Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.174
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"
1.174 ! stevesk 16: RCSID("$OpenBSD: sshconnect.c,v 1.173 2006/02/08 14:16:59 stevesk Exp $");
! 17:
! 18: #include <sys/types.h>
! 19: #include <sys/wait.h>
1.172 stevesk 20:
21: #include <paths.h>
1.71 markus 22:
1.91 markus 23: #include "ssh.h"
1.1 deraadt 24: #include "xmalloc.h"
25: #include "rsa.h"
1.59 markus 26: #include "buffer.h"
1.1 deraadt 27: #include "packet.h"
28: #include "uidswap.h"
1.21 markus 29: #include "compat.h"
1.58 markus 30: #include "key.h"
1.71 markus 31: #include "sshconnect.h"
1.58 markus 32: #include "hostfile.h"
1.91 markus 33: #include "log.h"
34: #include "readconf.h"
35: #include "atomicio.h"
36: #include "misc.h"
1.140 jakob 37: #include "dns.h"
38:
1.70 markus 39: char *client_version_string = NULL;
40: char *server_version_string = NULL;
1.59 markus 41:
1.169 stevesk 42: static int matching_host_key_dns = 0;
1.145 jakob 43:
1.124 markus 44: /* import */
1.43 markus 45: extern Options options;
1.50 markus 46: extern char *__progname;
1.124 markus 47: extern uid_t original_real_uid;
48: extern uid_t original_effective_uid;
1.135 djm 49: extern pid_t proxy_command_pid;
1.91 markus 50:
1.132 markus 51: static int show_other_keys(const char *, Key *);
1.150 jakob 52: static void warn_changed_key(Key *);
1.132 markus 53:
1.39 deraadt 54: /*
55: * Connect to the given ssh server using a proxy command.
56: */
1.109 itojun 57: static int
1.124 markus 58: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 59: {
1.164 djm 60: char *command_string, *tmp;
1.38 markus 61: int pin[2], pout[2];
1.69 deraadt 62: pid_t pid;
1.49 markus 63: char strport[NI_MAXSERV];
1.164 djm 64: size_t len;
1.38 markus 65:
66: /* Convert the port number into a string. */
1.49 markus 67: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 68:
1.135 djm 69: /*
70: * Build the final command string in the buffer by making the
71: * appropriate substitutions to the given proxy command.
72: *
1.154 djm 73: * Use "exec" to avoid "sh -c" processes on some platforms
1.135 djm 74: * (e.g. Solaris)
75: */
1.164 djm 76: len = strlen(proxy_command) + 6;
77: tmp = xmalloc(len);
78: strlcpy(tmp, "exec ", len);
79: strlcat(tmp, proxy_command, len);
80: command_string = percent_expand(tmp, "h", host,
81: "p", strport, (char *)NULL);
82: xfree(tmp);
1.38 markus 83:
84: /* Create pipes for communicating with the proxy. */
85: if (pipe(pin) < 0 || pipe(pout) < 0)
86: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 87: strerror(errno));
1.38 markus 88:
89: debug("Executing proxy command: %.500s", command_string);
90:
91: /* Fork and execute the proxy command. */
92: if ((pid = fork()) == 0) {
93: char *argv[10];
94:
95: /* Child. Permanently give up superuser privileges. */
1.124 markus 96: seteuid(original_real_uid);
97: setuid(original_real_uid);
1.38 markus 98:
99: /* Redirect stdin and stdout. */
100: close(pin[1]);
101: if (pin[0] != 0) {
102: if (dup2(pin[0], 0) < 0)
103: perror("dup2 stdin");
104: close(pin[0]);
105: }
106: close(pout[0]);
107: if (dup2(pout[1], 1) < 0)
108: perror("dup2 stdout");
109: /* Cannot be 1 because pin allocated two descriptors. */
110: close(pout[1]);
111:
112: /* Stderr is left as it is so that error messages get
113: printed on the user's terminal. */
1.89 markus 114: argv[0] = _PATH_BSHELL;
1.38 markus 115: argv[1] = "-c";
116: argv[2] = command_string;
117: argv[3] = NULL;
118:
119: /* Execute the proxy command. Note that we gave up any
120: extra privileges above. */
1.89 markus 121: execv(argv[0], argv);
122: perror(argv[0]);
1.38 markus 123: exit(1);
124: }
125: /* Parent. */
126: if (pid < 0)
127: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 128: else
129: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 130:
131: /* Close child side of the descriptors. */
132: close(pin[0]);
133: close(pout[1]);
134:
135: /* Free the command name. */
1.164 djm 136: xfree(command_string);
1.38 markus 137:
138: /* Set the connection file descriptors. */
139: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 140:
1.110 markus 141: /* Indicate OK return */
142: return 0;
1.1 deraadt 143: }
144:
1.39 deraadt 145: /*
146: * Creates a (possibly privileged) socket for use as the ssh connection.
