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1 | /* | |
2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * Server main loop for handling the interactive session. | |
6 | * | |
7 | * As far as I am concerned, the code I have written for this software | |
8 | * can be used freely for any purpose. Any derived versions of this | |
9 | * software must be clearly marked as such, and if the derived work is | |
10 | * incompatible with the protocol description in the RFC file, it must be | |
11 | * called by a name other than "ssh" or "Secure Shell". | |
12 | * | |
13 | * SSH2 support by Markus Friedl. | |
14 | * Copyright (c) 2000 Markus Friedl. All rights reserved. | |
15 | * | |
16 | * Redistribution and use in source and binary forms, with or without | |
17 | * modification, are permitted provided that the following conditions | |
18 | * are met: | |
19 | * 1. Redistributions of source code must retain the above copyright | |
20 | * notice, this list of conditions and the following disclaimer. | |
21 | * 2. Redistributions in binary form must reproduce the above copyright | |
22 | * notice, this list of conditions and the following disclaimer in the | |
23 | * documentation and/or other materials provided with the distribution. | |
24 | * | |
25 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
26 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
27 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
28 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
29 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
30 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
31 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
32 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
33 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
34 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
35 | */ | |
36 | ||
37 | #include "includes.h" | |
38 | RCSID("$OpenBSD: serverloop.c,v 1.63 2001/04/29 19:16:52 markus Exp $"); | |
39 | ||
40 | #include "xmalloc.h" | |
41 | #include "packet.h" | |
42 | #include "buffer.h" | |
43 | #include "log.h" | |
44 | #include "servconf.h" | |
45 | #include "sshpty.h" | |
46 | #include "channels.h" | |
47 | #include "compat.h" | |
48 | #include "ssh1.h" | |
49 | #include "ssh2.h" | |
50 | #include "auth.h" | |
51 | #include "session.h" | |
52 | #include "dispatch.h" | |
53 | #include "auth-options.h" | |
54 | #include "serverloop.h" | |
55 | #include "misc.h" | |
56 | #include "kex.h" | |
57 | ||
58 | extern ServerOptions options; | |
59 | ||
60 | /* XXX */ | |
61 | extern Kex *xxx_kex; | |
62 | ||
63 | static Buffer stdin_buffer; /* Buffer for stdin data. */ | |
64 | static Buffer stdout_buffer; /* Buffer for stdout data. */ | |
65 | static Buffer stderr_buffer; /* Buffer for stderr data. */ | |
66 | static int fdin; /* Descriptor for stdin (for writing) */ | |
67 | static int fdout; /* Descriptor for stdout (for reading); | |
68 | May be same number as fdin. */ | |
69 | static int fderr; /* Descriptor for stderr. May be -1. */ | |
70 | static long stdin_bytes = 0; /* Number of bytes written to stdin. */ | |
71 | static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ | |
72 | static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ | |
73 | static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ | |
74 | static int stdin_eof = 0; /* EOF message received from client. */ | |
75 | static int fdout_eof = 0; /* EOF encountered reading from fdout. */ | |
76 | static int fderr_eof = 0; /* EOF encountered readung from fderr. */ | |
77 | static int fdin_is_tty = 0; /* fdin points to a tty. */ | |
78 | static int connection_in; /* Connection to client (input). */ | |
79 | static int connection_out; /* Connection to client (output). */ | |
80 | static int connection_closed = 0; /* Connection to client closed. */ | |
81 | static u_int buffer_high; /* "Soft" max buffer size. */ | |
82 | ||
83 | /* | |
84 | * This SIGCHLD kludge is used to detect when the child exits. The server | |
85 | * will exit after that, as soon as forwarded connections have terminated. | |
86 | */ | |
87 | ||
88 | static pid_t child_pid; /* Pid of the child. */ | |
89 | static volatile int child_terminated; /* The child has terminated. */ | |
90 | static volatile int child_wait_status; /* Status from wait(). */ | |
91 | ||
92 | void server_init_dispatch(void); | |
93 | ||
94 | int client_alive_timeouts = 0; | |
95 | ||
96 | void | |
97 | sigchld_handler(int sig) | |
98 | { | |
99 | int save_errno = errno; | |
100 | pid_t wait_pid; | |
101 | ||
102 | debug("Received SIGCHLD."); | |
103 | wait_pid = wait((int *) &child_wait_status); | |
