1 /* 2 * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/vmSymbols.hpp" 27 #include "memory/allocation.inline.hpp" 28 #include "memory/resourceArea.hpp" 29 #include "oops/oop.inline.hpp" 30 #include "os_bsd.inline.hpp" 31 #include "runtime/handles.inline.hpp" 32 #include "runtime/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 46 static char* backing_store_file_name = NULL; // name of the backing store 47 // file, if successfully created. 48 49 // Standard Memory Implementation Details 50 51 // create the PerfData memory region in standard memory. 52 // 53 static char* create_standard_memory(size_t size) { 54 55 // allocate an aligned chuck of memory 56 char* mapAddress = os::reserve_memory(size); 57 58 if (mapAddress == NULL) { 59 return NULL; 60 } 61 62 // commit memory 63 if (!os::commit_memory(mapAddress, size, !ExecMem)) { 64 if (PrintMiscellaneous && Verbose) { 65 warning("Could not commit PerfData memory\n"); 66 } 67 os::release_memory(mapAddress, size); 68 return NULL; 69 } 70 71 return mapAddress; 72 } 73 74 // delete the PerfData memory region 75 // 76 static void delete_standard_memory(char* addr, size_t size) { 77 78 // there are no persistent external resources to cleanup for standard 79 // memory. since DestroyJavaVM does not support unloading of the JVM, 80 // cleanup of the memory resource is not performed. The memory will be 81 // reclaimed by the OS upon termination of the process. 82 // 83 return; 84 } 85 86 // save the specified memory region to the given file 87 // 88 // Note: this function might be called from signal handler (by os::abort()), 89 // don't allocate heap memory. 90 // 91 static void save_memory_to_file(char* addr, size_t size) { 92 93 const char* destfile = PerfMemory::get_perfdata_file_path(); 94 assert(destfile[0] != '\0', "invalid PerfData file path"); 95 96 int result; 97 98 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), 99 result);; 100 if (result == OS_ERR) { 101 if (PrintMiscellaneous && Verbose) { 102 warning("Could not create Perfdata save file: %s: %s\n", 103 destfile, strerror(errno)); 104 } 105 } else { 106 int fd = result; 107 108 for (size_t remaining = size; remaining > 0;) { 109 110 RESTARTABLE(::write(fd, addr, remaining), result); 111 if (result == OS_ERR) { 112 if (PrintMiscellaneous && Verbose) { 113 warning("Could not write Perfdata save file: %s: %s\n", 114 destfile, strerror(errno)); 115 } 116 break; 117 } 118 119 remaining -= (size_t)result; 120 addr += result; 121 } 122 123 result = ::close(fd); 124 if (PrintMiscellaneous && Verbose) { 125 if (result == OS_ERR) { 126 warning("Could not close %s: %s\n", destfile, strerror(errno)); 127 } 128 } 129 } 130 FREE_C_HEAP_ARRAY(char, destfile, mtInternal); 131 } 132 133 134 // Shared Memory Implementation Details 135 136 // Note: the solaris and bsd shared memory implementation uses the mmap 137 // interface with a backing store file to implement named shared memory. 138 // Using the file system as the name space for shared memory allows a 139 // common name space to be supported across a variety of platforms. It 140 // also provides a name space that Java applications can deal with through 141 // simple file apis. 142 // 143 // The solaris and bsd implementations store the backing store file in 144 // a user specific temporary directory located in the /tmp file system, 145 // which is always a local file system and is sometimes a RAM based file 146 // system. 147 148 // return the user specific temporary directory name. 149 // 150 // the caller is expected to free the allocated memory. 151 // 152 static char* get_user_tmp_dir(const char* user) { 153 154 const char* tmpdir = os::get_temp_directory(); 155 const char* perfdir = PERFDATA_NAME; 156 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3; 157 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 158 159 // construct the path name to user specific tmp directory 160 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user); 161 162 return dirname; 163 } 164 165 // convert the given file name into a process id. if the file 166 // does not meet the file naming constraints, return 0. 167 // 168 static pid_t filename_to_pid(const char* filename) { 169 170 // a filename that doesn't begin with a digit is not a 171 // candidate for conversion. 172 // 173 if (!isdigit(*filename)) { 174 return 0; 175 } 176 177 // check if file name can be converted to an integer without 178 // any leftover characters. 179 // 180 char* remainder = NULL; 181 errno = 0; 182 pid_t pid = (pid_t)strtol(filename, &remainder, 10); 183 184 if (errno != 0) { 185 return 0; 186 } 187 188 // check for left over characters. If any, then the filename is 189 // not a candidate for conversion. 