]>
Commit | Line | Data |
---|---|---|
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 1.54 2001/03/04 01:46:30 djm 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 | ||
57 | extern ServerOptions options; | |
58 | ||
59 | static Buffer stdin_buffer; /* Buffer for stdin data. */ | |
60 | static Buffer stdout_buffer; /* Buffer for stdout data. */ | |
61 | static Buffer stderr_buffer; /* Buffer for stderr data. */ | |
62 | static int fdin; /* Descriptor for stdin (for writing) */ | |
63 | static int fdout; /* Descriptor for stdout (for reading); | |
64 | May be same number as fdin. */ | |
65 | static int fderr; /* Descriptor for stderr. May be -1. */ | |
66 | static long stdin_bytes = 0; /* Number of bytes written to stdin. */ | |
67 | static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ | |
68 | static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ | |
69 | static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ | |
70 | static int stdin_eof = 0; /* EOF message received from client. */ | |
71 | static int fdout_eof = 0; /* EOF encountered reading from fdout. */ | |
72 | static int fderr_eof = 0; /* EOF encountered readung from fderr. */ | |
73 | static int fdin_is_tty = 0; /* fdin points to a tty. */ | |
74 | static int connection_in; /* Connection to client (input). */ | |
75 | static int connection_out; /* Connection to client (output). */ | |
76 | static u_int buffer_high;/* "Soft" max buffer size. */ | |
77 | ||
78 | /* | |
79 | * This SIGCHLD kludge is used to detect when the child exits. The server | |
80 | * will exit after that, as soon as forwarded connections have terminated. | |
81 | */ | |
82 | ||
83 | static pid_t child_pid; /* Pid of the child. */ | |
84 | static volatile int child_terminated; /* The child has terminated. */ | |
85 | static volatile int child_wait_status; /* Status from wait(). */ | |
86 | ||
87 | void server_init_dispatch(void); | |
88 | ||
89 | void | |
90 | sigchld_handler(int sig) | |
91 | { | |
92 | int save_errno = errno; | |
93 | pid_t wait_pid; | |
94 | ||
95 | debug("Received SIGCHLD."); | |
96 | wait_pid = wait((int *) &child_wait_status); | |
97 | if (wait_pid != -1) { | |
98 | if (wait_pid != child_pid) | |
99 | error("Strange, got SIGCHLD and wait returned pid %d but child is %d", | |
100 | wait_pid, child_pid); | |
101 | if (WIFEXITED(child_wait_status) || | |
102 | WIFSIGNALED(child_wait_status)) | |
103 | child_terminated = 1; | |
104 | } | |
105 | signal(SIGCHLD, sigchld_handler); | |
106 | errno = save_errno; | |
107 | } | |
108 | void | |
109 | sigchld_handler2(int sig) | |
110 | { | |
111 | int save_errno = errno; | |
112 | debug("Received SIGCHLD."); | |
113 | child_terminated = 1; | |
114 | mysignal(SIGCHLD, sigchld_handler2); | |
115 | errno = save_errno; | |
116 | } | |
117 | ||
118 | /* | |
119 | * Make packets from buffered stderr data, and buffer it for sending | |
120 | * to the client. | |
121 | */ | |
122 | void | |
123 | make_packets_from_stderr_data(void) | |
124 | { | |
125 | int len; | |
126 | ||
127 | /* Send buffered stderr data to the client. */ | |
128 | while (buffer_len(&stderr_buffer) > 0 && | |
129 | packet_not_very_much_data_to_write()) { | |
130 | len = buffer_len(&stderr_buffer); | |
131 | if (packet_is_interactive()) { | |
132 | if (len > 512) | |
133 | len = 512; | |
134 | } else { | |
135 | /* Keep the packets at reasonable size. */ | |
136 | if (len > packet_get_maxsize()) | |
137 | len = packet_get_maxsize(); | |
138 | } | |
139 | packet_start(SSH_SMSG_STDERR_DATA); | |
140 | packet_put_string(buffer_ptr(&stderr_buffer), len); | |
141 | packet_send(); | |
142 | buffer_consume(&stderr_buffer, len); | |
143 | stderr_bytes += len; | |
144 | } | |
145 | } | |
146 | ||
147 | /* | |
148 | * Make packets from buffered stdout data, and buffer it for sending to the | |
149 | * client. | |
150 | */ | |
151 | void | |
152 | make_packets_from_stdout_data(void) | |
153 | { | |
154 | int len; | |
155 | ||
156 | /* Send buffered stdout data to the client. */ | |
157 | while (buffer_len(&stdout_buffer) > 0 && | |
