Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.299
1.299 ! markus 1: /* $OpenBSD: sshconnect.c,v 1.298 2018/04/10 00:10:49 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"
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
1.298 djm 265: * address that matches the desired address family on the specified interface.
1.295 djm 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: }
1.296 dtucker 361: if (res == NULL) {
1.295 djm 362: error("getaddrinfo: no addrs");
363: goto fail;
1.296 dtucker 364: }
1.295 djm 365: if (res->ai_addrlen > sizeof(bindaddr)) {
366: error("%s: addr doesn't fit", __func__);
367: goto fail;
368: }
369: memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
370: bindaddrlen = res->ai_addrlen;
371: } else if (options.bind_interface != NULL) {
372: if ((r = getifaddrs(&ifaddrs)) != 0) {
373: error("getifaddrs: %s: %s", options.bind_interface,
374: strerror(errno));
375: goto fail;
376: }
377: bindaddrlen = sizeof(bindaddr);
378: if (check_ifaddrs(options.bind_interface, ai->ai_family,
379: ifaddrs, &bindaddr, &bindaddrlen) != 0) {
380: logit("getifaddrs: %s: no suitable addresses",
381: options.bind_interface);
382: goto fail;
1.246 djm 383: }
1.105 markus 384: }
1.295 djm 385: if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
386: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
387: error("%s: getnameinfo failed: %s", __func__,
388: ssh_gai_strerror(r));
389: goto fail;
390: }
1.240 djm 391: /*
392: * If we are running as root and want to connect to a privileged
393: * port, bind our own socket to a privileged port.
394: */
395: if (privileged) {
396: PRIV_START;
1.295 djm 397: r = bindresvport_sa(sock,
398: bindaddrlen == 0 ? NULL : (struct sockaddr *)&bindaddr);
399: oerrno = errno;
1.240 djm 400: PRIV_END;
401: if (r < 0) {
1.295 djm 402: error("bindresvport_sa %s: %s", ntop,
403: strerror(oerrno));
1.240 djm 404: goto fail;
405: }
1.295 djm 406: } else if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
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.
1.124 markus 494: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 495: * a privileged port will be allocated to make the connection.
1.124 markus 496: * This requires super-user privileges if needpriv is true.
1.39 deraadt 497: * Connection_attempts specifies the maximum number of tries (one per
498: * second). If proxy_command is non-NULL, it specifies the command (with %h
499: * and %p substituted for host and port, respectively) to use to contact
500: * the daemon.
501: */
1.241 djm 502: static int
1.286 djm 503: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.241 djm 504: struct sockaddr_storage *hostaddr, u_short port, int family,
505: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
1.1 deraadt 506: {
1.90 markus 507: int on = 1;
1.290 djm 508: int oerrno, sock = -1, attempt;
1.90 markus 509: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 510: struct addrinfo *ai;
1.38 markus 511:
1.265 djm 512: debug2("%s: needpriv %d", __func__, needpriv);
1.268 djm 513: memset(ntop, 0, sizeof(ntop));
514: memset(strport, 0, sizeof(strport));
1.38 markus 515:
1.181 markus 516: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 517: if (attempt > 0) {
518: /* Sleep a moment before retrying. */
519: sleep(1);
1.38 markus 520: debug("Trying again...");
1.200 markus 521: }
1.181 markus 522: /*
523: * Loop through addresses for this host, and try each one in
524: * sequence until the connection succeeds.
525: */
1.49 markus 526: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 527: if (ai->ai_family != AF_INET &&
1.290 djm 528: ai->ai_family != AF_INET6) {
529: errno = EAFNOSUPPORT;
1.49 markus 530: continue;
1.290 djm 531: }
1.49 markus 532: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
533: ntop, sizeof(ntop), strport, sizeof(strport),
534: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.290 djm 535: oerrno = errno;
1.265 djm 536: error("%s: getnameinfo failed", __func__);
1.290 djm 537: errno = oerrno;
1.49 markus 538: continue;
539: }
540: debug("Connecting to %.200s [%.100s] port %s.",
541: host, ntop, strport);
542:
543: /* Create a socket for connecting. */
1.139 markus 544: sock = ssh_create_socket(needpriv, ai);
1.292 stsp 545: if (sock < 0) {
1.110 markus 546: /* Any error is already output */
1.290 djm 547: errno = 0;
1.49 markus 548: continue;
1.292 stsp 549: }
1.49 markus 550:
1.141 djm 551: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 552: timeout_ms) >= 0) {
1.49 markus 553: /* Successful connection. */
1.102 markus 554: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 555: break;
1.49 markus 556: } else {
1.290 djm 557: oerrno = errno;
1.131 itojun 558: debug("connect to address %s port %s: %s",
559: ntop, strport, strerror(errno));
