Thu, 24 May 2018 17:06:56 +0800
Merge
1 /*
2 * Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #include "precompiled.hpp"
26 #include "runtime/interfaceSupport.hpp"
27 #include "runtime/os.hpp"
28 #include "services/attachListener.hpp"
29 #include "services/dtraceAttacher.hpp"
31 #include <unistd.h>
32 #include <signal.h>
33 #include <sys/types.h>
34 #include <sys/socket.h>
35 #include <sys/un.h>
36 #include <sys/stat.h>
38 #ifndef UNIX_PATH_MAX
39 #define UNIX_PATH_MAX sizeof(((struct sockaddr_un *)0)->sun_path)
40 #endif
42 // The attach mechanism on Bsd uses a UNIX domain socket. An attach listener
43 // thread is created at startup or is created on-demand via a signal from
44 // the client tool. The attach listener creates a socket and binds it to a file
45 // in the filesystem. The attach listener then acts as a simple (single-
46 // threaded) server - it waits for a client to connect, reads the request,
47 // executes it, and returns the response to the client via the socket
48 // connection.
49 //
50 // As the socket is a UNIX domain socket it means that only clients on the
51 // local machine can connect. In addition there are two other aspects to
52 // the security:
53 // 1. The well known file that the socket is bound to has permission 400
54 // 2. When a client connect, the SO_PEERCRED socket option is used to
55 // obtain the credentials of client. We check that the effective uid
56 // of the client matches this process.
58 // forward reference
59 class BsdAttachOperation;
61 class BsdAttachListener: AllStatic {
62 private:
63 // the path to which we bind the UNIX domain socket
64 static char _path[UNIX_PATH_MAX];
65 static bool _has_path;
67 // the file descriptor for the listening socket
68 static int _listener;
70 static void set_path(char* path) {
71 if (path == NULL) {
72 _has_path = false;
73 } else {
74 strncpy(_path, path, UNIX_PATH_MAX);
75 _path[UNIX_PATH_MAX-1] = '\0';
76 _has_path = true;
77 }
78 }
80 static void set_listener(int s) { _listener = s; }
82 // reads a request from the given connected socket
83 static BsdAttachOperation* read_request(int s);
85 public:
86 enum {
87 ATTACH_PROTOCOL_VER = 1 // protocol version
88 };
89 enum {
90 ATTACH_ERROR_BADVERSION = 101 // error codes
91 };
93 // initialize the listener, returns 0 if okay
94 static int init();
96 static char* path() { return _path; }
97 static bool has_path() { return _has_path; }
98 static int listener() { return _listener; }
100 // write the given buffer to a socket
101 static int write_fully(int s, char* buf, int len);
103 static BsdAttachOperation* dequeue();
104 };
106 class BsdAttachOperation: public AttachOperation {
107 private:
108 // the connection to the client
109 int _socket;
111 public:
112 void complete(jint res, bufferedStream* st);
114 void set_socket(int s) { _socket = s; }
115 int socket() const { return _socket; }
117 BsdAttachOperation(char* name) : AttachOperation(name) {
118 set_socket(-1);
119 }
120 };
122 // statics
123 char BsdAttachListener::_path[UNIX_PATH_MAX];
124 bool BsdAttachListener::_has_path;
125 int BsdAttachListener::_listener = -1;
127 // Supporting class to help split a buffer into individual components
128 class ArgumentIterator : public StackObj {
129 private:
130 char* _pos;
131 char* _end;
132 public:
133 ArgumentIterator(char* arg_buffer, size_t arg_size) {
134 _pos = arg_buffer;
135 _end = _pos + arg_size - 1;
136 }
137 char* next() {
138 if (*_pos == '\0') {
139 return NULL;
140 }
141 char* res = _pos;
142 char* next_pos = strchr(_pos, '\0');
143 if (next_pos < _end) {
144 next_pos++;
145 }
146 _pos = next_pos;
147 return res;
148 }
149 };
152 // atexit hook to stop listener and unlink the file that it is
153 // bound too.
