Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.115
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"
1.115 ! markus 16: RCSID("$OpenBSD: sshconnect.c,v 1.114 2001/10/08 16:15:47 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:
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) {
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();
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: shutdown(sock, SHUT_RDWR);
336: close(sock);
337: }
338: }
1.49 markus 339: if (ai)
340: break; /* Successful connection. */
1.1 deraadt 341:
1.110 markus 342: attempt++;
343: if (attempt >= connection_attempts)
344: break;
1.38 markus 345: /* Sleep a moment before retrying. */
346: sleep(1);
347: }
1.49 markus 348:
349: freeaddrinfo(aitop);
350:
1.38 markus 351: /* Return failure if we didn't get a successful connection. */
352: if (attempt >= connection_attempts)
1.110 markus 353: return full_failure ? ECONNABORTED : ECONNREFUSED;
1.38 markus 354:
355: debug("Connection established.");
356:
1.40 markus 357: /*
358: * Set socket options. We would like the socket to disappear as soon
359: * as it has been closed for whatever reason.
360: */
361: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.38 markus 362: linger.l_onoff = 1;
363: linger.l_linger = 5;
1.90 markus 364: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
365:
366: /* Set keepalives if requested. */
367: if (options.keepalives &&
368: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
369: sizeof(on)) < 0)
370: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 371:
372: /* Set the connection. */
373: packet_set_connection(sock, sock);
1.1 deraadt 374:
1.110 markus 375: return 0;
1.59 markus 376: }
377:
1.43 markus 378: /*
1.39 deraadt 379: * Waits for the server identification string, and sends our own
380: * identification string.
381: */
1.109 itojun 382: static void
1.95 itojun 383: ssh_exchange_identification(void)
1.1 deraadt 384: {
1.38 markus 385: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 386: int remote_major, remote_minor, i, mismatch;
1.38 markus 387: int connection_in = packet_get_connection_in();
388: int connection_out = packet_get_connection_out();
1.93 stevesk 389: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 390:
391: /* Read other side\'s version identification. */
1.75 markus 392: for (;;) {
393: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 394: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 395: if (len < 0)
396: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
397: if (len != 1)
398: fatal("ssh_exchange_identification: Connection closed by remote host");
399: if (buf[i] == '\r') {
400: buf[i] = '\n';
401: buf[i + 1] = 0;
402: continue; /**XXX wait for \n */
403: }
404: if (buf[i] == '\n') {
405: buf[i + 1] = 0;
406: break;
407: }
1.38 markus 408: }
1.75 markus 409: buf[sizeof(buf) - 1] = 0;
1.76 markus 410: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 411: break;
1.75 markus 412: debug("ssh_exchange_identification: %s", buf);
1.38 markus 413: }
1.59 markus 414: server_version_string = xstrdup(buf);
1.38 markus 415:
1.40 markus 416: /*
417: * Check that the versions match. In future this might accept
418: * several versions and set appropriate flags to handle them.
