Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.315
1.315 ! dtucker 1: /* $OpenBSD: sshconnect.c,v 1.314 2019/02/27 19:37:01 markus Exp $ */
1.1 deraadt 2: /*
1.39 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
1.78 deraadt 8: *
9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 14: */
1.1 deraadt 15:
1.174 stevesk 16: #include <sys/types.h>
17: #include <sys/wait.h>
1.175 stevesk 18: #include <sys/stat.h>
1.187 stevesk 19: #include <sys/socket.h>
1.195 stevesk 20: #include <sys/time.h>
1.187 stevesk 21:
1.295 djm 22: #include <net/if.h>
1.187 stevesk 23: #include <netinet/in.h>
1.172 stevesk 24:
1.176 stevesk 25: #include <ctype.h>
1.190 stevesk 26: #include <errno.h>
1.216 dtucker 27: #include <fcntl.h>
1.191 stevesk 28: #include <netdb.h>
1.172 stevesk 29: #include <paths.h>
1.199 deraadt 30: #include <signal.h>
1.188 stevesk 31: #include <pwd.h>
1.198 stevesk 32: #include <stdio.h>
1.196 stevesk 33: #include <stdlib.h>
1.193 stevesk 34: #include <string.h>
1.192 stevesk 35: #include <unistd.h>
1.295 djm 36: #include <ifaddrs.h>
1.71 markus 37:
1.199 deraadt 38: #include "xmalloc.h"
1.91 markus 39: #include "ssh.h"
1.299 markus 40: #include "sshbuf.h"
1.1 deraadt 41: #include "packet.h"
1.21 markus 42: #include "compat.h"
1.300 markus 43: #include "sshkey.h"
1.71 markus 44: #include "sshconnect.h"
1.58 markus 45: #include "hostfile.h"
1.91 markus 46: #include "log.h"
1.251 millert 47: #include "misc.h"
1.91 markus 48: #include "readconf.h"
49: #include "atomicio.h"
1.140 jakob 50: #include "dns.h"
1.239 djm 51: #include "monitor_fdpass.h"
1.219 djm 52: #include "ssh2.h"
1.186 stevesk 53: #include "version.h"
1.252 djm 54: #include "authfile.h"
55: #include "ssherr.h"
1.266 jcs 56: #include "authfd.h"
1.309 djm 57: #include "kex.h"
1.310 djm 58:
1.279 markus 59: struct sshkey *previous_host_key = NULL;
1.59 markus 60:
1.169 stevesk 61: static int matching_host_key_dns = 0;
1.145 jakob 62:
1.227 djm 63: static pid_t proxy_command_pid = 0;
64:
1.124 markus 65: /* import */
1.307 djm 66: extern int debug_flag;
1.43 markus 67: extern Options options;
1.50 markus 68: extern char *__progname;
1.91 markus 69:
1.279 markus 70: static int show_other_keys(struct hostkeys *, struct sshkey *);
71: static void warn_changed_key(struct sshkey *);
1.132 markus 72:
1.239 djm 73: /* Expand a proxy command */
74: static char *
75: expand_proxy_command(const char *proxy_command, const char *user,
76: const char *host, int port)
77: {
78: char *tmp, *ret, strport[NI_MAXSERV];
79:
1.241 djm 80: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 81: xasprintf(&tmp, "exec %s", proxy_command);
82: ret = percent_expand(tmp, "h", host, "p", strport,
83: "r", options.user, (char *)NULL);
84: free(tmp);
85: return ret;
86: }
87:
1.307 djm 88: static void
89: stderr_null(void)
90: {
91: int devnull;
92:
93: if ((devnull = open(_PATH_DEVNULL, O_WRONLY)) == -1) {
94: error("Can't open %s for stderr redirection: %s",
95: _PATH_DEVNULL, strerror(errno));
96: return;
97: }
98: if (devnull == STDERR_FILENO)
99: return;
100: if (dup2(devnull, STDERR_FILENO) == -1)
101: error("Cannot redirect stderr to %s", _PATH_DEVNULL);
102: if (devnull > STDERR_FILENO)
103: close(devnull);
104: }
105:
1.239 djm 106: /*
107: * Connect to the given ssh server using a proxy command that passes a
108: * a connected fd back to us.
109: */
110: static int
1.286 djm 111: ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, u_short port,
1.239 djm 112: const char *proxy_command)
113: {
114: char *command_string;
115: int sp[2], sock;
116: pid_t pid;
117: char *shell;
118:
119: if ((shell = getenv("SHELL")) == NULL)
120: shell = _PATH_BSHELL;
121:
122: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
123: fatal("Could not create socketpair to communicate with "
124: "proxy dialer: %.100s", strerror(errno));
125:
126: command_string = expand_proxy_command(proxy_command, options.user,
127: host, port);
128: debug("Executing proxy dialer command: %.500s", command_string);
129:
130: /* Fork and execute the proxy command. */
131: if ((pid = fork()) == 0) {
132: char *argv[10];
133:
134: close(sp[1]);
135: /* Redirect stdin and stdout. */
136: if (sp[0] != 0) {
137: if (dup2(sp[0], 0) < 0)
138: perror("dup2 stdin");
139: }
140: if (sp[0] != 1) {
141: if (dup2(sp[0], 1) < 0)
142: perror("dup2 stdout");
143: }
144: if (sp[0] >= 2)
145: close(sp[0]);
146:
147: /*
1.307 djm 148: * Stderr is left for non-ControlPersist connections is so
149: * error messages may be printed on the user's terminal.
1.239 djm 150: */
1.308 dtucker 151: if (!debug_flag && options.control_path != NULL &&
152: options.control_persist)
1.307 djm 153: stderr_null();
154:
1.239 djm 155: argv[0] = shell;
156: argv[1] = "-c";
157: argv[2] = command_string;
158: argv[3] = NULL;
159:
160: /*
161: * Execute the proxy command.
162: * Note that we gave up any extra privileges above.
163: */
164: execv(argv[0], argv);
165: perror(argv[0]);
166: exit(1);
167: }
168: /* Parent. */
169: if (pid < 0)
170: fatal("fork failed: %.100s", strerror(errno));
171: close(sp[0]);
172: free(command_string);
173:
174: if ((sock = mm_receive_fd(sp[1])) == -1)
175: fatal("proxy dialer did not pass back a connection");
1.271 markus 176: close(sp[1]);
1.239 djm 177:
178: while (waitpid(pid, NULL, 0) == -1)
179: if (errno != EINTR)
180: fatal("Couldn't wait for child: %s", strerror(errno));
181:
182: /* Set the connection file descriptors. */
1.286 djm 183: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
184: return -1; /* ssh_packet_set_connection logs error */
1.239 djm 185:
186: return 0;
187: }
188:
1.39 deraadt 189: /*
190: * Connect to the given ssh server using a proxy command.
