Fri, 31 Oct 2014 17:09:14 -0700
Merge
1 /*
2 * Copyright (c) 2001, 2014, 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 */
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"
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 <pwd.h>
45 # include <procfs.h>
48 static char* backing_store_file_name = NULL; // name of the backing store
49 // file, if successfully created.
51 // Standard Memory Implementation Details
53 // create the PerfData memory region in standard memory.
54 //
55 static char* create_standard_memory(size_t size) {
57 // allocate an aligned chuck of memory
58 char* mapAddress = os::reserve_memory(size);
60 if (mapAddress == NULL) {
61 return NULL;
62 }
64 // commit memory
65 if (!os::commit_memory(mapAddress, size, !ExecMem)) {
66 if (PrintMiscellaneous && Verbose) {
67 warning("Could not commit PerfData memory\n");
68 }
69 os::release_memory(mapAddress, size);
70 return NULL;
71 }
73 return mapAddress;
74 }
76 // delete the PerfData memory region
77 //
78 static void delete_standard_memory(char* addr, size_t size) {
80 // there are no persistent external resources to cleanup for standard
81 // memory. since DestroyJavaVM does not support unloading of the JVM,
82 // cleanup of the memory resource is not performed. The memory will be
83 // reclaimed by the OS upon termination of the process.
84 //
85 return;
86 }
88 // save the specified memory region to the given file
89 //
90 // Note: this function might be called from signal handler (by os::abort()),
91 // don't allocate heap memory.
92 //
93 static void save_memory_to_file(char* addr, size_t size) {
95 const char* destfile = PerfMemory::get_perfdata_file_path();
96 assert(destfile[0] != '\0', "invalid PerfData file path");
98 int result;
100 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE),
101 result);;
102 if (result == OS_ERR) {
103 if (PrintMiscellaneous && Verbose) {
104 warning("Could not create Perfdata save file: %s: %s\n",
105 destfile, strerror(errno));
106 }
107 } else {
109 int fd = result;
111 for (size_t remaining = size; remaining > 0;) {
113 RESTARTABLE(::write(fd, addr, remaining), result);
114 if (result == OS_ERR) {
115 if (PrintMiscellaneous && Verbose) {
116 warning("Could not write Perfdata save file: %s: %s\n",
117 destfile, strerror(errno));
118 }
119 break;
120 }
121 remaining -= (size_t)result;
122 addr += result;
123 }
125 result = ::close(fd);
126 if (PrintMiscellaneous && Verbose) {
127 if (result == OS_ERR) {
128 warning("Could not close %s: %s\n", destfile, strerror(errno));
129 }
130 }
131 }
132 FREE_C_HEAP_ARRAY(char, destfile, mtInternal);
133 }
136 // Shared Memory Implementation Details
138 // Note: the solaris and linux shared memory implementation uses the mmap
139 // interface with a backing store file to implement named shared memory.
140 // Using the file system as the name space for shared memory allows a
141 // common name space to be supported across a variety of platforms. It
142 // also provides a name space that Java applications can deal with through
143 // simple file apis.
144 //
145 // The solaris and linux implementations store the backing store file in
146 // a user specific temporary directory located in the /tmp file system,
147 // which is always a local file system and is sometimes a RAM based file
148 // system.
150 // return the user specific temporary directory name.
151 //
152 // the caller is expected to free the allocated memory.
153 //
154 static char* get_user_tmp_dir(const char* user) {
156 const char* tmpdir = os::get_temp_directory();
157 const char* perfdir = PERFDATA_NAME;
158 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3;
159 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
161 // construct the path name to user specific tmp directory
162 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user);
164 return dirname;
165 }
167 // convert the given file name into a process id. if the file
168 // does not meet the file naming constraints, return 0.
169 //
170 static pid_t filename_to_pid(const char* filename) {
172 // a filename that doesn't begin with a digit is not a
173 // candidate for conversion.
174 //
175 if (!isdigit(*filename)) {
176 return 0;
177 }
179 // check if file name can be converted to an integer without
180 // any leftover characters.
181 //
182 char* remainder = NULL;
183 errno = 0;
184 pid_t pid = (pid_t)strtol(filename, &remainder, 10);
186 if (errno != 0) {
187 return 0;
188 }
190 // check for left over characters. If any, then the filename is
191 // not a candidate for conversion.
