1 /*
2 * Copyright (c) 2001, 2014, 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);
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 // See if the uid of the directory matches the effective uid of the process.
223 //
224 if (statp->st_uid != geteuid()) {
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.
381 result = fchdir(fd);
382
383 return dirp;
384 }
385
386 // Close the directory and restore the current working directory.
387 //
388 static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) {
389
390 int result;
391 // If we have a saved cwd change back to it and close the fd.
392 if (saved_cwd_fd != -1) {
393 result = fchdir(saved_cwd_fd);
394 ::close(saved_cwd_fd);
395 }
396
397 // Close the directory.
398 os::closedir(dirp);
399 }
400
401 // Check if the given file descriptor is considered a secure.
402 //
403 static bool is_file_secure(int fd, const char *filename) {
404
405 int result;
406 struct stat statbuf;
407
408 // Determine if the file is secure.
409 RESTARTABLE(::fstat(fd, &statbuf), result);
410 if (result == OS_ERR) {
411 if (PrintMiscellaneous && Verbose) {
412 warning("fstat failed on %s: %s\n", filename, strerror(errno));
413 }
414 return false;
415 }
416 if (statbuf.st_nlink > 1) {
417 // A file with multiple links is not expected.
418 if (PrintMiscellaneous && Verbose) {
419 warning("file %s has multiple links\n", filename);
420 }
421 return false;
422 }
423 return true;
424 }
425
426 // return the user name for the given user id
427 //
428 // the caller is expected to free the allocated memory.
429 //
430 static char* get_user_name(uid_t uid) {
431
432 struct passwd pwent;
433
434 // determine the max pwbuf size from sysconf, and hardcode
435 // a default if this not available through sysconf.
436 //
437 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
438 if (bufsize == -1)
439 bufsize = 1024;
440
441 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
442
443 #ifdef _GNU_SOURCE
444 struct passwd* p = NULL;
445 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);
446 #else // _GNU_SOURCE
447 struct passwd* p = getpwuid_r(uid, &pwent, pwbuf, (int)bufsize);
448 #endif // _GNU_SOURCE
449
450 if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {
451 if (PrintMiscellaneous && Verbose) {
452 if (p == NULL) {
453 warning("Could not retrieve passwd entry: %s\n",
454 strerror(errno));
455 }
456 else {
457 warning("Could not determine user name: %s\n",
458 p->pw_name == NULL ? "pw_name = NULL" :
459 "pw_name zero length");
460 }
461 }
462 FREE_C_HEAP_ARRAY(char, pwbuf);
463 return NULL;
464 }
465
466 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal);
467 strcpy(user_name, p->pw_name);
468
469 FREE_C_HEAP_ARRAY(char, pwbuf);
470 return user_name;
471 }
472
473 // return the name of the user that owns the process identified by vmid.
474 //
475 // This method uses a slow directory search algorithm to find the backing
476 // store file for the specified vmid and returns the user name, as determined
477 // by the user name suffix of the hsperfdata_<username> directory name.
478 //
479 // the caller is expected to free the allocated memory.
480 //
481 static char* get_user_name_slow(int vmid, TRAPS) {
482
483 // short circuit the directory search if the process doesn't even exist.
484 if (kill(vmid, 0) == OS_ERR) {
485 if (errno == ESRCH) {
486 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
487 "Process not found");
488 }
489 else /* EPERM */ {
490 THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno));
491 }
492 }
493
494 // directory search
495 char* oldest_user = NULL;
496 time_t oldest_ctime = 0;
497
498 const char* tmpdirname = os::get_temp_directory();
499
500 // open the temp directory
501 DIR* tmpdirp = os::opendir(tmpdirname);
502
503 if (tmpdirp == NULL) {
504 // Cannot open the directory to get the user name, return.
505 return NULL;
506 }
507
508 // for each entry in the directory that matches the pattern hsperfdata_*,
509 // open the directory and check if the file for the given vmid exists.
