Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.143
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"
1.143 ! djm 16: RCSID("$OpenBSD: sshconnect.c,v 1.142 2003/05/23 08:29:30 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:
1.124 markus 43: /* import */
1.43 markus 44: extern Options options;
1.50 markus 45: extern char *__progname;
1.124 markus 46: extern uid_t original_real_uid;
47: extern uid_t original_effective_uid;
1.135 djm 48: extern pid_t proxy_command_pid;
1.91 markus 49:
1.132 markus 50: static int show_other_keys(const char *, Key *);
51:
1.39 deraadt 52: /*
53: * Connect to the given ssh server using a proxy command.
54: */
1.109 itojun 55: static int
1.124 markus 56: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 57: {
1.38 markus 58: Buffer command;
59: const char *cp;
60: char *command_string;
61: int pin[2], pout[2];
1.69 deraadt 62: pid_t pid;
1.49 markus 63: char strport[NI_MAXSERV];
1.38 markus 64:
65: /* Convert the port number into a string. */
1.49 markus 66: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 67:
1.135 djm 68: /*
69: * Build the final command string in the buffer by making the
70: * appropriate substitutions to the given proxy command.
71: *
72: * Use "exec" to avoid "sh -c" processes on some platforms
73: * (e.g. Solaris)
74: */
1.38 markus 75: buffer_init(&command);
1.135 djm 76: buffer_append(&command, "exec ", 5);
77:
1.38 markus 78: for (cp = proxy_command; *cp; cp++) {
79: if (cp[0] == '%' && cp[1] == '%') {
80: buffer_append(&command, "%", 1);
81: cp++;
82: continue;
83: }
84: if (cp[0] == '%' && cp[1] == 'h') {
85: buffer_append(&command, host, strlen(host));
86: cp++;
87: continue;
88: }
89: if (cp[0] == '%' && cp[1] == 'p') {
1.49 markus 90: buffer_append(&command, strport, strlen(strport));
1.38 markus 91: cp++;
92: continue;
93: }
94: buffer_append(&command, cp, 1);
95: }
96: buffer_append(&command, "\0", 1);
97:
98: /* Get the final command string. */
99: command_string = buffer_ptr(&command);
100:
101: /* Create pipes for communicating with the proxy. */
102: if (pipe(pin) < 0 || pipe(pout) < 0)
103: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 104: strerror(errno));
1.38 markus 105:
106: debug("Executing proxy command: %.500s", command_string);
107:
108: /* Fork and execute the proxy command. */
109: if ((pid = fork()) == 0) {
110: char *argv[10];
111:
112: /* Child. Permanently give up superuser privileges. */
1.124 markus 113: seteuid(original_real_uid);
114: setuid(original_real_uid);
1.38 markus 115:
116: /* Redirect stdin and stdout. */
117: close(pin[1]);
118: if (pin[0] != 0) {
119: if (dup2(pin[0], 0) < 0)
120: perror("dup2 stdin");
121: close(pin[0]);
122: }
123: close(pout[0]);
124: if (dup2(pout[1], 1) < 0)
125: perror("dup2 stdout");
126: /* Cannot be 1 because pin allocated two descriptors. */
127: close(pout[1]);
128:
129: /* Stderr is left as it is so that error messages get
130: printed on the user's terminal. */
1.89 markus 131: argv[0] = _PATH_BSHELL;
1.38 markus 132: argv[1] = "-c";
133: argv[2] = command_string;
134: argv[3] = NULL;
135:
136: /* Execute the proxy command. Note that we gave up any
137: extra privileges above. */
1.89 markus 138: execv(argv[0], argv);
139: perror(argv[0]);
1.38 markus 140: exit(1);
141: }
142: /* Parent. */
143: if (pid < 0)
144: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 145: else
146: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 147:
148: /* Close child side of the descriptors. */
149: close(pin[0]);
150: close(pout[1]);
151:
152: /* Free the command name. */
153: buffer_free(&command);
154:
155: /* Set the connection file descriptors. */
156: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 157:
1.110 markus 158: /* Indicate OK return */
159: return 0;
1.1 deraadt 160: }
161:
1.39 deraadt 162: /*
163: * Creates a (possibly privileged) socket for use as the ssh connection.
164: */
1.109 itojun 165: static int
1.139 markus 166: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 167: {
1.105 markus 168: int sock, gaierr;
169: struct addrinfo hints, *res;
1.1 deraadt 170:
1.40 markus 171: /*
172: * If we are running as root and want to connect to a privileged
173: * port, bind our own socket to a privileged port.
174: */
1.38 markus 175: if (privileged) {
176: int p = IPPORT_RESERVED - 1;
1.124 markus 177: PRIV_START;
1.139 markus 178: sock = rresvport_af(&p, ai->ai_family);
1.124 markus 179: PRIV_END;
1.38 markus 180: if (sock < 0)
1.139 markus 181: error("rresvport: af=%d %.100s", ai->ai_family,
182: strerror(errno));
1.55 markus 183: else
184: debug("Allocated local port %d.", p);
1.105 markus 185: return sock;
186: }
1.139 markus 187: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.105 markus 188: if (sock < 0)
189: error("socket: %.100s", strerror(errno));
190:
191: /* Bind the socket to an alternative local IP address */
192: if (options.bind_address == NULL)
193: return sock;
194:
195: memset(&hints, 0, sizeof(hints));
1.139 markus 196: hints.ai_family = ai->ai_family;
197: hints.ai_socktype = ai->ai_socktype;
198: hints.ai_protocol = ai->ai_protocol;
1.105 markus 199: hints.ai_flags = AI_PASSIVE;
200: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
201: if (gaierr) {
202: error("getaddrinfo: %s: %s", options.bind_address,
203: gai_strerror(gaierr));
204: close(sock);
205: return -1;
206: }
207: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
208: error("bind: %s: %s", options.bind_address, strerror(errno));
209: close(sock);
210: freeaddrinfo(res);
211: return -1;
1.38 markus 212: }
1.105 markus 213: freeaddrinfo(res);
1.38 markus 214: return sock;
1.1 deraadt 215: }
216:
1.141 djm 217: static int
218: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
219: socklen_t addrlen, int timeout)
220: {
221: fd_set *fdset;
222: struct timeval tv;
223: socklen_t optlen;
1.142 djm 224: int fdsetsz, optval, rc, result = -1;
1.141 djm 225:
226: if (timeout <= 0)
227: return (connect(sockfd, serv_addr, addrlen));
228:
229: if (fcntl(sockfd, F_SETFL, O_NONBLOCK) < 0)
230: return (-1);
231:
232: rc = connect(sockfd, serv_addr, addrlen);
233: if (rc == 0)
234: return (0);
235: if (errno != EINPROGRESS)
236: return (-1);
237:
238: fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask);
239: fdset = (fd_set *)xmalloc(fdsetsz);
240:
241: memset(fdset, '\0', fdsetsz);
242: FD_SET(sockfd, fdset);
243: tv.tv_sec = timeout;
244: tv.tv_usec = 0;
245:
246: for(;;) {
247: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
248: if (rc != -1 || errno != EINTR)
249: break;
250: }
251:
252: switch(rc) {
253: case 0:
254: /* Timed out */
255: errno = ETIMEDOUT;
1.142 djm 256: break;
1.141 djm 257: case -1:
258: /* Select error */
259: debug("select: %s", strerror(errno));
1.142 djm 260: break;
1.141 djm 261: case 1:
262: /* Completed or failed */
263: optval = 0;
264: optlen = sizeof(optval);
265: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
266: &optlen) == -1)
267: debug("getsockopt: %s", strerror(errno));
1.142 djm 268: break;
1.141 djm 269: if (optval != 0) {
270: errno = optval;
1.142 djm 271: break;
1.141 djm 272: }
1.142 djm 273: result = 0;
1.141 djm 274: break;
275: default:
276: /* Should not occur */
277: fatal("Bogus return (%d) from select()", rc);
278: }
279:
1.142 djm 280: xfree(fdset);
281: return (result);
1.141 djm 282: }
283:
1.39 deraadt 284: /*
1.49 markus 285: * Opens a TCP/IP connection to the remote server on the given host.
286: * The address of the remote host will be returned in hostaddr.
1.124 markus 287: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 288: * a privileged port will be allocated to make the connection.
1.124 markus 289: * This requires super-user privileges if needpriv is true.
1.39 deraadt 290: * Connection_attempts specifies the maximum number of tries (one per
291: * second). If proxy_command is non-NULL, it specifies the command (with %h
292: * and %p substituted for host and port, respectively) to use to contact
293: * the daemon.
1.110 markus 294: * Return values:
295: * 0 for OK
296: * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
297: * ECONNABORTED if we failed without a "Connection refused"
298: * Suitable error messages for the connection failure will already have been
299: * printed.
1.39 deraadt 300: */
1.38 markus 301: int
1.49 markus 302: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 303: u_short port, int family, int connection_attempts,
1.124 markus 304: int needpriv, const char *proxy_command)
1.1 deraadt 305: {
1.90 markus 306: int gaierr;
307: int on = 1;
1.49 markus 308: int sock = -1, attempt;
1.90 markus 309: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 310: struct addrinfo hints, *ai, *aitop;
1.90 markus 311: struct servent *sp;
1.110 markus 312: /*
313: * Did we get only other errors than "Connection refused" (which
314: * should block fallback to rsh and similar), or did we get at least
315: * one "Connection refused"?
316: */
317: int full_failure = 1;
1.38 markus 318:
1.136 markus 319: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 320:
321: /* Get default port if port has not been set. */
322: if (port == 0) {
323: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
324: if (sp)
325: port = ntohs(sp->s_port);
326: else
327: port = SSH_DEFAULT_PORT;
328: }
329: /* If a proxy command is given, connect using it. */
330: if (proxy_command != NULL)
1.124 markus 331: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 332:
333: /* No proxy command. */
334:
1.49 markus 335: memset(&hints, 0, sizeof(hints));
1.115 markus 336: hints.ai_family = family;
1.49 markus 337: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 338: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 339: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 340: fatal("%s: %.100s: %s", __progname, host,
341: gai_strerror(gaierr));
1.38 markus 342:
1.46 markus 343: /*
344: * Try to connect several times. On some machines, the first time
345: * will sometimes fail. In general socket code appears to behave
346: * quite magically on many machines.
1.110 markus 347: */
348: for (attempt = 0; ;) {
1.38 markus 349: if (attempt > 0)
350: debug("Trying again...");
351:
1.49 markus 352: /* Loop through addresses for this host, and try each one in
1.68 markus 353: sequence until the connection succeeds. */
1.49 markus 354: for (ai = aitop; ai; ai = ai->ai_next) {
355: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
356: continue;
357: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
358: ntop, sizeof(ntop), strport, sizeof(strport),
359: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
360: error("ssh_connect: getnameinfo failed");
361: continue;
362: }
363: debug("Connecting to %.200s [%.100s] port %s.",
364: host, ntop, strport);
365:
366: /* Create a socket for connecting. */
1.139 markus 367: sock = ssh_create_socket(needpriv, ai);
1.49 markus 368: if (sock < 0)
1.110 markus 369: /* Any error is already output */
1.49 markus 370: continue;
371:
1.141 djm 372: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
373: options.connection_timeout) >= 0) {
1.49 markus 374: /* Successful connection. */
1.102 markus 375: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 376: break;
1.49 markus 377: } else {
1.110 markus 378: if (errno == ECONNREFUSED)
379: full_failure = 0;
1.131 itojun 380: debug("connect to address %s port %s: %s",
381: ntop, strport, strerror(errno));
1.40 markus 382: /*
383: * Close the failed socket; there appear to
384: * be some problems when reusing a socket for
385: * which connect() has already returned an
386: * error.
387: */
1.38 markus 388: close(sock);
389: }
390: }
1.49 markus 391: if (ai)
392: break; /* Successful connection. */
1.1 deraadt 393:
1.110 markus 394: attempt++;
395: if (attempt >= connection_attempts)
396: break;
1.38 markus 397: /* Sleep a moment before retrying. */
398: sleep(1);
399: }
1.49 markus 400:
401: freeaddrinfo(aitop);
402:
1.38 markus 403: /* Return failure if we didn't get a successful connection. */
1.130 itojun 404: if (attempt >= connection_attempts) {
1.138 itojun 405: logit("ssh: connect to host %s port %s: %s",
1.130 itojun 406: host, strport, strerror(errno));
1.110 markus 407: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.130 itojun 408: }
1.38 markus 409:
410: debug("Connection established.");
1.90 markus 411:
412: /* Set keepalives if requested. */
413: if (options.keepalives &&
414: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
415: sizeof(on)) < 0)
416: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 417:
418: /* Set the connection. */
419: packet_set_connection(sock, sock);
1.1 deraadt 420:
1.110 markus 421: return 0;
1.59 markus 422: }
423:
1.43 markus 424: /*
1.39 deraadt 425: * Waits for the server identification string, and sends our own
426: * identification string.
427: */
1.109 itojun 428: static void
1.95 itojun 429: ssh_exchange_identification(void)
1.1 deraadt 430: {
1.38 markus 431: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 432: int remote_major, remote_minor, i, mismatch;
1.38 markus 433: int connection_in = packet_get_connection_in();
434: int connection_out = packet_get_connection_out();
1.93 stevesk 435: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 436:
437: /* Read other side\'s version identification. */
1.75 markus 438: for (;;) {
439: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 440: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 441: if (len < 0)
442: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
443: if (len != 1)
444: fatal("ssh_exchange_identification: Connection closed by remote host");
445: if (buf[i] == '\r') {
446: buf[i] = '\n';
447: buf[i + 1] = 0;
448: continue; /**XXX wait for \n */
449: }
450: if (buf[i] == '\n') {
451: buf[i + 1] = 0;
452: break;
453: }
1.38 markus 454: }
1.75 markus 455: buf[sizeof(buf) - 1] = 0;
1.76 markus 456: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 457: break;
1.75 markus 458: debug("ssh_exchange_identification: %s", buf);
1.38 markus 459: }
1.59 markus 460: server_version_string = xstrdup(buf);
1.38 markus 461:
1.40 markus 462: /*
463: * Check that the versions match. In future this might accept
464: * several versions and set appropriate flags to handle them.
465: */
1.59 markus 466: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
467: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 468: fatal("Bad remote protocol version identification: '%.100s'", buf);
469: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 470: remote_major, remote_minor, remote_version);
1.38 markus 471:
1.59 markus 472: compat_datafellows(remote_version);
1.64 markus 473: mismatch = 0;
1.59 markus 474:
1.116 deraadt 475: switch (remote_major) {
1.64 markus 476: case 1:
477: if (remote_minor == 99 &&
478: (options.protocol & SSH_PROTO_2) &&
479: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
480: enable_compat20();
481: break;
482: }
483: if (!(options.protocol & SSH_PROTO_1)) {
484: mismatch = 1;
485: break;
486: }
487: if (remote_minor < 3) {
488: fatal("Remote machine has too old SSH software version.");
1.81 markus 489: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 490: /* We speak 1.3, too. */
491: enable_compat13();
1.81 markus 492: minor1 = 3;
1.64 markus 493: if (options.forward_agent) {
1.138 itojun 494: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 495: options.forward_agent = 0;
496: }
497: }
498: break;
499: case 2:
500: if (options.protocol & SSH_PROTO_2) {
501: enable_compat20();
502: break;
1.38 markus 503: }
1.64 markus 504: /* FALLTHROUGH */
1.68 markus 505: default:
1.64 markus 506: mismatch = 1;
507: break;
1.38 markus 508: }
1.64 markus 509: if (mismatch)
1.38 markus 510: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 511: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
512: remote_major);
1.38 markus 513: /* Send our own protocol version identification. */
514: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 515: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 516: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 517: SSH_VERSION);
1.45 deraadt 518: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 519: fatal("write: %.100s", strerror(errno));
1.59 markus 520: client_version_string = xstrdup(buf);
521: chop(client_version_string);
522: chop(server_version_string);
523: debug("Local version string %.100s", client_version_string);
1.1 deraadt 524: }
525:
1.96 markus 526: /* defaults to 'no' */
1.109 itojun 527: static int
1.112 markus 528: confirm(const char *prompt)
1.1 deraadt 529: {
1.119 markus 530: const char *msg, *again = "Please type 'yes' or 'no': ";
531: char *p;
532: int ret = -1;
1.96 markus 533:
534: if (options.batch_mode)
535: return 0;
1.119 markus 536: for (msg = prompt;;msg = again) {
537: p = read_passphrase(msg, RP_ECHO);
538: if (p == NULL ||
539: (p[0] == '\0') || (p[0] == '\n') ||
540: strncasecmp(p, "no", 2) == 0)
541: ret = 0;
1.127 markus 542: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 543: ret = 1;
544: if (p)
545: xfree(p);
546: if (ret != -1)
547: return ret;
1.1 deraadt 548: }
549: }
550:
1.39 deraadt 551: /*
1.108 markus 552: * check whether the supplied host key is valid, return -1 if the key
553: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 554: */
1.109 itojun 555: static int
1.70 markus 556: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 557: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 558: {
1.58 markus 559: Key *file_key;
1.72 markus 560: char *type = key_type(host_key);
1.46 markus 561: char *ip = NULL;
1.100 markus 562: char hostline[1000], *hostp, *fp;
1.38 markus 563: HostStatus host_status;
564: HostStatus ip_status;
1.49 markus 565: int local = 0, host_ip_differ = 0;
566: char ntop[NI_MAXHOST];
1.119 markus 567: char msg[1024];
1.132 markus 568: int len, host_line, ip_line, has_keys;
1.85 markus 569: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 570:
571: /*
572: * Force accepting of the host key for loopback/localhost. The
573: * problem is that if the home directory is NFS-mounted to multiple
574: * machines, localhost will refer to a different machine in each of
575: * them, and the user will get bogus HOST_CHANGED warnings. This
576: * essentially disables host authentication for localhost; however,
577: * this is probably not a real problem.
578: */
1.70 markus 579: /** hostaddr == 0! */
1.49 markus 580: switch (hostaddr->sa_family) {
581: case AF_INET:
1.108 markus 582: local = (ntohl(((struct sockaddr_in *)hostaddr)->
583: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 584: break;
585: case AF_INET6:
1.108 markus 586: local = IN6_IS_ADDR_LOOPBACK(
587: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 588: break;
589: default:
590: local = 0;
591: break;
592: }
1.111 markus 593: if (options.no_host_authentication_for_localhost == 1 && local &&
594: options.host_key_alias == NULL) {
1.88 markus 595: debug("Forcing accepting of host key for "
596: "loopback/localhost.");
1.108 markus 597: return 0;
1.49 markus 598: }
1.42 markus 599:
600: /*
1.88 markus 601: * We don't have the remote ip-address for connections
602: * using a proxy command
1.42 markus 603: */
1.84 markus 604: if (options.proxy_command == NULL) {
605: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 606: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 607: fatal("check_host_key: getnameinfo failed");
608: ip = xstrdup(ntop);
609: } else {
610: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 611: }
1.88 markus 612: /*
613: * Turn off check_host_ip if the connection is to localhost, via proxy
614: * command or if we don't have a hostname to compare with
615: */
616: if (options.check_host_ip &&
617: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
618: options.check_host_ip = 0;
1.86 markus 619:
620: /*
621: * Allow the user to record the key under a different name. This is
622: * useful for ssh tunneling over forwarded connections or if you run
623: * multiple sshd's on different ports on the same machine.
624: */
625: if (options.host_key_alias != NULL) {
626: host = options.host_key_alias;
627: debug("using hostkeyalias: %s", host);
1.84 markus 628: }
1.38 markus 629:
1.46 markus 630: /*
631: * Store the host key from the known host file in here so that we can
632: * compare it with the key for the IP address.
633: */
1.58 markus 634: file_key = key_new(host_key->type);
1.38 markus 635:
1.40 markus 636: /*
637: * Check if the host key is present in the user\'s list of known
638: * hosts or in the systemwide list.
639: */
1.85 markus 640: host_file = user_hostfile;
1.108 markus 641: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 642: file_key, &host_line);
1.85 markus 643: if (host_status == HOST_NEW) {
644: host_file = system_hostfile;
1.108 markus 645: host_status = check_host_in_hostfile(host_file, host, host_key,
646: file_key, &host_line);
1.85 markus 647: }
1.40 markus 648: /*
649: * Also perform check for the ip address, skip the check if we are
650: * localhost or the hostname was an ip address to begin with
651: */
1.88 markus 652: if (options.check_host_ip) {
1.58 markus 653: Key *ip_key = key_new(host_key->type);
1.38 markus 654:
1.85 markus 655: ip_file = user_hostfile;
1.108 markus 656: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
657: ip_key, &ip_line);
1.85 markus 658: if (ip_status == HOST_NEW) {
659: ip_file = system_hostfile;
1.108 markus 660: ip_status = check_host_in_hostfile(ip_file, ip,
661: host_key, ip_key, &ip_line);
1.85 markus 662: }
1.38 markus 663: if (host_status == HOST_CHANGED &&
1.58 markus 664: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 665: host_ip_differ = 1;
666:
1.58 markus 667: key_free(ip_key);
1.38 markus 668: } else
669: ip_status = host_status;
670:
1.58 markus 671: key_free(file_key);
1.38 markus 672:
673: switch (host_status) {
674: case HOST_OK:
675: /* The host is known and the key matches. */
1.72 markus 676: debug("Host '%.200s' is known and matches the %s host key.",
677: host, type);
1.85 markus 678: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 679: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 680: if (readonly)
1.138 itojun 681: logit("%s host key for IP address "
1.108 markus 682: "'%.128s' not in list of known hosts.",
683: type, ip);
684: else if (!add_host_to_hostfile(user_hostfile, ip,
1.118 deraadt 685: host_key))
1.138 itojun 686: logit("Failed to add the %s host key for IP "
1.108 markus 687: "address '%.128s' to the list of known "
688: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 689: else
1.138 itojun 690: logit("Warning: Permanently added the %s host "
1.108 markus 691: "key for IP address '%.128s' to the list "
692: "of known hosts.", type, ip);
1.38 markus 693: }
694: break;
695: case HOST_NEW:
1.108 markus 696: if (readonly)
697: goto fail;
1.38 markus 698: /* The host is new. */
699: if (options.strict_host_key_checking == 1) {
1.108 markus 700: /*
701: * User has requested strict host key checking. We
702: * will not add the host key automatically. The only
703: * alternative left is to abort.
704: */
705: error("No %s host key is known for %.200s and you "
706: "have requested strict checking.", type, host);
707: goto fail;
1.38 markus 708: } else if (options.strict_host_key_checking == 2) {
1.132 markus 709: has_keys = show_other_keys(host, host_key);
1.38 markus 710: /* The default */
1.100 markus 711: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.119 markus 712: snprintf(msg, sizeof(msg),
1.108 markus 713: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 714: "established%s\n"
1.72 markus 715: "%s key fingerprint is %s.\n"
1.108 markus 716: "Are you sure you want to continue connecting "
1.132 markus 717: "(yes/no)? ",
1.137 deraadt 718: host, ip,
719: has_keys ? ",\nbut keys of different type are already "
720: "known for this host." : ".",
721: type, fp);
1.100 markus 722: xfree(fp);
1.119 markus 723: if (!confirm(msg))
1.108 markus 724: goto fail;
1.38 markus 725: }
1.88 markus 726: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 727: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
728: hostp = hostline;
729: } else
730: hostp = host;
731:
1.108 markus 732: /*
733: * If not in strict mode, add the key automatically to the
734: * local known_hosts file.
735: */
1.70 markus 736: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.138 itojun 737: logit("Failed to add the host to the list of known "
1.108 markus 738: "hosts (%.500s).", user_hostfile);
1.38 markus 739: else
1.138 itojun 740: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 741: "list of known hosts.", hostp, type);
1.38 markus 742: break;
743: case HOST_CHANGED:
744: if (options.check_host_ip && host_ip_differ) {
745: char *msg;
746: if (ip_status == HOST_NEW)
747: msg = "is unknown";
748: else if (ip_status == HOST_OK)
749: msg = "is unchanged";
750: else
751: msg = "has a different value";
752: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
753: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
754: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 755: error("The %s host key for %s has changed,", type, host);
1.38 markus 756: error("and the key for the according IP address %s", ip);
757: error("%s. This could either mean that", msg);
758: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 759: error("and its host key have changed at the same time.");
1.88 markus 760: if (ip_status != HOST_NEW)
1.85 markus 761: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 762: }
763: /* The host key has changed. */
1.100 markus 764: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 765: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 766: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 767: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
768: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
769: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 770: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 771: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.100 markus 772: type, fp);
1.38 markus 773: error("Please contact your system administrator.");
774: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 775: user_hostfile);
1.85 markus 776: error("Offending key in %s:%d", host_file, host_line);
1.100 markus 777: xfree(fp);
1.38 markus 778:
1.40 markus 779: /*
780: * If strict host key checking is in use, the user will have
781: * to edit the key manually and we can only abort.
782: */
1.108 markus 783: if (options.strict_host_key_checking) {
784: error("%s host key for %.200s has changed and you have "
785: "requested strict checking.", type, host);
786: goto fail;
787: }
1.38 markus 788:
1.40 markus 789: /*
790: * If strict host key checking has not been requested, allow
791: * the connection but without password authentication or
792: * agent forwarding.
793: */
1.38 markus 794: if (options.password_authentication) {
1.108 markus 795: error("Password authentication is disabled to avoid "
796: "man-in-the-middle attacks.");
1.38 markus 797: options.password_authentication = 0;
798: }
799: if (options.forward_agent) {
1.108 markus 800: error("Agent forwarding is disabled to avoid "
801: "man-in-the-middle attacks.");
1.38 markus 802: options.forward_agent = 0;
1.83 markus 803: }
804: if (options.forward_x11) {
1.108 markus 805: error("X11 forwarding is disabled to avoid "
806: "man-in-the-middle attacks.");
1.83 markus 807: options.forward_x11 = 0;
808: }
1.108 markus 809: if (options.num_local_forwards > 0 ||
810: options.num_remote_forwards > 0) {
811: error("Port forwarding is disabled to avoid "
812: "man-in-the-middle attacks.");
813: options.num_local_forwards =
1.118 deraadt 814: options.num_remote_forwards = 0;
1.38 markus 815: }
1.40 markus 816: /*
817: * XXX Should permit the user to change to use the new id.
818: * This could be done by converting the host key to an
819: * identifying sentence, tell that the host identifies itself
820: * by that sentence, and ask the user if he/she whishes to
821: * accept the authentication.
822: */
1.38 markus 823: break;
1.132 markus 824: case HOST_FOUND:
825: fatal("internal error");
826: break;
1.88 markus 827: }
828:
829: if (options.check_host_ip && host_status != HOST_CHANGED &&
830: ip_status == HOST_CHANGED) {
1.119 markus 831: snprintf(msg, sizeof(msg),
832: "Warning: the %s host key for '%.200s' "
833: "differs from the key for the IP address '%.128s'"
834: "\nOffending key for IP in %s:%d",
835: type, host, ip, ip_file, ip_line);
836: if (host_status == HOST_OK) {
837: len = strlen(msg);
838: snprintf(msg + len, sizeof(msg) - len,
839: "\nMatching host key in %s:%d",
1.125 deraadt 840: host_file, host_line);
1.119 markus 841: }
1.88 markus 842: if (options.strict_host_key_checking == 1) {
1.143 ! djm 843: logit("%s", msg);
1.108 markus 844: error("Exiting, you have requested strict checking.");
845: goto fail;
1.88 markus 846: } else if (options.strict_host_key_checking == 2) {
1.119 markus 847: strlcat(msg, "\nAre you sure you want "
848: "to continue connecting (yes/no)? ", sizeof(msg));
849: if (!confirm(msg))
1.108 markus 850: goto fail;
1.119 markus 851: } else {
1.143 ! djm 852: logit("%s", msg);
1.88 markus 853: }
1.38 markus 854: }
1.82 provos 855:
856: xfree(ip);
1.108 markus 857: return 0;
858:
859: fail:
860: xfree(ip);
861: return -1;
862: }
863:
1.140 jakob 864: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 865: int
866: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
867: {
868: struct stat st;
1.140 jakob 869:
870: #ifdef DNS
871: if (options.verify_host_key_dns) {
872: switch(verify_host_key_dns(host, hostaddr, host_key)) {
873: case DNS_VERIFY_OK:
874: return 0;
875: case DNS_VERIFY_FAILED:
876: return -1;
877: case DNS_VERIFY_ERROR:
878: break;
879: default:
880: debug3("bad return value from verify_host_key_dns");
881: break;
882: }
883: }
884: #endif /* DNS */
1.108 markus 885:
886: /* return ok if the key can be found in an old keyfile */
887: if (stat(options.system_hostfile2, &st) == 0 ||
888: stat(options.user_hostfile2, &st) == 0) {
889: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
890: options.user_hostfile2, options.system_hostfile2) == 0)
891: return 0;
892: }
893: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
894: options.user_hostfile, options.system_hostfile);
1.51 markus 895: }
1.70 markus 896:
1.51 markus 897: /*
898: * Starts a dialog with the server, and authenticates the current user on the
899: * server. This does not need any extra privileges. The basic connection
900: * to the server must already have been established before this is called.
901: * If login fails, this function prints an error and never returns.
902: * This function does not require super-user privileges.
903: */
904: void
1.120 markus 905: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 906: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 907: {
908: char *host, *cp;
1.70 markus 909: char *server_user, *local_user;
910:
911: local_user = xstrdup(pw->pw_name);
912: server_user = options.user ? options.user : local_user;
1.51 markus 913:
914: /* Convert the user-supplied hostname into all lowercase. */
915: host = xstrdup(orighost);
916: for (cp = host; *cp; cp++)
917: if (isupper(*cp))
918: *cp = tolower(*cp);
919:
920: /* Exchange protocol version identification strings with the server. */
921: ssh_exchange_identification();
922:
923: /* Put the connection into non-blocking mode. */
924: packet_set_nonblocking();
925:
926: /* key exchange */
927: /* authenticate user */
1.59 markus 928: if (compat20) {
929: ssh_kex2(host, hostaddr);
1.120 markus 930: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 931: } else {
932: ssh_kex(host, hostaddr);
1.120 markus 933: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 934: }
1.97 markus 935: }
936:
937: void
938: ssh_put_password(char *password)
939: {
940: int size;
941: char *padded;
942:
1.99 deraadt 943: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 944: packet_put_cstring(password);
1.99 deraadt 945: return;
946: }
1.97 markus 947: size = roundup(strlen(password) + 1, 32);
948: padded = xmalloc(size);
949: memset(padded, 0, size);
950: strlcpy(padded, password, size);
951: packet_put_string(padded, size);
952: memset(padded, 0, size);
953: xfree(padded);
1.132 markus 954: }
955:
956: static int
957: show_key_from_file(const char *file, const char *host, int keytype)
958: {
959: Key *found;
960: char *fp;
961: int line, ret;
962:
963: found = key_new(keytype);
964: if ((ret = lookup_key_in_hostfile_by_type(file, host,
965: keytype, found, &line))) {
966: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 967: logit("WARNING: %s key found for host %s\n"
1.133 markus 968: "in %s:%d\n"
1.132 markus 969: "%s key fingerprint %s.",
970: key_type(found), host, file, line,
971: key_type(found), fp);
972: xfree(fp);
973: }
974: key_free(found);
975: return (ret);
976: }
977:
978: /* print all known host keys for a given host, but skip keys of given type */
979: static int
980: show_other_keys(const char *host, Key *key)
981: {
982: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
983: int i, found = 0;
984:
985: for (i = 0; type[i] != -1; i++) {
986: if (type[i] == key->type)
987: continue;
988: if (type[i] != KEY_RSA1 &&
989: show_key_from_file(options.user_hostfile2, host, type[i])) {
990: found = 1;
991: continue;
992: }
993: if (type[i] != KEY_RSA1 &&
994: show_key_from_file(options.system_hostfile2, host, type[i])) {
995: found = 1;
996: continue;
997: }
998: if (show_key_from_file(options.user_hostfile, host, type[i])) {
999: found = 1;
1000: continue;
1001: }
1002: if (show_key_from_file(options.system_hostfile, host, type[i])) {
1003: found = 1;
1004: continue;
1005: }
1006: debug2("no key of type %d for host %s", type[i], host);
1007: }
1008: return (found);
1.1 deraadt 1009: }
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