Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.145
1.1 deraadt 1: /*
1.39 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
5: * Code to connect to a remote host, and to perform the client side of the
6: * login (authentication) dialog.
1.78 deraadt 7: *
8: * As far as I am concerned, the code I have written for this software
9: * can be used freely for any purpose. Any derived versions of this
10: * software must be clearly marked as such, and if the derived work is
11: * incompatible with the protocol description in the RFC file, it must be
12: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 13: */
1.1 deraadt 14:
15: #include "includes.h"
1.145 ! jakob 16: RCSID("$OpenBSD: sshconnect.c,v 1.144 2003/06/04 08:25:18 djm Exp $");
1.1 deraadt 17:
1.66 markus 18: #include <openssl/bn.h>
1.71 markus 19:
1.91 markus 20: #include "ssh.h"
1.1 deraadt 21: #include "xmalloc.h"
22: #include "rsa.h"
1.59 markus 23: #include "buffer.h"
1.1 deraadt 24: #include "packet.h"
25: #include "uidswap.h"
1.21 markus 26: #include "compat.h"
1.58 markus 27: #include "key.h"
1.71 markus 28: #include "sshconnect.h"
1.58 markus 29: #include "hostfile.h"
1.91 markus 30: #include "log.h"
31: #include "readconf.h"
32: #include "atomicio.h"
33: #include "misc.h"
1.119 markus 34: #include "readpass.h"
1.51 markus 35:
1.140 jakob 36: #ifdef DNS
37: #include "dns.h"
38: #endif
39:
1.70 markus 40: char *client_version_string = NULL;
41: char *server_version_string = NULL;
1.59 markus 42:
1.145 ! jakob 43: #ifdef DNS
! 44: int verified_host_key_dns = 0;
! 45: #endif
! 46:
1.124 markus 47: /* import */
1.43 markus 48: extern Options options;
1.50 markus 49: extern char *__progname;
1.124 markus 50: extern uid_t original_real_uid;
51: extern uid_t original_effective_uid;
1.135 djm 52: extern pid_t proxy_command_pid;
1.91 markus 53:
1.132 markus 54: static int show_other_keys(const char *, Key *);
55:
1.39 deraadt 56: /*
57: * Connect to the given ssh server using a proxy command.
58: */
1.109 itojun 59: static int
1.124 markus 60: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 61: {
1.38 markus 62: Buffer command;
63: const char *cp;
64: char *command_string;
65: int pin[2], pout[2];
1.69 deraadt 66: pid_t pid;
1.49 markus 67: char strport[NI_MAXSERV];
1.38 markus 68:
69: /* Convert the port number into a string. */
1.49 markus 70: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 71:
1.135 djm 72: /*
73: * Build the final command string in the buffer by making the
74: * appropriate substitutions to the given proxy command.
75: *
76: * Use "exec" to avoid "sh -c" processes on some platforms
77: * (e.g. Solaris)
78: */
1.38 markus 79: buffer_init(&command);
1.135 djm 80: buffer_append(&command, "exec ", 5);
81:
1.38 markus 82: for (cp = proxy_command; *cp; cp++) {
83: if (cp[0] == '%' && cp[1] == '%') {
84: buffer_append(&command, "%", 1);
85: cp++;
86: continue;
87: }
88: if (cp[0] == '%' && cp[1] == 'h') {
89: buffer_append(&command, host, strlen(host));
90: cp++;
91: continue;
92: }
93: if (cp[0] == '%' && cp[1] == 'p') {
1.49 markus 94: buffer_append(&command, strport, strlen(strport));
1.38 markus 95: cp++;
96: continue;
97: }
98: buffer_append(&command, cp, 1);
99: }
100: buffer_append(&command, "\0", 1);
101:
102: /* Get the final command string. */
103: command_string = buffer_ptr(&command);
104:
105: /* Create pipes for communicating with the proxy. */
106: if (pipe(pin) < 0 || pipe(pout) < 0)
107: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 108: strerror(errno));
1.38 markus 109:
110: debug("Executing proxy command: %.500s", command_string);
111:
112: /* Fork and execute the proxy command. */
113: if ((pid = fork()) == 0) {
114: char *argv[10];
115:
116: /* Child. Permanently give up superuser privileges. */
1.124 markus 117: seteuid(original_real_uid);
118: setuid(original_real_uid);
1.38 markus 119:
120: /* Redirect stdin and stdout. */
121: close(pin[1]);
122: if (pin[0] != 0) {
123: if (dup2(pin[0], 0) < 0)
124: perror("dup2 stdin");
125: close(pin[0]);
126: }
127: close(pout[0]);
128: if (dup2(pout[1], 1) < 0)
129: perror("dup2 stdout");
130: /* Cannot be 1 because pin allocated two descriptors. */
131: close(pout[1]);
132:
133: /* Stderr is left as it is so that error messages get
134: printed on the user's terminal. */
1.89 markus 135: argv[0] = _PATH_BSHELL;
1.38 markus 136: argv[1] = "-c";
137: argv[2] = command_string;
138: argv[3] = NULL;
139:
140: /* Execute the proxy command. Note that we gave up any
141: extra privileges above. */
1.89 markus 142: execv(argv[0], argv);
143: perror(argv[0]);
1.38 markus 144: exit(1);
145: }
146: /* Parent. */
147: if (pid < 0)
148: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 149: else
150: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 151:
152: /* Close child side of the descriptors. */
153: close(pin[0]);
154: close(pout[1]);
155:
156: /* Free the command name. */
157: buffer_free(&command);
158:
159: /* Set the connection file descriptors. */
160: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 161:
1.110 markus 162: /* Indicate OK return */
163: return 0;
1.1 deraadt 164: }
165:
1.39 deraadt 166: /*
167: * Creates a (possibly privileged) socket for use as the ssh connection.
