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 "logging/log.hpp"
27 #include "runtime/interfaceSupport.inline.hpp"
28 #include "runtime/os.inline.hpp"
29 #include "services/attachListener.hpp"
30 #include "services/dtraceAttacher.hpp"
31 #include "utilities/vmError.hpp"
32
33 #include <door.h>
34 #include <limits.h>
35 #include <string.h>
36 #include <signal.h>
37 #include <sys/types.h>
38 #include <sys/socket.h>
39 #include <sys/stat.h>
40
41 // stropts.h uses STR in stream ioctl defines
42 #undef STR
43 #include <stropts.h>
44 #undef STR
45 #define STR(a) #a
46
47 // The attach mechanism on Solaris is implemented using the Doors IPC
48 // mechanism. The first tool to attempt to attach causes the attach
49 // listener thread to startup. This thread creats a door that is
50 // associated with a function that enqueues an operation to the attach
51 // listener. The door is attached to a file in the file system so that
52 // client (tools) can locate it. To enqueue an operation to the VM the
53 // client calls through the door which invokes the enqueue function in
54 // this process. The credentials of the client are checked and if the
55 // effective uid matches this process then the operation is enqueued.
56 // When an operation completes the attach listener is required to send the
57 // operation result and any result data to the client. In this implementation
58 // the result is returned via a UNIX domain socket. A pair of connected
59 // sockets (socketpair) is created in the enqueue function and the file
60 // descriptor for one of the sockets is returned to the client as the
61 // return from the door call. The other end is retained in this process.
62 // When the operation completes the result is sent to the client and
63 // the socket is closed.
64
65 // forward reference
66 class SolarisAttachOperation;
67
68 class SolarisAttachListener: AllStatic {
69 private:
70
71 // the path to which we attach the door file descriptor
72 static char _door_path[PATH_MAX+1];
73 static volatile bool _has_door_path;
74
75 // door descriptor returned by door_create
76 static int _door_descriptor;
77
78 static void set_door_path(char* path) {
79 if (path == NULL) {
80 _has_door_path = false;
81 } else {
82 strncpy(_door_path, path, PATH_MAX);
83 _door_path[PATH_MAX] = '\0'; // ensure it's nul terminated
84 _has_door_path = true;
85 }
86 }
87
88 static void set_door_descriptor(int dd) { _door_descriptor = dd; }
89
90 // mutex to protect operation list
91 static mutex_t _mutex;
92
93 // semaphore to wakeup listener thread
94 static sema_t _wakeup;
95
96 static mutex_t* mutex() { return &_mutex; }
97 static sema_t* wakeup() { return &_wakeup; }
98
99 // enqueued operation list
100 static SolarisAttachOperation* _head;
101 static SolarisAttachOperation* _tail;
102
103 static SolarisAttachOperation* head() { return _head; }
104 static void set_head(SolarisAttachOperation* head) { _head = head; }
105
106 static SolarisAttachOperation* tail() { return _tail; }
107 static void set_tail(SolarisAttachOperation* tail) { _tail = tail; }
108
109 // create the door
110 static int create_door();
111
112 public:
113 enum {
114 ATTACH_PROTOCOL_VER = 1 // protocol version
115 };
116 enum {
117 ATTACH_ERROR_BADREQUEST = 100, // error code returned by
118 ATTACH_ERROR_BADVERSION = 101, // the door call
119 ATTACH_ERROR_RESOURCE = 102,
120 ATTACH_ERROR_INTERNAL = 103,
121 ATTACH_ERROR_DENIED = 104
122 };
123
124 // initialize the listener
125 static int init();
126
127 static bool has_door_path() { return _has_door_path; }
128 static char* door_path() { return _door_path; }
129 static int door_descriptor() { return _door_descriptor; }
130
131 // enqueue an operation
132 static void enqueue(SolarisAttachOperation* op);
133
134 // dequeue an operation
135 static SolarisAttachOperation* dequeue();
136 };
137
138
139 // SolarisAttachOperation is an AttachOperation that additionally encapsulates
140 // a socket connection to the requesting client/tool. SolarisAttachOperation
141 // can additionally be held in a linked list.