104 | if (wait_pid != -1) { | |
105 | if (wait_pid != child_pid) | |
106 | error("Strange, got SIGCHLD and wait returned pid %d but child is %d", | |
107 | wait_pid, child_pid); | |
108 | if (WIFEXITED(child_wait_status) || | |
109 | WIFSIGNALED(child_wait_status)) | |
110 | child_terminated = 1; | |
111 | } | |
112 | signal(SIGCHLD, sigchld_handler); | |
113 | errno = save_errno; | |
114 | } | |
115 | void | |
116 | sigchld_handler2(int sig) | |
117 | { | |
118 | int save_errno = errno; | |
119 | debug("Received SIGCHLD."); | |
120 | child_terminated = 1; | |
121 | mysignal(SIGCHLD, sigchld_handler2); | |
122 | errno = save_errno; | |
123 | } | |
124 | ||
125 | /* | |
126 | * Make packets from buffered stderr data, and buffer it for sending | |
127 | * to the client. | |
128 | */ | |
129 | void | |
130 | make_packets_from_stderr_data(void) | |
131 | { | |
132 | int len; | |
133 | ||
134 | /* Send buffered stderr data to the client. */ | |
135 | while (buffer_len(&stderr_buffer) > 0 && | |
136 | packet_not_very_much_data_to_write()) { | |
137 | len = buffer_len(&stderr_buffer); | |
138 | if (packet_is_interactive()) { | |
139 | if (len > 512) | |
140 | len = 512; | |
141 | } else { | |
142 | /* Keep the packets at reasonable size. */ | |
143 | if (len > packet_get_maxsize()) | |
144 | len = packet_get_maxsize(); | |
145 | } | |
146 | packet_start(SSH_SMSG_STDERR_DATA); | |
147 | packet_put_string(buffer_ptr(&stderr_buffer), len); | |
148 | packet_send(); | |
149 | buffer_consume(&stderr_buffer, len); | |
150 | stderr_bytes += len; | |
151 | } | |
152 | } | |
153 | ||
154 | /* | |
155 | * Make packets from buffered stdout data, and buffer it for sending to the | |
156 | * client. | |
157 | */ | |
158 | void | |
159 | make_packets_from_stdout_data(void) | |
160 | { | |
161 | int len; | |
162 | ||
163 | /* Send buffered stdout data to the client. */ | |
164 | while (buffer_len(&stdout_buffer) > 0 && | |
165 | packet_not_very_much_data_to_write()) { | |
166 | len = buffer_len(&stdout_buffer); | |
167 | if (packet_is_interactive()) { | |
168 | if (len > 512) | |
169 | len = 512; | |
170 | } else { | |
171 | /* Keep the packets at reasonable size. */ | |
172 | if (len > packet_get_maxsize()) | |
173 | len = packet_get_maxsize(); | |
174 | } | |
175 | packet_start(SSH_SMSG_STDOUT_DATA); | |
176 | packet_put_string(buffer_ptr(&stdout_buffer), len); | |
177 | packet_send(); | |
178 | buffer_consume(&stdout_buffer, len); | |
179 | stdout_bytes += len; | |
180 | } | |
181 | } | |
182 | ||
183 | /* | |
184 | * Sleep in select() until we can do something. This will initialize the | |
185 | * select masks. Upon return, the masks will indicate which descriptors | |
186 | * have data or can accept data. Optionally, a maximum time can be specified | |
187 | * for the duration of the wait (0 = infinite). | |
188 | */ | |
189 | void | |
190 | wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, | |
191 | u_int max_time_milliseconds) | |
192 | { | |
193 | struct timeval tv, *tvp; | |
194 | int ret; | |
195 | int client_alive_scheduled = 0; | |
196 | ||
197 | /* | |
198 | * if using client_alive, set the max timeout accordingly, | |
199 | * and indicate that this particular timeout was for client | |
200 | * alive by setting the client_alive_scheduled flag. | |
201 | * | |
202 | * this could be randomized somewhat to make traffic | |
203 | * analysis more difficult, but we're not doing it yet. | |
204 | */ | |
205 | if (max_time_milliseconds == 0 && options.client_alive_interval) { | |
206 | client_alive_scheduled = 1; | |
207 | max_time_milliseconds = options.client_alive_interval * 1000; | |
208 | } else | |
209 | client_alive_scheduled = 0; | |
210 | ||
211 | /* When select fails we restart from here. */ | |
212 | retry_select: | |
213 | ||
214 | /* Allocate and update select() masks for channel descriptors. */ | |
215 | channel_prepare_select(readsetp, writesetp, maxfdp, 0); | |
216 | ||
217 | if (compat20) { | |
218 | /* wrong: bad condition XXX */ | |
219 | if (channel_not_very_much_buffered_data()) | |
220 | FD_SET(connection_in, *readsetp); | |
221 | } else { | |
222 | /* | |
223 | * Read packets from the client unless we have too much | |
224 | * buffered stdin or channel data. | |
225 | */ | |
226 | if (buffer_len(&stdin_buffer) < buffer_high && | |
227 | channel_not_very_much_buffered_data()) | |
228 | FD_SET(connection_in, *readsetp); | |
229 | /* | |
230 | * If there is not too much data already buffered going to | |
231 | * the client, try to get some more data from the program. | |
232 | */ | |
233 | if (packet_not_very_much_data_to_write()) { | |