147: */
1.109 itojun 148: static int
1.139 markus 149: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 150: {
1.105 markus 151: int sock, gaierr;
152: struct addrinfo hints, *res;
1.1 deraadt 153:
1.40 markus 154: /*
155: * If we are running as root and want to connect to a privileged
156: * port, bind our own socket to a privileged port.
157: */
1.38 markus 158: if (privileged) {
159: int p = IPPORT_RESERVED - 1;
1.124 markus 160: PRIV_START;
1.139 markus 161: sock = rresvport_af(&p, ai->ai_family);
1.124 markus 162: PRIV_END;
1.38 markus 163: if (sock < 0)
1.139 markus 164: error("rresvport: af=%d %.100s", ai->ai_family,
165: strerror(errno));
1.55 markus 166: else
167: debug("Allocated local port %d.", p);
1.105 markus 168: return sock;
169: }
1.139 markus 170: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.105 markus 171: if (sock < 0)
172: error("socket: %.100s", strerror(errno));
173:
174: /* Bind the socket to an alternative local IP address */
175: if (options.bind_address == NULL)
176: return sock;
177:
178: memset(&hints, 0, sizeof(hints));
1.139 markus 179: hints.ai_family = ai->ai_family;
180: hints.ai_socktype = ai->ai_socktype;
181: hints.ai_protocol = ai->ai_protocol;
1.105 markus 182: hints.ai_flags = AI_PASSIVE;
183: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
184: if (gaierr) {
185: error("getaddrinfo: %s: %s", options.bind_address,
186: gai_strerror(gaierr));
187: close(sock);
188: return -1;
189: }
190: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
191: error("bind: %s: %s", options.bind_address, strerror(errno));
192: close(sock);
193: freeaddrinfo(res);
194: return -1;
1.38 markus 195: }
1.105 markus 196: freeaddrinfo(res);
1.38 markus 197: return sock;
1.1 deraadt 198: }
199:
1.141 djm 200: static int
201: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
202: socklen_t addrlen, int timeout)
203: {
204: fd_set *fdset;
205: struct timeval tv;
206: socklen_t optlen;
1.142 djm 207: int fdsetsz, optval, rc, result = -1;
1.141 djm 208:
209: if (timeout <= 0)
210: return (connect(sockfd, serv_addr, addrlen));
211:
1.156 djm 212: set_nonblock(sockfd);
1.141 djm 213: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 214: if (rc == 0) {
215: unset_nonblock(sockfd);
1.141 djm 216: return (0);
1.156 djm 217: }
1.141 djm 218: if (errno != EINPROGRESS)
219: return (-1);
220:
221: fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask);
222: fdset = (fd_set *)xmalloc(fdsetsz);
223:
1.147 markus 224: memset(fdset, 0, fdsetsz);
1.141 djm 225: FD_SET(sockfd, fdset);
226: tv.tv_sec = timeout;
227: tv.tv_usec = 0;
228:
1.162 deraadt 229: for (;;) {
1.141 djm 230: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
231: if (rc != -1 || errno != EINTR)
232: break;
233: }
234:
1.162 deraadt 235: switch (rc) {
1.141 djm 236: case 0:
237: /* Timed out */
238: errno = ETIMEDOUT;
1.142 djm 239: break;
1.141 djm 240: case -1:
241: /* Select error */
1.154 djm 242: debug("select: %s", strerror(errno));
1.142 djm 243: break;
1.141 djm 244: case 1:
245: /* Completed or failed */
246: optval = 0;
247: optlen = sizeof(optval);
1.154 djm 248: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 249: &optlen) == -1) {
1.154 djm 250: debug("getsockopt: %s", strerror(errno));
1.142 djm 251: break;
1.148 markus 252: }
1.141 djm 253: if (optval != 0) {
254: errno = optval;
1.142 djm 255: break;
1.141 djm 256: }
1.142 djm 257: result = 0;
1.156 djm 258: unset_nonblock(sockfd);
1.141 djm 259: break;
260: default:
261: /* Should not occur */
262: fatal("Bogus return (%d) from select()", rc);
263: }
264:
1.142 djm 265: xfree(fdset);
266: return (result);
1.141 djm 267: }
268:
1.39 deraadt 269: /*
1.49 markus 270: * Opens a TCP/IP connection to the remote server on the given host.
271: * The address of the remote host will be returned in hostaddr.
1.124 markus 272: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 273: * a privileged port will be allocated to make the connection.
1.124 markus 274: * This requires super-user privileges if needpriv is true.
