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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, 2001 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 1.109 2003/06/04 12:03:59 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 "canohost.h" | |
46 | #include "sshpty.h" | |
47 | #include "channels.h" | |
48 | #include "compat.h" | |
49 | #include "ssh1.h" | |
50 | #include "ssh2.h" | |
51 | #include "auth.h" | |
52 | #include "session.h" | |
53 | #include "dispatch.h" | |
54 | #include "auth-options.h" | |
55 | #include "serverloop.h" | |
56 | #include "misc.h" | |
57 | #include "kex.h" | |
58 | ||
59 | extern ServerOptions options; | |
60 | ||
61 | /* XXX */ | |
62 | extern Kex *xxx_kex; | |
63 | static Authctxt *xxx_authctxt; | |
64 | ||
65 | static Buffer stdin_buffer; /* Buffer for stdin data. */ | |
66 | static Buffer stdout_buffer; /* Buffer for stdout data. */ | |
67 | static Buffer stderr_buffer; /* Buffer for stderr data. */ | |
68 | static int fdin; /* Descriptor for stdin (for writing) */ | |
69 | static int fdout; /* Descriptor for stdout (for reading); | |
70 | May be same number as fdin. */ | |
71 | static int fderr; /* Descriptor for stderr. May be -1. */ | |
72 | static long stdin_bytes = 0; /* Number of bytes written to stdin. */ | |
73 | static long stdout_bytes = 0; /* Number of stdout bytes sent to client. */ | |
74 | static long stderr_bytes = 0; /* Number of stderr bytes sent to client. */ | |
75 | static long fdout_bytes = 0; /* Number of stdout bytes read from program. */ | |
76 | static int stdin_eof = 0; /* EOF message received from client. */ | |
77 | static int fdout_eof = 0; /* EOF encountered reading from fdout. */ | |
78 | static int fderr_eof = 0; /* EOF encountered readung from fderr. */ | |
79 | static int fdin_is_tty = 0; /* fdin points to a tty. */ | |
80 | static int connection_in; /* Connection to client (input). */ | |
81 | static int connection_out; /* Connection to client (output). */ | |
82 | static int connection_closed = 0; /* Connection to client closed. */ | |
83 | static u_int buffer_high; /* "Soft" max buffer size. */ | |
84 | static int client_alive_timeouts = 0; | |
85 | ||
86 | /* | |
87 | * This SIGCHLD kludge is used to detect when the child exits. The server | |
88 | * will exit after that, as soon as forwarded connections have terminated. | |
89 | */ | |
90 | ||
91 | static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. */ | |
92 | ||
93 | /* prototypes */ | |
94 | static void server_init_dispatch(void); | |
95 | ||
96 | /* | |
97 | * we write to this pipe if a SIGCHLD is caught in order to avoid | |
98 | * the race between select() and child_terminated | |
99 | */ | |
100 | static int notify_pipe[2]; | |
101 | static void | |
102 | notify_setup(void) | |
103 | { | |
104 | if (pipe(notify_pipe) < 0) { | |
105 | error("pipe(notify_pipe) failed %s", strerror(errno)); | |
106 | } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || | |
107 | (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { | |
108 | error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); | |
109 | close(notify_pipe[0]); | |
110 | close(notify_pipe[1]); | |
111 | } else { | |
112 | set_nonblock(notify_pipe[0]); | |
113 | set_nonblock(notify_pipe[1]); | |
114 | return; | |
115 | } | |
116 | notify_pipe[0] = -1; /* read end */ | |
117 | notify_pipe[1] = -1; /* write end */ | |
118 | } | |
119 | static void | |
120 | notify_parent(void) | |
121 | { | |
122 | if (notify_pipe[1] != -1) | |
123 | write(notify_pipe[1], "", 1); | |
124 | } | |
125 | static void | |
126 | notify_prepare(fd_set *readset) | |
127 | { | |
128 | if (notify_pipe[0] != -1) | |
129 | FD_SET(notify_pipe[0], readset); | |
130 | } | |
131 | static void | |
132 | notify_done(fd_set *readset) | |
133 | { | |
134 | char c; | |
135 | ||
136 | if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) | |
137 | while (read(notify_pipe[0], &c, 1) != -1) | |
138 | debug2("notify_done: reading"); | |
139 | } | |
140 | ||
141 | static void | |
142 | sigchld_handler(int sig) | |
143 | { | |
144 | int save_errno = errno; | |
145 | debug("Received SIGCHLD."); | |
146 | child_terminated = 1; | |
147 | #ifndef _UNICOS | |
148 | mysignal(SIGCHLD, sigchld_handler); | |
149 | #endif | |
150 | notify_parent(); | |
151 | errno = save_errno; | |
152 | } | |
153 | ||
154 | /* | |
155 | * Make packets from buffered stderr data, and buffer it for sending | |
156 | * to the client. | |
157 | */ | |
158 | static void | |
159 | make_packets_from_stderr_data(void) | |
160 | { | |
161 | int len; | |
162 | ||
163 | /* Send buffered stderr data to the client. */ | |
164 | while (buffer_len(&stderr_buffer) > 0 && | |
