Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.289
1.289 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.288 2017/11/25 06:46:22 dtucker Exp $ */
1.1 deraadt 2: /*
1.39 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
1.78 deraadt 8: *
9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 14: */
1.1 deraadt 15:
1.174 stevesk 16: #include <sys/types.h>
17: #include <sys/wait.h>
1.175 stevesk 18: #include <sys/stat.h>
1.187 stevesk 19: #include <sys/socket.h>
1.195 stevesk 20: #include <sys/time.h>
1.187 stevesk 21:
22: #include <netinet/in.h>
1.172 stevesk 23:
1.176 stevesk 24: #include <ctype.h>
1.190 stevesk 25: #include <errno.h>
1.216 dtucker 26: #include <fcntl.h>
1.191 stevesk 27: #include <netdb.h>
1.172 stevesk 28: #include <paths.h>
1.282 djm 29: #include <poll.h>
1.199 deraadt 30: #include <signal.h>
1.188 stevesk 31: #include <pwd.h>
1.198 stevesk 32: #include <stdio.h>
1.196 stevesk 33: #include <stdlib.h>
1.193 stevesk 34: #include <string.h>
1.192 stevesk 35: #include <unistd.h>
1.71 markus 36:
1.199 deraadt 37: #include "xmalloc.h"
1.91 markus 38: #include "ssh.h"
1.59 markus 39: #include "buffer.h"
1.1 deraadt 40: #include "packet.h"
41: #include "uidswap.h"
1.21 markus 42: #include "compat.h"
1.58 markus 43: #include "key.h"
1.71 markus 44: #include "sshconnect.h"
1.58 markus 45: #include "hostfile.h"
1.91 markus 46: #include "log.h"
1.251 millert 47: #include "misc.h"
1.91 markus 48: #include "readconf.h"
49: #include "atomicio.h"
1.140 jakob 50: #include "dns.h"
1.239 djm 51: #include "monitor_fdpass.h"
1.219 djm 52: #include "ssh2.h"
1.186 stevesk 53: #include "version.h"
1.252 djm 54: #include "authfile.h"
55: #include "ssherr.h"
1.266 jcs 56: #include "authfd.h"
1.140 jakob 57:
1.70 markus 58: char *client_version_string = NULL;
59: char *server_version_string = NULL;
1.279 markus 60: struct sshkey *previous_host_key = NULL;
1.59 markus 61:
1.169 stevesk 62: static int matching_host_key_dns = 0;
1.145 jakob 63:
1.227 djm 64: static pid_t proxy_command_pid = 0;
65:
1.124 markus 66: /* import */
1.43 markus 67: extern Options options;
1.50 markus 68: extern char *__progname;
1.124 markus 69: extern uid_t original_real_uid;
70: extern uid_t original_effective_uid;
1.91 markus 71:
1.279 markus 72: static int show_other_keys(struct hostkeys *, struct sshkey *);
73: static void warn_changed_key(struct sshkey *);
1.132 markus 74:
1.239 djm 75: /* Expand a proxy command */
76: static char *
77: expand_proxy_command(const char *proxy_command, const char *user,
78: const char *host, int port)
79: {
80: char *tmp, *ret, strport[NI_MAXSERV];
81:
1.241 djm 82: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 83: xasprintf(&tmp, "exec %s", proxy_command);
84: ret = percent_expand(tmp, "h", host, "p", strport,
85: "r", options.user, (char *)NULL);
86: free(tmp);
87: return ret;
88: }
89:
90: /*
91: * Connect to the given ssh server using a proxy command that passes a
92: * a connected fd back to us.
93: */
94: static int
1.286 djm 95: ssh_proxy_fdpass_connect(struct ssh *ssh, const char *host, u_short port,
1.239 djm 96: const char *proxy_command)
97: {
98: char *command_string;
99: int sp[2], sock;
100: pid_t pid;
101: char *shell;
102:
103: if ((shell = getenv("SHELL")) == NULL)
104: shell = _PATH_BSHELL;
105:
106: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
107: fatal("Could not create socketpair to communicate with "
108: "proxy dialer: %.100s", strerror(errno));
109:
110: command_string = expand_proxy_command(proxy_command, options.user,
111: host, port);
112: debug("Executing proxy dialer command: %.500s", command_string);
113:
114: /* Fork and execute the proxy command. */
115: if ((pid = fork()) == 0) {
116: char *argv[10];
117:
118: /* Child. Permanently give up superuser privileges. */
119: permanently_drop_suid(original_real_uid);
120:
121: close(sp[1]);
122: /* Redirect stdin and stdout. */
123: if (sp[0] != 0) {
124: if (dup2(sp[0], 0) < 0)
125: perror("dup2 stdin");
126: }
127: if (sp[0] != 1) {
128: if (dup2(sp[0], 1) < 0)
129: perror("dup2 stdout");
130: }
131: if (sp[0] >= 2)
132: close(sp[0]);
133:
134: /*
135: * Stderr is left as it is so that error messages get
136: * printed on the user's terminal.
137: */
138: argv[0] = shell;
139: argv[1] = "-c";
140: argv[2] = command_string;
141: argv[3] = NULL;
142:
143: /*
144: * Execute the proxy command.
145: * Note that we gave up any extra privileges above.
146: */
147: execv(argv[0], argv);
148: perror(argv[0]);
149: exit(1);
150: }
151: /* Parent. */
152: if (pid < 0)
153: fatal("fork failed: %.100s", strerror(errno));
154: close(sp[0]);
155: free(command_string);
156:
157: if ((sock = mm_receive_fd(sp[1])) == -1)
158: fatal("proxy dialer did not pass back a connection");
1.271 markus 159: close(sp[1]);
1.239 djm 160:
161: while (waitpid(pid, NULL, 0) == -1)
162: if (errno != EINTR)
163: fatal("Couldn't wait for child: %s", strerror(errno));
164:
165: /* Set the connection file descriptors. */
1.286 djm 166: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
167: return -1; /* ssh_packet_set_connection logs error */
1.239 djm 168:
169: return 0;
170: }
171:
1.39 deraadt 172: /*
173: * Connect to the given ssh server using a proxy command.
