blob: d6072b36c65eebf034722674b2b857664df41af8 [file] [log] [blame]
Damien Millerd4a8b7e1999-10-27 13:42:43 +10001/*
Damien Miller95def091999-11-25 00:26:21 +11002 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
Damien Miller95def091999-11-25 00:26:21 +11005 * Code to connect to a remote host, and to perform the client side of the
6 * login (authentication) dialog.
Damien Millere4340be2000-09-16 13:29:08 +11007 *
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".
Damien Miller95def091999-11-25 00:26:21 +110013 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100014
15#include "includes.h"
Damien Miller62cee002000-09-23 17:15:56 +110016RCSID("$OpenBSD: sshconnect.c,v 1.79 2000/09/17 15:52:51 markus Exp $");
Damien Millerd4a8b7e1999-10-27 13:42:43 +100017
Damien Miller1383bd82000-04-06 12:32:37 +100018#include <openssl/bn.h>
Damien Millereba71ba2000-04-29 23:57:08 +100019#include <openssl/dsa.h>
20#include <openssl/rsa.h>
21
Damien Millerd4a8b7e1999-10-27 13:42:43 +100022#include "xmalloc.h"
23#include "rsa.h"
24#include "ssh.h"
Damien Miller1383bd82000-04-06 12:32:37 +100025#include "buffer.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100026#include "packet.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100027#include "uidswap.h"
28#include "compat.h"
Damien Miller6d7b2cd1999-11-12 15:19:27 +110029#include "readconf.h"
Damien Miller450a7a12000-03-26 13:04:51 +100030#include "key.h"
Damien Millereba71ba2000-04-29 23:57:08 +100031#include "sshconnect.h"
Damien Miller450a7a12000-03-26 13:04:51 +100032#include "hostfile.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100033
Damien Millereba71ba2000-04-29 23:57:08 +100034char *client_version_string = NULL;
35char *server_version_string = NULL;
Damien Miller1383bd82000-04-06 12:32:37 +100036
Damien Milleraae6c611999-12-06 11:47:28 +110037extern Options options;
Damien Miller70fb6712000-05-01 20:59:50 +100038#ifdef HAVE___PROGNAME
Damien Miller34132e52000-01-14 15:45:46 +110039extern char *__progname;
Damien Miller70fb6712000-05-01 20:59:50 +100040#else /* HAVE___PROGNAME */
41static const char *__progname = "ssh";
42#endif /* HAVE___PROGNAME */
Damien Milleraae6c611999-12-06 11:47:28 +110043
Damien Miller95def091999-11-25 00:26:21 +110044/*
45 * Connect to the given ssh server using a proxy command.
46 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100047int
Damien Milleraae6c611999-12-06 11:47:28 +110048ssh_proxy_connect(const char *host, u_short port, uid_t original_real_uid,
Damien Millerd4a8b7e1999-10-27 13:42:43 +100049 const char *proxy_command)
50{
Damien Miller95def091999-11-25 00:26:21 +110051 Buffer command;
52 const char *cp;
53 char *command_string;
54 int pin[2], pout[2];
Damien Miller166fca82000-04-20 07:42:21 +100055 pid_t pid;
Damien Miller34132e52000-01-14 15:45:46 +110056 char strport[NI_MAXSERV];
Damien Millerd4a8b7e1999-10-27 13:42:43 +100057
Damien Miller95def091999-11-25 00:26:21 +110058 /* Convert the port number into a string. */
Damien Miller34132e52000-01-14 15:45:46 +110059 snprintf(strport, sizeof strport, "%hu", port);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100060
Damien Miller95def091999-11-25 00:26:21 +110061 /* Build the final command string in the buffer by making the
62 appropriate substitutions to the given proxy command. */
63 buffer_init(&command);
64 for (cp = proxy_command; *cp; cp++) {
65 if (cp[0] == '%' && cp[1] == '%') {
66 buffer_append(&command, "%", 1);
67 cp++;
68 continue;
Damien Millerd4a8b7e1999-10-27 13:42:43 +100069 }
Damien Miller95def091999-11-25 00:26:21 +110070 if (cp[0] == '%' && cp[1] == 'h') {
71 buffer_append(&command, host, strlen(host));
72 cp++;
73 continue;
74 }
75 if (cp[0] == '%' && cp[1] == 'p') {
Damien Miller34132e52000-01-14 15:45:46 +110076 buffer_append(&command, strport, strlen(strport));
Damien Miller95def091999-11-25 00:26:21 +110077 cp++;
78 continue;
79 }
80 buffer_append(&command, cp, 1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100081 }
Damien Miller95def091999-11-25 00:26:21 +110082 buffer_append(&command, "\0", 1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100083
Damien Miller95def091999-11-25 00:26:21 +110084 /* Get the final command string. */
