Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.291
1.291 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.290 2018/01/23 05:17:04 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;
1.290 djm 407: int oerrno, 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 &&
1.290 djm 427: ai->ai_family != AF_INET6) {
428: errno = EAFNOSUPPORT;
1.49 markus 429: continue;
1.290 djm 430: }
1.49 markus 431: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
432: ntop, sizeof(ntop), strport, sizeof(strport),
433: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.290 djm 434: oerrno = errno;
1.265 djm 435: error("%s: getnameinfo failed", __func__);
1.290 djm 436: errno = oerrno;
1.49 markus 437: continue;
438: }
439: debug("Connecting to %.200s [%.100s] port %s.",
440: host, ntop, strport);
441:
442: /* Create a socket for connecting. */
1.139 markus 443: sock = ssh_create_socket(needpriv, ai);
1.49 markus 444: if (sock < 0)
1.110 markus 445: /* Any error is already output */
1.290 djm 446: errno = 0;
1.49 markus 447: continue;
448:
1.141 djm 449: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 450: timeout_ms) >= 0) {
1.49 markus 451: /* Successful connection. */
1.102 markus 452: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 453: break;
1.49 markus 454: } else {
1.290 djm 455: oerrno = errno;
1.131 itojun 456: debug("connect to address %s port %s: %s",
457: ntop, strport, strerror(errno));
1.38 markus 458: close(sock);
1.181 markus 459: sock = -1;
1.290 djm 460: errno = oerrno;
1.38 markus 461: }
462: }
1.181 markus 463: if (sock != -1)
1.49 markus 464: break; /* Successful connection. */
1.38 markus 465: }
1.49 markus 466:
1.38 markus 467: /* Return failure if we didn't get a successful connection. */
1.181 markus 468: if (sock == -1) {
1.159 markus 469: error("ssh: connect to host %s port %s: %s",
1.290 djm 470: host, strport, errno == 0 ? "failure" : strerror(errno));
471: return -1;
1.130 itojun 472: }
1.38 markus 473:
474: debug("Connection established.");
1.90 markus 475:
1.155 markus 476: /* Set SO_KEEPALIVE if requested. */
1.202 djm 477: if (want_keepalive &&
1.90 markus 478: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
479: sizeof(on)) < 0)
480: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 481:
482: /* Set the connection. */
1.286 djm 483: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
484: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 485:
1.286 djm 486: return 0;
1.59 markus 487: }
488:
1.241 djm 489: int
1.286 djm 490: ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs,
1.241 djm 491: struct sockaddr_storage *hostaddr, u_short port, int family,
492: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
493: {
494: if (options.proxy_command == NULL) {
1.286 djm 495: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
496: family, connection_attempts, timeout_ms, want_keepalive,
497: needpriv);
1.241 djm 498: } else if (strcmp(options.proxy_command, "-") == 0) {
1.286 djm 499: if ((ssh_packet_set_connection(ssh,
500: STDIN_FILENO, STDOUT_FILENO)) == NULL)
501: return -1; /* ssh_packet_set_connection logs error */
502: return 0;
1.241 djm 503: } else if (options.proxy_use_fdpass) {
1.286 djm 504: return ssh_proxy_fdpass_connect(ssh, host, port,
1.241 djm 505: options.proxy_command);
506: }
1.286 djm 507: return ssh_proxy_connect(ssh, host, port, options.proxy_command);
1.241 djm 508: }
509:
1.235 djm 510: static void
511: send_client_banner(int connection_out, int minor1)
512: {
513: /* Send our own protocol version identification. */
1.276 djm 514: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
515: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
1.270 markus 516: if (atomicio(vwrite, connection_out, client_version_string,
1.235 djm 517: strlen(client_version_string)) != strlen(client_version_string))
518: fatal("write: %.100s", strerror(errno));
519: chop(client_version_string);
520: debug("Local version string %.100s", client_version_string);
521: }
522:
1.43 markus 523: /*
1.39 deraadt 524: * Waits for the server identification string, and sends our own
525: * identification string.