174: */
1.109 itojun 175: static int
1.286 djm 176: ssh_proxy_connect(struct ssh *ssh, const char *host, u_short port,
177: const char *proxy_command)
1.1 deraadt 178: {
1.239 djm 179: char *command_string;
1.38 markus 180: int pin[2], pout[2];
1.69 deraadt 181: pid_t pid;
1.239 djm 182: char *shell;
1.237 markus 183:
1.226 djm 184: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 185: shell = _PATH_BSHELL;
1.38 markus 186:
187: /* Create pipes for communicating with the proxy. */
188: if (pipe(pin) < 0 || pipe(pout) < 0)
189: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 190: strerror(errno));
1.38 markus 191:
1.239 djm 192: command_string = expand_proxy_command(proxy_command, options.user,
193: host, port);
1.38 markus 194: debug("Executing proxy command: %.500s", command_string);
195:
196: /* Fork and execute the proxy command. */
197: if ((pid = fork()) == 0) {
198: char *argv[10];
199:
200: /* Child. Permanently give up superuser privileges. */
1.184 markus 201: permanently_drop_suid(original_real_uid);
1.38 markus 202:
203: /* Redirect stdin and stdout. */
204: close(pin[1]);
205: if (pin[0] != 0) {
206: if (dup2(pin[0], 0) < 0)
207: perror("dup2 stdin");
208: close(pin[0]);
209: }
210: close(pout[0]);
211: if (dup2(pout[1], 1) < 0)
212: perror("dup2 stdout");
213: /* Cannot be 1 because pin allocated two descriptors. */
214: close(pout[1]);
215:
216: /* Stderr is left as it is so that error messages get
217: printed on the user's terminal. */
1.201 djm 218: argv[0] = shell;
1.38 markus 219: argv[1] = "-c";
220: argv[2] = command_string;
221: argv[3] = NULL;
222:
223: /* Execute the proxy command. Note that we gave up any
224: extra privileges above. */
1.232 djm 225: signal(SIGPIPE, SIG_DFL);
1.89 markus 226: execv(argv[0], argv);
227: perror(argv[0]);
1.38 markus 228: exit(1);
229: }
230: /* Parent. */
231: if (pid < 0)
232: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 233: else
234: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 235:
236: /* Close child side of the descriptors. */
237: close(pin[0]);
238: close(pout[1]);
239:
240: /* Free the command name. */
1.238 djm 241: free(command_string);
1.38 markus 242:
243: /* Set the connection file descriptors. */
1.286 djm 244: if (ssh_packet_set_connection(ssh, pout[0], pin[1]) == NULL)
245: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 246:
1.110 markus 247: return 0;
1.227 djm 248: }
249:
250: void
251: ssh_kill_proxy_command(void)
252: {
253: /*
254: * Send SIGHUP to proxy command if used. We don't wait() in
255: * case it hangs and instead rely on init to reap the child
256: */
257: if (proxy_command_pid > 1)
1.228 djm 258: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 259: }
260:
1.39 deraadt 261: /*
262: * Creates a (possibly privileged) socket for use as the ssh connection.
263: */
1.109 itojun 264: static int
1.139 markus 265: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 266: {
1.240 djm 267: int sock, r, gaierr;
1.246 djm 268: struct addrinfo hints, *res = NULL;
1.1 deraadt 269:
1.217 dtucker 270: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 271: if (sock < 0) {
1.240 djm 272: error("socket: %s", strerror(errno));
1.216 dtucker 273: return -1;
274: }
275: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 276:
277: /* Bind the socket to an alternative local IP address */
1.240 djm 278: if (options.bind_address == NULL && !privileged)
1.105 markus 279: return sock;
280:
1.246 djm 281: if (options.bind_address) {
282: memset(&hints, 0, sizeof(hints));
283: hints.ai_family = ai->ai_family;
284: hints.ai_socktype = ai->ai_socktype;
285: hints.ai_protocol = ai->ai_protocol;
286: hints.ai_flags = AI_PASSIVE;
287: gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
288: if (gaierr) {
289: error("getaddrinfo: %s: %s", options.bind_address,
290: ssh_gai_strerror(gaierr));
291: close(sock);
292: return -1;
293: }
1.105 markus 294: }
1.240 djm 295: /*
296: * If we are running as root and want to connect to a privileged
297: * port, bind our own socket to a privileged port.
298: */
299: if (privileged) {
300: PRIV_START;
1.246 djm 301: r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
1.240 djm 302: PRIV_END;
303: if (r < 0) {
304: error("bindresvport_sa: af=%d %s", ai->ai_family,
305: strerror(errno));
306: goto fail;
307: }
308: } else {
309: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
310: error("bind: %s: %s", options.bind_address,
311: strerror(errno));
312: fail:
313: close(sock);
314: freeaddrinfo(res);
315: return -1;
316: }
1.38 markus 317: }
1.246 djm 318: if (res != NULL)
319: freeaddrinfo(res);
1.38 markus 320: return sock;
1.1 deraadt 321: }
322:
1.282 djm 323: /*
324: * Wait up to *timeoutp milliseconds for fd to be readable. Updates
325: * *timeoutp with time remaining.
326: * Returns 0 if fd ready or -1 on timeout or error (see errno).
327: */
328: static int
329: waitrfd(int fd, int *timeoutp)
330: {
331: struct pollfd pfd;
332: struct timeval t_start;
333: int oerrno, r;
334:
1.288 dtucker 335: monotime_tv(&t_start);
1.282 djm 336: pfd.fd = fd;
337: pfd.events = POLLIN;
338: for (; *timeoutp >= 0;) {
339: r = poll(&pfd, 1, *timeoutp);
340: oerrno = errno;
341: ms_subtract_diff(&t_start, timeoutp);
342: errno = oerrno;
343: if (r > 0)
344: return 0;
345: else if (r == -1 && errno != EAGAIN)
346: return -1;
347: else if (r == 0)
348: break;
349: }
350: /* timeout */
351: errno = ETIMEDOUT;
352: return -1;
353: }
354:
1.141 djm 355: static int
356: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 357: socklen_t addrlen, int *timeoutp)
1.141 djm 358: {
1.282 djm 359: int optval = 0;
360: socklen_t optlen = sizeof(optval);
1.141 djm 361:
1.282 djm 362: /* No timeout: just do a blocking connect() */
363: if (*timeoutp <= 0)
364: return connect(sockfd, serv_addr, addrlen);
1.141 djm 365:
1.156 djm 366: set_nonblock(sockfd);
1.282 djm 367: if (connect(sockfd, serv_addr, addrlen) == 0) {
368: /* Succeeded already? */
1.156 djm 369: unset_nonblock(sockfd);
1.282 djm 370: return 0;
371: } else if (errno != EINPROGRESS)
372: return -1;
373:
374: if (waitrfd(sockfd, timeoutp) == -1)
375: return -1;
1.141 djm 376:
1.282 djm 377: /* Completed or failed */
378: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, &optlen) == -1) {
379: debug("getsockopt: %s", strerror(errno));
380: return -1;
1.141 djm 381: }
1.282 djm 382: if (optval != 0) {
383: errno = optval;
384: return -1;
1.202 djm 385: }
1.282 djm 386: unset_nonblock(sockfd);
387: return 0;
1.141 djm 388: }
389:
1.39 deraadt 390: /*
1.49 markus 391: * Opens a TCP/IP connection to the remote server on the given host.
