Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.191
1.191 ! stevesk 1: /* $OpenBSD: sshconnect.c,v 1.190 2006/07/11 20:07:25 stevesk Exp $ */
1.1 deraadt 2: /*
1.39 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
1.78 deraadt 8: *
9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 14: */
1.1 deraadt 15:
16: #include "includes.h"
1.174 stevesk 17:
18: #include <sys/types.h>
19: #include <sys/wait.h>
1.175 stevesk 20: #include <sys/stat.h>
1.187 stevesk 21: #include <sys/socket.h>
22:
23: #include <netinet/in.h>
1.172 stevesk 24:
1.176 stevesk 25: #include <ctype.h>
1.190 stevesk 26: #include <errno.h>
1.191 ! stevesk 27: #include <netdb.h>
1.172 stevesk 28: #include <paths.h>
1.188 stevesk 29: #include <pwd.h>
1.71 markus 30:
1.91 markus 31: #include "ssh.h"
1.1 deraadt 32: #include "xmalloc.h"
33: #include "rsa.h"
1.59 markus 34: #include "buffer.h"
1.1 deraadt 35: #include "packet.h"
36: #include "uidswap.h"
1.21 markus 37: #include "compat.h"
1.58 markus 38: #include "key.h"
1.71 markus 39: #include "sshconnect.h"
1.58 markus 40: #include "hostfile.h"
1.91 markus 41: #include "log.h"
42: #include "readconf.h"
43: #include "atomicio.h"
44: #include "misc.h"
1.140 jakob 45: #include "dns.h"
1.186 stevesk 46: #include "version.h"
1.140 jakob 47:
1.70 markus 48: char *client_version_string = NULL;
49: char *server_version_string = NULL;
1.59 markus 50:
1.169 stevesk 51: static int matching_host_key_dns = 0;
1.145 jakob 52:
1.124 markus 53: /* import */
1.43 markus 54: extern Options options;
1.50 markus 55: extern char *__progname;
1.124 markus 56: extern uid_t original_real_uid;
57: extern uid_t original_effective_uid;
1.135 djm 58: extern pid_t proxy_command_pid;
1.91 markus 59:
1.132 markus 60: static int show_other_keys(const char *, Key *);
1.150 jakob 61: static void warn_changed_key(Key *);
1.132 markus 62:
1.39 deraadt 63: /*
64: * Connect to the given ssh server using a proxy command.
65: */
1.109 itojun 66: static int
1.124 markus 67: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 68: {
1.164 djm 69: char *command_string, *tmp;
1.38 markus 70: int pin[2], pout[2];
1.69 deraadt 71: pid_t pid;
1.49 markus 72: char strport[NI_MAXSERV];
1.38 markus 73:
74: /* Convert the port number into a string. */
1.49 markus 75: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 76:
1.135 djm 77: /*
78: * Build the final command string in the buffer by making the
79: * appropriate substitutions to the given proxy command.
80: *
1.154 djm 81: * Use "exec" to avoid "sh -c" processes on some platforms
1.135 djm 82: * (e.g. Solaris)
83: */
1.179 djm 84: xasprintf(&tmp, "exec %s", proxy_command);
1.164 djm 85: command_string = percent_expand(tmp, "h", host,
86: "p", strport, (char *)NULL);
87: xfree(tmp);
1.38 markus 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. */
1.184 markus 101: permanently_drop_suid(original_real_uid);
1.38 markus 102:
103: /* Redirect stdin and stdout. */
104: close(pin[1]);
105: if (pin[0] != 0) {
106: if (dup2(pin[0], 0) < 0)
107: perror("dup2 stdin");
108: close(pin[0]);
109: }
110: close(pout[0]);
111: if (dup2(pout[1], 1) < 0)
112: perror("dup2 stdout");
113: /* Cannot be 1 because pin allocated two descriptors. */
114: close(pout[1]);
115:
116: /* Stderr is left as it is so that error messages get
117: printed on the user's terminal. */
1.89 markus 118: argv[0] = _PATH_BSHELL;
1.38 markus 119: argv[1] = "-c";
120: argv[2] = command_string;
121: argv[3] = NULL;
122:
123: /* Execute the proxy command. Note that we gave up any
124: extra privileges above. */
1.89 markus 125: execv(argv[0], argv);
126: perror(argv[0]);
1.38 markus 127: exit(1);
128: }
129: /* Parent. */
130: if (pid < 0)
131: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 132: else
133: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 134:
135: /* Close child side of the descriptors. */
136: close(pin[0]);
137: close(pout[1]);
138:
139: /* Free the command name. */
1.164 djm 140: xfree(command_string);
1.38 markus 141:
142: /* Set the connection file descriptors. */
143: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 144:
1.110 markus 145: /* Indicate OK return */
146: return 0;
1.1 deraadt 147: }
148:
1.39 deraadt 149: /*
150: * Creates a (possibly privileged) socket for use as the ssh connection.
