Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.288
1.288 ! dtucker 1: /* $OpenBSD: sshconnect.c,v 1.287 2017/09/14 04:32:21 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:
22: #include <netinet/in.h>
1.172 stevesk 23:
1.176 stevesk 24: #include <ctype.h>
1.190 stevesk 25: #include <errno.h>
1.216 dtucker 26: #include <fcntl.h>
1.191 stevesk 27: #include <netdb.h>
1.172 stevesk 28: #include <paths.h>
1.282 djm 29: #include <poll.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>
1.71 markus 36:
1.199 deraadt 37: #include "xmalloc.h"
1.91 markus 38: #include "ssh.h"
1.59 markus 39: #include "buffer.h"
1.1 deraadt 40: #include "packet.h"
41: #include "uidswap.h"
1.21 markus 42: #include "compat.h"
1.58 markus 43: #include "key.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"
1.140 jakob 57:
1.70 markus 58: char *client_version_string = NULL;
59: char *server_version_string = NULL;
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 */
1.43 markus 67: extern Options options;
1.50 markus 68: extern char *__progname;
1.124 markus 69: extern uid_t original_real_uid;
70: extern uid_t original_effective_uid;
1.91 markus 71:
1.279 markus 72: static int show_other_keys(struct hostkeys *, struct sshkey *);
73: static void warn_changed_key(struct sshkey *);
1.132 markus 74:
1.239 djm 75: /* Expand a proxy command */
76: static char *
77: expand_proxy_command(const char *proxy_command, const char *user,
78: const char *host, int port)
79: {
80: char *tmp, *ret, strport[NI_MAXSERV];
81:
1.241 djm 82: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 83: xasprintf(&tmp, "exec %s", proxy_command);
84: ret = percent_expand(tmp, "h", host, "p", strport,
85: "r", options.user, (char *)NULL);
86: free(tmp);
87: return ret;
88: }
89:
90: /*
91: * Connect to the given ssh server using a proxy command that passes a
92: * a connected fd back to us.
93: */
94: static int
1.286 djm 95: ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, u_short port,
1.239 djm 96: const char *proxy_command)
97: {
98: char *command_string;
99: int sp[2], sock;
100: pid_t pid;
101: char *shell;
102:
103: if ((shell = getenv("SHELL")) == NULL)
104: shell = _PATH_BSHELL;
105:
106: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
107: fatal("Could not create socketpair to communicate with "
108: "proxy dialer: %.100s", strerror(errno));
109:
110: command_string = expand_proxy_command(proxy_command, options.user,
111: host, port);
112: debug("Executing proxy dialer command: %.500s", command_string);
113:
114: /* Fork and execute the proxy command. */
115: if ((pid = fork()) == 0) {
116: char *argv[10];
117:
118: /* Child. Permanently give up superuser privileges. */
119: permanently_drop_suid(original_real_uid);
120:
121: close(sp[1]);
122: /* Redirect stdin and stdout. */
123: if (sp[0] != 0) {
124: if (dup2(sp[0], 0) < 0)
125: perror("dup2 stdin");
126: }
127: if (sp[0] != 1) {
128: if (dup2(sp[0], 1) < 0)
129: perror("dup2 stdout");
130: }
131: if (sp[0] >= 2)
132: close(sp[0]);
133:
134: /*
135: * Stderr is left as it is so that error messages get
136: * printed on the user's terminal.
137: */
138: argv[0] = shell;
139: argv[1] = "-c";
140: argv[2] = command_string;
141: argv[3] = NULL;
142:
143: /*
144: * Execute the proxy command.
145: * Note that we gave up any extra privileges above.
146: */
147: execv(argv[0], argv);
148: perror(argv[0]);
149: exit(1);
150: }
151: /* Parent. */
152: if (pid < 0)
153: fatal("fork failed: %.100s", strerror(errno));
154: close(sp[0]);
155: free(command_string);
156:
157: if ((sock = mm_receive_fd(sp[1])) == -1)
158: fatal("proxy dialer did not pass back a connection");
1.271 markus 159: close(sp[1]);
1.239 djm 160:
161: while (waitpid(pid, NULL, 0) == -1)
162: if (errno != EINTR)
163: fatal("Couldn't wait for child: %s", strerror(errno));
164:
165: /* Set the connection file descriptors. */
1.286 djm 166: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
167: return -1; /* ssh_packet_set_connection logs error */
1.239 djm 168:
169: return 0;
170: }
171:
1.39 deraadt 172: /*
173: * Connect to the given ssh server using a proxy command.
174: */
1.109 itojun 175: static int
1.286 djm 176: ssh_proxy_connect(struct ssh *ssh, const char *host, u_short port,
177: const char *proxy_command)
1.1 deraadt 178: {
1.239 djm 179: char *command_string;
1.38 markus 180: int pin[2], pout[2];
1.69 deraadt 181: pid_t pid;
1.239 djm 182: char *shell;
1.237 markus 183:
1.226 djm 184: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 185: shell = _PATH_BSHELL;
1.38 markus 186:
187: /* Create pipes for communicating with the proxy. */
188: if (pipe(pin) < 0 || pipe(pout) < 0)
189: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 190: strerror(errno));
1.38 markus 191:
1.239 djm 192: command_string = expand_proxy_command(proxy_command, options.user,
193: host, port);
1.38 markus 194: debug("Executing proxy command: %.500s", command_string);
195:
196: /* Fork and execute the proxy command. */
197: if ((pid = fork()) == 0) {
198: char *argv[10];
199:
200: /* Child. Permanently give up superuser privileges. */
1.184 markus 201: permanently_drop_suid(original_real_uid);
1.38 markus 202:
203: /* Redirect stdin and stdout. */
204: close(pin[1]);
205: if (pin[0] != 0) {
206: if (dup2(pin[0], 0) < 0)
207: perror("dup2 stdin");
208: close(pin[0]);
209: }
210: close(pout[0]);
211: if (dup2(pout[1], 1) < 0)
212: perror("dup2 stdout");
213: /* Cannot be 1 because pin allocated two descriptors. */
214: close(pout[1]);
215:
216: /* Stderr is left as it is so that error messages get
217: printed on the user's terminal. */
1.201 djm 218: argv[0] = shell;
1.38 markus 219: argv[1] = "-c";
220: argv[2] = command_string;
221: argv[3] = NULL;
222:
223: /* Execute the proxy command. Note that we gave up any
224: extra privileges above. */
1.232 djm 225: signal(SIGPIPE, SIG_DFL);
1.89 markus 226: execv(argv[0], argv);
227: perror(argv[0]);
1.38 markus 228: exit(1);
229: }
230: /* Parent. */
231: if (pid < 0)
232: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 233: else
234: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 235:
236: /* Close child side of the descriptors. */
237: close(pin[0]);
238: close(pout[1]);
239:
240: /* Free the command name. */
1.238 djm 241: free(command_string);
1.38 markus 242:
243: /* Set the connection file descriptors. */
1.286 djm 244: if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
245: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 246:
1.110 markus 247: return 0;
1.227 djm 248: }
249:
250: void
251: ssh_kill_proxy_command(void)
252: {
253: /*
254: * Send SIGHUP to proxy command if used. We don't wait() in
255: * case it hangs and instead rely on init to reap the child
256: */
257: if (proxy_command_pid > 1)
1.228 djm 258: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 259: }
260:
1.39 deraadt 261: /*
262: * Creates a (possibly privileged) socket for use as the ssh connection.
