Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.180
1.180 ! djm 1: /* $OpenBSD$ */
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>
1.172 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];
1.38 markus 66:
67: /* Convert the port number into a string. */
1.49 markus 68: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 69:
1.135 djm 70: /*
71: * Build the final command string in the buffer by making the
72: * appropriate substitutions to the given proxy command.
73: *
1.154 djm 74: * Use "exec" to avoid "sh -c" processes on some platforms
1.135 djm 75: * (e.g. Solaris)
76: */
1.179 djm 77: xasprintf(&tmp, "exec %s", proxy_command);
1.164 djm 78: command_string = percent_expand(tmp, "h", host,
79: "p", strport, (char *)NULL);
80: xfree(tmp);
1.38 markus 81:
82: /* Create pipes for communicating with the proxy. */
83: if (pipe(pin) < 0 || pipe(pout) < 0)
84: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 85: strerror(errno));
1.38 markus 86:
87: debug("Executing proxy command: %.500s", command_string);
88:
89: /* Fork and execute the proxy command. */
90: if ((pid = fork()) == 0) {
91: char *argv[10];
92:
93: /* Child. Permanently give up superuser privileges. */
1.124 markus 94: seteuid(original_real_uid);
95: setuid(original_real_uid);
1.38 markus 96:
97: /* Redirect stdin and stdout. */
98: close(pin[1]);
99: if (pin[0] != 0) {
100: if (dup2(pin[0], 0) < 0)
101: perror("dup2 stdin");
102: close(pin[0]);
103: }
104: close(pout[0]);
105: if (dup2(pout[1], 1) < 0)
106: perror("dup2 stdout");
107: /* Cannot be 1 because pin allocated two descriptors. */
108: close(pout[1]);
109:
110: /* Stderr is left as it is so that error messages get
111: printed on the user's terminal. */
1.89 markus 112: argv[0] = _PATH_BSHELL;
1.38 markus 113: argv[1] = "-c";
114: argv[2] = command_string;
115: argv[3] = NULL;
116:
117: /* Execute the proxy command. Note that we gave up any
118: extra privileges above. */
1.89 markus 119: execv(argv[0], argv);
120: perror(argv[0]);
1.38 markus 121: exit(1);
122: }
123: /* Parent. */
124: if (pid < 0)
125: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 126: else
127: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 128:
129: /* Close child side of the descriptors. */
130: close(pin[0]);
131: close(pout[1]);
132:
133: /* Free the command name. */
1.164 djm 134: xfree(command_string);
1.38 markus 135:
136: /* Set the connection file descriptors. */
137: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 138:
1.110 markus 139: /* Indicate OK return */
140: return 0;
1.1 deraadt 141: }
142:
1.39 deraadt 143: /*
144: * Creates a (possibly privileged) socket for use as the ssh connection.
145: */
1.109 itojun 146: static int
1.139 markus 147: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 148: {
1.105 markus 149: int sock, gaierr;
150: struct addrinfo hints, *res;
1.1 deraadt 151:
1.40 markus 152: /*
153: * If we are running as root and want to connect to a privileged
154: * port, bind our own socket to a privileged port.
