Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.177
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"
1.174 stevesk 16:
17: #include <sys/types.h>
18: #include <sys/wait.h>
1.175 stevesk 19: #include <sys/stat.h>
1.172 stevesk 20:
1.176 stevesk 21: #include <ctype.h>
1.172 stevesk 22: #include <paths.h>
1.71 markus 23:
1.91 markus 24: #include "ssh.h"
1.1 deraadt 25: #include "xmalloc.h"
26: #include "rsa.h"
1.59 markus 27: #include "buffer.h"
1.1 deraadt 28: #include "packet.h"
29: #include "uidswap.h"
1.21 markus 30: #include "compat.h"
1.58 markus 31: #include "key.h"
1.71 markus 32: #include "sshconnect.h"
1.58 markus 33: #include "hostfile.h"
1.91 markus 34: #include "log.h"
35: #include "readconf.h"
36: #include "atomicio.h"
37: #include "misc.h"
1.140 jakob 38: #include "dns.h"
39:
1.70 markus 40: char *client_version_string = NULL;
41: char *server_version_string = NULL;
1.59 markus 42:
1.169 stevesk 43: static int matching_host_key_dns = 0;
1.145 jakob 44:
1.124 markus 45: /* import */
1.43 markus 46: extern Options options;
1.50 markus 47: extern char *__progname;
1.124 markus 48: extern uid_t original_real_uid;
49: extern uid_t original_effective_uid;
1.135 djm 50: extern pid_t proxy_command_pid;
1.91 markus 51:
1.132 markus 52: static int show_other_keys(const char *, Key *);
1.150 jakob 53: static void warn_changed_key(Key *);
1.132 markus 54:
1.39 deraadt 55: /*
56: * Connect to the given ssh server using a proxy command.
57: */
1.109 itojun 58: static int
1.124 markus 59: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 60: {
1.164 djm 61: char *command_string, *tmp;
1.38 markus 62: int pin[2], pout[2];
1.69 deraadt 63: pid_t pid;
1.49 markus 64: char strport[NI_MAXSERV];
1.164 djm 65: size_t len;
1.38 markus 66:
67: /* Convert the port number into a string. */
1.49 markus 68: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 69:
1.135 djm 70: /*
71: * Build the final command string in the buffer by making the
72: * appropriate substitutions to the given proxy command.
73: *
1.154 djm 74: * Use "exec" to avoid "sh -c" processes on some platforms
1.135 djm 75: * (e.g. Solaris)
76: */
1.164 djm 77: len = strlen(proxy_command) + 6;
78: tmp = xmalloc(len);
79: strlcpy(tmp, "exec ", len);
80: strlcat(tmp, proxy_command, len);
81: command_string = percent_expand(tmp, "h", host,
82: "p", strport, (char *)NULL);
83: xfree(tmp);
1.38 markus 84:
85: /* Create pipes for communicating with the proxy. */
86: if (pipe(pin) < 0 || pipe(pout) < 0)
87: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 88: strerror(errno));
1.38 markus 89:
90: debug("Executing proxy command: %.500s", command_string);
91:
92: /* Fork and execute the proxy command. */
93: if ((pid = fork()) == 0) {
94: char *argv[10];
95:
96: /* Child. Permanently give up superuser privileges. */
1.124 markus 97: seteuid(original_real_uid);
98: setuid(original_real_uid);
1.38 markus 99:
100: /* Redirect stdin and stdout. */
101: close(pin[1]);
102: if (pin[0] != 0) {
103: if (dup2(pin[0], 0) < 0)
104: perror("dup2 stdin");
105: close(pin[0]);
106: }
107: close(pout[0]);
108: if (dup2(pout[1], 1) < 0)
109: perror("dup2 stdout");
110: /* Cannot be 1 because pin allocated two descriptors. */
111: close(pout[1]);
112:
113: /* Stderr is left as it is so that error messages get
114: printed on the user's terminal. */
1.89 markus 115: argv[0] = _PATH_BSHELL;
1.38 markus 116: argv[1] = "-c";
117: argv[2] = command_string;
118: argv[3] = NULL;
119:
120: /* Execute the proxy command. Note that we gave up any
121: extra privileges above. */
1.89 markus 122: execv(argv[0], argv);
123: perror(argv[0]);
1.38 markus 124: exit(1);
125: }
126: /* Parent. */
127: if (pid < 0)
128: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 129: else
130: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 131:
132: /* Close child side of the descriptors. */
133: close(pin[0]);
134: close(pout[1]);
135:
136: /* Free the command name. */
1.164 djm 137: xfree(command_string);
1.38 markus 138:
139: /* Set the connection file descriptors. */
140: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 141:
1.110 markus 142: /* Indicate OK return */
143: return 0;
1.1 deraadt 144: }
145:
1.39 deraadt 146: /*
147: * Creates a (possibly privileged) socket for use as the ssh connection.
