Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.345
1.345 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.344 2020/11/22 22:37:11 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>
1.345 ! djm 29: #include <limits.h>
1.172 stevesk 30: #include <paths.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>
1.323 deraadt 35: #include <stdarg.h>
1.193 stevesk 36: #include <string.h>
1.192 stevesk 37: #include <unistd.h>
1.295 djm 38: #include <ifaddrs.h>
1.71 markus 39:
1.199 deraadt 40: #include "xmalloc.h"
1.91 markus 41: #include "ssh.h"
1.299 markus 42: #include "sshbuf.h"
1.1 deraadt 43: #include "packet.h"
1.21 markus 44: #include "compat.h"
1.300 markus 45: #include "sshkey.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"
1.309 djm 59: #include "kex.h"
1.310 djm 60:
1.279 markus 61: struct sshkey *previous_host_key = NULL;
1.59 markus 62:
1.169 stevesk 63: static int matching_host_key_dns = 0;
1.145 jakob 64:
1.227 djm 65: static pid_t proxy_command_pid = 0;
66:
1.124 markus 67: /* import */
1.307 djm 68: extern int debug_flag;
1.43 markus 69: extern Options options;
1.50 markus 70: extern char *__progname;
1.91 markus 71:
1.279 markus 72: static int show_other_keys(struct hostkeys *, struct sshkey *);
73: static void warn_changed_key(struct sshkey *);
1.132 markus 74:
1.239 djm 75: /* Expand a proxy command */
76: static char *
77: expand_proxy_command(const char *proxy_command, const char *user,
1.325 naddy 78: const char *host, const char *host_arg, int port)
1.239 djm 79: {
80: char *tmp, *ret, strport[NI_MAXSERV];
1.330 dtucker 81: const char *keyalias = options.host_key_alias ?
82: options.host_key_alias : host_arg;
1.239 djm 83:
1.241 djm 84: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 85: xasprintf(&tmp, "exec %s", proxy_command);
1.318 djm 86: ret = percent_expand(tmp,
87: "h", host,
1.330 dtucker 88: "k", keyalias,
1.318 djm 89: "n", host_arg,
90: "p", strport,
91: "r", options.user,
92: (char *)NULL);
1.239 djm 93: free(tmp);
94: return ret;
95: }
96:
97: /*
98: * Connect to the given ssh server using a proxy command that passes a
99: * a connected fd back to us.
100: */
101: static int
1.318 djm 102: ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host,
103: const char *host_arg, u_short port, const char *proxy_command)
1.239 djm 104: {
105: char *command_string;
106: int sp[2], sock;
107: pid_t pid;
108: char *shell;
109:
110: if ((shell = getenv("SHELL")) == NULL)
111: shell = _PATH_BSHELL;
112:
1.317 deraadt 113: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) == -1)
1.239 djm 114: fatal("Could not create socketpair to communicate with "
115: "proxy dialer: %.100s", strerror(errno));
116:
117: command_string = expand_proxy_command(proxy_command, options.user,
1.325 naddy 118: host, host_arg, port);
1.239 djm 119: debug("Executing proxy dialer command: %.500s", command_string);
120:
121: /* Fork and execute the proxy command. */
122: if ((pid = fork()) == 0) {
123: char *argv[10];
124:
125: close(sp[1]);
126: /* Redirect stdin and stdout. */
127: if (sp[0] != 0) {
1.317 deraadt 128: if (dup2(sp[0], 0) == -1)
1.239 djm 129: perror("dup2 stdin");
130: }
131: if (sp[0] != 1) {
1.317 deraadt 132: if (dup2(sp[0], 1) == -1)
1.239 djm 133: perror("dup2 stdout");
134: }
135: if (sp[0] >= 2)
136: close(sp[0]);
137:
138: /*
1.307 djm 139: * Stderr is left for non-ControlPersist connections is so
140: * error messages may be printed on the user's terminal.
1.239 djm 141: */
1.308 dtucker 142: if (!debug_flag && options.control_path != NULL &&
1.334 djm 143: options.control_persist && stdfd_devnull(0, 0, 1) == -1)
1.341 djm 144: error_f("stdfd_devnull failed");
1.307 djm 145:
1.239 djm 146: argv[0] = shell;
147: argv[1] = "-c";
148: argv[2] = command_string;
149: argv[3] = NULL;
150:
151: /*
152: * Execute the proxy command.
153: * Note that we gave up any extra privileges above.
154: */
155: execv(argv[0], argv);
156: perror(argv[0]);
157: exit(1);
158: }
159: /* Parent. */
1.317 deraadt 160: if (pid == -1)
1.239 djm 161: fatal("fork failed: %.100s", strerror(errno));
162: close(sp[0]);
163: free(command_string);
164:
165: if ((sock = mm_receive_fd(sp[1])) == -1)
166: fatal("proxy dialer did not pass back a connection");
1.271 markus 167: close(sp[1]);
1.239 djm 168:
169: while (waitpid(pid, NULL, 0) == -1)
170: if (errno != EINTR)
171: fatal("Couldn't wait for child: %s", strerror(errno));
172:
173: /* Set the connection file descriptors. */
1.286 djm 174: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
175: return -1; /* ssh_packet_set_connection logs error */
1.239 djm 176:
177: return 0;
178: }
179:
1.39 deraadt 180: /*
181: * Connect to the given ssh server using a proxy command.
182: */
1.109 itojun 183: static int
1.318 djm 184: ssh_proxy_connect(struct ssh *ssh, const char *host, const char *host_arg,
185: u_short port, const char *proxy_command)
1.1 deraadt 186: {
1.239 djm 187: char *command_string;
1.38 markus 188: int pin[2], pout[2];
1.69 deraadt 189: pid_t pid;
1.239 djm 190: char *shell;
1.237 markus 191:
1.226 djm 192: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 193: shell = _PATH_BSHELL;
1.38 markus 194:
195: /* Create pipes for communicating with the proxy. */
1.317 deraadt 196: if (pipe(pin) == -1 || pipe(pout) == -1)
1.38 markus 197: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 198: strerror(errno));
1.38 markus 199:
1.239 djm 200: command_string = expand_proxy_command(proxy_command, options.user,
1.325 naddy 201: host, host_arg, port);
1.38 markus 202: debug("Executing proxy command: %.500s", command_string);
203:
204: /* Fork and execute the proxy command. */
205: if ((pid = fork()) == 0) {
206: char *argv[10];
207:
208: /* Redirect stdin and stdout. */
209: close(pin[1]);
210: if (pin[0] != 0) {
1.317 deraadt 211: if (dup2(pin[0], 0) == -1)
1.38 markus 212: perror("dup2 stdin");
213: close(pin[0]);
214: }
215: close(pout[0]);
1.317 deraadt 216: if (dup2(pout[1], 1) == -1)
1.38 markus 217: perror("dup2 stdout");
218: /* Cannot be 1 because pin allocated two descriptors. */
219: close(pout[1]);
220:
1.307 djm 221: /*
222: * Stderr is left for non-ControlPersist connections is so
223: * error messages may be printed on the user's terminal.
