Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.319
1.319 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.318 2019/09/13 04:27:35 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>
1.193 stevesk 34: #include <string.h>
1.192 stevesk 35: #include <unistd.h>
1.295 djm 36: #include <ifaddrs.h>
1.71 markus 37:
1.199 deraadt 38: #include "xmalloc.h"
1.91 markus 39: #include "ssh.h"
1.299 markus 40: #include "sshbuf.h"
1.1 deraadt 41: #include "packet.h"
1.21 markus 42: #include "compat.h"
1.300 markus 43: #include "sshkey.h"
1.71 markus 44: #include "sshconnect.h"
1.58 markus 45: #include "hostfile.h"
1.91 markus 46: #include "log.h"
1.251 millert 47: #include "misc.h"
1.91 markus 48: #include "readconf.h"
49: #include "atomicio.h"
1.140 jakob 50: #include "dns.h"
1.239 djm 51: #include "monitor_fdpass.h"
1.219 djm 52: #include "ssh2.h"
1.186 stevesk 53: #include "version.h"
1.252 djm 54: #include "authfile.h"
55: #include "ssherr.h"
1.266 jcs 56: #include "authfd.h"
1.309 djm 57: #include "kex.h"
1.310 djm 58:
1.279 markus 59: struct sshkey *previous_host_key = NULL;
1.59 markus 60:
1.169 stevesk 61: static int matching_host_key_dns = 0;
1.145 jakob 62:
1.227 djm 63: static pid_t proxy_command_pid = 0;
64:
1.124 markus 65: /* import */
1.307 djm 66: extern int debug_flag;
1.43 markus 67: extern Options options;
1.50 markus 68: extern char *__progname;
1.91 markus 69:
1.279 markus 70: static int show_other_keys(struct hostkeys *, struct sshkey *);
71: static void warn_changed_key(struct sshkey *);
1.132 markus 72:
1.239 djm 73: /* Expand a proxy command */
74: static char *
75: expand_proxy_command(const char *proxy_command, const char *user,
1.318 djm 76: const char *host, const char *host_arg, int port)
1.239 djm 77: {
78: char *tmp, *ret, strport[NI_MAXSERV];
79:
1.241 djm 80: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 81: xasprintf(&tmp, "exec %s", proxy_command);
1.318 djm 82: ret = percent_expand(tmp,
83: "h", host,
84: "n", host_arg,
85: "p", strport,
86: "r", options.user,
87: (char *)NULL);
1.239 djm 88: free(tmp);
89: return ret;
90: }
91:
1.307 djm 92: static void
93: stderr_null(void)
94: {
95: int devnull;
96:
97: if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1) {
98: error("Can't open %s for stderr redirection: %s",
99: _PATH_DEVNULL, strerror(errno));
100: return;
101: }
102: if (devnull == STDERR_FILENO)
103: return;
104: if (dup2(devnull, STDERR_FILENO) == -1)
105: error("Cannot redirect stderr to %s", _PATH_DEVNULL);
106: if (devnull > STDERR_FILENO)
107: close(devnull);
108: }
109:
1.239 djm 110: /*
111: * Connect to the given ssh server using a proxy command that passes a
112: * a connected fd back to us.
113: */
114: static int
1.318 djm 115: ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host,
116: const char *host_arg, u_short port, const char *proxy_command)
1.239 djm 117: {
118: char *command_string;
119: int sp[2], sock;
120: pid_t pid;
121: char *shell;
122:
123: if ((shell = getenv("SHELL")) == NULL)
124: shell = _PATH_BSHELL;
125:
1.317 deraadt 126: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) == -1)
1.239 djm 127: fatal("Could not create socketpair to communicate with "
128: "proxy dialer: %.100s", strerror(errno));
129:
130: command_string = expand_proxy_command(proxy_command, options.user,
1.318 djm 131: host_arg, host, port);
1.239 djm 132: debug("Executing proxy dialer command: %.500s", command_string);
133:
134: /* Fork and execute the proxy command. */
135: if ((pid = fork()) == 0) {
136: char *argv[10];
137:
138: close(sp[1]);
139: /* Redirect stdin and stdout. */
140: if (sp[0] != 0) {
1.317 deraadt 141: if (dup2(sp[0], 0) == -1)
1.239 djm 142: perror("dup2 stdin");
143: }
144: if (sp[0] != 1) {
1.317 deraadt 145: if (dup2(sp[0], 1) == -1)
1.239 djm 146: perror("dup2 stdout");
147: }
148: if (sp[0] >= 2)
149: close(sp[0]);
150:
151: /*
1.307 djm 152: * Stderr is left for non-ControlPersist connections is so
153: * error messages may be printed on the user's terminal.
1.239 djm 154: */
1.308 dtucker 155: if (!debug_flag && options.control_path != NULL &&
156: options.control_persist)
1.307 djm 157: stderr_null();
158:
1.239 djm 159: argv[0] = shell;
160: argv[1] = "-c";
161: argv[2] = command_string;
162: argv[3] = NULL;
163:
164: /*
165: * Execute the proxy command.
166: * Note that we gave up any extra privileges above.
167: */
168: execv(argv[0], argv);
169: perror(argv[0]);
170: exit(1);
171: }
172: /* Parent. */
1.317 deraadt 173: if (pid == -1)
1.239 djm 174: fatal("fork failed: %.100s", strerror(errno));
175: close(sp[0]);
176: free(command_string);
177:
178: if ((sock = mm_receive_fd(sp[1])) == -1)
179: fatal("proxy dialer did not pass back a connection");
1.271 markus 180: close(sp[1]);
1.239 djm 181:
182: while (waitpid(pid, NULL, 0) == -1)
183: if (errno != EINTR)
184: fatal("Couldn't wait for child: %s", strerror(errno));
185:
186: /* Set the connection file descriptors. */
1.286 djm 187: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
188: return -1; /* ssh_packet_set_connection logs error */
1.239 djm 189:
190: return 0;
191: }
192:
1.39 deraadt 193: /*
194: * Connect to the given ssh server using a proxy command.