158 | packet_not_very_much_data_to_write()) { | |
159 | len = buffer_len(&stdout_buffer); | |
160 | if (packet_is_interactive()) { | |
161 | if (len > 512) | |
162 | len = 512; | |
163 | } else { | |
164 | /* Keep the packets at reasonable size. */ | |
165 | if (len > packet_get_maxsize()) | |
166 | len = packet_get_maxsize(); | |
167 | } | |
168 | packet_start(SSH_SMSG_STDOUT_DATA); | |
169 | packet_put_string(buffer_ptr(&stdout_buffer), len); | |
170 | packet_send(); | |
171 | buffer_consume(&stdout_buffer, len); | |
172 | stdout_bytes += len; | |
173 | } | |
174 | } | |
175 | ||
176 | /* | |
177 | * Sleep in select() until we can do something. This will initialize the | |
178 | * select masks. Upon return, the masks will indicate which descriptors | |
179 | * have data or can accept data. Optionally, a maximum time can be specified | |
180 | * for the duration of the wait (0 = infinite). | |
181 | */ | |
182 | void | |
183 | wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, | |
184 | u_int max_time_milliseconds) | |
185 | { | |
186 | struct timeval tv, *tvp; | |
187 | int ret; | |
188 | ||
189 | /* When select fails we restart from here. */ | |
190 | retry_select: | |
191 | ||
192 | /* Allocate and update select() masks for channel descriptors. */ | |
193 | channel_prepare_select(readsetp, writesetp, maxfdp); | |
194 | ||
195 | if (compat20) { | |
196 | /* wrong: bad condition XXX */ | |
197 | if (channel_not_very_much_buffered_data()) | |
198 | FD_SET(connection_in, *readsetp); | |
199 | } else { | |
200 | /* | |
201 | * Read packets from the client unless we have too much | |
202 | * buffered stdin or channel data. | |
203 | */ | |
204 | if (buffer_len(&stdin_buffer) < buffer_high && | |
205 | channel_not_very_much_buffered_data()) | |
206 | FD_SET(connection_in, *readsetp); | |
207 | /* | |
208 | * If there is not too much data already buffered going to | |
209 | * the client, try to get some more data from the program. | |
210 | */ | |
211 | if (packet_not_very_much_data_to_write()) { | |
212 | if (!fdout_eof) | |
213 | FD_SET(fdout, *readsetp); | |
214 | if (!fderr_eof) | |
215 | FD_SET(fderr, *readsetp); | |
216 | } | |
217 | /* | |
218 | * If we have buffered data, try to write some of that data | |
219 | * to the program. | |
220 | */ | |
221 | if (fdin != -1 && buffer_len(&stdin_buffer) > 0) | |
222 | FD_SET(fdin, *writesetp); | |
223 | } | |
224 | ||
225 | /* | |
226 | * If we have buffered packet data going to the client, mark that | |
227 | * descriptor. | |
228 | */ | |
229 | if (packet_have_data_to_write()) | |
230 | FD_SET(connection_out, *writesetp); | |
231 | ||
232 | /* | |
233 | * If child has terminated and there is enough buffer space to read | |
234 | * from it, then read as much as is available and exit. | |
235 | */ | |
236 | if (child_terminated && packet_not_very_much_data_to_write()) | |
237 | if (max_time_milliseconds == 0) | |
238 | max_time_milliseconds = 100; | |
239 | ||
240 | if (max_time_milliseconds == 0) | |
241 | tvp = NULL; | |
242 | else { | |
243 | tv.tv_sec = max_time_milliseconds / 1000; | |
244 | tv.tv_usec = 1000 * (max_time_milliseconds % 1000); | |
245 | tvp = &tv; | |
246 | } | |
247 | if (tvp!=NULL) | |
248 | debug3("tvp!=NULL kid %d mili %d", child_terminated, max_time_milliseconds); | |
249 | ||
250 | /* Wait for something to happen, or the timeout to expire. */ | |
251 | ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); | |
252 | ||
253 | if (ret < 0) { | |
254 | if (errno != EINTR) | |
255 | error("select: %.100s", strerror(errno)); | |
256 | else | |
257 | goto retry_select; | |
258 | } | |
259 | } | |
260 | ||
261 | /* | |
262 | * Processes input from the client and the program. Input data is stored | |
263 | * in buffers and processed later. | |
264 | */ | |
265 | void | |
266 | process_input(fd_set * readset) | |
267 | { | |
268 | int len; | |
269 | char buf[16384]; | |
270 | ||
271 | /* Read and buffer any input data from the client. */ | |
272 | if (FD_ISSET(connection_in, readset)) { | |
