Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.176
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"
1.176 ! stevesk 16: RCSID("$OpenBSD: sshconnect.c,v 1.175 2006/02/20 17:19:54 stevesk Exp $");
1.174 stevesk 17:
18: #include <sys/types.h>
19: #include <sys/wait.h>
1.175 stevesk 20: #include <sys/stat.h>
1.172 stevesk 21:
1.176 ! stevesk 22: #include <ctype.h>
1.172 stevesk 23: #include <paths.h>
1.71 markus 24:
1.91 markus 25: #include "ssh.h"
1.1 deraadt 26: #include "xmalloc.h"
27: #include "rsa.h"
1.59 markus 28: #include "buffer.h"
1.1 deraadt 29: #include "packet.h"
30: #include "uidswap.h"
1.21 markus 31: #include "compat.h"
1.58 markus 32: #include "key.h"
1.71 markus 33: #include "sshconnect.h"
1.58 markus 34: #include "hostfile.h"
1.91 markus 35: #include "log.h"
36: #include "readconf.h"
37: #include "atomicio.h"
38: #include "misc.h"
1.140 jakob 39: #include "dns.h"
40:
1.70 markus 41: char *client_version_string = NULL;
42: char *server_version_string = NULL;
1.59 markus 43:
1.169 stevesk 44: static int matching_host_key_dns = 0;
1.145 jakob 45:
1.124 markus 46: /* import */
1.43 markus 47: extern Options options;
1.50 markus 48: extern char *__progname;
1.124 markus 49: extern uid_t original_real_uid;
50: extern uid_t original_effective_uid;
1.135 djm 51: extern pid_t proxy_command_pid;
1.91 markus 52:
1.132 markus 53: static int show_other_keys(const char *, Key *);
1.150 jakob 54: static void warn_changed_key(Key *);
1.132 markus 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: {
1.164 djm 62: char *command_string, *tmp;
1.38 markus 63: int pin[2], pout[2];
1.69 deraadt 64: pid_t pid;
1.49 markus 65: char strport[NI_MAXSERV];
1.164 djm 66: size_t len;
1.38 markus 67:
68: /* Convert the port number into a string. */
1.49 markus 69: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 70:
1.135 djm 71: /*
72: * Build the final command string in the buffer by making the
73: * appropriate substitutions to the given proxy command.
74: *
1.154 djm 75: * Use "exec" to avoid "sh -c" processes on some platforms
1.135 djm 76: * (e.g. Solaris)
77: */
1.164 djm 78: len = strlen(proxy_command) + 6;
79: tmp = xmalloc(len);
80: strlcpy(tmp, "exec ", len);
81: strlcat(tmp, proxy_command, len);
82: command_string = percent_expand(tmp, "h", host,
83: "p", strport, (char *)NULL);
84: xfree(tmp);
1.38 markus 85:
86: /* Create pipes for communicating with the proxy. */
87: if (pipe(pin) < 0 || pipe(pout) < 0)
88: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 89: strerror(errno));
1.38 markus 90:
91: debug("Executing proxy command: %.500s", command_string);
92:
93: /* Fork and execute the proxy command. */
94: if ((pid = fork()) == 0) {
95: char *argv[10];
96:
97: /* Child. Permanently give up superuser privileges. */
1.124 markus 98: seteuid(original_real_uid);
99: setuid(original_real_uid);
1.38 markus 100:
101: /* Redirect stdin and stdout. */
102: close(pin[1]);
103: if (pin[0] != 0) {
104: if (dup2(pin[0], 0) < 0)
105: perror("dup2 stdin");
106: close(pin[0]);
107: }
108: close(pout[0]);
109: if (dup2(pout[1], 1) < 0)
110: perror("dup2 stdout");
111: /* Cannot be 1 because pin allocated two descriptors. */
112: close(pout[1]);
113:
114: /* Stderr is left as it is so that error messages get
115: printed on the user's terminal. */
1.89 markus 116: argv[0] = _PATH_BSHELL;
1.38 markus 117: argv[1] = "-c";
118: argv[2] = command_string;
119: argv[3] = NULL;
120:
121: /* Execute the proxy command. Note that we gave up any
122: extra privileges above. */
1.89 markus 123: execv(argv[0], argv);
124: perror(argv[0]);
1.38 markus 125: exit(1);
126: }
127: /* Parent. */
128: if (pid < 0)
129: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 130: else
131: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 132:
133: /* Close child side of the descriptors. */
134: close(pin[0]);
135: close(pout[1]);
136:
137: /* Free the command name. */
1.164 djm 138: xfree(command_string);
1.38 markus 139:
140: /* Set the connection file descriptors. */
141: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 142:
1.110 markus 143: /* Indicate OK return */
144: return 0;
1.1 deraadt 145: }
146:
1.39 deraadt 147: /*
148: * Creates a (possibly privileged) socket for use as the ssh connection.
