Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.326
1.326 ! dtucker 1: /* $OpenBSD: sshconnect.c,v 1.325 2020/01/11 16:23:10 naddy 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];
80:
1.241 djm 81: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 82: xasprintf(&tmp, "exec %s", proxy_command);
1.318 djm 83: ret = percent_expand(tmp,
84: "h", host,
85: "n", host_arg,
86: "p", strport,
87: "r", options.user,
88: (char *)NULL);
1.239 djm 89: free(tmp);
90: return ret;
91: }
92:
1.307 djm 93: static void
94: stderr_null(void)
95: {
96: int devnull;
97:
98: if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1) {
99: error("Can't open %s for stderr redirection: %s",
100: _PATH_DEVNULL, strerror(errno));
101: return;
102: }
103: if (devnull == STDERR_FILENO)
104: return;
105: if (dup2(devnull, STDERR_FILENO) == -1)
106: error("Cannot redirect stderr to %s", _PATH_DEVNULL);
107: if (devnull > STDERR_FILENO)
108: close(devnull);
109: }
110:
1.239 djm 111: /*
112: * Connect to the given ssh server using a proxy command that passes a
113: * a connected fd back to us.
114: */
115: static int
1.318 djm 116: ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host,
117: const char *host_arg, u_short port, const char *proxy_command)
1.239 djm 118: {
119: char *command_string;
120: int sp[2], sock;
121: pid_t pid;
122: char *shell;
123:
124: if ((shell = getenv("SHELL")) == NULL)
125: shell = _PATH_BSHELL;
126:
1.317 deraadt 127: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) == -1)
1.239 djm 128: fatal("Could not create socketpair to communicate with "
129: "proxy dialer: %.100s", strerror(errno));
130:
131: command_string = expand_proxy_command(proxy_command, options.user,
1.325 naddy 132: host, host_arg, port);
1.239 djm 133: debug("Executing proxy dialer command: %.500s", command_string);
134:
135: /* Fork and execute the proxy command. */
136: if ((pid = fork()) == 0) {
137: char *argv[10];
138:
139: close(sp[1]);
140: /* Redirect stdin and stdout. */
141: if (sp[0] != 0) {
1.317 deraadt 142: if (dup2(sp[0], 0) == -1)
1.239 djm 143: perror("dup2 stdin");
144: }
145: if (sp[0] != 1) {
1.317 deraadt 146: if (dup2(sp[0], 1) == -1)
1.239 djm 147: perror("dup2 stdout");
148: }
149: if (sp[0] >= 2)
150: close(sp[0]);
151:
152: /*
1.307 djm 153: * Stderr is left for non-ControlPersist connections is so
154: * error messages may be printed on the user's terminal.
1.239 djm 155: */
1.308 dtucker 156: if (!debug_flag && options.control_path != NULL &&
157: options.control_persist)
1.307 djm 158: stderr_null();
159:
1.239 djm 160: argv[0] = shell;
161: argv[1] = "-c";
162: argv[2] = command_string;
163: argv[3] = NULL;
164:
165: /*
166: * Execute the proxy command.
167: * Note that we gave up any extra privileges above.
168: */
169: execv(argv[0], argv);
170: perror(argv[0]);
171: exit(1);
172: }
173: /* Parent. */
1.317 deraadt 174: if (pid == -1)
1.239 djm 175: fatal("fork failed: %.100s", strerror(errno));
176: close(sp[0]);
177: free(command_string);
178:
179: if ((sock = mm_receive_fd(sp[1])) == -1)
180: fatal("proxy dialer did not pass back a connection");
1.271 markus 181: close(sp[1]);
1.239 djm 182:
183: while (waitpid(pid, NULL, 0) == -1)
184: if (errno != EINTR)
185: fatal("Couldn't wait for child: %s", strerror(errno));
186:
187: /* Set the connection file descriptors. */
1.286 djm 188: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
189: return -1; /* ssh_packet_set_connection logs error */
1.239 djm 190:
191: return 0;
192: }
193:
1.39 deraadt 194: /*
195: * Connect to the given ssh server using a proxy command.
196: */
1.109 itojun 197: static int
1.318 djm 198: ssh_proxy_connect(struct ssh *ssh, const char *host, const char *host_arg,
199: u_short port, const char *proxy_command)
1.1 deraadt 200: {
1.239 djm 201: char *command_string;
1.38 markus 202: int pin[2], pout[2];
1.69 deraadt 203: pid_t pid;
1.239 djm 204: char *shell;
1.237 markus 205:
1.226 djm 206: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 207: shell = _PATH_BSHELL;
1.38 markus 208:
209: /* Create pipes for communicating with the proxy. */
1.317 deraadt 210: if (pipe(pin) == -1 || pipe(pout) == -1)
1.38 markus 211: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 212: strerror(errno));
1.38 markus 213:
1.239 djm 214: command_string = expand_proxy_command(proxy_command, options.user,
1.325 naddy 215: host, host_arg, port);
1.38 markus 216: debug("Executing proxy command: %.500s", command_string);
217:
218: /* Fork and execute the proxy command. */
219: if ((pid = fork()) == 0) {
220: char *argv[10];
221:
222: /* Redirect stdin and stdout. */
223: close(pin[1]);
224: if (pin[0] != 0) {
1.317 deraadt 225: if (dup2(pin[0], 0) == -1)
1.38 markus 226: perror("dup2 stdin");
227: close(pin[0]);
228: }
229: close(pout[0]);
1.317 deraadt 230: if (dup2(pout[1], 1) == -1)
1.38 markus 231: perror("dup2 stdout");
232: /* Cannot be 1 because pin allocated two descriptors. */
233: close(pout[1]);
234:
1.307 djm 235: /*
236: * Stderr is left for non-ControlPersist connections is so
237: * error messages may be printed on the user's terminal.