419: */
1.59 markus 420: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
421: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 422: fatal("Bad remote protocol version identification: '%.100s'", buf);
423: debug("Remote protocol version %d.%d, remote software version %.100s",
424: remote_major, remote_minor, remote_version);
425:
1.59 markus 426: compat_datafellows(remote_version);
1.64 markus 427: mismatch = 0;
1.59 markus 428:
1.64 markus 429: switch(remote_major) {
430: case 1:
431: if (remote_minor == 99 &&
432: (options.protocol & SSH_PROTO_2) &&
433: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
434: enable_compat20();
435: break;
436: }
437: if (!(options.protocol & SSH_PROTO_1)) {
438: mismatch = 1;
439: break;
440: }
441: if (remote_minor < 3) {
442: fatal("Remote machine has too old SSH software version.");
1.81 markus 443: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 444: /* We speak 1.3, too. */
445: enable_compat13();
1.81 markus 446: minor1 = 3;
1.64 markus 447: if (options.forward_agent) {
448: log("Agent forwarding disabled for protocol 1.3");
449: options.forward_agent = 0;
450: }
451: }
452: break;
453: case 2:
454: if (options.protocol & SSH_PROTO_2) {
455: enable_compat20();
456: break;
1.38 markus 457: }
1.64 markus 458: /* FALLTHROUGH */
1.68 markus 459: default:
1.64 markus 460: mismatch = 1;
461: break;
1.38 markus 462: }
1.64 markus 463: if (mismatch)
1.38 markus 464: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 465: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
466: remote_major);
1.38 markus 467: /* Send our own protocol version identification. */
468: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 469: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 470: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 471: SSH_VERSION);
1.45 deraadt 472: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 473: fatal("write: %.100s", strerror(errno));
1.59 markus 474: client_version_string = xstrdup(buf);
475: chop(client_version_string);
476: chop(server_version_string);
477: debug("Local version string %.100s", client_version_string);
1.1 deraadt 478: }
479:
1.96 markus 480: /* defaults to 'no' */
1.109 itojun 481: static int
1.112 markus 482: confirm(const char *prompt)
1.1 deraadt 483: {
1.38 markus 484: char buf[1024];
485: FILE *f;
486: int retval = -1;
1.96 markus 487:
488: if (options.batch_mode)
489: return 0;
1.88 markus 490: if (isatty(STDIN_FILENO))
1.38 markus 491: f = stdin;
492: else
1.95 itojun 493: f = fopen(_PATH_TTY, "rw");
1.38 markus 494: if (f == NULL)
495: return 0;
496: fflush(stdout);
1.113 markus 497: fprintf(stderr, "%s", prompt);
1.38 markus 498: while (1) {
499: if (fgets(buf, sizeof(buf), f) == NULL) {
500: fprintf(stderr, "\n");
501: strlcpy(buf, "no", sizeof buf);
502: }
503: /* Remove newline from response. */
504: if (strchr(buf, '\n'))
505: *strchr(buf, '\n') = 0;
506: if (strcmp(buf, "yes") == 0)
507: retval = 1;
1.79 markus 508: else if (strcmp(buf, "no") == 0)
1.38 markus 509: retval = 0;
1.79 markus 510: else
1.113 markus 511: fprintf(stderr, "Please type 'yes' or 'no': ");
1.38 markus 512:
513: if (retval != -1) {
514: if (f != stdin)
515: fclose(f);
516: return retval;
517: }
1.1 deraadt 518: }
519: }
520:
1.39 deraadt 521: /*
1.108 markus 522: * check whether the supplied host key is valid, return -1 if the key
523: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 524: */
1.46 markus 525:
1.109 itojun 526: static int
1.70 markus 527: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 528: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 529: {
1.58 markus 530: Key *file_key;
1.72 markus 531: char *type = key_type(host_key);
1.46 markus 532: char *ip = NULL;
1.100 markus 533: char hostline[1000], *hostp, *fp;
1.38 markus 534: HostStatus host_status;
535: HostStatus ip_status;
1.49 markus 536: int local = 0, host_ip_differ = 0;
537: char ntop[NI_MAXHOST];
1.88 markus 538: int host_line, ip_line;
1.85 markus 539: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 540:
541: /*
542: * Force accepting of the host key for loopback/localhost. The
543: * problem is that if the home directory is NFS-mounted to multiple
544: * machines, localhost will refer to a different machine in each of
545: * them, and the user will get bogus HOST_CHANGED warnings. This
546: * essentially disables host authentication for localhost; however,
547: * this is probably not a real problem.
