1 /*
2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/vmSymbols.hpp"
27 #include "logging/log.hpp"
28 #include "memory/allocation.inline.hpp"
29 #include "memory/resourceArea.hpp"
30 #include "oops/oop.inline.hpp"
31 #include "os_solaris.inline.hpp"
32 #include "runtime/handles.inline.hpp"
33 #include "runtime/perfMemory.hpp"
34 #include "services/memTracker.hpp"
35 #include "utilities/exceptions.hpp"
36
37 // put OS-includes here
38 #include <sys/types.h>
39 #include <sys/mman.h>
40 #include <errno.h>
41 #include <stdio.h>
42 #include <unistd.h>
43 #include <sys/stat.h>
44 #include <signal.h>
45 #include <procfs.h>
46
47 /* For POSIX-compliant getpwuid_r on Solaris */
48 #define _POSIX_PTHREAD_SEMANTICS
49 #include <pwd.h>
50
51 static char* backing_store_file_name = NULL; // name of the backing store
52 // file, if successfully created.
53
54 // Standard Memory Implementation Details
55
56 // create the PerfData memory region in standard memory.
57 //
58 static char* create_standard_memory(size_t size) {
59
60 // allocate an aligned chuck of memory
61 char* mapAddress = os::reserve_memory(size);
62
63 if (mapAddress == NULL) {
64 return NULL;
65 }
66
67 // commit memory
68 if (!os::commit_memory(mapAddress, size, !ExecMem)) {
69 if (PrintMiscellaneous && Verbose) {
70 warning("Could not commit PerfData memory\n");
71 }
72 os::release_memory(mapAddress, size);
73 return NULL;
74 }
75
76 return mapAddress;
77 }
78
79 // delete the PerfData memory region
80 //
81 static void delete_standard_memory(char* addr, size_t size) {
82
83 // there are no persistent external resources to cleanup for standard
84 // memory. since DestroyJavaVM does not support unloading of the JVM,
85 // cleanup of the memory resource is not performed. The memory will be
86 // reclaimed by the OS upon termination of the process.
87 //
88 return;
89 }
90
91 // save the specified memory region to the given file
92 //
93 // Note: this function might be called from signal handler (by os::abort()),
94 // don't allocate heap memory.
95 //
96 static void save_memory_to_file(char* addr, size_t size) {
97
98 const char* destfile = PerfMemory::get_perfdata_file_path();
99 assert(destfile[0] != '\0', "invalid PerfData file path");
100
101 int result;
102
103 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE),
104 result);;
105 if (result == OS_ERR) {
106 if (PrintMiscellaneous && Verbose) {
107 warning("Could not create Perfdata save file: %s: %s\n",
108 destfile, os::strerror(errno));
109 }
110 } else {
111
112 int fd = result;
113
114 for (size_t remaining = size; remaining > 0;) {
115
116 RESTARTABLE(::write(fd, addr, remaining), result);
117 if (result == OS_ERR) {
118 if (PrintMiscellaneous && Verbose) {
119 warning("Could not write Perfdata save file: %s: %s\n",
120 destfile, os::strerror(errno));
121 }
122 break;
123 }
124 remaining -= (size_t)result;
125 addr += result;
126 }
127
128 result = ::close(fd);
129 if (PrintMiscellaneous && Verbose) {
130 if (result == OS_ERR) {
131 warning("Could not close %s: %s\n", destfile, os::strerror(errno));
132 }
133 }
134 }
135 FREE_C_HEAP_ARRAY(char, destfile);
136 }
137
138
139 // Shared Memory Implementation Details
140
141 // Note: the solaris and linux shared memory implementation uses the mmap
142 // interface with a backing store file to implement named shared memory.
143 // Using the file system as the name space for shared memory allows a
144 // common name space to be supported across a variety of platforms. It
145 // also provides a name space that Java applications can deal with through
146 // simple file apis.
147 //
148 // The solaris and linux implementations store the backing store file in
149 // a user specific temporary directory located in the /tmp file system,
150 // which is always a local file system and is sometimes a RAM based file
151 // system.
152
153 // return the user specific temporary directory name.
154 //
155 // the caller is expected to free the allocated memory.