195: */
1.109 itojun 196: static int
1.318 djm 197: ssh_proxy_connect(struct ssh *ssh, const char *host, const char *host_arg,
198: u_short port, const char *proxy_command)
1.1 deraadt 199: {
1.239 djm 200: char *command_string;
1.38 markus 201: int pin[2], pout[2];
1.69 deraadt 202: pid_t pid;
1.239 djm 203: char *shell;
1.237 markus 204:
1.226 djm 205: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 206: shell = _PATH_BSHELL;
1.38 markus 207:
208: /* Create pipes for communicating with the proxy. */
1.317 deraadt 209: if (pipe(pin) == -1 || pipe(pout) == -1)
1.38 markus 210: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 211: strerror(errno));
1.38 markus 212:
1.239 djm 213: command_string = expand_proxy_command(proxy_command, options.user,
1.318 djm 214: host_arg, host, port);
1.38 markus 215: debug("Executing proxy command: %.500s", command_string);
216:
217: /* Fork and execute the proxy command. */
218: if ((pid = fork()) == 0) {
219: char *argv[10];
220:
221: /* Redirect stdin and stdout. */
222: close(pin[1]);
223: if (pin[0] != 0) {
1.317 deraadt 224: if (dup2(pin[0], 0) == -1)
1.38 markus 225: perror("dup2 stdin");
226: close(pin[0]);
227: }
228: close(pout[0]);
1.317 deraadt 229: if (dup2(pout[1], 1) == -1)
1.38 markus 230: perror("dup2 stdout");
231: /* Cannot be 1 because pin allocated two descriptors. */
232: close(pout[1]);
233:
1.307 djm 234: /*
235: * Stderr is left for non-ControlPersist connections is so
236: * error messages may be printed on the user's terminal.
237: */
1.308 dtucker 238: if (!debug_flag && options.control_path != NULL &&
239: options.control_persist)
1.307 djm 240: stderr_null();
241:
1.201 djm 242: argv[0] = shell;
1.38 markus 243: argv[1] = "-c";
244: argv[2] = command_string;
245: argv[3] = NULL;
246:
247: /* Execute the proxy command. Note that we gave up any
248: extra privileges above. */
1.232 djm 249: signal(SIGPIPE, SIG_DFL);
1.89 markus 250: execv(argv[0], argv);
251: perror(argv[0]);
1.38 markus 252: exit(1);
253: }
254: /* Parent. */
1.317 deraadt 255: if (pid == -1)
1.38 markus 256: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 257: else
258: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 259:
260: /* Close child side of the descriptors. */
261: close(pin[0]);
262: close(pout[1]);
263:
264: /* Free the command name. */
1.238 djm 265: free(command_string);
1.38 markus 266:
267: /* Set the connection file descriptors. */
1.286 djm 268: if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
269: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 270:
1.110 markus 271: return 0;
1.227 djm 272: }
273:
274: void
275: ssh_kill_proxy_command(void)
276: {
277: /*
278: * Send SIGHUP to proxy command if used. We don't wait() in
279: * case it hangs and instead rely on init to reap the child
280: */
281: if (proxy_command_pid > 1)
1.228 djm 282: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 283: }
284:
1.39 deraadt 285: /*
1.295 djm 286: * Search a interface address list (returned from getifaddrs(3)) for an
1.298 djm 287: * address that matches the desired address family on the specified interface.
1.295 djm 288: * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure.
289: */
290: static int
291: check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs,
292: struct sockaddr_storage *resultp, socklen_t *rlenp)
293: {
294: struct sockaddr_in6 *sa6;
295: struct sockaddr_in *sa;
296: struct in6_addr *v6addr;
297: const struct ifaddrs *ifa;
298: int allow_local;
299:
300: /*
301: * Prefer addresses that are not loopback or linklocal, but use them
302: * if nothing else matches.
303: */
304: for (allow_local = 0; allow_local < 2; allow_local++) {
305: for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
306: if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL ||
307: (ifa->ifa_flags & IFF_UP) == 0 ||
308: ifa->ifa_addr->sa_family != af ||
309: strcmp(ifa->ifa_name, options.bind_interface) != 0)
310: continue;
311: switch (ifa->ifa_addr->sa_family) {
312: case AF_INET:
313: sa = (struct sockaddr_in *)ifa->ifa_addr;
314: if (!allow_local && sa->sin_addr.s_addr ==
315: htonl(INADDR_LOOPBACK))
316: continue;
317: if (*rlenp < sizeof(struct sockaddr_in)) {
318: error("%s: v4 addr doesn't fit",
319: __func__);
320: return -1;
321: }
322: *rlenp = sizeof(struct sockaddr_in);
323: memcpy(resultp, sa, *rlenp);
324: return 0;
325: case AF_INET6:
326: sa6 = (struct sockaddr_in6 *)ifa->ifa_addr;
327: v6addr = &sa6->sin6_addr;
328: if (!allow_local &&
329: (IN6_IS_ADDR_LINKLOCAL(v6addr) ||
330: IN6_IS_ADDR_LOOPBACK(v6addr)))
331: continue;
332: if (*rlenp < sizeof(struct sockaddr_in6)) {
333: error("%s: v6 addr doesn't fit",
334: __func__);
335: return -1;
336: }
337: *rlenp = sizeof(struct sockaddr_in6);
338: memcpy(resultp, sa6, *rlenp);
339: return 0;
340: }
341: }
342: }
343: return -1;
344: }
345:
346: /*
1.303 dtucker 347: * Creates a socket for use as the ssh connection.