1.39 deraadt 275: * Connection_attempts specifies the maximum number of tries (one per
276: * second). If proxy_command is non-NULL, it specifies the command (with %h
277: * and %p substituted for host and port, respectively) to use to contact
278: * the daemon.
279: */
1.38 markus 280: int
1.49 markus 281: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 282: u_short port, int family, int connection_attempts,
1.124 markus 283: int needpriv, const char *proxy_command)
1.1 deraadt 284: {
1.90 markus 285: int gaierr;
286: int on = 1;
1.49 markus 287: int sock = -1, attempt;
1.90 markus 288: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 289: struct addrinfo hints, *ai, *aitop;
1.38 markus 290:
1.136 markus 291: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 292:
293: /* If a proxy command is given, connect using it. */
294: if (proxy_command != NULL)
1.124 markus 295: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 296:
297: /* No proxy command. */
298:
1.49 markus 299: memset(&hints, 0, sizeof(hints));
1.115 markus 300: hints.ai_family = family;
1.49 markus 301: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 302: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 303: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 304: fatal("%s: %.100s: %s", __progname, host,
305: gai_strerror(gaierr));
1.38 markus 306:
1.46 markus 307: /*
308: * Try to connect several times. On some machines, the first time
309: * will sometimes fail. In general socket code appears to behave
310: * quite magically on many machines.
1.110 markus 311: */
312: for (attempt = 0; ;) {
1.38 markus 313: if (attempt > 0)
314: debug("Trying again...");
315:
1.49 markus 316: /* Loop through addresses for this host, and try each one in
1.68 markus 317: sequence until the connection succeeds. */
1.49 markus 318: for (ai = aitop; ai; ai = ai->ai_next) {
319: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
320: continue;
321: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
322: ntop, sizeof(ntop), strport, sizeof(strport),
323: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
324: error("ssh_connect: getnameinfo failed");
325: continue;
326: }
327: debug("Connecting to %.200s [%.100s] port %s.",
328: host, ntop, strport);
329:
330: /* Create a socket for connecting. */
1.139 markus 331: sock = ssh_create_socket(needpriv, ai);
1.49 markus 332: if (sock < 0)
1.110 markus 333: /* Any error is already output */
1.49 markus 334: continue;
335:
1.141 djm 336: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
337: options.connection_timeout) >= 0) {
1.49 markus 338: /* Successful connection. */
1.102 markus 339: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 340: break;
1.49 markus 341: } else {
1.131 itojun 342: debug("connect to address %s port %s: %s",
343: ntop, strport, strerror(errno));
1.40 markus 344: /*
345: * Close the failed socket; there appear to
346: * be some problems when reusing a socket for
347: * which connect() has already returned an
348: * error.
349: */
1.38 markus 350: close(sock);
351: }
352: }
1.49 markus 353: if (ai)
354: break; /* Successful connection. */
1.1 deraadt 355:
1.110 markus 356: attempt++;
357: if (attempt >= connection_attempts)
358: break;
1.38 markus 359: /* Sleep a moment before retrying. */
360: sleep(1);
361: }
1.49 markus 362:
363: freeaddrinfo(aitop);
364:
1.38 markus 365: /* Return failure if we didn't get a successful connection. */
1.130 itojun 366: if (attempt >= connection_attempts) {
1.159 markus 367: error("ssh: connect to host %s port %s: %s",
1.130 itojun 368: host, strport, strerror(errno));
1.159 markus 369: return (-1);
1.130 itojun 370: }
1.38 markus 371:
372: debug("Connection established.");
1.90 markus 373:
1.155 markus 374: /* Set SO_KEEPALIVE if requested. */
375: if (options.tcp_keep_alive &&
1.90 markus 376: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
377: sizeof(on)) < 0)
378: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 379:
380: /* Set the connection. */
381: packet_set_connection(sock, sock);
1.1 deraadt 382:
1.110 markus 383: return 0;
1.59 markus 384: }
385:
1.43 markus 386: /*
1.39 deraadt 387: * Waits for the server identification string, and sends our own
388: * identification string.
