Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.140
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"
1.140 ! jakob 16: RCSID("$OpenBSD: sshconnect.c,v 1.139 2003/04/14 14:17:50 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: #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:
1.39 deraadt 217: /*
1.49 markus 218: * Opens a TCP/IP connection to the remote server on the given host.
219: * The address of the remote host will be returned in hostaddr.
1.124 markus 220: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 221: * a privileged port will be allocated to make the connection.
1.124 markus 222: * This requires super-user privileges if needpriv is true.
1.39 deraadt 223: * Connection_attempts specifies the maximum number of tries (one per
224: * second). If proxy_command is non-NULL, it specifies the command (with %h
225: * and %p substituted for host and port, respectively) to use to contact
226: * the daemon.
1.110 markus 227: * Return values:
228: * 0 for OK
229: * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
230: * ECONNABORTED if we failed without a "Connection refused"
231: * Suitable error messages for the connection failure will already have been
232: * printed.
1.39 deraadt 233: */
1.38 markus 234: int
1.49 markus 235: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 236: u_short port, int family, int connection_attempts,
1.124 markus 237: int needpriv, const char *proxy_command)
1.1 deraadt 238: {
1.90 markus 239: int gaierr;
240: int on = 1;
1.49 markus 241: int sock = -1, attempt;
1.90 markus 242: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 243: struct addrinfo hints, *ai, *aitop;
1.90 markus 244: struct servent *sp;
1.110 markus 245: /*
246: * Did we get only other errors than "Connection refused" (which
247: * should block fallback to rsh and similar), or did we get at least
248: * one "Connection refused"?
249: */
250: int full_failure = 1;
1.38 markus 251:
1.136 markus 252: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 253:
254: /* Get default port if port has not been set. */
255: if (port == 0) {
256: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
257: if (sp)
258: port = ntohs(sp->s_port);
259: else
260: port = SSH_DEFAULT_PORT;
261: }
262: /* If a proxy command is given, connect using it. */
263: if (proxy_command != NULL)
1.124 markus 264: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 265:
266: /* No proxy command. */
267:
1.49 markus 268: memset(&hints, 0, sizeof(hints));
1.115 markus 269: hints.ai_family = family;
1.49 markus 270: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 271: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 272: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 273: fatal("%s: %.100s: %s", __progname, host,
274: gai_strerror(gaierr));
1.38 markus 275:
1.46 markus 276: /*
277: * Try to connect several times. On some machines, the first time
278: * will sometimes fail. In general socket code appears to behave
279: * quite magically on many machines.
1.110 markus 280: */
281: for (attempt = 0; ;) {
1.38 markus 282: if (attempt > 0)
283: debug("Trying again...");
284:
1.49 markus 285: /* Loop through addresses for this host, and try each one in
1.68 markus 286: sequence until the connection succeeds. */
1.49 markus 287: for (ai = aitop; ai; ai = ai->ai_next) {
288: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
289: continue;
290: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
291: ntop, sizeof(ntop), strport, sizeof(strport),
292: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
293: error("ssh_connect: getnameinfo failed");
294: continue;
295: }
296: debug("Connecting to %.200s [%.100s] port %s.",
297: host, ntop, strport);
298:
299: /* Create a socket for connecting. */
1.139 markus 300: sock = ssh_create_socket(needpriv, ai);
1.49 markus 301: if (sock < 0)
1.110 markus 302: /* Any error is already output */
1.49 markus 303: continue;
304:
305: if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
306: /* Successful connection. */
1.102 markus 307: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 308: break;
1.49 markus 309: } else {
1.110 markus 310: if (errno == ECONNREFUSED)
311: full_failure = 0;
1.131 itojun 312: debug("connect to address %s port %s: %s",
313: ntop, strport, strerror(errno));
1.40 markus 314: /*
315: * Close the failed socket; there appear to
316: * be some problems when reusing a socket for
317: * which connect() has already returned an
318: * error.
