Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.341
1.341 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.340 2020/10/12 08:36:37 kn 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)
1.341 ! djm 143: error_f("stdfd_devnull failed");
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)
1.341 ! djm 226: error_f("stdfd_devnull failed");
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)) {
1.341 ! djm 304: error_f("v4 addr doesn't fit");
1.295 djm 305: return -1;
306: }
307: *rlenp = sizeof(struct sockaddr_in);
308: memcpy(resultp, sa, *rlenp);
309: return 0;
310: case AF_INET6:
311: sa6 = (struct sockaddr_in6 *)ifa->ifa_addr;
312: v6addr = &sa6->sin6_addr;
313: if (!allow_local &&
314: (IN6_IS_ADDR_LINKLOCAL(v6addr) ||
315: IN6_IS_ADDR_LOOPBACK(v6addr)))
316: continue;
317: if (*rlenp < sizeof(struct sockaddr_in6)) {
1.341 ! djm 318: error_f("v6 addr doesn't fit");
1.295 djm 319: return -1;
320: }
321: *rlenp = sizeof(struct sockaddr_in6);
322: memcpy(resultp, sa6, *rlenp);
323: return 0;
324: }
325: }
326: }
327: return -1;
328: }
329:
330: /*
1.303 dtucker 331: * Creates a socket for use as the ssh connection.
1.39 deraadt 332: */
1.109 itojun 333: static int
1.302 dtucker 334: ssh_create_socket(struct addrinfo *ai)
1.1 deraadt 335: {
1.301 dtucker 336: int sock, r;
1.295 djm 337: struct sockaddr_storage bindaddr;
338: socklen_t bindaddrlen = 0;
1.246 djm 339: struct addrinfo hints, *res = NULL;
1.295 djm 340: struct ifaddrs *ifaddrs = NULL;
341: char ntop[NI_MAXHOST];
1.1 deraadt 342:
1.217 dtucker 343: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.317 deraadt 344: if (sock == -1) {
1.240 djm 345: error("socket: %s", strerror(errno));
1.216 dtucker 346: return -1;
347: }
348: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 349:
350: /* Bind the socket to an alternative local IP address */
1.302 dtucker 351: if (options.bind_address == NULL && options.bind_interface == NULL)
1.105 markus 352: return sock;
353:
1.295 djm 354: if (options.bind_address != NULL) {
1.246 djm 355: memset(&hints, 0, sizeof(hints));
356: hints.ai_family = ai->ai_family;
357: hints.ai_socktype = ai->ai_socktype;
358: hints.ai_protocol = ai->ai_protocol;
359: hints.ai_flags = AI_PASSIVE;
1.295 djm 360: if ((r = getaddrinfo(options.bind_address, NULL,
361: &hints, &res)) != 0) {
1.246 djm 362: error("getaddrinfo: %s: %s", options.bind_address,
1.295 djm 363: ssh_gai_strerror(r));
364: goto fail;
365: }
1.296 dtucker 366: if (res == NULL) {
1.295 djm 367: error("getaddrinfo: no addrs");
368: goto fail;
369: }
370: memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
371: bindaddrlen = res->ai_addrlen;
372: } else if (options.bind_interface != NULL) {
373: if ((r = getifaddrs(&ifaddrs)) != 0) {
374: error("getifaddrs: %s: %s", options.bind_interface,
375: strerror(errno));
376: goto fail;
377: }
378: bindaddrlen = sizeof(bindaddr);
379: if (check_ifaddrs(options.bind_interface, ai->ai_family,
380: ifaddrs, &bindaddr, &bindaddrlen) != 0) {
381: logit("getifaddrs: %s: no suitable addresses",
382: options.bind_interface);
383: goto fail;
1.246 djm 384: }
1.105 markus 385: }
1.295 djm 386: if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
387: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
1.341 ! djm 388: error_f("getnameinfo failed: %s", ssh_gai_strerror(r));
1.295 djm 389: goto fail;
390: }
1.301 dtucker 391: if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
1.295 djm 392: error("bind %s: %s", ntop, strerror(errno));
393: goto fail;
1.38 markus 394: }
1.341 ! djm 395: debug_f("bound to %s", ntop);
1.295 djm 396: /* success */
397: goto out;
398: fail:
399: close(sock);
400: sock = -1;
401: out:
1.246 djm 402: if (res != NULL)
403: freeaddrinfo(res);
1.295 djm 404: if (ifaddrs != NULL)
405: freeifaddrs(ifaddrs);
1.38 markus 406: return sock;
1.1 deraadt 407: }
408:
1.282 djm 409: /*
1.49 markus 410: * Opens a TCP/IP connection to the remote server on the given host.
411: * The address of the remote host will be returned in hostaddr.
1.302 dtucker 412: * If port is 0, the default port will be used.
1.39 deraadt 413: * Connection_attempts specifies the maximum number of tries (one per
414: * second). If proxy_command is non-NULL, it specifies the command (with %h
415: * and %p substituted for host and port, respectively) to use to contact
416: * the daemon.
417: */
1.241 djm 418: static int
1.286 djm 419: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.340 kn 420: struct sockaddr_storage *hostaddr, u_short port, int connection_attempts,
421: int *timeout_ms, int want_keepalive)
1.1 deraadt 422: {
1.313 dtucker 423: int on = 1, saved_timeout_ms = *timeout_ms;
1.290 djm 424: int oerrno, sock = -1, attempt;
1.90 markus 425: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 426: struct addrinfo *ai;
1.38 markus 427:
1.341 ! djm 428: debug3_f("entering");
1.268 djm 429: memset(ntop, 0, sizeof(ntop));
430: memset(strport, 0, sizeof(strport));
1.38 markus 431:
1.181 markus 432: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 433: if (attempt > 0) {
434: /* Sleep a moment before retrying. */
435: sleep(1);
1.38 markus 436: debug("Trying again...");
1.200 markus 437: }
1.181 markus 438: /*
439: * Loop through addresses for this host, and try each one in
440: * sequence until the connection succeeds.
