Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.283
1.283 ! djm 1: /* $OpenBSD: sshconnect.c,v 1.282 2017/06/24 05:37:44 djm Exp $ */
1.1 deraadt 2: /*
1.39 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
1.78 deraadt 8: *
9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 14: */
1.1 deraadt 15:
1.174 stevesk 16: #include <sys/types.h>
17: #include <sys/wait.h>
1.175 stevesk 18: #include <sys/stat.h>
1.187 stevesk 19: #include <sys/socket.h>
1.195 stevesk 20: #include <sys/time.h>
1.187 stevesk 21:
22: #include <netinet/in.h>
1.172 stevesk 23:
1.176 stevesk 24: #include <ctype.h>
1.190 stevesk 25: #include <errno.h>
1.216 dtucker 26: #include <fcntl.h>
1.191 stevesk 27: #include <netdb.h>
1.172 stevesk 28: #include <paths.h>
1.282 djm 29: #include <poll.h>
1.199 deraadt 30: #include <signal.h>
1.188 stevesk 31: #include <pwd.h>
1.198 stevesk 32: #include <stdio.h>
1.196 stevesk 33: #include <stdlib.h>
1.193 stevesk 34: #include <string.h>
1.192 stevesk 35: #include <unistd.h>
1.71 markus 36:
1.199 deraadt 37: #include "xmalloc.h"
1.91 markus 38: #include "ssh.h"
1.59 markus 39: #include "buffer.h"
1.1 deraadt 40: #include "packet.h"
41: #include "uidswap.h"
1.21 markus 42: #include "compat.h"
1.58 markus 43: #include "key.h"
1.71 markus 44: #include "sshconnect.h"
1.58 markus 45: #include "hostfile.h"
1.91 markus 46: #include "log.h"
1.251 millert 47: #include "misc.h"
1.91 markus 48: #include "readconf.h"
49: #include "atomicio.h"
1.140 jakob 50: #include "dns.h"
1.239 djm 51: #include "monitor_fdpass.h"
1.219 djm 52: #include "ssh2.h"
1.186 stevesk 53: #include "version.h"
1.252 djm 54: #include "authfile.h"
55: #include "ssherr.h"
1.266 jcs 56: #include "authfd.h"
1.140 jakob 57:
1.70 markus 58: char *client_version_string = NULL;
59: char *server_version_string = NULL;
1.279 markus 60: struct sshkey *previous_host_key = NULL;
1.59 markus 61:
1.169 stevesk 62: static int matching_host_key_dns = 0;
1.145 jakob 63:
1.227 djm 64: static pid_t proxy_command_pid = 0;
65:
1.124 markus 66: /* import */
1.43 markus 67: extern Options options;
1.50 markus 68: extern char *__progname;
1.124 markus 69: extern uid_t original_real_uid;
70: extern uid_t original_effective_uid;
1.91 markus 71:
1.279 markus 72: static int show_other_keys(struct hostkeys *, struct sshkey *);
73: static void warn_changed_key(struct sshkey *);
1.132 markus 74:
1.239 djm 75: /* Expand a proxy command */
76: static char *
77: expand_proxy_command(const char *proxy_command, const char *user,
78: const char *host, int port)
79: {
80: char *tmp, *ret, strport[NI_MAXSERV];
81:
1.241 djm 82: snprintf(strport, sizeof strport, "%d", port);
1.239 djm 83: xasprintf(&tmp, "exec %s", proxy_command);
84: ret = percent_expand(tmp, "h", host, "p", strport,
85: "r", options.user, (char *)NULL);
86: free(tmp);
87: return ret;
88: }
89:
90: /*
91: * Connect to the given ssh server using a proxy command that passes a
92: * a connected fd back to us.
93: */
94: static int
95: ssh_proxy_fdpass_connect(const char *host, u_short port,
96: const char *proxy_command)
97: {
98: char *command_string;
99: int sp[2], sock;
100: pid_t pid;
101: char *shell;
102:
103: if ((shell = getenv("SHELL")) == NULL)
104: shell = _PATH_BSHELL;
105:
106: if (socketpair(AF_UNIX, SOCK_STREAM, 0, sp) < 0)
107: fatal("Could not create socketpair to communicate with "
108: "proxy dialer: %.100s", strerror(errno));
109:
110: command_string = expand_proxy_command(proxy_command, options.user,
111: host, port);
112: debug("Executing proxy dialer command: %.500s", command_string);
113:
114: /* Fork and execute the proxy command. */
115: if ((pid = fork()) == 0) {
116: char *argv[10];
117:
118: /* Child. Permanently give up superuser privileges. */
119: permanently_drop_suid(original_real_uid);
120:
121: close(sp[1]);
122: /* Redirect stdin and stdout. */
123: if (sp[0] != 0) {
124: if (dup2(sp[0], 0) < 0)
125: perror("dup2 stdin");
126: }
127: if (sp[0] != 1) {
128: if (dup2(sp[0], 1) < 0)
129: perror("dup2 stdout");
130: }
131: if (sp[0] >= 2)
132: close(sp[0]);
133:
134: /*
135: * Stderr is left as it is so that error messages get
136: * printed on the user's terminal.
137: */
138: argv[0] = shell;
139: argv[1] = "-c";
140: argv[2] = command_string;
141: argv[3] = NULL;
142:
143: /*
144: * Execute the proxy command.
145: * Note that we gave up any extra privileges above.
146: */
147: execv(argv[0], argv);
148: perror(argv[0]);
149: exit(1);
150: }
151: /* Parent. */
152: if (pid < 0)
153: fatal("fork failed: %.100s", strerror(errno));
154: close(sp[0]);
155: free(command_string);
156:
157: if ((sock = mm_receive_fd(sp[1])) == -1)
158: fatal("proxy dialer did not pass back a connection");
1.271 markus 159: close(sp[1]);
1.239 djm 160:
161: while (waitpid(pid, NULL, 0) == -1)
162: if (errno != EINTR)
163: fatal("Couldn't wait for child: %s", strerror(errno));
164:
165: /* Set the connection file descriptors. */
166: packet_set_connection(sock, sock);
167:
168: return 0;
169: }
170:
1.39 deraadt 171: /*
172: * Connect to the given ssh server using a proxy command.