224: */
1.308 dtucker 225: if (!debug_flag && options.control_path != NULL &&
1.334 djm 226: options.control_persist && stdfd_devnull(0, 0, 1) == -1)
1.341 djm 227: error_f("stdfd_devnull failed");
1.307 djm 228:
1.201 djm 229: argv[0] = shell;
1.38 markus 230: argv[1] = "-c";
231: argv[2] = command_string;
232: argv[3] = NULL;
233:
234: /* Execute the proxy command. Note that we gave up any
235: extra privileges above. */
1.327 dtucker 236: ssh_signal(SIGPIPE, SIG_DFL);
1.89 markus 237: execv(argv[0], argv);
238: perror(argv[0]);
1.38 markus 239: exit(1);
240: }
241: /* Parent. */
1.317 deraadt 242: if (pid == -1)
1.38 markus 243: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 244: else
245: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 246:
247: /* Close child side of the descriptors. */
248: close(pin[0]);
249: close(pout[1]);
250:
251: /* Free the command name. */
1.238 djm 252: free(command_string);
1.38 markus 253:
254: /* Set the connection file descriptors. */
1.286 djm 255: if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
256: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 257:
1.110 markus 258: return 0;
1.227 djm 259: }
260:
261: void
262: ssh_kill_proxy_command(void)
263: {
264: /*
265: * Send SIGHUP to proxy command if used. We don't wait() in
266: * case it hangs and instead rely on init to reap the child
267: */
268: if (proxy_command_pid > 1)
1.228 djm 269: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 270: }
271:
1.39 deraadt 272: /*
1.295 djm 273: * Search a interface address list (returned from getifaddrs(3)) for an
1.298 djm 274: * address that matches the desired address family on the specified interface.
1.295 djm 275: * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure.
276: */
277: static int
278: check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs,
279: struct sockaddr_storage *resultp, socklen_t *rlenp)
280: {
281: struct sockaddr_in6 *sa6;
282: struct sockaddr_in *sa;
283: struct in6_addr *v6addr;
284: const struct ifaddrs *ifa;
285: int allow_local;
286:
287: /*
288: * Prefer addresses that are not loopback or linklocal, but use them
289: * if nothing else matches.
290: */
291: for (allow_local = 0; allow_local < 2; allow_local++) {
292: for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
293: if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL ||
294: (ifa->ifa_flags & IFF_UP) == 0 ||
295: ifa->ifa_addr->sa_family != af ||
296: strcmp(ifa->ifa_name, options.bind_interface) != 0)
297: continue;
298: switch (ifa->ifa_addr->sa_family) {
299: case AF_INET:
300: sa = (struct sockaddr_in *)ifa->ifa_addr;
301: if (!allow_local && sa->sin_addr.s_addr ==
302: htonl(INADDR_LOOPBACK))
303: continue;
304: if (*rlenp < sizeof(struct sockaddr_in)) {
1.341 djm 305: error_f("v4 addr doesn't fit");
1.295 djm 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)) {
1.341 djm 319: error_f("v6 addr doesn't fit");
1.295 djm 320: return -1;
321: }
322: *rlenp = sizeof(struct sockaddr_in6);
323: memcpy(resultp, sa6, *rlenp);
324: return 0;
325: }
326: }
327: }
328: return -1;
329: }
330:
331: /*
1.303 dtucker 332: * Creates a socket for use as the ssh connection.
1.39 deraadt 333: */
1.109 itojun 334: static int
1.302 dtucker 335: ssh_create_socket(struct addrinfo *ai)
1.1 deraadt 336: {
1.301 dtucker 337: int sock, r;
1.295 djm 338: struct sockaddr_storage bindaddr;
339: socklen_t bindaddrlen = 0;
1.246 djm 340: struct addrinfo hints, *res = NULL;
1.295 djm 341: struct ifaddrs *ifaddrs = NULL;
342: char ntop[NI_MAXHOST];
1.1 deraadt 343:
1.217 dtucker 344: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.317 deraadt 345: if (sock == -1) {
1.240 djm 346: error("socket: %s", strerror(errno));
1.216 dtucker 347: return -1;
348: }
349: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.345 ! djm 350:
! 351: /* Use interactive QOS (if specified) until authentication completed */
! 352: if (options.ip_qos_interactive != INT_MAX)
! 353: set_sock_tos(sock, options.ip_qos_interactive);
1.105 markus 354:
355: /* Bind the socket to an alternative local IP address */
1.302 dtucker 356: if (options.bind_address == NULL && options.bind_interface == NULL)
1.105 markus 357: return sock;
358:
1.295 djm 359: if (options.bind_address != NULL) {
1.246 djm 360: memset(&hints, 0, sizeof(hints));
361: hints.ai_family = ai->ai_family;
362: hints.ai_socktype = ai->ai_socktype;
363: hints.ai_protocol = ai->ai_protocol;
364: hints.ai_flags = AI_PASSIVE;
1.295 djm 365: if ((r = getaddrinfo(options.bind_address, NULL,
366: &hints, &res)) != 0) {
1.246 djm 367: error("getaddrinfo: %s: %s", options.bind_address,
1.295 djm 368: ssh_gai_strerror(r));
369: goto fail;
370: }
1.296 dtucker 371: if (res == NULL) {
1.295 djm 372: error("getaddrinfo: no addrs");
373: goto fail;
374: }
375: memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
376: bindaddrlen = res->ai_addrlen;
377: } else if (options.bind_interface != NULL) {
378: if ((r = getifaddrs(&ifaddrs)) != 0) {
379: error("getifaddrs: %s: %s", options.bind_interface,
380: strerror(errno));
381: goto fail;
382: }
383: bindaddrlen = sizeof(bindaddr);
384: if (check_ifaddrs(options.bind_interface, ai->ai_family,
385: ifaddrs, &bindaddr, &bindaddrlen) != 0) {
386: logit("getifaddrs: %s: no suitable addresses",
387: options.bind_interface);
388: goto fail;
1.246 djm 389: }
1.105 markus 390: }
1.295 djm 391: if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
392: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
1.341 djm 393: error_f("getnameinfo failed: %s", ssh_gai_strerror(r));
1.295 djm 394: goto fail;
395: }
1.301 dtucker 396: if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
1.295 djm 397: error("bind %s: %s", ntop, strerror(errno));
398: goto fail;
1.38 markus 399: }
1.341 djm 400: debug_f("bound to %s", ntop);
1.295 djm 401: /* success */
402: goto out;
403: fail:
404: close(sock);
405: sock = -1;
406: out:
1.246 djm 407: if (res != NULL)
408: freeaddrinfo(res);
1.295 djm 409: if (ifaddrs != NULL)
410: freeifaddrs(ifaddrs);
1.38 markus 411: return sock;
1.1 deraadt 412: }
413:
1.282 djm 414: /*
1.49 markus 415: * Opens a TCP/IP connection to the remote server on the given host.
416: * The address of the remote host will be returned in hostaddr.
1.302 dtucker 417: * If port is 0, the default port will be used.
1.39 deraadt 418: * Connection_attempts specifies the maximum number of tries (one per
419: * second). If proxy_command is non-NULL, it specifies the command (with %h
420: * and %p substituted for host and port, respectively) to use to contact
421: * the daemon.
422: */
1.241 djm 423: static int
1.286 djm 424: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.340 kn 425: struct sockaddr_storage *hostaddr, u_short port, int connection_attempts,
426: int *timeout_ms, int want_keepalive)
1.1 deraadt 427: {
1.313 dtucker 428: int on = 1, saved_timeout_ms = *timeout_ms;
1.290 djm 429: int oerrno, sock = -1, attempt;
1.90 markus 430: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 431: struct addrinfo *ai;
1.38 markus 432:
1.341 djm 433: debug3_f("entering");
1.268 djm 434: memset(ntop, 0, sizeof(ntop));
435: memset(strport, 0, sizeof(strport));
1.38 markus 436:
1.181 markus 437: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 438: if (attempt > 0) {
439: /* Sleep a moment before retrying. */
440: sleep(1);
1.38 markus 441: debug("Trying again...");
1.200 markus 442: }
1.181 markus 443: /*
444: * Loop through addresses for this host, and try each one in
445: * sequence until the connection succeeds.
