perfMemory_bsd.cpp revision 10627:1537c752a7f5
1/* 2 * Copyright (c) 2001, 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 "classfile/vmSymbols.hpp" 27#include "memory/allocation.inline.hpp" 28#include "memory/resourceArea.hpp" 29#include "oops/oop.inline.hpp" 30#include "os_bsd.inline.hpp" 31#include "runtime/handles.inline.hpp" 32#include "runtime/os.hpp" 33#include "runtime/perfMemory.hpp" 34#include "services/memTracker.hpp" 35#include "utilities/exceptions.hpp" 36 37// put OS-includes here 38# include <sys/types.h> 39# include <sys/mman.h> 40# include <errno.h> 41# include <stdio.h> 42# include <unistd.h> 43# include <sys/stat.h> 44# include <signal.h> 45# include <pwd.h> 46 47static char* backing_store_file_name = NULL; // name of the backing store 48 // file, if successfully created. 49 50// Standard Memory Implementation Details 51 52// create the PerfData memory region in standard memory. 53// 54static char* create_standard_memory(size_t size) { 55 56 // allocate an aligned chuck of memory 57 char* mapAddress = os::reserve_memory(size); 58 59 if (mapAddress == NULL) { 60 return NULL; 61 } 62 63 // commit memory 64 if (!os::commit_memory(mapAddress, size, !ExecMem)) { 65 if (PrintMiscellaneous && Verbose) { 66 warning("Could not commit PerfData memory\n"); 67 } 68 os::release_memory(mapAddress, size); 69 return NULL; 70 } 71 72 return mapAddress; 73} 74 75// delete the PerfData memory region 76// 77static void delete_standard_memory(char* addr, size_t size) { 78 79 // there are no persistent external resources to cleanup for standard 80 // memory. since DestroyJavaVM does not support unloading of the JVM, 81 // cleanup of the memory resource is not performed. The memory will be 82 // reclaimed by the OS upon termination of the process. 83 // 84 return; 85} 86 87// save the specified memory region to the given file 88// 89// Note: this function might be called from signal handler (by os::abort()), 90// don't allocate heap memory. 91// 92static void save_memory_to_file(char* addr, size_t size) { 93 94 const char* destfile = PerfMemory::get_perfdata_file_path(); 95 assert(destfile[0] != '\0', "invalid PerfData file path"); 96 97 int result; 98 99 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), 100 result);; 101 if (result == OS_ERR) { 102 if (PrintMiscellaneous && Verbose) { 103 warning("Could not create Perfdata save file: %s: %s\n", 104 destfile, os::strerror(errno)); 105 } 106 } else { 107 int fd = result; 108 109 for (size_t remaining = size; remaining > 0;) { 110 111 RESTARTABLE(::write(fd, addr, remaining), result); 112 if (result == OS_ERR) { 113 if (PrintMiscellaneous && Verbose) { 114 warning("Could not write Perfdata save file: %s: %s\n", 115 destfile, os::strerror(errno)); 116 } 117 break; 118 } 119 120 remaining -= (size_t)result; 121 addr += result; 122 } 123 124 result = ::close(fd); 125 if (PrintMiscellaneous && Verbose) { 126 if (result == OS_ERR) { 127 warning("Could not close %s: %s\n", destfile, os::strerror(errno)); 128 } 129 } 130 } 131 FREE_C_HEAP_ARRAY(char, destfile); 132} 133 134 135// Shared Memory Implementation Details 136 137// Note: the solaris and bsd shared memory implementation uses the mmap 138// interface with a backing store file to implement named shared memory. 139// Using the file system as the name space for shared memory allows a 140// common name space to be supported across a variety of platforms. It 141// also provides a name space that Java applications can deal with through 142// simple file apis. 143// 144// The solaris and bsd implementations store the backing store file in 145// a user specific temporary directory located in the /tmp file system, 146// which is always a local file system and is sometimes a RAM based file 147// system. 148 149// return the user specific temporary directory name. 150// 151// the caller is expected to free the allocated memory. 152// 153static char* get_user_tmp_dir(const char* user) { 154 155 const char* tmpdir = os::get_temp_directory(); 156 const char* perfdir = PERFDATA_NAME; 157 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3; 158 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 159 160 // construct the path name to user specific tmp directory 161 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user); 162 163 return dirname; 164} 165 166// convert the given file name into a process id. if the file 167// does not meet the file naming constraints, return 0. 168// 169static pid_t filename_to_pid(const char* filename) { 170 171 // a filename that doesn't begin with a digit is not a 172 // candidate for conversion. 173 // 174 if (!isdigit(*filename)) { 175 return 0; 176 } 177 178 // check if file name can be converted to an integer without 179 // any leftover characters. 