Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.343
1.343 ! dtucker 1: /* $OpenBSD: sshconnect.c,v 1.342 2020/11/12 22:56:00 djm Exp $ */
1.1 deraadt 2: /*
1.39 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
1.78 deraadt 8: *
9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 14: */
1.1 deraadt 15:
1.174 stevesk 16: #include <sys/types.h>
17: #include <sys/wait.h>
1.175 stevesk 18: #include <sys/stat.h>
1.187 stevesk 19: #include <sys/socket.h>
1.195 stevesk 20: #include <sys/time.h>
1.187 stevesk 21:
1.295 djm 22: #include <net/if.h>
1.187 stevesk 23: #include <netinet/in.h>
1.172 stevesk 24:
1.176 stevesk 25: #include <ctype.h>
1.190 stevesk 26: #include <errno.h>
1.216 dtucker 27: #include <fcntl.h>
1.191 stevesk 28: #include <netdb.h>
1.172 stevesk 29: #include <paths.h>
1.199 deraadt 30: #include <signal.h>
1.188 stevesk 31: #include <pwd.h>
1.198 stevesk 32: #include <stdio.h>
1.196 stevesk 33: #include <stdlib.h>
1.323 deraadt 34: #include <stdarg.h>
1.193 stevesk 35: #include <string.h>
1.192 stevesk 36: #include <unistd.h>
1.295 djm 37: #include <ifaddrs.h>
1.71 markus 38:
1.199 deraadt 39: #include "xmalloc.h"
1.91 markus 40: #include "ssh.h"
1.299 markus 41: #include "sshbuf.h"
1.1 deraadt 42: #include "packet.h"
1.21 markus 43: #include "compat.h"
1.300 markus 44: #include "sshkey.h"
1.71 markus 45: #include "sshconnect.h"
1.58 markus 46: #include "hostfile.h"
1.91 markus 47: #include "log.h"
1.251 millert 48: #include "misc.h"
1.91 markus 49: #include "readconf.h"
50: #include "atomicio.h"
1.140 jakob 51: #include "dns.h"
1.239 djm 52: #include "monitor_fdpass.h"
1.219 djm 53: #include "ssh2.h"
1.186 stevesk 54: #include "version.h"
1.252 djm 55: #include "authfile.h"
56: #include "ssherr.h"
1.266 jcs 57: #include "authfd.h"
1.309 djm 58: #include "kex.h"
1.310 djm 59:
1.279 markus 60: struct sshkey *previous_host_key = NULL;
1.59 markus 61:
1.169 stevesk 62: static int matching_host_key_dns = 0;
1.145 jakob 63:
1.227 djm 64: static pid_t proxy_command_pid = 0;
65:
1.124 markus 66: /* import */
1.307 djm 67: extern int debug_flag;
1.43 markus 68: extern Options options;
1.50 markus 69: extern char *__progname;
1.91 markus 70:
1.279 markus 71: static int show_other_keys(struct hostkeys *, struct sshkey *);
72: static void warn_changed_key(struct sshkey *);
1.132 markus 73:
1.239 djm 74: /* Expand a proxy command */
75: static char *
76: expand_proxy_command(const char *proxy_command, const char *user,
1.325 naddy 77: const char *host, const char *host_arg, int port)
1.239 djm 78: {
79: char *tmp, *ret, strport[NI_MAXSERV];
1.330 dtucker 80: const char *keyalias = options.host_key_alias ?
81: options.host_key_alias : host_arg;
1.239 djm 82:
1.241 djm 83: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 84: xasprintf(&tmp, "exec %s", proxy_command);
1.318 djm 85: ret = percent_expand(tmp,
86: "h", host,
1.330 dtucker 87: "k", keyalias,
1.318 djm 88: "n", host_arg,
89: "p", strport,
90: "r", options.user,
91: (char *)NULL);
1.239 djm 92: free(tmp);
93: return ret;
94: }
95:
96: /*
97: * Connect to the given ssh server using a proxy command that passes a
98: * a connected fd back to us.
99: */
100: static int
1.318 djm 101: ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host,
102: const char *host_arg, u_short port, const char *proxy_command)
1.239 djm 103: {
104: char *command_string;
105: int sp[2], sock;
106: pid_t pid;
107: char *shell;
108:
109: if ((shell = getenv("SHELL")) == NULL)
110: shell = _PATH_BSHELL;
111:
1.317 deraadt 112: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) == -1)
1.239 djm 113: fatal("Could not create socketpair to communicate with "
114: "proxy dialer: %.100s", strerror(errno));
115:
116: command_string = expand_proxy_command(proxy_command, options.user,
1.325 naddy 117: host, host_arg, port);
1.239 djm 118: debug("Executing proxy dialer command: %.500s", command_string);
119:
120: /* Fork and execute the proxy command. */
121: if ((pid = fork()) == 0) {
122: char *argv[10];
123:
124: close(sp[1]);
125: /* Redirect stdin and stdout. */
126: if (sp[0] != 0) {
1.317 deraadt 127: if (dup2(sp[0], 0) == -1)
1.239 djm 128: perror("dup2 stdin");
129: }
130: if (sp[0] != 1) {
1.317 deraadt 131: if (dup2(sp[0], 1) == -1)
1.239 djm 132: perror("dup2 stdout");
133: }
134: if (sp[0] >= 2)
135: close(sp[0]);
136:
137: /*
1.307 djm 138: * Stderr is left for non-ControlPersist connections is so
139: * error messages may be printed on the user's terminal.
