1 /*
2 * Copyright (c) 2005, 2017, 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.inline.hpp"
27 #include "runtime/os.inline.hpp"
28 #include "services/attachListener.hpp"
29 #include "services/dtraceAttacher.hpp"
30 #include "utilities/vmError.hpp"
31
32 #include <door.h>
33 #include <limits.h>
34 #include <string.h>
35 #include <signal.h>
36 #include <sys/types.h>
37 #include <sys/socket.h>
38 #include <sys/stat.h>
39
40 // stropts.h uses STR in stream ioctl defines
41 #undef STR
42 #include <stropts.h>
43 #undef STR
44 #define STR(a) #a
45
46 // The attach mechanism on Solaris is implemented using the Doors IPC
47 // mechanism. The first tool to attempt to attach causes the attach
48 // listener thread to startup. This thread creats a door that is
49 // associated with a function that enqueues an operation to the attach
50 // listener. The door is attached to a file in the file system so that
51 // client (tools) can locate it. To enqueue an operation to the VM the
52 // client calls through the door which invokes the enqueue function in
53 // this process. The credentials of the client are checked and if the
54 // effective uid matches this process then the operation is enqueued.
55 // When an operation completes the attach listener is required to send the
56 // operation result and any result data to the client. In this implementation
57 // the result is returned via a UNIX domain socket. A pair of connected
58 // sockets (socketpair) is created in the enqueue function and the file
59 // descriptor for one of the sockets is returned to the client as the
60 // return from the door call. The other end is retained in this process.
61 // When the operation completes the result is sent to the client and
62 // the socket is closed.
63
64 // forward reference
65 class SolarisAttachOperation;
66
67 class SolarisAttachListener: AllStatic {
68 private:
69
70 // the path to which we attach the door file descriptor
71 static char _door_path[PATH_MAX+1];
72 static volatile bool _has_door_path;
73
74 // door descriptor returned by door_create
75 static int _door_descriptor;
76
77 static void set_door_path(char* path) {
78 if (path == NULL) {
79 _has_door_path = false;
80 } else {
81 strncpy(_door_path, path, PATH_MAX);
82 _door_path[PATH_MAX] = '\0'; // ensure it's nul terminated
83 _has_door_path = true;
84 }
85 }
86
87 static void set_door_descriptor(int dd) { _door_descriptor = dd; }
88
89 // mutex to protect operation list
90 static mutex_t _mutex;
91
92 // semaphore to wakeup listener thread
93 static sema_t _wakeup;
94
95 static mutex_t* mutex() { return &_mutex; }
96 static sema_t* wakeup() { return &_wakeup; }
97
98 // enqueued operation list
99 static SolarisAttachOperation* _head;
100 static SolarisAttachOperation* _tail;
101
102 static SolarisAttachOperation* head() { return _head; }
103 static void set_head(SolarisAttachOperation* head) { _head = head; }
104
105 static SolarisAttachOperation* tail() { return _tail; }
106 static void set_tail(SolarisAttachOperation* tail) { _tail = tail; }
107
108 // create the door
109 static int create_door();
110
111 public:
112 enum {
113 ATTACH_PROTOCOL_VER = 1 // protocol version
114 };
115 enum {
116 ATTACH_ERROR_BADREQUEST = 100, // error code returned by
117 ATTACH_ERROR_BADVERSION = 101, // the door call
118 ATTACH_ERROR_RESOURCE = 102,
119 ATTACH_ERROR_INTERNAL = 103,
120 ATTACH_ERROR_DENIED = 104
121 };
122
123 // initialize the listener
124 static int init();
125
126 static bool has_door_path() { return _has_door_path; }
127 static char* door_path() { return _door_path; }
128 static int door_descriptor() { return _door_descriptor; }
129
130 // enqueue an operation
131 static void enqueue(SolarisAttachOperation* op);
132
133 // dequeue an operation
134 static SolarisAttachOperation* dequeue();
135 };
136
137
138 // SolarisAttachOperation is an AttachOperation that additionally encapsulates
139 // a socket connection to the requesting client/tool. SolarisAttachOperation
140 // can additionally be held in a linked list.