154 extern "C" {
155 static void listener_cleanup() {
156 static int cleanup_done;
157 if (!cleanup_done) {
158 cleanup_done = 1;
159 int s = BsdAttachListener::listener();
160 if (s != -1) {
161 ::close(s);
162 }
163 if (BsdAttachListener::has_path()) {
164 ::unlink(BsdAttachListener::path());
165 }
166 }
167 }
168 }
170 // Initialization - create a listener socket and bind it to a file
172 int BsdAttachListener::init() {
173 char path[UNIX_PATH_MAX]; // socket file
174 char initial_path[UNIX_PATH_MAX]; // socket file during setup
175 int listener; // listener socket (file descriptor)
177 // register function to cleanup
178 ::atexit(listener_cleanup);
180 int n = snprintf(path, UNIX_PATH_MAX, "%s/.java_pid%d",
181 os::get_temp_directory(), os::current_process_id());
182 if (n < (int)UNIX_PATH_MAX) {
183 n = snprintf(initial_path, UNIX_PATH_MAX, "%s.tmp", path);
184 }
185 if (n >= (int)UNIX_PATH_MAX) {
186 return -1;
187 }
189 // create the listener socket
190 listener = ::socket(PF_UNIX, SOCK_STREAM, 0);
191 if (listener == -1) {
192 return -1;
193 }
195 // bind socket
196 struct sockaddr_un addr;
197 addr.sun_family = AF_UNIX;
198 strcpy(addr.sun_path, initial_path);
199 ::unlink(initial_path);
200 int res = ::bind(listener, (struct sockaddr*)&addr, sizeof(addr));
201 if (res == -1) {
202 ::close(listener);
203 return -1;
204 }
206 // put in listen mode, set permissions, and rename into place
207 res = ::listen(listener, 5);
208 if (res == 0) {
209 RESTARTABLE(::chmod(initial_path, S_IREAD|S_IWRITE), res);
210 if (res == 0) {
211 // make sure the file is owned by the effective user and effective group
212 // (this is the default on linux, but not on mac os)
213 RESTARTABLE(::chown(initial_path, geteuid(), getegid()), res);
214 if (res == 0) {
215 res = ::rename(initial_path, path);
216 }
217 }
218 }
219 if (res == -1) {
220 ::close(listener);
221 ::unlink(initial_path);
222 return -1;
223 }
224 set_path(path);
225 set_listener(listener);
227 return 0;
228 }
230 // Given a socket that is connected to a peer we read the request and
231 // create an AttachOperation. As the socket is blocking there is potential
232 // for a denial-of-service if the peer does not response. However this happens
233 // after the peer credentials have been checked and in the worst case it just
234 // means that the attach listener thread is blocked.
235 //
236 BsdAttachOperation* BsdAttachListener::read_request(int s) {
237 char ver_str[8];
238 sprintf(ver_str, "%d", ATTACH_PROTOCOL_VER);
240 // The request is a sequence of strings so we first figure out the
241 // expected count and the maximum possible length of the request.
242 // The request is:
243 // <ver>0<cmd>0<arg>0<arg>0<arg>0
244 // where <ver> is the protocol version (1), <cmd> is the command
245 // name ("load", "datadump", ...), and <arg> is an argument
246 int expected_str_count = 2 + AttachOperation::arg_count_max;
247 const int max_len = (sizeof(ver_str) + 1) + (AttachOperation::name_length_max + 1) +
248 AttachOperation::arg_count_max*(AttachOperation::arg_length_max + 1);
250 char buf[max_len];
251 int str_count = 0;
253 // Read until all (expected) strings have been read, the buffer is
254 // full, or EOF.