392: * The address of the remote host will be returned in hostaddr.
1.124 markus 393: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 394: * a privileged port will be allocated to make the connection.
1.124 markus 395: * This requires super-user privileges if needpriv is true.
1.39 deraadt 396: * Connection_attempts specifies the maximum number of tries (one per
397: * second). If proxy_command is non-NULL, it specifies the command (with %h
398: * and %p substituted for host and port, respectively) to use to contact
399: * the daemon.
400: */
1.241 djm 401: static int
1.286 djm 402: ssh_connect_direct(struct ssh *ssh, const char *host, struct addrinfo *aitop,
1.241 djm 403: struct sockaddr_storage *hostaddr, u_short port, int family,
404: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
1.1 deraadt 405: {
1.90 markus 406: int on = 1;
1.49 markus 407: int sock = -1, attempt;
1.90 markus 408: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 409: struct addrinfo *ai;
1.38 markus 410:
1.265 djm 411: debug2("%s: needpriv %d", __func__, needpriv);
1.268 djm 412: memset(ntop, 0, sizeof(ntop));
413: memset(strport, 0, sizeof(strport));
1.38 markus 414:
1.181 markus 415: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 416: if (attempt > 0) {
417: /* Sleep a moment before retrying. */
418: sleep(1);
1.38 markus 419: debug("Trying again...");
1.200 markus 420: }
1.181 markus 421: /*
422: * Loop through addresses for this host, and try each one in
423: * sequence until the connection succeeds.
424: */
1.49 markus 425: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 426: if (ai->ai_family != AF_INET &&
427: ai->ai_family != AF_INET6)
1.49 markus 428: continue;
429: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
430: ntop, sizeof(ntop), strport, sizeof(strport),
431: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.265 djm 432: error("%s: getnameinfo failed", __func__);
1.49 markus 433: continue;
434: }
435: debug("Connecting to %.200s [%.100s] port %s.",
436: host, ntop, strport);
437:
438: /* Create a socket for connecting. */
1.139 markus 439: sock = ssh_create_socket(needpriv, ai);
1.49 markus 440: if (sock < 0)
1.110 markus 441: /* Any error is already output */
1.49 markus 442: continue;
443:
1.141 djm 444: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 445: timeout_ms) >= 0) {
1.49 markus 446: /* Successful connection. */
1.102 markus 447: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 448: break;
1.49 markus 449: } else {
1.131 itojun 450: debug("connect to address %s port %s: %s",
451: ntop, strport, strerror(errno));
1.38 markus 452: close(sock);
1.181 markus 453: sock = -1;
1.38 markus 454: }
455: }
1.181 markus 456: if (sock != -1)
1.49 markus 457: break; /* Successful connection. */
1.38 markus 458: }
1.49 markus 459:
1.38 markus 460: /* Return failure if we didn't get a successful connection. */
1.181 markus 461: if (sock == -1) {
1.159 markus 462: error("ssh: connect to host %s port %s: %s",
1.130 itojun 463: host, strport, strerror(errno));
1.159 markus 464: return (-1);
1.130 itojun 465: }
1.38 markus 466:
467: debug("Connection established.");
1.90 markus 468:
1.155 markus 469: /* Set SO_KEEPALIVE if requested. */
1.202 djm 470: if (want_keepalive &&
1.90 markus 471: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
472: sizeof(on)) < 0)
473: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 474:
475: /* Set the connection. */
1.286 djm 476: if (ssh_packet_set_connection(ssh, sock, sock) == NULL)
477: return -1; /* ssh_packet_set_connection logs error */
1.1 deraadt 478:
1.286 djm 479: return 0;
1.59 markus 480: }
481:
1.241 djm 482: int
1.286 djm 483: ssh_connect(struct ssh *ssh, const char *host, struct addrinfo *addrs,
1.241 djm 484: struct sockaddr_storage *hostaddr, u_short port, int family,
485: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
486: {
487: if (options.proxy_command == NULL) {
1.286 djm 488: return ssh_connect_direct(ssh, host, addrs, hostaddr, port,
489: family, connection_attempts, timeout_ms, want_keepalive,
490: needpriv);
1.241 djm 491: } else if (strcmp(options.proxy_command, "-") == 0) {
1.286 djm 492: if ((ssh_packet_set_connection(ssh,
493: STDIN_FILENO, STDOUT_FILENO)) == NULL)
494: return -1; /* ssh_packet_set_connection logs error */
495: return 0;
1.241 djm 496: } else if (options.proxy_use_fdpass) {
1.286 djm 497: return ssh_proxy_fdpass_connect(ssh, host, port,
1.241 djm 498: options.proxy_command);
499: }
1.286 djm 500: return ssh_proxy_connect(ssh, host, port, options.proxy_command);
1.241 djm 501: }
502:
1.235 djm 503: static void
504: send_client_banner(int connection_out, int minor1)
505: {
506: /* Send our own protocol version identification. */
1.276 djm 507: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
508: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
1.270 markus 509: if (atomicio(vwrite, connection_out, client_version_string,
1.235 djm 510: strlen(client_version_string)) != strlen(client_version_string))
511: fatal("write: %.100s", strerror(errno));
512: chop(client_version_string);
513: debug("Local version string %.100s", client_version_string);
514: }
515:
1.43 markus 516: /*
1.39 deraadt 517: * Waits for the server identification string, and sends our own
518: * identification string.