1.39 deraadt 348: */
1.109 itojun 349: static int
1.302 dtucker 350: ssh_create_socket(struct addrinfo *ai)
1.1 deraadt 351: {
1.301 dtucker 352: int sock, r;
1.295 djm 353: struct sockaddr_storage bindaddr;
354: socklen_t bindaddrlen = 0;
1.246 djm 355: struct addrinfo hints, *res = NULL;
1.295 djm 356: struct ifaddrs *ifaddrs = NULL;
357: char ntop[NI_MAXHOST];
1.1 deraadt 358:
1.217 dtucker 359: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.317 deraadt 360: if (sock == -1) {
1.240 djm 361: error("socket: %s", strerror(errno));
1.216 dtucker 362: return -1;
363: }
364: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 365:
366: /* Bind the socket to an alternative local IP address */
1.302 dtucker 367: if (options.bind_address == NULL && options.bind_interface == NULL)
1.105 markus 368: return sock;
369:
1.295 djm 370: if (options.bind_address != NULL) {
1.246 djm 371: memset(&hints, 0, sizeof(hints));
372: hints.ai_family = ai->ai_family;
373: hints.ai_socktype = ai->ai_socktype;
374: hints.ai_protocol = ai->ai_protocol;
375: hints.ai_flags = AI_PASSIVE;
1.295 djm 376: if ((r = getaddrinfo(options.bind_address, NULL,
377: &hints, &res)) != 0) {
1.246 djm 378: error("getaddrinfo: %s: %s", options.bind_address,
1.295 djm 379: ssh_gai_strerror(r));
380: goto fail;
381: }
1.296 dtucker 382: if (res == NULL) {
1.295 djm 383: error("getaddrinfo: no addrs");
384: goto fail;
385: }
386: memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
387: bindaddrlen = res->ai_addrlen;
388: } else if (options.bind_interface != NULL) {
389: if ((r = getifaddrs(&ifaddrs)) != 0) {
390: error("getifaddrs: %s: %s", options.bind_interface,
391: strerror(errno));
392: goto fail;
393: }
394: bindaddrlen = sizeof(bindaddr);
395: if (check_ifaddrs(options.bind_interface, ai->ai_family,
396: ifaddrs, &bindaddr, &bindaddrlen) != 0) {
397: logit("getifaddrs: %s: no suitable addresses",
398: options.bind_interface);
399: goto fail;
1.246 djm 400: }
1.105 markus 401: }
1.295 djm 402: if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
403: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
404: error("%s: getnameinfo failed: %s", __func__,
405: ssh_gai_strerror(r));
406: goto fail;
407: }
1.301 dtucker 408: if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
1.295 djm 409: error("bind %s: %s", ntop, strerror(errno));
410: goto fail;
1.38 markus 411: }
1.295 djm 412: debug("%s: bound to %s", __func__, ntop);
413: /* success */
414: goto out;
415: fail:
416: close(sock);
417: sock = -1;
418: out:
1.246 djm 419: if (res != NULL)
420: freeaddrinfo(res);
1.295 djm 421: if (ifaddrs != NULL)
422: freeifaddrs(ifaddrs);
1.38 markus 423: return sock;
1.1 deraadt 424: }
425:
1.282 djm 426: /*
1.49 markus 427: * Opens a TCP/IP connection to the remote server on the given host.
428: * The address of the remote host will be returned in hostaddr.
1.302 dtucker 429: * If port is 0, the default port will be used.
1.39 deraadt 430: * Connection_attempts specifies the maximum number of tries (one per
431: * second). If proxy_command is non-NULL, it specifies the command (with %h
432: * and %p substituted for host and port, respectively) to use to contact
433: * the daemon.
434: */
1.241 djm 435: static int
1.286 djm 436: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.241 djm 437: struct sockaddr_storage *hostaddr, u_short port, int family,
1.302 dtucker 438: int connection_attempts, int *timeout_ms, int want_keepalive)
1.1 deraadt 439: {
1.313 dtucker 440: int on = 1, saved_timeout_ms = *timeout_ms;
1.290 djm 441: int oerrno, sock = -1, attempt;
1.90 markus 442: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 443: struct addrinfo *ai;
1.38 markus 444:
1.302 dtucker 445: debug2("%s", __func__);
1.268 djm 446: memset(ntop, 0, sizeof(ntop));
447: memset(strport, 0, sizeof(strport));
1.38 markus 448:
1.181 markus 449: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 450: if (attempt > 0) {
451: /* Sleep a moment before retrying. */
452: sleep(1);
1.38 markus 453: debug("Trying again...");
1.200 markus 454: }
1.181 markus 455: /*
456: * Loop through addresses for this host, and try each one in
457: * sequence until the connection succeeds.
458: */
1.49 markus 459: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 460: if (ai->ai_family != AF_INET &&
1.290 djm 461: ai->ai_family != AF_INET6) {
462: errno = EAFNOSUPPORT;
1.49 markus 463: continue;
1.290 djm 464: }
1.49 markus 465: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
466: ntop, sizeof(ntop), strport, sizeof(strport),
467: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.290 djm 468: oerrno = errno;
1.265 djm 469: error("%s: getnameinfo failed", __func__);
1.290 djm 470: errno = oerrno;
1.49 markus 471: continue;
472: }
473: debug("Connecting to %.200s [%.100s] port %s.",
474: host, ntop, strport);
475:
476: /* Create a socket for connecting. */
1.302 dtucker 477: sock = ssh_create_socket(ai);
1.292 stsp 478: if (sock < 0) {
1.110 markus 479: /* Any error is already output */
1.290 djm 480: errno = 0;
1.49 markus 481: continue;
1.292 stsp 482: }
1.49 markus 483:
1.313 dtucker 484: *timeout_ms = saved_timeout_ms;
1.141 djm 485: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 486: timeout_ms) >= 0) {
1.49 markus 487: /* Successful connection. */
1.102 markus 488: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 489: break;
1.49 markus 490: } else {
1.290 djm 491: oerrno = errno;
1.131 itojun 492: debug("connect to address %s port %s: %s",
493: ntop, strport, strerror(errno));
1.38 markus 494: close(sock);
1.181 markus 495: sock = -1;
1.290 djm 496: errno = oerrno;
1.38 markus 497: }
498: }
1.181 markus 499: if (sock != -1)
1.49 markus 500: break; /* Successful connection. */
1.38 markus 501: }
1.49 markus 502:
1.38 markus 503: /* Return failure if we didn't get a successful connection. */
1.181 markus 504: if (sock == -1) {
1.159 markus 505: error("ssh: connect to host %s port %s: %s",
1.290 djm 506: host, strport, errno == 0 ? "failure" : strerror(errno));
507: return -1;
1.130 itojun 508: }
1.38 markus 509:
510: debug("Connection established.");
1.90 markus 511:
1.155 markus 512: /* Set SO_KEEPALIVE if requested. */
1.202 djm 513: if (want_keepalive &&
1.90 markus 514: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1.317 deraadt 515: sizeof(on)) == -1)
1.90 markus 516: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 517:
518: /* Set the connection. */
1.286 djm 519: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
520: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 521:
1.319 ! djm 522: return 0;
1.59 markus 523: }
524:
1.241 djm 525: int
1.318 djm 526: ssh_connect(struct ssh *ssh, const char *host, const char *host_arg,
