Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.127
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"
1.127 ! markus 16: RCSID("$OpenBSD: sshconnect.c,v 1.126 2002/06/23 03:30:17 deraadt 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:
1.110 markus 45: static const char *
1.123 itojun 46: sockaddr_ntop(struct sockaddr *sa, socklen_t salen)
1.110 markus 47: {
1.121 itojun 48: static char addrbuf[NI_MAXHOST];
1.110 markus 49:
1.123 itojun 50: if (getnameinfo(sa, salen, addrbuf, sizeof(addrbuf), NULL, 0,
1.121 itojun 51: NI_NUMERICHOST) != 0)
1.122 markus 52: fatal("sockaddr_ntop: getnameinfo NI_NUMERICHOST failed");
1.110 markus 53: return addrbuf;
54: }
55:
1.39 deraadt 56: /*
57: * Connect to the given ssh server using a proxy command.
58: */
1.109 itojun 59: static int
1.124 markus 60: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 61: {
1.38 markus 62: Buffer command;
63: const char *cp;
64: char *command_string;
65: int pin[2], pout[2];
1.69 deraadt 66: pid_t pid;
1.49 markus 67: char strport[NI_MAXSERV];
1.38 markus 68:
69: /* Convert the port number into a string. */
1.49 markus 70: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 71:
72: /* Build the final command string in the buffer by making the
73: appropriate substitutions to the given proxy command. */
74: buffer_init(&command);
75: for (cp = proxy_command; *cp; cp++) {
76: if (cp[0] == '%' && cp[1] == '%') {
77: buffer_append(&command, "%", 1);
78: cp++;
79: continue;
80: }
81: if (cp[0] == '%' && cp[1] == 'h') {
82: buffer_append(&command, host, strlen(host));
83: cp++;
84: continue;
85: }
86: if (cp[0] == '%' && cp[1] == 'p') {
1.49 markus 87: buffer_append(&command, strport, strlen(strport));
1.38 markus 88: cp++;
89: continue;
90: }
91: buffer_append(&command, cp, 1);
92: }
93: buffer_append(&command, "\0", 1);
94:
95: /* Get the final command string. */
96: command_string = buffer_ptr(&command);
97:
98: /* Create pipes for communicating with the proxy. */
99: if (pipe(pin) < 0 || pipe(pout) < 0)
100: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 101: strerror(errno));
1.38 markus 102:
103: debug("Executing proxy command: %.500s", command_string);
104:
105: /* Fork and execute the proxy command. */
106: if ((pid = fork()) == 0) {
107: char *argv[10];
108:
109: /* Child. Permanently give up superuser privileges. */
1.124 markus 110: seteuid(original_real_uid);
111: setuid(original_real_uid);
1.38 markus 112:
113: /* Redirect stdin and stdout. */
114: close(pin[1]);
115: if (pin[0] != 0) {
116: if (dup2(pin[0], 0) < 0)
117: perror("dup2 stdin");
118: close(pin[0]);
119: }
120: close(pout[0]);
121: if (dup2(pout[1], 1) < 0)
122: perror("dup2 stdout");
123: /* Cannot be 1 because pin allocated two descriptors. */
124: close(pout[1]);
125:
126: /* Stderr is left as it is so that error messages get
127: printed on the user's terminal. */
1.89 markus 128: argv[0] = _PATH_BSHELL;
1.38 markus 129: argv[1] = "-c";
130: argv[2] = command_string;
131: argv[3] = NULL;
132:
133: /* Execute the proxy command. Note that we gave up any
134: extra privileges above. */
1.89 markus 135: execv(argv[0], argv);
136: perror(argv[0]);
1.38 markus 137: exit(1);
138: }
139: /* Parent. */
140: if (pid < 0)
141: fatal("fork failed: %.100s", strerror(errno));
142:
143: /* Close child side of the descriptors. */
144: close(pin[0]);
145: close(pout[1]);
146:
147: /* Free the command name. */
148: buffer_free(&command);
149:
150: /* Set the connection file descriptors. */
151: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 152:
1.110 markus 153: /* Indicate OK return */
154: return 0;
1.1 deraadt 155: }
156:
1.39 deraadt 157: /*
158: * Creates a (possibly privileged) socket for use as the ssh connection.
