Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.333
1.333 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.332 2020/09/09 21:57:27 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:
1.307 djm 96: static void
97: stderr_null(void)
98: {
99: int devnull;
100:
101: if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1) {
102: error("Can't open %s for stderr redirection: %s",
103: _PATH_DEVNULL, strerror(errno));
104: return;
105: }
106: if (devnull == STDERR_FILENO)
107: return;
108: if (dup2(devnull, STDERR_FILENO) == -1)
109: error("Cannot redirect stderr to %s", _PATH_DEVNULL);
110: if (devnull > STDERR_FILENO)
111: close(devnull);
112: }
113:
1.239 djm 114: /*
115: * Connect to the given ssh server using a proxy command that passes a
116: * a connected fd back to us.
117: */
118: static int
1.318 djm 119: ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host,
120: const char *host_arg, u_short port, const char *proxy_command)
1.239 djm 121: {
122: char *command_string;
123: int sp[2], sock;
124: pid_t pid;
125: char *shell;
126:
127: if ((shell = getenv("SHELL")) == NULL)
128: shell = _PATH_BSHELL;
129:
1.317 deraadt 130: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) == -1)
1.239 djm 131: fatal("Could not create socketpair to communicate with "
132: "proxy dialer: %.100s", strerror(errno));
133:
134: command_string = expand_proxy_command(proxy_command, options.user,
1.325 naddy 135: host, host_arg, port);
1.239 djm 136: debug("Executing proxy dialer command: %.500s", command_string);
137:
138: /* Fork and execute the proxy command. */
139: if ((pid = fork()) == 0) {
140: char *argv[10];
141:
142: close(sp[1]);
143: /* Redirect stdin and stdout. */
144: if (sp[0] != 0) {
1.317 deraadt 145: if (dup2(sp[0], 0) == -1)
1.239 djm 146: perror("dup2 stdin");
147: }
148: if (sp[0] != 1) {
1.317 deraadt 149: if (dup2(sp[0], 1) == -1)
1.239 djm 150: perror("dup2 stdout");
151: }
152: if (sp[0] >= 2)
153: close(sp[0]);
154:
155: /*
1.307 djm 156: * Stderr is left for non-ControlPersist connections is so
157: * error messages may be printed on the user's terminal.
1.239 djm 158: */
1.308 dtucker 159: if (!debug_flag && options.control_path != NULL &&
160: options.control_persist)
1.307 djm 161: stderr_null();
162:
1.239 djm 163: argv[0] = shell;
164: argv[1] = "-c";
165: argv[2] = command_string;
166: argv[3] = NULL;
167:
168: /*
169: * Execute the proxy command.
170: * Note that we gave up any extra privileges above.
171: */
172: execv(argv[0], argv);
173: perror(argv[0]);
174: exit(1);
175: }
176: /* Parent. */
1.317 deraadt 177: if (pid == -1)
1.239 djm 178: fatal("fork failed: %.100s", strerror(errno));
179: close(sp[0]);
180: free(command_string);
181:
182: if ((sock = mm_receive_fd(sp[1])) == -1)
183: fatal("proxy dialer did not pass back a connection");
1.271 markus 184: close(sp[1]);
1.239 djm 185:
186: while (waitpid(pid, NULL, 0) == -1)
187: if (errno != EINTR)
188: fatal("Couldn't wait for child: %s", strerror(errno));
189:
190: /* Set the connection file descriptors. */
1.286 djm 191: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
192: return -1; /* ssh_packet_set_connection logs error */
1.239 djm 193:
194: return 0;
195: }
196:
1.39 deraadt 197: /*
198: * Connect to the given ssh server using a proxy command.
199: */
1.109 itojun 200: static int
1.318 djm 201: ssh_proxy_connect(struct ssh *ssh, const char *host, const char *host_arg,
202: u_short port, const char *proxy_command)
1.1 deraadt 203: {
1.239 djm 204: char *command_string;
1.38 markus 205: int pin[2], pout[2];
1.69 deraadt 206: pid_t pid;
1.239 djm 207: char *shell;
1.237 markus 208:
1.226 djm 209: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 210: shell = _PATH_BSHELL;
1.38 markus 211:
212: /* Create pipes for communicating with the proxy. */
1.317 deraadt 213: if (pipe(pin) == -1 || pipe(pout) == -1)
1.38 markus 214: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 215: strerror(errno));
1.38 markus 216:
1.239 djm 217: command_string = expand_proxy_command(proxy_command, options.user,
1.325 naddy 218: host, host_arg, port);
1.38 markus 219: debug("Executing proxy command: %.500s", command_string);
220:
221: /* Fork and execute the proxy command. */
222: if ((pid = fork()) == 0) {
223: char *argv[10];
224:
225: /* Redirect stdin and stdout. */
226: close(pin[1]);
227: if (pin[0] != 0) {
1.317 deraadt 228: if (dup2(pin[0], 0) == -1)
1.38 markus 229: perror("dup2 stdin");
230: close(pin[0]);
231: }
232: close(pout[0]);
1.317 deraadt 233: if (dup2(pout[1], 1) == -1)
1.38 markus 234: perror("dup2 stdout");
235: /* Cannot be 1 because pin allocated two descriptors. */
236: close(pout[1]);
237:
1.307 djm 238: /*
239: * Stderr is left for non-ControlPersist connections is so
240: * error messages may be printed on the user's terminal.
241: */
1.308 dtucker 242: if (!debug_flag && options.control_path != NULL &&
243: options.control_persist)
1.307 djm 244: stderr_null();
245:
1.201 djm 246: argv[0] = shell;
1.38 markus 247: argv[1] = "-c";
248: argv[2] = command_string;
249: argv[3] = NULL;
250:
251: /* Execute the proxy command. Note that we gave up any
252: extra privileges above. */
1.327 dtucker 253: ssh_signal(SIGPIPE, SIG_DFL);
1.89 markus 254: execv(argv[0], argv);
255: perror(argv[0]);
1.38 markus 256: exit(1);
257: }
258: /* Parent. */
1.317 deraadt 259: if (pid == -1)
1.38 markus 260: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 261: else
262: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 263:
264: /* Close child side of the descriptors. */
265: close(pin[0]);
266: close(pout[1]);
267:
268: /* Free the command name. */
1.238 djm 269: free(command_string);
1.38 markus 270:
271: /* Set the connection file descriptors. */
1.286 djm 272: if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
273: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 274:
1.110 markus 275: return 0;
1.227 djm 276: }
277:
278: void
279: ssh_kill_proxy_command(void)
280: {
281: /*
282: * Send SIGHUP to proxy command if used. We don't wait() in
283: * case it hangs and instead rely on init to reap the child
284: */
285: if (proxy_command_pid > 1)
1.228 djm 286: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 287: }
288:
1.39 deraadt 289: /*
1.295 djm 290: * Search a interface address list (returned from getifaddrs(3)) for an
1.298 djm 291: * address that matches the desired address family on the specified interface.
