From 2162f3c4307d3951867050670fba02d760de4ce3 Mon Sep 17 00:00:00 2001 From: gthornbr Date: Mon, 17 Nov 2014 15:51:46 -0500 Subject: [PATCH] 8050807: Better performing performance data handling Reviewed-by: dcubed, pnauman, ctornqvi, dholmes, mschoene Contributed-by: gerald.thornbrugh@oracle.com --- src/os/bsd/vm/perfMemory_bsd.cpp | 343 ++++++++++++++++++----- src/os/linux/vm/perfMemory_linux.cpp | 330 ++++++++++++++++++---- src/os/solaris/vm/perfMemory_solaris.cpp | 331 ++++++++++++++++++---- src/share/vm/utilities/vmError.cpp | 4 +- 4 files changed, 829 insertions(+), 179 deletions(-) diff --git a/src/os/bsd/vm/perfMemory_bsd.cpp b/src/os/bsd/vm/perfMemory_bsd.cpp index 2737fe38c..5ee992ec0 100644 --- a/src/os/bsd/vm/perfMemory_bsd.cpp +++ b/src/os/bsd/vm/perfMemory_bsd.cpp @@ -197,7 +197,38 @@ static pid_t filename_to_pid(const char* filename) { } -// 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. @@ -211,26 +242,184 @@ static bool is_directory_secure(const char* path) { return false; } - // the path exists, now check it's mode - if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) { - // the path represents a link or some non-directory file type, - // which is not what we expected. declare it insecure. - // + // 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; } - else { - // we have an existing directory, check if the permissions are safe. - // - 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. - // - 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; } - return true; + 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; +} // return the user name for the given user id // @@ -317,9 +506,11 @@ static char* get_user_name_slow(int vmid, TRAPS) { 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; } @@ -344,25 +535,14 @@ static char* get_user_name_slow(int vmid, TRAPS) { 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; } - // 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; @@ -465,26 +645,6 @@ static void remove_file(const char* path) { } -// 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 @@ -496,16 +656,11 @@ static void remove_file(const char* dirname, const char* filename) { // static void cleanup_sharedmem_resources(const char* dirname) { - // open the user temp directory - DIR* dirp = os::opendir(dirname); - + 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, so there is nothing to cleanup - return; - } - - if (!is_directory_secure(dirname)) { - // the directory is not a secure directory + // directory doesn't exist or is insecure, so there is nothing to cleanup return; } @@ -519,6 +674,7 @@ static void cleanup_sharedmem_resources(const char* dirname) { // 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) { @@ -529,7 +685,7 @@ static void cleanup_sharedmem_resources(const char* dirname) { 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; @@ -552,11 +708,14 @@ static void cleanup_sharedmem_resources(const char* dirname) { if ((pid == os::current_process_id()) || (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { - remove_file(dirname, entry->d_name); + unlink(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); } @@ -613,19 +772,54 @@ static int create_sharedmem_resources(const char* dirname, const char* filename, return -1; } - int result; + 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; + } - RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result); + // 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) { - 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) { @@ -683,8 +877,15 @@ static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 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 @@ -716,13 +917,21 @@ static char* mmap_create_shared(size_t size) { 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); @@ -837,12 +1046,12 @@ static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemor // 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"); diff --git a/src/os/linux/vm/perfMemory_linux.cpp b/src/os/linux/vm/perfMemory_linux.cpp index 2eef5da69..9beb1113e 100644 --- a/src/os/linux/vm/perfMemory_linux.cpp +++ b/src/os/linux/vm/perfMemory_linux.cpp @@ -197,7 +197,38 @@ static pid_t filename_to_pid(const char* filename) { } -// 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. @@ -211,22 +242,180 @@ static bool is_directory_secure(const char* path) { return false; } - // the path exists, now check it's mode - if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) { - // the path represents a link or some non-directory file type, - // which is not what we expected. declare it insecure. - // + // 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; } - else { - // we have an existing directory, check if the permissions are safe. - // - 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. - // - 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) { + 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; } @@ -317,9 +506,11 @@ static char* get_user_name_slow(int vmid, TRAPS) { 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; } @@ -344,7 +535,8 @@ static char* get_user_name_slow(int vmid, TRAPS) { 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); @@ -465,26 +657,6 @@ static void remove_file(const char* path) { } -// 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 @@ -496,16 +668,11 @@ static void remove_file(const char* dirname, const char* filename) { // static void cleanup_sharedmem_resources(const char* dirname) { - // open the user temp directory - DIR* dirp = os::opendir(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, so there is nothing to cleanup - return; - } - - if (!is_directory_secure(dirname)) { - // the directory is not a secure directory + // directory