159: */
1.109 itojun 160: static int
1.124 markus 161: ssh_create_socket(int privileged, int family)
1.1 deraadt 162: {
1.105 markus 163: int sock, gaierr;
164: struct addrinfo hints, *res;
1.1 deraadt 165:
1.40 markus 166: /*
167: * If we are running as root and want to connect to a privileged
168: * port, bind our own socket to a privileged port.
169: */
1.38 markus 170: if (privileged) {
171: int p = IPPORT_RESERVED - 1;
1.124 markus 172: PRIV_START;
1.49 markus 173: sock = rresvport_af(&p, family);
1.124 markus 174: PRIV_END;
1.38 markus 175: if (sock < 0)
1.55 markus 176: error("rresvport: af=%d %.100s", family, strerror(errno));
177: else
178: debug("Allocated local port %d.", p);
1.105 markus 179: return sock;
180: }
181: sock = socket(family, SOCK_STREAM, 0);
182: if (sock < 0)
183: error("socket: %.100s", strerror(errno));
184:
185: /* Bind the socket to an alternative local IP address */
186: if (options.bind_address == NULL)
187: return sock;
188:
189: memset(&hints, 0, sizeof(hints));
1.114 markus 190: hints.ai_family = family;
1.105 markus 191: hints.ai_socktype = SOCK_STREAM;
192: hints.ai_flags = AI_PASSIVE;
193: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
194: if (gaierr) {
195: error("getaddrinfo: %s: %s", options.bind_address,
196: gai_strerror(gaierr));
197: close(sock);
198: return -1;
199: }
200: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
201: error("bind: %s: %s", options.bind_address, strerror(errno));
202: close(sock);
203: freeaddrinfo(res);
204: return -1;
1.38 markus 205: }
1.105 markus 206: freeaddrinfo(res);
1.38 markus 207: return sock;
1.1 deraadt 208: }
209:
1.39 deraadt 210: /*
1.49 markus 211: * Opens a TCP/IP connection to the remote server on the given host.
212: * The address of the remote host will be returned in hostaddr.
1.124 markus 213: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 214: * a privileged port will be allocated to make the connection.
1.124 markus 215: * This requires super-user privileges if needpriv is true.
1.39 deraadt 216: * Connection_attempts specifies the maximum number of tries (one per
217: * second). If proxy_command is non-NULL, it specifies the command (with %h
218: * and %p substituted for host and port, respectively) to use to contact
219: * the daemon.
1.110 markus 220: * Return values:
221: * 0 for OK
222: * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
223: * ECONNABORTED if we failed without a "Connection refused"
224: * Suitable error messages for the connection failure will already have been
225: * printed.
1.39 deraadt 226: */
1.38 markus 227: int
1.49 markus 228: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 229: u_short port, int family, int connection_attempts,
1.124 markus 230: int needpriv, const char *proxy_command)
1.1 deraadt 231: {
1.90 markus 232: int gaierr;
233: int on = 1;
1.49 markus 234: int sock = -1, attempt;
1.90 markus 235: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 236: struct addrinfo hints, *ai, *aitop;
1.38 markus 237: struct linger linger;
1.90 markus 238: struct servent *sp;
1.110 markus 239: /*
240: * Did we get only other errors than "Connection refused" (which
241: * should block fallback to rsh and similar), or did we get at least
242: * one "Connection refused"?
243: */
244: int full_failure = 1;
1.38 markus 245:
1.124 markus 246: debug("ssh_connect: needpriv %d", needpriv);
1.38 markus 247:
248: /* Get default port if port has not been set. */
249: if (port == 0) {
250: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
251: if (sp)
252: port = ntohs(sp->s_port);
253: else
254: port = SSH_DEFAULT_PORT;
255: }
256: /* If a proxy command is given, connect using it. */
257: if (proxy_command != NULL)
1.124 markus 258: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 259:
260: /* No proxy command. */
261:
1.49 markus 262: memset(&hints, 0, sizeof(hints));
1.115 markus 263: hints.ai_family = family;
1.49 markus 264: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 265: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 266: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 267: fatal("%s: %.100s: %s", __progname, host,
268: gai_strerror(gaierr));
1.38 markus 269:
1.46 markus 270: /*
271: * Try to connect several times. On some machines, the first time
272: * will sometimes fail. In general socket code appears to behave
273: * quite magically on many machines.
