Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.129
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"
1.129 ! itojun 16: RCSID("$OpenBSD: sshconnect.c,v 1.128 2002/07/09 11:56:50 itojun 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:
1.70 markus 36: char *client_version_string = NULL;
37: char *server_version_string = NULL;
1.59 markus 38:
1.124 markus 39: /* import */
1.43 markus 40: extern Options options;
1.50 markus 41: extern char *__progname;
1.124 markus 42: extern uid_t original_real_uid;
43: extern uid_t original_effective_uid;
1.91 markus 44:
1.129 ! itojun 45: #if 0
1.110 markus 46: static const char *
1.123 itojun 47: sockaddr_ntop(struct sockaddr *sa, socklen_t salen)
1.110 markus 48: {
1.121 itojun 49: static char addrbuf[NI_MAXHOST];
1.110 markus 50:
1.123 itojun 51: if (getnameinfo(sa, salen, addrbuf, sizeof(addrbuf), NULL, 0,
1.121 itojun 52: NI_NUMERICHOST) != 0)
1.122 markus 53: fatal("sockaddr_ntop: getnameinfo NI_NUMERICHOST failed");
1.110 markus 54: return addrbuf;
55: }
1.129 ! itojun 56: #endif
1.110 markus 57:
1.39 deraadt 58: /*
59: * Connect to the given ssh server using a proxy command.
60: */
1.109 itojun 61: static int
1.124 markus 62: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 63: {
1.38 markus 64: Buffer command;
65: const char *cp;
66: char *command_string;
67: int pin[2], pout[2];
1.69 deraadt 68: pid_t pid;
1.49 markus 69: char strport[NI_MAXSERV];
1.38 markus 70:
71: /* Convert the port number into a string. */
1.49 markus 72: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 73:
74: /* Build the final command string in the buffer by making the
75: appropriate substitutions to the given proxy command. */
76: buffer_init(&command);
77: for (cp = proxy_command; *cp; cp++) {
78: if (cp[0] == '%' && cp[1] == '%') {
79: buffer_append(&command, "%", 1);
80: cp++;
81: continue;
82: }
83: if (cp[0] == '%' && cp[1] == 'h') {
84: buffer_append(&command, host, strlen(host));
85: cp++;
86: continue;
87: }
88: if (cp[0] == '%' && cp[1] == 'p') {
1.49 markus 89: buffer_append(&command, strport, strlen(strport));
1.38 markus 90: cp++;
91: continue;
92: }
93: buffer_append(&command, cp, 1);
94: }
95: buffer_append(&command, "\0", 1);
96:
97: /* Get the final command string. */
98: command_string = buffer_ptr(&command);
99:
100: /* Create pipes for communicating with the proxy. */
101: if (pipe(pin) < 0 || pipe(pout) < 0)
102: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 103: strerror(errno));
1.38 markus 104:
105: debug("Executing proxy command: %.500s", command_string);
106:
107: /* Fork and execute the proxy command. */
108: if ((pid = fork()) == 0) {
109: char *argv[10];
110:
111: /* Child. Permanently give up superuser privileges. */
1.124 markus 112: seteuid(original_real_uid);
113: setuid(original_real_uid);
1.38 markus 114:
115: /* Redirect stdin and stdout. */
116: close(pin[1]);
117: if (pin[0] != 0) {
118: if (dup2(pin[0], 0) < 0)
119: perror("dup2 stdin");
120: close(pin[0]);
121: }
122: close(pout[0]);
123: if (dup2(pout[1], 1) < 0)
124: perror("dup2 stdout");
125: /* Cannot be 1 because pin allocated two descriptors. */
126: close(pout[1]);
127:
128: /* Stderr is left as it is so that error messages get
129: printed on the user's terminal. */
1.89 markus 130: argv[0] = _PATH_BSHELL;
1.38 markus 131: argv[1] = "-c";
132: argv[2] = command_string;
133: argv[3] = NULL;
134:
135: /* Execute the proxy command. Note that we gave up any
136: extra privileges above. */
1.89 markus 137: execv(argv[0], argv);
138: perror(argv[0]);
1.38 markus 139: exit(1);
140: }
141: /* Parent. */
142: if (pid < 0)
143: fatal("fork failed: %.100s", strerror(errno));
144:
145: /* Close child side of the descriptors. */
146: close(pin[0]);
147: close(pout[1]);
148:
149: /* Free the command name. */
150: buffer_free(&command);
151:
152: /* Set the connection file descriptors. */
153: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 154:
1.110 markus 155: /* Indicate OK return */
156: return 0;
1.1 deraadt 157: }
158:
1.39 deraadt 159: /*
160: * Creates a (possibly privileged) socket for use as the ssh connection.