1.295 djm 292: * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure.
293: */
294: static int
295: check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs,
296: struct sockaddr_storage *resultp, socklen_t *rlenp)
297: {
298: struct sockaddr_in6 *sa6;
299: struct sockaddr_in *sa;
300: struct in6_addr *v6addr;
301: const struct ifaddrs *ifa;
302: int allow_local;
303:
304: /*
305: * Prefer addresses that are not loopback or linklocal, but use them
306: * if nothing else matches.
307: */
308: for (allow_local = 0; allow_local < 2; allow_local++) {
309: for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
310: if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL ||
311: (ifa->ifa_flags & IFF_UP) == 0 ||
312: ifa->ifa_addr->sa_family != af ||
313: strcmp(ifa->ifa_name, options.bind_interface) != 0)
314: continue;
315: switch (ifa->ifa_addr->sa_family) {
316: case AF_INET:
317: sa = (struct sockaddr_in *)ifa->ifa_addr;
318: if (!allow_local && sa->sin_addr.s_addr ==
319: htonl(INADDR_LOOPBACK))
320: continue;
321: if (*rlenp < sizeof(struct sockaddr_in)) {
322: error("%s: v4 addr doesn't fit",
323: __func__);
324: return -1;
325: }
326: *rlenp = sizeof(struct sockaddr_in);
327: memcpy(resultp, sa, *rlenp);
328: return 0;
329: case AF_INET6:
330: sa6 = (struct sockaddr_in6 *)ifa->ifa_addr;
331: v6addr = &sa6->sin6_addr;
332: if (!allow_local &&
333: (IN6_IS_ADDR_LINKLOCAL(v6addr) ||
334: IN6_IS_ADDR_LOOPBACK(v6addr)))
335: continue;
336: if (*rlenp < sizeof(struct sockaddr_in6)) {
337: error("%s: v6 addr doesn't fit",
338: __func__);
339: return -1;
340: }
341: *rlenp = sizeof(struct sockaddr_in6);
342: memcpy(resultp, sa6, *rlenp);
343: return 0;
344: }
345: }
346: }
347: return -1;
348: }
349:
350: /*
1.303 dtucker 351: * Creates a socket for use as the ssh connection.
1.39 deraadt 352: */
1.109 itojun 353: static int
1.302 dtucker 354: ssh_create_socket(struct addrinfo *ai)
1.1 deraadt 355: {
1.301 dtucker 356: int sock, r;
1.295 djm 357: struct sockaddr_storage bindaddr;
358: socklen_t bindaddrlen = 0;
1.246 djm 359: struct addrinfo hints, *res = NULL;
1.295 djm 360: struct ifaddrs *ifaddrs = NULL;
361: char ntop[NI_MAXHOST];
1.1 deraadt 362:
1.217 dtucker 363: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.317 deraadt 364: if (sock == -1) {
1.240 djm 365: error("socket: %s", strerror(errno));
1.216 dtucker 366: return -1;
367: }
368: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 369:
370: /* Bind the socket to an alternative local IP address */
1.302 dtucker 371: if (options.bind_address == NULL && options.bind_interface == NULL)
1.105 markus 372: return sock;
373:
1.295 djm 374: if (options.bind_address != NULL) {
1.246 djm 375: memset(&hints, 0, sizeof(hints));
376: hints.ai_family = ai->ai_family;
377: hints.ai_socktype = ai->ai_socktype;
378: hints.ai_protocol = ai->ai_protocol;
379: hints.ai_flags = AI_PASSIVE;
1.295 djm 380: if ((r = getaddrinfo(options.bind_address, NULL,
381: &hints, &res)) != 0) {
1.246 djm 382: error("getaddrinfo: %s: %s", options.bind_address,
1.295 djm 383: ssh_gai_strerror(r));
384: goto fail;
385: }
1.296 dtucker 386: if (res == NULL) {
1.295 djm 387: error("getaddrinfo: no addrs");
388: goto fail;
389: }
390: memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
391: bindaddrlen = res->ai_addrlen;
392: } else if (options.bind_interface != NULL) {
393: if ((r = getifaddrs(&ifaddrs)) != 0) {
394: error("getifaddrs: %s: %s", options.bind_interface,
395: strerror(errno));
396: goto fail;
397: }
398: bindaddrlen = sizeof(bindaddr);
399: if (check_ifaddrs(options.bind_interface, ai->ai_family,
400: ifaddrs, &bindaddr, &bindaddrlen) != 0) {
401: logit("getifaddrs: %s: no suitable addresses",
402: options.bind_interface);
403: goto fail;
1.246 djm 404: }
1.105 markus 405: }
1.295 djm 406: if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
407: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
408: error("%s: getnameinfo failed: %s", __func__,
409: ssh_gai_strerror(r));
410: goto fail;
411: }
1.301 dtucker 412: if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
1.295 djm 413: error("bind %s: %s", ntop, strerror(errno));
414: goto fail;
1.38 markus 415: }
1.295 djm 416: debug("%s: bound to %s", __func__, ntop);
417: /* success */
418: goto out;
419: fail:
420: close(sock);
421: sock = -1;
422: out:
1.246 djm 423: if (res != NULL)
424: freeaddrinfo(res);
1.295 djm 425: if (ifaddrs != NULL)
426: freeifaddrs(ifaddrs);
1.38 markus 427: return sock;
1.1 deraadt 428: }
429:
1.282 djm 430: /*
1.49 markus 431: * Opens a TCP/IP connection to the remote server on the given host.
432: * The address of the remote host will be returned in hostaddr.
1.302 dtucker 433: * If port is 0, the default port will be used.
1.39 deraadt 434: * Connection_attempts specifies the maximum number of tries (one per
435: * second). If proxy_command is non-NULL, it specifies the command (with %h
436: * and %p substituted for host and port, respectively) to use to contact
437: * the daemon.
