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 */
24
25 #include "precompiled.hpp"
26 #include "classfile/vmSymbols.hpp"
27 #include "memory/allocation.inline.hpp"
28 #include "memory/resourceArea.hpp"
29 #include "oops/oop.inline.hpp"
30 #include "os_bsd.inline.hpp"
31 #include "runtime/handles.inline.hpp"
32 #include "runtime/perfMemory.hpp"
33 #include "services/memTracker.hpp"
34 #include "utilities/exceptions.hpp"
35
36 // put OS-includes here
37 # include <sys/types.h>
38 # include <sys/mman.h>
39 # include <errno.h>
40 # include <stdio.h>
41 # include <unistd.h>
42 # include <sys/stat.h>
43 # include <signal.h>
44 # include <pwd.h>
45
46 static char* backing_store_file_name = NULL; // name of the backing store
47 // file, if successfully created.
48
49 // Standard Memory Implementation Details
50
51 // create the PerfData memory region in standard memory.
52 //
53 static char* create_standard_memory(size_t size) {
54
55 // allocate an aligned chuck of memory
56 char* mapAddress = os::reserve_memory(size);
57
58 if (mapAddress == NULL) {
59 return NULL;
60 }
61
62 // commit memory
63 if (!os::commit_memory(mapAddress, size, !ExecMem)) {
64 if (PrintMiscellaneous && Verbose) {
65 warning("Could not commit PerfData memory\n");
66 }
67 os::release_memory(mapAddress, size);
68 return NULL;
69 }
70
71 return mapAddress;
72 }
73
74 // delete the PerfData memory region
75 //
76 static void delete_standard_memory(char* addr, size_t size) {
77
78 // there are no persistent external resources to cleanup for standard
79 // memory. since DestroyJavaVM does not support unloading of the JVM,
80 // cleanup of the memory resource is not performed. The memory will be
81 // reclaimed by the OS upon termination of the process.
82 //
83 return;
84 }
85
86 // save the specified memory region to the given file
87 //
88 // Note: this function might be called from signal handler (by os::abort()),
89 // don't allocate heap memory.
90 //
91 static void save_memory_to_file(char* addr, size_t size) {
92
93 const char* destfile = PerfMemory::get_perfdata_file_path();
94 assert(destfile[0] != '\0', "invalid PerfData file path");
95
96 int result;
97
98 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE),
99 result);;
100 if (result == OS_ERR) {
101 if (PrintMiscellaneous && Verbose) {
102 warning("Could not create Perfdata save file: %s: %s\n",
103 destfile, strerror(errno));
104 }
105 } else {
106 int fd = result;
107
108 for (size_t remaining = size; remaining > 0;) {
109
110 RESTARTABLE(::write(fd, addr, remaining), result);
111 if (result == OS_ERR) {
112 if (PrintMiscellaneous && Verbose) {
113 warning("Could not write Perfdata save file: %s: %s\n",
114 destfile, strerror(errno));
115 }
116 break;
117 }
118
119 remaining -= (size_t)result;
120 addr += result;
121 }
122
123 result = ::close(fd);
124 if (PrintMiscellaneous && Verbose) {
125 if (result == OS_ERR) {
126 warning("Could not close %s: %s\n", destfile, strerror(errno));
127 }
128 }
129 }
130 FREE_C_HEAP_ARRAY(char, destfile);
131 }
132
133
134 // Shared Memory Implementation Details
135
136 // Note: the solaris and bsd shared memory implementation uses the mmap
137 // interface with a backing store file to implement named shared memory.
138 // Using the file system as the name space for shared memory allows a
139 // common name space to be supported across a variety of platforms. It
140 // also provides a name space that Java applications can deal with through
141 // simple file apis.
142 //
143 // The solaris and bsd implementations store the backing store file in
144 // a user specific temporary directory located in the /tmp file system,
145 // which is always a local file system and is sometimes a RAM based file
146 // system.
147
148 // return the user specific temporary directory name.
149 //
150 // the caller is expected to free the allocated memory.
151 //
152 static char* get_user_tmp_dir(const char* user) {
153
154 const char* tmpdir = os::get_temp_directory();
155 const char* perfdir = PERFDATA_NAME;
156 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3;
157 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
158
159 // construct the path name to user specific tmp directory
160 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user);
161
162 return dirname;
163 }
164
165 // convert the given file name into a process id. if the file
166 // does not meet the file naming constraints, return 0.
167 //
168 static pid_t filename_to_pid(const char* filename) {
169
170 // a filename that doesn't begin with a digit is not a
171 // candidate for conversion.
172 //
173 if (!isdigit(*filename)) {
174 return 0;
175 }
176
177 // check if file name can be converted to an integer without
178 // any leftover characters.
