Annotation of src/usr.bin/ssh/sshconnect.c, Revision 1.190
1.190 ! stevesk 1: /* $OpenBSD: sshconnect.c,v 1.189 2006/07/10 12:46:51 dtucker 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>
1.187 stevesk 21: #include <sys/socket.h>
22:
23: #include <netinet/in.h>
1.172 stevesk 24:
1.176 stevesk 25: #include <ctype.h>
1.190 ! stevesk 26: #include <errno.h>
1.172 stevesk 27: #include <paths.h>
1.188 stevesk 28: #include <pwd.h>
1.71 markus 29:
1.91 markus 30: #include "ssh.h"
1.1 deraadt 31: #include "xmalloc.h"
32: #include "rsa.h"
1.59 markus 33: #include "buffer.h"
1.1 deraadt 34: #include "packet.h"
35: #include "uidswap.h"
1.21 markus 36: #include "compat.h"
1.58 markus 37: #include "key.h"
1.71 markus 38: #include "sshconnect.h"
1.58 markus 39: #include "hostfile.h"
1.91 markus 40: #include "log.h"
41: #include "readconf.h"
42: #include "atomicio.h"
43: #include "misc.h"
1.140 jakob 44: #include "dns.h"
1.186 stevesk 45: #include "version.h"
1.140 jakob 46:
1.70 markus 47: char *client_version_string = NULL;
48: char *server_version_string = NULL;
1.59 markus 49:
1.169 stevesk 50: static int matching_host_key_dns = 0;
1.145 jakob 51:
1.124 markus 52: /* import */
1.43 markus 53: extern Options options;
1.50 markus 54: extern char *__progname;
1.124 markus 55: extern uid_t original_real_uid;
56: extern uid_t original_effective_uid;
1.135 djm 57: extern pid_t proxy_command_pid;
1.91 markus 58:
1.132 markus 59: static int show_other_keys(const char *, Key *);
1.150 jakob 60: static void warn_changed_key(Key *);
1.132 markus 61:
1.39 deraadt 62: /*
63: * Connect to the given ssh server using a proxy command.
64: */
1.109 itojun 65: static int
1.124 markus 66: ssh_proxy_connect(const char *host, u_short port, const char *proxy_command)
1.1 deraadt 67: {
1.164 djm 68: char *command_string, *tmp;
1.38 markus 69: int pin[2], pout[2];
1.69 deraadt 70: pid_t pid;
1.49 markus 71: char strport[NI_MAXSERV];
1.38 markus 72:
73: /* Convert the port number into a string. */
1.49 markus 74: snprintf(strport, sizeof strport, "%hu", port);
1.38 markus 75:
1.135 djm 76: /*
77: * Build the final command string in the buffer by making the
78: * appropriate substitutions to the given proxy command.
79: *
1.154 djm 80: * Use "exec" to avoid "sh -c" processes on some platforms
1.135 djm 81: * (e.g. Solaris)
82: */
1.179 djm 83: xasprintf(&tmp, "exec %s", proxy_command);
1.164 djm 84: command_string = percent_expand(tmp, "h", host,
85: "p", strport, (char *)NULL);
86: xfree(tmp);
1.38 markus 87:
88: /* Create pipes for communicating with the proxy. */
89: if (pipe(pin) < 0 || pipe(pout) < 0)
90: fatal("Could not create pipes to communicate with the proxy: %.100s",
1.118 deraadt 91: strerror(errno));
1.38 markus 92:
93: debug("Executing proxy command: %.500s", command_string);
94:
95: /* Fork and execute the proxy command. */
96: if ((pid = fork()) == 0) {
97: char *argv[10];
98:
99: /* Child. Permanently give up superuser privileges. */
1.184 markus 100: permanently_drop_suid(original_real_uid);
1.38 markus 101:
102: /* Redirect stdin and stdout. */
103: close(pin[1]);
104: if (pin[0] != 0) {
105: if (dup2(pin[0], 0) < 0)
106: perror("dup2 stdin");
107: close(pin[0]);
108: }
109: close(pout[0]);
110: if (dup2(pout[1], 1) < 0)
111: perror("dup2 stdout");
112: /* Cannot be 1 because pin allocated two descriptors. */
113: close(pout[1]);
114:
115: /* Stderr is left as it is so that error messages get
116: printed on the user's terminal. */
1.89 markus 117: argv[0] = _PATH_BSHELL;
1.38 markus 118: argv[1] = "-c";
119: argv[2] = command_string;
120: argv[3] = NULL;
121:
122: /* Execute the proxy command. Note that we gave up any
123: extra privileges above. */
1.89 markus 124: execv(argv[0], argv);
125: perror(argv[0]);
1.38 markus 126: exit(1);
127: }
128: /* Parent. */
129: if (pid < 0)
130: fatal("fork failed: %.100s", strerror(errno));
1.135 djm 131: else
132: proxy_command_pid = pid; /* save pid to clean up later */
1.38 markus 133:
134: /* Close child side of the descriptors. */
135: close(pin[0]);
136: close(pout[1]);
137:
138: /* Free the command name. */
1.164 djm 139: xfree(command_string);
1.38 markus 140:
141: /* Set the connection file descriptors. */
142: packet_set_connection(pout[0], pin[1]);
1.1 deraadt 143:
1.110 markus 144: /* Indicate OK return */
145: return 0;
1.1 deraadt 146: }
147:
1.39 deraadt 148: /*
149: * Creates a (possibly privileged) socket for use as the ssh connection.