234 | if (!fdout_eof) | |
235 | FD_SET(fdout, *readsetp); | |
236 | if (!fderr_eof) | |
237 | FD_SET(fderr, *readsetp); | |
238 | } | |
239 | /* | |
240 | * If we have buffered data, try to write some of that data | |
241 | * to the program. | |
242 | */ | |
243 | if (fdin != -1 && buffer_len(&stdin_buffer) > 0) | |
244 | FD_SET(fdin, *writesetp); | |
245 | } | |
246 | ||
247 | /* | |
248 | * If we have buffered packet data going to the client, mark that | |
249 | * descriptor. | |
250 | */ | |
251 | if (packet_have_data_to_write()) | |
252 | FD_SET(connection_out, *writesetp); | |
253 | ||
254 | /* | |
255 | * If child has terminated and there is enough buffer space to read | |
256 | * from it, then read as much as is available and exit. | |
257 | */ | |
258 | if (child_terminated && packet_not_very_much_data_to_write()) | |
259 | if (max_time_milliseconds == 0 || client_alive_scheduled) | |
260 | max_time_milliseconds = 100; | |
261 | ||
262 | if (max_time_milliseconds == 0) | |
263 | tvp = NULL; | |
264 | else { | |
265 | tv.tv_sec = max_time_milliseconds / 1000; | |
266 | tv.tv_usec = 1000 * (max_time_milliseconds % 1000); | |
267 | tvp = &tv; | |
268 | } | |
269 | if (tvp!=NULL) | |
270 | debug3("tvp!=NULL kid %d mili %d", child_terminated, max_time_milliseconds); | |
271 | ||
272 | /* Wait for something to happen, or the timeout to expire. */ | |
273 | ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); | |
274 | ||
275 | if (ret == -1) { | |
276 | if (errno != EINTR) | |
277 | error("select: %.100s", strerror(errno)); | |
278 | else | |
279 | goto retry_select; | |
280 | } | |
281 | if (ret == 0 && client_alive_scheduled) { | |
282 | /* timeout, check to see how many we have had */ | |
283 | client_alive_timeouts++; | |
284 | ||
285 | if (client_alive_timeouts > options.client_alive_count_max ) { | |
286 | packet_disconnect( | |
287 | "Timeout, your session not responding."); | |
288 | } else { | |
289 | /* | |
290 | * send a bogus channel request with "wantreply" | |
291 | * we should get back a failure | |
292 | */ | |
293 | int id; | |
294 | ||
295 | id = channel_find_open(); | |
296 | if (id != -1) { | |
297 | channel_request_start(id, | |
298 | "keepalive@openssh.com", 1); | |
299 | packet_send(); | |
300 | } else | |
301 | packet_disconnect( | |
302 | "No open channels after timeout!"); | |
303 | } | |
304 | } | |
305 | } | |
306 | ||
307 | /* | |
308 | * Processes input from the client and the program. Input data is stored | |
309 | * in buffers and processed later. | |
310 | */ | |
311 | void | |
312 | process_input(fd_set * readset) | |
313 | { | |
314 | int len; | |
315 | char buf[16384]; | |
316 | ||
317 | /* Read and buffer any input data from the client. */ | |
318 | if (FD_ISSET(connection_in, readset)) { | |
319 | len = read(connection_in, buf, sizeof(buf)); | |
320 | if (len == 0) { | |
321 | verbose("Connection closed by remote host."); | |
322 | connection_closed = 1; | |
323 | if (compat20) | |
324 | return; | |
325 | fatal_cleanup(); | |
326 | } else if (len < 0) { | |
327 | if (errno != EINTR && errno != EAGAIN) { | |
328 | verbose("Read error from remote host: %.100s", strerror(errno)); | |
329 | fatal_cleanup(); | |
330 | } | |
331 | } else { | |
332 | /* Buffer any received data. */ | |
333 | packet_process_incoming(buf, len); | |
334 | } | |
335 | } | |
336 | if (compat20) | |
337 | return; | |
338 | ||
339 | /* Read and buffer any available stdout data from the program. */ | |
340 | if (!fdout_eof && FD_ISSET(fdout, readset)) { | |
341 | len = read(fdout, buf, sizeof(buf)); | |
342 | if (len < 0 && (errno == EINTR || errno == EAGAIN)) { | |
343 | /* do nothing */ | |
344 | } else if (len <= 0) { | |
345 | fdout_eof = 1; | |
346 | } else { | |
347 | buffer_append(&stdout_buffer, buf, len); | |
348 | fdout_bytes += len; | |
349 | } | |
350 | } | |
351 | /* Read and buffer any available stderr data from the program. */ | |
352 | if (!fderr_eof && FD_ISSET(fderr, readset)) { | |
353 | len = read(fderr, buf, sizeof(buf)); | |
354 | if (len < 0 && (errno == EINTR || errno == EAGAIN)) { | |
355 | /* do nothing */ | |
356 | } else if (len <= 0) { | |
357 | fderr_eof = 1; | |
358 | } else { | |
359 | buffer_append(&stderr_buffer, buf, len); | |
360 | } | |
361 | } | |
362 | } | |
363 | ||
364 | /* | |
365 | * Sends data from internal buffers to client program stdin. | |
366 | */ | |
367 | void | |
368 | process_output(fd_set * writeset) | |
369 | { | |
370 | struct termios tio; | |
371 | int len; | |
372 | ||
373 | /* Write buffered data to program stdin. */ | |
