Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.108
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"
1.108 ! markus 16: RCSID("$OpenBSD: sshconnect.c,v 1.107 2001/06/07 20:23:05 markus 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:
41: /* AF_UNSPEC or AF_INET or AF_INET6 */
42: extern int IPv4or6;
1.43 markus 43:
1.39 deraadt 44: /*
45: * Connect to the given ssh server using a proxy command.
46: */
1.3 provos 47: int
1.103 markus 48: ssh_proxy_connect(const char *host, u_short port, struct passwd *pw,
1.3 provos 49: const char *proxy_command)
1.1 deraadt 50: {
1.38 markus 51: Buffer command;
52: const char *cp;
53: char *command_string;
54: int pin[2], pout[2];
1.69 deraadt 55: pid_t pid;
1.49 markus 56: char strport[NI_MAXSERV];
1.38 markus 57:
58: /* Convert the port number into a string. */
1.49 markus 59: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 60:
61: /* Build the final command string in the buffer by making the
62: appropriate substitutions to the given proxy command. */
63: buffer_init(&command);
64: for (cp = proxy_command; *cp; cp++) {
65: if (cp[0] == '%' && cp[1] == '%') {
66: buffer_append(&command, "%", 1);
67: cp++;
68: continue;
69: }
70: if (cp[0] == '%' && cp[1] == 'h') {
71: buffer_append(&command, host, strlen(host));
72: cp++;
73: continue;
74: }
75: if (cp[0] == '%' && cp[1] == 'p') {
1.49 markus 76: buffer_append(&command, strport, strlen(strport));
1.38 markus 77: cp++;
78: continue;
79: }
80: buffer_append(&command, cp, 1);
81: }
82: buffer_append(&command, "\0", 1);
83:
84: /* Get the final command string. */
85: command_string = buffer_ptr(&command);
86:
87: /* Create pipes for communicating with the proxy. */
88: if (pipe(pin) < 0 || pipe(pout) < 0)
89: fatal("Could not create pipes to communicate with the proxy: %.100s",
90: strerror(errno));
91:
92: debug("Executing proxy command: %.500s", command_string);
93:
94: /* Fork and execute the proxy command. */
95: if ((pid = fork()) == 0) {
96: char *argv[10];
97:
98: /* Child. Permanently give up superuser privileges. */
1.103 markus 99: permanently_set_uid(pw);
1.38 markus 100:
101: /* Redirect stdin and stdout. */
102: close(pin[1]);
103: if (pin[0] != 0) {
104: if (dup2(pin[0], 0) < 0)
105: perror("dup2 stdin");
106: close(pin[0]);
107: }
108: close(pout[0]);
109: if (dup2(pout[1], 1) < 0)
110: perror("dup2 stdout");
111: /* Cannot be 1 because pin allocated two descriptors. */
112: close(pout[1]);
113:
114: /* Stderr is left as it is so that error messages get
115: printed on the user's terminal. */
1.89 markus 116: argv[0] = _PATH_BSHELL;
1.38 markus 117: argv[1] = "-c";
118: argv[2] = command_string;
119: argv[3] = NULL;
120:
121: /* Execute the proxy command. Note that we gave up any
122: extra privileges above. */
1.89 markus 123: execv(argv[0], argv);
124: perror(argv[0]);
1.38 markus 125: exit(1);
126: }
127: /* Parent. */
128: if (pid < 0)
129: fatal("fork failed: %.100s", strerror(errno));
130:
131: /* Close child side of the descriptors. */
132: close(pin[0]);
133: close(pout[1]);
134:
135: /* Free the command name. */
136: buffer_free(&command);
137:
138: /* Set the connection file descriptors. */
139: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 140:
1.38 markus 141: return 1;
1.1 deraadt 142: }
143:
1.39 deraadt 144: /*
145: * Creates a (possibly privileged) socket for use as the ssh connection.
146: */
1.38 markus 147: int
1.103 markus 148: ssh_create_socket(struct passwd *pw, int privileged, int family)
1.1 deraadt 149: {
1.105 markus 150: int sock, gaierr;
151: struct addrinfo hints, *res;
1.1 deraadt 152:
1.40 markus 153: /*
154: * If we are running as root and want to connect to a privileged
155: * port, bind our own socket to a privileged port.