1.110 markus 274: */
275: for (attempt = 0; ;) {
1.38 markus 276: if (attempt > 0)
277: debug("Trying again...");
278:
1.49 markus 279: /* Loop through addresses for this host, and try each one in
1.68 markus 280: sequence until the connection succeeds. */
1.49 markus 281: for (ai = aitop; ai; ai = ai->ai_next) {
282: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
283: continue;
284: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
285: ntop, sizeof(ntop), strport, sizeof(strport),
286: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
287: error("ssh_connect: getnameinfo failed");
288: continue;
289: }
290: debug("Connecting to %.200s [%.100s] port %s.",
291: host, ntop, strport);
292:
293: /* Create a socket for connecting. */
1.124 markus 294: sock = ssh_create_socket(needpriv, ai->ai_family);
1.49 markus 295: if (sock < 0)
1.110 markus 296: /* Any error is already output */
1.49 markus 297: continue;
298:
299: if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
300: /* Successful connection. */
1.102 markus 301: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 302: break;
1.49 markus 303: } else {
1.110 markus 304: if (errno == ECONNREFUSED)
305: full_failure = 0;
306: log("ssh: connect to address %s port %s: %s",
1.123 itojun 307: sockaddr_ntop(ai->ai_addr, ai->ai_addrlen),
308: strport, strerror(errno));
1.40 markus 309: /*
310: * Close the failed socket; there appear to
311: * be some problems when reusing a socket for
312: * which connect() has already returned an
313: * error.
314: */
1.38 markus 315: close(sock);
316: }
317: }
1.49 markus 318: if (ai)
319: break; /* Successful connection. */
1.1 deraadt 320:
1.110 markus 321: attempt++;
322: if (attempt >= connection_attempts)
323: break;
1.38 markus 324: /* Sleep a moment before retrying. */
325: sleep(1);
326: }
1.49 markus 327:
328: freeaddrinfo(aitop);
329:
1.38 markus 330: /* Return failure if we didn't get a successful connection. */
331: if (attempt >= connection_attempts)
1.110 markus 332: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.38 markus 333:
334: debug("Connection established.");
335:
1.40 markus 336: /*
337: * Set socket options. We would like the socket to disappear as soon
338: * as it has been closed for whatever reason.
339: */
340: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.38 markus 341: linger.l_onoff = 1;
342: linger.l_linger = 5;
1.90 markus 343: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
344:
345: /* Set keepalives if requested. */
346: if (options.keepalives &&
347: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
348: sizeof(on)) < 0)
349: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 350:
351: /* Set the connection. */
352: packet_set_connection(sock, sock);
1.1 deraadt 353:
1.110 markus 354: return 0;
1.59 markus 355: }
356:
1.43 markus 357: /*
1.39 deraadt 358: * Waits for the server identification string, and sends our own
359: * identification string.
360: */
1.109 itojun 361: static void
1.95 itojun 362: ssh_exchange_identification(void)
1.1 deraadt 363: {
1.38 markus 364: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 365: int remote_major, remote_minor, i, mismatch;
1.38 markus 366: int connection_in = packet_get_connection_in();
367: int connection_out = packet_get_connection_out();
1.93 stevesk 368: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 369:
370: /* Read other side\'s version identification. */
1.75 markus 371: for (;;) {
372: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 373: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 374: if (len < 0)
375: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
376: if (len != 1)
377: fatal("ssh_exchange_identification: Connection closed by remote host");
378: if (buf[i] == '\r') {
379: buf[i] = '\n';
380: buf[i + 1] = 0;
381: continue; /**XXX wait for \n */
382: }
383: if (buf[i] == '\n') {
384: buf[i + 1] = 0;
385: break;
386: }
1.38 markus 387: }
1.75 markus 388: buf[sizeof(buf) - 1] = 0;
1.76 markus 389: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 390: break;
1.75 markus 391: debug("ssh_exchange_identification: %s", buf);
1.38 markus 392: }
1.59 markus 393: server_version_string = xstrdup(buf);
1.38 markus 394:
1.40 markus 395: /*
396: * Check that the versions match. In future this might accept
397: * several versions and set appropriate flags to handle them.
