Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.276
1.276 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.275 2017/04/30 23:11:45 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>
1.199 deraadt 29: #include <signal.h>
1.188 stevesk 30: #include <pwd.h>
1.198 stevesk 31: #include <stdio.h>
1.196 stevesk 32: #include <stdlib.h>
1.193 stevesk 33: #include <string.h>
1.192 stevesk 34: #include <unistd.h>
1.71 markus 35:
1.199 deraadt 36: #include "xmalloc.h"
1.91 markus 37: #include "ssh.h"
1.1 deraadt 38: #include "rsa.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;
1.250 djm 60: Key *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:
1.229 djm 72: static int show_other_keys(struct hostkeys *, Key *);
1.150 jakob 73: static void warn_changed_key(Key *);
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
95: ssh_proxy_fdpass_connect(const char *host, u_short port,
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. */
166: packet_set_connection(sock, sock);
167:
168: return 0;
169: }
170:
1.39 deraadt 171: /*
172: * Connect to the given ssh server using a proxy command.
173: */
1.109 itojun 174: static int
1.124 markus 175: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 176: {
1.239 djm 177: char *command_string;
1.38 markus 178: int pin[2], pout[2];
1.69 deraadt 179: pid_t pid;
1.239 djm 180: char *shell;
1.237 markus 181:
1.226 djm 182: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 183: shell = _PATH_BSHELL;
1.38 markus 184:
185: /* Create pipes for communicating with the proxy. */
186: if (pipe(pin) < 0 || pipe(pout) < 0)
187: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 188: strerror(errno));
1.38 markus 189:
1.239 djm 190: command_string = expand_proxy_command(proxy_command, options.user,
191: host, port);
1.38 markus 192: debug("Executing proxy command: %.500s", command_string);
193:
194: /* Fork and execute the proxy command. */
195: if ((pid = fork()) == 0) {
196: char *argv[10];
197:
198: /* Child. Permanently give up superuser privileges. */
1.184 markus 199: permanently_drop_suid(original_real_uid);
1.38 markus 200:
201: /* Redirect stdin and stdout. */
202: close(pin[1]);
203: if (pin[0] != 0) {
204: if (dup2(pin[0], 0) < 0)
205: perror("dup2 stdin");
206: close(pin[0]);
207: }
208: close(pout[0]);
209: if (dup2(pout[1], 1) < 0)
210: perror("dup2 stdout");
211: /* Cannot be 1 because pin allocated two descriptors. */
212: close(pout[1]);
213:
214: /* Stderr is left as it is so that error messages get
215: printed on the user's terminal. */
1.201 djm 216: argv[0] = shell;
1.38 markus 217: argv[1] = "-c";
218: argv[2] = command_string;
219: argv[3] = NULL;
220:
221: /* Execute the proxy command. Note that we gave up any
222: extra privileges above. */
1.232 djm 223: signal(SIGPIPE, SIG_DFL);
1.89 markus 224: execv(argv[0], argv);
225: perror(argv[0]);
1.38 markus 226: exit(1);
227: }
228: /* Parent. */
229: if (pid < 0)
230: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 231: else
232: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 233:
234: /* Close child side of the descriptors. */
235: close(pin[0]);
236: close(pout[1]);
237:
238: /* Free the command name. */
1.238 djm 239: free(command_string);
1.38 markus 240:
241: /* Set the connection file descriptors. */
242: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 243:
1.110 markus 244: /* Indicate OK return */
245: return 0;
1.227 djm 246: }
247:
248: void
249: ssh_kill_proxy_command(void)
250: {
251: /*
252: * Send SIGHUP to proxy command if used. We don't wait() in
253: * case it hangs and instead rely on init to reap the child
254: */
255: if (proxy_command_pid > 1)
1.228 djm 256: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 257: }
258:
1.39 deraadt 259: /*
260: * Creates a (possibly privileged) socket for use as the ssh connection.
261: */
1.109 itojun 262: static int
1.139 markus 263: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 264: {
1.240 djm 265: int sock, r, gaierr;
1.246 djm 266: struct addrinfo hints, *res = NULL;
1.1 deraadt 267:
1.217 dtucker 268: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 269: if (sock < 0) {
1.240 djm 270: error("socket: %s", strerror(errno));
1.216 dtucker 271: return -1;
272: }
273: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 274:
275: /* Bind the socket to an alternative local IP address */
1.240 djm 276: if (options.bind_address == NULL && !privileged)
1.105 markus 277: return sock;
278:
1.246 djm 279: if (options.bind_address) {
280: memset(&hints, 0, sizeof(hints));
281: hints.ai_family = ai->ai_family;
282: hints.ai_socktype = ai->ai_socktype;
283: hints.ai_protocol = ai->ai_protocol;
284: hints.ai_flags = AI_PASSIVE;
285: gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
286: if (gaierr) {
287: error("getaddrinfo: %s: %s", options.bind_address,
288: ssh_gai_strerror(gaierr));
289: close(sock);
290: return -1;
291: }
1.105 markus 292: }
1.240 djm 293: /*
294: * If we are running as root and want to connect to a privileged
295: * port, bind our own socket to a privileged port.
