Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.117
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"
1.117 ! stevesk 16: RCSID("$OpenBSD: sshconnect.c,v 1.116 2001/12/05 10:06:13 deraadt 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:
1.70 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;
1.91 markus 40:
1.110 markus 41: static const char *
42: sockaddr_ntop(struct sockaddr *sa)
43: {
44: void *addr;
45: static char addrbuf[INET6_ADDRSTRLEN];
46:
47: switch (sa->sa_family) {
1.116 deraadt 48: case AF_INET:
49: addr = &((struct sockaddr_in *)sa)->sin_addr;
50: break;
51: case AF_INET6:
52: addr = &((struct sockaddr_in6 *)sa)->sin6_addr;
53: break;
54: default:
55: /* This case should be protected against elsewhere */
56: abort(); /* XXX abort is bad -- do something else */
1.110 markus 57: }
58: inet_ntop(sa->sa_family, addr, addrbuf, sizeof(addrbuf));
59: return addrbuf;
60: }
61:
1.39 deraadt 62: /*
63: * Connect to the given ssh server using a proxy command.
64: */
1.109 itojun 65: static int
1.103 markus 66: ssh_proxy_connect(const char *host, u_short port, struct passwd *pw,
1.3 provos 67: const char *proxy_command)
1.1 deraadt 68: {
1.38 markus 69: Buffer command;
70: const char *cp;
71: char *command_string;
72: int pin[2], pout[2];
1.69 deraadt 73: pid_t pid;
1.49 markus 74: char strport[NI_MAXSERV];
1.38 markus 75:
76: /* Convert the port number into a string. */
1.49 markus 77: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 78:
79: /* Build the final command string in the buffer by making the
80: appropriate substitutions to the given proxy command. */
81: buffer_init(&command);
82: for (cp = proxy_command; *cp; cp++) {
83: if (cp[0] == '%' && cp[1] == '%') {
84: buffer_append(&command, "%", 1);
85: cp++;
86: continue;
87: }
88: if (cp[0] == '%' && cp[1] == 'h') {
89: buffer_append(&command, host, strlen(host));
90: cp++;
91: continue;
92: }
93: if (cp[0] == '%' && cp[1] == 'p') {
1.49 markus 94: buffer_append(&command, strport, strlen(strport));
1.38 markus 95: cp++;
96: continue;
97: }
98: buffer_append(&command, cp, 1);
99: }
100: buffer_append(&command, "\0", 1);
101:
102: /* Get the final command string. */
103: command_string = buffer_ptr(&command);
104:
105: /* Create pipes for communicating with the proxy. */
106: if (pipe(pin) < 0 || pipe(pout) < 0)
107: fatal("Could not create pipes to communicate with the proxy: %.100s",
108: strerror(errno));
109:
110: debug("Executing proxy command: %.500s", command_string);
111:
112: /* Fork and execute the proxy command. */
113: if ((pid = fork()) == 0) {
114: char *argv[10];
115:
116: /* Child. Permanently give up superuser privileges. */
1.103 markus 117: permanently_set_uid(pw);
1.38 markus 118:
119: /* Redirect stdin and stdout. */
120: close(pin[1]);
121: if (pin[0] != 0) {
122: if (dup2(pin[0], 0) < 0)
123: perror("dup2 stdin");
124: close(pin[0]);
125: }
126: close(pout[0]);
127: if (dup2(pout[1], 1) < 0)
128: perror("dup2 stdout");
129: /* Cannot be 1 because pin allocated two descriptors. */
130: close(pout[1]);
131:
132: /* Stderr is left as it is so that error messages get
133: printed on the user's terminal. */
1.89 markus 134: argv[0] = _PATH_BSHELL;
1.38 markus 135: argv[1] = "-c";
136: argv[2] = command_string;
137: argv[3] = NULL;
138:
139: /* Execute the proxy command. Note that we gave up any
140: extra privileges above. */
1.89 markus 141: execv(argv[0], argv);
142: perror(argv[0]);
1.38 markus 143: exit(1);
144: }
145: /* Parent. */
146: if (pid < 0)
147: fatal("fork failed: %.100s", strerror(errno));
148:
149: /* Close child side of the descriptors. */
150: close(pin[0]);
151: close(pout[1]);
152:
153: /* Free the command name. */
154: buffer_free(&command);
155:
156: /* Set the connection file descriptors. */
157: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 158:
1.110 markus 159: /* Indicate OK return */
160: return 0;
1.1 deraadt 161: }
162:
1.39 deraadt 163: /*
164: * Creates a (possibly privileged) socket for use as the ssh connection.