142
143 class SolarisAttachOperation: public AttachOperation {
144 private:
145 friend class SolarisAttachListener;
146
147 // connection to client
148 int _socket;
149
150 // linked list support
151 SolarisAttachOperation* _next;
152
153 SolarisAttachOperation* next() { return _next; }
154 void set_next(SolarisAttachOperation* next) { _next = next; }
155
156 public:
157 void complete(jint res, bufferedStream* st);
158
159 int socket() const { return _socket; }
160 void set_socket(int s) { _socket = s; }
161
162 SolarisAttachOperation(char* name) : AttachOperation(name) {
163 set_socket(-1);
164 set_next(NULL);
165 }
166 };
167
168 // statics
169 char SolarisAttachListener::_door_path[PATH_MAX+1];
170 volatile bool SolarisAttachListener::_has_door_path;
171 int SolarisAttachListener::_door_descriptor = -1;
172 mutex_t SolarisAttachListener::_mutex;
173 sema_t SolarisAttachListener::_wakeup;
174 SolarisAttachOperation* SolarisAttachListener::_head = NULL;
175 SolarisAttachOperation* SolarisAttachListener::_tail = NULL;
176
177 // Supporting class to help split a buffer into individual components
178 class ArgumentIterator : public StackObj {
179 private:
180 char* _pos;
181 char* _end;
182 public:
183 ArgumentIterator(char* arg_buffer, size_t arg_size) {
184 _pos = arg_buffer;
185 _end = _pos + arg_size - 1;
186 }
187 char* next() {
188 if (*_pos == '\0') {
189 return NULL;
190 }
191 char* res = _pos;
192 char* next_pos = strchr(_pos, '\0');
193 if (next_pos < _end) {
194 next_pos++;
195 }
196 _pos = next_pos;
197 return res;
198 }
199 };
200
201 // Calls from the door function to check that the client credentials
202 // match this process. Returns 0 if credentials okay, otherwise -1.
203 static int check_credentials() {
204 ucred_t *cred_info = NULL;
205 int ret = -1; // deny by default
206
207 // get client credentials
208 if (door_ucred(&cred_info) == -1) {
209 return -1; // unable to get them, deny
210 }
211
212 // get our euid/eguid (probably could cache these)
213 uid_t euid = geteuid();
214 gid_t egid = getegid();
215
216 // get euid/egid from ucred_free
217 uid_t ucred_euid = ucred_geteuid(cred_info);
218 gid_t ucred_egid = ucred_getegid(cred_info);
219
220 // check that the effective uid/gid matches
221 if (ucred_euid == euid && ucred_egid == egid) {
222 ret = 0; // allow
223 }
224
225 ucred_free(cred_info);
226 return ret;
227 }
228
229
230 // Parses the argument buffer to create an AttachOperation that we should
231 // enqueue to the attach listener.
232 // The buffer is expected to be formatted as follows:
233 // <ver>0<cmd>0<arg>0<arg>0<arg>0
234 // where <ver> is the version number (must be "1"), <cmd> is the command
235 // name ("load, "datadump", ...) and <arg> is an argument.
