Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.284
1.284 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.283 2017/07/01 13:50:45 djm Exp $ */
1.1 deraadt 2: /*
1.39 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
1.78 deraadt 8: *
9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 14: */
1.1 deraadt 15:
1.174 stevesk 16: #include <sys/types.h>
17: #include <sys/wait.h>
1.175 stevesk 18: #include <sys/stat.h>
1.187 stevesk 19: #include <sys/socket.h>
1.195 stevesk 20: #include <sys/time.h>
1.187 stevesk 21:
22: #include <netinet/in.h>
1.172 stevesk 23:
1.176 stevesk 24: #include <ctype.h>
1.190 stevesk 25: #include <errno.h>
1.216 dtucker 26: #include <fcntl.h>
1.191 stevesk 27: #include <netdb.h>
1.172 stevesk 28: #include <paths.h>
1.282 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 *);
1.284 ! djm 74: static void warn_missing_key(struct sshkey *);
1.132 markus 75:
1.239 djm 76: /* Expand a proxy command */
77: static char *
78: expand_proxy_command(const char *proxy_command, const char *user,
79: const char *host, int port)
80: {
81: char *tmp, *ret, strport[NI_MAXSERV];
82:
1.241 djm 83: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 84: xasprintf(&tmp, "exec %s", proxy_command);
85: ret = percent_expand(tmp, "h", host, "p", strport,
86: "r", options.user, (char *)NULL);
87: free(tmp);
88: return ret;
89: }
90:
91: /*
92: * Connect to the given ssh server using a proxy command that passes a
93: * a connected fd back to us.
94: */
95: static int
96: ssh_proxy_fdpass_connect(const char *host, u_short port,
97: const char *proxy_command)
98: {
99: char *command_string;
100: int sp[2], sock;
101: pid_t pid;
102: char *shell;
103:
104: if ((shell = getenv("SHELL")) == NULL)
105: shell = _PATH_BSHELL;
106:
107: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
108: fatal("Could not create socketpair to communicate with "
109: "proxy dialer: %.100s", strerror(errno));
110:
111: command_string = expand_proxy_command(proxy_command, options.user,
112: host, port);
113: debug("Executing proxy dialer command: %.500s", command_string);
114:
115: /* Fork and execute the proxy command. */
116: if ((pid = fork()) == 0) {
117: char *argv[10];
118:
119: /* Child. Permanently give up superuser privileges. */
120: permanently_drop_suid(original_real_uid);
121:
122: close(sp[1]);
123: /* Redirect stdin and stdout. */
124: if (sp[0] != 0) {
125: if (dup2(sp[0], 0) < 0)
126: perror("dup2 stdin");
127: }
128: if (sp[0] != 1) {
129: if (dup2(sp[0], 1) < 0)
130: perror("dup2 stdout");
131: }
132: if (sp[0] >= 2)
133: close(sp[0]);
134:
135: /*
136: * Stderr is left as it is so that error messages get
137: * printed on the user's terminal.
138: */
139: argv[0] = shell;
140: argv[1] = "-c";
141: argv[2] = command_string;
142: argv[3] = NULL;
143:
144: /*
145: * Execute the proxy command.
146: * Note that we gave up any extra privileges above.
147: */
148: execv(argv[0], argv);
149: perror(argv[0]);
150: exit(1);
151: }
152: /* Parent. */
153: if (pid < 0)
154: fatal("fork failed: %.100s", strerror(errno));
155: close(sp[0]);
156: free(command_string);
157:
158: if ((sock = mm_receive_fd(sp[1])) == -1)
159: fatal("proxy dialer did not pass back a connection");
1.271 markus 160: close(sp[1]);
1.239 djm 161:
162: while (waitpid(pid, NULL, 0) == -1)
163: if (errno != EINTR)
164: fatal("Couldn't wait for child: %s", strerror(errno));
165:
166: /* Set the connection file descriptors. */
167: packet_set_connection(sock, sock);
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
1.124 markus 176: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 177: {
1.239 djm 178: char *command_string;
1.38 markus 179: int pin[2], pout[2];
1.69 deraadt 180: pid_t pid;
1.239 djm 181: char *shell;
1.237 markus 182:
1.226 djm 183: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 184: shell = _PATH_BSHELL;
1.38 markus 185:
186: /* Create pipes for communicating with the proxy. */
187: if (pipe(pin) < 0 || pipe(pout) < 0)
188: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 189: strerror(errno));
1.38 markus 190:
1.239 djm 191: command_string = expand_proxy_command(proxy_command, options.user,
192: host, port);
1.38 markus 193: debug("Executing proxy command: %.500s", command_string);
194:
195: /* Fork and execute the proxy command. */
196: if ((pid = fork()) == 0) {
197: char *argv[10];
198:
199: /* Child. Permanently give up superuser privileges. */
1.184 markus 200: permanently_drop_suid(original_real_uid);
1.38 markus 201:
202: /* Redirect stdin and stdout. */
203: close(pin[1]);
204: if (pin[0] != 0) {
205: if (dup2(pin[0], 0) < 0)
206: perror("dup2 stdin");
207: close(pin[0]);
208: }
209: close(pout[0]);
210: if (dup2(pout[1], 1) < 0)
211: perror("dup2 stdout");
212: /* Cannot be 1 because pin allocated two descriptors. */
213: close(pout[1]);
214:
215: /* Stderr is left as it is so that error messages get
216: printed on the user's terminal. */
1.201 djm 217: argv[0] = shell;
1.38 markus 218: argv[1] = "-c";
219: argv[2] = command_string;
220: argv[3] = NULL;
221:
222: /* Execute the proxy command. Note that we gave up any
223: extra privileges above. */
1.232 djm 224: signal(SIGPIPE, SIG_DFL);
1.89 markus 225: execv(argv[0], argv);
226: perror(argv[0]);
1.38 markus 227: exit(1);
228: }
229: /* Parent. */
230: if (pid < 0)
231: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 232: else
233: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 234:
235: /* Close child side of the descriptors. */
236: close(pin[0]);
237: close(pout[1]);
238:
239: /* Free the command name. */
1.238 djm 240: free(command_string);
1.38 markus 241:
242: /* Set the connection file descriptors. */
243: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 244:
1.110 markus 245: /* Indicate OK return */
246: return 0;
1.227 djm 247: }
248:
249: void
250: ssh_kill_proxy_command(void)
251: {
252: /*
253: * Send SIGHUP to proxy command if used. We don't wait() in
254: * case it hangs and instead rely on init to reap the child
255: */
256: if (proxy_command_pid > 1)
1.228 djm 257: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 258: }
259:
1.39 deraadt 260: /*
261: * Creates a (possibly privileged) socket for use as the ssh connection.
