• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 /* $OpenBSD: clientloop.c,v 1.291 2017/03/10 05:01:13 djm Exp $ */
2 /*
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  * The main loop for the interactive session (client side).
7  *
8  * As far as I am concerned, the code I have written for this software
9  * can be used freely for any purpose.  Any derived versions of this
10  * software must be clearly marked as such, and if the derived work is
11  * incompatible with the protocol description in the RFC file, it must be
12  * called by a name other than "ssh" or "Secure Shell".
13  *
14  *
15  * Copyright (c) 1999 Theo de Raadt.  All rights reserved.
16  *
17  * Redistribution and use in source and binary forms, with or without
18  * modification, are permitted provided that the following conditions
19  * are met:
20  * 1. Redistributions of source code must retain the above copyright
21  *    notice, this list of conditions and the following disclaimer.
22  * 2. Redistributions in binary form must reproduce the above copyright
23  *    notice, this list of conditions and the following disclaimer in the
24  *    documentation and/or other materials provided with the distribution.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36  *
37  *
38  * SSH2 support added by Markus Friedl.
39  * Copyright (c) 1999, 2000, 2001 Markus Friedl.  All rights reserved.
40  *
41  * Redistribution and use in source and binary forms, with or without
42  * modification, are permitted provided that the following conditions
43  * are met:
44  * 1. Redistributions of source code must retain the above copyright
45  *    notice, this list of conditions and the following disclaimer.
46  * 2. Redistributions in binary form must reproduce the above copyright
47  *    notice, this list of conditions and the following disclaimer in the
48  *    documentation and/or other materials provided with the distribution.
49  *
50  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
51  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
52  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
53  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
54  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
55  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
56  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
57  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
58  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
59  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
60  */
61 
62 #include "includes.h"
63 
64 #include <sys/types.h>
65 #include <sys/ioctl.h>
66 #ifdef HAVE_SYS_STAT_H
67 # include <sys/stat.h>
68 #endif
69 #ifdef HAVE_SYS_TIME_H
70 # include <sys/time.h>
71 #endif
72 #include <sys/socket.h>
73 
74 #include <ctype.h>
75 #include <errno.h>
76 #ifdef HAVE_PATHS_H
77 #include <paths.h>
78 #endif
79 #include <signal.h>
80 #include <stdarg.h>
81 #include <stdio.h>
82 #include <stdlib.h>
83 #include <string.h>
84 #include <termios.h>
85 #include <pwd.h>
86 #include <unistd.h>
87 #include <limits.h>
88 
89 #include "openbsd-compat/sys-queue.h"
90 #include "xmalloc.h"
91 #include "ssh.h"
92 #include "ssh1.h"
93 #include "ssh2.h"
94 #include "packet.h"
95 #include "buffer.h"
96 #include "compat.h"
97 #include "channels.h"
98 #include "dispatch.h"
99 #include "key.h"
100 #include "cipher.h"
101 #include "kex.h"
102 #include "myproposal.h"
103 #include "log.h"
104 #include "misc.h"
105 #include "readconf.h"
106 #include "clientloop.h"
107 #include "sshconnect.h"
108 #include "authfd.h"
109 #include "atomicio.h"
110 #include "sshpty.h"
111 #include "match.h"
112 #include "msg.h"
113 #include "ssherr.h"
114 #include "hostfile.h"
115 
116 /* import options */
117 extern Options options;
118 
119 /* Flag indicating that stdin should be redirected from /dev/null. */
120 extern int stdin_null_flag;
121 
122 /* Flag indicating that no shell has been requested */
123 extern int no_shell_flag;
124 
125 /* Flag indicating that ssh should daemonise after authentication is complete */
126 extern int fork_after_authentication_flag;
127 
128 /* Control socket */
129 extern int muxserver_sock; /* XXX use mux_client_cleanup() instead */
130 
131 /*
132  * Name of the host we are connecting to.  This is the name given on the
133  * command line, or the HostName specified for the user-supplied name in a
134  * configuration file.
135  */
136 extern char *host;
137 
138 /*
139  * Flag to indicate that we have received a window change signal which has
140  * not yet been processed.  This will cause a message indicating the new
141  * window size to be sent to the server a little later.  This is volatile
142  * because this is updated in a signal handler.
143  */
144 static volatile sig_atomic_t received_window_change_signal = 0;
145 static volatile sig_atomic_t received_signal = 0;
146 
147 /* Flag indicating whether the user's terminal is in non-blocking mode. */
148 static int in_non_blocking_mode = 0;
149 
150 /* Time when backgrounded control master using ControlPersist should exit */
151 static time_t control_persist_exit_time = 0;
152 
153 /* Common data for the client loop code. */
154 volatile sig_atomic_t quit_pending; /* Set non-zero to quit the loop. */
155 static int escape_char1;	/* Escape character. (proto1 only) */
156 static int escape_pending1;	/* Last character was an escape (proto1 only) */
157 static int last_was_cr;		/* Last character was a newline. */
158 static int exit_status;		/* Used to store the command exit status. */
159 static int stdin_eof;		/* EOF has been encountered on stderr. */
160 static Buffer stdin_buffer;	/* Buffer for stdin data. */
161 static Buffer stdout_buffer;	/* Buffer for stdout data. */
162 static Buffer stderr_buffer;	/* Buffer for stderr data. */
163 static u_int buffer_high;	/* Soft max buffer size. */
164 static int connection_in;	/* Connection to server (input). */
165 static int connection_out;	/* Connection to server (output). */
166 static int need_rekeying;	/* Set to non-zero if rekeying is requested. */
167 static int session_closed;	/* In SSH2: login session closed. */
168 static u_int x11_refuse_time;	/* If >0, refuse x11 opens after this time. */
169 
170 static void client_init_dispatch(void);
171 int	session_ident = -1;
172 
173 /* Track escape per proto2 channel */
174 struct escape_filter_ctx {
175 	int escape_pending;
176 	int escape_char;
177 };
178 
179 /* Context for channel confirmation replies */
180 struct channel_reply_ctx {
181 	const char *request_type;
182 	int id;
183 	enum confirm_action action;
184 };
185 
186 /* Global request success/failure callbacks */
187 struct global_confirm {
188 	TAILQ_ENTRY(global_confirm) entry;
189 	global_confirm_cb *cb;
190 	void *ctx;
191 	int ref_count;
192 };
193 TAILQ_HEAD(global_confirms, global_confirm);
194 static struct global_confirms global_confirms =
195     TAILQ_HEAD_INITIALIZER(global_confirms);
196 
197 void ssh_process_session2_setup(int, int, int, Buffer *);
198 
199 /* Restores stdin to blocking mode. */
200 
201 static void
leave_non_blocking(void)202 leave_non_blocking(void)
203 {
204 	if (in_non_blocking_mode) {
205 		unset_nonblock(fileno(stdin));
206 		in_non_blocking_mode = 0;
207 	}
208 }
209 
210 /* Puts stdin terminal in non-blocking mode. */
211 
212 static void
enter_non_blocking(void)213 enter_non_blocking(void)
214 {
215 	in_non_blocking_mode = 1;
216 	set_nonblock(fileno(stdin));
217 }
218 
219 /*
220  * Signal handler for the window change signal (SIGWINCH).  This just sets a
221  * flag indicating that the window has changed.
222  */
223 /*ARGSUSED */
224 static void
window_change_handler(int sig)225 window_change_handler(int sig)
226 {
227 	received_window_change_signal = 1;
228 	signal(SIGWINCH, window_change_handler);
229 }
230 
231 /*
232  * Signal handler for signals that cause the program to terminate.  These
233  * signals must be trapped to restore terminal modes.
234  */
235 /*ARGSUSED */
236 static void
signal_handler(int sig)237 signal_handler(int sig)
238 {
239 	received_signal = sig;
240 	quit_pending = 1;
241 }
242 
243 /*
244  * Returns current time in seconds from Jan 1, 1970 with the maximum
245  * available resolution.
246  */
247 
248 static double
get_current_time(void)249 get_current_time(void)
250 {
251 	struct timeval tv;
252 	gettimeofday(&tv, NULL);
253 	return (double) tv.tv_sec + (double) tv.tv_usec / 1000000.0;
254 }
255 
256 /*
257  * Sets control_persist_exit_time to the absolute time when the
258  * backgrounded control master should exit due to expiry of the
259  * ControlPersist timeout.  Sets it to 0 if we are not a backgrounded
260  * control master process, or if there is no ControlPersist timeout.
261  */
262 static void
set_control_persist_exit_time(void)263 set_control_persist_exit_time(void)
264 {
265 	if (muxserver_sock == -1 || !options.control_persist
266 	    || options.control_persist_timeout == 0) {
267 		/* not using a ControlPersist timeout */
268 		control_persist_exit_time = 0;
269 	} else if (channel_still_open()) {
270 		/* some client connections are still open */
271 		if (control_persist_exit_time > 0)
272 			debug2("%s: cancel scheduled exit", __func__);
273 		control_persist_exit_time = 0;
274 	} else if (control_persist_exit_time <= 0) {
275 		/* a client connection has recently closed */
276 		control_persist_exit_time = monotime() +
277 			(time_t)options.control_persist_timeout;
278 		debug2("%s: schedule exit in %d seconds", __func__,
279 		    options.control_persist_timeout);
280 	}
281 	/* else we are already counting down to the timeout */
282 }
283 
284 #define SSH_X11_VALID_DISPLAY_CHARS ":/.-_"
285 static int
client_x11_display_valid(const char * display)286 client_x11_display_valid(const char *display)
287 {
288 	size_t i, dlen;
289 
290 	if (display == NULL)
291 		return 0;
292 
293 	dlen = strlen(display);
294 	for (i = 0; i < dlen; i++) {
295 		if (!isalnum((u_char)display[i]) &&
296 		    strchr(SSH_X11_VALID_DISPLAY_CHARS, display[i]) == NULL) {
297 			debug("Invalid character '%c' in DISPLAY", display[i]);
298 			return 0;
299 		}
300 	}
301 	return 1;
302 }
303 
304 #define SSH_X11_PROTO		"MIT-MAGIC-COOKIE-1"
305 #define X11_TIMEOUT_SLACK	60
306 int
client_x11_get_proto(const char * display,const char * xauth_path,u_int trusted,u_int timeout,char ** _proto,char ** _data)307 client_x11_get_proto(const char *display, const char *xauth_path,
308     u_int trusted, u_int timeout, char **_proto, char **_data)
309 {
310 	char cmd[1024], line[512], xdisplay[512];
311 	char xauthfile[PATH_MAX], xauthdir[PATH_MAX];
312 	static char proto[512], data[512];
313 	FILE *f;
314 	int got_data = 0, generated = 0, do_unlink = 0, r;
315 	struct stat st;
316 	u_int now, x11_timeout_real;
317 
318 	*_proto = proto;
319 	*_data = data;
320 	proto[0] = data[0] = xauthfile[0] = xauthdir[0] = '\0';
321 
322 	if (!client_x11_display_valid(display)) {
323 		if (display != NULL)
324 			logit("DISPLAY \"%s\" invalid; disabling X11 forwarding",
325 			    display);
326 		return -1;
327 	}
328 	if (xauth_path != NULL && stat(xauth_path, &st) == -1) {
329 		debug("No xauth program.");
330 		xauth_path = NULL;
331 	}
332 
333 	if (xauth_path != NULL) {
334 		/*
335 		 * Handle FamilyLocal case where $DISPLAY does
336 		 * not match an authorization entry.  For this we
337 		 * just try "xauth list unix:displaynum.screennum".
338 		 * XXX: "localhost" match to determine FamilyLocal
339 		 *      is not perfect.
340 		 */
341 		if (strncmp(display, "localhost:", 10) == 0) {
342 			if ((r = snprintf(xdisplay, sizeof(xdisplay), "unix:%s",
343 			    display + 10)) < 0 ||
344 			    (size_t)r >= sizeof(xdisplay)) {
345 				error("%s: display name too long", __func__);
346 				return -1;
347 			}
348 			display = xdisplay;
349 		}
350 		if (trusted == 0) {
351 			/*
352 			 * Generate an untrusted X11 auth cookie.
353 			 *
354 			 * The authentication cookie should briefly outlive
355 			 * ssh's willingness to forward X11 connections to
356 			 * avoid nasty fail-open behaviour in the X server.
357 			 */
358 			mktemp_proto(xauthdir, sizeof(xauthdir));
359 			if (mkdtemp(xauthdir) == NULL) {
360 				error("%s: mkdtemp: %s",
361 				    __func__, strerror(errno));
362 				return -1;
363 			}
364 			do_unlink = 1;
365 			if ((r = snprintf(xauthfile, sizeof(xauthfile),
366 			    "%s/xauthfile", xauthdir)) < 0 ||
367 			    (size_t)r >= sizeof(xauthfile)) {
368 				error("%s: xauthfile path too long", __func__);
369 				unlink(xauthfile);
370 				rmdir(xauthdir);
371 				return -1;
372 			}
373 
374 			if (timeout >= UINT_MAX - X11_TIMEOUT_SLACK)
375 				x11_timeout_real = UINT_MAX;
376 			else
377 				x11_timeout_real = timeout + X11_TIMEOUT_SLACK;
378 			if ((r = snprintf(cmd, sizeof(cmd),
379 			    "%s -f %s generate %s " SSH_X11_PROTO
380 			    " untrusted timeout %u 2>" _PATH_DEVNULL,
381 			    xauth_path, xauthfile, display,
382 			    x11_timeout_real)) < 0 ||
383 			    (size_t)r >= sizeof(cmd))
384 				fatal("%s: cmd too long", __func__);
385 			debug2("%s: %s", __func__, cmd);
386 			if (x11_refuse_time == 0) {
387 				now = monotime() + 1;
388 				if (UINT_MAX - timeout < now)
389 					x11_refuse_time = UINT_MAX;
390 				else
391 					x11_refuse_time = now + timeout;
392 				channel_set_x11_refuse_time(x11_refuse_time);
393 			}
394 			if (system(cmd) == 0)
395 				generated = 1;
396 		}
397 
398 		/*
399 		 * When in untrusted mode, we read the cookie only if it was
400 		 * successfully generated as an untrusted one in the step
401 		 * above.