168: */
1.109 itojun 169: static int
1.139 markus 170: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 171: {
1.105 markus 172: int sock, gaierr;
173: struct addrinfo hints, *res;
1.1 deraadt 174:
1.40 markus 175: /*
176: * If we are running as root and want to connect to a privileged
177: * port, bind our own socket to a privileged port.
178: */
1.38 markus 179: if (privileged) {
180: int p = IPPORT_RESERVED - 1;
1.124 markus 181: PRIV_START;
1.139 markus 182: sock = rresvport_af(&p, ai->ai_family);
1.124 markus 183: PRIV_END;
1.38 markus 184: if (sock < 0)
1.139 markus 185: error("rresvport: af=%d %.100s", ai->ai_family,
186: strerror(errno));
1.55 markus 187: else
188: debug("Allocated local port %d.", p);
1.105 markus 189: return sock;
190: }
1.139 markus 191: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.105 markus 192: if (sock < 0)
193: error("socket: %.100s", strerror(errno));
194:
195: /* Bind the socket to an alternative local IP address */
196: if (options.bind_address == NULL)
197: return sock;
198:
199: memset(&hints, 0, sizeof(hints));
1.139 markus 200: hints.ai_family = ai->ai_family;
201: hints.ai_socktype = ai->ai_socktype;
202: hints.ai_protocol = ai->ai_protocol;
1.105 markus 203: hints.ai_flags = AI_PASSIVE;
204: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
205: if (gaierr) {
206: error("getaddrinfo: %s: %s", options.bind_address,
207: gai_strerror(gaierr));
208: close(sock);
209: return -1;
210: }
211: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
212: error("bind: %s: %s", options.bind_address, strerror(errno));
213: close(sock);
214: freeaddrinfo(res);
215: return -1;
1.38 markus 216: }
1.105 markus 217: freeaddrinfo(res);
1.38 markus 218: return sock;
1.1 deraadt 219: }
220:
1.141 djm 221: static int
222: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
223: socklen_t addrlen, int timeout)
224: {
225: fd_set *fdset;
226: struct timeval tv;
227: socklen_t optlen;
1.142 djm 228: int fdsetsz, optval, rc, result = -1;
1.141 djm 229:
230: if (timeout <= 0)
231: return (connect(sockfd, serv_addr, addrlen));
232:
233: if (fcntl(sockfd, F_SETFL, O_NONBLOCK) < 0)
234: return (-1);
235:
236: rc = connect(sockfd, serv_addr, addrlen);
237: if (rc == 0)
238: return (0);
239: if (errno != EINPROGRESS)
240: return (-1);
241:
242: fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask);
243: fdset = (fd_set *)xmalloc(fdsetsz);
244:
245: memset(fdset, '\0', fdsetsz);
246: FD_SET(sockfd, fdset);
247: tv.tv_sec = timeout;
248: tv.tv_usec = 0;
249:
250: for(;;) {
251: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
252: if (rc != -1 || errno != EINTR)
253: break;
254: }
255:
256: switch(rc) {
257: case 0:
258: /* Timed out */
259: errno = ETIMEDOUT;
1.142 djm 260: break;
1.141 djm 261: case -1:
262: /* Select error */
263: debug("select: %s", strerror(errno));
1.142 djm 264: break;
1.141 djm 265: case 1:
266: /* Completed or failed */
267: optval = 0;
268: optlen = sizeof(optval);
269: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
270: &optlen) == -1)
271: debug("getsockopt: %s", strerror(errno));
1.142 djm 272: break;
1.141 djm 273: if (optval != 0) {
274: errno = optval;
1.142 djm 275: break;
1.141 djm 276: }
1.142 djm 277: result = 0;
1.141 djm 278: break;
279: default:
280: /* Should not occur */
281: fatal("Bogus return (%d) from select()", rc);
282: }
283:
1.142 djm 284: xfree(fdset);
285: return (result);
1.141 djm 286: }
287:
1.39 deraadt 288: /*
1.49 markus 289: * Opens a TCP/IP connection to the remote server on the given host.
