Mercurial > hg > truffle
annotate src/os/bsd/vm/attachListener_bsd.cpp @ 12951:b3a4d4279fa3
Merge
author | ccheung |
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date | Thu, 24 Oct 2013 17:20:39 -0400 |
parents | 195ff07bc7f6 |
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rev | line source |
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3960 | 1 /* |
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2 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved. |
3960 | 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
4 * | |
5 * This code is free software; you can redistribute it and/or modify it | |
6 * under the terms of the GNU General Public License version 2 only, as | |
7 * published by the Free Software Foundation. | |
8 * | |
9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
12 * version 2 for more details (a copy is included in the LICENSE file that | |
13 * accompanied this code). | |
14 * | |
15 * You should have received a copy of the GNU General Public License version | |
16 * 2 along with this work; if not, write to the Free Software Foundation, | |
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
18 * | |
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
20 * or visit www.oracle.com if you need additional information or have any | |
21 * questions. | |
22 * | |
23 */ | |
24 | |
25 #include "precompiled.hpp" | |
26 #include "runtime/interfaceSupport.hpp" | |
27 #include "runtime/os.hpp" | |
28 #include "services/attachListener.hpp" | |
29 #include "services/dtraceAttacher.hpp" | |
30 | |
31 #include <unistd.h> | |
32 #include <signal.h> | |
33 #include <sys/types.h> | |
34 #include <sys/socket.h> | |
35 #include <sys/un.h> | |
36 #include <sys/stat.h> | |
37 | |
38 #ifndef UNIX_PATH_MAX | |
39 #define UNIX_PATH_MAX sizeof(((struct sockaddr_un *)0)->sun_path) | |
40 #endif | |
41 | |
42 // The attach mechanism on Bsd uses a UNIX domain socket. An attach listener | |
43 // thread is created at startup or is created on-demand via a signal from | |
44 // the client tool. The attach listener creates a socket and binds it to a file | |
45 // in the filesystem. The attach listener then acts as a simple (single- | |
46 // threaded) server - it waits for a client to connect, reads the request, | |
47 // executes it, and returns the response to the client via the socket | |
48 // connection. | |
49 // | |
50 // As the socket is a UNIX domain socket it means that only clients on the | |
51 // local machine can connect. In addition there are two other aspects to | |
52 // the security: | |
53 // 1. The well known file that the socket is bound to has permission 400 | |
54 // 2. When a client connect, the SO_PEERCRED socket option is used to | |
55 // obtain the credentials of client. We check that the effective uid | |
56 // of the client matches this process. | |
57 | |
58 // forward reference | |
59 class BsdAttachOperation; | |
60 | |
61 class BsdAttachListener: AllStatic { | |
62 private: | |
63 // the path to which we bind the UNIX domain socket | |
64 static char _path[UNIX_PATH_MAX]; | |
65 static bool _has_path; | |
66 | |
67 // the file descriptor for the listening socket | |
68 static int _listener; | |
69 | |
70 static void set_path(char* path) { | |
71 if (path == NULL) { | |
72 _has_path = false; | |
73 } else { | |
74 strncpy(_path, path, UNIX_PATH_MAX); | |
75 _path[UNIX_PATH_MAX-1] = '\0'; | |
76 _has_path = true; | |
77 } | |
78 } | |
79 | |
80 static void set_listener(int s) { _listener = s; } | |
81 | |
82 // reads a request from the given connected socket | |
83 static BsdAttachOperation* read_request(int s); | |
84 | |
85 public: | |
86 enum { | |
87 ATTACH_PROTOCOL_VER = 1 // protocol version | |
88 }; | |
89 enum { | |
90 ATTACH_ERROR_BADVERSION = 101 // error codes | |
91 }; | |
92 | |
93 // initialize the listener, returns 0 if okay | |
94 static int init(); | |
95 | |
96 static char* path() { return _path; } | |