262: */
1.109 itojun 263: static int
1.139 markus 264: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 265: {
1.240 djm 266: int sock, r, gaierr;
1.246 djm 267: struct addrinfo hints, *res = NULL;
1.1 deraadt 268:
1.217 dtucker 269: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 270: if (sock < 0) {
1.240 djm 271: error("socket: %s", strerror(errno));
1.216 dtucker 272: return -1;
273: }
274: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 275:
276: /* Bind the socket to an alternative local IP address */
1.240 djm 277: if (options.bind_address == NULL && !privileged)
1.105 markus 278: return sock;
279:
1.246 djm 280: if (options.bind_address) {
281: memset(&hints, 0, sizeof(hints));
282: hints.ai_family = ai->ai_family;
283: hints.ai_socktype = ai->ai_socktype;
284: hints.ai_protocol = ai->ai_protocol;
285: hints.ai_flags = AI_PASSIVE;
286: gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
287: if (gaierr) {
288: error("getaddrinfo: %s: %s", options.bind_address,
289: ssh_gai_strerror(gaierr));
290: close(sock);
291: return -1;
292: }
1.105 markus 293: }
1.240 djm 294: /*
295: * If we are running as root and want to connect to a privileged
296: * port, bind our own socket to a privileged port.
297: */
298: if (privileged) {
299: PRIV_START;
1.246 djm 300: r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
1.240 djm 301: PRIV_END;
302: if (r < 0) {
303: error("bindresvport_sa: af=%d %s", ai->ai_family,
304: strerror(errno));
305: goto fail;
306: }
307: } else {
308: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
309: error("bind: %s: %s", options.bind_address,
310: strerror(errno));
311: fail:
312: close(sock);
313: freeaddrinfo(res);
314: return -1;
315: }
1.38 markus 316: }
1.246 djm 317: if (res != NULL)
318: freeaddrinfo(res);
1.38 markus 319: return sock;
1.1 deraadt 320: }
321:
1.282 djm 322: /*
323: * Wait up to *timeoutp milliseconds for fd to be readable. Updates
324: * *timeoutp with time remaining.
325: * Returns 0 if fd ready or -1 on timeout or error (see errno).
326: */
327: static int
328: waitrfd(int fd, int *timeoutp)
329: {
330: struct pollfd pfd;
331: struct timeval t_start;
332: int oerrno, r;
333:
334: gettimeofday(&t_start, NULL);
335: pfd.fd = fd;
336: pfd.events = POLLIN;
337: for (; *timeoutp >= 0;) {
338: r = poll(&pfd, 1, *timeoutp);
339: oerrno = errno;
340: ms_subtract_diff(&t_start, timeoutp);
341: errno = oerrno;
342: if (r > 0)
343: return 0;
344: else if (r == -1 && errno != EAGAIN)
345: return -1;
346: else if (r == 0)
347: break;
348: }
349: /* timeout */
350: errno = ETIMEDOUT;
351: return -1;
352: }
353:
1.141 djm 354: static int
355: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 356: socklen_t addrlen, int *timeoutp)
1.141 djm 357: {
1.282 djm 358: int optval = 0;
359: socklen_t optlen = sizeof(optval);
1.141 djm 360:
1.282 djm 361: /* No timeout: just do a blocking connect() */
362: if (*timeoutp <= 0)
363: return connect(sockfd, serv_addr, addrlen);
1.141 djm 364:
1.156 djm 365: set_nonblock(sockfd);
1.282 djm 366: if (connect(sockfd, serv_addr, addrlen) == 0) {
367: /* Succeeded already? */
1.156 djm 368: unset_nonblock(sockfd);
1.282 djm 369: return 0;
370: } else if (errno != EINPROGRESS)
371: return -1;
372:
373: if (waitrfd(sockfd, timeoutp) == -1)
374: return -1;
1.141 djm 375:
1.282 djm 376: /* Completed or failed */
377: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, &optlen) == -1) {
378: debug("getsockopt: %s", strerror(errno));
379: return -1;
1.141 djm 380: }
1.282 djm 381: if (optval != 0) {
382: errno = optval;
383: return -1;
1.202 djm 384: }
1.282 djm 385: unset_nonblock(sockfd);
386: return 0;
1.141 djm 387: }
388:
1.39 deraadt 389: /*
1.49 markus 390: * Opens a TCP/IP connection to the remote server on the given host.
391: * The address of the remote host will be returned in hostaddr.
1.124 markus 392: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 393: * a privileged port will be allocated to make the connection.
1.124 markus 394: * This requires super-user privileges if needpriv is true.
1.39 deraadt 395: * Connection_attempts specifies the maximum number of tries (one per
396: * second). If proxy_command is non-NULL, it specifies the command (with %h
397: * and %p substituted for host and port, respectively) to use to contact
398: * the daemon.
