Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.163
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"
1.163 ! avsm 16: RCSID("$OpenBSD: sshconnect.c,v 1.162 2005/03/10 22:01:06 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"
1.51 markus 34:
1.140 jakob 35: #include "dns.h"
36:
1.70 markus 37: char *client_version_string = NULL;
38: char *server_version_string = NULL;
1.59 markus 39:
1.153 jakob 40: int matching_host_key_dns = 0;
1.145 jakob 41:
1.124 markus 42: /* import */
1.43 markus 43: extern Options options;
1.50 markus 44: extern char *__progname;
1.124 markus 45: extern uid_t original_real_uid;
46: extern uid_t original_effective_uid;
1.135 djm 47: extern pid_t proxy_command_pid;
1.91 markus 48:
1.132 markus 49: static int show_other_keys(const char *, Key *);
1.150 jakob 50: static void warn_changed_key(Key *);
1.132 markus 51:
1.39 deraadt 52: /*
53: * Connect to the given ssh server using a proxy command.
54: */
1.109 itojun 55: static int
1.124 markus 56: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 57: {
1.38 markus 58: Buffer command;
59: const char *cp;
60: char *command_string;
61: int pin[2], pout[2];
1.69 deraadt 62: pid_t pid;
1.49 markus 63: char strport[NI_MAXSERV];
1.38 markus 64:
65: /* Convert the port number into a string. */
1.49 markus 66: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 67:
1.135 djm 68: /*
69: * Build the final command string in the buffer by making the
70: * appropriate substitutions to the given proxy command.
71: *
1.154 djm 72: * Use "exec" to avoid "sh -c" processes on some platforms
1.135 djm 73: * (e.g. Solaris)
74: */
1.38 markus 75: buffer_init(&command);
1.135 djm 76: buffer_append(&command, "exec ", 5);
77:
1.38 markus 78: for (cp = proxy_command; *cp; cp++) {
79: if (cp[0] == '%' && cp[1] == '%') {
80: buffer_append(&command, "%", 1);
81: cp++;
82: continue;
83: }
84: if (cp[0] == '%' && cp[1] == 'h') {
85: buffer_append(&command, host, strlen(host));
86: cp++;
87: continue;
88: }
89: if (cp[0] == '%' && cp[1] == 'p') {
1.49 markus 90: buffer_append(&command, strport, strlen(strport));
1.38 markus 91: cp++;
92: continue;
93: }
94: buffer_append(&command, cp, 1);
95: }
96: buffer_append(&command, "\0", 1);
97:
98: /* Get the final command string. */
99: command_string = buffer_ptr(&command);
100:
101: /* Create pipes for communicating with the proxy. */
102: if (pipe(pin) < 0 || pipe(pout) < 0)
103: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 104: strerror(errno));
1.38 markus 105:
106: debug("Executing proxy command: %.500s", command_string);
107:
108: /* Fork and execute the proxy command. */
109: if ((pid = fork()) == 0) {
110: char *argv[10];
111:
112: /* Child. Permanently give up superuser privileges. */
1.124 markus 113: seteuid(original_real_uid);
114: setuid(original_real_uid);
1.38 markus 115:
116: /* Redirect stdin and stdout. */
117: close(pin[1]);
118: if (pin[0] != 0) {
119: if (dup2(pin[0], 0) < 0)
120: perror("dup2 stdin");
121: close(pin[0]);
122: }
123: close(pout[0]);
124: if (dup2(pout[1], 1) < 0)
125: perror("dup2 stdout");
126: /* Cannot be 1 because pin allocated two descriptors. */
127: close(pout[1]);
128:
129: /* Stderr is left as it is so that error messages get
130: printed on the user's terminal. */
1.89 markus 131: argv[0] = _PATH_BSHELL;
1.38 markus 132: argv[1] = "-c";
133: argv[2] = command_string;
134: argv[3] = NULL;
135:
136: /* Execute the proxy command. Note that we gave up any
137: extra privileges above. */
1.89 markus 138: execv(argv[0], argv);
139: perror(argv[0]);
1.38 markus 140: exit(1);
141: }
142: /* Parent. */
143: if (pid < 0)
144: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 145: else
146: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 147:
148: /* Close child side of the descriptors. */
149: close(pin[0]);
150: close(pout[1]);
151:
152: /* Free the command name. */
153: buffer_free(&command);
154:
155: /* Set the connection file descriptors. */
156: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 157:
1.110 markus 158: /* Indicate OK return */
159: return 0;
1.1 deraadt 160: }
161:
1.39 deraadt 162: /*
163: * Creates a (possibly privileged) socket for use as the ssh connection.
