Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.295
1.295 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.294 2018/02/10 09:25:35 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"
1.59 markus 41: #include "buffer.h"
1.1 deraadt 42: #include "packet.h"
43: #include "uidswap.h"
1.21 markus 44: #include "compat.h"
1.58 markus 45: #include "key.h"
1.71 markus 46: #include "sshconnect.h"
1.58 markus 47: #include "hostfile.h"
1.91 markus 48: #include "log.h"
1.251 millert 49: #include "misc.h"
1.91 markus 50: #include "readconf.h"
51: #include "atomicio.h"
1.140 jakob 52: #include "dns.h"
1.239 djm 53: #include "monitor_fdpass.h"
1.219 djm 54: #include "ssh2.h"
1.186 stevesk 55: #include "version.h"
1.252 djm 56: #include "authfile.h"
57: #include "ssherr.h"
1.266 jcs 58: #include "authfd.h"
1.140 jakob 59:
1.70 markus 60: char *client_version_string = NULL;
61: char *server_version_string = NULL;
1.279 markus 62: struct sshkey *previous_host_key = NULL;
1.59 markus 63:
1.169 stevesk 64: static int matching_host_key_dns = 0;
1.145 jakob 65:
1.227 djm 66: static pid_t proxy_command_pid = 0;
67:
1.124 markus 68: /* import */
1.43 markus 69: extern Options options;
1.50 markus 70: extern char *__progname;
1.124 markus 71: extern uid_t original_real_uid;
72: extern uid_t original_effective_uid;
1.91 markus 73:
1.279 markus 74: static int show_other_keys(struct hostkeys *, struct sshkey *);
75: static void warn_changed_key(struct sshkey *);
1.132 markus 76:
1.239 djm 77: /* Expand a proxy command */
78: static char *
79: expand_proxy_command(const char *proxy_command, const char *user,
80: const char *host, int port)
81: {
82: char *tmp, *ret, strport[NI_MAXSERV];
83:
1.241 djm 84: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 85: xasprintf(&tmp, "exec %s", proxy_command);
86: ret = percent_expand(tmp, "h", host, "p", strport,
87: "r", options.user, (char *)NULL);
88: free(tmp);
89: return ret;
90: }
91:
92: /*
93: * Connect to the given ssh server using a proxy command that passes a
94: * a connected fd back to us.
95: */
96: static int
1.286 djm 97: ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, u_short port,
1.239 djm 98: const char *proxy_command)
99: {
100: char *command_string;
101: int sp[2], sock;
102: pid_t pid;
103: char *shell;
104:
105: if ((shell = getenv("SHELL")) == NULL)
106: shell = _PATH_BSHELL;
107:
108: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
109: fatal("Could not create socketpair to communicate with "
110: "proxy dialer: %.100s", strerror(errno));
111:
112: command_string = expand_proxy_command(proxy_command, options.user,
113: host, port);
114: debug("Executing proxy dialer command: %.500s", command_string);
115:
116: /* Fork and execute the proxy command. */
117: if ((pid = fork()) == 0) {
118: char *argv[10];
119:
120: /* Child. Permanently give up superuser privileges. */
121: permanently_drop_suid(original_real_uid);
122:
123: close(sp[1]);
124: /* Redirect stdin and stdout. */
125: if (sp[0] != 0) {
126: if (dup2(sp[0], 0) < 0)
127: perror("dup2 stdin");
128: }
129: if (sp[0] != 1) {
130: if (dup2(sp[0], 1) < 0)
131: perror("dup2 stdout");
132: }
133: if (sp[0] >= 2)
134: close(sp[0]);
135:
136: /*
137: * Stderr is left as it is so that error messages get
138: * printed on the user's terminal.
139: */
140: argv[0] = shell;
141: argv[1] = "-c";
142: argv[2] = command_string;
143: argv[3] = NULL;
144:
145: /*
146: * Execute the proxy command.
147: * Note that we gave up any extra privileges above.
148: */
149: execv(argv[0], argv);
150: perror(argv[0]);
151: exit(1);
152: }
153: /* Parent. */
154: if (pid < 0)
155: fatal("fork failed: %.100s", strerror(errno));
156: close(sp[0]);
157: free(command_string);
158:
159: if ((sock = mm_receive_fd(sp[1])) == -1)
160: fatal("proxy dialer did not pass back a connection");
1.271 markus 161: close(sp[1]);
1.239 djm 162:
163: while (waitpid(pid, NULL, 0) == -1)
164: if (errno != EINTR)
165: fatal("Couldn't wait for child: %s", strerror(errno));
166:
167: /* Set the connection file descriptors. */
1.286 djm 168: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
169: return -1; /* ssh_packet_set_connection logs error */
1.239 djm 170:
171: return 0;
172: }
173:
1.39 deraadt 174: /*
175: * Connect to the given ssh server using a proxy command.
176: */
1.109 itojun 177: static int
1.286 djm 178: ssh_proxy_connect(struct ssh *ssh, const char *host, u_short port,
179: const char *proxy_command)
1.1 deraadt 180: {
1.239 djm 181: char *command_string;
1.38 markus 182: int pin[2], pout[2];
1.69 deraadt 183: pid_t pid;
1.239 djm 184: char *shell;
1.237 markus 185:
1.226 djm 186: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 187: shell = _PATH_BSHELL;
1.38 markus 188:
189: /* Create pipes for communicating with the proxy. */
190: if (pipe(pin) < 0 || pipe(pout) < 0)
191: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 192: strerror(errno));
1.38 markus 193:
1.239 djm 194: command_string = expand_proxy_command(proxy_command, options.user,
195: host, port);
1.38 markus 196: debug("Executing proxy command: %.500s", command_string);
197:
198: /* Fork and execute the proxy command. */
199: if ((pid = fork()) == 0) {
200: char *argv[10];
201:
202: /* Child. Permanently give up superuser privileges. */
1.184 markus 203: permanently_drop_suid(original_real_uid);
1.38 markus 204:
205: /* Redirect stdin and stdout. */
206: close(pin[1]);
207: if (pin[0] != 0) {
208: if (dup2(pin[0], 0) < 0)
209: perror("dup2 stdin");
210: close(pin[0]);
211: }
212: close(pout[0]);
213: if (dup2(pout[1], 1) < 0)
214: perror("dup2 stdout");
215: /* Cannot be 1 because pin allocated two descriptors. */
216: close(pout[1]);
217:
218: /* Stderr is left as it is so that error messages get
219: printed on the user's terminal. */
1.201 djm 220: argv[0] = shell;
1.38 markus 221: argv[1] = "-c";
222: argv[2] = command_string;
223: argv[3] = NULL;
224:
225: /* Execute the proxy command. Note that we gave up any
226: extra privileges above. */
1.232 djm 227: signal(SIGPIPE, SIG_DFL);
1.89 markus 228: execv(argv[0], argv);
229: perror(argv[0]);
1.38 markus 230: exit(1);
231: }
232: /* Parent. */
233: if (pid < 0)
234: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 235: else
236: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 237:
238: /* Close child side of the descriptors. */
239: close(pin[0]);
240: close(pout[1]);
241:
242: /* Free the command name. */
1.238 djm 243: free(command_string);
1.38 markus 244:
245: /* Set the connection file descriptors. */
1.286 djm 246: if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
247: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 248:
1.110 markus 249: return 0;
1.227 djm 250: }
251:
252: void
253: ssh_kill_proxy_command(void)
254: {
255: /*
256: * Send SIGHUP to proxy command if used. We don't wait() in
257: * case it hangs and instead rely on init to reap the child
258: */
259: if (proxy_command_pid > 1)
1.228 djm 260: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 261: }
262:
1.39 deraadt 263: /*
1.295 ! djm 264: * Search a interface address list (returned from getifaddrs(3)) for an
! 265: * address that matches the desired address family on the specifed interface.