290: * The address of the remote host will be returned in hostaddr.
1.124 markus 291: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 292: * a privileged port will be allocated to make the connection.
1.124 markus 293: * This requires super-user privileges if needpriv is true.
1.39 deraadt 294: * Connection_attempts specifies the maximum number of tries (one per
295: * second). If proxy_command is non-NULL, it specifies the command (with %h
296: * and %p substituted for host and port, respectively) to use to contact
297: * the daemon.
1.110 markus 298: * Return values:
299: * 0 for OK
300: * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
301: * ECONNABORTED if we failed without a "Connection refused"
302: * Suitable error messages for the connection failure will already have been
303: * printed.
1.39 deraadt 304: */
1.38 markus 305: int
1.49 markus 306: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 307: u_short port, int family, int connection_attempts,
1.124 markus 308: int needpriv, const char *proxy_command)
1.1 deraadt 309: {
1.90 markus 310: int gaierr;
311: int on = 1;
1.49 markus 312: int sock = -1, attempt;
1.90 markus 313: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 314: struct addrinfo hints, *ai, *aitop;
1.90 markus 315: struct servent *sp;
1.110 markus 316: /*
317: * Did we get only other errors than "Connection refused" (which
318: * should block fallback to rsh and similar), or did we get at least
319: * one "Connection refused"?
320: */
321: int full_failure = 1;
1.38 markus 322:
1.136 markus 323: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 324:
325: /* Get default port if port has not been set. */
326: if (port == 0) {
327: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
328: if (sp)
329: port = ntohs(sp->s_port);
330: else
331: port = SSH_DEFAULT_PORT;
332: }
333: /* If a proxy command is given, connect using it. */
334: if (proxy_command != NULL)
1.124 markus 335: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 336:
337: /* No proxy command. */
338:
1.49 markus 339: memset(&hints, 0, sizeof(hints));
1.115 markus 340: hints.ai_family = family;
1.49 markus 341: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 342: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 343: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 344: fatal("%s: %.100s: %s", __progname, host,
345: gai_strerror(gaierr));
1.38 markus 346:
1.46 markus 347: /*
348: * Try to connect several times. On some machines, the first time
349: * will sometimes fail. In general socket code appears to behave
350: * quite magically on many machines.
1.110 markus 351: */
352: for (attempt = 0; ;) {
1.38 markus 353: if (attempt > 0)
354: debug("Trying again...");
355:
1.49 markus 356: /* Loop through addresses for this host, and try each one in
1.68 markus 357: sequence until the connection succeeds. */
1.49 markus 358: for (ai = aitop; ai; ai = ai->ai_next) {
359: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
360: continue;
361: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
362: ntop, sizeof(ntop), strport, sizeof(strport),
363: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
364: error("ssh_connect: getnameinfo failed");
365: continue;
366: }
367: debug("Connecting to %.200s [%.100s] port %s.",
368: host, ntop, strport);
369:
370: /* Create a socket for connecting. */
1.139 markus 371: sock = ssh_create_socket(needpriv, ai);
1.49 markus 372: if (sock < 0)
1.110 markus 373: /* Any error is already output */
1.49 markus 374: continue;
375:
1.141 djm 376: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
377: options.connection_timeout) >= 0) {
1.49 markus 378: /* Successful connection. */
1.102 markus 379: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 380: break;
1.49 markus 381: } else {
1.110 markus 382: if (errno == ECONNREFUSED)
383: full_failure = 0;
1.131 itojun 384: debug("connect to address %s port %s: %s",
385: ntop, strport, strerror(errno));
1.40 markus 386: /*
387: * Close the failed socket; there appear to
388: * be some problems when reusing a socket for
389: * which connect() has already returned an
390: * error.
