int minor1)
515: {
516: /* Send our own protocol version identification. */
517: if (compat20) {
518: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
519: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
520: } else {
521: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\n",
522: PROTOCOL_MAJOR_1, minor1, SSH_VERSION);
523: }
1.270 markus 524: if (atomicio(vwrite, connection_out, client_version_string,
1.235 djm 525: strlen(client_version_string)) != strlen(client_version_string))
526: fatal("write: %.100s", strerror(errno));
527: chop(client_version_string);
528: debug("Local version string %.100s", client_version_string);
529: }
530:
1.43 markus 531: /*
1.39 deraadt 532: * Waits for the server identification string, and sends our own
533: * identification string.
534: */
1.213 andreas 535: void
1.202 djm 536: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 537: {
1.38 markus 538: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 539: int remote_major, remote_minor, mismatch;
1.38 markus 540: int connection_in = packet_get_connection_in();
541: int connection_out = packet_get_connection_out();
1.235 djm 542: int minor1 = PROTOCOL_MINOR_1, client_banner_sent = 0;
1.185 djm 543: u_int i, n;
1.202 djm 544: size_t len;
545: int fdsetsz, remaining, rc;
546: struct timeval t_start, t_remaining;
547: fd_set *fdset;
548:
549: fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
550: fdset = xcalloc(1, fdsetsz);
1.38 markus 551:
1.235 djm 552: /*
553: * If we are SSH2-only then we can send the banner immediately and
554: * save a round-trip.
555: */
556: if (options.protocol == SSH_PROTO_2) {
557: enable_compat20();
558: send_client_banner(connection_out, 0);
559: client_banner_sent = 1;
560: }
561:
1.163 avsm 562: /* Read other side's version identification. */
1.202 djm 563: remaining = timeout_ms;
1.185 djm 564: for (n = 0;;) {
1.75 markus 565: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 566: if (timeout_ms > 0) {
567: gettimeofday(&t_start, NULL);
568: ms_to_timeval(&t_remaining, remaining);
569: FD_SET(connection_in, fdset);
570: rc = select(connection_in + 1, fdset, NULL,
571: fdset, &t_remaining);
572: ms_subtract_diff(&t_start, &remaining);
573: if (rc == 0 || remaining <= 0)
574: fatal("Connection timed out during "
575: "banner exchange");
576: if (rc == -1) {
577: if (errno == EINTR)
578: continue;
579: fatal("ssh_exchange_identification: "
580: "select: %s", strerror(errno));
581: }
582: }
583:
1.270 markus 584: len = atomicio(read, connection_in, &buf[i], 1);
1.163 avsm 585:
1.167 djm 586: if (len != 1 && errno == EPIPE)
1.202 djm 587: fatal("ssh_exchange_identification: "
588: "Connection closed by remote host");
1.163 avsm 589: else if (len != 1)
1.202 djm 590: fatal("ssh_exchange_identification: "
591: "read: %.100s", strerror(errno));
1.75 markus 592: if (buf[i] == '\r') {
593: buf[i] = '\n';
594: buf[i + 1] = 0;
595: continue; /**XXX wait for \n */
596: }
597: if (buf[i] == '\n') {
598: buf[i + 1] = 0;
599: break;
600: }
1.185 djm 601: if (++n > 65536)
1.202 djm 602: fatal("ssh_exchange_identification: "
603: "No banner received");
1.38 markus 604: }
1.75 markus 605: buf[sizeof(buf) - 1] = 0;
1.76 markus 606: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 607: break;
1.75 markus 608: debug("ssh_exchange_identification: %s", buf);
1.38 markus 609: }
1.59 markus 610: server_version_string = xstrdup(buf);
1.238 djm 611: free(fdset);
1.38 markus 612:
1.40 markus 613: /*
614: * Check that the versions match. In future this might accept
615: * several versions and set appropriate flags to handle them.
