[#2353] Use a privileged block to get ClassLoader and System property if needed

Motivation:
When using System.getProperty(...) and various methods to get a ClassLoader it will fail when a SecurityManager is in place.

Modifications:
Use a priveled block if needed. This work is based in the PR #2353 done by @anilsaldhana .

Result:
Code works also when SecurityManager is present

codec/src/main/java/io/netty/handler/codec/serialization/ClassResolvers.java

@@ -90,12 +90,12 @@ public final class ClassResolvers {
             return classLoader;
         }
 
-        final ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
+        final ClassLoader contextClassLoader = PlatformDependent.getContextClassLoader();
         if (contextClassLoader != null) {
             return contextClassLoader;
         }
 
-        return ClassResolvers.class.getClassLoader();
+        return PlatformDependent.getClassLoader(ClassResolvers.class);
     }
 
     private ClassResolvers() {

common/src/main/java/io/netty/util/Version.java

@@ -16,6 +16,8 @@
 
 package io.netty.util;
 
+import io.netty.util.internal.PlatformDependent;
+
 import java.io.InputStream;
 import java.net.URL;
 import java.text.ParseException;
@@ -61,7 +63,7 @@ public final class Version {
      */
     public static Map<String, Version> identify(ClassLoader classLoader) {
         if (classLoader == null) {
-            classLoader = Thread.currentThread().getContextClassLoader();
+            classLoader = PlatformDependent.getContextClassLoader();
         }
 
         // Collect all properties.

common/src/main/java/io/netty/util/internal/JavassistTypeParameterMatcherGenerator.java

@@ -51,9 +51,9 @@ public final class JavassistTypeParameterMatcherGenerator {
     }
 
     public static TypeParameterMatcher generate(Class<?> type) {
-        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
+        ClassLoader classLoader = PlatformDependent.getContextClassLoader();
         if (classLoader == null) {
-            classLoader = ClassLoader.getSystemClassLoader();
+            classLoader = PlatformDependent.getSystemClassLoader();
         }
         return generate(type, classLoader);
     }

common/src/main/java/io/netty/util/internal/PlatformDependent.java

@@ -387,10 +387,31 @@ public final class PlatformDependent {
         }
     }
 
+    /**
+     * Return the {@link ClassLoader} for the given {@link Class}.
+     */
+    public static ClassLoader getClassLoader(final Class<?> clazz) {
+        return PlatformDependent0.getClassLoader(clazz);
+    }
+
+    /**
+     * Return the context {@link ClassLoader} for the current {@link Thread}.
+     */
+    public static ClassLoader getContextClassLoader() {
+        return PlatformDependent0.getContextClassLoader();
+    }
+
+    /**
+     * Return the system {@link ClassLoader}.
+     */
+    public static ClassLoader getSystemClassLoader() {
+        return PlatformDependent0.getSystemClassLoader();
+    }
+
     private static boolean isAndroid0() {
         boolean android;
         try {
-            Class.forName("android.app.Application", false, ClassLoader.getSystemClassLoader());
+            Class.forName("android.app.Application", false, getSystemClassLoader());
             android = true;
         } catch (Exception e) {
             // Failed to load the class uniquely available in Android.
@@ -517,7 +538,7 @@ public final class PlatformDependent {
             }
 
             try {
-                Class.forName("java.time.Clock", false, Object.class.getClassLoader());
+                Class.forName("java.time.Clock", false, getClassLoader(Object.class));
                 javaVersion = 8;
                 break;
             } catch (Exception e) {
@@ -525,7 +546,7 @@ public final class PlatformDependent {
             }
 