1.239 djm 140: */
1.308 dtucker 141: if (!debug_flag && options.control_path != NULL &&
1.334 djm 142: options.control_persist && stdfd_devnull(0, 0, 1) == -1)
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:
1.342 djm 665: struct find_by_key_ctx {
666: const char *host, *ip;
667: const struct sshkey *key;
668: char **names;
669: u_int nnames;
670: };
671:
672: /* Try to replace home directory prefix (per $HOME) with a ~/ sequence */
673: static char *
674: try_tilde_unexpand(const char *path)
675: {
676: char *home, *ret = NULL;
677: size_t l;
678:
679: if (*path != '/')
680: return xstrdup(path);
681: if ((home = getenv("HOME")) == NULL || (l = strlen(home)) == 0)
682: return xstrdup(path);
683: if (strncmp(path, home, l) != 0)
684: return xstrdup(path);
685: /*
686: * ensure we have matched on a path boundary: either the $HOME that
687: * we just compared ends with a '/' or the next character of the path
688: * must be a '/'.
689: */
690: if (home[l - 1] != '/' && path[l] != '/')
691: return xstrdup(path);
692: if (path[l] == '/')
693: l++;
694: xasprintf(&ret, "~/%s", path + l);
695: return ret;
696: }
697:
698: static int
699: hostkeys_find_by_key_cb(struct hostkey_foreach_line *l, void *_ctx)
700: {
701: struct find_by_key_ctx *ctx = (struct find_by_key_ctx *)_ctx;
702: char *path;
703:
704: /* we are looking for keys with names that *do not* match */
705: if ((l->match & HKF_MATCH_HOST) != 0)
706: return 0;
707: /* not interested in marker lines */
708: if (l->marker != MRK_NONE)
709: return 0;
710: /* we are only interested in exact key matches */
711: if (l->key == NULL || !sshkey_equal(ctx->key, l->key))
712: return 0;
713: path = try_tilde_unexpand(l->path);
714: debug_f("found matching key in %s:%lu", path, l->linenum);
715: ctx->names = xrecallocarray(ctx->names,
716: ctx->nnames, ctx->nnames + 1, sizeof(*ctx->names));
717: xasprintf(&ctx->names[ctx->nnames], "%s:%lu: %s", path, l->linenum,
718: strncmp(l->hosts, HASH_MAGIC, strlen(HASH_MAGIC)) == 0 ?
719: "[hashed name]" : l->hosts);
720: ctx->nnames++;
721: free(path);
722: return 0;
723: }
724:
725: static int
726: hostkeys_find_by_key_hostfile(const char *file, const char *which,
727: struct find_by_key_ctx *ctx)
728: {
729: int r;
730:
731: debug3_f("trying %s hostfile \"%s\"", which, file);
732: if ((r = hostkeys_foreach(file, hostkeys_find_by_key_cb, ctx,
733: ctx->host, ctx->ip, HKF_WANT_PARSE_KEY)) != 0) {
734: if (r == SSH_ERR_SYSTEM_ERROR && errno == ENOENT) {
735: debug_f("hostkeys file %s does not exist", file);
736: return 0;
737: }
738: error_fr(r, "hostkeys_foreach failed for %s", file);
739: return r;
740: }
741: return 0;
742: }
743:
744: /*
745: * Find 'key' in known hosts file(s) that do not match host/ip.
746: * Used to display also-known-as information for previously-unseen hostkeys.
747: */
748: static void
749: hostkeys_find_by_key(const char *host, const char *ip, const struct sshkey *key,
750: char **user_hostfiles, u_int num_user_hostfiles,
751: char **system_hostfiles, u_int num_system_hostfiles,
752: char ***names, u_int *nnames)
753: {
1.343 ! dtucker 754: struct find_by_key_ctx ctx = {0, 0, 0, 0, 0};
1.342 djm 755: u_int i;
756:
757: *names = NULL;
758: *nnames = 0;
759:
760: if (key == NULL || sshkey_is_cert(key))
761: return;
762:
763: ctx.host = host;
764: ctx.ip = ip;
765: ctx.key = key;
766:
767: for (i = 0; i < num_user_hostfiles; i++) {
768: if (hostkeys_find_by_key_hostfile(user_hostfiles[i],
769: "user", &ctx) != 0)
770: goto fail;
771: }
772: for (i = 0; i < num_system_hostfiles; i++) {
773: if (hostkeys_find_by_key_hostfile(system_hostfiles[i],
774: "system", &ctx) != 0)
775: goto fail;
776: }
777: /* success */
778: *names = ctx.names;
779: *nnames = ctx.nnames;
780: ctx.names = NULL;
781: ctx.nnames = 0;
782: return;
783: fail:
784: for (i = 0; i < ctx.nnames; i++)
785: free(ctx.names[i]);
786: free(ctx.names);
787: }
788:
789: #define MAX_OTHER_NAMES 8 /* Maximum number of names to list */
790: static char *
791: other_hostkeys_message(const char *host, const char *ip,
792: const struct sshkey *key,
793: char **user_hostfiles, u_int num_user_hostfiles,
794: char **system_hostfiles, u_int num_system_hostfiles)
795: {
796: char *ret = NULL, **othernames = NULL;
797: u_int i, n, num_othernames = 0;
798:
799: hostkeys_find_by_key(host, ip, key,
800: user_hostfiles, num_user_hostfiles,
801: system_hostfiles, num_system_hostfiles,
802: &othernames, &num_othernames);
803: if (num_othernames == 0)
804: return xstrdup("This key is not known by any other names");
805:
806: xasprintf(&ret, "This host key is known by the following other "
807: "names/addresses:");
808:
809: n = num_othernames;
810: if (n > MAX_OTHER_NAMES)
811: n = MAX_OTHER_NAMES;
812: for (i = 0; i < n; i++) {
813: xextendf(&ret, "\n", " %s", othernames[i]);
814: }
815: if (n < num_othernames) {
