1 /* 2 * Copyright (c) 2005, 2013, 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.hpp" 28 #include "services/attachListener.hpp" 29 #include "services/dtraceAttacher.hpp" 30 31 #include <door.h> 32 #include <string.h> 33 #include <signal.h> 34 #include <sys/types.h> 35 #include <sys/socket.h> 36 #include <sys/stat.h> 37 38 // stropts.h uses STR in stream ioctl defines 39 #undef STR 40 #include <stropts.h> 41 #undef STR 42 #define STR(a) #a 43 44 // The attach mechanism on Solaris is implemented using the Doors IPC 45 // mechanism. The first tool to attempt to attach causes the attach 46 // listener thread to startup. This thread creats a door that is 47 // associated with a function that enqueues an operation to the attach 48 // listener. The door is attached to a file in the file system so that 49 // client (tools) can locate it. To enqueue an operation to the VM the 50 // client calls through the door which invokes the enqueue function in 51 // this process. The credentials of the client are checked and if the 52 // effective uid matches this process then the operation is enqueued. 53 // When an operation completes the attach listener is required to send the 54 // operation result and any result data to the client. In this implementation 55 // the result is returned via a UNIX domain socket. A pair of connected 56 // sockets (socketpair) is created in the enqueue function and the file 57 // descriptor for one of the sockets is returned to the client as the 58 // return from the door call. The other end is retained in this process. 59 // When the operation completes the result is sent to the client and 60 // the socket is closed. 61 62 // forward reference 63 class SolarisAttachOperation; 64 65 class SolarisAttachListener: AllStatic { 66 private: 67 68 // the path to which we attach the door file descriptor 69 static char _door_path[PATH_MAX+1]; 70 static volatile bool _has_door_path; 71 72 // door descriptor returned by door_create 73 static int _door_descriptor; 74 75 static void set_door_path(char* path) { 76 if (path == NULL) { 77 _has_door_path = false; 78 } else { 79 strncpy(_door_path, path, PATH_MAX); 80 _door_path[PATH_MAX] = '\0'; // ensure it's nul terminated 81 _has_door_path = true; 82 } 83 } 84 85 static void set_door_descriptor(int dd) { _door_descriptor = dd; } 86 87 // mutex to protect operation list 88 static mutex_t _mutex; 89 90 // semaphore to wakeup listener thread 91 static sema_t _wakeup; 92 93 static mutex_t* mutex() { return &_mutex; } 94 static sema_t* wakeup() { return &_wakeup; } 95 96 // enqueued operation list 97 static SolarisAttachOperation* _head; 98 static SolarisAttachOperation* _tail; 99 100 static SolarisAttachOperation* head() { return _head; } 101 static void set_head(SolarisAttachOperation* head) { _head = head; } 102 103 static SolarisAttachOperation* tail() { return _tail; } 104 static void set_tail(SolarisAttachOperation* tail) { _tail = tail; } 105 106 // create the door 107 static int create_door(); 108 109 public: 110 enum { 111 ATTACH_PROTOCOL_VER = 1 // protocol version 112 }; 113 enum { 114 ATTACH_ERROR_BADREQUEST = 100, // error code returned by 115 ATTACH_ERROR_BADVERSION = 101, // the door call 116 ATTACH_ERROR_RESOURCE = 102, 117 ATTACH_ERROR_INTERNAL = 103, 118 ATTACH_ERROR_DENIED = 104 119 }; 120 121 // initialize the listener 122 static int init(); 123 124 static bool has_door_path() { return _has_door_path; } 125 