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3960
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1 /*
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2 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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20 * or visit www.oracle.com if you need additional information or have any
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21 * questions.
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22 *
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23 */
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24
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25 #include "precompiled.hpp"
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26 #include "runtime/interfaceSupport.hpp"
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27 #include "runtime/os.hpp"
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28 #include "services/attachListener.hpp"
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29 #include "services/dtraceAttacher.hpp"
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30
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31 #include <unistd.h>
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32 #include <signal.h>
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33 #include <sys/types.h>
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34 #include <sys/socket.h>
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35 #include <sys/un.h>
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36 #include <sys/stat.h>
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37
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38 #ifndef UNIX_PATH_MAX
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39 #define UNIX_PATH_MAX sizeof(((struct sockaddr_un *)0)->sun_path)
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40 #endif
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41
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42 // The attach mechanism on Bsd uses a UNIX domain socket. An attach listener
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43 // thread is created at startup or is created on-demand via a signal from
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44 // the client tool. The attach listener creates a socket and binds it to a file
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45 // in the filesystem. The attach listener then acts as a simple (single-
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46 // threaded) server - it waits for a client to connect, reads the request,
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47 // executes it, and returns the response to the client via the socket
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48 // connection.
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49 //
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50 // As the socket is a UNIX domain socket it means that only clients on the
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51 // local machine can connect. In addition there are two other aspects to
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52 // the security:
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53 // 1. The well known file that the socket is bound to has permission 400
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54 // 2. When a client connect, the SO_PEERCRED socket option is used to
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55 // obtain the credentials of client. We check that the effective uid
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56 // of the client matches this process.
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57
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58 // forward reference
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59 class BsdAttachOperation;
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60
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61 class BsdAttachListener: AllStatic {
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62 private:
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63 // the path to which we bind the UNIX domain socket
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64 static char _path[UNIX_PATH_MAX];
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65 static bool _has_path;
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66
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67 // the file descriptor for the listening socket
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68 static int _listener;
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69
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70 static void set_path(char* path) {
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71 if (path == NULL) {
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72 _has_path = false;
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73 } else {
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74 strncpy(_path, path, UNIX_PATH_MAX);
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75 _path[UNIX_PATH_MAX-1] = '\0';
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76 _has_path = true;
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77 }
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78 }
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79
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80 static void set_listener(int s) { _listener = s; }
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81
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82 // reads a request from the given connected socket
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83 static BsdAttachOperation* read_request(int s);
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84
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85 public:
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86 enum {
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87 ATTACH_PROTOCOL_VER = 1 // protocol version
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88 };
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89 enum {
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90 ATTACH_ERROR_BADVERSION = 101 // error codes
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91 };
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92
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93 // initialize the listener, returns 0 if okay
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94 static int init();
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95
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96 static char* path() { return _path; }
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97 static bool has_path() { return _has_path; }
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98 static int listener() { return _listener; }
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99
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100 // write the given buffer to a socket
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101 static int write_fully(int s, char* buf, int len);
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102
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103 static BsdAttachOperation* dequeue();
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104 };
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105
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106 class BsdAttachOperation: public AttachOperation {
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107 private:
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108 // the connection to the client
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109 int _socket;
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110
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111 public:
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112 void complete(jint res, bufferedStream* st);
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113
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114 void set_socket(int s) { _socket = s; }
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115 int socket() const { return _socket; }
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116
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117 BsdAttachOperation(char* name) : AttachOperation(name) {
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118 set_socket(-1);
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119 }
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120 };
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121
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122 // statics
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123 char BsdAttachListener::_path[UNIX_PATH_MAX];
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124 bool BsdAttachListener::_has_path;
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125 int BsdAttachListener::_listener = -1;
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126
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127 // Supporting class to help split a buffer into individual components
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128 class ArgumentIterator : public StackObj {
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129 private:
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130 char* _pos;
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131 char* _end;
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132 public:
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133 ArgumentIterator(char* arg_buffer, size_t arg_size) {
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134 _pos = arg_buffer;
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135 _end = _pos + arg_size - 1;
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136 }
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137 char* next() {
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138 if (*_pos == '\0') {
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139 return NULL;
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140 }
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141 char* res = _pos;
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142 char* next_pos = strchr(_pos, '\0');
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143 if (next_pos < _end) {
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144 next_pos++;
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145 }
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146 _pos = next_pos;
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147 return res;
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148 }
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149 };
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150
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151
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152 // atexit hook to stop listener and unlink the file that it is
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153 // bound too.