527: struct addrinfo *addrs, struct sockaddr_storage *hostaddr, u_short port,
528: int family, int connection_attempts, int *timeout_ms, int want_keepalive)
1.241 djm 529: {
1.314 markus 530: int in, out;
531:
1.241 djm 532: if (options.proxy_command == NULL) {
1.286 djm 533: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
1.302 dtucker 534: family, connection_attempts, timeout_ms, want_keepalive);
1.241 djm 535: } else if (strcmp(options.proxy_command, "-") == 0) {
1.317 deraadt 536: if ((in = dup(STDIN_FILENO)) == -1 ||
537: (out = dup(STDOUT_FILENO)) == -1) {
1.314 markus 538: if (in >= 0)
539: close(in);
540: error("%s: dup() in/out failed", __func__);
541: return -1; /* ssh_packet_set_connection logs error */
542: }
543: if ((ssh_packet_set_connection(ssh, in, out)) == NULL)
1.286 djm 544: return -1; /* ssh_packet_set_connection logs error */
545: return 0;
1.241 djm 546: } else if (options.proxy_use_fdpass) {
1.318 djm 547: return ssh_proxy_fdpass_connect(ssh, host, host_arg, port,
1.241 djm 548: options.proxy_command);
549: }
1.318 djm 550: return ssh_proxy_connect(ssh, host, host_arg, port,
551: options.proxy_command);
1.241 djm 552: }
553:
1.96 markus 554: /* defaults to 'no' */
1.109 itojun 555: static int
1.312 dtucker 556: confirm(const char *prompt, const char *fingerprint)
1.1 deraadt 557: {
1.119 markus 558: const char *msg, *again = "Please type 'yes' or 'no': ";
1.312 dtucker 559: const char *again_fp = "Please type 'yes', 'no' or the fingerprint: ";
1.119 markus 560: char *p;
561: int ret = -1;
1.96 markus 562:
563: if (options.batch_mode)
564: return 0;
1.312 dtucker 565: for (msg = prompt;;msg = fingerprint ? again_fp : again) {
1.119 markus 566: p = read_passphrase(msg, RP_ECHO);
1.289 djm 567: if (p == NULL)
568: return 0;
569: p[strcspn(p, "\n")] = '\0';
570: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 571: ret = 0;
1.312 dtucker 572: else if (strcasecmp(p, "yes") == 0 || (fingerprint != NULL &&
573: strcasecmp(p, fingerprint) == 0))
1.119 markus 574: ret = 1;
1.238 djm 575: free(p);
1.119 markus 576: if (ret != -1)
577: return ret;
1.1 deraadt 578: }
579: }
580:
1.219 djm 581: static int
1.305 djm 582: check_host_cert(const char *host, const struct sshkey *key)
1.219 djm 583: {
584: const char *reason;
1.305 djm 585: int r;
1.219 djm 586:
1.305 djm 587: if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) {
1.219 djm 588: error("%s", reason);
589: return 0;
590: }
1.305 djm 591: if (sshbuf_len(key->cert->critical) != 0) {
1.223 djm 592: error("Certificate for %s contains unsupported "
593: "critical options(s)", host);
1.219 djm 594: return 0;
595: }
1.305 djm 596: if ((r = sshkey_check_cert_sigtype(key,
597: options.ca_sign_algorithms)) != 0) {
598: logit("%s: certificate signature algorithm %s: %s", __func__,
599: (key->cert == NULL || key->cert->signature_type == NULL) ?
600: "(null)" : key->cert->signature_type, ssh_err(r));
601: return 0;
602: }
603:
1.219 djm 604: return 1;
605: }
606:
1.229 djm 607: static int
608: sockaddr_is_local(struct sockaddr *hostaddr)
609: {
610: switch (hostaddr->sa_family) {
611: case AF_INET:
612: return (ntohl(((struct sockaddr_in *)hostaddr)->
613: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
614: case AF_INET6:
615: return IN6_IS_ADDR_LOOPBACK(
616: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
617: default:
618: return 0;
619: }
620: }
621:
622: /*
623: * Prepare the hostname and ip address strings that are used to lookup
624: * host keys in known_hosts files. These may have a port number appended.
625: */
626: void
627: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
628: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
629: {
630: char ntop[NI_MAXHOST];
631:
632: /*
633: * We don't have the remote ip-address for connections
634: * using a proxy command
635: */
636: if (hostfile_ipaddr != NULL) {
637: if (options.proxy_command == NULL) {
638: if (getnameinfo(hostaddr, hostaddr->sa_len,
639: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 640: fatal("%s: getnameinfo failed", __func__);
1.229 djm 641: *hostfile_ipaddr = put_host_port(ntop, port);
642: } else {
643: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
644: "command>");
645: }
646: }
647:
648: /*
649: * Allow the user to record the key under a different name or
650: * differentiate a non-standard port. This is useful for ssh
651: * tunneling over forwarded connections or if you run multiple
652: * sshd's on different ports on the same machine.
653: */
654: if (hostfile_hostname != NULL) {
655: if (options.host_key_alias != NULL) {
656: *hostfile_hostname = xstrdup(options.host_key_alias);
657: debug("using hostkeyalias: %s", *hostfile_hostname);
658: } else {
659: *hostfile_hostname = put_host_port(hostname, port);
660: }
661: }
662: }
663:
1.39 deraadt 664: /*
1.108 markus 665: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 666: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 667: */
1.197 dtucker 668: #define RDRW 0
669: #define RDONLY 1
670: #define ROQUIET 2
1.109 itojun 671: static int
1.197 dtucker 672: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 673: struct sshkey *host_key, int readonly,
1.234 djm 674: char **user_hostfiles, u_int num_user_hostfiles,
675: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 676: {
1.234 djm 677: HostStatus host_status;
678: HostStatus ip_status;
1.279 markus 679: struct sshkey *raw_key = NULL;
1.189 dtucker 680: char *ip = NULL, *host = NULL;
1.204 grunk 681: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 682: char msg[1024];
1.234 djm 683: const char *type;
684: const struct hostkey_entry *host_found, *ip_found;
1.312 dtucker 685: int len, cancelled_forwarding = 0, confirmed;
1.234 djm 686: int local = sockaddr_is_local(hostaddr);
1.280 markus 687: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 688: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 689: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 690: u_int i;
1.49 markus 691:
692: /*
693: * Force accepting of the host key for loopback/localhost. The
694: * problem is that if the home directory is NFS-mounted to multiple
695: * machines, localhost will refer to a different machine in each of
696: * them, and the user will get bogus HOST_CHANGED warnings. This
697: * essentially disables host authentication for localhost; however,
698: * this is probably not a real problem.
699: */
1.111 markus 700: if (options.no_host_authentication_for_localhost == 1 && local &&
701: options.host_key_alias == NULL) {
1.88 markus 702: debug("Forcing accepting of host key for "
703: "loopback/localhost.");
1.108 markus 704: return 0;
1.49 markus 705: }
1.42 markus 706:
707: /*
1.229 djm 708: * Prepare the hostname and address strings used for hostkey lookup.
