1 /*
2 * Copyright (c) 2001, 2015, 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 and
379 // handle errors, otherwise shared memory files will be created in cwd.
380 result = fchdir(fd);
381 if (result == OS_ERR) {
382 if (PrintMiscellaneous && Verbose) {
383 warning("could not change to directory %s", dirname);
384 }
385 if (*saved_cwd_fd != -1) {
386 ::close(*saved_cwd_fd);
387 *saved_cwd_fd = -1;
388 }
389 // Close the directory.
390 os::closedir(dirp);
391 return NULL;
392 } else {
393 return dirp;
394 }
395 }
396
397 // Close the directory and restore the current working directory.
398 //
399 static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) {
400
401 int result;
402 // If we have a saved cwd change back to it and close the fd.
403 if (saved_cwd_fd != -1) {
404 result = fchdir(saved_cwd_fd);
405 ::close(saved_cwd_fd);
406 }
407
408 // Close the directory.
409 os::closedir(dirp);
410 }
411
412 // Check if the given file descriptor is considered a secure.
413 //
414 static bool is_file_secure(int fd, const char *filename) {
415
416 int result;
417 struct stat statbuf;
418
419 // Determine if the file is secure.
420 RESTARTABLE(::fstat(fd, &statbuf), result);
421 if (result == OS_ERR) {
422 if (PrintMiscellaneous && Verbose) {
423 warning("fstat failed on %s: %s\n", filename, strerror(errno));
424 }
425 return false;
426 }
427 if (statbuf.st_nlink > 1) {
428 // A file with multiple links is not expected.
429 if (PrintMiscellaneous && Verbose) {
430 warning("file %s has multiple links\n", filename);
431 }
432 return false;
433 }
434 return true;
435 }
436
437 // return the user name for the given user id
438 //
439 // the caller is expected to free the allocated memory.
440 //
441 static char* get_user_name(uid_t uid) {
442
443 struct passwd pwent;
444
445 // determine the max pwbuf size from sysconf, and hardcode
446 // a default if this not available through sysconf.
447 //
448 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
449 if (bufsize == -1)
450 bufsize = 1024;
451
452 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
453
454 // POSIX interface to getpwuid_r is used on LINUX
455 struct passwd* p;
456 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);
457
458 if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {
459 if (PrintMiscellaneous && Verbose) {
460 if (result != 0) {
461 warning("Could not retrieve passwd entry: %s\n",
462 strerror(result));
463 }
464 else if (p == NULL) {
465 // this check is added to protect against an observed problem
466 // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0,
467 // indicating success, but has p == NULL. This was observed when
468 // inserting a file descriptor exhaustion fault prior to the call
469 // getpwuid_r() call. In this case, error is set to the appropriate
470 // error condition, but this is undocumented behavior. This check
471 // is safe under any condition, but the use of errno in the output
472 // message may result in an erroneous message.
473 // Bug Id 89052 was opened with RedHat.
474 //
475 warning("Could not retrieve passwd entry: %s\n",
476 strerror(errno));
477 }
478 else {
479 warning("Could not determine user name: %s\n",
480 p->pw_name == NULL ? "pw_name = NULL" :
481 "pw_name zero length");
482 }
483 }
484 FREE_C_HEAP_ARRAY(char, pwbuf);
485 return NULL;
486 }
487
488 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal);
489 strcpy(user_name, p->pw_name);
490
491 FREE_C_HEAP_ARRAY(char, pwbuf);
492 return user_name;
493 }
494
495 // return the name of the user that owns the process identified by vmid.
496 //
497 // This method uses a slow directory search algorithm to find the backing
498 // store file for the specified vmid and returns the user name, as determined
499 // by the user name suffix of the hsperfdata_<username> directory name.
500 //
501 // the caller is expected to free the allocated memory.
502 //
503 static char* get_user_name_slow(int vmid, TRAPS) {
504
505 // short circuit the directory search if the process doesn't even exist.
506 if (kill(vmid, 0) == OS_ERR) {
507 if (errno == ESRCH) {
508 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
509 "Process not found");
510 }
511 else /* EPERM */ {
512 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));
513 }
514 }
515
516 // directory search
517 char* oldest_user = NULL;
518 time_t oldest_ctime = 0;
519
520 const char* tmpdirname = os::get_temp_directory();
521
522 // open the temp directory
523 DIR* tmpdirp = os::opendir(tmpdirname);
524
525 if (tmpdirp == NULL) {
526 // Cannot open the directory to get the user name, return.
527 return NULL;
528 }
529
530 // for each entry in the directory that matches the pattern hsperfdata_*,
531 // open the directory and check if the file for the given vmid exists.
532 // The file with the expected name and the latest creation date is used
533 // to determine the user name for the process id.
534 //
535 struct dirent* dentry;
536 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
537 errno = 0;
538 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
539
540 // check if the directory entry is a hsperfdata file
541 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
542 continue;
543 }
544
545 char* usrdir_name = NEW_C_HEAP_ARRAY(char,
546 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
547 strcpy(usrdir_name, tmpdirname);
548 strcat(usrdir_name, "/");
549 strcat(usrdir_name, dentry->d_name);
550
551 // open the user directory
552 DIR* subdirp = open_directory_secure(usrdir_name);
553
554 if (subdirp == NULL) {
555 FREE_C_HEAP_ARRAY(char, usrdir_name);
556 continue;
557 }
558
559 struct dirent* udentry;
560 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
561 errno = 0;
562 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
563
564 if (filename_to_pid(udentry->d_name) == vmid) {
565 struct stat statbuf;
566 int result;
567
568 char* filename = NEW_C_HEAP_ARRAY(char,
569 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
570
571 strcpy(filename, usrdir_name);
572 strcat(filename, "/");
573 strcat(filename, udentry->d_name);
574
575 // don't follow symbolic links for the file
576 RESTARTABLE(::lstat(filename, &statbuf), result);
577 if (result == OS_ERR) {
578 FREE_C_HEAP_ARRAY(char, filename);
579 continue;
580 }
581
582 // skip over files that are not regular files.
583 if (!S_ISREG(statbuf.st_mode)) {
584 FREE_C_HEAP_ARRAY(char, filename);
585 continue;
586 }
587
588 // compare and save filename with latest creation time
589 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
590
591 if (statbuf.st_ctime > oldest_ctime) {
592 char* user = strchr(dentry->d_name, '_') + 1;
593
594 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user);
595 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal);
596
597 strcpy(oldest_user, user);
598 oldest_ctime = statbuf.st_ctime;
599 }
600 }
601
602 FREE_C_HEAP_ARRAY(char, filename);
603 }
604 }
605 os::closedir(subdirp);
606 FREE_C_HEAP_ARRAY(char, udbuf);
607 FREE_C_HEAP_ARRAY(char, usrdir_name);
608 }
609 os::closedir(tmpdirp);
610 FREE_C_HEAP_ARRAY(char, tdbuf);
611
612 return(oldest_user);
613 }
614
615 // return the name of the user that owns the JVM indicated by the given vmid.
616 //
617 static char* get_user_name(int vmid, TRAPS) {
618 return get_user_name_slow(vmid, THREAD);
619 }
620
621 // return the file name of the backing store file for the named
622 // shared memory region for the given user name and vmid.
623 //
624 // the caller is expected to free the allocated memory.
625 //
626 static char* get_sharedmem_filename(const char* dirname, int vmid) {
627
628 // add 2 for the file separator and a null terminator.
629 size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
630
631 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
632 snprintf(name, nbytes, "%s/%d", dirname, vmid);
633
634 return name;
635 }
636
637
638 // remove file
639 //
640 // this method removes the file specified by the given path
641 //
642 static void remove_file(const char* path) {
643
644 int result;
645
646 // if the file is a directory, the following unlink will fail. since
647 // we don't expect to find directories in the user temp directory, we
648 // won't try to handle this situation. even if accidentially or
649 // maliciously planted, the directory's presence won't hurt anything.
650 //
651 RESTARTABLE(::unlink(path), result);
652 if (PrintMiscellaneous && Verbose && result == OS_ERR) {
653 if (errno != ENOENT) {
654 warning("Could not unlink shared memory backing"
655 " store file %s : %s\n", path, strerror(errno));
656 }
657 }
658 }
659
660
661 // cleanup stale shared memory resources
662 //
663 // This method attempts to remove all stale shared memory files in
664 // the named user temporary directory. It scans the named directory
665 // for files matching the pattern ^$[0-9]*$. For each file found, the
666 // process id is extracted from the file name and a test is run to
667 // determine if the process is alive. If the process is not alive,
668 // any stale file resources are removed.
669 //
670 static void cleanup_sharedmem_resources(const char* dirname) {
671
672 int saved_cwd_fd;
673 // open the directory and set the current working directory to it
674 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
675 if (dirp == NULL) {
676 // directory doesn't exist or is insecure, so there is nothing to cleanup
677 return;
678 }
679
680 // for each entry in the directory that matches the expected file
681 // name pattern, determine if the file resources are stale and if
682 // so, remove the file resources. Note, instrumented HotSpot processes
683 // for this user may start and/or terminate during this search and
684 // remove or create new files in this directory. The behavior of this
685 // loop under these conditions is dependent upon the implementation of
686 // opendir/readdir.
687 //
688 struct dirent* entry;
689 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
690
691 errno = 0;
692 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
693
694 pid_t pid = filename_to_pid(entry->d_name);
695
696 if (pid == 0) {
697
698 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
699
700 // attempt to remove all unexpected files, except "." and ".."
701 unlink(entry->d_name);
702 }
703
704 errno = 0;
705 continue;
706 }
707
708 // we now have a file name that converts to a valid integer
709 // that could represent a process id . if this process id
710 // matches the current process id or the process is not running,
711 // then remove the stale file resources.
712 //
713 // process liveness is detected by sending signal number 0 to
714 // the process id (see kill(2)). if kill determines that the
715 // process does not exist, then the file resources are removed.
716 // if kill determines that that we don't have permission to
717 // signal the process, then the file resources are assumed to
718 // be stale and are removed because the resources for such a
719 // process should be in a different user specific directory.
720 //
721 if ((pid == os::current_process_id()) ||
722 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
723
724 unlink(entry->d_name);
725 }
726 errno = 0;
727 }
728
729 // close the directory and reset the current working directory
730 close_directory_secure_cwd(dirp, saved_cwd_fd);
731
732 FREE_C_HEAP_ARRAY(char, dbuf);
733 }
734
735 // make the user specific temporary directory. Returns true if
736 // the directory exists and is secure upon return. Returns false
737 // if the directory exists but is either a symlink, is otherwise
738 // insecure, or if an error occurred.
739 //
740 static bool make_user_tmp_dir(const char* dirname) {
741
742 // create the directory with 0755 permissions. note that the directory
743 // will be owned by euid::egid, which may not be the same as uid::gid.
744 //
745 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
746 if (errno == EEXIST) {
747 // The directory already exists and was probably created by another
748 // JVM instance. However, this could also be the result of a
749 // deliberate symlink. Verify that the existing directory is safe.
750 //
751 if (!is_directory_secure(dirname)) {
752 // directory is not secure
753 if (PrintMiscellaneous && Verbose) {
754 warning("%s directory is insecure\n", dirname);
755 }
756 return false;
757 }
758 }
759 else {
760 // we encountered some other failure while attempting
761 // to create the directory
762 //
763 if (PrintMiscellaneous && Verbose) {
764 warning("could not create directory %s: %s\n",
765 dirname, strerror(errno));
766 }
767 return false;
768 }
769 }
770 return true;
771 }
772
773 // create the shared memory file resources
774 //
775 // This method creates the shared memory file with the given size
776 // This method also creates the user specific temporary directory, if
777 // it does not yet exist.
778 //
779 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
780
781 // make the user temporary directory
782 if (!make_user_tmp_dir(dirname)) {
783 // could not make/find the directory or the found directory
784 // was not secure
785 return -1;
786 }
787
788 int saved_cwd_fd;
789 // open the directory and set the current working directory to it
790 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
791 if (dirp == NULL) {
792 // Directory doesn't exist or is insecure, so cannot create shared
793 // memory file.
794 return -1;
795 }
796
797 // Open the filename in the current directory.
798 // Cannot use O_TRUNC here; truncation of an existing file has to happen
799 // after the is_file_secure() check below.
800 int result;
801 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result);
802 if (result == OS_ERR) {
803 if (PrintMiscellaneous && Verbose) {
804 if (errno == ELOOP) {
805 warning("file %s is a symlink and is not secure\n", filename);
806 } else {
807 warning("could not create file %s: %s\n", filename, strerror(errno));
808 }
809 }
810 // close the directory and reset the current working directory
811 close_directory_secure_cwd(dirp, saved_cwd_fd);
812
813 return -1;
814 }
815 // close the directory and reset the current working directory
816 close_directory_secure_cwd(dirp, saved_cwd_fd);
817
818 // save the file descriptor
819 int fd = result;
820
821 // check to see if the file is secure
822 if (!is_file_secure(fd, filename)) {
823 ::close(fd);
824 return -1;
825 }
826
827 // truncate the file to get rid of any existing data
828 RESTARTABLE(::ftruncate(fd, (off_t)0), result);
829 if (result == OS_ERR) {
830 if (PrintMiscellaneous && Verbose) {
831 warning("could not truncate shared memory file: %s\n", strerror(errno));
832 }
833 ::close(fd);
834 return -1;
835 }
836 // set the file size
837 RESTARTABLE(::ftruncate(fd, (off_t)size), result);
838 if (result == OS_ERR) {
839 if (PrintMiscellaneous && Verbose) {
840 warning("could not set shared memory file size: %s\n", strerror(errno));
841 }
842 ::close(fd);
843 return -1;
844 }
845
846 // Verify that we have enough disk space for this file.
847 // We'll get random SIGBUS crashes on memory accesses if
848 // we don't.
849
850 for (size_t seekpos = 0; seekpos < size; seekpos += os::vm_page_size()) {
851 int zero_int = 0;
852 result = (int)os::seek_to_file_offset(fd, (jlong)(seekpos));
853 if (result == -1 ) break;
854 RESTARTABLE(::write(fd, &zero_int, 1), result);
855 if (result != 1) {
856 if (errno == ENOSPC) {
857 warning("Insufficient space for shared memory file:\n %s\nTry using the -Djava.io.tmpdir= option to select an alternate temp location.\n", filename);
858 }
859 break;
860 }
861 }
862
863 if (result != -1) {
864 return fd;
865 } else {
866 ::close(fd);
867 return -1;
868 }
869 }
870
871 // open the shared memory file for the given user and vmid. returns
872 // the file descriptor for the open file or -1 if the file could not
873 // be opened.
874 //
875 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
876
877 // open the file
878 int result;
879 RESTARTABLE(::open(filename, oflags), result);
880 if (result == OS_ERR) {
881 if (errno == ENOENT) {
882 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
883 "Process not found", OS_ERR);
884 }
885 else if (errno == EACCES) {
886 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
887 "Permission denied", OS_ERR);
888 }
889 else {
890 THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR);
891 }
892 }
893 int fd = result;
894
895 // check to see if the file is secure
896 if (!is_file_secure(fd, filename)) {
897 ::close(fd);
898 return -1;
899 }
900
901 return fd;
902 }
903
904 // create a named shared memory region. returns the address of the
905 // memory region on success or NULL on failure. A return value of
906 // NULL will ultimately disable the shared memory feature.
907 //
908 // On Solaris and Bsd, the name space for shared memory objects
909 // is the file system name space.
910 //
911 // A monitoring application attaching to a JVM does not need to know
912 // the file system name of the shared memory object. However, it may
913 // be convenient for applications to discover the existence of newly
914 // created and terminating JVMs by watching the file system name space
915 // for files being created or removed.
916 //
917 static char* mmap_create_shared(size_t size) {
918
919 int result;
920 int fd;
921 char* mapAddress;
922
923 int vmid = os::current_process_id();
924
925 char* user_name = get_user_name(geteuid());
926
927 if (user_name == NULL)
928 return NULL;
929
930 char* dirname = get_user_tmp_dir(user_name);
931 char* filename = get_sharedmem_filename(dirname, vmid);
932
933 // get the short filename
934 char* short_filename = strrchr(filename, '/');
935 if (short_filename == NULL) {
936 short_filename = filename;
937 } else {
938 short_filename++;
939 }
940
941 // cleanup any stale shared memory files
942 cleanup_sharedmem_resources(dirname);
943
944 assert(((size > 0) && (size % os::vm_page_size() == 0)),
945 "unexpected PerfMemory region size");
946
947 fd = create_sharedmem_resources(dirname, short_filename, size);
948
949 FREE_C_HEAP_ARRAY(char, user_name);
950 FREE_C_HEAP_ARRAY(char, dirname);
951
952 if (fd == -1) {
953 FREE_C_HEAP_ARRAY(char, filename);
954 return NULL;
955 }
956
957 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
958
959 result = ::close(fd);
960 assert(result != OS_ERR, "could not close file");
961
962 if (mapAddress == MAP_FAILED) {
963 if (PrintMiscellaneous && Verbose) {
964 warning("mmap failed - %s\n", strerror(errno));
965 }
966 remove_file(filename);
967 FREE_C_HEAP_ARRAY(char, filename);
968 return NULL;
969 }
970
971 // save the file name for use in delete_shared_memory()
972 backing_store_file_name = filename;
973
974 // clear the shared memory region
975 (void)::memset((void*) mapAddress, 0, size);
976
977 // it does not go through os api, the operation has to record from here
978 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal);
979
980 return mapAddress;
981 }
982
983 // release a named shared memory region
984 //
985 static void unmap_shared(char* addr, size_t bytes) {
986 os::release_memory(addr, bytes);
987 }
988
989 // create the PerfData memory region in shared memory.
990 //
991 static char* create_shared_memory(size_t size) {
992
993 // create the shared memory region.
994 return mmap_create_shared(size);
995 }
996
997 // delete the shared PerfData memory region
998 //
999 static void delete_shared_memory(char* addr, size_t size) {
1000
1001 // cleanup the persistent shared memory resources. since DestroyJavaVM does
1002 // not support unloading of the JVM, unmapping of the memory resource is
1003 // not performed. The memory will be reclaimed by the OS upon termination of
1004 // the process. The backing store file is deleted from the file system.
1005
1006 assert(!PerfDisableSharedMem, "shouldn't be here");
1007
1008 if (backing_store_file_name != NULL) {
1009 remove_file(backing_store_file_name);
1010 // Don't.. Free heap memory could deadlock os::abort() if it is called
1011 // from signal handler. OS will reclaim the heap memory.
1012 // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
1013 backing_store_file_name = NULL;
1014 }
1015 }
1016
1017 // return the size of the file for the given file descriptor
1018 // or 0 if it is not a valid size for a shared memory file
1019 //
1020 static size_t sharedmem_filesize(int fd, TRAPS) {
1021
1022 struct stat statbuf;
1023 int result;
1024
1025 RESTARTABLE(::fstat(fd, &statbuf), result);
1026 if (result == OS_ERR) {
1027 if (PrintMiscellaneous && Verbose) {
1028 warning("fstat failed: %s\n", strerror(errno));
1029 }
1030 THROW_MSG_0(vmSymbols::java_io_IOException(),
1031 "Could not determine PerfMemory size");
1032 }
1033
1034 if ((statbuf.st_size == 0) ||
1035 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
1036 THROW_MSG_0(vmSymbols::java_lang_Exception(),
1037 "Invalid PerfMemory size");
1038 }
1039
1040 return (size_t)statbuf.st_size;
1041 }
1042
1043 // attach to a named shared memory region.
1044 //
1045 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
1046
1047 char* mapAddress;
1048 int result;
1049 int fd;
1050 size_t size = 0;
1051 const char* luser = NULL;
1052
1053 int mmap_prot;
1054 int file_flags;
1055
1056 ResourceMark rm;
1057
1058 // map the high level access mode to the appropriate permission
1059 // constructs for the file and the shared memory mapping.
1060 if (mode == PerfMemory::PERF_MODE_RO) {
1061 mmap_prot = PROT_READ;
1062 file_flags = O_RDONLY | O_NOFOLLOW;
1063 }
1064 else if (mode == PerfMemory::PERF_MODE_RW) {
1065 #ifdef LATER
1066 mmap_prot = PROT_READ | PROT_WRITE;
1067 file_flags = O_RDWR | O_NOFOLLOW;
1068 #else
1069 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1070 "Unsupported access mode");
1071 #endif
1072 }
1073 else {
1074 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1075 "Illegal access mode");
1076 }
1077
1078 if (user == NULL || strlen(user) == 0) {
1079 luser = get_user_name(vmid, CHECK);
1080 }
1081 else {
1082 luser = user;
1083 }
1084
1085 if (luser == NULL) {
1086 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1087 "Could not map vmid to user Name");
1088 }
1089
1090 char* dirname = get_user_tmp_dir(luser);
1091
1092 // since we don't follow symbolic links when creating the backing
1093 // store file, we don't follow them when attaching either.
1094 //
1095 if (!is_directory_secure(dirname)) {
1096 FREE_C_HEAP_ARRAY(char, dirname);
1097 if (luser != user) {
1098 FREE_C_HEAP_ARRAY(char, luser);
1099 }
1100 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1101 "Process not found");
1102 }
1103
1104 char* filename = get_sharedmem_filename(dirname, vmid);
1105
1106 // copy heap memory to resource memory. the open_sharedmem_file
1107 // method below need to use the filename, but could throw an
1108 // exception. using a resource array prevents the leak that
1109 // would otherwise occur.
1110 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
1111 strcpy(rfilename, filename);
1112
1113 // free the c heap resources that are no longer needed
1114 if (luser != user) FREE_C_HEAP_ARRAY(char, luser);
1115 FREE_C_HEAP_ARRAY(char, dirname);
1116 FREE_C_HEAP_ARRAY(char, filename);
1117
1118 // open the shared memory file for the give vmid
1119 fd = open_sharedmem_file(rfilename, file_flags, CHECK);
1120 assert(fd != OS_ERR, "unexpected value");
1121
1122 if (*sizep == 0) {
1123 size = sharedmem_filesize(fd, CHECK);
1124 } else {
1125 size = *sizep;
1126 }
1127
1128 assert(size > 0, "unexpected size <= 0");
1129
1130 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
1131
1132 // attempt to close the file - restart if it gets interrupted,
1133 // but ignore other failures
1134 result = ::close(fd);
1135 assert(result != OS_ERR, "could not close file");
1136
1137 if (mapAddress == MAP_FAILED) {
1138 if (PrintMiscellaneous && Verbose) {
1139 warning("mmap failed: %s\n", strerror(errno));
1140 }
1141 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
1142 "Could not map PerfMemory");
1143 }
1144
1145 // it does not go through os api, the operation has to record from here
1146 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal);
1147
1148 *addr = mapAddress;
1149 *sizep = size;
1150
1151 if (PerfTraceMemOps) {
1152 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
1153 INTPTR_FORMAT "\n", size, vmid, p2i((void*)mapAddress));
1154 }
1155 }
1156
1157
1158
1159
1160 // create the PerfData memory region
1161 //
1162 // This method creates the memory region used to store performance
1163 // data for the JVM. The memory may be created in standard or
1164 // shared memory.
1165 //
1166 void PerfMemory::create_memory_region(size_t size) {
1167
1168 if (PerfDisableSharedMem) {
1169 // do not share the memory for the performance data.
1170 _start = create_standard_memory(size);
1171 }
1172 else {
1173 _start = create_shared_memory(size);
1174 if (_start == NULL) {
1175
1176 // creation of the shared memory region failed, attempt
1177 // to create a contiguous, non-shared memory region instead.
1178 //
1179 if (PrintMiscellaneous && Verbose) {
1180 warning("Reverting to non-shared PerfMemory region.\n");
1181 }
1182 PerfDisableSharedMem = true;
1183 _start = create_standard_memory(size);
1184 }
1185 }
1186
1187 if (_start != NULL) _capacity = size;
1188
1189 }
1190
1191 // delete the PerfData memory region
1192 //
1193 // This method deletes the memory region used to store performance
1194 // data for the JVM. The memory region indicated by the <address, size>
1195 // tuple will be inaccessible after a call to this method.
1196 //
1197 void PerfMemory::delete_memory_region() {
1198
1199 assert((start() != NULL && capacity() > 0), "verify proper state");
1200
1201 // If user specifies PerfDataSaveFile, it will save the performance data
1202 // to the specified file name no matter whether PerfDataSaveToFile is specified
1203 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
1204 // -XX:+PerfDataSaveToFile.
1205 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
1206 save_memory_to_file(start(), capacity());
1207 }
1208
1209 if (PerfDisableSharedMem) {
1210 delete_standard_memory(start(), capacity());
1211 }
1212 else {
1213 delete_shared_memory(start(), capacity());
1214 }
1215 }
1216
1217 // attach to the PerfData memory region for another JVM
1218 //
1219 // This method returns an <address, size> tuple that points to
1220 // a memory buffer that is kept reasonably synchronized with
1221 // the PerfData memory region for the indicated JVM. This
1222 // buffer may be kept in synchronization via shared memory
1223 // or some other mechanism that keeps the buffer updated.
1224 //
1225 // If the JVM chooses not to support the attachability feature,
1226 // this method should throw an UnsupportedOperation exception.
1227 //
1228 // This implementation utilizes named shared memory to map
1229 // the indicated process's PerfData memory region into this JVMs
1230 // address space.
1231 //
1232 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
1233
1234 if (vmid == 0 || vmid == os::current_process_id()) {
1235 *addrp = start();
1236 *sizep = capacity();
1237 return;
1238 }
1239
1240 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
1241 }
1242
1243 // detach from the PerfData memory region of another JVM
1244 //
1245 // This method detaches the PerfData memory region of another
1246 // JVM, specified as an <address, size> tuple of a buffer
1247 // in this process's address space. This method may perform
1248 // arbitrary actions to accomplish the detachment. The memory
1249 // region specified by <address, size> will be inaccessible after
1250 // a call to this method.
1251 //
1252 // If the JVM chooses not to support the attachability feature,
1253 // this method should throw an UnsupportedOperation exception.
1254 //
1255 // This implementation utilizes named shared memory to detach
1256 // the indicated process's PerfData memory region from this
1257 // process's address space.
1258 //
1259 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1260
1261 assert(addr != 0, "address sanity check");
1262 assert(bytes > 0, "capacity sanity check");
1263
1264 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1265 // prevent accidental detachment of this process's PerfMemory region
1266 return;
1267 }
1268
1269 unmap_shared(addr, bytes);
1270 }