static char* door_path() { return _door_path; } 126 static int door_descriptor() { return _door_descriptor; } 127 128 // enqueue an operation 129 static void enqueue(SolarisAttachOperation* op); 130 131 // dequeue an operation 132 static SolarisAttachOperation* dequeue(); 133 }; 134 135 136 // SolarisAttachOperation is an AttachOperation that additionally encapsulates 137 // a socket connection to the requesting client/tool. SolarisAttachOperation 138 // can additionally be held in a linked list. 139 140 class SolarisAttachOperation: public AttachOperation { 141 private: 142 friend class SolarisAttachListener; 143 144 // connection to client 145 int _socket; 146 147 // linked list support 148 SolarisAttachOperation* _next; 149 150 SolarisAttachOperation* next() { return _next; } 151 void set_next(SolarisAttachOperation* next) { _next = next; } 152 153 public: 154 void complete(jint res, bufferedStream* st); 155 156 int socket() const { return _socket; } 157 void set_socket(int s) { _socket = s; } 158 159 SolarisAttachOperation(char* name) : AttachOperation(name) { 160 set_socket(-1); 161 set_next(NULL); 162 } 163 }; 164 165 // statics 166 char SolarisAttachListener::_door_path[PATH_MAX+1]; 167 volatile bool SolarisAttachListener::_has_door_path; 168 int SolarisAttachListener::_door_descriptor = -1; 169 mutex_t SolarisAttachListener::_mutex; 170 sema_t SolarisAttachListener::_wakeup; 171 SolarisAttachOperation* SolarisAttachListener::_head = NULL; 172 SolarisAttachOperation* SolarisAttachListener::_tail = NULL; 173 174 // Supporting class to help split a buffer into individual components 175 class ArgumentIterator : public StackObj { 176 private: 177 char* _pos; 178 char* _end; 179 public: 180 ArgumentIterator(char* arg_buffer, size_t arg_size) { 181 _pos = arg_buffer; 182 _end = _pos + arg_size - 1; 183 } 184 char* next() { 185 if (*_pos == '\0') { 186 return NULL; 187 } 188 char* res = _pos; 189 char* next_pos = strchr(_pos, '\0'); 190 if (next_pos < _end) { 191 next_pos++; 192 } 193 _pos = next_pos; 194 return res; 195 } 196 }; 197 198 // Calls from the door function to check that the client credentials 199 // match this process. Returns 0 if credentials okay, otherwise -1. 200 static int check_credentials() { 201 door_cred_t cred_info; 202 203 // get client credentials 204 if (door_cred(&cred_info) == -1) { 205 return -1; // unable to get them 206 } 207 208 // get our euid/eguid (probably could cache these) 209 uid_t euid = geteuid(); 210 gid_t egid = getegid(); 211 212 // check that the effective uid/gid matches - discuss this with Jeff. 213 if (cred_info.dc_euid == euid && cred_info.dc_egid == egid) { 214 return 0; // okay 215 } else { 216 return -1; // denied 217 } 218 } 219 220 221 // Parses the argument buffer to create an AttachOperation that we should 222 // enqueue to the attach listener. 223 // The buffer is expected to be formatted as follows: 224 // <ver>0<cmd>0<arg>0<arg>0<arg>0 225 // where <ver> is the version number (must be "1"), <cmd> is the command 226 // name ("load, "datadump", ...) and <arg> is an argument. 