389: */
1.109 itojun 390: static void
1.95 itojun 391: ssh_exchange_identification(void)
1.1 deraadt 392: {
1.38 markus 393: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 394: int remote_major, remote_minor, mismatch;
1.38 markus 395: int connection_in = packet_get_connection_in();
396: int connection_out = packet_get_connection_out();
1.93 stevesk 397: int minor1 = PROTOCOL_MINOR_1;
1.165 djm 398: u_int i;
1.38 markus 399:
1.163 avsm 400: /* Read other side's version identification. */
1.75 markus 401: for (;;) {
402: for (i = 0; i < sizeof(buf) - 1; i++) {
1.163 avsm 403: size_t len = atomicio(read, connection_in, &buf[i], 1);
404:
1.167 djm 405: if (len != 1 && errno == EPIPE)
1.163 avsm 406: fatal("ssh_exchange_identification: Connection closed by remote host");
407: else if (len != 1)
1.75 markus 408: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
409: if (buf[i] == '\r') {
410: buf[i] = '\n';
411: buf[i + 1] = 0;
412: continue; /**XXX wait for \n */
413: }
414: if (buf[i] == '\n') {
415: buf[i + 1] = 0;
416: break;
417: }
1.38 markus 418: }
1.75 markus 419: buf[sizeof(buf) - 1] = 0;
1.76 markus 420: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 421: break;
1.75 markus 422: debug("ssh_exchange_identification: %s", buf);
1.38 markus 423: }
1.59 markus 424: server_version_string = xstrdup(buf);
1.38 markus 425:
1.40 markus 426: /*
427: * Check that the versions match. In future this might accept
428: * several versions and set appropriate flags to handle them.
429: */
1.59 markus 430: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
431: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 432: fatal("Bad remote protocol version identification: '%.100s'", buf);
433: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 434: remote_major, remote_minor, remote_version);
1.38 markus 435:
1.59 markus 436: compat_datafellows(remote_version);
1.64 markus 437: mismatch = 0;
1.59 markus 438:
1.116 deraadt 439: switch (remote_major) {
1.64 markus 440: case 1:
441: if (remote_minor == 99 &&
442: (options.protocol & SSH_PROTO_2) &&
443: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
444: enable_compat20();
445: break;
446: }
447: if (!(options.protocol & SSH_PROTO_1)) {
448: mismatch = 1;
449: break;
450: }
451: if (remote_minor < 3) {
452: fatal("Remote machine has too old SSH software version.");
1.81 markus 453: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 454: /* We speak 1.3, too. */
455: enable_compat13();
1.81 markus 456: minor1 = 3;
1.64 markus 457: if (options.forward_agent) {
1.138 itojun 458: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 459: options.forward_agent = 0;
460: }
461: }
462: break;
463: case 2:
464: if (options.protocol & SSH_PROTO_2) {
465: enable_compat20();
466: break;
1.38 markus 467: }
1.64 markus 468: /* FALLTHROUGH */
1.68 markus 469: default:
1.64 markus 470: mismatch = 1;
471: break;
1.38 markus 472: }
1.64 markus 473: if (mismatch)
1.38 markus 474: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 475: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
476: remote_major);
1.38 markus 477: /* Send our own protocol version identification. */
478: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 479: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 480: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 481: SSH_VERSION);
1.146 deraadt 482: if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 483: fatal("write: %.100s", strerror(errno));
1.59 markus 484: client_version_string = xstrdup(buf);
485: chop(client_version_string);
486: chop(server_version_string);
487: debug("Local version string %.100s", client_version_string);
1.1 deraadt 488: }
489:
1.96 markus 490: /* defaults to 'no' */
1.109 itojun 491: static int
1.112 markus 492: confirm(const char *prompt)
1.1 deraadt 493: {
1.119 markus 494: const char *msg, *again = "Please type 'yes' or 'no': ";
495: char *p;
496: int ret = -1;
1.96 markus 497:
498: if (options.batch_mode)
499: return 0;
1.119 markus 500: for (msg = prompt;;msg = again) {
501: p = read_passphrase(msg, RP_ECHO);
502: if (p == NULL ||
503: (p[0] == '\0') || (p[0] == '\n') ||
504: strncasecmp(p, "no", 2) == 0)
505: ret = 0;
1.127 markus 506: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 507: ret = 1;
508: if (p)
509: xfree(p);
510: if (ret != -1)
511: return ret;
1.1 deraadt 512: }
513: }
514:
1.39 deraadt 515: /*
1.108 markus 516: * check whether the supplied host key is valid, return -1 if the key
517: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 518: */
1.109 itojun 519: static int
1.70 markus 520: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 521: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 522: {
1.58 markus 523: Key *file_key;
1.152 jakob 524: const char *type = key_type(host_key);
1.46 markus 525: char *ip = NULL;
1.100 markus 526: char hostline[1000], *hostp, *fp;
1.38 markus 527: HostStatus host_status;
528: HostStatus ip_status;
1.161 djm 529: int r, local = 0, host_ip_differ = 0;
1.49 markus 530: char ntop[NI_MAXHOST];
1.119 markus 531: char msg[1024];
1.145 jakob 532: int len, host_line, ip_line;
1.85 markus 533: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 534:
535: /*
536: * Force accepting of the host key for loopback/localhost. The
537: * problem is that if the home directory is NFS-mounted to multiple
538: * machines, localhost will refer to a different machine in each of
539: * them, and the user will get bogus HOST_CHANGED warnings. This
540: * essentially disables host authentication for localhost; however,
541: * this is probably not a real problem.