438: */
1.241 djm 439: static int
1.286 djm 440: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.241 djm 441: struct sockaddr_storage *hostaddr, u_short port, int family,
1.302 dtucker 442: int connection_attempts, int *timeout_ms, int want_keepalive)
1.1 deraadt 443: {
1.313 dtucker 444: int on = 1, saved_timeout_ms = *timeout_ms;
1.290 djm 445: int oerrno, sock = -1, attempt;
1.90 markus 446: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 447: struct addrinfo *ai;
1.38 markus 448:
1.302 dtucker 449: debug2("%s", __func__);
1.268 djm 450: memset(ntop, 0, sizeof(ntop));
451: memset(strport, 0, sizeof(strport));
1.38 markus 452:
1.181 markus 453: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 454: if (attempt > 0) {
455: /* Sleep a moment before retrying. */
456: sleep(1);
1.38 markus 457: debug("Trying again...");
1.200 markus 458: }
1.181 markus 459: /*
460: * Loop through addresses for this host, and try each one in
461: * sequence until the connection succeeds.
462: */
1.49 markus 463: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 464: if (ai->ai_family != AF_INET &&
1.290 djm 465: ai->ai_family != AF_INET6) {
466: errno = EAFNOSUPPORT;
1.49 markus 467: continue;
1.290 djm 468: }
1.49 markus 469: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
470: ntop, sizeof(ntop), strport, sizeof(strport),
471: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.290 djm 472: oerrno = errno;
1.265 djm 473: error("%s: getnameinfo failed", __func__);
1.290 djm 474: errno = oerrno;
1.49 markus 475: continue;
476: }
477: debug("Connecting to %.200s [%.100s] port %s.",
478: host, ntop, strport);
479:
480: /* Create a socket for connecting. */
1.302 dtucker 481: sock = ssh_create_socket(ai);
1.292 stsp 482: if (sock < 0) {
1.110 markus 483: /* Any error is already output */
1.290 djm 484: errno = 0;
1.49 markus 485: continue;
1.292 stsp 486: }
1.49 markus 487:
1.313 dtucker 488: *timeout_ms = saved_timeout_ms;
1.141 djm 489: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 490: timeout_ms) >= 0) {
1.49 markus 491: /* Successful connection. */
1.102 markus 492: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 493: break;
1.49 markus 494: } else {
1.290 djm 495: oerrno = errno;
1.131 itojun 496: debug("connect to address %s port %s: %s",
497: ntop, strport, strerror(errno));
1.38 markus 498: close(sock);
1.181 markus 499: sock = -1;
1.290 djm 500: errno = oerrno;
1.38 markus 501: }
502: }
1.181 markus 503: if (sock != -1)
1.49 markus 504: break; /* Successful connection. */
1.38 markus 505: }
1.49 markus 506:
1.38 markus 507: /* Return failure if we didn't get a successful connection. */
1.181 markus 508: if (sock == -1) {
1.159 markus 509: error("ssh: connect to host %s port %s: %s",
1.290 djm 510: host, strport, errno == 0 ? "failure" : strerror(errno));
511: return -1;
1.130 itojun 512: }
1.38 markus 513:
514: debug("Connection established.");
1.90 markus 515:
1.155 markus 516: /* Set SO_KEEPALIVE if requested. */
1.202 djm 517: if (want_keepalive &&
1.90 markus 518: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1.317 deraadt 519: sizeof(on)) == -1)
1.90 markus 520: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 521:
522: /* Set the connection. */
1.286 djm 523: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
524: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 525:
1.319 djm 526: return 0;
1.59 markus 527: }
528:
1.241 djm 529: int
1.318 djm 530: ssh_connect(struct ssh *ssh, const char *host, const char *host_arg,
531: struct addrinfo *addrs, struct sockaddr_storage *hostaddr, u_short port,
532: int family, int connection_attempts, int *timeout_ms, int want_keepalive)
1.241 djm 533: {
1.314 markus 534: int in, out;
535:
1.241 djm 536: if (options.proxy_command == NULL) {
1.286 djm 537: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
1.302 dtucker 538: family, connection_attempts, timeout_ms, want_keepalive);
1.241 djm 539: } else if (strcmp(options.proxy_command, "-") == 0) {
1.317 deraadt 540: if ((in = dup(STDIN_FILENO)) == -1 ||
541: (out = dup(STDOUT_FILENO)) == -1) {
1.314 markus 542: if (in >= 0)
543: close(in);
544: error("%s: dup() in/out failed", __func__);
545: return -1; /* ssh_packet_set_connection logs error */
546: }
547: if ((ssh_packet_set_connection(ssh, in, out)) == NULL)
1.286 djm 548: return -1; /* ssh_packet_set_connection logs error */
549: return 0;
1.241 djm 550: } else if (options.proxy_use_fdpass) {
1.318 djm 551: return ssh_proxy_fdpass_connect(ssh, host, host_arg, port,
1.241 djm 552: options.proxy_command);
553: }
1.318 djm 554: return ssh_proxy_connect(ssh, host, host_arg, port,
555: options.proxy_command);
1.241 djm 556: }
557:
1.96 markus 558: /* defaults to 'no' */
1.109 itojun 559: static int
1.312 dtucker 560: confirm(const char *prompt, const char *fingerprint)
1.1 deraadt 561: {
1.119 markus 562: const char *msg, *again = "Please type 'yes' or 'no': ";
1.312 dtucker 563: const char *again_fp = "Please type 'yes', 'no' or the fingerprint: ";
1.326 dtucker 564: char *p, *cp;
1.119 markus 565: int ret = -1;
1.96 markus 566:
567: if (options.batch_mode)
568: return 0;
1.312 dtucker 569: for (msg = prompt;;msg = fingerprint ? again_fp : again) {
1.326 dtucker 570: cp = p = read_passphrase(msg, RP_ECHO);
1.289 djm 571: if (p == NULL)
572: return 0;
1.326 dtucker 573: p += strspn(p, " \t"); /* skip leading whitespace */
574: p[strcspn(p, " \t\n")] = '\0'; /* remove trailing whitespace */
1.289 djm 575: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 576: ret = 0;
1.312 dtucker 577: else if (strcasecmp(p, "yes") == 0 || (fingerprint != NULL &&
1.332 djm 578: strcmp(p, fingerprint) == 0))
1.119 markus 579: ret = 1;
1.326 dtucker 580: free(cp);
1.119 markus 581: if (ret != -1)
582: return ret;
1.1 deraadt 583: }
584: }
585:
1.219 djm 586: static int
1.305 djm 587: check_host_cert(const char *host, const struct sshkey *key)
1.219 djm 588: {
589: const char *reason;
1.305 djm 590: int r;
1.219 djm 591:
1.305 djm 592: if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) {
1.219 djm 593: error("%s", reason);
594: return 0;
595: }
1.305 djm 596: if (sshbuf_len(key->cert->critical) != 0) {
1.223 djm 597: error("Certificate for %s contains unsupported "
598: "critical options(s)", host);
1.219 djm 599: return 0;
600: }
1.305 djm 601: if ((r = sshkey_check_cert_sigtype(key,
602: options.ca_sign_algorithms)) != 0) {
603: logit("%s: certificate signature algorithm %s: %s", __func__,
604: (key->cert == NULL || key->cert->signature_type == NULL) ?
