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 }