273 | len = read(connection_in, buf, sizeof(buf)); | |
274 | if (len == 0) { | |
275 | verbose("Connection closed by remote host."); | |
276 | fatal_cleanup(); | |
277 | } else if (len < 0) { | |
278 | if (errno != EINTR && errno != EAGAIN) { | |
279 | verbose("Read error from remote host: %.100s", strerror(errno)); | |
280 | fatal_cleanup(); | |
281 | } | |
282 | } else { | |
283 | /* Buffer any received data. */ | |
284 | packet_process_incoming(buf, len); | |
285 | } | |
286 | } | |
287 | if (compat20) | |
288 | return; | |
289 | ||
290 | /* Read and buffer any available stdout data from the program. */ | |
291 | if (!fdout_eof && FD_ISSET(fdout, readset)) { | |
292 | len = read(fdout, buf, sizeof(buf)); | |
293 | if (len < 0 && (errno == EINTR || errno == EAGAIN)) { | |
294 | /* do nothing */ | |
295 | } else if (len <= 0) { | |
296 | fdout_eof = 1; | |
297 | } else { | |
298 | buffer_append(&stdout_buffer, buf, len); | |
299 | fdout_bytes += len; | |
300 | } | |
301 | } | |
302 | /* Read and buffer any available stderr data from the program. */ | |
303 | if (!fderr_eof && FD_ISSET(fderr, readset)) { | |
304 | len = read(fderr, buf, sizeof(buf)); | |
305 | if (len < 0 && (errno == EINTR || errno == EAGAIN)) { | |
306 | /* do nothing */ | |
307 | } else if (len <= 0) { | |
308 | fderr_eof = 1; | |
309 | } else { | |
310 | buffer_append(&stderr_buffer, buf, len); | |
311 | } | |
312 | } | |
313 | } | |
314 | ||
315 | /* | |
316 | * Sends data from internal buffers to client program stdin. | |
317 | */ | |
318 | void | |
319 | process_output(fd_set * writeset) | |
320 | { | |
321 | struct termios tio; | |
322 | int len; | |
323 | ||
324 | /* Write buffered data to program stdin. */ | |
325 | if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { | |
326 | len = write(fdin, buffer_ptr(&stdin_buffer), | |
327 | buffer_len(&stdin_buffer)); | |
328 | if (len < 0 && (errno == EINTR || errno == EAGAIN)) { | |
329 | /* do nothing */ | |
330 | } else if (len <= 0) { | |
331 | #ifdef USE_PIPES | |
332 | close(fdin); | |
333 | #else | |
334 | if (fdin != fdout) | |
335 | close(fdin); | |
336 | else | |
337 | shutdown(fdin, SHUT_WR); /* We will no longer send. */ | |
338 | #endif | |
339 | fdin = -1; | |
340 | } else { | |
341 | /* Successful write. */ | |
342 | if (fdin_is_tty && tcgetattr(fdin, &tio) == 0 && | |
343 | !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { | |
344 | /* | |
345 | * Simulate echo to reduce the impact of | |
346 | * traffic analysis | |
347 | */ | |
348 | packet_send_ignore(len); | |
349 | packet_send(); | |
350 | } | |
351 | /* Consume the data from the buffer. */ | |
352 | buffer_consume(&stdin_buffer, len); | |
353 | /* Update the count of bytes written to the program. */ | |
354 | stdin_bytes += len; | |
355 | } | |
356 | } | |
357 | /* Send any buffered packet data to the client. */ | |
358 | if (FD_ISSET(connection_out, writeset)) | |
359 | packet_write_poll(); | |
360 | } | |
361 | ||
362 | /* | |
363 | * Wait until all buffered output has been sent to the client. | |
364 | * This is used when the program terminates. | |
365 | */ | |
366 | void | |
367 | drain_output(void) | |
368 | { | |
369 | /* Send any buffered stdout data to the client. */ | |
370 | if (buffer_len(&stdout_buffer) > 0) { | |
371 | packet_start(SSH_SMSG_STDOUT_DATA); | |
372 | packet_put_string(buffer_ptr(&stdout_buffer), | |
373 | buffer_len(&stdout_buffer)); | |
374 | packet_send(); | |
375 | /* Update the count of sent bytes. */ | |
376 | stdout_bytes += buffer_len(&stdout_buffer); | |
377 | } | |
378 | /* Send any buffered stderr data to the client. */ | |
379 | if (buffer_len(&stderr_buffer) > 0) { | |
380 | packet_start(SSH_SMSG_STDERR_DATA); | |
381 | packet_put_string(buffer_ptr(&stderr_buffer), | |
382 | buffer_len(&stderr_buffer)); | |
383 | packet_send(); | |
384 | /* Update the count of sent bytes. */ | |
385 | stderr_bytes += buffer_len(&stderr_buffer); | |
386 | } | |
387 | /* Wait until all buffered data has been written to the client. */ | |
388 | packet_write_wait(); | |