446: */
1.49 markus 447: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 448: if (ai->ai_family != AF_INET &&
1.290 djm 449: ai->ai_family != AF_INET6) {
450: errno = EAFNOSUPPORT;
1.49 markus 451: continue;
1.290 djm 452: }
1.49 markus 453: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
454: ntop, sizeof(ntop), strport, sizeof(strport),
455: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.290 djm 456: oerrno = errno;
1.341 djm 457: error_f("getnameinfo failed");
1.290 djm 458: errno = oerrno;
1.49 markus 459: continue;
460: }
461: debug("Connecting to %.200s [%.100s] port %s.",
462: host, ntop, strport);
463:
464: /* Create a socket for connecting. */
1.302 dtucker 465: sock = ssh_create_socket(ai);
1.292 stsp 466: if (sock < 0) {
1.110 markus 467: /* Any error is already output */
1.290 djm 468: errno = 0;
1.49 markus 469: continue;
1.292 stsp 470: }
1.49 markus 471:
1.313 dtucker 472: *timeout_ms = saved_timeout_ms;
1.141 djm 473: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 474: timeout_ms) >= 0) {
1.49 markus 475: /* Successful connection. */
1.102 markus 476: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 477: break;
1.49 markus 478: } else {
1.290 djm 479: oerrno = errno;
1.131 itojun 480: debug("connect to address %s port %s: %s",
481: ntop, strport, strerror(errno));
1.38 markus 482: close(sock);
1.181 markus 483: sock = -1;
1.290 djm 484: errno = oerrno;
1.38 markus 485: }
486: }
1.181 markus 487: if (sock != -1)
1.49 markus 488: break; /* Successful connection. */
1.38 markus 489: }
1.49 markus 490:
1.38 markus 491: /* Return failure if we didn't get a successful connection. */
1.181 markus 492: if (sock == -1) {
1.159 markus 493: error("ssh: connect to host %s port %s: %s",
1.290 djm 494: host, strport, errno == 0 ? "failure" : strerror(errno));
495: return -1;
1.130 itojun 496: }
1.38 markus 497:
498: debug("Connection established.");
1.90 markus 499:
1.155 markus 500: /* Set SO_KEEPALIVE if requested. */
1.202 djm 501: if (want_keepalive &&
1.90 markus 502: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1.317 deraadt 503: sizeof(on)) == -1)
1.90 markus 504: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 505:
506: /* Set the connection. */
1.286 djm 507: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
508: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 509:
1.319 djm 510: return 0;
1.59 markus 511: }
512:
1.241 djm 513: int
1.318 djm 514: ssh_connect(struct ssh *ssh, const char *host, const char *host_arg,
515: struct addrinfo *addrs, struct sockaddr_storage *hostaddr, u_short port,
1.340 kn 516: int connection_attempts, int *timeout_ms, int want_keepalive)
1.241 djm 517: {
1.314 markus 518: int in, out;
519:
1.241 djm 520: if (options.proxy_command == NULL) {
1.286 djm 521: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
1.340 kn 522: connection_attempts, timeout_ms, want_keepalive);
1.241 djm 523: } else if (strcmp(options.proxy_command, "-") == 0) {
1.317 deraadt 524: if ((in = dup(STDIN_FILENO)) == -1 ||
525: (out = dup(STDOUT_FILENO)) == -1) {
1.314 markus 526: if (in >= 0)
527: close(in);
1.341 djm 528: error_f("dup() in/out failed");
1.314 markus 529: return -1; /* ssh_packet_set_connection logs error */
530: }
531: if ((ssh_packet_set_connection(ssh, in, out)) == NULL)
1.286 djm 532: return -1; /* ssh_packet_set_connection logs error */
533: return 0;
1.241 djm 534: } else if (options.proxy_use_fdpass) {
1.318 djm 535: return ssh_proxy_fdpass_connect(ssh, host, host_arg, port,
1.241 djm 536: options.proxy_command);
537: }
1.318 djm 538: return ssh_proxy_connect(ssh, host, host_arg, port,
539: options.proxy_command);
1.241 djm 540: }
541:
1.96 markus 542: /* defaults to 'no' */
1.109 itojun 543: static int
1.312 dtucker 544: confirm(const char *prompt, const char *fingerprint)
1.1 deraadt 545: {
1.119 markus 546: const char *msg, *again = "Please type 'yes' or 'no': ";
1.312 dtucker 547: const char *again_fp = "Please type 'yes', 'no' or the fingerprint: ";
1.326 dtucker 548: char *p, *cp;
1.119 markus 549: int ret = -1;
1.96 markus 550:
551: if (options.batch_mode)
552: return 0;
1.312 dtucker 553: for (msg = prompt;;msg = fingerprint ? again_fp : again) {
1.326 dtucker 554: cp = p = read_passphrase(msg, RP_ECHO);
1.289 djm 555: if (p == NULL)
556: return 0;
1.326 dtucker 557: p += strspn(p, " \t"); /* skip leading whitespace */
558: p[strcspn(p, " \t\n")] = '\0'; /* remove trailing whitespace */
1.289 djm 559: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 560: ret = 0;
1.312 dtucker 561: else if (strcasecmp(p, "yes") == 0 || (fingerprint != NULL &&
1.332 djm 562: strcmp(p, fingerprint) == 0))
1.119 markus 563: ret = 1;
1.326 dtucker 564: free(cp);
1.119 markus 565: if (ret != -1)
566: return ret;
1.1 deraadt 567: }
568: }
569:
1.219 djm 570: static int
1.305 djm 571: check_host_cert(const char *host, const struct sshkey *key)
1.219 djm 572: {
573: const char *reason;
1.305 djm 574: int r;
1.219 djm 575:
1.305 djm 576: if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) {
1.219 djm 577: error("%s", reason);
578: return 0;
579: }
1.305 djm 580: if (sshbuf_len(key->cert->critical) != 0) {
1.223 djm 581: error("Certificate for %s contains unsupported "
582: "critical options(s)", host);
1.219 djm 583: return 0;
584: }
1.305 djm 585: if ((r = sshkey_check_cert_sigtype(key,
586: options.ca_sign_algorithms)) != 0) {
1.341 djm 587: logit_fr(r, "certificate signature algorithm %s",
1.305 djm 588: (key->cert == NULL || key->cert->signature_type == NULL) ?
1.341 djm 589: "(null)" : key->cert->signature_type);
1.305 djm 590: return 0;
591: }
1.336 djm 592: /* Do not attempt hostkey update if a certificate was successful */
593: if (options.update_hostkeys != 0) {
594: options.update_hostkeys = 0;
1.341 djm 595: debug3_f("certificate host key in use; disabling UpdateHostkeys");
1.336 djm 596: }
1.219 djm 597: return 1;
598: }
599:
1.229 djm 600: static int
601: sockaddr_is_local(struct sockaddr *hostaddr)
602: {
603: switch (hostaddr->sa_family) {
604: case AF_INET:
605: return (ntohl(((struct sockaddr_in *)hostaddr)->
606: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
607: case AF_INET6:
608: return IN6_IS_ADDR_LOOPBACK(
609: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
610: default:
611: return 0;
612: }
613: }
614:
615: /*
616: * Prepare the hostname and ip address strings that are used to lookup
617: * host keys in known_hosts files. These may have a port number appended.