doesn't exist or is insecure, so there is nothing to cleanup return; } @@ -519,6 +686,7 @@ static void cleanup_sharedmem_resources(const char* dirname) { // 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) { @@ -527,9 +695,8 @@ static void cleanup_sharedmem_resources(const char* dirname) { 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; @@ -551,12 +718,14 @@ static void cleanup_sharedmem_resources(const char* dirname) { // if ((pid == os::current_process_id()) || (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { - - remove_file(dirname, entry->d_name); + unlink(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); } @@ -613,19 +782,54 @@ static int create_sharedmem_resources(const char* dirname, const char* filename, return -1; } - int result; + 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; + } - RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result); + // 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) { - 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) { @@ -683,8 +887,15 @@ static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 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 @@ -715,6 +926,13 @@ static char* mmap_create_shared(size_t size) { 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); @@ -722,7 +940,7 @@ static char* mmap_create_shared(size_t size) { 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); @@ -837,12 +1055,12 @@ static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemor // 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"); diff --git a/src/os/solaris/vm/perfMemory_solaris.cpp b/src/os/solaris/vm/perfMemory_solaris.cpp index 2d279af0c..996b6d889 100644 --- a/src/os/solaris/vm/perfMemory_solaris.cpp +++ b/src/os/solaris/vm/perfMemory_solaris.cpp @@ -199,7 +199,38 @@ static pid_t filename_to_pid(const char* filename) { } -// 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. @@ -213,26 +244,184 @@ static bool is_directory_secure(const char* path) { return false; } - // the path exists, now check it's mode - if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) { - // the path represents a link or some non-directory file type, - // which is not what we expected. declare it insecure. - // + // 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; } - else { - // we have an existing directory, check if the permissions are safe. - // - 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. - // - 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; } - return true; + 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 // @@ -308,9 +497,11 @@ static char* get_user_name_slow(int vmid, TRAPS) { 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; } @@ -335,7 +526,8 @@ static char* get_user_name_slow(int vmid, TRAPS) { 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); @@ -504,26 +696,6 @@ static void remove_file(const char* path) { } -// 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 @@ -535,16 +707,11 @@ static void remove_file(const char* dirname, const char* filename) { // static void cleanup_sharedmem_resources(const char* dirname) { - // open the user temp directory - DIR* dirp = os::opendir(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, so there is nothing to cleanup - return; - } - - if (!is_directory_secure(dirname)) { - // the directory is not a secure directory + // directory doesn't exist or is insecure, so there is nothing to cleanup return; } @@ -558,6 +725,7 @@ static void cleanup_sharedmem_resources(const char* dirname) { // 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) { @@ -568,7 +736,7 @@ static void cleanup_sharedmem_resources(const char* dirname) { 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; @@ -591,11 +759,14 @@ static void cleanup_sharedmem_resources(const char* dirname) { if ((pid == os::current_process_id()) || (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) { - remove_file(dirname, entry->d_name); + unlink(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); } @@ -652,19 +823,54 @@ static int create_sharedmem_resources(const char* dirname, const char* filename, return -1; } - int result; + 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; + } - RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result); + // 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) { - 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) { @@ -700,8 +906,15 @@ static int open_sharedmem_file(const char* filename, int oflags, TRAPS) { 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 result; + return fd; } // create a named shared memory region. returns the address of the @@ -733,13 +946,21 @@ static char* mmap_create_shared(size_t size) { 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); @@ -855,12 +1076,12 @@ static void mmap_attach_shared(const char* user, int vmid, PerfMemory::PerfMemor // 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"); diff --git a/src/share/vm/utilities/vmError.cpp b/src/share/vm/utilities/vmError.cpp index 0375207b0..e9abf2858 100644 --- a/src/share/vm/utilities/vmError.cpp +++ b/src/share/vm/utilities/vmError.cpp @@ -22,6 +22,7 @@ * */ +#include #include "precompiled.hpp" #include "compiler/compileBroker.hpp" #include "gc_interface/collectedHeap.hpp" @@ -841,7 +842,8 @@ fdStream VMError::log; // error log used by VMError::report_and_die() static int expand_and_open(const char* pattern, char* buf, size_t buflen, size_t pos) { int fd = -1; if (Arguments::copy_expand_pid(pattern, strlen(pattern), &buf[pos], buflen - pos)) { - fd = open(buf, O_RDWR | O_CREAT | O_TRUNC, 0666); + // the O_EXCL flag will cause the open to fail if the file exists + fd = open(buf, O_RDWR | O_CREAT | O_EXCL, 0666); } return fd; } -- GitLab