Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.179
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:
17: #include <sys/types.h>
18: #include <sys/wait.h>
1.175 stevesk 19: #include <sys/stat.h>
1.172 stevesk 20:
1.176 stevesk 21: #include <ctype.h>
1.172 stevesk 22: #include <paths.h>
1.71 markus 23:
1.91 markus 24: #include "ssh.h"
1.1 deraadt 25: #include "xmalloc.h"
26: #include "rsa.h"
1.59 markus 27: #include "buffer.h"
1.1 deraadt 28: #include "packet.h"
29: #include "uidswap.h"
1.21 markus 30: #include "compat.h"
1.58 markus 31: #include "key.h"
1.71 markus 32: #include "sshconnect.h"
1.58 markus 33: #include "hostfile.h"
1.91 markus 34: #include "log.h"
35: #include "readconf.h"
36: #include "atomicio.h"
37: #include "misc.h"
1.140 jakob 38: #include "dns.h"
39:
1.70 markus 40: char *client_version_string = NULL;
41: char *server_version_string = NULL;
1.59 markus 42:
1.169 stevesk 43: static int matching_host_key_dns = 0;
1.145 jakob 44:
1.124 markus 45: /* import */
1.43 markus 46: extern Options options;
1.50 markus 47: extern char *__progname;
1.124 markus 48: extern uid_t original_real_uid;
49: extern uid_t original_effective_uid;
1.135 djm 50: extern pid_t proxy_command_pid;
1.91 markus 51:
1.132 markus 52: static int show_other_keys(const char *, Key *);
1.150 jakob 53: static void warn_changed_key(Key *);
1.132 markus 54:
1.39 deraadt 55: /*
56: * Connect to the given ssh server using a proxy command.
57: */
1.109 itojun 58: static int
1.124 markus 59: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 60: {
1.164 djm 61: char *command_string, *tmp;
1.38 markus 62: int pin[2], pout[2];
1.69 deraadt 63: pid_t pid;
1.49 markus 64: char strport[NI_MAXSERV];
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: */
1.179 ! djm 76: xasprintf(&tmp, "exec %s", proxy_command);
1.164 djm 77: command_string = percent_expand(tmp, "h", host,
78: "p", strport, (char *)NULL);
79: xfree(tmp);
1.38 markus 80:
81: /* Create pipes for communicating with the proxy. */
82: if (pipe(pin) < 0 || pipe(pout) < 0)
83: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 84: strerror(errno));
1.38 markus 85:
86: debug("Executing proxy command: %.500s", command_string);
87:
88: /* Fork and execute the proxy command. */
89: if ((pid = fork()) == 0) {
90: char *argv[10];
91:
92: /* Child. Permanently give up superuser privileges. */
1.124 markus 93: seteuid(original_real_uid);
94: setuid(original_real_uid);
1.38 markus 95:
96: /* Redirect stdin and stdout. */
97: close(pin[1]);
98: if (pin[0] != 0) {
99: if (dup2(pin[0], 0) < 0)
100: perror("dup2 stdin");
101: close(pin[0]);
102: }
103: close(pout[0]);
104: if (dup2(pout[1], 1) < 0)
105: perror("dup2 stdout");
106: /* Cannot be 1 because pin allocated two descriptors. */
107: close(pout[1]);
108:
109: /* Stderr is left as it is so that error messages get
110: printed on the user's terminal. */
1.89 markus 111: argv[0] = _PATH_BSHELL;
1.38 markus 112: argv[1] = "-c";
113: argv[2] = command_string;
114: argv[3] = NULL;
115:
116: /* Execute the proxy command. Note that we gave up any
117: extra privileges above. */
1.89 markus 118: execv(argv[0], argv);
119: perror(argv[0]);
1.38 markus 120: exit(1);
121: }
122: /* Parent. */
123: if (pid < 0)
124: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 125: else
126: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 127:
128: /* Close child side of the descriptors. */
129: close(pin[0]);
130: close(pout[1]);
131:
132: /* Free the command name. */
1.164 djm 133: xfree(command_string);
1.38 markus 134:
135: /* Set the connection file descriptors. */
136: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 137:
1.110 markus 138: /* Indicate OK return */
139: return 0;
1.1 deraadt 140: }
141:
1.39 deraadt 142: /*
143: * Creates a (possibly privileged) socket for use as the ssh connection.
144: */
1.109 itojun 145: static int
1.139 markus 146: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 147: {
1.105 markus 148: int sock, gaierr;
149: struct addrinfo hints, *res;
1.1 deraadt 150:
1.40 markus 151: /*
152: * If we are running as root and want to connect to a privileged
153: * port, bind our own socket to a privileged port.