155: */
1.38 markus 156: if (privileged) {
157: int p = IPPORT_RESERVED - 1;
1.124 markus 158: PRIV_START;
1.139 markus 159: sock = rresvport_af(&p, ai->ai_family);
1.124 markus 160: PRIV_END;
1.38 markus 161: if (sock < 0)
1.139 markus 162: error("rresvport: af=%d %.100s", ai->ai_family,
163: strerror(errno));
1.55 markus 164: else
165: debug("Allocated local port %d.", p);
1.105 markus 166: return sock;
167: }
1.139 markus 168: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.105 markus 169: if (sock < 0)
170: error("socket: %.100s", strerror(errno));
171:
172: /* Bind the socket to an alternative local IP address */
173: if (options.bind_address == NULL)
174: return sock;
175:
176: memset(&hints, 0, sizeof(hints));
1.139 markus 177: hints.ai_family = ai->ai_family;
178: hints.ai_socktype = ai->ai_socktype;
179: hints.ai_protocol = ai->ai_protocol;
1.105 markus 180: hints.ai_flags = AI_PASSIVE;
181: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
182: if (gaierr) {
183: error("getaddrinfo: %s: %s", options.bind_address,
184: gai_strerror(gaierr));
185: close(sock);
186: return -1;
187: }
188: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
189: error("bind: %s: %s", options.bind_address, strerror(errno));
190: close(sock);
191: freeaddrinfo(res);
192: return -1;
1.38 markus 193: }
1.105 markus 194: freeaddrinfo(res);
1.38 markus 195: return sock;
1.1 deraadt 196: }
197:
1.141 djm 198: static int
199: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
200: socklen_t addrlen, int timeout)
201: {
202: fd_set *fdset;
203: struct timeval tv;
204: socklen_t optlen;
1.179 djm 205: int optval, rc, result = -1;
1.141 djm 206:
207: if (timeout <= 0)
208: return (connect(sockfd, serv_addr, addrlen));
209:
1.156 djm 210: set_nonblock(sockfd);
1.141 djm 211: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 212: if (rc == 0) {
213: unset_nonblock(sockfd);
1.141 djm 214: return (0);
1.156 djm 215: }
1.141 djm 216: if (errno != EINPROGRESS)
217: return (-1);
218:
1.179 djm 219: fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
220: sizeof(fd_mask));
1.141 djm 221: FD_SET(sockfd, fdset);
222: tv.tv_sec = timeout;
223: tv.tv_usec = 0;
224:
1.162 deraadt 225: for (;;) {
1.141 djm 226: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
227: if (rc != -1 || errno != EINTR)
228: break;
229: }
230:
1.162 deraadt 231: switch (rc) {
1.141 djm 232: case 0:
233: /* Timed out */
234: errno = ETIMEDOUT;
1.142 djm 235: break;
1.141 djm 236: case -1:
237: /* Select error */
1.154 djm 238: debug("select: %s", strerror(errno));
1.142 djm 239: break;
1.141 djm 240: case 1:
241: /* Completed or failed */
242: optval = 0;
243: optlen = sizeof(optval);
1.154 djm 244: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 245: &optlen) == -1) {
1.154 djm 246: debug("getsockopt: %s", strerror(errno));
1.142 djm 247: break;
1.148 markus 248: }
1.141 djm 249: if (optval != 0) {
250: errno = optval;
1.142 djm 251: break;
1.141 djm 252: }
1.142 djm 253: result = 0;
1.156 djm 254: unset_nonblock(sockfd);
1.141 djm 255: break;
256: default:
257: /* Should not occur */
258: fatal("Bogus return (%d) from select()", rc);
259: }
260:
1.142 djm 261: xfree(fdset);
262: return (result);
1.141 djm 263: }
264:
1.39 deraadt 265: /*
1.49 markus 266: * Opens a TCP/IP connection to the remote server on the given host.
267: * The address of the remote host will be returned in hostaddr.
1.124 markus 268: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 269: * a privileged port will be allocated to make the connection.
1.124 markus 270: * This requires super-user privileges if needpriv is true.
1.39 deraadt 271: * Connection_attempts specifies the maximum number of tries (one per
272: * second). If proxy_command is non-NULL, it specifies the command (with %h
273: * and %p substituted for host and port, respectively) to use to contact
274: * the daemon.
275: */
1.38 markus 276: int
1.49 markus 277: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 278: u_short port, int family, int connection_attempts,
1.124 markus 279: int needpriv, const char *proxy_command)
1.1 deraadt 280: {
1.90 markus 281: int gaierr;
282: int on = 1;
1.49 markus 283: int sock = -1, attempt;
1.90 markus 284: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 285: struct addrinfo hints, *ai, *aitop;
1.38 markus 286:
1.136 markus 287: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 288:
289: /* If a proxy command is given, connect using it. */
290: if (proxy_command != NULL)
1.124 markus 291: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 292:
293: /* No proxy command. */
294:
1.49 markus 295: memset(&hints, 0, sizeof(hints));
1.115 markus 296: hints.ai_family = family;
1.49 markus 297: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 298: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 299: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 300: fatal("%s: %.100s: %s", __progname, host,
301: gai_strerror(gaierr));
1.38 markus 302:
1.46 markus 303: /*
304: * Try to connect several times. On some machines, the first time
305: * will sometimes fail. In general socket code appears to behave
306: * quite magically on many machines.