542: */
1.70 markus 543: /** hostaddr == 0! */
1.49 markus 544: switch (hostaddr->sa_family) {
545: case AF_INET:
1.108 markus 546: local = (ntohl(((struct sockaddr_in *)hostaddr)->
1.168 djm 547: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 548: break;
549: case AF_INET6:
1.108 markus 550: local = IN6_IS_ADDR_LOOPBACK(
551: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 552: break;
553: default:
554: local = 0;
555: break;
556: }
1.111 markus 557: if (options.no_host_authentication_for_localhost == 1 && local &&
558: options.host_key_alias == NULL) {
1.88 markus 559: debug("Forcing accepting of host key for "
560: "loopback/localhost.");
1.108 markus 561: return 0;
1.49 markus 562: }
1.42 markus 563:
564: /*
1.88 markus 565: * We don't have the remote ip-address for connections
566: * using a proxy command
1.42 markus 567: */
1.84 markus 568: if (options.proxy_command == NULL) {
569: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 570: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 571: fatal("check_host_key: getnameinfo failed");
572: ip = xstrdup(ntop);
573: } else {
574: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 575: }
1.88 markus 576: /*
577: * Turn off check_host_ip if the connection is to localhost, via proxy
578: * command or if we don't have a hostname to compare with
579: */
580: if (options.check_host_ip &&
581: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
582: options.check_host_ip = 0;
1.86 markus 583:
584: /*
585: * Allow the user to record the key under a different name. This is
586: * useful for ssh tunneling over forwarded connections or if you run
587: * multiple sshd's on different ports on the same machine.
588: */
589: if (options.host_key_alias != NULL) {
590: host = options.host_key_alias;
591: debug("using hostkeyalias: %s", host);
1.84 markus 592: }
1.38 markus 593:
1.46 markus 594: /*
595: * Store the host key from the known host file in here so that we can
596: * compare it with the key for the IP address.
597: */
1.58 markus 598: file_key = key_new(host_key->type);
1.38 markus 599:
1.40 markus 600: /*
1.170 djm 601: * Check if the host key is present in the user's list of known
1.40 markus 602: * hosts or in the systemwide list.
603: */
1.85 markus 604: host_file = user_hostfile;
1.108 markus 605: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 606: file_key, &host_line);
1.85 markus 607: if (host_status == HOST_NEW) {
608: host_file = system_hostfile;
1.108 markus 609: host_status = check_host_in_hostfile(host_file, host, host_key,
610: file_key, &host_line);
1.85 markus 611: }
1.40 markus 612: /*
613: * Also perform check for the ip address, skip the check if we are
614: * localhost or the hostname was an ip address to begin with
615: */
1.88 markus 616: if (options.check_host_ip) {
1.58 markus 617: Key *ip_key = key_new(host_key->type);
1.38 markus 618:
1.85 markus 619: ip_file = user_hostfile;
1.108 markus 620: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
621: ip_key, &ip_line);
1.85 markus 622: if (ip_status == HOST_NEW) {
623: ip_file = system_hostfile;
1.108 markus 624: ip_status = check_host_in_hostfile(ip_file, ip,
625: host_key, ip_key, &ip_line);
1.85 markus 626: }
1.38 markus 627: if (host_status == HOST_CHANGED &&
1.58 markus 628: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 629: host_ip_differ = 1;
630:
1.58 markus 631: key_free(ip_key);
1.38 markus 632: } else
633: ip_status = host_status;
634:
1.58 markus 635: key_free(file_key);
1.38 markus 636:
637: switch (host_status) {
638: case HOST_OK:
639: /* The host is known and the key matches. */
1.72 markus 640: debug("Host '%.200s' is known and matches the %s host key.",
641: host, type);
1.85 markus 642: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 643: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 644: if (readonly)
1.138 itojun 645: logit("%s host key for IP address "
1.108 markus 646: "'%.128s' not in list of known hosts.",
647: type, ip);
648: else if (!add_host_to_hostfile(user_hostfile, ip,
1.160 djm 649: host_key, options.hash_known_hosts))
1.138 itojun 650: logit("Failed to add the %s host key for IP "
1.108 markus 651: "address '%.128s' to the list of known "
652: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 653: else
1.138 itojun 654: logit("Warning: Permanently added the %s host "
1.108 markus 655: "key for IP address '%.128s' to the list "
656: "of known hosts.", type, ip);
1.38 markus 657: }
658: break;
659: case HOST_NEW:
1.108 markus 660: if (readonly)
661: goto fail;
1.38 markus 662: /* The host is new. */
663: if (options.strict_host_key_checking == 1) {
1.108 markus 664: /*
665: * User has requested strict host key checking. We
666: * will not add the host key automatically. The only
667: * alternative left is to abort.
