Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.130
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"
1.130 ! itojun 16: RCSID("$OpenBSD: sshconnect.c,v 1.129 2002/07/09 12:04:02 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;
1.40 markus 308: /*
309: * Close the failed socket; there appear to
310: * be some problems when reusing a socket for
311: * which connect() has already returned an
312: * error.
313: */
1.38 markus 314: close(sock);
315: }
316: }
1.49 markus 317: if (ai)
318: break; /* Successful connection. */
1.1 deraadt 319:
1.110 markus 320: attempt++;
321: if (attempt >= connection_attempts)
322: break;
1.38 markus 323: /* Sleep a moment before retrying. */
324: sleep(1);
325: }
1.49 markus 326:
327: freeaddrinfo(aitop);
328:
1.38 markus 329: /* Return failure if we didn't get a successful connection. */
1.130 ! itojun 330: if (attempt >= connection_attempts) {
! 331: log("ssh: connect to host %s port %s: %s",
! 332: host, strport, strerror(errno));
1.110 markus 333: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.130 ! itojun 334: }
1.38 markus 335:
336: debug("Connection established.");
337:
1.40 markus 338: /*
339: * Set socket options. We would like the socket to disappear as soon
340: * as it has been closed for whatever reason.
341: */
342: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.38 markus 343: linger.l_onoff = 1;
344: linger.l_linger = 5;
1.90 markus 345: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
346:
347: /* Set keepalives if requested. */
348: if (options.keepalives &&
349: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
350: sizeof(on)) < 0)
351: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 352:
353: /* Set the connection. */
354: packet_set_connection(sock, sock);
1.1 deraadt 355:
1.110 markus 356: return 0;
1.59 markus 357: }
358:
1.43 markus 359: /*
1.39 deraadt 360: * Waits for the server identification string, and sends our own
361: * identification string.
362: */
1.109 itojun 363: static void
1.95 itojun 364: ssh_exchange_identification(void)
1.1 deraadt 365: {
1.38 markus 366: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 367: int remote_major, remote_minor, i, mismatch;
1.38 markus 368: int connection_in = packet_get_connection_in();
369: int connection_out = packet_get_connection_out();
1.93 stevesk 370: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 371:
372: /* Read other side\'s version identification. */
1.75 markus 373: for (;;) {
374: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 375: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 376: if (len < 0)
377: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
378: if (len != 1)
379: fatal("ssh_exchange_identification: Connection closed by remote host");
380: if (buf[i] == '\r') {
381: buf[i] = '\n';
382: buf[i + 1] = 0;
383: continue; /**XXX wait for \n */
384: }
385: if (buf[i] == '\n') {
386: buf[i + 1] = 0;
387: break;
388: }
1.38 markus 389: }
1.75 markus 390: buf[sizeof(buf) - 1] = 0;
1.76 markus 391: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 392: break;
1.75 markus 393: debug("ssh_exchange_identification: %s", buf);
1.38 markus 394: }
1.59 markus 395: server_version_string = xstrdup(buf);
1.38 markus 396:
1.40 markus 397: /*
398: * Check that the versions match. In future this might accept
399: * several versions and set appropriate flags to handle them.