180 // 181 char* remainder = NULL; 182 errno = 0; 183 pid_t pid = (pid_t)strtol(filename, &remainder, 10); 184 185 if (errno != 0) { 186 return 0; 187 } 188 189 // check for left over characters. If any, then the filename is 190 // not a candidate for conversion. 191 // 192 if (remainder != NULL && *remainder != '\0') { 193 return 0; 194 } 195 196 // successful conversion, return the pid 197 return pid; 198} 199 200 201// Check if the given statbuf is considered a secure directory for 202// the backing store files. Returns true if the directory is considered 203// a secure location. Returns false if the statbuf is a symbolic link or 204// if an error occurred. 205// 206static bool is_statbuf_secure(struct stat *statp) { 207 if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) { 208 // The path represents a link or some non-directory file type, 209 // which is not what we expected. Declare it insecure. 210 // 211 return false; 212 } 213 // We have an existing directory, check if the permissions are safe. 214 // 215 if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) { 216 // The directory is open for writing and could be subjected 217 // to a symlink or a hard link attack. Declare it insecure. 218 // 219 return false; 220 } 221 // If user is not root then see if the uid of the directory matches the effective uid of the process. 222 uid_t euid = geteuid(); 223 if ((euid != 0) && (statp->st_uid != euid)) { 224 // The directory was not created by this user, declare it insecure. 225 // 226 return false; 227 } 228 return true; 229} 230 231 232// Check if the given path is considered a secure directory for 233// the backing store files. Returns true if the directory exists 234// and is considered a secure location. Returns false if the path 235// is a symbolic link or if an error occurred. 236// 237static bool is_directory_secure(const char* path) { 238 struct stat statbuf; 239 int result = 0; 240 241 RESTARTABLE(::lstat(path, &statbuf), result); 242 if (result == OS_ERR) { 243 return false; 244 } 245 246 // The path exists, see if it is secure. 247 return is_statbuf_secure(&statbuf); 248} 249 250 251// Check if the given directory file descriptor is considered a secure 252// directory for the backing store files. Returns true if the directory 253// exists and is considered a secure location. Returns false if the path 254// is a symbolic link or if an error occurred. 255// 256static bool is_dirfd_secure(int dir_fd) { 257 struct stat statbuf; 258 int result = 0; 259 260 RESTARTABLE(::fstat(dir_fd, &statbuf), result); 261 if (result == OS_ERR) { 262 return false; 263 } 264 265 // The path exists, now check its mode. 266 return is_statbuf_secure(&statbuf); 267} 268 269 270// Check to make sure fd1 and fd2 are referencing the same file system object. 271// 272static bool is_same_fsobject(int fd1, int fd2) { 273 struct stat statbuf1; 274 struct stat statbuf2; 275 int result = 0; 276 277 RESTARTABLE(::fstat(fd1, &statbuf1), result); 278 if (result == OS_ERR) { 279 return false; 280 } 281 RESTARTABLE(::fstat(fd2, &statbuf2), result); 282 if (result == OS_ERR) { 283 return false; 284 } 285 286 if ((statbuf1.st_ino == statbuf2.st_ino) && 287 (statbuf1.st_dev == statbuf2.st_dev)) { 288 return true; 289 } else { 290 return false; 291 } 292} 293 294 295// Open the directory of the given path and validate it. 296// Return a DIR * of the open directory. 297// 298static DIR *open_directory_secure(const char* dirname) { 299 // Open the directory using open() so that it can be verified 300 // to be secure by calling is_dirfd_secure(), opendir() and then check 301 // to see if they are the same file system object. This method does not 302 // introduce a window of opportunity for the directory to be attacked that 303 // calling opendir() and is_directory_secure() does. 304 int result; 305 DIR *dirp = NULL; 306 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result); 307 if (result == OS_ERR) { 308 // Directory doesn't exist or is a symlink, so there is nothing to cleanup. 309 if (PrintMiscellaneous && Verbose) { 310 if (errno == ELOOP) { 311 warning("directory %s is a symlink and is not secure\n", dirname); 312 } else { 313 warning("could not open directory %s: %s\n", dirname, os::strerror(errno)); 314 } 315 } 316 return dirp; 317 } 318 int fd = result; 319 320 // Determine if the open directory is secure. 321 if (!is_dirfd_secure(fd)) { 322 // The directory is not a secure directory. 323 os::close(fd); 324 return dirp; 325 } 326 327 // Open the directory. 328 dirp = ::opendir(dirname); 329 if (dirp == NULL) { 330 // The directory doesn't exist, close fd and return. 331 os::close(fd); 332 return dirp; 333 } 334 335 // Check to make sure fd and dirp are referencing the same file system object. 336 if (!is_same_fsobject(fd, dirfd(dirp))) { 337 // The directory is not secure. 