1.110 markus 307: */
308: for (attempt = 0; ;) {
1.38 markus 309: if (attempt > 0)
310: debug("Trying again...");
311:
1.49 markus 312: /* Loop through addresses for this host, and try each one in
1.68 markus 313: sequence until the connection succeeds. */
1.49 markus 314: for (ai = aitop; ai; ai = ai->ai_next) {
315: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
316: continue;
317: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
318: ntop, sizeof(ntop), strport, sizeof(strport),
319: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
320: error("ssh_connect: getnameinfo failed");
321: continue;
322: }
323: debug("Connecting to %.200s [%.100s] port %s.",
324: host, ntop, strport);
325:
326: /* Create a socket for connecting. */
1.139 markus 327: sock = ssh_create_socket(needpriv, ai);
1.49 markus 328: if (sock < 0)
1.110 markus 329: /* Any error is already output */
1.49 markus 330: continue;
331:
1.141 djm 332: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
333: options.connection_timeout) >= 0) {
1.49 markus 334: /* Successful connection. */
1.102 markus 335: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 336: break;
1.49 markus 337: } else {
1.131 itojun 338: debug("connect to address %s port %s: %s",
339: ntop, strport, strerror(errno));
1.40 markus 340: /*
341: * Close the failed socket; there appear to
342: * be some problems when reusing a socket for
343: * which connect() has already returned an
344: * error.
345: */
1.38 markus 346: close(sock);
347: }
348: }
1.49 markus 349: if (ai)
350: break; /* Successful connection. */
1.1 deraadt 351:
1.110 markus 352: attempt++;
353: if (attempt >= connection_attempts)
354: break;
1.38 markus 355: /* Sleep a moment before retrying. */
356: sleep(1);
357: }
1.49 markus 358:
359: freeaddrinfo(aitop);
360:
1.38 markus 361: /* Return failure if we didn't get a successful connection. */
1.130 itojun 362: if (attempt >= connection_attempts) {
1.159 markus 363: error("ssh: connect to host %s port %s: %s",
1.130 itojun 364: host, strport, strerror(errno));
1.159 markus 365: return (-1);
1.130 itojun 366: }
1.38 markus 367:
368: debug("Connection established.");
1.90 markus 369:
1.155 markus 370: /* Set SO_KEEPALIVE if requested. */
371: if (options.tcp_keep_alive &&
1.90 markus 372: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
373: sizeof(on)) < 0)
374: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 375:
376: /* Set the connection. */
377: packet_set_connection(sock, sock);
1.1 deraadt 378:
1.110 markus 379: return 0;
1.59 markus 380: }
381:
1.43 markus 382: /*
1.39 deraadt 383: * Waits for the server identification string, and sends our own
384: * identification string.
385: */
1.109 itojun 386: static void
1.95 itojun 387: ssh_exchange_identification(void)
1.1 deraadt 388: {
1.38 markus 389: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 390: int remote_major, remote_minor, mismatch;
1.38 markus 391: int connection_in = packet_get_connection_in();
392: int connection_out = packet_get_connection_out();
1.93 stevesk 393: int minor1 = PROTOCOL_MINOR_1;
1.165 djm 394: u_int i;
1.38 markus 395:
1.163 avsm 396: /* Read other side's version identification. */
1.75 markus 397: for (;;) {
398: for (i = 0; i < sizeof(buf) - 1; i++) {
1.163 avsm 399: size_t len = atomicio(read, connection_in, &buf[i], 1);
400:
1.167 djm 401: if (len != 1 && errno == EPIPE)
1.163 avsm 402: fatal("ssh_exchange_identification: Connection closed by remote host");
403: else if (len != 1)
1.75 markus 404: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
405: if (buf[i] == '\r') {
406: buf[i] = '\n';
407: buf[i + 1] = 0;
408: continue; /**XXX wait for \n */
409: }
410: if (buf[i] == '\n') {
411: buf[i + 1] = 0;
412: break;
413: }
1.38 markus 414: }
1.75 markus 415: buf[sizeof(buf) - 1] = 0;
1.76 markus 416: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 417: break;
1.75 markus 418: debug("ssh_exchange_identification: %s", buf);
1.38 markus 419: }
1.59 markus 420: server_version_string = xstrdup(buf);
1.38 markus 421:
1.40 markus 422: /*
423: * Check that the versions match. In future this might accept
424: * several versions and set appropriate flags to handle them.