151: */
1.109 itojun 152: static int
1.139 markus 153: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 154: {
1.105 markus 155: int sock, gaierr;
156: struct addrinfo hints, *res;
1.1 deraadt 157:
1.40 markus 158: /*
159: * If we are running as root and want to connect to a privileged
160: * port, bind our own socket to a privileged port.
161: */
1.38 markus 162: if (privileged) {
163: int p = IPPORT_RESERVED - 1;
1.124 markus 164: PRIV_START;
1.139 markus 165: sock = rresvport_af(&p, ai->ai_family);
1.124 markus 166: PRIV_END;
1.38 markus 167: if (sock < 0)
1.139 markus 168: error("rresvport: af=%d %.100s", ai->ai_family,
169: strerror(errno));
1.55 markus 170: else
171: debug("Allocated local port %d.", p);
1.105 markus 172: return sock;
173: }
1.139 markus 174: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.105 markus 175: if (sock < 0)
176: error("socket: %.100s", strerror(errno));
177:
178: /* Bind the socket to an alternative local IP address */
179: if (options.bind_address == NULL)
180: return sock;
181:
182: memset(&hints, 0, sizeof(hints));
1.139 markus 183: hints.ai_family = ai->ai_family;
184: hints.ai_socktype = ai->ai_socktype;
185: hints.ai_protocol = ai->ai_protocol;
1.105 markus 186: hints.ai_flags = AI_PASSIVE;
187: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
188: if (gaierr) {
189: error("getaddrinfo: %s: %s", options.bind_address,
190: gai_strerror(gaierr));
191: close(sock);
192: return -1;
193: }
194: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
195: error("bind: %s: %s", options.bind_address, strerror(errno));
196: close(sock);
197: freeaddrinfo(res);
198: return -1;
1.38 markus 199: }
1.105 markus 200: freeaddrinfo(res);
1.38 markus 201: return sock;
1.1 deraadt 202: }
203:
1.141 djm 204: static int
205: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
206: socklen_t addrlen, int timeout)
207: {
208: fd_set *fdset;
209: struct timeval tv;
210: socklen_t optlen;
1.179 djm 211: int optval, rc, result = -1;
1.141 djm 212:
213: if (timeout <= 0)
214: return (connect(sockfd, serv_addr, addrlen));
215:
1.156 djm 216: set_nonblock(sockfd);
1.141 djm 217: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 218: if (rc == 0) {
219: unset_nonblock(sockfd);
1.141 djm 220: return (0);
1.156 djm 221: }
1.141 djm 222: if (errno != EINPROGRESS)
223: return (-1);
224:
1.179 djm 225: fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
226: sizeof(fd_mask));
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:
1.181 markus 309: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.38 markus 310: if (attempt > 0)
311: debug("Trying again...");
312:
1.181 markus 313: /*
314: * Loop through addresses for this host, and try each one in
315: * sequence until the connection succeeds.