263: */
1.109 itojun 264: static int
1.139 markus 265: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 266: {
1.240 djm 267: int sock, r, gaierr;
1.246 djm 268: struct addrinfo hints, *res = NULL;
1.1 deraadt 269:
1.217 dtucker 270: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 271: if (sock < 0) {
1.240 djm 272: error("socket: %s", strerror(errno));
1.216 dtucker 273: return -1;
274: }
275: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 276:
277: /* Bind the socket to an alternative local IP address */
1.240 djm 278: if (options.bind_address == NULL && !privileged)
1.105 markus 279: return sock;
280:
1.246 djm 281: if (options.bind_address) {
282: memset(&hints, 0, sizeof(hints));
283: hints.ai_family = ai->ai_family;
284: hints.ai_socktype = ai->ai_socktype;
285: hints.ai_protocol = ai->ai_protocol;
286: hints.ai_flags = AI_PASSIVE;
287: gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
288: if (gaierr) {
289: error("getaddrinfo: %s: %s", options.bind_address,
290: ssh_gai_strerror(gaierr));
291: close(sock);
292: return -1;
293: }
1.105 markus 294: }
1.240 djm 295: /*
296: * If we are running as root and want to connect to a privileged
297: * port, bind our own socket to a privileged port.
298: */
299: if (privileged) {
300: PRIV_START;
1.246 djm 301: r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
1.240 djm 302: PRIV_END;
303: if (r < 0) {
304: error("bindresvport_sa: af=%d %s", ai->ai_family,
305: strerror(errno));
306: goto fail;
307: }
308: } else {
309: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
310: error("bind: %s: %s", options.bind_address,
311: strerror(errno));
312: fail:
313: close(sock);
314: freeaddrinfo(res);
315: return -1;
316: }
1.38 markus 317: }
1.246 djm 318: if (res != NULL)
319: freeaddrinfo(res);
1.38 markus 320: return sock;
1.1 deraadt 321: }
322:
1.282 djm 323: /*
324: * Wait up to *timeoutp milliseconds for fd to be readable. Updates
325: * *timeoutp with time remaining.
326: * Returns 0 if fd ready or -1 on timeout or error (see errno).
327: */
328: static int
329: waitrfd(int fd, int *timeoutp)
330: {
331: struct pollfd pfd;
332: struct timeval t_start;
333: int oerrno, r;
334:
1.288 ! dtucker 335: monotime_tv(&t_start);
1.282 djm 336: pfd.fd = fd;
337: pfd.events = POLLIN;
338: for (; *timeoutp >= 0;) {
339: r = poll(&pfd, 1, *timeoutp);
340: oerrno = errno;
341: ms_subtract_diff(&t_start, timeoutp);
342: errno = oerrno;
343: if (r > 0)
344: return 0;
345: else if (r == -1 && errno != EAGAIN)
346: return -1;
347: else if (r == 0)
348: break;
349: }
350: /* timeout */
351: errno = ETIMEDOUT;
352: return -1;
353: }
354:
1.141 djm 355: static int
356: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 357: socklen_t addrlen, int *timeoutp)
1.141 djm 358: {
1.282 djm 359: int optval = 0;
360: socklen_t optlen = sizeof(optval);
1.141 djm 361:
1.282 djm 362: /* No timeout: just do a blocking connect() */
363: if (*timeoutp <= 0)
364: return connect(sockfd, serv_addr, addrlen);
1.141 djm 365:
1.156 djm 366: set_nonblock(sockfd);
1.282 djm 367: if (connect(sockfd, serv_addr, addrlen) == 0) {
368: /* Succeeded already? */
1.156 djm 369: unset_nonblock(sockfd);
1.282 djm 370: return 0;
371: } else if (errno != EINPROGRESS)
372: return -1;
373:
374: if (waitrfd(sockfd, timeoutp) == -1)
375: return -1;
1.141 djm 376:
1.282 djm 377: /* Completed or failed */
378: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, &optlen) == -1) {
379: debug("getsockopt: %s", strerror(errno));
380: return -1;
1.141 djm 381: }
1.282 djm 382: if (optval != 0) {
383: errno = optval;
384: return -1;
1.202 djm 385: }
1.282 djm 386: unset_nonblock(sockfd);
387: return 0;
1.141 djm 388: }
389:
1.39 deraadt 390: /*
1.49 markus 391: * Opens a TCP/IP connection to the remote server on the given host.
392: * The address of the remote host will be returned in hostaddr.
1.124 markus 393: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 394: * a privileged port will be allocated to make the connection.
1.124 markus 395: * This requires super-user privileges if needpriv is true.
1.39 deraadt 396: * Connection_attempts specifies the maximum number of tries (one per
397: * second). If proxy_command is non-NULL, it specifies the command (with %h
398: * and %p substituted for host and port, respectively) to use to contact
399: * the daemon.