165 | packet_not_very_much_data_to_write()) { | |
166 | len = buffer_len(&stderr_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_STDERR_DATA); | |
176 | packet_put_string(buffer_ptr(&stderr_buffer), len); | |
177 | packet_send(); | |
178 | buffer_consume(&stderr_buffer, len); | |
179 | stderr_bytes += len; | |
180 | } | |
181 | } | |
182 | ||
183 | /* | |
184 | * Make packets from buffered stdout data, and buffer it for sending to the | |
185 | * client. | |
186 | */ | |
187 | static void | |
188 | make_packets_from_stdout_data(void) | |
189 | { | |
190 | int len; | |
191 | ||
192 | /* Send buffered stdout data to the client. */ | |
193 | while (buffer_len(&stdout_buffer) > 0 && | |
194 | packet_not_very_much_data_to_write()) { | |
195 | len = buffer_len(&stdout_buffer); | |
196 | if (packet_is_interactive()) { | |
197 | if (len > 512) | |
198 | len = 512; | |
199 | } else { | |
200 | /* Keep the packets at reasonable size. */ | |
201 | if (len > packet_get_maxsize()) | |
202 | len = packet_get_maxsize(); | |
203 | } | |
204 | packet_start(SSH_SMSG_STDOUT_DATA); | |
205 | packet_put_string(buffer_ptr(&stdout_buffer), len); | |
206 | packet_send(); | |
207 | buffer_consume(&stdout_buffer, len); | |
208 | stdout_bytes += len; | |
209 | } | |
210 | } | |
211 | ||
212 | static void | |
213 | client_alive_check(void) | |
214 | { | |
215 | static int had_channel = 0; | |
216 | int id; | |
217 | ||
218 | id = channel_find_open(); | |
219 | if (id == -1) { | |
220 | if (!had_channel) | |
221 | return; | |
222 | packet_disconnect("No open channels after timeout!"); | |
223 | } | |
224 | had_channel = 1; | |
225 | ||
226 | /* timeout, check to see how many we have had */ | |
227 | if (++client_alive_timeouts > options.client_alive_count_max) | |
228 | packet_disconnect("Timeout, your session not responding."); | |
229 | ||
230 | /* | |
231 | * send a bogus channel request with "wantreply", | |
232 | * we should get back a failure | |
233 | */ | |
234 | channel_request_start(id, "keepalive@openssh.com", 1); | |
235 | packet_send(); | |
236 | } | |
237 | ||
238 | /* | |
239 | * Sleep in select() until we can do something. This will initialize the | |
240 | * select masks. Upon return, the masks will indicate which descriptors | |
241 | * have data or can accept data. Optionally, a maximum time can be specified | |
242 | * for the duration of the wait (0 = infinite). | |
243 | */ | |
244 | static void | |
245 | wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, | |
246 | int *nallocp, u_int max_time_milliseconds) | |
247 | { | |
248 | struct timeval tv, *tvp; | |
249 | int ret; | |
250 | int client_alive_scheduled = 0; | |
251 | ||
252 | /* | |
253 | * if using client_alive, set the max timeout accordingly, | |
254 | * and indicate that this particular timeout was for client | |
255 | * alive by setting the client_alive_scheduled flag. | |
256 | * | |
257 | * this could be randomized somewhat to make traffic | |
258 | * analysis more difficult, but we're not doing it yet. | |
259 | */ | |
260 | if (compat20 && | |
261 | max_time_milliseconds == 0 && options.client_alive_interval) { | |
262 | client_alive_scheduled = 1; | |
263 | max_time_milliseconds = options.client_alive_interval * 1000; | |
264 | } | |
265 | ||
266 | /* Allocate and update select() masks for channel descriptors. */ | |
267 | channel_prepare_select(readsetp, writesetp, maxfdp, nallocp, 0); | |
268 | ||
269 | if (compat20) { | |
270 | #if 0 | |
271 | /* wrong: bad condition XXX */ | |
272 | if (channel_not_very_much_buffered_data()) | |
273 | #endif | |
274 | FD_SET(connection_in, *readsetp); | |
275 | } else { | |
276 | /* | |
277 | * Read packets from the client unless we have too much | |
278 | * buffered stdin or channel data. | |
279 | */ | |
280 | if (buffer_len(&stdin_buffer) < buffer_high && | |
281 | channel_not_very_much_buffered_data()) | |
282 | FD_SET(connection_in, *readsetp); | |
283 | /* | |
284 | * If there is not too much data already buffered going to | |
285 | * the client, try to get some more data from the program. | |
286 | */ | |
287 | if (packet_not_very_much_data_to_write()) { | |
288 | if (!fdout_eof) | |
289 | FD_SET(fdout, *readsetp); | |
290 | if (!fderr_eof) | |
291 | FD_SET(fderr, *readsetp); | |
292 | } | |
293 | /* | |
294 | * If we have buffered data, try to write some of that data | |
295 | * to the program. | |
296 | */ | |
297 | if (fdin != -1 && buffer_len(&stdin_buffer) > 0) | |
298 | FD_SET(fdin, *writesetp); | |
299 | } | |
300 | notify_prepare(*readsetp); | |
301 | ||
302 | /* | |
303 | * If we have buffered packet data going to the client, mark that | |
304 | * descriptor. | |
305 | */ | |
306 | if (packet_have_data_to_write()) | |