173: */
1.109 itojun 174: static int
1.124 markus 175: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 176: {
1.239 djm 177: char *command_string;
1.38 markus 178: int pin[2], pout[2];
1.69 deraadt 179: pid_t pid;
1.239 djm 180: char *shell;
1.237 markus 181:
1.226 djm 182: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.201 djm 183: shell = _PATH_BSHELL;
1.38 markus 184:
185: /* Create pipes for communicating with the proxy. */
186: if (pipe(pin) < 0 || pipe(pout) < 0)
187: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 188: strerror(errno));
1.38 markus 189:
1.239 djm 190: command_string = expand_proxy_command(proxy_command, options.user,
191: host, port);
1.38 markus 192: debug("Executing proxy command: %.500s", command_string);
193:
194: /* Fork and execute the proxy command. */
195: if ((pid = fork()) == 0) {
196: char *argv[10];
197:
198: /* Child. Permanently give up superuser privileges. */
1.184 markus 199: permanently_drop_suid(original_real_uid);
1.38 markus 200:
201: /* Redirect stdin and stdout. */
202: close(pin[1]);
203: if (pin[0] != 0) {
204: if (dup2(pin[0], 0) < 0)
205: perror("dup2 stdin");
206: close(pin[0]);
207: }
208: close(pout[0]);
209: if (dup2(pout[1], 1) < 0)
210: perror("dup2 stdout");
211: /* Cannot be 1 because pin allocated two descriptors. */
212: close(pout[1]);
213:
214: /* Stderr is left as it is so that error messages get
215: printed on the user's terminal. */
1.201 djm 216: argv[0] = shell;
1.38 markus 217: argv[1] = "-c";
218: argv[2] = command_string;
219: argv[3] = NULL;
220:
221: /* Execute the proxy command. Note that we gave up any
222: extra privileges above. */
1.232 djm 223: signal(SIGPIPE, SIG_DFL);
1.89 markus 224: execv(argv[0], argv);
225: perror(argv[0]);
1.38 markus 226: exit(1);
227: }
228: /* Parent. */
229: if (pid < 0)
230: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 231: else
232: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 233:
234: /* Close child side of the descriptors. */
235: close(pin[0]);
236: close(pout[1]);
237:
238: /* Free the command name. */
1.238 djm 239: free(command_string);
1.38 markus 240:
241: /* Set the connection file descriptors. */
242: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 243:
1.110 markus 244: /* Indicate OK return */
245: return 0;
1.227 djm 246: }
247:
248: void
249: ssh_kill_proxy_command(void)
250: {
251: /*
252: * Send SIGHUP to proxy command if used. We don't wait() in
253: * case it hangs and instead rely on init to reap the child
254: */
255: if (proxy_command_pid > 1)
1.228 djm 256: kill(proxy_command_pid, SIGHUP);
1.1 deraadt 257: }
258:
1.39 deraadt 259: /*
260: * Creates a (possibly privileged) socket for use as the ssh connection.
261: */
1.109 itojun 262: static int
1.139 markus 263: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 264: {
1.240 djm 265: int sock, r, gaierr;
1.246 djm 266: struct addrinfo hints, *res = NULL;
1.1 deraadt 267:
1.217 dtucker 268: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.216 dtucker 269: if (sock < 0) {
1.240 djm 270: error("socket: %s", strerror(errno));
1.216 dtucker 271: return -1;
272: }
273: fcntl(sock, F_SETFD, FD_CLOEXEC);
1.105 markus 274:
275: /* Bind the socket to an alternative local IP address */
1.240 djm 276: if (options.bind_address == NULL && !privileged)
1.105 markus 277: return sock;
278:
1.246 djm 279: if (options.bind_address) {
280: memset(&hints, 0, sizeof(hints));
281: hints.ai_family = ai->ai_family;
282: hints.ai_socktype = ai->ai_socktype;
283: hints.ai_protocol = ai->ai_protocol;
284: hints.ai_flags = AI_PASSIVE;
285: gaierr = getaddrinfo(options.bind_address, NULL, &hints, &res);
286: if (gaierr) {
287: error("getaddrinfo: %s: %s", options.bind_address,
288: ssh_gai_strerror(gaierr));
289: close(sock);
290: return -1;
291: }
1.105 markus 292: }
1.240 djm 293: /*
294: * If we are running as root and want to connect to a privileged
295: * port, bind our own socket to a privileged port.
296: */
297: if (privileged) {
298: PRIV_START;
1.246 djm 299: r = bindresvport_sa(sock, res ? res->ai_addr : NULL);
1.240 djm 300: PRIV_END;
301: if (r < 0) {
302: error("bindresvport_sa: af=%d %s", ai->ai_family,
303: strerror(errno));
304: goto fail;
305: }
306: } else {
307: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
308: error("bind: %s: %s", options.bind_address,
309: strerror(errno));
310: fail:
311: close(sock);
312: freeaddrinfo(res);
313: return -1;
314: }
1.38 markus 315: }
1.246 djm 316: if (res != NULL)
317: freeaddrinfo(res);
1.38 markus 318: return sock;
1.1 deraadt 319: }
320:
1.282 djm 321: /*
322: * Wait up to *timeoutp milliseconds for fd to be readable. Updates
323: * *timeoutp with time remaining.
324: * Returns 0 if fd ready or -1 on timeout or error (see errno).
325: */
326: static int
327: waitrfd(int fd, int *timeoutp)
328: {
329: struct pollfd pfd;
330: struct timeval t_start;
331: int oerrno, r;
332:
333: gettimeofday(&t_start, NULL);
334: pfd.fd = fd;
335: pfd.events = POLLIN;
336: for (; *timeoutp >= 0;) {
337: r = poll(&pfd, 1, *timeoutp);
338: oerrno = errno;
339: ms_subtract_diff(&t_start, timeoutp);
340: errno = oerrno;
341: if (r > 0)
342: return 0;
343: else if (r == -1 && errno != EAGAIN)
344: return -1;
345: else if (r == 0)
346: break;
347: }
348: /* timeout */
349: errno = ETIMEDOUT;
350: return -1;
351: }
352:
1.141 djm 353: static int
354: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
1.202 djm 355: socklen_t addrlen, int *timeoutp)
1.141 djm 356: {
1.282 djm 357: int optval = 0;
358: socklen_t optlen = sizeof(optval);
1.141 djm 359:
1.282 djm 360: /* No timeout: just do a blocking connect() */
361: if (*timeoutp <= 0)
362: return connect(sockfd, serv_addr, addrlen);
1.141 djm 363:
1.156 djm 364: set_nonblock(sockfd);
1.282 djm 365: if (connect(sockfd, serv_addr, addrlen) == 0) {
366: /* Succeeded already? */
1.156 djm 367: unset_nonblock(sockfd);
1.282 djm 368: return 0;
369: } else if (errno != EINPROGRESS)
370: return -1;
371:
372: if (waitrfd(sockfd, timeoutp) == -1)
373: return -1;
1.141 djm 374:
1.282 djm 375: /* Completed or failed */
376: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval, &optlen) == -1) {
377: debug("getsockopt: %s", strerror(errno));
378: return -1;
1.141 djm 379: }
1.282 djm 380: if (optval != 0) {
381: errno = optval;
382: return -1;
1.202 djm 383: }
1.282 djm 384: unset_nonblock(sockfd);
385: return 0;
1.141 djm 386: }
387:
1.39 deraadt 388: /*
1.49 markus 389: * Opens a TCP/IP connection to the remote server on the given host.
390: * The address of the remote host will be returned in hostaddr.
1.124 markus 391: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 392: * a privileged port will be allocated to make the connection.
1.124 markus 393: * This requires super-user privileges if needpriv is true.
1.39 deraadt 394: * Connection_attempts specifies the maximum number of tries (one per
395: * second). If proxy_command is non-NULL, it specifies the command (with %h
396: * and %p substituted for host and port, respectively) to use to contact
397: * the daemon.
398: */
1.241 djm 399: static int
400: ssh_connect_direct(const char *host, struct addrinfo *aitop,
401: struct sockaddr_storage *hostaddr, u_short port, int family,
402: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
1.1 deraadt 403: {
1.90 markus 404: int on = 1;
1.49 markus 405: int sock = -1, attempt;
1.90 markus 406: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.241 djm 407: struct addrinfo *ai;
1.38 markus 408:
1.265 djm 409: debug2("%s: needpriv %d", __func__, needpriv);
1.268 djm 410: memset(ntop, 0, sizeof(ntop));
411: memset(strport, 0, sizeof(strport));
1.38 markus 412:
1.181 markus 413: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.200 markus 414: if (attempt > 0) {
415: /* Sleep a moment before retrying. */
416: sleep(1);
1.38 markus 417: debug("Trying again...");
1.200 markus 418: }
1.181 markus 419: /*
420: * Loop through addresses for this host, and try each one in
421: * sequence until the connection succeeds.