85 command_string = buffer_ptr(&command);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100086
Damien Miller95def091999-11-25 00:26:21 +110087 /* Create pipes for communicating with the proxy. */
88 if (pipe(pin) < 0 || pipe(pout) < 0)
89 fatal("Could not create pipes to communicate with the proxy: %.100s",
90 strerror(errno));
Damien Millerd4a8b7e1999-10-27 13:42:43 +100091
Damien Miller95def091999-11-25 00:26:21 +110092 debug("Executing proxy command: %.500s", command_string);
Damien Millerd4a8b7e1999-10-27 13:42:43 +100093
Damien Miller95def091999-11-25 00:26:21 +110094 /* Fork and execute the proxy command. */
95 if ((pid = fork()) == 0) {
96 char *argv[10];
Damien Millerd4a8b7e1999-10-27 13:42:43 +100097
Damien Miller95def091999-11-25 00:26:21 +110098 /* Child. Permanently give up superuser privileges. */
99 permanently_set_uid(original_real_uid);
100
101 /* Redirect stdin and stdout. */
102 close(pin[1]);
103 if (pin[0] != 0) {
104 if (dup2(pin[0], 0) < 0)
105 perror("dup2 stdin");
106 close(pin[0]);
107 }
108 close(pout[0]);
109 if (dup2(pout[1], 1) < 0)
110 perror("dup2 stdout");
111 /* Cannot be 1 because pin allocated two descriptors. */
112 close(pout[1]);
113
114 /* Stderr is left as it is so that error messages get
115 printed on the user's terminal. */
Damien Miller7b413d22000-07-01 13:24:21 +1000116 argv[0] = _PATH_BSHELL;
Damien Miller95def091999-11-25 00:26:21 +1100117 argv[1] = "-c";
118 argv[2] = command_string;
119 argv[3] = NULL;
120
121 /* Execute the proxy command. Note that we gave up any
122 extra privileges above. */
Damien Miller7b413d22000-07-01 13:24:21 +1000123 execv(_PATH_BSHELL, argv);
124 perror(_PATH_BSHELL);
Damien Miller95def091999-11-25 00:26:21 +1100125 exit(1);
126 }
127 /* Parent. */
128 if (pid < 0)
129 fatal("fork failed: %.100s", strerror(errno));
130
131 /* Close child side of the descriptors. */
132 close(pin[0]);
133 close(pout[1]);
134
135 /* Free the command name. */
136 buffer_free(&command);
137
138 /* Set the connection file descriptors. */
139 packet_set_connection(pout[0], pin[1]);
140
141 return 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000142}
143
Damien Miller95def091999-11-25 00:26:21 +1100144/*
145 * Creates a (possibly privileged) socket for use as the ssh connection.
146 */
147int
Damien Miller34132e52000-01-14 15:45:46 +1100148ssh_create_socket(uid_t original_real_uid, int privileged, int family)
Damien Miller95def091999-11-25 00:26:21 +1100149{
150 int sock;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000151
Damien Miller5428f641999-11-25 11:54:57 +1100152 /*
153 * If we are running as root and want to connect to a privileged
154 * port, bind our own socket to a privileged port.
155 */
Damien Miller95def091999-11-25 00:26:21 +1100156 if (privileged) {
157 int p = IPPORT_RESERVED - 1;
Damien Miller34132e52000-01-14 15:45:46 +1100158 sock = rresvport_af(&p, family);
Damien Miller95def091999-11-25 00:26:21 +1100159 if (sock < 0)
Damien Miller98c7ad62000-03-09 21:27:49 +1100160 error("rresvport: af=%d %.100s", family, strerror(errno));
161 else
162 debug("Allocated local port %d.", p);
Damien Miller95def091999-11-25 00:26:21 +1100163 } else {
Damien Millera34a28b1999-12-14 10:47:15 +1100164 /*
165 * Just create an ordinary socket on arbitrary port. We use
166 * the user's uid to create the socket.
167 */
Damien Miller95def091999-11-25 00:26:21 +1100168 temporarily_use_uid(original_real_uid);
Damien Miller34132e52000-01-14 15:45:46 +1100169 sock = socket(family, SOCK_STREAM, 0);
Damien Miller95def091999-11-25 00:26:21 +1100170 if (sock < 0)
Damien Miller34132e52000-01-14 15:45:46 +1100171 error("socket: %.100s", strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +1100172 restore_uid();
173 }
174 return sock;
175}
176
177/*
Damien Miller34132e52000-01-14 15:45:46 +1100178 * Opens a TCP/IP connection to the remote server on the given host.
179 * The address of the remote host will be returned in hostaddr.
180 * If port is 0, the default port will be used. If anonymous is zero,
Damien Miller95def091999-11-25 00:26:21 +1100181 * a privileged port will be allocated to make the connection.