399: */
1.241 djm 400: static int
401: ssh_connect_direct(const char *host, struct addrinfo *aitop,
402: struct sockaddr_storage *hostaddr, u_short port, int family,
403: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
1.1 deraadt 404: {
1.90 markus 405: int on = 1;
1.49 markus 406: int sock = -1, attempt;
1.90 markus 407: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 408: struct addrinfo *ai;
1.38 markus 409:
1.265 djm 410: debug2("%s: needpriv %d", __func__, needpriv);
1.268 djm 411: memset(ntop, 0, sizeof(ntop));
412: memset(strport, 0, sizeof(strport));
1.38 markus 413:
1.181 markus 414: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 415: if (attempt > 0) {
416: /* Sleep a moment before retrying. */
417: sleep(1);
1.38 markus 418: debug("Trying again...");
1.200 markus 419: }
1.181 markus 420: /*
421: * Loop through addresses for this host, and try each one in
422: * sequence until the connection succeeds.
423: */
1.49 markus 424: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 425: if (ai->ai_family != AF_INET &&
426: ai->ai_family != AF_INET6)
1.49 markus 427: continue;
428: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
429: ntop, sizeof(ntop), strport, sizeof(strport),
430: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.265 djm 431: error("%s: getnameinfo failed", __func__);
1.49 markus 432: continue;
433: }
434: debug("Connecting to %.200s [%.100s] port %s.",
435: host, ntop, strport);
436:
437: /* Create a socket for connecting. */
1.139 markus 438: sock = ssh_create_socket(needpriv, ai);
1.49 markus 439: if (sock < 0)
1.110 markus 440: /* Any error is already output */
1.49 markus 441: continue;
442:
1.141 djm 443: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 444: timeout_ms) >= 0) {
1.49 markus 445: /* Successful connection. */
1.102 markus 446: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 447: break;
1.49 markus 448: } else {
1.131 itojun 449: debug("connect to address %s port %s: %s",
450: ntop, strport, strerror(errno));
1.38 markus 451: close(sock);
1.181 markus 452: sock = -1;
1.38 markus 453: }
454: }
1.181 markus 455: if (sock != -1)
1.49 markus 456: break; /* Successful connection. */
1.38 markus 457: }
1.49 markus 458:
1.38 markus 459: /* Return failure if we didn't get a successful connection. */
1.181 markus 460: if (sock == -1) {
1.159 markus 461: error("ssh: connect to host %s port %s: %s",
1.130 itojun 462: host, strport, strerror(errno));
1.159 markus 463: return (-1);
1.130 itojun 464: }
1.38 markus 465:
466: debug("Connection established.");
1.90 markus 467:
1.155 markus 468: /* Set SO_KEEPALIVE if requested. */
1.202 djm 469: if (want_keepalive &&
1.90 markus 470: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
471: sizeof(on)) < 0)
472: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 473:
474: /* Set the connection. */
475: packet_set_connection(sock, sock);
1.1 deraadt 476:
1.110 markus 477: return 0;
1.59 markus 478: }
479:
1.241 djm 480: int
481: ssh_connect(const char *host, struct addrinfo *addrs,
482: struct sockaddr_storage *hostaddr, u_short port, int family,
483: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
484: {
485: if (options.proxy_command == NULL) {
486: return ssh_connect_direct(host, addrs, hostaddr, port, family,
487: connection_attempts, timeout_ms, want_keepalive, needpriv);
488: } else if (strcmp(options.proxy_command, "-") == 0) {
489: packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
490: return 0; /* Always succeeds */
491: } else if (options.proxy_use_fdpass) {
492: return ssh_proxy_fdpass_connect(host, port,
493: options.proxy_command);
494: }
495: return ssh_proxy_connect(host, port, options.proxy_command);
496: }
497:
1.235 djm 498: static void
499: send_client_banner(int connection_out, int minor1)
500: {
501: /* Send our own protocol version identification. */
1.276 djm 502: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
503: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
1.270 markus 504: if (atomicio(vwrite, connection_out, client_version_string,
1.235 djm 505: strlen(client_version_string)) != strlen(client_version_string))
506: fatal("write: %.100s", strerror(errno));
507: chop(client_version_string);
508: debug("Local version string %.100s", client_version_string);
509: }
510:
1.43 markus 511: /*
1.39 deraadt 512: * Waits for the server identification string, and sends our own
513: * identification string.
514: */
1.213 andreas 515: void
1.202 djm 516: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 517: {
1.38 markus 518: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 519: int remote_major, remote_minor, mismatch;
1.38 markus 520: int connection_in = packet_get_connection_in();
521: int connection_out = packet_get_connection_out();
1.185 djm 522: u_int i, n;
1.202 djm 523: size_t len;
1.282 djm 524: int rc;
1.38 markus 525:
1.275 djm 526: send_client_banner(connection_out, 0);
1.235 djm 527:
1.163 avsm 528: /* Read other side's version identification. */
1.185 djm 529: for (n = 0;;) {
1.75 markus 530: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 531: if (timeout_ms > 0) {
1.282 djm 532: rc = waitrfd(connection_in, &timeout_ms);
533: if (rc == -1 && errno == ETIMEDOUT) {
1.202 djm 534: fatal("Connection timed out during "
535: "banner exchange");
1.282 djm 536: } else if (rc == -1) {
537: fatal("%s: %s",
538: __func__, strerror(errno));
1.202 djm 539: }
540: }
541:
1.270 markus 542: len = atomicio(read, connection_in, &buf[i], 1);
1.167 djm 543: if (len != 1 && errno == EPIPE)
1.202 djm 544: fatal("ssh_exchange_identification: "
545: "Connection closed by remote host");
1.163 avsm 546: else if (len != 1)
1.202 djm 547: fatal("ssh_exchange_identification: "
548: "read: %.100s", strerror(errno));
1.75 markus 549: if (buf[i] == '\r') {
550: buf[i] = '\n';
551: buf[i + 1] = 0;
552: continue; /**XXX wait for \n */
553: }
554: if (buf[i] == '\n') {
555: buf[i + 1] = 0;
556: break;
557: }
1.185 djm 558: if (++n > 65536)
1.202 djm 559: fatal("ssh_exchange_identification: "
560: "No banner received");
1.38 markus 561: }
1.75 markus 562: buf[sizeof(buf) - 1] = 0;
1.76 markus 563: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 564: break;
1.75 markus 565: debug("ssh_exchange_identification: %s", buf);
1.38 markus 566: }
1.59 markus 567: server_version_string = xstrdup(buf);
1.38 markus 568:
1.40 markus 569: /*
570: * Check that the versions match. In future this might accept
571: * several versions and set appropriate flags to handle them.
