1 /*
2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/vmSymbols.hpp"
27 #include "logging/log.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "os_bsd.inline.hpp"
32 #include "runtime/handles.inline.hpp"
33 #include "runtime/os.hpp"
34 #include "runtime/perfMemory.hpp"
35 #include "services/memTracker.hpp"
36 #include "utilities/exceptions.hpp"
37
38 // put OS-includes here
39 # include <sys/types.h>
40 # include <sys/mman.h>
41 # include <errno.h>
42 # include <stdio.h>
43 # include <unistd.h>
44 # include <sys/stat.h>
45 # include <signal.h>
46 # include <pwd.h>
47
48 static char* backing_store_file_name = NULL; // name of the backing store
49 // file, if successfully created.
50
51 // Standard Memory Implementation Details
52
53 // create the PerfData memory region in standard memory.
54 //
55 static char* create_standard_memory(size_t size) {
56
57 // allocate an aligned chuck of memory
58 char* mapAddress = os::reserve_memory(size);
59
60 if (mapAddress == NULL) {
61 return NULL;
62 }
63
64 // commit memory
65 if (!os::commit_memory(mapAddress, size, !ExecMem)) {
66 if (PrintMiscellaneous && Verbose) {
67 warning("Could not commit PerfData memory\n");
68 }
69 os::release_memory(mapAddress, size);
70 return NULL;
71 }
72
73 return mapAddress;
74 }
75
76 // delete the PerfData memory region
77 //
78 static void delete_standard_memory(char* addr, size_t size) {
79
80 // there are no persistent external resources to cleanup for standard
81 // memory. since DestroyJavaVM does not support unloading of the JVM,
82 // cleanup of the memory resource is not performed. The memory will be
83 // reclaimed by the OS upon termination of the process.
84 //
85 return;
86 }
87
88 // save the specified memory region to the given file
89 //
90 // Note: this function might be called from signal handler (by os::abort()),
91 // don't allocate heap memory.
92 //
93 static void save_memory_to_file(char* addr, size_t size) {
94
95 const char* destfile = PerfMemory::get_perfdata_file_path();
96 assert(destfile[0] != '\0', "invalid PerfData file path");
97
98 int result;
99
100 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE),
101 result);;
102 if (result == OS_ERR) {
103 if (PrintMiscellaneous && Verbose) {
104 warning("Could not create Perfdata save file: %s: %s\n",
105 destfile, os::strerror(errno));
106 }
107 } else {
108 int fd = result;
109
110 for (size_t remaining = size; remaining > 0;) {
111
112 RESTARTABLE(::write(fd, addr, remaining), result);
113 if (result == OS_ERR) {
114 if (PrintMiscellaneous && Verbose) {
115 warning("Could not write Perfdata save file: %s: %s\n",
116 destfile, os::strerror(errno));
117 }
118 break;
119 }
120
121 remaining -= (size_t)result;
122 addr += result;
123 }
124
125 result = ::close(fd);
126 if (PrintMiscellaneous && Verbose) {
127 if (result == OS_ERR) {
128 warning("Could not close %s: %s\n", destfile, os::strerror(errno));
129 }
130 }
131 }
132 FREE_C_HEAP_ARRAY(char, destfile);
133 }
134
135
136 // Shared Memory Implementation Details
137
138 // Note: the solaris and bsd shared memory implementation uses the mmap
139 // interface with a backing store file to implement named shared memory.
140 // Using the file system as the name space for shared memory allows a
141 // common name space to be supported across a variety of platforms. It
142 // also provides a name space that Java applications can deal with through
143 // simple file apis.
144 //
145 // The solaris and bsd implementations store the backing store file in
146 // a user specific temporary directory located in the /tmp file system,
147 // which is always a local file system and is sometimes a RAM based file
148 // system.
149
150 // return the user specific temporary directory name.
151 //
152 // the caller is expected to free the allocated memory.
153 //
154 static char* get_user_tmp_dir(const char* user) {
155
156 const char* tmpdir = os::get_temp_directory();
157 const char* perfdir = PERFDATA_NAME;
158 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3;
159 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
160
161 // construct the path name to user specific tmp directory
162 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user);
163
164 return dirname;
165 }
166
167 // convert the given file name into a process id. if the file
168 // does not meet the file naming constraints, return 0.
169 //
170 static pid_t filename_to_pid(const char* filename) {
171
172 // a filename that doesn't begin with a digit is not a
173 // candidate for conversion.
174 //
175 if (!isdigit(*filename)) {
176 return 0;
177 }
178
179 // check if file name can be converted to an integer without
180 // any leftover characters.
181 //
182 char* remainder = NULL;
183 errno = 0;
184 pid_t pid = (pid_t)strtol(filename, &remainder, 10);
185
186 if (errno != 0) {
187 return 0;
188 }
189
190 // check for left over characters. If any, then the filename is
191 // not a candidate for conversion.
192 //
193 if (remainder != NULL && *remainder != '\0') {
194 return 0;
195 }
196
197 // successful conversion, return the pid
198 return pid;
199 }
200
201
202 // Check if the given statbuf is considered a secure directory for
203 // the backing store files. Returns true if the directory is considered
204 // a secure location. Returns false if the statbuf is a symbolic link or
205 // if an error occurred.
206 //
207 static bool is_statbuf_secure(struct stat *statp) {
208 if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) {
209 // The path represents a link or some non-directory file type,
210 // which is not what we expected. Declare it insecure.
211 //
212 return false;
213 }
214 // We have an existing directory, check if the permissions are safe.
215 //
216 if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) {
217 // The directory is open for writing and could be subjected
218 // to a symlink or a hard link attack. Declare it insecure.
219 //
220 return false;
221 }
222 // If user is not root then see if the uid of the directory matches the effective uid of the process.
223 uid_t euid = geteuid();
224 if ((euid != 0) && (statp->st_uid != euid)) {
225 // The directory was not created by this user, declare it insecure.
226 //
227 return false;
228 }
229 return true;
230 }
231
232
233 // Check if the given path is considered a secure directory for
234 // the backing store files. Returns true if the directory exists
235 // and is considered a secure location. Returns false if the path
236 // is a symbolic link or if an error occurred.
237 //
238 static bool is_directory_secure(const char* path) {
239 struct stat statbuf;
240 int result = 0;
241
242 RESTARTABLE(::lstat(path, &statbuf), result);
243 if (result == OS_ERR) {
244 return false;
245 }
246
247 // The path exists, see if it is secure.
248 return is_statbuf_secure(&statbuf);
249 }
250
251
252 // Check if the given directory file descriptor is considered a secure
253 // directory for the backing store files. Returns true if the directory
254 // exists and is considered a secure location. Returns false if the path
255 // is a symbolic link or if an error occurred.
256 //
257 static bool is_dirfd_secure(int dir_fd) {
258 struct stat statbuf;
259 int result = 0;
260
261 RESTARTABLE(::fstat(dir_fd, &statbuf), result);
262 if (result == OS_ERR) {
263 return false;
264 }
265
266 // The path exists, now check its mode.
267 return is_statbuf_secure(&statbuf);
268 }
269
270
271 // Check to make sure fd1 and fd2 are referencing the same file system object.
272 //
273 static bool is_same_fsobject(int fd1, int fd2) {
274 struct stat statbuf1;
275 struct stat statbuf2;
276 int result = 0;
277
278 RESTARTABLE(::fstat(fd1, &statbuf1), result);
279 if (result == OS_ERR) {
280 return false;
281 }
282 RESTARTABLE(::fstat(fd2, &statbuf2), result);
283 if (result == OS_ERR) {
284 return false;
285 }
286
287 if ((statbuf1.st_ino == statbuf2.st_ino) &&
288 (statbuf1.st_dev == statbuf2.st_dev)) {
289 return true;
290 } else {
291 return false;
292 }
293 }
294
295
296 // Open the directory of the given path and validate it.
297 // Return a DIR * of the open directory.
298 //
299 static DIR *open_directory_secure(const char* dirname) {
300 // Open the directory using open() so that it can be verified
301 // to be secure by calling is_dirfd_secure(), opendir() and then check
302 // to see if they are the same file system object. This method does not
303 // introduce a window of opportunity for the directory to be attacked that
304 // calling opendir() and is_directory_secure() does.
305 int result;
306 DIR *dirp = NULL;
307 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result);
308 if (result == OS_ERR) {
309 // Directory doesn't exist or is a symlink, so there is nothing to cleanup.
310 if (PrintMiscellaneous && Verbose) {
311 if (errno == ELOOP) {
312 warning("directory %s is a symlink and is not secure\n", dirname);
313 } else {
314 warning("could not open directory %s: %s\n", dirname, os::strerror(errno));
315 }
316 }
317 return dirp;
318 }
319 int fd = result;
320
321 // Determine if the open directory is secure.
322 if (!is_dirfd_secure(fd)) {
323 // The directory is not a secure directory.
324 os::close(fd);
325 return dirp;
326 }
327
328 // Open the directory.
329 dirp = ::opendir(dirname);
330 if (dirp == NULL) {
331 // The directory doesn't exist, close fd and return.
332 os::close(fd);
333 return dirp;
334 }
335
336 // Check to make sure fd and dirp are referencing the same file system object.
337 if (!is_same_fsobject(fd, dirfd(dirp))) {
338 // The directory is not secure.
339 os::close(fd);
340 os::closedir(dirp);
341 dirp = NULL;
342 return dirp;
343 }
344
345 // Close initial open now that we know directory is secure
346 os::close(fd);
347
348 return dirp;
349 }
350
351 // NOTE: The code below uses fchdir(), open() and unlink() because
352 // fdopendir(), openat() and unlinkat() are not supported on all
353 // versions. Once the support for fdopendir(), openat() and unlinkat()
354 // is available on all supported versions the code can be changed
355 // to use these functions.
356
357 // Open the directory of the given path, validate it and set the
358 // current working directory to it.
359 // Return a DIR * of the open directory and the saved cwd fd.
360 //
361 static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) {
362
363 // Open the directory.
364 DIR* dirp = open_directory_secure(dirname);
365 if (dirp == NULL) {
366 // Directory doesn't exist or is insecure, so there is nothing to cleanup.
367 return dirp;
368 }
369 int fd = dirfd(dirp);
370
371 // Open a fd to the cwd and save it off.
372 int result;
373 RESTARTABLE(::open(".", O_RDONLY), result);
374 if (result == OS_ERR) {
375 *saved_cwd_fd = -1;
376 } else {
377 *saved_cwd_fd = result;
378 }
379
380 // Set the current directory to dirname by using the fd of the directory and
381 // handle errors, otherwise shared memory files will be created in cwd.
382 result = fchdir(fd);
383 if (result == OS_ERR) {
384 if (PrintMiscellaneous && Verbose) {
385 warning("could not change to directory %s", dirname);
386 }
387 if (*saved_cwd_fd != -1) {
388 ::close(*saved_cwd_fd);
389 *saved_cwd_fd = -1;
390 }
391 // Close the directory.
392 os::closedir(dirp);
393 return NULL;
394 } else {
395 return dirp;
396 }
397 }
398
399 // Close the directory and restore the current working directory.
400 //
401 static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) {
402
403 int result;
404 // If we have a saved cwd change back to it and close the fd.
405 if (saved_cwd_fd != -1) {
406 result = fchdir(saved_cwd_fd);
407 ::close(saved_cwd_fd);
408 }
409
410 // Close the directory.
411 os::closedir(dirp);
412 }
413
414 // Check if the given file descriptor is considered a secure.
415 //
416 static bool is_file_secure(int fd, const char *filename) {
417
418 int result;
419 struct stat statbuf;
420
421 // Determine if the file is secure.
422 RESTARTABLE(::fstat(fd, &statbuf), result);
423 if (result == OS_ERR) {
424 if (PrintMiscellaneous && Verbose) {
425 warning("fstat failed on %s: %s\n", filename, os::strerror(errno));
426 }
427 return false;
428 }
429 if (statbuf.st_nlink > 1) {
430 // A file with multiple links is not expected.
431 if (PrintMiscellaneous && Verbose) {
432 warning("file %s has multiple links\n", filename);
433 }
434 return false;
435 }
436 return true;
437 }
438
439 // return the user name for the given user id
440 //
441 // the caller is expected to free the allocated memory.
442 //
443 static char* get_user_name(uid_t uid) {
444
445 struct passwd pwent;
446
447 // determine the max pwbuf size from sysconf, and hardcode
448 // a default if this not available through sysconf.
449 //
450 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
451 if (bufsize == -1)
452 bufsize = 1024;
453
454 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
455
456 // POSIX interface to getpwuid_r is used on LINUX
457 struct passwd* p;
458 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);
459
460 if (result != 0 || p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {
461 if (PrintMiscellaneous && Verbose) {
462 if (result != 0) {
463 warning("Could not retrieve passwd entry: %s\n",
464 os::strerror(result));
465 }
466 else if (p == NULL) {
467 // this check is added to protect against an observed problem
468 // with getpwuid_r() on RedHat 9 where getpwuid_r returns 0,
469 // indicating success, but has p == NULL. This was observed when
470 // inserting a file descriptor exhaustion fault prior to the call
471 // getpwuid_r() call. In this case, error is set to the appropriate
472 // error condition, but this is undocumented behavior. This check
473 // is safe under any condition, but the use of errno in the output
474 // message may result in an erroneous message.
475 // Bug Id 89052 was opened with RedHat.
476 //
477 warning("Could not retrieve passwd entry: %s\n",
478 os::strerror(errno));
479 }
480 else {
481 warning("Could not determine user name: %s\n",
482 p->pw_name == NULL ? "pw_name = NULL" :
483 "pw_name zero length");
484 }
485 }
486 FREE_C_HEAP_ARRAY(char, pwbuf);
487 return NULL;
488 }
489
490 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal);
491 strcpy(user_name, p->pw_name);
492
493 FREE_C_HEAP_ARRAY(char, pwbuf);
494 return user_name;
495 }
496
497 // return the name of the user that owns the process identified by vmid.
498 //
499 // This method uses a slow directory search algorithm to find the backing
500 // store file for the specified vmid and returns the user name, as determined
501 // by the user name suffix of the hsperfdata_<username> directory name.
502 //
503 // the caller is expected to free the allocated memory.
504 //
505 static char* get_user_name_slow(int vmid, TRAPS) {
506
507 // short circuit the directory search if the process doesn't even exist.
508 if (kill(vmid, 0) == OS_ERR) {
509 if (errno == ESRCH) {
510 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
511 "Process not found");
512 }
513 else /* EPERM */ {
514 THROW_MSG_0(vmSymbols::java_io_IOException(), os::strerror(errno));
515 }
516 }
517
518 // directory search
519 char* oldest_user = NULL;
520 time_t oldest_ctime = 0;
521
522 const char* tmpdirname = os::get_temp_directory();
523
524 // open the temp directory
525 DIR* tmpdirp = os::opendir(tmpdirname);
526
527 if (tmpdirp == NULL) {
528 // Cannot open the directory to get the user name, return.
529 return NULL;
530 }
531
532 // for each entry in the directory that matches the pattern hsperfdata_*,
533 // open the directory and check if the file for the given vmid exists.
534 // The file with the expected name and the latest creation date is used
535 // to determine the user name for the process id.
536 //
537 struct dirent* dentry;
538 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
539 errno = 0;
540 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
541
542 // check if the directory entry is a hsperfdata file
543 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
544 continue;
545 }
546
547 char* usrdir_name = NEW_C_HEAP_ARRAY(char,
548 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
549 strcpy(usrdir_name, tmpdirname);
550 strcat(usrdir_name, "/");
551 strcat(usrdir_name, dentry->d_name);
552
553 // open the user directory
554 DIR* subdirp = open_directory_secure(usrdir_name);
555
556 if (subdirp == NULL) {
557 FREE_C_HEAP_ARRAY(char, usrdir_name);
558 continue;
559 }
560
561 struct dirent* udentry;
562 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
563 errno = 0;
564 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
565
566 if (filename_to_pid(udentry->d_name) == vmid) {
567 struct stat statbuf;
568 int result;
569
570 char* filename = NEW_C_HEAP_ARRAY(char,
571 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
572
573 strcpy(filename, usrdir_name);
574 strcat(filename, "/");
575 strcat(filename, udentry->d_name);
576
577 // don't follow symbolic links for the file
578 RESTARTABLE(::lstat(filename, &statbuf), result);
579 if (result == OS_ERR) {
580 FREE_C_HEAP_ARRAY(char, filename);
581 continue;
582 }
583
584 // skip over files that are not regular files.
585 if (!S_ISREG(statbuf.st_mode)) {
586 FREE_C_HEAP_ARRAY(char, filename);
587 continue;
588 }
589
590 // compare and save filename with latest creation time
591 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
592
593 if (statbuf.st_ctime > oldest_ctime) {
594 char* user = strchr(dentry->d_name, '_') + 1;
595
596 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user);
597 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal);
598
599 strcpy(oldest_user, user);
600 oldest_ctime = statbuf.st_ctime;
601 }
602 }
603
604 FREE_C_HEAP_ARRAY(char, filename);
605 }
606 }
607 os::closedir(subdirp);
608 FREE_C_HEAP_ARRAY(char, udbuf);
609 FREE_C_HEAP_ARRAY(char, usrdir_name);
610 }
611 os::closedir(tmpdirp);
612 FREE_C_HEAP_ARRAY(char, tdbuf);
613
614 return(oldest_user);
615 }
616
617 // return the name of the user that owns the JVM indicated by the given vmid.
618 //
619 static char* get_user_name(int vmid, TRAPS) {
620 return get_user_name_slow(vmid, THREAD);
621 }
622
623 // return the file name of the backing store file for the named
624 // shared memory region for the given user name and vmid.
625 //
626 // the caller is expected to free the allocated memory.
627 //
628 static char* get_sharedmem_filename(const char* dirname, int vmid) {
629
630 // add 2 for the file separator and a null terminator.
631 size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
632
633 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
634 snprintf(name, nbytes, "%s/%d", dirname, vmid);
635
636 return name;
637 }
638
639
640 // remove file
641 //
642 // this method removes the file specified by the given path
643 //
644 static void remove_file(const char* path) {
645
646 int result;
647
648 // if the file is a directory, the following unlink will fail. since
649 // we don't expect to find directories in the user temp directory, we
650 // won't try to handle this situation. even if accidentially or
651 // maliciously planted, the directory's presence won't hurt anything.
652 //
653 RESTARTABLE(::unlink(path), result);
654 if (PrintMiscellaneous && Verbose && result == OS_ERR) {
655 if (errno != ENOENT) {
656 warning("Could not unlink shared memory backing"
657 " store file %s : %s\n", path, os::strerror(errno));
658 }
659 }
660 }
661
662
663 // cleanup stale shared memory resources
664 //
665 // This method attempts to remove all stale shared memory files in
666 // the named user temporary directory. It scans the named directory
667 // for files matching the pattern ^$[0-9]*$. For each file found, the
668 // process id is extracted from the file name and a test is run to
669 // determine if the process is alive. If the process is not alive,
670 // any stale file resources are removed.
671 //
672 static void cleanup_sharedmem_resources(const char* dirname) {
673
674 int saved_cwd_fd;
675 // open the directory and set the current working directory to it
676 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
677 if (dirp == NULL) {
678 // directory doesn't exist or is insecure, so there is nothing to cleanup
679 return;
680 }
681
682 // for each entry in the directory that matches the expected file
683 // name pattern, determine if the file resources are stale and if
684 // so, remove the file resources. Note, instrumented HotSpot processes
685 // for this user may start and/or terminate during this search and
686 // remove or create new files in this directory. The behavior of this
687 // loop under these conditions is dependent upon the implementation of
688 // opendir/readdir.
689 //
690 struct dirent* entry;
691 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
692
693 errno = 0;
694 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
695
696 pid_t pid = filename_to_pid(entry->d_name);
697
698 if (pid == 0) {
699
700 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
701
702 // attempt to remove all unexpected files, except "." and ".."
703 unlink(entry->d_name);
704 }
705
706 errno = 0;
707 continue;
708 }
709
710 // we now have a file name that converts to a valid integer
711 // that could represent a process id . if this process id
712 // matches the current process id or the process is not running,
713 // then remove the stale file resources.
714 //
715 // process liveness is detected by sending signal number 0 to
716 // the process id (see kill(2)). if kill determines that the
717 // process does not exist, then the file resources are removed.
718 // if kill determines that that we don't have permission to
719 // signal the process, then the file resources are assumed to
720 // be stale and are removed because the resources for such a
721 // process should be in a different user specific directory.
722 //
723 if ((pid == os::current_process_id()) ||
724 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
725
726 unlink(entry->d_name);
727 }
728 errno = 0;
729 }
730
731 // close the directory and reset the current working directory
732 close_directory_secure_cwd(dirp, saved_cwd_fd);
733
734 FREE_C_HEAP_ARRAY(char, dbuf);
735 }
736
737 // make the user specific temporary directory. Returns true if
738 // the directory exists and is secure upon return. Returns false
739 // if the directory exists but is either a symlink, is otherwise
740 // insecure, or if an error occurred.
741 //
742 static bool make_user_tmp_dir(const char* dirname) {
743
744 // create the directory with 0755 permissions. note that the directory
745 // will be owned by euid::egid, which may not be the same as uid::gid.
746 //
747 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
748 if (errno == EEXIST) {
749 // The directory already exists and was probably created by another
750 // JVM instance. However, this could also be the result of a
751 // deliberate symlink. Verify that the existing directory is safe.
752 //
753 if (!is_directory_secure(dirname)) {
754 // directory is not secure
755 if (PrintMiscellaneous && Verbose) {
756 warning("%s directory is insecure\n", dirname);
757 }
758 return false;
759 }
760 }
761 else {
762 // we encountered some other failure while attempting
763 // to create the directory
764 //
765 if (PrintMiscellaneous && Verbose) {
766 warning("could not create directory %s: %s\n",
767 dirname, os::strerror(errno));
768 }
769 return false;
770 }
771 }
772 return true;
773 }
774
775 // create the shared memory file resources
776 //
777 // This method creates the shared memory file with the given size
778 // This method also creates the user specific temporary directory, if
779 // it does not yet exist.
780 //
781 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
782
783 // make the user temporary directory
784 if (!make_user_tmp_dir(dirname)) {
785 // could not make/find the directory or the found directory
786 // was not secure
787 return -1;
788 }
789
790 int saved_cwd_fd;
791 // open the directory and set the current working directory to it
792 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
793 if (dirp == NULL) {
794 // Directory doesn't exist or is insecure, so cannot create shared
795 // memory file.
796 return -1;
797 }
798
799 // Open the filename in the current directory.
800 // Cannot use O_TRUNC here; truncation of an existing file has to happen
801 // after the is_file_secure() check below.
802 int result;
803 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result);
804 if (result == OS_ERR) {
805 if (PrintMiscellaneous && Verbose) {
806 if (errno == ELOOP) {
807 warning("file %s is a symlink and is not secure\n", filename);
808 } else {
809 warning("could not create file %s: %s\n", filename, os::strerror(errno));
810 }
811 }
812 // close the directory and reset the current working directory
813 close_directory_secure_cwd(dirp, saved_cwd_fd);
814
815 return -1;
816 }
817 // close the directory and reset the current working directory
818 close_directory_secure_cwd(dirp, saved_cwd_fd);
819
820 // save the file descriptor
821 int fd = result;
822
823 // check to see if the file is secure
824 if (!is_file_secure(fd, filename)) {
825 ::close(fd);
826 return -1;
827 }
828
829 // truncate the file to get rid of any existing data
830 RESTARTABLE(::ftruncate(fd, (off_t)0), result);
831 if (result == OS_ERR) {
832 if (PrintMiscellaneous && Verbose) {
833 warning("could not truncate shared memory file: %s\n", os::strerror(errno));
834 }
835 ::close(fd);
836 return -1;
837 }
838 // set the file size
839 RESTARTABLE(::ftruncate(fd, (off_t)size), result);
840 if (result == OS_ERR) {
841 if (PrintMiscellaneous && Verbose) {
842 warning("could not set shared memory file size: %s\n", os::strerror(errno));
843 }
844 ::close(fd);
845 return -1;
846 }
847
848 // Verify that we have enough disk space for this file.
849 // We'll get random SIGBUS crashes on memory accesses if
850 // we don't.
851
852 for (size_t seekpos = 0; seekpos < size; seekpos += os::vm_page_size()) {
853 int zero_int = 0;
854 result = (int)os::seek_to_file_offset(fd, (jlong)(seekpos));
855 if (result == -1 ) break;
856 RESTARTABLE(::write(fd, &zero_int, 1), result);
857 if (result != 1) {
858 if (errno == ENOSPC) {
859 warning("Insufficient space for shared memory file:\n %s\nTry using the -Djava.io.tmpdir= option to select an alternate temp location.\n", filename);
860 }
861 break;
862 }
863 }
864
865 if (result != -1) {
866 return fd;
867 } else {
868 ::close(fd);
869 return -1;
870 }
871 }
872
873 // open the shared memory file for the given user and vmid. returns
874 // the file descriptor for the open file or -1 if the file could not
875 // be opened.
876 //
877 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
878
879 // open the file
880 int result;
881 RESTARTABLE(::open(filename, oflags), result);
882 if (result == OS_ERR) {
883 if (errno == ENOENT) {
884 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
885 "Process not found", OS_ERR);
886 }
887 else if (errno == EACCES) {
888 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
889 "Permission denied", OS_ERR);
890 }
891 else {
892 THROW_MSG_(vmSymbols::java_io_IOException(),
893 os::strerror(errno), OS_ERR);
894 }
895 }
896 int fd = result;
897
898 // check to see if the file is secure
899 if (!is_file_secure(fd, filename)) {
900 ::close(fd);
901 return -1;
902 }
903
904 return fd;
905 }
906
907 // create a named shared memory region. returns the address of the
908 // memory region on success or NULL on failure. A return value of
909 // NULL will ultimately disable the shared memory feature.
910 //
911 // On BSD, the name space for shared memory objects
912 // is the file system name space.
913 //
914 // A monitoring application attaching to a JVM does not need to know
915 // the file system name of the shared memory object. However, it may
916 // be convenient for applications to discover the existence of newly
917 // created and terminating JVMs by watching the file system name space
918 // for files being created or removed.
919 //
920 static char* mmap_create_shared(size_t size) {
921
922 int result;
923 int fd;
924 char* mapAddress;
925
926 int vmid = os::current_process_id();
927
928 char* user_name = get_user_name(geteuid());
929
930 if (user_name == NULL)
931 return NULL;
932
933 char* dirname = get_user_tmp_dir(user_name);
934 char* filename = get_sharedmem_filename(dirname, vmid);
935
936 // get the short filename
937 char* short_filename = strrchr(filename, '/');
938 if (short_filename == NULL) {
939 short_filename = filename;
940 } else {
941 short_filename++;
942 }
943
944 // cleanup any stale shared memory files
945 cleanup_sharedmem_resources(dirname);
946
947 assert(((size > 0) && (size % os::vm_page_size() == 0)),
948 "unexpected PerfMemory region size");
949
950 fd = create_sharedmem_resources(dirname, short_filename, size);
951
952 FREE_C_HEAP_ARRAY(char, user_name);
953 FREE_C_HEAP_ARRAY(char, dirname);
954
955 if (fd == -1) {
956 FREE_C_HEAP_ARRAY(char, filename);
957 return NULL;
958 }
959
960 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
961
962 result = ::close(fd);
963 assert(result != OS_ERR, "could not close file");
964
965 if (mapAddress == MAP_FAILED) {
966 if (PrintMiscellaneous && Verbose) {
967 warning("mmap failed - %s\n", os::strerror(errno));
968 }
969 remove_file(filename);
970 FREE_C_HEAP_ARRAY(char, filename);
971 return NULL;
972 }
973
974 // save the file name for use in delete_shared_memory()
975 backing_store_file_name = filename;
976
977 // clear the shared memory region
978 (void)::memset((void*) mapAddress, 0, size);
979
980 // it does not go through os api, the operation has to record from here
981 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal);
982
983 return mapAddress;
984 }
985
986 // release a named shared memory region
987 //
988 static void unmap_shared(char* addr, size_t bytes) {
989 os::release_memory(addr, bytes);
990 }
991
992 // create the PerfData memory region in shared memory.
993 //
994 static char* create_shared_memory(size_t size) {
995
996 // create the shared memory region.
997 return mmap_create_shared(size);
998 }
999
1000 // delete the shared PerfData memory region
1001 //
1002 static void delete_shared_memory(char* addr, size_t size) {
1003
1004 // cleanup the persistent shared memory resources. since DestroyJavaVM does
1005 // not support unloading of the JVM, unmapping of the memory resource is
1006 // not performed. The memory will be reclaimed by the OS upon termination of
1007 // the process. The backing store file is deleted from the file system.
1008
1009 assert(!PerfDisableSharedMem, "shouldn't be here");
1010
1011 if (backing_store_file_name != NULL) {
1012 remove_file(backing_store_file_name);
1013 // Don't.. Free heap memory could deadlock os::abort() if it is called
1014 // from signal handler. OS will reclaim the heap memory.
1015 // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
1016 backing_store_file_name = NULL;
1017 }
1018 }
1019
1020 // return the size of the file for the given file descriptor
1021 // or 0 if it is not a valid size for a shared memory file
1022 //
1023 static size_t sharedmem_filesize(int fd, TRAPS) {
1024
1025 struct stat statbuf;
1026 int result;
1027
1028 RESTARTABLE(::fstat(fd, &statbuf), result);
1029 if (result == OS_ERR) {
1030 if (PrintMiscellaneous && Verbose) {
1031 warning("fstat failed: %s\n", os::strerror(errno));
1032 }
1033 THROW_MSG_0(vmSymbols::java_io_IOException(),
1034 "Could not determine PerfMemory size");
1035 }
1036
1037 if ((statbuf.st_size == 0) ||
1038 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
1039 THROW_MSG_0(vmSymbols::java_lang_Exception(),
1040 "Invalid PerfMemory size");
1041 }
1042
1043 return (size_t)statbuf.st_size;
1044 }
1045
1046 // attach to a named shared memory region.
1047 //
1048 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
1049
1050 char* mapAddress;
1051 int result;
1052 int fd;
1053 size_t size = 0;
1054 const char* luser = NULL;
1055
1056 int mmap_prot;
1057 int file_flags;
1058
1059 ResourceMark rm;
1060
1061 // map the high level access mode to the appropriate permission
1062 // constructs for the file and the shared memory mapping.
1063 if (mode == PerfMemory::PERF_MODE_RO) {
1064 mmap_prot = PROT_READ;
1065 file_flags = O_RDONLY | O_NOFOLLOW;
1066 }
1067 else if (mode == PerfMemory::PERF_MODE_RW) {
1068 #ifdef LATER
1069 mmap_prot = PROT_READ | PROT_WRITE;
1070 file_flags = O_RDWR | O_NOFOLLOW;
1071 #else
1072 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1073 "Unsupported access mode");
1074 #endif
1075 }
1076 else {
1077 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1078 "Illegal access mode");
1079 }
1080
1081 if (user == NULL || strlen(user) == 0) {
1082 luser = get_user_name(vmid, CHECK);
1083 }
1084 else {
1085 luser = user;
1086 }
1087
1088 if (luser == NULL) {
1089 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1090 "Could not map vmid to user Name");
1091 }
1092
1093 char* dirname = get_user_tmp_dir(luser);
1094
1095 // since we don't follow symbolic links when creating the backing
1096 // store file, we don't follow them when attaching either.
1097 //
1098 if (!is_directory_secure(dirname)) {
1099 FREE_C_HEAP_ARRAY(char, dirname);
1100 if (luser != user) {
1101 FREE_C_HEAP_ARRAY(char, luser);
1102 }
1103 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1104 "Process not found");
1105 }
1106
1107 char* filename = get_sharedmem_filename(dirname, vmid);
1108
1109 // copy heap memory to resource memory. the open_sharedmem_file
1110 // method below need to use the filename, but could throw an
1111 // exception. using a resource array prevents the leak that
1112 // would otherwise occur.
1113 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
1114 strcpy(rfilename, filename);
1115
1116 // free the c heap resources that are no longer needed
1117 if (luser != user) FREE_C_HEAP_ARRAY(char, luser);
1118 FREE_C_HEAP_ARRAY(char, dirname);
1119 FREE_C_HEAP_ARRAY(char, filename);
1120
1121 // open the shared memory file for the give vmid
1122 fd = open_sharedmem_file(rfilename, file_flags, CHECK);
1123 assert(fd != OS_ERR, "unexpected value");
1124
1125 if (*sizep == 0) {
1126 size = sharedmem_filesize(fd, CHECK);
1127 } else {
1128 size = *sizep;
1129 }
1130
1131 assert(size > 0, "unexpected size <= 0");
1132
1133 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
1134
1135 // attempt to close the file - restart if it gets interrupted,
1136 // but ignore other failures
1137 result = ::close(fd);
1138 assert(result != OS_ERR, "could not close file");
1139
1140 if (mapAddress == MAP_FAILED) {
1141 if (PrintMiscellaneous && Verbose) {
1142 warning("mmap failed: %s\n", os::strerror(errno));
1143 }
1144 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
1145 "Could not map PerfMemory");
1146 }
1147
1148 // it does not go through os api, the operation has to record from here
1149 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal);
1150
1151 *addr = mapAddress;
1152 *sizep = size;
1153
1154 log_debug(perf, memops)("mapped " SIZE_FORMAT " bytes for vmid %d at "
1155 INTPTR_FORMAT "\n", size, vmid, p2i((void*)mapAddress));
1156 }
1157
1158 // create the PerfData memory region
1159 //
1160 // This method creates the memory region used to store performance
1161 // data for the JVM. The memory may be created in standard or
1162 // shared memory.
1163 //
1164 void PerfMemory::create_memory_region(size_t size) {
1165
1166 if (PerfDisableSharedMem) {
1167 // do not share the memory for the performance data.
1168 _start = create_standard_memory(size);
1169 }
1170 else {
1171 _start = create_shared_memory(size);
1172 if (_start == NULL) {
1173
1174 // creation of the shared memory region failed, attempt
1175 // to create a contiguous, non-shared memory region instead.
1176 //
1177 if (PrintMiscellaneous && Verbose) {
1178 warning("Reverting to non-shared PerfMemory region.\n");
1179 }
1180 PerfDisableSharedMem = true;
1181 _start = create_standard_memory(size);
1182 }
1183 }
1184
1185 if (_start != NULL) _capacity = size;
1186
1187 }
1188
1189 // delete the PerfData memory region
1190 //
1191 // This method deletes the memory region used to store performance
1192 // data for the JVM. The memory region indicated by the <address, size>
1193 // tuple will be inaccessible after a call to this method.
1194 //
1195 void PerfMemory::delete_memory_region() {
1196
1197 assert((start() != NULL && capacity() > 0), "verify proper state");
1198
1199 // If user specifies PerfDataSaveFile, it will save the performance data
1200 // to the specified file name no matter whether PerfDataSaveToFile is specified
1201 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
1202 // -XX:+PerfDataSaveToFile.
1203 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
1204 save_memory_to_file(start(), capacity());
1205 }
1206
1207 if (PerfDisableSharedMem) {
1208 delete_standard_memory(start(), capacity());
1209 }
1210 else {
1211 delete_shared_memory(start(), capacity());
1212 }
1213 }
1214
1215 // attach to the PerfData memory region for another JVM
1216 //
1217 // This method returns an <address, size> tuple that points to
1218 // a memory buffer that is kept reasonably synchronized with
1219 // the PerfData memory region for the indicated JVM. This
1220 // buffer may be kept in synchronization via shared memory
1221 // or some other mechanism that keeps the buffer updated.
1222 //
1223 // If the JVM chooses not to support the attachability feature,
1224 // this method should throw an UnsupportedOperation exception.
1225 //
1226 // This implementation utilizes named shared memory to map
1227 // the indicated process's PerfData memory region into this JVMs
1228 // address space.
1229 //
1230 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
1231
1232 if (vmid == 0 || vmid == os::current_process_id()) {
1233 *addrp = start();
1234 *sizep = capacity();
1235 return;
1236 }
1237
1238 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
1239 }
1240
1241 // detach from the PerfData memory region of another JVM
1242 //
1243 // This method detaches the PerfData memory region of another
1244 // JVM, specified as an <address, size> tuple of a buffer
1245 // in this process's address space. This method may perform
1246 // arbitrary actions to accomplish the detachment. The memory
1247 // region specified by <address, size> will be inaccessible after
1248 // a call to this method.
1249 //
1250 // If the JVM chooses not to support the attachability feature,
1251 // this method should throw an UnsupportedOperation exception.
1252 //
1253 // This implementation utilizes named shared memory to detach
1254 // the indicated process's PerfData memory region from this
1255 // process's address space.
1256 //
1257 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1258
1259 assert(addr != 0, "address sanity check");
1260 assert(bytes > 0, "capacity sanity check");
1261
1262 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1263 // prevent accidental detachment of this process's PerfMemory region
1264 return;
1265 }
1266
1267 unmap_shared(addr, bytes);
1268 }