816: xextendf(&ret, "\n", " (%d additional names ommitted)",
817: num_othernames - n);
818: }
819: for (i = 0; i < num_othernames; i++)
820: free(othernames[i]);
821: free(othernames);
822: return ret;
823: }
824:
1.39 deraadt 825: /*
1.108 markus 826: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 827: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 828: */
1.197 dtucker 829: #define RDRW 0
830: #define RDONLY 1
831: #define ROQUIET 2
1.109 itojun 832: static int
1.197 dtucker 833: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 834: struct sshkey *host_key, int readonly,
1.234 djm 835: char **user_hostfiles, u_int num_user_hostfiles,
1.337 djm 836: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 837: {
1.338 djm 838: HostStatus host_status = -1, ip_status = -1;
1.279 markus 839: struct sshkey *raw_key = NULL;
1.189 dtucker 840: char *ip = NULL, *host = NULL;
1.204 grunk 841: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 842: char msg[1024];
1.234 djm 843: const char *type;
1.338 djm 844: const struct hostkey_entry *host_found = NULL, *ip_found = NULL;
1.312 dtucker 845: int len, cancelled_forwarding = 0, confirmed;
1.337 djm 846: int local = sockaddr_is_local(hostaddr);
1.280 markus 847: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 848: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 849: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 850: u_int i;
1.49 markus 851:
852: /*
853: * Force accepting of the host key for loopback/localhost. The
854: * problem is that if the home directory is NFS-mounted to multiple
855: * machines, localhost will refer to a different machine in each of
856: * them, and the user will get bogus HOST_CHANGED warnings. This
857: * essentially disables host authentication for localhost; however,
858: * this is probably not a real problem.
859: */
1.111 markus 860: if (options.no_host_authentication_for_localhost == 1 && local &&
861: options.host_key_alias == NULL) {
1.88 markus 862: debug("Forcing accepting of host key for "
863: "loopback/localhost.");
1.338 djm 864: options.update_hostkeys = 0;
1.108 markus 865: return 0;
1.49 markus 866: }
1.42 markus 867:
868: /*
1.229 djm 869: * Prepare the hostname and address strings used for hostkey lookup.
870: * In some cases, these will have a port number appended.
1.42 markus 871: */
1.229 djm 872: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 873:
874: /*
1.88 markus 875: * Turn off check_host_ip if the connection is to localhost, via proxy
876: * command or if we don't have a hostname to compare with
877: */
1.189 dtucker 878: if (options.check_host_ip && (local ||
879: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 880: options.check_host_ip = 0;
1.86 markus 881:
1.229 djm 882: host_hostkeys = init_hostkeys();
1.234 djm 883: for (i = 0; i < num_user_hostfiles; i++)
884: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
885: for (i = 0; i < num_system_hostfiles; i++)
886: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 887:
888: ip_hostkeys = NULL;
889: if (!want_cert && options.check_host_ip) {
890: ip_hostkeys = init_hostkeys();
1.234 djm 891: for (i = 0; i < num_user_hostfiles; i++)
892: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
893: for (i = 0; i < num_system_hostfiles; i++)
894: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 895: }
1.38 markus 896:
1.219 djm 897: retry:
1.229 djm 898: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 899: want_cert = sshkey_is_cert(host_key);
900: type = sshkey_type(host_key);
1.219 djm 901:
1.46 markus 902: /*
1.170 djm 903: * Check if the host key is present in the user's list of known
1.40 markus 904: * hosts or in the systemwide list.
905: */
1.229 djm 906: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
907: &host_found);
908:
1.40 markus 909: /*
910: * Also perform check for the ip address, skip the check if we are
1.219 djm 911: * localhost, looking for a certificate, or the hostname was an ip
912: * address to begin with.
1.40 markus 913: */
1.229 djm 914: if (!want_cert && ip_hostkeys != NULL) {
915: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
916: &ip_found);
1.38 markus 917: if (host_status == HOST_CHANGED &&
1.319 djm 918: (ip_status != HOST_CHANGED ||
1.229 djm 919: (ip_found != NULL &&
1.280 markus 920: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 921: host_ip_differ = 1;
922: } else
923: ip_status = host_status;
924:
925: switch (host_status) {
926: case HOST_OK:
927: /* The host is known and the key matches. */
1.219 djm 928: debug("Host '%.200s' is known and matches the %s host %s.",
929: host, type, want_cert ? "certificate" : "key");
1.229 djm 930: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
931: host_found->file, host_found->line);
1.281 djm 932: if (want_cert &&
933: !check_host_cert(options.host_key_alias == NULL ?