526: */
1.213 andreas 527: void
1.202 djm 528: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 529: {
1.38 markus 530: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 531: int remote_major, remote_minor, mismatch;
1.38 markus 532: int connection_in = packet_get_connection_in();
533: int connection_out = packet_get_connection_out();
1.185 djm 534: u_int i, n;
1.202 djm 535: size_t len;
1.282 djm 536: int rc;
1.38 markus 537:
1.275 djm 538: send_client_banner(connection_out, 0);
1.235 djm 539:
1.163 avsm 540: /* Read other side's version identification. */
1.185 djm 541: for (n = 0;;) {
1.75 markus 542: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 543: if (timeout_ms > 0) {
1.282 djm 544: rc = waitrfd(connection_in, &timeout_ms);
545: if (rc == -1 && errno == ETIMEDOUT) {
1.202 djm 546: fatal("Connection timed out during "
547: "banner exchange");
1.282 djm 548: } else if (rc == -1) {
549: fatal("%s: %s",
550: __func__, strerror(errno));
1.202 djm 551: }
552: }
553:
1.270 markus 554: len = atomicio(read, connection_in, &buf[i], 1);
1.167 djm 555: if (len != 1 && errno == EPIPE)
1.202 djm 556: fatal("ssh_exchange_identification: "
557: "Connection closed by remote host");
1.163 avsm 558: else if (len != 1)
1.202 djm 559: fatal("ssh_exchange_identification: "
560: "read: %.100s", strerror(errno));
1.75 markus 561: if (buf[i] == '\r') {
562: buf[i] = '\n';
563: buf[i + 1] = 0;
564: continue; /**XXX wait for \n */
565: }
566: if (buf[i] == '\n') {
567: buf[i + 1] = 0;
568: break;
569: }
1.185 djm 570: if (++n > 65536)
1.202 djm 571: fatal("ssh_exchange_identification: "
572: "No banner received");
1.38 markus 573: }
1.75 markus 574: buf[sizeof(buf) - 1] = 0;
1.76 markus 575: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 576: break;
1.75 markus 577: debug("ssh_exchange_identification: %s", buf);
1.38 markus 578: }
1.59 markus 579: server_version_string = xstrdup(buf);
1.38 markus 580:
1.40 markus 581: /*
582: * Check that the versions match. In future this might accept
583: * several versions and set appropriate flags to handle them.
584: */
1.59 markus 585: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
586: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 587: fatal("Bad remote protocol version identification: '%.100s'", buf);
588: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 589: remote_major, remote_minor, remote_version);
1.38 markus 590:
1.255 markus 591: active_state->compat = compat_datafellows(remote_version);
1.64 markus 592: mismatch = 0;
1.59 markus 593:
1.116 deraadt 594: switch (remote_major) {
1.276 djm 595: case 2:
596: break;
1.64 markus 597: case 1:
1.276 djm 598: if (remote_minor != 99)
1.64 markus 599: mismatch = 1;
600: break;
1.68 markus 601: default:
1.64 markus 602: mismatch = 1;
603: break;
1.38 markus 604: }
1.64 markus 605: if (mismatch)
1.38 markus 606: fatal("Protocol major versions differ: %d vs. %d",
1.275 djm 607: PROTOCOL_MAJOR_2, remote_major);
1.243 djm 608: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
609: logit("Server version \"%.100s\" uses unsafe RSA signature "
610: "scheme; disabling use of RSA keys", remote_version);
1.59 markus 611: chop(server_version_string);
1.1 deraadt 612: }
613:
1.96 markus 614: /* defaults to 'no' */
1.109 itojun 615: static int
1.112 markus 616: confirm(const char *prompt)
1.1 deraadt 617: {
1.119 markus 618: const char *msg, *again = "Please type 'yes' or 'no': ";
619: char *p;
620: int ret = -1;
1.96 markus 621:
622: if (options.batch_mode)
623: return 0;
1.119 markus 624: for (msg = prompt;;msg = again) {
625: p = read_passphrase(msg, RP_ECHO);
1.289 djm 626: if (p == NULL)
627: return 0;
628: p[strcspn(p, "\n")] = '\0';
629: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 630: ret = 0;
1.289 djm 631: else if (strcasecmp(p, "yes") == 0)
1.119 markus 632: ret = 1;
1.238 djm 633: free(p);
1.119 markus 634: if (ret != -1)
635: return ret;
1.1 deraadt 636: }
637: }
638:
1.219 djm 639: static int
1.279 markus 640: check_host_cert(const char *host, const struct sshkey *host_key)
1.219 djm 641: {
642: const char *reason;
643:
644: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
645: error("%s", reason);
646: return 0;
647: }
1.249 djm 648: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 649: error("Certificate for %s contains unsupported "
650: "critical options(s)", host);
1.219 djm 651: return 0;
652: }
653: return 1;
654: }
655:
1.229 djm 656: static int
657: sockaddr_is_local(struct sockaddr *hostaddr)
658: {
659: switch (hostaddr->sa_family) {
660: case AF_INET:
661: return (ntohl(((struct sockaddr_in *)hostaddr)->
662: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
663: case AF_INET6:
664: return IN6_IS_ADDR_LOOPBACK(
665: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
666: default:
667: return 0;
668: }
669: }
670:
671: /*
672: * Prepare the hostname and ip address strings that are used to lookup
673: * host keys in known_hosts files. These may have a port number appended.