441: */
1.49 markus 442: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 443: if (ai->ai_family != AF_INET &&
1.290 djm 444: ai->ai_family != AF_INET6) {
445: errno = EAFNOSUPPORT;
1.49 markus 446: continue;
1.290 djm 447: }
1.49 markus 448: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
449: ntop, sizeof(ntop), strport, sizeof(strport),
450: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.290 djm 451: oerrno = errno;
1.341 ! djm 452: error_f("getnameinfo failed");
1.290 djm 453: errno = oerrno;
1.49 markus 454: continue;
455: }
456: debug("Connecting to %.200s [%.100s] port %s.",
457: host, ntop, strport);
458:
459: /* Create a socket for connecting. */
1.302 dtucker 460: sock = ssh_create_socket(ai);
1.292 stsp 461: if (sock < 0) {
1.110 markus 462: /* Any error is already output */
1.290 djm 463: errno = 0;
1.49 markus 464: continue;
1.292 stsp 465: }
1.49 markus 466:
1.313 dtucker 467: *timeout_ms = saved_timeout_ms;
1.141 djm 468: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 469: timeout_ms) >= 0) {
1.49 markus 470: /* Successful connection. */
1.102 markus 471: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 472: break;
1.49 markus 473: } else {
1.290 djm 474: oerrno = errno;
1.131 itojun 475: debug("connect to address %s port %s: %s",
476: ntop, strport, strerror(errno));
1.38 markus 477: close(sock);
1.181 markus 478: sock = -1;
1.290 djm 479: errno = oerrno;
1.38 markus 480: }
481: }
1.181 markus 482: if (sock != -1)
1.49 markus 483: break; /* Successful connection. */
1.38 markus 484: }
1.49 markus 485:
1.38 markus 486: /* Return failure if we didn't get a successful connection. */
1.181 markus 487: if (sock == -1) {
1.159 markus 488: error("ssh: connect to host %s port %s: %s",
1.290 djm 489: host, strport, errno == 0 ? "failure" : strerror(errno));
490: return -1;
1.130 itojun 491: }
1.38 markus 492:
493: debug("Connection established.");
1.90 markus 494:
1.155 markus 495: /* Set SO_KEEPALIVE if requested. */
1.202 djm 496: if (want_keepalive &&
1.90 markus 497: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1.317 deraadt 498: sizeof(on)) == -1)
1.90 markus 499: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 500:
501: /* Set the connection. */
1.286 djm 502: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
503: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 504:
1.319 djm 505: return 0;
1.59 markus 506: }
507:
1.241 djm 508: int
1.318 djm 509: ssh_connect(struct ssh *ssh, const char *host, const char *host_arg,
510: struct addrinfo *addrs, struct sockaddr_storage *hostaddr, u_short port,
1.340 kn 511: int connection_attempts, int *timeout_ms, int want_keepalive)
1.241 djm 512: {
1.314 markus 513: int in, out;
514:
1.241 djm 515: if (options.proxy_command == NULL) {
1.286 djm 516: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
1.340 kn 517: connection_attempts, timeout_ms, want_keepalive);
1.241 djm 518: } else if (strcmp(options.proxy_command, "-") == 0) {
1.317 deraadt 519: if ((in = dup(STDIN_FILENO)) == -1 ||
520: (out = dup(STDOUT_FILENO)) == -1) {
1.314 markus 521: if (in >= 0)
522: close(in);
1.341 ! djm 523: error_f("dup() in/out failed");
1.314 markus 524: return -1; /* ssh_packet_set_connection logs error */
525: }
526: if ((ssh_packet_set_connection(ssh, in, out)) == NULL)
1.286 djm 527: return -1; /* ssh_packet_set_connection logs error */
528: return 0;
1.241 djm 529: } else if (options.proxy_use_fdpass) {
1.318 djm 530: return ssh_proxy_fdpass_connect(ssh, host, host_arg, port,
1.241 djm 531: options.proxy_command);
532: }
1.318 djm 533: return ssh_proxy_connect(ssh, host, host_arg, port,
534: options.proxy_command);
1.241 djm 535: }
536:
1.96 markus 537: /* defaults to 'no' */
1.109 itojun 538: static int
1.312 dtucker 539: confirm(const char *prompt, const char *fingerprint)
1.1 deraadt 540: {
1.119 markus 541: const char *msg, *again = "Please type 'yes' or 'no': ";
1.312 dtucker 542: const char *again_fp = "Please type 'yes', 'no' or the fingerprint: ";
1.326 dtucker 543: char *p, *cp;
1.119 markus 544: int ret = -1;
1.96 markus 545:
546: if (options.batch_mode)
547: return 0;
1.312 dtucker 548: for (msg = prompt;;msg = fingerprint ? again_fp : again) {
1.326 dtucker 549: cp = p = read_passphrase(msg, RP_ECHO);
1.289 djm 550: if (p == NULL)
551: return 0;
1.326 dtucker 552: p += strspn(p, " \t"); /* skip leading whitespace */
553: p[strcspn(p, " \t\n")] = '\0'; /* remove trailing whitespace */
1.289 djm 554: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 555: ret = 0;
1.312 dtucker 556: else if (strcasecmp(p, "yes") == 0 || (fingerprint != NULL &&
1.332 djm 557: strcmp(p, fingerprint) == 0))
1.119 markus 558: ret = 1;
1.326 dtucker 559: free(cp);
1.119 markus 560: if (ret != -1)
561: return ret;
1.1 deraadt 562: }
563: }
564:
1.219 djm 565: static int
1.305 djm 566: check_host_cert(const char *host, const struct sshkey *key)
1.219 djm 567: {
568: const char *reason;
1.305 djm 569: int r;
1.219 djm 570:
1.305 djm 571: if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) {
1.219 djm 572: error("%s", reason);
573: return 0;
574: }
1.305 djm 575: if (sshbuf_len(key->cert->critical) != 0) {
1.223 djm 576: error("Certificate for %s contains unsupported "
577: "critical options(s)", host);
1.219 djm 578: return 0;
579: }
1.305 djm 580: if ((r = sshkey_check_cert_sigtype(key,
581: options.ca_sign_algorithms)) != 0) {
1.341 ! djm 582: logit_fr(r, "certificate signature algorithm %s",
1.305 djm 583: (key->cert == NULL || key->cert->signature_type == NULL) ?