149: */
1.109 itojun 150: static int
1.139 markus 151: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 152: {
1.105 markus 153: int sock, gaierr;
154: struct addrinfo hints, *res;
1.1 deraadt 155:
1.40 markus 156: /*
157: * If we are running as root and want to connect to a privileged
158: * port, bind our own socket to a privileged port.
159: */
1.38 markus 160: if (privileged) {
161: int p = IPPORT_RESERVED - 1;
1.124 markus 162: PRIV_START;
1.139 markus 163: sock = rresvport_af(&p, ai->ai_family);
1.124 markus 164: PRIV_END;
1.38 markus 165: if (sock < 0)
1.139 markus 166: error("rresvport: af=%d %.100s", ai->ai_family,
167: strerror(errno));
1.55 markus 168: else
169: debug("Allocated local port %d.", p);
1.105 markus 170: return sock;
171: }
1.139 markus 172: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.105 markus 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));
1.139 markus 181: hints.ai_family = ai->ai_family;
182: hints.ai_socktype = ai->ai_socktype;
183: hints.ai_protocol = ai->ai_protocol;
1.105 markus 184: hints.ai_flags = AI_PASSIVE;
185: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
186: if (gaierr) {
187: error("getaddrinfo: %s: %s", options.bind_address,
188: gai_strerror(gaierr));
189: close(sock);
190: return -1;
191: }
192: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
193: error("bind: %s: %s", options.bind_address, strerror(errno));
194: close(sock);
195: freeaddrinfo(res);
196: return -1;
1.38 markus 197: }
1.105 markus 198: freeaddrinfo(res);
1.38 markus 199: return sock;
1.1 deraadt 200: }
201:
1.141 djm 202: static int
203: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
204: socklen_t addrlen, int timeout)
205: {
206: fd_set *fdset;
207: struct timeval tv;
208: socklen_t optlen;
1.142 djm 209: int fdsetsz, optval, rc, result = -1;
1.141 djm 210:
211: if (timeout <= 0)
212: return (connect(sockfd, serv_addr, addrlen));
213:
1.156 djm 214: set_nonblock(sockfd);
1.141 djm 215: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 216: if (rc == 0) {
217: unset_nonblock(sockfd);
1.141 djm 218: return (0);
1.156 djm 219: }
1.141 djm 220: if (errno != EINPROGRESS)
221: return (-1);
222:
223: fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask);
224: fdset = (fd_set *)xmalloc(fdsetsz);
225:
1.147 markus 226: memset(fdset, 0, fdsetsz);
1.141 djm 227: FD_SET(sockfd, fdset);
228: tv.tv_sec = timeout;
229: tv.tv_usec = 0;
230:
1.162 deraadt 231: for (;;) {
1.141 djm 232: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
233: if (rc != -1 || errno != EINTR)
234: break;
235: }
236:
1.162 deraadt 237: switch (rc) {
1.141 djm 238: case 0:
239: /* Timed out */
240: errno = ETIMEDOUT;
1.142 djm 241: break;
1.141 djm 242: case -1:
243: /* Select error */
1.154 djm 244: debug("select: %s", strerror(errno));
1.142 djm 245: break;
1.141 djm 246: case 1:
247: /* Completed or failed */
248: optval = 0;
249: optlen = sizeof(optval);
1.154 djm 250: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 251: &optlen) == -1) {
1.154 djm 252: debug("getsockopt: %s", strerror(errno));
1.142 djm 253: break;
1.148 markus 254: }
1.141 djm 255: if (optval != 0) {
256: errno = optval;
1.142 djm 257: break;
1.141 djm 258: }
1.142 djm 259: result = 0;
1.156 djm 260: unset_nonblock(sockfd);
1.141 djm 261: break;
262: default:
263: /* Should not occur */
264: fatal("Bogus return (%d) from select()", rc);
265: }
266:
1.142 djm 267: xfree(fdset);
268: return (result);
1.141 djm 269: }
270:
1.39 deraadt 271: /*
1.49 markus 272: * Opens a TCP/IP connection to the remote server on the given host.
273: * The address of the remote host will be returned in hostaddr.
1.124 markus 274: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 275: * a privileged port will be allocated to make the connection.
1.124 markus 276: * This requires super-user privileges if needpriv is true.
1.39 deraadt 277: * Connection_attempts specifies the maximum number of tries (one per
278: * second). If proxy_command is non-NULL, it specifies the command (with %h
279: * and %p substituted for host and port, respectively) to use to contact
280: * the daemon.