572: */
1.59 markus 573: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
574: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 575: fatal("Bad remote protocol version identification: '%.100s'", buf);
576: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 577: remote_major, remote_minor, remote_version);
1.38 markus 578:
1.255 markus 579: active_state->compat = compat_datafellows(remote_version);
1.64 markus 580: mismatch = 0;
1.59 markus 581:
1.116 deraadt 582: switch (remote_major) {
1.276 djm 583: case 2:
584: break;
1.64 markus 585: case 1:
1.276 djm 586: if (remote_minor != 99)
1.64 markus 587: mismatch = 1;
588: break;
1.68 markus 589: default:
1.64 markus 590: mismatch = 1;
591: break;
1.38 markus 592: }
1.64 markus 593: if (mismatch)
1.38 markus 594: fatal("Protocol major versions differ: %d vs. %d",
1.275 djm 595: PROTOCOL_MAJOR_2, remote_major);
1.244 djm 596: if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
597: fatal("Server version \"%.100s\" uses unsafe key agreement; "
598: "refusing connection", remote_version);
1.243 djm 599: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
600: logit("Server version \"%.100s\" uses unsafe RSA signature "
601: "scheme; disabling use of RSA keys", remote_version);
1.59 markus 602: chop(server_version_string);
1.1 deraadt 603: }
604:
1.96 markus 605: /* defaults to 'no' */
1.109 itojun 606: static int
1.112 markus 607: confirm(const char *prompt)
1.1 deraadt 608: {
1.119 markus 609: const char *msg, *again = "Please type 'yes' or 'no': ";
610: char *p;
611: int ret = -1;
1.96 markus 612:
613: if (options.batch_mode)
614: return 0;
1.119 markus 615: for (msg = prompt;;msg = again) {
616: p = read_passphrase(msg, RP_ECHO);
617: if (p == NULL ||
618: (p[0] == '\0') || (p[0] == '\n') ||
619: strncasecmp(p, "no", 2) == 0)
620: ret = 0;
1.127 markus 621: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 622: ret = 1;
1.238 djm 623: free(p);
1.119 markus 624: if (ret != -1)
625: return ret;
1.1 deraadt 626: }
627: }
628:
1.219 djm 629: static int
1.279 markus 630: check_host_cert(const char *host, const struct sshkey *host_key)
1.219 djm 631: {
632: const char *reason;
633:
634: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
635: error("%s", reason);
636: return 0;
637: }
1.249 djm 638: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 639: error("Certificate for %s contains unsupported "
640: "critical options(s)", host);
1.219 djm 641: return 0;
642: }
643: return 1;
644: }
645:
1.229 djm 646: static int
647: sockaddr_is_local(struct sockaddr *hostaddr)
648: {
649: switch (hostaddr->sa_family) {
650: case AF_INET:
651: return (ntohl(((struct sockaddr_in *)hostaddr)->
652: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
653: case AF_INET6:
654: return IN6_IS_ADDR_LOOPBACK(
655: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
656: default:
657: return 0;
658: }
659: }
660:
661: /*
662: * Prepare the hostname and ip address strings that are used to lookup
663: * host keys in known_hosts files. These may have a port number appended.
664: */
665: void
666: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
667: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
668: {
669: char ntop[NI_MAXHOST];
670:
671: /*
672: * We don't have the remote ip-address for connections
673: * using a proxy command
674: */
675: if (hostfile_ipaddr != NULL) {
676: if (options.proxy_command == NULL) {
677: if (getnameinfo(hostaddr, hostaddr->sa_len,
678: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 679: fatal("%s: getnameinfo failed", __func__);
1.229 djm 680: *hostfile_ipaddr = put_host_port(ntop, port);
681: } else {
682: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
683: "command>");
684: }
685: }
686:
687: /*
688: * Allow the user to record the key under a different name or
689: * differentiate a non-standard port. This is useful for ssh
690: * tunneling over forwarded connections or if you run multiple
691: * sshd's on different ports on the same machine.
692: */
693: if (hostfile_hostname != NULL) {
694: if (options.host_key_alias != NULL) {
695: *hostfile_hostname = xstrdup(options.host_key_alias);
696: debug("using hostkeyalias: %s", *hostfile_hostname);
697: } else {
698: *hostfile_hostname = put_host_port(hostname, port);
699: }
700: }
701: }
702:
1.39 deraadt 703: /*
1.108 markus 704: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 705: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 706: */
1.197 dtucker 707: #define RDRW 0
708: #define RDONLY 1
709: #define ROQUIET 2
1.109 itojun 710: static int
1.197 dtucker 711: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 712: struct sshkey *host_key, int readonly,
1.234 djm 713: char **user_hostfiles, u_int num_user_hostfiles,
714: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 715: {
1.234 djm 716: HostStatus host_status;
717: HostStatus ip_status;
1.279 markus 718: struct sshkey *raw_key = NULL;
1.189 dtucker 719: char *ip = NULL, *host = NULL;
1.204 grunk 720: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 721: char msg[1024];
1.234 djm 722: const char *type;
723: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 724: int len, cancelled_forwarding = 0;
1.234 djm 725: int local = sockaddr_is_local(hostaddr);
1.280 markus 726: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 727: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 728: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 729: u_int i;
1.49 markus 730:
731: /*
732: * Force accepting of the host key for loopback/localhost. The
733: * problem is that if the home directory is NFS-mounted to multiple
734: * machines, localhost will refer to a different machine in each of
735: * them, and the user will get bogus HOST_CHANGED warnings. This
736: * essentially disables host authentication for localhost; however,
737: * this is probably not a real problem.
