truffle: src/os/linux/vm/perfMemory

comparison src/os/linux/vm/perfMemory_linux.cpp @ 21816:60a992c821f8

8050807: Better performing performance data handling Reviewed-by: dcubed, dholmes, pnauman, ctornqvi, mschoene Contributed-by: gerald.thornbrugh@oracle.com

author	hseigel
date	Fri, 24 Oct 2014 15:02:37 -0400
parents	78bbf4d43a14
children	5ca2ea5eeff0

comparison

equal deleted inserted replaced

-:37179dcf830a
+:60a992c821f8
 // successful conversion, return the pid
 return pid;
 }
-// check if the given path is considered a secure directory for
+// 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) {
 RESTARTABLE(::lstat(path, &statbuf), result);
 if (result == OS_ERR) {
 return false;
 }
-// the path exists, now check it's mode
+// The path exists, see if it is secure.
-if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) {
+return is_statbuf_secure(&statbuf);
-// the path represents a link or some non-directory file type,
+}
-// which is not what we expected. declare it insecure.
-//
+// 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;
 }
-else {
-// we have an existing directory, check if the permissions are safe.
+// The path exists, now check its mode.
-//
+return is_statbuf_secure(&statbuf);
-if ((statbuf.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
+}
-// the directory is open for writing and could be subjected
-// to a symlnk attack. declare it insecure.
-//
+// Check to make sure fd1 and fd2 are referencing the same file system object.
-return false;
+//
-}
+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, dirfd(dirp))) {
+// 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 = dirfd(dirp);
+// 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;
 }
 char* oldest_user = NULL;
 time_t oldest_ctime = 0;
 const char* tmpdirname = os::get_temp_directory();
-DIR* tmpdirp = os::opendir(tmpdirname);
+// open the temp directory
+DIR* tmpdirp = open_directory_secure(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.
 strlen(tmpdirname) + strlen(dentry->d_name) + 2, mtInternal);
 strcpy(usrdir_name, tmpdirname);
 strcat(usrdir_name, "/");
 strcat(usrdir_name, dentry->d_name);
-DIR* subdirp = os::opendir(usrdir_name);
+// open the user directory
+DIR* subdirp = open_directory_secure(usrdir_name);
 if (subdirp == NULL) {
 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
 continue;
 }
 }
 }
 }
-// remove file
-//
-// this method removes the file with the given file name in the
-// named directory.
-//
-static void remove_file(const char* dirname, const char* filename) {
-size_t nbytes = strlen(dirname) + strlen(filename) + 2;
-char* path = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
-strcpy(path, dirname);
-strcat(path, "/");
-strcat(path, filename);
-remove_file(path);
-FREE_C_HEAP_ARRAY(char, path, mtInternal);
-}
 // 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
 // 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) {
-// open the user temp directory
+int saved_cwd_fd;
-DIR* dirp = os::opendir(dirname);
+// open the directory
+DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
 if (dirp == NULL) {
-// directory doesn't exist, so there is nothing to cleanup
+// directory doesn't exist or is insecure, so there is nothing to cleanup
-return;
-}
-if (!is_directory_secure(dirname)) {
-// the directory is not a secure directory
 return;
 }
 // for each entry in the directory that matches the expected file
 // name pattern, determine if the file resources are stale and if
 // 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 ".."
-remove_file(dirname, entry->d_name);
+unlink(entry->d_name);
 }
 errno = 0;
 continue;
 }
 // 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);
-remove_file(dirname, entry->d_name);
 }
 errno = 0;
 }
-os::closedir(dirp);
+// 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
 // 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);
-RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result);
 if (result == OS_ERR) {
 if (PrintMiscellaneous && Verbose) {
-warning("could not create file %s: %s\n", filename, strerror(errno));
+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));
 }
 else {
 THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR);
 }
 }
+int fd = result;
-return 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.
 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, filename, 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) {
 // 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;
+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;
+file_flags = O_RDWR | O_NOFOLLOW;
 #else
 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
 "Unsupported access mode");
 #endif
 }

Mercurial > hg > truffle

comparison src/os/linux/vm/perfMemory_linux.cpp @ 21816:60a992c821f8