616: */
1.59 markus 617: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
618: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 619: fatal("Bad remote protocol version identification: '%.100s'", buf);
620: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 621: remote_major, remote_minor, remote_version);
1.38 markus 622:
1.255 markus 623: active_state->compat = compat_datafellows(remote_version);
1.64 markus 624: mismatch = 0;
1.59 markus 625:
1.116 deraadt 626: switch (remote_major) {
1.64 markus 627: case 1:
628: if (remote_minor == 99 &&
629: (options.protocol & SSH_PROTO_2) &&
630: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
631: enable_compat20();
632: break;
633: }
634: if (!(options.protocol & SSH_PROTO_1)) {
635: mismatch = 1;
636: break;
637: }
638: if (remote_minor < 3) {
639: fatal("Remote machine has too old SSH software version.");
1.81 markus 640: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 641: /* We speak 1.3, too. */
642: enable_compat13();
1.81 markus 643: minor1 = 3;
1.64 markus 644: if (options.forward_agent) {
1.138 itojun 645: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 646: options.forward_agent = 0;
647: }
648: }
649: break;
650: case 2:
651: if (options.protocol & SSH_PROTO_2) {
652: enable_compat20();
653: break;
1.38 markus 654: }
1.64 markus 655: /* FALLTHROUGH */
1.68 markus 656: default:
1.64 markus 657: mismatch = 1;
658: break;
1.38 markus 659: }
1.64 markus 660: if (mismatch)
1.38 markus 661: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 662: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
663: remote_major);
1.244 djm 664: if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
665: fatal("Server version \"%.100s\" uses unsafe key agreement; "
666: "refusing connection", remote_version);
1.243 djm 667: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
668: logit("Server version \"%.100s\" uses unsafe RSA signature "
669: "scheme; disabling use of RSA keys", remote_version);
1.235 djm 670: if (!client_banner_sent)
671: send_client_banner(connection_out, minor1);
1.59 markus 672: chop(server_version_string);
1.1 deraadt 673: }
674:
1.96 markus 675: /* defaults to 'no' */
1.109 itojun 676: static int
1.112 markus 677: confirm(const char *prompt)
1.1 deraadt 678: {
1.119 markus 679: const char *msg, *again = "Please type 'yes' or 'no': ";
680: char *p;
681: int ret = -1;
1.96 markus 682:
683: if (options.batch_mode)
684: return 0;
1.119 markus 685: for (msg = prompt;;msg = again) {
686: p = read_passphrase(msg, RP_ECHO);
687: if (p == NULL ||
688: (p[0] == '\0') || (p[0] == '\n') ||
689: strncasecmp(p, "no", 2) == 0)
690: ret = 0;
1.127 markus 691: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 692: ret = 1;
1.238 djm 693: free(p);
1.119 markus 694: if (ret != -1)
695: return ret;
1.1 deraadt 696: }
697: }
698:
1.219 djm 699: static int
700: check_host_cert(const char *host, const Key *host_key)
701: {
702: const char *reason;
703:
704: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
705: error("%s", reason);
706: return 0;
707: }
1.249 djm 708: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 709: error("Certificate for %s contains unsupported "
710: "critical options(s)", host);
1.219 djm 711: return 0;
712: }
713: return 1;
714: }
715:
1.229 djm 716: static int
717: sockaddr_is_local(struct sockaddr *hostaddr)
718: {
719: switch (hostaddr->sa_family) {
720: case AF_INET:
721: return (ntohl(((struct sockaddr_in *)hostaddr)->
722: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
723: case AF_INET6:
724: return IN6_IS_ADDR_LOOPBACK(
725: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
726: default:
727: return 0;
728: }
729: }
730:
731: /*
732: * Prepare the hostname and ip address strings that are used to lookup
733: * host keys in known_hosts files. These may have a port number appended.
734: */
735: void
736: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
737: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
738: {
739: char ntop[NI_MAXHOST];
740:
741: /*
742: * We don't have the remote ip-address for connections
743: * using a proxy command
744: */
745: if (hostfile_ipaddr != NULL) {
746: if (options.proxy_command == NULL) {
747: if (getnameinfo(hostaddr, hostaddr->sa_len,
748: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 749: fatal("%s: getnameinfo failed", __func__);
1.229 djm 750: *hostfile_ipaddr = put_host_port(ntop, port);
751: } else {
752: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
753: "command>");
754: }
755: }
756:
757: /*
758: * Allow the user to record the key under a different name or
759: * differentiate a non-standard port. This is useful for ssh
760: * tunneling over forwarded connections or if you run multiple
761: * sshd's on different ports on the same machine.
