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_solaris.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 # include <procfs.h>
46
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, strerror(errno));
106 }
107 } else {
108
109 int fd = result;
110
111 for (size_t remaining = size; remaining > 0;) {
112
113 RESTARTABLE(::write(fd, addr, remaining), result);
114 if (result == OS_ERR) {
115 if (PrintMiscellaneous && Verbose) {
116 warning("Could not write Perfdata save file: %s: %s\n",
117 destfile, strerror(errno));
118 }
119 break;
120 }
121 remaining -= (size_t)result;
122 addr += result;
123 }
124
125 result = ::close(fd);
126 if (PrintMiscellaneous && Verbose) {
127 if (result == OS_ERR) {
128 warning("Could not close %s: %s\n", destfile, strerror(errno));
129 }
130 }
131 }
132 FREE_C_HEAP_ARRAY(char, destfile, mtInternal);
133 }
134
135
136 // Shared Memory Implementation Details
137
138 // Note: the solaris and linux shared memory implementation uses the mmap
139 // interface with a backing store file to implement named shared memory.
140 // Using the file system as the name space for shared memory allows a
141 // common name space to be supported across a variety of platforms. It
142 // also provides a name space that Java applications can deal with through
143 // simple file apis.
144 //
145 // The solaris and linux implementations store the backing store file in
146 // a user specific temporary directory located in the /tmp file system,
147 // which is always a local file system and is sometimes a RAM based file
148 // system.
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, 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, dirp->dd_fd)) {
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 = dirp->dd_fd;
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, 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 #ifdef _GNU_SOURCE
457 struct passwd* p = NULL;
458 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);
459 #else // _GNU_SOURCE
460 struct passwd* p = getpwuid_r(uid, &pwent, pwbuf, (int)bufsize);
461 #endif // _GNU_SOURCE
462
463 if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {
464 if (PrintMiscellaneous && Verbose) {
465 if (p == NULL) {
466 warning("Could not retrieve passwd entry: %s\n",
467 strerror(errno));
468 }
469 else {
470 warning("Could not determine user name: %s\n",
471 p->pw_name == NULL ? "pw_name = NULL" :
472 "pw_name zero length");
473 }
474 }
475 FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal);
476 return NULL;
477 }
478
479 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal);
480 strcpy(user_name, p->pw_name);
481
482 FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal);
483 return user_name;
484 }
485
486 // return the name of the user that owns the process identified by vmid.
487 //
488 // This method uses a slow directory search algorithm to find the backing
489 // store file for the specified vmid and returns the user name, as determined
490 // by the user name suffix of the hsperfdata_<username> directory name.
491 //
492 // the caller is expected to free the allocated memory.
493 //
494 static char* get_user_name_slow(int vmid, TRAPS) {
495
496 // short circuit the directory search if the process doesn't even exist.
497 if (kill(vmid, 0) == OS_ERR) {
498 if (errno == ESRCH) {
499 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
500 "Process not found");
501 }
502 else /* EPERM */ {
503 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));
504 }
505 }
506
507 // directory search
508 char* oldest_user = NULL;
509 time_t oldest_ctime = 0;
510
511 const char* tmpdirname = os::get_temp_directory();
512
513 // open the temp directory
514 DIR* tmpdirp = os::opendir(tmpdirname);
515
516 if (tmpdirp == NULL) {
517 // Cannot open the directory to get the user name, return.
518 return NULL;
519 }
520
521 // for each entry in the directory that matches the pattern hsperfdata_*,
522 // open the directory and check if the file for the given vmid exists.
523 // The file with the expected name and the latest creation date is used
524 // to determine the user name for the process id.
525 //
526 struct dirent* dentry;
527 errno = 0;
528 while ((dentry = os::readdir(tmpdirp)) != NULL) {
529
530 // check if the directory entry is a hsperfdata file
531 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
532 continue;
533 }
534
535 char* usrdir_name = NEW_C_HEAP_ARRAY(char,
536 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
537 strcpy(usrdir_name, tmpdirname);
538 strcat(usrdir_name, "/");
539 strcat(usrdir_name, dentry->d_name);
540
541 // open the user directory
542 DIR* subdirp = open_directory_secure(usrdir_name);
543
544 if (subdirp == NULL) {
545 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
546 continue;
547 }
548
549 // Since we don't create the backing store files in directories
550 // pointed to by symbolic links, we also don't follow them when
551 // looking for the files. We check for a symbolic link after the
552 // call to opendir in order to eliminate a small window where the
553 // symlink can be exploited.