738: */
1.111 markus 739: if (options.no_host_authentication_for_localhost == 1 && local &&
740: options.host_key_alias == NULL) {
1.88 markus 741: debug("Forcing accepting of host key for "
742: "loopback/localhost.");
1.108 markus 743: return 0;
1.49 markus 744: }
1.42 markus 745:
746: /*
1.229 djm 747: * Prepare the hostname and address strings used for hostkey lookup.
748: * In some cases, these will have a port number appended.
1.42 markus 749: */
1.229 djm 750: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 751:
752: /*
1.88 markus 753: * Turn off check_host_ip if the connection is to localhost, via proxy
754: * command or if we don't have a hostname to compare with
755: */
1.189 dtucker 756: if (options.check_host_ip && (local ||
757: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 758: options.check_host_ip = 0;
1.86 markus 759:
1.229 djm 760: host_hostkeys = init_hostkeys();
1.234 djm 761: for (i = 0; i < num_user_hostfiles; i++)
762: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
763: for (i = 0; i < num_system_hostfiles; i++)
764: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 765:
766: ip_hostkeys = NULL;
767: if (!want_cert && options.check_host_ip) {
768: ip_hostkeys = init_hostkeys();
1.234 djm 769: for (i = 0; i < num_user_hostfiles; i++)
770: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
771: for (i = 0; i < num_system_hostfiles; i++)
772: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 773: }
1.38 markus 774:
1.219 djm 775: retry:
1.229 djm 776: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 777: want_cert = sshkey_is_cert(host_key);
778: type = sshkey_type(host_key);
1.219 djm 779:
1.46 markus 780: /*
1.170 djm 781: * Check if the host key is present in the user's list of known
1.40 markus 782: * hosts or in the systemwide list.
783: */
1.229 djm 784: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
785: &host_found);
786:
1.40 markus 787: /*
788: * Also perform check for the ip address, skip the check if we are
1.219 djm 789: * localhost, looking for a certificate, or the hostname was an ip
790: * address to begin with.
1.40 markus 791: */
1.229 djm 792: if (!want_cert && ip_hostkeys != NULL) {
793: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
794: &ip_found);
1.38 markus 795: if (host_status == HOST_CHANGED &&
1.229 djm 796: (ip_status != HOST_CHANGED ||
797: (ip_found != NULL &&
1.280 markus 798: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 799: host_ip_differ = 1;
800: } else
801: ip_status = host_status;
802:
803: switch (host_status) {
804: case HOST_OK:
805: /* The host is known and the key matches. */
1.219 djm 806: debug("Host '%.200s' is known and matches the %s host %s.",
807: host, type, want_cert ? "certificate" : "key");
1.229 djm 808: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
809: host_found->file, host_found->line);
1.281 djm 810: if (want_cert &&
811: !check_host_cert(options.host_key_alias == NULL ?
812: hostname : options.host_key_alias, host_key))
1.219 djm 813: goto fail;
1.88 markus 814: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 815: if (readonly || want_cert)
1.138 itojun 816: logit("%s host key for IP address "
1.108 markus 817: "'%.128s' not in list of known hosts.",
818: type, ip);
1.234 djm 819: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 820: host_key, options.hash_known_hosts))
1.138 itojun 821: logit("Failed to add the %s host key for IP "
1.108 markus 822: "address '%.128s' to the list of known "
1.262 dtucker 823: "hosts (%.500s).", type, ip,
1.234 djm 824: user_hostfiles[0]);
1.88 markus 825: else
1.138 itojun 826: logit("Warning: Permanently added the %s host "
1.108 markus 827: "key for IP address '%.128s' to the list "
828: "of known hosts.", type, ip);
1.209 grunk 829: } else if (options.visual_host_key) {
1.259 djm 830: fp = sshkey_fingerprint(host_key,
1.254 djm 831: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 832: ra = sshkey_fingerprint(host_key,
1.254 djm 833: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 834: if (fp == NULL || ra == NULL)
835: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 836: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 837: free(ra);
838: free(fp);
1.38 markus 839: }
1.284 ! djm 840: if (options.verify_host_key_dns &&
! 841: options.strict_host_key_checking &&
! 842: !matching_host_key_dns) {
! 843: snprintf(msg, sizeof(msg),
! 844: "Are you sure you want to continue connecting "
! 845: "(yes/no)? ");
! 846: if (!confirm(msg))
! 847: goto fail;
! 848: msg[0] = '\0';
! 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. */
866: if (options.strict_host_key_checking == 1) {
1.108 markus 867: /*
868: * User has requested strict host key checking. We
869: * will not add the host key automatically. The only
870: * alternative left is to abort.