398: */
1.59 markus 399: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
400: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 401: fatal("Bad remote protocol version identification: '%.100s'", buf);
402: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 403: remote_major, remote_minor, remote_version);
1.38 markus 404:
1.59 markus 405: compat_datafellows(remote_version);
1.64 markus 406: mismatch = 0;
1.59 markus 407:
1.116 deraadt 408: switch (remote_major) {
1.64 markus 409: case 1:
410: if (remote_minor == 99 &&
411: (options.protocol & SSH_PROTO_2) &&
412: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
413: enable_compat20();
414: break;
415: }
416: if (!(options.protocol & SSH_PROTO_1)) {
417: mismatch = 1;
418: break;
419: }
420: if (remote_minor < 3) {
421: fatal("Remote machine has too old SSH software version.");
1.81 markus 422: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 423: /* We speak 1.3, too. */
424: enable_compat13();
1.81 markus 425: minor1 = 3;
1.64 markus 426: if (options.forward_agent) {
427: log("Agent forwarding disabled for protocol 1.3");
428: options.forward_agent = 0;
429: }
430: }
431: break;
432: case 2:
433: if (options.protocol & SSH_PROTO_2) {
434: enable_compat20();
435: break;
1.38 markus 436: }
1.64 markus 437: /* FALLTHROUGH */
1.68 markus 438: default:
1.64 markus 439: mismatch = 1;
440: break;
1.38 markus 441: }
1.64 markus 442: if (mismatch)
1.38 markus 443: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 444: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
445: remote_major);
1.38 markus 446: /* Send our own protocol version identification. */
447: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 448: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 449: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 450: SSH_VERSION);
1.45 deraadt 451: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 452: fatal("write: %.100s", strerror(errno));
1.59 markus 453: client_version_string = xstrdup(buf);
454: chop(client_version_string);
455: chop(server_version_string);
456: debug("Local version string %.100s", client_version_string);
1.1 deraadt 457: }
458:
1.96 markus 459: /* defaults to 'no' */
1.109 itojun 460: static int
1.112 markus 461: confirm(const char *prompt)
1.1 deraadt 462: {
1.119 markus 463: const char *msg, *again = "Please type 'yes' or 'no': ";
464: char *p;
465: int ret = -1;
1.96 markus 466:
467: if (options.batch_mode)
468: return 0;
1.119 markus 469: for (msg = prompt;;msg = again) {
470: p = read_passphrase(msg, RP_ECHO);
471: if (p == NULL ||
472: (p[0] == '\0') || (p[0] == '\n') ||
473: strncasecmp(p, "no", 2) == 0)
474: ret = 0;
1.127 ! markus 475: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 476: ret = 1;
477: if (p)
478: xfree(p);
479: if (ret != -1)
480: return ret;
1.1 deraadt 481: }
482: }
483:
1.39 deraadt 484: /*
1.108 markus 485: * check whether the supplied host key is valid, return -1 if the key
486: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 487: */
1.109 itojun 488: static int
1.70 markus 489: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 490: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 491: {
1.58 markus 492: Key *file_key;
1.72 markus 493: char *type = key_type(host_key);
1.46 markus 494: char *ip = NULL;
1.100 markus 495: char hostline[1000], *hostp, *fp;
1.38 markus 496: HostStatus host_status;
497: HostStatus ip_status;
1.49 markus 498: int local = 0, host_ip_differ = 0;
499: char ntop[NI_MAXHOST];
1.119 markus 500: char msg[1024];
501: int len, host_line, ip_line;
1.85 markus 502: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 503:
504: /*
505: * Force accepting of the host key for loopback/localhost. The
506: * problem is that if the home directory is NFS-mounted to multiple
507: * machines, localhost will refer to a different machine in each of
508: * them, and the user will get bogus HOST_CHANGED warnings. This
509: * essentially disables host authentication for localhost; however,
510: * this is probably not a real problem.
