Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.308
1.308 ! dtucker 1: /* $OpenBSD: sshconnect.c,v 1.307 2018/11/16 06:17:38 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 */
1.307 djm 68: extern int debug_flag;
1.43 markus 69: extern Options options;
1.50 markus 70: extern char *__progname;
1.91 markus 71:
1.279 markus 72: static int show_other_keys(struct hostkeys *, struct sshkey *);
73: static void warn_changed_key(struct sshkey *);
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:
1.307 djm 90: static void
91: stderr_null(void)
92: {
93: int devnull;
94:
95: if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1) {
96: error("Can't open %s for stderr redirection: %s",
97: _PATH_DEVNULL, strerror(errno));
98: return;
99: }
100: if (devnull == STDERR_FILENO)
101: return;
102: if (dup2(devnull, STDERR_FILENO) == -1)
103: error("Cannot redirect stderr to %s", _PATH_DEVNULL);
104: if (devnull > STDERR_FILENO)
105: close(devnull);
106: }
107:
1.239 djm 108: /*
109: * Connect to the given ssh server using a proxy command that passes a
110: * a connected fd back to us.
111: */
112: static int
1.286 djm 113: ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, u_short port,
1.239 djm 114: const char *proxy_command)
115: {
116: char *command_string;
117: int sp[2], sock;
118: pid_t pid;
119: char *shell;
120:
121: if ((shell = getenv("SHELL")) == NULL)
122: shell = _PATH_BSHELL;
123:
124: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
125: fatal("Could not create socketpair to communicate with "
126: "proxy dialer: %.100s", strerror(errno));
127:
128: command_string = expand_proxy_command(proxy_command, options.user,
129: host, port);
130: debug("Executing proxy dialer command: %.500s", command_string);
131:
132: /* Fork and execute the proxy command. */
133: if ((pid = fork()) == 0) {
134: char *argv[10];
135:
136: close(sp[1]);
137: /* Redirect stdin and stdout. */
138: if (sp[0] != 0) {
139: if (dup2(sp[0], 0) < 0)
140: perror("dup2 stdin");
141: }
142: if (sp[0] != 1) {
143: if (dup2(sp[0], 1) < 0)
144: perror("dup2 stdout");
145: }
146: if (sp[0] >= 2)
147: close(sp[0]);
148:
149: /*
1.307 djm 150: * Stderr is left for non-ControlPersist connections is so
151: * error messages may be printed on the user's terminal.
1.239 djm 152: */
1.308 ! dtucker 153: if (!debug_flag && options.control_path != NULL &&
! 154: options.control_persist)
1.307 djm 155: stderr_null();
156:
1.239 djm 157: argv[0] = shell;
158: argv[1] = "-c";
159: argv[2] = command_string;
160: argv[3] = NULL;
161:
162: /*
163: * Execute the proxy command.
164: * Note that we gave up any extra privileges above.
165: */
166: execv(argv[0], argv);
167: perror(argv[0]);
168: exit(1);
169: }
170: /* Parent. */
171: if (pid < 0)
172: fatal("fork failed: %.100s", strerror(errno));
173: close(sp[0]);
174: free(command_string);
175:
176: if ((sock = mm_receive_fd(sp[1])) == -1)
177: fatal("proxy dialer did not pass back a connection");
1.271 markus 178: close(sp[1]);
1.239 djm 179:
180: while (waitpid(pid, NULL, 0) == -1)
181: if (errno != EINTR)
182: fatal("Couldn't wait for child: %s", strerror(errno));
183:
184: /* Set the connection file descriptors. */
1.286 djm 185: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
186: return -1; /* ssh_packet_set_connection logs error */
1.239 djm 187:
188: return 0;
189: }
190:
1.39 deraadt 191: /*
192: * Connect to the given ssh server using a proxy command.
193: */
1.109 itojun 194: static int
1.286 djm 195: ssh_proxy_connect(struct ssh *ssh, const char *host, u_short port,
196: const char *proxy_command)
1.1 deraadt 197: {
1.239 djm 198: char *command_string;
1.38 markus 199: int pin[2], pout[2];
1.69 deraadt 200: pid_t pid;
1.239 djm 201: char *shell;
1.237 markus 202:
1.226 djm 203: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 204: shell = _PATH_BSHELL;
1.38 markus 205:
206: /* Create pipes for communicating with the proxy. */
207: if (pipe(pin) < 0 || pipe(pout) < 0)
208: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 209: strerror(errno));
1.38 markus 210:
1.239 djm 211: command_string = expand_proxy_command(proxy_command, options.user,
212: host, port);
1.38 markus 213: debug("Executing proxy command: %.500s", command_string);
214:
215: /* Fork and execute the proxy command. */
216: if ((pid = fork()) == 0) {
217: char *argv[10];
218:
219: /* Redirect stdin and stdout. */
220: close(pin[1]);
221: if (pin[0] != 0) {
222: if (dup2(pin[0], 0) < 0)
223: perror("dup2 stdin");
224: close(pin[0]);
225: }
226: close(pout[0]);
227: if (dup2(pout[1], 1) < 0)
228: perror("dup2 stdout");
229: /* Cannot be 1 because pin allocated two descriptors. */
230: close(pout[1]);
231:
1.307 djm 232: /*
233: * Stderr is left for non-ControlPersist connections is so
234: * error messages may be printed on the user's terminal.
235: */
1.308 ! dtucker 236: if (!debug_flag && options.control_path != NULL &&
! 237: options.control_persist)
1.307 djm 238: stderr_null();
239:
1.201 djm 240: argv[0] = shell;
1.38 markus 241: argv[1] = "-c";
242: argv[2] = command_string;
243: argv[3] = NULL;
244:
245: /* Execute the proxy command. Note that we gave up any
246: extra privileges above. */
1.232 djm 247: signal(SIGPIPE, SIG_DFL);
1.89 markus 248: execv(argv[0], argv);
249: perror(argv[0]);
1.38 markus 250: exit(1);
251: }
252: /* Parent. */
253: if (pid < 0)
254: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 255: else
256: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 257:
258: /* Close child side of the descriptors. */
259: close(pin[0]);
260: close(pout[1]);
261:
262: /* Free the command name. */
1.238 djm 263: free(command_string);
1.38 markus 264:
265: /* Set the connection file descriptors. */
1.286 djm 266: if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
267: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 268:
1.110 markus 269: return 0;
1.227 djm 270: }
271:
272: void
273: ssh_kill_proxy_command(void)
274: {
275: /*
276: * Send SIGHUP to proxy command if used. We don't wait() in
277: * case it hangs and instead rely on init to reap the child
278: */
279: if (proxy_command_pid > 1)
1.228 djm 280: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 281: }
282:
1.39 deraadt 283: /*
1.295 djm 284: * Search a interface address list (returned from getifaddrs(3)) for an
1.298 djm 285: * address that matches the desired address family on the specified interface.