605: "(null)" : key->cert->signature_type, ssh_err(r));
606: return 0;
607: }
608:
1.219 djm 609: return 1;
610: }
611:
1.229 djm 612: static int
613: sockaddr_is_local(struct sockaddr *hostaddr)
614: {
615: switch (hostaddr->sa_family) {
616: case AF_INET:
617: return (ntohl(((struct sockaddr_in *)hostaddr)->
618: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
619: case AF_INET6:
620: return IN6_IS_ADDR_LOOPBACK(
621: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
622: default:
623: return 0;
624: }
625: }
626:
627: /*
628: * Prepare the hostname and ip address strings that are used to lookup
629: * host keys in known_hosts files. These may have a port number appended.
630: */
631: void
632: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
633: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
634: {
635: char ntop[NI_MAXHOST];
636:
637: /*
638: * We don't have the remote ip-address for connections
639: * using a proxy command
640: */
641: if (hostfile_ipaddr != NULL) {
642: if (options.proxy_command == NULL) {
643: if (getnameinfo(hostaddr, hostaddr->sa_len,
644: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 645: fatal("%s: getnameinfo failed", __func__);
1.229 djm 646: *hostfile_ipaddr = put_host_port(ntop, port);
647: } else {
648: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
649: "command>");
650: }
651: }
652:
653: /*
654: * Allow the user to record the key under a different name or
655: * differentiate a non-standard port. This is useful for ssh
656: * tunneling over forwarded connections or if you run multiple
657: * sshd's on different ports on the same machine.
658: */
659: if (hostfile_hostname != NULL) {
660: if (options.host_key_alias != NULL) {
661: *hostfile_hostname = xstrdup(options.host_key_alias);
662: debug("using hostkeyalias: %s", *hostfile_hostname);
663: } else {
664: *hostfile_hostname = put_host_port(hostname, port);
665: }
666: }
667: }
668:
1.39 deraadt 669: /*
1.108 markus 670: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 671: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.333 ! djm 672: *
! 673: * If cert_fallbackp is not NULL then will attempt to convert certificate host
! 674: * keys to plain keys if no certificate match was found and will return
! 675: * non-zero via *cert_fallbackp if this fall-back was used.
1.39 deraadt 676: */
1.197 dtucker 677: #define RDRW 0
678: #define RDONLY 1
679: #define ROQUIET 2
1.109 itojun 680: static int
1.197 dtucker 681: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 682: struct sshkey *host_key, int readonly,
1.234 djm 683: char **user_hostfiles, u_int num_user_hostfiles,
1.333 ! djm 684: char **system_hostfiles, u_int num_system_hostfiles, int *cert_fallbackp)
1.1 deraadt 685: {
1.234 djm 686: HostStatus host_status;
687: HostStatus ip_status;
1.279 markus 688: struct sshkey *raw_key = NULL;
1.189 dtucker 689: char *ip = NULL, *host = NULL;
1.204 grunk 690: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 691: char msg[1024];
1.234 djm 692: const char *type;
693: const struct hostkey_entry *host_found, *ip_found;
1.312 dtucker 694: int len, cancelled_forwarding = 0, confirmed;
1.333 ! djm 695: int local = sockaddr_is_local(hostaddr), cert_fallback = 0;
1.280 markus 696: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 697: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 698: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 699: u_int i;
1.49 markus 700:
1.333 ! djm 701: if (cert_fallbackp != NULL)
! 702: *cert_fallbackp = 0;
! 703:
1.49 markus 704: /*
705: * Force accepting of the host key for loopback/localhost. The
706: * problem is that if the home directory is NFS-mounted to multiple
707: * machines, localhost will refer to a different machine in each of
708: * them, and the user will get bogus HOST_CHANGED warnings. This
709: * essentially disables host authentication for localhost; however,
710: * this is probably not a real problem.
711: */
1.111 markus 712: if (options.no_host_authentication_for_localhost == 1 && local &&
713: options.host_key_alias == NULL) {
1.88 markus 714: debug("Forcing accepting of host key for "
715: "loopback/localhost.");
1.108 markus 716: return 0;
1.49 markus 717: }
1.42 markus 718:
719: /*
1.229 djm 720: * Prepare the hostname and address strings used for hostkey lookup.
721: * In some cases, these will have a port number appended.
1.42 markus 722: */
1.229 djm 723: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 724:
725: /*
1.88 markus 726: * Turn off check_host_ip if the connection is to localhost, via proxy
727: * command or if we don't have a hostname to compare with
728: */
1.189 dtucker 729: if (options.check_host_ip && (local ||
730: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 731: options.check_host_ip = 0;
1.86 markus 732:
1.229 djm 733: host_hostkeys = init_hostkeys();
1.234 djm 734: for (i = 0; i < num_user_hostfiles; i++)
735: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
736: for (i = 0; i < num_system_hostfiles; i++)
737: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 738:
739: ip_hostkeys = NULL;
740: if (!want_cert && options.check_host_ip) {
741: ip_hostkeys = init_hostkeys();
1.234 djm 742: for (i = 0; i < num_user_hostfiles; i++)
743: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
744: for (i = 0; i < num_system_hostfiles; i++)
745: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 746: }
1.38 markus 747:
1.219 djm 748: retry:
1.229 djm 749: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 750: want_cert = sshkey_is_cert(host_key);
751: type = sshkey_type(host_key);
1.219 djm 752:
1.46 markus 753: /*
1.170 djm 754: * Check if the host key is present in the user's list of known
1.40 markus 755: * hosts or in the systemwide list.
