--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/os/bsd/vm/attachListener_bsd.cpp Sun Sep 25 16:03:29 2011 -0700
@@ -0,0 +1,520 @@
+/*
+ * Copyright (c) 2005, 2010, 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 "runtime/interfaceSupport.hpp"
+#include "runtime/os.hpp"
+#include "services/attachListener.hpp"
+#include "services/dtraceAttacher.hpp"
+
+#include <unistd.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/stat.h>
+
+#ifndef UNIX_PATH_MAX
+#define UNIX_PATH_MAX sizeof(((struct sockaddr_un *)0)->sun_path)
+#endif
+
+// The attach mechanism on Bsd uses a UNIX domain socket. An attach listener
+// thread is created at startup or is created on-demand via a signal from
+// the client tool. The attach listener creates a socket and binds it to a file
+// in the filesystem. The attach listener then acts as a simple (single-
+// threaded) server - it waits for a client to connect, reads the request,
+// executes it, and returns the response to the client via the socket
+// connection.
+//
+// As the socket is a UNIX domain socket it means that only clients on the
+// local machine can connect. In addition there are two other aspects to
+// the security:
+// 1. The well known file that the socket is bound to has permission 400
+// 2. When a client connect, the SO_PEERCRED socket option is used to
+// obtain the credentials of client. We check that the effective uid
+// of the client matches this process.
+
+// forward reference
+class BsdAttachOperation;
+
+class BsdAttachListener: AllStatic {
+ private:
+ // the path to which we bind the UNIX domain socket
+ static char _path[UNIX_PATH_MAX];
+ static bool _has_path;
+
+ // the file descriptor for the listening socket
+ static int _listener;
+
+ static void set_path(char* path) {
+ if (path == NULL) {
+ _has_path = false;
+ } else {
+ strncpy(_path, path, UNIX_PATH_MAX);
+ _path[UNIX_PATH_MAX-1] = '\0';
+ _has_path = true;
+ }
+ }
+
+ static void set_listener(int s) { _listener = s; }
+
+ // reads a request from the given connected socket
+ static BsdAttachOperation* read_request(int s);
+
+ public:
+ enum {
+ ATTACH_PROTOCOL_VER = 1 // protocol version
+ };
+ enum {
+ ATTACH_ERROR_BADVERSION = 101 // error codes
+ };
+
+ // initialize the listener, returns 0 if okay
+ static int init();
+
+ static char* path() { return _path; }
+ static bool has_path() { return _has_path; }
+ static int listener() { return _listener; }
+
+ // write the given buffer to a socket
+ static int write_fully(int s, char* buf, int len);
+
+ static BsdAttachOperation* dequeue();
+};
+
+class BsdAttachOperation: public AttachOperation {
+ private:
+ // the connection to the client
+ int _socket;
+
+ public:
+ void complete(jint res, bufferedStream* st);
+
+ void set_socket(int s) { _socket = s; }
+ int socket() const { return _socket; }
+
+ BsdAttachOperation(char* name) : AttachOperation(name) {
+ set_socket(-1);
+ }
+};
+
+// statics
+char BsdAttachListener::_path[UNIX_PATH_MAX];
+bool BsdAttachListener::_has_path;
+int BsdAttachListener::_listener = -1;
+
+// Supporting class to help split a buffer into individual components
+class ArgumentIterator : public StackObj {
+ private:
+ char* _pos;
+ char* _end;
+ public:
+ ArgumentIterator(char* arg_buffer, size_t arg_size) {
+ _pos = arg_buffer;
+ _end = _pos + arg_size - 1;
+ }
+ char* next() {
+ if (*_pos == '\0') {
+ return NULL;
+ }
+ char* res = _pos;
+ char* next_pos = strchr(_pos, '\0');
+ if (next_pos < _end) {
+ next_pos++;
+ }
+ _pos = next_pos;
+ return res;
+ }
+};
+
+
+// atexit hook to stop listener and unlink the file that it is
+// bound too.