182 * This requires super-user privileges if anonymous is false.
183 * Connection_attempts specifies the maximum number of tries (one per
184 * second). If proxy_command is non-NULL, it specifies the command (with %h
185 * and %p substituted for host and port, respectively) to use to contact
186 * the daemon.
187 */
188int
Damien Miller34132e52000-01-14 15:45:46 +1100189ssh_connect(const char *host, struct sockaddr_storage * hostaddr,
Damien Milleraae6c611999-12-06 11:47:28 +1100190 u_short port, int connection_attempts,
Damien Miller95def091999-11-25 00:26:21 +1100191 int anonymous, uid_t original_real_uid,
192 const char *proxy_command)
193{
Damien Miller34132e52000-01-14 15:45:46 +1100194 int sock = -1, attempt;
Damien Miller95def091999-11-25 00:26:21 +1100195 struct servent *sp;
Damien Miller34132e52000-01-14 15:45:46 +1100196 struct addrinfo hints, *ai, *aitop;
197 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
198 int gaierr;
Damien Miller95def091999-11-25 00:26:21 +1100199 struct linger linger;
200
Damien Millercaf6dd62000-08-29 11:33:50 +1100201 debug("ssh_connect: getuid %u geteuid %u anon %d",
202 (u_int) getuid(), (u_int) geteuid(), anonymous);
Damien Miller95def091999-11-25 00:26:21 +1100203
204 /* Get default port if port has not been set. */
205 if (port == 0) {
206 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
207 if (sp)
208 port = ntohs(sp->s_port);
209 else
210 port = SSH_DEFAULT_PORT;
211 }
212 /* If a proxy command is given, connect using it. */
213 if (proxy_command != NULL)
214 return ssh_proxy_connect(host, port, original_real_uid, proxy_command);
215
216 /* No proxy command. */
217
Damien Miller34132e52000-01-14 15:45:46 +1100218 memset(&hints, 0, sizeof(hints));
219 hints.ai_family = IPv4or6;
220 hints.ai_socktype = SOCK_STREAM;
221 snprintf(strport, sizeof strport, "%d", port);
222 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
223 fatal("%s: %.100s: %s", __progname, host,
224 gai_strerror(gaierr));
Damien Miller95def091999-11-25 00:26:21 +1100225
Damien Millera34a28b1999-12-14 10:47:15 +1100226 /*
227 * Try to connect several times. On some machines, the first time
228 * will sometimes fail. In general socket code appears to behave
229 * quite magically on many machines.
230 */
Damien Miller95def091999-11-25 00:26:21 +1100231 for (attempt = 0; attempt < connection_attempts; attempt++) {
232 if (attempt > 0)
233 debug("Trying again...");
234
Damien Miller34132e52000-01-14 15:45:46 +1100235 /* Loop through addresses for this host, and try each one in
Damien Miller4af51302000-04-16 11:18:38 +1000236 sequence until the connection succeeds. */
Damien Miller34132e52000-01-14 15:45:46 +1100237 for (ai = aitop; ai; ai = ai->ai_next) {
238 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
239 continue;
240 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
241 ntop, sizeof(ntop), strport, sizeof(strport),
242 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
243 error("ssh_connect: getnameinfo failed");
244 continue;
245 }
246 debug("Connecting to %.200s [%.100s] port %s.",
247 host, ntop, strport);
Damien Miller95def091999-11-25 00:26:21 +1100248
Damien Miller34132e52000-01-14 15:45:46 +1100249 /* Create a socket for connecting. */
Damien Miller4af51302000-04-16 11:18:38 +1000250 sock = ssh_create_socket(original_real_uid,
Damien Millerbac2d8a2000-09-05 16:13:06 +1100251#ifdef HAVE_CYGWIN
252 !anonymous && port < IPPORT_RESERVED,
253#else
Damien Miller34132e52000-01-14 15:45:46 +1100254 !anonymous && geteuid() == 0 && port < IPPORT_RESERVED,
Damien Millerbac2d8a2000-09-05 16:13:06 +1100255#endif
Damien Miller34132e52000-01-14 15:45:46 +1100256 ai->ai_family);
257 if (sock < 0)
258 continue;
Damien Miller95def091999-11-25 00:26:21 +1100259
Damien Miller34132e52000-01-14 15:45:46 +1100260 /* Connect to the host. We use the user's uid in the
261 * hope that it will help with tcp_wrappers showing
262 * the remote uid as root.
