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Protection against Log4J 1.x CVEs #8

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Protection against Log4J 1.x CVEs #8

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c49e6a1
Protect against Log4J 1.x CVEs
sl-cloud-platform Dec 14, 2021
571266f
added SimpleSocketServer
sl-cloud-platform Dec 15, 2021
9008176
merged
sl-cloud-platform Dec 15, 2021
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141 changes: 117 additions & 24 deletions src/main/java/Log4jHotPatch.java
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Original file line number Diff line number Diff line change
Expand Up @@ -14,10 +14,7 @@
*/

import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.Instrumentation;
Expand All @@ -27,10 +24,6 @@
import java.security.ProtectionDomain;
import java.util.Properties;
import java.util.Set;
import java.util.jar.Attributes;
import java.util.jar.JarEntry;
import java.util.jar.JarOutputStream;
import java.util.jar.Manifest;

import com.sun.tools.attach.VirtualMachine;
import sun.jvmstat.monitor.MonitoredHost;
Expand All @@ -47,7 +40,7 @@
public class Log4jHotPatch {

// version of this agent
private static final int log4jFixerAgentVersion = 1;
private static final int log4jFixerAgentVersion = 2;

// property name for verbose flag
public static final String LOG4J_FIXER_VERBOSE = "log4jFixerVerbose";
Expand Down Expand Up @@ -111,20 +104,38 @@ public static void agentmain(String args, Instrumentation inst) {


ClassFileTransformer transformer = new ClassFileTransformer() {
public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
ProtectionDomain protectionDomain, byte[] classfileBuffer) {
if (className != null && className.endsWith("org/apache/logging/log4j/core/lookup/JndiLookup")) {
log("Transforming " + className + " (" + loader + ")");
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);
MethodInstrumentorClassVisitor cv = new MethodInstrumentorClassVisitor(asm, cw);
ClassReader cr = new ClassReader(classfileBuffer);
cr.accept(cv, 0);
return cw.toByteArray();
} else {
return null;
}
public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
ProtectionDomain protectionDomain, byte[] classfileBuffer) {
if (className != null && className.endsWith("org/apache/logging/log4j/core/lookup/JndiLookup")) {
log("Transforming " + className + " (" + loader + ")");
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);
MethodInstrumentorClassVisitor cv = new MethodInstrumentorClassVisitor(asm, cw);
ClassReader cr = new ClassReader(classfileBuffer);
cr.accept(cv, 0);

return cw.toByteArray();
} else if (className != null && (className.endsWith("org/apache/log4j/net/SocketServer") || className.endsWith("org/apache/log4j/net/SimpleSocketServer"))) {
log("Transforming " + className + " (" + loader + ")");
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);
SocketServerMethodInstrumentorClassVisitor sscv = new SocketServerMethodInstrumentorClassVisitor(asm, cw);
ClassReader cr = new ClassReader(classfileBuffer);
cr.accept(sscv, 0);
return cw.toByteArray();
} else if (className != null && className.endsWith("org/apache/log4j/net/JMSAppender")) {
log("Transforming " + className + " (" + loader + ")");
ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);
JMSAppenderMethodInstrumentorClassVisitor jmcv = new JMSAppenderMethodInstrumentorClassVisitor(asm, cw);
ClassReader cr = new ClassReader(classfileBuffer);

cr.accept(jmcv, 0);
return cw.toByteArray();
} else {
return null;
}
};


}
};

if (!staticAgent) {
int patchesApplied = 0;
Expand All @@ -133,7 +144,11 @@ public byte[] transform(ClassLoader loader, String className, Class<?> classBein

for (Class<?> c : inst.getAllLoadedClasses()) {
String className = c.getName();
if (className.endsWith("org.apache.logging.log4j.core.lookup.JndiLookup")) {
if (className.endsWith("org.apache.logging.log4j.core.lookup.JndiLookup") ||
className.endsWith("org.apache.log4j.net.SocketServer") ||
className.endsWith("org.apache.log4j.net.SimpleSocketServer") ||
className.endsWith("org.apache.log4j.net.JMSAppender")
) {
log("Patching " + c + " (" + c.getClassLoader() + ")");
try {
inst.retransformClasses(c);
Expand Down Expand Up @@ -183,6 +198,84 @@ public MethodVisitor visitMethod(int access, String name, String desc, String si
}
}

static class SocketServerMethodInstrumentorClassVisitor extends ClassVisitor {
private int asm;

public SocketServerMethodInstrumentorClassVisitor(int asm, ClassVisitor cv) {
super(asm, cv);
this.asm = asm;
}

@Override
public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
MethodVisitor mv = cv.visitMethod(access, name, desc, signature, exceptions);
if ("init".equals(name) || "main".equals(name)) {
mv = new EmptyVoidMethodInstrumentorMethodVisitor(asm, mv);
}
return mv;
}
}

static class JMSAppenderMethodInstrumentorClassVisitor extends ClassVisitor {
private int asm;

public JMSAppenderMethodInstrumentorClassVisitor(int asm, ClassVisitor cv) {
super(asm, cv);
this.asm = asm;
}

@Override
public MethodVisitor visitMethod(int access, String name, String desc, String signature, String[] exceptions) {
MethodVisitor mv = cv.visitMethod(access, name, desc, signature, exceptions);
if ("activateOptions".equals(name) || "append".equals(name) || "close".equals(name)) {
mv = new EmptyVoidMethodInstrumentorMethodVisitor(asm, mv);
} else if ("lookup".equals(name)) {
mv = new EmptyObjectMethodInstrumentorMethodVisitor(asm, mv);
} else if ("checkEntryConditions".equals(name)) {
mv = new EmptyBooleanMethodInstrumentorMethodVisitor(asm, mv);
}
return mv;
}
}

static class EmptyVoidMethodInstrumentorMethodVisitor extends MethodVisitor implements Opcodes {

public EmptyVoidMethodInstrumentorMethodVisitor(int asm, MethodVisitor mv) {
super(asm, mv);
}

@Override
public void visitCode() {
mv.visitInsn(RETURN);
}
}

static class EmptyObjectMethodInstrumentorMethodVisitor extends MethodVisitor implements Opcodes {

public EmptyObjectMethodInstrumentorMethodVisitor(int asm, MethodVisitor mv) {
super(asm, mv);
}

@Override
public void visitCode() {
mv.visitInsn(ACONST_NULL);
mv.visitInsn(ARETURN);
}
}

static class EmptyBooleanMethodInstrumentorMethodVisitor extends MethodVisitor implements Opcodes {

public EmptyBooleanMethodInstrumentorMethodVisitor(int asm, MethodVisitor mv) {
super(asm, mv);
}

@Override
public void visitCode() {
mv.visitInsn(ICONST_1);
mv.visitInsn(IRETURN);
}
}

static class MethodInstrumentorMethodVisitor extends MethodVisitor implements Opcodes {

public MethodInstrumentorMethodVisitor(int asm, MethodVisitor mv) {
Expand Down Expand Up @@ -253,8 +346,8 @@ private static boolean loadInstrumentationAgent(String[] pids) throws Exception
private static String getUID(String pid) {
try {
return Files.lines(FileSystems.getDefault().getPath("/proc/" + pid + "/status")).
filter(l -> l.startsWith("Uid:")).
findFirst().get().split("\\s")[1];
filter(l -> l.startsWith("Uid:")).
findFirst().get().split("\\s")[1];
} catch (Exception e) {
return null;
}
Expand Down