674: */
675: void
676: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
677: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
678: {
679: char ntop[NI_MAXHOST];
680:
681: /*
682: * We don't have the remote ip-address for connections
683: * using a proxy command
684: */
685: if (hostfile_ipaddr != NULL) {
686: if (options.proxy_command == NULL) {
687: if (getnameinfo(hostaddr, hostaddr->sa_len,
688: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 689: fatal("%s: getnameinfo failed", __func__);
1.229 djm 690: *hostfile_ipaddr = put_host_port(ntop, port);
691: } else {
692: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
693: "command>");
694: }
695: }
696:
697: /*
698: * Allow the user to record the key under a different name or
699: * differentiate a non-standard port. This is useful for ssh
700: * tunneling over forwarded connections or if you run multiple
701: * sshd's on different ports on the same machine.
702: */
703: if (hostfile_hostname != NULL) {
704: if (options.host_key_alias != NULL) {
705: *hostfile_hostname = xstrdup(options.host_key_alias);
706: debug("using hostkeyalias: %s", *hostfile_hostname);
707: } else {
708: *hostfile_hostname = put_host_port(hostname, port);
709: }
710: }
711: }
712:
1.39 deraadt 713: /*
1.108 markus 714: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 715: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 716: */
1.197 dtucker 717: #define RDRW 0
718: #define RDONLY 1
719: #define ROQUIET 2
1.109 itojun 720: static int
1.197 dtucker 721: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 722: struct sshkey *host_key, int readonly,
1.234 djm 723: char **user_hostfiles, u_int num_user_hostfiles,
724: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 725: {
1.234 djm 726: HostStatus host_status;
727: HostStatus ip_status;
1.279 markus 728: struct sshkey *raw_key = NULL;
1.189 dtucker 729: char *ip = NULL, *host = NULL;
1.204 grunk 730: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 731: char msg[1024];
1.234 djm 732: const char *type;
733: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 734: int len, cancelled_forwarding = 0;
1.234 djm 735: int local = sockaddr_is_local(hostaddr);
1.280 markus 736: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 737: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 738: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 739: u_int i;
1.49 markus 740:
741: /*
742: * Force accepting of the host key for loopback/localhost. The
743: * problem is that if the home directory is NFS-mounted to multiple
744: * machines, localhost will refer to a different machine in each of
745: * them, and the user will get bogus HOST_CHANGED warnings. This
746: * essentially disables host authentication for localhost; however,
747: * this is probably not a real problem.
748: */
1.111 markus 749: if (options.no_host_authentication_for_localhost == 1 && local &&
750: options.host_key_alias == NULL) {
1.88 markus 751: debug("Forcing accepting of host key for "
752: "loopback/localhost.");
1.108 markus 753: return 0;
1.49 markus 754: }
1.42 markus 755:
756: /*
1.229 djm 757: * Prepare the hostname and address strings used for hostkey lookup.
758: * In some cases, these will have a port number appended.
1.42 markus 759: */
1.229 djm 760: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 761:
762: /*
1.88 markus 763: * Turn off check_host_ip if the connection is to localhost, via proxy
764: * command or if we don't have a hostname to compare with
765: */
1.189 dtucker 766: if (options.check_host_ip && (local ||
767: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 768: options.check_host_ip = 0;
1.86 markus 769:
1.229 djm 770: host_hostkeys = init_hostkeys();
1.234 djm 771: for (i = 0; i < num_user_hostfiles; i++)
772: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
773: for (i = 0; i < num_system_hostfiles; i++)
774: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 775:
776: ip_hostkeys = NULL;
777: if (!want_cert && options.check_host_ip) {
778: ip_hostkeys = init_hostkeys();
1.234 djm 779: for (i = 0; i < num_user_hostfiles; i++)
780: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
781: for (i = 0; i < num_system_hostfiles; i++)
782: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 783: }
1.38 markus 784:
1.219 djm 785: retry:
1.229 djm 786: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 787: want_cert = sshkey_is_cert(host_key);
788: type = sshkey_type(host_key);
1.219 djm 789:
1.46 markus 790: /*
1.170 djm 791: * Check if the host key is present in the user's list of known
1.40 markus 792: * hosts or in the systemwide list.
793: */
1.229 djm 794: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
795: &host_found);
796:
1.40 markus 797: /*
798: * Also perform check for the ip address, skip the check if we are
1.219 djm 799: * localhost, looking for a certificate, or the hostname was an ip
800: * address to begin with.
1.40 markus 801: */
1.229 djm 802: if (!want_cert && ip_hostkeys != NULL) {
803: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
804: &ip_found);
1.38 markus 805: if (host_status == HOST_CHANGED &&
1.229 djm 806: (ip_status != HOST_CHANGED ||
807: (ip_found != NULL &&
1.280 markus 808: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 809: host_ip_differ = 1;
810: } else
811: ip_status = host_status;
812:
813: switch (host_status) {
814: case HOST_OK:
815: /* The host is known and the key matches. */
1.219 djm 816: debug("Host '%.200s' is known and matches the %s host %s.",
817: host, type, want_cert ? "certificate" : "key");
1.229 djm 818: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
819: host_found->file, host_found->line);
1.281 djm 820: if (want_cert &&
821: !check_host_cert(options.host_key_alias == NULL ?
