Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.335
1.335 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.334 2020/10/03 09:22:26 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>
1.199 deraadt 30: #include <signal.h>
1.188 stevesk 31: #include <pwd.h>
1.198 stevesk 32: #include <stdio.h>
1.196 stevesk 33: #include <stdlib.h>
1.323 deraadt 34: #include <stdarg.h>
1.193 stevesk 35: #include <string.h>
1.192 stevesk 36: #include <unistd.h>
1.295 djm 37: #include <ifaddrs.h>
1.71 markus 38:
1.199 deraadt 39: #include "xmalloc.h"
1.91 markus 40: #include "ssh.h"
1.299 markus 41: #include "sshbuf.h"
1.1 deraadt 42: #include "packet.h"
1.21 markus 43: #include "compat.h"
1.300 markus 44: #include "sshkey.h"
1.71 markus 45: #include "sshconnect.h"
1.58 markus 46: #include "hostfile.h"
1.91 markus 47: #include "log.h"
1.251 millert 48: #include "misc.h"
1.91 markus 49: #include "readconf.h"
50: #include "atomicio.h"
1.140 jakob 51: #include "dns.h"
1.239 djm 52: #include "monitor_fdpass.h"
1.219 djm 53: #include "ssh2.h"
1.186 stevesk 54: #include "version.h"
1.252 djm 55: #include "authfile.h"
56: #include "ssherr.h"
1.266 jcs 57: #include "authfd.h"
1.309 djm 58: #include "kex.h"
1.310 djm 59:
1.279 markus 60: struct sshkey *previous_host_key = NULL;
1.59 markus 61:
1.169 stevesk 62: static int matching_host_key_dns = 0;
1.145 jakob 63:
1.227 djm 64: static pid_t proxy_command_pid = 0;
65:
1.124 markus 66: /* import */
1.307 djm 67: extern int debug_flag;
1.43 markus 68: extern Options options;
1.50 markus 69: extern char *__progname;
1.91 markus 70:
1.279 markus 71: static int show_other_keys(struct hostkeys *, struct sshkey *);
72: static void warn_changed_key(struct sshkey *);
1.132 markus 73:
1.239 djm 74: /* Expand a proxy command */
75: static char *
76: expand_proxy_command(const char *proxy_command, const char *user,
1.325 naddy 77: const char *host, const char *host_arg, int port)
1.239 djm 78: {
79: char *tmp, *ret, strport[NI_MAXSERV];
1.330 dtucker 80: const char *keyalias = options.host_key_alias ?
81: options.host_key_alias : host_arg;
1.239 djm 82:
1.241 djm 83: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 84: xasprintf(&tmp, "exec %s", proxy_command);
1.318 djm 85: ret = percent_expand(tmp,
86: "h", host,
1.330 dtucker 87: "k", keyalias,
1.318 djm 88: "n", host_arg,
89: "p", strport,
90: "r", options.user,
91: (char *)NULL);
1.239 djm 92: free(tmp);
93: return ret;
94: }
95:
96: /*
97: * Connect to the given ssh server using a proxy command that passes a
98: * a connected fd back to us.
99: */
100: static int
1.318 djm 101: ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host,
102: const char *host_arg, u_short port, const char *proxy_command)
1.239 djm 103: {
104: char *command_string;
105: int sp[2], sock;
106: pid_t pid;
107: char *shell;
108:
109: if ((shell = getenv("SHELL")) == NULL)
110: shell = _PATH_BSHELL;
111:
1.317 deraadt 112: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) == -1)
1.239 djm 113: fatal("Could not create socketpair to communicate with "
114: "proxy dialer: %.100s", strerror(errno));
115:
116: command_string = expand_proxy_command(proxy_command, options.user,
1.325 naddy 117: host, host_arg, port);
1.239 djm 118: debug("Executing proxy dialer command: %.500s", command_string);
119:
120: /* Fork and execute the proxy command. */
121: if ((pid = fork()) == 0) {
122: char *argv[10];
123:
124: close(sp[1]);
125: /* Redirect stdin and stdout. */
126: if (sp[0] != 0) {
1.317 deraadt 127: if (dup2(sp[0], 0) == -1)
1.239 djm 128: perror("dup2 stdin");
129: }
130: if (sp[0] != 1) {
1.317 deraadt 131: if (dup2(sp[0], 1) == -1)
1.239 djm 132: perror("dup2 stdout");
133: }
134: if (sp[0] >= 2)
135: close(sp[0]);
136:
137: /*
1.307 djm 138: * Stderr is left for non-ControlPersist connections is so
139: * error messages may be printed on the user's terminal.
1.239 djm 140: */
1.308 dtucker 141: if (!debug_flag && options.control_path != NULL &&
1.334 djm 142: options.control_persist && stdfd_devnull(0, 0, 1) == -1)
143: error("%s: stdfd_devnull failed", __func__);
1.307 djm 144:
1.239 djm 145: argv[0] = shell;
146: argv[1] = "-c";
147: argv[2] = command_string;
148: argv[3] = NULL;
149:
150: /*
151: * Execute the proxy command.
152: * Note that we gave up any extra privileges above.
153: */
154: execv(argv[0], argv);
155: perror(argv[0]);
156: exit(1);
157: }
158: /* Parent. */
1.317 deraadt 159: if (pid == -1)
1.239 djm 160: fatal("fork failed: %.100s", strerror(errno));
161: close(sp[0]);
162: free(command_string);
163:
164: if ((sock = mm_receive_fd(sp[1])) == -1)
165: fatal("proxy dialer did not pass back a connection");
1.271 markus 166: close(sp[1]);
1.239 djm 167:
168: while (waitpid(pid, NULL, 0) == -1)
169: if (errno != EINTR)
170: fatal("Couldn't wait for child: %s", strerror(errno));
171:
172: /* Set the connection file descriptors. */
1.286 djm 173: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
174: return -1; /* ssh_packet_set_connection logs error */
1.239 djm 175:
176: return 0;
177: }
178:
1.39 deraadt 179: /*
180: * Connect to the given ssh server using a proxy command.