164: */
1.109 itojun 165: static int
1.139 markus 166: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 167: {
1.105 markus 168: int sock, gaierr;
169: struct addrinfo hints, *res;
1.1 deraadt 170:
1.40 markus 171: /*
172: * If we are running as root and want to connect to a privileged
173: * port, bind our own socket to a privileged port.
174: */
1.38 markus 175: if (privileged) {
176: int p = IPPORT_RESERVED - 1;
1.124 markus 177: PRIV_START;
1.139 markus 178: sock = rresvport_af(&p, ai->ai_family);
1.124 markus 179: PRIV_END;
1.38 markus 180: if (sock < 0)
1.139 markus 181: error("rresvport: af=%d %.100s", ai->ai_family,
182: strerror(errno));
1.55 markus 183: else
184: debug("Allocated local port %d.", p);
1.105 markus 185: return sock;
186: }
1.139 markus 187: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.105 markus 188: if (sock < 0)
189: error("socket: %.100s", strerror(errno));
190:
191: /* Bind the socket to an alternative local IP address */
192: if (options.bind_address == NULL)
193: return sock;
194:
195: memset(&hints, 0, sizeof(hints));
1.139 markus 196: hints.ai_family = ai->ai_family;
197: hints.ai_socktype = ai->ai_socktype;
198: hints.ai_protocol = ai->ai_protocol;
1.105 markus 199: hints.ai_flags = AI_PASSIVE;
200: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
201: if (gaierr) {
202: error("getaddrinfo: %s: %s", options.bind_address,
203: gai_strerror(gaierr));
204: close(sock);
205: return -1;
206: }
207: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
208: error("bind: %s: %s", options.bind_address, strerror(errno));
209: close(sock);
210: freeaddrinfo(res);
211: return -1;
1.38 markus 212: }
1.105 markus 213: freeaddrinfo(res);
1.38 markus 214: return sock;
1.1 deraadt 215: }
216:
1.141 djm 217: static int
218: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
219: socklen_t addrlen, int timeout)
220: {
221: fd_set *fdset;
222: struct timeval tv;
223: socklen_t optlen;
1.142 djm 224: int fdsetsz, optval, rc, result = -1;
1.141 djm 225:
226: if (timeout <= 0)
227: return (connect(sockfd, serv_addr, addrlen));
228:
1.156 djm 229: set_nonblock(sockfd);
1.141 djm 230: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 231: if (rc == 0) {
232: unset_nonblock(sockfd);
1.141 djm 233: return (0);
1.156 djm 234: }
1.141 djm 235: if (errno != EINPROGRESS)
236: return (-1);
237:
238: fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask);
239: fdset = (fd_set *)xmalloc(fdsetsz);
240:
1.147 markus 241: memset(fdset, 0, fdsetsz);
1.141 djm 242: FD_SET(sockfd, fdset);
243: tv.tv_sec = timeout;
244: tv.tv_usec = 0;
245:
1.162 deraadt 246: for (;;) {
1.141 djm 247: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
248: if (rc != -1 || errno != EINTR)
249: break;
250: }
251:
1.162 deraadt 252: switch (rc) {
1.141 djm 253: case 0:
254: /* Timed out */
255: errno = ETIMEDOUT;
1.142 djm 256: break;
1.141 djm 257: case -1:
258: /* Select error */
1.154 djm 259: debug("select: %s", strerror(errno));
1.142 djm 260: break;
1.141 djm 261: case 1:
262: /* Completed or failed */
263: optval = 0;
264: optlen = sizeof(optval);
1.154 djm 265: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 266: &optlen) == -1) {
1.154 djm 267: debug("getsockopt: %s", strerror(errno));
1.142 djm 268: break;
1.148 markus 269: }
1.141 djm 270: if (optval != 0) {
271: errno = optval;
1.142 djm 272: break;
1.141 djm 273: }
1.142 djm 274: result = 0;
1.156 djm 275: unset_nonblock(sockfd);
1.141 djm 276: break;
277: default:
278: /* Should not occur */
279: fatal("Bogus return (%d) from select()", rc);
280: }
281:
1.142 djm 282: xfree(fdset);
283: return (result);
1.141 djm 284: }
285:
1.39 deraadt 286: /*
1.49 markus 287: * Opens a TCP/IP connection to the remote server on the given host.
288: * The address of the remote host will be returned in hostaddr.
1.124 markus 289: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 290: * a privileged port will be allocated to make the connection.
1.124 markus 291: * This requires super-user privileges if needpriv is true.