296: */
297: if (privileged) {
298: PRIV_START;
1.246 djm 299: r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
1.240 djm 300: PRIV_END;
301: if (r < 0) {
302: error("bindresvport_sa: af=%d %s", ai->ai_family,
303: strerror(errno));
304: goto fail;
305: }
306: } else {
307: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
308: error("bind: %s: %s", options.bind_address,
309: strerror(errno));
310: fail:
311: close(sock);
312: freeaddrinfo(res);
313: return -1;
314: }
1.38 markus 315: }
1.246 djm 316: if (res != NULL)
317: freeaddrinfo(res);
1.38 markus 318: return sock;
1.1 deraadt 319: }
320:
1.141 djm 321: static int
322: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 323: socklen_t addrlen, int *timeoutp)
1.141 djm 324: {
325: fd_set *fdset;
1.202 djm 326: struct timeval tv, t_start;
1.141 djm 327: socklen_t optlen;
1.179 djm 328: int optval, rc, result = -1;
1.141 djm 329:
1.202 djm 330: gettimeofday(&t_start, NULL);
331:
332: if (*timeoutp <= 0) {
333: result = connect(sockfd, serv_addr, addrlen);
334: goto done;
335: }
1.141 djm 336:
1.156 djm 337: set_nonblock(sockfd);
1.141 djm 338: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 339: if (rc == 0) {
340: unset_nonblock(sockfd);
1.202 djm 341: result = 0;
342: goto done;
343: }
344: if (errno != EINPROGRESS) {
345: result = -1;
346: goto done;
1.156 djm 347: }
1.141 djm 348:
1.263 deraadt 349: fdset = xcalloc(howmany(sockfd + 1, NFDBITS),
1.179 djm 350: sizeof(fd_mask));
1.141 djm 351: FD_SET(sockfd, fdset);
1.202 djm 352: ms_to_timeval(&tv, *timeoutp);
1.141 djm 353:
1.162 deraadt 354: for (;;) {
1.141 djm 355: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
356: if (rc != -1 || errno != EINTR)
357: break;
358: }
359:
1.162 deraadt 360: switch (rc) {
1.141 djm 361: case 0:
362: /* Timed out */
363: errno = ETIMEDOUT;
1.142 djm 364: break;
1.141 djm 365: case -1:
366: /* Select error */
1.154 djm 367: debug("select: %s", strerror(errno));
1.142 djm 368: break;
1.141 djm 369: case 1:
370: /* Completed or failed */
371: optval = 0;
372: optlen = sizeof(optval);
1.154 djm 373: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 374: &optlen) == -1) {
1.154 djm 375: debug("getsockopt: %s", strerror(errno));
1.142 djm 376: break;
1.148 markus 377: }
1.141 djm 378: if (optval != 0) {
379: errno = optval;
1.142 djm 380: break;
1.141 djm 381: }
1.142 djm 382: result = 0;
1.156 djm 383: unset_nonblock(sockfd);
1.141 djm 384: break;
385: default:
386: /* Should not occur */
387: fatal("Bogus return (%d) from select()", rc);
388: }
389:
1.238 djm 390: free(fdset);
1.202 djm 391:
392: done:
393: if (result == 0 && *timeoutp > 0) {
394: ms_subtract_diff(&t_start, timeoutp);
395: if (*timeoutp <= 0) {
396: errno = ETIMEDOUT;
397: result = -1;
398: }
399: }
400:
1.142 djm 401: return (result);
1.141 djm 402: }
403:
1.39 deraadt 404: /*
1.49 markus 405: * Opens a TCP/IP connection to the remote server on the given host.
406: * The address of the remote host will be returned in hostaddr.
1.124 markus 407: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 408: * a privileged port will be allocated to make the connection.
1.124 markus 409: * This requires super-user privileges if needpriv is true.
1.39 deraadt 410: * Connection_attempts specifies the maximum number of tries (one per
411: * second). If proxy_command is non-NULL, it specifies the command (with %h
412: * and %p substituted for host and port, respectively) to use to contact
413: * the daemon.
414: */
1.241 djm 415: static int
416: ssh_connect_direct(const char *host, struct addrinfo *aitop,
417: struct sockaddr_storage *hostaddr, u_short port, int family,
418: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
1.1 deraadt 419: {
1.90 markus 420: int on = 1;
1.49 markus 421: int sock = -1, attempt;
1.90 markus 422: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 423: struct addrinfo *ai;
1.38 markus 424:
1.265 djm 425: debug2("%s: needpriv %d", __func__, needpriv);
1.268 djm 426: memset(ntop, 0, sizeof(ntop));
427: memset(strport, 0, sizeof(strport));
1.38 markus 428:
1.181 markus 429: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 430: if (attempt > 0) {
431: /* Sleep a moment before retrying. */
432: sleep(1);
1.38 markus 433: debug("Trying again...");
1.200 markus 434: }
1.181 markus 435: /*
436: * Loop through addresses for this host, and try each one in
437: * sequence until the connection succeeds.
438: */
1.49 markus 439: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 440: if (ai->ai_family != AF_INET &&
441: ai->ai_family != AF_INET6)
1.49 markus 442: continue;
443: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
444: ntop, sizeof(ntop), strport, sizeof(strport),
445: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.265 djm 446: error("%s: getnameinfo failed", __func__);
1.49 markus 447: continue;
448: }
449: debug("Connecting to %.200s [%.100s] port %s.",
450: host, ntop, strport);
451:
452: /* Create a socket for connecting. */
1.139 markus 453: sock = ssh_create_socket(needpriv, ai);
1.49 markus 454: if (sock < 0)
1.110 markus 455: /* Any error is already output */
1.49 markus 456: continue;
457:
1.141 djm 458: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 459: timeout_ms) >= 0) {
1.49 markus 460: /* Successful connection. */
1.102 markus 461: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 462: break;
1.49 markus 463: } else {
1.131 itojun 464: debug("connect to address %s port %s: %s",
465: ntop, strport, strerror(errno));
1.38 markus 466: close(sock);
1.181 markus 467: sock = -1;
1.38 markus 468: }
469: }
1.181 markus 470: if (sock != -1)
1.49 markus 471: break; /* Successful connection. */
1.38 markus 472: }
1.49 markus 473:
1.38 markus 474: /* Return failure if we didn't get a successful connection. */
1.181 markus 475: if (sock == -1) {
1.159 markus 476: error("ssh: connect to host %s port %s: %s",
1.130 itojun 477: host, strport, strerror(errno));
1.159 markus 478: return (-1);
1.130 itojun 479: }
1.38 markus 480:
481: debug("Connection established.");
1.90 markus 482:
1.155 markus 483: /* Set SO_KEEPALIVE if requested. */
1.202 djm 484: if (want_keepalive &&
1.90 markus 485: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
486: sizeof(on)) < 0)
487: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 488:
489: /* Set the connection. */
490: packet_set_connection(sock, sock);
1.1 deraadt 491:
1.110 markus 492: return 0;
1.59 markus 493: }
494:
1.241 djm 495: int
496: ssh_connect(const char *host, struct addrinfo *addrs,
497: struct sockaddr_storage *hostaddr, u_short port, int family,
498: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
499: {
500: if (options.proxy_command == NULL) {
501: return ssh_connect_direct(host, addrs, hostaddr, port, family,
502: connection_attempts, timeout_ms, want_keepalive, needpriv);
503: } else if (strcmp(options.proxy_command, "-") == 0) {
504: packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
505: return 0; /* Always succeeds */
506: } else if (options.proxy_use_fdpass) {
507: return ssh_proxy_fdpass_connect(host, port,
508: options.proxy_command);
509: }
510: return ssh_proxy_connect(host, port, options.proxy_command);
511: }
512:
1.235 djm 513: static void
514: send_client_banner(int connection_out, int minor1)
515: {
516: /* Send our own protocol version identification. */
1.276 ! djm 517: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
! 518: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
1.270 markus 519: if (atomicio(vwrite, connection_out, client_version_string,
1.235 djm 520: strlen(client_version_string)) != strlen(client_version_string))
521: fatal("write: %.100s", strerror(errno));
522: chop(client_version_string);
523: debug("Local version string %.100s", client_version_string);
524: }
525:
1.43 markus 526: /*
1.39 deraadt 527: * Waits for the server identification string, and sends our own
528: * identification string.