+extern "C" {
+ static void listener_cleanup() {
+ static int cleanup_done;
+ if (!cleanup_done) {
+ cleanup_done = 1;
+ int s = BsdAttachListener::listener();
+ if (s != -1) {
+ ::close(s);
+ }
+ if (BsdAttachListener::has_path()) {
+ ::unlink(BsdAttachListener::path());
+ }
+ }
+ }
+}
+
+// Initialization - create a listener socket and bind it to a file
+
+int BsdAttachListener::init() {
+ char path[UNIX_PATH_MAX]; // socket file
+ char initial_path[UNIX_PATH_MAX]; // socket file during setup
+ int listener; // listener socket (file descriptor)
+
+ // register function to cleanup
+ ::atexit(listener_cleanup);
+
+ int n = snprintf(path, UNIX_PATH_MAX, "%s/.java_pid%d",
+ os::get_temp_directory(), os::current_process_id());
+ if (n < (int)UNIX_PATH_MAX) {
+ n = snprintf(initial_path, UNIX_PATH_MAX, "%s.tmp", path);
+ }
+ if (n >= (int)UNIX_PATH_MAX) {
+ return -1;
+ }
+
+ // create the listener socket
+ listener = ::socket(PF_UNIX, SOCK_STREAM, 0);
+ if (listener == -1) {
+ return -1;
+ }
+
+ // bind socket
+ struct sockaddr_un addr;
+ addr.sun_family = AF_UNIX;
+ strcpy(addr.sun_path, initial_path);
+ ::unlink(initial_path);
+ int res = ::bind(listener, (struct sockaddr*)&addr, sizeof(addr));
+ if (res == -1) {
+ RESTARTABLE(::close(listener), res);
+ return -1;
+ }
+
+ // put in listen mode, set permissions, and rename into place
+ res = ::listen(listener, 5);
+ if (res == 0) {
+ RESTARTABLE(::chmod(initial_path, S_IREAD|S_IWRITE), res);
+ if (res == 0) {
+ res = ::rename(initial_path, path);
+ }
+ }
+ if (res == -1) {
+ RESTARTABLE(::close(listener), res);
+ ::unlink(initial_path);
+ return -1;
+ }
+ set_path(path);
+ set_listener(listener);
+
+ return 0;
+}
+
+// Given a socket that is connected to a peer we read the request and
+// create an AttachOperation. As the socket is blocking there is potential
+// for a denial-of-service if the peer does not response. However this happens
+// after the peer credentials have been checked and in the worst case it just
+// means that the attach listener thread is blocked.
+//
+BsdAttachOperation* BsdAttachListener::read_request(int s) {
+ char ver_str[8];
+ sprintf(ver_str, "%d", ATTACH_PROTOCOL_VER);
+
+ // The request is a sequence of strings so we first figure out the
+ // expected count and the maximum possible length of the request.
+ // The request is:
+ // <ver>0<cmd>0<arg>0<arg>0<arg>0
+ // where <ver> is the protocol version (1), <cmd> is the command
+ // name ("load", "datadump", ...), and <arg> is an argument
+ int expected_str_count = 2 + AttachOperation::arg_count_max;
+ const int max_len = (sizeof(ver_str) + 1) + (AttachOperation::name_length_max + 1) +
+ AttachOperation::arg_count_max*(AttachOperation::arg_length_max + 1);
+
+ char buf[max_len];
+ int str_count = 0;
+
+ // Read until all (expected) strings have been read, the buffer is
+ // full, or EOF.