519: */
1.213 andreas 520: void
1.202 djm 521: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 522: {
1.38 markus 523: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 524: int remote_major, remote_minor, mismatch;
1.38 markus 525: int connection_in = packet_get_connection_in();
526: int connection_out = packet_get_connection_out();
1.185 djm 527: u_int i, n;
1.202 djm 528: size_t len;
1.282 djm 529: int rc;
1.38 markus 530:
1.275 djm 531: send_client_banner(connection_out, 0);
1.235 djm 532:
1.163 avsm 533: /* Read other side's version identification. */
1.185 djm 534: for (n = 0;;) {
1.75 markus 535: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 536: if (timeout_ms > 0) {
1.282 djm 537: rc = waitrfd(connection_in, &timeout_ms);
538: if (rc == -1 && errno == ETIMEDOUT) {
1.202 djm 539: fatal("Connection timed out during "
540: "banner exchange");
1.282 djm 541: } else if (rc == -1) {
542: fatal("%s: %s",
543: __func__, strerror(errno));
1.202 djm 544: }
545: }
546:
1.270 markus 547: len = atomicio(read, connection_in, &buf[i], 1);
1.167 djm 548: if (len != 1 && errno == EPIPE)
1.202 djm 549: fatal("ssh_exchange_identification: "
550: "Connection closed by remote host");
1.163 avsm 551: else if (len != 1)
1.202 djm 552: fatal("ssh_exchange_identification: "
553: "read: %.100s", strerror(errno));
1.75 markus 554: if (buf[i] == '\r') {
555: buf[i] = '\n';
556: buf[i + 1] = 0;
557: continue; /**XXX wait for \n */
558: }
559: if (buf[i] == '\n') {
560: buf[i + 1] = 0;
561: break;
562: }
1.185 djm 563: if (++n > 65536)
1.202 djm 564: fatal("ssh_exchange_identification: "
565: "No banner received");
1.38 markus 566: }
1.75 markus 567: buf[sizeof(buf) - 1] = 0;
1.76 markus 568: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 569: break;
1.75 markus 570: debug("ssh_exchange_identification: %s", buf);
1.38 markus 571: }
1.59 markus 572: server_version_string = xstrdup(buf);
1.38 markus 573:
1.40 markus 574: /*
575: * Check that the versions match. In future this might accept
576: * several versions and set appropriate flags to handle them.
577: */
1.59 markus 578: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
579: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 580: fatal("Bad remote protocol version identification: '%.100s'", buf);
581: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 582: remote_major, remote_minor, remote_version);
1.38 markus 583:
1.255 markus 584: active_state->compat = compat_datafellows(remote_version);
1.64 markus 585: mismatch = 0;
1.59 markus 586:
1.116 deraadt 587: switch (remote_major) {
1.276 djm 588: case 2:
589: break;
1.64 markus 590: case 1:
1.276 djm 591: if (remote_minor != 99)
1.64 markus 592: mismatch = 1;
593: break;
1.68 markus 594: default:
1.64 markus 595: mismatch = 1;
596: break;
1.38 markus 597: }
1.64 markus 598: if (mismatch)
1.38 markus 599: fatal("Protocol major versions differ: %d vs. %d",
1.275 djm 600: PROTOCOL_MAJOR_2, remote_major);
1.244 djm 601: if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
602: fatal("Server version \"%.100s\" uses unsafe key agreement; "
603: "refusing connection", remote_version);
1.243 djm 604: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
605: logit("Server version \"%.100s\" uses unsafe RSA signature "
606: "scheme; disabling use of RSA keys", remote_version);
1.59 markus 607: chop(server_version_string);
1.1 deraadt 608: }
609:
1.96 markus 610: /* defaults to 'no' */
1.109 itojun 611: static int
1.112 markus 612: confirm(const char *prompt)
1.1 deraadt 613: {
1.119 markus 614: const char *msg, *again = "Please type 'yes' or 'no': ";
615: char *p;
616: int ret = -1;
1.96 markus 617:
618: if (options.batch_mode)
619: return 0;
1.119 markus 620: for (msg = prompt;;msg = again) {
621: p = read_passphrase(msg, RP_ECHO);
1.289 ! djm 622: if (p == NULL)
! 623: return 0;
! 624: p[strcspn(p, "\n")] = '\0';
! 625: if (p[0] == '\0' || strcasecmp(p, "no") == 0)
1.119 markus 626: ret = 0;
1.289 ! djm 627: else if (strcasecmp(p, "yes") == 0)
1.119 markus 628: ret = 1;
1.238 djm 629: free(p);
1.119 markus 630: if (ret != -1)
631: return ret;
1.1 deraadt 632: }
633: }
634:
1.219 djm 635: static int
1.279 markus 636: check_host_cert(const char *host, const struct sshkey *host_key)
1.219 djm 637: {
638: const char *reason;
639:
640: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
641: error("%s", reason);
642: return 0;
643: }
1.249 djm 644: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 645: error("Certificate for %s contains unsupported "
646: "critical options(s)", host);
1.219 djm 647: return 0;
648: }
649: return 1;
650: }
651:
1.229 djm 652: static int
653: sockaddr_is_local(struct sockaddr *hostaddr)
654: {
655: switch (hostaddr->sa_family) {
656: case AF_INET:
657: return (ntohl(((struct sockaddr_in *)hostaddr)->
658: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
659: case AF_INET6:
660: return IN6_IS_ADDR_LOOPBACK(
661: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
662: default:
663: return 0;
664: }
665: }
666:
667: /*
668: * Prepare the hostname and ip address strings that are used to lookup
669: * host keys in known_hosts files. These may have a port number appended.
670: */
671: void
672: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
673: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
674: {
675: char ntop[NI_MAXHOST];
676:
677: /*
678: * We don't have the remote ip-address for connections
679: * using a proxy command
680: */
681: if (hostfile_ipaddr != NULL) {
682: if (options.proxy_command == NULL) {
683: if (getnameinfo(hostaddr, hostaddr->sa_len,
684: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 685: fatal("%s: getnameinfo failed", __func__);
1.229 djm 686: *hostfile_ipaddr = put_host_port(ntop, port);
687: } else {
688: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
689: "command>");
690: }
691: }
692:
693: /*
694: * Allow the user to record the key under a different name or
695: * differentiate a non-standard port. This is useful for ssh
696: * tunneling over forwarded connections or if you run multiple
697: * sshd's on different ports on the same machine.
698: */
699: if (hostfile_hostname != NULL) {
700: if (options.host_key_alias != NULL) {
701: *hostfile_hostname = xstrdup(options.host_key_alias);
702: debug("using hostkeyalias: %s", *hostfile_hostname);
703: } else {
704: *hostfile_hostname = put_host_port(hostname, port);
705: }
706: }
707: }
708:
1.39 deraadt 709: /*
1.108 markus 710: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 711: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 712: */
1.197 dtucker 713: #define RDRW 0
714: #define RDONLY 1
715: #define ROQUIET 2
1.109 itojun 716: static int
1.197 dtucker 717: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 718: struct sshkey *host_key, int readonly,
1.234 djm 719: char **user_hostfiles, u_int num_user_hostfiles,
720: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 721: {
1.234 djm 722: HostStatus host_status;
723: HostStatus ip_status;
1.279 markus 724: struct sshkey *raw_key = NULL;
1.189 dtucker 725: char *ip = NULL, *host = NULL;
1.204 grunk 726: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 727: char msg[1024];
1.234 djm 728: const char *type;
729: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 730: int len, cancelled_forwarding = 0;
1.234 djm 731: int local = sockaddr_is_local(hostaddr);
1.280 markus 732: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 733: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 734: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 735: u_int i;
1.49 markus 736:
737: /*
738: * Force accepting of the host key for loopback/localhost. The
739: * problem is that if the home directory is NFS-mounted to multiple
740: * machines, localhost will refer to a different machine in each of
741: * them, and the user will get bogus HOST_CHANGED warnings. This
742: * essentially disables host authentication for localhost; however,
743: * this is probably not a real problem.