281: */
1.38 markus 282: int
1.49 markus 283: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 284: u_short port, int family, int connection_attempts,
1.124 markus 285: int needpriv, const char *proxy_command)
1.1 deraadt 286: {
1.90 markus 287: int gaierr;
288: int on = 1;
1.49 markus 289: int sock = -1, attempt;
1.90 markus 290: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 291: struct addrinfo hints, *ai, *aitop;
1.38 markus 292:
1.136 markus 293: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 294:
295: /* If a proxy command is given, connect using it. */
296: if (proxy_command != NULL)
1.124 markus 297: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 298:
299: /* No proxy command. */
300:
1.49 markus 301: memset(&hints, 0, sizeof(hints));
1.115 markus 302: hints.ai_family = family;
1.49 markus 303: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 304: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 305: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 306: fatal("%s: %.100s: %s", __progname, host,
307: gai_strerror(gaierr));
1.38 markus 308:
1.46 markus 309: /*
310: * Try to connect several times. On some machines, the first time
311: * will sometimes fail. In general socket code appears to behave
312: * quite magically on many machines.
1.110 markus 313: */
314: for (attempt = 0; ;) {
1.38 markus 315: if (attempt > 0)
316: debug("Trying again...");
317:
1.49 markus 318: /* Loop through addresses for this host, and try each one in
1.68 markus 319: sequence until the connection succeeds. */
1.49 markus 320: for (ai = aitop; ai; ai = ai->ai_next) {
321: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
322: continue;
323: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
324: ntop, sizeof(ntop), strport, sizeof(strport),
325: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
326: error("ssh_connect: getnameinfo failed");
327: continue;
328: }
329: debug("Connecting to %.200s [%.100s] port %s.",
330: host, ntop, strport);
331:
332: /* Create a socket for connecting. */
1.139 markus 333: sock = ssh_create_socket(needpriv, ai);
1.49 markus 334: if (sock < 0)
1.110 markus 335: /* Any error is already output */
1.49 markus 336: continue;
337:
1.141 djm 338: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
339: options.connection_timeout) >= 0) {
1.49 markus 340: /* Successful connection. */
1.102 markus 341: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 342: break;
1.49 markus 343: } else {
1.131 itojun 344: debug("connect to address %s port %s: %s",
345: ntop, strport, strerror(errno));
1.40 markus 346: /*
347: * Close the failed socket; there appear to
348: * be some problems when reusing a socket for
349: * which connect() has already returned an
350: * error.
351: */
1.38 markus 352: close(sock);
353: }
354: }
1.49 markus 355: if (ai)
356: break; /* Successful connection. */
1.1 deraadt 357:
1.110 markus 358: attempt++;
359: if (attempt >= connection_attempts)
360: break;
1.38 markus 361: /* Sleep a moment before retrying. */
362: sleep(1);
363: }
1.49 markus 364:
365: freeaddrinfo(aitop);
366:
1.38 markus 367: /* Return failure if we didn't get a successful connection. */
1.130 itojun 368: if (attempt >= connection_attempts) {
1.159 markus 369: error("ssh: connect to host %s port %s: %s",
1.130 itojun 370: host, strport, strerror(errno));
1.159 markus 371: return (-1);
1.130 itojun 372: }
1.38 markus 373:
374: debug("Connection established.");
1.90 markus 375:
1.155 markus 376: /* Set SO_KEEPALIVE if requested. */
377: if (options.tcp_keep_alive &&
1.90 markus 378: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
379: sizeof(on)) < 0)
380: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 381:
382: /* Set the connection. */
383: packet_set_connection(sock, sock);
1.1 deraadt 384:
1.110 markus 385: return 0;
1.59 markus 386: }
387:
1.43 markus 388: /*
1.39 deraadt 389: * Waits for the server identification string, and sends our own
390: * identification string.
391: */
1.109 itojun 392: static void
1.95 itojun 393: ssh_exchange_identification(void)
1.1 deraadt 394: {
1.38 markus 395: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 396: int remote_major, remote_minor, mismatch;
1.38 markus 397: int connection_in = packet_get_connection_in();
398: int connection_out = packet_get_connection_out();
1.93 stevesk 399: int minor1 = PROTOCOL_MINOR_1;
1.165 djm 400: u_int i;
1.38 markus 401:
1.163 avsm 402: /* Read other side's version identification. */
1.75 markus 403: for (;;) {
404: for (i = 0; i < sizeof(buf) - 1; i++) {
1.163 avsm 405: size_t len = atomicio(read, connection_in, &buf[i], 1);
406:
1.167 djm 407: if (len != 1 && errno == EPIPE)
1.163 avsm 408: fatal("ssh_exchange_identification: Connection closed by remote host");
409: else if (len != 1)
1.75 markus 410: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
411: if (buf[i] == '\r') {
412: buf[i] = '\n';
413: buf[i + 1] = 0;
414: continue; /**XXX wait for \n */
415: }
416: if (buf[i] == '\n') {
417: buf[i + 1] = 0;
418: break;
419: }
1.38 markus 420: }
1.75 markus 421: buf[sizeof(buf) - 1] = 0;
1.76 markus 422: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 423: break;
1.75 markus 424: debug("ssh_exchange_identification: %s", buf);
1.38 markus 425: }
1.59 markus 426: server_version_string = xstrdup(buf);
1.38 markus 427:
1.40 markus 428: /*
429: * Check that the versions match. In future this might accept
430: * several versions and set appropriate flags to handle them.