1.295 djm 286: * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure.
287: */
288: static int
289: check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs,
290: struct sockaddr_storage *resultp, socklen_t *rlenp)
291: {
292: struct sockaddr_in6 *sa6;
293: struct sockaddr_in *sa;
294: struct in6_addr *v6addr;
295: const struct ifaddrs *ifa;
296: int allow_local;
297:
298: /*
299: * Prefer addresses that are not loopback or linklocal, but use them
300: * if nothing else matches.
301: */
302: for (allow_local = 0; allow_local < 2; allow_local++) {
303: for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
304: if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL ||
305: (ifa->ifa_flags & IFF_UP) == 0 ||
306: ifa->ifa_addr->sa_family != af ||
307: strcmp(ifa->ifa_name, options.bind_interface) != 0)
308: continue;
309: switch (ifa->ifa_addr->sa_family) {
310: case AF_INET:
311: sa = (struct sockaddr_in *)ifa->ifa_addr;
312: if (!allow_local && sa->sin_addr.s_addr ==
313: htonl(INADDR_LOOPBACK))
314: continue;
315: if (*rlenp < sizeof(struct sockaddr_in)) {
316: error("%s: v4 addr doesn't fit",
317: __func__);
318: return -1;
319: }
320: *rlenp = sizeof(struct sockaddr_in);
321: memcpy(resultp, sa, *rlenp);
322: return 0;
323: case AF_INET6:
324: sa6 = (struct sockaddr_in6 *)ifa->ifa_addr;
325: v6addr = &sa6->sin6_addr;
326: if (!allow_local &&
327: (IN6_IS_ADDR_LINKLOCAL(v6addr) ||
328: IN6_IS_ADDR_LOOPBACK(v6addr)))
329: continue;
330: if (*rlenp < sizeof(struct sockaddr_in6)) {
331: error("%s: v6 addr doesn't fit",
332: __func__);
333: return -1;
334: }
335: *rlenp = sizeof(struct sockaddr_in6);
336: memcpy(resultp, sa6, *rlenp);
337: return 0;
338: }
339: }
340: }
341: return -1;
342: }
343:
344: /*
1.303 dtucker 345: * Creates a socket for use as the ssh connection.
1.39 deraadt 346: */
1.109 itojun 347: static int
1.302 dtucker 348: ssh_create_socket(struct addrinfo *ai)
1.1 deraadt 349: {
1.301 dtucker 350: int sock, r;
1.295 djm 351: struct sockaddr_storage bindaddr;
352: socklen_t bindaddrlen = 0;
1.246 djm 353: struct addrinfo hints, *res = NULL;
1.295 djm 354: struct ifaddrs *ifaddrs = NULL;
355: char ntop[NI_MAXHOST];
1.1 deraadt 356:
1.217 dtucker 357: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 358: if (sock < 0) {
1.240 djm 359: error("socket: %s", strerror(errno));
1.216 dtucker 360: return -1;
361: }
362: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 363:
364: /* Bind the socket to an alternative local IP address */
1.302 dtucker 365: if (options.bind_address == NULL && options.bind_interface == NULL)
1.105 markus 366: return sock;
367:
1.295 djm 368: if (options.bind_address != NULL) {
1.246 djm 369: memset(&hints, 0, sizeof(hints));
370: hints.ai_family = ai->ai_family;
371: hints.ai_socktype = ai->ai_socktype;
372: hints.ai_protocol = ai->ai_protocol;
373: hints.ai_flags = AI_PASSIVE;
1.295 djm 374: if ((r = getaddrinfo(options.bind_address, NULL,
375: &hints, &res)) != 0) {
1.246 djm 376: error("getaddrinfo: %s: %s", options.bind_address,
1.295 djm 377: ssh_gai_strerror(r));
378: goto fail;
379: }
1.296 dtucker 380: if (res == NULL) {
1.295 djm 381: error("getaddrinfo: no addrs");
382: goto fail;
383: }
384: memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
385: bindaddrlen = res->ai_addrlen;
386: } else if (options.bind_interface != NULL) {
387: if ((r = getifaddrs(&ifaddrs)) != 0) {
388: error("getifaddrs: %s: %s", options.bind_interface,
389: strerror(errno));
390: goto fail;
391: }
392: bindaddrlen = sizeof(bindaddr);
393: if (check_ifaddrs(options.bind_interface, ai->ai_family,
394: ifaddrs, &bindaddr, &bindaddrlen) != 0) {
395: logit("getifaddrs: %s: no suitable addresses",
396: options.bind_interface);
397: goto fail;
1.246 djm 398: }
1.105 markus 399: }
1.295 djm 400: if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
401: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
402: error("%s: getnameinfo failed: %s", __func__,
403: ssh_gai_strerror(r));
404: goto fail;
405: }
1.301 dtucker 406: if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
1.295 djm 407: error("bind %s: %s", ntop, strerror(errno));
408: goto fail;
1.38 markus 409: }
1.295 djm 410: debug("%s: bound to %s", __func__, ntop);
411: /* success */
412: goto out;
413: fail:
414: close(sock);
415: sock = -1;
416: out:
1.246 djm 417: if (res != NULL)
418: freeaddrinfo(res);
1.295 djm 419: if (ifaddrs != NULL)
420: freeifaddrs(ifaddrs);
1.38 markus 421: return sock;
1.1 deraadt 422: }
423:
1.282 djm 424: /*
425: * Wait up to *timeoutp milliseconds for fd to be readable. Updates
426: * *timeoutp with time remaining.
427: * Returns 0 if fd ready or -1 on timeout or error (see errno).
428: */
429: static int
430: waitrfd(int fd, int *timeoutp)
431: {
432: struct pollfd pfd;
433: struct timeval t_start;
434: int oerrno, r;
435:
1.288 dtucker 436: monotime_tv(&t_start);
1.282 djm 437: pfd.fd = fd;
438: pfd.events = POLLIN;
439: for (; *timeoutp >= 0;) {
440: r = poll(&pfd, 1, *timeoutp);
441: oerrno = errno;
442: ms_subtract_diff(&t_start, timeoutp);
443: errno = oerrno;
444: if (r > 0)
445: return 0;
446: else if (r == -1 && errno != EAGAIN)
447: return -1;
448: else if (r == 0)
449: break;
450: }
451: /* timeout */
452: errno = ETIMEDOUT;
453: return -1;
454: }
455:
1.141 djm 456: static int
457: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 458: socklen_t addrlen, int *timeoutp)
1.141 djm 459: {
1.282 djm 460: int optval = 0;
461: socklen_t optlen = sizeof(optval);
1.141 djm 462:
1.282 djm 463: /* No timeout: just do a blocking connect() */
464: if (*timeoutp <= 0)
465: return connect(sockfd, serv_addr, addrlen);
1.141 djm 466:
1.156 djm 467: set_nonblock(sockfd);
1.282 djm 468: if (connect(sockfd, serv_addr, addrlen) == 0) {
469: /* Succeeded already? */
1.156 djm 470: unset_nonblock(sockfd);
1.282 djm 471: return 0;
472: } else if (errno != EINPROGRESS)
473: return -1;
474:
475: if (waitrfd(sockfd, timeoutp) == -1)
476: return -1;
1.141 djm 477:
1.282 djm 478: /* Completed or failed */
479: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, &optlen) == -1) {
480: debug("getsockopt: %s", strerror(errno));
481: return -1;
1.141 djm 482: }
1.282 djm 483: if (optval != 0) {
484: errno = optval;
485: return -1;
1.202 djm 486: }
1.282 djm 487: unset_nonblock(sockfd);
488: return 0;
1.141 djm 489: }
490:
1.39 deraadt 491: /*
1.49 markus 492: * Opens a TCP/IP connection to the remote server on the given host.