510 // The file with the expected name and the latest creation date is used
511 // to determine the user name for the process id.
512 //
513 struct dirent* dentry;
514 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
515 errno = 0;
516 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) {
517
518 // check if the directory entry is a hsperfdata file
519 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
520 continue;
521 }
522
523 char* usrdir_name = NEW_C_HEAP_ARRAY(char,
524 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
525 strcpy(usrdir_name, tmpdirname);
526 strcat(usrdir_name, "/");
527 strcat(usrdir_name, dentry->d_name);
528
529 // open the user directory
530 DIR* subdirp = open_directory_secure(usrdir_name);
531
532 if (subdirp == NULL) {
533 FREE_C_HEAP_ARRAY(char, usrdir_name);
534 continue;
535 }
536
537 // Since we don't create the backing store files in directories
538 // pointed to by symbolic links, we also don't follow them when
539 // looking for the files. We check for a symbolic link after the
540 // call to opendir in order to eliminate a small window where the
541 // symlink can be exploited.
542 //
543 if (!is_directory_secure(usrdir_name)) {
544 FREE_C_HEAP_ARRAY(char, usrdir_name);
545 os::closedir(subdirp);
546 continue;
547 }
548
549 struct dirent* udentry;
550 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
551 errno = 0;
552 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
553
554 if (filename_to_pid(udentry->d_name) == vmid) {
555 struct stat statbuf;
556 int result;
557
558 char* filename = NEW_C_HEAP_ARRAY(char,
559 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
560
561 strcpy(filename, usrdir_name);
562 strcat(filename, "/");
563 strcat(filename, udentry->d_name);
564
565 // don't follow symbolic links for the file
566 RESTARTABLE(::lstat(filename, &statbuf), result);
567 if (result == OS_ERR) {
568 FREE_C_HEAP_ARRAY(char, filename);
569 continue;
570 }
571
572 // skip over files that are not regular files.
573 if (!S_ISREG(statbuf.st_mode)) {
574 FREE_C_HEAP_ARRAY(char, filename);
575 continue;
576 }
577
578 // compare and save filename with latest creation time
579 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
580
581 if (statbuf.st_ctime > oldest_ctime) {
582 char* user = strchr(dentry->d_name, '_') + 1;
583
584 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user);
585 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal);
586
587 strcpy(oldest_user, user);
588 oldest_ctime = statbuf.st_ctime;
589 }
590 }
591
592 FREE_C_HEAP_ARRAY(char, filename);
593 }
594 }
595 os::closedir(subdirp);
596 FREE_C_HEAP_ARRAY(char, udbuf);
597 FREE_C_HEAP_ARRAY(char, usrdir_name);
598 }
599 os::closedir(tmpdirp);
600 FREE_C_HEAP_ARRAY(char, tdbuf);
601
602 return(oldest_user);
603 }
604
605 // return the name of the user that owns the JVM indicated by the given vmid.
606 //
607 static char* get_user_name(int vmid, TRAPS) {
608
609 char psinfo_name[PATH_MAX];
610 int result;
611
612 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid);
613
614 RESTARTABLE(::open(psinfo_name, O_RDONLY), result);
615
616 if (result != OS_ERR) {
617 int fd = result;
618
619 psinfo_t psinfo;
620 char* addr = (char*)&psinfo;
621
622 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) {
623
624 RESTARTABLE(::read(fd, addr, remaining), result);
625 if (result == OS_ERR) {
626 ::close(fd);
627 THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error");
628 } else {
629 remaining-=result;
630 addr+=result;
631 }
632 }
633
634 ::close(fd);
635
636 // get the user name for the effective user id of the process
637 char* user_name = get_user_name(psinfo.pr_euid);
638
639 return user_name;
640 }
641
642 if (result == OS_ERR && errno == EACCES) {
643
644 // In this case, the psinfo file for the process id existed,
645 // but we didn't have permission to access it.
646 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
647 strerror(errno));
648 }
649
650 // at this point, we don't know if the process id itself doesn't
651 // exist or if the psinfo file doesn't exit. If the psinfo file
652 // doesn't exist, then we are running on Solaris 2.5.1 or earlier.
653 // since the structured procfs and old procfs interfaces can't be
654 // mixed, we attempt to find the file through a directory search.
655
656 return get_user_name_slow(vmid, THREAD);
657 }
658
659 // return the file name of the backing store file for the named
660 // shared memory region for the given user name and vmid.
661 //
662 // the caller is expected to free the allocated memory.
663 //
664 static char* get_sharedmem_filename(const char* dirname, int vmid) {
665
666 // add 2 for the file separator and a NULL terminator.
667 size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
668
669 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
670 snprintf(name, nbytes, "%s/%d", dirname, vmid);
671
672 return name;
673 }
674
675
676 // remove file
677 //
678 // this method removes the file specified by the given path
679 //
680 static void remove_file(const char* path) {
681
682 int result;
683
684 // if the file is a directory, the following unlink will fail. since
685 // we don't expect to find directories in the user temp directory, we
686 // won't try to handle this situation. even if accidentially or
687 // maliciously planted, the directory's presence won't hurt anything.
688 //
689 RESTARTABLE(::unlink(path), result);
690 if (PrintMiscellaneous && Verbose && result == OS_ERR) {
691 if (errno != ENOENT) {
692 warning("Could not unlink shared memory backing"
693 " store file %s : %s\n", path, strerror(errno));
694 }
695 }
696 }
697
698
699 // cleanup stale shared memory resources
700 //
701 // This method attempts to remove all stale shared memory files in
702 // the named user temporary directory. It scans the named directory
703 // for files matching the pattern ^$[0-9]*$. For each file found, the
704 // process id is extracted from the file name and a test is run to
705 // determine if the process is alive. If the process is not alive,
706 // any stale file resources are removed.
707 //
708 static void cleanup_sharedmem_resources(const char* dirname) {
709
710 int saved_cwd_fd;
711 // open the directory
712 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
713 if (dirp == NULL) {
714 // directory doesn't exist or is insecure, so there is nothing to cleanup
715 return;
716 }
717
718 // for each entry in the directory that matches the expected file
719 // name pattern, determine if the file resources are stale and if
720 // so, remove the file resources. Note, instrumented HotSpot processes
721 // for this user may start and/or terminate during this search and
722 // remove or create new files in this directory. The behavior of this
723 // loop under these conditions is dependent upon the implementation of
724 // opendir/readdir.
725 //
726 struct dirent* entry;
727 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
728
729 errno = 0;
730 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
731
732 pid_t pid = filename_to_pid(entry->d_name);
733
734 if (pid == 0) {
735
736 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
737
738 // attempt to remove all unexpected files, except "." and ".."
739 unlink(entry->d_name);
740 }
741
742 errno = 0;
743 continue;
744 }
745
746 // we now have a file name that converts to a valid integer
747 // that could represent a process id . if this process id
748 // matches the current process id or the process is not running,
749 // then remove the stale file resources.
750 //
751 // process liveness is detected by sending signal number 0 to
752 // the process id (see kill(2)). if kill determines that the
753 // process does not exist, then the file resources are removed.
754 // if kill determines that that we don't have permission to
755 // signal the process, then the file resources are assumed to
756 // be stale and are removed because the resources for such a
757 // process should be in a different user specific directory.
758 //
759 if ((pid == os::current_process_id()) ||
760 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
761
762 unlink(entry->d_name);
763 }
764 errno = 0;
765 }
766
767 // close the directory and reset the current working directory
768 close_directory_secure_cwd(dirp, saved_cwd_fd);
769
770 FREE_C_HEAP_ARRAY(char, dbuf);
771 }
772
773 // make the user specific temporary directory. Returns true if
774 // the directory exists and is secure upon return. Returns false
775 // if the directory exists but is either a symlink, is otherwise
776 // insecure, or if an error occurred.
777 //
778 static bool make_user_tmp_dir(const char* dirname) {
779
780 // create the directory with 0755 permissions. note that the directory
781 // will be owned by euid::egid, which may not be the same as uid::gid.
782 //
783 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
784 if (errno == EEXIST) {
785 // The directory already exists and was probably created by another
786 // JVM instance. However, this could also be the result of a
787 // deliberate symlink. Verify that the existing directory is safe.
788 //
789 if (!is_directory_secure(dirname)) {
790 // directory is not secure
791 if (PrintMiscellaneous && Verbose) {
792 warning("%s directory is insecure\n", dirname);
793 }
794 return false;
795 }
796 }
797 else {
798 // we encountered some other failure while attempting
799 // to create the directory
800 //
801 if (PrintMiscellaneous && Verbose) {
802 warning("could not create directory %s: %s\n",
803 dirname, strerror(errno));
804 }
805 return false;
806 }
807 }
808 return true;
809 }
810
811 // create the shared memory file resources
812 //
813 // This method creates the shared memory file with the given size
814 // This method also creates the user specific temporary directory, if
815 // it does not yet exist.
816 //
817 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
818
819 // make the user temporary directory
820 if (!make_user_tmp_dir(dirname)) {
821 // could not make/find the directory or the found directory
822 // was not secure
823 return -1;
824 }
825
826 int saved_cwd_fd;
827 // open the directory and set the current working directory to it
828 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
829 if (dirp == NULL) {
830 // Directory doesn't exist or is insecure, so cannot create shared
831 // memory file.
832 return -1;
833 }
834
835 // Open the filename in the current directory.
836 // Cannot use O_TRUNC here; truncation of an existing file has to happen
837 // after the is_file_secure() check below.
838 int result;
839 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result);
840 if (result == OS_ERR) {
841 if (PrintMiscellaneous && Verbose) {
842 if (errno == ELOOP) {
843 warning("file %s is a symlink and is not secure\n", filename);
844 } else {
845 warning("could not create file %s: %s\n", filename, strerror(errno));
846 }
847 }
848 // close the directory and reset the current working directory
849 close_directory_secure_cwd(dirp, saved_cwd_fd);
850
851 return -1;
852 }
853 // close the directory and reset the current working directory
854 close_directory_secure_cwd(dirp, saved_cwd_fd);
855
856 // save the file descriptor
857 int fd = result;
858
859 // check to see if the file is secure
860 if (!is_file_secure(fd, filename)) {
861 ::close(fd);
862 return -1;
863 }
864
865 // truncate the file to get rid of any existing data
866 RESTARTABLE(::ftruncate(fd, (off_t)0), result);
867 if (result == OS_ERR) {
868 if (PrintMiscellaneous && Verbose) {
869 warning("could not truncate shared memory file: %s\n", strerror(errno));
870 }
871 ::close(fd);
872 return -1;
873 }
874 // set the file size
875 RESTARTABLE(::ftruncate(fd, (off_t)size), result);
876 if (result == OS_ERR) {
877 if (PrintMiscellaneous && Verbose) {
878 warning("could not set shared memory file size: %s\n", strerror(errno));
879 }
880 ::close(fd);
881 return -1;
882 }
883
884 return fd;
885 }
886
887 // open the shared memory file for the given user and vmid. returns
888 // the file descriptor for the open file or -1 if the file could not
889 // be opened.
890 //
891 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
892
893 // open the file
894 int result;
895 RESTARTABLE(::open(filename, oflags), result);
896 if (result == OS_ERR) {
897 if (errno == ENOENT) {
898 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
899 "Process not found", OS_ERR);
900 }
901 else if (errno == EACCES) {
902 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
903 "Permission denied", OS_ERR);
904 }
905 else {
906 THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR);
907 }
908 }
909 int fd = result;
910
911 // check to see if the file is secure
912 if (!is_file_secure(fd, filename)) {
913 ::close(fd);
914 return -1;
915 }
916
917 return fd;
918 }
919
920 // create a named shared memory region. returns the address of the
921 // memory region on success or NULL on failure. A return value of
922 // NULL will ultimately disable the shared memory feature.
923 //
924 // On Solaris and Linux, the name space for shared memory objects
925 // is the file system name space.
926 //
927 // A monitoring application attaching to a JVM does not need to know
928 // the file system name of the shared memory object. However, it may
929 // be convenient for applications to discover the existence of newly
930 // created and terminating JVMs by watching the file system name space
931 // for files being created or removed.
932 //
933 static char* mmap_create_shared(size_t size) {
934
935 int result;
936 int fd;
937 char* mapAddress;
938
939 int vmid = os::current_process_id();
940
941 char* user_name = get_user_name(geteuid());
942
943 if (user_name == NULL)
944 return NULL;
945
946 char* dirname = get_user_tmp_dir(user_name);
947 char* filename = get_sharedmem_filename(dirname, vmid);
948
949 // get the short filename
950 char* short_filename = strrchr(filename, '/');
951 if (short_filename == NULL) {
952 short_filename = filename;
953 } else {
954 short_filename++;
955 }
956
957 // cleanup any stale shared memory files
958 cleanup_sharedmem_resources(dirname);
959
960 assert(((size > 0) && (size % os::vm_page_size() == 0)),
961 "unexpected PerfMemory region size");
962
963 fd = create_sharedmem_resources(dirname, short_filename, size);
964
965 FREE_C_HEAP_ARRAY(char, user_name);
966 FREE_C_HEAP_ARRAY(char, dirname);
967
968 if (fd == -1) {
969 FREE_C_HEAP_ARRAY(char, filename);
970 return NULL;
971 }
972
973 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
974
975 result = ::close(fd);
976 assert(result != OS_ERR, "could not close file");
977
978 if (mapAddress == MAP_FAILED) {
979 if (PrintMiscellaneous && Verbose) {
980 warning("mmap failed - %s\n", strerror(errno));
981 }
982 remove_file(filename);
983 FREE_C_HEAP_ARRAY(char, filename);
984 return NULL;
985 }
986
987 // save the file name for use in delete_shared_memory()
988 backing_store_file_name = filename;
989
990 // clear the shared memory region
991 (void)::memset((void*) mapAddress, 0, size);
992
993 // it does not go through os api, the operation has to record from here
994 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress,
995 size, CURRENT_PC, mtInternal);
996
997 return mapAddress;
998 }
999
1000 // release a named shared memory region
1001 //
1002 static void unmap_shared(char* addr, size_t bytes) {
1003 os::release_memory(addr, bytes);
1004 }
1005
1006 // create the PerfData memory region in shared memory.
1007 //
1008 static char* create_shared_memory(size_t size) {
1009
1010 // create the shared memory region.
1011 return mmap_create_shared(size);
1012 }
1013
1014 // delete the shared PerfData memory region
1015 //
1016 static void delete_shared_memory(char* addr, size_t size) {
1017
1018 // cleanup the persistent shared memory resources. since DestroyJavaVM does
1019 // not support unloading of the JVM, unmapping of the memory resource is
1020 // not performed. The memory will be reclaimed by the OS upon termination of
1021 // the process. The backing store file is deleted from the file system.
1022
1023 assert(!PerfDisableSharedMem, "shouldn't be here");
1024
1025 if (backing_store_file_name != NULL) {
1026 remove_file(backing_store_file_name);
1027 // Don't.. Free heap memory could deadlock os::abort() if it is called
1028 // from signal handler. OS will reclaim the heap memory.
1029 // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
1030 backing_store_file_name = NULL;
1031 }
1032 }
1033
1034 // return the size of the file for the given file descriptor
1035 // or 0 if it is not a valid size for a shared memory file
1036 //
1037 static size_t sharedmem_filesize(int fd, TRAPS) {
1038
1039 struct stat statbuf;
1040 int result;
1041
1042 RESTARTABLE(::fstat(fd, &statbuf), result);
1043 if (result == OS_ERR) {
1044 if (PrintMiscellaneous && Verbose) {
1045 warning("fstat failed: %s\n", strerror(errno));
1046 }
1047 THROW_MSG_0(vmSymbols::java_io_IOException(),
1048 "Could not determine PerfMemory size");
1049 }
1050
1051 if ((statbuf.st_size == 0) ||
1052 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
1053 THROW_MSG_0(vmSymbols::java_lang_Exception(),
1054 "Invalid PerfMemory size");
1055 }
1056
1057 return (size_t)statbuf.st_size;
1058 }
1059
1060 // attach to a named shared memory region.
1061 //
1062 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
1063
1064 char* mapAddress;
1065 int result;
1066 int fd;
1067 size_t size = 0;
1068 const char* luser = NULL;
1069
1070 int mmap_prot;
1071 int file_flags;
1072
1073 ResourceMark rm;
1074
1075 // map the high level access mode to the appropriate permission
1076 // constructs for the file and the shared memory mapping.
1077 if (mode == PerfMemory::PERF_MODE_RO) {
1078 mmap_prot = PROT_READ;
1079 file_flags = O_RDONLY | O_NOFOLLOW;
1080 }
1081 else if (mode == PerfMemory::PERF_MODE_RW) {
1082 #ifdef LATER
1083 mmap_prot = PROT_READ | PROT_WRITE;
1084 file_flags = O_RDWR | O_NOFOLLOW;
1085 #else
1086 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1087 "Unsupported access mode");
1088 #endif
1089 }
1090 else {
1091 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1092 "Illegal access mode");
1093 }
1094
1095 if (user == NULL || strlen(user) == 0) {
1096 luser = get_user_name(vmid, CHECK);
1097 }
1098 else {
1099 luser = user;
1100 }
1101
1102 if (luser == NULL) {
1103 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1104 "Could not map vmid to user Name");
1105 }
1106
1107 char* dirname = get_user_tmp_dir(luser);
1108
1109 // since we don't follow symbolic links when creating the backing
1110 // store file, we don't follow them when attaching either.
1111 //
1112 if (!is_directory_secure(dirname)) {
1113 FREE_C_HEAP_ARRAY(char, dirname);
1114 if (luser != user) {
1115 FREE_C_HEAP_ARRAY(char, luser);
1116 }
1117 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1118 "Process not found");
1119 }
1120
1121 char* filename = get_sharedmem_filename(dirname, vmid);
1122
1123 // copy heap memory to resource memory. the open_sharedmem_file
1124 // method below need to use the filename, but could throw an
1125 // exception. using a resource array prevents the leak that
1126 // would otherwise occur.
1127 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
1128 strcpy(rfilename, filename);
1129
1130 // free the c heap resources that are no longer needed
1131 if (luser != user) FREE_C_HEAP_ARRAY(char, luser);
1132 FREE_C_HEAP_ARRAY(char, dirname);
1133 FREE_C_HEAP_ARRAY(char, filename);
1134
1135 // open the shared memory file for the give vmid
1136 fd = open_sharedmem_file(rfilename, file_flags, THREAD);
1137
1138 if (fd == OS_ERR) {
1139 return;
1140 }
1141
1142 if (HAS_PENDING_EXCEPTION) {
1143 ::close(fd);
1144 return;
1145 }
1146
1147 if (*sizep == 0) {
1148 size = sharedmem_filesize(fd, CHECK);
1149 } else {
1150 size = *sizep;
1151 }
1152
1153 assert(size > 0, "unexpected size <= 0");
1154
1155 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
1156
1157 result = ::close(fd);
1158 assert(result != OS_ERR, "could not close file");
1159
1160 if (mapAddress == MAP_FAILED) {
1161 if (PrintMiscellaneous && Verbose) {
1162 warning("mmap failed: %s\n", strerror(errno));
1163 }
1164 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
1165 "Could not map PerfMemory");
1166 }
1167
1168 // it does not go through os api, the operation has to record from here
1169 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress,
1170 size, CURRENT_PC, mtInternal);
1171
1172 *addr = mapAddress;
1173 *sizep = size;
1174
1175 if (PerfTraceMemOps) {
1176 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
1177 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress);
1178 }
1179 }
1180
1181
1182
1183
1184 // create the PerfData memory region
1185 //
1186 // This method creates the memory region used to store performance
1187 // data for the JVM. The memory may be created in standard or
1188 // shared memory.
1189 //
1190 void PerfMemory::create_memory_region(size_t size) {
1191
1192 if (PerfDisableSharedMem) {
1193 // do not share the memory for the performance data.
1194 _start = create_standard_memory(size);
1195 }
1196 else {
1197 _start = create_shared_memory(size);
1198 if (_start == NULL) {
1199
1200 // creation of the shared memory region failed, attempt
1201 // to create a contiguous, non-shared memory region instead.
1202 //
1203 if (PrintMiscellaneous && Verbose) {
1204 warning("Reverting to non-shared PerfMemory region.\n");
1205 }
1206 PerfDisableSharedMem = true;
1207 _start = create_standard_memory(size);
1208 }
1209 }
1210
1211 if (_start != NULL) _capacity = size;
1212
1213 }
1214
1215 // delete the PerfData memory region
1216 //
1217 // This method deletes the memory region used to store performance
1218 // data for the JVM. The memory region indicated by the <address, size>
1219 // tuple will be inaccessible after a call to this method.
1220 //
1221 void PerfMemory::delete_memory_region() {
1222
1223 assert((start() != NULL && capacity() > 0), "verify proper state");
1224
1225 // If user specifies PerfDataSaveFile, it will save the performance data
1226 // to the specified file name no matter whether PerfDataSaveToFile is specified
1227 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
1228 // -XX:+PerfDataSaveToFile.
1229 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
1230 save_memory_to_file(start(), capacity());
1231 }
1232
1233 if (PerfDisableSharedMem) {
1234 delete_standard_memory(start(), capacity());
1235 }
1236 else {
1237 delete_shared_memory(start(), capacity());
1238 }
1239 }
1240
1241 // attach to the PerfData memory region for another JVM
1242 //
1243 // This method returns an <address, size> tuple that points to
1244 // a memory buffer that is kept reasonably synchronized with
1245 // the PerfData memory region for the indicated JVM. This
1246 // buffer may be kept in synchronization via shared memory
1247 // or some other mechanism that keeps the buffer updated.
1248 //
1249 // If the JVM chooses not to support the attachability feature,
1250 // this method should throw an UnsupportedOperation exception.
1251 //
1252 // This implementation utilizes named shared memory to map
1253 // the indicated process's PerfData memory region into this JVMs
1254 // address space.
1255 //
1256 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
1257
1258 if (vmid == 0 || vmid == os::current_process_id()) {
1259 *addrp = start();
1260 *sizep = capacity();
1261 return;
1262 }
1263
1264 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
1265 }
1266
1267 // detach from the PerfData memory region of another JVM
1268 //
1269 // This method detaches the PerfData memory region of another
1270 // JVM, specified as an <address, size> tuple of a buffer
1271 // in this process's address space. This method may perform
1272 // arbitrary actions to accomplish the detachment. The memory
1273 // region specified by <address, size> will be inaccessible after
1274 // a call to this method.
1275 //
1276 // If the JVM chooses not to support the attachability feature,
1277 // this method should throw an UnsupportedOperation exception.
1278 //
1279 // This implementation utilizes named shared memory to detach
1280 // the indicated process's PerfData memory region from this
1281 // process's address space.
1282 //
1283 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1284
1285 assert(addr != 0, "address sanity check");
1286 assert(bytes > 0, "capacity sanity check");
1287
1288 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1289 // prevent accidental detachment of this process's PerfMemory region
1290 return;
1291 }
1292
1293 unmap_shared(addr, bytes);
1294 }