756: */
1.229 djm 757: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
758: &host_found);
759:
1.40 markus 760: /*
761: * Also perform check for the ip address, skip the check if we are
1.219 djm 762: * localhost, looking for a certificate, or the hostname was an ip
763: * address to begin with.
1.40 markus 764: */
1.229 djm 765: if (!want_cert && ip_hostkeys != NULL) {
766: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
767: &ip_found);
1.38 markus 768: if (host_status == HOST_CHANGED &&
1.319 djm 769: (ip_status != HOST_CHANGED ||
1.229 djm 770: (ip_found != NULL &&
1.280 markus 771: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 772: host_ip_differ = 1;
773: } else
774: ip_status = host_status;
775:
776: switch (host_status) {
777: case HOST_OK:
778: /* The host is known and the key matches. */
1.219 djm 779: debug("Host '%.200s' is known and matches the %s host %s.",
780: host, type, want_cert ? "certificate" : "key");
1.229 djm 781: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
782: host_found->file, host_found->line);
1.281 djm 783: if (want_cert &&
784: !check_host_cert(options.host_key_alias == NULL ?
785: hostname : options.host_key_alias, host_key))
1.219 djm 786: goto fail;
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)
808: fatal("%s: sshkey_fingerprint fail", __func__);
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");
1.333 ! djm 819: /*
! 820: * NB. do not perform cert->key fallback in this
! 821: * recursive call. Fallback will only be performed in
! 822: * the top-level call.
! 823: */
1.212 stevesk 824: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 825: ROQUIET, user_hostfiles, num_user_hostfiles,
1.333 ! djm 826: system_hostfiles, num_system_hostfiles,
! 827: NULL) == 0) {
1.197 dtucker 828: debug("found matching key w/out port");
829: break;
830: }
831: }
1.219 djm 832: if (readonly || want_cert)
1.108 markus 833: goto fail;
1.38 markus 834: /* The host is new. */
1.285 djm 835: if (options.strict_host_key_checking ==
836: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 837: /*
838: * User has requested strict host key checking. We
839: * will not add the host key automatically. The only
840: * alternative left is to abort.
841: */
842: error("No %s host key is known for %.200s and you "
843: "have requested strict checking.", type, host);
844: goto fail;
1.285 djm 845: } else if (options.strict_host_key_checking ==
846: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 847: char msg1[1024], msg2[1024];
848:
1.229 djm 849: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 850: snprintf(msg1, sizeof(msg1),
1.168 djm 851: "\nbut keys of different type are already"
852: " known for this host.");
1.145 jakob 853: else
854: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 855: /* The default */
1.259 djm 856: fp = sshkey_fingerprint(host_key,
1.254 djm 857: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 858: ra = sshkey_fingerprint(host_key,
1.254 djm 859: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 860: if (fp == NULL || ra == NULL)
861: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 862: msg2[0] = '\0';
863: if (options.verify_host_key_dns) {
1.153 jakob 864: if (matching_host_key_dns)
1.145 jakob 865: snprintf(msg2, sizeof(msg2),
866: "Matching host key fingerprint"
867: " found in DNS.\n");
868: else
869: snprintf(msg2, sizeof(msg2),
870: "No matching host key fingerprint"
871: " found in DNS.\n");
872: }
1.119 markus 873: snprintf(msg, sizeof(msg),
1.108 markus 874: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 875: "established%s\n"
1.209 grunk 876: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 877: "Are you sure you want to continue connecting "
1.312 dtucker 878: "(yes/no/[fingerprint])? ",
1.209 grunk 879: host, ip, msg1, type, fp,
880: options.visual_host_key ? "\n" : "",
881: options.visual_host_key ? ra : "",
882: msg2);
1.238 djm 883: free(ra);
1.312 dtucker 884: confirmed = confirm(msg, fp);
1.238 djm 885: free(fp);
1.312 dtucker 886: if (!confirmed)
1.108 markus 887: goto fail;
1.257 djm 888: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 889: }
1.161 djm 890: /*
1.285 djm 891: * If in "new" or "off" strict mode, add the key automatically
892: * to the local known_hosts file.
1.161 djm 893: */
1.88 markus 894: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 895: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 896: hostp = hostline;
1.161 djm 897: if (options.hash_known_hosts) {
898: /* Add hash of host and IP separately */
1.234 djm 899: r = add_host_to_hostfile(user_hostfiles[0],
900: host, host_key, options.hash_known_hosts) &&
901: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 902: host_key, options.hash_known_hosts);
903: } else {
904: /* Add unhashed "host,ip" */
1.234 djm 905: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 906: hostline, host_key,
907: options.hash_known_hosts);
908: }
909: } else {
1.234 djm 910: r = add_host_to_hostfile(user_hostfiles[0], host,
911: host_key, options.hash_known_hosts);
1.38 markus 912: hostp = host;
1.161 djm 913: }
1.38 markus 914:
1.161 djm 915: if (!r)
1.138 itojun 916: logit("Failed to add the host to the list of known "
1.234 djm 917: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 918: else
1.138 itojun 919: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 920: "list of known hosts.", hostp, type);
1.38 markus 921: break;
1.220 djm 922: case HOST_REVOKED:
923: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
924: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
925: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
926: error("The %s host key for %s is marked as revoked.", type, host);
927: error("This could mean that a stolen key is being used to");
928: error("impersonate this host.");
929:
930: /*
931: * If strict host key checking is in use, the user will have
932: * to edit the key manually and we can only abort.
933: */
1.285 djm 934: if (options.strict_host_key_checking !=
935: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 936: error("%s host key for %.200s was revoked and you have "
937: "requested strict checking.", type, host);
938: goto fail;
939: }
940: goto continue_unsafe;
941:
1.38 markus 942: case HOST_CHANGED:
1.219 djm 943: if (want_cert) {
944: /*
945: * This is only a debug() since it is valid to have
946: * CAs with wildcard DNS matches that don't match
947: * all hosts that one might visit.