154: */
1.38 markus 155: if (privileged) {
156: int p = IPPORT_RESERVED - 1;
1.124 markus 157: PRIV_START;
1.139 markus 158: sock = rresvport_af(&p, ai->ai_family);
1.124 markus 159: PRIV_END;
1.38 markus 160: if (sock < 0)
1.139 markus 161: error("rresvport: af=%d %.100s", ai->ai_family,
162: strerror(errno));
1.55 markus 163: else
164: debug("Allocated local port %d.", p);
1.105 markus 165: return sock;
166: }
1.139 markus 167: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.105 markus 168: if (sock < 0)
169: error("socket: %.100s", strerror(errno));
170:
171: /* Bind the socket to an alternative local IP address */
172: if (options.bind_address == NULL)
173: return sock;
174:
175: memset(&hints, 0, sizeof(hints));
1.139 markus 176: hints.ai_family = ai->ai_family;
177: hints.ai_socktype = ai->ai_socktype;
178: hints.ai_protocol = ai->ai_protocol;
1.105 markus 179: hints.ai_flags = AI_PASSIVE;
180: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
181: if (gaierr) {
182: error("getaddrinfo: %s: %s", options.bind_address,
183: gai_strerror(gaierr));
184: close(sock);
185: return -1;
186: }
187: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
188: error("bind: %s: %s", options.bind_address, strerror(errno));
189: close(sock);
190: freeaddrinfo(res);
191: return -1;
1.38 markus 192: }
1.105 markus 193: freeaddrinfo(res);
1.38 markus 194: return sock;
1.1 deraadt 195: }
196:
1.141 djm 197: static int
198: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
199: socklen_t addrlen, int timeout)
200: {
201: fd_set *fdset;
202: struct timeval tv;
203: socklen_t optlen;
1.179 ! djm 204: int optval, rc, result = -1;
1.141 djm 205:
206: if (timeout <= 0)
207: return (connect(sockfd, serv_addr, addrlen));
208:
1.156 djm 209: set_nonblock(sockfd);
1.141 djm 210: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 211: if (rc == 0) {
212: unset_nonblock(sockfd);
1.141 djm 213: return (0);
1.156 djm 214: }
1.141 djm 215: if (errno != EINPROGRESS)
216: return (-1);
217:
1.179 ! djm 218: fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
! 219: sizeof(fd_mask));
1.141 djm 220: FD_SET(sockfd, fdset);
221: tv.tv_sec = timeout;
222: tv.tv_usec = 0;
223:
1.162 deraadt 224: for (;;) {
1.141 djm 225: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
226: if (rc != -1 || errno != EINTR)
227: break;
228: }
229:
1.162 deraadt 230: switch (rc) {
1.141 djm 231: case 0:
232: /* Timed out */
233: errno = ETIMEDOUT;
1.142 djm 234: break;
1.141 djm 235: case -1:
236: /* Select error */
1.154 djm 237: debug("select: %s", strerror(errno));
1.142 djm 238: break;
1.141 djm 239: case 1:
240: /* Completed or failed */
241: optval = 0;
242: optlen = sizeof(optval);
1.154 djm 243: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 244: &optlen) == -1) {
1.154 djm 245: debug("getsockopt: %s", strerror(errno));
1.142 djm 246: break;
1.148 markus 247: }
1.141 djm 248: if (optval != 0) {
249: errno = optval;
1.142 djm 250: break;
1.141 djm 251: }
1.142 djm 252: result = 0;
1.156 djm 253: unset_nonblock(sockfd);
1.141 djm 254: break;
255: default:
256: /* Should not occur */
257: fatal("Bogus return (%d) from select()", rc);
258: }
259:
1.142 djm 260: xfree(fdset);
261: return (result);
1.141 djm 262: }
263:
1.39 deraadt 264: /*
1.49 markus 265: * Opens a TCP/IP connection to the remote server on the given host.
266: * The address of the remote host will be returned in hostaddr.
1.124 markus 267: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 268: * a privileged port will be allocated to make the connection.
1.124 markus 269: * This requires super-user privileges if needpriv is true.
1.39 deraadt 270: * Connection_attempts specifies the maximum number of tries (one per
271: * second). If proxy_command is non-NULL, it specifies the command (with %h
272: * and %p substituted for host and port, respectively) to use to contact
273: * the daemon.