822: hostname : options.host_key_alias, host_key))
1.219 djm 823: goto fail;
1.88 markus 824: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 825: if (readonly || want_cert)
1.138 itojun 826: logit("%s host key for IP address "
1.108 markus 827: "'%.128s' not in list of known hosts.",
828: type, ip);
1.234 djm 829: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 830: host_key, options.hash_known_hosts))
1.138 itojun 831: logit("Failed to add the %s host key for IP "
1.108 markus 832: "address '%.128s' to the list of known "
1.262 dtucker 833: "hosts (%.500s).", type, ip,
1.234 djm 834: user_hostfiles[0]);
1.88 markus 835: else
1.138 itojun 836: logit("Warning: Permanently added the %s host "
1.108 markus 837: "key for IP address '%.128s' to the list "
838: "of known hosts.", type, ip);
1.209 grunk 839: } else if (options.visual_host_key) {
1.259 djm 840: fp = sshkey_fingerprint(host_key,
1.254 djm 841: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 842: ra = sshkey_fingerprint(host_key,
1.254 djm 843: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 844: if (fp == NULL || ra == NULL)
845: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 846: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 847: free(ra);
848: free(fp);
1.38 markus 849: }
1.257 djm 850: hostkey_trusted = 1;
1.38 markus 851: break;
852: case HOST_NEW:
1.197 dtucker 853: if (options.host_key_alias == NULL && port != 0 &&
854: port != SSH_DEFAULT_PORT) {
855: debug("checking without port identifier");
1.212 stevesk 856: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 857: ROQUIET, user_hostfiles, num_user_hostfiles,
858: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 859: debug("found matching key w/out port");
860: break;
861: }
862: }
1.219 djm 863: if (readonly || want_cert)
1.108 markus 864: goto fail;
1.38 markus 865: /* The host is new. */
1.285 djm 866: if (options.strict_host_key_checking ==
867: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 868: /*
869: * User has requested strict host key checking. We
870: * will not add the host key automatically. The only
871: * alternative left is to abort.
872: */
873: error("No %s host key is known for %.200s and you "
874: "have requested strict checking.", type, host);
875: goto fail;
1.285 djm 876: } else if (options.strict_host_key_checking ==
877: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 878: char msg1[1024], msg2[1024];
879:
1.229 djm 880: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 881: snprintf(msg1, sizeof(msg1),
1.168 djm 882: "\nbut keys of different type are already"
883: " known for this host.");
1.145 jakob 884: else
885: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 886: /* The default */
1.259 djm 887: fp = sshkey_fingerprint(host_key,
1.254 djm 888: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 889: ra = sshkey_fingerprint(host_key,
1.254 djm 890: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 891: if (fp == NULL || ra == NULL)
892: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 893: msg2[0] = '\0';
894: if (options.verify_host_key_dns) {
1.153 jakob 895: if (matching_host_key_dns)
1.145 jakob 896: snprintf(msg2, sizeof(msg2),
897: "Matching host key fingerprint"
898: " found in DNS.\n");
899: else
900: snprintf(msg2, sizeof(msg2),
901: "No matching host key fingerprint"
902: " found in DNS.\n");
903: }
1.119 markus 904: snprintf(msg, sizeof(msg),
1.108 markus 905: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 906: "established%s\n"
1.209 grunk 907: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 908: "Are you sure you want to continue connecting "
1.132 markus 909: "(yes/no)? ",
1.209 grunk 910: host, ip, msg1, type, fp,
911: options.visual_host_key ? "\n" : "",
912: options.visual_host_key ? ra : "",
913: msg2);
1.238 djm 914: free(ra);
915: free(fp);
1.119 markus 916: if (!confirm(msg))
1.108 markus 917: goto fail;
1.257 djm 918: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 919: }
1.161 djm 920: /*
1.285 djm 921: * If in "new" or "off" strict mode, add the key automatically
922: * to the local known_hosts file.