391: */
1.38 markus 392: close(sock);
393: }
394: }
1.49 markus 395: if (ai)
396: break; /* Successful connection. */
1.1 deraadt 397:
1.110 markus 398: attempt++;
399: if (attempt >= connection_attempts)
400: break;
1.38 markus 401: /* Sleep a moment before retrying. */
402: sleep(1);
403: }
1.49 markus 404:
405: freeaddrinfo(aitop);
406:
1.38 markus 407: /* Return failure if we didn't get a successful connection. */
1.130 itojun 408: if (attempt >= connection_attempts) {
1.138 itojun 409: logit("ssh: connect to host %s port %s: %s",
1.130 itojun 410: host, strport, strerror(errno));
1.110 markus 411: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.130 itojun 412: }
1.38 markus 413:
414: debug("Connection established.");
1.90 markus 415:
416: /* Set keepalives if requested. */
417: if (options.keepalives &&
418: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
419: sizeof(on)) < 0)
420: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 421:
422: /* Set the connection. */
423: packet_set_connection(sock, sock);
1.1 deraadt 424:
1.110 markus 425: return 0;
1.59 markus 426: }
427:
1.43 markus 428: /*
1.39 deraadt 429: * Waits for the server identification string, and sends our own
430: * identification string.
431: */
1.109 itojun 432: static void
1.95 itojun 433: ssh_exchange_identification(void)
1.1 deraadt 434: {
1.38 markus 435: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 436: int remote_major, remote_minor, i, mismatch;
1.38 markus 437: int connection_in = packet_get_connection_in();
438: int connection_out = packet_get_connection_out();
1.93 stevesk 439: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 440:
441: /* Read other side\'s version identification. */
1.75 markus 442: for (;;) {
443: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 444: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 445: if (len < 0)
446: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
447: if (len != 1)
448: fatal("ssh_exchange_identification: Connection closed by remote host");
449: if (buf[i] == '\r') {
450: buf[i] = '\n';
451: buf[i + 1] = 0;
452: continue; /**XXX wait for \n */
453: }
454: if (buf[i] == '\n') {
455: buf[i + 1] = 0;
456: break;
457: }
1.38 markus 458: }
1.75 markus 459: buf[sizeof(buf) - 1] = 0;
1.76 markus 460: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 461: break;
1.75 markus 462: debug("ssh_exchange_identification: %s", buf);
1.38 markus 463: }
1.59 markus 464: server_version_string = xstrdup(buf);
1.38 markus 465:
1.40 markus 466: /*
467: * Check that the versions match. In future this might accept
468: * several versions and set appropriate flags to handle them.
469: */
1.59 markus 470: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
471: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 472: fatal("Bad remote protocol version identification: '%.100s'", buf);
473: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 474: remote_major, remote_minor, remote_version);
1.38 markus 475:
1.59 markus 476: compat_datafellows(remote_version);
1.64 markus 477: mismatch = 0;
1.59 markus 478:
1.116 deraadt 479: switch (remote_major) {
1.64 markus 480: case 1:
481: if (remote_minor == 99 &&
482: (options.protocol & SSH_PROTO_2) &&
483: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
484: enable_compat20();
485: break;
486: }
487: if (!(options.protocol & SSH_PROTO_1)) {
488: mismatch = 1;
489: break;
490: }
491: if (remote_minor < 3) {
492: fatal("Remote machine has too old SSH software version.");
1.81 markus 493: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 494: /* We speak 1.3, too. */
495: enable_compat13();
1.81 markus 496: minor1 = 3;
1.64 markus 497: if (options.forward_agent) {
1.138 itojun 498: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 499: options.forward_agent = 0;
500: }
501: }
502: break;
503: case 2:
504: if (options.protocol & SSH_PROTO_2) {
505: enable_compat20();
506: break;
1.38 markus 507: }
1.64 markus 508: /* FALLTHROUGH */
1.68 markus 509: default:
1.64 markus 510: mismatch = 1;
511: break;
1.38 markus 512: }
1.64 markus 513: if (mismatch)
1.38 markus 514: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 515: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
516: remote_major);
1.38 markus 517: /* Send our own protocol version identification. */
518: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 519: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 520: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 521: SSH_VERSION);