238: */
1.308 dtucker 239: if (!debug_flag && options.control_path != NULL &&
240: options.control_persist)
1.307 djm 241: stderr_null();
242:
1.201 djm 243: argv[0] = shell;
1.38 markus 244: argv[1] = "-c";
245: argv[2] = command_string;
246: argv[3] = NULL;
247:
248: /* Execute the proxy command. Note that we gave up any
249: extra privileges above. */
1.232 djm 250: signal(SIGPIPE, SIG_DFL);
1.89 markus 251: execv(argv[0], argv);
252: perror(argv[0]);
1.38 markus 253: exit(1);
254: }
255: /* Parent. */
1.317 deraadt 256: if (pid == -1)
1.38 markus 257: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 258: else
259: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 260:
261: /* Close child side of the descriptors. */
262: close(pin[0]);
263: close(pout[1]);
264:
265: /* Free the command name. */
1.238 djm 266: free(command_string);
1.38 markus 267:
268: /* Set the connection file descriptors. */
1.286 djm 269: if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
270: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 271:
1.110 markus 272: return 0;
1.227 djm 273: }
274:
275: void
276: ssh_kill_proxy_command(void)
277: {
278: /*
279: * Send SIGHUP to proxy command if used. We don't wait() in
280: * case it hangs and instead rely on init to reap the child
281: */
282: if (proxy_command_pid > 1)
1.228 djm 283: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 284: }
285:
1.39 deraadt 286: /*
1.295 djm 287: * Search a interface address list (returned from getifaddrs(3)) for an
1.298 djm 288: * address that matches the desired address family on the specified interface.
1.295 djm 289: * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure.
290: */
291: static int
292: check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs,
293: struct sockaddr_storage *resultp, socklen_t *rlenp)
294: {
295: struct sockaddr_in6 *sa6;
296: struct sockaddr_in *sa;
297: struct in6_addr *v6addr;
298: const struct ifaddrs *ifa;
299: int allow_local;
300:
301: /*
302: * Prefer addresses that are not loopback or linklocal, but use them
303: * if nothing else matches.
304: */
305: for (allow_local = 0; allow_local < 2; allow_local++) {
306: for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
307: if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL ||
308: (ifa->ifa_flags & IFF_UP) == 0 ||
309: ifa->ifa_addr->sa_family != af ||
310: strcmp(ifa->ifa_name, options.bind_interface) != 0)
311: continue;
312: switch (ifa->ifa_addr->sa_family) {
313: case AF_INET:
314: sa = (struct sockaddr_in *)ifa->ifa_addr;
315: if (!allow_local && sa->sin_addr.s_addr ==
316: htonl(INADDR_LOOPBACK))
317: continue;
318: if (*rlenp < sizeof(struct sockaddr_in)) {
319: error("%s: v4 addr doesn't fit",
320: __func__);
321: return -1;
322: }
323: *rlenp = sizeof(struct sockaddr_in);
324: memcpy(resultp, sa, *rlenp);
325: return 0;
326: case AF_INET6:
327: sa6 = (struct sockaddr_in6 *)ifa->ifa_addr;
328: v6addr = &sa6->sin6_addr;
329: if (!allow_local &&
330: (IN6_IS_ADDR_LINKLOCAL(v6addr) ||
331: IN6_IS_ADDR_LOOPBACK(v6addr)))
332: continue;
333: if (*rlenp < sizeof(struct sockaddr_in6)) {
334: error("%s: v6 addr doesn't fit",
335: __func__);
336: return -1;
337: }
338: *rlenp = sizeof(struct sockaddr_in6);
339: memcpy(resultp, sa6, *rlenp);
340: return 0;
341: }
342: }
343: }
344: return -1;
345: }
346:
347: /*
1.303 dtucker 348: * Creates a socket for use as the ssh connection.
1.39 deraadt 349: */
1.109 itojun 350: static int
1.302 dtucker 351: ssh_create_socket(struct addrinfo *ai)
1.1 deraadt 352: {
1.301 dtucker 353: int sock, r;
1.295 djm 354: struct sockaddr_storage bindaddr;
355: socklen_t bindaddrlen = 0;
1.246 djm 356: struct addrinfo hints, *res = NULL;
1.295 djm 357: struct ifaddrs *ifaddrs = NULL;
358: char ntop[NI_MAXHOST];
1.1 deraadt 359:
1.217 dtucker 360: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.317 deraadt 361: if (sock == -1) {
1.240 djm 362: error("socket: %s", strerror(errno));
1.216 dtucker 363: return -1;
364: }
365: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 366:
367: /* Bind the socket to an alternative local IP address */
1.302 dtucker 368: if (options.bind_address == NULL && options.bind_interface == NULL)
1.105 markus 369: return sock;
370:
1.295 djm 371: if (options.bind_address != NULL) {
1.246 djm 372: memset(&hints, 0, sizeof(hints));
373: hints.ai_family = ai->ai_family;
374: hints.ai_socktype = ai->ai_socktype;
375: hints.ai_protocol = ai->ai_protocol;
376: hints.ai_flags = AI_PASSIVE;
1.295 djm 377: if ((r = getaddrinfo(options.bind_address, NULL,
378: &hints, &res)) != 0) {
1.246 djm 379: error("getaddrinfo: %s: %s", options.bind_address,
1.295 djm 380: ssh_gai_strerror(r));
381: goto fail;
382: }
1.296 dtucker 383: if (res == NULL) {
1.295 djm 384: error("getaddrinfo: no addrs");
385: goto fail;
386: }
387: memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
388: bindaddrlen = res->ai_addrlen;
389: } else if (options.bind_interface != NULL) {
390: if ((r = getifaddrs(&ifaddrs)) != 0) {
391: error("getifaddrs: %s: %s", options.bind_interface,
392: strerror(errno));
393: goto fail;
394: }
395: bindaddrlen = sizeof(bindaddr);
396: if (check_ifaddrs(options.bind_interface, ai->ai_family,
397: ifaddrs, &bindaddr, &bindaddrlen) != 0) {
398: logit("getifaddrs: %s: no suitable addresses",
399: options.bind_interface);
400: goto fail;
1.246 djm 401: }
1.105 markus 402: }
1.295 djm 403: if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
404: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
405: error("%s: getnameinfo failed: %s", __func__,
406: ssh_gai_strerror(r));
407: goto fail;
408: }
1.301 dtucker 409: if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
1.295 djm 410: error("bind %s: %s", ntop, strerror(errno));
411: goto fail;
1.38 markus 412: }
1.295 djm 413: debug("%s: bound to %s", __func__, ntop);
414: /* success */
415: goto out;
416: fail:
417: close(sock);
418: sock = -1;
419: out:
1.246 djm 420: if (res != NULL)
421: freeaddrinfo(res);
1.295 djm 422: if (ifaddrs != NULL)
423: freeifaddrs(ifaddrs);
1.38 markus 424: return sock;
1.1 deraadt 425: }
426:
1.282 djm 427: /*
1.49 markus 428: * Opens a TCP/IP connection to the remote server on the given host.