236 //
237 static SolarisAttachOperation* create_operation(char* argp, size_t arg_size, int* err) {
238 // assume bad request until parsed
239 *err = SolarisAttachListener::ATTACH_ERROR_BADREQUEST;
240
241 if (arg_size < 2 || argp[arg_size-1] != '\0') {
242 return NULL; // no ver or not null terminated
243 }
244
245 // Use supporting class to iterate over the buffer
246 ArgumentIterator args(argp, arg_size);
247
248 // First check the protocol version
249 char* ver = args.next();
250 if (ver == NULL) {
251 return NULL;
252 }
253 if (atoi(ver) != SolarisAttachListener::ATTACH_PROTOCOL_VER) {
254 *err = SolarisAttachListener::ATTACH_ERROR_BADVERSION;
255 return NULL;
256 }
257
258 // Get command name and create the operation
259 char* name = args.next();
260 if (name == NULL || strlen(name) > AttachOperation::name_length_max) {
261 return NULL;
262 }
263 SolarisAttachOperation* op = new SolarisAttachOperation(name);
264
265 // Iterate over the arguments
266 for (int i=0; i<AttachOperation::arg_count_max; i++) {
267 char* arg = args.next();
268 if (arg == NULL) {
269 op->set_arg(i, NULL);
270 } else {
271 if (strlen(arg) > AttachOperation::arg_length_max) {
272 delete op;
273 return NULL;
274 }
275 op->set_arg(i, arg);
276 }
277 }
278
279 // return operation
280 *err = 0;
281 return op;
282 }
283
284 // create special operation to indicate all clients have detached
285 static SolarisAttachOperation* create_detachall_operation() {
286 return new SolarisAttachOperation(AttachOperation::detachall_operation_name());
287 }
288
289 // This is door function which the client executes via a door_call.
290 extern "C" {
291 static void enqueue_proc(void* cookie, char* argp, size_t arg_size,
292 door_desc_t* dt, uint_t n_desc)
293 {
294 int return_fd = -1;
295 SolarisAttachOperation* op = NULL;
296
297 // no listener
298 jint res = 0;
299 if (!AttachListener::is_initialized()) {
300 // how did we get here?
301 debug_only(warning("door_call when not enabled"));
302 res = (jint)SolarisAttachListener::ATTACH_ERROR_INTERNAL;
303 }
304
305 // check client credentials
306 if (res == 0) {
307 if (check_credentials() != 0) {
308 res = (jint)SolarisAttachListener::ATTACH_ERROR_DENIED;
309 }
310 }
311
312 // if we are stopped at ShowMessageBoxOnError then maybe we can
313 // load a diagnostic library
314 if (res == 0 && VMError::is_error_reported()) {
315 if (ShowMessageBoxOnError) {
316 // TBD - support loading of diagnostic library here
317 }
318
319 // can't enqueue operation after fatal error
320 res = (jint)SolarisAttachListener::ATTACH_ERROR_RESOURCE;
321 }
322
323 // create the operation
324 if (res == 0) {
325 int err;
326 op = create_operation(argp, arg_size, &err);
327 res = (op == NULL) ? (jint)err : 0;
328 }
329
330 // create a pair of connected sockets. Store the file descriptor
331 // for one end in the operation and enqueue the operation. The
332 // file descriptor for the other end wil be returned to the client.
333 if (res == 0) {
334 int s[2];
335 if (socketpair(PF_UNIX, SOCK_STREAM, 0, s) < 0) {
336 delete op;
337 res = (jint)SolarisAttachListener::ATTACH_ERROR_RESOURCE;
338 } else {
339 op->set_socket(s[0]);
340 return_fd = s[1];
341 SolarisAttachListener::enqueue(op);
342 }
343 }
344
345 // Return 0 (success) + file descriptor, or non-0 (error)
346 if (res == 0) {
347 door_desc_t desc;
348 // DOOR_RELEASE flag makes sure fd is closed after passing it to
349 // the client. See door_return(3DOOR) man page.