319: */
1.38 markus 320: close(sock);
321: }
322: }
1.49 markus 323: if (ai)
324: break; /* Successful connection. */
1.1 deraadt 325:
1.110 markus 326: attempt++;
327: if (attempt >= connection_attempts)
328: break;
1.38 markus 329: /* Sleep a moment before retrying. */
330: sleep(1);
331: }
1.49 markus 332:
333: freeaddrinfo(aitop);
334:
1.38 markus 335: /* Return failure if we didn't get a successful connection. */
1.130 itojun 336: if (attempt >= connection_attempts) {
1.138 itojun 337: logit("ssh: connect to host %s port %s: %s",
1.130 itojun 338: host, strport, strerror(errno));
1.110 markus 339: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.130 itojun 340: }
1.38 markus 341:
342: debug("Connection established.");
1.90 markus 343:
344: /* Set keepalives if requested. */
345: if (options.keepalives &&
346: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
347: sizeof(on)) < 0)
348: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 349:
350: /* Set the connection. */
351: packet_set_connection(sock, sock);
1.1 deraadt 352:
1.110 markus 353: return 0;
1.59 markus 354: }
355:
1.43 markus 356: /*
1.39 deraadt 357: * Waits for the server identification string, and sends our own
358: * identification string.
359: */
1.109 itojun 360: static void
1.95 itojun 361: ssh_exchange_identification(void)
1.1 deraadt 362: {
1.38 markus 363: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 364: int remote_major, remote_minor, i, mismatch;
1.38 markus 365: int connection_in = packet_get_connection_in();
366: int connection_out = packet_get_connection_out();
1.93 stevesk 367: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 368:
369: /* Read other side\'s version identification. */
1.75 markus 370: for (;;) {
371: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 372: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 373: if (len < 0)
374: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
375: if (len != 1)
376: fatal("ssh_exchange_identification: Connection closed by remote host");
377: if (buf[i] == '\r') {
378: buf[i] = '\n';
379: buf[i + 1] = 0;
380: continue; /**XXX wait for \n */
381: }
382: if (buf[i] == '\n') {
383: buf[i + 1] = 0;
384: break;
385: }
1.38 markus 386: }
1.75 markus 387: buf[sizeof(buf) - 1] = 0;
1.76 markus 388: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 389: break;
1.75 markus 390: debug("ssh_exchange_identification: %s", buf);
1.38 markus 391: }
1.59 markus 392: server_version_string = xstrdup(buf);
1.38 markus 393:
1.40 markus 394: /*
395: * Check that the versions match. In future this might accept
396: * several versions and set appropriate flags to handle them.
397: */
1.59 markus 398: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
399: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 400: fatal("Bad remote protocol version identification: '%.100s'", buf);
401: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 402: remote_major, remote_minor, remote_version);
1.38 markus 403:
1.59 markus 404: compat_datafellows(remote_version);
1.64 markus 405: mismatch = 0;
1.59 markus 406:
1.116 deraadt 407: switch (remote_major) {
1.64 markus 408: case 1:
409: if (remote_minor == 99 &&
410: (options.protocol & SSH_PROTO_2) &&
411: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
412: enable_compat20();
413: break;
414: }
415: if (!(options.protocol & SSH_PROTO_1)) {
416: mismatch = 1;
417: break;
418: }
419: if (remote_minor < 3) {
420: fatal("Remote machine has too old SSH software version.");
1.81 markus 421: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 422: /* We speak 1.3, too. */
423: enable_compat13();
1.81 markus 424: minor1 = 3;
1.64 markus 425: if (options.forward_agent) {
1.138 itojun 426: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 427: options.forward_agent = 0;
428: }
429: }
430: break;
431: case 2:
432: if (options.protocol & SSH_PROTO_2) {
433: enable_compat20();
434: break;
1.38 markus 435: }
1.64 markus 436: /* FALLTHROUGH */
1.68 markus 437: default:
1.64 markus 438: mismatch = 1;
439: break;
1.38 markus 440: }
1.64 markus 441: if (mismatch)
1.38 markus 442: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 443: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
444: remote_major);
1.38 markus 445: /* Send our own protocol version identification. */
446: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 447: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 448: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 449: SSH_VERSION);