1.39 deraadt 292: * Connection_attempts specifies the maximum number of tries (one per
293: * second). If proxy_command is non-NULL, it specifies the command (with %h
294: * and %p substituted for host and port, respectively) to use to contact
295: * the daemon.
296: */
1.38 markus 297: int
1.49 markus 298: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 299: u_short port, int family, int connection_attempts,
1.124 markus 300: int needpriv, const char *proxy_command)
1.1 deraadt 301: {
1.90 markus 302: int gaierr;
303: int on = 1;
1.49 markus 304: int sock = -1, attempt;
1.90 markus 305: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 306: struct addrinfo hints, *ai, *aitop;
1.90 markus 307: struct servent *sp;
1.38 markus 308:
1.136 markus 309: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 310:
311: /* Get default port if port has not been set. */
312: if (port == 0) {
313: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
314: if (sp)
315: port = ntohs(sp->s_port);
316: else
317: port = SSH_DEFAULT_PORT;
318: }
319: /* If a proxy command is given, connect using it. */
320: if (proxy_command != NULL)
1.124 markus 321: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 322:
323: /* No proxy command. */
324:
1.49 markus 325: memset(&hints, 0, sizeof(hints));
1.115 markus 326: hints.ai_family = family;
1.49 markus 327: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 328: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 329: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 330: fatal("%s: %.100s: %s", __progname, host,
331: gai_strerror(gaierr));
1.38 markus 332:
1.46 markus 333: /*
334: * Try to connect several times. On some machines, the first time
335: * will sometimes fail. In general socket code appears to behave
336: * quite magically on many machines.
1.110 markus 337: */
338: for (attempt = 0; ;) {
1.38 markus 339: if (attempt > 0)
340: debug("Trying again...");
341:
1.49 markus 342: /* Loop through addresses for this host, and try each one in
1.68 markus 343: sequence until the connection succeeds. */
1.49 markus 344: for (ai = aitop; ai; ai = ai->ai_next) {
345: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
346: continue;
347: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
348: ntop, sizeof(ntop), strport, sizeof(strport),
349: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
350: error("ssh_connect: getnameinfo failed");
351: continue;
352: }
353: debug("Connecting to %.200s [%.100s] port %s.",
354: host, ntop, strport);
355:
356: /* Create a socket for connecting. */
1.139 markus 357: sock = ssh_create_socket(needpriv, ai);
1.49 markus 358: if (sock < 0)
1.110 markus 359: /* Any error is already output */
1.49 markus 360: continue;
361:
1.141 djm 362: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
363: options.connection_timeout) >= 0) {
1.49 markus 364: /* Successful connection. */
1.102 markus 365: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 366: break;
1.49 markus 367: } else {
1.131 itojun 368: debug("connect to address %s port %s: %s",
369: ntop, strport, strerror(errno));
1.40 markus 370: /*
371: * Close the failed socket; there appear to
372: * be some problems when reusing a socket for
373: * which connect() has already returned an
374: * error.
375: */
1.38 markus 376: close(sock);
377: }
378: }
1.49 markus 379: if (ai)
380: break; /* Successful connection. */
1.1 deraadt 381:
1.110 markus 382: attempt++;
383: if (attempt >= connection_attempts)
384: break;
1.38 markus 385: /* Sleep a moment before retrying. */
386: sleep(1);
387: }
1.49 markus 388:
389: freeaddrinfo(aitop);
390:
1.38 markus 391: /* Return failure if we didn't get a successful connection. */
1.130 itojun 392: if (attempt >= connection_attempts) {
1.159 markus 393: error("ssh: connect to host %s port %s: %s",
1.130 itojun 394: host, strport, strerror(errno));
1.159 markus 395: return (-1);
1.130 itojun 396: }
1.38 markus 397:
398: debug("Connection established.");
1.90 markus 399:
1.155 markus 400: /* Set SO_KEEPALIVE if requested. */
401: if (options.tcp_keep_alive &&
1.90 markus 402: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
403: sizeof(on)) < 0)
404: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 405:
406: /* Set the connection. */
407: packet_set_connection(sock, sock);
1.1 deraadt 408:
1.110 markus 409: return 0;
1.59 markus 410: }
411:
1.43 markus 412: /*
1.39 deraadt 413: * Waits for the server identification string, and sends our own
414: * identification string.