350 desc.d_attributes = DOOR_DESCRIPTOR | DOOR_RELEASE;
351 desc.d_data.d_desc.d_descriptor = return_fd;
352 door_return((char*)&res, sizeof(res), &desc, 1);
353 } else {
354 door_return((char*)&res, sizeof(res), NULL, 0);
355 }
356 }
357 }
358
359 // atexit hook to detach the door and remove the file
360 extern "C" {
361 static void listener_cleanup() {
362 static int cleanup_done;
363 if (!cleanup_done) {
364 cleanup_done = 1;
365 int dd = SolarisAttachListener::door_descriptor();
366 if (dd >= 0) {
367 ::close(dd);
368 }
369 if (SolarisAttachListener::has_door_path()) {
370 char* path = SolarisAttachListener::door_path();
371 ::fdetach(path);
372 ::unlink(path);
373 }
374 }
375 }
376 }
377
378 // Create the door
379 int SolarisAttachListener::create_door() {
380 char door_path[PATH_MAX+1];
381 char initial_path[PATH_MAX+1];
382 int fd, res;
383
384 // register exit function
385 ::atexit(listener_cleanup);
386
387 // create the door descriptor
388 int dd = ::door_create(enqueue_proc, NULL, 0);
389 if (dd < 0) {
390 return -1;
391 }
392
393 // create initial file to attach door descriptor
394 snprintf(door_path, sizeof(door_path), "%s/.java_pid%d",
395 os::get_temp_directory(), os::current_process_id());
396 snprintf(initial_path, sizeof(initial_path), "%s.tmp", door_path);
397 RESTARTABLE(::creat(initial_path, S_IRUSR | S_IWUSR), fd);
398 if (fd == -1) {
399 log_debug(attach)("attempt to create door file %s failed (%d)", initial_path, errno);
400 ::door_revoke(dd);
401 return -1;
402 }
403 assert(fd >= 0, "bad file descriptor");
404 ::close(fd);
405
406 // attach the door descriptor to the file
407 if ((res = ::fattach(dd, initial_path)) == -1) {
408 // if busy then detach and try again
409 if (errno == EBUSY) {
410 ::fdetach(initial_path);
411 res = ::fattach(dd, initial_path);
412 }
413 if (res == -1) {
414 log_debug(attach)("unable to create door - fattach failed (%d)", errno);
415 ::door_revoke(dd);
416 dd = -1;
417 }
418 }
419
420 // rename file so that clients can attach
421 if (dd >= 0) {
422 if (::rename(initial_path, door_path) == -1) {
423 ::close(dd);
424 ::fdetach(initial_path);
425 log_debug(attach)("unable to create door - rename %s to %s failed (%d)", errno);
426 dd = -1;
427 }
428 }
429 if (dd >= 0) {
430 set_door_descriptor(dd);
431 set_door_path(door_path);
432 log_trace(attach)("door file %s created succesfully", door_path);
433 } else {
434 // unable to create door, attach it to file, or rename file into place
435 ::unlink(initial_path);
436 return -1;
437 }
438
439 return 0;
440 }
441
442 // Initialization - create the door, locks, and other initialization
443 int SolarisAttachListener::init() {
444 if (create_door()) {
445 return -1;
446 }
447
448 int status = os::Solaris::mutex_init(&_mutex);
449 assert_status(status==0, status, "mutex_init");
450
451 status = ::sema_init(&_wakeup, 0, NULL, NULL);
452 assert_status(status==0, status, "sema_init");
453
454 set_head(NULL);
455 set_tail(NULL);
456
457 return 0;
458 }
459
460 // Dequeue an operation
461 SolarisAttachOperation* SolarisAttachListener::dequeue() {
462 for (;;) {
463 int res;
464
465 // wait for somebody to enqueue something
466 while ((res = ::sema_wait(wakeup())) == EINTR)
467 ;
468 if (res) {
469 warning("sema_wait failed: %s", os::strerror(res));
470 return NULL;
471 }
472
473 // lock the list
474 res = os::Solaris::mutex_lock(mutex());
475 assert(res == 0, "mutex_lock failed");
476
477 // remove the head of the list
478 SolarisAttachOperation* op = head();
479 if (op != NULL) {
480 set_head(op->next());
481 if (head() == NULL) {
482 set_tail(NULL);
483 }
484 }
485
486 // unlock
487 os::Solaris::mutex_unlock(mutex());
488
489 // if we got an operation when return it.
