1 /*
2 * Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved.
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 "incls/_precompiled.incl"
26 # include "incls/_attachListener_solaris.cpp.incl"
27
28 #include <door.h>
29 #include <string.h>
30 #include <signal.h>
31 #include <sys/types.h>
32 #include <sys/socket.h>
33 #include <sys/stat.h>
34
35 // stropts.h uses STR in stream ioctl defines
36 #undef STR
37 #include <stropts.h>
38 #undef STR
39 #define STR(a) #a
40
41 // The attach mechanism on Solaris is implemented using the Doors IPC
42 // mechanism. The first tool to attempt to attach causes the attach
43 // listener thread to startup. This thread creats a door that is
44 // associated with a function that enqueues an operation to the attach
45 // listener. The door is attached to a file in the file system so that
46 // client (tools) can locate it. To enqueue an operation to the VM the
47 // client calls through the door which invokes the enqueue function in
48 // this process. The credentials of the client are checked and if the
49 // effective uid matches this process then the operation is enqueued.
50 // When an operation completes the attach listener is required to send the
51 // operation result and any result data to the client. In this implementation
52 // the result is returned via a UNIX domain socket. A pair of connected
53 // sockets (socketpair) is created in the enqueue function and the file
54 // descriptor for one of the sockets is returned to the client as the
55 // return from the door call. The other end is retained in this process.
56 // When the operation completes the result is sent to the client and
57 // the socket is closed.
58
59 // forward reference
60 class SolarisAttachOperation;
61
62 class SolarisAttachListener: AllStatic {
63 private:
64
65 // the path to which we attach the door file descriptor
66 static char _door_path[PATH_MAX+1];
67 static volatile bool _has_door_path;
68
69 // door descriptor returned by door_create
70 static int _door_descriptor;
71
72 static void set_door_path(char* path) {
73 if (path == NULL) {
74 _has_door_path = false;
75 } else {
76 strncpy(_door_path, path, PATH_MAX);
77 _door_path[PATH_MAX] = '\0'; // ensure it's nul terminated
78 _has_door_path = true;
79 }
80 }
81
82 static void set_door_descriptor(int dd) { _door_descriptor = dd; }
83
84 // mutex to protect operation list
85 static mutex_t _mutex;
86
87 // semaphore to wakeup listener thread
88 static sema_t _wakeup;
89
90 static mutex_t* mutex() { return &_mutex; }
91 static sema_t* wakeup() { return &_wakeup; }
92
93 // enqueued operation list
94 static SolarisAttachOperation* _head;
95 static SolarisAttachOperation* _tail;
96
97 static SolarisAttachOperation* head() { return _head; }
98 static void set_head(SolarisAttachOperation* head) { _head = head; }
99
100 static SolarisAttachOperation* tail() { return _tail; }
101 static void set_tail(SolarisAttachOperation* tail) { _tail = tail; }
102
103 // create the door
104 static int create_door();
105
106 public:
107 enum {
108 ATTACH_PROTOCOL_VER = 1 // protocol version
109 };
110 enum {
111 ATTACH_ERROR_BADREQUEST = 100, // error code returned by
112 ATTACH_ERROR_BADVERSION = 101, // the door call
113 ATTACH_ERROR_RESOURCE = 102,
114 ATTACH_ERROR_INTERNAL = 103,
115 ATTACH_ERROR_DENIED = 104
116 };
117
118 // initialize the listener
119 static int init();
120
121 static bool has_door_path() { return _has_door_path; }
122 static char* door_path() { return _door_path; }
123 static int door_descriptor() { return _door_descriptor; }
124
125 // enqueue an operation
126 static void enqueue(SolarisAttachOperation* op);
127
128 // dequeue an operation
129 static SolarisAttachOperation* dequeue();
130 };
131
132
133 // SolarisAttachOperation is an AttachOperation that additionally encapsulates
134 // a socket connection to the requesting client/tool. SolarisAttachOperation
135 // can additionally be held in a linked list.