402 		 */
403 		if (trusted || generated) {
404 			snprintf(cmd, sizeof(cmd),
405 			    "%s %s%s list %s 2>" _PATH_DEVNULL,
406 			    xauth_path,
407 			    generated ? "-f " : "" ,
408 			    generated ? xauthfile : "",
409 			    display);
410 			debug2("x11_get_proto: %s", cmd);
411 			f = popen(cmd, "r");
412 			if (f && fgets(line, sizeof(line), f) &&
413 			    sscanf(line, "%*s %511s %511s", proto, data) == 2)
414 				got_data = 1;
415 			if (f)
416 				pclose(f);
417 		}
418 	}
419 
420 	if (do_unlink) {
421 		unlink(xauthfile);
422 		rmdir(xauthdir);
423 	}
424 
425 	/* Don't fall back to fake X11 data for untrusted forwarding */
426 	if (!trusted && !got_data) {
427 		error("Warning: untrusted X11 forwarding setup failed: "
428 		    "xauth key data not generated");
429 		return -1;
430 	}
431 
432 	/*
433 	 * If we didn't get authentication data, just make up some
434 	 * data.  The forwarding code will check the validity of the
435 	 * response anyway, and substitute this data.  The X11
436 	 * server, however, will ignore this fake data and use
437 	 * whatever authentication mechanisms it was using otherwise
438 	 * for the local connection.
439 	 */
440 	if (!got_data) {
441 		u_int8_t rnd[16];
442 		u_int i;
443 
444 		logit("Warning: No xauth data; "
445 		    "using fake authentication data for X11 forwarding.");
446 		strlcpy(proto, SSH_X11_PROTO, sizeof proto);
447 		arc4random_buf(rnd, sizeof(rnd));
448 		for (i = 0; i < sizeof(rnd); i++) {
449 			snprintf(data + 2 * i, sizeof data - 2 * i, "%02x",
450 			    rnd[i]);
451 		}
452 	}
453 
454 	return 0;
455 }
456 
457 /*
458  * This is called when the interactive is entered.  This checks if there is
459  * an EOF coming on stdin.  We must check this explicitly, as select() does
460  * not appear to wake up when redirecting from /dev/null.
461  */
462 
463 static void
client_check_initial_eof_on_stdin(void)464 client_check_initial_eof_on_stdin(void)
465 {
466 	int len;
467 	char buf[1];
468 
469 	/*
470 	 * If standard input is to be "redirected from /dev/null", we simply
471 	 * mark that we have seen an EOF and send an EOF message to the
472 	 * server. Otherwise, we try to read a single character; it appears
473 	 * that for some files, such /dev/null, select() never wakes up for
474 	 * read for this descriptor, which means that we never get EOF.  This
475 	 * way we will get the EOF if stdin comes from /dev/null or similar.
476 	 */
477 	if (stdin_null_flag) {
478 		/* Fake EOF on stdin. */
479 		debug("Sending eof.");
480 		stdin_eof = 1;
481 		packet_start(SSH_CMSG_EOF);
482 		packet_send();
483 	} else {
484 		enter_non_blocking();
485 
486 		/* Check for immediate EOF on stdin. */
487 		len = read(fileno(stdin), buf, 1);
488 		if (len == 0) {
489 			/*
490 			 * EOF.  Record that we have seen it and send
491 			 * EOF to server.
492 			 */
493 			debug("Sending eof.");
494 			stdin_eof = 1;
495 			packet_start(SSH_CMSG_EOF);
496 			packet_send();
497 		} else if (len > 0) {
498 			/*
499 			 * Got data.  We must store the data in the buffer,
500 			 * and also process it as an escape character if
501 			 * appropriate.
502 			 */
503 			if ((u_char) buf[0] == escape_char1)
504 				escape_pending1 = 1;
505 			else
506 				buffer_append(&stdin_buffer, buf, 1);
507 		}
508 		leave_non_blocking();
509 	}
510 }
511 
512 
513 /*
514  * Make packets from buffered stdin data, and buffer them for sending to the
515  * connection.
516  */
517 
518 static void
client_make_packets_from_stdin_data(void)519 client_make_packets_from_stdin_data(void)
520 {
521 	u_int len;
522 
523 	/* Send buffered stdin data to the server. */
524 	while (buffer_len(&stdin_buffer) > 0 &&
525 	    packet_not_very_much_data_to_write()) {
526 		len = buffer_len(&stdin_buffer);
527 		/* Keep the packets at reasonable size. */
528 		if (len > packet_get_maxsize())
529 			len = packet_get_maxsize();
530 		packet_start(SSH_CMSG_STDIN_DATA);
531 		packet_put_string(buffer_ptr(&stdin_buffer), len);
532 		packet_send();
533 		buffer_consume(&stdin_buffer, len);
534 		/* If we have a pending EOF, send it now. */
535 		if (stdin_eof && buffer_len(&stdin_buffer) == 0) {
536 			packet_start(SSH_CMSG_EOF);
537 			packet_send();
538 		}
539 	}
540 }
541 
542 /*
543  * Checks if the client window has changed, and sends a packet about it to
544  * the server if so.  The actual change is detected elsewhere (by a software
545  * interrupt on Unix); this just checks the flag and sends a message if
546  * appropriate.
547  */
548 
549 static void
client_check_window_change(void)550 client_check_window_change(void)
551 {
552 	struct winsize ws;
553 
554 	if (! received_window_change_signal)
555 		return;
556 	/** XXX race */
557 	received_window_change_signal = 0;
558 
559 	debug2("client_check_window_change: changed");
560 
561 	if (compat20) {
562 		channel_send_window_changes();
563 	} else {
564 		if (ioctl(fileno(stdin), TIOCGWINSZ, &ws) < 0)
565 			return;
566 		packet_start(SSH_CMSG_WINDOW_SIZE);
567 		packet_put_int((u_int)ws.ws_row);
568 		packet_put_int((u_int)ws.ws_col);
569 		packet_put_int((u_int)ws.ws_xpixel);
570 		packet_put_int((u_int)ws.ws_ypixel);
571 		packet_send();
572 	}
573 }
574 
575 static int
client_global_request_reply(int type,u_int32_t seq,void * ctxt)576 client_global_request_reply(int type, u_int32_t seq, void *ctxt)
577 {
578 	struct global_confirm *gc;
579 
580 	if ((gc = TAILQ_FIRST(&global_confirms)) == NULL)
581 		return 0;
582 	if (gc->cb != NULL)
583 		gc->cb(type, seq, gc->ctx);
584 	if (--gc->ref_count <= 0) {
585 		TAILQ_REMOVE(&global_confirms, gc, entry);
586 		explicit_bzero(gc, sizeof(*gc));
587 		free(gc);
588 	}
589 
590 	packet_set_alive_timeouts(0);
591 	return 0;
592 }
593 
594 static void
server_alive_check(void)595 server_alive_check(void)
596 {
597 	if (packet_inc_alive_timeouts() > options.server_alive_count_max) {
598 		logit("Timeout, server %s not responding.", host);
599 		cleanup_exit(255);
600 	}
601 	packet_start(SSH2_MSG_GLOBAL_REQUEST);
602 	packet_put_cstring("keepalive@openssh.com");
603 	packet_put_char(1);     /* boolean: want reply */
604 	packet_send();
605 	/* Insert an empty placeholder to maintain ordering */
606 	client_register_global_confirm(NULL, NULL);
607 }
608 
609 /*
610  * Waits until the client can do something (some data becomes available on
611  * one of the file descriptors).
612  */
613 static void
client_wait_until_can_do_something(fd_set ** readsetp,fd_set ** writesetp,int * maxfdp,u_int * nallocp,int rekeying)614 client_wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp,
615     int *maxfdp, u_int *nallocp, int rekeying)
616 {
617 	struct timeval tv, *tvp;
618 	int timeout_secs;
619 	time_t minwait_secs = 0, server_alive_time = 0, now = monotime();
620 	int ret;
621 
622 	/* Add any selections by the channel mechanism. */
623 	channel_prepare_select(readsetp, writesetp, maxfdp, nallocp,
624 	    &minwait_secs, rekeying);
625 
626 	if (!compat20) {
627 		/* Read from the connection, unless our buffers are full. */
628 		if (buffer_len(&stdout_buffer) < buffer_high &&
629 		    buffer_len(&stderr_buffer) < buffer_high &&
630 		    channel_not_very_much_buffered_data())
631 			FD_SET(connection_in, *readsetp);
632 		/*
633 		 * Read from stdin, unless we have seen EOF or have very much
634 		 * buffered data to send to the server.
635 		 */
636 		if (!stdin_eof && packet_not_very_much_data_to_write())
637 			FD_SET(fileno(stdin), *readsetp);
638 
639 		/* Select stdout/stderr if have data in buffer. */
640 		if (buffer_len(&stdout_buffer) > 0)
641 			FD_SET(fileno(stdout), *writesetp);
642 		if (buffer_len(&stderr_buffer) > 0)
643 			FD_SET(fileno(stderr), *writesetp);
644 	} else {
645 		/* channel_prepare_select could have closed the last channel */
646 		if (session_closed && !channel_still_open() &&
647 		    !packet_have_data_to_write()) {
648 			/* clear mask since we did not call select() */
649 			memset(*readsetp, 0, *nallocp);
650 			memset(*writesetp, 0, *nallocp);
651 			return;
652 		} else {
653 			FD_SET(connection_in, *readsetp);
654 		}
655 	}
656 
657 	/* Select server connection if have data to write to the server. */
658 	if (packet_have_data_to_write())
659 		FD_SET(connection_out, *writesetp);
660 
661 	/*
662 	 * Wait for something to happen.  This will suspend the process until
663 	 * some selected descriptor can be read, written, or has some other
664 	 * event pending, or a timeout expires.
665 	 */
666 
667 	timeout_secs = INT_MAX; /* we use INT_MAX to mean no timeout */
668 	if (options.server_alive_interval > 0 && compat20) {
669 		timeout_secs = options.server_alive_interval;
670 		server_alive_time = now + options.server_alive_interval;
671 	}
672 	if (options.rekey_interval > 0 && compat20 && !rekeying)
673 		timeout_secs = MINIMUM(timeout_secs, packet_get_rekey_timeout());
674 	set_control_persist_exit_time();
675 	if (control_persist_exit_time > 0) {
676 		timeout_secs = MINIMUM(timeout_secs,
677 			control_persist_exit_time - now);
678 		if (timeout_secs < 0)
679 			timeout_secs = 0;
680 	}
681 	if (minwait_secs != 0)
682 		timeout_secs = MINIMUM(timeout_secs, (int)minwait_secs);
683 	if (timeout_secs == INT_MAX)
684 		tvp = NULL;
685 	else {
686 		tv.tv_sec = timeout_secs;
687 		tv.tv_usec = 0;
688 		tvp = &tv;
689 	}
690 
691 	ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
692 	if (ret < 0) {
693 		char buf[100];
694 
695 		/*
696 		 * We have to clear the select masks, because we return.
697 		 * We have to return, because the mainloop checks for the flags
698 		 * set by the signal handlers.
699 		 */
700 		memset(*readsetp, 0, *nallocp);
701 		memset(*writesetp, 0, *nallocp);
702 
703 		if (errno == EINTR)
704 			return;
705 		/* Note: we might still have data in the buffers. */
706 		snprintf(buf, sizeof buf, "select: %s\r\n", strerror(errno));
707 		buffer_append(&stderr_buffer, buf, strlen(buf));
708 		quit_pending = 1;
709 	} else if (ret == 0) {
710 		/*
711 		 * Timeout.  Could have been either keepalive or rekeying.
712 		 * Keepalive we check here, rekeying is checked in clientloop.
713 		 */
714 		if (server_alive_time != 0 && server_alive_time <= monotime())
715 			server_alive_check();
716 	}
717 
718 }
719 
720 static void
client_suspend_self(Buffer * bin,Buffer * bout,Buffer * berr)721 client_suspend_self(Buffer *bin, Buffer *bout, Buffer *berr)
722 {
723 	/* Flush stdout and stderr buffers. */
724 	if (buffer_len(bout) > 0)
725 		atomicio(vwrite, fileno(stdout), buffer_ptr(bout),
726 		    buffer_len(bout));
727 	if (buffer_len(berr) > 0)
728 		atomicio(vwrite, fileno(stderr), buffer_ptr(berr),
729 		    buffer_len(berr));
730 
731 	leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
732 
733 	/*
734 	 * Free (and clear) the buffer to reduce the amount of data that gets
735 	 * written to swap.
736 	 */
737 	buffer_free(bin);
738 	buffer_free(bout);
739 	buffer_free(berr);
740 
741 	/* Send the suspend signal to the program itself. */
742 	kill(getpid(), SIGTSTP);
743 
744 	/* Reset window sizes in case they have changed */
745 	received_window_change_signal = 1;
746 
747 	/* OK, we have been continued by the user. Reinitialize buffers. */
748 	buffer_init(bin);
749 	buffer_init(bout);
750 	buffer_init(berr);
751 
752 	enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
753 }
754 
755 static void
client_process_net_input(fd_set * readset)756 client_process_net_input(fd_set *readset)
757 {
758 	int len;
759 	char buf[SSH_IOBUFSZ];
760 
761 	/*
762 	 * Read input from the server, and add any such data to the buffer of
763 	 * the packet subsystem.