529: */
1.213 andreas 530: void
1.202 djm 531: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 532: {
1.38 markus 533: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 534: int remote_major, remote_minor, mismatch;
1.38 markus 535: int connection_in = packet_get_connection_in();
536: int connection_out = packet_get_connection_out();
1.275 djm 537: int client_banner_sent = 0;
1.185 djm 538: u_int i, n;
1.202 djm 539: size_t len;
540: int fdsetsz, remaining, rc;
541: struct timeval t_start, t_remaining;
542: fd_set *fdset;
543:
544: fdsetsz = howmany(connection_in + 1, NFDBITS) * sizeof(fd_mask);
545: fdset = xcalloc(1, fdsetsz);
1.38 markus 546:
1.275 djm 547: send_client_banner(connection_out, 0);
548: client_banner_sent = 1;
1.235 djm 549:
1.163 avsm 550: /* Read other side's version identification. */
1.202 djm 551: remaining = timeout_ms;
1.185 djm 552: for (n = 0;;) {
1.75 markus 553: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 554: if (timeout_ms > 0) {
555: gettimeofday(&t_start, NULL);
556: ms_to_timeval(&t_remaining, remaining);
557: FD_SET(connection_in, fdset);
558: rc = select(connection_in + 1, fdset, NULL,
559: fdset, &t_remaining);
560: ms_subtract_diff(&t_start, &remaining);
561: if (rc == 0 || remaining <= 0)
562: fatal("Connection timed out during "
563: "banner exchange");
564: if (rc == -1) {
565: if (errno == EINTR)
566: continue;
567: fatal("ssh_exchange_identification: "
568: "select: %s", strerror(errno));
569: }
570: }
571:
1.270 markus 572: len = atomicio(read, connection_in, &buf[i], 1);
1.163 avsm 573:
1.167 djm 574: if (len != 1 && errno == EPIPE)
1.202 djm 575: fatal("ssh_exchange_identification: "
576: "Connection closed by remote host");
1.163 avsm 577: else if (len != 1)
1.202 djm 578: fatal("ssh_exchange_identification: "
579: "read: %.100s", strerror(errno));
1.75 markus 580: if (buf[i] == '\r') {
581: buf[i] = '\n';
582: buf[i + 1] = 0;
583: continue; /**XXX wait for \n */
584: }
585: if (buf[i] == '\n') {
586: buf[i + 1] = 0;
587: break;
588: }
1.185 djm 589: if (++n > 65536)
1.202 djm 590: fatal("ssh_exchange_identification: "
591: "No banner received");
1.38 markus 592: }
1.75 markus 593: buf[sizeof(buf) - 1] = 0;
1.76 markus 594: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 595: break;
1.75 markus 596: debug("ssh_exchange_identification: %s", buf);
1.38 markus 597: }
1.59 markus 598: server_version_string = xstrdup(buf);
1.238 djm 599: free(fdset);
1.38 markus 600:
1.40 markus 601: /*
602: * Check that the versions match. In future this might accept
603: * several versions and set appropriate flags to handle them.
604: */
1.59 markus 605: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
606: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 607: fatal("Bad remote protocol version identification: '%.100s'", buf);
608: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 609: remote_major, remote_minor, remote_version);
1.38 markus 610:
1.255 markus 611: active_state->compat = compat_datafellows(remote_version);
1.64 markus 612: mismatch = 0;
1.59 markus 613:
1.116 deraadt 614: switch (remote_major) {
1.276 ! djm 615: case 2:
! 616: break;
1.64 markus 617: case 1:
1.276 ! djm 618: if (remote_minor != 99)
1.64 markus 619: mismatch = 1;
620: break;
1.68 markus 621: default:
1.64 markus 622: mismatch = 1;
623: break;
1.38 markus 624: }
1.64 markus 625: if (mismatch)
1.38 markus 626: fatal("Protocol major versions differ: %d vs. %d",
1.275 djm 627: PROTOCOL_MAJOR_2, remote_major);
1.244 djm 628: if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
629: fatal("Server version \"%.100s\" uses unsafe key agreement; "
630: "refusing connection", remote_version);
1.243 djm 631: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
632: logit("Server version \"%.100s\" uses unsafe RSA signature "
633: "scheme; disabling use of RSA keys", remote_version);
1.59 markus 634: chop(server_version_string);
1.1 deraadt 635: }
636:
1.96 markus 637: /* defaults to 'no' */
1.109 itojun 638: static int
1.112 markus 639: confirm(const char *prompt)
1.1 deraadt 640: {
1.119 markus 641: const char *msg, *again = "Please type 'yes' or 'no': ";
642: char *p;
643: int ret = -1;
1.96 markus 644:
645: if (options.batch_mode)
646: return 0;
1.119 markus 647: for (msg = prompt;;msg = again) {
648: p = read_passphrase(msg, RP_ECHO);
649: if (p == NULL ||
650: (p[0] == '\0') || (p[0] == '\n') ||
651: strncasecmp(p, "no", 2) == 0)
652: ret = 0;
1.127 markus 653: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 654: ret = 1;
1.238 djm 655: free(p);
1.119 markus 656: if (ret != -1)
657: return ret;
1.1 deraadt 658: }
659: }
660:
1.219 djm 661: static int
662: check_host_cert(const char *host, const Key *host_key)
663: {
664: const char *reason;
665:
666: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
667: error("%s", reason);
668: return 0;
669: }
1.249 djm 670: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 671: error("Certificate for %s contains unsupported "
672: "critical options(s)", host);
1.219 djm 673: return 0;
674: }
675: return 1;
676: }
677:
1.229 djm 678: static int
679: sockaddr_is_local(struct sockaddr *hostaddr)
680: {
681: switch (hostaddr->sa_family) {
682: case AF_INET:
683: return (ntohl(((struct sockaddr_in *)hostaddr)->
684: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
685: case AF_INET6:
686: return IN6_IS_ADDR_LOOPBACK(
687: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
688: default:
689: return 0;
690: }
691: }
692:
693: /*
694: * Prepare the hostname and ip address strings that are used to lookup
695: * host keys in known_hosts files. These may have a port number appended.
