perfMemory_aix.cpp revision 9339:9ff773cd4ba2
1/* 2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. 3 * Copyright 2012, 2013 SAP AG. All rights reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 * 24 */ 25 26#include "precompiled.hpp" 27#include "classfile/vmSymbols.hpp" 28#include "memory/allocation.inline.hpp" 29#include "memory/resourceArea.hpp" 30#include "oops/oop.inline.hpp" 31#include "os_aix.inline.hpp" 32#include "runtime/handles.inline.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, 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, strerror(errno)); 116 } 117 break; 118 } 119 120 remaining -= (size_t)result; 121 addr += result; 122 } 123 124 RESTARTABLE(::close(fd), result); 125 if (PrintMiscellaneous && Verbose) { 126 if (result == OS_ERR) { 127 warning("Could not close %s: %s\n", destfile, 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 linux 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 linux 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// Check if the given statbuf is considered a secure directory for 201// the backing store files. Returns true if the directory is considered 202// a secure location. Returns false if the statbuf is a symbolic link or 203// if an error occurred. 204// 205static bool is_statbuf_secure(struct stat *statp) { 206 if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) { 207 // The path represents a link or some non-directory file type, 208 // which is not what we expected. Declare it insecure. 209 // 210 return false; 211 } 212 // We have an existing directory, check if the permissions are safe. 213 // 214 if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) { 215 // The directory is open for writing and could be subjected 216 // to a symlink or a hard link attack. Declare it insecure. 217 // 218 return false; 219 } 220 // If user is not root then see if the uid of the directory matches the effective uid of the process. 221 uid_t euid = geteuid(); 222 if ((euid != 0) && (statp->st_uid != euid)) { 223 // The directory was not created by this user, declare it insecure. 224 // 225 return false; 226 } 227 return true; 228} 229 230 231// Check if the given path is considered a secure directory for 232// the backing store files. Returns true if the directory exists 233// and is considered a secure location. Returns false if the path 234// is a symbolic link or if an error occurred. 235// 236static bool is_directory_secure(const char* path) { 237 struct stat statbuf; 238 int result = 0; 239 240 RESTARTABLE(::lstat(path, &statbuf), result); 241 if (result == OS_ERR) { 242 return false; 243 } 244 245 // The path exists, see if it is secure. 246 return is_statbuf_secure(&statbuf); 247} 248 249// (Taken over from Solaris to support the O_NOFOLLOW case on AIX.) 250// Check if the given directory file descriptor is considered a secure 251// directory for the backing store files. Returns true if the directory 252// exists and is considered a secure location. Returns false if the path 253// is a symbolic link or if an error occurred. 254static bool is_dirfd_secure(int dir_fd) { 255 struct stat statbuf; 256 int result = 0; 257 258 RESTARTABLE(::fstat(dir_fd, &statbuf), result); 259 if (result == OS_ERR) { 260 return false; 261 } 262 263 // The path exists, now check its mode. 264 return is_statbuf_secure(&statbuf); 265} 266 267 268// Check to make sure fd1 and fd2 are referencing the same file system object. 269static bool is_same_fsobject(int fd1, int fd2) { 270 struct stat statbuf1; 271 struct stat statbuf2; 272 int result = 0; 273 274 RESTARTABLE(::fstat(fd1, &statbuf1), result); 275 if (result == OS_ERR) { 276 return false; 277 } 278 RESTARTABLE(::fstat(fd2, &statbuf2), result); 279 if (result == OS_ERR) { 280 return false; 281 } 282 283 if ((statbuf1.st_ino == statbuf2.st_ino) && 284 (statbuf1.st_dev == statbuf2.st_dev)) { 285 return true; 286 } else { 287 return false; 288 } 289} 290 291// Helper functions for open without O_NOFOLLOW which is not present on AIX 5.3/6.1. 292// We use the jdk6 implementation here. 293#ifndef O_NOFOLLOW 294// The O_NOFOLLOW oflag doesn't exist before solaris 5.10, this is to simulate that behaviour 295// was done in jdk 5/6 hotspot by Oracle this way 296static int open_o_nofollow_impl(const char* path, int oflag, mode_t mode, bool use_mode) { 297 struct stat orig_st; 298 struct stat new_st; 299 bool create; 300 int error; 301 int fd; 302 303 create = false; 304 305 if (lstat(path, &orig_st) != 0) { 306 if (errno == ENOENT && (oflag & O_CREAT) != 0) { 307 // File doesn't exist, but_we want to create it, add O_EXCL flag 308 // to make sure no-one creates it (or a symlink) before us 309 // This works as we expect with symlinks, from posix man page: 310 // 'If O_EXCL and O_CREAT are set, and path names a symbolic 311 // link, open() shall fail and set errno to [EEXIST]'. 