744: */
1.111 markus 745: if (options.no_host_authentication_for_localhost == 1 && local &&
746: options.host_key_alias == NULL) {
1.88 markus 747: debug("Forcing accepting of host key for "
748: "loopback/localhost.");
1.108 markus 749: return 0;
1.49 markus 750: }
1.42 markus 751:
752: /*
1.229 djm 753: * Prepare the hostname and address strings used for hostkey lookup.
754: * In some cases, these will have a port number appended.
1.42 markus 755: */
1.229 djm 756: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 757:
758: /*
1.88 markus 759: * Turn off check_host_ip if the connection is to localhost, via proxy
760: * command or if we don't have a hostname to compare with
761: */
1.189 dtucker 762: if (options.check_host_ip && (local ||
763: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 764: options.check_host_ip = 0;
1.86 markus 765:
1.229 djm 766: host_hostkeys = init_hostkeys();
1.234 djm 767: for (i = 0; i < num_user_hostfiles; i++)
768: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
769: for (i = 0; i < num_system_hostfiles; i++)
770: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 771:
772: ip_hostkeys = NULL;
773: if (!want_cert && options.check_host_ip) {
774: ip_hostkeys = init_hostkeys();
1.234 djm 775: for (i = 0; i < num_user_hostfiles; i++)
776: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
777: for (i = 0; i < num_system_hostfiles; i++)
778: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 779: }
1.38 markus 780:
1.219 djm 781: retry:
1.229 djm 782: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 783: want_cert = sshkey_is_cert(host_key);
784: type = sshkey_type(host_key);
1.219 djm 785:
1.46 markus 786: /*
1.170 djm 787: * Check if the host key is present in the user's list of known
1.40 markus 788: * hosts or in the systemwide list.
789: */
1.229 djm 790: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
791: &host_found);
792:
1.40 markus 793: /*
794: * Also perform check for the ip address, skip the check if we are
1.219 djm 795: * localhost, looking for a certificate, or the hostname was an ip
796: * address to begin with.
1.40 markus 797: */
1.229 djm 798: if (!want_cert && ip_hostkeys != NULL) {
799: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
800: &ip_found);
1.38 markus 801: if (host_status == HOST_CHANGED &&
1.229 djm 802: (ip_status != HOST_CHANGED ||
803: (ip_found != NULL &&
1.280 markus 804: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 805: host_ip_differ = 1;
806: } else
807: ip_status = host_status;
808:
809: switch (host_status) {
810: case HOST_OK:
811: /* The host is known and the key matches. */
1.219 djm 812: debug("Host '%.200s' is known and matches the %s host %s.",
813: host, type, want_cert ? "certificate" : "key");
1.229 djm 814: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
815: host_found->file, host_found->line);
1.281 djm 816: if (want_cert &&
817: !check_host_cert(options.host_key_alias == NULL ?
818: hostname : options.host_key_alias, host_key))
1.219 djm 819: goto fail;
1.88 markus 820: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 821: if (readonly || want_cert)
1.138 itojun 822: logit("%s host key for IP address "
1.108 markus 823: "'%.128s' not in list of known hosts.",
824: type, ip);
1.234 djm 825: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 826: host_key, options.hash_known_hosts))
1.138 itojun 827: logit("Failed to add the %s host key for IP "
1.108 markus 828: "address '%.128s' to the list of known "
1.262 dtucker 829: "hosts (%.500s).", type, ip,
1.234 djm 830: user_hostfiles[0]);
1.88 markus 831: else
1.138 itojun 832: logit("Warning: Permanently added the %s host "
1.108 markus 833: "key for IP address '%.128s' to the list "
834: "of known hosts.", type, ip);
1.209 grunk 835: } else if (options.visual_host_key) {
1.259 djm 836: fp = sshkey_fingerprint(host_key,
1.254 djm 837: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 838: ra = sshkey_fingerprint(host_key,
1.254 djm 839: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 840: if (fp == NULL || ra == NULL)
841: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 842: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 843: free(ra);
844: free(fp);
1.38 markus 845: }
1.257 djm 846: hostkey_trusted = 1;
1.38 markus 847: break;
848: case HOST_NEW:
1.197 dtucker 849: if (options.host_key_alias == NULL && port != 0 &&
850: port != SSH_DEFAULT_PORT) {
851: debug("checking without port identifier");
1.212 stevesk 852: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 853: ROQUIET, user_hostfiles, num_user_hostfiles,
854: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 855: debug("found matching key w/out port");
856: break;
857: }
858: }
1.219 djm 859: if (readonly || want_cert)
1.108 markus 860: goto fail;
1.38 markus 861: /* The host is new. */
1.285 djm 862: if (options.strict_host_key_checking ==
863: SSH_STRICT_HOSTKEY_YES) {
1.108 markus 864: /*
865: * User has requested strict host key checking. We
866: * will not add the host key automatically. The only
867: * alternative left is to abort.
868: */
869: error("No %s host key is known for %.200s and you "
870: "have requested strict checking.", type, host);
871: goto fail;
1.285 djm 872: } else if (options.strict_host_key_checking ==
873: SSH_STRICT_HOSTKEY_ASK) {
1.145 jakob 874: char msg1[1024], msg2[1024];
875:
1.229 djm 876: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 877: snprintf(msg1, sizeof(msg1),
1.168 djm 878: "\nbut keys of different type are already"
879: " known for this host.");
1.145 jakob 880: else
881: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 882: /* The default */
1.259 djm 883: fp = sshkey_fingerprint(host_key,
1.254 djm 884: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 885: ra = sshkey_fingerprint(host_key,
1.254 djm 886: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 887: if (fp == NULL || ra == NULL)
888: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 889: msg2[0] = '\0';
890: if (options.verify_host_key_dns) {
1.153 jakob 891: if (matching_host_key_dns)
1.145 jakob 892: snprintf(msg2, sizeof(msg2),
893: "Matching host key fingerprint"
894: " found in DNS.\n");
895: else
896: snprintf(msg2, sizeof(msg2),
897: "No matching host key fingerprint"
898: " found in DNS.\n");
899: }
1.119 markus 900: snprintf(msg, sizeof(msg),
1.108 markus 901: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 902: "established%s\n"
1.209 grunk 903: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 904: "Are you sure you want to continue connecting "
1.132 markus 905: "(yes/no)? ",
1.209 grunk 906: host, ip, msg1, type, fp,
907: options.visual_host_key ? "\n" : "",
908: options.visual_host_key ? ra : "",
909: msg2);
1.238 djm 910: free(ra);
911: free(fp);
1.119 markus 912: if (!confirm(msg))
1.108 markus 913: goto fail;
1.257 djm 914: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 915: }
1.161 djm 916: /*
1.285 djm 917: * If in "new" or "off" strict mode, add the key automatically
918: * to the local known_hosts file.