696: */
697: void
698: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
699: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
700: {
701: char ntop[NI_MAXHOST];
702:
703: /*
704: * We don't have the remote ip-address for connections
705: * using a proxy command
706: */
707: if (hostfile_ipaddr != NULL) {
708: if (options.proxy_command == NULL) {
709: if (getnameinfo(hostaddr, hostaddr->sa_len,
710: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 711: fatal("%s: getnameinfo failed", __func__);
1.229 djm 712: *hostfile_ipaddr = put_host_port(ntop, port);
713: } else {
714: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
715: "command>");
716: }
717: }
718:
719: /*
720: * Allow the user to record the key under a different name or
721: * differentiate a non-standard port. This is useful for ssh
722: * tunneling over forwarded connections or if you run multiple
723: * sshd's on different ports on the same machine.
724: */
725: if (hostfile_hostname != NULL) {
726: if (options.host_key_alias != NULL) {
727: *hostfile_hostname = xstrdup(options.host_key_alias);
728: debug("using hostkeyalias: %s", *hostfile_hostname);
729: } else {
730: *hostfile_hostname = put_host_port(hostname, port);
731: }
732: }
733: }
734:
1.39 deraadt 735: /*
1.108 markus 736: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 737: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 738: */
1.197 dtucker 739: #define RDRW 0
740: #define RDONLY 1
741: #define ROQUIET 2
1.109 itojun 742: static int
1.197 dtucker 743: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.234 djm 744: Key *host_key, int readonly,
745: char **user_hostfiles, u_int num_user_hostfiles,
746: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 747: {
1.234 djm 748: HostStatus host_status;
749: HostStatus ip_status;
1.229 djm 750: Key *raw_key = NULL;
1.189 dtucker 751: char *ip = NULL, *host = NULL;
1.204 grunk 752: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 753: char msg[1024];
1.234 djm 754: const char *type;
755: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 756: int len, cancelled_forwarding = 0;
1.234 djm 757: int local = sockaddr_is_local(hostaddr);
758: int r, want_cert = key_is_cert(host_key), host_ip_differ = 0;
1.257 djm 759: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 760: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 761: u_int i;
1.49 markus 762:
763: /*
764: * Force accepting of the host key for loopback/localhost. The
765: * problem is that if the home directory is NFS-mounted to multiple
766: * machines, localhost will refer to a different machine in each of
767: * them, and the user will get bogus HOST_CHANGED warnings. This
768: * essentially disables host authentication for localhost; however,
769: * this is probably not a real problem.
770: */
1.111 markus 771: if (options.no_host_authentication_for_localhost == 1 && local &&
772: options.host_key_alias == NULL) {
1.88 markus 773: debug("Forcing accepting of host key for "
774: "loopback/localhost.");
1.108 markus 775: return 0;
1.49 markus 776: }
1.42 markus 777:
778: /*
1.229 djm 779: * Prepare the hostname and address strings used for hostkey lookup.
780: * In some cases, these will have a port number appended.
1.42 markus 781: */
1.229 djm 782: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 783:
784: /*
1.88 markus 785: * Turn off check_host_ip if the connection is to localhost, via proxy
786: * command or if we don't have a hostname to compare with
787: */
1.189 dtucker 788: if (options.check_host_ip && (local ||
789: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 790: options.check_host_ip = 0;
1.86 markus 791:
1.229 djm 792: host_hostkeys = init_hostkeys();
1.234 djm 793: for (i = 0; i < num_user_hostfiles; i++)
794: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
795: for (i = 0; i < num_system_hostfiles; i++)
796: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 797:
798: ip_hostkeys = NULL;
799: if (!want_cert && options.check_host_ip) {
800: ip_hostkeys = init_hostkeys();
1.234 djm 801: for (i = 0; i < num_user_hostfiles; i++)
802: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
803: for (i = 0; i < num_system_hostfiles; i++)
804: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 805: }
1.38 markus 806:
1.219 djm 807: retry:
1.229 djm 808: /* Reload these as they may have changed on cert->key downgrade */
1.219 djm 809: want_cert = key_is_cert(host_key);
810: type = key_type(host_key);
811:
1.46 markus 812: /*
1.170 djm 813: * Check if the host key is present in the user's list of known
1.40 markus 814: * hosts or in the systemwide list.
815: */
1.229 djm 816: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
817: &host_found);
818:
1.40 markus 819: /*
820: * Also perform check for the ip address, skip the check if we are
1.219 djm 821: * localhost, looking for a certificate, or the hostname was an ip
822: * address to begin with.