141
142 class SolarisAttachOperation: public AttachOperation {
143 private:
144 friend class SolarisAttachListener;
145
146 // connection to client
147 int _socket;
148
149 // linked list support
150 SolarisAttachOperation* _next;
151
152 SolarisAttachOperation* next() { return _next; }
153 void set_next(SolarisAttachOperation* next) { _next = next; }
154
155 public:
156 void complete(jint res, bufferedStream* st);
157
158 int socket() const { return _socket; }
159 void set_socket(int s) { _socket = s; }
160
161 SolarisAttachOperation(char* name) : AttachOperation(name) {
162 set_socket(-1);
163 set_next(NULL);
164 }
165 };
166
167 // statics
168 char SolarisAttachListener::_door_path[PATH_MAX+1];
169 volatile bool SolarisAttachListener::_has_door_path;
170 int SolarisAttachListener::_door_descriptor = -1;
171 mutex_t SolarisAttachListener::_mutex;
172 sema_t SolarisAttachListener::_wakeup;
173 SolarisAttachOperation* SolarisAttachListener::_head = NULL;
174 SolarisAttachOperation* SolarisAttachListener::_tail = NULL;
175
176 // Supporting class to help split a buffer into individual components
177 class ArgumentIterator : public StackObj {
178 private:
179 char* _pos;
180 char* _end;
181 public:
182 ArgumentIterator(char* arg_buffer, size_t arg_size) {
183 _pos = arg_buffer;
184 _end = _pos + arg_size - 1;
185 }
186 char* next() {
187 if (*_pos == '\0') {
188 return NULL;
189 }
190 char* res = _pos;
191 char* next_pos = strchr(_pos, '\0');
192 if (next_pos < _end) {
193 next_pos++;
194 }
195 _pos = next_pos;
196 return res;
197 }
198 };
199
200 // Calls from the door function to check that the client credentials
201 // match this process. Returns 0 if credentials okay, otherwise -1.
202 static int check_credentials() {
203 ucred_t *cred_info = NULL;
204 int ret = -1; // deny by default
205
206 // get client credentials
207 if (door_ucred(&cred_info) == -1) {
208 return -1; // unable to get them, deny
209 }
210
211 // get our euid/eguid (probably could cache these)
212 uid_t euid = geteuid();
213 gid_t egid = getegid();
214
215 // get euid/egid from ucred_free
216 uid_t ucred_euid = ucred_geteuid(cred_info);
217 gid_t ucred_egid = ucred_getegid(cred_info);
218
219 // check that the effective uid/gid matches
220 if (ucred_euid == euid && ucred_egid == egid) {
221 ret = 0; // allow
222 }
223
224 ucred_free(cred_info);
225 return ret;
226 }
227
228
229 // Parses the argument buffer to create an AttachOperation that we should
230 // enqueue to the attach listener.
231 // The buffer is expected to be formatted as follows:
232 // <ver>0<cmd>0<arg>0<arg>0<arg>0
233 // where <ver> is the version number (must be "1"), <cmd> is the command
234 // name ("load, "datadump", ...) and <arg> is an argument.