493: * The address of the remote host will be returned in hostaddr.
1.302 dtucker 494: * If port is 0, the default port will be used.
1.39 deraadt 495: * Connection_attempts specifies the maximum number of tries (one per
496: * second). If proxy_command is non-NULL, it specifies the command (with %h
497: * and %p substituted for host and port, respectively) to use to contact
498: * the daemon.
499: */
1.241 djm 500: static int
1.286 djm 501: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.241 djm 502: struct sockaddr_storage *hostaddr, u_short port, int family,
1.302 dtucker 503: int connection_attempts, int *timeout_ms, int want_keepalive)
1.1 deraadt 504: {
1.90 markus 505: int on = 1;
1.290 djm 506: int oerrno, sock = -1, attempt;
1.90 markus 507: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 508: struct addrinfo *ai;
1.38 markus 509:
1.302 dtucker 510: debug2("%s", __func__);
1.268 djm 511: memset(ntop, 0, sizeof(ntop));
512: memset(strport, 0, sizeof(strport));
1.38 markus 513:
1.181 markus 514: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 515: if (attempt > 0) {
516: /* Sleep a moment before retrying. */
517: sleep(1);
1.38 markus 518: debug("Trying again...");
1.200 markus 519: }
1.181 markus 520: /*
521: * Loop through addresses for this host, and try each one in
522: * sequence until the connection succeeds.
523: */
1.49 markus 524: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 525: if (ai->ai_family != AF_INET &&
1.290 djm 526: ai->ai_family != AF_INET6) {
527: errno = EAFNOSUPPORT;
1.49 markus 528: continue;
1.290 djm 529: }
1.49 markus 530: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
531: ntop, sizeof(ntop), strport, sizeof(strport),
532: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.290 djm 533: oerrno = errno;
1.265 djm 534: error("%s: getnameinfo failed", __func__);
1.290 djm 535: errno = oerrno;
1.49 markus 536: continue;
537: }
538: debug("Connecting to %.200s [%.100s] port %s.",
539: host, ntop, strport);
540:
541: /* Create a socket for connecting. */
1.302 dtucker 542: sock = ssh_create_socket(ai);
1.292 stsp 543: if (sock < 0) {
1.110 markus 544: /* Any error is already output */
1.290 djm 545: errno = 0;
1.49 markus 546: continue;
1.292 stsp 547: }
1.49 markus 548:
1.141 djm 549: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 550: timeout_ms) >= 0) {
1.49 markus 551: /* Successful connection. */
1.102 markus 552: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 553: break;
1.49 markus 554: } else {
1.290 djm 555: oerrno = errno;
1.131 itojun 556: debug("connect to address %s port %s: %s",
557: ntop, strport, strerror(errno));
1.38 markus 558: close(sock);
1.181 markus 559: sock = -1;
1.290 djm 560: errno = oerrno;
1.38 markus 561: }
562: }
1.181 markus 563: if (sock != -1)
1.49 markus 564: break; /* Successful connection. */
1.38 markus 565: }
1.49 markus 566:
1.38 markus 567: /* Return failure if we didn't get a successful connection. */
1.181 markus 568: if (sock == -1) {
1.159 markus 569: error("ssh: connect to host %s port %s: %s",
1.290 djm 570: host, strport, errno == 0 ? "failure" : strerror(errno));
571: return -1;
1.130 itojun 572: }
1.38 markus 573:
574: debug("Connection established.");
1.90 markus 575:
1.155 markus 576: /* Set SO_KEEPALIVE if requested. */
1.202 djm 577: if (want_keepalive &&
1.90 markus 578: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
579: sizeof(on)) < 0)
580: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 581:
582: /* Set the connection. */
1.286 djm 583: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
584: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 585:
1.286 djm 586: return 0;
1.59 markus 587: }
588:
1.241 djm 589: int
1.286 djm 590: ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs,
1.241 djm 591: struct sockaddr_storage *hostaddr, u_short port, int family,
1.302 dtucker 592: int connection_attempts, int *timeout_ms, int want_keepalive)
1.241 djm 593: {
594: if (options.proxy_command == NULL) {
1.286 djm 595: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
1.302 dtucker 596: family, connection_attempts, timeout_ms, want_keepalive);
1.241 djm 597: } else if (strcmp(options.proxy_command, "-") == 0) {
1.286 djm 598: if ((ssh_packet_set_connection(ssh,
599: STDIN_FILENO, STDOUT_FILENO)) == NULL)
600: return -1; /* ssh_packet_set_connection logs error */
601: return 0;
1.241 djm 602: } else if (options.proxy_use_fdpass) {
1.286 djm 603: return ssh_proxy_fdpass_connect(ssh, host, port,
1.241 djm 604: options.proxy_command);
605: }
1.286 djm 606: return ssh_proxy_connect(ssh, host, port, options.proxy_command);
1.241 djm 607: }
608:
1.235 djm 609: static void
610: send_client_banner(int connection_out, int minor1)
611: {
612: /* Send our own protocol version identification. */
1.276 djm 613: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
614: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
1.270 markus 615: if (atomicio(vwrite, connection_out, client_version_string,
1.235 djm 616: strlen(client_version_string)) != strlen(client_version_string))
617: fatal("write: %.100s", strerror(errno));
618: chop(client_version_string);
619: debug("Local version string %.100s", client_version_string);
620: }
621:
1.43 markus 622: /*
1.39 deraadt 623: * Waits for the server identification string, and sends our own
624: * identification string.