948: */
949: debug("Host certificate authority does not "
1.229 djm 950: "match %s in %s:%lu", CA_MARKER,
951: host_found->file, host_found->line);
1.219 djm 952: goto fail;
953: }
1.197 dtucker 954: if (readonly == ROQUIET)
955: goto fail;
1.38 markus 956: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 957: char *key_msg;
1.38 markus 958: if (ip_status == HOST_NEW)
1.158 avsm 959: key_msg = "is unknown";
1.38 markus 960: else if (ip_status == HOST_OK)
1.158 avsm 961: key_msg = "is unchanged";
1.38 markus 962: else
1.158 avsm 963: key_msg = "has a different value";
1.38 markus 964: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
965: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
966: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 967: error("The %s host key for %s has changed,", type, host);
1.208 ian 968: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 969: error("%s. This could either mean that", key_msg);
1.38 markus 970: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 971: error("and its host key have changed at the same time.");
1.88 markus 972: if (ip_status != HOST_NEW)
1.229 djm 973: error("Offending key for IP in %s:%lu",
974: ip_found->file, ip_found->line);
1.38 markus 975: }
976: /* The host key has changed. */
1.150 jakob 977: warn_changed_key(host_key);
1.38 markus 978: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 979: user_hostfiles[0]);
1.280 markus 980: error("Offending %s key in %s:%lu",
981: sshkey_type(host_found->key),
1.229 djm 982: host_found->file, host_found->line);
1.38 markus 983:
1.40 markus 984: /*
985: * If strict host key checking is in use, the user will have
986: * to edit the key manually and we can only abort.
987: */
1.285 djm 988: if (options.strict_host_key_checking !=
989: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 990: error("%s host key for %.200s has changed and you have "
991: "requested strict checking.", type, host);
992: goto fail;
993: }
1.38 markus 994:
1.220 djm 995: continue_unsafe:
1.40 markus 996: /*
997: * If strict host key checking has not been requested, allow
1.144 djm 998: * the connection but without MITM-able authentication or
1.194 stevesk 999: * forwarding.
1.40 markus 1000: */
1.38 markus 1001: if (options.password_authentication) {
1.108 markus 1002: error("Password authentication is disabled to avoid "
1003: "man-in-the-middle attacks.");
1.38 markus 1004: options.password_authentication = 0;
1.210 dtucker 1005: cancelled_forwarding = 1;
1.144 djm 1006: }
1007: if (options.kbd_interactive_authentication) {
1008: error("Keyboard-interactive authentication is disabled"
1009: " to avoid man-in-the-middle attacks.");
1010: options.kbd_interactive_authentication = 0;
1011: options.challenge_response_authentication = 0;
1.210 dtucker 1012: cancelled_forwarding = 1;
1.144 djm 1013: }
1014: if (options.challenge_response_authentication) {
1015: error("Challenge/response authentication is disabled"
1016: " to avoid man-in-the-middle attacks.");
1017: options.challenge_response_authentication = 0;
1.210 dtucker 1018: cancelled_forwarding = 1;
1.38 markus 1019: }
1020: if (options.forward_agent) {
1.108 markus 1021: error("Agent forwarding is disabled to avoid "
1022: "man-in-the-middle attacks.");
1.38 markus 1023: options.forward_agent = 0;
1.210 dtucker 1024: cancelled_forwarding = 1;
1.83 markus 1025: }
1026: if (options.forward_x11) {
1.108 markus 1027: error("X11 forwarding is disabled to avoid "
1028: "man-in-the-middle attacks.");
1.83 markus 1029: options.forward_x11 = 0;
1.210 dtucker 1030: cancelled_forwarding = 1;
1.83 markus 1031: }
1.108 markus 1032: if (options.num_local_forwards > 0 ||
1033: options.num_remote_forwards > 0) {
1034: error("Port forwarding is disabled to avoid "
1035: "man-in-the-middle attacks.");
1036: options.num_local_forwards =
1.118 deraadt 1037: options.num_remote_forwards = 0;
1.210 dtucker 1038: cancelled_forwarding = 1;
1.194 stevesk 1039: }
1040: if (options.tun_open != SSH_TUNMODE_NO) {
1041: error("Tunnel forwarding is disabled to avoid "
1042: "man-in-the-middle attacks.");
1043: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1044: cancelled_forwarding = 1;
1.38 markus 1045: }
1.210 dtucker 1046: if (options.exit_on_forward_failure && cancelled_forwarding)
1047: fatal("Error: forwarding disabled due to host key "
1048: "check failure");
1049:
1.40 markus 1050: /*
1051: * XXX Should permit the user to change to use the new id.
1052: * This could be done by converting the host key to an
1053: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1054: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1055: * accept the authentication.
1056: */
1.38 markus 1057: break;
1.132 markus 1058: case HOST_FOUND:
1059: fatal("internal error");
1060: break;
1.88 markus 1061: }
1062:
1063: if (options.check_host_ip && host_status != HOST_CHANGED &&
1064: ip_status == HOST_CHANGED) {
1.119 markus 1065: snprintf(msg, sizeof(msg),
1066: "Warning: the %s host key for '%.200s' "
1067: "differs from the key for the IP address '%.128s'"
1.229 djm 1068: "\nOffending key for IP in %s:%lu",
1069: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1070: if (host_status == HOST_OK) {
1071: len = strlen(msg);
1072: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1073: "\nMatching host key in %s:%lu",
1074: host_found->file, host_found->line);
1.119 markus 1075: }
1.285 djm 1076: if (options.strict_host_key_checking ==
1077: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1078: strlcat(msg, "\nAre you sure you want "
1079: "to continue connecting (yes/no)? ", sizeof(msg));
1.312 dtucker 1080: if (!confirm(msg, NULL))
1.108 markus 1081: goto fail;
1.285 djm 1082: } else if (options.strict_host_key_checking !=
1083: SSH_STRICT_HOSTKEY_OFF) {
1084: logit("%s", msg);
1085: error("Exiting, you have requested strict checking.");
1086: goto fail;
1.119 markus 1087: } else {
1.143 djm 1088: logit("%s", msg);
1.88 markus 1089: }
1.257 djm 1090: }
1091:
1092: if (!hostkey_trusted && options.update_hostkeys) {
1093: debug("%s: hostkey not known or explicitly trusted: "
1094: "disabling UpdateHostkeys", __func__);
1095: options.update_hostkeys = 0;
1.38 markus 1096: }
1.82 provos 1097:
1.238 djm 1098: free(ip);
1099: free(host);
1.229 djm 1100: if (host_hostkeys != NULL)
1101: free_hostkeys(host_hostkeys);
1102: if (ip_hostkeys != NULL)
1103: free_hostkeys(ip_hostkeys);
1.333 ! djm 1104: if (cert_fallbackp != NULL)
! 1105: *cert_fallbackp = cert_fallback;
1.108 markus 1106: return 0;
1107:
1108: fail:
1.333 ! djm 1109: if (cert_fallbackp != NULL && want_cert &&
! 1110: host_status != HOST_REVOKED) {
1.219 djm 1111: /*
1112: * No matching certificate. Downgrade cert to raw key and
1113: * search normally.
1114: */
1115: debug("No matching CA found. Retry with plain key");
1.280 markus 1116: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1117: fatal("%s: sshkey_from_private: %s",
1118: __func__, ssh_err(r));
1119: if ((r = sshkey_drop_cert(raw_key)) != 0)
1120: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1121: host_key = raw_key;
1.333 ! djm 1122: cert_fallback = 1;
1.219 djm 1123: goto retry;
1124: }
1.293 dtucker 1125: sshkey_free(raw_key);
1.238 djm 1126: free(ip);
1127: free(host);
1.229 djm 1128: if (host_hostkeys != NULL)
1129: free_hostkeys(host_hostkeys);
1130: if (ip_hostkeys != NULL)
1131: free_hostkeys(ip_hostkeys);
1.108 markus 1132: return -1;
1133: }
1134:
1.333 ! djm 1135: /*
! 1136: * returns 0 if key verifies or -1 if key does NOT verify.
! 1137: *
! 1138: * If the host key was a certificate that was downgraded to a plain key in
! 1139: * the process of matching, then cert_fallbackp will be non-zero.
! 1140: */
1.108 markus 1141: int
1.333 ! djm 1142: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key,
! 1143: int *cert_fallbackp)
1.108 markus 1144: {
1.267 djm 1145: u_int i;
1.333 ! djm 1146: int r = -1, flags = 0, cert_fallback = 0;
1.267 djm 1147: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1148: struct sshkey *plain = NULL;
1.229 djm 1149:
1.333 ! djm 1150: if (cert_fallbackp != NULL)
! 1151: *cert_fallbackp = 0;
! 1152:
1.252 djm 1153: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1154: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1155: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1156: r = -1;
1157: goto out;
1158: }
1159:
1.267 djm 1160: if (sshkey_is_cert(host_key)) {
1161: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1162: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1163: error("%s: fingerprint CA key: %s",
1164: __func__, ssh_err(r));
1165: r = -1;
1166: goto out;
1167: }
1168: sshkey_format_cert_validity(host_key->cert,
1169: valid, sizeof(valid));
1170: debug("Server host certificate: %s %s, serial %llu "
1171: "ID \"%s\" CA %s %s valid %s",
1172: sshkey_ssh_name(host_key), fp,
1.269 djm 1173: (unsigned long long)host_key->cert->serial,
1174: host_key->cert->key_id,
1.267 djm 1175: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1176: valid);
1177: for (i = 0; i < host_key->cert->nprincipals; i++) {
1178: debug2("Server host certificate hostname: %s",
1179: host_key->cert->principals[i]);
1180: }
1181: } else {
1.276 djm 1182: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1183: }
1.252 djm 1184:
1185: if (sshkey_equal(previous_host_key, host_key)) {
1186: debug2("%s: server host key %s %s matches cached key",
1187: __func__, sshkey_type(host_key), fp);
1188: r = 0;
1189: goto out;
1190: }
1191:
1192: /* Check in RevokedHostKeys file if specified */
1193: if (options.revoked_host_keys != NULL) {
1194: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1195: switch (r) {
1196: case 0:
1197: break; /* not revoked */
1198: case SSH_ERR_KEY_REVOKED:
1199: error("Host key %s %s revoked by file %s",
1200: sshkey_type(host_key), fp,
1201: options.revoked_host_keys);
1202: r = -1;
1203: goto out;
1204: default:
1205: error("Error checking host key %s %s in "
1206: "revoked keys file %s: %s", sshkey_type(host_key),
1207: fp, options.revoked_host_keys, ssh_err(r));
1208: r = -1;
1209: goto out;
1210: }
1.250 djm 1211: }
1212:
1.247 djm 1213: if (options.verify_host_key_dns) {
1214: /*
1215: * XXX certs are not yet supported for DNS, so downgrade
1216: * them and try the plain key.
1217: */
1.252 djm 1218: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1219: goto out;
1220: if (sshkey_is_cert(plain))
1221: sshkey_drop_cert(plain);
1.247 djm 1222: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1223: if (flags & DNS_VERIFY_FOUND) {
1224: if (options.verify_host_key_dns == 1 &&
1225: flags & DNS_VERIFY_MATCH &&
1226: flags & DNS_VERIFY_SECURE) {
1.250 djm 1227: r = 0;
1.252 djm 1228: goto out;
1.247 djm 1229: }
1230: if (flags & DNS_VERIFY_MATCH) {
1231: matching_host_key_dns = 1;
1232: } else {
1.287 djm 1233: warn_changed_key(plain);
1234: error("Update the SSHFP RR in DNS "
1235: "with the new host key to get rid "
1236: "of this message.");
1.247 djm 1237: }
1.153 jakob 1238: }
1.140 jakob 1239: }
1240: }
1.250 djm 1241: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1242: options.user_hostfiles, options.num_user_hostfiles,
1.333 ! djm 1243: options.system_hostfiles, options.num_system_hostfiles,
! 1244: &cert_fallback);
1.250 djm 1245:
1.252 djm 1246: out:
1247: sshkey_free(plain);
1248: free(fp);
1.267 djm 1249: free(cafp);
1.333 ! djm 1250: if (r == 0) {
! 1251: if (host_key != NULL) {
! 1252: sshkey_free(previous_host_key);
! 1253: r = sshkey_from_private(host_key, &previous_host_key);
! 1254: }
! 1255: if (r == 0 && cert_fallbackp != NULL)
! 1256: *cert_fallbackp = cert_fallback;
1.250 djm 1257: }
1258:
1259: return r;
1.51 markus 1260: }
1.70 markus 1261:
1.51 markus 1262: /*
1263: * Starts a dialog with the server, and authenticates the current user on the
1264: * server. This does not need any extra privileges. The basic connection
1265: * to the server must already have been established before this is called.
1266: * If login fails, this function prints an error and never returns.