             try {
-                Class.forName("java.util.concurrent.LinkedTransferQueue", false, BlockingQueue.class.getClassLoader());
+                Class.forName("java.util.concurrent.LinkedTransferQueue", false, getClassLoader(BlockingQueue.class));
                 javaVersion = 7;
                 break;
             } catch (Exception e) {
@@ -591,7 +612,7 @@ public final class PlatformDependent {
         long maxDirectMemory = 0;
         try {
             // Try to get from sun.misc.VM.maxDirectMemory() which should be most accurate.
-            Class<?> vmClass = Class.forName("sun.misc.VM", true, ClassLoader.getSystemClassLoader());
+            Class<?> vmClass = Class.forName("sun.misc.VM", true, getSystemClassLoader());
             Method m = vmClass.getDeclaredMethod("maxDirectMemory");
             maxDirectMemory = ((Number) m.invoke(null)).longValue();
         } catch (Throwable t) {
@@ -606,9 +627,9 @@ public final class PlatformDependent {
             // Now try to get the JVM option (-XX:MaxDirectMemorySize) and parse it.
             // Note that we are using reflection because Android doesn't have these classes.
             Class<?> mgmtFactoryClass = Class.forName(
-                    "java.lang.management.ManagementFactory", true, ClassLoader.getSystemClassLoader());
+                    "java.lang.management.ManagementFactory", true, getSystemClassLoader());
             Class<?> runtimeClass = Class.forName(
-                    "java.lang.management.RuntimeMXBean", true, ClassLoader.getSystemClassLoader());
+                    "java.lang.management.RuntimeMXBean", true, getSystemClassLoader());
 
             Object runtime = mgmtFactoryClass.getDeclaredMethod("getRuntimeMXBean").invoke(null);
 
@@ -662,7 +683,7 @@ public final class PlatformDependent {
         }
 
         try {
-            JavassistTypeParameterMatcherGenerator.generate(Object.class, PlatformDependent.class.getClassLoader());
+            JavassistTypeParameterMatcherGenerator.generate(Object.class, getClassLoader(PlatformDependent.class));
             logger.debug("Javassist: available");
             return true;
         } catch (Throwable t) {

common/src/main/java/io/netty/util/internal/PlatformDependent0.java

@@ -26,6 +26,8 @@ import java.lang.reflect.Method;
 import java.nio.Buffer;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
 import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
 import java.util.concurrent.atomic.AtomicLongFieldUpdater;
 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
@@ -50,7 +52,7 @@ final class PlatformDependent0 {
     static {
         boolean directBufferFreeable = false;
         try {
-            Class<?> cls = Class.forName("sun.nio.ch.DirectBuffer", false, PlatformDependent0.class.getClassLoader());
+            Class<?> cls = Class.forName("sun.nio.ch.DirectBuffer", false, getClassLoader(PlatformDependent0.class));
             Method method = cls.getMethod("cleaner");
             if ("sun.misc.Cleaner".equals(method.getReturnType().getName())) {
                 directBufferFreeable = true;
@@ -328,6 +330,45 @@ final class PlatformDependent0 {
         return new UnsafeAtomicLongFieldUpdater<T>(UNSAFE, tclass, fieldName);
     }
 
+    static ClassLoader getClassLoader(final Class<?> clazz) {
+        if (System.getSecurityManager() == null) {
+            return clazz.getClassLoader();
+        } else {
+            return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
+                @Override
+                public ClassLoader run() {
+                    return clazz.getClassLoader();
+                }
+            });
+        }
+    }
+
+    static ClassLoader getContextClassLoader() {
+        if (System.getSecurityManager() == null) {
+            return Thread.currentThread().getContextClassLoader();
+        } else {
+            return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
+                @Override
+                public ClassLoader run() {
+                    return Thread.currentThread().getContextClassLoader();
+                }
+            });
+        }
+    }
+
+    static ClassLoader getSystemClassLoader() {
+        if (System.getSecurityManager() == null) {
+            return ClassLoader.getSystemClassLoader();
+        } else {
+            return AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
+                @Override
+                public ClassLoader run() {
+                    return ClassLoader.getSystemClassLoader();
+                }
+            });
+        }
+    }
+
     private PlatformDependent0() {
     }
 

common/src/main/java/io/netty/util/internal/SystemPropertyUtil.java

@@ -18,6 +18,8 @@ package io.netty.util.internal;
 import io.netty.util.internal.logging.InternalLogger;
 import io.netty.util.internal.logging.InternalLoggerFactory;
 
+import java.security.AccessController;
+import java.security.PrivilegedAction;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
@@ -64,7 +66,7 @@ public final class SystemPropertyUtil {
      *         {@code def} if there's no such property or if an access to the
      *         specified property is not allowed.
      */
-    public static String get(String key, String def) {
+    public static String get(final String key, String def) {
         if (key == null) {
             throw new NullPointerException("key");
         }
@@ -74,7 +76,16 @@ public final class SystemPropertyUtil {
 