1.40 markus 823: */
1.229 djm 824: if (!want_cert && ip_hostkeys != NULL) {
825: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
826: &ip_found);
1.38 markus 827: if (host_status == HOST_CHANGED &&
1.229 djm 828: (ip_status != HOST_CHANGED ||
829: (ip_found != NULL &&
830: !key_equal(ip_found->key, host_found->key))))
1.38 markus 831: host_ip_differ = 1;
832: } else
833: ip_status = host_status;
834:
835: switch (host_status) {
836: case HOST_OK:
837: /* The host is known and the key matches. */
1.219 djm 838: debug("Host '%.200s' is known and matches the %s host %s.",
839: host, type, want_cert ? "certificate" : "key");
1.229 djm 840: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
841: host_found->file, host_found->line);
1.219 djm 842: if (want_cert && !check_host_cert(hostname, host_key))
843: goto fail;
1.88 markus 844: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 845: if (readonly || want_cert)
1.138 itojun 846: logit("%s host key for IP address "
1.108 markus 847: "'%.128s' not in list of known hosts.",
848: type, ip);
1.234 djm 849: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 850: host_key, options.hash_known_hosts))
1.138 itojun 851: logit("Failed to add the %s host key for IP "
1.108 markus 852: "address '%.128s' to the list of known "
1.262 dtucker 853: "hosts (%.500s).", type, ip,
1.234 djm 854: user_hostfiles[0]);
1.88 markus 855: else
1.138 itojun 856: logit("Warning: Permanently added the %s host "
1.108 markus 857: "key for IP address '%.128s' to the list "
858: "of known hosts.", type, ip);
1.209 grunk 859: } else if (options.visual_host_key) {
1.259 djm 860: fp = sshkey_fingerprint(host_key,
1.254 djm 861: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 862: ra = sshkey_fingerprint(host_key,
1.254 djm 863: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 864: if (fp == NULL || ra == NULL)
865: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 866: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 867: free(ra);
868: free(fp);
1.38 markus 869: }
1.257 djm 870: hostkey_trusted = 1;
1.38 markus 871: break;
872: case HOST_NEW:
1.197 dtucker 873: if (options.host_key_alias == NULL && port != 0 &&
874: port != SSH_DEFAULT_PORT) {
875: debug("checking without port identifier");
1.212 stevesk 876: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 877: ROQUIET, user_hostfiles, num_user_hostfiles,
878: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 879: debug("found matching key w/out port");
880: break;
881: }
882: }
1.219 djm 883: if (readonly || want_cert)
1.108 markus 884: goto fail;
1.38 markus 885: /* The host is new. */
886: if (options.strict_host_key_checking == 1) {
1.108 markus 887: /*
888: * User has requested strict host key checking. We
889: * will not add the host key automatically. The only
890: * alternative left is to abort.
891: */
892: error("No %s host key is known for %.200s and you "
893: "have requested strict checking.", type, host);
894: goto fail;
1.38 markus 895: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 896: char msg1[1024], msg2[1024];
897:
1.229 djm 898: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 899: snprintf(msg1, sizeof(msg1),
1.168 djm 900: "\nbut keys of different type are already"
901: " known for this host.");
1.145 jakob 902: else
903: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 904: /* The default */
1.259 djm 905: fp = sshkey_fingerprint(host_key,
1.254 djm 906: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 907: ra = sshkey_fingerprint(host_key,
1.254 djm 908: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 909: if (fp == NULL || ra == NULL)
910: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 911: msg2[0] = '\0';
912: if (options.verify_host_key_dns) {
1.153 jakob 913: if (matching_host_key_dns)
1.145 jakob 914: snprintf(msg2, sizeof(msg2),
915: "Matching host key fingerprint"
916: " found in DNS.\n");
917: else
918: snprintf(msg2, sizeof(msg2),
919: "No matching host key fingerprint"
920: " found in DNS.\n");
921: }
1.119 markus 922: snprintf(msg, sizeof(msg),
1.108 markus 923: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 924: "established%s\n"
1.209 grunk 925: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 926: "Are you sure you want to continue connecting "
1.132 markus 927: "(yes/no)? ",
1.209 grunk 928: host, ip, msg1, type, fp,
929: options.visual_host_key ? "\n" : "",
930: options.visual_host_key ? ra : "",
931: msg2);
1.238 djm 932: free(ra);
933: free(fp);
1.119 markus 934: if (!confirm(msg))
1.108 markus 935: goto fail;
1.257 djm 936: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 937: }
1.161 djm 938: /*
939: * If not in strict mode, add the key automatically to the
940: * local known_hosts file.
941: */
1.88 markus 942: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 943: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 944: hostp = hostline;
1.161 djm 945: if (options.hash_known_hosts) {
946: /* Add hash of host and IP separately */
1.234 djm 947: r = add_host_to_hostfile(user_hostfiles[0],
948: host, host_key, options.hash_known_hosts) &&
949: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 950: host_key, options.hash_known_hosts);
951: } else {
952: /* Add unhashed "host,ip" */
1.234 djm 953: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 954: hostline, host_key,
955: options.hash_known_hosts);
956: }
957: } else {
1.234 djm 958: r = add_host_to_hostfile(user_hostfiles[0], host,
959: host_key, options.hash_known_hosts);
1.38 markus 960: hostp = host;
1.161 djm 961: }
1.38 markus 962:
1.161 djm 963: if (!r)
1.138 itojun 964: logit("Failed to add the host to the list of known "
1.234 djm 965: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 966: else
1.138 itojun 967: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 968: "list of known hosts.", hostp, type);
1.38 markus 969: break;
1.220 djm 970: case HOST_REVOKED:
971: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
972: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
973: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
974: error("The %s host key for %s is marked as revoked.", type, host);
975: error("This could mean that a stolen key is being used to");
976: error("impersonate this host.");
977:
978: /*
979: * If strict host key checking is in use, the user will have
980: * to edit the key manually and we can only abort.