1.38 markus 560: close(sock);
1.181 markus 561: sock = -1;
1.290 djm 562: errno = oerrno;
1.38 markus 563: }
564: }
1.181 markus 565: if (sock != -1)
1.49 markus 566: break; /* Successful connection. */
1.38 markus 567: }
1.49 markus 568:
1.38 markus 569: /* Return failure if we didn't get a successful connection. */
1.181 markus 570: if (sock == -1) {
1.159 markus 571: error("ssh: connect to host %s port %s: %s",
1.290 djm 572: host, strport, errno == 0 ? "failure" : strerror(errno));
573: return -1;
1.130 itojun 574: }
1.38 markus 575:
576: debug("Connection established.");
1.90 markus 577:
1.155 markus 578: /* Set SO_KEEPALIVE if requested. */
1.202 djm 579: if (want_keepalive &&
1.90 markus 580: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
581: sizeof(on)) < 0)
582: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 583:
584: /* Set the connection. */
1.286 djm 585: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
586: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 587:
1.286 djm 588: return 0;
1.59 markus 589: }
590:
1.241 djm 591: int
1.286 djm 592: ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs,
1.241 djm 593: struct sockaddr_storage *hostaddr, u_short port, int family,
594: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
595: {
596: if (options.proxy_command == NULL) {
1.286 djm 597: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
598: family, connection_attempts, timeout_ms, want_keepalive,
599: needpriv);
1.241 djm 600: } else if (strcmp(options.proxy_command, "-") == 0) {
1.286 djm 601: if ((ssh_packet_set_connection(ssh,
602: STDIN_FILENO, STDOUT_FILENO)) == NULL)
603: return -1; /* ssh_packet_set_connection logs error */
604: return 0;
1.241 djm 605: } else if (options.proxy_use_fdpass) {
1.286 djm 606: return ssh_proxy_fdpass_connect(ssh, host, port,
1.241 djm 607: options.proxy_command);
608: }
1.286 djm 609: return ssh_proxy_connect(ssh, host, port, options.proxy_command);
1.241 djm 610: }
611:
1.235 djm 612: static void
613: send_client_banner(int connection_out, int minor1)
614: {
615: /* Send our own protocol version identification. */
1.276 djm 616: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
617: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
1.270 markus 618: if (atomicio(vwrite, connection_out, client_version_string,
1.235 djm 619: strlen(client_version_string)) != strlen(client_version_string))
620: fatal("write: %.100s", strerror(errno));
621: chop(client_version_string);
622: debug("Local version string %.100s", client_version_string);
623: }
624:
1.43 markus 625: /*
1.39 deraadt 626: * Waits for the server identification string, and sends our own
627: * identification string.
628: */
1.213 andreas 629: void
1.202 djm 630: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 631: {
1.38 markus 632: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 633: int remote_major, remote_minor, mismatch;
1.38 markus 634: int connection_in = packet_get_connection_in();
635: int connection_out = packet_get_connection_out();
1.185 djm 636: u_int i, n;
1.202 djm 637: size_t len;
1.282 djm 638: int rc;
1.38 markus 639:
1.275 djm 640: send_client_banner(connection_out, 0);
1.235 djm 641:
1.163 avsm 642: /* Read other side's version identification. */
1.185 djm 643: for (n = 0;;) {
1.75 markus 644: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 645: if (timeout_ms > 0) {
1.282 djm 646: rc = waitrfd(connection_in, &timeout_ms);
647: if (rc == -1 && errno == ETIMEDOUT) {
1.202 djm 648: fatal("Connection timed out during "
649: "banner exchange");
1.282 djm 650: } else if (rc == -1) {
651: fatal("%s: %s",
652: __func__, strerror(errno));
1.202 djm 653: }
654: }
655:
1.270 markus 656: len = atomicio(read, connection_in, &buf[i], 1);
1.167 djm 657: if (len != 1 && errno == EPIPE)
1.202 djm 658: fatal("ssh_exchange_identification: "
659: "Connection closed by remote host");
1.163 avsm 660: else if (len != 1)
1.202 djm 661: fatal("ssh_exchange_identification: "
662: "read: %.100s", strerror(errno));
1.75 markus 663: if (buf[i] == '\r') {
664: buf[i] = '\n';
665: buf[i + 1] = 0;
666: continue; /**XXX wait for \n */
667: }
668: if (buf[i] == '\n') {
669: buf[i + 1] = 0;
670: break;
671: }
1.185 djm 672: if (++n > 65536)
1.202 djm 673: fatal("ssh_exchange_identification: "
674: "No banner received");
1.38 markus 675: }
1.75 markus 676: buf[sizeof(buf) - 1] = 0;
1.76 markus 677: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 678: break;
1.75 markus 679: debug("ssh_exchange_identification: %s", buf);
1.38 markus 680: }
1.59 markus 681: server_version_string = xstrdup(buf);
1.38 markus 682:
1.40 markus 683: /*
684: * Check that the versions match. In future this might accept
685: * several versions and set appropriate flags to handle them.