97 static bool has_path() { return _has_path; } | |
98 static int listener() { return _listener; } | |
99 | |
100 // write the given buffer to a socket | |
101 static int write_fully(int s, char* buf, int len); | |
102 | |
103 static BsdAttachOperation* dequeue(); | |
104 }; | |
105 | |
106 class BsdAttachOperation: public AttachOperation { | |
107 private: | |
108 // the connection to the client | |
109 int _socket; | |
110 | |
111 public: | |
112 void complete(jint res, bufferedStream* st); | |
113 | |
114 void set_socket(int s) { _socket = s; } | |
115 int socket() const { return _socket; } | |
116 | |
117 BsdAttachOperation(char* name) : AttachOperation(name) { | |
118 set_socket(-1); | |
119 } | |
120 }; | |
121 | |
122 // statics | |
123 char BsdAttachListener::_path[UNIX_PATH_MAX]; | |
124 bool BsdAttachListener::_has_path; | |
125 int BsdAttachListener::_listener = -1; | |
126 | |
127 // Supporting class to help split a buffer into individual components | |
128 class ArgumentIterator : public StackObj { | |
129 private: | |
130 char* _pos; | |
131 char* _end; | |
132 public: | |
133 ArgumentIterator(char* arg_buffer, size_t arg_size) { | |
134 _pos = arg_buffer; | |
135 _end = _pos + arg_size - 1; | |
136 } | |
137 char* next() { | |
138 if (*_pos == '\0') { | |
139 return NULL; | |
140 } | |
141 char* res = _pos; | |
142 char* next_pos = strchr(_pos, '\0'); | |
143 if (next_pos < _end) { | |
144 next_pos++; | |
145 } | |
146 _pos = next_pos; | |
147 return res; | |
148 } | |
149 }; | |
150 | |
151 | |
152 // atexit hook to stop listener and unlink the file that it is | |
153 // bound too. | |
154 extern "C" { | |
155 static void listener_cleanup() { | |
156 static int cleanup_done; | |
157 if (!cleanup_done) { | |
158 cleanup_done = 1; | |
159 int s = BsdAttachListener::listener(); | |
160 if (s != -1) { | |
161 ::close(s); | |
162 } | |
163 if (BsdAttachListener::has_path()) { | |
164 ::unlink(BsdAttachListener::path()); | |
165 } | |
166 } | |
167 } | |
168 } | |
169 | |
170 // Initialization - create a listener socket and bind it to a file | |
171 | |
172 int BsdAttachListener::init() { | |
173 char path[UNIX_PATH_MAX]; // socket file | |
174 char initial_path[UNIX_PATH_MAX]; // socket file during setup | |
175 int listener; // listener socket (file descriptor) | |
176 | |
177 // register function to cleanup | |
178 ::atexit(listener_cleanup); | |
179 | |
180 int n = snprintf(path, UNIX_PATH_MAX, "%s/.java_pid%d", | |
181 os::get_temp_directory(), os::current_process_id()); | |
182 if (n < (int)UNIX_PATH_MAX) { | |
183 n = snprintf(initial_path, UNIX_PATH_MAX, "%s.tmp", path); | |
184 } | |
185 if (n >= (int)UNIX_PATH_MAX) { | |
186 return -1; | |
187 } | |
188 | |
189 // create the listener socket | |
190 listener = ::socket(PF_UNIX, SOCK_STREAM, 0); | |
191 if (listener == -1) { | |
192 return -1; | |
193 } | |
194 | |
195 // bind socket | |
196 struct sockaddr_un addr; | |
197 addr.sun_family = AF_UNIX; | |
198 strcpy(addr.sun_path, initial_path); | |
199 ::unlink(initial_path); | |
200 int res = ::bind(listener, (struct sockaddr*)&addr, sizeof(addr)); | |
201 if (res == -1) { | |
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202 ::close(listener); |
3960 | 203 return -1; |
204 } | |
205 | |
206 // put in listen mode, set permissions, and rename into place | |
207 res = ::listen(listener, 5); | |
208 if (res == 0) { | |
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209 RESTARTABLE(::chmod(initial_path, S_IREAD|S_IWRITE), res); |
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210 if (res == 0) { |
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211 // make sure the file is owned by the effective user and effective group |
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212 // (this is the default on linux, but not on mac os) |
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213 RESTARTABLE(::chown(initial_path, geteuid(), getegid()), res); |
3960 | 214 if (res == 0) { |