400: */
1.241 djm 401: static int
1.286 djm 402: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.241 djm 403: struct sockaddr_storage *hostaddr, u_short port, int family,
404: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
1.1 deraadt 405: {
1.90 markus 406: int on = 1;
1.49 markus 407: int sock = -1, attempt;
1.90 markus 408: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 409: struct addrinfo *ai;
1.38 markus 410:
1.265 djm 411: debug2("%s: needpriv %d", __func__, needpriv);
1.268 djm 412: memset(ntop, 0, sizeof(ntop));
413: memset(strport, 0, sizeof(strport));
1.38 markus 414:
1.181 markus 415: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 416: if (attempt > 0) {
417: /* Sleep a moment before retrying. */
418: sleep(1);
1.38 markus 419: debug("Trying again...");
1.200 markus 420: }
1.181 markus 421: /*
422: * Loop through addresses for this host, and try each one in
423: * sequence until the connection succeeds.
424: */
1.49 markus 425: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 426: if (ai->ai_family != AF_INET &&
427: ai->ai_family != AF_INET6)
1.49 markus 428: continue;
429: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
430: ntop, sizeof(ntop), strport, sizeof(strport),
431: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.265 djm 432: error("%s: getnameinfo failed", __func__);
1.49 markus 433: continue;
434: }
435: debug("Connecting to %.200s [%.100s] port %s.",
436: host, ntop, strport);
437:
438: /* Create a socket for connecting. */
1.139 markus 439: sock = ssh_create_socket(needpriv, ai);
1.49 markus 440: if (sock < 0)
1.110 markus 441: /* Any error is already output */
1.49 markus 442: continue;
443:
1.141 djm 444: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 445: timeout_ms) >= 0) {
1.49 markus 446: /* Successful connection. */
1.102 markus 447: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 448: break;
1.49 markus 449: } else {
1.131 itojun 450: debug("connect to address %s port %s: %s",
451: ntop, strport, strerror(errno));
1.38 markus 452: close(sock);
1.181 markus 453: sock = -1;
1.38 markus 454: }
455: }
1.181 markus 456: if (sock != -1)
1.49 markus 457: break; /* Successful connection. */
1.38 markus 458: }
1.49 markus 459:
1.38 markus 460: /* Return failure if we didn't get a successful connection. */
1.181 markus 461: if (sock == -1) {
1.159 markus 462: error("ssh: connect to host %s port %s: %s",
1.130 itojun 463: host, strport, strerror(errno));
1.159 markus 464: return (-1);
1.130 itojun 465: }
1.38 markus 466:
467: debug("Connection established.");
1.90 markus 468:
1.155 markus 469: /* Set SO_KEEPALIVE if requested. */
1.202 djm 470: if (want_keepalive &&
1.90 markus 471: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
472: sizeof(on)) < 0)
473: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 474:
475: /* Set the connection. */
1.286 djm 476: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
477: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 478:
1.286 djm 479: return 0;
1.59 markus 480: }
481:
1.241 djm 482: int
1.286 djm 483: ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs,
1.241 djm 484: struct sockaddr_storage *hostaddr, u_short port, int family,
485: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
486: {
487: if (options.proxy_command == NULL) {
1.286 djm 488: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
489: family, connection_attempts, timeout_ms, want_keepalive,
490: needpriv);
1.241 djm 491: } else if (strcmp(options.proxy_command, "-") == 0) {
1.286 djm 492: if ((ssh_packet_set_connection(ssh,
493: STDIN_FILENO, STDOUT_FILENO)) == NULL)
494: return -1; /* ssh_packet_set_connection logs error */
495: return 0;
1.241 djm 496: } else if (options.proxy_use_fdpass) {
1.286 djm 497: return ssh_proxy_fdpass_connect(ssh, host, port,
1.241 djm 498: options.proxy_command);
499: }
1.286 djm 500: return ssh_proxy_connect(ssh, host, port, options.proxy_command);
1.241 djm 501: }
502:
1.235 djm 503: static void
504: send_client_banner(int connection_out, int minor1)
505: {
506: /* Send our own protocol version identification. */
1.276 djm 507: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
508: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
1.270 markus 509: if (atomicio(vwrite, connection_out, client_version_string,
1.235 djm 510: strlen(client_version_string)) != strlen(client_version_string))
511: fatal("write: %.100s", strerror(errno));
512: chop(client_version_string);
513: debug("Local version string %.100s", client_version_string);
514: }
515:
1.43 markus 516: /*
1.39 deraadt 517: * Waits for the server identification string, and sends our own
518: * identification string.
519: */
1.213 andreas 520: void
1.202 djm 521: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 522: {
1.38 markus 523: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 524: int remote_major, remote_minor, mismatch;
1.38 markus 525: int connection_in = packet_get_connection_in();
526: int connection_out = packet_get_connection_out();
1.185 djm 527: u_int i, n;
1.202 djm 528: size_t len;
1.282 djm 529: int rc;
1.38 markus 530:
1.275 djm 531: send_client_banner(connection_out, 0);
1.235 djm 532:
1.163 avsm 533: /* Read other side's version identification. */
1.185 djm 534: for (n = 0;;) {
1.75 markus 535: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 536: if (timeout_ms > 0) {
1.282 djm 537: rc = waitrfd(connection_in, &timeout_ms);
538: if (rc == -1 && errno == ETIMEDOUT) {
1.202 djm 539: fatal("Connection timed out during "
540: "banner exchange");
1.282 djm 541: } else if (rc == -1) {
542: fatal("%s: %s",
543: __func__, strerror(errno));
1.202 djm 544: }
545: }
546:
1.270 markus 547: len = atomicio(read, connection_in, &buf[i], 1);
1.167 djm 548: if (len != 1 && errno == EPIPE)
1.202 djm 549: fatal("ssh_exchange_identification: "
550: "Connection closed by remote host");
1.163 avsm 551: else if (len != 1)
1.202 djm 552: fatal("ssh_exchange_identification: "
553: "read: %.100s", strerror(errno));
1.75 markus 554: if (buf[i] == '\r') {
555: buf[i] = '\n';
556: buf[i + 1] = 0;
557: continue; /**XXX wait for \n */
558: }
559: if (buf[i] == '\n') {
560: buf[i + 1] = 0;
561: break;
562: }
1.185 djm 563: if (++n > 65536)
1.202 djm 564: fatal("ssh_exchange_identification: "
565: "No banner received");
1.38 markus 566: }
1.75 markus 567: buf[sizeof(buf) - 1] = 0;
1.76 markus 568: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 569: break;
1.75 markus 570: debug("ssh_exchange_identification: %s", buf);
1.38 markus 571: }
1.59 markus 572: server_version_string = xstrdup(buf);
1.38 markus 573:
1.40 markus 574: /*
575: * Check that the versions match. In future this might accept
576: * several versions and set appropriate flags to handle them.