312 oflag |= O_EXCL; 313 create = true; 314 } else { 315 // File doesn't exist, and we are not creating it. 316 return OS_ERR; 317 } 318 } else { 319 // Lstat success, check if existing file is a link. 320 if ((orig_st.st_mode & S_IFMT) == S_IFLNK) { 321 // File is a symlink. 322 errno = ELOOP; 323 return OS_ERR; 324 } 325 } 326 327 if (use_mode == true) { 328 fd = open(path, oflag, mode); 329 } else { 330 fd = open(path, oflag); 331 } 332 333 if (fd == OS_ERR) { 334 return fd; 335 } 336 337 // Can't do inode checks on before/after if we created the file. 338 if (create == false) { 339 if (fstat(fd, &new_st) != 0) { 340 // Keep errno from fstat, in case close also fails. 341 error = errno; 342 ::close(fd); 343 errno = error; 344 return OS_ERR; 345 } 346 347 if (orig_st.st_dev != new_st.st_dev || orig_st.st_ino != new_st.st_ino) { 348 // File was tampered with during race window. 349 ::close(fd); 350 errno = EEXIST; 351 if (PrintMiscellaneous && Verbose) { 352 warning("possible file tampering attempt detected when opening %s", path); 353 } 354 return OS_ERR; 355 } 356 } 357 358 return fd; 359} 360 361static int open_o_nofollow(const char* path, int oflag, mode_t mode) { 362 return open_o_nofollow_impl(path, oflag, mode, true); 363} 364 365static int open_o_nofollow(const char* path, int oflag) { 366 return open_o_nofollow_impl(path, oflag, 0, false); 367} 368#endif 369 370// Open the directory of the given path and validate it. 371// Return a DIR * of the open directory. 372static DIR *open_directory_secure(const char* dirname) { 373 // Open the directory using open() so that it can be verified 374 // to be secure by calling is_dirfd_secure(), opendir() and then check 375 // to see if they are the same file system object. This method does not 376 // introduce a window of opportunity for the directory to be attacked that 377 // calling opendir() and is_directory_secure() does. 378 int result; 379 DIR *dirp = NULL; 380 381 // No O_NOFOLLOW defined at buildtime, and it is not documented for open; 382 // so provide a workaround in this case. 383#ifdef O_NOFOLLOW 384 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result); 385#else 386 // workaround (jdk6 coding) 387 RESTARTABLE(::open_o_nofollow(dirname, O_RDONLY), result); 388#endif 389 390 if (result == OS_ERR) { 391 // Directory doesn't exist or is a symlink, so there is nothing to cleanup. 392 if (PrintMiscellaneous && Verbose) { 393 if (errno == ELOOP) { 394 warning("directory %s is a symlink and is not secure\n", dirname); 395 } else { 396 warning("could not open directory %s: %s\n", dirname, strerror(errno)); 397 } 398 } 399 return dirp; 400 } 401 int fd = result; 402 403 // Determine if the open directory is secure. 404 if (!is_dirfd_secure(fd)) { 405 // The directory is not a secure directory. 406 os::close(fd); 407 return dirp; 408 } 409 410 // Open the directory. 411 dirp = ::opendir(dirname); 412 if (dirp == NULL) { 413 // The directory doesn't exist, close fd and return. 414 os::close(fd); 415 return dirp; 416 } 417 418 // Check to make sure fd and dirp are referencing the same file system object. 419 if (!is_same_fsobject(fd, dirp->dd_fd)) { 420 // The directory is not secure. 421 os::close(fd); 422 os::closedir(dirp); 423 dirp = NULL; 424 return dirp; 425 } 426 427 // Close initial open now that we know directory is secure 428 os::close(fd); 429 430 return dirp; 431} 432 433// NOTE: The code below uses fchdir(), open() and unlink() because 434// fdopendir(), openat() and unlinkat() are not supported on all 435// versions. Once the support for fdopendir(), openat() and unlinkat() 436// is available on all supported versions the code can be changed 437// to use these functions. 438 439// Open the directory of the given path, validate it and set the 440// current working directory to it. 441// Return a DIR * of the open directory and the saved cwd fd. 442// 443static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) { 444 445 // Open the directory. 446 DIR* dirp = open_directory_secure(dirname); 447 if (dirp == NULL) { 448 // Directory doesn't exist or is insecure, so there is nothing to cleanup. 449 return dirp; 450 } 451 int fd = dirp->dd_fd; 452 453 // Open a fd to the cwd and save it off. 454 int result; 455 RESTARTABLE(::open(".", O_RDONLY), result); 456 if (result == OS_ERR) { 457 *saved_cwd_fd = -1; 458 } else { 459 *saved_cwd_fd = result; 460 } 461 462 // Set the current directory to dirname by using the fd of the directory and 463 // handle errors, otherwise shared memory files will be created in cwd. 464 result = fchdir(fd); 465 if (result == OS_ERR) { 466 if (PrintMiscellaneous && Verbose) { 467 warning("could not change to directory %s", dirname); 468 } 469 if (*saved_cwd_fd != -1) { 470 ::close(*saved_cwd_fd); 471 *saved_cwd_fd = -1; 472 } 473 // Close the directory. 