Blame SOURCES/0001-Backport-fix-for-CVE-2017-5645.patch

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From ea4609eca531916ac347686c048bebdb7b4b6e0d Mon Sep 17 00:00:00 2001
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From: Michael Simacek <msimacek@redhat.com>
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Date: Fri, 2 Jun 2017 14:37:35 +0200
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Subject: [PATCH] Backport fix for CVE-2017-5645
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---
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 .../apache/log4j/FilteredObjectInputStream.java    | 65 ++++++++++++++++++++++
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 src/main/java/org/apache/log4j/net/SocketNode.java | 17 +++++-
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 2 files changed, 80 insertions(+), 2 deletions(-)
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 create mode 100644 src/main/java/org/apache/log4j/FilteredObjectInputStream.java
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diff --git a/src/main/java/org/apache/log4j/FilteredObjectInputStream.java b/src/main/java/org/apache/log4j/FilteredObjectInputStream.java
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new file mode 100644
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index 0000000..b9ef20c
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--- /dev/null
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+++ b/src/main/java/org/apache/log4j/FilteredObjectInputStream.java
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@@ -0,0 +1,65 @@
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+/*
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+ * Licensed to the Apache Software Foundation (ASF) under one or more
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+ * contributor license agreements. See the NOTICE file distributed with
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+ * this work for additional information regarding copyright ownership.
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+ * The ASF licenses this file to You under the Apache license, Version 2.0
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+ * (the "License"); you may not use this file except in compliance with
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+ * the License. You may obtain a copy of the License at
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+ *
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+ *      http://www.apache.org/licenses/LICENSE-2.0
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+ *
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+ * Unless required by applicable law or agreed to in writing, software
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+ * distributed under the License is distributed on an "AS IS" BASIS,
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+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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+ * See the license for the specific language governing permissions and
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+ * limitations under the license.
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+ */
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+package org.apache.log4j;
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+
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+import java.io.FileOutputStream;
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+import java.io.IOException;
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+import java.io.InputStream;
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+import java.io.InvalidObjectException;
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+import java.io.ObjectInputStream;
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+import java.io.ObjectStreamClass;
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+import java.util.Arrays;
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+import java.util.Collection;
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+import java.util.List;
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+
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+/**
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+ * Extended ObjectInputStream that only allows certain classes to be deserialized.
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+ *
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+ * Backported from 2.8.2
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+ */
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+public class FilteredObjectInputStream extends ObjectInputStream {
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+
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+    private static final List REQUIRED_JAVA_CLASSES = Arrays.asList(new String[] {
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+        // Types of non-trainsient fields of LoggingEvent
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+        "java.lang.String",
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+        "java.util.Hashtable",
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+        // ThrowableInformation
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+        "[Ljava.lang.String;"
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+    });
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+
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+    private final Collection allowedClasses;
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+
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+    public FilteredObjectInputStream(final InputStream in, final Collection allowedClasses) throws IOException {
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+        super(in);
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+        this.allowedClasses = allowedClasses;
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+    }
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+
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+    protected Class resolveClass(final ObjectStreamClass desc) throws IOException, ClassNotFoundException {
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+        String name = desc.getName();
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+        if (!(isAllowedByDefault(name) || allowedClasses.contains(name))) {
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+            throw new InvalidObjectException("Class is not allowed for deserialization: " + name);
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+        }
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+        return super.resolveClass(desc);
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+    }
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+
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+    private static boolean isAllowedByDefault(final String name) {
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+        return name.startsWith("org.apache.log4j.") ||
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+            name.startsWith("[Lorg.apache.log4j.") ||
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+            REQUIRED_JAVA_CLASSES.contains(name);
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+    }
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+
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+}
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diff --git a/src/main/java/org/apache/log4j/net/SocketNode.java b/src/main/java/org/apache/log4j/net/SocketNode.java
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index e977f13..f95bb10 100644
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--- a/src/main/java/org/apache/log4j/net/SocketNode.java
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+++ b/src/main/java/org/apache/log4j/net/SocketNode.java
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@@ -22,6 +22,10 @@ import java.io.IOException;
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 import java.io.InterruptedIOException;
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 import java.io.ObjectInputStream;
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 import java.net.Socket;
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+import java.util.ArrayList;
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+import java.util.Arrays;
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+import java.util.Collection;
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+import org.apache.log4j.FilteredObjectInputStream;
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 import org.apache.log4j.Logger;
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 import org.apache.log4j.spi.LoggerRepository;
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@@ -53,8 +57,9 @@ public class SocketNode implements Runnable {
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     this.socket = socket;
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     this.hierarchy = hierarchy;
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     try {
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-      ois = new ObjectInputStream(
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-                         new BufferedInputStream(socket.getInputStream()));
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+      ois = new FilteredObjectInputStream(
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+                         new BufferedInputStream(socket.getInputStream()),
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+                         getAllowedClasses());
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     } catch(InterruptedIOException e) {
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       Thread.currentThread().interrupt();
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       logger.error("Could not open ObjectInputStream to "+socket, e);
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@@ -65,6 +70,14 @@ public class SocketNode implements Runnable {
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     }
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   }
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+  private Collection getAllowedClasses() {
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+      Collection allowedClasses = new ArrayList();
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+      String property = System.getProperty("org.apache.log4j.net.allowedClasses");
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+      if (property != null)
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+          allowedClasses.addAll(Arrays.asList(property.split(",")));
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+      return allowedClasses;
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+  }
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+
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   //public
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   //void finalize() {
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   //System.err.println("-------------------------Finalize called");
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-- 
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2.9.4
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