429: * The address of the remote host will be returned in hostaddr.
1.302 dtucker 430: * If port is 0, the default port will be used.
1.39 deraadt 431: * Connection_attempts specifies the maximum number of tries (one per
432: * second). If proxy_command is non-NULL, it specifies the command (with %h
433: * and %p substituted for host and port, respectively) to use to contact
434: * the daemon.
435: */
1.241 djm 436: static int
1.286 djm 437: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.241 djm 438: struct sockaddr_storage *hostaddr, u_short port, int family,
1.302 dtucker 439: int connection_attempts, int *timeout_ms, int want_keepalive)
1.1 deraadt 440: {
1.313 dtucker 441: int on = 1, saved_timeout_ms = *timeout_ms;
1.290 djm 442: int oerrno, sock = -1, attempt;
1.90 markus 443: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 444: struct addrinfo *ai;
1.38 markus 445:
1.302 dtucker 446: debug2("%s", __func__);
1.268 djm 447: memset(ntop, 0, sizeof(ntop));
448: memset(strport, 0, sizeof(strport));
1.38 markus 449:
1.181 markus 450: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 451: if (attempt > 0) {
452: /* Sleep a moment before retrying. */
453: sleep(1);
1.38 markus 454: debug("Trying again...");
1.200 markus 455: }
1.181 markus 456: /*
457: * Loop through addresses for this host, and try each one in
458: * sequence until the connection succeeds.
459: */
1.49 markus 460: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 461: if (ai->ai_family != AF_INET &&
1.290 djm 462: ai->ai_family != AF_INET6) {
463: errno = EAFNOSUPPORT;
1.49 markus 464: continue;
1.290 djm 465: }
1.49 markus 466: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
467: ntop, sizeof(ntop), strport, sizeof(strport),
468: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.290 djm 469: oerrno = errno;
1.265 djm 470: error("%s: getnameinfo failed", __func__);
1.290 djm 471: errno = oerrno;
1.49 markus 472: continue;
473: }
474: debug("Connecting to %.200s [%.100s] port %s.",
475: host, ntop, strport);
476:
477: /* Create a socket for connecting. */
1.302 dtucker 478: sock = ssh_create_socket(ai);
1.292 stsp 479: if (sock < 0) {
1.110 markus 480: /* Any error is already output */
1.290 djm 481: errno = 0;
1.49 markus 482: continue;
1.292 stsp 483: }
1.49 markus 484:
1.313 dtucker 485: *timeout_ms = saved_timeout_ms;
1.141 djm 486: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 487: timeout_ms) >= 0) {
1.49 markus 488: /* Successful connection. */
1.102 markus 489: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 490: break;
1.49 markus 491: } else {
1.290 djm 492: oerrno = errno;
1.131 itojun 493: debug("connect to address %s port %s: %s",
494: ntop, strport, strerror(errno));
1.38 markus 495: close(sock);
1.181 markus 496: sock = -1;
1.290 djm 497: errno = oerrno;
1.38 markus 498: }
499: }
1.181 markus 500: if (sock != -1)
1.49 markus 501: break; /* Successful connection. */
1.38 markus 502: }
1.49 markus 503:
1.38 markus 504: /* Return failure if we didn't get a successful connection. */
1.181 markus 505: if (sock == -1) {
1.159 markus 506: error("ssh: connect to host %s port %s: %s",
1.290 djm 507: host, strport, errno == 0 ? "failure" : strerror(errno));
508: return -1;
1.130 itojun 509: }
1.38 markus 510:
511: debug("Connection established.");
1.90 markus 512:
1.155 markus 513: /* Set SO_KEEPALIVE if requested. */
1.202 djm 514: if (want_keepalive &&
1.90 markus 515: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
1.317 deraadt 516: sizeof(on)) == -1)
1.90 markus 517: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 518:
519: /* Set the connection. */
1.286 djm 520: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
521: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 522:
1.319 djm 523: return 0;
1.59 markus 524: }
525:
1.241 djm 526: int
1.318 djm 527: ssh_connect(struct ssh *ssh, const char *host, const char *host_arg,
528: struct addrinfo *addrs, struct sockaddr_storage *hostaddr, u_short port,
529: int family, int connection_attempts, int *timeout_ms, int want_keepalive)
1.241 djm 530: {
1.314 markus 531: int in, out;
532:
1.241 djm 533: if (options.proxy_command == NULL) {
1.286 djm 534: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
1.302 dtucker 535: family, connection_attempts, timeout_ms, want_keepalive);
1.241 djm 536: } else if (strcmp(options.proxy_command, "-") == 0) {
1.317 deraadt 537: if ((in = dup(STDIN_FILENO)) == -1 ||
538: (out = dup(STDOUT_FILENO)) == -1) {
1.314 markus 539: if (in >= 0)
540: close(in);
541: error("%s: dup() in/out failed", __func__);
542: return -1; /* ssh_packet_set_connection logs error */
543: }
544: if ((ssh_packet_set_connection(ssh, in, out)) == NULL)
1.286 djm 545: return -1; /* ssh_packet_set_connection logs error */
546: return 0;
1.241 djm 547: } else if (options.proxy_use_fdpass) {
1.318 djm 548: return ssh_proxy_fdpass_connect(ssh, host, host_arg, port,
1.241 djm 549: options.proxy_command);
550: }
1.318 djm 551: return ssh_proxy_connect(ssh, host, host_arg, port,
552: options.proxy_command);
1.241 djm 553: }
554:
1.96 markus 555: /* defaults to 'no' */
1.109 itojun 556: static int
1.312 dtucker 557: confirm(const char *prompt, const char *fingerprint)
1.1 deraadt 558: {
1.119 markus 559: const char *msg, *again = "Please type 'yes' or 'no': ";
1.312 dtucker 560: const char *again_fp = "Please type 'yes', 'no' or the fingerprint: ";
1.326 ! dtucker 561: char *p, *cp;
1.119 markus 562: int ret = -1;
1.96 markus 563:
564: if (options.batch_mode)
565: return 0;
1.312 dtucker 566: for (msg = prompt;;msg = fingerprint ? again_fp : again) {
1.326 ! dtucker 567: cp = p = read_passphrase(msg, RP_ECHO);
1.289 djm 568: if (p == NULL)
569: return 0;
1.326 ! dtucker 570: p += strspn(p, " \t"); /* skip leading whitespace */
! 571: p[strcspn(p, " \t\n")] = '\0'; /* remove trailing whitespace */
1.289 djm 572: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 573: ret = 0;
1.312 dtucker 574: else if (strcasecmp(p, "yes") == 0 || (fingerprint != NULL &&
575: strcasecmp(p, fingerprint) == 0))
1.119 markus 576: ret = 1;
1.326 ! dtucker 577: free(cp);
1.119 markus 578: if (ret != -1)
579: return ret;
1.1 deraadt 580: }
581: }
582:
1.219 djm 583: static int
1.305 djm 584: check_host_cert(const char *host, const struct sshkey *key)
1.219 djm 585: {
586: const char *reason;
1.305 djm 587: int r;
1.219 djm 588:
1.305 djm 589: if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) {
1.219 djm 590: error("%s", reason);
591: return 0;
592: }
1.305 djm 593: if (sshbuf_len(key->cert->critical) != 0) {
1.223 djm 594: error("Certificate for %s contains unsupported "
595: "critical options(s)", host);
1.219 djm 596: return 0;
597: }
1.305 djm 598: if ((r = sshkey_check_cert_sigtype(key,
599: options.ca_sign_algorithms)) != 0) {
600: logit("%s: certificate signature algorithm %s: %s", __func__,
601: (key->cert == NULL || key->cert->signature_type == NULL) ?