490 if (op != NULL) {
491 return op;
492 }
493 }
494 }
495
496 // Enqueue an operation
497 void SolarisAttachListener::enqueue(SolarisAttachOperation* op) {
498 // lock list
499 int res = os::Solaris::mutex_lock(mutex());
500 assert(res == 0, "mutex_lock failed");
501
502 // enqueue at tail
503 op->set_next(NULL);
504 if (head() == NULL) {
505 set_head(op);
506 } else {
507 tail()->set_next(op);
508 }
509 set_tail(op);
510
511 // wakeup the attach listener
512 RESTARTABLE(::sema_post(wakeup()), res);
513 assert(res == 0, "sema_post failed");
514
515 // unlock
516 os::Solaris::mutex_unlock(mutex());
517 }
518
519
520 // support function - writes the (entire) buffer to a socket
521 static int write_fully(int s, char* buf, int len) {
522 do {
523 int n = ::write(s, buf, len);
524 if (n == -1) {
525 if (errno != EINTR) return -1;
526 } else {
527 buf += n;
528 len -= n;
529 }
530 }
531 while (len > 0);
532 return 0;
533 }
534
535 // Complete an operation by sending the operation result and any result
536 // output to the client. At this time the socket is in blocking mode so
537 // potentially we can block if there is a lot of data and the client is
538 // non-responsive. For most operations this is a non-issue because the
539 // default send buffer is sufficient to buffer everything. In the future
540 // if there are operations that involves a very big reply then it the
541 // socket could be made non-blocking and a timeout could be used.
542
543 void SolarisAttachOperation::complete(jint res, bufferedStream* st) {
544 if (this->socket() >= 0) {
545 JavaThread* thread = JavaThread::current();
546 ThreadBlockInVM tbivm(thread);
547
548 thread->set_suspend_equivalent();
549 // cleared by handle_special_suspend_equivalent_condition() or
550 // java_suspend_self() via check_and_wait_while_suspended()
551
552 // write operation result
553 char msg[32];
554 sprintf(msg, "%d\n", res);
555 int rc = write_fully(this->socket(), msg, strlen(msg));
556
557 // write any result data
558 if (rc == 0) {
559 write_fully(this->socket(), (char*) st->base(), st->size());
560 ::shutdown(this->socket(), 2);
561 }
562
563 // close socket and we're done
564 ::close(this->socket());
565
566 // were we externally suspended while we were waiting?
567 thread->check_and_wait_while_suspended();
568 }
569 delete this;
570 }
571
572
573 // AttachListener functions
574
575 AttachOperation* AttachListener::dequeue() {
576 JavaThread* thread = JavaThread::current();
577 ThreadBlockInVM tbivm(thread);
578
579 thread->set_suspend_equivalent();
580 // cleared by handle_special_suspend_equivalent_condition() or
581 // java_suspend_self() via check_and_wait_while_suspended()
582
583 AttachOperation* op = SolarisAttachListener::dequeue();
584
585 // were we externally suspended while we were waiting?
586 thread->check_and_wait_while_suspended();
587
588 return op;
589 }
590
591
592 // Performs initialization at vm startup
593 // For Solaris we remove any stale .java_pid file which could cause
594 // an attaching process to think we are ready to receive a door_call
595 // before we are properly initialized
596
597 void AttachListener::vm_start() {
598 char fn[PATH_MAX+1];
599 struct stat64 st;
600 int ret;
601
602 int n = snprintf(fn, sizeof(fn), "%s/.java_pid%d",
603 os::get_temp_directory(), os::current_process_id());
604 assert(n < sizeof(fn), "java_pid file name buffer overflow");
605
606 RESTARTABLE(::stat64(fn, &st), ret);
607 if (ret == 0) {
608 ret = ::unlink(fn);
609 if (ret == -1) {
610 log_debug(attach)("Failed to remove stale attach pid file at %s", fn);
611 }
612 }
613 }
614
615 int AttachListener::pd_init() {
616 JavaThread* thread = JavaThread::current();
617 ThreadBlockInVM tbivm(thread);
618
619 thread->set_suspend_equivalent();
620 // cleared by handle_special_suspend_equivalent_condition() or
621 // java_suspend_self()
622
623 int ret_code = SolarisAttachListener::init();
624
625 // were we externally suspended while we were waiting?