150: */
1.109 itojun 151: static int
1.139 markus 152: ssh_create_socket(int privileged, struct addrinfo *ai)
1.1 deraadt 153: {
1.105 markus 154: int sock, gaierr;
155: struct addrinfo hints, *res;
1.1 deraadt 156:
1.40 markus 157: /*
158: * If we are running as root and want to connect to a privileged
159: * port, bind our own socket to a privileged port.
160: */
1.38 markus 161: if (privileged) {
162: int p = IPPORT_RESERVED - 1;
1.124 markus 163: PRIV_START;
1.139 markus 164: sock = rresvport_af(&p, ai->ai_family);
1.124 markus 165: PRIV_END;
1.38 markus 166: if (sock < 0)
1.139 markus 167: error("rresvport: af=%d %.100s", ai->ai_family,
168: strerror(errno));
1.55 markus 169: else
170: debug("Allocated local port %d.", p);
1.105 markus 171: return sock;
172: }
1.139 markus 173: sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
1.105 markus 174: if (sock < 0)
175: error("socket: %.100s", strerror(errno));
176:
177: /* Bind the socket to an alternative local IP address */
178: if (options.bind_address == NULL)
179: return sock;
180:
181: memset(&hints, 0, sizeof(hints));
1.139 markus 182: hints.ai_family = ai->ai_family;
183: hints.ai_socktype = ai->ai_socktype;
184: hints.ai_protocol = ai->ai_protocol;
1.105 markus 185: hints.ai_flags = AI_PASSIVE;
186: gaierr = getaddrinfo(options.bind_address, "0", &hints, &res);
187: if (gaierr) {
188: error("getaddrinfo: %s: %s", options.bind_address,
189: gai_strerror(gaierr));
190: close(sock);
191: return -1;
192: }
193: if (bind(sock, res->ai_addr, res->ai_addrlen) < 0) {
194: error("bind: %s: %s", options.bind_address, strerror(errno));
195: close(sock);
196: freeaddrinfo(res);
197: return -1;
1.38 markus 198: }
1.105 markus 199: freeaddrinfo(res);
1.38 markus 200: return sock;
1.1 deraadt 201: }
202:
1.141 djm 203: static int
204: timeout_connect(int sockfd, const struct sockaddr *serv_addr,
205: socklen_t addrlen, int timeout)
206: {
207: fd_set *fdset;
208: struct timeval tv;
209: socklen_t optlen;
1.179 djm 210: int optval, rc, result = -1;
1.141 djm 211:
212: if (timeout <= 0)
213: return (connect(sockfd, serv_addr, addrlen));
214:
1.156 djm 215: set_nonblock(sockfd);
1.141 djm 216: rc = connect(sockfd, serv_addr, addrlen);
1.156 djm 217: if (rc == 0) {
218: unset_nonblock(sockfd);
1.141 djm 219: return (0);
1.156 djm 220: }
1.141 djm 221: if (errno != EINPROGRESS)
222: return (-1);
223:
1.179 djm 224: fdset = (fd_set *)xcalloc(howmany(sockfd + 1, NFDBITS),
225: sizeof(fd_mask));
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:
1.181 markus 308: for (attempt = 0; attempt < connection_attempts; attempt++) {
1.38 markus 309: if (attempt > 0)
310: debug("Trying again...");
311:
1.181 markus 312: /*
313: * Loop through addresses for this host, and try each one in
314: * sequence until the connection succeeds.