161: */
1.109 itojun 162: static int
1.124 markus 163: ssh_create_socket(int privileged, int family)
1.1 deraadt 164: {
1.105 markus 165: int sock, gaierr;
166: struct addrinfo hints, *res;
1.1 deraadt 167:
1.40 markus 168: /*
169: * If we are running as root and want to connect to a privileged
170: * port, bind our own socket to a privileged port.
171: */
1.38 markus 172: if (privileged) {
173: int p = IPPORT_RESERVED - 1;
1.124 markus 174: PRIV_START;
1.49 markus 175: sock = rresvport_af(&p, family);
1.124 markus 176: PRIV_END;
1.38 markus 177: if (sock < 0)
1.55 markus 178: error("rresvport: af=%d %.100s", family, strerror(errno));
179: else
180: debug("Allocated local port %d.", p);
1.105 markus 181: return sock;
182: }
183: sock = socket(family, SOCK_STREAM, 0);
184: if (sock < 0)
185: error("socket: %.100s", strerror(errno));
186:
187: /* Bind the socket to an alternative local IP address */
188: if (options.bind_address == NULL)
189: return sock;
190:
191: memset(&hints, 0, sizeof(hints));
1.114 markus 192: hints.ai_family = family;
1.105 markus 193: hints.ai_socktype = SOCK_STREAM;
194: hints.ai_flags = AI_PASSIVE;
195: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
196: if (gaierr) {
197: error("getaddrinfo: %s: %s", options.bind_address,
198: gai_strerror(gaierr));
199: close(sock);
200: return -1;
201: }
202: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
203: error("bind: %s: %s", options.bind_address, strerror(errno));
204: close(sock);
205: freeaddrinfo(res);
206: return -1;
1.38 markus 207: }
1.105 markus 208: freeaddrinfo(res);
1.38 markus 209: return sock;
1.1 deraadt 210: }
211:
1.39 deraadt 212: /*
1.49 markus 213: * Opens a TCP/IP connection to the remote server on the given host.
214: * The address of the remote host will be returned in hostaddr.
1.124 markus 215: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 216: * a privileged port will be allocated to make the connection.
1.124 markus 217: * This requires super-user privileges if needpriv is true.
1.39 deraadt 218: * Connection_attempts specifies the maximum number of tries (one per
219: * second). If proxy_command is non-NULL, it specifies the command (with %h
220: * and %p substituted for host and port, respectively) to use to contact
221: * the daemon.
1.110 markus 222: * Return values:
223: * 0 for OK
224: * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
225: * ECONNABORTED if we failed without a "Connection refused"
226: * Suitable error messages for the connection failure will already have been
227: * printed.
1.39 deraadt 228: */
1.38 markus 229: int
1.49 markus 230: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 231: u_short port, int family, int connection_attempts,
1.124 markus 232: int needpriv, const char *proxy_command)
1.1 deraadt 233: {
1.90 markus 234: int gaierr;
235: int on = 1;
1.49 markus 236: int sock = -1, attempt;
1.90 markus 237: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 238: struct addrinfo hints, *ai, *aitop;
1.38 markus 239: struct linger linger;
1.90 markus 240: struct servent *sp;
1.110 markus 241: /*
242: * Did we get only other errors than "Connection refused" (which
243: * should block fallback to rsh and similar), or did we get at least
244: * one "Connection refused"?
245: */
246: int full_failure = 1;
1.38 markus 247:
1.124 markus 248: debug("ssh_connect: needpriv %d", needpriv);
1.38 markus 249:
250: /* Get default port if port has not been set. */
251: if (port == 0) {
252: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
253: if (sp)
254: port = ntohs(sp->s_port);
255: else
256: port = SSH_DEFAULT_PORT;
257: }
258: /* If a proxy command is given, connect using it. */
259: if (proxy_command != NULL)
1.124 markus 260: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 261:
262: /* No proxy command. */
263:
1.49 markus 264: memset(&hints, 0, sizeof(hints));
1.115 markus 265: hints.ai_family = family;
1.49 markus 266: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 267: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 268: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 269: fatal("%s: %.100s: %s", __progname, host,
270: gai_strerror(gaierr));
1.38 markus 271:
1.46 markus 272: /*
273: * Try to connect several times. On some machines, the first time
274: * will sometimes fail. In general socket code appears to behave
275: * quite magically on many machines.