136
137 class SolarisAttachOperation: public AttachOperation {
138 private:
139 friend class SolarisAttachListener;
140
141 // connection to client
142 int _socket;
143
144 // linked list support
145 SolarisAttachOperation* _next;
146
147 SolarisAttachOperation* next() { return _next; }
148 void set_next(SolarisAttachOperation* next) { _next = next; }
149
150 public:
151 void complete(jint res, bufferedStream* st);
152
153 int socket() const { return _socket; }
154 void set_socket(int s) { _socket = s; }
155
156 SolarisAttachOperation(char* name) : AttachOperation(name) {
157 set_socket(-1);
158 set_next(NULL);
159 }
160 };
161
162 // statics
163 char SolarisAttachListener::_door_path[PATH_MAX+1];
164 volatile bool SolarisAttachListener::_has_door_path;
165 int SolarisAttachListener::_door_descriptor = -1;
166 mutex_t SolarisAttachListener::_mutex;
167 sema_t SolarisAttachListener::_wakeup;
168 SolarisAttachOperation* SolarisAttachListener::_head = NULL;
169 SolarisAttachOperation* SolarisAttachListener::_tail = NULL;
170
171 // Supporting class to help split a buffer into individual components
172 class ArgumentIterator : public StackObj {
173 private:
174 char* _pos;
175 char* _end;
176 public:
177 ArgumentIterator(char* arg_buffer, size_t arg_size) {
178 _pos = arg_buffer;
179 _end = _pos + arg_size - 1;
180 }
181 char* next() {
182 if (*_pos == '\0') {
183 return NULL;
184 }
185 char* res = _pos;
186 char* next_pos = strchr(_pos, '\0');
187 if (next_pos < _end) {
188 next_pos++;
189 }
190 _pos = next_pos;
191 return res;
192 }
193 };
194
195 // Calls from the door function to check that the client credentials
196 // match this process. Returns 0 if credentials okay, otherwise -1.
197 static int check_credentials() {
198 door_cred_t cred_info;
199
200 // get client credentials
201 if (door_cred(&cred_info) == -1) {
202 return -1; // unable to get them
203 }
204
205 // get our euid/eguid (probably could cache these)
206 uid_t euid = geteuid();
207 gid_t egid = getegid();
208
209 // check that the effective uid/gid matches - discuss this with Jeff.
210 if (cred_info.dc_euid == euid && cred_info.dc_egid == egid) {
211 return 0; // okay
212 } else {
213 return -1; // denied
214 }
215 }
216
217
218 // Parses the argument buffer to create an AttachOperation that we should
219 // enqueue to the attach listener.
220 // The buffer is expected to be formatted as follows:
221 // <ver>0<cmd>0<arg>0<arg>0<arg>0
222 // where <ver> is the version number (must be "1"), <cmd> is the command
223 // name ("load, "datadump", ...) and <arg> is an argument.
224 //
225 static SolarisAttachOperation* create_operation(char* argp, size_t arg_size, int* err) {
226 // assume bad request until parsed
227 *err = SolarisAttachListener::ATTACH_ERROR_BADREQUEST;
228
229 if (arg_size < 2 || argp[arg_size-1] != '\0') {
230 return NULL; // no ver or not null terminated
231 }
232
233 // Use supporting class to iterate over the buffer
234 ArgumentIterator args(argp, arg_size);
235
236 // First check the protocol version
237 char* ver = args.next();
238 if (ver == NULL) {
239 return NULL;
240 }
241 if (atoi(ver) != SolarisAttachListener::ATTACH_PROTOCOL_VER) {
242 *err = SolarisAttachListener::ATTACH_ERROR_BADVERSION;
243 return NULL;
244 }
245
246 // Get command name and create the operation
247 char* name = args.next();
248 if (name == NULL || strlen(name) > AttachOperation::name_length_max) {
249 return NULL;
250 }
251 SolarisAttachOperation* op = new SolarisAttachOperation(name);
252
253 // Iterate over the arguments
254 for (int i=0; i<AttachOperation::arg_count_max; i++) {
255 char* arg = args.next();
256 if (arg == NULL) {
257 op->set_arg(i, NULL);
258 } else {
259 if (strlen(arg) > AttachOperation::arg_length_max) {
260 delete op;
261 return NULL;
262 }
263 op->set_arg(i, arg);
264 }
265 }
266
267 // return operation
268 *err = 0;
269 return op;
270 }
271
272 // create special operation to indicate all clients have detached
273 static SolarisAttachOperation* create_detachall_operation() {
274 return new SolarisAttachOperation(AttachOperation::detachall_operation_name());
275 }
276
277 // This is door function which the client executes via a door_call.
278 extern "C" {
279 static void enqueue_proc(void* cookie, char* argp, size_t arg_size,
280 door_desc_t* dt, uint_t n_desc)
281 {
282 int return_fd = -1;
283 SolarisAttachOperation* op = NULL;
284
285 // no listener
286 jint res = 0;
287 if (!AttachListener::is_initialized()) {
288 // how did we get here?