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154 extern "C" {
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155 static void listener_cleanup() {
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156 static int cleanup_done;
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157 if (!cleanup_done) {
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158 cleanup_done = 1;
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159 int s = BsdAttachListener::listener();
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160 if (s != -1) {
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161 ::close(s);
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162 }
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163 if (BsdAttachListener::has_path()) {
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164 ::unlink(BsdAttachListener::path());
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165 }
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166 }
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167 }
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168 }
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169
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170 // Initialization - create a listener socket and bind it to a file
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171
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172 int BsdAttachListener::init() {
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173 char path[UNIX_PATH_MAX]; // socket file
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174 char initial_path[UNIX_PATH_MAX]; // socket file during setup
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175 int listener; // listener socket (file descriptor)
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176
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177 // register function to cleanup
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178 ::atexit(listener_cleanup);
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179
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180 int n = snprintf(path, UNIX_PATH_MAX, "%s/.java_pid%d",
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181 os::get_temp_directory(), os::current_process_id());
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182 if (n < (int)UNIX_PATH_MAX) {
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183 n = snprintf(initial_path, UNIX_PATH_MAX, "%s.tmp", path);
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184 }
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185 if (n >= (int)UNIX_PATH_MAX) {
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186 return -1;
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187 }
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188
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189 // create the listener socket
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190 listener = ::socket(PF_UNIX, SOCK_STREAM, 0);
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191 if (listener == -1) {
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192 return -1;
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193 }
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194
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195 // bind socket
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196 struct sockaddr_un addr;
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197 addr.sun_family = AF_UNIX;
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198 strcpy(addr.sun_path, initial_path);
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199 ::unlink(initial_path);
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200 int res = ::bind(listener, (struct sockaddr*)&addr, sizeof(addr));
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201 if (res == -1) {
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202 RESTARTABLE(::close(listener), res);
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203 return -1;
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204 }
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205
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206 // put in listen mode, set permissions, and rename into place
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207 res = ::listen(listener, 5);
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208 if (res == 0) {
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209 RESTARTABLE(::chmod(initial_path, S_IREAD|S_IWRITE), res);
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210 if (res == 0) {
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211 res = ::rename(initial_path, path);
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212 }
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213 }
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214 if (res == -1) {
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215 RESTARTABLE(::close(listener), res);
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216 ::unlink(initial_path);
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217 return -1;
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218 }
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219 set_path(path);
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220 set_listener(listener);
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221
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222 return 0;
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223 }
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224
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225 // Given a socket that is connected to a peer we read the request and
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226 // create an AttachOperation. As the socket is blocking there is potential
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227 // for a denial-of-service if the peer does not response. However this happens
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228 // after the peer credentials have been checked and in the worst case it just
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229 // means that the attach listener thread is blocked.
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230 //
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231 BsdAttachOperation* BsdAttachListener::read_request(int s) {
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232 char ver_str[8];
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233 sprintf(ver_str, "%d", ATTACH_PROTOCOL_VER);
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234
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235 // The request is a sequence of strings so we first figure out the
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236 // expected count and the maximum possible length of the request.
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237 // The request is:
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238 // <ver>0<cmd>0<arg>0<arg>0<arg>0
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239 // where <ver> is the protocol version (1), <cmd> is the command
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240 // name ("load", "datadump", ...), and <arg> is an argument
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241 int expected_str_count = 2 + AttachOperation::arg_count_max;
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242 const int max_len = (sizeof(ver_str) + 1) + (AttachOperation::name_length_max + 1) +
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243 AttachOperation::arg_count_max*(AttachOperation::arg_length_max + 1);
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244
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245 char buf[max_len];
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246 int str_count = 0;
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247
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248 // Read until all (expected) strings have been read, the buffer is
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249 // full, or EOF.