625: */
1.213 andreas 626: void
1.202 djm 627: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 628: {
1.38 markus 629: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 630: int remote_major, remote_minor, mismatch;
1.38 markus 631: int connection_in = packet_get_connection_in();
632: int connection_out = packet_get_connection_out();
1.185 djm 633: u_int i, n;
1.202 djm 634: size_t len;
1.282 djm 635: int rc;
1.38 markus 636:
1.275 djm 637: send_client_banner(connection_out, 0);
1.235 djm 638:
1.163 avsm 639: /* Read other side's version identification. */
1.185 djm 640: for (n = 0;;) {
1.75 markus 641: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 642: if (timeout_ms > 0) {
1.282 djm 643: rc = waitrfd(connection_in, &timeout_ms);
644: if (rc == -1 && errno == ETIMEDOUT) {
1.202 djm 645: fatal("Connection timed out during "
646: "banner exchange");
1.282 djm 647: } else if (rc == -1) {
648: fatal("%s: %s",
649: __func__, strerror(errno));
1.202 djm 650: }
651: }
652:
1.270 markus 653: len = atomicio(read, connection_in, &buf[i], 1);
1.167 djm 654: if (len != 1 && errno == EPIPE)
1.202 djm 655: fatal("ssh_exchange_identification: "
656: "Connection closed by remote host");
1.163 avsm 657: else if (len != 1)
1.202 djm 658: fatal("ssh_exchange_identification: "
659: "read: %.100s", strerror(errno));
1.75 markus 660: if (buf[i] == '\r') {
661: buf[i] = '\n';
662: buf[i + 1] = 0;
663: continue; /**XXX wait for \n */
664: }
665: if (buf[i] == '\n') {
666: buf[i + 1] = 0;
667: break;
668: }
1.185 djm 669: if (++n > 65536)
1.202 djm 670: fatal("ssh_exchange_identification: "
671: "No banner received");
1.38 markus 672: }
1.75 markus 673: buf[sizeof(buf) - 1] = 0;
1.76 markus 674: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 675: break;
1.75 markus 676: debug("ssh_exchange_identification: %s", buf);
1.38 markus 677: }
1.59 markus 678: server_version_string = xstrdup(buf);
1.38 markus 679:
1.40 markus 680: /*
681: * Check that the versions match. In future this might accept
682: * several versions and set appropriate flags to handle them.
683: */
1.59 markus 684: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
685: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 686: fatal("Bad remote protocol version identification: '%.100s'", buf);
687: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 688: remote_major, remote_minor, remote_version);
1.38 markus 689:
1.255 markus 690: active_state->compat = compat_datafellows(remote_version);
1.64 markus 691: mismatch = 0;
1.59 markus 692:
1.116 deraadt 693: switch (remote_major) {
1.276 djm 694: case 2:
695: break;
1.64 markus 696: case 1:
1.276 djm 697: if (remote_minor != 99)
1.64 markus 698: mismatch = 1;
699: break;
1.68 markus 700: default:
1.64 markus 701: mismatch = 1;
702: break;
1.38 markus 703: }
1.64 markus 704: if (mismatch)
1.38 markus 705: fatal("Protocol major versions differ: %d vs. %d",
1.275 djm 706: PROTOCOL_MAJOR_2, remote_major);
1.243 djm 707: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
708: logit("Server version \"%.100s\" uses unsafe RSA signature "
709: "scheme; disabling use of RSA keys", remote_version);
1.59 markus 710: chop(server_version_string);
1.1 deraadt 711: }
712:
1.96 markus 713: /* defaults to 'no' */
1.109 itojun 714: static int
1.112 markus 715: confirm(const char *prompt)
1.1 deraadt 716: {
1.119 markus 717: const char *msg, *again = "Please type 'yes' or 'no': ";
718: char *p;
719: int ret = -1;
1.96 markus 720:
721: if (options.batch_mode)
722: return 0;
1.119 markus 723: for (msg = prompt;;msg = again) {
724: p = read_passphrase(msg, RP_ECHO);
1.289 djm 725: if (p == NULL)
726: return 0;
727: p[strcspn(p, "\n")] = '\0';
728: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 729: ret = 0;
1.289 djm 730: else if (strcasecmp(p, "yes") == 0)
1.119 markus 731: ret = 1;
1.238 djm 732: free(p);
1.119 markus 733: if (ret != -1)
734: return ret;
1.1 deraadt 735: }
736: }
737:
1.219 djm 738: static int
1.305 djm 739: check_host_cert(const char *host, const struct sshkey *key)
1.219 djm 740: {
741: const char *reason;
1.305 djm 742: int r;
1.219 djm 743:
1.305 djm 744: if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) {
1.219 djm 745: error("%s", reason);
746: return 0;
747: }
1.305 djm 748: if (sshbuf_len(key->cert->critical) != 0) {
1.223 djm 749: error("Certificate for %s contains unsupported "
750: "critical options(s)", host);
1.219 djm 751: return 0;
752: }
1.305 djm 753: if ((r = sshkey_check_cert_sigtype(key,
754: options.ca_sign_algorithms)) != 0) {
755: logit("%s: certificate signature algorithm %s: %s", __func__,
756: (key->cert == NULL || key->cert->signature_type == NULL) ?
757: "(null)" : key->cert->signature_type, ssh_err(r));
758: return 0;
759: }
760:
1.219 djm 761: return 1;
762: }
763:
1.229 djm 764: static int
765: sockaddr_is_local(struct sockaddr *hostaddr)
766: {
767: switch (hostaddr->sa_family) {
768: case AF_INET:
769: return (ntohl(((struct sockaddr_in *)hostaddr)->
770: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
771: case AF_INET6:
772: return IN6_IS_ADDR_LOOPBACK(
773: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
774: default:
775: return 0;
776: }
777: }
778:
779: /*
780: * Prepare the hostname and ip address strings that are used to lookup
781: * host keys in known_hosts files. These may have a port number appended.
782: */
783: void
784: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
785: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
786: {
787: char ntop[NI_MAXHOST];
788:
789: /*
790: * We don't have the remote ip-address for connections
791: * using a proxy command
792: */
793: if (hostfile_ipaddr != NULL) {
794: if (options.proxy_command == NULL) {
795: if (getnameinfo(hostaddr, hostaddr->sa_len,
796: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 797: fatal("%s: getnameinfo failed", __func__);
1.229 djm 798: *hostfile_ipaddr = put_host_port(ntop, port);
799: } else {
800: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
801: "command>");
802: }
803: }
804:
805: /*
806: * Allow the user to record the key under a different name or
807: * differentiate a non-standard port. This is useful for ssh
808: * tunneling over forwarded connections or if you run multiple
809: * sshd's on different ports on the same machine.