511: */
1.70 markus 512: /** hostaddr == 0! */
1.49 markus 513: switch (hostaddr->sa_family) {
514: case AF_INET:
1.108 markus 515: local = (ntohl(((struct sockaddr_in *)hostaddr)->
516: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 517: break;
518: case AF_INET6:
1.108 markus 519: local = IN6_IS_ADDR_LOOPBACK(
520: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 521: break;
522: default:
523: local = 0;
524: break;
525: }
1.111 markus 526: if (options.no_host_authentication_for_localhost == 1 && local &&
527: options.host_key_alias == NULL) {
1.88 markus 528: debug("Forcing accepting of host key for "
529: "loopback/localhost.");
1.108 markus 530: return 0;
1.49 markus 531: }
1.42 markus 532:
533: /*
1.88 markus 534: * We don't have the remote ip-address for connections
535: * using a proxy command
1.42 markus 536: */
1.84 markus 537: if (options.proxy_command == NULL) {
538: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 539: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 540: fatal("check_host_key: getnameinfo failed");
541: ip = xstrdup(ntop);
542: } else {
543: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 544: }
1.88 markus 545: /*
546: * Turn off check_host_ip if the connection is to localhost, via proxy
547: * command or if we don't have a hostname to compare with
548: */
549: if (options.check_host_ip &&
550: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
551: options.check_host_ip = 0;
1.86 markus 552:
553: /*
554: * Allow the user to record the key under a different name. This is
555: * useful for ssh tunneling over forwarded connections or if you run
556: * multiple sshd's on different ports on the same machine.
557: */
558: if (options.host_key_alias != NULL) {
559: host = options.host_key_alias;
560: debug("using hostkeyalias: %s", host);
1.84 markus 561: }
1.38 markus 562:
1.46 markus 563: /*
564: * Store the host key from the known host file in here so that we can
565: * compare it with the key for the IP address.
566: */
1.58 markus 567: file_key = key_new(host_key->type);
1.38 markus 568:
1.40 markus 569: /*
570: * Check if the host key is present in the user\'s list of known
571: * hosts or in the systemwide list.
572: */
1.85 markus 573: host_file = user_hostfile;
1.108 markus 574: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 575: file_key, &host_line);
1.85 markus 576: if (host_status == HOST_NEW) {
577: host_file = system_hostfile;
1.108 markus 578: host_status = check_host_in_hostfile(host_file, host, host_key,
579: file_key, &host_line);
1.85 markus 580: }
1.40 markus 581: /*
582: * Also perform check for the ip address, skip the check if we are
583: * localhost or the hostname was an ip address to begin with
584: */
1.88 markus 585: if (options.check_host_ip) {
1.58 markus 586: Key *ip_key = key_new(host_key->type);
1.38 markus 587:
1.85 markus 588: ip_file = user_hostfile;
1.108 markus 589: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
590: ip_key, &ip_line);
1.85 markus 591: if (ip_status == HOST_NEW) {
592: ip_file = system_hostfile;
1.108 markus 593: ip_status = check_host_in_hostfile(ip_file, ip,
594: host_key, ip_key, &ip_line);
1.85 markus 595: }
1.38 markus 596: if (host_status == HOST_CHANGED &&
1.58 markus 597: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 598: host_ip_differ = 1;
599:
1.58 markus 600: key_free(ip_key);
1.38 markus 601: } else
602: ip_status = host_status;
603:
1.58 markus 604: key_free(file_key);
1.38 markus 605:
606: switch (host_status) {
607: case HOST_OK:
608: /* The host is known and the key matches. */
1.72 markus 609: debug("Host '%.200s' is known and matches the %s host key.",
610: host, type);
1.85 markus 611: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 612: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 613: if (readonly)
614: log("%s host key for IP address "
615: "'%.128s' not in list of known hosts.",
616: type, ip);
617: else if (!add_host_to_hostfile(user_hostfile, ip,
1.118 deraadt 618: host_key))
1.108 markus 619: log("Failed to add the %s host key for IP "
620: "address '%.128s' to the list of known "
621: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 622: else
1.108 markus 623: log("Warning: Permanently added the %s host "
624: "key for IP address '%.128s' to the list "
625: "of known hosts.", type, ip);
1.38 markus 626: }
627: break;
628: case HOST_NEW:
1.108 markus 629: if (readonly)
630: goto fail;
1.38 markus 631: /* The host is new. */
632: if (options.strict_host_key_checking == 1) {
1.108 markus 633: /*
634: * User has requested strict host key checking. We
635: * will not add the host key automatically. The only
636: * alternative left is to abort.
637: */
638: error("No %s host key is known for %.200s and you "
639: "have requested strict checking.", type, host);
640: goto fail;
1.38 markus 641: } else if (options.strict_host_key_checking == 2) {
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 "
646: "established.\n"
1.72 markus 647: "%s key fingerprint is %s.\n"
1.108 markus 648: "Are you sure you want to continue connecting "
649: "(yes/no)? ", host, ip, type, fp);
1.100 markus 650: xfree(fp);
1.119 markus 651: if (!confirm(msg))
1.108 markus 652: goto fail;
1.38 markus 653: }
1.88 markus 654: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 655: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
656: hostp = hostline;
657: } else
658: hostp = host;
659:
1.108 markus 660: /*
661: * If not in strict mode, add the key automatically to the
662: * local known_hosts file.
663: */
1.70 markus 664: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.108 markus 665: log("Failed to add the host to the list of known "
666: "hosts (%.500s).", user_hostfile);
1.38 markus 667: else
1.108 markus 668: log("Warning: Permanently added '%.200s' (%s) to the "
669: "list of known hosts.", hostp, type);
1.38 markus 670: break;
671: case HOST_CHANGED:
672: if (options.check_host_ip && host_ip_differ) {
673: char *msg;
674: if (ip_status == HOST_NEW)
675: msg = "is unknown";
676: else if (ip_status == HOST_OK)
677: msg = "is unchanged";
678: else
679: msg = "has a different value";
680: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
681: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
682: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 683: error("The %s host key for %s has changed,", type, host);
1.38 markus 684: error("and the key for the according IP address %s", ip);
685: error("%s. This could either mean that", msg);
686: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 687: error("and its host key have changed at the same time.");
1.88 markus 688: if (ip_status != HOST_NEW)
1.85 markus 689: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 690: }
691: /* The host key has changed. */
1.100 markus 692: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 693: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 694: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 695: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
696: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
697: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 698: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 699: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.100 markus 700: type, fp);
1.38 markus 701: error("Please contact your system administrator.");
702: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 703: user_hostfile);
1.85 markus 704: error("Offending key in %s:%d", host_file, host_line);
1.100 markus 705: xfree(fp);
1.38 markus 706:
1.40 markus 707: /*
708: * If strict host key checking is in use, the user will have
709: * to edit the key manually and we can only abort.
710: */
1.108 markus 711: if (options.strict_host_key_checking) {
712: error("%s host key for %.200s has changed and you have "
713: "requested strict checking.", type, host);
714: goto fail;
715: }
1.38 markus 716:
1.40 markus 717: /*
718: * If strict host key checking has not been requested, allow
719: * the connection but without password authentication or
720: * agent forwarding.
721: */
1.38 markus 722: if (options.password_authentication) {
1.108 markus 723: error("Password authentication is disabled to avoid "
724: "man-in-the-middle attacks.");
1.38 markus 725: options.password_authentication = 0;
726: }
727: if (options.forward_agent) {
1.108 markus 728: error("Agent forwarding is disabled to avoid "
729: "man-in-the-middle attacks.");
1.38 markus 730: options.forward_agent = 0;
1.83 markus 731: }
732: if (options.forward_x11) {
1.108 markus 733: error("X11 forwarding is disabled to avoid "
734: "man-in-the-middle attacks.");
1.83 markus 735: options.forward_x11 = 0;
736: }
1.108 markus 737: if (options.num_local_forwards > 0 ||
738: options.num_remote_forwards > 0) {
739: error("Port forwarding is disabled to avoid "
740: "man-in-the-middle attacks.");
741: options.num_local_forwards =
1.118 deraadt 742: options.num_remote_forwards = 0;
1.38 markus 743: }
1.40 markus 744: /*
745: * XXX Should permit the user to change to use the new id.
