Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.183
1.183 ! markus 1: /* $OpenBSD: sshconnect.c,v 1.182 2006/05/17 12:43:34 markus Exp $ */
1.1 deraadt 2: /*
1.39 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Code to connect to a remote host, and to perform the client side of the
7: * login (authentication) dialog.
1.78 deraadt 8: *
9: * As far as I am concerned, the code I have written for this software
10: * can be used freely for any purpose. Any derived versions of this
11: * software must be clearly marked as such, and if the derived work is
12: * incompatible with the protocol description in the RFC file, it must be
13: * called by a name other than "ssh" or "Secure Shell".
1.39 deraadt 14: */
1.1 deraadt 15:
16: #include "includes.h"
1.174 stevesk 17:
18: #include <sys/types.h>
19: #include <sys/wait.h>
1.175 stevesk 20: #include <sys/stat.h>
1.172 stevesk 21:
1.176 stevesk 22: #include <ctype.h>
1.172 stevesk 23: #include <paths.h>
1.71 markus 24:
1.91 markus 25: #include "ssh.h"
1.1 deraadt 26: #include "xmalloc.h"
27: #include "rsa.h"
1.59 markus 28: #include "buffer.h"
1.1 deraadt 29: #include "packet.h"
30: #include "uidswap.h"
1.21 markus 31: #include "compat.h"
1.58 markus 32: #include "key.h"
1.71 markus 33: #include "sshconnect.h"
1.58 markus 34: #include "hostfile.h"
1.91 markus 35: #include "log.h"
36: #include "readconf.h"
37: #include "atomicio.h"
38: #include "misc.h"
1.140 jakob 39: #include "dns.h"
40:
1.70 markus 41: char *client_version_string = NULL;
42: char *server_version_string = NULL;
1.59 markus 43:
1.169 stevesk 44: static int matching_host_key_dns = 0;
1.145 jakob 45:
1.124 markus 46: /* import */
1.43 markus 47: extern Options options;
1.50 markus 48: extern char *__progname;
1.124 markus 49: extern uid_t original_real_uid;
50: extern uid_t original_effective_uid;
1.135 djm 51: extern pid_t proxy_command_pid;
1.91 markus 52:
1.132 markus 53: static int show_other_keys(const char *, Key *);
1.150 jakob 54: static void warn_changed_key(Key *);
1.132 markus 55:
1.39 deraadt 56: /*
57: * Connect to the given ssh server using a proxy command.
58: */
1.109 itojun 59: static int
1.124 markus 60: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 61: {
1.164 djm 62: char *command_string, *tmp;
1.38 markus 63: int pin[2], pout[2];
1.69 deraadt 64: pid_t pid;
1.49 markus 65: char strport[NI_MAXSERV];
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: */
1.179 djm 77: xasprintf(&tmp, "exec %s", proxy_command);
1.164 djm 78: command_string = percent_expand(tmp, "h", host,
79: "p", strport, (char *)NULL);
80: xfree(tmp);
1.38 markus 81:
82: /* Create pipes for communicating with the proxy. */
83: if (pipe(pin) < 0 || pipe(pout) < 0)
84: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 85: strerror(errno));
1.38 markus 86:
87: debug("Executing proxy command: %.500s", command_string);
88:
89: /* Fork and execute the proxy command. */
90: if ((pid = fork()) == 0) {
91: char *argv[10];
92:
93: /* Child. Permanently give up superuser privileges. */
1.183 ! markus 94: permanently_set_uid(getpwuid(original_real_uid));
1.38 markus 95:
96: /* Redirect stdin and stdout. */
97: close(pin[1]);
98: if (pin[0] != 0) {
99: if (dup2(pin[0], 0) < 0)
100: perror("dup2 stdin");
101: close(pin[0]);
102: }
103: close(pout[0]);
104: if (dup2(pout[1], 1) < 0)
105: perror("dup2 stdout");
106: /* Cannot be 1 because pin allocated two descriptors. */
107: close(pout[1]);
108:
109: /* Stderr is left as it is so that error messages get
110: printed on the user's terminal. */
1.89 markus 111: argv[0] = _PATH_BSHELL;
1.38 markus 112: argv[1] = "-c";
113: argv[2] = command_string;
114: argv[3] = NULL;
115:
116: /* Execute the proxy command. Note that we gave up any
117: extra privileges above. */
1.89 markus 118: execv(argv[0], argv);
119: perror(argv[0]);
1.38 markus 120: exit(1);
121: }
122: /* Parent. */
123: if (pid < 0)
124: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 125: else
126: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 127:
128: /* Close child side of the descriptors. */
129: close(pin[0]);
130: close(pout[1]);
131:
132: /* Free the command name. */
1.164 djm 133: xfree(command_string);
1.38 markus 134:
135: /* Set the connection file descriptors. */
136: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 137:
1.110 markus 138: /* Indicate OK return */
139: return 0;
1.1 deraadt 140: }
141:
1.39 deraadt 142: /*
143: * Creates a (possibly privileged) socket for use as the ssh connection.