         String value = null;
         try {
-            value = System.getProperty(key);
+            if (System.getSecurityManager() == null) {
+                value = System.getProperty(key);
+            } else {
+                value = AccessController.doPrivileged(new PrivilegedAction<String>() {
+                    @Override
+                    public String run() {
+                        return System.getProperty(key);
+                    }
+                });
+            }
         } catch (Exception e) {
             if (!loggedException) {
                 log("Unable to retrieve a system property '" + key + "'; default values will be used.", e);

example/src/main/java/io/netty/example/http/file/HttpStaticFileServerHandler.java

@@ -34,6 +34,7 @@ import io.netty.handler.codec.http.HttpResponseStatus;
 import io.netty.handler.codec.http.LastHttpContent;
 import io.netty.handler.stream.ChunkedFile;
 import io.netty.util.CharsetUtil;
+import io.netty.util.internal.SystemPropertyUtil;
 
 import javax.activation.MimetypesFileTypeMap;
 import java.io.File;
@@ -264,7 +265,7 @@ public class HttpStaticFileServerHandler extends SimpleChannelInboundHandler<Ful
         }
 
         // Convert to absolute path.
-        return System.getProperty("user.dir") + File.separator + uri;
+        return SystemPropertyUtil.get("user.dir") + File.separator + uri;
     }
 
     private static final Pattern ALLOWED_FILE_NAME = Pattern.compile("[A-Za-z0-9][-_A-Za-z0-9\\.]*");

example/src/main/java/io/netty/example/http/websocketx/sslserver/WebSocketSslServer.java

@@ -20,6 +20,7 @@ import io.netty.channel.Channel;
 import io.netty.channel.EventLoopGroup;
 import io.netty.channel.nio.NioEventLoopGroup;
 import io.netty.channel.socket.nio.NioServerSocketChannel;
+import io.netty.util.internal.SystemPropertyUtil;
 
 /**
  * A HTTP server which serves Web Socket requests at:
@@ -74,13 +75,13 @@ public class WebSocketSslServer {
             port = 8443;
         }
 
-        String keyStoreFilePath = System.getProperty("keystore.file.path");
+        String keyStoreFilePath = SystemPropertyUtil.get("keystore.file.path");
         if (keyStoreFilePath == null || keyStoreFilePath.isEmpty()) {
             System.out.println("ERROR: System property keystore.file.path not set. Exiting now!");
             System.exit(1);
         }
 
-        String keyStoreFilePassword = System.getProperty("keystore.file.password");
+        String keyStoreFilePassword = SystemPropertyUtil.get("keystore.file.password");
         if (keyStoreFilePassword == null || keyStoreFilePassword.isEmpty()) {
             System.out.println("ERROR: System property keystore.file.password not set. Exiting now!");
             System.exit(1);

example/src/main/java/io/netty/example/http/websocketx/sslserver/WebSocketSslServerSslContext.java

@@ -15,6 +15,8 @@
  */
 package io.netty.example.http.websocketx.sslserver;
 
+import io.netty.util.internal.SystemPropertyUtil;
+
 import javax.net.ssl.KeyManagerFactory;
 import javax.net.ssl.SSLContext;
 import java.io.FileInputStream;
@@ -56,14 +58,14 @@ public final class WebSocketSslServerSslContext {
         SSLContext serverContext = null;
         try {
             // Key store (Server side certificate)
-            String algorithm = Security.getProperty("ssl.KeyManagerFactory.algorithm");
+            String algorithm = SystemPropertyUtil.get("ssl.KeyManagerFactory.algorithm");
             if (algorithm == null) {
                 algorithm = "SunX509";
             }
 
             try {
-                String keyStoreFilePath = System.getProperty("keystore.file.path");
+                String keyStoreFilePath = SystemPropertyUtil.get("keystore.file.path");
-                String keyStoreFilePassword = System.getProperty("keystore.file.password");
+                String keyStoreFilePassword = SystemPropertyUtil.get("keystore.file.password");
 
                 KeyStore ks = KeyStore.getInstance("JKS");
                 FileInputStream fin = new FileInputStream(keyStoreFilePath);

example/src/main/java/io/netty/example/securechat/SecureChatSslContextFactory.java