981: */
982: if (options.strict_host_key_checking) {
983: error("%s host key for %.200s was revoked and you have "
984: "requested strict checking.", type, host);
985: goto fail;
986: }
987: goto continue_unsafe;
988:
1.38 markus 989: case HOST_CHANGED:
1.219 djm 990: if (want_cert) {
991: /*
992: * This is only a debug() since it is valid to have
993: * CAs with wildcard DNS matches that don't match
994: * all hosts that one might visit.
995: */
996: debug("Host certificate authority does not "
1.229 djm 997: "match %s in %s:%lu", CA_MARKER,
998: host_found->file, host_found->line);
1.219 djm 999: goto fail;
1000: }
1.197 dtucker 1001: if (readonly == ROQUIET)
1002: goto fail;
1.38 markus 1003: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 1004: char *key_msg;
1.38 markus 1005: if (ip_status == HOST_NEW)
1.158 avsm 1006: key_msg = "is unknown";
1.38 markus 1007: else if (ip_status == HOST_OK)
1.158 avsm 1008: key_msg = "is unchanged";
1.38 markus 1009: else
1.158 avsm 1010: key_msg = "has a different value";
1.38 markus 1011: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1012: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
1013: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 1014: error("The %s host key for %s has changed,", type, host);
1.208 ian 1015: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 1016: error("%s. This could either mean that", key_msg);
1.38 markus 1017: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1018: error("and its host key have changed at the same time.");
1.88 markus 1019: if (ip_status != HOST_NEW)
1.229 djm 1020: error("Offending key for IP in %s:%lu",
1021: ip_found->file, ip_found->line);
1.38 markus 1022: }
1023: /* The host key has changed. */
1.150 jakob 1024: warn_changed_key(host_key);
1.38 markus 1025: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1026: user_hostfiles[0]);
1.229 djm 1027: error("Offending %s key in %s:%lu", key_type(host_found->key),
1028: host_found->file, host_found->line);
1.38 markus 1029:
1.40 markus 1030: /*
1031: * If strict host key checking is in use, the user will have
1032: * to edit the key manually and we can only abort.
1033: */
1.108 markus 1034: if (options.strict_host_key_checking) {
1035: error("%s host key for %.200s has changed and you have "
1036: "requested strict checking.", type, host);
1037: goto fail;
1038: }
1.38 markus 1039:
1.220 djm 1040: continue_unsafe:
1.40 markus 1041: /*
1042: * If strict host key checking has not been requested, allow
1.144 djm 1043: * the connection but without MITM-able authentication or
1.194 stevesk 1044: * forwarding.
1.40 markus 1045: */
1.38 markus 1046: if (options.password_authentication) {
1.108 markus 1047: error("Password authentication is disabled to avoid "
1048: "man-in-the-middle attacks.");
1.38 markus 1049: options.password_authentication = 0;
1.210 dtucker 1050: cancelled_forwarding = 1;
1.144 djm 1051: }
1052: if (options.kbd_interactive_authentication) {
1053: error("Keyboard-interactive authentication is disabled"
1054: " to avoid man-in-the-middle attacks.");
1055: options.kbd_interactive_authentication = 0;
1056: options.challenge_response_authentication = 0;
1.210 dtucker 1057: cancelled_forwarding = 1;
1.144 djm 1058: }
1059: if (options.challenge_response_authentication) {
1060: error("Challenge/response authentication is disabled"
1061: " to avoid man-in-the-middle attacks.");
1062: options.challenge_response_authentication = 0;
1.210 dtucker 1063: cancelled_forwarding = 1;
1.38 markus 1064: }
1065: if (options.forward_agent) {
1.108 markus 1066: error("Agent forwarding is disabled to avoid "
1067: "man-in-the-middle attacks.");
1.38 markus 1068: options.forward_agent = 0;
1.210 dtucker 1069: cancelled_forwarding = 1;
1.83 markus 1070: }
1071: if (options.forward_x11) {
1.108 markus 1072: error("X11 forwarding is disabled to avoid "
1073: "man-in-the-middle attacks.");
1.83 markus 1074: options.forward_x11 = 0;
1.210 dtucker 1075: cancelled_forwarding = 1;
1.83 markus 1076: }
1.108 markus 1077: if (options.num_local_forwards > 0 ||
1078: options.num_remote_forwards > 0) {
1079: error("Port forwarding is disabled to avoid "
1080: "man-in-the-middle attacks.");
1081: options.num_local_forwards =
1.118 deraadt 1082: options.num_remote_forwards = 0;
1.210 dtucker 1083: cancelled_forwarding = 1;
1.194 stevesk 1084: }
1085: if (options.tun_open != SSH_TUNMODE_NO) {
1086: error("Tunnel forwarding is disabled to avoid "
1087: "man-in-the-middle attacks.");
1088: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1089: cancelled_forwarding = 1;
1.38 markus 1090: }
1.210 dtucker 1091: if (options.exit_on_forward_failure && cancelled_forwarding)
1092: fatal("Error: forwarding disabled due to host key "
1093: "check failure");
1094:
1.40 markus 1095: /*
1096: * XXX Should permit the user to change to use the new id.
1097: * This could be done by converting the host key to an
1098: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1099: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1100: * accept the authentication.