181: */
1.109 itojun 182: static int
1.318 djm 183: ssh_proxy_connect(struct ssh *ssh, const char *host, const char *host_arg,
184: u_short port, const char *proxy_command)
1.1 deraadt 185: {
1.239 djm 186: char *command_string;
1.38 markus 187: int pin[2], pout[2];
1.69 deraadt 188: pid_t pid;
1.239 djm 189: char *shell;
1.237 markus 190:
1.226 djm 191: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 192: shell = _PATH_BSHELL;
1.38 markus 193:
194: /* Create pipes for communicating with the proxy. */
1.317 deraadt 195: if (pipe(pin) == -1 || pipe(pout) == -1)
1.38 markus 196: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 197: strerror(errno));
1.38 markus 198:
1.239 djm 199: command_string = expand_proxy_command(proxy_command, options.user,
1.325 naddy 200: host, host_arg, port);
1.38 markus 201: debug("Executing proxy command: %.500s", command_string);
202:
203: /* Fork and execute the proxy command. */
204: if ((pid = fork()) == 0) {
205: char *argv[10];
206:
207: /* Redirect stdin and stdout. */
208: close(pin[1]);
209: if (pin[0] != 0) {
1.317 deraadt 210: if (dup2(pin[0], 0) == -1)
1.38 markus 211: perror("dup2 stdin");
212: close(pin[0]);
213: }
214: close(pout[0]);
1.317 deraadt 215: if (dup2(pout[1], 1) == -1)
1.38 markus 216: perror("dup2 stdout");
217: /* Cannot be 1 because pin allocated two descriptors. */
218: close(pout[1]);
219:
1.307 djm 220: /*
221: * Stderr is left for non-ControlPersist connections is so
222: * error messages may be printed on the user's terminal.
223: */
1.308 dtucker 224: if (!debug_flag && options.control_path != NULL &&
1.334 djm 225: options.control_persist && stdfd_devnull(0, 0, 1) == -1)
226: error("%s: stdfd_devnull failed", __func__);
1.307 djm 227:
1.201 djm 228: argv[0] = shell;
1.38 markus 229: argv[1] = "-c";
230: argv[2] = command_string;
231: argv[3] = NULL;
232:
233: /* Execute the proxy command. Note that we gave up any
234: extra privileges above. */
1.327 dtucker 235: ssh_signal(SIGPIPE, SIG_DFL);
1.89 markus 236: execv(argv[0], argv);
237: perror(argv[0]);
1.38 markus 238: exit(1);
239: }
240: /* Parent. */
1.317 deraadt 241: if (pid == -1)
1.38 markus 242: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 243: else
244: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 245:
246: /* Close child side of the descriptors. */
247: close(pin[0]);
248: close(pout[1]);
249:
250: /* Free the command name. */
1.238 djm 251: free(command_string);
1.38 markus 252:
253: /* Set the connection file descriptors. */
1.286 djm 254: if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
255: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 256:
1.110 markus 257: return 0;
1.227 djm 258: }
259:
260: void
261: ssh_kill_proxy_command(void)
262: {
263: /*
264: * Send SIGHUP to proxy command if used. We don't wait() in
265: * case it hangs and instead rely on init to reap the child
266: */
267: if (proxy_command_pid > 1)
1.228 djm 268: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 269: }
270:
1.39 deraadt 271: /*
1.295 djm 272: * Search a interface address list (returned from getifaddrs(3)) for an
1.298 djm 273: * address that matches the desired address family on the specified interface.
1.295 djm 274: * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure.
275: */
276: static int
277: check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs,
278: struct sockaddr_storage *resultp, socklen_t *rlenp)
279: {
280: struct sockaddr_in6 *sa6;
281: struct sockaddr_in *sa;
282: struct in6_addr *v6addr;
283: const struct ifaddrs *ifa;
284: int allow_local;
285:
286: /*
287: * Prefer addresses that are not loopback or linklocal, but use them
288: * if nothing else matches.
289: */
290: for (allow_local = 0; allow_local < 2; allow_local++) {
291: for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
292: if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL ||
293: (ifa->ifa_flags & IFF_UP) == 0 ||
294: ifa->ifa_addr->sa_family != af ||
295: strcmp(ifa->ifa_name, options.bind_interface) != 0)
296: continue;
297: switch (ifa->ifa_addr->sa_family) {
298: case AF_INET:
299: sa = (struct sockaddr_in *)ifa->ifa_addr;
300: if (!allow_local && sa->sin_addr.s_addr ==
301: htonl(INADDR_LOOPBACK))
302: continue;
303: if (*rlenp < sizeof(struct sockaddr_in)) {
304: error("%s: v4 addr doesn't fit",
305: __func__);
306: return -1;
307: }
308: *rlenp = sizeof(struct sockaddr_in);
309: memcpy(resultp, sa, *rlenp);
310: return 0;
311: case AF_INET6:
312: sa6 = (struct sockaddr_in6 *)ifa->ifa_addr;
313: v6addr = &sa6->sin6_addr;
314: if (!allow_local &&
315: (IN6_IS_ADDR_LINKLOCAL(v6addr) ||
316: IN6_IS_ADDR_LOOPBACK(v6addr)))
317: continue;
318: if (*rlenp < sizeof(struct sockaddr_in6)) {
319: error("%s: v6 addr doesn't fit",
320: __func__);
321: return -1;
322: }
323: *rlenp = sizeof(struct sockaddr_in6);
324: memcpy(resultp, sa6, *rlenp);
325: return 0;
326: }
327: }
328: }
329: return -1;
330: }
331:
332: /*
1.303 dtucker 333: * Creates a socket for use as the ssh connection.
1.39 deraadt 334: */
1.109 itojun 335: static int
1.302 dtucker 336: ssh_create_socket(struct addrinfo *ai)
1.1 deraadt 337: {
1.301 dtucker 338: int sock, r;
1.295 djm 339: struct sockaddr_storage bindaddr;
340: socklen_t bindaddrlen = 0;
1.246 djm 341: struct addrinfo hints, *res = NULL;
1.295 djm 342: struct ifaddrs *ifaddrs = NULL;
343: char ntop[NI_MAXHOST];
1.1 deraadt 344:
1.217 dtucker 345: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.317 deraadt 346: if (sock == -1) {
1.240 djm 347: error("socket: %s", strerror(errno));
1.216 dtucker 348: return -1;
349: }
350: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 351:
352: /* Bind the socket to an alternative local IP address */
1.302 dtucker 353: if (options.bind_address == NULL && options.bind_interface == NULL)
1.105 markus 354: return sock;
355:
1.295 djm 356: if (options.bind_address != NULL) {
1.246 djm 357: memset(&hints, 0, sizeof(hints));
358: hints.ai_family = ai->ai_family;
359: hints.ai_socktype = ai->ai_socktype;
360: hints.ai_protocol = ai->ai_protocol;
361: hints.ai_flags = AI_PASSIVE;
1.295 djm 362: if ((r = getaddrinfo(options.bind_address, NULL,
363: &hints, &res)) != 0) {
1.246 djm 364: error("getaddrinfo: %s: %s", options.bind_address,
1.295 djm 365: ssh_gai_strerror(r));
366: goto fail;
367: }
1.296 dtucker 368: if (res == NULL) {
1.295 djm 369: error("getaddrinfo: no addrs");
370: goto fail;
371: }
372: memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
373: bindaddrlen = res->ai_addrlen;
374: } else if (options.bind_interface != NULL) {
375: if ((r = getifaddrs(&ifaddrs)) != 0) {
376: error("getifaddrs: %s: %s", options.bind_interface,
377: strerror(errno));
378: goto fail;
379: }
380: bindaddrlen = sizeof(bindaddr);
381: if (check_ifaddrs(options.bind_interface, ai->ai_family,
382: ifaddrs, &bindaddr, &bindaddrlen) != 0) {
383: logit("getifaddrs: %s: no suitable addresses",
384: options.bind_interface);
385: goto fail;
1.246 djm 386: }
1.105 markus 387: }
1.295 djm 388: if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
389: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
390: error("%s: getnameinfo failed: %s", __func__,
391: ssh_gai_strerror(r));
392: goto fail;
393: }
1.301 dtucker 394: if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
1.295 djm 395: error("bind %s: %s", ntop, strerror(errno));
396: goto fail;
1.38 markus 397: }
1.295 djm 398: debug("%s: bound to %s", __func__, ntop);
399: /* success */
400: goto out;
401: fail:
402: close(sock);
403: sock = -1;
404: out:
1.246 djm 405: if (res != NULL)
406: freeaddrinfo(res);
1.295 djm 407: if (ifaddrs != NULL)
408: freeifaddrs(ifaddrs);
1.38 markus 409: return sock;
1.1 deraadt 410: }
411:
1.282 djm 412: /*
1.49 markus 413: * Opens a TCP/IP connection to the remote server on the given host.