274: */
1.38 markus 275: int
1.49 markus 276: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 277: u_short port, int family, int connection_attempts,
1.124 markus 278: int needpriv, const char *proxy_command)
1.1 deraadt 279: {
1.90 markus 280: int gaierr;
281: int on = 1;
1.49 markus 282: int sock = -1, attempt;
1.90 markus 283: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 284: struct addrinfo hints, *ai, *aitop;
1.38 markus 285:
1.136 markus 286: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 287:
288: /* If a proxy command is given, connect using it. */
289: if (proxy_command != NULL)
1.124 markus 290: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 291:
292: /* No proxy command. */
293:
1.49 markus 294: memset(&hints, 0, sizeof(hints));
1.115 markus 295: hints.ai_family = family;
1.49 markus 296: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 297: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 298: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 299: fatal("%s: %.100s: %s", __progname, host,
300: gai_strerror(gaierr));
1.38 markus 301:
1.46 markus 302: /*
303: * Try to connect several times. On some machines, the first time
304: * will sometimes fail. In general socket code appears to behave
305: * quite magically on many machines.
1.110 markus 306: */
307: for (attempt = 0; ;) {
1.38 markus 308: if (attempt > 0)
309: debug("Trying again...");
310:
1.49 markus 311: /* Loop through addresses for this host, and try each one in
1.68 markus 312: sequence until the connection succeeds. */
1.49 markus 313: for (ai = aitop; ai; ai = ai->ai_next) {
314: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
315: continue;
316: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
317: ntop, sizeof(ntop), strport, sizeof(strport),
318: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
319: error("ssh_connect: getnameinfo failed");
320: continue;
321: }
322: debug("Connecting to %.200s [%.100s] port %s.",
323: host, ntop, strport);
324:
325: /* Create a socket for connecting. */
1.139 markus 326: sock = ssh_create_socket(needpriv, ai);
1.49 markus 327: if (sock < 0)
1.110 markus 328: /* Any error is already output */
1.49 markus 329: continue;
330:
1.141 djm 331: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
332: options.connection_timeout) >= 0) {
1.49 markus 333: /* Successful connection. */
1.102 markus 334: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 335: break;
1.49 markus 336: } else {
1.131 itojun 337: debug("connect to address %s port %s: %s",
338: ntop, strport, strerror(errno));
1.40 markus 339: /*
340: * Close the failed socket; there appear to
341: * be some problems when reusing a socket for
342: * which connect() has already returned an
343: * error.
344: */
1.38 markus 345: close(sock);
346: }
347: }
1.49 markus 348: if (ai)
349: break; /* Successful connection. */
1.1 deraadt 350:
1.110 markus 351: attempt++;
352: if (attempt >= connection_attempts)
353: break;
1.38 markus 354: /* Sleep a moment before retrying. */
355: sleep(1);
356: }
1.49 markus 357:
358: freeaddrinfo(aitop);
359:
1.38 markus 360: /* Return failure if we didn't get a successful connection. */
1.130 itojun 361: if (attempt >= connection_attempts) {
1.159 markus 362: error("ssh: connect to host %s port %s: %s",
1.130 itojun 363: host, strport, strerror(errno));
1.159 markus 364: return (-1);
1.130 itojun 365: }
1.38 markus 366:
367: debug("Connection established.");
1.90 markus 368:
1.155 markus 369: /* Set SO_KEEPALIVE if requested. */
370: if (options.tcp_keep_alive &&
1.90 markus 371: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
372: sizeof(on)) < 0)
373: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 374:
375: /* Set the connection. */
376: packet_set_connection(sock, sock);
1.1 deraadt 377:
1.110 markus 378: return 0;
1.59 markus 379: }
380:
1.43 markus 381: /*
1.39 deraadt 382: * Waits for the server identification string, and sends our own
383: * identification string.
384: */
1.109 itojun 385: static void
1.95 itojun 386: ssh_exchange_identification(void)
1.1 deraadt 387: {
1.38 markus 388: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 389: int remote_major, remote_minor, mismatch;
1.38 markus 390: int connection_in = packet_get_connection_in();
391: int connection_out = packet_get_connection_out();
1.93 stevesk 392: int minor1 = PROTOCOL_MINOR_1;
1.165 djm 393: u_int i;
1.38 markus 394:
1.163 avsm 395: /* Read other side's version identification. */
1.75 markus 396: for (;;) {
397: for (i = 0; i < sizeof(buf) - 1; i++) {
1.163 avsm 398: size_t len = atomicio(read, connection_in, &buf[i], 1);
399:
1.167 djm 400: if (len != 1 && errno == EPIPE)
1.163 avsm 401: fatal("ssh_exchange_identification: Connection closed by remote host");
402: else if (len != 1)
1.75 markus 403: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
404: if (buf[i] == '\r') {
405: buf[i] = '\n';
406: buf[i + 1] = 0;
407: continue; /**XXX wait for \n */
408: }
409: if (buf[i] == '\n') {
410: buf[i + 1] = 0;
411: break;
412: }
1.38 markus 413: }
1.75 markus 414: buf[sizeof(buf) - 1] = 0;
1.76 markus 415: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 416: break;
1.75 markus 417: debug("ssh_exchange_identification: %s", buf);
1.38 markus 418: }
1.59 markus 419: server_version_string = xstrdup(buf);
1.38 markus 420:
1.40 markus 421: /*
422: * Check that the versions match. In future this might accept
423: * several versions and set appropriate flags to handle them.