235 //
236 static SolarisAttachOperation* create_operation(char* argp, size_t arg_size, int* err) {
237 // assume bad request until parsed
238 *err = SolarisAttachListener::ATTACH_ERROR_BADREQUEST;
239
240 if (arg_size < 2 || argp[arg_size-1] != '\0') {
241 return NULL; // no ver or not null terminated
242 }
243
244 // Use supporting class to iterate over the buffer
245 ArgumentIterator args(argp, arg_size);
246
247 // First check the protocol version
248 char* ver = args.next();
249 if (ver == NULL) {
250 return NULL;
251 }
252 if (atoi(ver) != SolarisAttachListener::ATTACH_PROTOCOL_VER) {
253 *err = SolarisAttachListener::ATTACH_ERROR_BADVERSION;
254 return NULL;
255 }
256
257 // Get command name and create the operation
258 char* name = args.next();
259 if (name == NULL || strlen(name) > AttachOperation::name_length_max) {
260 return NULL;
261 }
262 SolarisAttachOperation* op = new SolarisAttachOperation(name);
263
264 // Iterate over the arguments
265 for (int i=0; i<AttachOperation::arg_count_max; i++) {
266 char* arg = args.next();
267 if (arg == NULL) {
268 op->set_arg(i, NULL);
269 } else {
270 if (strlen(arg) > AttachOperation::arg_length_max) {
271 delete op;
272 return NULL;
273 }
274 op->set_arg(i, arg);
275 }
276 }
277
278 // return operation
279 *err = 0;
280 return op;
281 }
282
283 // create special operation to indicate all clients have detached
284 static SolarisAttachOperation* create_detachall_operation() {
285 return new SolarisAttachOperation(AttachOperation::detachall_operation_name());
286 }
287
288 // This is door function which the client executes via a door_call.
289 extern "C" {
290 static void enqueue_proc(void* cookie, char* argp, size_t arg_size,
291 door_desc_t* dt, uint_t n_desc)
292 {
293 int return_fd = -1;
294 SolarisAttachOperation* op = NULL;
295
296 // no listener
297 jint res = 0;
298 if (!AttachListener::is_initialized()) {
299 // how did we get here?
300 debug_only(warning("door_call when not enabled"));
301 res = (jint)SolarisAttachListener::ATTACH_ERROR_INTERNAL;
302 }
303
304 // check client credentials
305 if (res == 0) {
306 if (check_credentials() != 0) {
307 res = (jint)SolarisAttachListener::ATTACH_ERROR_DENIED;
308 }
309 }
310
311 // if we are stopped at ShowMessageBoxOnError then maybe we can
312 // load a diagnostic library
313 if (res == 0 && VMError::is_error_reported()) {
314 if (ShowMessageBoxOnError) {
315 // TBD - support loading of diagnostic library here
316 }
317
318 // can't enqueue operation after fatal error
319 res = (jint)SolarisAttachListener::ATTACH_ERROR_RESOURCE;
320 }
321
322 // create the operation
323 if (res == 0) {
324 int err;
325 op = create_operation(argp, arg_size, &err);
326 res = (op == NULL) ? (jint)err : 0;
327 }
328
329 // create a pair of connected sockets. Store the file descriptor
330 // for one end in the operation and enqueue the operation. The
331 // file descriptor for the other end wil be returned to the client.
332 if (res == 0) {
333 int s[2];
334 if (socketpair(PF_UNIX, SOCK_STREAM, 0, s) < 0) {
335 delete op;
336 res = (jint)SolarisAttachListener::ATTACH_ERROR_RESOURCE;
337 } else {
338 op->set_socket(s[0]);
339 return_fd = s[1];
340 SolarisAttachListener::enqueue(op);
341 }
342 }
343
344 // Return 0 (success) + file descriptor, or non-0 (error)
345 if (res == 0) {
346 door_desc_t desc;
347 // DOOR_RELEASE flag makes sure fd is closed after passing it to
348 // the client. See door_return(3DOOR) man page.
349 desc.d_attributes = DOOR_DESCRIPTOR | DOOR_RELEASE;
350 desc.d_data.d_desc.d_descriptor = return_fd;
351 door_return((char*)&res, sizeof(res), &desc, 1);
352 } else {
353 door_return((char*)&res, sizeof(res), NULL, 0);
354 }
355 }
356 }
357
358 // atexit hook to detach the door and remove the file
359 extern "C" {
360 static void listener_cleanup() {
361 static int cleanup_done;
362 if (!cleanup_done) {
363 cleanup_done = 1;
364 int dd = SolarisAttachListener::door_descriptor();
365 if (dd >= 0) {
366 ::close(dd);
367 }
368 if (SolarisAttachListener::has_door_path()) {
369 char* path = SolarisAttachListener::door_path();
370 ::fdetach(path);
371 ::unlink(path);
372 }
373 }
374 }
375 }
376
377 // Create the door
378 int SolarisAttachListener::create_door() {
379 char door_path[PATH_MAX+1];
380 char initial_path[PATH_MAX+1];
381 int fd, res;
382
383 // register exit function
384 ::atexit(listener_cleanup);
385
386 // create the door descriptor
387 int dd = ::door_create(enqueue_proc, NULL, 0);
388 if (dd < 0) {
389 return -1;
390 }
391
392 // create initial file to attach door descriptor
393 snprintf(door_path, sizeof(door_path), "%s/.java_pid%d",
394 os::get_temp_directory(), os::current_process_id());
395 snprintf(initial_path, sizeof(initial_path), "%s.tmp", door_path);
396 RESTARTABLE(::creat(initial_path, S_IRUSR | S_IWUSR), fd);
397 if (fd == -1) {
398 log_debug(attach)("attempt to create door file %s failed (%d)", initial_path, errno);
399 ::door_revoke(dd);
400 return -1;
401 }
402 assert(fd >= 0, "bad file descriptor");
403 ::close(fd);
404
405 // attach the door descriptor to the file
406 if ((res = ::fattach(dd, initial_path)) == -1) {
407 // if busy then detach and try again
408 if (errno == EBUSY) {
409 ::fdetach(initial_path);
410 res = ::fattach(dd, initial_path);
411 }
412 if (res == -1) {
413 log_debug(attach)("unable to create door - fattach failed (%d)", errno);
414 ::door_revoke(dd);
415 dd = -1;
416 }
417 }
418
419 // rename file so that clients can attach
420 if (dd >= 0) {
421 if (::rename(initial_path, door_path) == -1) {
422 ::close(dd);
423 ::fdetach(initial_path);
424 log_debug(attach)("unable to create door - rename %s to %s failed (%d)", errno);
425 dd = -1;
426 }
427 }
428 if (dd >= 0) {
429 set_door_descriptor(dd);
430 set_door_path(door_path);
431 log_trace(attach)("door file %s created succesfully", door_path);
432 } else {
433 // unable to create door, attach it to file, or rename file into place
434 ::unlink(initial_path);
435 return -1;
436 }
437
438 return 0;
439 }
440
441 // Initialization - create the door, locks, and other initialization
442 int SolarisAttachListener::init() {
443 if (create_door()) {
444 return -1;
445 }
446
447 int status = os::Solaris::mutex_init(&_mutex);
448 assert_status(status==0, status, "mutex_init");
449
450 status = ::sema_init(&_wakeup, 0, NULL, NULL);
451 assert_status(status==0, status, "sema_init");
452
453 set_head(NULL);
454 set_tail(NULL);
455
456 return 0;
457 }
458
459 // Dequeue an operation
460 SolarisAttachOperation* SolarisAttachListener::dequeue() {
461 for (;;) {
462 int res;
463
464 // wait for somebody to enqueue something
465 while ((res = ::sema_wait(wakeup())) == EINTR)
466 ;
467 if (res) {
468 warning("sema_wait failed: %s", os::strerror(res));
469 return NULL;
470 }
471
472 // lock the list
473 res = os::Solaris::mutex_lock(mutex());
474 assert(res == 0, "mutex_lock failed");
475
476 // remove the head of the list
477 SolarisAttachOperation* op = head();
478 if (op != NULL) {
479 set_head(op->next());
480 if (head() == NULL) {
481 set_tail(NULL);
482 }
483 }
484
485 // unlock
486 os::Solaris::mutex_unlock(mutex());
487
488 // if we got an operation when return it.
