Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.325
1.325 ! naddy 1: /* $OpenBSD: sshconnect.c,v 1.324 2020/01/09 03:28:38 djm Exp $ */
1.1 deraadt 2: /*
1.39 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
1.78 deraadt 8: *
9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 14: */
1.1 deraadt 15:
1.174 stevesk 16: #include <sys/types.h>
17: #include <sys/wait.h>
1.175 stevesk 18: #include <sys/stat.h>
1.187 stevesk 19: #include <sys/socket.h>
1.195 stevesk 20: #include <sys/time.h>
1.187 stevesk 21:
1.295 djm 22: #include <net/if.h>
1.187 stevesk 23: #include <netinet/in.h>
1.172 stevesk 24:
1.176 stevesk 25: #include <ctype.h>
1.190 stevesk 26: #include <errno.h>
1.216 dtucker 27: #include <fcntl.h>
1.191 stevesk 28: #include <netdb.h>
1.172 stevesk 29: #include <paths.h>
1.199 deraadt 30: #include <signal.h>
1.188 stevesk 31: #include <pwd.h>
1.198 stevesk 32: #include <stdio.h>
1.196 stevesk 33: #include <stdlib.h>
1.323 deraadt 34: #include <stdarg.h>
1.193 stevesk 35: #include <string.h>
1.192 stevesk 36: #include <unistd.h>
1.295 djm 37: #include <ifaddrs.h>
1.71 markus 38:
1.199 deraadt 39: #include "xmalloc.h"
1.91 markus 40: #include "ssh.h"
1.299 markus 41: #include "sshbuf.h"
1.1 deraadt 42: #include "packet.h"
1.21 markus 43: #include "compat.h"
1.300 markus 44: #include "sshkey.h"
1.71 markus 45: #include "sshconnect.h"
1.58 markus 46: #include "hostfile.h"
1.91 markus 47: #include "log.h"
1.251 millert 48: #include "misc.h"
1.91 markus 49: #include "readconf.h"
50: #include "atomicio.h"
1.140 jakob 51: #include "dns.h"
1.239 djm 52: #include "monitor_fdpass.h"
1.219 djm 53: #include "ssh2.h"
1.186 stevesk 54: #include "version.h"
1.252 djm 55: #include "authfile.h"
56: #include "ssherr.h"
1.266 jcs 57: #include "authfd.h"
1.309 djm 58: #include "kex.h"
1.310 djm 59:
1.279 markus 60: struct sshkey *previous_host_key = NULL;
1.59 markus 61:
1.169 stevesk 62: static int matching_host_key_dns = 0;
1.145 jakob 63:
1.227 djm 64: static pid_t proxy_command_pid = 0;
65:
1.124 markus 66: /* import */
1.307 djm 67: extern int debug_flag;
1.43 markus 68: extern Options options;
1.50 markus 69: extern char *__progname;
1.91 markus 70:
1.279 markus 71: static int show_other_keys(struct hostkeys *, struct sshkey *);
72: static void warn_changed_key(struct sshkey *);
1.132 markus 73:
1.239 djm 74: /* Expand a proxy command */
75: static char *
76: expand_proxy_command(const char *proxy_command, const char *user,
1.325 ! naddy 77: const char *host, const char *host_arg, int port)
1.239 djm 78: {
79: char *tmp, *ret, strport[NI_MAXSERV];
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: ";
1.119 markus 561: char *p;
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) {
1.119 markus 567: p = read_passphrase(msg, RP_ECHO);
1.289 djm 568: if (p == NULL)
569: return 0;
570: p[strcspn(p, "\n")] = '\0';
571: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 572: ret = 0;
1.312 dtucker 573: else if (strcasecmp(p, "yes") == 0 || (fingerprint != NULL &&
574: strcasecmp(p, fingerprint) == 0))
1.119 markus 575: ret = 1;
1.238 djm 576: free(p);
1.119 markus 577: if (ret != -1)
578: return ret;
1.1 deraadt 579: }
580: }
581:
1.219 djm 582: static int
1.305 djm 583: check_host_cert(const char *host, const struct sshkey *key)
1.219 djm 584: {
585: const char *reason;
1.305 djm 586: int r;
1.219 djm 587:
1.305 djm 588: if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) {
1.219 djm 589: error("%s", reason);
590: return 0;
591: }
1.305 djm 592: if (sshbuf_len(key->cert->critical) != 0) {
1.223 djm 593: error("Certificate for %s contains unsupported "
594: "critical options(s)", host);
1.219 djm 595: return 0;
596: }
1.305 djm 597: if ((r = sshkey_check_cert_sigtype(key,
598: options.ca_sign_algorithms)) != 0) {
599: logit("%s: certificate signature algorithm %s: %s", __func__,
600: (key->cert == NULL || key->cert->signature_type == NULL) ?