474 os::closedir(dirp); 475 return NULL; 476 } else { 477 return dirp; 478 } 479} 480 481// Close the directory and restore the current working directory. 482// 483static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) { 484 485 int result; 486 // If we have a saved cwd change back to it and close the fd. 487 if (saved_cwd_fd != -1) { 488 result = fchdir(saved_cwd_fd); 489 ::close(saved_cwd_fd); 490 } 491 492 // Close the directory. 493 os::closedir(dirp); 494} 495 496// Check if the given file descriptor is considered a secure. 497static bool is_file_secure(int fd, const char *filename) { 498 499 int result; 500 struct stat statbuf; 501 502 // Determine if the file is secure. 503 RESTARTABLE(::fstat(fd, &statbuf), result); 504 if (result == OS_ERR) { 505 if (PrintMiscellaneous && Verbose) { 506 warning("fstat failed on %s: %s\n", filename, strerror(errno)); 507 } 508 return false; 509 } 510 if (statbuf.st_nlink > 1) { 511 // A file with multiple links is not expected. 512 if (PrintMiscellaneous && Verbose) { 513 warning("file %s has multiple links\n", filename); 514 } 515 return false; 516 } 517 return true; 518} 519 520// Return the user name for the given user id. 521// 522// The caller is expected to free the allocated memory. 523static char* get_user_name(uid_t uid) { 524 525 struct passwd pwent; 526 527 // Determine the max pwbuf size from sysconf, and hardcode 528 // a default if this not available through sysconf. 529 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); 530 if (bufsize == -1) 531 bufsize = 1024; 532 533 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 534 535 // POSIX interface to getpwuid_r is used on LINUX 536 struct passwd* p; 537 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 538 539 if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 540 if (PrintMiscellaneous && Verbose) { 541 if (result != 0) { 542 warning("Could not retrieve passwd entry: %s\n", 543 strerror(result)); 544 } 545 else if (p == NULL) { 546 // this check is added to protect against an observed problem 547 // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0, 548 // indicating success, but has p == NULL. This was observed when 549 // inserting a file descriptor exhaustion fault prior to the call 550 // getpwuid_r() call. In this case, error is set to the appropriate 551 // error condition, but this is undocumented behavior. This check 552 // is safe under any condition, but the use of errno in the output 553 // message may result in an erroneous message. 554 // Bug Id 89052 was opened with RedHat. 555 // 556 warning("Could not retrieve passwd entry: %s\n", 557 strerror(errno)); 558 } 559 else { 560 warning("Could not determine user name: %s\n", 561 p->pw_name == NULL ? "pw_name = NULL" : 562 "pw_name zero length"); 563 } 564 } 565 FREE_C_HEAP_ARRAY(char, pwbuf); 566 return NULL; 567 } 568 569 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal); 570 strcpy(user_name, p->pw_name); 571 572 FREE_C_HEAP_ARRAY(char, pwbuf); 573 return user_name; 574} 575 576// return the name of the user that owns the process identified by vmid. 577// 578// This method uses a slow directory search algorithm to find the backing 579// store file for the specified vmid and returns the user name, as determined 580// by the user name suffix of the hsperfdata_<username> directory name. 581// 582// the caller is expected to free the allocated memory. 583// 584static char* get_user_name_slow(int vmid, TRAPS) { 585 586 // short circuit the directory search if the process doesn't even exist. 587 if (kill(vmid, 0) == OS_ERR) { 588 if (errno == ESRCH) { 589 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 590 "Process not found"); 591 } 592 else /* EPERM */ { 593 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno)); 594 } 595 } 596 597 // directory search 598 char* oldest_user = NULL; 599 time_t oldest_ctime = 0; 600 601 const char* tmpdirname = os::get_temp_directory(); 602 603 DIR* tmpdirp = os::opendir(tmpdirname); 604 605 if (tmpdirp == NULL) { 606 return NULL; 607 } 608 609 // for each entry in the directory that matches the pattern hsperfdata_*, 610 // open the directory and check if the file for the given vmid exists. 611 // The file with the expected name and the latest creation date is used 612 // to determine the user name for the process id. 613 // 614 struct dirent* dentry; 615 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal); 616 errno = 0; 617 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) { 618 619 // check if the directory entry is a hsperfdata file 620 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { 621 continue; 622 } 623 624 char* usrdir_name = NEW_C_HEAP_ARRAY(char, 625 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal); 626 strcpy(usrdir_name, tmpdirname); 627 strcat(usrdir_name, "/"); 628 strcat(usrdir_name, dentry->d_name); 629 630 // Open the user directory. 