764 	 */
765 	if (FD_ISSET(connection_in, readset)) {
766 		/* Read as much as possible. */
767 		len = read(connection_in, buf, sizeof(buf));
768 		if (len == 0) {
769 			/*
770 			 * Received EOF.  The remote host has closed the
771 			 * connection.
772 			 */
773 			snprintf(buf, sizeof buf,
774 			    "Connection to %.300s closed by remote host.\r\n",
775 			    host);
776 			buffer_append(&stderr_buffer, buf, strlen(buf));
777 			quit_pending = 1;
778 			return;
779 		}
780 		/*
781 		 * There is a kernel bug on Solaris that causes select to
782 		 * sometimes wake up even though there is no data available.
783 		 */
784 		if (len < 0 &&
785 		    (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK))
786 			len = 0;
787 
788 		if (len < 0) {
789 			/*
790 			 * An error has encountered.  Perhaps there is a
791 			 * network problem.
792 			 */
793 			snprintf(buf, sizeof buf,
794 			    "Read from remote host %.300s: %.100s\r\n",
795 			    host, strerror(errno));
796 			buffer_append(&stderr_buffer, buf, strlen(buf));
797 			quit_pending = 1;
798 			return;
799 		}
800 		packet_process_incoming(buf, len);
801 	}
802 }
803 
804 static void
client_status_confirm(int type,Channel * c,void * ctx)805 client_status_confirm(int type, Channel *c, void *ctx)
806 {
807 	struct channel_reply_ctx *cr = (struct channel_reply_ctx *)ctx;
808 	char errmsg[256];
809 	int tochan;
810 
811 	/*
812 	 * If a TTY was explicitly requested, then a failure to allocate
813 	 * one is fatal.
814 	 */
815 	if (cr->action == CONFIRM_TTY &&
816 	    (options.request_tty == REQUEST_TTY_FORCE ||
817 	    options.request_tty == REQUEST_TTY_YES))
818 		cr->action = CONFIRM_CLOSE;
819 
820 	/* XXX supress on mux _client_ quietmode */
821 	tochan = options.log_level >= SYSLOG_LEVEL_ERROR &&
822 	    c->ctl_chan != -1 && c->extended_usage == CHAN_EXTENDED_WRITE;
823 
824 	if (type == SSH2_MSG_CHANNEL_SUCCESS) {
825 		debug2("%s request accepted on channel %d",
826 		    cr->request_type, c->self);
827 	} else if (type == SSH2_MSG_CHANNEL_FAILURE) {
828 		if (tochan) {
829 			snprintf(errmsg, sizeof(errmsg),
830 			    "%s request failed\r\n", cr->request_type);
831 		} else {
832 			snprintf(errmsg, sizeof(errmsg),
833 			    "%s request failed on channel %d",
834 			    cr->request_type, c->self);
835 		}
836 		/* If error occurred on primary session channel, then exit */
837 		if (cr->action == CONFIRM_CLOSE && c->self == session_ident)
838 			fatal("%s", errmsg);
839 		/*
840 		 * If error occurred on mux client, append to
841 		 * their stderr.
842 		 */
843 		if (tochan) {
844 			buffer_append(&c->extended, errmsg,
845 			    strlen(errmsg));
846 		} else
847 			error("%s", errmsg);
848 		if (cr->action == CONFIRM_TTY) {
849 			/*
850 			 * If a TTY allocation error occurred, then arrange
851 			 * for the correct TTY to leave raw mode.
852 			 */
853 			if (c->self == session_ident)
854 				leave_raw_mode(0);
855 			else
856 				mux_tty_alloc_failed(c);
857 		} else if (cr->action == CONFIRM_CLOSE) {
858 			chan_read_failed(c);
859 			chan_write_failed(c);
860 		}
861 	}
862 	free(cr);
863 }
864 
865 static void
client_abandon_status_confirm(Channel * c,void * ctx)866 client_abandon_status_confirm(Channel *c, void *ctx)
867 {
868 	free(ctx);
869 }
870 
871 void
client_expect_confirm(int id,const char * request,enum confirm_action action)872 client_expect_confirm(int id, const char *request,
873     enum confirm_action action)
874 {
875 	struct channel_reply_ctx *cr = xcalloc(1, sizeof(*cr));
876 
877 	cr->request_type = request;
878 	cr->action = action;
879 
880 	channel_register_status_confirm(id, client_status_confirm,
881 	    client_abandon_status_confirm, cr);
882 }
883 
884 void
client_register_global_confirm(global_confirm_cb * cb,void * ctx)885 client_register_global_confirm(global_confirm_cb *cb, void *ctx)
886 {
887 	struct global_confirm *gc, *last_gc;
888 
889 	/* Coalesce identical callbacks */
890 	last_gc = TAILQ_LAST(&global_confirms, global_confirms);
891 	if (last_gc && last_gc->cb == cb && last_gc->ctx == ctx) {
892 		if (++last_gc->ref_count >= INT_MAX)
893 			fatal("%s: last_gc->ref_count = %d",
894 			    __func__, last_gc->ref_count);
895 		return;
896 	}
897 
898 	gc = xcalloc(1, sizeof(*gc));
899 	gc->cb = cb;
900 	gc->ctx = ctx;
901 	gc->ref_count = 1;
902 	TAILQ_INSERT_TAIL(&global_confirms, gc, entry);
903 }
904 
905 static void
process_cmdline(void)906 process_cmdline(void)
907 {
908 	void (*handler)(int);
909 	char *s, *cmd;
910 	int ok, delete = 0, local = 0, remote = 0, dynamic = 0;
911 	struct Forward fwd;
912 
913 	memset(&fwd, 0, sizeof(fwd));
914 
915 	leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
916 	handler = signal(SIGINT, SIG_IGN);
917 	cmd = s = read_passphrase("\r\nssh> ", RP_ECHO);
918 	if (s == NULL)
919 		goto out;
920 	while (isspace((u_char)*s))
921 		s++;
922 	if (*s == '-')
923 		s++;	/* Skip cmdline '-', if any */
924 	if (*s == '\0')
925 		goto out;
926 
927 	if (*s == 'h' || *s == 'H' || *s == '?') {
928 		logit("Commands:");
929 		logit("      -L[bind_address:]port:host:hostport    "
930 		    "Request local forward");
931 		logit("      -R[bind_address:]port:host:hostport    "
932 		    "Request remote forward");
933 		logit("      -D[bind_address:]port                  "
934 		    "Request dynamic forward");
935 		logit("      -KL[bind_address:]port                 "
936 		    "Cancel local forward");
937 		logit("      -KR[bind_address:]port                 "
938 		    "Cancel remote forward");
939 		logit("      -KD[bind_address:]port                 "
940 		    "Cancel dynamic forward");
941 		if (!options.permit_local_command)
942 			goto out;
943 		logit("      !args                                  "
944 		    "Execute local command");
945 		goto out;
946 	}
947 
948 	if (*s == '!' && options.permit_local_command) {
949 		s++;
950 		ssh_local_cmd(s);
951 		goto out;
952 	}
953 
954 	if (*s == 'K') {
955 		delete = 1;
956 		s++;
957 	}
958 	if (*s == 'L')
959 		local = 1;
960 	else if (*s == 'R')
961 		remote = 1;
962 	else if (*s == 'D')
963 		dynamic = 1;
964 	else {
965 		logit("Invalid command.");
966 		goto out;
967 	}
968 
969 	if (delete && !compat20) {
970 		logit("Not supported for SSH protocol version 1.");
971 		goto out;
972 	}
973 
974 	while (isspace((u_char)*++s))
975 		;
976 
977 	/* XXX update list of forwards in options */
978 	if (delete) {
979 		/* We pass 1 for dynamicfwd to restrict to 1 or 2 fields. */
980 		if (!parse_forward(&fwd, s, 1, 0)) {
981 			logit("Bad forwarding close specification.");
982 			goto out;
983 		}
984 		if (remote)
985 			ok = channel_request_rforward_cancel(&fwd) == 0;
986 		else if (dynamic)
987 			ok = channel_cancel_lport_listener(&fwd,
988 			    0, &options.fwd_opts) > 0;
989 		else
990 			ok = channel_cancel_lport_listener(&fwd,
991 			    CHANNEL_CANCEL_PORT_STATIC,
992 			    &options.fwd_opts) > 0;
993 		if (!ok) {
994 			logit("Unknown port forwarding.");
995 			goto out;
996 		}
997 		logit("Canceled forwarding.");
998 	} else {
999 		if (!parse_forward(&fwd, s, dynamic, remote)) {
1000 			logit("Bad forwarding specification.");
1001 			goto out;
1002 		}
1003 		if (local || dynamic) {
1004 			if (!channel_setup_local_fwd_listener(&fwd,
1005 			    &options.fwd_opts)) {
1006 				logit("Port forwarding failed.");
1007 				goto out;
1008 			}
1009 		} else {
1010 			if (channel_request_remote_forwarding(&fwd) < 0) {
1011 				logit("Port forwarding failed.");
1012 				goto out;
1013 			}
1014 		}
1015 		logit("Forwarding port.");
1016 	}
1017 
1018 out:
1019 	signal(SIGINT, handler);
1020 	enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1021 	free(cmd);
1022 	free(fwd.listen_host);
1023 	free(fwd.listen_path);
1024 	free(fwd.connect_host);
1025 	free(fwd.connect_path);
1026 }
1027 
1028 /* reasons to suppress output of an escape command in help output */
1029 #define SUPPRESS_NEVER		0	/* never suppress, always show */
1030 #define SUPPRESS_PROTO1		1	/* don't show in protocol 1 sessions */
1031 #define SUPPRESS_MUXCLIENT	2	/* don't show in mux client sessions */
1032 #define SUPPRESS_MUXMASTER	4	/* don't show in mux master sessions */
1033 #define SUPPRESS_SYSLOG		8	/* don't show when logging to syslog */
1034 struct escape_help_text {
1035 	const char *cmd;
1036 	const char *text;
1037 	unsigned int flags;
1038 };
1039 static struct escape_help_text esc_txt[] = {
1040     {".",  "terminate session", SUPPRESS_MUXMASTER},
1041     {".",  "terminate connection (and any multiplexed sessions)",
1042 	SUPPRESS_MUXCLIENT},
1043     {"B",  "send a BREAK to the remote system", SUPPRESS_PROTO1},
1044     {"C",  "open a command line", SUPPRESS_MUXCLIENT},
1045     {"R",  "request rekey", SUPPRESS_PROTO1},
1046     {"V/v",  "decrease/increase verbosity (LogLevel)", SUPPRESS_MUXCLIENT},
1047     {"^Z", "suspend ssh", SUPPRESS_MUXCLIENT},
1048     {"#",  "list forwarded connections", SUPPRESS_NEVER},
1049     {"&",  "background ssh (when waiting for connections to terminate)",
1050 	SUPPRESS_MUXCLIENT},
1051     {"?", "this message", SUPPRESS_NEVER},
1052 };
1053 
1054 static void
print_escape_help(Buffer * b,int escape_char,int protocol2,int mux_client,int using_stderr)1055 print_escape_help(Buffer *b, int escape_char, int protocol2, int mux_client,
1056     int using_stderr)
1057 {
1058 	unsigned int i, suppress_flags;
1059 	char string[1024];
1060 
1061 	snprintf(string, sizeof string, "%c?\r\n"
1062 	    "Supported escape sequences:\r\n", escape_char);
1063 	buffer_append(b, string, strlen(string));
1064 
1065 	suppress_flags = (protocol2 ? 0 : SUPPRESS_PROTO1) |
1066 	    (mux_client ? SUPPRESS_MUXCLIENT : 0) |
1067 	    (mux_client ? 0 : SUPPRESS_MUXMASTER) |
1068 	    (using_stderr ? 0 : SUPPRESS_SYSLOG);
1069 
1070 	for (i = 0; i < sizeof(esc_txt)/sizeof(esc_txt[0]); i++) {
1071 		if (esc_txt[i].flags & suppress_flags)
1072 			continue;
1073 		snprintf(string, sizeof string, " %c%-3s - %s\r\n",
1074 		    escape_char, esc_txt[i].cmd, esc_txt[i].text);
1075 		buffer_append(b, string, strlen(string));
1076 	}
1077 
1078 	snprintf(string, sizeof string,
1079 	    " %c%c   - send the escape character by typing it twice\r\n"
1080 	    "(Note that escapes are only recognized immediately after "
1081 	    "newline.)\r\n", escape_char, escape_char);
1082 	buffer_append(b, string, strlen(string));
1083 }
1084 
1085 /*
1086  * Process the characters one by one, call with c==NULL for proto1 case.
