Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.78
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"
1.78 ! deraadt 16: RCSID("$OpenBSD: sshconnect.c,v 1.77 2000/08/28 03:50:54 deraadt Exp $");
1.1 deraadt 17:
1.66 markus 18: #include <openssl/bn.h>
1.71 markus 19: #include <openssl/dsa.h>
20: #include <openssl/rsa.h>
21:
1.1 deraadt 22: #include "xmalloc.h"
23: #include "rsa.h"
24: #include "ssh.h"
1.59 markus 25: #include "buffer.h"
1.1 deraadt 26: #include "packet.h"
27: #include "uidswap.h"
1.21 markus 28: #include "compat.h"
1.27 markus 29: #include "readconf.h"
1.58 markus 30: #include "key.h"
1.71 markus 31: #include "sshconnect.h"
1.58 markus 32: #include "hostfile.h"
1.51 markus 33:
1.70 markus 34: char *client_version_string = NULL;
35: char *server_version_string = NULL;
1.59 markus 36:
1.43 markus 37: extern Options options;
1.50 markus 38: extern char *__progname;
1.43 markus 39:
1.39 deraadt 40: /*
41: * Connect to the given ssh server using a proxy command.
42: */
1.3 provos 43: int
1.41 markus 44: ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid,
1.3 provos 45: const char *proxy_command)
1.1 deraadt 46: {
1.38 markus 47: Buffer command;
48: const char *cp;
49: char *command_string;
50: int pin[2], pout[2];
1.69 deraadt 51: pid_t pid;
1.49 markus 52: char strport[NI_MAXSERV];
1.38 markus 53:
54: /* Convert the port number into a string. */
1.49 markus 55: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 56:
57: /* Build the final command string in the buffer by making the
58: appropriate substitutions to the given proxy command. */
59: buffer_init(&command);
60: for (cp = proxy_command; *cp; cp++) {
61: if (cp[0] == '%' && cp[1] == '%') {
62: buffer_append(&command, "%", 1);
63: cp++;
64: continue;
65: }
66: if (cp[0] == '%' && cp[1] == 'h') {
67: buffer_append(&command, host, strlen(host));
68: cp++;
69: continue;
70: }
71: if (cp[0] == '%' && cp[1] == 'p') {
1.49 markus 72: buffer_append(&command, strport, strlen(strport));
1.38 markus 73: cp++;
74: continue;
75: }
76: buffer_append(&command, cp, 1);
77: }
78: buffer_append(&command, "\0", 1);
79:
80: /* Get the final command string. */
81: command_string = buffer_ptr(&command);
82:
83: /* Create pipes for communicating with the proxy. */
84: if (pipe(pin) < 0 || pipe(pout) < 0)
85: fatal("Could not create pipes to communicate with the proxy: %.100s",
86: strerror(errno));
87:
88: debug("Executing proxy command: %.500s", command_string);
89:
90: /* Fork and execute the proxy command. */
91: if ((pid = fork()) == 0) {
92: char *argv[10];
93:
94: /* Child. Permanently give up superuser privileges. */
95: permanently_set_uid(original_real_uid);
96:
97: /* Redirect stdin and stdout. */
98: close(pin[1]);
99: if (pin[0] != 0) {
100: if (dup2(pin[0], 0) < 0)
101: perror("dup2 stdin");
102: close(pin[0]);
103: }
104: close(pout[0]);
105: if (dup2(pout[1], 1) < 0)
106: perror("dup2 stdout");
107: /* Cannot be 1 because pin allocated two descriptors. */
108: close(pout[1]);
109:
110: /* Stderr is left as it is so that error messages get
111: printed on the user's terminal. */
112: argv[0] = "/bin/sh";
113: argv[1] = "-c";
114: argv[2] = command_string;
115: argv[3] = NULL;
116:
117: /* Execute the proxy command. Note that we gave up any
118: extra privileges above. */
119: execv("/bin/sh", argv);
120: perror("/bin/sh");
121: exit(1);
122: }
123: /* Parent. */
124: if (pid < 0)
125: fatal("fork failed: %.100s", strerror(errno));
126:
127: /* Close child side of the descriptors. */
128: close(pin[0]);
129: close(pout[1]);
130:
131: /* Free the command name. */
132: buffer_free(&command);
133:
134: /* Set the connection file descriptors. */
135: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 136:
1.38 markus 137: return 1;
1.1 deraadt 138: }
139:
1.39 deraadt 140: /*
141: * Creates a (possibly privileged) socket for use as the ssh connection.