631 DIR* subdirp = open_directory_secure(usrdir_name); 632 633 if (subdirp == NULL) { 634 FREE_C_HEAP_ARRAY(char, usrdir_name); 635 continue; 636 } 637 638 // Since we don't create the backing store files in directories 639 // pointed to by symbolic links, we also don't follow them when 640 // looking for the files. We check for a symbolic link after the 641 // call to opendir in order to eliminate a small window where the 642 // symlink can be exploited. 643 // 644 if (!is_directory_secure(usrdir_name)) { 645 FREE_C_HEAP_ARRAY(char, usrdir_name); 646 os::closedir(subdirp); 647 continue; 648 } 649 650 struct dirent* udentry; 651 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal); 652 errno = 0; 653 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) { 654 655 if (filename_to_pid(udentry->d_name) == vmid) { 656 struct stat statbuf; 657 int result; 658 659 char* filename = NEW_C_HEAP_ARRAY(char, 660 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal); 661 662 strcpy(filename, usrdir_name); 663 strcat(filename, "/"); 664 strcat(filename, udentry->d_name); 665 666 // don't follow symbolic links for the file 667 RESTARTABLE(::lstat(filename, &statbuf), result); 668 if (result == OS_ERR) { 669 FREE_C_HEAP_ARRAY(char, filename); 670 continue; 671 } 672 673 // skip over files that are not regular files. 674 if (!S_ISREG(statbuf.st_mode)) { 675 FREE_C_HEAP_ARRAY(char, filename); 676 continue; 677 } 678 679 // compare and save filename with latest creation time 680 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { 681 682 if (statbuf.st_ctime > oldest_ctime) { 683 char* user = strchr(dentry->d_name, '_') + 1; 684 685 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user); 686 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal); 687 688 strcpy(oldest_user, user); 689 oldest_ctime = statbuf.st_ctime; 690 } 691 } 692 693 FREE_C_HEAP_ARRAY(char, filename); 694 } 695 } 696 os::closedir(subdirp); 697 FREE_C_HEAP_ARRAY(char, udbuf); 698 FREE_C_HEAP_ARRAY(char, usrdir_name); 699 } 700 os::closedir(tmpdirp); 701 FREE_C_HEAP_ARRAY(char, tdbuf); 702 703 return(oldest_user); 704} 705 706// return the name of the user that owns the JVM indicated by the given vmid. 707// 708static char* get_user_name(int vmid, TRAPS) { 709 return get_user_name_slow(vmid, THREAD); 710} 711 712// return the file name of the backing store file for the named 713// shared memory region for the given user name and vmid. 714// 715// the caller is expected to free the allocated memory. 716// 717static char* get_sharedmem_filename(const char* dirname, int vmid) { 718 719 // add 2 for the file separator and a null terminator. 720 size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 721 722 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 723 snprintf(name, nbytes, "%s/%d", dirname, vmid); 724 725 return name; 726} 727 728 729// remove file 730// 731// this method removes the file specified by the given path 732// 733static void remove_file(const char* path) { 734 735 int result; 736 737 // if the file is a directory, the following unlink will fail. since 738 // we don't expect to find directories in the user temp directory, we 739 // won't try to handle this situation. even if accidentially or 740 // maliciously planted, the directory's presence won't hurt anything. 741 // 742 RESTARTABLE(::unlink(path), result); 743 if (PrintMiscellaneous && Verbose && result == OS_ERR) { 744 if (errno != ENOENT) { 745 warning("Could not unlink shared memory backing" 746 " store file %s : %s\n", path, strerror(errno)); 747 } 748 } 749} 750 751// Cleanup stale shared memory resources 752// 753// This method attempts to remove all stale shared memory files in 754// the named user temporary directory. It scans the named directory 755// for files matching the pattern ^$[0-9]*$. For each file found, the 756// process id is extracted from the file name and a test is run to 757// determine if the process is alive. If the process is not alive, 758// any stale file resources are removed. 759static void cleanup_sharedmem_resources(const char* dirname) { 760 761 int saved_cwd_fd; 762 // Open the directory. 763 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 764 if (dirp == NULL) { 765 // Directory doesn't exist or is insecure, so there is nothing to cleanup. 