1.161 djm 919: */
1.88 markus 920: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 921: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 922: hostp = hostline;
1.161 djm 923: if (options.hash_known_hosts) {
924: /* Add hash of host and IP separately */
1.234 djm 925: r = add_host_to_hostfile(user_hostfiles[0],
926: host, host_key, options.hash_known_hosts) &&
927: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 928: host_key, options.hash_known_hosts);
929: } else {
930: /* Add unhashed "host,ip" */
1.234 djm 931: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 932: hostline, host_key,
933: options.hash_known_hosts);
934: }
935: } else {
1.234 djm 936: r = add_host_to_hostfile(user_hostfiles[0], host,
937: host_key, options.hash_known_hosts);
1.38 markus 938: hostp = host;
1.161 djm 939: }
1.38 markus 940:
1.161 djm 941: if (!r)
1.138 itojun 942: logit("Failed to add the host to the list of known "
1.234 djm 943: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 944: else
1.138 itojun 945: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 946: "list of known hosts.", hostp, type);
1.38 markus 947: break;
1.220 djm 948: case HOST_REVOKED:
949: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
950: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
951: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
952: error("The %s host key for %s is marked as revoked.", type, host);
953: error("This could mean that a stolen key is being used to");
954: error("impersonate this host.");
955:
956: /*
957: * If strict host key checking is in use, the user will have
958: * to edit the key manually and we can only abort.
959: */
1.285 djm 960: if (options.strict_host_key_checking !=
961: SSH_STRICT_HOSTKEY_OFF) {
1.220 djm 962: error("%s host key for %.200s was revoked and you have "
963: "requested strict checking.", type, host);
964: goto fail;
965: }
966: goto continue_unsafe;
967:
1.38 markus 968: case HOST_CHANGED:
1.219 djm 969: if (want_cert) {
970: /*
971: * This is only a debug() since it is valid to have
972: * CAs with wildcard DNS matches that don't match
973: * all hosts that one might visit.
974: */
975: debug("Host certificate authority does not "
1.229 djm 976: "match %s in %s:%lu", CA_MARKER,
977: host_found->file, host_found->line);
1.219 djm 978: goto fail;
979: }
1.197 dtucker 980: if (readonly == ROQUIET)
981: goto fail;
1.38 markus 982: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 983: char *key_msg;
1.38 markus 984: if (ip_status == HOST_NEW)
1.158 avsm 985: key_msg = "is unknown";
1.38 markus 986: else if (ip_status == HOST_OK)
1.158 avsm 987: key_msg = "is unchanged";
1.38 markus 988: else
1.158 avsm 989: key_msg = "has a different value";
1.38 markus 990: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
991: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
992: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 993: error("The %s host key for %s has changed,", type, host);
1.208 ian 994: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 995: error("%s. This could either mean that", key_msg);
1.38 markus 996: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 997: error("and its host key have changed at the same time.");
1.88 markus 998: if (ip_status != HOST_NEW)
1.229 djm 999: error("Offending key for IP in %s:%lu",
1000: ip_found->file, ip_found->line);
1.38 markus 1001: }
1002: /* The host key has changed. */
1.150 jakob 1003: warn_changed_key(host_key);
1.38 markus 1004: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1005: user_hostfiles[0]);
1.280 markus 1006: error("Offending %s key in %s:%lu",
1007: sshkey_type(host_found->key),
1.229 djm 1008: host_found->file, host_found->line);
1.38 markus 1009:
1.40 markus 1010: /*
1011: * If strict host key checking is in use, the user will have
1012: * to edit the key manually and we can only abort.
1013: */
1.285 djm 1014: if (options.strict_host_key_checking !=
1015: SSH_STRICT_HOSTKEY_OFF) {
1.108 markus 1016: error("%s host key for %.200s has changed and you have "
1017: "requested strict checking.", type, host);
1018: goto fail;
1019: }
1.38 markus 1020:
1.220 djm 1021: continue_unsafe:
1.40 markus 1022: /*
1023: * If strict host key checking has not been requested, allow
1.144 djm 1024: * the connection but without MITM-able authentication or
1.194 stevesk 1025: * forwarding.
1.40 markus 1026: */
1.38 markus 1027: if (options.password_authentication) {
1.108 markus 1028: error("Password authentication is disabled to avoid "
1029: "man-in-the-middle attacks.");
1.38 markus 1030: options.password_authentication = 0;
1.210 dtucker 1031: cancelled_forwarding = 1;
1.144 djm 1032: }
1033: if (options.kbd_interactive_authentication) {
1034: error("Keyboard-interactive authentication is disabled"
1035: " to avoid man-in-the-middle attacks.");
1036: options.kbd_interactive_authentication = 0;
1037: options.challenge_response_authentication = 0;
1.210 dtucker 1038: cancelled_forwarding = 1;
1.144 djm 1039: }
1040: if (options.challenge_response_authentication) {
1041: error("Challenge/response authentication is disabled"
1042: " to avoid man-in-the-middle attacks.");
1043: options.challenge_response_authentication = 0;
1.210 dtucker 1044: cancelled_forwarding = 1;
1.38 markus 1045: }
1046: if (options.forward_agent) {
1.108 markus 1047: error("Agent forwarding is disabled to avoid "
1048: "man-in-the-middle attacks.");
1.38 markus 1049: options.forward_agent = 0;
1.210 dtucker 1050: cancelled_forwarding = 1;
1.83 markus 1051: }
1052: if (options.forward_x11) {
1.108 markus 1053: error("X11 forwarding is disabled to avoid "
1054: "man-in-the-middle attacks.");
1.83 markus 1055: options.forward_x11 = 0;
1.210 dtucker 1056: cancelled_forwarding = 1;
1.83 markus 1057: }
1.108 markus 1058: if (options.num_local_forwards > 0 ||
1059: options.num_remote_forwards > 0) {
1060: error("Port forwarding is disabled to avoid "
1061: "man-in-the-middle attacks.");
1062: options.num_local_forwards =
1.118 deraadt 1063: options.num_remote_forwards = 0;
1.210 dtucker 1064: cancelled_forwarding = 1;
1.194 stevesk 1065: }
1066: if (options.tun_open != SSH_TUNMODE_NO) {
1067: error("Tunnel forwarding is disabled to avoid "
1068: "man-in-the-middle attacks.");
1069: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1070: cancelled_forwarding = 1;
1.38 markus 1071: }
1.210 dtucker 1072: if (options.exit_on_forward_failure && cancelled_forwarding)
1073: fatal("Error: forwarding disabled due to host key "
1074: "check failure");
1075:
1.40 markus 1076: /*
1077: * XXX Should permit the user to change to use the new id.