316: */
1.49 markus 317: for (ai = aitop; ai; ai = ai->ai_next) {
318: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
319: continue;
320: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
321: ntop, sizeof(ntop), strport, sizeof(strport),
322: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
323: error("ssh_connect: getnameinfo failed");
324: continue;
325: }
326: debug("Connecting to %.200s [%.100s] port %s.",
327: host, ntop, strport);
328:
329: /* Create a socket for connecting. */
1.139 markus 330: sock = ssh_create_socket(needpriv, ai);
1.49 markus 331: if (sock < 0)
1.110 markus 332: /* Any error is already output */
1.49 markus 333: continue;
334:
1.141 djm 335: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
336: options.connection_timeout) >= 0) {
1.49 markus 337: /* Successful connection. */
1.102 markus 338: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 339: break;
1.49 markus 340: } else {
1.131 itojun 341: debug("connect to address %s port %s: %s",
342: ntop, strport, strerror(errno));
1.38 markus 343: close(sock);
1.181 markus 344: sock = -1;
1.38 markus 345: }
346: }
1.181 markus 347: if (sock != -1)
1.49 markus 348: break; /* Successful connection. */
1.1 deraadt 349:
1.38 markus 350: /* Sleep a moment before retrying. */
351: sleep(1);
352: }
1.49 markus 353:
354: freeaddrinfo(aitop);
355:
1.38 markus 356: /* Return failure if we didn't get a successful connection. */
1.181 markus 357: if (sock == -1) {
1.159 markus 358: error("ssh: connect to host %s port %s: %s",
1.130 itojun 359: host, strport, strerror(errno));
1.159 markus 360: return (-1);
1.130 itojun 361: }
1.38 markus 362:
363: debug("Connection established.");
1.90 markus 364:
1.155 markus 365: /* Set SO_KEEPALIVE if requested. */
366: if (options.tcp_keep_alive &&
1.90 markus 367: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
368: sizeof(on)) < 0)
369: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 370:
371: /* Set the connection. */
372: packet_set_connection(sock, sock);
1.1 deraadt 373:
1.110 markus 374: return 0;
1.59 markus 375: }
376:
1.43 markus 377: /*
1.39 deraadt 378: * Waits for the server identification string, and sends our own
379: * identification string.
380: */
1.109 itojun 381: static void
1.95 itojun 382: ssh_exchange_identification(void)
1.1 deraadt 383: {
1.38 markus 384: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 385: int remote_major, remote_minor, mismatch;
1.38 markus 386: int connection_in = packet_get_connection_in();
387: int connection_out = packet_get_connection_out();
1.93 stevesk 388: int minor1 = PROTOCOL_MINOR_1;
1.185 djm 389: u_int i, n;
1.38 markus 390:
1.163 avsm 391: /* Read other side's version identification. */
1.185 djm 392: for (n = 0;;) {
1.75 markus 393: for (i = 0; i < sizeof(buf) - 1; i++) {
1.163 avsm 394: size_t len = atomicio(read, connection_in, &buf[i], 1);
395:
1.167 djm 396: if (len != 1 && errno == EPIPE)
1.163 avsm 397: fatal("ssh_exchange_identification: Connection closed by remote host");
398: else if (len != 1)
1.75 markus 399: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
400: if (buf[i] == '\r') {
401: buf[i] = '\n';
402: buf[i + 1] = 0;
403: continue; /**XXX wait for \n */
404: }
405: if (buf[i] == '\n') {
406: buf[i + 1] = 0;
407: break;
408: }
1.185 djm 409: if (++n > 65536)
410: fatal("ssh_exchange_identification: No banner received");
1.38 markus 411: }
1.75 markus 412: buf[sizeof(buf) - 1] = 0;
1.76 markus 413: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 414: break;
1.75 markus 415: debug("ssh_exchange_identification: %s", buf);
1.38 markus 416: }
1.59 markus 417: server_version_string = xstrdup(buf);
1.38 markus 418:
1.40 markus 419: /*
420: * Check that the versions match. In future this might accept
421: * several versions and set appropriate flags to handle them.
422: */
1.59 markus 423: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
424: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 425: fatal("Bad remote protocol version identification: '%.100s'", buf);
426: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 427: remote_major, remote_minor, remote_version);
1.38 markus 428:
1.59 markus 429: compat_datafellows(remote_version);
1.64 markus 430: mismatch = 0;
1.59 markus 431:
1.116 deraadt 432: switch (remote_major) {
1.64 markus 433: case 1:
434: if (remote_minor == 99 &&
435: (options.protocol & SSH_PROTO_2) &&
436: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
437: enable_compat20();
438: break;
439: }
440: if (!(options.protocol & SSH_PROTO_1)) {
441: mismatch = 1;
442: break;
443: }
444: if (remote_minor < 3) {
445: fatal("Remote machine has too old SSH software version.");
1.81 markus 446: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 447: /* We speak 1.3, too. */
448: enable_compat13();
1.81 markus 449: minor1 = 3;
1.64 markus 450: if (options.forward_agent) {
