Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.306
1.306 ! florian 1: /* $OpenBSD: sshconnect.c,v 1.305 2018/09/20 03:30:44 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:
1.295 djm 22: #include <net/if.h>
1.187 stevesk 23: #include <netinet/in.h>
1.172 stevesk 24:
1.176 stevesk 25: #include <ctype.h>
1.190 stevesk 26: #include <errno.h>
1.216 dtucker 27: #include <fcntl.h>
1.191 stevesk 28: #include <netdb.h>
1.172 stevesk 29: #include <paths.h>
1.282 djm 30: #include <poll.h>
1.199 deraadt 31: #include <signal.h>
1.188 stevesk 32: #include <pwd.h>
1.198 stevesk 33: #include <stdio.h>
1.196 stevesk 34: #include <stdlib.h>
1.193 stevesk 35: #include <string.h>
1.192 stevesk 36: #include <unistd.h>
1.295 djm 37: #include <ifaddrs.h>
1.71 markus 38:
1.199 deraadt 39: #include "xmalloc.h"
1.91 markus 40: #include "ssh.h"
1.299 markus 41: #include "sshbuf.h"
1.1 deraadt 42: #include "packet.h"
1.21 markus 43: #include "compat.h"
1.300 markus 44: #include "sshkey.h"
1.71 markus 45: #include "sshconnect.h"
1.58 markus 46: #include "hostfile.h"
1.91 markus 47: #include "log.h"
1.251 millert 48: #include "misc.h"
1.91 markus 49: #include "readconf.h"
50: #include "atomicio.h"
1.140 jakob 51: #include "dns.h"
1.239 djm 52: #include "monitor_fdpass.h"
1.219 djm 53: #include "ssh2.h"
1.186 stevesk 54: #include "version.h"
1.252 djm 55: #include "authfile.h"
56: #include "ssherr.h"
1.266 jcs 57: #include "authfd.h"
1.140 jakob 58:
1.70 markus 59: char *client_version_string = NULL;
60: char *server_version_string = NULL;
1.279 markus 61: struct sshkey *previous_host_key = NULL;
1.59 markus 62:
1.169 stevesk 63: static int matching_host_key_dns = 0;
1.145 jakob 64:
1.227 djm 65: static pid_t proxy_command_pid = 0;
66:
1.124 markus 67: /* import */
1.43 markus 68: extern Options options;
1.50 markus 69: extern char *__progname;
1.91 markus 70:
1.279 markus 71: static int show_other_keys(struct hostkeys *, struct sshkey *);
72: static void warn_changed_key(struct sshkey *);
1.132 markus 73:
1.239 djm 74: /* Expand a proxy command */
75: static char *
76: expand_proxy_command(const char *proxy_command, const char *user,
77: const char *host, int port)
78: {
79: char *tmp, *ret, strport[NI_MAXSERV];
80:
1.241 djm 81: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 82: xasprintf(&tmp, "exec %s", proxy_command);
83: ret = percent_expand(tmp, "h", host, "p", strport,
84: "r", options.user, (char *)NULL);
85: free(tmp);
86: return ret;
87: }
88:
89: /*
90: * Connect to the given ssh server using a proxy command that passes a
91: * a connected fd back to us.
92: */
93: static int
1.286 djm 94: ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, u_short port,
1.239 djm 95: const char *proxy_command)
96: {
97: char *command_string;
98: int sp[2], sock;
99: pid_t pid;
100: char *shell;
101:
102: if ((shell = getenv("SHELL")) == NULL)
103: shell = _PATH_BSHELL;
104:
105: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
106: fatal("Could not create socketpair to communicate with "
107: "proxy dialer: %.100s", strerror(errno));
108:
109: command_string = expand_proxy_command(proxy_command, options.user,
110: host, port);
111: debug("Executing proxy dialer command: %.500s", command_string);
112:
113: /* Fork and execute the proxy command. */
114: if ((pid = fork()) == 0) {
115: char *argv[10];
116:
117: close(sp[1]);
118: /* Redirect stdin and stdout. */
119: if (sp[0] != 0) {
120: if (dup2(sp[0], 0) < 0)
121: perror("dup2 stdin");
122: }
123: if (sp[0] != 1) {
124: if (dup2(sp[0], 1) < 0)
125: perror("dup2 stdout");
126: }
127: if (sp[0] >= 2)
128: close(sp[0]);
129:
130: /*
131: * Stderr is left as it is so that error messages get
132: * printed on the user's terminal.
133: */
134: argv[0] = shell;
135: argv[1] = "-c";
136: argv[2] = command_string;
137: argv[3] = NULL;
138:
139: /*
140: * Execute the proxy command.
141: * Note that we gave up any extra privileges above.
142: */
143: execv(argv[0], argv);
144: perror(argv[0]);
145: exit(1);
146: }
147: /* Parent. */
148: if (pid < 0)
149: fatal("fork failed: %.100s", strerror(errno));
150: close(sp[0]);
151: free(command_string);
152:
153: if ((sock = mm_receive_fd(sp[1])) == -1)
154: fatal("proxy dialer did not pass back a connection");
1.271 markus 155: close(sp[1]);
1.239 djm 156:
157: while (waitpid(pid, NULL, 0) == -1)
158: if (errno != EINTR)
159: fatal("Couldn't wait for child: %s", strerror(errno));
160:
161: /* Set the connection file descriptors. */
1.286 djm 162: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
163: return -1; /* ssh_packet_set_connection logs error */
1.239 djm 164:
165: return 0;
166: }
167:
1.39 deraadt 168: /*
169: * Connect to the given ssh server using a proxy command.
170: */
1.109 itojun 171: static int
1.286 djm 172: ssh_proxy_connect(struct ssh *ssh, const char *host, u_short port,
173: const char *proxy_command)
1.1 deraadt 174: {
1.239 djm 175: char *command_string;
1.38 markus 176: int pin[2], pout[2];
1.69 deraadt 177: pid_t pid;
1.239 djm 178: char *shell;
1.237 markus 179:
1.226 djm 180: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 181: shell = _PATH_BSHELL;
1.38 markus 182:
183: /* Create pipes for communicating with the proxy. */
184: if (pipe(pin) < 0 || pipe(pout) < 0)
185: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 186: strerror(errno));
1.38 markus 187:
1.239 djm 188: command_string = expand_proxy_command(proxy_command, options.user,
189: host, port);
1.38 markus 190: debug("Executing proxy command: %.500s", command_string);
191:
192: /* Fork and execute the proxy command. */
193: if ((pid = fork()) == 0) {
194: char *argv[10];
195:
196: /* Redirect stdin and stdout. */
197: close(pin[1]);
198: if (pin[0] != 0) {
199: if (dup2(pin[0], 0) < 0)
200: perror("dup2 stdin");
201: close(pin[0]);
202: }
203: close(pout[0]);
204: if (dup2(pout[1], 1) < 0)
205: perror("dup2 stdout");
206: /* Cannot be 1 because pin allocated two descriptors. */
207: close(pout[1]);
208:
209: /* Stderr is left as it is so that error messages get
210: printed on the user's terminal. */
1.201 djm 211: argv[0] = shell;
1.38 markus 212: argv[1] = "-c";
213: argv[2] = command_string;
214: argv[3] = NULL;
215:
216: /* Execute the proxy command. Note that we gave up any
217: extra privileges above. */
1.232 djm 218: signal(SIGPIPE, SIG_DFL);
1.89 markus 219: execv(argv[0], argv);
220: perror(argv[0]);
1.38 markus 221: exit(1);
222: }
223: /* Parent. */
224: if (pid < 0)
225: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 226: else
227: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 228:
229: /* Close child side of the descriptors. */
230: close(pin[0]);
231: close(pout[1]);
232:
233: /* Free the command name. */
1.238 djm 234: free(command_string);
1.38 markus 235:
236: /* Set the connection file descriptors. */
1.286 djm 237: if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
238: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 239:
1.110 markus 240: return 0;
1.227 djm 241: }
242:
243: void
244: ssh_kill_proxy_command(void)
245: {
246: /*
247: * Send SIGHUP to proxy command if used. We don't wait() in
248: * case it hangs and instead rely on init to reap the child
249: */
250: if (proxy_command_pid > 1)
1.228 djm 251: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 252: }
253:
1.39 deraadt 254: /*
1.295 djm 255: * Search a interface address list (returned from getifaddrs(3)) for an
1.298 djm 256: * address that matches the desired address family on the specified interface.
