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240debe0 1/* $OpenBSD: serverloop.c,v 1.145 2006/10/11 12:38:03 markus Exp $ */
3c0ef626 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 * Server main loop for handling the interactive session.
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 * SSH2 support by Markus Friedl.
15 * Copyright (c) 2000, 2001 Markus Friedl. 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#include "includes.h"
30460aeb 39
40#include <sys/types.h>
41#include <sys/param.h>
42#include <sys/wait.h>
43#include <sys/socket.h>
44#ifdef HAVE_SYS_TIME_H
45# include <sys/time.h>
46#endif
47
48#include <netinet/in.h>
49
50#include <errno.h>
51#include <fcntl.h>
52#include <pwd.h>
53#include <signal.h>
54#include <string.h>
55#include <termios.h>
56#include <unistd.h>
57#include <stdarg.h>
3c0ef626 58
59#include "xmalloc.h"
60#include "packet.h"
61#include "buffer.h"
62#include "log.h"
63#include "servconf.h"
473db5ab 64#include "canohost.h"
3c0ef626 65#include "sshpty.h"
66#include "channels.h"
67#include "compat.h"
68#include "ssh1.h"
69#include "ssh2.h"
30460aeb 70#include "key.h"
71#include "cipher.h"
72#include "kex.h"
73#include "hostfile.h"
3c0ef626 74#include "auth.h"
75#include "session.h"
76#include "dispatch.h"
77#include "auth-options.h"
78#include "serverloop.h"
79#include "misc.h"
3c0ef626 80
81extern ServerOptions options;
82
83/* XXX */
84extern Kex *xxx_kex;
473db5ab 85extern Authctxt *the_authctxt;
08822d99 86extern int use_privsep;
3c0ef626 87
88static Buffer stdin_buffer; /* Buffer for stdin data. */
89static Buffer stdout_buffer; /* Buffer for stdout data. */
90static Buffer stderr_buffer; /* Buffer for stderr data. */
91static int fdin; /* Descriptor for stdin (for writing) */
92static int fdout; /* Descriptor for stdout (for reading);
93 May be same number as fdin. */
94static int fderr; /* Descriptor for stderr. May be -1. */
95static long stdin_bytes = 0; /* Number of bytes written to stdin. */
96static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */
97static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */
98static long fdout_bytes = 0; /* Number of stdout bytes read from program. */
99static int stdin_eof = 0; /* EOF message received from client. */
100static int fdout_eof = 0; /* EOF encountered reading from fdout. */
101static int fderr_eof = 0; /* EOF encountered readung from fderr. */
102static int fdin_is_tty = 0; /* fdin points to a tty. */
103static int connection_in; /* Connection to client (input). */
104static int connection_out; /* Connection to client (output). */
105static int connection_closed = 0; /* Connection to client closed. */
106static u_int buffer_high; /* "Soft" max buffer size. */
107static int client_alive_timeouts = 0;
108
109/*
110 * This SIGCHLD kludge is used to detect when the child exits. The server
111 * will exit after that, as soon as forwarded connections have terminated.
112 */
113
473db5ab 114static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */
3c0ef626 115
08822d99 116/* Cleanup on signals (!use_privsep case only) */
117static volatile sig_atomic_t received_sigterm = 0;
118
3c0ef626 119/* prototypes */
120static void server_init_dispatch(void);
121
473db5ab 122/*
123 * we write to this pipe if a SIGCHLD is caught in order to avoid
124 * the race between select() and child_terminated
125 */
126static int notify_pipe[2];
127static void
128notify_setup(void)
129{
130 if (pipe(notify_pipe) < 0) {
131 error("pipe(notify_pipe) failed %s", strerror(errno));
132 } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) ||
133 (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) {
134 error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno));
135 close(notify_pipe[0]);
136 close(notify_pipe[1]);
137 } else {
138 set_nonblock(notify_pipe[0]);
139 set_nonblock(notify_pipe[1]);
140 return;
141 }
142 notify_pipe[0] = -1; /* read end */
143 notify_pipe[1] = -1; /* write end */
144}
145static void
146notify_parent(void)
147{
148 if (notify_pipe[1] != -1)
149 write(notify_pipe[1], "", 1);
150}
151static void
152notify_prepare(fd_set *readset)
153{
154 if (notify_pipe[0] != -1)
155 FD_SET(notify_pipe[0], readset);
156}
157static void
158notify_done(fd_set *readset)
159{
160 char c;
161
162 if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset))
163 while (read(notify_pipe[0], &c, 1) != -1)
164 debug2("notify_done: reading");
165}
166
30460aeb 167/*ARGSUSED*/
3c0ef626 168static void
169sigchld_handler(int sig)
170{
171 int save_errno = errno;
3c0ef626 172 child_terminated = 1;
473db5ab 173#ifndef _UNICOS
3c0ef626 174 mysignal(SIGCHLD, sigchld_handler);
473db5ab 175#endif
176 notify_parent();
3c0ef626 177 errno = save_errno;
178}
179
30460aeb 180/*ARGSUSED*/
08822d99 181static void
182sigterm_handler(int sig)
183{
184 received_sigterm = sig;
185}
186
3c0ef626 187/*
188 * Make packets from buffered stderr data, and buffer it for sending
189 * to the client.
