perfMemory_aix.cpp revision 10874:de653b60a98e
1/* 2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved. 3 * Copyright (c) 2012, 2016 SAP SE. 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/os.hpp" 34#include "runtime/perfMemory.hpp" 35#include "services/memTracker.hpp" 36#include "utilities/exceptions.hpp" 37 38// put OS-includes here 39# include <sys/types.h> 40# include <sys/mman.h> 41# include <errno.h> 42# include <stdio.h> 43# include <unistd.h> 44# include <sys/stat.h> 45# include <signal.h> 46# include <pwd.h> 47 48static char* backing_store_file_name = NULL; // name of the backing store 49 // file, if successfully created. 50 51// Standard Memory Implementation Details 52 53// create the PerfData memory region in standard memory. 54// 55static char* create_standard_memory(size_t size) { 56 57 // allocate an aligned chuck of memory 58 char* mapAddress = os::reserve_memory(size); 59 60 if (mapAddress == NULL) { 61 return NULL; 62 } 63 64 // commit memory 65 if (!os::commit_memory(mapAddress, size, !ExecMem)) { 66 if (PrintMiscellaneous && Verbose) { 67 warning("Could not commit PerfData memory\n"); 68 } 69 os::release_memory(mapAddress, size); 70 return NULL; 71 } 72 73 return mapAddress; 74} 75 76// delete the PerfData memory region 77// 78static void delete_standard_memory(char* addr, size_t size) { 79 80 // there are no persistent external resources to cleanup for standard 81 // memory. since DestroyJavaVM does not support unloading of the JVM, 82 // cleanup of the memory resource is not performed. The memory will be 83 // reclaimed by the OS upon termination of the process. 84 // 85 return; 86} 87 88// save the specified memory region to the given file 89// 90// Note: this function might be called from signal handler (by os::abort()), 91// don't allocate heap memory. 92// 93static void save_memory_to_file(char* addr, size_t size) { 94 95 const char* destfile = PerfMemory::get_perfdata_file_path(); 96 assert(destfile[0] != '\0', "invalid PerfData file path"); 97 98 int result; 99 100 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), 101 result);; 102 if (result == OS_ERR) { 103 if (PrintMiscellaneous && Verbose) { 104 warning("Could not create Perfdata save file: %s: %s\n", 105 destfile, os::strerror(errno)); 106 } 107 } else { 108 int fd = result; 109 110 for (size_t remaining = size; remaining > 0;) { 111 112 RESTARTABLE(::write(fd, addr, remaining), result); 113 if (result == OS_ERR) { 114 if (PrintMiscellaneous && Verbose) { 115 warning("Could not write Perfdata save file: %s: %s\n", 116 destfile, os::strerror(errno)); 117 } 118 break; 119 } 120 121 remaining -= (size_t)result; 122 addr += result; 123 } 124 125 result = ::close(fd); 126 if (PrintMiscellaneous && Verbose) { 127 if (result == OS_ERR) { 128 warning("Could not close %s: %s\n", destfile, os::strerror(errno)); 129 } 130 } 131 } 132 FREE_C_HEAP_ARRAY(char, destfile); 133} 134 135 136// Shared Memory Implementation Details 137 138// Note: the solaris and linux shared memory implementation uses the mmap 139// interface with a backing store file to implement named shared memory. 140// Using the file system as the name space for shared memory allows a 141// common name space to be supported across a variety of platforms. It 142// also provides a name space that Java applications can deal with through 143// simple file apis. 144// 145// The solaris and linux implementations store the backing store file in 146// a user specific temporary directory located in the /tmp file system, 147// which is always a local file system and is sometimes a RAM based file 148// system. 149 150// return the user specific temporary directory name. 151// 152// the caller is expected to free the allocated memory. 153// 154static char* get_user_tmp_dir(const char* user) { 155 156 const char* tmpdir = os::get_temp_directory(); 157 const char* perfdir = PERFDATA_NAME; 158 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3; 159 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 160 161 // construct the path name to user specific tmp directory 162 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user); 163 164 return dirname; 165} 166 167// convert the given file name into a process id. if the file 168// does not meet the file naming constraints, return 0. 169// 170static pid_t filename_to_pid(const char* filename) { 171 172 // a filename that doesn't begin with a digit is not a 173 // candidate for conversion. 174 // 175 if (!isdigit(*filename)) { 176 return 0; 177 } 178 179 // check if file name can be converted to an integer without 180 // any leftover characters. 181 // 182 char* remainder = NULL; 183 errno = 0; 184 pid_t pid = (pid_t)strtol(filename, &remainder, 10); 185 186 if (errno != 0) { 187 return 0; 188 } 189 190 // check for left over characters. If any, then the filename is 191 // not a candidate for conversion. 