Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.134
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"
1.134 ! stevesk 16: RCSID("$OpenBSD: sshconnect.c,v 1.133 2002/07/29 18:57:30 markus Exp $");
1.1 deraadt 17:
1.66 markus 18: #include <openssl/bn.h>
1.71 markus 19:
1.91 markus 20: #include "ssh.h"
1.1 deraadt 21: #include "xmalloc.h"
22: #include "rsa.h"
1.59 markus 23: #include "buffer.h"
1.1 deraadt 24: #include "packet.h"
25: #include "uidswap.h"
1.21 markus 26: #include "compat.h"
1.58 markus 27: #include "key.h"
1.71 markus 28: #include "sshconnect.h"
1.58 markus 29: #include "hostfile.h"
1.91 markus 30: #include "log.h"
31: #include "readconf.h"
32: #include "atomicio.h"
33: #include "misc.h"
1.119 markus 34: #include "readpass.h"
1.51 markus 35:
1.70 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:
1.132 markus 45: static int show_other_keys(const char *, Key *);
46:
1.39 deraadt 47: /*
48: * Connect to the given ssh server using a proxy command.
49: */
1.109 itojun 50: static int
1.124 markus 51: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 52: {
1.38 markus 53: Buffer command;
54: const char *cp;
55: char *command_string;
56: int pin[2], pout[2];
1.69 deraadt 57: pid_t pid;
1.49 markus 58: char strport[NI_MAXSERV];
1.38 markus 59:
60: /* Convert the port number into a string. */
1.49 markus 61: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 62:
63: /* Build the final command string in the buffer by making the
64: appropriate substitutions to the given proxy command. */
65: buffer_init(&command);
66: for (cp = proxy_command; *cp; cp++) {
67: if (cp[0] == '%' && cp[1] == '%') {
68: buffer_append(&command, "%", 1);
69: cp++;
70: continue;
71: }
72: if (cp[0] == '%' && cp[1] == 'h') {
73: buffer_append(&command, host, strlen(host));
74: cp++;
75: continue;
76: }
77: if (cp[0] == '%' && cp[1] == 'p') {
1.49 markus 78: buffer_append(&command, strport, strlen(strport));
1.38 markus 79: cp++;
80: continue;
81: }
82: buffer_append(&command, cp, 1);
83: }
84: buffer_append(&command, "\0", 1);
85:
86: /* Get the final command string. */
87: command_string = buffer_ptr(&command);
88:
89: /* Create pipes for communicating with the proxy. */
90: if (pipe(pin) < 0 || pipe(pout) < 0)
91: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 92: strerror(errno));
1.38 markus 93:
94: debug("Executing proxy command: %.500s", command_string);
95:
96: /* Fork and execute the proxy command. */
97: if ((pid = fork()) == 0) {
98: char *argv[10];
99:
100: /* Child. Permanently give up superuser privileges. */
1.124 markus 101: seteuid(original_real_uid);
102: setuid(original_real_uid);
1.38 markus 103:
104: /* Redirect stdin and stdout. */
105: close(pin[1]);
106: if (pin[0] != 0) {
107: if (dup2(pin[0], 0) < 0)
108: perror("dup2 stdin");
109: close(pin[0]);
110: }
111: close(pout[0]);
112: if (dup2(pout[1], 1) < 0)
113: perror("dup2 stdout");
114: /* Cannot be 1 because pin allocated two descriptors. */
115: close(pout[1]);
116:
117: /* Stderr is left as it is so that error messages get
118: printed on the user's terminal. */
1.89 markus 119: argv[0] = _PATH_BSHELL;
1.38 markus 120: argv[1] = "-c";
121: argv[2] = command_string;
122: argv[3] = NULL;
123:
124: /* Execute the proxy command. Note that we gave up any
125: extra privileges above. */
1.89 markus 126: execv(argv[0], argv);
127: perror(argv[0]);
1.38 markus 128: exit(1);
129: }
130: /* Parent. */
131: if (pid < 0)
132: fatal("fork failed: %.100s", strerror(errno));
133:
134: /* Close child side of the descriptors. */
135: close(pin[0]);
136: close(pout[1]);
137:
138: /* Free the command name. */
139: buffer_free(&command);
140:
141: /* Set the connection file descriptors. */
142: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 143:
1.110 markus 144: /* Indicate OK return */
145: return 0;
1.1 deraadt 146: }
147:
1.39 deraadt 148: /*
149: * Creates a (possibly privileged) socket for use as the ssh connection.