190 */
191static void
192make_packets_from_stderr_data(void)
193{
473db5ab 194 u_int len;
3c0ef626 195
196 /* Send buffered stderr data to the client. */
197 while (buffer_len(&stderr_buffer) > 0 &&
198 packet_not_very_much_data_to_write()) {
199 len = buffer_len(&stderr_buffer);
200 if (packet_is_interactive()) {
201 if (len > 512)
202 len = 512;
203 } else {
204 /* Keep the packets at reasonable size. */
205 if (len > packet_get_maxsize())
206 len = packet_get_maxsize();
207 }
208 packet_start(SSH_SMSG_STDERR_DATA);
209 packet_put_string(buffer_ptr(&stderr_buffer), len);
210 packet_send();
211 buffer_consume(&stderr_buffer, len);
212 stderr_bytes += len;
213 }
214}
215
216/*
217 * Make packets from buffered stdout data, and buffer it for sending to the
218 * client.
219 */
220static void
221make_packets_from_stdout_data(void)
222{
473db5ab 223 u_int len;
3c0ef626 224
225 /* Send buffered stdout data to the client. */
226 while (buffer_len(&stdout_buffer) > 0 &&
227 packet_not_very_much_data_to_write()) {
228 len = buffer_len(&stdout_buffer);
229 if (packet_is_interactive()) {
230 if (len > 512)
231 len = 512;
232 } else {
233 /* Keep the packets at reasonable size. */
234 if (len > packet_get_maxsize())
235 len = packet_get_maxsize();
236 }
237 packet_start(SSH_SMSG_STDOUT_DATA);
238 packet_put_string(buffer_ptr(&stdout_buffer), len);
239 packet_send();
240 buffer_consume(&stdout_buffer, len);
241 stdout_bytes += len;
242 }
243}
244
245static void
246client_alive_check(void)
247{
473db5ab 248 int channel_id;
3c0ef626 249
250 /* timeout, check to see how many we have had */
240debe0 251 if (++client_alive_timeouts > options.client_alive_count_max) {
252 logit("Timeout, client not responding.");
253 cleanup_exit(255);
254 }
3c0ef626 255
3c0ef626 256 /*
473db5ab 257 * send a bogus global/channel request with "wantreply",
3c0ef626 258 * we should get back a failure
259 */
473db5ab 260 if ((channel_id = channel_find_open()) == -1) {
261 packet_start(SSH2_MSG_GLOBAL_REQUEST);
262 packet_put_cstring("keepalive@openssh.com");
263 packet_put_char(1); /* boolean: want reply */
264 } else {
265 channel_request_start(channel_id, "keepalive@openssh.com", 1);
266 }
3c0ef626 267 packet_send();
268}
269
270/*
271 * Sleep in select() until we can do something. This will initialize the
272 * select masks. Upon return, the masks will indicate which descriptors
273 * have data or can accept data. Optionally, a maximum time can be specified
274 * for the duration of the wait (0 = infinite).
275 */
276static void
277wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
473db5ab 278 u_int *nallocp, u_int max_time_milliseconds)
3c0ef626 279{
280 struct timeval tv, *tvp;
281 int ret;
282 int client_alive_scheduled = 0;
0b90ac93 283 int program_alive_scheduled = 0;
3c0ef626 284
285 /*
473db5ab 286 * if using client_alive, set the max timeout accordingly,
3c0ef626 287 * and indicate that this particular timeout was for client
288 * alive by setting the client_alive_scheduled flag.
289 *
290 * this could be randomized somewhat to make traffic
473db5ab 291 * analysis more difficult, but we're not doing it yet.
3c0ef626 292 */
293 if (compat20 &&
294 max_time_milliseconds == 0 && options.client_alive_interval) {
295 client_alive_scheduled = 1;
296 max_time_milliseconds = options.client_alive_interval * 1000;
297 }
298
299 /* Allocate and update select() masks for channel descriptors. */
300 channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0);
301
302 if (compat20) {
303#if 0
304 /* wrong: bad condition XXX */
305 if (channel_not_very_much_buffered_data())
306#endif
307 FD_SET(connection_in, *readsetp);
308 } else {
309 /*
310 * Read packets from the client unless we have too much
311 * buffered stdin or channel data.
312 */
313 if (buffer_len(&stdin_buffer) < buffer_high &&
314 channel_not_very_much_buffered_data())
315 FD_SET(connection_in, *readsetp);
316 /*
317 * If there is not too much data already buffered going to
318 * the client, try to get some more data from the program.
319 */
320 if (packet_not_very_much_data_to_write()) {
0b90ac93 321 program_alive_scheduled = child_terminated;
3c0ef626 322 if (!fdout_eof)
323 FD_SET(fdout, *readsetp);
324 if (!fderr_eof)
325 FD_SET(fderr, *readsetp);
326 }
327 /*
328 * If we have buffered data, try to write some of that data
329 * to the program.
330 */
331 if (fdin != -1 && buffer_len(&stdin_buffer) > 0)
332 FD_SET(fdin, *writesetp);
333 }
473db5ab 334 notify_prepare(*readsetp);
3c0ef626 335
336 /*
337 * If we have buffered packet data going to the client, mark that
338 * descriptor.
339 */
340 if (packet_have_data_to_write())
341 FD_SET(connection_out, *writesetp);
342
343 /*
344 * If child has terminated and there is enough buffer space to read
345 * from it, then read as much as is available and exit.