1087  */
1088 static int
process_escapes(Channel * c,Buffer * bin,Buffer * bout,Buffer * berr,char * buf,int len)1089 process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr,
1090     char *buf, int len)
1091 {
1092 	char string[1024];
1093 	pid_t pid;
1094 	int bytes = 0;
1095 	u_int i;
1096 	u_char ch;
1097 	char *s;
1098 	int *escape_pendingp, escape_char;
1099 	struct escape_filter_ctx *efc;
1100 
1101 	if (c == NULL) {
1102 		escape_pendingp = &escape_pending1;
1103 		escape_char = escape_char1;
1104 	} else {
1105 		if (c->filter_ctx == NULL)
1106 			return 0;
1107 		efc = (struct escape_filter_ctx *)c->filter_ctx;
1108 		escape_pendingp = &efc->escape_pending;
1109 		escape_char = efc->escape_char;
1110 	}
1111 
1112 	if (len <= 0)
1113 		return (0);
1114 
1115 	for (i = 0; i < (u_int)len; i++) {
1116 		/* Get one character at a time. */
1117 		ch = buf[i];
1118 
1119 		if (*escape_pendingp) {
1120 			/* We have previously seen an escape character. */
1121 			/* Clear the flag now. */
1122 			*escape_pendingp = 0;
1123 
1124 			/* Process the escaped character. */
1125 			switch (ch) {
1126 			case '.':
1127 				/* Terminate the connection. */
1128 				snprintf(string, sizeof string, "%c.\r\n",
1129 				    escape_char);
1130 				buffer_append(berr, string, strlen(string));
1131 
1132 				if (c && c->ctl_chan != -1) {
1133 					chan_read_failed(c);
1134 					chan_write_failed(c);
1135 					if (c->detach_user)
1136 						c->detach_user(c->self, NULL);
1137 					c->type = SSH_CHANNEL_ABANDONED;
1138 					buffer_clear(&c->input);
1139 					chan_ibuf_empty(c);
1140 					return 0;
1141 				} else
1142 					quit_pending = 1;
1143 				return -1;
1144 
1145 			case 'Z' - 64:
1146 				/* XXX support this for mux clients */
1147 				if (c && c->ctl_chan != -1) {
1148 					char b[16];
1149  noescape:
1150 					if (ch == 'Z' - 64)
1151 						snprintf(b, sizeof b, "^Z");
1152 					else
1153 						snprintf(b, sizeof b, "%c", ch);
1154 					snprintf(string, sizeof string,
1155 					    "%c%s escape not available to "
1156 					    "multiplexed sessions\r\n",
1157 					    escape_char, b);
1158 					buffer_append(berr, string,
1159 					    strlen(string));
1160 					continue;
1161 				}
1162 				/* Suspend the program. Inform the user */
1163 				snprintf(string, sizeof string,
1164 				    "%c^Z [suspend ssh]\r\n", escape_char);
1165 				buffer_append(berr, string, strlen(string));
1166 
1167 				/* Restore terminal modes and suspend. */
1168 				client_suspend_self(bin, bout, berr);
1169 
1170 				/* We have been continued. */
1171 				continue;
1172 
1173 			case 'B':
1174 				if (compat20) {
1175 					snprintf(string, sizeof string,
1176 					    "%cB\r\n", escape_char);
1177 					buffer_append(berr, string,
1178 					    strlen(string));
1179 					channel_request_start(c->self,
1180 					    "break", 0);
1181 					packet_put_int(1000);
1182 					packet_send();
1183 				}
1184 				continue;
1185 
1186 			case 'R':
1187 				if (compat20) {
1188 					if (datafellows & SSH_BUG_NOREKEY)
1189 						logit("Server does not "
1190 						    "support re-keying");
1191 					else
1192 						need_rekeying = 1;
1193 				}
1194 				continue;
1195 
1196 			case 'V':
1197 				/* FALLTHROUGH */
1198 			case 'v':
1199 				if (c && c->ctl_chan != -1)
1200 					goto noescape;
1201 				if (!log_is_on_stderr()) {
1202 					snprintf(string, sizeof string,
1203 					    "%c%c [Logging to syslog]\r\n",
1204 					     escape_char, ch);
1205 					buffer_append(berr, string,
1206 					    strlen(string));
1207 					continue;
1208 				}
1209 				if (ch == 'V' && options.log_level >
1210 				    SYSLOG_LEVEL_QUIET)
1211 					log_change_level(--options.log_level);
1212 				if (ch == 'v' && options.log_level <
1213 				    SYSLOG_LEVEL_DEBUG3)
1214 					log_change_level(++options.log_level);
1215 				snprintf(string, sizeof string,
1216 				    "%c%c [LogLevel %s]\r\n", escape_char, ch,
1217 				    log_level_name(options.log_level));
1218 				buffer_append(berr, string, strlen(string));
1219 				continue;
1220 
1221 			case '&':
1222 				if (c && c->ctl_chan != -1)
1223 					goto noescape;
1224 				/*
1225 				 * Detach the program (continue to serve
1226 				 * connections, but put in background and no
1227 				 * more new connections).
1228 				 */
1229 				/* Restore tty modes. */
1230 				leave_raw_mode(
1231 				    options.request_tty == REQUEST_TTY_FORCE);
1232 
1233 				/* Stop listening for new connections. */
1234 				channel_stop_listening();
1235 
1236 				snprintf(string, sizeof string,
1237 				    "%c& [backgrounded]\n", escape_char);
1238 				buffer_append(berr, string, strlen(string));
1239 
1240 				/* Fork into background. */
1241 				pid = fork();
1242 				if (pid < 0) {
1243 					error("fork: %.100s", strerror(errno));
1244 					continue;
1245 				}
1246 				if (pid != 0) {	/* This is the parent. */
1247 					/* The parent just exits. */
1248 					exit(0);
1249 				}
1250 				/* The child continues serving connections. */
1251 				if (compat20) {
1252 					buffer_append(bin, "\004", 1);
1253 					/* fake EOF on stdin */
1254 					return -1;
1255 				} else if (!stdin_eof) {
1256 					/*
1257 					 * Sending SSH_CMSG_EOF alone does not
1258 					 * always appear to be enough.  So we
1259 					 * try to send an EOF character first.
1260 					 */
1261 					packet_start(SSH_CMSG_STDIN_DATA);
1262 					packet_put_string("\004", 1);
1263 					packet_send();
1264 					/* Close stdin. */
1265 					stdin_eof = 1;
1266 					if (buffer_len(bin) == 0) {
1267 						packet_start(SSH_CMSG_EOF);
1268 						packet_send();
1269 					}
1270 				}
1271 				continue;
1272 
1273 			case '?':
1274 				print_escape_help(berr, escape_char, compat20,
1275 				    (c && c->ctl_chan != -1),
1276 				    log_is_on_stderr());
1277 				continue;
1278 
1279 			case '#':
1280 				snprintf(string, sizeof string, "%c#\r\n",
1281 				    escape_char);
1282 				buffer_append(berr, string, strlen(string));
1283 				s = channel_open_message();
1284 				buffer_append(berr, s, strlen(s));
1285 				free(s);
1286 				continue;
1287 
1288 			case 'C':
1289 				if (c && c->ctl_chan != -1)
1290 					goto noescape;
1291 				process_cmdline();
1292 				continue;
1293 
1294 			default:
1295 				if (ch != escape_char) {
1296 					buffer_put_char(bin, escape_char);
1297 					bytes++;
1298 				}
1299 				/* Escaped characters fall through here */
1300 				break;
1301 			}
1302 		} else {
1303 			/*
1304 			 * The previous character was not an escape char.
1305 			 * Check if this is an escape.
1306 			 */
1307 			if (last_was_cr && ch == escape_char) {
1308 				/*
1309 				 * It is. Set the flag and continue to
1310 				 * next character.
1311 				 */
1312 				*escape_pendingp = 1;
1313 				continue;
1314 			}
1315 		}
1316 
1317 		/*
1318 		 * Normal character.  Record whether it was a newline,
1319 		 * and append it to the buffer.
1320 		 */
1321 		last_was_cr = (ch == '\r' || ch == '\n');
1322 		buffer_put_char(bin, ch);
1323 		bytes++;
1324 	}
1325 	return bytes;
1326 }
1327 
1328 static void
client_process_input(fd_set * readset)1329 client_process_input(fd_set *readset)
1330 {
1331 	int len;
1332 	char buf[SSH_IOBUFSZ];
1333 
1334 	/* Read input from stdin. */
1335 	if (FD_ISSET(fileno(stdin), readset)) {
1336 		/* Read as much as possible. */
1337 		len = read(fileno(stdin), buf, sizeof(buf));
1338 		if (len < 0 &&
1339 		    (errno == EAGAIN || errno == EINTR || errno == EWOULDBLOCK))
1340 			return;		/* we'll try again later */
1341 		if (len <= 0) {
1342 			/*
1343 			 * Received EOF or error.  They are treated
1344 			 * similarly, except that an error message is printed
1345 			 * if it was an error condition.
1346 			 */
1347 			if (len < 0) {
1348 				snprintf(buf, sizeof buf, "read: %.100s\r\n",
1349 				    strerror(errno));
1350 				buffer_append(&stderr_buffer, buf, strlen(buf));
1351 			}
1352 			/* Mark that we have seen EOF. */
1353 			stdin_eof = 1;
1354 			/*
1355 			 * Send an EOF message to the server unless there is
1356 			 * data in the buffer.  If there is data in the
1357 			 * buffer, no message will be sent now.  Code
1358 			 * elsewhere will send the EOF when the buffer
1359 			 * becomes empty if stdin_eof is set.
1360 			 */
1361 			if (buffer_len(&stdin_buffer) == 0) {
1362 				packet_start(SSH_CMSG_EOF);
1363 				packet_send();
1364 			}
1365 		} else if (escape_char1 == SSH_ESCAPECHAR_NONE) {
1366 			/*
1367 			 * Normal successful read, and no escape character.
1368 			 * Just append the data to buffer.
1369 			 */
1370 			buffer_append(&stdin_buffer, buf, len);
1371 		} else {
1372 			/*
1373 			 * Normal, successful read.  But we have an escape
1374 			 * character and have to process the characters one
1375 			 * by one.
1376 			 */
1377 			if (process_escapes(NULL, &stdin_buffer,
1378 			    &stdout_buffer, &stderr_buffer, buf, len) == -1)
1379 				return;
1380 		}
1381 	}
1382 }
1383 
1384 static void
client_process_output(fd_set * writeset)1385 client_process_output(fd_set *writeset)
1386 {
1387 	int len;
1388 	char buf[100];
1389 
1390 	/* Write buffered output to stdout. */
1391 	if (FD_ISSET(fileno(stdout), writeset)) {
1392 		/* Write as much data as possible. */
1393 		len = write(fileno(stdout), buffer_ptr(&stdout_buffer),
1394 		    buffer_len(&stdout_buffer));
1395 		if (len <= 0) {
1396 			if (errno == EINTR || errno == EAGAIN ||
1397 			    errno == EWOULDBLOCK)
1398 				len = 0;
1399 			else {
1400 				/*
1401 				 * An error or EOF was encountered.  Put an
1402 				 * error message to stderr buffer.
1403 				 */
1404 				snprintf(buf, sizeof buf,
1405 				    "write stdout: %.50s\r\n", strerror(errno));
1406 				buffer_append(&stderr_buffer, buf, strlen(buf));
1407 				quit_pending = 1;
1408 				return;
1409 			}
1410 		}
1411 		/* Consume printed data from the buffer. */
1412 		buffer_consume(&stdout_buffer, len);
1413 	}
1414 	/* Write buffered output to stderr. */
1415 	if (FD_ISSET(fileno(stderr), writeset)) {
1416 		/* Write as much data as possible. */
1417 		len = write(fileno(stderr), buffer_ptr(&stderr_buffer),
1418 		    buffer_len(&stderr_buffer));
1419 		if (len <= 0) {
1420 			if (errno == EINTR || errno == EAGAIN ||
1421 			    errno == EWOULDBLOCK)
1422 				len = 0;
1423 			else {
1424 				/*
1425 				 * EOF or error, but can't even print
1426 				 * error message.
1427 				 */
1428 				quit_pending = 1;
1429 				return;
1430 			}
1431 		}
1432 		/* Consume printed characters from the buffer. */
1433 		buffer_consume(&stderr_buffer, len);
1434 	}
1435 }
1436 
1437 /*
1438  * Get packets from the connection input buffer, and process them as long as
1439  * there are packets available.
1440  *
1441  * Any unknown packets received during the actual
1442  * session cause the session to terminate.  This is
1443  * intended to make debugging easier since no
1444  * confirmations are sent.  Any compatible protocol
1445  * extensions must be negotiated during the
1446  * preparatory phase.
1447  */
1448 
1449 static void
client_process_buffered_input_packets(void)1450 client_process_buffered_input_packets(void)
1451 {
1452 	dispatch_run(DISPATCH_NONBLOCK, &quit_pending, active_state);
1453 }
1454 
1455 /* scan buf[] for '~' before sending data to the peer */
1456 
1457 /* Helper: allocate a new escape_filter_ctx and fill in its escape char */
1458 void *
client_new_escape_filter_ctx(int escape_char)1459 client_new_escape_filter_ctx(int escape_char)
1460 {
1461 	struct escape_filter_ctx *ret;
1462 
1463 	ret = xcalloc(1, sizeof(*ret));
1464 	ret->escape_pending = 0;
1465 	ret->escape_char = escape_char;
1466 	return (void *)ret;
1467 }
1468 
1469 /* Free the escape filter context on channel free */
1470 void
client_filter_cleanup(int cid,void * ctx)1471 client_filter_cleanup(int cid, void *ctx)
1472 {
1473 	free(ctx);
1474 }
1475 
1476 int
client_simple_escape_filter(Channel * c,char * buf,int len)1477 client_simple_escape_filter(Channel *c, char *buf, int len)
1478 {
1479 	if (c->extended_usage != CHAN_EXTENDED_WRITE)
1480 		return 0;
1481 
1482 	return process_escapes(c, &c->input, &c->output, &c->extended,
1483 	    buf, len);
1484 }
1485 
1486 static void
client_channel_closed(int id,void * arg)1487 client_channel_closed(int id, void *arg)
1488 {
1489 	channel_cancel_cleanup(id);
1490 	session_closed = 1;
1491 	leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1492 }
1493 
1494 /*
1495  * Implements the interactive session with the server.  This is called after
1496  * the user has been authenticated, and a command has been started on the
1497  * remote host.  If escape_char != SSH_ESCAPECHAR_NONE, it is the character
1498  * used as an escape character for terminating or suspending the session.