Damien Miller5428f641999-11-25 11:54:57 +1100263 */
Damien Miller95def091999-11-25 00:26:21 +1100264 temporarily_use_uid(original_real_uid);
Damien Miller34132e52000-01-14 15:45:46 +1100265 if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
266 /* Successful connection. */
Damien Miller95fe91b2000-05-13 12:31:22 +1000267 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
Damien Miller95def091999-11-25 00:26:21 +1100268 restore_uid();
269 break;
Damien Miller34132e52000-01-14 15:45:46 +1100270 } else {
Damien Miller95def091999-11-25 00:26:21 +1100271 debug("connect: %.100s", strerror(errno));
272 restore_uid();
Damien Miller5428f641999-11-25 11:54:57 +1100273 /*
274 * Close the failed socket; there appear to
275 * be some problems when reusing a socket for
276 * which connect() has already returned an
277 * error.
278 */
Damien Miller95def091999-11-25 00:26:21 +1100279 shutdown(sock, SHUT_RDWR);
280 close(sock);
281 }
Damien Miller95def091999-11-25 00:26:21 +1100282 }
Damien Miller34132e52000-01-14 15:45:46 +1100283 if (ai)
284 break; /* Successful connection. */
Damien Miller95def091999-11-25 00:26:21 +1100285
286 /* Sleep a moment before retrying. */
287 sleep(1);
288 }
Damien Miller34132e52000-01-14 15:45:46 +1100289
290 freeaddrinfo(aitop);
291
Damien Miller95def091999-11-25 00:26:21 +1100292 /* Return failure if we didn't get a successful connection. */
293 if (attempt >= connection_attempts)
294 return 0;
295
296 debug("Connection established.");
297
Damien Miller5428f641999-11-25 11:54:57 +1100298 /*
299 * Set socket options. We would like the socket to disappear as soon
300 * as it has been closed for whatever reason.
301 */
302 /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
Damien Miller95def091999-11-25 00:26:21 +1100303 linger.l_onoff = 1;
304 linger.l_linger = 5;
305 setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *) &linger, sizeof(linger));
306
307 /* Set the connection. */
308 packet_set_connection(sock, sock);
309
310 return 1;
311}
312
Damien Milleraae6c611999-12-06 11:47:28 +1100313/*
Damien Miller95def091999-11-25 00:26:21 +1100314 * Waits for the server identification string, and sends our own
315 * identification string.
316 */
317void
318ssh_exchange_identification()
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000319{
Damien Miller95def091999-11-25 00:26:21 +1100320 char buf[256], remote_version[256]; /* must be same size! */
Damien Miller78928792000-04-12 20:17:38 +1000321 int remote_major, remote_minor, i, mismatch;
Damien Miller95def091999-11-25 00:26:21 +1100322 int connection_in = packet_get_connection_in();
323 int connection_out = packet_get_connection_out();
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000324
Damien Miller95def091999-11-25 00:26:21 +1100325 /* Read other side\'s version identification. */
Damien Millerf6d9e222000-06-18 14:50:44 +1000326 for (;;) {
327 for (i = 0; i < sizeof(buf) - 1; i++) {
328 int len = atomicio(read, connection_in, &buf[i], 1);
329 if (len < 0)
330 fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
331 if (len != 1)
332 fatal("ssh_exchange_identification: Connection closed by remote host");
333 if (buf[i] == '\r') {
334 buf[i] = '\n';
335 buf[i + 1] = 0;
336 continue; /**XXX wait for \n */
337 }
338 if (buf[i] == '\n') {
339 buf[i + 1] = 0;
340 break;
341 }
Damien Miller95def091999-11-25 00:26:21 +1100342 }
Damien Millerf6d9e222000-06-18 14:50:44 +1000343 buf[sizeof(buf) - 1] = 0;
344 if (strncmp(buf, "SSH-", 4) == 0)
Damien Miller95def091999-11-25 00:26:21 +1100345 break;
Damien Millerf6d9e222000-06-18 14:50:44 +1000346 debug("ssh_exchange_identification: %s", buf);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000347 }
Damien Miller1383bd82000-04-06 12:32:37 +1000348 server_version_string = xstrdup(buf);
Damien Miller95def091999-11-25 00:26:21 +1100349
Damien Miller5428f641999-11-25 11:54:57 +1100350 /*
351 * Check that the versions match. In future this might accept
352 * several versions and set appropriate flags to handle them.