431: */
1.59 markus 432: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
433: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 434: fatal("Bad remote protocol version identification: '%.100s'", buf);
435: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 436: remote_major, remote_minor, remote_version);
1.38 markus 437:
1.59 markus 438: compat_datafellows(remote_version);
1.64 markus 439: mismatch = 0;
1.59 markus 440:
1.116 deraadt 441: switch (remote_major) {
1.64 markus 442: case 1:
443: if (remote_minor == 99 &&
444: (options.protocol & SSH_PROTO_2) &&
445: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
446: enable_compat20();
447: break;
448: }
449: if (!(options.protocol & SSH_PROTO_1)) {
450: mismatch = 1;
451: break;
452: }
453: if (remote_minor < 3) {
454: fatal("Remote machine has too old SSH software version.");
1.81 markus 455: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 456: /* We speak 1.3, too. */
457: enable_compat13();
1.81 markus 458: minor1 = 3;
1.64 markus 459: if (options.forward_agent) {
1.138 itojun 460: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 461: options.forward_agent = 0;
462: }
463: }
464: break;
465: case 2:
466: if (options.protocol & SSH_PROTO_2) {
467: enable_compat20();
468: break;
1.38 markus 469: }
1.64 markus 470: /* FALLTHROUGH */
1.68 markus 471: default:
1.64 markus 472: mismatch = 1;
473: break;
1.38 markus 474: }
1.64 markus 475: if (mismatch)
1.38 markus 476: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 477: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
478: remote_major);
1.38 markus 479: /* Send our own protocol version identification. */
480: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 481: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 482: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 483: SSH_VERSION);
1.146 deraadt 484: if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 485: fatal("write: %.100s", strerror(errno));
1.59 markus 486: client_version_string = xstrdup(buf);
487: chop(client_version_string);
488: chop(server_version_string);
489: debug("Local version string %.100s", client_version_string);
1.1 deraadt 490: }
491:
1.96 markus 492: /* defaults to 'no' */
1.109 itojun 493: static int
1.112 markus 494: confirm(const char *prompt)
1.1 deraadt 495: {
1.119 markus 496: const char *msg, *again = "Please type 'yes' or 'no': ";
497: char *p;
498: int ret = -1;
1.96 markus 499:
500: if (options.batch_mode)
501: return 0;
1.119 markus 502: for (msg = prompt;;msg = again) {
503: p = read_passphrase(msg, RP_ECHO);
504: if (p == NULL ||
505: (p[0] == '\0') || (p[0] == '\n') ||
506: strncasecmp(p, "no", 2) == 0)
507: ret = 0;
1.127 markus 508: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 509: ret = 1;
510: if (p)
511: xfree(p);
512: if (ret != -1)
513: return ret;
1.1 deraadt 514: }
515: }
516:
1.39 deraadt 517: /*
1.108 markus 518: * check whether the supplied host key is valid, return -1 if the key
519: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 520: */
1.109 itojun 521: static int
1.70 markus 522: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 523: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 524: {
1.58 markus 525: Key *file_key;
1.152 jakob 526: const char *type = key_type(host_key);
1.46 markus 527: char *ip = NULL;
1.100 markus 528: char hostline[1000], *hostp, *fp;
1.38 markus 529: HostStatus host_status;
530: HostStatus ip_status;
1.161 djm 531: int r, local = 0, host_ip_differ = 0;
1.49 markus 532: char ntop[NI_MAXHOST];
1.119 markus 533: char msg[1024];
1.145 jakob 534: int len, host_line, ip_line;
1.85 markus 535: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 536:
537: /*
538: * Force accepting of the host key for loopback/localhost. The
539: * problem is that if the home directory is NFS-mounted to multiple
540: * machines, localhost will refer to a different machine in each of
541: * them, and the user will get bogus HOST_CHANGED warnings. This
542: * essentially disables host authentication for localhost; however,
543: * this is probably not a real problem.