810: */
811: if (hostfile_hostname != NULL) {
812: if (options.host_key_alias != NULL) {
813: *hostfile_hostname = xstrdup(options.host_key_alias);
814: debug("using hostkeyalias: %s", *hostfile_hostname);
815: } else {
816: *hostfile_hostname = put_host_port(hostname, port);
817: }
818: }
819: }
820:
1.39 deraadt 821: /*
1.108 markus 822: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 823: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 824: */
1.197 dtucker 825: #define RDRW 0
826: #define RDONLY 1
827: #define ROQUIET 2
1.109 itojun 828: static int
1.197 dtucker 829: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 830: struct sshkey *host_key, int readonly,
1.234 djm 831: char **user_hostfiles, u_int num_user_hostfiles,
832: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 833: {
1.234 djm 834: HostStatus host_status;
835: HostStatus ip_status;
1.279 markus 836: struct sshkey *raw_key = NULL;
1.189 dtucker 837: char *ip = NULL, *host = NULL;
1.204 grunk 838: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 839: char msg[1024];
1.234 djm 840: const char *type;
841: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 842: int len, cancelled_forwarding = 0;
1.234 djm 843: int local = sockaddr_is_local(hostaddr);
1.280 markus 844: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 845: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 846: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 847: u_int i;
1.49 markus 848:
849: /*
850: * Force accepting of the host key for loopback/localhost. The
851: * problem is that if the home directory is NFS-mounted to multiple
852: * machines, localhost will refer to a different machine in each of
853: * them, and the user will get bogus HOST_CHANGED warnings. This
854: * essentially disables host authentication for localhost; however,
855: * this is probably not a real problem.
856: */
1.111 markus 857: if (options.no_host_authentication_for_localhost == 1 && local &&
858: options.host_key_alias == NULL) {
1.88 markus 859: debug("Forcing accepting of host key for "
860: "loopback/localhost.");
1.108 markus 861: return 0;
1.49 markus 862: }
1.42 markus 863:
864: /*
1.229 djm 865: * Prepare the hostname and address strings used for hostkey lookup.
866: * In some cases, these will have a port number appended.
1.42 markus 867: */
1.229 djm 868: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 869:
870: /*
1.88 markus 871: * Turn off check_host_ip if the connection is to localhost, via proxy
872: * command or if we don't have a hostname to compare with
873: */
1.189 dtucker 874: if (options.check_host_ip && (local ||
875: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 876: options.check_host_ip = 0;
1.86 markus 877:
1.229 djm 878: host_hostkeys = init_hostkeys();
1.234 djm 879: for (i = 0; i < num_user_hostfiles; i++)
880: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
881: for (i = 0; i < num_system_hostfiles; i++)
882: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 883:
884: ip_hostkeys = NULL;
885: if (!want_cert && options.check_host_ip) {
886: ip_hostkeys = init_hostkeys();
1.234 djm 887: for (i = 0; i < num_user_hostfiles; i++)
888: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
889: for (i = 0; i < num_system_hostfiles; i++)
890: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 891: }
1.38 markus 892:
1.219 djm 893: retry:
1.229 djm 894: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 895: want_cert = sshkey_is_cert(host_key);
896: type = sshkey_type(host_key);
1.219 djm 897:
1.46 markus 898: /*
1.170 djm 899: * Check if the host key is present in the user's list of known
1.40 markus 900: * hosts or in the systemwide list.
901: */
1.229 djm 902: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
903: &host_found);
904:
1.40 markus 905: /*
906: * Also perform check for the ip address, skip the check if we are
1.219 djm 907: * localhost, looking for a certificate, or the hostname was an ip
908: * address to begin with.
1.40 markus 909: */
1.229 djm 910: if (!want_cert && ip_hostkeys != NULL) {
911: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
912: &ip_found);
1.38 markus 913: if (host_status == HOST_CHANGED &&
1.229 djm 914: (ip_status != HOST_CHANGED ||
915: (ip_found != NULL &&
1.280 markus 916: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 917: host_ip_differ = 1;
918: } else
919: ip_status = host_status;
920:
921: switch (host_status) {
922: case HOST_OK:
923: /* The host is known and the key matches. */
1.219 djm 924: debug("Host '%.200s' is known and matches the %s host %s.",
925: host, type, want_cert ? "certificate" : "key");
1.229 djm 926: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
927: host_found->file, host_found->line);
1.281 djm 928: if (want_cert &&
929: !check_host_cert(options.host_key_alias == NULL ?
930: hostname : options.host_key_alias, host_key))
1.219 djm 931: goto fail;
1.88 markus 932: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 933: if (readonly || want_cert)
1.138 itojun 934: logit("%s host key for IP address "
1.108 markus 935: "'%.128s' not in list of known hosts.",
936: type, ip);
1.234 djm 937: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 938: host_key, options.hash_known_hosts))
1.138 itojun 939: logit("Failed to add the %s host key for IP "
1.108 markus 940: "address '%.128s' to the list of known "
1.262 dtucker 941: "hosts (%.500s).", type, ip,
1.234 djm 942: user_hostfiles[0]);
1.88 markus 943: else
1.138 itojun 944: logit("Warning: Permanently added the %s host "
1.108 markus 945: "key for IP address '%.128s' to the list "
946: "of known hosts.", type, ip);
1.209 grunk 947: } else if (options.visual_host_key) {
1.259 djm 948: fp = sshkey_fingerprint(host_key,
1.254 djm 949: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 950: ra = sshkey_fingerprint(host_key,
1.254 djm 951: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 952: if (fp == NULL || ra == NULL)
953: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 954: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 955: free(ra);
956: free(fp);
1.38 markus 957: }
1.257 djm 958: hostkey_trusted = 1;
1.38 markus 959: break;
960: case HOST_NEW:
1.197 dtucker 961: if (options.host_key_alias == NULL && port != 0 &&
962: port != SSH_DEFAULT_PORT) {
963: debug("checking without port identifier");
1.212 stevesk 964: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 965: ROQUIET, user_hostfiles, num_user_hostfiles,
966: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 967: debug("found matching key w/out port");
968: break;
969: }
970: }
1.219 djm 971: if (readonly || want_cert)
1.108 markus 972: goto fail;
1.38 markus 973: /* The host is new. */
1.285 djm 974: if (options.strict_host_key_checking ==
975: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 976: /*
977: * User has requested strict host key checking. We
978: * will not add the host key automatically. The only
979: * alternative left is to abort.
980: */
981: error("No %s host key is known for %.200s and you "
982: "have requested strict checking.", type, host);
983: goto fail;
1.285 djm 984: } else if (options.strict_host_key_checking ==
985: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 986: char msg1[1024], msg2[1024];
987:
1.229 djm 988: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 989: snprintf(msg1, sizeof(msg1),
1.168 djm 990: "\nbut keys of different type are already"
991: " known for this host.");
1.145 jakob 992: else
993: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 994: /* The default */
1.259 djm 995: fp = sshkey_fingerprint(host_key,
1.254 djm 996: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 997: ra = sshkey_fingerprint(host_key,
1.254 djm 998: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 999: if (fp == NULL || ra == NULL)
1000: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 1001: msg2[0] = '\0';
1002: if (options.verify_host_key_dns) {
1.153 jakob 1003: if (matching_host_key_dns)
1.145 jakob 1004: snprintf(msg2, sizeof(msg2),
1005: "Matching host key fingerprint"
1006: " found in DNS.\n");
1007: else
1008: snprintf(msg2, sizeof(msg2),
1009: "No matching host key fingerprint"
1010: " found in DNS.\n");
1011: }
1.119 markus 1012: snprintf(msg, sizeof(msg),
1.108 markus 1013: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 1014: "established%s\n"
1.209 grunk 1015: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 1016: "Are you sure you want to continue connecting "
1.132 markus 1017: "(yes/no)? ",
1.209 grunk 1018: host, ip, msg1, type, fp,
1019: options.visual_host_key ? "\n" : "",
1020: options.visual_host_key ? ra : "",
1021: msg2);
1.238 djm 1022: free(ra);
1023: free(fp);
1.119 markus 1024: if (!confirm(msg))
1.108 markus 1025: goto fail;
1.257 djm 1026: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 1027: }
1.161 djm 1028: /*
1.285 djm 1029: * If in "new" or "off" strict mode, add the key automatically
1030: * to the local known_hosts file.