338 os::close(fd); 339 os::closedir(dirp); 340 dirp = NULL; 341 return dirp; 342 } 343 344 // Close initial open now that we know directory is secure 345 os::close(fd); 346 347 return dirp; 348} 349 350// NOTE: The code below uses fchdir(), open() and unlink() because 351// fdopendir(), openat() and unlinkat() are not supported on all 352// versions. Once the support for fdopendir(), openat() and unlinkat() 353// is available on all supported versions the code can be changed 354// to use these functions. 355 356// Open the directory of the given path, validate it and set the 357// current working directory to it. 358// Return a DIR * of the open directory and the saved cwd fd. 359// 360static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) { 361 362 // Open the directory. 363 DIR* dirp = open_directory_secure(dirname); 364 if (dirp == NULL) { 365 // Directory doesn't exist or is insecure, so there is nothing to cleanup. 366 return dirp; 367 } 368 int fd = dirfd(dirp); 369 370 // Open a fd to the cwd and save it off. 371 int result; 372 RESTARTABLE(::open(".", O_RDONLY), result); 373 if (result == OS_ERR) { 374 *saved_cwd_fd = -1; 375 } else { 376 *saved_cwd_fd = result; 377 } 378 379 // Set the current directory to dirname by using the fd of the directory and 380 // handle errors, otherwise shared memory files will be created in cwd. 381 result = fchdir(fd); 382 if (result == OS_ERR) { 383 if (PrintMiscellaneous && Verbose) { 384 warning("could not change to directory %s", dirname); 385 } 386 if (*saved_cwd_fd != -1) { 387 ::close(*saved_cwd_fd); 388 *saved_cwd_fd = -1; 389 } 390 // Close the directory. 391 os::closedir(dirp); 392 return NULL; 393 } else { 394 return dirp; 395 } 396} 397 398// Close the directory and restore the current working directory. 399// 400static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) { 401 402 int result; 403 // If we have a saved cwd change back to it and close the fd. 404 if (saved_cwd_fd != -1) { 405 result = fchdir(saved_cwd_fd); 406 ::close(saved_cwd_fd); 407 } 408 409 // Close the directory. 410 os::closedir(dirp); 411} 412 413// Check if the given file descriptor is considered a secure. 414// 415static bool is_file_secure(int fd, const char *filename) { 416 417 int result; 418 struct stat statbuf; 419 420 // Determine if the file is secure. 421 RESTARTABLE(::fstat(fd, &statbuf), result); 422 if (result == OS_ERR) { 423 if (PrintMiscellaneous && Verbose) { 424 warning("fstat failed on %s: %s\n", filename, os::strerror(errno)); 425 } 426 return false; 427 } 428 if (statbuf.st_nlink > 1) { 429 // A file with multiple links is not expected. 430 if (PrintMiscellaneous && Verbose) { 431 warning("file %s has multiple links\n", filename); 432 } 433 return false; 434 } 435 return true; 436} 437 438// return the user name for the given user id 439// 440// the caller is expected to free the allocated memory. 441// 442static char* get_user_name(uid_t uid) { 443 444 struct passwd pwent; 445 446 // determine the max pwbuf size from sysconf, and hardcode 447 // a default if this not available through sysconf. 448 // 449 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); 450 if (bufsize == -1) 451 bufsize = 1024; 452 453 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 454 455 // POSIX interface to getpwuid_r is used on LINUX 456 struct passwd* p; 457 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 458 459 if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 460 if (PrintMiscellaneous && Verbose) { 461 if (result != 0) { 462 warning("Could not retrieve passwd entry: %s\n", 463 os::strerror(result)); 464 } 465 else if (p == NULL) { 466 // this check is added to protect against an observed problem 467 // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0, 468 // indicating success, but has p == NULL. This was observed when 469 // inserting a file descriptor exhaustion fault prior to the call 470 // getpwuid_r() call. In this case, error is set to the appropriate 471 // error condition, but this is undocumented behavior. This check 472 // is safe under any condition, but the use of errno in the output 473 // message may result in an erroneous message. 474 // Bug Id 89052 was opened with RedHat. 475 // 476 warning("Could not retrieve passwd entry: %s\n", 477 os::strerror(errno)); 478 } 479 else { 480 warning("Could not determine user name: %s\n", 481 p->pw_name == NULL ? "pw_name = NULL" : 482 "pw_name zero length"); 483 } 484 } 485 FREE_C_HEAP_ARRAY(char, pwbuf); 486 return NULL; 487 } 488 489 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal); 490 strcpy(user_name, p->pw_name); 491 492 FREE_C_HEAP_ARRAY(char, pwbuf); 493 return user_name; 494} 495 496// return the name of the user that owns the process identified by vmid. 497// 498// This method uses a slow directory search algorithm to find the backing 499// store file for the specified vmid and returns the user name, as determined 500// by the user name suffix of the hsperfdata_<username> directory name. 501// 502// the caller is expected to free the allocated memory. 