315: */
1.49 markus 316: for (ai = aitop; ai; ai = ai->ai_next) {
317: if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
318: continue;
319: if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
320: ntop, sizeof(ntop), strport, sizeof(strport),
321: NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
322: error("ssh_connect: getnameinfo failed");
323: continue;
324: }
325: debug("Connecting to %.200s [%.100s] port %s.",
326: host, ntop, strport);
327:
328: /* Create a socket for connecting. */
1.139 markus 329: sock = ssh_create_socket(needpriv, ai);
1.49 markus 330: if (sock < 0)
1.110 markus 331: /* Any error is already output */
1.49 markus 332: continue;
333:
1.141 djm 334: if (timeout_connect(sock, ai->ai_addr, ai->ai_addrlen,
335: options.connection_timeout) >= 0) {
1.49 markus 336: /* Successful connection. */
1.102 markus 337: memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
1.38 markus 338: break;
1.49 markus 339: } else {
1.131 itojun 340: debug("connect to address %s port %s: %s",
341: ntop, strport, strerror(errno));
1.38 markus 342: close(sock);
1.181 markus 343: sock = -1;
1.38 markus 344: }
345: }
1.181 markus 346: if (sock != -1)
1.49 markus 347: break; /* Successful connection. */
1.1 deraadt 348:
1.38 markus 349: /* Sleep a moment before retrying. */
350: sleep(1);
351: }
1.49 markus 352:
353: freeaddrinfo(aitop);
354:
1.38 markus 355: /* Return failure if we didn't get a successful connection. */
1.181 markus 356: if (sock == -1) {
1.159 markus 357: error("ssh: connect to host %s port %s: %s",
1.130 itojun 358: host, strport, strerror(errno));
1.159 markus 359: return (-1);
1.130 itojun 360: }
1.38 markus 361:
362: debug("Connection established.");
1.90 markus 363:
1.155 markus 364: /* Set SO_KEEPALIVE if requested. */
365: if (options.tcp_keep_alive &&
1.90 markus 366: setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
367: sizeof(on)) < 0)
368: error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
1.38 markus 369:
370: /* Set the connection. */
371: packet_set_connection(sock, sock);
1.1 deraadt 372:
1.110 markus 373: return 0;
1.59 markus 374: }
375:
1.43 markus 376: /*
1.39 deraadt 377: * Waits for the server identification string, and sends our own
378: * identification string.
379: */
1.109 itojun 380: static void
1.95 itojun 381: ssh_exchange_identification(void)
1.1 deraadt 382: {
1.38 markus 383: char buf[256], remote_version[256]; /* must be same size! */
1.165 djm 384: int remote_major, remote_minor, mismatch;
1.38 markus 385: int connection_in = packet_get_connection_in();
386: int connection_out = packet_get_connection_out();
1.93 stevesk 387: int minor1 = PROTOCOL_MINOR_1;
1.185 djm 388: u_int i, n;
1.38 markus 389:
1.163 avsm 390: /* Read other side's version identification. */
1.185 djm 391: for (n = 0;;) {
1.75 markus 392: for (i = 0; i < sizeof(buf) - 1; i++) {
1.163 avsm 393: size_t len = atomicio(read, connection_in, &buf[i], 1);
394:
1.167 djm 395: if (len != 1 && errno == EPIPE)
1.163 avsm 396: fatal("ssh_exchange_identification: Connection closed by remote host");
397: else if (len != 1)
1.75 markus 398: fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
399: if (buf[i] == '\r') {
400: buf[i] = '\n';
401: buf[i + 1] = 0;
402: continue; /**XXX wait for \n */
403: }
404: if (buf[i] == '\n') {
405: buf[i + 1] = 0;
406: break;
407: }
1.185 djm 408: if (++n > 65536)
409: fatal("ssh_exchange_identification: No banner received");
1.38 markus 410: }
1.75 markus 411: buf[sizeof(buf) - 1] = 0;
1.76 markus 412: if (strncmp(buf, "SSH-", 4) == 0)
1.38 markus 413: break;
1.75 markus 414: debug("ssh_exchange_identification: %s", buf);
1.38 markus 415: }
1.59 markus 416: server_version_string = xstrdup(buf);
1.38 markus 417:
1.40 markus 418: /*
419: * Check that the versions match. In future this might accept
420: * several versions and set appropriate flags to handle them.
421: */
1.59 markus 422: if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
423: &remote_major, &remote_minor, remote_version) != 3)
1.38 markus 424: fatal("Bad remote protocol version identification: '%.100s'", buf);
425: debug("Remote protocol version %d.%d, remote software version %.100s",
1.118 deraadt 426: remote_major, remote_minor, remote_version);
1.38 markus 427:
1.59 markus 428: compat_datafellows(remote_version);
1.64 markus 429: mismatch = 0;
1.59 markus 430:
1.116 deraadt 431: switch (remote_major) {
1.64 markus 432: case 1:
433: if (remote_minor == 99 &&
434: (options.protocol & SSH_PROTO_2) &&
435: !(options.protocol & SSH_PROTO_1_PREFERRED)) {
436: enable_compat20();
437: break;
438: }
439: if (!(options.protocol & SSH_PROTO_1)) {
440: mismatch = 1;
441: break;
442: }
443: if (remote_minor < 3) {
444: fatal("Remote machine has too old SSH software version.");
1.81 markus 445: } else if (remote_minor == 3 || remote_minor == 4) {
1.64 markus 446: /* We speak 1.3, too. */
447: enable_compat13();
1.81 markus 448: minor1 = 3;
1.64 markus 449: if (options.forward_agent) {
1.138 itojun 450: logit("Agent forwarding disabled for protocol 1.3");