307 | FD_SET(connection_out, *writesetp); | |
308 | ||
309 | /* | |
310 | * If child has terminated and there is enough buffer space to read | |
311 | * from it, then read as much as is available and exit. | |
312 | */ | |
313 | if (child_terminated && packet_not_very_much_data_to_write()) | |
314 | if (max_time_milliseconds == 0 || client_alive_scheduled) | |
315 | max_time_milliseconds = 100; | |
316 | ||
317 | if (max_time_milliseconds == 0) | |
318 | tvp = NULL; | |
319 | else { | |
320 | tv.tv_sec = max_time_milliseconds / 1000; | |
321 | tv.tv_usec = 1000 * (max_time_milliseconds % 1000); | |
322 | tvp = &tv; | |
323 | } | |
324 | ||
325 | /* Wait for something to happen, or the timeout to expire. */ | |
326 | ret = select((*maxfdp)+1, *readsetp, *writesetp, NULL, tvp); | |
327 | ||
328 | if (ret == -1) { | |
329 | memset(*readsetp, 0, *nallocp); | |
330 | memset(*writesetp, 0, *nallocp); | |
331 | if (errno != EINTR) | |
332 | error("select: %.100s", strerror(errno)); | |
333 | } else if (ret == 0 && client_alive_scheduled) | |
334 | client_alive_check(); | |
335 | ||
336 | notify_done(*readsetp); | |
337 | } | |
338 | ||
339 | /* | |
340 | * Processes input from the client and the program. Input data is stored | |
341 | * in buffers and processed later. | |
342 | */ | |
343 | static void | |
344 | process_input(fd_set * readset) | |
345 | { | |
346 | int len; | |
347 | char buf[16384]; | |
348 | ||
349 | /* Read and buffer any input data from the client. */ | |
350 | if (FD_ISSET(connection_in, readset)) { | |
351 | len = read(connection_in, buf, sizeof(buf)); | |
352 | if (len == 0) { | |
353 | verbose("Connection closed by %.100s", | |
354 | get_remote_ipaddr()); | |
355 | connection_closed = 1; | |
356 | if (compat20) | |
357 | return; | |
358 | fatal_cleanup(); | |
359 | } else if (len < 0) { | |
360 | if (errno != EINTR && errno != EAGAIN) { | |
361 | verbose("Read error from remote host " | |
362 | "%.100s: %.100s", | |
363 | get_remote_ipaddr(), strerror(errno)); | |
364 | fatal_cleanup(); | |
365 | } | |
366 | } else { | |
367 | /* Buffer any received data. */ | |
368 | packet_process_incoming(buf, len); | |
369 | } | |
370 | } | |
371 | if (compat20) | |
372 | return; | |
373 | ||
374 | /* Read and buffer any available stdout data from the program. */ | |
375 | if (!fdout_eof && FD_ISSET(fdout, readset)) { | |
376 | len = read(fdout, buf, sizeof(buf)); | |
377 | if (len < 0 && (errno == EINTR || errno == EAGAIN)) { | |
378 | /* do nothing */ | |
379 | } else if (len <= 0) { | |
380 | fdout_eof = 1; | |
381 | } else { | |
382 | buffer_append(&stdout_buffer, buf, len); | |
383 | fdout_bytes += len; | |
384 | } | |
385 | } | |
386 | /* Read and buffer any available stderr data from the program. */ | |
387 | if (!fderr_eof && FD_ISSET(fderr, readset)) { | |
388 | len = read(fderr, buf, sizeof(buf)); | |
389 | if (len < 0 && (errno == EINTR || errno == EAGAIN)) { | |
390 | /* do nothing */ | |
391 | } else if (len <= 0) { | |
392 | fderr_eof = 1; | |
393 | } else { | |
394 | buffer_append(&stderr_buffer, buf, len); | |
395 | } | |
396 | } | |
397 | } | |
398 | ||
399 | /* | |
400 | * Sends data from internal buffers to client program stdin. | |
401 | */ | |
402 | static void | |
403 | process_output(fd_set * writeset) | |
404 | { | |
405 | struct termios tio; | |
406 | u_char *data; | |
407 | u_int dlen; | |
408 | int len; | |
409 | ||
410 | /* Write buffered data to program stdin. */ | |
411 | if (!compat20 && fdin != -1 && FD_ISSET(fdin, writeset)) { | |
412 | data = buffer_ptr(&stdin_buffer); | |
413 | dlen = buffer_len(&stdin_buffer); | |
414 | len = write(fdin, data, dlen); | |
415 | if (len < 0 && (errno == EINTR || errno == EAGAIN)) { | |
416 | /* do nothing */ | |
417 | } else if (len <= 0) { | |
418 | if (fdin != fdout) | |
419 | close(fdin); | |
420 | else | |
421 | shutdown(fdin, SHUT_WR); /* We will no longer send. */ | |
422 | fdin = -1; | |
423 | } else { | |
424 | /* Successful write. */ | |
425 | if (fdin_is_tty && dlen >= 1 && data[0] != '\r' && | |
426 | tcgetattr(fdin, &tio) == 0 && | |
427 | !(tio.c_lflag & ECHO) && (tio.c_lflag & ICANON)) { | |
428 | /* | |
429 | * Simulate echo to reduce the impact of | |
430 | * traffic analysis | |
431 | */ | |
432 | packet_send_ignore(len); | |
433 | packet_send(); | |
434 | } | |
435 | /* Consume the data from the buffer. */ | |
436 | buffer_consume(&stdin_buffer, len); | |
437 | /* Update the count of bytes written to the program. */ | |
438 | stdin_bytes += len; | |
439 | } | |
440 | } | |
441 | /* Send any buffered packet data to the client. */ | |
442 | if (FD_ISSET(connection_out, writeset)) | |
443 | packet_write_poll(); | |
444 | } | |