618: */
619: void
620: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
621: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
622: {
623: char ntop[NI_MAXHOST];
624:
625: /*
626: * We don't have the remote ip-address for connections
627: * using a proxy command
628: */
629: if (hostfile_ipaddr != NULL) {
630: if (options.proxy_command == NULL) {
631: if (getnameinfo(hostaddr, hostaddr->sa_len,
632: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.341 djm 633: fatal_f("getnameinfo failed");
1.229 djm 634: *hostfile_ipaddr = put_host_port(ntop, port);
635: } else {
636: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
637: "command>");
638: }
639: }
640:
641: /*
642: * Allow the user to record the key under a different name or
643: * differentiate a non-standard port. This is useful for ssh
644: * tunneling over forwarded connections or if you run multiple
645: * sshd's on different ports on the same machine.
646: */
647: if (hostfile_hostname != NULL) {
648: if (options.host_key_alias != NULL) {
649: *hostfile_hostname = xstrdup(options.host_key_alias);
650: debug("using hostkeyalias: %s", *hostfile_hostname);
651: } else {
652: *hostfile_hostname = put_host_port(hostname, port);
653: }
654: }
655: }
656:
1.338 djm 657: /* returns non-zero if path appears in hostfiles, or 0 if not. */
658: static int
659: path_in_hostfiles(const char *path, char **hostfiles, u_int num_hostfiles)
660: {
661: u_int i;
662:
663: for (i = 0; i < num_hostfiles; i++) {
664: if (strcmp(path, hostfiles[i]) == 0)
665: return 1;
666: }
667: return 0;
668: }
669:
1.342 djm 670: struct find_by_key_ctx {
671: const char *host, *ip;
672: const struct sshkey *key;
673: char **names;
674: u_int nnames;
675: };
676:
677: /* Try to replace home directory prefix (per $HOME) with a ~/ sequence */
678: static char *
679: try_tilde_unexpand(const char *path)
680: {
681: char *home, *ret = NULL;
682: size_t l;
683:
684: if (*path != '/')
685: return xstrdup(path);
686: if ((home = getenv("HOME")) == NULL || (l = strlen(home)) == 0)
687: return xstrdup(path);
688: if (strncmp(path, home, l) != 0)
689: return xstrdup(path);
690: /*
691: * ensure we have matched on a path boundary: either the $HOME that
692: * we just compared ends with a '/' or the next character of the path
693: * must be a '/'.
694: */
695: if (home[l - 1] != '/' && path[l] != '/')
696: return xstrdup(path);
697: if (path[l] == '/')
698: l++;
699: xasprintf(&ret, "~/%s", path + l);
700: return ret;
701: }
702:
703: static int
704: hostkeys_find_by_key_cb(struct hostkey_foreach_line *l, void *_ctx)
705: {
706: struct find_by_key_ctx *ctx = (struct find_by_key_ctx *)_ctx;
707: char *path;
708:
709: /* we are looking for keys with names that *do not* match */
710: if ((l->match & HKF_MATCH_HOST) != 0)
711: return 0;
712: /* not interested in marker lines */
713: if (l->marker != MRK_NONE)
714: return 0;
715: /* we are only interested in exact key matches */
716: if (l->key == NULL || !sshkey_equal(ctx->key, l->key))
717: return 0;
718: path = try_tilde_unexpand(l->path);
719: debug_f("found matching key in %s:%lu", path, l->linenum);
720: ctx->names = xrecallocarray(ctx->names,
721: ctx->nnames, ctx->nnames + 1, sizeof(*ctx->names));
722: xasprintf(&ctx->names[ctx->nnames], "%s:%lu: %s", path, l->linenum,
723: strncmp(l->hosts, HASH_MAGIC, strlen(HASH_MAGIC)) == 0 ?
724: "[hashed name]" : l->hosts);
725: ctx->nnames++;
726: free(path);
727: return 0;
728: }
729:
730: static int
731: hostkeys_find_by_key_hostfile(const char *file, const char *which,
732: struct find_by_key_ctx *ctx)
733: {
734: int r;
735:
736: debug3_f("trying %s hostfile \"%s\"", which, file);
737: if ((r = hostkeys_foreach(file, hostkeys_find_by_key_cb, ctx,
738: ctx->host, ctx->ip, HKF_WANT_PARSE_KEY)) != 0) {
739: if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
740: debug_f("hostkeys file %s does not exist", file);
741: return 0;
742: }
743: error_fr(r, "hostkeys_foreach failed for %s", file);
744: return r;
745: }
746: return 0;
747: }
748:
749: /*
750: * Find 'key' in known hosts file(s) that do not match host/ip.
751: * Used to display also-known-as information for previously-unseen hostkeys.
752: */
753: static void
754: hostkeys_find_by_key(const char *host, const char *ip, const struct sshkey *key,
755: char **user_hostfiles, u_int num_user_hostfiles,
756: char **system_hostfiles, u_int num_system_hostfiles,
757: char ***names, u_int *nnames)
758: {
1.343 dtucker 759: struct find_by_key_ctx ctx = {0, 0, 0, 0, 0};
1.342 djm 760: u_int i;
761:
762: *names = NULL;
763: *nnames = 0;
764:
765: if (key == NULL || sshkey_is_cert(key))
766: return;
767:
768: ctx.host = host;
769: ctx.ip = ip;
770: ctx.key = key;
771:
772: for (i = 0; i < num_user_hostfiles; i++) {
773: if (hostkeys_find_by_key_hostfile(user_hostfiles[i],
774: "user", &ctx) != 0)
775: goto fail;
776: }
777: for (i = 0; i < num_system_hostfiles; i++) {
778: if (hostkeys_find_by_key_hostfile(system_hostfiles[i],
779: "system", &ctx) != 0)
780: goto fail;
781: }
782: /* success */
783: *names = ctx.names;
784: *nnames = ctx.nnames;
785: ctx.names = NULL;
786: ctx.nnames = 0;
787: return;
788: fail:
789: for (i = 0; i < ctx.nnames; i++)
790: free(ctx.names[i]);
791: free(ctx.names);
792: }
793:
794: #define MAX_OTHER_NAMES 8 /* Maximum number of names to list */
795: static char *
796: other_hostkeys_message(const char *host, const char *ip,
797: const struct sshkey *key,
798: char **user_hostfiles, u_int num_user_hostfiles,
799: char **system_hostfiles, u_int num_system_hostfiles)
800: {
801: char *ret = NULL, **othernames = NULL;
802: u_int i, n, num_othernames = 0;
803:
804: hostkeys_find_by_key(host, ip, key,
805: user_hostfiles, num_user_hostfiles,
806: system_hostfiles, num_system_hostfiles,
807: &othernames, &num_othernames);
808: if (num_othernames == 0)
809: return xstrdup("This key is not known by any other names");
810:
811: xasprintf(&ret, "This host key is known by the following other "
812: "names/addresses:");
813:
814: n = num_othernames;
815: if (n > MAX_OTHER_NAMES)
816: n = MAX_OTHER_NAMES;
817: for (i = 0; i < n; i++) {
818: xextendf(&ret, "\n", " %s", othernames[i]);
819: }
820: if (n < num_othernames) {
821: xextendf(&ret, "\n", " (%d additional names ommitted)",
822: num_othernames - n);
823: }
824: for (i = 0; i < num_othernames; i++)
825: free(othernames[i]);
826: free(othernames);
827: return ret;
828: }
829:
1.39 deraadt 830: /*
1.108 markus 831: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 832: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 833: */
1.197 dtucker 834: #define RDRW 0
835: #define RDONLY 1
836: #define ROQUIET 2
1.109 itojun 837: static int
1.197 dtucker 838: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 839: struct sshkey *host_key, int readonly,
1.234 djm 840: char **user_hostfiles, u_int num_user_hostfiles,
1.337 djm 841: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 842: {
1.338 djm 843: HostStatus host_status = -1, ip_status = -1;
1.279 markus 844: struct sshkey *raw_key = NULL;
1.189 dtucker 845: char *ip = NULL, *host = NULL;
1.204 grunk 846: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 847: char msg[1024];
1.234 djm 848: const char *type;
1.338 djm 849: const struct hostkey_entry *host_found = NULL, *ip_found = NULL;
1.312 dtucker 850: int len, cancelled_forwarding = 0, confirmed;
1.337 djm 851: int local = sockaddr_is_local(hostaddr);
1.280 markus 852: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 853: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 854: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 855: u_int i;
1.49 markus 856:
857: /*
858: * Force accepting of the host key for loopback/localhost. The
859: * problem is that if the home directory is NFS-mounted to multiple
860: * machines, localhost will refer to a different machine in each of
861: * them, and the user will get bogus HOST_CHANGED warnings. This
862: * essentially disables host authentication for localhost; however,
863: * this is probably not a real problem.