415: */
1.109 itojun 416: static void
1.95 itojun 417: ssh_exchange_identification(void)
1.1 deraadt 418: {
1.38 markus 419: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 420: int remote_major, remote_minor, i, mismatch;
1.38 markus 421: int connection_in = packet_get_connection_in();
422: int connection_out = packet_get_connection_out();
1.93 stevesk 423: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 424:
1.163 ! avsm 425: /* Read other side's version identification. */
1.75 markus 426: for (;;) {
427: for (i = 0; i < sizeof(buf) - 1; i++) {
1.163 ! avsm 428: size_t len = atomicio(read, connection_in, &buf[i], 1);
! 429:
! 430: if (len != 1 && errno == EPIPE)
! 431: fatal("ssh_exchange_identification: Connection closed by remote host");
! 432: else if (len != 1)
1.75 markus 433: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
434: if (buf[i] == '\r') {
435: buf[i] = '\n';
436: buf[i + 1] = 0;
437: continue; /**XXX wait for \n */
438: }
439: if (buf[i] == '\n') {
440: buf[i + 1] = 0;
441: break;
442: }
1.38 markus 443: }
1.75 markus 444: buf[sizeof(buf) - 1] = 0;
1.76 markus 445: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 446: break;
1.75 markus 447: debug("ssh_exchange_identification: %s", buf);
1.38 markus 448: }
1.59 markus 449: server_version_string = xstrdup(buf);
1.38 markus 450:
1.40 markus 451: /*
452: * Check that the versions match. In future this might accept
453: * several versions and set appropriate flags to handle them.
454: */
1.59 markus 455: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
456: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 457: fatal("Bad remote protocol version identification: '%.100s'", buf);
458: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 459: remote_major, remote_minor, remote_version);
1.38 markus 460:
1.59 markus 461: compat_datafellows(remote_version);
1.64 markus 462: mismatch = 0;
1.59 markus 463:
1.116 deraadt 464: switch (remote_major) {
1.64 markus 465: case 1:
466: if (remote_minor == 99 &&
467: (options.protocol & SSH_PROTO_2) &&
468: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
469: enable_compat20();
470: break;
471: }
472: if (!(options.protocol & SSH_PROTO_1)) {
473: mismatch = 1;
474: break;
475: }
476: if (remote_minor < 3) {
477: fatal("Remote machine has too old SSH software version.");
1.81 markus 478: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 479: /* We speak 1.3, too. */
480: enable_compat13();
1.81 markus 481: minor1 = 3;
1.64 markus 482: if (options.forward_agent) {
1.138 itojun 483: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 484: options.forward_agent = 0;
485: }
486: }
487: break;
488: case 2:
489: if (options.protocol & SSH_PROTO_2) {
490: enable_compat20();
491: break;
1.38 markus 492: }
1.64 markus 493: /* FALLTHROUGH */
1.68 markus 494: default:
1.64 markus 495: mismatch = 1;
496: break;
1.38 markus 497: }
1.64 markus 498: if (mismatch)
1.38 markus 499: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 500: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
501: remote_major);
1.38 markus 502: /* Send our own protocol version identification. */
503: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 504: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 505: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 506: SSH_VERSION);
1.146 deraadt 507: if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 508: fatal("write: %.100s", strerror(errno));
1.59 markus 509: client_version_string = xstrdup(buf);
510: chop(client_version_string);
511: chop(server_version_string);
512: debug("Local version string %.100s", client_version_string);
1.1 deraadt 513: }
514:
1.96 markus 515: /* defaults to 'no' */
1.109 itojun 516: static int
1.112 markus 517: confirm(const char *prompt)
1.1 deraadt 518: {
1.119 markus 519: const char *msg, *again = "Please type 'yes' or 'no': ";
520: char *p;
521: int ret = -1;
1.96 markus 522:
523: if (options.batch_mode)
524: return 0;
1.119 markus 525: for (msg = prompt;;msg = again) {
526: p = read_passphrase(msg, RP_ECHO);
527: if (p == NULL ||
528: (p[0] == '\0') || (p[0] == '\n') ||
529: strncasecmp(p, "no", 2) == 0)
530: ret = 0;
1.127 markus 531: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 532: ret = 1;
533: if (p)
534: xfree(p);
535: if (ret != -1)
536: return ret;
1.1 deraadt 537: }
538: }
539:
1.39 deraadt 540: /*
1.108 markus 541: * check whether the supplied host key is valid, return -1 if the key
542: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 543: */
1.109 itojun 544: static int
1.70 markus 545: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 546: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 547: {
1.58 markus 548: Key *file_key;
1.152 jakob 549: const char *type = key_type(host_key);
1.46 markus 550: char *ip = NULL;
1.100 markus 551: char hostline[1000], *hostp, *fp;
1.38 markus 552: HostStatus host_status;
553: HostStatus ip_status;
1.161 djm 554: int r, local = 0, host_ip_differ = 0;
1.49 markus 555: char ntop[NI_MAXHOST];
1.119 markus 556: char msg[1024];
1.145 jakob 557: int len, host_line, ip_line;
1.85 markus 558: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 559:
560: /*
561: * Force accepting of the host key for loopback/localhost. The
562: * problem is that if the home directory is NFS-mounted to multiple
563: * machines, localhost will refer to a different machine in each of
564: * them, and the user will get bogus HOST_CHANGED warnings. This
565: * essentially disables host authentication for localhost; however,
566: * this is probably not a real problem.