1.64 markus 451: options.forward_agent = 0;
452: }
453: }
454: break;
455: case 2:
456: if (options.protocol & SSH_PROTO_2) {
457: enable_compat20();
458: break;
1.38 markus 459: }
1.64 markus 460: /* FALLTHROUGH */
1.68 markus 461: default:
1.64 markus 462: mismatch = 1;
463: break;
1.38 markus 464: }
1.64 markus 465: if (mismatch)
1.38 markus 466: fatal("Protocol major versions differ: %d vs. %d",
1.64 markus 467: (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
468: remote_major);
1.38 markus 469: /* Send our own protocol version identification. */
470: snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
1.64 markus 471: compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
1.81 markus 472: compat20 ? PROTOCOL_MINOR_2 : minor1,
1.59 markus 473: SSH_VERSION);
1.146 deraadt 474: if (atomicio(vwrite, connection_out, buf, strlen(buf)) != strlen(buf))
1.38 markus 475: fatal("write: %.100s", strerror(errno));
1.59 markus 476: client_version_string = xstrdup(buf);
477: chop(client_version_string);
478: chop(server_version_string);
479: debug("Local version string %.100s", client_version_string);
1.1 deraadt 480: }
481:
1.96 markus 482: /* defaults to 'no' */
1.109 itojun 483: static int
1.112 markus 484: confirm(const char *prompt)
1.1 deraadt 485: {
1.119 markus 486: const char *msg, *again = "Please type 'yes' or 'no': ";
487: char *p;
488: int ret = -1;
1.96 markus 489:
490: if (options.batch_mode)
491: return 0;
1.119 markus 492: for (msg = prompt;;msg = again) {
493: p = read_passphrase(msg, RP_ECHO);
494: if (p == NULL ||
495: (p[0] == '\0') || (p[0] == '\n') ||
496: strncasecmp(p, "no", 2) == 0)
497: ret = 0;
1.127 markus 498: if (p && strncasecmp(p, "yes", 3) == 0)
1.119 markus 499: ret = 1;
500: if (p)
501: xfree(p);
502: if (ret != -1)
503: return ret;
1.1 deraadt 504: }
505: }
506:
1.39 deraadt 507: /*
1.108 markus 508: * check whether the supplied host key is valid, return -1 if the key
509: * is not valid. the user_hostfile will not be updated if 'readonly' is true.
1.39 deraadt 510: */
1.109 itojun 511: static int
1.189 dtucker 512: check_host_key(char *hostname, struct sockaddr *hostaddr, Key *host_key,
1.108 markus 513: int readonly, const char *user_hostfile, const char *system_hostfile)
1.1 deraadt 514: {
1.58 markus 515: Key *file_key;
1.152 jakob 516: const char *type = key_type(host_key);
1.189 dtucker 517: char *ip = NULL, *host = NULL;
1.100 markus 518: char hostline[1000], *hostp, *fp;
1.38 markus 519: HostStatus host_status;
520: HostStatus ip_status;
1.161 djm 521: int r, local = 0, host_ip_differ = 0;
1.49 markus 522: char ntop[NI_MAXHOST];
1.119 markus 523: char msg[1024];
1.145 jakob 524: int len, host_line, ip_line;
1.85 markus 525: const char *host_file = NULL, *ip_file = NULL;
1.49 markus 526:
527: /*
528: * Force accepting of the host key for loopback/localhost. The
529: * problem is that if the home directory is NFS-mounted to multiple
530: * machines, localhost will refer to a different machine in each of
531: * them, and the user will get bogus HOST_CHANGED warnings. This
532: * essentially disables host authentication for localhost; however,
533: * this is probably not a real problem.
534: */
1.70 markus 535: /** hostaddr == 0! */
1.49 markus 536: switch (hostaddr->sa_family) {
537: case AF_INET:
1.108 markus 538: local = (ntohl(((struct sockaddr_in *)hostaddr)->
1.168 djm 539: sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
1.49 markus 540: break;
541: case AF_INET6:
1.108 markus 542: local = IN6_IS_ADDR_LOOPBACK(
543: &(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
1.49 markus 544: break;
545: default:
546: local = 0;
547: break;
548: }
1.111 markus 549: if (options.no_host_authentication_for_localhost == 1 && local &&
550: options.host_key_alias == NULL) {
1.88 markus 551: debug("Forcing accepting of host key for "
552: "loopback/localhost.");
1.108 markus 553: return 0;
1.49 markus 554: }
1.42 markus 555:
556: /*
1.88 markus 557: * We don't have the remote ip-address for connections
558: * using a proxy command
1.42 markus 559: */
1.84 markus 560: if (options.proxy_command == NULL) {
561: if (getnameinfo(hostaddr, hostaddr->sa_len, ntop, sizeof(ntop),
1.86 markus 562: NULL, 0, NI_NUMERICHOST) != 0)
1.84 markus 563: fatal("check_host_key: getnameinfo failed");
1.189 dtucker 564: ip = put_host_port(ntop, options.port);
1.84 markus 565: } else {
566: ip = xstrdup("<no hostip for proxy command>");
1.86 markus 567: }
1.88 markus 568: /*
569: * Turn off check_host_ip if the connection is to localhost, via proxy
570: * command or if we don't have a hostname to compare with
571: */
1.189 dtucker 572: if (options.check_host_ip && (local ||
573: strcmp(hostname, ip) == 0 || options.proxy_command != NULL))
1.88 markus 574: options.check_host_ip = 0;
1.86 markus 575:
576: /*
1.189 dtucker 577: * Allow the user to record the key under a different name or
578: * differentiate a non-standard port. This is useful for ssh
579: * tunneling over forwarded connections or if you run multiple
580: * sshd's on different ports on the same machine.