1499  */
1500 
1501 int
client_loop(int have_pty,int escape_char_arg,int ssh2_chan_id)1502 client_loop(int have_pty, int escape_char_arg, int ssh2_chan_id)
1503 {
1504 	fd_set *readset = NULL, *writeset = NULL;
1505 	double start_time, total_time;
1506 	int r, max_fd = 0, max_fd2 = 0, len;
1507 	u_int64_t ibytes, obytes;
1508 	u_int nalloc = 0;
1509 	char buf[100];
1510 
1511 	debug("Entering interactive session.");
1512 
1513 	if (options.control_master &&
1514 	    !option_clear_or_none(options.control_path)) {
1515 		debug("pledge: id");
1516 		if (pledge("stdio rpath wpath cpath unix inet dns recvfd proc exec id tty",
1517 		    NULL) == -1)
1518 			fatal("%s pledge(): %s", __func__, strerror(errno));
1519 
1520 	} else if (options.forward_x11 || options.permit_local_command) {
1521 		debug("pledge: exec");
1522 		if (pledge("stdio rpath wpath cpath unix inet dns proc exec tty",
1523 		    NULL) == -1)
1524 			fatal("%s pledge(): %s", __func__, strerror(errno));
1525 
1526 	} else if (options.update_hostkeys) {
1527 		debug("pledge: filesystem full");
1528 		if (pledge("stdio rpath wpath cpath unix inet dns proc tty",
1529 		    NULL) == -1)
1530 			fatal("%s pledge(): %s", __func__, strerror(errno));
1531 
1532 	} else if (!option_clear_or_none(options.proxy_command) ||
1533 	    fork_after_authentication_flag) {
1534 		debug("pledge: proc");
1535 		if (pledge("stdio cpath unix inet dns proc tty", NULL) == -1)
1536 			fatal("%s pledge(): %s", __func__, strerror(errno));
1537 
1538 	} else {
1539 		debug("pledge: network");
1540 		if (pledge("stdio unix inet dns tty", NULL) == -1)
1541 			fatal("%s pledge(): %s", __func__, strerror(errno));
1542 	}
1543 
1544 	start_time = get_current_time();
1545 
1546 	/* Initialize variables. */
1547 	escape_pending1 = 0;
1548 	last_was_cr = 1;
1549 	exit_status = -1;
1550 	stdin_eof = 0;
1551 	buffer_high = 64 * 1024;
1552 	connection_in = packet_get_connection_in();
1553 	connection_out = packet_get_connection_out();
1554 	max_fd = MAXIMUM(connection_in, connection_out);
1555 
1556 	if (!compat20) {
1557 		/* enable nonblocking unless tty */
1558 		if (!isatty(fileno(stdin)))
1559 			set_nonblock(fileno(stdin));
1560 		if (!isatty(fileno(stdout)))
1561 			set_nonblock(fileno(stdout));
1562 		if (!isatty(fileno(stderr)))
1563 			set_nonblock(fileno(stderr));
1564 		max_fd = MAXIMUM(max_fd, fileno(stdin));
1565 		max_fd = MAXIMUM(max_fd, fileno(stdout));
1566 		max_fd = MAXIMUM(max_fd, fileno(stderr));
1567 	}
1568 	quit_pending = 0;
1569 	escape_char1 = escape_char_arg;
1570 
1571 	/* Initialize buffers. */
1572 	buffer_init(&stdin_buffer);
1573 	buffer_init(&stdout_buffer);
1574 	buffer_init(&stderr_buffer);
1575 
1576 	client_init_dispatch();
1577 
1578 	/*
1579 	 * Set signal handlers, (e.g. to restore non-blocking mode)
1580 	 * but don't overwrite SIG_IGN, matches behaviour from rsh(1)
1581 	 */
1582 	if (signal(SIGHUP, SIG_IGN) != SIG_IGN)
1583 		signal(SIGHUP, signal_handler);
1584 	if (signal(SIGINT, SIG_IGN) != SIG_IGN)
1585 		signal(SIGINT, signal_handler);
1586 	if (signal(SIGQUIT, SIG_IGN) != SIG_IGN)
1587 		signal(SIGQUIT, signal_handler);
1588 	if (signal(SIGTERM, SIG_IGN) != SIG_IGN)
1589 		signal(SIGTERM, signal_handler);
1590 	signal(SIGWINCH, window_change_handler);
1591 
1592 	if (have_pty)
1593 		enter_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1594 
1595 	if (compat20) {
1596 		session_ident = ssh2_chan_id;
1597 		if (session_ident != -1) {
1598 			if (escape_char_arg != SSH_ESCAPECHAR_NONE) {
1599 				channel_register_filter(session_ident,
1600 				    client_simple_escape_filter, NULL,
1601 				    client_filter_cleanup,
1602 				    client_new_escape_filter_ctx(
1603 				    escape_char_arg));
1604 			}
1605 			channel_register_cleanup(session_ident,
1606 			    client_channel_closed, 0);
1607 		}
1608 	} else {
1609 		/* Check if we should immediately send eof on stdin. */
1610 		client_check_initial_eof_on_stdin();
1611 	}
1612 
1613 	/* Main loop of the client for the interactive session mode. */
1614 	while (!quit_pending) {
1615 
1616 		/* Process buffered packets sent by the server. */
1617 		client_process_buffered_input_packets();
1618 
1619 		if (compat20 && session_closed && !channel_still_open())
1620 			break;
1621 
1622 		if (ssh_packet_is_rekeying(active_state)) {
1623 			debug("rekeying in progress");
1624 		} else if (need_rekeying) {
1625 			/* manual rekey request */
1626 			debug("need rekeying");
1627 			if ((r = kex_start_rekex(active_state)) != 0)
1628 				fatal("%s: kex_start_rekex: %s", __func__,
1629 				    ssh_err(r));
1630 			need_rekeying = 0;
1631 		} else {
1632 			/*
1633 			 * Make packets of buffered stdin data, and buffer
1634 			 * them for sending to the server.
1635 			 */
1636 			if (!compat20)
1637 				client_make_packets_from_stdin_data();
1638 
1639 			/*
1640 			 * Make packets from buffered channel data, and
1641 			 * enqueue them for sending to the server.
1642 			 */
1643 			if (packet_not_very_much_data_to_write())
1644 				channel_output_poll();
1645 
1646 			/*
1647 			 * Check if the window size has changed, and buffer a
1648 			 * message about it to the server if so.
1649 			 */
1650 			client_check_window_change();
1651 
1652 			if (quit_pending)
1653 				break;
1654 		}
1655 		/*
1656 		 * Wait until we have something to do (something becomes
1657 		 * available on one of the descriptors).
1658 		 */
1659 		max_fd2 = max_fd;
1660 		client_wait_until_can_do_something(&readset, &writeset,
1661 		    &max_fd2, &nalloc, ssh_packet_is_rekeying(active_state));
1662 
1663 		if (quit_pending)
1664 			break;
1665 
1666 		/* Do channel operations unless rekeying in progress. */
1667 		if (!ssh_packet_is_rekeying(active_state))
1668 			channel_after_select(readset, writeset);
1669 
1670 		/* Buffer input from the connection.  */
1671 		client_process_net_input(readset);
1672 
1673 		if (quit_pending)
1674 			break;
1675 
1676 		if (!compat20) {
1677 			/* Buffer data from stdin */
1678 			client_process_input(readset);
1679 			/*
1680 			 * Process output to stdout and stderr.  Output to
1681 			 * the connection is processed elsewhere (above).
1682 			 */
1683 			client_process_output(writeset);
1684 		}
1685 
1686 		/*
1687 		 * Send as much buffered packet data as possible to the
1688 		 * sender.
1689 		 */
1690 		if (FD_ISSET(connection_out, writeset))
1691 			packet_write_poll();
1692 
1693 		/*
1694 		 * If we are a backgrounded control master, and the
1695 		 * timeout has expired without any active client
1696 		 * connections, then quit.
1697 		 */
1698 		if (control_persist_exit_time > 0) {
1699 			if (monotime() >= control_persist_exit_time) {
1700 				debug("ControlPersist timeout expired");
1701 				break;
1702 			}
1703 		}
1704 	}
1705 	free(readset);
1706 	free(writeset);
1707 
1708 	/* Terminate the session. */
1709 
1710 	/* Stop watching for window change. */
1711 	signal(SIGWINCH, SIG_DFL);
1712 
1713 	if (compat20) {
1714 		packet_start(SSH2_MSG_DISCONNECT);
1715 		packet_put_int(SSH2_DISCONNECT_BY_APPLICATION);
1716 		packet_put_cstring("disconnected by user");
1717 		packet_put_cstring(""); /* language tag */
1718 		packet_send();
1719 		packet_write_wait();
1720 	}
1721 
1722 	channel_free_all();
1723 
1724 	if (have_pty)
1725 		leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
1726 
1727 	/* restore blocking io */
1728 	if (!isatty(fileno(stdin)))
1729 		unset_nonblock(fileno(stdin));
1730 	if (!isatty(fileno(stdout)))
1731 		unset_nonblock(fileno(stdout));
1732 	if (!isatty(fileno(stderr)))
1733 		unset_nonblock(fileno(stderr));
1734 
1735 	/*
1736 	 * If there was no shell or command requested, there will be no remote
1737 	 * exit status to be returned.  In that case, clear error code if the
1738 	 * connection was deliberately terminated at this end.
1739 	 */
1740 	if (no_shell_flag && received_signal == SIGTERM) {
1741 		received_signal = 0;
1742 		exit_status = 0;
1743 	}
1744 
1745 	if (received_signal)
1746 		fatal("Killed by signal %d.", (int) received_signal);
1747 
1748 	/*
1749 	 * In interactive mode (with pseudo tty) display a message indicating
1750 	 * that the connection has been closed.
1751 	 */
1752 	if (have_pty && options.log_level != SYSLOG_LEVEL_QUIET) {
1753 		snprintf(buf, sizeof buf,
1754 		    "Connection to %.64s closed.\r\n", host);
1755 		buffer_append(&stderr_buffer, buf, strlen(buf));
1756 	}
1757 
1758 	/* Output any buffered data for stdout. */
1759 	if (buffer_len(&stdout_buffer) > 0) {
1760 		len = atomicio(vwrite, fileno(stdout),
1761 		    buffer_ptr(&stdout_buffer), buffer_len(&stdout_buffer));
1762 		if (len < 0 || (u_int)len != buffer_len(&stdout_buffer))
1763 			error("Write failed flushing stdout buffer.");
1764 		else
1765 			buffer_consume(&stdout_buffer, len);
1766 	}
1767 
1768 	/* Output any buffered data for stderr. */
1769 	if (buffer_len(&stderr_buffer) > 0) {
1770 		len = atomicio(vwrite, fileno(stderr),
1771 		    buffer_ptr(&stderr_buffer), buffer_len(&stderr_buffer));
1772 		if (len < 0 || (u_int)len != buffer_len(&stderr_buffer))
1773 			error("Write failed flushing stderr buffer.");
1774 		else
1775 			buffer_consume(&stderr_buffer, len);
1776 	}
1777 
1778 	/* Clear and free any buffers. */
1779 	explicit_bzero(buf, sizeof(buf));
1780 	buffer_free(&stdin_buffer);
1781 	buffer_free(&stdout_buffer);
1782 	buffer_free(&stderr_buffer);
1783 
1784 	/* Report bytes transferred, and transfer rates. */
1785 	total_time = get_current_time() - start_time;
1786 	packet_get_bytes(&ibytes, &obytes);
1787 	verbose("Transferred: sent %llu, received %llu bytes, in %.1f seconds",
1788 	    (unsigned long long)obytes, (unsigned long long)ibytes, total_time);
1789 	if (total_time > 0)
1790 		verbose("Bytes per second: sent %.1f, received %.1f",
1791 		    obytes / total_time, ibytes / total_time);
1792 	/* Return the exit status of the program. */
1793 	debug("Exit status %d", exit_status);
1794 	return exit_status;
1795 }
1796 
1797 /*********/
1798 
1799 static int
client_input_stdout_data(int type,u_int32_t seq,void * ctxt)1800 client_input_stdout_data(int type, u_int32_t seq, void *ctxt)
1801 {
1802 	u_int data_len;
1803 	char *data = packet_get_string(&data_len);
1804 	packet_check_eom();
1805 	buffer_append(&stdout_buffer, data, data_len);
1806 	explicit_bzero(data, data_len);
1807 	free(data);
1808 	return 0;
1809 }
1810 static int
client_input_stderr_data(int type,u_int32_t seq,void * ctxt)1811 client_input_stderr_data(int type, u_int32_t seq, void *ctxt)
1812 {
1813 	u_int data_len;
1814 	char *data = packet_get_string(&data_len);
1815 	packet_check_eom();
1816 	buffer_append(&stderr_buffer, data, data_len);
1817 	explicit_bzero(data, data_len);
1818 	free(data);
1819 	return 0;
1820 }
1821 static int
client_input_exit_status(int type,u_int32_t seq,void * ctxt)1822 client_input_exit_status(int type, u_int32_t seq, void *ctxt)
1823 {
1824 	exit_status = packet_get_int();
1825 	packet_check_eom();
1826 	/* Acknowledge the exit. */
1827 	packet_start(SSH_CMSG_EXIT_CONFIRMATION);
1828 	packet_send();
1829 	/*
1830 	 * Must wait for packet to be sent since we are
1831 	 * exiting the loop.