762: */
763: if (hostfile_hostname != NULL) {
764: if (options.host_key_alias != NULL) {
765: *hostfile_hostname = xstrdup(options.host_key_alias);
766: debug("using hostkeyalias: %s", *hostfile_hostname);
767: } else {
768: *hostfile_hostname = put_host_port(hostname, port);
769: }
770: }
771: }
772:
1.39 deraadt 773: /*
1.108 markus 774: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 775: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 776: */
1.197 dtucker 777: #define RDRW 0
778: #define RDONLY 1
779: #define ROQUIET 2
1.109 itojun 780: static int
1.197 dtucker 781: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.234 djm 782: Key *host_key, int readonly,
783: char **user_hostfiles, u_int num_user_hostfiles,
784: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 785: {
1.234 djm 786: HostStatus host_status;
787: HostStatus ip_status;
1.229 djm 788: Key *raw_key = NULL;
1.189 dtucker 789: char *ip = NULL, *host = NULL;
1.204 grunk 790: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 791: char msg[1024];
1.234 djm 792: const char *type;
793: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 794: int len, cancelled_forwarding = 0;
1.234 djm 795: int local = sockaddr_is_local(hostaddr);
796: int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
1.257 djm 797: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 798: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 799: u_int i;
1.49 markus 800:
801: /*
802: * Force accepting of the host key for loopback/localhost. The
803: * problem is that if the home directory is NFS-mounted to multiple
804: * machines, localhost will refer to a different machine in each of
805: * them, and the user will get bogus HOST_CHANGED warnings. This
806: * essentially disables host authentication for localhost; however,
807: * this is probably not a real problem.
808: */
1.111 markus 809: if (options.no_host_authentication_for_localhost == 1 && local &&
810: options.host_key_alias == NULL) {
1.88 markus 811: debug("Forcing accepting of host key for "
812: "loopback/localhost.");
1.108 markus 813: return 0;
1.49 markus 814: }
1.42 markus 815:
816: /*
1.229 djm 817: * Prepare the hostname and address strings used for hostkey lookup.
818: * In some cases, these will have a port number appended.
1.42 markus 819: */
1.229 djm 820: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 821:
822: /*
1.88 markus 823: * Turn off check_host_ip if the connection is to localhost, via proxy
824: * command or if we don't have a hostname to compare with
825: */
1.189 dtucker 826: if (options.check_host_ip && (local ||
827: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 828: options.check_host_ip = 0;
1.86 markus 829:
1.229 djm 830: host_hostkeys = init_hostkeys();
1.234 djm 831: for (i = 0; i < num_user_hostfiles; i++)
832: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
833: for (i = 0; i < num_system_hostfiles; i++)
834: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 835:
836: ip_hostkeys = NULL;
837: if (!want_cert && options.check_host_ip) {
838: ip_hostkeys = init_hostkeys();
1.234 djm 839: for (i = 0; i < num_user_hostfiles; i++)
840: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
841: for (i = 0; i < num_system_hostfiles; i++)
842: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 843: }
1.38 markus 844:
1.219 djm 845: retry:
1.229 djm 846: /* Reload these as they may have changed on cert->key downgrade */
1.219 djm 847: want_cert = key_is_cert(host_key);
848: type = key_type(host_key);
849:
1.46 markus 850: /*
1.170 djm 851: * Check if the host key is present in the user's list of known
1.40 markus 852: * hosts or in the systemwide list.
853: */
1.229 djm 854: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
855: &host_found);
856:
1.40 markus 857: /*
858: * Also perform check for the ip address, skip the check if we are
1.219 djm 859: * localhost, looking for a certificate, or the hostname was an ip
860: * address to begin with.
1.40 markus 861: */
1.229 djm 862: if (!want_cert && ip_hostkeys != NULL) {
863: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
864: &ip_found);
1.38 markus 865: if (host_status == HOST_CHANGED &&
1.229 djm 866: (ip_status != HOST_CHANGED ||
867: (ip_found != NULL &&
868: !key_equal(ip_found->key, host_found->key))))
1.38 markus 869: host_ip_differ = 1;
870: } else
871: ip_status = host_status;
872:
873: switch (host_status) {
874: case HOST_OK:
875: /* The host is known and the key matches. */
1.219 djm 876: debug("Host '%.200s' is known and matches the %s host %s.",
877: host, type, want_cert ? "certificate" : "key");
1.229 djm 878: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
879: host_found->file, host_found->line);
1.219 djm 880: if (want_cert && !check_host_cert(hostname, host_key))
881: goto fail;
1.88 markus 882: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 883: if (readonly || want_cert)
1.138 itojun 884: logit("%s host key for IP address "
1.108 markus 885: "'%.128s' not in list of known hosts.",
886: type, ip);
1.234 djm 887: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 888: host_key, options.hash_known_hosts))
1.138 itojun 889: logit("Failed to add the %s host key for IP "
1.108 markus 890: "address '%.128s' to the list of known "
1.262 dtucker 891: "hosts (%.500s).", type, ip,
1.234 djm 892: user_hostfiles[0]);
1.88 markus 893: else
1.138 itojun 894: logit("Warning: Permanently added the %s host "
1.108 markus 895: "key for IP address '%.128s' to the list "
896: "of known hosts.", type, ip);
1.209 grunk 897: } else if (options.visual_host_key) {
1.259 djm 898: fp = sshkey_fingerprint(host_key,
1.254 djm 899: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 900: ra = sshkey_fingerprint(host_key,
1.254 djm 901: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 902: if (fp == NULL || ra == NULL)
903: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 904: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 905: free(ra);
906: free(fp);
1.38 markus 907: }
1.257 djm 908: hostkey_trusted = 1;
1.38 markus 909: break;
910: case HOST_NEW:
1.197 dtucker 911: if (options.host_key_alias == NULL && port != 0 &&
912: port != SSH_DEFAULT_PORT) {
913: debug("checking without port identifier");
1.212 stevesk 914: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 915: ROQUIET, user_hostfiles, num_user_hostfiles,
916: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 917: debug("found matching key w/out port");
918: break;
919: }
920: }
1.219 djm 921: if (readonly || want_cert)
1.108 markus 922: goto fail;
1.38 markus 923: /* The host is new. */
924: if (options.strict_host_key_checking == 1) {
1.108 markus 925: /*
926: * User has requested strict host key checking. We
927: * will not add the host key automatically. The only
928: * alternative left is to abort.