766 return; 767 } 768 769 // For each entry in the directory that matches the expected file 770 // name pattern, determine if the file resources are stale and if 771 // so, remove the file resources. Note, instrumented HotSpot processes 772 // for this user may start and/or terminate during this search and 773 // remove or create new files in this directory. The behavior of this 774 // loop under these conditions is dependent upon the implementation of 775 // opendir/readdir. 776 struct dirent* entry; 777 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal); 778 779 errno = 0; 780 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) { 781 782 pid_t pid = filename_to_pid(entry->d_name); 783 784 if (pid == 0) { 785 786 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 787 788 // Attempt to remove all unexpected files, except "." and "..". 789 unlink(entry->d_name); 790 } 791 792 errno = 0; 793 continue; 794 } 795 796 // We now have a file name that converts to a valid integer 797 // that could represent a process id . if this process id 798 // matches the current process id or the process is not running, 799 // then remove the stale file resources. 800 // 801 // Process liveness is detected by sending signal number 0 to 802 // the process id (see kill(2)). if kill determines that the 803 // process does not exist, then the file resources are removed. 804 // if kill determines that that we don't have permission to 805 // signal the process, then the file resources are assumed to 806 // be stale and are removed because the resources for such a 807 // process should be in a different user specific directory. 808 if ((pid == os::current_process_id()) || 809 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 810 811 unlink(entry->d_name); 812 } 813 errno = 0; 814 } 815 816 // Close the directory and reset the current working directory. 817 close_directory_secure_cwd(dirp, saved_cwd_fd); 818 819 FREE_C_HEAP_ARRAY(char, dbuf); 820} 821 822// Make the user specific temporary directory. Returns true if 823// the directory exists and is secure upon return. Returns false 824// if the directory exists but is either a symlink, is otherwise 825// insecure, or if an error occurred. 826static bool make_user_tmp_dir(const char* dirname) { 827 828 // Create the directory with 0755 permissions. note that the directory 829 // will be owned by euid::egid, which may not be the same as uid::gid. 830 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 831 if (errno == EEXIST) { 832 // The directory already exists and was probably created by another 833 // JVM instance. However, this could also be the result of a 834 // deliberate symlink. Verify that the existing directory is safe. 835 if (!is_directory_secure(dirname)) { 836 // Directory is not secure. 837 if (PrintMiscellaneous && Verbose) { 838 warning("%s directory is insecure\n", dirname); 839 } 840 return false; 841 } 842 } 843 else { 844 // we encountered some other failure while attempting 845 // to create the directory 846 // 847 if (PrintMiscellaneous && Verbose) { 848 warning("could not create directory %s: %s\n", 849 dirname, strerror(errno)); 850 } 851 return false; 852 } 853 } 854 return true; 855} 856 857// create the shared memory file resources 858// 859// This method creates the shared memory file with the given size 860// This method also creates the user specific temporary directory, if 861// it does not yet exist. 862// 863static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 864 865 // make the user temporary directory 866 if (!make_user_tmp_dir(dirname)) { 867 // could not make/find the directory or the found directory 868 // was not secure 869 return -1; 870 } 871 872 int saved_cwd_fd; 873 // Open the directory and set the current working directory to it. 874 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 875 if (dirp == NULL) { 876 // Directory doesn't exist or is insecure, so cannot create shared 877 // memory file. 878 return -1; 879 } 880 881 // Open the filename in the current directory. 882 // Cannot use O_TRUNC here; truncation of an existing file has to happen 883 // after the is_file_secure() check below. 884 int result; 885 886 // No O_NOFOLLOW defined at buildtime, and it is not documented for open; 887 // so provide a workaround in this case. 888#ifdef O_NOFOLLOW 889 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result); 890#else 891 // workaround function (jdk6 code) 892 RESTARTABLE(::open_o_nofollow(filename, O_RDWR|O_CREAT, S_IREAD|S_IWRITE), result); 893#endif 894 895 if (result == OS_ERR) { 896 if (PrintMiscellaneous && Verbose) { 897 if (errno == ELOOP) { 898 warning("file %s is a symlink and is not secure\n", filename); 899 } else { 900 warning("could not create file %s: %s\n", filename, strerror(errno)); 901 } 902 } 903 // Close the directory and reset the current working directory. 904 close_directory_secure_cwd(dirp, saved_cwd_fd); 905 906 return -1; 907 } 908 // Close the directory and reset the current working directory. 