144: */
1.109 itojun 145: static int
1.139 markus 146: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 147: {
1.105 markus 148: int sock, gaierr;
149: struct addrinfo hints, *res;
1.1 deraadt 150:
1.40 markus 151: /*
152: * If we are running as root and want to connect to a privileged
153: * port, bind our own socket to a privileged port.
154: */
1.38 markus 155: if (privileged) {
156: int p = IPPORT_RESERVED - 1;
1.124 markus 157: PRIV_START;
1.139 markus 158: sock = rresvport_af(&p, ai->ai_family);
1.124 markus 159: PRIV_END;
1.38 markus 160: if (sock < 0)
1.139 markus 161: error("rresvport: af=%d %.100s", ai->ai_family,
162: strerror(errno));
1.55 markus 163: else
164: debug("Allocated local port %d.", p);
1.105 markus 165: return sock;
166: }
1.139 markus 167: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.105 markus 168: if (sock < 0)
169: error("socket: %.100s", strerror(errno));
170:
171: /* Bind the socket to an alternative local IP address */
172: if (options.bind_address == NULL)
173: return sock;
174:
175: memset(&hints, 0, sizeof(hints));
1.139 markus 176: hints.ai_family = ai->ai_family;
177: hints.ai_socktype = ai->ai_socktype;
178: hints.ai_protocol = ai->ai_protocol;
1.105 markus 179: hints.ai_flags = AI_PASSIVE;
180: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
181: if (gaierr) {
182: error("getaddrinfo: %s: %s", options.bind_address,
183: gai_strerror(gaierr));
184: close(sock);
185: return -1;
186: }
187: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
188: error("bind: %s: %s", options.bind_address, strerror(errno));
189: close(sock);
190: freeaddrinfo(res);
191: return -1;
1.38 markus 192: }
1.105 markus 193: freeaddrinfo(res);
1.38 markus 194: return sock;
1.1 deraadt 195: }
196:
1.141 djm 197: static int
198: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
199: socklen_t addrlen, int timeout)
200: {
201: fd_set *fdset;
202: struct timeval tv;
203: socklen_t optlen;
1.179 djm 204: int optval, rc, result = -1;
1.141 djm 205:
206: if (timeout <= 0)
207: return (connect(sockfd, serv_addr, addrlen));
208:
1.156 djm 209: set_nonblock(sockfd);
1.141 djm 210: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 211: if (rc == 0) {
212: unset_nonblock(sockfd);
1.141 djm 213: return (0);
1.156 djm 214: }
1.141 djm 215: if (errno != EINPROGRESS)
216: return (-1);
217:
1.179 djm 218: fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
219: sizeof(fd_mask));
1.141 djm 220: FD_SET(sockfd, fdset);
221: tv.tv_sec = timeout;
222: tv.tv_usec = 0;
223:
1.162 deraadt 224: for (;;) {
1.141 djm 225: rc = select(sockfd + 1, NULL, fdset, NULL, &tv);
226: if (rc != -1 || errno != EINTR)
227: break;
228: }
229:
1.162 deraadt 230: switch (rc) {
1.141 djm 231: case 0:
232: /* Timed out */
233: errno = ETIMEDOUT;
1.142 djm 234: break;
1.141 djm 235: case -1:
236: /* Select error */
1.154 djm 237: debug("select: %s", strerror(errno));
1.142 djm 238: break;
1.141 djm 239: case 1:
240: /* Completed or failed */
241: optval = 0;
242: optlen = sizeof(optval);
1.154 djm 243: if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &optval,
1.148 markus 244: &optlen) == -1) {
1.154 djm 245: debug("getsockopt: %s", strerror(errno));
1.142 djm 246: break;
1.148 markus 247: }
1.141 djm 248: if (optval != 0) {
249: errno = optval;
1.142 djm 250: break;
1.141 djm 251: }
1.142 djm 252: result = 0;
1.156 djm 253: unset_nonblock(sockfd);
1.141 djm 254: break;
255: default:
256: /* Should not occur */
257: fatal("Bogus return (%d) from select()", rc);
258: }
259:
1.142 djm 260: xfree(fdset);
261: return (result);
1.141 djm 262: }
263:
1.39 deraadt 264: /*
1.49 markus 265: * Opens a TCP/IP connection to the remote server on the given host.
266: * The address of the remote host will be returned in hostaddr.
1.124 markus 267: * If port is 0, the default port will be used. If needpriv is true,
1.39 deraadt 268: * a privileged port will be allocated to make the connection.