626 thread->check_and_wait_while_suspended();
627
628 return ret_code;
629 }
630
631 // Attach Listener is started lazily except in the case when
632 // +ReduseSignalUsage is used
633 bool AttachListener::init_at_startup() {
634 if (ReduceSignalUsage) {
635 return true;
636 } else {
637 return false;
638 }
639 }
640
641 // If the file .attach_pid<pid> exists in the working directory
642 // or /tmp then this is the trigger to start the attach mechanism
643 bool AttachListener::is_init_trigger() {
644 if (init_at_startup() || is_initialized()) {
645 return false; // initialized at startup or already initialized
646 }
647 char fn[PATH_MAX+1];
648 sprintf(fn, ".attach_pid%d", os::current_process_id());
649 int ret;
650 struct stat64 st;
651 RESTARTABLE(::stat64(fn, &st), ret);
652 if (ret == -1) {
653 log_trace(attach)("Failed to find attach file: %s, trying alternate", fn);
654 snprintf(fn, sizeof(fn), "%s/.attach_pid%d",
655 os::get_temp_directory(), os::current_process_id());
656 RESTARTABLE(::stat64(fn, &st), ret);
657 if (ret == -1) {
658 log_debug(attach)("Failed to find attach file: %s", fn);
659 }
660 }
661 if (ret == 0) {
662 // simple check to avoid starting the attach mechanism when
663 // a bogus user creates the file
664 if (st.st_uid == geteuid()) {
665 init();
666 return true;
667 }
668 }
669 return false;
670 }
671
672 // if VM aborts then detach/cleanup
673 void AttachListener::abort() {
674 listener_cleanup();
675 }
676
677 void AttachListener::pd_data_dump() {
678 os::signal_notify(SIGQUIT);
679 }
680
681 static jint enable_dprobes(AttachOperation* op, outputStream* out) {
682 const char* probe = op->arg(0);
683 if (probe == NULL || probe[0] == '\0') {
684 out->print_cr("No probe specified");
685 return JNI_ERR;
686 } else {
687 char *end;
688 long val = strtol(probe, &end, 10);
689 if (end == probe || val < 0 || val > INT_MAX) {
690 out->print_cr("invalid probe type");
691 return JNI_ERR;
692 } else {
693 int probe_typess = (int) val;
694 DTrace::enable_dprobes(probe_typess);
695 return JNI_OK;
696 }
697 }
698 }
699
700 // platform specific operations table
701 static AttachOperationFunctionInfo funcs[] = {
702 { "enabledprobes", enable_dprobes },
703 { NULL, NULL }
704 };
705
706 AttachOperationFunctionInfo* AttachListener::pd_find_operation(const char* name) {
707 int i;
708 for (i = 0; funcs[i].name != NULL; i++) {
709 if (strcmp(funcs[i].name, name) == 0) {
710 return &funcs[i];
711 }
712 }
713 return NULL;
714 }
715
716 // Solaris specific global flag set. Currently, we support only
717 // changing ExtendedDTraceProbes flag.
718 jint AttachListener::pd_set_flag(AttachOperation* op, outputStream* out) {
719 const char* name = op->arg(0);
720 assert(name != NULL, "flag name should not be null");
721 bool flag = true;
722 const char* arg1;
723 if ((arg1 = op->arg(1)) != NULL) {
724 char *end;
725 flag = (strtol(arg1, &end, 10) != 0);
726 if (arg1 == end) {
727 out->print_cr("flag value has to be an integer");
728 return JNI_ERR;
729 }
730 }
731
732 if (strcmp(name, "ExtendedDTraceProbes") == 0) {
733 DTrace::set_extended_dprobes(flag);
734 return JNI_OK;
735 }
736
737 if (strcmp(name, "DTraceMonitorProbes") == 0) {
738 DTrace::set_monitor_dprobes(flag);
739 return JNI_OK;
740 }
741
742 out->print_cr("flag '%s' cannot be changed", name);
743 return JNI_ERR;
744 }
745
746 void AttachListener::pd_detachall() {
747 DTrace::detach_all_clients();
748 }