179 //
180 char* remainder = NULL;
181 errno = 0;
182 pid_t pid = (pid_t)strtol(filename, &remainder, 10);
183
184 if (errno != 0) {
185 return 0;
186 }
187
188 // check for left over characters. If any, then the filename is
189 // not a candidate for conversion.
190 //
191 if (remainder != NULL && *remainder != '\0') {
192 return 0;
193 }
194
195 // successful conversion, return the pid
196 return pid;
197 }
198
199
200 // Check if the given statbuf is considered a secure directory for
201 // the backing store files. Returns true if the directory is considered
202 // a secure location. Returns false if the statbuf is a symbolic link or
203 // if an error occurred.
204 //
205 static bool is_statbuf_secure(struct stat *statp) {
206 if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) {
207 // The path represents a link or some non-directory file type,
208 // which is not what we expected. Declare it insecure.
209 //
210 return false;
211 }
212 // We have an existing directory, check if the permissions are safe.
213 //
214 if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) {
215 // The directory is open for writing and could be subjected
216 // to a symlink or a hard link attack. Declare it insecure.
217 //
218 return false;
219 }
220 // See if the uid of the directory matches the effective uid of the process.
221 //
222 if (statp->st_uid != geteuid()) {
223 // The directory was not created by this user, declare it insecure.
224 //
225 return false;
226 }
227 return true;
228 }
229
230
231 // Check if the given path is considered a secure directory for
232 // the backing store files. Returns true if the directory exists
233 // and is considered a secure location. Returns false if the path
234 // is a symbolic link or if an error occurred.
235 //
236 static bool is_directory_secure(const char* path) {
237 struct stat statbuf;
238 int result = 0;
239
240 RESTARTABLE(::lstat(path, &statbuf), result);
241 if (result == OS_ERR) {
242 return false;
243 }
244
245 // The path exists, see if it is secure.
246 return is_statbuf_secure(&statbuf);
247 }
248
249
250 // Check if the given directory file descriptor is considered a secure
251 // directory for the backing store files. Returns true if the directory
252 // exists and is considered a secure location. Returns false if the path
253 // is a symbolic link or if an error occurred.
254 //
255 static bool is_dirfd_secure(int dir_fd) {
256 struct stat statbuf;
257 int result = 0;
258
259 RESTARTABLE(::fstat(dir_fd, &statbuf), result);
260 if (result == OS_ERR) {
261 return false;
262 }
263
264 // The path exists, now check its mode.
265 return is_statbuf_secure(&statbuf);
266 }
267
268
269 // Check to make sure fd1 and fd2 are referencing the same file system object.
270 //
271 static bool is_same_fsobject(int fd1, int fd2) {
272 struct stat statbuf1;
273 struct stat statbuf2;
274 int result = 0;
275
276 RESTARTABLE(::fstat(fd1, &statbuf1), result);
277 if (result == OS_ERR) {
278 return false;
279 }
280 RESTARTABLE(::fstat(fd2, &statbuf2), result);
281 if (result == OS_ERR) {
282 return false;
283 }
284
285 if ((statbuf1.st_ino == statbuf2.st_ino) &&
286 (statbuf1.st_dev == statbuf2.st_dev)) {
287 return true;
288 } else {
289 return false;
290 }
291 }
292
293
294 // Open the directory of the given path and validate it.
295 // Return a DIR * of the open directory.
296 //
297 static DIR *open_directory_secure(const char* dirname) {
298 // Open the directory using open() so that it can be verified
299 // to be secure by calling is_dirfd_secure(), opendir() and then check
300 // to see if they are the same file system object. This method does not
301 // introduce a window of opportunity for the directory to be attacked that
302 // calling opendir() and is_directory_secure() does.
303 int result;
304 DIR *dirp = NULL;
305 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result);
306 if (result == OS_ERR) {
307 // Directory doesn't exist or is a symlink, so there is nothing to cleanup.
308 if (PrintMiscellaneous && Verbose) {
309 if (errno == ELOOP) {
310 warning("directory %s is a symlink and is not secure\n", dirname);
311 } else {
312 warning("could not open directory %s: %s\n", dirname, strerror(errno));
313 }
314 }
315 return dirp;
316 }
317 int fd = result;
318
319 // Determine if the open directory is secure.
320 if (!is_dirfd_secure(fd)) {
321 // The directory is not a secure directory.
322 os::close(fd);
323 return dirp;
324 }
325
326 // Open the directory.
327 dirp = ::opendir(dirname);
328 if (dirp == NULL) {
329 // The directory doesn't exist, close fd and return.
330 os::close(fd);
331 return dirp;
332 }
333
334 // Check to make sure fd and dirp are referencing the same file system object.
335 if (!is_same_fsobject(fd, dirfd(dirp))) {
336 // The directory is not secure.
337 os::close(fd);
338 os::closedir(dirp);
339 dirp = NULL;
340 return dirp;
341 }
342
343 // Close initial open now that we know directory is secure
344 os::close(fd);
345
346 return dirp;
347 }
348
349 // NOTE: The code below uses fchdir(), open() and unlink() because
350 // fdopendir(), openat() and unlinkat() are not supported on all
351 // versions. Once the support for fdopendir(), openat() and unlinkat()
352 // is available on all supported versions the code can be changed
353 // to use these functions.
354
355 // Open the directory of the given path, validate it and set the
356 // current working directory to it.
357 // Return a DIR * of the open directory and the saved cwd fd.
358 //
359 static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) {
360
361 // Open the directory.
362 DIR* dirp = open_directory_secure(dirname);
363 if (dirp == NULL) {
364 // Directory doesn't exist or is insecure, so there is nothing to cleanup.
365 return dirp;
366 }
367 int fd = dirfd(dirp);
368
369 // Open a fd to the cwd and save it off.
370 int result;
371 RESTARTABLE(::open(".", O_RDONLY), result);
372 if (result == OS_ERR) {
373 *saved_cwd_fd = -1;
374 } else {
375 *saved_cwd_fd = result;
376 }
377
378 // Set the current directory to dirname by using the fd of the directory.
379 result = fchdir(fd);
380
381 return dirp;
382 }
383
384 // Close the directory and restore the current working directory.
385 //
386 static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) {
387
388 int result;
389 // If we have a saved cwd change back to it and close the fd.
390 if (saved_cwd_fd != -1) {
391 result = fchdir(saved_cwd_fd);
392 ::close(saved_cwd_fd);
393 }
394
395 // Close the directory.
396 os::closedir(dirp);
397 }
398
399 // Check if the given file descriptor is considered a secure.
400 //
401 static bool is_file_secure(int fd, const char *filename) {
402
403 int result;
404 struct stat statbuf;
405
406 // Determine if the file is secure.
407 RESTARTABLE(::fstat(fd, &statbuf), result);
408 if (result == OS_ERR) {
409 if (PrintMiscellaneous && Verbose) {
410 warning("fstat failed on %s: %s\n", filename, strerror(errno));
411 }
412 return false;
413 }
414 if (statbuf.st_nlink > 1) {
415 // A file with multiple links is not expected.
416 if (PrintMiscellaneous && Verbose) {
417 warning("file %s has multiple links\n", filename);
418 }
419 return false;
420 }
421 return true;
422 }
423
424 // return the user name for the given user id
425 //
426 // the caller is expected to free the allocated memory.
427 //
428 static char* get_user_name(uid_t uid) {
429
430 struct passwd pwent;
431
432 // determine the max pwbuf size from sysconf, and hardcode
433 // a default if this not available through sysconf.
434 //
435 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
436 if (bufsize == -1)
437 bufsize = 1024;
438
439 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
440
441 // POSIX interface to getpwuid_r is used on LINUX
442 struct passwd* p;
443 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);
444
445 if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {
446 if (PrintMiscellaneous && Verbose) {
447 if (result != 0) {
448 warning("Could not retrieve passwd entry: %s\n",
449 strerror(result));
450 }
451 else if (p == NULL) {
452 // this check is added to protect against an observed problem
453 // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0,
454 // indicating success, but has p == NULL. This was observed when
455 // inserting a file descriptor exhaustion fault prior to the call
456 // getpwuid_r() call. In this case, error is set to the appropriate
457 // error condition, but this is undocumented behavior. This check
458 // is safe under any condition, but the use of errno in the output
459 // message may result in an erroneous message.
460 // Bug Id 89052 was opened with RedHat.
461 //
462 warning("Could not retrieve passwd entry: %s\n",
463 strerror(errno));
464 }
465 else {
466 warning("Could not determine user name: %s\n",
467 p->pw_name == NULL ? "pw_name = NULL" :
468 "pw_name zero length");
469 }
470 }
471 FREE_C_HEAP_ARRAY(char, pwbuf);
472 return NULL;
473 }
474
475 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal);
476 strcpy(user_name, p->pw_name);
477
478 FREE_C_HEAP_ARRAY(char, pwbuf);
479 return user_name;
480 }
481
482 // return the name of the user that owns the process identified by vmid.
483 //
484 // This method uses a slow directory search algorithm to find the backing
485 // store file for the specified vmid and returns the user name, as determined
486 // by the user name suffix of the hsperfdata_<username> directory name.
487 //
488 // the caller is expected to free the allocated memory.
489 //
490 static char* get_user_name_slow(int vmid, TRAPS) {
491
492 // short circuit the directory search if the process doesn't even exist.
493 if (kill(vmid, 0) == OS_ERR) {
494 if (errno == ESRCH) {
495 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
496 "Process not found");
497 }
498 else /* EPERM */ {
499 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));
500 }
501 }
502
503 // directory search
504 char* oldest_user = NULL;
505 time_t oldest_ctime = 0;
506
507 const char* tmpdirname = os::get_temp_directory();
508
509 // open the temp directory
510 DIR* tmpdirp = os::opendir(tmpdirname);
511
512 if (tmpdirp == NULL) {
513 // Cannot open the directory to get the user name, return.
514 return NULL;
515 }
516
517 // for each entry in the directory that matches the pattern hsperfdata_*,
518 // open the directory and check if the file for the given vmid exists.
519 // The file with the expected name and the latest creation date is used
520 // to determine the user name for the process id.
521 //
522 struct dirent* dentry;
523 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
524 errno = 0;
525 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
526
527 // check if the directory entry is a hsperfdata file
528 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
529 continue;
530 }
531
532 char* usrdir_name = NEW_C_HEAP_ARRAY(char,
533 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
534 strcpy(usrdir_name, tmpdirname);
535 strcat(usrdir_name, "/");
536 strcat(usrdir_name, dentry->d_name);
537
538 // open the user directory
539 DIR* subdirp = open_directory_secure(usrdir_name);
540
541 if (subdirp == NULL) {
542 FREE_C_HEAP_ARRAY(char, usrdir_name);
543 continue;
544 }
545
546 struct dirent* udentry;
547 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
548 errno = 0;
549 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
550
551 if (filename_to_pid(udentry->d_name) == vmid) {
552 struct stat statbuf;
553 int result;
554
555 char* filename = NEW_C_HEAP_ARRAY(char,
556 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
557
558 strcpy(filename, usrdir_name);
559 strcat(filename, "/");
560 strcat(filename, udentry->d_name);
561
562 // don't follow symbolic links for the file
563 RESTARTABLE(::lstat(filename, &statbuf), result);
564 if (result == OS_ERR) {
565 FREE_C_HEAP_ARRAY(char, filename);
566 continue;
567 }
568
569 // skip over files that are not regular files.
570 if (!S_ISREG(statbuf.st_mode)) {
571 FREE_C_HEAP_ARRAY(char, filename);
572 continue;
573 }
574
575 // compare and save filename with latest creation time
576 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
577
578 if (statbuf.st_ctime > oldest_ctime) {
579 char* user = strchr(dentry->d_name, '_') + 1;
580
581 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user);
582 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal);
583
584 strcpy(oldest_user, user);
585 oldest_ctime = statbuf.st_ctime;
586 }
587 }
588
589 FREE_C_HEAP_ARRAY(char, filename);
590 }
591 }
592 os::closedir(subdirp);
593 FREE_C_HEAP_ARRAY(char, udbuf);
594 FREE_C_HEAP_ARRAY(char, usrdir_name);
595 }
596 os::closedir(tmpdirp);
597 FREE_C_HEAP_ARRAY(char, tdbuf);
598
599 return(oldest_user);
600 }
601
602 // return the name of the user that owns the JVM indicated by the given vmid.
603 //
604 static char* get_user_name(int vmid, TRAPS) {
605 return get_user_name_slow(vmid, THREAD);
606 }
607
608 // return the file name of the backing store file for the named
609 // shared memory region for the given user name and vmid.
610 //
611 // the caller is expected to free the allocated memory.
612 //
613 static char* get_sharedmem_filename(const char* dirname, int vmid) {
614
615 // add 2 for the file separator and a null terminator.
616 size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
617
618 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
619 snprintf(name, nbytes, "%s/%d", dirname, vmid);
620
621 return name;
622 }
623
624
625 // remove file
626 //
627 // this method removes the file specified by the given path
628 //
629 static void remove_file(const char* path) {
630
631 int result;
632
633 // if the file is a directory, the following unlink will fail. since
634 // we don't expect to find directories in the user temp directory, we
635 // won't try to handle this situation. even if accidentially or
636 // maliciously planted, the directory's presence won't hurt anything.
637 //
638 RESTARTABLE(::unlink(path), result);
639 if (PrintMiscellaneous && Verbose && result == OS_ERR) {
640 if (errno != ENOENT) {
641 warning("Could not unlink shared memory backing"
642 " store file %s : %s\n", path, strerror(errno));
643 }
644 }
645 }
646
647
648 // cleanup stale shared memory resources
649 //
650 // This method attempts to remove all stale shared memory files in
651 // the named user temporary directory. It scans the named directory
652 // for files matching the pattern ^$[0-9]*$. For each file found, the
653 // process id is extracted from the file name and a test is run to
654 // determine if the process is alive. If the process is not alive,
655 // any stale file resources are removed.
656 //
657 static void cleanup_sharedmem_resources(const char* dirname) {
658
659 int saved_cwd_fd;
660 // open the directory and set the current working directory to it
661 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
662 if (dirp == NULL) {
663 // directory doesn't exist or is insecure, so there is nothing to cleanup
664 return;
665 }
666
667 // for each entry in the directory that matches the expected file
668 // name pattern, determine if the file resources are stale and if
669 // so, remove the file resources. Note, instrumented HotSpot processes
670 // for this user may start and/or terminate during this search and
671 // remove or create new files in this directory. The behavior of this
672 // loop under these conditions is dependent upon the implementation of
673 // opendir/readdir.
674 //
675 struct dirent* entry;
676 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
677
678 errno = 0;
679 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
680
681 pid_t pid = filename_to_pid(entry->d_name);
682
683 if (pid == 0) {
684
685 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
686
687 // attempt to remove all unexpected files, except "." and ".."
688 unlink(entry->d_name);
689 }
690
691 errno = 0;
692 continue;
693 }
694
695 // we now have a file name that converts to a valid integer
696 // that could represent a process id . if this process id
697 // matches the current process id or the process is not running,
698 // then remove the stale file resources.
699 //
700 // process liveness is detected by sending signal number 0 to
701 // the process id (see kill(2)). if kill determines that the
702 // process does not exist, then the file resources are removed.
703 // if kill determines that that we don't have permission to
704 // signal the process, then the file resources are assumed to
705 // be stale and are removed because the resources for such a
706 // process should be in a different user specific directory.
707 //
708 if ((pid == os::current_process_id()) ||
709 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
710
711 unlink(entry->d_name);
712 }
713 errno = 0;
714 }
715
716 // close the directory and reset the current working directory
717 close_directory_secure_cwd(dirp, saved_cwd_fd);
718
719 FREE_C_HEAP_ARRAY(char, dbuf);
720 }
721
722 // make the user specific temporary directory. Returns true if
723 // the directory exists and is secure upon return. Returns false
724 // if the directory exists but is either a symlink, is otherwise
725 // insecure, or if an error occurred.
726 //
727 static bool make_user_tmp_dir(const char* dirname) {
728
729 // create the directory with 0755 permissions. note that the directory
730 // will be owned by euid::egid, which may not be the same as uid::gid.
731 //
732 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
733 if (errno == EEXIST) {
734 // The directory already exists and was probably created by another
735 // JVM instance. However, this could also be the result of a
736 // deliberate symlink. Verify that the existing directory is safe.
737 //
738 if (!is_directory_secure(dirname)) {
739 // directory is not secure
740 if (PrintMiscellaneous && Verbose) {
741 warning("%s directory is insecure\n", dirname);
742 }
743 return false;
744 }
745 }
746 else {
747 // we encountered some other failure while attempting
748 // to create the directory
749 //
750 if (PrintMiscellaneous && Verbose) {
751 warning("could not create directory %s: %s\n",
752 dirname, strerror(errno));
753 }
754 return false;
755 }
756 }
757 return true;
758 }
759
760 // create the shared memory file resources
761 //
762 // This method creates the shared memory file with the given size
763 // This method also creates the user specific temporary directory, if
764 // it does not yet exist.
765 //
766 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
767
768 // make the user temporary directory
769 if (!make_user_tmp_dir(dirname)) {
770 // could not make/find the directory or the found directory
771 // was not secure
772 return -1;
773 }
774
775 int saved_cwd_fd;
776 // open the directory and set the current working directory to it
777 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
778 if (dirp == NULL) {
779 // Directory doesn't exist or is insecure, so cannot create shared
780 // memory file.
781 return -1;
782 }
783
784 // Open the filename in the current directory.
785 // Cannot use O_TRUNC here; truncation of an existing file has to happen
786 // after the is_file_secure() check below.
787 int result;
788 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result);
789 if (result == OS_ERR) {
790 if (PrintMiscellaneous && Verbose) {
791 if (errno == ELOOP) {
792 warning("file %s is a symlink and is not secure\n", filename);
793 } else {
794 warning("could not create file %s: %s\n", filename, strerror(errno));
795 }
796 }
797 // close the directory and reset the current working directory
798 close_directory_secure_cwd(dirp, saved_cwd_fd);
799
800 return -1;
801 }
802 // close the directory and reset the current working directory
803 close_directory_secure_cwd(dirp, saved_cwd_fd);
804
805 // save the file descriptor
806 int fd = result;
807
808 // check to see if the file is secure
809 if (!is_file_secure(fd, filename)) {
810 ::close(fd);
811 return -1;
812 }
813
814 // truncate the file to get rid of any existing data
815 RESTARTABLE(::ftruncate(fd, (off_t)0), result);
816 if (result == OS_ERR) {
817 if (PrintMiscellaneous && Verbose) {
818 warning("could not truncate shared memory file: %s\n", strerror(errno));
819 }
820 ::close(fd);
821 return -1;
822 }
823 // set the file size
824 RESTARTABLE(::ftruncate(fd, (off_t)size), result);
825 if (result == OS_ERR) {
826 if (PrintMiscellaneous && Verbose) {
827 warning("could not set shared memory file size: %s\n", strerror(errno));
828 }
829 ::close(fd);
830 return -1;
831 }
832
833 // Verify that we have enough disk space for this file.
834 // We'll get random SIGBUS crashes on memory accesses if
835 // we don't.
836
837 for (size_t seekpos = 0; seekpos < size; seekpos += os::vm_page_size()) {
838 int zero_int = 0;
839 result = (int)os::seek_to_file_offset(fd, (jlong)(seekpos));
840 if (result == -1 ) break;
841 RESTARTABLE(::write(fd, &zero_int, 1), result);
842 if (result != 1) {
843 if (errno == ENOSPC) {
844 warning("Insufficient space for shared memory file:\n %s\nTry using the -Djava.io.tmpdir= option to select an alternate temp location.\n", filename);
845 }
846 break;
847 }
848 }
849
850 if (result != -1) {
851 return fd;
852 } else {
853 ::close(fd);
854 return -1;
855 }
856 }
857
858 // open the shared memory file for the given user and vmid. returns
859 // the file descriptor for the open file or -1 if the file could not
860 // be opened.
861 //
862 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
863
864 // open the file
865 int result;
866 RESTARTABLE(::open(filename, oflags), result);
867 if (result == OS_ERR) {
868 if (errno == ENOENT) {
869 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
870 "Process not found", OS_ERR);
871 }
872 else if (errno == EACCES) {
873 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
874 "Permission denied", OS_ERR);
875 }
876 else {
877 THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR);
878 }
879 }
880 int fd = result;
881
882 // check to see if the file is secure
883 if (!is_file_secure(fd, filename)) {
884 ::close(fd);
885 return -1;
886 }
887
888 return fd;
889 }
890
891 // create a named shared memory region. returns the address of the
892 // memory region on success or NULL on failure. A return value of
893 // NULL will ultimately disable the shared memory feature.
894 //
895 // On Solaris and Bsd, the name space for shared memory objects
896 // is the file system name space.
897 //
898 // A monitoring application attaching to a JVM does not need to know
899 // the file system name of the shared memory object. However, it may
900 // be convenient for applications to discover the existence of newly
901 // created and terminating JVMs by watching the file system name space
902 // for files being created or removed.
903 //
904 static char* mmap_create_shared(size_t size) {
905
906 int result;
907 int fd;
908 char* mapAddress;
909
910 int vmid = os::current_process_id();
911
912 char* user_name = get_user_name(geteuid());
913
914 if (user_name == NULL)
915 return NULL;
916
917 char* dirname = get_user_tmp_dir(user_name);
918 char* filename = get_sharedmem_filename(dirname, vmid);
919
920 // get the short filename
921 char* short_filename = strrchr(filename, '/');
922 if (short_filename == NULL) {
923 short_filename = filename;
924 } else {
925 short_filename++;
926 }
927
928 // cleanup any stale shared memory files
929 cleanup_sharedmem_resources(dirname);
930
931 assert(((size > 0) && (size % os::vm_page_size() == 0)),
932 "unexpected PerfMemory region size");
933
934 fd = create_sharedmem_resources(dirname, short_filename, size);
935
936 FREE_C_HEAP_ARRAY(char, user_name);
937 FREE_C_HEAP_ARRAY(char, dirname);
938
939 if (fd == -1) {
940 FREE_C_HEAP_ARRAY(char, filename);
941 return NULL;
942 }
943
944 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
945
946 result = ::close(fd);
947 assert(result != OS_ERR, "could not close file");
948
949 if (mapAddress == MAP_FAILED) {
950 if (PrintMiscellaneous && Verbose) {
951 warning("mmap failed - %s\n", strerror(errno));
952 }
953 remove_file(filename);
954 FREE_C_HEAP_ARRAY(char, filename);
955 return NULL;
956 }
957
958 // save the file name for use in delete_shared_memory()
959 backing_store_file_name = filename;
960
961 // clear the shared memory region
962 (void)::memset((void*) mapAddress, 0, size);
963
964 // it does not go through os api, the operation has to record from here
965 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal);
966
967 return mapAddress;
968 }
969
970 // release a named shared memory region
971 //
972 static void unmap_shared(char* addr, size_t bytes) {
973 os::release_memory(addr, bytes);
974 }
975
976 // create the PerfData memory region in shared memory.
977 //
978 static char* create_shared_memory(size_t size) {
979
980 // create the shared memory region.
981 return mmap_create_shared(size);
982 }
983
984 // delete the shared PerfData memory region
985 //
986 static void delete_shared_memory(char* addr, size_t size) {
987
988 // cleanup the persistent shared memory resources. since DestroyJavaVM does
989 // not support unloading of the JVM, unmapping of the memory resource is
990 // not performed. The memory will be reclaimed by the OS upon termination of
991 // the process. The backing store file is deleted from the file system.
992
993 assert(!PerfDisableSharedMem, "shouldn't be here");
994
995 if (backing_store_file_name != NULL) {
996 remove_file(backing_store_file_name);
997 // Don't.. Free heap memory could deadlock os::abort() if it is called
998 // from signal handler. OS will reclaim the heap memory.
999 // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
1000 backing_store_file_name = NULL;
1001 }
1002 }
1003
1004 // return the size of the file for the given file descriptor
1005 // or 0 if it is not a valid size for a shared memory file
1006 //
1007 static size_t sharedmem_filesize(int fd, TRAPS) {
1008
1009 struct stat statbuf;
1010 int result;
1011
1012 RESTARTABLE(::fstat(fd, &statbuf), result);
1013 if (result == OS_ERR) {
1014 if (PrintMiscellaneous && Verbose) {
1015 warning("fstat failed: %s\n", strerror(errno));
1016 }
1017 THROW_MSG_0(vmSymbols::java_io_IOException(),
1018 "Could not determine PerfMemory size");
1019 }
1020
1021 if ((statbuf.st_size == 0) ||
1022 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
1023 THROW_MSG_0(vmSymbols::java_lang_Exception(),
1024 "Invalid PerfMemory size");
1025 }
1026
1027 return (size_t)statbuf.st_size;
1028 }
1029
1030 // attach to a named shared memory region.
1031 //
1032 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
1033
1034 char* mapAddress;
1035 int result;
1036 int fd;
1037 size_t size = 0;
1038 const char* luser = NULL;
1039
1040 int mmap_prot;
1041 int file_flags;
1042
1043 ResourceMark rm;
1044
1045 // map the high level access mode to the appropriate permission
1046 // constructs for the file and the shared memory mapping.
1047 if (mode == PerfMemory::PERF_MODE_RO) {
1048 mmap_prot = PROT_READ;
1049 file_flags = O_RDONLY | O_NOFOLLOW;
1050 }
1051 else if (mode == PerfMemory::PERF_MODE_RW) {
1052 #ifdef LATER
1053 mmap_prot = PROT_READ | PROT_WRITE;
1054 file_flags = O_RDWR | O_NOFOLLOW;
1055 #else
1056 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1057 "Unsupported access mode");
1058 #endif
1059 }
1060 else {
1061 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1062 "Illegal access mode");
1063 }
1064
1065 if (user == NULL || strlen(user) == 0) {
1066 luser = get_user_name(vmid, CHECK);
1067 }
1068 else {
1069 luser = user;
1070 }
1071
1072 if (luser == NULL) {
1073 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1074 "Could not map vmid to user Name");
1075 }
1076
1077 char* dirname = get_user_tmp_dir(luser);
1078
1079 // since we don't follow symbolic links when creating the backing
1080 // store file, we don't follow them when attaching either.
1081 //
1082 if (!is_directory_secure(dirname)) {
1083 FREE_C_HEAP_ARRAY(char, dirname);
1084 if (luser != user) {
1085 FREE_C_HEAP_ARRAY(char, luser);
1086 }
1087 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1088 "Process not found");
1089 }
1090
1091 char* filename = get_sharedmem_filename(dirname, vmid);
1092
1093 // copy heap memory to resource memory. the open_sharedmem_file
1094 // method below need to use the filename, but could throw an
1095 // exception. using a resource array prevents the leak that
1096 // would otherwise occur.
1097 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
1098 strcpy(rfilename, filename);
1099
1100 // free the c heap resources that are no longer needed
1101 if (luser != user) FREE_C_HEAP_ARRAY(char, luser);
1102 FREE_C_HEAP_ARRAY(char, dirname);
1103 FREE_C_HEAP_ARRAY(char, filename);
1104
1105 // open the shared memory file for the give vmid
1106 fd = open_sharedmem_file(rfilename, file_flags, CHECK);
1107 assert(fd != OS_ERR, "unexpected value");
1108
1109 if (*sizep == 0) {
1110 size = sharedmem_filesize(fd, CHECK);
1111 } else {
1112 size = *sizep;
1113 }
1114
1115 assert(size > 0, "unexpected size <= 0");
1116
1117 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
1118
1119 // attempt to close the file - restart if it gets interrupted,
1120 // but ignore other failures
1121 result = ::close(fd);
1122 assert(result != OS_ERR, "could not close file");
1123
1124 if (mapAddress == MAP_FAILED) {
1125 if (PrintMiscellaneous && Verbose) {
1126 warning("mmap failed: %s\n", strerror(errno));
1127 }
1128 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
1129 "Could not map PerfMemory");
1130 }
1131
1132 // it does not go through os api, the operation has to record from here
1133 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal);
1134
1135 *addr = mapAddress;
1136 *sizep = size;
1137
1138 if (PerfTraceMemOps) {
1139 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
1140 INTPTR_FORMAT "\n", size, vmid, p2i((void*)mapAddress));
1141 }
1142 }
1143
1144
1145
1146
1147 // create the PerfData memory region
1148 //
1149 // This method creates the memory region used to store performance
1150 // data for the JVM. The memory may be created in standard or
1151 // shared memory.
1152 //
1153 void PerfMemory::create_memory_region(size_t size) {
1154
1155 if (PerfDisableSharedMem) {
1156 // do not share the memory for the performance data.
1157 _start = create_standard_memory(size);
1158 }
1159 else {
1160 _start = create_shared_memory(size);
1161 if (_start == NULL) {
1162
1163 // creation of the shared memory region failed, attempt
1164 // to create a contiguous, non-shared memory region instead.
1165 //
1166 if (PrintMiscellaneous && Verbose) {
1167 warning("Reverting to non-shared PerfMemory region.\n");
1168 }
1169 PerfDisableSharedMem = true;
1170 _start = create_standard_memory(size);
1171 }
1172 }
1173
1174 if (_start != NULL) _capacity = size;
1175
1176 }
1177
1178 // delete the PerfData memory region
1179 //
1180 // This method deletes the memory region used to store performance
1181 // data for the JVM. The memory region indicated by the <address, size>
1182 // tuple will be inaccessible after a call to this method.
1183 //
1184 void PerfMemory::delete_memory_region() {
1185
1186 assert((start() != NULL && capacity() > 0), "verify proper state");
1187
1188 // If user specifies PerfDataSaveFile, it will save the performance data
1189 // to the specified file name no matter whether PerfDataSaveToFile is specified
1190 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
1191 // -XX:+PerfDataSaveToFile.
1192 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
1193 save_memory_to_file(start(), capacity());
1194 }
1195
1196 if (PerfDisableSharedMem) {
1197 delete_standard_memory(start(), capacity());
1198 }
1199 else {
1200 delete_shared_memory(start(), capacity());
1201 }
1202 }
1203
1204 // attach to the PerfData memory region for another JVM
1205 //
1206 // This method returns an <address, size> tuple that points to
1207 // a memory buffer that is kept reasonably synchronized with
1208 // the PerfData memory region for the indicated JVM. This
1209 // buffer may be kept in synchronization via shared memory
1210 // or some other mechanism that keeps the buffer updated.
1211 //
1212 // If the JVM chooses not to support the attachability feature,
1213 // this method should throw an UnsupportedOperation exception.
1214 //
1215 // This implementation utilizes named shared memory to map
1216 // the indicated process's PerfData memory region into this JVMs
1217 // address space.
1218 //
1219 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
1220
1221 if (vmid == 0 || vmid == os::current_process_id()) {
1222 *addrp = start();
1223 *sizep = capacity();
1224 return;
1225 }
1226
1227 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
1228 }
1229
1230 // detach from the PerfData memory region of another JVM
1231 //
1232 // This method detaches the PerfData memory region of another
1233 // JVM, specified as an <address, size> tuple of a buffer
1234 // in this process's address space. This method may perform
1235 // arbitrary actions to accomplish the detachment. The memory
1236 // region specified by <address, size> will be inaccessible after
1237 // a call to this method.
1238 //
1239 // If the JVM chooses not to support the attachability feature,
1240 // this method should throw an UnsupportedOperation exception.
1241 //
1242 // This implementation utilizes named shared memory to detach
1243 // the indicated process's PerfData memory region from this
1244 // process's address space.
1245 //
1246 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1247
1248 assert(addr != 0, "address sanity check");
1249 assert(bytes > 0, "capacity sanity check");
1250
1251 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1252 // prevent accidental detachment of this process's PerfMemory region
1253 return;
1254 }
1255
1256 unmap_shared(addr, bytes);
1257 }