1.295 djm 257: * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure.
258: */
259: static int
260: check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs,
261: struct sockaddr_storage *resultp, socklen_t *rlenp)
262: {
263: struct sockaddr_in6 *sa6;
264: struct sockaddr_in *sa;
265: struct in6_addr *v6addr;
266: const struct ifaddrs *ifa;
267: int allow_local;
268:
269: /*
270: * Prefer addresses that are not loopback or linklocal, but use them
271: * if nothing else matches.
272: */
273: for (allow_local = 0; allow_local < 2; allow_local++) {
274: for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
275: if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL ||
276: (ifa->ifa_flags & IFF_UP) == 0 ||
277: ifa->ifa_addr->sa_family != af ||
278: strcmp(ifa->ifa_name, options.bind_interface) != 0)
279: continue;
280: switch (ifa->ifa_addr->sa_family) {
281: case AF_INET:
282: sa = (struct sockaddr_in *)ifa->ifa_addr;
283: if (!allow_local && sa->sin_addr.s_addr ==
284: htonl(INADDR_LOOPBACK))
285: continue;
286: if (*rlenp < sizeof(struct sockaddr_in)) {
287: error("%s: v4 addr doesn't fit",
288: __func__);
289: return -1;
290: }
291: *rlenp = sizeof(struct sockaddr_in);
292: memcpy(resultp, sa, *rlenp);
293: return 0;
294: case AF_INET6:
295: sa6 = (struct sockaddr_in6 *)ifa->ifa_addr;
296: v6addr = &sa6->sin6_addr;
297: if (!allow_local &&
298: (IN6_IS_ADDR_LINKLOCAL(v6addr) ||
299: IN6_IS_ADDR_LOOPBACK(v6addr)))
300: continue;
301: if (*rlenp < sizeof(struct sockaddr_in6)) {
302: error("%s: v6 addr doesn't fit",
303: __func__);
304: return -1;
305: }
306: *rlenp = sizeof(struct sockaddr_in6);
307: memcpy(resultp, sa6, *rlenp);
308: return 0;
309: }
310: }
311: }
312: return -1;
313: }
314:
315: /*
1.303 dtucker 316: * Creates a socket for use as the ssh connection.
1.39 deraadt 317: */
1.109 itojun 318: static int
1.302 dtucker 319: ssh_create_socket(struct addrinfo *ai)
1.1 deraadt 320: {
1.301 dtucker 321: int sock, r;
1.295 djm 322: struct sockaddr_storage bindaddr;
323: socklen_t bindaddrlen = 0;
1.246 djm 324: struct addrinfo hints, *res = NULL;
1.295 djm 325: struct ifaddrs *ifaddrs = NULL;
326: char ntop[NI_MAXHOST];
1.1 deraadt 327:
1.217 dtucker 328: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 329: if (sock < 0) {
1.240 djm 330: error("socket: %s", strerror(errno));
1.216 dtucker 331: return -1;
332: }
333: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 334:
335: /* Bind the socket to an alternative local IP address */
1.302 dtucker 336: if (options.bind_address == NULL && options.bind_interface == NULL)
1.105 markus 337: return sock;
338:
1.295 djm 339: if (options.bind_address != NULL) {
1.246 djm 340: memset(&hints, 0, sizeof(hints));
341: hints.ai_family = ai->ai_family;
342: hints.ai_socktype = ai->ai_socktype;
343: hints.ai_protocol = ai->ai_protocol;
344: hints.ai_flags = AI_PASSIVE;
1.295 djm 345: if ((r = getaddrinfo(options.bind_address, NULL,
346: &hints, &res)) != 0) {
1.246 djm 347: error("getaddrinfo: %s: %s", options.bind_address,
1.295 djm 348: ssh_gai_strerror(r));
349: goto fail;
350: }
1.296 dtucker 351: if (res == NULL) {
1.295 djm 352: error("getaddrinfo: no addrs");
353: goto fail;
354: }
355: memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
356: bindaddrlen = res->ai_addrlen;
357: } else if (options.bind_interface != NULL) {
358: if ((r = getifaddrs(&ifaddrs)) != 0) {
359: error("getifaddrs: %s: %s", options.bind_interface,
360: strerror(errno));
361: goto fail;
362: }
363: bindaddrlen = sizeof(bindaddr);
364: if (check_ifaddrs(options.bind_interface, ai->ai_family,
365: ifaddrs, &bindaddr, &bindaddrlen) != 0) {
366: logit("getifaddrs: %s: no suitable addresses",
367: options.bind_interface);
368: goto fail;
1.246 djm 369: }
1.105 markus 370: }
1.295 djm 371: if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
372: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
373: error("%s: getnameinfo failed: %s", __func__,
374: ssh_gai_strerror(r));
375: goto fail;
376: }
1.301 dtucker 377: if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
1.295 djm 378: error("bind %s: %s", ntop, strerror(errno));
379: goto fail;
1.38 markus 380: }
1.295 djm 381: debug("%s: bound to %s", __func__, ntop);
382: /* success */
383: goto out;
384: fail:
385: close(sock);
386: sock = -1;
387: out:
1.246 djm 388: if (res != NULL)
389: freeaddrinfo(res);
1.295 djm 390: if (ifaddrs != NULL)
391: freeifaddrs(ifaddrs);
1.38 markus 392: return sock;
1.1 deraadt 393: }
394:
1.282 djm 395: /*
396: * Wait up to *timeoutp milliseconds for fd to be readable. Updates
397: * *timeoutp with time remaining.
398: * Returns 0 if fd ready or -1 on timeout or error (see errno).
