never@3156: /*
sla@3648:  * Copyright (c) 2005, 2012, Oracle and/or its affiliates. All rights reserved.
never@3156:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
never@3156:  *
never@3156:  * This code is free software; you can redistribute it and/or modify it
never@3156:  * under the terms of the GNU General Public License version 2 only, as
never@3156:  * published by the Free Software Foundation.
never@3156:  *
never@3156:  * This code is distributed in the hope that it will be useful, but WITHOUT
never@3156:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
never@3156:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
never@3156:  * version 2 for more details (a copy is included in the LICENSE file that
never@3156:  * accompanied this code).
never@3156:  *
never@3156:  * You should have received a copy of the GNU General Public License version
never@3156:  * 2 along with this work; if not, write to the Free Software Foundation,
never@3156:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
never@3156:  *
never@3156:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
never@3156:  * or visit www.oracle.com if you need additional information or have any
never@3156:  * questions.
never@3156:  *
never@3156:  */
never@3156: 
never@3156: #include "precompiled.hpp"
never@3156: #include "runtime/interfaceSupport.hpp"
never@3156: #include "runtime/os.hpp"
never@3156: #include "services/attachListener.hpp"
never@3156: #include "services/dtraceAttacher.hpp"
never@3156: 
never@3156: #include <unistd.h>
never@3156: #include <signal.h>
never@3156: #include <sys/types.h>
never@3156: #include <sys/socket.h>
never@3156: #include <sys/un.h>
never@3156: #include <sys/stat.h>
never@3156: 
never@3156: #ifndef UNIX_PATH_MAX
never@3156: #define UNIX_PATH_MAX   sizeof(((struct sockaddr_un *)0)->sun_path)
never@3156: #endif
never@3156: 
never@3156: // The attach mechanism on Bsd uses a UNIX domain socket. An attach listener
never@3156: // thread is created at startup or is created on-demand via a signal from
never@3156: // the client tool. The attach listener creates a socket and binds it to a file
never@3156: // in the filesystem. The attach listener then acts as a simple (single-
never@3156: // threaded) server - it waits for a client to connect, reads the request,
never@3156: // executes it, and returns the response to the client via the socket
never@3156: // connection.
never@3156: //
never@3156: // As the socket is a UNIX domain socket it means that only clients on the
never@3156: // local machine can connect. In addition there are two other aspects to
never@3156: // the security:
never@3156: // 1. The well known file that the socket is bound to has permission 400
never@3156: // 2. When a client connect, the SO_PEERCRED socket option is used to
never@3156: //    obtain the credentials of client. We check that the effective uid
never@3156: //    of the client matches this process.
never@3156: 
never@3156: // forward reference
never@3156: class BsdAttachOperation;
never@3156: 
never@3156: class BsdAttachListener: AllStatic {
never@3156:  private:
never@3156:   // the path to which we bind the UNIX domain socket
never@3156:   static char _path[UNIX_PATH_MAX];
never@3156:   static bool _has_path;
never@3156: 
never@3156:   // the file descriptor for the listening socket
never@3156:   static int _listener;
never@3156: 
never@3156:   static void set_path(char* path) {
never@3156:     if (path == NULL) {
never@3156:       _has_path = false;
never@3156:     } else {
never@3156:       strncpy(_path, path, UNIX_PATH_MAX);
never@3156:       _path[UNIX_PATH_MAX-1] = '\0';
never@3156:       _has_path = true;
never@3156:     }
never@3156:   }
never@3156: 
never@3156:   static void set_listener(int s)               { _listener = s; }
never@3156: 
never@3156:   // reads a request from the given connected socket
never@3156:   static BsdAttachOperation* read_request(int s);
never@3156: 
never@3156:  public:
never@3156:   enum {
never@3156:     ATTACH_PROTOCOL_VER = 1                     // protocol version
never@3156:   };
never@3156:   enum {
never@3156:     ATTACH_ERROR_BADVERSION     = 101           // error codes
never@3156:   };
never@3156: 
never@3156:   // initialize the listener, returns 0 if okay
never@3156:   static int init();
never@3156: 
never@3156:   static char* path()                   { return _path; }
never@3156:   static bool has_path()                { return _has_path; }
never@3156:   static int listener()                 { return _listener; }
never@3156: 
never@3156:   // write the given buffer to a socket
never@3156:   static int write_fully(int s, char* buf, int len);
never@3156: 
never@3156:   static BsdAttachOperation* dequeue();
never@3156: };
never@3156: 
never@3156: class BsdAttachOperation: public AttachOperation {
never@3156:  private:
never@3156:   // the connection to the client
never@3156:   int _socket;
never@3156: 
never@3156:  public:
never@3156:   void complete(jint res, bufferedStream* st);
never@3156: 
never@3156:   void set_socket(int s)                                { _socket = s; }
never@3156:   int socket() const                                    { return _socket; }
never@3156: 
never@3156:   BsdAttachOperation(char* name) : AttachOperation(name) {
never@3156:     set_socket(-1);
never@3156:   }
never@3156: };
never@3156: 
never@3156: // statics
never@3156: char BsdAttachListener::_path[UNIX_PATH_MAX];
never@3156: bool BsdAttachListener::_has_path;
never@3156: int BsdAttachListener::_listener = -1;
never@3156: 
never@3156: // Supporting class to help split a buffer into individual components
never@3156: class ArgumentIterator : public StackObj {
never@3156:  private:
never@3156:   char* _pos;
never@3156:   char* _end;
never@3156:  public:
never@3156:   ArgumentIterator(char* arg_buffer, size_t arg_size) {
never@3156:     _pos = arg_buffer;
never@3156:     _end = _pos + arg_size - 1;
never@3156:   }
never@3156:   char* next() {
never@3156:     if (*_pos == '\0') {
never@3156:       return NULL;
never@3156:     }
never@3156:     char* res = _pos;
never@3156:     char* next_pos = strchr(_pos, '\0');
never@3156:     if (next_pos < _end)  {
never@3156:       next_pos++;
never@3156:     }
never@3156:     _pos = next_pos;
never@3156:     return res;
never@3156:   }
never@3156: };
never@3156: 
never@3156: 
never@3156: // atexit hook to stop listener and unlink the file that it is
never@3156: // bound too.
never@3156: extern "C" {
never@3156:   static void listener_cleanup() {
never@3156:     static int cleanup_done;
never@3156:     if (!cleanup_done) {
never@3156:       cleanup_done = 1;
never@3156:       int s = BsdAttachListener::listener();
never@3156:       if (s != -1) {
never@3156:         ::close(s);
never@3156:       }
never@3156:       if (BsdAttachListener::has_path()) {
never@3156:         ::unlink(BsdAttachListener::path());
never@3156:       }
never@3156:     }
never@3156:   }
never@3156: }
never@3156: 
never@3156: // Initialization - create a listener socket and bind it to a file
never@3156: 
never@3156: int BsdAttachListener::init() {
never@3156:   char path[UNIX_PATH_MAX];          // socket file
never@3156:   char initial_path[UNIX_PATH_MAX];  // socket file during setup
never@3156:   int listener;                      // listener socket (file descriptor)
never@3156: 
never@3156:   // register function to cleanup
never@3156:   ::atexit(listener_cleanup);
never@3156: 
never@3156:   int n = snprintf(path, UNIX_PATH_MAX, "%s/.java_pid%d",
never@3156:                    os::get_temp_directory(), os::current_process_id());
never@3156:   if (n < (int)UNIX_PATH_MAX) {
never@3156:     n = snprintf(initial_path, UNIX_PATH_MAX, "%s.tmp", path);
never@3156:   }
never@3156:   if (n >= (int)UNIX_PATH_MAX) {
never@3156:     return -1;
never@3156:   }
never@3156: 
never@3156:   // create the listener socket
never@3156:   listener = ::socket(PF_UNIX, SOCK_STREAM, 0);
never@3156:   if (listener == -1) {
never@3156:     return -1;
never@3156:   }
never@3156: 
never@3156:   // bind socket
never@3156:   struct sockaddr_un addr;
never@3156:   addr.sun_family = AF_UNIX;
never@3156:   strcpy(addr.sun_path, initial_path);
never@3156:   ::unlink(initial_path);
never@3156:   int res = ::bind(listener, (struct sockaddr*)&addr, sizeof(addr));
never@3156:   if (res == -1) {
never@3156:     RESTARTABLE(::close(listener), res);
never@3156:     return -1;
never@3156:   }
never@3156: 
never@3156:   // put in listen mode, set permissions, and rename into place
never@3156:   res = ::listen(listener, 5);
never@3156:   if (res == 0) {
sla@3648:     RESTARTABLE(::chmod(initial_path, S_IREAD|S_IWRITE), res);
sla@3648:     if (res == 0) {
sla@3648:       // make sure the file is owned by the effective user and effective group
sla@3648:       // (this is the default on linux, but not on mac os)
sla@3648:       RESTARTABLE(::chown(initial_path, geteuid(), getegid()), res);
never@3156:       if (res == 0) {
sla@3648:         res = ::rename(initial_path, path);
never@3156:       }
sla@3648:     }
never@3156:   }
never@3156:   if (res == -1) {
never@3156:     RESTARTABLE(::close(listener), res);
never@3156:     ::unlink(initial_path);
never@3156:     return -1;
never@3156:   }
never@3156:   set_path(path);
never@3156:   set_listener(listener);
never@3156: 
never@3156:   return 0;
never@3156: }
never@3156: 
never@3156: // Given a socket that is connected to a peer we read the request and
never@3156: // create an AttachOperation. As the socket is blocking there is potential
never@3156: // for a denial-of-service if the peer does not response. However this happens
never@3156: // after the peer credentials have been checked and in the worst case it just
never@3156: // means that the attach listener thread is blocked.
never@3156: //
never@3156: BsdAttachOperation* BsdAttachListener::read_request(int s) {
never@3156:   char ver_str[8];
never@3156:   sprintf(ver_str, "%d", ATTACH_PROTOCOL_VER);
never@3156: 
never@3156:   // The request is a sequence of strings so we first figure out the
never@3156:   // expected count and the maximum possible length of the request.
never@3156:   // The request is:
never@3156:   //   <ver>0<cmd>0<arg>0<arg>0<arg>0
never@3156:   // where <ver> is the protocol version (1), <cmd> is the command
never@3156:   // name ("load", "datadump", ...), and <arg> is an argument
never@3156:   int expected_str_count = 2 + AttachOperation::arg_count_max;
never@3156:   const int max_len = (sizeof(ver_str) + 1) + (AttachOperation::name_length_max + 1) +
never@3156:     AttachOperation::arg_count_max*(AttachOperation::arg_length_max + 1);
never@3156: 
never@3156:   char buf[max_len];
never@3156:   int str_count = 0;
never@3156: 
never@3156:   // Read until all (expected) strings have been read, the buffer is
never@3156:   // full, or EOF.
never@3156: 
never@3156:   int off = 0;
never@3156:   int left = max_len;
never@3156: 
never@3156:   do {
never@3156:     int n;
never@3156:     RESTARTABLE(read(s, buf+off, left), n);
never@3156:     if (n == -1) {
never@3156:       return NULL;      // reset by peer or other error
never@3156:     }
never@3156:     if (n == 0) {
never@3156:       break;
never@3156:     }
never@3156:     for (int i=0; i<n; i++) {
never@3156:       if (buf[off+i] == 0) {
never@3156:         // EOS found
never@3156:         str_count++;
never@3156: 
never@3156:         // The first string is <ver> so check it now to
never@3156:         // check for protocol mis-match
never@3156:         if (str_count == 1) {
never@3156:           if ((strlen(buf) != strlen(ver_str)) ||
never@3156:               (atoi(buf) != ATTACH_PROTOCOL_VER)) {
never@3156:             char msg[32];
never@3156:             sprintf(msg, "%d\n", ATTACH_ERROR_BADVERSION);
never@3156:             write_fully(s, msg, strlen(msg));
never@3156:             return NULL;
never@3156:           }
never@3156:         }
never@3156:       }
never@3156:     }
never@3156:     off += n;
never@3156:     left -= n;
never@3156:   } while (left > 0 && str_count < expected_str_count);
never@3156: 
never@3156:   if (str_count != expected_str_count) {
never@3156:     return NULL;        // incomplete request
never@3156:   }
never@3156: 
never@3156:   // parse request
never@3156: 
never@3156:   ArgumentIterator args(buf, (max_len)-left);
never@3156: 
never@3156:   // version already checked
never@3156:   char* v = args.next();
never@3156: 
never@3156:   char* name = args.next();
never@3156:   if (name == NULL || strlen(name) > AttachOperation::name_length_max) {
never@3156:     return NULL;
never@3156:   }
never@3156: 
never@3156:   BsdAttachOperation* op = new BsdAttachOperation(name);
never@3156: 
never@3156:   for (int i=0; i<AttachOperation::arg_count_max; i++) {
never@3156:     char* arg = args.next();
never@3156:     if (arg == NULL) {
never@3156:       op->set_arg(i, NULL);
never@3156:     } else {
never@3156:       if (strlen(arg) > AttachOperation::arg_length_max) {
never@3156:         delete op;
never@3156:         return NULL;
never@3156:       }
never@3156:       op->set_arg(i, arg);
never@3156:     }
never@3156:   }
never@3156: 
never@3156:   op->set_socket(s);
never@3156:   return op;
never@3156: }
never@3156: 
never@3156: 
never@3156: // Dequeue an operation
never@3156: //
never@3156: // In the Bsd implementation there is only a single operation and clients
never@3156: // cannot queue commands (except at the socket level).
never@3156: //
never@3156: BsdAttachOperation* BsdAttachListener::dequeue() {
never@3156:   for (;;) {
never@3156:     int s;
never@3156: 
never@3156:     // wait for client to connect
never@3156:     struct sockaddr addr;
never@3156:     socklen_t len = sizeof(addr);
never@3156:     RESTARTABLE(::accept(listener(), &addr, &len), s);
never@3156:     if (s == -1) {
never@3156:       return NULL;      // log a warning?
never@3156:     }
never@3156: 
never@3156:     // get the credentials of the peer and check the effective uid/guid
never@3156:     // - check with jeff on this.
never@3156:     uid_t puid;
never@3156:     gid_t pgid;
never@3156:     if (::getpeereid(s, &puid, &pgid) != 0) {
never@3156:       int res;
never@3156:       RESTARTABLE(::close(s), res);
never@3156:       continue;
never@3156:     }
never@3156:     uid_t euid = geteuid();
never@3156:     gid_t egid = getegid();
never@3156: 
never@3156:     if (puid != euid || pgid != egid) {
never@3156:       int res;
never@3156:       RESTARTABLE(::close(s), res);
never@3156:       continue;
never@3156:     }
never@3156: 
never@3156:     // peer credential look okay so we read the request
never@3156:     BsdAttachOperation* op = read_request(s);
never@3156:     if (op == NULL) {
never@3156:       int res;
never@3156:       RESTARTABLE(::close(s), res);
never@3156:       continue;
never@3156:     } else {
never@3156:       return op;
never@3156:     }
never@3156:   }
never@3156: }
never@3156: 
never@3156: // write the given buffer to the socket
never@3156: int BsdAttachListener::write_fully(int s, char* buf, int len) {
never@3156:   do {
never@3156:     int n = ::write(s, buf, len);
never@3156:     if (n == -1) {
never@3156:       if (errno != EINTR) return -1;
never@3156:     } else {
never@3156:       buf += n;
never@3156:       len -= n;
never@3156:     }
never@3156:   }
never@3156:   while (len > 0);
never@3156:   return 0;
never@3156: }
never@3156: 
never@3156: // Complete an operation by sending the operation result and any result
never@3156: // output to the client. At this time the socket is in blocking mode so
never@3156: // potentially we can block if there is a lot of data and the client is
never@3156: // non-responsive. For most operations this is a non-issue because the
never@3156: // default send buffer is sufficient to buffer everything. In the future
never@3156: // if there are operations that involves a very big reply then it the
never@3156: // socket could be made non-blocking and a timeout could be used.
never@3156: 
never@3156: void BsdAttachOperation::complete(jint result, bufferedStream* st) {
never@3156:   JavaThread* thread = JavaThread::current();
never@3156:   ThreadBlockInVM tbivm(thread);
never@3156: 
never@3156:   thread->set_suspend_equivalent();
never@3156:   // cleared by handle_special_suspend_equivalent_condition() or
never@3156:   // java_suspend_self() via check_and_wait_while_suspended()
never@3156: 
never@3156:   // write operation result
never@3156:   char msg[32];
never@3156:   sprintf(msg, "%d\n", result);
never@3156:   int rc = BsdAttachListener::write_fully(this->socket(), msg, strlen(msg));
never@3156: 
never@3156:   // write any result data
never@3156:   if (rc == 0) {
never@3156:     BsdAttachListener::write_fully(this->socket(), (char*) st->base(), st->size());
never@3156:     ::shutdown(this->socket(), 2);
never@3156:   }
never@3156: 
never@3156:   // done
never@3156:   RESTARTABLE(::close(this->socket()), rc);
never@3156: 
never@3156:   // were we externally suspended while we were waiting?
never@3156:   thread->check_and_wait_while_suspended();
never@3156: 
never@3156:   delete this;
never@3156: }
never@3156: 
never@3156: 
never@3156: // AttachListener functions
never@3156: 
never@3156: AttachOperation* AttachListener::dequeue() {
never@3156:   JavaThread* thread = JavaThread::current();
never@3156:   ThreadBlockInVM tbivm(thread);
never@3156: 
never@3156:   thread->set_suspend_equivalent();
never@3156:   // cleared by handle_special_suspend_equivalent_condition() or
never@3156:   // java_suspend_self() via check_and_wait_while_suspended()
never@3156: 
never@3156:   AttachOperation* op = BsdAttachListener::dequeue();
never@3156: 
never@3156:   // were we externally suspended while we were waiting?
never@3156:   thread->check_and_wait_while_suspended();
never@3156: 
never@3156:   return op;
never@3156: }
never@3156: 
never@3156: int AttachListener::pd_init() {
never@3156:   JavaThread* thread = JavaThread::current();
never@3156:   ThreadBlockInVM tbivm(thread);
never@3156: 
never@3156:   thread->set_suspend_equivalent();
never@3156:   // cleared by handle_special_suspend_equivalent_condition() or
never@3156:   // java_suspend_self() via check_and_wait_while_suspended()
never@3156: 
never@3156:   int ret_code = BsdAttachListener::init();
never@3156: 
never@3156:   // were we externally suspended while we were waiting?
never@3156:   thread->check_and_wait_while_suspended();
never@3156: 
never@3156:   return ret_code;
never@3156: }
never@3156: 
never@3156: // Attach Listener is started lazily except in the case when
never@3156: // +ReduseSignalUsage is used
never@3156: bool AttachListener::init_at_startup() {
never@3156:   if (ReduceSignalUsage) {
never@3156:     return true;
never@3156:   } else {
never@3156:     return false;
never@3156:   }
never@3156: }
never@3156: 
never@3156: // If the file .attach_pid<pid> exists in the working directory
never@3156: // or /tmp then this is the trigger to start the attach mechanism
never@3156: bool AttachListener::is_init_trigger() {
never@3156:   if (init_at_startup() || is_initialized()) {
never@3156:     return false;               // initialized at startup or already initialized
never@3156:   }
never@3156:   char path[PATH_MAX + 1];
never@3156:   int ret;
never@3156:   struct stat st;
never@3156: 
never@3156:   snprintf(path, PATH_MAX + 1, "%s/.attach_pid%d",
never@3156:            os::get_temp_directory(), os::current_process_id());
never@3156:   RESTARTABLE(::stat(path, &st), ret);
never@3156:   if (ret == 0) {
never@3156:     // simple check to avoid starting the attach mechanism when
never@3156:     // a bogus user creates the file
never@3156:     if (st.st_uid == geteuid()) {
never@3156:       init();
never@3156:       return true;
never@3156:     }
never@3156:   }
never@3156:   return false;
never@3156: }
never@3156: 
never@3156: // if VM aborts then remove listener
never@3156: void AttachListener::abort() {
never@3156:   listener_cleanup();
never@3156: }
never@3156: 
never@3156: void AttachListener::pd_data_dump() {
never@3156:   os::signal_notify(SIGQUIT);
never@3156: }
never@3156: 
never@3156: AttachOperationFunctionInfo* AttachListener::pd_find_operation(const char* n) {
never@3156:   return NULL;
never@3156: }
never@3156: 
never@3156: jint AttachListener::pd_set_flag(AttachOperation* op, outputStream* out) {
never@3156:   out->print_cr("flag '%s' cannot be changed", op->arg(0));
never@3156:   return JNI_ERR;
never@3156: }
never@3156: 
never@3156: void AttachListener::pd_detachall() {
never@3156:   // do nothing for now
never@3156: }