425: */
1.59 markus 426: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
427: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 428: fatal("Bad remote protocol version identification: '%.100s'", buf);
429: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 430: remote_major, remote_minor, remote_version);
1.38 markus 431:
1.59 markus 432: compat_datafellows(remote_version);
1.64 markus 433: mismatch = 0;
1.59 markus 434:
1.116 deraadt 435: switch (remote_major) {
1.64 markus 436: case 1:
437: if (remote_minor == 99 &&
438: (options.protocol & SSH_PROTO_2) &&
439: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
440: enable_compat20();
441: break;
442: }
443: if (!(options.protocol & SSH_PROTO_1)) {
444: mismatch = 1;
445: break;
446: }
447: if (remote_minor < 3) {
448: fatal("Remote machine has too old SSH software version.");
1.81 markus 449: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 450: /* We speak 1.3, too. */
451: enable_compat13();
1.81 markus 452: minor1 = 3;
1.64 markus 453: if (options.forward_agent) {
1.138 itojun 454: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 455: options.forward_agent = 0;
456: }
457: }
458: break;
459: case 2:
460: if (options.protocol & SSH_PROTO_2) {
461: enable_compat20();
462: break;
1.38 markus 463: }
1.64 markus 464: /* FALLTHROUGH */
1.68 markus 465: default:
1.64 markus 466: mismatch = 1;
467: break;
1.38 markus 468: }
1.64 markus 469: if (mismatch)
1.38 markus 470: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 471: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
472: remote_major);
1.38 markus 473: /* Send our own protocol version identification. */
474: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 475: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 476: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 477: SSH_VERSION);
1.146 deraadt 478: if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 479: fatal("write: %.100s", strerror(errno));
1.59 markus 480: client_version_string = xstrdup(buf);
481: chop(client_version_string);
482: chop(server_version_string);
483: debug("Local version string %.100s", client_version_string);
1.1 deraadt 484: }
485:
1.96 markus 486: /* defaults to 'no' */
1.109 itojun 487: static int
1.112 markus 488: confirm(const char *prompt)
1.1 deraadt 489: {
1.119 markus 490: const char *msg, *again = "Please type 'yes' or 'no': ";
491: char *p;
492: int ret = -1;
1.96 markus 493:
494: if (options.batch_mode)
495: return 0;
1.119 markus 496: for (msg = prompt;;msg = again) {
497: p = read_passphrase(msg, RP_ECHO);
498: if (p == NULL ||
499: (p[0] == '\0') || (p[0] == '\n') ||
500: strncasecmp(p, "no", 2) == 0)
501: ret = 0;
1.127 markus 502: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 503: ret = 1;
504: if (p)
505: xfree(p);
506: if (ret != -1)
507: return ret;
1.1 deraadt 508: }
509: }
510:
1.39 deraadt 511: /*
1.108 markus 512: * check whether the supplied host key is valid, return -1 if the key
513: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 514: */
1.109 itojun 515: static int
1.70 markus 516: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 517: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 518: {
1.58 markus 519: Key *file_key;
1.152 jakob 520: const char *type = key_type(host_key);
1.46 markus 521: char *ip = NULL;
1.100 markus 522: char hostline[1000], *hostp, *fp;
1.38 markus 523: HostStatus host_status;
524: HostStatus ip_status;
1.161 djm 525: int r, local = 0, host_ip_differ = 0;
1.49 markus 526: char ntop[NI_MAXHOST];
1.119 markus 527: char msg[1024];
1.145 jakob 528: int len, host_line, ip_line;
1.85 markus 529: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 530:
531: /*
532: * Force accepting of the host key for loopback/localhost. The
533: * problem is that if the home directory is NFS-mounted to multiple
534: * machines, localhost will refer to a different machine in each of
535: * them, and the user will get bogus HOST_CHANGED warnings. This
536: * essentially disables host authentication for localhost; however,
537: * this is probably not a real problem.