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215 res = ::rename(initial_path, path); |
3960 | 216 } |
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217 } |
3960 | 218 } |
219 if (res == -1) { | |
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220 ::close(listener); |
3960 | 221 ::unlink(initial_path); |
222 return -1; | |
223 } | |
224 set_path(path); | |
225 set_listener(listener); | |
226 | |
227 return 0; | |
228 } | |
229 | |
230 // Given a socket that is connected to a peer we read the request and | |
231 // create an AttachOperation. As the socket is blocking there is potential | |
232 // for a denial-of-service if the peer does not response. However this happens | |
233 // after the peer credentials have been checked and in the worst case it just | |
234 // means that the attach listener thread is blocked. | |
235 // | |
236 BsdAttachOperation* BsdAttachListener::read_request(int s) { | |
237 char ver_str[8]; | |
238 sprintf(ver_str, "%d", ATTACH_PROTOCOL_VER); | |
239 | |
240 // The request is a sequence of strings so we first figure out the | |
241 // expected count and the maximum possible length of the request. | |
242 // The request is: | |
243 // <ver>0<cmd>0<arg>0<arg>0<arg>0 | |
244 // where <ver> is the protocol version (1), <cmd> is the command | |
245 // name ("load", "datadump", ...), and <arg> is an argument | |
246 int expected_str_count = 2 + AttachOperation::arg_count_max; | |
247 const int max_len = (sizeof(ver_str) + 1) + (AttachOperation::name_length_max + 1) + | |
248 AttachOperation::arg_count_max*(AttachOperation::arg_length_max + 1); | |
249 | |
250 char buf[max_len]; | |
251 int str_count = 0; | |
252 | |
253 // Read until all (expected) strings have been read, the buffer is | |
254 // full, or EOF. | |
255 | |
256 int off = 0; | |
257 int left = max_len; | |
258 | |
259 do { | |
260 int n; | |
261 RESTARTABLE(read(s, buf+off, left), n); | |
262 if (n == -1) { | |
263 return NULL; // reset by peer or other error | |
264 } | |
265 if (n == 0) { | |
266 break; | |
267 } | |
268 for (int i=0; i<n; i++) { | |
269 if (buf[off+i] == 0) { | |
270 // EOS found | |
271 str_count++; | |
272 | |
273 // The first string is <ver> so check it now to | |
274 // check for protocol mis-match | |
275 if (str_count == 1) { | |
276 if ((strlen(buf) != strlen(ver_str)) || | |
277 (atoi(buf) != ATTACH_PROTOCOL_VER)) { | |
278 char msg[32]; | |
279 sprintf(msg, "%d\n", ATTACH_ERROR_BADVERSION); | |
280 write_fully(s, msg, strlen(msg)); | |
281 return NULL; | |
282 } | |
283 } | |
284 } | |
285 } | |
286 off += n; | |
287 left -= n; | |
288 } while (left > 0 && str_count < expected_str_count); | |
289 | |
290 if (str_count != expected_str_count) { | |
291 return NULL; // incomplete request | |
292 } | |
293 | |
294 // parse request | |
295 | |
296 ArgumentIterator args(buf, (max_len)-left); | |
297 | |
298 // version already checked | |
299 char* v = args.next(); | |
300 | |
301 char* name = args.next(); | |
302 if (name == NULL || strlen(name) > AttachOperation::name_length_max) { | |
303 return NULL; | |
304 } | |
305 | |
306 BsdAttachOperation* op = new BsdAttachOperation(name); | |
307 | |
308 for (int i=0; i<AttachOperation::arg_count_max; i++) { | |
309 char* arg = args.next(); | |
310 if (arg == NULL) { | |
311 op->set_arg(i, NULL); | |
312 } else { | |
313 if (strlen(arg) > AttachOperation::arg_length_max) { | |
314 delete op; | |
315 return NULL; | |
316 } | |
317 op->set_arg(i, arg); | |
318 } | |
319 } | |
320 | |
321 op->set_socket(s); | |
322 return op; | |
323 } | |
324 | |
325 | |
326 // Dequeue an operation | |
327 // | |
328 // In the Bsd implementation there is only a single operation and clients | |
329 // cannot queue commands (except at the socket level). | |
330 // | |
331 BsdAttachOperation* BsdAttachListener::dequeue() { | |
332 for (;;) { | |
333 int s; | |
334 | |
335 // wait for client to connect | |
336 struct sockaddr addr; | |
337 socklen_t len = sizeof(addr); | |
338 RESTARTABLE(::accept(listener(), &addr, &len), s); | |
339 if (s == -1) { | |
340 return NULL; // log a warning? | |
341 } | |
342 | |
343 // get the credentials of the peer and check the effective uid/guid | |
344 // - check with jeff on this. | |
345 uid_t puid; | |
346 gid_t pgid; | |
347 if (::getpeereid(s, &puid, &pgid) != 0) { | |
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348 ::close(s); |
3960 | 349 continue; |
350 } | |
351 uid_t euid = geteuid(); | |
352 gid_t egid = getegid(); | |
353 | |
354 if (puid != euid || pgid != egid) { | |
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355 ::close(s); |
3960 | 356 continue; |
357 } | |
358 | |
359 // peer credential look okay so we read the request | |
360 BsdAttachOperation* op = read_request(s); | |
361 if (op == NULL) { | |
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362 ::close(s); |
3960 | 363 continue; |
364 } else { | |
365 return op; | |
366 } | |
367 } | |
368 } | |
369 | |
370 // write the given buffer to the socket | |
371 int BsdAttachListener::write_fully(int s, char* buf, int len) { | |
372 do { | |
373 int n = ::write(s, buf, len); | |
374 if (n == -1) { | |
375 if (errno != EINTR) return -1; | |
376 } else { | |
377 buf += n; | |
378 len -= n; | |
379 } | |
380 } | |
381 while (len > 0); | |
382 return 0; | |
383 } | |
384 | |
385 // Complete an operation by sending the operation result and any result | |
386 // output to the client. At this time the socket is in blocking mode so | |
387 // potentially we can block if there is a lot of data and the client is | |
388 // non-responsive. For most operations this is a non-issue because the | |
389 // default send buffer is sufficient to buffer everything. In the future | |
390 // if there are operations that involves a very big reply then it the | |
391 // socket could be made non-blocking and a timeout could be used. | |
392 | |
393 void BsdAttachOperation::complete(jint result, bufferedStream* st) { | |
394 JavaThread* thread = JavaThread::current(); | |
395 ThreadBlockInVM tbivm(thread); | |
396 | |
397 thread->set_suspend_equivalent(); | |
398 // cleared by handle_special_suspend_equivalent_condition() or | |
399 // java_suspend_self() via check_and_wait_while_suspended() | |
400 | |
401 // write operation result | |
402 char msg[32]; | |
403 sprintf(msg, "%d\n", result); | |
404 int rc = BsdAttachListener::write_fully(this->socket(), msg, strlen(msg)); | |
405 | |
406 // write any result data | |
407 if (rc == 0) { | |
408 BsdAttachListener::write_fully(this->socket(), (char*) st->base(), st->size()); | |
409 ::shutdown(this->socket(), 2); | |
410 } | |
411 | |
412 // done | |
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413 ::close(this->socket()); |
3960 | 414 |
415 // were we externally suspended while we were waiting? | |
416 thread->check_and_wait_while_suspended(); | |
417 | |
418 delete this; | |
419 } | |
420 | |
421 | |
422 // AttachListener functions | |
423 | |
424 AttachOperation* AttachListener::dequeue() { | |
425 JavaThread* thread = JavaThread::current(); | |
426 ThreadBlockInVM tbivm(thread); | |
427 | |
428 thread->set_suspend_equivalent(); | |
429 // cleared by handle_special_suspend_equivalent_condition() or | |
430 // java_suspend_self() via check_and_wait_while_suspended() | |
431 | |
432 AttachOperation* op = BsdAttachListener::dequeue(); | |
433 | |
434 // were we externally suspended while we were waiting? | |
435 thread->check_and_wait_while_suspended(); | |
436 | |
437 return op; | |
438 } | |
439 | |
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440 |
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441 // Performs initialization at vm startup |
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442 // For BSD we remove any stale .java_pid file which could cause |
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443 // an attaching process to think we are ready to receive on the |
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444 // domain socket before we are properly initialized |
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445 |
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446 void AttachListener::vm_start() { |
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447 char fn[UNIX_PATH_MAX]; |
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448 struct stat st; |
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449 int ret; |
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450 |
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451 int n = snprintf(fn, UNIX_PATH_MAX, "%s/.java_pid%d", |
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452 os::get_temp_directory(), os::current_process_id()); |
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453 assert(n < (int)UNIX_PATH_MAX, "java_pid file name buffer overflow"); |
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454 |
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455 RESTARTABLE(::stat(fn, &st), ret); |
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456 if (ret == 0) { |
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457 ret = ::unlink(fn); |
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458 if (ret == -1) { |
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459 debug_only(warning("failed to remove stale attach pid file at %s", fn)); |
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460 } |
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461 } |
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462 } |
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463 |
3960 | 464 int AttachListener::pd_init() { |
465 JavaThread* thread = JavaThread::current(); | |
466 ThreadBlockInVM tbivm(thread); | |
467 | |
468 thread->set_suspend_equivalent(); | |
469 // cleared by handle_special_suspend_equivalent_condition() or | |
470 // java_suspend_self() via check_and_wait_while_suspended() | |
471 | |
472 int ret_code = BsdAttachListener::init(); | |
473 | |
474 // were we externally suspended while we were waiting? | |
475 thread->check_and_wait_while_suspended(); | |
476 | |
477 return ret_code; | |
478 } | |
479 | |
480 // Attach Listener is started lazily except in the case when | |
481 // +ReduseSignalUsage is used | |
482 bool AttachListener::init_at_startup() { | |
483 if (ReduceSignalUsage) { | |
484 return true; | |
485 } else { | |
486 return false; | |
487 } | |
488 } | |
489 | |
490 // If the file .attach_pid<pid> exists in the working directory | |
491 // or /tmp then this is the trigger to start the attach mechanism | |
492 bool AttachListener::is_init_trigger() { | |
493 if (init_at_startup() || is_initialized()) { | |
494 return false; // initialized at startup or already initialized | |
495 } | |
496 char path[PATH_MAX + 1]; | |
497 int ret; | |
498 struct stat st; | |
499 | |
500 snprintf(path, PATH_MAX + 1, "%s/.attach_pid%d", | |
501 os::get_temp_directory(), os::current_process_id()); | |
502 RESTARTABLE(::stat(path, &st), ret); | |
503 if (ret == 0) { | |
504 // simple check to avoid starting the attach mechanism when | |
505 // a bogus user creates the file | |
506 if (st.st_uid == geteuid()) { | |
507 init(); | |
508 return true; | |
509 } | |
510 } | |
511 return false; | |
512 } | |
513 | |
514 // if VM aborts then remove listener | |
515 void AttachListener::abort() { | |
516 listener_cleanup(); | |
517 } | |
518 | |
519 void AttachListener::pd_data_dump() { | |
520 os::signal_notify(SIGQUIT); | |
521 } | |
522 | |
523 AttachOperationFunctionInfo* AttachListener::pd_find_operation(const char* n) { | |
524 return NULL; | |
525 } | |
526 | |
527 jint AttachListener::pd_set_flag(AttachOperation* op, outputStream* out) { | |
528 out->print_cr("flag '%s' cannot be changed", op->arg(0)); | |
529 return JNI_ERR; | |
530 } | |
531 | |
532 void AttachListener::pd_detachall() { | |
533 // do nothing for now | |
534 } |