567: */
1.70 markus 568: /** hostaddr == 0! */
1.49 markus 569: switch (hostaddr->sa_family) {
570: case AF_INET:
1.108 markus 571: local = (ntohl(((struct sockaddr_in *)hostaddr)->
572: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 573: break;
574: case AF_INET6:
1.108 markus 575: local = IN6_IS_ADDR_LOOPBACK(
576: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 577: break;
578: default:
579: local = 0;
580: break;
581: }
1.111 markus 582: if (options.no_host_authentication_for_localhost == 1 && local &&
583: options.host_key_alias == NULL) {
1.88 markus 584: debug("Forcing accepting of host key for "
585: "loopback/localhost.");
1.108 markus 586: return 0;
1.49 markus 587: }
1.42 markus 588:
589: /*
1.88 markus 590: * We don't have the remote ip-address for connections
591: * using a proxy command
1.42 markus 592: */
1.84 markus 593: if (options.proxy_command == NULL) {
594: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 595: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 596: fatal("check_host_key: getnameinfo failed");
597: ip = xstrdup(ntop);
598: } else {
599: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 600: }
1.88 markus 601: /*
602: * Turn off check_host_ip if the connection is to localhost, via proxy
603: * command or if we don't have a hostname to compare with
604: */
605: if (options.check_host_ip &&
606: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
607: options.check_host_ip = 0;
1.86 markus 608:
609: /*
610: * Allow the user to record the key under a different name. This is
611: * useful for ssh tunneling over forwarded connections or if you run
612: * multiple sshd's on different ports on the same machine.
613: */
614: if (options.host_key_alias != NULL) {
615: host = options.host_key_alias;
616: debug("using hostkeyalias: %s", host);
1.84 markus 617: }
1.38 markus 618:
1.46 markus 619: /*
620: * Store the host key from the known host file in here so that we can
621: * compare it with the key for the IP address.
622: */
1.58 markus 623: file_key = key_new(host_key->type);
1.38 markus 624:
1.40 markus 625: /*
626: * Check if the host key is present in the user\'s list of known
627: * hosts or in the systemwide list.
628: */
1.85 markus 629: host_file = user_hostfile;
1.108 markus 630: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 631: file_key, &host_line);
1.85 markus 632: if (host_status == HOST_NEW) {
633: host_file = system_hostfile;
1.108 markus 634: host_status = check_host_in_hostfile(host_file, host, host_key,
635: file_key, &host_line);
1.85 markus 636: }
1.40 markus 637: /*
638: * Also perform check for the ip address, skip the check if we are
639: * localhost or the hostname was an ip address to begin with
640: */
1.88 markus 641: if (options.check_host_ip) {
1.58 markus 642: Key *ip_key = key_new(host_key->type);
1.38 markus 643:
1.85 markus 644: ip_file = user_hostfile;
1.108 markus 645: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
646: ip_key, &ip_line);
1.85 markus 647: if (ip_status == HOST_NEW) {
648: ip_file = system_hostfile;
1.108 markus 649: ip_status = check_host_in_hostfile(ip_file, ip,
650: host_key, ip_key, &ip_line);
1.85 markus 651: }
1.38 markus 652: if (host_status == HOST_CHANGED &&
1.58 markus 653: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 654: host_ip_differ = 1;
655:
1.58 markus 656: key_free(ip_key);
1.38 markus 657: } else
658: ip_status = host_status;
659:
1.58 markus 660: key_free(file_key);
1.38 markus 661:
662: switch (host_status) {
663: case HOST_OK:
664: /* The host is known and the key matches. */
1.72 markus 665: debug("Host '%.200s' is known and matches the %s host key.",
666: host, type);
1.85 markus 667: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 668: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 669: if (readonly)
1.138 itojun 670: logit("%s host key for IP address "
1.108 markus 671: "'%.128s' not in list of known hosts.",
672: type, ip);
673: else if (!add_host_to_hostfile(user_hostfile, ip,
1.160 djm 674: host_key, options.hash_known_hosts))
1.138 itojun 675: logit("Failed to add the %s host key for IP "
1.108 markus 676: "address '%.128s' to the list of known "
677: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 678: else
1.138 itojun 679: logit("Warning: Permanently added the %s host "
1.108 markus 680: "key for IP address '%.128s' to the list "
681: "of known hosts.", type, ip);
1.38 markus 682: }
683: break;
684: case HOST_NEW:
1.108 markus 685: if (readonly)
686: goto fail;
1.38 markus 687: /* The host is new. */
688: if (options.strict_host_key_checking == 1) {
1.108 markus 689: /*
690: * User has requested strict host key checking. We
691: * will not add the host key automatically. The only
692: * alternative left is to abort.