374 | if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { | |
375 | len = write(fdin, buffer_ptr(&stdin_buffer), | |
376 | buffer_len(&stdin_buffer)); | |
377 | if (len < 0 && (errno == EINTR || errno == EAGAIN)) { | |
378 | /* do nothing */ | |
379 | } else if (len <= 0) { | |
380 | #ifdef USE_PIPES | |
381 | close(fdin); | |
382 | #else | |
383 | if (fdin != fdout) | |
384 | close(fdin); | |
385 | else | |
386 | shutdown(fdin, SHUT_WR); /* We will no longer send. */ | |
387 | #endif | |
388 | fdin = -1; | |
389 | } else { | |
390 | /* Successful write. */ | |
391 | if (fdin_is_tty && tcgetattr(fdin, &tio) == 0 && | |
392 | !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { | |
393 | /* | |
394 | * Simulate echo to reduce the impact of | |
395 | * traffic analysis | |
396 | */ | |
397 | packet_send_ignore(len); | |
398 | packet_send(); | |
399 | } | |
400 | /* Consume the data from the buffer. */ | |
401 | buffer_consume(&stdin_buffer, len); | |
402 | /* Update the count of bytes written to the program. */ | |
403 | stdin_bytes += len; | |
404 | } | |
405 | } | |
406 | /* Send any buffered packet data to the client. */ | |
407 | if (FD_ISSET(connection_out, writeset)) | |
408 | packet_write_poll(); | |
409 | } | |
410 | ||
411 | /* | |
412 | * Wait until all buffered output has been sent to the client. | |
413 | * This is used when the program terminates. | |
414 | */ | |
415 | void | |
416 | drain_output(void) | |
417 | { | |
418 | /* Send any buffered stdout data to the client. */ | |
419 | if (buffer_len(&stdout_buffer) > 0) { | |
420 | packet_start(SSH_SMSG_STDOUT_DATA); | |
421 | packet_put_string(buffer_ptr(&stdout_buffer), | |
422 | buffer_len(&stdout_buffer)); | |
423 | packet_send(); | |
424 | /* Update the count of sent bytes. */ | |
425 | stdout_bytes += buffer_len(&stdout_buffer); | |
426 | } | |
427 | /* Send any buffered stderr data to the client. */ | |
428 | if (buffer_len(&stderr_buffer) > 0) { | |
429 | packet_start(SSH_SMSG_STDERR_DATA); | |
430 | packet_put_string(buffer_ptr(&stderr_buffer), | |
431 | buffer_len(&stderr_buffer)); | |
432 | packet_send(); | |
433 | /* Update the count of sent bytes. */ | |
434 | stderr_bytes += buffer_len(&stderr_buffer); | |
435 | } | |
436 | /* Wait until all buffered data has been written to the client. */ | |
437 | packet_write_wait(); | |
438 | } | |
439 | ||
440 | void | |
441 | process_buffered_input_packets(void) | |
442 | { | |
443 | dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); | |
444 | } | |
445 | ||
446 | /* | |
447 | * Performs the interactive session. This handles data transmission between | |
448 | * the client and the program. Note that the notion of stdin, stdout, and | |
449 | * stderr in this function is sort of reversed: this function writes to | |
450 | * stdin (of the child program), and reads from stdout and stderr (of the | |
451 | * child program). | |
452 | */ | |
453 | void | |
454 | server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) | |
455 | { | |
456 | fd_set *readset = NULL, *writeset = NULL; | |
457 | int max_fd; | |
458 | int wait_status; /* Status returned by wait(). */ | |
459 | pid_t wait_pid; /* pid returned by wait(). */ | |
460 | int waiting_termination = 0; /* Have displayed waiting close message. */ | |
461 | u_int max_time_milliseconds; | |
462 | u_int previous_stdout_buffer_bytes; | |
463 | u_int stdout_buffer_bytes; | |
464 | int type; | |
465 | ||
466 | debug("Entering interactive session."); | |
467 | ||
468 | /* Initialize the SIGCHLD kludge. */ | |
469 | child_pid = pid; | |
470 | child_terminated = 0; | |
471 | signal(SIGCHLD, sigchld_handler); | |
472 | ||
473 | /* Initialize our global variables. */ | |
474 | fdin = fdin_arg; | |
475 | fdout = fdout_arg; | |
476 | fderr = fderr_arg; | |
477 | ||
478 | /* nonblocking IO */ | |
479 | set_nonblock(fdin); | |
480 | set_nonblock(fdout); | |
481 | /* we don't have stderr for interactive terminal sessions, see below */ | |
482 | if (fderr != -1) | |
483 | set_nonblock(fderr); | |
484 | ||
485 | if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) | |
486 | fdin_is_tty = 1; | |
487 | ||
488 | connection_in = packet_get_connection_in(); | |
489 | connection_out = packet_get_connection_out(); | |
490 | ||
491 | previous_stdout_buffer_bytes = 0; | |
492 | ||
493 | /* Set approximate I/O buffer size. */ | |
494 | if (packet_is_interactive()) | |
495 | buffer_high = 4096; | |
496 | else | |
497 | buffer_high = 64 * 1024; | |
498 | ||
499 | /* Initialize max_fd to the maximum of the known file descriptors. */ | |
500 | max_fd = MAX(fdin, fdout); | |
501 | if (fderr != -1) | |