227 // 228 static SolarisAttachOperation* create_operation(char* argp, size_t arg_size, int* err) { 229 // assume bad request until parsed 230 *err = SolarisAttachListener::ATTACH_ERROR_BADREQUEST; 231 232 if (arg_size < 2 || argp[arg_size-1] != '\0') { 233 return NULL; // no ver or not null terminated 234 } 235 236 // Use supporting class to iterate over the buffer 237 ArgumentIterator args(argp, arg_size); 238 239 // First check the protocol version 240 char* ver = args.next(); 241 if (ver == NULL) { 242 return NULL; 243 } 244 if (atoi(ver) != SolarisAttachListener::ATTACH_PROTOCOL_VER) { 245 *err = SolarisAttachListener::ATTACH_ERROR_BADVERSION; 246 return NULL; 247 } 248 249 // Get command name and create the operation 250 char* name = args.next(); 251 if (name == NULL || strlen(name) > AttachOperation::name_length_max) { 252 return NULL; 253 } 254 SolarisAttachOperation* op = new SolarisAttachOperation(name); 255 256 // Iterate over the arguments 257 for (int i=0; i<AttachOperation::arg_count_max; i++) { 258 char* arg = args.next(); 259 if (arg == NULL) { 260 op->set_arg(i, NULL); 261 } else { 262 if (strlen(arg) > AttachOperation::arg_length_max) { 263 delete op; 264 return NULL; 265 } 266 op->set_arg(i, arg); 267 } 268 } 269 270 // return operation 271 *err = 0; 272 return op; 273 } 274 275 // create special operation to indicate all clients have detached 276 static SolarisAttachOperation* create_detachall_operation() { 277 return new SolarisAttachOperation(AttachOperation::detachall_operation_name()); 278 } 279 280 // This is door function which the client executes via a door_call. 281 extern "C" { 282 static void enqueue_proc(void* cookie, char* argp, size_t arg_size, 283 door_desc_t* dt, uint_t n_desc) 284 { 285 int return_fd = -1; 286 SolarisAttachOperation* op = NULL; 287 288 // no listener 289 jint res = 0; 290 if (!AttachListener::is_initialized()) { 291 // how did we get here? 292 debug_only(warning("door_call when not enabled")); 293 res = (jint)SolarisAttachListener::ATTACH_ERROR_INTERNAL; 294 } 295 296 // check client credentials 297 if (res == 0) { 298 if (check_credentials() != 0) { 299 res = (jint)SolarisAttachListener::ATTACH_ERROR_DENIED; 300 } 301 } 302 303 // if we are stopped at ShowMessageBoxOnError then maybe we can 304 // load a diagnostic library 305 if (res == 0 && is_error_reported()) { 306 if (ShowMessageBoxOnError) { 307 // TBD - support loading of diagnostic library here 308 } 309 310 // can't enqueue operation after fatal error 311 res = (jint)SolarisAttachListener::ATTACH_ERROR_RESOURCE; 312 } 313 314 // create the operation 315 if (res == 0) { 316 int err; 317 op = create_operation(argp, arg_size, &err); 318 res = (op == NULL) ? (jint)err : 0; 319 } 320 321 // create a pair of connected sockets. Store the file descriptor 322 // for one end in the operation and enqueue the operation. The 323 // file descriptor for the other end wil be returned to the client. 324 if (res == 0) { 325 int s[2]; 326 if (socketpair(PF_UNIX, SOCK_STREAM, 0, s) < 0) { 327 delete op; 328 res = (jint)SolarisAttachListener::ATTACH_ERROR_RESOURCE; 329 } else { 330 op->set_socket(s[0]); 331 return_fd = s[1]; 332 SolarisAttachListener::enqueue(op); 333 } 334 } 335 336 // Return 0 (success) + file descriptor, or non-0 (error) 337 if (res == 0) { 338 door_desc_t desc; 339 // DOOR_RELEASE flag makes sure fd is closed after passing it to 340 // the client. See door_return(3DOOR) man page. 341 desc.d_attributes = DOOR_DESCRIPTOR | DOOR_RELEASE; 342 desc.d_data.d_desc.d_descriptor = return_fd; 343 door_return((char*)&res, sizeof(res), &desc, 1); 344 } else { 345 door_return((char*)&res, sizeof(res), NULL, 0); 346 } 347 } 348 } 349 350 // atexit hook to detach the door and remove the file 351 extern "C" { 352 static void