Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.160
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"
1.160 ! djm 16: RCSID("$OpenBSD: sshconnect.c,v 1.159 2005/01/05 08:51:32 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"
1.51 markus 34:
1.140 jakob 35: #include "dns.h"
36:
1.70 markus 37: char *client_version_string = NULL;
38: char *server_version_string = NULL;
1.59 markus 39:
1.153 jakob 40: int matching_host_key_dns = 0;
1.145 jakob 41:
1.124 markus 42: /* import */
1.43 markus 43: extern Options options;
1.50 markus 44: extern char *__progname;
1.124 markus 45: extern uid_t original_real_uid;
46: extern uid_t original_effective_uid;
1.135 djm 47: extern pid_t proxy_command_pid;
1.91 markus 48:
1.132 markus 49: static int show_other_keys(const char *, Key *);
1.150 jakob 50: static void warn_changed_key(Key *);
1.132 markus 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: *
1.154 djm 72: * Use "exec" to avoid "sh -c" processes on some platforms
1.135 djm 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:
1.156 djm 229: set_nonblock(sockfd);
1.141 djm 230: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 231: if (rc == 0) {
232: unset_nonblock(sockfd);
1.141 djm 233: return (0);
1.156 djm 234: }
1.141 djm 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 */
1.154 djm 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);
1.154 djm 265: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 266: &optlen) == -1) {
1.154 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;
1.156 djm 275: unset_nonblock(sockfd);
1.141 djm 276: break;
277: default:
278: /* Should not occur */
279: fatal("Bogus return (%d) from select()", rc);
280: }
281:
1.142 djm 282: xfree(fdset);
283: return (result);
1.141 djm 284: }
285:
1.39 deraadt 286: /*
1.49 markus 287: * Opens a TCP/IP connection to the remote server on the given host.
288: * The address of the remote host will be returned in hostaddr.
1.124 markus 289: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 290: * a privileged port will be allocated to make the connection.
1.124 markus 291: * This requires super-user privileges if needpriv is true.
1.39 deraadt 292: * Connection_attempts specifies the maximum number of tries (one per
293: * second). If proxy_command is non-NULL, it specifies the command (with %h
294: * and %p substituted for host and port, respectively) to use to contact
295: * the daemon.
296: */
1.38 markus 297: int
1.49 markus 298: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 299: u_short port, int family, int connection_attempts,
1.124 markus 300: int needpriv, const char *proxy_command)
1.1 deraadt 301: {
1.90 markus 302: int gaierr;
303: int on = 1;
1.49 markus 304: int sock = -1, attempt;
1.90 markus 305: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 306: struct addrinfo hints, *ai, *aitop;
1.90 markus 307: struct servent *sp;
1.38 markus 308:
1.136 markus 309: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 310:
311: /* Get default port if port has not been set. */
312: if (port == 0) {
313: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
314: if (sp)
315: port = ntohs(sp->s_port);
316: else
317: port = SSH_DEFAULT_PORT;
318: }
319: /* If a proxy command is given, connect using it. */
320: if (proxy_command != NULL)
1.124 markus 321: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 322:
323: /* No proxy command. */
324:
1.49 markus 325: memset(&hints, 0, sizeof(hints));
1.115 markus 326: hints.ai_family = family;
1.49 markus 327: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 328: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 329: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 330: fatal("%s: %.100s: %s", __progname, host,
331: gai_strerror(gaierr));
1.38 markus 332:
1.46 markus 333: /*
334: * Try to connect several times. On some machines, the first time
335: * will sometimes fail. In general socket code appears to behave
336: * quite magically on many machines.
1.110 markus 337: */
338: for (attempt = 0; ;) {
1.38 markus 339: if (attempt > 0)
340: debug("Trying again...");
341:
1.49 markus 342: /* Loop through addresses for this host, and try each one in
1.68 markus 343: sequence until the connection succeeds. */
1.49 markus 344: for (ai = aitop; ai; ai = ai->ai_next) {
345: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
346: continue;
347: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
348: ntop, sizeof(ntop), strport, sizeof(strport),
349: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
350: error("ssh_connect: getnameinfo failed");
351: continue;
352: }
353: debug("Connecting to %.200s [%.100s] port %s.",
354: host, ntop, strport);
355:
356: /* Create a socket for connecting. */
1.139 markus 357: sock = ssh_create_socket(needpriv, ai);
1.49 markus 358: if (sock < 0)
1.110 markus 359: /* Any error is already output */
1.49 markus 360: continue;
361:
1.141 djm 362: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
363: options.connection_timeout) >= 0) {
1.49 markus 364: /* Successful connection. */
1.102 markus 365: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 366: break;
1.49 markus 367: } else {
1.131 itojun 368: debug("connect to address %s port %s: %s",
369: ntop, strport, strerror(errno));
1.40 markus 370: /*
371: * Close the failed socket; there appear to
372: * be some problems when reusing a socket for
373: * which connect() has already returned an
374: * error.
375: */
1.38 markus 376: close(sock);
377: }
378: }
1.49 markus 379: if (ai)
380: break; /* Successful connection. */
1.1 deraadt 381:
1.110 markus 382: attempt++;
383: if (attempt >= connection_attempts)
384: break;
1.38 markus 385: /* Sleep a moment before retrying. */
386: sleep(1);
387: }
1.49 markus 388:
389: freeaddrinfo(aitop);
390:
1.38 markus 391: /* Return failure if we didn't get a successful connection. */
1.130 itojun 392: if (attempt >= connection_attempts) {
1.159 markus 393: error("ssh: connect to host %s port %s: %s",
1.130 itojun 394: host, strport, strerror(errno));
1.159 markus 395: return (-1);
1.130 itojun 396: }
1.38 markus 397:
398: debug("Connection established.");
1.90 markus 399:
1.155 markus 400: /* Set SO_KEEPALIVE if requested. */
401: if (options.tcp_keep_alive &&
1.90 markus 402: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
403: sizeof(on)) < 0)
404: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 405:
406: /* Set the connection. */
407: packet_set_connection(sock, sock);
1.1 deraadt 408:
1.110 markus 409: return 0;
1.59 markus 410: }
411:
1.43 markus 412: /*
1.39 deraadt 413: * Waits for the server identification string, and sends our own
414: * identification string.
415: */
1.109 itojun 416: static void
1.95 itojun 417: ssh_exchange_identification(void)
1.1 deraadt 418: {
1.38 markus 419: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 420: int remote_major, remote_minor, i, mismatch;
1.38 markus 421: int connection_in = packet_get_connection_in();
422: int connection_out = packet_get_connection_out();
1.93 stevesk 423: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 424:
425: /* Read other side\'s version identification. */
1.75 markus 426: for (;;) {
427: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 428: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 429: if (len < 0)
430: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
431: if (len != 1)
432: fatal("ssh_exchange_identification: Connection closed by remote host");
433: if (buf[i] == '\r') {
434: buf[i] = '\n';
435: buf[i + 1] = 0;
436: continue; /**XXX wait for \n */
437: }
438: if (buf[i] == '\n') {
439: buf[i + 1] = 0;
440: break;
441: }
1.38 markus 442: }
1.75 markus 443: buf[sizeof(buf) - 1] = 0;
1.76 markus 444: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 445: break;
1.75 markus 446: debug("ssh_exchange_identification: %s", buf);
1.38 markus 447: }
1.59 markus 448: server_version_string = xstrdup(buf);
1.38 markus 449:
1.40 markus 450: /*
451: * Check that the versions match. In future this might accept
452: * several versions and set appropriate flags to handle them.
453: */
1.59 markus 454: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
455: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 456: fatal("Bad remote protocol version identification: '%.100s'", buf);
457: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 458: remote_major, remote_minor, remote_version);
1.38 markus 459:
1.59 markus 460: compat_datafellows(remote_version);
1.64 markus 461: mismatch = 0;
1.59 markus 462:
1.116 deraadt 463: switch (remote_major) {
1.64 markus 464: case 1:
465: if (remote_minor == 99 &&
466: (options.protocol & SSH_PROTO_2) &&
467: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
468: enable_compat20();
469: break;
470: }
471: if (!(options.protocol & SSH_PROTO_1)) {
472: mismatch = 1;
473: break;
474: }
475: if (remote_minor < 3) {
476: fatal("Remote machine has too old SSH software version.");
1.81 markus 477: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 478: /* We speak 1.3, too. */
479: enable_compat13();
1.81 markus 480: minor1 = 3;
1.64 markus 481: if (options.forward_agent) {
1.138 itojun 482: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 483: options.forward_agent = 0;
484: }
485: }
486: break;
487: case 2:
488: if (options.protocol & SSH_PROTO_2) {
489: enable_compat20();
490: break;
1.38 markus 491: }
1.64 markus 492: /* FALLTHROUGH */
1.68 markus 493: default:
1.64 markus 494: mismatch = 1;
495: break;
1.38 markus 496: }
1.64 markus 497: if (mismatch)
1.38 markus 498: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 499: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
500: remote_major);
1.38 markus 501: /* Send our own protocol version identification. */
502: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 503: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 504: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 505: SSH_VERSION);
1.146 deraadt 506: if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 507: fatal("write: %.100s", strerror(errno));
1.59 markus 508: client_version_string = xstrdup(buf);
509: chop(client_version_string);
510: chop(server_version_string);
511: debug("Local version string %.100s", client_version_string);
1.1 deraadt 512: }
513:
1.96 markus 514: /* defaults to 'no' */
1.109 itojun 515: static int
1.112 markus 516: confirm(const char *prompt)
1.1 deraadt 517: {
1.119 markus 518: const char *msg, *again = "Please type 'yes' or 'no': ";
519: char *p;
520: int ret = -1;
1.96 markus 521:
522: if (options.batch_mode)
523: return 0;
1.119 markus 524: for (msg = prompt;;msg = again) {
525: p = read_passphrase(msg, RP_ECHO);
526: if (p == NULL ||
527: (p[0] == '\0') || (p[0] == '\n') ||
528: strncasecmp(p, "no", 2) == 0)
529: ret = 0;
1.127 markus 530: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 531: ret = 1;
532: if (p)
533: xfree(p);
534: if (ret != -1)
535: return ret;
1.1 deraadt 536: }
537: }
538:
1.39 deraadt 539: /*
1.108 markus 540: * check whether the supplied host key is valid, return -1 if the key
541: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 542: */
1.109 itojun 543: static int
1.70 markus 544: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 545: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 546: {
1.58 markus 547: Key *file_key;
1.152 jakob 548: const char *type = key_type(host_key);
1.46 markus 549: char *ip = NULL;
1.100 markus 550: char hostline[1000], *hostp, *fp;
1.38 markus 551: HostStatus host_status;
552: HostStatus ip_status;
1.49 markus 553: int local = 0, host_ip_differ = 0;
554: char ntop[NI_MAXHOST];
1.119 markus 555: char msg[1024];
1.145 jakob 556: int len, host_line, ip_line;
1.85 markus 557: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 558:
559: /*
560: * Force accepting of the host key for loopback/localhost. The
561: * problem is that if the home directory is NFS-mounted to multiple
562: * machines, localhost will refer to a different machine in each of
563: * them, and the user will get bogus HOST_CHANGED warnings. This
564: * essentially disables host authentication for localhost; however,
565: * this is probably not a real problem.
566: */
1.70 markus 567: /** hostaddr == 0! */
1.49 markus 568: switch (hostaddr->sa_family) {
569: case AF_INET:
1.108 markus 570: local = (ntohl(((struct sockaddr_in *)hostaddr)->
571: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 572: break;
573: case AF_INET6:
1.108 markus 574: local = IN6_IS_ADDR_LOOPBACK(
575: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 576: break;
577: default:
578: local = 0;
579: break;
580: }
1.111 markus 581: if (options.no_host_authentication_for_localhost == 1 && local &&
582: options.host_key_alias == NULL) {
1.88 markus 583: debug("Forcing accepting of host key for "
584: "loopback/localhost.");
1.108 markus 585: return 0;
1.49 markus 586: }
1.42 markus 587:
588: /*
1.88 markus 589: * We don't have the remote ip-address for connections
590: * using a proxy command
1.42 markus 591: */
1.84 markus 592: if (options.proxy_command == NULL) {
593: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 594: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 595: fatal("check_host_key: getnameinfo failed");
596: ip = xstrdup(ntop);
597: } else {
598: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 599: }
1.88 markus 600: /*
601: * Turn off check_host_ip if the connection is to localhost, via proxy
602: * command or if we don't have a hostname to compare with
603: */
604: if (options.check_host_ip &&
605: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
606: options.check_host_ip = 0;
1.86 markus 607:
608: /*
609: * Allow the user to record the key under a different name. This is
610: * useful for ssh tunneling over forwarded connections or if you run
611: * multiple sshd's on different ports on the same machine.
612: */
613: if (options.host_key_alias != NULL) {
614: host = options.host_key_alias;
615: debug("using hostkeyalias: %s", host);
1.84 markus 616: }
1.38 markus 617:
1.46 markus 618: /*
619: * Store the host key from the known host file in here so that we can
620: * compare it with the key for the IP address.
621: */
1.58 markus 622: file_key = key_new(host_key->type);
1.38 markus 623:
1.40 markus 624: /*
625: * Check if the host key is present in the user\'s list of known
626: * hosts or in the systemwide list.
627: */
1.85 markus 628: host_file = user_hostfile;
1.108 markus 629: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 630: file_key, &host_line);
1.85 markus 631: if (host_status == HOST_NEW) {
632: host_file = system_hostfile;
1.108 markus 633: host_status = check_host_in_hostfile(host_file, host, host_key,
634: file_key, &host_line);
1.85 markus 635: }
1.40 markus 636: /*
637: * Also perform check for the ip address, skip the check if we are
638: * localhost or the hostname was an ip address to begin with
639: */
1.88 markus 640: if (options.check_host_ip) {
1.58 markus 641: Key *ip_key = key_new(host_key->type);
1.38 markus 642:
1.85 markus 643: ip_file = user_hostfile;
1.108 markus 644: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
645: ip_key, &ip_line);
1.85 markus 646: if (ip_status == HOST_NEW) {
647: ip_file = system_hostfile;
1.108 markus 648: ip_status = check_host_in_hostfile(ip_file, ip,
649: host_key, ip_key, &ip_line);
1.85 markus 650: }
1.38 markus 651: if (host_status == HOST_CHANGED &&
1.58 markus 652: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 653: host_ip_differ = 1;
654:
1.58 markus 655: key_free(ip_key);
1.38 markus 656: } else
657: ip_status = host_status;
658:
1.58 markus 659: key_free(file_key);
1.38 markus 660:
661: switch (host_status) {
662: case HOST_OK:
663: /* The host is known and the key matches. */
1.72 markus 664: debug("Host '%.200s' is known and matches the %s host key.",
665: host, type);
1.85 markus 666: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 667: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 668: if (readonly)
1.138 itojun 669: logit("%s host key for IP address "
1.108 markus 670: "'%.128s' not in list of known hosts.",
671: type, ip);
672: else if (!add_host_to_hostfile(user_hostfile, ip,
1.160 ! djm 673: host_key, options.hash_known_hosts))
1.138 itojun 674: logit("Failed to add the %s host key for IP "
1.108 markus 675: "address '%.128s' to the list of known "
676: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 677: else
1.138 itojun 678: logit("Warning: Permanently added the %s host "
1.108 markus 679: "key for IP address '%.128s' to the list "
680: "of known hosts.", type, ip);
1.38 markus 681: }
682: break;
683: case HOST_NEW:
1.108 markus 684: if (readonly)
685: goto fail;
1.38 markus 686: /* The host is new. */
687: if (options.strict_host_key_checking == 1) {
1.108 markus 688: /*
689: * User has requested strict host key checking. We
690: * will not add the host key automatically. The only
691: * alternative left is to abort.
692: */
693: error("No %s host key is known for %.200s and you "
694: "have requested strict checking.", type, host);
695: goto fail;
1.38 markus 696: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 697: char msg1[1024], msg2[1024];
698:
699: if (show_other_keys(host, host_key))
700: snprintf(msg1, sizeof(msg1),
701: "\nbut keys of different type are already"
702: " known for this host.");
703: else
704: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 705: /* The default */
1.100 markus 706: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.145 jakob 707: msg2[0] = '\0';
708: if (options.verify_host_key_dns) {
1.153 jakob 709: if (matching_host_key_dns)
1.145 jakob 710: snprintf(msg2, sizeof(msg2),
711: "Matching host key fingerprint"
712: " found in DNS.\n");
713: else
714: snprintf(msg2, sizeof(msg2),
715: "No matching host key fingerprint"
716: " found in DNS.\n");
717: }
1.119 markus 718: snprintf(msg, sizeof(msg),
1.108 markus 719: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 720: "established%s\n"
1.145 jakob 721: "%s key fingerprint is %s.\n%s"
1.108 markus 722: "Are you sure you want to continue connecting "
1.132 markus 723: "(yes/no)? ",
1.145 jakob 724: host, ip, msg1, type, fp, msg2);
1.100 markus 725: xfree(fp);
1.119 markus 726: if (!confirm(msg))
1.108 markus 727: goto fail;
1.38 markus 728: }
1.88 markus 729: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 730: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
731: hostp = hostline;
732: } else
733: hostp = host;
734:
1.108 markus 735: /*
736: * If not in strict mode, add the key automatically to the
737: * local known_hosts file.
738: */
1.160 ! djm 739: if (!add_host_to_hostfile(user_hostfile, hostp, host_key,
! 740: options.hash_known_hosts))
1.138 itojun 741: logit("Failed to add the host to the list of known "
1.108 markus 742: "hosts (%.500s).", user_hostfile);
1.38 markus 743: else
1.138 itojun 744: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 745: "list of known hosts.", hostp, type);
1.38 markus 746: break;
747: case HOST_CHANGED:
748: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 749: char *key_msg;
1.38 markus 750: if (ip_status == HOST_NEW)
1.158 avsm 751: key_msg = "is unknown";
1.38 markus 752: else if (ip_status == HOST_OK)
1.158 avsm 753: key_msg = "is unchanged";
1.38 markus 754: else
1.158 avsm 755: key_msg = "has a different value";
1.38 markus 756: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
757: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
758: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 759: error("The %s host key for %s has changed,", type, host);
1.38 markus 760: error("and the key for the according IP address %s", ip);
1.158 avsm 761: error("%s. This could either mean that", key_msg);
1.38 markus 762: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 763: error("and its host key have changed at the same time.");
1.88 markus 764: if (ip_status != HOST_NEW)
1.85 markus 765: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 766: }
767: /* The host key has changed. */
1.150 jakob 768: warn_changed_key(host_key);
1.38 markus 769: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 770: user_hostfile);
1.85 markus 771: error("Offending key in %s:%d", host_file, host_line);
1.38 markus 772:
1.40 markus 773: /*
774: * If strict host key checking is in use, the user will have
775: * to edit the key manually and we can only abort.
776: */
1.108 markus 777: if (options.strict_host_key_checking) {
778: error("%s host key for %.200s has changed and you have "
779: "requested strict checking.", type, host);
780: goto fail;
781: }
1.38 markus 782:
1.40 markus 783: /*
784: * If strict host key checking has not been requested, allow
1.144 djm 785: * the connection but without MITM-able authentication or
1.40 markus 786: * agent forwarding.
787: */
1.38 markus 788: if (options.password_authentication) {
1.108 markus 789: error("Password authentication is disabled to avoid "
790: "man-in-the-middle attacks.");
1.38 markus 791: options.password_authentication = 0;
1.144 djm 792: }
793: if (options.kbd_interactive_authentication) {
794: error("Keyboard-interactive authentication is disabled"
795: " to avoid man-in-the-middle attacks.");
796: options.kbd_interactive_authentication = 0;
797: options.challenge_response_authentication = 0;
798: }
799: if (options.challenge_response_authentication) {
800: error("Challenge/response authentication is disabled"
801: " to avoid man-in-the-middle attacks.");
802: options.challenge_response_authentication = 0;
1.38 markus 803: }
804: if (options.forward_agent) {
1.108 markus 805: error("Agent forwarding is disabled to avoid "
806: "man-in-the-middle attacks.");
1.38 markus 807: options.forward_agent = 0;
1.83 markus 808: }
809: if (options.forward_x11) {
1.108 markus 810: error("X11 forwarding is disabled to avoid "
811: "man-in-the-middle attacks.");
1.83 markus 812: options.forward_x11 = 0;
813: }
1.108 markus 814: if (options.num_local_forwards > 0 ||
815: options.num_remote_forwards > 0) {
816: error("Port forwarding is disabled to avoid "
817: "man-in-the-middle attacks.");
818: options.num_local_forwards =
1.118 deraadt 819: options.num_remote_forwards = 0;
1.38 markus 820: }
1.40 markus 821: /*
822: * XXX Should permit the user to change to use the new id.
823: * This could be done by converting the host key to an
824: * identifying sentence, tell that the host identifies itself
825: * by that sentence, and ask the user if he/she whishes to
826: * accept the authentication.
827: */
1.38 markus 828: break;
1.132 markus 829: case HOST_FOUND:
830: fatal("internal error");
831: break;
1.88 markus 832: }
833:
834: if (options.check_host_ip && host_status != HOST_CHANGED &&
835: ip_status == HOST_CHANGED) {
1.119 markus 836: snprintf(msg, sizeof(msg),
837: "Warning: the %s host key for '%.200s' "
838: "differs from the key for the IP address '%.128s'"
839: "\nOffending key for IP in %s:%d",
840: type, host, ip, ip_file, ip_line);
841: if (host_status == HOST_OK) {
842: len = strlen(msg);
843: snprintf(msg + len, sizeof(msg) - len,
844: "\nMatching host key in %s:%d",
1.125 deraadt 845: host_file, host_line);
1.119 markus 846: }
1.88 markus 847: if (options.strict_host_key_checking == 1) {
1.143 djm 848: logit("%s", msg);
1.108 markus 849: error("Exiting, you have requested strict checking.");
850: goto fail;
1.88 markus 851: } else if (options.strict_host_key_checking == 2) {
1.119 markus 852: strlcat(msg, "\nAre you sure you want "
853: "to continue connecting (yes/no)? ", sizeof(msg));
854: if (!confirm(msg))
1.108 markus 855: goto fail;
1.119 markus 856: } else {
1.143 djm 857: logit("%s", msg);
1.88 markus 858: }
1.38 markus 859: }
1.82 provos 860:
861: xfree(ip);
1.108 markus 862: return 0;
863:
864: fail:
865: xfree(ip);
866: return -1;
867: }
868:
1.140 jakob 869: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 870: int
871: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
872: {
873: struct stat st;
1.153 jakob 874: int flags = 0;
1.140 jakob 875:
1.153 jakob 876: if (options.verify_host_key_dns &&
877: verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
878:
879: if (flags & DNS_VERIFY_FOUND) {
880:
881: if (options.verify_host_key_dns == 1 &&
882: flags & DNS_VERIFY_MATCH &&
883: flags & DNS_VERIFY_SECURE)
884: return 0;
885:
886: if (flags & DNS_VERIFY_MATCH) {
887: matching_host_key_dns = 1;
888: } else {
889: warn_changed_key(host_key);
890: error("Update the SSHFP RR in DNS with the new "
891: "host key to get rid of this message.");
892: }
1.140 jakob 893: }
894: }
1.108 markus 895:
896: /* return ok if the key can be found in an old keyfile */
897: if (stat(options.system_hostfile2, &st) == 0 ||
898: stat(options.user_hostfile2, &st) == 0) {
899: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
900: options.user_hostfile2, options.system_hostfile2) == 0)
901: return 0;
902: }
903: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
904: options.user_hostfile, options.system_hostfile);
1.51 markus 905: }
1.70 markus 906:
1.51 markus 907: /*
908: * Starts a dialog with the server, and authenticates the current user on the
909: * server. This does not need any extra privileges. The basic connection
910: * to the server must already have been established before this is called.
911: * If login fails, this function prints an error and never returns.
912: * This function does not require super-user privileges.
913: */
914: void
1.120 markus 915: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 916: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 917: {
918: char *host, *cp;
1.70 markus 919: char *server_user, *local_user;
920:
921: local_user = xstrdup(pw->pw_name);
922: server_user = options.user ? options.user : local_user;
1.51 markus 923:
924: /* Convert the user-supplied hostname into all lowercase. */
925: host = xstrdup(orighost);
926: for (cp = host; *cp; cp++)
927: if (isupper(*cp))
928: *cp = tolower(*cp);
929:
930: /* Exchange protocol version identification strings with the server. */
931: ssh_exchange_identification();
932:
933: /* Put the connection into non-blocking mode. */
934: packet_set_nonblocking();
935:
936: /* key exchange */
937: /* authenticate user */
1.59 markus 938: if (compat20) {
939: ssh_kex2(host, hostaddr);
1.120 markus 940: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 941: } else {
942: ssh_kex(host, hostaddr);
1.120 markus 943: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 944: }
1.97 markus 945: }
946:
947: void
948: ssh_put_password(char *password)
949: {
950: int size;
951: char *padded;
952:
1.99 deraadt 953: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 954: packet_put_cstring(password);
1.99 deraadt 955: return;
956: }
1.97 markus 957: size = roundup(strlen(password) + 1, 32);
958: padded = xmalloc(size);
959: memset(padded, 0, size);
960: strlcpy(padded, password, size);
961: packet_put_string(padded, size);
962: memset(padded, 0, size);
963: xfree(padded);
1.132 markus 964: }
965:
966: static int
967: show_key_from_file(const char *file, const char *host, int keytype)
968: {
969: Key *found;
970: char *fp;
971: int line, ret;
972:
973: found = key_new(keytype);
974: if ((ret = lookup_key_in_hostfile_by_type(file, host,
975: keytype, found, &line))) {
976: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 977: logit("WARNING: %s key found for host %s\n"
1.133 markus 978: "in %s:%d\n"
1.132 markus 979: "%s key fingerprint %s.",
980: key_type(found), host, file, line,
981: key_type(found), fp);
982: xfree(fp);
983: }
984: key_free(found);
985: return (ret);
986: }
987:
988: /* print all known host keys for a given host, but skip keys of given type */
989: static int
990: show_other_keys(const char *host, Key *key)
991: {
992: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
993: int i, found = 0;
994:
995: for (i = 0; type[i] != -1; i++) {
996: if (type[i] == key->type)
997: continue;
998: if (type[i] != KEY_RSA1 &&
999: show_key_from_file(options.user_hostfile2, host, type[i])) {
1000: found = 1;
1001: continue;
1002: }
1003: if (type[i] != KEY_RSA1 &&
1004: show_key_from_file(options.system_hostfile2, host, type[i])) {
1005: found = 1;
1006: continue;
1007: }
1008: if (show_key_from_file(options.user_hostfile, host, type[i])) {
1009: found = 1;
1010: continue;
1011: }
1012: if (show_key_from_file(options.system_hostfile, host, type[i])) {
1013: found = 1;
1014: continue;
1015: }
1016: debug2("no key of type %d for host %s", type[i], host);
1017: }
1018: return (found);
1.150 jakob 1019: }
1020:
1021: static void
1022: warn_changed_key(Key *host_key)
1023: {
1024: char *fp;
1.151 jakob 1025: const char *type = key_type(host_key);
1.150 jakob 1026:
1027: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1028:
1029: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1030: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1031: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1032: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1033: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1034: error("It is also possible that the %s host key has just been changed.", type);
1035: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1036: type, fp);
1037: error("Please contact your system administrator.");
1038:
1039: xfree(fp);
1.1 deraadt 1040: }
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