142: */
1.38 markus 143: int
1.49 markus 144: ssh_create_socket(uid_t original_real_uid, int privileged, int family)
1.1 deraadt 145: {
1.38 markus 146: int sock;
1.1 deraadt 147:
1.40 markus 148: /*
149: * If we are running as root and want to connect to a privileged
150: * port, bind our own socket to a privileged port.
151: */
1.38 markus 152: if (privileged) {
153: int p = IPPORT_RESERVED - 1;
1.49 markus 154: sock = rresvport_af(&p, family);
1.38 markus 155: if (sock < 0)
1.55 markus 156: error("rresvport: af=%d %.100s", family, strerror(errno));
157: else
158: debug("Allocated local port %d.", p);
1.38 markus 159: } else {
1.46 markus 160: /*
161: * Just create an ordinary socket on arbitrary port. We use
162: * the user's uid to create the socket.
163: */
1.38 markus 164: temporarily_use_uid(original_real_uid);
1.49 markus 165: sock = socket(family, SOCK_STREAM, 0);
1.38 markus 166: if (sock < 0)
1.49 markus 167: error("socket: %.100s", strerror(errno));
1.38 markus 168: restore_uid();
169: }
170: return sock;
1.1 deraadt 171: }
172:
1.39 deraadt 173: /*
1.49 markus 174: * Opens a TCP/IP connection to the remote server on the given host.
175: * The address of the remote host will be returned in hostaddr.
176: * If port is 0, the default port will be used. If anonymous is zero,
1.39 deraadt 177: * a privileged port will be allocated to make the connection.
178: * This requires super-user privileges if anonymous is false.
179: * Connection_attempts specifies the maximum number of tries (one per
180: * second). If proxy_command is non-NULL, it specifies the command (with %h
181: * and %p substituted for host and port, respectively) to use to contact
182: * the daemon.
183: */
1.38 markus 184: int
1.49 markus 185: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.41 markus 186: u_short port, int connection_attempts,
1.38 markus 187: int anonymous, uid_t original_real_uid,
188: const char *proxy_command)
1.1 deraadt 189: {
1.49 markus 190: int sock = -1, attempt;
1.38 markus 191: struct servent *sp;
1.49 markus 192: struct addrinfo hints, *ai, *aitop;
193: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
194: int gaierr;
1.38 markus 195: struct linger linger;
196:
1.77 deraadt 197: debug("ssh_connect: getuid %u geteuid %u anon %d",
198: (u_int) getuid(), (u_int) geteuid(), anonymous);
1.38 markus 199:
200: /* Get default port if port has not been set. */
201: if (port == 0) {
202: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
203: if (sp)
204: port = ntohs(sp->s_port);
205: else
206: port = SSH_DEFAULT_PORT;
207: }
208: /* If a proxy command is given, connect using it. */
209: if (proxy_command != NULL)
210: return ssh_proxy_connect(host, port, original_real_uid, proxy_command);
211:
212: /* No proxy command. */
213:
1.49 markus 214: memset(&hints, 0, sizeof(hints));
215: hints.ai_family = IPv4or6;
216: hints.ai_socktype = SOCK_STREAM;
217: snprintf(strport, sizeof strport, "%d", port);
218: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 219: fatal("%s: %.100s: %s", __progname, host,
220: gai_strerror(gaierr));
1.38 markus 221:
1.46 markus 222: /*
223: * Try to connect several times. On some machines, the first time
224: * will sometimes fail. In general socket code appears to behave
225: * quite magically on many machines.