709: * In some cases, these will have a port number appended.
1.42 markus 710: */
1.229 djm 711: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 712:
713: /*
1.88 markus 714: * Turn off check_host_ip if the connection is to localhost, via proxy
715: * command or if we don't have a hostname to compare with
716: */
1.189 dtucker 717: if (options.check_host_ip && (local ||
718: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 719: options.check_host_ip = 0;
1.86 markus 720:
1.229 djm 721: host_hostkeys = init_hostkeys();
1.234 djm 722: for (i = 0; i < num_user_hostfiles; i++)
723: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
724: for (i = 0; i < num_system_hostfiles; i++)
725: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 726:
727: ip_hostkeys = NULL;
728: if (!want_cert && options.check_host_ip) {
729: ip_hostkeys = init_hostkeys();
1.234 djm 730: for (i = 0; i < num_user_hostfiles; i++)
731: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
732: for (i = 0; i < num_system_hostfiles; i++)
733: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 734: }
1.38 markus 735:
1.219 djm 736: retry:
1.229 djm 737: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 738: want_cert = sshkey_is_cert(host_key);
739: type = sshkey_type(host_key);
1.219 djm 740:
1.46 markus 741: /*
1.170 djm 742: * Check if the host key is present in the user's list of known
1.40 markus 743: * hosts or in the systemwide list.
744: */
1.229 djm 745: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
746: &host_found);
747:
1.40 markus 748: /*
749: * Also perform check for the ip address, skip the check if we are
1.219 djm 750: * localhost, looking for a certificate, or the hostname was an ip
751: * address to begin with.
1.40 markus 752: */
1.229 djm 753: if (!want_cert && ip_hostkeys != NULL) {
754: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
755: &ip_found);
1.38 markus 756: if (host_status == HOST_CHANGED &&
1.319 ! djm 757: (ip_status != HOST_CHANGED ||
1.229 djm 758: (ip_found != NULL &&
1.280 markus 759: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 760: host_ip_differ = 1;
761: } else
762: ip_status = host_status;
763:
764: switch (host_status) {
765: case HOST_OK:
766: /* The host is known and the key matches. */
1.219 djm 767: debug("Host '%.200s' is known and matches the %s host %s.",
768: host, type, want_cert ? "certificate" : "key");
1.229 djm 769: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
770: host_found->file, host_found->line);
1.281 djm 771: if (want_cert &&
772: !check_host_cert(options.host_key_alias == NULL ?
773: hostname : options.host_key_alias, host_key))
1.219 djm 774: goto fail;
1.88 markus 775: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 776: if (readonly || want_cert)
1.138 itojun 777: logit("%s host key for IP address "
1.108 markus 778: "'%.128s' not in list of known hosts.",
779: type, ip);
1.234 djm 780: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 781: host_key, options.hash_known_hosts))
1.138 itojun 782: logit("Failed to add the %s host key for IP "
1.108 markus 783: "address '%.128s' to the list of known "
1.262 dtucker 784: "hosts (%.500s).", type, ip,
1.234 djm 785: user_hostfiles[0]);
1.88 markus 786: else
1.138 itojun 787: logit("Warning: Permanently added the %s host "
1.108 markus 788: "key for IP address '%.128s' to the list "
789: "of known hosts.", type, ip);
1.209 grunk 790: } else if (options.visual_host_key) {
1.259 djm 791: fp = sshkey_fingerprint(host_key,
1.254 djm 792: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 793: ra = sshkey_fingerprint(host_key,
1.254 djm 794: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 795: if (fp == NULL || ra == NULL)
796: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 797: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 798: free(ra);
799: free(fp);
1.38 markus 800: }
1.257 djm 801: hostkey_trusted = 1;
1.38 markus 802: break;
803: case HOST_NEW:
1.197 dtucker 804: if (options.host_key_alias == NULL && port != 0 &&
805: port != SSH_DEFAULT_PORT) {
806: debug("checking without port identifier");
1.212 stevesk 807: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 808: ROQUIET, user_hostfiles, num_user_hostfiles,
809: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 810: debug("found matching key w/out port");
811: break;
812: }
813: }
1.219 djm 814: if (readonly || want_cert)
1.108 markus 815: goto fail;
1.38 markus 816: /* The host is new. */
1.285 djm 817: if (options.strict_host_key_checking ==
818: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 819: /*
820: * User has requested strict host key checking. We
821: * will not add the host key automatically. The only
822: * alternative left is to abort.
823: */
824: error("No %s host key is known for %.200s and you "
825: "have requested strict checking.", type, host);
826: goto fail;
1.285 djm 827: } else if (options.strict_host_key_checking ==
828: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 829: char msg1[1024], msg2[1024];
830:
1.229 djm 831: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 832: snprintf(msg1, sizeof(msg1),
1.168 djm 833: "\nbut keys of different type are already"
834: " known for this host.");
1.145 jakob 835: else
836: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 837: /* The default */
1.259 djm 838: fp = sshkey_fingerprint(host_key,
1.254 djm 839: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 840: ra = sshkey_fingerprint(host_key,
1.254 djm 841: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 842: if (fp == NULL || ra == NULL)
843: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 844: msg2[0] = '\0';
845: if (options.verify_host_key_dns) {
1.153 jakob 846: if (matching_host_key_dns)
1.145 jakob 847: snprintf(msg2, sizeof(msg2),
848: "Matching host key fingerprint"
849: " found in DNS.\n");
850: else
851: snprintf(msg2, sizeof(msg2),
852: "No matching host key fingerprint"
853: " found in DNS.\n");
854: }
1.119 markus 855: snprintf(msg, sizeof(msg),
1.108 markus 856: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 857: "established%s\n"
1.209 grunk 858: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 859: "Are you sure you want to continue connecting "
1.312 dtucker 860: "(yes/no/[fingerprint])? ",
1.209 grunk 861: host, ip, msg1, type, fp,
862: options.visual_host_key ? "\n" : "",
863: options.visual_host_key ? ra : "",
864: msg2);
1.238 djm 865: free(ra);
1.312 dtucker 866: confirmed = confirm(msg, fp);
1.238 djm 867: free(fp);
1.312 dtucker 868: if (!confirmed)
1.108 markus 869: goto fail;
1.257 djm 870: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 871: }
1.161 djm 872: /*
1.285 djm 873: * If in "new" or "off" strict mode, add the key automatically
874: * to the local known_hosts file.