601: "(null)" : key->cert->signature_type, ssh_err(r));
602: return 0;
603: }
604:
1.219 djm 605: return 1;
606: }
607:
1.229 djm 608: static int
609: sockaddr_is_local(struct sockaddr *hostaddr)
610: {
611: switch (hostaddr->sa_family) {
612: case AF_INET:
613: return (ntohl(((struct sockaddr_in *)hostaddr)->
614: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
615: case AF_INET6:
616: return IN6_IS_ADDR_LOOPBACK(
617: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
618: default:
619: return 0;
620: }
621: }
622:
623: /*
624: * Prepare the hostname and ip address strings that are used to lookup
625: * host keys in known_hosts files. These may have a port number appended.
626: */
627: void
628: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
629: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
630: {
631: char ntop[NI_MAXHOST];
632:
633: /*
634: * We don't have the remote ip-address for connections
635: * using a proxy command
636: */
637: if (hostfile_ipaddr != NULL) {
638: if (options.proxy_command == NULL) {
639: if (getnameinfo(hostaddr, hostaddr->sa_len,
640: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 641: fatal("%s: getnameinfo failed", __func__);
1.229 djm 642: *hostfile_ipaddr = put_host_port(ntop, port);
643: } else {
644: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
645: "command>");
646: }
647: }
648:
649: /*
650: * Allow the user to record the key under a different name or
651: * differentiate a non-standard port. This is useful for ssh
652: * tunneling over forwarded connections or if you run multiple
653: * sshd's on different ports on the same machine.
654: */
655: if (hostfile_hostname != NULL) {
656: if (options.host_key_alias != NULL) {
657: *hostfile_hostname = xstrdup(options.host_key_alias);
658: debug("using hostkeyalias: %s", *hostfile_hostname);
659: } else {
660: *hostfile_hostname = put_host_port(hostname, port);
661: }
662: }
663: }
664:
1.39 deraadt 665: /*
1.108 markus 666: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 667: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 668: */
1.197 dtucker 669: #define RDRW 0
670: #define RDONLY 1
671: #define ROQUIET 2
1.109 itojun 672: static int
1.197 dtucker 673: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 674: struct sshkey *host_key, int readonly,
1.234 djm 675: char **user_hostfiles, u_int num_user_hostfiles,
676: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 677: {
1.234 djm 678: HostStatus host_status;
679: HostStatus ip_status;
1.279 markus 680: struct sshkey *raw_key = NULL;
1.189 dtucker 681: char *ip = NULL, *host = NULL;
1.204 grunk 682: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 683: char msg[1024];
1.234 djm 684: const char *type;
685: const struct hostkey_entry *host_found, *ip_found;
1.312 dtucker 686: int len, cancelled_forwarding = 0, confirmed;
1.234 djm 687: int local = sockaddr_is_local(hostaddr);
1.280 markus 688: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 689: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 690: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 691: u_int i;
1.49 markus 692:
693: /*
694: * Force accepting of the host key for loopback/localhost. The
695: * problem is that if the home directory is NFS-mounted to multiple
696: * machines, localhost will refer to a different machine in each of
697: * them, and the user will get bogus HOST_CHANGED warnings. This
698: * essentially disables host authentication for localhost; however,
699: * this is probably not a real problem.
700: */
1.111 markus 701: if (options.no_host_authentication_for_localhost == 1 && local &&
702: options.host_key_alias == NULL) {
1.88 markus 703: debug("Forcing accepting of host key for "
704: "loopback/localhost.");
1.108 markus 705: return 0;
1.49 markus 706: }
1.42 markus 707:
708: /*
1.229 djm 709: * Prepare the hostname and address strings used for hostkey lookup.
710: * In some cases, these will have a port number appended.