1.45 deraadt 450: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 451: fatal("write: %.100s", strerror(errno));
1.59 markus 452: client_version_string = xstrdup(buf);
453: chop(client_version_string);
454: chop(server_version_string);
455: debug("Local version string %.100s", client_version_string);
1.1 deraadt 456: }
457:
1.96 markus 458: /* defaults to 'no' */
1.109 itojun 459: static int
1.112 markus 460: confirm(const char *prompt)
1.1 deraadt 461: {
1.119 markus 462: const char *msg, *again = "Please type 'yes' or 'no': ";
463: char *p;
464: int ret = -1;
1.96 markus 465:
466: if (options.batch_mode)
467: return 0;
1.119 markus 468: for (msg = prompt;;msg = again) {
469: p = read_passphrase(msg, RP_ECHO);
470: if (p == NULL ||
471: (p[0] == '\0') || (p[0] == '\n') ||
472: strncasecmp(p, "no", 2) == 0)
473: ret = 0;
1.127 markus 474: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 475: ret = 1;
476: if (p)
477: xfree(p);
478: if (ret != -1)
479: return ret;
1.1 deraadt 480: }
481: }
482:
1.39 deraadt 483: /*
1.108 markus 484: * check whether the supplied host key is valid, return -1 if the key
485: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 486: */
1.109 itojun 487: static int
1.70 markus 488: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 489: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 490: {
1.58 markus 491: Key *file_key;
1.72 markus 492: char *type = key_type(host_key);
1.46 markus 493: char *ip = NULL;
1.100 markus 494: char hostline[1000], *hostp, *fp;
1.38 markus 495: HostStatus host_status;
496: HostStatus ip_status;
1.49 markus 497: int local = 0, host_ip_differ = 0;
498: char ntop[NI_MAXHOST];
1.119 markus 499: char msg[1024];
1.132 markus 500: int len, host_line, ip_line, has_keys;
1.85 markus 501: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 502:
503: /*
504: * Force accepting of the host key for loopback/localhost. The
505: * problem is that if the home directory is NFS-mounted to multiple
506: * machines, localhost will refer to a different machine in each of
507: * them, and the user will get bogus HOST_CHANGED warnings. This
508: * essentially disables host authentication for localhost; however,
509: * this is probably not a real problem.
510: */
1.70 markus 511: /** hostaddr == 0! */
1.49 markus 512: switch (hostaddr->sa_family) {
513: case AF_INET:
1.108 markus 514: local = (ntohl(((struct sockaddr_in *)hostaddr)->
515: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 516: break;
517: case AF_INET6:
1.108 markus 518: local = IN6_IS_ADDR_LOOPBACK(
519: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 520: break;
521: default:
522: local = 0;
523: break;
524: }
1.111 markus 525: if (options.no_host_authentication_for_localhost == 1 && local &&
526: options.host_key_alias == NULL) {
1.88 markus 527: debug("Forcing accepting of host key for "
528: "loopback/localhost.");
1.108 markus 529: return 0;
1.49 markus 530: }
1.42 markus 531:
532: /*
1.88 markus 533: * We don't have the remote ip-address for connections
534: * using a proxy command
1.42 markus 535: */
1.84 markus 536: if (options.proxy_command == NULL) {
537: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 538: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 539: fatal("check_host_key: getnameinfo failed");
540: ip = xstrdup(ntop);
541: } else {
542: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 543: }
1.88 markus 544: /*
545: * Turn off check_host_ip if the connection is to localhost, via proxy
546: * command or if we don't have a hostname to compare with
547: */
548: if (options.check_host_ip &&
549: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
550: options.check_host_ip = 0;
1.86 markus 551:
552: /*
553: * Allow the user to record the key under a different name. This is
554: * useful for ssh tunneling over forwarded connections or if you run
555: * multiple sshd's on different ports on the same machine.
556: */
557: if (options.host_key_alias != NULL) {
558: host = options.host_key_alias;
559: debug("using hostkeyalias: %s", host);
1.84 markus 560: }
1.38 markus 561:
1.46 markus 562: /*
563: * Store the host key from the known host file in here so that we can
564: * compare it with the key for the IP address.
565: */
1.58 markus 566: file_key = key_new(host_key->type);
1.38 markus 567:
1.40 markus 568: /*
569: * Check if the host key is present in the user\'s list of known
570: * hosts or in the systemwide list.