554 //
555 if (!is_directory_secure(usrdir_name)) {
556 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
557 os::closedir(subdirp);
558 continue;
559 }
560
561 struct dirent* udentry;
562 errno = 0;
563 while ((udentry = os::readdir(subdirp)) != 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, mtInternal);
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, mtInternal);
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, mtInternal);
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, mtInternal);
604 }
605 }
606 os::closedir(subdirp);
607 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
608 }
609 os::closedir(tmpdirp);
610
611 return(oldest_user);
612 }
613
614 // return the name of the user that owns the JVM indicated by the given vmid.
615 //
616 static char* get_user_name(int vmid, TRAPS) {
617
618 char psinfo_name[PATH_MAX];
619 int result;
620
621 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid);
622
623 RESTARTABLE(::open(psinfo_name, O_RDONLY), result);
624
625 if (result != OS_ERR) {
626 int fd = result;
627
628 psinfo_t psinfo;
629 char* addr = (char*)&psinfo;
630
631 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) {
632
633 RESTARTABLE(::read(fd, addr, remaining), result);
634 if (result == OS_ERR) {
635 ::close(fd);
636 THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error");
637 } else {
638 remaining-=result;
639 addr+=result;
640 }
641 }
642
643 ::close(fd);
644
645 // get the user name for the effective user id of the process
646 char* user_name = get_user_name(psinfo.pr_euid);
647
648 return user_name;
649 }
650
651 if (result == OS_ERR && errno == EACCES) {
652
653 // In this case, the psinfo file for the process id existed,
654 // but we didn't have permission to access it.
655 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
656 strerror(errno));
657 }
658
659 // at this point, we don't know if the process id itself doesn't
660 // exist or if the psinfo file doesn't exit. If the psinfo file
661 // doesn't exist, then we are running on Solaris 2.5.1 or earlier.
662 // since the structured procfs and old procfs interfaces can't be
663 // mixed, we attempt to find the file through a directory search.
664
665 return get_user_name_slow(vmid, CHECK_NULL);
666 }
667
668 // return the file name of the backing store file for the named
669 // shared memory region for the given user name and vmid.
670 //
671 // the caller is expected to free the allocated memory.
672 //
673 static char* get_sharedmem_filename(const char* dirname, int vmid) {
674
675 // add 2 for the file separator and a NULL terminator.
676 size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
677
678 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
679 snprintf(name, nbytes, "%s/%d", dirname, vmid);
680
681 return name;
682 }
683
684
685 // remove file
686 //
687 // this method removes the file specified by the given path
688 //
689 static void remove_file(const char* path) {
690
691 int result;
692
693 // if the file is a directory, the following unlink will fail. since
694 // we don't expect to find directories in the user temp directory, we
695 // won't try to handle this situation. even if accidentially or
696 // maliciously planted, the directory's presence won't hurt anything.
697 //
698 RESTARTABLE(::unlink(path), result);
699 if (PrintMiscellaneous && Verbose && result == OS_ERR) {
700 if (errno != ENOENT) {
701 warning("Could not unlink shared memory backing"
702 " store file %s : %s\n", path, strerror(errno));
703 }
704 }
705 }
706
707
708 // cleanup stale shared memory resources
709 //
710 // This method attempts to remove all stale shared memory files in
711 // the named user temporary directory. It scans the named directory
712 // for files matching the pattern ^$[0-9]*$. For each file found, the
713 // process id is extracted from the file name and a test is run to
714 // determine if the process is alive. If the process is not alive,
715 // any stale file resources are removed.
716 //
717 static void cleanup_sharedmem_resources(const char* dirname) {
718
719 int saved_cwd_fd;
720 // open the directory
721 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
722 if (dirp == NULL) {
723 // directory doesn't exist or is insecure, so there is nothing to cleanup
724 return;
725 }
726
727 // for each entry in the directory that matches the expected file
728 // name pattern, determine if the file resources are stale and if
729 // so, remove the file resources. Note, instrumented HotSpot processes
730 // for this user may start and/or terminate during this search and
731 // remove or create new files in this directory. The behavior of this
732 // loop under these conditions is dependent upon the implementation of
733 // opendir/readdir.