192 // 193 if (remainder != NULL && *remainder != '\0') { 194 return 0; 195 } 196 197 // successful conversion, return the pid 198 return pid; 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// (Taken over from Solaris to support the O_NOFOLLOW case on AIX.) 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. 255static bool is_dirfd_secure(int dir_fd) { 256 struct stat statbuf; 257 int result = 0; 258 259 RESTARTABLE(::fstat(dir_fd, &statbuf), result); 260 if (result == OS_ERR) { 261 return false; 262 } 263 264 // The path exists, now check its mode. 265 return is_statbuf_secure(&statbuf); 266} 267 268 269// Check to make sure fd1 and fd2 are referencing the same file system object. 270static bool is_same_fsobject(int fd1, int fd2) { 271 struct stat statbuf1; 272 struct stat statbuf2; 273 int result = 0; 274 275 RESTARTABLE(::fstat(fd1, &statbuf1), result); 276 if (result == OS_ERR) { 277 return false; 278 } 279 RESTARTABLE(::fstat(fd2, &statbuf2), result); 280 if (result == OS_ERR) { 281 return false; 282 } 283 284 if ((statbuf1.st_ino == statbuf2.st_ino) && 285 (statbuf1.st_dev == statbuf2.st_dev)) { 286 return true; 287 } else { 288 return false; 289 } 290} 291 292// Helper functions for open without O_NOFOLLOW which is not present on AIX 5.3/6.1. 293// We use the jdk6 implementation here. 294#ifndef O_NOFOLLOW 295// The O_NOFOLLOW oflag doesn't exist before solaris 5.10, this is to simulate that behaviour 296// was done in jdk 5/6 hotspot by Oracle this way 297static int open_o_nofollow_impl(const char* path, int oflag, mode_t mode, bool use_mode) { 298 struct stat orig_st; 299 struct stat new_st; 300 bool create; 301 int error; 302 int fd; 303 int result; 304 305 create = false; 306 307 RESTARTABLE(::lstat(path, &orig_st), result); 308 309 if (result == OS_ERR) { 310 if (errno == ENOENT && (oflag & O_CREAT) != 0) { 311 // File doesn't exist, but_we want to create it, add O_EXCL flag 312 // to make sure no-one creates it (or a symlink) before us 313 // This works as we expect with symlinks, from posix man page: 314 // 'If O_EXCL and O_CREAT are set, and path names a symbolic 315 // link, open() shall fail and set errno to [EEXIST]'. 316 oflag |= O_EXCL; 317 create = true; 318 } else { 319 // File doesn't exist, and we are not creating it. 320 return OS_ERR; 321 } 322 } else { 323 // lstat success, check if existing file is a link. 324 if ((orig_st.st_mode & S_IFMT) == S_IFLNK) { 325 // File is a symlink. 326 errno = ELOOP; 327 return OS_ERR; 328 } 329 } 330 331 if (use_mode == true) { 332 RESTARTABLE(::open(path, oflag, mode), fd); 333 } else { 334 RESTARTABLE(::open(path, oflag), fd); 335 } 336 337 if (fd == OS_ERR) { 338 return fd; 339 } 340 341 // Can't do inode checks on before/after if we created the file. 342 if (create == false) { 343 RESTARTABLE(::fstat(fd, &new_st), result); 344 if (result == OS_ERR) { 345 // Keep errno from fstat, in case close also fails. 346 error = errno; 347 ::close(fd); 348 errno = error; 349 return OS_ERR; 350 } 351 352 if (orig_st.st_dev != new_st.st_dev || orig_st.st_ino != new_st.st_ino) { 353 // File was tampered with during race window. 354 ::close(fd); 355 errno = EEXIST; 356 if (PrintMiscellaneous && Verbose) { 357 warning("possible file tampering attempt detected when opening %s", path); 358 } 359 return OS_ERR; 360 } 361 } 362 363 return fd; 364} 365 366static int open_o_nofollow(const char* path, int oflag, mode_t mode) { 367 return open_o_nofollow_impl(path, oflag, mode, true); 368} 369 370static int open_o_nofollow(const char* path, int oflag) { 371 return open_o_nofollow_impl(path, oflag, 0, false); 372} 373#endif 374 375// Open the directory of the given path and validate it. 376// Return a DIR * of the open directory. 377static DIR *open_directory_secure(const char* dirname) { 378 // Open the directory using open() so that it can be verified 379 // to be secure by calling is_dirfd_secure(), opendir() and then check 380 // to see if they are the same file system object. This method does not 381 // introduce a window of opportunity for the directory to be attacked that 382 // calling opendir() and is_directory_secure() does. 383 int result; 384 DIR *dirp = NULL; 385 386 // No O_NOFOLLOW defined at buildtime, and it is not documented for open; 387 // so provide a workaround in this case. 388#ifdef O_NOFOLLOW 389 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result); 390#else 391 // workaround (jdk6 coding) 392 result = open_o_nofollow(dirname, O_RDONLY); 393#endif 394 395 if (result == OS_ERR) { 396 // Directory doesn't exist or is a symlink, so there is nothing to cleanup. 