445 | ||
446 | /* | |
447 | * Wait until all buffered output has been sent to the client. | |
448 | * This is used when the program terminates. | |
449 | */ | |
450 | static void | |
451 | drain_output(void) | |
452 | { | |
453 | /* Send any buffered stdout data to the client. */ | |
454 | if (buffer_len(&stdout_buffer) > 0) { | |
455 | packet_start(SSH_SMSG_STDOUT_DATA); | |
456 | packet_put_string(buffer_ptr(&stdout_buffer), | |
457 | buffer_len(&stdout_buffer)); | |
458 | packet_send(); | |
459 | /* Update the count of sent bytes. */ | |
460 | stdout_bytes += buffer_len(&stdout_buffer); | |
461 | } | |
462 | /* Send any buffered stderr data to the client. */ | |
463 | if (buffer_len(&stderr_buffer) > 0) { | |
464 | packet_start(SSH_SMSG_STDERR_DATA); | |
465 | packet_put_string(buffer_ptr(&stderr_buffer), | |
466 | buffer_len(&stderr_buffer)); | |
467 | packet_send(); | |
468 | /* Update the count of sent bytes. */ | |
469 | stderr_bytes += buffer_len(&stderr_buffer); | |
470 | } | |
471 | /* Wait until all buffered data has been written to the client. */ | |
472 | packet_write_wait(); | |
473 | } | |
474 | ||
475 | static void | |
476 | process_buffered_input_packets(void) | |
477 | { | |
478 | dispatch_run(DISPATCH_NONBLOCK, NULL, compat20 ? xxx_kex : NULL); | |
479 | } | |
480 | ||
481 | /* | |
482 | * Performs the interactive session. This handles data transmission between | |
483 | * the client and the program. Note that the notion of stdin, stdout, and | |
484 | * stderr in this function is sort of reversed: this function writes to | |
485 | * stdin (of the child program), and reads from stdout and stderr (of the | |
486 | * child program). | |
487 | */ | |
488 | void | |
489 | server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) | |
490 | { | |
491 | fd_set *readset = NULL, *writeset = NULL; | |
492 | int max_fd = 0, nalloc = 0; | |
493 | int wait_status; /* Status returned by wait(). */ | |
494 | pid_t wait_pid; /* pid returned by wait(). */ | |
495 | int waiting_termination = 0; /* Have displayed waiting close message. */ | |
496 | u_int max_time_milliseconds; | |
497 | u_int previous_stdout_buffer_bytes; | |
498 | u_int stdout_buffer_bytes; | |
499 | int type; | |
500 | ||
501 | debug("Entering interactive session."); | |
502 | ||
503 | /* Initialize the SIGCHLD kludge. */ | |
504 | child_terminated = 0; | |
505 | mysignal(SIGCHLD, sigchld_handler); | |
506 | ||
507 | /* Initialize our global variables. */ | |
508 | fdin = fdin_arg; | |
509 | fdout = fdout_arg; | |
510 | fderr = fderr_arg; | |
511 | ||
512 | /* nonblocking IO */ | |
513 | set_nonblock(fdin); | |
514 | set_nonblock(fdout); | |
515 | /* we don't have stderr for interactive terminal sessions, see below */ | |
516 | if (fderr != -1) | |
517 | set_nonblock(fderr); | |
518 | ||
519 | if (!(datafellows & SSH_BUG_IGNOREMSG) && isatty(fdin)) | |
520 | fdin_is_tty = 1; | |
521 | ||
522 | connection_in = packet_get_connection_in(); | |
523 | connection_out = packet_get_connection_out(); | |
524 | ||
525 | notify_setup(); | |
526 | ||
527 | previous_stdout_buffer_bytes = 0; | |
528 | ||
529 | /* Set approximate I/O buffer size. */ | |
530 | if (packet_is_interactive()) | |
531 | buffer_high = 4096; | |
532 | else | |
533 | buffer_high = 64 * 1024; | |
534 | ||
535 | #if 0 | |
536 | /* Initialize max_fd to the maximum of the known file descriptors. */ | |
537 | max_fd = MAX(connection_in, connection_out); | |
538 | max_fd = MAX(max_fd, fdin); | |
539 | max_fd = MAX(max_fd, fdout); | |
540 | if (fderr != -1) | |
541 | max_fd = MAX(max_fd, fderr); | |
542 | #endif | |
543 | ||
544 | /* Initialize Initialize buffers. */ | |
545 | buffer_init(&stdin_buffer); | |
546 | buffer_init(&stdout_buffer); | |
547 | buffer_init(&stderr_buffer); | |
548 | ||
549 | /* | |
550 | * If we have no separate fderr (which is the case when we have a pty | |
551 | * - there we cannot make difference between data sent to stdout and | |
552 | * stderr), indicate that we have seen an EOF from stderr. This way | |
553 | * we don\'t need to check the descriptor everywhere. | |
554 | */ | |
555 | if (fderr == -1) | |
556 | fderr_eof = 1; | |
557 | ||
558 | server_init_dispatch(); | |
559 | ||
560 | /* Main loop of the server for the interactive session mode. */ | |
561 | for (;;) { | |
562 | ||
563 | /* Process buffered packets from the client. */ | |
564 | process_buffered_input_packets(); | |
565 | ||
566 | /* | |
567 | * If we have received eof, and there is no more pending | |
568 | * input data, cause a real eof by closing fdin. | |
569 | */ | |
570 | if (stdin_eof && fdin != -1 && buffer_len(&stdin_buffer) == 0) { | |
571 | if (fdin != fdout) | |
572 | close(fdin); | |