1.161 djm 1031: */
1.88 markus 1032: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 1033: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 1034: hostp = hostline;
1.161 djm 1035: if (options.hash_known_hosts) {
1036: /* Add hash of host and IP separately */
1.234 djm 1037: r = add_host_to_hostfile(user_hostfiles[0],
1038: host, host_key, options.hash_known_hosts) &&
1039: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 1040: host_key, options.hash_known_hosts);
1041: } else {
1042: /* Add unhashed "host,ip" */
1.234 djm 1043: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 1044: hostline, host_key,
1045: options.hash_known_hosts);
1046: }
1047: } else {
1.234 djm 1048: r = add_host_to_hostfile(user_hostfiles[0], host,
1049: host_key, options.hash_known_hosts);
1.38 markus 1050: hostp = host;
1.161 djm 1051: }
1.38 markus 1052:
1.161 djm 1053: if (!r)
1.138 itojun 1054: logit("Failed to add the host to the list of known "
1.234 djm 1055: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 1056: else
1.138 itojun 1057: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 1058: "list of known hosts.", hostp, type);
1.38 markus 1059: break;
1.220 djm 1060: case HOST_REVOKED:
1061: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1062: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1063: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1064: error("The %s host key for %s is marked as revoked.", type, host);
1065: error("This could mean that a stolen key is being used to");
1066: error("impersonate this host.");
1067:
1068: /*
1069: * If strict host key checking is in use, the user will have
1070: * to edit the key manually and we can only abort.
1071: */
1.285 djm 1072: if (options.strict_host_key_checking !=
1073: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 1074: error("%s host key for %.200s was revoked and you have "
1075: "requested strict checking.", type, host);
1076: goto fail;
1077: }
1078: goto continue_unsafe;
1079:
1.38 markus 1080: case HOST_CHANGED:
1.219 djm 1081: if (want_cert) {
1082: /*
1083: * This is only a debug() since it is valid to have
1084: * CAs with wildcard DNS matches that don't match
1085: * all hosts that one might visit.
1086: */
1087: debug("Host certificate authority does not "
1.229 djm 1088: "match %s in %s:%lu", CA_MARKER,
1089: host_found->file, host_found->line);
1.219 djm 1090: goto fail;
1091: }
1.197 dtucker 1092: if (readonly == ROQUIET)
1093: goto fail;
1.38 markus 1094: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1095: char *key_msg;
1.38 markus 1096: if (ip_status == HOST_NEW)
1.158 avsm 1097: key_msg = "is unknown";
1.38 markus 1098: else if (ip_status == HOST_OK)
1.158 avsm 1099: key_msg = "is unchanged";
1.38 markus 1100: else
1.158 avsm 1101: key_msg = "has a different value";
1.38 markus 1102: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1103: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1104: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1105: error("The %s host key for %s has changed,", type, host);
1.208 ian 1106: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1107: error("%s. This could either mean that", key_msg);
1.38 markus 1108: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1109: error("and its host key have changed at the same time.");
1.88 markus 1110: if (ip_status != HOST_NEW)
1.229 djm 1111: error("Offending key for IP in %s:%lu",
1112: ip_found->file, ip_found->line);
1.38 markus 1113: }
1114: /* The host key has changed. */
1.150 jakob 1115: warn_changed_key(host_key);
1.38 markus 1116: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1117: user_hostfiles[0]);
1.280 markus 1118: error("Offending %s key in %s:%lu",
1119: sshkey_type(host_found->key),
1.229 djm 1120: host_found->file, host_found->line);
1.38 markus 1121:
1.40 markus 1122: /*
1123: * If strict host key checking is in use, the user will have
1124: * to edit the key manually and we can only abort.
1125: */
1.285 djm 1126: if (options.strict_host_key_checking !=
1127: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 1128: error("%s host key for %.200s has changed and you have "
1129: "requested strict checking.", type, host);
1130: goto fail;
1131: }
1.38 markus 1132:
1.220 djm 1133: continue_unsafe:
1.40 markus 1134: /*
1135: * If strict host key checking has not been requested, allow
1.144 djm 1136: * the connection but without MITM-able authentication or
1.194 stevesk 1137: * forwarding.
1.40 markus 1138: */
1.38 markus 1139: if (options.password_authentication) {
1.108 markus 1140: error("Password authentication is disabled to avoid "
1141: "man-in-the-middle attacks.");
1.38 markus 1142: options.password_authentication = 0;
1.210 dtucker 1143: cancelled_forwarding = 1;
1.144 djm 1144: }
1145: if (options.kbd_interactive_authentication) {
1146: error("Keyboard-interactive authentication is disabled"
1147: " to avoid man-in-the-middle attacks.");
1148: options.kbd_interactive_authentication = 0;
1149: options.challenge_response_authentication = 0;
1.210 dtucker 1150: cancelled_forwarding = 1;
1.144 djm 1151: }
1152: if (options.challenge_response_authentication) {
1153: error("Challenge/response authentication is disabled"
1154: " to avoid man-in-the-middle attacks.");
1155: options.challenge_response_authentication = 0;
1.210 dtucker 1156: cancelled_forwarding = 1;
1.38 markus 1157: }
1158: if (options.forward_agent) {
1.108 markus 1159: error("Agent forwarding is disabled to avoid "
1160: "man-in-the-middle attacks.");
1.38 markus 1161: options.forward_agent = 0;
1.210 dtucker 1162: cancelled_forwarding = 1;
1.83 markus 1163: }
1164: if (options.forward_x11) {
1.108 markus 1165: error("X11 forwarding is disabled to avoid "
1166: "man-in-the-middle attacks.");
1.83 markus 1167: options.forward_x11 = 0;
1.210 dtucker 1168: cancelled_forwarding = 1;
1.83 markus 1169: }
1.108 markus 1170: if (options.num_local_forwards > 0 ||
1171: options.num_remote_forwards > 0) {
1172: error("Port forwarding is disabled to avoid "
1173: "man-in-the-middle attacks.");
1174: options.num_local_forwards =
1.118 deraadt 1175: options.num_remote_forwards = 0;
1.210 dtucker 1176: cancelled_forwarding = 1;
1.194 stevesk 1177: }
1178: if (options.tun_open != SSH_TUNMODE_NO) {
1179: error("Tunnel forwarding is disabled to avoid "
1180: "man-in-the-middle attacks.");
1181: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1182: cancelled_forwarding = 1;
1.38 markus 1183: }
1.210 dtucker 1184: if (options.exit_on_forward_failure && cancelled_forwarding)
1185: fatal("Error: forwarding disabled due to host key "
1186: "check failure");
1187:
1.40 markus 1188: /*
1189: * XXX Should permit the user to change to use the new id.