414: * The address of the remote host will be returned in hostaddr.
1.302 dtucker 415: * If port is 0, the default port will be used.
1.39 deraadt 416: * Connection_attempts specifies the maximum number of tries (one per
417: * second). If proxy_command is non-NULL, it specifies the command (with %h
418: * and %p substituted for host and port, respectively) to use to contact
419: * the daemon.
420: */
1.241 djm 421: static int
1.286 djm 422: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.241 djm 423: struct sockaddr_storage *hostaddr, u_short port, int family,
1.302 dtucker 424: int connection_attempts, int *timeout_ms, int want_keepalive)
1.1 deraadt 425: {
1.313 dtucker 426: int on = 1, saved_timeout_ms = *timeout_ms;
1.290 djm 427: int oerrno, sock = -1, attempt;
1.90 markus 428: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 429: struct addrinfo *ai;
1.38 markus 430:
1.302 dtucker 431: debug2("%s", __func__);
1.268 djm 432: memset(ntop, 0, sizeof(ntop));
433: memset(strport, 0, sizeof(strport));
1.38 markus 434:
1.181 markus 435: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 436: if (attempt > 0) {
437: /* Sleep a moment before retrying. */
438: sleep(1);
1.38 markus 439: debug("Trying again...");
1.200 markus 440: }
1.181 markus 441: /*
442: * Loop through addresses for this host, and try each one in
443: * sequence until the connection succeeds.
444: */
1.49 markus 445: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 446: if (ai->ai_family != AF_INET &&
1.290 djm 447: ai->ai_family != AF_INET6) {
448: errno = EAFNOSUPPORT;
1.49 markus 449: continue;
1.290 djm 450: }
1.49 markus 451: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
452: ntop, sizeof(ntop), strport, sizeof(strport),
453: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.290 djm 454: oerrno = errno;
1.265 djm 455: error("%s: getnameinfo failed", __func__);
1.290 djm 456: errno = oerrno;
1.49 markus 457: continue;
458: }
459: debug("Connecting to %.200s [%.100s] port %s.",
460: host, ntop, strport);
461:
462: /* Create a socket for connecting. */
1.302 dtucker 463: sock = ssh_create_socket(ai);
1.292 stsp 464: if (sock < 0) {
1.110 markus 465: /* Any error is already output */
1.290 djm 466: errno = 0;
1.49 markus 467: continue;
1.292 stsp 468: }
1.49 markus 469:
1.313 dtucker 470: *timeout_ms = saved_timeout_ms;
1.141 djm 471: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 472: timeout_ms) >= 0) {
1.49 markus 473: /* Successful connection. */
1.102 markus 474: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 475: break;
1.49 markus 476: } else {
1.290 djm 477: oerrno = errno;
1.131 itojun 478: debug("connect to address %s port %s: %s",
479: ntop, strport, strerror(errno));
1.38 markus 480: close(sock);
1.181 markus 481: sock = -1;
1.290 djm 482: errno = oerrno;
1.38 markus 483: }
484: }
1.181 markus 485: if (sock != -1)
1.49 markus 486: break; /* Successful connection. */
1.38 markus 487: }
1.49 markus 488:
1.38 markus 489: /* Return failure if we didn't get a successful connection. */
1.181 markus 490: if (sock == -1) {
1.159 markus 491: error("ssh: connect to host %s port %s: %s",
1.290 djm 492: host, strport, errno == 0 ? "failure" : strerror(errno));
493: return -1;
1.130 itojun 494: }
1.38 markus 495:
496: debug("Connection established.");
1.90 markus 497:
1.155 markus 498: /* Set SO_KEEPALIVE if requested. */
1.202 djm 499: if (want_keepalive &&
1.90 markus 500: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1.317 deraadt 501: sizeof(on)) == -1)
1.90 markus 502: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 503:
504: /* Set the connection. */
1.286 djm 505: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
506: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 507:
1.319 djm 508: return 0;
1.59 markus 509: }
510:
1.241 djm 511: int
1.318 djm 512: ssh_connect(struct ssh *ssh, const char *host, const char *host_arg,
513: struct addrinfo *addrs, struct sockaddr_storage *hostaddr, u_short port,
514: int family, int connection_attempts, int *timeout_ms, int want_keepalive)
1.241 djm 515: {
1.314 markus 516: int in, out;
517:
1.241 djm 518: if (options.proxy_command == NULL) {
1.286 djm 519: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
1.302 dtucker 520: family, connection_attempts, timeout_ms, want_keepalive);
1.241 djm 521: } else if (strcmp(options.proxy_command, "-") == 0) {
1.317 deraadt 522: if ((in = dup(STDIN_FILENO)) == -1 ||
523: (out = dup(STDOUT_FILENO)) == -1) {
1.314 markus 524: if (in >= 0)
525: close(in);
526: error("%s: dup() in/out failed", __func__);
527: return -1; /* ssh_packet_set_connection logs error */
528: }
529: if ((ssh_packet_set_connection(ssh, in, out)) == NULL)
1.286 djm 530: return -1; /* ssh_packet_set_connection logs error */
531: return 0;
1.241 djm 532: } else if (options.proxy_use_fdpass) {
1.318 djm 533: return ssh_proxy_fdpass_connect(ssh, host, host_arg, port,
1.241 djm 534: options.proxy_command);
535: }
1.318 djm 536: return ssh_proxy_connect(ssh, host, host_arg, port,
537: options.proxy_command);
1.241 djm 538: }
539:
1.96 markus 540: /* defaults to 'no' */
1.109 itojun 541: static int
1.312 dtucker 542: confirm(const char *prompt, const char *fingerprint)
1.1 deraadt 543: {
1.119 markus 544: const char *msg, *again = "Please type 'yes' or 'no': ";
1.312 dtucker 545: const char *again_fp = "Please type 'yes', 'no' or the fingerprint: ";
1.326 dtucker 546: char *p, *cp;
1.119 markus 547: int ret = -1;
1.96 markus 548:
549: if (options.batch_mode)
550: return 0;
1.312 dtucker 551: for (msg = prompt;;msg = fingerprint ? again_fp : again) {
1.326 dtucker 552: cp = p = read_passphrase(msg, RP_ECHO);
1.289 djm 553: if (p == NULL)
554: return 0;
1.326 dtucker 555: p += strspn(p, " \t"); /* skip leading whitespace */
556: p[strcspn(p, " \t\n")] = '\0'; /* remove trailing whitespace */
1.289 djm 557: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 558: ret = 0;
1.312 dtucker 559: else if (strcasecmp(p, "yes") == 0 || (fingerprint != NULL &&
1.332 djm 560: strcmp(p, fingerprint) == 0))
1.119 markus 561: ret = 1;
1.326 dtucker 562: free(cp);
1.119 markus 563: if (ret != -1)
564: return ret;
1.1 deraadt 565: }
566: }
567:
1.219 djm 568: static int
1.305 djm 569: check_host_cert(const char *host, const struct sshkey *key)
1.219 djm 570: {
571: const char *reason;
1.305 djm 572: int r;
1.219 djm 573:
1.305 djm 574: if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) {
1.219 djm 575: error("%s", reason);
576: return 0;
577: }
1.305 djm 578: if (sshbuf_len(key->cert->critical) != 0) {
1.223 djm 579: error("Certificate for %s contains unsupported "
580: "critical options(s)", host);
1.219 djm 581: return 0;
582: }
1.305 djm 583: if ((r = sshkey_check_cert_sigtype(key,
584: options.ca_sign_algorithms)) != 0) {
585: logit("%s: certificate signature algorithm %s: %s", __func__,
586: (key->cert == NULL || key->cert->signature_type == NULL) ?
587: "(null)" : key->cert->signature_type, ssh_err(r));
588: return 0;
589: }
590:
1.219 djm 591: return 1;
592: }
593:
1.229 djm 594: static int
595: sockaddr_is_local(struct sockaddr *hostaddr)
596: {
597: switch (hostaddr->sa_family) {
598: case AF_INET:
599: return (ntohl(((struct sockaddr_in *)hostaddr)->
600: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
601: case AF_INET6:
602: return IN6_IS_ADDR_LOOPBACK(
603: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
604: default:
605: return 0;
606: }
607: }
608:
609: /*
610: * Prepare the hostname and ip address strings that are used to lookup
611: * host keys in known_hosts files. These may have a port number appended.
612: */
613: void
614: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
615: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
616: {
617: char ntop[NI_MAXHOST];
618:
619: /*
620: * We don't have the remote ip-address for connections
621: * using a proxy command
622: */
623: if (hostfile_ipaddr != NULL) {
624: if (options.proxy_command == NULL) {
625: if (getnameinfo(hostaddr, hostaddr->sa_len,
626: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 627: fatal("%s: getnameinfo failed", __func__);
1.229 djm 628: *hostfile_ipaddr = put_host_port(ntop, port);
629: } else {
630: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
631: "command>");
632: }
633: }
634:
635: /*
636: * Allow the user to record the key under a different name or
637: * differentiate a non-standard port. This is useful for ssh
638: * tunneling over forwarded connections or if you run multiple
639: * sshd's on different ports on the same machine.
640: */
641: if (hostfile_hostname != NULL) {
642: if (options.host_key_alias != NULL) {
643: *hostfile_hostname = xstrdup(options.host_key_alias);
644: debug("using hostkeyalias: %s", *hostfile_hostname);
645: } else {
646: *hostfile_hostname = put_host_port(hostname, port);
647: }
648: }
649: }
650:
1.39 deraadt 651: /*
1.108 markus 652: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 653: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.333 djm 654: *
655: * If cert_fallbackp is not NULL then will attempt to convert certificate host
656: * keys to plain keys if no certificate match was found and will return
657: * non-zero via *cert_fallbackp if this fall-back was used.
1.39 deraadt 658: */
1.197 dtucker 659: #define RDRW 0
660: #define RDONLY 1
661: #define ROQUIET 2
1.109 itojun 662: static int
1.197 dtucker 663: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 664: struct sshkey *host_key, int readonly,
1.234 djm 665: char **user_hostfiles, u_int num_user_hostfiles,
1.333 djm 666: char **system_hostfiles, u_int num_system_hostfiles, int *cert_fallbackp)
1.1 deraadt 667: {
1.234 djm 668: HostStatus host_status;
669: HostStatus ip_status;
1.279 markus 670: struct sshkey *raw_key = NULL;
1.189 dtucker 671: char *ip = NULL, *host = NULL;
1.204 grunk 672: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 673: char msg[1024];
1.234 djm 674: const char *type;
675: const struct hostkey_entry *host_found, *ip_found;
1.312 dtucker 676: int len, cancelled_forwarding = 0, confirmed;
1.333 djm 677: int local = sockaddr_is_local(hostaddr), cert_fallback = 0;
1.280 markus 678: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 679: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 680: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 681: u_int i;
1.49 markus 682:
1.333 djm 683: if (cert_fallbackp != NULL)
684: *cert_fallbackp = 0;
685:
1.49 markus 686: /*
687: * Force accepting of the host key for loopback/localhost. The
688: * problem is that if the home directory is NFS-mounted to multiple
689: * machines, localhost will refer to a different machine in each of
690: * them, and the user will get bogus HOST_CHANGED warnings. This
691: * essentially disables host authentication for localhost; however,
692: * this is probably not a real problem.
693: */
1.111 markus 694: if (options.no_host_authentication_for_localhost == 1 && local &&
695: options.host_key_alias == NULL) {
1.88 markus 696: debug("Forcing accepting of host key for "
697: "loopback/localhost.");
1.108 markus 698: return 0;
1.49 markus 699: }
1.42 markus 700:
701: /*
1.229 djm 702: * Prepare the hostname and address strings used for hostkey lookup.
703: * In some cases, these will have a port number appended.