1.124 markus 269: * This requires super-user privileges if needpriv is true.
1.39 deraadt 270: * Connection_attempts specifies the maximum number of tries (one per
271: * second). If proxy_command is non-NULL, it specifies the command (with %h
272: * and %p substituted for host and port, respectively) to use to contact
273: * the daemon.
274: */
1.38 markus 275: int
1.49 markus 276: ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
1.115 markus 277: u_short port, int family, int connection_attempts,
1.124 markus 278: int needpriv, const char *proxy_command)
1.1 deraadt 279: {
1.90 markus 280: int gaierr;
281: int on = 1;
1.49 markus 282: int sock = -1, attempt;
1.90 markus 283: char ntop[NI_MAXHOST], strport[NI_MAXSERV];
1.49 markus 284: struct addrinfo hints, *ai, *aitop;
1.38 markus 285:
1.136 markus 286: debug2("ssh_connect: needpriv %d", needpriv);
1.38 markus 287:
288: /* If a proxy command is given, connect using it. */
289: if (proxy_command != NULL)
1.124 markus 290: return ssh_proxy_connect(host, port, proxy_command);
1.38 markus 291:
292: /* No proxy command. */
293:
1.49 markus 294: memset(&hints, 0, sizeof(hints));
1.115 markus 295: hints.ai_family = family;
1.49 markus 296: hints.ai_socktype = SOCK_STREAM;
1.126 deraadt 297: snprintf(strport, sizeof strport, "%u", port);
1.49 markus 298: if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
1.50 markus 299: fatal("%s: %.100s: %s", __progname, host,
300: gai_strerror(gaierr));
1.38 markus 301:
1.181 markus 302: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.38 markus 303: if (attempt > 0)
304: debug("Trying again...");
305:
1.181 markus 306: /*
307: * Loop through addresses for this host, and try each one in
308: * sequence until the connection succeeds.
309: */
1.49 markus 310: for (ai = aitop; ai; ai = ai->ai_next) {
311: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
312: continue;
313: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
314: ntop, sizeof(ntop), strport, sizeof(strport),
315: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
316: error("ssh_connect: getnameinfo failed");
317: continue;
318: }
319: debug("Connecting to %.200s [%.100s] port %s.",
320: host, ntop, strport);
321:
322: /* Create a socket for connecting. */
1.139 markus 323: sock = ssh_create_socket(needpriv, ai);
1.49 markus 324: if (sock < 0)
1.110 markus 325: /* Any error is already output */
1.49 markus 326: continue;
327:
1.141 djm 328: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
329: options.connection_timeout) >= 0) {
1.49 markus 330: /* Successful connection. */
1.102 markus 331: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 332: break;
1.49 markus 333: } else {
1.131 itojun 334: debug("connect to address %s port %s: %s",
335: ntop, strport, strerror(errno));
1.38 markus 336: close(sock);
1.181 markus 337: sock = -1;
1.38 markus 338: }
339: }
1.181 markus 340: if (sock != -1)
1.49 markus 341: break; /* Successful connection. */
1.1 deraadt 342:
1.38 markus 343: /* Sleep a moment before retrying. */
344: sleep(1);
345: }
1.49 markus 346:
347: freeaddrinfo(aitop);
348:
1.38 markus 349: /* Return failure if we didn't get a successful connection. */
1.181 markus 350: if (sock == -1) {
1.159 markus 351: error("ssh: connect to host %s port %s: %s",
1.130 itojun 352: host, strport, strerror(errno));
1.159 markus 353: return (-1);
1.130 itojun 354: }
1.38 markus 355:
356: debug("Connection established.");
1.90 markus 357:
1.155 markus 358: /* Set SO_KEEPALIVE if requested. */
359: if (options.tcp_keep_alive &&
1.90 markus 360: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
361: sizeof(on)) < 0)
362: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 363:
364: /* Set the connection. */
365: packet_set_connection(sock, sock);
1.1 deraadt 366:
1.110 markus 367: return 0;
1.59 markus 368: }
369:
1.43 markus 370: /*
1.39 deraadt 371: * Waits for the server identification string, and sends our own
372: * identification string.