1.138 itojun 451: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 452: options.forward_agent = 0;
453: }
454: }
455: break;
456: case 2:
457: if (options.protocol & SSH_PROTO_2) {
458: enable_compat20();
459: break;
1.38 markus 460: }
1.64 markus 461: /* FALLTHROUGH */
1.68 markus 462: default:
1.64 markus 463: mismatch = 1;
464: break;
1.38 markus 465: }
1.64 markus 466: if (mismatch)
1.38 markus 467: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 468: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
469: remote_major);
1.38 markus 470: /* Send our own protocol version identification. */
471: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 472: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 473: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 474: SSH_VERSION);
1.146 deraadt 475: if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 476: fatal("write: %.100s", strerror(errno));
1.59 markus 477: client_version_string = xstrdup(buf);
478: chop(client_version_string);
479: chop(server_version_string);
480: debug("Local version string %.100s", client_version_string);
1.1 deraadt 481: }
482:
1.96 markus 483: /* defaults to 'no' */
1.109 itojun 484: static int
1.112 markus 485: confirm(const char *prompt)
1.1 deraadt 486: {
1.119 markus 487: const char *msg, *again = "Please type 'yes' or 'no': ";
488: char *p;
489: int ret = -1;
1.96 markus 490:
491: if (options.batch_mode)
492: return 0;
1.119 markus 493: for (msg = prompt;;msg = again) {
494: p = read_passphrase(msg, RP_ECHO);
495: if (p == NULL ||
496: (p[0] == '\0') || (p[0] == '\n') ||
497: strncasecmp(p, "no", 2) == 0)
498: ret = 0;
1.127 markus 499: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 500: ret = 1;
501: if (p)
502: xfree(p);
503: if (ret != -1)
504: return ret;
1.1 deraadt 505: }
506: }
507:
1.39 deraadt 508: /*
1.108 markus 509: * check whether the supplied host key is valid, return -1 if the key
510: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 511: */
1.109 itojun 512: static int
1.189 dtucker 513: check_host_key(char *hostname, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 514: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 515: {
1.58 markus 516: Key *file_key;
1.152 jakob 517: const char *type = key_type(host_key);
1.189 dtucker 518: char *ip = NULL, *host = NULL;
1.100 markus 519: char hostline[1000], *hostp, *fp;
1.38 markus 520: HostStatus host_status;
521: HostStatus ip_status;
1.161 djm 522: int r, local = 0, host_ip_differ = 0;
1.49 markus 523: char ntop[NI_MAXHOST];
1.119 markus 524: char msg[1024];
1.145 jakob 525: int len, host_line, ip_line;
1.85 markus 526: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 527:
528: /*
529: * Force accepting of the host key for loopback/localhost. The
530: * problem is that if the home directory is NFS-mounted to multiple
531: * machines, localhost will refer to a different machine in each of
532: * them, and the user will get bogus HOST_CHANGED warnings. This
533: * essentially disables host authentication for localhost; however,
534: * this is probably not a real problem.
535: */
1.70 markus 536: /** hostaddr == 0! */
1.49 markus 537: switch (hostaddr->sa_family) {
538: case AF_INET:
1.108 markus 539: local = (ntohl(((struct sockaddr_in *)hostaddr)->
1.168 djm 540: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 541: break;
542: case AF_INET6:
1.108 markus 543: local = IN6_IS_ADDR_LOOPBACK(
544: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 545: break;
546: default:
547: local = 0;
548: break;
549: }
1.111 markus 550: if (options.no_host_authentication_for_localhost == 1 && local &&
551: options.host_key_alias == NULL) {
1.88 markus 552: debug("Forcing accepting of host key for "
553: "loopback/localhost.");
1.108 markus 554: return 0;
1.49 markus 555: }
1.42 markus 556:
557: /*
1.88 markus 558: * We don't have the remote ip-address for connections
559: * using a proxy command
1.42 markus 560: */
1.84 markus 561: if (options.proxy_command == NULL) {
562: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 563: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 564: fatal("check_host_key: getnameinfo failed");
1.189 dtucker 565: ip = put_host_port(ntop, options.port);
1.84 markus 566: } else {
567: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 568: }
1.88 markus 569: /*
570: * Turn off check_host_ip if the connection is to localhost, via proxy
571: * command or if we don't have a hostname to compare with
572: */
1.189 dtucker 573: if (options.check_host_ip && (local ||
574: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 575: options.check_host_ip = 0;
1.86 markus 576:
577: /*
1.189 dtucker 578: * Allow the user to record the key under a different name or
579: * differentiate a non-standard port. This is useful for ssh
580: * tunneling over forwarded connections or if you run multiple
581: * sshd's on different ports on the same machine.