listener_cleanup() { 353 static int cleanup_done; 354 if (!cleanup_done) { 355 cleanup_done = 1; 356 int dd = SolarisAttachListener::door_descriptor(); 357 if (dd >= 0) { 358 ::close(dd); 359 } 360 if (SolarisAttachListener::has_door_path()) { 361 char* path = SolarisAttachListener::door_path(); 362 ::fdetach(path); 363 ::unlink(path); 364 } 365 } 366 } 367 } 368 369 // Create the door 370 int SolarisAttachListener::create_door() { 371 char door_path[PATH_MAX+1]; 372 char initial_path[PATH_MAX+1]; 373 int fd, res; 374 375 // register exit function 376 ::atexit(listener_cleanup); 377 378 // create the door descriptor 379 int dd = ::door_create(enqueue_proc, NULL, 0); 380 if (dd < 0) { 381 return -1; 382 } 383 384 // create initial file to attach door descriptor 385 snprintf(door_path, sizeof(door_path), "%s/.java_pid%d", 386 os::get_temp_directory(), os::current_process_id()); 387 snprintf(initial_path, sizeof(initial_path), "%s.tmp", door_path); 388 RESTARTABLE(::creat(initial_path, S_IRUSR | S_IWUSR), fd); 389 if (fd == -1) { 390 debug_only(warning("attempt to create %s failed", initial_path)); 391 ::door_revoke(dd); 392 return -1; 393 } 394 assert(fd >= 0, "bad file descriptor"); 395 ::close(fd); 396 397 // attach the door descriptor to the file 398 if ((res = ::fattach(dd, initial_path)) == -1) { 399 // if busy then detach and try again 400 if (errno == EBUSY) { 401 ::fdetach(initial_path); 402 res = ::fattach(dd, initial_path); 403 } 404 if (res == -1) { 405 ::door_revoke(dd); 406 dd = -1; 407 } 408 } 409 410 // rename file so that clients can attach 411 if (dd >= 0) { 412 if (::rename(initial_path, door_path) == -1) { 413 ::close(dd); 414 ::fdetach(initial_path); 415 dd = -1; 416 } 417 } 418 if (dd >= 0) { 419 set_door_descriptor(dd); 420 set_door_path(door_path); 421 } else { 422 // unable to create door, attach it to file, or rename file into place 423 ::unlink(initial_path); 424 return -1; 425 } 426 427 return 0; 428 } 429 430 // Initialization - create the door, locks, and other initialization 431 int SolarisAttachListener::init() { 432 if (create_door()) { 433 return -1; 434 } 435 436 int status = os::Solaris::mutex_init(&_mutex); 437 assert_status(status==0, status, "mutex_init"); 438 439 status = ::sema_init(&_wakeup, 0, NULL, NULL); 440 assert_status(status==0, status, "sema_init"); 441 442 set_head(NULL); 443 set_tail(NULL); 444 445 return 0; 446 } 447 448 // Dequeue an operation 449 SolarisAttachOperation* SolarisAttachListener::dequeue() { 450 for (;;) { 451 int res; 452 453 // wait for somebody to enqueue something 454 while ((res = ::sema_wait(wakeup())) == EINTR) 455 ; 456 if (res) { 457 warning("sema_wait failed: %s", strerror(res)); 458 return NULL; 459 } 460 461 // lock the list 462 res = os::Solaris::mutex_lock(mutex()); 463 assert(res == 0, "mutex_lock failed"); 464 465 // remove the head of the list 466 SolarisAttachOperation* op = head(); 467 if (op != NULL) { 468 set_head(op->next()); 469 if (head() == NULL) { 470 set_tail(NULL); 471 } 472 } 473 474 // unlock 475 os::Solaris::mutex_unlock(mutex()); 476 477 // if we got an operation when return it. 478 if (op != NULL) { 479 return op; 480 } 481 } 482 } 483 484 // Enqueue an operation 485 void SolarisAttachListener::enqueue(SolarisAttachOperation* op) { 486 // lock list 487 int res = os::Solaris::mutex_lock(mutex()); 488 assert(res == 0, "mutex_lock failed"); 489 490 // enqueue at tail 491 op->set_next(NULL); 