1.1 --- a/src/os/linux/vm/perfMemory_linux.cpp Mon Nov 24 09:18:13 2014 -0800
1.2 +++ b/src/os/linux/vm/perfMemory_linux.cpp Mon Nov 17 15:51:46 2014 -0500
1.3 @@ -197,7 +197,38 @@
1.4 }
1.5
1.6
1.7 -// check if the given path is considered a secure directory for
1.8 +// Check if the given statbuf is considered a secure directory for
1.9 +// the backing store files. Returns true if the directory is considered
1.10 +// a secure location. Returns false if the statbuf is a symbolic link or
1.11 +// if an error occurred.
1.12 +//
1.13 +static bool is_statbuf_secure(struct stat *statp) {
1.14 + if (S_ISLNK(statp->st_mode) || !S_ISDIR(statp->st_mode)) {
1.15 + // The path represents a link or some non-directory file type,
1.16 + // which is not what we expected. Declare it insecure.
1.17 + //
1.18 + return false;
1.19 + }
1.20 + // We have an existing directory, check if the permissions are safe.
1.21 + //
1.22 + if ((statp->st_mode & (S_IWGRP|S_IWOTH)) != 0) {
1.23 + // The directory is open for writing and could be subjected
1.24 + // to a symlink or a hard link attack. Declare it insecure.
1.25 + //
1.26 + return false;
1.27 + }
1.28 + // See if the uid of the directory matches the effective uid of the process.
1.29 + //
1.30 + if (statp->st_uid != geteuid()) {
1.31 + // The directory was not created by this user, declare it insecure.
1.32 + //
1.33 + return false;
1.34 + }
1.35 + return true;
1.36 +}
1.37 +
1.38 +
1.39 +// Check if the given path is considered a secure directory for
1.40 // the backing store files. Returns true if the directory exists
1.41 // and is considered a secure location. Returns false if the path
1.42 // is a symbolic link or if an error occurred.
1.43 @@ -211,22 +242,180 @@
1.44 return false;
1.45 }
1.46
1.47 - // the path exists, now check it's mode
1.48 - if (S_ISLNK(statbuf.st_mode) || !S_ISDIR(statbuf.st_mode)) {
1.49 - // the path represents a link or some non-directory file type,
1.50 - // which is not what we expected. declare it insecure.
1.51 - //
1.52 + // The path exists, see if it is secure.
1.53 + return is_statbuf_secure(&statbuf);
1.54 +}
1.55 +
1.56 +
1.57 +// Check if the given directory file descriptor is considered a secure
1.58 +// directory for the backing store files. Returns true if the directory
1.59 +// exists and is considered a secure location. Returns false if the path
1.60 +// is a symbolic link or if an error occurred.
1.61 +//
1.62 +static bool is_dirfd_secure(int dir_fd) {
1.63 + struct stat statbuf;
1.64 + int result = 0;
1.65 +
1.66 + RESTARTABLE(::fstat(dir_fd, &statbuf), result);
1.67 + if (result == OS_ERR) {
1.68 return false;
1.69 }
1.70 - else {
1.71 - // we have an existing directory, check if the permissions are safe.
1.72 - //
1.73 - if ((statbuf.st_mode & (S_IWGRP|S_IWOTH)) != 0) {
1.74 - // the directory is open for writing and could be subjected
1.75 - // to a symlnk attack. declare it insecure.
1.76 - //
1.77 - return false;
1.78 +
1.79 + // The path exists, now check its mode.
1.80 + return is_statbuf_secure(&statbuf);
1.81 +}
1.82 +
1.83 +
1.84 +// Check to make sure fd1 and fd2 are referencing the same file system object.
1.85 +//
1.86 +static bool is_same_fsobject(int fd1, int fd2) {
1.87 + struct stat statbuf1;
1.88 + struct stat statbuf2;
1.89 + int result = 0;
1.90 +
1.91 + RESTARTABLE(::fstat(fd1, &statbuf1), result);
1.92 + if (result == OS_ERR) {
1.93 + return false;
1.94 + }
1.95 + RESTARTABLE(::fstat(fd2, &statbuf2), result);
1.96 + if (result == OS_ERR) {
1.97 + return false;
1.98 + }
1.99 +
1.100 + if ((statbuf1.st_ino == statbuf2.st_ino) &&
1.101 + (statbuf1.st_dev == statbuf2.st_dev)) {
1.102 + return true;
1.103 + } else {
1.104 + return false;
1.105 + }
1.106 +}
1.107 +
1.108 +
1.109 +// Open the directory of the given path and validate it.
1.110 +// Return a DIR * of the open directory.