1.86 markus 582: */
583: if (options.host_key_alias != NULL) {
1.189 dtucker 584: host = xstrdup(options.host_key_alias);
1.86 markus 585: debug("using hostkeyalias: %s", host);
1.189 dtucker 586: } else {
587: host = put_host_port(hostname, options.port);
1.84 markus 588: }
1.38 markus 589:
1.46 markus 590: /*
591: * Store the host key from the known host file in here so that we can
592: * compare it with the key for the IP address.
593: */
1.58 markus 594: file_key = key_new(host_key->type);
1.38 markus 595:
1.40 markus 596: /*
1.170 djm 597: * Check if the host key is present in the user's list of known
1.40 markus 598: * hosts or in the systemwide list.
599: */
1.85 markus 600: host_file = user_hostfile;
1.108 markus 601: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 602: file_key, &host_line);
1.85 markus 603: if (host_status == HOST_NEW) {
604: host_file = system_hostfile;
1.108 markus 605: host_status = check_host_in_hostfile(host_file, host, host_key,
606: file_key, &host_line);
1.85 markus 607: }
1.40 markus 608: /*
609: * Also perform check for the ip address, skip the check if we are
610: * localhost or the hostname was an ip address to begin with
611: */
1.88 markus 612: if (options.check_host_ip) {
1.58 markus 613: Key *ip_key = key_new(host_key->type);
1.38 markus 614:
1.85 markus 615: ip_file = user_hostfile;
1.108 markus 616: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
617: ip_key, &ip_line);
1.85 markus 618: if (ip_status == HOST_NEW) {
619: ip_file = system_hostfile;
1.108 markus 620: ip_status = check_host_in_hostfile(ip_file, ip,
621: host_key, ip_key, &ip_line);
1.85 markus 622: }
1.38 markus 623: if (host_status == HOST_CHANGED &&
1.58 markus 624: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 625: host_ip_differ = 1;
626:
1.58 markus 627: key_free(ip_key);
1.38 markus 628: } else
629: ip_status = host_status;
630:
1.58 markus 631: key_free(file_key);
1.38 markus 632:
633: switch (host_status) {
634: case HOST_OK:
635: /* The host is known and the key matches. */
1.72 markus 636: debug("Host '%.200s' is known and matches the %s host key.",
637: host, type);
1.85 markus 638: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 639: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 640: if (readonly)
1.138 itojun 641: logit("%s host key for IP address "
1.108 markus 642: "'%.128s' not in list of known hosts.",
643: type, ip);
644: else if (!add_host_to_hostfile(user_hostfile, ip,
1.160 djm 645: host_key, options.hash_known_hosts))
1.138 itojun 646: logit("Failed to add the %s host key for IP "
1.108 markus 647: "address '%.128s' to the list of known "
648: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 649: else
1.138 itojun 650: logit("Warning: Permanently added the %s host "
1.108 markus 651: "key for IP address '%.128s' to the list "
652: "of known hosts.", type, ip);
1.38 markus 653: }
654: break;
655: case HOST_NEW:
1.108 markus 656: if (readonly)
657: goto fail;
1.38 markus 658: /* The host is new. */
659: if (options.strict_host_key_checking == 1) {
1.108 markus 660: /*
661: * User has requested strict host key checking. We
662: * will not add the host key automatically. The only
663: * alternative left is to abort.
664: */
665: error("No %s host key is known for %.200s and you "
666: "have requested strict checking.", type, host);
667: goto fail;
1.38 markus 668: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 669: char msg1[1024], msg2[1024];
670:
671: if (show_other_keys(host, host_key))
672: snprintf(msg1, sizeof(msg1),
1.168 djm 673: "\nbut keys of different type are already"
674: " known for this host.");
1.145 jakob 675: else
676: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 677: /* The default */
1.100 markus 678: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.145 jakob 679: msg2[0] = '\0';
680: if (options.verify_host_key_dns) {
1.153 jakob 681: if (matching_host_key_dns)
1.145 jakob 682: snprintf(msg2, sizeof(msg2),
683: "Matching host key fingerprint"
684: " found in DNS.\n");
685: else
686: snprintf(msg2, sizeof(msg2),
687: "No matching host key fingerprint"
688: " found in DNS.\n");
689: }
1.119 markus 690: snprintf(msg, sizeof(msg),
1.108 markus 691: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 692: "established%s\n"
1.145 jakob 693: "%s key fingerprint is %s.\n%s"
1.108 markus 694: "Are you sure you want to continue connecting "
1.132 markus 695: "(yes/no)? ",
1.145 jakob 696: host, ip, msg1, type, fp, msg2);
1.100 markus 697: xfree(fp);
1.119 markus 698: if (!confirm(msg))
1.108 markus 699: goto fail;
1.38 markus 700: }
1.161 djm 701: /*
702: * If not in strict mode, add the key automatically to the
703: * local known_hosts file.