1.110 markus 276: */
277: for (attempt = 0; ;) {
1.38 markus 278: if (attempt > 0)
279: debug("Trying again...");
280:
1.49 markus 281: /* Loop through addresses for this host, and try each one in
1.68 markus 282: sequence until the connection succeeds. */
1.49 markus 283: for (ai = aitop; ai; ai = ai->ai_next) {
284: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
285: continue;
286: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
287: ntop, sizeof(ntop), strport, sizeof(strport),
288: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
289: error("ssh_connect: getnameinfo failed");
290: continue;
291: }
292: debug("Connecting to %.200s [%.100s] port %s.",
293: host, ntop, strport);
294:
295: /* Create a socket for connecting. */
1.124 markus 296: sock = ssh_create_socket(needpriv, ai->ai_family);
1.49 markus 297: if (sock < 0)
1.110 markus 298: /* Any error is already output */
1.49 markus 299: continue;
300:
301: if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
302: /* Successful connection. */
1.102 markus 303: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 304: break;
1.49 markus 305: } else {
1.110 markus 306: if (errno == ECONNREFUSED)
307: full_failure = 0;
1.128 itojun 308: #if 0
1.110 markus 309: log("ssh: connect to address %s port %s: %s",
1.123 itojun 310: sockaddr_ntop(ai->ai_addr, ai->ai_addrlen),
311: strport, strerror(errno));
1.128 itojun 312: #endif
1.40 markus 313: /*
314: * Close the failed socket; there appear to
315: * be some problems when reusing a socket for
316: * which connect() has already returned an
317: * error.
318: */
1.38 markus 319: close(sock);
320: }
321: }
1.49 markus 322: if (ai)
323: break; /* Successful connection. */
1.1 deraadt 324:
1.110 markus 325: attempt++;
326: if (attempt >= connection_attempts)
327: break;
1.38 markus 328: /* Sleep a moment before retrying. */
329: sleep(1);
330: }
1.49 markus 331:
332: freeaddrinfo(aitop);
333:
1.38 markus 334: /* Return failure if we didn't get a successful connection. */
335: if (attempt >= connection_attempts)
1.110 markus 336: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.38 markus 337:
338: debug("Connection established.");
339:
1.40 markus 340: /*
341: * Set socket options. We would like the socket to disappear as soon
342: * as it has been closed for whatever reason.
343: */
344: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.38 markus 345: linger.l_onoff = 1;
346: linger.l_linger = 5;
1.90 markus 347: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
348:
349: /* Set keepalives if requested. */
350: if (options.keepalives &&
351: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
352: sizeof(on)) < 0)
353: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 354:
355: /* Set the connection. */
356: packet_set_connection(sock, sock);
1.1 deraadt 357:
1.110 markus 358: return 0;
1.59 markus 359: }
360:
1.43 markus 361: /*
1.39 deraadt 362: * Waits for the server identification string, and sends our own
363: * identification string.
364: */
1.109 itojun 365: static void
1.95 itojun 366: ssh_exchange_identification(void)
1.1 deraadt 367: {
1.38 markus 368: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 369: int remote_major, remote_minor, i, mismatch;
1.38 markus 370: int connection_in = packet_get_connection_in();
371: int connection_out = packet_get_connection_out();
1.93 stevesk 372: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 373:
374: /* Read other side\'s version identification. */
1.75 markus 375: for (;;) {
376: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 377: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 378: if (len < 0)
379: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
380: if (len != 1)
381: fatal("ssh_exchange_identification: Connection closed by remote host");
382: if (buf[i] == '\r') {
383: buf[i] = '\n';
384: buf[i + 1] = 0;
385: continue; /**XXX wait for \n */
386: }
387: if (buf[i] == '\n') {
388: buf[i + 1] = 0;
389: break;
390: }
1.38 markus 391: }
1.75 markus 392: buf[sizeof(buf) - 1] = 0;
1.76 markus 393: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 394: break;
1.75 markus 395: debug("ssh_exchange_identification: %s", buf);
1.38 markus 396: }
1.59 markus 397: server_version_string = xstrdup(buf);
1.38 markus 398:
1.40 markus 399: /*
400: * Check that the versions match. In future this might accept
401: * several versions and set appropriate flags to handle them.