424: */
1.59 markus 425: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
426: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 427: fatal("Bad remote protocol version identification: '%.100s'", buf);
428: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 429: remote_major, remote_minor, remote_version);
1.38 markus 430:
1.59 markus 431: compat_datafellows(remote_version);
1.64 markus 432: mismatch = 0;
1.59 markus 433:
1.116 deraadt 434: switch (remote_major) {
1.64 markus 435: case 1:
436: if (remote_minor == 99 &&
437: (options.protocol & SSH_PROTO_2) &&
438: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
439: enable_compat20();
440: break;
441: }
442: if (!(options.protocol & SSH_PROTO_1)) {
443: mismatch = 1;
444: break;
445: }
446: if (remote_minor < 3) {
447: fatal("Remote machine has too old SSH software version.");
1.81 markus 448: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 449: /* We speak 1.3, too. */
450: enable_compat13();
1.81 markus 451: minor1 = 3;
1.64 markus 452: if (options.forward_agent) {
1.138 itojun 453: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 454: options.forward_agent = 0;
455: }
456: }
457: break;
458: case 2:
459: if (options.protocol & SSH_PROTO_2) {
460: enable_compat20();
461: break;
1.38 markus 462: }
1.64 markus 463: /* FALLTHROUGH */
1.68 markus 464: default:
1.64 markus 465: mismatch = 1;
466: break;
1.38 markus 467: }
1.64 markus 468: if (mismatch)
1.38 markus 469: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 470: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
471: remote_major);
1.38 markus 472: /* Send our own protocol version identification. */
473: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 474: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 475: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 476: SSH_VERSION);
1.146 deraadt 477: if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 478: fatal("write: %.100s", strerror(errno));
1.59 markus 479: client_version_string = xstrdup(buf);
480: chop(client_version_string);
481: chop(server_version_string);
482: debug("Local version string %.100s", client_version_string);
1.1 deraadt 483: }
484:
1.96 markus 485: /* defaults to 'no' */
1.109 itojun 486: static int
1.112 markus 487: confirm(const char *prompt)
1.1 deraadt 488: {
1.119 markus 489: const char *msg, *again = "Please type 'yes' or 'no': ";
490: char *p;
491: int ret = -1;
1.96 markus 492:
493: if (options.batch_mode)
494: return 0;
1.119 markus 495: for (msg = prompt;;msg = again) {
496: p = read_passphrase(msg, RP_ECHO);
497: if (p == NULL ||
498: (p[0] == '\0') || (p[0] == '\n') ||
499: strncasecmp(p, "no", 2) == 0)
500: ret = 0;
1.127 markus 501: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 502: ret = 1;
503: if (p)
504: xfree(p);
505: if (ret != -1)
506: return ret;
1.1 deraadt 507: }
508: }
509:
1.39 deraadt 510: /*
1.108 markus 511: * check whether the supplied host key is valid, return -1 if the key
512: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 513: */
1.109 itojun 514: static int
1.70 markus 515: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 516: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 517: {
1.58 markus 518: Key *file_key;
1.152 jakob 519: const char *type = key_type(host_key);
1.46 markus 520: char *ip = NULL;
1.100 markus 521: char hostline[1000], *hostp, *fp;
1.38 markus 522: HostStatus host_status;
523: HostStatus ip_status;
1.161 djm 524: int r, local = 0, host_ip_differ = 0;
1.49 markus 525: char ntop[NI_MAXHOST];
1.119 markus 526: char msg[1024];
1.145 jakob 527: int len, host_line, ip_line;
1.85 markus 528: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 529:
530: /*
531: * Force accepting of the host key for loopback/localhost. The
532: * problem is that if the home directory is NFS-mounted to multiple
533: * machines, localhost will refer to a different machine in each of
534: * them, and the user will get bogus HOST_CHANGED warnings. This
535: * essentially disables host authentication for localhost; however,
536: * this is probably not a real problem.
