Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.139
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"
1.139 ! markus 16: RCSID("$OpenBSD: sshconnect.c,v 1.138 2003/04/08 20:21:29 itojun 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"
1.119 markus 34: #include "readpass.h"
1.51 markus 35:
1.70 markus 36: char *client_version_string = NULL;
37: char *server_version_string = NULL;
1.59 markus 38:
1.124 markus 39: /* import */
1.43 markus 40: extern Options options;
1.50 markus 41: extern char *__progname;
1.124 markus 42: extern uid_t original_real_uid;
43: extern uid_t original_effective_uid;
1.135 djm 44: extern pid_t proxy_command_pid;
1.91 markus 45:
1.132 markus 46: static int show_other_keys(const char *, Key *);
47:
1.39 deraadt 48: /*
49: * Connect to the given ssh server using a proxy command.
50: */
1.109 itojun 51: static int
1.124 markus 52: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 53: {
1.38 markus 54: Buffer command;
55: const char *cp;
56: char *command_string;
57: int pin[2], pout[2];
1.69 deraadt 58: pid_t pid;
1.49 markus 59: char strport[NI_MAXSERV];
1.38 markus 60:
61: /* Convert the port number into a string. */
1.49 markus 62: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 63:
1.135 djm 64: /*
65: * Build the final command string in the buffer by making the
66: * appropriate substitutions to the given proxy command.
67: *
68: * Use "exec" to avoid "sh -c" processes on some platforms
69: * (e.g. Solaris)
70: */
1.38 markus 71: buffer_init(&command);
1.135 djm 72: buffer_append(&command, "exec ", 5);
73:
1.38 markus 74: for (cp = proxy_command; *cp; cp++) {
75: if (cp[0] == '%' && cp[1] == '%') {
76: buffer_append(&command, "%", 1);
77: cp++;
78: continue;
79: }
80: if (cp[0] == '%' && cp[1] == 'h') {
81: buffer_append(&command, host, strlen(host));
82: cp++;
83: continue;
84: }
85: if (cp[0] == '%' && cp[1] == 'p') {
1.49 markus 86: buffer_append(&command, strport, strlen(strport));
1.38 markus 87: cp++;
88: continue;
89: }
90: buffer_append(&command, cp, 1);
91: }
92: buffer_append(&command, "\0", 1);
93:
94: /* Get the final command string. */
95: command_string = buffer_ptr(&command);
96:
97: /* Create pipes for communicating with the proxy. */
98: if (pipe(pin) < 0 || pipe(pout) < 0)
99: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 100: strerror(errno));
1.38 markus 101:
102: debug("Executing proxy command: %.500s", command_string);
103:
104: /* Fork and execute the proxy command. */
105: if ((pid = fork()) == 0) {
106: char *argv[10];
107:
108: /* Child. Permanently give up superuser privileges. */
1.124 markus 109: seteuid(original_real_uid);
110: setuid(original_real_uid);
1.38 markus 111:
112: /* Redirect stdin and stdout. */
113: close(pin[1]);
114: if (pin[0] != 0) {
115: if (dup2(pin[0], 0) < 0)
116: perror("dup2 stdin");
117: close(pin[0]);
118: }
119: close(pout[0]);
120: if (dup2(pout[1], 1) < 0)
121: perror("dup2 stdout");
122: /* Cannot be 1 because pin allocated two descriptors. */
123: close(pout[1]);
124:
125: /* Stderr is left as it is so that error messages get
126: printed on the user's terminal. */
1.89 markus 127: argv[0] = _PATH_BSHELL;
1.38 markus 128: argv[1] = "-c";
129: argv[2] = command_string;
130: argv[3] = NULL;
131:
132: /* Execute the proxy command. Note that we gave up any
133: extra privileges above. */
1.89 markus 134: execv(argv[0], argv);
135: perror(argv[0]);
1.38 markus 136: exit(1);
137: }
138: /* Parent. */
139: if (pid < 0)
140: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 141: else
142: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 143:
144: /* Close child side of the descriptors. */
145: close(pin[0]);
146: close(pout[1]);
147:
148: /* Free the command name. */
149: buffer_free(&command);
150:
151: /* Set the connection file descriptors. */
152: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 153:
1.110 markus 154: /* Indicate OK return */
155: return 0;
1.1 deraadt 156: }
157:
1.39 deraadt 158: /*
159: * Creates a (possibly privileged) socket for use as the ssh connection.