346 */
347 if (child_terminated && packet_not_very_much_data_to_write())
348 if (max_time_milliseconds == 0 || client_alive_scheduled)
349 max_time_milliseconds = 100;
350
351 if (max_time_milliseconds == 0)
352 tvp = NULL;
353 else {
354 tv.tv_sec = max_time_milliseconds / 1000;
355 tv.tv_usec = 1000 * (max_time_milliseconds % 1000);
356 tvp = &tv;
357 }
3c0ef626 358
359 /* Wait for something to happen, or the timeout to expire. */
360 ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp);
361
362 if (ret == -1) {
363 memset(*readsetp, 0, *nallocp);
364 memset(*writesetp, 0, *nallocp);
365 if (errno != EINTR)
366 error("select: %.100s", strerror(errno));
0b90ac93 367 } else {
368 if (ret == 0 && client_alive_scheduled)
369 client_alive_check();
370 if (!compat20 && program_alive_scheduled && fdin_is_tty) {
371 if (!fdout_eof)
372 FD_SET(fdout, *readsetp);
373 if (!fderr_eof)
374 FD_SET(fderr, *readsetp);
375 }
376 }
473db5ab 377
378 notify_done(*readsetp);
3c0ef626 379}
380
381/*
382 * Processes input from the client and the program. Input data is stored
383 * in buffers and processed later.
384 */
385static void
30460aeb 386process_input(fd_set *readset)
3c0ef626 387{
388 int len;
389 char buf[16384];
390
391 /* Read and buffer any input data from the client. */
392 if (FD_ISSET(connection_in, readset)) {
393 len = read(connection_in, buf, sizeof(buf));
394 if (len == 0) {
473db5ab 395 verbose("Connection closed by %.100s",
396 get_remote_ipaddr());
3c0ef626 397 connection_closed = 1;
398 if (compat20)
399 return;
473db5ab 400 cleanup_exit(255);
3c0ef626 401 } else if (len < 0) {
402 if (errno != EINTR && errno != EAGAIN) {
473db5ab 403 verbose("Read error from remote host "
404 "%.100s: %.100s",
405 get_remote_ipaddr(), strerror(errno));
406 cleanup_exit(255);
3c0ef626 407 }
408 } else {
409 /* Buffer any received data. */
410 packet_process_incoming(buf, len);
411 }
412 }
413 if (compat20)
414 return;
415
416 /* Read and buffer any available stdout data from the program. */
417 if (!fdout_eof && FD_ISSET(fdout, readset)) {
30460aeb 418 errno = 0;
3c0ef626 419 len = read(fdout, buf, sizeof(buf));
0b90ac93 420 if (len < 0 && (errno == EINTR ||
421 (errno == EAGAIN && !child_terminated))) {
3c0ef626 422 /* do nothing */
30460aeb 423#ifndef PTY_ZEROREAD
3c0ef626 424 } else if (len <= 0) {
30460aeb 425#else
426 } else if ((!isatty(fdout) && len <= 0) ||
427 (isatty(fdout) && (len < 0 || (len == 0 && errno != 0)))) {
428#endif
3c0ef626 429 fdout_eof = 1;
430 } else {
431 buffer_append(&stdout_buffer, buf, len);
432 fdout_bytes += len;
433 }
434 }
435 /* Read and buffer any available stderr data from the program. */
436 if (!fderr_eof && FD_ISSET(fderr, readset)) {
30460aeb 437 errno = 0;
3c0ef626 438 len = read(fderr, buf, sizeof(buf));
0b90ac93 439 if (len < 0 && (errno == EINTR ||
440 (errno == EAGAIN && !child_terminated))) {
3c0ef626 441 /* do nothing */
30460aeb 442#ifndef PTY_ZEROREAD
3c0ef626 443 } else if (len <= 0) {
30460aeb 444#else
445 } else if ((!isatty(fderr) && len <= 0) ||
446 (isatty(fderr) && (len < 0 || (len == 0 && errno != 0)))) {
447#endif
3c0ef626 448 fderr_eof = 1;
449 } else {
450 buffer_append(&stderr_buffer, buf, len);
451 }
452 }
453}
454
455/*
456 * Sends data from internal buffers to client program stdin.
457 */
458static void
30460aeb 459process_output(fd_set *writeset)
3c0ef626 460{
461 struct termios tio;
462 u_char *data;
463 u_int dlen;
464 int len;
465
466 /* Write buffered data to program stdin. */
467 if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) {
468 data = buffer_ptr(&stdin_buffer);
469 dlen = buffer_len(&stdin_buffer);
470 len = write(fdin, data, dlen);
471 if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
472 /* do nothing */
473 } else if (len <= 0) {
3c0ef626 474 if (fdin != fdout)
475 close(fdin);
476 else
477 shutdown(fdin, SHUT_WR); /* We will no longer send. */
3c0ef626 478 fdin = -1;
479 } else {
480 /* Successful write. */
481 if (fdin_is_tty && dlen >= 1 && data[0] != '\r' &&
482 tcgetattr(fdin, &tio) == 0 &&
483 !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) {
484 /*
485 * Simulate echo to reduce the impact of
486 * traffic analysis
487 */
488 packet_send_ignore(len);
489 packet_send();
490 }
491 /* Consume the data from the buffer. */
492 buffer_consume(&stdin_buffer, len);
493 /* Update the count of bytes written to the program. */
494 stdin_bytes += len;
495 }
496 }
497 /* Send any buffered packet data to the client. */
498 if (FD_ISSET(connection_out, writeset))
499 packet_write_poll();
500}
501
502/*
503 * Wait until all buffered output has been sent to the client.