1832 	 */
1833 	packet_write_wait();
1834 	/* Flag that we want to exit. */
1835 	quit_pending = 1;
1836 	return 0;
1837 }
1838 
1839 static int
client_input_agent_open(int type,u_int32_t seq,void * ctxt)1840 client_input_agent_open(int type, u_int32_t seq, void *ctxt)
1841 {
1842 	Channel *c = NULL;
1843 	int r, remote_id, sock;
1844 
1845 	/* Read the remote channel number from the message. */
1846 	remote_id = packet_get_int();
1847 	packet_check_eom();
1848 
1849 	/*
1850 	 * Get a connection to the local authentication agent (this may again
1851 	 * get forwarded).
1852 	 */
1853 	if ((r = ssh_get_authentication_socket(&sock)) != 0 &&
1854 	    r != SSH_ERR_AGENT_NOT_PRESENT)
1855 		debug("%s: ssh_get_authentication_socket: %s",
1856 		    __func__, ssh_err(r));
1857 
1858 
1859 	/*
1860 	 * If we could not connect the agent, send an error message back to
1861 	 * the server. This should never happen unless the agent dies,
1862 	 * because authentication forwarding is only enabled if we have an
1863 	 * agent.
1864 	 */
1865 	if (sock >= 0) {
1866 		c = channel_new("", SSH_CHANNEL_OPEN, sock, sock,
1867 		    -1, 0, 0, 0, "authentication agent connection", 1);
1868 		c->remote_id = remote_id;
1869 		c->force_drain = 1;
1870 	}
1871 	if (c == NULL) {
1872 		packet_start(SSH_MSG_CHANNEL_OPEN_FAILURE);
1873 		packet_put_int(remote_id);
1874 	} else {
1875 		/* Send a confirmation to the remote host. */
1876 		debug("Forwarding authentication connection.");
1877 		packet_start(SSH_MSG_CHANNEL_OPEN_CONFIRMATION);
1878 		packet_put_int(remote_id);
1879 		packet_put_int(c->self);
1880 	}
1881 	packet_send();
1882 	return 0;
1883 }
1884 
1885 static Channel *
client_request_forwarded_tcpip(const char * request_type,int rchan,u_int rwindow,u_int rmaxpack)1886 client_request_forwarded_tcpip(const char *request_type, int rchan,
1887     u_int rwindow, u_int rmaxpack)
1888 {
1889 	Channel *c = NULL;
1890 	struct sshbuf *b = NULL;
1891 	char *listen_address, *originator_address;
1892 	u_short listen_port, originator_port;
1893 	int r;
1894 
1895 	/* Get rest of the packet */
1896 	listen_address = packet_get_string(NULL);
1897 	listen_port = packet_get_int();
1898 	originator_address = packet_get_string(NULL);
1899 	originator_port = packet_get_int();
1900 	packet_check_eom();
1901 
1902 	debug("%s: listen %s port %d, originator %s port %d", __func__,
1903 	    listen_address, listen_port, originator_address, originator_port);
1904 
1905 	c = channel_connect_by_listen_address(listen_address, listen_port,
1906 	    "forwarded-tcpip", originator_address);
1907 
1908 	if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
1909 		if ((b = sshbuf_new()) == NULL) {
1910 			error("%s: alloc reply", __func__);
1911 			goto out;
1912 		}
1913 		/* reconstruct and send to muxclient */
1914 		if ((r = sshbuf_put_u8(b, 0)) != 0 ||	/* padlen */
1915 		    (r = sshbuf_put_u8(b, SSH2_MSG_CHANNEL_OPEN)) != 0 ||
1916 		    (r = sshbuf_put_cstring(b, request_type)) != 0 ||
1917 		    (r = sshbuf_put_u32(b, rchan)) != 0 ||
1918 		    (r = sshbuf_put_u32(b, rwindow)) != 0 ||
1919 		    (r = sshbuf_put_u32(b, rmaxpack)) != 0 ||
1920 		    (r = sshbuf_put_cstring(b, listen_address)) != 0 ||
1921 		    (r = sshbuf_put_u32(b, listen_port)) != 0 ||
1922 		    (r = sshbuf_put_cstring(b, originator_address)) != 0 ||
1923 		    (r = sshbuf_put_u32(b, originator_port)) != 0 ||
1924 		    (r = sshbuf_put_stringb(&c->output, b)) != 0) {
1925 			error("%s: compose for muxclient %s", __func__,
1926 			    ssh_err(r));
1927 			goto out;
1928 		}
1929 	}
1930 
1931  out:
1932 	sshbuf_free(b);
1933 	free(originator_address);
1934 	free(listen_address);
1935 	return c;
1936 }
1937 
1938 static Channel *
client_request_forwarded_streamlocal(const char * request_type,int rchan)1939 client_request_forwarded_streamlocal(const char *request_type, int rchan)
1940 {
1941 	Channel *c = NULL;
1942 	char *listen_path;
1943 
1944 	/* Get the remote path. */
1945 	listen_path = packet_get_string(NULL);
1946 	/* XXX: Skip reserved field for now. */
1947 	if (packet_get_string_ptr(NULL) == NULL)
1948 		fatal("%s: packet_get_string_ptr failed", __func__);
1949 	packet_check_eom();
1950 
1951 	debug("%s: %s", __func__, listen_path);
1952 
1953 	c = channel_connect_by_listen_path(listen_path,
1954 	    "forwarded-streamlocal@openssh.com", "forwarded-streamlocal");
1955 	free(listen_path);
1956 	return c;
1957 }
1958 
1959 static Channel *
client_request_x11(const char * request_type,int rchan)1960 client_request_x11(const char *request_type, int rchan)
1961 {
1962 	Channel *c = NULL;
1963 	char *originator;
1964 	u_short originator_port;
1965 	int sock;
1966 
1967 	if (!options.forward_x11) {
1968 		error("Warning: ssh server tried X11 forwarding.");
1969 		error("Warning: this is probably a break-in attempt by a "
1970 		    "malicious server.");
1971 		return NULL;
1972 	}
1973 	if (x11_refuse_time != 0 && (u_int)monotime() >= x11_refuse_time) {
1974 		verbose("Rejected X11 connection after ForwardX11Timeout "
1975 		    "expired");
1976 		return NULL;
1977 	}
1978 	originator = packet_get_string(NULL);
1979 	if (datafellows & SSH_BUG_X11FWD) {
1980 		debug2("buggy server: x11 request w/o originator_port");
1981 		originator_port = 0;
1982 	} else {
1983 		originator_port = packet_get_int();
1984 	}
1985 	packet_check_eom();
1986 	/* XXX check permission */
1987 	debug("client_request_x11: request from %s %d", originator,
1988 	    originator_port);
1989 	free(originator);
1990 	sock = x11_connect_display();
1991 	if (sock < 0)
1992 		return NULL;
1993 	c = channel_new("x11",
1994 	    SSH_CHANNEL_X11_OPEN, sock, sock, -1,
1995 	    CHAN_TCP_WINDOW_DEFAULT, CHAN_X11_PACKET_DEFAULT, 0, "x11", 1);
1996 	c->force_drain = 1;
1997 	return c;
1998 }
1999 
2000 static Channel *
client_request_agent(const char * request_type,int rchan)2001 client_request_agent(const char *request_type, int rchan)
2002 {
2003 	Channel *c = NULL;
2004 	int r, sock;
2005 
2006 	if (!options.forward_agent) {
2007 		error("Warning: ssh server tried agent forwarding.");
2008 		error("Warning: this is probably a break-in attempt by a "
2009 		    "malicious server.");
2010 		return NULL;
2011 	}
2012 	if ((r = ssh_get_authentication_socket(&sock)) != 0) {
2013 		if (r != SSH_ERR_AGENT_NOT_PRESENT)
2014 			debug("%s: ssh_get_authentication_socket: %s",
2015 			    __func__, ssh_err(r));
2016 		return NULL;
2017 	}
2018 	c = channel_new("authentication agent connection",
2019 	    SSH_CHANNEL_OPEN, sock, sock, -1,
2020 	    CHAN_X11_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0,
2021 	    "authentication agent connection", 1);
2022 	c->force_drain = 1;
2023 	return c;
2024 }
2025 
2026 int
client_request_tun_fwd(int tun_mode,int local_tun,int remote_tun)2027 client_request_tun_fwd(int tun_mode, int local_tun, int remote_tun)
2028 {
2029 	Channel *c;
2030 	int fd;
2031 
2032 	if (tun_mode == SSH_TUNMODE_NO)
2033 		return 0;
2034 
2035 	if (!compat20) {
2036 		error("Tunnel forwarding is not supported for protocol 1");
2037 		return -1;
2038 	}
2039 
2040 	debug("Requesting tun unit %d in mode %d", local_tun, tun_mode);
2041 
2042 	/* Open local tunnel device */
2043 	if ((fd = tun_open(local_tun, tun_mode)) == -1) {
2044 		error("Tunnel device open failed.");
2045 		return -1;
2046 	}
2047 
2048 	c = channel_new("tun", SSH_CHANNEL_OPENING, fd, fd, -1,
2049 	    CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
2050 	c->datagram = 1;
2051 
2052 #if defined(SSH_TUN_FILTER)
2053 	if (options.tun_open == SSH_TUNMODE_POINTOPOINT)
2054 		channel_register_filter(c->self, sys_tun_infilter,
2055 		    sys_tun_outfilter, NULL, NULL);
2056 #endif
2057 
2058 	packet_start(SSH2_MSG_CHANNEL_OPEN);
2059 	packet_put_cstring("tun@openssh.com");
2060 	packet_put_int(c->self);
2061 	packet_put_int(c->local_window_max);
2062 	packet_put_int(c->local_maxpacket);
2063 	packet_put_int(tun_mode);
2064 	packet_put_int(remote_tun);
2065 	packet_send();
2066 
2067 	return 0;
2068 }
2069 
2070 /* XXXX move to generic input handler */
2071 static int
client_input_channel_open(int type,u_int32_t seq,void * ctxt)2072 client_input_channel_open(int type, u_int32_t seq, void *ctxt)
2073 {
2074 	Channel *c = NULL;
2075 	char *ctype;
2076 	int rchan;
2077 	u_int rmaxpack, rwindow, len;
2078 
2079 	ctype = packet_get_string(&len);
2080 	rchan = packet_get_int();
2081 	rwindow = packet_get_int();
2082 	rmaxpack = packet_get_int();
2083 
2084 	debug("client_input_channel_open: ctype %s rchan %d win %d max %d",
2085 	    ctype, rchan, rwindow, rmaxpack);
2086 
2087 	if (strcmp(ctype, "forwarded-tcpip") == 0) {
2088 		c = client_request_forwarded_tcpip(ctype, rchan, rwindow,
2089 		    rmaxpack);
2090 	} else if (strcmp(ctype, "forwarded-streamlocal@openssh.com") == 0) {
2091 		c = client_request_forwarded_streamlocal(ctype, rchan);
2092 	} else if (strcmp(ctype, "x11") == 0) {
2093 		c = client_request_x11(ctype, rchan);
2094 	} else if (strcmp(ctype, "auth-agent@openssh.com") == 0) {
2095 		c = client_request_agent(ctype, rchan);
2096 	}
2097 	if (c != NULL && c->type == SSH_CHANNEL_MUX_CLIENT) {
2098 		debug3("proxied to downstream: %s", ctype);
2099 	} else if (c != NULL) {
2100 		debug("confirm %s", ctype);
2101 		c->remote_id = rchan;
2102 		c->remote_window = rwindow;
2103 		c->remote_maxpacket = rmaxpack;
2104 		if (c->type != SSH_CHANNEL_CONNECTING) {
2105 			packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
2106 			packet_put_int(c->remote_id);
2107 			packet_put_int(c->self);
2108 			packet_put_int(c->local_window);
2109 			packet_put_int(c->local_maxpacket);
2110 			packet_send();
2111 		}
2112 	} else {
2113 		debug("failure %s", ctype);
2114 		packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
2115 		packet_put_int(rchan);
2116 		packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
2117 		if (!(datafellows & SSH_BUG_OPENFAILURE)) {
2118 			packet_put_cstring("open failed");
2119 			packet_put_cstring("");
2120 		}
2121 		packet_send();
2122 	}
2123 	free(ctype);
2124 	return 0;
2125 }
2126 
2127 static int
client_input_channel_req(int type,u_int32_t seq,void * ctxt)2128 client_input_channel_req(int type, u_int32_t seq, void *ctxt)
2129 {
2130 	Channel *c = NULL;
2131 	int exitval, id, reply, success = 0;
2132 	char *rtype;
2133 
2134 	id = packet_get_int();
2135 	c = channel_lookup(id);
2136 	if (channel_proxy_upstream(c, type, seq, ctxt))
2137 		return 0;
2138 	rtype = packet_get_string(NULL);
2139 	reply = packet_get_char();
2140 
2141 	debug("client_input_channel_req: channel %d rtype %s reply %d",
2142 	    id, rtype, reply);
2143 
2144 	if (id == -1) {
2145 		error("client_input_channel_req: request for channel -1");
2146 	} else if (c == NULL) {
2147 		error("client_input_channel_req: channel %d: "
2148 		    "unknown channel", id);
2149 	} else if (strcmp(rtype, "eow@openssh.com") == 0) {
2150 		packet_check_eom();
2151 		chan_rcvd_eow(c);
2152 	} else if (strcmp(rtype, "exit-status") == 0) {
2153 		exitval = packet_get_int();
2154 		if (c->ctl_chan != -1) {
2155 			mux_exit_message(c, exitval);
2156 			success = 1;
2157 		} else if (id == session_ident) {
2158 			/* Record exit value of local session */
2159 			success = 1;
2160 			exit_status = exitval;
2161 		} else {
2162 			/* Probably for a mux channel that has already closed */
2163 			debug("%s: no sink for exit-status on channel %d",
2164 			    __func__, id);
2165 		}
2166 		packet_check_eom();
2167 	}
2168 	if (reply && c != NULL && !(c->flags & CHAN_CLOSE_SENT)) {
2169 		packet_start(success ?
