blob: 623caed73c7b8d4c6f62331e350866ff864b3135 [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 Miller79438cc2001-02-16 12:34:57 +110016RCSID("$OpenBSD: sshconnect.c,v 1.97 2001/02/15 23:19:59 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
Ben Lindstrom226cfa02001-01-22 05:34:40 +000020#include "ssh.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100021#include "xmalloc.h"
22#include "rsa.h"
Damien Miller1383bd82000-04-06 12:32:37 +100023#include "buffer.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100024#include "packet.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100025#include "uidswap.h"
26#include "compat.h"
Damien Miller450a7a12000-03-26 13:04:51 +100027#include "key.h"
Damien Millereba71ba2000-04-29 23:57:08 +100028#include "sshconnect.h"
Damien Miller450a7a12000-03-26 13:04:51 +100029#include "hostfile.h"
Ben Lindstrom226cfa02001-01-22 05:34:40 +000030#include "log.h"
31#include "readconf.h"
32#include "atomicio.h"
33#include "misc.h"
Damien Millerd4a8b7e1999-10-27 13:42:43 +100034
Damien Millereba71ba2000-04-29 23:57:08 +100035char *client_version_string = NULL;
36char *server_version_string = NULL;
Damien Miller1383bd82000-04-06 12:32:37 +100037
Damien Milleraae6c611999-12-06 11:47:28 +110038extern Options options;
Damien Miller34132e52000-01-14 15:45:46 +110039extern char *__progname;
Damien Milleraae6c611999-12-06 11:47:28 +110040
Ben Lindstrom226cfa02001-01-22 05:34:40 +000041/* AF_UNSPEC or AF_INET or AF_INET6 */
42extern int IPv4or6;
43
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. */
Kevin Stevesfcd5d602001-01-07 11:45:22 +0000123 execv(argv[0], argv);
124 perror(argv[0]);
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 gaierr;
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000195 int on = 1;
196 int sock = -1, attempt;
197 char ntop[NI_MAXHOST], strport[NI_MAXSERV];
198 struct addrinfo hints, *ai, *aitop;
Damien Miller95def091999-11-25 00:26:21 +1100199 struct linger linger;
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000200 struct servent *sp;
Damien Miller95def091999-11-25 00:26:21 +1100201
Damien Millercaf6dd62000-08-29 11:33:50 +1100202 debug("ssh_connect: getuid %u geteuid %u anon %d",
203 (u_int) getuid(), (u_int) geteuid(), anonymous);
Damien Miller95def091999-11-25 00:26:21 +1100204
205 /* Get default port if port has not been set. */
206 if (port == 0) {
207 sp = getservbyname(SSH_SERVICE_NAME, "tcp");
208 if (sp)
209 port = ntohs(sp->s_port);
210 else
211 port = SSH_DEFAULT_PORT;
212 }
213 /* If a proxy command is given, connect using it. */
214 if (proxy_command != NULL)
215 return ssh_proxy_connect(host, port, original_real_uid, proxy_command);
216
217 /* No proxy command. */
218
Damien Miller34132e52000-01-14 15:45:46 +1100219 memset(&hints, 0, sizeof(hints));
220 hints.ai_family = IPv4or6;
221 hints.ai_socktype = SOCK_STREAM;
222 snprintf(strport, sizeof strport, "%d", port);
223 if ((gaierr = getaddrinfo(host, strport, &hints, &aitop)) != 0)
224 fatal("%s: %.100s: %s", __progname, host,
225 gai_strerror(gaierr));
Damien Miller95def091999-11-25 00:26:21 +1100226
Damien Millera34a28b1999-12-14 10:47:15 +1100227 /*
228 * Try to connect several times. On some machines, the first time
229 * will sometimes fail. In general socket code appears to behave
230 * quite magically on many machines.