573 | else | |
574 | shutdown(fdin, SHUT_WR); /* We will no longer send. */ | |
575 | fdin = -1; | |
576 | } | |
577 | /* Make packets from buffered stderr data to send to the client. */ | |
578 | make_packets_from_stderr_data(); | |
579 | ||
580 | /* | |
581 | * Make packets from buffered stdout data to send to the | |
582 | * client. If there is very little to send, this arranges to | |
583 | * not send them now, but to wait a short while to see if we | |
584 | * are getting more data. This is necessary, as some systems | |
585 | * wake up readers from a pty after each separate character. | |
586 | */ | |
587 | max_time_milliseconds = 0; | |
588 | stdout_buffer_bytes = buffer_len(&stdout_buffer); | |
589 | if (stdout_buffer_bytes != 0 && stdout_buffer_bytes < 256 && | |
590 | stdout_buffer_bytes != previous_stdout_buffer_bytes) { | |
591 | /* try again after a while */ | |
592 | max_time_milliseconds = 10; | |
593 | } else { | |
594 | /* Send it now. */ | |
595 | make_packets_from_stdout_data(); | |
596 | } | |
597 | previous_stdout_buffer_bytes = buffer_len(&stdout_buffer); | |
598 | ||
599 | /* Send channel data to the client. */ | |
600 | if (packet_not_very_much_data_to_write()) | |
601 | channel_output_poll(); | |
602 | ||
603 | /* | |
604 | * Bail out of the loop if the program has closed its output | |
605 | * descriptors, and we have no more data to send to the | |
606 | * client, and there is no pending buffered data. | |
607 | */ | |
608 | if (fdout_eof && fderr_eof && !packet_have_data_to_write() && | |
609 | buffer_len(&stdout_buffer) == 0 && buffer_len(&stderr_buffer) == 0) { | |
610 | if (!channel_still_open()) | |
611 | break; | |
612 | if (!waiting_termination) { | |
613 | const char *s = "Waiting for forwarded connections to terminate...\r\n"; | |
614 | char *cp; | |
615 | waiting_termination = 1; | |
616 | buffer_append(&stderr_buffer, s, strlen(s)); | |
617 | ||
618 | /* Display list of open channels. */ | |
619 | cp = channel_open_message(); | |
620 | buffer_append(&stderr_buffer, cp, strlen(cp)); | |
621 | xfree(cp); | |
622 | } | |
623 | } | |
624 | max_fd = MAX(connection_in, connection_out); | |
625 | max_fd = MAX(max_fd, fdin); | |
626 | max_fd = MAX(max_fd, fdout); | |
627 | max_fd = MAX(max_fd, fderr); | |
628 | max_fd = MAX(max_fd, notify_pipe[0]); | |
629 | ||
630 | /* Sleep in select() until we can do something. */ | |
631 | wait_until_can_do_something(&readset, &writeset, &max_fd, | |
632 | &nalloc, max_time_milliseconds); | |
633 | ||
634 | /* Process any channel events. */ | |
635 | channel_after_select(readset, writeset); | |
636 | ||
637 | /* Process input from the client and from program stdout/stderr. */ | |
638 | process_input(readset); | |
639 | ||
640 | /* Process output to the client and to program stdin. */ | |
641 | process_output(writeset); | |
642 | } | |
643 | if (readset) | |
644 | xfree(readset); | |
645 | if (writeset) | |
646 | xfree(writeset); | |
647 | ||
648 | /* Cleanup and termination code. */ | |
649 | ||
650 | /* Wait until all output has been sent to the client. */ | |
651 | drain_output(); | |
652 | ||
653 | debug("End of interactive session; stdin %ld, stdout (read %ld, sent %ld), stderr %ld bytes.", | |
654 | stdin_bytes, fdout_bytes, stdout_bytes, stderr_bytes); | |
655 | ||
656 | /* Free and clear the buffers. */ | |
657 | buffer_free(&stdin_buffer); | |
658 | buffer_free(&stdout_buffer); | |
659 | buffer_free(&stderr_buffer); | |
660 | ||
661 | /* Close the file descriptors. */ | |
662 | if (fdout != -1) | |
663 | close(fdout); | |
664 | fdout = -1; | |
665 | fdout_eof = 1; | |
666 | if (fderr != -1) | |
667 | close(fderr); | |
668 | fderr = -1; | |
669 | fderr_eof = 1; | |
670 | if (fdin != -1) | |
671 | close(fdin); | |
672 | fdin = -1; | |
673 | ||
674 | channel_free_all(); | |
675 | ||
676 | /* We no longer want our SIGCHLD handler to be called. */ | |
677 | mysignal(SIGCHLD, SIG_DFL); | |
678 | ||
679 | while ((wait_pid = waitpid(-1, &wait_status, 0)) < 0) | |
680 | if (errno != EINTR) | |
681 | packet_disconnect("wait: %.100s", strerror(errno)); | |
682 | if (wait_pid != pid) | |
683 | error("Strange, wait returned pid %ld, expected %ld", | |
684 | (long)wait_pid, (long)pid); | |
685 | ||
686 | /* Check if it exited normally. */ | |
687 | if (WIFEXITED(wait_status)) { | |
688 | /* Yes, normal exit. Get exit status and send it to the client. */ | |
689 | debug("Command exited with status %d.", WEXITSTATUS(wait_status)); | |
690 | packet_start(SSH_SMSG_EXITSTATUS); | |
691 | packet_put_int(WEXITSTATUS(wait_status)); | |
692 | packet_send(); | |
693 | packet_write_wait(); | |
694 | ||
695 | /* | |
696 | * Wait for exit confirmation. Note that there might be | |
