1 /* 2 * Copyright (c) 2001, 2018, 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 "logging/log.hpp" 28 #include "memory/allocation.inline.hpp" 29 #include "memory/resourceArea.hpp" 30 #include "oops/oop.inline.hpp" 31 #include "os_bsd.inline.hpp" 32 #include "runtime/handles.inline.hpp" 33 #include "runtime/os.hpp" 34 #include "runtime/perfMemory.hpp" 35 #include "services/memTracker.hpp" 36 #include "utilities/exceptions.hpp" 37 38 // put OS-includes here 39 # include <sys/types.h> 40 # include <sys/mman.h> 41 # include <errno.h> 42 # include <stdio.h> 43 # include <unistd.h> 44 # include <sys/stat.h> 45 # include <signal.h> 46 # include <pwd.h> 47 48 static 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 // 55 static 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 // 78 static 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 // 93 static void save_memory_to_file(char* addr, size_t size) { 94 95 const char* destfile = PerfMemory::get_perfdata_file_path(); 96 assert(destfile[0] != '\0', "invalid PerfData file path"); 97 98 int result; 99 100 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), 101 result);; 102 if (result == OS_ERR) { 103 if (PrintMiscellaneous && Verbose) { 104 warning("Could not create Perfdata save file: %s: %s\n", 105 destfile, os::strerror(errno)); 106 } 107 } else { 108 int fd = result; 109 110 for (size_t remaining = size; remaining > 0;) { 111 112 RESTARTABLE(::write(fd, addr, remaining), result); 113 if (result == OS_ERR) { 114 if (PrintMiscellaneous && Verbose) { 115 warning("Could not write Perfdata save file: %s: %s\n", 116 destfile, os::strerror(errno)); 117 } 118 break; 119 } 120 121 remaining -= (size_t)result; 122 addr += result; 123 } 124 125 result = ::close(fd); 126 if (PrintMiscellaneous && Verbose) { 127 if (result == OS_ERR) { 128 warning("Could not close %s: %s\n", destfile, os::strerror(errno)); 129 } 130 } 131 } 132 FREE_C_HEAP_ARRAY(char, destfile); 133 } 134 135 136 // Shared Memory Implementation Details 137 138 // Note: the solaris and bsd 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 bsd 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 // 154 static 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 // 170 static 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 // 207 static 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 // 238 static 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 // 257 static 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 // 273 static 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 // 299 static 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, dirfd(dirp))) { 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 // 361 static 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 = dirfd(dirp); 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 // 401 static 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 // 416 static 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 // 443 static 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 // POSIX interface to getpwuid_r is used on LINUX 457 struct passwd* p; 458 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 459 460 if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 461 if (PrintMiscellaneous && Verbose) { 462 if (result != 0) { 463 warning("Could not retrieve passwd entry: %s\n", 464 os::strerror(result)); 465 } 466 else if (p == NULL) { 467 // this check is added to protect against an observed problem 468 // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0, 469 // indicating success, but has p == NULL. This was observed when 470 // inserting a file descriptor exhaustion fault prior to the call 471 // getpwuid_r() call. In this case, error is set to the appropriate 472 // error condition, but this is undocumented behavior. This check 473 // is safe under any condition, but the use of errno in the output 474 // message may result in an erroneous message. 475 // Bug Id 89052 was opened with RedHat. 476 // 477 warning("Could not retrieve passwd entry: %s\n", 478 os::strerror(errno)); 479 } 480 else { 481 warning("Could not determine user name: %s\n", 482 p->pw_name == NULL ? "pw_name = NULL" : 483 "pw_name zero length"); 484 } 485 } 486 FREE_C_HEAP_ARRAY(char, pwbuf); 487 return NULL; 488 } 489 490 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal); 491 strcpy(user_name, p->pw_name); 492 493 FREE_C_HEAP_ARRAY(char, pwbuf); 494 return user_name; 495 } 496 497 // return the name of the user that owns the process identified by vmid. 498 // 499 // This method uses a slow directory search algorithm to find the backing 500 // store file for the specified vmid and returns the user name, as determined 501 // by the user name suffix of the hsperfdata_<username> directory name. 502 // 503 // the caller is expected to free the allocated memory. 504 // 505 static char* get_user_name_slow(int vmid, TRAPS) { 506 507 // short circuit the directory search if the process doesn't even exist. 508 if (kill(vmid, 0) == OS_ERR) { 509 if (errno == ESRCH) { 510 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 511 "Process not found"); 512 } 513 else /* EPERM */ { 514 THROW_MSG_0(vmSymbols::java_io_IOException(), os::strerror(errno)); 515 } 516 } 517 518 // directory search 519 char* oldest_user = NULL; 520 time_t oldest_ctime = 0; 521 522 const char* tmpdirname = os::get_temp_directory(); 523 524 // open the temp directory 525 DIR* tmpdirp = os::opendir(tmpdirname); 526 527 if (tmpdirp == NULL) { 528 // Cannot open the directory to get the user name, return. 529 return NULL; 530 } 531 532 // for each entry in the directory that matches the pattern hsperfdata_*, 533 // open the directory and check if the file for the given vmid exists. 534 // The file with the expected name and the latest creation date is used 535 // to determine the user name for the process id. 536 // 537 struct dirent* dentry; 538 errno = 0; 539 while ((dentry = os::readdir(tmpdirp)) != NULL) { 540 541 // check if the directory entry is a hsperfdata file 542 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { 543 continue; 544 } 545 546 char* usrdir_name = NEW_C_HEAP_ARRAY(char, 547 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal); 548 strcpy(usrdir_name, tmpdirname); 549 strcat(usrdir_name, "/"); 550 strcat(usrdir_name, dentry->d_name); 551 552 // open the user directory 553 DIR* subdirp = open_directory_secure(usrdir_name); 554 555 if (subdirp == NULL) { 556 FREE_C_HEAP_ARRAY(char, usrdir_name); 557 continue; 558 } 559 560 struct dirent* udentry; 561 errno = 0; 562 while ((udentry = os::readdir(subdirp)) != NULL) { 563 564 if (filename_to_pid(udentry->d_name) == vmid) { 565 struct stat statbuf; 566 int result; 567 568 char* filename = NEW_C_HEAP_ARRAY(char, 569 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal); 570 571 strcpy(filename, usrdir_name); 572 strcat(filename, "/"); 573 strcat(filename, udentry->d_name); 574 575 // don't follow symbolic links for the file 576 RESTARTABLE(::lstat(filename, &statbuf), result); 577 if (result == OS_ERR) { 578 FREE_C_HEAP_ARRAY(char, filename); 579 continue; 580 } 581 582 // skip over files that are not regular files. 583 if (!S_ISREG(statbuf.st_mode)) { 584 FREE_C_HEAP_ARRAY(char, filename); 585 continue; 586 } 587 588 // compare and save filename with latest creation time 589 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { 590 591 if (statbuf.st_ctime > oldest_ctime) { 592 char* user = strchr(dentry->d_name, '_') + 1; 593 594 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user); 595 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal); 596 597 strcpy(oldest_user, user); 598 oldest_ctime = statbuf.st_ctime; 599 } 600 } 601 602 FREE_C_HEAP_ARRAY(char, filename); 603 } 604 } 605 os::closedir(subdirp); 606 FREE_C_HEAP_ARRAY(char, usrdir_name); 607 } 608 os::closedir(tmpdirp); 609 610 return(oldest_user); 611 } 612 613 // return the name of the user that owns the JVM indicated by the given vmid. 614 // 615 static char* get_user_name(int vmid, TRAPS) { 616 return get_user_name_slow(vmid, THREAD); 617 } 618 619 // return the file name of the backing store file for the named 620 // shared memory region for the given user name and vmid. 621 // 622 // the caller is expected to free the allocated memory. 623 // 624 static char* get_sharedmem_filename(const char* dirname, int vmid) { 625 626 // add 2 for the file separator and a null terminator. 627 size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 628 629 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 630 snprintf(name, nbytes, "%s/%d", dirname, vmid); 631 632 return name; 633 } 634 635 636 // remove file 637 // 638 // this method removes the file specified by the given path 639 // 640 static void remove_file(const char* path) { 641 642 int result; 643 644 // if the file is a directory, the following unlink will fail. since 645 // we don't expect to find directories in the user temp directory, we 646 // won't try to handle this situation. even if accidentially or 647 // maliciously planted, the directory's presence won't hurt anything. 648 // 649 RESTARTABLE(::unlink(path), result); 650 if (PrintMiscellaneous && Verbose && result == OS_ERR) { 651 if (errno != ENOENT) { 652 warning("Could not unlink shared memory backing" 653 " store file %s : %s\n", path, os::strerror(errno)); 654 } 655 } 656 } 657 658 659 // cleanup stale shared memory resources 660 // 661 // This method attempts to remove all stale shared memory files in 662 // the named user temporary directory. It scans the named directory 663 // for files matching the pattern ^$[0-9]*$. For each file found, the 664 // process id is extracted from the file name and a test is run to 665 // determine if the process is alive. If the process is not alive, 666 // any stale file resources are removed. 667 // 668 static void cleanup_sharedmem_resources(const char* dirname) { 669 670 int saved_cwd_fd; 671 // open the directory and set the current working directory to it 672 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 673 if (dirp == NULL) { 674 // directory doesn't exist or is insecure, so there is nothing to cleanup 675 return; 676 } 677 678 // for each entry in the directory that matches the expected file 679 // name pattern, determine if the file resources are stale and if 680 // so, remove the file resources. Note, instrumented HotSpot processes 681 // for this user may start and/or terminate during this search and 682 // remove or create new files in this directory. The behavior of this 683 // loop under these conditions is dependent upon the implementation of 684 // opendir/readdir. 685 // 686 struct dirent* entry; 687 errno = 0; 688 while ((entry = os::readdir(dirp)) != NULL) { 689 690 pid_t pid = filename_to_pid(entry->d_name); 691 692 if (pid == 0) { 693 694 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 695 696 // attempt to remove all unexpected files, except "." and ".." 697 unlink(entry->d_name); 698 } 699 700 errno = 0; 701 continue; 702 } 703 704 // we now have a file name that converts to a valid integer 705 // that could represent a process id . if this process id 706 // matches the current process id or the process is not running, 707 // then remove the stale file resources. 708 // 709 // process liveness is detected by sending signal number 0 to 710 // the process id (see kill(2)). if kill determines that the 711 // process does not exist, then the file resources are removed. 712 // if kill determines that that we don't have permission to 713 // signal the process, then the file resources are assumed to 714 // be stale and are removed because the resources for such a 715 // process should be in a different user specific directory. 716 // 717 if ((pid == os::current_process_id()) || 718 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 719 720 unlink(entry->d_name); 721 } 722 errno = 0; 723 } 724 725 // close the directory and reset the current working directory 726 close_directory_secure_cwd(dirp, saved_cwd_fd); 727 } 728 729 // make the user specific temporary directory. Returns true if 730 // the directory exists and is secure upon return. Returns false 731 // if the directory exists but is either a symlink, is otherwise 732 // insecure, or if an error occurred. 733 // 734 static bool make_user_tmp_dir(const char* dirname) { 735 736 // create the directory with 0755 permissions. note that the directory 737 // will be owned by euid::egid, which may not be the same as uid::gid. 738 // 739 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 740 if (errno == EEXIST) { 741 // The directory already exists and was probably created by another 742 // JVM instance. However, this could also be the result of a 743 // deliberate symlink. Verify that the existing directory is safe. 744 // 745 if (!is_directory_secure(dirname)) { 746 // directory is not secure 747 if (PrintMiscellaneous && Verbose) { 748 warning("%s directory is insecure\n", dirname); 749 } 750 return false; 751 } 752 } 753 else { 754 // we encountered some other failure while attempting 755 // to create the directory 756 // 757 if (PrintMiscellaneous && Verbose) { 758 warning("could not create directory %s: %s\n", 759 dirname, os::strerror(errno)); 760 } 761 return false; 762 } 763 } 764 return true; 765 } 766 767 // create the shared memory file resources 768 // 769 // This method creates the shared memory file with the given size 770 // This method also creates the user specific temporary directory, if 771 // it does not yet exist. 772 // 773 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 774 775 // make the user temporary directory 776 if (!make_user_tmp_dir(dirname)) { 777 // could not make/find the directory or the found directory 778 // was not secure 779 return -1; 780 } 781 782 int saved_cwd_fd; 783 // open the directory and set the current working directory to it 784 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 785 if (dirp == NULL) { 786 // Directory doesn't exist or is insecure, so cannot create shared 787 // memory file. 788 return -1; 789 } 790 791 // Open the filename in the current directory. 792 // Cannot use O_TRUNC here; truncation of an existing file has to happen 793 // after the is_file_secure() check below. 794 int result; 795 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result); 796 if (result == OS_ERR) { 797 if (PrintMiscellaneous && Verbose) { 798 if (errno == ELOOP) { 799 warning("file %s is a symlink and is not secure\n", filename); 800 } else { 801 warning("could not create file %s: %s\n", filename, os::strerror(errno)); 802 } 803 } 804 // close the directory and reset the current working directory 805 close_directory_secure_cwd(dirp, saved_cwd_fd); 806 807 return -1; 808 } 809 // close the directory and reset the current working directory 810 close_directory_secure_cwd(dirp, saved_cwd_fd); 811 812 // save the file descriptor 813 int fd = result; 814 815 // check to see if the file is secure 816 if (!is_file_secure(fd, filename)) { 817 ::close(fd); 818 return -1; 819 } 820 821 // truncate the file to get rid of any existing data 822 RESTARTABLE(::ftruncate(fd, (off_t)0), result); 823 if (result == OS_ERR) { 824 if (PrintMiscellaneous && Verbose) { 825 warning("could not truncate shared memory file: %s\n", os::strerror(errno)); 826 } 827 ::close(fd); 828 return -1; 829 } 830 // set the file size 831 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 832 if (result == OS_ERR) { 833 if (PrintMiscellaneous && Verbose) { 834 warning("could not set shared memory file size: %s\n", os::strerror(errno)); 835 } 836 ::close(fd); 837 return -1; 838 } 839 840 // Verify that we have enough disk space for this file. 841 // We'll get random SIGBUS crashes on memory accesses if 842 // we don't. 843 844 for (size_t seekpos = 0; seekpos < size; seekpos += os::vm_page_size()) { 845 int zero_int = 0; 846 result = (int)os::seek_to_file_offset(fd, (jlong)(seekpos)); 847 if (result == -1 ) break; 848 RESTARTABLE(::write(fd, &zero_int, 1), result); 849 if (result != 1) { 850 if (errno == ENOSPC) { 851 warning("Insufficient space for shared memory file:\n %s\nTry using the -Djava.io.tmpdir= option to select an alternate temp location.\n", filename); 852 } 853 break; 854 } 855 } 856 857 if (result != -1) { 858 return fd; 859 } else { 860 ::close(fd); 861 return -1; 862 } 863 } 864 865 // open the shared memory file for the given user and vmid. returns 866 // the file descriptor for the open file or -1 if the file could not 867 // be opened. 868 // 869 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 870 871 // open the file 872 int result; 873 RESTARTABLE(::open(filename, oflags), result); 874 if (result == OS_ERR) { 875 if (errno == ENOENT) { 876 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 877 "Process not found", OS_ERR); 878 } 879 else if (errno == EACCES) { 880 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 881 "Permission denied", OS_ERR); 882 } 883 else { 884 THROW_MSG_(vmSymbols::java_io_IOException(), 885 os::strerror(errno), OS_ERR); 886 } 887 } 888 int fd = result; 889 890 // check to see if the file is secure 891 if (!is_file_secure(fd, filename)) { 892 ::close(fd); 893 return -1; 894 } 895 896 return fd; 897 } 898 899 // create a named shared memory region. returns the address of the 900 // memory region on success or NULL on failure. A return value of 901 // NULL will ultimately disable the shared memory feature. 902 // 903 // On BSD, the name space for shared memory objects 904 // is the file system name space. 905 // 906 // A monitoring application attaching to a JVM does not need to know 907 // the file system name of the shared memory object. However, it may 908 // be convenient for applications to discover the existence of newly 909 // created and terminating JVMs by watching the file system name space 910 // for files being created or removed. 911 // 912 static char* mmap_create_shared(size_t size) { 913 914 int result; 915 int fd; 916 char* mapAddress; 917 918 int vmid = os::current_process_id(); 919 920 char* user_name = get_user_name(geteuid()); 921 922 if (user_name == NULL) 923 return NULL; 924 925 char* dirname = get_user_tmp_dir(user_name); 926 char* filename = get_sharedmem_filename(dirname, vmid); 927 928 // get the short filename 929 char* short_filename = strrchr(filename, '/'); 930 if (short_filename == NULL) { 931 short_filename = filename; 932 } else { 933 short_filename++; 934 } 935 936 // cleanup any stale shared memory files 937 cleanup_sharedmem_resources(dirname); 938 939 assert(((size > 0) && (size % os::vm_page_size() == 0)), 940 "unexpected PerfMemory region size"); 941 942 fd = create_sharedmem_resources(dirname, short_filename, size); 943 944 FREE_C_HEAP_ARRAY(char, user_name); 945 FREE_C_HEAP_ARRAY(char, dirname); 946 947 if (fd == -1) { 948 FREE_C_HEAP_ARRAY(char, filename); 949 return NULL; 950 } 951 952 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 953 954 result = ::close(fd); 955 assert(result != OS_ERR, "could not close file"); 956 957 if (mapAddress == MAP_FAILED) { 958 if (PrintMiscellaneous && Verbose) { 959 warning("mmap failed - %s\n", os::strerror(errno)); 960 } 961 remove_file(filename); 962 FREE_C_HEAP_ARRAY(char, filename); 963 return NULL; 964 } 965 966 // save the file name for use in delete_shared_memory() 967 backing_store_file_name = filename; 968 969 // clear the shared memory region 970 (void)::memset((void*) mapAddress, 0, size); 971 972 // it does not go through os api, the operation has to record from here 973 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal); 974 975 return mapAddress; 976 } 977 978 // release a named shared memory region 979 // 980 static void unmap_shared(char* addr, size_t bytes) { 981 os::release_memory(addr, bytes); 982 } 983 984 // create the PerfData memory region in shared memory. 985 // 986 static char* create_shared_memory(size_t size) { 987 988 // create the shared memory region. 989 return mmap_create_shared(size); 990 } 991 992 // delete the shared PerfData memory region 993 // 994 static void delete_shared_memory(char* addr, size_t size) { 995 996 // cleanup the persistent shared memory resources. since DestroyJavaVM does 997 // not support unloading of the JVM, unmapping of the memory resource is 998 // not performed. The memory will be reclaimed by the OS upon termination of 999 // the process. The backing store file is deleted from the file system. 1000 1001 assert(!PerfDisableSharedMem, "shouldn't be here"); 1002 1003 if (backing_store_file_name != NULL) { 1004 remove_file(backing_store_file_name); 1005 // Don't.. Free heap memory could deadlock os::abort() if it is called 1006 // from signal handler. OS will reclaim the heap memory. 1007 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 1008 backing_store_file_name = NULL; 1009 } 1010 } 1011 1012 // return the size of the file for the given file descriptor 1013 // or 0 if it is not a valid size for a shared memory file 1014 // 1015 static size_t sharedmem_filesize(int fd, TRAPS) { 1016 1017 struct stat statbuf; 1018 int result; 1019 1020 RESTARTABLE(::fstat(fd, &statbuf), result); 1021 if (result == OS_ERR) { 1022 if (PrintMiscellaneous && Verbose) { 1023 warning("fstat failed: %s\n", os::strerror(errno)); 1024 } 1025 THROW_MSG_0(vmSymbols::java_io_IOException(), 1026 "Could not determine PerfMemory size"); 1027 } 1028 1029 if ((statbuf.st_size == 0) || 1030 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 1031 THROW_MSG_0(vmSymbols::java_lang_Exception(), 1032 "Invalid PerfMemory size"); 1033 } 1034 1035 return (size_t)statbuf.st_size; 1036 } 1037 1038 // attach to a named shared memory region. 1039 // 1040 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 1041 1042 char* mapAddress; 1043 int result; 1044 int fd; 1045 size_t size = 0; 1046 const char* luser = NULL; 1047 1048 int mmap_prot; 1049 int file_flags; 1050 1051 ResourceMark rm; 1052 1053 // map the high level access mode to the appropriate permission 1054 // constructs for the file and the shared memory mapping. 1055 if (mode == PerfMemory::PERF_MODE_RO) { 1056 mmap_prot = PROT_READ; 1057 file_flags = O_RDONLY | O_NOFOLLOW; 1058 } 1059 else if (mode == PerfMemory::PERF_MODE_RW) { 1060 #ifdef LATER 1061 mmap_prot = PROT_READ | PROT_WRITE; 1062 file_flags = O_RDWR | O_NOFOLLOW; 1063 #else 1064 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1065 "Unsupported access mode"); 1066 #endif 1067 } 1068 else { 1069 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1070 "Illegal access mode"); 1071 } 1072 1073 if (user == NULL || strlen(user) == 0) { 1074 luser = get_user_name(vmid, CHECK); 1075 } 1076 else { 1077 luser = user; 1078 } 1079 1080 if (luser == NULL) { 1081 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1082 "Could not map vmid to user Name"); 1083 } 1084 1085 char* dirname = get_user_tmp_dir(luser); 1086 1087 // since we don't follow symbolic links when creating the backing 1088 // store file, we don't follow them when attaching either. 1089 // 1090 if (!is_directory_secure(dirname)) { 1091 FREE_C_HEAP_ARRAY(char, dirname); 1092 if (luser != user) { 1093 FREE_C_HEAP_ARRAY(char, luser); 1094 } 1095 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1096 "Process not found"); 1097 } 1098 1099 char* filename = get_sharedmem_filename(dirname, vmid); 1100 1101 // copy heap memory to resource memory. the open_sharedmem_file 1102 // method below need to use the filename, but could throw an 1103 // exception. using a resource array prevents the leak that 1104 // would otherwise occur. 1105 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); 1106 strcpy(rfilename, filename); 1107 1108 // free the c heap resources that are no longer needed 1109 if (luser != user) FREE_C_HEAP_ARRAY(char, luser); 1110 FREE_C_HEAP_ARRAY(char, dirname); 1111 FREE_C_HEAP_ARRAY(char, filename); 1112 1113 // open the shared memory file for the give vmid 1114 fd = open_sharedmem_file(rfilename, file_flags, CHECK); 1115 assert(fd != OS_ERR, "unexpected value"); 1116 1117 if (*sizep == 0) { 1118 size = sharedmem_filesize(fd, CHECK); 1119 } else { 1120 size = *sizep; 1121 } 1122 1123 assert(size > 0, "unexpected size <= 0"); 1124 1125 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 1126 1127 // attempt to close the file - restart if it gets interrupted, 1128 // but ignore other failures 1129 result = ::close(fd); 1130 assert(result != OS_ERR, "could not close file"); 1131 1132 if (mapAddress == MAP_FAILED) { 1133 if (PrintMiscellaneous && Verbose) { 1134 warning("mmap failed: %s\n", os::strerror(errno)); 1135 } 1136 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 1137 "Could not map PerfMemory"); 1138 } 1139 1140 // it does not go through os api, the operation has to record from here 1141 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal); 1142 1143 *addr = mapAddress; 1144 *sizep = size; 1145 1146 log_debug(perf, memops)("mapped " SIZE_FORMAT " bytes for vmid %d at " 1147 INTPTR_FORMAT, size, vmid, p2i((void*)mapAddress)); 1148 } 1149 1150 // create the PerfData memory region 1151 // 1152 // This method creates the memory region used to store performance 1153 // data for the JVM. The memory may be created in standard or 1154 // shared memory. 1155 // 1156 void PerfMemory::create_memory_region(size_t size) { 1157 1158 if (PerfDisableSharedMem) { 1159 // do not share the memory for the performance data. 1160 _start = create_standard_memory(size); 1161 } 1162 else { 1163 _start = create_shared_memory(size); 1164 if (_start == NULL) { 1165 1166 // creation of the shared memory region failed, attempt 1167 // to create a contiguous, non-shared memory region instead. 1168 // 1169 if (PrintMiscellaneous && Verbose) { 1170 warning("Reverting to non-shared PerfMemory region.\n"); 1171 } 1172 PerfDisableSharedMem = true; 1173 _start = create_standard_memory(size); 1174 } 1175 } 1176 1177 if (_start != NULL) _capacity = size; 1178 1179 } 1180 1181 // delete the PerfData memory region 1182 // 1183 // This method deletes the memory region used to store performance 1184 // data for the JVM. The memory region indicated by the <address, size> 1185 // tuple will be inaccessible after a call to this method. 1186 // 1187 void PerfMemory::delete_memory_region() { 1188 1189 assert((start() != NULL && capacity() > 0), "verify proper state"); 1190 1191 // If user specifies PerfDataSaveFile, it will save the performance data 1192 // to the specified file name no matter whether PerfDataSaveToFile is specified 1193 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 1194 // -XX:+PerfDataSaveToFile. 1195 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 1196 save_memory_to_file(start(), capacity()); 1197 } 1198 1199 if (PerfDisableSharedMem) { 1200 delete_standard_memory(start(), capacity()); 1201 } 1202 else { 1203 delete_shared_memory(start(), capacity()); 1204 } 1205 } 1206 1207 // attach to the PerfData memory region for another JVM 1208 // 1209 // This method returns an <address, size> tuple that points to 1210 // a memory buffer that is kept reasonably synchronized with 1211 // the PerfData memory region for the indicated JVM. This 1212 // buffer may be kept in synchronization via shared memory 1213 // or some other mechanism that keeps the buffer updated. 1214 // 1215 // If the JVM chooses not to support the attachability feature, 1216 // this method should throw an UnsupportedOperation exception. 1217 // 1218 // This implementation utilizes named shared memory to map 1219 // the indicated process's PerfData memory region into this JVMs 1220 // address space. 1221 // 1222 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1223 1224 if (vmid == 0 || vmid == os::current_process_id()) { 1225 *addrp = start(); 1226 *sizep = capacity(); 1227 return; 1228 } 1229 1230 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1231 } 1232 1233 // detach from the PerfData memory region of another JVM 1234 // 1235 // This method detaches the PerfData memory region of another 1236 // JVM, specified as an <address, size> tuple of a buffer 1237 // in this process's address space. This method may perform 1238 // arbitrary actions to accomplish the detachment. The memory 1239 // region specified by <address, size> will be inaccessible after 1240 // a call to this method. 1241 // 1242 // If the JVM chooses not to support the attachability feature, 1243 // this method should throw an UnsupportedOperation exception. 1244 // 1245 // This implementation utilizes named shared memory to detach 1246 // the indicated process's PerfData memory region from this 1247 // process's address space. 1248 // 1249 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1250 1251 assert(addr != 0, "address sanity check"); 1252 assert(bytes > 0, "capacity sanity check"); 1253 1254 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1255 // prevent accidental detachment of this process's PerfMemory region 1256 return; 1257 } 1258 1259 unmap_shared(addr, bytes); 1260 }