! 266: * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure.
! 267: */
! 268: static int
! 269: check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs,
! 270: struct sockaddr_storage *resultp, socklen_t *rlenp)
! 271: {
! 272: struct sockaddr_in6 *sa6;
! 273: struct sockaddr_in *sa;
! 274: struct in6_addr *v6addr;
! 275: const struct ifaddrs *ifa;
! 276: int allow_local;
! 277:
! 278: /*
! 279: * Prefer addresses that are not loopback or linklocal, but use them
! 280: * if nothing else matches.
! 281: */
! 282: for (allow_local = 0; allow_local < 2; allow_local++) {
! 283: for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
! 284: if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL ||
! 285: (ifa->ifa_flags & IFF_UP) == 0 ||
! 286: ifa->ifa_addr->sa_family != af ||
! 287: strcmp(ifa->ifa_name, options.bind_interface) != 0)
! 288: continue;
! 289: switch (ifa->ifa_addr->sa_family) {
! 290: case AF_INET:
! 291: sa = (struct sockaddr_in *)ifa->ifa_addr;
! 292: if (!allow_local && sa->sin_addr.s_addr ==
! 293: htonl(INADDR_LOOPBACK))
! 294: continue;
! 295: if (*rlenp < sizeof(struct sockaddr_in)) {
! 296: error("%s: v4 addr doesn't fit",
! 297: __func__);
! 298: return -1;
! 299: }
! 300: *rlenp = sizeof(struct sockaddr_in);
! 301: memcpy(resultp, sa, *rlenp);
! 302: return 0;
! 303: case AF_INET6:
! 304: sa6 = (struct sockaddr_in6 *)ifa->ifa_addr;
! 305: v6addr = &sa6->sin6_addr;
! 306: if (!allow_local &&
! 307: (IN6_IS_ADDR_LINKLOCAL(v6addr) ||
! 308: IN6_IS_ADDR_LOOPBACK(v6addr)))
! 309: continue;
! 310: if (*rlenp < sizeof(struct sockaddr_in6)) {
! 311: error("%s: v6 addr doesn't fit",
! 312: __func__);
! 313: return -1;
! 314: }
! 315: *rlenp = sizeof(struct sockaddr_in6);
! 316: memcpy(resultp, sa6, *rlenp);
! 317: return 0;
! 318: }
! 319: }
! 320: }
! 321: return -1;
! 322: }
! 323:
! 324: /*
1.39 deraadt 325: * Creates a (possibly privileged) socket for use as the ssh connection.
326: */
1.109 itojun 327: static int
1.139 markus 328: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 329: {
1.295 ! djm 330: int sock, r, oerrno;
! 331: struct sockaddr_storage bindaddr;
! 332: socklen_t bindaddrlen = 0;
1.246 djm 333: struct addrinfo hints, *res = NULL;
1.295 ! djm 334: struct ifaddrs *ifaddrs = NULL;
! 335: char ntop[NI_MAXHOST];
1.1 deraadt 336:
1.217 dtucker 337: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 338: if (sock < 0) {
1.240 djm 339: error("socket: %s", strerror(errno));
1.216 dtucker 340: return -1;
341: }
342: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 343:
344: /* Bind the socket to an alternative local IP address */
1.295 ! djm 345: if (options.bind_address == NULL && options.bind_interface == NULL &&
! 346: !privileged)
1.105 markus 347: return sock;
348:
1.295 ! djm 349: if (options.bind_address != NULL) {
1.246 djm 350: memset(&hints, 0, sizeof(hints));
351: hints.ai_family = ai->ai_family;
352: hints.ai_socktype = ai->ai_socktype;
353: hints.ai_protocol = ai->ai_protocol;
354: hints.ai_flags = AI_PASSIVE;
1.295 ! djm 355: if ((r = getaddrinfo(options.bind_address, NULL,
! 356: &hints, &res)) != 0) {
1.246 djm 357: error("getaddrinfo: %s: %s", options.bind_address,
1.295 ! djm 358: ssh_gai_strerror(r));
! 359: goto fail;
! 360: }
! 361: if (res == NULL)
! 362: error("getaddrinfo: no addrs");
! 363: goto fail;
! 364: if (res->ai_addrlen > sizeof(bindaddr)) {
! 365: error("%s: addr doesn't fit", __func__);
! 366: goto fail;
! 367: }
! 368: memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
! 369: bindaddrlen = res->ai_addrlen;
! 370: } else if (options.bind_interface != NULL) {
! 371: if ((r = getifaddrs(&ifaddrs)) != 0) {
! 372: error("getifaddrs: %s: %s", options.bind_interface,
! 373: strerror(errno));
! 374: goto fail;
! 375: }
! 376: bindaddrlen = sizeof(bindaddr);
! 377: if (check_ifaddrs(options.bind_interface, ai->ai_family,
! 378: ifaddrs, &bindaddr, &bindaddrlen) != 0) {
! 379: logit("getifaddrs: %s: no suitable addresses",
! 380: options.bind_interface);
! 381: goto fail;
1.246 djm 382: }
1.105 markus 383: }
1.295 ! djm 384: if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
! 385: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
! 386: error("%s: getnameinfo failed: %s", __func__,
! 387: ssh_gai_strerror(r));
! 388: goto fail;
! 389: }
1.240 djm 390: /*
391: * If we are running as root and want to connect to a privileged
392: * port, bind our own socket to a privileged port.
393: */
394: if (privileged) {
395: PRIV_START;
1.295 ! djm 396: r = bindresvport_sa(sock,
! 397: bindaddrlen == 0 ? NULL : (struct sockaddr *)&bindaddr);
! 398: oerrno = errno;
1.240 djm 399: PRIV_END;
400: if (r < 0) {
1.295 ! djm 401: error("bindresvport_sa %s: %s", ntop,
! 402: strerror(oerrno));
1.240 djm 403: goto fail;
404: }
1.295 ! djm 405: } else if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
! 406: error("bind %s: %s", ntop, strerror(errno));
! 407: goto fail;
1.38 markus 408: }
1.295 ! djm 409: debug("%s: bound to %s", __func__, ntop);
! 410: /* success */
! 411: goto out;
! 412: fail:
! 413: close(sock);
! 414: sock = -1;
! 415: out:
1.246 djm 416: if (res != NULL)
417: freeaddrinfo(res);
1.295 ! djm 418: if (ifaddrs != NULL)
! 419: freeifaddrs(ifaddrs);
1.38 markus 420: return sock;
1.1 deraadt 421: }
422:
1.282 djm 423: /*
424: * Wait up to *timeoutp milliseconds for fd to be readable. Updates
425: * *timeoutp with time remaining.