192 //
193 if (remainder != NULL && *remainder != '\0') {
194 return 0;
195 }
197 // successful conversion, return the pid
198 return pid;
199 }
202 // Check if the given statbuf is considered a secure directory for
203 // the backing store files. Returns true if the directory is considered
204 // a secure location. Returns false if the statbuf is a symbolic link or
205 // if an error occurred.
206 //
207 static bool is_statbuf_secure(struct stat *statp) {
208 if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) {
209 // The path represents a link or some non-directory file type,
210 // which is not what we expected. Declare it insecure.
211 //
212 return false;
213 }
214 // We have an existing directory, check if the permissions are safe.
215 //
216 if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) {
217 // The directory is open for writing and could be subjected
218 // to a symlink or a hard link attack. Declare it insecure.
219 //
220 return false;
221 }
222 // See if the uid of the directory matches the effective uid of the process.
223 //
224 if (statp->st_uid != geteuid()) {
225 // The directory was not created by this user, declare it insecure.
226 //
227 return false;
228 }
229 return true;
230 }
233 // Check if the given path is considered a secure directory for
234 // the backing store files. Returns true if the directory exists
235 // and is considered a secure location. Returns false if the path
236 // is a symbolic link or if an error occurred.
237 //
238 static bool is_directory_secure(const char* path) {
239 struct stat statbuf;
240 int result = 0;
242 RESTARTABLE(::lstat(path, &statbuf), result);
243 if (result == OS_ERR) {
244 return false;
245 }
247 // The path exists, see if it is secure.
248 return is_statbuf_secure(&statbuf);
249 }
252 // Check if the given directory file descriptor is considered a secure
253 // directory for the backing store files. Returns true if the directory
254 // exists and is considered a secure location. Returns false if the path
255 // is a symbolic link or if an error occurred.
256 //
257 static bool is_dirfd_secure(int dir_fd) {
258 struct stat statbuf;
259 int result = 0;
261 RESTARTABLE(::fstat(dir_fd, &statbuf), result);
262 if (result == OS_ERR) {
263 return false;
264 }
266 // The path exists, now check its mode.
267 return is_statbuf_secure(&statbuf);
268 }
271 // Check to make sure fd1 and fd2 are referencing the same file system object.
272 //
273 static bool is_same_fsobject(int fd1, int fd2) {
274 struct stat statbuf1;
275 struct stat statbuf2;
276 int result = 0;
278 RESTARTABLE(::fstat(fd1, &statbuf1), result);
279 if (result == OS_ERR) {
280 return false;
281 }
282 RESTARTABLE(::fstat(fd2, &statbuf2), result);
283 if (result == OS_ERR) {
284 return false;
285 }
287 if ((statbuf1.st_ino == statbuf2.st_ino) &&
288 (statbuf1.st_dev == statbuf2.st_dev)) {
289 return true;
290 } else {
291 return false;
292 }
293 }
296 // Open the directory of the given path and validate it.
297 // Return a DIR * of the open directory.
298 //
299 static DIR *open_directory_secure(const char* dirname) {
300 // Open the directory using open() so that it can be verified
301 // to be secure by calling is_dirfd_secure(), opendir() and then check
302 // to see if they are the same file system object. This method does not
303 // introduce a window of opportunity for the directory to be attacked that
304 // calling opendir() and is_directory_secure() does.
305 int result;
306 DIR *dirp = NULL;
307 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result);
308 if (result == OS_ERR) {
309 // Directory doesn't exist or is a symlink, so there is nothing to cleanup.
310 if (PrintMiscellaneous && Verbose) {
311 if (errno == ELOOP) {
312 warning("directory %s is a symlink and is not secure\n", dirname);
313 } else {
314 warning("could not open directory %s: %s\n", dirname, strerror(errno));
315 }
316 }
317 return dirp;
318 }
319 int fd = result;
321 // Determine if the open directory is secure.
322 if (!is_dirfd_secure(fd)) {
323 // The directory is not a secure directory.
324 os::close(fd);
325 return dirp;
326 }
328 // Open the directory.
329 dirp = ::opendir(dirname);
330 if (dirp == NULL) {
331 // The directory doesn't exist, close fd and return.
332 os::close(fd);
333 return dirp;
334 }
336 // Check to make sure fd and dirp are referencing the same file system object.
337 if (!is_same_fsobject(fd, dirp->dd_fd)) {
338 // The directory is not secure.
339 os::close(fd);
340 os::closedir(dirp);
341 dirp = NULL;
342 return dirp;
343 }
345 // Close initial open now that we know directory is secure
346 os::close(fd);
348 return dirp;
349 }
351 // NOTE: The code below uses fchdir(), open() and unlink() because
352 // fdopendir(), openat() and unlinkat() are not supported on all
353 // versions. Once the support for fdopendir(), openat() and unlinkat()
354 // is available on all supported versions the code can be changed
355 // to use these functions.
357 // Open the directory of the given path, validate it and set the
358 // current working directory to it.
359 // Return a DIR * of the open directory and the saved cwd fd.
360 //
361 static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) {
363 // Open the directory.
364 DIR* dirp = open_directory_secure(dirname);
365 if (dirp == NULL) {
366 // Directory doesn't exist or is insecure, so there is nothing to cleanup.
367 return dirp;
368 }
369 int fd = dirp->dd_fd;
371 // Open a fd to the cwd and save it off.
372 int result;
373 RESTARTABLE(::open(".", O_RDONLY), result);
374 if (result == OS_ERR) {
375 *saved_cwd_fd = -1;
376 } else {
377 *saved_cwd_fd = result;
378 }
380 // Set the current directory to dirname by using the fd of the directory.
381 result = fchdir(fd);
383 return dirp;
384 }
386 // Close the directory and restore the current working directory.
387 //
388 static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) {
390 int result;
391 // If we have a saved cwd change back to it and close the fd.
392 if (saved_cwd_fd != -1) {
393 result = fchdir(saved_cwd_fd);
394 ::close(saved_cwd_fd);
395 }
397 // Close the directory.
398 os::closedir(dirp);
399 }
401 // Check if the given file descriptor is considered a secure.
402 //
403 static bool is_file_secure(int fd, const char *filename) {
405 int result;
406 struct stat statbuf;
408 // Determine if the file is secure.
409 RESTARTABLE(::fstat(fd, &statbuf), result);
410 if (result == OS_ERR) {
411 if (PrintMiscellaneous && Verbose) {
412 warning("fstat failed on %s: %s\n", filename, strerror(errno));
413 }
414 return false;
415 }
416 if (statbuf.st_nlink > 1) {
417 // A file with multiple links is not expected.
418 if (PrintMiscellaneous && Verbose) {
419 warning("file %s has multiple links\n", filename);
420 }
421 return false;
422 }
423 return true;
424 }
426 // return the user name for the given user id
427 //
428 // the caller is expected to free the allocated memory.
429 //
430 static char* get_user_name(uid_t uid) {
432 struct passwd pwent;
434 // determine the max pwbuf size from sysconf, and hardcode
435 // a default if this not available through sysconf.
436 //
437 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
438 if (bufsize == -1)
439 bufsize = 1024;
441 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
443 #ifdef _GNU_SOURCE
444 struct passwd* p = NULL;
445 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);
446 #else // _GNU_SOURCE
447 struct passwd* p = getpwuid_r(uid, &pwent, pwbuf, (int)bufsize);
448 #endif // _GNU_SOURCE
450 if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {
451 if (PrintMiscellaneous && Verbose) {
452 if (p == NULL) {
453 warning("Could not retrieve passwd entry: %s\n",
454 strerror(errno));
455 }
456 else {
457 warning("Could not determine user name: %s\n",
458 p->pw_name == NULL ? "pw_name = NULL" :
459 "pw_name zero length");
460 }
461 }
462 FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal);
463 return NULL;
464 }
466 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal);
467 strcpy(user_name, p->pw_name);
469 FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal);
470 return user_name;
471 }
473 // return the name of the user that owns the process identified by vmid.
474 //
475 // This method uses a slow directory search algorithm to find the backing
476 // store file for the specified vmid and returns the user name, as determined
477 // by the user name suffix of the hsperfdata_<username> directory name.
478 //
479 // the caller is expected to free the allocated memory.
480 //
481 static char* get_user_name_slow(int vmid, TRAPS) {
483 // short circuit the directory search if the process doesn't even exist.
484 if (kill(vmid, 0) == OS_ERR) {
485 if (errno == ESRCH) {
486 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
487 "Process not found");
488 }
489 else /* EPERM */ {
490 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));
491 }
492 }
494 // directory search
495 char* oldest_user = NULL;
496 time_t oldest_ctime = 0;
498 const char* tmpdirname = os::get_temp_directory();
500 // open the temp directory
501 DIR* tmpdirp = open_directory_secure(tmpdirname);
502 if (tmpdirp == NULL) {
503 // Cannot open the directory to get the user name, return.
504 return NULL;
505 }
507 // for each entry in the directory that matches the pattern hsperfdata_*,
508 // open the directory and check if the file for the given vmid exists.
509 // The file with the expected name and the latest creation date is used
510 // to determine the user name for the process id.
511 //
512 struct dirent* dentry;
513 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
514 errno = 0;
515 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
517 // check if the directory entry is a hsperfdata file
518 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
519 continue;
520 }
522 char* usrdir_name = NEW_C_HEAP_ARRAY(char,
523 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
524 strcpy(usrdir_name, tmpdirname);
525 strcat(usrdir_name, "/");
526 strcat(usrdir_name, dentry->d_name);
528 // open the user directory
529 DIR* subdirp = open_directory_secure(usrdir_name);
531 if (subdirp == NULL) {
532 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
533 continue;
534 }
536 // Since we don't create the backing store files in directories
537 // pointed to by symbolic links, we also don't follow them when
538 // looking for the files. We check for a symbolic link after the
539 // call to opendir in order to eliminate a small window where the
540 // symlink can be exploited.
541 //
542 if (!is_directory_secure(usrdir_name)) {
543 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
544 os::closedir(subdirp);
545 continue;
546 }
548 struct dirent* udentry;
549 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
550 errno = 0;
551 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
553 if (filename_to_pid(udentry->d_name) == vmid) {
554 struct stat statbuf;
555 int result;
557 char* filename = NEW_C_HEAP_ARRAY(char,
558 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
560 strcpy(filename, usrdir_name);
561 strcat(filename, "/");
562 strcat(filename, udentry->d_name);
564 // don't follow symbolic links for the file
565 RESTARTABLE(::lstat(filename, &statbuf), result);
566 if (result == OS_ERR) {
567 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
568 continue;
569 }
571 // skip over files that are not regular files.
572 if (!S_ISREG(statbuf.st_mode)) {
573 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
574 continue;
575 }
577 // compare and save filename with latest creation time
578 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
580 if (statbuf.st_ctime > oldest_ctime) {
581 char* user = strchr(dentry->d_name, '_') + 1;
583 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user, mtInternal);
584 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal);
586 strcpy(oldest_user, user);
587 oldest_ctime = statbuf.st_ctime;
588 }
589 }
591 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
592 }
593 }
594 os::closedir(subdirp);
595 FREE_C_HEAP_ARRAY(char, udbuf, mtInternal);
596 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
597 }
598 os::closedir(tmpdirp);
599 FREE_C_HEAP_ARRAY(char, tdbuf, mtInternal);
601 return(oldest_user);
602 }
604 // return the name of the user that owns the JVM indicated by the given vmid.
605 //
606 static char* get_user_name(int vmid, TRAPS) {
608 char psinfo_name[PATH_MAX];
609 int result;
611 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid);
613 RESTARTABLE(::open(psinfo_name, O_RDONLY), result);
615 if (result != OS_ERR) {
616 int fd = result;
618 psinfo_t psinfo;
619 char* addr = (char*)&psinfo;
621 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) {
623 RESTARTABLE(::read(fd, addr, remaining), result);
624 if (result == OS_ERR) {
625 ::close(fd);
626 THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error");
627 } else {
628 remaining-=result;
629 addr+=result;
630 }
631 }
633 ::close(fd);
635 // get the user name for the effective user id of the process
636 char* user_name = get_user_name(psinfo.pr_euid);
638 return user_name;
639 }
641 if (result == OS_ERR && errno == EACCES) {
643 // In this case, the psinfo file for the process id existed,
644 // but we didn't have permission to access it.
645 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
646 strerror(errno));
647 }
649 // at this point, we don't know if the process id itself doesn't
650 // exist or if the psinfo file doesn't exit. If the psinfo file
651 // doesn't exist, then we are running on Solaris 2.5.1 or earlier.
652 // since the structured procfs and old procfs interfaces can't be
653 // mixed, we attempt to find the file through a directory search.
655 return get_user_name_slow(vmid, CHECK_NULL);
656 }
658 // return the file name of the backing store file for the named
659 // shared memory region for the given user name and vmid.
660 //
661 // the caller is expected to free the allocated memory.
662 //
663 static char* get_sharedmem_filename(const char* dirname, int vmid) {
665 // add 2 for the file separator and a NULL terminator.
666 size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
668 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
669 snprintf(name, nbytes, "%s/%d", dirname, vmid);
671 return name;
672 }
675 // remove file
676 //
677 // this method removes the file specified by the given path
678 //
679 static void remove_file(const char* path) {
681 int result;
683 // if the file is a directory, the following unlink will fail. since
684 // we don't expect to find directories in the user temp directory, we
685 // won't try to handle this situation. even if accidentially or
686 // maliciously planted, the directory's presence won't hurt anything.
687 //
688 RESTARTABLE(::unlink(path), result);
689 if (PrintMiscellaneous && Verbose && result == OS_ERR) {
690 if (errno != ENOENT) {
691 warning("Could not unlink shared memory backing"
692 " store file %s : %s\n", path, strerror(errno));
693 }
694 }
695 }
698 // cleanup stale shared memory resources
699 //
700 // This method attempts to remove all stale shared memory files in
701 // the named user temporary directory. It scans the named directory
702 // for files matching the pattern ^$[0-9]*$. For each file found, the
703 // process id is extracted from the file name and a test is run to
704 // determine if the process is alive. If the process is not alive,
705 // any stale file resources are removed.
706 //
707 static void cleanup_sharedmem_resources(const char* dirname) {
709 int saved_cwd_fd;
710 // open the directory
711 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
712 if (dirp == NULL) {
713 // directory doesn't exist or is insecure, so there is nothing to cleanup
714 return;
715 }
717 // for each entry in the directory that matches the expected file
718 // name pattern, determine if the file resources are stale and if
719 // so, remove the file resources. Note, instrumented HotSpot processes
720 // for this user may start and/or terminate during this search and
721 // remove or create new files in this directory. The behavior of this
722 // loop under these conditions is dependent upon the implementation of
723 // opendir/readdir.
724 //
725 struct dirent* entry;
726 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
728 errno = 0;
729 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
731 pid_t pid = filename_to_pid(entry->d_name);
733 if (pid == 0) {
735 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
737 // attempt to remove all unexpected files, except "." and ".."
738 unlink(entry->d_name);
739 }
741 errno = 0;
742 continue;
743 }
745 // we now have a file name that converts to a valid integer
746 // that could represent a process id . if this process id
747 // matches the current process id or the process is not running,
748 // then remove the stale file resources.
749 //
750 // process liveness is detected by sending signal number 0 to
751 // the process id (see kill(2)). if kill determines that the
752 // process does not exist, then the file resources are removed.
753 // if kill determines that that we don't have permission to
754 // signal the process, then the file resources are assumed to
755 // be stale and are removed because the resources for such a
756 // process should be in a different user specific directory.
757 //
758 if ((pid == os::current_process_id()) ||
759 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
761 unlink(entry->d_name);
762 }
763 errno = 0;
764 }
766 // close the directory and reset the current working directory
767 close_directory_secure_cwd(dirp, saved_cwd_fd);
769 FREE_C_HEAP_ARRAY(char, dbuf, mtInternal);
770 }
772 // make the user specific temporary directory. Returns true if
773 // the directory exists and is secure upon return. Returns false
774 // if the directory exists but is either a symlink, is otherwise
775 // insecure, or if an error occurred.
776 //
777 static bool make_user_tmp_dir(const char* dirname) {
779 // create the directory with 0755 permissions. note that the directory
780 // will be owned by euid::egid, which may not be the same as uid::gid.
781 //
782 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
783 if (errno == EEXIST) {
784 // The directory already exists and was probably created by another
785 // JVM instance. However, this could also be the result of a
786 // deliberate symlink. Verify that the existing directory is safe.
787 //
788 if (!is_directory_secure(dirname)) {
789 // directory is not secure
790 if (PrintMiscellaneous && Verbose) {
791 warning("%s directory is insecure\n", dirname);
792 }
793 return false;
794 }
795 }
796 else {
797 // we encountered some other failure while attempting
798 // to create the directory
799 //
800 if (PrintMiscellaneous && Verbose) {
801 warning("could not create directory %s: %s\n",
802 dirname, strerror(errno));
803 }
804 return false;
805 }
806 }
807 return true;
808 }
810 // create the shared memory file resources
811 //
812 // This method creates the shared memory file with the given size
813 // This method also creates the user specific temporary directory, if
814 // it does not yet exist.
815 //
816 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
818 // make the user temporary directory
819 if (!make_user_tmp_dir(dirname)) {
820 // could not make/find the directory or the found directory
821 // was not secure
822 return -1;
823 }
825 int saved_cwd_fd;
826 // open the directory and set the current working directory to it
827 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
828 if (dirp == NULL) {
829 // Directory doesn't exist or is insecure, so cannot create shared
830 // memory file.
831 return -1;
832 }
834 // Open the filename in the current directory.
835 // Cannot use O_TRUNC here; truncation of an existing file has to happen
836 // after the is_file_secure() check below.
837 int result;
838 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result);
839 if (result == OS_ERR) {
840 if (PrintMiscellaneous && Verbose) {
841 if (errno == ELOOP) {
842 warning("file %s is a symlink and is not secure\n", filename);
843 } else {
844 warning("could not create file %s: %s\n", filename, strerror(errno));
845 }
846 }
847 // close the directory and reset the current working directory
848 close_directory_secure_cwd(dirp, saved_cwd_fd);
850 return -1;
851 }
852 // close the directory and reset the current working directory
853 close_directory_secure_cwd(dirp, saved_cwd_fd);
855 // save the file descriptor
856 int fd = result;
858 // check to see if the file is secure
859 if (!is_file_secure(fd, filename)) {
860 ::close(fd);
861 return -1;
862 }
864 // truncate the file to get rid of any existing data
865 RESTARTABLE(::ftruncate(fd, (off_t)0), result);
866 if (result == OS_ERR) {
867 if (PrintMiscellaneous && Verbose) {
868 warning("could not truncate shared memory file: %s\n", strerror(errno));
869 }
870 ::close(fd);
871 return -1;
872 }
873 // set the file size
874 RESTARTABLE(::ftruncate(fd, (off_t)size), result);
875 if (result == OS_ERR) {
876 if (PrintMiscellaneous && Verbose) {
877 warning("could not set shared memory file size: %s\n", strerror(errno));
878 }
879 ::close(fd);
880 return -1;
881 }
883 return fd;
884 }
886 // open the shared memory file for the given user and vmid. returns
887 // the file descriptor for the open file or -1 if the file could not
888 // be opened.
889 //
890 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
892 // open the file
893 int result;
894 RESTARTABLE(::open(filename, oflags), result);
895 if (result == OS_ERR) {
896 if (errno == ENOENT) {
897 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
898 "Process not found", OS_ERR);
899 }
900 else if (errno == EACCES) {
901 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
902 "Permission denied", OS_ERR);
903 }
904 else {
905 THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR);
906 }
907 }
908 int fd = result;
910 // check to see if the file is secure
911 if (!is_file_secure(fd, filename)) {
912 ::close(fd);
913 return -1;
914 }
916 return fd;
917 }
919 // create a named shared memory region. returns the address of the
920 // memory region on success or NULL on failure. A return value of
921 // NULL will ultimately disable the shared memory feature.
922 //
923 // On Solaris and Linux, the name space for shared memory objects
924 // is the file system name space.
925 //
926 // A monitoring application attaching to a JVM does not need to know
927 // the file system name of the shared memory object. However, it may
928 // be convenient for applications to discover the existence of newly
929 // created and terminating JVMs by watching the file system name space
930 // for files being created or removed.
931 //
932 static char* mmap_create_shared(size_t size) {
934 int result;
935 int fd;
936 char* mapAddress;
938 int vmid = os::current_process_id();
940 char* user_name = get_user_name(geteuid());
942 if (user_name == NULL)
943 return NULL;
945 char* dirname = get_user_tmp_dir(user_name);
946 char* filename = get_sharedmem_filename(dirname, vmid);
948 // get the short filename
949 char* short_filename = strrchr(filename, '/');
950 if (short_filename == NULL) {
951 short_filename = filename;
952 } else {
953 short_filename++;
954 }
956 // cleanup any stale shared memory files
957 cleanup_sharedmem_resources(dirname);
959 assert(((size > 0) && (size % os::vm_page_size() == 0)),
960 "unexpected PerfMemory region size");
962 fd = create_sharedmem_resources(dirname, short_filename, size);
964 FREE_C_HEAP_ARRAY(char, user_name, mtInternal);
965 FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
967 if (fd == -1) {
968 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
969 return NULL;
970 }
972 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
974 result = ::close(fd);
975 assert(result != OS_ERR, "could not close file");
977 if (mapAddress == MAP_FAILED) {
978 if (PrintMiscellaneous && Verbose) {
979 warning("mmap failed - %s\n", strerror(errno));
980 }
981 remove_file(filename);
982 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
983 return NULL;
984 }
986 // save the file name for use in delete_shared_memory()
987 backing_store_file_name = filename;
989 // clear the shared memory region
990 (void)::memset((void*) mapAddress, 0, size);
992 // it does not go through os api, the operation has to record from here
993 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress,
994 size, CURRENT_PC, mtInternal);
996 return mapAddress;
997 }
999 // release a named shared memory region
1000 //
1001 static void unmap_shared(char* addr, size_t bytes) {
1002 os::release_memory(addr, bytes);
1003 }
1005 // create the PerfData memory region in shared memory.
1006 //
1007 static char* create_shared_memory(size_t size) {
1009 // create the shared memory region.
1010 return mmap_create_shared(size);
1011 }
1013 // delete the shared PerfData memory region
1014 //
1015 static void delete_shared_memory(char* addr, size_t size) {
1017 // cleanup the persistent shared memory resources. since DestroyJavaVM does
1018 // not support unloading of the JVM, unmapping of the memory resource is
1019 // not performed. The memory will be reclaimed by the OS upon termination of
1020 // the process. The backing store file is deleted from the file system.
1022 assert(!PerfDisableSharedMem, "shouldn't be here");
1024 if (backing_store_file_name != NULL) {
1025 remove_file(backing_store_file_name);
1026 // Don't.. Free heap memory could deadlock os::abort() if it is called
1027 // from signal handler. OS will reclaim the heap memory.
1028 // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
1029 backing_store_file_name = NULL;
1030 }
1031 }
1033 // return the size of the file for the given file descriptor
1034 // or 0 if it is not a valid size for a shared memory file
1035 //
1036 static size_t sharedmem_filesize(int fd, TRAPS) {
1038 struct stat statbuf;
1039 int result;
1041 RESTARTABLE(::fstat(fd, &statbuf), result);
1042 if (result == OS_ERR) {
1043 if (PrintMiscellaneous && Verbose) {
1044 warning("fstat failed: %s\n", strerror(errno));
1045 }
1046 THROW_MSG_0(vmSymbols::java_io_IOException(),
1047 "Could not determine PerfMemory size");
1048 }
1050 if ((statbuf.st_size == 0) ||
1051 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
1052 THROW_MSG_0(vmSymbols::java_lang_Exception(),
1053 "Invalid PerfMemory size");
1054 }
1056 return (size_t)statbuf.st_size;
1057 }
1059 // attach to a named shared memory region.
1060 //
1061 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
1063 char* mapAddress;
1064 int result;
1065 int fd;
1066 size_t size = 0;
1067 const char* luser = NULL;
1069 int mmap_prot;
1070 int file_flags;
1072 ResourceMark rm;
1074 // map the high level access mode to the appropriate permission
1075 // constructs for the file and the shared memory mapping.
1076 if (mode == PerfMemory::PERF_MODE_RO) {
1077 mmap_prot = PROT_READ;
1078 file_flags = O_RDONLY | O_NOFOLLOW;
1079 }
1080 else if (mode == PerfMemory::PERF_MODE_RW) {
1081 #ifdef LATER
1082 mmap_prot = PROT_READ | PROT_WRITE;
1083 file_flags = O_RDWR | O_NOFOLLOW;
1084 #else
1085 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1086 "Unsupported access mode");
1087 #endif
1088 }
1089 else {
1090 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1091 "Illegal access mode");
1092 }
1094 if (user == NULL || strlen(user) == 0) {
1095 luser = get_user_name(vmid, CHECK);
1096 }
1097 else {
1098 luser = user;
1099 }
1101 if (luser == NULL) {
1102 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1103 "Could not map vmid to user Name");
1104 }
1106 char* dirname = get_user_tmp_dir(luser);
1108 // since we don't follow symbolic links when creating the backing
1109 // store file, we don't follow them when attaching either.
1110 //
1111 if (!is_directory_secure(dirname)) {
1112 FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
1113 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1114 "Process not found");
1115 }
1117 char* filename = get_sharedmem_filename(dirname, vmid);
1119 // copy heap memory to resource memory. the open_sharedmem_file
1120 // method below need to use the filename, but could throw an
1121 // exception. using a resource array prevents the leak that
1122 // would otherwise occur.
1123 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
1124 strcpy(rfilename, filename);
1126 // free the c heap resources that are no longer needed
1127 if (luser != user) FREE_C_HEAP_ARRAY(char, luser, mtInternal);
1128 FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
1129 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
1131 // open the shared memory file for the give vmid
1132 fd = open_sharedmem_file(rfilename, file_flags, THREAD);
1134 if (fd == OS_ERR) {
1135 return;
1136 }
1138 if (HAS_PENDING_EXCEPTION) {
1139 ::close(fd);
1140 return;
1141 }
1143 if (*sizep == 0) {
1144 size = sharedmem_filesize(fd, CHECK);
1145 } else {
1146 size = *sizep;
1147 }
1149 assert(size > 0, "unexpected size <= 0");
1151 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
1153 result = ::close(fd);
1154 assert(result != OS_ERR, "could not close file");
1156 if (mapAddress == MAP_FAILED) {
1157 if (PrintMiscellaneous && Verbose) {
1158 warning("mmap failed: %s\n", strerror(errno));
1159 }
1160 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
1161 "Could not map PerfMemory");
1162 }
1164 // it does not go through os api, the operation has to record from here
1165 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress,
1166 size, CURRENT_PC, mtInternal);
1168 *addr = mapAddress;
1169 *sizep = size;
1171 if (PerfTraceMemOps) {
1172 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
1173 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress);
1174 }
1175 }
1180 // create the PerfData memory region
1181 //
1182 // This method creates the memory region used to store performance
1183 // data for the JVM. The memory may be created in standard or
1184 // shared memory.
1185 //
1186 void PerfMemory::create_memory_region(size_t size) {
1188 if (PerfDisableSharedMem) {
1189 // do not share the memory for the performance data.
1190 _start = create_standard_memory(size);
1191 }
1192 else {
1193 _start = create_shared_memory(size);
1194 if (_start == NULL) {
1196 // creation of the shared memory region failed, attempt
1197 // to create a contiguous, non-shared memory region instead.
1198 //
1199 if (PrintMiscellaneous && Verbose) {
1200 warning("Reverting to non-shared PerfMemory region.\n");
1201 }
1202 PerfDisableSharedMem = true;
1203 _start = create_standard_memory(size);
1204 }
1205 }
1207 if (_start != NULL) _capacity = size;
1209 }
1211 // delete the PerfData memory region
1212 //
1213 // This method deletes the memory region used to store performance
1214 // data for the JVM. The memory region indicated by the <address, size>
1215 // tuple will be inaccessible after a call to this method.
1216 //
1217 void PerfMemory::delete_memory_region() {
1219 assert((start() != NULL && capacity() > 0), "verify proper state");
1221 // If user specifies PerfDataSaveFile, it will save the performance data
1222 // to the specified file name no matter whether PerfDataSaveToFile is specified
1223 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
1224 // -XX:+PerfDataSaveToFile.
1225 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
1226 save_memory_to_file(start(), capacity());
1227 }
1229 if (PerfDisableSharedMem) {
1230 delete_standard_memory(start(), capacity());
1231 }
1232 else {
1233 delete_shared_memory(start(), capacity());
1234 }
1235 }
1237 // attach to the PerfData memory region for another JVM
1238 //
1239 // This method returns an <address, size> tuple that points to
1240 // a memory buffer that is kept reasonably synchronized with
1241 // the PerfData memory region for the indicated JVM. This
1242 // buffer may be kept in synchronization via shared memory
1243 // or some other mechanism that keeps the buffer updated.
1244 //
1245 // If the JVM chooses not to support the attachability feature,
1246 // this method should throw an UnsupportedOperation exception.
1247 //
1248 // This implementation utilizes named shared memory to map
1249 // the indicated process's PerfData memory region into this JVMs
1250 // address space.
1251 //
1252 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
1254 if (vmid == 0 || vmid == os::current_process_id()) {
1255 *addrp = start();
1256 *sizep = capacity();
1257 return;
1258 }
1260 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
1261 }
1263 // detach from the PerfData memory region of another JVM
1264 //
1265 // This method detaches the PerfData memory region of another
1266 // JVM, specified as an <address, size> tuple of a buffer
1267 // in this process's address space. This method may perform
1268 // arbitrary actions to accomplish the detachment. The memory
1269 // region specified by <address, size> will be inaccessible after
1270 // a call to this method.
1271 //
1272 // If the JVM chooses not to support the attachability feature,
1273 // this method should throw an UnsupportedOperation exception.
1274 //
1275 // This implementation utilizes named shared memory to detach
1276 // the indicated process's PerfData memory region from this
1277 // process's address space.
1278 //
1279 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1281 assert(addr != 0, "address sanity check");
1282 assert(bytes > 0, "capacity sanity check");
1284 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1285 // prevent accidental detachment of this process's PerfMemory region
1286 return;
1287 }
1289 unmap_shared(addr, bytes);
1290 }
1292 char* PerfMemory::backing_store_filename() {
1293 return backing_store_file_name;
1294 }