/* * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "classfile/vmSymbols.hpp" #include "memory/allocation.inline.hpp" #include "memory/resourceArea.hpp" #include "oops/oop.inline.hpp" #include "os_solaris.inline.hpp" #include "runtime/handles.inline.hpp" #include "runtime/perfMemory.hpp" #include "services/memTracker.hpp" #include "utilities/exceptions.hpp" // put OS-includes here # include # include # include # include # include # include # include # include # include static char* backing_store_file_name = NULL; // name of the backing store // file, if successfully created. // Standard Memory Implementation Details // create the PerfData memory region in standard memory. // static char* create_standard_memory(size_t size) { // allocate an aligned chuck of memory char* mapAddress = os::reserve_memory(size); if (mapAddress == NULL) { return NULL; } // commit memory if (!os::commit_memory(mapAddress, size, !ExecMem)) { if (PrintMiscellaneous && Verbose) { warning("Could not commit PerfData memory\n"); } os::release_memory(mapAddress, size); return NULL; } return mapAddress; } // delete the PerfData memory region // static void delete_standard_memory(char* addr, size_t size) { // there are no persistent external resources to cleanup for standard // memory. since DestroyJavaVM does not support unloading of the JVM, // cleanup of the memory resource is not performed. The memory will be // reclaimed by the OS upon termination of the process. // return; } // save the specified memory region to the given file // // Note: this function might be called from signal handler (by os::abort()), // don't allocate heap memory. // static void save_memory_to_file(char* addr, size_t size) { const char* destfile = PerfMemory::get_perfdata_file_path(); assert(destfile[0] != '\0', "invalid PerfData file path"); int result; RESTARTABLE(::open(destfile, O_CREAT|O_WRONLY|O_TRUNC, S_IREAD|S_IWRITE), result);; if (result == OS_ERR) { if (PrintMiscellaneous && Verbose) { warning("Could not create Perfdata save file: %s: %s\n", destfile, strerror(errno)); } } else { int fd = result; for (size_t remaining = size; remaining > 0;) { RESTARTABLE(::write(fd, addr, remaining), result); if (result == OS_ERR) { if (PrintMiscellaneous && Verbose) { warning("Could not write Perfdata save file: %s: %s\n", destfile, strerror(errno)); } break; } remaining -= (size_t)result; addr += result; } result = ::close(fd); if (PrintMiscellaneous && Verbose) { if (result == OS_ERR) { warning("Could not close %s: %s\n", destfile, strerror(errno)); } } } FREE_C_HEAP_ARRAY(char, destfile, mtInternal); } // Shared Memory Implementation Details // Note: the solaris and linux shared memory implementation uses the mmap // interface with a backing store file to implement named shared memory. // Using the file system as the name space for shared memory allows a // common name space to be supported across a variety of platforms. It // also provides a name space that Java applications can deal with through // simple file apis. // // The solaris and linux implementations store the backing store file in // a user specific temporary directory located in the /tmp file system, // which is always a local file system and is sometimes a RAM based file // system. // return the user specific temporary directory name. // // the caller is expected to free the allocated memory. // static char* get_user_tmp_dir(const char* user) { const char* tmpdir = os::get_temp_directory(); const char* perfdir = PERFDATA_NAME; size_t nbytes = strlen(tmpdir) + strlen(perfdir) + strlen(user) + 3; char* dirname = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); // construct the path name to user specific tmp directory snprintf(dirname, nbytes, "%s/%s_%s", tmpdir, perfdir, user); return dirname; } // convert the given file name into a process id. if the file // does not meet the file naming constraints, return 0. // static pid_t filename_to_pid(const char* filename) { // a filename that doesn't begin with a digit is not a // candidate for conversion. // if (!isdigit(*filename)) { return 0; } // check if file name can be converted to an integer without // any leftover characters. // char* remainder = NULL; errno = 0; pid_t pid = (pid_t)strtol(filename, &remainder, 10); if (errno != 0) { return 0; } // check for left over characters. If any, then the