Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.162.2.1
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"
1.162.2.1! brad 16: RCSID("$OpenBSD: sshconnect.c,v 1.168 2005/07/17 07:17:55 djm Exp $");
1.1 deraadt 17:
1.66 markus 18: #include <openssl/bn.h>
1.71 markus 19:
1.91 markus 20: #include "ssh.h"
1.1 deraadt 21: #include "xmalloc.h"
22: #include "rsa.h"
1.59 markus 23: #include "buffer.h"
1.1 deraadt 24: #include "packet.h"
25: #include "uidswap.h"
1.21 markus 26: #include "compat.h"
1.58 markus 27: #include "key.h"
1.71 markus 28: #include "sshconnect.h"
1.58 markus 29: #include "hostfile.h"
1.91 markus 30: #include "log.h"
31: #include "readconf.h"
32: #include "atomicio.h"
33: #include "misc.h"
1.51 markus 34:
1.140 jakob 35: #include "dns.h"
36:
1.70 markus 37: char *client_version_string = NULL;
38: char *server_version_string = NULL;
1.59 markus 39:
1.153 jakob 40: int matching_host_key_dns = 0;
1.145 jakob 41:
1.124 markus 42: /* import */
1.43 markus 43: extern Options options;
1.50 markus 44: extern char *__progname;
1.124 markus 45: extern uid_t original_real_uid;
46: extern uid_t original_effective_uid;
1.135 djm 47: extern pid_t proxy_command_pid;
1.91 markus 48:
1.132 markus 49: static int show_other_keys(const char *, Key *);
1.150 jakob 50: static void warn_changed_key(Key *);
1.132 markus 51:
1.39 deraadt 52: /*
53: * Connect to the given ssh server using a proxy command.
54: */
1.109 itojun 55: static int
1.124 markus 56: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 57: {
1.162.2.1! brad 58: char *command_string, *tmp;
1.38 markus 59: int pin[2], pout[2];
1.69 deraadt 60: pid_t pid;
1.49 markus 61: char strport[NI_MAXSERV];
1.162.2.1! brad 62: size_t len;
1.38 markus 63:
64: /* Convert the port number into a string. */
1.49 markus 65: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 66:
1.135 djm 67: /*
68: * Build the final command string in the buffer by making the
69: * appropriate substitutions to the given proxy command.
70: *
1.154 djm 71: * Use "exec" to avoid "sh -c" processes on some platforms
1.135 djm 72: * (e.g. Solaris)
73: */
1.162.2.1! brad 74: len = strlen(proxy_command) + 6;
! 75: tmp = xmalloc(len);
! 76: strlcpy(tmp, "exec ", len);
! 77: strlcat(tmp, proxy_command, len);
! 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. */
1.162.2.1! brad 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;
1.142 djm 205: int fdsetsz, 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:
219: fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask);
220: fdset = (fd_set *)xmalloc(fdsetsz);
221:
1.147 markus 222: memset(fdset, 0, fdsetsz);
1.141 djm 223: FD_SET(sockfd, fdset);
224: tv.tv_sec = timeout;
225: tv.tv_usec = 0;
226:
1.162 deraadt 227: for (;;) {
1.141 djm 228: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
229: if (rc != -1 || errno != EINTR)
230: break;
231: }
232:
1.162 deraadt 233: switch (rc) {
1.141 djm 234: case 0:
235: /* Timed out */
236: errno = ETIMEDOUT;
1.142 djm 237: break;
1.141 djm 238: case -1:
239: /* Select error */
1.154 djm 240: debug("select: %s", strerror(errno));
1.142 djm 241: break;
1.141 djm 242: case 1:
243: /* Completed or failed */
244: optval = 0;
245: optlen = sizeof(optval);
1.154 djm 246: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 247: &optlen) == -1) {
1.154 djm 248: debug("getsockopt: %s", strerror(errno));
1.142 djm 249: break;
1.148 markus 250: }
1.141 djm 251: if (optval != 0) {
252: errno = optval;
1.142 djm 253: break;
1.141 djm 254: }
1.142 djm 255: result = 0;
1.156 djm 256: unset_nonblock(sockfd);
1.141 djm 257: break;
258: default:
259: /* Should not occur */
260: fatal("Bogus return (%d) from select()", rc);
261: }
262:
1.142 djm 263: xfree(fdset);
264: return (result);
1.141 djm 265: }
266:
1.39 deraadt 267: /*
1.49 markus 268: * Opens a TCP/IP connection to the remote server on the given host.