231 */
Damien Miller95def091999-11-25 00:26:21 +1100232 for (attempt = 0; attempt < connection_attempts; attempt++) {
233 if (attempt > 0)
234 debug("Trying again...");
235
Damien Miller34132e52000-01-14 15:45:46 +1100236 /* Loop through addresses for this host, and try each one in
Damien Miller4af51302000-04-16 11:18:38 +1000237 sequence until the connection succeeds. */
Damien Miller34132e52000-01-14 15:45:46 +1100238 for (ai = aitop; ai; ai = ai->ai_next) {
239 if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
240 continue;
241 if (getnameinfo(ai->ai_addr, ai->ai_addrlen,
242 ntop, sizeof(ntop), strport, sizeof(strport),
243 NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
244 error("ssh_connect: getnameinfo failed");
245 continue;
246 }
247 debug("Connecting to %.200s [%.100s] port %s.",
248 host, ntop, strport);
Damien Miller95def091999-11-25 00:26:21 +1100249
Damien Miller34132e52000-01-14 15:45:46 +1100250 /* Create a socket for connecting. */
Damien Miller4af51302000-04-16 11:18:38 +1000251 sock = ssh_create_socket(original_real_uid,
Damien Millerbac2d8a2000-09-05 16:13:06 +1100252#ifdef HAVE_CYGWIN
Damien Miller0bc1bd82000-11-13 22:57:25 +1100253 !anonymous,
Damien Millerbac2d8a2000-09-05 16:13:06 +1100254#else
Damien Miller0bc1bd82000-11-13 22:57:25 +1100255 !anonymous && geteuid() == 0,
Damien Millerbac2d8a2000-09-05 16:13:06 +1100256#endif
Damien Miller34132e52000-01-14 15:45:46 +1100257 ai->ai_family);
258 if (sock < 0)
259 continue;
Damien Miller95def091999-11-25 00:26:21 +1100260
Damien Miller34132e52000-01-14 15:45:46 +1100261 /* Connect to the host. We use the user's uid in the
262 * hope that it will help with tcp_wrappers showing
263 * the remote uid as root.
Damien Miller5428f641999-11-25 11:54:57 +1100264 */
Damien Miller95def091999-11-25 00:26:21 +1100265 temporarily_use_uid(original_real_uid);
Damien Miller34132e52000-01-14 15:45:46 +1100266 if (connect(sock, ai->ai_addr, ai->ai_addrlen) >= 0) {
267 /* Successful connection. */
Kevin Steves43276862001-02-11 13:56:43 +0000268 memcpy(hostaddr, ai->ai_addr, ai->ai_addrlen);
Damien Miller95def091999-11-25 00:26:21 +1100269 restore_uid();
270 break;
Damien Miller34132e52000-01-14 15:45:46 +1100271 } else {
Damien Miller95def091999-11-25 00:26:21 +1100272 debug("connect: %.100s", strerror(errno));
273 restore_uid();
Damien Miller5428f641999-11-25 11:54:57 +1100274 /*
275 * Close the failed socket; there appear to
276 * be some problems when reusing a socket for
277 * which connect() has already returned an
278 * error.
279 */
Damien Miller95def091999-11-25 00:26:21 +1100280 shutdown(sock, SHUT_RDWR);
281 close(sock);
282 }
Damien Miller95def091999-11-25 00:26:21 +1100283 }
Damien Miller34132e52000-01-14 15:45:46 +1100284 if (ai)
285 break; /* Successful connection. */
Damien Miller95def091999-11-25 00:26:21 +1100286
287 /* Sleep a moment before retrying. */
288 sleep(1);
289 }
Damien Miller34132e52000-01-14 15:45:46 +1100290
291 freeaddrinfo(aitop);
292
Damien Miller95def091999-11-25 00:26:21 +1100293 /* Return failure if we didn't get a successful connection. */
294 if (attempt >= connection_attempts)
295 return 0;
296
297 debug("Connection established.");
298
Damien Miller5428f641999-11-25 11:54:57 +1100299 /*
300 * Set socket options. We would like the socket to disappear as soon
301 * as it has been closed for whatever reason.
302 */
303 /* setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (void *)&on, sizeof(on)); */
Damien Miller95def091999-11-25 00:26:21 +1100304 linger.l_onoff = 1;
305 linger.l_linger = 5;
Ben Lindstrombf555ba2001-01-18 02:04:35 +0000306 setsockopt(sock, SOL_SOCKET, SO_LINGER, (void *)&linger, sizeof(linger));
307
308 /* Set keepalives if requested. */
309 if (options.keepalives &&
310 setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, (void *)&on,
311 sizeof(on)) < 0)
312 error("setsockopt SO_KEEPALIVE: %.100s", strerror(errno));
Damien Miller95def091999-11-25 00:26:21 +1100313
314 /* Set the connection. */
315 packet_set_connection(sock, sock);
316
317 return 1;
318}
319
Damien Milleraae6c611999-12-06 11:47:28 +1100320/*
Damien Miller95def091999-11-25 00:26:21 +1100321 * Waits for the server identification string, and sends our own
322 * identification string.