1.161 djm 923: */
1.88 markus 924: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 925: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 926: hostp = hostline;
1.161 djm 927: if (options.hash_known_hosts) {
928: /* Add hash of host and IP separately */
1.234 djm 929: r = add_host_to_hostfile(user_hostfiles[0],
930: host, host_key, options.hash_known_hosts) &&
931: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 932: host_key, options.hash_known_hosts);
933: } else {
934: /* Add unhashed "host,ip" */
1.234 djm 935: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 936: hostline, host_key,
937: options.hash_known_hosts);
938: }
939: } else {
1.234 djm 940: r = add_host_to_hostfile(user_hostfiles[0], host,
941: host_key, options.hash_known_hosts);
1.38 markus 942: hostp = host;
1.161 djm 943: }
1.38 markus 944:
1.161 djm 945: if (!r)
1.138 itojun 946: logit("Failed to add the host to the list of known "
1.234 djm 947: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 948: else
1.138 itojun 949: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 950: "list of known hosts.", hostp, type);
1.38 markus 951: break;
1.220 djm 952: case HOST_REVOKED:
953: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
954: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
955: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
956: error("The %s host key for %s is marked as revoked.", type, host);
957: error("This could mean that a stolen key is being used to");
958: error("impersonate this host.");
959:
960: /*
961: * If strict host key checking is in use, the user will have
962: * to edit the key manually and we can only abort.
963: */
1.285 djm 964: if (options.strict_host_key_checking !=
965: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 966: error("%s host key for %.200s was revoked and you have "
967: "requested strict checking.", type, host);
968: goto fail;
969: }
970: goto continue_unsafe;
971:
1.38 markus 972: case HOST_CHANGED:
1.219 djm 973: if (want_cert) {
974: /*
975: * This is only a debug() since it is valid to have
976: * CAs with wildcard DNS matches that don't match
977: * all hosts that one might visit.
978: */
979: debug("Host certificate authority does not "
1.229 djm 980: "match %s in %s:%lu", CA_MARKER,
981: host_found->file, host_found->line);
1.219 djm 982: goto fail;
983: }
1.197 dtucker 984: if (readonly == ROQUIET)
985: goto fail;
1.38 markus 986: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 987: char *key_msg;
1.38 markus 988: if (ip_status == HOST_NEW)
1.158 avsm 989: key_msg = "is unknown";
1.38 markus 990: else if (ip_status == HOST_OK)
1.158 avsm 991: key_msg = "is unchanged";
1.38 markus 992: else
1.158 avsm 993: key_msg = "has a different value";
1.38 markus 994: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
995: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
996: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 997: error("The %s host key for %s has changed,", type, host);
1.208 ian 998: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 999: error("%s. This could either mean that", key_msg);
1.38 markus 1000: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 1001: error("and its host key have changed at the same time.");
1.88 markus 1002: if (ip_status != HOST_NEW)
1.229 djm 1003: error("Offending key for IP in %s:%lu",
1004: ip_found->file, ip_found->line);
1.38 markus 1005: }
1006: /* The host key has changed. */
1.150 jakob 1007: warn_changed_key(host_key);
1.38 markus 1008: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1009: user_hostfiles[0]);
1.280 markus 1010: error("Offending %s key in %s:%lu",
1011: sshkey_type(host_found->key),
1.229 djm 1012: host_found->file, host_found->line);
1.38 markus 1013:
1.40 markus 1014: /*
1015: * If strict host key checking is in use, the user will have
1016: * to edit the key manually and we can only abort.
1017: */
1.285 djm 1018: if (options.strict_host_key_checking !=
1019: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 1020: error("%s host key for %.200s has changed and you have "
1021: "requested strict checking.", type, host);
1022: goto fail;
1023: }
1.38 markus 1024:
1.220 djm 1025: continue_unsafe:
1.40 markus 1026: /*
1027: * If strict host key checking has not been requested, allow
1.144 djm 1028: * the connection but without MITM-able authentication or
1.194 stevesk 1029: * forwarding.
1.40 markus 1030: */
1.38 markus 1031: if (options.password_authentication) {
1.108 markus 1032: error("Password authentication is disabled to avoid "
1033: "man-in-the-middle attacks.");
1.38 markus 1034: options.password_authentication = 0;
1.210 dtucker 1035: cancelled_forwarding = 1;
1.144 djm 1036: }
1037: if (options.kbd_interactive_authentication) {
1038: error("Keyboard-interactive authentication is disabled"
1039: " to avoid man-in-the-middle attacks.");
1040: options.kbd_interactive_authentication = 0;
1041: options.challenge_response_authentication = 0;
1.210 dtucker 1042: cancelled_forwarding = 1;
1.144 djm 1043: }
1044: if (options.challenge_response_authentication) {
1045: error("Challenge/response authentication is disabled"
1046: " to avoid man-in-the-middle attacks.");
1047: options.challenge_response_authentication = 0;
1.210 dtucker 1048: cancelled_forwarding = 1;
1.38 markus 1049: }
1050: if (options.forward_agent) {
1.108 markus 1051: error("Agent forwarding is disabled to avoid "
1052: "man-in-the-middle attacks.");
1.38 markus 1053: options.forward_agent = 0;
1.210 dtucker 1054: cancelled_forwarding = 1;
1.83 markus 1055: }
1056: if (options.forward_x11) {
1.108 markus 1057: error("X11 forwarding is disabled to avoid "
1058: "man-in-the-middle attacks.");
1.83 markus 1059: options.forward_x11 = 0;
1.210 dtucker 1060: cancelled_forwarding = 1;
1.83 markus 1061: }
1.108 markus 1062: if (options.num_local_forwards > 0 ||
1063: options.num_remote_forwards > 0) {
1064: error("Port forwarding is disabled to avoid "
1065: "man-in-the-middle attacks.");
1066: options.num_local_forwards =
1.118 deraadt 1067: options.num_remote_forwards = 0;
1.210 dtucker 1068: cancelled_forwarding = 1;
1.194 stevesk 1069: }
1070: if (options.tun_open != SSH_TUNMODE_NO) {
1071: error("Tunnel forwarding is disabled to avoid "
1072: "man-in-the-middle attacks.");
1073: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1074: cancelled_forwarding = 1;
1.38 markus 1075: }
1.210 dtucker 1076: if (options.exit_on_forward_failure && cancelled_forwarding)
1077: fatal("Error: forwarding disabled due to host key "
1078: "check failure");
1079:
1.40 markus 1080: /*
1081: * XXX Should permit the user to change to use the new id.