909 close_directory_secure_cwd(dirp, saved_cwd_fd); 910 911 // save the file descriptor 912 int fd = result; 913 914 // Check to see if the file is secure. 915 if (!is_file_secure(fd, filename)) { 916 ::close(fd); 917 return -1; 918 } 919 920 // Truncate the file to get rid of any existing data. 921 RESTARTABLE(::ftruncate(fd, (off_t)0), result); 922 if (result == OS_ERR) { 923 if (PrintMiscellaneous && Verbose) { 924 warning("could not truncate shared memory file: %s\n", strerror(errno)); 925 } 926 ::close(fd); 927 return -1; 928 } 929 // set the file size 930 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 931 if (result == OS_ERR) { 932 if (PrintMiscellaneous && Verbose) { 933 warning("could not set shared memory file size: %s\n", strerror(errno)); 934 } 935 RESTARTABLE(::close(fd), result); 936 return -1; 937 } 938 939 return fd; 940} 941 942// open the shared memory file for the given user and vmid. returns 943// the file descriptor for the open file or -1 if the file could not 944// be opened. 945// 946static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 947 948 // open the file 949 int result; 950 // No O_NOFOLLOW defined at buildtime, and it is not documented for open; 951 // so provide a workaround in this case 952#ifdef O_NOFOLLOW 953 RESTARTABLE(::open(filename, oflags), result); 954#else 955 RESTARTABLE(::open_o_nofollow(filename, oflags), result); 956#endif 957 958 if (result == OS_ERR) { 959 if (errno == ENOENT) { 960 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 961 "Process not found"); 962 } 963 else if (errno == EACCES) { 964 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 965 "Permission denied"); 966 } 967 else { 968 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno)); 969 } 970 } 971 int fd = result; 972 973 // Check to see if the file is secure. 974 if (!is_file_secure(fd, filename)) { 975 ::close(fd); 976 return -1; 977 } 978 979 return fd; 980} 981 982// create a named shared memory region. returns the address of the 983// memory region on success or NULL on failure. A return value of 984// NULL will ultimately disable the shared memory feature. 985// 986// On Solaris and Linux, the name space for shared memory objects 987// is the file system name space. 988// 989// A monitoring application attaching to a JVM does not need to know 990// the file system name of the shared memory object. However, it may 991// be convenient for applications to discover the existence of newly 992// created and terminating JVMs by watching the file system name space 993// for files being created or removed. 994// 995static char* mmap_create_shared(size_t size) { 996 997 int result; 998 int fd; 999 char* mapAddress; 1000 1001 int vmid = os::current_process_id(); 1002 1003 char* user_name = get_user_name(geteuid()); 1004 1005 if (user_name == NULL) 1006 return NULL; 1007 1008 char* dirname = get_user_tmp_dir(user_name); 1009 char* filename = get_sharedmem_filename(dirname, vmid); 1010 1011 // Get the short filename. 1012 char* short_filename = strrchr(filename, '/'); 1013 if (short_filename == NULL) { 1014 short_filename = filename; 1015 } else { 1016 short_filename++; 1017 } 1018 1019 // cleanup any stale shared memory files 1020 cleanup_sharedmem_resources(dirname); 1021 1022 assert(((size > 0) && (size % os::vm_page_size() == 0)), 1023 "unexpected PerfMemory region size"); 1024 1025 fd = create_sharedmem_resources(dirname, short_filename, size); 1026 1027 FREE_C_HEAP_ARRAY(char, user_name); 1028 FREE_C_HEAP_ARRAY(char, dirname); 1029 1030 if (fd == -1) { 1031 FREE_C_HEAP_ARRAY(char, filename); 1032 return NULL; 1033 } 1034 1035 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 1036 1037 // attempt to close the file - restart it if it was interrupted, 1038 // but ignore other failures 1039 RESTARTABLE(::close(fd), result); 1040 assert(result != OS_ERR, "could not close file"); 1041 1042 if (mapAddress == MAP_FAILED) { 1043 if (PrintMiscellaneous && Verbose) { 1044 warning("mmap failed - %s\n", strerror(errno)); 1045 } 1046 remove_file(filename); 1047 FREE_C_HEAP_ARRAY(char, filename); 1048 return NULL; 1049 } 1050 1051 // save the file name for use in delete_shared_memory() 1052 backing_store_file_name = filename; 1053 1054 // clear the shared memory region 1055 (void)::memset((void*) mapAddress, 0, size); 1056 1057 // It does not go through os api, the operation has to record from here. 1058 MemTracker::record_virtual_memory_reserve((address)mapAddress, size, CURRENT_PC, mtInternal); 1059 1060 return mapAddress; 1061} 1062 1063// release a named shared memory region 1064// 1065static void unmap_shared(char* addr, size_t bytes) { 1066 // Do not rely on os::reserve_memory/os::release_memory to use mmap. 1067 // Use os::reserve_memory/os::release_memory for PerfDisableSharedMem=1, mmap/munmap for PerfDisableSharedMem=0 1068 if (::munmap(addr, bytes) == -1) { 1069 warning("perfmemory: munmap failed (%d)\n", errno); 1070 } 1071} 1072 1073// create the PerfData memory region in shared memory. 