399: */
400: static int
401: waitrfd(int fd, int *timeoutp)
402: {
403: struct pollfd pfd;
404: struct timeval t_start;
405: int oerrno, r;
406:
1.288 dtucker 407: monotime_tv(&t_start);
1.282 djm 408: pfd.fd = fd;
409: pfd.events = POLLIN;
410: for (; *timeoutp >= 0;) {
411: r = poll(&pfd, 1, *timeoutp);
412: oerrno = errno;
413: ms_subtract_diff(&t_start, timeoutp);
414: errno = oerrno;
415: if (r > 0)
416: return 0;
417: else if (r == -1 && errno != EAGAIN)
418: return -1;
419: else if (r == 0)
420: break;
421: }
422: /* timeout */
423: errno = ETIMEDOUT;
424: return -1;
425: }
426:
1.141 djm 427: static int
428: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 429: socklen_t addrlen, int *timeoutp)
1.141 djm 430: {
1.282 djm 431: int optval = 0;
432: socklen_t optlen = sizeof(optval);
1.141 djm 433:
1.282 djm 434: /* No timeout: just do a blocking connect() */
435: if (*timeoutp <= 0)
436: return connect(sockfd, serv_addr, addrlen);
1.141 djm 437:
1.156 djm 438: set_nonblock(sockfd);
1.282 djm 439: if (connect(sockfd, serv_addr, addrlen) == 0) {
440: /* Succeeded already? */
1.156 djm 441: unset_nonblock(sockfd);
1.282 djm 442: return 0;
443: } else if (errno != EINPROGRESS)
444: return -1;
445:
446: if (waitrfd(sockfd, timeoutp) == -1)
447: return -1;
1.141 djm 448:
1.282 djm 449: /* Completed or failed */
450: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, &optlen) == -1) {
451: debug("getsockopt: %s", strerror(errno));
452: return -1;
1.141 djm 453: }
1.282 djm 454: if (optval != 0) {
455: errno = optval;
456: return -1;
1.202 djm 457: }
1.282 djm 458: unset_nonblock(sockfd);
459: return 0;
1.141 djm 460: }
461:
1.39 deraadt 462: /*
1.49 markus 463: * Opens a TCP/IP connection to the remote server on the given host.
464: * The address of the remote host will be returned in hostaddr.
1.302 dtucker 465: * If port is 0, the default port will be used.
1.39 deraadt 466: * Connection_attempts specifies the maximum number of tries (one per
467: * second). If proxy_command is non-NULL, it specifies the command (with %h
468: * and %p substituted for host and port, respectively) to use to contact
469: * the daemon.
470: */
1.241 djm 471: static int
1.286 djm 472: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.241 djm 473: struct sockaddr_storage *hostaddr, u_short port, int family,
1.302 dtucker 474: int connection_attempts, int *timeout_ms, int want_keepalive)
1.1 deraadt 475: {
1.90 markus 476: int on = 1;
1.290 djm 477: int oerrno, sock = -1, attempt;
1.90 markus 478: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 479: struct addrinfo *ai;
1.38 markus 480:
1.302 dtucker 481: debug2("%s", __func__);
1.268 djm 482: memset(ntop, 0, sizeof(ntop));
483: memset(strport, 0, sizeof(strport));
1.38 markus 484:
1.181 markus 485: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 486: if (attempt > 0) {
487: /* Sleep a moment before retrying. */
488: sleep(1);
1.38 markus 489: debug("Trying again...");
1.200 markus 490: }
1.181 markus 491: /*
492: * Loop through addresses for this host, and try each one in
493: * sequence until the connection succeeds.
494: */
1.49 markus 495: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 496: if (ai->ai_family != AF_INET &&
1.290 djm 497: ai->ai_family != AF_INET6) {
498: errno = EAFNOSUPPORT;
1.49 markus 499: continue;
1.290 djm 500: }
1.49 markus 501: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
502: ntop, sizeof(ntop), strport, sizeof(strport),
503: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.290 djm 504: oerrno = errno;
1.265 djm 505: error("%s: getnameinfo failed", __func__);
1.290 djm 506: errno = oerrno;
1.49 markus 507: continue;
508: }
509: debug("Connecting to %.200s [%.100s] port %s.",
510: host, ntop, strport);
511:
512: /* Create a socket for connecting. */
1.302 dtucker 513: sock = ssh_create_socket(ai);
1.292 stsp 514: if (sock < 0) {
1.110 markus 515: /* Any error is already output */
1.290 djm 516: errno = 0;
1.49 markus 517: continue;
1.292 stsp 518: }
1.49 markus 519:
1.141 djm 520: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 521: timeout_ms) >= 0) {
1.49 markus 522: /* Successful connection. */
1.102 markus 523: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 524: break;
1.49 markus 525: } else {
1.290 djm 526: oerrno = errno;
1.131 itojun 527: debug("connect to address %s port %s: %s",
528: ntop, strport, strerror(errno));
1.38 markus 529: close(sock);
1.181 markus 530: sock = -1;
1.290 djm 531: errno = oerrno;
1.38 markus 532: }
533: }
1.181 markus 534: if (sock != -1)
1.49 markus 535: break; /* Successful connection. */
1.38 markus 536: }
1.49 markus 537:
1.38 markus 538: /* Return failure if we didn't get a successful connection. */
1.181 markus 539: if (sock == -1) {
1.159 markus 540: error("ssh: connect to host %s port %s: %s",
1.290 djm 541: host, strport, errno == 0 ? "failure" : strerror(errno));
542: return -1;
1.130 itojun 543: }
1.38 markus 544:
545: debug("Connection established.");
1.90 markus 546:
1.155 markus 547: /* Set SO_KEEPALIVE if requested. */
1.202 djm 548: if (want_keepalive &&
1.90 markus 549: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
550: sizeof(on)) < 0)
551: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 552:
553: /* Set the connection. */
1.286 djm 554: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
555: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 556:
1.286 djm 557: return 0;
1.59 markus 558: }
559:
1.241 djm 560: int
1.286 djm 561: ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs,
1.241 djm 562: struct sockaddr_storage *hostaddr, u_short port, int family,
1.302 dtucker 563: int connection_attempts, int *timeout_ms, int want_keepalive)
1.241 djm 564: {
565: if (options.proxy_command == NULL) {
1.286 djm 566: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
1.302 dtucker 567: family, connection_attempts, timeout_ms, want_keepalive);
1.241 djm 568: } else if (strcmp(options.proxy_command, "-") == 0) {
1.286 djm 569: if ((ssh_packet_set_connection(ssh,
570: STDIN_FILENO, STDOUT_FILENO)) == NULL)
571: return -1; /* ssh_packet_set_connection logs error */
572: return 0;
1.241 djm 573: } else if (options.proxy_use_fdpass) {
1.286 djm 574: return ssh_proxy_fdpass_connect(ssh, host, port,
1.241 djm 575: options.proxy_command);
576: }
1.286 djm 577: return ssh_proxy_connect(ssh, host, port, options.proxy_command);
1.241 djm 578: }
579:
1.235 djm 580: static void
581: send_client_banner(int connection_out, int minor1)
582: {
583: /* Send our own protocol version identification. */
1.276 djm 584: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
585: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
1.270 markus 586: if (atomicio(vwrite, connection_out, client_version_string,
1.235 djm 587: strlen(client_version_string)) != strlen(client_version_string))
588: fatal("write: %.100s", strerror(errno));
589: chop(client_version_string);
590: debug("Local version string %.100s", client_version_string);
591: }
592:
1.43 markus 593: /*
1.39 deraadt 594: * Waits for the server identification string, and sends our own
595: * identification string.