537: */
1.70 markus 538: /** hostaddr == 0! */
1.49 markus 539: switch (hostaddr->sa_family) {
540: case AF_INET:
1.108 markus 541: local = (ntohl(((struct sockaddr_in *)hostaddr)->
1.168 djm 542: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 543: break;
544: case AF_INET6:
1.108 markus 545: local = IN6_IS_ADDR_LOOPBACK(
546: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 547: break;
548: default:
549: local = 0;
550: break;
551: }
1.111 markus 552: if (options.no_host_authentication_for_localhost == 1 && local &&
553: options.host_key_alias == NULL) {
1.88 markus 554: debug("Forcing accepting of host key for "
555: "loopback/localhost.");
1.108 markus 556: return 0;
1.49 markus 557: }
1.42 markus 558:
559: /*
1.88 markus 560: * We don't have the remote ip-address for connections
561: * using a proxy command
1.42 markus 562: */
1.84 markus 563: if (options.proxy_command == NULL) {
564: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 565: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 566: fatal("check_host_key: getnameinfo failed");
567: ip = xstrdup(ntop);
568: } else {
569: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 570: }
1.88 markus 571: /*
572: * Turn off check_host_ip if the connection is to localhost, via proxy
573: * command or if we don't have a hostname to compare with
574: */
575: if (options.check_host_ip &&
576: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
577: options.check_host_ip = 0;
1.86 markus 578:
579: /*
580: * Allow the user to record the key under a different name. This is
581: * useful for ssh tunneling over forwarded connections or if you run
582: * multiple sshd's on different ports on the same machine.
583: */
584: if (options.host_key_alias != NULL) {
585: host = options.host_key_alias;
586: debug("using hostkeyalias: %s", host);
1.84 markus 587: }
1.38 markus 588:
1.46 markus 589: /*
590: * Store the host key from the known host file in here so that we can
591: * compare it with the key for the IP address.
592: */
1.58 markus 593: file_key = key_new(host_key->type);
1.38 markus 594:
1.40 markus 595: /*
1.170 djm 596: * Check if the host key is present in the user's list of known
1.40 markus 597: * hosts or in the systemwide list.
598: */
1.85 markus 599: host_file = user_hostfile;
1.108 markus 600: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 601: file_key, &host_line);
1.85 markus 602: if (host_status == HOST_NEW) {
603: host_file = system_hostfile;
1.108 markus 604: host_status = check_host_in_hostfile(host_file, host, host_key,
605: file_key, &host_line);
1.85 markus 606: }
1.40 markus 607: /*
608: * Also perform check for the ip address, skip the check if we are
609: * localhost or the hostname was an ip address to begin with
610: */
1.88 markus 611: if (options.check_host_ip) {
1.58 markus 612: Key *ip_key = key_new(host_key->type);
1.38 markus 613:
1.85 markus 614: ip_file = user_hostfile;
1.108 markus 615: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
616: ip_key, &ip_line);
1.85 markus 617: if (ip_status == HOST_NEW) {
618: ip_file = system_hostfile;
1.108 markus 619: ip_status = check_host_in_hostfile(ip_file, ip,
620: host_key, ip_key, &ip_line);
1.85 markus 621: }
1.38 markus 622: if (host_status == HOST_CHANGED &&
1.58 markus 623: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 624: host_ip_differ = 1;
625:
1.58 markus 626: key_free(ip_key);
1.38 markus 627: } else
628: ip_status = host_status;
629:
1.58 markus 630: key_free(file_key);
1.38 markus 631:
632: switch (host_status) {
633: case HOST_OK:
634: /* The host is known and the key matches. */
1.72 markus 635: debug("Host '%.200s' is known and matches the %s host key.",
636: host, type);
1.85 markus 637: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 638: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 639: if (readonly)
1.138 itojun 640: logit("%s host key for IP address "
1.108 markus 641: "'%.128s' not in list of known hosts.",
642: type, ip);
643: else if (!add_host_to_hostfile(user_hostfile, ip,
1.160 djm 644: host_key, options.hash_known_hosts))
1.138 itojun 645: logit("Failed to add the %s host key for IP "
1.108 markus 646: "address '%.128s' to the list of known "
647: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 648: else
1.138 itojun 649: logit("Warning: Permanently added the %s host "
1.108 markus 650: "key for IP address '%.128s' to the list "
651: "of known hosts.", type, ip);
1.38 markus 652: }
653: break;
654: case HOST_NEW:
1.108 markus 655: if (readonly)
656: goto fail;
1.38 markus 657: /* The host is new. */
658: if (options.strict_host_key_checking == 1) {
1.108 markus 659: /*
660: * User has requested strict host key checking. We
661: * will not add the host key automatically. The only
662: * alternative left is to abort.