1074// 1075static char* create_shared_memory(size_t size) { 1076 1077 // create the shared memory region. 1078 return mmap_create_shared(size); 1079} 1080 1081// delete the shared PerfData memory region 1082// 1083static void delete_shared_memory(char* addr, size_t size) { 1084 1085 // cleanup the persistent shared memory resources. since DestroyJavaVM does 1086 // not support unloading of the JVM, unmapping of the memory resource is 1087 // not performed. The memory will be reclaimed by the OS upon termination of 1088 // the process. The backing store file is deleted from the file system. 1089 1090 assert(!PerfDisableSharedMem, "shouldn't be here"); 1091 1092 if (backing_store_file_name != NULL) { 1093 remove_file(backing_store_file_name); 1094 // Don't.. Free heap memory could deadlock os::abort() if it is called 1095 // from signal handler. OS will reclaim the heap memory. 1096 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 1097 backing_store_file_name = NULL; 1098 } 1099} 1100 1101// return the size of the file for the given file descriptor 1102// or 0 if it is not a valid size for a shared memory file 1103// 1104static size_t sharedmem_filesize(int fd, TRAPS) { 1105 1106 struct stat statbuf; 1107 int result; 1108 1109 RESTARTABLE(::fstat(fd, &statbuf), result); 1110 if (result == OS_ERR) { 1111 if (PrintMiscellaneous && Verbose) { 1112 warning("fstat failed: %s\n", strerror(errno)); 1113 } 1114 THROW_MSG_0(vmSymbols::java_io_IOException(), 1115 "Could not determine PerfMemory size"); 1116 } 1117 1118 if ((statbuf.st_size == 0) || 1119 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 1120 THROW_MSG_0(vmSymbols::java_lang_Exception(), 1121 "Invalid PerfMemory size"); 1122 } 1123 1124 return (size_t)statbuf.st_size; 1125} 1126 1127// attach to a named shared memory region. 1128// 1129static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 1130 1131 char* mapAddress; 1132 int result; 1133 int fd; 1134 size_t size = 0; 1135 const char* luser = NULL; 1136 1137 int mmap_prot; 1138 int file_flags; 1139 1140 ResourceMark rm; 1141 1142 // map the high level access mode to the appropriate permission 1143 // constructs for the file and the shared memory mapping. 1144 if (mode == PerfMemory::PERF_MODE_RO) { 1145 mmap_prot = PROT_READ; 1146 1147 // No O_NOFOLLOW defined at buildtime, and it is not documented for open. 1148#ifdef O_NOFOLLOW 1149 file_flags = O_RDONLY | O_NOFOLLOW; 1150#else 1151 file_flags = O_RDONLY; 1152#endif 1153 } 1154 else if (mode == PerfMemory::PERF_MODE_RW) { 1155#ifdef LATER 1156 mmap_prot = PROT_READ | PROT_WRITE; 1157 file_flags = O_RDWR | O_NOFOLLOW; 1158#else 1159 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1160 "Unsupported access mode"); 1161#endif 1162 } 1163 else { 1164 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1165 "Illegal access mode"); 1166 } 1167 1168 if (user == NULL || strlen(user) == 0) { 1169 luser = get_user_name(vmid, CHECK); 1170 } 1171 else { 1172 luser = user; 1173 } 1174 1175 if (luser == NULL) { 1176 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1177 "Could not map vmid to user Name"); 1178 } 1179 1180 char* dirname = get_user_tmp_dir(luser); 1181 1182 // since we don't follow symbolic links when creating the backing 1183 // store file, we don't follow them when attaching either. 1184 // 1185 if (!is_directory_secure(dirname)) { 1186 FREE_C_HEAP_ARRAY(char, dirname); 1187 if (luser != user) { 1188 FREE_C_HEAP_ARRAY(char, luser); 1189 } 1190 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1191 "Process not found"); 1192 } 1193 1194 char* filename = get_sharedmem_filename(dirname, vmid); 1195 1196 // copy heap memory to resource memory. the open_sharedmem_file 1197 // method below need to use the filename, but could throw an 1198 // exception. using a resource array prevents the leak that 1199 // would otherwise occur. 