489 if (op != NULL) {
490 return op;
491 }
492 }
493 }
494
495 // Enqueue an operation
496 void SolarisAttachListener::enqueue(SolarisAttachOperation* op) {
497 // lock list
498 int res = os::Solaris::mutex_lock(mutex());
499 assert(res == 0, "mutex_lock failed");
500
501 // enqueue at tail
502 op->set_next(NULL);
503 if (head() == NULL) {
504 set_head(op);
505 } else {
506 tail()->set_next(op);
507 }
508 set_tail(op);
509
510 // wakeup the attach listener
511 RESTARTABLE(::sema_post(wakeup()), res);
512 assert(res == 0, "sema_post failed");
513
514 // unlock
515 os::Solaris::mutex_unlock(mutex());
516 }
517
518
519 // support function - writes the (entire) buffer to a socket
520 static int write_fully(int s, char* buf, int len) {
521 do {
522 int n = ::write(s, buf, len);
523 if (n == -1) {
524 if (errno != EINTR) return -1;
525 } else {
526 buf += n;
527 len -= n;
528 }
529 }
530 while (len > 0);
531 return 0;
532 }
533
534 // Complete an operation by sending the operation result and any result
535 // output to the client. At this time the socket is in blocking mode so
536 // potentially we can block if there is a lot of data and the client is
537 // non-responsive. For most operations this is a non-issue because the
538 // default send buffer is sufficient to buffer everything. In the future
539 // if there are operations that involves a very big reply then it the
540 // socket could be made non-blocking and a timeout could be used.
541
542 void SolarisAttachOperation::complete(jint res, bufferedStream* st) {
543 if (this->socket() >= 0) {
544 JavaThread* thread = JavaThread::current();
545 ThreadBlockInVM tbivm(thread);
546
547 thread->set_suspend_equivalent();
548 // cleared by handle_special_suspend_equivalent_condition() or
549 // java_suspend_self() via check_and_wait_while_suspended()
550
551 // write operation result
552 char msg[32];
553 sprintf(msg, "%d\n", res);
554 int rc = write_fully(this->socket(), msg, strlen(msg));
555
556 // write any result data
557 if (rc == 0) {
558 write_fully(this->socket(), (char*) st->base(), st->size());
559 ::shutdown(this->socket(), 2);
560 }
561
562 // close socket and we're done
563 ::close(this->socket());
564
565 // were we externally suspended while we were waiting?
566 thread->check_and_wait_while_suspended();
567 }
568 delete this;
569 }
570
571
572 // AttachListener functions
573
574 AttachOperation* AttachListener::dequeue() {
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() via check_and_wait_while_suspended()
581
582 AttachOperation* op = SolarisAttachListener::dequeue();
583
584 // were we externally suspended while we were waiting?
585 thread->check_and_wait_while_suspended();
586
587 return op;
588 }
589
590
591 // Performs initialization at vm startup
592 // For Solaris we remove any stale .java_pid file which could cause
593 // an attaching process to think we are ready to receive a door_call
594 // before we are properly initialized
595
596 void AttachListener::vm_start() {
597 char fn[PATH_MAX+1];
598 struct stat64 st;
599 int ret;
600
601 int n = snprintf(fn, sizeof(fn), "%s/.java_pid%d",
602 os::get_temp_directory(), os::current_process_id());
603 assert(n < sizeof(fn), "java_pid file name buffer overflow");
604
605 RESTARTABLE(::stat64(fn, &st), ret);
606 if (ret == 0) {
607 ret = ::unlink(fn);
608 if (ret == -1) {
609 log_debug(attach)("Failed to remove stale attach pid file at %s", fn);
610 }
611 }
612 }
613
614 int AttachListener::pd_init() {
615 JavaThread* thread = JavaThread::current();
616 ThreadBlockInVM tbivm(thread);
617
618 thread->set_suspend_equivalent();
619 // cleared by handle_special_suspend_equivalent_condition() or
620 // java_suspend_self()
621
622 int ret_code = SolarisAttachListener::init();
623
624 // were we externally suspended while we were waiting?