596: */
1.213 andreas 597: void
1.202 djm 598: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 599: {
1.38 markus 600: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 601: int remote_major, remote_minor, mismatch;
1.38 markus 602: int connection_in = packet_get_connection_in();
603: int connection_out = packet_get_connection_out();
1.185 djm 604: u_int i, n;
1.202 djm 605: size_t len;
1.282 djm 606: int rc;
1.38 markus 607:
1.275 djm 608: send_client_banner(connection_out, 0);
1.235 djm 609:
1.163 avsm 610: /* Read other side's version identification. */
1.185 djm 611: for (n = 0;;) {
1.75 markus 612: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 613: if (timeout_ms > 0) {
1.282 djm 614: rc = waitrfd(connection_in, &timeout_ms);
615: if (rc == -1 && errno == ETIMEDOUT) {
1.202 djm 616: fatal("Connection timed out during "
617: "banner exchange");
1.282 djm 618: } else if (rc == -1) {
619: fatal("%s: %s",
620: __func__, strerror(errno));
1.202 djm 621: }
622: }
623:
1.270 markus 624: len = atomicio(read, connection_in, &buf[i], 1);
1.167 djm 625: if (len != 1 && errno == EPIPE)
1.202 djm 626: fatal("ssh_exchange_identification: "
627: "Connection closed by remote host");
1.163 avsm 628: else if (len != 1)
1.202 djm 629: fatal("ssh_exchange_identification: "
630: "read: %.100s", strerror(errno));
1.75 markus 631: if (buf[i] == '\r') {
632: buf[i] = '\n';
633: buf[i + 1] = 0;
634: continue; /**XXX wait for \n */
635: }
636: if (buf[i] == '\n') {
637: buf[i + 1] = 0;
638: break;
639: }
1.185 djm 640: if (++n > 65536)
1.202 djm 641: fatal("ssh_exchange_identification: "
642: "No banner received");
1.38 markus 643: }
1.75 markus 644: buf[sizeof(buf) - 1] = 0;
1.76 markus 645: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 646: break;
1.75 markus 647: debug("ssh_exchange_identification: %s", buf);
1.38 markus 648: }
1.59 markus 649: server_version_string = xstrdup(buf);
1.38 markus 650:
1.40 markus 651: /*
652: * Check that the versions match. In future this might accept
653: * several versions and set appropriate flags to handle them.
654: */
1.59 markus 655: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
656: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 657: fatal("Bad remote protocol version identification: '%.100s'", buf);
658: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 659: remote_major, remote_minor, remote_version);
1.38 markus 660:
1.255 markus 661: active_state->compat = compat_datafellows(remote_version);
1.64 markus 662: mismatch = 0;
1.59 markus 663:
1.116 deraadt 664: switch (remote_major) {
1.276 djm 665: case 2:
666: break;
1.64 markus 667: case 1:
1.276 djm 668: if (remote_minor != 99)
1.64 markus 669: mismatch = 1;
670: break;
1.68 markus 671: default:
1.64 markus 672: mismatch = 1;
673: break;
1.38 markus 674: }
1.64 markus 675: if (mismatch)
1.38 markus 676: fatal("Protocol major versions differ: %d vs. %d",
1.275 djm 677: PROTOCOL_MAJOR_2, remote_major);
1.243 djm 678: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
679: logit("Server version \"%.100s\" uses unsafe RSA signature "
680: "scheme; disabling use of RSA keys", remote_version);
1.59 markus 681: chop(server_version_string);
1.1 deraadt 682: }
683:
1.96 markus 684: /* defaults to 'no' */
1.109 itojun 685: static int
1.112 markus 686: confirm(const char *prompt)
1.1 deraadt 687: {
1.119 markus 688: const char *msg, *again = "Please type 'yes' or 'no': ";
689: char *p;
690: int ret = -1;
1.96 markus 691:
692: if (options.batch_mode)
693: return 0;
1.119 markus 694: for (msg = prompt;;msg = again) {
695: p = read_passphrase(msg, RP_ECHO);
1.289 djm 696: if (p == NULL)
697: return 0;
698: p[strcspn(p, "\n")] = '\0';
699: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 700: ret = 0;
1.289 djm 701: else if (strcasecmp(p, "yes") == 0)
1.119 markus 702: ret = 1;
1.238 djm 703: free(p);
1.119 markus 704: if (ret != -1)
705: return ret;
1.1 deraadt 706: }
707: }
708:
1.219 djm 709: static int
1.305 djm 710: check_host_cert(const char *host, const struct sshkey *key)
1.219 djm 711: {
712: const char *reason;
1.305 djm 713: int r;
1.219 djm 714:
1.305 djm 715: if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) {
1.219 djm 716: error("%s", reason);
717: return 0;
718: }
1.305 djm 719: if (sshbuf_len(key->cert->critical) != 0) {
1.223 djm 720: error("Certificate for %s contains unsupported "
721: "critical options(s)", host);
1.219 djm 722: return 0;
723: }
1.305 djm 724: if ((r = sshkey_check_cert_sigtype(key,
725: options.ca_sign_algorithms)) != 0) {
726: logit("%s: certificate signature algorithm %s: %s", __func__,
727: (key->cert == NULL || key->cert->signature_type == NULL) ?
728: "(null)" : key->cert->signature_type, ssh_err(r));
729: return 0;
730: }
731:
1.219 djm 732: return 1;
733: }
734:
1.229 djm 735: static int
736: sockaddr_is_local(struct sockaddr *hostaddr)
737: {
738: switch (hostaddr->sa_family) {
739: case AF_INET:
740: return (ntohl(((struct sockaddr_in *)hostaddr)->
741: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
742: case AF_INET6:
743: return IN6_IS_ADDR_LOOPBACK(
744: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
745: default:
746: return 0;
747: }
748: }
749:
750: /*
751: * Prepare the hostname and ip address strings that are used to lookup
752: * host keys in known_hosts files. These may have a port number appended.
753: */
754: void
755: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
756: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
757: {
758: char ntop[NI_MAXHOST];
759:
760: /*
761: * We don't have the remote ip-address for connections
762: * using a proxy command
763: */
764: if (hostfile_ipaddr != NULL) {
765: if (options.proxy_command == NULL) {
766: if (getnameinfo(hostaddr, hostaddr->sa_len,
767: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 768: fatal("%s: getnameinfo failed", __func__);
1.229 djm 769: *hostfile_ipaddr = put_host_port(ntop, port);
770: } else {
771: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
772: "command>");
773: }
774: }
775:
776: /*
777: * Allow the user to record the key under a different name or
778: * differentiate a non-standard port. This is useful for ssh
779: * tunneling over forwarded connections or if you run multiple
780: * sshd's on different ports on the same machine.