1082: * This could be done by converting the host key to an
1083: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1084: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1085: * accept the authentication.
1086: */
1.38 markus 1087: break;
1.132 markus 1088: case HOST_FOUND:
1089: fatal("internal error");
1090: break;
1.88 markus 1091: }
1092:
1093: if (options.check_host_ip && host_status != HOST_CHANGED &&
1094: ip_status == HOST_CHANGED) {
1.119 markus 1095: snprintf(msg, sizeof(msg),
1096: "Warning: the %s host key for '%.200s' "
1097: "differs from the key for the IP address '%.128s'"
1.229 djm 1098: "\nOffending key for IP in %s:%lu",
1099: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1100: if (host_status == HOST_OK) {
1101: len = strlen(msg);
1102: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1103: "\nMatching host key in %s:%lu",
1104: host_found->file, host_found->line);
1.119 markus 1105: }
1.285 djm 1106: if (options.strict_host_key_checking ==
1107: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1108: strlcat(msg, "\nAre you sure you want "
1109: "to continue connecting (yes/no)? ", sizeof(msg));
1110: if (!confirm(msg))
1.108 markus 1111: goto fail;
1.285 djm 1112: } else if (options.strict_host_key_checking !=
1113: SSH_STRICT_HOSTKEY_OFF) {
1114: logit("%s", msg);
1115: error("Exiting, you have requested strict checking.");
1116: goto fail;
1.119 markus 1117: } else {
1.143 djm 1118: logit("%s", msg);
1.88 markus 1119: }
1.257 djm 1120: }
1121:
1122: if (!hostkey_trusted && options.update_hostkeys) {
1123: debug("%s: hostkey not known or explicitly trusted: "
1124: "disabling UpdateHostkeys", __func__);
1125: options.update_hostkeys = 0;
1.38 markus 1126: }
1.82 provos 1127:
1.238 djm 1128: free(ip);
1129: free(host);
1.229 djm 1130: if (host_hostkeys != NULL)
1131: free_hostkeys(host_hostkeys);
1132: if (ip_hostkeys != NULL)
1133: free_hostkeys(ip_hostkeys);
1.108 markus 1134: return 0;
1135:
1136: fail:
1.220 djm 1137: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1138: /*
1139: * No matching certificate. Downgrade cert to raw key and
1140: * search normally.