422: */
1.49 markus 423: for (ai = aitop; ai; ai = ai->ai_next) {
1.241 djm 424: if (ai->ai_family != AF_INET &&
425: ai->ai_family != AF_INET6)
1.49 markus 426: continue;
427: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
428: ntop, sizeof(ntop), strport, sizeof(strport),
429: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
1.265 djm 430: error("%s: getnameinfo failed", __func__);
1.49 markus 431: continue;
432: }
433: debug("Connecting to %.200s [%.100s] port %s.",
434: host, ntop, strport);
435:
436: /* Create a socket for connecting. */
1.139 markus 437: sock = ssh_create_socket(needpriv, ai);
1.49 markus 438: if (sock < 0)
1.110 markus 439: /* Any error is already output */
1.49 markus 440: continue;
441:
1.141 djm 442: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
1.202 djm 443: timeout_ms) >= 0) {
1.49 markus 444: /* Successful connection. */
1.102 markus 445: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 446: break;
1.49 markus 447: } else {
1.131 itojun 448: debug("connect to address %s port %s: %s",
449: ntop, strport, strerror(errno));
1.38 markus 450: close(sock);
1.181 markus 451: sock = -1;
1.38 markus 452: }
453: }
1.181 markus 454: if (sock != -1)
1.49 markus 455: break; /* Successful connection. */
1.38 markus 456: }
1.49 markus 457:
1.38 markus 458: /* Return failure if we didn't get a successful connection. */
1.181 markus 459: if (sock == -1) {
1.159 markus 460: error("ssh: connect to host %s port %s: %s",
1.130 itojun 461: host, strport, strerror(errno));
1.159 markus 462: return (-1);
1.130 itojun 463: }
1.38 markus 464:
465: debug("Connection established.");
1.90 markus 466:
1.155 markus 467: /* Set SO_KEEPALIVE if requested. */
1.202 djm 468: if (want_keepalive &&
1.90 markus 469: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
470: sizeof(on)) < 0)
471: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 472:
473: /* Set the connection. */
474: packet_set_connection(sock, sock);
1.1 deraadt 475:
1.110 markus 476: return 0;
1.59 markus 477: }
478:
1.241 djm 479: int
480: ssh_connect(const char *host, struct addrinfo *addrs,
481: struct sockaddr_storage *hostaddr, u_short port, int family,
482: int connection_attempts, int *timeout_ms, int want_keepalive, int needpriv)
483: {
484: if (options.proxy_command == NULL) {
485: return ssh_connect_direct(host, addrs, hostaddr, port, family,
486: connection_attempts, timeout_ms, want_keepalive, needpriv);
487: } else if (strcmp(options.proxy_command, "-") == 0) {
488: packet_set_connection(STDIN_FILENO, STDOUT_FILENO);
489: return 0; /* Always succeeds */
490: } else if (options.proxy_use_fdpass) {
491: return ssh_proxy_fdpass_connect(host, port,
492: options.proxy_command);
493: }
494: return ssh_proxy_connect(host, port, options.proxy_command);
495: }
496:
1.235 djm 497: static void
498: send_client_banner(int connection_out, int minor1)
499: {
500: /* Send our own protocol version identification. */
1.276 djm 501: xasprintf(&client_version_string, "SSH-%d.%d-%.100s\r\n",
502: PROTOCOL_MAJOR_2, PROTOCOL_MINOR_2, SSH_VERSION);
1.270 markus 503: if (atomicio(vwrite, connection_out, client_version_string,
1.235 djm 504: strlen(client_version_string)) != strlen(client_version_string))
505: fatal("write: %.100s", strerror(errno));
506: chop(client_version_string);
507: debug("Local version string %.100s", client_version_string);
508: }
509:
1.43 markus 510: /*
1.39 deraadt 511: * Waits for the server identification string, and sends our own
512: * identification string.
513: */
1.213 andreas 514: void
1.202 djm 515: ssh_exchange_identification(int timeout_ms)
1.1 deraadt 516: {
1.38 markus 517: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 518: int remote_major, remote_minor, mismatch;
1.38 markus 519: int connection_in = packet_get_connection_in();
520: int connection_out = packet_get_connection_out();
1.185 djm 521: u_int i, n;
1.202 djm 522: size_t len;
1.282 djm 523: int rc;
1.38 markus 524:
1.275 djm 525: send_client_banner(connection_out, 0);
1.235 djm 526:
1.163 avsm 527: /* Read other side's version identification. */
1.185 djm 528: for (n = 0;;) {
1.75 markus 529: for (i = 0; i < sizeof(buf) - 1; i++) {
1.202 djm 530: if (timeout_ms > 0) {
1.282 djm 531: rc = waitrfd(connection_in, &timeout_ms);
532: if (rc == -1 && errno == ETIMEDOUT) {
1.202 djm 533: fatal("Connection timed out during "
534: "banner exchange");
1.282 djm 535: } else if (rc == -1) {
536: fatal("%s: %s",
537: __func__, strerror(errno));
1.202 djm 538: }
539: }
540:
1.270 markus 541: len = atomicio(read, connection_in, &buf[i], 1);
1.167 djm 542: if (len != 1 && errno == EPIPE)
1.202 djm 543: fatal("ssh_exchange_identification: "
544: "Connection closed by remote host");
1.163 avsm 545: else if (len != 1)
1.202 djm 546: fatal("ssh_exchange_identification: "
547: "read: %.100s", strerror(errno));
1.75 markus 548: if (buf[i] == '\r') {
549: buf[i] = '\n';
550: buf[i + 1] = 0;
551: continue; /**XXX wait for \n */
552: }
553: if (buf[i] == '\n') {
554: buf[i + 1] = 0;
555: break;
556: }
1.185 djm 557: if (++n > 65536)
1.202 djm 558: fatal("ssh_exchange_identification: "
559: "No banner received");
1.38 markus 560: }
1.75 markus 561: buf[sizeof(buf) - 1] = 0;
1.76 markus 562: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 563: break;
1.75 markus 564: debug("ssh_exchange_identification: %s", buf);
1.38 markus 565: }
1.59 markus 566: server_version_string = xstrdup(buf);
1.38 markus 567:
1.40 markus 568: /*
569: * Check that the versions match. In future this might accept
570: * several versions and set appropriate flags to handle them.