704: */
1.88 markus 705: if (options.check_host_ip && ip_status == HOST_NEW) {
1.161 djm 706: snprintf(hostline, sizeof(hostline), "%s,%s",
707: host, ip);
1.38 markus 708: hostp = hostline;
1.161 djm 709: if (options.hash_known_hosts) {
710: /* Add hash of host and IP separately */
711: r = add_host_to_hostfile(user_hostfile, host,
712: host_key, options.hash_known_hosts) &&
713: add_host_to_hostfile(user_hostfile, ip,
714: host_key, options.hash_known_hosts);
715: } else {
716: /* Add unhashed "host,ip" */
717: r = add_host_to_hostfile(user_hostfile,
718: hostline, host_key,
719: options.hash_known_hosts);
720: }
721: } else {
722: r = add_host_to_hostfile(user_hostfile, host, host_key,
723: options.hash_known_hosts);
1.38 markus 724: hostp = host;
1.161 djm 725: }
1.38 markus 726:
1.161 djm 727: if (!r)
1.138 itojun 728: logit("Failed to add the host to the list of known "
1.108 markus 729: "hosts (%.500s).", user_hostfile);
1.38 markus 730: else
1.138 itojun 731: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 732: "list of known hosts.", hostp, type);
1.38 markus 733: break;
734: case HOST_CHANGED:
735: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 736: char *key_msg;
1.38 markus 737: if (ip_status == HOST_NEW)
1.158 avsm 738: key_msg = "is unknown";
1.38 markus 739: else if (ip_status == HOST_OK)
1.158 avsm 740: key_msg = "is unchanged";
1.38 markus 741: else
1.158 avsm 742: key_msg = "has a different value";
1.38 markus 743: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
744: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
745: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 746: error("The %s host key for %s has changed,", type, host);
1.38 markus 747: error("and the key for the according IP address %s", ip);
1.158 avsm 748: error("%s. This could either mean that", key_msg);
1.38 markus 749: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 750: error("and its host key have changed at the same time.");
1.88 markus 751: if (ip_status != HOST_NEW)
1.85 markus 752: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 753: }
754: /* The host key has changed. */
1.150 jakob 755: warn_changed_key(host_key);
1.38 markus 756: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 757: user_hostfile);
1.85 markus 758: error("Offending key in %s:%d", host_file, host_line);
1.38 markus 759:
1.40 markus 760: /*
761: * If strict host key checking is in use, the user will have
762: * to edit the key manually and we can only abort.
763: */
1.108 markus 764: if (options.strict_host_key_checking) {
765: error("%s host key for %.200s has changed and you have "
766: "requested strict checking.", type, host);
767: goto fail;
768: }
1.38 markus 769:
1.40 markus 770: /*
771: * If strict host key checking has not been requested, allow
1.144 djm 772: * the connection but without MITM-able authentication or
1.40 markus 773: * agent forwarding.
774: */
1.38 markus 775: if (options.password_authentication) {
1.108 markus 776: error("Password authentication is disabled to avoid "
777: "man-in-the-middle attacks.");
1.38 markus 778: options.password_authentication = 0;
1.144 djm 779: }
780: if (options.kbd_interactive_authentication) {
781: error("Keyboard-interactive authentication is disabled"
782: " to avoid man-in-the-middle attacks.");
783: options.kbd_interactive_authentication = 0;
784: options.challenge_response_authentication = 0;
785: }
786: if (options.challenge_response_authentication) {
787: error("Challenge/response authentication is disabled"
788: " to avoid man-in-the-middle attacks.");
789: options.challenge_response_authentication = 0;
1.38 markus 790: }
791: if (options.forward_agent) {
1.108 markus 792: error("Agent forwarding is disabled to avoid "
793: "man-in-the-middle attacks.");
1.38 markus 794: options.forward_agent = 0;
1.83 markus 795: }
796: if (options.forward_x11) {
1.108 markus 797: error("X11 forwarding is disabled to avoid "
798: "man-in-the-middle attacks.");
1.83 markus 799: options.forward_x11 = 0;
800: }
1.108 markus 801: if (options.num_local_forwards > 0 ||
802: options.num_remote_forwards > 0) {
803: error("Port forwarding is disabled to avoid "
804: "man-in-the-middle attacks.");
805: options.num_local_forwards =
1.118 deraadt 806: options.num_remote_forwards = 0;
1.38 markus 807: }
1.40 markus 808: /*
809: * XXX Should permit the user to change to use the new id.