148: */
1.109 itojun 149: static int
1.139 markus 150: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 151: {
1.105 markus 152: int sock, gaierr;
153: struct addrinfo hints, *res;
1.1 deraadt 154:
1.40 markus 155: /*
156: * If we are running as root and want to connect to a privileged
157: * port, bind our own socket to a privileged port.
158: */
1.38 markus 159: if (privileged) {
160: int p = IPPORT_RESERVED - 1;
1.124 markus 161: PRIV_START;
1.139 markus 162: sock = rresvport_af(&p, ai->ai_family);
1.124 markus 163: PRIV_END;
1.38 markus 164: if (sock < 0)
1.139 markus 165: error("rresvport: af=%d %.100s", ai->ai_family,
166: strerror(errno));
1.55 markus 167: else
168: debug("Allocated local port %d.", p);
1.105 markus 169: return sock;
170: }
1.139 markus 171: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.105 markus 172: if (sock < 0)
173: error("socket: %.100s", strerror(errno));
174:
175: /* Bind the socket to an alternative local IP address */
176: if (options.bind_address == NULL)
177: return sock;
178:
179: memset(&hints, 0, sizeof(hints));
1.139 markus 180: hints.ai_family = ai->ai_family;
181: hints.ai_socktype = ai->ai_socktype;
182: hints.ai_protocol = ai->ai_protocol;
1.105 markus 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:
1.141 djm 201: static int
202: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
203: socklen_t addrlen, int timeout)
204: {
205: fd_set *fdset;
206: struct timeval tv;
207: socklen_t optlen;
1.142 djm 208: int fdsetsz, optval, rc, result = -1;
1.141 djm 209:
210: if (timeout <= 0)
211: return (connect(sockfd, serv_addr, addrlen));
212:
1.156 djm 213: set_nonblock(sockfd);
1.141 djm 214: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 215: if (rc == 0) {
216: unset_nonblock(sockfd);
1.141 djm 217: return (0);
1.156 djm 218: }
1.141 djm 219: if (errno != EINPROGRESS)
220: return (-1);
221:
222: fdsetsz = howmany(sockfd + 1, NFDBITS) * sizeof(fd_mask);
223: fdset = (fd_set *)xmalloc(fdsetsz);
224:
1.147 markus 225: memset(fdset, 0, fdsetsz);
1.141 djm 226: FD_SET(sockfd, fdset);
227: tv.tv_sec = timeout;
228: tv.tv_usec = 0;
229:
1.162 deraadt 230: for (;;) {
1.141 djm 231: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
232: if (rc != -1 || errno != EINTR)
233: break;
234: }
235:
1.162 deraadt 236: switch (rc) {
1.141 djm 237: case 0:
238: /* Timed out */
239: errno = ETIMEDOUT;
1.142 djm 240: break;
1.141 djm 241: case -1:
242: /* Select error */
1.154 djm 243: debug("select: %s", strerror(errno));
1.142 djm 244: break;
1.141 djm 245: case 1:
246: /* Completed or failed */
247: optval = 0;
248: optlen = sizeof(optval);
1.154 djm 249: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 250: &optlen) == -1) {
1.154 djm 251: debug("getsockopt: %s", strerror(errno));
1.142 djm 252: break;
1.148 markus 253: }
1.141 djm 254: if (optval != 0) {
255: errno = optval;
1.142 djm 256: break;
1.141 djm 257: }
1.142 djm 258: result = 0;
1.156 djm 259: unset_nonblock(sockfd);
1.141 djm 260: break;
261: default:
262: /* Should not occur */
263: fatal("Bogus return (%d) from select()", rc);
264: }
265:
1.142 djm 266: xfree(fdset);
267: return (result);
1.141 djm 268: }
269:
1.39 deraadt 270: /*
1.49 markus 271: * Opens a TCP/IP connection to the remote server on the given host.
272: * The address of the remote host will be returned in hostaddr.
1.124 markus 273: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 274: * a privileged port will be allocated to make the connection.
1.124 markus 275: * This requires super-user privileges if needpriv is true.
1.39 deraadt 276: * Connection_attempts specifies the maximum number of tries (one per
277: * second). If proxy_command is non-NULL, it specifies the command (with %h
278: * and %p substituted for host and port, respectively) to use to contact
279: * the daemon.