1.42 markus 711: */
1.229 djm 712: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 713:
714: /*
1.88 markus 715: * Turn off check_host_ip if the connection is to localhost, via proxy
716: * command or if we don't have a hostname to compare with
717: */
1.189 dtucker 718: if (options.check_host_ip && (local ||
719: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 720: options.check_host_ip = 0;
1.86 markus 721:
1.229 djm 722: host_hostkeys = init_hostkeys();
1.234 djm 723: for (i = 0; i < num_user_hostfiles; i++)
724: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
725: for (i = 0; i < num_system_hostfiles; i++)
726: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 727:
728: ip_hostkeys = NULL;
729: if (!want_cert && options.check_host_ip) {
730: ip_hostkeys = init_hostkeys();
1.234 djm 731: for (i = 0; i < num_user_hostfiles; i++)
732: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
733: for (i = 0; i < num_system_hostfiles; i++)
734: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 735: }
1.38 markus 736:
1.219 djm 737: retry:
1.229 djm 738: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 739: want_cert = sshkey_is_cert(host_key);
740: type = sshkey_type(host_key);
1.219 djm 741:
1.46 markus 742: /*
1.170 djm 743: * Check if the host key is present in the user's list of known
1.40 markus 744: * hosts or in the systemwide list.
745: */
1.229 djm 746: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
747: &host_found);
748:
1.40 markus 749: /*
750: * Also perform check for the ip address, skip the check if we are
1.219 djm 751: * localhost, looking for a certificate, or the hostname was an ip
752: * address to begin with.
1.40 markus 753: */
1.229 djm 754: if (!want_cert && ip_hostkeys != NULL) {
755: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
756: &ip_found);
1.38 markus 757: if (host_status == HOST_CHANGED &&
1.319 djm 758: (ip_status != HOST_CHANGED ||
1.229 djm 759: (ip_found != NULL &&
1.280 markus 760: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 761: host_ip_differ = 1;
762: } else
763: ip_status = host_status;
764:
765: switch (host_status) {
766: case HOST_OK:
767: /* The host is known and the key matches. */
1.219 djm 768: debug("Host '%.200s' is known and matches the %s host %s.",
769: host, type, want_cert ? "certificate" : "key");
1.229 djm 770: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
771: host_found->file, host_found->line);
1.281 djm 772: if (want_cert &&
773: !check_host_cert(options.host_key_alias == NULL ?
774: hostname : options.host_key_alias, host_key))
1.219 djm 775: goto fail;
1.88 markus 776: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 777: if (readonly || want_cert)
1.138 itojun 778: logit("%s host key for IP address "
1.108 markus 779: "'%.128s' not in list of known hosts.",
780: type, ip);
1.234 djm 781: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 782: host_key, options.hash_known_hosts))
1.138 itojun 783: logit("Failed to add the %s host key for IP "
1.108 markus 784: "address '%.128s' to the list of known "
1.262 dtucker 785: "hosts (%.500s).", type, ip,
1.234 djm 786: user_hostfiles[0]);
1.88 markus 787: else
1.138 itojun 788: logit("Warning: Permanently added the %s host "
1.108 markus 789: "key for IP address '%.128s' to the list "
790: "of known hosts.", type, ip);
1.209 grunk 791: } else if (options.visual_host_key) {
1.259 djm 792: fp = sshkey_fingerprint(host_key,
1.254 djm 793: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 794: ra = sshkey_fingerprint(host_key,
1.254 djm 795: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 796: if (fp == NULL || ra == NULL)
797: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 798: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 799: free(ra);
800: free(fp);
1.38 markus 801: }
1.257 djm 802: hostkey_trusted = 1;
1.38 markus 803: break;
804: case HOST_NEW:
1.197 dtucker 805: if (options.host_key_alias == NULL && port != 0 &&
806: port != SSH_DEFAULT_PORT) {
807: debug("checking without port identifier");
1.212 stevesk 808: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 809: ROQUIET, user_hostfiles, num_user_hostfiles,
810: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 811: debug("found matching key w/out port");
812: break;
813: }
814: }
1.219 djm 815: if (readonly || want_cert)
1.108 markus 816: goto fail;
1.38 markus 817: /* The host is new. */
1.285 djm 818: if (options.strict_host_key_checking ==
819: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 820: /*
821: * User has requested strict host key checking. We
822: * will not add the host key automatically. The only
823: * alternative left is to abort.