503// 504static char* get_user_name_slow(int vmid, TRAPS) { 505 506 // short circuit the directory search if the process doesn't even exist. 507 if (kill(vmid, 0) == OS_ERR) { 508 if (errno == ESRCH) { 509 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 510 "Process not found"); 511 } 512 else /* EPERM */ { 513 THROW_MSG_0(vmSymbols::java_io_IOException(), os::strerror(errno)); 514 } 515 } 516 517 // directory search 518 char* oldest_user = NULL; 519 time_t oldest_ctime = 0; 520 521 const char* tmpdirname = os::get_temp_directory(); 522 523 // open the temp directory 524 DIR* tmpdirp = os::opendir(tmpdirname); 525 526 if (tmpdirp == NULL) { 527 // Cannot open the directory to get the user name, return. 528 return NULL; 529 } 530 531 // for each entry in the directory that matches the pattern hsperfdata_*, 532 // open the directory and check if the file for the given vmid exists. 533 // The file with the expected name and the latest creation date is used 534 // to determine the user name for the process id. 535 // 536 struct dirent* dentry; 537 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal); 538 errno = 0; 539 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) { 540 541 // check if the directory entry is a hsperfdata file 542 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { 543 continue; 544 } 545 546 char* usrdir_name = NEW_C_HEAP_ARRAY(char, 547 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal); 548 strcpy(usrdir_name, tmpdirname); 549 strcat(usrdir_name, "/"); 550 strcat(usrdir_name, dentry->d_name); 551 552 // open the user directory 553 DIR* subdirp = open_directory_secure(usrdir_name); 554 555 if (subdirp == NULL) { 556 FREE_C_HEAP_ARRAY(char, usrdir_name); 557 continue; 558 } 559 560 struct dirent* udentry; 561 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal); 562 errno = 0; 563 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) { 564 565 if (filename_to_pid(udentry->d_name) == vmid) { 566 struct stat statbuf; 567 int result; 568 569 char* filename = NEW_C_HEAP_ARRAY(char, 570 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal); 571 572 strcpy(filename, usrdir_name); 573 strcat(filename, "/"); 574 strcat(filename, udentry->d_name); 575 576 // don't follow symbolic links for the file 577 RESTARTABLE(::lstat(filename, &statbuf), result); 578 if (result == OS_ERR) { 579 FREE_C_HEAP_ARRAY(char, filename); 580 continue; 581 } 582 583 // skip over files that are not regular files. 584 if (!S_ISREG(statbuf.st_mode)) { 585 FREE_C_HEAP_ARRAY(char, filename); 586 continue; 587 } 588 589 // compare and save filename with latest creation time 590 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { 591 592 if (statbuf.st_ctime > oldest_ctime) { 593 char* user = strchr(dentry->d_name, '_') + 1; 594 595 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user); 596 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal); 597 598 strcpy(oldest_user, user); 599 oldest_ctime = statbuf.st_ctime; 600 } 601 } 602 603 FREE_C_HEAP_ARRAY(char, filename); 604 } 605 } 606 os::closedir(subdirp); 607 FREE_C_HEAP_ARRAY(char, udbuf); 608 FREE_C_HEAP_ARRAY(char, usrdir_name); 609 } 610 os::closedir(tmpdirp); 611 FREE_C_HEAP_ARRAY(char, tdbuf); 612 613 return(oldest_user); 614} 615 616// return the name of the user that owns the JVM indicated by the given vmid. 617// 618static char* get_user_name(int vmid, TRAPS) { 619 return get_user_name_slow(vmid, THREAD); 620} 621 622// return the file name of the backing store file for the named 623// shared memory region for the given user name and vmid. 624// 625// the caller is expected to free the allocated memory. 626// 627static char* get_sharedmem_filename(const char* dirname, int vmid) { 628 629 // add 2 for the file separator and a null terminator. 630 size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 631 632 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 633 snprintf(name, nbytes, "%s/%d", dirname, vmid); 634 635 return name; 636} 637 638 639// remove file 640// 641// this method removes the file specified by the given path 642// 643static void remove_file(const char* path) { 644 645 int result; 646 647 // if the file is a directory, the following unlink will fail. since 648 // we don't expect to find directories in the user temp directory, we 649 // won't try to handle this situation. even if accidentially or 650 // maliciously planted, the directory's presence won't hurt anything. 651 // 652 RESTARTABLE(::unlink(path), result); 653 if (PrintMiscellaneous && Verbose && result == OS_ERR) { 654 if (errno != ENOENT) { 655 warning("Could not unlink shared memory backing" 656 " store file %s : %s\n", path, os::strerror(errno)); 657 } 658 } 659} 660 661 662// cleanup stale shared memory resources 663// 664// This method attempts to remove all stale shared memory files in 665// the named user temporary directory. It scans the named directory 666// for files matching the pattern ^$[0-9]*$. For each file found, the 667// process id is extracted from the file name and a test is run to 668// determine if the process is alive. If the process is not alive, 669// any stale file resources are removed. 