280: */
1.38 markus 281: int
1.49 markus 282: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 283: u_short port, int family, int connection_attempts,
1.124 markus 284: int needpriv, const char *proxy_command)
1.1 deraadt 285: {
1.90 markus 286: int gaierr;
287: int on = 1;
1.49 markus 288: int sock = -1, attempt;
1.90 markus 289: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 290: struct addrinfo hints, *ai, *aitop;
1.38 markus 291:
1.136 markus 292: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 293:
294: /* If a proxy command is given, connect using it. */
295: if (proxy_command != NULL)
1.124 markus 296: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 297:
298: /* No proxy command. */
299:
1.49 markus 300: memset(&hints, 0, sizeof(hints));
1.115 markus 301: hints.ai_family = family;
1.49 markus 302: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 303: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 304: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 305: fatal("%s: %.100s: %s", __progname, host,
306: gai_strerror(gaierr));
1.38 markus 307:
1.46 markus 308: /*
309: * Try to connect several times. On some machines, the first time
310: * will sometimes fail. In general socket code appears to behave
311: * quite magically on many machines.
1.110 markus 312: */
313: for (attempt = 0; ;) {
1.38 markus 314: if (attempt > 0)
315: debug("Trying again...");
316:
1.49 markus 317: /* Loop through addresses for this host, and try each one in
1.68 markus 318: sequence until the connection succeeds. */
1.49 markus 319: for (ai = aitop; ai; ai = ai->ai_next) {
320: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
321: continue;
322: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
323: ntop, sizeof(ntop), strport, sizeof(strport),
324: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
325: error("ssh_connect: getnameinfo failed");
326: continue;
327: }
328: debug("Connecting to %.200s [%.100s] port %s.",
329: host, ntop, strport);
330:
331: /* Create a socket for connecting. */
1.139 markus 332: sock = ssh_create_socket(needpriv, ai);
1.49 markus 333: if (sock < 0)
1.110 markus 334: /* Any error is already output */
1.49 markus 335: continue;
336:
1.141 djm 337: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
338: options.connection_timeout) >= 0) {
1.49 markus 339: /* Successful connection. */
1.102 markus 340: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 341: break;
1.49 markus 342: } else {
1.131 itojun 343: debug("connect to address %s port %s: %s",
344: ntop, strport, strerror(errno));
1.40 markus 345: /*
346: * Close the failed socket; there appear to
347: * be some problems when reusing a socket for
348: * which connect() has already returned an
349: * error.
350: */
1.38 markus 351: close(sock);
352: }
353: }
1.49 markus 354: if (ai)
355: break; /* Successful connection. */
1.1 deraadt 356:
1.110 markus 357: attempt++;
358: if (attempt >= connection_attempts)
359: break;
1.38 markus 360: /* Sleep a moment before retrying. */
361: sleep(1);
362: }
1.49 markus 363:
364: freeaddrinfo(aitop);
365:
1.38 markus 366: /* Return failure if we didn't get a successful connection. */
1.130 itojun 367: if (attempt >= connection_attempts) {
1.159 markus 368: error("ssh: connect to host %s port %s: %s",
1.130 itojun 369: host, strport, strerror(errno));
1.159 markus 370: return (-1);
1.130 itojun 371: }
1.38 markus 372:
373: debug("Connection established.");
1.90 markus 374:
1.155 markus 375: /* Set SO_KEEPALIVE if requested. */
376: if (options.tcp_keep_alive &&
1.90 markus 377: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
378: sizeof(on)) < 0)
379: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 380:
381: /* Set the connection. */
382: packet_set_connection(sock, sock);
1.1 deraadt 383:
1.110 markus 384: return 0;
1.59 markus 385: }
386:
1.43 markus 387: /*
1.39 deraadt 388: * Waits for the server identification string, and sends our own
389: * identification string.
390: */
1.109 itojun 391: static void
1.95 itojun 392: ssh_exchange_identification(void)
1.1 deraadt 393: {
1.38 markus 394: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 395: int remote_major, remote_minor, mismatch;
1.38 markus 396: int connection_in = packet_get_connection_in();
397: int connection_out = packet_get_connection_out();
1.93 stevesk 398: int minor1 = PROTOCOL_MINOR_1;
1.165 djm 399: u_int i;
1.38 markus 400:
1.163 avsm 401: /* Read other side's version identification. */
1.75 markus 402: for (;;) {
403: for (i = 0; i < sizeof(buf) - 1; i++) {
1.163 avsm 404: size_t len = atomicio(read, connection_in, &buf[i], 1);
405:
1.167 djm 406: if (len != 1 && errno == EPIPE)
1.163 avsm 407: fatal("ssh_exchange_identification: Connection closed by remote host");
408: else if (len != 1)
1.75 markus 409: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
410: if (buf[i] == '\r') {
411: buf[i] = '\n';
412: buf[i + 1] = 0;
413: continue; /**XXX wait for \n */
414: }
415: if (buf[i] == '\n') {
416: buf[i + 1] = 0;
417: break;
418: }
1.38 markus 419: }
1.75 markus 420: buf[sizeof(buf) - 1] = 0;
1.76 markus 421: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 422: break;
1.75 markus 423: debug("ssh_exchange_identification: %s", buf);
1.38 markus 424: }
1.59 markus 425: server_version_string = xstrdup(buf);
1.38 markus 426:
1.40 markus 427: /*
428: * Check that the versions match. In future this might accept
429: * several versions and set appropriate flags to handle them.