781: */
782: if (hostfile_hostname != NULL) {
783: if (options.host_key_alias != NULL) {
784: *hostfile_hostname = xstrdup(options.host_key_alias);
785: debug("using hostkeyalias: %s", *hostfile_hostname);
786: } else {
787: *hostfile_hostname = put_host_port(hostname, port);
788: }
789: }
790: }
791:
1.39 deraadt 792: /*
1.108 markus 793: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 794: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 795: */
1.197 dtucker 796: #define RDRW 0
797: #define RDONLY 1
798: #define ROQUIET 2
1.109 itojun 799: static int
1.197 dtucker 800: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 801: struct sshkey *host_key, int readonly,
1.234 djm 802: char **user_hostfiles, u_int num_user_hostfiles,
803: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 804: {
1.234 djm 805: HostStatus host_status;
806: HostStatus ip_status;
1.279 markus 807: struct sshkey *raw_key = NULL;
1.189 dtucker 808: char *ip = NULL, *host = NULL;
1.204 grunk 809: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 810: char msg[1024];
1.234 djm 811: const char *type;
812: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 813: int len, cancelled_forwarding = 0;
1.234 djm 814: int local = sockaddr_is_local(hostaddr);
1.280 markus 815: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 816: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 817: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 818: u_int i;
1.49 markus 819:
820: /*
821: * Force accepting of the host key for loopback/localhost. The
822: * problem is that if the home directory is NFS-mounted to multiple
823: * machines, localhost will refer to a different machine in each of
824: * them, and the user will get bogus HOST_CHANGED warnings. This
825: * essentially disables host authentication for localhost; however,
826: * this is probably not a real problem.
827: */
1.111 markus 828: if (options.no_host_authentication_for_localhost == 1 && local &&
829: options.host_key_alias == NULL) {
1.88 markus 830: debug("Forcing accepting of host key for "
831: "loopback/localhost.");
1.108 markus 832: return 0;
1.49 markus 833: }
1.42 markus 834:
835: /*
1.229 djm 836: * Prepare the hostname and address strings used for hostkey lookup.
837: * In some cases, these will have a port number appended.
1.42 markus 838: */
1.229 djm 839: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 840:
841: /*
1.88 markus 842: * Turn off check_host_ip if the connection is to localhost, via proxy
843: * command or if we don't have a hostname to compare with
844: */
1.189 dtucker 845: if (options.check_host_ip && (local ||
846: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 847: options.check_host_ip = 0;
1.86 markus 848:
1.229 djm 849: host_hostkeys = init_hostkeys();
1.234 djm 850: for (i = 0; i < num_user_hostfiles; i++)
851: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
852: for (i = 0; i < num_system_hostfiles; i++)
853: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 854:
855: ip_hostkeys = NULL;
856: if (!want_cert && options.check_host_ip) {
857: ip_hostkeys = init_hostkeys();
1.234 djm 858: for (i = 0; i < num_user_hostfiles; i++)
859: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
860: for (i = 0; i < num_system_hostfiles; i++)
861: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 862: }
1.38 markus 863:
1.219 djm 864: retry:
1.229 djm 865: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 866: want_cert = sshkey_is_cert(host_key);
867: type = sshkey_type(host_key);
1.219 djm 868:
1.46 markus 869: /*
1.170 djm 870: * Check if the host key is present in the user's list of known
1.40 markus 871: * hosts or in the systemwide list.
872: */
1.229 djm 873: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
874: &host_found);
875:
1.40 markus 876: /*
877: * Also perform check for the ip address, skip the check if we are
1.219 djm 878: * localhost, looking for a certificate, or the hostname was an ip
879: * address to begin with.
1.40 markus 880: */
1.229 djm 881: if (!want_cert && ip_hostkeys != NULL) {
882: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
883: &ip_found);
1.38 markus 884: if (host_status == HOST_CHANGED &&
1.229 djm 885: (ip_status != HOST_CHANGED ||
886: (ip_found != NULL &&
1.280 markus 887: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 888: host_ip_differ = 1;
889: } else
890: ip_status = host_status;
891:
892: switch (host_status) {
893: case HOST_OK:
894: /* The host is known and the key matches. */
1.219 djm 895: debug("Host '%.200s' is known and matches the %s host %s.",
896: host, type, want_cert ? "certificate" : "key");
1.229 djm 897: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
898: host_found->file, host_found->line);
1.281 djm 899: if (want_cert &&
900: !check_host_cert(options.host_key_alias == NULL ?
901: hostname : options.host_key_alias, host_key))
1.219 djm 902: goto fail;
1.88 markus 903: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 904: if (readonly || want_cert)
1.138 itojun 905: logit("%s host key for IP address "
1.108 markus 906: "'%.128s' not in list of known hosts.",
907: type, ip);
1.234 djm 908: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 909: host_key, options.hash_known_hosts))
1.138 itojun 910: logit("Failed to add the %s host key for IP "
1.108 markus 911: "address '%.128s' to the list of known "
1.262 dtucker 912: "hosts (%.500s).", type, ip,
1.234 djm 913: user_hostfiles[0]);
1.88 markus 914: else
1.138 itojun 915: logit("Warning: Permanently added the %s host "
1.108 markus 916: "key for IP address '%.128s' to the list "
917: "of known hosts.", type, ip);
1.209 grunk 918: } else if (options.visual_host_key) {
1.259 djm 919: fp = sshkey_fingerprint(host_key,
1.254 djm 920: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 921: ra = sshkey_fingerprint(host_key,
1.254 djm 922: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 923: if (fp == NULL || ra == NULL)
924: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 925: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 926: free(ra);
927: free(fp);
1.38 markus 928: }
1.257 djm 929: hostkey_trusted = 1;
1.38 markus 930: break;
931: case HOST_NEW:
1.197 dtucker 932: if (options.host_key_alias == NULL && port != 0 &&
933: port != SSH_DEFAULT_PORT) {
934: debug("checking without port identifier");
1.212 stevesk 935: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 936: ROQUIET, user_hostfiles, num_user_hostfiles,
937: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 938: debug("found matching key w/out port");
939: break;
940: }
941: }
1.219 djm 942: if (readonly || want_cert)
1.108 markus 943: goto fail;
1.38 markus 944: /* The host is new. */
1.285 djm 945: if (options.strict_host_key_checking ==
946: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 947: /*
948: * User has requested strict host key checking. We
949: * will not add the host key automatically. The only
950: * alternative left is to abort.