577: */
1.59 markus 578: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
579: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 580: fatal("Bad remote protocol version identification: '%.100s'", buf);
581: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 582: remote_major, remote_minor, remote_version);
1.38 markus 583:
1.255 markus 584: active_state->compat = compat_datafellows(remote_version);
1.64 markus 585: mismatch = 0;
1.59 markus 586:
1.116 deraadt 587: switch (remote_major) {
1.276 djm 588: case 2:
589: break;
1.64 markus 590: case 1:
1.276 djm 591: if (remote_minor != 99)
1.64 markus 592: mismatch = 1;
593: break;
1.68 markus 594: default:
1.64 markus 595: mismatch = 1;
596: break;
1.38 markus 597: }
1.64 markus 598: if (mismatch)
1.38 markus 599: fatal("Protocol major versions differ: %d vs. %d",
1.275 djm 600: PROTOCOL_MAJOR_2, remote_major);
1.244 djm 601: if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
602: fatal("Server version \"%.100s\" uses unsafe key agreement; "
603: "refusing connection", remote_version);
1.243 djm 604: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
605: logit("Server version \"%.100s\" uses unsafe RSA signature "
606: "scheme; disabling use of RSA keys", remote_version);
1.59 markus 607: chop(server_version_string);
1.1 deraadt 608: }
609:
1.96 markus 610: /* defaults to 'no' */
1.109 itojun 611: static int
1.112 markus 612: confirm(const char *prompt)
1.1 deraadt 613: {
1.119 markus 614: const char *msg, *again = "Please type 'yes' or 'no': ";
615: char *p;
616: int ret = -1;
1.96 markus 617:
618: if (options.batch_mode)
619: return 0;
1.119 markus 620: for (msg = prompt;;msg = again) {
621: p = read_passphrase(msg, RP_ECHO);
622: if (p == NULL ||
623: (p[0] == '\0') || (p[0] == '\n') ||
624: strncasecmp(p, "no", 2) == 0)
625: ret = 0;
1.127 markus 626: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 627: ret = 1;
1.238 djm 628: free(p);
1.119 markus 629: if (ret != -1)
630: return ret;
1.1 deraadt 631: }
632: }
633:
1.219 djm 634: static int
1.279 markus 635: check_host_cert(const char *host, const struct sshkey *host_key)
1.219 djm 636: {
637: const char *reason;
638:
639: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
640: error("%s", reason);
641: return 0;
642: }
1.249 djm 643: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 644: error("Certificate for %s contains unsupported "
645: "critical options(s)", host);
1.219 djm 646: return 0;
647: }
648: return 1;
649: }
650:
1.229 djm 651: static int
652: sockaddr_is_local(struct sockaddr *hostaddr)
653: {
654: switch (hostaddr->sa_family) {
655: case AF_INET:
656: return (ntohl(((struct sockaddr_in *)hostaddr)->
657: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
658: case AF_INET6:
659: return IN6_IS_ADDR_LOOPBACK(
660: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
661: default:
662: return 0;
663: }
664: }
665:
666: /*
667: * Prepare the hostname and ip address strings that are used to lookup
668: * host keys in known_hosts files. These may have a port number appended.
669: */
670: void
671: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
672: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
673: {
674: char ntop[NI_MAXHOST];
675:
676: /*
677: * We don't have the remote ip-address for connections
678: * using a proxy command
679: */
680: if (hostfile_ipaddr != NULL) {
681: if (options.proxy_command == NULL) {
682: if (getnameinfo(hostaddr, hostaddr->sa_len,
683: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 684: fatal("%s: getnameinfo failed", __func__);
1.229 djm 685: *hostfile_ipaddr = put_host_port(ntop, port);
686: } else {
687: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
688: "command>");
689: }
690: }
691:
692: /*
693: * Allow the user to record the key under a different name or
694: * differentiate a non-standard port. This is useful for ssh
695: * tunneling over forwarded connections or if you run multiple
696: * sshd's on different ports on the same machine.
697: */
698: if (hostfile_hostname != NULL) {
699: if (options.host_key_alias != NULL) {
700: *hostfile_hostname = xstrdup(options.host_key_alias);
701: debug("using hostkeyalias: %s", *hostfile_hostname);
702: } else {
703: *hostfile_hostname = put_host_port(hostname, port);
704: }
705: }
706: }
707:
1.39 deraadt 708: /*
1.108 markus 709: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 710: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 711: */
1.197 dtucker 712: #define RDRW 0
713: #define RDONLY 1
714: #define ROQUIET 2
1.109 itojun 715: static int
1.197 dtucker 716: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 717: struct sshkey *host_key, int readonly,
1.234 djm 718: char **user_hostfiles, u_int num_user_hostfiles,
719: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 720: {
1.234 djm 721: HostStatus host_status;
722: HostStatus ip_status;
1.279 markus 723: struct sshkey *raw_key = NULL;
1.189 dtucker 724: char *ip = NULL, *host = NULL;
1.204 grunk 725: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 726: char msg[1024];
1.234 djm 727: const char *type;
728: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 729: int len, cancelled_forwarding = 0;
1.234 djm 730: int local = sockaddr_is_local(hostaddr);
1.280 markus 731: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 732: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 733: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 734: u_int i;
1.49 markus 735:
736: /*
737: * Force accepting of the host key for loopback/localhost. The
738: * problem is that if the home directory is NFS-mounted to multiple
739: * machines, localhost will refer to a different machine in each of
740: * them, and the user will get bogus HOST_CHANGED warnings. This
741: * essentially disables host authentication for localhost; however,
742: * this is probably not a real problem.
743: */
1.111 markus 744: if (options.no_host_authentication_for_localhost == 1 && local &&
745: options.host_key_alias == NULL) {
1.88 markus 746: debug("Forcing accepting of host key for "
747: "loopback/localhost.");
1.108 markus 748: return 0;
1.49 markus 749: }
1.42 markus 750:
751: /*
1.229 djm 752: * Prepare the hostname and address strings used for hostkey lookup.
753: * In some cases, these will have a port number appended.