150: */
1.109 itojun 151: static int
1.124 markus 152: ssh_create_socket(int privileged, int family)
1.1 deraadt 153: {
1.105 markus 154: int sock, gaierr;
155: struct addrinfo hints, *res;
1.1 deraadt 156:
1.40 markus 157: /*
158: * If we are running as root and want to connect to a privileged
159: * port, bind our own socket to a privileged port.
160: */
1.38 markus 161: if (privileged) {
162: int p = IPPORT_RESERVED - 1;
1.124 markus 163: PRIV_START;
1.49 markus 164: sock = rresvport_af(&p, family);
1.124 markus 165: PRIV_END;
1.38 markus 166: if (sock < 0)
1.55 markus 167: error("rresvport: af=%d %.100s", family, strerror(errno));
168: else
169: debug("Allocated local port %d.", p);
1.105 markus 170: return sock;
171: }
172: sock = socket(family, SOCK_STREAM, 0);
173: if (sock < 0)
174: error("socket: %.100s", strerror(errno));
175:
176: /* Bind the socket to an alternative local IP address */
177: if (options.bind_address == NULL)
178: return sock;
179:
180: memset(&hints, 0, sizeof(hints));
1.114 markus 181: hints.ai_family = family;
1.105 markus 182: hints.ai_socktype = SOCK_STREAM;
183: hints.ai_flags = AI_PASSIVE;
184: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
185: if (gaierr) {
186: error("getaddrinfo: %s: %s", options.bind_address,
187: gai_strerror(gaierr));
188: close(sock);
189: return -1;
190: }
191: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
192: error("bind: %s: %s", options.bind_address, strerror(errno));
193: close(sock);
194: freeaddrinfo(res);
195: return -1;
1.38 markus 196: }
1.105 markus 197: freeaddrinfo(res);
1.38 markus 198: return sock;
1.1 deraadt 199: }
200:
1.39 deraadt 201: /*
1.49 markus 202: * Opens a TCP/IP connection to the remote server on the given host.
203: * The address of the remote host will be returned in hostaddr.
1.124 markus 204: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 205: * a privileged port will be allocated to make the connection.
1.124 markus 206: * This requires super-user privileges if needpriv is true.
1.39 deraadt 207: * Connection_attempts specifies the maximum number of tries (one per
208: * second). If proxy_command is non-NULL, it specifies the command (with %h
209: * and %p substituted for host and port, respectively) to use to contact
210: * the daemon.
1.110 markus 211: * Return values:
212: * 0 for OK
213: * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
214: * ECONNABORTED if we failed without a "Connection refused"
215: * Suitable error messages for the connection failure will already have been
216: * printed.
1.39 deraadt 217: */
1.38 markus 218: int
1.49 markus 219: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 220: u_short port, int family, int connection_attempts,
1.124 markus 221: int needpriv, const char *proxy_command)
1.1 deraadt 222: {
1.90 markus 223: int gaierr;
224: int on = 1;
1.49 markus 225: int sock = -1, attempt;
1.90 markus 226: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 227: struct addrinfo hints, *ai, *aitop;
1.90 markus 228: struct servent *sp;
1.110 markus 229: /*
230: * Did we get only other errors than "Connection refused" (which
231: * should block fallback to rsh and similar), or did we get at least
232: * one "Connection refused"?