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250
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251 int off = 0;
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252 int left = max_len;
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253
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254 do {
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255 int n;
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256 RESTARTABLE(read(s, buf+off, left), n);
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257 if (n == -1) {
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258 return NULL; // reset by peer or other error
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259 }
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260 if (n == 0) {
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261 break;
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262 }
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263 for (int i=0; i<n; i++) {
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264 if (buf[off+i] == 0) {
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265 // EOS found
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266 str_count++;
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267
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268 // The first string is <ver> so check it now to
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269 // check for protocol mis-match
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270 if (str_count == 1) {
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271 if ((strlen(buf) != strlen(ver_str)) ||
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272 (atoi(buf) != ATTACH_PROTOCOL_VER)) {
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273 char msg[32];
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274 sprintf(msg, "%d\n", ATTACH_ERROR_BADVERSION);
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275 write_fully(s, msg, strlen(msg));
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276 return NULL;
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277 }
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278 }
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279 }
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280 }
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281 off += n;
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282 left -= n;
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283 } while (left > 0 && str_count < expected_str_count);
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284
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285 if (str_count != expected_str_count) {
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286 return NULL; // incomplete request
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287 }
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288
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289 // parse request
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290
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291 ArgumentIterator args(buf, (max_len)-left);
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292
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293 // version already checked
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294 char* v = args.next();
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295
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296 char* name = args.next();
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297 if (name == NULL || strlen(name) > AttachOperation::name_length_max) {
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298 return NULL;
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299 }
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300
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301 BsdAttachOperation* op = new BsdAttachOperation(name);
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302
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303 for (int i=0; i<AttachOperation::arg_count_max; i++) {
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304 char* arg = args.next();
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305 if (arg == NULL) {
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306 op->set_arg(i, NULL);
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307 } else {
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308 if (strlen(arg) > AttachOperation::arg_length_max) {
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309 delete op;
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310 return NULL;
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311 }
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312 op->set_arg(i, arg);
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313 }
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314 }
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315
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316 op->set_socket(s);
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317 return op;
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318 }
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319
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320
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321 // Dequeue an operation
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322 //
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323 // In the Bsd implementation there is only a single operation and clients
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324 // cannot queue commands (except at the socket level).
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325 //
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326 BsdAttachOperation* BsdAttachListener::dequeue() {
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327 for (;;) {
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328 int s;
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329
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330 // wait for client to connect
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331 struct sockaddr addr;
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332 socklen_t len = sizeof(addr);
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333 RESTARTABLE(::accept(listener(), &addr, &len), s);
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334 if (s == -1) {
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335 return NULL; // log a warning?
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336 }
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337
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338 // get the credentials of the peer and check the effective uid/guid
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339 // - check with jeff on this.
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340 #ifdef _ALLBSD_SOURCE
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341 uid_t puid;
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342 gid_t pgid;
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343 if (::getpeereid(s, &puid, &pgid) != 0) {
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344 int res;
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345 RESTARTABLE(::close(s), res);
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346 continue;
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347 }
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348 #else
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349 struct ucred cred_info;
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350 socklen_t optlen = sizeof(cred_info);
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351 if (::getsockopt(s, SOL_SOCKET, SO_PEERCRED, (void*)&cred_info, &optlen) == -1) {
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352 int res;
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353 RESTARTABLE(::close(s), res);
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354 continue;
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355 }
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356 uid_t puid = cred_info.uid;
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357 gid_t pgid = cred_info.gid;
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358 #endif
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359 uid_t euid = geteuid();
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360 gid_t egid = getegid();
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361
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362 if (puid != euid || pgid != egid) {
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363 int res;
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364 RESTARTABLE(::close(s), res);
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365 continue;
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366 }
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367
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368 // peer credential look okay so we read the request
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369 BsdAttachOperation* op = read_request(s);
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370 if (op == NULL) {
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371 int res;
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372 RESTARTABLE(::close(s), res);
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373 continue;
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374 } else {
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375 return op;
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376 }
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377 }
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378 }
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379
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380 // write the given buffer to the socket
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381 int BsdAttachListener::write_fully(int s, char* buf, int len) {
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382 do {
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383 int n = ::write(s, buf, len);
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384 if (n == -1) {
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385 if (errno != EINTR) return -1;
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386 } else {
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387 buf += n;
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388 len -= n;
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389 }
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390 }
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391 while (len > 0);
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392 return 0;
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393 }
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394
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395 // Complete an operation by sending the operation result and any result
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396 // output to the client. At this time the socket is in blocking mode so
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397 // potentially we can block if there is a lot of data and the client is
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398 // non-responsive. For most operations this is a non-issue because the
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399 // default send buffer is sufficient to buffer everything. In the future
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400 // if there are operations that involves a very big reply then it the
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401 // socket could be made non-blocking and a timeout could be used.