1.111 +//
1.112 +static DIR *open_directory_secure(const char* dirname) {
1.113 + // Open the directory using open() so that it can be verified
1.114 + // to be secure by calling is_dirfd_secure(), opendir() and then check
1.115 + // to see if they are the same file system object. This method does not
1.116 + // introduce a window of opportunity for the directory to be attacked that
1.117 + // calling opendir() and is_directory_secure() does.
1.118 + int result;
1.119 + DIR *dirp = NULL;
1.120 + RESTARTABLE(::open(dirname, O_RDONLY|O_NOFOLLOW), result);
1.121 + if (result == OS_ERR) {
1.122 + if (PrintMiscellaneous && Verbose) {
1.123 + if (errno == ELOOP) {
1.124 + warning("directory %s is a symlink and is not secure\n", dirname);
1.125 + } else {
1.126 + warning("could not open directory %s: %s\n", dirname, strerror(errno));
1.127 + }
1.128 }
1.129 + return dirp;
1.130 + }
1.131 + int fd = result;
1.132 +
1.133 + // Determine if the open directory is secure.
1.134 + if (!is_dirfd_secure(fd)) {
1.135 + // The directory is not a secure directory.
1.136 + os::close(fd);
1.137 + return dirp;
1.138 + }
1.139 +
1.140 + // Open the directory.
1.141 + dirp = ::opendir(dirname);
1.142 + if (dirp == NULL) {
1.143 + // The directory doesn't exist, close fd and return.
1.144 + os::close(fd);
1.145 + return dirp;
1.146 + }
1.147 +
1.148 + // Check to make sure fd and dirp are referencing the same file system object.
1.149 + if (!is_same_fsobject(fd, dirfd(dirp))) {
1.150 + // The directory is not secure.
1.151 + os::close(fd);
1.152 + os::closedir(dirp);
1.153 + dirp = NULL;
1.154 + return dirp;
1.155 + }
1.156 +
1.157 + // Close initial open now that we know directory is secure
1.158 + os::close(fd);
1.159 +
1.160 + return dirp;
1.161 +}
1.162 +
1.163 +// NOTE: The code below uses fchdir(), open() and unlink() because
1.164 +// fdopendir(), openat() and unlinkat() are not supported on all
1.165 +// versions. Once the support for fdopendir(), openat() and unlinkat()
1.166 +// is available on all supported versions the code can be changed
1.167 +// to use these functions.
1.168 +
1.169 +// Open the directory of the given path, validate it and set the
1.170 +// current working directory to it.
1.171 +// Return a DIR * of the open directory and the saved cwd fd.
1.172 +//
1.173 +static DIR *open_directory_secure_cwd(const char* dirname, int *saved_cwd_fd) {
1.174 +
1.175 + // Open the directory.
1.176 + DIR* dirp = open_directory_secure(dirname);
1.177 + if (dirp == NULL) {
1.178 + // Directory doesn't exist or is insecure, so there is nothing to cleanup.
1.179 + return dirp;
1.180 + }
1.181 + int fd = dirfd(dirp);
1.182 +
1.183 + // Open a fd to the cwd and save it off.
1.184 + int result;
1.185 + RESTARTABLE(::open(".", O_RDONLY), result);
1.186 + if (result == OS_ERR) {
1.187 + *saved_cwd_fd = -1;
1.188 + } else {
1.189 + *saved_cwd_fd = result;
1.190 + }
1.191 +
1.192 + // Set the current directory to dirname by using the fd of the directory.
1.193 + result = fchdir(fd);
1.194 +
1.195 + return dirp;
1.196 +}
1.197 +
1.198 +// Close the directory and restore the current working directory.
1.199 +//
1.200 +static void close_directory_secure_cwd(DIR* dirp, int saved_cwd_fd) {
1.201 +
1.202 + int result;
1.203 + // If we have a saved cwd change back to it and close the fd.
1.204 + if (saved_cwd_fd != -1) {
1.205 + result = fchdir(saved_cwd_fd);
1.206 + ::close(saved_cwd_fd);
1.207 + }
1.208 +
1.209 + // Close the directory.
1.210 + os::closedir(dirp);
1.211 +}
1.212 +
1.213 +// Check if the given file descriptor is considered a secure.
1.214 +//
1.215 +static bool is_file_secure(int fd, const char *filename) {
1.216 +
1.217 + int result;
1.218 + struct stat statbuf;
1.219 +
1.220 + // Determine if the file is secure.
1.221 + RESTARTABLE(::fstat(fd, &statbuf), result);
1.222 + if (result == OS_ERR) {
1.223 + if (PrintMiscellaneous && Verbose) {
1.224 + warning("fstat failed on %s: %s\n", filename, strerror(errno));
1.225 + }
1.226 + return false;
1.227 + }
1.228 + if (statbuf.st_nlink > 1) {
1.229 + // A file with multiple links is not expected.
1.230 + if (PrintMiscellaneous && Verbose) {
1.231 + warning("file %s has multiple links\n", filename);
1.232 + }
1.233 + return false;
1.234 }
1.235 return true;
1.236 }
1.237 @@ -317,9 +506,11 @@
1.238
1.239 const char* tmpdirname = os::get_temp_directory();
1.240
1.241 + // open the temp directory
1.242 DIR* tmpdirp = os::opendir(tmpdirname);
1.243
1.244 if (tmpdirp == NULL) {
1.245 + // Cannot open the directory to get the user name, return.
1.246 return NULL;
1.247 }
1.248
1.249 @@ -344,7 +535,8 @@
1.250 strcat(usrdir_name, "/");
1.251 strcat(usrdir_name, dentry->d_name);
1.252
1.253 - DIR* subdirp = os::opendir(usrdir_name);
1.254 + // open the user directory
1.255 + DIR* subdirp = open_directory_secure(usrdir_name);
1.256
1.257 if (subdirp == NULL) {
1.258 FREE_C_HEAP_ARRAY(char, usrdir_name, mtInternal);
1.259 @@ -465,26 +657,6 @@
1.260 }
1.261
1.262
1.263 -// remove file
1.264 -//
1.265 -// this method removes the file with the given file name in the
1.266 -// named directory.
1.267 -//
1.268 -static void remove_file(const char* dirname, const char* filename) {
1.269 -
1.270 - size_t nbytes = strlen(dirname) + strlen(filename) + 2;
1.271 - char* path = NEW_C_HEAP_ARRAY(char, nbytes, mtInternal);
1.272 -
1.273 - strcpy(path, dirname);
1.274 - strcat(path, "/");
1.275 - strcat(path, filename);
1.276 -
1.277 - remove_file(path);
1.278 -
1.279 - FREE_C_HEAP_ARRAY(char, path, mtInternal);
1.280 -}
1.281 -
1.282 -
1.283 // cleanup stale shared memory resources
1.284 //
1.285 // This method attempts to remove all stale shared memory files in
1.286 @@ -496,16 +668,11 @@
1.287 //
1.288 static void cleanup_sharedmem_resources(const char* dirname) {
1.289
1.290 - // open the user temp directory
1.291 - DIR* dirp = os::opendir(dirname);
1.292 -
1.293 + int saved_cwd_fd;
1.294 + // open the directory
1.295 + DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
1.296 if (dirp == NULL) {
1.297 - // directory doesn't exist, so there is nothing to cleanup
1.298 - return;
1.299 - }
1.300 -
1.301 - if (!is_directory_secure(dirname)) {
1.302 - // the directory is not a secure directory
1.303 + // directory doesn't exist or is insecure, so there is nothing to cleanup
1.304 return;
1.305 }
1.306
1.307 @@ -519,6 +686,7 @@
1.308 //
1.309 struct dirent* entry;
1.310 char* dbuf = NEW_C_HEAP_ARRAY(char, os::readdir_buf_size(dirname), mtInternal);
1.311 +
1.312 errno = 0;
1.313 while ((entry = os::readdir(dirp, (struct dirent *)dbuf)) != NULL) {
1.314
1.315 @@ -527,9 +695,8 @@
1.316 if (pid == 0) {
1.317
1.318 if (strcmp(entry->d_name, ".") != 0 && strcmp(entry->d_name, "..") != 0) {
1.319 -
1.320 // attempt to remove all unexpected files, except "." and ".."
1.321 - remove_file(dirname, entry->d_name);
1.322 + unlink(entry->d_name);
1.323 }
1.324
1.325 errno = 0;
1.326 @@ -551,12 +718,14 @@
1.327 //
1.328 if ((pid == os::current_process_id()) ||
1.329 (kill(pid, 0) == OS_ERR && (errno == ESRCH || errno == EPERM))) {
1.330 -
1.331 - remove_file(dirname, entry->d_name);
1.332 + unlink(entry->d_name);
1.333 }
1.334 errno = 0;
1.335 }
1.336 - os::closedir(dirp);
1.337 +
1.338 + // close the directory and reset the current working directory
1.339 + close_directory_secure_cwd(dirp, saved_cwd_fd);
1.340 +
1.341 FREE_C_HEAP_ARRAY(char, dbuf, mtInternal);
1.342 }
1.343
1.344 @@ -613,19 +782,54 @@
1.345 return -1;
1.346 }
1.347
1.348 + int saved_cwd_fd;
1.349 + // open the directory and set the current working directory to it
1.350 + DIR* dirp = open_directory_secure_cwd(dirname, &saved_cwd_fd);
1.351 + if (dirp == NULL) {
1.352 + // Directory doesn't exist or is insecure, so cannot create shared
1.353 + // memory file.
1.354 + return -1;
1.355 + }
1.356 +
1.357 + // Open the filename in the current directory.
1.358 + // Cannot use O_TRUNC here; truncation of an existing file has to happen
1.359 + // after the is_file_secure() check below.
1.360 int result;
1.361 -
1.362 - RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_TRUNC, S_IREAD|S_IWRITE), result);
1.363 + RESTARTABLE(::open(filename, O_RDWR|O_CREAT|O_NOFOLLOW, S_IREAD|S_IWRITE), result);
1.364 if (result == OS_ERR) {
1.365 if (PrintMiscellaneous && Verbose) {
1.366 - warning("could not create file %s: %s\n", filename, strerror(errno));
1.367 + if (errno == ELOOP) {
1.368 + warning("file %s is a symlink and is not secure\n", filename);
1.369 + } else {
1.370 + warning("could not create file %s: %s\n", filename, strerror(errno));
1.371 + }
1.372 }
1.373 + // close the directory and reset the current working directory
1.374 + close_directory_secure_cwd(dirp, saved_cwd_fd);
1.375 +
1.376 return -1;
1.377 }
1.378 + // close the directory and reset the current working directory
1.379 + close_directory_secure_cwd(dirp, saved_cwd_fd);
1.380
1.381 // save the file descriptor
1.382 int fd = result;
1.383
1.384 + // check to see if the file is secure
1.385 + if (!is_file_secure(fd, filename)) {
1.386 + ::close(fd);
1.387 + return -1;
1.388 + }
1.389 +
1.390 + // truncate the file to get rid of any existing data
1.391 + RESTARTABLE(::ftruncate(fd, (off_t)0), result);
1.392 + if (result == OS_ERR) {
1.393 + if (PrintMiscellaneous && Verbose) {
1.394 + warning("could not truncate shared memory file: %s\n", strerror(errno));
1.395 + }
1.396 + ::close(fd);
1.397 + return -1;
1.398 + }
1.399 // set the file size
1.400 RESTARTABLE(::ftruncate(fd, (off_t)size), result);
1.401 if (result == OS_ERR) {
1.402 @@ -683,8 +887,15 @@
1.403 THROW_MSG_(vmSymbols::java_io_IOException(), strerror(errno), OS_ERR);
1.404 }
1.405 }
1.406 + int fd = result;
1.407
1.408 - return result;
1.409 + // check to see if the file is secure
1.410 + if (!is_file_secure(fd, filename)) {
1.411 + ::close(fd);
1.412 + return -1;
1.413 + }
1.414 +
1.415 + return fd;
1.416 }
1.417
1.418 // create a named shared memory region. returns the address of the
1.419 @@ -715,6 +926,13 @@
1.420
1.421 char* dirname = get_user_tmp_dir(user_name);
1.422 char* filename = get_sharedmem_filename(dirname, vmid);
1.423 + // get the short filename
1.424 + char* short_filename = strrchr(filename, '/');
1.425 + if (short_filename == NULL) {
1.426 + short_filename = filename;
1.427 + } else {
1.428 + short_filename++;
1.429 + }
1.430
1.431 // cleanup any stale shared memory files
1.432 cleanup_sharedmem_resources(dirname);
1.433 @@ -722,7 +940,7 @@
1.434 assert(((size > 0) && (size % os::vm_page_size() == 0)),
1.435 "unexpected PerfMemory region size");
1.436
1.437 - fd = create_sharedmem_resources(dirname, filename, size);
1.438 + fd = create_sharedmem_resources(dirname, short_filename, size);
1.439
1.440 FREE_C_HEAP_ARRAY(char, user_name, mtInternal);
1.441 FREE_C_HEAP_ARRAY(char, dirname, mtInternal);
1.442 @@ -837,12 +1055,12 @@
1.443 // constructs for the file and the shared memory mapping.
1.444 if (mode == PerfMemory::PERF_MODE_RO) {
1.445 mmap_prot = PROT_READ;
1.446 - file_flags = O_RDONLY;
1.447 + file_flags = O_RDONLY | O_NOFOLLOW;
1.448 }
1.449 else if (mode == PerfMemory::PERF_MODE_RW) {
1.450 #ifdef LATER
1.451 mmap_prot = PROT_READ | PROT_WRITE;
1.452 - file_flags = O_RDWR;
1.453 + file_flags = O_RDWR | O_NOFOLLOW;
1.454 #else
1.455 THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(),
1.456 "Unsupported access mode");