1.42 markus 704: */
1.229 djm 705: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 706:
707: /*
1.88 markus 708: * Turn off check_host_ip if the connection is to localhost, via proxy
709: * command or if we don't have a hostname to compare with
710: */
1.189 dtucker 711: if (options.check_host_ip && (local ||
712: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 713: options.check_host_ip = 0;
1.86 markus 714:
1.229 djm 715: host_hostkeys = init_hostkeys();
1.234 djm 716: for (i = 0; i < num_user_hostfiles; i++)
717: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
718: for (i = 0; i < num_system_hostfiles; i++)
719: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 720:
721: ip_hostkeys = NULL;
722: if (!want_cert && options.check_host_ip) {
723: ip_hostkeys = init_hostkeys();
1.234 djm 724: for (i = 0; i < num_user_hostfiles; i++)
725: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
726: for (i = 0; i < num_system_hostfiles; i++)
727: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 728: }
1.38 markus 729:
1.219 djm 730: retry:
1.229 djm 731: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 732: want_cert = sshkey_is_cert(host_key);
733: type = sshkey_type(host_key);
1.219 djm 734:
1.46 markus 735: /*
1.170 djm 736: * Check if the host key is present in the user's list of known
1.40 markus 737: * hosts or in the systemwide list.
738: */
1.229 djm 739: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
740: &host_found);
741:
1.40 markus 742: /*
743: * Also perform check for the ip address, skip the check if we are
1.219 djm 744: * localhost, looking for a certificate, or the hostname was an ip
745: * address to begin with.
1.40 markus 746: */
1.229 djm 747: if (!want_cert && ip_hostkeys != NULL) {
748: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
749: &ip_found);
1.38 markus 750: if (host_status == HOST_CHANGED &&
1.319 djm 751: (ip_status != HOST_CHANGED ||
1.229 djm 752: (ip_found != NULL &&
1.280 markus 753: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 754: host_ip_differ = 1;
755: } else
756: ip_status = host_status;
757:
758: switch (host_status) {
759: case HOST_OK:
760: /* The host is known and the key matches. */
1.219 djm 761: debug("Host '%.200s' is known and matches the %s host %s.",
762: host, type, want_cert ? "certificate" : "key");
1.229 djm 763: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
764: host_found->file, host_found->line);
1.281 djm 765: if (want_cert &&
766: !check_host_cert(options.host_key_alias == NULL ?
767: hostname : options.host_key_alias, host_key))
1.219 djm 768: goto fail;
1.88 markus 769: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 770: if (readonly || want_cert)
1.138 itojun 771: logit("%s host key for IP address "
1.108 markus 772: "'%.128s' not in list of known hosts.",
773: type, ip);
1.234 djm 774: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 775: host_key, options.hash_known_hosts))
1.138 itojun 776: logit("Failed to add the %s host key for IP "
1.108 markus 777: "address '%.128s' to the list of known "
1.262 dtucker 778: "hosts (%.500s).", type, ip,
1.234 djm 779: user_hostfiles[0]);
1.88 markus 780: else
1.138 itojun 781: logit("Warning: Permanently added the %s host "
1.108 markus 782: "key for IP address '%.128s' to the list "
783: "of known hosts.", type, ip);
1.209 grunk 784: } else if (options.visual_host_key) {
1.259 djm 785: fp = sshkey_fingerprint(host_key,
1.254 djm 786: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 787: ra = sshkey_fingerprint(host_key,
1.254 djm 788: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 789: if (fp == NULL || ra == NULL)
790: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 791: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 792: free(ra);
793: free(fp);
1.38 markus 794: }
1.257 djm 795: hostkey_trusted = 1;
1.38 markus 796: break;
797: case HOST_NEW:
1.197 dtucker 798: if (options.host_key_alias == NULL && port != 0 &&
799: port != SSH_DEFAULT_PORT) {
800: debug("checking without port identifier");
1.333 djm 801: /*
802: * NB. do not perform cert->key fallback in this
803: * recursive call. Fallback will only be performed in
804: * the top-level call.
805: */
1.212 stevesk 806: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 807: ROQUIET, user_hostfiles, num_user_hostfiles,
1.333 djm 808: system_hostfiles, num_system_hostfiles,
809: NULL) == 0) {
1.197 dtucker 810: debug("found matching key w/out port");
811: break;
812: }
813: }
1.219 djm 814: if (readonly || want_cert)
1.108 markus 815: goto fail;
1.38 markus 816: /* The host is new. */
1.285 djm 817: if (options.strict_host_key_checking ==
818: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 819: /*
820: * User has requested strict host key checking. We
821: * will not add the host key automatically. The only
822: * alternative left is to abort.
823: */
824: error("No %s host key is known for %.200s and you "
825: "have requested strict checking.", type, host);
826: goto fail;
1.285 djm 827: } else if (options.strict_host_key_checking ==
828: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 829: char msg1[1024], msg2[1024];
830:
1.229 djm 831: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 832: snprintf(msg1, sizeof(msg1),
1.168 djm 833: "\nbut keys of different type are already"
834: " known for this host.");
1.145 jakob 835: else
836: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 837: /* The default */
1.259 djm 838: fp = sshkey_fingerprint(host_key,
1.254 djm 839: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 840: ra = sshkey_fingerprint(host_key,
1.254 djm 841: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 842: if (fp == NULL || ra == NULL)
843: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 844: msg2[0] = '\0';
845: if (options.verify_host_key_dns) {
1.153 jakob 846: if (matching_host_key_dns)
1.145 jakob 847: snprintf(msg2, sizeof(msg2),
848: "Matching host key fingerprint"
849: " found in DNS.\n");
850: else
851: snprintf(msg2, sizeof(msg2),
852: "No matching host key fingerprint"
853: " found in DNS.\n");
854: }
1.119 markus 855: snprintf(msg, sizeof(msg),
1.108 markus 856: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 857: "established%s\n"
1.209 grunk 858: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 859: "Are you sure you want to continue connecting "
1.312 dtucker 860: "(yes/no/[fingerprint])? ",
1.209 grunk 861: host, ip, msg1, type, fp,
862: options.visual_host_key ? "\n" : "",
863: options.visual_host_key ? ra : "",
864: msg2);
1.238 djm 865: free(ra);
1.312 dtucker 866: confirmed = confirm(msg, fp);
1.238 djm 867: free(fp);
1.312 dtucker 868: if (!confirmed)
1.108 markus 869: goto fail;
1.257 djm 870: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 871: }
1.161 djm 872: /*
1.285 djm 873: * If in "new" or "off" strict mode, add the key automatically
874: * to the local known_hosts file.