824: */
825: error("No %s host key is known for %.200s and you "
826: "have requested strict checking.", type, host);
827: goto fail;
1.285 djm 828: } else if (options.strict_host_key_checking ==
829: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 830: char msg1[1024], msg2[1024];
831:
1.229 djm 832: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 833: snprintf(msg1, sizeof(msg1),
1.168 djm 834: "\nbut keys of different type are already"
835: " known for this host.");
1.145 jakob 836: else
837: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 838: /* The default */
1.259 djm 839: fp = sshkey_fingerprint(host_key,
1.254 djm 840: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 841: ra = sshkey_fingerprint(host_key,
1.254 djm 842: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 843: if (fp == NULL || ra == NULL)
844: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 845: msg2[0] = '\0';
846: if (options.verify_host_key_dns) {
1.153 jakob 847: if (matching_host_key_dns)
1.145 jakob 848: snprintf(msg2, sizeof(msg2),
849: "Matching host key fingerprint"
850: " found in DNS.\n");
851: else
852: snprintf(msg2, sizeof(msg2),
853: "No matching host key fingerprint"
854: " found in DNS.\n");
855: }
1.119 markus 856: snprintf(msg, sizeof(msg),
1.108 markus 857: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 858: "established%s\n"
1.209 grunk 859: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 860: "Are you sure you want to continue connecting "
1.312 dtucker 861: "(yes/no/[fingerprint])? ",
1.209 grunk 862: host, ip, msg1, type, fp,
863: options.visual_host_key ? "\n" : "",
864: options.visual_host_key ? ra : "",
865: msg2);
1.238 djm 866: free(ra);
1.312 dtucker 867: confirmed = confirm(msg, fp);
1.238 djm 868: free(fp);
1.312 dtucker 869: if (!confirmed)
1.108 markus 870: goto fail;
1.257 djm 871: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 872: }
1.161 djm 873: /*
1.285 djm 874: * If in "new" or "off" strict mode, add the key automatically
875: * to the local known_hosts file.
1.161 djm 876: */
1.88 markus 877: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 878: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 879: hostp = hostline;
1.161 djm 880: if (options.hash_known_hosts) {
881: /* Add hash of host and IP separately */
1.234 djm 882: r = add_host_to_hostfile(user_hostfiles[0],
883: host, host_key, options.hash_known_hosts) &&
884: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 885: host_key, options.hash_known_hosts);
886: } else {
887: /* Add unhashed "host,ip" */
1.234 djm 888: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 889: hostline, host_key,
890: options.hash_known_hosts);
891: }
892: } else {
1.234 djm 893: r = add_host_to_hostfile(user_hostfiles[0], host,
894: host_key, options.hash_known_hosts);
1.38 markus 895: hostp = host;
1.161 djm 896: }
1.38 markus 897:
1.161 djm 898: if (!r)
1.138 itojun 899: logit("Failed to add the host to the list of known "
1.234 djm 900: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 901: else
1.138 itojun 902: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 903: "list of known hosts.", hostp, type);
1.38 markus 904: break;
1.220 djm 905: case HOST_REVOKED:
906: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
907: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
908: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
909: error("The %s host key for %s is marked as revoked.", type, host);
910: error("This could mean that a stolen key is being used to");
911: error("impersonate this host.");
912:
913: /*
914: * If strict host key checking is in use, the user will have
915: * to edit the key manually and we can only abort.
916: */
1.285 djm 917: if (options.strict_host_key_checking !=
918: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 919: error("%s host key for %.200s was revoked and you have "
920: "requested strict checking.", type, host);
921: goto fail;
922: }
923: goto continue_unsafe;
924:
1.38 markus 925: case HOST_CHANGED:
1.219 djm 926: if (want_cert) {
927: /*
928: * This is only a debug() since it is valid to have
929: * CAs with wildcard DNS matches that don't match
930: * all hosts that one might visit.
931: */
932: debug("Host certificate authority does not "
1.229 djm 933: "match %s in %s:%lu", CA_MARKER,
934: host_found->file, host_found->line);
1.219 djm 935: goto fail;
936: }
1.197 dtucker 937: if (readonly == ROQUIET)
938: goto fail;
1.38 markus 939: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 940: char *key_msg;
1.38 markus 941: if (ip_status == HOST_NEW)
1.158 avsm 942: key_msg = "is unknown";
1.38 markus 943: else if (ip_status == HOST_OK)
1.158 avsm 944: key_msg = "is unchanged";
1.38 markus 945: else
1.158 avsm 946: key_msg = "has a different value";
1.38 markus 947: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
948: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
949: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 950: error("The %s host key for %s has changed,", type, host);
1.208 ian 951: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 952: error("%s. This could either mean that", key_msg);
1.38 markus 953: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 954: error("and its host key have changed at the same time.");
1.88 markus 955: if (ip_status != HOST_NEW)
1.229 djm 956: error("Offending key for IP in %s:%lu",
957: ip_found->file, ip_found->line);
1.38 markus 958: }
959: /* The host key has changed. */
1.150 jakob 960: warn_changed_key(host_key);
1.38 markus 961: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 962: user_hostfiles[0]);
1.280 markus 963: error("Offending %s key in %s:%lu",
964: sshkey_type(host_found->key),
1.229 djm 965: host_found->file, host_found->line);
1.38 markus 966:
1.40 markus 967: /*
968: * If strict host key checking is in use, the user will have
969: * to edit the key manually and we can only abort.
970: */
1.285 djm 971: if (options.strict_host_key_checking !=
972: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 973: error("%s host key for %.200s has changed and you have "
974: "requested strict checking.", type, host);
975: goto fail;
976: }
1.38 markus 977:
1.220 djm 978: continue_unsafe:
1.40 markus 979: /*
980: * If strict host key checking has not been requested, allow
1.144 djm 981: * the connection but without MITM-able authentication or
1.194 stevesk 982: * forwarding.
1.40 markus 983: */
1.38 markus 984: if (options.password_authentication) {
1.108 markus 985: error("Password authentication is disabled to avoid "
986: "man-in-the-middle attacks.");
1.38 markus 987: options.password_authentication = 0;
1.210 dtucker 988: cancelled_forwarding = 1;
1.144 djm 989: }
990: if (options.kbd_interactive_authentication) {
991: error("Keyboard-interactive authentication is disabled"
992: " to avoid man-in-the-middle attacks.");
993: options.kbd_interactive_authentication = 0;
994: options.challenge_response_authentication = 0;
1.210 dtucker 995: cancelled_forwarding = 1;
1.144 djm 996: }
997: if (options.challenge_response_authentication) {
998: error("Challenge/response authentication is disabled"
999: " to avoid man-in-the-middle attacks.");
1000: options.challenge_response_authentication = 0;
1.210 dtucker 1001: cancelled_forwarding = 1;
1.38 markus 1002: }
1003: if (options.forward_agent) {
1.108 markus 1004: error("Agent forwarding is disabled to avoid "
1005: "man-in-the-middle attacks.");
1.38 markus 1006: options.forward_agent = 0;
1.210 dtucker 1007: cancelled_forwarding = 1;
1.83 markus 1008: }
1009: if (options.forward_x11) {
1.108 markus 1010: error("X11 forwarding is disabled to avoid "
1011: "man-in-the-middle attacks.");
1.83 markus 1012: options.forward_x11 = 0;
1.210 dtucker 1013: cancelled_forwarding = 1;
1.83 markus 1014: }
1.108 markus 1015: if (options.num_local_forwards > 0 ||
1016: options.num_remote_forwards > 0) {
1017: error("Port forwarding is disabled to avoid "
1018: "man-in-the-middle attacks.");
1019: options.num_local_forwards =
1.118 deraadt 1020: options.num_remote_forwards = 0;
1.210 dtucker 1021: cancelled_forwarding = 1;
1.194 stevesk 1022: }
1023: if (options.tun_open != SSH_TUNMODE_NO) {
1024: error("Tunnel forwarding is disabled to avoid "
1025: "man-in-the-middle attacks.");
1026: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1027: cancelled_forwarding = 1;
1.38 markus 1028: }
1.210 dtucker 1029: if (options.exit_on_forward_failure && cancelled_forwarding)
1030: fatal("Error: forwarding disabled due to host key "
1031: "check failure");
1032:
1.40 markus 1033: /*
1034: * XXX Should permit the user to change to use the new id.
1035: * This could be done by converting the host key to an
1036: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1037: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1038: * accept the authentication.
1039: */
1.38 markus 1040: break;
1.132 markus 1041: case HOST_FOUND:
1042: fatal("internal error");
1043: break;
1.88 markus 1044: }
1045:
1046: if (options.check_host_ip && host_status != HOST_CHANGED &&
1047: ip_status == HOST_CHANGED) {
1.119 markus 1048: snprintf(msg, sizeof(msg),
1049: "Warning: the %s host key for '%.200s' "
1050: "differs from the key for the IP address '%.128s'"
1.229 djm 1051: "\nOffending key for IP in %s:%lu",
1052: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1053: if (host_status == HOST_OK) {
1054: len = strlen(msg);
1055: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1056: "\nMatching host key in %s:%lu",
1057: host_found->file, host_found->line);
1.119 markus 1058: }
1.285 djm 1059: if (options.strict_host_key_checking ==
1060: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1061: strlcat(msg, "\nAre you sure you want "
1062: "to continue connecting (yes/no)? ", sizeof(msg));
1.312 dtucker 1063: if (!confirm(msg, NULL))
1.108 markus 1064: goto fail;
1.285 djm 1065: } else if (options.strict_host_key_checking !=
1066: SSH_STRICT_HOSTKEY_OFF) {
1067: logit("%s", msg);
1068: error("Exiting, you have requested strict checking.");
1069: goto fail;
1.119 markus 1070: } else {
1.143 djm 1071: logit("%s", msg);
1.88 markus 1072: }
1.257 djm 1073: }
1074:
1075: if (!hostkey_trusted && options.update_hostkeys) {
1076: debug("%s: hostkey not known or explicitly trusted: "
1077: "disabling UpdateHostkeys", __func__);
1078: options.update_hostkeys = 0;
1.38 markus 1079: }
1.82 provos 1080:
1.238 djm 1081: free(ip);
1082: free(host);
1.229 djm 1083: if (host_hostkeys != NULL)
1084: free_hostkeys(host_hostkeys);
1085: if (ip_hostkeys != NULL)
1086: free_hostkeys(ip_hostkeys);
1.108 markus 1087: return 0;
1088:
1089: fail:
1.220 djm 1090: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1091: /*
1092: * No matching certificate. Downgrade cert to raw key and
1093: * search normally.
1094: */
1095: debug("No matching CA found. Retry with plain key");
1.280 markus 1096: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1097: fatal("%s: sshkey_from_private: %s",
1098: __func__, ssh_err(r));
1099: if ((r = sshkey_drop_cert(raw_key)) != 0)
1100: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1101: host_key = raw_key;
1102: goto retry;
1103: }
1.293 dtucker 1104: sshkey_free(raw_key);
1.238 djm 1105: free(ip);
1106: free(host);
1.229 djm 1107: if (host_hostkeys != NULL)
1108: free_hostkeys(host_hostkeys);
1109: if (ip_hostkeys != NULL)
1110: free_hostkeys(ip_hostkeys);
1.108 markus 1111: return -1;
1112: }
1113:
1.140 jakob 1114: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1115: int
1.279 markus 1116: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1117: {
1.267 djm 1118: u_int i;
1.250 djm 1119: int r = -1, flags = 0;
1.267 djm 1120: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1121: struct sshkey *plain = NULL;
1.229 djm 1122:
1.252 djm 1123: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1124: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1125: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1126: r = -1;
1127: goto out;
1128: }
1129:
1.267 djm 1130: if (sshkey_is_cert(host_key)) {
1131: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1132: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1133: error("%s: fingerprint CA key: %s",
1134: __func__, ssh_err(r));
1135: r = -1;
1136: goto out;
1137: }
1138: sshkey_format_cert_validity(host_key->cert,
1139: valid, sizeof(valid));
1140: debug("Server host certificate: %s %s, serial %llu "
1141: "ID \"%s\" CA %s %s valid %s",
1142: sshkey_ssh_name(host_key), fp,
1.269 djm 1143: (unsigned long long)host_key->cert->serial,
1144: host_key->cert->key_id,
1.267 djm 1145: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1146: valid);
1147: for (i = 0; i < host_key->cert->nprincipals; i++) {
1148: debug2("Server host certificate hostname: %s",
1149: host_key->cert->principals[i]);
1150: }
1151: } else {
1.276 djm 1152: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1153: }
1.252 djm 1154:
1155: if (sshkey_equal(previous_host_key, host_key)) {
1156: debug2("%s: server host key %s %s matches cached key",
1157: __func__, sshkey_type(host_key), fp);
1158: r = 0;
1159: goto out;
1160: }
1161:
1162: /* Check in RevokedHostKeys file if specified */
1163: if (options.revoked_host_keys != NULL) {
1164: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1165: switch (r) {
1166: case 0:
1167: break; /* not revoked */
1168: case SSH_ERR_KEY_REVOKED:
1169: error("Host key %s %s revoked by file %s",
1170: sshkey_type(host_key), fp,
1171: options.revoked_host_keys);
1172: r = -1;
1173: goto out;
1174: default:
1175: error("Error checking host key %s %s in "
1176: "revoked keys file %s: %s", sshkey_type(host_key),
1177: fp, options.revoked_host_keys, ssh_err(r));
1178: r = -1;
1179: goto out;
1180: }
1.250 djm 1181: }
1182:
1.247 djm 1183: if (options.verify_host_key_dns) {
1184: /*
1185: * XXX certs are not yet supported for DNS, so downgrade
1186: * them and try the plain key.