191: */
1.109 itojun 192: static int
1.286 djm 193: ssh_proxy_connect(struct ssh *ssh, const char *host, u_short port,
194: const char *proxy_command)
1.1 deraadt 195: {
1.239 djm 196: char *command_string;
1.38 markus 197: int pin[2], pout[2];
1.69 deraadt 198: pid_t pid;
1.239 djm 199: char *shell;
1.237 markus 200:
1.226 djm 201: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 202: shell = _PATH_BSHELL;
1.38 markus 203:
204: /* Create pipes for communicating with the proxy. */
205: if (pipe(pin) < 0 || pipe(pout) < 0)
206: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 207: strerror(errno));
1.38 markus 208:
1.239 djm 209: command_string = expand_proxy_command(proxy_command, options.user,
210: host, port);
1.38 markus 211: debug("Executing proxy command: %.500s", command_string);
212:
213: /* Fork and execute the proxy command. */
214: if ((pid = fork()) == 0) {
215: char *argv[10];
216:
217: /* Redirect stdin and stdout. */
218: close(pin[1]);
219: if (pin[0] != 0) {
220: if (dup2(pin[0], 0) < 0)
221: perror("dup2 stdin");
222: close(pin[0]);
223: }
224: close(pout[0]);
225: if (dup2(pout[1], 1) < 0)
226: perror("dup2 stdout");
227: /* Cannot be 1 because pin allocated two descriptors. */
228: close(pout[1]);
229:
1.307 djm 230: /*
231: * Stderr is left for non-ControlPersist connections is so
232: * error messages may be printed on the user's terminal.
233: */
1.308 dtucker 234: if (!debug_flag && options.control_path != NULL &&
235: options.control_persist)
1.307 djm 236: stderr_null();
237:
1.201 djm 238: argv[0] = shell;
1.38 markus 239: argv[1] = "-c";
240: argv[2] = command_string;
241: argv[3] = NULL;
242:
243: /* Execute the proxy command. Note that we gave up any
244: extra privileges above. */
1.232 djm 245: signal(SIGPIPE, SIG_DFL);
1.89 markus 246: execv(argv[0], argv);
247: perror(argv[0]);
1.38 markus 248: exit(1);
249: }
250: /* Parent. */
251: if (pid < 0)
252: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 253: else
254: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 255:
256: /* Close child side of the descriptors. */
257: close(pin[0]);
258: close(pout[1]);
259:
260: /* Free the command name. */
1.238 djm 261: free(command_string);
1.38 markus 262:
263: /* Set the connection file descriptors. */
1.286 djm 264: if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
265: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 266:
1.110 markus 267: return 0;
1.227 djm 268: }
269:
270: void
271: ssh_kill_proxy_command(void)
272: {
273: /*
274: * Send SIGHUP to proxy command if used. We don't wait() in
275: * case it hangs and instead rely on init to reap the child
276: */
277: if (proxy_command_pid > 1)
1.228 djm 278: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 279: }
280:
1.39 deraadt 281: /*
1.295 djm 282: * Search a interface address list (returned from getifaddrs(3)) for an
1.298 djm 283: * address that matches the desired address family on the specified interface.
1.295 djm 284: * Returns 0 and fills in *resultp and *rlenp on success. Returns -1 on failure.
285: */
286: static int
287: check_ifaddrs(const char *ifname, int af, const struct ifaddrs *ifaddrs,
288: struct sockaddr_storage *resultp, socklen_t *rlenp)
289: {
290: struct sockaddr_in6 *sa6;
291: struct sockaddr_in *sa;
292: struct in6_addr *v6addr;
293: const struct ifaddrs *ifa;
294: int allow_local;
295:
296: /*
297: * Prefer addresses that are not loopback or linklocal, but use them
298: * if nothing else matches.
299: */
300: for (allow_local = 0; allow_local < 2; allow_local++) {
301: for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next) {
302: if (ifa->ifa_addr == NULL || ifa->ifa_name == NULL ||
303: (ifa->ifa_flags & IFF_UP) == 0 ||
304: ifa->ifa_addr->sa_family != af ||
305: strcmp(ifa->ifa_name, options.bind_interface) != 0)
306: continue;
307: switch (ifa->ifa_addr->sa_family) {
308: case AF_INET:
309: sa = (struct sockaddr_in *)ifa->ifa_addr;
310: if (!allow_local && sa->sin_addr.s_addr ==
311: htonl(INADDR_LOOPBACK))
312: continue;
313: if (*rlenp < sizeof(struct sockaddr_in)) {
314: error("%s: v4 addr doesn't fit",
315: __func__);
316: return -1;
317: }
318: *rlenp = sizeof(struct sockaddr_in);
319: memcpy(resultp, sa, *rlenp);
320: return 0;
321: case AF_INET6:
322: sa6 = (struct sockaddr_in6 *)ifa->ifa_addr;
323: v6addr = &sa6->sin6_addr;
324: if (!allow_local &&
325: (IN6_IS_ADDR_LINKLOCAL(v6addr) ||
326: IN6_IS_ADDR_LOOPBACK(v6addr)))
327: continue;
328: if (*rlenp < sizeof(struct sockaddr_in6)) {
329: error("%s: v6 addr doesn't fit",
330: __func__);
331: return -1;
332: }
333: *rlenp = sizeof(struct sockaddr_in6);
334: memcpy(resultp, sa6, *rlenp);
335: return 0;
336: }
337: }
338: }
339: return -1;
340: }
341:
342: /*
1.303 dtucker 343: * Creates a socket for use as the ssh connection.