663: */
664: error("No %s host key is known for %.200s and you "
665: "have requested strict checking.", type, host);
666: goto fail;
1.38 markus 667: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 668: char msg1[1024], msg2[1024];
669:
670: if (show_other_keys(host, host_key))
671: snprintf(msg1, sizeof(msg1),
1.168 djm 672: "\nbut keys of different type are already"
673: " known for this host.");
1.145 jakob 674: else
675: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 676: /* The default */
1.100 markus 677: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.145 jakob 678: msg2[0] = '\0';
679: if (options.verify_host_key_dns) {
1.153 jakob 680: if (matching_host_key_dns)
1.145 jakob 681: snprintf(msg2, sizeof(msg2),
682: "Matching host key fingerprint"
683: " found in DNS.\n");
684: else
685: snprintf(msg2, sizeof(msg2),
686: "No matching host key fingerprint"
687: " found in DNS.\n");
688: }
1.119 markus 689: snprintf(msg, sizeof(msg),
1.108 markus 690: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 691: "established%s\n"
1.145 jakob 692: "%s key fingerprint is %s.\n%s"
1.108 markus 693: "Are you sure you want to continue connecting "
1.132 markus 694: "(yes/no)? ",
1.145 jakob 695: host, ip, msg1, type, fp, msg2);
1.100 markus 696: xfree(fp);
1.119 markus 697: if (!confirm(msg))
1.108 markus 698: goto fail;
1.38 markus 699: }
1.161 djm 700: /*
701: * If not in strict mode, add the key automatically to the
702: * local known_hosts file.
703: */
1.88 markus 704: if (options.check_host_ip && ip_status == HOST_NEW) {
1.161 djm 705: snprintf(hostline, sizeof(hostline), "%s,%s",
706: host, ip);
1.38 markus 707: hostp = hostline;
1.161 djm 708: if (options.hash_known_hosts) {
709: /* Add hash of host and IP separately */
710: r = add_host_to_hostfile(user_hostfile, host,
711: host_key, options.hash_known_hosts) &&
712: add_host_to_hostfile(user_hostfile, ip,
713: host_key, options.hash_known_hosts);
714: } else {
715: /* Add unhashed "host,ip" */
716: r = add_host_to_hostfile(user_hostfile,
717: hostline, host_key,
718: options.hash_known_hosts);
719: }
720: } else {
721: r = add_host_to_hostfile(user_hostfile, host, host_key,
722: options.hash_known_hosts);
1.38 markus 723: hostp = host;
1.161 djm 724: }
1.38 markus 725:
1.161 djm 726: if (!r)
1.138 itojun 727: logit("Failed to add the host to the list of known "
1.108 markus 728: "hosts (%.500s).", user_hostfile);
1.38 markus 729: else
1.138 itojun 730: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 731: "list of known hosts.", hostp, type);
1.38 markus 732: break;
733: case HOST_CHANGED:
734: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 735: char *key_msg;
1.38 markus 736: if (ip_status == HOST_NEW)
1.158 avsm 737: key_msg = "is unknown";
1.38 markus 738: else if (ip_status == HOST_OK)
1.158 avsm 739: key_msg = "is unchanged";
1.38 markus 740: else
1.158 avsm 741: key_msg = "has a different value";
1.38 markus 742: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
743: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
744: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 745: error("The %s host key for %s has changed,", type, host);
1.38 markus 746: error("and the key for the according IP address %s", ip);
1.158 avsm 747: error("%s. This could either mean that", key_msg);
1.38 markus 748: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 749: error("and its host key have changed at the same time.");
1.88 markus 750: if (ip_status != HOST_NEW)
1.85 markus 751: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 752: }
753: /* The host key has changed. */
1.150 jakob 754: warn_changed_key(host_key);
1.38 markus 755: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 756: user_hostfile);
1.85 markus 757: error("Offending key in %s:%d", host_file, host_line);
1.38 markus 758:
1.40 markus 759: /*
760: * If strict host key checking is in use, the user will have
761: * to edit the key manually and we can only abort.
762: */
1.108 markus 763: if (options.strict_host_key_checking) {
764: error("%s host key for %.200s has changed and you have "
765: "requested strict checking.", type, host);
766: goto fail;
767: }
1.38 markus 768:
1.40 markus 769: /*
770: * If strict host key checking has not been requested, allow
1.144 djm 771: * the connection but without MITM-able authentication or
1.40 markus 772: * agent forwarding.