571: */
1.85 markus 572: host_file = user_hostfile;
1.108 markus 573: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 574: file_key, &host_line);
1.85 markus 575: if (host_status == HOST_NEW) {
576: host_file = system_hostfile;
1.108 markus 577: host_status = check_host_in_hostfile(host_file, host, host_key,
578: file_key, &host_line);
1.85 markus 579: }
1.40 markus 580: /*
581: * Also perform check for the ip address, skip the check if we are
582: * localhost or the hostname was an ip address to begin with
583: */
1.88 markus 584: if (options.check_host_ip) {
1.58 markus 585: Key *ip_key = key_new(host_key->type);
1.38 markus 586:
1.85 markus 587: ip_file = user_hostfile;
1.108 markus 588: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
589: ip_key, &ip_line);
1.85 markus 590: if (ip_status == HOST_NEW) {
591: ip_file = system_hostfile;
1.108 markus 592: ip_status = check_host_in_hostfile(ip_file, ip,
593: host_key, ip_key, &ip_line);
1.85 markus 594: }
1.38 markus 595: if (host_status == HOST_CHANGED &&
1.58 markus 596: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 597: host_ip_differ = 1;
598:
1.58 markus 599: key_free(ip_key);
1.38 markus 600: } else
601: ip_status = host_status;
602:
1.58 markus 603: key_free(file_key);
1.38 markus 604:
605: switch (host_status) {
606: case HOST_OK:
607: /* The host is known and the key matches. */
1.72 markus 608: debug("Host '%.200s' is known and matches the %s host key.",
609: host, type);
1.85 markus 610: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 611: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 612: if (readonly)
1.138 itojun 613: logit("%s host key for IP address "
1.108 markus 614: "'%.128s' not in list of known hosts.",
615: type, ip);
616: else if (!add_host_to_hostfile(user_hostfile, ip,
1.118 deraadt 617: host_key))
1.138 itojun 618: logit("Failed to add the %s host key for IP "
1.108 markus 619: "address '%.128s' to the list of known "
620: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 621: else
1.138 itojun 622: logit("Warning: Permanently added the %s host "
1.108 markus 623: "key for IP address '%.128s' to the list "
624: "of known hosts.", type, ip);
1.38 markus 625: }
626: break;
627: case HOST_NEW:
1.108 markus 628: if (readonly)
629: goto fail;
1.38 markus 630: /* The host is new. */
631: if (options.strict_host_key_checking == 1) {
1.108 markus 632: /*
633: * User has requested strict host key checking. We
634: * will not add the host key automatically. The only
635: * alternative left is to abort.
636: */
637: error("No %s host key is known for %.200s and you "
638: "have requested strict checking.", type, host);
639: goto fail;
1.38 markus 640: } else if (options.strict_host_key_checking == 2) {
1.132 markus 641: has_keys = show_other_keys(host, host_key);
1.38 markus 642: /* The default */
1.100 markus 643: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.119 markus 644: snprintf(msg, sizeof(msg),
1.108 markus 645: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 646: "established%s\n"
1.72 markus 647: "%s key fingerprint is %s.\n"
1.108 markus 648: "Are you sure you want to continue connecting "
1.132 markus 649: "(yes/no)? ",
1.137 deraadt 650: host, ip,
651: has_keys ? ",\nbut keys of different type are already "
652: "known for this host." : ".",
653: type, fp);
1.100 markus 654: xfree(fp);
1.119 markus 655: if (!confirm(msg))
1.108 markus 656: goto fail;
1.38 markus 657: }
1.88 markus 658: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 659: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
660: hostp = hostline;
661: } else
662: hostp = host;
663:
1.108 markus 664: /*
665: * If not in strict mode, add the key automatically to the
666: * local known_hosts file.
667: */
1.70 markus 668: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.138 itojun 669: logit("Failed to add the host to the list of known "
1.108 markus 670: "hosts (%.500s).", user_hostfile);
1.38 markus 671: else
1.138 itojun 672: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 673: "list of known hosts.", hostp, type);
1.38 markus 674: break;
675: case HOST_CHANGED:
676: if (options.check_host_ip && host_ip_differ) {
677: char *msg;
678: if (ip_status == HOST_NEW)
679: msg = "is unknown";
680: else if (ip_status == HOST_OK)
681: msg = "is unchanged";
682: else
683: msg = "has a different value";
684: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
685: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
686: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 687: error("The %s host key for %s has changed,", type, host);
1.38 markus 688: error("and the key for the according IP address %s", ip);
689: error("%s. This could either mean that", msg);
690: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 691: error("and its host key have changed at the same time.");
1.88 markus 692: if (ip_status != HOST_NEW)
1.85 markus 693: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 694: }
695: /* The host key has changed. */
1.100 markus 696: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 697: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 698: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 699: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
700: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
701: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 702: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 703: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.100 markus 704: type, fp);
1.38 markus 705: error("Please contact your system administrator.");
706: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 707: user_hostfile);
1.85 markus 708: error("Offending key in %s:%d", host_file, host_line);
1.100 markus 709: xfree(fp);
1.38 markus 710:
1.40 markus 711: /*
712: * If strict host key checking is in use, the user will have
713: * to edit the key manually and we can only abort.
714: */
1.108 markus 715: if (options.strict_host_key_checking) {
716: error("%s host key for %.200s has changed and you have "
717: "requested strict checking.", type, host);
718: goto fail;
719: }
1.38 markus 720:
1.40 markus 721: /*
722: * If strict host key checking has not been requested, allow
723: * the connection but without password authentication or
724: * agent forwarding.
725: */
1.38 markus 726: if (options.password_authentication) {
1.108 markus 727: error("Password authentication is disabled to avoid "
728: "man-in-the-middle attacks.");
1.38 markus 729: options.password_authentication = 0;
730: }
731: if (options.forward_agent) {
1.108 markus 732: error("Agent forwarding is disabled to avoid "
733: "man-in-the-middle attacks.");
1.38 markus 734: options.forward_agent = 0;
1.83 markus 735: }
736: if (options.forward_x11) {
1.108 markus 737: error("X11 forwarding is disabled to avoid "
738: "man-in-the-middle attacks.");
1.83 markus 739: options.forward_x11 = 0;
740: }
1.108 markus 741: if (options.num_local_forwards > 0 ||
742: options.num_remote_forwards > 0) {
743: error("Port forwarding is disabled to avoid "
744: "man-in-the-middle attacks.");
745: options.num_local_forwards =
1.118 deraadt 746: options.num_remote_forwards = 0;
1.38 markus 747: }
1.40 markus 748: /*
749: * XXX Should permit the user to change to use the new id.
750: * This could be done by converting the host key to an
751: * identifying sentence, tell that the host identifies itself
752: * by that sentence, and ask the user if he/she whishes to
753: * accept the authentication.
754: */
1.38 markus 755: break;
1.132 markus 756: case HOST_FOUND:
757: fatal("internal error");
758: break;
1.88 markus 759: }
760:
761: if (options.check_host_ip && host_status != HOST_CHANGED &&
762: ip_status == HOST_CHANGED) {
1.119 markus 763: snprintf(msg, sizeof(msg),
764: "Warning: the %s host key for '%.200s' "
765: "differs from the key for the IP address '%.128s'"
766: "\nOffending key for IP in %s:%d",
767: type, host, ip, ip_file, ip_line);
768: if (host_status == HOST_OK) {
769: len = strlen(msg);
770: snprintf(msg + len, sizeof(msg) - len,
771: "\nMatching host key in %s:%d",
1.125 deraadt 772: host_file, host_line);
1.119 markus 773: }
1.88 markus 774: if (options.strict_host_key_checking == 1) {
1.138 itojun 775: logit(msg);
1.108 markus 776: error("Exiting, you have requested strict checking.");
777: goto fail;
1.88 markus 778: } else if (options.strict_host_key_checking == 2) {
1.119 markus 779: strlcat(msg, "\nAre you sure you want "
780: "to continue connecting (yes/no)? ", sizeof(msg));
781: if (!confirm(msg))
1.108 markus 782: goto fail;
1.119 markus 783: } else {
1.138 itojun 784: logit(msg);
1.88 markus 785: }
1.38 markus 786: }
1.82 provos 787:
788: xfree(ip);
1.108 markus 789: return 0;
790:
791: fail:
792: xfree(ip);
793: return -1;
794: }
795:
1.140 ! jakob 796: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 797: int
798: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
799: {
800: struct stat st;
1.140 ! jakob 801:
! 802: #ifdef DNS
! 803: if (options.verify_host_key_dns) {
! 804: switch(verify_host_key_dns(host, hostaddr, host_key)) {
! 805: case DNS_VERIFY_OK:
! 806: return 0;
! 807: case DNS_VERIFY_FAILED:
! 808: return -1;
! 809: case DNS_VERIFY_ERROR:
! 810: break;
! 811: default:
! 812: debug3("bad return value from verify_host_key_dns");
! 813: break;
! 814: }
! 815: }
! 816: #endif /* DNS */
1.108 markus 817:
818: /* return ok if the key can be found in an old keyfile */
819: if (stat(options.system_hostfile2, &st) == 0 ||
820: stat(options.user_hostfile2, &st) == 0) {
821: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
822: options.user_hostfile2, options.system_hostfile2) == 0)
823: return 0;
824: }
825: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
826: options.user_hostfile, options.system_hostfile);
1.51 markus 827: }
1.70 markus 828:
1.51 markus 829: /*
830: * Starts a dialog with the server, and authenticates the current user on the
831: * server. This does not need any extra privileges. The basic connection
832: * to the server must already have been established before this is called.
833: * If login fails, this function prints an error and never returns.
834: * This function does not require super-user privileges.
835: */
836: void
1.120 markus 837: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 838: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 839: {
840: char *host, *cp;
1.70 markus 841: char *server_user, *local_user;
842:
843: local_user = xstrdup(pw->pw_name);
844: server_user = options.user ? options.user : local_user;
1.51 markus 845:
846: /* Convert the user-supplied hostname into all lowercase. */
847: host = xstrdup(orighost);
848: for (cp = host; *cp; cp++)
849: if (isupper(*cp))
850: *cp = tolower(*cp);
851:
852: /* Exchange protocol version identification strings with the server. */
853: ssh_exchange_identification();
854:
855: /* Put the connection into non-blocking mode. */
856: packet_set_nonblocking();
857:
858: /* key exchange */
859: /* authenticate user */
1.59 markus 860: if (compat20) {
861: ssh_kex2(host, hostaddr);
1.120 markus 862: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 863: } else {
864: ssh_kex(host, hostaddr);
1.120 markus 865: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 866: }
1.97 markus 867: }
868:
869: void
870: ssh_put_password(char *password)
871: {
872: int size;
873: char *padded;
874:
1.99 deraadt 875: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 876: packet_put_cstring(password);
1.99 deraadt 877: return;
878: }
1.97 markus 879: size = roundup(strlen(password) + 1, 32);
880: padded = xmalloc(size);
881: memset(padded, 0, size);
882: strlcpy(padded, password, size);
883: packet_put_string(padded, size);
884: memset(padded, 0, size);
885: xfree(padded);
1.132 markus 886: }
887:
888: static int
889: show_key_from_file(const char *file, const char *host, int keytype)
890: {
891: Key *found;
892: char *fp;
893: int line, ret;
894:
895: found = key_new(keytype);
896: if ((ret = lookup_key_in_hostfile_by_type(file, host,
897: keytype, found, &line))) {
898: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 899: logit("WARNING: %s key found for host %s\n"
1.133 markus 900: "in %s:%d\n"
1.132 markus 901: "%s key fingerprint %s.",
902: key_type(found), host, file, line,
903: key_type(found), fp);
904: xfree(fp);
905: }
906: key_free(found);
907: return (ret);
908: }
909:
910: /* print all known host keys for a given host, but skip keys of given type */
911: static int
912: show_other_keys(const char *host, Key *key)
913: {
914: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
915: int i, found = 0;
916:
917: for (i = 0; type[i] != -1; i++) {
918: if (type[i] == key->type)
919: continue;
920: if (type[i] != KEY_RSA1 &&
921: show_key_from_file(options.user_hostfile2, host, type[i])) {
922: found = 1;
923: continue;
924: }
925: if (type[i] != KEY_RSA1 &&
926: show_key_from_file(options.system_hostfile2, host, type[i])) {
927: found = 1;
928: continue;
929: }
930: if (show_key_from_file(options.user_hostfile, host, type[i])) {
931: found = 1;
932: continue;
933: }
934: if (show_key_from_file(options.system_hostfile, host, type[i])) {
935: found = 1;
936: continue;
937: }
938: debug2("no key of type %d for host %s", type[i], host);
939: }
940: return (found);
1.1 deraadt 941: }
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