1.86 markus 581: */
582: if (options.host_key_alias != NULL) {
1.189 dtucker 583: host = xstrdup(options.host_key_alias);
1.86 markus 584: debug("using hostkeyalias: %s", host);
1.189 dtucker 585: } else {
586: host = put_host_port(hostname, options.port);
1.84 markus 587: }
1.38 markus 588:
1.46 markus 589: /*
590: * Store the host key from the known host file in here so that we can
591: * compare it with the key for the IP address.
592: */
1.58 markus 593: file_key = key_new(host_key->type);
1.38 markus 594:
1.40 markus 595: /*
1.170 djm 596: * Check if the host key is present in the user's list of known
1.40 markus 597: * hosts or in the systemwide list.
598: */
1.85 markus 599: host_file = user_hostfile;
1.108 markus 600: host_status = check_host_in_hostfile(host_file, host, host_key,
1.118 deraadt 601: file_key, &host_line);
1.85 markus 602: if (host_status == HOST_NEW) {
603: host_file = system_hostfile;
1.108 markus 604: host_status = check_host_in_hostfile(host_file, host, host_key,
605: file_key, &host_line);
1.85 markus 606: }
1.40 markus 607: /*
608: * Also perform check for the ip address, skip the check if we are
609: * localhost or the hostname was an ip address to begin with
610: */
1.88 markus 611: if (options.check_host_ip) {
1.58 markus 612: Key *ip_key = key_new(host_key->type);
1.38 markus 613:
1.85 markus 614: ip_file = user_hostfile;
1.108 markus 615: ip_status = check_host_in_hostfile(ip_file, ip, host_key,
616: ip_key, &ip_line);
1.85 markus 617: if (ip_status == HOST_NEW) {
618: ip_file = system_hostfile;
1.108 markus 619: ip_status = check_host_in_hostfile(ip_file, ip,
620: host_key, ip_key, &ip_line);
1.85 markus 621: }
1.38 markus 622: if (host_status == HOST_CHANGED &&
1.58 markus 623: (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
1.38 markus 624: host_ip_differ = 1;
625:
1.58 markus 626: key_free(ip_key);
1.38 markus 627: } else
628: ip_status = host_status;
629:
1.58 markus 630: key_free(file_key);
1.38 markus 631:
632: switch (host_status) {
633: case HOST_OK:
634: /* The host is known and the key matches. */
1.72 markus 635: debug("Host '%.200s' is known and matches the %s host key.",
636: host, type);
1.85 markus 637: debug("Found key in %s:%d", host_file, host_line);
1.88 markus 638: if (options.check_host_ip && ip_status == HOST_NEW) {
1.108 markus 639: if (readonly)
1.138 itojun 640: logit("%s host key for IP address "
1.108 markus 641: "'%.128s' not in list of known hosts.",
642: type, ip);
643: else if (!add_host_to_hostfile(user_hostfile, ip,
1.160 djm 644: host_key, options.hash_known_hosts))
1.138 itojun 645: logit("Failed to add the %s host key for IP "
1.108 markus 646: "address '%.128s' to the list of known "
647: "hosts (%.30s).", type, ip, user_hostfile);
1.88 markus 648: else
1.138 itojun 649: logit("Warning: Permanently added the %s host "
1.108 markus 650: "key for IP address '%.128s' to the list "
651: "of known hosts.", type, ip);
1.38 markus 652: }
653: break;
654: case HOST_NEW:
1.108 markus 655: if (readonly)
656: goto fail;
1.38 markus 657: /* The host is new. */
658: if (options.strict_host_key_checking == 1) {
1.108 markus 659: /*
660: * User has requested strict host key checking. We
661: * will not add the host key automatically. The only
662: * alternative left is to abort.
663: */
664: error("No %s host key is known for %.200s and you "
665: "have requested strict checking.", type, host);
666: goto fail;
1.38 markus 667: } else if (options.strict_host_key_checking == 2) {
1.145 jakob 668: char msg1[1024], msg2[1024];
669:
670: if (show_other_keys(host, host_key))
671: snprintf(msg1, sizeof(msg1),
1.168 djm 672: "\nbut keys of different type are already"
673: " known for this host.");
1.145 jakob 674: else
675: snprintf(msg1, sizeof(msg1), ".");
1.38 markus 676: /* The default */
1.100 markus 677: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1.145 jakob 678: msg2[0] = '\0';
679: if (options.verify_host_key_dns) {
1.153 jakob 680: if (matching_host_key_dns)
1.145 jakob 681: snprintf(msg2, sizeof(msg2),
682: "Matching host key fingerprint"
683: " found in DNS.\n");
684: else
685: snprintf(msg2, sizeof(msg2),
686: "No matching host key fingerprint"
687: " found in DNS.\n");
688: }
1.119 markus 689: snprintf(msg, sizeof(msg),
1.108 markus 690: "The authenticity of host '%.200s (%s)' can't be "
1.132 markus 691: "established%s\n"
1.145 jakob 692: "%s key fingerprint is %s.\n%s"
1.108 markus 693: "Are you sure you want to continue connecting "
1.132 markus 694: "(yes/no)? ",
1.145 jakob 695: host, ip, msg1, type, fp, msg2);
1.100 markus 696: xfree(fp);
1.119 markus 697: if (!confirm(msg))
1.108 markus 698: goto fail;
1.38 markus 699: }
1.161 djm 700: /*
701: * If not in strict mode, add the key automatically to the
702: * local known_hosts file.