934: hostname : options.host_key_alias, host_key))
1.219 djm 935: goto fail;
1.338 djm 936: /* Turn off UpdateHostkeys if key was in system known_hosts */
937: if (options.update_hostkeys != 0 &&
938: (path_in_hostfiles(host_found->file,
939: system_hostfiles, num_system_hostfiles) ||
940: (ip_status == HOST_OK && ip_found != NULL &&
941: path_in_hostfiles(ip_found->file,
942: system_hostfiles, num_system_hostfiles)))) {
943: options.update_hostkeys = 0;
1.341 djm 944: debug3_f("host key found in GlobalKnownHostsFile; "
945: "disabling UpdateHostkeys");
1.338 djm 946: }
1.88 markus 947: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 948: if (readonly || want_cert)
1.138 itojun 949: logit("%s host key for IP address "
1.108 markus 950: "'%.128s' not in list of known hosts.",
951: type, ip);
1.234 djm 952: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 953: host_key, options.hash_known_hosts))
1.138 itojun 954: logit("Failed to add the %s host key for IP "
1.108 markus 955: "address '%.128s' to the list of known "
1.262 dtucker 956: "hosts (%.500s).", type, ip,
1.234 djm 957: user_hostfiles[0]);
1.88 markus 958: else
1.138 itojun 959: logit("Warning: Permanently added the %s host "
1.108 markus 960: "key for IP address '%.128s' to the list "
961: "of known hosts.", type, ip);
1.209 grunk 962: } else if (options.visual_host_key) {
1.259 djm 963: fp = sshkey_fingerprint(host_key,
1.254 djm 964: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 965: ra = sshkey_fingerprint(host_key,
1.254 djm 966: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 967: if (fp == NULL || ra == NULL)
1.341 djm 968: fatal_f("sshkey_fingerprint failed");
1.264 djm 969: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 970: free(ra);
971: free(fp);
1.38 markus 972: }
1.257 djm 973: hostkey_trusted = 1;
1.38 markus 974: break;
975: case HOST_NEW:
1.197 dtucker 976: if (options.host_key_alias == NULL && port != 0 &&
977: port != SSH_DEFAULT_PORT) {
978: debug("checking without port identifier");
1.212 stevesk 979: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 980: ROQUIET, user_hostfiles, num_user_hostfiles,
1.337 djm 981: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 982: debug("found matching key w/out port");
983: break;
984: }
985: }
1.219 djm 986: if (readonly || want_cert)
1.108 markus 987: goto fail;
1.38 markus 988: /* The host is new. */
1.285 djm 989: if (options.strict_host_key_checking ==
990: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 991: /*
992: * User has requested strict host key checking. We
993: * will not add the host key automatically. The only
994: * alternative left is to abort.
995: */
996: error("No %s host key is known for %.200s and you "
997: "have requested strict checking.", type, host);
998: goto fail;
1.285 djm 999: } else if (options.strict_host_key_checking ==
1000: SSH_STRICT_HOSTKEY_ASK) {
1.342 djm 1001: char *msg1 = NULL, *msg2 = NULL;
1002:
1003: xasprintf(&msg1, "The authenticity of host "
1004: "'%.200s (%s)' can't be established", host, ip);
1005:
1006: if (show_other_keys(host_hostkeys, host_key)) {
1007: xextendf(&msg1, "\n", "but keys of different "
1008: "type are already known for this host.");
1009: } else
1010: xextendf(&msg1, "", ".");
1.145 jakob 1011:
1.259 djm 1012: fp = sshkey_fingerprint(host_key,
1.254 djm 1013: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1014: ra = sshkey_fingerprint(host_key,
1.254 djm 1015: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1016: if (fp == NULL || ra == NULL)
1.341 djm 1017: fatal_f("sshkey_fingerprint failed");
1.342 djm 1018: xextendf(&msg1, "\n", "%s key fingerprint is %s.",
1019: type, fp);
1020: if (options.visual_host_key)
1021: xextendf(&msg1, "\n", "%s", ra);
1.145 jakob 1022: if (options.verify_host_key_dns) {
1.342 djm 1023: xextendf(&msg1, "\n",
1024: "%s host key fingerprint found in DNS.",
1025: matching_host_key_dns ?
1026: "Matching" : "No matching");
1.145 jakob 1027: }
1.342 djm 1028: /* msg2 informs for other names matching this key */
1029: if ((msg2 = other_hostkeys_message(host, ip, host_key,
1030: user_hostfiles, num_user_hostfiles,
1031: system_hostfiles, num_system_hostfiles)) != NULL)
1032: xextendf(&msg1, "\n", "%s", msg2);
1033:
1034: xextendf(&msg1, "\n",
1.108 markus 1035: "Are you sure you want to continue connecting "
1.342 djm 1036: "(yes/no/[fingerprint])? ");
1037:
1038: confirmed = confirm(msg1, fp);
1.238 djm 1039: free(ra);
1040: free(fp);
1.342 djm 1041: free(msg1);
1042: free(msg2);
1.312 dtucker 1043: if (!confirmed)
1.108 markus 1044: goto fail;
1.257 djm 1045: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 1046: }
1.161 djm 1047: /*
1.285 djm 1048: * If in "new" or "off" strict mode, add the key automatically
1049: * to the local known_hosts file.