402: */
1.59 markus 403: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
404: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 405: fatal("Bad remote protocol version identification: '%.100s'", buf);
406: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 407: remote_major, remote_minor, remote_version);
1.38 markus 408:
1.59 markus 409: compat_datafellows(remote_version);
1.64 markus 410: mismatch = 0;
1.59 markus 411:
1.116 deraadt 412: switch (remote_major) {
1.64 markus 413: case 1:
414: if (remote_minor == 99 &&
415: (options.protocol & SSH_PROTO_2) &&
416: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
417: enable_compat20();
418: break;
419: }
420: if (!(options.protocol & SSH_PROTO_1)) {
421: mismatch = 1;
422: break;
423: }
424: if (remote_minor < 3) {
425: fatal("Remote machine has too old SSH software version.");
1.81 markus 426: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 427: /* We speak 1.3, too. */
428: enable_compat13();
1.81 markus 429: minor1 = 3;
1.64 markus 430: if (options.forward_agent) {
431: log("Agent forwarding disabled for protocol 1.3");
432: options.forward_agent = 0;
433: }
434: }
435: break;
436: case 2:
437: if (options.protocol & SSH_PROTO_2) {
438: enable_compat20();
439: break;
1.38 markus 440: }
1.64 markus 441: /* FALLTHROUGH */
1.68 markus 442: default:
1.64 markus 443: mismatch = 1;
444: break;
1.38 markus 445: }
1.64 markus 446: if (mismatch)
1.38 markus 447: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 448: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
449: remote_major);
1.38 markus 450: /* Send our own protocol version identification. */
451: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 452: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 453: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 454: SSH_VERSION);
1.45 deraadt 455: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 456: fatal("write: %.100s", strerror(errno));
1.59 markus 457: client_version_string = xstrdup(buf);
458: chop(client_version_string);
459: chop(server_version_string);
460: debug("Local version string %.100s", client_version_string);
1.1 deraadt 461: }
462:
1.96 markus 463: /* defaults to 'no' */
1.109 itojun 464: static int
1.112 markus 465: confirm(const char *prompt)
1.1 deraadt 466: {
1.119 markus 467: const char *msg, *again = "Please type 'yes' or 'no': ";
468: char *p;
469: int ret = -1;
1.96 markus 470:
471: if (options.batch_mode)
472: return 0;
1.119 markus 473: for (msg = prompt;;msg = again) {
474: p = read_passphrase(msg, RP_ECHO);
475: if (p == NULL ||
476: (p[0] == '\0') || (p[0] == '\n') ||
477: strncasecmp(p, "no", 2) == 0)
478: ret = 0;
1.127 markus 479: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 480: ret = 1;
481: if (p)
482: xfree(p);
483: if (ret != -1)
484: return ret;
1.1 deraadt 485: }
486: }
487:
1.39 deraadt 488: /*
1.108 markus 489: * check whether the supplied host key is valid, return -1 if the key
490: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 491: */
1.109 itojun 492: static int
1.70 markus 493: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 494: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 495: {
1.58 markus 496: Key *file_key;
1.72 markus 497: char *type = key_type(host_key);
1.46 markus 498: char *ip = NULL;
1.100 markus 499: char hostline[1000], *hostp, *fp;
1.38 markus 500: HostStatus host_status;
501: HostStatus ip_status;
1.49 markus 502: int local = 0, host_ip_differ = 0;
503: char ntop[NI_MAXHOST];
1.119 markus 504: char msg[1024];
505: int len, host_line, ip_line;
1.85 markus 506: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 507:
508: /*
509: * Force accepting of the host key for loopback/localhost. The
510: * problem is that if the home directory is NFS-mounted to multiple
511: * machines, localhost will refer to a different machine in each of
512: * them, and the user will get bogus HOST_CHANGED warnings. This
513: * essentially disables host authentication for localhost; however,
514: * this is probably not a real problem.