400: */
1.59 markus 401: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
402: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 403: fatal("Bad remote protocol version identification: '%.100s'", buf);
404: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 405: remote_major, remote_minor, remote_version);
1.38 markus 406:
1.59 markus 407: compat_datafellows(remote_version);
1.64 markus 408: mismatch = 0;
1.59 markus 409:
1.116 deraadt 410: switch (remote_major) {
1.64 markus 411: case 1:
412: if (remote_minor == 99 &&
413: (options.protocol & SSH_PROTO_2) &&
414: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
415: enable_compat20();
416: break;
417: }
418: if (!(options.protocol & SSH_PROTO_1)) {
419: mismatch = 1;
420: break;
421: }
422: if (remote_minor < 3) {
423: fatal("Remote machine has too old SSH software version.");
1.81 markus 424: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 425: /* We speak 1.3, too. */
426: enable_compat13();
1.81 markus 427: minor1 = 3;
1.64 markus 428: if (options.forward_agent) {
429: log("Agent forwarding disabled for protocol 1.3");
430: options.forward_agent = 0;
431: }
432: }
433: break;
434: case 2:
435: if (options.protocol & SSH_PROTO_2) {
436: enable_compat20();
437: break;
1.38 markus 438: }
1.64 markus 439: /* FALLTHROUGH */
1.68 markus 440: default:
1.64 markus 441: mismatch = 1;
442: break;
1.38 markus 443: }
1.64 markus 444: if (mismatch)
1.38 markus 445: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 446: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
447: remote_major);
1.38 markus 448: /* Send our own protocol version identification. */
449: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 450: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 451: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 452: SSH_VERSION);
1.45 deraadt 453: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 454: fatal("write: %.100s", strerror(errno));
1.59 markus 455: client_version_string = xstrdup(buf);
456: chop(client_version_string);
457: chop(server_version_string);
458: debug("Local version string %.100s", client_version_string);
1.1 deraadt 459: }
460:
1.96 markus 461: /* defaults to 'no' */
1.109 itojun 462: static int
1.112 markus 463: confirm(const char *prompt)
1.1 deraadt 464: {
1.119 markus 465: const char *msg, *again = "Please type 'yes' or 'no': ";
466: char *p;
467: int ret = -1;
1.96 markus 468:
469: if (options.batch_mode)
470: return 0;
1.119 markus 471: for (msg = prompt;;msg = again) {
472: p = read_passphrase(msg, RP_ECHO);
473: if (p == NULL ||
474: (p[0] == '\0') || (p[0] == '\n') ||
475: strncasecmp(p, "no", 2) == 0)
476: ret = 0;
1.127 markus 477: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 478: ret = 1;
479: if (p)
480: xfree(p);
481: if (ret != -1)
482: return ret;
1.1 deraadt 483: }
484: }
485:
1.39 deraadt 486: /*
1.108 markus 487: * check whether the supplied host key is valid, return -1 if the key
488: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 489: */
1.109 itojun 490: static int
1.70 markus 491: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 492: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 493: {
1.58 markus 494: Key *file_key;
1.72 markus 495: char *type = key_type(host_key);
1.46 markus 496: char *ip = NULL;
1.100 markus 497: char hostline[1000], *hostp, *fp;
1.38 markus 498: HostStatus host_status;
499: HostStatus ip_status;
1.49 markus 500: int local = 0, host_ip_differ = 0;
501: char ntop[NI_MAXHOST];
1.119 markus 502: char msg[1024];
503: int len, host_line, ip_line;
1.85 markus 504: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 505:
506: /*
507: * Force accepting of the host key for loopback/localhost. The
508: * problem is that if the home directory is NFS-mounted to multiple
509: * machines, localhost will refer to a different machine in each of
510: * them, and the user will get bogus HOST_CHANGED warnings. This
511: * essentially disables host authentication for localhost; however,
512: * this is probably not a real problem.