1.161 djm 875: */
1.88 markus 876: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 877: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 878: hostp = hostline;
1.161 djm 879: if (options.hash_known_hosts) {
880: /* Add hash of host and IP separately */
1.234 djm 881: r = add_host_to_hostfile(user_hostfiles[0],
882: host, host_key, options.hash_known_hosts) &&
883: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 884: host_key, options.hash_known_hosts);
885: } else {
886: /* Add unhashed "host,ip" */
1.234 djm 887: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 888: hostline, host_key,
889: options.hash_known_hosts);
890: }
891: } else {
1.234 djm 892: r = add_host_to_hostfile(user_hostfiles[0], host,
893: host_key, options.hash_known_hosts);
1.38 markus 894: hostp = host;
1.161 djm 895: }
1.38 markus 896:
1.161 djm 897: if (!r)
1.138 itojun 898: logit("Failed to add the host to the list of known "
1.234 djm 899: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 900: else
1.138 itojun 901: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 902: "list of known hosts.", hostp, type);
1.38 markus 903: break;
1.220 djm 904: case HOST_REVOKED:
905: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
906: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
907: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
908: error("The %s host key for %s is marked as revoked.", type, host);
909: error("This could mean that a stolen key is being used to");
910: error("impersonate this host.");
911:
912: /*
913: * If strict host key checking is in use, the user will have
914: * to edit the key manually and we can only abort.
915: */
1.285 djm 916: if (options.strict_host_key_checking !=
917: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 918: error("%s host key for %.200s was revoked and you have "
919: "requested strict checking.", type, host);
920: goto fail;
921: }
922: goto continue_unsafe;
923:
1.38 markus 924: case HOST_CHANGED:
1.219 djm 925: if (want_cert) {
926: /*
927: * This is only a debug() since it is valid to have
928: * CAs with wildcard DNS matches that don't match
929: * all hosts that one might visit.
930: */
931: debug("Host certificate authority does not "
1.229 djm 932: "match %s in %s:%lu", CA_MARKER,
933: host_found->file, host_found->line);
1.219 djm 934: goto fail;
935: }
1.197 dtucker 936: if (readonly == ROQUIET)
937: goto fail;
1.38 markus 938: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 939: char *key_msg;
1.38 markus 940: if (ip_status == HOST_NEW)
1.158 avsm 941: key_msg = "is unknown";
1.38 markus 942: else if (ip_status == HOST_OK)
1.158 avsm 943: key_msg = "is unchanged";
1.38 markus 944: else
1.158 avsm 945: key_msg = "has a different value";
1.38 markus 946: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
947: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
948: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 949: error("The %s host key for %s has changed,", type, host);
1.208 ian 950: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 951: error("%s. This could either mean that", key_msg);
1.38 markus 952: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 953: error("and its host key have changed at the same time.");
1.88 markus 954: if (ip_status != HOST_NEW)
1.229 djm 955: error("Offending key for IP in %s:%lu",
956: ip_found->file, ip_found->line);
1.38 markus 957: }
958: /* The host key has changed. */
1.150 jakob 959: warn_changed_key(host_key);
1.38 markus 960: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 961: user_hostfiles[0]);
1.280 markus 962: error("Offending %s key in %s:%lu",
963: sshkey_type(host_found->key),
1.229 djm 964: host_found->file, host_found->line);
1.38 markus 965:
1.40 markus 966: /*
967: * If strict host key checking is in use, the user will have
968: * to edit the key manually and we can only abort.
969: */
1.285 djm 970: if (options.strict_host_key_checking !=
971: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 972: error("%s host key for %.200s has changed and you have "
973: "requested strict checking.", type, host);
974: goto fail;
975: }
1.38 markus 976:
1.220 djm 977: continue_unsafe:
1.40 markus 978: /*
979: * If strict host key checking has not been requested, allow
1.144 djm 980: * the connection but without MITM-able authentication or
1.194 stevesk 981: * forwarding.
1.40 markus 982: */
1.38 markus 983: if (options.password_authentication) {
1.108 markus 984: error("Password authentication is disabled to avoid "
985: "man-in-the-middle attacks.");
1.38 markus 986: options.password_authentication = 0;
1.210 dtucker 987: cancelled_forwarding = 1;
1.144 djm 988: }
989: if (options.kbd_interactive_authentication) {
990: error("Keyboard-interactive authentication is disabled"
991: " to avoid man-in-the-middle attacks.");
992: options.kbd_interactive_authentication = 0;
993: options.challenge_response_authentication = 0;
1.210 dtucker 994: cancelled_forwarding = 1;
1.144 djm 995: }
996: if (options.challenge_response_authentication) {
997: error("Challenge/response authentication is disabled"
998: " to avoid man-in-the-middle attacks.");
999: options.challenge_response_authentication = 0;
1.210 dtucker 1000: cancelled_forwarding = 1;
1.38 markus 1001: }
1002: if (options.forward_agent) {
1.108 markus 1003: error("Agent forwarding is disabled to avoid "
1004: "man-in-the-middle attacks.");
1.38 markus 1005: options.forward_agent = 0;
1.210 dtucker 1006: cancelled_forwarding = 1;
1.83 markus 1007: }
1008: if (options.forward_x11) {
1.108 markus 1009: error("X11 forwarding is disabled to avoid "
1010: "man-in-the-middle attacks.");
1.83 markus 1011: options.forward_x11 = 0;
1.210 dtucker 1012: cancelled_forwarding = 1;
1.83 markus 1013: }
1.108 markus 1014: if (options.num_local_forwards > 0 ||
1015: options.num_remote_forwards > 0) {
1016: error("Port forwarding is disabled to avoid "
1017: "man-in-the-middle attacks.");
1018: options.num_local_forwards =
1.118 deraadt 1019: options.num_remote_forwards = 0;
1.210 dtucker 1020: cancelled_forwarding = 1;
1.194 stevesk 1021: }
1022: if (options.tun_open != SSH_TUNMODE_NO) {
1023: error("Tunnel forwarding is disabled to avoid "
1024: "man-in-the-middle attacks.");
1025: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1026: cancelled_forwarding = 1;
1.38 markus 1027: }
1.210 dtucker 1028: if (options.exit_on_forward_failure && cancelled_forwarding)
1029: fatal("Error: forwarding disabled due to host key "
1030: "check failure");
1031:
1.40 markus 1032: /*
1033: * XXX Should permit the user to change to use the new id.
1034: * This could be done by converting the host key to an
1035: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1036: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1037: * accept the authentication.