+
+ int off = 0;
+ int left = max_len;
+
+ do {
+ int n;
+ RESTARTABLE(read(s, buf+off, left), n);
+ if (n == -1) {
+ return NULL; // reset by peer or other error
+ }
+ if (n == 0) {
+ break;
+ }
+ for (int i=0; i<n; i++) {
+ if (buf[off+i] == 0) {
+ // EOS found
+ str_count++;
+
+ // The first string is <ver> so check it now to
+ // check for protocol mis-match
+ if (str_count == 1) {
+ if ((strlen(buf) != strlen(ver_str)) ||
+ (atoi(buf) != ATTACH_PROTOCOL_VER)) {
+ char msg[32];
+ sprintf(msg, "%d\n", ATTACH_ERROR_BADVERSION);
+ write_fully(s, msg, strlen(msg));
+ return NULL;
+ }
+ }
+ }
+ }
+ off += n;
+ left -= n;
+ } while (left > 0 && str_count < expected_str_count);
+
+ if (str_count != expected_str_count) {
+ return NULL; // incomplete request
+ }
+
+ // parse request
+
+ ArgumentIterator args(buf, (max_len)-left);
+
+ // version already checked
+ char* v = args.next();
+
+ char* name = args.next();
+ if (name == NULL || strlen(name) > AttachOperation::name_length_max) {
+ return NULL;
+ }
+
+ BsdAttachOperation* op = new BsdAttachOperation(name);
+
+ for (int i=0; i<AttachOperation::arg_count_max; i++) {
+ char* arg = args.next();
+ if (arg == NULL) {
+ op->set_arg(i, NULL);
+ } else {
+ if (strlen(arg) > AttachOperation::arg_length_max) {
+ delete op;
+ return NULL;
+ }
+ op->set_arg(i, arg);
+ }
+ }
+
+ op->set_socket(s);
+ return op;
+}
+
+
+// Dequeue an operation
+//
+// In the Bsd implementation there is only a single operation and clients
+// cannot queue commands (except at the socket level).
+//
+BsdAttachOperation* BsdAttachListener::dequeue() {
+ for (;;) {
+ int s;
+
+ // wait for client to connect
+ struct sockaddr addr;
+ socklen_t len = sizeof(addr);
+ RESTARTABLE(::accept(listener(), &addr, &len), s);
+ if (s == -1) {
+ return NULL; // log a warning?
+ }
+
+ // get the credentials of the peer and check the effective uid/guid
+ // - check with jeff on this.
+#ifdef _ALLBSD_SOURCE
+ uid_t puid;
+ gid_t pgid;
+ if (::getpeereid(s, &puid, &pgid) != 0) {
+ int res;
+ RESTARTABLE(::close(s), res);
+ continue;
+ }
+#else
+ struct ucred cred_info;
+ socklen_t optlen = sizeof(cred_info);
+ if (::getsockopt(s, SOL_SOCKET, SO_PEERCRED, (void*)&cred_info, &optlen) == -1) {
+ int res;
+ RESTARTABLE(::close(s), res);
+ continue;
+ }
+ uid_t puid = cred_info.uid;
+ gid_t pgid = cred_info.gid;
+#endif
+ uid_t euid = geteuid();
+ gid_t egid = getegid();
+
+ if (puid != euid || pgid != egid) {
+ int res;
+ RESTARTABLE(::close(s), res);
+ continue;
+ }
+
+ // peer credential look okay so we read the request
+ BsdAttachOperation* op = read_request(s);
+ if (op == NULL) {
+ int res;
+ RESTARTABLE(::close(s), res);
+ continue;
+ } else {
+ return op;
+ }
+ }
+}
+
+// write the given buffer to the socket
+int BsdAttachListener::write_fully(int s, char* buf, int len) {
+ do {
+ int n = ::write(s, buf, len);
+ if (n == -1) {
+ if (errno != EINTR) return -1;
+ } else {
+ buf += n;
+ len -= n;
+ }
+ }
+ while (len > 0);
+ return 0;
+}
+
+// Complete an operation by sending the operation result and any result
+// output to the client. At this time the socket is in blocking mode so
+// potentially we can block if there is a lot of data and the client is
+// non-responsive. For most operations this is a non-issue because the
+// default send buffer is sufficient to buffer everything. In the future
+// if there are operations that involves a very big reply then it the
+// socket could be made non-blocking and a timeout could be used.
+
+void BsdAttachOperation::complete(jint result, bufferedStream* st) {
+ JavaThread* thread = JavaThread::current();
+ ThreadBlockInVM tbivm(thread);
+
+ thread->set_suspend_equivalent();
+ // cleared by handle_special_suspend_equivalent_condition() or
+ // java_suspend_self() via check_and_wait_while_suspended()
+
+ // write operation result
+ char msg[32];
+ sprintf(msg, "%d\n", result);
+ int rc = BsdAttachListener::write_fully(this->socket(), msg, strlen(msg));
+
+ // write any result data
+ if (rc == 0) {
+ BsdAttachListener::write_fully(this->socket(), (char*) st->base(), st->size());
+ ::shutdown(this->socket(), 2);
+ }
+
+ // done
+ RESTARTABLE(::close(this->socket()), rc);
+
+ // were we externally suspended while we were waiting?
+ thread->check_and_wait_while_suspended();
+
+ delete this;
+}
+
+
+// AttachListener functions
+
+AttachOperation* AttachListener::dequeue() {
+ JavaThread* thread = JavaThread::current();
+ ThreadBlockInVM tbivm(thread);
+
+ thread->set_suspend_equivalent();
+ // cleared by handle_special_suspend_equivalent_condition() or
+ // java_suspend_self() via check_and_wait_while_suspended()
+
+ AttachOperation* op = BsdAttachListener::dequeue();
+
+ // were we externally suspended while we were waiting?
+ thread->check_and_wait_while_suspended();
+
+ return op;
+}
+
+int AttachListener::pd_init() {
+ JavaThread* thread = JavaThread::current();
+ ThreadBlockInVM tbivm(thread);
+
+ thread->set_suspend_equivalent();
+ // cleared by handle_special_suspend_equivalent_condition() or
+ // java_suspend_self() via check_and_wait_while_suspended()
+
+ int ret_code = BsdAttachListener::init();
+
+ // were we externally suspended while we were waiting?
+ thread->check_and_wait_while_suspended();
+
+ return ret_code;
+}
+
+// Attach Listener is started lazily except in the case when
+// +ReduseSignalUsage is used
+bool AttachListener::init_at_startup() {
+ if (ReduceSignalUsage) {
+ return true;
+ } else {
+ return false;
+ }
+}
+
+// If the file .attach_pid<pid> exists in the working directory
+// or /tmp then this is the trigger to start the attach mechanism
+bool AttachListener::is_init_trigger() {
+ if (init_at_startup() || is_initialized()) {
+ return false; // initialized at startup or already initialized
+ }
+ char path[PATH_MAX + 1];
+ int ret;
+ struct stat st;
+
+ snprintf(path, PATH_MAX + 1, "%s/.attach_pid%d",
+ os::get_temp_directory(), os::current_process_id());
+ RESTARTABLE(::stat(path, &st), ret);
+ if (ret == 0) {
+ // simple check to avoid starting the attach mechanism when
+ // a bogus user creates the file
+ if (st.st_uid == geteuid()) {
+ init();
+ return true;
+ }
+ }
+ return false;
+}
+
+// if VM aborts then remove listener
+void AttachListener::abort() {
+ listener_cleanup();
+}
+
+void AttachListener::pd_data_dump() {
+ os::signal_notify(SIGQUIT);
+}
+
+AttachOperationFunctionInfo* AttachListener::pd_find_operation(const char* n) {
+ return NULL;
+}
+
+jint AttachListener::pd_set_flag(AttachOperation* op, outputStream* out) {
+ out->print_cr("flag '%s' cannot be changed", op->arg(0));
+ return JNI_ERR;
+}
+
+void AttachListener::pd_detachall() {
+ // do nothing for now
+}