397 if (PrintMiscellaneous && Verbose) { 398 if (errno == ELOOP) { 399 warning("directory %s is a symlink and is not secure\n", dirname); 400 } else { 401 warning("could not open directory %s: %s\n", dirname, os::strerror(errno)); 402 } 403 } 404 return dirp; 405 } 406 int fd = result; 407 408 // Determine if the open directory is secure. 409 if (!is_dirfd_secure(fd)) { 410 // The directory is not a secure directory. 411 os::close(fd); 412 return dirp; 413 } 414 415 // Open the directory. 416 dirp = ::opendir(dirname); 417 if (dirp == NULL) { 418 // The directory doesn't exist, close fd and return. 419 os::close(fd); 420 return dirp; 421 } 422 423 // Check to make sure fd and dirp are referencing the same file system object. 424 if (!is_same_fsobject(fd, dirp->dd_fd)) { 425 // The directory is not secure. 426 os::close(fd); 427 os::closedir(dirp); 428 dirp = NULL; 429 return dirp; 430 } 431 432 // Close initial open now that we know directory is secure 433 os::close(fd); 434 435 return dirp; 436} 437 438// NOTE: The code below uses fchdir(), open() and unlink() because 439// fdopendir(), openat() and unlinkat() are not supported on all 440// versions. Once the support for fdopendir(), openat() and unlinkat() 441// is available on all supported versions the code can be changed 442// to use these functions. 443 444// Open the directory of the given path, validate it and set the 445// current working directory to it. 446// Return a DIR * of the open directory and the saved cwd fd. 447// 448static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) { 449 450 // Open the directory. 451 DIR* dirp = open_directory_secure(dirname); 452 if (dirp == NULL) { 453 // Directory doesn't exist or is insecure, so there is nothing to cleanup. 454 return dirp; 455 } 456 int fd = dirp->dd_fd; 457 458 // Open a fd to the cwd and save it off. 459 int result; 460 RESTARTABLE(::open(".", O_RDONLY), result); 461 if (result == OS_ERR) { 462 *saved_cwd_fd = -1; 463 } else { 464 *saved_cwd_fd = result; 465 } 466 467 // Set the current directory to dirname by using the fd of the directory and 468 // handle errors, otherwise shared memory files will be created in cwd. 469 result = fchdir(fd); 470 if (result == OS_ERR) { 471 if (PrintMiscellaneous && Verbose) { 472 warning("could not change to directory %s", dirname); 473 } 474 if (*saved_cwd_fd != -1) { 475 ::close(*saved_cwd_fd); 476 *saved_cwd_fd = -1; 477 } 478 // Close the directory. 479 os::closedir(dirp); 480 return NULL; 481 } else { 482 return dirp; 483 } 484} 485 486// Close the directory and restore the current working directory. 487// 488static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) { 489 490 int result; 491 // If we have a saved cwd change back to it and close the fd. 492 if (saved_cwd_fd != -1) { 493 result = fchdir(saved_cwd_fd); 494 ::close(saved_cwd_fd); 495 } 496 497 // Close the directory. 498 os::closedir(dirp); 499} 500 501// Check if the given file descriptor is considered a secure. 502static bool is_file_secure(int fd, const char *filename) { 503 504 int result; 505 struct stat statbuf; 506 507 // Determine if the file is secure. 508 RESTARTABLE(::fstat(fd, &statbuf), result); 509 if (result == OS_ERR) { 510 if (PrintMiscellaneous && Verbose) { 511 warning("fstat failed on %s: %s\n", filename, os::strerror(errno)); 512 } 513 return false; 514 } 515 if (statbuf.st_nlink > 1) { 516 // A file with multiple links is not expected. 517 if (PrintMiscellaneous && Verbose) { 518 warning("file %s has multiple links\n", filename); 519 } 520 return false; 521 } 522 return true; 523} 524 525// Return the user name for the given user id. 526// 527// The caller is expected to free the allocated memory. 528static char* get_user_name(uid_t uid) { 529 530 struct passwd pwent; 531 532 // Determine the max pwbuf size from sysconf, and hardcode 533 // a default if this not available through sysconf. 534 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); 535 if (bufsize == -1) 536 bufsize = 1024; 537 538 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 539 540 struct passwd* p; 541 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 542 543 if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 544 if (PrintMiscellaneous && Verbose) { 545 if (result != 0) { 546 warning("Could not retrieve passwd entry: %s\n", 547 os::strerror(result)); 548 } 549 else if (p == NULL) { 550 // this check is added to protect against an observed problem 551 // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0, 552 // indicating success, but has p == NULL. This was observed when 553 // inserting a file descriptor exhaustion fault prior to the call 554 // getpwuid_r() call. In this case, error is set to the appropriate 555 // error condition, but this is undocumented behavior. This check 556 // is safe under any condition, but the use of errno in the output 557 // message may result in an erroneous message. 