156 //
157 static char* get_user_tmp_dir(const char* user) {
158
159 const char* tmpdir = os::get_temp_directory();
160 const char* perfdir = PERFDATA_NAME;
161 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3;
162 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
163
164 // construct the path name to user specific tmp directory
165 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user);
166
167 return dirname;
168 }
169
170 // convert the given file name into a process id. if the file
171 // does not meet the file naming constraints, return 0.
172 //
173 static pid_t filename_to_pid(const char* filename) {
174
175 // a filename that doesn't begin with a digit is not a
176 // candidate for conversion.
177 //
178 if (!isdigit(*filename)) {
179 return 0;
180 }
181
182 // check if file name can be converted to an integer without
183 // any leftover characters.
184 //
185 char* remainder = NULL;
186 errno = 0;
187 pid_t pid = (pid_t)strtol(filename, &remainder, 10);
188
189 if (errno != 0) {
190 return 0;
191 }
192
193 // check for left over characters. If any, then the filename is
194 // not a candidate for conversion.
195 //
196 if (remainder != NULL && *remainder != '\0') {
197 return 0;
198 }
199
200 // successful conversion, return the pid
201 return pid;
202 }
203
204
205 // Check if the given statbuf is considered a secure directory for
206 // the backing store files. Returns true if the directory is considered
207 // a secure location. Returns false if the statbuf is a symbolic link or
208 // if an error occurred.
209 //
210 static bool is_statbuf_secure(struct stat *statp) {
211 if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) {
212 // The path represents a link or some non-directory file type,
213 // which is not what we expected. Declare it insecure.
214 //
215 return false;
216 }
217 // We have an existing directory, check if the permissions are safe.
218 //
219 if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) {
220 // The directory is open for writing and could be subjected
221 // to a symlink or a hard link attack. Declare it insecure.
222 //
223 return false;
224 }
225 // If user is not root then see if the uid of the directory matches the effective uid of the process.
226 uid_t euid = geteuid();
227 if ((euid != 0) && (statp->st_uid != euid)) {
228 // The directory was not created by this user, declare it insecure.
229 //
230 return false;
231 }
232 return true;
233 }
234
235
236 // Check if the given path is considered a secure directory for
237 // the backing store files. Returns true if the directory exists
238 // and is considered a secure location. Returns false if the path
239 // is a symbolic link or if an error occurred.
240 //
241 static bool is_directory_secure(const char* path) {
242 struct stat statbuf;
243 int result = 0;
244
245 RESTARTABLE(::lstat(path, &statbuf), result);
246 if (result == OS_ERR) {
247 return false;
248 }
249
250 // The path exists, see if it is secure.
251 return is_statbuf_secure(&statbuf);
252 }
253
254
255 // Check if the given directory file descriptor is considered a secure
256 // directory for the backing store files. Returns true if the directory
257 // exists and is considered a secure location. Returns false if the path
258 // is a symbolic link or if an error occurred.
259 //
260 static bool is_dirfd_secure(int dir_fd) {
261 struct stat statbuf;
262 int result = 0;
263
264 RESTARTABLE(::fstat(dir_fd, &statbuf), result);
265 if (result == OS_ERR) {
266 return false;
267 }
268
269 // The path exists, now check its mode.
270 return is_statbuf_secure(&statbuf);
271 }
272
273
274 // Check to make sure fd1 and fd2 are referencing the same file system object.
275 //
276 static bool is_same_fsobject(int fd1, int fd2) {
277 struct stat statbuf1;
278 struct stat statbuf2;
279 int result = 0;
280
281 RESTARTABLE(::fstat(fd1, &statbuf1), result);
282 if (result == OS_ERR) {
283 return false;
284 }
285 RESTARTABLE(::fstat(fd2, &statbuf2), result);
286 if (result == OS_ERR) {
287 return false;
288 }
289
290 if ((statbuf1.st_ino == statbuf2.st_ino) &&
291 (statbuf1.st_dev == statbuf2.st_dev)) {
292 return true;
293 } else {
294 return false;
295 }
296 }
297
298
299 // Open the directory of the given path and validate it.
300 // Return a DIR * of the open directory.
301 //
302 static DIR *open_directory_secure(const char* dirname) {
303 // Open the directory using open() so that it can be verified
304 // to be secure by calling is_dirfd_secure(), opendir() and then check
305 // to see if they are the same file system object. This method does not
306 // introduce a window of opportunity for the directory to be attacked that
307 // calling opendir() and is_directory_secure() does.
308 int result;
309 DIR *dirp = NULL;
310 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result);
311 if (result == OS_ERR) {
312 // Directory doesn't exist or is a symlink, so there is nothing to cleanup.
313 if (PrintMiscellaneous && Verbose) {
314 if (errno == ELOOP) {
315 warning("directory %s is a symlink and is not secure\n", dirname);
316 } else {
317 warning("could not open directory %s: %s\n", dirname, os::strerror(errno));
318 }
319 }
320 return dirp;
321 }
322 int fd = result;
323
324 // Determine if the open directory is secure.
325 if (!is_dirfd_secure(fd)) {
326 // The directory is not a secure directory.
327 os::close(fd);
328 return dirp;
329 }
330
331 // Open the directory.
332 dirp = ::opendir(dirname);
333 if (dirp == NULL) {
334 // The directory doesn't exist, close fd and return.
335 os::close(fd);
336 return dirp;
337 }
338
339 // Check to make sure fd and dirp are referencing the same file system object.
340 if (!is_same_fsobject(fd, dirp->d_fd)) {
341 // The directory is not secure.
342 os::close(fd);
343 os::closedir(dirp);
344 dirp = NULL;
345 return dirp;
346 }
347
348 // Close initial open now that we know directory is secure
349 os::close(fd);
350
351 return dirp;
352 }
353
354 // NOTE: The code below uses fchdir(), open() and unlink() because
355 // fdopendir(), openat() and unlinkat() are not supported on all
356 // versions. Once the support for fdopendir(), openat() and unlinkat()
357 // is available on all supported versions the code can be changed
358 // to use these functions.
359
360 // Open the directory of the given path, validate it and set the
361 // current working directory to it.
362 // Return a DIR * of the open directory and the saved cwd fd.
363 //
364 static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) {
365
366 // Open the directory.
367 DIR* dirp = open_directory_secure(dirname);
368 if (dirp == NULL) {
369 // Directory doesn't exist or is insecure, so there is nothing to cleanup.
370 return dirp;
371 }
372 int fd = dirp->d_fd;
373
374 // Open a fd to the cwd and save it off.
375 int result;
376 RESTARTABLE(::open(".", O_RDONLY), result);
377 if (result == OS_ERR) {
378 *saved_cwd_fd = -1;
379 } else {
380 *saved_cwd_fd = result;
381 }
382
383 // Set the current directory to dirname by using the fd of the directory and
384 // handle errors, otherwise shared memory files will be created in cwd.
385 result = fchdir(fd);
386 if (result == OS_ERR) {
387 if (PrintMiscellaneous && Verbose) {
388 warning("could not change to directory %s", dirname);
389 }
390 if (*saved_cwd_fd != -1) {
391 ::close(*saved_cwd_fd);
392 *saved_cwd_fd = -1;
393 }
394 // Close the directory.
395 os::closedir(dirp);
396 return NULL;
397 } else {
398 return dirp;
399 }
400 }
401
402 // Close the directory and restore the current working directory.
403 //
404 static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) {
405
406 int result;
407 // If we have a saved cwd change back to it and close the fd.
408 if (saved_cwd_fd != -1) {
409 result = fchdir(saved_cwd_fd);
410 ::close(saved_cwd_fd);
411 }
412
413 // Close the directory.
414 os::closedir(dirp);
415 }
416
417 // Check if the given file descriptor is considered a secure.
418 //
419 static bool is_file_secure(int fd, const char *filename) {
420
421 int result;
422 struct stat statbuf;
423
424 // Determine if the file is secure.
425 RESTARTABLE(::fstat(fd, &statbuf), result);
426 if (result == OS_ERR) {
427 if (PrintMiscellaneous && Verbose) {
428 warning("fstat failed on %s: %s\n", filename, os::strerror(errno));
429 }
430 return false;
431 }
432 if (statbuf.st_nlink > 1) {
433 // A file with multiple links is not expected.