1.341 ! djm 584: "(null)" : key->cert->signature_type);
1.305 djm 585: return 0;
586: }
1.336 djm 587: /* Do not attempt hostkey update if a certificate was successful */
588: if (options.update_hostkeys != 0) {
589: options.update_hostkeys = 0;
1.341 ! djm 590: debug3_f("certificate host key in use; disabling UpdateHostkeys");
1.336 djm 591: }
1.219 djm 592: return 1;
593: }
594:
1.229 djm 595: static int
596: sockaddr_is_local(struct sockaddr *hostaddr)
597: {
598: switch (hostaddr->sa_family) {
599: case AF_INET:
600: return (ntohl(((struct sockaddr_in *)hostaddr)->
601: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
602: case AF_INET6:
603: return IN6_IS_ADDR_LOOPBACK(
604: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
605: default:
606: return 0;
607: }
608: }
609:
610: /*
611: * Prepare the hostname and ip address strings that are used to lookup
612: * host keys in known_hosts files. These may have a port number appended.
613: */
614: void
615: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
616: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
617: {
618: char ntop[NI_MAXHOST];
619:
620: /*
621: * We don't have the remote ip-address for connections
622: * using a proxy command
623: */
624: if (hostfile_ipaddr != NULL) {
625: if (options.proxy_command == NULL) {
626: if (getnameinfo(hostaddr, hostaddr->sa_len,
627: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.341 ! djm 628: fatal_f("getnameinfo failed");
1.229 djm 629: *hostfile_ipaddr = put_host_port(ntop, port);
630: } else {
631: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
632: "command>");
633: }
634: }
635:
636: /*
637: * Allow the user to record the key under a different name or
638: * differentiate a non-standard port. This is useful for ssh
639: * tunneling over forwarded connections or if you run multiple
640: * sshd's on different ports on the same machine.
641: */
642: if (hostfile_hostname != NULL) {
643: if (options.host_key_alias != NULL) {
644: *hostfile_hostname = xstrdup(options.host_key_alias);
645: debug("using hostkeyalias: %s", *hostfile_hostname);
646: } else {
647: *hostfile_hostname = put_host_port(hostname, port);
648: }
649: }
650: }
651:
1.338 djm 652: /* returns non-zero if path appears in hostfiles, or 0 if not. */
653: static int
654: path_in_hostfiles(const char *path, char **hostfiles, u_int num_hostfiles)
655: {
656: u_int i;
657:
658: for (i = 0; i < num_hostfiles; i++) {
659: if (strcmp(path, hostfiles[i]) == 0)
660: return 1;
661: }
662: return 0;
663: }
664:
1.39 deraadt 665: /*
1.108 markus 666: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 667: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 668: */
1.197 dtucker 669: #define RDRW 0
670: #define RDONLY 1
671: #define ROQUIET 2
1.109 itojun 672: static int
1.197 dtucker 673: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 674: struct sshkey *host_key, int readonly,
1.234 djm 675: char **user_hostfiles, u_int num_user_hostfiles,
1.337 djm 676: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 677: {
1.338 djm 678: HostStatus host_status = -1, ip_status = -1;
1.279 markus 679: struct sshkey *raw_key = NULL;
1.189 dtucker 680: char *ip = NULL, *host = NULL;
1.204 grunk 681: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 682: char msg[1024];
1.234 djm 683: const char *type;
1.338 djm 684: const struct hostkey_entry *host_found = NULL, *ip_found = NULL;
1.312 dtucker 685: int len, cancelled_forwarding = 0, confirmed;
1.337 djm 686: int local = sockaddr_is_local(hostaddr);
1.280 markus 687: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 688: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 689: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 690: u_int i;
1.49 markus 691:
692: /*
693: * Force accepting of the host key for loopback/localhost. The
694: * problem is that if the home directory is NFS-mounted to multiple
695: * machines, localhost will refer to a different machine in each of
696: * them, and the user will get bogus HOST_CHANGED warnings. This
697: * essentially disables host authentication for localhost; however,
698: * this is probably not a real problem.
699: */
1.111 markus 700: if (options.no_host_authentication_for_localhost == 1 && local &&
701: options.host_key_alias == NULL) {
1.88 markus 702: debug("Forcing accepting of host key for "
703: "loopback/localhost.");
1.338 djm 704: options.update_hostkeys = 0;
1.108 markus 705: return 0;
1.49 markus 706: }
1.42 markus 707:
708: /*
1.229 djm 709: * Prepare the hostname and address strings used for hostkey lookup.