1.39 deraadt 344: */
1.109 itojun 345: static int
1.302 dtucker 346: ssh_create_socket(struct addrinfo *ai)
1.1 deraadt 347: {
1.301 dtucker 348: int sock, r;
1.295 djm 349: struct sockaddr_storage bindaddr;
350: socklen_t bindaddrlen = 0;
1.246 djm 351: struct addrinfo hints, *res = NULL;
1.295 djm 352: struct ifaddrs *ifaddrs = NULL;
353: char ntop[NI_MAXHOST];
1.1 deraadt 354:
1.217 dtucker 355: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 356: if (sock < 0) {
1.240 djm 357: error("socket: %s", strerror(errno));
1.216 dtucker 358: return -1;
359: }
360: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 361:
362: /* Bind the socket to an alternative local IP address */
1.302 dtucker 363: if (options.bind_address == NULL && options.bind_interface == NULL)
1.105 markus 364: return sock;
365:
1.295 djm 366: if (options.bind_address != NULL) {
1.246 djm 367: memset(&hints, 0, sizeof(hints));
368: hints.ai_family = ai->ai_family;
369: hints.ai_socktype = ai->ai_socktype;
370: hints.ai_protocol = ai->ai_protocol;
371: hints.ai_flags = AI_PASSIVE;
1.295 djm 372: if ((r = getaddrinfo(options.bind_address, NULL,
373: &hints, &res)) != 0) {
1.246 djm 374: error("getaddrinfo: %s: %s", options.bind_address,
1.295 djm 375: ssh_gai_strerror(r));
376: goto fail;
377: }
1.296 dtucker 378: if (res == NULL) {
1.295 djm 379: error("getaddrinfo: no addrs");
380: goto fail;
381: }
382: memcpy(&bindaddr, res->ai_addr, res->ai_addrlen);
383: bindaddrlen = res->ai_addrlen;
384: } else if (options.bind_interface != NULL) {
385: if ((r = getifaddrs(&ifaddrs)) != 0) {
386: error("getifaddrs: %s: %s", options.bind_interface,
387: strerror(errno));
388: goto fail;
389: }
390: bindaddrlen = sizeof(bindaddr);
391: if (check_ifaddrs(options.bind_interface, ai->ai_family,
392: ifaddrs, &bindaddr, &bindaddrlen) != 0) {
393: logit("getifaddrs: %s: no suitable addresses",
394: options.bind_interface);
395: goto fail;
1.246 djm 396: }
1.105 markus 397: }
1.295 djm 398: if ((r = getnameinfo((struct sockaddr *)&bindaddr, bindaddrlen,
399: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST)) != 0) {
400: error("%s: getnameinfo failed: %s", __func__,
401: ssh_gai_strerror(r));
402: goto fail;
403: }
1.301 dtucker 404: if (bind(sock, (struct sockaddr *)&bindaddr, bindaddrlen) != 0) {
1.295 djm 405: error("bind %s: %s", ntop, strerror(errno));
406: goto fail;
1.38 markus 407: }
1.295 djm 408: debug("%s: bound to %s", __func__, ntop);
409: /* success */
410: goto out;
411: fail:
412: close(sock);
413: sock = -1;
414: out:
1.246 djm 415: if (res != NULL)
416: freeaddrinfo(res);
1.295 djm 417: if (ifaddrs != NULL)
418: freeifaddrs(ifaddrs);
1.38 markus 419: return sock;
1.1 deraadt 420: }
421:
1.282 djm 422: /*
1.49 markus 423: * Opens a TCP/IP connection to the remote server on the given host.
424: * The address of the remote host will be returned in hostaddr.
1.302 dtucker 425: * If port is 0, the default port will be used.
1.39 deraadt 426: * Connection_attempts specifies the maximum number of tries (one per
427: * second). If proxy_command is non-NULL, it specifies the command (with %h
428: * and %p substituted for host and port, respectively) to use to contact
429: * the daemon.
430: */
1.241 djm 431: static int
1.286 djm 432: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.241 djm 433: struct sockaddr_storage *hostaddr, u_short port, int family,
1.302 dtucker 434: int connection_attempts, int *timeout_ms, int want_keepalive)
1.1 deraadt 435: {
1.313 dtucker 436: int on = 1, saved_timeout_ms = *timeout_ms;
1.290 djm 437: int oerrno, sock = -1, attempt;
1.90 markus 438: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 439: struct addrinfo *ai;
1.38 markus 440:
1.302 dtucker 441: debug2("%s", __func__);
1.268 djm 442: memset(ntop, 0, sizeof(ntop));
443: memset(strport, 0, sizeof(strport));
1.38 markus 444:
1.181 markus 445: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 446: if (attempt > 0) {
447: /* Sleep a moment before retrying. */
448: sleep(1);
1.38 markus 449: debug("Trying again...");
1.200 markus 450: }
1.181 markus 451: /*
452: * Loop through addresses for this host, and try each one in
453: * sequence until the connection succeeds.
454: */
1.49 markus 455: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 456: if (ai->ai_family != AF_INET &&
1.290 djm 457: ai->ai_family != AF_INET6) {
458: errno = EAFNOSUPPORT;
1.49 markus 459: continue;
1.290 djm 460: }
1.49 markus 461: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
462: ntop, sizeof(ntop), strport, sizeof(strport),
463: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.290 djm 464: oerrno = errno;
1.265 djm 465: error("%s: getnameinfo failed", __func__);
1.290 djm 466: errno = oerrno;
1.49 markus 467: continue;
468: }
469: debug("Connecting to %.200s [%.100s] port %s.",
470: host, ntop, strport);
471:
472: /* Create a socket for connecting. */
1.302 dtucker 473: sock = ssh_create_socket(ai);
1.292 stsp 474: if (sock < 0) {
1.110 markus 475: /* Any error is already output */
1.290 djm 476: errno = 0;
1.49 markus 477: continue;
1.292 stsp 478: }
1.49 markus 479:
1.313 dtucker 480: *timeout_ms = saved_timeout_ms;
1.141 djm 481: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 482: timeout_ms) >= 0) {
1.49 markus 483: /* Successful connection. */
1.102 markus 484: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 485: break;
1.49 markus 486: } else {
1.290 djm 487: oerrno = errno;
1.131 itojun 488: debug("connect to address %s port %s: %s",
489: ntop, strport, strerror(errno));
1.38 markus 490: close(sock);
1.181 markus 491: sock = -1;
1.290 djm 492: errno = oerrno;
1.38 markus 493: }
494: }
1.181 markus 495: if (sock != -1)
1.49 markus 496: break; /* Successful connection. */
1.38 markus 497: }
1.49 markus 498:
1.38 markus 499: /* Return failure if we didn't get a successful connection. */
1.181 markus 500: if (sock == -1) {
1.159 markus 501: error("ssh: connect to host %s port %s: %s",
1.290 djm 502: host, strport, errno == 0 ? "failure" : strerror(errno));
503: return -1;
1.130 itojun 504: }
1.38 markus 505:
506: debug("Connection established.");
1.90 markus 507:
1.155 markus 508: /* Set SO_KEEPALIVE if requested. */
1.202 djm 509: if (want_keepalive &&
1.90 markus 510: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
511: sizeof(on)) < 0)
512: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 513:
514: /* Set the connection. */
1.286 djm 515: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
516: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 517:
1.286 djm 518: return 0;
1.59 markus 519: }
520:
1.241 djm 521: int
1.286 djm 522: ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs,
1.241 djm 523: struct sockaddr_storage *hostaddr, u_short port, int family,
1.302 dtucker 524: int connection_attempts, int *timeout_ms, int want_keepalive)
1.241 djm 525: {
1.314 markus 526: int in, out;
527:
1.241 djm 528: if (options.proxy_command == NULL) {
1.286 djm 529: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
1.302 dtucker 530: family, connection_attempts, timeout_ms, want_keepalive);
1.241 djm 531: } else if (strcmp(options.proxy_command, "-") == 0) {
1.314 markus 532: if ((in = dup(STDIN_FILENO)) < 0 ||
533: (out = dup(STDOUT_FILENO)) < 0) {
534: if (in >= 0)
535: close(in);
536: error("%s: dup() in/out failed", __func__);
537: return -1; /* ssh_packet_set_connection logs error */
538: }
539: if ((ssh_packet_set_connection(ssh, in, out)) == NULL)
1.286 djm 540: return -1; /* ssh_packet_set_connection logs error */
541: return 0;
1.241 djm 542: } else if (options.proxy_use_fdpass) {
1.286 djm 543: return ssh_proxy_fdpass_connect(ssh, host, port,
1.241 djm 544: options.proxy_command);
545: }
1.286 djm 546: return ssh_proxy_connect(ssh, host, port, options.proxy_command);
1.241 djm 547: }
548:
1.96 markus 549: /* defaults to 'no' */
1.109 itojun 550: static int
1.312 dtucker 551: confirm(const char *prompt, const char *fingerprint)
1.1 deraadt 552: {
1.119 markus 553: const char *msg, *again = "Please type 'yes' or 'no': ";
1.312 dtucker 554: const char *again_fp = "Please type 'yes', 'no' or the fingerprint: ";
1.119 markus 555: char *p;
556: int ret = -1;
1.96 markus 557:
558: if (options.batch_mode)
559: return 0;
1.312 dtucker 560: for (msg = prompt;;msg = fingerprint ? again_fp : again) {
1.119 markus 561: p = read_passphrase(msg, RP_ECHO);
1.289 djm 562: if (p == NULL)
563: return 0;
564: p[strcspn(p, "\n")] = '\0';
565: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 566: ret = 0;
1.312 dtucker 567: else if (strcasecmp(p, "yes") == 0 || (fingerprint != NULL &&
568: strcasecmp(p, fingerprint) == 0))
1.119 markus 569: ret = 1;
1.238 djm 570: free(p);
1.119 markus 571: if (ret != -1)
572: return ret;
1.1 deraadt 573: }
574: }
575:
1.219 djm 576: static int
1.305 djm 577: check_host_cert(const char *host, const struct sshkey *key)
1.219 djm 578: {
579: const char *reason;
1.305 djm 580: int r;
1.219 djm 581:
1.305 djm 582: if (sshkey_cert_check_authority(key, 1, 0, host, &reason) != 0) {
1.219 djm 583: error("%s", reason);
584: return 0;
585: }
1.305 djm 586: if (sshbuf_len(key->cert->critical) != 0) {
1.223 djm 587: error("Certificate for %s contains unsupported "
588: "critical options(s)", host);
1.219 djm 589: return 0;
590: }
1.305 djm 591: if ((r = sshkey_check_cert_sigtype(key,
592: options.ca_sign_algorithms)) != 0) {
593: logit("%s: certificate signature algorithm %s: %s", __func__,
594: (key->cert == NULL || key->cert->signature_type == NULL) ?
595: "(null)" : key->cert->signature_type, ssh_err(r));
596: return 0;
597: }
598:
1.219 djm 599: return 1;
600: }
601:
1.229 djm 602: static int
603: sockaddr_is_local(struct sockaddr *hostaddr)
604: {
605: switch (hostaddr->sa_family) {
606: case AF_INET:
607: return (ntohl(((struct sockaddr_in *)hostaddr)->
608: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
609: case AF_INET6:
610: return IN6_IS_ADDR_LOOPBACK(
611: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
612: default:
613: return 0;
614: }
615: }
616:
617: /*
618: * Prepare the hostname and ip address strings that are used to lookup
619: * host keys in known_hosts files. These may have a port number appended.
620: */
621: void
622: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
623: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
624: {
625: char ntop[NI_MAXHOST];
626:
627: /*
628: * We don't have the remote ip-address for connections
629: * using a proxy command
630: */
631: if (hostfile_ipaddr != NULL) {
632: if (options.proxy_command == NULL) {
633: if (getnameinfo(hostaddr, hostaddr->sa_len,
634: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 635: fatal("%s: getnameinfo failed", __func__);
1.229 djm 636: *hostfile_ipaddr = put_host_port(ntop, port);
637: } else {
638: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
639: "command>");
640: }
641: }
642:
643: /*
644: * Allow the user to record the key under a different name or
645: * differentiate a non-standard port. This is useful for ssh
646: * tunneling over forwarded connections or if you run multiple
647: * sshd's on different ports on the same machine.
648: */
649: if (hostfile_hostname != NULL) {
650: if (options.host_key_alias != NULL) {
651: *hostfile_hostname = xstrdup(options.host_key_alias);
652: debug("using hostkeyalias: %s", *hostfile_hostname);
653: } else {
654: *hostfile_hostname = put_host_port(hostname, port);
655: }
656: }
657: }
658:
1.39 deraadt 659: /*
1.108 markus 660: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 661: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 662: */
1.197 dtucker 663: #define RDRW 0
664: #define RDONLY 1
665: #define ROQUIET 2
1.109 itojun 666: static int
1.197 dtucker 667: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 668: struct sshkey *host_key, int readonly,
1.234 djm 669: char **user_hostfiles, u_int num_user_hostfiles,
670: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 671: {
1.234 djm 672: HostStatus host_status;
673: HostStatus ip_status;
1.279 markus 674: struct sshkey *raw_key = NULL;
1.189 dtucker 675: char *ip = NULL, *host = NULL;
1.204 grunk 676: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 677: char msg[1024];
1.234 djm 678: const char *type;
679: const struct hostkey_entry *host_found, *ip_found;
1.312 dtucker 680: int len, cancelled_forwarding = 0, confirmed;
1.234 djm 681: int local = sockaddr_is_local(hostaddr);
1.280 markus 682: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 683: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 684: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 685: u_int i;
1.49 markus 686:
687: /*
688: * Force accepting of the host key for loopback/localhost. The
689: * problem is that if the home directory is NFS-mounted to multiple
690: * machines, localhost will refer to a different machine in each of
691: * them, and the user will get bogus HOST_CHANGED warnings. This
692: * essentially disables host authentication for localhost; however,
693: * this is probably not a real problem.