703: */
1.88 markus 704: if (options.check_host_ip && ip_status == HOST_NEW) {
1.161 djm 705: snprintf(hostline, sizeof(hostline), "%s,%s",
706: host, ip);
1.38 markus 707: hostp = hostline;
1.161 djm 708: if (options.hash_known_hosts) {
709: /* Add hash of host and IP separately */
710: r = add_host_to_hostfile(user_hostfile, host,
711: host_key, options.hash_known_hosts) &&
712: add_host_to_hostfile(user_hostfile, ip,
713: host_key, options.hash_known_hosts);
714: } else {
715: /* Add unhashed "host,ip" */
716: r = add_host_to_hostfile(user_hostfile,
717: hostline, host_key,
718: options.hash_known_hosts);
719: }
720: } else {
721: r = add_host_to_hostfile(user_hostfile, host, host_key,
722: options.hash_known_hosts);
1.38 markus 723: hostp = host;
1.161 djm 724: }
1.38 markus 725:
1.161 djm 726: if (!r)
1.138 itojun 727: logit("Failed to add the host to the list of known "
1.108 markus 728: "hosts (%.500s).", user_hostfile);
1.38 markus 729: else
1.138 itojun 730: logit("Warning: Permanently added '%.200s' (%s) to the "
1.108 markus 731: "list of known hosts.", hostp, type);
1.38 markus 732: break;
733: case HOST_CHANGED:
734: if (options.check_host_ip && host_ip_differ) {
1.158 avsm 735: char *key_msg;
1.38 markus 736: if (ip_status == HOST_NEW)
1.158 avsm 737: key_msg = "is unknown";
1.38 markus 738: else if (ip_status == HOST_OK)
1.158 avsm 739: key_msg = "is unchanged";
1.38 markus 740: else
1.158 avsm 741: key_msg = "has a different value";
1.38 markus 742: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
743: error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
744: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1.72 markus 745: error("The %s host key for %s has changed,", type, host);
1.38 markus 746: error("and the key for the according IP address %s", ip);
1.158 avsm 747: error("%s. This could either mean that", key_msg);
1.38 markus 748: error("DNS SPOOFING is happening or the IP address for the host");
1.85 markus 749: error("and its host key have changed at the same time.");
1.88 markus 750: if (ip_status != HOST_NEW)
1.85 markus 751: error("Offending key for IP in %s:%d", ip_file, ip_line);
1.38 markus 752: }
753: /* The host key has changed. */
1.150 jakob 754: warn_changed_key(host_key);
1.38 markus 755: error("Add correct host key in %.100s to get rid of this message.",
1.87 markus 756: user_hostfile);
1.85 markus 757: error("Offending key in %s:%d", host_file, host_line);
1.38 markus 758:
1.40 markus 759: /*
760: * If strict host key checking is in use, the user will have
761: * to edit the key manually and we can only abort.
762: */
1.108 markus 763: if (options.strict_host_key_checking) {
764: error("%s host key for %.200s has changed and you have "
765: "requested strict checking.", type, host);
766: goto fail;
767: }
1.38 markus 768:
1.40 markus 769: /*
770: * If strict host key checking has not been requested, allow
1.144 djm 771: * the connection but without MITM-able authentication or
1.40 markus 772: * agent forwarding.
773: */
1.38 markus 774: if (options.password_authentication) {
1.108 markus 775: error("Password authentication is disabled to avoid "
776: "man-in-the-middle attacks.");
1.38 markus 777: options.password_authentication = 0;
1.144 djm 778: }
779: if (options.kbd_interactive_authentication) {
780: error("Keyboard-interactive authentication is disabled"
781: " to avoid man-in-the-middle attacks.");
782: options.kbd_interactive_authentication = 0;
783: options.challenge_response_authentication = 0;
784: }
785: if (options.challenge_response_authentication) {
786: error("Challenge/response authentication is disabled"
787: " to avoid man-in-the-middle attacks.");
788: options.challenge_response_authentication = 0;
1.38 markus 789: }
790: if (options.forward_agent) {
1.108 markus 791: error("Agent forwarding is disabled to avoid "
792: "man-in-the-middle attacks.");
1.38 markus 793: options.forward_agent = 0;
1.83 markus 794: }
795: if (options.forward_x11) {
1.108 markus 796: error("X11 forwarding is disabled to avoid "
797: "man-in-the-middle attacks.");
1.83 markus 798: options.forward_x11 = 0;
799: }
1.108 markus 800: if (options.num_local_forwards > 0 ||
801: options.num_remote_forwards > 0) {
802: error("Port forwarding is disabled to avoid "
803: "man-in-the-middle attacks.");
804: options.num_local_forwards =
1.118 deraadt 805: options.num_remote_forwards = 0;
1.38 markus 806: }
1.40 markus 807: /*
808: * XXX Should permit the user to change to use the new id.
