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 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
528 errno = 0;
529 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
530
531 // check if the directory entry is a hsperfdata file
532 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
533 continue;
534 }
535
536 char* usrdir_name = NEW_C_HEAP_ARRAY(char,
537 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
538 strcpy(usrdir_name, tmpdirname);
539 strcat(usrdir_name, "/");
540 strcat(usrdir_name, dentry->d_name);
541
542 // open the user directory
543 DIR* subdirp = open_directory_secure(usrdir_name);
544
545 if (subdirp == NULL) {
546 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
547 continue;
548 }
549
550 // Since we don't create the backing store files in directories
551 // pointed to by symbolic links, we also don't follow them when
552 // looking for the files. We check for a symbolic link after the
553 // call to opendir in order to eliminate a small window where the
554 // symlink can be exploited.
555 //
556 if (!is_directory_secure(usrdir_name)) {
557 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
558 os::closedir(subdirp);
559 continue;
560 }
561
562 struct dirent* udentry;
563 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
564 errno = 0;
565 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
566
567 if (filename_to_pid(udentry->d_name) == vmid) {
568 struct stat statbuf;
569 int result;
570
571 char* filename = NEW_C_HEAP_ARRAY(char,
572 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
573
574 strcpy(filename, usrdir_name);
575 strcat(filename, "/");
576 strcat(filename, udentry->d_name);
577
578 // don't follow symbolic links for the file
579 RESTARTABLE(::lstat(filename, &statbuf), result);
580 if (result == OS_ERR) {
581 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
582 continue;
583 }
584
585 // skip over files that are not regular files.
586 if (!S_ISREG(statbuf.st_mode)) {
587 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
588 continue;
589 }
590
591 // compare and save filename with latest creation time
592 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
593
594 if (statbuf.st_ctime > oldest_ctime) {
595 char* user = strchr(dentry->d_name, '_') + 1;
596
597 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user, mtInternal);
598 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal);
599
600 strcpy(oldest_user, user);
601 oldest_ctime = statbuf.st_ctime;
602 }
603 }
604
605 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
606 }
607 }
608 os::closedir(subdirp);
609 FREE_C_HEAP_ARRAY(char, udbuf, mtInternal);
610 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
611 }
612 os::closedir(tmpdirp);
613 FREE_C_HEAP_ARRAY(char, tdbuf, mtInternal);
614
615 return(oldest_user);
616 }
617
618 // return the name of the user that owns the JVM indicated by the given vmid.
619 //
620 static char* get_user_name(int vmid, TRAPS) {
621
622 char psinfo_name[PATH_MAX];
623 int result;
624
625 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid);
626
627 RESTARTABLE(::open(psinfo_name, O_RDONLY), result);
628
629 if (result != OS_ERR) {
630 int fd = result;
631
632 psinfo_t psinfo;
633 char* addr = (char*)&psinfo;
634
635 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) {
636
637 RESTARTABLE(::read(fd, addr, remaining), result);
638 if (result == OS_ERR) {
639 ::close(fd);
640 THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error");
641 } else {
642 remaining-=result;
643 addr+=result;
644 }
645 }
646
647 ::close(fd);
648
649 // get the user name for the effective user id of the process
650 char* user_name = get_user_name(psinfo.pr_euid);
651
652 return user_name;
653 }
654
655 if (result == OS_ERR && errno == EACCES) {
656
657 // In this case, the psinfo file for the process id existed,
658 // but we didn't have permission to access it.
659 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
660 strerror(errno));
661 }
662
663 // at this point, we don't know if the process id itself doesn't
664 // exist or if the psinfo file doesn't exit. If the psinfo file
665 // doesn't exist, then we are running on Solaris 2.5.1 or earlier.
666 // since the structured procfs and old procfs interfaces can't be
667 // mixed, we attempt to find the file through a directory search.
668
669 return get_user_name_slow(vmid, CHECK_NULL);
670 }
671
672 // return the file name of the backing store file for the named
673 // shared memory region for the given user name and vmid.
674 //
675 // the caller is expected to free the allocated memory.
676 //
677 static char* get_sharedmem_filename(const char* dirname, int vmid) {
678
679 // add 2 for the file separator and a NULL terminator.
680 size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
681
682 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
683 snprintf(name, nbytes, "%s/%d", dirname, vmid);
684
685 return name;
686 }
687
688
689 // remove file
690 //
691 // this method removes the file specified by the given path
692 //
693 static void remove_file(const char* path) {
694
695 int result;
696
697 // if the file is a directory, the following unlink will fail. since
698 // we don't expect to find directories in the user temp directory, we
699 // won't try to handle this situation. even if accidentially or
700 // maliciously planted, the directory's presence won't hurt anything.