686: */
1.59 markus 687: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
688: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 689: fatal("Bad remote protocol version identification: '%.100s'", buf);
690: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 691: remote_major, remote_minor, remote_version);
1.38 markus 692:
1.255 markus 693: active_state->compat = compat_datafellows(remote_version);
1.64 markus 694: mismatch = 0;
1.59 markus 695:
1.116 deraadt 696: switch (remote_major) {
1.276 djm 697: case 2:
698: break;
1.64 markus 699: case 1:
1.276 djm 700: if (remote_minor != 99)
1.64 markus 701: mismatch = 1;
702: break;
1.68 markus 703: default:
1.64 markus 704: mismatch = 1;
705: break;
1.38 markus 706: }
1.64 markus 707: if (mismatch)
1.38 markus 708: fatal("Protocol major versions differ: %d vs. %d",
1.275 djm 709: PROTOCOL_MAJOR_2, remote_major);
1.243 djm 710: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
711: logit("Server version \"%.100s\" uses unsafe RSA signature "
712: "scheme; disabling use of RSA keys", remote_version);
1.59 markus 713: chop(server_version_string);
1.1 deraadt 714: }
715:
1.96 markus 716: /* defaults to 'no' */
1.109 itojun 717: static int
1.112 markus 718: confirm(const char *prompt)
1.1 deraadt 719: {
1.119 markus 720: const char *msg, *again = "Please type 'yes' or 'no': ";
721: char *p;
722: int ret = -1;
1.96 markus 723:
724: if (options.batch_mode)
725: return 0;
1.119 markus 726: for (msg = prompt;;msg = again) {
727: p = read_passphrase(msg, RP_ECHO);
1.289 djm 728: if (p == NULL)
729: return 0;
730: p[strcspn(p, "\n")] = '\0';
731: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 732: ret = 0;
1.289 djm 733: else if (strcasecmp(p, "yes") == 0)
1.119 markus 734: ret = 1;
1.238 djm 735: free(p);
1.119 markus 736: if (ret != -1)
737: return ret;
1.1 deraadt 738: }
739: }
740:
1.219 djm 741: static int
1.279 markus 742: check_host_cert(const char *host, const struct sshkey *host_key)
1.219 djm 743: {
744: const char *reason;
745:
746: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
747: error("%s", reason);
748: return 0;
749: }
1.299 ! markus 750: if (sshbuf_len(host_key->cert->critical) != 0) {
1.223 djm 751: error("Certificate for %s contains unsupported "
752: "critical options(s)", host);
1.219 djm 753: return 0;
754: }
755: return 1;
756: }
757:
1.229 djm 758: static int
759: sockaddr_is_local(struct sockaddr *hostaddr)
760: {
761: switch (hostaddr->sa_family) {
762: case AF_INET:
763: return (ntohl(((struct sockaddr_in *)hostaddr)->
764: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
765: case AF_INET6:
766: return IN6_IS_ADDR_LOOPBACK(
767: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
768: default:
769: return 0;
770: }
771: }
772:
773: /*
774: * Prepare the hostname and ip address strings that are used to lookup
775: * host keys in known_hosts files. These may have a port number appended.
776: */
777: void
778: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
779: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
780: {
781: char ntop[NI_MAXHOST];
782:
783: /*
784: * We don't have the remote ip-address for connections
785: * using a proxy command
786: */
787: if (hostfile_ipaddr != NULL) {
788: if (options.proxy_command == NULL) {
789: if (getnameinfo(hostaddr, hostaddr->sa_len,
790: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 791: fatal("%s: getnameinfo failed", __func__);
1.229 djm 792: *hostfile_ipaddr = put_host_port(ntop, port);
793: } else {
794: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
795: "command>");
796: }
797: }
798:
799: /*
800: * Allow the user to record the key under a different name or
801: * differentiate a non-standard port. This is useful for ssh
802: * tunneling over forwarded connections or if you run multiple
803: * sshd's on different ports on the same machine.
804: */
805: if (hostfile_hostname != NULL) {
806: if (options.host_key_alias != NULL) {
807: *hostfile_hostname = xstrdup(options.host_key_alias);
808: debug("using hostkeyalias: %s", *hostfile_hostname);
809: } else {
810: *hostfile_hostname = put_host_port(hostname, port);
811: }
812: }
813: }
814:
1.39 deraadt 815: /*
1.108 markus 816: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 817: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 818: */
1.197 dtucker 819: #define RDRW 0
820: #define RDONLY 1
821: #define ROQUIET 2
1.109 itojun 822: static int
1.197 dtucker 823: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 824: struct sshkey *host_key, int readonly,
1.234 djm 825: char **user_hostfiles, u_int num_user_hostfiles,
826: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 827: {
1.234 djm 828: HostStatus host_status;
829: HostStatus ip_status;
1.279 markus 830: struct sshkey *raw_key = NULL;
1.189 dtucker 831: char *ip = NULL, *host = NULL;
1.204 grunk 832: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 833: char msg[1024];
1.234 djm 834: const char *type;
835: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 836: int len, cancelled_forwarding = 0;
1.234 djm 837: int local = sockaddr_is_local(hostaddr);
1.280 markus 838: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 839: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 840: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 841: u_int i;
1.49 markus 842:
843: /*
844: * Force accepting of the host key for loopback/localhost. The
845: * problem is that if the home directory is NFS-mounted to multiple
846: * machines, localhost will refer to a different machine in each of
847: * them, and the user will get bogus HOST_CHANGED warnings. This
848: * essentially disables host authentication for localhost; however,
849: * this is probably not a real problem.
850: */
1.111 markus 851: if (options.no_host_authentication_for_localhost == 1 && local &&
852: options.host_key_alias == NULL) {
1.88 markus 853: debug("Forcing accepting of host key for "
854: "loopback/localhost.");
1.108 markus 855: return 0;
1.49 markus 856: }
1.42 markus 857:
858: /*
1.229 djm 859: * Prepare the hostname and address strings used for hostkey lookup.