289 debug_only(warning("door_call when not enabled"));
290 res = (jint)SolarisAttachListener::ATTACH_ERROR_INTERNAL;
291 }
292
293 // check client credentials
294 if (res == 0) {
295 if (check_credentials() != 0) {
296 res = (jint)SolarisAttachListener::ATTACH_ERROR_DENIED;
297 }
298 }
299
300 // if we are stopped at ShowMessageBoxOnError then maybe we can
301 // load a diagnostic library
302 if (res == 0 && is_error_reported()) {
303 if (ShowMessageBoxOnError) {
304 // TBD - support loading of diagnostic library here
305 }
306
307 // can't enqueue operation after fatal error
308 res = (jint)SolarisAttachListener::ATTACH_ERROR_RESOURCE;
309 }
310
311 // create the operation
312 if (res == 0) {
313 int err;
314 op = create_operation(argp, arg_size, &err);
315 res = (op == NULL) ? (jint)err : 0;
316 }
317
318 // create a pair of connected sockets. Store the file descriptor
319 // for one end in the operation and enqueue the operation. The
320 // file descriptor for the other end wil be returned to the client.
321 if (res == 0) {
322 int s[2];
323 if (socketpair(PF_UNIX, SOCK_STREAM, 0, s) < 0) {
324 delete op;
325 res = (jint)SolarisAttachListener::ATTACH_ERROR_RESOURCE;
326 } else {
327 op->set_socket(s[0]);
328 return_fd = s[1];
329 SolarisAttachListener::enqueue(op);
330 }
331 }
332
333 // Return 0 (success) + file descriptor, or non-0 (error)
334 if (res == 0) {
335 door_desc_t desc;
336 desc.d_attributes = DOOR_DESCRIPTOR;
337 desc.d_data.d_desc.d_descriptor = return_fd;
338 door_return((char*)&res, sizeof(res), &desc, 1);
339 } else {
340 door_return((char*)&res, sizeof(res), NULL, 0);
341 }
342 }
343 }
344
345 // atexit hook to detach the door and remove the file
346 extern "C" {
347 static void listener_cleanup() {
348 static int cleanup_done;
349 if (!cleanup_done) {
350 cleanup_done = 1;
351 int dd = SolarisAttachListener::door_descriptor();
352 if (dd >= 0) {
353 ::close(dd);
354 }
355 if (SolarisAttachListener::has_door_path()) {
356 char* path = SolarisAttachListener::door_path();
357 ::fdetach(path);
358 ::unlink(path);
359 }
360 }
361 }
362 }
363
364 // Create the door
365 int SolarisAttachListener::create_door() {
366 char door_path[PATH_MAX+1];
367 char initial_path[PATH_MAX+1];
368 int fd, res;
369
370 // register exit function
371 ::atexit(listener_cleanup);
372
373 // create the door descriptor
374 int dd = ::door_create(enqueue_proc, NULL, 0);
375 if (dd < 0) {
376 return -1;
377 }
378
379 // create initial file to attach door descriptor
380 snprintf(door_path, sizeof(door_path), "%s/.java_pid%d",
381 os::get_temp_directory(), os::current_process_id());
382 snprintf(initial_path, sizeof(initial_path), "%s.tmp", door_path);
383 RESTARTABLE(::creat(initial_path, S_IRUSR | S_IWUSR), fd);
384 if (fd == -1) {
385 debug_only(warning("attempt to create %s failed", initial_path));
386 ::door_revoke(dd);
387 return -1;
388 }
389 assert(fd >= 0, "bad file descriptor");
390 RESTARTABLE(::close(fd), res);
391
392 // attach the door descriptor to the file
393 if ((res = ::fattach(dd, initial_path)) == -1) {
394 // if busy then detach and try again
395 if (errno == EBUSY) {
396 ::fdetach(initial_path);
397 res = ::fattach(dd, initial_path);
398 }
399 if (res == -1) {
400 ::door_revoke(dd);
401 dd = -1;
402 }
403 }
404
405 // rename file so that clients can attach
406 if (dd >= 0) {
407 if (::rename(initial_path, door_path) == -1) {
408 RESTARTABLE(::close(dd), res);
409 ::fdetach(initial_path);
410 dd = -1;
411 }
412 }
413 if (dd >= 0) {
414 set_door_descriptor(dd);
415 set_door_path(door_path);
416 } else {
417 // unable to create door, attach it to file, or rename file into place
418 ::unlink(initial_path);
419 return -1;
420 }
421
422 return 0;
423 }
424
425 // Initialization - create the door, locks, and other initialization
426 int SolarisAttachListener::init() {
427 if (create_door()) {
428 return -1;
429 }
430
431 int status = os::Solaris::mutex_init(&_mutex);
432 assert_status(status==0, status, "mutex_init");
433
434 status = ::sema_init(&_wakeup, 0, NULL, NULL);
435 assert_status(status==0, status, "sema_init");
436
437 set_head(NULL);
438 set_tail(NULL);
439
440 return 0;
441 }
442
443 // Dequeue an operation
444 SolarisAttachOperation* SolarisAttachListener::dequeue() {
445 for (;;) {
446 int res;
447
448 // wait for somebody to enqueue something
449 while ((res = ::sema_wait(wakeup())) == EINTR)
450 ;
451 if (res) {
452 warning("sema_wait failed: %s", strerror(res));
453 return NULL;
454 }
455
456 // lock the list
457 res = os::Solaris::mutex_lock(mutex());
458 assert(res == 0, "mutex_lock failed");
459
460 // remove the head of the list
461 SolarisAttachOperation* op = head();
462 if (op != NULL) {
463 set_head(op->next());
464 if (head() == NULL) {
465 set_tail(NULL);
466 }
467 }
468
469 // unlock
470 os::Solaris::mutex_unlock(mutex());
471
472 // if we got an operation when return it.
473 if (op != NULL) {
474 return op;
475 }
476 }
477 }
478
479 // Enqueue an operation
480 void SolarisAttachListener::enqueue(SolarisAttachOperation* op) {
481 // lock list
482 int res = os::Solaris::mutex_lock(mutex());
483 assert(res == 0, "mutex_lock failed");
484
485 // enqueue at tail
486 op->set_next(NULL);
487 if (head() == NULL) {
488 set_head(op);
489 } else {
490 tail()->set_next(op);
491 }
492 set_tail(op);
493
494 // wakeup the attach listener
495 RESTARTABLE(::sema_post(wakeup()), res);
496 assert(res == 0, "sema_post failed");
497
498 // unlock
499 os::Solaris::mutex_unlock(mutex());
500 }
501
502
503 // support function - writes the (entire) buffer to a socket
504 static int write_fully(int s, char* buf, int len) {
505 do {
506 int n = ::write(s, buf, len);
507 if (n == -1) {
508 if (errno != EINTR) return -1;
509 } else {
510 buf += n;
511 len -= n;
512 }
513 }
514 while (len > 0);
515 return 0;
516 }
517
518 // Complete an operation by sending the operation result and any result
519 // output to the client. At this time the socket is in blocking mode so
520 // potentially we can block if there is a lot of data and the client is
521 // non-responsive. For most operations this is a non-issue because the
522 // default send buffer is sufficient to buffer everything. In the future
523 // if there are operations that involves a very big reply then it the
524 // socket could be made non-blocking and a timeout could be used.
525
526 void SolarisAttachOperation::complete(jint res, bufferedStream* st) {
527 if (this->socket() >= 0) {
528 JavaThread* thread = JavaThread::current();
529 ThreadBlockInVM tbivm(thread);
530
531 thread->set_suspend_equivalent();
532 // cleared by handle_special_suspend_equivalent_condition() or
533 // java_suspend_self() via check_and_wait_while_suspended()
534
535 // write operation result
536 char msg[32];
537 sprintf(msg, "%d\n", res);
538 int rc = write_fully(this->socket(), msg, strlen(msg));
539
540 // write any result data
541 if (rc == 0) {
542 write_fully(this->socket(), (char*) st->base(), st->size());
543 ::shutdown(this->socket(), 2);
544 }
545
546 // close socket and we're done
547 RESTARTABLE(::close(this->socket()), rc);
548
549 // were we externally suspended while we were waiting?
550 thread->check_and_wait_while_suspended();
551 }
552 delete this;
553 }
554
555
556 // AttachListener functions
557
558 AttachOperation* AttachListener::dequeue() {
559 JavaThread* thread = JavaThread::current();
560 ThreadBlockInVM tbivm(thread);
561
562 thread->set_suspend_equivalent();
563 // cleared by handle_special_suspend_equivalent_condition() or
564 // java_suspend_self() via check_and_wait_while_suspended()
565
566 AttachOperation* op = SolarisAttachListener::dequeue();
567
568 // were we externally suspended while we were waiting?
569 thread->check_and_wait_while_suspended();
570
571 return op;
572 }
573
574 int AttachListener::pd_init() {
575 JavaThread* thread = JavaThread::current();
576 ThreadBlockInVM tbivm(thread);
577
578 thread->set_suspend_equivalent();
579 // cleared by handle_special_suspend_equivalent_condition() or
580 // java_suspend_self()
581
582 int ret_code = SolarisAttachListener::init();
583
584 // were we externally suspended while we were waiting?
585 thread->check_and_wait_while_suspended();
586
587 return ret_code;
588 }
589
590 // Attach Listener is started lazily except in the case when
591 // +ReduseSignalUsage is used
592 bool AttachListener::init_at_startup() {
593 if (ReduceSignalUsage) {
594 return true;
595 } else {
596 return false;
597 }
598 }
599
600 // If the file .attach_pid<pid> exists in the working directory
601 // or /tmp then this is the trigger to start the attach mechanism
602 bool AttachListener::is_init_trigger() {
603 if (init_at_startup() || is_initialized()) {
604 return false; // initialized at startup or already initialized
605 }
606 char fn[PATH_MAX+1];
607 sprintf(fn, ".attach_pid%d", os::current_process_id());
608 int ret;
609 struct stat64 st;
610 RESTARTABLE(::stat64(fn, &st), ret);
611 if (ret == -1) {
612 snprintf(fn, sizeof(fn), "%s/.attach_pid%d",
613 os::get_temp_directory(), os::current_process_id());
614 RESTARTABLE(::stat64(fn, &st), ret);
615 }
616 if (ret == 0) {
617 // simple check to avoid starting the attach mechanism when
618 // a bogus user creates the file
619 if (st.st_uid == geteuid()) {
620 init();
621 return true;
622 }
623 }
624 return false;
625 }
626
627 // if VM aborts then detach/cleanup
628 void AttachListener::abort() {
629 listener_cleanup();
630 }
631
632 void AttachListener::pd_data_dump() {
633 os::signal_notify(SIGQUIT);
634 }
635
636 static jint enable_dprobes(AttachOperation* op, outputStream* out) {
637 const char* probe = op->arg(0);
638 if (probe == NULL || probe[0] == '\0') {
639 out->print_cr("No probe specified");
640 return JNI_ERR;
641 } else {
642 int probe_typess = atoi(probe);
643 if (errno) {
644 out->print_cr("invalid probe type");
645 return JNI_ERR;
646 } else {
647 DTrace::enable_dprobes(probe_typess);
648 return JNI_OK;
649 }
650 }
651 }
652
653 // platform specific operations table
654 static AttachOperationFunctionInfo funcs[] = {
655 { "enabledprobes", enable_dprobes },
656 { NULL, NULL }
657 };
658
659 AttachOperationFunctionInfo* AttachListener::pd_find_operation(const char* name) {
660 int i;
661 for (i = 0; funcs[i].name != NULL; i++) {
662 if (strcmp(funcs[i].name, name) == 0) {
663 return &funcs[i];
664 }
665 }
666 return NULL;
667 }
668
669 // Solaris specific global flag set. Currently, we support only
670 // changing ExtendedDTraceProbes flag.
671 jint AttachListener::pd_set_flag(AttachOperation* op, outputStream* out) {
672 const char* name = op->arg(0);
673 assert(name != NULL, "flag name should not be null");
674 bool flag = true;
675 const char* arg1;
676 if ((arg1 = op->arg(1)) != NULL) {
677 flag = (atoi(arg1) != 0);
678 if (errno) {
679 out->print_cr("flag value has to be an integer");
680 return JNI_ERR;
681 }
682 }
683
684 if (strcmp(name, "ExtendedDTraceProbes") == 0) {
685 DTrace::set_extended_dprobes(flag);
686 return JNI_OK;
687 }
688
689 if (strcmp(name, "DTraceMonitorProbes") == 0) {
690 DTrace::set_monitor_dprobes(flag);
691 return JNI_OK;
692 }
693
694 out->print_cr("flag '%s' cannot be changed", name);
695 return JNI_ERR;
696 }
697
698 void AttachListener::pd_detachall() {
699 DTrace::detach_all_clients();
700 }