670// 671static void cleanup_sharedmem_resources(const char* dirname) { 672 673 int saved_cwd_fd; 674 // open the directory and set the current working directory to it 675 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 676 if (dirp == NULL) { 677 // directory doesn't exist or is insecure, so there is nothing to cleanup 678 return; 679 } 680 681 // for each entry in the directory that matches the expected file 682 // name pattern, determine if the file resources are stale and if 683 // so, remove the file resources. Note, instrumented HotSpot processes 684 // for this user may start and/or terminate during this search and 685 // remove or create new files in this directory. The behavior of this 686 // loop under these conditions is dependent upon the implementation of 687 // opendir/readdir. 688 // 689 struct dirent* entry; 690 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal); 691 692 errno = 0; 693 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) { 694 695 pid_t pid = filename_to_pid(entry->d_name); 696 697 if (pid == 0) { 698 699 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 700 701 // attempt to remove all unexpected files, except "." and ".." 702 unlink(entry->d_name); 703 } 704 705 errno = 0; 706 continue; 707 } 708 709 // we now have a file name that converts to a valid integer 710 // that could represent a process id . if this process id 711 // matches the current process id or the process is not running, 712 // then remove the stale file resources. 713 // 714 // process liveness is detected by sending signal number 0 to 715 // the process id (see kill(2)). if kill determines that the 716 // process does not exist, then the file resources are removed. 717 // if kill determines that that we don't have permission to 718 // signal the process, then the file resources are assumed to 719 // be stale and are removed because the resources for such a 720 // process should be in a different user specific directory. 721 // 722 if ((pid == os::current_process_id()) || 723 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 724 725 unlink(entry->d_name); 726 } 727 errno = 0; 728 } 729 730 // close the directory and reset the current working directory 731 close_directory_secure_cwd(dirp, saved_cwd_fd); 732 733 FREE_C_HEAP_ARRAY(char, dbuf); 734} 735 736// make the user specific temporary directory. Returns true if 737// the directory exists and is secure upon return. Returns false 738// if the directory exists but is either a symlink, is otherwise 739// insecure, or if an error occurred. 740// 741static bool make_user_tmp_dir(const char* dirname) { 742 743 // create the directory with 0755 permissions. note that the directory 744 // will be owned by euid::egid, which may not be the same as uid::gid. 745 // 746 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 747 if (errno == EEXIST) { 748 // The directory already exists and was probably created by another 749 // JVM instance. However, this could also be the result of a 750 // deliberate symlink. Verify that the existing directory is safe. 751 // 752 if (!is_directory_secure(dirname)) { 753 // directory is not secure 754 if (PrintMiscellaneous && Verbose) { 755 warning("%s directory is insecure\n", dirname); 756 } 757 return false; 758 } 759 } 760 else { 761 // we encountered some other failure while attempting 762 // to create the directory 763 // 764 if (PrintMiscellaneous && Verbose) { 765 warning("could not create directory %s: %s\n", 766 dirname, os::strerror(errno)); 767 } 768 return false; 769 } 770 } 771 return true; 772} 773 774// create the shared memory file resources 775// 776// This method creates the shared memory file with the given size 777// This method also creates the user specific temporary directory, if 778// it does not yet exist. 779// 780static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 781 782 // make the user temporary directory 783 if (!make_user_tmp_dir(dirname)) { 784 // could not make/find the directory or the found directory 785 // was not secure 786 return -1; 787 } 788 789 int saved_cwd_fd; 790 // open the directory and set the current working directory to it 791 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 792 if (dirp == NULL) { 793 // Directory doesn't exist or is insecure, so cannot create shared 794 // memory file. 795 return -1; 796 } 797 798 // Open the filename in the current directory. 799 // Cannot use O_TRUNC here; truncation of an existing file has to happen 800 // after the is_file_secure() check below. 