538: */
1.70 markus 539: /** hostaddr == 0! */
1.49 markus 540: switch (hostaddr->sa_family) {
541: case AF_INET:
1.108 markus 542: local = (ntohl(((struct sockaddr_in *)hostaddr)->
1.168 djm 543: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 544: break;
545: case AF_INET6:
1.108 markus 546: local = IN6_IS_ADDR_LOOPBACK(
547: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 548: break;
549: default:
550: local = 0;
551: break;
552: }
1.111 markus 553: if (options.no_host_authentication_for_localhost == 1 && local &&
554: options.host_key_alias == NULL) {
1.88 markus 555: debug("Forcing accepting of host key for "
556: "loopback/localhost.");
1.108 markus 557: return 0;
1.49 markus 558: }
1.42 markus 559:
560: /*
1.88 markus 561: * We don't have the remote ip-address for connections
562: * using a proxy command
1.42 markus 563: */
1.84 markus 564: if (options.proxy_command == NULL) {
565: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 566: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 567: fatal("check_host_key: getnameinfo failed");
568: ip = xstrdup(ntop);
569: } else {
570: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 571: }
1.88 markus 572: /*
573: * Turn off check_host_ip if the connection is to localhost, via proxy
574: * command or if we don't have a hostname to compare with
575: */
576: if (options.check_host_ip &&
577: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
578: options.check_host_ip = 0;
1.86 markus 579:
580: /*
581: * Allow the user to record the key under a different name. This is
582: * useful for ssh tunneling over forwarded connections or if you run
583: * multiple sshd's on different ports on the same machine.
584: */
585: if (options.host_key_alias != NULL) {
586: host = options.host_key_alias;
587: debug("using hostkeyalias: %s", host);
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);
1.108 markus 849: return 0;
850:
851: fail:
852: xfree(ip);
853: return -1;
854: }
855:
1.140 jakob 856: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 857: int
858: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
859: {
860: struct stat st;
1.153 jakob 861: int flags = 0;
1.140 jakob 862:
1.153 jakob 863: if (options.verify_host_key_dns &&
864: verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
865:
866: if (flags & DNS_VERIFY_FOUND) {
867:
868: if (options.verify_host_key_dns == 1 &&
869: flags & DNS_VERIFY_MATCH &&
870: flags & DNS_VERIFY_SECURE)
871: return 0;
872:
873: if (flags & DNS_VERIFY_MATCH) {
874: matching_host_key_dns = 1;
875: } else {
876: warn_changed_key(host_key);
877: error("Update the SSHFP RR in DNS with the new "
878: "host key to get rid of this message.");
879: }
1.140 jakob 880: }
881: }
1.108 markus 882:
883: /* return ok if the key can be found in an old keyfile */
884: if (stat(options.system_hostfile2, &st) == 0 ||
885: stat(options.user_hostfile2, &st) == 0) {
886: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
887: options.user_hostfile2, options.system_hostfile2) == 0)
888: return 0;
889: }
890: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
891: options.user_hostfile, options.system_hostfile);
1.51 markus 892: }
1.70 markus 893:
1.51 markus 894: /*
895: * Starts a dialog with the server, and authenticates the current user on the
896: * server. This does not need any extra privileges. The basic connection
897: * to the server must already have been established before this is called.
898: * If login fails, this function prints an error and never returns.
899: * This function does not require super-user privileges.