1.161 djm 875: */
1.88 markus 876: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 877: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 878: hostp = hostline;
1.161 djm 879: if (options.hash_known_hosts) {
880: /* Add hash of host and IP separately */
1.234 djm 881: r = add_host_to_hostfile(user_hostfiles[0],
882: host, host_key, options.hash_known_hosts) &&
883: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 884: host_key, options.hash_known_hosts);
885: } else {
886: /* Add unhashed "host,ip" */
1.234 djm 887: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 888: hostline, host_key,
889: options.hash_known_hosts);
890: }
891: } else {
1.234 djm 892: r = add_host_to_hostfile(user_hostfiles[0], host,
893: host_key, options.hash_known_hosts);
1.38 markus 894: hostp = host;
1.161 djm 895: }
1.38 markus 896:
1.161 djm 897: if (!r)
1.138 itojun 898: logit("Failed to add the host to the list of known "
1.234 djm 899: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 900: else
1.138 itojun 901: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 902: "list of known hosts.", hostp, type);
1.38 markus 903: break;
1.220 djm 904: case HOST_REVOKED:
905: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
906: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
907: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
908: error("The %s host key for %s is marked as revoked.", type, host);
909: error("This could mean that a stolen key is being used to");
910: error("impersonate this host.");
911:
912: /*
913: * If strict host key checking is in use, the user will have
914: * to edit the key manually and we can only abort.
915: */
1.285 djm 916: if (options.strict_host_key_checking !=
917: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 918: error("%s host key for %.200s was revoked and you have "
919: "requested strict checking.", type, host);
920: goto fail;
921: }
922: goto continue_unsafe;
923:
1.38 markus 924: case HOST_CHANGED:
1.219 djm 925: if (want_cert) {
926: /*
927: * This is only a debug() since it is valid to have
928: * CAs with wildcard DNS matches that don't match
929: * all hosts that one might visit.
930: */
931: debug("Host certificate authority does not "
1.229 djm 932: "match %s in %s:%lu", CA_MARKER,
933: host_found->file, host_found->line);
1.219 djm 934: goto fail;
935: }
1.197 dtucker 936: if (readonly == ROQUIET)
937: goto fail;
1.38 markus 938: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 939: char *key_msg;
1.38 markus 940: if (ip_status == HOST_NEW)
1.158 avsm 941: key_msg = "is unknown";
1.38 markus 942: else if (ip_status == HOST_OK)
1.158 avsm 943: key_msg = "is unchanged";
1.38 markus 944: else
1.158 avsm 945: key_msg = "has a different value";
1.38 markus 946: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
947: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
948: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 949: error("The %s host key for %s has changed,", type, host);
1.208 ian 950: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 951: error("%s. This could either mean that", key_msg);
1.38 markus 952: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 953: error("and its host key have changed at the same time.");
1.88 markus 954: if (ip_status != HOST_NEW)
1.229 djm 955: error("Offending key for IP in %s:%lu",
956: ip_found->file, ip_found->line);
1.38 markus 957: }
958: /* The host key has changed. */
1.150 jakob 959: warn_changed_key(host_key);
1.38 markus 960: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 961: user_hostfiles[0]);
1.280 markus 962: error("Offending %s key in %s:%lu",
963: sshkey_type(host_found->key),
1.229 djm 964: host_found->file, host_found->line);
1.38 markus 965:
1.40 markus 966: /*
967: * If strict host key checking is in use, the user will have
968: * to edit the key manually and we can only abort.
969: */
1.285 djm 970: if (options.strict_host_key_checking !=
971: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 972: error("%s host key for %.200s has changed and you have "
973: "requested strict checking.", type, host);
974: goto fail;
975: }
1.38 markus 976:
1.220 djm 977: continue_unsafe:
1.40 markus 978: /*
979: * If strict host key checking has not been requested, allow
1.144 djm 980: * the connection but without MITM-able authentication or
1.194 stevesk 981: * forwarding.
1.40 markus 982: */
1.38 markus 983: if (options.password_authentication) {
1.108 markus 984: error("Password authentication is disabled to avoid "
985: "man-in-the-middle attacks.");
1.38 markus 986: options.password_authentication = 0;
1.210 dtucker 987: cancelled_forwarding = 1;
1.144 djm 988: }
989: if (options.kbd_interactive_authentication) {
990: error("Keyboard-interactive authentication is disabled"
991: " to avoid man-in-the-middle attacks.");
992: options.kbd_interactive_authentication = 0;
993: options.challenge_response_authentication = 0;
1.210 dtucker 994: cancelled_forwarding = 1;
1.144 djm 995: }
996: if (options.challenge_response_authentication) {
997: error("Challenge/response authentication is disabled"
998: " to avoid man-in-the-middle attacks.");
999: options.challenge_response_authentication = 0;
1.210 dtucker 1000: cancelled_forwarding = 1;
1.38 markus 1001: }
1002: if (options.forward_agent) {
1.108 markus 1003: error("Agent forwarding is disabled to avoid "
1004: "man-in-the-middle attacks.");
1.38 markus 1005: options.forward_agent = 0;
1.210 dtucker 1006: cancelled_forwarding = 1;
1.83 markus 1007: }
1008: if (options.forward_x11) {
1.108 markus 1009: error("X11 forwarding is disabled to avoid "
1010: "man-in-the-middle attacks.");
1.83 markus 1011: options.forward_x11 = 0;
1.210 dtucker 1012: cancelled_forwarding = 1;
1.83 markus 1013: }
1.108 markus 1014: if (options.num_local_forwards > 0 ||
1015: options.num_remote_forwards > 0) {
1016: error("Port forwarding is disabled to avoid "
1017: "man-in-the-middle attacks.");
1018: options.num_local_forwards =
1.118 deraadt 1019: options.num_remote_forwards = 0;
1.210 dtucker 1020: cancelled_forwarding = 1;
1.194 stevesk 1021: }
1022: if (options.tun_open != SSH_TUNMODE_NO) {
1023: error("Tunnel forwarding is disabled to avoid "
1024: "man-in-the-middle attacks.");
1025: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1026: cancelled_forwarding = 1;
1.38 markus 1027: }
1.210 dtucker 1028: if (options.exit_on_forward_failure && cancelled_forwarding)
1029: fatal("Error: forwarding disabled due to host key "
1030: "check failure");
1031:
1.40 markus 1032: /*
1033: * XXX Should permit the user to change to use the new id.