256 int off = 0;
257 int left = max_len;
259 do {
260 int n;
261 RESTARTABLE(read(s, buf+off, left), n);
262 if (n == -1) {
263 return NULL; // reset by peer or other error
264 }
265 if (n == 0) {
266 break;
267 }
268 for (int i=0; i<n; i++) {
269 if (buf[off+i] == 0) {
270 // EOS found
271 str_count++;
273 // The first string is <ver> so check it now to
274 // check for protocol mis-match
275 if (str_count == 1) {
276 if ((strlen(buf) != strlen(ver_str)) ||
277 (atoi(buf) != ATTACH_PROTOCOL_VER)) {
278 char msg[32];
279 sprintf(msg, "%d\n", ATTACH_ERROR_BADVERSION);
280 write_fully(s, msg, strlen(msg));
281 return NULL;
282 }
283 }
284 }
285 }
286 off += n;
287 left -= n;
288 } while (left > 0 && str_count < expected_str_count);
290 if (str_count != expected_str_count) {
291 return NULL; // incomplete request
292 }
294 // parse request
296 ArgumentIterator args(buf, (max_len)-left);
298 // version already checked
299 char* v = args.next();
301 char* name = args.next();
302 if (name == NULL || strlen(name) > AttachOperation::name_length_max) {
303 return NULL;
304 }
306 BsdAttachOperation* op = new BsdAttachOperation(name);
308 for (int i=0; i<AttachOperation::arg_count_max; i++) {
309 char* arg = args.next();
310 if (arg == NULL) {
311 op->set_arg(i, NULL);
312 } else {
313 if (strlen(arg) > AttachOperation::arg_length_max) {
314 delete op;
315 return NULL;
316 }
317 op->set_arg(i, arg);
318 }
319 }
321 op->set_socket(s);
322 return op;
323 }
326 // Dequeue an operation
327 //
328 // In the Bsd implementation there is only a single operation and clients
329 // cannot queue commands (except at the socket level).
330 //
331 BsdAttachOperation* BsdAttachListener::dequeue() {
332 for (;;) {
333 int s;
335 // wait for client to connect
336 struct sockaddr addr;
337 socklen_t len = sizeof(addr);
338 RESTARTABLE(::accept(listener(), &addr, &len), s);
339 if (s == -1) {
340 return NULL; // log a warning?
341 }
343 // get the credentials of the peer and check the effective uid/guid
344 // - check with jeff on this.
345 uid_t puid;
346 gid_t pgid;
347 if (::getpeereid(s, &puid, &pgid) != 0) {
348 ::close(s);
349 continue;
350 }
351 uid_t euid = geteuid();
352 gid_t egid = getegid();
354 if (puid != euid || pgid != egid) {
355 ::close(s);
356 continue;
357 }
359 // peer credential look okay so we read the request
360 BsdAttachOperation* op = read_request(s);
361 if (op == NULL) {
362 ::close(s);
363 continue;
364 } else {
365 return op;
366 }
367 }
368 }
370 // write the given buffer to the socket
371 int BsdAttachListener::write_fully(int s, char* buf, int len) {
372 do {
373 int n = ::write(s, buf, len);
374 if (n == -1) {
375 if (errno != EINTR) return -1;
376 } else {
377 buf += n;
378 len -= n;
379 }
380 }
381 while (len > 0);
382 return 0;
383 }
385 // Complete an operation by sending the operation result and any result
386 // output to the client. At this time the socket is in blocking mode so
387 // potentially we can block if there is a lot of data and the client is
388 // non-responsive. For most operations this is a non-issue because the
389 // default send buffer is sufficient to buffer everything. In the future
390 // if there are operations that involves a very big reply then it the
391 // socket could be made non-blocking and a timeout could be used.
393 void BsdAttachOperation::complete(jint result, bufferedStream* st) {
394 JavaThread* thread = JavaThread::current();
395 ThreadBlockInVM tbivm(thread);
397 thread->set_suspend_equivalent();
398 // cleared by handle_special_suspend_equivalent_condition() or
399 // java_suspend_self() via check_and_wait_while_suspended()
401 // write operation result
402 char msg[32];
403 sprintf(msg, "%d\n", result);
404 int rc = BsdAttachListener::write_fully(this->socket(), msg, strlen(msg));
406 // write any result data
407 if (rc == 0) {
408 BsdAttachListener::write_fully(this->socket(), (char*) st->base(), st->size());
409 ::shutdown(this->socket(), 2);
410 }
412 // done
413 ::close(this->socket());
415 // were we externally suspended while we were waiting?