625 thread->check_and_wait_while_suspended();
626
627 return ret_code;
628 }
629
630 // Attach Listener is started lazily except in the case when
631 // +ReduseSignalUsage is used
632 bool AttachListener::init_at_startup() {
633 if (ReduceSignalUsage) {
634 return true;
635 } else {
636 return false;
637 }
638 }
639
640 // If the file .attach_pid<pid> exists in the working directory
641 // or /tmp then this is the trigger to start the attach mechanism
642 bool AttachListener::is_init_trigger() {
643 if (init_at_startup() || is_initialized()) {
644 return false; // initialized at startup or already initialized
645 }
646 char fn[PATH_MAX+1];
647 sprintf(fn, ".attach_pid%d", os::current_process_id());
648 int ret;
649 struct stat64 st;
650 RESTARTABLE(::stat64(fn, &st), ret);
651 if (ret == -1) {
652 log_trace(attach)("Failed to find attach file: %s, trying alternate", fn);
653 snprintf(fn, sizeof(fn), "%s/.attach_pid%d",
654 os::get_temp_directory(), os::current_process_id());
655 RESTARTABLE(::stat64(fn, &st), ret);
656 if (ret == -1) {
657 log_debug(attach)("Failed to find attach file: %s", fn);
658 }
659 }
660 if (ret == 0) {
661 // simple check to avoid starting the attach mechanism when
662 // a bogus user creates the file
663 if (st.st_uid == geteuid()) {
664 init();
665 return true;
666 }
667 }
668 return false;
669 }
670
671 // if VM aborts then detach/cleanup
672 void AttachListener::abort() {
673 listener_cleanup();
674 }
675
676 void AttachListener::pd_data_dump() {
677 os::signal_notify(SIGQUIT);
678 }
679
680 static jint enable_dprobes(AttachOperation* op, outputStream* out) {
681 const char* probe = op->arg(0);
682 if (probe == NULL || probe[0] == '\0') {
683 out->print_cr("No probe specified");
684 return JNI_ERR;
685 } else {
686 char *end;
687 long val = strtol(probe, &end, 10);
688 if (end == probe || val < 0 || val > INT_MAX) {
689 out->print_cr("invalid probe type");
690 return JNI_ERR;
691 } else {
692 int probe_typess = (int) val;
693 DTrace::enable_dprobes(probe_typess);
694 return JNI_OK;
695 }
696 }
697 }
698
699 // platform specific operations table
700 static AttachOperationFunctionInfo funcs[] = {
701 { "enabledprobes", enable_dprobes },
702 { NULL, NULL }
703 };
704
705 AttachOperationFunctionInfo* AttachListener::pd_find_operation(const char* name) {
706 int i;
707 for (i = 0; funcs[i].name != NULL; i++) {
708 if (strcmp(funcs[i].name, name) == 0) {
709 return &funcs[i];
710 }
711 }
712 return NULL;
713 }
714
715 // Solaris specific global flag set. Currently, we support only
716 // changing ExtendedDTraceProbes flag.
717 jint AttachListener::pd_set_flag(AttachOperation* op, outputStream* out) {
718 const char* name = op->arg(0);
719 assert(name != NULL, "flag name should not be null");
720 bool flag = true;
721 const char* arg1;
722 if ((arg1 = op->arg(1)) != NULL) {
723 char *end;
724 flag = (strtol(arg1, &end, 10) != 0);
725 if (arg1 == end) {
726 out->print_cr("flag value has to be an integer");
727 return JNI_ERR;
728 }
729 }
730
731 if (strcmp(name, "ExtendedDTraceProbes") == 0) {
732 DTrace::set_extended_dprobes(flag);
733 return JNI_OK;
734 }
735
736 if (strcmp(name, "DTraceMonitorProbes") == 0) {
737 DTrace::set_monitor_dprobes(flag);
738 return JNI_OK;
739 }
740
741 out->print_cr("flag '%s' cannot be changed", name);
742 return JNI_ERR;
743 }
744
745 void AttachListener::pd_detachall() {
746 DTrace::detach_all_clients();
747 }