160: */
1.109 itojun 161: static int
1.139 ! markus 162: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 163: {
1.105 markus 164: int sock, gaierr;
165: struct addrinfo hints, *res;
1.1 deraadt 166:
1.40 markus 167: /*
168: * If we are running as root and want to connect to a privileged
169: * port, bind our own socket to a privileged port.
170: */
1.38 markus 171: if (privileged) {
172: int p = IPPORT_RESERVED - 1;
1.124 markus 173: PRIV_START;
1.139 ! markus 174: sock = rresvport_af(&p, ai->ai_family);
1.124 markus 175: PRIV_END;
1.38 markus 176: if (sock < 0)
1.139 ! markus 177: error("rresvport: af=%d %.100s", ai->ai_family,
! 178: strerror(errno));
1.55 markus 179: else
180: debug("Allocated local port %d.", p);
1.105 markus 181: return sock;
182: }
1.139 ! markus 183: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.105 markus 184: if (sock < 0)
185: error("socket: %.100s", strerror(errno));
186:
187: /* Bind the socket to an alternative local IP address */
188: if (options.bind_address == NULL)
189: return sock;
190:
191: memset(&hints, 0, sizeof(hints));
1.139 ! markus 192: hints.ai_family = ai->ai_family;
! 193: hints.ai_socktype = ai->ai_socktype;
! 194: hints.ai_protocol = ai->ai_protocol;
1.105 markus 195: hints.ai_flags = AI_PASSIVE;
196: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
197: if (gaierr) {
198: error("getaddrinfo: %s: %s", options.bind_address,
199: gai_strerror(gaierr));
200: close(sock);
201: return -1;
202: }
203: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
204: error("bind: %s: %s", options.bind_address, strerror(errno));
205: close(sock);
206: freeaddrinfo(res);
207: return -1;
1.38 markus 208: }
1.105 markus 209: freeaddrinfo(res);
1.38 markus 210: return sock;
1.1 deraadt 211: }
212:
1.39 deraadt 213: /*
1.49 markus 214: * Opens a TCP/IP connection to the remote server on the given host.
215: * The address of the remote host will be returned in hostaddr.
1.124 markus 216: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 217: * a privileged port will be allocated to make the connection.
1.124 markus 218: * This requires super-user privileges if needpriv is true.
1.39 deraadt 219: * Connection_attempts specifies the maximum number of tries (one per
220: * second). If proxy_command is non-NULL, it specifies the command (with %h
221: * and %p substituted for host and port, respectively) to use to contact
222: * the daemon.
1.110 markus 223: * Return values:
224: * 0 for OK
225: * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
226: * ECONNABORTED if we failed without a "Connection refused"
227: * Suitable error messages for the connection failure will already have been
228: * printed.
1.39 deraadt 229: */
1.38 markus 230: int
1.49 markus 231: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 232: u_short port, int family, int connection_attempts,
1.124 markus 233: int needpriv, const char *proxy_command)
1.1 deraadt 234: {
1.90 markus 235: int gaierr;
236: int on = 1;
1.49 markus 237: int sock = -1, attempt;
1.90 markus 238: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 239: struct addrinfo hints, *ai, *aitop;
1.90 markus 240: struct servent *sp;
1.110 markus 241: /*
242: * Did we get only other errors than "Connection refused" (which
243: * should block fallback to rsh and similar), or did we get at least
244: * one "Connection refused"?