694: */
1.111 markus 695: if (options.no_host_authentication_for_localhost == 1 && local &&
696: options.host_key_alias == NULL) {
1.88 markus 697: debug("Forcing accepting of host key for "
698: "loopback/localhost.");
1.108 markus 699: return 0;
1.49 markus 700: }
1.42 markus 701:
702: /*
1.229 djm 703: * Prepare the hostname and address strings used for hostkey lookup.
704: * In some cases, these will have a port number appended.
1.42 markus 705: */
1.229 djm 706: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 707:
708: /*
1.88 markus 709: * Turn off check_host_ip if the connection is to localhost, via proxy
710: * command or if we don't have a hostname to compare with
711: */
1.189 dtucker 712: if (options.check_host_ip && (local ||
713: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 714: options.check_host_ip = 0;
1.86 markus 715:
1.229 djm 716: host_hostkeys = init_hostkeys();
1.234 djm 717: for (i = 0; i < num_user_hostfiles; i++)
718: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
719: for (i = 0; i < num_system_hostfiles; i++)
720: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 721:
722: ip_hostkeys = NULL;
723: if (!want_cert && options.check_host_ip) {
724: ip_hostkeys = init_hostkeys();
1.234 djm 725: for (i = 0; i < num_user_hostfiles; i++)
726: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
727: for (i = 0; i < num_system_hostfiles; i++)
728: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 729: }
1.38 markus 730:
1.219 djm 731: retry:
1.229 djm 732: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 733: want_cert = sshkey_is_cert(host_key);
734: type = sshkey_type(host_key);
1.219 djm 735:
1.46 markus 736: /*
1.170 djm 737: * Check if the host key is present in the user's list of known
1.40 markus 738: * hosts or in the systemwide list.
739: */
1.229 djm 740: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
741: &host_found);
742:
1.40 markus 743: /*
744: * Also perform check for the ip address, skip the check if we are
1.219 djm 745: * localhost, looking for a certificate, or the hostname was an ip
746: * address to begin with.
1.40 markus 747: */
1.229 djm 748: if (!want_cert && ip_hostkeys != NULL) {
749: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
750: &ip_found);
1.38 markus 751: if (host_status == HOST_CHANGED &&
1.229 djm 752: (ip_status != HOST_CHANGED ||
753: (ip_found != NULL &&
1.280 markus 754: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 755: host_ip_differ = 1;
756: } else
757: ip_status = host_status;
758:
759: switch (host_status) {
760: case HOST_OK:
761: /* The host is known and the key matches. */
1.219 djm 762: debug("Host '%.200s' is known and matches the %s host %s.",
763: host, type, want_cert ? "certificate" : "key");
1.229 djm 764: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
765: host_found->file, host_found->line);
1.281 djm 766: if (want_cert &&
767: !check_host_cert(options.host_key_alias == NULL ?
768: hostname : options.host_key_alias, host_key))
1.219 djm 769: goto fail;
1.88 markus 770: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 771: if (readonly || want_cert)
1.138 itojun 772: logit("%s host key for IP address "
1.108 markus 773: "'%.128s' not in list of known hosts.",
774: type, ip);
1.234 djm 775: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 776: host_key, options.hash_known_hosts))
1.138 itojun 777: logit("Failed to add the %s host key for IP "
1.108 markus 778: "address '%.128s' to the list of known "
1.262 dtucker 779: "hosts (%.500s).", type, ip,
1.234 djm 780: user_hostfiles[0]);
1.88 markus 781: else
1.138 itojun 782: logit("Warning: Permanently added the %s host "
1.108 markus 783: "key for IP address '%.128s' to the list "
784: "of known hosts.", type, ip);
1.209 grunk 785: } else if (options.visual_host_key) {
1.259 djm 786: fp = sshkey_fingerprint(host_key,
1.254 djm 787: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 788: ra = sshkey_fingerprint(host_key,
1.254 djm 789: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 790: if (fp == NULL || ra == NULL)
791: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 792: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 793: free(ra);
794: free(fp);
1.38 markus 795: }
1.257 djm 796: hostkey_trusted = 1;
1.38 markus 797: break;
798: case HOST_NEW:
1.197 dtucker 799: if (options.host_key_alias == NULL && port != 0 &&
800: port != SSH_DEFAULT_PORT) {
801: debug("checking without port identifier");
1.212 stevesk 802: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 803: ROQUIET, user_hostfiles, num_user_hostfiles,
804: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 805: debug("found matching key w/out port");
806: break;
807: }
808: }
1.219 djm 809: if (readonly || want_cert)
1.108 markus 810: goto fail;
1.38 markus 811: /* The host is new. */
1.285 djm 812: if (options.strict_host_key_checking ==
813: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 814: /*
815: * User has requested strict host key checking. We
816: * will not add the host key automatically. The only
817: * alternative left is to abort.
818: */
819: error("No %s host key is known for %.200s and you "
820: "have requested strict checking.", type, host);
821: goto fail;
1.285 djm 822: } else if (options.strict_host_key_checking ==
823: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 824: char msg1[1024], msg2[1024];
825:
1.229 djm 826: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 827: snprintf(msg1, sizeof(msg1),
1.168 djm 828: "\nbut keys of different type are already"
829: " known for this host.");
1.145 jakob 830: else
831: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 832: /* The default */
1.259 djm 833: fp = sshkey_fingerprint(host_key,
1.254 djm 834: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 835: ra = sshkey_fingerprint(host_key,
1.254 djm 836: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 837: if (fp == NULL || ra == NULL)
838: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 839: msg2[0] = '\0';
840: if (options.verify_host_key_dns) {
1.153 jakob 841: if (matching_host_key_dns)
1.145 jakob 842: snprintf(msg2, sizeof(msg2),
843: "Matching host key fingerprint"
844: " found in DNS.\n");
845: else
846: snprintf(msg2, sizeof(msg2),
847: "No matching host key fingerprint"
848: " found in DNS.\n");
849: }
1.119 markus 850: snprintf(msg, sizeof(msg),
1.108 markus 851: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 852: "established%s\n"
1.209 grunk 853: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 854: "Are you sure you want to continue connecting "
1.312 dtucker 855: "(yes/no/[fingerprint])? ",
1.209 grunk 856: host, ip, msg1, type, fp,
857: options.visual_host_key ? "\n" : "",
858: options.visual_host_key ? ra : "",
859: msg2);
1.238 djm 860: free(ra);
1.312 dtucker 861: confirmed = confirm(msg, fp);
1.238 djm 862: free(fp);
1.312 dtucker 863: if (!confirmed)
1.108 markus 864: goto fail;
1.257 djm 865: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 866: }
1.161 djm 867: /*
1.285 djm 868: * If in "new" or "off" strict mode, add the key automatically
869: * to the local known_hosts file.