734 //
735 struct dirent* entry;
736 errno = 0;
737 while ((entry = os::readdir(dirp)) != NULL) {
738
739 pid_t pid = filename_to_pid(entry->d_name);
740
741 if (pid == 0) {
742
743 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
744
745 // attempt to remove all unexpected files, except "." and ".."
746 unlink(entry->d_name);
747 }
748
749 errno = 0;
750 continue;
751 }
752
753 // we now have a file name that converts to a valid integer
754 // that could represent a process id . if this process id
755 // matches the current process id or the process is not running,
756 // then remove the stale file resources.
757 //
758 // process liveness is detected by sending signal number 0 to
759 // the process id (see kill(2)). if kill determines that the
760 // process does not exist, then the file resources are removed.
761 // if kill determines that that we don't have permission to
762 // signal the process, then the file resources are assumed to
763 // be stale and are removed because the resources for such a
764 // process should be in a different user specific directory.
765 //
766 if ((pid == os::current_process_id()) ||
767 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
768
769 unlink(entry->d_name);
770 }
771 errno = 0;
772 }
773
774 // close the directory and reset the current working directory
775 close_directory_secure_cwd(dirp, saved_cwd_fd);
776 }
777
778 // make the user specific temporary directory. Returns true if
779 // the directory exists and is secure upon return. Returns false
780 // if the directory exists but is either a symlink, is otherwise
781 // insecure, or if an error occurred.
782 //
783 static bool make_user_tmp_dir(const char* dirname) {
784
785 // create the directory with 0755 permissions. note that the directory
786 // will be owned by euid::egid, which may not be the same as uid::gid.
787 //
788 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
789 if (errno == EEXIST) {
790 // The directory already exists and was probably created by another
791 // JVM instance. However, this could also be the result of a
792 // deliberate symlink. Verify that the existing directory is safe.
793 //
794 if (!is_directory_secure(dirname)) {
795 // directory is not secure
796 if (PrintMiscellaneous && Verbose) {
797 warning("%s directory is insecure\n", dirname);
798 }
799 return false;
800 }
801 }
802 else {
803 // we encountered some other failure while attempting
804 // to create the directory
805 //
806 if (PrintMiscellaneous && Verbose) {
807 warning("could not create directory %s: %s\n",
808 dirname, strerror(errno));
809 }
810 return false;
811 }
812 }
813 return true;
814 }
815
816 // create the shared memory file resources
817 //
818 // This method creates the shared memory file with the given size
819 // This method also creates the user specific temporary directory, if
820 // it does not yet exist.
821 //
822 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
823
824 // make the user temporary directory
825 if (!make_user_tmp_dir(dirname)) {
826 // could not make/find the directory or the found directory
827 // was not secure
828 return -1;
829 }
830
831 int saved_cwd_fd;
832 // open the directory and set the current working directory to it
833 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
834 if (dirp == NULL) {
835 // Directory doesn't exist or is insecure, so cannot create shared
836 // memory file.
837 return -1;
838 }
839
840 // Open the filename in the current directory.
841 // Cannot use O_TRUNC here; truncation of an existing file has to happen
842 // after the is_file_secure() check below.
843 int result;
844 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result);
845 if (result == OS_ERR) {
846 if (PrintMiscellaneous && Verbose) {
847 if (errno == ELOOP) {
848 warning("file %s is a symlink and is not secure\n", filename);
849 } else {
850 warning("could not create file %s: %s\n", filename, strerror(errno));
851 }
852 }
853 // close the directory and reset the current working directory
854 close_directory_secure_cwd(dirp, saved_cwd_fd);
855
856 return -1;
857 }
858 // close the directory and reset the current working directory
859 close_directory_secure_cwd(dirp, saved_cwd_fd);
860
861 // save the file descriptor
862 int fd = result;
863
864 // check to see if the file is secure
865 if (!is_file_secure(fd, filename)) {
866 ::close(fd);
867 return -1;
868 }
869
870 // truncate the file to get rid of any existing data
871 RESTARTABLE(::ftruncate(fd, (off_t)0), result);
872 if (result == OS_ERR) {
873 if (PrintMiscellaneous && Verbose) {
874 warning("could not truncate shared memory file: %s\n", strerror(errno));
875 }
876 ::close(fd);
877 return -1;
878 }
879 // set the file size
880 RESTARTABLE(::ftruncate(fd, (off_t)size), result);
881 if (result == OS_ERR) {
882 if (PrintMiscellaneous && Verbose) {
883 warning("could not set shared memory file size: %s\n", strerror(errno));
884 }
885 ::close(fd);
886 return -1;
887 }
888
889 return fd;
890 }
891
892 // open the shared memory file for the given user and vmid. returns
893 // the file descriptor for the open file or -1 if the file could not
894 // be opened.
895 //
896 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
897
898 // open the file
899 int result;
900 RESTARTABLE(::open(filename, oflags), result);
901 if (result == OS_ERR) {
902 if (errno == ENOENT) {
903 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
904 "Process not found", OS_ERR);
905 }
906 else if (errno == EACCES) {
907 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
908 "Permission denied", OS_ERR);
909 }
910 else {
911 THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR);
912 }
913 }
914 int fd = result;
915
916 // check to see if the file is secure
917 if (!is_file_secure(fd, filename)) {
918 ::close(fd);
919 return -1;
920 }
921
922 return fd;
923 }
924
925 // create a named shared memory region. returns the address of the
926 // memory region on success or NULL on failure. A return value of
927 // NULL will ultimately disable the shared memory feature.
928 //
929 // On Solaris and Linux, the name space for shared memory objects
930 // is the file system name space.
931 //
932 // A monitoring application attaching to a JVM does not need to know
933 // the file system name of the shared memory object. However, it may
934 // be convenient for applications to discover the existence of newly
935 // created and terminating JVMs by watching the file system name space
936 // for files being created or removed.
937 //
938 static char* mmap_create_shared(size_t size) {
939
940 int result;
941 int fd;
942 char* mapAddress;
943
944 int vmid = os::current_process_id();
945
946 char* user_name = get_user_name(geteuid());
947
948 if (user_name == NULL)
949 return NULL;
950
951 char* dirname = get_user_tmp_dir(user_name);
952 char* filename = get_sharedmem_filename(dirname, vmid);
953
954 // get the short filename
955 char* short_filename = strrchr(filename, '/');
956 if (short_filename == NULL) {
957 short_filename = filename;
958 } else {
959 short_filename++;
960 }
961
962 // cleanup any stale shared memory files
963 cleanup_sharedmem_resources(dirname);
964
965 assert(((size > 0) && (size % os::vm_page_size() == 0)),
966 "unexpected PerfMemory region size");
967
968 fd = create_sharedmem_resources(dirname, short_filename, size);
969
970 FREE_C_HEAP_ARRAY(char, user_name, mtInternal);
971 FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
972
973 if (fd == -1) {
974 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
975 return NULL;
976 }
977
978 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
979
980 result = ::close(fd);
981 assert(result != OS_ERR, "could not close file");
982
983 if (mapAddress == MAP_FAILED) {
984 if (PrintMiscellaneous && Verbose) {
985 warning("mmap failed - %s\n", strerror(errno));
986 }
987 remove_file(filename);
988 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
989 return NULL;
990 }
991
992 // save the file name for use in delete_shared_memory()
993 backing_store_file_name = filename;
994
995 // clear the shared memory region
996 (void)::memset((void*) mapAddress, 0, size);
997
998 // it does not go through os api, the operation has to record from here
999 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress,
1000 size, CURRENT_PC, mtInternal);
1001
1002 return mapAddress;
1003 }
1004
1005 // release a named shared memory region
1006 //
1007 static void unmap_shared(char* addr, size_t bytes) {
1008 os::release_memory(addr, bytes);
1009 }
1010
1011 // create the PerfData memory region in shared memory.
1012 //
1013 static char* create_shared_memory(size_t size) {
1014
1015 // create the shared memory region.
1016 return mmap_create_shared(size);
1017 }
1018
1019 // delete the shared PerfData memory region
1020 //
1021 static void delete_shared_memory(char* addr, size_t size) {
1022
1023 // cleanup the persistent shared memory resources. since DestroyJavaVM does
1024 // not support unloading of the JVM, unmapping of the memory resource is
1025 // not performed. The memory will be reclaimed by the OS upon termination of
1026 // the process. The backing store file is deleted from the file system.
1027
1028 assert(!PerfDisableSharedMem, "shouldn't be here");
1029
1030 if (backing_store_file_name != NULL) {
1031 remove_file(backing_store_file_name);
1032 // Don't.. Free heap memory could deadlock os::abort() if it is called
1033 // from signal handler. OS will reclaim the heap memory.
1034 // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
1035 backing_store_file_name = NULL;
1036 }
1037 }
1038
1039 // return the size of the file for the given file descriptor
1040 // or 0 if it is not a valid size for a shared memory file
1041 //
1042 static size_t sharedmem_filesize(int fd, TRAPS) {
1043
1044 struct stat statbuf;
1045 int result;
1046
1047 RESTARTABLE(::fstat(fd, &statbuf), result);
1048 if (result == OS_ERR) {
1049 if (PrintMiscellaneous && Verbose) {
1050 warning("fstat failed: %s\n", strerror(errno));
1051 }
1052 THROW_MSG_0(vmSymbols::java_io_IOException(),
1053 "Could not determine PerfMemory size");
1054 }
1055
1056 if ((statbuf.st_size == 0) ||
1057 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
1058 THROW_MSG_0(vmSymbols::java_lang_Exception(),
1059 "Invalid PerfMemory size");
1060 }
1061
1062 return (size_t)statbuf.st_size;
1063 }
1064
1065 // attach to a named shared memory region.
1066 //
1067 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
1068
1069 char* mapAddress;
1070 int result;
1071 int fd;
1072 size_t size = 0;
1073 const char* luser = NULL;
1074
1075 int mmap_prot;
1076 int file_flags;
1077
1078 ResourceMark rm;
1079
1080 // map the high level access mode to the appropriate permission
1081 // constructs for the file and the shared memory mapping.
1082 if (mode == PerfMemory::PERF_MODE_RO) {
1083 mmap_prot = PROT_READ;
1084 file_flags = O_RDONLY | O_NOFOLLOW;
1085 }
1086 else if (mode == PerfMemory::PERF_MODE_RW) {
1087 #ifdef LATER
1088 mmap_prot = PROT_READ | PROT_WRITE;
1089 file_flags = O_RDWR | O_NOFOLLOW;
1090 #else
1091 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1092 "Unsupported access mode");
1093 #endif
1094 }
1095 else {
1096 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1097 "Illegal access mode");
1098 }
1099
1100 if (user == NULL || strlen(user) == 0) {
1101 luser = get_user_name(vmid, CHECK);
1102 }
1103 else {
1104 luser = user;
1105 }
1106
1107 if (luser == NULL) {
1108 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1109 "Could not map vmid to user Name");
1110 }
1111
1112 char* dirname = get_user_tmp_dir(luser);
1113
1114 // since we don't follow symbolic links when creating the backing
1115 // store file, we don't follow them when attaching either.
1116 //
1117 if (!is_directory_secure(dirname)) {
1118 FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
1119 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1120 "Process not found");
1121 }
1122
1123 char* filename = get_sharedmem_filename(dirname, vmid);
1124
1125 // copy heap memory to resource memory. the open_sharedmem_file
1126 // method below need to use the filename, but could throw an
1127 // exception. using a resource array prevents the leak that
1128 // would otherwise occur.
1129 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
1130 strcpy(rfilename, filename);
1131
1132 // free the c heap resources that are no longer needed
1133 if (luser != user) FREE_C_HEAP_ARRAY(char, luser, mtInternal);
1134 FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
1135 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
1136
1137 // open the shared memory file for the give vmid
1138 fd = open_sharedmem_file(rfilename, file_flags, THREAD);
1139
1140 if (fd == OS_ERR) {
1141 return;
1142 }
1143
1144 if (HAS_PENDING_EXCEPTION) {
1145 ::close(fd);
1146 return;
1147 }
1148
1149 if (*sizep == 0) {
1150 size = sharedmem_filesize(fd, CHECK);
1151 } else {
1152 size = *sizep;
1153 }
1154
1155 assert(size > 0, "unexpected size <= 0");
1156
1157 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
1158
1159 result = ::close(fd);
1160 assert(result != OS_ERR, "could not close file");
1161
1162 if (mapAddress == MAP_FAILED) {
1163 if (PrintMiscellaneous && Verbose) {
1164 warning("mmap failed: %s\n", strerror(errno));
1165 }
1166 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
1167 "Could not map PerfMemory");
1168 }
1169
1170 // it does not go through os api, the operation has to record from here
1171 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress,
1172 size, CURRENT_PC, mtInternal);
1173
1174 *addr = mapAddress;
1175 *sizep = size;
1176
1177 if (PerfTraceMemOps) {
1178 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
1179 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress);
1180 }
1181 }
1182
1183
1184
1185
1186 // create the PerfData memory region
1187 //
1188 // This method creates the memory region used to store performance
1189 // data for the JVM. The memory may be created in standard or
1190 // shared memory.
1191 //
1192 void PerfMemory::create_memory_region(size_t size) {
1193
1194 if (PerfDisableSharedMem) {
1195 // do not share the memory for the performance data.
1196 _start = create_standard_memory(size);
1197 }
1198 else {
1199 _start = create_shared_memory(size);
1200 if (_start == NULL) {
1201
1202 // creation of the shared memory region failed, attempt
1203 // to create a contiguous, non-shared memory region instead.
1204 //
1205 if (PrintMiscellaneous && Verbose) {
1206 warning("Reverting to non-shared PerfMemory region.\n");
1207 }
1208 PerfDisableSharedMem = true;
1209 _start = create_standard_memory(size);
1210 }
1211 }
1212
1213 if (_start != NULL) _capacity = size;
1214
1215 }
1216
1217 // delete the PerfData memory region
1218 //
1219 // This method deletes the memory region used to store performance
1220 // data for the JVM. The memory region indicated by the <address, size>
1221 // tuple will be inaccessible after a call to this method.
1222 //
1223 void PerfMemory::delete_memory_region() {
1224
1225 assert((start() != NULL && capacity() > 0), "verify proper state");
1226
1227 // If user specifies PerfDataSaveFile, it will save the performance data
1228 // to the specified file name no matter whether PerfDataSaveToFile is specified
1229 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
1230 // -XX:+PerfDataSaveToFile.
1231 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
1232 save_memory_to_file(start(), capacity());
1233 }
1234
1235 if (PerfDisableSharedMem) {
1236 delete_standard_memory(start(), capacity());
1237 }
1238 else {
1239 delete_shared_memory(start(), capacity());
1240 }
1241 }
1242
1243 // attach to the PerfData memory region for another JVM
1244 //
1245 // This method returns an <address, size> tuple that points to
1246 // a memory buffer that is kept reasonably synchronized with
1247 // the PerfData memory region for the indicated JVM. This
1248 // buffer may be kept in synchronization via shared memory
1249 // or some other mechanism that keeps the buffer updated.
1250 //
1251 // If the JVM chooses not to support the attachability feature,
1252 // this method should throw an UnsupportedOperation exception.
1253 //
1254 // This implementation utilizes named shared memory to map
1255 // the indicated process's PerfData memory region into this JVMs
1256 // address space.
1257 //
1258 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
1259
1260 if (vmid == 0 || vmid == os::current_process_id()) {
1261 *addrp = start();
1262 *sizep = capacity();
1263 return;
1264 }
1265
1266 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
1267 }
1268
1269 // detach from the PerfData memory region of another JVM
1270 //
1271 // This method detaches the PerfData memory region of another
1272 // JVM, specified as an <address, size> tuple of a buffer
1273 // in this process's address space. This method may perform
1274 // arbitrary actions to accomplish the detachment. The memory
1275 // region specified by <address, size> will be inaccessible after
1276 // a call to this method.
1277 //
1278 // If the JVM chooses not to support the attachability feature,
1279 // this method should throw an UnsupportedOperation exception.
1280 //
1281 // This implementation utilizes named shared memory to detach
1282 // the indicated process's PerfData memory region from this
1283 // process's address space.
1284 //
1285 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1286
1287 assert(addr != 0, "address sanity check");
1288 assert(bytes > 0, "capacity sanity check");
1289
1290 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1291 // prevent accidental detachment of this process's PerfMemory region
1292 return;
1293 }
1294
1295 unmap_shared(addr, bytes);
1296 }
1297
1298 char* PerfMemory::backing_store_filename() {
1299 return backing_store_file_name;
1300 }