1.45 deraadt 522: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 523: fatal("write: %.100s", strerror(errno));
1.59 markus 524: client_version_string = xstrdup(buf);
525: chop(client_version_string);
526: chop(server_version_string);
527: debug("Local version string %.100s", client_version_string);
1.1 deraadt 528: }
529:
1.96 markus 530: /* defaults to 'no' */
1.109 itojun 531: static int
1.112 markus 532: confirm(const char *prompt)
1.1 deraadt 533: {
1.119 markus 534: const char *msg, *again = "Please type 'yes' or 'no': ";
535: char *p;
536: int ret = -1;
1.96 markus 537:
538: if (options.batch_mode)
539: return 0;
1.119 markus 540: for (msg = prompt;;msg = again) {
541: p = read_passphrase(msg, RP_ECHO);
542: if (p == NULL ||
543: (p[0] == '\0') || (p[0] == '\n') ||
544: strncasecmp(p, "no", 2) == 0)
545: ret = 0;
1.127 markus 546: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 547: ret = 1;
548: if (p)
549: xfree(p);
550: if (ret != -1)
551: return ret;
1.1 deraadt 552: }
553: }
554:
1.39 deraadt 555: /*
1.108 markus 556: * check whether the supplied host key is valid, return -1 if the key
557: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 558: */
1.109 itojun 559: static int
1.70 markus 560: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 561: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 562: {
1.58 markus 563: Key *file_key;
1.72 markus 564: char *type = key_type(host_key);
1.46 markus 565: char *ip = NULL;
1.100 markus 566: char hostline[1000], *hostp, *fp;
1.38 markus 567: HostStatus host_status;
568: HostStatus ip_status;
1.49 markus 569: int local = 0, host_ip_differ = 0;
570: char ntop[NI_MAXHOST];
1.119 markus 571: char msg[1024];
1.145 ! jakob 572: int len, host_line, ip_line;
1.85 markus 573: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 574:
575: /*
576: * Force accepting of the host key for loopback/localhost. The
577: * problem is that if the home directory is NFS-mounted to multiple
578: * machines, localhost will refer to a different machine in each of
579: * them, and the user will get bogus HOST_CHANGED warnings. This
580: * essentially disables host authentication for localhost; however,
581: * this is probably not a real problem.
582: */
1.70 markus 583: /** hostaddr == 0! */
1.49 markus 584: switch (hostaddr->sa_family) {
585: case AF_INET:
1.108 markus 586: local = (ntohl(((struct sockaddr_in *)hostaddr)->
587: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 588: break;
589: case AF_INET6:
1.108 markus 590: local = IN6_IS_ADDR_LOOPBACK(
591: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 592: break;
593: default:
594: local = 0;
595: break;
596: }
1.111 markus 597: if (options.no_host_authentication_for_localhost == 1 && local &&
598: options.host_key_alias == NULL) {
1.88 markus 599: debug("Forcing accepting of host key for "
600: "loopback/localhost.");
1.108 markus 601: return 0;
1.49 markus 602: }
1.42 markus 603:
604: /*
1.88 markus 605: * We don't have the remote ip-address for connections
606: * using a proxy command
1.42 markus 607: */
1.84 markus 608: if (options.proxy_command == NULL) {
609: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 610: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 611: fatal("check_host_key: getnameinfo failed");
612: ip = xstrdup(ntop);
613: } else {
614: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 615: }
1.88 markus 616: /*
617: * Turn off check_host_ip if the connection is to localhost, via proxy
618: * command or if we don't have a hostname to compare with
619: */
620: if (options.check_host_ip &&
621: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
622: options.check_host_ip = 0;
1.86 markus 623:
624: /*
625: * Allow the user to record the key under a different name. This is
626: * useful for ssh tunneling over forwarded connections or if you run
627: * multiple sshd's on different ports on the same machine.
628: */
629: if (options.host_key_alias != NULL) {
630: host = options.host_key_alias;
631: debug("using hostkeyalias: %s", host);
1.84 markus 632: }
1.38 markus 633:
1.46 markus 634: /*
635: * Store the host key from the known host file in here so that we can
636: * compare it with the key for the IP address.
637: */
1.58 markus 638: file_key = key_new(host_key->type);
1.38 markus 639:
1.40 markus 640: /*
641: * Check if the host key is present in the user\'s list of known
642: * hosts or in the systemwide list.