430: */
1.59 markus 431: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
432: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 433: fatal("Bad remote protocol version identification: '%.100s'", buf);
434: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 435: remote_major, remote_minor, remote_version);
1.38 markus 436:
1.59 markus 437: compat_datafellows(remote_version);
1.64 markus 438: mismatch = 0;
1.59 markus 439:
1.116 deraadt 440: switch (remote_major) {
1.64 markus 441: case 1:
442: if (remote_minor == 99 &&
443: (options.protocol & SSH_PROTO_2) &&
444: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
445: enable_compat20();
446: break;
447: }
448: if (!(options.protocol & SSH_PROTO_1)) {
449: mismatch = 1;
450: break;
451: }
452: if (remote_minor < 3) {
453: fatal("Remote machine has too old SSH software version.");
1.81 markus 454: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 455: /* We speak 1.3, too. */
456: enable_compat13();
1.81 markus 457: minor1 = 3;
1.64 markus 458: if (options.forward_agent) {
1.138 itojun 459: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 460: options.forward_agent = 0;
461: }
462: }
463: break;
464: case 2:
465: if (options.protocol & SSH_PROTO_2) {
466: enable_compat20();
467: break;
1.38 markus 468: }
1.64 markus 469: /* FALLTHROUGH */
1.68 markus 470: default:
1.64 markus 471: mismatch = 1;
472: break;
1.38 markus 473: }
1.64 markus 474: if (mismatch)
1.38 markus 475: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 476: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
477: remote_major);
1.38 markus 478: /* Send our own protocol version identification. */
479: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 480: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 481: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 482: SSH_VERSION);
1.146 deraadt 483: if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 484: fatal("write: %.100s", strerror(errno));
1.59 markus 485: client_version_string = xstrdup(buf);
486: chop(client_version_string);
487: chop(server_version_string);
488: debug("Local version string %.100s", client_version_string);
1.1 deraadt 489: }
490:
1.96 markus 491: /* defaults to 'no' */
1.109 itojun 492: static int
1.112 markus 493: confirm(const char *prompt)
1.1 deraadt 494: {
1.119 markus 495: const char *msg, *again = "Please type 'yes' or 'no': ";
496: char *p;
497: int ret = -1;
1.96 markus 498:
499: if (options.batch_mode)
500: return 0;
1.119 markus 501: for (msg = prompt;;msg = again) {
502: p = read_passphrase(msg, RP_ECHO);
503: if (p == NULL ||
504: (p[0] == '\0') || (p[0] == '\n') ||
505: strncasecmp(p, "no", 2) == 0)
506: ret = 0;
1.127 markus 507: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 508: ret = 1;
509: if (p)
510: xfree(p);
511: if (ret != -1)
512: return ret;
1.1 deraadt 513: }
514: }
515:
1.39 deraadt 516: /*
1.108 markus 517: * check whether the supplied host key is valid, return -1 if the key
518: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 519: */
1.109 itojun 520: static int
1.70 markus 521: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 522: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 523: {
1.58 markus 524: Key *file_key;
1.152 jakob 525: const char *type = key_type(host_key);
1.46 markus 526: char *ip = NULL;
1.100 markus 527: char hostline[1000], *hostp, *fp;
1.38 markus 528: HostStatus host_status;
529: HostStatus ip_status;
1.161 djm 530: int r, local = 0, host_ip_differ = 0;
1.49 markus 531: char ntop[NI_MAXHOST];
1.119 markus 532: char msg[1024];
1.145 jakob 533: int len, host_line, ip_line;
1.85 markus 534: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 535:
536: /*
537: * Force accepting of the host key for loopback/localhost. The
538: * problem is that if the home directory is NFS-mounted to multiple
539: * machines, localhost will refer to a different machine in each of
540: * them, and the user will get bogus HOST_CHANGED warnings. This
541: * essentially disables host authentication for localhost; however,
542: * this is probably not a real problem.
