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 }