810: * This could be done by converting the host key to an
811: * identifying sentence, tell that the host identifies itself
812: * by that sentence, and ask the user if he/she whishes to
813: * accept the authentication.
814: */
1.38 markus 815: break;
1.132 markus 816: case HOST_FOUND:
817: fatal("internal error");
818: break;
1.88 markus 819: }
820:
821: if (options.check_host_ip && host_status != HOST_CHANGED &&
822: ip_status == HOST_CHANGED) {
1.119 markus 823: snprintf(msg, sizeof(msg),
824: "Warning: the %s host key for '%.200s' "
825: "differs from the key for the IP address '%.128s'"
826: "\nOffending key for IP in %s:%d",
827: type, host, ip, ip_file, ip_line);
828: if (host_status == HOST_OK) {
829: len = strlen(msg);
830: snprintf(msg + len, sizeof(msg) - len,
831: "\nMatching host key in %s:%d",
1.125 deraadt 832: host_file, host_line);
1.119 markus 833: }
1.88 markus 834: if (options.strict_host_key_checking == 1) {
1.143 djm 835: logit("%s", msg);
1.108 markus 836: error("Exiting, you have requested strict checking.");
837: goto fail;
1.88 markus 838: } else if (options.strict_host_key_checking == 2) {
1.119 markus 839: strlcat(msg, "\nAre you sure you want "
840: "to continue connecting (yes/no)? ", sizeof(msg));
841: if (!confirm(msg))
1.108 markus 842: goto fail;
1.119 markus 843: } else {
1.143 djm 844: logit("%s", msg);
1.88 markus 845: }
1.38 markus 846: }
1.82 provos 847:
848: xfree(ip);
1.189 dtucker 849: xfree(host);
1.108 markus 850: return 0;
851:
852: fail:
853: xfree(ip);
1.189 dtucker 854: xfree(host);
1.108 markus 855: return -1;
856: }
857:
1.140 jakob 858: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 859: int
860: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
861: {
862: struct stat st;
1.153 jakob 863: int flags = 0;
1.140 jakob 864:
1.153 jakob 865: if (options.verify_host_key_dns &&
866: verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
867:
868: if (flags & DNS_VERIFY_FOUND) {
869:
870: if (options.verify_host_key_dns == 1 &&
871: flags & DNS_VERIFY_MATCH &&
872: flags & DNS_VERIFY_SECURE)
873: return 0;
874:
875: if (flags & DNS_VERIFY_MATCH) {
876: matching_host_key_dns = 1;
877: } else {
878: warn_changed_key(host_key);
879: error("Update the SSHFP RR in DNS with the new "
880: "host key to get rid of this message.");
881: }
1.140 jakob 882: }
883: }
1.108 markus 884:
885: /* return ok if the key can be found in an old keyfile */
886: if (stat(options.system_hostfile2, &st) == 0 ||
887: stat(options.user_hostfile2, &st) == 0) {
888: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
889: options.user_hostfile2, options.system_hostfile2) == 0)
890: return 0;
891: }
892: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
893: options.user_hostfile, options.system_hostfile);
1.51 markus 894: }
1.70 markus 895:
1.51 markus 896: /*
897: * Starts a dialog with the server, and authenticates the current user on the
898: * server. This does not need any extra privileges. The basic connection
899: * to the server must already have been established before this is called.
900: * If login fails, this function prints an error and never returns.
901: * This function does not require super-user privileges.