558 // Bug Id 89052 was opened with RedHat. 559 // 560 warning("Could not retrieve passwd entry: %s\n", 561 os::strerror(errno)); 562 } 563 else { 564 warning("Could not determine user name: %s\n", 565 p->pw_name == NULL ? "pw_name = NULL" : 566 "pw_name zero length"); 567 } 568 } 569 FREE_C_HEAP_ARRAY(char, pwbuf); 570 return NULL; 571 } 572 573 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal); 574 strcpy(user_name, p->pw_name); 575 576 FREE_C_HEAP_ARRAY(char, pwbuf); 577 return user_name; 578} 579 580// return the name of the user that owns the process identified by vmid. 581// 582// This method uses a slow directory search algorithm to find the backing 583// store file for the specified vmid and returns the user name, as determined 584// by the user name suffix of the hsperfdata_<username> directory name. 585// 586// the caller is expected to free the allocated memory. 587// 588static char* get_user_name_slow(int vmid, TRAPS) { 589 590 // short circuit the directory search if the process doesn't even exist. 591 if (kill(vmid, 0) == OS_ERR) { 592 if (errno == ESRCH) { 593 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 594 "Process not found"); 595 } 596 else /* EPERM */ { 597 THROW_MSG_0(vmSymbols::java_io_IOException(), os::strerror(errno)); 598 } 599 } 600 601 // directory search 602 char* oldest_user = NULL; 603 time_t oldest_ctime = 0; 604 605 const char* tmpdirname = os::get_temp_directory(); 606 607 DIR* tmpdirp = os::opendir(tmpdirname); 608 609 if (tmpdirp == NULL) { 610 return NULL; 611 } 612 613 // for each entry in the directory that matches the pattern hsperfdata_*, 614 // open the directory and check if the file for the given vmid exists. 615 // The file with the expected name and the latest creation date is used 616 // to determine the user name for the process id. 617 // 618 struct dirent* dentry; 619 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal); 620 errno = 0; 621 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) { 622 623 // check if the directory entry is a hsperfdata file 624 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { 625 continue; 626 } 627 628 char* usrdir_name = NEW_C_HEAP_ARRAY(char, 629 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal); 630 strcpy(usrdir_name, tmpdirname); 631 strcat(usrdir_name, "/"); 632 strcat(usrdir_name, dentry->d_name); 633 634 // Open the user directory. 635 DIR* subdirp = open_directory_secure(usrdir_name); 636 637 if (subdirp == NULL) { 638 FREE_C_HEAP_ARRAY(char, usrdir_name); 639 continue; 640 } 641 642 // Since we don't create the backing store files in directories 643 // pointed to by symbolic links, we also don't follow them when 644 // looking for the files. We check for a symbolic link after the 645 // call to opendir in order to eliminate a small window where the 646 // symlink can be exploited. 647 // 648 if (!is_directory_secure(usrdir_name)) { 649 FREE_C_HEAP_ARRAY(char, usrdir_name); 650 os::closedir(subdirp); 651 continue; 652 } 653 654 struct dirent* udentry; 655 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal); 656 errno = 0; 657 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) { 658 659 if (filename_to_pid(udentry->d_name) == vmid) { 660 struct stat statbuf; 661 int result; 662 663 char* filename = NEW_C_HEAP_ARRAY(char, 664 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal); 665 666 strcpy(filename, usrdir_name); 667 strcat(filename, "/"); 668 strcat(filename, udentry->d_name); 669 670 // don't follow symbolic links for the file 671 RESTARTABLE(::lstat(filename, &statbuf), result); 672 if (result == OS_ERR) { 673 FREE_C_HEAP_ARRAY(char, filename); 674 continue; 675 } 676 677 // skip over files that are not regular files. 678 if (!S_ISREG(statbuf.st_mode)) { 679 FREE_C_HEAP_ARRAY(char, filename); 680 continue; 681 } 682 683 // compare and save filename with latest creation time 684 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { 685 686 if (statbuf.st_ctime > oldest_ctime) { 687 char* user = strchr(dentry->d_name, '_') + 1; 688 689 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user); 690 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal); 691 692 strcpy(oldest_user, user); 693 oldest_ctime = statbuf.st_ctime; 694 } 695 } 696 697 FREE_C_HEAP_ARRAY(char, filename); 698 } 699 } 700 os::closedir(subdirp); 701 FREE_C_HEAP_ARRAY(char, udbuf); 702 FREE_C_HEAP_ARRAY(char, usrdir_name); 703 } 704 os::closedir(tmpdirp); 705 FREE_C_HEAP_ARRAY(char, tdbuf); 706 707 return(oldest_user); 708} 709 710// return the name of the user that owns the JVM indicated by the given vmid. 711// 712static char* get_user_name(int vmid, TRAPS) { 713 return get_user_name_slow(vmid, THREAD); 714} 715 716// return the file name of the backing store file for the named 717// shared memory region for the given user name and vmid. 718// 719// the caller is expected to free the allocated memory. 