504 * This is used when the program terminates.
505 */
506static void
507drain_output(void)
508{
509 /* Send any buffered stdout data to the client. */
510 if (buffer_len(&stdout_buffer) > 0) {
511 packet_start(SSH_SMSG_STDOUT_DATA);
512 packet_put_string(buffer_ptr(&stdout_buffer),
513 buffer_len(&stdout_buffer));
514 packet_send();
515 /* Update the count of sent bytes. */
516 stdout_bytes += buffer_len(&stdout_buffer);
517 }
518 /* Send any buffered stderr data to the client. */
519 if (buffer_len(&stderr_buffer) > 0) {
520 packet_start(SSH_SMSG_STDERR_DATA);
521 packet_put_string(buffer_ptr(&stderr_buffer),
522 buffer_len(&stderr_buffer));
523 packet_send();
524 /* Update the count of sent bytes. */
525 stderr_bytes += buffer_len(&stderr_buffer);
526 }
527 /* Wait until all buffered data has been written to the client. */
528 packet_write_wait();
529}
530
531static void
532process_buffered_input_packets(void)
533{
534 dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL);
535}
536
537/*
538 * Performs the interactive session. This handles data transmission between
539 * the client and the program. Note that the notion of stdin, stdout, and
540 * stderr in this function is sort of reversed: this function writes to
541 * stdin (of the child program), and reads from stdout and stderr (of the
542 * child program).
543 */
544void
545server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg)
546{
547 fd_set *readset = NULL, *writeset = NULL;
473db5ab 548 int max_fd = 0;
549 u_int nalloc = 0;
3c0ef626 550 int wait_status; /* Status returned by wait(). */
551 pid_t wait_pid; /* pid returned by wait(). */
552 int waiting_termination = 0; /* Have displayed waiting close message. */
553 u_int max_time_milliseconds;
554 u_int previous_stdout_buffer_bytes;
555 u_int stdout_buffer_bytes;
556 int type;
557
558 debug("Entering interactive session.");
559
560 /* Initialize the SIGCHLD kludge. */
561 child_terminated = 0;
562 mysignal(SIGCHLD, sigchld_handler);
563
08822d99 564 if (!use_privsep) {
565 signal(SIGTERM, sigterm_handler);
566 signal(SIGINT, sigterm_handler);
567 signal(SIGQUIT, sigterm_handler);
568 }
569
3c0ef626 570 /* Initialize our global variables. */
571 fdin = fdin_arg;
572 fdout = fdout_arg;
573 fderr = fderr_arg;
574
575 /* nonblocking IO */
576 set_nonblock(fdin);
577 set_nonblock(fdout);
578 /* we don't have stderr for interactive terminal sessions, see below */
579 if (fderr != -1)
580 set_nonblock(fderr);
581
582 if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin))
583 fdin_is_tty = 1;
584
585 connection_in = packet_get_connection_in();
586 connection_out = packet_get_connection_out();
587
473db5ab 588 notify_setup();
589
3c0ef626 590 previous_stdout_buffer_bytes = 0;
591
592 /* Set approximate I/O buffer size. */
593 if (packet_is_interactive())
594 buffer_high = 4096;
595 else
596 buffer_high = 64 * 1024;
597
598#if 0
599 /* Initialize max_fd to the maximum of the known file descriptors. */
600 max_fd = MAX(connection_in, connection_out);
601 max_fd = MAX(max_fd, fdin);
602 max_fd = MAX(max_fd, fdout);
603 if (fderr != -1)
604 max_fd = MAX(max_fd, fderr);
605#endif
606
607 /* Initialize Initialize buffers. */
608 buffer_init(&stdin_buffer);
609 buffer_init(&stdout_buffer);
610 buffer_init(&stderr_buffer);
611
612 /*
613 * If we have no separate fderr (which is the case when we have a pty
614 * - there we cannot make difference between data sent to stdout and
615 * stderr), indicate that we have seen an EOF from stderr. This way
08822d99 616 * we don't need to check the descriptor everywhere.
3c0ef626 617 */
618 if (fderr == -1)
619 fderr_eof = 1;
620
621 server_init_dispatch();
622
623 /* Main loop of the server for the interactive session mode. */
624 for (;;) {
625
626 /* Process buffered packets from the client. */
627 process_buffered_input_packets();
628
629 /*
630 * If we have received eof, and there is no more pending
631 * input data, cause a real eof by closing fdin.
632 */
633 if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) {
3c0ef626 634 if (fdin != fdout)
635 close(fdin);
636 else
637 shutdown(fdin, SHUT_WR); /* We will no longer send. */
3c0ef626 638 fdin = -1;
639 }
640 /* Make packets from buffered stderr data to send to the client. */
641 make_packets_from_stderr_data();
642
643 /*
644 * Make packets from buffered stdout data to send to the
645 * client. If there is very little to send, this arranges to
646 * not send them now, but to wait a short while to see if we
647 * are getting more data. This is necessary, as some systems
648 * wake up readers from a pty after each separate character.