602: "(null)" : key->cert->signature_type, ssh_err(r));
603: return 0;
604: }
605:
1.219 djm 606: return 1;
607: }
608:
1.229 djm 609: static int
610: sockaddr_is_local(struct sockaddr *hostaddr)
611: {
612: switch (hostaddr->sa_family) {
613: case AF_INET:
614: return (ntohl(((struct sockaddr_in *)hostaddr)->
615: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
616: case AF_INET6:
617: return IN6_IS_ADDR_LOOPBACK(
618: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
619: default:
620: return 0;
621: }
622: }
623:
624: /*
625: * Prepare the hostname and ip address strings that are used to lookup
626: * host keys in known_hosts files. These may have a port number appended.
627: */
628: void
629: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
630: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
631: {
632: char ntop[NI_MAXHOST];
633:
634: /*
635: * We don't have the remote ip-address for connections
636: * using a proxy command
637: */
638: if (hostfile_ipaddr != NULL) {
639: if (options.proxy_command == NULL) {
640: if (getnameinfo(hostaddr, hostaddr->sa_len,
641: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 642: fatal("%s: getnameinfo failed", __func__);
1.229 djm 643: *hostfile_ipaddr = put_host_port(ntop, port);
644: } else {
645: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
646: "command>");
647: }
648: }
649:
650: /*
651: * Allow the user to record the key under a different name or
652: * differentiate a non-standard port. This is useful for ssh
653: * tunneling over forwarded connections or if you run multiple
654: * sshd's on different ports on the same machine.
655: */
656: if (hostfile_hostname != NULL) {
657: if (options.host_key_alias != NULL) {
658: *hostfile_hostname = xstrdup(options.host_key_alias);
659: debug("using hostkeyalias: %s", *hostfile_hostname);
660: } else {
661: *hostfile_hostname = put_host_port(hostname, port);
662: }
663: }
664: }
665:
1.39 deraadt 666: /*
1.108 markus 667: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 668: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 669: */
1.197 dtucker 670: #define RDRW 0
671: #define RDONLY 1
672: #define ROQUIET 2
1.109 itojun 673: static int
1.197 dtucker 674: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 675: struct sshkey *host_key, int readonly,
1.234 djm 676: char **user_hostfiles, u_int num_user_hostfiles,
677: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 678: {
1.234 djm 679: HostStatus host_status;
680: HostStatus ip_status;
1.279 markus 681: struct sshkey *raw_key = NULL;
1.189 dtucker 682: char *ip = NULL, *host = NULL;
1.204 grunk 683: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 684: char msg[1024];
1.234 djm 685: const char *type;
686: const struct hostkey_entry *host_found, *ip_found;
1.312 dtucker 687: int len, cancelled_forwarding = 0, confirmed;
1.234 djm 688: int local = sockaddr_is_local(hostaddr);
1.280 markus 689: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 690: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 691: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 692: u_int i;
1.49 markus 693:
694: /*
695: * Force accepting of the host key for loopback/localhost. The
696: * problem is that if the home directory is NFS-mounted to multiple
697: * machines, localhost will refer to a different machine in each of
698: * them, and the user will get bogus HOST_CHANGED warnings. This
699: * essentially disables host authentication for localhost; however,
700: * this is probably not a real problem.
701: */
1.111 markus 702: if (options.no_host_authentication_for_localhost == 1 && local &&
703: options.host_key_alias == NULL) {
1.88 markus 704: debug("Forcing accepting of host key for "
705: "loopback/localhost.");
1.108 markus 706: return 0;
1.49 markus 707: }
1.42 markus 708:
709: /*
1.229 djm 710: * Prepare the hostname and address strings used for hostkey lookup.
711: * In some cases, these will have a port number appended.
1.42 markus 712: */
1.229 djm 713: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 714:
715: /*
1.88 markus 716: * Turn off check_host_ip if the connection is to localhost, via proxy
717: * command or if we don't have a hostname to compare with
718: */
1.189 dtucker 719: if (options.check_host_ip && (local ||
720: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 721: options.check_host_ip = 0;
1.86 markus 722:
1.229 djm 723: host_hostkeys = init_hostkeys();
1.234 djm 724: for (i = 0; i < num_user_hostfiles; i++)
725: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
726: for (i = 0; i < num_system_hostfiles; i++)
727: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 728:
729: ip_hostkeys = NULL;
730: if (!want_cert && options.check_host_ip) {
731: ip_hostkeys = init_hostkeys();
1.234 djm 732: for (i = 0; i < num_user_hostfiles; i++)
733: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
734: for (i = 0; i < num_system_hostfiles; i++)
735: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 736: }
1.38 markus 737:
1.219 djm 738: retry:
1.229 djm 739: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 740: want_cert = sshkey_is_cert(host_key);
741: type = sshkey_type(host_key);
1.219 djm 742:
1.46 markus 743: /*
1.170 djm 744: * Check if the host key is present in the user's list of known
1.40 markus 745: * hosts or in the systemwide list.