226: */
1.38 markus 227: for (attempt = 0; attempt < connection_attempts; attempt++) {
228: if (attempt > 0)
229: debug("Trying again...");
230:
1.49 markus 231: /* Loop through addresses for this host, and try each one in
1.68 markus 232: sequence until the connection succeeds. */
1.49 markus 233: for (ai = aitop; ai; ai = ai->ai_next) {
234: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
235: continue;
236: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
237: ntop, sizeof(ntop), strport, sizeof(strport),
238: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
239: error("ssh_connect: getnameinfo failed");
240: continue;
241: }
242: debug("Connecting to %.200s [%.100s] port %s.",
243: host, ntop, strport);
244:
245: /* Create a socket for connecting. */
1.68 markus 246: sock = ssh_create_socket(original_real_uid,
1.49 markus 247: !anonymous && geteuid() == 0 && port < IPPORT_RESERVED,
248: ai->ai_family);
249: if (sock < 0)
250: continue;
251:
252: /* Connect to the host. We use the user's uid in the
253: * hope that it will help with tcp_wrappers showing
254: * the remote uid as root.
1.40 markus 255: */
1.38 markus 256: temporarily_use_uid(original_real_uid);
1.49 markus 257: if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
258: /* Successful connection. */
1.74 markus 259: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 260: restore_uid();
261: break;
1.49 markus 262: } else {
1.38 markus 263: debug("connect: %.100s", strerror(errno));
264: restore_uid();
1.40 markus 265: /*
266: * Close the failed socket; there appear to
267: * be some problems when reusing a socket for
268: * which connect() has already returned an
269: * error.
270: */
1.38 markus 271: shutdown(sock, SHUT_RDWR);
272: close(sock);
273: }
274: }
1.49 markus 275: if (ai)
276: break; /* Successful connection. */
1.1 deraadt 277:
1.38 markus 278: /* Sleep a moment before retrying. */
279: sleep(1);
280: }
1.49 markus 281:
282: freeaddrinfo(aitop);
283:
1.38 markus 284: /* Return failure if we didn't get a successful connection. */
285: if (attempt >= connection_attempts)
286: return 0;
287:
288: debug("Connection established.");
289:
1.40 markus 290: /*
291: * Set socket options. We would like the socket to disappear as soon
292: * as it has been closed for whatever reason.
293: */
294: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.38 markus 295: linger.l_onoff = 1;
296: linger.l_linger = 5;
297: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
298:
299: /* Set the connection. */
300: packet_set_connection(sock, sock);
1.1 deraadt 301:
1.38 markus 302: return 1;
1.59 markus 303: }
304:
1.43 markus 305: /*
1.39 deraadt 306: * Waits for the server identification string, and sends our own
307: * identification string.
308: */
1.38 markus 309: void
310: ssh_exchange_identification()
1.1 deraadt 311: {
1.38 markus 312: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 313: int remote_major, remote_minor, i, mismatch;
1.38 markus 314: int connection_in = packet_get_connection_in();
315: int connection_out = packet_get_connection_out();
316:
317: /* Read other side\'s version identification. */
1.75 markus 318: for (;;) {
319: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 320: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 321: if (len < 0)
322: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
323: if (len != 1)
324: fatal("ssh_exchange_identification: Connection closed by remote host");
325: if (buf[i] == '\r') {
326: buf[i] = '\n';
327: buf[i + 1] = 0;
328: continue; /**XXX wait for \n */
329: }
330: if (buf[i] == '\n') {
331: buf[i + 1] = 0;
332: break;
333: }
1.38 markus 334: }
1.75 markus 335: buf[sizeof(buf) - 1] = 0;
1.76 markus 336: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 337: break;
1.75 markus 338: debug("ssh_exchange_identification: %s", buf);
1.38 markus 339: }
1.59 markus 340: server_version_string = xstrdup(buf);
1.38 markus 341:
1.40 markus 342: /*
343: * Check that the versions match. In future this might accept
344: * several versions and set appropriate flags to handle them.
345: */
1.59 markus 346: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
347: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 348: fatal("Bad remote protocol version identification: '%.100s'", buf);
349: debug("Remote protocol version %d.%d, remote software version %.100s",
350: remote_major, remote_minor, remote_version);
351:
1.59 markus 352: compat_datafellows(remote_version);
1.64 markus 353: mismatch = 0;
1.59 markus 354:
1.64 markus 355: switch(remote_major) {
356: case 1:
357: if (remote_minor == 99 &&
358: (options.protocol & SSH_PROTO_2) &&
359: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
360: enable_compat20();
361: break;
362: }
363: if (!(options.protocol & SSH_PROTO_1)) {
364: mismatch = 1;
365: break;
366: }
367: if (remote_minor < 3) {
368: fatal("Remote machine has too old SSH software version.");
369: } else if (remote_minor == 3) {
370: /* We speak 1.3, too. */
371: enable_compat13();
372: if (options.forward_agent) {
373: log("Agent forwarding disabled for protocol 1.3");
374: options.forward_agent = 0;
375: }
376: }
377: break;
378: case 2:
379: if (options.protocol & SSH_PROTO_2) {
380: enable_compat20();
381: break;
1.38 markus 382: }
1.64 markus 383: /* FALLTHROUGH */
1.68 markus 384: default:
1.64 markus 385: mismatch = 1;
386: break;
1.38 markus 387: }
1.64 markus 388: if (mismatch)
1.38 markus 389: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 390: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
391: remote_major);
1.70 markus 392: if (compat20)
393: packet_set_ssh2_format();
1.38 markus 394: /* Send our own protocol version identification. */
395: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 396: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.65 markus 397: compat20 ? PROTOCOL_MINOR_2 : PROTOCOL_MINOR_1,
1.59 markus 398: SSH_VERSION);
1.45 deraadt 399: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 400: fatal("write: %.100s", strerror(errno));
1.59 markus 401: client_version_string = xstrdup(buf);
402: chop(client_version_string);
403: chop(server_version_string);
404: debug("Local version string %.100s", client_version_string);
1.1 deraadt 405: }
406:
1.38 markus 407: int
408: read_yes_or_no(const char *prompt, int defval)
1.1 deraadt 409: {
1.38 markus 410: char buf[1024];
411: FILE *f;
412: int retval = -1;
413:
414: if (isatty(0))
415: f = stdin;
416: else
417: f = fopen("/dev/tty", "rw");
418:
419: if (f == NULL)
420: return 0;
421:
422: fflush(stdout);
423:
424: while (1) {
425: fprintf(stderr, "%s", prompt);
426: if (fgets(buf, sizeof(buf), f) == NULL) {
427: /* Print a newline (the prompt probably didn\'t have one). */
428: fprintf(stderr, "\n");
429: strlcpy(buf, "no", sizeof buf);
430: }
431: /* Remove newline from response. */
432: if (strchr(buf, '\n'))
433: *strchr(buf, '\n') = 0;
434:
435: if (buf[0] == 0)
436: retval = defval;
437: if (strcmp(buf, "yes") == 0)
438: retval = 1;
439: if (strcmp(buf, "no") == 0)
440: retval = 0;
441:
442: if (retval != -1) {
443: if (f != stdin)
444: fclose(f);
445: return retval;
446: }
1.1 deraadt 447: }
448: }
449:
1.39 deraadt 450: /*
1.46 markus 451: * check whether the supplied host key is valid, return only if ok.
1.39 deraadt 452: */
1.46 markus 453:
1.38 markus 454: void
1.70 markus 455: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
456: const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 457: {
1.58 markus 458: Key *file_key;
1.72 markus 459: char *type = key_type(host_key);
1.46 markus 460: char *ip = NULL;
1.38 markus 461: char hostline[1000], *hostp;
462: HostStatus host_status;
463: HostStatus ip_status;
1.49 markus 464: int local = 0, host_ip_differ = 0;
465: char ntop[NI_MAXHOST];
466:
467: /*
468: * Force accepting of the host key for loopback/localhost. The
469: * problem is that if the home directory is NFS-mounted to multiple
470: * machines, localhost will refer to a different machine in each of
471: * them, and the user will get bogus HOST_CHANGED warnings. This
472: * essentially disables host authentication for localhost; however,
473: * this is probably not a real problem.
474: */
1.70 markus 475: /** hostaddr == 0! */
1.49 markus 476: switch (hostaddr->sa_family) {
477: case AF_INET:
478: local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
479: break;
480: case AF_INET6:
481: local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
482: break;
483: default:
484: local = 0;
485: break;
486: }
487: if (local) {
488: debug("Forcing accepting of host key for loopback/localhost.");
489: return;
490: }
1.42 markus 491:
492: /*
1.44 markus 493: * Turn off check_host_ip for proxy connects, since
1.42 markus 494: * we don't have the remote ip-address
495: */
496: if (options.proxy_command != NULL && options.check_host_ip)
497: options.check_host_ip = 0;
1.38 markus 498:
1.49 markus 499: if (options.check_host_ip) {
500: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
501: NULL, 0, NI_NUMERICHOST) != 0)
502: fatal("check_host_key: getnameinfo failed");
503: ip = xstrdup(ntop);
504: }
1.38 markus 505:
1.46 markus 506: /*
507: * Store the host key from the known host file in here so that we can
508: * compare it with the key for the IP address.
509: */
1.58 markus 510: file_key = key_new(host_key->type);
1.38 markus 511:
1.40 markus 512: /*
513: * Check if the host key is present in the user\'s list of known
514: * hosts or in the systemwide list.
515: */
1.70 markus 516: host_status = check_host_in_hostfile(user_hostfile, host, host_key, file_key);
1.38 markus 517: if (host_status == HOST_NEW)
1.70 markus 518: host_status = check_host_in_hostfile(system_hostfile, host, host_key, file_key);
1.40 markus 519: /*
520: * Also perform check for the ip address, skip the check if we are
521: * localhost or the hostname was an ip address to begin with
522: */
1.38 markus 523: if (options.check_host_ip && !local && strcmp(host, ip)) {
1.58 markus 524: Key *ip_key = key_new(host_key->type);
1.70 markus 525: ip_status = check_host_in_hostfile(user_hostfile, ip, host_key, ip_key);
1.38 markus 526:
527: if (ip_status == HOST_NEW)
1.70 markus 528: ip_status = check_host_in_hostfile(system_hostfile, ip, host_key, ip_key);
1.38 markus 529: if (host_status == HOST_CHANGED &&
1.58 markus 530: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 531: host_ip_differ = 1;
532:
1.58 markus 533: key_free(ip_key);
1.38 markus 534: } else
535: ip_status = host_status;
536:
1.58 markus 537: key_free(file_key);
1.38 markus 538:
539: switch (host_status) {
540: case HOST_OK:
541: /* The host is known and the key matches. */
1.72 markus 542: debug("Host '%.200s' is known and matches the %s host key.",
543: host, type);
1.38 markus 544: if (options.check_host_ip) {
545: if (ip_status == HOST_NEW) {
1.70 markus 546: if (!add_host_to_hostfile(user_hostfile, ip, host_key))
1.72 markus 547: log("Failed to add the %s host key for IP address '%.30s' to the list of known hosts (%.30s).",
548: type, ip, user_hostfile);
1.38 markus 549: else
1.72 markus 550: log("Warning: Permanently added the %s host key for IP address '%.30s' to the list of known hosts.",
551: type, ip);
1.38 markus 552: } else if (ip_status != HOST_OK)
1.72 markus 553: log("Warning: the %s host key for '%.200s' differs from the key for the IP address '%.30s'",
554: type, host, ip);
1.38 markus 555: }
556: break;
557: case HOST_NEW:
558: /* The host is new. */
559: if (options.strict_host_key_checking == 1) {
560: /* User has requested strict host key checking. We will not add the host key
561: automatically. The only alternative left is to abort. */
1.72 markus 562: fatal("No %s host key is known for %.200s and you have requested strict checking.", type, host);
1.38 markus 563: } else if (options.strict_host_key_checking == 2) {
564: /* The default */
565: char prompt[1024];
1.58 markus 566: char *fp = key_fingerprint(host_key);
1.38 markus 567: snprintf(prompt, sizeof(prompt),
1.45 deraadt 568: "The authenticity of host '%.200s' can't be established.\n"
1.72 markus 569: "%s key fingerprint is %s.\n"
1.45 deraadt 570: "Are you sure you want to continue connecting (yes/no)? ",
1.72 markus 571: host, type, fp);
1.38 markus 572: if (!read_yes_or_no(prompt, -1))
573: fatal("Aborted by user!\n");
574: }
575: if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) {
576: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
577: hostp = hostline;
578: } else
579: hostp = host;
580:
581: /* If not in strict mode, add the key automatically to the local known_hosts file. */
1.70 markus 582: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.38 markus 583: log("Failed to add the host to the list of known hosts (%.500s).",
1.70 markus 584: user_hostfile);
1.38 markus 585: else
1.72 markus 586: log("Warning: Permanently added '%.200s' (%s) to the list of known hosts.",
587: hostp, type);
1.38 markus 588: break;
589: case HOST_CHANGED:
590: if (options.check_host_ip && host_ip_differ) {
591: char *msg;
592: if (ip_status == HOST_NEW)
593: msg = "is unknown";
594: else if (ip_status == HOST_OK)
595: msg = "is unchanged";
596: else
597: msg = "has a different value";
598: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
599: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
600: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 601: error("The %s host key for %s has changed,", type, host);
1.38 markus 602: error("and the key for the according IP address %s", ip);
603: error("%s. This could either mean that", msg);
604: error("DNS SPOOFING is happening or the IP address for the host");
605: error("and its host key have changed at the same time");
606: }
607: /* The host key has changed. */
608: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 609: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 610: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
611: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
612: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 613: error("It is also possible that the %s host key has just been changed.", type);
1.38 markus 614: error("Please contact your system administrator.");
615: error("Add correct host key in %.100s to get rid of this message.",
1.70 markus 616: user_hostfile);
1.38 markus 617:
1.40 markus 618: /*
619: * If strict host key checking is in use, the user will have
620: * to edit the key manually and we can only abort.
621: */
1.38 markus 622: if (options.strict_host_key_checking)
1.72 markus 623: fatal("%s host key for %.200s has changed and you have requested strict checking.", type, host);
1.38 markus 624:
1.40 markus 625: /*
626: * If strict host key checking has not been requested, allow
627: * the connection but without password authentication or
628: * agent forwarding.
629: */
1.38 markus 630: if (options.password_authentication) {
631: error("Password authentication is disabled to avoid trojan horses.");
632: options.password_authentication = 0;
633: }
634: if (options.forward_agent) {
635: error("Agent forwarding is disabled to avoid trojan horses.");
636: options.forward_agent = 0;
637: }
1.40 markus 638: /*
639: * XXX Should permit the user to change to use the new id.
640: * This could be done by converting the host key to an
641: * identifying sentence, tell that the host identifies itself
642: * by that sentence, and ask the user if he/she whishes to
643: * accept the authentication.
644: */
1.38 markus 645: break;
646: }
647: if (options.check_host_ip)
648: xfree(ip);
1.51 markus 649: }
1.70 markus 650:
1.51 markus 651: /*
652: * Starts a dialog with the server, and authenticates the current user on the
653: * server. This does not need any extra privileges. The basic connection
654: * to the server must already have been established before this is called.
655: * If login fails, this function prints an error and never returns.
656: * This function does not require super-user privileges.
657: */
658: void
659: ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost,
660: struct sockaddr *hostaddr, uid_t original_real_uid)
661: {
1.70 markus 662: struct passwd *pw;
1.51 markus 663: char *host, *cp;
1.70 markus 664: char *server_user, *local_user;
665:
666: /* Get local user name. Use it as server user if no user name was given. */
667: pw = getpwuid(original_real_uid);
668: if (!pw)
1.77 deraadt 669: fatal("User id %u not found from user database.", original_real_uid);
1.70 markus 670: local_user = xstrdup(pw->pw_name);
671: server_user = options.user ? options.user : local_user;
1.51 markus 672:
673: /* Convert the user-supplied hostname into all lowercase. */
674: host = xstrdup(orighost);
675: for (cp = host; *cp; cp++)
676: if (isupper(*cp))
677: *cp = tolower(*cp);
678:
679: /* Exchange protocol version identification strings with the server. */
680: ssh_exchange_identification();
681:
682: /* Put the connection into non-blocking mode. */
683: packet_set_nonblocking();
684:
685: /* key exchange */
686: /* authenticate user */
1.59 markus 687: if (compat20) {
688: ssh_kex2(host, hostaddr);
1.70 markus 689: ssh_userauth2(server_user, host);
1.59 markus 690: } else {
691: ssh_kex(host, hostaddr);
1.70 markus 692: ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key);
1.59 markus 693: }
1.1 deraadt 694: }
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