864: */
1.111 markus 865: if (options.no_host_authentication_for_localhost == 1 && local &&
866: options.host_key_alias == NULL) {
1.88 markus 867: debug("Forcing accepting of host key for "
868: "loopback/localhost.");
1.338 djm 869: options.update_hostkeys = 0;
1.108 markus 870: return 0;
1.49 markus 871: }
1.42 markus 872:
873: /*
1.229 djm 874: * Prepare the hostname and address strings used for hostkey lookup.
875: * In some cases, these will have a port number appended.
1.42 markus 876: */
1.229 djm 877: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 878:
879: /*
1.88 markus 880: * Turn off check_host_ip if the connection is to localhost, via proxy
881: * command or if we don't have a hostname to compare with
882: */
1.189 dtucker 883: if (options.check_host_ip && (local ||
884: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 885: options.check_host_ip = 0;
1.86 markus 886:
1.229 djm 887: host_hostkeys = init_hostkeys();
1.234 djm 888: for (i = 0; i < num_user_hostfiles; i++)
889: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
890: for (i = 0; i < num_system_hostfiles; i++)
891: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 892:
893: ip_hostkeys = NULL;
894: if (!want_cert && options.check_host_ip) {
895: ip_hostkeys = init_hostkeys();
1.234 djm 896: for (i = 0; i < num_user_hostfiles; i++)
897: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
898: for (i = 0; i < num_system_hostfiles; i++)
899: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 900: }
1.38 markus 901:
1.219 djm 902: retry:
1.229 djm 903: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 904: want_cert = sshkey_is_cert(host_key);
905: type = sshkey_type(host_key);
1.219 djm 906:
1.46 markus 907: /*
1.170 djm 908: * Check if the host key is present in the user's list of known
1.40 markus 909: * hosts or in the systemwide list.
910: */
1.229 djm 911: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
912: &host_found);
913:
1.40 markus 914: /*
915: * Also perform check for the ip address, skip the check if we are
1.219 djm 916: * localhost, looking for a certificate, or the hostname was an ip
917: * address to begin with.
1.40 markus 918: */
1.229 djm 919: if (!want_cert && ip_hostkeys != NULL) {
920: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
921: &ip_found);
1.38 markus 922: if (host_status == HOST_CHANGED &&
1.319 djm 923: (ip_status != HOST_CHANGED ||
1.229 djm 924: (ip_found != NULL &&
1.280 markus 925: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 926: host_ip_differ = 1;
927: } else
928: ip_status = host_status;
929:
930: switch (host_status) {
931: case HOST_OK:
932: /* The host is known and the key matches. */
1.219 djm 933: debug("Host '%.200s' is known and matches the %s host %s.",
934: host, type, want_cert ? "certificate" : "key");
1.229 djm 935: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
936: host_found->file, host_found->line);
1.281 djm 937: if (want_cert &&
938: !check_host_cert(options.host_key_alias == NULL ?
939: hostname : options.host_key_alias, host_key))
1.219 djm 940: goto fail;
1.338 djm 941: /* Turn off UpdateHostkeys if key was in system known_hosts */
942: if (options.update_hostkeys != 0 &&
943: (path_in_hostfiles(host_found->file,
944: system_hostfiles, num_system_hostfiles) ||
945: (ip_status == HOST_OK && ip_found != NULL &&
946: path_in_hostfiles(ip_found->file,
947: system_hostfiles, num_system_hostfiles)))) {
948: options.update_hostkeys = 0;
1.341 djm 949: debug3_f("host key found in GlobalKnownHostsFile; "
950: "disabling UpdateHostkeys");
1.338 djm 951: }
1.88 markus 952: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 953: if (readonly || want_cert)
1.138 itojun 954: logit("%s host key for IP address "
1.108 markus 955: "'%.128s' not in list of known hosts.",
956: type, ip);
1.234 djm 957: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 958: host_key, options.hash_known_hosts))
1.138 itojun 959: logit("Failed to add the %s host key for IP "
1.108 markus 960: "address '%.128s' to the list of known "
1.262 dtucker 961: "hosts (%.500s).", type, ip,
1.234 djm 962: user_hostfiles[0]);
1.88 markus 963: else
1.138 itojun 964: logit("Warning: Permanently added the %s host "
1.108 markus 965: "key for IP address '%.128s' to the list "
966: "of known hosts.", type, ip);
1.209 grunk 967: } else if (options.visual_host_key) {
1.259 djm 968: fp = sshkey_fingerprint(host_key,
1.254 djm 969: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 970: ra = sshkey_fingerprint(host_key,
1.254 djm 971: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 972: if (fp == NULL || ra == NULL)
1.341 djm 973: fatal_f("sshkey_fingerprint failed");
1.264 djm 974: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 975: free(ra);
976: free(fp);
1.38 markus 977: }
1.257 djm 978: hostkey_trusted = 1;
1.38 markus 979: break;
980: case HOST_NEW:
1.197 dtucker 981: if (options.host_key_alias == NULL && port != 0 &&
982: port != SSH_DEFAULT_PORT) {
983: debug("checking without port identifier");
1.212 stevesk 984: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 985: ROQUIET, user_hostfiles, num_user_hostfiles,
1.337 djm 986: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 987: debug("found matching key w/out port");
988: break;
989: }
990: }
1.219 djm 991: if (readonly || want_cert)
1.108 markus 992: goto fail;
1.38 markus 993: /* The host is new. */
1.285 djm 994: if (options.strict_host_key_checking ==
995: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 996: /*
997: * User has requested strict host key checking. We
998: * will not add the host key automatically. The only
999: * alternative left is to abort.
1000: */
1001: error("No %s host key is known for %.200s and you "
1002: "have requested strict checking.", type, host);
1003: goto fail;
1.285 djm 1004: } else if (options.strict_host_key_checking ==
1005: SSH_STRICT_HOSTKEY_ASK) {
1.342 djm 1006: char *msg1 = NULL, *msg2 = NULL;
1007:
1008: xasprintf(&msg1, "The authenticity of host "
1009: "'%.200s (%s)' can't be established", host, ip);
1010:
1011: if (show_other_keys(host_hostkeys, host_key)) {
1012: xextendf(&msg1, "\n", "but keys of different "
1013: "type are already known for this host.");
1014: } else
1015: xextendf(&msg1, "", ".");
1.145 jakob 1016:
1.259 djm 1017: fp = sshkey_fingerprint(host_key,
1.254 djm 1018: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1019: ra = sshkey_fingerprint(host_key,
1.254 djm 1020: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1021: if (fp == NULL || ra == NULL)
1.341 djm 1022: fatal_f("sshkey_fingerprint failed");
1.342 djm 1023: xextendf(&msg1, "\n", "%s key fingerprint is %s.",
1024: type, fp);
1025: if (options.visual_host_key)
1026: xextendf(&msg1, "\n", "%s", ra);
1.145 jakob 1027: if (options.verify_host_key_dns) {
1.342 djm 1028: xextendf(&msg1, "\n",
1029: "%s host key fingerprint found in DNS.",
1030: matching_host_key_dns ?