190 // 191 if (remainder != NULL && *remainder != '\0') { 192 return 0; 193 } 194 195 // successful conversion, return the pid 196 return pid; 197 } 198 199 200 // Check if the given statbuf is considered a secure directory for 201 // the backing store files. Returns true if the directory is considered 202 // a secure location. Returns false if the statbuf is a symbolic link or 203 // if an error occurred. 204 // 205 static bool is_statbuf_secure(struct stat *statp) { 206 if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) { 207 // The path represents a link or some non-directory file type, 208 // which is not what we expected. Declare it insecure. 209 // 210 return false; 211 } 212 // We have an existing directory, check if the permissions are safe. 213 // 214 if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) { 215 // The directory is open for writing and could be subjected 216 // to a symlink or a hard link attack. Declare it insecure. 217 // 218 return false; 219 } 220 // If user is not root then see if the uid of the directory matches the effective uid of the process. 221 uid_t euid = geteuid(); 222 if ((euid != 0) && (statp->st_uid != euid)) { 223 // The directory was not created by this user, declare it insecure. 224 // 225 return false; 226 } 227 return true; 228 } 229 230 231 // Check if the given path is considered a secure directory for 232 // the backing store files. Returns true if the directory exists 233 // and is considered a secure location. Returns false if the path 234 // is a symbolic link or if an error occurred. 235 // 236 static bool is_directory_secure(const char* path) { 237 struct stat statbuf; 238 int result = 0; 239 240 RESTARTABLE(::lstat(path, &statbuf), result); 241 if (result == OS_ERR) { 242 return false; 243 } 244 245 // The path exists, see if it is secure. 246 return is_statbuf_secure(&statbuf); 247 } 248 249 250 // Check if the given directory file descriptor is considered a secure 251 // directory for the backing store files. Returns true if the directory 252 // exists and is considered a secure location. Returns false if the path 253 // is a symbolic link or if an error occurred. 254 // 255 static 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. 270 // 271 static 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 } 292 293 294 // Open the directory of the given path and validate it. 295 // Return a DIR * of the open directory. 296 // 297 static DIR *open_directory_secure(const char* dirname) { 298 // Open the directory using open() so that it can be verified 299 // to be secure by calling is_dirfd_secure(), opendir() and then check 300 // to see if they are the same file system object. This method does not 301 // introduce a window of opportunity for the directory to be attacked that 302 // calling opendir() and is_directory_secure() does. 303 int result; 304 DIR *dirp = NULL; 305 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result); 306 if (result == OS_ERR) { 307 // Directory doesn't exist or is a symlink, so there is nothing to cleanup. 308 if (PrintMiscellaneous && Verbose) { 309 if (errno == ELOOP) { 310 warning("directory %s is a symlink and is not secure\n", dirname); 311 } else { 312 warning("could not open directory %s: %s\n", dirname, strerror(errno)); 313 } 314 } 315 return dirp; 316 } 317 int fd = result; 318 319 // Determine if the open directory is secure. 320 if (!is_dirfd_secure(fd)) { 321 // The directory is not a secure directory. 322 os::close(fd); 323 return dirp; 324 } 325 326 // Open the directory. 327 dirp = ::opendir(dirname); 328 if (dirp == NULL) { 329 // The directory doesn't exist, close fd and return. 330 os::close(fd); 331 return dirp; 332 } 333 334 // Check to make sure fd and dirp are referencing the same file system object. 335 if (!is_same_fsobject(fd, dirfd(dirp))) { 336 // The directory is not secure. 337 os::close(fd); 338 os::closedir(dirp); 339 dirp = NULL; 340 return dirp; 341 } 342 343 // Close initial open now that we know directory is secure 344 os::close(fd); 345 346 return dirp; 347 } 348 349 // NOTE: The code below uses fchdir(), open() and unlink() because 350 // fdopendir(), openat() and unlinkat() are not supported on all 351 // versions. Once the support for fdopendir(), openat() and unlinkat() 352 // is available on all supported versions the code can be changed 353 // to use these functions. 354 355 // Open the directory of the given path, validate it and set the 356 // current working directory to it. 357 // Return a DIR * of the open directory and the saved cwd fd. 358 // 359 static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) { 360 361 // Open the directory. 362 DIR* dirp = open_directory_secure(dirname); 363 if (dirp == NULL) { 364 // Directory doesn't exist or is insecure, so there is nothing to cleanup. 365 return dirp; 366 } 367 int fd = dirfd(dirp); 368 369 // Open a fd to the cwd and save it off. 370 int result; 371 RESTARTABLE(::open(".", O_RDONLY), result); 372 if (result == OS_ERR) { 373 *saved_cwd_fd = -1; 374 } else { 375 *saved_cwd_fd = result; 376 } 377 378 // Set the current directory to dirname by using the fd of the directory and 379 // handle errors, otherwise shared memory files will be created in cwd. 380 result = fchdir(fd); 381 if (result == OS_ERR) { 382 if (PrintMiscellaneous && Verbose) { 383 warning("could not change to directory %s", dirname); 384 } 385 if (*saved_cwd_fd != -1) { 386 ::close(*saved_cwd_fd); 387 *saved_cwd_fd = -1; 388 } 389 // Close the directory. 390 os::closedir(dirp); 391 return NULL; 392 } else { 393 return dirp; 394 } 395 } 396 397 // Close the directory and restore the current working directory. 398 // 399 static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) { 400 401 int result; 402 // If we have a saved cwd change back to it and close the fd. 403 if (saved_cwd_fd != -1) { 404 result = fchdir(saved_cwd_fd); 405 ::close(saved_cwd_fd); 406 } 407 408 // Close the directory. 409 os::closedir(dirp); 410 } 411 412 // Check if the given file descriptor is considered a secure. 413 // 414 static bool is_file_secure(int fd, const char *filename) { 415 416 int result; 417 struct stat statbuf; 418 419 // Determine if the file is secure. 420 RESTARTABLE(::fstat(fd, &statbuf), result); 421 if (result == OS_ERR) { 422 if (PrintMiscellaneous && Verbose) { 423 warning("fstat failed on %s: %s\n", filename, strerror(errno)); 424 } 425 return false; 426 } 427 if (statbuf.st_nlink > 1) { 428 // A file with multiple links is not expected. 429 if (PrintMiscellaneous && Verbose) { 430 warning("file %s has multiple links\n", filename); 431 } 432 return false; 433 } 434 return true; 435 } 436 437 // return the user name for the given user id 438 // 439 // the caller is expected to free the allocated memory. 440 // 441 static char* get_user_name(uid_t uid) { 442 443 struct passwd pwent; 444 445 // determine the max pwbuf size from sysconf, and hardcode 446 // a default if this not available through sysconf. 447 // 448 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); 449 if (bufsize == -1) 450 bufsize = 1024; 451 452 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 453 454 // POSIX interface to getpwuid_r is used on LINUX 455 struct passwd* p; 456 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 457 458 if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 459 if (PrintMiscellaneous && Verbose) { 460 if (result != 0) { 461 warning("Could not retrieve passwd entry: %s\n", 462 strerror(result)); 463 } 464 else if (p == NULL) { 465 // this check is added to protect against an observed problem 466 // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0, 467 // indicating success, but has p == NULL. This was observed when 468 // inserting a file descriptor exhaustion fault prior to the call 469 // getpwuid_r() call. In this case, error is set to the appropriate 470 // error condition, but this is undocumented behavior. This check 471 // is safe under any condition, but the use of errno in the output 472 // message may result in an erroneous message. 473 // Bug Id 89052 was opened with RedHat. 474 // 475 warning("Could not retrieve passwd entry: %s\n", 476 strerror(errno)); 477 } 478 else { 479 warning("Could not determine user name: %s\n", 480 p->pw_name == NULL ? "pw_name = NULL" : 481 "pw_name zero length"); 482 } 483 } 484 FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal); 485 return NULL; 486 } 487 488 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal); 489 strcpy(user_name, p->pw_name); 490 491 FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal); 492 return user_name; 493 } 494 495 // return the name of the user that owns the process identified by vmid. 496 // 497 // This method uses a slow directory search algorithm to find the backing 498 // store file for the specified vmid and returns the user name, as determined 499 // by the user name suffix of the hsperfdata_<username> directory name. 500 // 501 // the caller is expected to free the allocated memory. 502 // 503 static char* get_user_name_slow(int vmid, TRAPS) { 504 505 // short circuit the directory search if the process doesn't even exist. 506 if (kill(vmid, 0) == OS_ERR) { 507 if (errno == ESRCH) { 508 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 509 "Process not found"); 510 } 511 else /* EPERM */ { 512 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno)); 513 } 514 } 515 516 // directory search 517 char* oldest_user = NULL; 518 time_t oldest_ctime = 0; 519 520 const char* tmpdirname = os::get_temp_directory(); 521 522 // open the temp directory 523 DIR* tmpdirp = os::opendir(tmpdirname); 524 525 if (tmpdirp == NULL) { 526 // Cannot open the directory to get the user name, return. 