871: */
872: error("No %s host key is known for %.200s and you "
873: "have requested strict checking.", type, host);
874: goto fail;
1.38 markus 875: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 876: char msg1[1024], msg2[1024];
877:
1.229 djm 878: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 879: snprintf(msg1, sizeof(msg1),
1.168 djm 880: "\nbut keys of different type are already"
881: " known for this host.");
1.145 jakob 882: else
883: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 884: /* The default */
1.259 djm 885: fp = sshkey_fingerprint(host_key,
1.254 djm 886: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 887: ra = sshkey_fingerprint(host_key,
1.254 djm 888: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 889: if (fp == NULL || ra == NULL)
890: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 891: msg2[0] = '\0';
892: if (options.verify_host_key_dns) {
1.153 jakob 893: if (matching_host_key_dns)
1.145 jakob 894: snprintf(msg2, sizeof(msg2),
895: "Matching host key fingerprint"
896: " found in DNS.\n");
897: else
898: snprintf(msg2, sizeof(msg2),
899: "No matching host key fingerprint"
900: " found in DNS.\n");
901: }
1.119 markus 902: snprintf(msg, sizeof(msg),
1.108 markus 903: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 904: "established%s\n"
1.209 grunk 905: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 906: "Are you sure you want to continue connecting "
1.132 markus 907: "(yes/no)? ",
1.209 grunk 908: host, ip, msg1, type, fp,
909: options.visual_host_key ? "\n" : "",
910: options.visual_host_key ? ra : "",
911: msg2);
1.238 djm 912: free(ra);
913: free(fp);
1.119 markus 914: if (!confirm(msg))
1.108 markus 915: goto fail;
1.257 djm 916: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 917: }
1.161 djm 918: /*
919: * If not in strict mode, add the key automatically to the
920: * local known_hosts file.
921: */
1.88 markus 922: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 923: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 924: hostp = hostline;
1.161 djm 925: if (options.hash_known_hosts) {
926: /* Add hash of host and IP separately */
1.234 djm 927: r = add_host_to_hostfile(user_hostfiles[0],
928: host, host_key, options.hash_known_hosts) &&
929: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 930: host_key, options.hash_known_hosts);
931: } else {
932: /* Add unhashed "host,ip" */
1.234 djm 933: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 934: hostline, host_key,
935: options.hash_known_hosts);
936: }
937: } else {
1.234 djm 938: r = add_host_to_hostfile(user_hostfiles[0], host,
939: host_key, options.hash_known_hosts);
1.38 markus 940: hostp = host;
1.161 djm 941: }
1.38 markus 942:
1.161 djm 943: if (!r)
1.138 itojun 944: logit("Failed to add the host to the list of known "
1.234 djm 945: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 946: else
1.138 itojun 947: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 948: "list of known hosts.", hostp, type);
1.38 markus 949: break;
1.220 djm 950: case HOST_REVOKED:
951: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
952: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
953: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
954: error("The %s host key for %s is marked as revoked.", type, host);
955: error("This could mean that a stolen key is being used to");
956: error("impersonate this host.");
957:
958: /*
959: * If strict host key checking is in use, the user will have
960: * to edit the key manually and we can only abort.
961: */
962: if (options.strict_host_key_checking) {
963: error("%s host key for %.200s was revoked and you have "
964: "requested strict checking.", type, host);
965: goto fail;
966: }
967: goto continue_unsafe;
968:
1.38 markus 969: case HOST_CHANGED:
1.219 djm 970: if (want_cert) {
971: /*
972: * This is only a debug() since it is valid to have
973: * CAs with wildcard DNS matches that don't match
974: * all hosts that one might visit.
975: */
976: debug("Host certificate authority does not "
1.229 djm 977: "match %s in %s:%lu", CA_MARKER,
978: host_found->file, host_found->line);
1.219 djm 979: goto fail;
980: }
1.197 dtucker 981: if (readonly == ROQUIET)
982: goto fail;
1.38 markus 983: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 984: char *key_msg;
1.38 markus 985: if (ip_status == HOST_NEW)
1.158 avsm 986: key_msg = "is unknown";
1.38 markus 987: else if (ip_status == HOST_OK)
1.158 avsm 988: key_msg = "is unchanged";
1.38 markus 989: else
1.158 avsm 990: key_msg = "has a different value";
1.38 markus 991: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
992: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
993: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 994: error("The %s host key for %s has changed,", type, host);
1.208 ian 995: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 996: error("%s. This could either mean that", key_msg);
1.38 markus 997: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 998: error("and its host key have changed at the same time.");
1.88 markus 999: if (ip_status != HOST_NEW)
1.229 djm 1000: error("Offending key for IP in %s:%lu",
1001: ip_found->file, ip_found->line);
1.38 markus 1002: }
1003: /* The host key has changed. */
1.150 jakob 1004: warn_changed_key(host_key);
1.38 markus 1005: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 1006: user_hostfiles[0]);
1.280 markus 1007: error("Offending %s key in %s:%lu",
1008: sshkey_type(host_found->key),
1.229 djm 1009: host_found->file, host_found->line);
1.38 markus 1010:
1.40 markus 1011: /*
1012: * If strict host key checking is in use, the user will have
1013: * to edit the key manually and we can only abort.
1014: */
1.108 markus 1015: if (options.strict_host_key_checking) {
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: }
1.88 markus 1102: if (options.strict_host_key_checking == 1) {
1.143 djm 1103: logit("%s", msg);
1.108 markus 1104: error("Exiting, you have requested strict checking.");
1105: goto fail;
1.88 markus 1106: } else if (options.strict_host_key_checking == 2) {
1.119 markus 1107: strlcat(msg, "\nAre you sure you want "
1108: "to continue connecting (yes/no)? ", sizeof(msg));
1109: if (!confirm(msg))
1.108 markus 1110: goto fail;
1.119 markus 1111: } else {
1.143 djm 1112: logit("%s", msg);
1.88 markus 1113: }
1.257 djm 1114: }
1115:
1116: if (!hostkey_trusted && options.update_hostkeys) {
1117: debug("%s: hostkey not known or explicitly trusted: "
1118: "disabling UpdateHostkeys", __func__);
1119: options.update_hostkeys = 0;
1.38 markus 1120: }
1.82 provos 1121:
1.238 djm 1122: free(ip);
1123: free(host);
1.229 djm 1124: if (host_hostkeys != NULL)
1125: free_hostkeys(host_hostkeys);
1126: if (ip_hostkeys != NULL)
1127: free_hostkeys(ip_hostkeys);
1.108 markus 1128: return 0;
1129:
1130: fail:
1.220 djm 1131: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1132: /*
1133: * No matching certificate. Downgrade cert to raw key and
1134: * search normally.