323 */
324void
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000325ssh_exchange_identification(void)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000326{
Damien Miller95def091999-11-25 00:26:21 +1100327 char buf[256], remote_version[256]; /* must be same size! */
Damien Miller78928792000-04-12 20:17:38 +1000328 int remote_major, remote_minor, i, mismatch;
Damien Miller95def091999-11-25 00:26:21 +1100329 int connection_in = packet_get_connection_in();
330 int connection_out = packet_get_connection_out();
Kevin Stevesef4eea92001-02-05 12:42:17 +0000331 int minor1 = PROTOCOL_MINOR_1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000332
Damien Miller95def091999-11-25 00:26:21 +1100333 /* Read other side\'s version identification. */
Damien Millerf6d9e222000-06-18 14:50:44 +1000334 for (;;) {
335 for (i = 0; i < sizeof(buf) - 1; i++) {
336 int len = atomicio(read, connection_in, &buf[i], 1);
337 if (len < 0)
338 fatal("ssh_exchange_identification: read: %.100s", strerror(errno));
339 if (len != 1)
340 fatal("ssh_exchange_identification: Connection closed by remote host");
341 if (buf[i] == '\r') {
342 buf[i] = '\n';
343 buf[i + 1] = 0;
344 continue; /**XXX wait for \n */
345 }
346 if (buf[i] == '\n') {
347 buf[i + 1] = 0;
348 break;
349 }
Damien Miller95def091999-11-25 00:26:21 +1100350 }
Damien Millerf6d9e222000-06-18 14:50:44 +1000351 buf[sizeof(buf) - 1] = 0;
352 if (strncmp(buf, "SSH-", 4) == 0)
Damien Miller95def091999-11-25 00:26:21 +1100353 break;
Damien Millerf6d9e222000-06-18 14:50:44 +1000354 debug("ssh_exchange_identification: %s", buf);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000355 }
Damien Miller1383bd82000-04-06 12:32:37 +1000356 server_version_string = xstrdup(buf);
Damien Miller95def091999-11-25 00:26:21 +1100357
Damien Miller5428f641999-11-25 11:54:57 +1100358 /*
359 * Check that the versions match. In future this might accept
360 * several versions and set appropriate flags to handle them.
361 */
Damien Miller1383bd82000-04-06 12:32:37 +1000362 if (sscanf(server_version_string, "SSH-%d.%d-%[^\n]\n",
363 &remote_major, &remote_minor, remote_version) != 3)
Damien Miller95def091999-11-25 00:26:21 +1100364 fatal("Bad remote protocol version identification: '%.100s'", buf);
365 debug("Remote protocol version %d.%d, remote software version %.100s",
366 remote_major, remote_minor, remote_version);
367
Damien Miller1383bd82000-04-06 12:32:37 +1000368 compat_datafellows(remote_version);
Damien Miller78928792000-04-12 20:17:38 +1000369 mismatch = 0;
Damien Miller1383bd82000-04-06 12:32:37 +1000370
Damien Miller78928792000-04-12 20:17:38 +1000371 switch(remote_major) {
372 case 1:
373 if (remote_minor == 99 &&
374 (options.protocol & SSH_PROTO_2) &&
375 !(options.protocol & SSH_PROTO_1_PREFERRED)) {
376 enable_compat20();
377 break;
Damien Miller95def091999-11-25 00:26:21 +1100378 }
Damien Miller78928792000-04-12 20:17:38 +1000379 if (!(options.protocol & SSH_PROTO_1)) {
380 mismatch = 1;
381 break;
382 }
383 if (remote_minor < 3) {
384 fatal("Remote machine has too old SSH software version.");
Damien Miller0bc1bd82000-11-13 22:57:25 +1100385 } else if (remote_minor == 3 || remote_minor == 4) {
Damien Miller78928792000-04-12 20:17:38 +1000386 /* We speak 1.3, too. */
387 enable_compat13();
Damien Miller0bc1bd82000-11-13 22:57:25 +1100388 minor1 = 3;
Damien Miller78928792000-04-12 20:17:38 +1000389 if (options.forward_agent) {
390 log("Agent forwarding disabled for protocol 1.3");
391 options.forward_agent = 0;
392 }
393 }
394 break;
395 case 2:
396 if (options.protocol & SSH_PROTO_2) {
397 enable_compat20();