492 if (head() == NULL) { 493 set_head(op); 494 } else { 495 tail()->set_next(op); 496 } 497 set_tail(op); 498 499 // wakeup the attach listener 500 RESTARTABLE(::sema_post(wakeup()), res); 501 assert(res == 0, "sema_post failed"); 502 503 // unlock 504 os::Solaris::mutex_unlock(mutex()); 505 } 506 507 508 // support function - writes the (entire) buffer to a socket 509 static int write_fully(int s, char* buf, int len) { 510 do { 511 int n = ::write(s, buf, len); 512 if (n == -1) { 513 if (errno != EINTR) return -1; 514 } else { 515 buf += n; 516 len -= n; 517 } 518 } 519 while (len > 0); 520 return 0; 521 } 522 523 // Complete an operation by sending the operation result and any result 524 // output to the client. At this time the socket is in blocking mode so 525 // potentially we can block if there is a lot of data and the client is 526 // non-responsive. For most operations this is a non-issue because the 527 // default send buffer is sufficient to buffer everything. In the future 528 // if there are operations that involves a very big reply then it the 529 // socket could be made non-blocking and a timeout could be used. 530 531 void SolarisAttachOperation::complete(jint res, bufferedStream* st) { 532 if (this->socket() >= 0) { 533 JavaThread* thread = JavaThread::current(); 534 ThreadBlockInVM tbivm(thread); 535 536 thread->set_suspend_equivalent(); 537 // cleared by handle_special_suspend_equivalent_condition() or 538 // java_suspend_self() via check_and_wait_while_suspended() 539 540 // write operation result 541 char msg[32]; 542 sprintf(msg, "%d\n", res); 543 int rc = write_fully(this->socket(), msg, strlen(msg)); 544 545 // write any result data 546 if (rc == 0) { 547 write_fully(this->socket(), (char*) st->base(), st->size()); 548 ::shutdown(this->socket(), 2); 549 } 550 551 // close socket and we're done 552 ::close(this->socket()); 553 554 // were we externally suspended while we were waiting? 555 thread->check_and_wait_while_suspended(); 556 } 557 delete this; 558 } 559 560 561 // AttachListener functions 562 563 AttachOperation* AttachListener::dequeue() { 564 JavaThread* thread = JavaThread::current(); 565 ThreadBlockInVM tbivm(thread); 566 567 thread->set_suspend_equivalent(); 568 // cleared by handle_special_suspend_equivalent_condition() or 569 // java_suspend_self() via check_and_wait_while_suspended() 570 571 AttachOperation* op = SolarisAttachListener::dequeue(); 572 573 // were we externally suspended while we were waiting? 574 thread->check_and_wait_while_suspended(); 575 576 return op; 577 } 578 579 580 // Performs initialization at vm startup 581 // For Solaris we remove any stale .java_pid file which could cause 582 // an attaching process to think we are ready to receive a door_call 583 // before we are properly initialized 584 585 void AttachListener::vm_start() { 586 char fn[PATH_MAX+1]; 587 struct stat64 st; 588 int ret; 589 590 int n = snprintf(fn, sizeof(fn), "%s/.java_pid%d", 591 os::get_temp_directory(), os::current_process_id()); 592 assert(n < sizeof(fn), "java_pid file name buffer overflow"); 593 594 RESTARTABLE(::stat64(fn, &st), ret); 595 if (ret == 0) { 596 ret = ::unlink(fn); 597 if (ret == -1) { 598 debug_only(warning("failed to remove stale attach pid file at %s", fn)); 599 } 600 } 601 } 602 603 int AttachListener::pd_init() { 604 JavaThread* thread = JavaThread::current(); 605 ThreadBlockInVM tbivm(thread); 606 607 thread->set_suspend_equivalent(); 608 // cleared by handle_special_suspend_equivalent_condition() or 609 // java_suspend_self() 610 611 int ret_code = SolarisAttachListener::init(); 612 613 // were we externally suspended while we were waiting? 