1 /*
2 * Copyright (c) 2001, 2016, 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 <procfs.h>
45
46 /* For POSIX-compliant getpwuid_r on Solaris */
47 #define _POSIX_PTHREAD_SEMANTICS
48 #include <pwd.h>
49
50 static char* backing_store_file_name = NULL; // name of the backing store
51 // file, if successfully created.
52
53 // Standard Memory Implementation Details
54
55 // create the PerfData memory region in standard memory.
56 //
57 static char* create_standard_memory(size_t size) {
58
59 // allocate an aligned chuck of memory
60 char* mapAddress = os::reserve_memory(size);
61
62 if (mapAddress == NULL) {
63 return NULL;
64 }
65
66 // commit memory
67 if (!os::commit_memory(mapAddress, size, !ExecMem)) {
68 if (PrintMiscellaneous && Verbose) {
69 warning("Could not commit PerfData memory\n");
70 }
71 os::release_memory(mapAddress, size);
72 return NULL;
73 }
74
75 return mapAddress;
76 }
77
78 // delete the PerfData memory region
79 //
80 static void delete_standard_memory(char* addr, size_t size) {
81
82 // there are no persistent external resources to cleanup for standard
83 // memory. since DestroyJavaVM does not support unloading of the JVM,
84 // cleanup of the memory resource is not performed. The memory will be
85 // reclaimed by the OS upon termination of the process.
86 //
87 return;
88 }
89
90 // save the specified memory region to the given file
91 //
92 // Note: this function might be called from signal handler (by os::abort()),
93 // don't allocate heap memory.
94 //
95 static void save_memory_to_file(char* addr, size_t size) {
96
97 const char* destfile = PerfMemory::get_perfdata_file_path();
98 assert(destfile[0] != '\0', "invalid PerfData file path");
99
100 int result;
101
102 RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE),
103 result);;
104 if (result == OS_ERR) {
105 if (PrintMiscellaneous && Verbose) {
106 warning("Could not create Perfdata save file: %s: %s\n",
107 destfile, os::strerror(errno));
108 }
109 } else {
110
111 int fd = result;
112
113 for (size_t remaining = size; remaining > 0;) {
114
115 RESTARTABLE(::write(fd, addr, remaining), result);
116 if (result == OS_ERR) {
117 if (PrintMiscellaneous && Verbose) {
118 warning("Could not write Perfdata save file: %s: %s\n",
119 destfile, os::strerror(errno));
120 }
121 break;
122 }
123 remaining -= (size_t)result;
124 addr += result;
125 }
126
127 result = ::close(fd);
128 if (PrintMiscellaneous && Verbose) {
129 if (result == OS_ERR) {
130 warning("Could not close %s: %s\n", destfile, os::strerror(errno));
131 }
132 }
133 }
134 FREE_C_HEAP_ARRAY(char, destfile);
135 }
136
137
138 // Shared Memory Implementation Details
139
140 // Note: the solaris and linux shared memory implementation uses the mmap
141 // interface with a backing store file to implement named shared memory.
142 // Using the file system as the name space for shared memory allows a
143 // common name space to be supported across a variety of platforms. It
144 // also provides a name space that Java applications can deal with through
145 // simple file apis.
146 //
147 // The solaris and linux implementations store the backing store file in
148 // a user specific temporary directory located in the /tmp file system,
149 // which is always a local file system and is sometimes a RAM based file
150 // system.
151
152 // return the user specific temporary directory name.
153 //
154 // the caller is expected to free the allocated memory.
155 //
156 static char* get_user_tmp_dir(const char* user) {
157
158 const char* tmpdir = os::get_temp_directory();
159 const char* perfdir = PERFDATA_NAME;
160 size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3;
161 char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
162
163 // construct the path name to user specific tmp directory
164 snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user);
165
166 return dirname;
167 }
168
169 // convert the given file name into a process id. if the file
170 // does not meet the file naming constraints, return 0.
171 //
172 static pid_t filename_to_pid(const char* filename) {
173
174 // a filename that doesn't begin with a digit is not a
175 // candidate for conversion.
176 //
177 if (!isdigit(*filename)) {
178 return 0;
179 }
180
181 // check if file name can be converted to an integer without
182 // any leftover characters.
183 //
184 char* remainder = NULL;
185 errno = 0;
186 pid_t pid = (pid_t)strtol(filename, &remainder, 10);
187
188 if (errno != 0) {
189 return 0;
190 }
191
192 // check for left over characters. If any, then the filename is
193 // not a candidate for conversion.
194 //
195 if (remainder != NULL && *remainder != '\0') {
196 return 0;
197 }
198
199 // successful conversion, return the pid
200 return pid;
201 }
202
203
204 // Check if the given statbuf is considered a secure directory for
205 // the backing store files. Returns true if the directory is considered
206 // a secure location. Returns false if the statbuf is a symbolic link or
207 // if an error occurred.