373: */
1.109 itojun 374: static void
1.95 itojun 375: ssh_exchange_identification(void)
1.1 deraadt 376: {
1.38 markus 377: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 378: int remote_major, remote_minor, mismatch;
1.38 markus 379: int connection_in = packet_get_connection_in();
380: int connection_out = packet_get_connection_out();
1.93 stevesk 381: int minor1 = PROTOCOL_MINOR_1;
1.165 djm 382: u_int i;
1.38 markus 383:
1.163 avsm 384: /* Read other side's version identification. */
1.75 markus 385: for (;;) {
386: for (i = 0; i < sizeof(buf) - 1; i++) {
1.163 avsm 387: size_t len = atomicio(read, connection_in, &buf[i], 1);
388:
1.167 djm 389: if (len != 1 && errno == EPIPE)
1.163 avsm 390: fatal("ssh_exchange_identification: Connection closed by remote host");
391: else if (len != 1)
1.75 markus 392: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
393: if (buf[i] == '\r') {
394: buf[i] = '\n';
395: buf[i + 1] = 0;
396: continue; /**XXX wait for \n */
397: }
398: if (buf[i] == '\n') {
399: buf[i + 1] = 0;
400: break;
401: }
1.38 markus 402: }
1.75 markus 403: buf[sizeof(buf) - 1] = 0;
1.76 markus 404: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 405: break;
1.75 markus 406: debug("ssh_exchange_identification: %s", buf);
1.38 markus 407: }
1.59 markus 408: server_version_string = xstrdup(buf);
1.38 markus 409:
1.40 markus 410: /*
411: * Check that the versions match. In future this might accept
412: * several versions and set appropriate flags to handle them.
413: */
1.59 markus 414: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
415: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 416: fatal("Bad remote protocol version identification: '%.100s'", buf);
417: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 418: remote_major, remote_minor, remote_version);
1.38 markus 419:
1.59 markus 420: compat_datafellows(remote_version);
1.64 markus 421: mismatch = 0;
1.59 markus 422:
1.116 deraadt 423: switch (remote_major) {
1.64 markus 424: case 1:
425: if (remote_minor == 99 &&
426: (options.protocol & SSH_PROTO_2) &&
427: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
428: enable_compat20();
429: break;
430: }
431: if (!(options.protocol & SSH_PROTO_1)) {
432: mismatch = 1;
433: break;
434: }
435: if (remote_minor < 3) {
436: fatal("Remote machine has too old SSH software version.");
1.81 markus 437: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 438: /* We speak 1.3, too. */
439: enable_compat13();
1.81 markus 440: minor1 = 3;
1.64 markus 441: if (options.forward_agent) {
1.138 itojun 442: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 443: options.forward_agent = 0;
444: }
445: }
446: break;
447: case 2:
448: if (options.protocol & SSH_PROTO_2) {
449: enable_compat20();
450: break;
1.38 markus 451: }
1.64 markus 452: /* FALLTHROUGH */
1.68 markus 453: default:
1.64 markus 454: mismatch = 1;
455: break;
1.38 markus 456: }
1.64 markus 457: if (mismatch)
1.38 markus 458: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 459: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
460: remote_major);
1.38 markus 461: /* Send our own protocol version identification. */
462: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 463: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 464: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 465: SSH_VERSION);
1.146 deraadt 466: if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 467: fatal("write: %.100s", strerror(errno));
1.59 markus 468: client_version_string = xstrdup(buf);
469: chop(client_version_string);
470: chop(server_version_string);
471: debug("Local version string %.100s", client_version_string);
1.1 deraadt 472: }
473:
1.96 markus 474: /* defaults to 'no' */
1.109 itojun 475: static int
1.112 markus 476: confirm(const char *prompt)
1.1 deraadt 477: {
1.119 markus 478: const char *msg, *again = "Please type 'yes' or 'no': ";
479: char *p;
480: int ret = -1;
1.96 markus 481:
482: if (options.batch_mode)
483: return 0;
1.119 markus 484: for (msg = prompt;;msg = again) {
485: p = read_passphrase(msg, RP_ECHO);
486: if (p == NULL ||
487: (p[0] == '\0') || (p[0] == '\n') ||
488: strncasecmp(p, "no", 2) == 0)
489: ret = 0;
1.127 markus 490: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 491: ret = 1;
492: if (p)
493: xfree(p);
494: if (ret != -1)
495: return ret;
1.1 deraadt 496: }
497: }
498:
1.39 deraadt 499: /*
1.108 markus 500: * check whether the supplied host key is valid, return -1 if the key
501: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 502: */
1.109 itojun 503: static int
1.70 markus 504: check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 505: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 506: {
1.58 markus 507: Key *file_key;
1.152 jakob 508: const char *type = key_type(host_key);
1.46 markus 509: char *ip = NULL;
1.100 markus 510: char hostline[1000], *hostp, *fp;
1.38 markus 511: HostStatus host_status;
512: HostStatus ip_status;
1.161 djm 513: int r, local = 0, host_ip_differ = 0;
1.49 markus 514: char ntop[NI_MAXHOST];
1.119 markus 515: char msg[1024];
1.145 jakob 516: int len, host_line, ip_line;
1.85 markus 517: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 518:
519: /*
520: * Force accepting of the host key for loopback/localhost. The
521: * problem is that if the home directory is NFS-mounted to multiple
522: * machines, localhost will refer to a different machine in each of
523: * them, and the user will get bogus HOST_CHANGED warnings. This
524: * essentially disables host authentication for localhost; however,
525: * this is probably not a real problem.