860: * In some cases, these will have a port number appended.
1.42 markus 861: */
1.229 djm 862: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 863:
864: /*
1.88 markus 865: * Turn off check_host_ip if the connection is to localhost, via proxy
866: * command or if we don't have a hostname to compare with
867: */
1.189 dtucker 868: if (options.check_host_ip && (local ||
869: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 870: options.check_host_ip = 0;
1.86 markus 871:
1.229 djm 872: host_hostkeys = init_hostkeys();
1.234 djm 873: for (i = 0; i < num_user_hostfiles; i++)
874: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
875: for (i = 0; i < num_system_hostfiles; i++)
876: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 877:
878: ip_hostkeys = NULL;
879: if (!want_cert && options.check_host_ip) {
880: ip_hostkeys = init_hostkeys();
1.234 djm 881: for (i = 0; i < num_user_hostfiles; i++)
882: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
883: for (i = 0; i < num_system_hostfiles; i++)
884: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 885: }
1.38 markus 886:
1.219 djm 887: retry:
1.229 djm 888: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 889: want_cert = sshkey_is_cert(host_key);
890: type = sshkey_type(host_key);
1.219 djm 891:
1.46 markus 892: /*
1.170 djm 893: * Check if the host key is present in the user's list of known
1.40 markus 894: * hosts or in the systemwide list.
895: */
1.229 djm 896: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
897: &host_found);
898:
1.40 markus 899: /*
900: * Also perform check for the ip address, skip the check if we are
1.219 djm 901: * localhost, looking for a certificate, or the hostname was an ip
902: * address to begin with.
1.40 markus 903: */
1.229 djm 904: if (!want_cert && ip_hostkeys != NULL) {
905: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
906: &ip_found);
1.38 markus 907: if (host_status == HOST_CHANGED &&
1.229 djm 908: (ip_status != HOST_CHANGED ||
909: (ip_found != NULL &&
1.280 markus 910: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 911: host_ip_differ = 1;
912: } else
913: ip_status = host_status;
914:
915: switch (host_status) {
916: case HOST_OK:
917: /* The host is known and the key matches. */
1.219 djm 918: debug("Host '%.200s' is known and matches the %s host %s.",
919: host, type, want_cert ? "certificate" : "key");
1.229 djm 920: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
921: host_found->file, host_found->line);
1.281 djm 922: if (want_cert &&
923: !check_host_cert(options.host_key_alias == NULL ?
924: hostname : options.host_key_alias, host_key))
1.219 djm 925: goto fail;
1.88 markus 926: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 927: if (readonly || want_cert)
1.138 itojun 928: logit("%s host key for IP address "
1.108 markus 929: "'%.128s' not in list of known hosts.",
930: type, ip);
1.234 djm 931: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 932: host_key, options.hash_known_hosts))
1.138 itojun 933: logit("Failed to add the %s host key for IP "
1.108 markus 934: "address '%.128s' to the list of known "
1.262 dtucker 935: "hosts (%.500s).", type, ip,
1.234 djm 936: user_hostfiles[0]);
1.88 markus 937: else
1.138 itojun 938: logit("Warning: Permanently added the %s host "
1.108 markus 939: "key for IP address '%.128s' to the list "
940: "of known hosts.", type, ip);
1.209 grunk 941: } else if (options.visual_host_key) {
1.259 djm 942: fp = sshkey_fingerprint(host_key,
1.254 djm 943: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 944: ra = sshkey_fingerprint(host_key,
1.254 djm 945: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 946: if (fp == NULL || ra == NULL)
947: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 948: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 949: free(ra);
950: free(fp);
1.38 markus 951: }
1.257 djm 952: hostkey_trusted = 1;
1.38 markus 953: break;
954: case HOST_NEW:
1.197 dtucker 955: if (options.host_key_alias == NULL && port != 0 &&
956: port != SSH_DEFAULT_PORT) {
957: debug("checking without port identifier");
1.212 stevesk 958: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 959: ROQUIET, user_hostfiles, num_user_hostfiles,
960: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 961: debug("found matching key w/out port");
962: break;
963: }
964: }
1.219 djm 965: if (readonly || want_cert)
1.108 markus 966: goto fail;
1.38 markus 967: /* The host is new. */
1.285 djm 968: if (options.strict_host_key_checking ==
969: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 970: /*
971: * User has requested strict host key checking. We
972: * will not add the host key automatically. The only
973: * alternative left is to abort.
974: */
975: error("No %s host key is known for %.200s and you "
976: "have requested strict checking.", type, host);
977: goto fail;
1.285 djm 978: } else if (options.strict_host_key_checking ==
979: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 980: char msg1[1024], msg2[1024];
981:
1.229 djm 982: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 983: snprintf(msg1, sizeof(msg1),
1.168 djm 984: "\nbut keys of different type are already"
985: " known for this host.");
1.145 jakob 986: else
987: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 988: /* The default */
1.259 djm 989: fp = sshkey_fingerprint(host_key,
1.254 djm 990: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 991: ra = sshkey_fingerprint(host_key,
1.254 djm 992: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 993: if (fp == NULL || ra == NULL)
994: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 995: msg2[0] = '\0';
996: if (options.verify_host_key_dns) {
1.153 jakob 997: if (matching_host_key_dns)
1.145 jakob 998: snprintf(msg2, sizeof(msg2),
999: "Matching host key fingerprint"
1000: " found in DNS.\n");
1001: else
1002: snprintf(msg2, sizeof(msg2),
1003: "No matching host key fingerprint"
1004: " found in DNS.\n");
1005: }
1.119 markus 1006: snprintf(msg, sizeof(msg),
1.108 markus 1007: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 1008: "established%s\n"
1.209 grunk 1009: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 1010: "Are you sure you want to continue connecting "
1.132 markus 1011: "(yes/no)? ",
1.209 grunk 1012: host, ip, msg1, type, fp,
1013: options.visual_host_key ? "\n" : "",
1014: options.visual_host_key ? ra : "",
1015: msg2);
1.238 djm 1016: free(ra);
1017: free(fp);
1.119 markus 1018: if (!confirm(msg))
1.108 markus 1019: goto fail;
1.257 djm 1020: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 1021: }
1.161 djm 1022: /*
1.285 djm 1023: * If in "new" or "off" strict mode, add the key automatically
1024: * to the local known_hosts file.
1.161 djm 1025: */
1.88 markus 1026: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 1027: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 1028: hostp = hostline;
1.161 djm 1029: if (options.hash_known_hosts) {
1030: /* Add hash of host and IP separately */
1.234 djm 1031: r = add_host_to_hostfile(user_hostfiles[0],
1032: host, host_key, options.hash_known_hosts) &&
1033: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 1034: host_key, options.hash_known_hosts);
1035: } else {
1036: /* Add unhashed "host,ip" */
1.234 djm 1037: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 1038: hostline, host_key,
1039: options.hash_known_hosts);
1040: }
1041: } else {
1.234 djm 1042: r = add_host_to_hostfile(user_hostfiles[0], host,
1043: host_key, options.hash_known_hosts);
1.38 markus 1044: hostp = host;
1.161 djm 1045: }
1.38 markus 1046:
1.161 djm 1047: if (!r)
1.138 itojun 1048: logit("Failed to add the host to the list of known "
1.234 djm 1049: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 1050: else
1.138 itojun 1051: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 1052: "list of known hosts.", hostp, type);
1.38 markus 1053: break;
1.220 djm 1054: case HOST_REVOKED:
1055: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1056: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1057: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1058: error("The %s host key for %s is marked as revoked.", type, host);
1059: error("This could mean that a stolen key is being used to");
1060: error("impersonate this host.");
1061:
1062: /*
1063: * If strict host key checking is in use, the user will have
1064: * to edit the key manually and we can only abort.
1065: */
1.285 djm 1066: if (options.strict_host_key_checking !=
1067: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 1068: error("%s host key for %.200s was revoked and you have "
1069: "requested strict checking.", type, host);
1070: goto fail;
1071: }
1072: goto continue_unsafe;
1073:
1.38 markus 1074: case HOST_CHANGED:
1.219 djm 1075: if (want_cert) {
1076: /*
1077: * This is only a debug() since it is valid to have
1078: * CAs with wildcard DNS matches that don't match
1079: * all hosts that one might visit.
1080: */
1081: debug("Host certificate authority does not "
1.229 djm 1082: "match %s in %s:%lu", CA_MARKER,
1083: host_found->file, host_found->line);
1.219 djm 1084: goto fail;
1085: }
1.197 dtucker 1086: if (readonly == ROQUIET)
1087: goto fail;
1.38 markus 1088: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1089: char *key_msg;
1.38 markus 1090: if (ip_status == HOST_NEW)
1.158 avsm 1091: key_msg = "is unknown";
1.38 markus 1092: else if (ip_status == HOST_OK)
1.158 avsm 1093: key_msg = "is unchanged";
1.38 markus 1094: else
1.158 avsm 1095: key_msg = "has a different value";
1.38 markus 1096: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1097: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1098: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1099: error("The %s host key for %s has changed,", type, host);
1.208 ian 1100: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1101: error("%s. This could either mean that", key_msg);
1.38 markus 1102: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1103: error("and its host key have changed at the same time.");
1.88 markus 1104: if (ip_status != HOST_NEW)
1.229 djm 1105: error("Offending key for IP in %s:%lu",
1106: ip_found->file, ip_found->line);
1.38 markus 1107: }
1108: /* The host key has changed. */
1.150 jakob 1109: warn_changed_key(host_key);
1.38 markus 1110: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1111: user_hostfiles[0]);
1.280 markus 1112: error("Offending %s key in %s:%lu",
1113: sshkey_type(host_found->key),
1.229 djm 1114: host_found->file, host_found->line);
1.38 markus 1115:
1.40 markus 1116: /*
1117: * If strict host key checking is in use, the user will have
1118: * to edit the key manually and we can only abort.
1119: */
1.285 djm 1120: if (options.strict_host_key_checking !=
1121: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 1122: error("%s host key for %.200s has changed and you have "
1123: "requested strict checking.", type, host);
1124: goto fail;
1125: }
1.38 markus 1126:
1.220 djm 1127: continue_unsafe:
1.40 markus 1128: /*
1129: * If strict host key checking has not been requested, allow
1.144 djm 1130: * the connection but without MITM-able authentication or
1.194 stevesk 1131: * forwarding.