389 | } | |
390 | ||
391 | void | |
392 | process_buffered_input_packets(void) | |
393 | { | |
394 | dispatch_run(DISPATCH_NONBLOCK, NULL, NULL); | |
395 | } | |
396 | ||
397 | /* | |
398 | * Performs the interactive session. This handles data transmission between | |
399 | * the client and the program. Note that the notion of stdin, stdout, and | |
400 | * stderr in this function is sort of reversed: this function writes to | |
401 | * stdin (of the child program), and reads from stdout and stderr (of the | |
402 | * child program). | |
403 | */ | |
404 | void | |
405 | server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) | |
406 | { | |
407 | fd_set *readset = NULL, *writeset = NULL; | |
408 | int max_fd; | |
409 | int wait_status; /* Status returned by wait(). */ | |
410 | pid_t wait_pid; /* pid returned by wait(). */ | |
411 | int waiting_termination = 0; /* Have displayed waiting close message. */ | |
412 | u_int max_time_milliseconds; | |
413 | u_int previous_stdout_buffer_bytes; | |
414 | u_int stdout_buffer_bytes; | |
415 | int type; | |
416 | ||
417 | debug("Entering interactive session."); | |
418 | ||
419 | /* Initialize the SIGCHLD kludge. */ | |
420 | child_pid = pid; | |
421 | child_terminated = 0; | |
422 | signal(SIGCHLD, sigchld_handler); | |
423 | signal(SIGPIPE, SIG_IGN); | |
424 | ||
425 | /* Initialize our global variables. */ | |
426 | fdin = fdin_arg; | |
427 | fdout = fdout_arg; | |
428 | fderr = fderr_arg; | |
429 | ||
430 | /* nonblocking IO */ | |
431 | set_nonblock(fdin); | |
432 | set_nonblock(fdout); | |
433 | /* we don't have stderr for interactive terminal sessions, see below */ | |
434 | if (fderr != -1) | |
435 | set_nonblock(fderr); | |
436 | ||
437 | if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) | |
438 | fdin_is_tty = 1; | |
439 | ||
440 | connection_in = packet_get_connection_in(); | |
441 | connection_out = packet_get_connection_out(); | |
442 | ||
443 | previous_stdout_buffer_bytes = 0; | |
444 | ||
445 | /* Set approximate I/O buffer size. */ | |
446 | if (packet_is_interactive()) | |
447 | buffer_high = 4096; | |
448 | else | |
449 | buffer_high = 64 * 1024; | |
450 | ||
451 | /* Initialize max_fd to the maximum of the known file descriptors. */ | |
452 | max_fd = MAX(fdin, fdout); | |
453 | if (fderr != -1) | |
454 | max_fd = MAX(max_fd, fderr); | |
455 | max_fd = MAX(max_fd, connection_in); | |
456 | max_fd = MAX(max_fd, connection_out); | |
457 | ||
458 | /* Initialize Initialize buffers. */ | |
459 | buffer_init(&stdin_buffer); | |
460 | buffer_init(&stdout_buffer); | |
461 | buffer_init(&stderr_buffer); | |
462 | ||
463 | /* | |
464 | * If we have no separate fderr (which is the case when we have a pty | |
465 | * - there we cannot make difference between data sent to stdout and | |
466 | * stderr), indicate that we have seen an EOF from stderr. This way | |
467 | * we don\'t need to check the descriptor everywhere. | |
468 | */ | |
469 | if (fderr == -1) | |
470 | fderr_eof = 1; | |
471 | ||
472 | server_init_dispatch(); | |
473 | ||
474 | /* Main loop of the server for the interactive session mode. */ | |
475 | for (;;) { | |
476 | ||
477 | /* Process buffered packets from the client. */ | |
478 | process_buffered_input_packets(); | |
479 | ||
480 | /* | |
481 | * If we have received eof, and there is no more pending | |
482 | * input data, cause a real eof by closing fdin. | |
483 | */ | |
484 | if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { | |
485 | #ifdef USE_PIPES | |
486 | close(fdin); | |
487 | #else | |
488 | if (fdin != fdout) | |
489 | close(fdin); | |
490 | else | |
491 | shutdown(fdin, SHUT_WR); /* We will no longer send. */ | |
492 | #endif | |
493 | fdin = -1; | |
494 | } | |
495 | /* Make packets from buffered stderr data to send to the client. */ | |
496 | make_packets_from_stderr_data(); | |
497 | ||
498 | /* | |
499 | * Make packets from buffered stdout data to send to the | |
500 | * client. If there is very little to send, this arranges to | |
501 | * not send them now, but to wait a short while to see if we | |