1031: "Matching" : "No matching");
1.145 jakob 1032: }
1.342 djm 1033: /* msg2 informs for other names matching this key */
1034: if ((msg2 = other_hostkeys_message(host, ip, host_key,
1035: user_hostfiles, num_user_hostfiles,
1036: system_hostfiles, num_system_hostfiles)) != NULL)
1037: xextendf(&msg1, "\n", "%s", msg2);
1038:
1039: xextendf(&msg1, "\n",
1.108 markus 1040: "Are you sure you want to continue connecting "
1.342 djm 1041: "(yes/no/[fingerprint])? ");
1042:
1043: confirmed = confirm(msg1, fp);
1.238 djm 1044: free(ra);
1045: free(fp);
1.342 djm 1046: free(msg1);
1047: free(msg2);
1.312 dtucker 1048: if (!confirmed)
1.108 markus 1049: goto fail;
1.257 djm 1050: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 1051: }
1.161 djm 1052: /*
1.285 djm 1053: * If in "new" or "off" strict mode, add the key automatically
1054: * to the local known_hosts file.
1.161 djm 1055: */
1.88 markus 1056: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 1057: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 1058: hostp = hostline;
1.161 djm 1059: if (options.hash_known_hosts) {
1060: /* Add hash of host and IP separately */
1.234 djm 1061: r = add_host_to_hostfile(user_hostfiles[0],
1062: host, host_key, options.hash_known_hosts) &&
1063: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 1064: host_key, options.hash_known_hosts);
1065: } else {
1066: /* Add unhashed "host,ip" */
1.234 djm 1067: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 1068: hostline, host_key,
1069: options.hash_known_hosts);
1070: }
1071: } else {
1.234 djm 1072: r = add_host_to_hostfile(user_hostfiles[0], host,
1073: host_key, options.hash_known_hosts);
1.38 markus 1074: hostp = host;
1.161 djm 1075: }
1.38 markus 1076:
1.161 djm 1077: if (!r)
1.138 itojun 1078: logit("Failed to add the host to the list of known "
1.234 djm 1079: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 1080: else
1.138 itojun 1081: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 1082: "list of known hosts.", hostp, type);
1.38 markus 1083: break;
1.220 djm 1084: case HOST_REVOKED:
1085: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1086: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1087: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1088: error("The %s host key for %s is marked as revoked.", type, host);
1089: error("This could mean that a stolen key is being used to");
1090: error("impersonate this host.");
1091:
1092: /*
1093: * If strict host key checking is in use, the user will have
1094: * to edit the key manually and we can only abort.
1095: */
1.285 djm 1096: if (options.strict_host_key_checking !=
1097: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 1098: error("%s host key for %.200s was revoked and you have "
1099: "requested strict checking.", type, host);
1100: goto fail;
1101: }
1102: goto continue_unsafe;
1103:
1.38 markus 1104: case HOST_CHANGED:
1.219 djm 1105: if (want_cert) {
1106: /*
1107: * This is only a debug() since it is valid to have
1108: * CAs with wildcard DNS matches that don't match
1109: * all hosts that one might visit.
1110: */
1111: debug("Host certificate authority does not "
1.229 djm 1112: "match %s in %s:%lu", CA_MARKER,
1113: host_found->file, host_found->line);
1.219 djm 1114: goto fail;
1115: }
1.197 dtucker 1116: if (readonly == ROQUIET)
1117: goto fail;
1.38 markus 1118: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1119: char *key_msg;
1.38 markus 1120: if (ip_status == HOST_NEW)
1.158 avsm 1121: key_msg = "is unknown";
1.38 markus 1122: else if (ip_status == HOST_OK)
1.158 avsm 1123: key_msg = "is unchanged";
1.38 markus 1124: else
1.158 avsm 1125: key_msg = "has a different value";
1.38 markus 1126: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1127: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1128: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1129: error("The %s host key for %s has changed,", type, host);
1.208 ian 1130: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1131: error("%s. This could either mean that", key_msg);
1.38 markus 1132: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1133: error("and its host key have changed at the same time.");
1.88 markus 1134: if (ip_status != HOST_NEW)
1.229 djm 1135: error("Offending key for IP in %s:%lu",
1136: ip_found->file, ip_found->line);
1.38 markus 1137: }
1138: /* The host key has changed. */
1.150 jakob 1139: warn_changed_key(host_key);
1.38 markus 1140: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1141: user_hostfiles[0]);
1.280 markus 1142: error("Offending %s key in %s:%lu",
1143: sshkey_type(host_found->key),
1.229 djm 1144: host_found->file, host_found->line);
1.38 markus 1145:
1.40 markus 1146: /*
1147: * If strict host key checking is in use, the user will have
1148: * to edit the key manually and we can only abort.
1149: */
1.285 djm 1150: if (options.strict_host_key_checking !=
1151: SSH_STRICT_HOSTKEY_OFF) {
1.344 djm 1152: error("Host key for %.200s has changed and you have "
1153: "requested strict checking.", host);
1.108 markus 1154: goto fail;
1155: }
1.38 markus 1156:
1.220 djm 1157: continue_unsafe:
1.40 markus 1158: /*
1159: * If strict host key checking has not been requested, allow
1.144 djm 1160: * the connection but without MITM-able authentication or
1.194 stevesk 1161: * forwarding.
1.40 markus 1162: */
1.38 markus 1163: if (options.password_authentication) {
1.108 markus 1164: error("Password authentication is disabled to avoid "
1165: "man-in-the-middle attacks.");
1.38 markus 1166: options.password_authentication = 0;
1.210 dtucker 1167: cancelled_forwarding = 1;
1.144 djm 1168: }
1169: if (options.kbd_interactive_authentication) {
1170: error("Keyboard-interactive authentication is disabled"
1171: " to avoid man-in-the-middle attacks.");
1172: options.kbd_interactive_authentication = 0;
1173: options.challenge_response_authentication = 0;
1.210 dtucker 1174: cancelled_forwarding = 1;
1.144 djm 1175: }
1176: if (options.challenge_response_authentication) {
1177: error("Challenge/response authentication is disabled"
1178: " to avoid man-in-the-middle attacks.");
1179: options.challenge_response_authentication = 0;
1.210 dtucker 1180: cancelled_forwarding = 1;
1.38 markus 1181: }
1182: if (options.forward_agent) {
1.108 markus 1183: error("Agent forwarding is disabled to avoid "
1184: "man-in-the-middle attacks.");
1.38 markus 1185: options.forward_agent = 0;
1.210 dtucker 1186: cancelled_forwarding = 1;
1.83 markus 1187: }
1188: if (options.forward_x11) {
1.108 markus 1189: error("X11 forwarding is disabled to avoid "
1190: "man-in-the-middle attacks.");
1.83 markus 1191: options.forward_x11 = 0;
1.210 dtucker 1192: cancelled_forwarding = 1;
1.83 markus 1193: }
1.108 markus 1194: if (options.num_local_forwards > 0 ||
1195: options.num_remote_forwards > 0) {
1196: error("Port forwarding is disabled to avoid "
1197: "man-in-the-middle attacks.");
1198: options.num_local_forwards =
1.118 deraadt 1199: options.num_remote_forwards = 0;
1.210 dtucker 1200: cancelled_forwarding = 1;
1.194 stevesk 1201: }
1202: if (options.tun_open != SSH_TUNMODE_NO) {
1203: error("Tunnel forwarding is disabled to avoid "
1204: "man-in-the-middle attacks.");
1205: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1206: cancelled_forwarding = 1;
1.339 djm 1207: }
1208: if (options.update_hostkeys != 0) {
1209: error("UpdateHostkeys is disabled because the host "
1210: "key is not trusted.");
1211: options.update_hostkeys = 0;
1.38 markus 1212: }
1.210 dtucker 1213: if (options.exit_on_forward_failure && cancelled_forwarding)
1214: fatal("Error: forwarding disabled due to host key "
1215: "check failure");
1216:
1.40 markus 1217: /*
1218: * XXX Should permit the user to change to use the new id.