543: */
1.70 markus 544: /** hostaddr == 0! */
1.49 markus 545: switch (hostaddr->sa_family) {
546: case AF_INET:
1.108 markus 547: local = (ntohl(((struct sockaddr_in *)hostaddr)->
1.168 djm 548: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 549: break;
550: case AF_INET6:
1.108 markus 551: local = IN6_IS_ADDR_LOOPBACK(
552: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 553: break;
554: default:
555: local = 0;
556: break;
557: }
1.111 markus 558: if (options.no_host_authentication_for_localhost == 1 && local &&
559: options.host_key_alias == NULL) {
1.88 markus 560: debug("Forcing accepting of host key for "
561: "loopback/localhost.");
1.108 markus 562: return 0;
1.49 markus 563: }
1.42 markus 564:
565: /*
1.88 markus 566: * We don't have the remote ip-address for connections
567: * using a proxy command
1.42 markus 568: */
1.84 markus 569: if (options.proxy_command == NULL) {
570: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 571: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 572: fatal("check_host_key: getnameinfo failed");
573: ip = xstrdup(ntop);
574: } else {
575: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 576: }
1.88 markus 577: /*
578: * Turn off check_host_ip if the connection is to localhost, via proxy
579: * command or if we don't have a hostname to compare with
580: */
581: if (options.check_host_ip &&
582: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
583: options.check_host_ip = 0;
1.86 markus 584:
585: /*
586: * Allow the user to record the key under a different name. This is
587: * useful for ssh tunneling over forwarded connections or if you run
588: * multiple sshd's on different ports on the same machine.
589: */
590: if (options.host_key_alias != NULL) {
591: host = options.host_key_alias;
592: debug("using hostkeyalias: %s", host);
1.84 markus 593: }
1.38 markus 594:
1.46 markus 595: /*
596: * Store the host key from the known host file in here so that we can
597: * compare it with the key for the IP address.
598: */
1.58 markus 599: file_key = key_new(host_key->type);
1.38 markus 600:
1.40 markus 601: /*
1.170 djm 602: * Check if the host key is present in the user's list of known
1.40 markus 603: * hosts or in the systemwide list.
604: */
1.85 markus 605: host_file = user_hostfile;
1.108 markus 606: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 607: file_key, &host_line);
1.85 markus 608: if (host_status == HOST_NEW) {
609: host_file = system_hostfile;
1.108 markus 610: host_status = check_host_in_hostfile(host_file, host, host_key,
611: file_key, &host_line);
1.85 markus 612: }
1.40 markus 613: /*
614: * Also perform check for the ip address, skip the check if we are
615: * localhost or the hostname was an ip address to begin with
616: */
1.88 markus 617: if (options.check_host_ip) {
1.58 markus 618: Key *ip_key = key_new(host_key->type);
1.38 markus 619:
1.85 markus 620: ip_file = user_hostfile;
1.108 markus 621: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
622: ip_key, &ip_line);
1.85 markus 623: if (ip_status == HOST_NEW) {
624: ip_file = system_hostfile;
1.108 markus 625: ip_status = check_host_in_hostfile(ip_file, ip,
626: host_key, ip_key, &ip_line);
1.85 markus 627: }
1.38 markus 628: if (host_status == HOST_CHANGED &&
1.58 markus 629: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 630: host_ip_differ = 1;
631:
1.58 markus 632: key_free(ip_key);
1.38 markus 633: } else
634: ip_status = host_status;
635:
1.58 markus 636: key_free(file_key);
1.38 markus 637:
638: switch (host_status) {
639: case HOST_OK:
640: /* The host is known and the key matches. */
1.72 markus 641: debug("Host '%.200s' is known and matches the %s host key.",
642: host, type);
1.85 markus 643: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 644: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 645: if (readonly)
1.138 itojun 646: logit("%s host key for IP address "
1.108 markus 647: "'%.128s' not in list of known hosts.",
648: type, ip);
649: else if (!add_host_to_hostfile(user_hostfile, ip,
1.160 djm 650: host_key, options.hash_known_hosts))
1.138 itojun 651: logit("Failed to add the %s host key for IP "
1.108 markus 652: "address '%.128s' to the list of known "
653: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 654: else
1.138 itojun 655: logit("Warning: Permanently added the %s host "
1.108 markus 656: "key for IP address '%.128s' to the list "
657: "of known hosts.", type, ip);
1.38 markus 658: }
659: break;
660: case HOST_NEW:
1.108 markus 661: if (readonly)
662: goto fail;
1.38 markus 663: /* The host is new. */
664: if (options.strict_host_key_checking == 1) {
1.108 markus 665: /*
666: * User has requested strict host key checking. We
667: * will not add the host key automatically. The only
668: * alternative left is to abort.