426: * Returns 0 if fd ready or -1 on timeout or error (see errno).
427: */
428: static int
429: waitrfd(int fd, int *timeoutp)
430: {
431: struct pollfd pfd;
432: struct timeval t_start;
433: int oerrno, r;
434:
1.288 dtucker 435: monotime_tv(&t_start);
1.282 djm 436: pfd.fd = fd;
437: pfd.events = POLLIN;
438: for (; *timeoutp >= 0;) {
439: r = poll(&pfd, 1, *timeoutp);
440: oerrno = errno;
441: ms_subtract_diff(&t_start, timeoutp);
442: errno = oerrno;
443: if (r > 0)
444: return 0;
445: else if (r == -1 && errno != EAGAIN)
446: return -1;
447: else if (r == 0)
448: break;
449: }
450: /* timeout */
451: errno = ETIMEDOUT;
452: return -1;
453: }
454:
1.141 djm 455: static int
456: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 457: socklen_t addrlen, int *timeoutp)
1.141 djm 458: {
1.282 djm 459: int optval = 0;
460: socklen_t optlen = sizeof(optval);
1.141 djm 461:
1.282 djm 462: /* No timeout: just do a blocking connect() */
463: if (*timeoutp <= 0)
464: return connect(sockfd, serv_addr, addrlen);
1.141 djm 465:
1.156 djm 466: set_nonblock(sockfd);
1.282 djm 467: if (connect(sockfd, serv_addr, addrlen) == 0) {
468: /* Succeeded already? */
1.156 djm 469: unset_nonblock(sockfd);
1.282 djm 470: return 0;
471: } else if (errno != EINPROGRESS)
472: return -1;
473:
474: if (waitrfd(sockfd, timeoutp) == -1)
475: return -1;
1.141 djm 476:
1.282 djm 477: /* Completed or failed */
478: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, &optlen) == -1) {
479: debug("getsockopt: %s", strerror(errno));
480: return -1;
1.141 djm 481: }
1.282 djm 482: if (optval != 0) {
483: errno = optval;
484: return -1;
1.202 djm 485: }
1.282 djm 486: unset_nonblock(sockfd);
487: return 0;
1.141 djm 488: }
489:
1.39 deraadt 490: /*
1.49 markus 491: * Opens a TCP/IP connection to the remote server on the given host.
492: * The address of the remote host will be returned in hostaddr.
1.124 markus 493: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 494: * a privileged port will be allocated to make the connection.
1.124 markus 495: * This requires super-user privileges if needpriv is true.
1.39 deraadt 496: * Connection_attempts specifies the maximum number of tries (one per
497: * second). If proxy_command is non-NULL, it specifies the command (with %h
498: * and %p substituted for host and port, respectively) to use to contact
499: * the daemon.
500: */
1.241 djm 501: static int
1.286 djm 502: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.241 djm 503: struct sockaddr_storage *hostaddr, u_short port, int family,
504: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
1.1 deraadt 505: {
1.90 markus 506: int on = 1;
1.290 djm 507: int oerrno, sock = -1, attempt;
1.90 markus 508: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 509: struct addrinfo *ai;
1.38 markus 510:
1.265 djm 511: debug2("%s: needpriv %d", __func__, needpriv);
1.268 djm 512: memset(ntop, 0, sizeof(ntop));
513: memset(strport, 0, sizeof(strport));
1.38 markus 514:
1.181 markus 515: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 516: if (attempt > 0) {
517: /* Sleep a moment before retrying. */
518: sleep(1);
1.38 markus 519: debug("Trying again...");
1.200 markus 520: }
1.181 markus 521: /*
522: * Loop through addresses for this host, and try each one in
523: * sequence until the connection succeeds.
524: */
1.49 markus 525: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 526: if (ai->ai_family != AF_INET &&
1.290 djm 527: ai->ai_family != AF_INET6) {
528: errno = EAFNOSUPPORT;
1.49 markus 529: continue;
1.290 djm 530: }
1.49 markus 531: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
532: ntop, sizeof(ntop), strport, sizeof(strport),
533: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.290 djm 534: oerrno = errno;
1.265 djm 535: error("%s: getnameinfo failed", __func__);
1.290 djm 536: errno = oerrno;
1.49 markus 537: continue;
538: }
539: debug("Connecting to %.200s [%.100s] port %s.",
540: host, ntop, strport);
541:
542: /* Create a socket for connecting. */
1.139 markus 543: sock = ssh_create_socket(needpriv, ai);
1.292 stsp 544: if (sock < 0) {
1.110 markus 545: /* Any error is already output */
1.290 djm 546: errno = 0;
1.49 markus 547: continue;
1.292 stsp 548: }
1.49 markus 549:
1.141 djm 550: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 551: timeout_ms) >= 0) {
1.49 markus 552: /* Successful connection. */
1.102 markus 553: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 554: break;
1.49 markus 555: } else {
1.290 djm 556: oerrno = errno;
1.131 itojun 557: debug("connect to address %s port %s: %s",
558: ntop, strport, strerror(errno));
1.38 markus 559: close(sock);
1.181 markus 560: sock = -1;
1.290 djm 561: errno = oerrno;
1.38 markus 562: }
563: }
1.181 markus 564: if (sock != -1)
1.49 markus 565: break; /* Successful connection. */
1.38 markus 566: }
1.49 markus 567:
1.38 markus 568: /* Return failure if we didn't get a successful connection. */
1.181 markus 569: if (sock == -1) {
1.159 markus 570: error("ssh: connect to host %s port %s: %s",
1.290 djm 571: host, strport, errno == 0 ? "failure" : strerror(errno));
572: return -1;
1.130 itojun 573: }
1.38 markus 574:
575: debug("Connection established.");
1.90 markus 576:
1.155 markus 577: /* Set SO_KEEPALIVE if requested. */
1.202 djm 578: if (want_keepalive &&
1.90 markus 579: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
580: sizeof(on)) < 0)
581: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 582:
583: /* Set the connection. */
1.286 djm 584: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
585: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 586:
1.286 djm 587: return 0;
1.59 markus 588: }
589:
1.241 djm 590: int
1.286 djm 591: ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs,
1.241 djm 592: struct sockaddr_storage *hostaddr, u_short port, int family,
593: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
594: {
595: if (options.proxy_command == NULL) {
1.286 djm 596: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
597: family, connection_attempts, timeout_ms, want_keepalive,
598: needpriv);
1.241 djm 599: } else if (strcmp(options.proxy_command, "-") == 0) {
1.286 djm 600: if ((ssh_packet_set_connection(ssh,
601: STDIN_FILENO, STDOUT_FILENO)) == NULL)
602: return -1; /* ssh_packet_set_connection logs error */
603: return 0;
1.241 djm 604: } else if (options.proxy_use_fdpass) {
1.286 djm 605: return ssh_proxy_fdpass_connect(ssh, host, port,
1.241 djm 606: options.proxy_command);
607: }
1.286 djm 608: return ssh_proxy_connect(ssh, host, port, options.proxy_command);
1.241 djm 609: }
610:
1.235 djm 611: static void
612: send_client_banner(int connection_out, int minor1)
613: {
614: /* Send our own protocol version identification. */
1.276 djm 615: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
616: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
1.270 markus 617: if (atomicio(vwrite, connection_out, client_version_string,
1.235 djm 618: strlen(client_version_string)) != strlen(client_version_string))
619: fatal("write: %.100s", strerror(errno));
620: chop(client_version_string);
621: debug("Local version string %.100s", client_version_string);
622: }
623:
1.43 markus 624: /*
1.39 deraadt 625: * Waits for the server identification string, and sends our own
626: * identification string.