720// 721static char* get_sharedmem_filename(const char* dirname, int vmid) { 722 723 // add 2 for the file separator and a null terminator. 724 size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 725 726 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 727 snprintf(name, nbytes, "%s/%d", dirname, vmid); 728 729 return name; 730} 731 732 733// remove file 734// 735// this method removes the file specified by the given path 736// 737static void remove_file(const char* path) { 738 739 int result; 740 741 // if the file is a directory, the following unlink will fail. since 742 // we don't expect to find directories in the user temp directory, we 743 // won't try to handle this situation. even if accidentially or 744 // maliciously planted, the directory's presence won't hurt anything. 745 // 746 RESTARTABLE(::unlink(path), result); 747 if (PrintMiscellaneous && Verbose && result == OS_ERR) { 748 if (errno != ENOENT) { 749 warning("Could not unlink shared memory backing" 750 " store file %s : %s\n", path, os::strerror(errno)); 751 } 752 } 753} 754 755// Cleanup stale shared memory resources 756// 757// This method attempts to remove all stale shared memory files in 758// the named user temporary directory. It scans the named directory 759// for files matching the pattern ^$[0-9]*$. For each file found, the 760// process id is extracted from the file name and a test is run to 761// determine if the process is alive. If the process is not alive, 762// any stale file resources are removed. 763static void cleanup_sharedmem_resources(const char* dirname) { 764 765 int saved_cwd_fd; 766 // Open the directory. 767 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 768 if (dirp == NULL) { 769 // Directory doesn't exist or is insecure, so there is nothing to cleanup. 770 return; 771 } 772 773 // For each entry in the directory that matches the expected file 774 // name pattern, determine if the file resources are stale and if 775 // so, remove the file resources. Note, instrumented HotSpot processes 776 // for this user may start and/or terminate during this search and 777 // remove or create new files in this directory. The behavior of this 778 // loop under these conditions is dependent upon the implementation of 779 // opendir/readdir. 780 struct dirent* entry; 781 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal); 782 783 errno = 0; 784 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) { 785 786 pid_t pid = filename_to_pid(entry->d_name); 787 788 if (pid == 0) { 789 790 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 791 792 // Attempt to remove all unexpected files, except "." and "..". 793 unlink(entry->d_name); 794 } 795 796 errno = 0; 797 continue; 798 } 799 800 // We now have a file name that converts to a valid integer 801 // that could represent a process id . if this process id 802 // matches the current process id or the process is not running, 803 // then remove the stale file resources. 804 // 805 // Process liveness is detected by sending signal number 0 to 806 // the process id (see kill(2)). if kill determines that the 807 // process does not exist, then the file resources are removed. 808 // if kill determines that that we don't have permission to 809 // signal the process, then the file resources are assumed to 810 // be stale and are removed because the resources for such a 811 // process should be in a different user specific directory. 812 if ((pid == os::current_process_id()) || 813 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 814 815 unlink(entry->d_name); 816 } 817 errno = 0; 818 } 819 820 // Close the directory and reset the current working directory. 821 close_directory_secure_cwd(dirp, saved_cwd_fd); 822 823 FREE_C_HEAP_ARRAY(char, dbuf); 824} 825 826// Make the user specific temporary directory. Returns true if 827// the directory exists and is secure upon return. Returns false 828// if the directory exists but is either a symlink, is otherwise 829// insecure, or if an error occurred. 830static bool make_user_tmp_dir(const char* dirname) { 831 832 // Create the directory with 0755 permissions. note that the directory 833 // will be owned by euid::egid, which may not be the same as uid::gid. 834 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 835 if (errno == EEXIST) { 836 // The directory already exists and was probably created by another 837 // JVM instance. However, this could also be the result of a 838 // deliberate symlink. Verify that the existing directory is safe. 839 if (!is_directory_secure(dirname)) { 840 // Directory is not secure. 841 if (PrintMiscellaneous && Verbose) { 842 warning("%s directory is insecure\n", dirname); 843 } 844 return false; 845 } 846 } 847 else { 848 // we encountered some other failure while attempting 849 // to create the directory 850 // 851 if (PrintMiscellaneous && Verbose) { 852 warning("could not create directory %s: %s\n", 853 dirname, os::strerror(errno)); 854 } 855 return false; 856 } 857 } 858 return true; 859} 860 861// create the shared memory file resources 862// 863// This method creates the shared memory file with the given size 864// This method also creates the user specific temporary directory, if 865// it does not yet exist. 866// 867static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 868 869 // make the user temporary directory 870 if (!make_user_tmp_dir(dirname)) { 871 // could not make/find the directory or the found directory 872 // was not secure 873 return -1; 874 } 875 876 int saved_cwd_fd; 877 // Open the directory and set the current working directory to it. 878 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 879 if (dirp == NULL) { 880 // Directory doesn't exist or is insecure, so cannot create shared 881 // memory file. 882 return -1; 883 } 884 885 // Open the filename in the current directory. 886 // Cannot use O_TRUNC here; truncation of an existing file has to happen 887 // after the is_file_secure() check below. 888 int result; 889 890 // No O_NOFOLLOW defined at buildtime, and it is not documented for open; 891 // so provide a workaround in this case. 892#ifdef O_NOFOLLOW 893 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result); 894#else 895 // workaround function (jdk6 code) 896 result = open_o_nofollow(filename, O_RDWR|O_CREAT, S_IREAD|S_IWRITE); 897#endif 898 899 if (result == OS_ERR) { 900 if (PrintMiscellaneous && Verbose) { 901 if (errno == ELOOP) { 902 warning("file %s is a symlink and is not secure\n", filename); 903 } else { 904 warning("could not create file %s: %s\n", filename, os::strerror(errno)); 905 } 906 } 907 // Close the directory and reset the current working directory. 908 close_directory_secure_cwd(dirp, saved_cwd_fd); 909 910 return -1; 911 } 912 // Close the directory and reset the current working directory. 913 close_directory_secure_cwd(dirp, saved_cwd_fd); 914 915 // save the file descriptor 916 int fd = result; 917 918 // Check to see if the file is secure. 919 if (!is_file_secure(fd, filename)) { 920 ::close(fd); 921 return -1; 922 } 923 924 // Truncate the file to get rid of any existing data. 925 RESTARTABLE(::ftruncate(fd, (off_t)0), result); 926 if (result == OS_ERR) { 927 if (PrintMiscellaneous && Verbose) { 928 warning("could not truncate shared memory file: %s\n", os::strerror(errno)); 929 } 930 ::close(fd); 931 return -1; 932 } 933 // set the file size 934 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 935 if (result == OS_ERR) { 936 if (PrintMiscellaneous && Verbose) { 937 warning("could not set shared memory file size: %s\n", os::strerror(errno)); 938 } 939 ::close(fd); 940 return -1; 941 } 942 943 return fd; 944} 945 946// open the shared memory file for the given user and vmid. returns 947// the file descriptor for the open file or -1 if the file could not 948// be opened. 949// 950static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 951 952 // open the file 953 int result; 954 // No O_NOFOLLOW defined at buildtime, and it is not documented for open; 955 // so provide a workaround in this case 956#ifdef O_NOFOLLOW 957 RESTARTABLE(::open(filename, oflags), result); 958#else 959 result = open_o_nofollow(filename, oflags); 960#endif 961 962 if (result == OS_ERR) { 963 if (errno == ENOENT) { 964 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 965 "Process not found"); 966 } 967 else if (errno == EACCES) { 968 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 969 "Permission denied"); 970 } 971 else { 972 THROW_MSG_0(vmSymbols::java_io_IOException(), os::strerror(errno)); 973 } 974 } 975 int fd = result; 976 977 // Check to see if the file is secure. 978 if (!is_file_secure(fd, filename)) { 979 ::close(fd); 980 return -1; 981 } 982 983 return fd; 984} 985 986// create a named shared memory region. returns the address of the 987// memory region on success or NULL on failure. A return value of 988// NULL will ultimately disable the shared memory feature. 989// 990// On AIX, Solaris and Linux, the name space for shared memory objects 991// is the file system name space. 992// 993// A monitoring application attaching to a JVM does not need to know 994// the file system name of the shared memory object. However, it may 995// be convenient for applications to discover the existence of newly 996// created and terminating JVMs by watching the file system name space 997// for files being created or removed. 998// 999static char* mmap_create_shared(size_t size) { 1000 1001 int result; 1002 int fd; 1003 char* mapAddress; 1004 1005 int vmid = os::current_process_id(); 1006 1007 char* user_name = get_user_name(geteuid()); 1008 1009 if (user_name == NULL) 1010 return NULL; 1011 1012 char* dirname = get_user_tmp_dir(user_name); 1013 char* filename = get_sharedmem_filename(dirname, vmid); 1014 // get the short filename. 1015 char* short_filename = strrchr(filename, '/'); 1016 if (short_filename == NULL) { 1017 short_filename = filename; 1018 } else { 1019 short_filename++; 1020 } 1021 1022 // cleanup any stale shared memory files 1023 cleanup_sharedmem_resources(dirname); 1024 1025 assert(((size > 0) && (size % os::vm_page_size() == 0)), 1026 "unexpected PerfMemory region size"); 1027 1028 fd = create_sharedmem_resources(dirname, short_filename, size); 1029 1030 FREE_C_HEAP_ARRAY(char, user_name); 1031 FREE_C_HEAP_ARRAY(char, dirname); 1032 1033 if (fd == -1) { 1034 FREE_C_HEAP_ARRAY(char, filename); 1035 return NULL; 1036 } 1037 1038 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 1039 1040 result = ::close(fd); 1041 assert(result != OS_ERR, "could not close file"); 1042 1043 if (mapAddress == MAP_FAILED) { 1044 if (PrintMiscellaneous && Verbose) { 1045 warning("mmap failed - %s\n", os::strerror(errno)); 1046 } 1047 remove_file(filename); 1048 FREE_C_HEAP_ARRAY(char, filename); 1049 return NULL; 1050 } 1051 1052 // save the file name for use in delete_shared_memory() 1053 backing_store_file_name = filename; 1054 1055 // clear the shared memory region 1056 (void)::memset((void*) mapAddress, 0, size); 1057 1058 // It does not go through os api, the operation has to record from here. 1059 MemTracker::record_virtual_memory_reserve((address)mapAddress, size, CURRENT_PC, mtInternal); 1060 1061 return mapAddress; 1062} 1063 1064// release a named shared memory region 1065// 1066static void unmap_shared(char* addr, size_t bytes) { 1067 // Do not rely on os::reserve_memory/os::release_memory to use mmap. 1068 // Use os::reserve_memory/os::release_memory for PerfDisableSharedMem=1, mmap/munmap for PerfDisableSharedMem=0 1069 if (::munmap(addr, bytes) == -1) { 1070 warning("perfmemory: munmap failed (%d)\n", errno); 1071 } 1072} 1073 1074// create the PerfData memory region in shared memory. 1075// 1076static char* create_shared_memory(size_t size) { 1077 1078 // create the shared memory region. 1079 return mmap_create_shared(size); 1080} 1081 1082// delete the shared PerfData memory region 1083// 1084static void delete_shared_memory(char* addr, size_t size) { 1085 1086 // cleanup the persistent shared memory resources. since DestroyJavaVM does 1087 // not support unloading of the JVM, unmapping of the memory resource is 1088 // not performed. The memory will be reclaimed by the OS upon termination of 1089 // the process. The backing store file is deleted from the file system. 1090 1091 assert(!PerfDisableSharedMem, "shouldn't be here"); 1092 1093 if (backing_store_file_name != NULL) { 1094 remove_file(backing_store_file_name); 1095 // Don't.. Free heap memory could deadlock os::abort() if it is called 1096 // from signal handler. OS will reclaim the heap memory. 1097 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 1098 backing_store_file_name = NULL; 1099 } 1100} 1101 1102// return the size of the file for the given file descriptor 1103// or 0 if it is not a valid size for a shared memory file 1104// 1105static size_t sharedmem_filesize(int fd, TRAPS) { 1106 1107 struct stat statbuf; 1108 int result; 1109 1110 RESTARTABLE(::fstat(fd, &statbuf), result); 1111 if (result == OS_ERR) { 1112 if (PrintMiscellaneous && Verbose) { 1113 warning("fstat failed: %s\n", os::strerror(errno)); 1114 } 1115 THROW_MSG_0(vmSymbols::java_io_IOException(), 1116 "Could not determine PerfMemory size"); 1117 } 1118 1119 if ((statbuf.st_size == 0) || 1120 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 1121 THROW_MSG_0(vmSymbols::java_lang_Exception(), 1122 "Invalid PerfMemory size"); 1123 } 1124 1125 return (size_t)statbuf.st_size; 1126} 1127 1128// attach to a named shared memory region. 1129// 1130static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 1131 1132 char* mapAddress; 1133 int result; 1134 int fd; 1135 size_t size = 0; 1136 const char* luser = NULL; 1137 1138 int mmap_prot; 1139 int file_flags; 1140 1141 ResourceMark rm; 1142 1143 // map the high level access mode to the appropriate permission 1144 // constructs for the file and the shared memory mapping. 