701 //
702 RESTARTABLE(::unlink(path), result);
703 if (PrintMiscellaneous && Verbose && result == OS_ERR) {
704 if (errno != ENOENT) {
705 warning("Could not unlink shared memory backing"
706 " store file %s : %s\n", path, strerror(errno));
707 }
708 }
709 }
710
711
712 // cleanup stale shared memory resources
713 //
714 // This method attempts to remove all stale shared memory files in
715 // the named user temporary directory. It scans the named directory
716 // for files matching the pattern ^$[0-9]*$. For each file found, the
717 // process id is extracted from the file name and a test is run to
718 // determine if the process is alive. If the process is not alive,
719 // any stale file resources are removed.
720 //
721 static void cleanup_sharedmem_resources(const char* dirname) {
722
723 int saved_cwd_fd;
724 // open the directory
725 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
726 if (dirp == NULL) {
727 // directory doesn't exist or is insecure, so there is nothing to cleanup
728 return;
729 }
730
731 // for each entry in the directory that matches the expected file
732 // name pattern, determine if the file resources are stale and if
733 // so, remove the file resources. Note, instrumented HotSpot processes
734 // for this user may start and/or terminate during this search and
735 // remove or create new files in this directory. The behavior of this
736 // loop under these conditions is dependent upon the implementation of
737 // opendir/readdir.
738 //
739 struct dirent* entry;
740 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
741
742 errno = 0;
743 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
744
745 pid_t pid = filename_to_pid(entry->d_name);
746
747 if (pid == 0) {
748
749 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
750
751 // attempt to remove all unexpected files, except "." and ".."
752 unlink(entry->d_name);
753 }
754
755 errno = 0;
756 continue;
757 }
758
759 // we now have a file name that converts to a valid integer
760 // that could represent a process id . if this process id
761 // matches the current process id or the process is not running,
762 // then remove the stale file resources.
763 //
764 // process liveness is detected by sending signal number 0 to
765 // the process id (see kill(2)). if kill determines that the
766 // process does not exist, then the file resources are removed.
767 // if kill determines that that we don't have permission to
768 // signal the process, then the file resources are assumed to
769 // be stale and are removed because the resources for such a
770 // process should be in a different user specific directory.
771 //
772 if ((pid == os::current_process_id()) ||
773 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
774
775 unlink(entry->d_name);
776 }
777 errno = 0;
778 }
779
780 // close the directory and reset the current working directory
781 close_directory_secure_cwd(dirp, saved_cwd_fd);
782
783 FREE_C_HEAP_ARRAY(char, dbuf, mtInternal);
784 }
785
786 // make the user specific temporary directory. Returns true if
787 // the directory exists and is secure upon return. Returns false
788 // if the directory exists but is either a symlink, is otherwise
789 // insecure, or if an error occurred.
790 //
791 static bool make_user_tmp_dir(const char* dirname) {
792
793 // create the directory with 0755 permissions. note that the directory
794 // will be owned by euid::egid, which may not be the same as uid::gid.
795 //
796 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
797 if (errno == EEXIST) {
798 // The directory already exists and was probably created by another
799 // JVM instance. However, this could also be the result of a
800 // deliberate symlink. Verify that the existing directory is safe.
801 //
802 if (!is_directory_secure(dirname)) {
803 // directory is not secure
804 if (PrintMiscellaneous && Verbose) {
805 warning("%s directory is insecure\n", dirname);
806 }
807 return false;
808 }
809 }
810 else {
811 // we encountered some other failure while attempting
812 // to create the directory
813 //
814 if (PrintMiscellaneous && Verbose) {
815 warning("could not create directory %s: %s\n",
816 dirname, strerror(errno));
817 }
818 return false;
819 }
820 }
821 return true;
822 }
823
824 // create the shared memory file resources
825 //
826 // This method creates the shared memory file with the given size
827 // This method also creates the user specific temporary directory, if
828 // it does not yet exist.
829 //
830 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
831
832 // make the user temporary directory
833 if (!make_user_tmp_dir(dirname)) {
834 // could not make/find the directory or the found directory
835 // was not secure
836 return -1;
837 }
838
839 int saved_cwd_fd;
840 // open the directory and set the current working directory to it
841 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
842 if (dirp == NULL) {
843 // Directory doesn't exist or is insecure, so cannot create shared
844 // memory file.
845 return -1;
846 }
847
848 // Open the filename in the current directory.
849 // Cannot use O_TRUNC here; truncation of an existing file has to happen
850 // after the is_file_secure() check below.
851 int result;
852 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result);
853 if (result == OS_ERR) {
854 if (PrintMiscellaneous && Verbose) {
855 if (errno == ELOOP) {
856 warning("file %s is a symlink and is not secure\n", filename);
857 } else {
858 warning("could not create file %s: %s\n", filename, strerror(errno));
859 }
860 }
861 // close the directory and reset the current working directory
862 close_directory_secure_cwd(dirp, saved_cwd_fd);
863
864 return -1;
865 }
866 // close the directory and reset the current working directory
867 close_directory_secure_cwd(dirp, saved_cwd_fd);
868
869 // save the file descriptor
870 int fd = result;
871
872 // check to see if the file is secure
873 if (!is_file_secure(fd, filename)) {
874 ::close(fd);
875 return -1;
876 }
877
878 // truncate the file to get rid of any existing data
879 RESTARTABLE(::ftruncate(fd, (off_t)0), result);
880 if (result == OS_ERR) {
881 if (PrintMiscellaneous && Verbose) {
882 warning("could not truncate shared memory file: %s\n", strerror(errno));
883 }
884 ::close(fd);
885 return -1;
886 }
887 // set the file size
888 RESTARTABLE(::ftruncate(fd, (off_t)size), result);
889 if (result == OS_ERR) {
890 if (PrintMiscellaneous && Verbose) {
891 warning("could not set shared memory file size: %s\n", strerror(errno));
892 }
893 ::close(fd);
894 return -1;
895 }
896
897 return fd;
898 }
899
900 // open the shared memory file for the given user and vmid. returns
901 // the file descriptor for the open file or -1 if the file could not
902 // be opened.
903 //
904 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
905
906 // open the file
907 int result;
908 RESTARTABLE(::open(filename, oflags), result);
909 if (result == OS_ERR) {
910 if (errno == ENOENT) {
911 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
912 "Process not found", OS_ERR);
913 }
914 else if (errno == EACCES) {
915 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
916 "Permission denied", OS_ERR);
917 }
918 else {
919 THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR);
920 }
921 }
922 int fd = result;
923
924 // check to see if the file is secure
925 if (!is_file_secure(fd, filename)) {
926 ::close(fd);
927 return -1;
928 }
929
930 return fd;
931 }
932
933 // create a named shared memory region. returns the address of the
934 // memory region on success or NULL on failure. A return value of
935 // NULL will ultimately disable the shared memory feature.
936 //
937 // On Solaris and Linux, the name space for shared memory objects
938 // is the file system name space.
939 //
940 // A monitoring application attaching to a JVM does not need to know
941 // the file system name of the shared memory object. However, it may
942 // be convenient for applications to discover the existence of newly
943 // created and terminating JVMs by watching the file system name space
944 // for files being created or removed.
945 //
946 static char* mmap_create_shared(size_t size) {
947
948 int result;
949 int fd;
950 char* mapAddress;
951
952 int vmid = os::current_process_id();
953
954 char* user_name = get_user_name(geteuid());
955
956 if (user_name == NULL)
957 return NULL;
958
959 char* dirname = get_user_tmp_dir(user_name);
960 char* filename = get_sharedmem_filename(dirname, vmid);
961
962 // get the short filename
963 char* short_filename = strrchr(filename, '/');
964 if (short_filename == NULL) {
965 short_filename = filename;
966 } else {
967 short_filename++;
968 }
969
970 // cleanup any stale shared memory files
971 cleanup_sharedmem_resources(dirname);
972
973 assert(((size > 0) && (size % os::vm_page_size() == 0)),
974 "unexpected PerfMemory region size");
975
976 fd = create_sharedmem_resources(dirname, short_filename, size);
977
978 FREE_C_HEAP_ARRAY(char, user_name, mtInternal);
979 FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
980
981 if (fd == -1) {
982 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
983 return NULL;
984 }
985
986 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
987
988 result = ::close(fd);
989 assert(result != OS_ERR, "could not close file");
990
991 if (mapAddress == MAP_FAILED) {
992 if (PrintMiscellaneous && Verbose) {
993 warning("mmap failed - %s\n", strerror(errno));
994 }
995 remove_file(filename);
996 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
997 return NULL;
998 }
999
1000 // save the file name for use in delete_shared_memory()
1001 backing_store_file_name = filename;
1002
1003 // clear the shared memory region
1004 (void)::memset((void*) mapAddress, 0, size);
1005
1006 // it does not go through os api, the operation has to record from here
1007 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress,
1008 size, CURRENT_PC, mtInternal);
1009
1010 return mapAddress;
1011 }
1012
1013 // release a named shared memory region
1014 //
1015 static void unmap_shared(char* addr, size_t bytes) {
1016 os::release_memory(addr, bytes);
1017 }
1018
1019 // create the PerfData memory region in shared memory.
1020 //
1021 static char* create_shared_memory(size_t size) {
1022
1023 // create the shared memory region.
1024 return mmap_create_shared(size);
1025 }
1026
1027 // delete the shared PerfData memory region
1028 //
1029 static void delete_shared_memory(char* addr, size_t size) {
1030
1031 // cleanup the persistent shared memory resources. since DestroyJavaVM does
1032 // not support unloading of the JVM, unmapping of the memory resource is
1033 // not performed. The memory will be reclaimed by the OS upon termination of
1034 // the process. The backing store file is deleted from the file system.
1035
1036 assert(!PerfDisableSharedMem, "shouldn't be here");
1037
1038 if (backing_store_file_name != NULL) {
1039 remove_file(backing_store_file_name);
1040 // Don't.. Free heap memory could deadlock os::abort() if it is called
1041 // from signal handler. OS will reclaim the heap memory.
1042 // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
1043 backing_store_file_name = NULL;
1044 }
1045 }
1046
1047 // return the size of the file for the given file descriptor
1048 // or 0 if it is not a valid size for a shared memory file
1049 //
1050 static size_t sharedmem_filesize(int fd, TRAPS) {
1051
1052 struct stat statbuf;
1053 int result;
1054
1055 RESTARTABLE(::fstat(fd, &statbuf), result);
1056 if (result == OS_ERR) {
1057 if (PrintMiscellaneous && Verbose) {
1058 warning("fstat failed: %s\n", strerror(errno));
1059 }
1060 THROW_MSG_0(vmSymbols::java_io_IOException(),
1061 "Could not determine PerfMemory size");
1062 }
1063
1064 if ((statbuf.st_size == 0) ||
1065 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
1066 THROW_MSG_0(vmSymbols::java_lang_Exception(),
1067 "Invalid PerfMemory size");
1068 }
1069
1070 return (size_t)statbuf.st_size;
1071 }
1072
1073 // attach to a named shared memory region.
1074 //
1075 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
1076
1077 char* mapAddress;
1078 int result;
1079 int fd;
1080 size_t size = 0;
1081 const char* luser = NULL;
1082
1083 int mmap_prot;
1084 int file_flags;
1085
1086 ResourceMark rm;
1087
1088 // map the high level access mode to the appropriate permission
1089 // constructs for the file and the shared memory mapping.
1090 if (mode == PerfMemory::PERF_MODE_RO) {
1091 mmap_prot = PROT_READ;
1092 file_flags = O_RDONLY | O_NOFOLLOW;
1093 }
1094 else if (mode == PerfMemory::PERF_MODE_RW) {
1095 #ifdef LATER
1096 mmap_prot = PROT_READ | PROT_WRITE;
1097 file_flags = O_RDWR | O_NOFOLLOW;
1098 #else
1099 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1100 "Unsupported access mode");
1101 #endif
1102 }
1103 else {
1104 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1105 "Illegal access mode");
1106 }
1107
1108 if (user == NULL || strlen(user) == 0) {
1109 luser = get_user_name(vmid, CHECK);
1110 }
1111 else {
1112 luser = user;
1113 }
1114
1115 if (luser == NULL) {
1116 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1117 "Could not map vmid to user Name");
1118 }
1119
1120 char* dirname = get_user_tmp_dir(luser);
1121
1122 // since we don't follow symbolic links when creating the backing
1123 // store file, we don't follow them when attaching either.
1124 //
1125 if (!is_directory_secure(dirname)) {
1126 FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
1127 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1128 "Process not found");
1129 }
1130
1131 char* filename = get_sharedmem_filename(dirname, vmid);
1132
1133 // copy heap memory to resource memory. the open_sharedmem_file
1134 // method below need to use the filename, but could throw an
1135 // exception. using a resource array prevents the leak that
1136 // would otherwise occur.
1137 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
1138 strcpy(rfilename, filename);
1139
1140 // free the c heap resources that are no longer needed
1141 if (luser != user) FREE_C_HEAP_ARRAY(char, luser, mtInternal);
1142 FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
1143 FREE_C_HEAP_ARRAY(char, filename, mtInternal);
1144
1145 // open the shared memory file for the give vmid
1146 fd = open_sharedmem_file(rfilename, file_flags, THREAD);
1147
1148 if (fd == OS_ERR) {
1149 return;
1150 }
1151
1152 if (HAS_PENDING_EXCEPTION) {
1153 ::close(fd);
1154 return;
1155 }
1156
1157 if (*sizep == 0) {
1158 size = sharedmem_filesize(fd, CHECK);
1159 } else {
1160 size = *sizep;
1161 }
1162
1163 assert(size > 0, "unexpected size <= 0");
1164
1165 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
1166
1167 result = ::close(fd);
1168 assert(result != OS_ERR, "could not close file");
1169
1170 if (mapAddress == MAP_FAILED) {
1171 if (PrintMiscellaneous && Verbose) {
1172 warning("mmap failed: %s\n", strerror(errno));
1173 }
1174 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
1175 "Could not map PerfMemory");
1176 }
1177
1178 // it does not go through os api, the operation has to record from here
1179 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress,
1180 size, CURRENT_PC, mtInternal);
1181
1182 *addr = mapAddress;
1183 *sizep = size;
1184
1185 if (PerfTraceMemOps) {
1186 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
1187 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress);
1188 }
1189 }
1190
1191
1192
1193
1194 // create the PerfData memory region
1195 //
1196 // This method creates the memory region used to store performance
1197 // data for the JVM. The memory may be created in standard or
1198 // shared memory.
1199 //
1200 void PerfMemory::create_memory_region(size_t size) {
1201
1202 if (PerfDisableSharedMem) {
1203 // do not share the memory for the performance data.
1204 _start = create_standard_memory(size);
1205 }
1206 else {
1207 _start = create_shared_memory(size);
1208 if (_start == NULL) {
1209
1210 // creation of the shared memory region failed, attempt
1211 // to create a contiguous, non-shared memory region instead.
1212 //
1213 if (PrintMiscellaneous && Verbose) {
1214 warning("Reverting to non-shared PerfMemory region.\n");
1215 }
1216 PerfDisableSharedMem = true;
1217 _start = create_standard_memory(size);
1218 }
1219 }
1220
1221 if (_start != NULL) _capacity = size;
1222
1223 }
1224
1225 // delete the PerfData memory region
1226 //
1227 // This method deletes the memory region used to store performance
1228 // data for the JVM. The memory region indicated by the <address, size>
1229 // tuple will be inaccessible after a call to this method.
1230 //
1231 void PerfMemory::delete_memory_region() {
1232
1233 assert((start() != NULL && capacity() > 0), "verify proper state");
1234
1235 // If user specifies PerfDataSaveFile, it will save the performance data
1236 // to the specified file name no matter whether PerfDataSaveToFile is specified
1237 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
1238 // -XX:+PerfDataSaveToFile.
1239 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
1240 save_memory_to_file(start(), capacity());
1241 }
1242
1243 if (PerfDisableSharedMem) {
1244 delete_standard_memory(start(), capacity());
1245 }
1246 else {
1247 delete_shared_memory(start(), capacity());
1248 }
1249 }
1250
1251 // attach to the PerfData memory region for another JVM
1252 //
1253 // This method returns an <address, size> tuple that points to
1254 // a memory buffer that is kept reasonably synchronized with
1255 // the PerfData memory region for the indicated JVM. This
1256 // buffer may be kept in synchronization via shared memory
1257 // or some other mechanism that keeps the buffer updated.
1258 //
1259 // If the JVM chooses not to support the attachability feature,
1260 // this method should throw an UnsupportedOperation exception.
1261 //
1262 // This implementation utilizes named shared memory to map
1263 // the indicated process's PerfData memory region into this JVMs
1264 // address space.
1265 //
1266 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
1267
1268 if (vmid == 0 || vmid == os::current_process_id()) {
1269 *addrp = start();
1270 *sizep = capacity();
1271 return;
1272 }
1273
1274 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
1275 }
1276
1277 // detach from the PerfData memory region of another JVM
1278 //
1279 // This method detaches the PerfData memory region of another
1280 // JVM, specified as an <address, size> tuple of a buffer
1281 // in this process's address space. This method may perform
1282 // arbitrary actions to accomplish the detachment. The memory
1283 // region specified by <address, size> will be inaccessible after
1284 // a call to this method.
1285 //
1286 // If the JVM chooses not to support the attachability feature,
1287 // this method should throw an UnsupportedOperation exception.
1288 //
1289 // This implementation utilizes named shared memory to detach
1290 // the indicated process's PerfData memory region from this
1291 // process's address space.
1292 //
1293 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1294
1295 assert(addr != 0, "address sanity check");
1296 assert(bytes > 0, "capacity sanity check");
1297
1298 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1299 // prevent accidental detachment of this process's PerfMemory region
1300 return;
1301 }
1302
1303 unmap_shared(addr, bytes);
1304 }
1305
1306 char* PerfMemory::backing_store_filename() {
1307 return backing_store_file_name;
1308 }