Mercurial > hg > truffle
diff src/os/linux/vm/attachListener_linux.cpp @ 0:a61af66fc99e jdk7-b24
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author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
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children | 485d403e94e1 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/os/linux/vm/attachListener_linux.cpp Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,503 @@ +/* + * Copyright 2005-2006 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + */ + +# include "incls/_precompiled.incl" +# include "incls/_attachListener_linux.cpp.incl" + +#include <unistd.h> +#include <signal.h> +#include <sys/types.h> +#include <sys/socket.h> +#include <sys/un.h> +#include <sys/stat.h> + +// The attach mechanism on Linux 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 - tt 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 LinuxAttachOperation; + +class LinuxAttachListener: AllStatic { + private: + // the path to which we bind the UNIX domain socket + static char _path[PATH_MAX+1]; + 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, PATH_MAX); + _path[PATH_MAX] = '\0'; + _has_path = true; + } + } + + static void set_listener(int s) { _listener = s; } + + // reads a request from the given connected socket + static LinuxAttachOperation* 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 LinuxAttachOperation* dequeue(); +}; + +class LinuxAttachOperation: 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; } + + LinuxAttachOperation(char* name) : AttachOperation(name) { + set_socket(-1); + } +}; + +// statics +char LinuxAttachListener::_path[PATH_MAX+1]; +bool LinuxAttachListener::_has_path; +int LinuxAttachListener::_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 = LinuxAttachListener::listener(); + if (s != -1) { + ::close(s); + } + if (LinuxAttachListener::has_path()) { + ::unlink(LinuxAttachListener::path()); + } + } + } +} + +// Initialization - create a listener socket and bind it to a file + +int LinuxAttachListener::init() { + char path[PATH_MAX+1]; // socket file + int listener; // listener socket (file descriptor) + + // register function to cleanup + ::atexit(listener_cleanup); + + // create the listener socket + listener = ::socket(PF_UNIX, SOCK_STREAM, 0); + if (listener == -1) { + return -1; + } + + int res = -1; + struct sockaddr_un addr; + addr.sun_family = AF_UNIX; + + // FIXME: Prior to b39 the tool-side API expected to find the well + // known file in the working directory. To allow this libjvm.so work with + // a pre-b39 SDK we create it in the working directory if + // +StartAttachListener is used is used. All unit tests for this feature + // currently used this flag. Once b39 SDK has been promoted we can remove + // this code. + if (StartAttachListener) { + sprintf(path, ".java_pid%d", os::current_process_id()); + strcpy(addr.sun_path, path); + ::unlink(path); + res = ::bind(listener, (struct sockaddr*)&addr, sizeof(addr)); + } + if (res == -1) { + sprintf(path, "%s/.java_pid%d", os::get_temp_directory(), os::current_process_id()); + strcpy(addr.sun_path, path); + ::unlink(path); + res = ::bind(listener, (struct sockaddr*)&addr, sizeof(addr)); + } + if (res == -1) { + RESTARTABLE(::close(listener), res); + return -1; + } + set_path(path); + + // put in listen mode and set permission + if ((::listen(listener, 5) == -1) || (::chmod(path, S_IREAD|S_IWRITE) == -1)) { + RESTARTABLE(::close(listener), res); + ::unlink(path); + set_path(NULL); + return -1; + } + 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. +// +LinuxAttachOperation* LinuxAttachListener::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; + int max_len = (strlen(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; + } + + LinuxAttachOperation* op = new LinuxAttachOperation(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 Linux implementation there is only a single operation and clients +// cannot queue commands (except at the socket level). +// +LinuxAttachOperation* LinuxAttachListener::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. + 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 euid = geteuid(); + gid_t egid = getegid(); + + if (cred_info.uid != euid || cred_info.gid != egid) { + int res; + RESTARTABLE(::close(s), res); + continue; + } + + // peer credential look okay so we read the request + LinuxAttachOperation* 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 LinuxAttachListener::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 LinuxAttachOperation::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 = LinuxAttachListener::write_fully(this->socket(), msg, strlen(msg)); + + // write any result data + if (rc == 0) { + LinuxAttachListener::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 = LinuxAttachListener::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 = LinuxAttachListener::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 fn[32]; + sprintf(fn, ".attach_pid%d", os::current_process_id()); + int ret; + struct stat64 st; + RESTARTABLE(::stat64(fn, &st), ret); + if (ret == -1) { + sprintf(fn, "/tmp/.attach_pid%d", os::current_process_id()); + RESTARTABLE(::stat64(fn, &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 +}