1.42 markus 754: */
1.229 djm 755: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 756:
757: /*
1.88 markus 758: * Turn off check_host_ip if the connection is to localhost, via proxy
759: * command or if we don't have a hostname to compare with
760: */
1.189 dtucker 761: if (options.check_host_ip && (local ||
762: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 763: options.check_host_ip = 0;
1.86 markus 764:
1.229 djm 765: host_hostkeys = init_hostkeys();
1.234 djm 766: for (i = 0; i < num_user_hostfiles; i++)
767: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
768: for (i = 0; i < num_system_hostfiles; i++)
769: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 770:
771: ip_hostkeys = NULL;
772: if (!want_cert && options.check_host_ip) {
773: ip_hostkeys = init_hostkeys();
1.234 djm 774: for (i = 0; i < num_user_hostfiles; i++)
775: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
776: for (i = 0; i < num_system_hostfiles; i++)
777: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 778: }
1.38 markus 779:
1.219 djm 780: retry:
1.229 djm 781: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 782: want_cert = sshkey_is_cert(host_key);
783: type = sshkey_type(host_key);
1.219 djm 784:
1.46 markus 785: /*
1.170 djm 786: * Check if the host key is present in the user's list of known
1.40 markus 787: * hosts or in the systemwide list.
788: */
1.229 djm 789: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
790: &host_found);
791:
1.40 markus 792: /*
793: * Also perform check for the ip address, skip the check if we are
1.219 djm 794: * localhost, looking for a certificate, or the hostname was an ip
795: * address to begin with.
1.40 markus 796: */
1.229 djm 797: if (!want_cert && ip_hostkeys != NULL) {
798: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
799: &ip_found);
1.38 markus 800: if (host_status == HOST_CHANGED &&
1.229 djm 801: (ip_status != HOST_CHANGED ||
802: (ip_found != NULL &&
1.280 markus 803: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 804: host_ip_differ = 1;
805: } else
806: ip_status = host_status;
807:
808: switch (host_status) {
809: case HOST_OK:
810: /* The host is known and the key matches. */
1.219 djm 811: debug("Host '%.200s' is known and matches the %s host %s.",
812: host, type, want_cert ? "certificate" : "key");
1.229 djm 813: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
814: host_found->file, host_found->line);
1.281 djm 815: if (want_cert &&
816: !check_host_cert(options.host_key_alias == NULL ?
817: hostname : options.host_key_alias, host_key))
1.219 djm 818: goto fail;
1.88 markus 819: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 820: if (readonly || want_cert)
1.138 itojun 821: logit("%s host key for IP address "
1.108 markus 822: "'%.128s' not in list of known hosts.",
823: type, ip);
1.234 djm 824: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 825: host_key, options.hash_known_hosts))
1.138 itojun 826: logit("Failed to add the %s host key for IP "
1.108 markus 827: "address '%.128s' to the list of known "
1.262 dtucker 828: "hosts (%.500s).", type, ip,
1.234 djm 829: user_hostfiles[0]);
1.88 markus 830: else
1.138 itojun 831: logit("Warning: Permanently added the %s host "
1.108 markus 832: "key for IP address '%.128s' to the list "
833: "of known hosts.", type, ip);
1.209 grunk 834: } else if (options.visual_host_key) {
1.259 djm 835: fp = sshkey_fingerprint(host_key,
1.254 djm 836: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 837: ra = sshkey_fingerprint(host_key,
1.254 djm 838: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 839: if (fp == NULL || ra == NULL)
840: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 841: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 842: free(ra);
843: free(fp);
1.38 markus 844: }
1.257 djm 845: hostkey_trusted = 1;
1.38 markus 846: break;
847: case HOST_NEW:
1.197 dtucker 848: if (options.host_key_alias == NULL && port != 0 &&
849: port != SSH_DEFAULT_PORT) {
850: debug("checking without port identifier");
1.212 stevesk 851: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 852: ROQUIET, user_hostfiles, num_user_hostfiles,
853: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 854: debug("found matching key w/out port");
855: break;
856: }
857: }
1.219 djm 858: if (readonly || want_cert)
1.108 markus 859: goto fail;
1.38 markus 860: /* The host is new. */
1.285 djm 861: if (options.strict_host_key_checking ==
862: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 863: /*
864: * User has requested strict host key checking. We
865: * will not add the host key automatically. The only
866: * alternative left is to abort.
867: */
868: error("No %s host key is known for %.200s and you "
869: "have requested strict checking.", type, host);
870: goto fail;
1.285 djm 871: } else if (options.strict_host_key_checking ==
872: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 873: char msg1[1024], msg2[1024];
874:
1.229 djm 875: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 876: snprintf(msg1, sizeof(msg1),
1.168 djm 877: "\nbut keys of different type are already"
878: " known for this host.");
1.145 jakob 879: else
880: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 881: /* The default */
1.259 djm 882: fp = sshkey_fingerprint(host_key,
1.254 djm 883: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 884: ra = sshkey_fingerprint(host_key,
1.254 djm 885: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 886: if (fp == NULL || ra == NULL)
887: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 888: msg2[0] = '\0';
889: if (options.verify_host_key_dns) {
1.153 jakob 890: if (matching_host_key_dns)
1.145 jakob 891: snprintf(msg2, sizeof(msg2),
892: "Matching host key fingerprint"
893: " found in DNS.\n");
894: else
895: snprintf(msg2, sizeof(msg2),
896: "No matching host key fingerprint"
897: " found in DNS.\n");
898: }
1.119 markus 899: snprintf(msg, sizeof(msg),
1.108 markus 900: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 901: "established%s\n"
1.209 grunk 902: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 903: "Are you sure you want to continue connecting "
1.132 markus 904: "(yes/no)? ",
1.209 grunk 905: host, ip, msg1, type, fp,
906: options.visual_host_key ? "\n" : "",
907: options.visual_host_key ? ra : "",
908: msg2);
1.238 djm 909: free(ra);
910: free(fp);
1.119 markus 911: if (!confirm(msg))
1.108 markus 912: goto fail;
1.257 djm 913: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 914: }
1.161 djm 915: /*
1.285 djm 916: * If in "new" or "off" strict mode, add the key automatically
917: * to the local known_hosts file.