1141: */
1142: debug("No matching CA found. Retry with plain key");
1.280 markus 1143: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1144: fatal("%s: sshkey_from_private: %s",
1145: __func__, ssh_err(r));
1146: if ((r = sshkey_drop_cert(raw_key)) != 0)
1147: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1148: host_key = raw_key;
1149: goto retry;
1150: }
1151: if (raw_key != NULL)
1.280 markus 1152: sshkey_free(raw_key);
1.238 djm 1153: free(ip);
1154: free(host);
1.229 djm 1155: if (host_hostkeys != NULL)
1156: free_hostkeys(host_hostkeys);
1157: if (ip_hostkeys != NULL)
1158: free_hostkeys(ip_hostkeys);
1.108 markus 1159: return -1;
1160: }
1161:
1.140 jakob 1162: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1163: int
1.279 markus 1164: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1165: {
1.267 djm 1166: u_int i;
1.250 djm 1167: int r = -1, flags = 0;
1.267 djm 1168: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1169: struct sshkey *plain = NULL;
1.229 djm 1170:
1.252 djm 1171: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1172: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1173: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1174: r = -1;
1175: goto out;
1176: }
1177:
1.267 djm 1178: if (sshkey_is_cert(host_key)) {
1179: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1180: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1181: error("%s: fingerprint CA key: %s",
1182: __func__, ssh_err(r));
1183: r = -1;
1184: goto out;
1185: }
1186: sshkey_format_cert_validity(host_key->cert,
1187: valid, sizeof(valid));
1188: debug("Server host certificate: %s %s, serial %llu "
1189: "ID \"%s\" CA %s %s valid %s",
1190: sshkey_ssh_name(host_key), fp,
1.269 djm 1191: (unsigned long long)host_key->cert->serial,
1192: host_key->cert->key_id,
1.267 djm 1193: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1194: valid);
1195: for (i = 0; i < host_key->cert->nprincipals; i++) {
1196: debug2("Server host certificate hostname: %s",
1197: host_key->cert->principals[i]);
1198: }
1199: } else {
1.276 djm 1200: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1201: }
1.252 djm 1202:
1203: if (sshkey_equal(previous_host_key, host_key)) {
1204: debug2("%s: server host key %s %s matches cached key",
1205: __func__, sshkey_type(host_key), fp);
1206: r = 0;
1207: goto out;
1208: }
1209:
1210: /* Check in RevokedHostKeys file if specified */
1211: if (options.revoked_host_keys != NULL) {
1212: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1213: switch (r) {
1214: case 0:
1215: break; /* not revoked */
1216: case SSH_ERR_KEY_REVOKED:
1217: error("Host key %s %s revoked by file %s",
1218: sshkey_type(host_key), fp,
1219: options.revoked_host_keys);
1220: r = -1;
1221: goto out;
1222: default:
1223: error("Error checking host key %s %s in "
1224: "revoked keys file %s: %s", sshkey_type(host_key),
1225: fp, options.revoked_host_keys, ssh_err(r));
1226: r = -1;
1227: goto out;
1228: }
1.250 djm 1229: }
1230:
1.247 djm 1231: if (options.verify_host_key_dns) {
1232: /*
1233: * XXX certs are not yet supported for DNS, so downgrade
1234: * them and try the plain key.
1235: */
1.252 djm 1236: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1237: goto out;
1238: if (sshkey_is_cert(plain))
1239: sshkey_drop_cert(plain);
1.247 djm 1240: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1241: if (flags & DNS_VERIFY_FOUND) {
1242: if (options.verify_host_key_dns == 1 &&
1243: flags & DNS_VERIFY_MATCH &&
1244: flags & DNS_VERIFY_SECURE) {
1.250 djm 1245: r = 0;
1.252 djm 1246: goto out;
1.247 djm 1247: }
1248: if (flags & DNS_VERIFY_MATCH) {
1249: matching_host_key_dns = 1;
1250: } else {
1.287 djm 1251: warn_changed_key(plain);
1252: error("Update the SSHFP RR in DNS "
1253: "with the new host key to get rid "
1254: "of this message.");
1.247 djm 1255: }
1.153 jakob 1256: }
1.140 jakob 1257: }
1258: }
1.250 djm 1259: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1260: options.user_hostfiles, options.num_user_hostfiles,
1261: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1262:
1.252 djm 1263: out:
1264: sshkey_free(plain);
1265: free(fp);
1.267 djm 1266: free(cafp);
1.250 djm 1267: if (r == 0 && host_key != NULL) {
1.280 markus 1268: sshkey_free(previous_host_key);
1269: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1270: }
1271:
1272: return r;
1.51 markus 1273: }
1.70 markus 1274:
1.51 markus 1275: /*
1276: * Starts a dialog with the server, and authenticates the current user on the
1277: * server. This does not need any extra privileges. The basic connection
1278: * to the server must already have been established before this is called.
1279: * If login fails, this function prints an error and never returns.
1280: * This function does not require super-user privileges.