398 break;
399 }
400 /* FALLTHROUGH */
Damien Miller4af51302000-04-16 11:18:38 +1000401 default:
Damien Miller78928792000-04-12 20:17:38 +1000402 mismatch = 1;
403 break;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000404 }
Damien Miller78928792000-04-12 20:17:38 +1000405 if (mismatch)
Damien Miller95def091999-11-25 00:26:21 +1100406 fatal("Protocol major versions differ: %d vs. %d",
Damien Miller78928792000-04-12 20:17:38 +1000407 (options.protocol & SSH_PROTO_2) ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
408 remote_major);
Damien Millereba71ba2000-04-29 23:57:08 +1000409 if (compat20)
410 packet_set_ssh2_format();
Damien Miller95def091999-11-25 00:26:21 +1100411 /* Send our own protocol version identification. */
412 snprintf(buf, sizeof buf, "SSH-%d.%d-%.100s\n",
Damien Miller78928792000-04-12 20:17:38 +1000413 compat20 ? PROTOCOL_MAJOR_2 : PROTOCOL_MAJOR_1,
Damien Miller0bc1bd82000-11-13 22:57:25 +1100414 compat20 ? PROTOCOL_MINOR_2 : minor1,
Damien Miller1383bd82000-04-06 12:32:37 +1000415 SSH_VERSION);
Damien Miller037a0dc1999-12-07 15:38:31 +1100416 if (atomicio(write, connection_out, buf, strlen(buf)) != strlen(buf))
Damien Miller95def091999-11-25 00:26:21 +1100417 fatal("write: %.100s", strerror(errno));
Damien Miller1383bd82000-04-06 12:32:37 +1000418 client_version_string = xstrdup(buf);
419 chop(client_version_string);
420 chop(server_version_string);
421 debug("Local version string %.100s", client_version_string);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000422}
423
Ben Lindstromb6c06d92001-02-10 23:21:09 +0000424/* defaults to 'no' */
Damien Miller95def091999-11-25 00:26:21 +1100425int
426read_yes_or_no(const char *prompt, int defval)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000427{
Damien Miller95def091999-11-25 00:26:21 +1100428 char buf[1024];
429 FILE *f;
430 int retval = -1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000431
Ben Lindstromb6c06d92001-02-10 23:21:09 +0000432 if (options.batch_mode)
433 return 0;
434
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000435 if (isatty(STDIN_FILENO))
Damien Miller95def091999-11-25 00:26:21 +1100436 f = stdin;
437 else
Ben Lindstrom31ca54a2001-02-09 02:11:24 +0000438 f = fopen(_PATH_TTY, "rw");
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000439
Damien Miller95def091999-11-25 00:26:21 +1100440 if (f == NULL)
441 return 0;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000442
Damien Miller95def091999-11-25 00:26:21 +1100443 fflush(stdout);
444
445 while (1) {
446 fprintf(stderr, "%s", prompt);
447 if (fgets(buf, sizeof(buf), f) == NULL) {
448 /* Print a newline (the prompt probably didn\'t have one). */
449 fprintf(stderr, "\n");
450 strlcpy(buf, "no", sizeof buf);
451 }
452 /* Remove newline from response. */
453 if (strchr(buf, '\n'))
454 *strchr(buf, '\n') = 0;
455
456 if (buf[0] == 0)
457 retval = defval;
458 if (strcmp(buf, "yes") == 0)
459 retval = 1;
Damien Miller62cee002000-09-23 17:15:56 +1100460 else if (strcmp(buf, "no") == 0)
Damien Miller95def091999-11-25 00:26:21 +1100461 retval = 0;
Damien Miller62cee002000-09-23 17:15:56 +1100462 else
463 fprintf(stderr, "Please type 'yes' or 'no'.\n");
Damien Miller95def091999-11-25 00:26:21 +1100464
465 if (retval != -1) {
466 if (f != stdin)
467 fclose(f);
468 return retval;
469 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000470 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000471}
472
Damien Miller95def091999-11-25 00:26:21 +1100473/*
Damien Millera34a28b1999-12-14 10:47:15 +1100474 * check whether the supplied host key is valid, return only if ok.
