Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.149
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"
1.149 ! jakob 16: RCSID("$OpenBSD: sshconnect.c,v 1.148 2003/09/18 07:52:54 markus 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: #include "dns.h"
37:
1.70 markus 38: char *client_version_string = NULL;
39: char *server_version_string = NULL;
1.59 markus 40:
1.145 jakob 41: int verified_host_key_dns = 0;
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:
1.147 markus 241: memset(fdset, 0, fdsetsz);
1.141 djm 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,
1.148 markus 266: &optlen) == -1) {
1.141 djm 267: debug("getsockopt: %s", strerror(errno));
1.142 djm 268: break;
1.148 markus 269: }
1.141 djm 270: if (optval != 0) {
271: errno = optval;
1.142 djm 272: break;
1.141 djm 273: }
1.142 djm 274: result = 0;
1.141 djm 275: break;
276: default:
277: /* Should not occur */
278: fatal("Bogus return (%d) from select()", rc);
279: }
280:
1.142 djm 281: xfree(fdset);
282: return (result);
1.141 djm 283: }
284:
1.39 deraadt 285: /*
1.49 markus 286: * Opens a TCP/IP connection to the remote server on the given host.
287: * The address of the remote host will be returned in hostaddr.
1.124 markus 288: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 289: * a privileged port will be allocated to make the connection.
1.124 markus 290: * This requires super-user privileges if needpriv is true.
1.39 deraadt 291: * Connection_attempts specifies the maximum number of tries (one per
292: * second). If proxy_command is non-NULL, it specifies the command (with %h
293: * and %p substituted for host and port, respectively) to use to contact
294: * the daemon.
1.110 markus 295: * Return values:
296: * 0 for OK
297: * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
298: * ECONNABORTED if we failed without a "Connection refused"
299: * Suitable error messages for the connection failure will already have been
300: * printed.
1.39 deraadt 301: */
1.38 markus 302: int
1.49 markus 303: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 304: u_short port, int family, int connection_attempts,
1.124 markus 305: int needpriv, const char *proxy_command)
1.1 deraadt 306: {
1.90 markus 307: int gaierr;
308: int on = 1;
1.49 markus 309: int sock = -1, attempt;
1.90 markus 310: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 311: struct addrinfo hints, *ai, *aitop;
1.90 markus 312: struct servent *sp;
1.110 markus 313: /*
314: * Did we get only other errors than "Connection refused" (which
315: * should block fallback to rsh and similar), or did we get at least
316: * one "Connection refused"?
317: */
318: int full_failure = 1;
1.38 markus 319:
1.136 markus 320: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 321:
322: /* Get default port if port has not been set. */
323: if (port == 0) {
324: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
325: if (sp)
326: port = ntohs(sp->s_port);
327: else
328: port = SSH_DEFAULT_PORT;
329: }
330: /* If a proxy command is given, connect using it. */
331: if (proxy_command != NULL)
1.124 markus 332: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 333:
334: /* No proxy command. */
335:
1.49 markus 336: memset(&hints, 0, sizeof(hints));
1.115 markus 337: hints.ai_family = family;
1.49 markus 338: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 339: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 340: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 341: fatal("%s: %.100s: %s", __progname, host,
342: gai_strerror(gaierr));
1.38 markus 343:
1.46 markus 344: /*
345: * Try to connect several times. On some machines, the first time
346: * will sometimes fail. In general socket code appears to behave
347: * quite magically on many machines.
1.110 markus 348: */
349: for (attempt = 0; ;) {
1.38 markus 350: if (attempt > 0)
351: debug("Trying again...");
352:
1.49 markus 353: /* Loop through addresses for this host, and try each one in
1.68 markus 354: sequence until the connection succeeds. */
1.49 markus 355: for (ai = aitop; ai; ai = ai->ai_next) {
356: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
357: continue;
358: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
359: ntop, sizeof(ntop), strport, sizeof(strport),
360: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
361: error("ssh_connect: getnameinfo failed");
362: continue;
363: }
364: debug("Connecting to %.200s [%.100s] port %s.",
365: host, ntop, strport);
366:
367: /* Create a socket for connecting. */
1.139 markus 368: sock = ssh_create_socket(needpriv, ai);
1.49 markus 369: if (sock < 0)
1.110 markus 370: /* Any error is already output */
1.49 markus 371: continue;
372:
1.141 djm 373: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
374: options.connection_timeout) >= 0) {
1.49 markus 375: /* Successful connection. */
1.102 markus 376: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 377: break;
1.49 markus 378: } else {
1.110 markus 379: if (errno == ECONNREFUSED)
380: full_failure = 0;
1.131 itojun 381: debug("connect to address %s port %s: %s",
382: ntop, strport, strerror(errno));
1.40 markus 383: /*
384: * Close the failed socket; there appear to
385: * be some problems when reusing a socket for
386: * which connect() has already returned an
387: * error.
388: */
1.38 markus 389: close(sock);
390: }
391: }
1.49 markus 392: if (ai)
393: break; /* Successful connection. */
1.1 deraadt 394:
1.110 markus 395: attempt++;
396: if (attempt >= connection_attempts)
397: break;
1.38 markus 398: /* Sleep a moment before retrying. */
399: sleep(1);
400: }
1.49 markus 401:
402: freeaddrinfo(aitop);
403:
1.38 markus 404: /* Return failure if we didn't get a successful connection. */
1.130 itojun 405: if (attempt >= connection_attempts) {
1.138 itojun 406: logit("ssh: connect to host %s port %s: %s",
1.130 itojun 407: host, strport, strerror(errno));
1.110 markus 408: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.130 itojun 409: }
1.38 markus 410:
411: debug("Connection established.");
1.90 markus 412:
413: /* Set keepalives if requested. */
414: if (options.keepalives &&
415: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
416: sizeof(on)) < 0)
417: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 418:
419: /* Set the connection. */
420: packet_set_connection(sock, sock);
1.1 deraadt 421:
1.110 markus 422: return 0;
1.59 markus 423: }
424:
1.43 markus 425: /*
1.39 deraadt 426: * Waits for the server identification string, and sends our own
427: * identification string.
428: */
1.109 itojun 429: static void
1.95 itojun 430: ssh_exchange_identification(void)
1.1 deraadt 431: {
1.38 markus 432: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 433: int remote_major, remote_minor, i, mismatch;
1.38 markus 434: int connection_in = packet_get_connection_in();
435: int connection_out = packet_get_connection_out();
1.93 stevesk 436: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 437:
438: /* Read other side\'s version identification. */
1.75 markus 439: for (;;) {
440: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 441: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 442: if (len < 0)
443: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
444: if (len != 1)
445: fatal("ssh_exchange_identification: Connection closed by remote host");
446: if (buf[i] == '\r') {
447: buf[i] = '\n';
448: buf[i + 1] = 0;
449: continue; /**XXX wait for \n */
450: }
451: if (buf[i] == '\n') {
452: buf[i + 1] = 0;
453: break;
454: }
1.38 markus 455: }
1.75 markus 456: buf[sizeof(buf) - 1] = 0;
1.76 markus 457: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 458: break;
1.75 markus 459: debug("ssh_exchange_identification: %s", buf);
1.38 markus 460: }
1.59 markus 461: server_version_string = xstrdup(buf);
1.38 markus 462:
1.40 markus 463: /*
464: * Check that the versions match. In future this might accept
465: * several versions and set appropriate flags to handle them.
466: */
1.59 markus 467: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
468: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 469: fatal("Bad remote protocol version identification: '%.100s'", buf);
470: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 471: remote_major, remote_minor, remote_version);
1.38 markus 472:
1.59 markus 473: compat_datafellows(remote_version);
1.64 markus 474: mismatch = 0;
1.59 markus 475:
1.116 deraadt 476: switch (remote_major) {
1.64 markus 477: case 1:
478: if (remote_minor == 99 &&
479: (options.protocol & SSH_PROTO_2) &&
480: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
481: enable_compat20();
482: break;
483: }
484: if (!(options.protocol & SSH_PROTO_1)) {
485: mismatch = 1;
486: break;
487: }
488: if (remote_minor < 3) {
489: fatal("Remote machine has too old SSH software version.");
1.81 markus 490: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 491: /* We speak 1.3, too. */
492: enable_compat13();
1.81 markus 493: minor1 = 3;
1.64 markus 494: if (options.forward_agent) {
1.138 itojun 495: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 496: options.forward_agent = 0;
497: }
498: }
499: break;
500: case 2:
501: if (options.protocol & SSH_PROTO_2) {
502: enable_compat20();
503: break;
1.38 markus 504: }
1.64 markus 505: /* FALLTHROUGH */
1.68 markus 506: default:
1.64 markus 507: mismatch = 1;
508: break;
1.38 markus 509: }
1.64 markus 510: if (mismatch)
1.38 markus 511: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 512: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
513: remote_major);
1.38 markus 514: /* Send our own protocol version identification. */
515: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 516: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 517: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 518: SSH_VERSION);
1.146 deraadt 519: if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 520: fatal("write: %.100s", strerror(errno));
1.59 markus 521: client_version_string = xstrdup(buf);
522: chop(client_version_string);
523: chop(server_version_string);
524: debug("Local version string %.100s", client_version_string);
1.1 deraadt 525: }
526:
1.96 markus 527: /* defaults to 'no' */
1.109 itojun 528: static int
1.112 markus 529: confirm(const char *prompt)
1.1 deraadt 530: {
1.119 markus 531: const char *msg, *again = "Please type 'yes' or 'no': ";
532: char *p;
533: int ret = -1;
1.96 markus 534:
535: if (options.batch_mode)
536: return 0;
1.119 markus 537: for (msg = prompt;;msg = again) {
538: p = read_passphrase(msg, RP_ECHO);
539: if (p == NULL ||
540: (p[0] == '\0') || (p[0] == '\n') ||
541: strncasecmp(p, "no", 2) == 0)
542: ret = 0;
1.127 markus 543: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 544: ret = 1;
545: if (p)
546: xfree(p);
547: if (ret != -1)
548: return ret;
1.1 deraadt 549: }
550: }
551:
1.39 deraadt 552: /*
1.108 markus 553: * check whether the supplied host key is valid, return -1 if the key
554: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 555: */
1.109 itojun 556: static int
1.70 markus 557: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 558: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 559: {
1.58 markus 560: Key *file_key;
1.72 markus 561: char *type = key_type(host_key);
1.46 markus 562: char *ip = NULL;
1.100 markus 563: char hostline[1000], *hostp, *fp;
1.38 markus 564: HostStatus host_status;
565: HostStatus ip_status;
1.49 markus 566: int local = 0, host_ip_differ = 0;
567: char ntop[NI_MAXHOST];
1.119 markus 568: char msg[1024];
1.145 jakob 569: int len, host_line, ip_line;
1.85 markus 570: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 571:
572: /*
573: * Force accepting of the host key for loopback/localhost. The
574: * problem is that if the home directory is NFS-mounted to multiple
575: * machines, localhost will refer to a different machine in each of
576: * them, and the user will get bogus HOST_CHANGED warnings. This
577: * essentially disables host authentication for localhost; however,
578: * this is probably not a real problem.
579: */
1.70 markus 580: /** hostaddr == 0! */
1.49 markus 581: switch (hostaddr->sa_family) {
582: case AF_INET:
1.108 markus 583: local = (ntohl(((struct sockaddr_in *)hostaddr)->
584: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 585: break;
586: case AF_INET6:
1.108 markus 587: local = IN6_IS_ADDR_LOOPBACK(
588: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 589: break;
590: default:
591: local = 0;
592: break;
593: }
1.111 markus 594: if (options.no_host_authentication_for_localhost == 1 && local &&
595: options.host_key_alias == NULL) {
1.88 markus 596: debug("Forcing accepting of host key for "
597: "loopback/localhost.");
1.108 markus 598: return 0;
1.49 markus 599: }
1.42 markus 600:
601: /*
1.88 markus 602: * We don't have the remote ip-address for connections
603: * using a proxy command
1.42 markus 604: */
1.84 markus 605: if (options.proxy_command == NULL) {
606: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 607: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 608: fatal("check_host_key: getnameinfo failed");
609: ip = xstrdup(ntop);
610: } else {
611: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 612: }
1.88 markus 613: /*
614: * Turn off check_host_ip if the connection is to localhost, via proxy
615: * command or if we don't have a hostname to compare with
616: */
617: if (options.check_host_ip &&
618: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
619: options.check_host_ip = 0;
1.86 markus 620:
621: /*
622: * Allow the user to record the key under a different name. This is
623: * useful for ssh tunneling over forwarded connections or if you run
624: * multiple sshd's on different ports on the same machine.
625: */
626: if (options.host_key_alias != NULL) {
627: host = options.host_key_alias;
628: debug("using hostkeyalias: %s", host);
1.84 markus 629: }
1.38 markus 630:
1.46 markus 631: /*
632: * Store the host key from the known host file in here so that we can
633: * compare it with the key for the IP address.
634: */
1.58 markus 635: file_key = key_new(host_key->type);
1.38 markus 636:
1.40 markus 637: /*
638: * Check if the host key is present in the user\'s list of known
639: * hosts or in the systemwide list.
640: */
1.85 markus 641: host_file = user_hostfile;
1.108 markus 642: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 643: file_key, &host_line);
1.85 markus 644: if (host_status == HOST_NEW) {
645: host_file = system_hostfile;
1.108 markus 646: host_status = check_host_in_hostfile(host_file, host, host_key,
647: file_key, &host_line);
1.85 markus 648: }
1.40 markus 649: /*
650: * Also perform check for the ip address, skip the check if we are
651: * localhost or the hostname was an ip address to begin with
652: */
1.88 markus 653: if (options.check_host_ip) {
1.58 markus 654: Key *ip_key = key_new(host_key->type);
1.38 markus 655:
1.85 markus 656: ip_file = user_hostfile;
1.108 markus 657: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
658: ip_key, &ip_line);
1.85 markus 659: if (ip_status == HOST_NEW) {
660: ip_file = system_hostfile;
1.108 markus 661: ip_status = check_host_in_hostfile(ip_file, ip,
662: host_key, ip_key, &ip_line);
1.85 markus 663: }
1.38 markus 664: if (host_status == HOST_CHANGED &&
1.58 markus 665: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 666: host_ip_differ = 1;
667:
1.58 markus 668: key_free(ip_key);
1.38 markus 669: } else
670: ip_status = host_status;
671:
1.58 markus 672: key_free(file_key);
1.38 markus 673:
674: switch (host_status) {
675: case HOST_OK:
676: /* The host is known and the key matches. */
1.72 markus 677: debug("Host '%.200s' is known and matches the %s host key.",
678: host, type);
1.85 markus 679: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 680: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 681: if (readonly)
1.138 itojun 682: logit("%s host key for IP address "
1.108 markus 683: "'%.128s' not in list of known hosts.",
684: type, ip);
685: else if (!add_host_to_hostfile(user_hostfile, ip,
1.118 deraadt 686: host_key))
1.138 itojun 687: logit("Failed to add the %s host key for IP "
1.108 markus 688: "address '%.128s' to the list of known "
689: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 690: else
1.138 itojun 691: logit("Warning: Permanently added the %s host "
1.108 markus 692: "key for IP address '%.128s' to the list "
693: "of known hosts.", type, ip);
1.38 markus 694: }
695: break;
696: case HOST_NEW:
1.108 markus 697: if (readonly)
698: goto fail;
1.38 markus 699: /* The host is new. */
700: if (options.strict_host_key_checking == 1) {
1.108 markus 701: /*
702: * User has requested strict host key checking. We
703: * will not add the host key automatically. The only
704: * alternative left is to abort.
705: */
706: error("No %s host key is known for %.200s and you "
707: "have requested strict checking.", type, host);
708: goto fail;
1.38 markus 709: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 710: char msg1[1024], msg2[1024];
711:
712: if (show_other_keys(host, host_key))
713: snprintf(msg1, sizeof(msg1),
714: "\nbut keys of different type are already"
715: " known for this host.");
716: else
717: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 718: /* The default */
1.100 markus 719: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.145 jakob 720: msg2[0] = '\0';
721: if (options.verify_host_key_dns) {
722: if (verified_host_key_dns)
723: snprintf(msg2, sizeof(msg2),
724: "Matching host key fingerprint"
725: " found in DNS.\n");
726: else
727: snprintf(msg2, sizeof(msg2),
728: "No matching host key fingerprint"
729: " found in DNS.\n");
730: }
1.119 markus 731: snprintf(msg, sizeof(msg),
1.108 markus 732: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 733: "established%s\n"
1.145 jakob 734: "%s key fingerprint is %s.\n%s"
1.108 markus 735: "Are you sure you want to continue connecting "
1.132 markus 736: "(yes/no)? ",
1.145 jakob 737: host, ip, msg1, type, fp, msg2);
1.100 markus 738: xfree(fp);
1.119 markus 739: if (!confirm(msg))
1.108 markus 740: goto fail;
1.38 markus 741: }
1.88 markus 742: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 743: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
744: hostp = hostline;
745: } else
746: hostp = host;
747:
1.108 markus 748: /*
749: * If not in strict mode, add the key automatically to the
750: * local known_hosts file.
751: */
1.70 markus 752: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.138 itojun 753: logit("Failed to add the host to the list of known "
1.108 markus 754: "hosts (%.500s).", user_hostfile);
1.38 markus 755: else
1.138 itojun 756: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 757: "list of known hosts.", hostp, type);
1.38 markus 758: break;
759: case HOST_CHANGED:
760: if (options.check_host_ip && host_ip_differ) {
761: char *msg;
762: if (ip_status == HOST_NEW)
763: msg = "is unknown";
764: else if (ip_status == HOST_OK)
765: msg = "is unchanged";
766: else
767: msg = "has a different value";
768: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
769: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
770: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 771: error("The %s host key for %s has changed,", type, host);
1.38 markus 772: error("and the key for the according IP address %s", ip);
773: error("%s. This could either mean that", msg);
774: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 775: error("and its host key have changed at the same time.");
1.88 markus 776: if (ip_status != HOST_NEW)
1.85 markus 777: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 778: }
779: /* The host key has changed. */
1.100 markus 780: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 781: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 782: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 783: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
784: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
785: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 786: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 787: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.100 markus 788: type, fp);
1.38 markus 789: error("Please contact your system administrator.");
790: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 791: user_hostfile);
1.85 markus 792: error("Offending key in %s:%d", host_file, host_line);
1.100 markus 793: xfree(fp);
1.38 markus 794:
1.40 markus 795: /*
796: * If strict host key checking is in use, the user will have
797: * to edit the key manually and we can only abort.
798: */
1.108 markus 799: if (options.strict_host_key_checking) {
800: error("%s host key for %.200s has changed and you have "
801: "requested strict checking.", type, host);
802: goto fail;
803: }
1.38 markus 804:
1.40 markus 805: /*
806: * If strict host key checking has not been requested, allow
1.144 djm 807: * the connection but without MITM-able authentication or
1.40 markus 808: * agent forwarding.
809: */
1.38 markus 810: if (options.password_authentication) {
1.108 markus 811: error("Password authentication is disabled to avoid "
812: "man-in-the-middle attacks.");
1.38 markus 813: options.password_authentication = 0;
1.144 djm 814: }
815: if (options.kbd_interactive_authentication) {
816: error("Keyboard-interactive authentication is disabled"
817: " to avoid man-in-the-middle attacks.");
818: options.kbd_interactive_authentication = 0;
819: options.challenge_response_authentication = 0;
820: }
821: if (options.challenge_response_authentication) {
822: error("Challenge/response authentication is disabled"
823: " to avoid man-in-the-middle attacks.");
824: options.challenge_response_authentication = 0;
1.38 markus 825: }
826: if (options.forward_agent) {
1.108 markus 827: error("Agent forwarding is disabled to avoid "
828: "man-in-the-middle attacks.");
1.38 markus 829: options.forward_agent = 0;
1.83 markus 830: }
831: if (options.forward_x11) {
1.108 markus 832: error("X11 forwarding is disabled to avoid "
833: "man-in-the-middle attacks.");
1.83 markus 834: options.forward_x11 = 0;
835: }
1.108 markus 836: if (options.num_local_forwards > 0 ||
837: options.num_remote_forwards > 0) {
838: error("Port forwarding is disabled to avoid "
839: "man-in-the-middle attacks.");
840: options.num_local_forwards =
1.118 deraadt 841: options.num_remote_forwards = 0;
1.38 markus 842: }
1.40 markus 843: /*
844: * XXX Should permit the user to change to use the new id.
845: * This could be done by converting the host key to an
846: * identifying sentence, tell that the host identifies itself
847: * by that sentence, and ask the user if he/she whishes to
848: * accept the authentication.
849: */
1.38 markus 850: break;
1.132 markus 851: case HOST_FOUND:
852: fatal("internal error");
853: break;
1.88 markus 854: }
855:
856: if (options.check_host_ip && host_status != HOST_CHANGED &&
857: ip_status == HOST_CHANGED) {
1.119 markus 858: snprintf(msg, sizeof(msg),
859: "Warning: the %s host key for '%.200s' "
860: "differs from the key for the IP address '%.128s'"
861: "\nOffending key for IP in %s:%d",
862: type, host, ip, ip_file, ip_line);
863: if (host_status == HOST_OK) {
864: len = strlen(msg);
865: snprintf(msg + len, sizeof(msg) - len,
866: "\nMatching host key in %s:%d",
1.125 deraadt 867: host_file, host_line);
1.119 markus 868: }
1.88 markus 869: if (options.strict_host_key_checking == 1) {
1.143 djm 870: logit("%s", msg);
1.108 markus 871: error("Exiting, you have requested strict checking.");
872: goto fail;
1.88 markus 873: } else if (options.strict_host_key_checking == 2) {
1.119 markus 874: strlcat(msg, "\nAre you sure you want "
875: "to continue connecting (yes/no)? ", sizeof(msg));
876: if (!confirm(msg))
1.108 markus 877: goto fail;
1.119 markus 878: } else {
1.143 djm 879: logit("%s", msg);
1.88 markus 880: }
1.38 markus 881: }
1.82 provos 882:
883: xfree(ip);
1.108 markus 884: return 0;
885:
886: fail:
887: xfree(ip);
888: return -1;
889: }
890:
1.140 jakob 891: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 892: int
893: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
894: {
895: struct stat st;
1.140 jakob 896:
897: if (options.verify_host_key_dns) {
898: switch(verify_host_key_dns(host, hostaddr, host_key)) {
899: case DNS_VERIFY_OK:
1.145 jakob 900: #ifdef DNSSEC
1.140 jakob 901: return 0;
1.145 jakob 902: #else
903: verified_host_key_dns = 1;
904: break;
905: #endif
1.140 jakob 906: case DNS_VERIFY_FAILED:
907: return -1;
908: case DNS_VERIFY_ERROR:
909: break;
910: default:
911: debug3("bad return value from verify_host_key_dns");
912: break;
913: }
914: }
1.108 markus 915:
916: /* return ok if the key can be found in an old keyfile */
917: if (stat(options.system_hostfile2, &st) == 0 ||
918: stat(options.user_hostfile2, &st) == 0) {
919: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
920: options.user_hostfile2, options.system_hostfile2) == 0)
921: return 0;
922: }
923: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
924: options.user_hostfile, options.system_hostfile);
1.51 markus 925: }
1.70 markus 926:
1.51 markus 927: /*
928: * Starts a dialog with the server, and authenticates the current user on the
929: * server. This does not need any extra privileges. The basic connection
930: * to the server must already have been established before this is called.
931: * If login fails, this function prints an error and never returns.
932: * This function does not require super-user privileges.
933: */
934: void
1.120 markus 935: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 936: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 937: {
938: char *host, *cp;
1.70 markus 939: char *server_user, *local_user;
940:
941: local_user = xstrdup(pw->pw_name);
942: server_user = options.user ? options.user : local_user;
1.51 markus 943:
944: /* Convert the user-supplied hostname into all lowercase. */
945: host = xstrdup(orighost);
946: for (cp = host; *cp; cp++)
947: if (isupper(*cp))
948: *cp = tolower(*cp);
949:
950: /* Exchange protocol version identification strings with the server. */
951: ssh_exchange_identification();
952:
953: /* Put the connection into non-blocking mode. */
954: packet_set_nonblocking();
955:
956: /* key exchange */
957: /* authenticate user */
1.59 markus 958: if (compat20) {
959: ssh_kex2(host, hostaddr);
1.120 markus 960: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 961: } else {
962: ssh_kex(host, hostaddr);
1.120 markus 963: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 964: }
1.97 markus 965: }
966:
967: void
968: ssh_put_password(char *password)
969: {
970: int size;
971: char *padded;
972:
1.99 deraadt 973: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 974: packet_put_cstring(password);
1.99 deraadt 975: return;
976: }
1.97 markus 977: size = roundup(strlen(password) + 1, 32);
978: padded = xmalloc(size);
979: memset(padded, 0, size);
980: strlcpy(padded, password, size);
981: packet_put_string(padded, size);
982: memset(padded, 0, size);
983: xfree(padded);
1.132 markus 984: }
985:
986: static int
987: show_key_from_file(const char *file, const char *host, int keytype)
988: {
989: Key *found;
990: char *fp;
991: int line, ret;
992:
993: found = key_new(keytype);
994: if ((ret = lookup_key_in_hostfile_by_type(file, host,
995: keytype, found, &line))) {
996: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 997: logit("WARNING: %s key found for host %s\n"
1.133 markus 998: "in %s:%d\n"
1.132 markus 999: "%s key fingerprint %s.",
1000: key_type(found), host, file, line,
1001: key_type(found), fp);
1002: xfree(fp);
1003: }
1004: key_free(found);
1005: return (ret);
1006: }
1007:
1008: /* print all known host keys for a given host, but skip keys of given type */
1009: static int
1010: show_other_keys(const char *host, Key *key)
1011: {
1012: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
1013: int i, found = 0;
1014:
1015: for (i = 0; type[i] != -1; i++) {
1016: if (type[i] == key->type)
1017: continue;
1018: if (type[i] != KEY_RSA1 &&
1019: show_key_from_file(options.user_hostfile2, host, type[i])) {
1020: found = 1;
1021: continue;
1022: }
1023: if (type[i] != KEY_RSA1 &&
1024: show_key_from_file(options.system_hostfile2, host, type[i])) {
1025: found = 1;
1026: continue;
1027: }
1028: if (show_key_from_file(options.user_hostfile, host, type[i])) {
1029: found = 1;
1030: continue;
1031: }
1032: if (show_key_from_file(options.system_hostfile, host, type[i])) {
1033: found = 1;
1034: continue;
1035: }
1036: debug2("no key of type %d for host %s", type[i], host);
1037: }
1038: return (found);
1.1 deraadt 1039: }
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