434 if (PrintMiscellaneous && Verbose) {
435 warning("file %s has multiple links\n", filename);
436 }
437 return false;
438 }
439 return true;
440 }
441
442 // return the user name for the given user id
443 //
444 // the caller is expected to free the allocated memory.
445 //
446 static char* get_user_name(uid_t uid) {
447
448 struct passwd pwent;
449
450 // determine the max pwbuf size from sysconf, and hardcode
451 // a default if this not available through sysconf.
452 //
453 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
454 if (bufsize == -1)
455 bufsize = 1024;
456
457 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
458
459 struct passwd* p = NULL;
460 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);
461
462 if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {
463 if (PrintMiscellaneous && Verbose) {
464 if (p == NULL) {
465 warning("Could not retrieve passwd entry: %s\n",
466 os::strerror(errno));
467 }
468 else {
469 warning("Could not determine user name: %s\n",
470 p->pw_name == NULL ? "pw_name = NULL" :
471 "pw_name zero length");
472 }
473 }
474 FREE_C_HEAP_ARRAY(char, pwbuf);
475 return NULL;
476 }
477
478 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal);
479 strcpy(user_name, p->pw_name);
480
481 FREE_C_HEAP_ARRAY(char, pwbuf);
482 return user_name;
483 }
484
485 // return the name of the user that owns the process identified by vmid.
486 //
487 // This method uses a slow directory search algorithm to find the backing
488 // store file for the specified vmid and returns the user name, as determined
489 // by the user name suffix of the hsperfdata_<username> directory name.
490 //
491 // the caller is expected to free the allocated memory.
492 //
493 static char* get_user_name_slow(int vmid, TRAPS) {
494
495 // short circuit the directory search if the process doesn't even exist.
496 if (kill(vmid, 0) == OS_ERR) {
497 if (errno == ESRCH) {
498 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
499 "Process not found");
500 }
501 else /* EPERM */ {
502 THROW_MSG_0(vmSymbols::java_io_IOException(), os::strerror(errno));
503 }
504 }
505
506 // directory search
507 char* oldest_user = NULL;
508 time_t oldest_ctime = 0;
509
510 const char* tmpdirname = os::get_temp_directory();
511
512 // open the temp directory
513 DIR* tmpdirp = os::opendir(tmpdirname);
514
515 if (tmpdirp == NULL) {
516 // Cannot open the directory to get the user name, return.
517 return NULL;
518 }
519
520 // for each entry in the directory that matches the pattern hsperfdata_*,
521 // open the directory and check if the file for the given vmid exists.
522 // The file with the expected name and the latest creation date is used
523 // to determine the user name for the process id.
524 //
525 struct dirent* dentry;
526 errno = 0;
527 while ((dentry = os::readdir(tmpdirp)) != NULL) {
528
529 // check if the directory entry is a hsperfdata file
530 if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) {
531 continue;
532 }
533
534 char* usrdir_name = NEW_C_HEAP_ARRAY(char,
535 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
536 strcpy(usrdir_name, tmpdirname);
537 strcat(usrdir_name, "/");
538 strcat(usrdir_name, dentry->d_name);
539
540 // open the user directory
541 DIR* subdirp = open_directory_secure(usrdir_name);
542
543 if (subdirp == NULL) {
544 FREE_C_HEAP_ARRAY(char, usrdir_name);
545 continue;
546 }
547
548 // Since we don't create the backing store files in directories
549 // pointed to by symbolic links, we also don't follow them when
550 // looking for the files. We check for a symbolic link after the
551 // call to opendir in order to eliminate a small window where the
552 // symlink can be exploited.
553 //
554 if (!is_directory_secure(usrdir_name)) {
555 FREE_C_HEAP_ARRAY(char, usrdir_name);
556 os::closedir(subdirp);
557 continue;
558 }
559
560 struct dirent* udentry;
561 errno = 0;
562 while ((udentry = os::readdir(subdirp)) != NULL) {
563
564 if (filename_to_pid(udentry->d_name) == vmid) {
565 struct stat statbuf;
566 int result;
567
568 char* filename = NEW_C_HEAP_ARRAY(char,
569 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
570
571 strcpy(filename, usrdir_name);
572 strcat(filename, "/");
573 strcat(filename, udentry->d_name);
574
575 // don't follow symbolic links for the file
576 RESTARTABLE(::lstat(filename, &statbuf), result);
577 if (result == OS_ERR) {
578 FREE_C_HEAP_ARRAY(char, filename);
579 continue;
580 }
581
582 // skip over files that are not regular files.
583 if (!S_ISREG(statbuf.st_mode)) {
584 FREE_C_HEAP_ARRAY(char, filename);
585 continue;
586 }
587
588 // compare and save filename with latest creation time
589 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
590
591 if (statbuf.st_ctime > oldest_ctime) {
592 char* user = strchr(dentry->d_name, '_') + 1;
593
594 FREE_C_HEAP_ARRAY(char, oldest_user);
595 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal);
596
597 strcpy(oldest_user, user);
598 oldest_ctime = statbuf.st_ctime;
599 }
600 }
601
602 FREE_C_HEAP_ARRAY(char, filename);
603 }
604 }
605 os::closedir(subdirp);
606 FREE_C_HEAP_ARRAY(char, usrdir_name);
607 }
608 os::closedir(tmpdirp);
609
610 return(oldest_user);
611 }
612
613 // return the name of the user that owns the JVM indicated by the given vmid.
614 //
615 static char* get_user_name(int vmid, TRAPS) {
616
617 char psinfo_name[PATH_MAX];
618 int result;
619
620 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid);
621
622 RESTARTABLE(::open(psinfo_name, O_RDONLY), result);
623
624 if (result != OS_ERR) {
625 int fd = result;
626
627 psinfo_t psinfo;
628 char* addr = (char*)&psinfo;
629
630 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) {
631
632 RESTARTABLE(::read(fd, addr, remaining), result);
633 if (result == OS_ERR) {
634 ::close(fd);
635 THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error");
636 } else {
637 remaining-=result;
638 addr+=result;
639 }
640 }
641
642 ::close(fd);
643
644 // get the user name for the effective user id of the process
645 char* user_name = get_user_name(psinfo.pr_euid);
646
647 return user_name;
648 }
649
650 if (result == OS_ERR && errno == EACCES) {
651
652 // In this case, the psinfo file for the process id existed,
653 // but we didn't have permission to access it.
654 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
655 os::strerror(errno));
656 }
657
658 // at this point, we don't know if the process id itself doesn't
659 // exist or if the psinfo file doesn't exit. If the psinfo file
660 // doesn't exist, then we are running on Solaris 2.5.1 or earlier.
661 // since the structured procfs and old procfs interfaces can't be
662 // mixed, we attempt to find the file through a directory search.
663
664 return get_user_name_slow(vmid, THREAD);
665 }
666
667 // return the file name of the backing store file for the named
668 // shared memory region for the given user name and vmid.
669 //
670 // the caller is expected to free the allocated memory.
671 //
672 static char* get_sharedmem_filename(const char* dirname, int vmid) {
673
674 // add 2 for the file separator and a NULL terminator.
675 size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
676
677 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
678 snprintf(name, nbytes, "%s/%d", dirname, vmid);
679
680 return name;
681 }
682
683
684 // remove file
685 //
686 // this method removes the file specified by the given path
687 //
688 static void remove_file(const char* path) {
689
690 int result;
691
692 // if the file is a directory, the following unlink will fail. since
693 // we don't expect to find directories in the user temp directory, we
694 // won't try to handle this situation. even if accidentially or
695 // maliciously planted, the directory's presence won't hurt anything.
696 //
697 RESTARTABLE(::unlink(path), result);
698 if (PrintMiscellaneous && Verbose && result == OS_ERR) {
699 if (errno != ENOENT) {
700 warning("Could not unlink shared memory backing"
701 " store file %s : %s\n", path, os::strerror(errno));
702 }
703 }
704 }
705
706
707 // cleanup stale shared memory resources
708 //
709 // This method attempts to remove all stale shared memory files in
710 // the named user temporary directory. It scans the named directory
711 // for files matching the pattern ^$[0-9]*$. For each file found, the
712 // process id is extracted from the file name and a test is run to
713 // determine if the process is alive. If the process is not alive,
714 // any stale file resources are removed.