Damien Miller95def091999-11-25 00:26:21 +1100475 */
Damien Millera34a28b1999-12-14 10:47:15 +1100476
Damien Miller95def091999-11-25 00:26:21 +1100477void
Damien Millereba71ba2000-04-29 23:57:08 +1000478check_host_key(char *host, struct sockaddr *hostaddr, Key *host_key,
479 const char *user_hostfile, const char *system_hostfile)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000480{
Damien Miller450a7a12000-03-26 13:04:51 +1000481 Key *file_key;
Damien Millere247cc42000-05-07 12:03:14 +1000482 char *type = key_type(host_key);
Damien Millera34a28b1999-12-14 10:47:15 +1100483 char *ip = NULL;
Damien Miller95def091999-11-25 00:26:21 +1100484 char hostline[1000], *hostp;
Damien Miller95def091999-11-25 00:26:21 +1100485 HostStatus host_status;
486 HostStatus ip_status;
Damien Miller34132e52000-01-14 15:45:46 +1100487 int local = 0, host_ip_differ = 0;
Damien Millereaf99942000-01-19 13:45:07 +1100488 int salen;
Damien Miller34132e52000-01-14 15:45:46 +1100489 char ntop[NI_MAXHOST];
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000490 int host_line, ip_line;
Ben Lindstrom46c16222000-12-22 01:43:59 +0000491 const char *host_file = NULL, *ip_file = NULL;
Damien Miller34132e52000-01-14 15:45:46 +1100492
493 /*
494 * Force accepting of the host key for loopback/localhost. The
495 * problem is that if the home directory is NFS-mounted to multiple
496 * machines, localhost will refer to a different machine in each of
497 * them, and the user will get bogus HOST_CHANGED warnings. This
498 * essentially disables host authentication for localhost; however,
499 * this is probably not a real problem.
500 */
Damien Millereba71ba2000-04-29 23:57:08 +1000501 /** hostaddr == 0! */
Damien Miller34132e52000-01-14 15:45:46 +1100502 switch (hostaddr->sa_family) {
503 case AF_INET:
504 local = (ntohl(((struct sockaddr_in *)hostaddr)->sin_addr.s_addr) >> 24) == IN_LOOPBACKNET;
Damien Millereaf99942000-01-19 13:45:07 +1100505 salen = sizeof(struct sockaddr_in);
Damien Miller34132e52000-01-14 15:45:46 +1100506 break;
507 case AF_INET6:
508 local = IN6_IS_ADDR_LOOPBACK(&(((struct sockaddr_in6 *)hostaddr)->sin6_addr));
Damien Millereaf99942000-01-19 13:45:07 +1100509 salen = sizeof(struct sockaddr_in6);
Damien Miller34132e52000-01-14 15:45:46 +1100510 break;
511 default:
512 local = 0;
Damien Millereaf99942000-01-19 13:45:07 +1100513 salen = sizeof(struct sockaddr_storage);
Damien Miller34132e52000-01-14 15:45:46 +1100514 break;
515 }
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000516 if (local && options.host_key_alias == NULL) {
517 debug("Forcing accepting of host key for "
518 "loopback/localhost.");
519 return;
Damien Miller34132e52000-01-14 15:45:46 +1100520 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000521
Damien Milleraae6c611999-12-06 11:47:28 +1100522 /*
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000523 * We don't have the remote ip-address for connections
524 * using a proxy command
Damien Milleraae6c611999-12-06 11:47:28 +1100525 */
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000526 if (options.proxy_command == NULL) {
527 if (getnameinfo(hostaddr, salen, ntop, sizeof(ntop),
528 NULL, 0, NI_NUMERICHOST) != 0)
529 fatal("check_host_key: getnameinfo failed");
530 ip = xstrdup(ntop);
531 } else {
532 ip = xstrdup("<no hostip for proxy command>");
533 }
534 /*
535 * Turn off check_host_ip if the connection is to localhost, via proxy
536 * command or if we don't have a hostname to compare with
537 */
538 if (options.check_host_ip &&
539 (local || strcmp(host, ip) == 0 || options.proxy_command != NULL))
Damien Milleraae6c611999-12-06 11:47:28 +1100540 options.check_host_ip = 0;
541
Damien Millera34a28b1999-12-14 10:47:15 +1100542 /*
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000543 * Allow the user to record the key under a different name. This is
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000544 * useful for ssh tunneling over forwarded connections or if you run
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000545 * multiple sshd's on different ports on the same machine.
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000546 */
547 if (options.host_key_alias != NULL) {
548 host = options.host_key_alias;
549 debug("using hostkeyalias: %s", host);
550 }
551
552 /*
Damien Millera34a28b1999-12-14 10:47:15 +1100553 * Store the host key from the known host file in here so that we can
554 * compare it with the key for the IP address.
555 */
Damien Miller450a7a12000-03-26 13:04:51 +1000556 file_key = key_new(host_key->type);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000557
Damien Miller5428f641999-11-25 11:54:57 +1100558 /*
559 * Check if the host key is present in the user\'s list of known
560 * hosts or in the systemwide list.