951: */
952: error("No %s host key is known for %.200s and you "
953: "have requested strict checking.", type, host);
954: goto fail;
1.285 djm 955: } else if (options.strict_host_key_checking ==
956: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 957: char msg1[1024], msg2[1024];
958:
1.229 djm 959: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 960: snprintf(msg1, sizeof(msg1),
1.168 djm 961: "\nbut keys of different type are already"
962: " known for this host.");
1.145 jakob 963: else
964: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 965: /* The default */
1.259 djm 966: fp = sshkey_fingerprint(host_key,
1.254 djm 967: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 968: ra = sshkey_fingerprint(host_key,
1.254 djm 969: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 970: if (fp == NULL || ra == NULL)
971: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 972: msg2[0] = '\0';
973: if (options.verify_host_key_dns) {
1.153 jakob 974: if (matching_host_key_dns)
1.145 jakob 975: snprintf(msg2, sizeof(msg2),
976: "Matching host key fingerprint"
977: " found in DNS.\n");
978: else
979: snprintf(msg2, sizeof(msg2),
980: "No matching host key fingerprint"
981: " found in DNS.\n");
982: }
1.119 markus 983: snprintf(msg, sizeof(msg),
1.108 markus 984: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 985: "established%s\n"
1.209 grunk 986: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 987: "Are you sure you want to continue connecting "
1.132 markus 988: "(yes/no)? ",
1.209 grunk 989: host, ip, msg1, type, fp,
990: options.visual_host_key ? "\n" : "",
991: options.visual_host_key ? ra : "",
992: msg2);
1.238 djm 993: free(ra);
994: free(fp);
1.119 markus 995: if (!confirm(msg))
1.108 markus 996: goto fail;
1.257 djm 997: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 998: }
1.161 djm 999: /*
1.285 djm 1000: * If in "new" or "off" strict mode, add the key automatically
1001: * to the local known_hosts file.
1.161 djm 1002: */
1.88 markus 1003: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 1004: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 1005: hostp = hostline;
1.161 djm 1006: if (options.hash_known_hosts) {
1007: /* Add hash of host and IP separately */
1.234 djm 1008: r = add_host_to_hostfile(user_hostfiles[0],
1009: host, host_key, options.hash_known_hosts) &&
1010: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 1011: host_key, options.hash_known_hosts);
1012: } else {
1013: /* Add unhashed "host,ip" */
1.234 djm 1014: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 1015: hostline, host_key,
1016: options.hash_known_hosts);
1017: }
1018: } else {
1.234 djm 1019: r = add_host_to_hostfile(user_hostfiles[0], host,
1020: host_key, options.hash_known_hosts);
1.38 markus 1021: hostp = host;
1.161 djm 1022: }
1.38 markus 1023:
1.161 djm 1024: if (!r)
1.138 itojun 1025: logit("Failed to add the host to the list of known "
1.234 djm 1026: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 1027: else
1.138 itojun 1028: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 1029: "list of known hosts.", hostp, type);
1.38 markus 1030: break;
1.220 djm 1031: case HOST_REVOKED:
1032: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1033: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1034: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1035: error("The %s host key for %s is marked as revoked.", type, host);
1036: error("This could mean that a stolen key is being used to");
1037: error("impersonate this host.");
1038:
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: */
1.285 djm 1043: if (options.strict_host_key_checking !=
1044: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 1045: error("%s host key for %.200s was revoked and you have "
1046: "requested strict checking.", type, host);
1047: goto fail;
1048: }
1049: goto continue_unsafe;
1050:
1.38 markus 1051: case HOST_CHANGED:
1.219 djm 1052: if (want_cert) {
1053: /*
1054: * This is only a debug() since it is valid to have
1055: * CAs with wildcard DNS matches that don't match
1056: * all hosts that one might visit.
1057: */
1058: debug("Host certificate authority does not "
1.229 djm 1059: "match %s in %s:%lu", CA_MARKER,
1060: host_found->file, host_found->line);
1.219 djm 1061: goto fail;
1062: }
1.197 dtucker 1063: if (readonly == ROQUIET)
1064: goto fail;
1.38 markus 1065: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1066: char *key_msg;
1.38 markus 1067: if (ip_status == HOST_NEW)
1.158 avsm 1068: key_msg = "is unknown";
1.38 markus 1069: else if (ip_status == HOST_OK)
1.158 avsm 1070: key_msg = "is unchanged";
1.38 markus 1071: else
1.158 avsm 1072: key_msg = "has a different value";
1.38 markus 1073: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1074: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1075: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1076: error("The %s host key for %s has changed,", type, host);
1.208 ian 1077: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1078: error("%s. This could either mean that", key_msg);
1.38 markus 1079: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1080: error("and its host key have changed at the same time.");
1.88 markus 1081: if (ip_status != HOST_NEW)
1.229 djm 1082: error("Offending key for IP in %s:%lu",
1083: ip_found->file, ip_found->line);
1.38 markus 1084: }
1085: /* The host key has changed. */
1.150 jakob 1086: warn_changed_key(host_key);
1.38 markus 1087: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1088: user_hostfiles[0]);
1.280 markus 1089: error("Offending %s key in %s:%lu",
1090: sshkey_type(host_found->key),
1.229 djm 1091: host_found->file, host_found->line);
1.38 markus 1092:
1.40 markus 1093: /*
1094: * If strict host key checking is in use, the user will have
1095: * to edit the key manually and we can only abort.
1096: */
1.285 djm 1097: if (options.strict_host_key_checking !=
1098: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 1099: error("%s host key for %.200s has changed and you have "
1100: "requested strict checking.", type, host);
1101: goto fail;
1102: }
1.38 markus 1103:
1.220 djm 1104: continue_unsafe:
1.40 markus 1105: /*
1106: * If strict host key checking has not been requested, allow
1.144 djm 1107: * the connection but without MITM-able authentication or
1.194 stevesk 1108: * forwarding.
1.40 markus 1109: */
1.38 markus 1110: if (options.password_authentication) {
1.108 markus 1111: error("Password authentication is disabled to avoid "
1112: "man-in-the-middle attacks.");
1.38 markus 1113: options.password_authentication = 0;
1.210 dtucker 1114: cancelled_forwarding = 1;
1.144 djm 1115: }
1116: if (options.kbd_interactive_authentication) {
1117: error("Keyboard-interactive authentication is disabled"
1118: " to avoid man-in-the-middle attacks.");
1119: options.kbd_interactive_authentication = 0;
1120: options.challenge_response_authentication = 0;
1.210 dtucker 1121: cancelled_forwarding = 1;
1.144 djm 1122: }
1123: if (options.challenge_response_authentication) {
1124: error("Challenge/response authentication is disabled"
1125: " to avoid man-in-the-middle attacks.");
1126: options.challenge_response_authentication = 0;
1.210 dtucker 1127: cancelled_forwarding = 1;
1.38 markus 1128: }
1129: if (options.forward_agent) {
1.108 markus 1130: error("Agent forwarding is disabled to avoid "
1131: "man-in-the-middle attacks.");
1.38 markus 1132: options.forward_agent = 0;
1.210 dtucker 1133: cancelled_forwarding = 1;
1.83 markus 1134: }
1135: if (options.forward_x11) {
1.108 markus 1136: error("X11 forwarding is disabled to avoid "
1137: "man-in-the-middle attacks.");
1.83 markus 1138: options.forward_x11 = 0;
1.210 dtucker 1139: cancelled_forwarding = 1;
1.83 markus 1140: }
1.108 markus 1141: if (options.num_local_forwards > 0 ||
1142: options.num_remote_forwards > 0) {
1143: error("Port forwarding is disabled to avoid "
1144: "man-in-the-middle attacks.");
1145: options.num_local_forwards =
1.118 deraadt 1146: options.num_remote_forwards = 0;
1.210 dtucker 1147: cancelled_forwarding = 1;
1.194 stevesk 1148: }
1149: if (options.tun_open != SSH_TUNMODE_NO) {
1150: error("Tunnel forwarding is disabled to avoid "
1151: "man-in-the-middle attacks.");
1152: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1153: cancelled_forwarding = 1;
1.38 markus 1154: }
1.210 dtucker 1155: if (options.exit_on_forward_failure && cancelled_forwarding)
1156: fatal("Error: forwarding disabled due to host key "
1157: "check failure");
1158:
1.40 markus 1159: /*
1160: * XXX Should permit the user to change to use the new id.