544: */
1.70 markus 545: /** hostaddr == 0! */
1.49 markus 546: switch (hostaddr->sa_family) {
547: case AF_INET:
1.108 markus 548: local = (ntohl(((struct sockaddr_in *)hostaddr)->
1.168 djm 549: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 550: break;
551: case AF_INET6:
1.108 markus 552: local = IN6_IS_ADDR_LOOPBACK(
553: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 554: break;
555: default:
556: local = 0;
557: break;
558: }
1.111 markus 559: if (options.no_host_authentication_for_localhost == 1 && local &&
560: options.host_key_alias == NULL) {
1.88 markus 561: debug("Forcing accepting of host key for "
562: "loopback/localhost.");
1.108 markus 563: return 0;
1.49 markus 564: }
1.42 markus 565:
566: /*
1.88 markus 567: * We don't have the remote ip-address for connections
568: * using a proxy command
1.42 markus 569: */
1.84 markus 570: if (options.proxy_command == NULL) {
571: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 572: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 573: fatal("check_host_key: getnameinfo failed");
574: ip = xstrdup(ntop);
575: } else {
576: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 577: }
1.88 markus 578: /*
579: * Turn off check_host_ip if the connection is to localhost, via proxy
580: * command or if we don't have a hostname to compare with
581: */
582: if (options.check_host_ip &&
583: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
584: options.check_host_ip = 0;
1.86 markus 585:
586: /*
587: * Allow the user to record the key under a different name. This is
588: * useful for ssh tunneling over forwarded connections or if you run
589: * multiple sshd's on different ports on the same machine.
590: */
591: if (options.host_key_alias != NULL) {
592: host = options.host_key_alias;
593: debug("using hostkeyalias: %s", host);
1.84 markus 594: }
1.38 markus 595:
1.46 markus 596: /*
597: * Store the host key from the known host file in here so that we can
598: * compare it with the key for the IP address.
599: */
1.58 markus 600: file_key = key_new(host_key->type);
1.38 markus 601:
1.40 markus 602: /*
1.170 djm 603: * Check if the host key is present in the user's list of known
1.40 markus 604: * hosts or in the systemwide list.
605: */
1.85 markus 606: host_file = user_hostfile;
1.108 markus 607: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 608: file_key, &host_line);
1.85 markus 609: if (host_status == HOST_NEW) {
610: host_file = system_hostfile;
1.108 markus 611: host_status = check_host_in_hostfile(host_file, host, host_key,
612: file_key, &host_line);
1.85 markus 613: }
1.40 markus 614: /*
615: * Also perform check for the ip address, skip the check if we are
616: * localhost or the hostname was an ip address to begin with
617: */
1.88 markus 618: if (options.check_host_ip) {
1.58 markus 619: Key *ip_key = key_new(host_key->type);
1.38 markus 620:
1.85 markus 621: ip_file = user_hostfile;
1.108 markus 622: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
623: ip_key, &ip_line);
1.85 markus 624: if (ip_status == HOST_NEW) {
625: ip_file = system_hostfile;
1.108 markus 626: ip_status = check_host_in_hostfile(ip_file, ip,
627: host_key, ip_key, &ip_line);
1.85 markus 628: }
1.38 markus 629: if (host_status == HOST_CHANGED &&
1.58 markus 630: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 631: host_ip_differ = 1;
632:
1.58 markus 633: key_free(ip_key);
1.38 markus 634: } else
635: ip_status = host_status;
636:
1.58 markus 637: key_free(file_key);
1.38 markus 638:
639: switch (host_status) {
640: case HOST_OK:
641: /* The host is known and the key matches. */
1.72 markus 642: debug("Host '%.200s' is known and matches the %s host key.",
643: host, type);
1.85 markus 644: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 645: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 646: if (readonly)
1.138 itojun 647: logit("%s host key for IP address "
1.108 markus 648: "'%.128s' not in list of known hosts.",
649: type, ip);
650: else if (!add_host_to_hostfile(user_hostfile, ip,
1.160 djm 651: host_key, options.hash_known_hosts))
1.138 itojun 652: logit("Failed to add the %s host key for IP "
1.108 markus 653: "address '%.128s' to the list of known "
654: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 655: else
1.138 itojun 656: logit("Warning: Permanently added the %s host "
1.108 markus 657: "key for IP address '%.128s' to the list "
658: "of known hosts.", type, ip);
1.38 markus 659: }
660: break;
661: case HOST_NEW:
1.108 markus 662: if (readonly)
663: goto fail;
1.38 markus 664: /* The host is new. */
665: if (options.strict_host_key_checking == 1) {
1.108 markus 666: /*
667: * User has requested strict host key checking. We
668: * will not add the host key automatically. The only
669: * alternative left is to abort.