571: */
1.59 markus 572: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
573: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 574: fatal("Bad remote protocol version identification: '%.100s'", buf);
575: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 576: remote_major, remote_minor, remote_version);
1.38 markus 577:
1.255 markus 578: active_state->compat = compat_datafellows(remote_version);
1.64 markus 579: mismatch = 0;
1.59 markus 580:
1.116 deraadt 581: switch (remote_major) {
1.276 djm 582: case 2:
583: break;
1.64 markus 584: case 1:
1.276 djm 585: if (remote_minor != 99)
1.64 markus 586: mismatch = 1;
587: break;
1.68 markus 588: default:
1.64 markus 589: mismatch = 1;
590: break;
1.38 markus 591: }
1.64 markus 592: if (mismatch)
1.38 markus 593: fatal("Protocol major versions differ: %d vs. %d",
1.275 djm 594: PROTOCOL_MAJOR_2, remote_major);
1.244 djm 595: if ((datafellows & SSH_BUG_DERIVEKEY) != 0)
596: fatal("Server version \"%.100s\" uses unsafe key agreement; "
597: "refusing connection", remote_version);
1.243 djm 598: if ((datafellows & SSH_BUG_RSASIGMD5) != 0)
599: logit("Server version \"%.100s\" uses unsafe RSA signature "
600: "scheme; disabling use of RSA keys", remote_version);
1.59 markus 601: chop(server_version_string);
1.1 deraadt 602: }
603:
1.96 markus 604: /* defaults to 'no' */
1.109 itojun 605: static int
1.112 markus 606: confirm(const char *prompt)
1.1 deraadt 607: {
1.119 markus 608: const char *msg, *again = "Please type 'yes' or 'no': ";
609: char *p;
610: int ret = -1;
1.96 markus 611:
612: if (options.batch_mode)
613: return 0;
1.119 markus 614: for (msg = prompt;;msg = again) {
615: p = read_passphrase(msg, RP_ECHO);
616: if (p == NULL ||
617: (p[0] == '\0') || (p[0] == '\n') ||
618: strncasecmp(p, "no", 2) == 0)
619: ret = 0;
1.127 markus 620: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 621: ret = 1;
1.238 djm 622: free(p);
1.119 markus 623: if (ret != -1)
624: return ret;
1.1 deraadt 625: }
626: }
627:
1.219 djm 628: static int
1.279 markus 629: check_host_cert(const char *host, const struct sshkey *host_key)
1.219 djm 630: {
631: const char *reason;
632:
633: if (key_cert_check_authority(host_key, 1, 0, host, &reason) != 0) {
634: error("%s", reason);
635: return 0;
636: }
1.249 djm 637: if (buffer_len(host_key->cert->critical) != 0) {
1.223 djm 638: error("Certificate for %s contains unsupported "
639: "critical options(s)", host);
1.219 djm 640: return 0;
641: }
642: return 1;
643: }
644:
1.229 djm 645: static int
646: sockaddr_is_local(struct sockaddr *hostaddr)
647: {
648: switch (hostaddr->sa_family) {
649: case AF_INET:
650: return (ntohl(((struct sockaddr_in *)hostaddr)->
651: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
652: case AF_INET6:
653: return IN6_IS_ADDR_LOOPBACK(
654: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
655: default:
656: return 0;
657: }
658: }
659:
660: /*
661: * Prepare the hostname and ip address strings that are used to lookup
662: * host keys in known_hosts files. These may have a port number appended.
663: */
664: void
665: get_hostfile_hostname_ipaddr(char *hostname, struct sockaddr *hostaddr,
666: u_short port, char **hostfile_hostname, char **hostfile_ipaddr)
667: {
668: char ntop[NI_MAXHOST];
669:
670: /*
671: * We don't have the remote ip-address for connections
672: * using a proxy command
673: */
674: if (hostfile_ipaddr != NULL) {
675: if (options.proxy_command == NULL) {
676: if (getnameinfo(hostaddr, hostaddr->sa_len,
677: ntop, sizeof(ntop), NULL, 0, NI_NUMERICHOST) != 0)
1.259 djm 678: fatal("%s: getnameinfo failed", __func__);
1.229 djm 679: *hostfile_ipaddr = put_host_port(ntop, port);
680: } else {
681: *hostfile_ipaddr = xstrdup("<no hostip for proxy "
682: "command>");
683: }
684: }
685:
686: /*
687: * Allow the user to record the key under a different name or
688: * differentiate a non-standard port. This is useful for ssh
689: * tunneling over forwarded connections or if you run multiple
690: * sshd's on different ports on the same machine.
691: */
692: if (hostfile_hostname != NULL) {
693: if (options.host_key_alias != NULL) {
694: *hostfile_hostname = xstrdup(options.host_key_alias);
695: debug("using hostkeyalias: %s", *hostfile_hostname);
696: } else {
697: *hostfile_hostname = put_host_port(hostname, port);
698: }
699: }
700: }
701:
1.39 deraadt 702: /*
1.108 markus 703: * check whether the supplied host key is valid, return -1 if the key
1.234 djm 704: * is not valid. user_hostfile[0] will not be updated if 'readonly' is true.
1.39 deraadt 705: */
1.197 dtucker 706: #define RDRW 0
707: #define RDONLY 1
708: #define ROQUIET 2
1.109 itojun 709: static int
1.197 dtucker 710: check_host_key(char *hostname, struct sockaddr *hostaddr, u_short port,
1.279 markus 711: struct sshkey *host_key, int readonly,
1.234 djm 712: char **user_hostfiles, u_int num_user_hostfiles,
713: char **system_hostfiles, u_int num_system_hostfiles)
1.1 deraadt 714: {
1.234 djm 715: HostStatus host_status;
716: HostStatus ip_status;
1.279 markus 717: struct sshkey *raw_key = NULL;
1.189 dtucker 718: char *ip = NULL, *host = NULL;
1.204 grunk 719: char hostline[1000], *hostp, *fp, *ra;
1.119 markus 720: char msg[1024];
1.234 djm 721: const char *type;
722: const struct hostkey_entry *host_found, *ip_found;
1.229 djm 723: int len, cancelled_forwarding = 0;
1.234 djm 724: int local = sockaddr_is_local(hostaddr);
1.280 markus 725: int r, want_cert = sshkey_is_cert(host_key), host_ip_differ = 0;
1.257 djm 726: int hostkey_trusted = 0; /* Known or explicitly accepted by user */
1.229 djm 727: struct hostkeys *host_hostkeys, *ip_hostkeys;
1.234 djm 728: u_int i;
1.49 markus 729:
730: /*
731: * Force accepting of the host key for loopback/localhost. The
732: * problem is that if the home directory is NFS-mounted to multiple
733: * machines, localhost will refer to a different machine in each of
734: * them, and the user will get bogus HOST_CHANGED warnings. This
735: * essentially disables host authentication for localhost; however,
736: * this is probably not a real problem.
737: */
1.111 markus 738: if (options.no_host_authentication_for_localhost == 1 && local &&
739: options.host_key_alias == NULL) {
1.88 markus 740: debug("Forcing accepting of host key for "
741: "loopback/localhost.");
1.108 markus 742: return 0;
1.49 markus 743: }
1.42 markus 744:
745: /*
1.229 djm 746: * Prepare the hostname and address strings used for hostkey lookup.
747: * In some cases, these will have a port number appended.
1.42 markus 748: */
1.229 djm 749: get_hostfile_hostname_ipaddr(hostname, hostaddr, port, &host, &ip);
1.206 grunk 750:
751: /*
1.88 markus 752: * Turn off check_host_ip if the connection is to localhost, via proxy
753: * command or if we don't have a hostname to compare with
754: */
1.189 dtucker 755: if (options.check_host_ip && (local ||
756: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 757: options.check_host_ip = 0;
1.86 markus 758:
1.229 djm 759: host_hostkeys = init_hostkeys();
1.234 djm 760: for (i = 0; i < num_user_hostfiles; i++)
761: load_hostkeys(host_hostkeys, host, user_hostfiles[i]);
762: for (i = 0; i < num_system_hostfiles; i++)
763: load_hostkeys(host_hostkeys, host, system_hostfiles[i]);
1.229 djm 764:
765: ip_hostkeys = NULL;
766: if (!want_cert && options.check_host_ip) {
767: ip_hostkeys = init_hostkeys();
1.234 djm 768: for (i = 0; i < num_user_hostfiles; i++)
769: load_hostkeys(ip_hostkeys, ip, user_hostfiles[i]);
770: for (i = 0; i < num_system_hostfiles; i++)
771: load_hostkeys(ip_hostkeys, ip, system_hostfiles[i]);
1.84 markus 772: }
1.38 markus 773:
1.219 djm 774: retry:
1.229 djm 775: /* Reload these as they may have changed on cert->key downgrade */
1.280 markus 776: want_cert = sshkey_is_cert(host_key);
777: type = sshkey_type(host_key);
1.219 djm 778:
1.46 markus 779: /*
1.170 djm 780: * Check if the host key is present in the user's list of known
1.40 markus 781: * hosts or in the systemwide list.