208 //
209 static bool is_statbuf_secure(struct stat *statp) {
210 if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) {
211 // The path represents a link or some non-directory file type,
212 // which is not what we expected. Declare it insecure.
213 //
214 return false;
215 }
216 // We have an existing directory, check if the permissions are safe.
217 //
218 if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) {
219 // The directory is open for writing and could be subjected
220 // to a symlink or a hard link attack. Declare it insecure.
221 //
222 return false;
223 }
224 // If user is not root then see if the uid of the directory matches the effective uid of the process.
225 uid_t euid = geteuid();
226 if ((euid != 0) && (statp->st_uid != euid)) {
227 // The directory was not created by this user, declare it insecure.
228 //
229 return false;
230 }
231 return true;
232 }
233
234
235 // Check if the given path is considered a secure directory for
236 // the backing store files. Returns true if the directory exists
237 // and is considered a secure location. Returns false if the path
238 // is a symbolic link or if an error occurred.
239 //
240 static bool is_directory_secure(const char* path) {
241 struct stat statbuf;
242 int result = 0;
243
244 RESTARTABLE(::lstat(path, &statbuf), result);
245 if (result == OS_ERR) {
246 return false;
247 }
248
249 // The path exists, see if it is secure.
250 return is_statbuf_secure(&statbuf);
251 }
252
253
254 // Check if the given directory file descriptor is considered a secure
255 // directory for the backing store files. Returns true if the directory
256 // exists and is considered a secure location. Returns false if the path
257 // is a symbolic link or if an error occurred.
258 //
259 static bool is_dirfd_secure(int dir_fd) {
260 struct stat statbuf;
261 int result = 0;
262
263 RESTARTABLE(::fstat(dir_fd, &statbuf), result);
264 if (result == OS_ERR) {
265 return false;
266 }
267
268 // The path exists, now check its mode.
269 return is_statbuf_secure(&statbuf);
270 }
271
272
273 // Check to make sure fd1 and fd2 are referencing the same file system object.
274 //
275 static bool is_same_fsobject(int fd1, int fd2) {
276 struct stat statbuf1;
277 struct stat statbuf2;
278 int result = 0;
279
280 RESTARTABLE(::fstat(fd1, &statbuf1), result);
281 if (result == OS_ERR) {
282 return false;
283 }
284 RESTARTABLE(::fstat(fd2, &statbuf2), result);
285 if (result == OS_ERR) {
286 return false;
287 }
288
289 if ((statbuf1.st_ino == statbuf2.st_ino) &&
290 (statbuf1.st_dev == statbuf2.st_dev)) {
291 return true;
292 } else {
293 return false;
294 }
295 }
296
297
298 // Open the directory of the given path and validate it.
299 // Return a DIR * of the open directory.
300 //
301 static DIR *open_directory_secure(const char* dirname) {
302 // Open the directory using open() so that it can be verified
303 // to be secure by calling is_dirfd_secure(), opendir() and then check
304 // to see if they are the same file system object. This method does not
305 // introduce a window of opportunity for the directory to be attacked that
306 // calling opendir() and is_directory_secure() does.
307 int result;
308 DIR *dirp = NULL;
309 RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result);
310 if (result == OS_ERR) {
311 // Directory doesn't exist or is a symlink, so there is nothing to cleanup.
312 if (PrintMiscellaneous && Verbose) {
313 if (errno == ELOOP) {
314 warning("directory %s is a symlink and is not secure\n", dirname);
315 } else {
316 warning("could not open directory %s: %s\n", dirname, os::strerror(errno));
317 }
318 }
319 return dirp;
320 }
321 int fd = result;
322
323 // Determine if the open directory is secure.
324 if (!is_dirfd_secure(fd)) {
325 // The directory is not a secure directory.
326 os::close(fd);
327 return dirp;
328 }
329
330 // Open the directory.
331 dirp = ::opendir(dirname);
332 if (dirp == NULL) {
333 // The directory doesn't exist, close fd and return.
334 os::close(fd);
335 return dirp;
336 }
337
338 // Check to make sure fd and dirp are referencing the same file system object.
339 if (!is_same_fsobject(fd, dirp->d_fd)) {
340 // The directory is not secure.
341 os::close(fd);
342 os::closedir(dirp);
343 dirp = NULL;
344 return dirp;
345 }
346
347 // Close initial open now that we know directory is secure
348 os::close(fd);
349
350 return dirp;
351 }
352
353 // NOTE: The code below uses fchdir(), open() and unlink() because
354 // fdopendir(), openat() and unlinkat() are not supported on all
355 // versions. Once the support for fdopendir(), openat() and unlinkat()
356 // is available on all supported versions the code can be changed
357 // to use these functions.