1.161 djm 870: */
1.88 markus 871: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 872: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 873: hostp = hostline;
1.161 djm 874: if (options.hash_known_hosts) {
875: /* Add hash of host and IP separately */
1.234 djm 876: r = add_host_to_hostfile(user_hostfiles[0],
877: host, host_key, options.hash_known_hosts) &&
878: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 879: host_key, options.hash_known_hosts);
880: } else {
881: /* Add unhashed "host,ip" */
1.234 djm 882: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 883: hostline, host_key,
884: options.hash_known_hosts);
885: }
886: } else {
1.234 djm 887: r = add_host_to_hostfile(user_hostfiles[0], host,
888: host_key, options.hash_known_hosts);
1.38 markus 889: hostp = host;
1.161 djm 890: }
1.38 markus 891:
1.161 djm 892: if (!r)
1.138 itojun 893: logit("Failed to add the host to the list of known "
1.234 djm 894: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 895: else
1.138 itojun 896: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 897: "list of known hosts.", hostp, type);
1.38 markus 898: break;
1.220 djm 899: case HOST_REVOKED:
900: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
901: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
902: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
903: error("The %s host key for %s is marked as revoked.", type, host);
904: error("This could mean that a stolen key is being used to");
905: error("impersonate this host.");
906:
907: /*
908: * If strict host key checking is in use, the user will have
909: * to edit the key manually and we can only abort.
910: */
1.285 djm 911: if (options.strict_host_key_checking !=
912: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 913: error("%s host key for %.200s was revoked and you have "
914: "requested strict checking.", type, host);
915: goto fail;
916: }
917: goto continue_unsafe;
918:
1.38 markus 919: case HOST_CHANGED:
1.219 djm 920: if (want_cert) {
921: /*
922: * This is only a debug() since it is valid to have
923: * CAs with wildcard DNS matches that don't match
924: * all hosts that one might visit.
925: */
926: debug("Host certificate authority does not "
1.229 djm 927: "match %s in %s:%lu", CA_MARKER,
928: host_found->file, host_found->line);
1.219 djm 929: goto fail;
930: }
1.197 dtucker 931: if (readonly == ROQUIET)
932: goto fail;
1.38 markus 933: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 934: char *key_msg;
1.38 markus 935: if (ip_status == HOST_NEW)
1.158 avsm 936: key_msg = "is unknown";
1.38 markus 937: else if (ip_status == HOST_OK)
1.158 avsm 938: key_msg = "is unchanged";
1.38 markus 939: else
1.158 avsm 940: key_msg = "has a different value";
1.38 markus 941: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
942: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
943: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 944: error("The %s host key for %s has changed,", type, host);
1.208 ian 945: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 946: error("%s. This could either mean that", key_msg);
1.38 markus 947: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 948: error("and its host key have changed at the same time.");
1.88 markus 949: if (ip_status != HOST_NEW)
1.229 djm 950: error("Offending key for IP in %s:%lu",
951: ip_found->file, ip_found->line);
1.38 markus 952: }
953: /* The host key has changed. */
1.150 jakob 954: warn_changed_key(host_key);
1.38 markus 955: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 956: user_hostfiles[0]);
1.280 markus 957: error("Offending %s key in %s:%lu",
958: sshkey_type(host_found->key),
1.229 djm 959: host_found->file, host_found->line);
1.38 markus 960:
1.40 markus 961: /*
962: * If strict host key checking is in use, the user will have
963: * to edit the key manually and we can only abort.
964: */
1.285 djm 965: if (options.strict_host_key_checking !=
966: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 967: error("%s host key for %.200s has changed and you have "
968: "requested strict checking.", type, host);
969: goto fail;
970: }
1.38 markus 971:
1.220 djm 972: continue_unsafe:
1.40 markus 973: /*
974: * If strict host key checking has not been requested, allow
1.144 djm 975: * the connection but without MITM-able authentication or
1.194 stevesk 976: * forwarding.
1.40 markus 977: */
1.38 markus 978: if (options.password_authentication) {
1.108 markus 979: error("Password authentication is disabled to avoid "
980: "man-in-the-middle attacks.");
1.38 markus 981: options.password_authentication = 0;
1.210 dtucker 982: cancelled_forwarding = 1;
1.144 djm 983: }
984: if (options.kbd_interactive_authentication) {
985: error("Keyboard-interactive authentication is disabled"
986: " to avoid man-in-the-middle attacks.");
987: options.kbd_interactive_authentication = 0;
988: options.challenge_response_authentication = 0;
1.210 dtucker 989: cancelled_forwarding = 1;
1.144 djm 990: }
991: if (options.challenge_response_authentication) {
992: error("Challenge/response authentication is disabled"
993: " to avoid man-in-the-middle attacks.");
994: options.challenge_response_authentication = 0;
1.210 dtucker 995: cancelled_forwarding = 1;
1.38 markus 996: }
997: if (options.forward_agent) {
1.108 markus 998: error("Agent forwarding is disabled to avoid "
999: "man-in-the-middle attacks.");
1.38 markus 1000: options.forward_agent = 0;
1.210 dtucker 1001: cancelled_forwarding = 1;
1.83 markus 1002: }
1003: if (options.forward_x11) {
1.108 markus 1004: error("X11 forwarding is disabled to avoid "
1005: "man-in-the-middle attacks.");
1.83 markus 1006: options.forward_x11 = 0;
1.210 dtucker 1007: cancelled_forwarding = 1;
1.83 markus 1008: }
1.108 markus 1009: if (options.num_local_forwards > 0 ||
1010: options.num_remote_forwards > 0) {
1011: error("Port forwarding is disabled to avoid "
1012: "man-in-the-middle attacks.");
1013: options.num_local_forwards =
1.118 deraadt 1014: options.num_remote_forwards = 0;
1.210 dtucker 1015: cancelled_forwarding = 1;
1.194 stevesk 1016: }
1017: if (options.tun_open != SSH_TUNMODE_NO) {
1018: error("Tunnel forwarding is disabled to avoid "
1019: "man-in-the-middle attacks.");
1020: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1021: cancelled_forwarding = 1;
1.38 markus 1022: }
1.210 dtucker 1023: if (options.exit_on_forward_failure && cancelled_forwarding)
1024: fatal("Error: forwarding disabled due to host key "
1025: "check failure");
1026:
1.40 markus 1027: /*
1028: * XXX Should permit the user to change to use the new id.