1078: * This could be done by converting the host key to an
1079: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1080: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1081: * accept the authentication.
1082: */
1.38 markus 1083: break;
1.132 markus 1084: case HOST_FOUND:
1085: fatal("internal error");
1086: break;
1.88 markus 1087: }
1088:
1089: if (options.check_host_ip && host_status != HOST_CHANGED &&
1090: ip_status == HOST_CHANGED) {
1.119 markus 1091: snprintf(msg, sizeof(msg),
1092: "Warning: the %s host key for '%.200s' "
1093: "differs from the key for the IP address '%.128s'"
1.229 djm 1094: "\nOffending key for IP in %s:%lu",
1095: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1096: if (host_status == HOST_OK) {
1097: len = strlen(msg);
1098: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1099: "\nMatching host key in %s:%lu",
1100: host_found->file, host_found->line);
1.119 markus 1101: }
1.285 djm 1102: if (options.strict_host_key_checking ==
1103: SSH_STRICT_HOSTKEY_ASK) {
1.119 markus 1104: strlcat(msg, "\nAre you sure you want "
1105: "to continue connecting (yes/no)? ", sizeof(msg));
1106: if (!confirm(msg))
1.108 markus 1107: goto fail;
1.285 djm 1108: } else if (options.strict_host_key_checking !=
1109: SSH_STRICT_HOSTKEY_OFF) {
1110: logit("%s", msg);
1111: error("Exiting, you have requested strict checking.");
1112: goto fail;
1.119 markus 1113: } else {
1.143 djm 1114: logit("%s", msg);
1.88 markus 1115: }
1.257 djm 1116: }
1117:
1118: if (!hostkey_trusted && options.update_hostkeys) {
1119: debug("%s: hostkey not known or explicitly trusted: "
1120: "disabling UpdateHostkeys", __func__);
1121: options.update_hostkeys = 0;
1.38 markus 1122: }
1.82 provos 1123:
1.238 djm 1124: free(ip);
1125: free(host);
1.229 djm 1126: if (host_hostkeys != NULL)
1127: free_hostkeys(host_hostkeys);
1128: if (ip_hostkeys != NULL)
1129: free_hostkeys(ip_hostkeys);
1.108 markus 1130: return 0;
1131:
1132: fail:
1.220 djm 1133: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1134: /*
1135: * No matching certificate. Downgrade cert to raw key and
1136: * search normally.
1137: */
1138: debug("No matching CA found. Retry with plain key");
1.280 markus 1139: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1140: fatal("%s: sshkey_from_private: %s",
1141: __func__, ssh_err(r));
1142: if ((r = sshkey_drop_cert(raw_key)) != 0)
1143: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1144: host_key = raw_key;
1145: goto retry;
1146: }
1147: if (raw_key != NULL)
1.280 markus 1148: sshkey_free(raw_key);
1.238 djm 1149: free(ip);
1150: free(host);
1.229 djm 1151: if (host_hostkeys != NULL)
1152: free_hostkeys(host_hostkeys);
1153: if (ip_hostkeys != NULL)
1154: free_hostkeys(ip_hostkeys);
1.108 markus 1155: return -1;
1156: }
1157:
1.140 jakob 1158: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1159: int
1.279 markus 1160: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1161: {
1.267 djm 1162: u_int i;
1.250 djm 1163: int r = -1, flags = 0;
1.267 djm 1164: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1165: struct sshkey *plain = NULL;
1.229 djm 1166:
1.252 djm 1167: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1168: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1169: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1170: r = -1;
1171: goto out;
1172: }
1173:
1.267 djm 1174: if (sshkey_is_cert(host_key)) {
1175: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1176: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1177: error("%s: fingerprint CA key: %s",
1178: __func__, ssh_err(r));
1179: r = -1;
1180: goto out;
1181: }
1182: sshkey_format_cert_validity(host_key->cert,
1183: valid, sizeof(valid));
1184: debug("Server host certificate: %s %s, serial %llu "
1185: "ID \"%s\" CA %s %s valid %s",
1186: sshkey_ssh_name(host_key), fp,
1.269 djm 1187: (unsigned long long)host_key->cert->serial,
1188: host_key->cert->key_id,
1.267 djm 1189: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1190: valid);
1191: for (i = 0; i < host_key->cert->nprincipals; i++) {
1192: debug2("Server host certificate hostname: %s",
1193: host_key->cert->principals[i]);
1194: }
1195: } else {
1.276 djm 1196: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1197: }
1.252 djm 1198:
1199: if (sshkey_equal(previous_host_key, host_key)) {
1200: debug2("%s: server host key %s %s matches cached key",
1201: __func__, sshkey_type(host_key), fp);
1202: r = 0;
1203: goto out;
1204: }
1205:
1206: /* Check in RevokedHostKeys file if specified */
1207: if (options.revoked_host_keys != NULL) {
1208: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1209: switch (r) {
1210: case 0:
1211: break; /* not revoked */
1212: case SSH_ERR_KEY_REVOKED:
1213: error("Host key %s %s revoked by file %s",
1214: sshkey_type(host_key), fp,
1215: options.revoked_host_keys);
1216: r = -1;
1217: goto out;
1218: default:
1219: error("Error checking host key %s %s in "
1220: "revoked keys file %s: %s", sshkey_type(host_key),
1221: fp, options.revoked_host_keys, ssh_err(r));
1222: r = -1;
1223: goto out;
1224: }
1.250 djm 1225: }
1226:
1.247 djm 1227: if (options.verify_host_key_dns) {
1228: /*
1229: * XXX certs are not yet supported for DNS, so downgrade
1230: * them and try the plain key.