416 thread->check_and_wait_while_suspended();
418 delete this;
419 }
422 // AttachListener functions
424 AttachOperation* AttachListener::dequeue() {
425 JavaThread* thread = JavaThread::current();
426 ThreadBlockInVM tbivm(thread);
428 thread->set_suspend_equivalent();
429 // cleared by handle_special_suspend_equivalent_condition() or
430 // java_suspend_self() via check_and_wait_while_suspended()
432 AttachOperation* op = BsdAttachListener::dequeue();
434 // were we externally suspended while we were waiting?
435 thread->check_and_wait_while_suspended();
437 return op;
438 }
441 // Performs initialization at vm startup
442 // For BSD we remove any stale .java_pid file which could cause
443 // an attaching process to think we are ready to receive on the
444 // domain socket before we are properly initialized
446 void AttachListener::vm_start() {
447 char fn[UNIX_PATH_MAX];
448 struct stat st;
449 int ret;
451 int n = snprintf(fn, UNIX_PATH_MAX, "%s/.java_pid%d",
452 os::get_temp_directory(), os::current_process_id());
453 assert(n < (int)UNIX_PATH_MAX, "java_pid file name buffer overflow");
455 RESTARTABLE(::stat(fn, &st), ret);
456 if (ret == 0) {
457 ret = ::unlink(fn);
458 if (ret == -1) {
459 debug_only(warning("failed to remove stale attach pid file at %s", fn));
460 }
461 }
462 }
464 int AttachListener::pd_init() {
465 JavaThread* thread = JavaThread::current();
466 ThreadBlockInVM tbivm(thread);
468 thread->set_suspend_equivalent();
469 // cleared by handle_special_suspend_equivalent_condition() or
470 // java_suspend_self() via check_and_wait_while_suspended()
472 int ret_code = BsdAttachListener::init();
474 // were we externally suspended while we were waiting?
475 thread->check_and_wait_while_suspended();
477 return ret_code;
478 }
480 // Attach Listener is started lazily except in the case when
481 // +ReduseSignalUsage is used
482 bool AttachListener::init_at_startup() {
483 if (ReduceSignalUsage) {
484 return true;
485 } else {
486 return false;
487 }
488 }
490 // If the file .attach_pid<pid> exists in the working directory
491 // or /tmp then this is the trigger to start the attach mechanism
492 bool AttachListener::is_init_trigger() {
493 if (init_at_startup() || is_initialized()) {
494 return false; // initialized at startup or already initialized
495 }
496 char path[PATH_MAX + 1];
497 int ret;
498 struct stat st;
500 snprintf(path, PATH_MAX + 1, "%s/.attach_pid%d",
501 os::get_temp_directory(), os::current_process_id());
502 RESTARTABLE(::stat(path, &st), ret);
503 if (ret == 0) {
504 // simple check to avoid starting the attach mechanism when
505 // a bogus user creates the file
506 if (st.st_uid == geteuid()) {
507 init();
508 return true;
509 }
510 }
511 return false;
512 }
514 // if VM aborts then remove listener
515 void AttachListener::abort() {
516 listener_cleanup();
517 }
519 void AttachListener::pd_data_dump() {
520 os::signal_notify(SIGQUIT);
521 }
523 AttachOperationFunctionInfo* AttachListener::pd_find_operation(const char* n) {
524 return NULL;
525 }
527 jint AttachListener::pd_set_flag(AttachOperation* op, outputStream* out) {
528 out->print_cr("flag '%s' cannot be changed", op->arg(0));
529 return JNI_ERR;
530 }
532 void AttachListener::pd_detachall() {
533 // do nothing for now
534 }