515: */
1.70 markus 516: /** hostaddr == 0! */
1.49 markus 517: switch (hostaddr->sa_family) {
518: case AF_INET:
1.108 markus 519: local = (ntohl(((struct sockaddr_in *)hostaddr)->
520: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 521: break;
522: case AF_INET6:
1.108 markus 523: local = IN6_IS_ADDR_LOOPBACK(
524: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 525: break;
526: default:
527: local = 0;
528: break;
529: }
1.111 markus 530: if (options.no_host_authentication_for_localhost == 1 && local &&
531: options.host_key_alias == NULL) {
1.88 markus 532: debug("Forcing accepting of host key for "
533: "loopback/localhost.");
1.108 markus 534: return 0;
1.49 markus 535: }
1.42 markus 536:
537: /*
1.88 markus 538: * We don't have the remote ip-address for connections
539: * using a proxy command
1.42 markus 540: */
1.84 markus 541: if (options.proxy_command == NULL) {
542: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 543: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 544: fatal("check_host_key: getnameinfo failed");
545: ip = xstrdup(ntop);
546: } else {
547: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 548: }
1.88 markus 549: /*
550: * Turn off check_host_ip if the connection is to localhost, via proxy
551: * command or if we don't have a hostname to compare with
552: */
553: if (options.check_host_ip &&
554: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
555: options.check_host_ip = 0;
1.86 markus 556:
557: /*
558: * Allow the user to record the key under a different name. This is
559: * useful for ssh tunneling over forwarded connections or if you run
560: * multiple sshd's on different ports on the same machine.
561: */
562: if (options.host_key_alias != NULL) {
563: host = options.host_key_alias;
564: debug("using hostkeyalias: %s", host);
1.84 markus 565: }
1.38 markus 566:
1.46 markus 567: /*
568: * Store the host key from the known host file in here so that we can
569: * compare it with the key for the IP address.
570: */
1.58 markus 571: file_key = key_new(host_key->type);
1.38 markus 572:
1.40 markus 573: /*
574: * Check if the host key is present in the user\'s list of known
575: * hosts or in the systemwide list.
576: */
1.85 markus 577: host_file = user_hostfile;
1.108 markus 578: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 579: file_key, &host_line);
1.85 markus 580: if (host_status == HOST_NEW) {
581: host_file = system_hostfile;
1.108 markus 582: host_status = check_host_in_hostfile(host_file, host, host_key,
583: file_key, &host_line);
1.85 markus 584: }
1.40 markus 585: /*
586: * Also perform check for the ip address, skip the check if we are
587: * localhost or the hostname was an ip address to begin with
588: */
1.88 markus 589: if (options.check_host_ip) {
1.58 markus 590: Key *ip_key = key_new(host_key->type);
1.38 markus 591:
1.85 markus 592: ip_file = user_hostfile;
1.108 markus 593: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
594: ip_key, &ip_line);
1.85 markus 595: if (ip_status == HOST_NEW) {
596: ip_file = system_hostfile;
1.108 markus 597: ip_status = check_host_in_hostfile(ip_file, ip,
598: host_key, ip_key, &ip_line);
1.85 markus 599: }
1.38 markus 600: if (host_status == HOST_CHANGED &&
1.58 markus 601: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 602: host_ip_differ = 1;
603:
1.58 markus 604: key_free(ip_key);
1.38 markus 605: } else
606: ip_status = host_status;
607:
1.58 markus 608: key_free(file_key);
1.38 markus 609:
610: switch (host_status) {
611: case HOST_OK:
612: /* The host is known and the key matches. */
1.72 markus 613: debug("Host '%.200s' is known and matches the %s host key.",
614: host, type);
1.85 markus 615: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 616: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 617: if (readonly)
618: log("%s host key for IP address "
619: "'%.128s' not in list of known hosts.",
620: type, ip);
621: else if (!add_host_to_hostfile(user_hostfile, ip,
1.118 deraadt 622: host_key))
1.108 markus 623: log("Failed to add the %s host key for IP "
624: "address '%.128s' to the list of known "
625: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 626: else
1.108 markus 627: log("Warning: Permanently added the %s host "
628: "key for IP address '%.128s' to the list "
629: "of known hosts.", type, ip);
1.38 markus 630: }
631: break;
632: case HOST_NEW:
1.108 markus 633: if (readonly)
634: goto fail;
1.38 markus 635: /* The host is new. */
636: if (options.strict_host_key_checking == 1) {
1.108 markus 637: /*
638: * User has requested strict host key checking. We
639: * will not add the host key automatically. The only
640: * alternative left is to abort.