1.161 djm 918: */
1.88 markus 919: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 920: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 921: hostp = hostline;
1.161 djm 922: if (options.hash_known_hosts) {
923: /* Add hash of host and IP separately */
1.234 djm 924: r = add_host_to_hostfile(user_hostfiles[0],
925: host, host_key, options.hash_known_hosts) &&
926: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 927: host_key, options.hash_known_hosts);
928: } else {
929: /* Add unhashed "host,ip" */
1.234 djm 930: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 931: hostline, host_key,
932: options.hash_known_hosts);
933: }
934: } else {
1.234 djm 935: r = add_host_to_hostfile(user_hostfiles[0], host,
936: host_key, options.hash_known_hosts);
1.38 markus 937: hostp = host;
1.161 djm 938: }
1.38 markus 939:
1.161 djm 940: if (!r)
1.138 itojun 941: logit("Failed to add the host to the list of known "
1.234 djm 942: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 943: else
1.138 itojun 944: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 945: "list of known hosts.", hostp, type);
1.38 markus 946: break;
1.220 djm 947: case HOST_REVOKED:
948: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
949: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
950: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
951: error("The %s host key for %s is marked as revoked.", type, host);
952: error("This could mean that a stolen key is being used to");
953: error("impersonate this host.");
954:
955: /*
956: * If strict host key checking is in use, the user will have
957: * to edit the key manually and we can only abort.
958: */
1.285 djm 959: if (options.strict_host_key_checking !=
960: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 961: error("%s host key for %.200s was revoked and you have "
962: "requested strict checking.", type, host);
963: goto fail;
964: }
965: goto continue_unsafe;
966:
1.38 markus 967: case HOST_CHANGED:
1.219 djm 968: if (want_cert) {
969: /*
970: * This is only a debug() since it is valid to have
971: * CAs with wildcard DNS matches that don't match
972: * all hosts that one might visit.
973: */
974: debug("Host certificate authority does not "
1.229 djm 975: "match %s in %s:%lu", CA_MARKER,
976: host_found->file, host_found->line);
1.219 djm 977: goto fail;
978: }
1.197 dtucker 979: if (readonly == ROQUIET)
980: goto fail;
1.38 markus 981: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 982: char *key_msg;
1.38 markus 983: if (ip_status == HOST_NEW)
1.158 avsm 984: key_msg = "is unknown";
1.38 markus 985: else if (ip_status == HOST_OK)
1.158 avsm 986: key_msg = "is unchanged";
1.38 markus 987: else
1.158 avsm 988: key_msg = "has a different value";
1.38 markus 989: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
990: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
991: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 992: error("The %s host key for %s has changed,", type, host);
1.208 ian 993: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 994: error("%s. This could either mean that", key_msg);
1.38 markus 995: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 996: error("and its host key have changed at the same time.");
1.88 markus 997: if (ip_status != HOST_NEW)
1.229 djm 998: error("Offending key for IP in %s:%lu",
999: ip_found->file, ip_found->line);
1.38 markus 1000: }
1001: /* The host key has changed. */
1.150 jakob 1002: warn_changed_key(host_key);
1.38 markus 1003: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1004: user_hostfiles[0]);
1.280 markus 1005: error("Offending %s key in %s:%lu",
1006: sshkey_type(host_found->key),
1.229 djm 1007: host_found->file, host_found->line);
1.38 markus 1008:
1.40 markus 1009: /*
1010: * If strict host key checking is in use, the user will have
1011: * to edit the key manually and we can only abort.
1012: */
1.285 djm 1013: if (options.strict_host_key_checking !=
1014: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 1015: error("%s host key for %.200s has changed and you have "
1016: "requested strict checking.", type, host);
1017: goto fail;
1018: }
1.38 markus 1019:
1.220 djm 1020: continue_unsafe:
1.40 markus 1021: /*
1022: * If strict host key checking has not been requested, allow
1.144 djm 1023: * the connection but without MITM-able authentication or
1.194 stevesk 1024: * forwarding.
1.40 markus 1025: */
1.38 markus 1026: if (options.password_authentication) {
1.108 markus 1027: error("Password authentication is disabled to avoid "
1028: "man-in-the-middle attacks.");
1.38 markus 1029: options.password_authentication = 0;
1.210 dtucker 1030: cancelled_forwarding = 1;
1.144 djm 1031: }
1032: if (options.kbd_interactive_authentication) {
1033: error("Keyboard-interactive authentication is disabled"
1034: " to avoid man-in-the-middle attacks.");
1035: options.kbd_interactive_authentication = 0;
1036: options.challenge_response_authentication = 0;
1.210 dtucker 1037: cancelled_forwarding = 1;
1.144 djm 1038: }
1039: if (options.challenge_response_authentication) {
1040: error("Challenge/response authentication is disabled"
1041: " to avoid man-in-the-middle attacks.");
1042: options.challenge_response_authentication = 0;
1.210 dtucker 1043: cancelled_forwarding = 1;
1.38 markus 1044: }
1045: if (options.forward_agent) {
1.108 markus 1046: error("Agent forwarding is disabled to avoid "
1047: "man-in-the-middle attacks.");
1.38 markus 1048: options.forward_agent = 0;
1.210 dtucker 1049: cancelled_forwarding = 1;
1.83 markus 1050: }
1051: if (options.forward_x11) {
1.108 markus 1052: error("X11 forwarding is disabled to avoid "
1053: "man-in-the-middle attacks.");
1.83 markus 1054: options.forward_x11 = 0;
1.210 dtucker 1055: cancelled_forwarding = 1;
1.83 markus 1056: }
1.108 markus 1057: if (options.num_local_forwards > 0 ||
1058: options.num_remote_forwards > 0) {
1059: error("Port forwarding is disabled to avoid "
1060: "man-in-the-middle attacks.");
1061: options.num_local_forwards =
1.118 deraadt 1062: options.num_remote_forwards = 0;
1.210 dtucker 1063: cancelled_forwarding = 1;
1.194 stevesk 1064: }
1065: if (options.tun_open != SSH_TUNMODE_NO) {
1066: error("Tunnel forwarding is disabled to avoid "
1067: "man-in-the-middle attacks.");
1068: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1069: cancelled_forwarding = 1;
1.38 markus 1070: }
1.210 dtucker 1071: if (options.exit_on_forward_failure && cancelled_forwarding)
1072: fatal("Error: forwarding disabled due to host key "
1073: "check failure");
1074:
1.40 markus 1075: /*
1076: * XXX Should permit the user to change to use the new id.
1077: * This could be done by converting the host key to an
1078: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1079: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1080: * accept the authentication.