773: */
1.38 markus 774: if (options.password_authentication) {
1.108 markus 775: error("Password authentication is disabled to avoid "
776: "man-in-the-middle attacks.");
1.38 markus 777: options.password_authentication = 0;
1.144 djm 778: }
779: if (options.kbd_interactive_authentication) {
780: error("Keyboard-interactive authentication is disabled"
781: " to avoid man-in-the-middle attacks.");
782: options.kbd_interactive_authentication = 0;
783: options.challenge_response_authentication = 0;
784: }
785: if (options.challenge_response_authentication) {
786: error("Challenge/response authentication is disabled"
787: " to avoid man-in-the-middle attacks.");
788: options.challenge_response_authentication = 0;
1.38 markus 789: }
790: if (options.forward_agent) {
1.108 markus 791: error("Agent forwarding is disabled to avoid "
792: "man-in-the-middle attacks.");
1.38 markus 793: options.forward_agent = 0;
1.83 markus 794: }
795: if (options.forward_x11) {
1.108 markus 796: error("X11 forwarding is disabled to avoid "
797: "man-in-the-middle attacks.");
1.83 markus 798: options.forward_x11 = 0;
799: }
1.108 markus 800: if (options.num_local_forwards > 0 ||
801: options.num_remote_forwards > 0) {
802: error("Port forwarding is disabled to avoid "
803: "man-in-the-middle attacks.");
804: options.num_local_forwards =
1.118 deraadt 805: options.num_remote_forwards = 0;
1.38 markus 806: }
1.40 markus 807: /*
808: * XXX Should permit the user to change to use the new id.
809: * This could be done by converting the host key to an
810: * identifying sentence, tell that the host identifies itself
811: * by that sentence, and ask the user if he/she whishes to
812: * accept the authentication.
813: */
1.38 markus 814: break;
1.132 markus 815: case HOST_FOUND:
816: fatal("internal error");
817: break;
1.88 markus 818: }
819:
820: if (options.check_host_ip && host_status != HOST_CHANGED &&
821: ip_status == HOST_CHANGED) {
1.119 markus 822: snprintf(msg, sizeof(msg),
823: "Warning: the %s host key for '%.200s' "
824: "differs from the key for the IP address '%.128s'"
825: "\nOffending key for IP in %s:%d",
826: type, host, ip, ip_file, ip_line);
827: if (host_status == HOST_OK) {
828: len = strlen(msg);
829: snprintf(msg + len, sizeof(msg) - len,
830: "\nMatching host key in %s:%d",
1.125 deraadt 831: host_file, host_line);
1.119 markus 832: }
1.88 markus 833: if (options.strict_host_key_checking == 1) {
1.143 djm 834: logit("%s", msg);
1.108 markus 835: error("Exiting, you have requested strict checking.");
836: goto fail;
1.88 markus 837: } else if (options.strict_host_key_checking == 2) {
1.119 markus 838: strlcat(msg, "\nAre you sure you want "
839: "to continue connecting (yes/no)? ", sizeof(msg));
840: if (!confirm(msg))
1.108 markus 841: goto fail;
1.119 markus 842: } else {
1.143 djm 843: logit("%s", msg);
1.88 markus 844: }
1.38 markus 845: }
1.82 provos 846:
847: xfree(ip);
1.108 markus 848: return 0;
849:
850: fail:
851: xfree(ip);
852: return -1;
853: }
854:
1.140 jakob 855: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 856: int
857: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
858: {
859: struct stat st;
1.153 jakob 860: int flags = 0;
1.140 jakob 861:
1.153 jakob 862: if (options.verify_host_key_dns &&
863: verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
864:
865: if (flags & DNS_VERIFY_FOUND) {
866:
867: if (options.verify_host_key_dns == 1 &&
868: flags & DNS_VERIFY_MATCH &&
869: flags & DNS_VERIFY_SECURE)
870: return 0;
871:
872: if (flags & DNS_VERIFY_MATCH) {
873: matching_host_key_dns = 1;
874: } else {
875: warn_changed_key(host_key);
876: error("Update the SSHFP RR in DNS with the new "
877: "host key to get rid of this message.");
878: }
1.140 jakob 879: }
880: }
1.108 markus 881:
882: /* return ok if the key can be found in an old keyfile */
883: if (stat(options.system_hostfile2, &st) == 0 ||
884: stat(options.user_hostfile2, &st) == 0) {
885: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
886: options.user_hostfile2, options.system_hostfile2) == 0)
887: return 0;
888: }
889: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
890: options.user_hostfile, options.system_hostfile);
1.51 markus 891: }
1.70 markus 892:
1.51 markus 893: /*
894: * Starts a dialog with the server, and authenticates the current user on the
895: * server. This does not need any extra privileges. The basic connection
896: * to the server must already have been established before this is called.
897: * If login fails, this function prints an error and never returns.
898: * This function does not require super-user privileges.
899: */
900: void
1.120 markus 901: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 902: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 903: {
904: char *host, *cp;
1.70 markus 905: char *server_user, *local_user;
906:
907: local_user = xstrdup(pw->pw_name);
908: server_user = options.user ? options.user : local_user;
1.51 markus 909:
910: /* Convert the user-supplied hostname into all lowercase. */
911: host = xstrdup(orighost);
912: for (cp = host; *cp; cp++)
913: if (isupper(*cp))
1.178 deraadt 914: *cp = (char)tolower(*cp);
1.51 markus 915:
916: /* Exchange protocol version identification strings with the server. */
917: ssh_exchange_identification();
918:
919: /* Put the connection into non-blocking mode. */
920: packet_set_nonblocking();
921:
922: /* key exchange */
923: /* authenticate user */
1.59 markus 924: if (compat20) {
925: ssh_kex2(host, hostaddr);
1.120 markus 926: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 927: } else {
928: ssh_kex(host, hostaddr);
1.120 markus 929: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 930: }
1.97 markus 931: }
932:
933: void
934: ssh_put_password(char *password)
935: {
936: int size;
937: char *padded;
938:
1.99 deraadt 939: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 940: packet_put_cstring(password);
1.99 deraadt 941: return;
942: }
1.97 markus 943: size = roundup(strlen(password) + 1, 32);
1.179 ! djm 944: padded = xcalloc(1, size);
1.97 markus 945: strlcpy(padded, password, size);
946: packet_put_string(padded, size);
947: memset(padded, 0, size);
948: xfree(padded);
1.132 markus 949: }
950:
951: static int
952: show_key_from_file(const char *file, const char *host, int keytype)
953: {
954: Key *found;
955: char *fp;
956: int line, ret;
957:
958: found = key_new(keytype);
959: if ((ret = lookup_key_in_hostfile_by_type(file, host,
960: keytype, found, &line))) {
961: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 962: logit("WARNING: %s key found for host %s\n"
1.133 markus 963: "in %s:%d\n"
1.132 markus 964: "%s key fingerprint %s.",
965: key_type(found), host, file, line,
966: key_type(found), fp);
967: xfree(fp);
968: }
969: key_free(found);
970: return (ret);
971: }
972:
973: /* print all known host keys for a given host, but skip keys of given type */
974: static int
975: show_other_keys(const char *host, Key *key)
976: {
977: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
978: int i, found = 0;
979:
980: for (i = 0; type[i] != -1; i++) {
981: if (type[i] == key->type)
982: continue;
983: if (type[i] != KEY_RSA1 &&
984: show_key_from_file(options.user_hostfile2, host, type[i])) {
985: found = 1;
986: continue;
987: }
988: if (type[i] != KEY_RSA1 &&
989: show_key_from_file(options.system_hostfile2, host, type[i])) {
990: found = 1;
991: continue;
992: }
993: if (show_key_from_file(options.user_hostfile, host, type[i])) {
994: found = 1;
995: continue;
996: }
997: if (show_key_from_file(options.system_hostfile, host, type[i])) {
998: found = 1;
999: continue;
1000: }
1001: debug2("no key of type %d for host %s", type[i], host);
1002: }
1003: return (found);
1.150 jakob 1004: }
1005:
1006: static void
1007: warn_changed_key(Key *host_key)
1008: {
1009: char *fp;
1.151 jakob 1010: const char *type = key_type(host_key);
1.150 jakob 1011:
1012: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1013:
1014: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1015: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1016: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1017: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1018: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1019: error("It is also possible that the %s host key has just been changed.", type);
1020: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1021: type, fp);
1022: error("Please contact your system administrator.");
1023:
1024: xfree(fp);
1.171 reyk 1025: }
1026:
1027: /*
1028: * Execute a local command
1029: */
1030: int
1031: ssh_local_cmd(const char *args)
1032: {
1033: char *shell;
1034: pid_t pid;
1035: int status;
1036:
1037: if (!options.permit_local_command ||
1038: args == NULL || !*args)
1039: return (1);
1040:
1041: if ((shell = getenv("SHELL")) == NULL)
1042: shell = _PATH_BSHELL;
1043:
1044: pid = fork();
1045: if (pid == 0) {
1046: debug3("Executing %s -c \"%s\"", shell, args);
1047: execl(shell, shell, "-c", args, (char *)NULL);
1048: error("Couldn't execute %s -c \"%s\": %s",
1049: shell, args, strerror(errno));
1050: _exit(1);
1051: } else if (pid == -1)
1052: fatal("fork failed: %.100s", strerror(errno));
1053: while (waitpid(pid, &status, 0) == -1)
1054: if (errno != EINTR)
1055: fatal("Couldn't wait for child: %s", strerror(errno));
1056:
1057: if (!WIFEXITED(status))
1058: return (1);
1059:
1060: return (WEXITSTATUS(status));
1.1 deraadt 1061: }
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