1034: * This could be done by converting the host key to an
1035: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1036: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1037: * accept the authentication.
1038: */
1.38 markus 1039: break;
1.132 markus 1040: case HOST_FOUND:
1041: fatal("internal error");
1042: break;
1.88 markus 1043: }
1044:
1045: if (options.check_host_ip && host_status != HOST_CHANGED &&
1046: ip_status == HOST_CHANGED) {
1.119 markus 1047: snprintf(msg, sizeof(msg),
1048: "Warning: the %s host key for '%.200s' "
1049: "differs from the key for the IP address '%.128s'"
1.229 djm 1050: "\nOffending key for IP in %s:%lu",
1051: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1052: if (host_status == HOST_OK) {
1053: len = strlen(msg);
1054: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1055: "\nMatching host key in %s:%lu",
1056: host_found->file, host_found->line);
1.119 markus 1057: }
1.285 djm 1058: if (options.strict_host_key_checking ==
1059: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1060: strlcat(msg, "\nAre you sure you want "
1061: "to continue connecting (yes/no)? ", sizeof(msg));
1.312 dtucker 1062: if (!confirm(msg, NULL))
1.108 markus 1063: goto fail;
1.285 djm 1064: } else if (options.strict_host_key_checking !=
1065: SSH_STRICT_HOSTKEY_OFF) {
1066: logit("%s", msg);
1067: error("Exiting, you have requested strict checking.");
1068: goto fail;
1.119 markus 1069: } else {
1.143 djm 1070: logit("%s", msg);
1.88 markus 1071: }
1.257 djm 1072: }
1073:
1074: if (!hostkey_trusted && options.update_hostkeys) {
1075: debug("%s: hostkey not known or explicitly trusted: "
1076: "disabling UpdateHostkeys", __func__);
1077: options.update_hostkeys = 0;
1.38 markus 1078: }
1.82 provos 1079:
1.238 djm 1080: free(ip);
1081: free(host);
1.229 djm 1082: if (host_hostkeys != NULL)
1083: free_hostkeys(host_hostkeys);
1084: if (ip_hostkeys != NULL)
1085: free_hostkeys(ip_hostkeys);
1.108 markus 1086: return 0;
1087:
1088: fail:
1.220 djm 1089: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1090: /*
1091: * No matching certificate. Downgrade cert to raw key and
1092: * search normally.
1093: */
1094: debug("No matching CA found. Retry with plain key");
1.280 markus 1095: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1096: fatal("%s: sshkey_from_private: %s",
1097: __func__, ssh_err(r));
1098: if ((r = sshkey_drop_cert(raw_key)) != 0)
1099: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1100: host_key = raw_key;
1101: goto retry;
1102: }
1.293 dtucker 1103: sshkey_free(raw_key);
1.238 djm 1104: free(ip);
1105: free(host);
1.229 djm 1106: if (host_hostkeys != NULL)
1107: free_hostkeys(host_hostkeys);
1108: if (ip_hostkeys != NULL)
1109: free_hostkeys(ip_hostkeys);
1.108 markus 1110: return -1;
1111: }
1112:
1.140 jakob 1113: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1114: int
1.279 markus 1115: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1116: {
1.267 djm 1117: u_int i;
1.250 djm 1118: int r = -1, flags = 0;
1.267 djm 1119: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1120: struct sshkey *plain = NULL;
1.229 djm 1121:
1.252 djm 1122: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1123: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1124: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1125: r = -1;
1126: goto out;
1127: }
1128:
1.267 djm 1129: if (sshkey_is_cert(host_key)) {
1130: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1131: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1132: error("%s: fingerprint CA key: %s",
1133: __func__, ssh_err(r));
1134: r = -1;
1135: goto out;
1136: }
1137: sshkey_format_cert_validity(host_key->cert,
1138: valid, sizeof(valid));
1139: debug("Server host certificate: %s %s, serial %llu "
1140: "ID \"%s\" CA %s %s valid %s",
1141: sshkey_ssh_name(host_key), fp,
1.269 djm 1142: (unsigned long long)host_key->cert->serial,
1143: host_key->cert->key_id,
1.267 djm 1144: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1145: valid);
1146: for (i = 0; i < host_key->cert->nprincipals; i++) {
1147: debug2("Server host certificate hostname: %s",
1148: host_key->cert->principals[i]);
1149: }
1150: } else {
1.276 djm 1151: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1152: }
1.252 djm 1153:
1154: if (sshkey_equal(previous_host_key, host_key)) {
1155: debug2("%s: server host key %s %s matches cached key",
1156: __func__, sshkey_type(host_key), fp);
1157: r = 0;
1158: goto out;
1159: }
1160:
1161: /* Check in RevokedHostKeys file if specified */
1162: if (options.revoked_host_keys != NULL) {
1163: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1164: switch (r) {
1165: case 0:
1166: break; /* not revoked */
1167: case SSH_ERR_KEY_REVOKED:
1168: error("Host key %s %s revoked by file %s",
1169: sshkey_type(host_key), fp,
1170: options.revoked_host_keys);
1171: r = -1;
1172: goto out;
1173: default:
1174: error("Error checking host key %s %s in "
1175: "revoked keys file %s: %s", sshkey_type(host_key),
1176: fp, options.revoked_host_keys, ssh_err(r));
1177: r = -1;
1178: goto out;
1179: }
1.250 djm 1180: }
1181:
1.247 djm 1182: if (options.verify_host_key_dns) {
1183: /*
1184: * XXX certs are not yet supported for DNS, so downgrade
1185: * them and try the plain key.
1186: */
1.252 djm 1187: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1188: goto out;
1189: if (sshkey_is_cert(plain))
1190: sshkey_drop_cert(plain);
1.247 djm 1191: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1192: if (flags & DNS_VERIFY_FOUND) {
1193: if (options.verify_host_key_dns == 1 &&
1194: flags & DNS_VERIFY_MATCH &&
1195: flags & DNS_VERIFY_SECURE) {
1.250 djm 1196: r = 0;
1.252 djm 1197: goto out;
1.247 djm 1198: }
1199: if (flags & DNS_VERIFY_MATCH) {
1200: matching_host_key_dns = 1;
1201: } else {
1.287 djm 1202: warn_changed_key(plain);
1203: error("Update the SSHFP RR in DNS "
1204: "with the new host key to get rid "
1205: "of this message.");
1.247 djm 1206: }
1.153 jakob 1207: }
1.140 jakob 1208: }
1209: }
1.250 djm 1210: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1211: options.user_hostfiles, options.num_user_hostfiles,
1212: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1213:
1.252 djm 1214: out:
1215: sshkey_free(plain);
1216: free(fp);
1.267 djm 1217: free(cafp);
1.250 djm 1218: if (r == 0 && host_key != NULL) {
1.280 markus 1219: sshkey_free(previous_host_key);
1220: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1221: }
1222:
1223: return r;
1.51 markus 1224: }
1.70 markus 1225:
1.51 markus 1226: /*
1227: * Starts a dialog with the server, and authenticates the current user on the
1228: * server. This does not need any extra privileges. The basic connection
1229: * to the server must already have been established before this is called.