filename is // not a candidate for conversion. // if (remainder != NULL && *remainder != '\0') { return 0; } // successful conversion, return the pid return pid; } // Check if the given statbuf is considered a secure directory for // the backing store files. Returns true if the directory is considered // a secure location. Returns false if the statbuf is a symbolic link or // if an error occurred. // static bool is_statbuf_secure(struct stat *statp) { if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) { // The path represents a link or some non-directory file type, // which is not what we expected. Declare it insecure. // return false; } // We have an existing directory, check if the permissions are safe. // if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) { // The directory is open for writing and could be subjected // to a symlink or a hard link attack. Declare it insecure. // return false; } // See if the uid of the directory matches the effective uid of the process. // if (statp->st_uid != geteuid()) { // The directory was not created by this user, declare it insecure. // return false; } return true; } // Check if the given path is considered a secure directory for // the backing store files. Returns true if the directory exists // and is considered a secure location. Returns false if the path // is a symbolic link or if an error occurred. // static bool is_directory_secure(const char* path) { struct stat statbuf; int result = 0; RESTARTABLE(::lstat(path, &statbuf), result); if (result == OS_ERR) { return false; } // The path exists, see if it is secure. return is_statbuf_secure(&statbuf); } // Check if the given directory file descriptor is considered a secure // directory for the backing store files. Returns true if the directory // exists and is considered a secure location. Returns false if the path // is a symbolic link or if an error occurred. // static bool is_dirfd_secure(int dir_fd) { struct stat statbuf; int result = 0; RESTARTABLE(::fstat(dir_fd, &statbuf), result); if (result == OS_ERR) { return false; } // The path exists, now check its mode. return is_statbuf_secure(&statbuf); } // Check to make sure fd1 and fd2 are referencing the same file system object. // static bool is_same_fsobject(int fd1, int fd2) { struct stat statbuf1; struct stat statbuf2; int result = 0; RESTARTABLE(::fstat(fd1, &statbuf1), result); if (result == OS_ERR) { return false; } RESTARTABLE(::fstat(fd2, &statbuf2), result); if (result == OS_ERR) { return false; } if ((statbuf1.st_ino == statbuf2.st_ino) && (statbuf1.st_dev == statbuf2.st_dev)) { return true; } else { return false; } } // Open the directory of the given path and validate it. // Return a DIR * of the open directory. // static DIR *open_directory_secure(const char* dirname) { // Open the directory using open() so that it can be verified // to be secure by calling is_dirfd_secure(), opendir() and then check // to see if they are the same file system object. This method does not // introduce a window of opportunity for the directory to be attacked that // calling opendir() and is_directory_secure() does. int result; DIR *dirp = NULL; RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result); if (result == OS_ERR) { // Directory doesn't exist or is a symlink, so there is nothing to cleanup. if (PrintMiscellaneous && Verbose) { if (errno == ELOOP) { warning("directory %s is a symlink and is not secure\n", dirname); } else { warning("could not open directory %s: %s\n", dirname, strerror(errno)); } } return dirp; } int fd = result; // Determine if the open directory is secure. if (!is_dirfd_secure(fd)) { // The directory is not a secure directory. os::close(fd); return dirp; } // Open the directory. dirp = ::opendir(dirname); if (dirp == NULL) { // The directory doesn't exist, close fd and return. os::close(fd); return dirp; } // Check to make sure fd and dirp are referencing the same file system object. if (!is_same_fsobject(fd, dirp->dd_fd)) { // The directory is not secure. os::close(fd); os::closedir(dirp); dirp = NULL; return dirp; } // Close initial open now that we know directory is secure os::close(fd); return dirp; } // NOTE: The code below uses fchdir(), open() and unlink() because // fdopendir(), openat() and unlinkat() are not supported on all // versions. Once the support for fdopendir(), openat() and unlinkat() // is available on all supported versions the code can be changed // to use these functions. // Open the directory of the given path, validate it and set the // current working directory to it. // Return a DIR * of the open directory and the saved cwd fd. // static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) { // Open the directory. DIR* dirp = open_directory_secure(dirname); if (dirp == NULL) { // Directory doesn't exist or is insecure, so there is nothing to cleanup. return dirp; } int fd = dirp->dd_fd; // Open a fd to the cwd and save it off. int result; RESTARTABLE(::open(".", O_RDONLY), result); if (result == OS_ERR) { *saved_cwd_fd = -1; } else { *saved_cwd_fd = result; } // Set the current directory to dirname by using the fd of the directory. result = fchdir(fd); return dirp; } // Close the directory and restore the current working directory. // static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) { int result; // If we have a saved cwd change back to it and close the fd. if (saved_cwd_fd != -1) { result = fchdir(saved_cwd_fd); ::close(saved_cwd_fd); } // Close the directory. os::closedir(dirp); } // Check if the given file descriptor is considered a secure. // static bool is_file_secure(int fd, const char *filename) { int result; struct stat statbuf; // Determine if the file is secure. RESTARTABLE(::fstat(fd, &statbuf), result); if (result == OS_ERR) { if (PrintMiscellaneous && Verbose) { warning("fstat failed on %s: %s\n", filename, strerror(errno)); } return false; } if (statbuf.st_nlink > 1) { // A file with multiple links is not expected. if (PrintMiscellaneous && Verbose) { warning("file %s has multiple links\n", filename); } return false; } return true; } // return the user name for the given user id // // the caller is expected to free the allocated memory. // static char* get_user_name(uid_t uid) { struct passwd pwent; // determine the max pwbuf size from sysconf, and hardcode // a default if this not available through sysconf. // long bufsize = sysconf(_SC_GETPW_R_SIZE_MAX); if (bufsize == -1) bufsize = 1024; char* pwbuf = NEW_C_HEAP_ARRAY(char, bufsize, mtInternal); #ifdef _GNU_SOURCE struct passwd* p = NULL; int result = getpwuid_r(uid, &pwent, pwbuf, (size_t)bufsize, &p); #else // _GNU_SOURCE struct passwd* p = getpwuid_r(uid, &pwent, pwbuf, (int)bufsize); #endif // _GNU_SOURCE if (p == NULL || p->pw_name == NULL || *(p->pw_name) == '\0') { if (PrintMiscellaneous && Verbose) { if (p == NULL) { warning("Could not retrieve passwd entry: %s\n", strerror(errno)); } else { warning("Could not determine user name: %s\n", p->pw_name == NULL ? "pw_name = NULL" : "pw_name zero length"); } } FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal); return NULL; } char* user_name = NEW_C_HEAP_ARRAY(char, strlen(p->pw_name) + 1, mtInternal); strcpy(user_name, p->pw_name); FREE_C_HEAP_ARRAY(char, pwbuf, mtInternal); return user_name; } // return the name of the user that owns the process identified by vmid. // // This method uses a slow directory search algorithm to find the backing // store file for the specified vmid and returns the user name, as determined // by the user name suffix of the hsperfdata_ directory name. // // the caller is expected to free the allocated memory. // static char* get_user_name_slow(int vmid, TRAPS) { // short circuit the directory search if the process doesn't even exist. if (kill(vmid, 0) == OS_ERR) { if (errno == ESRCH) { THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), "Process not found"); } else /* EPERM */ { THROW_MSG_0(vmSymbols::java_io_IOException(), strerror(errno)); } } // directory search char* oldest_user = NULL; time_t oldest_ctime = 0; const char* tmpdirname = os::get_temp_directory(); // open the temp directory DIR* tmpdirp = os::opendir(tmpdirname); if (tmpdirp == NULL) { // Cannot open the directory to get the user name, return. return NULL; } // for each entry in the directory that matches the pattern hsperfdata_*, // open the directory and check if the file for the given vmid exists. // The file with the expected name and the latest creation date is used // to determine the user name for the process id. // struct dirent* dentry; char* tdbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(tmpdirname), mtInternal); errno = 0; while ((dentry = os::readdir(tmpdirp, (struct