1.161 djm 1050: */
1.88 markus 1051: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 1052: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 1053: hostp = hostline;
1.161 djm 1054: if (options.hash_known_hosts) {
1055: /* Add hash of host and IP separately */
1.234 djm 1056: r = add_host_to_hostfile(user_hostfiles[0],
1057: host, host_key, options.hash_known_hosts) &&
1058: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 1059: host_key, options.hash_known_hosts);
1060: } else {
1061: /* Add unhashed "host,ip" */
1.234 djm 1062: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 1063: hostline, host_key,
1064: options.hash_known_hosts);
1065: }
1066: } else {
1.234 djm 1067: r = add_host_to_hostfile(user_hostfiles[0], host,
1068: host_key, options.hash_known_hosts);
1.38 markus 1069: hostp = host;
1.161 djm 1070: }
1.38 markus 1071:
1.161 djm 1072: if (!r)
1.138 itojun 1073: logit("Failed to add the host to the list of known "
1.234 djm 1074: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 1075: else
1.138 itojun 1076: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 1077: "list of known hosts.", hostp, type);
1.38 markus 1078: break;
1.220 djm 1079: case HOST_REVOKED:
1080: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1081: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
1082: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1083: error("The %s host key for %s is marked as revoked.", type, host);
1084: error("This could mean that a stolen key is being used to");
1085: error("impersonate this host.");
1086:
1087: /*
1088: * If strict host key checking is in use, the user will have
1089: * to edit the key manually and we can only abort.
1090: */
1.285 djm 1091: if (options.strict_host_key_checking !=
1092: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 1093: error("%s host key for %.200s was revoked and you have "
1094: "requested strict checking.", type, host);
1095: goto fail;
1096: }
1097: goto continue_unsafe;
1098:
1.38 markus 1099: case HOST_CHANGED:
1.219 djm 1100: if (want_cert) {
1101: /*
1102: * This is only a debug() since it is valid to have
1103: * CAs with wildcard DNS matches that don't match
1104: * all hosts that one might visit.
1105: */
1106: debug("Host certificate authority does not "
1.229 djm 1107: "match %s in %s:%lu", CA_MARKER,
1108: host_found->file, host_found->line);
1.219 djm 1109: goto fail;
1110: }
1.197 dtucker 1111: if (readonly == ROQUIET)
1112: goto fail;
1.38 markus 1113: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1114: char *key_msg;
1.38 markus 1115: if (ip_status == HOST_NEW)
1.158 avsm 1116: key_msg = "is unknown";
1.38 markus 1117: else if (ip_status == HOST_OK)
1.158 avsm 1118: key_msg = "is unchanged";
1.38 markus 1119: else
1.158 avsm 1120: key_msg = "has a different value";
1.38 markus 1121: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1122: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1123: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1124: error("The %s host key for %s has changed,", type, host);
1.208 ian 1125: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1126: error("%s. This could either mean that", key_msg);
1.38 markus 1127: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1128: error("and its host key have changed at the same time.");
1.88 markus 1129: if (ip_status != HOST_NEW)
1.229 djm 1130: error("Offending key for IP in %s:%lu",
1131: ip_found->file, ip_found->line);
1.38 markus 1132: }
1133: /* The host key has changed. */
1.150 jakob 1134: warn_changed_key(host_key);
1.38 markus 1135: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1136: user_hostfiles[0]);
1.280 markus 1137: error("Offending %s key in %s:%lu",
1138: sshkey_type(host_found->key),
1.229 djm 1139: host_found->file, host_found->line);
1.38 markus 1140:
1.40 markus 1141: /*
1142: * If strict host key checking is in use, the user will have
1143: * to edit the key manually and we can only abort.
1144: */
1.285 djm 1145: if (options.strict_host_key_checking !=
1146: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 1147: error("%s host key for %.200s has changed and you have "
1148: "requested strict checking.", type, host);
1149: goto fail;
1150: }
1.38 markus 1151:
1.220 djm 1152: continue_unsafe:
1.40 markus 1153: /*
1154: * If strict host key checking has not been requested, allow
1.144 djm 1155: * the connection but without MITM-able authentication or
1.194 stevesk 1156: * forwarding.