502 | max_fd = MAX(max_fd, fderr); | |
503 | max_fd = MAX(max_fd, connection_in); | |
504 | max_fd = MAX(max_fd, connection_out); | |
505 | ||
506 | /* Initialize Initialize buffers. */ | |
507 | buffer_init(&stdin_buffer); | |
508 | buffer_init(&stdout_buffer); | |
509 | buffer_init(&stderr_buffer); | |
510 | ||
511 | /* | |
512 | * If we have no separate fderr (which is the case when we have a pty | |
513 | * - there we cannot make difference between data sent to stdout and | |
514 | * stderr), indicate that we have seen an EOF from stderr. This way | |
515 | * we don\'t need to check the descriptor everywhere. | |
516 | */ | |
517 | if (fderr == -1) | |
518 | fderr_eof = 1; | |
519 | ||
520 | server_init_dispatch(); | |
521 | ||
522 | /* Main loop of the server for the interactive session mode. */ | |
523 | for (;;) { | |
524 | ||
525 | /* Process buffered packets from the client. */ | |
526 | process_buffered_input_packets(); | |
527 | ||
528 | /* | |
529 | * If we have received eof, and there is no more pending | |
530 | * input data, cause a real eof by closing fdin. | |
531 | */ | |
532 | if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { | |
533 | #ifdef USE_PIPES | |
534 | close(fdin); | |
535 | #else | |
536 | if (fdin != fdout) | |
537 | close(fdin); | |
538 | else | |
539 | shutdown(fdin, SHUT_WR); /* We will no longer send. */ | |
540 | #endif | |
541 | fdin = -1; | |
542 | } | |
543 | /* Make packets from buffered stderr data to send to the client. */ | |
544 | make_packets_from_stderr_data(); | |
545 | ||
546 | /* | |
547 | * Make packets from buffered stdout data to send to the | |
548 | * client. If there is very little to send, this arranges to | |
549 | * not send them now, but to wait a short while to see if we | |
550 | * are getting more data. This is necessary, as some systems | |
551 | * wake up readers from a pty after each separate character. | |
552 | */ | |
553 | max_time_milliseconds = 0; | |
554 | stdout_buffer_bytes = buffer_len(&stdout_buffer); | |
555 | if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && | |
556 | stdout_buffer_bytes != previous_stdout_buffer_bytes) { | |
557 | /* try again after a while */ | |
558 | max_time_milliseconds = 10; | |
559 | } else { | |
560 | /* Send it now. */ | |
561 | make_packets_from_stdout_data(); | |
562 | } | |
563 | previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); | |
564 | ||
565 | /* Send channel data to the client. */ | |
566 | if (packet_not_very_much_data_to_write()) | |
567 | channel_output_poll(); | |
568 | ||
569 | /* | |
570 | * Bail out of the loop if the program has closed its output | |
571 | * descriptors, and we have no more data to send to the | |
572 | * client, and there is no pending buffered data. | |
573 | */ | |
574 | if (fdout_eof && fderr_eof && !packet_have_data_to_write() && | |
575 | buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { | |
576 | if (!channel_still_open()) | |
577 | break; | |
578 | if (!waiting_termination) { | |
579 | const char *s = "Waiting for forwarded connections to terminate...\r\n"; | |
580 | char *cp; | |
581 | waiting_termination = 1; | |
582 | buffer_append(&stderr_buffer, s, strlen(s)); | |
583 | ||
584 | /* Display list of open channels. */ | |
585 | cp = channel_open_message(); | |
586 | buffer_append(&stderr_buffer, cp, strlen(cp)); | |
587 | xfree(cp); | |
588 | } | |
589 | } | |
590 | /* Sleep in select() until we can do something. */ | |
591 | wait_until_can_do_something(&readset, &writeset, &max_fd, | |
592 | max_time_milliseconds); | |
593 | ||
594 | /* Process any channel events. */ | |
595 | channel_after_select(readset, writeset); | |
596 | ||
597 | /* Process input from the client and from program stdout/stderr. */ | |
598 | process_input(readset); | |
599 | ||
600 | /* Process output to the client and to program stdin. */ | |
601 | process_output(writeset); | |
602 | } | |
603 | if (readset) | |
604 | xfree(readset); | |
605 | if (writeset) | |
606 | xfree(writeset); | |
607 | ||
608 | /* Cleanup and termination code. */ | |
609 | ||
610 | /* Wait until all output has been sent to the client. */ | |
611 | drain_output(); | |
612 | ||
613 | debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", | |
614 | stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); | |
615 | ||
616 | /* Free and clear the buffers. */ | |
617 | buffer_free(&stdin_buffer); | |
618 | buffer_free(&stdout_buffer); | |
619 | buffer_free(&stderr_buffer); | |
620 | ||
621 | /* Close the file descriptors. */ | |
622 | if (fdout != -1) | |
623 | close(fdout); | |
624 | fdout = -1; | |
625 | fdout_eof = 1; | |