746: */
1.229 djm 747: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
748: &host_found);
749:
1.40 markus 750: /*
751: * Also perform check for the ip address, skip the check if we are
1.219 djm 752: * localhost, looking for a certificate, or the hostname was an ip
753: * address to begin with.
1.40 markus 754: */
1.229 djm 755: if (!want_cert && ip_hostkeys != NULL) {
756: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
757: &ip_found);
1.38 markus 758: if (host_status == HOST_CHANGED &&
1.319 djm 759: (ip_status != HOST_CHANGED ||
1.229 djm 760: (ip_found != NULL &&
1.280 markus 761: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 762: host_ip_differ = 1;
763: } else
764: ip_status = host_status;
765:
766: switch (host_status) {
767: case HOST_OK:
768: /* The host is known and the key matches. */
1.219 djm 769: debug("Host '%.200s' is known and matches the %s host %s.",
770: host, type, want_cert ? "certificate" : "key");
1.229 djm 771: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
772: host_found->file, host_found->line);
1.281 djm 773: if (want_cert &&
774: !check_host_cert(options.host_key_alias == NULL ?
775: hostname : options.host_key_alias, host_key))
1.219 djm 776: goto fail;
1.88 markus 777: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 778: if (readonly || want_cert)
1.138 itojun 779: logit("%s host key for IP address "
1.108 markus 780: "'%.128s' not in list of known hosts.",
781: type, ip);
1.234 djm 782: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 783: host_key, options.hash_known_hosts))
1.138 itojun 784: logit("Failed to add the %s host key for IP "
1.108 markus 785: "address '%.128s' to the list of known "
1.262 dtucker 786: "hosts (%.500s).", type, ip,
1.234 djm 787: user_hostfiles[0]);
1.88 markus 788: else
1.138 itojun 789: logit("Warning: Permanently added the %s host "
1.108 markus 790: "key for IP address '%.128s' to the list "
791: "of known hosts.", type, ip);
1.209 grunk 792: } else if (options.visual_host_key) {
1.259 djm 793: fp = sshkey_fingerprint(host_key,
1.254 djm 794: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 795: ra = sshkey_fingerprint(host_key,
1.254 djm 796: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 797: if (fp == NULL || ra == NULL)
798: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 799: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 800: free(ra);
801: free(fp);
1.38 markus 802: }
1.257 djm 803: hostkey_trusted = 1;
1.38 markus 804: break;
805: case HOST_NEW:
1.197 dtucker 806: if (options.host_key_alias == NULL && port != 0 &&
807: port != SSH_DEFAULT_PORT) {
808: debug("checking without port identifier");
1.212 stevesk 809: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 810: ROQUIET, user_hostfiles, num_user_hostfiles,
811: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 812: debug("found matching key w/out port");
813: break;
814: }
815: }
1.219 djm 816: if (readonly || want_cert)
1.108 markus 817: goto fail;
1.38 markus 818: /* The host is new. */
1.285 djm 819: if (options.strict_host_key_checking ==
820: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 821: /*
822: * User has requested strict host key checking. We
823: * will not add the host key automatically. The only
824: * alternative left is to abort.
825: */
826: error("No %s host key is known for %.200s and you "
827: "have requested strict checking.", type, host);
828: goto fail;
1.285 djm 829: } else if (options.strict_host_key_checking ==
830: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 831: char msg1[1024], msg2[1024];
832:
1.229 djm 833: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 834: snprintf(msg1, sizeof(msg1),
1.168 djm 835: "\nbut keys of different type are already"
836: " known for this host.");
1.145 jakob 837: else
838: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 839: /* The default */
1.259 djm 840: fp = sshkey_fingerprint(host_key,
1.254 djm 841: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 842: ra = sshkey_fingerprint(host_key,
1.254 djm 843: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 844: if (fp == NULL || ra == NULL)
845: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 846: msg2[0] = '\0';
847: if (options.verify_host_key_dns) {
1.153 jakob 848: if (matching_host_key_dns)
1.145 jakob 849: snprintf(msg2, sizeof(msg2),
850: "Matching host key fingerprint"
851: " found in DNS.\n");
852: else
853: snprintf(msg2, sizeof(msg2),
854: "No matching host key fingerprint"
855: " found in DNS.\n");
856: }
1.119 markus 857: snprintf(msg, sizeof(msg),
1.108 markus 858: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 859: "established%s\n"
1.209 grunk 860: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 861: "Are you sure you want to continue connecting "
1.312 dtucker 862: "(yes/no/[fingerprint])? ",
1.209 grunk 863: host, ip, msg1, type, fp,
864: options.visual_host_key ? "\n" : "",
865: options.visual_host_key ? ra : "",
866: msg2);
1.238 djm 867: free(ra);
1.312 dtucker 868: confirmed = confirm(msg, fp);
1.238 djm 869: free(fp);
1.312 dtucker 870: if (!confirmed)
1.108 markus 871: goto fail;
1.257 djm 872: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 873: }
1.161 djm 874: /*
1.285 djm 875: * If in "new" or "off" strict mode, add the key automatically
876: * to the local known_hosts file.
1.161 djm 877: */
1.88 markus 878: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 879: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 880: hostp = hostline;
1.161 djm 881: if (options.hash_known_hosts) {
882: /* Add hash of host and IP separately */
1.234 djm 883: r = add_host_to_hostfile(user_hostfiles[0],
884: host, host_key, options.hash_known_hosts) &&
885: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 886: host_key, options.hash_known_hosts);
887: } else {
888: /* Add unhashed "host,ip" */
1.234 djm 889: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 890: hostline, host_key,
891: options.hash_known_hosts);
892: }
893: } else {
1.234 djm 894: r = add_host_to_hostfile(user_hostfiles[0], host,
895: host_key, options.hash_known_hosts);
1.38 markus 896: hostp = host;
1.161 djm 897: }
1.38 markus 898:
1.161 djm 899: if (!r)
1.138 itojun 900: logit("Failed to add the host to the list of known "
1.234 djm 901: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 902: else
1.138 itojun 903: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 904: "list of known hosts.", hostp, type);
1.38 markus 905: break;
1.220 djm 906: case HOST_REVOKED:
907: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
908: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
909: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
910: error("The %s host key for %s is marked as revoked.", type, host);
911: error("This could mean that a stolen key is being used to");
912: error("impersonate this host.");
913:
914: /*
915: * If strict host key checking is in use, the user will have
916: * to edit the key manually and we can only abort.