1029: * This could be done by converting the host key to an
1030: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1031: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1032: * accept the authentication.
1033: */
1.38 markus 1034: break;
1.132 markus 1035: case HOST_FOUND:
1036: fatal("internal error");
1037: break;
1.88 markus 1038: }
1039:
1040: if (options.check_host_ip && host_status != HOST_CHANGED &&
1041: ip_status == HOST_CHANGED) {
1.119 markus 1042: snprintf(msg, sizeof(msg),
1043: "Warning: the %s host key for '%.200s' "
1044: "differs from the key for the IP address '%.128s'"
1.229 djm 1045: "\nOffending key for IP in %s:%lu",
1046: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1047: if (host_status == HOST_OK) {
1048: len = strlen(msg);
1049: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1050: "\nMatching host key in %s:%lu",
1051: host_found->file, host_found->line);
1.119 markus 1052: }
1.285 djm 1053: if (options.strict_host_key_checking ==
1054: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1055: strlcat(msg, "\nAre you sure you want "
1056: "to continue connecting (yes/no)? ", sizeof(msg));
1.312 dtucker 1057: if (!confirm(msg, NULL))
1.108 markus 1058: goto fail;
1.285 djm 1059: } else if (options.strict_host_key_checking !=
1060: SSH_STRICT_HOSTKEY_OFF) {
1061: logit("%s", msg);
1062: error("Exiting, you have requested strict checking.");
1063: goto fail;
1.119 markus 1064: } else {
1.143 djm 1065: logit("%s", msg);
1.88 markus 1066: }
1.257 djm 1067: }
1068:
1069: if (!hostkey_trusted && options.update_hostkeys) {
1070: debug("%s: hostkey not known or explicitly trusted: "
1071: "disabling UpdateHostkeys", __func__);
1072: options.update_hostkeys = 0;
1.38 markus 1073: }
1.82 provos 1074:
1.238 djm 1075: free(ip);
1076: free(host);
1.229 djm 1077: if (host_hostkeys != NULL)
1078: free_hostkeys(host_hostkeys);
1079: if (ip_hostkeys != NULL)
1080: free_hostkeys(ip_hostkeys);
1.108 markus 1081: return 0;
1082:
1083: fail:
1.220 djm 1084: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1085: /*
1086: * No matching certificate. Downgrade cert to raw key and
1087: * search normally.
1088: */
1089: debug("No matching CA found. Retry with plain key");
1.280 markus 1090: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1091: fatal("%s: sshkey_from_private: %s",
1092: __func__, ssh_err(r));
1093: if ((r = sshkey_drop_cert(raw_key)) != 0)
1094: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1095: host_key = raw_key;
1096: goto retry;
1097: }
1.293 dtucker 1098: sshkey_free(raw_key);
1.238 djm 1099: free(ip);
1100: free(host);
1.229 djm 1101: if (host_hostkeys != NULL)
1102: free_hostkeys(host_hostkeys);
1103: if (ip_hostkeys != NULL)
1104: free_hostkeys(ip_hostkeys);
1.108 markus 1105: return -1;
1106: }
1107:
1.140 jakob 1108: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1109: int
1.279 markus 1110: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1111: {
1.267 djm 1112: u_int i;
1.250 djm 1113: int r = -1, flags = 0;
1.267 djm 1114: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1115: struct sshkey *plain = NULL;
1.229 djm 1116:
1.252 djm 1117: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1118: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1119: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1120: r = -1;
1121: goto out;
1122: }
1123:
1.267 djm 1124: if (sshkey_is_cert(host_key)) {
1125: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1126: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1127: error("%s: fingerprint CA key: %s",
1128: __func__, ssh_err(r));
1129: r = -1;
1130: goto out;
1131: }
1132: sshkey_format_cert_validity(host_key->cert,
1133: valid, sizeof(valid));
1134: debug("Server host certificate: %s %s, serial %llu "
1135: "ID \"%s\" CA %s %s valid %s",
1136: sshkey_ssh_name(host_key), fp,
1.269 djm 1137: (unsigned long long)host_key->cert->serial,
1138: host_key->cert->key_id,
1.267 djm 1139: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1140: valid);
1141: for (i = 0; i < host_key->cert->nprincipals; i++) {
1142: debug2("Server host certificate hostname: %s",
1143: host_key->cert->principals[i]);
1144: }
1145: } else {
1.276 djm 1146: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1147: }
1.252 djm 1148:
1149: if (sshkey_equal(previous_host_key, host_key)) {
1150: debug2("%s: server host key %s %s matches cached key",
1151: __func__, sshkey_type(host_key), fp);
1152: r = 0;
1153: goto out;
1154: }
1155:
1156: /* Check in RevokedHostKeys file if specified */
1157: if (options.revoked_host_keys != NULL) {
1158: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1159: switch (r) {
1160: case 0:
1161: break; /* not revoked */
1162: case SSH_ERR_KEY_REVOKED:
1163: error("Host key %s %s revoked by file %s",
1164: sshkey_type(host_key), fp,
1165: options.revoked_host_keys);
1166: r = -1;
1167: goto out;
1168: default:
1169: error("Error checking host key %s %s in "
1170: "revoked keys file %s: %s", sshkey_type(host_key),
1171: fp, options.revoked_host_keys, ssh_err(r));
1172: r = -1;
1173: goto out;
1174: }
1.250 djm 1175: }
1176:
1.247 djm 1177: if (options.verify_host_key_dns) {
1178: /*
1179: * XXX certs are not yet supported for DNS, so downgrade
1180: * them and try the plain key.
1181: */
1.252 djm 1182: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1183: goto out;
1184: if (sshkey_is_cert(plain))
1185: sshkey_drop_cert(plain);
1.247 djm 1186: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1187: if (flags & DNS_VERIFY_FOUND) {
1188: if (options.verify_host_key_dns == 1 &&
1189: flags & DNS_VERIFY_MATCH &&
1190: flags & DNS_VERIFY_SECURE) {
1.250 djm 1191: r = 0;
1.252 djm 1192: goto out;
1.247 djm 1193: }
1194: if (flags & DNS_VERIFY_MATCH) {
1195: matching_host_key_dns = 1;
1196: } else {
1.287 djm 1197: warn_changed_key(plain);
1198: error("Update the SSHFP RR in DNS "
1199: "with the new host key to get rid "
1200: "of this message.");
1.247 djm 1201: }
1.153 jakob 1202: }
1.140 jakob 1203: }
1204: }
1.250 djm 1205: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1206: options.user_hostfiles, options.num_user_hostfiles,
1207: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1208:
1.252 djm 1209: out:
1210: sshkey_free(plain);
1211: free(fp);
1.267 djm 1212: free(cafp);
1.250 djm 1213: if (r == 0 && host_key != NULL) {
1.280 markus 1214: sshkey_free(previous_host_key);
1215: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1216: }
1217:
1218: return r;
1.51 markus 1219: }
1.70 markus 1220:
1.51 markus 1221: /*
1222: * Starts a dialog with the server, and authenticates the current user on the
1223: * server. This does not need any extra privileges. The basic connection
1224: * to the server must already have been established before this is called.