668: */
669: error("No %s host key is known for %.200s and you "
670: "have requested strict checking.", type, host);
671: goto fail;
1.38 markus 672: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 673: char msg1[1024], msg2[1024];
674:
675: if (show_other_keys(host, host_key))
676: snprintf(msg1, sizeof(msg1),
1.168 djm 677: "\nbut keys of different type are already"
678: " known for this host.");
1.145 jakob 679: else
680: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 681: /* The default */
1.100 markus 682: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.145 jakob 683: msg2[0] = '\0';
684: if (options.verify_host_key_dns) {
1.153 jakob 685: if (matching_host_key_dns)
1.145 jakob 686: snprintf(msg2, sizeof(msg2),
687: "Matching host key fingerprint"
688: " found in DNS.\n");
689: else
690: snprintf(msg2, sizeof(msg2),
691: "No matching host key fingerprint"
692: " found in DNS.\n");
693: }
1.119 markus 694: snprintf(msg, sizeof(msg),
1.108 markus 695: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 696: "established%s\n"
1.145 jakob 697: "%s key fingerprint is %s.\n%s"
1.108 markus 698: "Are you sure you want to continue connecting "
1.132 markus 699: "(yes/no)? ",
1.145 jakob 700: host, ip, msg1, type, fp, msg2);
1.100 markus 701: xfree(fp);
1.119 markus 702: if (!confirm(msg))
1.108 markus 703: goto fail;
1.38 markus 704: }
1.161 djm 705: /*
706: * If not in strict mode, add the key automatically to the
707: * local known_hosts file.
708: */
1.88 markus 709: if (options.check_host_ip && ip_status == HOST_NEW) {
1.161 djm 710: snprintf(hostline, sizeof(hostline), "%s,%s",
711: host, ip);
1.38 markus 712: hostp = hostline;
1.161 djm 713: if (options.hash_known_hosts) {
714: /* Add hash of host and IP separately */
715: r = add_host_to_hostfile(user_hostfile, host,
716: host_key, options.hash_known_hosts) &&
717: add_host_to_hostfile(user_hostfile, ip,
718: host_key, options.hash_known_hosts);
719: } else {
720: /* Add unhashed "host,ip" */
721: r = add_host_to_hostfile(user_hostfile,
722: hostline, host_key,
723: options.hash_known_hosts);
724: }
725: } else {
726: r = add_host_to_hostfile(user_hostfile, host, host_key,
727: options.hash_known_hosts);
1.38 markus 728: hostp = host;
1.161 djm 729: }
1.38 markus 730:
1.161 djm 731: if (!r)
1.138 itojun 732: logit("Failed to add the host to the list of known "
1.108 markus 733: "hosts (%.500s).", user_hostfile);
1.38 markus 734: else
1.138 itojun 735: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 736: "list of known hosts.", hostp, type);
1.38 markus 737: break;
738: case HOST_CHANGED:
739: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 740: char *key_msg;
1.38 markus 741: if (ip_status == HOST_NEW)
1.158 avsm 742: key_msg = "is unknown";
1.38 markus 743: else if (ip_status == HOST_OK)
1.158 avsm 744: key_msg = "is unchanged";
1.38 markus 745: else
1.158 avsm 746: key_msg = "has a different value";
1.38 markus 747: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
748: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
749: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 750: error("The %s host key for %s has changed,", type, host);
1.38 markus 751: error("and the key for the according IP address %s", ip);
1.158 avsm 752: error("%s. This could either mean that", key_msg);
1.38 markus 753: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 754: error("and its host key have changed at the same time.");
1.88 markus 755: if (ip_status != HOST_NEW)
1.85 markus 756: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 757: }
758: /* The host key has changed. */
1.150 jakob 759: warn_changed_key(host_key);
1.38 markus 760: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 761: user_hostfile);
1.85 markus 762: error("Offending key in %s:%d", host_file, host_line);
1.38 markus 763:
1.40 markus 764: /*
765: * If strict host key checking is in use, the user will have
766: * to edit the key manually and we can only abort.
767: */
1.108 markus 768: if (options.strict_host_key_checking) {
769: error("%s host key for %.200s has changed and you have "
770: "requested strict checking.", type, host);
771: goto fail;
772: }
1.38 markus 773:
1.40 markus 774: /*
775: * If strict host key checking has not been requested, allow
1.144 djm 776: * the connection but without MITM-able authentication or
1.40 markus 777: * agent forwarding.