670: */
671: error("No %s host key is known for %.200s and you "
672: "have requested strict checking.", type, host);
673: goto fail;
1.38 markus 674: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 675: char msg1[1024], msg2[1024];
676:
677: if (show_other_keys(host, host_key))
678: snprintf(msg1, sizeof(msg1),
1.168 djm 679: "\nbut keys of different type are already"
680: " known for this host.");
1.145 jakob 681: else
682: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 683: /* The default */
1.100 markus 684: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.145 jakob 685: msg2[0] = '\0';
686: if (options.verify_host_key_dns) {
1.153 jakob 687: if (matching_host_key_dns)
1.145 jakob 688: snprintf(msg2, sizeof(msg2),
689: "Matching host key fingerprint"
690: " found in DNS.\n");
691: else
692: snprintf(msg2, sizeof(msg2),
693: "No matching host key fingerprint"
694: " found in DNS.\n");
695: }
1.119 markus 696: snprintf(msg, sizeof(msg),
1.108 markus 697: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 698: "established%s\n"
1.145 jakob 699: "%s key fingerprint is %s.\n%s"
1.108 markus 700: "Are you sure you want to continue connecting "
1.132 markus 701: "(yes/no)? ",
1.145 jakob 702: host, ip, msg1, type, fp, msg2);
1.100 markus 703: xfree(fp);
1.119 markus 704: if (!confirm(msg))
1.108 markus 705: goto fail;
1.38 markus 706: }
1.161 djm 707: /*
708: * If not in strict mode, add the key automatically to the
709: * local known_hosts file.
710: */
1.88 markus 711: if (options.check_host_ip && ip_status == HOST_NEW) {
1.161 djm 712: snprintf(hostline, sizeof(hostline), "%s,%s",
713: host, ip);
1.38 markus 714: hostp = hostline;
1.161 djm 715: if (options.hash_known_hosts) {
716: /* Add hash of host and IP separately */
717: r = add_host_to_hostfile(user_hostfile, host,
718: host_key, options.hash_known_hosts) &&
719: add_host_to_hostfile(user_hostfile, ip,
720: host_key, options.hash_known_hosts);
721: } else {
722: /* Add unhashed "host,ip" */
723: r = add_host_to_hostfile(user_hostfile,
724: hostline, host_key,
725: options.hash_known_hosts);
726: }
727: } else {
728: r = add_host_to_hostfile(user_hostfile, host, host_key,
729: options.hash_known_hosts);
1.38 markus 730: hostp = host;
1.161 djm 731: }
1.38 markus 732:
1.161 djm 733: if (!r)
1.138 itojun 734: logit("Failed to add the host to the list of known "
1.108 markus 735: "hosts (%.500s).", user_hostfile);
1.38 markus 736: else
1.138 itojun 737: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 738: "list of known hosts.", hostp, type);
1.38 markus 739: break;
740: case HOST_CHANGED:
741: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 742: char *key_msg;
1.38 markus 743: if (ip_status == HOST_NEW)
1.158 avsm 744: key_msg = "is unknown";
1.38 markus 745: else if (ip_status == HOST_OK)
1.158 avsm 746: key_msg = "is unchanged";
1.38 markus 747: else
1.158 avsm 748: key_msg = "has a different value";
1.38 markus 749: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
750: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
751: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 752: error("The %s host key for %s has changed,", type, host);
1.38 markus 753: error("and the key for the according IP address %s", ip);
1.158 avsm 754: error("%s. This could either mean that", key_msg);
1.38 markus 755: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 756: error("and its host key have changed at the same time.");
1.88 markus 757: if (ip_status != HOST_NEW)
1.85 markus 758: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 759: }
760: /* The host key has changed. */
1.150 jakob 761: warn_changed_key(host_key);
1.38 markus 762: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 763: user_hostfile);
1.85 markus 764: error("Offending key in %s:%d", host_file, host_line);
1.38 markus 765:
1.40 markus 766: /*
767: * If strict host key checking is in use, the user will have
768: * to edit the key manually and we can only abort.
769: */
1.108 markus 770: if (options.strict_host_key_checking) {
771: error("%s host key for %.200s has changed and you have "
772: "requested strict checking.", type, host);
773: goto fail;
774: }
1.38 markus 775:
1.40 markus 776: /*
777: * If strict host key checking has not been requested, allow
1.144 djm 778: * the connection but without MITM-able authentication or
1.40 markus 779: * agent forwarding.
780: */
1.38 markus 781: if (options.password_authentication) {
1.108 markus 782: error("Password authentication is disabled to avoid "
783: "man-in-the-middle attacks.");
1.38 markus 784: options.password_authentication = 0;
1.144 djm 785: }
786: if (options.kbd_interactive_authentication) {
787: error("Keyboard-interactive authentication is disabled"
788: " to avoid man-in-the-middle attacks.");
789: options.kbd_interactive_authentication = 0;
790: options.challenge_response_authentication = 0;
791: }
792: if (options.challenge_response_authentication) {
793: error("Challenge/response authentication is disabled"
794: " to avoid man-in-the-middle attacks.");
795: options.challenge_response_authentication = 0;
1.38 markus 796: }
797: if (options.forward_agent) {
1.108 markus 798: error("Agent forwarding is disabled to avoid "
799: "man-in-the-middle attacks.");
1.38 markus 800: options.forward_agent = 0;
1.83 markus 801: }
802: if (options.forward_x11) {
1.108 markus 803: error("X11 forwarding is disabled to avoid "
804: "man-in-the-middle attacks.");
1.83 markus 805: options.forward_x11 = 0;
806: }
1.108 markus 807: if (options.num_local_forwards > 0 ||
808: options.num_remote_forwards > 0) {
809: error("Port forwarding is disabled to avoid "
810: "man-in-the-middle attacks.");
811: options.num_local_forwards =
1.118 deraadt 812: options.num_remote_forwards = 0;
1.38 markus 813: }
1.40 markus 814: /*
815: * XXX Should permit the user to change to use the new id.
816: * This could be done by converting the host key to an
817: * identifying sentence, tell that the host identifies itself
818: * by that sentence, and ask the user if he/she whishes to
819: * accept the authentication.
820: */
1.38 markus 821: break;
1.132 markus 822: case HOST_FOUND:
823: fatal("internal error");
824: break;
1.88 markus 825: }
826:
827: if (options.check_host_ip && host_status != HOST_CHANGED &&
828: ip_status == HOST_CHANGED) {
1.119 markus 829: snprintf(msg, sizeof(msg),
830: "Warning: the %s host key for '%.200s' "
831: "differs from the key for the IP address '%.128s'"
832: "\nOffending key for IP in %s:%d",
833: type, host, ip, ip_file, ip_line);
834: if (host_status == HOST_OK) {
835: len = strlen(msg);
836: snprintf(msg + len, sizeof(msg) - len,
837: "\nMatching host key in %s:%d",
1.125 deraadt 838: host_file, host_line);
1.119 markus 839: }
1.88 markus 840: if (options.strict_host_key_checking == 1) {
1.143 djm 841: logit("%s", msg);
1.108 markus 842: error("Exiting, you have requested strict checking.");
843: goto fail;
1.88 markus 844: } else if (options.strict_host_key_checking == 2) {
1.119 markus 845: strlcat(msg, "\nAre you sure you want "
846: "to continue connecting (yes/no)? ", sizeof(msg));
847: if (!confirm(msg))
1.108 markus 848: goto fail;
1.119 markus 849: } else {
1.143 djm 850: logit("%s", msg);
1.88 markus 851: }
1.38 markus 852: }
1.82 provos 853:
854: xfree(ip);
1.108 markus 855: return 0;
856:
857: fail:
858: xfree(ip);
859: return -1;
860: }
861:
1.140 jakob 862: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 863: int
864: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
865: {
866: struct stat st;
1.153 jakob 867: int flags = 0;
1.140 jakob 868:
1.153 jakob 869: if (options.verify_host_key_dns &&
870: verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
871:
872: if (flags & DNS_VERIFY_FOUND) {
873:
874: if (options.verify_host_key_dns == 1 &&
875: flags & DNS_VERIFY_MATCH &&
876: flags & DNS_VERIFY_SECURE)
877: return 0;
878:
879: if (flags & DNS_VERIFY_MATCH) {
880: matching_host_key_dns = 1;
881: } else {
882: warn_changed_key(host_key);
883: error("Update the SSHFP RR in DNS with the new "
884: "host key to get rid of this message.");
885: }
1.140 jakob 886: }
887: }
1.108 markus 888:
889: /* return ok if the key can be found in an old keyfile */
890: if (stat(options.system_hostfile2, &st) == 0 ||
891: stat(options.user_hostfile2, &st) == 0) {
892: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
893: options.user_hostfile2, options.system_hostfile2) == 0)
894: return 0;
895: }
896: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
897: options.user_hostfile, options.system_hostfile);
1.51 markus 898: }
1.70 markus 899:
1.51 markus 900: /*
901: * Starts a dialog with the server, and authenticates the current user on the
902: * server. This does not need any extra privileges. The basic connection
903: * to the server must already have been established before this is called.
904: * If login fails, this function prints an error and never returns.
905: * This function does not require super-user privileges.
