1 /*
2 * Copyright (c) 2005, 2016, 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 "precompiled.hpp"
26 #include "runtime/interfaceSupport.hpp"
27 #include "runtime/os.inline.hpp"
28 #include "services/attachListener.hpp"
29 #include "services/dtraceAttacher.hpp"
30
31 #include <door.h>
32 #include <limits.h>
33 #include <string.h>
34 #include <signal.h>
35 #include <sys/types.h>
36 #include <sys/socket.h>
37 #include <sys/stat.h>
38
39 // stropts.h uses STR in stream ioctl defines
40 #undef STR
41 #include <stropts.h>
42 #undef STR
43 #define STR(a) #a
44
45 // The attach mechanism on Solaris is implemented using the Doors IPC
46 // mechanism. The first tool to attempt to attach causes the attach
47 // listener thread to startup. This thread creats a door that is
48 // associated with a function that enqueues an operation to the attach
49 // listener. The door is attached to a file in the file system so that
50 // client (tools) can locate it. To enqueue an operation to the VM the
51 // client calls through the door which invokes the enqueue function in
52 // this process. The credentials of the client are checked and if the
53 // effective uid matches this process then the operation is enqueued.
54 // When an operation completes the attach listener is required to send the
55 // operation result and any result data to the client. In this implementation
56 // the result is returned via a UNIX domain socket. A pair of connected
57 // sockets (socketpair) is created in the enqueue function and the file
58 // descriptor for one of the sockets is returned to the client as the
59 // return from the door call. The other end is retained in this process.
60 // When the operation completes the result is sent to the client and
61 // the socket is closed.
62
63 // forward reference
64 class SolarisAttachOperation;
65
66 class SolarisAttachListener: AllStatic {
67 private:
68
69 // the path to which we attach the door file descriptor
70 static char _door_path[PATH_MAX+1];
71 static volatile bool _has_door_path;
72
73 // door descriptor returned by door_create
74 static int _door_descriptor;
75
76 static void set_door_path(char* path) {
77 if (path == NULL) {
78 _has_door_path = false;
79 } else {
80 strncpy(_door_path, path, PATH_MAX);
81 _door_path[PATH_MAX] = '\0'; // ensure it's nul terminated
82 _has_door_path = true;
83 }
84 }
85
86 static void set_door_descriptor(int dd) { _door_descriptor = dd; }
87
88 // mutex to protect operation list
89 static mutex_t _mutex;
90
91 // semaphore to wakeup listener thread
92 static sema_t _wakeup;
93
94 static mutex_t* mutex() { return &_mutex; }
95 static sema_t* wakeup() { return &_wakeup; }
96
97 // enqueued operation list
98 static SolarisAttachOperation* _head;
99 static SolarisAttachOperation* _tail;
100
101 static SolarisAttachOperation* head() { return _head; }
102 static void set_head(SolarisAttachOperation* head) { _head = head; }
103
104 static SolarisAttachOperation* tail() { return _tail; }
105 static void set_tail(SolarisAttachOperation* tail) { _tail = tail; }
106
107 // create the door
108 static int create_door();
109
110 public:
111 enum {
112 ATTACH_PROTOCOL_VER = 1 // protocol version
113 };
114 enum {
115 ATTACH_ERROR_BADREQUEST = 100, // error code returned by
116 ATTACH_ERROR_BADVERSION = 101, // the door call
117 ATTACH_ERROR_RESOURCE = 102,
118 ATTACH_ERROR_INTERNAL = 103,
119 ATTACH_ERROR_DENIED = 104
120 };
121
122 // initialize the listener
123 static int init();
124
125 static bool has_door_path() { return _has_door_path; }
126 static char* door_path() { return _door_path; }
127 static int door_descriptor() { return _door_descriptor; }
128
129 // enqueue an operation
130 static void enqueue(SolarisAttachOperation* op);
131
132 // dequeue an operation
133 static SolarisAttachOperation* dequeue();
134 };
135
136
137 // SolarisAttachOperation is an AttachOperation that additionally encapsulates
138 // a socket connection to the requesting client/tool. SolarisAttachOperation
139 // can additionally be held in a linked list.
140
141 class SolarisAttachOperation: public AttachOperation {
142 private:
143 friend class SolarisAttachListener;
144
145 // connection to client
146 int _socket;
147
148 // linked list support
149 SolarisAttachOperation* _next;
150
151 SolarisAttachOperation* next() { return _next; }
152 void set_next(SolarisAttachOperation* next) { _next = next; }
153
154 public:
155 void complete(jint res, bufferedStream* st);
156
157 int socket() const { return _socket; }
158 void set_socket(int s) { _socket = s; }
159
160 SolarisAttachOperation(char* name) : AttachOperation(name) {
161 set_socket(-1);
162 set_next(NULL);
163 }
164 };
165
166 // statics
167 char SolarisAttachListener::_door_path[PATH_MAX+1];
168 volatile bool SolarisAttachListener::_has_door_path;
169 int SolarisAttachListener::_door_descriptor = -1;
170 mutex_t SolarisAttachListener::_mutex;
171 sema_t SolarisAttachListener::_wakeup;
172 SolarisAttachOperation* SolarisAttachListener::_head = NULL;
173 SolarisAttachOperation* SolarisAttachListener::_tail = NULL;
174
175 // Supporting class to help split a buffer into individual components
176 class ArgumentIterator : public StackObj {
177 private:
178 char* _pos;
179 char* _end;
180 public:
181 ArgumentIterator(char* arg_buffer, size_t arg_size) {
182 _pos = arg_buffer;
183 _end = _pos + arg_size - 1;
184 }
185 char* next() {
186 if (*_pos == '\0') {
187 return NULL;
188 }
189 char* res = _pos;
190 char* next_pos = strchr(_pos, '\0');
191 if (next_pos < _end) {
192 next_pos++;
193 }
194 _pos = next_pos;
195 return res;
196 }
197 };
198
199 // Calls from the door function to check that the client credentials
200 // match this process. Returns 0 if credentials okay, otherwise -1.
201 static int check_credentials() {
202 ucred_t *cred_info = NULL;
203 int ret = -1; // deny by default
204
205 // get client credentials
206 if (door_ucred(&cred_info) == -1) {
207 return -1; // unable to get them, deny
208 }
209
210 // get our euid/eguid (probably could cache these)
211 uid_t euid = geteuid();
212 gid_t egid = getegid();
213
214 // get euid/egid from ucred_free
215 uid_t ucred_euid = ucred_geteuid(cred_info);
216 gid_t ucred_egid = ucred_getegid(cred_info);
217
218 // check that the effective uid/gid matches
219 if (ucred_euid == euid && ucred_egid == egid) {
220 ret = 0; // allow
221 }
222
223 ucred_free(cred_info);
224 return ret;
225 }
226
227
228 // Parses the argument buffer to create an AttachOperation that we should
229 // enqueue to the attach listener.
230 // The buffer is expected to be formatted as follows:
231 // <ver>0<cmd>0<arg>0<arg>0<arg>0
232 // where <ver> is the version number (must be "1"), <cmd> is the command
233 // name ("load, "datadump", ...) and <arg> is an argument.
234 //
235 static SolarisAttachOperation* create_operation(char* argp, size_t arg_size, int* err) {
236 // assume bad request until parsed
237 *err = SolarisAttachListener::ATTACH_ERROR_BADREQUEST;
238
239 if (arg_size < 2 || argp[arg_size-1] != '\0') {
240 return NULL; // no ver or not null terminated
241 }
242
243 // Use supporting class to iterate over the buffer
244 ArgumentIterator args(argp, arg_size);
245
246 // First check the protocol version
247 char* ver = args.next();
248 if (ver == NULL) {
249 return NULL;
250 }
251 if (atoi(ver) != SolarisAttachListener::ATTACH_PROTOCOL_VER) {
252 *err = SolarisAttachListener::ATTACH_ERROR_BADVERSION;
253 return NULL;
254 }
255
256 // Get command name and create the operation
257 char* name = args.next();
258 if (name == NULL || strlen(name) > AttachOperation::name_length_max) {
259 return NULL;
260 }
261 SolarisAttachOperation* op = new SolarisAttachOperation(name);
262
263 // Iterate over the arguments
264 for (int i=0; i<AttachOperation::arg_count_max; i++) {
265 char* arg = args.next();
266 if (arg == NULL) {
267 op->set_arg(i, NULL);
268 } else {
269 if (strlen(arg) > AttachOperation::arg_length_max) {
270 delete op;
271 return NULL;
272 }
273 op->set_arg(i, arg);
274 }
275 }
276
277 // return operation
278 *err = 0;
279 return op;
280 }
281
282 // create special operation to indicate all clients have detached
283 static SolarisAttachOperation* create_detachall_operation() {
284 return new SolarisAttachOperation(AttachOperation::detachall_operation_name());
285 }
286
287 // This is door function which the client executes via a door_call.
288 extern "C" {
289 static void enqueue_proc(void* cookie, char* argp, size_t arg_size,
290 door_desc_t* dt, uint_t n_desc)
291 {
292 int return_fd = -1;
293 SolarisAttachOperation* op = NULL;
294
295 // no listener
296 jint res = 0;
297 if (!AttachListener::is_initialized()) {
298 // how did we get here?
299 debug_only(warning("door_call when not enabled"));
300 res = (jint)SolarisAttachListener::ATTACH_ERROR_INTERNAL;
301 }
302
303 // check client credentials
304 if (res == 0) {
305 if (check_credentials() != 0) {
306 res = (jint)SolarisAttachListener::ATTACH_ERROR_DENIED;
307 }
308 }
309
310 // if we are stopped at ShowMessageBoxOnError then maybe we can
311 // load a diagnostic library
312 if (res == 0 && is_error_reported()) {
313 if (ShowMessageBoxOnError) {
314 // TBD - support loading of diagnostic library here
315 }
316
317 // can't enqueue operation after fatal error
318 res = (jint)SolarisAttachListener::ATTACH_ERROR_RESOURCE;
319 }
320
321 // create the operation
322 if (res == 0) {
323 int err;
324 op = create_operation(argp, arg_size, &err);
325 res = (op == NULL) ? (jint)err : 0;
326 }
327
328 // create a pair of connected sockets. Store the file descriptor
329 // for one end in the operation and enqueue the operation. The
330 // file descriptor for the other end wil be returned to the client.
331 if (res == 0) {
332 int s[2];
333 if (socketpair(PF_UNIX, SOCK_STREAM, 0, s) < 0) {
334 delete op;
335 res = (jint)SolarisAttachListener::ATTACH_ERROR_RESOURCE;
336 } else {
337 op->set_socket(s[0]);
338 return_fd = s[1];
339 SolarisAttachListener::enqueue(op);
340 }
341 }
342
343 // Return 0 (success) + file descriptor, or non-0 (error)
344 if (res == 0) {
345 door_desc_t desc;
346 // DOOR_RELEASE flag makes sure fd is closed after passing it to
347 // the client. See door_return(3DOOR) man page.
348 desc.d_attributes = DOOR_DESCRIPTOR | DOOR_RELEASE;
349 desc.d_data.d_desc.d_descriptor = return_fd;
350 door_return((char*)&res, sizeof(res), &desc, 1);
351 } else {
352 door_return((char*)&res, sizeof(res), NULL, 0);
353 }
354 }
355 }
356
357 // atexit hook to detach the door and remove the file
358 extern "C" {
359 static void listener_cleanup() {
360 static int cleanup_done;
361 if (!cleanup_done) {
362 cleanup_done = 1;
363 int dd = SolarisAttachListener::door_descriptor();
364 if (dd >= 0) {
365 ::close(dd);
366 }
367 if (SolarisAttachListener::has_door_path()) {
368 char* path = SolarisAttachListener::door_path();
369 ::fdetach(path);
370 ::unlink(path);
371 }
372 }
373 }
374 }
375
376 // Create the door
377 int SolarisAttachListener::create_door() {
378 char door_path[PATH_MAX+1];
379 char initial_path[PATH_MAX+1];
380 int fd, res;
381
382 // register exit function
383 ::atexit(listener_cleanup);
384
385 // create the door descriptor
386 int dd = ::door_create(enqueue_proc, NULL, 0);
387 if (dd < 0) {
388 return -1;
389 }
390
391 // create initial file to attach door descriptor
392 snprintf(door_path, sizeof(door_path), "%s/.java_pid%d",
393 os::get_temp_directory(), os::current_process_id());
394 snprintf(initial_path, sizeof(initial_path), "%s.tmp", door_path);
395 RESTARTABLE(::creat(initial_path, S_IRUSR | S_IWUSR), fd);
396 if (fd == -1) {
397 log_debug(attach)("attempt to create door file %s failed (%d)", initial_path, errno);
398 ::door_revoke(dd);
399 return -1;
400 }
401 assert(fd >= 0, "bad file descriptor");
402 ::close(fd);
403
404 // attach the door descriptor to the file
405 if ((res = ::fattach(dd, initial_path)) == -1) {
406 // if busy then detach and try again
407 if (errno == EBUSY) {
408 ::fdetach(initial_path);
409 res = ::fattach(dd, initial_path);
410 }
411 if (res == -1) {
412 log_debug(attach)("unable to create door - fattach failed (%d)", errno);
413 ::door_revoke(dd);
414 dd = -1;
415 }
416 }
417
418 // rename file so that clients can attach
419 if (dd >= 0) {
420 if (::rename(initial_path, door_path) == -1) {
421 ::close(dd);
422 ::fdetach(initial_path);
423 log_debug(attach)("unable to create door - rename %s to %s failed (%d)", errno);
424 dd = -1;
425 }
426 }
427 if (dd >= 0) {
428 set_door_descriptor(dd);
429 set_door_path(door_path);
430 log_trace(attach)("door file %s created succesfully", door_path);
431 } else {
432 // unable to create door, attach it to file, or rename file into place
433 ::unlink(initial_path);
434 return -1;
435 }
436
437 return 0;
438 }
439
440 // Initialization - create the door, locks, and other initialization
441 int SolarisAttachListener::init() {
442 if (create_door()) {
443 return -1;
444 }
445
446 int status = os::Solaris::mutex_init(&_mutex);
447 assert_status(status==0, status, "mutex_init");
448
449 status = ::sema_init(&_wakeup, 0, NULL, NULL);
450 assert_status(status==0, status, "sema_init");
451
452 set_head(NULL);
453 set_tail(NULL);
454
455 return 0;
456 }
457
458 // Dequeue an operation
459 SolarisAttachOperation* SolarisAttachListener::dequeue() {
460 for (;;) {
461 int res;
462
463 // wait for somebody to enqueue something
464 while ((res = ::sema_wait(wakeup())) == EINTR)
465 ;
466 if (res) {
467 warning("sema_wait failed: %s", os::strerror(res));
468 return NULL;
469 }
470
471 // lock the list
472 res = os::Solaris::mutex_lock(mutex());
473 assert(res == 0, "mutex_lock failed");
474
475 // remove the head of the list
476 SolarisAttachOperation* op = head();
477 if (op != NULL) {
478 set_head(op->next());
479 if (head() == NULL) {
480 set_tail(NULL);
481 }
482 }
483
484 // unlock
485 os::Solaris::mutex_unlock(mutex());
486
487 // if we got an operation when return it.
488 if (op != NULL) {
489 return op;
490 }
491 }
492 }
493
494 // Enqueue an operation
495 void SolarisAttachListener::enqueue(SolarisAttachOperation* op) {
496 // lock list
497 int res = os::Solaris::mutex_lock(mutex());
498 assert(res == 0, "mutex_lock failed");
499
500 // enqueue at tail
501 op->set_next(NULL);
502 if (head() == NULL) {
503 set_head(op);
504 } else {
505 tail()->set_next(op);
506 }
507 set_tail(op);
508
509 // wakeup the attach listener
510 RESTARTABLE(::sema_post(wakeup()), res);
511 assert(res == 0, "sema_post failed");
512
513 // unlock
514 os::Solaris::mutex_unlock(mutex());
515 }
516
517
518 // support function - writes the (entire) buffer to a socket
519 static int write_fully(int s, char* buf, int len) {
520 do {
521 int n = ::write(s, buf, len);
522 if (n == -1) {
523 if (errno != EINTR) return -1;
524 } else {
525 buf += n;
526 len -= n;
527 }
528 }
529 while (len > 0);
530 return 0;
531 }
532
533 // Complete an operation by sending the operation result and any result
534 // output to the client. At this time the socket is in blocking mode so
535 // potentially we can block if there is a lot of data and the client is
536 // non-responsive. For most operations this is a non-issue because the
537 // default send buffer is sufficient to buffer everything. In the future
538 // if there are operations that involves a very big reply then it the
539 // socket could be made non-blocking and a timeout could be used.
540
541 void SolarisAttachOperation::complete(jint res, bufferedStream* st) {
542 if (this->socket() >= 0) {
543 JavaThread* thread = JavaThread::current();
544 ThreadBlockInVM tbivm(thread);
545
546 thread->set_suspend_equivalent();
547 // cleared by handle_special_suspend_equivalent_condition() or
548 // java_suspend_self() via check_and_wait_while_suspended()
549
550 // write operation result
551 char msg[32];
552 sprintf(msg, "%d\n", res);
553 int rc = write_fully(this->socket(), msg, strlen(msg));
554
555 // write any result data
556 if (rc == 0) {
557 write_fully(this->socket(), (char*) st->base(), st->size());
558 ::shutdown(this->socket(), 2);
559 }
560
561 // close socket and we're done
562 ::close(this->socket());
563
564 // were we externally suspended while we were waiting?
565 thread->check_and_wait_while_suspended();
566 }
567 delete this;
568 }
569
570
571 // AttachListener functions
572
573 AttachOperation* AttachListener::dequeue() {
574 JavaThread* thread = JavaThread::current();
575 ThreadBlockInVM tbivm(thread);
576
577 thread->set_suspend_equivalent();
578 // cleared by handle_special_suspend_equivalent_condition() or
579 // java_suspend_self() via check_and_wait_while_suspended()
580
581 AttachOperation* op = SolarisAttachListener::dequeue();
582
583 // were we externally suspended while we were waiting?
584 thread->check_and_wait_while_suspended();
585
586 return op;
587 }
588
589
590 // Performs initialization at vm startup
591 // For Solaris we remove any stale .java_pid file which could cause
592 // an attaching process to think we are ready to receive a door_call
593 // before we are properly initialized
594
595 void AttachListener::vm_start() {
596 char fn[PATH_MAX+1];
597 struct stat64 st;
598 int ret;
599
600 int n = snprintf(fn, sizeof(fn), "%s/.java_pid%d",
601 os::get_temp_directory(), os::current_process_id());
602 assert(n < sizeof(fn), "java_pid file name buffer overflow");
603
604 RESTARTABLE(::stat64(fn, &st), ret);
605 if (ret == 0) {
606 ret = ::unlink(fn);
607 if (ret == -1) {
608 log_debug(attach)("Failed to remove stale attach pid file at %s", fn);
609 }
610 }
611 }
612
613 int AttachListener::pd_init() {
614 JavaThread* thread = JavaThread::current();
615 ThreadBlockInVM tbivm(thread);
616
617 thread->set_suspend_equivalent();
618 // cleared by handle_special_suspend_equivalent_condition() or
619 // java_suspend_self()
620
621 int ret_code = SolarisAttachListener::init();
622
623 // were we externally suspended while we were waiting?
624 thread->check_and_wait_while_suspended();
625
626 return ret_code;
627 }
628
629 // Attach Listener is started lazily except in the case when
630 // +ReduseSignalUsage is used
631 bool AttachListener::init_at_startup() {
632 if (ReduceSignalUsage) {
633 return true;
634 } else {
635 return false;
636 }
637 }
638
639 // If the file .attach_pid<pid> exists in the working directory
640 // or /tmp then this is the trigger to start the attach mechanism
641 bool AttachListener::is_init_trigger() {
642 if (init_at_startup() || is_initialized()) {
643 return false; // initialized at startup or already initialized
644 }
645 char fn[PATH_MAX+1];
646 sprintf(fn, ".attach_pid%d", os::current_process_id());
647 int ret;
648 struct stat64 st;
649 RESTARTABLE(::stat64(fn, &st), ret);
650 if (ret == -1) {
651 log_trace(attach)("Failed to find attach file: %s, trying alternate", fn);
652 snprintf(fn, sizeof(fn), "%s/.attach_pid%d",
653 os::get_temp_directory(), os::current_process_id());
654 RESTARTABLE(::stat64(fn, &st), ret);
655 if (ret == -1) {
656 log_debug(attach)("Failed to find attach file: %s", fn);
657 }
658 }
659 if (ret == 0) {
660 // simple check to avoid starting the attach mechanism when
661 // a bogus user creates the file
662 if (st.st_uid == geteuid()) {
663 init();
664 return true;
665 }
666 }
667 return false;
668 }
669
670 // if VM aborts then detach/cleanup
671 void AttachListener::abort() {
672 listener_cleanup();
673 }
674
675 void AttachListener::pd_data_dump() {
676 os::signal_notify(SIGQUIT);
677 }
678
679 static jint enable_dprobes(AttachOperation* op, outputStream* out) {
680 const char* probe = op->arg(0);
681 if (probe == NULL || probe[0] == '\0') {
682 out->print_cr("No probe specified");
683 return JNI_ERR;
684 } else {
685 char *end;
686 long val = strtol(probe, &end, 10);
687 if (end == probe || val < 0 || val > INT_MAX) {
688 out->print_cr("invalid probe type");
689 return JNI_ERR;
690 } else {
691 int probe_typess = (int) val;
692 DTrace::enable_dprobes(probe_typess);
693 return JNI_OK;
694 }
695 }
696 }
697
698 // platform specific operations table
699 static AttachOperationFunctionInfo funcs[] = {
700 { "enabledprobes", enable_dprobes },
701 { NULL, NULL }
702 };
703
704 AttachOperationFunctionInfo* AttachListener::pd_find_operation(const char* name) {
705 int i;
706 for (i = 0; funcs[i].name != NULL; i++) {
707 if (strcmp(funcs[i].name, name) == 0) {
708 return &funcs[i];
709 }
710 }
711 return NULL;
712 }
713
714 // Solaris specific global flag set. Currently, we support only
715 // changing ExtendedDTraceProbes flag.
716 jint AttachListener::pd_set_flag(AttachOperation* op, outputStream* out) {
717 const char* name = op->arg(0);
718 assert(name != NULL, "flag name should not be null");
719 bool flag = true;
720 const char* arg1;
721 if ((arg1 = op->arg(1)) != NULL) {
722 char *end;
723 flag = (strtol(arg1, &end, 10) != 0);
724 if (arg1 == end) {
725 out->print_cr("flag value has to be an integer");
726 return JNI_ERR;
727 }
728 }
729
730 if (strcmp(name, "ExtendedDTraceProbes") == 0) {
731 DTrace::set_extended_dprobes(flag);
732 return JNI_OK;
733 }
734
735 if (strcmp(name, "DTraceMonitorProbes") == 0) {
736 DTrace::set_monitor_dprobes(flag);
737 return JNI_OK;
738 }
739
740 out->print_cr("flag '%s' cannot be changed", name);
741 return JNI_ERR;
742 }
743
744 void AttachListener::pd_detachall() {
745 DTrace::detach_all_clients();
746 }