627: */
1.213 andreas 628: void
1.202 djm 629: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 630: {
1.38 markus 631: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 632: int remote_major, remote_minor, mismatch;
1.38 markus 633: int connection_in = packet_get_connection_in();
634: int connection_out = packet_get_connection_out();
1.185 djm 635: u_int i, n;
1.202 djm 636: size_t len;
1.282 djm 637: int rc;
1.38 markus 638:
1.275 djm 639: send_client_banner(connection_out, 0);
1.235 djm 640:
1.163 avsm 641: /* Read other side's version identification. */
1.185 djm 642: for (n = 0;;) {
1.75 markus 643: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 644: if (timeout_ms > 0) {
1.282 djm 645: rc = waitrfd(connection_in, &timeout_ms);
646: if (rc == -1 && errno == ETIMEDOUT) {
1.202 djm 647: fatal("Connection timed out during "
648: "banner exchange");
1.282 djm 649: } else if (rc == -1) {
650: fatal("%s: %s",
651: __func__, strerror(errno));
1.202 djm 652: }
653: }
654:
1.270 markus 655: len = atomicio(read, connection_in, &buf[i], 1);
1.167 djm 656: if (len != 1 && errno == EPIPE)
1.202 djm 657: fatal("ssh_exchange_identification: "
658: "Connection closed by remote host");
1.163 avsm 659: else if (len != 1)
1.202 djm 660: fatal("ssh_exchange_identification: "
661: "read: %.100s", strerror(errno));
1.75 markus 662: if (buf[i] == '\r') {
663: buf[i] = '\n';
664: buf[i + 1] = 0;
665: continue; /**XXX wait for \n */
666: }
667: if (buf[i] == '\n') {
668: buf[i + 1] = 0;
669: break;
670: }
1.185 djm 671: if (++n > 65536)
1.202 djm 672: fatal("ssh_exchange_identification: "
673: "No banner received");
1.38 markus 674: }
1.75 markus 675: buf[sizeof(buf) - 1] = 0;
1.76 markus 676: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 677: break;
1.75 markus 678: debug("ssh_exchange_identification: %s", buf);
1.38 markus 679: }
1.59 markus 680: server_version_string = xstrdup(buf);
1.38 markus 681:
1.40 markus 682: /*
683: * Check that the versions match. In future this might accept
684: * several versions and set appropriate flags to handle them.
685: */
1.59 markus 686: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
687: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 688: fatal("Bad remote protocol version identification: '%.100s'", buf);
689: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 690: remote_major, remote_minor, remote_version);
1.38 markus 691:
1.255 markus 692: active_state->compat = compat_datafellows(remote_version);
1.64 markus 693: mismatch = 0;
1.59 markus 694:
1.116 deraadt 695: switch (remote_major) {
1.276 djm 696: case 2:
697: break;
1.64 markus 698: case 1:
1.276 djm 699: if (remote_minor != 99)
1.64 markus 700: mismatch = 1;
701: break;
1.68 markus 702: default:
1.64 markus 703: mismatch = 1;
704: break;
1.38 markus 705: }
1.64 markus 706: if (mismatch)
1.38 markus 707: fatal("Protocol major versions differ: %d vs. %d",
1.275 djm 708: PROTOCOL_MAJOR_2, remote_major);
1.243 djm 709: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
710: logit("Server version \"%.100s\" uses unsafe RSA signature "
711: "scheme; disabling use of RSA keys", remote_version);
1.59 markus 712: chop(server_version_string);
1.1 deraadt 713: }
714:
1.96 markus 715: /* defaults to 'no' */
1.109 itojun 716: static int
1.112 markus 717: confirm(const char *prompt)
1.1 deraadt 718: {
1.119 markus 719: const char *msg, *again = "Please type 'yes' or 'no': ";
720: char *p;
721: int ret = -1;
1.96 markus 722:
723: if (options.batch_mode)
724: return 0;
1.119 markus 725: for (msg = prompt;;msg = again) {
726: p = read_passphrase(msg, RP_ECHO);
1.289 djm 727: if (p == NULL)
728: return 0;
729: p[strcspn(p, "\n")] = '\0';
730: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 731: ret = 0;
1.289 djm 732: else if (strcasecmp(p, "yes") == 0)
1.119 markus 733: ret = 1;
1.238 djm 734: free(p);
1.119 markus 735: if (ret != -1)
736: return ret;
1.1 deraadt 737: }
738: }
739:
1.219 djm 740: static int
1.279 markus 741: check_host_cert(const char *host, const struct sshkey *host_key)
1.219 djm 742: {
743: const char *reason;
744:
745: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
746: error("%s", reason);
747: return 0;
748: }
1.249 djm 749: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 750: error("Certificate for %s contains unsupported "
751: "critical options(s)", host);
1.219 djm 752: return 0;
753: }
754: return 1;
755: }
756:
1.229 djm 757: static int
758: sockaddr_is_local(struct sockaddr *hostaddr)
759: {
760: switch (hostaddr->sa_family) {
761: case AF_INET:
762: return (ntohl(((struct sockaddr_in *)hostaddr)->
763: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
764: case AF_INET6:
765: return IN6_IS_ADDR_LOOPBACK(
766: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
767: default:
768: return 0;
769: }
770: }
771:
772: /*
773: * Prepare the hostname and ip address strings that are used to lookup
774: * host keys in known_hosts files. These may have a port number appended.
775: */
776: void
777: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
778: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
779: {
780: char ntop[NI_MAXHOST];
781:
782: /*
783: * We don't have the remote ip-address for connections
784: * using a proxy command
785: */
786: if (hostfile_ipaddr != NULL) {
787: if (options.proxy_command == NULL) {
788: if (getnameinfo(hostaddr, hostaddr->sa_len,
789: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 790: fatal("%s: getnameinfo failed", __func__);
1.229 djm 791: *hostfile_ipaddr = put_host_port(ntop, port);
792: } else {
793: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
794: "command>");
795: }
796: }
797:
798: /*
799: * Allow the user to record the key under a different name or
800: * differentiate a non-standard port. This is useful for ssh
801: * tunneling over forwarded connections or if you run multiple
802: * sshd's on different ports on the same machine.