1.40 markus 1157: */
1.38 markus 1158: if (options.password_authentication) {
1.108 markus 1159: error("Password authentication is disabled to avoid "
1160: "man-in-the-middle attacks.");
1.38 markus 1161: options.password_authentication = 0;
1.210 dtucker 1162: cancelled_forwarding = 1;
1.144 djm 1163: }
1164: if (options.kbd_interactive_authentication) {
1165: error("Keyboard-interactive authentication is disabled"
1166: " to avoid man-in-the-middle attacks.");
1167: options.kbd_interactive_authentication = 0;
1168: options.challenge_response_authentication = 0;
1.210 dtucker 1169: cancelled_forwarding = 1;
1.144 djm 1170: }
1171: if (options.challenge_response_authentication) {
1172: error("Challenge/response authentication is disabled"
1173: " to avoid man-in-the-middle attacks.");
1174: options.challenge_response_authentication = 0;
1.210 dtucker 1175: cancelled_forwarding = 1;
1.38 markus 1176: }
1177: if (options.forward_agent) {
1.108 markus 1178: error("Agent forwarding is disabled to avoid "
1179: "man-in-the-middle attacks.");
1.38 markus 1180: options.forward_agent = 0;
1.210 dtucker 1181: cancelled_forwarding = 1;
1.83 markus 1182: }
1183: if (options.forward_x11) {
1.108 markus 1184: error("X11 forwarding is disabled to avoid "
1185: "man-in-the-middle attacks.");
1.83 markus 1186: options.forward_x11 = 0;
1.210 dtucker 1187: cancelled_forwarding = 1;
1.83 markus 1188: }
1.108 markus 1189: if (options.num_local_forwards > 0 ||
1190: options.num_remote_forwards > 0) {
1191: error("Port forwarding is disabled to avoid "
1192: "man-in-the-middle attacks.");
1193: options.num_local_forwards =
1.118 deraadt 1194: options.num_remote_forwards = 0;
1.210 dtucker 1195: cancelled_forwarding = 1;
1.194 stevesk 1196: }
1197: if (options.tun_open != SSH_TUNMODE_NO) {
1198: error("Tunnel forwarding is disabled to avoid "
1199: "man-in-the-middle attacks.");
1200: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1201: cancelled_forwarding = 1;
1.339 djm 1202: }
1203: if (options.update_hostkeys != 0) {
1204: error("UpdateHostkeys is disabled because the host "
1205: "key is not trusted.");
1206: options.update_hostkeys = 0;
1.38 markus 1207: }
1.210 dtucker 1208: if (options.exit_on_forward_failure && cancelled_forwarding)
1209: fatal("Error: forwarding disabled due to host key "
1210: "check failure");
1211:
1.40 markus 1212: /*
1213: * XXX Should permit the user to change to use the new id.
1214: * This could be done by converting the host key to an
1215: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1216: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1217: * accept the authentication.
1218: */
1.38 markus 1219: break;
1.132 markus 1220: case HOST_FOUND:
1221: fatal("internal error");
1222: break;
1.88 markus 1223: }
1224:
1225: if (options.check_host_ip && host_status != HOST_CHANGED &&
1226: ip_status == HOST_CHANGED) {
1.119 markus 1227: snprintf(msg, sizeof(msg),
1228: "Warning: the %s host key for '%.200s' "
1229: "differs from the key for the IP address '%.128s'"
1.229 djm 1230: "\nOffending key for IP in %s:%lu",
1231: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1232: if (host_status == HOST_OK) {
1233: len = strlen(msg);
1234: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1235: "\nMatching host key in %s:%lu",
1236: host_found->file, host_found->line);
1.119 markus 1237: }
1.285 djm 1238: if (options.strict_host_key_checking ==
1239: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1240: strlcat(msg, "\nAre you sure you want "
1241: "to continue connecting (yes/no)? ", sizeof(msg));
1.312 dtucker 1242: if (!confirm(msg, NULL))
1.108 markus 1243: goto fail;
1.285 djm 1244: } else if (options.strict_host_key_checking !=
1245: SSH_STRICT_HOSTKEY_OFF) {
1246: logit("%s", msg);
1247: error("Exiting, you have requested strict checking.");
1248: goto fail;
1.119 markus 1249: } else {
1.143 djm 1250: logit("%s", msg);
1.88 markus 1251: }
1.257 djm 1252: }
1253:
1254: if (!hostkey_trusted && options.update_hostkeys) {
1.341 djm 1255: debug_f("hostkey not known or explicitly trusted: "
1256: "disabling UpdateHostkeys");
1.257 djm 1257: options.update_hostkeys = 0;
1.38 markus 1258: }
1.82 provos 1259:
1.238 djm 1260: free(ip);
1261: free(host);
1.229 djm 1262: if (host_hostkeys != NULL)
1263: free_hostkeys(host_hostkeys);
1264: if (ip_hostkeys != NULL)
1265: free_hostkeys(ip_hostkeys);
1.108 markus 1266: return 0;
1267:
1268: fail:
1.337 djm 1269: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1270: /*
1271: * No matching certificate. Downgrade cert to raw key and
1272: * search normally.