561 */
Ben Lindstrom46c16222000-12-22 01:43:59 +0000562 host_file = user_hostfile;
563 host_status = check_host_in_hostfile(host_file, host, host_key, file_key, &host_line);
564 if (host_status == HOST_NEW) {
565 host_file = system_hostfile;
566 host_status = check_host_in_hostfile(host_file, host, host_key, file_key, &host_line);
567 }
Damien Miller5428f641999-11-25 11:54:57 +1100568 /*
Damien Miller5428f641999-11-25 11:54:57 +1100569 * Also perform check for the ip address, skip the check if we are
570 * localhost or the hostname was an ip address to begin with
571 */
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000572 if (options.check_host_ip) {
Damien Miller450a7a12000-03-26 13:04:51 +1000573 Key *ip_key = key_new(host_key->type);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000574
Ben Lindstrom46c16222000-12-22 01:43:59 +0000575 ip_file = user_hostfile;
576 ip_status = check_host_in_hostfile(ip_file, ip, host_key, ip_key, &ip_line);
577 if (ip_status == HOST_NEW) {
578 ip_file = system_hostfile;
579 ip_status = check_host_in_hostfile(ip_file, ip, host_key, ip_key, &ip_line);
580 }
Damien Miller95def091999-11-25 00:26:21 +1100581 if (host_status == HOST_CHANGED &&
Damien Miller450a7a12000-03-26 13:04:51 +1000582 (ip_status != HOST_CHANGED || !key_equal(ip_key, file_key)))
Damien Miller95def091999-11-25 00:26:21 +1100583 host_ip_differ = 1;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000584
Damien Miller450a7a12000-03-26 13:04:51 +1000585 key_free(ip_key);
Damien Miller95def091999-11-25 00:26:21 +1100586 } else
587 ip_status = host_status;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000588
Damien Miller450a7a12000-03-26 13:04:51 +1000589 key_free(file_key);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000590
Damien Miller95def091999-11-25 00:26:21 +1100591 switch (host_status) {
592 case HOST_OK:
593 /* The host is known and the key matches. */
Damien Millere247cc42000-05-07 12:03:14 +1000594 debug("Host '%.200s' is known and matches the %s host key.",
595 host, type);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000596 debug("Found key in %s:%d", host_file, host_line);
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000597 if (options.check_host_ip && ip_status == HOST_NEW) {
598 if (!add_host_to_hostfile(user_hostfile, ip, host_key))
Kevin Steves43276862001-02-11 13:56:43 +0000599 log("Failed to add the %s host key for IP address '%.128s' to the list of known hosts (%.30s).",
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000600 type, ip, user_hostfile);
601 else
Kevin Steves43276862001-02-11 13:56:43 +0000602 log("Warning: Permanently added the %s host key for IP address '%.128s' to the list of known hosts.",
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000603 type, ip);
Damien Miller95def091999-11-25 00:26:21 +1100604 }
605 break;
606 case HOST_NEW:
607 /* The host is new. */
608 if (options.strict_host_key_checking == 1) {
609 /* User has requested strict host key checking. We will not add the host key
610 automatically. The only alternative left is to abort. */
Damien Millere247cc42000-05-07 12:03:14 +1000611 fatal("No %s host key is known for %.200s and you have requested strict checking.", type, host);
Damien Miller95def091999-11-25 00:26:21 +1100612 } else if (options.strict_host_key_checking == 2) {
613 /* The default */
614 char prompt[1024];
Damien Miller95def091999-11-25 00:26:21 +1100615 snprintf(prompt, sizeof(prompt),
Ben Lindstromc72745a2000-12-02 19:03:54 +0000616 "The authenticity of host '%.200s (%s)' can't be established.\n"
Damien Millere247cc42000-05-07 12:03:14 +1000617 "%s key fingerprint is %s.\n"
Damien Miller037a0dc1999-12-07 15:38:31 +1100618 "Are you sure you want to continue connecting (yes/no)? ",
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000619 host, ip, type, key_fingerprint(host_key));
Damien Miller95def091999-11-25 00:26:21 +1100620 if (!read_yes_or_no(prompt, -1))
621 fatal("Aborted by user!\n");
622 }
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000623 if (options.check_host_ip && ip_status == HOST_NEW) {
Damien Miller95def091999-11-25 00:26:21 +1100624 snprintf(hostline, sizeof(hostline), "%s,%s", host, ip);
625 hostp = hostline;
626 } else
627 hostp = host;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000628
Damien Miller95def091999-11-25 00:26:21 +1100629 /* If not in strict mode, add the key automatically to the local known_hosts file. */
Damien Millereba71ba2000-04-29 23:57:08 +1000630 if (!add_host_to_hostfile(user_hostfile, hostp, host_key))