156: */
1.38 markus 157: if (privileged) {
158: int p = IPPORT_RESERVED - 1;
1.49 markus 159: sock = rresvport_af(&p, family);
1.38 markus 160: if (sock < 0)
1.55 markus 161: error("rresvport: af=%d %.100s", family, strerror(errno));
162: else
163: debug("Allocated local port %d.", p);
1.105 markus 164: return sock;
165: }
166: /*
167: * Just create an ordinary socket on arbitrary port. We use
168: * the user's uid to create the socket.
169: */
170: temporarily_use_uid(pw);
171: sock = socket(family, SOCK_STREAM, 0);
172: if (sock < 0)
173: error("socket: %.100s", strerror(errno));
174: restore_uid();
175:
176: /* Bind the socket to an alternative local IP address */
177: if (options.bind_address == NULL)
178: return sock;
179:
180: memset(&hints, 0, sizeof(hints));
181: hints.ai_family = IPv4or6;
182: hints.ai_socktype = SOCK_STREAM;
183: hints.ai_flags = AI_PASSIVE;
184: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
185: if (gaierr) {
186: error("getaddrinfo: %s: %s", options.bind_address,
187: gai_strerror(gaierr));
188: close(sock);
189: return -1;
190: }
191: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
192: error("bind: %s: %s", options.bind_address, strerror(errno));
193: close(sock);
194: freeaddrinfo(res);
195: return -1;
1.38 markus 196: }
1.105 markus 197: freeaddrinfo(res);
1.38 markus 198: return sock;
1.1 deraadt 199: }
200:
1.39 deraadt 201: /*
1.49 markus 202: * Opens a TCP/IP connection to the remote server on the given host.
203: * The address of the remote host will be returned in hostaddr.
204: * If port is 0, the default port will be used. If anonymous is zero,
1.39 deraadt 205: * a privileged port will be allocated to make the connection.
206: * This requires super-user privileges if anonymous is false.
207: * Connection_attempts specifies the maximum number of tries (one per
208: * second). If proxy_command is non-NULL, it specifies the command (with %h
209: * and %p substituted for host and port, respectively) to use to contact
210: * the daemon.
211: */
1.38 markus 212: int
1.49 markus 213: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.41 markus 214: u_short port, int connection_attempts,
1.103 markus 215: int anonymous, struct passwd *pw,
1.38 markus 216: const char *proxy_command)
1.1 deraadt 217: {
1.90 markus 218: int gaierr;
219: int on = 1;
1.49 markus 220: int sock = -1, attempt;
1.90 markus 221: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 222: struct addrinfo hints, *ai, *aitop;
1.38 markus 223: struct linger linger;
1.90 markus 224: struct servent *sp;
1.38 markus 225:
1.77 deraadt 226: debug("ssh_connect: getuid %u geteuid %u anon %d",
227: (u_int) getuid(), (u_int) geteuid(), anonymous);
1.38 markus 228:
229: /* Get default port if port has not been set. */
230: if (port == 0) {
231: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
232: if (sp)
233: port = ntohs(sp->s_port);
234: else
235: port = SSH_DEFAULT_PORT;
236: }
237: /* If a proxy command is given, connect using it. */
238: if (proxy_command != NULL)
1.103 markus 239: return ssh_proxy_connect(host, port, pw, proxy_command);
1.38 markus 240:
241: /* No proxy command. */
242:
1.49 markus 243: memset(&hints, 0, sizeof(hints));
244: hints.ai_family = IPv4or6;
245: hints.ai_socktype = SOCK_STREAM;
246: snprintf(strport, sizeof strport, "%d", port);
247: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 248: fatal("%s: %.100s: %s", __progname, host,
249: gai_strerror(gaierr));
1.38 markus 250:
1.46 markus 251: /*
252: * Try to connect several times. On some machines, the first time
253: * will sometimes fail. In general socket code appears to behave
254: * quite magically on many machines.