902: */
903: void
1.120 markus 904: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 905: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 906: {
907: char *host, *cp;
1.70 markus 908: char *server_user, *local_user;
909:
910: local_user = xstrdup(pw->pw_name);
911: server_user = options.user ? options.user : local_user;
1.51 markus 912:
913: /* Convert the user-supplied hostname into all lowercase. */
914: host = xstrdup(orighost);
915: for (cp = host; *cp; cp++)
916: if (isupper(*cp))
1.178 deraadt 917: *cp = (char)tolower(*cp);
1.51 markus 918:
919: /* Exchange protocol version identification strings with the server. */
920: ssh_exchange_identification();
921:
922: /* Put the connection into non-blocking mode. */
923: packet_set_nonblocking();
924:
925: /* key exchange */
926: /* authenticate user */
1.59 markus 927: if (compat20) {
928: ssh_kex2(host, hostaddr);
1.120 markus 929: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 930: } else {
931: ssh_kex(host, hostaddr);
1.120 markus 932: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 933: }
1.182 markus 934: xfree(local_user);
1.97 markus 935: }
936:
937: void
938: ssh_put_password(char *password)
939: {
940: int size;
941: char *padded;
942:
1.99 deraadt 943: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 944: packet_put_cstring(password);
1.99 deraadt 945: return;
946: }
1.97 markus 947: size = roundup(strlen(password) + 1, 32);
1.179 djm 948: padded = xcalloc(1, size);
1.97 markus 949: strlcpy(padded, password, size);
950: packet_put_string(padded, size);
951: memset(padded, 0, size);
952: xfree(padded);
1.132 markus 953: }
954:
955: static int
956: show_key_from_file(const char *file, const char *host, int keytype)
957: {
958: Key *found;
959: char *fp;
960: int line, ret;
961:
962: found = key_new(keytype);
963: if ((ret = lookup_key_in_hostfile_by_type(file, host,
964: keytype, found, &line))) {
965: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 966: logit("WARNING: %s key found for host %s\n"
1.133 markus 967: "in %s:%d\n"
1.132 markus 968: "%s key fingerprint %s.",
969: key_type(found), host, file, line,
970: key_type(found), fp);
971: xfree(fp);
972: }
973: key_free(found);
974: return (ret);
975: }
976:
977: /* print all known host keys for a given host, but skip keys of given type */
978: static int
979: show_other_keys(const char *host, Key *key)
980: {
981: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
982: int i, found = 0;
983:
984: for (i = 0; type[i] != -1; i++) {
985: if (type[i] == key->type)
986: continue;
987: if (type[i] != KEY_RSA1 &&
988: show_key_from_file(options.user_hostfile2, host, type[i])) {
989: found = 1;
990: continue;
991: }
992: if (type[i] != KEY_RSA1 &&
993: show_key_from_file(options.system_hostfile2, host, type[i])) {
994: found = 1;
995: continue;
996: }
997: if (show_key_from_file(options.user_hostfile, host, type[i])) {
998: found = 1;
999: continue;
1000: }
1001: if (show_key_from_file(options.system_hostfile, host, type[i])) {
1002: found = 1;
1003: continue;
1004: }
1005: debug2("no key of type %d for host %s", type[i], host);
1006: }
1007: return (found);
1.150 jakob 1008: }
1009:
1010: static void
1011: warn_changed_key(Key *host_key)
1012: {
1013: char *fp;
1.151 jakob 1014: const char *type = key_type(host_key);
1.150 jakob 1015:
1016: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1017:
1018: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1019: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1020: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1021: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1022: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1023: error("It is also possible that the %s host key has just been changed.", type);
1024: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1025: type, fp);
1026: error("Please contact your system administrator.");
1027:
1028: xfree(fp);
1.171 reyk 1029: }
1030:
1031: /*
1032: * Execute a local command
1033: */
1034: int
1035: ssh_local_cmd(const char *args)
1036: {
1037: char *shell;
1038: pid_t pid;
1039: int status;
1040:
1041: if (!options.permit_local_command ||
1042: args == NULL || !*args)
1043: return (1);
1044:
1045: if ((shell = getenv("SHELL")) == NULL)
1046: shell = _PATH_BSHELL;
1047:
1048: pid = fork();
1049: if (pid == 0) {
1050: debug3("Executing %s -c \"%s\"", shell, args);
1051: execl(shell, shell, "-c", args, (char *)NULL);
1052: error("Couldn't execute %s -c \"%s\": %s",
1053: shell, args, strerror(errno));
1054: _exit(1);
1055: } else if (pid == -1)
1056: fatal("fork failed: %.100s", strerror(errno));
1057: while (waitpid(pid, &status, 0) == -1)
1058: if (errno != EINTR)
1059: fatal("Couldn't wait for child: %s", strerror(errno));
1060:
1061: if (!WIFEXITED(status))
1062: return (1);
1063:
1064: return (WEXITSTATUS(status));
1.1 deraadt 1065: }
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