782: */
1.229 djm 783: host_status = check_key_in_hostkeys(host_hostkeys, host_key,
784: &host_found);
785:
1.40 markus 786: /*
787: * Also perform check for the ip address, skip the check if we are
1.219 djm 788: * localhost, looking for a certificate, or the hostname was an ip
789: * address to begin with.
1.40 markus 790: */
1.229 djm 791: if (!want_cert && ip_hostkeys != NULL) {
792: ip_status = check_key_in_hostkeys(ip_hostkeys, host_key,
793: &ip_found);
1.38 markus 794: if (host_status == HOST_CHANGED &&
1.229 djm 795: (ip_status != HOST_CHANGED ||
796: (ip_found != NULL &&
1.280 markus 797: !sshkey_equal(ip_found->key, host_found->key))))
1.38 markus 798: host_ip_differ = 1;
799: } else
800: ip_status = host_status;
801:
802: switch (host_status) {
803: case HOST_OK:
804: /* The host is known and the key matches. */
1.219 djm 805: debug("Host '%.200s' is known and matches the %s host %s.",
806: host, type, want_cert ? "certificate" : "key");
1.229 djm 807: debug("Found %s in %s:%lu", want_cert ? "CA key" : "key",
808: host_found->file, host_found->line);
1.281 djm 809: if (want_cert &&
810: !check_host_cert(options.host_key_alias == NULL ?
811: hostname : options.host_key_alias, host_key))
1.219 djm 812: goto fail;
1.88 markus 813: if (options.check_host_ip && ip_status == HOST_NEW) {
1.219 djm 814: if (readonly || want_cert)
1.138 itojun 815: logit("%s host key for IP address "
1.108 markus 816: "'%.128s' not in list of known hosts.",
817: type, ip);
1.234 djm 818: else if (!add_host_to_hostfile(user_hostfiles[0], ip,
1.160 djm 819: host_key, options.hash_known_hosts))
1.138 itojun 820: logit("Failed to add the %s host key for IP "
1.108 markus 821: "address '%.128s' to the list of known "
1.262 dtucker 822: "hosts (%.500s).", type, ip,
1.234 djm 823: user_hostfiles[0]);
1.88 markus 824: else
1.138 itojun 825: logit("Warning: Permanently added the %s host "
1.108 markus 826: "key for IP address '%.128s' to the list "
827: "of known hosts.", type, ip);
1.209 grunk 828: } else if (options.visual_host_key) {
1.259 djm 829: fp = sshkey_fingerprint(host_key,
1.254 djm 830: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 831: ra = sshkey_fingerprint(host_key,
1.254 djm 832: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 833: if (fp == NULL || ra == NULL)
834: fatal("%s: sshkey_fingerprint fail", __func__);
1.264 djm 835: logit("Host key fingerprint is %s\n%s", fp, ra);
1.238 djm 836: free(ra);
837: free(fp);
1.38 markus 838: }
1.257 djm 839: hostkey_trusted = 1;
1.38 markus 840: break;
841: case HOST_NEW:
1.197 dtucker 842: if (options.host_key_alias == NULL && port != 0 &&
843: port != SSH_DEFAULT_PORT) {
844: debug("checking without port identifier");
1.212 stevesk 845: if (check_host_key(hostname, hostaddr, 0, host_key,
1.234 djm 846: ROQUIET, user_hostfiles, num_user_hostfiles,
847: system_hostfiles, num_system_hostfiles) == 0) {
1.197 dtucker 848: debug("found matching key w/out port");
849: break;
850: }
851: }
1.219 djm 852: if (readonly || want_cert)
1.108 markus 853: goto fail;
1.38 markus 854: /* The host is new. */
855: if (options.strict_host_key_checking == 1) {
1.108 markus 856: /*
857: * User has requested strict host key checking. We
858: * will not add the host key automatically. The only
859: * alternative left is to abort.
860: */
861: error("No %s host key is known for %.200s and you "
862: "have requested strict checking.", type, host);
863: goto fail;
1.38 markus 864: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 865: char msg1[1024], msg2[1024];
866:
1.229 djm 867: if (show_other_keys(host_hostkeys, host_key))
1.145 jakob 868: snprintf(msg1, sizeof(msg1),
1.168 djm 869: "\nbut keys of different type are already"
870: " known for this host.");
1.145 jakob 871: else
872: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 873: /* The default */
1.259 djm 874: fp = sshkey_fingerprint(host_key,
1.254 djm 875: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 876: ra = sshkey_fingerprint(host_key,
1.254 djm 877: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 878: if (fp == NULL || ra == NULL)
879: fatal("%s: sshkey_fingerprint fail", __func__);
1.145 jakob 880: msg2[0] = '\0';
881: if (options.verify_host_key_dns) {
1.153 jakob 882: if (matching_host_key_dns)
1.145 jakob 883: snprintf(msg2, sizeof(msg2),
884: "Matching host key fingerprint"
885: " found in DNS.\n");
886: else
887: snprintf(msg2, sizeof(msg2),
888: "No matching host key fingerprint"
889: " found in DNS.\n");
890: }
1.119 markus 891: snprintf(msg, sizeof(msg),
1.108 markus 892: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 893: "established%s\n"
1.209 grunk 894: "%s key fingerprint is %s.%s%s\n%s"
1.108 markus 895: "Are you sure you want to continue connecting "
1.132 markus 896: "(yes/no)? ",
1.209 grunk 897: host, ip, msg1, type, fp,
898: options.visual_host_key ? "\n" : "",
899: options.visual_host_key ? ra : "",
900: msg2);
1.238 djm 901: free(ra);
902: free(fp);
1.119 markus 903: if (!confirm(msg))
1.108 markus 904: goto fail;
1.257 djm 905: hostkey_trusted = 1; /* user explicitly confirmed */
1.38 markus 906: }
1.161 djm 907: /*
908: * If not in strict mode, add the key automatically to the
909: * local known_hosts file.
