perfMemory_solaris.cpp revision 10627:1537c752a7f5
1/* 2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25#include "precompiled.hpp" 26#include "classfile/vmSymbols.hpp" 27#include "memory/allocation.inline.hpp" 28#include "memory/resourceArea.hpp" 29#include "oops/oop.inline.hpp" 30#include "os_solaris.inline.hpp" 31#include "runtime/handles.inline.hpp" 32#include "runtime/perfMemory.hpp" 33#include "services/memTracker.hpp" 34#include "utilities/exceptions.hpp" 35 36// put OS-includes here 37# include <sys/types.h> 38# include <sys/mman.h> 39# include <errno.h> 40# include <stdio.h> 41# include <unistd.h> 42# include <sys/stat.h> 43# include <signal.h> 44# include <pwd.h> 45# include <procfs.h> 46 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 { 108 109 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 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} 200 201 202// 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} 250 251 252// 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. 256// 257static bool is_dirfd_secure(int dir_fd) { 258 struct stat statbuf; 259 int result = 0; 260 261 RESTARTABLE(::fstat(dir_fd, &statbuf), result); 262 if (result == OS_ERR) { 263 return false; 264 } 265 266 // The path exists, now check its mode. 267 return is_statbuf_secure(&statbuf); 268} 269 270 271// Check to make sure fd1 and fd2 are referencing the same file system object. 272// 273static bool is_same_fsobject(int fd1, int fd2) { 274 struct stat statbuf1; 275 struct stat statbuf2; 276 int result = 0; 277 278 RESTARTABLE(::fstat(fd1, &statbuf1), result); 279 if (result == OS_ERR) { 280 return false; 281 } 282 RESTARTABLE(::fstat(fd2, &statbuf2), result); 283 if (result == OS_ERR) { 284 return false; 285 } 286 287 if ((statbuf1.st_ino == statbuf2.st_ino) && 288 (statbuf1.st_dev == statbuf2.st_dev)) { 289 return true; 290 } else { 291 return false; 292 } 293} 294 295 296// Open the directory of the given path and validate it. 297// Return a DIR * of the open directory. 298// 299static DIR *open_directory_secure(const char* dirname) { 300 // Open the directory using open() so that it can be verified 301 // to be secure by calling is_dirfd_secure(), opendir() and then check 302 // to see if they are the same file system object. This method does not 303 // introduce a window of opportunity for the directory to be attacked that 304 // calling opendir() and is_directory_secure() does. 305 int result; 306 DIR *dirp = NULL; 307 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result); 308 if (result == OS_ERR) { 309 // Directory doesn't exist or is a symlink, so there is nothing to cleanup. 310 if (PrintMiscellaneous && Verbose) { 311 if (errno == ELOOP) { 312 warning("directory %s is a symlink and is not secure\n", dirname); 313 } else { 314 warning("could not open directory %s: %s\n", dirname, os::strerror(errno)); 315 } 316 } 317 return dirp; 318 } 319 int fd = result; 320 321 // Determine if the open directory is secure. 322 if (!is_dirfd_secure(fd)) { 323 // The directory is not a secure directory. 324 os::close(fd); 325 return dirp; 326 } 327 328 // Open the directory. 329 dirp = ::opendir(dirname); 330 if (dirp == NULL) { 331 // The directory doesn't exist, close fd and return. 332 os::close(fd); 333 return dirp; 334 } 335 336 // Check to make sure fd and dirp are referencing the same file system object. 337 if (!is_same_fsobject(fd, dirp->dd_fd)) { 338 // The directory is not secure. 339 os::close(fd); 340 os::closedir(dirp); 341 dirp = NULL; 342 return dirp; 343 } 344 345 // Close initial open now that we know directory is secure 346 os::close(fd); 347 348 return dirp; 349} 350 351// NOTE: The code below uses fchdir(), open() and unlink() because 352// fdopendir(), openat() and unlinkat() are not supported on all 353// versions. Once the support for fdopendir(), openat() and unlinkat() 354// is available on all supported versions the code can be changed 355// to use these functions. 356 357// Open the directory of the given path, validate it and set the 358// current working directory to it. 359// Return a DIR * of the open directory and the saved cwd fd. 360// 361static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) { 362 363 // Open the directory. 364 DIR* dirp = open_directory_secure(dirname); 365 if (dirp == NULL) { 366 // Directory doesn't exist or is insecure, so there is nothing to cleanup. 367 return dirp; 368 } 369 int fd = dirp->dd_fd; 370 371 // Open a fd to the cwd and save it off. 372 int result; 373 RESTARTABLE(::open(".", O_RDONLY), result); 374 if (result == OS_ERR) { 375 *saved_cwd_fd = -1; 376 } else { 377 *saved_cwd_fd = result; 378 } 379 380 // Set the current directory to dirname by using the fd of the directory and 381 // handle errors, otherwise shared memory files will be created in cwd. 382 result = fchdir(fd); 383 if (result == OS_ERR) { 384 if (PrintMiscellaneous && Verbose) { 385 warning("could not change to directory %s", dirname); 386 } 387 if (*saved_cwd_fd != -1) { 388 ::close(*saved_cwd_fd); 389 *saved_cwd_fd = -1; 390 } 391 // Close the directory. 392 os::closedir(dirp); 393 return NULL; 394 } else { 395 return dirp; 396 } 397} 398 399// Close the directory and restore the current working directory. 400// 401static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) { 402 403 int result; 404 // If we have a saved cwd change back to it and close the fd. 405 if (saved_cwd_fd != -1) { 406 result = fchdir(saved_cwd_fd); 407 ::close(saved_cwd_fd); 408 } 409 410 // Close the directory. 411 os::closedir(dirp); 412} 413 414// Check if the given file descriptor is considered a secure. 415// 416static bool is_file_secure(int fd, const char *filename) { 417 418 int result; 419 struct stat statbuf; 420 421 // Determine if the file is secure. 422 RESTARTABLE(::fstat(fd, &statbuf), result); 423 if (result == OS_ERR) { 424 if (PrintMiscellaneous && Verbose) { 425 warning("fstat failed on %s: %s\n", filename, os::strerror(errno)); 426 } 427 return false; 428 } 429 if (statbuf.st_nlink > 1) { 430 // A file with multiple links is not expected. 431 if (PrintMiscellaneous && Verbose) { 432 warning("file %s has multiple links\n", filename); 433 } 434 return false; 435 } 436 return true; 437} 438 439// return the user name for the given user id 440// 441// the caller is expected to free the allocated memory. 442// 443static char* get_user_name(uid_t uid) { 444 445 struct passwd pwent; 446 447 // determine the max pwbuf size from sysconf, and hardcode 448 // a default if this not available through sysconf. 449 // 450 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); 451 if (bufsize == -1) 452 bufsize = 1024; 453 454 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 455 456#ifdef _GNU_SOURCE 457 struct passwd* p = NULL; 458 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 459#else // _GNU_SOURCE 460 struct passwd* p = getpwuid_r(uid, &pwent, pwbuf, (int)bufsize); 461#endif // _GNU_SOURCE 462 463 if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 464 if (PrintMiscellaneous && Verbose) { 465 if (p == NULL) { 466 warning("Could not retrieve passwd entry: %s\n", 467 os::strerror(errno)); 468 } 469 else { 470 warning("Could not determine user name: %s\n", 471 p->pw_name == NULL ? "pw_name = NULL" : 472 "pw_name zero length"); 473 } 474 } 475 FREE_C_HEAP_ARRAY(char, pwbuf); 476 return NULL; 477 } 478 479 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal); 480 strcpy(user_name, p->pw_name); 481 482 FREE_C_HEAP_ARRAY(char, pwbuf); 483 return user_name; 484} 485 486// return the name of the user that owns the process identified by vmid. 487// 488// This method uses a slow directory search algorithm to find the backing 489// store file for the specified vmid and returns the user name, as determined 490// by the user name suffix of the hsperfdata_<username> directory name. 491// 492// the caller is expected to free the allocated memory. 493// 494static char* get_user_name_slow(int vmid, TRAPS) { 495 496 // short circuit the directory search if the process doesn't even exist. 497 if (kill(vmid, 0) == OS_ERR) { 498 if (errno == ESRCH) { 499 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 500 "Process not found"); 501 } 502 else /* EPERM */ { 503 THROW_MSG_0(vmSymbols::java_io_IOException(), os::strerror(errno)); 504 } 505 } 506 507 // directory search 508 char* oldest_user = NULL; 509 time_t oldest_ctime = 0; 510 511 const char* tmpdirname = os::get_temp_directory(); 512 513 // open the temp directory 514 DIR* tmpdirp = os::opendir(tmpdirname); 515 516 if (tmpdirp == NULL) { 517 // Cannot open the directory to get the user name, return. 518 return NULL; 519 } 520 521 // for each entry in the directory that matches the pattern hsperfdata_*, 522 // open the directory and check if the file for the given vmid exists. 523 // The file with the expected name and the latest creation date is used 524 // to determine the user name for the process id. 525 // 526 struct dirent* dentry; 527 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal); 528 errno = 0; 529 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) { 530 531 // check if the directory entry is a hsperfdata file 532 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { 533 continue; 534 } 535 536 char* usrdir_name = NEW_C_HEAP_ARRAY(char, 537 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal); 538 strcpy(usrdir_name, tmpdirname); 539 strcat(usrdir_name, "/"); 540 strcat(usrdir_name, dentry->d_name); 541 542 // open the user directory 543 DIR* subdirp = open_directory_secure(usrdir_name); 544 545 if (subdirp == NULL) { 546 FREE_C_HEAP_ARRAY(char, usrdir_name); 547 continue; 548 } 549 550 // Since we don't create the backing store files in directories 551 // pointed to by symbolic links, we also don't follow them when 552 // looking for the files. We check for a symbolic link after the 553 // call to opendir in order to eliminate a small window where the 554 // symlink can be exploited. 555 // 556 if (!is_directory_secure(usrdir_name)) { 557 FREE_C_HEAP_ARRAY(char, usrdir_name); 558 os::closedir(subdirp); 559 continue; 560 } 561 562 struct dirent* udentry; 563 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal); 564 errno = 0; 565 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) { 566 567 if (filename_to_pid(udentry->d_name) == vmid) { 568 struct stat statbuf; 569 int result; 570 571 char* filename = NEW_C_HEAP_ARRAY(char, 572 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal); 573 574 strcpy(filename, usrdir_name); 575 strcat(filename, "/"); 576 strcat(filename, udentry->d_name); 577 578 // don't follow symbolic links for the file 579 RESTARTABLE(::lstat(filename, &statbuf), result); 580 if (result == OS_ERR) { 581 FREE_C_HEAP_ARRAY(char, filename); 582 continue; 583 } 584 585 // skip over files that are not regular files. 586 if (!S_ISREG(statbuf.st_mode)) { 587 FREE_C_HEAP_ARRAY(char, filename); 588 continue; 589 } 590 591 // compare and save filename with latest creation time 592 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { 593 594 if (statbuf.st_ctime > oldest_ctime) { 595 char* user = strchr(dentry->d_name, '_') + 1; 596 597 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user); 598 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal); 599 600 strcpy(oldest_user, user); 601 oldest_ctime = statbuf.st_ctime; 602 } 603 } 604 605 FREE_C_HEAP_ARRAY(char, filename); 606 } 607 } 608 os::closedir(subdirp); 609 FREE_C_HEAP_ARRAY(char, udbuf); 610 FREE_C_HEAP_ARRAY(char, usrdir_name); 611 } 612 os::closedir(tmpdirp); 613 FREE_C_HEAP_ARRAY(char, tdbuf); 614 615 return(oldest_user); 616} 617 618// return the name of the user that owns the JVM indicated by the given vmid. 619// 620static char* get_user_name(int vmid, TRAPS) { 621 622 char psinfo_name[PATH_MAX]; 623 int result; 624 625 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid); 626 627 RESTARTABLE(::open(psinfo_name, O_RDONLY), result); 628 629 if (result != OS_ERR) { 630 int fd = result; 631 632 psinfo_t psinfo; 633 char* addr = (char*)&psinfo; 634 635 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) { 636 637 RESTARTABLE(::read(fd, addr, remaining), result); 638 if (result == OS_ERR) { 639 ::close(fd); 640 THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error"); 641 } else { 642 remaining-=result; 643 addr+=result; 644 } 645 } 646 647 ::close(fd); 648 649 // get the user name for the effective user id of the process 650 char* user_name = get_user_name(psinfo.pr_euid); 651 652 return user_name; 653 } 654 655 if (result == OS_ERR && errno == EACCES) { 656 657 // In this case, the psinfo file for the process id existed, 658 // but we didn't have permission to access it. 659 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 660 os::strerror(errno)); 661 } 662 663 // at this point, we don't know if the process id itself doesn't 664 // exist or if the psinfo file doesn't exit. If the psinfo file 665 // doesn't exist, then we are running on Solaris 2.5.1 or earlier. 666 // since the structured procfs and old procfs interfaces can't be 667 // mixed, we attempt to find the file through a directory search. 668 669 return get_user_name_slow(vmid, THREAD); 670} 671 672// return the file name of the backing store file for the named 673// shared memory region for the given user name and vmid. 674// 675// the caller is expected to free the allocated memory. 676// 677static char* get_sharedmem_filename(const char* dirname, int vmid) { 678 679 // add 2 for the file separator and a NULL terminator. 680 size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 681 682 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 683 snprintf(name, nbytes, "%s/%d", dirname, vmid); 684 685 return name; 686} 687 688 689// remove file 690// 691// this method removes the file specified by the given path 692// 693static void remove_file(const char* path) { 694 695 int result; 696 697 // if the file is a directory, the following unlink will fail. since 698 // we don't expect to find directories in the user temp directory, we 699 // won't try to handle this situation. even if accidentially or 700 // maliciously planted, the directory's presence won't hurt anything. 701 // 702 RESTARTABLE(::unlink(path), result); 703 if (PrintMiscellaneous && Verbose && result == OS_ERR) { 704 if (errno != ENOENT) { 705 warning("Could not unlink shared memory backing" 706 " store file %s : %s\n", path, os::strerror(errno)); 707 } 708 } 709} 710 711 712// cleanup stale shared memory resources 713// 714// This method attempts to remove all stale shared memory files in 715// the named user temporary directory. It scans the named directory 716// for files matching the pattern ^$[0-9]*$. For each file found, the 717// process id is extracted from the file name and a test is run to 718// determine if the process is alive. If the process is not alive, 719// any stale file resources are removed. 720// 721static void cleanup_sharedmem_resources(const char* dirname) { 722 723 int saved_cwd_fd; 724 // open the directory 725 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 726 if (dirp == NULL) { 727 // directory doesn't exist or is insecure, so there is nothing to cleanup 728 return; 729 } 730 731 // for each entry in the directory that matches the expected file 732 // name pattern, determine if the file resources are stale and if 733 // so, remove the file resources. Note, instrumented HotSpot processes 734 // for this user may start and/or terminate during this search and 735 // remove or create new files in this directory. The behavior of this 736 // loop under these conditions is dependent upon the implementation of 737 // opendir/readdir. 738 // 739 struct dirent* entry; 740 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal); 741 742 errno = 0; 743 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) { 744 745 pid_t pid = filename_to_pid(entry->d_name); 746 747 if (pid == 0) { 748 749 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 750 751 // attempt to remove all unexpected files, except "." and ".." 752 unlink(entry->d_name); 753 } 754 755 errno = 0; 756 continue; 757 } 758 759 // we now have a file name that converts to a valid integer 760 // that could represent a process id . if this process id 761 // matches the current process id or the process is not running, 762 // then remove the stale file resources. 763 // 764 // process liveness is detected by sending signal number 0 to 765 // the process id (see kill(2)). if kill determines that the 766 // process does not exist, then the file resources are removed. 767 // if kill determines that that we don't have permission to 768 // signal the process, then the file resources are assumed to 769 // be stale and are removed because the resources for such a 770 // process should be in a different user specific directory. 771 // 772 if ((pid == os::current_process_id()) || 773 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 774 775 unlink(entry->d_name); 776 } 777 errno = 0; 778 } 779 780 // close the directory and reset the current working directory 781 close_directory_secure_cwd(dirp, saved_cwd_fd); 782 783 FREE_C_HEAP_ARRAY(char, dbuf); 784} 785 786// make the user specific temporary directory. Returns true if 787// the directory exists and is secure upon return. Returns false 788// if the directory exists but is either a symlink, is otherwise 789// insecure, or if an error occurred. 790// 791static bool make_user_tmp_dir(const char* dirname) { 792 793 // create the directory with 0755 permissions. note that the directory 794 // will be owned by euid::egid, which may not be the same as uid::gid. 795 // 796 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 797 if (errno == EEXIST) { 798 // The directory already exists and was probably created by another 799 // JVM instance. However, this could also be the result of a 800 // deliberate symlink. Verify that the existing directory is safe. 801 // 802 if (!is_directory_secure(dirname)) { 803 // directory is not secure 804 if (PrintMiscellaneous && Verbose) { 805 warning("%s directory is insecure\n", dirname); 806 } 807 return false; 808 } 809 } 810 else { 811 // we encountered some other failure while attempting 812 // to create the directory 813 // 814 if (PrintMiscellaneous && Verbose) { 815 warning("could not create directory %s: %s\n", 816 dirname, os::strerror(errno)); 817 } 818 return false; 819 } 820 } 821 return true; 822} 823 824// create the shared memory file resources 825// 826// This method creates the shared memory file with the given size 827// This method also creates the user specific temporary directory, if 828// it does not yet exist. 829// 830static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 831 832 // make the user temporary directory 833 if (!make_user_tmp_dir(dirname)) { 834 // could not make/find the directory or the found directory 835 // was not secure 836 return -1; 837 } 838 839 int saved_cwd_fd; 840 // open the directory and set the current working directory to it 841 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 842 if (dirp == NULL) { 843 // Directory doesn't exist or is insecure, so cannot create shared 844 // memory file. 845 return -1; 846 } 847 848 // Open the filename in the current directory. 849 // Cannot use O_TRUNC here; truncation of an existing file has to happen 850 // after the is_file_secure() check below. 851 int result; 852 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result); 853 if (result == OS_ERR) { 854 if (PrintMiscellaneous && Verbose) { 855 if (errno == ELOOP) { 856 warning("file %s is a symlink and is not secure\n", filename); 857 } else { 858 warning("could not create file %s: %s\n", filename, os::strerror(errno)); 859 } 860 } 861 // close the directory and reset the current working directory 862 close_directory_secure_cwd(dirp, saved_cwd_fd); 863 864 return -1; 865 } 866 // close the directory and reset the current working directory 867 close_directory_secure_cwd(dirp, saved_cwd_fd); 868 869 // save the file descriptor 870 int fd = result; 871 872 // check to see if the file is secure 873 if (!is_file_secure(fd, filename)) { 874 ::close(fd); 875 return -1; 876 } 877 878 // truncate the file to get rid of any existing data 879 RESTARTABLE(::ftruncate(fd, (off_t)0), result); 880 if (result == OS_ERR) { 881 if (PrintMiscellaneous && Verbose) { 882 warning("could not truncate shared memory file: %s\n", os::strerror(errno)); 883 } 884 ::close(fd); 885 return -1; 886 } 887 // set the file size 888 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 889 if (result == OS_ERR) { 890 if (PrintMiscellaneous && Verbose) { 891 warning("could not set shared memory file size: %s\n", os::strerror(errno)); 892 } 893 ::close(fd); 894 return -1; 895 } 896 897 return fd; 898} 899 900// open the shared memory file for the given user and vmid. returns 901// the file descriptor for the open file or -1 if the file could not 902// be opened. 903// 904static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 905 906 // open the file 907 int result; 908 RESTARTABLE(::open(filename, oflags), result); 909 if (result == OS_ERR) { 910 if (errno == ENOENT) { 911 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 912 "Process not found", OS_ERR); 913 } 914 else if (errno == EACCES) { 915 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 916 "Permission denied", OS_ERR); 917 } 918 else { 919 THROW_MSG_(vmSymbols::java_io_IOException(), os::strerror(errno), OS_ERR); 920 } 921 } 922 int fd = result; 923 924 // check to see if the file is secure 925 if (!is_file_secure(fd, filename)) { 926 ::close(fd); 927 return -1; 928 } 929 930 return fd; 931} 932 933// create a named shared memory region. returns the address of the 934// memory region on success or NULL on failure. A return value of 935// NULL will ultimately disable the shared memory feature. 936// 937// On Solaris and Linux, the name space for shared memory objects 938// is the file system name space. 939// 940// A monitoring application attaching to a JVM does not need to know 941// the file system name of the shared memory object. However, it may 942// be convenient for applications to discover the existence of newly 943// created and terminating JVMs by watching the file system name space 944// for files being created or removed. 945// 946static char* mmap_create_shared(size_t size) { 947 948 int result; 949 int fd; 950 char* mapAddress; 951 952 int vmid = os::current_process_id(); 953 954 char* user_name = get_user_name(geteuid()); 955 956 if (user_name == NULL) 957 return NULL; 958 959 char* dirname = get_user_tmp_dir(user_name); 960 char* filename = get_sharedmem_filename(dirname, vmid); 961 962 // get the short filename 963 char* short_filename = strrchr(filename, '/'); 964 if (short_filename == NULL) { 965 short_filename = filename; 966 } else { 967 short_filename++; 968 } 969 970 // cleanup any stale shared memory files 971 cleanup_sharedmem_resources(dirname); 972 973 assert(((size > 0) && (size % os::vm_page_size() == 0)), 974 "unexpected PerfMemory region size"); 975 976 fd = create_sharedmem_resources(dirname, short_filename, size); 977 978 FREE_C_HEAP_ARRAY(char, user_name); 979 FREE_C_HEAP_ARRAY(char, dirname); 980 981 if (fd == -1) { 982 FREE_C_HEAP_ARRAY(char, filename); 983 return NULL; 984 } 985 986 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 987 988 result = ::close(fd); 989 assert(result != OS_ERR, "could not close file"); 990 991 if (mapAddress == MAP_FAILED) { 992 if (PrintMiscellaneous && Verbose) { 993 warning("mmap failed - %s\n", os::strerror(errno)); 994 } 995 remove_file(filename); 996 FREE_C_HEAP_ARRAY(char, filename); 997 return NULL; 998 } 999 1000 // save the file name for use in delete_shared_memory() 1001 backing_store_file_name = filename; 1002 1003 // clear the shared memory region 1004 (void)::memset((void*) mapAddress, 0, size); 1005 1006 // it does not go through os api, the operation has to record from here 1007 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, 1008 size, CURRENT_PC, mtInternal); 1009 1010 return mapAddress; 1011} 1012 1013// release a named shared memory region 1014// 1015static void unmap_shared(char* addr, size_t bytes) { 1016 os::release_memory(addr, bytes); 1017} 1018 1019// create the PerfData memory region in shared memory. 1020// 1021static char* create_shared_memory(size_t size) { 1022 1023 // create the shared memory region. 1024 return mmap_create_shared(size); 1025} 1026 1027// delete the shared PerfData memory region 1028// 1029static void delete_shared_memory(char* addr, size_t size) { 1030 1031 // cleanup the persistent shared memory resources. since DestroyJavaVM does 1032 // not support unloading of the JVM, unmapping of the memory resource is 1033 // not performed. The memory will be reclaimed by the OS upon termination of 1034 // the process. The backing store file is deleted from the file system. 1035 1036 assert(!PerfDisableSharedMem, "shouldn't be here"); 1037 1038 if (backing_store_file_name != NULL) { 1039 remove_file(backing_store_file_name); 1040 // Don't.. Free heap memory could deadlock os::abort() if it is called 1041 // from signal handler. OS will reclaim the heap memory. 1042 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 1043 backing_store_file_name = NULL; 1044 } 1045} 1046 1047// return the size of the file for the given file descriptor 1048// or 0 if it is not a valid size for a shared memory file 1049// 1050static size_t sharedmem_filesize(int fd, TRAPS) { 1051 1052 struct stat statbuf; 1053 int result; 1054 1055 RESTARTABLE(::fstat(fd, &statbuf), result); 1056 if (result == OS_ERR) { 1057 if (PrintMiscellaneous && Verbose) { 1058 warning("fstat failed: %s\n", os::strerror(errno)); 1059 } 1060 THROW_MSG_0(vmSymbols::java_io_IOException(), 1061 "Could not determine PerfMemory size"); 1062 } 1063 1064 if ((statbuf.st_size == 0) || 1065 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 1066 THROW_MSG_0(vmSymbols::java_lang_Exception(), 1067 "Invalid PerfMemory size"); 1068 } 1069 1070 return (size_t)statbuf.st_size; 1071} 1072 1073// attach to a named shared memory region. 1074// 1075static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 1076 1077 char* mapAddress; 1078 int result; 1079 int fd; 1080 size_t size = 0; 1081 const char* luser = NULL; 1082 1083 int mmap_prot; 1084 int file_flags; 1085 1086 ResourceMark rm; 1087 1088 // map the high level access mode to the appropriate permission 1089 // constructs for the file and the shared memory mapping. 1090 if (mode == PerfMemory::PERF_MODE_RO) { 1091 mmap_prot = PROT_READ; 1092 file_flags = O_RDONLY | O_NOFOLLOW; 1093 } 1094 else if (mode == PerfMemory::PERF_MODE_RW) { 1095#ifdef LATER 1096 mmap_prot = PROT_READ | PROT_WRITE; 1097 file_flags = O_RDWR | O_NOFOLLOW; 1098#else 1099 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1100 "Unsupported access mode"); 1101#endif 1102 } 1103 else { 1104 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1105 "Illegal access mode"); 1106 } 1107 1108 if (user == NULL || strlen(user) == 0) { 1109 luser = get_user_name(vmid, CHECK); 1110 } 1111 else { 1112 luser = user; 1113 } 1114 1115 if (luser == NULL) { 1116 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1117 "Could not map vmid to user Name"); 1118 } 1119 1120 char* dirname = get_user_tmp_dir(luser); 1121 1122 // since we don't follow symbolic links when creating the backing 1123 // store file, we don't follow them when attaching either. 1124 // 1125 if (!is_directory_secure(dirname)) { 1126 FREE_C_HEAP_ARRAY(char, dirname); 1127 if (luser != user) { 1128 FREE_C_HEAP_ARRAY(char, luser); 1129 } 1130 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1131 "Process not found"); 1132 } 1133 1134 char* filename = get_sharedmem_filename(dirname, vmid); 1135 1136 // copy heap memory to resource memory. the open_sharedmem_file 1137 // method below need to use the filename, but could throw an 1138 // exception. using a resource array prevents the leak that 1139 // would otherwise occur. 1140 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); 1141 strcpy(rfilename, filename); 1142 1143 // free the c heap resources that are no longer needed 1144 if (luser != user) FREE_C_HEAP_ARRAY(char, luser); 1145 FREE_C_HEAP_ARRAY(char, dirname); 1146 FREE_C_HEAP_ARRAY(char, filename); 1147 1148 // open the shared memory file for the give vmid 1149 fd = open_sharedmem_file(rfilename, file_flags, THREAD); 1150 1151 if (fd == OS_ERR) { 1152 return; 1153 } 1154 1155 if (HAS_PENDING_EXCEPTION) { 1156 ::close(fd); 1157 return; 1158 } 1159 1160 if (*sizep == 0) { 1161 size = sharedmem_filesize(fd, CHECK); 1162 } else { 1163 size = *sizep; 1164 } 1165 1166 assert(size > 0, "unexpected size <= 0"); 1167 1168 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 1169 1170 result = ::close(fd); 1171 assert(result != OS_ERR, "could not close file"); 1172 1173 if (mapAddress == MAP_FAILED) { 1174 if (PrintMiscellaneous && Verbose) { 1175 warning("mmap failed: %s\n", os::strerror(errno)); 1176 } 1177 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 1178 "Could not map PerfMemory"); 1179 } 1180 1181 // it does not go through os api, the operation has to record from here 1182 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, 1183 size, CURRENT_PC, mtInternal); 1184 1185 *addr = mapAddress; 1186 *sizep = size; 1187 1188 if (PerfTraceMemOps) { 1189 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at " 1190 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress); 1191 } 1192} 1193 1194 1195 1196 1197// create the PerfData memory region 1198// 1199// This method creates the memory region used to store performance 1200// data for the JVM. The memory may be created in standard or 1201// shared memory. 1202// 1203void PerfMemory::create_memory_region(size_t size) { 1204 1205 if (PerfDisableSharedMem) { 1206 // do not share the memory for the performance data. 1207 _start = create_standard_memory(size); 1208 } 1209 else { 1210 _start = create_shared_memory(size); 1211 if (_start == NULL) { 1212 1213 // creation of the shared memory region failed, attempt 1214 // to create a contiguous, non-shared memory region instead. 1215 // 1216 if (PrintMiscellaneous && Verbose) { 1217 warning("Reverting to non-shared PerfMemory region.\n"); 1218 } 1219 PerfDisableSharedMem = true; 1220 _start = create_standard_memory(size); 1221 } 1222 } 1223 1224 if (_start != NULL) _capacity = size; 1225 1226} 1227 1228// delete the PerfData memory region 1229// 1230// This method deletes the memory region used to store performance 1231// data for the JVM. The memory region indicated by the <address, size> 1232// tuple will be inaccessible after a call to this method. 1233// 1234void PerfMemory::delete_memory_region() { 1235 1236 assert((start() != NULL && capacity() > 0), "verify proper state"); 1237 1238 // If user specifies PerfDataSaveFile, it will save the performance data 1239 // to the specified file name no matter whether PerfDataSaveToFile is specified 1240 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 1241 // -XX:+PerfDataSaveToFile. 1242 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 1243 save_memory_to_file(start(), capacity()); 1244 } 1245 1246 if (PerfDisableSharedMem) { 1247 delete_standard_memory(start(), capacity()); 1248 } 1249 else { 1250 delete_shared_memory(start(), capacity()); 1251 } 1252} 1253 1254// attach to the PerfData memory region for another JVM 1255// 1256// This method returns an <address, size> tuple that points to 1257// a memory buffer that is kept reasonably synchronized with 1258// the PerfData memory region for the indicated JVM. This 1259// buffer may be kept in synchronization via shared memory 1260// or some other mechanism that keeps the buffer updated. 1261// 1262// If the JVM chooses not to support the attachability feature, 1263// this method should throw an UnsupportedOperation exception. 1264// 1265// This implementation utilizes named shared memory to map 1266// the indicated process's PerfData memory region into this JVMs 1267// address space. 1268// 1269void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1270 1271 if (vmid == 0 || vmid == os::current_process_id()) { 1272 *addrp = start(); 1273 *sizep = capacity(); 1274 return; 1275 } 1276 1277 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1278} 1279 1280// detach from the PerfData memory region of another JVM 1281// 1282// This method detaches the PerfData memory region of another 1283// JVM, specified as an <address, size> tuple of a buffer 1284// in this process's address space. This method may perform 1285// arbitrary actions to accomplish the detachment. The memory 1286// region specified by <address, size> will be inaccessible after 1287// a call to this method. 1288// 1289// If the JVM chooses not to support the attachability feature, 1290// this method should throw an UnsupportedOperation exception. 1291// 1292// This implementation utilizes named shared memory to detach 1293// the indicated process's PerfData memory region from this 1294// process's address space. 1295// 1296void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1297 1298 assert(addr != 0, "address sanity check"); 1299 assert(bytes > 0, "capacity sanity check"); 1300 1301 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1302 // prevent accidental detachment of this process's PerfMemory region 1303 return; 1304 } 1305 1306 unmap_shared(addr, bytes); 1307} 1308