669: */
670: error("No %s host key is known for %.200s and you "
671: "have requested strict checking.", type, host);
672: goto fail;
1.38 markus 673: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 674: char msg1[1024], msg2[1024];
675:
676: if (show_other_keys(host, host_key))
677: snprintf(msg1, sizeof(msg1),
1.168 djm 678: "\nbut keys of different type are already"
679: " known for this host.");
1.145 jakob 680: else
681: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 682: /* The default */
1.100 markus 683: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.145 jakob 684: msg2[0] = '\0';
685: if (options.verify_host_key_dns) {
1.153 jakob 686: if (matching_host_key_dns)
1.145 jakob 687: snprintf(msg2, sizeof(msg2),
688: "Matching host key fingerprint"
689: " found in DNS.\n");
690: else
691: snprintf(msg2, sizeof(msg2),
692: "No matching host key fingerprint"
693: " found in DNS.\n");
694: }
1.119 markus 695: snprintf(msg, sizeof(msg),
1.108 markus 696: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 697: "established%s\n"
1.145 jakob 698: "%s key fingerprint is %s.\n%s"
1.108 markus 699: "Are you sure you want to continue connecting "
1.132 markus 700: "(yes/no)? ",
1.145 jakob 701: host, ip, msg1, type, fp, msg2);
1.100 markus 702: xfree(fp);
1.119 markus 703: if (!confirm(msg))
1.108 markus 704: goto fail;
1.38 markus 705: }
1.161 djm 706: /*
707: * If not in strict mode, add the key automatically to the
708: * local known_hosts file.
709: */
1.88 markus 710: if (options.check_host_ip && ip_status == HOST_NEW) {
1.161 djm 711: snprintf(hostline, sizeof(hostline), "%s,%s",
712: host, ip);
1.38 markus 713: hostp = hostline;
1.161 djm 714: if (options.hash_known_hosts) {
715: /* Add hash of host and IP separately */
716: r = add_host_to_hostfile(user_hostfile, host,
717: host_key, options.hash_known_hosts) &&
718: add_host_to_hostfile(user_hostfile, ip,
719: host_key, options.hash_known_hosts);
720: } else {
721: /* Add unhashed "host,ip" */
722: r = add_host_to_hostfile(user_hostfile,
723: hostline, host_key,
724: options.hash_known_hosts);
725: }
726: } else {
727: r = add_host_to_hostfile(user_hostfile, host, host_key,
728: options.hash_known_hosts);
1.38 markus 729: hostp = host;
1.161 djm 730: }
1.38 markus 731:
1.161 djm 732: if (!r)
1.138 itojun 733: logit("Failed to add the host to the list of known "
1.108 markus 734: "hosts (%.500s).", user_hostfile);
1.38 markus 735: else
1.138 itojun 736: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 737: "list of known hosts.", hostp, type);
1.38 markus 738: break;
739: case HOST_CHANGED:
740: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 741: char *key_msg;
1.38 markus 742: if (ip_status == HOST_NEW)
1.158 avsm 743: key_msg = "is unknown";
1.38 markus 744: else if (ip_status == HOST_OK)
1.158 avsm 745: key_msg = "is unchanged";
1.38 markus 746: else
1.158 avsm 747: key_msg = "has a different value";
1.38 markus 748: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
749: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
750: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 751: error("The %s host key for %s has changed,", type, host);
1.38 markus 752: error("and the key for the according IP address %s", ip);
1.158 avsm 753: error("%s. This could either mean that", key_msg);
1.38 markus 754: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 755: error("and its host key have changed at the same time.");
1.88 markus 756: if (ip_status != HOST_NEW)
1.85 markus 757: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 758: }
759: /* The host key has changed. */
1.150 jakob 760: warn_changed_key(host_key);
1.38 markus 761: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 762: user_hostfile);
1.85 markus 763: error("Offending key in %s:%d", host_file, host_line);
1.38 markus 764:
1.40 markus 765: /*
766: * If strict host key checking is in use, the user will have
767: * to edit the key manually and we can only abort.
768: */
1.108 markus 769: if (options.strict_host_key_checking) {
770: error("%s host key for %.200s has changed and you have "
771: "requested strict checking.", type, host);
772: goto fail;
773: }
1.38 markus 774:
1.40 markus 775: /*
776: * If strict host key checking has not been requested, allow
1.144 djm 777: * the connection but without MITM-able authentication or
1.40 markus 778: * agent forwarding.