358
359 // Open the directory of the given path, validate it and set the
360 // current working directory to it.
361 // Return a DIR * of the open directory and the saved cwd fd.
362 //
363 static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) {
364
365 // Open the directory.
366 DIR* dirp = open_directory_secure(dirname);
367 if (dirp == NULL) {
368 // Directory doesn't exist or is insecure, so there is nothing to cleanup.
369 return dirp;
370 }
371 int fd = dirp->d_fd;
372
373 // Open a fd to the cwd and save it off.
374 int result;
375 RESTARTABLE(::open(".", O_RDONLY), result);
376 if (result == OS_ERR) {
377 *saved_cwd_fd = -1;
378 } else {
379 *saved_cwd_fd = result;
380 }
381
382 // Set the current directory to dirname by using the fd of the directory and
383 // handle errors, otherwise shared memory files will be created in cwd.
384 result = fchdir(fd);
385 if (result == OS_ERR) {
386 if (PrintMiscellaneous && Verbose) {
387 warning("could not change to directory %s", dirname);
388 }
389 if (*saved_cwd_fd != -1) {
390 ::close(*saved_cwd_fd);
391 *saved_cwd_fd = -1;
392 }
393 // Close the directory.
394 os::closedir(dirp);
395 return NULL;
396 } else {
397 return dirp;
398 }
399 }
400
401 // Close the directory and restore the current working directory.
402 //
403 static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) {
404
405 int result;
406 // If we have a saved cwd change back to it and close the fd.
407 if (saved_cwd_fd != -1) {
408 result = fchdir(saved_cwd_fd);
409 ::close(saved_cwd_fd);
410 }
411
412 // Close the directory.
413 os::closedir(dirp);
414 }
415
416 // Check if the given file descriptor is considered a secure.
417 //
418 static bool is_file_secure(int fd, const char *filename) {
419
420 int result;
421 struct stat statbuf;
422
423 // Determine if the file is secure.
424 RESTARTABLE(::fstat(fd, &statbuf), result);
425 if (result == OS_ERR) {
426 if (PrintMiscellaneous && Verbose) {
427 warning("fstat failed on %s: %s\n", filename, os::strerror(errno));
428 }
429 return false;
430 }
431 if (statbuf.st_nlink > 1) {
432 // A file with multiple links is not expected.
433 if (PrintMiscellaneous && Verbose) {
434 warning("file %s has multiple links\n", filename);
435 }
436 return false;
437 }
438 return true;
439 }
440
441 // return the user name for the given user id
442 //
443 // the caller is expected to free the allocated memory.
444 //
445 static char* get_user_name(uid_t uid) {
446
447 struct passwd pwent;
448
449 // determine the max pwbuf size from sysconf, and hardcode
450 // a default if this not available through sysconf.
451 //
452 long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
453 if (bufsize == -1)
454 bufsize = 1024;
455
456 char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal);
457
458 struct passwd* p = NULL;
459 int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p);
460
461 if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') {
462 if (PrintMiscellaneous && Verbose) {
463 if (p == NULL) {
464 warning("Could not retrieve passwd entry: %s\n",
465 os::strerror(errno));
466 }
467 else {
468 warning("Could not determine user name: %s\n",
469 p->pw_name == NULL ? "pw_name = NULL" :
470 "pw_name zero length");
471 }
472 }
473 FREE_C_HEAP_ARRAY(char, pwbuf);
474 return NULL;
475 }
476
477 char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal);
478 strcpy(user_name, p->pw_name);
479
480 FREE_C_HEAP_ARRAY(char, pwbuf);
481 return user_name;
482 }
483
484 // return the name of the user that owns the process identified by vmid.
485 //
486 // This method uses a slow directory search algorithm to find the backing
487 // store file for the specified vmid and returns the user name, as determined
488 // by the user name suffix of the hsperfdata_<username> directory name.
489 //
490 // the caller is expected to free the allocated memory.
491 //
492 static char* get_user_name_slow(int vmid, TRAPS) {
493
494 // short circuit the directory search if the process doesn't even exist.
495 if (kill(vmid, 0) == OS_ERR) {
496 if (errno == ESRCH) {
497 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
498 "Process not found");
499 }
500 else /* EPERM */ {
501 THROW_MSG_0(vmSymbols::java_io_IOException(), os::strerror(errno));
502 }
503 }
504
505 // directory search
506 char* oldest_user = NULL;
507 time_t oldest_ctime = 0;
508
509 const char* tmpdirname = os::get_temp_directory();
510
511 // open the temp directory
512 DIR* tmpdirp = os::opendir(tmpdirname);
513
514 if (tmpdirp == NULL) {
515 // Cannot open the directory to get the user name, return.
516 return NULL;
517 }
518
519 // for each entry in the directory that matches the pattern hsperfdata_*,
520 // open the directory and check if the file for the given vmid exists.
521 // The file with the expected name and the latest creation date is used
522 // to determine the user name for the process id.
523 //
524 struct dirent* dentry;
525 char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal);
526 errno = 0;
527 while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != 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 char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal);
562 errno = 0;
563 while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) {
564
565 if (filename_to_pid(udentry->d_name) == vmid) {
566 struct stat statbuf;
567 int result;
568
569 char* filename = NEW_C_HEAP_ARRAY(char,
570 strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal);
571
572 strcpy(filename, usrdir_name);
573 strcat(filename, "/");
574 strcat(filename, udentry->d_name);
575
576 // don't follow symbolic links for the file
577 RESTARTABLE(::lstat(filename, &statbuf), result);
578 if (result == OS_ERR) {
579 FREE_C_HEAP_ARRAY(char, filename);
580 continue;
581 }
582
583 // skip over files that are not regular files.
584 if (!S_ISREG(statbuf.st_mode)) {
585 FREE_C_HEAP_ARRAY(char, filename);
586 continue;
587 }
588
589 // compare and save filename with latest creation time
590 if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) {
591
592 if (statbuf.st_ctime > oldest_ctime) {
593 char* user = strchr(dentry->d_name, '_') + 1;
594
595 if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user);
596 oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal);
597
598 strcpy(oldest_user, user);
599 oldest_ctime = statbuf.st_ctime;
600 }
601 }
602
603 FREE_C_HEAP_ARRAY(char, filename);
604 }
605 }
606 os::closedir(subdirp);
607 FREE_C_HEAP_ARRAY(char, udbuf);
608 FREE_C_HEAP_ARRAY(char, usrdir_name);
609 }
610 os::closedir(tmpdirp);
611 FREE_C_HEAP_ARRAY(char, tdbuf);
612
613 return(oldest_user);
614 }
615
616 // return the name of the user that owns the JVM indicated by the given vmid.
617 //
618 static char* get_user_name(int vmid, TRAPS) {
619
620 char psinfo_name[PATH_MAX];
621 int result;
622
623 snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid);
624
625 RESTARTABLE(::open(psinfo_name, O_RDONLY), result);
626
627 if (result != OS_ERR) {
628 int fd = result;
629
630 psinfo_t psinfo;
631 char* addr = (char*)&psinfo;
632
633 for (size_t remaining = sizeof(psinfo_t); remaining > 0;) {
634
635 RESTARTABLE(::read(fd, addr, remaining), result);
636 if (result == OS_ERR) {
637 ::close(fd);
638 THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error");
639 } else {
640 remaining-=result;
641 addr+=result;
642 }
643 }
644
645 ::close(fd);
646
647 // get the user name for the effective user id of the process
648 char* user_name = get_user_name(psinfo.pr_euid);
649
650 return user_name;
651 }
652
653 if (result == OS_ERR && errno == EACCES) {
654
655 // In this case, the psinfo file for the process id existed,
656 // but we didn't have permission to access it.
657 THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(),
658 os::strerror(errno));
659 }
660
661 // at this point, we don't know if the process id itself doesn't
662 // exist or if the psinfo file doesn't exit. If the psinfo file
663 // doesn't exist, then we are running on Solaris 2.5.1 or earlier.
664 // since the structured procfs and old procfs interfaces can't be
665 // mixed, we attempt to find the file through a directory search.
666
667 return get_user_name_slow(vmid, THREAD);
668 }
669
670 // return the file name of the backing store file for the named
671 // shared memory region for the given user name and vmid.
672 //
673 // the caller is expected to free the allocated memory.
674 //
675 static char* get_sharedmem_filename(const char* dirname, int vmid) {
676
677 // add 2 for the file separator and a NULL terminator.
678 size_t nbytes = strlen(dirname) + UINT_CHARS + 2;
679
680 char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
681 snprintf(name, nbytes, "%s/%d", dirname, vmid);
682
683 return name;
684 }
685
686
687 // remove file
688 //
689 // this method removes the file specified by the given path
690 //
691 static void remove_file(const char* path) {
692
693 int result;
694
695 // if the file is a directory, the following unlink will fail. since
696 // we don't expect to find directories in the user temp directory, we
697 // won't try to handle this situation. even if accidentially or
698 // maliciously planted, the directory's presence won't hurt anything.