693: */
694: error("No %s host key is known for %.200s and you "
695: "have requested strict checking.", type, host);
696: goto fail;
1.38 markus 697: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 698: char msg1[1024], msg2[1024];
699:
700: if (show_other_keys(host, host_key))
701: snprintf(msg1, sizeof(msg1),
702: "\nbut keys of different type are already"
703: " known for this host.");
704: else
705: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 706: /* The default */
1.100 markus 707: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.145 jakob 708: msg2[0] = '\0';
709: if (options.verify_host_key_dns) {
1.153 jakob 710: if (matching_host_key_dns)
1.145 jakob 711: snprintf(msg2, sizeof(msg2),
712: "Matching host key fingerprint"
713: " found in DNS.\n");
714: else
715: snprintf(msg2, sizeof(msg2),
716: "No matching host key fingerprint"
717: " found in DNS.\n");
718: }
1.119 markus 719: snprintf(msg, sizeof(msg),
1.108 markus 720: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 721: "established%s\n"
1.145 jakob 722: "%s key fingerprint is %s.\n%s"
1.108 markus 723: "Are you sure you want to continue connecting "
1.132 markus 724: "(yes/no)? ",
1.145 jakob 725: host, ip, msg1, type, fp, msg2);
1.100 markus 726: xfree(fp);
1.119 markus 727: if (!confirm(msg))
1.108 markus 728: goto fail;
1.38 markus 729: }
1.161 djm 730: /*
731: * If not in strict mode, add the key automatically to the
732: * local known_hosts file.
733: */
1.88 markus 734: if (options.check_host_ip && ip_status == HOST_NEW) {
1.161 djm 735: snprintf(hostline, sizeof(hostline), "%s,%s",
736: host, ip);
1.38 markus 737: hostp = hostline;
1.161 djm 738: if (options.hash_known_hosts) {
739: /* Add hash of host and IP separately */
740: r = add_host_to_hostfile(user_hostfile, host,
741: host_key, options.hash_known_hosts) &&
742: add_host_to_hostfile(user_hostfile, ip,
743: host_key, options.hash_known_hosts);
744: } else {
745: /* Add unhashed "host,ip" */
746: r = add_host_to_hostfile(user_hostfile,
747: hostline, host_key,
748: options.hash_known_hosts);
749: }
750: } else {
751: r = add_host_to_hostfile(user_hostfile, host, host_key,
752: options.hash_known_hosts);
1.38 markus 753: hostp = host;
1.161 djm 754: }
1.38 markus 755:
1.161 djm 756: if (!r)
1.138 itojun 757: logit("Failed to add the host to the list of known "
1.108 markus 758: "hosts (%.500s).", user_hostfile);
1.38 markus 759: else
1.138 itojun 760: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 761: "list of known hosts.", hostp, type);
1.38 markus 762: break;
763: case HOST_CHANGED:
764: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 765: char *key_msg;
1.38 markus 766: if (ip_status == HOST_NEW)
1.158 avsm 767: key_msg = "is unknown";
1.38 markus 768: else if (ip_status == HOST_OK)
1.158 avsm 769: key_msg = "is unchanged";
1.38 markus 770: else
1.158 avsm 771: key_msg = "has a different value";
1.38 markus 772: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
773: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
774: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 775: error("The %s host key for %s has changed,", type, host);
1.38 markus 776: error("and the key for the according IP address %s", ip);
1.158 avsm 777: error("%s. This could either mean that", key_msg);
1.38 markus 778: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 779: error("and its host key have changed at the same time.");
1.88 markus 780: if (ip_status != HOST_NEW)
1.85 markus 781: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 782: }
783: /* The host key has changed. */
1.150 jakob 784: warn_changed_key(host_key);
1.38 markus 785: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 786: user_hostfile);
1.85 markus 787: error("Offending key in %s:%d", host_file, host_line);
1.38 markus 788:
1.40 markus 789: /*
790: * If strict host key checking is in use, the user will have
791: * to edit the key manually and we can only abort.