1038: */
1.38 markus 1039: break;
1.132 markus 1040: case HOST_FOUND:
1041: fatal("internal error");
1042: break;
1.88 markus 1043: }
1044:
1045: if (options.check_host_ip && host_status != HOST_CHANGED &&
1046: ip_status == HOST_CHANGED) {
1.119 markus 1047: snprintf(msg, sizeof(msg),
1048: "Warning: the %s host key for '%.200s' "
1049: "differs from the key for the IP address '%.128s'"
1.229 djm 1050: "\nOffending key for IP in %s:%lu",
1051: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1052: if (host_status == HOST_OK) {
1053: len = strlen(msg);
1054: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1055: "\nMatching host key in %s:%lu",
1056: host_found->file, host_found->line);
1.119 markus 1057: }
1.285 djm 1058: if (options.strict_host_key_checking ==
1059: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1060: strlcat(msg, "\nAre you sure you want "
1061: "to continue connecting (yes/no)? ", sizeof(msg));
1.312 dtucker 1062: if (!confirm(msg, NULL))
1.108 markus 1063: goto fail;
1.285 djm 1064: } else if (options.strict_host_key_checking !=
1065: SSH_STRICT_HOSTKEY_OFF) {
1066: logit("%s", msg);
1067: error("Exiting, you have requested strict checking.");
1068: goto fail;
1.119 markus 1069: } else {
1.143 djm 1070: logit("%s", msg);
1.88 markus 1071: }
1.257 djm 1072: }
1073:
1074: if (!hostkey_trusted && options.update_hostkeys) {
1075: debug("%s: hostkey not known or explicitly trusted: "
1076: "disabling UpdateHostkeys", __func__);
1077: options.update_hostkeys = 0;
1.38 markus 1078: }
1.82 provos 1079:
1.238 djm 1080: free(ip);
1081: free(host);
1.229 djm 1082: if (host_hostkeys != NULL)
1083: free_hostkeys(host_hostkeys);
1084: if (ip_hostkeys != NULL)
1085: free_hostkeys(ip_hostkeys);
1.333 djm 1086: if (cert_fallbackp != NULL)
1087: *cert_fallbackp = cert_fallback;
1.108 markus 1088: return 0;
1089:
1090: fail:
1.333 djm 1091: if (cert_fallbackp != NULL && want_cert &&
1092: host_status != HOST_REVOKED) {
1.219 djm 1093: /*
1094: * No matching certificate. Downgrade cert to raw key and
1095: * search normally.
1096: */
1097: debug("No matching CA found. Retry with plain key");
1.280 markus 1098: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1099: fatal("%s: sshkey_from_private: %s",
1100: __func__, ssh_err(r));
1101: if ((r = sshkey_drop_cert(raw_key)) != 0)
1102: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1103: host_key = raw_key;
1.333 djm 1104: cert_fallback = 1;
1.219 djm 1105: goto retry;
1106: }
1.293 dtucker 1107: sshkey_free(raw_key);
1.238 djm 1108: free(ip);
1109: free(host);
1.229 djm 1110: if (host_hostkeys != NULL)
1111: free_hostkeys(host_hostkeys);
1112: if (ip_hostkeys != NULL)
1113: free_hostkeys(ip_hostkeys);
1.108 markus 1114: return -1;
1115: }
1116:
1.333 djm 1117: /*
1118: * returns 0 if key verifies or -1 if key does NOT verify.
1119: *
1120: * If the host key was a certificate that was downgraded to a plain key in
1121: * the process of matching, then cert_fallbackp will be non-zero.
1122: */
1.108 markus 1123: int
1.333 djm 1124: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key,
1125: int *cert_fallbackp)
1.108 markus 1126: {
1.267 djm 1127: u_int i;
1.333 djm 1128: int r = -1, flags = 0, cert_fallback = 0;
1.267 djm 1129: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1130: struct sshkey *plain = NULL;
1.229 djm 1131:
1.333 djm 1132: if (cert_fallbackp != NULL)
1133: *cert_fallbackp = 0;
1134:
1.252 djm 1135: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1136: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1137: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1138: r = -1;
1139: goto out;
1140: }
1141:
1.267 djm 1142: if (sshkey_is_cert(host_key)) {
1143: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1144: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1145: error("%s: fingerprint CA key: %s",
1146: __func__, ssh_err(r));
1147: r = -1;
1148: goto out;
1149: }
1150: sshkey_format_cert_validity(host_key->cert,
1151: valid, sizeof(valid));
1152: debug("Server host certificate: %s %s, serial %llu "
1153: "ID \"%s\" CA %s %s valid %s",
1154: sshkey_ssh_name(host_key), fp,
1.269 djm 1155: (unsigned long long)host_key->cert->serial,
1156: host_key->cert->key_id,
1.267 djm 1157: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1158: valid);
1159: for (i = 0; i < host_key->cert->nprincipals; i++) {
1160: debug2("Server host certificate hostname: %s",
1161: host_key->cert->principals[i]);
1162: }
1163: } else {
1.276 djm 1164: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1165: }
1.252 djm 1166:
1167: if (sshkey_equal(previous_host_key, host_key)) {
1168: debug2("%s: server host key %s %s matches cached key",
1169: __func__, sshkey_type(host_key), fp);
1170: r = 0;
1171: goto out;
1172: }
1173:
1174: /* Check in RevokedHostKeys file if specified */
1175: if (options.revoked_host_keys != NULL) {
1176: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1177: switch (r) {
1178: case 0:
1179: break; /* not revoked */
1180: case SSH_ERR_KEY_REVOKED:
1181: error("Host key %s %s revoked by file %s",
1182: sshkey_type(host_key), fp,
1183: options.revoked_host_keys);
1184: r = -1;
1185: goto out;
1186: default:
1187: error("Error checking host key %s %s in "
1188: "revoked keys file %s: %s", sshkey_type(host_key),
1189: fp, options.revoked_host_keys, ssh_err(r));
1190: r = -1;
1191: goto out;
1192: }
1.250 djm 1193: }
1194:
1.247 djm 1195: if (options.verify_host_key_dns) {
1196: /*
1197: * XXX certs are not yet supported for DNS, so downgrade
1198: * them and try the plain key.
1199: */
1.252 djm 1200: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1201: goto out;
1202: if (sshkey_is_cert(plain))
1203: sshkey_drop_cert(plain);
1.247 djm 1204: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1205: if (flags & DNS_VERIFY_FOUND) {
1206: if (options.verify_host_key_dns == 1 &&
1207: flags & DNS_VERIFY_MATCH &&
1208: flags & DNS_VERIFY_SECURE) {
1.250 djm 1209: r = 0;
1.252 djm 1210: goto out;
1.247 djm 1211: }
1212: if (flags & DNS_VERIFY_MATCH) {
1213: matching_host_key_dns = 1;
1214: } else {
1.287 djm 1215: warn_changed_key(plain);
1216: error("Update the SSHFP RR in DNS "
1217: "with the new host key to get rid "
1218: "of this message.");
1.247 djm 1219: }
1.153 jakob 1220: }
1.140 jakob 1221: }
1222: }
1.250 djm 1223: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1224: options.user_hostfiles, options.num_user_hostfiles,
1.333 djm 1225: options.system_hostfiles, options.num_system_hostfiles,
1226: &cert_fallback);
1.250 djm 1227:
1.252 djm 1228: out:
1229: sshkey_free(plain);
1230: free(fp);
1.267 djm 1231: free(cafp);
1.333 djm 1232: if (r == 0) {
1233: if (host_key != NULL) {
1234: sshkey_free(previous_host_key);
1235: r = sshkey_from_private(host_key, &previous_host_key);
1236: }
1237: if (r == 0 && cert_fallbackp != NULL)
1238: *cert_fallbackp = cert_fallback;
1.250 djm 1239: }
1240:
1241: return r;
1.51 markus 1242: }
1.70 markus 1243:
1.51 markus 1244: /*
1245: * Starts a dialog with the server, and authenticates the current user on the
1246: * server. This does not need any extra privileges. The basic connection
1247: * to the server must already have been established before this is called.