910: */
1.88 markus 911: if (options.check_host_ip && ip_status == HOST_NEW) {
1.229 djm 912: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
1.38 markus 913: hostp = hostline;
1.161 djm 914: if (options.hash_known_hosts) {
915: /* Add hash of host and IP separately */
1.234 djm 916: r = add_host_to_hostfile(user_hostfiles[0],
917: host, host_key, options.hash_known_hosts) &&
918: add_host_to_hostfile(user_hostfiles[0], ip,
1.161 djm 919: host_key, options.hash_known_hosts);
920: } else {
921: /* Add unhashed "host,ip" */
1.234 djm 922: r = add_host_to_hostfile(user_hostfiles[0],
1.161 djm 923: hostline, host_key,
924: options.hash_known_hosts);
925: }
926: } else {
1.234 djm 927: r = add_host_to_hostfile(user_hostfiles[0], host,
928: host_key, options.hash_known_hosts);
1.38 markus 929: hostp = host;
1.161 djm 930: }
1.38 markus 931:
1.161 djm 932: if (!r)
1.138 itojun 933: logit("Failed to add the host to the list of known "
1.234 djm 934: "hosts (%.500s).", user_hostfiles[0]);
1.38 markus 935: else
1.138 itojun 936: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 937: "list of known hosts.", hostp, type);
1.38 markus 938: break;
1.220 djm 939: case HOST_REVOKED:
940: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
941: error("@ WARNING: REVOKED HOST KEY DETECTED! @");
942: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
943: error("The %s host key for %s is marked as revoked.", type, host);
944: error("This could mean that a stolen key is being used to");
945: error("impersonate this host.");
946:
947: /*
948: * If strict host key checking is in use, the user will have
949: * to edit the key manually and we can only abort.
950: */
951: if (options.strict_host_key_checking) {
952: error("%s host key for %.200s was revoked and you have "
953: "requested strict checking.", type, host);
954: goto fail;
955: }
956: goto continue_unsafe;
957:
1.38 markus 958: case HOST_CHANGED:
1.219 djm 959: if (want_cert) {
960: /*
961: * This is only a debug() since it is valid to have
962: * CAs with wildcard DNS matches that don't match
963: * all hosts that one might visit.
964: */
965: debug("Host certificate authority does not "
1.229 djm 966: "match %s in %s:%lu", CA_MARKER,
967: host_found->file, host_found->line);
1.219 djm 968: goto fail;
969: }
1.197 dtucker 970: if (readonly == ROQUIET)
971: goto fail;
1.38 markus 972: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 973: char *key_msg;
1.38 markus 974: if (ip_status == HOST_NEW)
1.158 avsm 975: key_msg = "is unknown";
1.38 markus 976: else if (ip_status == HOST_OK)
1.158 avsm 977: key_msg = "is unchanged";
1.38 markus 978: else
1.158 avsm 979: key_msg = "has a different value";
1.38 markus 980: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
981: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
982: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 983: error("The %s host key for %s has changed,", type, host);
1.208 ian 984: error("and the key for the corresponding IP address %s", ip);
1.158 avsm 985: error("%s. This could either mean that", key_msg);
1.38 markus 986: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 987: error("and its host key have changed at the same time.");
1.88 markus 988: if (ip_status != HOST_NEW)
1.229 djm 989: error("Offending key for IP in %s:%lu",
990: ip_found->file, ip_found->line);
1.38 markus 991: }
992: /* The host key has changed. */
1.150 jakob 993: warn_changed_key(host_key);
1.38 markus 994: error("Add correct host key in %.100s to get rid of this message.",
1.234 djm 995: user_hostfiles[0]);
1.280 markus 996: error("Offending %s key in %s:%lu",
997: sshkey_type(host_found->key),
1.229 djm 998: host_found->file, host_found->line);
1.38 markus 999:
1.40 markus 1000: /*
1001: * If strict host key checking is in use, the user will have
1002: * to edit the key manually and we can only abort.
1003: */
1.108 markus 1004: if (options.strict_host_key_checking) {
1005: error("%s host key for %.200s has changed and you have "
1006: "requested strict checking.", type, host);
1007: goto fail;
1008: }
1.38 markus 1009:
1.220 djm 1010: continue_unsafe:
1.40 markus 1011: /*
1012: * If strict host key checking has not been requested, allow
1.144 djm 1013: * the connection but without MITM-able authentication or
1.194 stevesk 1014: * forwarding.
1.40 markus 1015: */
1.38 markus 1016: if (options.password_authentication) {
1.108 markus 1017: error("Password authentication is disabled to avoid "
1018: "man-in-the-middle attacks.");
1.38 markus 1019: options.password_authentication = 0;
1.210 dtucker 1020: cancelled_forwarding = 1;
1.144 djm 1021: }
1022: if (options.kbd_interactive_authentication) {
1023: error("Keyboard-interactive authentication is disabled"
1024: " to avoid man-in-the-middle attacks.");
1025: options.kbd_interactive_authentication = 0;
1026: options.challenge_response_authentication = 0;
1.210 dtucker 1027: cancelled_forwarding = 1;
1.144 djm 1028: }
1029: if (options.challenge_response_authentication) {
1030: error("Challenge/response authentication is disabled"
1031: " to avoid man-in-the-middle attacks.");
1032: options.challenge_response_authentication = 0;
1.210 dtucker 1033: cancelled_forwarding = 1;
1.38 markus 1034: }
1035: if (options.forward_agent) {
1.108 markus 1036: error("Agent forwarding is disabled to avoid "
1037: "man-in-the-middle attacks.");
1.38 markus 1038: options.forward_agent = 0;
1.210 dtucker 1039: cancelled_forwarding = 1;
1.83 markus 1040: }
1041: if (options.forward_x11) {
1.108 markus 1042: error("X11 forwarding is disabled to avoid "
1043: "man-in-the-middle attacks.");
1.83 markus 1044: options.forward_x11 = 0;
1.210 dtucker 1045: cancelled_forwarding = 1;
1.83 markus 1046: }
1.108 markus 1047: if (options.num_local_forwards > 0 ||
1048: options.num_remote_forwards > 0) {
1049: error("Port forwarding is disabled to avoid "
1050: "man-in-the-middle attacks.");
1051: options.num_local_forwards =
1.118 deraadt 1052: options.num_remote_forwards = 0;
1.210 dtucker 1053: cancelled_forwarding = 1;
1.194 stevesk 1054: }
1055: if (options.tun_open != SSH_TUNMODE_NO) {
1056: error("Tunnel forwarding is disabled to avoid "
1057: "man-in-the-middle attacks.");
1058: options.tun_open = SSH_TUNMODE_NO;
1.210 dtucker 1059: cancelled_forwarding = 1;
1.38 markus 1060: }
1.210 dtucker 1061: if (options.exit_on_forward_failure && cancelled_forwarding)
1062: fatal("Error: forwarding disabled due to host key "
1063: "check failure");
1064:
1.40 markus 1065: /*
1066: * XXX Should permit the user to change to use the new id.
1067: * This could be done by converting the host key to an
1068: * identifying sentence, tell that the host identifies itself
1.218 dtucker 1069: * by that sentence, and ask the user if he/she wishes to
1.40 markus 1070: * accept the authentication.