1219: * This could be done by converting the host key to an
1220: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1221: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1222: * accept the authentication.
1223: */
1.38 markus 1224: break;
1.132 markus 1225: case HOST_FOUND:
1226: fatal("internal error");
1227: break;
1.88 markus 1228: }
1229:
1230: if (options.check_host_ip && host_status != HOST_CHANGED &&
1231: ip_status == HOST_CHANGED) {
1.119 markus 1232: snprintf(msg, sizeof(msg),
1233: "Warning: the %s host key for '%.200s' "
1234: "differs from the key for the IP address '%.128s'"
1.229 djm 1235: "\nOffending key for IP in %s:%lu",
1236: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1237: if (host_status == HOST_OK) {
1238: len = strlen(msg);
1239: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1240: "\nMatching host key in %s:%lu",
1241: host_found->file, host_found->line);
1.119 markus 1242: }
1.285 djm 1243: if (options.strict_host_key_checking ==
1244: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1245: strlcat(msg, "\nAre you sure you want "
1246: "to continue connecting (yes/no)? ", sizeof(msg));
1.312 dtucker 1247: if (!confirm(msg, NULL))
1.108 markus 1248: goto fail;
1.285 djm 1249: } else if (options.strict_host_key_checking !=
1250: SSH_STRICT_HOSTKEY_OFF) {
1251: logit("%s", msg);
1252: error("Exiting, you have requested strict checking.");
1253: goto fail;
1.119 markus 1254: } else {
1.143 djm 1255: logit("%s", msg);
1.88 markus 1256: }
1.257 djm 1257: }
1258:
1259: if (!hostkey_trusted && options.update_hostkeys) {
1.341 djm 1260: debug_f("hostkey not known or explicitly trusted: "
1261: "disabling UpdateHostkeys");
1.257 djm 1262: options.update_hostkeys = 0;
1.38 markus 1263: }
1.82 provos 1264:
1.238 djm 1265: free(ip);
1266: free(host);
1.229 djm 1267: if (host_hostkeys != NULL)
1268: free_hostkeys(host_hostkeys);
1269: if (ip_hostkeys != NULL)
1270: free_hostkeys(ip_hostkeys);
1.108 markus 1271: return 0;
1272:
1273: fail:
1.337 djm 1274: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1275: /*
1276: * No matching certificate. Downgrade cert to raw key and
1277: * search normally.
1278: */
1279: debug("No matching CA found. Retry with plain key");
1.280 markus 1280: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1.341 djm 1281: fatal_fr(r, "decode key");
1.280 markus 1282: if ((r = sshkey_drop_cert(raw_key)) != 0)
1.341 djm 1283: fatal_r(r, "Couldn't drop certificate");
1.219 djm 1284: host_key = raw_key;
1285: goto retry;
1286: }
1.293 dtucker 1287: sshkey_free(raw_key);
1.238 djm 1288: free(ip);
1289: free(host);
1.229 djm 1290: if (host_hostkeys != NULL)
1291: free_hostkeys(host_hostkeys);
1292: if (ip_hostkeys != NULL)
1293: free_hostkeys(ip_hostkeys);
1.108 markus 1294: return -1;
1295: }
1296:
1.337 djm 1297: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1298: int
1.337 djm 1299: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1300: {
1.267 djm 1301: u_int i;
1.337 djm 1302: int r = -1, flags = 0;
1.267 djm 1303: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1304: struct sshkey *plain = NULL;
1.229 djm 1305:
1.252 djm 1306: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1307: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.341 djm 1308: error_fr(r, "fingerprint host key");
1.252 djm 1309: r = -1;
1310: goto out;
1311: }
1312:
1.267 djm 1313: if (sshkey_is_cert(host_key)) {
1314: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1315: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.341 djm 1316: error_fr(r, "fingerprint CA key");
1.267 djm 1317: r = -1;
1318: goto out;
1319: }
1320: sshkey_format_cert_validity(host_key->cert,
1321: valid, sizeof(valid));
1322: debug("Server host certificate: %s %s, serial %llu "
1323: "ID \"%s\" CA %s %s valid %s",
1324: sshkey_ssh_name(host_key), fp,
1.269 djm 1325: (unsigned long long)host_key->cert->serial,
1326: host_key->cert->key_id,
1.267 djm 1327: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1328: valid);
1329: for (i = 0; i < host_key->cert->nprincipals; i++) {
1330: debug2("Server host certificate hostname: %s",
1331: host_key->cert->principals[i]);
1332: }
1333: } else {
1.276 djm 1334: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1335: }
1.252 djm 1336:
1337: if (sshkey_equal(previous_host_key, host_key)) {
1.341 djm 1338: debug2_f("server host key %s %s matches cached key",
1339: sshkey_type(host_key), fp);
1.252 djm 1340: r = 0;
1341: goto out;
1342: }
1343:
1344: /* Check in RevokedHostKeys file if specified */
1345: if (options.revoked_host_keys != NULL) {
1346: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1347: switch (r) {
1348: case 0:
1349: break; /* not revoked */
1350: case SSH_ERR_KEY_REVOKED:
1351: error("Host key %s %s revoked by file %s",
1352: sshkey_type(host_key), fp,
1353: options.revoked_host_keys);
1354: r = -1;
1355: goto out;
1356: default:
1.341 djm 1357: error_r(r, "Error checking host key %s %s in "
1358: "revoked keys file %s", sshkey_type(host_key),
1359: fp, options.revoked_host_keys);
1.252 djm 1360: r = -1;
1361: goto out;
1362: }
1.250 djm 1363: }
1364:
1.247 djm 1365: if (options.verify_host_key_dns) {
1366: /*
1367: * XXX certs are not yet supported for DNS, so downgrade
1368: * them and try the plain key.