Damien Miller95def091999-11-25 00:26:21 +1100631 log("Failed to add the host to the list of known hosts (%.500s).",
Damien Millereba71ba2000-04-29 23:57:08 +1000632 user_hostfile);
Damien Miller95def091999-11-25 00:26:21 +1100633 else
Damien Millere247cc42000-05-07 12:03:14 +1000634 log("Warning: Permanently added '%.200s' (%s) to the list of known hosts.",
635 hostp, type);
Damien Miller95def091999-11-25 00:26:21 +1100636 break;
637 case HOST_CHANGED:
638 if (options.check_host_ip && host_ip_differ) {
639 char *msg;
640 if (ip_status == HOST_NEW)
641 msg = "is unknown";
642 else if (ip_status == HOST_OK)
643 msg = "is unchanged";
644 else
645 msg = "has a different value";
646 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
647 error("@ WARNING: POSSIBLE DNS SPOOFING DETECTED! @");
648 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
Damien Millere247cc42000-05-07 12:03:14 +1000649 error("The %s host key for %s has changed,", type, host);
Damien Miller95def091999-11-25 00:26:21 +1100650 error("and the key for the according IP address %s", ip);
651 error("%s. This could either mean that", msg);
652 error("DNS SPOOFING is happening or the IP address for the host");
Ben Lindstrom46c16222000-12-22 01:43:59 +0000653 error("and its host key have changed at the same time.");
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000654 if (ip_status != HOST_NEW)
Ben Lindstrom46c16222000-12-22 01:43:59 +0000655 error("Offending key for IP in %s:%d", ip_file, ip_line);
Damien Miller95def091999-11-25 00:26:21 +1100656 }
657 /* The host key has changed. */
658 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
Damien Millerf039bad1999-12-21 20:57:20 +1100659 error("@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @");
Damien Miller95def091999-11-25 00:26:21 +1100660 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
661 error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
662 error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
Damien Millere247cc42000-05-07 12:03:14 +1000663 error("It is also possible that the %s host key has just been changed.", type);
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000664 error("The fingerprint for the %s key sent by the remote host is\n%s.",
665 type, key_fingerprint(host_key));
Damien Miller95def091999-11-25 00:26:21 +1100666 error("Please contact your system administrator.");
667 error("Add correct host key in %.100s to get rid of this message.",
Ben Lindstrom4dccfa52000-12-28 16:40:05 +0000668 user_hostfile);
Ben Lindstrom46c16222000-12-22 01:43:59 +0000669 error("Offending key in %s:%d", host_file, host_line);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000670
Damien Miller5428f641999-11-25 11:54:57 +1100671 /*
672 * If strict host key checking is in use, the user will have
673 * to edit the key manually and we can only abort.
674 */
Damien Miller95def091999-11-25 00:26:21 +1100675 if (options.strict_host_key_checking)
Damien Millere247cc42000-05-07 12:03:14 +1000676 fatal("%s host key for %.200s has changed and you have requested strict checking.", type, host);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000677
Damien Miller5428f641999-11-25 11:54:57 +1100678 /*
679 * If strict host key checking has not been requested, allow
680 * the connection but without password authentication or
681 * agent forwarding.
682 */
Damien Miller95def091999-11-25 00:26:21 +1100683 if (options.password_authentication) {
684 error("Password authentication is disabled to avoid trojan horses.");
685 options.password_authentication = 0;
686 }
687 if (options.forward_agent) {
688 error("Agent forwarding is disabled to avoid trojan horses.");
689 options.forward_agent = 0;
690 }
Ben Lindstromc72745a2000-12-02 19:03:54 +0000691 if (options.forward_x11) {
692 error("X11 forwarding is disabled to avoid trojan horses.");
693 options.forward_x11 = 0;
694 }
Kevin Stevesef4eea92001-02-05 12:42:17 +0000695 if (options.num_local_forwards > 0 || options.num_remote_forwards > 0) {
Ben Lindstromc72745a2000-12-02 19:03:54 +0000696 error("Port forwarding is disabled to avoid trojan horses.");
697 options.num_local_forwards = options.num_remote_forwards = 0;
698 }
Damien Miller5428f641999-11-25 11:54:57 +1100699 /*
700 * XXX Should permit the user to change to use the new id.
701 * This could be done by converting the host key to an
702 * identifying sentence, tell that the host identifies itself
703 * by that sentence, and ask the user if he/she whishes to
704 * accept the authentication.