906: */
907: void
1.120 markus 908: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 909: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 910: {
911: char *host, *cp;
1.70 markus 912: char *server_user, *local_user;
913:
914: local_user = xstrdup(pw->pw_name);
915: server_user = options.user ? options.user : local_user;
1.51 markus 916:
917: /* Convert the user-supplied hostname into all lowercase. */
918: host = xstrdup(orighost);
919: for (cp = host; *cp; cp++)
920: if (isupper(*cp))
921: *cp = tolower(*cp);
922:
923: /* Exchange protocol version identification strings with the server. */
924: ssh_exchange_identification();
925:
926: /* Put the connection into non-blocking mode. */
927: packet_set_nonblocking();
928:
929: /* key exchange */
930: /* authenticate user */
1.59 markus 931: if (compat20) {
932: ssh_kex2(host, hostaddr);
1.120 markus 933: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 934: } else {
935: ssh_kex(host, hostaddr);
1.120 markus 936: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 937: }
1.97 markus 938: }
939:
940: void
941: ssh_put_password(char *password)
942: {
943: int size;
944: char *padded;
945:
1.99 deraadt 946: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 947: packet_put_cstring(password);
1.99 deraadt 948: return;
949: }
1.97 markus 950: size = roundup(strlen(password) + 1, 32);
951: padded = xmalloc(size);
952: memset(padded, 0, size);
953: strlcpy(padded, password, size);
954: packet_put_string(padded, size);
955: memset(padded, 0, size);
956: xfree(padded);
1.132 markus 957: }
958:
959: static int
960: show_key_from_file(const char *file, const char *host, int keytype)
961: {
962: Key *found;
963: char *fp;
964: int line, ret;
965:
966: found = key_new(keytype);
967: if ((ret = lookup_key_in_hostfile_by_type(file, host,
968: keytype, found, &line))) {
969: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 970: logit("WARNING: %s key found for host %s\n"
1.133 markus 971: "in %s:%d\n"
1.132 markus 972: "%s key fingerprint %s.",
973: key_type(found), host, file, line,
974: key_type(found), fp);
975: xfree(fp);
976: }
977: key_free(found);
978: return (ret);
979: }
980:
981: /* print all known host keys for a given host, but skip keys of given type */
982: static int
983: show_other_keys(const char *host, Key *key)
984: {
985: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
986: int i, found = 0;
987:
988: for (i = 0; type[i] != -1; i++) {
989: if (type[i] == key->type)
990: continue;
991: if (type[i] != KEY_RSA1 &&
992: show_key_from_file(options.user_hostfile2, host, type[i])) {
993: found = 1;
994: continue;
995: }
996: if (type[i] != KEY_RSA1 &&
997: show_key_from_file(options.system_hostfile2, host, type[i])) {
998: found = 1;
999: continue;
1000: }
1001: if (show_key_from_file(options.user_hostfile, host, type[i])) {
1002: found = 1;
1003: continue;
1004: }
1005: if (show_key_from_file(options.system_hostfile, host, type[i])) {
1006: found = 1;
1007: continue;
1008: }
1009: debug2("no key of type %d for host %s", type[i], host);
1010: }
1011: return (found);
1.150 jakob 1012: }
1013:
1014: static void
1015: warn_changed_key(Key *host_key)
1016: {
1017: char *fp;
1.151 jakob 1018: const char *type = key_type(host_key);
1.150 jakob 1019:
1020: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1021:
1022: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1023: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1024: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1025: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1026: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1027: error("It is also possible that the %s host key has just been changed.", type);
1028: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1029: type, fp);
1030: error("Please contact your system administrator.");
1031:
1032: xfree(fp);
1.171 reyk 1033: }
1034:
1035: /*
1036: * Execute a local command
1037: */
1038: int
1039: ssh_local_cmd(const char *args)
1040: {
1041: char *shell;
1042: pid_t pid;
1043: int status;
1044:
1045: if (!options.permit_local_command ||
1046: args == NULL || !*args)
1047: return (1);
1048:
1049: if ((shell = getenv("SHELL")) == NULL)
1050: shell = _PATH_BSHELL;
1051:
1052: pid = fork();
1053: if (pid == 0) {
1054: debug3("Executing %s -c \"%s\"", shell, args);
1055: execl(shell, shell, "-c", args, (char *)NULL);
1056: error("Couldn't execute %s -c \"%s\": %s",
1057: shell, args, strerror(errno));
1058: _exit(1);
1059: } else if (pid == -1)
1060: fatal("fork failed: %.100s", strerror(errno));
1061: while (waitpid(pid, &status, 0) == -1)
1062: if (errno != EINTR)
1063: fatal("Couldn't wait for child: %s", strerror(errno));
1064:
1065: if (!WIFEXITED(status))
1066: return (1);
1067:
1068: return (WEXITSTATUS(status));
1.1 deraadt 1069: }
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