1 /* 2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/vmSymbols.hpp" 27 #include "memory/allocation.inline.hpp" 28 #include "memory/resourceArea.hpp" 29 #include "oops/oop.inline.hpp" 30 #include "os_solaris.inline.hpp" 31 #include "runtime/handles.inline.hpp" 32 #include "runtime/perfMemory.hpp" 33 #include "services/memTracker.hpp" 34 #include "utilities/exceptions.hpp" 35 36 // put OS-includes here 37 #include <sys/types.h> 38 #include <sys/mman.h> 39 #include <errno.h> 40 #include <stdio.h> 41 #include <unistd.h> 42 #include <sys/stat.h> 43 #include <signal.h> 44 #include <procfs.h> 45 46 /* For POSIX-compliant getpwuid_r on Solaris */ 47 #define _POSIX_PTHREAD_SEMANTICS 48 #include <pwd.h> 49 50 static char* backing_store_file_name = NULL; // name of the backing store 51 // file, if successfully created. 52 53 // Standard Memory Implementation Details 54 55 // create the PerfData memory region in standard memory. 56 // 57 static char* create_standard_memory(size_t size) { 58 59 // allocate an aligned chuck of memory 60 char* mapAddress = os::reserve_memory(size); 61 62 if (mapAddress == NULL) { 63 return NULL; 64 } 65 66 // commit memory 67 if (!os::commit_memory(mapAddress, size, !ExecMem)) { 68 if (PrintMiscellaneous && Verbose) { 69 warning("Could not commit PerfData memory\n"); 70 } 71 os::release_memory(mapAddress, size); 72 return NULL; 73 } 74 75 return mapAddress; 76 } 77 78 // delete the PerfData memory region 79 // 80 static void delete_standard_memory(char* addr, size_t size) { 81 82 // there are no persistent external resources to cleanup for standard 83 // memory. since DestroyJavaVM does not support unloading of the JVM, 84 // cleanup of the memory resource is not performed. The memory will be 85 // reclaimed by the OS upon termination of the process. 86 // 87 return; 88 } 89 90 // save the specified memory region to the given file 91 // 92 // Note: this function might be called from signal handler (by os::abort()), 93 // don't allocate heap memory. 94 // 95 static void save_memory_to_file(char* addr, size_t size) { 96 97 const char* destfile = PerfMemory::get_perfdata_file_path(); 98 assert(destfile[0] != '\0', "invalid PerfData file path"); 99 100 int result; 101 102 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), 103 result);; 104 if (result == OS_ERR) { 105 if (PrintMiscellaneous && Verbose) { 106 warning("Could not create Perfdata save file: %s: %s\n", 107 destfile, os::strerror(errno)); 108 } 109 } else { 110 111 int fd = result; 112 113 for (size_t remaining = size; remaining > 0;) { 114 115 RESTARTABLE(::write(fd, addr, remaining), result); 116 if (result == OS_ERR) { 117 if (PrintMiscellaneous && Verbose) { 118 warning("Could not write Perfdata save file: %s: %s\n", 119 destfile, os::strerror(errno)); 120 } 121 break; 122 } 123 remaining -= (size_t)result; 124 addr += result; 125 } 126 127 result = ::close(fd); 128 if (PrintMiscellaneous && Verbose) { 129 if (result == OS_ERR) { 130 warning("Could not close %s: %s\n", destfile, os::strerror(errno)); 131 } 132 } 133 } 134 FREE_C_HEAP_ARRAY(char, destfile); 135 } 136 137 138 // Shared Memory Implementation Details 139 140 // Note: the solaris and linux shared memory implementation uses the mmap 141 // interface with a backing store file to implement named shared memory. 142 // Using the file system as the name space for shared memory allows a 143 // common name space to be supported across a variety of platforms. It 144 // also provides a name space that Java applications can deal with through 145 // simple file apis. 146 // 147 // The solaris and linux implementations store the backing store file in 148 // a user specific temporary directory located in the /tmp file system, 149 // which is always a local file system and is sometimes a RAM based file 150 // system. 151 152 // return the user specific temporary directory name. 153 // 154 // the caller is expected to free the allocated memory. 155 // 156 static char* get_user_tmp_dir(const char* user) { 157 158 const char* tmpdir = os::get_temp_directory(); 159 const char* perfdir = PERFDATA_NAME; 160 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3; 161 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 162 163 // construct the path name to user specific tmp directory 164 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user); 165 166 return dirname; 167 } 168 169 // convert the given file name into a process id. if the file 170 // does not meet the file naming constraints, return 0. 171 // 172 static pid_t filename_to_pid(const char* filename) { 173 174 // a filename that doesn't begin with a digit is not a 175 // candidate for conversion. 176 // 177 if (!isdigit(*filename)) { 178 return 0; 179 } 180 181 // check if file name can be converted to an integer without 182 // any leftover characters. 183 // 184 char* remainder = NULL; 185 errno = 0; 186 pid_t pid = (pid_t)strtol(filename, &remainder, 10); 187 188 if (errno != 0) { 189 return 0; 190 } 191 192 // check for left over characters. If any, then the filename is 193 // not a candidate for conversion. 194 // 195 if (remainder != NULL && *remainder != '\0') { 196 return 0; 197 } 198 199 // successful conversion, return the pid 200 return pid; 201 } 202 203 204 // Check if the given statbuf is considered a secure directory for 205 // the backing store files. Returns true if the directory is considered 206 // a secure location. Returns false if the statbuf is a symbolic link or 207 // if an error occurred. 208 // 209 static bool is_statbuf_secure(struct stat *statp) { 210 if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) { 211 // The path represents a link or some non-directory file type, 212 // which is not what we expected. Declare it insecure. 213 // 214 return false; 215 } 216 // We have an existing directory, check if the permissions are safe. 217 // 218 if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) { 219 // The directory is open for writing and could be subjected 220 // to a symlink or a hard link attack. Declare it insecure. 221 // 222 return false; 223 } 224 // If user is not root then see if the uid of the directory matches the effective uid of the process. 225 uid_t euid = geteuid(); 226 if ((euid != 0) && (statp->st_uid != euid)) { 227 // The directory was not created by this user, declare it insecure. 228 // 229 return false; 230 } 231 return true; 232 } 233 234 235 // Check if the given path is considered a secure directory for 236 // the backing store files. Returns true if the directory exists 237 // and is considered a secure location. Returns false if the path 238 // is a symbolic link or if an error occurred. 239 // 240 static bool is_directory_secure(const char* path) { 241 struct stat statbuf; 242 int result = 0; 243 244 RESTARTABLE(::lstat(path, &statbuf), result); 245 if (result == OS_ERR) { 246 return false; 247 } 248 249 // The path exists, see if it is secure. 250 return is_statbuf_secure(&statbuf); 251 } 252 253 254 // Check if the given directory file descriptor is considered a secure 255 // directory for the backing store files. Returns true if the directory 256 // exists and is considered a secure location. Returns false if the path 257 // is a symbolic link or if an error occurred. 258 // 259 static bool is_dirfd_secure(int dir_fd) { 260 struct stat statbuf; 261 int result = 0; 262 263 RESTARTABLE(::fstat(dir_fd, &statbuf), result); 264 if (result == OS_ERR) { 265 return false; 266 } 267 268 // The path exists, now check its mode. 269 return is_statbuf_secure(&statbuf); 270 } 271 272 273 // Check to make sure fd1 and fd2 are referencing the same file system object. 274 // 275 static bool is_same_fsobject(int fd1, int fd2) { 276 struct stat statbuf1; 277 struct stat statbuf2; 278 int result = 0; 279 280 RESTARTABLE(::fstat(fd1, &statbuf1), result); 281 if (result == OS_ERR) { 282 return false; 283 } 284 RESTARTABLE(::fstat(fd2, &statbuf2), result); 285 if (result == OS_ERR) { 286 return false; 287 } 288 289 if ((statbuf1.st_ino == statbuf2.st_ino) && 290 (statbuf1.st_dev == statbuf2.st_dev)) { 291 return true; 292 } else { 293 return false; 294 } 295 } 296 297 298 // Open the directory of the given path and validate it. 299 // Return a DIR * of the open directory. 300 // 301 static DIR *open_directory_secure(const char* dirname) { 302 // Open the directory using open() so that it can be verified 303 // to be secure by calling is_dirfd_secure(), opendir() and then check 304 // to see if they are the same file system object. This method does not 305 // introduce a window of opportunity for the directory to be attacked that 306 // calling opendir() and is_directory_secure() does. 307 int result; 308 DIR *dirp = NULL; 309 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result); 310 if (result == OS_ERR) { 311 // Directory doesn't exist or is a symlink, so there is nothing to cleanup. 312 if (PrintMiscellaneous && Verbose) { 313 if (errno == ELOOP) { 314 warning("directory %s is a symlink and is not secure\n", dirname); 315 } else { 316 warning("could not open directory %s: %s\n", dirname, os::strerror(errno)); 317 } 318 } 319 return dirp; 320 } 321 int fd = result; 322 323 // Determine if the open directory is secure. 324 if (!is_dirfd_secure(fd)) { 325 // The directory is not a secure directory. 326 os::close(fd); 327 return dirp; 328 } 329 330 // Open the directory. 331 dirp = ::opendir(dirname); 332 if (dirp == NULL) { 333 // The directory doesn't exist, close fd and return. 334 os::close(fd); 335 return dirp; 336 } 337 338 // Check to make sure fd and dirp are referencing the same file system object. 339 if (!is_same_fsobject(fd, dirp->d_fd)) { 340 // The directory is not secure. 341 os::close(fd); 342 os::closedir(dirp); 343 dirp = NULL; 344 return dirp; 345 } 346 347 // Close initial open now that we know directory is secure 348 os::close(fd); 349 350 return dirp; 351 } 352 353 // NOTE: The code below uses fchdir(), open() and unlink() because 354 // fdopendir(), openat() and unlinkat() are not supported on all 355 // versions. Once the support for fdopendir(), openat() and unlinkat() 356 // is available on all supported versions the code can be changed 357 // to use these functions. 358 359 // Open the directory of the given path, validate it and set the 360 // current working directory to it. 361 // Return a DIR * of the open directory and the saved cwd fd. 362 // 363 static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) { 364 365 // Open the directory. 366 DIR* dirp = open_directory_secure(dirname); 367 if (dirp == NULL) { 368 // Directory doesn't exist or is insecure, so there is nothing to cleanup. 369 return dirp; 370 } 371 int fd = dirp->d_fd; 372 373 // Open a fd to the cwd and save it off. 374 int result; 375 RESTARTABLE(::open(".", O_RDONLY), result); 376 if (result == OS_ERR) { 377 *saved_cwd_fd = -1; 378 } else { 379 *saved_cwd_fd = result; 380 } 381 382 // Set the current directory to dirname by using the fd of the directory and 383 // handle errors, otherwise shared memory files will be created in cwd. 384 result = fchdir(fd); 385 if (result == OS_ERR) { 386 if (PrintMiscellaneous && Verbose) { 387 warning("could not change to directory %s", dirname); 388 } 389 if (*saved_cwd_fd != -1) { 390 ::close(*saved_cwd_fd); 391 *saved_cwd_fd = -1; 392 } 393 // Close the directory. 394 os::closedir(dirp); 395 return NULL; 396 } else { 397 return dirp; 398 } 399 } 400 401 // Close the directory and restore the current working directory. 402 // 403 static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) { 404 405 int result; 406 // If we have a saved cwd change back to it and close the fd. 407 if (saved_cwd_fd != -1) { 408 result = fchdir(saved_cwd_fd); 409 ::close(saved_cwd_fd); 410 } 411 412 // Close the directory. 413 os::closedir(dirp); 414 } 415 416 // Check if the given file descriptor is considered a secure. 417 // 418 static bool is_file_secure(int fd, const char *filename) { 419 420 int result; 421 struct stat statbuf; 422 423 // Determine if the file is secure. 424 RESTARTABLE(::fstat(fd, &statbuf), result); 425 if (result == OS_ERR) { 426 if (PrintMiscellaneous && Verbose) { 427 warning("fstat failed on %s: %s\n", filename, os::strerror(errno)); 428 } 429 return false; 430 } 431 if (statbuf.st_nlink > 1) { 432 // A file with multiple links is not expected. 433 if (PrintMiscellaneous && Verbose) { 434 warning("file %s has multiple links\n", filename); 435 } 436 return false; 437 } 438 return true; 439 } 440 441 // return the user name for the given user id 442 // 443 // the caller is expected to free the allocated memory. 444 // 445 static char* get_user_name(uid_t uid) { 446 447 struct passwd pwent; 448 449 // determine the max pwbuf size from sysconf, and hardcode 450 // a default if this not available through sysconf. 451 // 452 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); 453 if (bufsize == -1) 454 bufsize = 1024; 455 456 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); 457 458 struct passwd* p = NULL; 459 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); 460 461 if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { 462 if (PrintMiscellaneous && Verbose) { 463 if (p == NULL) { 464 warning("Could not retrieve passwd entry: %s\n", 465 os::strerror(errno)); 466 } 467 else { 468 warning("Could not determine user name: %s\n", 469 p->pw_name == NULL ? "pw_name = NULL" : 470 "pw_name zero length"); 471 } 472 } 473 FREE_C_HEAP_ARRAY(char, pwbuf); 474 return NULL; 475 } 476 477 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal); 478 strcpy(user_name, p->pw_name); 479 480 FREE_C_HEAP_ARRAY(char, pwbuf); 481 return user_name; 482 } 483 484 // return the name of the user that owns the process identified by vmid. 485 // 486 // This method uses a slow directory search algorithm to find the backing 487 // store file for the specified vmid and returns the user name, as determined 488 // by the user name suffix of the hsperfdata_<username> directory name. 489 // 490 // the caller is expected to free the allocated memory. 491 // 492 static char* get_user_name_slow(int vmid, TRAPS) { 493 494 // short circuit the directory search if the process doesn't even exist. 495 if (kill(vmid, 0) == OS_ERR) { 496 if (errno == ESRCH) { 497 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 498 "Process not found"); 499 } 500 else /* EPERM */ { 501 THROW_MSG_0(vmSymbols::java_io_IOException(), os::strerror(errno)); 502 } 503 } 504 505 // directory search 506 char* oldest_user = NULL; 507 time_t oldest_ctime = 0; 508 509 const char* tmpdirname = os::get_temp_directory(); 510 511 // open the temp directory 512 DIR* tmpdirp = os::opendir(tmpdirname); 513 514 if (tmpdirp == NULL) { 515 // Cannot open the directory to get the user name, return. 516 return NULL; 517 } 518 519 // for each entry in the directory that matches the pattern hsperfdata_*, 520 // open the directory and check if the file for the given vmid exists. 521 // The file with the expected name and the latest creation date is used 522 // to determine the user name for the process id. 523 // 524 struct dirent* dentry; 525 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal); 526 errno = 0; 527 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != 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 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal); 562 errno = 0; 563 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) { 564 565 if (filename_to_pid(udentry->d_name) == vmid) { 566 struct stat statbuf; 567 int result; 568 569 char* filename = NEW_C_HEAP_ARRAY(char, 570 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal); 571 572 strcpy(filename, usrdir_name); 573 strcat(filename, "/"); 574 strcat(filename, udentry->d_name); 575 576 // don't follow symbolic links for the file 577 RESTARTABLE(::lstat(filename, &statbuf), result); 578 if (result == OS_ERR) { 579 FREE_C_HEAP_ARRAY(char, filename); 580 continue; 581 } 582 583 // skip over files that are not regular files. 584 if (!S_ISREG(statbuf.st_mode)) { 585 FREE_C_HEAP_ARRAY(char, filename); 586 continue; 587 } 588 589 // compare and save filename with latest creation time 590 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { 591 592 if (statbuf.st_ctime > oldest_ctime) { 593 char* user = strchr(dentry->d_name, '_') + 1; 594 595 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user); 596 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal); 597 598 strcpy(oldest_user, user); 599 oldest_ctime = statbuf.st_ctime; 600 } 601 } 602 603 FREE_C_HEAP_ARRAY(char, filename); 604 } 605 } 606 os::closedir(subdirp); 607 FREE_C_HEAP_ARRAY(char, udbuf); 608 FREE_C_HEAP_ARRAY(char, usrdir_name); 609 } 610 os::closedir(tmpdirp); 611 FREE_C_HEAP_ARRAY(char, tdbuf); 612 613 return(oldest_user); 614 } 615 616 // return the name of the user that owns the JVM indicated by the given vmid. 617 // 618 static char* get_user_name(int vmid, TRAPS) { 619 620 char psinfo_name[PATH_MAX]; 621 int result; 622 623 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid); 624 625 RESTARTABLE(::open(psinfo_name, O_RDONLY), result); 626 627 if (result != OS_ERR) { 628 int fd = result; 629 630 psinfo_t psinfo; 631 char* addr = (char*)&psinfo; 632 633 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) { 634 635 RESTARTABLE(::read(fd, addr, remaining), result); 636 if (result == OS_ERR) { 637 ::close(fd); 638 THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error"); 639 } else { 640 remaining-=result; 641 addr+=result; 642 } 643 } 644 645 ::close(fd); 646 647 // get the user name for the effective user id of the process 648 char* user_name = get_user_name(psinfo.pr_euid); 649 650 return user_name; 651 } 652 653 if (result == OS_ERR && errno == EACCES) { 654 655 // In this case, the psinfo file for the process id existed, 656 // but we didn't have permission to access it. 657 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), 658 os::strerror(errno)); 659 } 660 661 // at this point, we don't know if the process id itself doesn't 662 // exist or if the psinfo file doesn't exit. If the psinfo file 663 // doesn't exist, then we are running on Solaris 2.5.1 or earlier. 664 // since the structured procfs and old procfs interfaces can't be 665 // mixed, we attempt to find the file through a directory search. 666 667 return get_user_name_slow(vmid, THREAD); 668 } 669 670 // return the file name of the backing store file for the named 671 // shared memory region for the given user name and vmid. 672 // 673 // the caller is expected to free the allocated memory. 674 // 675 static char* get_sharedmem_filename(const char* dirname, int vmid) { 676 677 // add 2 for the file separator and a NULL terminator. 678 size_t nbytes = strlen(dirname) + UINT_CHARS + 2; 679 680 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); 681 snprintf(name, nbytes, "%s/%d", dirname, vmid); 682 683 return name; 684 } 685 686 687 // remove file 688 // 689 // this method removes the file specified by the given path 690 // 691 static void remove_file(const char* path) { 692 693 int result; 694 695 // if the file is a directory, the following unlink will fail. since 696 // we don't expect to find directories in the user temp directory, we 697 // won't try to handle this situation. even if accidentially or 698 // maliciously planted, the directory's presence won't hurt anything. 699 // 700 RESTARTABLE(::unlink(path), result); 701 if (PrintMiscellaneous && Verbose && result == OS_ERR) { 702 if (errno != ENOENT) { 703 warning("Could not unlink shared memory backing" 704 " store file %s : %s\n", path, os::strerror(errno)); 705 } 706 } 707 } 708 709 710 // cleanup stale shared memory resources 711 // 712 // This method attempts to remove all stale shared memory files in 713 // the named user temporary directory. It scans the named directory 714 // for files matching the pattern ^$[0-9]*$. For each file found, the 715 // process id is extracted from the file name and a test is run to 716 // determine if the process is alive. If the process is not alive, 717 // any stale file resources are removed. 718 // 719 static void cleanup_sharedmem_resources(const char* dirname) { 720 721 int saved_cwd_fd; 722 // open the directory 723 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 724 if (dirp == NULL) { 725 // directory doesn't exist or is insecure, so there is nothing to cleanup 726 return; 727 } 728 729 // for each entry in the directory that matches the expected file 730 // name pattern, determine if the file resources are stale and if 731 // so, remove the file resources. Note, instrumented HotSpot processes 732 // for this user may start and/or terminate during this search and 733 // remove or create new files in this directory. The behavior of this 734 // loop under these conditions is dependent upon the implementation of 735 // opendir/readdir. 736 // 737 struct dirent* entry; 738 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal); 739 740 errno = 0; 741 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) { 742 743 pid_t pid = filename_to_pid(entry->d_name); 744 745 if (pid == 0) { 746 747 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { 748 749 // attempt to remove all unexpected files, except "." and ".." 750 unlink(entry->d_name); 751 } 752 753 errno = 0; 754 continue; 755 } 756 757 // we now have a file name that converts to a valid integer 758 // that could represent a process id . if this process id 759 // matches the current process id or the process is not running, 760 // then remove the stale file resources. 761 // 762 // process liveness is detected by sending signal number 0 to 763 // the process id (see kill(2)). if kill determines that the 764 // process does not exist, then the file resources are removed. 765 // if kill determines that that we don't have permission to 766 // signal the process, then the file resources are assumed to 767 // be stale and are removed because the resources for such a 768 // process should be in a different user specific directory. 769 // 770 if ((pid == os::current_process_id()) || 771 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { 772 773 unlink(entry->d_name); 774 } 775 errno = 0; 776 } 777 778 // close the directory and reset the current working directory 779 close_directory_secure_cwd(dirp, saved_cwd_fd); 780 781 FREE_C_HEAP_ARRAY(char, dbuf); 782 } 783 784 // make the user specific temporary directory. Returns true if 785 // the directory exists and is secure upon return. Returns false 786 // if the directory exists but is either a symlink, is otherwise 787 // insecure, or if an error occurred. 788 // 789 static bool make_user_tmp_dir(const char* dirname) { 790 791 // create the directory with 0755 permissions. note that the directory 792 // will be owned by euid::egid, which may not be the same as uid::gid. 793 // 794 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { 795 if (errno == EEXIST) { 796 // The directory already exists and was probably created by another 797 // JVM instance. However, this could also be the result of a 798 // deliberate symlink. Verify that the existing directory is safe. 799 // 800 if (!is_directory_secure(dirname)) { 801 // directory is not secure 802 if (PrintMiscellaneous && Verbose) { 803 warning("%s directory is insecure\n", dirname); 804 } 805 return false; 806 } 807 } 808 else { 809 // we encountered some other failure while attempting 810 // to create the directory 811 // 812 if (PrintMiscellaneous && Verbose) { 813 warning("could not create directory %s: %s\n", 814 dirname, os::strerror(errno)); 815 } 816 return false; 817 } 818 } 819 return true; 820 } 821 822 // create the shared memory file resources 823 // 824 // This method creates the shared memory file with the given size 825 // This method also creates the user specific temporary directory, if 826 // it does not yet exist. 827 // 828 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { 829 830 // make the user temporary directory 831 if (!make_user_tmp_dir(dirname)) { 832 // could not make/find the directory or the found directory 833 // was not secure 834 return -1; 835 } 836 837 int saved_cwd_fd; 838 // open the directory and set the current working directory to it 839 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); 840 if (dirp == NULL) { 841 // Directory doesn't exist or is insecure, so cannot create shared 842 // memory file. 843 return -1; 844 } 845 846 // Open the filename in the current directory. 847 // Cannot use O_TRUNC here; truncation of an existing file has to happen 848 // after the is_file_secure() check below. 849 int result; 850 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result); 851 if (result == OS_ERR) { 852 if (PrintMiscellaneous && Verbose) { 853 if (errno == ELOOP) { 854 warning("file %s is a symlink and is not secure\n", filename); 855 } else { 856 warning("could not create file %s: %s\n", filename, os::strerror(errno)); 857 } 858 } 859 // close the directory and reset the current working directory 860 close_directory_secure_cwd(dirp, saved_cwd_fd); 861 862 return -1; 863 } 864 // close the directory and reset the current working directory 865 close_directory_secure_cwd(dirp, saved_cwd_fd); 866 867 // save the file descriptor 868 int fd = result; 869 870 // check to see if the file is secure 871 if (!is_file_secure(fd, filename)) { 872 ::close(fd); 873 return -1; 874 } 875 876 // truncate the file to get rid of any existing data 877 RESTARTABLE(::ftruncate(fd, (off_t)0), result); 878 if (result == OS_ERR) { 879 if (PrintMiscellaneous && Verbose) { 880 warning("could not truncate shared memory file: %s\n", os::strerror(errno)); 881 } 882 ::close(fd); 883 return -1; 884 } 885 // set the file size 886 RESTARTABLE(::ftruncate(fd, (off_t)size), result); 887 if (result == OS_ERR) { 888 if (PrintMiscellaneous && Verbose) { 889 warning("could not set shared memory file size: %s\n", os::strerror(errno)); 890 } 891 ::close(fd); 892 return -1; 893 } 894 895 return fd; 896 } 897 898 // open the shared memory file for the given user and vmid. returns 899 // the file descriptor for the open file or -1 if the file could not 900 // be opened. 901 // 902 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 903 904 // open the file 905 int result; 906 RESTARTABLE(::open(filename, oflags), result); 907 if (result == OS_ERR) { 908 if (errno == ENOENT) { 909 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 910 "Process not found", OS_ERR); 911 } 912 else if (errno == EACCES) { 913 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), 914 "Permission denied", OS_ERR); 915 } 916 else { 917 THROW_MSG_(vmSymbols::java_io_IOException(), 918 os::strerror(errno), OS_ERR); 919 } 920 } 921 int fd = result; 922 923 // check to see if the file is secure 924 if (!is_file_secure(fd, filename)) { 925 ::close(fd); 926 return -1; 927 } 928 929 return fd; 930 } 931 932 // create a named shared memory region. returns the address of the 933 // memory region on success or NULL on failure. A return value of 934 // NULL will ultimately disable the shared memory feature. 935 // 936 // On Solaris, the name space for shared memory objects 937 // is the file system name space. 938 // 939 // A monitoring application attaching to a JVM does not need to know 940 // the file system name of the shared memory object. However, it may 941 // be convenient for applications to discover the existence of newly 942 // created and terminating JVMs by watching the file system name space 943 // for files being created or removed. 944 // 945 static char* mmap_create_shared(size_t size) { 946 947 int result; 948 int fd; 949 char* mapAddress; 950 951 int vmid = os::current_process_id(); 952 953 char* user_name = get_user_name(geteuid()); 954 955 if (user_name == NULL) 956 return NULL; 957 958 char* dirname = get_user_tmp_dir(user_name); 959 char* filename = get_sharedmem_filename(dirname, vmid); 960 961 // get the short filename 962 char* short_filename = strrchr(filename, '/'); 963 if (short_filename == NULL) { 964 short_filename = filename; 965 } else { 966 short_filename++; 967 } 968 969 // cleanup any stale shared memory files 970 cleanup_sharedmem_resources(dirname); 971 972 assert(((size > 0) && (size % os::vm_page_size() == 0)), 973 "unexpected PerfMemory region size"); 974 975 fd = create_sharedmem_resources(dirname, short_filename, size); 976 977 FREE_C_HEAP_ARRAY(char, user_name); 978 FREE_C_HEAP_ARRAY(char, dirname); 979 980 if (fd == -1) { 981 FREE_C_HEAP_ARRAY(char, filename); 982 return NULL; 983 } 984 985 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); 986 987 result = ::close(fd); 988 assert(result != OS_ERR, "could not close file"); 989 990 if (mapAddress == MAP_FAILED) { 991 if (PrintMiscellaneous && Verbose) { 992 warning("mmap failed - %s\n", os::strerror(errno)); 993 } 994 remove_file(filename); 995 FREE_C_HEAP_ARRAY(char, filename); 996 return NULL; 997 } 998 999 // save the file name for use in delete_shared_memory() 1000 backing_store_file_name = filename; 1001 1002 // clear the shared memory region 1003 (void)::memset((void*) mapAddress, 0, size); 1004 1005 // it does not go through os api, the operation has to record from here 1006 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, 1007 size, CURRENT_PC, mtInternal); 1008 1009 return mapAddress; 1010 } 1011 1012 // release a named shared memory region 1013 // 1014 static void unmap_shared(char* addr, size_t bytes) { 1015 os::release_memory(addr, bytes); 1016 } 1017 1018 // create the PerfData memory region in shared memory. 1019 // 1020 static char* create_shared_memory(size_t size) { 1021 1022 // create the shared memory region. 1023 return mmap_create_shared(size); 1024 } 1025 1026 // delete the shared PerfData memory region 1027 // 1028 static void delete_shared_memory(char* addr, size_t size) { 1029 1030 // cleanup the persistent shared memory resources. since DestroyJavaVM does 1031 // not support unloading of the JVM, unmapping of the memory resource is 1032 // not performed. The memory will be reclaimed by the OS upon termination of 1033 // the process. The backing store file is deleted from the file system. 1034 1035 assert(!PerfDisableSharedMem, "shouldn't be here"); 1036 1037 if (backing_store_file_name != NULL) { 1038 remove_file(backing_store_file_name); 1039 // Don't.. Free heap memory could deadlock os::abort() if it is called 1040 // from signal handler. OS will reclaim the heap memory. 1041 // FREE_C_HEAP_ARRAY(char, backing_store_file_name); 1042 backing_store_file_name = NULL; 1043 } 1044 } 1045 1046 // return the size of the file for the given file descriptor 1047 // or 0 if it is not a valid size for a shared memory file 1048 // 1049 static size_t sharedmem_filesize(int fd, TRAPS) { 1050 1051 struct stat statbuf; 1052 int result; 1053 1054 RESTARTABLE(::fstat(fd, &statbuf), result); 1055 if (result == OS_ERR) { 1056 if (PrintMiscellaneous && Verbose) { 1057 warning("fstat failed: %s\n", os::strerror(errno)); 1058 } 1059 THROW_MSG_0(vmSymbols::java_io_IOException(), 1060 "Could not determine PerfMemory size"); 1061 } 1062 1063 if ((statbuf.st_size == 0) || 1064 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { 1065 THROW_MSG_0(vmSymbols::java_lang_Exception(), 1066 "Invalid PerfMemory size"); 1067 } 1068 1069 return (size_t)statbuf.st_size; 1070 } 1071 1072 // attach to a named shared memory region. 1073 // 1074 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { 1075 1076 char* mapAddress; 1077 int result; 1078 int fd; 1079 size_t size = 0; 1080 const char* luser = NULL; 1081 1082 int mmap_prot; 1083 int file_flags; 1084 1085 ResourceMark rm; 1086 1087 // map the high level access mode to the appropriate permission 1088 // constructs for the file and the shared memory mapping. 1089 if (mode == PerfMemory::PERF_MODE_RO) { 1090 mmap_prot = PROT_READ; 1091 file_flags = O_RDONLY | O_NOFOLLOW; 1092 } 1093 else if (mode == PerfMemory::PERF_MODE_RW) { 1094 #ifdef LATER 1095 mmap_prot = PROT_READ | PROT_WRITE; 1096 file_flags = O_RDWR | O_NOFOLLOW; 1097 #else 1098 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1099 "Unsupported access mode"); 1100 #endif 1101 } 1102 else { 1103 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1104 "Illegal access mode"); 1105 } 1106 1107 if (user == NULL || strlen(user) == 0) { 1108 luser = get_user_name(vmid, CHECK); 1109 } 1110 else { 1111 luser = user; 1112 } 1113 1114 if (luser == NULL) { 1115 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1116 "Could not map vmid to user Name"); 1117 } 1118 1119 char* dirname = get_user_tmp_dir(luser); 1120 1121 // since we don't follow symbolic links when creating the backing 1122 // store file, we don't follow them when attaching either. 1123 // 1124 if (!is_directory_secure(dirname)) { 1125 FREE_C_HEAP_ARRAY(char, dirname); 1126 if (luser != user) { 1127 FREE_C_HEAP_ARRAY(char, luser); 1128 } 1129 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), 1130 "Process not found"); 1131 } 1132 1133 char* filename = get_sharedmem_filename(dirname, vmid); 1134 1135 // copy heap memory to resource memory. the open_sharedmem_file 1136 // method below need to use the filename, but could throw an 1137 // exception. using a resource array prevents the leak that 1138 // would otherwise occur. 1139 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); 1140 strcpy(rfilename, filename); 1141 1142 // free the c heap resources that are no longer needed 1143 if (luser != user) FREE_C_HEAP_ARRAY(char, luser); 1144 FREE_C_HEAP_ARRAY(char, dirname); 1145 FREE_C_HEAP_ARRAY(char, filename); 1146 1147 // open the shared memory file for the give vmid 1148 fd = open_sharedmem_file(rfilename, file_flags, THREAD); 1149 1150 if (fd == OS_ERR) { 1151 return; 1152 } 1153 1154 if (HAS_PENDING_EXCEPTION) { 1155 ::close(fd); 1156 return; 1157 } 1158 1159 if (*sizep == 0) { 1160 size = sharedmem_filesize(fd, CHECK); 1161 } else { 1162 size = *sizep; 1163 } 1164 1165 assert(size > 0, "unexpected size <= 0"); 1166 1167 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); 1168 1169 result = ::close(fd); 1170 assert(result != OS_ERR, "could not close file"); 1171 1172 if (mapAddress == MAP_FAILED) { 1173 if (PrintMiscellaneous && Verbose) { 1174 warning("mmap failed: %s\n", os::strerror(errno)); 1175 } 1176 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), 1177 "Could not map PerfMemory"); 1178 } 1179 1180 // it does not go through os api, the operation has to record from here 1181 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, 1182 size, CURRENT_PC, mtInternal); 1183 1184 *addr = mapAddress; 1185 *sizep = size; 1186 1187 if (PerfTraceMemOps) { 1188 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at " 1189 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress); 1190 } 1191 } 1192 1193 1194 1195 1196 // create the PerfData memory region 1197 // 1198 // This method creates the memory region used to store performance 1199 // data for the JVM. The memory may be created in standard or 1200 // shared memory. 1201 // 1202 void PerfMemory::create_memory_region(size_t size) { 1203 1204 if (PerfDisableSharedMem) { 1205 // do not share the memory for the performance data. 1206 _start = create_standard_memory(size); 1207 } 1208 else { 1209 _start = create_shared_memory(size); 1210 if (_start == NULL) { 1211 1212 // creation of the shared memory region failed, attempt 1213 // to create a contiguous, non-shared memory region instead. 1214 // 1215 if (PrintMiscellaneous && Verbose) { 1216 warning("Reverting to non-shared PerfMemory region.\n"); 1217 } 1218 PerfDisableSharedMem = true; 1219 _start = create_standard_memory(size); 1220 } 1221 } 1222 1223 if (_start != NULL) _capacity = size; 1224 1225 } 1226 1227 // delete the PerfData memory region 1228 // 1229 // This method deletes the memory region used to store performance 1230 // data for the JVM. The memory region indicated by the <address, size> 1231 // tuple will be inaccessible after a call to this method. 1232 // 1233 void PerfMemory::delete_memory_region() { 1234 1235 assert((start() != NULL && capacity() > 0), "verify proper state"); 1236 1237 // If user specifies PerfDataSaveFile, it will save the performance data 1238 // to the specified file name no matter whether PerfDataSaveToFile is specified 1239 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag 1240 // -XX:+PerfDataSaveToFile. 1241 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { 1242 save_memory_to_file(start(), capacity()); 1243 } 1244 1245 if (PerfDisableSharedMem) { 1246 delete_standard_memory(start(), capacity()); 1247 } 1248 else { 1249 delete_shared_memory(start(), capacity()); 1250 } 1251 } 1252 1253 // attach to the PerfData memory region for another JVM 1254 // 1255 // This method returns an <address, size> tuple that points to 1256 // a memory buffer that is kept reasonably synchronized with 1257 // the PerfData memory region for the indicated JVM. This 1258 // buffer may be kept in synchronization via shared memory 1259 // or some other mechanism that keeps the buffer updated. 1260 // 1261 // If the JVM chooses not to support the attachability feature, 1262 // this method should throw an UnsupportedOperation exception. 1263 // 1264 // This implementation utilizes named shared memory to map 1265 // the indicated process's PerfData memory region into this JVMs 1266 // address space. 1267 // 1268 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { 1269 1270 if (vmid == 0 || vmid == os::current_process_id()) { 1271 *addrp = start(); 1272 *sizep = capacity(); 1273 return; 1274 } 1275 1276 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); 1277 } 1278 1279 // detach from the PerfData memory region of another JVM 1280 // 1281 // This method detaches the PerfData memory region of another 1282 // JVM, specified as an <address, size> tuple of a buffer 1283 // in this process's address space. This method may perform 1284 // arbitrary actions to accomplish the detachment. The memory 1285 // region specified by <address, size> will be inaccessible after 1286 // a call to this method. 1287 // 1288 // If the JVM chooses not to support the attachability feature, 1289 // this method should throw an UnsupportedOperation exception. 1290 // 1291 // This implementation utilizes named shared memory to detach 1292 // the indicated process's PerfData memory region from this 1293 // process's address space. 1294 // 1295 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { 1296 1297 assert(addr != 0, "address sanity check"); 1298 assert(bytes > 0, "capacity sanity check"); 1299 1300 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { 1301 // prevent accidental detachment of this process's PerfMemory region 1302 return; 1303 } 1304 1305 unmap_shared(addr, bytes); 1306 }