@@ -16,6 +16,7 @@
 package io.netty.example.securechat;
 
 import io.netty.handler.ssl.SslHandler;
+import io.netty.util.internal.SystemPropertyUtil;
 
 import java.security.KeyStore;
 import java.security.SecureRandom;
@@ -57,7 +58,7 @@ public final class SecureChatSslContextFactory {
     private static final SSLContext CLIENT_CONTEXT;
 
     static {
-        String algorithm = Security.getProperty("ssl.KeyManagerFactory.algorithm");
+        String algorithm = SystemPropertyUtil.get("ssl.KeyManagerFactory.algorithm");
         if (algorithm == null) {
             algorithm = "SunX509";
         }

handler/src/main/java/io/netty/handler/ssl/SslHandler.java

@@ -625,7 +625,7 @@ public class SslHandler extends ByteToMessageDecoder {
                     // No match by now.. Try to load the class via classloader and inspect it.
                     // This is mainly done as other JDK implementations may differ in name of
                     // the impl.
-                    Class<?> clazz = getClass().getClassLoader().loadClass(classname);
+                    Class<?> clazz = PlatformDependent.getClassLoader(getClass()).loadClass(classname);
 
                     if (SocketChannel.class.isAssignableFrom(clazz)
                             || DatagramChannel.class.isAssignableFrom(clazz)) {

transport-native-epoll/src/main/java/io/netty/channel/epoll/Native.java

@@ -19,6 +19,8 @@ package io.netty.channel.epoll;
 import io.netty.channel.DefaultFileRegion;
 import io.netty.channel.epoll.EpollChannelOutboundBuffer.AddressEntry;
 import io.netty.util.internal.NativeLibraryLoader;
+import io.netty.util.internal.PlatformDependent;
+import io.netty.util.internal.SystemPropertyUtil;
 
 import java.io.IOException;
 import java.net.Inet6Address;
@@ -37,11 +39,11 @@ final class Native {
             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, (byte) 0xff, (byte) 0xff };
 
     static {
-        String name = System.getProperty("os.name").toLowerCase(Locale.UK).trim();
+        String name = SystemPropertyUtil.get("os.name").toLowerCase(Locale.UK).trim();
         if (!name.startsWith("linux")) {
             throw new IllegalStateException("Only supported on Linux");
         }
-        NativeLibraryLoader.load("netty-transport-native-epoll", Native.class.getClassLoader());
+        NativeLibraryLoader.load("netty-transport-native-epoll", PlatformDependent.getClassLoader(Native.class));
     }
 
     // EventLoop operations and constants

transport/src/main/java/io/netty/channel/DefaultChannelId.java

@@ -302,7 +302,7 @@ final class DefaultChannelId implements ChannelId {
     }
 
     private static int defaultProcessId() {
-        final ClassLoader loader = ClassLoader.getSystemClassLoader();
+        final ClassLoader loader = PlatformDependent.getSystemClassLoader();
         String value;
         try {
             // Invoke java.lang.management.ManagementFactory.getRuntimeMXBean().getName()

transport/src/main/java/io/netty/channel/nio/NioEventLoop.java

@@ -67,7 +67,7 @@ public final class NioEventLoop extends SingleThreadEventLoop {
     static {
         String key = "sun.nio.ch.bugLevel";
         try {
-            String buglevel = System.getProperty(key);
+            String buglevel = SystemPropertyUtil.get(key);
             if (buglevel == null) {
                 System.setProperty(key, "");
             }
@@ -136,7 +136,7 @@ public final class NioEventLoop extends SingleThreadEventLoop {
             SelectedSelectionKeySet selectedKeySet = new SelectedSelectionKeySet();
 
             Class<?> selectorImplClass =
-                    Class.forName("sun.nio.ch.SelectorImpl", false, ClassLoader.getSystemClassLoader());
+                    Class.forName("sun.nio.ch.SelectorImpl", false, PlatformDependent.getSystemClassLoader());
 
             // Ensure the current selector implementation is what we can instrument.
             if (!selectorImplClass.isAssignableFrom(selector.getClass())) {

transport/src/main/java/io/netty/channel/socket/nio/NioDatagramChannelConfig.java

@@ -40,7 +40,7 @@ class NioDatagramChannelConfig extends DefaultDatagramChannelConfig {
     private static final Method SET_OPTION;
 
     static {
-        ClassLoader classLoader = DatagramChannel.class.getClassLoader();
+        ClassLoader classLoader = PlatformDependent.getClassLoader(DatagramChannel.class);
         Class<?> socketOptionType = null;
         try {
             socketOptionType = Class.forName("java.net.SocketOption", true, classLoader);