778: */
1.38 markus 779: if (options.password_authentication) {
1.108 markus 780: error("Password authentication is disabled to avoid "
781: "man-in-the-middle attacks.");
1.38 markus 782: options.password_authentication = 0;
1.144 djm 783: }
784: if (options.kbd_interactive_authentication) {
785: error("Keyboard-interactive authentication is disabled"
786: " to avoid man-in-the-middle attacks.");
787: options.kbd_interactive_authentication = 0;
788: options.challenge_response_authentication = 0;
789: }
790: if (options.challenge_response_authentication) {
791: error("Challenge/response authentication is disabled"
792: " to avoid man-in-the-middle attacks.");
793: options.challenge_response_authentication = 0;
1.38 markus 794: }
795: if (options.forward_agent) {
1.108 markus 796: error("Agent forwarding is disabled to avoid "
797: "man-in-the-middle attacks.");
1.38 markus 798: options.forward_agent = 0;
1.83 markus 799: }
800: if (options.forward_x11) {
1.108 markus 801: error("X11 forwarding is disabled to avoid "
802: "man-in-the-middle attacks.");
1.83 markus 803: options.forward_x11 = 0;
804: }
1.108 markus 805: if (options.num_local_forwards > 0 ||
806: options.num_remote_forwards > 0) {
807: error("Port forwarding is disabled to avoid "
808: "man-in-the-middle attacks.");
809: options.num_local_forwards =
1.118 deraadt 810: options.num_remote_forwards = 0;
1.38 markus 811: }
1.40 markus 812: /*
813: * XXX Should permit the user to change to use the new id.
814: * This could be done by converting the host key to an
815: * identifying sentence, tell that the host identifies itself
816: * by that sentence, and ask the user if he/she whishes to
817: * accept the authentication.
818: */
1.38 markus 819: break;
1.132 markus 820: case HOST_FOUND:
821: fatal("internal error");
822: break;
1.88 markus 823: }
824:
825: if (options.check_host_ip && host_status != HOST_CHANGED &&
826: ip_status == HOST_CHANGED) {
1.119 markus 827: snprintf(msg, sizeof(msg),
828: "Warning: the %s host key for '%.200s' "
829: "differs from the key for the IP address '%.128s'"
830: "\nOffending key for IP in %s:%d",
831: type, host, ip, ip_file, ip_line);
832: if (host_status == HOST_OK) {
833: len = strlen(msg);
834: snprintf(msg + len, sizeof(msg) - len,
835: "\nMatching host key in %s:%d",
1.125 deraadt 836: host_file, host_line);
1.119 markus 837: }
1.88 markus 838: if (options.strict_host_key_checking == 1) {
1.143 djm 839: logit("%s", msg);
1.108 markus 840: error("Exiting, you have requested strict checking.");
841: goto fail;
1.88 markus 842: } else if (options.strict_host_key_checking == 2) {
1.119 markus 843: strlcat(msg, "\nAre you sure you want "
844: "to continue connecting (yes/no)? ", sizeof(msg));
845: if (!confirm(msg))
1.108 markus 846: goto fail;
1.119 markus 847: } else {
1.143 djm 848: logit("%s", msg);
1.88 markus 849: }
1.38 markus 850: }
1.82 provos 851:
852: xfree(ip);
1.108 markus 853: return 0;
854:
855: fail:
856: xfree(ip);
857: return -1;
858: }
859:
1.140 jakob 860: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 861: int
862: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
863: {
864: struct stat st;
1.153 jakob 865: int flags = 0;
1.140 jakob 866:
1.153 jakob 867: if (options.verify_host_key_dns &&
868: verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
869:
870: if (flags & DNS_VERIFY_FOUND) {
871:
872: if (options.verify_host_key_dns == 1 &&
873: flags & DNS_VERIFY_MATCH &&
874: flags & DNS_VERIFY_SECURE)
875: return 0;
876:
877: if (flags & DNS_VERIFY_MATCH) {
878: matching_host_key_dns = 1;
879: } else {
880: warn_changed_key(host_key);
881: error("Update the SSHFP RR in DNS with the new "
882: "host key to get rid of this message.");
883: }
1.140 jakob 884: }
885: }
1.108 markus 886:
887: /* return ok if the key can be found in an old keyfile */
888: if (stat(options.system_hostfile2, &st) == 0 ||
889: stat(options.user_hostfile2, &st) == 0) {
890: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
891: options.user_hostfile2, options.system_hostfile2) == 0)
892: return 0;
893: }
894: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
895: options.user_hostfile, options.system_hostfile);
1.51 markus 896: }
1.70 markus 897:
1.51 markus 898: /*
899: * Starts a dialog with the server, and authenticates the current user on the
900: * server. This does not need any extra privileges. The basic connection
901: * to the server must already have been established before this is called.
902: * If login fails, this function prints an error and never returns.
903: * This function does not require super-user privileges.