353 */
Damien Miller1383bd82000-04-06 12:32:37 +1000354 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
355 &remote_major, &remote_minor, remote_version) != 3)
Damien Miller95def091999-11-25 00:26:21 +1100356 fatal("Bad remote protocol version identification: '%.100s'", buf);
357 debug("Remote protocol version %d.%d, remote software version %.100s",
358 remote_major, remote_minor, remote_version);
359
Damien Miller1383bd82000-04-06 12:32:37 +1000360 compat_datafellows(remote_version);
Damien Miller78928792000-04-12 20:17:38 +1000361 mismatch = 0;
Damien Miller1383bd82000-04-06 12:32:37 +1000362
Damien Miller78928792000-04-12 20:17:38 +1000363 switch(remote_major) {
364 case 1:
365 if (remote_minor == 99 &&
366 (options.protocol & SSH_PROTO_2) &&
367 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
368 enable_compat20();
369 break;
Damien Miller95def091999-11-25 00:26:21 +1100370 }
Damien Miller78928792000-04-12 20:17:38 +1000371 if (!(options.protocol & SSH_PROTO_1)) {
372 mismatch = 1;
373 break;
374 }
375 if (remote_minor < 3) {
376 fatal("Remote machine has too old SSH software version.");
377 } else if (remote_minor == 3) {
378 /* We speak 1.3, too. */
379 enable_compat13();
380 if (options.forward_agent) {
381 log("Agent forwarding disabled for protocol 1.3");
382 options.forward_agent = 0;
383 }
384 }
385 break;
386 case 2:
387 if (options.protocol & SSH_PROTO_2) {
388 enable_compat20();
389 break;
390 }
391 /* FALLTHROUGH */
Damien Miller4af51302000-04-16 11:18:38 +1000392 default:
Damien Miller78928792000-04-12 20:17:38 +1000393 mismatch = 1;
394 break;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000395 }
Damien Miller78928792000-04-12 20:17:38 +1000396 if (mismatch)
Damien Miller95def091999-11-25 00:26:21 +1100397 fatal("Protocol major versions differ: %d vs. %d",
Damien Miller78928792000-04-12 20:17:38 +1000398 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
399 remote_major);
Damien Millereba71ba2000-04-29 23:57:08 +1000400 if (compat20)
401 packet_set_ssh2_format();
Damien Miller95def091999-11-25 00:26:21 +1100402 /* Send our own protocol version identification. */
403 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
Damien Miller78928792000-04-12 20:17:38 +1000404 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
405 compat20 ? PROTOCOL_MINOR_2 : PROTOCOL_MINOR_1,
Damien Miller1383bd82000-04-06 12:32:37 +1000406 SSH_VERSION);
Damien Miller037a0dc1999-12-07 15:38:31 +1100407 if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
Damien Miller95def091999-11-25 00:26:21 +1100408 fatal("write: %.100s", strerror(errno));
Damien Miller1383bd82000-04-06 12:32:37 +1000409 client_version_string = xstrdup(buf);
410 chop(client_version_string);
411 chop(server_version_string);
412 debug("Local version string %.100s", client_version_string);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000413}
414
Damien Miller95def091999-11-25 00:26:21 +1100415int
416read_yes_or_no(const char *prompt, int defval)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000417{
Damien Miller95def091999-11-25 00:26:21 +1100418 char buf[1024];
419 FILE *f;
420 int retval = -1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000421
Damien Miller95def091999-11-25 00:26:21 +1100422 if (isatty(0))
423 f = stdin;
424 else
425 f = fopen("/dev/tty", "rw");
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000426
Damien Miller95def091999-11-25 00:26:21 +1100427 if (f == NULL)
428 return 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000429
Damien Miller95def091999-11-25 00:26:21 +1100430 fflush(stdout);
431
432 while (1) {
433 fprintf(stderr, "%s", prompt);
434 if (fgets(buf, sizeof(buf), f) == NULL) {
435 /* Print a newline (the prompt probably didn\'t have one). */
436 fprintf(stderr, "\n");
437 strlcpy(buf, "no", sizeof buf);
438 }
439 /* Remove newline from response. */
440 if (strchr(buf, '\n'))
441 *strchr(buf, '\n') = 0;
442
443 if (buf[0] == 0)
444 retval = defval;
445 if (strcmp(buf, "yes") == 0)
446 retval = 1;
Damien Miller62cee002000-09-23 17:15:56 +1100447 else if (strcmp(buf, "no") == 0)
Damien Miller95def091999-11-25 00:26:21 +1100448 retval = 0;
Damien Miller62cee002000-09-23 17:15:56 +1100449 else
450 fprintf(stderr, "Please type 'yes' or 'no'.\n");
Damien Miller95def091999-11-25 00:26:21 +1100451
452 if (retval != -1) {
453 if (f != stdin)
454 fclose(f);
455 return retval;
456 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000457 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000458}
459
Damien Miller95def091999-11-25 00:26:21 +1100460/*
Damien Millera34a28b1999-12-14 10:47:15 +1100461 * check whether the supplied host key is valid, return only if ok.