801 int result; 802 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result); 803 if (result == OS_ERR) { 804 if (PrintMiscellaneous && Verbose) { 805 if (errno == ELOOP) { 806 warning("file %s is a symlink and is not secure\n", filename); 807 } else { 808 warning("could not create file %s: %s\n", filename, os::strerror(errno)); 809 } 810 } 811 // close the directory and reset the current working directory 812 close_directory_secure_cwd(dirp, saved_cwd_fd); 813 814 return -1; 815 } 816 // close the directory and reset the current working directory 817 close_directory_secure_cwd(dirp, saved_cwd_fd); 818 819 // save the file descriptor 820 int fd = result; 821 822 // check to see if the file is secure 823 if (!is_file_secure(fd, filename)) { 824 ::close(fd); 825 return -1; 826 } 827 828 // truncate the file to get rid of any existing data 829 RESTARTABLE(::ftruncate(fd, (off_t)0), result); 830 if (result == OS_ERR) { 831 if (PrintMiscellaneous && Verbose) { 832 warning("could not truncate shared memory file: %s\n", os::strerror(errno)); 833 } 834 ::close(fd); 835 return -1; 836 } 837 // set the file size 838 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 839 if (result == OS_ERR) { 840 if (PrintMiscellaneous && Verbose) { 841 warning("could not set shared memory file size: %s\n", os::strerror(errno)); 842 } 843 ::close(fd); 844 return -1; 845 } 846 847 // Verify that we have enough disk space for this file. 848 // We'll get random SIGBUS crashes on memory accesses if 849 // we don't. 850 851 for (size_t seekpos = 0; seekpos < size; seekpos += os::vm_page_size()) { 852 int zero_int = 0; 853 result = (int)os::seek_to_file_offset(fd, (jlong)(seekpos)); 854 if (result == -1 ) break; 855 RESTARTABLE(::write(fd, &zero_int, 1), result); 856 if (result != 1) { 857 if (errno == ENOSPC) { 858 warning("Insufficient space for shared memory file:\n %s\nTry using the -Djava.io.tmpdir= option to select an alternate temp location.\n", filename); 859 } 860 break; 861 } 862 } 863 864 if (result != -1) { 865 return fd; 866 } else { 867 ::close(fd); 868 return -1; 869 } 870} 871 872// open the shared memory file for the given user and vmid. returns 873// the file descriptor for the open file or -1 if the file could not 874// be opened. 875// 876static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 877 878 // open the file 879 int result; 880 RESTARTABLE(::open(filename, oflags), result); 881 if (result == OS_ERR) { 882 if (errno == ENOENT) { 883 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 884 "Process not found", OS_ERR); 885 } 886 else if (errno == EACCES) { 887 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 888 "Permission denied", OS_ERR); 889 } 890 else { 891 THROW_MSG_(vmSymbols::java_io_IOException(), os::strerror(errno), OS_ERR); 892 } 893 } 894 int fd = result; 895 896 // check to see if the file is secure 897 if (!is_file_secure(fd, filename)) { 898 ::close(fd); 899 return -1; 900 } 901 902 return fd; 903} 904 905// create a named shared memory region. returns the address of the 906// memory region on success or NULL on failure. A return value of 907// NULL will ultimately disable the shared memory feature. 908// 909// On Solaris and Bsd, the name space for shared memory objects 910// is the file system name space. 911// 912// A monitoring application attaching to a JVM does not need to know 913// the file system name of the shared memory object. However, it may 914// be convenient for applications to discover the existence of newly 915// created and terminating JVMs by watching the file system name space 916// for files being created or removed. 917// 918static char* mmap_create_shared(size_t size) { 919 920 int result; 921 int fd; 922 char* mapAddress; 923 924 int vmid = os::current_process_id(); 925 926 char* user_name = get_user_name(geteuid()); 927 928 if (user_name == NULL) 929 return NULL; 930 931 char* dirname = get_user_tmp_dir(user_name); 932 char* filename = get_sharedmem_filename(dirname, vmid); 933 934 // get the short filename 935 char* short_filename = strrchr(filename, '/'); 936 if (short_filename == NULL) { 937 short_filename = filename; 938 } else { 939 short_filename++; 940 } 941 942 // cleanup any stale shared memory files 943 cleanup_sharedmem_resources(dirname); 944 945 assert(((size > 0) && (size % os::vm_page_size() == 0)), 946 "unexpected PerfMemory region size"); 947 948 fd = create_sharedmem_resources(dirname, short_filename, size); 949 950 FREE_C_HEAP_ARRAY(char, user_name); 951 FREE_C_HEAP_ARRAY(char, dirname); 952 953 if (fd == -1) { 954 FREE_C_HEAP_ARRAY(char, filename); 955 return NULL; 956 } 957 958 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 959 960 result = ::close(fd); 961 assert(result != OS_ERR, "could not close file"); 962 963 if (mapAddress == MAP_FAILED) { 964 if (PrintMiscellaneous && Verbose) { 965 warning("mmap failed - %s\n", os::strerror(errno)); 966 } 967 remove_file(filename); 968 FREE_C_HEAP_ARRAY(char, filename); 969 return NULL; 970 } 971 972 // save the file name for use in delete_shared_memory() 973 backing_store_file_name = filename; 974 975 // clear the shared memory region 976 (void)::memset((void*) mapAddress, 0, size); 977 978 // it does not go through os api, the operation has to record from here 979 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal); 980 981 return mapAddress; 982} 983 984// release a named shared memory region 985// 986static void unmap_shared(char* addr, size_t bytes) { 987 os::release_memory(addr, bytes); 988} 989 990// create the PerfData memory region in shared memory. 