1101: */
1.38 markus 1102: break;
1.132 markus 1103: case HOST_FOUND:
1104: fatal("internal error");
1105: break;
1.88 markus 1106: }
1107:
1108: if (options.check_host_ip && host_status != HOST_CHANGED &&
1109: ip_status == HOST_CHANGED) {
1.119 markus 1110: snprintf(msg, sizeof(msg),
1111: "Warning: the %s host key for '%.200s' "
1112: "differs from the key for the IP address '%.128s'"
1.229 djm 1113: "\nOffending key for IP in %s:%lu",
1114: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1115: if (host_status == HOST_OK) {
1116: len = strlen(msg);
1117: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1118: "\nMatching host key in %s:%lu",
1119: host_found->file, host_found->line);
1.119 markus 1120: }
1.88 markus 1121: if (options.strict_host_key_checking == 1) {
1.143 djm 1122: logit("%s", msg);
1.108 markus 1123: error("Exiting, you have requested strict checking.");
1124: goto fail;
1.88 markus 1125: } else if (options.strict_host_key_checking == 2) {
1.119 markus 1126: strlcat(msg, "\nAre you sure you want "
1127: "to continue connecting (yes/no)? ", sizeof(msg));
1128: if (!confirm(msg))
1.108 markus 1129: goto fail;
1.119 markus 1130: } else {
1.143 djm 1131: logit("%s", msg);
1.88 markus 1132: }
1.257 djm 1133: }
1134:
1135: if (!hostkey_trusted && options.update_hostkeys) {
1136: debug("%s: hostkey not known or explicitly trusted: "
1137: "disabling UpdateHostkeys", __func__);
1138: options.update_hostkeys = 0;
1.38 markus 1139: }
1.82 provos 1140:
1.238 djm 1141: free(ip);
1142: free(host);
1.229 djm 1143: if (host_hostkeys != NULL)
1144: free_hostkeys(host_hostkeys);
1145: if (ip_hostkeys != NULL)
1146: free_hostkeys(ip_hostkeys);
1.108 markus 1147: return 0;
1148:
1149: fail:
1.220 djm 1150: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1151: /*
1152: * No matching certificate. Downgrade cert to raw key and
1153: * search normally.
1154: */
1155: debug("No matching CA found. Retry with plain key");
1156: raw_key = key_from_private(host_key);
1157: if (key_drop_cert(raw_key) != 0)
1158: fatal("Couldn't drop certificate");
1159: host_key = raw_key;
1160: goto retry;
1161: }
1162: if (raw_key != NULL)
1163: key_free(raw_key);
1.238 djm 1164: free(ip);
1165: free(host);
1.229 djm 1166: if (host_hostkeys != NULL)
1167: free_hostkeys(host_hostkeys);
1168: if (ip_hostkeys != NULL)
1169: free_hostkeys(ip_hostkeys);
1.108 markus 1170: return -1;
1171: }
1172:
1.140 jakob 1173: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1174: int
1175: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
1176: {
1.267 djm 1177: u_int i;
1.250 djm 1178: int r = -1, flags = 0;
1.267 djm 1179: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1180: struct sshkey *plain = NULL;
1.229 djm 1181:
1.252 djm 1182: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1183: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1184: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1185: r = -1;
1186: goto out;
1187: }
1188:
1.267 djm 1189: if (sshkey_is_cert(host_key)) {
1190: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1191: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1192: error("%s: fingerprint CA key: %s",
1193: __func__, ssh_err(r));
1194: r = -1;
1195: goto out;
1196: }
1197: sshkey_format_cert_validity(host_key->cert,
1198: valid, sizeof(valid));
1199: debug("Server host certificate: %s %s, serial %llu "
1200: "ID \"%s\" CA %s %s valid %s",
1201: sshkey_ssh_name(host_key), fp,
1.269 djm 1202: (unsigned long long)host_key->cert->serial,
1203: host_key->cert->key_id,
1.267 djm 1204: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1205: valid);
1206: for (i = 0; i < host_key->cert->nprincipals; i++) {
1207: debug2("Server host certificate hostname: %s",
1208: host_key->cert->principals[i]);
1209: }
1210: } else {
1.276 ! djm 1211: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1212: }
1.252 djm 1213:
1214: if (sshkey_equal(previous_host_key, host_key)) {
1215: debug2("%s: server host key %s %s matches cached key",
1216: __func__, sshkey_type(host_key), fp);
1217: r = 0;
1218: goto out;
1219: }
1220:
1221: /* Check in RevokedHostKeys file if specified */
1222: if (options.revoked_host_keys != NULL) {
1223: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1224: switch (r) {
1225: case 0:
1226: break; /* not revoked */
1227: case SSH_ERR_KEY_REVOKED:
1228: error("Host key %s %s revoked by file %s",
1229: sshkey_type(host_key), fp,
1230: options.revoked_host_keys);
1231: r = -1;
1232: goto out;
1233: default:
1234: error("Error checking host key %s %s in "
1235: "revoked keys file %s: %s", sshkey_type(host_key),
1236: fp, options.revoked_host_keys, ssh_err(r));
1237: r = -1;
1238: goto out;
1239: }
1.250 djm 1240: }
1241:
1.247 djm 1242: if (options.verify_host_key_dns) {
1243: /*
1244: * XXX certs are not yet supported for DNS, so downgrade
1245: * them and try the plain key.
1246: */
1.252 djm 1247: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1248: goto out;
1249: if (sshkey_is_cert(plain))
1250: sshkey_drop_cert(plain);
1.247 djm 1251: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1252: if (flags & DNS_VERIFY_FOUND) {
1253: if (options.verify_host_key_dns == 1 &&
1254: flags & DNS_VERIFY_MATCH &&
1255: flags & DNS_VERIFY_SECURE) {
1.250 djm 1256: r = 0;
1.252 djm 1257: goto out;
1.247 djm 1258: }
1259: if (flags & DNS_VERIFY_MATCH) {
1260: matching_host_key_dns = 1;
1261: } else {
1262: warn_changed_key(plain);
1263: error("Update the SSHFP RR in DNS "
1264: "with the new host key to get rid "
1265: "of this message.");
1266: }
1.153 jakob 1267: }
1.140 jakob 1268: }
1269: }
1.250 djm 1270: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1271: options.user_hostfiles, options.num_user_hostfiles,
1272: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1273:
1.252 djm 1274: out:
1275: sshkey_free(plain);
1276: free(fp);
1.267 djm 1277: free(cafp);
1.250 djm 1278: if (r == 0 && host_key != NULL) {
1279: key_free(previous_host_key);
1280: previous_host_key = key_from_private(host_key);
1281: }
1282:
1283: return r;
1.51 markus 1284: }
1.70 markus 1285:
1.51 markus 1286: /*
1287: * Starts a dialog with the server, and authenticates the current user on the
1288: * server. This does not need any extra privileges. The basic connection
1289: * to the server must already have been established before this is called.