1081: */
1.38 markus 1082: break;
1.132 markus 1083: case HOST_FOUND:
1084: fatal("internal error");
1085: break;
1.88 markus 1086: }
1087:
1088: if (options.check_host_ip && host_status != HOST_CHANGED &&
1089: ip_status == HOST_CHANGED) {
1.119 markus 1090: snprintf(msg, sizeof(msg),
1091: "Warning: the %s host key for '%.200s' "
1092: "differs from the key for the IP address '%.128s'"
1.229 djm 1093: "\nOffending key for IP in %s:%lu",
1094: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1095: if (host_status == HOST_OK) {
1096: len = strlen(msg);
1097: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1098: "\nMatching host key in %s:%lu",
1099: host_found->file, host_found->line);
1.119 markus 1100: }
1.285 djm 1101: if (options.strict_host_key_checking ==
1102: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1103: strlcat(msg, "\nAre you sure you want "
1104: "to continue connecting (yes/no)? ", sizeof(msg));
1105: if (!confirm(msg))
1.108 markus 1106: goto fail;
1.285 djm 1107: } else if (options.strict_host_key_checking !=
1108: SSH_STRICT_HOSTKEY_OFF) {
1109: logit("%s", msg);
1110: error("Exiting, you have requested strict checking.");
1111: goto fail;
1.119 markus 1112: } else {
1.143 djm 1113: logit("%s", msg);
1.88 markus 1114: }
1.257 djm 1115: }
1116:
1117: if (!hostkey_trusted && options.update_hostkeys) {
1118: debug("%s: hostkey not known or explicitly trusted: "
1119: "disabling UpdateHostkeys", __func__);
1120: options.update_hostkeys = 0;
1.38 markus 1121: }
1.82 provos 1122:
1.238 djm 1123: free(ip);
1124: free(host);
1.229 djm 1125: if (host_hostkeys != NULL)
1126: free_hostkeys(host_hostkeys);
1127: if (ip_hostkeys != NULL)
1128: free_hostkeys(ip_hostkeys);
1.108 markus 1129: return 0;
1130:
1131: fail:
1.220 djm 1132: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1133: /*
1134: * No matching certificate. Downgrade cert to raw key and
1135: * search normally.
1136: */
1137: debug("No matching CA found. Retry with plain key");
1.280 markus 1138: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1139: fatal("%s: sshkey_from_private: %s",
1140: __func__, ssh_err(r));
1141: if ((r = sshkey_drop_cert(raw_key)) != 0)
1142: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1143: host_key = raw_key;
1144: goto retry;
1145: }
1146: if (raw_key != NULL)
1.280 markus 1147: sshkey_free(raw_key);
1.238 djm 1148: free(ip);
1149: free(host);
1.229 djm 1150: if (host_hostkeys != NULL)
1151: free_hostkeys(host_hostkeys);
1152: if (ip_hostkeys != NULL)
1153: free_hostkeys(ip_hostkeys);
1.108 markus 1154: return -1;
1155: }
1156:
1.140 jakob 1157: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1158: int
1.279 markus 1159: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1160: {
1.267 djm 1161: u_int i;
1.250 djm 1162: int r = -1, flags = 0;
1.267 djm 1163: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1164: struct sshkey *plain = NULL;
1.229 djm 1165:
1.252 djm 1166: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1167: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1168: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1169: r = -1;
1170: goto out;
1171: }
1172:
1.267 djm 1173: if (sshkey_is_cert(host_key)) {
1174: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1175: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1176: error("%s: fingerprint CA key: %s",
1177: __func__, ssh_err(r));
1178: r = -1;
1179: goto out;
1180: }
1181: sshkey_format_cert_validity(host_key->cert,
1182: valid, sizeof(valid));
1183: debug("Server host certificate: %s %s, serial %llu "
1184: "ID \"%s\" CA %s %s valid %s",
1185: sshkey_ssh_name(host_key), fp,
1.269 djm 1186: (unsigned long long)host_key->cert->serial,
1187: host_key->cert->key_id,
1.267 djm 1188: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1189: valid);
1190: for (i = 0; i < host_key->cert->nprincipals; i++) {
1191: debug2("Server host certificate hostname: %s",
1192: host_key->cert->principals[i]);
1193: }
1194: } else {
1.276 djm 1195: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1196: }
1.252 djm 1197:
1198: if (sshkey_equal(previous_host_key, host_key)) {
1199: debug2("%s: server host key %s %s matches cached key",
1200: __func__, sshkey_type(host_key), fp);
1201: r = 0;
1202: goto out;
1203: }
1204:
1205: /* Check in RevokedHostKeys file if specified */
1206: if (options.revoked_host_keys != NULL) {
1207: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1208: switch (r) {
1209: case 0:
1210: break; /* not revoked */
1211: case SSH_ERR_KEY_REVOKED:
1212: error("Host key %s %s revoked by file %s",
1213: sshkey_type(host_key), fp,
1214: options.revoked_host_keys);
1215: r = -1;
1216: goto out;
1217: default:
1218: error("Error checking host key %s %s in "
1219: "revoked keys file %s: %s", sshkey_type(host_key),
1220: fp, options.revoked_host_keys, ssh_err(r));
1221: r = -1;
1222: goto out;
1223: }
1.250 djm 1224: }
1225:
1.247 djm 1226: if (options.verify_host_key_dns) {
1227: /*
1228: * XXX certs are not yet supported for DNS, so downgrade
1229: * them and try the plain key.
1230: */
1.252 djm 1231: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1232: goto out;
1233: if (sshkey_is_cert(plain))
1234: sshkey_drop_cert(plain);
1.247 djm 1235: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1236: if (flags & DNS_VERIFY_FOUND) {
1237: if (options.verify_host_key_dns == 1 &&
1238: flags & DNS_VERIFY_MATCH &&
1239: flags & DNS_VERIFY_SECURE) {
1.250 djm 1240: r = 0;
1.252 djm 1241: goto out;
1.247 djm 1242: }
1243: if (flags & DNS_VERIFY_MATCH) {
1244: matching_host_key_dns = 1;
1245: } else {
1.287 djm 1246: warn_changed_key(plain);
1247: error("Update the SSHFP RR in DNS "
1248: "with the new host key to get rid "
1249: "of this message.");
1.247 djm 1250: }
1.153 jakob 1251: }
1.140 jakob 1252: }
1253: }
1.250 djm 1254: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1255: options.user_hostfiles, options.num_user_hostfiles,
1256: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1257:
1.252 djm 1258: out:
1259: sshkey_free(plain);
1260: free(fp);
1.267 djm 1261: free(cafp);
1.250 djm 1262: if (r == 0 && host_key != NULL) {
1.280 markus 1263: sshkey_free(previous_host_key);
1264: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1265: }
1266:
1267: return r;
1.51 markus 1268: }
1.70 markus 1269:
1.51 markus 1270: /*
1271: * Starts a dialog with the server, and authenticates the current user on the
1272: * server. This does not need any extra privileges. The basic connection
1273: * to the server must already have been established before this is called.