746: * This could be done by converting the host key to an
747: * identifying sentence, tell that the host identifies itself
748: * by that sentence, and ask the user if he/she whishes to
749: * accept the authentication.
750: */
1.38 markus 751: break;
1.88 markus 752: }
753:
754: if (options.check_host_ip && host_status != HOST_CHANGED &&
755: ip_status == HOST_CHANGED) {
1.119 markus 756: snprintf(msg, sizeof(msg),
757: "Warning: the %s host key for '%.200s' "
758: "differs from the key for the IP address '%.128s'"
759: "\nOffending key for IP in %s:%d",
760: type, host, ip, ip_file, ip_line);
761: if (host_status == HOST_OK) {
762: len = strlen(msg);
763: snprintf(msg + len, sizeof(msg) - len,
764: "\nMatching host key in %s:%d",
1.125 deraadt 765: host_file, host_line);
1.119 markus 766: }
1.88 markus 767: if (options.strict_host_key_checking == 1) {
1.119 markus 768: log(msg);
1.108 markus 769: error("Exiting, you have requested strict checking.");
770: goto fail;
1.88 markus 771: } else if (options.strict_host_key_checking == 2) {
1.119 markus 772: strlcat(msg, "\nAre you sure you want "
773: "to continue connecting (yes/no)? ", sizeof(msg));
774: if (!confirm(msg))
1.108 markus 775: goto fail;
1.119 markus 776: } else {
777: log(msg);
1.88 markus 778: }
1.38 markus 779: }
1.82 provos 780:
781: xfree(ip);
1.108 markus 782: return 0;
783:
784: fail:
785: xfree(ip);
786: return -1;
787: }
788:
789: int
790: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
791: {
792: struct stat st;
793:
794: /* return ok if the key can be found in an old keyfile */
795: if (stat(options.system_hostfile2, &st) == 0 ||
796: stat(options.user_hostfile2, &st) == 0) {
797: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
798: options.user_hostfile2, options.system_hostfile2) == 0)
799: return 0;
800: }
801: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
802: options.user_hostfile, options.system_hostfile);
1.51 markus 803: }
1.70 markus 804:
1.51 markus 805: /*
806: * Starts a dialog with the server, and authenticates the current user on the
807: * server. This does not need any extra privileges. The basic connection
808: * to the server must already have been established before this is called.
809: * If login fails, this function prints an error and never returns.
810: * This function does not require super-user privileges.
811: */
812: void
1.120 markus 813: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 814: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 815: {
816: char *host, *cp;
1.70 markus 817: char *server_user, *local_user;
818:
819: local_user = xstrdup(pw->pw_name);
820: server_user = options.user ? options.user : local_user;
1.51 markus 821:
822: /* Convert the user-supplied hostname into all lowercase. */
823: host = xstrdup(orighost);
824: for (cp = host; *cp; cp++)
825: if (isupper(*cp))
826: *cp = tolower(*cp);
827:
828: /* Exchange protocol version identification strings with the server. */
829: ssh_exchange_identification();
830:
831: /* Put the connection into non-blocking mode. */
832: packet_set_nonblocking();
833:
834: /* key exchange */
835: /* authenticate user */
1.59 markus 836: if (compat20) {
837: ssh_kex2(host, hostaddr);
1.120 markus 838: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 839: } else {
840: ssh_kex(host, hostaddr);
1.120 markus 841: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 842: }
1.97 markus 843: }
844:
845: void
846: ssh_put_password(char *password)
847: {
848: int size;
849: char *padded;
850:
1.99 deraadt 851: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 852: packet_put_cstring(password);
1.99 deraadt 853: return;
854: }
1.97 markus 855: size = roundup(strlen(password) + 1, 32);
856: padded = xmalloc(size);
857: memset(padded, 0, size);
858: strlcpy(padded, password, size);
859: packet_put_string(padded, size);
860: memset(padded, 0, size);
861: xfree(padded);
1.1 deraadt 862: }
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