917: */
1.285 djm 918: if (options.strict_host_key_checking !=
919: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 920: error("%s host key for %.200s was revoked and you have "
921: "requested strict checking.", type, host);
922: goto fail;
923: }
924: goto continue_unsafe;
925:
1.38 markus 926: case HOST_CHANGED:
1.219 djm 927: if (want_cert) {
928: /*
929: * This is only a debug() since it is valid to have
930: * CAs with wildcard DNS matches that don't match
931: * all hosts that one might visit.
932: */
933: debug("Host certificate authority does not "
1.229 djm 934: "match %s in %s:%lu", CA_MARKER,
935: host_found->file, host_found->line);
1.219 djm 936: goto fail;
937: }
1.197 dtucker 938: if (readonly == ROQUIET)
939: goto fail;
1.38 markus 940: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 941: char *key_msg;
1.38 markus 942: if (ip_status == HOST_NEW)
1.158 avsm 943: key_msg = "is unknown";
1.38 markus 944: else if (ip_status == HOST_OK)
1.158 avsm 945: key_msg = "is unchanged";
1.38 markus 946: else
1.158 avsm 947: key_msg = "has a different value";
1.38 markus 948: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
949: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
950: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 951: error("The %s host key for %s has changed,", type, host);
1.208 ian 952: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 953: error("%s. This could either mean that", key_msg);
1.38 markus 954: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 955: error("and its host key have changed at the same time.");
1.88 markus 956: if (ip_status != HOST_NEW)
1.229 djm 957: error("Offending key for IP in %s:%lu",
958: ip_found->file, ip_found->line);
1.38 markus 959: }
960: /* The host key has changed. */
1.150 jakob 961: warn_changed_key(host_key);
1.38 markus 962: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 963: user_hostfiles[0]);
1.280 markus 964: error("Offending %s key in %s:%lu",
965: sshkey_type(host_found->key),
1.229 djm 966: host_found->file, host_found->line);
1.38 markus 967:
1.40 markus 968: /*
969: * If strict host key checking is in use, the user will have
970: * to edit the key manually and we can only abort.
971: */
1.285 djm 972: if (options.strict_host_key_checking !=
973: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 974: error("%s host key for %.200s has changed and you have "
975: "requested strict checking.", type, host);
976: goto fail;
977: }
1.38 markus 978:
1.220 djm 979: continue_unsafe:
1.40 markus 980: /*
981: * If strict host key checking has not been requested, allow
1.144 djm 982: * the connection but without MITM-able authentication or
1.194 stevesk 983: * forwarding.
1.40 markus 984: */
1.38 markus 985: if (options.password_authentication) {
1.108 markus 986: error("Password authentication is disabled to avoid "
987: "man-in-the-middle attacks.");
1.38 markus 988: options.password_authentication = 0;
1.210 dtucker 989: cancelled_forwarding = 1;
1.144 djm 990: }
991: if (options.kbd_interactive_authentication) {
992: error("Keyboard-interactive authentication is disabled"
993: " to avoid man-in-the-middle attacks.");
994: options.kbd_interactive_authentication = 0;
995: options.challenge_response_authentication = 0;
1.210 dtucker 996: cancelled_forwarding = 1;
1.144 djm 997: }
998: if (options.challenge_response_authentication) {
999: error("Challenge/response authentication is disabled"
1000: " to avoid man-in-the-middle attacks.");
1001: options.challenge_response_authentication = 0;
1.210 dtucker 1002: cancelled_forwarding = 1;
1.38 markus 1003: }
1004: if (options.forward_agent) {
1.108 markus 1005: error("Agent forwarding is disabled to avoid "
1006: "man-in-the-middle attacks.");
1.38 markus 1007: options.forward_agent = 0;
1.210 dtucker 1008: cancelled_forwarding = 1;
1.83 markus 1009: }
1010: if (options.forward_x11) {
1.108 markus 1011: error("X11 forwarding is disabled to avoid "
1012: "man-in-the-middle attacks.");
1.83 markus 1013: options.forward_x11 = 0;
1.210 dtucker 1014: cancelled_forwarding = 1;
1.83 markus 1015: }
1.108 markus 1016: if (options.num_local_forwards > 0 ||
1017: options.num_remote_forwards > 0) {
1018: error("Port forwarding is disabled to avoid "
1019: "man-in-the-middle attacks.");
1020: options.num_local_forwards =
1.118 deraadt 1021: options.num_remote_forwards = 0;
1.210 dtucker 1022: cancelled_forwarding = 1;
1.194 stevesk 1023: }
1024: if (options.tun_open != SSH_TUNMODE_NO) {
1025: error("Tunnel forwarding is disabled to avoid "
1026: "man-in-the-middle attacks.");
1027: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1028: cancelled_forwarding = 1;
1.38 markus 1029: }
1.210 dtucker 1030: if (options.exit_on_forward_failure && cancelled_forwarding)
1031: fatal("Error: forwarding disabled due to host key "
1032: "check failure");
1033:
1.40 markus 1034: /*
1035: * XXX Should permit the user to change to use the new id.
1036: * This could be done by converting the host key to an
1037: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1038: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1039: * accept the authentication.
