Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.275
1.275 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.274 2017/04/30 23:10:43 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"
1.239 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();
1.275 ! djm 542: int 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:
1.275 ! djm 552: enable_compat20();
! 553: send_client_banner(connection_out, 0);
! 554: client_banner_sent = 1;
1.235 djm 555:
1.163 avsm 556: /* Read other side's version identification. */
1.202 djm 557: remaining = timeout_ms;
1.185 djm 558: for (n = 0;;) {
1.75 markus 559: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 560: if (timeout_ms > 0) {
561: gettimeofday(&t_start, NULL);
562: ms_to_timeval(&t_remaining, remaining);
563: FD_SET(connection_in, fdset);
564: rc = select(connection_in + 1, fdset, NULL,
565: fdset, &t_remaining);
566: ms_subtract_diff(&t_start, &remaining);
567: if (rc == 0 || remaining <= 0)
568: fatal("Connection timed out during "
569: "banner exchange");
570: if (rc == -1) {
571: if (errno == EINTR)
572: continue;
573: fatal("ssh_exchange_identification: "
574: "select: %s", strerror(errno));
575: }
576: }
577:
1.270 markus 578: len = atomicio(read, connection_in, &buf[i], 1);
1.163 avsm 579:
1.167 djm 580: if (len != 1 && errno == EPIPE)
1.202 djm 581: fatal("ssh_exchange_identification: "
582: "Connection closed by remote host");
1.163 avsm 583: else if (len != 1)
1.202 djm 584: fatal("ssh_exchange_identification: "
585: "read: %.100s", strerror(errno));
1.75 markus 586: if (buf[i] == '\r') {
587: buf[i] = '\n';
588: buf[i + 1] = 0;
589: continue; /**XXX wait for \n */
590: }
591: if (buf[i] == '\n') {
592: buf[i + 1] = 0;
593: break;
594: }
1.185 djm 595: if (++n > 65536)
1.202 djm 596: fatal("ssh_exchange_identification: "
597: "No banner received");
1.38 markus 598: }
1.75 markus 599: buf[sizeof(buf) - 1] = 0;
1.76 markus 600: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 601: break;
1.75 markus 602: debug("ssh_exchange_identification: %s", buf);
1.38 markus 603: }
1.59 markus 604: server_version_string = xstrdup(buf);
1.238 djm 605: free(fdset);
1.38 markus 606:
1.40 markus 607: /*
608: * Check that the versions match. In future this might accept
609: * several versions and set appropriate flags to handle them.
610: */
1.59 markus 611: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
612: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 613: fatal("Bad remote protocol version identification: '%.100s'", buf);
614: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 615: remote_major, remote_minor, remote_version);
1.38 markus 616:
1.255 markus 617: active_state->compat = compat_datafellows(remote_version);
1.64 markus 618: mismatch = 0;
1.59 markus 619:
1.116 deraadt 620: switch (remote_major) {
1.64 markus 621: case 1:
1.275 ! djm 622: if (remote_minor == 99)
1.64 markus 623: enable_compat20();
1.275 ! djm 624: else
1.64 markus 625: mismatch = 1;
626: break;
627: case 2:
1.275 ! djm 628: enable_compat20();
! 629: break;
1.68 markus 630: default:
1.64 markus 631: mismatch = 1;
632: break;
1.38 markus 633: }
1.64 markus 634: if (mismatch)
1.38 markus 635: fatal("Protocol major versions differ: %d vs. %d",
1.275 ! djm 636: PROTOCOL_MAJOR_2, remote_major);
1.244 djm 637: if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
638: fatal("Server version \"%.100s\" uses unsafe key agreement; "
639: "refusing connection", remote_version);
1.243 djm 640: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
641: logit("Server version \"%.100s\" uses unsafe RSA signature "
642: "scheme; disabling use of RSA keys", remote_version);
1.59 markus 643: chop(server_version_string);
1.1 deraadt 644: }
645:
1.96 markus 646: /* defaults to 'no' */
1.109 itojun 647: static int
1.112 markus 648: confirm(const char *prompt)
1.1 deraadt 649: {
1.119 markus 650: const char *msg, *again = "Please type 'yes' or 'no': ";
651: char *p;
652: int ret = -1;
1.96 markus 653:
654: if (options.batch_mode)
655: return 0;
1.119 markus 656: for (msg = prompt;;msg = again) {
657: p = read_passphrase(msg, RP_ECHO);
658: if (p == NULL ||
659: (p[0] == '\0') || (p[0] == '\n') ||
660: strncasecmp(p, "no", 2) == 0)
661: ret = 0;
1.127 markus 662: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 663: ret = 1;
