1 /* 2 * Copyright (c) 2001, 2019, 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_solaris.inline.hpp" 32 #include "runtime/handles.inline.hpp" 33 #include "runtime/perfMemory.hpp" 34 #include "services/memTracker.hpp" 35 #include "utilities/exceptions.hpp" 36 37 // put OS-includes here 38 #include <sys/types.h> 39 #include <sys/mman.h> 40 #include <errno.h> 41 #include <stdio.h> 42 #include <unistd.h> 43 #include <sys/stat.h> 44 #include <signal.h> 45 #include <procfs.h> 46 47 /* For POSIX-compliant getpwuid_r on Solaris */ 48 #define _POSIX_PTHREAD_SEMANTICS 49 #include <pwd.h> 50 51 static char* backing_store_file_name = NULL; // name of the backing store 52 // file, if successfully created. 53 54 // Standard Memory Implementation Details 55 56 // create the PerfData memory region in standard memory. 57 // 58 static char* create_standard_memory(size_t size) { 59 60 // allocate an aligned chuck of memory 61 char* mapAddress = os::reserve_memory(size); 62 63 if (mapAddress == NULL) { 64 return NULL; 65 } 66 67 // commit memory 68 if (!os::commit_memory(mapAddress, size, !ExecMem)) { 69 if (PrintMiscellaneous && Verbose) { 70 warning("Could not commit PerfData memory\n"); 71 } 72 os::release_memory(mapAddress, size); 73 return NULL; 74 } 75 76 return mapAddress; 77 } 78 79 // delete the PerfData memory region 80 // 81 static void delete_standard_memory(char* addr, size_t size) { 82 83 // there are no persistent external resources to cleanup for standard 84 // memory. since DestroyJavaVM does not support unloading of the JVM, 85 // cleanup of the memory resource is not performed. The memory will be 86 // reclaimed by the OS upon termination of the process. 87 // 88 return; 89 } 90 91 // save the specified memory region to the given file 92 // 93 // Note: this function might be called from signal handler (by os::abort()), 94 // don't allocate heap memory. 95 // 96 static void save_memory_to_file(char* addr, size_t size) { 97 98 const char* destfile = PerfMemory::get_perfdata_file_path(); 99 assert(destfile[0] != '\0', "invalid PerfData file path"); 100 101 int result; 102 103 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), 104 result);; 105 if (result == OS_ERR) { 106 if (PrintMiscellaneous && Verbose) { 107 warning("Could not create Perfdata save file: %s: %s\n", 108 destfile, os::strerror(errno)); 109 } 110 } else { 111 112 int fd = result; 113 114 for (size_t remaining = size; remaining > 0;) { 115 116 RESTARTABLE(::write(fd, addr, remaining), result); 117 if (result == OS_ERR) { 118 if (PrintMiscellaneous && Verbose) { 119 warning("Could not write Perfdata save file: %s: %s\n", 120 destfile, os::strerror(errno)); 121 } 122 break; 123 } 124 remaining -= (size_t)result; 125 addr += result; 126 } 127 128 result = ::close(fd); 129 if (PrintMiscellaneous && Verbose) { 130 if (result == OS_ERR) { 131 warning("Could not close %s: %s\n", destfile, os::strerror(errno)); 132 } 133 } 134 } 135 FREE_C_HEAP_ARRAY(char, destfile); 136 } 137 138 139 // Shared Memory Implementation Details 140 141 // Note: the solaris and linux shared memory implementation uses the mmap 142 // interface with a backing store file to implement named shared memory. 143 // Using the file system as the name space for shared memory allows a 144 // common name space to be supported across a variety of platforms. It 145 // also provides a name space that Java applications can deal with through 146 // simple file apis. 147 // 148 // The solaris and linux implementations store the backing store file in 149 // a user specific temporary directory located in the /tmp file system, 150 // which is always a local file system and is sometimes a RAM based file 151 // system. 152 153 // return the user specific temporary directory name. 154 // 155 // the caller is expected to free the allocated memory. 156 // 157 static char* get_user_tmp_dir(const char* user) { 158 159 const char* tmpdir = os::get_temp_directory(); 160 const char* perfdir = PERFDATA_NAME; 161 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3; 162 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 163 164 // construct the path name to user specific tmp directory 165 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user); 166 167 return dirname; 168 } 169 170 // convert the given file name into a process id. if the file 171 // does not meet the file naming constraints, return 0. 172 // 173 static pid_t filename_to_pid(const char* filename) { 174 175 // a filename that doesn't begin with a digit is not a 176 // candidate for conversion. 177 // 178 if (!isdigit(*filename)) { 179 return 0; 180 } 181 182 // check if file name can be converted to an integer without 183 // any leftover characters. 184 // 185 char* remainder = NULL; 186 errno = 0; 187 pid_t pid = (pid_t)strtol(filename, &remainder, 10); 188 189 if (errno != 0) { 190 return 0; 191 } 192 193 // check for left over characters. If any, then the filename is 194 // not a candidate for conversion. 195 // 196 if (remainder != NULL && *remainder != '\0') { 197 return 0; 198 } 199 200 // successful conversion, return the pid 201 return pid; 202 } 203 204 205 // Check if the given statbuf is considered a secure directory for 206 // the backing store files. Returns true if the directory is considered 207 // a secure location. Returns false if the statbuf is a symbolic link or 208 // if an error occurred. 209 // 210 static bool is_statbuf_secure(struct stat *statp) { 211 if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) { 212 // The path represents a link or some non-directory file type, 213 // which is not what we expected. Declare it insecure. 214 // 215 return false; 216 } 217 // We have an existing directory, check if the permissions are safe. 218 // 219 if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) { 220 // The directory is open for writing and could be subjected 221 // to a symlink or a hard link attack. Declare it insecure. 222 // 223 return false; 224 } 225 // If user is not root then see if the uid of the directory matches the effective uid of the process. 226 uid_t euid = geteuid(); 227 if ((euid != 0) && (statp->st_uid != euid)) { 228 // The directory was not created by this user, declare it insecure. 229 // 230 return false; 231 } 232 return true; 233 } 234 235 236 // Check if the given path is considered a secure directory for 237 // the backing store files. Returns true if the directory exists 238 // and is considered a secure location. Returns false if the path 239 // is a symbolic link or if an error occurred. 240 // 241 static bool is_directory_secure(const char* path) { 242 struct stat statbuf; 243 int result = 0; 244 245 RESTARTABLE(::lstat(path, &statbuf), result); 246 if (result == OS_ERR) { 247 return false; 248 } 249 250 // The path exists, see if it is secure. 251 return is_statbuf_secure(&statbuf); 252 } 253 254 255 // Check if the given directory file descriptor is considered a secure 256 // directory for the backing store files. Returns true if the directory 257 // exists and is considered a secure location. Returns false if the path 258 // is a symbolic link or if an error occurred. 259 // 260 static bool is_dirfd_secure(int dir_fd) { 261 struct stat statbuf; 262 int result = 0; 263 264 RESTARTABLE(::fstat(dir_fd, &statbuf), result); 265 if (result == OS_ERR) { 266 return false; 267 } 268 269 // The path exists, now check its mode. 270 return is_statbuf_secure(&statbuf); 271 } 272 273 274 // Check to make sure fd1 and fd2 are referencing the same file system object. 275 // 276 static bool is_same_fsobject(int fd1, int fd2) { 277 struct stat statbuf1; 278 struct stat statbuf2; 279 int result = 0; 280 281 RESTARTABLE(::fstat(fd1, &statbuf1), result); 282 if (result == OS_ERR) { 283 return false; 284 } 285 RESTARTABLE(::fstat(fd2, &statbuf2), result); 286 if (result == OS_ERR) { 287 return false; 288 } 289 290 if ((statbuf1.st_ino == statbuf2.st_ino) && 291 (statbuf1.st_dev == statbuf2.st_dev)) { 292 return true; 293 } else { 294 return false; 295 } 296 } 297 298 299 // Open the directory of the given path and validate it. 300 // Return a DIR * of the open directory. 301 // 302 static DIR *open_directory_secure(const char* dirname) { 303 // Open the directory using open() so that it can be verified 304 // to be secure by calling is_dirfd_secure(), opendir() and then check 305 // to see if they are the same file system object. This method does not 306 // introduce a window of opportunity for the directory to be attacked that 307 // calling opendir() and is_directory_secure() does. 308 int result; 309 DIR *dirp = NULL; 310 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result); 311 if (result == OS_ERR) { 312 // Directory doesn't exist or is a symlink, so there is nothing to cleanup. 313 if (PrintMiscellaneous && Verbose) { 314 if (errno == ELOOP) { 315 warning("directory %s is a symlink and is not secure\n", dirname); 316 } else { 317 warning("could not open directory %s: %s\n", dirname, os::strerror(errno)); 318 } 319 } 320 return dirp; 321 } 322 int fd = result; 323 324 // Determine if the open directory is secure. 325 if (!is_dirfd_secure(fd)) { 326 // The directory is not a secure directory. 327 os::close(fd); 328 return dirp; 329 } 330 331 // Open the directory. 332 dirp = ::opendir(dirname); 333 if (dirp == NULL) { 334 // The directory doesn't exist, close fd and return. 335 os::close(fd); 336 return dirp; 337 } 338 339 // Check to make sure fd and dirp are referencing the same file system object. 340 if (!is_same_fsobject(fd, dirp->d_fd)) { 341 // The directory is not secure. 342 os::close(fd); 343 os::closedir(dirp); 344 dirp = NULL; 345 return dirp; 346 } 347 348 // Close initial open now that we know directory is secure 349 os::close(fd); 350 351 return dirp; 352 } 353 354 // NOTE: The code below uses fchdir(), open() and unlink() because 355 // fdopendir(), openat() and unlinkat() are not supported on all 356 // versions. Once the support for fdopendir(), openat() and unlinkat() 357 // is available on all supported versions the code can be changed 358 // to use these functions. 359 360 // Open the directory of the given path, validate it and set the 361 // current working directory to it. 362 // Return a DIR * of the open directory and the saved cwd fd. 363 // 364 static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) { 365 366 // Open the directory. 367 DIR* dirp = open_directory_secure(dirname); 368 if (dirp == NULL) { 369 // Directory doesn't exist or is insecure, so there is nothing to cleanup. 370 return dirp; 371 } 372 int fd = dirp->d_fd; 373 374 // Open a fd to the cwd and save it off. 375 int result; 376 RESTARTABLE(::open(".", O_RDONLY), result); 377 if (result == OS_ERR) { 378 *saved_cwd_fd = -1; 379 } else { 380 *saved_cwd_fd = result; 381 } 382 383 // Set the current directory to dirname by using the fd of the directory and 384 // handle errors, otherwise shared memory files will be created in cwd. 385 result = fchdir(fd); 386 if (result == OS_ERR) { 387 if (PrintMiscellaneous && Verbose) { 388 warning("could not change to directory %s", dirname); 389 } 390 if (*saved_cwd_fd != -1) { 391 ::close(*saved_cwd_fd); 392 *saved_cwd_fd = -1; 393 } 394 // Close the directory. 395 os::closedir(dirp); 396 return NULL; 397 } else { 398 return dirp; 399 } 400 } 401 402 // Close the directory and restore the current working directory. 403 // 404 static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) { 405 406 int result; 407 // If we have a saved cwd change back to it and close the fd. 408 if (saved_cwd_fd != -1) { 409 result = fchdir(saved_cwd_fd); 410 ::close(saved_cwd_fd); 411 } 412 413 // Close the directory. 414 os::closedir(dirp); 415 } 416 417 // Check if the given file descriptor is considered a secure. 418 // 419 static bool is_file_secure(int fd, const char *filename) { 420 421 int result; 422 struct stat statbuf; 423 424 // Determine if the file is secure. 425 RESTARTABLE(::fstat(fd, &statbuf), result); 426 if (result == OS_ERR) { 427 if (PrintMiscellaneous && Verbose) { 428 warning("fstat failed on %s: %s\n", filename, os::strerror(errno)); 429 } 430 return false; 431 } 432 if (statbuf.st_nlink > 1) { 433 // A file with multiple links is not expected. 434 if (PrintMiscellaneous && Verbose) { 435 warning("file %s has multiple links\n", filename); 436 } 437 return false; 438 } 439 return true; 440 } 441 442 // return the user name for the given user id 443 // 444 // the caller is expected to free the allocated memory. 445 // 446 static char* get_user_name(uid_t uid) { 447 448 struct passwd pwent; 449 450 // determine the max pwbuf size from sysconf, and hardcode 451 // a default if this not available through sysconf. 452 // 453 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); 454 if (bufsize == -1) 455 bufsize = 1024; 456 457 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 458 459 struct passwd* p = NULL; 460 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 461 462 if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 463 if (PrintMiscellaneous && Verbose) { 464 if (p == NULL) { 465 warning("Could not retrieve passwd entry: %s\n", 466 os::strerror(errno)); 467 } 468 else { 469 warning("Could not determine user name: %s\n", 470 p->pw_name == NULL ? "pw_name = NULL" : 471 "pw_name zero length"); 472 } 473 } 474 FREE_C_HEAP_ARRAY(char, pwbuf); 475 return NULL; 476 } 477 478 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal); 479 strcpy(user_name, p->pw_name); 480 481 FREE_C_HEAP_ARRAY(char, pwbuf); 482 return user_name; 483 } 484 485 // return the name of the user that owns the process identified by vmid. 486 // 487 // This method uses a slow directory search algorithm to find the backing 488 // store file for the specified vmid and returns the user name, as determined 489 // by the user name suffix of the hsperfdata_<username> directory name. 490 // 491 // the caller is expected to free the allocated memory. 492 // 493 static char* get_user_name_slow(int vmid, TRAPS) { 494 495 // short circuit the directory search if the process doesn't even exist. 496 if (kill(vmid, 0) == OS_ERR) { 497 if (errno == ESRCH) { 498 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 499 "Process not found"); 500 } 501 else /* EPERM */ { 502 THROW_MSG_0(vmSymbols::java_io_IOException(), os::strerror(errno)); 503 } 504 } 505 506 // directory search 507 char* oldest_user = NULL; 508 time_t oldest_ctime = 0; 509 510 const char* tmpdirname = os::get_temp_directory(); 511 512 // open the temp directory 513 DIR* tmpdirp = os::opendir(tmpdirname); 514 515 if (tmpdirp == NULL) { 516 // Cannot open the directory to get the user name, return. 517 return NULL; 518 } 519 520 // for each entry in the directory that matches the pattern hsperfdata_*, 521 // open the directory and check if the file for the given vmid exists. 522 // The file with the expected name and the latest creation date is used 523 // to determine the user name for the process id. 524 // 525 struct dirent* dentry; 526 errno = 0; 527 while ((dentry = os::readdir(tmpdirp)) != NULL) { 528 529 // check if the directory entry is a hsperfdata file 530 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { 531 continue; 532 } 533 534 char* usrdir_name = NEW_C_HEAP_ARRAY(char, 535 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal); 536 strcpy(usrdir_name, tmpdirname); 537 strcat(usrdir_name, "/"); 538 strcat(usrdir_name, dentry->d_name); 539 540 // open the user directory 541 DIR* subdirp = open_directory_secure(usrdir_name); 542 543 if (subdirp == NULL) { 544 FREE_C_HEAP_ARRAY(char, usrdir_name); 545 continue; 546 } 547 548 // Since we don't create the backing store files in directories 549 // pointed to by symbolic links, we also don't follow them when 550 // looking for the files. We check for a symbolic link after the 551 // call to opendir in order to eliminate a small window where the 552 // symlink can be exploited. 553 // 554 if (!is_directory_secure(usrdir_name)) { 555 FREE_C_HEAP_ARRAY(char, usrdir_name); 556 os::closedir(subdirp); 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 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) { 616 617 char psinfo_name[PATH_MAX]; 618 int result; 619 620 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid); 621 622 RESTARTABLE(::open(psinfo_name, O_RDONLY), result); 623 624 if (result != OS_ERR) { 625 int fd = result; 626 627 psinfo_t psinfo; 628 char* addr = (char*)&psinfo; 629 630 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) { 631 632 RESTARTABLE(::read(fd, addr, remaining), result); 633 if (result == OS_ERR) { 634 ::close(fd); 635 THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error"); 636 } else { 637 remaining-=result; 638 addr+=result; 639 } 640 } 641 642 ::close(fd); 643 644 // get the user name for the effective user id of the process 645 char* user_name = get_user_name(psinfo.pr_euid); 646 647 return user_name; 648 } 649 650 if (result == OS_ERR && errno == EACCES) { 651 652 // In this case, the psinfo file for the process id existed, 653 // but we didn't have permission to access it. 654 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 655 os::strerror(errno)); 656 } 657 658 // at this point, we don't know if the process id itself doesn't 659 // exist or if the psinfo file doesn't exit. If the psinfo file 660 // doesn't exist, then we are running on Solaris 2.5.1 or earlier. 661 // since the structured procfs and old procfs interfaces can't be 662 // mixed, we attempt to find the file through a directory search. 663 664 return get_user_name_slow(vmid, THREAD); 665 } 666 667 // return the file name of the backing store file for the named 668 // shared memory region for the given user name and vmid. 669 // 670 // the caller is expected to free the allocated memory. 671 // 672 static char* get_sharedmem_filename(const char* dirname, int vmid) { 673 674 // add 2 for the file separator and a NULL terminator. 675 size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 676 677 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 678 snprintf(name, nbytes, "%s/%d", dirname, vmid); 679 680 return name; 681 } 682 683 684 // remove file 685 // 686 // this method removes the file specified by the given path 687 // 688 static void remove_file(const char* path) { 689 690 int result; 691 692 // if the file is a directory, the following unlink will fail. since 693 // we don't expect to find directories in the user temp directory, we 694 // won't try to handle this situation. even if accidentially or 695 // maliciously planted, the directory's presence won't hurt anything. 696 // 697 RESTARTABLE(::unlink(path), result); 698 if (PrintMiscellaneous && Verbose && result == OS_ERR) { 699 if (errno != ENOENT) { 700 warning("Could not unlink shared memory backing" 701 " store file %s : %s\n", path, os::strerror(errno)); 702 } 703 } 704 } 705 706 707 // cleanup stale shared memory resources 708 // 709 // This method attempts to remove all stale shared memory files in 710 // the named user temporary directory. It scans the named directory 711 // for files matching the pattern ^$[0-9]*$. For each file found, the 712 // process id is extracted from the file name and a test is run to 713 // determine if the process is alive. If the process is not alive, 714 // any stale file resources are removed. 715 // 716 static void cleanup_sharedmem_resources(const char* dirname) { 717 718 int saved_cwd_fd; 719 // open the directory 720 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 721 if (dirp == NULL) { 722 // directory doesn't exist or is insecure, so there is nothing to cleanup 723 return; 724 } 725 726 // for each entry in the directory that matches the expected file 727 // name pattern, determine if the file resources are stale and if 728 // so, remove the file resources. Note, instrumented HotSpot processes 729 // for this user may start and/or terminate during this search and 730 // remove or create new files in this directory. The behavior of this 731 // loop under these conditions is dependent upon the implementation of 732 // opendir/readdir. 733 // 734 struct dirent* entry; 735 errno = 0; 736 while ((entry = os::readdir(dirp)) != NULL) { 737 738 pid_t pid = filename_to_pid(entry->d_name); 739 740 if (pid == 0) { 741 742 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 743 744 // attempt to remove all unexpected files, except "." and ".." 745 unlink(entry->d_name); 746 } 747 748 errno = 0; 749 continue; 750 } 751 752 // we now have a file name that converts to a valid integer 753 // that could represent a process id . if this process id 754 // matches the current process id or the process is not running, 755 // then remove the stale file resources. 756 // 757 // process liveness is detected by sending signal number 0 to 758 // the process id (see kill(2)). if kill determines that the 759 // process does not exist, then the file resources are removed. 760 // if kill determines that that we don't have permission to 761 // signal the process, then the file resources are assumed to 762 // be stale and are removed because the resources for such a 763 // process should be in a different user specific directory. 764 // 765 if ((pid == os::current_process_id()) || 766 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 767 768 unlink(entry->d_name); 769 } 770 errno = 0; 771 } 772 773 // close the directory and reset the current working directory 774 close_directory_secure_cwd(dirp, saved_cwd_fd); 775 } 776 777 // make the user specific temporary directory. Returns true if 778 // the directory exists and is secure upon return. Returns false 779 // if the directory exists but is either a symlink, is otherwise 780 // insecure, or if an error occurred. 781 // 782 static bool make_user_tmp_dir(const char* dirname) { 783 784 // create the directory with 0755 permissions. note that the directory 785 // will be owned by euid::egid, which may not be the same as uid::gid. 786 // 787 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 788 if (errno == EEXIST) { 789 // The directory already exists and was probably created by another 790 // JVM instance. However, this could also be the result of a 791 // deliberate symlink. Verify that the existing directory is safe. 792 // 793 if (!is_directory_secure(dirname)) { 794 // directory is not secure 795 if (PrintMiscellaneous && Verbose) { 796 warning("%s directory is insecure\n", dirname); 797 } 798 return false; 799 } 800 } 801 else { 802 // we encountered some other failure while attempting 803 // to create the directory 804 // 805 if (PrintMiscellaneous && Verbose) { 806 warning("could not create directory %s: %s\n", 807 dirname, os::strerror(errno)); 808 } 809 return false; 810 } 811 } 812 return true; 813 } 814 815 // create the shared memory file resources 816 // 817 // This method creates the shared memory file with the given size 818 // This method also creates the user specific temporary directory, if 819 // it does not yet exist. 820 // 821 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 822 823 // make the user temporary directory 824 if (!make_user_tmp_dir(dirname)) { 825 // could not make/find the directory or the found directory 826 // was not secure 827 return -1; 828 } 829 830 int saved_cwd_fd; 831 // open the directory and set the current working directory to it 832 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 833 if (dirp == NULL) { 834 // Directory doesn't exist or is insecure, so cannot create shared 835 // memory file. 836 return -1; 837 } 838 839 // Open the filename in the current directory. 840 // Cannot use O_TRUNC here; truncation of an existing file has to happen 841 // after the is_file_secure() check below. 842 int result; 843 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result); 844 if (result == OS_ERR) { 845 if (PrintMiscellaneous && Verbose) { 846 if (errno == ELOOP) { 847 warning("file %s is a symlink and is not secure\n", filename); 848 } else { 849 warning("could not create file %s: %s\n", filename, os::strerror(errno)); 850 } 851 } 852 // close the directory and reset the current working directory 853 close_directory_secure_cwd(dirp, saved_cwd_fd); 854 855 return -1; 856 } 857 // close the directory and reset the current working directory 858 close_directory_secure_cwd(dirp, saved_cwd_fd); 859 860 // save the file descriptor 861 int fd = result; 862 863 // check to see if the file is secure 864 if (!is_file_secure(fd, filename)) { 865 ::close(fd); 866 return -1; 867 } 868 869 // truncate the file to get rid of any existing data 870 RESTARTABLE(::ftruncate(fd, (off_t)0), result); 871 if (result == OS_ERR) { 872 if (PrintMiscellaneous && Verbose) { 873 warning("could not truncate shared memory file: %s\n", os::strerror(errno)); 874 } 875 ::close(fd); 876 return -1; 877 } 878 // set the file size 879 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 880 if (result == OS_ERR) { 881 if (PrintMiscellaneous && Verbose) { 882 warning("could not set shared memory file size: %s\n", os::strerror(errno)); 883 } 884 ::close(fd); 885 return -1; 886 } 887 888 return fd; 889 } 890 891 // open the shared memory file for the given user and vmid. returns 892 // the file descriptor for the open file or -1 if the file could not 893 // be opened. 894 // 895 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 896 897 // open the file 898 int result; 899 RESTARTABLE(::open(filename, oflags), result); 900 if (result == OS_ERR) { 901 if (errno == ENOENT) { 902 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 903 "Process not found", OS_ERR); 904 } 905 else if (errno == EACCES) { 906 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 907 "Permission denied", OS_ERR); 908 } 909 else { 910 THROW_MSG_(vmSymbols::java_io_IOException(), 911 os::strerror(errno), OS_ERR); 912 } 913 } 914 int fd = result; 915 916 // check to see if the file is secure 917 if (!is_file_secure(fd, filename)) { 918 ::close(fd); 919 return -1; 920 } 921 922 return fd; 923 } 924 925 // create a named shared memory region. returns the address of the 926 // memory region on success or NULL on failure. A return value of 927 // NULL will ultimately disable the shared memory feature. 928 // 929 // On Solaris, the name space for shared memory objects 930 // is the file system name space. 931 // 932 // A monitoring application attaching to a JVM does not need to know 933 // the file system name of the shared memory object. However, it may 934 // be convenient for applications to discover the existence of newly 935 // created and terminating JVMs by watching the file system name space 936 // for files being created or removed. 937 // 938 static char* mmap_create_shared(size_t size) { 939 940 int result; 941 int fd; 942 char* mapAddress; 943 944 int vmid = os::current_process_id(); 945 946 char* user_name = get_user_name(geteuid()); 947 948 if (user_name == NULL) 949 return NULL; 950 951 char* dirname = get_user_tmp_dir(user_name); 952 char* filename = get_sharedmem_filename(dirname, vmid); 953 954 // get the short filename 955 char* short_filename = strrchr(filename, '/'); 956 if (short_filename == NULL) { 957 short_filename = filename; 958 } else { 959 short_filename++; 960 } 961 962 // cleanup any stale shared memory files 963 cleanup_sharedmem_resources(dirname); 964 965 assert(((size > 0) && (size % os::vm_page_size() == 0)), 966 "unexpected PerfMemory region size"); 967 968 fd = create_sharedmem_resources(dirname, short_filename, size); 969 970 FREE_C_HEAP_ARRAY(char, user_name); 971 FREE_C_HEAP_ARRAY(char, dirname); 972 973 if (fd == -1) { 974 FREE_C_HEAP_ARRAY(char, filename); 975 return NULL; 976 } 977 978 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 979 980 result = ::close(fd); 981 assert(result != OS_ERR, "could not close file"); 982 983 if (mapAddress == MAP_FAILED) { 984 if (PrintMiscellaneous && Verbose) { 985 warning("mmap failed - %s\n", os::strerror(errno)); 986 } 987 remove_file(filename); 988 FREE_C_HEAP_ARRAY(char, filename); 989 return NULL; 990 } 991 992 // save the file name for use in delete_shared_memory() 993 backing_store_file_name = filename; 994 995 // clear the shared memory region 996 (void)::memset((void*) mapAddress, 0, size); 997 998 // it does not go through os api, the operation has to record from here 999 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, 1000 size, CURRENT_PC, mtInternal); 1001 1002 return mapAddress; 1003 } 1004 1005 // release a named shared memory region 1006 // 1007 static void unmap_shared(char* addr, size_t bytes) { 1008 os::release_memory(addr, bytes); 1009 } 1010 1011 // create the PerfData memory region in shared memory. 1012 // 1013 static char* create_shared_memory(size_t size) { 1014 1015 // create the shared memory region. 1016 return mmap_create_shared(size); 1017 } 1018 1019 // delete the shared PerfData memory region 1020 // 1021 static void delete_shared_memory(char* addr, size_t size) { 1022 1023 // cleanup the persistent shared memory resources. since DestroyJavaVM does 1024 // not support unloading of the JVM, unmapping of the memory resource is 1025 // not performed. The memory will be reclaimed by the OS upon termination of 1026 // the process. The backing store file is deleted from the file system. 1027 1028 assert(!PerfDisableSharedMem, "shouldn't be here"); 1029 1030 if (backing_store_file_name != NULL) { 1031 remove_file(backing_store_file_name); 1032 // Don't.. Free heap memory could deadlock os::abort() if it is called 1033 // from signal handler. OS will reclaim the heap memory. 1034 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 1035 backing_store_file_name = NULL; 1036 } 1037 } 1038 1039 // return the size of the file for the given file descriptor 1040 // or 0 if it is not a valid size for a shared memory file 1041 // 1042 static size_t sharedmem_filesize(int fd, TRAPS) { 1043 1044 struct stat statbuf; 1045 int result; 1046 1047 RESTARTABLE(::fstat(fd, &statbuf), result); 1048 if (result == OS_ERR) { 1049 if (PrintMiscellaneous && Verbose) { 1050 warning("fstat failed: %s\n", os::strerror(errno)); 1051 } 1052 THROW_MSG_0(vmSymbols::java_io_IOException(), 1053 "Could not determine PerfMemory size"); 1054 } 1055 1056 if ((statbuf.st_size == 0) || 1057 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 1058 THROW_MSG_0(vmSymbols::java_io_IOException(), 1059 "Invalid PerfMemory size"); 1060 } 1061 1062 return (size_t)statbuf.st_size; 1063 } 1064 1065 // attach to a named shared memory region. 1066 // 1067 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 1068 1069 char* mapAddress; 1070 int result; 1071 int fd; 1072 size_t size = 0; 1073 const char* luser = NULL; 1074 1075 int mmap_prot; 1076 int file_flags; 1077 1078 ResourceMark rm; 1079 1080 // map the high level access mode to the appropriate permission 1081 // constructs for the file and the shared memory mapping. 1082 if (mode == PerfMemory::PERF_MODE_RO) { 1083 mmap_prot = PROT_READ; 1084 file_flags = O_RDONLY | O_NOFOLLOW; 1085 } 1086 else if (mode == PerfMemory::PERF_MODE_RW) { 1087 #ifdef LATER 1088 mmap_prot = PROT_READ | PROT_WRITE; 1089 file_flags = O_RDWR | O_NOFOLLOW; 1090 #else 1091 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1092 "Unsupported access mode"); 1093 #endif 1094 } 1095 else { 1096 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1097 "Illegal access mode"); 1098 } 1099 1100 if (user == NULL || strlen(user) == 0) { 1101 luser = get_user_name(vmid, CHECK); 1102 } 1103 else { 1104 luser = user; 1105 } 1106 1107 if (luser == NULL) { 1108 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1109 "Could not map vmid to user Name"); 1110 } 1111 1112 char* dirname = get_user_tmp_dir(luser); 1113 1114 // since we don't follow symbolic links when creating the backing 1115 // store file, we don't follow them when attaching either. 1116 // 1117 if (!is_directory_secure(dirname)) { 1118 FREE_C_HEAP_ARRAY(char, dirname); 1119 if (luser != user) { 1120 FREE_C_HEAP_ARRAY(char, luser); 1121 } 1122 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1123 "Process not found"); 1124 } 1125 1126 char* filename = get_sharedmem_filename(dirname, vmid); 1127 1128 // copy heap memory to resource memory. the open_sharedmem_file 1129 // method below need to use the filename, but could throw an 1130 // exception. using a resource array prevents the leak that 1131 // would otherwise occur. 1132 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); 1133 strcpy(rfilename, filename); 1134 1135 // free the c heap resources that are no longer needed 1136 if (luser != user) FREE_C_HEAP_ARRAY(char, luser); 1137 FREE_C_HEAP_ARRAY(char, dirname); 1138 FREE_C_HEAP_ARRAY(char, filename); 1139 1140 // open the shared memory file for the give vmid 1141 fd = open_sharedmem_file(rfilename, file_flags, THREAD); 1142 1143 if (fd == OS_ERR) { 1144 return; 1145 } 1146 1147 if (HAS_PENDING_EXCEPTION) { 1148 ::close(fd); 1149 return; 1150 } 1151 1152 if (*sizep == 0) { 1153 size = sharedmem_filesize(fd, CHECK); 1154 } else { 1155 size = *sizep; 1156 } 1157 1158 assert(size > 0, "unexpected size <= 0"); 1159 1160 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 1161 1162 result = ::close(fd); 1163 assert(result != OS_ERR, "could not close file"); 1164 1165 if (mapAddress == MAP_FAILED) { 1166 if (PrintMiscellaneous && Verbose) { 1167 warning("mmap failed: %s\n", os::strerror(errno)); 1168 } 1169 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 1170 "Could not map PerfMemory"); 1171 } 1172 1173 // it does not go through os api, the operation has to record from here 1174 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, 1175 size, CURRENT_PC, mtInternal); 1176 1177 *addr = mapAddress; 1178 *sizep = size; 1179 1180 log_debug(perf, memops)("mapped " SIZE_FORMAT " bytes for vmid %d at " 1181 INTPTR_FORMAT, size, vmid, (void*)mapAddress); 1182 } 1183 1184 // create the PerfData memory region 1185 // 1186 // This method creates the memory region used to store performance 1187 // data for the JVM. The memory may be created in standard or 1188 // shared memory. 1189 // 1190 void PerfMemory::create_memory_region(size_t size) { 1191 1192 if (PerfDisableSharedMem) { 1193 // do not share the memory for the performance data. 1194 _start = create_standard_memory(size); 1195 } 1196 else { 1197 _start = create_shared_memory(size); 1198 if (_start == NULL) { 1199 1200 // creation of the shared memory region failed, attempt 1201 // to create a contiguous, non-shared memory region instead. 1202 // 1203 if (PrintMiscellaneous && Verbose) { 1204 warning("Reverting to non-shared PerfMemory region.\n"); 1205 } 1206 PerfDisableSharedMem = true; 1207 _start = create_standard_memory(size); 1208 } 1209 } 1210 1211 if (_start != NULL) _capacity = size; 1212 1213 } 1214 1215 // delete the PerfData memory region 1216 // 1217 // This method deletes the memory region used to store performance 1218 // data for the JVM. The memory region indicated by the <address, size> 1219 // tuple will be inaccessible after a call to this method. 1220 // 1221 void PerfMemory::delete_memory_region() { 1222 1223 assert((start() != NULL && capacity() > 0), "verify proper state"); 1224 1225 // If user specifies PerfDataSaveFile, it will save the performance data 1226 // to the specified file name no matter whether PerfDataSaveToFile is specified 1227 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 1228 // -XX:+PerfDataSaveToFile. 1229 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 1230 save_memory_to_file(start(), capacity()); 1231 } 1232 1233 if (PerfDisableSharedMem) { 1234 delete_standard_memory(start(), capacity()); 1235 } 1236 else { 1237 delete_shared_memory(start(), capacity()); 1238 } 1239 } 1240 1241 // attach to the PerfData memory region for another JVM 1242 // 1243 // This method returns an <address, size> tuple that points to 1244 // a memory buffer that is kept reasonably synchronized with 1245 // the PerfData memory region for the indicated JVM. This 1246 // buffer may be kept in synchronization via shared memory 1247 // or some other mechanism that keeps the buffer updated. 1248 // 1249 // If the JVM chooses not to support the attachability feature, 1250 // this method should throw an UnsupportedOperation exception. 1251 // 1252 // This implementation utilizes named shared memory to map 1253 // the indicated process's PerfData memory region into this JVMs 1254 // address space. 1255 // 1256 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1257 1258 if (vmid == 0 || vmid == os::current_process_id()) { 1259 *addrp = start(); 1260 *sizep = capacity(); 1261 return; 1262 } 1263 1264 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1265 } 1266 1267 // detach from the PerfData memory region of another JVM 1268 // 1269 // This method detaches the PerfData memory region of another 1270 // JVM, specified as an <address, size> tuple of a buffer 1271 // in this process's address space. This method may perform 1272 // arbitrary actions to accomplish the detachment. The memory 1273 // region specified by <address, size> will be inaccessible after 1274 // a call to this method. 1275 // 1276 // If the JVM chooses not to support the attachability feature, 1277 // this method should throw an UnsupportedOperation exception. 1278 // 1279 // This implementation utilizes named shared memory to detach 1280 // the indicated process's PerfData memory region from this 1281 // process's address space. 1282 // 1283 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1284 1285 assert(addr != 0, "address sanity check"); 1286 assert(bytes > 0, "capacity sanity check"); 1287 1288 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1289 // prevent accidental detachment of this process's PerfMemory region 1290 return; 1291 } 1292 1293 unmap_shared(addr, bytes); 1294 }