929: */
930: error("No %s host key is known for %.200s and you "
931: "have requested strict checking.", type, host);
932: goto fail;
1.38 markus 933: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 934: char msg1[1024], msg2[1024];
935:
1.229 djm 936: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 937: snprintf(msg1, sizeof(msg1),
1.168 djm 938: "\nbut keys of different type are already"
939: " known for this host.");
1.145 jakob 940: else
941: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 942: /* The default */
1.259 djm 943: fp = sshkey_fingerprint(host_key,
1.254 djm 944: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 945: ra = sshkey_fingerprint(host_key,
1.254 djm 946: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 947: if (fp == NULL || ra == NULL)
948: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 949: msg2[0] = '\0';
950: if (options.verify_host_key_dns) {
1.153 jakob 951: if (matching_host_key_dns)
1.145 jakob 952: snprintf(msg2, sizeof(msg2),
953: "Matching host key fingerprint"
954: " found in DNS.\n");
955: else
956: snprintf(msg2, sizeof(msg2),
957: "No matching host key fingerprint"
958: " found in DNS.\n");
959: }
1.119 markus 960: snprintf(msg, sizeof(msg),
1.108 markus 961: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 962: "established%s\n"
1.209 grunk 963: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 964: "Are you sure you want to continue connecting "
1.132 markus 965: "(yes/no)? ",
1.209 grunk 966: host, ip, msg1, type, fp,
967: options.visual_host_key ? "\n" : "",
968: options.visual_host_key ? ra : "",
969: msg2);
1.238 djm 970: free(ra);
971: free(fp);
1.119 markus 972: if (!confirm(msg))
1.108 markus 973: goto fail;
1.257 djm 974: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 975: }
1.161 djm 976: /*
977: * If not in strict mode, add the key automatically to the
978: * local known_hosts file.
979: */
1.88 markus 980: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 981: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 982: hostp = hostline;
1.161 djm 983: if (options.hash_known_hosts) {
984: /* Add hash of host and IP separately */
1.234 djm 985: r = add_host_to_hostfile(user_hostfiles[0],
986: host, host_key, options.hash_known_hosts) &&
987: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 988: host_key, options.hash_known_hosts);
989: } else {
990: /* Add unhashed "host,ip" */
1.234 djm 991: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 992: hostline, host_key,
993: options.hash_known_hosts);
994: }
995: } else {
1.234 djm 996: r = add_host_to_hostfile(user_hostfiles[0], host,
997: host_key, options.hash_known_hosts);
1.38 markus 998: hostp = host;
1.161 djm 999: }
1.38 markus 1000:
1.161 djm 1001: if (!r)
1.138 itojun 1002: logit("Failed to add the host to the list of known "
1.234 djm 1003: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 1004: else
1.138 itojun 1005: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 1006: "list of known hosts.", hostp, type);
1.38 markus 1007: break;
1.220 djm 1008: case HOST_REVOKED:
1009: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1010: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1011: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1012: error("The %s host key for %s is marked as revoked.", type, host);
1013: error("This could mean that a stolen key is being used to");
1014: error("impersonate this host.");
1015:
1016: /*
1017: * If strict host key checking is in use, the user will have
1018: * to edit the key manually and we can only abort.