526: */
1.70 markus 527: /** hostaddr == 0! */
1.49 markus 528: switch (hostaddr->sa_family) {
529: case AF_INET:
1.108 markus 530: local = (ntohl(((struct sockaddr_in *)hostaddr)->
1.168 djm 531: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 532: break;
533: case AF_INET6:
1.108 markus 534: local = IN6_IS_ADDR_LOOPBACK(
535: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 536: break;
537: default:
538: local = 0;
539: break;
540: }
1.111 markus 541: if (options.no_host_authentication_for_localhost == 1 && local &&
542: options.host_key_alias == NULL) {
1.88 markus 543: debug("Forcing accepting of host key for "
544: "loopback/localhost.");
1.108 markus 545: return 0;
1.49 markus 546: }
1.42 markus 547:
548: /*
1.88 markus 549: * We don't have the remote ip-address for connections
550: * using a proxy command
1.42 markus 551: */
1.84 markus 552: if (options.proxy_command == NULL) {
553: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 554: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 555: fatal("check_host_key: getnameinfo failed");
556: ip = xstrdup(ntop);
557: } else {
558: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 559: }
1.88 markus 560: /*
561: * Turn off check_host_ip if the connection is to localhost, via proxy
562: * command or if we don't have a hostname to compare with
563: */
564: if (options.check_host_ip &&
565: (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
566: options.check_host_ip = 0;
1.86 markus 567:
568: /*
569: * Allow the user to record the key under a different name. This is
570: * useful for ssh tunneling over forwarded connections or if you run
571: * multiple sshd's on different ports on the same machine.
572: */
573: if (options.host_key_alias != NULL) {
574: host = options.host_key_alias;
575: debug("using hostkeyalias: %s", host);
1.84 markus 576: }
1.38 markus 577:
1.46 markus 578: /*
579: * Store the host key from the known host file in here so that we can
580: * compare it with the key for the IP address.
581: */
1.58 markus 582: file_key = key_new(host_key->type);
1.38 markus 583:
1.40 markus 584: /*
1.170 djm 585: * Check if the host key is present in the user's list of known
1.40 markus 586: * hosts or in the systemwide list.
587: */
1.85 markus 588: host_file = user_hostfile;
1.108 markus 589: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 590: file_key, &host_line);
1.85 markus 591: if (host_status == HOST_NEW) {
592: host_file = system_hostfile;
1.108 markus 593: host_status = check_host_in_hostfile(host_file, host, host_key,
594: file_key, &host_line);
1.85 markus 595: }
1.40 markus 596: /*
597: * Also perform check for the ip address, skip the check if we are
598: * localhost or the hostname was an ip address to begin with
599: */
1.88 markus 600: if (options.check_host_ip) {
1.58 markus 601: Key *ip_key = key_new(host_key->type);
1.38 markus 602:
1.85 markus 603: ip_file = user_hostfile;
1.108 markus 604: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
605: ip_key, &ip_line);
1.85 markus 606: if (ip_status == HOST_NEW) {
607: ip_file = system_hostfile;
1.108 markus 608: ip_status = check_host_in_hostfile(ip_file, ip,
609: host_key, ip_key, &ip_line);
1.85 markus 610: }
1.38 markus 611: if (host_status == HOST_CHANGED &&
1.58 markus 612: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 613: host_ip_differ = 1;
614:
1.58 markus 615: key_free(ip_key);
1.38 markus 616: } else
617: ip_status = host_status;
618:
1.58 markus 619: key_free(file_key);
1.38 markus 620:
621: switch (host_status) {
622: case HOST_OK:
623: /* The host is known and the key matches. */
1.72 markus 624: debug("Host '%.200s' is known and matches the %s host key.",
625: host, type);
1.85 markus 626: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 627: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 628: if (readonly)
1.138 itojun 629: logit("%s host key for IP address "
1.108 markus 630: "'%.128s' not in list of known hosts.",
631: type, ip);
632: else if (!add_host_to_hostfile(user_hostfile, ip,
1.160 djm 633: host_key, options.hash_known_hosts))
1.138 itojun 634: logit("Failed to add the %s host key for IP "
1.108 markus 635: "address '%.128s' to the list of known "
636: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 637: else
1.138 itojun 638: logit("Warning: Permanently added the %s host "
1.108 markus 639: "key for IP address '%.128s' to the list "
640: "of known hosts.", type, ip);
1.38 markus 641: }
642: break;
643: case HOST_NEW:
1.108 markus 644: if (readonly)
645: goto fail;
1.38 markus 646: /* The host is new. */
647: if (options.strict_host_key_checking == 1) {
1.108 markus 648: /*
649: * User has requested strict host key checking. We
650: * will not add the host key automatically. The only
651: * alternative left is to abort.