705 */
Damien Miller95def091999-11-25 00:26:21 +1100706 break;
707 }
Ben Lindstromc72745a2000-12-02 19:03:54 +0000708
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000709 if (options.check_host_ip && host_status != HOST_CHANGED &&
710 ip_status == HOST_CHANGED) {
711 log("Warning: the %s host key for '%.200s' "
Kevin Steves43276862001-02-11 13:56:43 +0000712 "differs from the key for the IP address '%.128s'",
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000713 type, host, ip);
714 if (host_status == HOST_OK)
715 log("Matching host key in %s:%d", host_file, host_line);
716 log("Offending key for IP in %s:%d", ip_file, ip_line);
717 if (options.strict_host_key_checking == 1) {
718 fatal("Exiting, you have requested strict checking.");
719 } else if (options.strict_host_key_checking == 2) {
Damien Miller3c4659c2001-01-31 09:52:43 +1100720 if (!read_yes_or_no("Are you sure you want " \
721 "to continue connecting (yes/no)? ", -1))
Ben Lindstrom5c1fbab2001-01-03 03:51:15 +0000722 fatal("Aborted by user!\n");
723 }
724 }
725
Ben Lindstromc72745a2000-12-02 19:03:54 +0000726 xfree(ip);
Damien Millera34a28b1999-12-14 10:47:15 +1100727}
Damien Miller037a0dc1999-12-07 15:38:31 +1100728
Damien Miller396691a2000-01-20 22:44:08 +1100729/*
730 * Starts a dialog with the server, and authenticates the current user on the
731 * server. This does not need any extra privileges. The basic connection
732 * to the server must already have been established before this is called.
733 * If login fails, this function prints an error and never returns.
734 * This function does not require super-user privileges.
735 */
736void
737ssh_login(int host_key_valid, RSA *own_host_key, const char *orighost,
738 struct sockaddr *hostaddr, uid_t original_real_uid)
739{
Damien Millereba71ba2000-04-29 23:57:08 +1000740 struct passwd *pw;
Damien Miller396691a2000-01-20 22:44:08 +1100741 char *host, *cp;
Damien Millereba71ba2000-04-29 23:57:08 +1000742 char *server_user, *local_user;
743
744 /* Get local user name. Use it as server user if no user name was given. */
745 pw = getpwuid(original_real_uid);
746 if (!pw)
Damien Millercaf6dd62000-08-29 11:33:50 +1100747 fatal("User id %u not found from user database.", original_real_uid);
Damien Millereba71ba2000-04-29 23:57:08 +1000748 local_user = xstrdup(pw->pw_name);
749 server_user = options.user ? options.user : local_user;
Damien Miller396691a2000-01-20 22:44:08 +1100750
751 /* Convert the user-supplied hostname into all lowercase. */
752 host = xstrdup(orighost);
753 for (cp = host; *cp; cp++)
754 if (isupper(*cp))
755 *cp = tolower(*cp);
756
757 /* Exchange protocol version identification strings with the server. */
758 ssh_exchange_identification();
759
760 /* Put the connection into non-blocking mode. */
761 packet_set_nonblocking();
762
Damien Miller396691a2000-01-20 22:44:08 +1100763 /* key exchange */
Damien Miller396691a2000-01-20 22:44:08 +1100764 /* authenticate user */
Damien Miller1383bd82000-04-06 12:32:37 +1000765 if (compat20) {
766 ssh_kex2(host, hostaddr);
Damien Millereba71ba2000-04-29 23:57:08 +1000767 ssh_userauth2(server_user, host);
Damien Miller1383bd82000-04-06 12:32:37 +1000768 } else {
Damien Miller1383bd82000-04-06 12:32:37 +1000769 ssh_kex(host, hostaddr);
Damien Millereba71ba2000-04-29 23:57:08 +1000770 ssh_userauth(local_user, server_user, host, host_key_valid, own_host_key);
Damien Miller1383bd82000-04-06 12:32:37 +1000771 }
Damien Miller396691a2000-01-20 22:44:08 +1100772}
Damien Miller79438cc2001-02-16 12:34:57 +1100773
774void
775ssh_put_password(char *password)
776{
777 int size;
778 char *padded;
779
780 size = roundup(strlen(password) + 1, 32);
781 padded = xmalloc(size);
782 memset(padded, 0, size);
783 strlcpy(padded, password, size);
784 packet_put_string(padded, size);
785 memset(padded, 0, size);
786 xfree(padded);
787}