643: */
1.85 markus 644: host_file = user_hostfile;
1.108 markus 645: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 646: file_key, &host_line);
1.85 markus 647: if (host_status == HOST_NEW) {
648: host_file = system_hostfile;
1.108 markus 649: host_status = check_host_in_hostfile(host_file, host, host_key,
650: file_key, &host_line);
1.85 markus 651: }
1.40 markus 652: /*
653: * Also perform check for the ip address, skip the check if we are
654: * localhost or the hostname was an ip address to begin with
655: */
1.88 markus 656: if (options.check_host_ip) {
1.58 markus 657: Key *ip_key = key_new(host_key->type);
1.38 markus 658:
1.85 markus 659: ip_file = user_hostfile;
1.108 markus 660: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
661: ip_key, &ip_line);
1.85 markus 662: if (ip_status == HOST_NEW) {
663: ip_file = system_hostfile;
1.108 markus 664: ip_status = check_host_in_hostfile(ip_file, ip,
665: host_key, ip_key, &ip_line);
1.85 markus 666: }
1.38 markus 667: if (host_status == HOST_CHANGED &&
1.58 markus 668: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 669: host_ip_differ = 1;
670:
1.58 markus 671: key_free(ip_key);
1.38 markus 672: } else
673: ip_status = host_status;
674:
1.58 markus 675: key_free(file_key);
1.38 markus 676:
677: switch (host_status) {
678: case HOST_OK:
679: /* The host is known and the key matches. */
1.72 markus 680: debug("Host '%.200s' is known and matches the %s host key.",
681: host, type);
1.85 markus 682: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 683: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 684: if (readonly)
1.138 itojun 685: logit("%s host key for IP address "
1.108 markus 686: "'%.128s' not in list of known hosts.",
687: type, ip);
688: else if (!add_host_to_hostfile(user_hostfile, ip,
1.118 deraadt 689: host_key))
1.138 itojun 690: logit("Failed to add the %s host key for IP "
1.108 markus 691: "address '%.128s' to the list of known "
692: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 693: else
1.138 itojun 694: logit("Warning: Permanently added the %s host "
1.108 markus 695: "key for IP address '%.128s' to the list "
696: "of known hosts.", type, ip);
1.38 markus 697: }
698: break;
699: case HOST_NEW:
1.108 markus 700: if (readonly)
701: goto fail;
1.38 markus 702: /* The host is new. */
703: if (options.strict_host_key_checking == 1) {
1.108 markus 704: /*
705: * User has requested strict host key checking. We
706: * will not add the host key automatically. The only
707: * alternative left is to abort.
708: */
709: error("No %s host key is known for %.200s and you "
710: "have requested strict checking.", type, host);
711: goto fail;
1.38 markus 712: } else if (options.strict_host_key_checking == 2) {
1.145 ! jakob 713: char msg1[1024], msg2[1024];
! 714:
! 715: if (show_other_keys(host, host_key))
! 716: snprintf(msg1, sizeof(msg1),
! 717: "\nbut keys of different type are already"
! 718: " known for this host.");
! 719: else
! 720: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 721: /* The default */
1.100 markus 722: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.145 ! jakob 723: msg2[0] = '\0';
! 724: #ifdef DNS
! 725: if (options.verify_host_key_dns) {
! 726: if (verified_host_key_dns)
! 727: snprintf(msg2, sizeof(msg2),
! 728: "Matching host key fingerprint"
! 729: " found in DNS.\n");
! 730: else
! 731: snprintf(msg2, sizeof(msg2),
! 732: "No matching host key fingerprint"
! 733: " found in DNS.\n");
! 734: }
! 735: #endif
1.119 markus 736: snprintf(msg, sizeof(msg),
1.108 markus 737: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 738: "established%s\n"
1.145 ! jakob 739: "%s key fingerprint is %s.\n%s"
1.108 markus 740: "Are you sure you want to continue connecting "
1.132 markus 741: "(yes/no)? ",
1.145 ! jakob 742: host, ip, msg1, type, fp, msg2);
1.100 markus 743: xfree(fp);
1.119 markus 744: if (!confirm(msg))
1.108 markus 745: goto fail;
1.38 markus 746: }
1.88 markus 747: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 748: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
749: hostp = hostline;
750: } else
751: hostp = host;
752:
1.108 markus 753: /*
754: * If not in strict mode, add the key automatically to the
755: * local known_hosts file.
756: */
1.70 markus 757: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.138 itojun 758: logit("Failed to add the host to the list of known "
1.108 markus 759: "hosts (%.500s).", user_hostfile);
1.38 markus 760: else
1.138 itojun 761: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 762: "list of known hosts.", hostp, type);
1.38 markus 763: break;
764: case HOST_CHANGED:
765: if (options.check_host_ip && host_ip_differ) {
766: char *msg;
767: if (ip_status == HOST_NEW)
768: msg = "is unknown";
769: else if (ip_status == HOST_OK)
770: msg = "is unchanged";
771: else
772: msg = "has a different value";
773: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
774: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
775: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 776: error("The %s host key for %s has changed,", type, host);
1.38 markus 777: error("and the key for the according IP address %s", ip);
778: error("%s. This could either mean that", msg);
779: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 780: error("and its host key have changed at the same time.");
1.88 markus 781: if (ip_status != HOST_NEW)
1.85 markus 782: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 783: }
784: /* The host key has changed. */
1.100 markus 785: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 786: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 787: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 788: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
789: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
790: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 791: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 792: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.100 markus 793: type, fp);
1.38 markus 794: error("Please contact your system administrator.");
795: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 796: user_hostfile);
1.85 markus 797: error("Offending key in %s:%d", host_file, host_line);
1.100 markus 798: xfree(fp);
1.38 markus 799:
1.40 markus 800: /*
801: * If strict host key checking is in use, the user will have
802: * to edit the key manually and we can only abort.