697 | * other packets coming before it; however, the program has | |
698 | * already died so we just ignore them. The client is | |
699 | * supposed to respond with the confirmation when it receives | |
700 | * the exit status. | |
701 | */ | |
702 | do { | |
703 | type = packet_read(); | |
704 | } | |
705 | while (type != SSH_CMSG_EXIT_CONFIRMATION); | |
706 | ||
707 | debug("Received exit confirmation."); | |
708 | return; | |
709 | } | |
710 | /* Check if the program terminated due to a signal. */ | |
711 | if (WIFSIGNALED(wait_status)) | |
712 | packet_disconnect("Command terminated on signal %d.", | |
713 | WTERMSIG(wait_status)); | |
714 | ||
715 | /* Some weird exit cause. Just exit. */ | |
716 | packet_disconnect("wait returned status %04x.", wait_status); | |
717 | /* NOTREACHED */ | |
718 | } | |
719 | ||
720 | static void | |
721 | collect_children(void) | |
722 | { | |
723 | pid_t pid; | |
724 | sigset_t oset, nset; | |
725 | int status; | |
726 | ||
727 | /* block SIGCHLD while we check for dead children */ | |
728 | sigemptyset(&nset); | |
729 | sigaddset(&nset, SIGCHLD); | |
730 | sigprocmask(SIG_BLOCK, &nset, &oset); | |
731 | if (child_terminated) { | |
732 | while ((pid = waitpid(-1, &status, WNOHANG)) > 0 || | |
733 | (pid < 0 && errno == EINTR)) | |
734 | if (pid > 0) | |
735 | session_close_by_pid(pid, status); | |
736 | child_terminated = 0; | |
737 | } | |
738 | sigprocmask(SIG_SETMASK, &oset, NULL); | |
739 | } | |
740 | ||
741 | void | |
742 | server_loop2(Authctxt *authctxt) | |
743 | { | |
744 | fd_set *readset = NULL, *writeset = NULL; | |
745 | int rekeying = 0, max_fd, nalloc = 0; | |
746 | ||
747 | debug("Entering interactive session for SSH2."); | |
748 | ||
749 | mysignal(SIGCHLD, sigchld_handler); | |
750 | child_terminated = 0; | |
751 | connection_in = packet_get_connection_in(); | |
752 | connection_out = packet_get_connection_out(); | |
753 | ||
754 | notify_setup(); | |
755 | ||
756 | max_fd = MAX(connection_in, connection_out); | |
757 | max_fd = MAX(max_fd, notify_pipe[0]); | |
758 | ||
759 | xxx_authctxt = authctxt; | |
760 | ||
761 | server_init_dispatch(); | |
762 | ||
763 | for (;;) { | |
764 | process_buffered_input_packets(); | |
765 | ||
766 | rekeying = (xxx_kex != NULL && !xxx_kex->done); | |
767 | ||
768 | if (!rekeying && packet_not_very_much_data_to_write()) | |
769 | channel_output_poll(); | |
770 | wait_until_can_do_something(&readset, &writeset, &max_fd, | |
771 | &nalloc, 0); | |
772 | ||
773 | collect_children(); | |
774 | if (!rekeying) { | |
775 | channel_after_select(readset, writeset); | |
776 | if (packet_need_rekeying()) { | |
777 | debug("need rekeying"); | |
778 | xxx_kex->done = 0; | |
779 | kex_send_kexinit(xxx_kex); | |
780 | } | |
781 | } | |
782 | process_input(readset); | |
783 | if (connection_closed) | |
784 | break; | |
785 | process_output(writeset); | |
786 | } | |
787 | collect_children(); | |
788 | ||
789 | if (readset) | |
790 | xfree(readset); | |
791 | if (writeset) | |
792 | xfree(writeset); | |
793 | ||
794 | /* free all channels, no more reads and writes */ | |
795 | channel_free_all(); | |
796 | ||
797 | /* free remaining sessions, e.g. remove wtmp entries */ | |
798 | session_destroy_all(NULL); | |
799 | } | |
800 | ||
801 | static void | |
802 | server_input_channel_failure(int type, u_int32_t seq, void *ctxt) | |
803 | { | |
804 | debug("Got CHANNEL_FAILURE for keepalive"); | |
805 | /* | |
806 | * reset timeout, since we got a sane answer from the client. | |
807 | * even if this was generated by something other than | |
808 | * the bogus CHANNEL_REQUEST we send for keepalives. | |
809 | */ | |
810 | client_alive_timeouts = 0; | |
811 | } | |
812 | ||
813 | ||
814 | static void | |
815 | server_input_stdin_data(int type, u_int32_t seq, void *ctxt) | |
816 | { | |
817 | char *data; | |
818 | u_int data_len; | |
819 | ||
820 | /* Stdin data from the client. Append it to the buffer. */ | |
821 | /* Ignore any data if the client has closed stdin. */ | |
822 | if (fdin == -1) | |
823 | return; | |
824 | data = packet_get_string(&data_len); | |
825 | packet_check_eom(); | |
826 | buffer_append(&stdin_buffer, data, data_len); | |
827 | memset(data, 0, data_len); | |
828 | xfree(data); | |
829 | } | |
830 | ||
831 | static void | |
832 | server_input_eof(int type, u_int32_t seq, void *ctxt) | |
833 | { | |
834 | /* | |
835 | * Eof from the client. The stdin descriptor to the | |
836 | * program will be closed when all buffered data has | |
837 | * drained. | |
838 | */ | |
839 | debug("EOF received for stdin."); | |
840 | packet_check_eom(); | |
841 | stdin_eof = 1; | |
842 | } | |
843 | ||
844 | static void | |