502 | * are getting more data. This is necessary, as some systems | |
503 | * wake up readers from a pty after each separate character. | |
504 | */ | |
505 | max_time_milliseconds = 0; | |
506 | stdout_buffer_bytes = buffer_len(&stdout_buffer); | |
507 | if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && | |
508 | stdout_buffer_bytes != previous_stdout_buffer_bytes) { | |
509 | /* try again after a while */ | |
510 | max_time_milliseconds = 10; | |
511 | } else { | |
512 | /* Send it now. */ | |
513 | make_packets_from_stdout_data(); | |
514 | } | |
515 | previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); | |
516 | ||
517 | /* Send channel data to the client. */ | |
518 | if (packet_not_very_much_data_to_write()) | |
519 | channel_output_poll(); | |
520 | ||
521 | /* | |
522 | * Bail out of the loop if the program has closed its output | |
523 | * descriptors, and we have no more data to send to the | |
524 | * client, and there is no pending buffered data. | |
525 | */ | |
526 | if (fdout_eof && fderr_eof && !packet_have_data_to_write() && | |
527 | buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { | |
528 | if (!channel_still_open()) | |
529 | break; | |
530 | if (!waiting_termination) { | |
531 | const char *s = "Waiting for forwarded connections to terminate...\r\n"; | |
532 | char *cp; | |
533 | waiting_termination = 1; | |
534 | buffer_append(&stderr_buffer, s, strlen(s)); | |
535 | ||
536 | /* Display list of open channels. */ | |
537 | cp = channel_open_message(); | |
538 | buffer_append(&stderr_buffer, cp, strlen(cp)); | |
539 | xfree(cp); | |
540 | } | |
541 | } | |
542 | /* Sleep in select() until we can do something. */ | |
543 | wait_until_can_do_something(&readset, &writeset, &max_fd, | |
544 | max_time_milliseconds); | |
545 | ||
546 | /* Process any channel events. */ | |
547 | channel_after_select(readset, writeset); | |
548 | ||
549 | /* Process input from the client and from program stdout/stderr. */ | |
550 | process_input(readset); | |
551 | ||
552 | /* Process output to the client and to program stdin. */ | |
553 | process_output(writeset); | |
554 | } | |
555 | if (readset) | |
556 | xfree(readset); | |
557 | if (writeset) | |
558 | xfree(writeset); | |
559 | ||
560 | /* Cleanup and termination code. */ | |
561 | ||
562 | /* Wait until all output has been sent to the client. */ | |
563 | drain_output(); | |
564 | ||
565 | debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", | |
566 | stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); | |
567 | ||
568 | /* Free and clear the buffers. */ | |
569 | buffer_free(&stdin_buffer); | |
570 | buffer_free(&stdout_buffer); | |
571 | buffer_free(&stderr_buffer); | |
572 | ||
573 | /* Close the file descriptors. */ | |
574 | if (fdout != -1) | |
575 | close(fdout); | |
576 | fdout = -1; | |
577 | fdout_eof = 1; | |
578 | if (fderr != -1) | |
579 | close(fderr); | |
580 | fderr = -1; | |
581 | fderr_eof = 1; | |
582 | if (fdin != -1) | |
583 | close(fdin); | |
584 | fdin = -1; | |
585 | ||
586 | /* Stop listening for channels; this removes unix domain sockets. */ | |
587 | channel_stop_listening(); | |
588 | ||
589 | /* Wait for the child to exit. Get its exit status. */ | |
590 | wait_pid = wait(&wait_status); | |
591 | if (wait_pid == -1) { | |
592 | /* | |
593 | * It is possible that the wait was handled by SIGCHLD | |
594 | * handler. This may result in either: this call | |
595 | * returning with EINTR, or: this call returning ECHILD. | |
596 | */ | |
597 | if (child_terminated) | |
598 | wait_status = child_wait_status; | |
599 | else | |
600 | packet_disconnect("wait: %.100s", strerror(errno)); | |
601 | } else { | |
602 | /* Check if it matches the process we forked. */ | |
603 | if (wait_pid != pid) | |
604 | error("Strange, wait returned pid %d, expected %d", | |
605 | wait_pid, pid); | |
606 | } | |
607 | ||
608 | /* We no longer want our SIGCHLD handler to be called. */ | |
609 | signal(SIGCHLD, SIG_DFL); | |
610 | ||
611 | /* Check if it exited normally. */ | |