803: */
1.108 markus 804: if (options.strict_host_key_checking) {
805: error("%s host key for %.200s has changed and you have "
806: "requested strict checking.", type, host);
807: goto fail;
808: }
1.38 markus 809:
1.40 markus 810: /*
811: * If strict host key checking has not been requested, allow
1.144 djm 812: * the connection but without MITM-able authentication or
1.40 markus 813: * agent forwarding.
814: */
1.38 markus 815: if (options.password_authentication) {
1.108 markus 816: error("Password authentication is disabled to avoid "
817: "man-in-the-middle attacks.");
1.38 markus 818: options.password_authentication = 0;
1.144 djm 819: }
820: if (options.kbd_interactive_authentication) {
821: error("Keyboard-interactive authentication is disabled"
822: " to avoid man-in-the-middle attacks.");
823: options.kbd_interactive_authentication = 0;
824: options.challenge_response_authentication = 0;
825: }
826: if (options.challenge_response_authentication) {
827: error("Challenge/response authentication is disabled"
828: " to avoid man-in-the-middle attacks.");
829: options.challenge_response_authentication = 0;
1.38 markus 830: }
831: if (options.forward_agent) {
1.108 markus 832: error("Agent forwarding is disabled to avoid "
833: "man-in-the-middle attacks.");
1.38 markus 834: options.forward_agent = 0;
1.83 markus 835: }
836: if (options.forward_x11) {
1.108 markus 837: error("X11 forwarding is disabled to avoid "
838: "man-in-the-middle attacks.");
1.83 markus 839: options.forward_x11 = 0;
840: }
1.108 markus 841: if (options.num_local_forwards > 0 ||
842: options.num_remote_forwards > 0) {
843: error("Port forwarding is disabled to avoid "
844: "man-in-the-middle attacks.");
845: options.num_local_forwards =
1.118 deraadt 846: options.num_remote_forwards = 0;
1.38 markus 847: }
1.40 markus 848: /*
849: * XXX Should permit the user to change to use the new id.
850: * This could be done by converting the host key to an
851: * identifying sentence, tell that the host identifies itself
852: * by that sentence, and ask the user if he/she whishes to
853: * accept the authentication.
854: */
1.38 markus 855: break;
1.132 markus 856: case HOST_FOUND:
857: fatal("internal error");
858: break;
1.88 markus 859: }
860:
861: if (options.check_host_ip && host_status != HOST_CHANGED &&
862: ip_status == HOST_CHANGED) {
1.119 markus 863: snprintf(msg, sizeof(msg),
864: "Warning: the %s host key for '%.200s' "
865: "differs from the key for the IP address '%.128s'"
866: "\nOffending key for IP in %s:%d",
867: type, host, ip, ip_file, ip_line);
868: if (host_status == HOST_OK) {
869: len = strlen(msg);
870: snprintf(msg + len, sizeof(msg) - len,
871: "\nMatching host key in %s:%d",
1.125 deraadt 872: host_file, host_line);
1.119 markus 873: }
1.88 markus 874: if (options.strict_host_key_checking == 1) {
1.143 djm 875: logit("%s", msg);
1.108 markus 876: error("Exiting, you have requested strict checking.");
877: goto fail;
1.88 markus 878: } else if (options.strict_host_key_checking == 2) {
1.119 markus 879: strlcat(msg, "\nAre you sure you want "
880: "to continue connecting (yes/no)? ", sizeof(msg));
881: if (!confirm(msg))
1.108 markus 882: goto fail;
1.119 markus 883: } else {
1.143 djm 884: logit("%s", msg);
1.88 markus 885: }
1.38 markus 886: }
1.82 provos 887:
888: xfree(ip);
1.108 markus 889: return 0;
890:
891: fail:
892: xfree(ip);
893: return -1;
894: }
895:
1.140 jakob 896: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 897: int
898: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
899: {
900: struct stat st;
1.140 jakob 901:
902: #ifdef DNS
903: if (options.verify_host_key_dns) {
904: switch(verify_host_key_dns(host, hostaddr, host_key)) {
905: case DNS_VERIFY_OK:
1.145 ! jakob 906: #ifdef DNSSEC
1.140 jakob 907: return 0;
1.145 ! jakob 908: #else
! 909: verified_host_key_dns = 1;
! 910: break;
! 911: #endif
1.140 jakob 912: case DNS_VERIFY_FAILED:
913: return -1;
914: case DNS_VERIFY_ERROR:
915: break;
916: default:
917: debug3("bad return value from verify_host_key_dns");
918: break;
919: }
920: }
921: #endif /* DNS */
1.108 markus 922:
923: /* return ok if the key can be found in an old keyfile */
924: if (stat(options.system_hostfile2, &st) == 0 ||
925: stat(options.user_hostfile2, &st) == 0) {
926: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
927: options.user_hostfile2, options.system_hostfile2) == 0)
928: return 0;
929: }
930: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
931: options.user_hostfile, options.system_hostfile);
1.51 markus 932: }
1.70 markus 933:
1.51 markus 934: /*
935: * Starts a dialog with the server, and authenticates the current user on the
936: * server. This does not need any extra privileges. The basic connection
937: * to the server must already have been established before this is called.