614 thread->check_and_wait_while_suspended(); 615 616 return ret_code; 617 } 618 619 // Attach Listener is started lazily except in the case when 620 // +ReduseSignalUsage is used 621 bool AttachListener::init_at_startup() { 622 if (ReduceSignalUsage) { 623 return true; 624 } else { 625 return false; 626 } 627 } 628 629 // If the file .attach_pid<pid> exists in the working directory 630 // or /tmp then this is the trigger to start the attach mechanism 631 bool AttachListener::is_init_trigger() { 632 if (init_at_startup() || is_initialized()) { 633 return false; // initialized at startup or already initialized 634 } 635 char fn[PATH_MAX+1]; 636 sprintf(fn, ".attach_pid%d", os::current_process_id()); 637 int ret; 638 struct stat64 st; 639 RESTARTABLE(::stat64(fn, &st), ret); 640 if (ret == -1) { 641 snprintf(fn, sizeof(fn), "%s/.attach_pid%d", 642 os::get_temp_directory(), os::current_process_id()); 643 RESTARTABLE(::stat64(fn, &st), ret); 644 } 645 if (ret == 0) { 646 // simple check to avoid starting the attach mechanism when 647 // a bogus user creates the file 648 if (st.st_uid == geteuid()) { 649 init(); 650 return true; 651 } 652 } 653 return false; 654 } 655 656 // if VM aborts then detach/cleanup 657 void AttachListener::abort() { 658 listener_cleanup(); 659 } 660 661 void AttachListener::pd_data_dump() { 662 os::signal_notify(SIGQUIT); 663 } 664 665 static jint enable_dprobes(AttachOperation* op, outputStream* out) { 666 const char* probe = op->arg(0); 667 if (probe == NULL || probe[0] == '\0') { 668 out->print_cr("No probe specified"); 669 return JNI_ERR; 670 } else { 671 errno = 0; 672 int probe_typess = (int)strtol(probe, (char **)NULL, 10); 673 if (errno) { 674 out->print_cr("invalid probe type"); 675 return JNI_ERR; 676 } else { 677 DTrace::enable_dprobes(probe_typess); 678 return JNI_OK; 679 } 680 } 681 } 682 683 // platform specific operations table 684 static AttachOperationFunctionInfo funcs[] = { 685 { "enabledprobes", enable_dprobes }, 686 { NULL, NULL } 687 }; 688 689 AttachOperationFunctionInfo* AttachListener::pd_find_operation(const char* name) { 690 int i; 691 for (i = 0; funcs[i].name != NULL; i++) { 692 if (strcmp(funcs[i].name, name) == 0) { 693 return &funcs[i]; 694 } 695 } 696 return NULL; 697 } 698 699 // Solaris specific global flag set. Currently, we support only 700 // changing ExtendedDTraceProbes flag. 701 jint AttachListener::pd_set_flag(AttachOperation* op, outputStream* out) { 702 const char* name = op->arg(0); 703 assert(name != NULL, "flag name should not be null"); 704 bool flag = true; 705 const char* arg1; 706 if ((arg1 = op->arg(1)) != NULL) { 707 errno = 0; 708 flag = (strtol(arg1, (char **)NULL, 10) != 0); 709 if (errno) { 710 out->print_cr("flag value has to be an integer"); 711 return JNI_ERR; 712 } 713 } 714 715 if (strcmp(name, "ExtendedDTraceProbes") == 0) { 716 DTrace::set_extended_dprobes(flag); 717 return JNI_OK; 718 } 719 720 if (strcmp(name, "DTraceMonitorProbes") == 0) { 721 DTrace::set_monitor_dprobes(flag); 722 return JNI_OK; 723 } 724 725 out->print_cr("flag '%s' cannot be changed", name); 726 return JNI_ERR; 727 } 728 729 void AttachListener::pd_detachall() { 730 DTrace::detach_all_clients(); 731 }