1231: */
1.252 djm 1232: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1233: goto out;
1234: if (sshkey_is_cert(plain))
1235: sshkey_drop_cert(plain);
1.247 djm 1236: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1237: if (flags & DNS_VERIFY_FOUND) {
1238: if (options.verify_host_key_dns == 1 &&
1239: flags & DNS_VERIFY_MATCH &&
1240: flags & DNS_VERIFY_SECURE) {
1.250 djm 1241: r = 0;
1.252 djm 1242: goto out;
1.247 djm 1243: }
1244: if (flags & DNS_VERIFY_MATCH) {
1245: matching_host_key_dns = 1;
1246: } else {
1.287 djm 1247: warn_changed_key(plain);
1248: error("Update the SSHFP RR in DNS "
1249: "with the new host key to get rid "
1250: "of this message.");
1.247 djm 1251: }
1.153 jakob 1252: }
1.140 jakob 1253: }
1254: }
1.250 djm 1255: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1256: options.user_hostfiles, options.num_user_hostfiles,
1257: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1258:
1.252 djm 1259: out:
1260: sshkey_free(plain);
1261: free(fp);
1.267 djm 1262: free(cafp);
1.250 djm 1263: if (r == 0 && host_key != NULL) {
1.280 markus 1264: sshkey_free(previous_host_key);
1265: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1266: }
1267:
1268: return r;
1.51 markus 1269: }
1.70 markus 1270:
1.51 markus 1271: /*
1272: * Starts a dialog with the server, and authenticates the current user on the
1273: * server. This does not need any extra privileges. The basic connection
1274: * to the server must already have been established before this is called.
1275: * If login fails, this function prints an error and never returns.
1276: * This function does not require super-user privileges.
1277: */
1278: void
1.120 markus 1279: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1280: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1281: {
1.241 djm 1282: char *host;
1.70 markus 1283: char *server_user, *local_user;
1284:
1285: local_user = xstrdup(pw->pw_name);
1286: server_user = options.user ? options.user : local_user;
1.51 markus 1287:
1288: /* Convert the user-supplied hostname into all lowercase. */
1289: host = xstrdup(orighost);
1.241 djm 1290: lowercase(host);
1.51 markus 1291:
1292: /* Exchange protocol version identification strings with the server. */
1.202 djm 1293: ssh_exchange_identification(timeout_ms);
1.51 markus 1294:
1295: /* Put the connection into non-blocking mode. */
1296: packet_set_nonblocking();
1297:
1298: /* key exchange */
1299: /* authenticate user */
1.261 dtucker 1300: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.276 djm 1301: ssh_kex2(host, hostaddr, port);
1302: ssh_userauth2(local_user, server_user, host, sensitive);
1.238 djm 1303: free(local_user);
1.97 markus 1304: }
1305:
1306: void
1307: ssh_put_password(char *password)
1308: {
1309: int size;
1310: char *padded;
1311:
1.99 deraadt 1312: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1313: packet_put_cstring(password);
1.99 deraadt 1314: return;
1315: }
1.272 deraadt 1316: size = ROUNDUP(strlen(password) + 1, 32);
1.179 djm 1317: padded = xcalloc(1, size);
1.97 markus 1318: strlcpy(padded, password, size);
1319: packet_put_string(padded, size);
1.245 djm 1320: explicit_bzero(padded, size);
1.238 djm 1321: free(padded);
1.132 markus 1322: }
1323:
1324: /* print all known host keys for a given host, but skip keys of given type */
1325: static int
1.279 markus 1326: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1327: {
1.242 djm 1328: int type[] = {
1329: KEY_RSA,
1330: KEY_DSA,
1331: KEY_ECDSA,
1332: KEY_ED25519,
1333: -1
1334: };
1.229 djm 1335: int i, ret = 0;
1336: char *fp, *ra;
1337: const struct hostkey_entry *found;
1.132 markus 1338:
1339: for (i = 0; type[i] != -1; i++) {
1340: if (type[i] == key->type)
1341: continue;
1.229 djm 1342: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1343: continue;
1.259 djm 1344: fp = sshkey_fingerprint(found->key,
1.254 djm 1345: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1346: ra = sshkey_fingerprint(found->key,
1.254 djm 1347: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1348: if (fp == NULL || ra == NULL)
1349: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1350: logit("WARNING: %s key found for host %s\n"
1351: "in %s:%lu\n"
1352: "%s key fingerprint %s.",
1353: key_type(found->key),
1354: found->host, found->file, found->line,
1355: key_type(found->key), fp);
1356: if (options.visual_host_key)
1357: logit("%s", ra);
1.238 djm 1358: free(ra);
1359: free(fp);
1.229 djm 1360: ret = 1;
1.132 markus 1361: }
1.229 djm 1362: return ret;
1.150 jakob 1363: }
1364:
1365: static void
1.279 markus 1366: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1367: {
1368: char *fp;
1369:
1.259 djm 1370: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1371: SSH_FP_DEFAULT);
1.259 djm 1372: if (fp == NULL)
1373: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1374:
1375: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1376: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1377: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1378: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1379: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1380: error("It is also possible that a host key has just been changed.");
1.150 jakob 1381: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.287 djm 1382: key_type(host_key), fp);
1.150 jakob 1383: error("Please contact your system administrator.");
1384:
1.238 djm 1385: free(fp);
1.171 reyk 1386: }
1387:
1388: /*
1389: * Execute a local command
1390: */
1391: int
1392: ssh_local_cmd(const char *args)
1393: {
1394: char *shell;
1395: pid_t pid;
1396: int status;
1.231 djm 1397: void (*osighand)(int);
1.171 reyk 1398:
1399: if (!options.permit_local_command ||
1400: args == NULL || !*args)
1401: return (1);
1402:
1.226 djm 1403: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1404: shell = _PATH_BSHELL;
1405:
1.231 djm 1406: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1407: pid = fork();
1408: if (pid == 0) {
1.232 djm 1409: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1410: debug3("Executing %s -c \"%s\"", shell, args);
1411: execl(shell, shell, "-c", args, (char *)NULL);
1412: error("Couldn't execute %s -c \"%s\": %s",
1413: shell, args, strerror(errno));
1414: _exit(1);
1415: } else if (pid == -1)
1416: fatal("fork failed: %.100s", strerror(errno));
1417: while (waitpid(pid, &status, 0) == -1)
1418: if (errno != EINTR)
1419: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1420: signal(SIGCHLD, osighand);
1.171 reyk 1421:
1422: if (!WIFEXITED(status))
1423: return (1);
1424:
1425: return (WEXITSTATUS(status));
1.266 jcs 1426: }
1427:
1428: void
1.279 markus 1429: maybe_add_key_to_agent(char *authfile, struct sshkey *private, char *comment,
1.266 jcs 1430: char *passphrase)
1431: {
1432: int auth_sock = -1, r;
1433:
1434: if (options.add_keys_to_agent == 0)
1435: return;
1436:
1437: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1438: debug3("no authentication agent, not adding key");
1439: return;
1440: }
1441:
1442: if (options.add_keys_to_agent == 2 &&
1443: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1444: debug3("user denied adding this key");
1.273 dtucker 1445: close(auth_sock);
1.266 jcs 1446: return;
1447: }
1448:
1449: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1450: (options.add_keys_to_agent == 3))) == 0)
1451: debug("identity added to agent: %s", authfile);
1452: else
1453: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1454: close(auth_sock);
1.1 deraadt 1455: }
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