1161: * This could be done by converting the host key to an
1162: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1163: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1164: * accept the authentication.
1165: */
1.38 markus 1166: break;
1.132 markus 1167: case HOST_FOUND:
1168: fatal("internal error");
1169: break;
1.88 markus 1170: }
1171:
1172: if (options.check_host_ip && host_status != HOST_CHANGED &&
1173: ip_status == HOST_CHANGED) {
1.119 markus 1174: snprintf(msg, sizeof(msg),
1175: "Warning: the %s host key for '%.200s' "
1176: "differs from the key for the IP address '%.128s'"
1.229 djm 1177: "\nOffending key for IP in %s:%lu",
1178: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1179: if (host_status == HOST_OK) {
1180: len = strlen(msg);
1181: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1182: "\nMatching host key in %s:%lu",
1183: host_found->file, host_found->line);
1.119 markus 1184: }
1.285 djm 1185: if (options.strict_host_key_checking ==
1186: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1187: strlcat(msg, "\nAre you sure you want "
1188: "to continue connecting (yes/no)? ", sizeof(msg));
1189: if (!confirm(msg))
1.108 markus 1190: goto fail;
1.285 djm 1191: } else if (options.strict_host_key_checking !=
1192: SSH_STRICT_HOSTKEY_OFF) {
1193: logit("%s", msg);
1194: error("Exiting, you have requested strict checking.");
1195: goto fail;
1.119 markus 1196: } else {
1.143 djm 1197: logit("%s", msg);
1.88 markus 1198: }
1.257 djm 1199: }
1200:
1201: if (!hostkey_trusted && options.update_hostkeys) {
1202: debug("%s: hostkey not known or explicitly trusted: "
1203: "disabling UpdateHostkeys", __func__);
1204: options.update_hostkeys = 0;
1.38 markus 1205: }
1.82 provos 1206:
1.238 djm 1207: free(ip);
1208: free(host);
1.229 djm 1209: if (host_hostkeys != NULL)
1210: free_hostkeys(host_hostkeys);
1211: if (ip_hostkeys != NULL)
1212: free_hostkeys(ip_hostkeys);
1.108 markus 1213: return 0;
1214:
1215: fail:
1.220 djm 1216: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1217: /*
1218: * No matching certificate. Downgrade cert to raw key and
1219: * search normally.
1220: */
1221: debug("No matching CA found. Retry with plain key");
1.280 markus 1222: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1223: fatal("%s: sshkey_from_private: %s",
1224: __func__, ssh_err(r));
1225: if ((r = sshkey_drop_cert(raw_key)) != 0)
1226: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1227: host_key = raw_key;
1228: goto retry;
1229: }
1.293 dtucker 1230: sshkey_free(raw_key);
1.238 djm 1231: free(ip);
1232: free(host);
1.229 djm 1233: if (host_hostkeys != NULL)
1234: free_hostkeys(host_hostkeys);
1235: if (ip_hostkeys != NULL)
1236: free_hostkeys(ip_hostkeys);
1.108 markus 1237: return -1;
1238: }
1239:
1.140 jakob 1240: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1241: int
1.279 markus 1242: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1243: {
1.267 djm 1244: u_int i;
1.250 djm 1245: int r = -1, flags = 0;
1.267 djm 1246: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1247: struct sshkey *plain = NULL;
1.229 djm 1248:
1.252 djm 1249: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1250: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1251: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1252: r = -1;
1253: goto out;
1254: }
1255:
1.267 djm 1256: if (sshkey_is_cert(host_key)) {
1257: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1258: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1259: error("%s: fingerprint CA key: %s",
1260: __func__, ssh_err(r));
1261: r = -1;
1262: goto out;
1263: }
1264: sshkey_format_cert_validity(host_key->cert,
1265: valid, sizeof(valid));
1266: debug("Server host certificate: %s %s, serial %llu "
1267: "ID \"%s\" CA %s %s valid %s",
1268: sshkey_ssh_name(host_key), fp,
1.269 djm 1269: (unsigned long long)host_key->cert->serial,
1270: host_key->cert->key_id,
1.267 djm 1271: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1272: valid);
1273: for (i = 0; i < host_key->cert->nprincipals; i++) {
1274: debug2("Server host certificate hostname: %s",
1275: host_key->cert->principals[i]);
1276: }
1277: } else {
1.276 djm 1278: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1279: }
1.252 djm 1280:
1281: if (sshkey_equal(previous_host_key, host_key)) {
1282: debug2("%s: server host key %s %s matches cached key",
1283: __func__, sshkey_type(host_key), fp);
1284: r = 0;
1285: goto out;
1286: }
1287:
1288: /* Check in RevokedHostKeys file if specified */
1289: if (options.revoked_host_keys != NULL) {
1290: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1291: switch (r) {
1292: case 0:
1293: break; /* not revoked */
1294: case SSH_ERR_KEY_REVOKED:
1295: error("Host key %s %s revoked by file %s",
1296: sshkey_type(host_key), fp,
1297: options.revoked_host_keys);
1298: r = -1;
1299: goto out;
1300: default:
1301: error("Error checking host key %s %s in "
1302: "revoked keys file %s: %s", sshkey_type(host_key),
1303: fp, options.revoked_host_keys, ssh_err(r));
1304: r = -1;
1305: goto out;
1306: }
1.250 djm 1307: }
1308:
1.247 djm 1309: if (options.verify_host_key_dns) {
1310: /*
1311: * XXX certs are not yet supported for DNS, so downgrade
1312: * them and try the plain key.