1225: * If login fails, this function prints an error and never returns.
1226: * This function does not require super-user privileges.
1227: */
1228: void
1.309 djm 1229: ssh_login(struct ssh *ssh, Sensitive *sensitive, const char *orighost,
1.229 djm 1230: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1231: {
1.241 djm 1232: char *host;
1.70 markus 1233: char *server_user, *local_user;
1234:
1235: local_user = xstrdup(pw->pw_name);
1236: server_user = options.user ? options.user : local_user;
1.51 markus 1237:
1238: /* Convert the user-supplied hostname into all lowercase. */
1239: host = xstrdup(orighost);
1.241 djm 1240: lowercase(host);
1.51 markus 1241:
1242: /* Exchange protocol version identification strings with the server. */
1.309 djm 1243: if (kex_exchange_identification(ssh, timeout_ms, NULL) != 0)
1244: cleanup_exit(255); /* error already logged */
1.51 markus 1245:
1246: /* Put the connection into non-blocking mode. */
1.309 djm 1247: ssh_packet_set_nonblocking(ssh);
1.51 markus 1248:
1249: /* key exchange */
1250: /* authenticate user */
1.261 dtucker 1251: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.309 djm 1252: ssh_kex2(ssh, host, hostaddr, port);
1253: ssh_userauth2(ssh, local_user, server_user, host, sensitive);
1.238 djm 1254: free(local_user);
1.315 ! dtucker 1255: free(host);
1.132 markus 1256: }
1257:
1258: /* print all known host keys for a given host, but skip keys of given type */
1259: static int
1.279 markus 1260: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1261: {
1.242 djm 1262: int type[] = {
1263: KEY_RSA,
1264: KEY_DSA,
1265: KEY_ECDSA,
1266: KEY_ED25519,
1.297 markus 1267: KEY_XMSS,
1.242 djm 1268: -1
1269: };
1.229 djm 1270: int i, ret = 0;
1271: char *fp, *ra;
1272: const struct hostkey_entry *found;
1.132 markus 1273:
1274: for (i = 0; type[i] != -1; i++) {
1275: if (type[i] == key->type)
1276: continue;
1.229 djm 1277: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1278: continue;
1.259 djm 1279: fp = sshkey_fingerprint(found->key,
1.254 djm 1280: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1281: ra = sshkey_fingerprint(found->key,
1.254 djm 1282: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1283: if (fp == NULL || ra == NULL)
1284: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1285: logit("WARNING: %s key found for host %s\n"
1286: "in %s:%lu\n"
1287: "%s key fingerprint %s.",
1.300 markus 1288: sshkey_type(found->key),
1.229 djm 1289: found->host, found->file, found->line,
1.300 markus 1290: sshkey_type(found->key), fp);
1.229 djm 1291: if (options.visual_host_key)
1292: logit("%s", ra);
1.238 djm 1293: free(ra);
1294: free(fp);
1.229 djm 1295: ret = 1;
1.132 markus 1296: }
1.229 djm 1297: return ret;
1.150 jakob 1298: }
1299:
1300: static void
1.279 markus 1301: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1302: {
1303: char *fp;
1304:
1.259 djm 1305: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1306: SSH_FP_DEFAULT);
1.259 djm 1307: if (fp == NULL)
1308: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1309:
1310: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1311: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1312: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1313: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1314: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1315: error("It is also possible that a host key has just been changed.");
1.150 jakob 1316: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.300 markus 1317: sshkey_type(host_key), fp);
1.150 jakob 1318: error("Please contact your system administrator.");
1319:
1.238 djm 1320: free(fp);
1.171 reyk 1321: }
1322:
1323: /*
1324: * Execute a local command
1325: */
1326: int
1327: ssh_local_cmd(const char *args)
1328: {
1329: char *shell;
1330: pid_t pid;
1331: int status;
1.231 djm 1332: void (*osighand)(int);
1.171 reyk 1333:
1334: if (!options.permit_local_command ||
1335: args == NULL || !*args)
1336: return (1);
1337:
1.226 djm 1338: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1339: shell = _PATH_BSHELL;
1340:
1.231 djm 1341: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1342: pid = fork();
1343: if (pid == 0) {
1.232 djm 1344: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1345: debug3("Executing %s -c \"%s\"", shell, args);
1346: execl(shell, shell, "-c", args, (char *)NULL);
1347: error("Couldn't execute %s -c \"%s\": %s",
1348: shell, args, strerror(errno));
1349: _exit(1);
1350: } else if (pid == -1)
1351: fatal("fork failed: %.100s", strerror(errno));
1352: while (waitpid(pid, &status, 0) == -1)
1353: if (errno != EINTR)
1354: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1355: signal(SIGCHLD, osighand);
1.171 reyk 1356:
1357: if (!WIFEXITED(status))
1358: return (1);
1359:
1360: return (WEXITSTATUS(status));
1.266 jcs 1361: }
1362:
1363: void
1.294 djm 1364: maybe_add_key_to_agent(char *authfile, const struct sshkey *private,
1365: char *comment, char *passphrase)
1.266 jcs 1366: {
1367: int auth_sock = -1, r;
1368:
1369: if (options.add_keys_to_agent == 0)
1370: return;
1371:
1372: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1373: debug3("no authentication agent, not adding key");
1374: return;
1375: }
1376:
1377: if (options.add_keys_to_agent == 2 &&
1378: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1379: debug3("user denied adding this key");
1.273 dtucker 1380: close(auth_sock);
1.266 jcs 1381: return;
1382: }
1383:
1384: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1.297 markus 1385: (options.add_keys_to_agent == 3), 0)) == 0)
1.266 jcs 1386: debug("identity added to agent: %s", authfile);
1387: else
1388: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1389: close(auth_sock);
1.1 deraadt 1390: }
![[BACK]](/icons/back.gif){kind=icon}
Return to sshconnect.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh