1 /*
2 * Copyright (c) 2001, 2016, 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/os.hpp"
33 #include "runtime/perfMemory.hpp"
34 #include "services/memTracker.hpp"
35 #include "utilities/exceptions.hpp"
36
37 // put OS-includes here
38 # include <sys/types.h>
39 # include <sys/mman.h>
40 # include <errno.h>
41 # include <stdio.h>
42 # include <unistd.h>
43 # include <sys/stat.h>
44 # include <signal.h>
45 # include <pwd.h>
46
47 static char* backing_store_file_name = NULL; // name of the backing store
48 // file, if successfully created.
49
50 // Standard Memory Implementation Details
51
52 // create the PerfData memory region in standard memory.
53 //
54 static char* create_standard_memory(size_t size) {
55
56 // allocate an aligned chuck of memory
57 char* mapAddress = os::reserve_memory(size);
58
59 if (mapAddress == NULL) {
60 return NULL;
61 }
62
63 // commit memory
64 if (!os::commit_memory(mapAddress, size, !ExecMem)) {
65 if (PrintMiscellaneous && Verbose) {
66 warning("Could not commit PerfData memory\n");
67 }
68 os::release_memory(mapAddress, size);
69 return NULL;
70 }
71
72 return mapAddress;
73 }
74
75 // delete the PerfData memory region
76 //
77 static void delete_standard_memory(char* addr, size_t size) {
78
79 // there are no persistent external resources to cleanup for standard
80 // memory. since DestroyJavaVM does not support unloading of the JVM,
81 // cleanup of the memory resource is not performed. The memory will be
82 // reclaimed by the OS upon termination of the process.
83 //
84 return;
85 }
86
87 // save the specified memory region to the given file
88 //
89 // Note: this function might be called from signal handler (by os::abort()),
90 // don't allocate heap memory.
91 //
92 static void save_memory_to_file(char* addr, size_t size) {
93
94 const char* destfile = PerfMemory::get_perfdata_file_path();
95 assert(destfile[0] != '\0', "invalid PerfData file path");
96
97 int result;
98
99 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE),
100 result);;
101 if (result == OS_ERR) {
102 if (PrintMiscellaneous && Verbose) {
103 warning("Could not create Perfdata save file: %s: %s\n",
104 destfile, os::strerror(errno));
105 }
106 } else {
107 int fd = result;
108
109 for (size_t remaining = size; remaining > 0;) {
110
111 RESTARTABLE(::write(fd, addr, remaining), result);
112 if (result == OS_ERR) {
113 if (PrintMiscellaneous && Verbose) {
114 warning("Could not write Perfdata save file: %s: %s\n",
115 destfile, os::strerror(errno));
116 }
117 break;
118 }
119
120 remaining -= (size_t)result;
121 addr += result;
122 }
123
124 result = ::close(fd);
125 if (PrintMiscellaneous && Verbose) {
126 if (result == OS_ERR) {
127 warning("Could not close %s: %s\n", destfile, os::strerror(errno));
128 }
129 }
130 }
131 FREE_C_HEAP_ARRAY(char, destfile);
132 }
133
134
135 // Shared Memory Implementation Details
136
137 // Note: the solaris and bsd shared memory implementation uses the mmap
138 // interface with a backing store file to implement named shared memory.
139 // Using the file system as the name space for shared memory allows a
140 // common name space to be supported across a variety of platforms. It
141 // also provides a name space that Java applications can deal with through
142 // simple file apis.
143 //
144 // The solaris and bsd implementations store the backing store file in
145 // a user specific temporary directory located in the /tmp file system,
146 // which is always a local file system and is sometimes a RAM based file
147 // system.
148
149 // return the user specific temporary directory name.
150 //
151 // the caller is expected to free the allocated memory.
152 //
153 static char* get_user_tmp_dir(const char* user) {
154
155 const char* tmpdir = os::get_temp_directory();
156 const char* perfdir = PERFDATA_NAME;
157 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3;
158 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
159
160 // construct the path name to user specific tmp directory
161 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user);
162
163 return dirname;
164 }
165
166 // convert the given file name into a process id. if the file
167 // does not meet the file naming constraints, return 0.
168 //
169 static pid_t filename_to_pid(const char* filename) {
170
171 // a filename that doesn't begin with a digit is not a
172 // candidate for conversion.
173 //
174 if (!isdigit(*filename)) {
175 return 0;
176 }
177
178 // check if file name can be converted to an integer without
179 // any leftover characters.
180 //
181 char* remainder = NULL;
182 errno = 0;
183 pid_t pid = (pid_t)strtol(filename, &remainder, 10);
184
185 if (errno != 0) {
186 return 0;
187 }
188
189 // check for left over characters. If any, then the filename is
190 // not a candidate for conversion.
191 //
192 if (remainder != NULL && *remainder != '\0') {
193 return 0;
194 }
195
196 // successful conversion, return the pid
197 return pid;
198 }
199
200
201 // Check if the given statbuf is considered a secure directory for
202 // the backing store files. Returns true if the directory is considered
203 // a secure location. Returns false if the statbuf is a symbolic link or
204 // if an error occurred.
205 //
206 static bool is_statbuf_secure(struct stat *statp) {
207 if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) {
208 // The path represents a link or some non-directory file type,
209 // which is not what we expected. Declare it insecure.
210 //
211 return false;
212 }
213 // We have an existing directory, check if the permissions are safe.
214 //
215 if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) {
216 // The directory is open for writing and could be subjected
217 // to a symlink or a hard link attack. Declare it insecure.
218 //
219 return false;
220 }
221 // If user is not root then see if the uid of the directory matches the effective uid of the process.
222 uid_t euid = geteuid();
223 if ((euid != 0) && (statp->st_uid != euid)) {
224 // The directory was not created by this user, declare it insecure.
225 //
226 return false;
227 }
228 return true;
229 }
230
231
232 // Check if the given path is considered a secure directory for
233 // the backing store files. Returns true if the directory exists
234 // and is considered a secure location. Returns false if the path
235 // is a symbolic link or if an error occurred.
236 //
237 static bool is_directory_secure(const char* path) {
238 struct stat statbuf;
239 int result = 0;
240
241 RESTARTABLE(::lstat(path, &statbuf), result);
242 if (result == OS_ERR) {
243 return false;
244 }
245
246 // The path exists, see if it is secure.
247 return is_statbuf_secure(&statbuf);
248 }
249
250
251 // Check if the given directory file descriptor is considered a secure
252 // directory for the backing store files. Returns true if the directory
253 // exists and is considered a secure location. Returns false if the path
254 // is a symbolic link or if an error occurred.
255 //
256 static bool is_dirfd_secure(int dir_fd) {
257 struct stat statbuf;
258 int result = 0;
259
260 RESTARTABLE(::fstat(dir_fd, &statbuf), result);
261 if (result == OS_ERR) {
262 return false;
263 }
264
265 // The path exists, now check its mode.
266 return is_statbuf_secure(&statbuf);
267 }
268
269
270 // Check to make sure fd1 and fd2 are referencing the same file system object.
271 //
272 static bool is_same_fsobject(int fd1, int fd2) {
273 struct stat statbuf1;
274 struct stat statbuf2;
275 int result = 0;
276
277 RESTARTABLE(::fstat(fd1, &statbuf1), result);
278 if (result == OS_ERR) {
279 return false;
280 }
281 RESTARTABLE(::fstat(fd2, &statbuf2), result);
282 if (result == OS_ERR) {
283 return false;
284 }
285
286 if ((statbuf1.st_ino == statbuf2.st_ino) &&
287 (statbuf1.st_dev == statbuf2.st_dev)) {
288 return true;
289 } else {
290 return false;
291 }
292 }
293
294
295 // Open the directory of the given path and validate it.
296 // Return a DIR * of the open directory.
297 //
298 static DIR *open_directory_secure(const char* dirname) {
299 // Open the directory using open() so that it can be verified
300 // to be secure by calling is_dirfd_secure(), opendir() and then check
301 // to see if they are the same file system object. This method does not
302 // introduce a window of opportunity for the directory to be attacked that
303 // calling opendir() and is_directory_secure() does.
304 int result;
305 DIR *dirp = NULL;
306 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result);
307 if (result == OS_ERR) {
308 // Directory doesn't exist or is a symlink, so there is nothing to cleanup.
309 if (PrintMiscellaneous && Verbose) {
310 if (errno == ELOOP) {
311 warning("directory %s is a symlink and is not secure\n", dirname);
312 } else {
313 warning("could not open directory %s: %s\n", dirname, os::strerror(errno));
314 }
315 }
316 return dirp;
317 }
318 int fd = result;
319
320 // Determine if the open directory is secure.
321 if (!is_dirfd_secure(fd)) {
322 // The directory is not a secure directory.
323 os::close(fd);
324 return dirp;
325 }
326
327 // Open the directory.
328 dirp = ::opendir(dirname);
329 if (dirp == NULL) {
330 // The directory doesn't exist, close fd and return.
331 os::close(fd);
332 return dirp;
333 }
334
335 // Check to make sure fd and dirp are referencing the same file system object.
336 if (!is_same_fsobject(fd, dirfd(dirp))) {
337 // The directory is not secure.
338 os::close(fd);
339 os::closedir(dirp);
340 dirp = NULL;
341 return dirp;
342 }
343
344 // Close initial open now that we know directory is secure
345 os::close(fd);
346
347 return dirp;
348 }
349
350 // NOTE: The code below uses fchdir(), open() and unlink() because
351 // fdopendir(), openat() and unlinkat() are not supported on all
352 // versions. Once the support for fdopendir(), openat() and unlinkat()
353 // is available on all supported versions the code can be changed
354 // to use these functions.
355
356 // Open the directory of the given path, validate it and set the
357 // current working directory to it.
358 // Return a DIR * of the open directory and the saved cwd fd.
359 //
360 static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) {
361
362 // Open the directory.
363 DIR* dirp = open_directory_secure(dirname);
364 if (dirp == NULL) {
365 // Directory doesn't exist or is insecure, so there is nothing to cleanup.
366 return dirp;
367 }
368 int fd = dirfd(dirp);
369
370 // Open a fd to the cwd and save it off.
371 int result;
372 RESTARTABLE(::open(".", O_RDONLY), result);
373 if (result == OS_ERR) {
374 *saved_cwd_fd = -1;
375 } else {
376 *saved_cwd_fd = result;
377 }
378
379 // Set the current directory to dirname by using the fd of the directory and
380 // handle errors, otherwise shared memory files will be created in cwd.
381 result = fchdir(fd);
382 if (result == OS_ERR) {
383 if (PrintMiscellaneous && Verbose) {
384 warning("could not change to directory %s", dirname);
385 }
386 if (*saved_cwd_fd != -1) {
387 ::close(*saved_cwd_fd);
388 *saved_cwd_fd = -1;
389 }
390 // Close the directory.
391 os::closedir(dirp);
392 return NULL;
393 } else {
394 return dirp;
395 }
396 }
397
398 // Close the directory and restore the current working directory.
399 //
400 static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) {
401
402 int result;
403 // If we have a saved cwd change back to it and close the fd.
404 if (saved_cwd_fd != -1) {
405 result = fchdir(saved_cwd_fd);
406 ::close(saved_cwd_fd);
407 }
408
409 // Close the directory.
410 os::closedir(dirp);
411 }
412
413 // Check if the given file descriptor is considered a secure.
414 //
415 static bool is_file_secure(int fd, const char *filename) {
416
417 int result;
418 struct stat statbuf;
419
420 // Determine if the file is secure.
421 RESTARTABLE(::fstat(fd, &statbuf), result);
422 if (result == OS_ERR) {
423 if (PrintMiscellaneous && Verbose) {
424 warning("fstat failed on %s: %s\n", filename, os::strerror(errno));
425 }
426 return false;
427 }
428 if (statbuf.st_nlink > 1) {
429 // A file with multiple links is not expected.
430 if (PrintMiscellaneous && Verbose) {
431 warning("file %s has multiple links\n", filename);
432 }
433 return false;
434 }
435 return true;
436 }
437
438 // return the user name for the given user id
439 //
440 // the caller is expected to free the allocated memory.
441 //
442 static char* get_user_name(uid_t uid) {
443
444 struct passwd pwent;
445
446 // determine the max pwbuf size from sysconf, and hardcode
447 // a default if this not available through sysconf.
448 //
449 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
450 if (bufsize == -1)
451 bufsize = 1024;
452
453 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
454
455 // POSIX interface to getpwuid_r is used on LINUX
456 struct passwd* p;
457 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);
458
459 if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {
460 if (PrintMiscellaneous && Verbose) {
461 if (result != 0) {
462 warning("Could not retrieve passwd entry: %s\n",
463 os::strerror(result));
464 }
465 else if (p == NULL) {
466 // this check is added to protect against an observed problem
467 // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0,
468 // indicating success, but has p == NULL. This was observed when
469 // inserting a file descriptor exhaustion fault prior to the call
470 // getpwuid_r() call. In this case, error is set to the appropriate
471 // error condition, but this is undocumented behavior. This check
472 // is safe under any condition, but the use of errno in the output
473 // message may result in an erroneous message.
474 // Bug Id 89052 was opened with RedHat.
475 //
476 warning("Could not retrieve passwd entry: %s\n",
477 os::strerror(errno));
478 }
479 else {
480 warning("Could not determine user name: %s\n",
481 p->pw_name == NULL ? "pw_name = NULL" :
482 "pw_name zero length");
483 }
484 }
485 FREE_C_HEAP_ARRAY(char, pwbuf);
486 return NULL;
487 }
488
489 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal);
490 strcpy(user_name, p->pw_name);
491
492 FREE_C_HEAP_ARRAY(char, pwbuf);
493 return user_name;
494 }
495
496 // return the name of the user that owns the process identified by vmid.
497 //
498 // This method uses a slow directory search algorithm to find the backing
499 // store file for the specified vmid and returns the user name, as determined
500 // by the user name suffix of the hsperfdata_<username> directory name.
501 //
502 // the caller is expected to free the allocated memory.
503 //
504 static char* get_user_name_slow(int vmid, TRAPS) {
505
506 // short circuit the directory search if the process doesn't even exist.
507 if (kill(vmid, 0) == OS_ERR) {
508 if (errno == ESRCH) {
509 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
510 "Process not found");
511 }
512 else /* EPERM */ {
513 THROW_MSG_0(vmSymbols::java_io_IOException(), os::strerror(errno));
514 }
515 }
516
517 // directory search
518 char* oldest_user = NULL;
519 time_t oldest_ctime = 0;
520
521 const char* tmpdirname = os::get_temp_directory();
522
523 // open the temp directory
524 DIR* tmpdirp = os::opendir(tmpdirname);
525
526 if (tmpdirp == NULL) {
527 // Cannot open the directory to get the user name, return.
528 return NULL;
529 }
530
531 // for each entry in the directory that matches the pattern hsperfdata_*,
532 // open the directory and check if the file for the given vmid exists.
533 // The file with the expected name and the latest creation date is used
534 // to determine the user name for the process id.
535 //
536 struct dirent* dentry;
537 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
538 errno = 0;
539 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
540
541 // check if the directory entry is a hsperfdata file
542 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
543 continue;
544 }
545
546 char* usrdir_name = NEW_C_HEAP_ARRAY(char,
547 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
548 strcpy(usrdir_name, tmpdirname);
549 strcat(usrdir_name, "/");
550 strcat(usrdir_name, dentry->d_name);
551
552 // open the user directory
553 DIR* subdirp = open_directory_secure(usrdir_name);
554
555 if (subdirp == NULL) {
556 FREE_C_HEAP_ARRAY(char, usrdir_name);
557 continue;
558 }
559
560 struct dirent* udentry;
561 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
562 errno = 0;
563 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
564
565 if (filename_to_pid(udentry->d_name) == vmid) {
566 struct stat statbuf;
567 int result;
568
569 char* filename = NEW_C_HEAP_ARRAY(char,
570 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
571
572 strcpy(filename, usrdir_name);
573 strcat(filename, "/");
574 strcat(filename, udentry->d_name);
575
576 // don't follow symbolic links for the file
577 RESTARTABLE(::lstat(filename, &statbuf), result);
578 if (result == OS_ERR) {
579 FREE_C_HEAP_ARRAY(char, filename);
580 continue;
581 }
582
583 // skip over files that are not regular files.
584 if (!S_ISREG(statbuf.st_mode)) {
585 FREE_C_HEAP_ARRAY(char, filename);
586 continue;
587 }
588
589 // compare and save filename with latest creation time
590 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
591
592 if (statbuf.st_ctime > oldest_ctime) {
593 char* user = strchr(dentry->d_name, '_') + 1;
594
595 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user);
596 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal);
597
598 strcpy(oldest_user, user);
599 oldest_ctime = statbuf.st_ctime;
600 }
601 }
602
603 FREE_C_HEAP_ARRAY(char, filename);
604 }
605 }
606 os::closedir(subdirp);
607 FREE_C_HEAP_ARRAY(char, udbuf);
608 FREE_C_HEAP_ARRAY(char, usrdir_name);
609 }
610 os::closedir(tmpdirp);
611 FREE_C_HEAP_ARRAY(char, tdbuf);
612
613 return(oldest_user);
614 }
615
616 // return the name of the user that owns the JVM indicated by the given vmid.
617 //
618 static char* get_user_name(int vmid, TRAPS) {
619 return get_user_name_slow(vmid, THREAD);
620 }
621
622 // return the file name of the backing store file for the named
623 // shared memory region for the given user name and vmid.
624 //
625 // the caller is expected to free the allocated memory.
626 //
627 static char* get_sharedmem_filename(const char* dirname, int vmid) {
628
629 // add 2 for the file separator and a null terminator.
630 size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
631
632 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
633 snprintf(name, nbytes, "%s/%d", dirname, vmid);
634
635 return name;
636 }
637
638
639 // remove file
640 //
641 // this method removes the file specified by the given path
642 //
643 static void remove_file(const char* path) {
644
645 int result;
646
647 // if the file is a directory, the following unlink will fail. since
648 // we don't expect to find directories in the user temp directory, we
649 // won't try to handle this situation. even if accidentially or
650 // maliciously planted, the directory's presence won't hurt anything.
651 //
652 RESTARTABLE(::unlink(path), result);
653 if (PrintMiscellaneous && Verbose && result == OS_ERR) {
654 if (errno != ENOENT) {
655 warning("Could not unlink shared memory backing"
656 " store file %s : %s\n", path, os::strerror(errno));
657 }
658 }
659 }
660
661
662 // cleanup stale shared memory resources
663 //
664 // This method attempts to remove all stale shared memory files in
665 // the named user temporary directory. It scans the named directory
666 // for files matching the pattern ^$[0-9]*$. For each file found, the
667 // process id is extracted from the file name and a test is run to
668 // determine if the process is alive. If the process is not alive,
669 // any stale file resources are removed.
670 //
671 static void cleanup_sharedmem_resources(const char* dirname) {
672
673 int saved_cwd_fd;
674 // open the directory and set the current working directory to it
675 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
676 if (dirp == NULL) {
677 // directory doesn't exist or is insecure, so there is nothing to cleanup
678 return;
679 }
680
681 // for each entry in the directory that matches the expected file
682 // name pattern, determine if the file resources are stale and if
683 // so, remove the file resources. Note, instrumented HotSpot processes
684 // for this user may start and/or terminate during this search and
685 // remove or create new files in this directory. The behavior of this
686 // loop under these conditions is dependent upon the implementation of
687 // opendir/readdir.
688 //
689 struct dirent* entry;
690 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
691
692 errno = 0;
693 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
694
695 pid_t pid = filename_to_pid(entry->d_name);
696
697 if (pid == 0) {
698
699 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
700
701 // attempt to remove all unexpected files, except "." and ".."
702 unlink(entry->d_name);
703 }
704
705 errno = 0;
706 continue;
707 }
708
709 // we now have a file name that converts to a valid integer
710 // that could represent a process id . if this process id
711 // matches the current process id or the process is not running,
712 // then remove the stale file resources.
713 //
714 // process liveness is detected by sending signal number 0 to
715 // the process id (see kill(2)). if kill determines that the
716 // process does not exist, then the file resources are removed.
717 // if kill determines that that we don't have permission to
718 // signal the process, then the file resources are assumed to
719 // be stale and are removed because the resources for such a
720 // process should be in a different user specific directory.
721 //
722 if ((pid == os::current_process_id()) ||
723 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
724
725 unlink(entry->d_name);
726 }
727 errno = 0;
728 }
729
730 // close the directory and reset the current working directory
731 close_directory_secure_cwd(dirp, saved_cwd_fd);
732
733 FREE_C_HEAP_ARRAY(char, dbuf);
734 }
735
736 // make the user specific temporary directory. Returns true if
737 // the directory exists and is secure upon return. Returns false
738 // if the directory exists but is either a symlink, is otherwise
739 // insecure, or if an error occurred.
740 //
741 static bool make_user_tmp_dir(const char* dirname) {
742
743 // create the directory with 0755 permissions. note that the directory
744 // will be owned by euid::egid, which may not be the same as uid::gid.
745 //
746 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
747 if (errno == EEXIST) {
748 // The directory already exists and was probably created by another
749 // JVM instance. However, this could also be the result of a
750 // deliberate symlink. Verify that the existing directory is safe.
751 //
752 if (!is_directory_secure(dirname)) {
753 // directory is not secure
754 if (PrintMiscellaneous && Verbose) {
755 warning("%s directory is insecure\n", dirname);
756 }
757 return false;
758 }
759 }
760 else {
761 // we encountered some other failure while attempting
762 // to create the directory
763 //
764 if (PrintMiscellaneous && Verbose) {
765 warning("could not create directory %s: %s\n",
766 dirname, os::strerror(errno));
767 }
768 return false;
769 }
770 }
771 return true;
772 }
773
774 // create the shared memory file resources
775 //
776 // This method creates the shared memory file with the given size
777 // This method also creates the user specific temporary directory, if
778 // it does not yet exist.
779 //
780 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
781
782 // make the user temporary directory
783 if (!make_user_tmp_dir(dirname)) {
784 // could not make/find the directory or the found directory
785 // was not secure
786 return -1;
787 }
788
789 int saved_cwd_fd;
790 // open the directory and set the current working directory to it
791 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
792 if (dirp == NULL) {
793 // Directory doesn't exist or is insecure, so cannot create shared
794 // memory file.
795 return -1;
796 }
797
798 // Open the filename in the current directory.
799 // Cannot use O_TRUNC here; truncation of an existing file has to happen
800 // after the is_file_secure() check below.
801 int result;
802 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result);
803 if (result == OS_ERR) {
804 if (PrintMiscellaneous && Verbose) {
805 if (errno == ELOOP) {
806 warning("file %s is a symlink and is not secure\n", filename);
807 } else {
808 warning("could not create file %s: %s\n", filename, os::strerror(errno));
809 }
810 }
811 // close the directory and reset the current working directory
812 close_directory_secure_cwd(dirp, saved_cwd_fd);
813
814 return -1;
815 }
816 // close the directory and reset the current working directory
817 close_directory_secure_cwd(dirp, saved_cwd_fd);
818
819 // save the file descriptor
820 int fd = result;
821
822 // check to see if the file is secure
823 if (!is_file_secure(fd, filename)) {
824 ::close(fd);
825 return -1;
826 }
827
828 // truncate the file to get rid of any existing data
829 RESTARTABLE(::ftruncate(fd, (off_t)0), result);
830 if (result == OS_ERR) {
831 if (PrintMiscellaneous && Verbose) {
832 warning("could not truncate shared memory file: %s\n", os::strerror(errno));
833 }
834 ::close(fd);
835 return -1;
836 }
837 // set the file size
838 RESTARTABLE(::ftruncate(fd, (off_t)size), result);
839 if (result == OS_ERR) {
840 if (PrintMiscellaneous && Verbose) {
841 warning("could not set shared memory file size: %s\n", os::strerror(errno));
842 }
843 ::close(fd);
844 return -1;
845 }
846
847 // Verify that we have enough disk space for this file.
848 // We'll get random SIGBUS crashes on memory accesses if
849 // we don't.
850
851 for (size_t seekpos = 0; seekpos < size; seekpos += os::vm_page_size()) {
852 int zero_int = 0;
853 result = (int)os::seek_to_file_offset(fd, (jlong)(seekpos));
854 if (result == -1 ) break;
855 RESTARTABLE(::write(fd, &zero_int, 1), result);
856 if (result != 1) {
857 if (errno == ENOSPC) {
858 warning("Insufficient space for shared memory file:\n %s\nTry using the -Djava.io.tmpdir= option to select an alternate temp location.\n", filename);
859 }
860 break;
861 }
862 }
863
864 if (result != -1) {
865 return fd;
866 } else {
867 ::close(fd);
868 return -1;
869 }
870 }
871
872 // open the shared memory file for the given user and vmid. returns
873 // the file descriptor for the open file or -1 if the file could not
874 // be opened.
875 //
876 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
877
878 // open the file
879 int result;
880 RESTARTABLE(::open(filename, oflags), result);
881 if (result == OS_ERR) {
882 if (errno == ENOENT) {
883 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
884 "Process not found", OS_ERR);
885 }
886 else if (errno == EACCES) {
887 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
888 "Permission denied", OS_ERR);
889 }
890 else {
891 THROW_MSG_(vmSymbols::java_io_IOException(),
892 os::strerror(errno), OS_ERR);
893 }
894 }
895 int fd = result;
896
897 // check to see if the file is secure
898 if (!is_file_secure(fd, filename)) {
899 ::close(fd);
900 return -1;
901 }
902
903 return fd;
904 }
905
906 // create a named shared memory region. returns the address of the
907 // memory region on success or NULL on failure. A return value of
908 // NULL will ultimately disable the shared memory feature.
909 //
910 // On BSD, the name space for shared memory objects
911 // is the file system name space.
912 //
913 // A monitoring application attaching to a JVM does not need to know
914 // the file system name of the shared memory object. However, it may
915 // be convenient for applications to discover the existence of newly
916 // created and terminating JVMs by watching the file system name space
917 // for files being created or removed.
918 //
919 static char* mmap_create_shared(size_t size) {
920
921 int result;
922 int fd;
923 char* mapAddress;
924
925 int vmid = os::current_process_id();
926
927 char* user_name = get_user_name(geteuid());
928
929 if (user_name == NULL)
930 return NULL;
931
932 char* dirname = get_user_tmp_dir(user_name);
933 char* filename = get_sharedmem_filename(dirname, vmid);
934
935 // get the short filename
936 char* short_filename = strrchr(filename, '/');
937 if (short_filename == NULL) {
938 short_filename = filename;
939 } else {
940 short_filename++;
941 }
942
943 // cleanup any stale shared memory files
944 cleanup_sharedmem_resources(dirname);
945
946 assert(((size > 0) && (size % os::vm_page_size() == 0)),
947 "unexpected PerfMemory region size");
948
949 fd = create_sharedmem_resources(dirname, short_filename, size);
950
951 FREE_C_HEAP_ARRAY(char, user_name);
952 FREE_C_HEAP_ARRAY(char, dirname);
953
954 if (fd == -1) {
955 FREE_C_HEAP_ARRAY(char, filename);
956 return NULL;
957 }
958
959 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
960
961 result = ::close(fd);
962 assert(result != OS_ERR, "could not close file");
963
964 if (mapAddress == MAP_FAILED) {
965 if (PrintMiscellaneous && Verbose) {
966 warning("mmap failed - %s\n", os::strerror(errno));
967 }
968 remove_file(filename);
969 FREE_C_HEAP_ARRAY(char, filename);
970 return NULL;
971 }
972
973 // save the file name for use in delete_shared_memory()
974 backing_store_file_name = filename;
975
976 // clear the shared memory region
977 (void)::memset((void*) mapAddress, 0, size);
978
979 // it does not go through os api, the operation has to record from here
980 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal);
981
982 return mapAddress;
983 }
984
985 // release a named shared memory region
986 //
987 static void unmap_shared(char* addr, size_t bytes) {
988 os::release_memory(addr, bytes);
989 }
990
991 // create the PerfData memory region in shared memory.
992 //
993 static char* create_shared_memory(size_t size) {
994
995 // create the shared memory region.
996 return mmap_create_shared(size);
997 }
998
999 // delete the shared PerfData memory region
1000 //
1001 static void delete_shared_memory(char* addr, size_t size) {
1002
1003 // cleanup the persistent shared memory resources. since DestroyJavaVM does
1004 // not support unloading of the JVM, unmapping of the memory resource is
1005 // not performed. The memory will be reclaimed by the OS upon termination of
1006 // the process. The backing store file is deleted from the file system.
1007
1008 assert(!PerfDisableSharedMem, "shouldn't be here");
1009
1010 if (backing_store_file_name != NULL) {
1011 remove_file(backing_store_file_name);
1012 // Don't.. Free heap memory could deadlock os::abort() if it is called
1013 // from signal handler. OS will reclaim the heap memory.
1014 // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
1015 backing_store_file_name = NULL;
1016 }
1017 }
1018
1019 // return the size of the file for the given file descriptor
1020 // or 0 if it is not a valid size for a shared memory file
1021 //
1022 static size_t sharedmem_filesize(int fd, TRAPS) {
1023
1024 struct stat statbuf;
1025 int result;
1026
1027 RESTARTABLE(::fstat(fd, &statbuf), result);
1028 if (result == OS_ERR) {
1029 if (PrintMiscellaneous && Verbose) {
1030 warning("fstat failed: %s\n", os::strerror(errno));
1031 }
1032 THROW_MSG_0(vmSymbols::java_io_IOException(),
1033 "Could not determine PerfMemory size");
1034 }
1035
1036 if ((statbuf.st_size == 0) ||
1037 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
1038 THROW_MSG_0(vmSymbols::java_lang_Exception(),
1039 "Invalid PerfMemory size");
1040 }
1041
1042 return (size_t)statbuf.st_size;
1043 }
1044
1045 // attach to a named shared memory region.
1046 //
1047 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
1048
1049 char* mapAddress;
1050 int result;
1051 int fd;
1052 size_t size = 0;
1053 const char* luser = NULL;
1054
1055 int mmap_prot;
1056 int file_flags;
1057
1058 ResourceMark rm;
1059
1060 // map the high level access mode to the appropriate permission
1061 // constructs for the file and the shared memory mapping.
1062 if (mode == PerfMemory::PERF_MODE_RO) {
1063 mmap_prot = PROT_READ;
1064 file_flags = O_RDONLY | O_NOFOLLOW;
1065 }
1066 else if (mode == PerfMemory::PERF_MODE_RW) {
1067 #ifdef LATER
1068 mmap_prot = PROT_READ | PROT_WRITE;
1069 file_flags = O_RDWR | O_NOFOLLOW;
1070 #else
1071 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1072 "Unsupported access mode");
1073 #endif
1074 }
1075 else {
1076 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1077 "Illegal access mode");
1078 }
1079
1080 if (user == NULL || strlen(user) == 0) {
1081 luser = get_user_name(vmid, CHECK);
1082 }
1083 else {
1084 luser = user;
1085 }
1086
1087 if (luser == NULL) {
1088 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1089 "Could not map vmid to user Name");
1090 }
1091
1092 char* dirname = get_user_tmp_dir(luser);
1093
1094 // since we don't follow symbolic links when creating the backing
1095 // store file, we don't follow them when attaching either.
1096 //
1097 if (!is_directory_secure(dirname)) {
1098 FREE_C_HEAP_ARRAY(char, dirname);
1099 if (luser != user) {
1100 FREE_C_HEAP_ARRAY(char, luser);
1101 }
1102 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1103 "Process not found");
1104 }
1105
1106 char* filename = get_sharedmem_filename(dirname, vmid);
1107
1108 // copy heap memory to resource memory. the open_sharedmem_file
1109 // method below need to use the filename, but could throw an
1110 // exception. using a resource array prevents the leak that
1111 // would otherwise occur.
1112 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
1113 strcpy(rfilename, filename);
1114
1115 // free the c heap resources that are no longer needed
1116 if (luser != user) FREE_C_HEAP_ARRAY(char, luser);
1117 FREE_C_HEAP_ARRAY(char, dirname);
1118 FREE_C_HEAP_ARRAY(char, filename);
1119
1120 // open the shared memory file for the give vmid
1121 fd = open_sharedmem_file(rfilename, file_flags, CHECK);
1122 assert(fd != OS_ERR, "unexpected value");
1123
1124 if (*sizep == 0) {
1125 size = sharedmem_filesize(fd, CHECK);
1126 } else {
1127 size = *sizep;
1128 }
1129
1130 assert(size > 0, "unexpected size <= 0");
1131
1132 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
1133
1134 // attempt to close the file - restart if it gets interrupted,
1135 // but ignore other failures
1136 result = ::close(fd);
1137 assert(result != OS_ERR, "could not close file");
1138
1139 if (mapAddress == MAP_FAILED) {
1140 if (PrintMiscellaneous && Verbose) {
1141 warning("mmap failed: %s\n", os::strerror(errno));
1142 }
1143 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
1144 "Could not map PerfMemory");
1145 }
1146
1147 // it does not go through os api, the operation has to record from here
1148 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal);
1149
1150 *addr = mapAddress;
1151 *sizep = size;
1152
1153 if (PerfTraceMemOps) {
1154 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
1155 INTPTR_FORMAT "\n", size, vmid, p2i((void*)mapAddress));
1156 }
1157 }
1158
1159
1160
1161
1162 // create the PerfData memory region
1163 //
1164 // This method creates the memory region used to store performance
1165 // data for the JVM. The memory may be created in standard or
1166 // shared memory.
1167 //
1168 void PerfMemory::create_memory_region(size_t size) {
1169
1170 if (PerfDisableSharedMem) {
1171 // do not share the memory for the performance data.
1172 _start = create_standard_memory(size);
1173 }
1174 else {
1175 _start = create_shared_memory(size);
1176 if (_start == NULL) {
1177
1178 // creation of the shared memory region failed, attempt
1179 // to create a contiguous, non-shared memory region instead.
1180 //
1181 if (PrintMiscellaneous && Verbose) {
1182 warning("Reverting to non-shared PerfMemory region.\n");
1183 }
1184 PerfDisableSharedMem = true;
1185 _start = create_standard_memory(size);
1186 }
1187 }
1188
1189 if (_start != NULL) _capacity = size;
1190
1191 }
1192
1193 // delete the PerfData memory region
1194 //
1195 // This method deletes the memory region used to store performance
1196 // data for the JVM. The memory region indicated by the <address, size>
1197 // tuple will be inaccessible after a call to this method.
1198 //
1199 void PerfMemory::delete_memory_region() {
1200
1201 assert((start() != NULL && capacity() > 0), "verify proper state");
1202
1203 // If user specifies PerfDataSaveFile, it will save the performance data
1204 // to the specified file name no matter whether PerfDataSaveToFile is specified
1205 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
1206 // -XX:+PerfDataSaveToFile.
1207 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
1208 save_memory_to_file(start(), capacity());
1209 }
1210
1211 if (PerfDisableSharedMem) {
1212 delete_standard_memory(start(), capacity());
1213 }
1214 else {
1215 delete_shared_memory(start(), capacity());
1216 }
1217 }
1218
1219 // attach to the PerfData memory region for another JVM
1220 //
1221 // This method returns an <address, size> tuple that points to
1222 // a memory buffer that is kept reasonably synchronized with
1223 // the PerfData memory region for the indicated JVM. This
1224 // buffer may be kept in synchronization via shared memory
1225 // or some other mechanism that keeps the buffer updated.
1226 //
1227 // If the JVM chooses not to support the attachability feature,
1228 // this method should throw an UnsupportedOperation exception.
1229 //
1230 // This implementation utilizes named shared memory to map
1231 // the indicated process's PerfData memory region into this JVMs
1232 // address space.
1233 //
1234 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
1235
1236 if (vmid == 0 || vmid == os::current_process_id()) {
1237 *addrp = start();
1238 *sizep = capacity();
1239 return;
1240 }
1241
1242 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
1243 }
1244
1245 // detach from the PerfData memory region of another JVM
1246 //
1247 // This method detaches the PerfData memory region of another
1248 // JVM, specified as an <address, size> tuple of a buffer
1249 // in this process's address space. This method may perform
1250 // arbitrary actions to accomplish the detachment. The memory
1251 // region specified by <address, size> will be inaccessible after
1252 // a call to this method.
1253 //
1254 // If the JVM chooses not to support the attachability feature,
1255 // this method should throw an UnsupportedOperation exception.
1256 //
1257 // This implementation utilizes named shared memory to detach
1258 // the indicated process's PerfData memory region from this
1259 // process's address space.
1260 //
1261 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1262
1263 assert(addr != 0, "address sanity check");
1264 assert(bytes > 0, "capacity sanity check");
1265
1266 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1267 // prevent accidental detachment of this process's PerfMemory region
1268 return;
1269 }
1270
1271 unmap_shared(addr, bytes);
1272 }