792: */
1.108 markus 793: if (options.strict_host_key_checking) {
794: error("%s host key for %.200s has changed and you have "
795: "requested strict checking.", type, host);
796: goto fail;
797: }
1.38 markus 798:
1.40 markus 799: /*
800: * If strict host key checking has not been requested, allow
1.144 djm 801: * the connection but without MITM-able authentication or
1.40 markus 802: * agent forwarding.
803: */
1.38 markus 804: if (options.password_authentication) {
1.108 markus 805: error("Password authentication is disabled to avoid "
806: "man-in-the-middle attacks.");
1.38 markus 807: options.password_authentication = 0;
1.144 djm 808: }
809: if (options.kbd_interactive_authentication) {
810: error("Keyboard-interactive authentication is disabled"
811: " to avoid man-in-the-middle attacks.");
812: options.kbd_interactive_authentication = 0;
813: options.challenge_response_authentication = 0;
814: }
815: if (options.challenge_response_authentication) {
816: error("Challenge/response authentication is disabled"
817: " to avoid man-in-the-middle attacks.");
818: options.challenge_response_authentication = 0;
1.38 markus 819: }
820: if (options.forward_agent) {
1.108 markus 821: error("Agent forwarding is disabled to avoid "
822: "man-in-the-middle attacks.");
1.38 markus 823: options.forward_agent = 0;
1.83 markus 824: }
825: if (options.forward_x11) {
1.108 markus 826: error("X11 forwarding is disabled to avoid "
827: "man-in-the-middle attacks.");
1.83 markus 828: options.forward_x11 = 0;
829: }
1.108 markus 830: if (options.num_local_forwards > 0 ||
831: options.num_remote_forwards > 0) {
832: error("Port forwarding is disabled to avoid "
833: "man-in-the-middle attacks.");
834: options.num_local_forwards =
1.118 deraadt 835: options.num_remote_forwards = 0;
1.38 markus 836: }
1.40 markus 837: /*
838: * XXX Should permit the user to change to use the new id.
839: * This could be done by converting the host key to an
840: * identifying sentence, tell that the host identifies itself
841: * by that sentence, and ask the user if he/she whishes to
842: * accept the authentication.
843: */
1.38 markus 844: break;
1.132 markus 845: case HOST_FOUND:
846: fatal("internal error");
847: break;
1.88 markus 848: }
849:
850: if (options.check_host_ip && host_status != HOST_CHANGED &&
851: ip_status == HOST_CHANGED) {
1.119 markus 852: snprintf(msg, sizeof(msg),
853: "Warning: the %s host key for '%.200s' "
854: "differs from the key for the IP address '%.128s'"
855: "\nOffending key for IP in %s:%d",
856: type, host, ip, ip_file, ip_line);
857: if (host_status == HOST_OK) {
858: len = strlen(msg);
859: snprintf(msg + len, sizeof(msg) - len,
860: "\nMatching host key in %s:%d",
1.125 deraadt 861: host_file, host_line);
1.119 markus 862: }
1.88 markus 863: if (options.strict_host_key_checking == 1) {
1.143 djm 864: logit("%s", msg);
1.108 markus 865: error("Exiting, you have requested strict checking.");
866: goto fail;
1.88 markus 867: } else if (options.strict_host_key_checking == 2) {
1.119 markus 868: strlcat(msg, "\nAre you sure you want "
869: "to continue connecting (yes/no)? ", sizeof(msg));
870: if (!confirm(msg))
1.108 markus 871: goto fail;
1.119 markus 872: } else {
1.143 djm 873: logit("%s", msg);
1.88 markus 874: }
1.38 markus 875: }
1.82 provos 876:
877: xfree(ip);
1.108 markus 878: return 0;
879:
880: fail:
881: xfree(ip);
882: return -1;
883: }
884:
1.140 jakob 885: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 886: int
887: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
888: {
889: struct stat st;
1.153 jakob 890: int flags = 0;
1.140 jakob 891:
1.153 jakob 892: if (options.verify_host_key_dns &&
893: verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
894:
895: if (flags & DNS_VERIFY_FOUND) {
896:
897: if (options.verify_host_key_dns == 1 &&
898: flags & DNS_VERIFY_MATCH &&
899: flags & DNS_VERIFY_SECURE)
900: return 0;
901:
902: if (flags & DNS_VERIFY_MATCH) {
903: matching_host_key_dns = 1;
904: } else {
905: warn_changed_key(host_key);
906: error("Update the SSHFP RR in DNS with the new "
907: "host key to get rid of this message.");
908: }
1.140 jakob 909: }
910: }
1.108 markus 911:
912: /* return ok if the key can be found in an old keyfile */
913: if (stat(options.system_hostfile2, &st) == 0 ||
914: stat(options.user_hostfile2, &st) == 0) {
915: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
916: options.user_hostfile2, options.system_hostfile2) == 0)
917: return 0;
918: }
919: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
920: options.user_hostfile, options.system_hostfile);
1.51 markus 921: }
1.70 markus 922:
1.51 markus 923: /*
924: * Starts a dialog with the server, and authenticates the current user on the
925: * server. This does not need any extra privileges. The basic connection
926: * to the server must already have been established before this is called.