652: */
653: error("No %s host key is known for %.200s and you "
654: "have requested strict checking.", type, host);
655: goto fail;
1.38 markus 656: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 657: char msg1[1024], msg2[1024];
658:
659: if (show_other_keys(host, host_key))
660: snprintf(msg1, sizeof(msg1),
1.168 djm 661: "\nbut keys of different type are already"
662: " known for this host.");
1.145 jakob 663: else
664: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 665: /* The default */
1.100 markus 666: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.145 jakob 667: msg2[0] = '\0';
668: if (options.verify_host_key_dns) {
1.153 jakob 669: if (matching_host_key_dns)
1.145 jakob 670: snprintf(msg2, sizeof(msg2),
671: "Matching host key fingerprint"
672: " found in DNS.\n");
673: else
674: snprintf(msg2, sizeof(msg2),
675: "No matching host key fingerprint"
676: " found in DNS.\n");
677: }
1.119 markus 678: snprintf(msg, sizeof(msg),
1.108 markus 679: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 680: "established%s\n"
1.145 jakob 681: "%s key fingerprint is %s.\n%s"
1.108 markus 682: "Are you sure you want to continue connecting "
1.132 markus 683: "(yes/no)? ",
1.145 jakob 684: host, ip, msg1, type, fp, msg2);
1.100 markus 685: xfree(fp);
1.119 markus 686: if (!confirm(msg))
1.108 markus 687: goto fail;
1.38 markus 688: }
1.161 djm 689: /*
690: * If not in strict mode, add the key automatically to the
691: * local known_hosts file.
692: */
1.88 markus 693: if (options.check_host_ip && ip_status == HOST_NEW) {
1.161 djm 694: snprintf(hostline, sizeof(hostline), "%s,%s",
695: host, ip);
1.38 markus 696: hostp = hostline;
1.161 djm 697: if (options.hash_known_hosts) {
698: /* Add hash of host and IP separately */
699: r = add_host_to_hostfile(user_hostfile, host,
700: host_key, options.hash_known_hosts) &&
701: add_host_to_hostfile(user_hostfile, ip,
702: host_key, options.hash_known_hosts);
703: } else {
704: /* Add unhashed "host,ip" */
705: r = add_host_to_hostfile(user_hostfile,
706: hostline, host_key,
707: options.hash_known_hosts);
708: }
709: } else {
710: r = add_host_to_hostfile(user_hostfile, host, host_key,
711: options.hash_known_hosts);
1.38 markus 712: hostp = host;
1.161 djm 713: }
1.38 markus 714:
1.161 djm 715: if (!r)
1.138 itojun 716: logit("Failed to add the host to the list of known "
1.108 markus 717: "hosts (%.500s).", user_hostfile);
1.38 markus 718: else
1.138 itojun 719: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 720: "list of known hosts.", hostp, type);
1.38 markus 721: break;
722: case HOST_CHANGED:
723: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 724: char *key_msg;
1.38 markus 725: if (ip_status == HOST_NEW)
1.158 avsm 726: key_msg = "is unknown";
1.38 markus 727: else if (ip_status == HOST_OK)
1.158 avsm 728: key_msg = "is unchanged";
1.38 markus 729: else
1.158 avsm 730: key_msg = "has a different value";
1.38 markus 731: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
732: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
733: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 734: error("The %s host key for %s has changed,", type, host);
1.38 markus 735: error("and the key for the according IP address %s", ip);
1.158 avsm 736: error("%s. This could either mean that", key_msg);
1.38 markus 737: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 738: error("and its host key have changed at the same time.");
1.88 markus 739: if (ip_status != HOST_NEW)
1.85 markus 740: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 741: }
742: /* The host key has changed. */
1.150 jakob 743: warn_changed_key(host_key);
1.38 markus 744: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 745: user_hostfile);
1.85 markus 746: error("Offending key in %s:%d", host_file, host_line);
1.38 markus 747:
1.40 markus 748: /*
749: * If strict host key checking is in use, the user will have
750: * to edit the key manually and we can only abort.
751: */
1.108 markus 752: if (options.strict_host_key_checking) {
753: error("%s host key for %.200s has changed and you have "
754: "requested strict checking.", type, host);
755: goto fail;
756: }
1.38 markus 757:
1.40 markus 758: /*
759: * If strict host key checking has not been requested, allow
1.144 djm 760: * the connection but without MITM-able authentication or
1.40 markus 761: * agent forwarding.