710: * In some cases, these will have a port number appended.
1.42 markus 711: */
1.229 djm 712: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 713:
714: /*
1.88 markus 715: * Turn off check_host_ip if the connection is to localhost, via proxy
716: * command or if we don't have a hostname to compare with
717: */
1.189 dtucker 718: if (options.check_host_ip && (local ||
719: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 720: options.check_host_ip = 0;
1.86 markus 721:
1.229 djm 722: host_hostkeys = init_hostkeys();
1.234 djm 723: for (i = 0; i < num_user_hostfiles; i++)
724: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
725: for (i = 0; i < num_system_hostfiles; i++)
726: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 727:
728: ip_hostkeys = NULL;
729: if (!want_cert && options.check_host_ip) {
730: ip_hostkeys = init_hostkeys();
1.234 djm 731: for (i = 0; i < num_user_hostfiles; i++)
732: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
733: for (i = 0; i < num_system_hostfiles; i++)
734: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 735: }
1.38 markus 736:
1.219 djm 737: retry:
1.229 djm 738: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 739: want_cert = sshkey_is_cert(host_key);
740: type = sshkey_type(host_key);
1.219 djm 741:
1.46 markus 742: /*
1.170 djm 743: * Check if the host key is present in the user's list of known
1.40 markus 744: * hosts or in the systemwide list.
745: */
1.229 djm 746: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
747: &host_found);
748:
1.40 markus 749: /*
750: * Also perform check for the ip address, skip the check if we are
1.219 djm 751: * localhost, looking for a certificate, or the hostname was an ip
752: * address to begin with.
1.40 markus 753: */
1.229 djm 754: if (!want_cert && ip_hostkeys != NULL) {
755: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
756: &ip_found);
1.38 markus 757: if (host_status == HOST_CHANGED &&
1.319 djm 758: (ip_status != HOST_CHANGED ||
1.229 djm 759: (ip_found != NULL &&
1.280 markus 760: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 761: host_ip_differ = 1;
762: } else
763: ip_status = host_status;
764:
765: switch (host_status) {
766: case HOST_OK:
767: /* The host is known and the key matches. */
1.219 djm 768: debug("Host '%.200s' is known and matches the %s host %s.",
769: host, type, want_cert ? "certificate" : "key");
1.229 djm 770: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
771: host_found->file, host_found->line);
1.281 djm 772: if (want_cert &&
773: !check_host_cert(options.host_key_alias == NULL ?
774: hostname : options.host_key_alias, host_key))
1.219 djm 775: goto fail;
1.338 djm 776: /* Turn off UpdateHostkeys if key was in system known_hosts */
777: if (options.update_hostkeys != 0 &&
778: (path_in_hostfiles(host_found->file,
779: system_hostfiles, num_system_hostfiles) ||
780: (ip_status == HOST_OK && ip_found != NULL &&
781: path_in_hostfiles(ip_found->file,
782: system_hostfiles, num_system_hostfiles)))) {
783: options.update_hostkeys = 0;
1.341 ! djm 784: debug3_f("host key found in GlobalKnownHostsFile; "
! 785: "disabling UpdateHostkeys");
1.338 djm 786: }
1.88 markus 787: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 788: if (readonly || want_cert)
1.138 itojun 789: logit("%s host key for IP address "
1.108 markus 790: "'%.128s' not in list of known hosts.",
791: type, ip);
1.234 djm 792: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 793: host_key, options.hash_known_hosts))
1.138 itojun 794: logit("Failed to add the %s host key for IP "
1.108 markus 795: "address '%.128s' to the list of known "
1.262 dtucker 796: "hosts (%.500s).", type, ip,
1.234 djm 797: user_hostfiles[0]);
1.88 markus 798: else
1.138 itojun 799: logit("Warning: Permanently added the %s host "
1.108 markus 800: "key for IP address '%.128s' to the list "
801: "of known hosts.", type, ip);
1.209 grunk 802: } else if (options.visual_host_key) {
1.259 djm 803: fp = sshkey_fingerprint(host_key,
1.254 djm 804: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 805: ra = sshkey_fingerprint(host_key,
1.254 djm 806: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 807: if (fp == NULL || ra == NULL)
1.341 ! djm 808: fatal_f("sshkey_fingerprint failed");
1.264 djm 809: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 810: free(ra);
811: free(fp);
1.38 markus 812: }
1.257 djm 813: hostkey_trusted = 1;
1.38 markus 814: break;
815: case HOST_NEW:
1.197 dtucker 816: if (options.host_key_alias == NULL && port != 0 &&
817: port != SSH_DEFAULT_PORT) {
818: debug("checking without port identifier");
1.212 stevesk 819: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 820: ROQUIET, user_hostfiles, num_user_hostfiles,
1.337 djm 821: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 822: debug("found matching key w/out port");
823: break;
824: }
825: }
1.219 djm 826: if (readonly || want_cert)
1.108 markus 827: goto fail;
1.38 markus 828: /* The host is new. */
1.285 djm 829: if (options.strict_host_key_checking ==
830: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 831: /*
832: * User has requested strict host key checking. We
833: * will not add the host key automatically. The only
834: * alternative left is to abort.