548: */
1.70 markus 549: /** hostaddr == 0! */
1.49 markus 550: switch (hostaddr->sa_family) {
551: case AF_INET:
1.108 markus 552: local = (ntohl(((struct sockaddr_in *)hostaddr)->
553: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 554: break;
555: case AF_INET6:
1.108 markus 556: local = IN6_IS_ADDR_LOOPBACK(
557: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 558: break;
559: default:
560: local = 0;
561: break;
562: }
1.111 markus 563: if (options.no_host_authentication_for_localhost == 1 && local &&
564: options.host_key_alias == NULL) {
1.88 markus 565: debug("Forcing accepting of host key for "
566: "loopback/localhost.");
1.108 markus 567: return 0;
1.49 markus 568: }
1.42 markus 569:
570: /*
1.88 markus 571: * We don't have the remote ip-address for connections
572: * using a proxy command
1.42 markus 573: */
1.84 markus 574: if (options.proxy_command == NULL) {
575: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 576: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 577: fatal("check_host_key: getnameinfo failed");
578: ip = xstrdup(ntop);
579: } else {
580: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 581: }
1.88 markus 582: /*
583: * Turn off check_host_ip if the connection is to localhost, via proxy
584: * command or if we don't have a hostname to compare with
585: */
586: if (options.check_host_ip &&
587: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
588: options.check_host_ip = 0;
1.86 markus 589:
590: /*
591: * Allow the user to record the key under a different name. This is
592: * useful for ssh tunneling over forwarded connections or if you run
593: * multiple sshd's on different ports on the same machine.
594: */
595: if (options.host_key_alias != NULL) {
596: host = options.host_key_alias;
597: debug("using hostkeyalias: %s", host);
1.84 markus 598: }
1.38 markus 599:
1.46 markus 600: /*
601: * Store the host key from the known host file in here so that we can
602: * compare it with the key for the IP address.
603: */
1.58 markus 604: file_key = key_new(host_key->type);
1.38 markus 605:
1.40 markus 606: /*
607: * Check if the host key is present in the user\'s list of known
608: * hosts or in the systemwide list.
609: */
1.85 markus 610: host_file = user_hostfile;
1.108 markus 611: host_status = check_host_in_hostfile(host_file, host, host_key,
612: file_key, &host_line);
1.85 markus 613: if (host_status == HOST_NEW) {
614: host_file = system_hostfile;
1.108 markus 615: host_status = check_host_in_hostfile(host_file, host, host_key,
616: file_key, &host_line);
1.85 markus 617: }
1.40 markus 618: /*
619: * Also perform check for the ip address, skip the check if we are
620: * localhost or the hostname was an ip address to begin with
621: */
1.88 markus 622: if (options.check_host_ip) {
1.58 markus 623: Key *ip_key = key_new(host_key->type);
1.38 markus 624:
1.85 markus 625: ip_file = user_hostfile;
1.108 markus 626: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
627: ip_key, &ip_line);
1.85 markus 628: if (ip_status == HOST_NEW) {
629: ip_file = system_hostfile;
1.108 markus 630: ip_status = check_host_in_hostfile(ip_file, ip,
631: host_key, ip_key, &ip_line);
1.85 markus 632: }
1.38 markus 633: if (host_status == HOST_CHANGED &&
1.58 markus 634: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 635: host_ip_differ = 1;
636:
1.58 markus 637: key_free(ip_key);
1.38 markus 638: } else
639: ip_status = host_status;
640:
1.58 markus 641: key_free(file_key);
1.38 markus 642:
643: switch (host_status) {
644: case HOST_OK:
645: /* The host is known and the key matches. */
1.72 markus 646: debug("Host '%.200s' is known and matches the %s host key.",
647: host, type);
1.85 markus 648: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 649: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 650: if (readonly)
651: log("%s host key for IP address "
652: "'%.128s' not in list of known hosts.",
653: type, ip);
654: else if (!add_host_to_hostfile(user_hostfile, ip,
655: host_key))
656: log("Failed to add the %s host key for IP "
657: "address '%.128s' to the list of known "
658: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 659: else
1.108 markus 660: log("Warning: Permanently added the %s host "
661: "key for IP address '%.128s' to the list "
662: "of known hosts.", type, ip);
1.38 markus 663: }
664: break;
665: case HOST_NEW:
1.108 markus 666: if (readonly)
667: goto fail;
1.38 markus 668: /* The host is new. */
669: if (options.strict_host_key_checking == 1) {
1.108 markus 670: /*
671: * User has requested strict host key checking. We
672: * will not add the host key automatically. The only
673: * alternative left is to abort.
674: */
675: error("No %s host key is known for %.200s and you "
676: "have requested strict checking.", type, host);
677: goto fail;
1.38 markus 678: } else if (options.strict_host_key_checking == 2) {
679: /* The default */
680: char prompt[1024];
1.100 markus 681: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 682: snprintf(prompt, sizeof(prompt),
1.108 markus 683: "The authenticity of host '%.200s (%s)' can't be "
684: "established.\n"
1.72 markus 685: "%s key fingerprint is %s.\n"
1.108 markus 686: "Are you sure you want to continue connecting "
687: "(yes/no)? ", host, ip, type, fp);
1.100 markus 688: xfree(fp);
1.112 markus 689: if (!confirm(prompt)) {
1.108 markus 690: goto fail;
691: }
1.38 markus 692: }
1.88 markus 693: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 694: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
695: hostp = hostline;
696: } else
697: hostp = host;
698:
1.108 markus 699: /*
700: * If not in strict mode, add the key automatically to the
701: * local known_hosts file.
702: */
1.70 markus 703: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.108 markus 704: log("Failed to add the host to the list of known "
705: "hosts (%.500s).", user_hostfile);
1.38 markus 706: else
1.108 markus 707: log("Warning: Permanently added '%.200s' (%s) to the "
708: "list of known hosts.", hostp, type);
1.38 markus 709: break;
710: case HOST_CHANGED:
711: if (options.check_host_ip && host_ip_differ) {
712: char *msg;
713: if (ip_status == HOST_NEW)
714: msg = "is unknown";
715: else if (ip_status == HOST_OK)
716: msg = "is unchanged";
717: else
718: msg = "has a different value";
719: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
720: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
721: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 722: error("The %s host key for %s has changed,", type, host);
1.38 markus 723: error("and the key for the according IP address %s", ip);
724: error("%s. This could either mean that", msg);
725: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 726: error("and its host key have changed at the same time.");
1.88 markus 727: if (ip_status != HOST_NEW)
1.85 markus 728: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 729: }
730: /* The host key has changed. */
1.100 markus 731: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.38 markus 732: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 733: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 734: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
735: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
736: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 737: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 738: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1.100 markus 739: type, fp);
1.38 markus 740: error("Please contact your system administrator.");
741: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 742: user_hostfile);
1.85 markus 743: error("Offending key in %s:%d", host_file, host_line);
1.100 markus 744: xfree(fp);
1.38 markus 745:
1.40 markus 746: /*
747: * If strict host key checking is in use, the user will have
748: * to edit the key manually and we can only abort.
749: */
1.108 markus 750: if (options.strict_host_key_checking) {
751: error("%s host key for %.200s has changed and you have "
752: "requested strict checking.", type, host);
753: goto fail;
754: }
1.38 markus 755:
1.40 markus 756: /*
757: * If strict host key checking has not been requested, allow
758: * the connection but without password authentication or
759: * agent forwarding.
760: */
1.38 markus 761: if (options.password_authentication) {
1.108 markus 762: error("Password authentication is disabled to avoid "
763: "man-in-the-middle attacks.");
1.38 markus 764: options.password_authentication = 0;
765: }
766: if (options.forward_agent) {
1.108 markus 767: error("Agent forwarding is disabled to avoid "
768: "man-in-the-middle attacks.");
1.38 markus 769: options.forward_agent = 0;
1.83 markus 770: }
771: if (options.forward_x11) {
1.108 markus 772: error("X11 forwarding is disabled to avoid "
773: "man-in-the-middle attacks.");
1.83 markus 774: options.forward_x11 = 0;
775: }
1.108 markus 776: if (options.num_local_forwards > 0 ||
777: options.num_remote_forwards > 0) {
778: error("Port forwarding is disabled to avoid "
779: "man-in-the-middle attacks.");
780: options.num_local_forwards =
781: options.num_remote_forwards = 0;
1.38 markus 782: }
1.40 markus 783: /*
784: * XXX Should permit the user to change to use the new id.
785: * This could be done by converting the host key to an
786: * identifying sentence, tell that the host identifies itself
787: * by that sentence, and ask the user if he/she whishes to
788: * accept the authentication.
789: */
1.38 markus 790: break;
1.88 markus 791: }
792:
793: if (options.check_host_ip && host_status != HOST_CHANGED &&
794: ip_status == HOST_CHANGED) {
795: log("Warning: the %s host key for '%.200s' "
1.94 itojun 796: "differs from the key for the IP address '%.128s'",
1.88 markus 797: type, host, ip);
798: if (host_status == HOST_OK)
799: log("Matching host key in %s:%d", host_file, host_line);
800: log("Offending key for IP in %s:%d", ip_file, ip_line);
801: if (options.strict_host_key_checking == 1) {
1.108 markus 802: error("Exiting, you have requested strict checking.");
803: goto fail;
1.88 markus 804: } else if (options.strict_host_key_checking == 2) {
1.112 markus 805: if (!confirm("Are you sure you want "
806: "to continue connecting (yes/no)? ")) {
1.108 markus 807: goto fail;
808: }
1.88 markus 809: }
1.38 markus 810: }
1.82 provos 811:
812: xfree(ip);
1.108 markus 813: return 0;
814:
815: fail:
816: xfree(ip);
817: return -1;
818: }
819:
820: int
821: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
822: {
823: struct stat st;
824:
825: /* return ok if the key can be found in an old keyfile */
826: if (stat(options.system_hostfile2, &st) == 0 ||
827: stat(options.user_hostfile2, &st) == 0) {
828: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
829: options.user_hostfile2, options.system_hostfile2) == 0)
830: return 0;
831: }
832: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
833: options.user_hostfile, options.system_hostfile);
1.51 markus 834: }
1.70 markus 835:
1.51 markus 836: /*
837: * Starts a dialog with the server, and authenticates the current user on the
838: * server. This does not need any extra privileges. The basic connection
839: * to the server must already have been established before this is called.
840: * If login fails, this function prints an error and never returns.
841: * This function does not require super-user privileges.
842: */
843: void
1.104 markus 844: ssh_login(Key **keys, int nkeys, const char *orighost,
1.103 markus 845: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 846: {
847: char *host, *cp;
1.70 markus 848: char *server_user, *local_user;
849:
850: local_user = xstrdup(pw->pw_name);
851: server_user = options.user ? options.user : local_user;
1.51 markus 852:
853: /* Convert the user-supplied hostname into all lowercase. */
854: host = xstrdup(orighost);
855: for (cp = host; *cp; cp++)
856: if (isupper(*cp))
857: *cp = tolower(*cp);
858:
859: /* Exchange protocol version identification strings with the server. */
860: ssh_exchange_identification();
861:
862: /* Put the connection into non-blocking mode. */
863: packet_set_nonblocking();
864:
865: /* key exchange */
866: /* authenticate user */
1.59 markus 867: if (compat20) {
868: ssh_kex2(host, hostaddr);
1.104 markus 869: ssh_userauth2(local_user, server_user, host, keys, nkeys);
1.59 markus 870: } else {
871: ssh_kex(host, hostaddr);
1.104 markus 872: ssh_userauth1(local_user, server_user, host, keys, nkeys);
1.59 markus 873: }
1.97 markus 874: }
875:
876: void
877: ssh_put_password(char *password)
878: {
879: int size;
880: char *padded;
881:
1.99 deraadt 882: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 883: packet_put_cstring(password);
1.99 deraadt 884: return;
885: }
1.97 markus 886: size = roundup(strlen(password) + 1, 32);
887: padded = xmalloc(size);
888: memset(padded, 0, size);
889: strlcpy(padded, password, size);
890: packet_put_string(padded, size);
891: memset(padded, 0, size);
892: xfree(padded);
1.1 deraadt 893: }
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