1071: */
1.38 markus 1072: break;
1.132 markus 1073: case HOST_FOUND:
1074: fatal("internal error");
1075: break;
1.88 markus 1076: }
1077:
1078: if (options.check_host_ip && host_status != HOST_CHANGED &&
1079: ip_status == HOST_CHANGED) {
1.119 markus 1080: snprintf(msg, sizeof(msg),
1081: "Warning: the %s host key for '%.200s' "
1082: "differs from the key for the IP address '%.128s'"
1.229 djm 1083: "\nOffending key for IP in %s:%lu",
1084: type, host, ip, ip_found->file, ip_found->line);
1.119 markus 1085: if (host_status == HOST_OK) {
1086: len = strlen(msg);
1087: snprintf(msg + len, sizeof(msg) - len,
1.229 djm 1088: "\nMatching host key in %s:%lu",
1089: host_found->file, host_found->line);
1.119 markus 1090: }
1.88 markus 1091: if (options.strict_host_key_checking == 1) {
1.143 djm 1092: logit("%s", msg);
1.108 markus 1093: error("Exiting, you have requested strict checking.");
1094: goto fail;
1.88 markus 1095: } else if (options.strict_host_key_checking == 2) {
1.119 markus 1096: strlcat(msg, "\nAre you sure you want "
1097: "to continue connecting (yes/no)? ", sizeof(msg));
1098: if (!confirm(msg))
1.108 markus 1099: goto fail;
1.119 markus 1100: } else {
1.143 djm 1101: logit("%s", msg);
1.88 markus 1102: }
1.257 djm 1103: }
1104:
1105: if (!hostkey_trusted && options.update_hostkeys) {
1106: debug("%s: hostkey not known or explicitly trusted: "
1107: "disabling UpdateHostkeys", __func__);
1108: options.update_hostkeys = 0;
1.38 markus 1109: }
1.82 provos 1110:
1.238 djm 1111: free(ip);
1112: free(host);
1.229 djm 1113: if (host_hostkeys != NULL)
1114: free_hostkeys(host_hostkeys);
1115: if (ip_hostkeys != NULL)
1116: free_hostkeys(ip_hostkeys);
1.108 markus 1117: return 0;
1118:
1119: fail:
1.220 djm 1120: if (want_cert && host_status != HOST_REVOKED) {
1.219 djm 1121: /*
1122: * No matching certificate. Downgrade cert to raw key and
1123: * search normally.
1124: */
1125: debug("No matching CA found. Retry with plain key");
1.280 markus 1126: if ((r = sshkey_from_private(host_key, &raw_key)) != 0)
1127: fatal("%s: sshkey_from_private: %s",
1128: __func__, ssh_err(r));
1129: if ((r = sshkey_drop_cert(raw_key)) != 0)
1130: fatal("Couldn't drop certificate: %s", ssh_err(r));
1.219 djm 1131: host_key = raw_key;
1132: goto retry;
1133: }
1134: if (raw_key != NULL)
1.280 markus 1135: sshkey_free(raw_key);
1.238 djm 1136: free(ip);
1137: free(host);
1.229 djm 1138: if (host_hostkeys != NULL)
1139: free_hostkeys(host_hostkeys);
1140: if (ip_hostkeys != NULL)
1141: free_hostkeys(ip_hostkeys);
1.108 markus 1142: return -1;
1143: }
1144:
1.140 jakob 1145: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 1146: int
1.279 markus 1147: verify_host_key(char *host, struct sockaddr *hostaddr, struct sshkey *host_key)
1.108 markus 1148: {
1.267 djm 1149: u_int i;
1.250 djm 1150: int r = -1, flags = 0;
1.267 djm 1151: char valid[64], *fp = NULL, *cafp = NULL;
1.252 djm 1152: struct sshkey *plain = NULL;
1.229 djm 1153:
1.252 djm 1154: if ((fp = sshkey_fingerprint(host_key,
1.254 djm 1155: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1.252 djm 1156: error("%s: fingerprint host key: %s", __func__, ssh_err(r));
1157: r = -1;
1158: goto out;
1159: }
1160:
1.267 djm 1161: if (sshkey_is_cert(host_key)) {
1162: if ((cafp = sshkey_fingerprint(host_key->cert->signature_key,
1163: options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL) {
1164: error("%s: fingerprint CA key: %s",
1165: __func__, ssh_err(r));
1166: r = -1;
1167: goto out;
1168: }
1169: sshkey_format_cert_validity(host_key->cert,
1170: valid, sizeof(valid));
1171: debug("Server host certificate: %s %s, serial %llu "
1172: "ID \"%s\" CA %s %s valid %s",
1173: sshkey_ssh_name(host_key), fp,
1.269 djm 1174: (unsigned long long)host_key->cert->serial,
1175: host_key->cert->key_id,
1.267 djm 1176: sshkey_ssh_name(host_key->cert->signature_key), cafp,
1177: valid);
1178: for (i = 0; i < host_key->cert->nprincipals; i++) {
1179: debug2("Server host certificate hostname: %s",
1180: host_key->cert->principals[i]);
1181: }
1182: } else {
1.276 djm 1183: debug("Server host key: %s %s", sshkey_ssh_name(host_key), fp);
1.267 djm 1184: }
1.252 djm 1185:
1186: if (sshkey_equal(previous_host_key, host_key)) {
1187: debug2("%s: server host key %s %s matches cached key",
1188: __func__, sshkey_type(host_key), fp);
1189: r = 0;
1190: goto out;
1191: }
1192:
1193: /* Check in RevokedHostKeys file if specified */
1194: if (options.revoked_host_keys != NULL) {
1195: r = sshkey_check_revoked(host_key, options.revoked_host_keys);
1196: switch (r) {
1197: case 0:
1198: break; /* not revoked */
1199: case SSH_ERR_KEY_REVOKED:
1200: error("Host key %s %s revoked by file %s",
1201: sshkey_type(host_key), fp,
1202: options.revoked_host_keys);
1203: r = -1;
1204: goto out;
1205: default:
1206: error("Error checking host key %s %s in "
1207: "revoked keys file %s: %s", sshkey_type(host_key),
1208: fp, options.revoked_host_keys, ssh_err(r));
1209: r = -1;
1210: goto out;
1211: }
1.250 djm 1212: }
1213:
1.247 djm 1214: if (options.verify_host_key_dns) {
1215: /*
1216: * XXX certs are not yet supported for DNS, so downgrade
1217: * them and try the plain key.
1218: */
1.252 djm 1219: if ((r = sshkey_from_private(host_key, &plain)) != 0)
1220: goto out;
1221: if (sshkey_is_cert(plain))
1222: sshkey_drop_cert(plain);
1.247 djm 1223: if (verify_host_key_dns(host, hostaddr, plain, &flags) == 0) {
1224: if (flags & DNS_VERIFY_FOUND) {
1225: if (options.verify_host_key_dns == 1 &&
1226: flags & DNS_VERIFY_MATCH &&
1227: flags & DNS_VERIFY_SECURE) {
1.250 djm 1228: r = 0;
1.252 djm 1229: goto out;
1.247 djm 1230: }
1231: if (flags & DNS_VERIFY_MATCH) {
1232: matching_host_key_dns = 1;
1233: } else {
1234: warn_changed_key(plain);
1235: error("Update the SSHFP RR in DNS "
1236: "with the new host key to get rid "
1237: "of this message.");
1238: }
1.153 jakob 1239: }
1.140 jakob 1240: }
1241: }
1.250 djm 1242: r = check_host_key(host, hostaddr, options.port, host_key, RDRW,
1.234 djm 1243: options.user_hostfiles, options.num_user_hostfiles,
1244: options.system_hostfiles, options.num_system_hostfiles);
1.250 djm 1245:
1.252 djm 1246: out:
1247: sshkey_free(plain);
1248: free(fp);
1.267 djm 1249: free(cafp);
1.250 djm 1250: if (r == 0 && host_key != NULL) {
1.280 markus 1251: sshkey_free(previous_host_key);
1252: r = sshkey_from_private(host_key, &previous_host_key);
1.250 djm 1253: }
1254:
1255: return r;
1.51 markus 1256: }
1.70 markus 1257:
1.51 markus 1258: /*
1259: * Starts a dialog with the server, and authenticates the current user on the
1260: * server. This does not need any extra privileges. The basic connection
1261: * to the server must already have been established before this is called.
1262: * If login fails, this function prints an error and never returns.