1273: */
1274: debug("No matching CA found. Retry with plain key");
1.280 markus 1275: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1.341 djm 1276: fatal_fr(r, "decode key");
1.280 markus 1277: if ((r = sshkey_drop_cert(raw_key)) != 0)
1.341 djm 1278: fatal_r(r, "Couldn't drop certificate");
1.219 djm 1279: host_key = raw_key;
1280: goto retry;
1281: }
1.293 dtucker 1282: sshkey_free(raw_key);
1.238 djm 1283: free(ip);
1284: free(host);
1.229 djm 1285: if (host_hostkeys != NULL)
1286: free_hostkeys(host_hostkeys);
1287: if (ip_hostkeys != NULL)
1288: free_hostkeys(ip_hostkeys);
1.108 markus 1289: return -1;
1290: }
1291:
1.337 djm 1292: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1293: int
1.337 djm 1294: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1295: {
1.267 djm 1296: u_int i;
1.337 djm 1297: int r = -1, flags = 0;
1.267 djm 1298: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1299: struct sshkey *plain = NULL;
1.229 djm 1300:
1.252 djm 1301: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1302: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.341 djm 1303: error_fr(r, "fingerprint host key");
1.252 djm 1304: r = -1;
1305: goto out;
1306: }
1307:
1.267 djm 1308: if (sshkey_is_cert(host_key)) {
1309: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1310: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.341 djm 1311: error_fr(r, "fingerprint CA key");
1.267 djm 1312: r = -1;
1313: goto out;
1314: }
1315: sshkey_format_cert_validity(host_key->cert,
1316: valid, sizeof(valid));
1317: debug("Server host certificate: %s %s, serial %llu "
1318: "ID \"%s\" CA %s %s valid %s",
1319: sshkey_ssh_name(host_key), fp,
1.269 djm 1320: (unsigned long long)host_key->cert->serial,
1321: host_key->cert->key_id,
1.267 djm 1322: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1323: valid);
1324: for (i = 0; i < host_key->cert->nprincipals; i++) {
1325: debug2("Server host certificate hostname: %s",
1326: host_key->cert->principals[i]);
1327: }
1328: } else {
1.276 djm 1329: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1330: }
1.252 djm 1331:
1332: if (sshkey_equal(previous_host_key, host_key)) {
1.341 djm 1333: debug2_f("server host key %s %s matches cached key",
1334: sshkey_type(host_key), fp);
1.252 djm 1335: r = 0;
1336: goto out;
1337: }
1338:
1339: /* Check in RevokedHostKeys file if specified */
1340: if (options.revoked_host_keys != NULL) {
1341: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1342: switch (r) {
1343: case 0:
1344: break; /* not revoked */
1345: case SSH_ERR_KEY_REVOKED:
1346: error("Host key %s %s revoked by file %s",
1347: sshkey_type(host_key), fp,
1348: options.revoked_host_keys);
1349: r = -1;
1350: goto out;
1351: default:
1.341 djm 1352: error_r(r, "Error checking host key %s %s in "
1353: "revoked keys file %s", sshkey_type(host_key),
1354: fp, options.revoked_host_keys);
1.252 djm 1355: r = -1;
1356: goto out;
1357: }
1.250 djm 1358: }
1359:
1.247 djm 1360: if (options.verify_host_key_dns) {
1361: /*
1362: * XXX certs are not yet supported for DNS, so downgrade
1363: * them and try the plain key.
1364: */
1.252 djm 1365: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1366: goto out;
1367: if (sshkey_is_cert(plain))
1368: sshkey_drop_cert(plain);
1.247 djm 1369: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1370: if (flags & DNS_VERIFY_FOUND) {
1371: if (options.verify_host_key_dns == 1 &&
1372: flags & DNS_VERIFY_MATCH &&
1373: flags & DNS_VERIFY_SECURE) {
1.250 djm 1374: r = 0;
1.252 djm 1375: goto out;
1.247 djm 1376: }
1377: if (flags & DNS_VERIFY_MATCH) {
1378: matching_host_key_dns = 1;
1379: } else {
1.287 djm 1380: warn_changed_key(plain);
1381: error("Update the SSHFP RR in DNS "
1382: "with the new host key to get rid "
1383: "of this message.");
1.247 djm 1384: }
1.153 jakob 1385: }
1.140 jakob 1386: }
1387: }
1.250 djm 1388: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1389: options.user_hostfiles, options.num_user_hostfiles,
1.337 djm 1390: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1391:
1.252 djm 1392: out:
1393: sshkey_free(plain);
1394: free(fp);
1.267 djm 1395: free(cafp);
1.337 djm 1396: if (r == 0 && host_key != NULL) {
1397: sshkey_free(previous_host_key);
1398: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1399: }
1400:
1401: return r;
1.51 markus 1402: }
1.70 markus 1403:
1.51 markus 1404: /*
1405: * Starts a dialog with the server, and authenticates the current user on the
1406: * server. This does not need any extra privileges. The basic connection
1407: * to the server must already have been established before this is called.
1408: * If login fails, this function prints an error and never returns.
1409: * This function does not require super-user privileges.