762: */
1.38 markus 763: if (options.password_authentication) {
1.108 markus 764: error("Password authentication is disabled to avoid "
765: "man-in-the-middle attacks.");
1.38 markus 766: options.password_authentication = 0;
1.144 djm 767: }
768: if (options.kbd_interactive_authentication) {
769: error("Keyboard-interactive authentication is disabled"
770: " to avoid man-in-the-middle attacks.");
771: options.kbd_interactive_authentication = 0;
772: options.challenge_response_authentication = 0;
773: }
774: if (options.challenge_response_authentication) {
775: error("Challenge/response authentication is disabled"
776: " to avoid man-in-the-middle attacks.");
777: options.challenge_response_authentication = 0;
1.38 markus 778: }
779: if (options.forward_agent) {
1.108 markus 780: error("Agent forwarding is disabled to avoid "
781: "man-in-the-middle attacks.");
1.38 markus 782: options.forward_agent = 0;
1.83 markus 783: }
784: if (options.forward_x11) {
1.108 markus 785: error("X11 forwarding is disabled to avoid "
786: "man-in-the-middle attacks.");
1.83 markus 787: options.forward_x11 = 0;
788: }
1.108 markus 789: if (options.num_local_forwards > 0 ||
790: options.num_remote_forwards > 0) {
791: error("Port forwarding is disabled to avoid "
792: "man-in-the-middle attacks.");
793: options.num_local_forwards =
1.118 deraadt 794: options.num_remote_forwards = 0;
1.38 markus 795: }
1.40 markus 796: /*
797: * XXX Should permit the user to change to use the new id.
798: * This could be done by converting the host key to an
799: * identifying sentence, tell that the host identifies itself
800: * by that sentence, and ask the user if he/she whishes to
801: * accept the authentication.
802: */
1.38 markus 803: break;
1.132 markus 804: case HOST_FOUND:
805: fatal("internal error");
806: break;
1.88 markus 807: }
808:
809: if (options.check_host_ip && host_status != HOST_CHANGED &&
810: ip_status == HOST_CHANGED) {
1.119 markus 811: snprintf(msg, sizeof(msg),
812: "Warning: the %s host key for '%.200s' "
813: "differs from the key for the IP address '%.128s'"
814: "\nOffending key for IP in %s:%d",
815: type, host, ip, ip_file, ip_line);
816: if (host_status == HOST_OK) {
817: len = strlen(msg);
818: snprintf(msg + len, sizeof(msg) - len,
819: "\nMatching host key in %s:%d",
1.125 deraadt 820: host_file, host_line);
1.119 markus 821: }
1.88 markus 822: if (options.strict_host_key_checking == 1) {
1.143 djm 823: logit("%s", msg);
1.108 markus 824: error("Exiting, you have requested strict checking.");
825: goto fail;
1.88 markus 826: } else if (options.strict_host_key_checking == 2) {
1.119 markus 827: strlcat(msg, "\nAre you sure you want "
828: "to continue connecting (yes/no)? ", sizeof(msg));
829: if (!confirm(msg))
1.108 markus 830: goto fail;
1.119 markus 831: } else {
1.143 djm 832: logit("%s", msg);
1.88 markus 833: }
1.38 markus 834: }
1.82 provos 835:
836: xfree(ip);
1.108 markus 837: return 0;
838:
839: fail:
840: xfree(ip);
841: return -1;
842: }
843:
1.140 jakob 844: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 845: int
846: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
847: {
848: struct stat st;
1.153 jakob 849: int flags = 0;
1.140 jakob 850:
1.153 jakob 851: if (options.verify_host_key_dns &&
852: verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
853:
854: if (flags & DNS_VERIFY_FOUND) {
855:
856: if (options.verify_host_key_dns == 1 &&
857: flags & DNS_VERIFY_MATCH &&
858: flags & DNS_VERIFY_SECURE)
859: return 0;
860:
861: if (flags & DNS_VERIFY_MATCH) {
862: matching_host_key_dns = 1;
863: } else {
864: warn_changed_key(host_key);
865: error("Update the SSHFP RR in DNS with the new "
866: "host key to get rid of this message.");
867: }
1.140 jakob 868: }
869: }
1.108 markus 870:
871: /* return ok if the key can be found in an old keyfile */
872: if (stat(options.system_hostfile2, &st) == 0 ||
873: stat(options.user_hostfile2, &st) == 0) {
874: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
875: options.user_hostfile2, options.system_hostfile2) == 0)
876: return 0;
877: }
878: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
879: options.user_hostfile, options.system_hostfile);
1.51 markus 880: }
1.70 markus 881:
1.51 markus 882: /*
883: * Starts a dialog with the server, and authenticates the current user on the
884: * server. This does not need any extra privileges. The basic connection
885: * to the server must already have been established before this is called.
886: * If login fails, this function prints an error and never returns.
887: * This function does not require super-user privileges.