1263: * This function does not require super-user privileges.
1264: */
1265: void
1.120 markus 1266: ssh_login(Sensitive *sensitive, const char *orighost,
1.229 djm 1267: struct sockaddr *hostaddr, u_short port, struct passwd *pw, int timeout_ms)
1.51 markus 1268: {
1.241 djm 1269: char *host;
1.70 markus 1270: char *server_user, *local_user;
1271:
1272: local_user = xstrdup(pw->pw_name);
1273: server_user = options.user ? options.user : local_user;
1.51 markus 1274:
1275: /* Convert the user-supplied hostname into all lowercase. */
1276: host = xstrdup(orighost);
1.241 djm 1277: lowercase(host);
1.51 markus 1278:
1279: /* Exchange protocol version identification strings with the server. */
1.202 djm 1280: ssh_exchange_identification(timeout_ms);
1.51 markus 1281:
1282: /* Put the connection into non-blocking mode. */
1283: packet_set_nonblocking();
1284:
1285: /* key exchange */
1286: /* authenticate user */
1.261 dtucker 1287: debug("Authenticating to %s:%d as '%s'", host, port, server_user);
1.276 djm 1288: ssh_kex2(host, hostaddr, port);
1289: ssh_userauth2(local_user, server_user, host, sensitive);
1.238 djm 1290: free(local_user);
1.97 markus 1291: }
1292:
1293: void
1294: ssh_put_password(char *password)
1295: {
1296: int size;
1297: char *padded;
1298:
1.99 deraadt 1299: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 1300: packet_put_cstring(password);
1.99 deraadt 1301: return;
1302: }
1.272 deraadt 1303: size = ROUNDUP(strlen(password) + 1, 32);
1.179 djm 1304: padded = xcalloc(1, size);
1.97 markus 1305: strlcpy(padded, password, size);
1306: packet_put_string(padded, size);
1.245 djm 1307: explicit_bzero(padded, size);
1.238 djm 1308: free(padded);
1.132 markus 1309: }
1310:
1311: /* print all known host keys for a given host, but skip keys of given type */
1312: static int
1.279 markus 1313: show_other_keys(struct hostkeys *hostkeys, struct sshkey *key)
1.132 markus 1314: {
1.242 djm 1315: int type[] = {
1316: KEY_RSA,
1317: KEY_DSA,
1318: KEY_ECDSA,
1319: KEY_ED25519,
1320: -1
1321: };
1.229 djm 1322: int i, ret = 0;
1323: char *fp, *ra;
1324: const struct hostkey_entry *found;
1.132 markus 1325:
1326: for (i = 0; type[i] != -1; i++) {
1327: if (type[i] == key->type)
1328: continue;
1.229 djm 1329: if (!lookup_key_in_hostkeys_by_type(hostkeys, type[i], &found))
1.132 markus 1330: continue;
1.259 djm 1331: fp = sshkey_fingerprint(found->key,
1.254 djm 1332: options.fingerprint_hash, SSH_FP_DEFAULT);
1.259 djm 1333: ra = sshkey_fingerprint(found->key,
1.254 djm 1334: options.fingerprint_hash, SSH_FP_RANDOMART);
1.259 djm 1335: if (fp == NULL || ra == NULL)
1336: fatal("%s: sshkey_fingerprint fail", __func__);
1.229 djm 1337: logit("WARNING: %s key found for host %s\n"
1338: "in %s:%lu\n"
1339: "%s key fingerprint %s.",
1340: key_type(found->key),
1341: found->host, found->file, found->line,
1342: key_type(found->key), fp);
1343: if (options.visual_host_key)
1344: logit("%s", ra);
1.238 djm 1345: free(ra);
1346: free(fp);
1.229 djm 1347: ret = 1;
1.132 markus 1348: }
1.229 djm 1349: return ret;
1.150 jakob 1350: }
1351:
1352: static void
1.279 markus 1353: warn_changed_key(struct sshkey *host_key)
1.150 jakob 1354: {
1355: char *fp;
1356:
1.259 djm 1357: fp = sshkey_fingerprint(host_key, options.fingerprint_hash,
1.254 djm 1358: SSH_FP_DEFAULT);
1.259 djm 1359: if (fp == NULL)
1360: fatal("%s: sshkey_fingerprint fail", __func__);
1.150 jakob 1361:
1362: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1363: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1364: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1365: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1366: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.230 markus 1367: error("It is also possible that a host key has just been changed.");
1.150 jakob 1368: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.230 markus 1369: key_type(host_key), fp);
1.150 jakob 1370: error("Please contact your system administrator.");
1371:
1.238 djm 1372: free(fp);
1.171 reyk 1373: }
1374:
1375: /*
1376: * Execute a local command
1377: */
1378: int
1379: ssh_local_cmd(const char *args)
1380: {
1381: char *shell;
1382: pid_t pid;
1383: int status;
1.231 djm 1384: void (*osighand)(int);
1.171 reyk 1385:
1386: if (!options.permit_local_command ||
1387: args == NULL || !*args)
1388: return (1);
1389:
1.226 djm 1390: if ((shell = getenv("SHELL")) == NULL || *shell == '\0')
1.171 reyk 1391: shell = _PATH_BSHELL;
1392:
1.231 djm 1393: osighand = signal(SIGCHLD, SIG_DFL);
1.171 reyk 1394: pid = fork();
1395: if (pid == 0) {
1.232 djm 1396: signal(SIGPIPE, SIG_DFL);
1.171 reyk 1397: debug3("Executing %s -c \"%s\"", shell, args);
1398: execl(shell, shell, "-c", args, (char *)NULL);
1399: error("Couldn't execute %s -c \"%s\": %s",
1400: shell, args, strerror(errno));
1401: _exit(1);
1402: } else if (pid == -1)
1403: fatal("fork failed: %.100s", strerror(errno));
1404: while (waitpid(pid, &status, 0) == -1)
1405: if (errno != EINTR)
1406: fatal("Couldn't wait for child: %s", strerror(errno));
1.231 djm 1407: signal(SIGCHLD, osighand);
1.171 reyk 1408:
1409: if (!WIFEXITED(status))
1410: return (1);
1411:
1412: return (WEXITSTATUS(status));
1.266 jcs 1413: }
1414:
1415: void
1.279 markus 1416: maybe_add_key_to_agent(char *authfile, struct sshkey *private, char *comment,
1.266 jcs 1417: char *passphrase)
1418: {
1419: int auth_sock = -1, r;
1420:
1421: if (options.add_keys_to_agent == 0)
1422: return;
1423:
1424: if ((r = ssh_get_authentication_socket(&auth_sock)) != 0) {
1425: debug3("no authentication agent, not adding key");
1426: return;
1427: }
1428:
1429: if (options.add_keys_to_agent == 2 &&
1430: !ask_permission("Add key %s (%s) to agent?", authfile, comment)) {
1431: debug3("user denied adding this key");
1.273 dtucker 1432: close(auth_sock);
1.266 jcs 1433: return;
1434: }
1435:
1436: if ((r = ssh_add_identity_constrained(auth_sock, private, comment, 0,
1437: (options.add_keys_to_agent == 3))) == 0)
1438: debug("identity added to agent: %s", authfile);
1439: else
1440: debug("could not add identity to agent: %s (%d)", authfile, r);
1.273 dtucker 1441: close(auth_sock);
1.1 deraadt 1442: }
![[BACK]](/icons/back.gif){kind=icon}
Return to sshconnect.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh