1/* 2 * Copyright (c) 2001, 2017, 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 "logging/log.hpp" 29#include "memory/allocation.inline.hpp" 30#include "memory/resourceArea.hpp" 31#include "oops/oop.inline.hpp" 32#include "os_aix.inline.hpp" 33#include "runtime/handles.inline.hpp" 34#include "runtime/os.hpp" 35#include "runtime/perfMemory.hpp" 36#include "services/memTracker.hpp" 37#include "utilities/exceptions.hpp" 38 39// put OS-includes here 40# include <sys/types.h> 41# include <sys/mman.h> 42# include <errno.h> 43# include <stdio.h> 44# include <unistd.h> 45# include <sys/stat.h> 46# include <signal.h> 47# include <pwd.h> 48 49static char* backing_store_file_name = NULL; // name of the backing store 50 // file, if successfully created. 51 52// Standard Memory Implementation Details 53 54// create the PerfData memory region in standard memory. 55// 56static char* create_standard_memory(size_t size) { 57 58 // allocate an aligned chuck of memory 59 char* mapAddress = os::reserve_memory(size); 60 61 if (mapAddress == NULL) { 62 return NULL; 63 } 64 65 // commit memory 66 if (!os::commit_memory(mapAddress, size, !ExecMem)) { 67 if (PrintMiscellaneous && Verbose) { 68 warning("Could not commit PerfData memory\n"); 69 } 70 os::release_memory(mapAddress, size); 71 return NULL; 72 } 73 74 return mapAddress; 75} 76 77// delete the PerfData memory region 78// 79static void delete_standard_memory(char* addr, size_t size) { 80 81 // there are no persistent external resources to cleanup for standard 82 // memory. since DestroyJavaVM does not support unloading of the JVM, 83 // cleanup of the memory resource is not performed. The memory will be 84 // reclaimed by the OS upon termination of the process. 85 // 86 return; 87} 88 89// save the specified memory region to the given file 90// 91// Note: this function might be called from signal handler (by os::abort()), 92// don't allocate heap memory. 93// 94static void save_memory_to_file(char* addr, size_t size) { 95 96 const char* destfile = PerfMemory::get_perfdata_file_path(); 97 assert(destfile[0] != '\0', "invalid PerfData file path"); 98 99 int result; 100 101 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), 102 result);; 103 if (result == OS_ERR) { 104 if (PrintMiscellaneous && Verbose) { 105 warning("Could not create Perfdata save file: %s: %s\n", 106 destfile, os::strerror(errno)); 107 } 108 } else { 109 int fd = result; 110 111 for (size_t remaining = size; remaining > 0;) { 112 113 RESTARTABLE(::write(fd, addr, remaining), result); 114 if (result == OS_ERR) { 115 if (PrintMiscellaneous && Verbose) { 116 warning("Could not write Perfdata save file: %s: %s\n", 117 destfile, os::strerror(errno)); 118 } 119 break; 120 } 121 122 remaining -= (size_t)result; 123 addr += result; 124 } 125 126 result = ::close(fd); 127 if (PrintMiscellaneous && Verbose) { 128 if (result == OS_ERR) { 129 warning("Could not close %s: %s\n", destfile, os::strerror(errno)); 130 } 131 } 132 } 133 FREE_C_HEAP_ARRAY(char, destfile); 134} 135 136 137// Shared Memory Implementation Details 138 139// Note: the solaris and linux shared memory implementation uses the mmap 140// interface with a backing store file to implement named shared memory. 141// Using the file system as the name space for shared memory allows a 142// common name space to be supported across a variety of platforms. It 143// also provides a name space that Java applications can deal with through 144// simple file apis. 145// 146// The solaris and linux implementations store the backing store file in 147// a user specific temporary directory located in the /tmp file system, 148// which is always a local file system and is sometimes a RAM based file 149// system. 150 151// return the user specific temporary directory name. 152// 153// the caller is expected to free the allocated memory. 154// 155static char* get_user_tmp_dir(const char* user) { 156 157 const char* tmpdir = os::get_temp_directory(); 158 const char* perfdir = PERFDATA_NAME; 159 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3; 160 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 161 162 // construct the path name to user specific tmp directory 163 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user); 164 165 return dirname; 166} 167 168// convert the given file name into a process id. if the file 169// does not meet the file naming constraints, return 0. 170// 171static pid_t filename_to_pid(const char* filename) { 172 173 // a filename that doesn't begin with a digit is not a 174 // candidate for conversion. 175 // 176 if (!isdigit(*filename)) { 177 return 0; 178 } 179 180 // check if file name can be converted to an integer without 181 // any leftover characters. 182 // 183 char* remainder = NULL; 184 errno = 0; 185 pid_t pid = (pid_t)strtol(filename, &remainder, 10); 186 187 if (errno != 0) { 188 return 0; 189 } 190 191 // check for left over characters. If any, then the filename is 192 // not a candidate for conversion. 193 // 194 if (remainder != NULL && *remainder != '\0') { 195 return 0; 196 } 197 198 // successful conversion, return the pid 199 return pid; 200} 201 202// Check if the given statbuf is considered a secure directory for 203// the backing store files. Returns true if the directory is considered 204// a secure location. Returns false if the statbuf is a symbolic link or 205// if an error occurred. 206// 207static bool is_statbuf_secure(struct stat *statp) { 208 if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) { 209 // The path represents a link or some non-directory file type, 210 // which is not what we expected. Declare it insecure. 211 // 212 return false; 213 } 214 // We have an existing directory, check if the permissions are safe. 215 // 216 if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) { 217 // The directory is open for writing and could be subjected 218 // to a symlink or a hard link attack. Declare it insecure. 219 // 220 return false; 221 } 222 // If user is not root then see if the uid of the directory matches the effective uid of the process. 223 uid_t euid = geteuid(); 224 if ((euid != 0) && (statp->st_uid != euid)) { 225 // The directory was not created by this user, declare it insecure. 226 // 227 return false; 228 } 229 return true; 230} 231 232 233// Check if the given path is considered a secure directory for 234// the backing store files. Returns true if the directory exists 235// and is considered a secure location. Returns false if the path 236// is a symbolic link or if an error occurred. 237// 238static bool is_directory_secure(const char* path) { 239 struct stat statbuf; 240 int result = 0; 241 242 RESTARTABLE(::lstat(path, &statbuf), result); 243 if (result == OS_ERR) { 244 return false; 245 } 246 247 // The path exists, see if it is secure. 248 return is_statbuf_secure(&statbuf); 249} 250 251// (Taken over from Solaris to support the O_NOFOLLOW case on AIX.) 252// Check if the given directory file descriptor is considered a secure 253// directory for the backing store files. Returns true if the directory 254// exists and is considered a secure location. Returns false if the path 255// is a symbolic link or if an error occurred. 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. 271static bool is_same_fsobject(int fd1, int fd2) { 272 struct stat statbuf1; 273 struct stat statbuf2; 274 int result = 0; 275 276 RESTARTABLE(::fstat(fd1, &statbuf1), result); 277 if (result == OS_ERR) { 278 return false; 279 } 280 RESTARTABLE(::fstat(fd2, &statbuf2), result); 281 if (result == OS_ERR) { 282 return false; 283 } 284 285 if ((statbuf1.st_ino == statbuf2.st_ino) && 286 (statbuf1.st_dev == statbuf2.st_dev)) { 287 return true; 288 } else { 289 return false; 290 } 291} 292 293// Helper functions for open without O_NOFOLLOW which is not present on AIX 5.3/6.1. 294// We use the jdk6 implementation here. 295#ifndef O_NOFOLLOW 296// The O_NOFOLLOW oflag doesn't exist before solaris 5.10, this is to simulate that behaviour 297// was done in jdk 5/6 hotspot by Oracle this way 298static int open_o_nofollow_impl(const char* path, int oflag, mode_t mode, bool use_mode) { 299 struct stat orig_st; 300 struct stat new_st; 301 bool create; 302 int error; 303 int fd; 304 int result; 305 306 create = false; 307 308 RESTARTABLE(::lstat(path, &orig_st), result); 309 310 if (result == OS_ERR) { 311 if (errno == ENOENT && (oflag & O_CREAT) != 0) { 312 // File doesn't exist, but_we want to create it, add O_EXCL flag 313 // to make sure no-one creates it (or a symlink) before us 314 // This works as we expect with symlinks, from posix man page: 315 // 'If O_EXCL and O_CREAT are set, and path names a symbolic 316 // link, open() shall fail and set errno to [EEXIST]'. 317 oflag |= O_EXCL; 318 create = true; 319 } else { 320 // File doesn't exist, and we are not creating it. 321 return OS_ERR; 322 } 323 } else { 324 // lstat success, check if existing file is a link. 325 if ((orig_st.st_mode & S_IFMT) == S_IFLNK) { 326 // File is a symlink. 327 errno = ELOOP; 328 return OS_ERR; 329 } 330 } 331 332 if (use_mode == true) { 333 RESTARTABLE(::open(path, oflag, mode), fd); 334 } else { 335 RESTARTABLE(::open(path, oflag), fd); 336 } 337 338 if (fd == OS_ERR) { 339 return fd; 340 } 341 342 // Can't do inode checks on before/after if we created the file. 343 if (create == false) { 344 RESTARTABLE(::fstat(fd, &new_st), result); 345 if (result == OS_ERR) { 346 // Keep errno from fstat, in case close also fails. 347 error = errno; 348 ::close(fd); 349 errno = error; 350 return OS_ERR; 351 } 352 353 if (orig_st.st_dev != new_st.st_dev || orig_st.st_ino != new_st.st_ino) { 354 // File was tampered with during race window. 355 ::close(fd); 356 errno = EEXIST; 357 if (PrintMiscellaneous && Verbose) { 358 warning("possible file tampering attempt detected when opening %s", path); 359 } 360 return OS_ERR; 361 } 362 } 363 364 return fd; 365} 366 367static int open_o_nofollow(const char* path, int oflag, mode_t mode) { 368 return open_o_nofollow_impl(path, oflag, mode, true); 369} 370 371static int open_o_nofollow(const char* path, int oflag) { 372 return open_o_nofollow_impl(path, oflag, 0, false); 373} 374#endif 375 376// Open the directory of the given path and validate it. 377// Return a DIR * of the open directory. 378static DIR *open_directory_secure(const char* dirname) { 379 // Open the directory using open() so that it can be verified 380 // to be secure by calling is_dirfd_secure(), opendir() and then check 381 // to see if they are the same file system object. This method does not 382 // introduce a window of opportunity for the directory to be attacked that 383 // calling opendir() and is_directory_secure() does. 384 int result; 385 DIR *dirp = NULL; 386 387 // No O_NOFOLLOW defined at buildtime, and it is not documented for open; 388 // so provide a workaround in this case. 389#ifdef O_NOFOLLOW 390 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result); 391#else 392 // workaround (jdk6 coding) 393 result = open_o_nofollow(dirname, O_RDONLY); 394#endif 395 396 if (result == OS_ERR) { 397 // Directory doesn't exist or is a symlink, so there is nothing to cleanup. 398 if (PrintMiscellaneous && Verbose) { 399 if (errno == ELOOP) { 400 warning("directory %s is a symlink and is not secure\n", dirname); 401 } else { 402 warning("could not open directory %s: %s\n", dirname, os::strerror(errno)); 403 } 404 } 405 return dirp; 406 } 407 int fd = result; 408 409 // Determine if the open directory is secure. 410 if (!is_dirfd_secure(fd)) { 411 // The directory is not a secure directory. 412 os::close(fd); 413 return dirp; 414 } 415 416 // Open the directory. 417 dirp = ::opendir(dirname); 418 if (dirp == NULL) { 419 // The directory doesn't exist, close fd and return. 420 os::close(fd); 421 return dirp; 422 } 423 424 // Check to make sure fd and dirp are referencing the same file system object. 425 if (!is_same_fsobject(fd, dirp->dd_fd)) { 426 // The directory is not secure. 427 os::close(fd); 428 os::closedir(dirp); 429 dirp = NULL; 430 return dirp; 431 } 432 433 // Close initial open now that we know directory is secure 434 os::close(fd); 435 436 return dirp; 437} 438 439// NOTE: The code below uses fchdir(), open() and unlink() because 440// fdopendir(), openat() and unlinkat() are not supported on all 441// versions. Once the support for fdopendir(), openat() and unlinkat() 442// is available on all supported versions the code can be changed 443// to use these functions. 444 445// Open the directory of the given path, validate it and set the 446// current working directory to it. 447// Return a DIR * of the open directory and the saved cwd fd. 448// 449static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) { 450 451 // Open the directory. 452 DIR* dirp = open_directory_secure(dirname); 453 if (dirp == NULL) { 454 // Directory doesn't exist or is insecure, so there is nothing to cleanup. 455 return dirp; 456 } 457 int fd = dirp->dd_fd; 458 459 // Open a fd to the cwd and save it off. 460 int result; 461 RESTARTABLE(::open(".", O_RDONLY), result); 462 if (result == OS_ERR) { 463 *saved_cwd_fd = -1; 464 } else { 465 *saved_cwd_fd = result; 466 } 467 468 // Set the current directory to dirname by using the fd of the directory and 469 // handle errors, otherwise shared memory files will be created in cwd. 470 result = fchdir(fd); 471 if (result == OS_ERR) { 472 if (PrintMiscellaneous && Verbose) { 473 warning("could not change to directory %s", dirname); 474 } 475 if (*saved_cwd_fd != -1) { 476 ::close(*saved_cwd_fd); 477 *saved_cwd_fd = -1; 478 } 479 // Close the directory. 480 os::closedir(dirp); 481 return NULL; 482 } else { 483 return dirp; 484 } 485} 486 487// Close the directory and restore the current working directory. 488// 489static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) { 490 491 int result; 492 // If we have a saved cwd change back to it and close the fd. 493 if (saved_cwd_fd != -1) { 494 result = fchdir(saved_cwd_fd); 495 ::close(saved_cwd_fd); 496 } 497 498 // Close the directory. 499 os::closedir(dirp); 500} 501 502// Check if the given file descriptor is considered a secure. 503static bool is_file_secure(int fd, const char *filename) { 504 505 int result; 506 struct stat statbuf; 507 508 // Determine if the file is secure. 509 RESTARTABLE(::fstat(fd, &statbuf), result); 510 if (result == OS_ERR) { 511 if (PrintMiscellaneous && Verbose) { 512 warning("fstat failed on %s: %s\n", filename, os::strerror(errno)); 513 } 514 return false; 515 } 516 if (statbuf.st_nlink > 1) { 517 // A file with multiple links is not expected. 518 if (PrintMiscellaneous && Verbose) { 519 warning("file %s has multiple links\n", filename); 520 } 521 return false; 522 } 523 return true; 524} 525 526// Return the user name for the given user id. 527// 528// The caller is expected to free the allocated memory. 529static char* get_user_name(uid_t uid) { 530 531 struct passwd pwent; 532 533 // Determine the max pwbuf size from sysconf, and hardcode 534 // a default if this not available through sysconf. 535 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); 536 if (bufsize == -1) 537 bufsize = 1024; 538 539 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 540 541 struct passwd* p; 542 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 543 544 if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 545 if (PrintMiscellaneous && Verbose) { 546 if (result != 0) { 547 warning("Could not retrieve passwd entry: %s\n", 548 os::strerror(result)); 549 } 550 else if (p == NULL) { 551 // this check is added to protect against an observed problem 552 // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0, 553 // indicating success, but has p == NULL. This was observed when 554 // inserting a file descriptor exhaustion fault prior to the call 555 // getpwuid_r() call. In this case, error is set to the appropriate 556 // error condition, but this is undocumented behavior. This check 557 // is safe under any condition, but the use of errno in the output 558 // message may result in an erroneous message. 559 // Bug Id 89052 was opened with RedHat. 560 // 561 warning("Could not retrieve passwd entry: %s\n", 562 os::strerror(errno)); 563 } 564 else { 565 warning("Could not determine user name: %s\n", 566 p->pw_name == NULL ? "pw_name = NULL" : 567 "pw_name zero length"); 568 } 569 } 570 FREE_C_HEAP_ARRAY(char, pwbuf); 571 return NULL; 572 } 573 574 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal); 575 strcpy(user_name, p->pw_name); 576 577 FREE_C_HEAP_ARRAY(char, pwbuf); 578 return user_name; 579} 580 581// return the name of the user that owns the process identified by vmid. 582// 583// This method uses a slow directory search algorithm to find the backing 584// store file for the specified vmid and returns the user name, as determined 585// by the user name suffix of the hsperfdata_<username> directory name. 586// 587// the caller is expected to free the allocated memory. 588// 589static char* get_user_name_slow(int vmid, TRAPS) { 590 591 // short circuit the directory search if the process doesn't even exist. 592 if (kill(vmid, 0) == OS_ERR) { 593 if (errno == ESRCH) { 594 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 595 "Process not found"); 596 } 597 else /* EPERM */ { 598 THROW_MSG_0(vmSymbols::java_io_IOException(), os::strerror(errno)); 599 } 600 } 601 602 // directory search 603 char* oldest_user = NULL; 604 time_t oldest_ctime = 0; 605 606 const char* tmpdirname = os::get_temp_directory(); 607 608 DIR* tmpdirp = os::opendir(tmpdirname); 609 610 if (tmpdirp == NULL) { 611 return NULL; 612 } 613 614 // for each entry in the directory that matches the pattern hsperfdata_*, 615 // open the directory and check if the file for the given vmid exists. 616 // The file with the expected name and the latest creation date is used 617 // to determine the user name for the process id. 618 // 619 struct dirent* dentry; 620 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal); 621 errno = 0; 622 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) { 623 624 // check if the directory entry is a hsperfdata file 625 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { 626 continue; 627 } 628 629 char* usrdir_name = NEW_C_HEAP_ARRAY(char, 630 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal); 631 strcpy(usrdir_name, tmpdirname); 632 strcat(usrdir_name, "/"); 633 strcat(usrdir_name, dentry->d_name); 634 635 // Open the user directory. 636 DIR* subdirp = open_directory_secure(usrdir_name); 637 638 if (subdirp == NULL) { 639 FREE_C_HEAP_ARRAY(char, usrdir_name); 640 continue; 641 } 642 643 // Since we don't create the backing store files in directories 644 // pointed to by symbolic links, we also don't follow them when 645 // looking for the files. We check for a symbolic link after the 646 // call to opendir in order to eliminate a small window where the 647 // symlink can be exploited. 648 // 649 if (!is_directory_secure(usrdir_name)) { 650 FREE_C_HEAP_ARRAY(char, usrdir_name); 651 os::closedir(subdirp); 652 continue; 653 } 654 655 struct dirent* udentry; 656 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal); 657 errno = 0; 658 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) { 659 660 if (filename_to_pid(udentry->d_name) == vmid) { 661 struct stat statbuf; 662 int result; 663 664 char* filename = NEW_C_HEAP_ARRAY(char, 665 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal); 666 667 strcpy(filename, usrdir_name); 668 strcat(filename, "/"); 669 strcat(filename, udentry->d_name); 670 671 // don't follow symbolic links for the file 672 RESTARTABLE(::lstat(filename, &statbuf), result); 673 if (result == OS_ERR) { 674 FREE_C_HEAP_ARRAY(char, filename); 675 continue; 676 } 677 678 // skip over files that are not regular files. 679 if (!S_ISREG(statbuf.st_mode)) { 680 FREE_C_HEAP_ARRAY(char, filename); 681 continue; 682 } 683 684 // compare and save filename with latest creation time 685 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { 686 687 if (statbuf.st_ctime > oldest_ctime) { 688 char* user = strchr(dentry->d_name, '_') + 1; 689 690 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user); 691 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal); 692 693 strcpy(oldest_user, user); 694 oldest_ctime = statbuf.st_ctime; 695 } 696 } 697 698 FREE_C_HEAP_ARRAY(char, filename); 699 } 700 } 701 os::closedir(subdirp); 702 FREE_C_HEAP_ARRAY(char, udbuf); 703 FREE_C_HEAP_ARRAY(char, usrdir_name); 704 } 705 os::closedir(tmpdirp); 706 FREE_C_HEAP_ARRAY(char, tdbuf); 707 708 return(oldest_user); 709} 710 711// return the name of the user that owns the JVM indicated by the given vmid. 712// 713static char* get_user_name(int vmid, TRAPS) { 714 return get_user_name_slow(vmid, THREAD); 715} 716 717// return the file name of the backing store file for the named 718// shared memory region for the given user name and vmid. 719// 720// the caller is expected to free the allocated memory. 721// 722static char* get_sharedmem_filename(const char* dirname, int vmid) { 723 724 // add 2 for the file separator and a null terminator. 725 size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 726 727 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 728 snprintf(name, nbytes, "%s/%d", dirname, vmid); 729 730 return name; 731} 732 733 734// remove file 735// 736// this method removes the file specified by the given path 737// 738static void remove_file(const char* path) { 739 740 int result; 741 742 // if the file is a directory, the following unlink will fail. since 743 // we don't expect to find directories in the user temp directory, we 744 // won't try to handle this situation. even if accidentially or 745 // maliciously planted, the directory's presence won't hurt anything. 746 // 747 RESTARTABLE(::unlink(path), result); 748 if (PrintMiscellaneous && Verbose && result == OS_ERR) { 749 if (errno != ENOENT) { 750 warning("Could not unlink shared memory backing" 751 " store file %s : %s\n", path, os::strerror(errno)); 752 } 753 } 754} 755 756// Cleanup stale shared memory resources 757// 758// This method attempts to remove all stale shared memory files in 759// the named user temporary directory. It scans the named directory 760// for files matching the pattern ^$[0-9]*$. For each file found, the 761// process id is extracted from the file name and a test is run to 762// determine if the process is alive. If the process is not alive, 763// any stale file resources are removed. 764static void cleanup_sharedmem_resources(const char* dirname) { 765 766 int saved_cwd_fd; 767 // Open the directory. 768 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 769 if (dirp == NULL) { 770 // Directory doesn't exist or is insecure, so there is nothing to cleanup. 771 return; 772 } 773 774 // For each entry in the directory that matches the expected file 775 // name pattern, determine if the file resources are stale and if 776 // so, remove the file resources. Note, instrumented HotSpot processes 777 // for this user may start and/or terminate during this search and 778 // remove or create new files in this directory. The behavior of this 779 // loop under these conditions is dependent upon the implementation of 780 // opendir/readdir. 781 struct dirent* entry; 782 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal); 783 784 errno = 0; 785 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) { 786 787 pid_t pid = filename_to_pid(entry->d_name); 788 789 if (pid == 0) { 790 791 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 792 793 // Attempt to remove all unexpected files, except "." and "..". 794 unlink(entry->d_name); 795 } 796 797 errno = 0; 798 continue; 799 } 800 801 // We now have a file name that converts to a valid integer 802 // that could represent a process id . if this process id 803 // matches the current process id or the process is not running, 804 // then remove the stale file resources. 805 // 806 // Process liveness is detected by sending signal number 0 to 807 // the process id (see kill(2)). if kill determines that the 808 // process does not exist, then the file resources are removed. 809 // if kill determines that that we don't have permission to 810 // signal the process, then the file resources are assumed to 811 // be stale and are removed because the resources for such a 812 // process should be in a different user specific directory. 813 if ((pid == os::current_process_id()) || 814 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 815 816 unlink(entry->d_name); 817 } 818 errno = 0; 819 } 820 821 // Close the directory and reset the current working directory. 822 close_directory_secure_cwd(dirp, saved_cwd_fd); 823 824 FREE_C_HEAP_ARRAY(char, dbuf); 825} 826 827// Make the user specific temporary directory. Returns true if 828// the directory exists and is secure upon return. Returns false 829// if the directory exists but is either a symlink, is otherwise 830// insecure, or if an error occurred. 831static bool make_user_tmp_dir(const char* dirname) { 832 833 // Create the directory with 0755 permissions. note that the directory 834 // will be owned by euid::egid, which may not be the same as uid::gid. 835 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 836 if (errno == EEXIST) { 837 // The directory already exists and was probably created by another 838 // JVM instance. However, this could also be the result of a 839 // deliberate symlink. Verify that the existing directory is safe. 840 if (!is_directory_secure(dirname)) { 841 // Directory is not secure. 842 if (PrintMiscellaneous && Verbose) { 843 warning("%s directory is insecure\n", dirname); 844 } 845 return false; 846 } 847 } 848 else { 849 // we encountered some other failure while attempting 850 // to create the directory 851 // 852 if (PrintMiscellaneous && Verbose) { 853 warning("could not create directory %s: %s\n", 854 dirname, os::strerror(errno)); 855 } 856 return false; 857 } 858 } 859 return true; 860} 861 862// create the shared memory file resources 863// 864// This method creates the shared memory file with the given size 865// This method also creates the user specific temporary directory, if 866// it does not yet exist. 867// 868static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 869 870 // make the user temporary directory 871 if (!make_user_tmp_dir(dirname)) { 872 // could not make/find the directory or the found directory 873 // was not secure 874 return -1; 875 } 876 877 int saved_cwd_fd; 878 // Open the directory and set the current working directory to it. 879 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 880 if (dirp == NULL) { 881 // Directory doesn't exist or is insecure, so cannot create shared 882 // memory file. 883 return -1; 884 } 885 886 // Open the filename in the current directory. 887 // Cannot use O_TRUNC here; truncation of an existing file has to happen 888 // after the is_file_secure() check below. 889 int result; 890 891 // No O_NOFOLLOW defined at buildtime, and it is not documented for open; 892 // so provide a workaround in this case. 893#ifdef O_NOFOLLOW 894 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result); 895#else 896 // workaround function (jdk6 code) 897 result = open_o_nofollow(filename, O_RDWR|O_CREAT, S_IREAD|S_IWRITE); 898#endif 899 900 if (result == OS_ERR) { 901 if (PrintMiscellaneous && Verbose) { 902 if (errno == ELOOP) { 903 warning("file %s is a symlink and is not secure\n", filename); 904 } else { 905 warning("could not create file %s: %s\n", filename, os::strerror(errno)); 906 } 907 } 908 // Close the directory and reset the current working directory. 909 close_directory_secure_cwd(dirp, saved_cwd_fd); 910 911 return -1; 912 } 913 // Close the directory and reset the current working directory. 914 close_directory_secure_cwd(dirp, saved_cwd_fd); 915 916 // save the file descriptor 917 int fd = result; 918 919 // Check to see if the file is secure. 920 if (!is_file_secure(fd, filename)) { 921 ::close(fd); 922 return -1; 923 } 924 925 // Truncate the file to get rid of any existing data. 926 RESTARTABLE(::ftruncate(fd, (off_t)0), result); 927 if (result == OS_ERR) { 928 if (PrintMiscellaneous && Verbose) { 929 warning("could not truncate shared memory file: %s\n", os::strerror(errno)); 930 } 931 ::close(fd); 932 return -1; 933 } 934 // set the file size 935 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 936 if (result == OS_ERR) { 937 if (PrintMiscellaneous && Verbose) { 938 warning("could not set shared memory file size: %s\n", os::strerror(errno)); 939 } 940 ::close(fd); 941 return -1; 942 } 943 944 return fd; 945} 946 947// open the shared memory file for the given user and vmid. returns 948// the file descriptor for the open file or -1 if the file could not 949// be opened. 950// 951static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 952 953 // open the file 954 int result; 955 // provide a workaround in case no O_NOFOLLOW is defined at buildtime 956#ifdef O_NOFOLLOW 957 RESTARTABLE(::open(filename, oflags), result); 958#else 959 result = open_o_nofollow(filename, oflags); 960#endif 961 if (result == OS_ERR) { 962 if (errno == ENOENT) { 963 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 964 "Process not found", OS_ERR); 965 } 966 else if (errno == EACCES) { 967 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 968 "Permission denied", OS_ERR); 969 } 970 else { 971 THROW_MSG_(vmSymbols::java_io_IOException(), 972 os::strerror(errno), OS_ERR); 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, 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 1015 // get the short filename. 1016 char* short_filename = strrchr(filename, '/'); 1017 if (short_filename == NULL) { 1018 short_filename = filename; 1019 } else { 1020 short_filename++; 1021 } 1022 1023 // cleanup any stale shared memory files 1024 cleanup_sharedmem_resources(dirname); 1025 1026 assert(((size > 0) && (size % os::vm_page_size() == 0)), 1027 "unexpected PerfMemory region size"); 1028 1029 fd = create_sharedmem_resources(dirname, short_filename, size); 1030 1031 FREE_C_HEAP_ARRAY(char, user_name); 1032 FREE_C_HEAP_ARRAY(char, dirname); 1033 1034 if (fd == -1) { 1035 FREE_C_HEAP_ARRAY(char, filename); 1036 return NULL; 1037 } 1038 1039 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 1040 1041 result = ::close(fd); 1042 assert(result != OS_ERR, "could not close file"); 1043 1044 if (mapAddress == MAP_FAILED) { 1045 if (PrintMiscellaneous && Verbose) { 1046 warning("mmap failed - %s\n", os::strerror(errno)); 1047 } 1048 remove_file(filename); 1049 FREE_C_HEAP_ARRAY(char, filename); 1050 return NULL; 1051 } 1052 1053 // save the file name for use in delete_shared_memory() 1054 backing_store_file_name = filename; 1055 1056 // clear the shared memory region 1057 (void)::memset((void*) mapAddress, 0, size); 1058 1059 // It does not go through os api, the operation has to record from here. 1060 MemTracker::record_virtual_memory_reserve((address)mapAddress, size, CURRENT_PC, mtInternal); 1061 1062 return mapAddress; 1063} 1064 1065// release a named shared memory region 1066// 1067static void unmap_shared(char* addr, size_t bytes) { 1068 // Do not rely on os::reserve_memory/os::release_memory to use mmap. 1069 // Use os::reserve_memory/os::release_memory for PerfDisableSharedMem=1, mmap/munmap for PerfDisableSharedMem=0 1070 if (::munmap(addr, bytes) == -1) { 1071 warning("perfmemory: munmap failed (%d)\n", errno); 1072 } 1073} 1074 1075// create the PerfData memory region in shared memory. 1076// 1077static char* create_shared_memory(size_t size) { 1078 1079 // create the shared memory region. 1080 return mmap_create_shared(size); 1081} 1082 1083// delete the shared PerfData memory region 1084// 1085static void delete_shared_memory(char* addr, size_t size) { 1086 1087 // cleanup the persistent shared memory resources. since DestroyJavaVM does 1088 // not support unloading of the JVM, unmapping of the memory resource is 1089 // not performed. The memory will be reclaimed by the OS upon termination of 1090 // the process. The backing store file is deleted from the file system. 1091 1092 assert(!PerfDisableSharedMem, "shouldn't be here"); 1093 1094 if (backing_store_file_name != NULL) { 1095 remove_file(backing_store_file_name); 1096 // Don't.. Free heap memory could deadlock os::abort() if it is called 1097 // from signal handler. OS will reclaim the heap memory. 1098 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 1099 backing_store_file_name = NULL; 1100 } 1101} 1102 1103// return the size of the file for the given file descriptor 1104// or 0 if it is not a valid size for a shared memory file 1105// 1106static size_t sharedmem_filesize(int fd, TRAPS) { 1107 1108 struct stat statbuf; 1109 int result; 1110 1111 RESTARTABLE(::fstat(fd, &statbuf), result); 1112 if (result == OS_ERR) { 1113 if (PrintMiscellaneous && Verbose) { 1114 warning("fstat failed: %s\n", os::strerror(errno)); 1115 } 1116 THROW_MSG_0(vmSymbols::java_io_IOException(), 1117 "Could not determine PerfMemory size"); 1118 } 1119 1120 if ((statbuf.st_size == 0) || 1121 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 1122 THROW_MSG_0(vmSymbols::java_lang_Exception(), 1123 "Invalid PerfMemory size"); 1124 } 1125 1126 return (size_t)statbuf.st_size; 1127} 1128 1129// attach to a named shared memory region. 1130// 1131static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 1132 1133 char* mapAddress; 1134 int result; 1135 int fd; 1136 size_t size = 0; 1137 const char* luser = NULL; 1138 1139 int mmap_prot; 1140 int file_flags; 1141 1142 ResourceMark rm; 1143 1144 // map the high level access mode to the appropriate permission 1145 // constructs for the file and the shared memory mapping. 1146 if (mode == PerfMemory::PERF_MODE_RO) { 1147 mmap_prot = PROT_READ; 1148 // No O_NOFOLLOW defined at buildtime, and it is not documented for open. 1149#ifdef O_NOFOLLOW 1150 file_flags = O_RDONLY | O_NOFOLLOW; 1151#else 1152 file_flags = O_RDONLY; 1153#endif 1154 } 1155 else if (mode == PerfMemory::PERF_MODE_RW) { 1156#ifdef LATER 1157 mmap_prot = PROT_READ | PROT_WRITE; 1158 file_flags = O_RDWR | O_NOFOLLOW; 1159#else 1160 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1161 "Unsupported access mode"); 1162#endif 1163 } 1164 else { 1165 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1166 "Illegal access mode"); 1167 } 1168 1169 if (user == NULL || strlen(user) == 0) { 1170 luser = get_user_name(vmid, CHECK); 1171 } 1172 else { 1173 luser = user; 1174 } 1175 1176 if (luser == NULL) { 1177 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1178 "Could not map vmid to user Name"); 1179 } 1180 1181 char* dirname = get_user_tmp_dir(luser); 1182 1183 // since we don't follow symbolic links when creating the backing 1184 // store file, we don't follow them when attaching either. 1185 // 1186 if (!is_directory_secure(dirname)) { 1187 FREE_C_HEAP_ARRAY(char, dirname); 1188 if (luser != user) { 1189 FREE_C_HEAP_ARRAY(char, luser); 1190 } 1191 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1192 "Process not found"); 1193 } 1194 1195 char* filename = get_sharedmem_filename(dirname, vmid); 1196 1197 // copy heap memory to resource memory. the open_sharedmem_file 1198 // method below need to use the filename, but could throw an 1199 // exception. using a resource array prevents the leak that 1200 // would otherwise occur. 1201 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); 1202 strcpy(rfilename, filename); 1203 1204 // free the c heap resources that are no longer needed 1205 if (luser != user) FREE_C_HEAP_ARRAY(char, luser); 1206 FREE_C_HEAP_ARRAY(char, dirname); 1207 FREE_C_HEAP_ARRAY(char, filename); 1208 1209 // open the shared memory file for the give vmid 1210 fd = open_sharedmem_file(rfilename, file_flags, THREAD); 1211 1212 if (fd == OS_ERR) { 1213 return; 1214 } 1215 1216 if (HAS_PENDING_EXCEPTION) { 1217 ::close(fd); 1218 return; 1219 } 1220 1221 if (*sizep == 0) { 1222 size = sharedmem_filesize(fd, CHECK); 1223 } else { 1224 size = *sizep; 1225 } 1226 1227 assert(size > 0, "unexpected size <= 0"); 1228 1229 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 1230 1231 result = ::close(fd); 1232 assert(result != OS_ERR, "could not close file"); 1233 1234 if (mapAddress == MAP_FAILED) { 1235 if (PrintMiscellaneous && Verbose) { 1236 warning("mmap failed: %s\n", os::strerror(errno)); 1237 } 1238 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 1239 "Could not map PerfMemory"); 1240 } 1241 1242 // it does not go through os api, the operation has to record from here. 1243 MemTracker::record_virtual_memory_reserve((address)mapAddress, size, CURRENT_PC, mtInternal); 1244 1245 *addr = mapAddress; 1246 *sizep = size; 1247 1248 log_debug(perf, memops)("mapped " SIZE_FORMAT " bytes for vmid %d at " 1249 INTPTR_FORMAT "\n", size, vmid, p2i((void*)mapAddress)); 1250} 1251 1252// create the PerfData memory region 1253// 1254// This method creates the memory region used to store performance 1255// data for the JVM. The memory may be created in standard or 1256// shared memory. 1257// 1258void PerfMemory::create_memory_region(size_t size) { 1259 1260 if (PerfDisableSharedMem) { 1261 // do not share the memory for the performance data. 1262 _start = create_standard_memory(size); 1263 } 1264 else { 1265 _start = create_shared_memory(size); 1266 if (_start == NULL) { 1267 1268 // creation of the shared memory region failed, attempt 1269 // to create a contiguous, non-shared memory region instead. 1270 // 1271 if (PrintMiscellaneous && Verbose) { 1272 warning("Reverting to non-shared PerfMemory region.\n"); 1273 } 1274 PerfDisableSharedMem = true; 1275 _start = create_standard_memory(size); 1276 } 1277 } 1278 1279 if (_start != NULL) _capacity = size; 1280 1281} 1282 1283// delete the PerfData memory region 1284// 1285// This method deletes the memory region used to store performance 1286// data for the JVM. The memory region indicated by the <address, size> 1287// tuple will be inaccessible after a call to this method. 1288// 1289void PerfMemory::delete_memory_region() { 1290 1291 assert((start() != NULL && capacity() > 0), "verify proper state"); 1292 1293 // If user specifies PerfDataSaveFile, it will save the performance data 1294 // to the specified file name no matter whether PerfDataSaveToFile is specified 1295 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 1296 // -XX:+PerfDataSaveToFile. 1297 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 1298 save_memory_to_file(start(), capacity()); 1299 } 1300 1301 if (PerfDisableSharedMem) { 1302 delete_standard_memory(start(), capacity()); 1303 } 1304 else { 1305 delete_shared_memory(start(), capacity()); 1306 } 1307} 1308 1309// attach to the PerfData memory region for another JVM 1310// 1311// This method returns an <address, size> tuple that points to 1312// a memory buffer that is kept reasonably synchronized with 1313// the PerfData memory region for the indicated JVM. This 1314// buffer may be kept in synchronization via shared memory 1315// or some other mechanism that keeps the buffer updated. 1316// 1317// If the JVM chooses not to support the attachability feature, 1318// this method should throw an UnsupportedOperation exception. 1319// 1320// This implementation utilizes named shared memory to map 1321// the indicated process's PerfData memory region into this JVMs 1322// address space. 1323// 1324void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1325 1326 if (vmid == 0 || vmid == os::current_process_id()) { 1327 *addrp = start(); 1328 *sizep = capacity(); 1329 return; 1330 } 1331 1332 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1333} 1334 1335// detach from the PerfData memory region of another JVM 1336// 1337// This method detaches the PerfData memory region of another 1338// JVM, specified as an <address, size> tuple of a buffer 1339// in this process's address space. This method may perform 1340// arbitrary actions to accomplish the detachment. The memory 1341// region specified by <address, size> will be inaccessible after 1342// a call to this method. 1343// 1344// If the JVM chooses not to support the attachability feature, 1345// this method should throw an UnsupportedOperation exception. 1346// 1347// This implementation utilizes named shared memory to detach 1348// the indicated process's PerfData memory region from this 1349// process's address space. 1350// 1351void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1352 1353 assert(addr != 0, "address sanity check"); 1354 assert(bytes > 0, "capacity sanity check"); 1355 1356 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1357 // prevent accidental detachment of this process's PerfMemory region 1358 return; 1359 } 1360 1361 unmap_shared(addr, bytes); 1362} 1363