835: */
836: error("No %s host key is known for %.200s and you "
837: "have requested strict checking.", type, host);
838: goto fail;
1.285 djm 839: } else if (options.strict_host_key_checking ==
840: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 841: char msg1[1024], msg2[1024];
842:
1.229 djm 843: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 844: snprintf(msg1, sizeof(msg1),
1.168 djm 845: "\nbut keys of different type are already"
846: " known for this host.");
1.145 jakob 847: else
848: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 849: /* The default */
1.259 djm 850: fp = sshkey_fingerprint(host_key,
1.254 djm 851: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 852: ra = sshkey_fingerprint(host_key,
1.254 djm 853: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 854: if (fp == NULL || ra == NULL)
1.341 ! djm 855: fatal_f("sshkey_fingerprint failed");
1.145 jakob 856: msg2[0] = '\0';
857: if (options.verify_host_key_dns) {
1.153 jakob 858: if (matching_host_key_dns)
1.145 jakob 859: snprintf(msg2, sizeof(msg2),
860: "Matching host key fingerprint"
861: " found in DNS.\n");
862: else
863: snprintf(msg2, sizeof(msg2),
864: "No matching host key fingerprint"
865: " found in DNS.\n");
866: }
1.119 markus 867: snprintf(msg, sizeof(msg),
1.108 markus 868: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 869: "established%s\n"
1.209 grunk 870: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 871: "Are you sure you want to continue connecting "
1.312 dtucker 872: "(yes/no/[fingerprint])? ",
1.209 grunk 873: host, ip, msg1, type, fp,
874: options.visual_host_key ? "\n" : "",
875: options.visual_host_key ? ra : "",
876: msg2);
1.238 djm 877: free(ra);
1.312 dtucker 878: confirmed = confirm(msg, fp);
1.238 djm 879: free(fp);
1.312 dtucker 880: if (!confirmed)
1.108 markus 881: goto fail;
1.257 djm 882: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 883: }
1.161 djm 884: /*
1.285 djm 885: * If in "new" or "off" strict mode, add the key automatically
886: * to the local known_hosts file.
1.161 djm 887: */
1.88 markus 888: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 889: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 890: hostp = hostline;
1.161 djm 891: if (options.hash_known_hosts) {
892: /* Add hash of host and IP separately */
1.234 djm 893: r = add_host_to_hostfile(user_hostfiles[0],
894: host, host_key, options.hash_known_hosts) &&
895: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 896: host_key, options.hash_known_hosts);
897: } else {
898: /* Add unhashed "host,ip" */
1.234 djm 899: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 900: hostline, host_key,
901: options.hash_known_hosts);
902: }
903: } else {
1.234 djm 904: r = add_host_to_hostfile(user_hostfiles[0], host,
905: host_key, options.hash_known_hosts);
1.38 markus 906: hostp = host;
1.161 djm 907: }
1.38 markus 908:
1.161 djm 909: if (!r)
1.138 itojun 910: logit("Failed to add the host to the list of known "
1.234 djm 911: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 912: else
1.138 itojun 913: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 914: "list of known hosts.", hostp, type);
1.38 markus 915: break;
1.220 djm 916: case HOST_REVOKED:
917: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
918: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
919: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
920: error("The %s host key for %s is marked as revoked.", type, host);
921: error("This could mean that a stolen key is being used to");
922: error("impersonate this host.");
923:
924: /*
925: * If strict host key checking is in use, the user will have
926: * to edit the key manually and we can only abort.
927: */
1.285 djm 928: if (options.strict_host_key_checking !=
929: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 930: error("%s host key for %.200s was revoked and you have "
931: "requested strict checking.", type, host);
932: goto fail;
933: }
934: goto continue_unsafe;
935:
1.38 markus 936: case HOST_CHANGED:
1.219 djm 937: if (want_cert) {
938: /*
939: * This is only a debug() since it is valid to have
940: * CAs with wildcard DNS matches that don't match
941: * all hosts that one might visit.
942: */
943: debug("Host certificate authority does not "
1.229 djm 944: "match %s in %s:%lu", CA_MARKER,
945: host_found->file, host_found->line);
1.219 djm 946: goto fail;
947: }
1.197 dtucker 948: if (readonly == ROQUIET)
949: goto fail;
1.38 markus 950: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 951: char *key_msg;
1.38 markus 952: if (ip_status == HOST_NEW)
1.158 avsm 953: key_msg = "is unknown";
1.38 markus 954: else if (ip_status == HOST_OK)
1.158 avsm 955: key_msg = "is unchanged";
1.38 markus 956: else
1.158 avsm 957: key_msg = "has a different value";
1.38 markus 958: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
959: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
960: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 961: error("The %s host key for %s has changed,", type, host);
1.208 ian 962: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 963: error("%s. This could either mean that", key_msg);
1.38 markus 964: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 965: error("and its host key have changed at the same time.");
1.88 markus 966: if (ip_status != HOST_NEW)
1.229 djm 967: error("Offending key for IP in %s:%lu",
968: ip_found->file, ip_found->line);
1.38 markus 969: }
970: /* The host key has changed. */
1.150 jakob 971: warn_changed_key(host_key);
1.38 markus 972: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 973: user_hostfiles[0]);
1.280 markus 974: error("Offending %s key in %s:%lu",
975: sshkey_type(host_found->key),
1.229 djm 976: host_found->file, host_found->line);
1.38 markus 977:
1.40 markus 978: /*
979: * If strict host key checking is in use, the user will have
980: * to edit the key manually and we can only abort.
981: */
1.285 djm 982: if (options.strict_host_key_checking !=
983: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 984: error("%s host key for %.200s has changed and you have "
985: "requested strict checking.", type, host);
986: goto fail;
987: }
1.38 markus 988:
1.220 djm 989: continue_unsafe:
1.40 markus 990: /*
991: * If strict host key checking has not been requested, allow
1.144 djm 992: * the connection but without MITM-able authentication or
1.194 stevesk 993: * forwarding.