1.238 djm 664: free(p);
1.119 markus 665: if (ret != -1)
666: return ret;
1.1 deraadt 667: }
668: }
669:
1.219 djm 670: static int
671: check_host_cert(const char *host, const Key *host_key)
672: {
673: const char *reason;
674:
675: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
676: error("%s", reason);
677: return 0;
678: }
1.249 djm 679: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 680: error("Certificate for %s contains unsupported "
681: "critical options(s)", host);
1.219 djm 682: return 0;
683: }
684: return 1;
685: }
686:
1.229 djm 687: static int
688: sockaddr_is_local(struct sockaddr *hostaddr)
689: {
690: switch (hostaddr->sa_family) {
691: case AF_INET:
692: return (ntohl(((struct sockaddr_in *)hostaddr)->
693: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
694: case AF_INET6:
695: return IN6_IS_ADDR_LOOPBACK(
696: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
697: default:
698: return 0;
699: }
700: }
701:
702: /*
703: * Prepare the hostname and ip address strings that are used to lookup
704: * host keys in known_hosts files. These may have a port number appended.
705: */
706: void
707: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
708: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
709: {
710: char ntop[NI_MAXHOST];
711:
712: /*
713: * We don't have the remote ip-address for connections
714: * using a proxy command
715: */
716: if (hostfile_ipaddr != NULL) {
717: if (options.proxy_command == NULL) {
718: if (getnameinfo(hostaddr, hostaddr->sa_len,
719: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 720: fatal("%s: getnameinfo failed", __func__);
1.229 djm 721: *hostfile_ipaddr = put_host_port(ntop, port);
722: } else {
723: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
724: "command>");
725: }
726: }
727:
728: /*
729: * Allow the user to record the key under a different name or
730: * differentiate a non-standard port. This is useful for ssh
731: * tunneling over forwarded connections or if you run multiple
732: * sshd's on different ports on the same machine.
733: */
734: if (hostfile_hostname != NULL) {
735: if (options.host_key_alias != NULL) {
736: *hostfile_hostname = xstrdup(options.host_key_alias);
737: debug("using hostkeyalias: %s", *hostfile_hostname);
738: } else {
739: *hostfile_hostname = put_host_port(hostname, port);
740: }
741: }
742: }
743:
1.39 deraadt 744: /*
1.108 markus 745: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 746: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 747: */
1.197 dtucker 748: #define RDRW 0
749: #define RDONLY 1
750: #define ROQUIET 2
1.109 itojun 751: static int
1.197 dtucker 752: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.234 djm 753: Key *host_key, int readonly,
754: char **user_hostfiles, u_int num_user_hostfiles,
755: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 756: {
1.234 djm 757: HostStatus host_status;
758: HostStatus ip_status;
1.229 djm 759: Key *raw_key = NULL;
1.189 dtucker 760: char *ip = NULL, *host = NULL;
1.204 grunk 761: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 762: char msg[1024];
1.234 djm 763: const char *type;
764: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 765: int len, cancelled_forwarding = 0;
1.234 djm 766: int local = sockaddr_is_local(hostaddr);
767: int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
1.257 djm 768: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 769: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 770: u_int i;
1.49 markus 771:
772: /*
773: * Force accepting of the host key for loopback/localhost. The
774: * problem is that if the home directory is NFS-mounted to multiple
775: * machines, localhost will refer to a different machine in each of
776: * them, and the user will get bogus HOST_CHANGED warnings. This
777: * essentially disables host authentication for localhost; however,
778: * this is probably not a real problem.
779: */
1.111 markus 780: if (options.no_host_authentication_for_localhost == 1 && local &&
781: options.host_key_alias == NULL) {
1.88 markus 782: debug("Forcing accepting of host key for "
783: "loopback/localhost.");
1.108 markus 784: return 0;
1.49 markus 785: }
1.42 markus 786:
787: /*
1.229 djm 788: * Prepare the hostname and address strings used for hostkey lookup.
789: * In some cases, these will have a port number appended.