779: */
1.38 markus 780: if (options.password_authentication) {
1.108 markus 781: error("Password authentication is disabled to avoid "
782: "man-in-the-middle attacks.");
1.38 markus 783: options.password_authentication = 0;
1.144 djm 784: }
785: if (options.kbd_interactive_authentication) {
786: error("Keyboard-interactive authentication is disabled"
787: " to avoid man-in-the-middle attacks.");
788: options.kbd_interactive_authentication = 0;
789: options.challenge_response_authentication = 0;
790: }
791: if (options.challenge_response_authentication) {
792: error("Challenge/response authentication is disabled"
793: " to avoid man-in-the-middle attacks.");
794: options.challenge_response_authentication = 0;
1.38 markus 795: }
796: if (options.forward_agent) {
1.108 markus 797: error("Agent forwarding is disabled to avoid "
798: "man-in-the-middle attacks.");
1.38 markus 799: options.forward_agent = 0;
1.83 markus 800: }
801: if (options.forward_x11) {
1.108 markus 802: error("X11 forwarding is disabled to avoid "
803: "man-in-the-middle attacks.");
1.83 markus 804: options.forward_x11 = 0;
805: }
1.108 markus 806: if (options.num_local_forwards > 0 ||
807: options.num_remote_forwards > 0) {
808: error("Port forwarding is disabled to avoid "
809: "man-in-the-middle attacks.");
810: options.num_local_forwards =
1.118 deraadt 811: options.num_remote_forwards = 0;
1.38 markus 812: }
1.40 markus 813: /*
814: * XXX Should permit the user to change to use the new id.
815: * This could be done by converting the host key to an
816: * identifying sentence, tell that the host identifies itself
817: * by that sentence, and ask the user if he/she whishes to
818: * accept the authentication.
819: */
1.38 markus 820: break;
1.132 markus 821: case HOST_FOUND:
822: fatal("internal error");
823: break;
1.88 markus 824: }
825:
826: if (options.check_host_ip && host_status != HOST_CHANGED &&
827: ip_status == HOST_CHANGED) {
1.119 markus 828: snprintf(msg, sizeof(msg),
829: "Warning: the %s host key for '%.200s' "
830: "differs from the key for the IP address '%.128s'"
831: "\nOffending key for IP in %s:%d",
832: type, host, ip, ip_file, ip_line);
833: if (host_status == HOST_OK) {
834: len = strlen(msg);
835: snprintf(msg + len, sizeof(msg) - len,
836: "\nMatching host key in %s:%d",
1.125 deraadt 837: host_file, host_line);
1.119 markus 838: }
1.88 markus 839: if (options.strict_host_key_checking == 1) {
1.143 djm 840: logit("%s", msg);
1.108 markus 841: error("Exiting, you have requested strict checking.");
842: goto fail;
1.88 markus 843: } else if (options.strict_host_key_checking == 2) {
1.119 markus 844: strlcat(msg, "\nAre you sure you want "
845: "to continue connecting (yes/no)? ", sizeof(msg));
846: if (!confirm(msg))
1.108 markus 847: goto fail;
1.119 markus 848: } else {
1.143 djm 849: logit("%s", msg);
1.88 markus 850: }
1.38 markus 851: }
1.82 provos 852:
853: xfree(ip);
1.108 markus 854: return 0;
855:
856: fail:
857: xfree(ip);
858: return -1;
859: }
860:
1.140 jakob 861: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 862: int
863: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
864: {
865: struct stat st;
1.153 jakob 866: int flags = 0;
1.140 jakob 867:
1.153 jakob 868: if (options.verify_host_key_dns &&
869: verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
870:
871: if (flags & DNS_VERIFY_FOUND) {
872:
873: if (options.verify_host_key_dns == 1 &&
874: flags & DNS_VERIFY_MATCH &&
875: flags & DNS_VERIFY_SECURE)
876: return 0;
877:
878: if (flags & DNS_VERIFY_MATCH) {
879: matching_host_key_dns = 1;
880: } else {
881: warn_changed_key(host_key);
882: error("Update the SSHFP RR in DNS with the new "
883: "host key to get rid of this message.");
884: }
1.140 jakob 885: }
886: }
1.108 markus 887:
888: /* return ok if the key can be found in an old keyfile */
889: if (stat(options.system_hostfile2, &st) == 0 ||
890: stat(options.user_hostfile2, &st) == 0) {
891: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
892: options.user_hostfile2, options.system_hostfile2) == 0)
893: return 0;
894: }
895: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
896: options.user_hostfile, options.system_hostfile);
1.51 markus 897: }
1.70 markus 898:
1.51 markus 899: /*
900: * Starts a dialog with the server, and authenticates the current user on the
901: * server. This does not need any extra privileges. The basic connection
902: * to the server must already have been established before this is called.
903: * If login fails, this function prints an error and never returns.
904: * This function does not require super-user privileges.