dirent *)tdbuf)) != NULL) { // check if the directory entry is a hsperfdata file if (strncmp(dentry->d_name, PERFDATA_NAME, strlen(PERFDATA_NAME)) != 0) { continue; } char* usrdir_name = NEW_C_HEAP_ARRAY(char, strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal); strcpy(usrdir_name, tmpdirname); strcat(usrdir_name, "/"); strcat(usrdir_name, dentry->d_name); // open the user directory DIR* subdirp = open_directory_secure(usrdir_name); if (subdirp == NULL) { FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); continue; } // Since we don't create the backing store files in directories // pointed to by symbolic links, we also don't follow them when // looking for the files. We check for a symbolic link after the // call to opendir in order to eliminate a small window where the // symlink can be exploited. // if (!is_directory_secure(usrdir_name)) { FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); os::closedir(subdirp); continue; } struct dirent* udentry; char* udbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(usrdir_name), mtInternal); errno = 0; while ((udentry = os::readdir(subdirp, (struct dirent *)udbuf)) != NULL) { if (filename_to_pid(udentry->d_name) == vmid) { struct stat statbuf; int result; char* filename = NEW_C_HEAP_ARRAY(char, strlen(usrdir_name) + strlen(udentry->d_name) + 2, mtInternal); strcpy(filename, usrdir_name); strcat(filename, "/"); strcat(filename, udentry->d_name); // don't follow symbolic links for the file RESTARTABLE(::lstat(filename, &statbuf), result); if (result == OS_ERR) { FREE_C_HEAP_ARRAY(char, filename, mtInternal); continue; } // skip over files that are not regular files. if (!S_ISREG(statbuf.st_mode)) { FREE_C_HEAP_ARRAY(char, filename, mtInternal); continue; } // compare and save filename with latest creation time if (statbuf.st_size > 0 && statbuf.st_ctime > oldest_ctime) { if (statbuf.st_ctime > oldest_ctime) { char* user = strchr(dentry->d_name, '_') + 1; if (oldest_user != NULL) FREE_C_HEAP_ARRAY(char, oldest_user, mtInternal); oldest_user = NEW_C_HEAP_ARRAY(char, strlen(user)+1, mtInternal); strcpy(oldest_user, user); oldest_ctime = statbuf.st_ctime; } } FREE_C_HEAP_ARRAY(char, filename, mtInternal); } } os::closedir(subdirp); FREE_C_HEAP_ARRAY(char, udbuf, mtInternal); FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal); } os::closedir(tmpdirp); FREE_C_HEAP_ARRAY(char, tdbuf, mtInternal); return(oldest_user); } // return the name of the user that owns the JVM indicated by the given vmid. // static char* get_user_name(int vmid, TRAPS) { char psinfo_name[PATH_MAX]; int result; snprintf(psinfo_name, PATH_MAX, "/proc/%d/psinfo", vmid); RESTARTABLE(::open(psinfo_name, O_RDONLY), result); if (result != OS_ERR) { int fd = result; psinfo_t psinfo; char* addr = (char*)&psinfo; for (size_t remaining = sizeof(psinfo_t); remaining > 0;) { RESTARTABLE(::read(fd, addr, remaining), result); if (result == OS_ERR) { ::close(fd); THROW_MSG_0(vmSymbols::java_io_IOException(), "Read error"); } else { remaining-=result; addr+=result; } } ::close(fd); // get the user name for the effective user id of the process char* user_name = get_user_name(psinfo.pr_euid); return user_name; } if (result == OS_ERR && errno == EACCES) { // In this case, the psinfo file for the process id existed, // but we didn't have permission to access it. THROW_MSG_0(vmSymbols::java_lang_IllegalArgumentException(), strerror(errno)); } // at this point, we don't know if the process id itself doesn't // exist or if the psinfo file doesn't exit. If the psinfo file // doesn't exist, then we are running on Solaris 2.5.1 or earlier. // since the structured procfs and old procfs interfaces can't be // mixed, we attempt to find the file through a directory search. return get_user_name_slow(vmid, CHECK_NULL); } // return the file name of the backing store file for the named // shared memory region for the given user name and vmid. // // the caller is expected to free the allocated memory. // static char* get_sharedmem_filename(const char* dirname, int vmid) { // add 2 for the file separator and a NULL terminator. size_t nbytes = strlen(dirname) + UINT_CHARS + 2; char* name = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal); snprintf(name, nbytes, "%s/%d", dirname, vmid); return name; } // remove file // // this method removes the file specified by the given path // static void remove_file(const char* path) { int result; // if the file is a directory, the following unlink will fail. since // we don't expect to find directories in the user temp directory, we // won't try to handle this situation. even if accidentially or // maliciously planted, the directory's presence won't hurt anything. // RESTARTABLE(::unlink(path), result); if (PrintMiscellaneous && Verbose && result == OS_ERR) { if (errno != ENOENT) { warning("Could not unlink shared memory backing" " store file %s : %s\n", path, strerror(errno)); } } } // cleanup stale shared memory resources // // This method attempts to remove all stale shared memory files in // the named user temporary directory. It scans the named directory // for files matching the pattern ^$[0-9]*$. For each file found, the // process id is extracted from the file name and a test is run to // determine if the process is alive. If the process is not alive, // any stale file resources are removed. // static void cleanup_sharedmem_resources(const char* dirname) { int saved_cwd_fd; // open the directory DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); if (dirp == NULL) { // directory doesn't exist or is insecure, so there is nothing to cleanup return; } // for each entry in the directory that matches the expected file // name pattern, determine if the file resources are stale and if // so, remove the file resources. Note, instrumented HotSpot processes // for this user may start and/or terminate during this search and // remove or create new files in this directory. The behavior of this // loop under these conditions is dependent upon the implementation of // opendir/readdir. // struct dirent* entry; char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal); errno = 0; while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) { pid_t pid = filename_to_pid(entry->d_name); if (pid == 0) { if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) { // attempt to remove all unexpected files, except "." and ".." unlink(entry->d_name); } errno = 0; continue; } // we now have a file name that converts to a valid integer // that could represent a process id . if this process id // matches the current process id or the process is not running, // then remove the stale file resources. // // process liveness is detected by sending signal number 0 to // the process id (see kill(2)). if kill determines that the // process does not exist, then the file resources are removed. // if kill determines that that we don't have permission to // signal the process, then the file resources are assumed to // be stale and are removed because the resources for such a // process should be in a different user specific directory. // if ((pid == os::current_process_id()) || (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { unlink(entry->d_name); } errno = 0; } // close the directory and reset the current working directory close_directory_secure_cwd(dirp, saved_cwd_fd); FREE_C_HEAP_ARRAY(char, dbuf, mtInternal); } // make the user specific temporary directory. Returns true if // the directory exists and is secure upon return. Returns false // if the directory exists but is either a symlink, is otherwise // insecure, or if an error occurred. // static bool make_user_tmp_dir(const char* dirname) { // create the directory with 0755 permissions. note that the directory // will be owned by euid::egid, which may not be the same as uid::gid. // if (mkdir(dirname, S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) == OS_ERR) { if (errno == EEXIST) { // The directory already exists and was probably created by another // JVM instance. However, this could also be the result of a // deliberate symlink. Verify that the existing directory is safe. // if (!is_directory_secure(dirname)) { // directory is not secure if (PrintMiscellaneous && Verbose) { warning("%s directory is insecure\n", dirname); } return false; } } else { // we encountered some other failure while attempting // to create the directory // if (PrintMiscellaneous && Verbose) { warning("could not create directory %s: %s\n", dirname, strerror(errno)); } return false; } } return true; } // create the shared memory file resources // // This method creates the shared memory file with the given size // This method also creates the user