1135: */
1136: debug("No matching CA found. Retry with plain key");
1.280 markus 1137: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1138: fatal("%s: sshkey_from_private: %s",
1139: __func__, ssh_err(r));
1140: if ((r = sshkey_drop_cert(raw_key)) != 0)
1141: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1142: host_key = raw_key;
1143: goto retry;
1144: }
1145: if (raw_key != NULL)
1.280 markus 1146: sshkey_free(raw_key);
1.238 djm 1147: free(ip);
1148: free(host);
1.229 djm 1149: if (host_hostkeys != NULL)
1150: free_hostkeys(host_hostkeys);
1151: if (ip_hostkeys != NULL)
1152: free_hostkeys(ip_hostkeys);
1.108 markus 1153: return -1;
1154: }
1155:
1.140 jakob 1156: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1157: int
1.279 markus 1158: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1159: {
1.267 djm 1160: u_int i;
1.250 djm 1161: int r = -1, flags = 0;
1.267 djm 1162: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1163: struct sshkey *plain = NULL;
1.229 djm 1164:
1.252 djm 1165: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1166: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1167: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1168: r = -1;
1169: goto out;
1170: }
1171:
1.267 djm 1172: if (sshkey_is_cert(host_key)) {
1173: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1174: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1175: error("%s: fingerprint CA key: %s",
1176: __func__, ssh_err(r));
1177: r = -1;
1178: goto out;
1179: }
1180: sshkey_format_cert_validity(host_key->cert,
1181: valid, sizeof(valid));
1182: debug("Server host certificate: %s %s, serial %llu "
1183: "ID \"%s\" CA %s %s valid %s",
1184: sshkey_ssh_name(host_key), fp,
1.269 djm 1185: (unsigned long long)host_key->cert->serial,
1186: host_key->cert->key_id,
1.267 djm 1187: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1188: valid);
1189: for (i = 0; i < host_key->cert->nprincipals; i++) {
1190: debug2("Server host certificate hostname: %s",
1191: host_key->cert->principals[i]);
1192: }
1193: } else {
1.276 djm 1194: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1195: }
1.252 djm 1196:
1197: if (sshkey_equal(previous_host_key, host_key)) {
1198: debug2("%s: server host key %s %s matches cached key",
1199: __func__, sshkey_type(host_key), fp);
1200: r = 0;
1201: goto out;
1202: }
1203:
1204: /* Check in RevokedHostKeys file if specified */
1205: if (options.revoked_host_keys != NULL) {
1206: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1207: switch (r) {
1208: case 0:
1209: break; /* not revoked */
1210: case SSH_ERR_KEY_REVOKED:
1211: error("Host key %s %s revoked by file %s",
1212: sshkey_type(host_key), fp,
1213: options.revoked_host_keys);
1214: r = -1;
1215: goto out;
1216: default:
1217: error("Error checking host key %s %s in "
1218: "revoked keys file %s: %s", sshkey_type(host_key),
1219: fp, options.revoked_host_keys, ssh_err(r));
1220: r = -1;
1221: goto out;
1222: }
1.250 djm 1223: }
1224:
1.247 djm 1225: if (options.verify_host_key_dns) {
1226: /*
1227: * XXX certs are not yet supported for DNS, so downgrade
1228: * them and try the plain key.
1229: */
1.252 djm 1230: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1231: goto out;
1232: if (sshkey_is_cert(plain))
1233: sshkey_drop_cert(plain);
1.247 djm 1234: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1235: if (flags & DNS_VERIFY_FOUND) {
1236: if (options.verify_host_key_dns == 1 &&
1237: flags & DNS_VERIFY_MATCH &&
1238: flags & DNS_VERIFY_SECURE) {
1.250 djm 1239: r = 0;
1.252 djm 1240: goto out;
1.247 djm 1241: }
1242: if (flags & DNS_VERIFY_MATCH) {
1243: matching_host_key_dns = 1;
1244: } else {
1.284 ! djm 1245: if (flags & DNS_VERIFY_MISSING) {
! 1246: warn_missing_key(plain);
! 1247: error("Add this host key to "
! 1248: "the SSHFP RR in DNS to get rid "
! 1249: "of this message.");
! 1250: } else {
! 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.");
! 1255: }
1.247 djm 1256: }
1.153 jakob 1257: }
1.140 jakob 1258: }
1259: }
1.250 djm 1260: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1261: options.user_hostfiles, options.num_user_hostfiles,
1262: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1263:
1.252 djm 1264: out:
1265: sshkey_free(plain);
1266: free(fp);
1.267 djm 1267: free(cafp);
1.250 djm 1268: if (r == 0 && host_key != NULL) {
1.280 markus 1269: sshkey_free(previous_host_key);
1270: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1271: }
1272:
1273: return r;
1.51 markus 1274: }
1.70 markus 1275:
1.51 markus 1276: /*
1277: * Starts a dialog with the server, and authenticates the current user on the
1278: * server. This does not need any extra privileges. The basic connection
1279: * to the server must already have been established before this is called.
1280: * If login fails, this function prints an error and never returns.
1281: * This function does not require super-user privileges.