1230: * If login fails, this function prints an error and never returns.
1231: * This function does not require super-user privileges.
1232: */
1233: void
1.309 djm 1234: ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost,
1.229 djm 1235: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1236: {
1.241 djm 1237: char *host;
1.70 markus 1238: char *server_user, *local_user;
1239:
1240: local_user = xstrdup(pw->pw_name);
1241: server_user = options.user ? options.user : local_user;
1.51 markus 1242:
1243: /* Convert the user-supplied hostname into all lowercase. */
1244: host = xstrdup(orighost);
1.241 djm 1245: lowercase(host);
1.51 markus 1246:
1247: /* Exchange protocol version identification strings with the server. */
1.309 djm 1248: if (kex_exchange_identification(ssh, timeout_ms, NULL) != 0)
1249: cleanup_exit(255); /* error already logged */
1.51 markus 1250:
1251: /* Put the connection into non-blocking mode. */
1.309 djm 1252: ssh_packet_set_nonblocking(ssh);
1.51 markus 1253:
1254: /* key exchange */
1255: /* authenticate user */
1.261 dtucker 1256: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.309 djm 1257: ssh_kex2(ssh, host, hostaddr, port);
1258: ssh_userauth2(ssh, local_user, server_user, host, sensitive);
1.238 djm 1259: free(local_user);
1.315 dtucker 1260: free(host);
1.132 markus 1261: }
1262:
1263: /* print all known host keys for a given host, but skip keys of given type */
1264: static int
1.279 markus 1265: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1266: {
1.242 djm 1267: int type[] = {
1268: KEY_RSA,
1269: KEY_DSA,
1270: KEY_ECDSA,
1271: KEY_ED25519,
1.297 markus 1272: KEY_XMSS,
1.242 djm 1273: -1
1274: };
1.229 djm 1275: int i, ret = 0;
1276: char *fp, *ra;
1277: const struct hostkey_entry *found;
1.132 markus 1278:
1279: for (i = 0; type[i] != -1; i++) {
1280: if (type[i] == key->type)
1281: continue;
1.229 djm 1282: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1283: continue;
1.259 djm 1284: fp = sshkey_fingerprint(found->key,
1.254 djm 1285: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1286: ra = sshkey_fingerprint(found->key,
1.254 djm 1287: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1288: if (fp == NULL || ra == NULL)
1289: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1290: logit("WARNING: %s key found for host %s\n"
1291: "in %s:%lu\n"
1292: "%s key fingerprint %s.",
1.300 markus 1293: sshkey_type(found->key),
1.229 djm 1294: found->host, found->file, found->line,
1.300 markus 1295: sshkey_type(found->key), fp);
1.229 djm 1296: if (options.visual_host_key)
1297: logit("%s", ra);
1.238 djm 1298: free(ra);
1299: free(fp);
1.229 djm 1300: ret = 1;
1.132 markus 1301: }
1.229 djm 1302: return ret;
1.150 jakob 1303: }
1304:
1305: static void
1.279 markus 1306: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1307: {
1308: char *fp;
1309:
1.259 djm 1310: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1311: SSH_FP_DEFAULT);
1.259 djm 1312: if (fp == NULL)
1313: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1314:
1315: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1316: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1317: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1318: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1319: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1320: error("It is also possible that a host key has just been changed.");
1.150 jakob 1321: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.300 markus 1322: sshkey_type(host_key), fp);
1.150 jakob 1323: error("Please contact your system administrator.");
1324:
1.238 djm 1325: free(fp);
1.171 reyk 1326: }
1327:
1328: /*
1329: * Execute a local command
1330: */
1331: int
1332: ssh_local_cmd(const char *args)
1333: {
1334: char *shell;
1335: pid_t pid;
1336: int status;
1.231 djm 1337: void (*osighand)(int);
1.171 reyk 1338:
1339: if (!options.permit_local_command ||
1340: args == NULL || !*args)
1341: return (1);
1342:
1.226 djm 1343: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1344: shell = _PATH_BSHELL;
1345:
1.231 djm 1346: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1347: pid = fork();
1348: if (pid == 0) {
1.232 djm 1349: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1350: debug3("Executing %s -c \"%s\"", shell, args);
1351: execl(shell, shell, "-c", args, (char *)NULL);
1352: error("Couldn't execute %s -c \"%s\": %s",
1353: shell, args, strerror(errno));
1354: _exit(1);
1355: } else if (pid == -1)
1356: fatal("fork failed: %.100s", strerror(errno));
1357: while (waitpid(pid, &status, 0) == -1)
1358: if (errno != EINTR)
1359: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1360: signal(SIGCHLD, osighand);
1.171 reyk 1361:
1362: if (!WIFEXITED(status))
1363: return (1);
1364:
1365: return (WEXITSTATUS(status));
1.266 jcs 1366: }
1367:
1368: void
1.316 djm 1369: maybe_add_key_to_agent(char *authfile, struct sshkey *private,
1.294 djm 1370: char *comment, char *passphrase)
1.266 jcs 1371: {
1372: int auth_sock = -1, r;
1373:
1374: if (options.add_keys_to_agent == 0)
1375: return;
1376:
1377: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1378: debug3("no authentication agent, not adding key");
1379: return;
1380: }
1381:
1382: if (options.add_keys_to_agent == 2 &&
1383: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1384: debug3("user denied adding this key");
1.273 dtucker 1385: close(auth_sock);
1.266 jcs 1386: return;
1387: }
1388:
1389: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1.297 markus 1390: (options.add_keys_to_agent == 3), 0)) == 0)
1.266 jcs 1391: debug("identity added to agent: %s", authfile);
1392: else
1393: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1394: close(auth_sock);
1.1 deraadt 1395: }
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