699 //
700 RESTARTABLE(::unlink(path), result);
701 if (PrintMiscellaneous && Verbose && result == OS_ERR) {
702 if (errno != ENOENT) {
703 warning("Could not unlink shared memory backing"
704 " store file %s : %s\n", path, os::strerror(errno));
705 }
706 }
707 }
708
709
710 // cleanup stale shared memory resources
711 //
712 // This method attempts to remove all stale shared memory files in
713 // the named user temporary directory. It scans the named directory
714 // for files matching the pattern ^$[0-9]*$. For each file found, the
715 // process id is extracted from the file name and a test is run to
716 // determine if the process is alive. If the process is not alive,
717 // any stale file resources are removed.
718 //
719 static void cleanup_sharedmem_resources(const char* dirname) {
720
721 int saved_cwd_fd;
722 // open the directory
723 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
724 if (dirp == NULL) {
725 // directory doesn't exist or is insecure, so there is nothing to cleanup
726 return;
727 }
728
729 // for each entry in the directory that matches the expected file
730 // name pattern, determine if the file resources are stale and if
731 // so, remove the file resources. Note, instrumented HotSpot processes
732 // for this user may start and/or terminate during this search and
733 // remove or create new files in this directory. The behavior of this
734 // loop under these conditions is dependent upon the implementation of
735 // opendir/readdir.
736 //
737 struct dirent* entry;
738 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
739
740 errno = 0;
741 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
742
743 pid_t pid = filename_to_pid(entry->d_name);
744
745 if (pid == 0) {
746
747 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
748
749 // attempt to remove all unexpected files, except "." and ".."
750 unlink(entry->d_name);
751 }
752
753 errno = 0;
754 continue;
755 }
756
757 // we now have a file name that converts to a valid integer
758 // that could represent a process id . if this process id
759 // matches the current process id or the process is not running,
760 // then remove the stale file resources.
761 //
762 // process liveness is detected by sending signal number 0 to
763 // the process id (see kill(2)). if kill determines that the
764 // process does not exist, then the file resources are removed.
765 // if kill determines that that we don't have permission to
766 // signal the process, then the file resources are assumed to
767 // be stale and are removed because the resources for such a
768 // process should be in a different user specific directory.
769 //
770 if ((pid == os::current_process_id()) ||
771 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
772
773 unlink(entry->d_name);
774 }
775 errno = 0;
776 }
777
778 // close the directory and reset the current working directory
779 close_directory_secure_cwd(dirp, saved_cwd_fd);
780
781 FREE_C_HEAP_ARRAY(char, dbuf);
782 }
783
784 // make the user specific temporary directory. Returns true if
785 // the directory exists and is secure upon return. Returns false
786 // if the directory exists but is either a symlink, is otherwise
787 // insecure, or if an error occurred.
788 //
789 static bool make_user_tmp_dir(const char* dirname) {
790
791 // create the directory with 0755 permissions. note that the directory
792 // will be owned by euid::egid, which may not be the same as uid::gid.
793 //
794 if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) {
795 if (errno == EEXIST) {
796 // The directory already exists and was probably created by another
797 // JVM instance. However, this could also be the result of a
798 // deliberate symlink. Verify that the existing directory is safe.
799 //
800 if (!is_directory_secure(dirname)) {
801 // directory is not secure
802 if (PrintMiscellaneous && Verbose) {
803 warning("%s directory is insecure\n", dirname);
804 }
805 return false;
806 }
807 }
808 else {
809 // we encountered some other failure while attempting
810 // to create the directory
811 //
812 if (PrintMiscellaneous && Verbose) {
813 warning("could not create directory %s: %s\n",
814 dirname, os::strerror(errno));
815 }
816 return false;
817 }
818 }
819 return true;
820 }
821
822 // create the shared memory file resources
823 //
824 // This method creates the shared memory file with the given size
825 // This method also creates the user specific temporary directory, if
826 // it does not yet exist.
827 //
828 static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) {
829
830 // make the user temporary directory
831 if (!make_user_tmp_dir(dirname)) {
832 // could not make/find the directory or the found directory
833 // was not secure
834 return -1;
835 }
836
837 int saved_cwd_fd;
838 // open the directory and set the current working directory to it
839 DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
840 if (dirp == NULL) {
841 // Directory doesn't exist or is insecure, so cannot create shared
842 // memory file.
843 return -1;
844 }
845
846 // Open the filename in the current directory.
847 // Cannot use O_TRUNC here; truncation of an existing file has to happen
848 // after the is_file_secure() check below.