1274: * If login fails, this function prints an error and never returns.
1275: * This function does not require super-user privileges.
1276: */
1277: void
1.120 markus 1278: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1279: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1280: {
1.241 djm 1281: char *host;
1.70 markus 1282: char *server_user, *local_user;
1283:
1284: local_user = xstrdup(pw->pw_name);
1285: server_user = options.user ? options.user : local_user;
1.51 markus 1286:
1287: /* Convert the user-supplied hostname into all lowercase. */
1288: host = xstrdup(orighost);
1.241 djm 1289: lowercase(host);
1.51 markus 1290:
1291: /* Exchange protocol version identification strings with the server. */
1.202 djm 1292: ssh_exchange_identification(timeout_ms);
1.51 markus 1293:
1294: /* Put the connection into non-blocking mode. */
1295: packet_set_nonblocking();
1296:
1297: /* key exchange */
1298: /* authenticate user */
1.261 dtucker 1299: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.276 djm 1300: ssh_kex2(host, hostaddr, port);
1301: ssh_userauth2(local_user, server_user, host, sensitive);
1.238 djm 1302: free(local_user);
1.97 markus 1303: }
1304:
1305: void
1306: ssh_put_password(char *password)
1307: {
1308: int size;
1309: char *padded;
1310:
1.99 deraadt 1311: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1312: packet_put_cstring(password);
1.99 deraadt 1313: return;
1314: }
1.272 deraadt 1315: size = ROUNDUP(strlen(password) + 1, 32);
1.179 djm 1316: padded = xcalloc(1, size);
1.97 markus 1317: strlcpy(padded, password, size);
1318: packet_put_string(padded, size);
1.245 djm 1319: explicit_bzero(padded, size);
1.238 djm 1320: free(padded);
1.132 markus 1321: }
1322:
1323: /* print all known host keys for a given host, but skip keys of given type */
1324: static int
1.279 markus 1325: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1326: {
1.242 djm 1327: int type[] = {
1328: KEY_RSA,
1329: KEY_DSA,
1330: KEY_ECDSA,
1331: KEY_ED25519,
1332: -1
1333: };
1.229 djm 1334: int i, ret = 0;
1335: char *fp, *ra;
1336: const struct hostkey_entry *found;
1.132 markus 1337:
1338: for (i = 0; type[i] != -1; i++) {
1339: if (type[i] == key->type)
1340: continue;
1.229 djm 1341: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1342: continue;
1.259 djm 1343: fp = sshkey_fingerprint(found->key,
1.254 djm 1344: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1345: ra = sshkey_fingerprint(found->key,
1.254 djm 1346: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1347: if (fp == NULL || ra == NULL)
1348: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1349: logit("WARNING: %s key found for host %s\n"
1350: "in %s:%lu\n"
1351: "%s key fingerprint %s.",
1352: key_type(found->key),
1353: found->host, found->file, found->line,
1354: key_type(found->key), fp);
1355: if (options.visual_host_key)
1356: logit("%s", ra);
1.238 djm 1357: free(ra);
1358: free(fp);
1.229 djm 1359: ret = 1;
1.132 markus 1360: }
1.229 djm 1361: return ret;
1.150 jakob 1362: }
1363:
1364: static void
1.279 markus 1365: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1366: {
1367: char *fp;
1368:
1.259 djm 1369: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1370: SSH_FP_DEFAULT);
1.259 djm 1371: if (fp == NULL)
1372: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1373:
1374: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1375: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1376: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1377: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1378: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1379: error("It is also possible that a host key has just been changed.");
1.150 jakob 1380: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.287 djm 1381: key_type(host_key), fp);
1.150 jakob 1382: error("Please contact your system administrator.");
1383:
1.238 djm 1384: free(fp);
1.171 reyk 1385: }
1386:
1387: /*
1388: * Execute a local command
1389: */
1390: int
1391: ssh_local_cmd(const char *args)
1392: {
1393: char *shell;
1394: pid_t pid;
1395: int status;
1.231 djm 1396: void (*osighand)(int);
1.171 reyk 1397:
1398: if (!options.permit_local_command ||
1399: args == NULL || !*args)
1400: return (1);
1401:
1.226 djm 1402: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1403: shell = _PATH_BSHELL;
1404:
1.231 djm 1405: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1406: pid = fork();
1407: if (pid == 0) {
1.232 djm 1408: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1409: debug3("Executing %s -c \"%s\"", shell, args);
1410: execl(shell, shell, "-c", args, (char *)NULL);
1411: error("Couldn't execute %s -c \"%s\": %s",
1412: shell, args, strerror(errno));
1413: _exit(1);
1414: } else if (pid == -1)
1415: fatal("fork failed: %.100s", strerror(errno));
1416: while (waitpid(pid, &status, 0) == -1)
1417: if (errno != EINTR)
1418: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1419: signal(SIGCHLD, osighand);
1.171 reyk 1420:
1421: if (!WIFEXITED(status))
1422: return (1);
1423:
1424: return (WEXITSTATUS(status));
1.266 jcs 1425: }
1426:
1427: void
1.279 markus 1428: maybe_add_key_to_agent(char *authfile, struct sshkey *private, char *comment,
1.266 jcs 1429: char *passphrase)
1430: {
1431: int auth_sock = -1, r;
1432:
1433: if (options.add_keys_to_agent == 0)
1434: return;
1435:
1436: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1437: debug3("no authentication agent, not adding key");
1438: return;
1439: }
1440:
1441: if (options.add_keys_to_agent == 2 &&
1442: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1443: debug3("user denied adding this key");
1.273 dtucker 1444: close(auth_sock);
1.266 jcs 1445: return;
1446: }
1447:
1448: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1449: (options.add_keys_to_agent == 3))) == 0)
1450: debug("identity added to agent: %s", authfile);
1451: else
1452: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1453: close(auth_sock);
1.1 deraadt 1454: }