527 return NULL; 528 } 529 530 // for each entry in the directory that matches the pattern hsperfdata_*, 531 // open the directory and check if the file for the given vmid exists. 532 // The file with the expected name and the latest creation date is used 533 // to determine the user name for the process id. 534 // 535 struct dirent* dentry; 536 errno = 0; 537 while ((dentry = os::readdir(tmpdirp)) != NULL) { 538 539 // check if the directory entry is a hsperfdata file 540 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { 541 continue; 542 } 543 544 char* usrdir_name = NEW_C_HEAP_ARRAY(char, 545 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal); 546 strcpy(usrdir_name, tmpdirname); 547 strcat(usrdir_name, "/"); 548 strcat(usrdir_name, dentry->d_name); 549 550 // open the user directory 551 DIR* subdirp = open_directory_secure(usrdir_name); 552 553 if (subdirp == NULL) { 554 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); 555 continue; 556 } 557 558 struct dirent* udentry; 559 errno = 0; 560 while ((udentry = os::readdir(subdirp)) != NULL) { 561 562 if (filename_to_pid(udentry->d_name) == vmid) { 563 struct stat statbuf; 564 int result; 565 566 char* filename = NEW_C_HEAP_ARRAY(char, 567 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal); 568 569 strcpy(filename, usrdir_name); 570 strcat(filename, "/"); 571 strcat(filename, udentry->d_name); 572 573 // don't follow symbolic links for the file 574 RESTARTABLE(::lstat(filename, &statbuf), result); 575 if (result == OS_ERR) { 576 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 577 continue; 578 } 579 580 // skip over files that are not regular files. 581 if (!S_ISREG(statbuf.st_mode)) { 582 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 583 continue; 584 } 585 586 // compare and save filename with latest creation time 587 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { 588 589 if (statbuf.st_ctime > oldest_ctime) { 590 char* user = strchr(dentry->d_name, '_') + 1; 591 592 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user, mtInternal); 593 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal); 594 595 strcpy(oldest_user, user); 596 oldest_ctime = statbuf.st_ctime; 597 } 598 } 599 600 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 601 } 602 } 603 os::closedir(subdirp); 604 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); 605 } 606 os::closedir(tmpdirp); 607 608 return(oldest_user); 609 } 610 611 // return the name of the user that owns the JVM indicated by the given vmid. 612 // 613 static char* get_user_name(int vmid, TRAPS) { 614 return get_user_name_slow(vmid, CHECK_NULL); 615 } 616 617 // return the file name of the backing store file for the named 618 // shared memory region for the given user name and vmid. 619 // 620 // the caller is expected to free the allocated memory. 621 // 622 static char* get_sharedmem_filename(const char* dirname, int vmid) { 623 624 // add 2 for the file separator and a null terminator. 625 size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 626 627 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 628 snprintf(name, nbytes, "%s/%d", dirname, vmid); 629 630 return name; 631 } 632 633 634 // remove file 635 // 636 // this method removes the file specified by the given path 637 // 638 static void remove_file(const char* path) { 639 640 int result; 641 642 // if the file is a directory, the following unlink will fail. since 643 // we don't expect to find directories in the user temp directory, we 644 // won't try to handle this situation. even if accidentially or 645 // maliciously planted, the directory's presence won't hurt anything. 646 // 647 RESTARTABLE(::unlink(path), result); 648 if (PrintMiscellaneous && Verbose && result == OS_ERR) { 649 if (errno != ENOENT) { 650 warning("Could not unlink shared memory backing" 651 " store file %s : %s\n", path, strerror(errno)); 652 } 653 } 654 } 655 656 657 // cleanup stale shared memory resources 658 // 659 // This method attempts to remove all stale shared memory files in 660 // the named user temporary directory. It scans the named directory 661 // for files matching the pattern ^$[0-9]*$. For each file found, the 662 // process id is extracted from the file name and a test is run to 663 // determine if the process is alive. If the process is not alive, 664 // any stale file resources are removed. 665 // 666 static void cleanup_sharedmem_resources(const char* dirname) { 667 668 int saved_cwd_fd; 669 // open the directory and set the current working directory to it 670 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 671 if (dirp == NULL) { 672 // directory doesn't exist or is insecure, so there is nothing to cleanup 673 return; 674 } 675 676 // for each entry in the directory that matches the expected file 677 // name pattern, determine if the file resources are stale and if 678 // so, remove the file resources. Note, instrumented HotSpot processes 679 // for this user may start and/or terminate during this search and 680 // remove or create new files in this directory. The behavior of this 681 // loop under these conditions is dependent upon the implementation of 682 // opendir/readdir. 683 // 684 struct dirent* entry; 685 errno = 0; 686 while ((entry = os::readdir(dirp)) != NULL) { 687 688 pid_t pid = filename_to_pid(entry->d_name); 689 690 if (pid == 0) { 691 692 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 693 694 // attempt to remove all unexpected files, except "." and ".." 695 unlink(entry->d_name); 696 } 697 698 errno = 0; 699 continue; 700 } 701 702 // we now have a file name that converts to a valid integer 703 // that could represent a process id . if this process id 704 // matches the current process id or the process is not running, 705 // then remove the stale file resources. 706 // 707 // process liveness is detected by sending signal number 0 to 708 // the process id (see kill(2)). if kill determines that the 709 // process does not exist, then the file resources are removed. 710 // if kill determines that that we don't have permission to 711 // signal the process, then the file resources are assumed to 712 // be stale and are removed because the resources for such a 713 // process should be in a different user specific directory. 714 // 715 if ((pid == os::current_process_id()) || 716 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 717 718 unlink(entry->d_name); 719 } 720 errno = 0; 721 } 722 723 // close the directory and reset the current working directory 724 close_directory_secure_cwd(dirp, saved_cwd_fd); 725 } 726 727 // make the user specific temporary directory. Returns true if 728 // the directory exists and is secure upon return. Returns false 729 // if the directory exists but is either a symlink, is otherwise 730 // insecure, or if an error occurred. 731 // 732 static bool make_user_tmp_dir(const char* dirname) { 733 734 // create the directory with 0755 permissions. note that the directory 735 // will be owned by euid::egid, which may not be the same as uid::gid. 736 // 737 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 738 if (errno == EEXIST) { 739 // The directory already exists and was probably created by another 740 // JVM instance. However, this could also be the result of a 741 // deliberate symlink. Verify that the existing directory is safe. 742 // 743 if (!is_directory_secure(dirname)) { 744 // directory is not secure 745 if (PrintMiscellaneous && Verbose) { 746 warning("%s directory is insecure\n", dirname); 747 } 748 return false; 749 } 750 } 751 else { 752 // we encountered some other failure while attempting 753 // to create the directory 754 // 755 if (PrintMiscellaneous && Verbose) { 756 warning("could not create directory %s: %s\n", 757 dirname, strerror(errno)); 758 } 759 return false; 760 } 761 } 762 return true; 763 } 764 765 // create the shared memory file resources 766 // 767 // This method creates the shared memory file with the given size 768 // This method also creates the user specific temporary directory, if 769 // it does not yet exist. 770 // 771 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 772 773 // make the user temporary directory 774 if (!make_user_tmp_dir(dirname)) { 775 // could not make/find the directory or the found directory 776 // was not secure 777 return -1; 778 } 779 780 int saved_cwd_fd; 781 // open the directory and set the current working directory to it 782 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 783 if (dirp == NULL) { 784 // Directory doesn't exist or is insecure, so cannot create shared 785 // memory file. 786 return -1; 787 } 788 789 // Open the filename in the current directory. 790 // Cannot use O_TRUNC here; truncation of an existing file has to happen 791 // after the is_file_secure() check below. 792 int result; 793 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result); 794 if (result == OS_ERR) { 795 if (PrintMiscellaneous && Verbose) { 796 if (errno == ELOOP) { 797 warning("file %s is a symlink and is not secure\n", filename); 798 } else { 799 warning("could not create file %s: %s\n", filename, strerror(errno)); 800 } 801 } 802 // close the directory and reset the current working directory 803 close_directory_secure_cwd(dirp, saved_cwd_fd); 804 805 return -1; 806 } 807 // close the directory and reset the current working directory 808 close_directory_secure_cwd(dirp, saved_cwd_fd); 809 810 // save the file descriptor 811 int fd = result; 812 813 // check to see if the file is secure 814 if (!is_file_secure(fd, filename)) { 815 ::close(fd); 816 return -1; 817 } 818 819 // truncate the file to get rid of any existing data 820 RESTARTABLE(::ftruncate(fd, (off_t)0), result); 821 if (result == OS_ERR) { 822 if (PrintMiscellaneous && Verbose) { 823 warning("could not truncate shared memory file: %s\n", strerror(errno)); 824 } 825 ::close(fd); 826 return -1; 827 } 828 // set the file size 829 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 830 if (result == OS_ERR) { 831 if (PrintMiscellaneous && Verbose) { 832 warning("could not set shared memory file size: %s\n", strerror(errno)); 833 } 834 ::close(fd); 835 return -1; 836 } 837 838 // Verify that we have enough disk space for this file. 839 // We'll get random SIGBUS crashes on memory accesses if 840 // we don't. 841 842 for (size_t seekpos = 0; seekpos < size; seekpos += os::vm_page_size()) { 843 int zero_int = 0; 844 result = (int)os::seek_to_file_offset(fd, (jlong)(seekpos)); 845 if (result == -1 ) break; 846 RESTARTABLE(::write(fd, &zero_int, 1), result); 847 if (result != 1) { 848 if (errno == ENOSPC) { 849 warning("Insufficient space for shared memory file:\n %s\nTry using the -Djava.io.tmpdir= option to select an alternate temp location.\n", filename); 850 } 851 break; 852 } 853 } 854 855 if (result != -1) { 856 return fd; 857 } else { 858 ::close(fd); 859 return -1; 860 } 861 } 862 863 // open the shared memory file for the given user and vmid. returns 864 // the file descriptor for the open file or -1 if the file could not 865 // be opened. 866 // 867 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 868 869 // open the file 870 int result; 871 RESTARTABLE(::open(filename, oflags), result); 872 if (result == OS_ERR) { 873 if (errno == ENOENT) { 874 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 875 "Process not found", OS_ERR); 876 } 877 else if (errno == EACCES) { 878 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 879 "Permission denied", OS_ERR); 880 } 881 else { 882 THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR); 883 } 884 } 885 int fd = result; 886 887 // check to see if the file is secure 888 if (!is_file_secure(fd, filename)) { 889 ::close(fd); 890 return -1; 891 } 892 893 return fd; 894 } 895 896 // create a named shared memory region. returns the address of the 897 // memory region on success or NULL on failure. A return value of 898 // NULL will ultimately disable the shared memory feature. 899 // 900 // On Solaris and Bsd, the name space for shared memory objects 901 // is the file system name space. 902 // 903 // A monitoring application attaching to a JVM does not need to know 904 // the file system name of the shared memory object. However, it may 905 // be convenient for applications to discover the existence of newly 906 // created and terminating JVMs by watching the file system name space 907 // for files being created or removed. 908 // 909 static char* mmap_create_shared(size_t size) { 910 911 int result; 912 int fd; 913 char* mapAddress; 914 915 int vmid = os::current_process_id(); 916 917 char* user_name = get_user_name(geteuid()); 918 919 if (user_name == NULL) 920 return NULL; 921 922 char* dirname = get_user_tmp_dir(user_name); 923 char* filename = get_sharedmem_filename(dirname, vmid); 924 925 // get the short filename 926 char* short_filename = strrchr(filename, '/'); 927 if (short_filename == NULL) { 928 short_filename = filename; 929 } else { 930 short_filename++; 931 } 932 933 // cleanup any stale shared memory files 934 cleanup_sharedmem_resources(dirname); 935 936 assert(((size > 0) && (size % os::vm_page_size() == 0)), 937 "unexpected PerfMemory region size"); 938 939 fd = create_sharedmem_resources(dirname, short_filename, size); 940 941 FREE_C_HEAP_ARRAY(char, user_name, mtInternal); 942 FREE_C_HEAP_ARRAY(char, dirname, mtInternal); 943 944 if (fd == -1) { 945 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 946 return NULL; 947 } 948 949 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 950 951 result = ::close(fd); 952 assert(result != OS_ERR, "could not close file"); 953 954 if (mapAddress == MAP_FAILED) { 955 if (PrintMiscellaneous && Verbose) { 956 warning("mmap failed - %s\n", strerror(errno)); 957 } 958 remove_file(filename); 959 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 960 return NULL; 961 } 962 963 // save the file name for use in delete_shared_memory() 964 backing_store_file_name = filename; 965 966 // clear the shared memory region 967 (void)::memset((void*) mapAddress, 0, size); 968 969 // it does not go through os api, the operation has to record from here 970 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal); 971 972 return mapAddress; 973 } 974 975 // release a named shared memory region 976 // 977 static void unmap_shared(char* addr, size_t bytes) { 978 os::release_memory(addr, bytes); 979 } 980 981 // create the PerfData memory region in shared memory. 982 // 983 static char* create_shared_memory(size_t size) { 984 985 // create the shared memory region. 986 return mmap_create_shared(size); 987 } 988 989 // delete the shared PerfData memory region 990 // 991 static void delete_shared_memory(char* addr, size_t size) { 992 993 // cleanup the persistent shared memory resources. since DestroyJavaVM does 994 // not support unloading of the JVM, unmapping of the memory resource is 995 // not performed. The memory will be reclaimed by the OS upon termination of 996 // the process. The backing store file is deleted from the file system. 997 998 assert(!PerfDisableSharedMem, "shouldn't be here"); 999 1000 if (backing_store_file_name != NULL) { 1001 remove_file(backing_store_file_name); 1002 // Don't.. Free heap memory could deadlock os::abort() if it is called 1003 // from signal handler. OS will reclaim the heap memory. 1004 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 1005 backing_store_file_name = NULL; 1006 } 1007 } 1008 1009 // return the size of the file for the given file descriptor 1010 // or 0 if it is not a valid size for a shared memory file 1011 // 1012 static size_t sharedmem_filesize(int fd, TRAPS) { 1013 1014 struct stat statbuf; 1015 int result; 1016 1017 RESTARTABLE(::fstat(fd, &statbuf), result); 1018 if (result == OS_ERR) { 1019 if (PrintMiscellaneous && Verbose) { 1020 warning("fstat failed: %s\n", strerror(errno)); 1021 } 1022 THROW_MSG_0(vmSymbols::java_io_IOException(), 1023 "Could not determine PerfMemory size"); 1024 } 1025 1026 if ((statbuf.st_size == 0) || 1027 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 1028 THROW_MSG_0(vmSymbols::java_lang_Exception(), 1029 "Invalid PerfMemory size"); 1030 } 1031 1032 return (size_t)statbuf.st_size; 1033 } 1034 1035 // attach to a named shared memory region. 1036 // 1037 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 1038 1039 char* mapAddress; 1040 int result; 1041 int fd; 1042 size_t size = 0; 1043 const char* luser = NULL; 1044 1045 int mmap_prot; 1046 int file_flags; 1047 1048 ResourceMark rm; 1049 1050 // map the high level access mode to the appropriate permission 1051 // constructs for the file and the shared memory mapping. 1052 if (mode == PerfMemory::PERF_MODE_RO) { 1053 mmap_prot = PROT_READ; 1054 file_flags = O_RDONLY | O_NOFOLLOW; 1055 } 1056 else if (mode == PerfMemory::PERF_MODE_RW) { 1057 #ifdef LATER 1058 mmap_prot = PROT_READ | PROT_WRITE; 1059 file_flags = O_RDWR | O_NOFOLLOW; 1060 #else 1061 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1062 "Unsupported access mode"); 1063 #endif 1064 } 1065 else { 1066 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1067 "Illegal access mode"); 1068 } 1069 1070 if (user == NULL || strlen(user) == 0) { 1071 luser = get_user_name(vmid, CHECK); 1072 } 1073 else { 1074 luser = user; 1075 } 1076 1077 if (luser == NULL) { 1078 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1079 "Could not map vmid to user Name"); 1080 } 1081 1082 char* dirname = get_user_tmp_dir(luser); 1083 1084 // since we don't follow symbolic links when creating the backing 1085 // store file, we don't follow them when attaching either. 1086 // 1087 if (!is_directory_secure(dirname)) { 1088 FREE_C_HEAP_ARRAY(char, dirname, mtInternal); 1089 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1090 "Process not found"); 1091 } 1092 1093 char* filename = get_sharedmem_filename(dirname, vmid); 1094 1095 // copy heap memory to resource memory. the open_sharedmem_file 1096 // method below need to use the filename, but could throw an 1097 // exception. using a resource array prevents the leak that 1098 // would otherwise occur. 1099 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); 1100 strcpy(rfilename, filename); 1101 1102 // free the c heap resources that are no longer needed 1103 if (luser != user) FREE_C_HEAP_ARRAY(char, luser, mtInternal); 1104 FREE_C_HEAP_ARRAY(char, dirname, mtInternal); 1105 FREE_C_HEAP_ARRAY(char, filename, mtInternal); 1106 1107 // open the shared memory file for the give vmid 1108 fd = open_sharedmem_file(rfilename, file_flags, CHECK); 1109 assert(fd != OS_ERR, "unexpected value"); 1110 1111 if (*sizep == 0) { 1112 size = sharedmem_filesize(fd, CHECK); 1113 } else { 1114 size = *sizep; 1115 } 1116 1117 assert(size > 0, "unexpected size <= 0"); 1118 1119 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 1120 1121 // attempt to close the file - restart if it gets interrupted, 1122 // but ignore other failures 1123 result = ::close(fd); 1124 assert(result != OS_ERR, "could not close file"); 1125 1126 if (mapAddress == MAP_FAILED) { 1127 if (PrintMiscellaneous && Verbose) { 1128 warning("mmap failed: %s\n", strerror(errno)); 1129 } 1130 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 1131 "Could not map PerfMemory"); 1132 } 1133 1134 // it does not go through os api, the operation has to record from here 1135 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal); 1136 1137 *addr = mapAddress; 1138 *sizep = size; 1139 1140 if (PerfTraceMemOps) { 1141 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at " 1142 INTPTR_FORMAT "\n", size, vmid, p2i((void*)mapAddress)); 1143 } 1144 } 1145 1146 1147 1148 1149 // create the PerfData memory region 1150 // 1151 // This method creates the memory region used to store performance 1152 // data for the JVM. The memory may be created in standard or 1153 // shared memory. 1154 // 1155 void PerfMemory::create_memory_region(size_t size) { 1156 1157 if (PerfDisableSharedMem) { 1158 // do not share the memory for the performance data. 1159 _start = create_standard_memory(size); 1160 } 1161 else { 1162 _start = create_shared_memory(size); 1163 if (_start == NULL) { 1164 1165 // creation of the shared memory region failed, attempt 1166 // to create a contiguous, non-shared memory region instead. 1167 // 1168 if (PrintMiscellaneous && Verbose) { 1169 warning("Reverting to non-shared PerfMemory region.\n"); 1170 } 1171 PerfDisableSharedMem = true; 1172 _start = create_standard_memory(size); 1173 } 1174 } 1175 1176 if (_start != NULL) _capacity = size; 1177 1178 } 1179 1180 // delete the PerfData memory region 1181 // 1182 // This method deletes the memory region used to store performance 1183 // data for the JVM. The memory region indicated by the <address, size> 1184 // tuple will be inaccessible after a call to this method. 1185 // 1186 void PerfMemory::delete_memory_region() { 1187 1188 assert((start() != NULL && capacity() > 0), "verify proper state"); 1189 1190 // If user specifies PerfDataSaveFile, it will save the performance data 1191 // to the specified file name no matter whether PerfDataSaveToFile is specified 1192 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 1193 // -XX:+PerfDataSaveToFile. 1194 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 1195 save_memory_to_file(start(), capacity()); 1196 } 1197 1198 if (PerfDisableSharedMem) { 1199 delete_standard_memory(start(), capacity()); 1200 } 1201 else { 1202 delete_shared_memory(start(), capacity()); 1203 } 1204 } 1205 1206 // attach to the PerfData memory region for another JVM 1207 // 1208 // This method returns an <address, size> tuple that points to 1209 // a memory buffer that is kept reasonably synchronized with 1210 // the PerfData memory region for the indicated JVM. This 1211 // buffer may be kept in synchronization via shared memory 1212 // or some other mechanism that keeps the buffer updated. 1213 // 1214 // If the JVM chooses not to support the attachability feature, 1215 // this method should throw an UnsupportedOperation exception. 1216 // 1217 // This implementation utilizes named shared memory to map 1218 // the indicated process's PerfData memory region into this JVMs 1219 // address space. 1220 // 1221 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1222 1223 if (vmid == 0 || vmid == os::current_process_id()) { 1224 *addrp = start(); 1225 *sizep = capacity(); 1226 return; 1227 } 1228 1229 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1230 } 1231 1232 // detach from the PerfData memory region of another JVM 1233 // 1234 // This method detaches the PerfData memory region of another 1235 // JVM, specified as an <address, size> tuple of a buffer 1236 // in this process's address space. This method may perform 1237 // arbitrary actions to accomplish the detachment. The memory 1238 // region specified by <address, size> will be inaccessible after 1239 // a call to this method. 1240 // 1241 // If the JVM chooses not to support the attachability feature, 1242 // this method should throw an UnsupportedOperation exception. 1243 // 1244 // This implementation utilizes named shared memory to detach 1245 // the indicated process's PerfData memory region from this 1246 // process's address space. 1247 // 1248 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1249 1250 assert(addr != 0, "address sanity check"); 1251 assert(bytes > 0, "capacity sanity check"); 1252 1253 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1254 // prevent accidental detachment of this process's PerfMemory region 1255 return; 1256 } 1257 1258 unmap_shared(addr, bytes); 1259 } 1260 1261 char* PerfMemory::backing_store_filename() { 1262 return backing_store_file_name; 1263 }