849 int result;
850 RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result);
851 if (result == OS_ERR) {
852 if (PrintMiscellaneous && Verbose) {
853 if (errno == ELOOP) {
854 warning("file %s is a symlink and is not secure\n", filename);
855 } else {
856 warning("could not create file %s: %s\n", filename, os::strerror(errno));
857 }
858 }
859 // close the directory and reset the current working directory
860 close_directory_secure_cwd(dirp, saved_cwd_fd);
861
862 return -1;
863 }
864 // close the directory and reset the current working directory
865 close_directory_secure_cwd(dirp, saved_cwd_fd);
866
867 // save the file descriptor
868 int fd = result;
869
870 // check to see if the file is secure
871 if (!is_file_secure(fd, filename)) {
872 ::close(fd);
873 return -1;
874 }
875
876 // truncate the file to get rid of any existing data
877 RESTARTABLE(::ftruncate(fd, (off_t)0), result);
878 if (result == OS_ERR) {
879 if (PrintMiscellaneous && Verbose) {
880 warning("could not truncate shared memory file: %s\n", os::strerror(errno));
881 }
882 ::close(fd);
883 return -1;
884 }
885 // set the file size
886 RESTARTABLE(::ftruncate(fd, (off_t)size), result);
887 if (result == OS_ERR) {
888 if (PrintMiscellaneous && Verbose) {
889 warning("could not set shared memory file size: %s\n", os::strerror(errno));
890 }
891 ::close(fd);
892 return -1;
893 }
894
895 return fd;
896 }
897
898 // open the shared memory file for the given user and vmid. returns
899 // the file descriptor for the open file or -1 if the file could not
900 // be opened.
901 //
902 static int open_sharedmem_file(const char* filename, int oflags, TRAPS) {
903
904 // open the file
905 int result;
906 RESTARTABLE(::open(filename, oflags), result);
907 if (result == OS_ERR) {
908 if (errno == ENOENT) {
909 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
910 "Process not found", OS_ERR);
911 }
912 else if (errno == EACCES) {
913 THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(),
914 "Permission denied", OS_ERR);
915 }
916 else {
917 THROW_MSG_(vmSymbols::java_io_IOException(), os::strerror(errno), OS_ERR);
918 }
919 }
920 int fd = result;
921
922 // check to see if the file is secure
923 if (!is_file_secure(fd, filename)) {
924 ::close(fd);
925 return -1;
926 }
927
928 return fd;
929 }
930
931 // create a named shared memory region. returns the address of the
932 // memory region on success or NULL on failure. A return value of
933 // NULL will ultimately disable the shared memory feature.
934 //
935 // On Solaris and Linux, the name space for shared memory objects
936 // is the file system name space.
937 //
938 // A monitoring application attaching to a JVM does not need to know
939 // the file system name of the shared memory object. However, it may
940 // be convenient for applications to discover the existence of newly
941 // created and terminating JVMs by watching the file system name space
942 // for files being created or removed.
943 //
944 static char* mmap_create_shared(size_t size) {
945
946 int result;
947 int fd;
948 char* mapAddress;
949
950 int vmid = os::current_process_id();
951
952 char* user_name = get_user_name(geteuid());
953
954 if (user_name == NULL)
955 return NULL;
956
957 char* dirname = get_user_tmp_dir(user_name);
958 char* filename = get_sharedmem_filename(dirname, vmid);
959
960 // get the short filename
961 char* short_filename = strrchr(filename, '/');
962 if (short_filename == NULL) {
963 short_filename = filename;
964 } else {
965 short_filename++;
966 }
967
968 // cleanup any stale shared memory files
969 cleanup_sharedmem_resources(dirname);
970
971 assert(((size > 0) && (size % os::vm_page_size() == 0)),
972 "unexpected PerfMemory region size");
973
974 fd = create_sharedmem_resources(dirname, short_filename, size);
975
976 FREE_C_HEAP_ARRAY(char, user_name);
977 FREE_C_HEAP_ARRAY(char, dirname);
978
979 if (fd == -1) {
980 FREE_C_HEAP_ARRAY(char, filename);
981 return NULL;
982 }
983
984 mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
985
986 result = ::close(fd);
987 assert(result != OS_ERR, "could not close file");
988
989 if (mapAddress == MAP_FAILED) {
990 if (PrintMiscellaneous && Verbose) {
991 warning("mmap failed - %s\n", os::strerror(errno));
992 }
993 remove_file(filename);
994 FREE_C_HEAP_ARRAY(char, filename);
995 return NULL;
996 }
997
998 // save the file name for use in delete_shared_memory()
999 backing_store_file_name = filename;
1000
1001 // clear the shared memory region
1002 (void)::memset((void*) mapAddress, 0, size);
1003
1004 // it does not go through os api, the operation has to record from here
1005 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress,
1006 size, CURRENT_PC, mtInternal);
1007
1008 return mapAddress;
1009 }
1010
1011 // release a named shared memory region
1012 //
1013 static void unmap_shared(char* addr, size_t bytes) {
1014 os::release_memory(addr, bytes);
1015 }
1016
1017 // create the PerfData memory region in shared memory.
1018 //
1019 static char* create_shared_memory(size_t size) {
1020
1021 // create the shared memory region.
1022 return mmap_create_shared(size);
1023 }
1024
1025 // delete the shared PerfData memory region
1026 //
1027 static void delete_shared_memory(char* addr, size_t size) {
1028
1029 // cleanup the persistent shared memory resources. since DestroyJavaVM does
1030 // not support unloading of the JVM, unmapping of the memory resource is
1031 // not performed. The memory will be reclaimed by the OS upon termination of
1032 // the process. The backing store file is deleted from the file system.
1033
1034 assert(!PerfDisableSharedMem, "shouldn't be here");
1035
1036 if (backing_store_file_name != NULL) {
1037 remove_file(backing_store_file_name);
1038 // Don't.. Free heap memory could deadlock os::abort() if it is called
1039 // from signal handler. OS will reclaim the heap memory.
1040 // FREE_C_HEAP_ARRAY(char, backing_store_file_name);
1041 backing_store_file_name = NULL;
1042 }
1043 }
1044
1045 // return the size of the file for the given file descriptor
1046 // or 0 if it is not a valid size for a shared memory file
1047 //
1048 static size_t sharedmem_filesize(int fd, TRAPS) {
1049
1050 struct stat statbuf;
1051 int result;
1052
1053 RESTARTABLE(::fstat(fd, &statbuf), result);
1054 if (result == OS_ERR) {
1055 if (PrintMiscellaneous && Verbose) {
1056 warning("fstat failed: %s\n", os::strerror(errno));
1057 }
1058 THROW_MSG_0(vmSymbols::java_io_IOException(),
1059 "Could not determine PerfMemory size");
1060 }
1061
1062 if ((statbuf.st_size == 0) ||
1063 ((size_t)statbuf.st_size % os::vm_page_size() != 0)) {
1064 THROW_MSG_0(vmSymbols::java_lang_Exception(),
1065 "Invalid PerfMemory size");
1066 }
1067
1068 return (size_t)statbuf.st_size;
1069 }
1070
1071 // attach to a named shared memory region.
1072 //
1073 static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) {
1074
1075 char* mapAddress;
1076 int result;
1077 int fd;
1078 size_t size = 0;
1079 const char* luser = NULL;
1080
1081 int mmap_prot;
1082 int file_flags;
1083
1084 ResourceMark rm;
1085
1086 // map the high level access mode to the appropriate permission
1087 // constructs for the file and the shared memory mapping.
1088 if (mode == PerfMemory::PERF_MODE_RO) {
1089 mmap_prot = PROT_READ;
1090 file_flags = O_RDONLY | O_NOFOLLOW;
1091 }
1092 else if (mode == PerfMemory::PERF_MODE_RW) {
1093 #ifdef LATER
1094 mmap_prot = PROT_READ | PROT_WRITE;
1095 file_flags = O_RDWR | O_NOFOLLOW;
1096 #else
1097 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1098 "Unsupported access mode");
1099 #endif
1100 }
1101 else {
1102 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1103 "Illegal access mode");
1104 }
1105
1106 if (user == NULL || strlen(user) == 0) {
1107 luser = get_user_name(vmid, CHECK);
1108 }
1109 else {
1110 luser = user;
1111 }
1112
1113 if (luser == NULL) {
1114 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1115 "Could not map vmid to user Name");
1116 }
1117
1118 char* dirname = get_user_tmp_dir(luser);
1119
1120 // since we don't follow symbolic links when creating the backing
1121 // store file, we don't follow them when attaching either.
1122 //
1123 if (!is_directory_secure(dirname)) {
1124 FREE_C_HEAP_ARRAY(char, dirname);
1125 if (luser != user) {
1126 FREE_C_HEAP_ARRAY(char, luser);
1127 }
1128 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1129 "Process not found");
1130 }
1131
1132 char* filename = get_sharedmem_filename(dirname, vmid);
1133
1134 // copy heap memory to resource memory. the open_sharedmem_file
1135 // method below need to use the filename, but could throw an
1136 // exception. using a resource array prevents the leak that
1137 // would otherwise occur.
1138 char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1);
1139 strcpy(rfilename, filename);
1140
1141 // free the c heap resources that are no longer needed
1142 if (luser != user) FREE_C_HEAP_ARRAY(char, luser);
1143 FREE_C_HEAP_ARRAY(char, dirname);
1144 FREE_C_HEAP_ARRAY(char, filename);
1145
1146 // open the shared memory file for the give vmid
1147 fd = open_sharedmem_file(rfilename, file_flags, THREAD);
1148
1149 if (fd == OS_ERR) {
1150 return;
1151 }
1152
1153 if (HAS_PENDING_EXCEPTION) {
1154 ::close(fd);
1155 return;
1156 }
1157
1158 if (*sizep == 0) {
1159 size = sharedmem_filesize(fd, CHECK);
1160 } else {
1161 size = *sizep;
1162 }
1163
1164 assert(size > 0, "unexpected size <= 0");
1165
1166 mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0);
1167
1168 result = ::close(fd);
1169 assert(result != OS_ERR, "could not close file");
1170
1171 if (mapAddress == MAP_FAILED) {
1172 if (PrintMiscellaneous && Verbose) {
1173 warning("mmap failed: %s\n", os::strerror(errno));
1174 }
1175 THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(),
1176 "Could not map PerfMemory");
1177 }
1178
1179 // it does not go through os api, the operation has to record from here
1180 MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress,
1181 size, CURRENT_PC, mtInternal);
1182
1183 *addr = mapAddress;
1184 *sizep = size;
1185
1186 if (PerfTraceMemOps) {
1187 tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at "
1188 INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress);
1189 }
1190 }
1191
1192
1193
1194
1195 // create the PerfData memory region
1196 //
1197 // This method creates the memory region used to store performance
1198 // data for the JVM. The memory may be created in standard or
1199 // shared memory.
1200 //
1201 void PerfMemory::create_memory_region(size_t size) {
1202
1203 if (PerfDisableSharedMem) {
1204 // do not share the memory for the performance data.
1205 _start = create_standard_memory(size);
1206 }
1207 else {
1208 _start = create_shared_memory(size);
1209 if (_start == NULL) {
1210
1211 // creation of the shared memory region failed, attempt
1212 // to create a contiguous, non-shared memory region instead.
1213 //
1214 if (PrintMiscellaneous && Verbose) {
1215 warning("Reverting to non-shared PerfMemory region.\n");
1216 }
1217 PerfDisableSharedMem = true;
1218 _start = create_standard_memory(size);
1219 }
1220 }
1221
1222 if (_start != NULL) _capacity = size;
1223
1224 }
1225
1226 // delete the PerfData memory region
1227 //
1228 // This method deletes the memory region used to store performance
1229 // data for the JVM. The memory region indicated by the <address, size>
1230 // tuple will be inaccessible after a call to this method.
1231 //
1232 void PerfMemory::delete_memory_region() {
1233
1234 assert((start() != NULL && capacity() > 0), "verify proper state");
1235
1236 // If user specifies PerfDataSaveFile, it will save the performance data
1237 // to the specified file name no matter whether PerfDataSaveToFile is specified
1238 // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag
1239 // -XX:+PerfDataSaveToFile.
1240 if (PerfDataSaveToFile || PerfDataSaveFile != NULL) {
1241 save_memory_to_file(start(), capacity());
1242 }
1243
1244 if (PerfDisableSharedMem) {
1245 delete_standard_memory(start(), capacity());
1246 }
1247 else {
1248 delete_shared_memory(start(), capacity());
1249 }
1250 }
1251
1252 // attach to the PerfData memory region for another JVM
1253 //
1254 // This method returns an <address, size> tuple that points to
1255 // a memory buffer that is kept reasonably synchronized with
1256 // the PerfData memory region for the indicated JVM. This
1257 // buffer may be kept in synchronization via shared memory
1258 // or some other mechanism that keeps the buffer updated.
1259 //
1260 // If the JVM chooses not to support the attachability feature,
1261 // this method should throw an UnsupportedOperation exception.
1262 //
1263 // This implementation utilizes named shared memory to map
1264 // the indicated process's PerfData memory region into this JVMs
1265 // address space.
1266 //
1267 void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) {
1268
1269 if (vmid == 0 || vmid == os::current_process_id()) {
1270 *addrp = start();
1271 *sizep = capacity();
1272 return;
1273 }
1274
1275 mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK);
1276 }
1277
1278 // detach from the PerfData memory region of another JVM
1279 //
1280 // This method detaches the PerfData memory region of another
1281 // JVM, specified as an <address, size> tuple of a buffer
1282 // in this process's address space. This method may perform
1283 // arbitrary actions to accomplish the detachment. The memory
1284 // region specified by <address, size> will be inaccessible after
1285 // a call to this method.
1286 //
1287 // If the JVM chooses not to support the attachability feature,
1288 // this method should throw an UnsupportedOperation exception.
1289 //
1290 // This implementation utilizes named shared memory to detach
1291 // the indicated process's PerfData memory region from this
1292 // process's address space.
1293 //
1294 void PerfMemory::detach(char* addr, size_t bytes, TRAPS) {
1295
1296 assert(addr != 0, "address sanity check");
1297 assert(bytes > 0, "capacity sanity check");
1298
1299 if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) {
1300 // prevent accidental detachment of this process's PerfMemory region
1301 return;
1302 }
1303
1304 unmap_shared(addr, bytes);
1305 }