[JENKINS-18403] More reliable way of enforcing maximum bytecode versi…

…on on a remoting channel.
jenkinsci · Jul 10, 2013 · 09f20f1 · 09f20f1
1 parent f906bbf
commit 09f20f1
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Showing 2 changed files with 37 additions and 1 deletion.
diff --git a/src/main/java/hudson/remoting/Channel.java b/src/main/java/hudson/remoting/Channel.java
@@ -28,7 +28,6 @@
 import hudson.remoting.ExportTable.ExportList;
 import hudson.remoting.PipeWindow.Key;
 import hudson.remoting.PipeWindow.Real;
-import hudson.remoting.RemoteClassLoader.IClassLoader;
 import hudson.remoting.forward.ListeningPort;
 import hudson.remoting.forward.ForwarderFactory;
 import hudson.remoting.forward.PortForwarder;
@@ -289,6 +288,8 @@ protected int[] initialValue() {
 
     /*package*/ final JarLoaderImpl jarLoader;
 
+    short maximumBytecodeLevel = Short.MAX_VALUE;
+
     /**
      * Communication mode used in conjunction with {@link ClassicCommandTransport}.
      * 
@@ -860,6 +861,33 @@ public void setRestricted(boolean b) {
         isRestricted = b;
     }
 
+    /**
+     * Sets the maximum bytecode version (~ JDK) that we expect this channel to be able to load.
+     * If attempts are made to load remote classes using newer bytecode, they are immediately rejected,
+     * even if the remote JVM is actually new enough to load it.
+     * This helps maintain compatibility by making tests fail immediately without the need for an old JDK installation.
+     * By default, the remote class loader will try to load any bytecode version.
+     * @param level e.g. 5 for JDK 5 (the minimum sensible value)
+     * @since 2.29
+     */
+    public void setMaximumBytecodeLevel(short level) throws IOException, InterruptedException {
+        if (level < 5) {
+            throw new IllegalArgumentException("Does not make sense to specify JDK 1.4 or below since remoting itself requires JDK 5+");
+        }
+        call(new SetMaximumBytecodeLevel(level));
+    }
+    private static final class SetMaximumBytecodeLevel implements Callable<Void,RuntimeException> {
+        private static final long serialVersionUID = 1;
+        private final short level;
+        SetMaximumBytecodeLevel(short level) {
+            this.level = level;
+        }
+        public Void call() throws RuntimeException {
+            Channel.current().maximumBytecodeLevel = level;
+            return null;
+        }
+    }
+
     /**
      * Waits for this {@link Channel} to be closed down, but only up the given milliseconds.
      *

diff --git a/src/main/java/hudson/remoting/RemoteClassLoader.java b/src/main/java/hudson/remoting/RemoteClassLoader.java
@@ -279,6 +279,14 @@ private static Object _getClassLoadingLock(RemoteClassLoader rcl, String name) {
     static boolean TESTING;
 
     private Class<?> loadClassFile(String name, byte[] bytes) {
+        if (bytes.length < 8) {
+            throw new ClassFormatError(name + " is <8 bytes long");
+        }
+        short bytecodeLevel = (short) ((bytes[6] << 8) + (bytes[7] & 0xFF) - 44);
+        if (bytecodeLevel > channel.maximumBytecodeLevel) {
+            throw new ClassFormatError("this channel is restricted to JDK 1." + channel.maximumBytecodeLevel + " compatibility but " + name + " was compiled for 1." + bytecodeLevel);
+        }
+
         // if someone else is forcing us to load a class by giving as bytecode,
         // discard our prefetched version since we'll never use them.
         prefetchedClasses.remove(name);