927: * If login fails, this function prints an error and never returns.
928: * This function does not require super-user privileges.
929: */
930: void
1.120 markus 931: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 932: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 933: {
934: char *host, *cp;
1.70 markus 935: char *server_user, *local_user;
936:
937: local_user = xstrdup(pw->pw_name);
938: server_user = options.user ? options.user : local_user;
1.51 markus 939:
940: /* Convert the user-supplied hostname into all lowercase. */
941: host = xstrdup(orighost);
942: for (cp = host; *cp; cp++)
943: if (isupper(*cp))
944: *cp = tolower(*cp);
945:
946: /* Exchange protocol version identification strings with the server. */
947: ssh_exchange_identification();
948:
949: /* Put the connection into non-blocking mode. */
950: packet_set_nonblocking();
951:
952: /* key exchange */
953: /* authenticate user */
1.59 markus 954: if (compat20) {
955: ssh_kex2(host, hostaddr);
1.120 markus 956: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 957: } else {
958: ssh_kex(host, hostaddr);
1.120 markus 959: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 960: }
1.97 markus 961: }
962:
963: void
964: ssh_put_password(char *password)
965: {
966: int size;
967: char *padded;
968:
1.99 deraadt 969: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 970: packet_put_cstring(password);
1.99 deraadt 971: return;
972: }
1.97 markus 973: size = roundup(strlen(password) + 1, 32);
974: padded = xmalloc(size);
975: memset(padded, 0, size);
976: strlcpy(padded, password, size);
977: packet_put_string(padded, size);
978: memset(padded, 0, size);
979: xfree(padded);
1.132 markus 980: }
981:
982: static int
983: show_key_from_file(const char *file, const char *host, int keytype)
984: {
985: Key *found;
986: char *fp;
987: int line, ret;
988:
989: found = key_new(keytype);
990: if ((ret = lookup_key_in_hostfile_by_type(file, host,
991: keytype, found, &line))) {
992: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 993: logit("WARNING: %s key found for host %s\n"
1.133 markus 994: "in %s:%d\n"
1.132 markus 995: "%s key fingerprint %s.",
996: key_type(found), host, file, line,
997: key_type(found), fp);
998: xfree(fp);
999: }
1000: key_free(found);
1001: return (ret);
1002: }
1003:
1004: /* print all known host keys for a given host, but skip keys of given type */
1005: static int
1006: show_other_keys(const char *host, Key *key)
1007: {
1008: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
1009: int i, found = 0;
1010:
1011: for (i = 0; type[i] != -1; i++) {
1012: if (type[i] == key->type)
1013: continue;
1014: if (type[i] != KEY_RSA1 &&
1015: show_key_from_file(options.user_hostfile2, host, type[i])) {
1016: found = 1;
1017: continue;
1018: }
1019: if (type[i] != KEY_RSA1 &&
1020: show_key_from_file(options.system_hostfile2, host, type[i])) {
1021: found = 1;
1022: continue;
1023: }
1024: if (show_key_from_file(options.user_hostfile, host, type[i])) {
1025: found = 1;
1026: continue;
1027: }
1028: if (show_key_from_file(options.system_hostfile, host, type[i])) {
1029: found = 1;
1030: continue;
1031: }
1032: debug2("no key of type %d for host %s", type[i], host);
1033: }
1034: return (found);
1.150 jakob 1035: }
1036:
1037: static void
1038: warn_changed_key(Key *host_key)
1039: {
1040: char *fp;
1.151 jakob 1041: const char *type = key_type(host_key);
1.150 jakob 1042:
1043: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1044:
1045: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1046: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1047: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1048: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1049: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1050: error("It is also possible that the %s host key has just been changed.", type);
1051: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1052: type, fp);
1053: error("Please contact your system administrator.");
1054:
1055: xfree(fp);
1.1 deraadt 1056: }
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