1190: * This could be done by converting the host key to an
1191: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1192: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1193: * accept the authentication.
1194: */
1.38 markus 1195: break;
1.132 markus 1196: case HOST_FOUND:
1197: fatal("internal error");
1198: break;
1.88 markus 1199: }
1200:
1201: if (options.check_host_ip && host_status != HOST_CHANGED &&
1202: ip_status == HOST_CHANGED) {
1.119 markus 1203: snprintf(msg, sizeof(msg),
1204: "Warning: the %s host key for '%.200s' "
1205: "differs from the key for the IP address '%.128s'"
1.229 djm 1206: "\nOffending key for IP in %s:%lu",
1207: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1208: if (host_status == HOST_OK) {
1209: len = strlen(msg);
1210: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1211: "\nMatching host key in %s:%lu",
1212: host_found->file, host_found->line);
1.119 markus 1213: }
1.285 djm 1214: if (options.strict_host_key_checking ==
1215: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1216: strlcat(msg, "\nAre you sure you want "
1217: "to continue connecting (yes/no)? ", sizeof(msg));
1218: if (!confirm(msg))
1.108 markus 1219: goto fail;
1.285 djm 1220: } else if (options.strict_host_key_checking !=
1221: SSH_STRICT_HOSTKEY_OFF) {
1222: logit("%s", msg);
1223: error("Exiting, you have requested strict checking.");
1224: goto fail;
1.119 markus 1225: } else {
1.143 djm 1226: logit("%s", msg);
1.88 markus 1227: }
1.257 djm 1228: }
1229:
1230: if (!hostkey_trusted && options.update_hostkeys) {
1231: debug("%s: hostkey not known or explicitly trusted: "
1232: "disabling UpdateHostkeys", __func__);
1233: options.update_hostkeys = 0;
1.38 markus 1234: }
1.82 provos 1235:
1.238 djm 1236: free(ip);
1237: free(host);
1.229 djm 1238: if (host_hostkeys != NULL)
1239: free_hostkeys(host_hostkeys);
1240: if (ip_hostkeys != NULL)
1241: free_hostkeys(ip_hostkeys);
1.108 markus 1242: return 0;
1243:
1244: fail:
1.220 djm 1245: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1246: /*
1247: * No matching certificate. Downgrade cert to raw key and
1248: * search normally.
1249: */
1250: debug("No matching CA found. Retry with plain key");
1.280 markus 1251: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1252: fatal("%s: sshkey_from_private: %s",
1253: __func__, ssh_err(r));
1254: if ((r = sshkey_drop_cert(raw_key)) != 0)
1255: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1256: host_key = raw_key;
1257: goto retry;
1258: }
1.293 dtucker 1259: sshkey_free(raw_key);
1.238 djm 1260: free(ip);
1261: free(host);
1.229 djm 1262: if (host_hostkeys != NULL)
1263: free_hostkeys(host_hostkeys);
1264: if (ip_hostkeys != NULL)
1265: free_hostkeys(ip_hostkeys);
1.108 markus 1266: return -1;
1267: }
1268:
1.140 jakob 1269: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1270: int
1.279 markus 1271: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1272: {
1.267 djm 1273: u_int i;
1.250 djm 1274: int r = -1, flags = 0;
1.267 djm 1275: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1276: struct sshkey *plain = NULL;
1.229 djm 1277:
1.252 djm 1278: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1279: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1280: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1281: r = -1;
1282: goto out;
1283: }
1284:
1.267 djm 1285: if (sshkey_is_cert(host_key)) {
1286: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1287: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1288: error("%s: fingerprint CA key: %s",
1289: __func__, ssh_err(r));
1290: r = -1;
1291: goto out;
1292: }
1293: sshkey_format_cert_validity(host_key->cert,
1294: valid, sizeof(valid));
1295: debug("Server host certificate: %s %s, serial %llu "
1296: "ID \"%s\" CA %s %s valid %s",
1297: sshkey_ssh_name(host_key), fp,
1.269 djm 1298: (unsigned long long)host_key->cert->serial,
1299: host_key->cert->key_id,
1.267 djm 1300: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1301: valid);
1302: for (i = 0; i < host_key->cert->nprincipals; i++) {
1303: debug2("Server host certificate hostname: %s",
1304: host_key->cert->principals[i]);
1305: }
1306: } else {
1.276 djm 1307: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1308: }
1.252 djm 1309:
1310: if (sshkey_equal(previous_host_key, host_key)) {
1311: debug2("%s: server host key %s %s matches cached key",
1312: __func__, sshkey_type(host_key), fp);
1313: r = 0;
1314: goto out;
1315: }
1316:
1317: /* Check in RevokedHostKeys file if specified */
1318: if (options.revoked_host_keys != NULL) {
1319: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1320: switch (r) {
1321: case 0:
1322: break; /* not revoked */
1323: case SSH_ERR_KEY_REVOKED:
1324: error("Host key %s %s revoked by file %s",
1325: sshkey_type(host_key), fp,
1326: options.revoked_host_keys);
1327: r = -1;
1328: goto out;
1329: default:
1330: error("Error checking host key %s %s in "
1331: "revoked keys file %s: %s", sshkey_type(host_key),
1332: fp, options.revoked_host_keys, ssh_err(r));
1333: r = -1;
1334: goto out;
1335: }
1.250 djm 1336: }
1337:
1.247 djm 1338: if (options.verify_host_key_dns) {
1339: /*
1340: * XXX certs are not yet supported for DNS, so downgrade
1341: * them and try the plain key.