888: */
889: void
1.120 markus 890: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 891: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 892: {
893: char *host, *cp;
1.70 markus 894: char *server_user, *local_user;
895:
896: local_user = xstrdup(pw->pw_name);
897: server_user = options.user ? options.user : local_user;
1.51 markus 898:
899: /* Convert the user-supplied hostname into all lowercase. */
900: host = xstrdup(orighost);
901: for (cp = host; *cp; cp++)
902: if (isupper(*cp))
1.178 deraadt 903: *cp = (char)tolower(*cp);
1.51 markus 904:
905: /* Exchange protocol version identification strings with the server. */
906: ssh_exchange_identification();
907:
908: /* Put the connection into non-blocking mode. */
909: packet_set_nonblocking();
910:
911: /* key exchange */
912: /* authenticate user */
1.59 markus 913: if (compat20) {
914: ssh_kex2(host, hostaddr);
1.120 markus 915: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 916: } else {
917: ssh_kex(host, hostaddr);
1.120 markus 918: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 919: }
1.182 markus 920: xfree(local_user);
1.97 markus 921: }
922:
923: void
924: ssh_put_password(char *password)
925: {
926: int size;
927: char *padded;
928:
1.99 deraadt 929: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 930: packet_put_cstring(password);
1.99 deraadt 931: return;
932: }
1.97 markus 933: size = roundup(strlen(password) + 1, 32);
1.179 djm 934: padded = xcalloc(1, size);
1.97 markus 935: strlcpy(padded, password, size);
936: packet_put_string(padded, size);
937: memset(padded, 0, size);
938: xfree(padded);
1.132 markus 939: }
940:
941: static int
942: show_key_from_file(const char *file, const char *host, int keytype)
943: {
944: Key *found;
945: char *fp;
946: int line, ret;
947:
948: found = key_new(keytype);
949: if ((ret = lookup_key_in_hostfile_by_type(file, host,
950: keytype, found, &line))) {
951: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 952: logit("WARNING: %s key found for host %s\n"
1.133 markus 953: "in %s:%d\n"
1.132 markus 954: "%s key fingerprint %s.",
955: key_type(found), host, file, line,
956: key_type(found), fp);
957: xfree(fp);
958: }
959: key_free(found);
960: return (ret);
961: }
962:
963: /* print all known host keys for a given host, but skip keys of given type */
964: static int
965: show_other_keys(const char *host, Key *key)
966: {
967: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
968: int i, found = 0;
969:
970: for (i = 0; type[i] != -1; i++) {
971: if (type[i] == key->type)
972: continue;
973: if (type[i] != KEY_RSA1 &&
974: show_key_from_file(options.user_hostfile2, host, type[i])) {
975: found = 1;
976: continue;
977: }
978: if (type[i] != KEY_RSA1 &&
979: show_key_from_file(options.system_hostfile2, host, type[i])) {
980: found = 1;
981: continue;
982: }
983: if (show_key_from_file(options.user_hostfile, host, type[i])) {
984: found = 1;
985: continue;
986: }
987: if (show_key_from_file(options.system_hostfile, host, type[i])) {
988: found = 1;
989: continue;
990: }
991: debug2("no key of type %d for host %s", type[i], host);
992: }
993: return (found);
1.150 jakob 994: }
995:
996: static void
997: warn_changed_key(Key *host_key)
998: {
999: char *fp;
1.151 jakob 1000: const char *type = key_type(host_key);
1.150 jakob 1001:
1002: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1003:
1004: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1005: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1006: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1007: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1008: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1009: error("It is also possible that the %s host key has just been changed.", type);
1010: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1011: type, fp);
1012: error("Please contact your system administrator.");
1013:
1014: xfree(fp);
1.171 reyk 1015: }
1016:
1017: /*
1018: * Execute a local command
1019: */
1020: int
1021: ssh_local_cmd(const char *args)
1022: {
1023: char *shell;
1024: pid_t pid;
1025: int status;
1026:
1027: if (!options.permit_local_command ||
1028: args == NULL || !*args)
1029: return (1);
1030:
1031: if ((shell = getenv("SHELL")) == NULL)
1032: shell = _PATH_BSHELL;
1033:
1034: pid = fork();
1035: if (pid == 0) {
1036: debug3("Executing %s -c \"%s\"", shell, args);
1037: execl(shell, shell, "-c", args, (char *)NULL);
1038: error("Couldn't execute %s -c \"%s\": %s",
1039: shell, args, strerror(errno));
1040: _exit(1);
1041: } else if (pid == -1)
1042: fatal("fork failed: %.100s", strerror(errno));
1043: while (waitpid(pid, &status, 0) == -1)
1044: if (errno != EINTR)
1045: fatal("Couldn't wait for child: %s", strerror(errno));
1046:
1047: if (!WIFEXITED(status))
1048: return (1);
1049:
1050: return (WEXITSTATUS(status));
1.1 deraadt 1051: }
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