1.40 markus 994: */
1.38 markus 995: if (options.password_authentication) {
1.108 markus 996: error("Password authentication is disabled to avoid "
997: "man-in-the-middle attacks.");
1.38 markus 998: options.password_authentication = 0;
1.210 dtucker 999: cancelled_forwarding = 1;
1.144 djm 1000: }
1001: if (options.kbd_interactive_authentication) {
1002: error("Keyboard-interactive authentication is disabled"
1003: " to avoid man-in-the-middle attacks.");
1004: options.kbd_interactive_authentication = 0;
1005: options.challenge_response_authentication = 0;
1.210 dtucker 1006: cancelled_forwarding = 1;
1.144 djm 1007: }
1008: if (options.challenge_response_authentication) {
1009: error("Challenge/response authentication is disabled"
1010: " to avoid man-in-the-middle attacks.");
1011: options.challenge_response_authentication = 0;
1.210 dtucker 1012: cancelled_forwarding = 1;
1.38 markus 1013: }
1014: if (options.forward_agent) {
1.108 markus 1015: error("Agent forwarding is disabled to avoid "
1016: "man-in-the-middle attacks.");
1.38 markus 1017: options.forward_agent = 0;
1.210 dtucker 1018: cancelled_forwarding = 1;
1.83 markus 1019: }
1020: if (options.forward_x11) {
1.108 markus 1021: error("X11 forwarding is disabled to avoid "
1022: "man-in-the-middle attacks.");
1.83 markus 1023: options.forward_x11 = 0;
1.210 dtucker 1024: cancelled_forwarding = 1;
1.83 markus 1025: }
1.108 markus 1026: if (options.num_local_forwards > 0 ||
1027: options.num_remote_forwards > 0) {
1028: error("Port forwarding is disabled to avoid "
1029: "man-in-the-middle attacks.");
1030: options.num_local_forwards =
1.118 deraadt 1031: options.num_remote_forwards = 0;
1.210 dtucker 1032: cancelled_forwarding = 1;
1.194 stevesk 1033: }
1034: if (options.tun_open != SSH_TUNMODE_NO) {
1035: error("Tunnel forwarding is disabled to avoid "
1036: "man-in-the-middle attacks.");
1037: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1038: cancelled_forwarding = 1;
1.339 djm 1039: }
1040: if (options.update_hostkeys != 0) {
1041: error("UpdateHostkeys is disabled because the host "
1042: "key is not trusted.");
1043: options.update_hostkeys = 0;
1.38 markus 1044: }
1.210 dtucker 1045: if (options.exit_on_forward_failure && cancelled_forwarding)
1046: fatal("Error: forwarding disabled due to host key "
1047: "check failure");
1048:
1.40 markus 1049: /*
1050: * XXX Should permit the user to change to use the new id.
1051: * This could be done by converting the host key to an
1052: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1053: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1054: * accept the authentication.
1055: */
1.38 markus 1056: break;
1.132 markus 1057: case HOST_FOUND:
1058: fatal("internal error");
1059: break;
1.88 markus 1060: }
1061:
1062: if (options.check_host_ip && host_status != HOST_CHANGED &&
1063: ip_status == HOST_CHANGED) {
1.119 markus 1064: snprintf(msg, sizeof(msg),
1065: "Warning: the %s host key for '%.200s' "
1066: "differs from the key for the IP address '%.128s'"
1.229 djm 1067: "\nOffending key for IP in %s:%lu",
1068: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1069: if (host_status == HOST_OK) {
1070: len = strlen(msg);
1071: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1072: "\nMatching host key in %s:%lu",
1073: host_found->file, host_found->line);
1.119 markus 1074: }
1.285 djm 1075: if (options.strict_host_key_checking ==
1076: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1077: strlcat(msg, "\nAre you sure you want "
1078: "to continue connecting (yes/no)? ", sizeof(msg));
1.312 dtucker 1079: if (!confirm(msg, NULL))
1.108 markus 1080: goto fail;
1.285 djm 1081: } else if (options.strict_host_key_checking !=
1082: SSH_STRICT_HOSTKEY_OFF) {
1083: logit("%s", msg);
1084: error("Exiting, you have requested strict checking.");
1085: goto fail;
1.119 markus 1086: } else {
1.143 djm 1087: logit("%s", msg);
1.88 markus 1088: }
1.257 djm 1089: }
1090:
1091: if (!hostkey_trusted && options.update_hostkeys) {
1.341 ! djm 1092: debug_f("hostkey not known or explicitly trusted: "
! 1093: "disabling UpdateHostkeys");
1.257 djm 1094: options.update_hostkeys = 0;
1.38 markus 1095: }
1.82 provos 1096:
1.238 djm 1097: free(ip);
1098: free(host);
1.229 djm 1099: if (host_hostkeys != NULL)
1100: free_hostkeys(host_hostkeys);
1101: if (ip_hostkeys != NULL)
1102: free_hostkeys(ip_hostkeys);
1.108 markus 1103: return 0;
1104:
1105: fail:
1.337 djm 1106: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1107: /*
1108: * No matching certificate. Downgrade cert to raw key and
1109: * search normally.