649 */
650 max_time_milliseconds = 0;
651 stdout_buffer_bytes = buffer_len(&stdout_buffer);
652 if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 &&
653 stdout_buffer_bytes != previous_stdout_buffer_bytes) {
654 /* try again after a while */
655 max_time_milliseconds = 10;
656 } else {
657 /* Send it now. */
658 make_packets_from_stdout_data();
659 }
660 previous_stdout_buffer_bytes = buffer_len(&stdout_buffer);
661
662 /* Send channel data to the client. */
663 if (packet_not_very_much_data_to_write())
664 channel_output_poll();
665
666 /*
667 * Bail out of the loop if the program has closed its output
668 * descriptors, and we have no more data to send to the
669 * client, and there is no pending buffered data.
670 */
671 if (fdout_eof && fderr_eof && !packet_have_data_to_write() &&
672 buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) {
673 if (!channel_still_open())
674 break;
675 if (!waiting_termination) {
676 const char *s = "Waiting for forwarded connections to terminate...\r\n";
677 char *cp;
678 waiting_termination = 1;
679 buffer_append(&stderr_buffer, s, strlen(s));
680
681 /* Display list of open channels. */
682 cp = channel_open_message();
683 buffer_append(&stderr_buffer, cp, strlen(cp));
684 xfree(cp);
685 }
686 }
687 max_fd = MAX(connection_in, connection_out);
688 max_fd = MAX(max_fd, fdin);
689 max_fd = MAX(max_fd, fdout);
690 max_fd = MAX(max_fd, fderr);
473db5ab 691 max_fd = MAX(max_fd, notify_pipe[0]);
3c0ef626 692
693 /* Sleep in select() until we can do something. */
694 wait_until_can_do_something(&readset, &writeset, &max_fd,
695 &nalloc, max_time_milliseconds);
696
08822d99 697 if (received_sigterm) {
698 logit("Exiting on signal %d", received_sigterm);
699 /* Clean up sessions, utmp, etc. */
700 cleanup_exit(255);
701 }
702
3c0ef626 703 /* Process any channel events. */
704 channel_after_select(readset, writeset);
705
706 /* Process input from the client and from program stdout/stderr. */
707 process_input(readset);
708
709 /* Process output to the client and to program stdin. */
710 process_output(writeset);
711 }
712 if (readset)
713 xfree(readset);
714 if (writeset)
715 xfree(writeset);
716
717 /* Cleanup and termination code. */
718
719 /* Wait until all output has been sent to the client. */
720 drain_output();
721
722 debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.",
473db5ab 723 stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes);
3c0ef626 724
725 /* Free and clear the buffers. */
726 buffer_free(&stdin_buffer);
727 buffer_free(&stdout_buffer);
728 buffer_free(&stderr_buffer);
729
730 /* Close the file descriptors. */
731 if (fdout != -1)
732 close(fdout);
733 fdout = -1;
734 fdout_eof = 1;
735 if (fderr != -1)
736 close(fderr);
737 fderr = -1;
738 fderr_eof = 1;
739 if (fdin != -1)
740 close(fdin);
741 fdin = -1;
742
743 channel_free_all();
744
745 /* We no longer want our SIGCHLD handler to be called. */
746 mysignal(SIGCHLD, SIG_DFL);
747
473db5ab 748 while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0)
749 if (errno != EINTR)
750 packet_disconnect("wait: %.100s", strerror(errno));
751 if (wait_pid != pid)
752 error("Strange, wait returned pid %ld, expected %ld",
753 (long)wait_pid, (long)pid);
3c0ef626 754
755 /* Check if it exited normally. */
756 if (WIFEXITED(wait_status)) {
757 /* Yes, normal exit. Get exit status and send it to the client. */
758 debug("Command exited with status %d.", WEXITSTATUS(wait_status));
759 packet_start(SSH_SMSG_EXITSTATUS);
760 packet_put_int(WEXITSTATUS(wait_status));
761 packet_send();
762 packet_write_wait();
763
764 /*
765 * Wait for exit confirmation. Note that there might be
766 * other packets coming before it; however, the program has
767 * already died so we just ignore them. The client is
768 * supposed to respond with the confirmation when it receives
769 * the exit status.
770 */
771 do {
473db5ab 772 type = packet_read();
3c0ef626 773 }
774 while (type != SSH_CMSG_EXIT_CONFIRMATION);
775
776 debug("Received exit confirmation.");
777 return;
778 }
779 /* Check if the program terminated due to a signal. */
780 if (WIFSIGNALED(wait_status))
781 packet_disconnect("Command terminated on signal %d.",
782 WTERMSIG(wait_status));
783
784 /* Some weird exit cause. Just exit. */
785 packet_disconnect("wait returned status %04x.", wait_status);
786 /* NOTREACHED */
787}
788
789static void
790collect_children(void)
791{
792 pid_t pid;
793 sigset_t oset, nset;
794 int status;
795
796 /* block SIGCHLD while we check for dead children */
797 sigemptyset(&nset);
798 sigaddset(&nset, SIGCHLD);
799 sigprocmask(SIG_BLOCK, &nset, &oset);
800 if (child_terminated) {
30460aeb 801 debug("Received SIGCHLD.");
473db5ab 802 while ((pid = waitpid(-1, &status, WNOHANG)) > 0 ||
803 (pid < 0 && errno == EINTR))
804 if (pid > 0)
805 session_close_by_pid(pid, status);
3c0ef626 806 child_terminated = 0;
807 }
808 sigprocmask(SIG_SETMASK, &oset, NULL);
809}
810
811void
812server_loop2(Authctxt *authctxt)
813{
814 fd_set *readset = NULL, *writeset = NULL;
815 int rekeying = 0, max_fd, nalloc = 0;
816
817 debug("Entering interactive session for SSH2.");
818
819 mysignal(SIGCHLD, sigchld_handler);
820 child_terminated = 0;
821 connection_in = packet_get_connection_in();
822 connection_out = packet_get_connection_out();
823
08822d99 824 if (!use_privsep) {
825 signal(SIGTERM, sigterm_handler);
826 signal(SIGINT, sigterm_handler);
827 signal(SIGQUIT, sigterm_handler);
828 }
829
473db5ab 830 notify_setup();
831
3c0ef626 832 max_fd = MAX(connection_in, connection_out);
473db5ab 833 max_fd = MAX(max_fd, notify_pipe[0]);
3c0ef626 834
835 server_init_dispatch();
836
837 for (;;) {
838 process_buffered_input_packets();
839
840 rekeying = (xxx_kex != NULL && !xxx_kex->done);
841
842 if (!rekeying && packet_not_very_much_data_to_write())
843 channel_output_poll();
844 wait_until_can_do_something(&readset, &writeset, &max_fd,
845 &nalloc, 0);
846
08822d99 847 if (received_sigterm) {
848 logit("Exiting on signal %d", received_sigterm);
849 /* Clean up sessions, utmp, etc. */
850 cleanup_exit(255);
851 }
852
3c0ef626 853 collect_children();
473db5ab 854 if (!rekeying) {
3c0ef626 855 channel_after_select(readset, writeset);
473db5ab 856 if (packet_need_rekeying()) {
857 debug("need rekeying");
858 xxx_kex->done = 0;
859 kex_send_kexinit(xxx_kex);
860 }
861 }
3c0ef626 862 process_input(readset);
863 if (connection_closed)
864 break;
865 process_output(writeset);
866 }
867 collect_children();
868
869 if (readset)
870 xfree(readset);
871 if (writeset)
872 xfree(writeset);
873
874 /* free all channels, no more reads and writes */
875 channel_free_all();
876
877 /* free remaining sessions, e.g. remove wtmp entries */
473db5ab 878 session_destroy_all(NULL);
3c0ef626 879}
880
881static void
473db5ab 882server_input_keep_alive(int type, u_int32_t seq, void *ctxt)
3c0ef626 883{
473db5ab 884 debug("Got %d/%u for keepalive", type, seq);
885 /*
3c0ef626 886 * reset timeout, since we got a sane answer from the client.
887 * even if this was generated by something other than
888 * the bogus CHANNEL_REQUEST we send for keepalives.
889 */
473db5ab 890 client_alive_timeouts = 0;
3c0ef626 891}
892
3c0ef626 893static void
473db5ab 894server_input_stdin_data(int type, u_int32_t seq, void *ctxt)
3c0ef626 895{
896 char *data;
897 u_int data_len;
898
899 /* Stdin data from the client. Append it to the buffer. */
900 /* Ignore any data if the client has closed stdin. */
901 if (fdin == -1)
902 return;
903 data = packet_get_string(&data_len);
473db5ab 904 packet_check_eom();
3c0ef626 905 buffer_append(&stdin_buffer, data, data_len);
906 memset(data, 0, data_len);
907 xfree(data);
908}
909
910static void
473db5ab 911server_input_eof(int type, u_int32_t seq, void *ctxt)
3c0ef626 912{
913 /*
914 * Eof from the client. The stdin descriptor to the
915 * program will be closed when all buffered data has
916 * drained.
917 */
918 debug("EOF received for stdin.");
473db5ab 919 packet_check_eom();
3c0ef626 920 stdin_eof = 1;
921}
922
923static void
473db5ab 924server_input_window_size(int type, u_int32_t seq, void *ctxt)
3c0ef626 925{
30460aeb 926 u_int row = packet_get_int();
927 u_int col = packet_get_int();
928 u_int xpixel = packet_get_int();
929 u_int ypixel = packet_get_int();
3c0ef626 930
931 debug("Window change received.");
473db5ab 932 packet_check_eom();
3c0ef626 933 if (fdin != -1)
934 pty_change_window_size(fdin, row, col, xpixel, ypixel);
935}
936
937static Channel *
473db5ab 938server_request_direct_tcpip(void)
3c0ef626 939{
940 Channel *c;
941 int sock;
942 char *target, *originator;
943 int target_port, originator_port;
944
945 target = packet_get_string(NULL);
946 target_port = packet_get_int();
947 originator = packet_get_string(NULL);
948 originator_port = packet_get_int();
473db5ab 949 packet_check_eom();
3c0ef626 950
951 debug("server_request_direct_tcpip: originator %s port %d, target %s port %d",
473db5ab 952 originator, originator_port, target, target_port);
3c0ef626 953
954 /* XXX check permission */
955 sock = channel_connect_to(target, target_port);
956 xfree(target);
957 xfree(originator);
958 if (sock < 0)
959 return NULL;
a7213e65 960 if (options.hpn_disabled)
6df46d40 961 c = channel_new("direct-tcpip", SSH_CHANNEL_CONNECTING,
962 sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT,
963 CHAN_TCP_PACKET_DEFAULT, 0, "direct-tcpip", 1);
a7213e65 964 else
965 c = channel_new("direct-tcpip", SSH_CHANNEL_CONNECTING,
966 sock, sock, -1, options.hpn_buffer_size,
967 CHAN_TCP_PACKET_DEFAULT, 0, "direct-tcpip", 1);
3c0ef626 968 return c;
969}
970
08822d99 971static Channel *
972server_request_tun(void)
973{
974 Channel *c = NULL;
975 int mode, tun;
976 int sock;
977
978 mode = packet_get_int();
979 switch (mode) {
980 case SSH_TUNMODE_POINTOPOINT:
981 case SSH_TUNMODE_ETHERNET:
982 break;
983 default:
984 packet_send_debug("Unsupported tunnel device mode.");
985 return NULL;
986 }
987 if ((options.permit_tun & mode) == 0) {
988 packet_send_debug("Server has rejected tunnel device "
989 "forwarding");
990 return NULL;
991 }
992
993 tun = packet_get_int();
994 if (forced_tun_device != -1) {
30460aeb 995 if (tun != SSH_TUNID_ANY && forced_tun_device != tun)
08822d99 996 goto done;
997 tun = forced_tun_device;
998 }
999 sock = tun_open(tun, mode);
1000 if (sock < 0)
1001 goto done;
a7213e65 1002 if (options.hpn_disabled)
6df46d40 1003 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1,
1004 CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
a7213e65 1005 else
1006 c = channel_new("tun", SSH_CHANNEL_OPEN, sock, sock, -1,
1007 options.hpn_buffer_size, CHAN_TCP_PACKET_DEFAULT, 0, "tun", 1);
08822d99 1008 c->datagram = 1;
1009#if defined(SSH_TUN_FILTER)
1010 if (mode == SSH_TUNMODE_POINTOPOINT)
1011 channel_register_filter(c->self, sys_tun_infilter,
1012 sys_tun_outfilter);
1013#endif
1014
1015 done:
1016 if (c == NULL)
1017 packet_send_debug("Failed to open the tunnel device.");
1018 return c;
1019}
1020
3c0ef626 1021static Channel *
473db5ab 1022server_request_session(void)
3c0ef626 1023{
1024 Channel *c;
1025
1026 debug("input_session_request");
473db5ab 1027 packet_check_eom();
3c0ef626 1028 /*
1029 * A server session has no fd to read or write until a
1030 * CHANNEL_REQUEST for a shell is made, so we set the type to
1031 * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all
1032 * CHANNEL_REQUEST messages is registered.
1033 */
473db5ab 1034 c = channel_new("session", SSH_CHANNEL_LARVAL,
3c0ef626 1035 -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT,
473db5ab 1036 0, "server-session", 1);
a7213e65 1037 if ((options.tcp_rcv_buf_poll > 0) && (!options.hpn_disabled))
473db5ab 1038 c->dynamic_window = 1;
1039 if (session_open(the_authctxt, c->self) != 1) {
3c0ef626 1040 debug("session open failed, free channel %d", c->self);
1041 channel_free(c);
1042 return NULL;
1043 }
08822d99 1044 channel_register_cleanup(c->self, session_close_by_channel, 0);
3c0ef626 1045 return c;
1046}
1047
1048static void
473db5ab 1049server_input_channel_open(int type, u_int32_t seq, void *ctxt)
3c0ef626 1050{
1051 Channel *c = NULL;
1052 char *ctype;
3c0ef626 1053 int rchan;
473db5ab 1054 u_int rmaxpack, rwindow, len;
3c0ef626 1055
1056 ctype = packet_get_string(&len);
1057 rchan = packet_get_int();
1058 rwindow = packet_get_int();
1059 rmaxpack = packet_get_int();
1060
1061 debug("server_input_channel_open: ctype %s rchan %d win %d max %d",
1062 ctype, rchan, rwindow, rmaxpack);
1063
1064 if (strcmp(ctype, "session") == 0) {
473db5ab 1065 c = server_request_session();
3c0ef626 1066 } else if (strcmp(ctype, "direct-tcpip") == 0) {
473db5ab 1067 c = server_request_direct_tcpip();
08822d99 1068 } else if (strcmp(ctype, "tun@openssh.com") == 0) {
1069 c = server_request_tun();
3c0ef626 1070 }
1071 if (c != NULL) {
1072 debug("server_input_channel_open: confirm %s", ctype);
1073 c->remote_id = rchan;
1074 c->remote_window = rwindow;
1075 c->remote_maxpacket = rmaxpack;
1076 if (c->type != SSH_CHANNEL_CONNECTING) {
1077 packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION);
1078 packet_put_int(c->remote_id);
1079 packet_put_int(c->self);
1080 packet_put_int(c->local_window);
1081 packet_put_int(c->local_maxpacket);
1082 packet_send();
1083 }
1084 } else {
1085 debug("server_input_channel_open: failure %s", ctype);
1086 packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE);
1087 packet_put_int(rchan);
1088 packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED);
1089 if (!(datafellows & SSH_BUG_OPENFAILURE)) {
1090 packet_put_cstring("open failed");
1091 packet_put_cstring("");
1092 }
1093 packet_send();
1094 }
1095 xfree(ctype);
1096}
1097
1098static void
473db5ab 1099server_input_global_request(int type, u_int32_t seq, void *ctxt)
3c0ef626 1100{
1101 char *rtype;
1102 int want_reply;
1103 int success = 0;
1104
1105 rtype = packet_get_string(NULL);
1106 want_reply = packet_get_char();
1107 debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply);
1108
1109 /* -R style forwarding */
1110 if (strcmp(rtype, "tcpip-forward") == 0) {
1111 struct passwd *pw;
1112 char *listen_address;
1113 u_short listen_port;
1114
473db5ab 1115 pw = the_authctxt->pw;
1116 if (pw == NULL || !the_authctxt->valid)
1117 fatal("server_input_global_request: no/invalid user");
1118 listen_address = packet_get_string(NULL);
3c0ef626 1119 listen_port = (u_short)packet_get_int();
1120 debug("server_input_global_request: tcpip-forward listen %s port %d",
1121 listen_address, listen_port);
1122
1123 /* check permissions */
1124 if (!options.allow_tcp_forwarding ||
473db5ab 1125 no_port_forwarding_flag
1126#ifndef NO_IPPORT_RESERVED_CONCEPT
1127 || (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)
1128#endif
1129 ) {
3c0ef626 1130 success = 0;
1131 packet_send_debug("Server has disabled port forwarding.");
1132 } else {
1133 /* Start listening on the port */
473db5ab 1134 success = channel_setup_remote_fwd_listener(
a7213e65 1135 listen_address, listen_port, options.gateway_ports,
1136 options.hpn_disabled, options.hpn_buffer_size);
3c0ef626 1137 }
1138 xfree(listen_address);
473db5ab 1139 } else if (strcmp(rtype, "cancel-tcpip-forward") == 0) {
1140 char *cancel_address;
1141 u_short cancel_port;
1142
1143 cancel_address = packet_get_string(NULL);
1144 cancel_port = (u_short)packet_get_int();
1145 debug("%s: cancel-tcpip-forward addr %s port %d", __func__,
1146 cancel_address, cancel_port);
1147
1148 success = channel_cancel_rport_listener(cancel_address,
1149 cancel_port);
30460aeb 1150 xfree(cancel_address);
3c0ef626 1151 }
1152 if (want_reply) {
1153 packet_start(success ?
1154 SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE);
1155 packet_send();
1156 packet_write_wait();
1157 }
1158 xfree(rtype);
1159}
30460aeb 1160
473db5ab 1161static void
1162server_input_channel_req(int type, u_int32_t seq, void *ctxt)
1163{
1164 Channel *c;
1165 int id, reply, success = 0;
1166 char *rtype;
1167
1168 id = packet_get_int();
1169 rtype = packet_get_string(NULL);
1170 reply = packet_get_char();
1171
1172 debug("server_input_channel_req: channel %d request %s reply %d",
1173 id, rtype, reply);
1174
1175 if ((c = channel_lookup(id)) == NULL)
1176 packet_disconnect("server_input_channel_req: "
1177 "unknown channel %d", id);
1178 if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN)
1179 success = session_input_channel_req(c, rtype);
1180 if (reply) {
1181 packet_start(success ?
1182 SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE);
1183 packet_put_int(c->remote_id);
1184 packet_send();
1185 }
1186 xfree(rtype);
1187}
3c0ef626 1188
1189static void
1190server_init_dispatch_20(void)
1191{
1192 debug("server_init_dispatch_20");
1193 dispatch_init(&dispatch_protocol_error);
1194 dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose);
1195 dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data);
1196 dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof);
1197 dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data);
1198 dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open);
1199 dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1200 dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
473db5ab 1201 dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req);
3c0ef626 1202 dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust);
1203 dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request);
1204 /* client_alive */
473db5ab 1205 dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_keep_alive);
1206 dispatch_set(SSH2_MSG_REQUEST_SUCCESS, &server_input_keep_alive);
1207 dispatch_set(SSH2_MSG_REQUEST_FAILURE, &server_input_keep_alive);
3c0ef626 1208 /* rekeying */
1209 dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit);
1210}
1211static void
1212server_init_dispatch_13(void)
1213{
1214 debug("server_init_dispatch_13");
1215 dispatch_init(NULL);
1216 dispatch_set(SSH_CMSG_EOF, &server_input_eof);
1217 dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data);
1218 dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size);
1219 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close);
1220 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation);
1221 dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data);
1222 dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation);
1223 dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure);
1224 dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open);
1225}
1226static void
1227server_init_dispatch_15(void)
1228{
1229 server_init_dispatch_13();
1230 debug("server_init_dispatch_15");
1231 dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof);
1232 dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose);
1233}
1234static void
1235server_init_dispatch(void)
1236{
1237 if (compat20)
1238 server_init_dispatch_20();
1239 else if (compat13)
1240 server_init_dispatch_13();
1241 else
1242 server_init_dispatch_15();
1243}
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