1410: */
1411: void
1.309 djm 1412: ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost,
1.229 djm 1413: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1414: {
1.241 djm 1415: char *host;
1.70 markus 1416: char *server_user, *local_user;
1.329 djm 1417: int r;
1.70 markus 1418:
1419: local_user = xstrdup(pw->pw_name);
1420: server_user = options.user ? options.user : local_user;
1.51 markus 1421:
1422: /* Convert the user-supplied hostname into all lowercase. */
1423: host = xstrdup(orighost);
1.241 djm 1424: lowercase(host);
1.51 markus 1425:
1426: /* Exchange protocol version identification strings with the server. */
1.329 djm 1427: if ((r = kex_exchange_identification(ssh, timeout_ms, NULL)) != 0)
1428: sshpkt_fatal(ssh, r, "banner exchange");
1.51 markus 1429:
1430: /* Put the connection into non-blocking mode. */
1.309 djm 1431: ssh_packet_set_nonblocking(ssh);
1.51 markus 1432:
1433: /* key exchange */
1434: /* authenticate user */
1.261 dtucker 1435: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.309 djm 1436: ssh_kex2(ssh, host, hostaddr, port);
1437: ssh_userauth2(ssh, local_user, server_user, host, sensitive);
1.238 djm 1438: free(local_user);
1.315 dtucker 1439: free(host);
1.132 markus 1440: }
1441:
1442: /* print all known host keys for a given host, but skip keys of given type */
1443: static int
1.279 markus 1444: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1445: {
1.242 djm 1446: int type[] = {
1447: KEY_RSA,
1448: KEY_DSA,
1449: KEY_ECDSA,
1450: KEY_ED25519,
1.297 markus 1451: KEY_XMSS,
1.242 djm 1452: -1
1453: };
1.229 djm 1454: int i, ret = 0;
1455: char *fp, *ra;
1456: const struct hostkey_entry *found;
1.132 markus 1457:
1458: for (i = 0; type[i] != -1; i++) {
1459: if (type[i] == key->type)
1460: continue;
1.335 djm 1461: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i],
1462: -1, &found))
1.132 markus 1463: continue;
1.259 djm 1464: fp = sshkey_fingerprint(found->key,
1.254 djm 1465: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1466: ra = sshkey_fingerprint(found->key,
1.254 djm 1467: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1468: if (fp == NULL || ra == NULL)
1.341 djm 1469: fatal_f("sshkey_fingerprint fail");
1.229 djm 1470: logit("WARNING: %s key found for host %s\n"
1471: "in %s:%lu\n"
1472: "%s key fingerprint %s.",
1.300 markus 1473: sshkey_type(found->key),
1.229 djm 1474: found->host, found->file, found->line,
1.300 markus 1475: sshkey_type(found->key), fp);
1.229 djm 1476: if (options.visual_host_key)
1477: logit("%s", ra);
1.238 djm 1478: free(ra);
1479: free(fp);
1.229 djm 1480: ret = 1;
1.132 markus 1481: }
1.229 djm 1482: return ret;
1.150 jakob 1483: }
1484:
1485: static void
1.279 markus 1486: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1487: {
1488: char *fp;
1489:
1.259 djm 1490: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1491: SSH_FP_DEFAULT);
1.259 djm 1492: if (fp == NULL)
1.341 djm 1493: fatal_f("sshkey_fingerprint fail");
1.150 jakob 1494:
1495: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1496: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1497: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1498: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1499: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1500: error("It is also possible that a host key has just been changed.");
1.150 jakob 1501: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.300 markus 1502: sshkey_type(host_key), fp);
1.150 jakob 1503: error("Please contact your system administrator.");
1504:
1.238 djm 1505: free(fp);
1.171 reyk 1506: }
1507:
1508: /*
1509: * Execute a local command
1510: */
1511: int
1512: ssh_local_cmd(const char *args)
1513: {
1514: char *shell;
1515: pid_t pid;
1516: int status;
1.231 djm 1517: void (*osighand)(int);
1.171 reyk 1518:
1519: if (!options.permit_local_command ||
1520: args == NULL || !*args)
1521: return (1);
1522:
1.226 djm 1523: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1524: shell = _PATH_BSHELL;
1525:
1.327 dtucker 1526: osighand = ssh_signal(SIGCHLD, SIG_DFL);
1.171 reyk 1527: pid = fork();
1528: if (pid == 0) {
1.327 dtucker 1529: ssh_signal(SIGPIPE, SIG_DFL);
1.171 reyk 1530: debug3("Executing %s -c \"%s\"", shell, args);
1531: execl(shell, shell, "-c", args, (char *)NULL);
1532: error("Couldn't execute %s -c \"%s\": %s",
1533: shell, args, strerror(errno));
1534: _exit(1);
1535: } else if (pid == -1)
1536: fatal("fork failed: %.100s", strerror(errno));
1537: while (waitpid(pid, &status, 0) == -1)
1538: if (errno != EINTR)
1539: fatal("Couldn't wait for child: %s", strerror(errno));
1.327 dtucker 1540: ssh_signal(SIGCHLD, osighand);
1.171 reyk 1541:
1542: if (!WIFEXITED(status))
1543: return (1);
1544:
1545: return (WEXITSTATUS(status));
1.266 jcs 1546: }
1547:
1548: void
1.328 djm 1549: maybe_add_key_to_agent(const char *authfile, struct sshkey *private,
1550: const char *comment, const char *passphrase)
1.266 jcs 1551: {
1552: int auth_sock = -1, r;
1.321 djm 1553: const char *skprovider = NULL;
1.266 jcs 1554:
1555: if (options.add_keys_to_agent == 0)
1556: return;
1557:
1558: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1559: debug3("no authentication agent, not adding key");
1560: return;
1561: }
1562:
1563: if (options.add_keys_to_agent == 2 &&
1564: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1565: debug3("user denied adding this key");
1.273 dtucker 1566: close(auth_sock);
1.266 jcs 1567: return;
1568: }
1.322 markus 1569: if (sshkey_is_sk(private))
1.321 djm 1570: skprovider = options.sk_provider;
1.328 djm 1571: if ((r = ssh_add_identity_constrained(auth_sock, private,
1.331 djm 1572: comment == NULL ? authfile : comment,
1573: options.add_keys_to_agent_lifespan,
1.321 djm 1574: (options.add_keys_to_agent == 3), 0, skprovider)) == 0)
1.266 jcs 1575: debug("identity added to agent: %s", authfile);
1576: else
1577: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1578: close(auth_sock);
1.1 deraadt 1579: }
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