2 * Copyright 2016 Andrei Pangin
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
21 typedef HMODULE (WINAPI *GetModuleHandle_t)(LPCTSTR lpModuleName);
22 typedef FARPROC (WINAPI *GetProcAddress_t)(HMODULE hModule, LPCSTR lpProcName);
23 typedef int (__stdcall *JVM_EnqueueOperation_t)(char* cmd, char* arg0, char* arg1, char* arg2, char* pipename);
26 GetModuleHandle_t GetModuleHandleA;
27 GetProcAddress_t GetProcAddress;
30 char pipeName[MAX_PATH];
31 char args[4][MAX_PATH];
35 #pragma check_stack(off)
37 // This code is executed in remote JVM process; be careful with memory it accesses
38 DWORD WINAPI remote_thread_entry(LPVOID param) {
39 CallData* data = (CallData*)param;
41 HMODULE libJvm = data->GetModuleHandleA(data->strJvm);
43 JVM_EnqueueOperation_t JVM_EnqueueOperation = (JVM_EnqueueOperation_t)data->GetProcAddress(libJvm, data->strEnqueue);
44 if (JVM_EnqueueOperation != NULL) {
45 return (DWORD)JVM_EnqueueOperation(data->args[0], data->args[1], data->args[2], data->args[3], data->pipeName);
55 // Allocate executable memory in remote process
56 static LPTHREAD_START_ROUTINE allocate_code(HANDLE hProcess) {
57 SIZE_T codeSize = 1024;
58 LPVOID code = VirtualAllocEx(hProcess, NULL, codeSize, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
60 WriteProcessMemory(hProcess, code, remote_thread_entry, codeSize, NULL);
62 return (LPTHREAD_START_ROUTINE)code;
65 // Allocate memory for CallData in remote process
66 static LPVOID allocate_data(HANDLE hProcess, char* pipeName, int argc, char** argv) {
68 data.GetModuleHandleA = GetModuleHandleA;
69 data.GetProcAddress = GetProcAddress;
70 strcpy(data.strJvm, "jvm");
71 strcpy(data.strEnqueue, "JVM_EnqueueOperation");
72 strcpy(data.pipeName, pipeName);
75 for (i = 0; i < 4; i++) {
76 strcpy(data.args[i], i < argc ? argv[i] : "");
79 LPVOID remoteData = VirtualAllocEx(hProcess, NULL, sizeof(CallData), MEM_COMMIT, PAGE_READWRITE);
80 if (remoteData != NULL) {
81 WriteProcessMemory(hProcess, remoteData, &data, sizeof(data), NULL);
86 static void print_error(const char* msg, DWORD code) {
87 printf("%s (error code = %d)\n", msg, code);
90 // If the process is owned by another user, request SeDebugPrivilege to open it.
91 // Debug privileges are typically granted to Administrators.
92 static int enable_debug_privileges() {
94 if (!OpenThreadToken(GetCurrentThread(), TOKEN_ADJUST_PRIVILEGES, FALSE, &hToken)) {
95 if (!ImpersonateSelf(SecurityImpersonation) ||
96 !OpenThreadToken(GetCurrentThread(), TOKEN_ADJUST_PRIVILEGES, FALSE, &hToken)) {
102 if (!LookupPrivilegeValue(NULL, SE_DEBUG_NAME, &luid)) {
107 tp.PrivilegeCount = 1;
108 tp.Privileges[0].Luid = luid;
109 tp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
111 BOOL success = AdjustTokenPrivileges(hToken, FALSE, &tp, sizeof(tp), NULL, NULL);
113 return success ? 1 : 0;
116 // The idea of Dynamic Attach on Windows is to inject a thread into remote JVM
117 // that calls JVM_EnqueueOperation() function exported by HotSpot DLL
118 static int inject_thread(int pid, char* pipeName, int argc, char** argv) {
119 HANDLE hProcess = OpenProcess(PROCESS_ALL_ACCESS, FALSE, (DWORD)pid);
120 if (hProcess == NULL && GetLastError() == ERROR_ACCESS_DENIED) {
121 if (!enable_debug_privileges()) {
122 print_error("Not enough privileges", GetLastError());
125 hProcess = OpenProcess(PROCESS_ALL_ACCESS, FALSE, (DWORD)pid);
127 if (hProcess == NULL) {
128 print_error("Could not open process", GetLastError());
132 LPTHREAD_START_ROUTINE code = allocate_code(hProcess);
133 LPVOID data = code != NULL ? allocate_data(hProcess, pipeName, argc, argv) : NULL;
135 print_error("Could not allocate memory in target process", GetLastError());
136 CloseHandle(hProcess);
141 HANDLE hThread = CreateRemoteThread(hProcess, NULL, 0, code, data, 0, NULL);
142 if (hThread == NULL) {
143 print_error("Could not create remote thread", GetLastError());
146 printf("Connected to remote process\n");
147 WaitForSingleObject(hThread, INFINITE);
149 GetExitCodeThread(hThread, &exitCode);
151 print_error("Attach is not supported by the target process", exitCode);
154 CloseHandle(hThread);
157 VirtualFreeEx(hProcess, code, 0, MEM_RELEASE);
158 VirtualFreeEx(hProcess, data, 0, MEM_RELEASE);
159 CloseHandle(hProcess);
164 // JVM response is read from the pipe and mirrored to stdout
165 static int read_response(HANDLE hPipe) {
166 ConnectNamedPipe(hPipe, NULL);
170 if (!ReadFile(hPipe, buf, sizeof(buf) - 1, &bytesRead, NULL)) {
171 print_error("Error reading response", GetLastError());
175 // First line of response is the command result code
177 int result = atoi(buf);
180 fwrite(buf, 1, bytesRead, stdout);
181 } while (ReadFile(hPipe, buf, sizeof(buf), &bytesRead, NULL));
186 int main(int argc, char** argv) {
188 printf("jattach " JATTACH_VERSION " built on " __DATE__ "\n"
189 "Copyright 2018 Andrei Pangin\n"
191 "Usage: jattach <pid> <cmd> [args ...]\n");
195 int pid = atoi(argv[1]);
197 char pipeName[MAX_PATH];
198 sprintf(pipeName, "\\\\.\\pipe\\javatool%d", GetTickCount());
199 HANDLE hPipe = CreateNamedPipe(pipeName, PIPE_ACCESS_INBOUND, PIPE_TYPE_BYTE | PIPE_READMODE_BYTE | PIPE_WAIT,
200 1, 4096, 8192, NMPWAIT_USE_DEFAULT_WAIT, NULL);
202 print_error("Could not create pipe", GetLastError());
206 if (!inject_thread(pid, pipeName, argc - 2, argv + 2)) {
211 printf("Response code = ");
214 int result = read_response(hPipe);