233: */
234: int full_failure = 1;
1.38 markus 235:
1.124 markus 236: debug("ssh_connect: needpriv %d", needpriv);
1.38 markus 237:
238: /* Get default port if port has not been set. */
239: if (port == 0) {
240: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
241: if (sp)
242: port = ntohs(sp->s_port);
243: else
244: port = SSH_DEFAULT_PORT;
245: }
246: /* If a proxy command is given, connect using it. */
247: if (proxy_command != NULL)
1.124 markus 248: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 249:
250: /* No proxy command. */
251:
1.49 markus 252: memset(&hints, 0, sizeof(hints));
1.115 markus 253: hints.ai_family = family;
1.49 markus 254: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 255: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 256: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 257: fatal("%s: %.100s: %s", __progname, host,
258: gai_strerror(gaierr));
1.38 markus 259:
1.46 markus 260: /*
261: * Try to connect several times. On some machines, the first time
262: * will sometimes fail. In general socket code appears to behave
263: * quite magically on many machines.
1.110 markus 264: */
265: for (attempt = 0; ;) {
1.38 markus 266: if (attempt > 0)
267: debug("Trying again...");
268:
1.49 markus 269: /* Loop through addresses for this host, and try each one in
1.68 markus 270: sequence until the connection succeeds. */
1.49 markus 271: for (ai = aitop; ai; ai = ai->ai_next) {
272: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
273: continue;
274: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
275: ntop, sizeof(ntop), strport, sizeof(strport),
276: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
277: error("ssh_connect: getnameinfo failed");
278: continue;
279: }
280: debug("Connecting to %.200s [%.100s] port %s.",
281: host, ntop, strport);
282:
283: /* Create a socket for connecting. */
1.124 markus 284: sock = ssh_create_socket(needpriv, ai->ai_family);
1.49 markus 285: if (sock < 0)
1.110 markus 286: /* Any error is already output */
1.49 markus 287: continue;
288:
289: if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
290: /* Successful connection. */
1.102 markus 291: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 292: break;
1.49 markus 293: } else {
1.110 markus 294: if (errno == ECONNREFUSED)
295: full_failure = 0;
1.131 itojun 296: debug("connect to address %s port %s: %s",
297: ntop, strport, strerror(errno));
1.40 markus 298: /*
299: * Close the failed socket; there appear to
300: * be some problems when reusing a socket for
301: * which connect() has already returned an
302: * error.
303: */
1.38 markus 304: close(sock);
305: }
306: }
1.49 markus 307: if (ai)
308: break; /* Successful connection. */
1.1 deraadt 309:
1.110 markus 310: attempt++;
311: if (attempt >= connection_attempts)
312: break;
1.38 markus 313: /* Sleep a moment before retrying. */
314: sleep(1);
315: }
1.49 markus 316:
317: freeaddrinfo(aitop);
318:
1.38 markus 319: /* Return failure if we didn't get a successful connection. */
1.130 itojun 320: if (attempt >= connection_attempts) {
321: log("ssh: connect to host %s port %s: %s",
322: host, strport, strerror(errno));
1.110 markus 323: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.130 itojun 324: }
1.38 markus 325:
326: debug("Connection established.");
1.90 markus 327:
328: /* Set keepalives if requested. */
329: if (options.keepalives &&
330: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
331: sizeof(on)) < 0)
332: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 333:
334: /* Set the connection. */
335: packet_set_connection(sock, sock);
1.1 deraadt 336:
1.110 markus 337: return 0;
1.59 markus 338: }
339:
1.43 markus 340: /*
1.39 deraadt 341: * Waits for the server identification string, and sends our own
342: * identification string.