1290: * If login fails, this function prints an error and never returns.
1291: * This function does not require super-user privileges.
1292: */
1293: void
1.120 markus 1294: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1295: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1296: {
1.241 djm 1297: char *host;
1.70 markus 1298: char *server_user, *local_user;
1299:
1300: local_user = xstrdup(pw->pw_name);
1301: server_user = options.user ? options.user : local_user;
1.51 markus 1302:
1303: /* Convert the user-supplied hostname into all lowercase. */
1304: host = xstrdup(orighost);
1.241 djm 1305: lowercase(host);
1.51 markus 1306:
1307: /* Exchange protocol version identification strings with the server. */
1.202 djm 1308: ssh_exchange_identification(timeout_ms);
1.51 markus 1309:
1310: /* Put the connection into non-blocking mode. */
1311: packet_set_nonblocking();
1312:
1313: /* key exchange */
1314: /* authenticate user */
1.261 dtucker 1315: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.276 ! djm 1316: ssh_kex2(host, hostaddr, port);
! 1317: ssh_userauth2(local_user, server_user, host, sensitive);
1.238 djm 1318: free(local_user);
1.97 markus 1319: }
1320:
1321: void
1322: ssh_put_password(char *password)
1323: {
1324: int size;
1325: char *padded;
1326:
1.99 deraadt 1327: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1328: packet_put_cstring(password);
1.99 deraadt 1329: return;
1330: }
1.272 deraadt 1331: size = ROUNDUP(strlen(password) + 1, 32);
1.179 djm 1332: padded = xcalloc(1, size);
1.97 markus 1333: strlcpy(padded, password, size);
1334: packet_put_string(padded, size);
1.245 djm 1335: explicit_bzero(padded, size);
1.238 djm 1336: free(padded);
1.132 markus 1337: }
1338:
1339: /* print all known host keys for a given host, but skip keys of given type */
1340: static int
1.229 djm 1341: show_other_keys(struct hostkeys *hostkeys, Key *key)
1.132 markus 1342: {
1.242 djm 1343: int type[] = {
1344: KEY_RSA1,
1345: KEY_RSA,
1346: KEY_DSA,
1347: KEY_ECDSA,
1348: KEY_ED25519,
1349: -1
1350: };
1.229 djm 1351: int i, ret = 0;
1352: char *fp, *ra;
1353: const struct hostkey_entry *found;
1.132 markus 1354:
1355: for (i = 0; type[i] != -1; i++) {
1356: if (type[i] == key->type)
1357: continue;
1.229 djm 1358: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1359: continue;
1.259 djm 1360: fp = sshkey_fingerprint(found->key,
1.254 djm 1361: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1362: ra = sshkey_fingerprint(found->key,
1.254 djm 1363: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1364: if (fp == NULL || ra == NULL)
1365: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1366: logit("WARNING: %s key found for host %s\n"
1367: "in %s:%lu\n"
1368: "%s key fingerprint %s.",
1369: key_type(found->key),
1370: found->host, found->file, found->line,
1371: key_type(found->key), fp);
1372: if (options.visual_host_key)
1373: logit("%s", ra);
1.238 djm 1374: free(ra);
1375: free(fp);
1.229 djm 1376: ret = 1;
1.132 markus 1377: }
1.229 djm 1378: return ret;
1.150 jakob 1379: }
1380:
1381: static void
1382: warn_changed_key(Key *host_key)
1383: {
1384: char *fp;
1385:
1.259 djm 1386: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1387: SSH_FP_DEFAULT);
1.259 djm 1388: if (fp == NULL)
1389: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1390:
1391: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1392: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1393: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1394: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1395: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1396: error("It is also possible that a host key has just been changed.");
1.150 jakob 1397: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.230 markus 1398: key_type(host_key), fp);
1.150 jakob 1399: error("Please contact your system administrator.");
1400:
1.238 djm 1401: free(fp);
1.171 reyk 1402: }
1403:
1404: /*
1405: * Execute a local command
1406: */
1407: int
1408: ssh_local_cmd(const char *args)
1409: {
1410: char *shell;
1411: pid_t pid;
1412: int status;
1.231 djm 1413: void (*osighand)(int);
1.171 reyk 1414:
1415: if (!options.permit_local_command ||
1416: args == NULL || !*args)
1417: return (1);
1418:
1.226 djm 1419: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1420: shell = _PATH_BSHELL;
1421:
1.231 djm 1422: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1423: pid = fork();
1424: if (pid == 0) {
1.232 djm 1425: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1426: debug3("Executing %s -c \"%s\"", shell, args);
1427: execl(shell, shell, "-c", args, (char *)NULL);
1428: error("Couldn't execute %s -c \"%s\": %s",
1429: shell, args, strerror(errno));
1430: _exit(1);
1431: } else if (pid == -1)
1432: fatal("fork failed: %.100s", strerror(errno));
1433: while (waitpid(pid, &status, 0) == -1)
1434: if (errno != EINTR)
1435: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1436: signal(SIGCHLD, osighand);
1.171 reyk 1437:
1438: if (!WIFEXITED(status))
1439: return (1);
1440:
1441: return (WEXITSTATUS(status));
1.266 jcs 1442: }
1443:
1444: void
1445: maybe_add_key_to_agent(char *authfile, Key *private, char *comment,
1446: char *passphrase)
1447: {
1448: int auth_sock = -1, r;
1449:
1450: if (options.add_keys_to_agent == 0)
1451: return;
1452:
1453: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1454: debug3("no authentication agent, not adding key");
1455: return;
1456: }
1457:
1458: if (options.add_keys_to_agent == 2 &&
1459: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1460: debug3("user denied adding this key");
1.273 dtucker 1461: close(auth_sock);
1.266 jcs 1462: return;
1463: }
1464:
1465: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1466: (options.add_keys_to_agent == 3))) == 0)
1467: debug("identity added to agent: %s", authfile);
1468: else
1469: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1470: close(auth_sock);
1.1 deraadt 1471: }
![[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