1.42 markus 790: */
1.229 djm 791: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 792:
793: /*
1.88 markus 794: * Turn off check_host_ip if the connection is to localhost, via proxy
795: * command or if we don't have a hostname to compare with
796: */
1.189 dtucker 797: if (options.check_host_ip && (local ||
798: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 799: options.check_host_ip = 0;
1.86 markus 800:
1.229 djm 801: host_hostkeys = init_hostkeys();
1.234 djm 802: for (i = 0; i < num_user_hostfiles; i++)
803: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
804: for (i = 0; i < num_system_hostfiles; i++)
805: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 806:
807: ip_hostkeys = NULL;
808: if (!want_cert && options.check_host_ip) {
809: ip_hostkeys = init_hostkeys();
1.234 djm 810: for (i = 0; i < num_user_hostfiles; i++)
811: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
812: for (i = 0; i < num_system_hostfiles; i++)
813: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 814: }
1.38 markus 815:
1.219 djm 816: retry:
1.229 djm 817: /* Reload these as they may have changed on cert->key downgrade */
1.219 djm 818: want_cert = key_is_cert(host_key);
819: type = key_type(host_key);
820:
1.46 markus 821: /*
1.170 djm 822: * Check if the host key is present in the user's list of known
1.40 markus 823: * hosts or in the systemwide list.
824: */
1.229 djm 825: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
826: &host_found);
827:
1.40 markus 828: /*
829: * Also perform check for the ip address, skip the check if we are
1.219 djm 830: * localhost, looking for a certificate, or the hostname was an ip
831: * address to begin with.
1.40 markus 832: */
1.229 djm 833: if (!want_cert && ip_hostkeys != NULL) {
834: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
835: &ip_found);
1.38 markus 836: if (host_status == HOST_CHANGED &&
1.229 djm 837: (ip_status != HOST_CHANGED ||
838: (ip_found != NULL &&
839: !key_equal(ip_found->key, host_found->key))))
1.38 markus 840: host_ip_differ = 1;
841: } else
842: ip_status = host_status;
843:
844: switch (host_status) {
845: case HOST_OK:
846: /* The host is known and the key matches. */
1.219 djm 847: debug("Host '%.200s' is known and matches the %s host %s.",
848: host, type, want_cert ? "certificate" : "key");
1.229 djm 849: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
850: host_found->file, host_found->line);
1.219 djm 851: if (want_cert && !check_host_cert(hostname, host_key))
852: goto fail;
1.88 markus 853: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 854: if (readonly || want_cert)
1.138 itojun 855: logit("%s host key for IP address "
1.108 markus 856: "'%.128s' not in list of known hosts.",
857: type, ip);
1.234 djm 858: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 859: host_key, options.hash_known_hosts))
1.138 itojun 860: logit("Failed to add the %s host key for IP "
1.108 markus 861: "address '%.128s' to the list of known "
1.262 dtucker 862: "hosts (%.500s).", type, ip,
1.234 djm 863: user_hostfiles[0]);
1.88 markus 864: else
1.138 itojun 865: logit("Warning: Permanently added the %s host "
1.108 markus 866: "key for IP address '%.128s' to the list "
867: "of known hosts.", type, ip);
1.209 grunk 868: } else if (options.visual_host_key) {
1.259 djm 869: fp = sshkey_fingerprint(host_key,
1.254 djm 870: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 871: ra = sshkey_fingerprint(host_key,
1.254 djm 872: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 873: if (fp == NULL || ra == NULL)
874: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 875: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 876: free(ra);
877: free(fp);
1.38 markus 878: }
1.257 djm 879: hostkey_trusted = 1;
1.38 markus 880: break;
881: case HOST_NEW:
1.197 dtucker 882: if (options.host_key_alias == NULL && port != 0 &&
883: port != SSH_DEFAULT_PORT) {
884: debug("checking without port identifier");
1.212 stevesk 885: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 886: ROQUIET, user_hostfiles, num_user_hostfiles,
887: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 888: debug("found matching key w/out port");
889: break;
890: }
891: }
1.219 djm 892: if (readonly || want_cert)
1.108 markus 893: goto fail;
1.38 markus 894: /* The host is new. */
895: if (options.strict_host_key_checking == 1) {
1.108 markus 896: /*
897: * User has requested strict host key checking. We
898: * will not add the host key automatically. The only
899: * alternative left is to abort.