1110: */
1111: debug("No matching CA found. Retry with plain key");
1.280 markus 1112: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1.341 ! djm 1113: fatal_fr(r, "decode key");
1.280 markus 1114: if ((r = sshkey_drop_cert(raw_key)) != 0)
1.341 ! djm 1115: fatal_r(r, "Couldn't drop certificate");
1.219 djm 1116: host_key = raw_key;
1117: goto retry;
1118: }
1.293 dtucker 1119: sshkey_free(raw_key);
1.238 djm 1120: free(ip);
1121: free(host);
1.229 djm 1122: if (host_hostkeys != NULL)
1123: free_hostkeys(host_hostkeys);
1124: if (ip_hostkeys != NULL)
1125: free_hostkeys(ip_hostkeys);
1.108 markus 1126: return -1;
1127: }
1128:
1.337 djm 1129: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1130: int
1.337 djm 1131: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1132: {
1.267 djm 1133: u_int i;
1.337 djm 1134: int r = -1, flags = 0;
1.267 djm 1135: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1136: struct sshkey *plain = NULL;
1.229 djm 1137:
1.252 djm 1138: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1139: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.341 ! djm 1140: error_fr(r, "fingerprint host key");
1.252 djm 1141: r = -1;
1142: goto out;
1143: }
1144:
1.267 djm 1145: if (sshkey_is_cert(host_key)) {
1146: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1147: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.341 ! djm 1148: error_fr(r, "fingerprint CA key");
1.267 djm 1149: r = -1;
1150: goto out;
1151: }
1152: sshkey_format_cert_validity(host_key->cert,
1153: valid, sizeof(valid));
1154: debug("Server host certificate: %s %s, serial %llu "
1155: "ID \"%s\" CA %s %s valid %s",
1156: sshkey_ssh_name(host_key), fp,
1.269 djm 1157: (unsigned long long)host_key->cert->serial,
1158: host_key->cert->key_id,
1.267 djm 1159: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1160: valid);
1161: for (i = 0; i < host_key->cert->nprincipals; i++) {
1162: debug2("Server host certificate hostname: %s",
1163: host_key->cert->principals[i]);
1164: }
1165: } else {
1.276 djm 1166: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1167: }
1.252 djm 1168:
1169: if (sshkey_equal(previous_host_key, host_key)) {
1.341 ! djm 1170: debug2_f("server host key %s %s matches cached key",
! 1171: sshkey_type(host_key), fp);
1.252 djm 1172: r = 0;
1173: goto out;
1174: }
1175:
1176: /* Check in RevokedHostKeys file if specified */
1177: if (options.revoked_host_keys != NULL) {
1178: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1179: switch (r) {
1180: case 0:
1181: break; /* not revoked */
1182: case SSH_ERR_KEY_REVOKED:
1183: error("Host key %s %s revoked by file %s",
1184: sshkey_type(host_key), fp,
1185: options.revoked_host_keys);
1186: r = -1;
1187: goto out;
1188: default:
1.341 ! djm 1189: error_r(r, "Error checking host key %s %s in "
! 1190: "revoked keys file %s", sshkey_type(host_key),
! 1191: fp, options.revoked_host_keys);
1.252 djm 1192: r = -1;
1193: goto out;
1194: }
1.250 djm 1195: }
1196:
1.247 djm 1197: if (options.verify_host_key_dns) {
1198: /*
1199: * XXX certs are not yet supported for DNS, so downgrade
1200: * them and try the plain key.
1201: */
1.252 djm 1202: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1203: goto out;
1204: if (sshkey_is_cert(plain))
1205: sshkey_drop_cert(plain);
1.247 djm 1206: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1207: if (flags & DNS_VERIFY_FOUND) {
1208: if (options.verify_host_key_dns == 1 &&
1209: flags & DNS_VERIFY_MATCH &&
1210: flags & DNS_VERIFY_SECURE) {
1.250 djm 1211: r = 0;
1.252 djm 1212: goto out;
1.247 djm 1213: }
1214: if (flags & DNS_VERIFY_MATCH) {
1215: matching_host_key_dns = 1;
1216: } else {
1.287 djm 1217: warn_changed_key(plain);
1218: error("Update the SSHFP RR in DNS "
1219: "with the new host key to get rid "
1220: "of this message.");
1.247 djm 1221: }
1.153 jakob 1222: }
1.140 jakob 1223: }
1224: }
1.250 djm 1225: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1226: options.user_hostfiles, options.num_user_hostfiles,
1.337 djm 1227: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1228:
1.252 djm 1229: out:
1230: sshkey_free(plain);
1231: free(fp);
1.267 djm 1232: free(cafp);
1.337 djm 1233: if (r == 0 && host_key != NULL) {
1234: sshkey_free(previous_host_key);
1235: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1236: }
1237:
1238: return r;
1.51 markus 1239: }
1.70 markus 1240:
1.51 markus 1241: /*
1242: * Starts a dialog with the server, and authenticates the current user on the
1243: * server. This does not need any extra privileges. The basic connection
1244: * to the server must already have been established before this is called.
1245: * If login fails, this function prints an error and never returns.
1246: * This function does not require super-user privileges.