809: * This could be done by converting the host key to an
810: * identifying sentence, tell that the host identifies itself
811: * by that sentence, and ask the user if he/she whishes to
812: * accept the authentication.
813: */
1.38 markus 814: break;
1.132 markus 815: case HOST_FOUND:
816: fatal("internal error");
817: break;
1.88 markus 818: }
819:
820: if (options.check_host_ip && host_status != HOST_CHANGED &&
821: ip_status == HOST_CHANGED) {
1.119 markus 822: snprintf(msg, sizeof(msg),
823: "Warning: the %s host key for '%.200s' "
824: "differs from the key for the IP address '%.128s'"
825: "\nOffending key for IP in %s:%d",
826: type, host, ip, ip_file, ip_line);
827: if (host_status == HOST_OK) {
828: len = strlen(msg);
829: snprintf(msg + len, sizeof(msg) - len,
830: "\nMatching host key in %s:%d",
1.125 deraadt 831: host_file, host_line);
1.119 markus 832: }
1.88 markus 833: if (options.strict_host_key_checking == 1) {
1.143 djm 834: logit("%s", msg);
1.108 markus 835: error("Exiting, you have requested strict checking.");
836: goto fail;
1.88 markus 837: } else if (options.strict_host_key_checking == 2) {
1.119 markus 838: strlcat(msg, "\nAre you sure you want "
839: "to continue connecting (yes/no)? ", sizeof(msg));
840: if (!confirm(msg))
1.108 markus 841: goto fail;
1.119 markus 842: } else {
1.143 djm 843: logit("%s", msg);
1.88 markus 844: }
1.38 markus 845: }
1.82 provos 846:
847: xfree(ip);
1.189 dtucker 848: xfree(host);
1.108 markus 849: return 0;
850:
851: fail:
852: xfree(ip);
1.189 dtucker 853: xfree(host);
1.108 markus 854: return -1;
855: }
856:
1.140 jakob 857: /* returns 0 if key verifies or -1 if key does NOT verify */
1.108 markus 858: int
859: verify_host_key(char *host, struct sockaddr *hostaddr, Key *host_key)
860: {
861: struct stat st;
1.153 jakob 862: int flags = 0;
1.140 jakob 863:
1.153 jakob 864: if (options.verify_host_key_dns &&
865: verify_host_key_dns(host, hostaddr, host_key, &flags) == 0) {
866:
867: if (flags & DNS_VERIFY_FOUND) {
868:
869: if (options.verify_host_key_dns == 1 &&
870: flags & DNS_VERIFY_MATCH &&
871: flags & DNS_VERIFY_SECURE)
872: return 0;
873:
874: if (flags & DNS_VERIFY_MATCH) {
875: matching_host_key_dns = 1;
876: } else {
877: warn_changed_key(host_key);
878: error("Update the SSHFP RR in DNS with the new "
879: "host key to get rid of this message.");
880: }
1.140 jakob 881: }
882: }
1.108 markus 883:
884: /* return ok if the key can be found in an old keyfile */
885: if (stat(options.system_hostfile2, &st) == 0 ||
886: stat(options.user_hostfile2, &st) == 0) {
887: if (check_host_key(host, hostaddr, host_key, /*readonly*/ 1,
888: options.user_hostfile2, options.system_hostfile2) == 0)
889: return 0;
890: }
891: return check_host_key(host, hostaddr, host_key, /*readonly*/ 0,
892: options.user_hostfile, options.system_hostfile);
1.51 markus 893: }
1.70 markus 894:
1.51 markus 895: /*
896: * Starts a dialog with the server, and authenticates the current user on the
897: * server. This does not need any extra privileges. The basic connection
898: * to the server must already have been established before this is called.
899: * If login fails, this function prints an error and never returns.
900: * This function does not require super-user privileges.
901: */
902: void
1.120 markus 903: ssh_login(Sensitive *sensitive, const char *orighost,
1.103 markus 904: struct sockaddr *hostaddr, struct passwd *pw)
1.51 markus 905: {
906: char *host, *cp;
1.70 markus 907: char *server_user, *local_user;
908:
909: local_user = xstrdup(pw->pw_name);
910: server_user = options.user ? options.user : local_user;
1.51 markus 911:
912: /* Convert the user-supplied hostname into all lowercase. */
913: host = xstrdup(orighost);
914: for (cp = host; *cp; cp++)
915: if (isupper(*cp))
1.178 deraadt 916: *cp = (char)tolower(*cp);
1.51 markus 917:
918: /* Exchange protocol version identification strings with the server. */
919: ssh_exchange_identification();
920:
921: /* Put the connection into non-blocking mode. */
922: packet_set_nonblocking();
923:
924: /* key exchange */
925: /* authenticate user */
1.59 markus 926: if (compat20) {
927: ssh_kex2(host, hostaddr);
1.120 markus 928: ssh_userauth2(local_user, server_user, host, sensitive);
1.59 markus 929: } else {
930: ssh_kex(host, hostaddr);
1.120 markus 931: ssh_userauth1(local_user, server_user, host, sensitive);
1.59 markus 932: }
1.182 markus 933: xfree(local_user);
1.97 markus 934: }
935:
936: void
937: ssh_put_password(char *password)
938: {
939: int size;
940: char *padded;
941:
1.99 deraadt 942: if (datafellows & SSH_BUG_PASSWORDPAD) {
1.107 markus 943: packet_put_cstring(password);
1.99 deraadt 944: return;
945: }
1.97 markus 946: size = roundup(strlen(password) + 1, 32);
1.179 djm 947: padded = xcalloc(1, size);
1.97 markus 948: strlcpy(padded, password, size);
949: packet_put_string(padded, size);
950: memset(padded, 0, size);
951: xfree(padded);
1.132 markus 952: }
953:
954: static int
955: show_key_from_file(const char *file, const char *host, int keytype)
956: {
957: Key *found;
958: char *fp;
959: int line, ret;
960:
961: found = key_new(keytype);
962: if ((ret = lookup_key_in_hostfile_by_type(file, host,
963: keytype, found, &line))) {
964: fp = key_fingerprint(found, SSH_FP_MD5, SSH_FP_HEX);
1.138 itojun 965: logit("WARNING: %s key found for host %s\n"
1.133 markus 966: "in %s:%d\n"
1.132 markus 967: "%s key fingerprint %s.",
968: key_type(found), host, file, line,
969: key_type(found), fp);
970: xfree(fp);
971: }
972: key_free(found);
973: return (ret);
974: }
975:
976: /* print all known host keys for a given host, but skip keys of given type */
977: static int
978: show_other_keys(const char *host, Key *key)
979: {
980: int type[] = { KEY_RSA1, KEY_RSA, KEY_DSA, -1};
981: int i, found = 0;
982:
983: for (i = 0; type[i] != -1; i++) {
984: if (type[i] == key->type)
985: continue;
986: if (type[i] != KEY_RSA1 &&
987: show_key_from_file(options.user_hostfile2, host, type[i])) {
988: found = 1;
989: continue;
990: }
991: if (type[i] != KEY_RSA1 &&
992: show_key_from_file(options.system_hostfile2, host, type[i])) {
993: found = 1;
994: continue;
995: }
996: if (show_key_from_file(options.user_hostfile, host, type[i])) {
997: found = 1;
998: continue;
999: }
1000: if (show_key_from_file(options.system_hostfile, host, type[i])) {
1001: found = 1;
1002: continue;
1003: }
1004: debug2("no key of type %d for host %s", type[i], host);
1005: }
1006: return (found);
1.150 jakob 1007: }
1008:
1009: static void
1010: warn_changed_key(Key *host_key)
1011: {
1012: char *fp;
1.151 jakob 1013: const char *type = key_type(host_key);
1.150 jakob 1014:
1015: fp = key_fingerprint(host_key, SSH_FP_MD5, SSH_FP_HEX);
1016:
1017: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1018: error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
1019: error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
1020: error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
1021: error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
1022: error("It is also possible that the %s host key has just been changed.", type);
1023: error("The fingerprint for the %s key sent by the remote host is\n%s.",
1024: type, fp);
1025: error("Please contact your system administrator.");
1026:
1027: xfree(fp);
1.171 reyk 1028: }
1029:
1030: /*
1031: * Execute a local command
1032: */
1033: int
1034: ssh_local_cmd(const char *args)
1035: {
1036: char *shell;
1037: pid_t pid;
1038: int status;
1039:
1040: if (!options.permit_local_command ||
1041: args == NULL || !*args)
1042: return (1);
1043:
1044: if ((shell = getenv("SHELL")) == NULL)
1045: shell = _PATH_BSHELL;
1046:
1047: pid = fork();
1048: if (pid == 0) {
1049: debug3("Executing %s -c \"%s\"", shell, args);
1050: execl(shell, shell, "-c", args, (char *)NULL);
1051: error("Couldn't execute %s -c \"%s\": %s",
1052: shell, args, strerror(errno));
1053: _exit(1);
1054: } else if (pid == -1)
1055: fatal("fork failed: %.100s", strerror(errno));
1056: while (waitpid(pid, &status, 0) == -1)
1057: if (errno != EINTR)
1058: fatal("Couldn't wait for child: %s", strerror(errno));
1059:
1060: if (!WIFEXITED(status))
1061: return (1);
1062:
1063: return (WEXITSTATUS(status));
1.1 deraadt 1064: }
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