1187: */
1.252 djm 1188: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1189: goto out;
1190: if (sshkey_is_cert(plain))
1191: sshkey_drop_cert(plain);
1.247 djm 1192: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1193: if (flags & DNS_VERIFY_FOUND) {
1194: if (options.verify_host_key_dns == 1 &&
1195: flags & DNS_VERIFY_MATCH &&
1196: flags & DNS_VERIFY_SECURE) {
1.250 djm 1197: r = 0;
1.252 djm 1198: goto out;
1.247 djm 1199: }
1200: if (flags & DNS_VERIFY_MATCH) {
1201: matching_host_key_dns = 1;
1202: } else {
1.287 djm 1203: warn_changed_key(plain);
1204: error("Update the SSHFP RR in DNS "
1205: "with the new host key to get rid "
1206: "of this message.");
1.247 djm 1207: }
1.153 jakob 1208: }
1.140 jakob 1209: }
1210: }
1.250 djm 1211: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1212: options.user_hostfiles, options.num_user_hostfiles,
1213: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1214:
1.252 djm 1215: out:
1216: sshkey_free(plain);
1217: free(fp);
1.267 djm 1218: free(cafp);
1.250 djm 1219: if (r == 0 && host_key != NULL) {
1.280 markus 1220: sshkey_free(previous_host_key);
1221: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1222: }
1223:
1224: return r;
1.51 markus 1225: }
1.70 markus 1226:
1.51 markus 1227: /*
1228: * Starts a dialog with the server, and authenticates the current user on the
1229: * server. This does not need any extra privileges. The basic connection
1230: * to the server must already have been established before this is called.
1231: * If login fails, this function prints an error and never returns.
1232: * This function does not require super-user privileges.
1233: */
1234: void
1.309 djm 1235: ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost,
1.229 djm 1236: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1237: {
1.241 djm 1238: char *host;
1.70 markus 1239: char *server_user, *local_user;
1240:
1241: local_user = xstrdup(pw->pw_name);
1242: server_user = options.user ? options.user : local_user;
1.51 markus 1243:
1244: /* Convert the user-supplied hostname into all lowercase. */
1245: host = xstrdup(orighost);
1.241 djm 1246: lowercase(host);
1.51 markus 1247:
1248: /* Exchange protocol version identification strings with the server. */
1.309 djm 1249: if (kex_exchange_identification(ssh, timeout_ms, NULL) != 0)
1250: cleanup_exit(255); /* error already logged */
1.51 markus 1251:
1252: /* Put the connection into non-blocking mode. */
1.309 djm 1253: ssh_packet_set_nonblocking(ssh);
1.51 markus 1254:
1255: /* key exchange */
1256: /* authenticate user */
1.261 dtucker 1257: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.309 djm 1258: ssh_kex2(ssh, host, hostaddr, port);
1259: ssh_userauth2(ssh, local_user, server_user, host, sensitive);
1.238 djm 1260: free(local_user);
1.315 dtucker 1261: free(host);
1.132 markus 1262: }
1263:
1264: /* print all known host keys for a given host, but skip keys of given type */
1265: static int
1.279 markus 1266: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1267: {
1.242 djm 1268: int type[] = {
1269: KEY_RSA,
1270: KEY_DSA,
1271: KEY_ECDSA,
1272: KEY_ED25519,
1.297 markus 1273: KEY_XMSS,
1.242 djm 1274: -1
1275: };
1.229 djm 1276: int i, ret = 0;
1277: char *fp, *ra;
1278: const struct hostkey_entry *found;
1.132 markus 1279:
1280: for (i = 0; type[i] != -1; i++) {
1281: if (type[i] == key->type)
1282: continue;
1.229 djm 1283: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1284: continue;
1.259 djm 1285: fp = sshkey_fingerprint(found->key,
1.254 djm 1286: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1287: ra = sshkey_fingerprint(found->key,
1.254 djm 1288: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1289: if (fp == NULL || ra == NULL)