245: */
246: int full_failure = 1;
1.38 markus 247:
1.136 markus 248: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 249:
250: /* Get default port if port has not been set. */
251: if (port == 0) {
252: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
253: if (sp)
254: port = ntohs(sp->s_port);
255: else
256: port = SSH_DEFAULT_PORT;
257: }
258: /* If a proxy command is given, connect using it. */
259: if (proxy_command != NULL)
1.124 markus 260: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 261:
262: /* No proxy command. */
263:
1.49 markus 264: memset(&hints, 0, sizeof(hints));
1.115 markus 265: hints.ai_family = family;
1.49 markus 266: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 267: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 268: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 269: fatal("%s: %.100s: %s", __progname, host,
270: gai_strerror(gaierr));
1.38 markus 271:
1.46 markus 272: /*
273: * Try to connect several times. On some machines, the first time
274: * will sometimes fail. In general socket code appears to behave
275: * quite magically on many machines.
1.110 markus 276: */
277: for (attempt = 0; ;) {
1.38 markus 278: if (attempt > 0)
279: debug("Trying again...");
280:
1.49 markus 281: /* Loop through addresses for this host, and try each one in
1.68 markus 282: sequence until the connection succeeds. */
1.49 markus 283: for (ai = aitop; ai; ai = ai->ai_next) {
284: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
285: continue;
286: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
287: ntop, sizeof(ntop), strport, sizeof(strport),
288: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
289: error("ssh_connect: getnameinfo failed");
290: continue;
291: }
292: debug("Connecting to %.200s [%.100s] port %s.",
293: host, ntop, strport);
294:
295: /* Create a socket for connecting. */
1.139 ! markus 296: sock = ssh_create_socket(needpriv, ai);
1.49 markus 297: if (sock < 0)
1.110 markus 298: /* Any error is already output */
1.49 markus 299: continue;
300:
301: if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
302: /* Successful connection. */
1.102 markus 303: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 304: break;
1.49 markus 305: } else {
1.110 markus 306: if (errno == ECONNREFUSED)
307: full_failure = 0;
1.131 itojun 308: debug("connect to address %s port %s: %s",
309: ntop, strport, strerror(errno));
1.40 markus 310: /*
311: * Close the failed socket; there appear to
312: * be some problems when reusing a socket for
313: * which connect() has already returned an
314: * error.
315: */
1.38 markus 316: close(sock);
317: }
318: }
1.49 markus 319: if (ai)
320: break; /* Successful connection. */
1.1 deraadt 321:
1.110 markus 322: attempt++;
323: if (attempt >= connection_attempts)
324: break;
1.38 markus 325: /* Sleep a moment before retrying. */
326: sleep(1);
327: }
1.49 markus 328:
329: freeaddrinfo(aitop);
330:
1.38 markus 331: /* Return failure if we didn't get a successful connection. */
1.130 itojun 332: if (attempt >= connection_attempts) {
1.138 itojun 333: logit("ssh: connect to host %s port %s: %s",
1.130 itojun 334: host, strport, strerror(errno));
1.110 markus 335: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.130 itojun 336: }
1.38 markus 337:
338: debug("Connection established.");
1.90 markus 339:
340: /* Set keepalives if requested. */
341: if (options.keepalives &&
342: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
343: sizeof(on)) < 0)
344: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 345:
346: /* Set the connection. */
347: packet_set_connection(sock, sock);
1.1 deraadt 348:
1.110 markus 349: return 0;
1.59 markus 350: }
351:
1.43 markus 352: /*
1.39 deraadt 353: * Waits for the server identification string, and sends our own
354: * identification string.