803: */
804: if (hostfile_hostname != NULL) {
805: if (options.host_key_alias != NULL) {
806: *hostfile_hostname = xstrdup(options.host_key_alias);
807: debug("using hostkeyalias: %s", *hostfile_hostname);
808: } else {
809: *hostfile_hostname = put_host_port(hostname, port);
810: }
811: }
812: }
813:
1.39 deraadt 814: /*
1.108 markus 815: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 816: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 817: */
1.197 dtucker 818: #define RDRW 0
819: #define RDONLY 1
820: #define ROQUIET 2
1.109 itojun 821: static int
1.197 dtucker 822: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 823: struct sshkey *host_key, int readonly,
1.234 djm 824: char **user_hostfiles, u_int num_user_hostfiles,
825: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 826: {
1.234 djm 827: HostStatus host_status;
828: HostStatus ip_status;
1.279 markus 829: struct sshkey *raw_key = NULL;
1.189 dtucker 830: char *ip = NULL, *host = NULL;
1.204 grunk 831: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 832: char msg[1024];
1.234 djm 833: const char *type;
834: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 835: int len, cancelled_forwarding = 0;
1.234 djm 836: int local = sockaddr_is_local(hostaddr);
1.280 markus 837: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 838: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 839: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 840: u_int i;
1.49 markus 841:
842: /*
843: * Force accepting of the host key for loopback/localhost. The
844: * problem is that if the home directory is NFS-mounted to multiple
845: * machines, localhost will refer to a different machine in each of
846: * them, and the user will get bogus HOST_CHANGED warnings. This
847: * essentially disables host authentication for localhost; however,
848: * this is probably not a real problem.
849: */
1.111 markus 850: if (options.no_host_authentication_for_localhost == 1 && local &&
851: options.host_key_alias == NULL) {
1.88 markus 852: debug("Forcing accepting of host key for "
853: "loopback/localhost.");
1.108 markus 854: return 0;
1.49 markus 855: }
1.42 markus 856:
857: /*
1.229 djm 858: * Prepare the hostname and address strings used for hostkey lookup.
859: * In some cases, these will have a port number appended.
1.42 markus 860: */
1.229 djm 861: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 862:
863: /*
1.88 markus 864: * Turn off check_host_ip if the connection is to localhost, via proxy
865: * command or if we don't have a hostname to compare with
866: */
1.189 dtucker 867: if (options.check_host_ip && (local ||
868: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 869: options.check_host_ip = 0;
1.86 markus 870:
1.229 djm 871: host_hostkeys = init_hostkeys();
1.234 djm 872: for (i = 0; i < num_user_hostfiles; i++)
873: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
874: for (i = 0; i < num_system_hostfiles; i++)
875: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 876:
877: ip_hostkeys = NULL;
878: if (!want_cert && options.check_host_ip) {
879: ip_hostkeys = init_hostkeys();
1.234 djm 880: for (i = 0; i < num_user_hostfiles; i++)
881: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
882: for (i = 0; i < num_system_hostfiles; i++)
883: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 884: }
1.38 markus 885:
1.219 djm 886: retry:
1.229 djm 887: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 888: want_cert = sshkey_is_cert(host_key);
889: type = sshkey_type(host_key);
1.219 djm 890:
1.46 markus 891: /*
1.170 djm 892: * Check if the host key is present in the user's list of known
1.40 markus 893: * hosts or in the systemwide list.
894: */
1.229 djm 895: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
896: &host_found);
897:
1.40 markus 898: /*
899: * Also perform check for the ip address, skip the check if we are
1.219 djm 900: * localhost, looking for a certificate, or the hostname was an ip
901: * address to begin with.
1.40 markus 902: */
1.229 djm 903: if (!want_cert && ip_hostkeys != NULL) {
904: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
905: &ip_found);
1.38 markus 906: if (host_status == HOST_CHANGED &&
1.229 djm 907: (ip_status != HOST_CHANGED ||
908: (ip_found != NULL &&
1.280 markus 909: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 910: host_ip_differ = 1;
911: } else
912: ip_status = host_status;
913:
914: switch (host_status) {
915: case HOST_OK:
916: /* The host is known and the key matches. */
1.219 djm 917: debug("Host '%.200s' is known and matches the %s host %s.",
918: host, type, want_cert ? "certificate" : "key");
1.229 djm 919: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
920: host_found->file, host_found->line);
1.281 djm 921: if (want_cert &&
922: !check_host_cert(options.host_key_alias == NULL ?
923: hostname : options.host_key_alias, host_key))
1.219 djm 924: goto fail;
1.88 markus 925: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 926: if (readonly || want_cert)
1.138 itojun 927: logit("%s host key for IP address "
1.108 markus 928: "'%.128s' not in list of known hosts.",
929: type, ip);
1.234 djm 930: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 931: host_key, options.hash_known_hosts))
1.138 itojun 932: logit("Failed to add the %s host key for IP "
1.108 markus 933: "address '%.128s' to the list of known "
1.262 dtucker 934: "hosts (%.500s).", type, ip,
1.234 djm 935: user_hostfiles[0]);
1.88 markus 936: else
1.138 itojun 937: logit("Warning: Permanently added the %s host "
1.108 markus 938: "key for IP address '%.128s' to the list "
939: "of known hosts.", type, ip);
1.209 grunk 940: } else if (options.visual_host_key) {
1.259 djm 941: fp = sshkey_fingerprint(host_key,
1.254 djm 942: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 943: ra = sshkey_fingerprint(host_key,
1.254 djm 944: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 945: if (fp == NULL || ra == NULL)
946: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 947: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 948: free(ra);
949: free(fp);
1.38 markus 950: }
1.257 djm 951: hostkey_trusted = 1;
1.38 markus 952: break;
953: case HOST_NEW:
1.197 dtucker 954: if (options.host_key_alias == NULL && port != 0 &&
955: port != SSH_DEFAULT_PORT) {
956: debug("checking without port identifier");
1.212 stevesk 957: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 958: ROQUIET, user_hostfiles, num_user_hostfiles,
959: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 960: debug("found matching key w/out port");
961: break;
962: }
963: }
1.219 djm 964: if (readonly || want_cert)
1.108 markus 965: goto fail;
1.38 markus 966: /* The host is new. */
1.285 djm 967: if (options.strict_host_key_checking ==
968: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 969: /*
970: * User has requested strict host key checking. We
971: * will not add the host key automatically. The only
972: * alternative left is to abort.