1.40 markus 1132: */
1.38 markus 1133: if (options.password_authentication) {
1.108 markus 1134: error("Password authentication is disabled to avoid "
1135: "man-in-the-middle attacks.");
1.38 markus 1136: options.password_authentication = 0;
1.210 dtucker 1137: cancelled_forwarding = 1;
1.144 djm 1138: }
1139: if (options.kbd_interactive_authentication) {
1140: error("Keyboard-interactive authentication is disabled"
1141: " to avoid man-in-the-middle attacks.");
1142: options.kbd_interactive_authentication = 0;
1143: options.challenge_response_authentication = 0;
1.210 dtucker 1144: cancelled_forwarding = 1;
1.144 djm 1145: }
1146: if (options.challenge_response_authentication) {
1147: error("Challenge/response authentication is disabled"
1148: " to avoid man-in-the-middle attacks.");
1149: options.challenge_response_authentication = 0;
1.210 dtucker 1150: cancelled_forwarding = 1;
1.38 markus 1151: }
1152: if (options.forward_agent) {
1.108 markus 1153: error("Agent forwarding is disabled to avoid "
1154: "man-in-the-middle attacks.");
1.38 markus 1155: options.forward_agent = 0;
1.210 dtucker 1156: cancelled_forwarding = 1;
1.83 markus 1157: }
1158: if (options.forward_x11) {
1.108 markus 1159: error("X11 forwarding is disabled to avoid "
1160: "man-in-the-middle attacks.");
1.83 markus 1161: options.forward_x11 = 0;
1.210 dtucker 1162: cancelled_forwarding = 1;
1.83 markus 1163: }
1.108 markus 1164: if (options.num_local_forwards > 0 ||
1165: options.num_remote_forwards > 0) {
1166: error("Port forwarding is disabled to avoid "
1167: "man-in-the-middle attacks.");
1168: options.num_local_forwards =
1.118 deraadt 1169: options.num_remote_forwards = 0;
1.210 dtucker 1170: cancelled_forwarding = 1;
1.194 stevesk 1171: }
1172: if (options.tun_open != SSH_TUNMODE_NO) {
1173: error("Tunnel forwarding is disabled to avoid "
1174: "man-in-the-middle attacks.");
1175: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1176: cancelled_forwarding = 1;
1.38 markus 1177: }
1.210 dtucker 1178: if (options.exit_on_forward_failure && cancelled_forwarding)
1179: fatal("Error: forwarding disabled due to host key "
1180: "check failure");
1181:
1.40 markus 1182: /*
1183: * XXX Should permit the user to change to use the new id.
1184: * This could be done by converting the host key to an
1185: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1186: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1187: * accept the authentication.
1188: */
1.38 markus 1189: break;
1.132 markus 1190: case HOST_FOUND:
1191: fatal("internal error");
1192: break;
1.88 markus 1193: }
1194:
1195: if (options.check_host_ip && host_status != HOST_CHANGED &&
1196: ip_status == HOST_CHANGED) {
1.119 markus 1197: snprintf(msg, sizeof(msg),
1198: "Warning: the %s host key for '%.200s' "
1199: "differs from the key for the IP address '%.128s'"
1.229 djm 1200: "\nOffending key for IP in %s:%lu",
1201: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1202: if (host_status == HOST_OK) {
1203: len = strlen(msg);
1204: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1205: "\nMatching host key in %s:%lu",
1206: host_found->file, host_found->line);
1.119 markus 1207: }
1.285 djm 1208: if (options.strict_host_key_checking ==
1209: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1210: strlcat(msg, "\nAre you sure you want "
1211: "to continue connecting (yes/no)? ", sizeof(msg));
1212: if (!confirm(msg))
1.108 markus 1213: goto fail;
1.285 djm 1214: } else if (options.strict_host_key_checking !=
1215: SSH_STRICT_HOSTKEY_OFF) {
1216: logit("%s", msg);
1217: error("Exiting, you have requested strict checking.");
1218: goto fail;
1.119 markus 1219: } else {
1.143 djm 1220: logit("%s", msg);
1.88 markus 1221: }
1.257 djm 1222: }
1223:
1224: if (!hostkey_trusted && options.update_hostkeys) {
1225: debug("%s: hostkey not known or explicitly trusted: "
1226: "disabling UpdateHostkeys", __func__);
1227: options.update_hostkeys = 0;
1.38 markus 1228: }
1.82 provos 1229:
1.238 djm 1230: free(ip);
1231: free(host);
1.229 djm 1232: if (host_hostkeys != NULL)
1233: free_hostkeys(host_hostkeys);
1234: if (ip_hostkeys != NULL)
1235: free_hostkeys(ip_hostkeys);
1.108 markus 1236: return 0;
1237:
1238: fail:
1.220 djm 1239: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1240: /*
1241: * No matching certificate. Downgrade cert to raw key and
1242: * search normally.
1243: */
1244: debug("No matching CA found. Retry with plain key");
1.280 markus 1245: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1246: fatal("%s: sshkey_from_private: %s",
1247: __func__, ssh_err(r));
1248: if ((r = sshkey_drop_cert(raw_key)) != 0)
1249: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1250: host_key = raw_key;
1251: goto retry;
1252: }
1.293 dtucker 1253: sshkey_free(raw_key);
1.238 djm 1254: free(ip);
1255: free(host);
1.229 djm 1256: if (host_hostkeys != NULL)
1257: free_hostkeys(host_hostkeys);
1258: if (ip_hostkeys != NULL)
1259: free_hostkeys(ip_hostkeys);
1.108 markus 1260: return -1;
1261: }
1262:
1.140 jakob 1263: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1264: int
1.279 markus 1265: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1266: {
1.267 djm 1267: u_int i;
1.250 djm 1268: int r = -1, flags = 0;
1.267 djm 1269: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1270: struct sshkey *plain = NULL;
1.229 djm 1271:
1.252 djm 1272: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1273: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1274: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1275: r = -1;
1276: goto out;
1277: }
1278:
1.267 djm 1279: if (sshkey_is_cert(host_key)) {
1280: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1281: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1282: error("%s: fingerprint CA key: %s",
1283: __func__, ssh_err(r));
1284: r = -1;
1285: goto out;
1286: }
1287: sshkey_format_cert_validity(host_key->cert,
1288: valid, sizeof(valid));
1289: debug("Server host certificate: %s %s, serial %llu "
1290: "ID \"%s\" CA %s %s valid %s",
1291: sshkey_ssh_name(host_key), fp,
1.269 djm 1292: (unsigned long long)host_key->cert->serial,
1293: host_key->cert->key_id,
1.267 djm 1294: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1295: valid);
1296: for (i = 0; i < host_key->cert->nprincipals; i++) {
1297: debug2("Server host certificate hostname: %s",
1298: host_key->cert->principals[i]);
1299: }
1300: } else {
1.276 djm 1301: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1302: }
1.252 djm 1303:
1304: if (sshkey_equal(previous_host_key, host_key)) {
1305: debug2("%s: server host key %s %s matches cached key",
1306: __func__, sshkey_type(host_key), fp);
1307: r = 0;
1308: goto out;
1309: }
1310:
1311: /* Check in RevokedHostKeys file if specified */
1312: if (options.revoked_host_keys != NULL) {
1313: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1314: switch (r) {
1315: case 0:
1316: break; /* not revoked */
1317: case SSH_ERR_KEY_REVOKED:
1318: error("Host key %s %s revoked by file %s",
1319: sshkey_type(host_key), fp,
1320: options.revoked_host_keys);
1321: r = -1;
1322: goto out;
1323: default:
1324: error("Error checking host key %s %s in "
1325: "revoked keys file %s: %s", sshkey_type(host_key),
1326: fp, options.revoked_host_keys, ssh_err(r));
1327: r = -1;
1328: goto out;
1329: }
1.250 djm 1330: }
1331:
1.247 djm 1332: if (options.verify_host_key_dns) {
1333: /*
1334: * XXX certs are not yet supported for DNS, so downgrade
1335: * them and try the plain key.
1336: */
1.252 djm 1337: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1338: goto out;
1339: if (sshkey_is_cert(plain))
1340: sshkey_drop_cert(plain);
1.247 djm 1341: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1342: if (flags & DNS_VERIFY_FOUND) {
1343: if (options.verify_host_key_dns == 1 &&
1344: flags & DNS_VERIFY_MATCH &&
1345: flags & DNS_VERIFY_SECURE) {
1.250 djm 1346: r = 0;
1.252 djm 1347: goto out;
1.247 djm 1348: }
1349: if (flags & DNS_VERIFY_MATCH) {
1350: matching_host_key_dns = 1;
1351: } else {
1.287 djm 1352: warn_changed_key(plain);
1353: error("Update the SSHFP RR in DNS "
1354: "with the new host key to get rid "
1355: "of this message.");
1.247 djm 1356: }
1.153 jakob 1357: }
1.140 jakob 1358: }
1359: }
1.250 djm 1360: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1361: options.user_hostfiles, options.num_user_hostfiles,
1362: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1363:
1.252 djm 1364: out:
1365: sshkey_free(plain);
1366: free(fp);
1.267 djm 1367: free(cafp);
1.250 djm 1368: if (r == 0 && host_key != NULL) {
1.280 markus 1369: sshkey_free(previous_host_key);
1370: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1371: }
1372:
1373: return r;
1.51 markus 1374: }
1.70 markus 1375:
1.51 markus 1376: /*
1377: * Starts a dialog with the server, and authenticates the current user on the
1378: * server. This does not need any extra privileges. The basic connection
1379: * to the server must already have been established before this is called.
1380: * If login fails, this function prints an error and never returns.
1381: * This function does not require super-user privileges.