355: */
1.109 itojun 356: static void
1.95 itojun 357: ssh_exchange_identification(void)
1.1 deraadt 358: {
1.38 markus 359: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 360: int remote_major, remote_minor, i, mismatch;
1.38 markus 361: int connection_in = packet_get_connection_in();
362: int connection_out = packet_get_connection_out();
1.93 stevesk 363: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 364:
365: /* Read other side\'s version identification. */
1.75 markus 366: for (;;) {
367: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 368: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 369: if (len < 0)
370: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
371: if (len != 1)
372: fatal("ssh_exchange_identification: Connection closed by remote host");
373: if (buf[i] == '\r') {
374: buf[i] = '\n';
375: buf[i + 1] = 0;
376: continue; /**XXX wait for \n */
377: }
378: if (buf[i] == '\n') {
379: buf[i + 1] = 0;
380: break;
381: }
1.38 markus 382: }
1.75 markus 383: buf[sizeof(buf) - 1] = 0;
1.76 markus 384: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 385: break;
1.75 markus 386: debug("ssh_exchange_identification: %s", buf);
1.38 markus 387: }
1.59 markus 388: server_version_string = xstrdup(buf);
1.38 markus 389:
1.40 markus 390: /*
391: * Check that the versions match. In future this might accept
392: * several versions and set appropriate flags to handle them.
393: */
1.59 markus 394: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
395: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 396: fatal("Bad remote protocol version identification: '%.100s'", buf);
397: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 398: remote_major, remote_minor, remote_version);
1.38 markus 399:
1.59 markus 400: compat_datafellows(remote_version);
1.64 markus 401: mismatch = 0;
1.59 markus 402:
1.116 deraadt 403: switch (remote_major) {
1.64 markus 404: case 1:
405: if (remote_minor == 99 &&
406: (options.protocol & SSH_PROTO_2) &&
407: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
408: enable_compat20();
409: break;
410: }
411: if (!(options.protocol & SSH_PROTO_1)) {
412: mismatch = 1;
413: break;
414: }
415: if (remote_minor < 3) {
416: fatal("Remote machine has too old SSH software version.");
1.81 markus 417: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 418: /* We speak 1.3, too. */
419: enable_compat13();
1.81 markus 420: minor1 = 3;
1.64 markus 421: if (options.forward_agent) {
1.138 itojun 422: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 423: options.forward_agent = 0;
424: }
425: }
426: break;
427: case 2:
428: if (options.protocol & SSH_PROTO_2) {
429: enable_compat20();
430: break;
1.38 markus 431: }
1.64 markus 432: /* FALLTHROUGH */
1.68 markus 433: default:
1.64 markus 434: mismatch = 1;
435: break;
1.38 markus 436: }
1.64 markus 437: if (mismatch)
1.38 markus 438: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 439: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
440: remote_major);
1.38 markus 441: /* Send our own protocol version identification. */
442: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 443: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 444: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 445: SSH_VERSION);
1.45 deraadt 446: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 447: fatal("write: %.100s", strerror(errno));
1.59 markus 448: client_version_string = xstrdup(buf);
449: chop(client_version_string);
450: chop(server_version_string);
451: debug("Local version string %.100s", client_version_string);
1.1 deraadt 452: }
453:
1.96 markus 454: /* defaults to 'no' */
1.109 itojun 455: static int
1.112 markus 456: confirm(const char *prompt)
1.1 deraadt 457: {
1.119 markus 458: const char *msg, *again = "Please type 'yes' or 'no': ";
459: char *p;
460: int ret = -1;
1.96 markus 461:
462: if (options.batch_mode)
463: return 0;
1.119 markus 464: for (msg = prompt;;msg = again) {
465: p = read_passphrase(msg, RP_ECHO);
466: if (p == NULL ||
467: (p[0] == '\0') || (p[0] == '\n') ||
468: strncasecmp(p, "no", 2) == 0)
469: ret = 0;
1.127 markus 470: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 471: ret = 1;
472: if (p)
473: xfree(p);
474: if (ret != -1)
475: return ret;
1.1 deraadt 476: }
477: }
478:
1.39 deraadt 479: /*
1.108 markus 480: * check whether the supplied host key is valid, return -1 if the key
481: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 482: */
1.109 itojun 483: static int
1.70 markus 484: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 485: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 486: {
1.58 markus 487: Key *file_key;
1.72 markus 488: char *type = key_type(host_key);
1.46 markus 489: char *ip = NULL;
1.100 markus 490: char hostline[1000], *hostp, *fp;
1.38 markus 491: HostStatus host_status;
492: HostStatus ip_status;
1.49 markus 493: int local = 0, host_ip_differ = 0;
494: char ntop[NI_MAXHOST];
1.119 markus 495: char msg[1024];
1.132 markus 496: int len, host_line, ip_line, has_keys;
1.85 markus 497: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 498:
499: /*
500: * Force accepting of the host key for loopback/localhost. The
501: * problem is that if the home directory is NFS-mounted to multiple
502: * machines, localhost will refer to a different machine in each of
503: * them, and the user will get bogus HOST_CHANGED warnings. This
504: * essentially disables host authentication for localhost; however,
505: * this is probably not a real problem.