973: */
974: error("No %s host key is known for %.200s and you "
975: "have requested strict checking.", type, host);
976: goto fail;
1.285 djm 977: } else if (options.strict_host_key_checking ==
978: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 979: char msg1[1024], msg2[1024];
980:
1.229 djm 981: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 982: snprintf(msg1, sizeof(msg1),
1.168 djm 983: "\nbut keys of different type are already"
984: " known for this host.");
1.145 jakob 985: else
986: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 987: /* The default */
1.259 djm 988: fp = sshkey_fingerprint(host_key,
1.254 djm 989: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 990: ra = sshkey_fingerprint(host_key,
1.254 djm 991: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 992: if (fp == NULL || ra == NULL)
993: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 994: msg2[0] = '\0';
995: if (options.verify_host_key_dns) {
1.153 jakob 996: if (matching_host_key_dns)
1.145 jakob 997: snprintf(msg2, sizeof(msg2),
998: "Matching host key fingerprint"
999: " found in DNS.\n");
1000: else
1001: snprintf(msg2, sizeof(msg2),
1002: "No matching host key fingerprint"
1003: " found in DNS.\n");
1004: }
1.119 markus 1005: snprintf(msg, sizeof(msg),
1.108 markus 1006: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 1007: "established%s\n"
1.209 grunk 1008: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 1009: "Are you sure you want to continue connecting "
1.132 markus 1010: "(yes/no)? ",
1.209 grunk 1011: host, ip, msg1, type, fp,
1012: options.visual_host_key ? "\n" : "",
1013: options.visual_host_key ? ra : "",
1014: msg2);
1.238 djm 1015: free(ra);
1016: free(fp);
1.119 markus 1017: if (!confirm(msg))
1.108 markus 1018: goto fail;
1.257 djm 1019: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 1020: }
1.161 djm 1021: /*
1.285 djm 1022: * If in "new" or "off" strict mode, add the key automatically
1023: * to the local known_hosts file.
1.161 djm 1024: */
1.88 markus 1025: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 1026: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 1027: hostp = hostline;
1.161 djm 1028: if (options.hash_known_hosts) {
1029: /* Add hash of host and IP separately */
1.234 djm 1030: r = add_host_to_hostfile(user_hostfiles[0],
1031: host, host_key, options.hash_known_hosts) &&
1032: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 1033: host_key, options.hash_known_hosts);
1034: } else {
1035: /* Add unhashed "host,ip" */
1.234 djm 1036: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 1037: hostline, host_key,
1038: options.hash_known_hosts);
1039: }
1040: } else {
1.234 djm 1041: r = add_host_to_hostfile(user_hostfiles[0], host,
1042: host_key, options.hash_known_hosts);
1.38 markus 1043: hostp = host;
1.161 djm 1044: }
1.38 markus 1045:
1.161 djm 1046: if (!r)
1.138 itojun 1047: logit("Failed to add the host to the list of known "
1.234 djm 1048: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 1049: else
1.138 itojun 1050: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 1051: "list of known hosts.", hostp, type);
1.38 markus 1052: break;
1.220 djm 1053: case HOST_REVOKED:
1054: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1055: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1056: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1057: error("The %s host key for %s is marked as revoked.", type, host);
1058: error("This could mean that a stolen key is being used to");
1059: error("impersonate this host.");
1060:
1061: /*
1062: * If strict host key checking is in use, the user will have
1063: * to edit the key manually and we can only abort.
1064: */
1.285 djm 1065: if (options.strict_host_key_checking !=
1066: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 1067: error("%s host key for %.200s was revoked and you have "
1068: "requested strict checking.", type, host);
1069: goto fail;
1070: }
1071: goto continue_unsafe;
1072:
1.38 markus 1073: case HOST_CHANGED:
1.219 djm 1074: if (want_cert) {
1075: /*
1076: * This is only a debug() since it is valid to have
1077: * CAs with wildcard DNS matches that don't match
1078: * all hosts that one might visit.
1079: */
1080: debug("Host certificate authority does not "
1.229 djm 1081: "match %s in %s:%lu", CA_MARKER,
1082: host_found->file, host_found->line);
1.219 djm 1083: goto fail;
1084: }
1.197 dtucker 1085: if (readonly == ROQUIET)
1086: goto fail;
1.38 markus 1087: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1088: char *key_msg;
1.38 markus 1089: if (ip_status == HOST_NEW)
1.158 avsm 1090: key_msg = "is unknown";
1.38 markus 1091: else if (ip_status == HOST_OK)
1.158 avsm 1092: key_msg = "is unchanged";
1.38 markus 1093: else
1.158 avsm 1094: key_msg = "has a different value";
1.38 markus 1095: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1096: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1097: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1098: error("The %s host key for %s has changed,", type, host);
1.208 ian 1099: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1100: error("%s. This could either mean that", key_msg);
1.38 markus 1101: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1102: error("and its host key have changed at the same time.");
1.88 markus 1103: if (ip_status != HOST_NEW)
1.229 djm 1104: error("Offending key for IP in %s:%lu",
1105: ip_found->file, ip_found->line);
1.38 markus 1106: }
1107: /* The host key has changed. */
1.150 jakob 1108: warn_changed_key(host_key);
1.38 markus 1109: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1110: user_hostfiles[0]);
1.280 markus 1111: error("Offending %s key in %s:%lu",
1112: sshkey_type(host_found->key),
1.229 djm 1113: host_found->file, host_found->line);
1.38 markus 1114:
1.40 markus 1115: /*
1116: * If strict host key checking is in use, the user will have
1117: * to edit the key manually and we can only abort.
1118: */
1.285 djm 1119: if (options.strict_host_key_checking !=
1120: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 1121: error("%s host key for %.200s has changed and you have "
1122: "requested strict checking.", type, host);
1123: goto fail;
1124: }
1.38 markus 1125:
1.220 djm 1126: continue_unsafe:
1.40 markus 1127: /*
1128: * If strict host key checking has not been requested, allow
1.144 djm 1129: * the connection but without MITM-able authentication or
1.194 stevesk 1130: * forwarding.
1.40 markus 1131: */
1.38 markus 1132: if (options.password_authentication) {
1.108 markus 1133: error("Password authentication is disabled to avoid "
1134: "man-in-the-middle attacks.");
1.38 markus 1135: options.password_authentication = 0;
1.210 dtucker 1136: cancelled_forwarding = 1;
1.144 djm 1137: }
1138: if (options.kbd_interactive_authentication) {
1139: error("Keyboard-interactive authentication is disabled"
1140: " to avoid man-in-the-middle attacks.");
1141: options.kbd_interactive_authentication = 0;
1142: options.challenge_response_authentication = 0;
1.210 dtucker 1143: cancelled_forwarding = 1;
1.144 djm 1144: }
1145: if (options.challenge_response_authentication) {
1146: error("Challenge/response authentication is disabled"
1147: " to avoid man-in-the-middle attacks.");
1148: options.challenge_response_authentication = 0;
1.210 dtucker 1149: cancelled_forwarding = 1;
1.38 markus 1150: }
1151: if (options.forward_agent) {
1.108 markus 1152: error("Agent forwarding is disabled to avoid "
1153: "man-in-the-middle attacks.");
1.38 markus 1154: options.forward_agent = 0;
1.210 dtucker 1155: cancelled_forwarding = 1;
1.83 markus 1156: }
1157: if (options.forward_x11) {
1.108 markus 1158: error("X11 forwarding is disabled to avoid "
1159: "man-in-the-middle attacks.");
1.83 markus 1160: options.forward_x11 = 0;
1.210 dtucker 1161: cancelled_forwarding = 1;
1.83 markus 1162: }
1.108 markus 1163: if (options.num_local_forwards > 0 ||
1164: options.num_remote_forwards > 0) {
1165: error("Port forwarding is disabled to avoid "
1166: "man-in-the-middle attacks.");
1167: options.num_local_forwards =
1.118 deraadt 1168: options.num_remote_forwards = 0;
1.210 dtucker 1169: cancelled_forwarding = 1;
1.194 stevesk 1170: }
1171: if (options.tun_open != SSH_TUNMODE_NO) {
1172: error("Tunnel forwarding is disabled to avoid "
1173: "man-in-the-middle attacks.");
1174: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1175: cancelled_forwarding = 1;
1.38 markus 1176: }
1.210 dtucker 1177: if (options.exit_on_forward_failure && cancelled_forwarding)
1178: fatal("Error: forwarding disabled due to host key "
1179: "check failure");
1180:
1.40 markus 1181: /*
1182: * XXX Should permit the user to change to use the new id.