1248: * If login fails, this function prints an error and never returns.
1249: * This function does not require super-user privileges.
1250: */
1251: void
1.309 djm 1252: ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost,
1.229 djm 1253: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1254: {
1.241 djm 1255: char *host;
1.70 markus 1256: char *server_user, *local_user;
1.329 djm 1257: int r;
1.70 markus 1258:
1259: local_user = xstrdup(pw->pw_name);
1260: server_user = options.user ? options.user : local_user;
1.51 markus 1261:
1262: /* Convert the user-supplied hostname into all lowercase. */
1263: host = xstrdup(orighost);
1.241 djm 1264: lowercase(host);
1.51 markus 1265:
1266: /* Exchange protocol version identification strings with the server. */
1.329 djm 1267: if ((r = kex_exchange_identification(ssh, timeout_ms, NULL)) != 0)
1268: sshpkt_fatal(ssh, r, "banner exchange");
1.51 markus 1269:
1270: /* Put the connection into non-blocking mode. */
1.309 djm 1271: ssh_packet_set_nonblocking(ssh);
1.51 markus 1272:
1273: /* key exchange */
1274: /* authenticate user */
1.261 dtucker 1275: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.309 djm 1276: ssh_kex2(ssh, host, hostaddr, port);
1277: ssh_userauth2(ssh, local_user, server_user, host, sensitive);
1.238 djm 1278: free(local_user);
1.315 dtucker 1279: free(host);
1.132 markus 1280: }
1281:
1282: /* print all known host keys for a given host, but skip keys of given type */
1283: static int
1.279 markus 1284: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1285: {
1.242 djm 1286: int type[] = {
1287: KEY_RSA,
1288: KEY_DSA,
1289: KEY_ECDSA,
1290: KEY_ED25519,
1.297 markus 1291: KEY_XMSS,
1.242 djm 1292: -1
1293: };
1.229 djm 1294: int i, ret = 0;
1295: char *fp, *ra;
1296: const struct hostkey_entry *found;
1.132 markus 1297:
1298: for (i = 0; type[i] != -1; i++) {
1299: if (type[i] == key->type)
1300: continue;
1.335 ! djm 1301: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i],
! 1302: -1, &found))
1.132 markus 1303: continue;
1.259 djm 1304: fp = sshkey_fingerprint(found->key,
1.254 djm 1305: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1306: ra = sshkey_fingerprint(found->key,
1.254 djm 1307: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1308: if (fp == NULL || ra == NULL)
1309: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1310: logit("WARNING: %s key found for host %s\n"
1311: "in %s:%lu\n"
1312: "%s key fingerprint %s.",
1.300 markus 1313: sshkey_type(found->key),
1.229 djm 1314: found->host, found->file, found->line,
1.300 markus 1315: sshkey_type(found->key), fp);
1.229 djm 1316: if (options.visual_host_key)
1317: logit("%s", ra);
1.238 djm 1318: free(ra);
1319: free(fp);
1.229 djm 1320: ret = 1;
1.132 markus 1321: }
1.229 djm 1322: return ret;
1.150 jakob 1323: }
1324:
1325: static void
1.279 markus 1326: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1327: {
1328: char *fp;
1329:
1.259 djm 1330: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1331: SSH_FP_DEFAULT);
1.259 djm 1332: if (fp == NULL)
1333: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1334:
1335: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1336: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1337: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1338: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1339: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1340: error("It is also possible that a host key has just been changed.");
1.150 jakob 1341: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.300 markus 1342: sshkey_type(host_key), fp);
1.150 jakob 1343: error("Please contact your system administrator.");
1344:
1.238 djm 1345: free(fp);
1.171 reyk 1346: }
1347:
1348: /*
1349: * Execute a local command
1350: */
1351: int
1352: ssh_local_cmd(const char *args)
1353: {
1354: char *shell;
1355: pid_t pid;
1356: int status;
1.231 djm 1357: void (*osighand)(int);
1.171 reyk 1358:
1359: if (!options.permit_local_command ||
1360: args == NULL || !*args)
1361: return (1);
1362:
1.226 djm 1363: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1364: shell = _PATH_BSHELL;
1365:
1.327 dtucker 1366: osighand = ssh_signal(SIGCHLD, SIG_DFL);
1.171 reyk 1367: pid = fork();
1368: if (pid == 0) {
1.327 dtucker 1369: ssh_signal(SIGPIPE, SIG_DFL);
1.171 reyk 1370: debug3("Executing %s -c \"%s\"", shell, args);
1371: execl(shell, shell, "-c", args, (char *)NULL);
1372: error("Couldn't execute %s -c \"%s\": %s",
1373: shell, args, strerror(errno));
1374: _exit(1);
1375: } else if (pid == -1)
1376: fatal("fork failed: %.100s", strerror(errno));
1377: while (waitpid(pid, &status, 0) == -1)
1378: if (errno != EINTR)
1379: fatal("Couldn't wait for child: %s", strerror(errno));
1.327 dtucker 1380: ssh_signal(SIGCHLD, osighand);
1.171 reyk 1381:
1382: if (!WIFEXITED(status))
1383: return (1);
1384:
1385: return (WEXITSTATUS(status));
1.266 jcs 1386: }
1387:
1388: void
1.328 djm 1389: maybe_add_key_to_agent(const char *authfile, struct sshkey *private,
1390: const char *comment, const char *passphrase)
1.266 jcs 1391: {
1392: int auth_sock = -1, r;
1.321 djm 1393: const char *skprovider = NULL;
1.266 jcs 1394:
1395: if (options.add_keys_to_agent == 0)
1396: return;
1397:
1398: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1399: debug3("no authentication agent, not adding key");
1400: return;
1401: }
1402:
1403: if (options.add_keys_to_agent == 2 &&
1404: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1405: debug3("user denied adding this key");
1.273 dtucker 1406: close(auth_sock);
1.266 jcs 1407: return;
1408: }
1.322 markus 1409: if (sshkey_is_sk(private))
1.321 djm 1410: skprovider = options.sk_provider;
1.328 djm 1411: if ((r = ssh_add_identity_constrained(auth_sock, private,
1.331 djm 1412: comment == NULL ? authfile : comment,
1413: options.add_keys_to_agent_lifespan,
1.321 djm 1414: (options.add_keys_to_agent == 3), 0, skprovider)) == 0)
1.266 jcs 1415: debug("identity added to agent: %s", authfile);
1416: else
1417: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1418: close(auth_sock);
1.1 deraadt 1419: }
![[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