2170 		    SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
2171 		packet_put_int(c->remote_id);
2172 		packet_send();
2173 	}
2174 	free(rtype);
2175 	return 0;
2176 }
2177 
2178 struct hostkeys_update_ctx {
2179 	/* The hostname and (optionally) IP address string for the server */
2180 	char *host_str, *ip_str;
2181 
2182 	/*
2183 	 * Keys received from the server and a flag for each indicating
2184 	 * whether they already exist in known_hosts.
2185 	 * keys_seen is filled in by hostkeys_find() and later (for new
2186 	 * keys) by client_global_hostkeys_private_confirm().
2187 	 */
2188 	struct sshkey **keys;
2189 	int *keys_seen;
2190 	size_t nkeys;
2191 
2192 	size_t nnew;
2193 
2194 	/*
2195 	 * Keys that are in known_hosts, but were not present in the update
2196 	 * from the server (i.e. scheduled to be deleted).
2197 	 * Filled in by hostkeys_find().
2198 	 */
2199 	struct sshkey **old_keys;
2200 	size_t nold;
2201 };
2202 
2203 static void
hostkeys_update_ctx_free(struct hostkeys_update_ctx * ctx)2204 hostkeys_update_ctx_free(struct hostkeys_update_ctx *ctx)
2205 {
2206 	size_t i;
2207 
2208 	if (ctx == NULL)
2209 		return;
2210 	for (i = 0; i < ctx->nkeys; i++)
2211 		sshkey_free(ctx->keys[i]);
2212 	free(ctx->keys);
2213 	free(ctx->keys_seen);
2214 	for (i = 0; i < ctx->nold; i++)
2215 		sshkey_free(ctx->old_keys[i]);
2216 	free(ctx->old_keys);
2217 	free(ctx->host_str);
2218 	free(ctx->ip_str);
2219 	free(ctx);
2220 }
2221 
2222 static int
hostkeys_find(struct hostkey_foreach_line * l,void * _ctx)2223 hostkeys_find(struct hostkey_foreach_line *l, void *_ctx)
2224 {
2225 	struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
2226 	size_t i;
2227 	struct sshkey **tmp;
2228 
2229 	if (l->status != HKF_STATUS_MATCHED || l->key == NULL ||
2230 	    l->key->type == KEY_RSA1)
2231 		return 0;
2232 
2233 	/* Mark off keys we've already seen for this host */
2234 	for (i = 0; i < ctx->nkeys; i++) {
2235 		if (sshkey_equal(l->key, ctx->keys[i])) {
2236 			debug3("%s: found %s key at %s:%ld", __func__,
2237 			    sshkey_ssh_name(ctx->keys[i]), l->path, l->linenum);
2238 			ctx->keys_seen[i] = 1;
2239 			return 0;
2240 		}
2241 	}
2242 	/* This line contained a key that not offered by the server */
2243 	debug3("%s: deprecated %s key at %s:%ld", __func__,
2244 	    sshkey_ssh_name(l->key), l->path, l->linenum);
2245 	if ((tmp = reallocarray(ctx->old_keys, ctx->nold + 1,
2246 	    sizeof(*ctx->old_keys))) == NULL)
2247 		fatal("%s: reallocarray failed nold = %zu",
2248 		    __func__, ctx->nold);
2249 	ctx->old_keys = tmp;
2250 	ctx->old_keys[ctx->nold++] = l->key;
2251 	l->key = NULL;
2252 
2253 	return 0;
2254 }
2255 
2256 static void
update_known_hosts(struct hostkeys_update_ctx * ctx)2257 update_known_hosts(struct hostkeys_update_ctx *ctx)
2258 {
2259 	int r, was_raw = 0;
2260 	int loglevel = options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK ?
2261 	    SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_VERBOSE;
2262 	char *fp, *response;
2263 	size_t i;
2264 
2265 	for (i = 0; i < ctx->nkeys; i++) {
2266 		if (ctx->keys_seen[i] != 2)
2267 			continue;
2268 		if ((fp = sshkey_fingerprint(ctx->keys[i],
2269 		    options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
2270 			fatal("%s: sshkey_fingerprint failed", __func__);
2271 		do_log2(loglevel, "Learned new hostkey: %s %s",
2272 		    sshkey_type(ctx->keys[i]), fp);
2273 		free(fp);
2274 	}
2275 	for (i = 0; i < ctx->nold; i++) {
2276 		if ((fp = sshkey_fingerprint(ctx->old_keys[i],
2277 		    options.fingerprint_hash, SSH_FP_DEFAULT)) == NULL)
2278 			fatal("%s: sshkey_fingerprint failed", __func__);
2279 		do_log2(loglevel, "Deprecating obsolete hostkey: %s %s",
2280 		    sshkey_type(ctx->old_keys[i]), fp);
2281 		free(fp);
2282 	}
2283 	if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK) {
2284 		if (get_saved_tio() != NULL) {
2285 			leave_raw_mode(1);
2286 			was_raw = 1;
2287 		}
2288 		response = NULL;
2289 		for (i = 0; !quit_pending && i < 3; i++) {
2290 			free(response);
2291 			response = read_passphrase("Accept updated hostkeys? "
2292 			    "(yes/no): ", RP_ECHO);
2293 			if (strcasecmp(response, "yes") == 0)
2294 				break;
2295 			else if (quit_pending || response == NULL ||
2296 			    strcasecmp(response, "no") == 0) {
2297 				options.update_hostkeys = 0;
2298 				break;
2299 			} else {
2300 				do_log2(loglevel, "Please enter "
2301 				    "\"yes\" or \"no\"");
2302 			}
2303 		}
2304 		if (quit_pending || i >= 3 || response == NULL)
2305 			options.update_hostkeys = 0;
2306 		free(response);
2307 		if (was_raw)
2308 			enter_raw_mode(1);
2309 	}
2310 
2311 	/*
2312 	 * Now that all the keys are verified, we can go ahead and replace
2313 	 * them in known_hosts (assuming SSH_UPDATE_HOSTKEYS_ASK didn't
2314 	 * cancel the operation).
2315 	 */
2316 	if (options.update_hostkeys != 0 &&
2317 	    (r = hostfile_replace_entries(options.user_hostfiles[0],
2318 	    ctx->host_str, ctx->ip_str, ctx->keys, ctx->nkeys,
2319 	    options.hash_known_hosts, 0,
2320 	    options.fingerprint_hash)) != 0)
2321 		error("%s: hostfile_replace_entries failed: %s",
2322 		    __func__, ssh_err(r));
2323 }
2324 
2325 static void
client_global_hostkeys_private_confirm(int type,u_int32_t seq,void * _ctx)2326 client_global_hostkeys_private_confirm(int type, u_int32_t seq, void *_ctx)
2327 {
2328 	struct ssh *ssh = active_state; /* XXX */
2329 	struct hostkeys_update_ctx *ctx = (struct hostkeys_update_ctx *)_ctx;
2330 	size_t i, ndone;
2331 	struct sshbuf *signdata;
2332 	int r;
2333 	const u_char *sig;
2334 	size_t siglen;
2335 
2336 	if (ctx->nnew == 0)
2337 		fatal("%s: ctx->nnew == 0", __func__); /* sanity */
2338 	if (type != SSH2_MSG_REQUEST_SUCCESS) {
2339 		error("Server failed to confirm ownership of "
2340 		    "private host keys");
2341 		hostkeys_update_ctx_free(ctx);
2342 		return;
2343 	}
2344 	if ((signdata = sshbuf_new()) == NULL)
2345 		fatal("%s: sshbuf_new failed", __func__);
2346 	/* Don't want to accidentally accept an unbound signature */
2347 	if (ssh->kex->session_id_len == 0)
2348 		fatal("%s: ssh->kex->session_id_len == 0", __func__);
2349 	/*
2350 	 * Expect a signature for each of the ctx->nnew private keys we
2351 	 * haven't seen before. They will be in the same order as the
2352 	 * ctx->keys where the corresponding ctx->keys_seen[i] == 0.
2353 	 */
2354 	for (ndone = i = 0; i < ctx->nkeys; i++) {
2355 		if (ctx->keys_seen[i])
2356 			continue;
2357 		/* Prepare data to be signed: session ID, unique string, key */
2358 		sshbuf_reset(signdata);
2359 		if ( (r = sshbuf_put_cstring(signdata,
2360 		    "hostkeys-prove-00@openssh.com")) != 0 ||
2361 		    (r = sshbuf_put_string(signdata, ssh->kex->session_id,
2362 		    ssh->kex->session_id_len)) != 0 ||
2363 		    (r = sshkey_puts(ctx->keys[i], signdata)) != 0)
2364 			fatal("%s: failed to prepare signature: %s",
2365 			    __func__, ssh_err(r));
2366 		/* Extract and verify signature */
2367 		if ((r = sshpkt_get_string_direct(ssh, &sig, &siglen)) != 0) {
2368 			error("%s: couldn't parse message: %s",
2369 			    __func__, ssh_err(r));
2370 			goto out;
2371 		}
2372 		if ((r = sshkey_verify(ctx->keys[i], sig, siglen,
2373 		    sshbuf_ptr(signdata), sshbuf_len(signdata), 0)) != 0) {
2374 			error("%s: server gave bad signature for %s key %zu",
2375 			    __func__, sshkey_type(ctx->keys[i]), i);
2376 			goto out;
2377 		}
2378 		/* Key is good. Mark it as 'seen' */
2379 		ctx->keys_seen[i] = 2;
2380 		ndone++;
2381 	}
2382 	if (ndone != ctx->nnew)
2383 		fatal("%s: ndone != ctx->nnew (%zu / %zu)", __func__,
2384 		    ndone, ctx->nnew);  /* Shouldn't happen */
2385 	ssh_packet_check_eom(ssh);
2386 
2387 	/* Make the edits to known_hosts */
2388 	update_known_hosts(ctx);
2389  out:
2390 	hostkeys_update_ctx_free(ctx);
2391 }
2392 
2393 /*
2394  * Returns non-zero if the key is accepted by HostkeyAlgorithms.
2395  * Made slightly less trivial by the multiple RSA signature algorithm names.
2396  */
2397 static int
key_accepted_by_hostkeyalgs(const struct sshkey * key)2398 key_accepted_by_hostkeyalgs(const struct sshkey *key)
2399 {
2400 	const char *ktype = sshkey_ssh_name(key);
2401 	const char *hostkeyalgs = options.hostkeyalgorithms != NULL ?
2402 	    options.hostkeyalgorithms : KEX_DEFAULT_PK_ALG;
2403 
2404 	if (key == NULL || key->type == KEY_UNSPEC)
2405 		return 0;
2406 	if (key->type == KEY_RSA &&
2407 	    (match_pattern_list("rsa-sha2-256", hostkeyalgs, 0) == 1 ||
2408 	    match_pattern_list("rsa-sha2-512", hostkeyalgs, 0) == 1))
2409 		return 1;
2410 	return match_pattern_list(ktype, hostkeyalgs, 0) == 1;
2411 }
2412 
2413 /*
2414  * Handle hostkeys-00@openssh.com global request to inform the client of all
2415  * the server's hostkeys. The keys are checked against the user's
2416  * HostkeyAlgorithms preference before they are accepted.