904: */
905: void
1.120 markus 906: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 907: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 908: {
909: char *host, *cp;
1.70 markus 910: char *server_user, *local_user;
911:
912: local_user = xstrdup(pw->pw_name);
913: server_user = options.user ? options.user : local_user;
1.51 markus 914:
915: /* Convert the user-supplied hostname into all lowercase. */
916: host = xstrdup(orighost);
917: for (cp = host; *cp; cp++)
918: if (isupper(*cp))
919: *cp = tolower(*cp);
920:
921: /* Exchange protocol version identification strings with the server. */
922: ssh_exchange_identification();
923:
924: /* Put the connection into non-blocking mode. */
925: packet_set_nonblocking();
926:
927: /* key exchange */
928: /* authenticate user */
1.59 markus 929: if (compat20) {
930: ssh_kex2(host, hostaddr);
1.120 markus 931: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 932: } else {
933: ssh_kex(host, hostaddr);
1.120 markus 934: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 935: }
1.97 markus 936: }
937:
938: void
939: ssh_put_password(char *password)
940: {
941: int size;
942: char *padded;
943:
1.99 deraadt 944: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 945: packet_put_cstring(password);
1.99 deraadt 946: return;
947: }
1.97 markus 948: size = roundup(strlen(password) + 1, 32);
949: padded = xmalloc(size);
950: memset(padded, 0, size);
951: strlcpy(padded, password, size);
952: packet_put_string(padded, size);
953: memset(padded, 0, size);
954: xfree(padded);
1.132 markus 955: }
956:
957: static int
958: show_key_from_file(const char *file, const char *host, int keytype)
959: {
960: Key *found;
961: char *fp;
962: int line, ret;
963:
964: found = key_new(keytype);
965: if ((ret = lookup_key_in_hostfile_by_type(file, host,
966: keytype, found, &line))) {
967: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 968: logit("WARNING: %s key found for host %s\n"
1.133 markus 969: "in %s:%d\n"
1.132 markus 970: "%s key fingerprint %s.",
971: key_type(found), host, file, line,
972: key_type(found), fp);
973: xfree(fp);
974: }
975: key_free(found);
976: return (ret);
977: }
978:
979: /* print all known host keys for a given host, but skip keys of given type */
980: static int
981: show_other_keys(const char *host, Key *key)
982: {
983: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
984: int i, found = 0;
985:
986: for (i = 0; type[i] != -1; i++) {
987: if (type[i] == key->type)
988: continue;
989: if (type[i] != KEY_RSA1 &&
990: show_key_from_file(options.user_hostfile2, host, type[i])) {
991: found = 1;
992: continue;
993: }
994: if (type[i] != KEY_RSA1 &&
995: show_key_from_file(options.system_hostfile2, host, type[i])) {
996: found = 1;
997: continue;
998: }
999: if (show_key_from_file(options.user_hostfile, host, type[i])) {
1000: found = 1;
1001: continue;
1002: }
1003: if (show_key_from_file(options.system_hostfile, host, type[i])) {
1004: found = 1;
1005: continue;
1006: }
1007: debug2("no key of type %d for host %s", type[i], host);
1008: }
1009: return (found);
1.150 jakob 1010: }
1011:
1012: static void
1013: warn_changed_key(Key *host_key)
1014: {
1015: char *fp;
1.151 jakob 1016: const char *type = key_type(host_key);
1.150 jakob 1017:
1018: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1019:
1020: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1021: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1022: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1023: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1024: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1025: error("It is also possible that the %s host key has just been changed.", type);
1026: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1027: type, fp);
1028: error("Please contact your system administrator.");
1029:
1030: xfree(fp);
1.171 reyk 1031: }
1032:
1033: /*
1034: * Execute a local command
1035: */
1036: int
1037: ssh_local_cmd(const char *args)
1038: {
1039: char *shell;
1040: pid_t pid;
1041: int status;
1042:
1043: if (!options.permit_local_command ||
1044: args == NULL || !*args)
1045: return (1);
1046:
1047: if ((shell = getenv("SHELL")) == NULL)
1048: shell = _PATH_BSHELL;
1049:
1050: pid = fork();
1051: if (pid == 0) {
1052: debug3("Executing %s -c \"%s\"", shell, args);
1053: execl(shell, shell, "-c", args, (char *)NULL);
1054: error("Couldn't execute %s -c \"%s\": %s",
1055: shell, args, strerror(errno));
1056: _exit(1);
1057: } else if (pid == -1)
1058: fatal("fork failed: %.100s", strerror(errno));
1059: while (waitpid(pid, &status, 0) == -1)
1060: if (errno != EINTR)
1061: fatal("Couldn't wait for child: %s", strerror(errno));
1062:
1063: if (!WIFEXITED(status))
1064: return (1);
1065:
1066: return (WEXITSTATUS(status));
1.1 deraadt 1067: }
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