612 | if (WIFEXITED(wait_status)) { | |
613 | /* Yes, normal exit. Get exit status and send it to the client. */ | |
614 | debug("Command exited with status %d.", WEXITSTATUS(wait_status)); | |
615 | packet_start(SSH_SMSG_EXITSTATUS); | |
616 | packet_put_int(WEXITSTATUS(wait_status)); | |
617 | packet_send(); | |
618 | packet_write_wait(); | |
619 | ||
620 | /* | |
621 | * Wait for exit confirmation. Note that there might be | |
622 | * other packets coming before it; however, the program has | |
623 | * already died so we just ignore them. The client is | |
624 | * supposed to respond with the confirmation when it receives | |
625 | * the exit status. | |
626 | */ | |
627 | do { | |
628 | int plen; | |
629 | type = packet_read(&plen); | |
630 | } | |
631 | while (type != SSH_CMSG_EXIT_CONFIRMATION); | |
632 | ||
633 | debug("Received exit confirmation."); | |
634 | return; | |
635 | } | |
636 | /* Check if the program terminated due to a signal. */ | |
637 | if (WIFSIGNALED(wait_status)) | |
638 | packet_disconnect("Command terminated on signal %d.", | |
639 | WTERMSIG(wait_status)); | |
640 | ||
641 | /* Some weird exit cause. Just exit. */ | |
642 | packet_disconnect("wait returned status %04x.", wait_status); | |
643 | /* NOTREACHED */ | |
644 | } | |
645 | ||
646 | void | |
647 | server_loop2(void) | |
648 | { | |
649 | fd_set *readset = NULL, *writeset = NULL; | |
650 | int max_fd; | |
651 | int had_channel = 0; | |
652 | int status; | |
653 | pid_t pid; | |
654 | ||
655 | debug("Entering interactive session for SSH2."); | |
656 | ||
657 | mysignal(SIGCHLD, sigchld_handler2); | |
658 | signal(SIGPIPE, SIG_IGN); | |
659 | child_terminated = 0; | |
660 | connection_in = packet_get_connection_in(); | |
661 | connection_out = packet_get_connection_out(); | |
662 | ||
663 | max_fd = MAX(connection_in, connection_out); | |
664 | ||
665 | server_init_dispatch(); | |
666 | ||
667 | for (;;) { | |
668 | process_buffered_input_packets(); | |
669 | if (!had_channel && channel_still_open()) | |
670 | had_channel = 1; | |
671 | if (had_channel && !channel_still_open()) { | |
672 | debug("!channel_still_open."); | |
673 | break; | |
674 | } | |
675 | if (packet_not_very_much_data_to_write()) | |
676 | channel_output_poll(); | |
677 | wait_until_can_do_something(&readset, &writeset, &max_fd, 0); | |
678 | if (child_terminated) { | |
679 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0) | |
680 | session_close_by_pid(pid, status); | |
681 | child_terminated = 0; | |
682 | } | |
683 | channel_after_select(readset, writeset); | |
684 | process_input(readset); | |
685 | process_output(writeset); | |
686 | } | |
687 | if (readset) | |
688 | xfree(readset); | |
689 | if (writeset) | |
690 | xfree(writeset); | |
691 | ||
692 | signal(SIGCHLD, SIG_DFL); | |
693 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0) | |
694 | session_close_by_pid(pid, status); | |
695 | channel_stop_listening(); | |
696 | } | |
697 | ||
698 | void | |
699 | server_input_stdin_data(int type, int plen, void *ctxt) | |
700 | { | |
701 | char *data; | |
702 | u_int data_len; | |
703 | ||
704 | /* Stdin data from the client. Append it to the buffer. */ | |
705 | /* Ignore any data if the client has closed stdin. */ | |
706 | if (fdin == -1) | |
707 | return; | |
708 | data = packet_get_string(&data_len); | |
709 | packet_integrity_check(plen, (4 + data_len), type); | |
710 | buffer_append(&stdin_buffer, data, data_len); | |
711 | memset(data, 0, data_len); | |
712 | xfree(data); | |
713 | } | |
714 | ||
715 | void | |
716 | server_input_eof(int type, int plen, void *ctxt) | |
717 | { | |
718 | /* | |
719 | * Eof from the client. The stdin descriptor to the | |
720 | * program will be closed when all buffered data has | |
721 | * drained. | |
722 | */ | |
723 | debug("EOF received for stdin."); | |
724 | packet_integrity_check(plen, 0, type); | |
725 | stdin_eof = 1; | |
726 | } | |
727 | ||
728 | void | |
729 | server_input_window_size(int type, int plen, void *ctxt) | |
730 | { | |
731 | int row = packet_get_int(); | |