1313: */
1.252 djm 1314: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1315: goto out;
1316: if (sshkey_is_cert(plain))
1317: sshkey_drop_cert(plain);
1.247 djm 1318: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1319: if (flags & DNS_VERIFY_FOUND) {
1320: if (options.verify_host_key_dns == 1 &&
1321: flags & DNS_VERIFY_MATCH &&
1322: flags & DNS_VERIFY_SECURE) {
1.250 djm 1323: r = 0;
1.252 djm 1324: goto out;
1.247 djm 1325: }
1326: if (flags & DNS_VERIFY_MATCH) {
1327: matching_host_key_dns = 1;
1328: } else {
1.287 djm 1329: warn_changed_key(plain);
1330: error("Update the SSHFP RR in DNS "
1331: "with the new host key to get rid "
1332: "of this message.");
1.247 djm 1333: }
1.153 jakob 1334: }
1.140 jakob 1335: }
1336: }
1.250 djm 1337: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1338: options.user_hostfiles, options.num_user_hostfiles,
1339: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1340:
1.252 djm 1341: out:
1342: sshkey_free(plain);
1343: free(fp);
1.267 djm 1344: free(cafp);
1.250 djm 1345: if (r == 0 && host_key != NULL) {
1.280 markus 1346: sshkey_free(previous_host_key);
1347: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1348: }
1349:
1350: return r;
1.51 markus 1351: }
1.70 markus 1352:
1.51 markus 1353: /*
1354: * Starts a dialog with the server, and authenticates the current user on the
1355: * server. This does not need any extra privileges. The basic connection
1356: * to the server must already have been established before this is called.
1357: * If login fails, this function prints an error and never returns.
1358: * This function does not require super-user privileges.
1359: */
1360: void
1.120 markus 1361: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1362: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1363: {
1.241 djm 1364: char *host;
1.70 markus 1365: char *server_user, *local_user;
1366:
1367: local_user = xstrdup(pw->pw_name);
1368: server_user = options.user ? options.user : local_user;
1.51 markus 1369:
1370: /* Convert the user-supplied hostname into all lowercase. */
1371: host = xstrdup(orighost);
1.241 djm 1372: lowercase(host);
1.51 markus 1373:
1374: /* Exchange protocol version identification strings with the server. */
1.202 djm 1375: ssh_exchange_identification(timeout_ms);
1.51 markus 1376:
1377: /* Put the connection into non-blocking mode. */
1378: packet_set_nonblocking();
1379:
1380: /* key exchange */
1381: /* authenticate user */
1.261 dtucker 1382: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.276 djm 1383: ssh_kex2(host, hostaddr, port);
1384: ssh_userauth2(local_user, server_user, host, sensitive);
1.238 djm 1385: free(local_user);
1.97 markus 1386: }
1387:
1388: void
1389: ssh_put_password(char *password)
1390: {
1391: int size;
1392: char *padded;
1393:
1.99 deraadt 1394: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1395: packet_put_cstring(password);
1.99 deraadt 1396: return;
1397: }
1.272 deraadt 1398: size = ROUNDUP(strlen(password) + 1, 32);
1.179 djm 1399: padded = xcalloc(1, size);
1.97 markus 1400: strlcpy(padded, password, size);
1401: packet_put_string(padded, size);
1.245 djm 1402: explicit_bzero(padded, size);
1.238 djm 1403: free(padded);
1.132 markus 1404: }
1405:
1406: /* print all known host keys for a given host, but skip keys of given type */
1407: static int
1.279 markus 1408: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1409: {
1.242 djm 1410: int type[] = {
1411: KEY_RSA,
1412: KEY_DSA,
1413: KEY_ECDSA,
1414: KEY_ED25519,
1.297 markus 1415: KEY_XMSS,
1.242 djm 1416: -1
1417: };
1.229 djm 1418: int i, ret = 0;
1419: char *fp, *ra;
1420: const struct hostkey_entry *found;
1.132 markus 1421:
1422: for (i = 0; type[i] != -1; i++) {
1423: if (type[i] == key->type)
1424: continue;
1.229 djm 1425: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1426: continue;
1.259 djm 1427: fp = sshkey_fingerprint(found->key,
1.254 djm 1428: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1429: ra = sshkey_fingerprint(found->key,
1.254 djm 1430: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1431: if (fp == NULL || ra == NULL)
1432: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1433: logit("WARNING: %s key found for host %s\n"
1434: "in %s:%lu\n"
1435: "%s key fingerprint %s.",
1.300 markus 1436: sshkey_type(found->key),
1.229 djm 1437: found->host, found->file, found->line,
1.300 markus 1438: sshkey_type(found->key), fp);
1.229 djm 1439: if (options.visual_host_key)
1440: logit("%s", ra);
1.238 djm 1441: free(ra);
1442: free(fp);
1.229 djm 1443: ret = 1;
1.132 markus 1444: }
1.229 djm 1445: return ret;
1.150 jakob 1446: }
1447:
1448: static void
1.279 markus 1449: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1450: {
1451: char *fp;
1452:
1.259 djm 1453: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1454: SSH_FP_DEFAULT);
1.259 djm 1455: if (fp == NULL)
1456: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1457:
1458: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1459: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1460: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1461: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1462: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1463: error("It is also possible that a host key has just been changed.");
1.150 jakob 1464: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.300 markus 1465: sshkey_type(host_key), fp);
1.150 jakob 1466: error("Please contact your system administrator.");
1467:
1.238 djm 1468: free(fp);
1.171 reyk 1469: }
1470:
1471: /*
1472: * Execute a local command
1473: */
1474: int
1475: ssh_local_cmd(const char *args)
1476: {
1477: char *shell;
1478: pid_t pid;
1479: int status;
1.231 djm 1480: void (*osighand)(int);
1.171 reyk 1481:
1482: if (!options.permit_local_command ||
1483: args == NULL || !*args)
1484: return (1);
1485:
1.226 djm 1486: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1487: shell = _PATH_BSHELL;
1488:
1.231 djm 1489: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1490: pid = fork();
1491: if (pid == 0) {
1.232 djm 1492: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1493: debug3("Executing %s -c \"%s\"", shell, args);
1494: execl(shell, shell, "-c", args, (char *)NULL);
1495: error("Couldn't execute %s -c \"%s\": %s",
1496: shell, args, strerror(errno));
1497: _exit(1);
1498: } else if (pid == -1)
1499: fatal("fork failed: %.100s", strerror(errno));
1500: while (waitpid(pid, &status, 0) == -1)
1501: if (errno != EINTR)
1502: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1503: signal(SIGCHLD, osighand);
1.171 reyk 1504:
1505: if (!WIFEXITED(status))
1506: return (1);
1507:
1508: return (WEXITSTATUS(status));
1.266 jcs 1509: }
1510:
1511: void
1.294 djm 1512: maybe_add_key_to_agent(char *authfile, const struct sshkey *private,
1513: char *comment, char *passphrase)
1.266 jcs 1514: {
1515: int auth_sock = -1, r;
1516:
1517: if (options.add_keys_to_agent == 0)
1518: return;
1519:
1520: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1521: debug3("no authentication agent, not adding key");
1522: return;
1523: }
1524:
1525: if (options.add_keys_to_agent == 2 &&
1526: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1527: debug3("user denied adding this key");
1.273 dtucker 1528: close(auth_sock);
1.266 jcs 1529: return;
1530: }
1531:
1532: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1.297 markus 1533: (options.add_keys_to_agent == 3), 0)) == 0)
1.266 jcs 1534: debug("identity added to agent: %s", authfile);
1535: else
1536: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1537: close(auth_sock);
1.1 deraadt 1538: }