641: */
642: error("No %s host key is known for %.200s and you "
643: "have requested strict checking.", type, host);
644: goto fail;
1.38 markus 645: } else if (options.strict_host_key_checking == 2) {
646: /* The default */
1.100 markus 647: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.119 markus 648: snprintf(msg, sizeof(msg),
1.108 markus 649: "The authenticity of host '%.200s (%s)' can't be "
650: "established.\n"
1.72 markus 651: "%s key fingerprint is %s.\n"
1.108 markus 652: "Are you sure you want to continue connecting "
653: "(yes/no)? ", host, ip, 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))
1.108 markus 669: log("Failed to add the host to the list of known "
670: "hosts (%.500s).", user_hostfile);
1.38 markus 671: else
1.108 markus 672: log("Warning: Permanently added '%.200s' (%s) to the "
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;
1.88 markus 756: }
757:
758: if (options.check_host_ip && host_status != HOST_CHANGED &&
759: ip_status == HOST_CHANGED) {
1.119 markus 760: snprintf(msg, sizeof(msg),
761: "Warning: the %s host key for '%.200s' "
762: "differs from the key for the IP address '%.128s'"
763: "\nOffending key for IP in %s:%d",
764: type, host, ip, ip_file, ip_line);
765: if (host_status == HOST_OK) {
766: len = strlen(msg);
767: snprintf(msg + len, sizeof(msg) - len,
768: "\nMatching host key in %s:%d",
1.125 deraadt 769: host_file, host_line);
1.119 markus 770: }
1.88 markus 771: if (options.strict_host_key_checking == 1) {
1.119 markus 772: log(msg);
1.108 markus 773: error("Exiting, you have requested strict checking.");
774: goto fail;
1.88 markus 775: } else if (options.strict_host_key_checking == 2) {
1.119 markus 776: strlcat(msg, "\nAre you sure you want "
777: "to continue connecting (yes/no)? ", sizeof(msg));
778: if (!confirm(msg))
1.108 markus 779: goto fail;
1.119 markus 780: } else {
781: log(msg);
1.88 markus 782: }
1.38 markus 783: }
1.82 provos 784:
785: xfree(ip);
1.108 markus 786: return 0;
787:
788: fail:
789: xfree(ip);
790: return -1;
791: }
792:
793: int
794: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
795: {
796: struct stat st;
797:
798: /* return ok if the key can be found in an old keyfile */
799: if (stat(options.system_hostfile2, &st) == 0 ||
800: stat(options.user_hostfile2, &st) == 0) {
801: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
802: options.user_hostfile2, options.system_hostfile2) == 0)
803: return 0;
804: }
805: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
806: options.user_hostfile, options.system_hostfile);
1.51 markus 807: }
1.70 markus 808:
1.51 markus 809: /*
810: * Starts a dialog with the server, and authenticates the current user on the
811: * server. This does not need any extra privileges. The basic connection
812: * to the server must already have been established before this is called.
813: * If login fails, this function prints an error and never returns.
814: * This function does not require super-user privileges.
815: */
816: void
1.120 markus 817: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 818: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 819: {
820: char *host, *cp;
1.70 markus 821: char *server_user, *local_user;
822:
823: local_user = xstrdup(pw->pw_name);
824: server_user = options.user ? options.user : local_user;
1.51 markus 825:
826: /* Convert the user-supplied hostname into all lowercase. */
827: host = xstrdup(orighost);
828: for (cp = host; *cp; cp++)
829: if (isupper(*cp))
830: *cp = tolower(*cp);
831:
832: /* Exchange protocol version identification strings with the server. */
833: ssh_exchange_identification();
834:
835: /* Put the connection into non-blocking mode. */
836: packet_set_nonblocking();
837:
838: /* key exchange */
839: /* authenticate user */
1.59 markus 840: if (compat20) {
841: ssh_kex2(host, hostaddr);
1.120 markus 842: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 843: } else {
844: ssh_kex(host, hostaddr);
1.120 markus 845: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 846: }
1.97 markus 847: }
848:
849: void
850: ssh_put_password(char *password)
851: {
852: int size;
853: char *padded;
854:
1.99 deraadt 855: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 856: packet_put_cstring(password);
1.99 deraadt 857: return;
858: }
1.97 markus 859: size = roundup(strlen(password) + 1, 32);
860: padded = xmalloc(size);
861: memset(padded, 0, size);
862: strlcpy(padded, password, size);
863: packet_put_string(padded, size);
864: memset(padded, 0, size);
865: xfree(padded);
1.1 deraadt 866: }
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