715 //
716 static void cleanup_sharedmem_resources(const char* dirname) {
717
718 int saved_cwd_fd;
719 // open the directory
720 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
721 if (dirp == NULL) {
722 // directory doesn't exist or is insecure, so there is nothing to cleanup
723 return;
724 }
725
726 // for each entry in the directory that matches the expected file
727 // name pattern, determine if the file resources are stale and if
728 // so, remove the file resources. Note, instrumented HotSpot processes
729 // for this user may start and/or terminate during this search and
730 // remove or create new files in this directory. The behavior of this
731 // loop under these conditions is dependent upon the implementation of
732 // opendir/readdir.
733 //
734 struct dirent* entry;
735 errno = 0;
736 while ((entry = os::readdir(dirp)) != NULL) {
737
738 pid_t pid = filename_to_pid(entry->d_name);
739
740 if (pid == 0) {
741
742 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
743
744 // attempt to remove all unexpected files, except "." and ".."
745 unlink(entry->d_name);
746 }
747
748 errno = 0;
749 continue;
750 }
751
752 // we now have a file name that converts to a valid integer
753 // that could represent a process id . if this process id
754 // matches the current process id or the process is not running,
755 // then remove the stale file resources.
756 //
757 // process liveness is detected by sending signal number 0 to
758 // the process id (see kill(2)). if kill determines that the
759 // process does not exist, then the file resources are removed.
760 // if kill determines that that we don't have permission to
761 // signal the process, then the file resources are assumed to
762 // be stale and are removed because the resources for such a
763 // process should be in a different user specific directory.
764 //
765 if ((pid == os::current_process_id()) ||
766 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
767
768 unlink(entry->d_name);
769 }
770 errno = 0;
771 }
772
773 // close the directory and reset the current working directory
774 close_directory_secure_cwd(dirp, saved_cwd_fd);
775 }
776
777 // make the user specific temporary directory. Returns true if
778 // the directory exists and is secure upon return. Returns false
779 // if the directory exists but is either a symlink, is otherwise
780 // insecure, or if an error occurred.
781 //
782 static bool make_user_tmp_dir(const char* dirname) {
783
784 // create the directory with 0755 permissions. note that the directory
785 // will be owned by euid::egid, which may not be the same as uid::gid.
786 //
787 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
788 if (errno == EEXIST) {
789 // The directory already exists and was probably created by another
790 // JVM instance. However, this could also be the result of a
791 // deliberate symlink. Verify that the existing directory is safe.
792 //
793 if (!is_directory_secure(dirname)) {
794 // directory is not secure
795 if (PrintMiscellaneous && Verbose) {
796 warning("%s directory is insecure\n", dirname);
797 }
798 return false;
799 }
800 }
801 else {
802 // we encountered some other failure while attempting
803 // to create the directory
804 //
805 if (PrintMiscellaneous && Verbose) {
806 warning("could not create directory %s: %s\n",
807 dirname, os::strerror(errno));
808 }
809 return false;
810 }
811 }
812 return true;
813 }
814
815 // create the shared memory file resources
816 //
817 // This method creates the shared memory file with the given size
818 // This method also creates the user specific temporary directory, if
819 // it does not yet exist.
820 //
821 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
822
823 // make the user temporary directory
824 if (!make_user_tmp_dir(dirname)) {
825 // could not make/find the directory or the found directory
826 // was not secure
827 return -1;
828 }
829
830 int saved_cwd_fd;
831 // open the directory and set the current working directory to it
832 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
833 if (dirp == NULL) {
834 // Directory doesn't exist or is insecure, so cannot create shared
835 // memory file.
836 return -1;
837 }
838
839 // Open the filename in the current directory.
840 // Cannot use O_TRUNC here; truncation of an existing file has to happen
841 // after the is_file_secure() check below.
