1 /*

     2  * Copyright (c) 2001, 2017, 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);