343: */
1.109 itojun 344: static void
1.95 itojun 345: ssh_exchange_identification(void)
1.1 deraadt 346: {
1.38 markus 347: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 348: int remote_major, remote_minor, i, mismatch;
1.38 markus 349: int connection_in = packet_get_connection_in();
350: int connection_out = packet_get_connection_out();
1.93 stevesk 351: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 352:
353: /* Read other side\'s version identification. */
1.75 markus 354: for (;;) {
355: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 356: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 357: if (len < 0)
358: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
359: if (len != 1)
360: fatal("ssh_exchange_identification: Connection closed by remote host");
361: if (buf[i] == '\r') {
362: buf[i] = '\n';
363: buf[i + 1] = 0;
364: continue; /**XXX wait for \n */
365: }
366: if (buf[i] == '\n') {
367: buf[i + 1] = 0;
368: break;
369: }
1.38 markus 370: }
1.75 markus 371: buf[sizeof(buf) - 1] = 0;
1.76 markus 372: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 373: break;
1.75 markus 374: debug("ssh_exchange_identification: %s", buf);
1.38 markus 375: }
1.59 markus 376: server_version_string = xstrdup(buf);
1.38 markus 377:
1.40 markus 378: /*
379: * Check that the versions match. In future this might accept
380: * several versions and set appropriate flags to handle them.
381: */
1.59 markus 382: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
383: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 384: fatal("Bad remote protocol version identification: '%.100s'", buf);
385: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 386: remote_major, remote_minor, remote_version);
1.38 markus 387:
1.59 markus 388: compat_datafellows(remote_version);
1.64 markus 389: mismatch = 0;
1.59 markus 390:
1.116 deraadt 391: switch (remote_major) {
1.64 markus 392: case 1:
393: if (remote_minor == 99 &&
394: (options.protocol & SSH_PROTO_2) &&
395: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
396: enable_compat20();
397: break;
398: }
399: if (!(options.protocol & SSH_PROTO_1)) {
400: mismatch = 1;
401: break;
402: }
403: if (remote_minor < 3) {
404: fatal("Remote machine has too old SSH software version.");
1.81 markus 405: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 406: /* We speak 1.3, too. */
407: enable_compat13();
1.81 markus 408: minor1 = 3;
1.64 markus 409: if (options.forward_agent) {
410: log("Agent forwarding disabled for protocol 1.3");
411: options.forward_agent = 0;
412: }
413: }
414: break;
415: case 2:
416: if (options.protocol & SSH_PROTO_2) {
417: enable_compat20();
418: break;
1.38 markus 419: }
1.64 markus 420: /* FALLTHROUGH */
1.68 markus 421: default:
1.64 markus 422: mismatch = 1;
423: break;
1.38 markus 424: }
1.64 markus 425: if (mismatch)
1.38 markus 426: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 427: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
428: remote_major);
1.38 markus 429: /* Send our own protocol version identification. */
430: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 431: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 432: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 433: SSH_VERSION);
1.45 deraadt 434: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 435: fatal("write: %.100s", strerror(errno));
1.59 markus 436: client_version_string = xstrdup(buf);
437: chop(client_version_string);
438: chop(server_version_string);
439: debug("Local version string %.100s", client_version_string);
1.1 deraadt 440: }
441:
1.96 markus 442: /* defaults to 'no' */
1.109 itojun 443: static int
1.112 markus 444: confirm(const char *prompt)
1.1 deraadt 445: {
1.119 markus 446: const char *msg, *again = "Please type 'yes' or 'no': ";
447: char *p;
448: int ret = -1;
1.96 markus 449:
450: if (options.batch_mode)
451: return 0;
1.119 markus 452: for (msg = prompt;;msg = again) {
453: p = read_passphrase(msg, RP_ECHO);
454: if (p == NULL ||
455: (p[0] == '\0') || (p[0] == '\n') ||
456: strncasecmp(p, "no", 2) == 0)
457: ret = 0;
1.127 markus 458: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 459: ret = 1;
460: if (p)
461: xfree(p);
462: if (ret != -1)
463: return ret;
1.1 deraadt 464: }
465: }
466:
1.39 deraadt 467: /*
1.108 markus 468: * check whether the supplied host key is valid, return -1 if the key
469: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 470: */
1.109 itojun 471: static int
1.70 markus 472: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 473: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 474: {
1.58 markus 475: Key *file_key;
1.72 markus 476: char *type = key_type(host_key);
1.46 markus 477: char *ip = NULL;
1.100 markus 478: char hostline[1000], *hostp, *fp;
1.38 markus 479: HostStatus host_status;
480: HostStatus ip_status;
1.49 markus 481: int local = 0, host_ip_differ = 0;
482: char ntop[NI_MAXHOST];
1.119 markus 483: char msg[1024];
1.132 markus 484: int len, host_line, ip_line, has_keys;
1.85 markus 485: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 486:
487: /*
488: * Force accepting of the host key for loopback/localhost. The
489: * problem is that if the home directory is NFS-mounted to multiple
490: * machines, localhost will refer to a different machine in each of
491: * them, and the user will get bogus HOST_CHANGED warnings. This
492: * essentially disables host authentication for localhost; however,
493: * this is probably not a real problem.