900: */
901: void
1.120 markus 902: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 903: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 904: {
905: char *host, *cp;
1.70 markus 906: char *server_user, *local_user;
907:
908: local_user = xstrdup(pw->pw_name);
909: server_user = options.user ? options.user : local_user;
1.51 markus 910:
911: /* Convert the user-supplied hostname into all lowercase. */
912: host = xstrdup(orighost);
913: for (cp = host; *cp; cp++)
914: if (isupper(*cp))
1.178 deraadt 915: *cp = (char)tolower(*cp);
1.51 markus 916:
917: /* Exchange protocol version identification strings with the server. */
918: ssh_exchange_identification();
919:
920: /* Put the connection into non-blocking mode. */
921: packet_set_nonblocking();
922:
923: /* key exchange */
924: /* authenticate user */
1.59 markus 925: if (compat20) {
926: ssh_kex2(host, hostaddr);
1.120 markus 927: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 928: } else {
929: ssh_kex(host, hostaddr);
1.120 markus 930: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 931: }
1.97 markus 932: }
933:
934: void
935: ssh_put_password(char *password)
936: {
937: int size;
938: char *padded;
939:
1.99 deraadt 940: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 941: packet_put_cstring(password);
1.99 deraadt 942: return;
943: }
1.97 markus 944: size = roundup(strlen(password) + 1, 32);
1.179 djm 945: padded = xcalloc(1, size);
1.97 markus 946: strlcpy(padded, password, size);
947: packet_put_string(padded, size);
948: memset(padded, 0, size);
949: xfree(padded);
1.132 markus 950: }
951:
952: static int
953: show_key_from_file(const char *file, const char *host, int keytype)
954: {
955: Key *found;
956: char *fp;
957: int line, ret;
958:
959: found = key_new(keytype);
960: if ((ret = lookup_key_in_hostfile_by_type(file, host,
961: keytype, found, &line))) {
962: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 963: logit("WARNING: %s key found for host %s\n"
1.133 markus 964: "in %s:%d\n"
1.132 markus 965: "%s key fingerprint %s.",
966: key_type(found), host, file, line,
967: key_type(found), fp);
968: xfree(fp);
969: }
970: key_free(found);
971: return (ret);
972: }
973:
974: /* print all known host keys for a given host, but skip keys of given type */
975: static int
976: show_other_keys(const char *host, Key *key)
977: {
978: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
979: int i, found = 0;
980:
981: for (i = 0; type[i] != -1; i++) {
982: if (type[i] == key->type)
983: continue;
984: if (type[i] != KEY_RSA1 &&
985: show_key_from_file(options.user_hostfile2, host, type[i])) {
986: found = 1;
987: continue;
988: }
989: if (type[i] != KEY_RSA1 &&
990: show_key_from_file(options.system_hostfile2, host, type[i])) {
991: found = 1;
992: continue;
993: }
994: if (show_key_from_file(options.user_hostfile, host, type[i])) {
995: found = 1;
996: continue;
997: }
998: if (show_key_from_file(options.system_hostfile, host, type[i])) {
999: found = 1;
1000: continue;
1001: }
1002: debug2("no key of type %d for host %s", type[i], host);
1003: }
1004: return (found);
1.150 jakob 1005: }
1006:
1007: static void
1008: warn_changed_key(Key *host_key)
1009: {
1010: char *fp;
1.151 jakob 1011: const char *type = key_type(host_key);
1.150 jakob 1012:
1013: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1014:
1015: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1016: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1017: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1018: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1019: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1020: error("It is also possible that the %s host key has just been changed.", type);
1021: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1022: type, fp);
1023: error("Please contact your system administrator.");
1024:
1025: xfree(fp);
1.171 reyk 1026: }
1027:
1028: /*
1029: * Execute a local command
1030: */
1031: int
1032: ssh_local_cmd(const char *args)
1033: {
1034: char *shell;
1035: pid_t pid;
1036: int status;
1037:
1038: if (!options.permit_local_command ||
1039: args == NULL || !*args)
1040: return (1);
1041:
1042: if ((shell = getenv("SHELL")) == NULL)
1043: shell = _PATH_BSHELL;
1044:
1045: pid = fork();
1046: if (pid == 0) {
1047: debug3("Executing %s -c \"%s\"", shell, args);
1048: execl(shell, shell, "-c", args, (char *)NULL);
1049: error("Couldn't execute %s -c \"%s\": %s",
1050: shell, args, strerror(errno));
1051: _exit(1);
1052: } else if (pid == -1)
1053: fatal("fork failed: %.100s", strerror(errno));
1054: while (waitpid(pid, &status, 0) == -1)
1055: if (errno != EINTR)
1056: fatal("Couldn't wait for child: %s", strerror(errno));
1057:
1058: if (!WIFEXITED(status))
1059: return (1);
1060:
1061: return (WEXITSTATUS(status));
1.1 deraadt 1062: }
![[BACK]](/icons/back.gif){kind=icon}
Return to sshconnect.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh