Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.90
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"
1.90 ! markus 16: RCSID("$OpenBSD: sshconnect.c,v 1.89 2001/01/04 22:41:03 markus 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. */
1.89 markus 112: argv[0] = _PATH_BSHELL;
1.38 markus 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. */
1.89 markus 119: execv(argv[0], argv);
120: perror(argv[0]);
1.38 markus 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: {
1.90 ! markus 190: int gaierr;
! 191: int on = 1;
1.49 markus 192: int sock = -1, attempt;
1.90 ! markus 193: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 194: struct addrinfo hints, *ai, *aitop;
1.38 markus 195: struct linger linger;
1.90 ! markus 196: struct servent *sp;
1.38 markus 197:
1.77 deraadt 198: debug("ssh_connect: getuid %u geteuid %u anon %d",
199: (u_int) getuid(), (u_int) geteuid(), anonymous);
1.38 markus 200:
201: /* Get default port if port has not been set. */
202: if (port == 0) {
203: sp = getservbyname(SSH_SERVICE_NAME, "tcp");
204: if (sp)
205: port = ntohs(sp->s_port);
206: else
207: port = SSH_DEFAULT_PORT;
208: }
209: /* If a proxy command is given, connect using it. */
210: if (proxy_command != NULL)
211: return ssh_proxy_connect(host, port, original_real_uid, proxy_command);
212:
213: /* No proxy command. */
214:
1.49 markus 215: memset(&hints, 0, sizeof(hints));
216: hints.ai_family = IPv4or6;
217: hints.ai_socktype = SOCK_STREAM;
218: snprintf(strport, sizeof strport, "%d", port);
219: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 220: fatal("%s: %.100s: %s", __progname, host,
221: gai_strerror(gaierr));
1.38 markus 222:
1.46 markus 223: /*
224: * Try to connect several times. On some machines, the first time
225: * will sometimes fail. In general socket code appears to behave
226: * quite magically on many machines.
227: */
1.38 markus 228: for (attempt = 0; attempt < connection_attempts; attempt++) {
229: if (attempt > 0)
230: debug("Trying again...");
231:
1.49 markus 232: /* Loop through addresses for this host, and try each one in
1.68 markus 233: sequence until the connection succeeds. */
1.49 markus 234: for (ai = aitop; ai; ai = ai->ai_next) {
235: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
236: continue;
237: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
238: ntop, sizeof(ntop), strport, sizeof(strport),
239: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
240: error("ssh_connect: getnameinfo failed");
241: continue;
242: }
243: debug("Connecting to %.200s [%.100s] port %s.",
244: host, ntop, strport);
245:
246: /* Create a socket for connecting. */
1.68 markus 247: sock = ssh_create_socket(original_real_uid,
1.80 markus 248: !anonymous && geteuid() == 0,
1.49 markus 249: ai->ai_family);
250: if (sock < 0)
251: continue;
252:
253: /* Connect to the host. We use the user's uid in the
254: * hope that it will help with tcp_wrappers showing
255: * the remote uid as root.
1.40 markus 256: */
1.38 markus 257: temporarily_use_uid(original_real_uid);
1.49 markus 258: if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
259: /* Successful connection. */
1.74 markus 260: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 261: restore_uid();
262: break;
1.49 markus 263: } else {
1.38 markus 264: debug("connect: %.100s", strerror(errno));
265: restore_uid();
1.40 markus 266: /*
267: * Close the failed socket; there appear to
268: * be some problems when reusing a socket for
269: * which connect() has already returned an
270: * error.
271: */
1.38 markus 272: shutdown(sock, SHUT_RDWR);
273: close(sock);
274: }
275: }
1.49 markus 276: if (ai)
277: break; /* Successful connection. */
1.1 deraadt 278:
1.38 markus 279: /* Sleep a moment before retrying. */
280: sleep(1);
281: }
1.49 markus 282:
283: freeaddrinfo(aitop);
284:
1.38 markus 285: /* Return failure if we didn't get a successful connection. */
286: if (attempt >= connection_attempts)
287: return 0;
288:
289: debug("Connection established.");
290:
1.40 markus 291: /*
292: * Set socket options. We would like the socket to disappear as soon
293: * as it has been closed for whatever reason.
294: */
295: /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
1.38 markus 296: linger.l_onoff = 1;
297: linger.l_linger = 5;
1.90 ! markus 298: setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
! 299:
! 300: /* Set keepalives if requested. */
! 301: if (options.keepalives &&
! 302: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
! 303: sizeof(on)) < 0)
! 304: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 305:
306: /* Set the connection. */
307: packet_set_connection(sock, sock);
1.1 deraadt 308:
1.38 markus 309: return 1;
1.59 markus 310: }
311:
1.43 markus 312: /*
1.39 deraadt 313: * Waits for the server identification string, and sends our own
314: * identification string.
315: */
1.38 markus 316: void
317: ssh_exchange_identification()
1.1 deraadt 318: {
1.38 markus 319: char buf[256], remote_version[256]; /* must be same size! */
1.64 markus 320: int remote_major, remote_minor, i, mismatch;
1.38 markus 321: int connection_in = packet_get_connection_in();
322: int connection_out = packet_get_connection_out();
1.81 markus 323: int minor1 = PROTOCOL_MINOR_1;
1.38 markus 324:
325: /* Read other side\'s version identification. */
1.75 markus 326: for (;;) {
327: for (i = 0; i < sizeof(buf) - 1; i++) {
1.76 markus 328: int len = atomicio(read, connection_in, &buf[i], 1);
1.75 markus 329: if (len < 0)
330: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
331: if (len != 1)
332: fatal("ssh_exchange_identification: Connection closed by remote host");
333: if (buf[i] == '\r') {
334: buf[i] = '\n';
335: buf[i + 1] = 0;
336: continue; /**XXX wait for \n */
337: }
338: if (buf[i] == '\n') {
339: buf[i + 1] = 0;
340: break;
341: }
1.38 markus 342: }
1.75 markus 343: buf[sizeof(buf) - 1] = 0;
1.76 markus 344: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 345: break;
1.75 markus 346: debug("ssh_exchange_identification: %s", buf);
1.38 markus 347: }
1.59 markus 348: server_version_string = xstrdup(buf);
1.38 markus 349:
1.40 markus 350: /*
351: * Check that the versions match. In future this might accept
352: * several versions and set appropriate flags to handle them.
353: */
1.59 markus 354: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
355: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 356: fatal("Bad remote protocol version identification: '%.100s'", buf);
357: debug("Remote protocol version %d.%d, remote software version %.100s",
358: remote_major, remote_minor, remote_version);
359:
1.59 markus 360: compat_datafellows(remote_version);
1.64 markus 361: mismatch = 0;
1.59 markus 362:
1.64 markus 363: switch(remote_major) {
364: case 1:
365: if (remote_minor == 99 &&
366: (options.protocol & SSH_PROTO_2) &&
367: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
368: enable_compat20();
369: break;
370: }
371: if (!(options.protocol & SSH_PROTO_1)) {
372: mismatch = 1;
373: break;
374: }
375: if (remote_minor < 3) {
376: fatal("Remote machine has too old SSH software version.");
1.81 markus 377: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 378: /* We speak 1.3, too. */
379: enable_compat13();
1.81 markus 380: minor1 = 3;
1.64 markus 381: if (options.forward_agent) {
382: log("Agent forwarding disabled for protocol 1.3");
383: options.forward_agent = 0;
384: }
385: }
386: break;
387: case 2:
388: if (options.protocol & SSH_PROTO_2) {
389: enable_compat20();
390: break;
1.38 markus 391: }
1.64 markus 392: /* FALLTHROUGH */
1.68 markus 393: default:
1.64 markus 394: mismatch = 1;
395: break;
1.38 markus 396: }
1.64 markus 397: if (mismatch)
1.38 markus 398: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 399: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
400: remote_major);
1.70 markus 401: if (compat20)
402: packet_set_ssh2_format();
1.38 markus 403: /* Send our own protocol version identification. */
404: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 405: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 406: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 407: SSH_VERSION);
1.45 deraadt 408: if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 409: fatal("write: %.100s", strerror(errno));
1.59 markus 410: client_version_string = xstrdup(buf);
411: chop(client_version_string);
412: chop(server_version_string);
413: debug("Local version string %.100s", client_version_string);
1.1 deraadt 414: }
415:
1.38 markus 416: int
417: read_yes_or_no(const char *prompt, int defval)
1.1 deraadt 418: {
1.38 markus 419: char buf[1024];
420: FILE *f;
421: int retval = -1;
422:
1.88 markus 423: if (isatty(STDIN_FILENO))
1.38 markus 424: f = stdin;
425: else
426: f = fopen("/dev/tty", "rw");
427:
428: if (f == NULL)
429: return 0;
430:
431: fflush(stdout);
432:
433: while (1) {
434: fprintf(stderr, "%s", prompt);
435: if (fgets(buf, sizeof(buf), f) == NULL) {
436: /* Print a newline (the prompt probably didn\'t have one). */
437: fprintf(stderr, "\n");
438: strlcpy(buf, "no", sizeof buf);
439: }
440: /* Remove newline from response. */
441: if (strchr(buf, '\n'))
442: *strchr(buf, '\n') = 0;
443:
444: if (buf[0] == 0)
445: retval = defval;
446: if (strcmp(buf, "yes") == 0)
447: retval = 1;
1.79 markus 448: else if (strcmp(buf, "no") == 0)
1.38 markus 449: retval = 0;
1.79 markus 450: else
451: fprintf(stderr, "Please type 'yes' or 'no'.\n");
1.38 markus 452:
453: if (retval != -1) {
454: if (f != stdin)
455: fclose(f);
456: return retval;
457: }
1.1 deraadt 458: }
459: }
460:
1.39 deraadt 461: /*
1.46 markus 462: * check whether the supplied host key is valid, return only if ok.
1.39 deraadt 463: */
1.46 markus 464:
1.38 markus 465: void
1.70 markus 466: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
467: const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 468: {
1.58 markus 469: Key *file_key;
1.72 markus 470: char *type = key_type(host_key);
1.46 markus 471: char *ip = NULL;
1.38 markus 472: char hostline[1000], *hostp;
473: HostStatus host_status;
474: HostStatus ip_status;
1.49 markus 475: int local = 0, host_ip_differ = 0;
476: char ntop[NI_MAXHOST];
1.88 markus 477: int host_line, ip_line;
1.85 markus 478: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 479:
480: /*
481: * Force accepting of the host key for loopback/localhost. The
482: * problem is that if the home directory is NFS-mounted to multiple
483: * machines, localhost will refer to a different machine in each of
484: * them, and the user will get bogus HOST_CHANGED warnings. This
485: * essentially disables host authentication for localhost; however,
486: * this is probably not a real problem.
487: */
1.70 markus 488: /** hostaddr == 0! */
1.49 markus 489: switch (hostaddr->sa_family) {
490: case AF_INET:
491: local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
492: break;
493: case AF_INET6:
494: local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
495: break;
496: default:
497: local = 0;
498: break;
499: }
1.88 markus 500: if (local && options.host_key_alias == NULL) {
501: debug("Forcing accepting of host key for "
502: "loopback/localhost.");
503: return;
1.49 markus 504: }
1.42 markus 505:
506: /*
1.88 markus 507: * We don't have the remote ip-address for connections
508: * using a proxy command
1.42 markus 509: */
1.84 markus 510: if (options.proxy_command == NULL) {
511: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 512: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 513: fatal("check_host_key: getnameinfo failed");
514: ip = xstrdup(ntop);
515: } else {
516: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 517: }
1.88 markus 518: /*
519: * Turn off check_host_ip if the connection is to localhost, via proxy
520: * command or if we don't have a hostname to compare with
521: */
522: if (options.check_host_ip &&
523: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
524: options.check_host_ip = 0;
1.86 markus 525:
526: /*
527: * Allow the user to record the key under a different name. This is
528: * useful for ssh tunneling over forwarded connections or if you run
529: * multiple sshd's on different ports on the same machine.
530: */
531: if (options.host_key_alias != NULL) {
532: host = options.host_key_alias;
533: debug("using hostkeyalias: %s", host);
1.84 markus 534: }
1.38 markus 535:
1.46 markus 536: /*
537: * Store the host key from the known host file in here so that we can
538: * compare it with the key for the IP address.
539: */
1.58 markus 540: file_key = key_new(host_key->type);
1.38 markus 541:
1.40 markus 542: /*
543: * Check if the host key is present in the user\'s list of known
544: * hosts or in the systemwide list.
545: */
1.85 markus 546: host_file = user_hostfile;
547: host_status = check_host_in_hostfile(host_file, host, host_key, file_key, &host_line);
548: if (host_status == HOST_NEW) {
549: host_file = system_hostfile;
550: host_status = check_host_in_hostfile(host_file, host, host_key, file_key, &host_line);
551: }
1.40 markus 552: /*
553: * Also perform check for the ip address, skip the check if we are
554: * localhost or the hostname was an ip address to begin with
555: */
1.88 markus 556: if (options.check_host_ip) {
1.58 markus 557: Key *ip_key = key_new(host_key->type);
1.38 markus 558:
1.85 markus 559: ip_file = user_hostfile;
560: ip_status = check_host_in_hostfile(ip_file, ip, host_key, ip_key, &ip_line);
561: if (ip_status == HOST_NEW) {
562: ip_file = system_hostfile;
563: ip_status = check_host_in_hostfile(ip_file, ip, host_key, ip_key, &ip_line);
564: }
1.38 markus 565: if (host_status == HOST_CHANGED &&
1.58 markus 566: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 567: host_ip_differ = 1;
568:
1.58 markus 569: key_free(ip_key);
1.38 markus 570: } else
571: ip_status = host_status;
572:
1.58 markus 573: key_free(file_key);
1.38 markus 574:
575: switch (host_status) {
576: case HOST_OK:
577: /* The host is known and the key matches. */
1.72 markus 578: debug("Host '%.200s' is known and matches the %s host key.",
579: host, type);
1.85 markus 580: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 581: if (options.check_host_ip && ip_status == HOST_NEW) {
582: if (!add_host_to_hostfile(user_hostfile, ip, host_key))
583: log("Failed to add the %s host key for IP address '%.30s' to the list of known hosts (%.30s).",
584: type, ip, user_hostfile);
585: else
586: log("Warning: Permanently added the %s host key for IP address '%.30s' to the list of known hosts.",
587: type, ip);
1.38 markus 588: }
589: break;
590: case HOST_NEW:
591: /* The host is new. */
592: if (options.strict_host_key_checking == 1) {
593: /* User has requested strict host key checking. We will not add the host key
594: automatically. The only alternative left is to abort. */
1.72 markus 595: fatal("No %s host key is known for %.200s and you have requested strict checking.", type, host);
1.38 markus 596: } else if (options.strict_host_key_checking == 2) {
597: /* The default */
598: char prompt[1024];
599: snprintf(prompt, sizeof(prompt),
1.82 provos 600: "The authenticity of host '%.200s (%s)' can't be established.\n"
1.72 markus 601: "%s key fingerprint is %s.\n"
1.45 deraadt 602: "Are you sure you want to continue connecting (yes/no)? ",
1.87 markus 603: host, ip, type, key_fingerprint(host_key));
1.38 markus 604: if (!read_yes_or_no(prompt, -1))
605: fatal("Aborted by user!\n");
606: }
1.88 markus 607: if (options.check_host_ip && ip_status == HOST_NEW) {
1.38 markus 608: snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
609: hostp = hostline;
610: } else
611: hostp = host;
612:
613: /* If not in strict mode, add the key automatically to the local known_hosts file. */
1.70 markus 614: if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
1.38 markus 615: log("Failed to add the host to the list of known hosts (%.500s).",
1.70 markus 616: user_hostfile);
1.38 markus 617: else
1.72 markus 618: log("Warning: Permanently added '%.200s' (%s) to the list of known hosts.",
619: hostp, type);
1.38 markus 620: break;
621: case HOST_CHANGED:
622: if (options.check_host_ip && host_ip_differ) {
623: char *msg;
624: if (ip_status == HOST_NEW)
625: msg = "is unknown";
626: else if (ip_status == HOST_OK)
627: msg = "is unchanged";
628: else
629: msg = "has a different value";
630: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
631: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
632: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 633: error("The %s host key for %s has changed,", type, host);
1.38 markus 634: error("and the key for the according IP address %s", ip);
635: error("%s. This could either mean that", msg);
636: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 637: error("and its host key have changed at the same time.");
1.88 markus 638: if (ip_status != HOST_NEW)
1.85 markus 639: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 640: }
641: /* The host key has changed. */
642: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.47 markus 643: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1.38 markus 644: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
645: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
646: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1.72 markus 647: error("It is also possible that the %s host key has just been changed.", type);
1.87 markus 648: error("The fingerprint for the %s key sent by the remote host is\n%s.",
649: type, key_fingerprint(host_key));
1.38 markus 650: error("Please contact your system administrator.");
651: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 652: user_hostfile);
1.85 markus 653: error("Offending key in %s:%d", host_file, host_line);
1.38 markus 654:
1.40 markus 655: /*
656: * If strict host key checking is in use, the user will have
657: * to edit the key manually and we can only abort.
658: */
1.38 markus 659: if (options.strict_host_key_checking)
1.72 markus 660: fatal("%s host key for %.200s has changed and you have requested strict checking.", type, host);
1.38 markus 661:
1.40 markus 662: /*
663: * If strict host key checking has not been requested, allow
664: * the connection but without password authentication or
665: * agent forwarding.
666: */
1.38 markus 667: if (options.password_authentication) {
668: error("Password authentication is disabled to avoid trojan horses.");
669: options.password_authentication = 0;
670: }
671: if (options.forward_agent) {
672: error("Agent forwarding is disabled to avoid trojan horses.");
673: options.forward_agent = 0;
1.83 markus 674: }
675: if (options.forward_x11) {
676: error("X11 forwarding is disabled to avoid trojan horses.");
677: options.forward_x11 = 0;
678: }
679: if (options.num_local_forwards > 0 || options.num_remote_forwards > 0) {
680: error("Port forwarding is disabled to avoid trojan horses.");
681: options.num_local_forwards = options.num_remote_forwards = 0;
1.38 markus 682: }
1.40 markus 683: /*
684: * XXX Should permit the user to change to use the new id.
685: * This could be done by converting the host key to an
686: * identifying sentence, tell that the host identifies itself
687: * by that sentence, and ask the user if he/she whishes to
688: * accept the authentication.
689: */
1.38 markus 690: break;
1.88 markus 691: }
692:
693: if (options.check_host_ip && host_status != HOST_CHANGED &&
694: ip_status == HOST_CHANGED) {
695: log("Warning: the %s host key for '%.200s' "
696: "differs from the key for the IP address '%.30s'",
697: type, host, ip);
698: if (host_status == HOST_OK)
699: log("Matching host key in %s:%d", host_file, host_line);
700: log("Offending key for IP in %s:%d", ip_file, ip_line);
701: if (options.strict_host_key_checking == 1) {
702: fatal("Exiting, you have requested strict checking.");
703: } else if (options.strict_host_key_checking == 2) {
704: if (!read_yes_or_no("Continue?", -1))
705: fatal("Aborted by user!\n");
706: }
1.38 markus 707: }
1.82 provos 708:
709: xfree(ip);
1.51 markus 710: }
1.70 markus 711:
1.51 markus 712: /*
713: * Starts a dialog with the server, and authenticates the current user on the
714: * server. This does not need any extra privileges. The basic connection
715: * to the server must already have been established before this is called.
716: * If login fails, this function prints an error and never returns.
717: * This function does not require super-user privileges.
718: */
719: void
720: ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost,
721: struct sockaddr *hostaddr, uid_t original_real_uid)
722: {
1.70 markus 723: struct passwd *pw;
1.51 markus 724: char *host, *cp;
1.70 markus 725: char *server_user, *local_user;
726:
727: /* Get local user name. Use it as server user if no user name was given. */
728: pw = getpwuid(original_real_uid);
729: if (!pw)
1.77 deraadt 730: fatal("User id %u not found from user database.", original_real_uid);
1.70 markus 731: local_user = xstrdup(pw->pw_name);
732: server_user = options.user ? options.user : local_user;
1.51 markus 733:
734: /* Convert the user-supplied hostname into all lowercase. */
735: host = xstrdup(orighost);
736: for (cp = host; *cp; cp++)
737: if (isupper(*cp))
738: *cp = tolower(*cp);
739:
740: /* Exchange protocol version identification strings with the server. */
741: ssh_exchange_identification();
742:
743: /* Put the connection into non-blocking mode. */
744: packet_set_nonblocking();
745:
746: /* key exchange */
747: /* authenticate user */
1.59 markus 748: if (compat20) {
749: ssh_kex2(host, hostaddr);
1.70 markus 750: ssh_userauth2(server_user, host);
1.59 markus 751: } else {
752: ssh_kex(host, hostaddr);
1.70 markus 753: ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key);
1.59 markus 754: }
1.1 deraadt 755: }
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