1247: */
1248: void
1.309 djm 1249: ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost,
1.229 djm 1250: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1251: {
1.241 djm 1252: char *host;
1.70 markus 1253: char *server_user, *local_user;
1.329 djm 1254: int r;
1.70 markus 1255:
1256: local_user = xstrdup(pw->pw_name);
1257: server_user = options.user ? options.user : local_user;
1.51 markus 1258:
1259: /* Convert the user-supplied hostname into all lowercase. */
1260: host = xstrdup(orighost);
1.241 djm 1261: lowercase(host);
1.51 markus 1262:
1263: /* Exchange protocol version identification strings with the server. */
1.329 djm 1264: if ((r = kex_exchange_identification(ssh, timeout_ms, NULL)) != 0)
1265: sshpkt_fatal(ssh, r, "banner exchange");
1.51 markus 1266:
1267: /* Put the connection into non-blocking mode. */
1.309 djm 1268: ssh_packet_set_nonblocking(ssh);
1.51 markus 1269:
1270: /* key exchange */
1271: /* authenticate user */
1.261 dtucker 1272: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.309 djm 1273: ssh_kex2(ssh, host, hostaddr, port);
1274: ssh_userauth2(ssh, local_user, server_user, host, sensitive);
1.238 djm 1275: free(local_user);
1.315 dtucker 1276: free(host);
1.132 markus 1277: }
1278:
1279: /* print all known host keys for a given host, but skip keys of given type */
1280: static int
1.279 markus 1281: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1282: {
1.242 djm 1283: int type[] = {
1284: KEY_RSA,
1285: KEY_DSA,
1286: KEY_ECDSA,
1287: KEY_ED25519,
1.297 markus 1288: KEY_XMSS,
1.242 djm 1289: -1
1290: };
1.229 djm 1291: int i, ret = 0;
1292: char *fp, *ra;
1293: const struct hostkey_entry *found;
1.132 markus 1294:
1295: for (i = 0; type[i] != -1; i++) {
1296: if (type[i] == key->type)
1297: continue;
1.335 djm 1298: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i],
1299: -1, &found))
1.132 markus 1300: continue;
1.259 djm 1301: fp = sshkey_fingerprint(found->key,
1.254 djm 1302: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1303: ra = sshkey_fingerprint(found->key,
1.254 djm 1304: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1305: if (fp == NULL || ra == NULL)
1.341 ! djm 1306: fatal_f("sshkey_fingerprint fail");
1.229 djm 1307: logit("WARNING: %s key found for host %s\n"
1308: "in %s:%lu\n"
1309: "%s key fingerprint %s.",
1.300 markus 1310: sshkey_type(found->key),
1.229 djm 1311: found->host, found->file, found->line,
1.300 markus 1312: sshkey_type(found->key), fp);
1.229 djm 1313: if (options.visual_host_key)
1314: logit("%s", ra);
1.238 djm 1315: free(ra);
1316: free(fp);
1.229 djm 1317: ret = 1;
1.132 markus 1318: }
1.229 djm 1319: return ret;
1.150 jakob 1320: }
1321:
1322: static void
1.279 markus 1323: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1324: {
1325: char *fp;
1326:
1.259 djm 1327: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1328: SSH_FP_DEFAULT);
1.259 djm 1329: if (fp == NULL)
1.341 ! djm 1330: fatal_f("sshkey_fingerprint fail");
1.150 jakob 1331:
1332: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1333: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1334: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1335: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1336: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1337: error("It is also possible that a host key has just been changed.");
1.150 jakob 1338: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.300 markus 1339: sshkey_type(host_key), fp);
1.150 jakob 1340: error("Please contact your system administrator.");
1341:
1.238 djm 1342: free(fp);
1.171 reyk 1343: }
1344:
1345: /*
1346: * Execute a local command
1347: */
1348: int
1349: ssh_local_cmd(const char *args)
1350: {
1351: char *shell;
1352: pid_t pid;
1353: int status;
1.231 djm 1354: void (*osighand)(int);
1.171 reyk 1355:
1356: if (!options.permit_local_command ||
1357: args == NULL || !*args)
1358: return (1);
1359:
1.226 djm 1360: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1361: shell = _PATH_BSHELL;
1362:
1.327 dtucker 1363: osighand = ssh_signal(SIGCHLD, SIG_DFL);
1.171 reyk 1364: pid = fork();
1365: if (pid == 0) {
1.327 dtucker 1366: ssh_signal(SIGPIPE, SIG_DFL);
1.171 reyk 1367: debug3("Executing %s -c \"%s\"", shell, args);
1368: execl(shell, shell, "-c", args, (char *)NULL);
1369: error("Couldn't execute %s -c \"%s\": %s",
1370: shell, args, strerror(errno));
1371: _exit(1);
1372: } else if (pid == -1)
1373: fatal("fork failed: %.100s", strerror(errno));
1374: while (waitpid(pid, &status, 0) == -1)
1375: if (errno != EINTR)
1376: fatal("Couldn't wait for child: %s", strerror(errno));
1.327 dtucker 1377: ssh_signal(SIGCHLD, osighand);
1.171 reyk 1378:
1379: if (!WIFEXITED(status))
1380: return (1);
1381:
1382: return (WEXITSTATUS(status));
1.266 jcs 1383: }
1384:
1385: void
1.328 djm 1386: maybe_add_key_to_agent(const char *authfile, struct sshkey *private,
1387: const char *comment, const char *passphrase)
1.266 jcs 1388: {
1389: int auth_sock = -1, r;
1.321 djm 1390: const char *skprovider = NULL;
1.266 jcs 1391:
1392: if (options.add_keys_to_agent == 0)
1393: return;
1394:
1395: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1396: debug3("no authentication agent, not adding key");
1397: return;
1398: }
1399:
1400: if (options.add_keys_to_agent == 2 &&
1401: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1402: debug3("user denied adding this key");
1.273 dtucker 1403: close(auth_sock);
1.266 jcs 1404: return;
1405: }
1.322 markus 1406: if (sshkey_is_sk(private))
1.321 djm 1407: skprovider = options.sk_provider;
1.328 djm 1408: if ((r = ssh_add_identity_constrained(auth_sock, private,
1.331 djm 1409: comment == NULL ? authfile : comment,
1410: options.add_keys_to_agent_lifespan,
1.321 djm 1411: (options.add_keys_to_agent == 3), 0, skprovider)) == 0)
1.266 jcs 1412: debug("identity added to agent: %s", authfile);
1413: else
1414: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1415: close(auth_sock);
1.1 deraadt 1416: }