991// 992static char* create_shared_memory(size_t size) { 993 994 // create the shared memory region. 995 return mmap_create_shared(size); 996} 997 998// delete the shared PerfData memory region 999// 1000static void delete_shared_memory(char* addr, size_t size) { 1001 1002 // cleanup the persistent shared memory resources. since DestroyJavaVM does 1003 // not support unloading of the JVM, unmapping of the memory resource is 1004 // not performed. The memory will be reclaimed by the OS upon termination of 1005 // the process. The backing store file is deleted from the file system. 1006 1007 assert(!PerfDisableSharedMem, "shouldn't be here"); 1008 1009 if (backing_store_file_name != NULL) { 1010 remove_file(backing_store_file_name); 1011 // Don't.. Free heap memory could deadlock os::abort() if it is called 1012 // from signal handler. OS will reclaim the heap memory. 1013 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 1014 backing_store_file_name = NULL; 1015 } 1016} 1017 1018// return the size of the file for the given file descriptor 1019// or 0 if it is not a valid size for a shared memory file 1020// 1021static size_t sharedmem_filesize(int fd, TRAPS) { 1022 1023 struct stat statbuf; 1024 int result; 1025 1026 RESTARTABLE(::fstat(fd, &statbuf), result); 1027 if (result == OS_ERR) { 1028 if (PrintMiscellaneous && Verbose) { 1029 warning("fstat failed: %s\n", os::strerror(errno)); 1030 } 1031 THROW_MSG_0(vmSymbols::java_io_IOException(), 1032 "Could not determine PerfMemory size"); 1033 } 1034 1035 if ((statbuf.st_size == 0) || 1036 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 1037 THROW_MSG_0(vmSymbols::java_lang_Exception(), 1038 "Invalid PerfMemory size"); 1039 } 1040 1041 return (size_t)statbuf.st_size; 1042} 1043 1044// attach to a named shared memory region. 1045// 1046static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 1047 1048 char* mapAddress; 1049 int result; 1050 int fd; 1051 size_t size = 0; 1052 const char* luser = NULL; 1053 1054 int mmap_prot; 1055 int file_flags; 1056 1057 ResourceMark rm; 1058 1059 // map the high level access mode to the appropriate permission 1060 // constructs for the file and the shared memory mapping. 1061 if (mode == PerfMemory::PERF_MODE_RO) { 1062 mmap_prot = PROT_READ; 1063 file_flags = O_RDONLY | O_NOFOLLOW; 1064 } 1065 else if (mode == PerfMemory::PERF_MODE_RW) { 1066#ifdef LATER 1067 mmap_prot = PROT_READ | PROT_WRITE; 1068 file_flags = O_RDWR | O_NOFOLLOW; 1069#else 1070 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1071 "Unsupported access mode"); 1072#endif 1073 } 1074 else { 1075 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1076 "Illegal access mode"); 1077 } 1078 1079 if (user == NULL || strlen(user) == 0) { 1080 luser = get_user_name(vmid, CHECK); 1081 } 1082 else { 1083 luser = user; 1084 } 1085 1086 if (luser == NULL) { 1087 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1088 "Could not map vmid to user Name"); 1089 } 1090 1091 char* dirname = get_user_tmp_dir(luser); 1092 1093 // since we don't follow symbolic links when creating the backing 1094 // store file, we don't follow them when attaching either. 1095 // 1096 if (!is_directory_secure(dirname)) { 1097 FREE_C_HEAP_ARRAY(char, dirname); 1098 if (luser != user) { 1099 FREE_C_HEAP_ARRAY(char, luser); 1100 } 1101 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1102 "Process not found"); 1103 } 1104 1105 char* filename = get_sharedmem_filename(dirname, vmid); 1106 1107 // copy heap memory to resource memory. the open_sharedmem_file 1108 // method below need to use the filename, but could throw an 1109 // exception. using a resource array prevents the leak that 1110 // would otherwise occur. 