1145 if (mode == PerfMemory::PERF_MODE_RO) { 1146 mmap_prot = PROT_READ; 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, THREAD); 1210 1211 if (fd == OS_ERR) { 1212 return; 1213 } 1214 1215 if (HAS_PENDING_EXCEPTION) { 1216 ::close(fd); 1217 return; 1218 } 1219 1220 if (*sizep == 0) { 1221 size = sharedmem_filesize(fd, CHECK); 1222 } else { 1223 size = *sizep; 1224 } 1225 1226 assert(size > 0, "unexpected size <= 0"); 1227 1228 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 1229 1230 result = ::close(fd); 1231 assert(result != OS_ERR, "could not close file"); 1232 1233 if (mapAddress == MAP_FAILED) { 1234 if (PrintMiscellaneous && Verbose) { 1235 warning("mmap failed: %s\n", os::strerror(errno)); 1236 } 1237 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 1238 "Could not map PerfMemory"); 1239 } 1240 1241 // it does not go through os api, the operation has to record from here. 1242 MemTracker::record_virtual_memory_reserve((address)mapAddress, size, CURRENT_PC, mtInternal); 1243 1244 *addr = mapAddress; 1245 *sizep = size; 1246 1247 if (PerfTraceMemOps) { 1248 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at " 1249 INTPTR_FORMAT "\n", size, vmid, p2i((void*)mapAddress)); 1250 } 1251} 1252 1253 1254 1255 1256// create the PerfData memory region 1257// 1258// This method creates the memory region used to store performance 1259// data for the JVM. The memory may be created in standard or 1260// shared memory. 1261// 1262void PerfMemory::create_memory_region(size_t size) { 1263 1264 if (PerfDisableSharedMem) { 1265 // do not share the memory for the performance data. 1266 _start = create_standard_memory(size); 1267 } 1268 else { 1269 _start = create_shared_memory(size); 1270 if (_start == NULL) { 1271 1272 // creation of the shared memory region failed, attempt 1273 // to create a contiguous, non-shared memory region instead. 1274 // 1275 if (PrintMiscellaneous && Verbose) { 1276 warning("Reverting to non-shared PerfMemory region.\n"); 1277 } 1278 PerfDisableSharedMem = true; 1279 _start = create_standard_memory(size); 1280 } 1281 } 1282 1283 if (_start != NULL) _capacity = size; 1284 1285} 1286 1287// delete the PerfData memory region 1288// 1289// This method deletes the memory region used to store performance 1290// data for the JVM. The memory region indicated by the <address, size> 1291// tuple will be inaccessible after a call to this method. 1292// 1293void PerfMemory::delete_memory_region() { 1294 1295 assert((start() != NULL && capacity() > 0), "verify proper state"); 1296 1297 // If user specifies PerfDataSaveFile, it will save the performance data 1298 // to the specified file name no matter whether PerfDataSaveToFile is specified 1299 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 1300 // -XX:+PerfDataSaveToFile. 1301 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 1302 save_memory_to_file(start(), capacity()); 1303 } 1304 1305 if (PerfDisableSharedMem) { 1306 delete_standard_memory(start(), capacity()); 1307 } 1308 else { 1309 delete_shared_memory(start(), capacity()); 1310 } 1311} 1312 1313// attach to the PerfData memory region for another JVM 1314// 1315// This method returns an <address, size> tuple that points to 1316// a memory buffer that is kept reasonably synchronized with 1317// the PerfData memory region for the indicated JVM. This 1318// buffer may be kept in synchronization via shared memory 1319// or some other mechanism that keeps the buffer updated. 1320// 1321// If the JVM chooses not to support the attachability feature, 1322// this method should throw an UnsupportedOperation exception. 1323// 1324// This implementation utilizes named shared memory to map 1325// the indicated process's PerfData memory region into this JVMs 1326// address space. 1327// 1328void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1329 1330 if (vmid == 0 || vmid == os::current_process_id()) { 1331 *addrp = start(); 1332 *sizep = capacity(); 1333 return; 1334 } 1335 1336 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1337} 1338 1339// detach from the PerfData memory region of another JVM 1340// 1341// This method detaches the PerfData memory region of another 1342// JVM, specified as an <address, size> tuple of a buffer 1343// in this process's address space. This method may perform 1344// arbitrary actions to accomplish the detachment. The memory 1345// region specified by <address, size> will be inaccessible after 1346// a call to this method. 1347// 1348// If the JVM chooses not to support the attachability feature, 1349// this method should throw an UnsupportedOperation exception. 1350// 1351// This implementation utilizes named shared memory to detach 1352// the indicated process's PerfData memory region from this 1353// process's address space. 1354// 1355void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1356 1357 assert(addr != 0, "address sanity check"); 1358 assert(bytes > 0, "capacity sanity check"); 1359 1360 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1361 // prevent accidental detachment of this process's PerfMemory region 1362 return; 1363 } 1364 1365 unmap_shared(addr, bytes); 1366} 1367