626 | if (fderr != -1) | |
627 | close(fderr); | |
628 | fderr = -1; | |
629 | fderr_eof = 1; | |
630 | if (fdin != -1) | |
631 | close(fdin); | |
632 | fdin = -1; | |
633 | ||
634 | /* Stop listening for channels; this removes unix domain sockets. */ | |
635 | channel_stop_listening(); | |
636 | ||
637 | /* Wait for the child to exit. Get its exit status. */ | |
638 | wait_pid = wait(&wait_status); | |
639 | if (wait_pid == -1) { | |
640 | /* | |
641 | * It is possible that the wait was handled by SIGCHLD | |
642 | * handler. This may result in either: this call | |
643 | * returning with EINTR, or: this call returning ECHILD. | |
644 | */ | |
645 | if (child_terminated) | |
646 | wait_status = child_wait_status; | |
647 | else | |
648 | packet_disconnect("wait: %.100s", strerror(errno)); | |
649 | } else { | |
650 | /* Check if it matches the process we forked. */ | |
651 | if (wait_pid != pid) | |
652 | error("Strange, wait returned pid %d, expected %d", | |
653 | wait_pid, pid); | |
654 | } | |
655 | ||
656 | /* We no longer want our SIGCHLD handler to be called. */ | |
657 | signal(SIGCHLD, SIG_DFL); | |
658 | ||
659 | /* Check if it exited normally. */ | |
660 | if (WIFEXITED(wait_status)) { | |
661 | /* Yes, normal exit. Get exit status and send it to the client. */ | |
662 | debug("Command exited with status %d.", WEXITSTATUS(wait_status)); | |
663 | packet_start(SSH_SMSG_EXITSTATUS); | |
664 | packet_put_int(WEXITSTATUS(wait_status)); | |
665 | packet_send(); | |
666 | packet_write_wait(); | |
667 | ||
668 | /* | |
669 | * Wait for exit confirmation. Note that there might be | |
670 | * other packets coming before it; however, the program has | |
671 | * already died so we just ignore them. The client is | |
672 | * supposed to respond with the confirmation when it receives | |
673 | * the exit status. | |
674 | */ | |
675 | do { | |
676 | int plen; | |
677 | type = packet_read(&plen); | |
678 | } | |
679 | while (type != SSH_CMSG_EXIT_CONFIRMATION); | |
680 | ||
681 | debug("Received exit confirmation."); | |
682 | return; | |
683 | } | |
684 | /* Check if the program terminated due to a signal. */ | |
685 | if (WIFSIGNALED(wait_status)) | |
686 | packet_disconnect("Command terminated on signal %d.", | |
687 | WTERMSIG(wait_status)); | |
688 | ||
689 | /* Some weird exit cause. Just exit. */ | |
690 | packet_disconnect("wait returned status %04x.", wait_status); | |
691 | /* NOTREACHED */ | |
692 | } | |
693 | ||
694 | void | |
695 | server_loop2(void) | |
696 | { | |
697 | fd_set *readset = NULL, *writeset = NULL; | |
698 | int rekeying = 0, max_fd, status; | |
699 | pid_t pid; | |
700 | ||
701 | debug("Entering interactive session for SSH2."); | |
702 | ||
703 | mysignal(SIGCHLD, sigchld_handler2); | |
704 | child_terminated = 0; | |
705 | connection_in = packet_get_connection_in(); | |
706 | connection_out = packet_get_connection_out(); | |
707 | ||
708 | max_fd = MAX(connection_in, connection_out); | |
709 | ||
710 | server_init_dispatch(); | |
711 | ||
712 | for (;;) { | |
713 | process_buffered_input_packets(); | |
714 | ||
715 | rekeying = (xxx_kex != NULL && !xxx_kex->done); | |
716 | ||
717 | if (!rekeying && packet_not_very_much_data_to_write()) | |
718 | channel_output_poll(); | |
719 | wait_until_can_do_something(&readset, &writeset, &max_fd, | |
720 | rekeying); | |
721 | if (child_terminated) { | |
722 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0) | |
723 | session_close_by_pid(pid, status); | |
724 | child_terminated = 0; | |
725 | } | |
726 | if (!rekeying) | |
727 | channel_after_select(readset, writeset); | |
728 | process_input(readset); | |
729 | if (connection_closed) | |
730 | break; | |
731 | process_output(writeset); | |
732 | } | |
733 | if (readset) | |
734 | xfree(readset); | |
735 | if (writeset) | |
736 | xfree(writeset); | |
737 | ||
738 | signal(SIGCHLD, SIG_DFL); | |
739 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0) | |
740 | session_close_by_pid(pid, status); | |
741 | channel_stop_listening(); | |
742 | } | |
743 | ||
744 | void | |
745 | server_input_channel_failure(int type, int plen, void *ctxt) | |
746 | { | |
747 | debug("Got CHANNEL_FAILURE for keepalive"); | |
748 | /* | |
749 | * reset timeout, since we got a sane answer from the client. | |
750 | * even if this was generated by something other than | |
751 | * the bogus CHANNEL_REQUEST we send for keepalives. | |
752 | */ | |
753 | client_alive_timeouts = 0; | |
754 | } | |
755 | ||
756 | ||
757 | void | |
758 | server_input_stdin_data(int type, int plen, void *ctxt) | |
759 | { | |
760 | char *data; | |
761 | u_int data_len; | |
762 | ||
763 | /* Stdin data from the client. Append it to the buffer. */ | |
764 | /* Ignore any data if the client has closed stdin. */ | |
765 | if (fdin == -1) | |
766 | return; | |
767 | data = packet_get_string(&data_len); | |
768 | packet_integrity_check(plen, (4 + data_len), type); | |
769 | buffer_append(&stdin_buffer, data, data_len); | |
770 | memset(data, 0, data_len); | |
771 | xfree(data); | |
772 | } | |
773 | ||
774 | void | |
775 | server_input_eof(int type, int plen, void *ctxt) | |
776 | { | |
777 | /* | |
778 | * Eof from the client. The stdin descriptor to the | |
779 | * program will be closed when all buffered data has | |
780 | * drained. | |
781 | */ | |
782 | debug("EOF received for stdin."); | |
783 | packet_integrity_check(plen, 0, type); | |
784 | stdin_eof = 1; | |
785 | } | |
786 | ||
787 | void | |
788 | server_input_window_size(int type, int plen, void *ctxt) | |
789 | { | |
790 | int row = packet_get_int(); | |
791 | int col = packet_get_int(); | |
792 | int xpixel = packet_get_int(); | |
793 | int ypixel = packet_get_int(); | |
794 | ||
795 | debug("Window change received."); | |
796 | packet_integrity_check(plen, 4 * 4, type); | |
797 | if (fdin != -1) | |
798 | pty_change_window_size(fdin, row, col, xpixel, ypixel); | |
799 | } | |
800 | ||
801 | Channel * | |
802 | server_request_direct_tcpip(char *ctype) | |
803 | { | |
804 | int sock, newch; | |
805 | char *target, *originator; | |
806 | int target_port, originator_port; | |
807 | ||
808 | target = packet_get_string(NULL); | |
809 | target_port = packet_get_int(); | |
810 | originator = packet_get_string(NULL); | |
811 | originator_port = packet_get_int(); | |
812 | packet_done(); | |
813 | ||
814 | debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", | |
815 | originator, originator_port, target, target_port); | |
816 | ||
817 | /* XXX check permission */ | |
818 | sock = channel_connect_to(target, target_port); | |
819 | xfree(target); | |
820 | xfree(originator); | |
821 | if (sock < 0) | |
822 | return NULL; | |
823 | newch = channel_new(ctype, SSH_CHANNEL_CONNECTING, | |
824 | sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, | |
825 | CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1); | |
826 | return (newch >= 0) ? channel_lookup(newch) : NULL; | |
827 | } | |
828 | ||
829 | Channel * | |
830 | server_request_session(char *ctype) | |
831 | { | |
832 | int newch; | |
833 | ||
834 | debug("input_session_request"); | |
835 | packet_done(); | |
836 | /* | |
837 | * A server session has no fd to read or write until a | |
838 | * CHANNEL_REQUEST for a shell is made, so we set the type to | |
839 | * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all | |
840 | * CHANNEL_REQUEST messages is registered. | |
841 | */ | |
842 | newch = channel_new(ctype, SSH_CHANNEL_LARVAL, | |
843 | -1, -1, -1, 0, CHAN_SES_PACKET_DEFAULT, | |
844 | 0, xstrdup("server-session"), 1); | |
845 | if (session_open(newch) == 1) { | |
846 | channel_register_callback(newch, SSH2_MSG_CHANNEL_REQUEST, | |
847 | session_input_channel_req, (void *)0); | |
848 | channel_register_cleanup(newch, session_close_by_channel); | |
849 | return channel_lookup(newch); | |
850 | } else { | |
851 | debug("session open failed, free channel %d", newch); | |
852 | channel_free(newch); | |
853 | } | |
854 | return NULL; | |
855 | } | |
856 | ||
857 | void | |
858 | server_input_channel_open(int type, int plen, void *ctxt) | |
859 | { | |
860 | Channel *c = NULL; | |
861 | char *ctype; | |
862 | u_int len; | |
863 | int rchan; | |
864 | int rmaxpack; | |
865 | int rwindow; | |
866 | ||
867 | ctype = packet_get_string(&len); | |
868 | rchan = packet_get_int(); | |
869 | rwindow = packet_get_int(); | |
870 | rmaxpack = packet_get_int(); | |
871 | ||
872 | debug("server_input_channel_open: ctype %s rchan %d win %d max %d", | |
873 | ctype, rchan, rwindow, rmaxpack); | |
874 | ||
875 | if (strcmp(ctype, "session") == 0) { | |
876 | c = server_request_session(ctype); | |
877 | } else if (strcmp(ctype, "direct-tcpip") == 0) { | |
878 | c = server_request_direct_tcpip(ctype); | |
879 | } | |
880 | if (c != NULL) { | |
881 | debug("server_input_channel_open: confirm %s", ctype); | |
882 | c->remote_id = rchan; | |
883 | c->remote_window = rwindow; | |
884 | c->remote_maxpacket = rmaxpack; | |
885 | ||
886 | packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); | |
887 | packet_put_int(c->remote_id); | |
888 | packet_put_int(c->self); | |
889 | packet_put_int(c->local_window); | |
890 | packet_put_int(c->local_maxpacket); | |
891 | packet_send(); | |