1040: */
1.38 markus 1041: break;
1.132 markus 1042: case HOST_FOUND:
1043: fatal("internal error");
1044: break;
1.88 markus 1045: }
1046:
1047: if (options.check_host_ip && host_status != HOST_CHANGED &&
1048: ip_status == HOST_CHANGED) {
1.119 markus 1049: snprintf(msg, sizeof(msg),
1050: "Warning: the %s host key for '%.200s' "
1051: "differs from the key for the IP address '%.128s'"
1.229 djm 1052: "\nOffending key for IP in %s:%lu",
1053: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1054: if (host_status == HOST_OK) {
1055: len = strlen(msg);
1056: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1057: "\nMatching host key in %s:%lu",
1058: host_found->file, host_found->line);
1.119 markus 1059: }
1.285 djm 1060: if (options.strict_host_key_checking ==
1061: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1062: strlcat(msg, "\nAre you sure you want "
1063: "to continue connecting (yes/no)? ", sizeof(msg));
1.312 dtucker 1064: if (!confirm(msg, NULL))
1.108 markus 1065: goto fail;
1.285 djm 1066: } else if (options.strict_host_key_checking !=
1067: SSH_STRICT_HOSTKEY_OFF) {
1068: logit("%s", msg);
1069: error("Exiting, you have requested strict checking.");
1070: goto fail;
1.119 markus 1071: } else {
1.143 djm 1072: logit("%s", msg);
1.88 markus 1073: }
1.257 djm 1074: }
1075:
1076: if (!hostkey_trusted && options.update_hostkeys) {
1077: debug("%s: hostkey not known or explicitly trusted: "
1078: "disabling UpdateHostkeys", __func__);
1079: options.update_hostkeys = 0;
1.38 markus 1080: }
1.82 provos 1081:
1.238 djm 1082: free(ip);
1083: free(host);
1.229 djm 1084: if (host_hostkeys != NULL)
1085: free_hostkeys(host_hostkeys);
1086: if (ip_hostkeys != NULL)
1087: free_hostkeys(ip_hostkeys);
1.108 markus 1088: return 0;
1089:
1090: fail:
1.220 djm 1091: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1092: /*
1093: * No matching certificate. Downgrade cert to raw key and
1094: * search normally.
1095: */
1096: debug("No matching CA found. Retry with plain key");
1.280 markus 1097: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1098: fatal("%s: sshkey_from_private: %s",
1099: __func__, ssh_err(r));
1100: if ((r = sshkey_drop_cert(raw_key)) != 0)
1101: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1102: host_key = raw_key;
1103: goto retry;
1104: }
1.293 dtucker 1105: sshkey_free(raw_key);
1.238 djm 1106: free(ip);
1107: free(host);
1.229 djm 1108: if (host_hostkeys != NULL)
1109: free_hostkeys(host_hostkeys);
1110: if (ip_hostkeys != NULL)
1111: free_hostkeys(ip_hostkeys);
1.108 markus 1112: return -1;
1113: }
1114:
1.140 jakob 1115: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1116: int
1.279 markus 1117: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1118: {
1.267 djm 1119: u_int i;
1.250 djm 1120: int r = -1, flags = 0;
1.267 djm 1121: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1122: struct sshkey *plain = NULL;
1.229 djm 1123:
1.252 djm 1124: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1125: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1126: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1127: r = -1;
1128: goto out;
1129: }
1130:
1.267 djm 1131: if (sshkey_is_cert(host_key)) {
1132: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1133: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1134: error("%s: fingerprint CA key: %s",
1135: __func__, ssh_err(r));
1136: r = -1;
1137: goto out;
1138: }
1139: sshkey_format_cert_validity(host_key->cert,
1140: valid, sizeof(valid));
1141: debug("Server host certificate: %s %s, serial %llu "
1142: "ID \"%s\" CA %s %s valid %s",
1143: sshkey_ssh_name(host_key), fp,
1.269 djm 1144: (unsigned long long)host_key->cert->serial,
1145: host_key->cert->key_id,
1.267 djm 1146: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1147: valid);
1148: for (i = 0; i < host_key->cert->nprincipals; i++) {
1149: debug2("Server host certificate hostname: %s",
1150: host_key->cert->principals[i]);
1151: }
1152: } else {
1.276 djm 1153: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1154: }
1.252 djm 1155:
1156: if (sshkey_equal(previous_host_key, host_key)) {
1157: debug2("%s: server host key %s %s matches cached key",
1158: __func__, sshkey_type(host_key), fp);
1159: r = 0;
1160: goto out;
1161: }
1162:
1163: /* Check in RevokedHostKeys file if specified */
1164: if (options.revoked_host_keys != NULL) {
1165: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1166: switch (r) {
1167: case 0:
1168: break; /* not revoked */
1169: case SSH_ERR_KEY_REVOKED:
1170: error("Host key %s %s revoked by file %s",
1171: sshkey_type(host_key), fp,
1172: options.revoked_host_keys);
1173: r = -1;
1174: goto out;
1175: default:
1176: error("Error checking host key %s %s in "
1177: "revoked keys file %s: %s", sshkey_type(host_key),
1178: fp, options.revoked_host_keys, ssh_err(r));
1179: r = -1;
1180: goto out;
1181: }
1.250 djm 1182: }
1183:
1.247 djm 1184: if (options.verify_host_key_dns) {
1185: /*
1186: * XXX certs are not yet supported for DNS, so downgrade
1187: * them and try the plain key.
1188: */
1.252 djm 1189: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1190: goto out;
1191: if (sshkey_is_cert(plain))
1192: sshkey_drop_cert(plain);
1.247 djm 1193: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1194: if (flags & DNS_VERIFY_FOUND) {
1195: if (options.verify_host_key_dns == 1 &&
1196: flags & DNS_VERIFY_MATCH &&
1197: flags & DNS_VERIFY_SECURE) {
1.250 djm 1198: r = 0;
1.252 djm 1199: goto out;
1.247 djm 1200: }
1201: if (flags & DNS_VERIFY_MATCH) {
1202: matching_host_key_dns = 1;
1203: } else {
1.287 djm 1204: warn_changed_key(plain);
1205: error("Update the SSHFP RR in DNS "
1206: "with the new host key to get rid "
1207: "of this message.");
1.247 djm 1208: }
1.153 jakob 1209: }
1.140 jakob 1210: }
1211: }
1.250 djm 1212: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1213: options.user_hostfiles, options.num_user_hostfiles,
1214: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1215:
1.252 djm 1216: out:
1217: sshkey_free(plain);
1218: free(fp);
1.267 djm 1219: free(cafp);
1.250 djm 1220: if (r == 0 && host_key != NULL) {
1.280 markus 1221: sshkey_free(previous_host_key);
1222: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1223: }
1224:
1225: return r;
1.51 markus 1226: }
1.70 markus 1227:
1.51 markus 1228: /*
1229: * Starts a dialog with the server, and authenticates the current user on the
1230: * server. This does not need any extra privileges. The basic connection
1231: * to the server must already have been established before this is called.