Damien Miller95def091999-11-25 00:26:21 +1100462 */
Damien Millera34a28b1999-12-14 10:47:15 +1100463
Damien Miller95def091999-11-25 00:26:21 +1100464void
Damien Millereba71ba2000-04-29 23:57:08 +1000465check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
466 const char *user_hostfile, const char *system_hostfile)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000467{
Damien Miller450a7a12000-03-26 13:04:51 +1000468 Key *file_key;
Damien Millere247cc42000-05-07 12:03:14 +1000469 char *type = key_type(host_key);
Damien Millera34a28b1999-12-14 10:47:15 +1100470 char *ip = NULL;
Damien Miller95def091999-11-25 00:26:21 +1100471 char hostline[1000], *hostp;
Damien Miller95def091999-11-25 00:26:21 +1100472 HostStatus host_status;
473 HostStatus ip_status;
Damien Miller34132e52000-01-14 15:45:46 +1100474 int local = 0, host_ip_differ = 0;
Damien Millereaf99942000-01-19 13:45:07 +1100475 int salen;
Damien Miller34132e52000-01-14 15:45:46 +1100476 char ntop[NI_MAXHOST];
477
478 /*
479 * Force accepting of the host key for loopback/localhost. The
480 * problem is that if the home directory is NFS-mounted to multiple
481 * machines, localhost will refer to a different machine in each of
482 * them, and the user will get bogus HOST_CHANGED warnings. This
483 * essentially disables host authentication for localhost; however,
484 * this is probably not a real problem.
485 */
Damien Millereba71ba2000-04-29 23:57:08 +1000486 /** hostaddr == 0! */
Damien Miller34132e52000-01-14 15:45:46 +1100487 switch (hostaddr->sa_family) {
488 case AF_INET:
489 local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
Damien Millereaf99942000-01-19 13:45:07 +1100490 salen = sizeof(struct sockaddr_in);
Damien Miller34132e52000-01-14 15:45:46 +1100491 break;
492 case AF_INET6:
493 local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
Damien Millereaf99942000-01-19 13:45:07 +1100494 salen = sizeof(struct sockaddr_in6);
Damien Miller34132e52000-01-14 15:45:46 +1100495 break;
496 default:
497 local = 0;
Damien Millereaf99942000-01-19 13:45:07 +1100498 salen = sizeof(struct sockaddr_storage);
Damien Miller34132e52000-01-14 15:45:46 +1100499 break;
500 }
501 if (local) {
502 debug("Forcing accepting of host key for loopback/localhost.");
503 return;
504 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000505
Damien Milleraae6c611999-12-06 11:47:28 +1100506 /*
507 * Turn off check_host_ip for proxy connects, since
508 * we don't have the remote ip-address
509 */
510 if (options.proxy_command != NULL && options.check_host_ip)
511 options.check_host_ip = 0;
512
Damien Miller34132e52000-01-14 15:45:46 +1100513 if (options.check_host_ip) {
Damien Millereaf99942000-01-19 13:45:07 +1100514 if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
Damien Miller34132e52000-01-14 15:45:46 +1100515 NULL, 0, NI_NUMERICHOST) != 0)
516 fatal("check_host_key: getnameinfo failed");
517 ip = xstrdup(ntop);
518 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000519
Damien Millera34a28b1999-12-14 10:47:15 +1100520 /*
521 * Store the host key from the known host file in here so that we can
522 * compare it with the key for the IP address.
523 */
Damien Miller450a7a12000-03-26 13:04:51 +1000524 file_key = key_new(host_key->type);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000525
Damien Miller5428f641999-11-25 11:54:57 +1100526 /*
527 * Check if the host key is present in the user\'s list of known
528 * hosts or in the systemwide list.
529 */
Damien Millereba71ba2000-04-29 23:57:08 +1000530 host_status = check_host_in_hostfile(user_hostfile, host, host_key, file_key);
Damien Miller95def091999-11-25 00:26:21 +1100531 if (host_status == HOST_NEW)
Damien Millereba71ba2000-04-29 23:57:08 +1000532 host_status = check_host_in_hostfile(system_hostfile, host, host_key, file_key);
Damien Miller5428f641999-11-25 11:54:57 +1100533 /*
Damien Miller5428f641999-11-25 11:54:57 +1100534 * Also perform check for the ip address, skip the check if we are
535 * localhost or the hostname was an ip address to begin with
536 */
Damien Miller95def091999-11-25 00:26:21 +1100537 if (options.check_host_ip && !local && strcmp(host, ip)) {
Damien Miller450a7a12000-03-26 13:04:51 +1000538 Key *ip_key = key_new(host_key->type);
Damien Millereba71ba2000-04-29 23:57:08 +1000539 ip_status = check_host_in_hostfile(user_hostfile, ip, host_key, ip_key);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000540
Damien Miller95def091999-11-25 00:26:21 +1100541 if (ip_status == HOST_NEW)
Damien Millereba71ba2000-04-29 23:57:08 +1000542 ip_status = check_host_in_hostfile(system_hostfile, ip, host_key, ip_key);
Damien Miller95def091999-11-25 00:26:21 +1100543 if (host_status == HOST_CHANGED &&
Damien Miller450a7a12000-03-26 13:04:51 +1000544 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
Damien Miller95def091999-11-25 00:26:21 +1100545 host_ip_differ = 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000546
Damien Miller450a7a12000-03-26 13:04:51 +1000547 key_free(ip_key);
Damien Miller95def091999-11-25 00:26:21 +1100548 } else
549 ip_status = host_status;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000550
Damien Miller450a7a12000-03-26 13:04:51 +1000551 key_free(file_key);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000552
Damien Miller95def091999-11-25 00:26:21 +1100553 switch (host_status) {
554 case HOST_OK:
555 /* The host is known and the key matches. */
Damien Millere247cc42000-05-07 12:03:14 +1000556 debug("Host '%.200s' is known and matches the %s host key.",
557 host, type);
Damien Miller95def091999-11-25 00:26:21 +1100558 if (options.check_host_ip) {
559 if (ip_status == HOST_NEW) {
Damien Millereba71ba2000-04-29 23:57:08 +1000560 if (!add_host_to_hostfile(user_hostfile, ip, host_key))
Damien Millere247cc42000-05-07 12:03:14 +1000561 log("Failed to add the %s host key for IP address '%.30s' to the list of known hosts (%.30s).",
562 type, ip, user_hostfile);
Damien Miller95def091999-11-25 00:26:21 +1100563 else
Damien Millere247cc42000-05-07 12:03:14 +1000564 log("Warning: Permanently added the %s host key for IP address '%.30s' to the list of known hosts.",
565 type, ip);
Damien Miller95def091999-11-25 00:26:21 +1100566 } else if (ip_status != HOST_OK)
Damien Millere247cc42000-05-07 12:03:14 +1000567 log("Warning: the %s host key for '%.200s' differs from the key for the IP address '%.30s'",
568 type, host, ip);
Damien Miller95def091999-11-25 00:26:21 +1100569 }
570 break;
571 case HOST_NEW:
572 /* The host is new. */
573 if (options.strict_host_key_checking == 1) {
574 /* User has requested strict host key checking. We will not add the host key
575 automatically. The only alternative left is to abort. */
Damien Millere247cc42000-05-07 12:03:14 +1000576 fatal("No %s host key is known for %.200s and you have requested strict checking.", type, host);
Damien Miller95def091999-11-25 00:26:21 +1100577 } else if (options.strict_host_key_checking == 2) {
578 /* The default */
579 char prompt[1024];
Damien Miller450a7a12000-03-26 13:04:51 +1000580 char *fp = key_fingerprint(host_key);
Damien Miller95def091999-11-25 00:26:21 +1100581 snprintf(prompt, sizeof(prompt),
Damien Miller037a0dc1999-12-07 15:38:31 +1100582 "The authenticity of host '%.200s' can't be established.\n"
Damien Millere247cc42000-05-07 12:03:14 +1000583 "%s key fingerprint is %s.\n"
Damien Miller037a0dc1999-12-07 15:38:31 +1100584 "Are you sure you want to continue connecting (yes/no)? ",
Damien Millere247cc42000-05-07 12:03:14 +1000585 host, type, fp);
Damien Miller95def091999-11-25 00:26:21 +1100586 if (!read_yes_or_no(prompt, -1))
587 fatal("Aborted by user!\n");
588 }
589 if (options.check_host_ip && ip_status == HOST_NEW && strcmp(host, ip)) {
590 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
591 hostp = hostline;
592 } else
593 hostp = host;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000594
Damien Miller95def091999-11-25 00:26:21 +1100595 /* If not in strict mode, add the key automatically to the local known_hosts file. */
Damien Millereba71ba2000-04-29 23:57:08 +1000596 if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
Damien Miller95def091999-11-25 00:26:21 +1100597 log("Failed to add the host to the list of known hosts (%.500s).",
Damien Millereba71ba2000-04-29 23:57:08 +1000598 user_hostfile);
Damien Miller95def091999-11-25 00:26:21 +1100599 else
Damien Millere247cc42000-05-07 12:03:14 +1000600 log("Warning: Permanently added '%.200s' (%s) to the list of known hosts.",
601 hostp, type);
Damien Miller95def091999-11-25 00:26:21 +1100602 break;
603 case HOST_CHANGED:
604 if (options.check_host_ip && host_ip_differ) {
605 char *msg;
606 if (ip_status == HOST_NEW)
607 msg = "is unknown";
608 else if (ip_status == HOST_OK)
609 msg = "is unchanged";
610 else
611 msg = "has a different value";
612 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
613 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
614 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
Damien Millere247cc42000-05-07 12:03:14 +1000615 error("The %s host key for %s has changed,", type, host);
Damien Miller95def091999-11-25 00:26:21 +1100616 error("and the key for the according IP address %s", ip);
617 error("%s. This could either mean that", msg);
618 error("DNS SPOOFING is happening or the IP address for the host");
619 error("and its host key have changed at the same time");
620 }
621 /* The host key has changed. */
622 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
Damien Millerf039bad1999-12-21 20:57:20 +1100623 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
Damien Miller95def091999-11-25 00:26:21 +1100624 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
625 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
626 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
Damien Millere247cc42000-05-07 12:03:14 +1000627 error("It is also possible that the %s host key has just been changed.", type);
Damien Miller95def091999-11-25 00:26:21 +1100628 error("Please contact your system administrator.");
629 error("Add correct host key in %.100s to get rid of this message.",
Damien Millereba71ba2000-04-29 23:57:08 +1000630 user_hostfile);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000631
Damien Miller5428f641999-11-25 11:54:57 +1100632 /*
633 * If strict host key checking is in use, the user will have
634 * to edit the key manually and we can only abort.
635 */
Damien Miller95def091999-11-25 00:26:21 +1100636 if (options.strict_host_key_checking)
Damien Millere247cc42000-05-07 12:03:14 +1000637 fatal("%s host key for %.200s has changed and you have requested strict checking.", type, host);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000638
Damien Miller5428f641999-11-25 11:54:57 +1100639 /*
640 * If strict host key checking has not been requested, allow
641 * the connection but without password authentication or
642 * agent forwarding.
643 */
Damien Miller95def091999-11-25 00:26:21 +1100644 if (options.password_authentication) {
645 error("Password authentication is disabled to avoid trojan horses.");
646 options.password_authentication = 0;
647 }
648 if (options.forward_agent) {
649 error("Agent forwarding is disabled to avoid trojan horses.");
650 options.forward_agent = 0;
651 }
Damien Miller5428f641999-11-25 11:54:57 +1100652 /*
653 * XXX Should permit the user to change to use the new id.
654 * This could be done by converting the host key to an
655 * identifying sentence, tell that the host identifies itself
656 * by that sentence, and ask the user if he/she whishes to
657 * accept the authentication.
658 */
Damien Miller95def091999-11-25 00:26:21 +1100659 break;
660 }
Damien Miller95def091999-11-25 00:26:21 +1100661 if (options.check_host_ip)
662 xfree(ip);
Damien Millera34a28b1999-12-14 10:47:15 +1100663}
Damien Miller037a0dc1999-12-07 15:38:31 +1100664
Damien Miller396691a2000-01-20 22:44:08 +1100665/*
666 * Starts a dialog with the server, and authenticates the current user on the
667 * server. This does not need any extra privileges. The basic connection
668 * to the server must already have been established before this is called.
669 * If login fails, this function prints an error and never returns.
670 * This function does not require super-user privileges.
671 */
672void
673ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost,
674 struct sockaddr *hostaddr, uid_t original_real_uid)
675{
Damien Millereba71ba2000-04-29 23:57:08 +1000676 struct passwd *pw;
Damien Miller396691a2000-01-20 22:44:08 +1100677 char *host, *cp;
Damien Millereba71ba2000-04-29 23:57:08 +1000678 char *server_user, *local_user;
679
680 /* Get local user name. Use it as server user if no user name was given. */
681 pw = getpwuid(original_real_uid);
682 if (!pw)
Damien Millercaf6dd62000-08-29 11:33:50 +1100683 fatal("User id %u not found from user database.", original_real_uid);
Damien Millereba71ba2000-04-29 23:57:08 +1000684 local_user = xstrdup(pw->pw_name);
685 server_user = options.user ? options.user : local_user;
Damien Miller396691a2000-01-20 22:44:08 +1100686
687 /* Convert the user-supplied hostname into all lowercase. */
688 host = xstrdup(orighost);
689 for (cp = host; *cp; cp++)
690 if (isupper(*cp))
691 *cp = tolower(*cp);
692
693 /* Exchange protocol version identification strings with the server. */
694 ssh_exchange_identification();
695
696 /* Put the connection into non-blocking mode. */
697 packet_set_nonblocking();
698
Damien Miller396691a2000-01-20 22:44:08 +1100699 /* key exchange */
Damien Miller396691a2000-01-20 22:44:08 +1100700 /* authenticate user */
Damien Miller1383bd82000-04-06 12:32:37 +1000701 if (compat20) {
702 ssh_kex2(host, hostaddr);
Damien Millereba71ba2000-04-29 23:57:08 +1000703 ssh_userauth2(server_user, host);
Damien Miller1383bd82000-04-06 12:32:37 +1000704 } else {
Damien Miller1383bd82000-04-06 12:32:37 +1000705 ssh_kex(host, hostaddr);
Damien Millereba71ba2000-04-29 23:57:08 +1000706 ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key);
Damien Miller1383bd82000-04-06 12:32:37 +1000707 }
Damien Miller396691a2000-01-20 22:44:08 +1100708}