2417  */
2418 static int
client_input_hostkeys(void)2419 client_input_hostkeys(void)
2420 {
2421 	struct ssh *ssh = active_state; /* XXX */
2422 	const u_char *blob = NULL;
2423 	size_t i, len = 0;
2424 	struct sshbuf *buf = NULL;
2425 	struct sshkey *key = NULL, **tmp;
2426 	int r;
2427 	char *fp;
2428 	static int hostkeys_seen = 0; /* XXX use struct ssh */
2429 	extern struct sockaddr_storage hostaddr; /* XXX from ssh.c */
2430 	struct hostkeys_update_ctx *ctx = NULL;
2431 
2432 	if (hostkeys_seen)
2433 		fatal("%s: server already sent hostkeys", __func__);
2434 	if (options.update_hostkeys == SSH_UPDATE_HOSTKEYS_ASK &&
2435 	    options.batch_mode)
2436 		return 1; /* won't ask in batchmode, so don't even try */
2437 	if (!options.update_hostkeys || options.num_user_hostfiles <= 0)
2438 		return 1;
2439 
2440 	ctx = xcalloc(1, sizeof(*ctx));
2441 	while (ssh_packet_remaining(ssh) > 0) {
2442 		sshkey_free(key);
2443 		key = NULL;
2444 		if ((r = sshpkt_get_string_direct(ssh, &blob, &len)) != 0) {
2445 			error("%s: couldn't parse message: %s",
2446 			    __func__, ssh_err(r));
2447 			goto out;
2448 		}
2449 		if ((r = sshkey_from_blob(blob, len, &key)) != 0) {
2450 			error("%s: parse key: %s", __func__, ssh_err(r));
2451 			goto out;
2452 		}
2453 		fp = sshkey_fingerprint(key, options.fingerprint_hash,
2454 		    SSH_FP_DEFAULT);
2455 		debug3("%s: received %s key %s", __func__,
2456 		    sshkey_type(key), fp);
2457 		free(fp);
2458 
2459 		if (!key_accepted_by_hostkeyalgs(key)) {
2460 			debug3("%s: %s key not permitted by HostkeyAlgorithms",
2461 			    __func__, sshkey_ssh_name(key));
2462 			continue;
2463 		}
2464 		/* Skip certs */
2465 		if (sshkey_is_cert(key)) {
2466 			debug3("%s: %s key is a certificate; skipping",
2467 			    __func__, sshkey_ssh_name(key));
2468 			continue;
2469 		}
2470 		/* Ensure keys are unique */
2471 		for (i = 0; i < ctx->nkeys; i++) {
2472 			if (sshkey_equal(key, ctx->keys[i])) {
2473 				error("%s: received duplicated %s host key",
2474 				    __func__, sshkey_ssh_name(key));
2475 				goto out;
2476 			}
2477 		}
2478 		/* Key is good, record it */
2479 		if ((tmp = reallocarray(ctx->keys, ctx->nkeys + 1,
2480 		    sizeof(*ctx->keys))) == NULL)
2481 			fatal("%s: reallocarray failed nkeys = %zu",
2482 			    __func__, ctx->nkeys);
2483 		ctx->keys = tmp;
2484 		ctx->keys[ctx->nkeys++] = key;
2485 		key = NULL;
2486 	}
2487 
2488 	if (ctx->nkeys == 0) {
2489 		debug("%s: server sent no hostkeys", __func__);
2490 		goto out;
2491 	}
2492 
2493 	if ((ctx->keys_seen = calloc(ctx->nkeys,
2494 	    sizeof(*ctx->keys_seen))) == NULL)
2495 		fatal("%s: calloc failed", __func__);
2496 
2497 	get_hostfile_hostname_ipaddr(host,
2498 	    options.check_host_ip ? (struct sockaddr *)&hostaddr : NULL,
2499 	    options.port, &ctx->host_str,
2500 	    options.check_host_ip ? &ctx->ip_str : NULL);
2501 
2502 	/* Find which keys we already know about. */
2503 	if ((r = hostkeys_foreach(options.user_hostfiles[0], hostkeys_find,
2504 	    ctx, ctx->host_str, ctx->ip_str,
2505 	    HKF_WANT_PARSE_KEY|HKF_WANT_MATCH)) != 0) {
2506 		error("%s: hostkeys_foreach failed: %s", __func__, ssh_err(r));
2507 		goto out;
2508 	}
2509 
2510 	/* Figure out if we have any new keys to add */
2511 	ctx->nnew = 0;
2512 	for (i = 0; i < ctx->nkeys; i++) {
2513 		if (!ctx->keys_seen[i])
2514 			ctx->nnew++;
2515 	}
2516 
2517 	debug3("%s: %zu keys from server: %zu new, %zu retained. %zu to remove",
2518 	    __func__, ctx->nkeys, ctx->nnew, ctx->nkeys - ctx->nnew, ctx->nold);
2519 
2520 	if (ctx->nnew == 0 && ctx->nold != 0) {
2521 		/* We have some keys to remove. Just do it. */
2522 		update_known_hosts(ctx);
2523 	} else if (ctx->nnew != 0) {
2524 		/*
2525 		 * We have received hitherto-unseen keys from the server.
2526 		 * Ask the server to confirm ownership of the private halves.
2527 		 */
2528 		debug3("%s: asking server to prove ownership for %zu keys",
2529 		    __func__, ctx->nnew);
2530 		if ((r = sshpkt_start(ssh, SSH2_MSG_GLOBAL_REQUEST)) != 0 ||
2531 		    (r = sshpkt_put_cstring(ssh,
2532 		    "hostkeys-prove-00@openssh.com")) != 0 ||
2533 		    (r = sshpkt_put_u8(ssh, 1)) != 0) /* bool: want reply */
2534 			fatal("%s: cannot prepare packet: %s",
2535 			    __func__, ssh_err(r));
2536 		if ((buf = sshbuf_new()) == NULL)
2537 			fatal("%s: sshbuf_new", __func__);
2538 		for (i = 0; i < ctx->nkeys; i++) {
2539 			if (ctx->keys_seen[i])
2540 				continue;
2541 			sshbuf_reset(buf);
2542 			if ((r = sshkey_putb(ctx->keys[i], buf)) != 0)
2543 				fatal("%s: sshkey_putb: %s",
2544 				    __func__, ssh_err(r));
2545 			if ((r = sshpkt_put_stringb(ssh, buf)) != 0)
2546 				fatal("%s: sshpkt_put_string: %s",
2547 				    __func__, ssh_err(r));
2548 		}
2549 		if ((r = sshpkt_send(ssh)) != 0)
2550 			fatal("%s: sshpkt_send: %s", __func__, ssh_err(r));
2551 		client_register_global_confirm(
2552 		    client_global_hostkeys_private_confirm, ctx);
2553 		ctx = NULL;  /* will be freed in callback */
2554 	}
2555 
2556 	/* Success */
2557  out:
2558 	hostkeys_update_ctx_free(ctx);
2559 	sshkey_free(key);
2560 	sshbuf_free(buf);
2561 	/*
2562 	 * NB. Return success for all cases. The server doesn't need to know
2563 	 * what the client does with its hosts file.
2564 	 */
2565 	return 1;
2566 }
2567 
2568 static int
client_input_global_request(int type,u_int32_t seq,void * ctxt)2569 client_input_global_request(int type, u_int32_t seq, void *ctxt)
2570 {
2571 	char *rtype;
2572 	int want_reply;
2573 	int success = 0;
2574 
2575 	rtype = packet_get_cstring(NULL);
2576 	want_reply = packet_get_char();
2577 	debug("client_input_global_request: rtype %s want_reply %d",
2578 	    rtype, want_reply);
2579 	if (strcmp(rtype, "hostkeys-00@openssh.com") == 0)
2580 		success = client_input_hostkeys();
2581 	if (want_reply) {
2582 		packet_start(success ?
2583 		    SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
2584 		packet_send();
2585 		packet_write_wait();
2586 	}
2587 	free(rtype);
2588 	return 0;
2589 }
2590 
2591 void
client_session2_setup(int id,int want_tty,int want_subsystem,const char * term,struct termios * tiop,int in_fd,Buffer * cmd,char ** env)2592 client_session2_setup(int id, int want_tty, int want_subsystem,
2593     const char *term, struct termios *tiop, int in_fd, Buffer *cmd, char **env)
2594 {
2595 	int len;
2596 	Channel *c = NULL;
2597 
2598 	debug2("%s: id %d", __func__, id);
2599 
2600 	if ((c = channel_lookup(id)) == NULL)
2601 		fatal("client_session2_setup: channel %d: unknown channel", id);
2602 
2603 	packet_set_interactive(want_tty,
2604 	    options.ip_qos_interactive, options.ip_qos_bulk);
2605 
2606 	if (want_tty) {
2607 		struct winsize ws;
2608 
2609 		/* Store window size in the packet. */
2610 		if (ioctl(in_fd, TIOCGWINSZ, &ws) < 0)
2611 			memset(&ws, 0, sizeof(ws));
2612 
2613 		channel_request_start(id, "pty-req", 1);
2614 		client_expect_confirm(id, "PTY allocation", CONFIRM_TTY);
2615 		packet_put_cstring(term != NULL ? term : "");
2616 		packet_put_int((u_int)ws.ws_col);
2617 		packet_put_int((u_int)ws.ws_row);
2618 		packet_put_int((u_int)ws.ws_xpixel);
2619 		packet_put_int((u_int)ws.ws_ypixel);
2620 		if (tiop == NULL)
2621 			tiop = get_saved_tio();
2622 		tty_make_modes(-1, tiop);
2623 		packet_send();
2624 		/* XXX wait for reply */
2625 		c->client_tty = 1;
2626 	}
2627 
2628 	/* Transfer any environment variables from client to server */
2629 	if (options.num_send_env != 0 && env != NULL) {
2630 		int i, j, matched;
2631 		char *name, *val;
2632 
2633 		debug("Sending environment.");
2634 		for (i = 0; env[i] != NULL; i++) {
2635 			/* Split */
2636 			name = xstrdup(env[i]);
2637 			if ((val = strchr(name, '=')) == NULL) {
2638 				free(name);
2639 				continue;
2640 			}
2641 			*val++ = '\0';
2642 
2643 			matched = 0;
2644 			for (j = 0; j < options.num_send_env; j++) {
2645 				if (match_pattern(name, options.send_env[j])) {
2646 					matched = 1;
2647 					break;
2648 				}
2649 			}
2650 			if (!matched) {
2651 				debug3("Ignored env %s", name);
2652 				free(name);
2653 				continue;
2654 			}
2655 
2656 			debug("Sending env %s = %s", name, val);
2657 			channel_request_start(id, "env", 0);
2658 			packet_put_cstring(name);
2659 			packet_put_cstring(val);
2660 			packet_send();
2661 			free(name);
2662 		}
2663 	}
2664 
2665 	len = buffer_len(cmd);
2666 	if (len > 0) {
2667 		if (len > 900)
2668 			len = 900;
2669 		if (want_subsystem) {
2670 			debug("Sending subsystem: %.*s",
2671 			    len, (u_char*)buffer_ptr(cmd));
2672 			channel_request_start(id, "subsystem", 1);
2673 			client_expect_confirm(id, "subsystem", CONFIRM_CLOSE);
2674 		} else {
2675 			debug("Sending command: %.*s",
2676 			    len, (u_char*)buffer_ptr(cmd));
2677 			channel_request_start(id, "exec", 1);
2678 			client_expect_confirm(id, "exec", CONFIRM_CLOSE);
2679 		}
2680 		packet_put_string(buffer_ptr(cmd), buffer_len(cmd));
2681 		packet_send();
2682 	} else {
2683 		channel_request_start(id, "shell", 1);
2684 		client_expect_confirm(id, "shell", CONFIRM_CLOSE);
2685 		packet_send();
2686 	}
2687 }
2688 
2689 static void
client_init_dispatch_20(void)2690 client_init_dispatch_20(void)
2691 {
2692 	dispatch_init(&dispatch_protocol_error);
2693 
2694 	dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
2695 	dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
2696 	dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
2697 	dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
2698 	dispatch_set(SSH2_MSG_CHANNEL_OPEN, &client_input_channel_open);
2699 	dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
2700 	dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
2701 	dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &client_input_channel_req);
2702 	dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
2703 	dispatch_set(SSH2_MSG_CHANNEL_SUCCESS, &channel_input_status_confirm);
2704 	dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &channel_input_status_confirm);
2705 	dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &client_input_global_request);
2706 
2707 	/* rekeying */
2708 	dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
2709 
2710 	/* global request reply messages */
2711 	dispatch_set(SSH2_MSG_REQUEST_FAILURE, &client_global_request_reply);
2712 	dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &client_global_request_reply);
2713 }
2714 
2715 static void
client_init_dispatch_13(void)2716 client_init_dispatch_13(void)
2717 {
2718 	dispatch_init(NULL);
2719 	dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
2720 	dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
2721 	dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
2722 	dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
2723 	dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
2724 	dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
2725 	dispatch_set(SSH_SMSG_EXITSTATUS, &client_input_exit_status);
2726 	dispatch_set(SSH_SMSG_STDERR_DATA, &client_input_stderr_data);
2727 	dispatch_set(SSH_SMSG_STDOUT_DATA, &client_input_stdout_data);
2728 
2729 	dispatch_set(SSH_SMSG_AGENT_OPEN, options.forward_agent ?
2730 	    &client_input_agent_open : &deny_input_open);
2731 	dispatch_set(SSH_SMSG_X11_OPEN, options.forward_x11 ?
2732 	    &x11_input_open : &deny_input_open);
2733 }
2734 
2735 static void
client_init_dispatch_15(void)2736 client_init_dispatch_15(void)
2737 {
2738 	client_init_dispatch_13();
2739 	dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
2740 	dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, & channel_input_oclose);
2741 }
2742 
2743 static void
client_init_dispatch(void)2744 client_init_dispatch(void)
2745 {
2746 	if (compat20)
2747 		client_init_dispatch_20();
2748 	else if (compat13)
2749 		client_init_dispatch_13();
2750 	else
2751 		client_init_dispatch_15();
2752 }
2753 
2754 void
client_stop_mux(void)2755 client_stop_mux(void)
2756 {
2757 	if (options.control_path != NULL && muxserver_sock != -1)
2758 		unlink(options.control_path);
2759 	/*
2760 	 * If we are in persist mode, or don't have a shell, signal that we
2761 	 * should close when all active channels are closed.
2762 	 */
2763 	if (options.control_persist || no_shell_flag) {
2764 		session_closed = 1;
2765 		setproctitle("[stopped mux]");
2766 	}
2767 }
2768 
2769 /* client specific fatal cleanup */
2770 void
cleanup_exit(int i)2771 cleanup_exit(int i)
2772 {
2773 	leave_raw_mode(options.request_tty == REQUEST_TTY_FORCE);
2774 	leave_non_blocking();
2775 	if (options.control_path != NULL && muxserver_sock != -1)
2776 		unlink(options.control_path);
2777 	ssh_kill_proxy_command();
2778 	_exit(i);
2779 }
2780