506: */
1.70 markus 507: /** hostaddr == 0! */
1.49 markus 508: switch (hostaddr->sa_family) {
509: case AF_INET:
1.108 markus 510: local = (ntohl(((struct sockaddr_in *)hostaddr)->
511: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 512: break;
513: case AF_INET6:
1.108 markus 514: local = IN6_IS_ADDR_LOOPBACK(
515: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 516: break;
517: default:
518: local = 0;
519: break;
520: }
1.111 markus 521: if (options.no_host_authentication_for_localhost == 1 && local &&
522: options.host_key_alias == NULL) {
1.88 markus 523: debug("Forcing accepting of host key for "
524: "loopback/localhost.");
1.108 markus 525: return 0;
1.49 markus 526: }
1.42 markus 527:
528: /*
1.88 markus 529: * We don't have the remote ip-address for connections
530: * using a proxy command
1.42 markus 531: */
1.84 markus 532: if (options.proxy_command == NULL) {
533: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 534: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 535: fatal("check_host_key: getnameinfo failed");
536: ip = xstrdup(ntop);
537: } else {
538: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 539: }
1.88 markus 540: /*
541: * Turn off check_host_ip if the connection is to localhost, via proxy
542: * command or if we don't have a hostname to compare with
543: */
544: if (options.check_host_ip &&
545: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
546: options.check_host_ip = 0;
1.86 markus 547:
548: /*
549: * Allow the user to record the key under a different name. This is
550: * useful for ssh tunneling over forwarded connections or if you run
551: * multiple sshd's on different ports on the same machine.
552: */
553: if (options.host_key_alias != NULL) {
554: host = options.host_key_alias;
555: debug("using hostkeyalias: %s", host);
1.84 markus 556: }
1.38 markus 557:
1.46 markus 558: /*
559: * Store the host key from the known host file in here so that we can
560: * compare it with the key for the IP address.
561: */
1.58 markus 562: file_key = key_new(host_key->type);
1.38 markus 563:
1.40 markus 564: /*
565: * Check if the host key is present in the user\'s list of known
566: * hosts or in the systemwide list.