732 | int col = packet_get_int(); | |
733 | int xpixel = packet_get_int(); | |
734 | int ypixel = packet_get_int(); | |
735 | ||
736 | debug("Window change received."); | |
737 | packet_integrity_check(plen, 4 * 4, type); | |
738 | if (fdin != -1) | |
739 | pty_change_window_size(fdin, row, col, xpixel, ypixel); | |
740 | } | |
741 | ||
742 | Channel * | |
743 | server_request_direct_tcpip(char *ctype) | |
744 | { | |
745 | int sock, newch; | |
746 | char *target, *originator; | |
747 | int target_port, originator_port; | |
748 | ||
749 | target = packet_get_string(NULL); | |
750 | target_port = packet_get_int(); | |
751 | originator = packet_get_string(NULL); | |
752 | originator_port = packet_get_int(); | |
753 | packet_done(); | |
754 | ||
755 | debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", | |
756 | originator, originator_port, target, target_port); | |
757 | ||
758 | /* XXX check permission */ | |
759 | if (no_port_forwarding_flag || !options.allow_tcp_forwarding) { | |
760 | xfree(target); | |
761 | xfree(originator); | |
762 | return NULL; | |
763 | } | |
764 | sock = channel_connect_to(target, target_port); | |
765 | xfree(target); | |
766 | xfree(originator); | |
767 | if (sock < 0) | |
768 | return NULL; | |
769 | newch = channel_new(ctype, SSH_CHANNEL_CONNECTING, | |
770 | sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, | |
771 | CHAN_TCP_PACKET_DEFAULT, 0, xstrdup("direct-tcpip"), 1); | |
772 | return (newch >= 0) ? channel_lookup(newch) : NULL; | |
773 | } | |
774 | ||
775 | Channel * | |
776 | server_request_session(char *ctype) | |
777 | { | |
778 | int newch; | |
779 | ||
780 | debug("input_session_request"); | |
781 | packet_done(); | |
782 | /* | |
783 | * A server session has no fd to read or write until a | |
784 | * CHANNEL_REQUEST for a shell is made, so we set the type to | |
785 | * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all | |
786 | * CHANNEL_REQUEST messages is registered. | |
787 | */ | |
788 | newch = channel_new(ctype, SSH_CHANNEL_LARVAL, | |
789 | -1, -1, -1, 0, CHAN_SES_PACKET_DEFAULT, | |
790 | 0, xstrdup("server-session"), 1); | |
791 | if (session_open(newch) == 1) { | |
792 | channel_register_callback(newch, SSH2_MSG_CHANNEL_REQUEST, | |
793 | session_input_channel_req, (void *)0); | |
794 | channel_register_cleanup(newch, session_close_by_channel); | |
795 | return channel_lookup(newch); | |
796 | } else { | |
797 | debug("session open failed, free channel %d", newch); | |
798 | channel_free(newch); | |
799 | } | |
800 | return NULL; | |
801 | } | |
802 | ||
803 | void | |
804 | server_input_channel_open(int type, int plen, void *ctxt) | |
805 | { | |
806 | Channel *c = NULL; | |
807 | char *ctype; | |
808 | u_int len; | |
809 | int rchan; | |
810 | int rmaxpack; | |
811 | int rwindow; | |
812 | ||
813 | ctype = packet_get_string(&len); | |
814 | rchan = packet_get_int(); | |
815 | rwindow = packet_get_int(); | |
816 | rmaxpack = packet_get_int(); | |
817 | ||
818 | debug("server_input_channel_open: ctype %s rchan %d win %d max %d", | |
819 | ctype, rchan, rwindow, rmaxpack); | |
820 | ||
821 | if (strcmp(ctype, "session") == 0) { | |
822 | c = server_request_session(ctype); | |
823 | } else if (strcmp(ctype, "direct-tcpip") == 0) { | |
824 | c = server_request_direct_tcpip(ctype); | |
825 | } | |
826 | if (c != NULL) { | |
827 | debug("server_input_channel_open: confirm %s", ctype); | |
828 | c->remote_id = rchan; | |
829 | c->remote_window = rwindow; | |
830 | c->remote_maxpacket = rmaxpack; | |
831 | ||
832 | packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); | |
833 | packet_put_int(c->remote_id); | |
834 | packet_put_int(c->self); | |
835 | packet_put_int(c->local_window); | |
836 | packet_put_int(c->local_maxpacket); | |
837 | packet_send(); | |
838 | } else { | |
839 | debug("server_input_channel_open: failure %s", ctype); | |
840 | packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); | |
841 | packet_put_int(rchan); | |
842 | packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); | |