845 | server_input_window_size(int type, u_int32_t seq, void *ctxt) | |
846 | { | |
847 | int row = packet_get_int(); | |
848 | int col = packet_get_int(); | |
849 | int xpixel = packet_get_int(); | |
850 | int ypixel = packet_get_int(); | |
851 | ||
852 | debug("Window change received."); | |
853 | packet_check_eom(); | |
854 | if (fdin != -1) | |
855 | pty_change_window_size(fdin, row, col, xpixel, ypixel); | |
856 | } | |
857 | ||
858 | static Channel * | |
859 | server_request_direct_tcpip(char *ctype) | |
860 | { | |
861 | Channel *c; | |
862 | int sock; | |
863 | char *target, *originator; | |
864 | int target_port, originator_port; | |
865 | ||
866 | target = packet_get_string(NULL); | |
867 | target_port = packet_get_int(); | |
868 | originator = packet_get_string(NULL); | |
869 | originator_port = packet_get_int(); | |
870 | packet_check_eom(); | |
871 | ||
872 | debug("server_request_direct_tcpip: originator %s port %d, target %s port %d", | |
873 | originator, originator_port, target, target_port); | |
874 | ||
875 | /* XXX check permission */ | |
876 | sock = channel_connect_to(target, target_port); | |
877 | xfree(target); | |
878 | xfree(originator); | |
879 | if (sock < 0) | |
880 | return NULL; | |
881 | c = channel_new(ctype, SSH_CHANNEL_CONNECTING, | |
882 | sock, sock, -1, CHAN_TCP_WINDOW_DEFAULT, | |
883 | CHAN_TCP_PACKET_DEFAULT, 0, "direct-tcpip", 1); | |
884 | return c; | |
885 | } | |
886 | ||
887 | static Channel * | |
888 | server_request_session(char *ctype) | |
889 | { | |
890 | Channel *c; | |
891 | ||
892 | debug("input_session_request"); | |
893 | packet_check_eom(); | |
894 | /* | |
895 | * A server session has no fd to read or write until a | |
896 | * CHANNEL_REQUEST for a shell is made, so we set the type to | |
897 | * SSH_CHANNEL_LARVAL. Additionally, a callback for handling all | |
898 | * CHANNEL_REQUEST messages is registered. | |
899 | */ | |
900 | c = channel_new(ctype, SSH_CHANNEL_LARVAL, | |
901 | -1, -1, -1, /*window size*/0, CHAN_SES_PACKET_DEFAULT, | |
902 | 0, "server-session", 1); | |
903 | if (session_open(xxx_authctxt, c->self) != 1) { | |
904 | debug("session open failed, free channel %d", c->self); | |
905 | channel_free(c); | |
906 | return NULL; | |
907 | } | |
908 | channel_register_cleanup(c->self, session_close_by_channel); | |
909 | return c; | |
910 | } | |
911 | ||
912 | static void | |
913 | server_input_channel_open(int type, u_int32_t seq, void *ctxt) | |
914 | { | |
915 | Channel *c = NULL; | |
916 | char *ctype; | |
917 | int rchan; | |
918 | u_int rmaxpack, rwindow, len; | |
919 | ||
920 | ctype = packet_get_string(&len); | |
921 | rchan = packet_get_int(); | |
922 | rwindow = packet_get_int(); | |
923 | rmaxpack = packet_get_int(); | |
924 | ||
925 | debug("server_input_channel_open: ctype %s rchan %d win %d max %d", | |
926 | ctype, rchan, rwindow, rmaxpack); | |
927 | ||
928 | if (strcmp(ctype, "session") == 0) { | |
929 | c = server_request_session(ctype); | |
930 | } else if (strcmp(ctype, "direct-tcpip") == 0) { | |
931 | c = server_request_direct_tcpip(ctype); | |
932 | } | |
933 | if (c != NULL) { | |
934 | debug("server_input_channel_open: confirm %s", ctype); | |
935 | c->remote_id = rchan; | |
936 | c->remote_window = rwindow; | |
937 | c->remote_maxpacket = rmaxpack; | |
938 | if (c->type != SSH_CHANNEL_CONNECTING) { | |
939 | packet_start(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION); | |
940 | packet_put_int(c->remote_id); | |
941 | packet_put_int(c->self); | |
942 | packet_put_int(c->local_window); | |
943 | packet_put_int(c->local_maxpacket); | |
944 | packet_send(); | |
945 | } | |
946 | } else { | |
947 | debug("server_input_channel_open: failure %s", ctype); | |
948 | packet_start(SSH2_MSG_CHANNEL_OPEN_FAILURE); | |
949 | packet_put_int(rchan); | |
950 | packet_put_int(SSH2_OPEN_ADMINISTRATIVELY_PROHIBITED); | |
951 | if (!(datafellows & SSH_BUG_OPENFAILURE)) { | |
952 | packet_put_cstring("open failed"); | |
953 | packet_put_cstring(""); | |
954 | } | |
955 | packet_send(); | |
956 | } | |
957 | xfree(ctype); | |
958 | } | |
959 | ||
960 | static void | |
961 | server_input_global_request(int type, u_int32_t seq, void *ctxt) | |
962 | { | |
963 | char *rtype; | |
964 | int want_reply; | |
965 | int success = 0; | |
966 | ||
967 | rtype = packet_get_string(NULL); | |
968 | want_reply = packet_get_char(); | |
969 | debug("server_input_global_request: rtype %s want_reply %d", rtype, want_reply); | |
970 | ||
971 | /* -R style forwarding */ | |
972 | if (strcmp(rtype, "tcpip-forward") == 0) { | |
973 | struct passwd *pw; | |
974 | char *listen_address; | |
975 | u_short listen_port; | |
976 | ||
977 | pw = auth_get_user(); | |
978 | if (pw == NULL) | |