1111 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); 1112 strcpy(rfilename, filename); 1113 1114 // free the c heap resources that are no longer needed 1115 if (luser != user) FREE_C_HEAP_ARRAY(char, luser); 1116 FREE_C_HEAP_ARRAY(char, dirname); 1117 FREE_C_HEAP_ARRAY(char, filename); 1118 1119 // open the shared memory file for the give vmid 1120 fd = open_sharedmem_file(rfilename, file_flags, CHECK); 1121 assert(fd != OS_ERR, "unexpected value"); 1122 1123 if (*sizep == 0) { 1124 size = sharedmem_filesize(fd, CHECK); 1125 } else { 1126 size = *sizep; 1127 } 1128 1129 assert(size > 0, "unexpected size <= 0"); 1130 1131 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 1132 1133 // attempt to close the file - restart if it gets interrupted, 1134 // but ignore other failures 1135 result = ::close(fd); 1136 assert(result != OS_ERR, "could not close file"); 1137 1138 if (mapAddress == MAP_FAILED) { 1139 if (PrintMiscellaneous && Verbose) { 1140 warning("mmap failed: %s\n", os::strerror(errno)); 1141 } 1142 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 1143 "Could not map PerfMemory"); 1144 } 1145 1146 // it does not go through os api, the operation has to record from here 1147 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal); 1148 1149 *addr = mapAddress; 1150 *sizep = size; 1151 1152 if (PerfTraceMemOps) { 1153 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at " 1154 INTPTR_FORMAT "\n", size, vmid, p2i((void*)mapAddress)); 1155 } 1156} 1157 1158 1159 1160 1161// create the PerfData memory region 1162// 1163// This method creates the memory region used to store performance 1164// data for the JVM. The memory may be created in standard or 1165// shared memory. 1166// 1167void PerfMemory::create_memory_region(size_t size) { 1168 1169 if (PerfDisableSharedMem) { 1170 // do not share the memory for the performance data. 1171 _start = create_standard_memory(size); 1172 } 1173 else { 1174 _start = create_shared_memory(size); 1175 if (_start == NULL) { 1176 1177 // creation of the shared memory region failed, attempt 1178 // to create a contiguous, non-shared memory region instead. 1179 // 1180 if (PrintMiscellaneous && Verbose) { 1181 warning("Reverting to non-shared PerfMemory region.\n"); 1182 } 1183 PerfDisableSharedMem = true; 1184 _start = create_standard_memory(size); 1185 } 1186 } 1187 1188 if (_start != NULL) _capacity = size; 1189 1190} 1191 1192// delete the PerfData memory region 1193// 1194// This method deletes the memory region used to store performance 1195// data for the JVM. The memory region indicated by the <address, size> 1196// tuple will be inaccessible after a call to this method. 1197// 1198void PerfMemory::delete_memory_region() { 1199 1200 assert((start() != NULL && capacity() > 0), "verify proper state"); 1201 1202 // If user specifies PerfDataSaveFile, it will save the performance data 1203 // to the specified file name no matter whether PerfDataSaveToFile is specified 1204 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 1205 // -XX:+PerfDataSaveToFile. 1206 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 1207 save_memory_to_file(start(), capacity()); 1208 } 1209 1210 if (PerfDisableSharedMem) { 1211 delete_standard_memory(start(), capacity()); 1212 } 1213 else { 1214 delete_shared_memory(start(), capacity()); 1215 } 1216} 1217 1218// attach to the PerfData memory region for another JVM 1219// 1220// This method returns an <address, size> tuple that points to 1221// a memory buffer that is kept reasonably synchronized with 1222// the PerfData memory region for the indicated JVM. This 1223// buffer may be kept in synchronization via shared memory 1224// or some other mechanism that keeps the buffer updated. 1225// 1226// If the JVM chooses not to support the attachability feature, 1227// this method should throw an UnsupportedOperation exception. 1228// 1229// This implementation utilizes named shared memory to map 1230// the indicated process's PerfData memory region into this JVMs 1231// address space. 1232// 1233void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1234 1235 if (vmid == 0 || vmid == os::current_process_id()) { 1236 *addrp = start(); 1237 *sizep = capacity(); 1238 return; 1239 } 1240 1241 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1242} 1243 1244// detach from the PerfData memory region of another JVM 1245// 1246// This method detaches the PerfData memory region of another 1247// JVM, specified as an <address, size> tuple of a buffer 1248// in this process's address space. This method may perform 1249// arbitrary actions to accomplish the detachment. The memory 1250// region specified by <address, size> will be inaccessible after 1251// a call to this method. 1252// 1253// If the JVM chooses not to support the attachability feature, 1254// this method should throw an UnsupportedOperation exception. 1255// 1256// This implementation utilizes named shared memory to detach 1257// the indicated process's PerfData memory region from this 1258// process's address space. 1259// 1260void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1261 1262 assert(addr != 0, "address sanity check"); 1263 assert(bytes > 0, "capacity sanity check"); 1264 1265 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1266 // prevent accidental detachment of this process's PerfMemory region 1267 return; 1268 } 1269 1270 unmap_shared(addr, bytes); 1271} 1272