1200 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); 1201 strcpy(rfilename, filename); 1202 1203 // free the c heap resources that are no longer needed 1204 if (luser != user) FREE_C_HEAP_ARRAY(char, luser); 1205 FREE_C_HEAP_ARRAY(char, dirname); 1206 FREE_C_HEAP_ARRAY(char, filename); 1207 1208 // open the shared memory file for the give vmid 1209 fd = open_sharedmem_file(rfilename, file_flags, CHECK); 1210 assert(fd != OS_ERR, "unexpected value"); 1211 1212 if (*sizep == 0) { 1213 size = sharedmem_filesize(fd, CHECK); 1214 assert(size != 0, "unexpected size"); 1215 } else { 1216 size = *sizep; 1217 } 1218 1219 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 1220 1221 // attempt to close the file - restart if it gets interrupted, 1222 // but ignore other failures 1223 RESTARTABLE(::close(fd), result); 1224 assert(result != OS_ERR, "could not close file"); 1225 1226 if (mapAddress == MAP_FAILED) { 1227 if (PrintMiscellaneous && Verbose) { 1228 warning("mmap failed: %s\n", strerror(errno)); 1229 } 1230 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 1231 "Could not map PerfMemory"); 1232 } 1233 1234 // It does not go through os api, the operation has to record from here. 1235 MemTracker::record_virtual_memory_reserve((address)mapAddress, size, CURRENT_PC, mtInternal); 1236 1237 *addr = mapAddress; 1238 *sizep = size; 1239 1240 if (PerfTraceMemOps) { 1241 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at " 1242 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress); 1243 } 1244} 1245 1246 1247 1248 1249// create the PerfData memory region 1250// 1251// This method creates the memory region used to store performance 1252// data for the JVM. The memory may be created in standard or 1253// shared memory. 1254// 1255void PerfMemory::create_memory_region(size_t size) { 1256 1257 if (PerfDisableSharedMem) { 1258 // do not share the memory for the performance data. 1259 _start = create_standard_memory(size); 1260 } 1261 else { 1262 _start = create_shared_memory(size); 1263 if (_start == NULL) { 1264 1265 // creation of the shared memory region failed, attempt 1266 // to create a contiguous, non-shared memory region instead. 1267 // 1268 if (PrintMiscellaneous && Verbose) { 1269 warning("Reverting to non-shared PerfMemory region.\n"); 1270 } 1271 PerfDisableSharedMem = true; 1272 _start = create_standard_memory(size); 1273 } 1274 } 1275 1276 if (_start != NULL) _capacity = size; 1277 1278} 1279 1280// delete the PerfData memory region 1281// 1282// This method deletes the memory region used to store performance 1283// data for the JVM. The memory region indicated by the <address, size> 1284// tuple will be inaccessible after a call to this method. 1285// 1286void PerfMemory::delete_memory_region() { 1287 1288 assert((start() != NULL && capacity() > 0), "verify proper state"); 1289 1290 // If user specifies PerfDataSaveFile, it will save the performance data 1291 // to the specified file name no matter whether PerfDataSaveToFile is specified 1292 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 1293 // -XX:+PerfDataSaveToFile. 1294 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 1295 save_memory_to_file(start(), capacity()); 1296 } 1297 1298 if (PerfDisableSharedMem) { 1299 delete_standard_memory(start(), capacity()); 1300 } 1301 else { 1302 delete_shared_memory(start(), capacity()); 1303 } 1304} 1305 1306// attach to the PerfData memory region for another JVM 1307// 1308// This method returns an <address, size> tuple that points to 1309// a memory buffer that is kept reasonably synchronized with 1310// the PerfData memory region for the indicated JVM. This 1311// buffer may be kept in synchronization via shared memory 1312// or some other mechanism that keeps the buffer updated. 1313// 1314// If the JVM chooses not to support the attachability feature, 1315// this method should throw an UnsupportedOperation exception. 1316// 1317// This implementation utilizes named shared memory to map 1318// the indicated process's PerfData memory region into this JVMs 1319// address space. 1320// 1321void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1322 1323 if (vmid == 0 || vmid == os::current_process_id()) { 1324 *addrp = start(); 1325 *sizep = capacity(); 1326 return; 1327 } 1328 1329 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1330} 1331 1332// detach from the PerfData memory region of another JVM 1333// 1334// This method detaches the PerfData memory region of another 1335// JVM, specified as an <address, size> tuple of a buffer 1336// in this process's address space. This method may perform 1337// arbitrary actions to accomplish the detachment. The memory 1338// region specified by <address, size> will be inaccessible after 1339// a call to this method. 1340// 1341// If the JVM chooses not to support the attachability feature, 1342// this method should throw an UnsupportedOperation exception. 1343// 1344// This implementation utilizes named shared memory to detach 1345// the indicated process's PerfData memory region from this 1346// process's address space. 1347// 1348void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1349 1350 assert(addr != 0, "address sanity check"); 1351 assert(bytes > 0, "capacity sanity check"); 1352 1353 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1354 // prevent accidental detachment of this process's PerfMemory region 1355 return; 1356 } 1357 1358 unmap_shared(addr, bytes); 1359} 1360