494: */
1.70 markus 495: /** hostaddr == 0! */
1.49 markus 496: switch (hostaddr->sa_family) {
497: case AF_INET:
1.108 markus 498: local = (ntohl(((struct sockaddr_in *)hostaddr)->
499: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 500: break;
501: case AF_INET6:
1.108 markus 502: local = IN6_IS_ADDR_LOOPBACK(
503: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 504: break;
505: default:
506: local = 0;
507: break;
508: }
1.111 markus 509: if (options.no_host_authentication_for_localhost == 1 && local &&
510: options.host_key_alias == NULL) {
1.88 markus 511: debug("Forcing accepting of host key for "
512: "loopback/localhost.");
1.108 markus 513: return 0;
1.49 markus 514: }
1.42 markus 515:
516: /*
1.88 markus 517: * We don't have the remote ip-address for connections
518: * using a proxy command
1.42 markus 519: */
1.84 markus 520: if (options.proxy_command == NULL) {
521: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 522: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 523: fatal("check_host_key: getnameinfo failed");
524: ip = xstrdup(ntop);
525: } else {
526: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 527: }
1.88 markus 528: /*
529: * Turn off check_host_ip if the connection is to localhost, via proxy
530: * command or if we don't have a hostname to compare with
531: */
532: if (options.check_host_ip &&
533: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
534: options.check_host_ip = 0;
1.86 markus 535:
536: /*
537: * Allow the user to record the key under a different name. This is
538: * useful for ssh tunneling over forwarded connections or if you run
539: * multiple sshd's on different ports on the same machine.
540: */
541: if (options.host_key_alias != NULL) {
542: host = options.host_key_alias;
543: debug("using hostkeyalias: %s", host);
1.84 markus 544: }
1.38 markus 545:
1.46 markus 546: /*
547: * Store the host key from the known host file in here so that we can
548: * compare it with the key for the IP address.
549: */
1.58 markus 550: file_key = key_new(host_key->type);
1.38 markus 551:
1.40 markus 552: /*
553: * Check if the host key is present in the user\'s list of known
554: * hosts or in the systemwide list.
