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_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   char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
 527   errno = 0;
 528   while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
 529 
 530     // check if the directory entry is a hsperfdata file
 531     if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
 532       continue;
 533     }
 534 
 535     char* usrdir_name = NEW_C_HEAP_ARRAY(char,
 536                   strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
 537     strcpy(usrdir_name, tmpdirname);
 538     strcat(usrdir_name, "/");
 539     strcat(usrdir_name, dentry->d_name);
 540 
 541     // open the user directory
 542     DIR* subdirp = open_directory_secure(usrdir_name);
 543 
 544     if (subdirp == NULL) {
 545       FREE_C_HEAP_ARRAY(char, usrdir_name);
 546       continue;
 547     }
 548 
 549     // Since we don't create the backing store files in directories
 550     // pointed to by symbolic links, we also don't follow them when
 551     // looking for the files. We check for a symbolic link after the
 552     // call to opendir in order to eliminate a small window where the
 553     // symlink can be exploited.
 554     //
 555     if (!is_directory_secure(usrdir_name)) {
 556       FREE_C_HEAP_ARRAY(char, usrdir_name);
 557       os::closedir(subdirp);
 558       continue;
 559     }
 560 
 561     struct dirent* udentry;
 562     char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
 563     errno = 0;
 564     while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
 565 
 566       if (filename_to_pid(udentry->d_name) == vmid) {
 567         struct stat statbuf;
 568         int result;
 569 
 570         char* filename = NEW_C_HEAP_ARRAY(char,
 571                  strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
 572 
 573         strcpy(filename, usrdir_name);
 574         strcat(filename, "/");
 575         strcat(filename, udentry->d_name);
 576 
 577         // don't follow symbolic links for the file
 578         RESTARTABLE(::lstat(filename, &statbuf), result);
 579         if (result == OS_ERR) {
 580            FREE_C_HEAP_ARRAY(char, filename);
 581            continue;
 582         }
 583 
 584         // skip over files that are not regular files.
 585         if (!S_ISREG(statbuf.st_mode)) {
 586           FREE_C_HEAP_ARRAY(char, filename);
 587           continue;
 588         }
 589 
 590         // compare and save filename with latest creation time
 591         if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
 592 
 593           if (statbuf.st_ctime > oldest_ctime) {
 594             char* user = strchr(dentry->d_name, '_') + 1;
 595 
 596             if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user);
 597             oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal);
 598 
 599             strcpy(oldest_user, user);
 600             oldest_ctime = statbuf.st_ctime;
 601           }
 602         }
 603 
 604         FREE_C_HEAP_ARRAY(char, filename);
 605       }
 606     }
 607     os::closedir(subdirp);
 608     FREE_C_HEAP_ARRAY(char, udbuf);
 609     FREE_C_HEAP_ARRAY(char, usrdir_name);
 610   }
 611   os::closedir(tmpdirp);
 612   FREE_C_HEAP_ARRAY(char, tdbuf);
 613 
 614   return(oldest_user);
 615 }
 616 
 617 // return the name of the user that owns the JVM indicated by the given vmid.
 618 //
 619 static char* get_user_name(int vmid, TRAPS) {
 620 
 621   char psinfo_name[PATH_MAX];
 622   int result;
 623 
 624   snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid);
 625 
 626   RESTARTABLE(::open(psinfo_name, O_RDONLY), result);
 627 
 628   if (result != OS_ERR) {
 629     int fd = result;
 630 
 631     psinfo_t psinfo;
 632     char* addr = (char*)&psinfo;
 633 
 634     for (size_t remaining = sizeof(psinfo_t); remaining > 0;) {
 635 
 636       RESTARTABLE(::read(fd, addr, remaining), result);
 637       if (result == OS_ERR) {
 638         ::close(fd);
 639         THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error");
 640       } else {
 641         remaining-=result;
 642         addr+=result;
 643       }
 644     }
 645 
 646     ::close(fd);
 647 
 648     // get the user name for the effective user id of the process
 649     char* user_name = get_user_name(psinfo.pr_euid);
 650 
 651     return user_name;
 652   }
 653 
 654   if (result == OS_ERR && errno == EACCES) {
 655 
 656     // In this case, the psinfo file for the process id existed,
 657     // but we didn't have permission to access it.
 658     THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
 659                 os::strerror(errno));
 660   }
 661 
 662   // at this point, we don't know if the process id itself doesn't
 663   // exist or if the psinfo file doesn't exit. If the psinfo file
 664   // doesn't exist, then we are running on Solaris 2.5.1 or earlier.
 665   // since the structured procfs and old procfs interfaces can't be
 666   // mixed, we attempt to find the file through a directory search.
 667 
 668   return get_user_name_slow(vmid, THREAD);
 669 }
 670 
 671 // return the file name of the backing store file for the named
 672 // shared memory region for the given user name and vmid.
 673 //
 674 // the caller is expected to free the allocated memory.
 675 //
 676 static char* get_sharedmem_filename(const char* dirname, int vmid) {
 677 
 678   // add 2 for the file separator and a NULL terminator.
 679   size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
 680 
 681   char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
 682   snprintf(name, nbytes, "%s/%d", dirname, vmid);
 683 
 684   return name;
 685 }
 686 
 687 
 688 // remove file
 689 //
 690 // this method removes the file specified by the given path
 691 //
 692 static void remove_file(const char* path) {
 693 
 694   int result;
 695 
 696   // if the file is a directory, the following unlink will fail. since
 697   // we don't expect to find directories in the user temp directory, we
 698   // won't try to handle this situation. even if accidentially or
 699   // maliciously planted, the directory's presence won't hurt anything.
 700   //
 701   RESTARTABLE(::unlink(path), result);
 702   if (PrintMiscellaneous && Verbose && result == OS_ERR) {
 703     if (errno != ENOENT) {
 704       warning("Could not unlink shared memory backing"
 705               " store file %s : %s\n", path, os::strerror(errno));
 706     }
 707   }
 708 }
 709 
 710 
 711 // cleanup stale shared memory resources
 712 //
 713 // This method attempts to remove all stale shared memory files in
 714 // the named user temporary directory. It scans the named directory
 715 // for files matching the pattern ^$[0-9]*$. For each file found, the
 716 // process id is extracted from the file name and a test is run to
 717 // determine if the process is alive. If the process is not alive,
 718 // any stale file resources are removed.
 719 //
 720 static void cleanup_sharedmem_resources(const char* dirname) {
 721 
 722   int saved_cwd_fd;
 723   // open the directory
 724   DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
 725   if (dirp == NULL) {
 726     // directory doesn't exist or is insecure, so there is nothing to cleanup
 727     return;
 728   }
 729 
 730   // for each entry in the directory that matches the expected file
 731   // name pattern, determine if the file resources are stale and if
 732   // so, remove the file resources. Note, instrumented HotSpot processes
 733   // for this user may start and/or terminate during this search and
 734   // remove or create new files in this directory. The behavior of this
 735   // loop under these conditions is dependent upon the implementation of
 736   // opendir/readdir.
 737   //
 738   struct dirent* entry;
 739   char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
 740 
 741   errno = 0;
 742   while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
 743 
 744     pid_t pid = filename_to_pid(entry->d_name);
 745 
 746     if (pid == 0) {
 747 
 748       if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
 749 
 750         // attempt to remove all unexpected files, except "." and ".."
 751         unlink(entry->d_name);
 752       }
 753 
 754       errno = 0;
 755       continue;
 756     }
 757 
 758     // we now have a file name that converts to a valid integer
 759     // that could represent a process id . if this process id
 760     // matches the current process id or the process is not running,
 761     // then remove the stale file resources.
 762     //
 763     // process liveness is detected by sending signal number 0 to
 764     // the process id (see kill(2)). if kill determines that the
 765     // process does not exist, then the file resources are removed.
 766     // if kill determines that that we don't have permission to
 767     // signal the process, then the file resources are assumed to
 768     // be stale and are removed because the resources for such a
 769     // process should be in a different user specific directory.
 770     //
 771     if ((pid == os::current_process_id()) ||
 772         (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
 773 
 774         unlink(entry->d_name);
 775     }
 776     errno = 0;
 777   }
 778 
 779   // close the directory and reset the current working directory
 780   close_directory_secure_cwd(dirp, saved_cwd_fd);
 781 
 782   FREE_C_HEAP_ARRAY(char, dbuf);
 783 }
 784 
 785 // make the user specific temporary directory. Returns true if
 786 // the directory exists and is secure upon return. Returns false
 787 // if the directory exists but is either a symlink, is otherwise
 788 // insecure, or if an error occurred.
 789 //
 790 static bool make_user_tmp_dir(const char* dirname) {
 791 
 792   // create the directory with 0755 permissions. note that the directory
 793   // will be owned by euid::egid, which may not be the same as uid::gid.
 794   //
 795   if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
 796     if (errno == EEXIST) {
 797       // The directory already exists and was probably created by another
 798       // JVM instance. However, this could also be the result of a
 799       // deliberate symlink. Verify that the existing directory is safe.
 800       //
 801       if (!is_directory_secure(dirname)) {
 802         // directory is not secure
 803         if (PrintMiscellaneous && Verbose) {
 804           warning("%s directory is insecure\n", dirname);
 805         }
 806         return false;
 807       }
 808     }
 809     else {
 810       // we encountered some other failure while attempting
 811       // to create the directory
 812       //
 813       if (PrintMiscellaneous && Verbose) {
 814         warning("could not create directory %s: %s\n",
 815                 dirname, os::strerror(errno));
 816       }
 817       return false;
 818     }
 819   }
 820   return true;
 821 }
 822 
 823 // create the shared memory file resources
 824 //
 825 // This method creates the shared memory file with the given size
 826 // This method also creates the user specific temporary directory, if
 827 // it does not yet exist.
 828 //
 829 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
 830 
 831   // make the user temporary directory
 832   if (!make_user_tmp_dir(dirname)) {
 833     // could not make/find the directory or the found directory
 834     // was not secure
 835     return -1;
 836   }
 837 
 838   int saved_cwd_fd;
 839   // open the directory and set the current working directory to it
 840   DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
 841   if (dirp == NULL) {
 842     // Directory doesn't exist or is insecure, so cannot create shared
 843     // memory file.
 844     return -1;
 845   }
 846 
 847   // Open the filename in the current directory.
 848   // Cannot use O_TRUNC here; truncation of an existing file has to happen
 849   // after the is_file_secure() check below.
 850   int result;
 851   RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result);
 852   if (result == OS_ERR) {
 853     if (PrintMiscellaneous && Verbose) {
 854       if (errno == ELOOP) {
 855         warning("file %s is a symlink and is not secure\n", filename);
 856       } else {
 857         warning("could not create file %s: %s\n", filename, os::strerror(errno));
 858       }
 859     }
 860     // close the directory and reset the current working directory
 861     close_directory_secure_cwd(dirp, saved_cwd_fd);
 862 
 863     return -1;
 864   }
 865   // close the directory and reset the current working directory
 866   close_directory_secure_cwd(dirp, saved_cwd_fd);
 867 
 868   // save the file descriptor
 869   int fd = result;
 870 
 871   // check to see if the file is secure
 872   if (!is_file_secure(fd, filename)) {
 873     ::close(fd);
 874     return -1;
 875   }
 876 
 877   // truncate the file to get rid of any existing data
 878   RESTARTABLE(::ftruncate(fd, (off_t)0), result);
 879   if (result == OS_ERR) {
 880     if (PrintMiscellaneous && Verbose) {
 881       warning("could not truncate shared memory file: %s\n", os::strerror(errno));
 882     }
 883     ::close(fd);
 884     return -1;
 885   }
 886   // set the file size
 887   RESTARTABLE(::ftruncate(fd, (off_t)size), result);
 888   if (result == OS_ERR) {
 889     if (PrintMiscellaneous && Verbose) {
 890       warning("could not set shared memory file size: %s\n", os::strerror(errno));
 891     }
 892     ::close(fd);
 893     return -1;
 894   }
 895 
 896   return fd;
 897 }
 898 
 899 // open the shared memory file for the given user and vmid. returns
 900 // the file descriptor for the open file or -1 if the file could not
 901 // be opened.
 902 //
 903 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
 904 
 905   // open the file
 906   int result;
 907   RESTARTABLE(::open(filename, oflags), result);
 908   if (result == OS_ERR) {
 909     if (errno == ENOENT) {
 910       THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
 911                  "Process not found", OS_ERR);
 912     }
 913     else if (errno == EACCES) {
 914       THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
 915                  "Permission denied", OS_ERR);
 916     }
 917     else {
 918       THROW_MSG_(vmSymbols::java_io_IOException(),
 919                  os::strerror(errno), OS_ERR);
 920     }
 921   }
 922   int fd = result;
 923 
 924   // check to see if the file is secure
 925   if (!is_file_secure(fd, filename)) {
 926     ::close(fd);
 927     return -1;
 928   }
 929 
 930   return fd;
 931 }
 932 
 933 // create a named shared memory region. returns the address of the
 934 // memory region on success or NULL on failure. A return value of
 935 // NULL will ultimately disable the shared memory feature.
 936 //
 937 // On Solaris, the name space for shared memory objects
 938 // is the file system name space.
 939 //
 940 // A monitoring application attaching to a JVM does not need to know
 941 // the file system name of the shared memory object. However, it may
 942 // be convenient for applications to discover the existence of newly
 943 // created and terminating JVMs by watching the file system name space
 944 // for files being created or removed.
 945 //
 946 static char* mmap_create_shared(size_t size) {
 947 
 948   int result;
 949   int fd;
 950   char* mapAddress;
 951 
 952   int vmid = os::current_process_id();
 953 
 954   char* user_name = get_user_name(geteuid());
 955 
 956   if (user_name == NULL)
 957     return NULL;
 958 
 959   char* dirname = get_user_tmp_dir(user_name);
 960   char* filename = get_sharedmem_filename(dirname, vmid);
 961 
 962   // get the short filename
 963   char* short_filename = strrchr(filename, '/');
 964   if (short_filename == NULL) {
 965     short_filename = filename;
 966   } else {
 967     short_filename++;
 968   }
 969 
 970   // cleanup any stale shared memory files
 971   cleanup_sharedmem_resources(dirname);
 972 
 973   assert(((size > 0) && (size % os::vm_page_size() == 0)),
 974          "unexpected PerfMemory region size");
 975 
 976   fd = create_sharedmem_resources(dirname, short_filename, size);
 977 
 978   FREE_C_HEAP_ARRAY(char, user_name);
 979   FREE_C_HEAP_ARRAY(char, dirname);
 980 
 981   if (fd == -1) {
 982     FREE_C_HEAP_ARRAY(char, filename);
 983     return NULL;
 984   }
 985 
 986   mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
 987 
 988   result = ::close(fd);
 989   assert(result != OS_ERR, "could not close file");
 990 
 991   if (mapAddress == MAP_FAILED) {
 992     if (PrintMiscellaneous && Verbose) {
 993       warning("mmap failed -  %s\n", os::strerror(errno));
 994     }
 995     remove_file(filename);
 996     FREE_C_HEAP_ARRAY(char, filename);
 997     return NULL;
 998   }
 999 
1000   // save the file name for use in delete_shared_memory()
1001   backing_store_file_name = filename;
1002 
1003   // clear the shared memory region
1004   (void)::memset((void*) mapAddress, 0, size);
1005 
1006   // it does not go through os api, the operation has to record from here
1007   MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress,
1008     size, CURRENT_PC, mtInternal);
1009 
1010   return mapAddress;
1011 }
1012 
1013 // release a named shared memory region
1014 //
1015 static void unmap_shared(char* addr, size_t bytes) {
1016   os::release_memory(addr, bytes);
1017 }
1018 
1019 // create the PerfData memory region in shared memory.
1020 //
1021 static char* create_shared_memory(size_t size) {
1022 
1023   // create the shared memory region.
1024   return mmap_create_shared(size);
1025 }
1026 
1027 // delete the shared PerfData memory region
1028 //
1029 static void delete_shared_memory(char* addr, size_t size) {
1030 
1031   // cleanup the persistent shared memory resources. since DestroyJavaVM does
1032   // not support unloading of the JVM, unmapping of the memory resource is
1033   // not performed. The memory will be reclaimed by the OS upon termination of
1034   // the process. The backing store file is deleted from the file system.
1035 
1036   assert(!PerfDisableSharedMem, "shouldn't be here");
1037 
1038   if (backing_store_file_name != NULL) {
1039     remove_file(backing_store_file_name);
1040     // Don't.. Free heap memory could deadlock os::abort() if it is called
1041     // from signal handler. OS will reclaim the heap memory.
1042     // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
1043     backing_store_file_name = NULL;
1044   }
1045 }
1046 
1047 // return the size of the file for the given file descriptor
1048 // or 0 if it is not a valid size for a shared memory file
1049 //
1050 static size_t sharedmem_filesize(int fd, TRAPS) {
1051 
1052   struct stat statbuf;
1053   int result;
1054 
1055   RESTARTABLE(::fstat(fd, &statbuf), result);
1056   if (result == OS_ERR) {
1057     if (PrintMiscellaneous && Verbose) {
1058       warning("fstat failed: %s\n", os::strerror(errno));
1059     }
1060     THROW_MSG_0(vmSymbols::java_io_IOException(),
1061                 "Could not determine PerfMemory size");
1062   }
1063 
1064   if ((statbuf.st_size == 0) ||
1065      ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
1066     THROW_MSG_0(vmSymbols::java_lang_Exception(),
1067                 "Invalid PerfMemory size");
1068   }
1069 
1070   return (size_t)statbuf.st_size;
1071 }
1072 
1073 // attach to a named shared memory region.
1074 //
1075 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
1076 
1077   char* mapAddress;
1078   int result;
1079   int fd;
1080   size_t size = 0;
1081   const char* luser = NULL;
1082 
1083   int mmap_prot;
1084   int file_flags;
1085 
1086   ResourceMark rm;
1087 
1088   // map the high level access mode to the appropriate permission
1089   // constructs for the file and the shared memory mapping.
1090   if (mode == PerfMemory::PERF_MODE_RO) {
1091     mmap_prot = PROT_READ;
1092     file_flags = O_RDONLY | O_NOFOLLOW;
1093   }
1094   else if (mode == PerfMemory::PERF_MODE_RW) {
1095 #ifdef LATER
1096     mmap_prot = PROT_READ | PROT_WRITE;
1097     file_flags = O_RDWR | O_NOFOLLOW;
1098 #else
1099     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1100               "Unsupported access mode");
1101 #endif
1102   }
1103   else {
1104     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1105               "Illegal access mode");
1106   }
1107 
1108   if (user == NULL || strlen(user) == 0) {
1109     luser = get_user_name(vmid, CHECK);
1110   }
1111   else {
1112     luser = user;
1113   }
1114 
1115   if (luser == NULL) {
1116     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1117               "Could not map vmid to user Name");
1118   }
1119 
1120   char* dirname = get_user_tmp_dir(luser);
1121 
1122   // since we don't follow symbolic links when creating the backing
1123   // store file, we don't follow them when attaching either.
1124   //
1125   if (!is_directory_secure(dirname)) {
1126     FREE_C_HEAP_ARRAY(char, dirname);
1127     if (luser != user) {
1128       FREE_C_HEAP_ARRAY(char, luser);
1129     }
1130     THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1131               "Process not found");
1132   }
1133 
1134   char* filename = get_sharedmem_filename(dirname, vmid);
1135 
1136   // copy heap memory to resource memory. the open_sharedmem_file
1137   // method below need to use the filename, but could throw an
1138   // exception. using a resource array prevents the leak that
1139   // would otherwise occur.
1140   char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
1141   strcpy(rfilename, filename);
1142 
1143   // free the c heap resources that are no longer needed
1144   if (luser != user) FREE_C_HEAP_ARRAY(char, luser);
1145   FREE_C_HEAP_ARRAY(char, dirname);
1146   FREE_C_HEAP_ARRAY(char, filename);
1147 
1148   // open the shared memory file for the give vmid
1149   fd = open_sharedmem_file(rfilename, file_flags, THREAD);
1150 
1151   if (fd == OS_ERR) {
1152     return;
1153   }
1154 
1155   if (HAS_PENDING_EXCEPTION) {
1156     ::close(fd);
1157     return;
1158   }
1159 
1160   if (*sizep == 0) {
1161     size = sharedmem_filesize(fd, CHECK);
1162   } else {
1163     size = *sizep;
1164   }
1165 
1166   assert(size > 0, "unexpected size <= 0");
1167 
1168   mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
1169 
1170   result = ::close(fd);
1171   assert(result != OS_ERR, "could not close file");
1172 
1173   if (mapAddress == MAP_FAILED) {
1174     if (PrintMiscellaneous && Verbose) {
1175       warning("mmap failed: %s\n", os::strerror(errno));
1176     }
1177     THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
1178               "Could not map PerfMemory");
1179   }
1180 
1181   // it does not go through os api, the operation has to record from here
1182   MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress,
1183     size, CURRENT_PC, mtInternal);
1184 
1185   *addr = mapAddress;
1186   *sizep = size;
1187 
1188   log_debug(perf, memops)("mapped " SIZE_FORMAT " bytes for vmid %d at "
1189                           INTPTR_FORMAT, size, vmid, (void*)mapAddress);
1190 }
1191 
1192 // create the PerfData memory region
1193 //
1194 // This method creates the memory region used to store performance
1195 // data for the JVM. The memory may be created in standard or
1196 // shared memory.
1197 //
1198 void PerfMemory::create_memory_region(size_t size) {
1199 
1200   if (PerfDisableSharedMem) {
1201     // do not share the memory for the performance data.
1202     _start = create_standard_memory(size);
1203   }
1204   else {
1205     _start = create_shared_memory(size);
1206     if (_start == NULL) {
1207 
1208       // creation of the shared memory region failed, attempt
1209       // to create a contiguous, non-shared memory region instead.
1210       //
1211       if (PrintMiscellaneous && Verbose) {
1212         warning("Reverting to non-shared PerfMemory region.\n");
1213       }
1214       PerfDisableSharedMem = true;
1215       _start = create_standard_memory(size);
1216     }
1217   }
1218 
1219   if (_start != NULL) _capacity = size;
1220 
1221 }
1222 
1223 // delete the PerfData memory region
1224 //
1225 // This method deletes the memory region used to store performance
1226 // data for the JVM. The memory region indicated by the <address, size>
1227 // tuple will be inaccessible after a call to this method.
1228 //
1229 void PerfMemory::delete_memory_region() {
1230 
1231   assert((start() != NULL && capacity() > 0), "verify proper state");
1232 
1233   // If user specifies PerfDataSaveFile, it will save the performance data
1234   // to the specified file name no matter whether PerfDataSaveToFile is specified
1235   // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
1236   // -XX:+PerfDataSaveToFile.
1237   if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
1238     save_memory_to_file(start(), capacity());
1239   }
1240 
1241   if (PerfDisableSharedMem) {
1242     delete_standard_memory(start(), capacity());
1243   }
1244   else {
1245     delete_shared_memory(start(), capacity());
1246   }
1247 }
1248 
1249 // attach to the PerfData memory region for another JVM
1250 //
1251 // This method returns an <address, size> tuple that points to
1252 // a memory buffer that is kept reasonably synchronized with
1253 // the PerfData memory region for the indicated JVM. This
1254 // buffer may be kept in synchronization via shared memory
1255 // or some other mechanism that keeps the buffer updated.
1256 //
1257 // If the JVM chooses not to support the attachability feature,
1258 // this method should throw an UnsupportedOperation exception.
1259 //
1260 // This implementation utilizes named shared memory to map
1261 // the indicated process's PerfData memory region into this JVMs
1262 // address space.
1263 //
1264 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
1265 
1266   if (vmid == 0 || vmid == os::current_process_id()) {
1267      *addrp = start();
1268      *sizep = capacity();
1269      return;
1270   }
1271 
1272   mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
1273 }
1274 
1275 // detach from the PerfData memory region of another JVM
1276 //
1277 // This method detaches the PerfData memory region of another
1278 // JVM, specified as an <address, size> tuple of a buffer
1279 // in this process's address space. This method may perform
1280 // arbitrary actions to accomplish the detachment. The memory
1281 // region specified by <address, size> will be inaccessible after
1282 // a call to this method.
1283 //
1284 // If the JVM chooses not to support the attachability feature,
1285 // this method should throw an UnsupportedOperation exception.
1286 //
1287 // This implementation utilizes named shared memory to detach
1288 // the indicated process's PerfData memory region from this
1289 // process's address space.
1290 //
1291 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1292 
1293   assert(addr != 0, "address sanity check");
1294   assert(bytes > 0, "capacity sanity check");
1295 
1296   if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1297     // prevent accidental detachment of this process's PerfMemory region
1298     return;
1299   }
1300 
1301   unmap_shared(addr, bytes);
1302 }