905: */
906: void
1.120 markus 907: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 908: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 909: {
910: char *host, *cp;
1.70 markus 911: char *server_user, *local_user;
912:
913: local_user = xstrdup(pw->pw_name);
914: server_user = options.user ? options.user : local_user;
1.51 markus 915:
916: /* Convert the user-supplied hostname into all lowercase. */
917: host = xstrdup(orighost);
918: for (cp = host; *cp; cp++)
919: if (isupper(*cp))
920: *cp = tolower(*cp);
921:
922: /* Exchange protocol version identification strings with the server. */
923: ssh_exchange_identification();
924:
925: /* Put the connection into non-blocking mode. */
926: packet_set_nonblocking();
927:
928: /* key exchange */
929: /* authenticate user */
1.59 markus 930: if (compat20) {
931: ssh_kex2(host, hostaddr);
1.120 markus 932: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 933: } else {
934: ssh_kex(host, hostaddr);
1.120 markus 935: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 936: }
1.97 markus 937: }
938:
939: void
940: ssh_put_password(char *password)
941: {
942: int size;
943: char *padded;
944:
1.99 deraadt 945: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 946: packet_put_cstring(password);
1.99 deraadt 947: return;
948: }
1.97 markus 949: size = roundup(strlen(password) + 1, 32);
950: padded = xmalloc(size);
951: memset(padded, 0, size);
952: strlcpy(padded, password, size);
953: packet_put_string(padded, size);
954: memset(padded, 0, size);
955: xfree(padded);
1.132 markus 956: }
957:
958: static int
959: show_key_from_file(const char *file, const char *host, int keytype)
960: {
961: Key *found;
962: char *fp;
963: int line, ret;
964:
965: found = key_new(keytype);
966: if ((ret = lookup_key_in_hostfile_by_type(file, host,
967: keytype, found, &line))) {
968: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 969: logit("WARNING: %s key found for host %s\n"
1.133 markus 970: "in %s:%d\n"
1.132 markus 971: "%s key fingerprint %s.",
972: key_type(found), host, file, line,
973: key_type(found), fp);
974: xfree(fp);
975: }
976: key_free(found);
977: return (ret);
978: }
979:
980: /* print all known host keys for a given host, but skip keys of given type */
981: static int
982: show_other_keys(const char *host, Key *key)
983: {
984: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
985: int i, found = 0;
986:
987: for (i = 0; type[i] != -1; i++) {
988: if (type[i] == key->type)
989: continue;
990: if (type[i] != KEY_RSA1 &&
991: show_key_from_file(options.user_hostfile2, host, type[i])) {
992: found = 1;
993: continue;
994: }
995: if (type[i] != KEY_RSA1 &&
996: show_key_from_file(options.system_hostfile2, host, type[i])) {
997: found = 1;
998: continue;
999: }
1000: if (show_key_from_file(options.user_hostfile, host, type[i])) {
1001: found = 1;
1002: continue;
1003: }
1004: if (show_key_from_file(options.system_hostfile, host, type[i])) {
1005: found = 1;
1006: continue;
1007: }
1008: debug2("no key of type %d for host %s", type[i], host);
1009: }
1010: return (found);
1.150 jakob 1011: }
1012:
1013: static void
1014: warn_changed_key(Key *host_key)
1015: {
1016: char *fp;
1.151 jakob 1017: const char *type = key_type(host_key);
1.150 jakob 1018:
1019: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1020:
1021: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1022: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1023: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1024: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1025: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1026: error("It is also possible that the %s host key has just been changed.", type);
1027: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1028: type, fp);
1029: error("Please contact your system administrator.");
1030:
1031: xfree(fp);
1.171 reyk 1032: }
1033:
1034: /*
1035: * Execute a local command
1036: */
1037: int
1038: ssh_local_cmd(const char *args)
1039: {
1040: char *shell;
1041: pid_t pid;
1042: int status;
1043:
1044: if (!options.permit_local_command ||
1045: args == NULL || !*args)
1046: return (1);
1047:
1048: if ((shell = getenv("SHELL")) == NULL)
1049: shell = _PATH_BSHELL;
1050:
1051: pid = fork();
1052: if (pid == 0) {
1053: debug3("Executing %s -c \"%s\"", shell, args);
1054: execl(shell, shell, "-c", args, (char *)NULL);
1055: error("Couldn't execute %s -c \"%s\": %s",
1056: shell, args, strerror(errno));
1057: _exit(1);
1058: } else if (pid == -1)
1059: fatal("fork failed: %.100s", strerror(errno));
1060: while (waitpid(pid, &status, 0) == -1)
1061: if (errno != EINTR)
1062: fatal("Couldn't wait for child: %s", strerror(errno));
1063:
1064: if (!WIFEXITED(status))
1065: return (1);
1066:
1067: return (WEXITSTATUS(status));
1.1 deraadt 1068: }
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