1232: * If login fails, this function prints an error and never returns.
1233: * This function does not require super-user privileges.
1234: */
1235: void
1.309 djm 1236: ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost,
1.229 djm 1237: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1238: {
1.241 djm 1239: char *host;
1.70 markus 1240: char *server_user, *local_user;
1241:
1242: local_user = xstrdup(pw->pw_name);
1243: server_user = options.user ? options.user : local_user;
1.51 markus 1244:
1245: /* Convert the user-supplied hostname into all lowercase. */
1246: host = xstrdup(orighost);
1.241 djm 1247: lowercase(host);
1.51 markus 1248:
1249: /* Exchange protocol version identification strings with the server. */
1.309 djm 1250: if (kex_exchange_identification(ssh, timeout_ms, NULL) != 0)
1251: cleanup_exit(255); /* error already logged */
1.51 markus 1252:
1253: /* Put the connection into non-blocking mode. */
1.309 djm 1254: ssh_packet_set_nonblocking(ssh);
1.51 markus 1255:
1256: /* key exchange */
1257: /* authenticate user */
1.261 dtucker 1258: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.309 djm 1259: ssh_kex2(ssh, host, hostaddr, port);
1260: ssh_userauth2(ssh, local_user, server_user, host, sensitive);
1.238 djm 1261: free(local_user);
1.315 dtucker 1262: free(host);
1.132 markus 1263: }
1264:
1265: /* print all known host keys for a given host, but skip keys of given type */
1266: static int
1.279 markus 1267: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1268: {
1.242 djm 1269: int type[] = {
1270: KEY_RSA,
1271: KEY_DSA,
1272: KEY_ECDSA,
1273: KEY_ED25519,
1.297 markus 1274: KEY_XMSS,
1.242 djm 1275: -1
1276: };
1.229 djm 1277: int i, ret = 0;
1278: char *fp, *ra;
1279: const struct hostkey_entry *found;
1.132 markus 1280:
1281: for (i = 0; type[i] != -1; i++) {
1282: if (type[i] == key->type)
1283: continue;
1.229 djm 1284: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1285: continue;
1.259 djm 1286: fp = sshkey_fingerprint(found->key,
1.254 djm 1287: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1288: ra = sshkey_fingerprint(found->key,
1.254 djm 1289: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1290: if (fp == NULL || ra == NULL)
1291: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1292: logit("WARNING: %s key found for host %s\n"
1293: "in %s:%lu\n"
1294: "%s key fingerprint %s.",
1.300 markus 1295: sshkey_type(found->key),
1.229 djm 1296: found->host, found->file, found->line,
1.300 markus 1297: sshkey_type(found->key), fp);
1.229 djm 1298: if (options.visual_host_key)
1299: logit("%s", ra);
1.238 djm 1300: free(ra);
1301: free(fp);
1.229 djm 1302: ret = 1;
1.132 markus 1303: }
1.229 djm 1304: return ret;
1.150 jakob 1305: }
1306:
1307: static void
1.279 markus 1308: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1309: {
1310: char *fp;
1311:
1.259 djm 1312: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1313: SSH_FP_DEFAULT);
1.259 djm 1314: if (fp == NULL)
1315: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1316:
1317: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1318: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1319: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1320: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1321: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1322: error("It is also possible that a host key has just been changed.");
1.150 jakob 1323: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.300 markus 1324: sshkey_type(host_key), fp);
1.150 jakob 1325: error("Please contact your system administrator.");
1326:
1.238 djm 1327: free(fp);
1.171 reyk 1328: }
1329:
1330: /*
1331: * Execute a local command
1332: */
1333: int
1334: ssh_local_cmd(const char *args)
1335: {
1336: char *shell;
1337: pid_t pid;
1338: int status;
1.231 djm 1339: void (*osighand)(int);
1.171 reyk 1340:
1341: if (!options.permit_local_command ||
1342: args == NULL || !*args)
1343: return (1);
1344:
1.226 djm 1345: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1346: shell = _PATH_BSHELL;
1347:
1.231 djm 1348: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1349: pid = fork();
1350: if (pid == 0) {
1.232 djm 1351: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1352: debug3("Executing %s -c \"%s\"", shell, args);
1353: execl(shell, shell, "-c", args, (char *)NULL);
1354: error("Couldn't execute %s -c \"%s\": %s",
1355: shell, args, strerror(errno));
1356: _exit(1);
1357: } else if (pid == -1)
1358: fatal("fork failed: %.100s", strerror(errno));
1359: while (waitpid(pid, &status, 0) == -1)
1360: if (errno != EINTR)
1361: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1362: signal(SIGCHLD, osighand);
1.171 reyk 1363:
1364: if (!WIFEXITED(status))
1365: return (1);
1366:
1367: return (WEXITSTATUS(status));
1.266 jcs 1368: }
1369:
1370: void
1.316 djm 1371: maybe_add_key_to_agent(char *authfile, struct sshkey *private,
1.294 djm 1372: char *comment, char *passphrase)
1.266 jcs 1373: {
1374: int auth_sock = -1, r;
1.321 djm 1375: const char *skprovider = NULL;
1.266 jcs 1376:
1377: if (options.add_keys_to_agent == 0)
1378: return;
1379:
1380: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1381: debug3("no authentication agent, not adding key");
1382: return;
1383: }
1384:
1385: if (options.add_keys_to_agent == 2 &&
1386: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1387: debug3("user denied adding this key");
1.273 dtucker 1388: close(auth_sock);
1.266 jcs 1389: return;
1390: }
1.322 markus 1391: if (sshkey_is_sk(private))
1.321 djm 1392: skprovider = options.sk_provider;
1.266 jcs 1393: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1.321 djm 1394: (options.add_keys_to_agent == 3), 0, skprovider)) == 0)
1.266 jcs 1395: debug("identity added to agent: %s", authfile);
1396: else
1397: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1398: close(auth_sock);
1.1 deraadt 1399: }
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