555: */
1.85 markus 556: host_file = user_hostfile;
1.108 markus 557: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 558: file_key, &host_line);
1.85 markus 559: if (host_status == HOST_NEW) {
560: host_file = system_hostfile;
1.108 markus 561: host_status = check_host_in_hostfile(host_file, host, host_key,
562: file_key, &host_line);
1.85 markus 563: }
1.40 markus 564: /*
565: * Also perform check for the ip address, skip the check if we are
566: * localhost or the hostname was an ip address to begin with
567: */
1.88 markus 568: if (options.check_host_ip) {
1.58 markus 569: Key *ip_key = key_new(host_key->type);
1.38 markus 570:
1.85 markus 571: ip_file = user_hostfile;
1.108 markus 572: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
573: ip_key, &ip_line);
1.85 markus 574: if (ip_status == HOST_NEW) {
575: ip_file = system_hostfile;
1.108 markus 576: ip_status = check_host_in_hostfile(ip_file, ip,
577: host_key, ip_key, &ip_line);
1.85 markus 578: }
1.38 markus 579: if (host_status == HOST_CHANGED &&
1.58 markus 580: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 581: host_ip_differ = 1;
582:
1.58 markus 583: key_free(ip_key);
1.38 markus 584: } else
585: ip_status = host_status;
586:
1.58 markus 587: key_free(file_key);
1.38 markus 588:
589: switch (host_status) {
590: case HOST_OK:
591: /* The host is known and the key matches. */
1.72 markus 592: debug("Host '%.200s' is known and matches the %s host key.",
593: host, type);
1.85 markus 594: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 595: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 596: if (readonly)
597: log("%s host key for IP address "
598: "'%.128s' not in list of known hosts.",
599: type, ip);
600: else if (!add_host_to_hostfile(user_hostfile, ip,
1.118 deraadt 601: host_key))
1.108 markus 602: log("Failed to add the %s host key for IP "
603: "address '%.128s' to the list of known "
604: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 605: else
1.108 markus 606: log("Warning: Permanently added the %s host "
607: "key for IP address '%.128s' to the list "
608: "of known hosts.", type, ip);
1.38 markus 609: }
610: break;
611: case HOST_NEW:
1.108 markus 612: if (readonly)
613: goto fail;
1.38 markus 614: /* The host is new. */
615: if (options.strict_host_key_checking == 1) {
1.108 markus 616: /*
617: * User has requested strict host key checking. We
618: * will not add the host key automatically. The only
619: * alternative left is to abort.
620: */
621: error("No %s host key is known for %.200s and you "
622: "have requested strict checking.", type, host);
623: goto fail;
1.38 markus 624: } else if (options.strict_host_key_checking == 2) {
1.132 markus 625: has_keys = show_other_keys(host, host_key);
1.38 markus 626: /* The default */
1.100 markus 627: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.119 markus 628: snprintf(msg, sizeof(msg),
1.108 markus 629: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 630: "established%s\n"
1.72 markus 631: "%s key fingerprint is %s.\n"
1.108 markus 632: "Are you sure you want to continue connecting "
1.132 markus 633: "(yes/no)? ",
634: host, ip,
635: has_keys ? ",\nbut keys of different type are already "
636: "known for this host." : ".",
637: type, fp);
1.100 markus 638: xfree(fp);
1.119 markus 639: if (!confirm(msg))
1.108 markus 640: goto fail;
1.38 markus 641: }
1.88 markus 642: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 643: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
644: hostp = hostline;
645: } else
646: hostp = host;
647:
1.108 markus 648: /*
649: * If not in strict mode, add the key automatically to the
650: * local known_hosts file.
651: */
1.70 markus 652: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.108 markus 653: log("Failed to add the host to the list of known "
654: "hosts (%.500s).", user_hostfile);
1.38 markus 655: else
1.108 markus 656: log("Warning: Permanently added '%.200s' (%s) to the "
657: "list of known hosts.", hostp, type);
1.38 markus 658: break;
659: case HOST_CHANGED:
660: if (options.check_host_ip && host_ip_differ) {
661: char *msg;
662: if (ip_status == HOST_NEW)
663: msg = "is unknown";
664: else if (ip_status == HOST_OK)
665: msg = "is unchanged";
666: else
667: msg = "has a different value";
668: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
669: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
670: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 671: error("The %s host key for %s has changed,", type, host);
1.38 markus 672: error("and the key for the according IP address %s", ip);
673: error("%s. This could either mean that", msg);
674: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 675: error("and its host key have changed at the same time.");
1.88 markus 676: if (ip_status != HOST_NEW)
1.85 markus 677: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 678: }
679: /* The host key has changed. */
1.100 markus 680: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 681: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 682: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 683: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
684: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
685: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 686: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 687: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.100 markus 688: type, fp);
1.38 markus 689: error("Please contact your system administrator.");
690: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 691: user_hostfile);
1.85 markus 692: error("Offending key in %s:%d", host_file, host_line);
1.100 markus 693: xfree(fp);
1.38 markus 694:
1.40 markus 695: /*
696: * If strict host key checking is in use, the user will have
697: * to edit the key manually and we can only abort.
698: */
1.108 markus 699: if (options.strict_host_key_checking) {
700: error("%s host key for %.200s has changed and you have "
701: "requested strict checking.", type, host);
702: goto fail;
703: }
1.38 markus 704:
1.40 markus 705: /*
706: * If strict host key checking has not been requested, allow
707: * the connection but without password authentication or
708: * agent forwarding.
709: */
1.38 markus 710: if (options.password_authentication) {
1.108 markus 711: error("Password authentication is disabled to avoid "
712: "man-in-the-middle attacks.");
1.38 markus 713: options.password_authentication = 0;
714: }
715: if (options.forward_agent) {
1.108 markus 716: error("Agent forwarding is disabled to avoid "
717: "man-in-the-middle attacks.");
1.38 markus 718: options.forward_agent = 0;
1.83 markus 719: }
720: if (options.forward_x11) {
1.108 markus 721: error("X11 forwarding is disabled to avoid "
722: "man-in-the-middle attacks.");
1.83 markus 723: options.forward_x11 = 0;
724: }
1.108 markus 725: if (options.num_local_forwards > 0 ||
726: options.num_remote_forwards > 0) {
727: error("Port forwarding is disabled to avoid "
728: "man-in-the-middle attacks.");
729: options.num_local_forwards =
1.118 deraadt 730: options.num_remote_forwards = 0;
1.38 markus 731: }
1.40 markus 732: /*
733: * XXX Should permit the user to change to use the new id.
734: * This could be done by converting the host key to an
735: * identifying sentence, tell that the host identifies itself
736: * by that sentence, and ask the user if he/she whishes to
737: * accept the authentication.
738: */
1.38 markus 739: break;
1.132 markus 740: case HOST_FOUND:
741: fatal("internal error");
742: break;
1.88 markus 743: }
744:
745: if (options.check_host_ip && host_status != HOST_CHANGED &&
746: ip_status == HOST_CHANGED) {
1.119 markus 747: snprintf(msg, sizeof(msg),
748: "Warning: the %s host key for '%.200s' "
749: "differs from the key for the IP address '%.128s'"
750: "\nOffending key for IP in %s:%d",
751: type, host, ip, ip_file, ip_line);
752: if (host_status == HOST_OK) {
753: len = strlen(msg);
754: snprintf(msg + len, sizeof(msg) - len,
755: "\nMatching host key in %s:%d",
1.125 deraadt 756: host_file, host_line);
1.119 markus 757: }
1.88 markus 758: if (options.strict_host_key_checking == 1) {
1.119 markus 759: log(msg);
1.108 markus 760: error("Exiting, you have requested strict checking.");
761: goto fail;
1.88 markus 762: } else if (options.strict_host_key_checking == 2) {
1.119 markus 763: strlcat(msg, "\nAre you sure you want "
764: "to continue connecting (yes/no)? ", sizeof(msg));
765: if (!confirm(msg))
1.108 markus 766: goto fail;
1.119 markus 767: } else {
768: log(msg);
1.88 markus 769: }
1.38 markus 770: }
1.82 provos 771:
772: xfree(ip);
1.108 markus 773: return 0;
774:
775: fail:
776: xfree(ip);
777: return -1;
778: }
779:
780: int
781: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
782: {
783: struct stat st;
784:
785: /* return ok if the key can be found in an old keyfile */
786: if (stat(options.system_hostfile2, &st) == 0 ||
787: stat(options.user_hostfile2, &st) == 0) {
788: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
789: options.user_hostfile2, options.system_hostfile2) == 0)
790: return 0;
791: }
792: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
793: options.user_hostfile, options.system_hostfile);
1.51 markus 794: }
1.70 markus 795:
1.51 markus 796: /*
797: * Starts a dialog with the server, and authenticates the current user on the
798: * server. This does not need any extra privileges. The basic connection
799: * to the server must already have been established before this is called.
800: * If login fails, this function prints an error and never returns.
801: * This function does not require super-user privileges.
802: */
803: void
1.120 markus 804: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 805: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 806: {
807: char *host, *cp;
1.70 markus 808: char *server_user, *local_user;
809:
810: local_user = xstrdup(pw->pw_name);
811: server_user = options.user ? options.user : local_user;
1.51 markus 812:
813: /* Convert the user-supplied hostname into all lowercase. */
814: host = xstrdup(orighost);
815: for (cp = host; *cp; cp++)
816: if (isupper(*cp))
817: *cp = tolower(*cp);
818:
819: /* Exchange protocol version identification strings with the server. */
820: ssh_exchange_identification();
821:
822: /* Put the connection into non-blocking mode. */
823: packet_set_nonblocking();
824:
825: /* key exchange */
826: /* authenticate user */
1.59 markus 827: if (compat20) {
828: ssh_kex2(host, hostaddr);
1.120 markus 829: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 830: } else {
831: ssh_kex(host, hostaddr);
1.120 markus 832: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 833: }
1.97 markus 834: }
835:
836: void
837: ssh_put_password(char *password)
838: {
839: int size;
840: char *padded;
841:
1.99 deraadt 842: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 843: packet_put_cstring(password);
1.99 deraadt 844: return;
845: }
1.97 markus 846: size = roundup(strlen(password) + 1, 32);
847: padded = xmalloc(size);
848: memset(padded, 0, size);
849: strlcpy(padded, password, size);
850: packet_put_string(padded, size);
851: memset(padded, 0, size);
852: xfree(padded);
1.132 markus 853: }
854:
855: static int
856: show_key_from_file(const char *file, const char *host, int keytype)
857: {
858: Key *found;
859: char *fp;
860: int line, ret;
861:
862: found = key_new(keytype);
863: if ((ret = lookup_key_in_hostfile_by_type(file, host,
864: keytype, found, &line))) {
865: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
866: log("WARNING: %s key found for host %s\n"
1.133 markus 867: "in %s:%d\n"
1.132 markus 868: "%s key fingerprint %s.",
869: key_type(found), host, file, line,
870: key_type(found), fp);
871: xfree(fp);
872: }
873: key_free(found);
874: return (ret);
875: }
876:
877: /* print all known host keys for a given host, but skip keys of given type */
878: static int
879: show_other_keys(const char *host, Key *key)
880: {
881: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
882: int i, found = 0;
883:
884: for (i = 0; type[i] != -1; i++) {
885: if (type[i] == key->type)
886: continue;
887: if (type[i] != KEY_RSA1 &&
888: show_key_from_file(options.user_hostfile2, host, type[i])) {
889: found = 1;
890: continue;
891: }
892: if (type[i] != KEY_RSA1 &&
893: show_key_from_file(options.system_hostfile2, host, type[i])) {
894: found = 1;
895: continue;
896: }
897: if (show_key_from_file(options.user_hostfile, host, type[i])) {
898: found = 1;
899: continue;
900: }
901: if (show_key_from_file(options.system_hostfile, host, type[i])) {
902: found = 1;
903: continue;
904: }
905: debug2("no key of type %d for host %s", type[i], host);
906: }
907: return (found);
1.1 deraadt 908: }
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