1183: * This could be done by converting the host key to an
1184: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1185: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1186: * accept the authentication.
1187: */
1.38 markus 1188: break;
1.132 markus 1189: case HOST_FOUND:
1190: fatal("internal error");
1191: break;
1.88 markus 1192: }
1193:
1194: if (options.check_host_ip && host_status != HOST_CHANGED &&
1195: ip_status == HOST_CHANGED) {
1.119 markus 1196: snprintf(msg, sizeof(msg),
1197: "Warning: the %s host key for '%.200s' "
1198: "differs from the key for the IP address '%.128s'"
1.229 djm 1199: "\nOffending key for IP in %s:%lu",
1200: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1201: if (host_status == HOST_OK) {
1202: len = strlen(msg);
1203: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1204: "\nMatching host key in %s:%lu",
1205: host_found->file, host_found->line);
1.119 markus 1206: }
1.285 djm 1207: if (options.strict_host_key_checking ==
1208: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1209: strlcat(msg, "\nAre you sure you want "
1210: "to continue connecting (yes/no)? ", sizeof(msg));
1211: if (!confirm(msg))
1.108 markus 1212: goto fail;
1.285 djm 1213: } else if (options.strict_host_key_checking !=
1214: SSH_STRICT_HOSTKEY_OFF) {
1215: logit("%s", msg);
1216: error("Exiting, you have requested strict checking.");
1217: goto fail;
1.119 markus 1218: } else {
1.143 djm 1219: logit("%s", msg);
1.88 markus 1220: }
1.257 djm 1221: }
1222:
1223: if (!hostkey_trusted && options.update_hostkeys) {
1224: debug("%s: hostkey not known or explicitly trusted: "
1225: "disabling UpdateHostkeys", __func__);
1226: options.update_hostkeys = 0;
1.38 markus 1227: }
1.82 provos 1228:
1.238 djm 1229: free(ip);
1230: free(host);
1.229 djm 1231: if (host_hostkeys != NULL)
1232: free_hostkeys(host_hostkeys);
1233: if (ip_hostkeys != NULL)
1234: free_hostkeys(ip_hostkeys);
1.108 markus 1235: return 0;
1236:
1237: fail:
1.220 djm 1238: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1239: /*
1240: * No matching certificate. Downgrade cert to raw key and
1241: * search normally.
1242: */
1243: debug("No matching CA found. Retry with plain key");
1.280 markus 1244: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1245: fatal("%s: sshkey_from_private: %s",
1246: __func__, ssh_err(r));
1247: if ((r = sshkey_drop_cert(raw_key)) != 0)
1248: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1249: host_key = raw_key;
1250: goto retry;
1251: }
1.293 dtucker 1252: sshkey_free(raw_key);
1.238 djm 1253: free(ip);
1254: free(host);
1.229 djm 1255: if (host_hostkeys != NULL)
1256: free_hostkeys(host_hostkeys);
1257: if (ip_hostkeys != NULL)
1258: free_hostkeys(ip_hostkeys);
1.108 markus 1259: return -1;
1260: }
1261:
1.140 jakob 1262: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1263: int
1.279 markus 1264: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1265: {
1.267 djm 1266: u_int i;
1.250 djm 1267: int r = -1, flags = 0;
1.267 djm 1268: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1269: struct sshkey *plain = NULL;
1.229 djm 1270:
1.252 djm 1271: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1272: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1273: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1274: r = -1;
1275: goto out;
1276: }
1277:
1.267 djm 1278: if (sshkey_is_cert(host_key)) {
1279: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1280: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1281: error("%s: fingerprint CA key: %s",
1282: __func__, ssh_err(r));
1283: r = -1;
1284: goto out;
1285: }
1286: sshkey_format_cert_validity(host_key->cert,
1287: valid, sizeof(valid));
1288: debug("Server host certificate: %s %s, serial %llu "
1289: "ID \"%s\" CA %s %s valid %s",
1290: sshkey_ssh_name(host_key), fp,
1.269 djm 1291: (unsigned long long)host_key->cert->serial,
1292: host_key->cert->key_id,
1.267 djm 1293: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1294: valid);
1295: for (i = 0; i < host_key->cert->nprincipals; i++) {
1296: debug2("Server host certificate hostname: %s",
1297: host_key->cert->principals[i]);
1298: }
1299: } else {
1.276 djm 1300: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1301: }
1.252 djm 1302:
1303: if (sshkey_equal(previous_host_key, host_key)) {
1304: debug2("%s: server host key %s %s matches cached key",
1305: __func__, sshkey_type(host_key), fp);
1306: r = 0;
1307: goto out;
1308: }
1309:
1310: /* Check in RevokedHostKeys file if specified */
1311: if (options.revoked_host_keys != NULL) {
1312: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1313: switch (r) {
1314: case 0:
1315: break; /* not revoked */
1316: case SSH_ERR_KEY_REVOKED:
1317: error("Host key %s %s revoked by file %s",
1318: sshkey_type(host_key), fp,
1319: options.revoked_host_keys);
1320: r = -1;
1321: goto out;
1322: default:
1323: error("Error checking host key %s %s in "
1324: "revoked keys file %s: %s", sshkey_type(host_key),
1325: fp, options.revoked_host_keys, ssh_err(r));
1326: r = -1;
1327: goto out;
1328: }
1.250 djm 1329: }
1330:
1.247 djm 1331: if (options.verify_host_key_dns) {
1332: /*
1333: * XXX certs are not yet supported for DNS, so downgrade
1334: * them and try the plain key.