842 int result;
843 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result);
844 if (result == OS_ERR) {
845 if (PrintMiscellaneous && Verbose) {
846 if (errno == ELOOP) {
847 warning("file %s is a symlink and is not secure\n", filename);
848 } else {
849 warning("could not create file %s: %s\n", filename, os::strerror(errno));
850 }
851 }
852 // close the directory and reset the current working directory
853 close_directory_secure_cwd(dirp, saved_cwd_fd);
854
855 return -1;
856 }
857 // close the directory and reset the current working directory
858 close_directory_secure_cwd(dirp, saved_cwd_fd);
859
860 // save the file descriptor
861 int fd = result;
862
863 // check to see if the file is secure
864 if (!is_file_secure(fd, filename)) {
865 ::close(fd);
866 return -1;
867 }
868
869 // truncate the file to get rid of any existing data
870 RESTARTABLE(::ftruncate(fd, (off_t)0), result);
871 if (result == OS_ERR) {
872 if (PrintMiscellaneous && Verbose) {
873 warning("could not truncate shared memory file: %s\n", os::strerror(errno));
874 }
875 ::close(fd);
876 return -1;
877 }
878 // set the file size
879 RESTARTABLE(::ftruncate(fd, (off_t)size), result);
880 if (result == OS_ERR) {
881 if (PrintMiscellaneous && Verbose) {
882 warning("could not set shared memory file size: %s\n", os::strerror(errno));
883 }
884 ::close(fd);
885 return -1;
886 }
887
888 return fd;
889 }
890
891 // open the shared memory file for the given user and vmid. returns
892 // the file descriptor for the open file or -1 if the file could not
893 // be opened.
894 //
895 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
896
897 // open the file
898 int result;
899 RESTARTABLE(::open(filename, oflags), result);
900 if (result == OS_ERR) {
901 if (errno == ENOENT) {
902 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
903 "Process not found", OS_ERR);
904 }
905 else if (errno == EACCES) {
906 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
907 "Permission denied", OS_ERR);
908 }
909 else {
910 THROW_MSG_(vmSymbols::java_io_IOException(),
911 os::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, 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);
971 FREE_C_HEAP_ARRAY(char, dirname);
972
973 if (fd == -1) {
974 FREE_C_HEAP_ARRAY(char, filename);
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", os::strerror(errno));
986 }
987 remove_file(filename);
988 FREE_C_HEAP_ARRAY(char, filename);
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", os::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_io_IOException(),
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);
1119 if (luser != user) {
1120 FREE_C_HEAP_ARRAY(char, luser);
1121 }
1122 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1123 "Process not found");
1124 }
1125
1126 char* filename = get_sharedmem_filename(dirname, vmid);
1127
1128 // copy heap memory to resource memory. the open_sharedmem_file
1129 // method below need to use the filename, but could throw an
1130 // exception. using a resource array prevents the leak that
1131 // would otherwise occur.
1132 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
1133 strcpy(rfilename, filename);
1134
1135 // free the c heap resources that are no longer needed
1136 if (luser != user) FREE_C_HEAP_ARRAY(char, luser);
1137 FREE_C_HEAP_ARRAY(char, dirname);
1138 FREE_C_HEAP_ARRAY(char, filename);
1139
1140 // open the shared memory file for the give vmid
1141 fd = open_sharedmem_file(rfilename, file_flags, THREAD);
1142
1143 if (fd == OS_ERR) {
1144 return;
1145 }
1146
1147 if (HAS_PENDING_EXCEPTION) {
1148 ::close(fd);
1149 return;
1150 }
1151
1152 if (*sizep == 0) {
1153 size = sharedmem_filesize(fd, CHECK);
1154 } else {
1155 size = *sizep;
1156 }
1157
1158 assert(size > 0, "unexpected size <= 0");
1159
1160 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
1161
1162 result = ::close(fd);
1163 assert(result != OS_ERR, "could not close file");
1164
1165 if (mapAddress == MAP_FAILED) {
1166 if (PrintMiscellaneous && Verbose) {
1167 warning("mmap failed: %s\n", os::strerror(errno));
1168 }
1169 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
1170 "Could not map PerfMemory");
1171 }
1172
1173 // it does not go through os api, the operation has to record from here
1174 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress,
1175 size, CURRENT_PC, mtInternal);
1176
1177 *addr = mapAddress;
1178 *sizep = size;
1179
1180 log_debug(perf, memops)("mapped " SIZE_FORMAT " bytes for vmid %d at "
1181 INTPTR_FORMAT, size, vmid, (void*)mapAddress);
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 }