1369: */
1.252 djm 1370: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1371: goto out;
1372: if (sshkey_is_cert(plain))
1373: sshkey_drop_cert(plain);
1.247 djm 1374: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1375: if (flags & DNS_VERIFY_FOUND) {
1376: if (options.verify_host_key_dns == 1 &&
1377: flags & DNS_VERIFY_MATCH &&
1378: flags & DNS_VERIFY_SECURE) {
1.250 djm 1379: r = 0;
1.252 djm 1380: goto out;
1.247 djm 1381: }
1382: if (flags & DNS_VERIFY_MATCH) {
1383: matching_host_key_dns = 1;
1384: } else {
1.287 djm 1385: warn_changed_key(plain);
1386: error("Update the SSHFP RR in DNS "
1387: "with the new host key to get rid "
1388: "of this message.");
1.247 djm 1389: }
1.153 jakob 1390: }
1.140 jakob 1391: }
1392: }
1.250 djm 1393: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1394: options.user_hostfiles, options.num_user_hostfiles,
1.337 djm 1395: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1396:
1.252 djm 1397: out:
1398: sshkey_free(plain);
1399: free(fp);
1.267 djm 1400: free(cafp);
1.337 djm 1401: if (r == 0 && host_key != NULL) {
1402: sshkey_free(previous_host_key);
1403: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1404: }
1405:
1406: return r;
1.51 markus 1407: }
1.70 markus 1408:
1.51 markus 1409: /*
1410: * Starts a dialog with the server, and authenticates the current user on the
1411: * server. This does not need any extra privileges. The basic connection
1412: * to the server must already have been established before this is called.
1413: * If login fails, this function prints an error and never returns.
1414: * This function does not require super-user privileges.
1415: */
1416: void
1.309 djm 1417: ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost,
1.229 djm 1418: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1419: {
1.241 djm 1420: char *host;
1.70 markus 1421: char *server_user, *local_user;
1.329 djm 1422: int r;
1.70 markus 1423:
1424: local_user = xstrdup(pw->pw_name);
1425: server_user = options.user ? options.user : local_user;
1.51 markus 1426:
1427: /* Convert the user-supplied hostname into all lowercase. */
1428: host = xstrdup(orighost);
1.241 djm 1429: lowercase(host);
1.51 markus 1430:
1431: /* Exchange protocol version identification strings with the server. */
1.329 djm 1432: if ((r = kex_exchange_identification(ssh, timeout_ms, NULL)) != 0)
1433: sshpkt_fatal(ssh, r, "banner exchange");
1.51 markus 1434:
1435: /* Put the connection into non-blocking mode. */
1.309 djm 1436: ssh_packet_set_nonblocking(ssh);
1.51 markus 1437:
1438: /* key exchange */
1439: /* authenticate user */
1.261 dtucker 1440: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.309 djm 1441: ssh_kex2(ssh, host, hostaddr, port);
1442: ssh_userauth2(ssh, local_user, server_user, host, sensitive);
1.238 djm 1443: free(local_user);
1.315 dtucker 1444: free(host);
1.132 markus 1445: }
1446:
1447: /* print all known host keys for a given host, but skip keys of given type */
1448: static int
1.279 markus 1449: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1450: {
1.242 djm 1451: int type[] = {
1452: KEY_RSA,
1453: KEY_DSA,
1454: KEY_ECDSA,
1455: KEY_ED25519,
1.297 markus 1456: KEY_XMSS,
1.242 djm 1457: -1
1458: };
1.229 djm 1459: int i, ret = 0;
1460: char *fp, *ra;
1461: const struct hostkey_entry *found;
1.132 markus 1462:
1463: for (i = 0; type[i] != -1; i++) {
1464: if (type[i] == key->type)
1465: continue;
1.335 djm 1466: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i],
1467: -1, &found))
1.132 markus 1468: continue;
1.259 djm 1469: fp = sshkey_fingerprint(found->key,
1.254 djm 1470: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1471: ra = sshkey_fingerprint(found->key,
1.254 djm 1472: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1473: if (fp == NULL || ra == NULL)
1.341 djm 1474: fatal_f("sshkey_fingerprint fail");
1.229 djm 1475: logit("WARNING: %s key found for host %s\n"
1476: "in %s:%lu\n"
1477: "%s key fingerprint %s.",
1.300 markus 1478: sshkey_type(found->key),
1.229 djm 1479: found->host, found->file, found->line,
1.300 markus 1480: sshkey_type(found->key), fp);
1.229 djm 1481: if (options.visual_host_key)
1482: logit("%s", ra);
1.238 djm 1483: free(ra);
1484: free(fp);
1.229 djm 1485: ret = 1;
1.132 markus 1486: }
1.229 djm 1487: return ret;
1.150 jakob 1488: }
1489:
1490: static void
1.279 markus 1491: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1492: {
1493: char *fp;
1494:
1.259 djm 1495: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1496: SSH_FP_DEFAULT);
1.259 djm 1497: if (fp == NULL)
1.341 djm 1498: fatal_f("sshkey_fingerprint fail");
1.150 jakob 1499:
1500: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1501: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1502: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1503: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1504: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1505: error("It is also possible that a host key has just been changed.");
1.150 jakob 1506: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.300 markus 1507: sshkey_type(host_key), fp);
1.150 jakob 1508: error("Please contact your system administrator.");
1509:
1.238 djm 1510: free(fp);
1.171 reyk 1511: }
1512:
1513: /*
1514: * Execute a local command
1515: */
1516: int
1517: ssh_local_cmd(const char *args)
1518: {
1519: char *shell;
1520: pid_t pid;
1521: int status;
1.231 djm 1522: void (*osighand)(int);
1.171 reyk 1523:
1524: if (!options.permit_local_command ||
1525: args == NULL || !*args)
1526: return (1);
1527:
1.226 djm 1528: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1529: shell = _PATH_BSHELL;
1530:
1.327 dtucker 1531: osighand = ssh_signal(SIGCHLD, SIG_DFL);
1.171 reyk 1532: pid = fork();
1533: if (pid == 0) {
1.327 dtucker 1534: ssh_signal(SIGPIPE, SIG_DFL);
1.171 reyk 1535: debug3("Executing %s -c \"%s\"", shell, args);
1536: execl(shell, shell, "-c", args, (char *)NULL);
1537: error("Couldn't execute %s -c \"%s\": %s",
1538: shell, args, strerror(errno));
1539: _exit(1);
1540: } else if (pid == -1)
1541: fatal("fork failed: %.100s", strerror(errno));
1542: while (waitpid(pid, &status, 0) == -1)
1543: if (errno != EINTR)
1544: fatal("Couldn't wait for child: %s", strerror(errno));
1.327 dtucker 1545: ssh_signal(SIGCHLD, osighand);
1.171 reyk 1546:
1547: if (!WIFEXITED(status))
1548: return (1);
1549:
1550: return (WEXITSTATUS(status));
1.266 jcs 1551: }
1552:
1553: void
1.328 djm 1554: maybe_add_key_to_agent(const char *authfile, struct sshkey *private,
1555: const char *comment, const char *passphrase)
1.266 jcs 1556: {
1557: int auth_sock = -1, r;
1.321 djm 1558: const char *skprovider = NULL;
1.266 jcs 1559:
1560: if (options.add_keys_to_agent == 0)
1561: return;
1562:
1563: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1564: debug3("no authentication agent, not adding key");
1565: return;
1566: }
1567:
1568: if (options.add_keys_to_agent == 2 &&
1569: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1570: debug3("user denied adding this key");
1.273 dtucker 1571: close(auth_sock);
1.266 jcs 1572: return;
1573: }
1.322 markus 1574: if (sshkey_is_sk(private))
1.321 djm 1575: skprovider = options.sk_provider;
1.328 djm 1576: if ((r = ssh_add_identity_constrained(auth_sock, private,
1.331 djm 1577: comment == NULL ? authfile : comment,
1578: options.add_keys_to_agent_lifespan,
1.321 djm 1579: (options.add_keys_to_agent == 3), 0, skprovider)) == 0)
1.266 jcs 1580: debug("identity added to agent: %s", authfile);
1581: else
1582: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1583: close(auth_sock);
1.1 deraadt 1584: }
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