1282: */
1283: void
1.120 markus 1284: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1285: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1286: {
1.241 djm 1287: char *host;
1.70 markus 1288: char *server_user, *local_user;
1289:
1290: local_user = xstrdup(pw->pw_name);
1291: server_user = options.user ? options.user : local_user;
1.51 markus 1292:
1293: /* Convert the user-supplied hostname into all lowercase. */
1294: host = xstrdup(orighost);
1.241 djm 1295: lowercase(host);
1.51 markus 1296:
1297: /* Exchange protocol version identification strings with the server. */
1.202 djm 1298: ssh_exchange_identification(timeout_ms);
1.51 markus 1299:
1300: /* Put the connection into non-blocking mode. */
1301: packet_set_nonblocking();
1302:
1303: /* key exchange */
1304: /* authenticate user */
1.261 dtucker 1305: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.276 djm 1306: ssh_kex2(host, hostaddr, port);
1307: ssh_userauth2(local_user, server_user, host, sensitive);
1.238 djm 1308: free(local_user);
1.97 markus 1309: }
1310:
1311: void
1312: ssh_put_password(char *password)
1313: {
1314: int size;
1315: char *padded;
1316:
1.99 deraadt 1317: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1318: packet_put_cstring(password);
1.99 deraadt 1319: return;
1320: }
1.272 deraadt 1321: size = ROUNDUP(strlen(password) + 1, 32);
1.179 djm 1322: padded = xcalloc(1, size);
1.97 markus 1323: strlcpy(padded, password, size);
1324: packet_put_string(padded, size);
1.245 djm 1325: explicit_bzero(padded, size);
1.238 djm 1326: free(padded);
1.132 markus 1327: }
1328:
1329: /* print all known host keys for a given host, but skip keys of given type */
1330: static int
1.279 markus 1331: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1332: {
1.242 djm 1333: int type[] = {
1334: KEY_RSA,
1335: KEY_DSA,
1336: KEY_ECDSA,
1337: KEY_ED25519,
1338: -1
1339: };
1.229 djm 1340: int i, ret = 0;
1341: char *fp, *ra;
1342: const struct hostkey_entry *found;
1.132 markus 1343:
1344: for (i = 0; type[i] != -1; i++) {
1345: if (type[i] == key->type)
1346: continue;
1.229 djm 1347: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1348: continue;
1.259 djm 1349: fp = sshkey_fingerprint(found->key,
1.254 djm 1350: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1351: ra = sshkey_fingerprint(found->key,
1.254 djm 1352: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1353: if (fp == NULL || ra == NULL)
1354: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1355: logit("WARNING: %s key found for host %s\n"
1356: "in %s:%lu\n"
1357: "%s key fingerprint %s.",
1358: key_type(found->key),
1359: found->host, found->file, found->line,
1360: key_type(found->key), fp);
1361: if (options.visual_host_key)
1362: logit("%s", ra);
1.238 djm 1363: free(ra);
1364: free(fp);
1.229 djm 1365: ret = 1;
1.132 markus 1366: }
1.229 djm 1367: return ret;
1.150 jakob 1368: }
1369:
1370: static void
1.279 markus 1371: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1372: {
1373: char *fp;
1374:
1.259 djm 1375: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1376: SSH_FP_DEFAULT);
1.259 djm 1377: if (fp == NULL)
1378: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1379:
1380: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1381: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1382: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1383: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1384: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1385: error("It is also possible that a host key has just been changed.");
1.150 jakob 1386: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.284 ! djm 1387: sshkey_type(host_key), fp);
1.150 jakob 1388: error("Please contact your system administrator.");
1389:
1.238 djm 1390: free(fp);
1.171 reyk 1391: }
1392:
1.284 ! djm 1393: static void
! 1394: warn_missing_key(struct sshkey *host_key)
! 1395: {
! 1396: char *fp;
! 1397:
! 1398: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
! 1399: SSH_FP_DEFAULT);
! 1400: if (fp == NULL)
! 1401: fatal("%s: sshkey_fingerprint fail", __func__);
! 1402:
! 1403: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
! 1404: error("@ WARNING: REMOTE HOST IDENTIFICATION IS MISSING @");
! 1405: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
! 1406: error("The fingerprint for the %s key sent by the remote host is\n%s.",
! 1407: sshkey_type(host_key), fp);
! 1408: error("Please contact your system administrator.");
! 1409:
! 1410: free(fp);
! 1411: }
1.171 reyk 1412: /*
1413: * Execute a local command
1414: */
1415: int
1416: ssh_local_cmd(const char *args)
1417: {
1418: char *shell;
1419: pid_t pid;
1420: int status;
1.231 djm 1421: void (*osighand)(int);
1.171 reyk 1422:
1423: if (!options.permit_local_command ||
1424: args == NULL || !*args)
1425: return (1);
1426:
1.226 djm 1427: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1428: shell = _PATH_BSHELL;
1429:
1.231 djm 1430: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1431: pid = fork();
1432: if (pid == 0) {
1.232 djm 1433: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1434: debug3("Executing %s -c \"%s\"", shell, args);
1435: execl(shell, shell, "-c", args, (char *)NULL);
1436: error("Couldn't execute %s -c \"%s\": %s",
1437: shell, args, strerror(errno));
1438: _exit(1);
1439: } else if (pid == -1)
1440: fatal("fork failed: %.100s", strerror(errno));
1441: while (waitpid(pid, &status, 0) == -1)
1442: if (errno != EINTR)
1443: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1444: signal(SIGCHLD, osighand);
1.171 reyk 1445:
1446: if (!WIFEXITED(status))
1447: return (1);
1448:
1449: return (WEXITSTATUS(status));
1.266 jcs 1450: }
1451:
1452: void
1.279 markus 1453: maybe_add_key_to_agent(char *authfile, struct sshkey *private, char *comment,
1.266 jcs 1454: char *passphrase)
1455: {
1456: int auth_sock = -1, r;
1457:
1458: if (options.add_keys_to_agent == 0)
1459: return;
1460:
1461: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1462: debug3("no authentication agent, not adding key");
1463: return;
1464: }
1465:
1466: if (options.add_keys_to_agent == 2 &&
1467: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1468: debug3("user denied adding this key");
1.273 dtucker 1469: close(auth_sock);
1.266 jcs 1470: return;
1471: }
1472:
1473: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1474: (options.add_keys_to_agent == 3))) == 0)
1475: debug("identity added to agent: %s", authfile);
1476: else
1477: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1478: close(auth_sock);
1.1 deraadt 1479: }
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