843 | packet_put_cstring("bla bla"); | |
844 | packet_put_cstring(""); | |
845 | packet_send(); | |
846 | } | |
847 | xfree(ctype); | |
848 | } | |
849 | ||
850 | void | |
851 | server_input_global_request(int type, int plen, void *ctxt) | |
852 | { | |
853 | char *rtype; | |
854 | int want_reply; | |
855 | int success = 0; | |
856 | ||
857 | rtype = packet_get_string(NULL); | |
858 | want_reply = packet_get_char(); | |
859 | debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); | |
860 | ||
861 | if (strcmp(rtype, "tcpip-forward") == 0) { | |
862 | struct passwd *pw; | |
863 | char *listen_address; | |
864 | u_short listen_port; | |
865 | ||
866 | pw = auth_get_user(); | |
867 | if (pw == NULL) | |
868 | fatal("server_input_global_request: no user"); | |
869 | listen_address = packet_get_string(NULL); /* XXX currently ignored */ | |
870 | listen_port = (u_short)packet_get_int(); | |
871 | debug("server_input_global_request: tcpip-forward listen %s port %d", | |
872 | listen_address, listen_port); | |
873 | ||
874 | /* check permissions */ | |
875 | if (!options.allow_tcp_forwarding || | |
876 | no_port_forwarding_flag || | |
877 | (listen_port < IPPORT_RESERVED && pw->pw_uid != 0)) { | |
878 | success = 0; | |
879 | packet_send_debug("Server has disabled port forwarding."); | |
880 | } else { | |
881 | /* Start listening on the port */ | |
882 | success = channel_request_forwarding( | |
883 | listen_address, listen_port, | |
884 | /*unspec host_to_connect*/ "<unspec host>", | |
885 | /*unspec port_to_connect*/ 0, | |
886 | options.gateway_ports, /*remote*/ 1); | |
887 | } | |
888 | xfree(listen_address); | |
889 | } | |
890 | if (want_reply) { | |
891 | packet_start(success ? | |
892 | SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); | |
893 | packet_send(); | |
894 | packet_write_wait(); | |
895 | } | |
896 | xfree(rtype); | |
897 | } | |
898 | ||
899 | void | |
900 | server_init_dispatch_20(void) | |
901 | { | |
902 | debug("server_init_dispatch_20"); | |
903 | dispatch_init(&dispatch_protocol_error); | |
904 | dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); | |
905 | dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); | |
906 | dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); | |
907 | dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); | |
908 | dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); | |
909 | dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); | |
910 | dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); | |
911 | dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &channel_input_channel_request); | |
912 | dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); | |
913 | dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); | |
914 | } | |
915 | void | |
916 | server_init_dispatch_13(void) | |
917 | { | |
918 | debug("server_init_dispatch_13"); | |
919 | dispatch_init(NULL); | |
920 | dispatch_set(SSH_CMSG_EOF, &server_input_eof); | |
921 | dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); | |
922 | dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); | |
923 | dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); | |
924 | dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); | |
925 | dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); | |
926 | dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); | |
927 | dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); | |
928 | dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); | |
929 | } | |
930 | void | |
931 | server_init_dispatch_15(void) | |
932 | { | |
933 | server_init_dispatch_13(); | |
934 | debug("server_init_dispatch_15"); | |
935 | dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); | |
936 | dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); | |
937 | } | |
938 | void | |
939 | server_init_dispatch(void) | |
940 | { | |
941 | if (compat20) | |
942 | server_init_dispatch_20(); | |
943 | else if (compat13) | |
944 | server_init_dispatch_13(); | |
945 | else | |
946 | server_init_dispatch_15(); | |
947 | } |