1019: */
1020: if (options.strict_host_key_checking) {
1021: error("%s host key for %.200s was revoked and you have "
1022: "requested strict checking.", type, host);
1023: goto fail;
1024: }
1025: goto continue_unsafe;
1026:
1.38 markus 1027: case HOST_CHANGED:
1.219 djm 1028: if (want_cert) {
1029: /*
1030: * This is only a debug() since it is valid to have
1031: * CAs with wildcard DNS matches that don't match
1032: * all hosts that one might visit.
1033: */
1034: debug("Host certificate authority does not "
1.229 djm 1035: "match %s in %s:%lu", CA_MARKER,
1036: host_found->file, host_found->line);
1.219 djm 1037: goto fail;
1038: }
1.197 dtucker 1039: if (readonly == ROQUIET)
1040: goto fail;
1.38 markus 1041: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1042: char *key_msg;
1.38 markus 1043: if (ip_status == HOST_NEW)
1.158 avsm 1044: key_msg = "is unknown";
1.38 markus 1045: else if (ip_status == HOST_OK)
1.158 avsm 1046: key_msg = "is unchanged";
1.38 markus 1047: else
1.158 avsm 1048: key_msg = "has a different value";
1.38 markus 1049: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1050: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1051: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1052: error("The %s host key for %s has changed,", type, host);
1.208 ian 1053: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1054: error("%s. This could either mean that", key_msg);
1.38 markus 1055: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1056: error("and its host key have changed at the same time.");
1.88 markus 1057: if (ip_status != HOST_NEW)
1.229 djm 1058: error("Offending key for IP in %s:%lu",
1059: ip_found->file, ip_found->line);
1.38 markus 1060: }
1061: /* The host key has changed. */
1.150 jakob 1062: warn_changed_key(host_key);
1.38 markus 1063: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1064: user_hostfiles[0]);
1.229 djm 1065: error("Offending %s key in %s:%lu", key_type(host_found->key),
1066: host_found->file, host_found->line);
1.38 markus 1067:
1.40 markus 1068: /*
1069: * If strict host key checking is in use, the user will have
1070: * to edit the key manually and we can only abort.
1071: */
1.108 markus 1072: if (options.strict_host_key_checking) {
1073: error("%s host key for %.200s has changed and you have "
1074: "requested strict checking.", type, host);
1075: goto fail;
1076: }
1.38 markus 1077:
1.220 djm 1078: continue_unsafe:
1.40 markus 1079: /*
1080: * If strict host key checking has not been requested, allow
1.144 djm 1081: * the connection but without MITM-able authentication or
1.194 stevesk 1082: * forwarding.
1.40 markus 1083: */
1.38 markus 1084: if (options.password_authentication) {
1.108 markus 1085: error("Password authentication is disabled to avoid "
1086: "man-in-the-middle attacks.");
1.38 markus 1087: options.password_authentication = 0;
1.210 dtucker 1088: cancelled_forwarding = 1;
1.144 djm 1089: }
1090: if (options.kbd_interactive_authentication) {
1091: error("Keyboard-interactive authentication is disabled"
1092: " to avoid man-in-the-middle attacks.");
1093: options.kbd_interactive_authentication = 0;
1094: options.challenge_response_authentication = 0;
1.210 dtucker 1095: cancelled_forwarding = 1;
1.144 djm 1096: }
1097: if (options.challenge_response_authentication) {
1098: error("Challenge/response authentication is disabled"
1099: " to avoid man-in-the-middle attacks.");
1100: options.challenge_response_authentication = 0;
1.210 dtucker 1101: cancelled_forwarding = 1;
1.38 markus 1102: }
1103: if (options.forward_agent) {
1.108 markus 1104: error("Agent forwarding is disabled to avoid "
1105: "man-in-the-middle attacks.");
1.38 markus 1106: options.forward_agent = 0;
1.210 dtucker 1107: cancelled_forwarding = 1;
1.83 markus 1108: }
1109: if (options.forward_x11) {
1.108 markus 1110: error("X11 forwarding is disabled to avoid "
1111: "man-in-the-middle attacks.");
1.83 markus 1112: options.forward_x11 = 0;
1.210 dtucker 1113: cancelled_forwarding = 1;
1.83 markus 1114: }
1.108 markus 1115: if (options.num_local_forwards > 0 ||
1116: options.num_remote_forwards > 0) {
1117: error("Port forwarding is disabled to avoid "
1118: "man-in-the-middle attacks.");
1119: options.num_local_forwards =
1.118 deraadt 1120: options.num_remote_forwards = 0;
1.210 dtucker 1121: cancelled_forwarding = 1;
1.194 stevesk 1122: }
1123: if (options.tun_open != SSH_TUNMODE_NO) {
1124: error("Tunnel forwarding is disabled to avoid "
1125: "man-in-the-middle attacks.");
1126: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1127: cancelled_forwarding = 1;
1.38 markus 1128: }
1.210 dtucker 1129: if (options.exit_on_forward_failure && cancelled_forwarding)
1130: fatal("Error: forwarding disabled due to host key "
1131: "check failure");
1132:
1.40 markus 1133: /*
1134: * XXX Should permit the user to change to use the new id.
1135: * This could be done by converting the host key to an
1136: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1137: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1138: * accept the authentication.
1139: */
1.38 markus 1140: break;
1.132 markus 1141: case HOST_FOUND:
1142: fatal("internal error");
1143: break;
1.88 markus 1144: }
1145:
1146: if (options.check_host_ip && host_status != HOST_CHANGED &&
1147: ip_status == HOST_CHANGED) {
1.119 markus 1148: snprintf(msg, sizeof(msg),
1149: "Warning: the %s host key for '%.200s' "
1150: "differs from the key for the IP address '%.128s'"
1.229 djm 1151: "\nOffending key for IP in %s:%lu",
1152: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1153: if (host_status == HOST_OK) {
1154: len = strlen(msg);
1155: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1156: "\nMatching host key in %s:%lu",
1157: host_found->file, host_found->line);
1.119 markus 1158: }
1.88 markus 1159: if (options.strict_host_key_checking == 1) {
1.143 djm 1160: logit("%s", msg);
1.108 markus 1161: error("Exiting, you have requested strict checking.");
1162: goto fail;
1.88 markus 1163: } else if (options.strict_host_key_checking == 2) {
1.119 markus 1164: strlcat(msg, "\nAre you sure you want "
1165: "to continue connecting (yes/no)? ", sizeof(msg));
1166: if (!confirm(msg))
1.108 markus 1167: goto fail;
1.119 markus 1168: } else {
1.143 djm 1169: logit("%s", msg);
1.88 markus 1170: }
1.257 djm 1171: }
1172:
1173: if (!hostkey_trusted && options.update_hostkeys) {
1174: debug("%s: hostkey not known or explicitly trusted: "
1175: "disabling UpdateHostkeys", __func__);
1176: options.update_hostkeys = 0;
1.38 markus 1177: }
1.82 provos 1178:
1.238 djm 1179: free(ip);
1180: free(host);
1.229 djm 1181: if (host_hostkeys != NULL)
1182: free_hostkeys(host_hostkeys);
1183: if (ip_hostkeys != NULL)
1184: free_hostkeys(ip_hostkeys);
1.108 markus 1185: return 0;
1186:
1187: fail:
1.220 djm 1188: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1189: /*
1190: * No matching certificate. Downgrade cert to raw key and
1191: * search normally.
1192: */
1193: debug("No matching CA found. Retry with plain key");
1194: raw_key = key_from_private(host_key);
1195: if (key_drop_cert(raw_key) != 0)
1196: fatal("Couldn't drop certificate");
1197: host_key = raw_key;
1198: goto retry;
1199: }
1200: if (raw_key != NULL)
1201: key_free(raw_key);
1.238 djm 1202: free(ip);
1203: free(host);
1.229 djm 1204: if (host_hostkeys != NULL)
1205: free_hostkeys(host_hostkeys);
1206: if (ip_hostkeys != NULL)
1207: free_hostkeys(ip_hostkeys);
1.108 markus 1208: return -1;
1209: }
1210:
1.140 jakob 1211: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1212: int
1213: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1214: {
1.267 djm 1215: u_int i;
1.250 djm 1216: int r = -1, flags = 0;
1.267 djm 1217: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1218: struct sshkey *plain = NULL;
1.229 djm 1219:
1.252 djm 1220: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1221: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1222: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1223: r = -1;
1224: goto out;
1225: }
1226:
1.267 djm 1227: if (sshkey_is_cert(host_key)) {
1228: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1229: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1230: error("%s: fingerprint CA key: %s",
1231: __func__, ssh_err(r));
1232: r = -1;
1233: goto out;
1234: }
1235: sshkey_format_cert_validity(host_key->cert,
1236: valid, sizeof(valid));
1237: debug("Server host certificate: %s %s, serial %llu "
1238: "ID \"%s\" CA %s %s valid %s",
1239: sshkey_ssh_name(host_key), fp,
1.269 djm 1240: (unsigned long long)host_key->cert->serial,
1241: host_key->cert->key_id,
1.267 djm 1242: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1243: valid);
1244: for (i = 0; i < host_key->cert->nprincipals; i++) {
1245: debug2("Server host certificate hostname: %s",
1246: host_key->cert->principals[i]);
1247: }
1248: } else {
1249: debug("Server host key: %s %s", compat20 ?
1250: sshkey_ssh_name(host_key) : sshkey_type(host_key), fp);
1251: }
1.252 djm 1252:
1253: if (sshkey_equal(previous_host_key, host_key)) {
1254: debug2("%s: server host key %s %s matches cached key",
1255: __func__, sshkey_type(host_key), fp);
1256: r = 0;
1257: goto out;
1258: }
1259:
1260: /* Check in RevokedHostKeys file if specified */
1261: if (options.revoked_host_keys != NULL) {
1262: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1263: switch (r) {
1264: case 0:
1265: break; /* not revoked */
1266: case SSH_ERR_KEY_REVOKED:
1267: error("Host key %s %s revoked by file %s",
1268: sshkey_type(host_key), fp,
1269: options.revoked_host_keys);
1270: r = -1;
1271: goto out;
1272: default:
1273: error("Error checking host key %s %s in "
1274: "revoked keys file %s: %s", sshkey_type(host_key),
1275: fp, options.revoked_host_keys, ssh_err(r));
1276: r = -1;
1277: goto out;
1278: }
1.250 djm 1279: }
1280:
1.247 djm 1281: if (options.verify_host_key_dns) {
1282: /*
1283: * XXX certs are not yet supported for DNS, so downgrade
1284: * them and try the plain key.
1285: */
1.252 djm 1286: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1287: goto out;
1288: if (sshkey_is_cert(plain))
1289: sshkey_drop_cert(plain);
1.247 djm 1290: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1291: if (flags & DNS_VERIFY_FOUND) {
1292: if (options.verify_host_key_dns == 1 &&
1293: flags & DNS_VERIFY_MATCH &&
1294: flags & DNS_VERIFY_SECURE) {
1.250 djm 1295: r = 0;
1.252 djm 1296: goto out;
1.247 djm 1297: }
1298: if (flags & DNS_VERIFY_MATCH) {
1299: matching_host_key_dns = 1;
1300: } else {
1301: warn_changed_key(plain);
1302: error("Update the SSHFP RR in DNS "
1303: "with the new host key to get rid "
1304: "of this message.");
1305: }
1.153 jakob 1306: }
1.140 jakob 1307: }
1308: }
1.250 djm 1309: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1310: options.user_hostfiles, options.num_user_hostfiles,
1311: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1312:
1.252 djm 1313: out:
1314: sshkey_free(plain);
1315: free(fp);
1.267 djm 1316: free(cafp);
1.250 djm 1317: if (r == 0 && host_key != NULL) {
1318: key_free(previous_host_key);
1319: previous_host_key = key_from_private(host_key);
1320: }
1321:
1322: return r;
1.51 markus 1323: }
1.70 markus 1324:
1.51 markus 1325: /*
1326: * Starts a dialog with the server, and authenticates the current user on the
1327: * server. This does not need any extra privileges. The basic connection
1328: * to the server must already have been established before this is called.
1329: * If login fails, this function prints an error and never returns.
1330: * This function does not require super-user privileges.
1331: */
1332: void
1.120 markus 1333: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1334: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1335: {
1.241 djm 1336: char *host;
1.70 markus 1337: char *server_user, *local_user;
1338:
1339: local_user = xstrdup(pw->pw_name);
1340: server_user = options.user ? options.user : local_user;
1.51 markus 1341:
1342: /* Convert the user-supplied hostname into all lowercase. */
1343: host = xstrdup(orighost);
1.241 djm 1344: lowercase(host);
1.51 markus 1345:
1346: /* Exchange protocol version identification strings with the server. */
1.202 djm 1347: ssh_exchange_identification(timeout_ms);
1.51 markus 1348:
1349: /* Put the connection into non-blocking mode. */
1350: packet_set_nonblocking();
1351:
1352: /* key exchange */
1353: /* authenticate user */
1.261 dtucker 1354: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.59 markus 1355: if (compat20) {
1.229 djm 1356: ssh_kex2(host, hostaddr, port);
1.120 markus 1357: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 1358: } else {
1.260 djm 1359: fatal("ssh1 is not supported");
1.59 markus 1360: }
1.238 djm 1361: free(local_user);
1.97 markus 1362: }
1363:
1364: void
1365: ssh_put_password(char *password)
1366: {
1367: int size;
1368: char *padded;
1369:
1.99 deraadt 1370: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1371: packet_put_cstring(password);
1.99 deraadt 1372: return;
1373: }
1.272 deraadt 1374: size = ROUNDUP(strlen(password) + 1, 32);
1.179 djm 1375: padded = xcalloc(1, size);
1.97 markus 1376: strlcpy(padded, password, size);
1377: packet_put_string(padded, size);
1.245 djm 1378: explicit_bzero(padded, size);
1.238 djm 1379: free(padded);
1.132 markus 1380: }
1381:
1382: /* print all known host keys for a given host, but skip keys of given type */
1383: static int
1.229 djm 1384: show_other_keys(struct hostkeys *hostkeys, Key *key)
1.132 markus 1385: {
1.242 djm 1386: int type[] = {
1387: KEY_RSA1,
1388: KEY_RSA,
1389: KEY_DSA,
1390: KEY_ECDSA,
1391: KEY_ED25519,
1392: -1
1393: };
1.229 djm 1394: int i, ret = 0;
1395: char *fp, *ra;
1396: const struct hostkey_entry *found;
1.132 markus 1397:
1398: for (i = 0; type[i] != -1; i++) {
1399: if (type[i] == key->type)
1400: continue;
1.229 djm 1401: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1402: continue;
1.259 djm 1403: fp = sshkey_fingerprint(found->key,
1.254 djm 1404: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1405: ra = sshkey_fingerprint(found->key,
1.254 djm 1406: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1407: if (fp == NULL || ra == NULL)
1408: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1409: logit("WARNING: %s key found for host %s\n"
1410: "in %s:%lu\n"
1411: "%s key fingerprint %s.",
1412: key_type(found->key),
1413: found->host, found->file, found->line,
1414: key_type(found->key), fp);
1415: if (options.visual_host_key)
1416: logit("%s", ra);
1.238 djm 1417: free(ra);
1418: free(fp);
1.229 djm 1419: ret = 1;
1.132 markus 1420: }
1.229 djm 1421: return ret;
1.150 jakob 1422: }
1423:
1424: static void
1425: warn_changed_key(Key *host_key)
1426: {
1427: char *fp;
1428:
1.259 djm 1429: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1430: SSH_FP_DEFAULT);
1.259 djm 1431: if (fp == NULL)
1432: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1433:
1434: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1435: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1436: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1437: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1438: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1439: error("It is also possible that a host key has just been changed.");
1.150 jakob 1440: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.230 markus 1441: key_type(host_key), fp);
1.150 jakob 1442: error("Please contact your system administrator.");
1443:
1.238 djm 1444: free(fp);
1.171 reyk 1445: }
1446:
1447: /*
1448: * Execute a local command
1449: */
1450: int
1451: ssh_local_cmd(const char *args)
1452: {
1453: char *shell;
1454: pid_t pid;
1455: int status;
1.231 djm 1456: void (*osighand)(int);
1.171 reyk 1457:
1458: if (!options.permit_local_command ||
1459: args == NULL || !*args)
1460: return (1);
1461:
1.226 djm 1462: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1463: shell = _PATH_BSHELL;
1464:
1.231 djm 1465: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1466: pid = fork();
1467: if (pid == 0) {
1.232 djm 1468: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1469: debug3("Executing %s -c \"%s\"", shell, args);
1470: execl(shell, shell, "-c", args, (char *)NULL);
1471: error("Couldn't execute %s -c \"%s\": %s",
1472: shell, args, strerror(errno));
1473: _exit(1);
1474: } else if (pid == -1)
1475: fatal("fork failed: %.100s", strerror(errno));
1476: while (waitpid(pid, &status, 0) == -1)
1477: if (errno != EINTR)
1478: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1479: signal(SIGCHLD, osighand);
1.171 reyk 1480:
1481: if (!WIFEXITED(status))
1482: return (1);
1483:
1484: return (WEXITSTATUS(status));
1.266 jcs 1485: }
1486:
1487: void
1488: maybe_add_key_to_agent(char *authfile, Key *private, char *comment,
1489: char *passphrase)
1490: {
1491: int auth_sock = -1, r;
1492:
1493: if (options.add_keys_to_agent == 0)
1494: return;
1495:
1496: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1497: debug3("no authentication agent, not adding key");
1498: return;
1499: }
1500:
1501: if (options.add_keys_to_agent == 2 &&
1502: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1503: debug3("user denied adding this key");
1.273 dtucker 1504: close(auth_sock);
1.266 jcs 1505: return;
1506: }
1507:
1508: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1509: (options.add_keys_to_agent == 3))) == 0)
1510: debug("identity added to agent: %s", authfile);
1511: else
1512: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1513: close(auth_sock);
1.1 deraadt 1514: }
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