513: */
1.70 markus 514: /** hostaddr == 0! */
1.49 markus 515: switch (hostaddr->sa_family) {
516: case AF_INET:
1.108 markus 517: local = (ntohl(((struct sockaddr_in *)hostaddr)->
518: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 519: break;
520: case AF_INET6:
1.108 markus 521: local = IN6_IS_ADDR_LOOPBACK(
522: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 523: break;
524: default:
525: local = 0;
526: break;
527: }
1.111 markus 528: if (options.no_host_authentication_for_localhost == 1 && local &&
529: options.host_key_alias == NULL) {
1.88 markus 530: debug("Forcing accepting of host key for "
531: "loopback/localhost.");
1.108 markus 532: return 0;
1.49 markus 533: }
1.42 markus 534:
535: /*
1.88 markus 536: * We don't have the remote ip-address for connections
537: * using a proxy command
1.42 markus 538: */
1.84 markus 539: if (options.proxy_command == NULL) {
540: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 541: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 542: fatal("check_host_key: getnameinfo failed");
543: ip = xstrdup(ntop);
544: } else {
545: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 546: }
1.88 markus 547: /*
548: * Turn off check_host_ip if the connection is to localhost, via proxy
549: * command or if we don't have a hostname to compare with
550: */
551: if (options.check_host_ip &&
552: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
553: options.check_host_ip = 0;
1.86 markus 554:
555: /*
556: * Allow the user to record the key under a different name. This is
557: * useful for ssh tunneling over forwarded connections or if you run
558: * multiple sshd's on different ports on the same machine.
559: */
560: if (options.host_key_alias != NULL) {
561: host = options.host_key_alias;
562: debug("using hostkeyalias: %s", host);
1.84 markus 563: }
1.38 markus 564:
1.46 markus 565: /*
566: * Store the host key from the known host file in here so that we can
567: * compare it with the key for the IP address.
568: */
1.58 markus 569: file_key = key_new(host_key->type);
1.38 markus 570:
1.40 markus 571: /*
572: * Check if the host key is present in the user\'s list of known
573: * hosts or in the systemwide list.
574: */
1.85 markus 575: host_file = user_hostfile;
1.108 markus 576: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 577: file_key, &host_line);
1.85 markus 578: if (host_status == HOST_NEW) {
579: host_file = system_hostfile;
1.108 markus 580: host_status = check_host_in_hostfile(host_file, host, host_key,
581: file_key, &host_line);
1.85 markus 582: }
1.40 markus 583: /*
584: * Also perform check for the ip address, skip the check if we are
585: * localhost or the hostname was an ip address to begin with
586: */
1.88 markus 587: if (options.check_host_ip) {
1.58 markus 588: Key *ip_key = key_new(host_key->type);
1.38 markus 589:
1.85 markus 590: ip_file = user_hostfile;
1.108 markus 591: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
592: ip_key, &ip_line);
1.85 markus 593: if (ip_status == HOST_NEW) {
594: ip_file = system_hostfile;
1.108 markus 595: ip_status = check_host_in_hostfile(ip_file, ip,
596: host_key, ip_key, &ip_line);
1.85 markus 597: }
1.38 markus 598: if (host_status == HOST_CHANGED &&
1.58 markus 599: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 600: host_ip_differ = 1;
601:
1.58 markus 602: key_free(ip_key);
1.38 markus 603: } else
604: ip_status = host_status;
605:
1.58 markus 606: key_free(file_key);
1.38 markus 607:
608: switch (host_status) {
609: case HOST_OK:
610: /* The host is known and the key matches. */
1.72 markus 611: debug("Host '%.200s' is known and matches the %s host key.",
612: host, type);
1.85 markus 613: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 614: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 615: if (readonly)
616: log("%s host key for IP address "
617: "'%.128s' not in list of known hosts.",
618: type, ip);
619: else if (!add_host_to_hostfile(user_hostfile, ip,
1.118 deraadt 620: host_key))
1.108 markus 621: log("Failed to add the %s host key for IP "
622: "address '%.128s' to the list of known "
623: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 624: else
1.108 markus 625: log("Warning: Permanently added the %s host "
626: "key for IP address '%.128s' to the list "
627: "of known hosts.", type, ip);
1.38 markus 628: }
629: break;
630: case HOST_NEW:
1.108 markus 631: if (readonly)
632: goto fail;
1.38 markus 633: /* The host is new. */
634: if (options.strict_host_key_checking == 1) {
1.108 markus 635: /*
636: * User has requested strict host key checking. We
637: * will not add the host key automatically. The only
638: * alternative left is to abort.
639: */
640: error("No %s host key is known for %.200s and you "
641: "have requested strict checking.", type, host);
642: goto fail;
1.38 markus 643: } else if (options.strict_host_key_checking == 2) {
644: /* The default */
1.100 markus 645: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.119 markus 646: snprintf(msg, sizeof(msg),
1.108 markus 647: "The authenticity of host '%.200s (%s)' can't be "
648: "established.\n"
1.72 markus 649: "%s key fingerprint is %s.\n"
1.108 markus 650: "Are you sure you want to continue connecting "
651: "(yes/no)? ", host, ip, type, fp);
1.100 markus 652: xfree(fp);
1.119 markus 653: if (!confirm(msg))
1.108 markus 654: goto fail;
1.38 markus 655: }
1.88 markus 656: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 657: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
658: hostp = hostline;
659: } else
660: hostp = host;
661:
1.108 markus 662: /*
663: * If not in strict mode, add the key automatically to the
664: * local known_hosts file.
665: */
1.70 markus 666: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.108 markus 667: log("Failed to add the host to the list of known "
668: "hosts (%.500s).", user_hostfile);
1.38 markus 669: else
1.108 markus 670: log("Warning: Permanently added '%.200s' (%s) to the "
671: "list of known hosts.", hostp, type);
1.38 markus 672: break;
673: case HOST_CHANGED:
674: if (options.check_host_ip && host_ip_differ) {
675: char *msg;
676: if (ip_status == HOST_NEW)
677: msg = "is unknown";
678: else if (ip_status == HOST_OK)
679: msg = "is unchanged";
680: else
681: msg = "has a different value";
682: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
683: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
684: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 685: error("The %s host key for %s has changed,", type, host);
1.38 markus 686: error("and the key for the according IP address %s", ip);
687: error("%s. This could either mean that", msg);
688: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 689: error("and its host key have changed at the same time.");
1.88 markus 690: if (ip_status != HOST_NEW)
1.85 markus 691: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 692: }
693: /* The host key has changed. */
1.100 markus 694: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 695: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 696: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 697: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
698: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
699: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 700: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 701: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.100 markus 702: type, fp);
1.38 markus 703: error("Please contact your system administrator.");
704: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 705: user_hostfile);
1.85 markus 706: error("Offending key in %s:%d", host_file, host_line);
1.100 markus 707: xfree(fp);
1.38 markus 708:
1.40 markus 709: /*
710: * If strict host key checking is in use, the user will have
711: * to edit the key manually and we can only abort.
712: */
1.108 markus 713: if (options.strict_host_key_checking) {
714: error("%s host key for %.200s has changed and you have "
715: "requested strict checking.", type, host);
716: goto fail;
717: }
1.38 markus 718:
1.40 markus 719: /*
720: * If strict host key checking has not been requested, allow
721: * the connection but without password authentication or
722: * agent forwarding.
723: */
1.38 markus 724: if (options.password_authentication) {
1.108 markus 725: error("Password authentication is disabled to avoid "
726: "man-in-the-middle attacks.");
1.38 markus 727: options.password_authentication = 0;
728: }
729: if (options.forward_agent) {
1.108 markus 730: error("Agent forwarding is disabled to avoid "
731: "man-in-the-middle attacks.");
1.38 markus 732: options.forward_agent = 0;
1.83 markus 733: }
734: if (options.forward_x11) {
1.108 markus 735: error("X11 forwarding is disabled to avoid "
736: "man-in-the-middle attacks.");
1.83 markus 737: options.forward_x11 = 0;
738: }
1.108 markus 739: if (options.num_local_forwards > 0 ||
740: options.num_remote_forwards > 0) {
741: error("Port forwarding is disabled to avoid "
742: "man-in-the-middle attacks.");
743: options.num_local_forwards =
1.118 deraadt 744: options.num_remote_forwards = 0;
1.38 markus 745: }
1.40 markus 746: /*
747: * XXX Should permit the user to change to use the new id.
748: * This could be done by converting the host key to an
749: * identifying sentence, tell that the host identifies itself
750: * by that sentence, and ask the user if he/she whishes to
751: * accept the authentication.
752: */
1.38 markus 753: break;
1.88 markus 754: }
755:
756: if (options.check_host_ip && host_status != HOST_CHANGED &&
757: ip_status == HOST_CHANGED) {
1.119 markus 758: snprintf(msg, sizeof(msg),
759: "Warning: the %s host key for '%.200s' "
760: "differs from the key for the IP address '%.128s'"
761: "\nOffending key for IP in %s:%d",
762: type, host, ip, ip_file, ip_line);
763: if (host_status == HOST_OK) {
764: len = strlen(msg);
765: snprintf(msg + len, sizeof(msg) - len,
766: "\nMatching host key in %s:%d",
1.125 deraadt 767: host_file, host_line);
1.119 markus 768: }
1.88 markus 769: if (options.strict_host_key_checking == 1) {
1.119 markus 770: log(msg);
1.108 markus 771: error("Exiting, you have requested strict checking.");
772: goto fail;
1.88 markus 773: } else if (options.strict_host_key_checking == 2) {
1.119 markus 774: strlcat(msg, "\nAre you sure you want "
775: "to continue connecting (yes/no)? ", sizeof(msg));
776: if (!confirm(msg))
1.108 markus 777: goto fail;
1.119 markus 778: } else {
779: log(msg);
1.88 markus 780: }
1.38 markus 781: }
1.82 provos 782:
783: xfree(ip);
1.108 markus 784: return 0;
785:
786: fail:
787: xfree(ip);
788: return -1;
789: }
790:
791: int
792: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
793: {
794: struct stat st;
795:
796: /* return ok if the key can be found in an old keyfile */
797: if (stat(options.system_hostfile2, &st) == 0 ||
798: stat(options.user_hostfile2, &st) == 0) {
799: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
800: options.user_hostfile2, options.system_hostfile2) == 0)
801: return 0;
802: }
803: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
804: options.user_hostfile, options.system_hostfile);
1.51 markus 805: }
1.70 markus 806:
1.51 markus 807: /*
808: * Starts a dialog with the server, and authenticates the current user on the
809: * server. This does not need any extra privileges. The basic connection
810: * to the server must already have been established before this is called.
811: * If login fails, this function prints an error and never returns.
812: * This function does not require super-user privileges.
813: */
814: void
1.120 markus 815: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 816: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 817: {
818: char *host, *cp;
1.70 markus 819: char *server_user, *local_user;
820:
821: local_user = xstrdup(pw->pw_name);
822: server_user = options.user ? options.user : local_user;
1.51 markus 823:
824: /* Convert the user-supplied hostname into all lowercase. */
825: host = xstrdup(orighost);
826: for (cp = host; *cp; cp++)
827: if (isupper(*cp))
828: *cp = tolower(*cp);
829:
830: /* Exchange protocol version identification strings with the server. */
831: ssh_exchange_identification();
832:
833: /* Put the connection into non-blocking mode. */
834: packet_set_nonblocking();
835:
836: /* key exchange */
837: /* authenticate user */
1.59 markus 838: if (compat20) {
839: ssh_kex2(host, hostaddr);
1.120 markus 840: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 841: } else {
842: ssh_kex(host, hostaddr);
1.120 markus 843: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 844: }
1.97 markus 845: }
846:
847: void
848: ssh_put_password(char *password)
849: {
850: int size;
851: char *padded;
852:
1.99 deraadt 853: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 854: packet_put_cstring(password);
1.99 deraadt 855: return;
856: }
1.97 markus 857: size = roundup(strlen(password) + 1, 32);
858: padded = xmalloc(size);
859: memset(padded, 0, size);
860: strlcpy(padded, password, size);
861: packet_put_string(padded, size);
862: memset(padded, 0, size);
863: xfree(padded);
1.1 deraadt 864: }
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