567: */
1.85 markus 568: host_file = user_hostfile;
1.108 markus 569: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 570: file_key, &host_line);
1.85 markus 571: if (host_status == HOST_NEW) {
572: host_file = system_hostfile;
1.108 markus 573: host_status = check_host_in_hostfile(host_file, host, host_key,
574: file_key, &host_line);
1.85 markus 575: }
1.40 markus 576: /*
577: * Also perform check for the ip address, skip the check if we are
578: * localhost or the hostname was an ip address to begin with
579: */
1.88 markus 580: if (options.check_host_ip) {
1.58 markus 581: Key *ip_key = key_new(host_key->type);
1.38 markus 582:
1.85 markus 583: ip_file = user_hostfile;
1.108 markus 584: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
585: ip_key, &ip_line);
1.85 markus 586: if (ip_status == HOST_NEW) {
587: ip_file = system_hostfile;
1.108 markus 588: ip_status = check_host_in_hostfile(ip_file, ip,
589: host_key, ip_key, &ip_line);
1.85 markus 590: }
1.38 markus 591: if (host_status == HOST_CHANGED &&
1.58 markus 592: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 593: host_ip_differ = 1;
594:
1.58 markus 595: key_free(ip_key);
1.38 markus 596: } else
597: ip_status = host_status;
598:
1.58 markus 599: key_free(file_key);
1.38 markus 600:
601: switch (host_status) {
602: case HOST_OK:
603: /* The host is known and the key matches. */
1.72 markus 604: debug("Host '%.200s' is known and matches the %s host key.",
605: host, type);
1.85 markus 606: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 607: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 608: if (readonly)
1.138 itojun 609: logit("%s host key for IP address "
1.108 markus 610: "'%.128s' not in list of known hosts.",
611: type, ip);
612: else if (!add_host_to_hostfile(user_hostfile, ip,
1.118 deraadt 613: host_key))
1.138 itojun 614: logit("Failed to add the %s host key for IP "
1.108 markus 615: "address '%.128s' to the list of known "
616: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 617: else
1.138 itojun 618: logit("Warning: Permanently added the %s host "
1.108 markus 619: "key for IP address '%.128s' to the list "
620: "of known hosts.", type, ip);
1.38 markus 621: }
622: break;
623: case HOST_NEW:
1.108 markus 624: if (readonly)
625: goto fail;
1.38 markus 626: /* The host is new. */
627: if (options.strict_host_key_checking == 1) {
1.108 markus 628: /*
629: * User has requested strict host key checking. We
630: * will not add the host key automatically. The only
631: * alternative left is to abort.
632: */
633: error("No %s host key is known for %.200s and you "
634: "have requested strict checking.", type, host);
635: goto fail;
1.38 markus 636: } else if (options.strict_host_key_checking == 2) {
1.132 markus 637: has_keys = show_other_keys(host, host_key);
1.38 markus 638: /* The default */
1.100 markus 639: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.119 markus 640: snprintf(msg, sizeof(msg),
1.108 markus 641: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 642: "established%s\n"
1.72 markus 643: "%s key fingerprint is %s.\n"
1.108 markus 644: "Are you sure you want to continue connecting "
1.132 markus 645: "(yes/no)? ",
1.137 deraadt 646: host, ip,
647: has_keys ? ",\nbut keys of different type are already "
648: "known for this host." : ".",
649: type, fp);
1.100 markus 650: xfree(fp);
1.119 markus 651: if (!confirm(msg))
1.108 markus 652: goto fail;
1.38 markus 653: }
1.88 markus 654: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 655: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
656: hostp = hostline;
657: } else
658: hostp = host;
659:
1.108 markus 660: /*
661: * If not in strict mode, add the key automatically to the
662: * local known_hosts file.
663: */
1.70 markus 664: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.138 itojun 665: logit("Failed to add the host to the list of known "
1.108 markus 666: "hosts (%.500s).", user_hostfile);
1.38 markus 667: else
1.138 itojun 668: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 669: "list of known hosts.", hostp, type);
1.38 markus 670: break;
671: case HOST_CHANGED:
672: if (options.check_host_ip && host_ip_differ) {
673: char *msg;
674: if (ip_status == HOST_NEW)
675: msg = "is unknown";
676: else if (ip_status == HOST_OK)
677: msg = "is unchanged";
678: else
679: msg = "has a different value";
680: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
681: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
682: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 683: error("The %s host key for %s has changed,", type, host);
1.38 markus 684: error("and the key for the according IP address %s", ip);
685: error("%s. This could either mean that", msg);
686: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 687: error("and its host key have changed at the same time.");
1.88 markus 688: if (ip_status != HOST_NEW)
1.85 markus 689: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 690: }
691: /* The host key has changed. */
1.100 markus 692: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 693: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 694: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 695: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
696: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
697: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 698: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 699: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.100 markus 700: type, fp);
1.38 markus 701: error("Please contact your system administrator.");
702: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 703: user_hostfile);
1.85 markus 704: error("Offending key in %s:%d", host_file, host_line);
1.100 markus 705: xfree(fp);
1.38 markus 706:
1.40 markus 707: /*
708: * If strict host key checking is in use, the user will have
709: * to edit the key manually and we can only abort.
710: */
1.108 markus 711: if (options.strict_host_key_checking) {
712: error("%s host key for %.200s has changed and you have "
713: "requested strict checking.", type, host);
714: goto fail;
715: }
1.38 markus 716:
1.40 markus 717: /*
718: * If strict host key checking has not been requested, allow
719: * the connection but without password authentication or
720: * agent forwarding.
721: */
1.38 markus 722: if (options.password_authentication) {
1.108 markus 723: error("Password authentication is disabled to avoid "
724: "man-in-the-middle attacks.");
1.38 markus 725: options.password_authentication = 0;
726: }
727: if (options.forward_agent) {
1.108 markus 728: error("Agent forwarding is disabled to avoid "
729: "man-in-the-middle attacks.");
1.38 markus 730: options.forward_agent = 0;
1.83 markus 731: }
732: if (options.forward_x11) {
1.108 markus 733: error("X11 forwarding is disabled to avoid "
734: "man-in-the-middle attacks.");
1.83 markus 735: options.forward_x11 = 0;
736: }
1.108 markus 737: if (options.num_local_forwards > 0 ||
738: options.num_remote_forwards > 0) {
739: error("Port forwarding is disabled to avoid "
740: "man-in-the-middle attacks.");
741: options.num_local_forwards =
1.118 deraadt 742: options.num_remote_forwards = 0;
1.38 markus 743: }
1.40 markus 744: /*
745: * XXX Should permit the user to change to use the new id.
746: * This could be done by converting the host key to an
747: * identifying sentence, tell that the host identifies itself
748: * by that sentence, and ask the user if he/she whishes to
749: * accept the authentication.
750: */
1.38 markus 751: break;
1.132 markus 752: case HOST_FOUND:
753: fatal("internal error");
754: break;
1.88 markus 755: }
756:
757: if (options.check_host_ip && host_status != HOST_CHANGED &&
758: ip_status == HOST_CHANGED) {
1.119 markus 759: snprintf(msg, sizeof(msg),
760: "Warning: the %s host key for '%.200s' "
761: "differs from the key for the IP address '%.128s'"
762: "\nOffending key for IP in %s:%d",
763: type, host, ip, ip_file, ip_line);
764: if (host_status == HOST_OK) {
765: len = strlen(msg);
766: snprintf(msg + len, sizeof(msg) - len,
767: "\nMatching host key in %s:%d",
1.125 deraadt 768: host_file, host_line);
1.119 markus 769: }
1.88 markus 770: if (options.strict_host_key_checking == 1) {
1.138 itojun 771: logit(msg);
1.108 markus 772: error("Exiting, you have requested strict checking.");
773: goto fail;
1.88 markus 774: } else if (options.strict_host_key_checking == 2) {
1.119 markus 775: strlcat(msg, "\nAre you sure you want "
776: "to continue connecting (yes/no)? ", sizeof(msg));
777: if (!confirm(msg))
1.108 markus 778: goto fail;
1.119 markus 779: } else {
1.138 itojun 780: logit(msg);
1.88 markus 781: }
1.38 markus 782: }
1.82 provos 783:
784: xfree(ip);
1.108 markus 785: return 0;
786:
787: fail:
788: xfree(ip);
789: return -1;
790: }
791:
792: int
793: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
794: {
795: struct stat st;
796:
797: /* return ok if the key can be found in an old keyfile */
798: if (stat(options.system_hostfile2, &st) == 0 ||
799: stat(options.user_hostfile2, &st) == 0) {
800: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
801: options.user_hostfile2, options.system_hostfile2) == 0)
802: return 0;
803: }
804: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
805: options.user_hostfile, options.system_hostfile);
1.51 markus 806: }
1.70 markus 807:
1.51 markus 808: /*
809: * Starts a dialog with the server, and authenticates the current user on the
810: * server. This does not need any extra privileges. The basic connection
811: * to the server must already have been established before this is called.
812: * If login fails, this function prints an error and never returns.
813: * This function does not require super-user privileges.
814: */
815: void
1.120 markus 816: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 817: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 818: {
819: char *host, *cp;
1.70 markus 820: char *server_user, *local_user;
821:
822: local_user = xstrdup(pw->pw_name);
823: server_user = options.user ? options.user : local_user;
1.51 markus 824:
825: /* Convert the user-supplied hostname into all lowercase. */
826: host = xstrdup(orighost);
827: for (cp = host; *cp; cp++)
828: if (isupper(*cp))
829: *cp = tolower(*cp);
830:
831: /* Exchange protocol version identification strings with the server. */
832: ssh_exchange_identification();
833:
834: /* Put the connection into non-blocking mode. */
835: packet_set_nonblocking();
836:
837: /* key exchange */
838: /* authenticate user */
1.59 markus 839: if (compat20) {
840: ssh_kex2(host, hostaddr);
1.120 markus 841: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 842: } else {
843: ssh_kex(host, hostaddr);
1.120 markus 844: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 845: }
1.97 markus 846: }
847:
848: void
849: ssh_put_password(char *password)
850: {
851: int size;
852: char *padded;
853:
1.99 deraadt 854: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 855: packet_put_cstring(password);
1.99 deraadt 856: return;
857: }
1.97 markus 858: size = roundup(strlen(password) + 1, 32);
859: padded = xmalloc(size);
860: memset(padded, 0, size);
861: strlcpy(padded, password, size);
862: packet_put_string(padded, size);
863: memset(padded, 0, size);
864: xfree(padded);
1.132 markus 865: }
866:
867: static int
868: show_key_from_file(const char *file, const char *host, int keytype)
869: {
870: Key *found;
871: char *fp;
872: int line, ret;
873:
874: found = key_new(keytype);
875: if ((ret = lookup_key_in_hostfile_by_type(file, host,
876: keytype, found, &line))) {
877: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 878: logit("WARNING: %s key found for host %s\n"
1.133 markus 879: "in %s:%d\n"
1.132 markus 880: "%s key fingerprint %s.",
881: key_type(found), host, file, line,
882: key_type(found), fp);
883: xfree(fp);
884: }
885: key_free(found);
886: return (ret);
887: }
888:
889: /* print all known host keys for a given host, but skip keys of given type */
890: static int
891: show_other_keys(const char *host, Key *key)
892: {
893: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
894: int i, found = 0;
895:
896: for (i = 0; type[i] != -1; i++) {
897: if (type[i] == key->type)
898: continue;
899: if (type[i] != KEY_RSA1 &&
900: show_key_from_file(options.user_hostfile2, host, type[i])) {
901: found = 1;
902: continue;
903: }
904: if (type[i] != KEY_RSA1 &&
905: show_key_from_file(options.system_hostfile2, host, type[i])) {
906: found = 1;
907: continue;
908: }
909: if (show_key_from_file(options.user_hostfile, host, type[i])) {
910: found = 1;
911: continue;
912: }
913: if (show_key_from_file(options.system_hostfile, host, type[i])) {
914: found = 1;
915: continue;
916: }
917: debug2("no key of type %d for host %s", type[i], host);
918: }
919: return (found);
1.1 deraadt 920: }
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