938: * If login fails, this function prints an error and never returns.
939: * This function does not require super-user privileges.
940: */
941: void
1.120 markus 942: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 943: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 944: {
945: char *host, *cp;
1.70 markus 946: char *server_user, *local_user;
947:
948: local_user = xstrdup(pw->pw_name);
949: server_user = options.user ? options.user : local_user;
1.51 markus 950:
951: /* Convert the user-supplied hostname into all lowercase. */
952: host = xstrdup(orighost);
953: for (cp = host; *cp; cp++)
954: if (isupper(*cp))
955: *cp = tolower(*cp);
956:
957: /* Exchange protocol version identification strings with the server. */
958: ssh_exchange_identification();
959:
960: /* Put the connection into non-blocking mode. */
961: packet_set_nonblocking();
962:
963: /* key exchange */
964: /* authenticate user */
1.59 markus 965: if (compat20) {
966: ssh_kex2(host, hostaddr);
1.120 markus 967: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 968: } else {
969: ssh_kex(host, hostaddr);
1.120 markus 970: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 971: }
1.97 markus 972: }
973:
974: void
975: ssh_put_password(char *password)
976: {
977: int size;
978: char *padded;
979:
1.99 deraadt 980: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 981: packet_put_cstring(password);
1.99 deraadt 982: return;
983: }
1.97 markus 984: size = roundup(strlen(password) + 1, 32);
985: padded = xmalloc(size);
986: memset(padded, 0, size);
987: strlcpy(padded, password, size);
988: packet_put_string(padded, size);
989: memset(padded, 0, size);
990: xfree(padded);
1.132 markus 991: }
992:
993: static int
994: show_key_from_file(const char *file, const char *host, int keytype)
995: {
996: Key *found;
997: char *fp;
998: int line, ret;
999:
1000: found = key_new(keytype);
1001: if ((ret = lookup_key_in_hostfile_by_type(file, host,
1002: keytype, found, &line))) {
1003: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 1004: logit("WARNING: %s key found for host %s\n"
1.133 markus 1005: "in %s:%d\n"
1.132 markus 1006: "%s key fingerprint %s.",
1007: key_type(found), host, file, line,
1008: key_type(found), fp);
1009: xfree(fp);
1010: }
1011: key_free(found);
1012: return (ret);
1013: }
1014:
1015: /* print all known host keys for a given host, but skip keys of given type */
1016: static int
1017: show_other_keys(const char *host, Key *key)
1018: {
1019: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
1020: int i, found = 0;
1021:
1022: for (i = 0; type[i] != -1; i++) {
1023: if (type[i] == key->type)
1024: continue;
1025: if (type[i] != KEY_RSA1 &&
1026: show_key_from_file(options.user_hostfile2, host, type[i])) {
1027: found = 1;
1028: continue;
1029: }
1030: if (type[i] != KEY_RSA1 &&
1031: show_key_from_file(options.system_hostfile2, host, type[i])) {
1032: found = 1;
1033: continue;
1034: }
1035: if (show_key_from_file(options.user_hostfile, host, type[i])) {
1036: found = 1;
1037: continue;
1038: }
1039: if (show_key_from_file(options.system_hostfile, host, type[i])) {
1040: found = 1;
1041: continue;
1042: }
1043: debug2("no key of type %d for host %s", type[i], host);
1044: }
1045: return (found);
1.1 deraadt 1046: }
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