900: */
901: error("No %s host key is known for %.200s and you "
902: "have requested strict checking.", type, host);
903: goto fail;
1.38 markus 904: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 905: char msg1[1024], msg2[1024];
906:
1.229 djm 907: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 908: snprintf(msg1, sizeof(msg1),
1.168 djm 909: "\nbut keys of different type are already"
910: " known for this host.");
1.145 jakob 911: else
912: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 913: /* The default */
1.259 djm 914: fp = sshkey_fingerprint(host_key,
1.254 djm 915: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 916: ra = sshkey_fingerprint(host_key,
1.254 djm 917: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 918: if (fp == NULL || ra == NULL)
919: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 920: msg2[0] = '\0';
921: if (options.verify_host_key_dns) {
1.153 jakob 922: if (matching_host_key_dns)
1.145 jakob 923: snprintf(msg2, sizeof(msg2),
924: "Matching host key fingerprint"
925: " found in DNS.\n");
926: else
927: snprintf(msg2, sizeof(msg2),
928: "No matching host key fingerprint"
929: " found in DNS.\n");
930: }
1.119 markus 931: snprintf(msg, sizeof(msg),
1.108 markus 932: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 933: "established%s\n"
1.209 grunk 934: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 935: "Are you sure you want to continue connecting "
1.132 markus 936: "(yes/no)? ",
1.209 grunk 937: host, ip, msg1, type, fp,
938: options.visual_host_key ? "\n" : "",
939: options.visual_host_key ? ra : "",
940: msg2);
1.238 djm 941: free(ra);
942: free(fp);
1.119 markus 943: if (!confirm(msg))
1.108 markus 944: goto fail;
1.257 djm 945: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 946: }
1.161 djm 947: /*
948: * If not in strict mode, add the key automatically to the
949: * local known_hosts file.
950: */
1.88 markus 951: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 952: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 953: hostp = hostline;
1.161 djm 954: if (options.hash_known_hosts) {
955: /* Add hash of host and IP separately */
1.234 djm 956: r = add_host_to_hostfile(user_hostfiles[0],
957: host, host_key, options.hash_known_hosts) &&
958: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 959: host_key, options.hash_known_hosts);
960: } else {
961: /* Add unhashed "host,ip" */
1.234 djm 962: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 963: hostline, host_key,
964: options.hash_known_hosts);
965: }
966: } else {
1.234 djm 967: r = add_host_to_hostfile(user_hostfiles[0], host,
968: host_key, options.hash_known_hosts);
1.38 markus 969: hostp = host;
1.161 djm 970: }
1.38 markus 971:
1.161 djm 972: if (!r)
1.138 itojun 973: logit("Failed to add the host to the list of known "
1.234 djm 974: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 975: else
1.138 itojun 976: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 977: "list of known hosts.", hostp, type);
1.38 markus 978: break;
1.220 djm 979: case HOST_REVOKED:
980: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
981: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
982: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
983: error("The %s host key for %s is marked as revoked.", type, host);
984: error("This could mean that a stolen key is being used to");
985: error("impersonate this host.");
986:
987: /*
988: * If strict host key checking is in use, the user will have
989: * to edit the key manually and we can only abort.
990: */
991: if (options.strict_host_key_checking) {
992: error("%s host key for %.200s was revoked and you have "
993: "requested strict checking.", type, host);
994: goto fail;
995: }
996: goto continue_unsafe;
997:
1.38 markus 998: case HOST_CHANGED:
1.219 djm 999: if (want_cert) {
1000: /*
1001: * This is only a debug() since it is valid to have
1002: * CAs with wildcard DNS matches that don't match
1003: * all hosts that one might visit.
1004: */
1005: debug("Host certificate authority does not "
1.229 djm 1006: "match %s in %s:%lu", CA_MARKER,
1007: host_found->file, host_found->line);
1.219 djm 1008: goto fail;
1009: }
1.197 dtucker 1010: if (readonly == ROQUIET)
1011: goto fail;
1.38 markus 1012: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1013: char *key_msg;
1.38 markus 1014: if (ip_status == HOST_NEW)
1.158 avsm 1015: key_msg = "is unknown";
1.38 markus 1016: else if (ip_status == HOST_OK)
1.158 avsm 1017: key_msg = "is unchanged";
1.38 markus 1018: else
1.158 avsm 1019: key_msg = "has a different value";
1.38 markus 1020: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1021: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1022: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1023: error("The %s host key for %s has changed,", type, host);
1.208 ian 1024: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1025: error("%s. This could either mean that", key_msg);
1.38 markus 1026: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1027: error("and its host key have changed at the same time.");
1.88 markus 1028: if (ip_status != HOST_NEW)
1.229 djm 1029: error("Offending key for IP in %s:%lu",
1030: ip_found->file, ip_found->line);
1.38 markus 1031: }
1032: /* The host key has changed. */
1.150 jakob 1033: warn_changed_key(host_key);
1.38 markus 1034: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1035: user_hostfiles[0]);
1.229 djm 1036: error("Offending %s key in %s:%lu", key_type(host_found->key),
1037: host_found->file, host_found->line);
1.38 markus 1038:
1.40 markus 1039: /*
1040: * If strict host key checking is in use, the user will have
1041: * to edit the key manually and we can only abort.
1042: */
1.108 markus 1043: if (options.strict_host_key_checking) {
1044: error("%s host key for %.200s has changed and you have "
1045: "requested strict checking.", type, host);
1046: goto fail;
1047: }
1.38 markus 1048:
1.220 djm 1049: continue_unsafe:
1.40 markus 1050: /*
1051: * If strict host key checking has not been requested, allow
1.144 djm 1052: * the connection but without MITM-able authentication or
1.194 stevesk 1053: * forwarding.
1.40 markus 1054: */
1.38 markus 1055: if (options.password_authentication) {
1.108 markus 1056: error("Password authentication is disabled to avoid "
1057: "man-in-the-middle attacks.");
1.38 markus 1058: options.password_authentication = 0;
1.210 dtucker 1059: cancelled_forwarding = 1;
1.144 djm 1060: }
1061: if (options.kbd_interactive_authentication) {
1062: error("Keyboard-interactive authentication is disabled"
1063: " to avoid man-in-the-middle attacks.");
1064: options.kbd_interactive_authentication = 0;
1065: options.challenge_response_authentication = 0;
1.210 dtucker 1066: cancelled_forwarding = 1;
1.144 djm 1067: }
1068: if (options.challenge_response_authentication) {
1069: error("Challenge/response authentication is disabled"
1070: " to avoid man-in-the-middle attacks.");
1071: options.challenge_response_authentication = 0;
1.210 dtucker 1072: cancelled_forwarding = 1;
1.38 markus 1073: }
1074: if (options.forward_agent) {
1.108 markus 1075: error("Agent forwarding is disabled to avoid "
1076: "man-in-the-middle attacks.");
1.38 markus 1077: options.forward_agent = 0;
1.210 dtucker 1078: cancelled_forwarding = 1;
1.83 markus 1079: }
1080: if (options.forward_x11) {
1.108 markus 1081: error("X11 forwarding is disabled to avoid "
1082: "man-in-the-middle attacks.");
1.83 markus 1083: options.forward_x11 = 0;
1.210 dtucker 1084: cancelled_forwarding = 1;
1.83 markus 1085: }
1.108 markus 1086: if (options.num_local_forwards > 0 ||
1087: options.num_remote_forwards > 0) {
1088: error("Port forwarding is disabled to avoid "
1089: "man-in-the-middle attacks.");
1090: options.num_local_forwards =
1.118 deraadt 1091: options.num_remote_forwards = 0;
1.210 dtucker 1092: cancelled_forwarding = 1;
1.194 stevesk 1093: }
1094: if (options.tun_open != SSH_TUNMODE_NO) {
1095: error("Tunnel forwarding is disabled to avoid "
1096: "man-in-the-middle attacks.");
1097: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1098: cancelled_forwarding = 1;
1.38 markus 1099: }
1.210 dtucker 1100: if (options.exit_on_forward_failure && cancelled_forwarding)
1101: fatal("Error: forwarding disabled due to host key "
1102: "check failure");
1103:
1.40 markus 1104: /*
1105: * XXX Should permit the user to change to use the new id.
1106: * This could be done by converting the host key to an
1107: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1108: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1109: * accept the authentication.
1110: */
1.38 markus 1111: break;
1.132 markus 1112: case HOST_FOUND:
1113: fatal("internal error");
1114: break;
1.88 markus 1115: }
1116:
1117: if (options.check_host_ip && host_status != HOST_CHANGED &&
1118: ip_status == HOST_CHANGED) {
1.119 markus 1119: snprintf(msg, sizeof(msg),
1120: "Warning: the %s host key for '%.200s' "
1121: "differs from the key for the IP address '%.128s'"
1.229 djm 1122: "\nOffending key for IP in %s:%lu",
1123: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1124: if (host_status == HOST_OK) {
1125: len = strlen(msg);
1126: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1127: "\nMatching host key in %s:%lu",
1128: host_found->file, host_found->line);
1.119 markus 1129: }
1.88 markus 1130: if (options.strict_host_key_checking == 1) {
1.143 djm 1131: logit("%s", msg);
1.108 markus 1132: error("Exiting, you have requested strict checking.");
1133: goto fail;
1.88 markus 1134: } else if (options.strict_host_key_checking == 2) {
1.119 markus 1135: strlcat(msg, "\nAre you sure you want "
1136: "to continue connecting (yes/no)? ", sizeof(msg));
1137: if (!confirm(msg))
1.108 markus 1138: goto fail;
1.119 markus 1139: } else {
1.143 djm 1140: logit("%s", msg);
1.88 markus 1141: }
1.257 djm 1142: }
1143:
1144: if (!hostkey_trusted && options.update_hostkeys) {
1145: debug("%s: hostkey not known or explicitly trusted: "
1146: "disabling UpdateHostkeys", __func__);
1147: options.update_hostkeys = 0;
1.38 markus 1148: }
1.82 provos 1149:
1.238 djm 1150: free(ip);
1151: free(host);
1.229 djm 1152: if (host_hostkeys != NULL)
1153: free_hostkeys(host_hostkeys);
1154: if (ip_hostkeys != NULL)
1155: free_hostkeys(ip_hostkeys);
1.108 markus 1156: return 0;
1157:
1158: fail:
1.220 djm 1159: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1160: /*
1161: * No matching certificate. Downgrade cert to raw key and
1162: * search normally.
1163: */
1164: debug("No matching CA found. Retry with plain key");
1165: raw_key = key_from_private(host_key);
1166: if (key_drop_cert(raw_key) != 0)
1167: fatal("Couldn't drop certificate");
1168: host_key = raw_key;
1169: goto retry;
1170: }
1171: if (raw_key != NULL)
1172: key_free(raw_key);
1.238 djm 1173: free(ip);
1174: free(host);
1.229 djm 1175: if (host_hostkeys != NULL)
1176: free_hostkeys(host_hostkeys);
1177: if (ip_hostkeys != NULL)
1178: free_hostkeys(ip_hostkeys);
1.108 markus 1179: return -1;
1180: }
1181:
1.140 jakob 1182: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1183: int
1184: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1185: {
1.267 djm 1186: u_int i;
1.250 djm 1187: int r = -1, flags = 0;
1.267 djm 1188: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1189: struct sshkey *plain = NULL;
1.229 djm 1190:
1.252 djm 1191: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1192: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1193: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1194: r = -1;
1195: goto out;
1196: }
1197:
1.267 djm 1198: if (sshkey_is_cert(host_key)) {
1199: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1200: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1201: error("%s: fingerprint CA key: %s",
1202: __func__, ssh_err(r));
1203: r = -1;
1204: goto out;
1205: }
1206: sshkey_format_cert_validity(host_key->cert,
1207: valid, sizeof(valid));
1208: debug("Server host certificate: %s %s, serial %llu "
1209: "ID \"%s\" CA %s %s valid %s",
1210: sshkey_ssh_name(host_key), fp,
1.269 djm 1211: (unsigned long long)host_key->cert->serial,
1212: host_key->cert->key_id,
1.267 djm 1213: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1214: valid);
1215: for (i = 0; i < host_key->cert->nprincipals; i++) {
1216: debug2("Server host certificate hostname: %s",
1217: host_key->cert->principals[i]);
1218: }
1219: } else {
1220: debug("Server host key: %s %s", compat20 ?
1221: sshkey_ssh_name(host_key) : sshkey_type(host_key), fp);
1222: }
1.252 djm 1223:
1224: if (sshkey_equal(previous_host_key, host_key)) {
1225: debug2("%s: server host key %s %s matches cached key",
1226: __func__, sshkey_type(host_key), fp);
1227: r = 0;
1228: goto out;
1229: }
1230:
1231: /* Check in RevokedHostKeys file if specified */
1232: if (options.revoked_host_keys != NULL) {
1233: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1234: switch (r) {
1235: case 0:
1236: break; /* not revoked */
1237: case SSH_ERR_KEY_REVOKED:
1238: error("Host key %s %s revoked by file %s",
1239: sshkey_type(host_key), fp,
1240: options.revoked_host_keys);
1241: r = -1;
1242: goto out;
1243: default:
1244: error("Error checking host key %s %s in "
1245: "revoked keys file %s: %s", sshkey_type(host_key),
1246: fp, options.revoked_host_keys, ssh_err(r));
1247: r = -1;
1248: goto out;
1249: }
1.250 djm 1250: }
1251:
1.247 djm 1252: if (options.verify_host_key_dns) {
1253: /*
1254: * XXX certs are not yet supported for DNS, so downgrade
1255: * them and try the plain key.
1256: */
1.252 djm 1257: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1258: goto out;
1259: if (sshkey_is_cert(plain))
1260: sshkey_drop_cert(plain);
1.247 djm 1261: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1262: if (flags & DNS_VERIFY_FOUND) {
1263: if (options.verify_host_key_dns == 1 &&
1264: flags & DNS_VERIFY_MATCH &&
1265: flags & DNS_VERIFY_SECURE) {
1.250 djm 1266: r = 0;
1.252 djm 1267: goto out;
1.247 djm 1268: }
1269: if (flags & DNS_VERIFY_MATCH) {
1270: matching_host_key_dns = 1;
1271: } else {
1272: warn_changed_key(plain);
1273: error("Update the SSHFP RR in DNS "
1274: "with the new host key to get rid "
1275: "of this message.");
1276: }
1.153 jakob 1277: }
1.140 jakob 1278: }
1279: }
1.250 djm 1280: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1281: options.user_hostfiles, options.num_user_hostfiles,
1282: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1283:
1.252 djm 1284: out:
1285: sshkey_free(plain);
1286: free(fp);
1.267 djm 1287: free(cafp);
1.250 djm 1288: if (r == 0 && host_key != NULL) {
1289: key_free(previous_host_key);
1290: previous_host_key = key_from_private(host_key);
1291: }
1292:
1293: return r;
1.51 markus 1294: }
1.70 markus 1295:
1.51 markus 1296: /*
1297: * Starts a dialog with the server, and authenticates the current user on the
1298: * server. This does not need any extra privileges. The basic connection
1299: * to the server must already have been established before this is called.
1300: * If login fails, this function prints an error and never returns.
1301: * This function does not require super-user privileges.
1302: */
1303: void
1.120 markus 1304: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1305: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1306: {
1.241 djm 1307: char *host;
1.70 markus 1308: char *server_user, *local_user;
1309:
1310: local_user = xstrdup(pw->pw_name);
1311: server_user = options.user ? options.user : local_user;
1.51 markus 1312:
1313: /* Convert the user-supplied hostname into all lowercase. */
1314: host = xstrdup(orighost);
1.241 djm 1315: lowercase(host);
1.51 markus 1316:
1317: /* Exchange protocol version identification strings with the server. */
1.202 djm 1318: ssh_exchange_identification(timeout_ms);
1.51 markus 1319:
1320: /* Put the connection into non-blocking mode. */
1321: packet_set_nonblocking();
1322:
1323: /* key exchange */
1324: /* authenticate user */
1.261 dtucker 1325: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.59 markus 1326: if (compat20) {
1.229 djm 1327: ssh_kex2(host, hostaddr, port);
1.120 markus 1328: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 1329: } else {
1.260 djm 1330: fatal("ssh1 is not supported");
1.59 markus 1331: }
1.238 djm 1332: free(local_user);
1.97 markus 1333: }
1334:
1335: void
1336: ssh_put_password(char *password)
1337: {
1338: int size;
1339: char *padded;
1340:
1.99 deraadt 1341: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1342: packet_put_cstring(password);
1.99 deraadt 1343: return;
1344: }
1.272 deraadt 1345: size = ROUNDUP(strlen(password) + 1, 32);
1.179 djm 1346: padded = xcalloc(1, size);
1.97 markus 1347: strlcpy(padded, password, size);
1348: packet_put_string(padded, size);
1.245 djm 1349: explicit_bzero(padded, size);
1.238 djm 1350: free(padded);
1.132 markus 1351: }
1352:
1353: /* print all known host keys for a given host, but skip keys of given type */
1354: static int
1.229 djm 1355: show_other_keys(struct hostkeys *hostkeys, Key *key)
1.132 markus 1356: {
1.242 djm 1357: int type[] = {
1358: KEY_RSA1,
1359: KEY_RSA,
1360: KEY_DSA,
1361: KEY_ECDSA,
1362: KEY_ED25519,
1363: -1
1364: };
1.229 djm 1365: int i, ret = 0;
1366: char *fp, *ra;
1367: const struct hostkey_entry *found;
1.132 markus 1368:
1369: for (i = 0; type[i] != -1; i++) {
1370: if (type[i] == key->type)
1371: continue;
1.229 djm 1372: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1373: continue;
1.259 djm 1374: fp = sshkey_fingerprint(found->key,
1.254 djm 1375: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1376: ra = sshkey_fingerprint(found->key,
1.254 djm 1377: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1378: if (fp == NULL || ra == NULL)
1379: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1380: logit("WARNING: %s key found for host %s\n"
1381: "in %s:%lu\n"
1382: "%s key fingerprint %s.",
1383: key_type(found->key),
1384: found->host, found->file, found->line,
1385: key_type(found->key), fp);
1386: if (options.visual_host_key)
1387: logit("%s", ra);
1.238 djm 1388: free(ra);
1389: free(fp);
1.229 djm 1390: ret = 1;
1.132 markus 1391: }
1.229 djm 1392: return ret;
1.150 jakob 1393: }
1394:
1395: static void
1396: warn_changed_key(Key *host_key)
1397: {
1398: char *fp;
1399:
1.259 djm 1400: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1401: SSH_FP_DEFAULT);
1.259 djm 1402: if (fp == NULL)
1403: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1404:
1405: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1406: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1407: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1408: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1409: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1410: error("It is also possible that a host key has just been changed.");
1.150 jakob 1411: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.230 markus 1412: key_type(host_key), fp);
1.150 jakob 1413: error("Please contact your system administrator.");
1414:
1.238 djm 1415: free(fp);
1.171 reyk 1416: }
1417:
1418: /*
1419: * Execute a local command
1420: */
1421: int
1422: ssh_local_cmd(const char *args)
1423: {
1424: char *shell;
1425: pid_t pid;
1426: int status;
1.231 djm 1427: void (*osighand)(int);
1.171 reyk 1428:
1429: if (!options.permit_local_command ||
1430: args == NULL || !*args)
1431: return (1);
1432:
1.226 djm 1433: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1434: shell = _PATH_BSHELL;
1435:
1.231 djm 1436: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1437: pid = fork();
1438: if (pid == 0) {
1.232 djm 1439: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1440: debug3("Executing %s -c \"%s\"", shell, args);
1441: execl(shell, shell, "-c", args, (char *)NULL);
1442: error("Couldn't execute %s -c \"%s\": %s",
1443: shell, args, strerror(errno));
1444: _exit(1);
1445: } else if (pid == -1)
1446: fatal("fork failed: %.100s", strerror(errno));
1447: while (waitpid(pid, &status, 0) == -1)
1448: if (errno != EINTR)
1449: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1450: signal(SIGCHLD, osighand);
1.171 reyk 1451:
1452: if (!WIFEXITED(status))
1453: return (1);
1454:
1455: return (WEXITSTATUS(status));
1.266 jcs 1456: }
1457:
1458: void
1459: maybe_add_key_to_agent(char *authfile, Key *private, char *comment,
1460: char *passphrase)
1461: {
1462: int auth_sock = -1, r;
1463:
1464: if (options.add_keys_to_agent == 0)
1465: return;
1466:
1467: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1468: debug3("no authentication agent, not adding key");
1469: return;
1470: }
1471:
1472: if (options.add_keys_to_agent == 2 &&
1473: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1474: debug3("user denied adding this key");
1.273 dtucker 1475: close(auth_sock);
1.266 jcs 1476: return;
1477: }
1478:
1479: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1480: (options.add_keys_to_agent == 3))) == 0)
1481: debug("identity added to agent: %s", authfile);
1482: else
1483: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1484: close(auth_sock);
1.1 deraadt 1485: }
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