specific temporary directory, if // it does not yet exist. // static int create_sharedmem_resources(const char* dirname, const char* filename, size_t size) { // make the user temporary directory if (!make_user_tmp_dir(dirname)) { // could not make/find the directory or the found directory // was not secure return -1; } int saved_cwd_fd; // open the directory and set the current working directory to it DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd); if (dirp == NULL) { // Directory doesn't exist or is insecure, so cannot create shared // memory file. return -1; } // Open the filename in the current directory. // Cannot use O_TRUNC here; truncation of an existing file has to happen // after the is_file_secure() check below. int result; RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result); if (result == OS_ERR) { if (PrintMiscellaneous && Verbose) { if (errno == ELOOP) { warning("file %s is a symlink and is not secure\n", filename); } else { warning("could not create file %s: %s\n", filename, strerror(errno)); } } // close the directory and reset the current working directory close_directory_secure_cwd(dirp, saved_cwd_fd); return -1; } // close the directory and reset the current working directory close_directory_secure_cwd(dirp, saved_cwd_fd); // save the file descriptor int fd = result; // check to see if the file is secure if (!is_file_secure(fd, filename)) { ::close(fd); return -1; } // truncate the file to get rid of any existing data RESTARTABLE(::ftruncate(fd, (off_t)0), result); if (result == OS_ERR) { if (PrintMiscellaneous && Verbose) { warning("could not truncate shared memory file: %s\n", strerror(errno)); } ::close(fd); return -1; } // set the file size RESTARTABLE(::ftruncate(fd, (off_t)size), result); if (result == OS_ERR) { if (PrintMiscellaneous && Verbose) { warning("could not set shared memory file size: %s\n", strerror(errno)); } ::close(fd); return -1; } return fd; } // open the shared memory file for the given user and vmid. returns // the file descriptor for the open file or -1 if the file could not // be opened. // static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { // open the file int result; RESTARTABLE(::open(filename, oflags), result); if (result == OS_ERR) { if (errno == ENOENT) { THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), "Process not found", OS_ERR); } else if (errno == EACCES) { THROW_MSG_(vmSymbols::java_lang_IllegalArgumentException(), "Permission denied", OS_ERR); } else { THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR); } } int fd = result; // check to see if the file is secure if (!is_file_secure(fd, filename)) { ::close(fd); return -1; } return fd; } // create a named shared memory region. returns the address of the // memory region on success or NULL on failure. A return value of // NULL will ultimately disable the shared memory feature. // // On Solaris and Linux, the name space for shared memory objects // is the file system name space. // // A monitoring application attaching to a JVM does not need to know // the file system name of the shared memory object. However, it may // be convenient for applications to discover the existence of newly // created and terminating JVMs by watching the file system name space // for files being created or removed. // static char* mmap_create_shared(size_t size) { int result; int fd; char* mapAddress; int vmid = os::current_process_id(); char* user_name = get_user_name(geteuid()); if (user_name == NULL) return NULL; char* dirname = get_user_tmp_dir(user_name); char* filename = get_sharedmem_filename(dirname, vmid); // get the short filename char* short_filename = strrchr(filename, '/'); if (short_filename == NULL) { short_filename = filename; } else { short_filename++; } // cleanup any stale shared memory files cleanup_sharedmem_resources(dirname); assert(((size > 0) && (size % os::vm_page_size() == 0)), "unexpected PerfMemory region size"); fd = create_sharedmem_resources(dirname, short_filename, size); FREE_C_HEAP_ARRAY(char, user_name, mtInternal); FREE_C_HEAP_ARRAY(char, dirname, mtInternal); if (fd == -1) { FREE_C_HEAP_ARRAY(char, filename, mtInternal); return NULL; } mapAddress = (char*)::mmap((char*)0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); result = ::close(fd); assert(result != OS_ERR, "could not close file"); if (mapAddress == MAP_FAILED) { if (PrintMiscellaneous && Verbose) { warning("mmap failed - %s\n", strerror(errno)); } remove_file(filename); FREE_C_HEAP_ARRAY(char, filename, mtInternal); return NULL; } // save the file name for use in delete_shared_memory() backing_store_file_name = filename; // clear the shared memory region (void)::memset((void*) mapAddress, 0, size); // it does not go through os api, the operation has to record from here MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal); return mapAddress; } // release a named shared memory region // static void unmap_shared(char* addr, size_t bytes) { os::release_memory(addr, bytes); } // create the PerfData memory region in shared memory. // static char* create_shared_memory(size_t size) { // create the shared memory region. return mmap_create_shared(size); } // delete the shared PerfData memory region // static void delete_shared_memory(char* addr, size_t size) { // cleanup the persistent shared memory resources. since DestroyJavaVM does // not support unloading of the JVM, unmapping of the memory resource is // not performed. The memory will be reclaimed by the OS upon termination of // the process. The backing store file is deleted from the file system. assert(!PerfDisableSharedMem, "shouldn't be here"); if (backing_store_file_name != NULL) { remove_file(backing_store_file_name); // Don't.. Free heap memory could deadlock os::abort() if it is called // from signal handler. OS will reclaim the heap memory. // FREE_C_HEAP_ARRAY(char, backing_store_file_name); backing_store_file_name = NULL; } } // return the size of the file for the given file descriptor // or 0 if it is not a valid size for a shared memory file // static size_t sharedmem_filesize(int fd, TRAPS) { struct stat statbuf; int result; RESTARTABLE(::fstat(fd, &statbuf), result); if (result == OS_ERR) { if (PrintMiscellaneous && Verbose) { warning("fstat failed: %s\n", strerror(errno)); } THROW_MSG_0(vmSymbols::java_io_IOException(), "Could not determine PerfMemory size"); } if ((statbuf.st_size == 0) || ((size_t)statbuf.st_size % os::vm_page_size() != 0)) { THROW_MSG_0(vmSymbols::java_lang_Exception(), "Invalid PerfMemory size"); } return (size_t)statbuf.st_size; } // attach to a named shared memory region. // static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemoryMode mode, char** addr, size_t* sizep, TRAPS) { char* mapAddress; int result; int fd; size_t size = 0; const char* luser = NULL; int mmap_prot; int file_flags; ResourceMark rm; // map the high level access mode to the appropriate permission // constructs for the file and the shared memory mapping. if (mode == PerfMemory::PERF_MODE_RO) { mmap_prot = PROT_READ; file_flags = O_RDONLY | O_NOFOLLOW; } else if (mode == PerfMemory::PERF_MODE_RW) { #ifdef LATER mmap_prot = PROT_READ | PROT_WRITE; file_flags = O_RDWR | O_NOFOLLOW; #else THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "Unsupported access mode"); #endif } else { THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "Illegal access mode"); } if (user == NULL || strlen(user) == 0) { luser = get_user_name(vmid, CHECK); } else { luser = user; } if (luser == NULL) { THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "Could not map vmid to user Name"); } char* dirname = get_user_tmp_dir(luser); // since we don't follow symbolic links when creating the backing // store file, we don't follow them when attaching either. // if (!is_directory_secure(dirname)) { FREE_C_HEAP_ARRAY(char, dirname, mtInternal); THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), "Process not found"); } char* filename = get_sharedmem_filename(dirname, vmid); // copy heap memory to resource memory. the open_sharedmem_file // method below need to use the filename, but could throw an // exception. using a resource array prevents the leak that // would otherwise occur. char* rfilename = NEW_RESOURCE_ARRAY(char, strlen(filename) + 1); strcpy(rfilename, filename); // free the c heap resources that are no longer needed if (luser != user) FREE_C_HEAP_ARRAY(char, luser, mtInternal); FREE_C_HEAP_ARRAY(char, dirname, mtInternal); FREE_C_HEAP_ARRAY(char, filename, mtInternal); // open the shared memory file for the give vmid fd = open_sharedmem_file(rfilename, file_flags, THREAD); if (fd == OS_ERR) { return; } if (HAS_PENDING_EXCEPTION) { ::close(fd); return; } if (*sizep == 0) { size = sharedmem_filesize(fd, CHECK); } else { size = *sizep; } assert(size > 0, "unexpected size <= 0"); mapAddress = (char*)::mmap((char*)0, size, mmap_prot, MAP_SHARED, fd, 0); result = ::close(fd); assert(result != OS_ERR, "could not close file"); if (mapAddress == MAP_FAILED) { if (PrintMiscellaneous && Verbose) { warning("mmap failed: %s\n", strerror(errno)); } THROW_MSG(vmSymbols::java_lang_OutOfMemoryError(), "Could not map PerfMemory"); } // it does not go through os api, the operation has to record from here MemTracker::record_virtual_memory_reserve_and_commit((address)mapAddress, size, CURRENT_PC, mtInternal); *addr = mapAddress; *sizep = size; if (PerfTraceMemOps) { tty->print("mapped " SIZE_FORMAT " bytes for vmid %d at " INTPTR_FORMAT "\n", size, vmid, (void*)mapAddress); } } // create the PerfData memory region // // This method creates the memory region used to store performance // data for the JVM. The memory may be created in standard or // shared memory. // void PerfMemory::create_memory_region(size_t size) { if (PerfDisableSharedMem) { // do not share the memory for the performance data. _start = create_standard_memory(size); } else { _start = create_shared_memory(size); if (_start == NULL) { // creation of the shared memory region failed, attempt // to create a contiguous, non-shared memory region instead. // if (PrintMiscellaneous && Verbose) { warning("Reverting to non-shared PerfMemory region.\n"); } PerfDisableSharedMem = true; _start = create_standard_memory(size); } } if (_start != NULL) _capacity = size; } // delete the PerfData memory region // // This method deletes the memory region used to store performance // data for the JVM. The memory region indicated by the // tuple will be inaccessible after a call to this method. // void PerfMemory::delete_memory_region() { assert((start() != NULL && capacity() > 0), "verify proper state"); // If user specifies PerfDataSaveFile, it will save the performance data // to the specified file name no matter whether PerfDataSaveToFile is specified // or not. In other word, -XX:PerfDataSaveFile=.. overrides flag // -XX:+PerfDataSaveToFile. if (PerfDataSaveToFile || PerfDataSaveFile != NULL) { save_memory_to_file(start(), capacity()); } if (PerfDisableSharedMem) { delete_standard_memory(start(), capacity()); } else { delete_shared_memory(start(), capacity()); } } // attach to the PerfData memory region for another JVM // // This method returns an tuple that points to // a memory buffer that is kept reasonably synchronized with // the PerfData memory region for the indicated JVM. This // buffer may be kept in synchronization via shared memory // or some other mechanism that keeps the buffer updated. // // If the JVM chooses not to support the attachability feature, // this method should throw an UnsupportedOperation exception. // // This implementation utilizes named shared memory to map // the indicated process's PerfData memory region into this JVMs // address space. // void PerfMemory::attach(const char* user, int vmid, PerfMemoryMode mode, char** addrp, size_t* sizep, TRAPS) { if (vmid == 0 || vmid == os::current_process_id()) { *addrp = start(); *sizep = capacity(); return; } mmap_attach_shared(user, vmid, mode, addrp, sizep, CHECK); } // detach from the PerfData memory region of another JVM // // This method detaches the PerfData memory region of another // JVM, specified as an tuple of a buffer // in this process's address space. This method may perform // arbitrary actions to accomplish the detachment. The memory // region specified by will be inaccessible after // a call to this method. // // If the JVM chooses not to support the attachability feature, // this method should throw an UnsupportedOperation exception. // // This implementation utilizes named shared memory to detach // the indicated process's PerfData memory region from this // process's address space. // void PerfMemory::detach(char* addr, size_t bytes, TRAPS) { assert(addr != 0, "address sanity check"); assert(bytes > 0, "capacity sanity check"); if (PerfMemory::contains(addr) || PerfMemory::contains(addr + bytes - 1)) { // prevent accidental detachment of this process's PerfMemory region return; } unmap_shared(addr, bytes); } char* PerfMemory::backing_store_filename() { return backing_store_file_name; }