269: * The address of the remote host will be returned in hostaddr.
1.124 markus 270: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 271: * a privileged port will be allocated to make the connection.
1.124 markus 272: * This requires super-user privileges if needpriv is true.
1.39 deraadt 273: * Connection_attempts specifies the maximum number of tries (one per
274: * second). If proxy_command is non-NULL, it specifies the command (with %h
275: * and %p substituted for host and port, respectively) to use to contact
276: * the daemon.
277: */
1.38 markus 278: int
1.49 markus 279: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 280: u_short port, int family, int connection_attempts,
1.124 markus 281: int needpriv, const char *proxy_command)
1.1 deraadt 282: {
1.90 markus 283: int gaierr;
284: int on = 1;
1.49 markus 285: int sock = -1, attempt;
1.90 markus 286: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 287: struct addrinfo hints, *ai, *aitop;
1.38 markus 288:
1.136 markus 289: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 290:
291: /* If a proxy command is given, connect using it. */
292: if (proxy_command != NULL)
1.124 markus 293: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 294:
295: /* No proxy command. */
296:
1.49 markus 297: memset(&hints, 0, sizeof(hints));
1.115 markus 298: hints.ai_family = family;
1.49 markus 299: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 300: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 301: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 302: fatal("%s: %.100s: %s", __progname, host,
303: gai_strerror(gaierr));
1.38 markus 304:
1.46 markus 305: /*
306: * Try to connect several times. On some machines, the first time
307: * will sometimes fail. In general socket code appears to behave
308: * quite magically on many machines.
1.110 markus 309: */
310: for (attempt = 0; ;) {
1.38 markus 311: if (attempt > 0)
312: debug("Trying again...");
313:
1.49 markus 314: /* Loop through addresses for this host, and try each one in
1.68 markus 315: sequence until the connection succeeds. */
1.49 markus 316: for (ai = aitop; ai; ai = ai->ai_next) {
317: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
318: continue;
319: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
320: ntop, sizeof(ntop), strport, sizeof(strport),
321: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
322: error("ssh_connect: getnameinfo failed");
323: continue;
324: }
325: debug("Connecting to %.200s [%.100s] port %s.",
326: host, ntop, strport);
327:
328: /* Create a socket for connecting. */
1.139 markus 329: sock = ssh_create_socket(needpriv, ai);
1.49 markus 330: if (sock < 0)
1.110 markus 331: /* Any error is already output */
1.49 markus 332: continue;
333:
1.141 djm 334: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
335: options.connection_timeout) >= 0) {
1.49 markus 336: /* Successful connection. */
1.102 markus 337: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 338: break;
1.49 markus 339: } else {
1.131 itojun 340: debug("connect to address %s port %s: %s",
341: ntop, strport, strerror(errno));
1.40 markus 342: /*
343: * Close the failed socket; there appear to
344: * be some problems when reusing a socket for
345: * which connect() has already returned an
346: * error.
347: */
1.38 markus 348: close(sock);
349: }
350: }
1.49 markus 351: if (ai)
352: break; /* Successful connection. */
1.1 deraadt 353:
1.110 markus 354: attempt++;
355: if (attempt >= connection_attempts)
356: break;
1.38 markus 357: /* Sleep a moment before retrying. */
358: sleep(1);
359: }
1.49 markus 360:
361: freeaddrinfo(aitop);
362:
1.38 markus 363: /* Return failure if we didn't get a successful connection. */
1.130 itojun 364: if (attempt >= connection_attempts) {
1.159 markus 365: error("ssh: connect to host %s port %s: %s",
1.130 itojun 366: host, strport, strerror(errno));
1.159 markus 367: return (-1);
1.130 itojun 368: }
1.38 markus 369:
370: debug("Connection established.");
1.90 markus 371:
1.155 markus 372: /* Set SO_KEEPALIVE if requested. */
373: if (options.tcp_keep_alive &&
1.90 markus 374: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
375: sizeof(on)) < 0)
376: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 377:
378: /* Set the connection. */
379: packet_set_connection(sock, sock);
1.1 deraadt 380:
1.110 markus 381: return 0;
1.59 markus 382: }
383:
1.43 markus 384: /*
1.39 deraadt 385: * Waits for the server identification string, and sends our own
386: * identification string.
387: */
1.109 itojun 388: static void
1.95 itojun 389: ssh_exchange_identification(void)
1.1 deraadt 390: {
1.38 markus 391: char buf[256], remote_version[256]; /* must be same size! */
1.162.2.1! brad 392: int remote_major, remote_minor, mismatch;
1.38 markus 393: int connection_in = packet_get_connection_in();
394: int connection_out = packet_get_connection_out();
1.93 stevesk 395: int minor1 = PROTOCOL_MINOR_1;
1.162.2.1! brad 396: u_int i;
1.38 markus 397:
1.162.2.1! brad 398: /* Read other side's version identification. */
1.75 markus 399: for (;;) {
400: for (i = 0; i < sizeof(buf) - 1; i++) {
1.162.2.1! brad 401: size_t len = atomicio(read, connection_in, &buf[i], 1);
! 402:
! 403: if (len != 1 && errno == EPIPE)
1.75 markus 404: fatal("ssh_exchange_identification: Connection closed by remote host");
1.162.2.1! brad 405: else if (len != 1)
! 406: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
1.75 markus 407: if (buf[i] == '\r') {
408: buf[i] = '\n';
409: buf[i + 1] = 0;
410: continue; /**XXX wait for \n */
411: }
412: if (buf[i] == '\n') {
413: buf[i + 1] = 0;
414: break;
415: }
1.38 markus 416: }
1.75 markus 417: buf[sizeof(buf) - 1] = 0;
1.76 markus 418: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 419: break;
1.75 markus 420: debug("ssh_exchange_identification: %s", buf);
1.38 markus 421: }
1.59 markus 422: server_version_string = xstrdup(buf);
1.38 markus 423:
1.40 markus 424: /*
425: * Check that the versions match. In future this might accept
426: * several versions and set appropriate flags to handle them.
427: */
1.59 markus 428: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
429: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 430: fatal("Bad remote protocol version identification: '%.100s'", buf);
431: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 432: remote_major, remote_minor, remote_version);
1.38 markus 433:
1.59 markus 434: compat_datafellows(remote_version);
1.64 markus 435: mismatch = 0;
1.59 markus 436:
1.116 deraadt 437: switch (remote_major) {
1.64 markus 438: case 1:
439: if (remote_minor == 99 &&
440: (options.protocol & SSH_PROTO_2) &&
441: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
442: enable_compat20();
443: break;
444: }
445: if (!(options.protocol & SSH_PROTO_1)) {
446: mismatch = 1;
447: break;
448: }
449: if (remote_minor < 3) {
450: fatal("Remote machine has too old SSH software version.");
1.81 markus 451: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 452: /* We speak 1.3, too. */
453: enable_compat13();
1.81 markus 454: minor1 = 3;
1.64 markus 455: if (options.forward_agent) {
1.138 itojun 456: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 457: options.forward_agent = 0;
458: }
459: }
460: break;
461: case 2:
462: if (options.protocol & SSH_PROTO_2) {
463: enable_compat20();
464: break;
1.38 markus 465: }
1.64 markus 466: /* FALLTHROUGH */
1.68 markus 467: default:
1.64 markus 468: mismatch = 1;
469: break;
1.38 markus 470: }
1.64 markus 471: if (mismatch)
1.38 markus 472: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 473: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
474: remote_major);
1.38 markus 475: /* Send our own protocol version identification. */
476: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 477: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 478: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 479: SSH_VERSION);
1.146 deraadt 480: if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 481: fatal("write: %.100s", strerror(errno));
1.59 markus 482: client_version_string = xstrdup(buf);
483: chop(client_version_string);
484: chop(server_version_string);
485: debug("Local version string %.100s", client_version_string);
1.1 deraadt 486: }
487:
1.96 markus 488: /* defaults to 'no' */
1.109 itojun 489: static int
1.112 markus 490: confirm(const char *prompt)
1.1 deraadt 491: {
1.119 markus 492: const char *msg, *again = "Please type 'yes' or 'no': ";
493: char *p;
494: int ret = -1;
1.96 markus 495:
496: if (options.batch_mode)
497: return 0;
1.119 markus 498: for (msg = prompt;;msg = again) {
499: p = read_passphrase(msg, RP_ECHO);
500: if (p == NULL ||
501: (p[0] == '\0') || (p[0] == '\n') ||
502: strncasecmp(p, "no", 2) == 0)
503: ret = 0;
1.127 markus 504: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 505: ret = 1;
506: if (p)
507: xfree(p);
508: if (ret != -1)
509: return ret;
1.1 deraadt 510: }
511: }
512:
1.39 deraadt 513: /*
1.108 markus 514: * check whether the supplied host key is valid, return -1 if the key
515: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 516: */
1.109 itojun 517: static int
1.70 markus 518: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 519: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 520: {
1.58 markus 521: Key *file_key;
1.152 jakob 522: const char *type = key_type(host_key);
1.46 markus 523: char *ip = NULL;
1.100 markus 524: char hostline[1000], *hostp, *fp;
1.38 markus 525: HostStatus host_status;
526: HostStatus ip_status;
1.161 djm 527: int r, local = 0, host_ip_differ = 0;
1.49 markus 528: char ntop[NI_MAXHOST];
1.119 markus 529: char msg[1024];
1.145 jakob 530: int len, host_line, ip_line;
1.85 markus 531: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 532:
533: /*
534: * Force accepting of the host key for loopback/localhost. The
535: * problem is that if the home directory is NFS-mounted to multiple
536: * machines, localhost will refer to a different machine in each of
537: * them, and the user will get bogus HOST_CHANGED warnings. This
538: * essentially disables host authentication for localhost; however,
539: * this is probably not a real problem.
540: */
1.70 markus 541: /** hostaddr == 0! */
1.49 markus 542: switch (hostaddr->sa_family) {
543: case AF_INET:
1.108 markus 544: local = (ntohl(((struct sockaddr_in *)hostaddr)->
1.162.2.1! brad 545: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 546: break;
547: case AF_INET6:
1.108 markus 548: local = IN6_IS_ADDR_LOOPBACK(
549: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 550: break;
551: default:
552: local = 0;
553: break;
554: }
1.111 markus 555: if (options.no_host_authentication_for_localhost == 1 && local &&
556: options.host_key_alias == NULL) {
1.88 markus 557: debug("Forcing accepting of host key for "
558: "loopback/localhost.");
1.108 markus 559: return 0;
1.49 markus 560: }
1.42 markus 561:
562: /*
1.88 markus 563: * We don't have the remote ip-address for connections
564: * using a proxy command
1.42 markus 565: */
1.84 markus 566: if (options.proxy_command == NULL) {
567: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 568: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 569: fatal("check_host_key: getnameinfo failed");
570: ip = xstrdup(ntop);
571: } else {
572: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 573: }
1.88 markus 574: /*
575: * Turn off check_host_ip if the connection is to localhost, via proxy
576: * command or if we don't have a hostname to compare with
577: */
578: if (options.check_host_ip &&
579: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
580: options.check_host_ip = 0;
1.86 markus 581:
582: /*
583: * Allow the user to record the key under a different name. This is
584: * useful for ssh tunneling over forwarded connections or if you run
585: * multiple sshd's on different ports on the same machine.
586: */
587: if (options.host_key_alias != NULL) {
588: host = options.host_key_alias;
589: debug("using hostkeyalias: %s", host);
1.84 markus 590: }
1.38 markus 591:
1.46 markus 592: /*
593: * Store the host key from the known host file in here so that we can
594: * compare it with the key for the IP address.
595: */
1.58 markus 596: file_key = key_new(host_key->type);
1.38 markus 597:
1.40 markus 598: /*
599: * Check if the host key is present in the user\'s list of known
600: * hosts or in the systemwide list.
601: */
1.85 markus 602: host_file = user_hostfile;
1.108 markus 603: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 604: file_key, &host_line);
1.85 markus 605: if (host_status == HOST_NEW) {
606: host_file = system_hostfile;
1.108 markus 607: host_status = check_host_in_hostfile(host_file, host, host_key,
608: file_key, &host_line);
1.85 markus 609: }
1.40 markus 610: /*
611: * Also perform check for the ip address, skip the check if we are
612: * localhost or the hostname was an ip address to begin with
613: */
1.88 markus 614: if (options.check_host_ip) {
1.58 markus 615: Key *ip_key = key_new(host_key->type);
1.38 markus 616:
1.85 markus 617: ip_file = user_hostfile;
1.108 markus 618: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
619: ip_key, &ip_line);
1.85 markus 620: if (ip_status == HOST_NEW) {
621: ip_file = system_hostfile;
1.108 markus 622: ip_status = check_host_in_hostfile(ip_file, ip,
623: host_key, ip_key, &ip_line);
1.85 markus 624: }
1.38 markus 625: if (host_status == HOST_CHANGED &&
1.58 markus 626: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 627: host_ip_differ = 1;
628:
1.58 markus 629: key_free(ip_key);
1.38 markus 630: } else
631: ip_status = host_status;
632:
1.58 markus 633: key_free(file_key);
1.38 markus 634:
635: switch (host_status) {
636: case HOST_OK:
637: /* The host is known and the key matches. */
1.72 markus 638: debug("Host '%.200s' is known and matches the %s host key.",
639: host, type);
1.85 markus 640: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 641: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 642: if (readonly)
1.138 itojun 643: logit("%s host key for IP address "
1.108 markus 644: "'%.128s' not in list of known hosts.",
645: type, ip);
646: else if (!add_host_to_hostfile(user_hostfile, ip,
1.160 djm 647: host_key, options.hash_known_hosts))
1.138 itojun 648: logit("Failed to add the %s host key for IP "
1.108 markus 649: "address '%.128s' to the list of known "
650: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 651: else
1.138 itojun 652: logit("Warning: Permanently added the %s host "
1.108 markus 653: "key for IP address '%.128s' to the list "
654: "of known hosts.", type, ip);
1.38 markus 655: }
656: break;
657: case HOST_NEW:
1.108 markus 658: if (readonly)
659: goto fail;
1.38 markus 660: /* The host is new. */
661: if (options.strict_host_key_checking == 1) {
1.108 markus 662: /*
663: * User has requested strict host key checking. We
664: * will not add the host key automatically. The only
665: * alternative left is to abort.
666: */
667: error("No %s host key is known for %.200s and you "
668: "have requested strict checking.", type, host);
669: goto fail;
1.38 markus 670: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 671: char msg1[1024], msg2[1024];
672:
673: if (show_other_keys(host, host_key))
674: snprintf(msg1, sizeof(msg1),
1.162.2.1! brad 675: "\nbut keys of different type are already"
! 676: " known for this host.");
1.145 jakob 677: else
678: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 679: /* The default */
1.100 markus 680: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.145 jakob 681: msg2[0] = '\0';
682: if (options.verify_host_key_dns) {
1.153 jakob 683: if (matching_host_key_dns)
1.145 jakob 684: snprintf(msg2, sizeof(msg2),
685: "Matching host key fingerprint"
686: " found in DNS.\n");
687: else
688: snprintf(msg2, sizeof(msg2),
689: "No matching host key fingerprint"
690: " found in DNS.\n");
691: }
1.119 markus 692: snprintf(msg, sizeof(msg),
1.108 markus 693: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 694: "established%s\n"
1.145 jakob 695: "%s key fingerprint is %s.\n%s"
1.108 markus 696: "Are you sure you want to continue connecting "
1.132 markus 697: "(yes/no)? ",
1.145 jakob 698: host, ip, msg1, type, fp, msg2);
1.100 markus 699: xfree(fp);
1.119 markus 700: if (!confirm(msg))
1.108 markus 701: goto fail;
1.38 markus 702: }
1.161 djm 703: /*
704: * If not in strict mode, add the key automatically to the
705: * local known_hosts file.
706: */
1.88 markus 707: if (options.check_host_ip && ip_status == HOST_NEW) {
1.161 djm 708: snprintf(hostline, sizeof(hostline), "%s,%s",
709: host, ip);
1.38 markus 710: hostp = hostline;
1.161 djm 711: if (options.hash_known_hosts) {
712: /* Add hash of host and IP separately */
713: r = add_host_to_hostfile(user_hostfile, host,
714: host_key, options.hash_known_hosts) &&
715: add_host_to_hostfile(user_hostfile, ip,
716: host_key, options.hash_known_hosts);
717: } else {
718: /* Add unhashed "host,ip" */
719: r = add_host_to_hostfile(user_hostfile,
720: hostline, host_key,
721: options.hash_known_hosts);
722: }
723: } else {
724: r = add_host_to_hostfile(user_hostfile, host, host_key,
725: options.hash_known_hosts);
1.38 markus 726: hostp = host;
1.161 djm 727: }
1.38 markus 728:
1.161 djm 729: if (!r)
1.138 itojun 730: logit("Failed to add the host to the list of known "
1.108 markus 731: "hosts (%.500s).", user_hostfile);
1.38 markus 732: else
1.138 itojun 733: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 734: "list of known hosts.", hostp, type);
1.38 markus 735: break;
736: case HOST_CHANGED:
737: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 738: char *key_msg;
1.38 markus 739: if (ip_status == HOST_NEW)
1.158 avsm 740: key_msg = "is unknown";
1.38 markus 741: else if (ip_status == HOST_OK)
1.158 avsm 742: key_msg = "is unchanged";
1.38 markus 743: else
1.158 avsm 744: key_msg = "has a different value";
1.38 markus 745: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
746: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
747: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 748: error("The %s host key for %s has changed,", type, host);
1.38 markus 749: error("and the key for the according IP address %s", ip);
1.158 avsm 750: error("%s. This could either mean that", key_msg);
1.38 markus 751: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 752: error("and its host key have changed at the same time.");
1.88 markus 753: if (ip_status != HOST_NEW)
1.85 markus 754: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 755: }
756: /* The host key has changed. */
1.150 jakob 757: warn_changed_key(host_key);
1.38 markus 758: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 759: user_hostfile);
1.85 markus 760: error("Offending key in %s:%d", host_file, host_line);
1.38 markus 761:
1.40 markus 762: /*
763: * If strict host key checking is in use, the user will have
764: * to edit the key manually and we can only abort.
765: */
1.108 markus 766: if (options.strict_host_key_checking) {
767: error("%s host key for %.200s has changed and you have "
768: "requested strict checking.", type, host);
769: goto fail;
770: }
1.38 markus 771:
1.40 markus 772: /*
773: * If strict host key checking has not been requested, allow
1.144 djm 774: * the connection but without MITM-able authentication or
1.40 markus 775: * agent forwarding.
776: */
1.38 markus 777: if (options.password_authentication) {
1.108 markus 778: error("Password authentication is disabled to avoid "
779: "man-in-the-middle attacks.");
1.38 markus 780: options.password_authentication = 0;
1.144 djm 781: }
782: if (options.kbd_interactive_authentication) {
783: error("Keyboard-interactive authentication is disabled"
784: " to avoid man-in-the-middle attacks.");
785: options.kbd_interactive_authentication = 0;
786: options.challenge_response_authentication = 0;
787: }
788: if (options.challenge_response_authentication) {
789: error("Challenge/response authentication is disabled"
790: " to avoid man-in-the-middle attacks.");
791: options.challenge_response_authentication = 0;
1.38 markus 792: }
793: if (options.forward_agent) {
1.108 markus 794: error("Agent forwarding is disabled to avoid "
795: "man-in-the-middle attacks.");
1.38 markus 796: options.forward_agent = 0;
1.83 markus 797: }
798: if (options.forward_x11) {
1.108 markus 799: error("X11 forwarding is disabled to avoid "
800: "man-in-the-middle attacks.");
1.83 markus 801: options.forward_x11 = 0;
802: }
1.108 markus 803: if (options.num_local_forwards > 0 ||
804: options.num_remote_forwards > 0) {
805: error("Port forwarding is disabled to avoid "
806: "man-in-the-middle attacks.");
807: options.num_local_forwards =
1.118 deraadt 808: options.num_remote_forwards = 0;
1.38 markus 809: }
1.40 markus 810: /*
811: * XXX Should permit the user to change to use the new id.
812: * This could be done by converting the host key to an
813: * identifying sentence, tell that the host identifies itself
814: * by that sentence, and ask the user if he/she whishes to
815: * accept the authentication.
816: */
1.38 markus 817: break;
1.132 markus 818: case HOST_FOUND:
819: fatal("internal error");
820: break;
1.88 markus 821: }
822:
823: if (options.check_host_ip && host_status != HOST_CHANGED &&
824: ip_status == HOST_CHANGED) {
1.119 markus 825: snprintf(msg, sizeof(msg),
826: "Warning: the %s host key for '%.200s' "
827: "differs from the key for the IP address '%.128s'"
828: "\nOffending key for IP in %s:%d",
829: type, host, ip, ip_file, ip_line);
830: if (host_status == HOST_OK) {
831: len = strlen(msg);
832: snprintf(msg + len, sizeof(msg) - len,
833: "\nMatching host key in %s:%d",
1.125 deraadt 834: host_file, host_line);
1.119 markus 835: }
1.88 markus 836: if (options.strict_host_key_checking == 1) {
1.143 djm 837: logit("%s", msg);
1.108 markus 838: error("Exiting, you have requested strict checking.");
839: goto fail;
1.88 markus 840: } else if (options.strict_host_key_checking == 2) {
1.119 markus 841: strlcat(msg, "\nAre you sure you want "
842: "to continue connecting (yes/no)? ", sizeof(msg));
843: if (!confirm(msg))
1.108 markus 844: goto fail;
1.119 markus 845: } else {
1.143 djm 846: logit("%s", msg);
1.88 markus 847: }
1.38 markus 848: }
1.82 provos 849:
850: xfree(ip);
1.108 markus 851: return 0;
852:
853: fail:
854: xfree(ip);
855: return -1;
856: }
857:
1.140 jakob 858: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 859: int
860: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
861: {
862: struct stat st;
1.153 jakob 863: int flags = 0;
1.140 jakob 864:
1.153 jakob 865: if (options.verify_host_key_dns &&
866: verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
867:
868: if (flags & DNS_VERIFY_FOUND) {
869:
870: if (options.verify_host_key_dns == 1 &&
871: flags & DNS_VERIFY_MATCH &&
872: flags & DNS_VERIFY_SECURE)
873: return 0;
874:
875: if (flags & DNS_VERIFY_MATCH) {
876: matching_host_key_dns = 1;
877: } else {
878: warn_changed_key(host_key);
879: error("Update the SSHFP RR in DNS with the new "
880: "host key to get rid of this message.");
881: }
1.140 jakob 882: }
883: }
1.108 markus 884:
885: /* return ok if the key can be found in an old keyfile */
886: if (stat(options.system_hostfile2, &st) == 0 ||
887: stat(options.user_hostfile2, &st) == 0) {
888: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
889: options.user_hostfile2, options.system_hostfile2) == 0)
890: return 0;
891: }
892: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
893: options.user_hostfile, options.system_hostfile);
1.51 markus 894: }
1.70 markus 895:
1.51 markus 896: /*
897: * Starts a dialog with the server, and authenticates the current user on the
898: * server. This does not need any extra privileges. The basic connection
899: * to the server must already have been established before this is called.
900: * If login fails, this function prints an error and never returns.
901: * This function does not require super-user privileges.
902: */
903: void
1.120 markus 904: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 905: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 906: {
907: char *host, *cp;
1.70 markus 908: char *server_user, *local_user;
909:
910: local_user = xstrdup(pw->pw_name);
911: server_user = options.user ? options.user : local_user;
1.51 markus 912:
913: /* Convert the user-supplied hostname into all lowercase. */
914: host = xstrdup(orighost);
915: for (cp = host; *cp; cp++)
916: if (isupper(*cp))
917: *cp = tolower(*cp);
918:
919: /* Exchange protocol version identification strings with the server. */
920: ssh_exchange_identification();
921:
922: /* Put the connection into non-blocking mode. */
923: packet_set_nonblocking();
924:
925: /* key exchange */
926: /* authenticate user */
1.59 markus 927: if (compat20) {
928: ssh_kex2(host, hostaddr);
1.120 markus 929: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 930: } else {
931: ssh_kex(host, hostaddr);
1.120 markus 932: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 933: }
1.97 markus 934: }
935:
936: void
937: ssh_put_password(char *password)
938: {
939: int size;
940: char *padded;
941:
1.99 deraadt 942: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 943: packet_put_cstring(password);
1.99 deraadt 944: return;
945: }
1.97 markus 946: size = roundup(strlen(password) + 1, 32);
947: padded = xmalloc(size);
948: memset(padded, 0, size);
949: strlcpy(padded, password, size);
950: packet_put_string(padded, size);
951: memset(padded, 0, size);
952: xfree(padded);
1.132 markus 953: }
954:
955: static int
956: show_key_from_file(const char *file, const char *host, int keytype)
957: {
958: Key *found;
959: char *fp;
960: int line, ret;
961:
962: found = key_new(keytype);
963: if ((ret = lookup_key_in_hostfile_by_type(file, host,
964: keytype, found, &line))) {
965: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 966: logit("WARNING: %s key found for host %s\n"
1.133 markus 967: "in %s:%d\n"
1.132 markus 968: "%s key fingerprint %s.",
969: key_type(found), host, file, line,
970: key_type(found), fp);
971: xfree(fp);
972: }
973: key_free(found);
974: return (ret);
975: }
976:
977: /* print all known host keys for a given host, but skip keys of given type */
978: static int
979: show_other_keys(const char *host, Key *key)
980: {
981: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
982: int i, found = 0;
983:
984: for (i = 0; type[i] != -1; i++) {
985: if (type[i] == key->type)
986: continue;
987: if (type[i] != KEY_RSA1 &&
988: show_key_from_file(options.user_hostfile2, host, type[i])) {
989: found = 1;
990: continue;
991: }
992: if (type[i] != KEY_RSA1 &&
993: show_key_from_file(options.system_hostfile2, host, type[i])) {
994: found = 1;
995: continue;
996: }
997: if (show_key_from_file(options.user_hostfile, host, type[i])) {
998: found = 1;
999: continue;
1000: }
1001: if (show_key_from_file(options.system_hostfile, host, type[i])) {
1002: found = 1;
1003: continue;
1004: }
1005: debug2("no key of type %d for host %s", type[i], host);
1006: }
1007: return (found);
1.150 jakob 1008: }
1009:
1010: static void
1011: warn_changed_key(Key *host_key)
1012: {
1013: char *fp;
1.151 jakob 1014: const char *type = key_type(host_key);
1.150 jakob 1015:
1016: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1017:
1018: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1019: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1020: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1021: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1022: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1023: error("It is also possible that the %s host key has just been changed.", type);
1024: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1025: type, fp);
1026: error("Please contact your system administrator.");
1027:
1028: xfree(fp);
1.1 deraadt 1029: }
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