1281: */
1282: void
1.120 markus 1283: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1284: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1285: {
1.241 djm 1286: char *host;
1.70 markus 1287: char *server_user, *local_user;
1288:
1289: local_user = xstrdup(pw->pw_name);
1290: server_user = options.user ? options.user : local_user;
1.51 markus 1291:
1292: /* Convert the user-supplied hostname into all lowercase. */
1293: host = xstrdup(orighost);
1.241 djm 1294: lowercase(host);
1.51 markus 1295:
1296: /* Exchange protocol version identification strings with the server. */
1.202 djm 1297: ssh_exchange_identification(timeout_ms);
1.51 markus 1298:
1299: /* Put the connection into non-blocking mode. */
1300: packet_set_nonblocking();
1301:
1302: /* key exchange */
1303: /* authenticate user */
1.261 dtucker 1304: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.276 djm 1305: ssh_kex2(host, hostaddr, port);
1306: ssh_userauth2(local_user, server_user, host, sensitive);
1.238 djm 1307: free(local_user);
1.97 markus 1308: }
1309:
1310: void
1311: ssh_put_password(char *password)
1312: {
1313: int size;
1314: char *padded;
1315:
1.99 deraadt 1316: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1317: packet_put_cstring(password);
1.99 deraadt 1318: return;
1319: }
1.272 deraadt 1320: size = ROUNDUP(strlen(password) + 1, 32);
1.179 djm 1321: padded = xcalloc(1, size);
1.97 markus 1322: strlcpy(padded, password, size);
1323: packet_put_string(padded, size);
1.245 djm 1324: explicit_bzero(padded, size);
1.238 djm 1325: free(padded);
1.132 markus 1326: }
1327:
1328: /* print all known host keys for a given host, but skip keys of given type */
1329: static int
1.279 markus 1330: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1331: {
1.242 djm 1332: int type[] = {
1333: KEY_RSA,
1334: KEY_DSA,
1335: KEY_ECDSA,
1336: KEY_ED25519,
1337: -1
1338: };
1.229 djm 1339: int i, ret = 0;
1340: char *fp, *ra;
1341: const struct hostkey_entry *found;
1.132 markus 1342:
1343: for (i = 0; type[i] != -1; i++) {
1344: if (type[i] == key->type)
1345: continue;
1.229 djm 1346: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1347: continue;
1.259 djm 1348: fp = sshkey_fingerprint(found->key,
1.254 djm 1349: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1350: ra = sshkey_fingerprint(found->key,
1.254 djm 1351: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1352: if (fp == NULL || ra == NULL)
1353: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1354: logit("WARNING: %s key found for host %s\n"
1355: "in %s:%lu\n"
1356: "%s key fingerprint %s.",
1357: key_type(found->key),
1358: found->host, found->file, found->line,
1359: key_type(found->key), fp);
1360: if (options.visual_host_key)
1361: logit("%s", ra);
1.238 djm 1362: free(ra);
1363: free(fp);
1.229 djm 1364: ret = 1;
1.132 markus 1365: }
1.229 djm 1366: return ret;
1.150 jakob 1367: }
1368:
1369: static void
1.279 markus 1370: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1371: {
1372: char *fp;
1373:
1.259 djm 1374: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1375: SSH_FP_DEFAULT);
1.259 djm 1376: if (fp == NULL)
1377: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1378:
1379: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1380: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1381: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1382: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1383: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1384: error("It is also possible that a host key has just been changed.");
1.150 jakob 1385: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.287 djm 1386: key_type(host_key), fp);
1.150 jakob 1387: error("Please contact your system administrator.");
1388:
1.238 djm 1389: free(fp);
1.171 reyk 1390: }
1391:
1392: /*
1393: * Execute a local command
1394: */
1395: int
1396: ssh_local_cmd(const char *args)
1397: {
1398: char *shell;
1399: pid_t pid;
1400: int status;
1.231 djm 1401: void (*osighand)(int);
1.171 reyk 1402:
1403: if (!options.permit_local_command ||
1404: args == NULL || !*args)
1405: return (1);
1406:
1.226 djm 1407: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1408: shell = _PATH_BSHELL;
1409:
1.231 djm 1410: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1411: pid = fork();
1412: if (pid == 0) {
1.232 djm 1413: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1414: debug3("Executing %s -c \"%s\"", shell, args);
1415: execl(shell, shell, "-c", args, (char *)NULL);
1416: error("Couldn't execute %s -c \"%s\": %s",
1417: shell, args, strerror(errno));
1418: _exit(1);
1419: } else if (pid == -1)
1420: fatal("fork failed: %.100s", strerror(errno));
1421: while (waitpid(pid, &status, 0) == -1)
1422: if (errno != EINTR)
1423: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1424: signal(SIGCHLD, osighand);
1.171 reyk 1425:
1426: if (!WIFEXITED(status))
1427: return (1);
1428:
1429: return (WEXITSTATUS(status));
1.266 jcs 1430: }
1431:
1432: void
1.279 markus 1433: maybe_add_key_to_agent(char *authfile, struct sshkey *private, char *comment,
1.266 jcs 1434: char *passphrase)
1435: {
1436: int auth_sock = -1, r;
1437:
1438: if (options.add_keys_to_agent == 0)
1439: return;
1440:
1441: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1442: debug3("no authentication agent, not adding key");
1443: return;
1444: }
1445:
1446: if (options.add_keys_to_agent == 2 &&
1447: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1448: debug3("user denied adding this key");
1.273 dtucker 1449: close(auth_sock);
1.266 jcs 1450: return;
1451: }
1452:
1453: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1454: (options.add_keys_to_agent == 3))) == 0)
1455: debug("identity added to agent: %s", authfile);
1456: else
1457: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1458: close(auth_sock);
1.1 deraadt 1459: }