255: */
1.38 markus 256: for (attempt = 0; attempt < connection_attempts; attempt++) {
257: if (attempt > 0)
258: debug("Trying again...");
259:
1.49 markus 260: /* Loop through addresses for this host, and try each one in
1.68 markus 261: sequence until the connection succeeds. */
1.49 markus 262: for (ai = aitop; ai; ai = ai->ai_next) {
263: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
264: continue;
265: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
266: ntop, sizeof(ntop), strport, sizeof(strport),
267: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
268: error("ssh_connect: getnameinfo failed");
269: continue;
270: }
271: debug("Connecting to %.200s [%.100s] port %s.",
272: host, ntop, strport);
273:
274: /* Create a socket for connecting. */
1.103 markus 275: sock = ssh_create_socket(pw,
1.80 markus 276: !anonymous && geteuid() == 0,
1.49 markus 277: ai->ai_family);
278: if (sock < 0)
279: continue;
280:
281: /* Connect to the host. We use the user's uid in the
282: * hope that it will help with tcp_wrappers showing
283: * the remote uid as root.
1.40 markus 284: */
1.103 markus 285: temporarily_use_uid(pw);
1.49 markus 286: if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
287: /* Successful connection. */
1.102 markus 288: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 289: restore_uid();
290: break;
1.49 markus 291: } else {
1.38 markus 292: debug("connect: %.100s", strerror(errno));
293: restore_uid();
1.40 markus 294: /*
295: * Close the failed socket; there appear to
296: * be some problems when reusing a socket for
297: * which connect() has already returned an
298: * error.
299: */
1.38 markus 300: shutdown(sock, SHUT_RDWR);
301: close(sock);
302: }
303: }
1.49 markus 304: if (ai)
305: break; /* Successful connection. */
1.1 deraadt 306:
1.38 markus 307: /* Sleep a moment before retrying. */
308: sleep(1);
309: }
1.49 markus 310:
311: freeaddrinfo(aitop);
312:
1.38 markus 313: /* Return failure if we didn't get a successful connection. */
314: if (attempt >= connection_attempts)
315: return 0;
316:
317: debug("Connection established.");
318:
1.40 markus 319: /*
320: * Set socket options. We would like the socket to disappear as soon
321: * as it has been closed for whatever reason.
322: */
323: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.38 markus 324: linger.l_onoff = 1;
325: linger.l_linger = 5;
1.90 markus 326: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
327:
328: /* Set keepalives if requested. */
329: if (options.keepalives &&
330: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
331: sizeof(on)) < 0)
332: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 333:
334: /* Set the connection. */
335: packet_set_connection(sock, sock);
1.1 deraadt 336:
1.38 markus 337: return 1;
1.59 markus 338: }
339:
1.43 markus 340: /*
1.39 deraadt 341: * Waits for the server identification string, and sends our own
342: * identification string.
343: */
1.38 markus 344: void
1.95 itojun 345: ssh_exchange_identification(void)
1.1 deraadt 346: {
1.38 markus 347: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 348: int remote_major, remote_minor, i, mismatch;
1.38 markus 349: int connection_in = packet_get_connection_in();
350: int connection_out = packet_get_connection_out();
1.93 stevesk 351: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 352:
353: /* Read other side\'s version identification. */
1.75 markus 354: for (;;) {
355: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 356: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 357: if (len < 0)
358: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
359: if (len != 1)
360: fatal("ssh_exchange_identification: Connection closed by remote host");
361: if (buf[i] == '\r') {
362: buf[i] = '\n';
363: buf[i + 1] = 0;
364: continue; /**XXX wait for \n */
365: }
366: if (buf[i] == '\n') {
367: buf[i + 1] = 0;
368: break;
369: }
1.38 markus 370: }
1.75 markus 371: buf[sizeof(buf) - 1] = 0;
1.76 markus 372: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 373: break;
1.75 markus 374: debug("ssh_exchange_identification: %s", buf);
1.38 markus 375: }
1.59 markus 376: server_version_string = xstrdup(buf);
1.38 markus 377:
1.40 markus 378: /*
379: * Check that the versions match. In future this might accept
380: * several versions and set appropriate flags to handle them.
381: */
1.59 markus 382: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
383: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 384: fatal("Bad remote protocol version identification: '%.100s'", buf);
385: debug("Remote protocol version %d.%d, remote software version %.100s",
386: remote_major, remote_minor, remote_version);
387:
1.59 markus 388: compat_datafellows(remote_version);
1.64 markus 389: mismatch = 0;
1.59 markus 390:
1.64 markus 391: switch(remote_major) {
392: case 1:
393: if (remote_minor == 99 &&
394: (options.protocol & SSH_PROTO_2) &&
395: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
396: enable_compat20();
397: break;
398: }
399: if (!(options.protocol & SSH_PROTO_1)) {
400: mismatch = 1;
401: break;
402: }
403: if (remote_minor < 3) {
404: fatal("Remote machine has too old SSH software version.");
1.81 markus 405: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 406: /* We speak 1.3, too. */
407: enable_compat13();
1.81 markus 408: minor1 = 3;
1.64 markus 409: if (options.forward_agent) {
410: log("Agent forwarding disabled for protocol 1.3");
411: options.forward_agent = 0;
412: }
413: }
414: break;
415: case 2:
416: if (options.protocol & SSH_PROTO_2) {
417: enable_compat20();
418: break;
1.38 markus 419: }
1.64 markus 420: /* FALLTHROUGH */
1.68 markus 421: default:
1.64 markus 422: mismatch = 1;
423: break;
1.38 markus 424: }
1.64 markus 425: if (mismatch)
1.38 markus 426: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 427: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
428: remote_major);
1.38 markus 429: /* Send our own protocol version identification. */
430: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 431: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 432: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 433: SSH_VERSION);
1.45 deraadt 434: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 435: fatal("write: %.100s", strerror(errno));
1.59 markus 436: client_version_string = xstrdup(buf);
437: chop(client_version_string);
438: chop(server_version_string);
439: debug("Local version string %.100s", client_version_string);
1.1 deraadt 440: }
441:
1.96 markus 442: /* defaults to 'no' */
1.38 markus 443: int
444: read_yes_or_no(const char *prompt, int defval)
1.1 deraadt 445: {
1.38 markus 446: char buf[1024];
447: FILE *f;
448: int retval = -1;
1.96 markus 449:
450: if (options.batch_mode)
451: return 0;
1.38 markus 452:
1.88 markus 453: if (isatty(STDIN_FILENO))
1.38 markus 454: f = stdin;
455: else
1.95 itojun 456: f = fopen(_PATH_TTY, "rw");
1.38 markus 457:
458: if (f == NULL)
459: return 0;
460:
461: fflush(stdout);
462:
463: while (1) {
464: fprintf(stderr, "%s", prompt);
465: if (fgets(buf, sizeof(buf), f) == NULL) {
1.108 ! markus 466: /*
! 467: * Print a newline (the prompt probably didn\'t have
! 468: * one).
! 469: */
1.38 markus 470: fprintf(stderr, "\n");
471: strlcpy(buf, "no", sizeof buf);
472: }
473: /* Remove newline from response. */
474: if (strchr(buf, '\n'))
475: *strchr(buf, '\n') = 0;
476:
477: if (buf[0] == 0)
478: retval = defval;
479: if (strcmp(buf, "yes") == 0)
480: retval = 1;
1.79 markus 481: else if (strcmp(buf, "no") == 0)
1.38 markus 482: retval = 0;
1.79 markus 483: else
484: fprintf(stderr, "Please type 'yes' or 'no'.\n");
1.38 markus 485:
486: if (retval != -1) {
487: if (f != stdin)
488: fclose(f);
489: return retval;
490: }
1.1 deraadt 491: }
492: }
493:
1.39 deraadt 494: /*
1.108 ! markus 495: * check whether the supplied host key is valid, return -1 if the key
! 496: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 497: */
1.46 markus 498:
1.108 ! markus 499: int
1.70 markus 500: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 ! markus 501: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 502: {
1.58 markus 503: Key *file_key;
1.72 markus 504: char *type = key_type(host_key);
1.46 markus 505: char *ip = NULL;
1.100 markus 506: char hostline[1000], *hostp, *fp;
1.38 markus 507: HostStatus host_status;
508: HostStatus ip_status;
1.49 markus 509: int local = 0, host_ip_differ = 0;
510: char ntop[NI_MAXHOST];
1.88 markus 511: int host_line, ip_line;
1.85 markus 512: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 513:
514: /*
515: * Force accepting of the host key for loopback/localhost. The
516: * problem is that if the home directory is NFS-mounted to multiple
517: * machines, localhost will refer to a different machine in each of
518: * them, and the user will get bogus HOST_CHANGED warnings. This
519: * essentially disables host authentication for localhost; however,
520: * this is probably not a real problem.
521: */
1.70 markus 522: /** hostaddr == 0! */
1.49 markus 523: switch (hostaddr->sa_family) {
524: case AF_INET:
1.108 ! markus 525: local = (ntohl(((struct sockaddr_in *)hostaddr)->
! 526: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 527: break;
528: case AF_INET6:
1.108 ! markus 529: local = IN6_IS_ADDR_LOOPBACK(
! 530: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 531: break;
532: default:
533: local = 0;
534: break;
535: }
1.88 markus 536: if (local && options.host_key_alias == NULL) {
537: debug("Forcing accepting of host key for "
538: "loopback/localhost.");
1.108 ! markus 539: return 0;
1.49 markus 540: }
1.42 markus 541:
542: /*
1.88 markus 543: * We don't have the remote ip-address for connections
544: * using a proxy command
1.42 markus 545: */
1.84 markus 546: if (options.proxy_command == NULL) {
547: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 548: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 549: fatal("check_host_key: getnameinfo failed");
550: ip = xstrdup(ntop);
551: } else {
552: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 553: }
1.88 markus 554: /*
555: * Turn off check_host_ip if the connection is to localhost, via proxy
556: * command or if we don't have a hostname to compare with
557: */
558: if (options.check_host_ip &&
559: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
560: options.check_host_ip = 0;
1.86 markus 561:
562: /*
563: * Allow the user to record the key under a different name. This is
564: * useful for ssh tunneling over forwarded connections or if you run
565: * multiple sshd's on different ports on the same machine.
566: */
567: if (options.host_key_alias != NULL) {
568: host = options.host_key_alias;
569: debug("using hostkeyalias: %s", host);
1.84 markus 570: }
1.38 markus 571:
1.46 markus 572: /*
573: * Store the host key from the known host file in here so that we can
574: * compare it with the key for the IP address.
575: */
1.58 markus 576: file_key = key_new(host_key->type);
1.38 markus 577:
1.40 markus 578: /*
579: * Check if the host key is present in the user\'s list of known
580: * hosts or in the systemwide list.
581: */
1.85 markus 582: host_file = user_hostfile;
1.108 ! markus 583: host_status = check_host_in_hostfile(host_file, host, host_key,
! 584: file_key, &host_line);
1.85 markus 585: if (host_status == HOST_NEW) {
586: host_file = system_hostfile;
1.108 ! markus 587: host_status = check_host_in_hostfile(host_file, host, host_key,
! 588: file_key, &host_line);
1.85 markus 589: }
1.40 markus 590: /*
591: * Also perform check for the ip address, skip the check if we are
592: * localhost or the hostname was an ip address to begin with
593: */
1.88 markus 594: if (options.check_host_ip) {
1.58 markus 595: Key *ip_key = key_new(host_key->type);
1.38 markus 596:
1.85 markus 597: ip_file = user_hostfile;
1.108 ! markus 598: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
! 599: ip_key, &ip_line);
1.85 markus 600: if (ip_status == HOST_NEW) {
601: ip_file = system_hostfile;
1.108 ! markus 602: ip_status = check_host_in_hostfile(ip_file, ip,
! 603: host_key, ip_key, &ip_line);
1.85 markus 604: }
1.38 markus 605: if (host_status == HOST_CHANGED &&
1.58 markus 606: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 607: host_ip_differ = 1;
608:
1.58 markus 609: key_free(ip_key);
1.38 markus 610: } else
611: ip_status = host_status;
612:
1.58 markus 613: key_free(file_key);
1.38 markus 614:
615: switch (host_status) {
616: case HOST_OK:
617: /* The host is known and the key matches. */
1.72 markus 618: debug("Host '%.200s' is known and matches the %s host key.",
619: host, type);
1.85 markus 620: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 621: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 ! markus 622: if (readonly)
! 623: log("%s host key for IP address "
! 624: "'%.128s' not in list of known hosts.",
! 625: type, ip);
! 626: else if (!add_host_to_hostfile(user_hostfile, ip,
! 627: host_key))
! 628: log("Failed to add the %s host key for IP "
! 629: "address '%.128s' to the list of known "
! 630: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 631: else
1.108 ! markus 632: log("Warning: Permanently added the %s host "
! 633: "key for IP address '%.128s' to the list "
! 634: "of known hosts.", type, ip);
1.38 markus 635: }
636: break;
637: case HOST_NEW:
1.108 ! markus 638: if (readonly)
! 639: goto fail;
1.38 markus 640: /* The host is new. */
641: if (options.strict_host_key_checking == 1) {
1.108 ! markus 642: /*
! 643: * User has requested strict host key checking. We
! 644: * will not add the host key automatically. The only
! 645: * alternative left is to abort.
! 646: */
! 647: error("No %s host key is known for %.200s and you "
! 648: "have requested strict checking.", type, host);
! 649: goto fail;
1.38 markus 650: } else if (options.strict_host_key_checking == 2) {
651: /* The default */
652: char prompt[1024];
1.100 markus 653: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 654: snprintf(prompt, sizeof(prompt),
1.108 ! markus 655: "The authenticity of host '%.200s (%s)' can't be "
! 656: "established.\n"
1.72 markus 657: "%s key fingerprint is %s.\n"
1.108 ! markus 658: "Are you sure you want to continue connecting "
! 659: "(yes/no)? ", host, ip, type, fp);
1.100 markus 660: xfree(fp);
1.108 ! markus 661: if (!read_yes_or_no(prompt, -1)) {
! 662: log("Aborted by user!");
! 663: goto fail;
! 664: }
1.38 markus 665: }
1.88 markus 666: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 667: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
668: hostp = hostline;
669: } else
670: hostp = host;
671:
1.108 ! markus 672: /*
! 673: * If not in strict mode, add the key automatically to the
! 674: * local known_hosts file.
! 675: */
1.70 markus 676: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.108 ! markus 677: log("Failed to add the host to the list of known "
! 678: "hosts (%.500s).", user_hostfile);
1.38 markus 679: else
1.108 ! markus 680: log("Warning: Permanently added '%.200s' (%s) to the "
! 681: "list of known hosts.", hostp, type);
1.38 markus 682: break;
683: case HOST_CHANGED:
684: if (options.check_host_ip && host_ip_differ) {
685: char *msg;
686: if (ip_status == HOST_NEW)
687: msg = "is unknown";
688: else if (ip_status == HOST_OK)
689: msg = "is unchanged";
690: else
691: msg = "has a different value";
692: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
693: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
694: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 695: error("The %s host key for %s has changed,", type, host);
1.38 markus 696: error("and the key for the according IP address %s", ip);
697: error("%s. This could either mean that", msg);
698: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 699: error("and its host key have changed at the same time.");
1.88 markus 700: if (ip_status != HOST_NEW)
1.85 markus 701: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 702: }
703: /* The host key has changed. */
1.100 markus 704: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 705: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 706: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 707: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
708: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
709: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 710: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 711: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.100 markus 712: type, fp);
1.38 markus 713: error("Please contact your system administrator.");
714: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 715: user_hostfile);
1.85 markus 716: error("Offending key in %s:%d", host_file, host_line);
1.100 markus 717: xfree(fp);
1.38 markus 718:
1.40 markus 719: /*
720: * If strict host key checking is in use, the user will have
721: * to edit the key manually and we can only abort.
722: */
1.108 ! markus 723: if (options.strict_host_key_checking) {
! 724: error("%s host key for %.200s has changed and you have "
! 725: "requested strict checking.", type, host);
! 726: goto fail;
! 727: }
1.38 markus 728:
1.40 markus 729: /*
730: * If strict host key checking has not been requested, allow
731: * the connection but without password authentication or
732: * agent forwarding.
733: */
1.38 markus 734: if (options.password_authentication) {
1.108 ! markus 735: error("Password authentication is disabled to avoid "
! 736: "man-in-the-middle attacks.");
1.38 markus 737: options.password_authentication = 0;
738: }
739: if (options.forward_agent) {
1.108 ! markus 740: error("Agent forwarding is disabled to avoid "
! 741: "man-in-the-middle attacks.");
1.38 markus 742: options.forward_agent = 0;
1.83 markus 743: }
744: if (options.forward_x11) {
1.108 ! markus 745: error("X11 forwarding is disabled to avoid "
! 746: "man-in-the-middle attacks.");
1.83 markus 747: options.forward_x11 = 0;
748: }
1.108 ! markus 749: if (options.num_local_forwards > 0 ||
! 750: options.num_remote_forwards > 0) {
! 751: error("Port forwarding is disabled to avoid "
! 752: "man-in-the-middle attacks.");
! 753: options.num_local_forwards =
! 754: options.num_remote_forwards = 0;
1.38 markus 755: }
1.40 markus 756: /*
757: * XXX Should permit the user to change to use the new id.
758: * This could be done by converting the host key to an
759: * identifying sentence, tell that the host identifies itself
760: * by that sentence, and ask the user if he/she whishes to
761: * accept the authentication.
762: */
1.38 markus 763: break;
1.88 markus 764: }
765:
766: if (options.check_host_ip && host_status != HOST_CHANGED &&
767: ip_status == HOST_CHANGED) {
768: log("Warning: the %s host key for '%.200s' "
1.94 itojun 769: "differs from the key for the IP address '%.128s'",
1.88 markus 770: type, host, ip);
771: if (host_status == HOST_OK)
772: log("Matching host key in %s:%d", host_file, host_line);
773: log("Offending key for IP in %s:%d", ip_file, ip_line);
774: if (options.strict_host_key_checking == 1) {
1.108 ! markus 775: error("Exiting, you have requested strict checking.");
! 776: goto fail;
1.88 markus 777: } else if (options.strict_host_key_checking == 2) {
1.108 ! markus 778: if (!read_yes_or_no("Are you sure you want "
! 779: "to continue connecting (yes/no)? ", -1)) {
! 780: log("Aborted by user!");
! 781: goto fail;
! 782: }
1.88 markus 783: }
1.38 markus 784: }
1.82 provos 785:
786: xfree(ip);
1.108 ! markus 787: return 0;
! 788:
! 789: fail:
! 790: xfree(ip);
! 791: return -1;
! 792: }
! 793:
! 794: int
! 795: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
! 796: {
! 797: struct stat st;
! 798:
! 799: /* return ok if the key can be found in an old keyfile */
! 800: if (stat(options.system_hostfile2, &st) == 0 ||
! 801: stat(options.user_hostfile2, &st) == 0) {
! 802: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
! 803: options.user_hostfile2, options.system_hostfile2) == 0)
! 804: return 0;
! 805: }
! 806: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
! 807: options.user_hostfile, options.system_hostfile);
1.51 markus 808: }
1.70 markus 809:
1.51 markus 810: /*
811: * Starts a dialog with the server, and authenticates the current user on the
812: * server. This does not need any extra privileges. The basic connection
813: * to the server must already have been established before this is called.
814: * If login fails, this function prints an error and never returns.
815: * This function does not require super-user privileges.
816: */
817: void
1.104 markus 818: ssh_login(Key **keys, int nkeys, const char *orighost,
1.103 markus 819: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 820: {
821: char *host, *cp;
1.70 markus 822: char *server_user, *local_user;
823:
824: local_user = xstrdup(pw->pw_name);
825: server_user = options.user ? options.user : local_user;
1.51 markus 826:
827: /* Convert the user-supplied hostname into all lowercase. */
828: host = xstrdup(orighost);
829: for (cp = host; *cp; cp++)
830: if (isupper(*cp))
831: *cp = tolower(*cp);
832:
833: /* Exchange protocol version identification strings with the server. */
834: ssh_exchange_identification();
835:
836: /* Put the connection into non-blocking mode. */
837: packet_set_nonblocking();
838:
839: /* key exchange */
840: /* authenticate user */
1.59 markus 841: if (compat20) {
842: ssh_kex2(host, hostaddr);
1.104 markus 843: ssh_userauth2(local_user, server_user, host, keys, nkeys);
1.59 markus 844: } else {
845: ssh_kex(host, hostaddr);
1.104 markus 846: ssh_userauth1(local_user, server_user, host, keys, nkeys);
1.59 markus 847: }
1.97 markus 848: }
849:
850: void
851: ssh_put_password(char *password)
852: {
853: int size;
854: char *padded;
855:
1.99 deraadt 856: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 857: packet_put_cstring(password);
1.99 deraadt 858: return;
859: }
1.97 markus 860: size = roundup(strlen(password) + 1, 32);
861: padded = xmalloc(size);
862: memset(padded, 0, size);
863: strlcpy(padded, password, size);
864: packet_put_string(padded, size);
865: memset(padded, 0, size);
866: xfree(padded);
1.1 deraadt 867: }
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