979 | fatal("server_input_global_request: no user"); | |
980 | listen_address = packet_get_string(NULL); | |
981 | listen_port = (u_short)packet_get_int(); | |
982 | debug("server_input_global_request: tcpip-forward listen %s port %d", | |
983 | listen_address, listen_port); | |
984 | ||
985 | /* check permissions */ | |
986 | if (!options.allow_tcp_forwarding || | |
987 | no_port_forwarding_flag | |
988 | #ifndef NO_IPPORT_RESERVED_CONCEPT | |
989 | || (listen_port < IPPORT_RESERVED && pw->pw_uid != 0) | |
990 | #endif | |
991 | ) { | |
992 | success = 0; | |
993 | packet_send_debug("Server has disabled port forwarding."); | |
994 | } else { | |
995 | /* Start listening on the port */ | |
996 | success = channel_setup_remote_fwd_listener( | |
997 | listen_address, listen_port, options.gateway_ports); | |
998 | } | |
999 | xfree(listen_address); | |
1000 | } | |
1001 | if (want_reply) { | |
1002 | packet_start(success ? | |
1003 | SSH2_MSG_REQUEST_SUCCESS : SSH2_MSG_REQUEST_FAILURE); | |
1004 | packet_send(); | |
1005 | packet_write_wait(); | |
1006 | } | |
1007 | xfree(rtype); | |
1008 | } | |
1009 | static void | |
1010 | server_input_channel_req(int type, u_int32_t seq, void *ctxt) | |
1011 | { | |
1012 | Channel *c; | |
1013 | int id, reply, success = 0; | |
1014 | char *rtype; | |
1015 | ||
1016 | id = packet_get_int(); | |
1017 | rtype = packet_get_string(NULL); | |
1018 | reply = packet_get_char(); | |
1019 | ||
1020 | debug("server_input_channel_req: channel %d request %s reply %d", | |
1021 | id, rtype, reply); | |
1022 | ||
1023 | if ((c = channel_lookup(id)) == NULL) | |
1024 | packet_disconnect("server_input_channel_req: " | |
1025 | "unknown channel %d", id); | |
1026 | if (c->type == SSH_CHANNEL_LARVAL || c->type == SSH_CHANNEL_OPEN) | |
1027 | success = session_input_channel_req(c, rtype); | |
1028 | if (reply) { | |
1029 | packet_start(success ? | |
1030 | SSH2_MSG_CHANNEL_SUCCESS : SSH2_MSG_CHANNEL_FAILURE); | |
1031 | packet_put_int(c->remote_id); | |
1032 | packet_send(); | |
1033 | } | |
1034 | xfree(rtype); | |
1035 | } | |
1036 | ||
1037 | static void | |
1038 | server_init_dispatch_20(void) | |
1039 | { | |
1040 | debug("server_init_dispatch_20"); | |
1041 | dispatch_init(&dispatch_protocol_error); | |
1042 | dispatch_set(SSH2_MSG_CHANNEL_CLOSE, &channel_input_oclose); | |
1043 | dispatch_set(SSH2_MSG_CHANNEL_DATA, &channel_input_data); | |
1044 | dispatch_set(SSH2_MSG_CHANNEL_EOF, &channel_input_ieof); | |
1045 | dispatch_set(SSH2_MSG_CHANNEL_EXTENDED_DATA, &channel_input_extended_data); | |
1046 | dispatch_set(SSH2_MSG_CHANNEL_OPEN, &server_input_channel_open); | |
1047 | dispatch_set(SSH2_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); | |
1048 | dispatch_set(SSH2_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); | |
1049 | dispatch_set(SSH2_MSG_CHANNEL_REQUEST, &server_input_channel_req); | |
1050 | dispatch_set(SSH2_MSG_CHANNEL_WINDOW_ADJUST, &channel_input_window_adjust); | |
1051 | dispatch_set(SSH2_MSG_GLOBAL_REQUEST, &server_input_global_request); | |
1052 | /* client_alive */ | |
1053 | dispatch_set(SSH2_MSG_CHANNEL_FAILURE, &server_input_channel_failure); | |
1054 | /* rekeying */ | |
1055 | dispatch_set(SSH2_MSG_KEXINIT, &kex_input_kexinit); | |
1056 | } | |
1057 | static void | |
1058 | server_init_dispatch_13(void) | |
1059 | { | |
1060 | debug("server_init_dispatch_13"); | |
1061 | dispatch_init(NULL); | |
1062 | dispatch_set(SSH_CMSG_EOF, &server_input_eof); | |
1063 | dispatch_set(SSH_CMSG_STDIN_DATA, &server_input_stdin_data); | |
1064 | dispatch_set(SSH_CMSG_WINDOW_SIZE, &server_input_window_size); | |
1065 | dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_close); | |
1066 | dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_close_confirmation); | |
1067 | dispatch_set(SSH_MSG_CHANNEL_DATA, &channel_input_data); | |
1068 | dispatch_set(SSH_MSG_CHANNEL_OPEN_CONFIRMATION, &channel_input_open_confirmation); | |
1069 | dispatch_set(SSH_MSG_CHANNEL_OPEN_FAILURE, &channel_input_open_failure); | |
1070 | dispatch_set(SSH_MSG_PORT_OPEN, &channel_input_port_open); | |
1071 | } | |
1072 | static void | |
1073 | server_init_dispatch_15(void) | |
1074 | { | |
1075 | server_init_dispatch_13(); | |
1076 | debug("server_init_dispatch_15"); | |
1077 | dispatch_set(SSH_MSG_CHANNEL_CLOSE, &channel_input_ieof); | |
1078 | dispatch_set(SSH_MSG_CHANNEL_CLOSE_CONFIRMATION, &channel_input_oclose); | |
1079 | } | |
1080 | static void | |
1081 | server_init_dispatch(void) | |
1082 | { | |
1083 | if (compat20) | |
1084 | server_init_dispatch_20(); | |
1085 | else if (compat13) | |
1086 | server_init_dispatch_13(); | |
1087 | else | |
1088 | server_init_dispatch_15(); | |
1089 | } |