1382: */
1383: void
1.120 markus 1384: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1385: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1386: {
1.241 djm 1387: char *host;
1.70 markus 1388: char *server_user, *local_user;
1389:
1390: local_user = xstrdup(pw->pw_name);
1391: server_user = options.user ? options.user : local_user;
1.51 markus 1392:
1393: /* Convert the user-supplied hostname into all lowercase. */
1394: host = xstrdup(orighost);
1.241 djm 1395: lowercase(host);
1.51 markus 1396:
1397: /* Exchange protocol version identification strings with the server. */
1.202 djm 1398: ssh_exchange_identification(timeout_ms);
1.51 markus 1399:
1400: /* Put the connection into non-blocking mode. */
1401: packet_set_nonblocking();
1402:
1403: /* key exchange */
1404: /* authenticate user */
1.261 dtucker 1405: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.276 djm 1406: ssh_kex2(host, hostaddr, port);
1407: ssh_userauth2(local_user, server_user, host, sensitive);
1.238 djm 1408: free(local_user);
1.97 markus 1409: }
1410:
1411: void
1412: ssh_put_password(char *password)
1413: {
1414: int size;
1415: char *padded;
1416:
1.99 deraadt 1417: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1418: packet_put_cstring(password);
1.99 deraadt 1419: return;
1420: }
1.272 deraadt 1421: size = ROUNDUP(strlen(password) + 1, 32);
1.179 djm 1422: padded = xcalloc(1, size);
1.97 markus 1423: strlcpy(padded, password, size);
1424: packet_put_string(padded, size);
1.245 djm 1425: explicit_bzero(padded, size);
1.238 djm 1426: free(padded);
1.132 markus 1427: }
1428:
1429: /* print all known host keys for a given host, but skip keys of given type */
1430: static int
1.279 markus 1431: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1432: {
1.242 djm 1433: int type[] = {
1434: KEY_RSA,
1435: KEY_DSA,
1436: KEY_ECDSA,
1437: KEY_ED25519,
1.297 markus 1438: KEY_XMSS,
1.242 djm 1439: -1
1440: };
1.229 djm 1441: int i, ret = 0;
1442: char *fp, *ra;
1443: const struct hostkey_entry *found;
1.132 markus 1444:
1445: for (i = 0; type[i] != -1; i++) {
1446: if (type[i] == key->type)
1447: continue;
1.229 djm 1448: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1449: continue;
1.259 djm 1450: fp = sshkey_fingerprint(found->key,
1.254 djm 1451: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1452: ra = sshkey_fingerprint(found->key,
1.254 djm 1453: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1454: if (fp == NULL || ra == NULL)
1455: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1456: logit("WARNING: %s key found for host %s\n"
1457: "in %s:%lu\n"
1458: "%s key fingerprint %s.",
1459: key_type(found->key),
1460: found->host, found->file, found->line,
1461: key_type(found->key), fp);
1462: if (options.visual_host_key)
1463: logit("%s", ra);
1.238 djm 1464: free(ra);
1465: free(fp);
1.229 djm 1466: ret = 1;
1.132 markus 1467: }
1.229 djm 1468: return ret;
1.150 jakob 1469: }
1470:
1471: static void
1.279 markus 1472: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1473: {
1474: char *fp;
1475:
1.259 djm 1476: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1477: SSH_FP_DEFAULT);
1.259 djm 1478: if (fp == NULL)
1479: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1480:
1481: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1482: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1483: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1484: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1485: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1486: error("It is also possible that a host key has just been changed.");
1.150 jakob 1487: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.287 djm 1488: key_type(host_key), fp);
1.150 jakob 1489: error("Please contact your system administrator.");
1490:
1.238 djm 1491: free(fp);
1.171 reyk 1492: }
1493:
1494: /*
1495: * Execute a local command
1496: */
1497: int
1498: ssh_local_cmd(const char *args)
1499: {
1500: char *shell;
1501: pid_t pid;
1502: int status;
1.231 djm 1503: void (*osighand)(int);
1.171 reyk 1504:
1505: if (!options.permit_local_command ||
1506: args == NULL || !*args)
1507: return (1);
1508:
1.226 djm 1509: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1510: shell = _PATH_BSHELL;
1511:
1.231 djm 1512: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1513: pid = fork();
1514: if (pid == 0) {
1.232 djm 1515: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1516: debug3("Executing %s -c \"%s\"", shell, args);
1517: execl(shell, shell, "-c", args, (char *)NULL);
1518: error("Couldn't execute %s -c \"%s\": %s",
1519: shell, args, strerror(errno));
1520: _exit(1);
1521: } else if (pid == -1)
1522: fatal("fork failed: %.100s", strerror(errno));
1523: while (waitpid(pid, &status, 0) == -1)
1524: if (errno != EINTR)
1525: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1526: signal(SIGCHLD, osighand);
1.171 reyk 1527:
1528: if (!WIFEXITED(status))
1529: return (1);
1530:
1531: return (WEXITSTATUS(status));
1.266 jcs 1532: }
1533:
1534: void
1.294 djm 1535: maybe_add_key_to_agent(char *authfile, const struct sshkey *private,
1536: char *comment, char *passphrase)
1.266 jcs 1537: {
1538: int auth_sock = -1, r;
1539:
1540: if (options.add_keys_to_agent == 0)
1541: return;
1542:
1543: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1544: debug3("no authentication agent, not adding key");
1545: return;
1546: }
1547:
1548: if (options.add_keys_to_agent == 2 &&
1549: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1550: debug3("user denied adding this key");
1.273 dtucker 1551: close(auth_sock);
1.266 jcs 1552: return;
1553: }
1554:
1555: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1.297 markus 1556: (options.add_keys_to_agent == 3), 0)) == 0)
1.266 jcs 1557: debug("identity added to agent: %s", authfile);
1558: else
1559: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1560: close(auth_sock);
1.1 deraadt 1561: }