165: */
1.109 itojun 166: static int
1.103 markus 167: ssh_create_socket(struct passwd *pw, int privileged, int family)
1.1 deraadt 168: {
1.105 markus 169: int sock, gaierr;
170: struct addrinfo hints, *res;
1.1 deraadt 171:
1.40 markus 172: /*
173: * If we are running as root and want to connect to a privileged
174: * port, bind our own socket to a privileged port.
175: */
1.38 markus 176: if (privileged) {
177: int p = IPPORT_RESERVED - 1;
1.49 markus 178: sock = rresvport_af(&p, family);
1.38 markus 179: if (sock < 0)
1.55 markus 180: error("rresvport: af=%d %.100s", family, strerror(errno));
181: else
182: debug("Allocated local port %d.", p);
1.105 markus 183: return sock;
184: }
185: /*
186: * Just create an ordinary socket on arbitrary port. We use
187: * the user's uid to create the socket.
188: */
189: temporarily_use_uid(pw);
190: sock = socket(family, SOCK_STREAM, 0);
191: if (sock < 0)
192: error("socket: %.100s", strerror(errno));
193: restore_uid();
194:
195: /* Bind the socket to an alternative local IP address */
196: if (options.bind_address == NULL)
197: return sock;
198:
199: memset(&hints, 0, sizeof(hints));
1.114 markus 200: hints.ai_family = family;
1.105 markus 201: hints.ai_socktype = SOCK_STREAM;
202: hints.ai_flags = AI_PASSIVE;
203: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
204: if (gaierr) {
205: error("getaddrinfo: %s: %s", options.bind_address,
206: gai_strerror(gaierr));
207: close(sock);
208: return -1;
209: }
210: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
211: error("bind: %s: %s", options.bind_address, strerror(errno));
212: close(sock);
213: freeaddrinfo(res);
214: return -1;
1.38 markus 215: }
1.105 markus 216: freeaddrinfo(res);
1.38 markus 217: return sock;
1.1 deraadt 218: }
219:
1.39 deraadt 220: /*
1.49 markus 221: * Opens a TCP/IP connection to the remote server on the given host.
222: * The address of the remote host will be returned in hostaddr.
223: * If port is 0, the default port will be used. If anonymous is zero,
1.39 deraadt 224: * a privileged port will be allocated to make the connection.
225: * This requires super-user privileges if anonymous is false.
226: * Connection_attempts specifies the maximum number of tries (one per
227: * second). If proxy_command is non-NULL, it specifies the command (with %h
228: * and %p substituted for host and port, respectively) to use to contact
229: * the daemon.
1.110 markus 230: * Return values:
231: * 0 for OK
232: * ECONNREFUSED if we got a "Connection Refused" by the peer on any address
233: * ECONNABORTED if we failed without a "Connection refused"
234: * Suitable error messages for the connection failure will already have been
235: * printed.
1.39 deraadt 236: */
1.38 markus 237: int
1.49 markus 238: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 239: u_short port, int family, int connection_attempts,
240: int anonymous, struct passwd *pw, const char *proxy_command)
1.1 deraadt 241: {
1.90 markus 242: int gaierr;
243: int on = 1;
1.49 markus 244: int sock = -1, attempt;
1.90 markus 245: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 246: struct addrinfo hints, *ai, *aitop;
1.38 markus 247: struct linger linger;
1.90 markus 248: struct servent *sp;
1.110 markus 249: /*
250: * Did we get only other errors than "Connection refused" (which
251: * should block fallback to rsh and similar), or did we get at least
252: * one "Connection refused"?
253: */
254: int full_failure = 1;
1.38 markus 255:
1.77 deraadt 256: debug("ssh_connect: getuid %u geteuid %u anon %d",
257: (u_int) getuid(), (u_int) geteuid(), anonymous);
1.38 markus 258:
259: /* Get default port if port has not been set. */
260: if (port == 0) {
261: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
262: if (sp)
263: port = ntohs(sp->s_port);
264: else
265: port = SSH_DEFAULT_PORT;
266: }
267: /* If a proxy command is given, connect using it. */
268: if (proxy_command != NULL)
1.103 markus 269: return ssh_proxy_connect(host, port, pw, proxy_command);
1.38 markus 270:
271: /* No proxy command. */
272:
1.49 markus 273: memset(&hints, 0, sizeof(hints));
1.115 markus 274: hints.ai_family = family;
1.49 markus 275: hints.ai_socktype = SOCK_STREAM;
276: snprintf(strport, sizeof strport, "%d", port);
277: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 278: fatal("%s: %.100s: %s", __progname, host,
279: gai_strerror(gaierr));
1.38 markus 280:
1.46 markus 281: /*
282: * Try to connect several times. On some machines, the first time
283: * will sometimes fail. In general socket code appears to behave
284: * quite magically on many machines.
1.110 markus 285: */
286: for (attempt = 0; ;) {
1.38 markus 287: if (attempt > 0)
288: debug("Trying again...");
289:
1.49 markus 290: /* Loop through addresses for this host, and try each one in
1.68 markus 291: sequence until the connection succeeds. */
1.49 markus 292: for (ai = aitop; ai; ai = ai->ai_next) {
293: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
294: continue;
295: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
296: ntop, sizeof(ntop), strport, sizeof(strport),
297: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
298: error("ssh_connect: getnameinfo failed");
299: continue;
300: }
301: debug("Connecting to %.200s [%.100s] port %s.",
302: host, ntop, strport);
303:
304: /* Create a socket for connecting. */
1.103 markus 305: sock = ssh_create_socket(pw,
1.80 markus 306: !anonymous && geteuid() == 0,
1.49 markus 307: ai->ai_family);
308: if (sock < 0)
1.110 markus 309: /* Any error is already output */
1.49 markus 310: continue;
311:
312: /* Connect to the host. We use the user's uid in the
313: * hope that it will help with tcp_wrappers showing
314: * the remote uid as root.
1.40 markus 315: */
1.103 markus 316: temporarily_use_uid(pw);
1.49 markus 317: if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
318: /* Successful connection. */
1.102 markus 319: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 320: restore_uid();
321: break;
1.49 markus 322: } else {
1.110 markus 323: if (errno == ECONNREFUSED)
324: full_failure = 0;
325: log("ssh: connect to address %s port %s: %s",
326: sockaddr_ntop(ai->ai_addr), strport,
327: strerror(errno));
1.38 markus 328: restore_uid();
1.40 markus 329: /*
330: * Close the failed socket; there appear to
331: * be some problems when reusing a socket for
332: * which connect() has already returned an
333: * error.
334: */
1.38 markus 335: close(sock);
336: }
337: }
1.49 markus 338: if (ai)
339: break; /* Successful connection. */
1.1 deraadt 340:
1.110 markus 341: attempt++;
342: if (attempt >= connection_attempts)
343: break;
1.38 markus 344: /* Sleep a moment before retrying. */
345: sleep(1);
346: }
1.49 markus 347:
348: freeaddrinfo(aitop);
349:
1.38 markus 350: /* Return failure if we didn't get a successful connection. */
351: if (attempt >= connection_attempts)
1.110 markus 352: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.38 markus 353:
354: debug("Connection established.");
355:
1.40 markus 356: /*
357: * Set socket options. We would like the socket to disappear as soon
358: * as it has been closed for whatever reason.
359: */
360: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.38 markus 361: linger.l_onoff = 1;
362: linger.l_linger = 5;
1.90 markus 363: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
364:
365: /* Set keepalives if requested. */
366: if (options.keepalives &&
367: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
368: sizeof(on)) < 0)
369: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 370:
371: /* Set the connection. */
372: packet_set_connection(sock, sock);
1.1 deraadt 373:
1.110 markus 374: return 0;
1.59 markus 375: }
376:
1.43 markus 377: /*
1.39 deraadt 378: * Waits for the server identification string, and sends our own
379: * identification string.
380: */
1.109 itojun 381: static void
1.95 itojun 382: ssh_exchange_identification(void)
1.1 deraadt 383: {
1.38 markus 384: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 385: int remote_major, remote_minor, i, mismatch;
1.38 markus 386: int connection_in = packet_get_connection_in();
387: int connection_out = packet_get_connection_out();
1.93 stevesk 388: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 389:
390: /* Read other side\'s version identification. */
1.75 markus 391: for (;;) {
392: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 393: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 394: if (len < 0)
395: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
396: if (len != 1)
397: fatal("ssh_exchange_identification: Connection closed by remote host");
398: if (buf[i] == '\r') {
399: buf[i] = '\n';
400: buf[i + 1] = 0;
401: continue; /**XXX wait for \n */
402: }
403: if (buf[i] == '\n') {
404: buf[i + 1] = 0;
405: break;
406: }
1.38 markus 407: }
1.75 markus 408: buf[sizeof(buf) - 1] = 0;
1.76 markus 409: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 410: break;
1.75 markus 411: debug("ssh_exchange_identification: %s", buf);
1.38 markus 412: }
1.59 markus 413: server_version_string = xstrdup(buf);
1.38 markus 414:
1.40 markus 415: /*
416: * Check that the versions match. In future this might accept
417: * several versions and set appropriate flags to handle them.
418: */
1.59 markus 419: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
420: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 421: fatal("Bad remote protocol version identification: '%.100s'", buf);
422: debug("Remote protocol version %d.%d, remote software version %.100s",
423: remote_major, remote_minor, remote_version);
424:
1.59 markus 425: compat_datafellows(remote_version);
1.64 markus 426: mismatch = 0;
1.59 markus 427:
1.116 deraadt 428: switch (remote_major) {
1.64 markus 429: case 1:
430: if (remote_minor == 99 &&
431: (options.protocol & SSH_PROTO_2) &&
432: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
433: enable_compat20();
434: break;
435: }
436: if (!(options.protocol & SSH_PROTO_1)) {
437: mismatch = 1;
438: break;
439: }
440: if (remote_minor < 3) {
441: fatal("Remote machine has too old SSH software version.");
1.81 markus 442: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 443: /* We speak 1.3, too. */
444: enable_compat13();
1.81 markus 445: minor1 = 3;
1.64 markus 446: if (options.forward_agent) {
447: log("Agent forwarding disabled for protocol 1.3");
448: options.forward_agent = 0;
449: }
450: }
451: break;
452: case 2:
453: if (options.protocol & SSH_PROTO_2) {
454: enable_compat20();
455: break;
1.38 markus 456: }
1.64 markus 457: /* FALLTHROUGH */
1.68 markus 458: default:
1.64 markus 459: mismatch = 1;
460: break;
1.38 markus 461: }
1.64 markus 462: if (mismatch)
1.38 markus 463: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 464: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
465: remote_major);
1.38 markus 466: /* Send our own protocol version identification. */
467: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 468: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 469: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 470: SSH_VERSION);
1.45 deraadt 471: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 472: fatal("write: %.100s", strerror(errno));
1.59 markus 473: client_version_string = xstrdup(buf);
474: chop(client_version_string);
475: chop(server_version_string);
476: debug("Local version string %.100s", client_version_string);
1.1 deraadt 477: }
478:
1.96 markus 479: /* defaults to 'no' */
1.109 itojun 480: static int
1.112 markus 481: confirm(const char *prompt)
1.1 deraadt 482: {
1.38 markus 483: char buf[1024];
484: FILE *f;
485: int retval = -1;
1.96 markus 486:
487: if (options.batch_mode)
488: return 0;
1.88 markus 489: if (isatty(STDIN_FILENO))
1.38 markus 490: f = stdin;
491: else
1.95 itojun 492: f = fopen(_PATH_TTY, "rw");
1.38 markus 493: if (f == NULL)
494: return 0;
495: fflush(stdout);
1.113 markus 496: fprintf(stderr, "%s", prompt);
1.38 markus 497: while (1) {
498: if (fgets(buf, sizeof(buf), f) == NULL) {
499: fprintf(stderr, "\n");
500: strlcpy(buf, "no", sizeof buf);
501: }
502: /* Remove newline from response. */
503: if (strchr(buf, '\n'))
504: *strchr(buf, '\n') = 0;
505: if (strcmp(buf, "yes") == 0)
506: retval = 1;
1.79 markus 507: else if (strcmp(buf, "no") == 0)
1.38 markus 508: retval = 0;
1.79 markus 509: else
1.113 markus 510: fprintf(stderr, "Please type 'yes' or 'no': ");
1.38 markus 511:
512: if (retval != -1) {
513: if (f != stdin)
514: fclose(f);
515: return retval;
516: }
1.1 deraadt 517: }
518: }
519:
1.39 deraadt 520: /*
1.108 markus 521: * check whether the supplied host key is valid, return -1 if the key
522: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 523: */
1.46 markus 524:
1.109 itojun 525: static int
1.70 markus 526: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 527: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 528: {
1.58 markus 529: Key *file_key;
1.72 markus 530: char *type = key_type(host_key);
1.46 markus 531: char *ip = NULL;
1.100 markus 532: char hostline[1000], *hostp, *fp;
1.38 markus 533: HostStatus host_status;
534: HostStatus ip_status;
1.49 markus 535: int local = 0, host_ip_differ = 0;
536: char ntop[NI_MAXHOST];
1.88 markus 537: int host_line, ip_line;
1.85 markus 538: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 539:
540: /*
541: * Force accepting of the host key for loopback/localhost. The
542: * problem is that if the home directory is NFS-mounted to multiple
543: * machines, localhost will refer to a different machine in each of
544: * them, and the user will get bogus HOST_CHANGED warnings. This
545: * essentially disables host authentication for localhost; however,
546: * this is probably not a real problem.
547: */
1.70 markus 548: /** hostaddr == 0! */
1.49 markus 549: switch (hostaddr->sa_family) {
550: case AF_INET:
1.108 markus 551: local = (ntohl(((struct sockaddr_in *)hostaddr)->
552: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 553: break;
554: case AF_INET6:
1.108 markus 555: local = IN6_IS_ADDR_LOOPBACK(
556: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 557: break;
558: default:
559: local = 0;
560: break;
561: }
1.111 markus 562: if (options.no_host_authentication_for_localhost == 1 && local &&
563: options.host_key_alias == NULL) {
1.88 markus 564: debug("Forcing accepting of host key for "
565: "loopback/localhost.");
1.108 markus 566: return 0;
1.49 markus 567: }
1.42 markus 568:
569: /*
1.88 markus 570: * We don't have the remote ip-address for connections
571: * using a proxy command
1.42 markus 572: */
1.84 markus 573: if (options.proxy_command == NULL) {
574: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 575: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 576: fatal("check_host_key: getnameinfo failed");
577: ip = xstrdup(ntop);
578: } else {
579: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 580: }
1.88 markus 581: /*
582: * Turn off check_host_ip if the connection is to localhost, via proxy
583: * command or if we don't have a hostname to compare with
584: */
585: if (options.check_host_ip &&
586: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
587: options.check_host_ip = 0;
1.86 markus 588:
589: /*
590: * Allow the user to record the key under a different name. This is
591: * useful for ssh tunneling over forwarded connections or if you run
592: * multiple sshd's on different ports on the same machine.
593: */
594: if (options.host_key_alias != NULL) {
595: host = options.host_key_alias;
596: debug("using hostkeyalias: %s", host);
1.84 markus 597: }
1.38 markus 598:
1.46 markus 599: /*
600: * Store the host key from the known host file in here so that we can
601: * compare it with the key for the IP address.
602: */
1.58 markus 603: file_key = key_new(host_key->type);
1.38 markus 604:
1.40 markus 605: /*
606: * Check if the host key is present in the user\'s list of known
607: * hosts or in the systemwide list.
608: */
1.85 markus 609: host_file = user_hostfile;
1.108 markus 610: host_status = check_host_in_hostfile(host_file, host, host_key,
611: file_key, &host_line);
1.85 markus 612: if (host_status == HOST_NEW) {
613: host_file = system_hostfile;
1.108 markus 614: host_status = check_host_in_hostfile(host_file, host, host_key,
615: file_key, &host_line);
1.85 markus 616: }
1.40 markus 617: /*
618: * Also perform check for the ip address, skip the check if we are
619: * localhost or the hostname was an ip address to begin with
620: */
1.88 markus 621: if (options.check_host_ip) {
1.58 markus 622: Key *ip_key = key_new(host_key->type);
1.38 markus 623:
1.85 markus 624: ip_file = user_hostfile;
1.108 markus 625: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
626: ip_key, &ip_line);
1.85 markus 627: if (ip_status == HOST_NEW) {
628: ip_file = system_hostfile;
1.108 markus 629: ip_status = check_host_in_hostfile(ip_file, ip,
630: host_key, ip_key, &ip_line);
1.85 markus 631: }
1.38 markus 632: if (host_status == HOST_CHANGED &&
1.58 markus 633: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 634: host_ip_differ = 1;
635:
1.58 markus 636: key_free(ip_key);
1.38 markus 637: } else
638: ip_status = host_status;
639:
1.58 markus 640: key_free(file_key);
1.38 markus 641:
642: switch (host_status) {
643: case HOST_OK:
644: /* The host is known and the key matches. */
1.72 markus 645: debug("Host '%.200s' is known and matches the %s host key.",
646: host, type);
1.85 markus 647: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 648: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 649: if (readonly)
650: log("%s host key for IP address "
651: "'%.128s' not in list of known hosts.",
652: type, ip);
653: else if (!add_host_to_hostfile(user_hostfile, ip,
654: host_key))
655: log("Failed to add the %s host key for IP "
656: "address '%.128s' to the list of known "
657: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 658: else
1.108 markus 659: log("Warning: Permanently added the %s host "
660: "key for IP address '%.128s' to the list "
661: "of known hosts.", type, ip);
1.38 markus 662: }
663: break;
664: case HOST_NEW:
1.108 markus 665: if (readonly)
666: goto fail;
1.38 markus 667: /* The host is new. */
668: if (options.strict_host_key_checking == 1) {
1.108 markus 669: /*
670: * User has requested strict host key checking. We
671: * will not add the host key automatically. The only
672: * alternative left is to abort.
673: */
674: error("No %s host key is known for %.200s and you "
675: "have requested strict checking.", type, host);
676: goto fail;
1.38 markus 677: } else if (options.strict_host_key_checking == 2) {
678: /* The default */
679: char prompt[1024];
1.100 markus 680: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 681: snprintf(prompt, sizeof(prompt),
1.108 markus 682: "The authenticity of host '%.200s (%s)' can't be "
683: "established.\n"
1.72 markus 684: "%s key fingerprint is %s.\n"
1.108 markus 685: "Are you sure you want to continue connecting "
686: "(yes/no)? ", host, ip, type, fp);
1.100 markus 687: xfree(fp);
1.112 markus 688: if (!confirm(prompt)) {
1.108 markus 689: goto fail;
690: }
1.38 markus 691: }
1.88 markus 692: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 693: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
694: hostp = hostline;
695: } else
696: hostp = host;
697:
1.108 markus 698: /*
699: * If not in strict mode, add the key automatically to the
700: * local known_hosts file.
701: */
1.70 markus 702: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.108 markus 703: log("Failed to add the host to the list of known "
704: "hosts (%.500s).", user_hostfile);
1.38 markus 705: else
1.108 markus 706: log("Warning: Permanently added '%.200s' (%s) to the "
707: "list of known hosts.", hostp, type);
1.38 markus 708: break;
709: case HOST_CHANGED:
710: if (options.check_host_ip && host_ip_differ) {
711: char *msg;
712: if (ip_status == HOST_NEW)
713: msg = "is unknown";
714: else if (ip_status == HOST_OK)
715: msg = "is unchanged";
716: else
717: msg = "has a different value";
718: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
719: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
720: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 721: error("The %s host key for %s has changed,", type, host);
1.38 markus 722: error("and the key for the according IP address %s", ip);
723: error("%s. This could either mean that", msg);
724: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 725: error("and its host key have changed at the same time.");
1.88 markus 726: if (ip_status != HOST_NEW)
1.85 markus 727: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 728: }
729: /* The host key has changed. */
1.100 markus 730: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 731: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 732: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 733: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
734: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
735: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 736: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 737: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.100 markus 738: type, fp);
1.38 markus 739: error("Please contact your system administrator.");
740: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 741: user_hostfile);
1.85 markus 742: error("Offending key in %s:%d", host_file, host_line);
1.100 markus 743: xfree(fp);
1.38 markus 744:
1.40 markus 745: /*
746: * If strict host key checking is in use, the user will have
747: * to edit the key manually and we can only abort.
748: */
1.108 markus 749: if (options.strict_host_key_checking) {
750: error("%s host key for %.200s has changed and you have "
751: "requested strict checking.", type, host);
752: goto fail;
753: }
1.38 markus 754:
1.40 markus 755: /*
756: * If strict host key checking has not been requested, allow
757: * the connection but without password authentication or
758: * agent forwarding.
759: */
1.38 markus 760: if (options.password_authentication) {
1.108 markus 761: error("Password authentication is disabled to avoid "
762: "man-in-the-middle attacks.");
1.38 markus 763: options.password_authentication = 0;
764: }
765: if (options.forward_agent) {
1.108 markus 766: error("Agent forwarding is disabled to avoid "
767: "man-in-the-middle attacks.");
1.38 markus 768: options.forward_agent = 0;
1.83 markus 769: }
770: if (options.forward_x11) {
1.108 markus 771: error("X11 forwarding is disabled to avoid "
772: "man-in-the-middle attacks.");
1.83 markus 773: options.forward_x11 = 0;
774: }
1.108 markus 775: if (options.num_local_forwards > 0 ||
776: options.num_remote_forwards > 0) {
777: error("Port forwarding is disabled to avoid "
778: "man-in-the-middle attacks.");
779: options.num_local_forwards =
780: options.num_remote_forwards = 0;
1.38 markus 781: }
1.40 markus 782: /*
783: * XXX Should permit the user to change to use the new id.
784: * This could be done by converting the host key to an
785: * identifying sentence, tell that the host identifies itself
786: * by that sentence, and ask the user if he/she whishes to
787: * accept the authentication.
788: */
1.38 markus 789: break;
1.88 markus 790: }
791:
792: if (options.check_host_ip && host_status != HOST_CHANGED &&
793: ip_status == HOST_CHANGED) {
794: log("Warning: the %s host key for '%.200s' "
1.94 itojun 795: "differs from the key for the IP address '%.128s'",
1.88 markus 796: type, host, ip);
797: if (host_status == HOST_OK)
798: log("Matching host key in %s:%d", host_file, host_line);
799: log("Offending key for IP in %s:%d", ip_file, ip_line);
800: if (options.strict_host_key_checking == 1) {
1.108 markus 801: error("Exiting, you have requested strict checking.");
802: goto fail;
1.88 markus 803: } else if (options.strict_host_key_checking == 2) {
1.112 markus 804: if (!confirm("Are you sure you want "
805: "to continue connecting (yes/no)? ")) {
1.108 markus 806: goto fail;
807: }
1.88 markus 808: }
1.38 markus 809: }
1.82 provos 810:
811: xfree(ip);
1.108 markus 812: return 0;
813:
814: fail:
815: xfree(ip);
816: return -1;
817: }
818:
819: int
820: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
821: {
822: struct stat st;
823:
824: /* return ok if the key can be found in an old keyfile */
825: if (stat(options.system_hostfile2, &st) == 0 ||
826: stat(options.user_hostfile2, &st) == 0) {
827: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
828: options.user_hostfile2, options.system_hostfile2) == 0)
829: return 0;
830: }
831: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
832: options.user_hostfile, options.system_hostfile);
1.51 markus 833: }
1.70 markus 834:
1.51 markus 835: /*
836: * Starts a dialog with the server, and authenticates the current user on the
837: * server. This does not need any extra privileges. The basic connection
838: * to the server must already have been established before this is called.
839: * If login fails, this function prints an error and never returns.
840: * This function does not require super-user privileges.
841: */
842: void
1.104 markus 843: ssh_login(Key **keys, int nkeys, const char *orighost,
1.103 markus 844: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 845: {
846: char *host, *cp;
1.70 markus 847: char *server_user, *local_user;
848:
849: local_user = xstrdup(pw->pw_name);
850: server_user = options.user ? options.user : local_user;
1.51 markus 851:
852: /* Convert the user-supplied hostname into all lowercase. */
853: host = xstrdup(orighost);
854: for (cp = host; *cp; cp++)
855: if (isupper(*cp))
856: *cp = tolower(*cp);
857:
858: /* Exchange protocol version identification strings with the server. */
859: ssh_exchange_identification();
860:
861: /* Put the connection into non-blocking mode. */
862: packet_set_nonblocking();
863:
864: /* key exchange */
865: /* authenticate user */
1.59 markus 866: if (compat20) {
867: ssh_kex2(host, hostaddr);
1.104 markus 868: ssh_userauth2(local_user, server_user, host, keys, nkeys);
1.59 markus 869: } else {
870: ssh_kex(host, hostaddr);
1.104 markus 871: ssh_userauth1(local_user, server_user, host, keys, nkeys);
1.59 markus 872: }
1.97 markus 873: }
874:
875: void
876: ssh_put_password(char *password)
877: {
878: int size;
879: char *padded;
880:
1.99 deraadt 881: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 882: packet_put_cstring(password);
1.99 deraadt 883: return;
884: }
1.97 markus 885: size = roundup(strlen(password) + 1, 32);
886: padded = xmalloc(size);
887: memset(padded, 0, size);
888: strlcpy(padded, password, size);
889: packet_put_string(padded, size);
890: memset(padded, 0, size);
891: xfree(padded);
1.1 deraadt 892: }
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