892 | } else { | |
893 | debug("server_input_channel_open: failure %s", ctype); | |
894 | packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); | |
895 | packet_put_int(rchan); | |
896 | packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); | |
897 | if (!(datafellows & SSH_BUG_OPENFAILURE)) { | |
898 | packet_put_cstring("bla bla"); | |
899 | packet_put_cstring(""); | |
900 | } | |
901 | packet_send(); | |
902 | } | |
903 | xfree(ctype); | |
904 | } | |
905 | ||
906 | void | |
907 | server_input_global_request(int type, int plen, void *ctxt) | |
908 | { | |
909 | char *rtype; | |
910 | int want_reply; | |
911 | int success = 0; | |
912 | ||
913 | rtype = packet_get_string(NULL); | |
914 | want_reply = packet_get_char(); | |
915 | debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); | |
916 | ||
917 | /* -R style forwarding */ | |
918 | if (strcmp(rtype, "tcpip-forward") == 0) { | |
919 | struct passwd *pw; | |
920 | char *listen_address; | |
921 | u_short listen_port; | |
922 | ||
923 | pw = auth_get_user(); | |
924 | if (pw == NULL) | |
925 | fatal("server_input_global_request: no user"); | |
926 | listen_address = packet_get_string(NULL); /* XXX currently ignored */ | |
927 | listen_port = (u_short)packet_get_int(); | |
928 | debug("server_input_global_request: tcpip-forward listen %s port %d", | |
929 | listen_address, listen_port); | |
930 | ||
931 | /* check permissions */ | |
932 | if (!options.allow_tcp_forwarding || | |
933 | no_port_forwarding_flag || | |
934 | (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { | |
935 | success = 0; | |
936 | packet_send_debug("Server has disabled port forwarding."); | |
937 | } else { | |
938 | /* Start listening on the port */ | |
939 | success = channel_request_forwarding( | |
940 | listen_address, listen_port, | |
941 | /*unspec host_to_connect*/ "<unspec host>", | |
942 | /*unspec port_to_connect*/ 0, | |
943 | options.gateway_ports, /*remote*/ 1); | |
944 | } | |
945 | xfree(listen_address); | |
946 | } | |
947 | if (want_reply) { | |
948 | packet_start(success ? | |
949 | SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); | |
950 | packet_send(); | |
951 | packet_write_wait(); | |
952 | } | |
953 | xfree(rtype); | |
954 | } | |
955 | ||
956 | void | |
957 | server_init_dispatch_20(void) | |
958 | { | |
959 | debug("server_init_dispatch_20"); | |
960 | dispatch_init(&dispatch_protocol_error); | |
961 | dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); | |
962 | dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); | |
963 | dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); | |
964 | dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); | |
965 | dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); | |
966 | dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); | |
967 | dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); | |
968 | dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &channel_input_channel_request); | |
969 | dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); | |
970 | dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); | |
971 | /* client_alive */ | |
972 | dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure); | |
973 | /* rekeying */ | |
974 | dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); | |
975 | } | |
976 | void | |
977 | server_init_dispatch_13(void) | |
978 | { | |
979 | debug("server_init_dispatch_13"); | |
980 | dispatch_init(NULL); | |
981 | dispatch_set(SSH_CMSG_EOF, &server_input_eof); | |
982 | dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); | |
983 | dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); | |
984 | dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); | |
985 | dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); | |
986 | dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); | |
987 | dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); | |
988 | dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); | |
989 | dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); | |
990 | } | |
991 | void | |
992 | server_init_dispatch_15(void) | |
993 | { | |
994 | server_init_dispatch_13(); | |
995 | debug("server_init_dispatch_15"); | |
996 | dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); | |
997 | dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); | |
998 | } | |
999 | void | |
1000 | server_init_dispatch(void) | |
1001 | { | |
1002 | if (compat20) | |
1003 | server_init_dispatch_20(); | |
1004 | else if (compat13) | |
1005 | server_init_dispatch_13(); | |
1006 | else | |
1007 | server_init_dispatch_15(); | |
1008 | } | |
1009 |