Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.141
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"
1.141 ! djm 16: RCSID("$OpenBSD: sshconnect.c,v 1.140 2003/05/14 18:16:21 jakob 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;
! 224: int fdsetsz, optval, rc;
! 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;
! 256: return (-1);
! 257: case -1:
! 258: /* Select error */
! 259: debug("select: %s", strerror(errno));
! 260: return (-1);
! 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));
! 268: return (-1);
! 269: if (optval != 0) {
! 270: errno = optval;
! 271: return (-1);
! 272: }
! 273: break;
! 274: default:
! 275: /* Should not occur */
! 276: fatal("Bogus return (%d) from select()", rc);
! 277: }
! 278:
! 279: return (0);
! 280: }
! 281:
1.39 deraadt 282: /*
1.49 markus 283: * Opens a TCP/IP connection to the remote server on the given host.
284: * The address of the remote host will be returned in hostaddr.
1.124 markus 285: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 286: * a privileged port will be allocated to make the connection.
1.124 markus 287: * This requires super-user privileges if needpriv is true.
1.39 deraadt 288: * Connection_attempts specifies the maximum number of tries (one per
289: * second). If proxy_command is non-NULL, it specifies the command (with %h
290: * and %p substituted for host and port, respectively) to use to contact
291: * the daemon.
1.110 markus 292: * Return values:
293: * 0 for OK
294: * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
295: * ECONNABORTED if we failed without a "Connection refused"
296: * Suitable error messages for the connection failure will already have been
297: * printed.
1.39 deraadt 298: */
1.38 markus 299: int
1.49 markus 300: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 301: u_short port, int family, int connection_attempts,
1.124 markus 302: int needpriv, const char *proxy_command)
1.1 deraadt 303: {
1.90 markus 304: int gaierr;
305: int on = 1;
1.49 markus 306: int sock = -1, attempt;
1.90 markus 307: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 308: struct addrinfo hints, *ai, *aitop;
1.90 markus 309: struct servent *sp;
1.110 markus 310: /*
311: * Did we get only other errors than "Connection refused" (which
312: * should block fallback to rsh and similar), or did we get at least
313: * one "Connection refused"?
314: */
315: int full_failure = 1;
1.38 markus 316:
1.136 markus 317: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 318:
319: /* Get default port if port has not been set. */
320: if (port == 0) {
321: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
322: if (sp)
323: port = ntohs(sp->s_port);
324: else
325: port = SSH_DEFAULT_PORT;
326: }
327: /* If a proxy command is given, connect using it. */
328: if (proxy_command != NULL)
1.124 markus 329: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 330:
331: /* No proxy command. */
332:
1.49 markus 333: memset(&hints, 0, sizeof(hints));
1.115 markus 334: hints.ai_family = family;
1.49 markus 335: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 336: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 337: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 338: fatal("%s: %.100s: %s", __progname, host,
339: gai_strerror(gaierr));
1.38 markus 340:
1.46 markus 341: /*
342: * Try to connect several times. On some machines, the first time
343: * will sometimes fail. In general socket code appears to behave
344: * quite magically on many machines.
1.110 markus 345: */
346: for (attempt = 0; ;) {
1.38 markus 347: if (attempt > 0)
348: debug("Trying again...");
349:
1.49 markus 350: /* Loop through addresses for this host, and try each one in
1.68 markus 351: sequence until the connection succeeds. */
1.49 markus 352: for (ai = aitop; ai; ai = ai->ai_next) {
353: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
354: continue;
355: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
356: ntop, sizeof(ntop), strport, sizeof(strport),
357: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
358: error("ssh_connect: getnameinfo failed");
359: continue;
360: }
361: debug("Connecting to %.200s [%.100s] port %s.",
362: host, ntop, strport);
363:
364: /* Create a socket for connecting. */
1.139 markus 365: sock = ssh_create_socket(needpriv, ai);
1.49 markus 366: if (sock < 0)
1.110 markus 367: /* Any error is already output */
1.49 markus 368: continue;
369:
1.141 ! djm 370: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
! 371: options.connection_timeout) >= 0) {
1.49 markus 372: /* Successful connection. */
1.102 markus 373: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 374: break;
1.49 markus 375: } else {
1.110 markus 376: if (errno == ECONNREFUSED)
377: full_failure = 0;
1.131 itojun 378: debug("connect to address %s port %s: %s",
379: ntop, strport, strerror(errno));
1.40 markus 380: /*
381: * Close the failed socket; there appear to
382: * be some problems when reusing a socket for
383: * which connect() has already returned an
384: * error.
385: */
1.38 markus 386: close(sock);
387: }
388: }
1.49 markus 389: if (ai)
390: break; /* Successful connection. */
1.1 deraadt 391:
1.110 markus 392: attempt++;
393: if (attempt >= connection_attempts)
394: break;
1.38 markus 395: /* Sleep a moment before retrying. */
396: sleep(1);
397: }
1.49 markus 398:
399: freeaddrinfo(aitop);
400:
1.38 markus 401: /* Return failure if we didn't get a successful connection. */
1.130 itojun 402: if (attempt >= connection_attempts) {
1.138 itojun 403: logit("ssh: connect to host %s port %s: %s",
1.130 itojun 404: host, strport, strerror(errno));
1.110 markus 405: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.130 itojun 406: }
1.38 markus 407:
408: debug("Connection established.");
1.90 markus 409:
410: /* Set keepalives if requested. */
411: if (options.keepalives &&
412: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
413: sizeof(on)) < 0)
414: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 415:
416: /* Set the connection. */
417: packet_set_connection(sock, sock);
1.1 deraadt 418:
1.110 markus 419: return 0;
1.59 markus 420: }
421:
1.43 markus 422: /*
1.39 deraadt 423: * Waits for the server identification string, and sends our own
424: * identification string.
425: */
1.109 itojun 426: static void
1.95 itojun 427: ssh_exchange_identification(void)
1.1 deraadt 428: {
1.38 markus 429: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 430: int remote_major, remote_minor, i, mismatch;
1.38 markus 431: int connection_in = packet_get_connection_in();
432: int connection_out = packet_get_connection_out();
1.93 stevesk 433: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 434:
435: /* Read other side\'s version identification. */
1.75 markus 436: for (;;) {
437: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 438: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 439: if (len < 0)
440: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
441: if (len != 1)
442: fatal("ssh_exchange_identification: Connection closed by remote host");
443: if (buf[i] == '\r') {
444: buf[i] = '\n';
445: buf[i + 1] = 0;
446: continue; /**XXX wait for \n */
447: }
448: if (buf[i] == '\n') {
449: buf[i + 1] = 0;
450: break;
451: }
1.38 markus 452: }
1.75 markus 453: buf[sizeof(buf) - 1] = 0;
1.76 markus 454: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 455: break;
1.75 markus 456: debug("ssh_exchange_identification: %s", buf);
1.38 markus 457: }
1.59 markus 458: server_version_string = xstrdup(buf);
1.38 markus 459:
1.40 markus 460: /*
461: * Check that the versions match. In future this might accept
462: * several versions and set appropriate flags to handle them.
463: */
1.59 markus 464: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
465: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 466: fatal("Bad remote protocol version identification: '%.100s'", buf);
467: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 468: remote_major, remote_minor, remote_version);
1.38 markus 469:
1.59 markus 470: compat_datafellows(remote_version);
1.64 markus 471: mismatch = 0;
1.59 markus 472:
1.116 deraadt 473: switch (remote_major) {
1.64 markus 474: case 1:
475: if (remote_minor == 99 &&
476: (options.protocol & SSH_PROTO_2) &&
477: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
478: enable_compat20();
479: break;
480: }
481: if (!(options.protocol & SSH_PROTO_1)) {
482: mismatch = 1;
483: break;
484: }
485: if (remote_minor < 3) {
486: fatal("Remote machine has too old SSH software version.");
1.81 markus 487: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 488: /* We speak 1.3, too. */
489: enable_compat13();
1.81 markus 490: minor1 = 3;
1.64 markus 491: if (options.forward_agent) {
1.138 itojun 492: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 493: options.forward_agent = 0;
494: }
495: }
496: break;
497: case 2:
498: if (options.protocol & SSH_PROTO_2) {
499: enable_compat20();
500: break;
1.38 markus 501: }
1.64 markus 502: /* FALLTHROUGH */
1.68 markus 503: default:
1.64 markus 504: mismatch = 1;
505: break;
1.38 markus 506: }
1.64 markus 507: if (mismatch)
1.38 markus 508: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 509: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
510: remote_major);
1.38 markus 511: /* Send our own protocol version identification. */
512: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 513: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 514: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 515: SSH_VERSION);
1.45 deraadt 516: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 517: fatal("write: %.100s", strerror(errno));
1.59 markus 518: client_version_string = xstrdup(buf);
519: chop(client_version_string);
520: chop(server_version_string);
521: debug("Local version string %.100s", client_version_string);
1.1 deraadt 522: }
523:
1.96 markus 524: /* defaults to 'no' */
1.109 itojun 525: static int
1.112 markus 526: confirm(const char *prompt)
1.1 deraadt 527: {
1.119 markus 528: const char *msg, *again = "Please type 'yes' or 'no': ";
529: char *p;
530: int ret = -1;
1.96 markus 531:
532: if (options.batch_mode)
533: return 0;
1.119 markus 534: for (msg = prompt;;msg = again) {
535: p = read_passphrase(msg, RP_ECHO);
536: if (p == NULL ||
537: (p[0] == '\0') || (p[0] == '\n') ||
538: strncasecmp(p, "no", 2) == 0)
539: ret = 0;
1.127 markus 540: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 541: ret = 1;
542: if (p)
543: xfree(p);
544: if (ret != -1)
545: return ret;
1.1 deraadt 546: }
547: }
548:
1.39 deraadt 549: /*
1.108 markus 550: * check whether the supplied host key is valid, return -1 if the key
551: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 552: */
1.109 itojun 553: static int
1.70 markus 554: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 555: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 556: {
1.58 markus 557: Key *file_key;
1.72 markus 558: char *type = key_type(host_key);
1.46 markus 559: char *ip = NULL;
1.100 markus 560: char hostline[1000], *hostp, *fp;
1.38 markus 561: HostStatus host_status;
562: HostStatus ip_status;
1.49 markus 563: int local = 0, host_ip_differ = 0;
564: char ntop[NI_MAXHOST];
1.119 markus 565: char msg[1024];
1.132 markus 566: int len, host_line, ip_line, has_keys;
1.85 markus 567: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 568:
569: /*
570: * Force accepting of the host key for loopback/localhost. The
571: * problem is that if the home directory is NFS-mounted to multiple
572: * machines, localhost will refer to a different machine in each of
573: * them, and the user will get bogus HOST_CHANGED warnings. This
574: * essentially disables host authentication for localhost; however,
575: * this is probably not a real problem.
576: */
1.70 markus 577: /** hostaddr == 0! */
1.49 markus 578: switch (hostaddr->sa_family) {
579: case AF_INET:
1.108 markus 580: local = (ntohl(((struct sockaddr_in *)hostaddr)->
581: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 582: break;
583: case AF_INET6:
1.108 markus 584: local = IN6_IS_ADDR_LOOPBACK(
585: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 586: break;
587: default:
588: local = 0;
589: break;
590: }
1.111 markus 591: if (options.no_host_authentication_for_localhost == 1 && local &&
592: options.host_key_alias == NULL) {
1.88 markus 593: debug("Forcing accepting of host key for "
594: "loopback/localhost.");
1.108 markus 595: return 0;
1.49 markus 596: }
1.42 markus 597:
598: /*
1.88 markus 599: * We don't have the remote ip-address for connections
600: * using a proxy command
1.42 markus 601: */
1.84 markus 602: if (options.proxy_command == NULL) {
603: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 604: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 605: fatal("check_host_key: getnameinfo failed");
606: ip = xstrdup(ntop);
607: } else {
608: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 609: }
1.88 markus 610: /*
611: * Turn off check_host_ip if the connection is to localhost, via proxy
612: * command or if we don't have a hostname to compare with
613: */
614: if (options.check_host_ip &&
615: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
616: options.check_host_ip = 0;
1.86 markus 617:
618: /*
619: * Allow the user to record the key under a different name. This is
620: * useful for ssh tunneling over forwarded connections or if you run
621: * multiple sshd's on different ports on the same machine.
622: */
623: if (options.host_key_alias != NULL) {
624: host = options.host_key_alias;
625: debug("using hostkeyalias: %s", host);
1.84 markus 626: }
1.38 markus 627:
1.46 markus 628: /*
629: * Store the host key from the known host file in here so that we can
630: * compare it with the key for the IP address.
631: */
1.58 markus 632: file_key = key_new(host_key->type);
1.38 markus 633:
1.40 markus 634: /*
635: * Check if the host key is present in the user\'s list of known
636: * hosts or in the systemwide list.
637: */
1.85 markus 638: host_file = user_hostfile;
1.108 markus 639: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 640: file_key, &host_line);
1.85 markus 641: if (host_status == HOST_NEW) {
642: host_file = system_hostfile;
1.108 markus 643: host_status = check_host_in_hostfile(host_file, host, host_key,
644: file_key, &host_line);
1.85 markus 645: }
1.40 markus 646: /*
647: * Also perform check for the ip address, skip the check if we are
648: * localhost or the hostname was an ip address to begin with
649: */
1.88 markus 650: if (options.check_host_ip) {
1.58 markus 651: Key *ip_key = key_new(host_key->type);
1.38 markus 652:
1.85 markus 653: ip_file = user_hostfile;
1.108 markus 654: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
655: ip_key, &ip_line);
1.85 markus 656: if (ip_status == HOST_NEW) {
657: ip_file = system_hostfile;
1.108 markus 658: ip_status = check_host_in_hostfile(ip_file, ip,
659: host_key, ip_key, &ip_line);
1.85 markus 660: }
1.38 markus 661: if (host_status == HOST_CHANGED &&
1.58 markus 662: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 663: host_ip_differ = 1;
664:
1.58 markus 665: key_free(ip_key);
1.38 markus 666: } else
667: ip_status = host_status;
668:
1.58 markus 669: key_free(file_key);
1.38 markus 670:
671: switch (host_status) {
672: case HOST_OK:
673: /* The host is known and the key matches. */
1.72 markus 674: debug("Host '%.200s' is known and matches the %s host key.",
675: host, type);
1.85 markus 676: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 677: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 678: if (readonly)
1.138 itojun 679: logit("%s host key for IP address "
1.108 markus 680: "'%.128s' not in list of known hosts.",
681: type, ip);
682: else if (!add_host_to_hostfile(user_hostfile, ip,
1.118 deraadt 683: host_key))
1.138 itojun 684: logit("Failed to add the %s host key for IP "
1.108 markus 685: "address '%.128s' to the list of known "
686: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 687: else
1.138 itojun 688: logit("Warning: Permanently added the %s host "
1.108 markus 689: "key for IP address '%.128s' to the list "
690: "of known hosts.", type, ip);
1.38 markus 691: }
692: break;
693: case HOST_NEW:
1.108 markus 694: if (readonly)
695: goto fail;
1.38 markus 696: /* The host is new. */
697: if (options.strict_host_key_checking == 1) {
1.108 markus 698: /*
699: * User has requested strict host key checking. We
700: * will not add the host key automatically. The only
701: * alternative left is to abort.
702: */
703: error("No %s host key is known for %.200s and you "
704: "have requested strict checking.", type, host);
705: goto fail;
1.38 markus 706: } else if (options.strict_host_key_checking == 2) {
1.132 markus 707: has_keys = show_other_keys(host, host_key);
1.38 markus 708: /* The default */
1.100 markus 709: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.119 markus 710: snprintf(msg, sizeof(msg),
1.108 markus 711: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 712: "established%s\n"
1.72 markus 713: "%s key fingerprint is %s.\n"
1.108 markus 714: "Are you sure you want to continue connecting "
1.132 markus 715: "(yes/no)? ",
1.137 deraadt 716: host, ip,
717: has_keys ? ",\nbut keys of different type are already "
718: "known for this host." : ".",
719: type, fp);
1.100 markus 720: xfree(fp);
1.119 markus 721: if (!confirm(msg))
1.108 markus 722: goto fail;
1.38 markus 723: }
1.88 markus 724: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 725: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
726: hostp = hostline;
727: } else
728: hostp = host;
729:
1.108 markus 730: /*
731: * If not in strict mode, add the key automatically to the
732: * local known_hosts file.
733: */
1.70 markus 734: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.138 itojun 735: logit("Failed to add the host to the list of known "
1.108 markus 736: "hosts (%.500s).", user_hostfile);
1.38 markus 737: else
1.138 itojun 738: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 739: "list of known hosts.", hostp, type);
1.38 markus 740: break;
741: case HOST_CHANGED:
742: if (options.check_host_ip && host_ip_differ) {
743: char *msg;
744: if (ip_status == HOST_NEW)
745: msg = "is unknown";
746: else if (ip_status == HOST_OK)
747: msg = "is unchanged";
748: else
749: msg = "has a different value";
750: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
751: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
752: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 753: error("The %s host key for %s has changed,", type, host);
1.38 markus 754: error("and the key for the according IP address %s", ip);
755: error("%s. This could either mean that", msg);
756: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 757: error("and its host key have changed at the same time.");
1.88 markus 758: if (ip_status != HOST_NEW)
1.85 markus 759: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 760: }
761: /* The host key has changed. */
1.100 markus 762: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 763: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 764: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 765: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
766: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
767: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 768: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 769: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.100 markus 770: type, fp);
1.38 markus 771: error("Please contact your system administrator.");
772: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 773: user_hostfile);
1.85 markus 774: error("Offending key in %s:%d", host_file, host_line);
1.100 markus 775: xfree(fp);
1.38 markus 776:
1.40 markus 777: /*
778: * If strict host key checking is in use, the user will have
779: * to edit the key manually and we can only abort.
780: */
1.108 markus 781: if (options.strict_host_key_checking) {
782: error("%s host key for %.200s has changed and you have "
783: "requested strict checking.", type, host);
784: goto fail;
785: }
1.38 markus 786:
1.40 markus 787: /*
788: * If strict host key checking has not been requested, allow
789: * the connection but without password authentication or
790: * agent forwarding.
791: */
1.38 markus 792: if (options.password_authentication) {
1.108 markus 793: error("Password authentication is disabled to avoid "
794: "man-in-the-middle attacks.");
1.38 markus 795: options.password_authentication = 0;
796: }
797: if (options.forward_agent) {
1.108 markus 798: error("Agent forwarding is disabled to avoid "
799: "man-in-the-middle attacks.");
1.38 markus 800: options.forward_agent = 0;
1.83 markus 801: }
802: if (options.forward_x11) {
1.108 markus 803: error("X11 forwarding is disabled to avoid "
804: "man-in-the-middle attacks.");
1.83 markus 805: options.forward_x11 = 0;
806: }
1.108 markus 807: if (options.num_local_forwards > 0 ||
808: options.num_remote_forwards > 0) {
809: error("Port forwarding is disabled to avoid "
810: "man-in-the-middle attacks.");
811: options.num_local_forwards =
1.118 deraadt 812: options.num_remote_forwards = 0;
1.38 markus 813: }
1.40 markus 814: /*
815: * XXX Should permit the user to change to use the new id.
816: * This could be done by converting the host key to an
817: * identifying sentence, tell that the host identifies itself
818: * by that sentence, and ask the user if he/she whishes to
819: * accept the authentication.
820: */
1.38 markus 821: break;
1.132 markus 822: case HOST_FOUND:
823: fatal("internal error");
824: break;
1.88 markus 825: }
826:
827: if (options.check_host_ip && host_status != HOST_CHANGED &&
828: ip_status == HOST_CHANGED) {
1.119 markus 829: snprintf(msg, sizeof(msg),
830: "Warning: the %s host key for '%.200s' "
831: "differs from the key for the IP address '%.128s'"
832: "\nOffending key for IP in %s:%d",
833: type, host, ip, ip_file, ip_line);
834: if (host_status == HOST_OK) {
835: len = strlen(msg);
836: snprintf(msg + len, sizeof(msg) - len,
837: "\nMatching host key in %s:%d",
1.125 deraadt 838: host_file, host_line);
1.119 markus 839: }
1.88 markus 840: if (options.strict_host_key_checking == 1) {
1.138 itojun 841: logit(msg);
1.108 markus 842: error("Exiting, you have requested strict checking.");
843: goto fail;
1.88 markus 844: } else if (options.strict_host_key_checking == 2) {
1.119 markus 845: strlcat(msg, "\nAre you sure you want "
846: "to continue connecting (yes/no)? ", sizeof(msg));
847: if (!confirm(msg))
1.108 markus 848: goto fail;
1.119 markus 849: } else {
1.138 itojun 850: logit(msg);
1.88 markus 851: }
1.38 markus 852: }
1.82 provos 853:
854: xfree(ip);
1.108 markus 855: return 0;
856:
857: fail:
858: xfree(ip);
859: return -1;
860: }
861:
1.140 jakob 862: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 863: int
864: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
865: {
866: struct stat st;
1.140 jakob 867:
868: #ifdef DNS
869: if (options.verify_host_key_dns) {
870: switch(verify_host_key_dns(host, hostaddr, host_key)) {
871: case DNS_VERIFY_OK:
872: return 0;
873: case DNS_VERIFY_FAILED:
874: return -1;
875: case DNS_VERIFY_ERROR:
876: break;
877: default:
878: debug3("bad return value from verify_host_key_dns");
879: break;
880: }
881: }
882: #endif /* DNS */
1.108 markus 883:
884: /* return ok if the key can be found in an old keyfile */
885: if (stat(options.system_hostfile2, &st) == 0 ||
886: stat(options.user_hostfile2, &st) == 0) {
887: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
888: options.user_hostfile2, options.system_hostfile2) == 0)
889: return 0;
890: }
891: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
892: options.user_hostfile, options.system_hostfile);
1.51 markus 893: }
1.70 markus 894:
1.51 markus 895: /*
896: * Starts a dialog with the server, and authenticates the current user on the
897: * server. This does not need any extra privileges. The basic connection
898: * to the server must already have been established before this is called.
899: * If login fails, this function prints an error and never returns.
900: * This function does not require super-user privileges.
901: */
902: void
1.120 markus 903: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 904: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 905: {
906: char *host, *cp;
1.70 markus 907: char *server_user, *local_user;
908:
909: local_user = xstrdup(pw->pw_name);
910: server_user = options.user ? options.user : local_user;
1.51 markus 911:
912: /* Convert the user-supplied hostname into all lowercase. */
913: host = xstrdup(orighost);
914: for (cp = host; *cp; cp++)
915: if (isupper(*cp))
916: *cp = tolower(*cp);
917:
918: /* Exchange protocol version identification strings with the server. */
919: ssh_exchange_identification();
920:
921: /* Put the connection into non-blocking mode. */
922: packet_set_nonblocking();
923:
924: /* key exchange */
925: /* authenticate user */
1.59 markus 926: if (compat20) {
927: ssh_kex2(host, hostaddr);
1.120 markus 928: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 929: } else {
930: ssh_kex(host, hostaddr);
1.120 markus 931: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 932: }
1.97 markus 933: }
934:
935: void
936: ssh_put_password(char *password)
937: {
938: int size;
939: char *padded;
940:
1.99 deraadt 941: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 942: packet_put_cstring(password);
1.99 deraadt 943: return;
944: }
1.97 markus 945: size = roundup(strlen(password) + 1, 32);
946: padded = xmalloc(size);
947: memset(padded, 0, size);
948: strlcpy(padded, password, size);
949: packet_put_string(padded, size);
950: memset(padded, 0, size);
951: xfree(padded);
1.132 markus 952: }
953:
954: static int
955: show_key_from_file(const char *file, const char *host, int keytype)
956: {
957: Key *found;
958: char *fp;
959: int line, ret;
960:
961: found = key_new(keytype);
962: if ((ret = lookup_key_in_hostfile_by_type(file, host,
963: keytype, found, &line))) {
964: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 965: logit("WARNING: %s key found for host %s\n"
1.133 markus 966: "in %s:%d\n"
1.132 markus 967: "%s key fingerprint %s.",
968: key_type(found), host, file, line,
969: key_type(found), fp);
970: xfree(fp);
971: }
972: key_free(found);
973: return (ret);
974: }
975:
976: /* print all known host keys for a given host, but skip keys of given type */
977: static int
978: show_other_keys(const char *host, Key *key)
979: {
980: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
981: int i, found = 0;
982:
983: for (i = 0; type[i] != -1; i++) {
984: if (type[i] == key->type)
985: continue;
986: if (type[i] != KEY_RSA1 &&
987: show_key_from_file(options.user_hostfile2, host, type[i])) {
988: found = 1;
989: continue;
990: }
991: if (type[i] != KEY_RSA1 &&
992: show_key_from_file(options.system_hostfile2, host, type[i])) {
993: found = 1;
994: continue;
995: }
996: if (show_key_from_file(options.user_hostfile, host, type[i])) {
997: found = 1;
998: continue;
999: }
1000: if (show_key_from_file(options.system_hostfile, host, type[i])) {
1001: found = 1;
1002: continue;
1003: }
1004: debug2("no key of type %d for host %s", type[i], host);
1005: }
1006: return (found);
1.1 deraadt 1007: }