1290: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1291: logit("WARNING: %s key found for host %s\n"
1292: "in %s:%lu\n"
1293: "%s key fingerprint %s.",
1.300 markus 1294: sshkey_type(found->key),
1.229 djm 1295: found->host, found->file, found->line,
1.300 markus 1296: sshkey_type(found->key), fp);
1.229 djm 1297: if (options.visual_host_key)
1298: logit("%s", ra);
1.238 djm 1299: free(ra);
1300: free(fp);
1.229 djm 1301: ret = 1;
1.132 markus 1302: }
1.229 djm 1303: return ret;
1.150 jakob 1304: }
1305:
1306: static void
1.279 markus 1307: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1308: {
1309: char *fp;
1310:
1.259 djm 1311: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1312: SSH_FP_DEFAULT);
1.259 djm 1313: if (fp == NULL)
1314: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1315:
1316: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1317: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1318: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1319: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1320: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1321: error("It is also possible that a host key has just been changed.");
1.150 jakob 1322: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.300 markus 1323: sshkey_type(host_key), fp);
1.150 jakob 1324: error("Please contact your system administrator.");
1325:
1.238 djm 1326: free(fp);
1.171 reyk 1327: }
1328:
1329: /*
1330: * Execute a local command
1331: */
1332: int
1333: ssh_local_cmd(const char *args)
1334: {
1335: char *shell;
1336: pid_t pid;
1337: int status;
1.231 djm 1338: void (*osighand)(int);
1.171 reyk 1339:
1340: if (!options.permit_local_command ||
1341: args == NULL || !*args)
1342: return (1);
1343:
1.226 djm 1344: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1345: shell = _PATH_BSHELL;
1346:
1.231 djm 1347: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1348: pid = fork();
1349: if (pid == 0) {
1.232 djm 1350: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1351: debug3("Executing %s -c \"%s\"", shell, args);
1352: execl(shell, shell, "-c", args, (char *)NULL);
1353: error("Couldn't execute %s -c \"%s\": %s",
1354: shell, args, strerror(errno));
1355: _exit(1);
1356: } else if (pid == -1)
1357: fatal("fork failed: %.100s", strerror(errno));
1358: while (waitpid(pid, &status, 0) == -1)
1359: if (errno != EINTR)
1360: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1361: signal(SIGCHLD, osighand);
1.171 reyk 1362:
1363: if (!WIFEXITED(status))
1364: return (1);
1365:
1366: return (WEXITSTATUS(status));
1.266 jcs 1367: }
1368:
1369: void
1.316 djm 1370: maybe_add_key_to_agent(char *authfile, struct sshkey *private,
1.294 djm 1371: char *comment, char *passphrase)
1.266 jcs 1372: {
1373: int auth_sock = -1, r;
1.321 djm 1374: const char *skprovider = NULL;
1.266 jcs 1375:
1376: if (options.add_keys_to_agent == 0)
1377: return;
1378:
1379: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1380: debug3("no authentication agent, not adding key");
1381: return;
1382: }
1383:
1384: if (options.add_keys_to_agent == 2 &&
1385: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1386: debug3("user denied adding this key");
1.273 dtucker 1387: close(auth_sock);
1.266 jcs 1388: return;
1389: }
1.322 markus 1390: if (sshkey_is_sk(private))
1.321 djm 1391: skprovider = options.sk_provider;
1.266 jcs 1392: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1.321 djm 1393: (options.add_keys_to_agent == 3), 0, skprovider)) == 0)
1.266 jcs 1394: debug("identity added to agent: %s", authfile);
1395: else
1396: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1397: close(auth_sock);
1.1 deraadt 1398: }