1267: * This function does not require super-user privileges.
1268: */
1269: void
1.309 djm 1270: ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost,
1.229 djm 1271: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1272: {
1.241 djm 1273: char *host;
1.70 markus 1274: char *server_user, *local_user;
1.329 djm 1275: int r;
1.70 markus 1276:
1277: local_user = xstrdup(pw->pw_name);
1278: server_user = options.user ? options.user : local_user;
1.51 markus 1279:
1280: /* Convert the user-supplied hostname into all lowercase. */
1281: host = xstrdup(orighost);
1.241 djm 1282: lowercase(host);
1.51 markus 1283:
1284: /* Exchange protocol version identification strings with the server. */
1.329 djm 1285: if ((r = kex_exchange_identification(ssh, timeout_ms, NULL)) != 0)
1286: sshpkt_fatal(ssh, r, "banner exchange");
1.51 markus 1287:
1288: /* Put the connection into non-blocking mode. */
1.309 djm 1289: ssh_packet_set_nonblocking(ssh);
1.51 markus 1290:
1291: /* key exchange */
1292: /* authenticate user */
1.261 dtucker 1293: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.309 djm 1294: ssh_kex2(ssh, host, hostaddr, port);
1295: ssh_userauth2(ssh, local_user, server_user, host, sensitive);
1.238 djm 1296: free(local_user);
1.315 dtucker 1297: free(host);
1.132 markus 1298: }
1299:
1300: /* print all known host keys for a given host, but skip keys of given type */
1301: static int
1.279 markus 1302: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1303: {
1.242 djm 1304: int type[] = {
1305: KEY_RSA,
1306: KEY_DSA,
1307: KEY_ECDSA,
1308: KEY_ED25519,
1.297 markus 1309: KEY_XMSS,
1.242 djm 1310: -1
1311: };
1.229 djm 1312: int i, ret = 0;
1313: char *fp, *ra;
1314: const struct hostkey_entry *found;
1.132 markus 1315:
1316: for (i = 0; type[i] != -1; i++) {
1317: if (type[i] == key->type)
1318: continue;
1.229 djm 1319: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1320: continue;
1.259 djm 1321: fp = sshkey_fingerprint(found->key,
1.254 djm 1322: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1323: ra = sshkey_fingerprint(found->key,
1.254 djm 1324: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1325: if (fp == NULL || ra == NULL)
1326: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1327: logit("WARNING: %s key found for host %s\n"
1328: "in %s:%lu\n"
1329: "%s key fingerprint %s.",
1.300 markus 1330: sshkey_type(found->key),
1.229 djm 1331: found->host, found->file, found->line,
1.300 markus 1332: sshkey_type(found->key), fp);
1.229 djm 1333: if (options.visual_host_key)
1334: logit("%s", ra);
1.238 djm 1335: free(ra);
1336: free(fp);
1.229 djm 1337: ret = 1;
1.132 markus 1338: }
1.229 djm 1339: return ret;
1.150 jakob 1340: }
1341:
1342: static void
1.279 markus 1343: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1344: {
1345: char *fp;
1346:
1.259 djm 1347: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1348: SSH_FP_DEFAULT);
1.259 djm 1349: if (fp == NULL)
1350: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1351:
1352: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1353: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1354: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1355: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1356: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1357: error("It is also possible that a host key has just been changed.");
1.150 jakob 1358: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.300 markus 1359: sshkey_type(host_key), fp);
1.150 jakob 1360: error("Please contact your system administrator.");
1361:
1.238 djm 1362: free(fp);
1.171 reyk 1363: }
1364:
1365: /*
1366: * Execute a local command
1367: */
1368: int
1369: ssh_local_cmd(const char *args)
1370: {
1371: char *shell;
1372: pid_t pid;
1373: int status;
1.231 djm 1374: void (*osighand)(int);
1.171 reyk 1375:
1376: if (!options.permit_local_command ||
1377: args == NULL || !*args)
1378: return (1);
1379:
1.226 djm 1380: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1381: shell = _PATH_BSHELL;
1382:
1.327 dtucker 1383: osighand = ssh_signal(SIGCHLD, SIG_DFL);
1.171 reyk 1384: pid = fork();
1385: if (pid == 0) {
1.327 dtucker 1386: ssh_signal(SIGPIPE, SIG_DFL);
1.171 reyk 1387: debug3("Executing %s -c \"%s\"", shell, args);
1388: execl(shell, shell, "-c", args, (char *)NULL);
1389: error("Couldn't execute %s -c \"%s\": %s",
1390: shell, args, strerror(errno));
1391: _exit(1);
1392: } else if (pid == -1)
1393: fatal("fork failed: %.100s", strerror(errno));
1394: while (waitpid(pid, &status, 0) == -1)
1395: if (errno != EINTR)
1396: fatal("Couldn't wait for child: %s", strerror(errno));
1.327 dtucker 1397: ssh_signal(SIGCHLD, osighand);
1.171 reyk 1398:
1399: if (!WIFEXITED(status))
1400: return (1);
1401:
1402: return (WEXITSTATUS(status));
1.266 jcs 1403: }
1404:
1405: void
1.328 djm 1406: maybe_add_key_to_agent(const char *authfile, struct sshkey *private,
1407: const char *comment, const char *passphrase)
1.266 jcs 1408: {
1409: int auth_sock = -1, r;
1.321 djm 1410: const char *skprovider = NULL;
1.266 jcs 1411:
1412: if (options.add_keys_to_agent == 0)
1413: return;
1414:
1415: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1416: debug3("no authentication agent, not adding key");
1417: return;
1418: }
1419:
1420: if (options.add_keys_to_agent == 2 &&
1421: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1422: debug3("user denied adding this key");
1.273 dtucker 1423: close(auth_sock);
1.266 jcs 1424: return;
1425: }
1.322 markus 1426: if (sshkey_is_sk(private))
1.321 djm 1427: skprovider = options.sk_provider;
1.328 djm 1428: if ((r = ssh_add_identity_constrained(auth_sock, private,
1.331 djm 1429: comment == NULL ? authfile : comment,
1430: options.add_keys_to_agent_lifespan,
1.321 djm 1431: (options.add_keys_to_agent == 3), 0, skprovider)) == 0)
1.266 jcs 1432: debug("identity added to agent: %s", authfile);
1433: else
1434: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1435: close(auth_sock);
1.1 deraadt 1436: }
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