1335: */
1.252 djm 1336: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1337: goto out;
1338: if (sshkey_is_cert(plain))
1339: sshkey_drop_cert(plain);
1.247 djm 1340: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1341: if (flags & DNS_VERIFY_FOUND) {
1342: if (options.verify_host_key_dns == 1 &&
1343: flags & DNS_VERIFY_MATCH &&
1344: flags & DNS_VERIFY_SECURE) {
1.250 djm 1345: r = 0;
1.252 djm 1346: goto out;
1.247 djm 1347: }
1348: if (flags & DNS_VERIFY_MATCH) {
1349: matching_host_key_dns = 1;
1350: } else {
1.287 djm 1351: warn_changed_key(plain);
1352: error("Update the SSHFP RR in DNS "
1353: "with the new host key to get rid "
1354: "of this message.");
1.247 djm 1355: }
1.153 jakob 1356: }
1.140 jakob 1357: }
1358: }
1.250 djm 1359: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1360: options.user_hostfiles, options.num_user_hostfiles,
1361: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1362:
1.252 djm 1363: out:
1364: sshkey_free(plain);
1365: free(fp);
1.267 djm 1366: free(cafp);
1.250 djm 1367: if (r == 0 && host_key != NULL) {
1.280 markus 1368: sshkey_free(previous_host_key);
1369: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1370: }
1371:
1372: return r;
1.51 markus 1373: }
1.70 markus 1374:
1.51 markus 1375: /*
1376: * Starts a dialog with the server, and authenticates the current user on the
1377: * server. This does not need any extra privileges. The basic connection
1378: * to the server must already have been established before this is called.
1379: * If login fails, this function prints an error and never returns.
1380: * This function does not require super-user privileges.
1381: */
1382: void
1.120 markus 1383: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1384: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1385: {
1.241 djm 1386: char *host;
1.70 markus 1387: char *server_user, *local_user;
1388:
1389: local_user = xstrdup(pw->pw_name);
1390: server_user = options.user ? options.user : local_user;
1.51 markus 1391:
1392: /* Convert the user-supplied hostname into all lowercase. */
1393: host = xstrdup(orighost);
1.241 djm 1394: lowercase(host);
1.51 markus 1395:
1396: /* Exchange protocol version identification strings with the server. */
1.202 djm 1397: ssh_exchange_identification(timeout_ms);
1.51 markus 1398:
1399: /* Put the connection into non-blocking mode. */
1400: packet_set_nonblocking();
1401:
1402: /* key exchange */
1403: /* authenticate user */
1.261 dtucker 1404: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.276 djm 1405: ssh_kex2(host, hostaddr, port);
1406: ssh_userauth2(local_user, server_user, host, sensitive);
1.238 djm 1407: free(local_user);
1.97 markus 1408: }
1409:
1410: void
1411: ssh_put_password(char *password)
1412: {
1413: int size;
1414: char *padded;
1415:
1.99 deraadt 1416: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1417: packet_put_cstring(password);
1.99 deraadt 1418: return;
1419: }
1.272 deraadt 1420: size = ROUNDUP(strlen(password) + 1, 32);
1.179 djm 1421: padded = xcalloc(1, size);
1.97 markus 1422: strlcpy(padded, password, size);
1423: packet_put_string(padded, size);
1.245 djm 1424: explicit_bzero(padded, size);
1.238 djm 1425: free(padded);
1.132 markus 1426: }
1427:
1428: /* print all known host keys for a given host, but skip keys of given type */
1429: static int
1.279 markus 1430: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1431: {
1.242 djm 1432: int type[] = {
1433: KEY_RSA,
1434: KEY_DSA,
1435: KEY_ECDSA,
1436: KEY_ED25519,
1437: -1
1438: };
1.229 djm 1439: int i, ret = 0;
1440: char *fp, *ra;
1441: const struct hostkey_entry *found;
1.132 markus 1442:
1443: for (i = 0; type[i] != -1; i++) {
1444: if (type[i] == key->type)
1445: continue;
1.229 djm 1446: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1447: continue;
1.259 djm 1448: fp = sshkey_fingerprint(found->key,
1.254 djm 1449: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1450: ra = sshkey_fingerprint(found->key,
1.254 djm 1451: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1452: if (fp == NULL || ra == NULL)
1453: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1454: logit("WARNING: %s key found for host %s\n"
1455: "in %s:%lu\n"
1456: "%s key fingerprint %s.",
1457: key_type(found->key),
1458: found->host, found->file, found->line,
1459: key_type(found->key), fp);
1460: if (options.visual_host_key)
1461: logit("%s", ra);
1.238 djm 1462: free(ra);
1463: free(fp);
1.229 djm 1464: ret = 1;
1.132 markus 1465: }
1.229 djm 1466: return ret;
1.150 jakob 1467: }
1468:
1469: static void
1.279 markus 1470: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1471: {
1472: char *fp;
1473:
1.259 djm 1474: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1475: SSH_FP_DEFAULT);
1.259 djm 1476: if (fp == NULL)
1477: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1478:
1479: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1480: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1481: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1482: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1483: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1484: error("It is also possible that a host key has just been changed.");
1.150 jakob 1485: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.287 djm 1486: key_type(host_key), fp);
1.150 jakob 1487: error("Please contact your system administrator.");
1488:
1.238 djm 1489: free(fp);
1.171 reyk 1490: }
1491:
1492: /*
1493: * Execute a local command
1494: */
1495: int
1496: ssh_local_cmd(const char *args)
1497: {
1498: char *shell;
1499: pid_t pid;
1500: int status;
1.231 djm 1501: void (*osighand)(int);
1.171 reyk 1502:
1503: if (!options.permit_local_command ||
1504: args == NULL || !*args)
1505: return (1);
1506:
1.226 djm 1507: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1508: shell = _PATH_BSHELL;
1509:
1.231 djm 1510: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1511: pid = fork();
1512: if (pid == 0) {
1.232 djm 1513: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1514: debug3("Executing %s -c \"%s\"", shell, args);
1515: execl(shell, shell, "-c", args, (char *)NULL);
1516: error("Couldn't execute %s -c \"%s\": %s",
1517: shell, args, strerror(errno));
1518: _exit(1);
1519: } else if (pid == -1)
1520: fatal("fork failed: %.100s", strerror(errno));
1521: while (waitpid(pid, &status, 0) == -1)
1522: if (errno != EINTR)
1523: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1524: signal(SIGCHLD, osighand);
1.171 reyk 1525:
1526: if (!WIFEXITED(status))
1527: return (1);
1528:
1529: return (WEXITSTATUS(status));
1.266 jcs 1530: }
1531:
1532: void
1.294 djm 1533: maybe_add_key_to_agent(char *authfile, const struct sshkey *private,
1534: char *comment, char *passphrase)
1.266 jcs 1535: {
1536: int auth_sock = -1, r;
1537:
1538: if (options.add_keys_to_agent == 0)
1539: return;
1540:
1541: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1542: debug3("no authentication agent, not adding key");
1543: return;
1544: }
1545:
1546: if (options.add_keys_to_agent == 2 &&
1547: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1548: debug3("user denied adding this key");
1.273 dtucker 1549: close(auth_sock);
1.266 jcs 1550: return;
1551: }
1552:
1553: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1554: (options.add_keys_to_agent == 3))) == 0)
1555: debug("identity added to agent: %s", authfile);
1556: else
1557: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1558: close(auth_sock);
1.1 deraadt 1559: }
![[BACK]](/icons/back.gif){kind=icon}
Return to sshconnect.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh