Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.79.2.5
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"
1.79.2.5! miod 16: RCSID("$OpenBSD: sshconnect.c,v 1.110 2001/07/25 14:35:18 markus Exp $");
1.1 deraadt 17:
1.66 markus 18: #include <openssl/bn.h>
1.71 markus 19:
1.79.2.1 jason 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"
1.79.2.1 jason 30: #include "log.h"
31: #include "readconf.h"
32: #include "atomicio.h"
33: #include "misc.h"
1.51 markus 34:
1.70 markus 35: char *client_version_string = NULL;
36: char *server_version_string = NULL;
1.59 markus 37:
1.43 markus 38: extern Options options;
1.50 markus 39: extern char *__progname;
1.43 markus 40:
1.79.2.1 jason 41: /* AF_UNSPEC or AF_INET or AF_INET6 */
42: extern int IPv4or6;
43:
1.79.2.5! miod 44: static const char *
! 45: sockaddr_ntop(struct sockaddr *sa)
! 46: {
! 47: void *addr;
! 48: static char addrbuf[INET6_ADDRSTRLEN];
! 49:
! 50: switch (sa->sa_family) {
! 51: case AF_INET:
! 52: addr = &((struct sockaddr_in *)sa)->sin_addr;
! 53: break;
! 54: case AF_INET6:
! 55: addr = &((struct sockaddr_in6 *)sa)->sin6_addr;
! 56: break;
! 57: default:
! 58: /* This case should be protected against elsewhere */
! 59: abort();
! 60: }
! 61: inet_ntop(sa->sa_family, addr, addrbuf, sizeof(addrbuf));
! 62: return addrbuf;
! 63: }
! 64:
1.39 deraadt 65: /*
66: * Connect to the given ssh server using a proxy command.
67: */
1.79.2.5! miod 68: static int
1.79.2.4 jason 69: ssh_proxy_connect(const char *host, u_short port, struct passwd *pw,
1.3 provos 70: const char *proxy_command)
1.1 deraadt 71: {
1.38 markus 72: Buffer command;
73: const char *cp;
74: char *command_string;
75: int pin[2], pout[2];
1.69 deraadt 76: pid_t pid;
1.49 markus 77: char strport[NI_MAXSERV];
1.38 markus 78:
79: /* Convert the port number into a string. */
1.49 markus 80: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 81:
82: /* Build the final command string in the buffer by making the
83: appropriate substitutions to the given proxy command. */
84: buffer_init(&command);
85: for (cp = proxy_command; *cp; cp++) {
86: if (cp[0] == '%' && cp[1] == '%') {
87: buffer_append(&command, "%", 1);
88: cp++;
89: continue;
90: }
91: if (cp[0] == '%' && cp[1] == 'h') {
92: buffer_append(&command, host, strlen(host));
93: cp++;
94: continue;
95: }
96: if (cp[0] == '%' && cp[1] == 'p') {
1.49 markus 97: buffer_append(&command, strport, strlen(strport));
1.38 markus 98: cp++;
99: continue;
100: }
101: buffer_append(&command, cp, 1);
102: }
103: buffer_append(&command, "\0", 1);
104:
105: /* Get the final command string. */
106: command_string = buffer_ptr(&command);
107:
108: /* Create pipes for communicating with the proxy. */
109: if (pipe(pin) < 0 || pipe(pout) < 0)
110: fatal("Could not create pipes to communicate with the proxy: %.100s",
111: strerror(errno));
112:
113: debug("Executing proxy command: %.500s", command_string);
114:
115: /* Fork and execute the proxy command. */
116: if ((pid = fork()) == 0) {
117: char *argv[10];
118:
119: /* Child. Permanently give up superuser privileges. */
1.79.2.4 jason 120: permanently_set_uid(pw);
1.38 markus 121:
122: /* Redirect stdin and stdout. */
123: close(pin[1]);
124: if (pin[0] != 0) {
125: if (dup2(pin[0], 0) < 0)
126: perror("dup2 stdin");
127: close(pin[0]);
128: }
129: close(pout[0]);
130: if (dup2(pout[1], 1) < 0)
131: perror("dup2 stdout");
132: /* Cannot be 1 because pin allocated two descriptors. */
133: close(pout[1]);
134:
135: /* Stderr is left as it is so that error messages get
136: printed on the user's terminal. */
1.79.2.1 jason 137: argv[0] = _PATH_BSHELL;
1.38 markus 138: argv[1] = "-c";
139: argv[2] = command_string;
140: argv[3] = NULL;
141:
142: /* Execute the proxy command. Note that we gave up any
143: extra privileges above. */
1.79.2.1 jason 144: execv(argv[0], argv);
145: perror(argv[0]);
1.38 markus 146: exit(1);
147: }
148: /* Parent. */
149: if (pid < 0)
150: fatal("fork failed: %.100s", strerror(errno));
151:
152: /* Close child side of the descriptors. */
153: close(pin[0]);
154: close(pout[1]);
155:
156: /* Free the command name. */
157: buffer_free(&command);
158:
159: /* Set the connection file descriptors. */
160: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 161:
1.79.2.5! miod 162: /* Indicate OK return */
! 163: return 0;
1.1 deraadt 164: }
165:
1.39 deraadt 166: /*
167: * Creates a (possibly privileged) socket for use as the ssh connection.
168: */
1.79.2.5! miod 169: static int
1.79.2.4 jason 170: ssh_create_socket(struct passwd *pw, int privileged, int family)
1.1 deraadt 171: {
1.79.2.5! miod 172: int sock, gaierr;
! 173: struct addrinfo hints, *res;
1.1 deraadt 174:
1.40 markus 175: /*
176: * If we are running as root and want to connect to a privileged
177: * port, bind our own socket to a privileged port.
178: */
1.38 markus 179: if (privileged) {
180: int p = IPPORT_RESERVED - 1;
1.49 markus 181: sock = rresvport_af(&p, family);
1.38 markus 182: if (sock < 0)
1.55 markus 183: error("rresvport: af=%d %.100s", family, strerror(errno));
184: else
185: debug("Allocated local port %d.", p);
1.79.2.5! miod 186: return sock;
1.38 markus 187: }
1.79.2.5! miod 188: /*
! 189: * Just create an ordinary socket on arbitrary port. We use
! 190: * the user's uid to create the socket.
! 191: */
! 192: temporarily_use_uid(pw);
! 193: sock = socket(family, SOCK_STREAM, 0);
! 194: if (sock < 0)
! 195: error("socket: %.100s", strerror(errno));
! 196: restore_uid();
! 197:
! 198: /* Bind the socket to an alternative local IP address */
! 199: if (options.bind_address == NULL)
! 200: return sock;
! 201:
! 202: memset(&hints, 0, sizeof(hints));
! 203: hints.ai_family = IPv4or6;
! 204: hints.ai_socktype = SOCK_STREAM;
! 205: hints.ai_flags = AI_PASSIVE;
! 206: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
! 207: if (gaierr) {
! 208: error("getaddrinfo: %s: %s", options.bind_address,
! 209: gai_strerror(gaierr));
! 210: close(sock);
! 211: return -1;
! 212: }
! 213: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
! 214: error("bind: %s: %s", options.bind_address, strerror(errno));
! 215: close(sock);
! 216: freeaddrinfo(res);
! 217: return -1;
! 218: }
! 219: freeaddrinfo(res);
1.38 markus 220: return sock;
1.1 deraadt 221: }
222:
1.39 deraadt 223: /*
1.49 markus 224: * Opens a TCP/IP connection to the remote server on the given host.
225: * The address of the remote host will be returned in hostaddr.
226: * If port is 0, the default port will be used. If anonymous is zero,
1.39 deraadt 227: * a privileged port will be allocated to make the connection.
228: * This requires super-user privileges if anonymous is false.
229: * Connection_attempts specifies the maximum number of tries (one per
230: * second). If proxy_command is non-NULL, it specifies the command (with %h
231: * and %p substituted for host and port, respectively) to use to contact
232: * the daemon.
1.79.2.5! miod 233: * Return values:
! 234: * 0 for OK
! 235: * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
! 236: * ECONNABORTED if we failed without a "Connection refused"
! 237: * Suitable error messages for the connection failure will already have been
! 238: * printed.
1.39 deraadt 239: */
1.38 markus 240: int
1.49 markus 241: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.41 markus 242: u_short port, int connection_attempts,
1.79.2.4 jason 243: int anonymous, struct passwd *pw,
1.38 markus 244: const char *proxy_command)
1.1 deraadt 245: {
1.79.2.1 jason 246: int gaierr;
247: int on = 1;
1.49 markus 248: int sock = -1, attempt;
249: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.79.2.1 jason 250: struct addrinfo hints, *ai, *aitop;
1.38 markus 251: struct linger linger;
1.79.2.1 jason 252: struct servent *sp;
1.79.2.5! miod 253: /*
! 254: * Did we get only other errors than "Connection refused" (which
! 255: * should block fallback to rsh and similar), or did we get at least
! 256: * one "Connection refused"?
! 257: */
! 258: int full_failure = 1;
1.38 markus 259:
1.77 deraadt 260: debug("ssh_connect: getuid %u geteuid %u anon %d",
261: (u_int) getuid(), (u_int) geteuid(), anonymous);
1.38 markus 262:
263: /* Get default port if port has not been set. */
264: if (port == 0) {
265: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
266: if (sp)
267: port = ntohs(sp->s_port);
268: else
269: port = SSH_DEFAULT_PORT;
270: }
271: /* If a proxy command is given, connect using it. */
272: if (proxy_command != NULL)
1.79.2.4 jason 273: return ssh_proxy_connect(host, port, pw, proxy_command);
1.38 markus 274:
275: /* No proxy command. */
276:
1.49 markus 277: memset(&hints, 0, sizeof(hints));
278: hints.ai_family = IPv4or6;
279: hints.ai_socktype = SOCK_STREAM;
280: snprintf(strport, sizeof strport, "%d", port);
281: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 282: fatal("%s: %.100s: %s", __progname, host,
283: gai_strerror(gaierr));
1.38 markus 284:
1.46 markus 285: /*
286: * Try to connect several times. On some machines, the first time
287: * will sometimes fail. In general socket code appears to behave
288: * quite magically on many machines.
1.79.2.5! miod 289: */
! 290: for (attempt = 0; ;) {
1.38 markus 291: if (attempt > 0)
292: debug("Trying again...");
293:
1.49 markus 294: /* Loop through addresses for this host, and try each one in
1.68 markus 295: sequence until the connection succeeds. */
1.49 markus 296: for (ai = aitop; ai; ai = ai->ai_next) {
297: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
298: continue;
299: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
300: ntop, sizeof(ntop), strport, sizeof(strport),
301: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
302: error("ssh_connect: getnameinfo failed");
303: continue;
304: }
305: debug("Connecting to %.200s [%.100s] port %s.",
306: host, ntop, strport);
307:
308: /* Create a socket for connecting. */
1.79.2.4 jason 309: sock = ssh_create_socket(pw,
1.79.2.1 jason 310: !anonymous && geteuid() == 0,
1.49 markus 311: ai->ai_family);
312: if (sock < 0)
1.79.2.5! miod 313: /* Any error is already output */
1.49 markus 314: continue;
315:
316: /* Connect to the host. We use the user's uid in the
317: * hope that it will help with tcp_wrappers showing
318: * the remote uid as root.
1.40 markus 319: */
1.79.2.4 jason 320: temporarily_use_uid(pw);
1.49 markus 321: if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
322: /* Successful connection. */
1.79.2.4 jason 323: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 324: restore_uid();
325: break;
1.49 markus 326: } else {
1.79.2.5! miod 327: if (errno == ECONNREFUSED)
! 328: full_failure = 0;
! 329: log("ssh: connect to address %s port %s: %s",
! 330: sockaddr_ntop(ai->ai_addr), strport,
! 331: strerror(errno));
1.38 markus 332: restore_uid();
1.40 markus 333: /*
334: * Close the failed socket; there appear to
335: * be some problems when reusing a socket for
336: * which connect() has already returned an
337: * error.
338: */
1.38 markus 339: shutdown(sock, SHUT_RDWR);
340: close(sock);
341: }
342: }
1.49 markus 343: if (ai)
344: break; /* Successful connection. */
1.1 deraadt 345:
1.79.2.5! miod 346: attempt++;
! 347: if (attempt >= connection_attempts)
! 348: break;
1.38 markus 349: /* Sleep a moment before retrying. */
350: sleep(1);
351: }
1.49 markus 352:
353: freeaddrinfo(aitop);
354:
1.38 markus 355: /* Return failure if we didn't get a successful connection. */
356: if (attempt >= connection_attempts)
1.79.2.5! miod 357: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.38 markus 358:
359: debug("Connection established.");
360:
1.40 markus 361: /*
362: * Set socket options. We would like the socket to disappear as soon
363: * as it has been closed for whatever reason.
364: */
365: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.38 markus 366: linger.l_onoff = 1;
367: linger.l_linger = 5;
1.79.2.1 jason 368: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
369:
370: /* Set keepalives if requested. */
371: if (options.keepalives &&
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:
1.79.2.5! miod 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: */
1.79.2.5! miod 386: static void
1.79.2.1 jason 387: ssh_exchange_identification(void)
1.1 deraadt 388: {
1.38 markus 389: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 390: int remote_major, remote_minor, i, mismatch;
1.38 markus 391: int connection_in = packet_get_connection_in();
392: int connection_out = packet_get_connection_out();
1.79.2.1 jason 393: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 394:
395: /* Read other side\'s version identification. */
1.75 markus 396: for (;;) {
397: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 398: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 399: if (len < 0)
400: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
401: if (len != 1)
402: fatal("ssh_exchange_identification: Connection closed by remote host");
403: if (buf[i] == '\r') {
404: buf[i] = '\n';
405: buf[i + 1] = 0;
406: continue; /**XXX wait for \n */
407: }
408: if (buf[i] == '\n') {
409: buf[i + 1] = 0;
410: break;
411: }
1.38 markus 412: }
1.75 markus 413: buf[sizeof(buf) - 1] = 0;
1.76 markus 414: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 415: break;
1.75 markus 416: debug("ssh_exchange_identification: %s", buf);
1.38 markus 417: }
1.59 markus 418: server_version_string = xstrdup(buf);
1.38 markus 419:
1.40 markus 420: /*
421: * Check that the versions match. In future this might accept
422: * several versions and set appropriate flags to handle them.
423: */
1.59 markus 424: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
425: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 426: fatal("Bad remote protocol version identification: '%.100s'", buf);
427: debug("Remote protocol version %d.%d, remote software version %.100s",
428: remote_major, remote_minor, remote_version);
429:
1.59 markus 430: compat_datafellows(remote_version);
1.64 markus 431: mismatch = 0;
1.59 markus 432:
1.64 markus 433: switch(remote_major) {
434: case 1:
435: if (remote_minor == 99 &&
436: (options.protocol & SSH_PROTO_2) &&
437: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
438: enable_compat20();
439: break;
440: }
441: if (!(options.protocol & SSH_PROTO_1)) {
442: mismatch = 1;
443: break;
444: }
445: if (remote_minor < 3) {
446: fatal("Remote machine has too old SSH software version.");
1.79.2.1 jason 447: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 448: /* We speak 1.3, too. */
449: enable_compat13();
1.79.2.1 jason 450: minor1 = 3;
1.64 markus 451: if (options.forward_agent) {
452: log("Agent forwarding disabled for protocol 1.3");
453: options.forward_agent = 0;
454: }
455: }
456: break;
457: case 2:
458: if (options.protocol & SSH_PROTO_2) {
459: enable_compat20();
460: break;
1.38 markus 461: }
1.64 markus 462: /* FALLTHROUGH */
1.68 markus 463: default:
1.64 markus 464: mismatch = 1;
465: break;
1.38 markus 466: }
1.64 markus 467: if (mismatch)
1.38 markus 468: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 469: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
470: remote_major);
1.38 markus 471: /* Send our own protocol version identification. */
472: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 473: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.79.2.1 jason 474: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 475: SSH_VERSION);
1.45 deraadt 476: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 477: fatal("write: %.100s", strerror(errno));
1.59 markus 478: client_version_string = xstrdup(buf);
479: chop(client_version_string);
480: chop(server_version_string);
481: debug("Local version string %.100s", client_version_string);
1.1 deraadt 482: }
483:
1.79.2.1 jason 484: /* defaults to 'no' */
1.79.2.5! miod 485: static int
1.38 markus 486: read_yes_or_no(const char *prompt, int defval)
1.1 deraadt 487: {
1.38 markus 488: char buf[1024];
489: FILE *f;
490: int retval = -1;
491:
1.79.2.1 jason 492: if (options.batch_mode)
493: return 0;
494:
495: if (isatty(STDIN_FILENO))
1.38 markus 496: f = stdin;
497: else
1.79.2.1 jason 498: f = fopen(_PATH_TTY, "rw");
1.38 markus 499:
500: if (f == NULL)
501: return 0;
502:
503: fflush(stdout);
504:
505: while (1) {
506: fprintf(stderr, "%s", prompt);
507: if (fgets(buf, sizeof(buf), f) == NULL) {
1.79.2.5! miod 508: /*
! 509: * Print a newline (the prompt probably didn\'t have
! 510: * one).
! 511: */
1.38 markus 512: fprintf(stderr, "\n");
513: strlcpy(buf, "no", sizeof buf);
514: }
515: /* Remove newline from response. */
516: if (strchr(buf, '\n'))
517: *strchr(buf, '\n') = 0;
518:
519: if (buf[0] == 0)
520: retval = defval;
521: if (strcmp(buf, "yes") == 0)
522: retval = 1;
1.79 markus 523: else if (strcmp(buf, "no") == 0)
1.38 markus 524: retval = 0;
1.79 markus 525: else
526: fprintf(stderr, "Please type 'yes' or 'no'.\n");
1.38 markus 527:
528: if (retval != -1) {
529: if (f != stdin)
530: fclose(f);
531: return retval;
532: }
1.1 deraadt 533: }
534: }
535:
1.39 deraadt 536: /*
1.79.2.5! miod 537: * check whether the supplied host key is valid, return -1 if the key
! 538: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 539: */
1.46 markus 540:
1.79.2.5! miod 541: static int
1.70 markus 542: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.79.2.5! miod 543: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 544: {
1.58 markus 545: Key *file_key;
1.72 markus 546: char *type = key_type(host_key);
1.46 markus 547: char *ip = NULL;
1.79.2.3 jason 548: char hostline[1000], *hostp, *fp;
1.38 markus 549: HostStatus host_status;
550: HostStatus ip_status;
1.49 markus 551: int local = 0, host_ip_differ = 0;
552: char ntop[NI_MAXHOST];
1.79.2.1 jason 553: int host_line, ip_line;
554: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 555:
556: /*
557: * Force accepting of the host key for loopback/localhost. The
558: * problem is that if the home directory is NFS-mounted to multiple
559: * machines, localhost will refer to a different machine in each of
560: * them, and the user will get bogus HOST_CHANGED warnings. This
561: * essentially disables host authentication for localhost; however,
562: * this is probably not a real problem.
563: */
1.70 markus 564: /** hostaddr == 0! */
1.49 markus 565: switch (hostaddr->sa_family) {
566: case AF_INET:
1.79.2.5! miod 567: local = (ntohl(((struct sockaddr_in *)hostaddr)->
! 568: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 569: break;
570: case AF_INET6:
1.79.2.5! miod 571: local = IN6_IS_ADDR_LOOPBACK(
! 572: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 573: break;
574: default:
575: local = 0;
576: break;
577: }
1.79.2.1 jason 578: if (local && options.host_key_alias == NULL) {
579: debug("Forcing accepting of host key for "
580: "loopback/localhost.");
1.79.2.5! miod 581: return 0;
1.49 markus 582: }
1.42 markus 583:
584: /*
1.79.2.1 jason 585: * We don't have the remote ip-address for connections
586: * using a proxy command
1.42 markus 587: */
1.79.2.1 jason 588: if (options.proxy_command == NULL) {
1.49 markus 589: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
590: NULL, 0, NI_NUMERICHOST) != 0)
591: fatal("check_host_key: getnameinfo failed");
592: ip = xstrdup(ntop);
1.79.2.1 jason 593: } else {
594: ip = xstrdup("<no hostip for proxy command>");
595: }
596: /*
597: * Turn off check_host_ip if the connection is to localhost, via proxy
598: * command or if we don't have a hostname to compare with
599: */
600: if (options.check_host_ip &&
601: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
602: options.check_host_ip = 0;
603:
604: /*
605: * Allow the user to record the key under a different name. This is
606: * useful for ssh tunneling over forwarded connections or if you run
607: * multiple sshd's on different ports on the same machine.
608: */
609: if (options.host_key_alias != NULL) {
610: host = options.host_key_alias;
611: debug("using hostkeyalias: %s", host);
1.49 markus 612: }
1.38 markus 613:
1.46 markus 614: /*
615: * Store the host key from the known host file in here so that we can
616: * compare it with the key for the IP address.
617: */
1.58 markus 618: file_key = key_new(host_key->type);
1.38 markus 619:
1.40 markus 620: /*
621: * Check if the host key is present in the user\'s list of known
622: * hosts or in the systemwide list.
623: */
1.79.2.1 jason 624: host_file = user_hostfile;
1.79.2.5! miod 625: host_status = check_host_in_hostfile(host_file, host, host_key,
! 626: file_key, &host_line);
1.79.2.1 jason 627: if (host_status == HOST_NEW) {
628: host_file = system_hostfile;
1.79.2.5! miod 629: host_status = check_host_in_hostfile(host_file, host, host_key,
! 630: file_key, &host_line);
1.79.2.1 jason 631: }
1.40 markus 632: /*
633: * Also perform check for the ip address, skip the check if we are
634: * localhost or the hostname was an ip address to begin with
635: */
1.79.2.1 jason 636: if (options.check_host_ip) {
1.58 markus 637: Key *ip_key = key_new(host_key->type);
1.38 markus 638:
1.79.2.1 jason 639: ip_file = user_hostfile;
1.79.2.5! miod 640: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
! 641: ip_key, &ip_line);
1.79.2.1 jason 642: if (ip_status == HOST_NEW) {
643: ip_file = system_hostfile;
1.79.2.5! miod 644: ip_status = check_host_in_hostfile(ip_file, ip,
! 645: host_key, ip_key, &ip_line);
1.79.2.1 jason 646: }
1.38 markus 647: if (host_status == HOST_CHANGED &&
1.58 markus 648: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 649: host_ip_differ = 1;
650:
1.58 markus 651: key_free(ip_key);
1.38 markus 652: } else
653: ip_status = host_status;
654:
1.58 markus 655: key_free(file_key);
1.38 markus 656:
657: switch (host_status) {
658: case HOST_OK:
659: /* The host is known and the key matches. */
1.72 markus 660: debug("Host '%.200s' is known and matches the %s host key.",
661: host, type);
1.79.2.1 jason 662: debug("Found key in %s:%d", host_file, host_line);
663: if (options.check_host_ip && ip_status == HOST_NEW) {
1.79.2.5! miod 664: if (readonly)
! 665: log("%s host key for IP address "
! 666: "'%.128s' not in list of known hosts.",
1.79.2.1 jason 667: type, ip);
1.79.2.5! miod 668: else if (!add_host_to_hostfile(user_hostfile, ip,
! 669: host_key))
! 670: log("Failed to add the %s host key for IP "
! 671: "address '%.128s' to the list of known "
! 672: "hosts (%.30s).", type, ip, user_hostfile);
! 673: else
! 674: log("Warning: Permanently added the %s host "
! 675: "key for IP address '%.128s' to the list "
! 676: "of known hosts.", type, ip);
1.38 markus 677: }
678: break;
679: case HOST_NEW:
1.79.2.5! miod 680: if (readonly)
! 681: goto fail;
1.38 markus 682: /* The host is new. */
683: if (options.strict_host_key_checking == 1) {
1.79.2.5! miod 684: /*
! 685: * User has requested strict host key checking. We
! 686: * will not add the host key automatically. The only
! 687: * alternative left is to abort.
! 688: */
! 689: error("No %s host key is known for %.200s and you "
! 690: "have requested strict checking.", type, host);
! 691: goto fail;
1.38 markus 692: } else if (options.strict_host_key_checking == 2) {
693: /* The default */
694: char prompt[1024];
1.79.2.3 jason 695: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 696: snprintf(prompt, sizeof(prompt),
1.79.2.5! miod 697: "The authenticity of host '%.200s (%s)' can't be "
! 698: "established.\n"
1.72 markus 699: "%s key fingerprint is %s.\n"
1.79.2.5! miod 700: "Are you sure you want to continue connecting "
! 701: "(yes/no)? ", host, ip, type, fp);
1.79.2.3 jason 702: xfree(fp);
1.79.2.5! miod 703: if (!read_yes_or_no(prompt, -1)) {
! 704: log("Aborted by user!");
! 705: goto fail;
! 706: }
1.38 markus 707: }
1.79.2.1 jason 708: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 709: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
710: hostp = hostline;
711: } else
712: hostp = host;
713:
1.79.2.5! miod 714: /*
! 715: * If not in strict mode, add the key automatically to the
! 716: * local known_hosts file.
! 717: */
1.70 markus 718: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.79.2.5! miod 719: log("Failed to add the host to the list of known "
! 720: "hosts (%.500s).", user_hostfile);
1.38 markus 721: else
1.79.2.5! miod 722: log("Warning: Permanently added '%.200s' (%s) to the "
! 723: "list of known hosts.", hostp, type);
1.38 markus 724: break;
725: case HOST_CHANGED:
726: if (options.check_host_ip && host_ip_differ) {
727: char *msg;
728: if (ip_status == HOST_NEW)
729: msg = "is unknown";
730: else if (ip_status == HOST_OK)
731: msg = "is unchanged";
732: else
733: msg = "has a different value";
734: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
735: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
736: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 737: error("The %s host key for %s has changed,", type, host);
1.38 markus 738: error("and the key for the according IP address %s", ip);
739: error("%s. This could either mean that", msg);
740: error("DNS SPOOFING is happening or the IP address for the host");
1.79.2.1 jason 741: error("and its host key have changed at the same time.");
742: if (ip_status != HOST_NEW)
743: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 744: }
745: /* The host key has changed. */
1.79.2.3 jason 746: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 747: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 748: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 749: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
750: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
751: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 752: error("It is also possible that the %s host key has just been changed.", type);
1.79.2.1 jason 753: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.79.2.3 jason 754: type, fp);
1.38 markus 755: error("Please contact your system administrator.");
756: error("Add correct host key in %.100s to get rid of this message.",
1.79.2.1 jason 757: user_hostfile);
758: error("Offending key in %s:%d", host_file, host_line);
1.79.2.3 jason 759: xfree(fp);
1.38 markus 760:
1.40 markus 761: /*
762: * If strict host key checking is in use, the user will have
763: * to edit the key manually and we can only abort.
764: */
1.79.2.5! miod 765: if (options.strict_host_key_checking) {
! 766: error("%s host key for %.200s has changed and you have "
! 767: "requested strict checking.", type, host);
! 768: goto fail;
! 769: }
1.38 markus 770:
1.40 markus 771: /*
772: * If strict host key checking has not been requested, allow
773: * the connection but without password authentication or
774: * agent forwarding.
775: */
1.38 markus 776: if (options.password_authentication) {
1.79.2.5! miod 777: error("Password authentication is disabled to avoid "
! 778: "man-in-the-middle attacks.");
1.38 markus 779: options.password_authentication = 0;
780: }
781: if (options.forward_agent) {
1.79.2.5! miod 782: error("Agent forwarding is disabled to avoid "
! 783: "man-in-the-middle attacks.");
1.38 markus 784: options.forward_agent = 0;
785: }
1.79.2.1 jason 786: if (options.forward_x11) {
1.79.2.5! miod 787: error("X11 forwarding is disabled to avoid "
! 788: "man-in-the-middle attacks.");
1.79.2.1 jason 789: options.forward_x11 = 0;
790: }
1.79.2.5! miod 791: if (options.num_local_forwards > 0 ||
! 792: options.num_remote_forwards > 0) {
! 793: error("Port forwarding is disabled to avoid "
! 794: "man-in-the-middle attacks.");
! 795: options.num_local_forwards =
! 796: options.num_remote_forwards = 0;
1.79.2.1 jason 797: }
1.40 markus 798: /*
799: * XXX Should permit the user to change to use the new id.
800: * This could be done by converting the host key to an
801: * identifying sentence, tell that the host identifies itself
802: * by that sentence, and ask the user if he/she whishes to
803: * accept the authentication.
804: */
1.38 markus 805: break;
806: }
1.79.2.1 jason 807:
808: if (options.check_host_ip && host_status != HOST_CHANGED &&
809: ip_status == HOST_CHANGED) {
810: log("Warning: the %s host key for '%.200s' "
811: "differs from the key for the IP address '%.128s'",
812: type, host, ip);
813: if (host_status == HOST_OK)
814: log("Matching host key in %s:%d", host_file, host_line);
815: log("Offending key for IP in %s:%d", ip_file, ip_line);
816: if (options.strict_host_key_checking == 1) {
1.79.2.5! miod 817: error("Exiting, you have requested strict checking.");
! 818: goto fail;
1.79.2.1 jason 819: } else if (options.strict_host_key_checking == 2) {
1.79.2.5! miod 820: if (!read_yes_or_no("Are you sure you want "
! 821: "to continue connecting (yes/no)? ", -1)) {
! 822: log("Aborted by user!");
! 823: goto fail;
! 824: }
1.79.2.1 jason 825: }
826: }
827:
828: xfree(ip);
1.79.2.5! miod 829: return 0;
! 830:
! 831: fail:
! 832: xfree(ip);
! 833: return -1;
! 834: }
! 835:
! 836: int
! 837: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
! 838: {
! 839: struct stat st;
! 840:
! 841: /* return ok if the key can be found in an old keyfile */
! 842: if (stat(options.system_hostfile2, &st) == 0 ||
! 843: stat(options.user_hostfile2, &st) == 0) {
! 844: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
! 845: options.user_hostfile2, options.system_hostfile2) == 0)
! 846: return 0;
! 847: }
! 848: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
! 849: options.user_hostfile, options.system_hostfile);
1.51 markus 850: }
1.70 markus 851:
1.51 markus 852: /*
853: * Starts a dialog with the server, and authenticates the current user on the
854: * server. This does not need any extra privileges. The basic connection
855: * to the server must already have been established before this is called.
856: * If login fails, this function prints an error and never returns.
857: * This function does not require super-user privileges.
858: */
859: void
1.79.2.4 jason 860: ssh_login(Key **keys, int nkeys, const char *orighost,
861: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 862: {
863: char *host, *cp;
1.70 markus 864: char *server_user, *local_user;
865:
866: local_user = xstrdup(pw->pw_name);
867: server_user = options.user ? options.user : local_user;
1.51 markus 868:
869: /* Convert the user-supplied hostname into all lowercase. */
870: host = xstrdup(orighost);
871: for (cp = host; *cp; cp++)
872: if (isupper(*cp))
873: *cp = tolower(*cp);
874:
875: /* Exchange protocol version identification strings with the server. */
876: ssh_exchange_identification();
877:
878: /* Put the connection into non-blocking mode. */
879: packet_set_nonblocking();
880:
881: /* key exchange */
882: /* authenticate user */
1.59 markus 883: if (compat20) {
884: ssh_kex2(host, hostaddr);
1.79.2.4 jason 885: ssh_userauth2(local_user, server_user, host, keys, nkeys);
1.59 markus 886: } else {
887: ssh_kex(host, hostaddr);
1.79.2.4 jason 888: ssh_userauth1(local_user, server_user, host, keys, nkeys);
1.59 markus 889: }
1.79.2.1 jason 890: }
891:
892: void
893: ssh_put_password(char *password)
894: {
895: int size;
896: char *padded;
897:
1.79.2.3 jason 898: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.79.2.5! miod 899: packet_put_cstring(password);
1.79.2.3 jason 900: return;
901: }
1.79.2.1 jason 902: size = roundup(strlen(password) + 1, 32);
903: padded = xmalloc(size);
904: memset(padded, 0, size);
905: strlcpy(padded, password, size);
906: packet_put_string(padded, size);
907: memset(padded, 0, size);
908: xfree(padded);
1.1 deraadt 909: }
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