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402
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403 void BsdAttachOperation::complete(jint result, bufferedStream* st) {
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404 JavaThread* thread = JavaThread::current();
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405 ThreadBlockInVM tbivm(thread);
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406
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407 thread->set_suspend_equivalent();
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408 // cleared by handle_special_suspend_equivalent_condition() or
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409 // java_suspend_self() via check_and_wait_while_suspended()
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410
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411 // write operation result
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412 char msg[32];
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413 sprintf(msg, "%d\n", result);
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414 int rc = BsdAttachListener::write_fully(this->socket(), msg, strlen(msg));
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415
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416 // write any result data
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417 if (rc == 0) {
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418 BsdAttachListener::write_fully(this->socket(), (char*) st->base(), st->size());
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419 ::shutdown(this->socket(), 2);
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420 }
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421
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422 // done
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423 RESTARTABLE(::close(this->socket()), rc);
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424
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425 // were we externally suspended while we were waiting?
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426 thread->check_and_wait_while_suspended();
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427
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428 delete this;
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429 }
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430
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431
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432 // AttachListener functions
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433
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434 AttachOperation* AttachListener::dequeue() {
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435 JavaThread* thread = JavaThread::current();
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436 ThreadBlockInVM tbivm(thread);
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437
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438 thread->set_suspend_equivalent();
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439 // cleared by handle_special_suspend_equivalent_condition() or
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440 // java_suspend_self() via check_and_wait_while_suspended()
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441
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442 AttachOperation* op = BsdAttachListener::dequeue();
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443
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444 // were we externally suspended while we were waiting?
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445 thread->check_and_wait_while_suspended();
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446
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447 return op;
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448 }
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449
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450 int AttachListener::pd_init() {
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451 JavaThread* thread = JavaThread::current();
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452 ThreadBlockInVM tbivm(thread);
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453
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454 thread->set_suspend_equivalent();
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455 // cleared by handle_special_suspend_equivalent_condition() or
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456 // java_suspend_self() via check_and_wait_while_suspended()
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457
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458 int ret_code = BsdAttachListener::init();
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459
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460 // were we externally suspended while we were waiting?
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461 thread->check_and_wait_while_suspended();
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462
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463 return ret_code;
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464 }
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465
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466 // Attach Listener is started lazily except in the case when
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467 // +ReduseSignalUsage is used
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468 bool AttachListener::init_at_startup() {
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469 if (ReduceSignalUsage) {
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470 return true;
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471 } else {
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472 return false;
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473 }
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474 }
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475
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476 // If the file .attach_pid<pid> exists in the working directory
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477 // or /tmp then this is the trigger to start the attach mechanism
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478 bool AttachListener::is_init_trigger() {
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479 if (init_at_startup() || is_initialized()) {
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480 return false; // initialized at startup or already initialized
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481 }
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482 char path[PATH_MAX + 1];
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483 int ret;
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484 struct stat st;
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485
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486 snprintf(path, PATH_MAX + 1, "%s/.attach_pid%d",
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487 os::get_temp_directory(), os::current_process_id());
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488 RESTARTABLE(::stat(path, &st), ret);
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489 if (ret == 0) {
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|
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490 // simple check to avoid starting the attach mechanism when
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491 // a bogus user creates the file
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492 if (st.st_uid == geteuid()) {
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493 init();
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494 return true;
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|
|
495 }
|
|
|
496 }
|
|
|
497 return false;
|
|
|
498 }
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499
|
|
|
500 // if VM aborts then remove listener
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|
|
501 void AttachListener::abort() {
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|
|
502 listener_cleanup();
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|
|
503 }
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504
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|
|
505 void AttachListener::pd_data_dump() {
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|
|
506 os::signal_notify(SIGQUIT);
|
|
|
507 }
|
|
|
508
|
|
|
509 AttachOperationFunctionInfo* AttachListener::pd_find_operation(const char* n) {
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|
|
510 return NULL;
|
|
|
511 }
|
|
|
512
|
|
|
513 jint AttachListener::pd_set_flag(AttachOperation* op, outputStream* out) {
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|
|
514 out->print_cr("flag '%s' cannot be changed", op->arg(0));
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|
|
515 return JNI_ERR;
|
|
|
516 }
|
|
|
517
|
|
|
518 void AttachListener::pd_detachall() {
|
|
|
519 // do nothing for now
|
|
|
520 }
|