1342: */
1.252 djm 1343: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1344: goto out;
1345: if (sshkey_is_cert(plain))
1346: sshkey_drop_cert(plain);
1.247 djm 1347: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1348: if (flags & DNS_VERIFY_FOUND) {
1349: if (options.verify_host_key_dns == 1 &&
1350: flags & DNS_VERIFY_MATCH &&
1351: flags & DNS_VERIFY_SECURE) {
1.250 djm 1352: r = 0;
1.252 djm 1353: goto out;
1.247 djm 1354: }
1355: if (flags & DNS_VERIFY_MATCH) {
1356: matching_host_key_dns = 1;
1357: } else {
1.287 djm 1358: warn_changed_key(plain);
1359: error("Update the SSHFP RR in DNS "
1360: "with the new host key to get rid "
1361: "of this message.");
1.247 djm 1362: }
1.153 jakob 1363: }
1.140 jakob 1364: }
1365: }
1.250 djm 1366: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1367: options.user_hostfiles, options.num_user_hostfiles,
1368: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1369:
1.252 djm 1370: out:
1371: sshkey_free(plain);
1372: free(fp);
1.267 djm 1373: free(cafp);
1.250 djm 1374: if (r == 0 && host_key != NULL) {
1.280 markus 1375: sshkey_free(previous_host_key);
1376: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1377: }
1378:
1379: return r;
1.51 markus 1380: }
1.70 markus 1381:
1.51 markus 1382: /*
1383: * Starts a dialog with the server, and authenticates the current user on the
1384: * server. This does not need any extra privileges. The basic connection
1385: * to the server must already have been established before this is called.
1386: * If login fails, this function prints an error and never returns.
1387: * This function does not require super-user privileges.
1388: */
1389: void
1.120 markus 1390: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1391: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1392: {
1.241 djm 1393: char *host;
1.70 markus 1394: char *server_user, *local_user;
1395:
1396: local_user = xstrdup(pw->pw_name);
1397: server_user = options.user ? options.user : local_user;
1.51 markus 1398:
1399: /* Convert the user-supplied hostname into all lowercase. */
1400: host = xstrdup(orighost);
1.241 djm 1401: lowercase(host);
1.51 markus 1402:
1403: /* Exchange protocol version identification strings with the server. */
1.202 djm 1404: ssh_exchange_identification(timeout_ms);
1.51 markus 1405:
1406: /* Put the connection into non-blocking mode. */
1407: packet_set_nonblocking();
1408:
1409: /* key exchange */
1410: /* authenticate user */
1.261 dtucker 1411: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.276 djm 1412: ssh_kex2(host, hostaddr, port);
1413: ssh_userauth2(local_user, server_user, host, sensitive);
1.238 djm 1414: free(local_user);
1.97 markus 1415: }
1416:
1417: void
1418: ssh_put_password(char *password)
1419: {
1420: int size;
1421: char *padded;
1422:
1.99 deraadt 1423: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1424: packet_put_cstring(password);
1.99 deraadt 1425: return;
1426: }
1.272 deraadt 1427: size = ROUNDUP(strlen(password) + 1, 32);
1.179 djm 1428: padded = xcalloc(1, size);
1.97 markus 1429: strlcpy(padded, password, size);
1430: packet_put_string(padded, size);
1.245 djm 1431: explicit_bzero(padded, size);
1.238 djm 1432: free(padded);
1.132 markus 1433: }
1434:
1435: /* print all known host keys for a given host, but skip keys of given type */
1436: static int
1.279 markus 1437: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1438: {
1.242 djm 1439: int type[] = {
1440: KEY_RSA,
1441: KEY_DSA,
1442: KEY_ECDSA,
1443: KEY_ED25519,
1.297 markus 1444: KEY_XMSS,
1.242 djm 1445: -1
1446: };
1.229 djm 1447: int i, ret = 0;
1448: char *fp, *ra;
1449: const struct hostkey_entry *found;
1.132 markus 1450:
1451: for (i = 0; type[i] != -1; i++) {
1452: if (type[i] == key->type)
1453: continue;
1.229 djm 1454: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1455: continue;
1.259 djm 1456: fp = sshkey_fingerprint(found->key,
1.254 djm 1457: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1458: ra = sshkey_fingerprint(found->key,
1.254 djm 1459: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1460: if (fp == NULL || ra == NULL)
1461: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1462: logit("WARNING: %s key found for host %s\n"
1463: "in %s:%lu\n"
1464: "%s key fingerprint %s.",
1.300 markus 1465: sshkey_type(found->key),
1.229 djm 1466: found->host, found->file, found->line,
1.300 markus 1467: sshkey_type(found->key), fp);
1.229 djm 1468: if (options.visual_host_key)
1469: logit("%s", ra);
1.238 djm 1470: free(ra);
1471: free(fp);
1.229 djm 1472: ret = 1;
1.132 markus 1473: }
1.229 djm 1474: return ret;
1.150 jakob 1475: }
1476:
1477: static void
1.279 markus 1478: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1479: {
1480: char *fp;
1481:
1.259 djm 1482: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1483: SSH_FP_DEFAULT);
1.259 djm 1484: if (fp == NULL)
1485: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1486:
1487: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1488: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1489: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1490: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1491: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1492: error("It is also possible that a host key has just been changed.");
1.150 jakob 1493: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.300 markus 1494: sshkey_type(host_key), fp);
1.150 jakob 1495: error("Please contact your system administrator.");
1496:
1.238 djm 1497: free(fp);
1.171 reyk 1498: }
1499:
1500: /*
1501: * Execute a local command
1502: */
1503: int
1504: ssh_local_cmd(const char *args)
1505: {
1506: char *shell;
1507: pid_t pid;
1508: int status;
1.231 djm 1509: void (*osighand)(int);
1.171 reyk 1510:
1511: if (!options.permit_local_command ||
1512: args == NULL || !*args)
1513: return (1);
1514:
1.226 djm 1515: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1516: shell = _PATH_BSHELL;
1517:
1.231 djm 1518: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1519: pid = fork();
1520: if (pid == 0) {
1.232 djm 1521: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1522: debug3("Executing %s -c \"%s\"", shell, args);
1523: execl(shell, shell, "-c", args, (char *)NULL);
1524: error("Couldn't execute %s -c \"%s\": %s",
1525: shell, args, strerror(errno));
1526: _exit(1);
1527: } else if (pid == -1)
1528: fatal("fork failed: %.100s", strerror(errno));
1529: while (waitpid(pid, &status, 0) == -1)
1530: if (errno != EINTR)
1531: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1532: signal(SIGCHLD, osighand);
1.171 reyk 1533:
1534: if (!WIFEXITED(status))
1535: return (1);
1536:
1537: return (WEXITSTATUS(status));
1.266 jcs 1538: }
1539:
1540: void
1.294 djm 1541: maybe_add_key_to_agent(char *authfile, const struct sshkey *private,
1542: char *comment, char *passphrase)
1.266 jcs 1543: {
1544: int auth_sock = -1, r;
1545:
1546: if (options.add_keys_to_agent == 0)
1547: return;
1548:
1549: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1550: debug3("no authentication agent, not adding key");
1551: return;
1552: }
1553:
1554: if (options.add_keys_to_agent == 2 &&
1555: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1556: debug3("user denied adding this key");
1.273 dtucker 1557: close(auth_sock);
1.266 jcs 1558: return;
1559: }
1560:
1561: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1.297 markus 1562: (options.add_keys_to_agent == 3), 0)) == 0)
1.266 jcs 1563: debug("identity added to agent: %s", authfile);
1564: else
1565: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1566: close(auth_sock);
1.1 deraadt 1567: }
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