Add support for CRIU unprivileged mode

dev/com.ibm.ws.kernel.boot.ws-server/publish/bin/server

@@ -30,6 +30,15 @@
 #TODO need to reflect this to criu checkpoint
 #                  Set to 1-4 with 4 being max verbosity. Two "2" is the default.
 #
+# CRIU_UNPRIVILEGED - Use criu in unprivileged mode.
+#                     Set to one of true, True, TRUE, 1
+#                     or false, False, FALSE, 0 to continue
+#                     to use criu in privileged mode.
+#
+# CRIU_EXTRA_ARGS   - Pass extra arguments to `criu restore`. Extra arguments are
+#                     appended to the end of the list of arguments and can therefore
+#                     override existing arguments, if desired.
+#
 # PID_DIR    - The directory that should be used for server pid file(s).
 #              The default value is ${WLP_OUTPUT_DIR}/.pid
 #
@@ -296,6 +305,36 @@ if [ -n "${WLP_SKIP_BOOTSTRAP_AGENT}" ]; then
   JAVA_AGENT_QUOTED=
 fi
 
+##
+## Determine if CRIU supports unprivileged mode.
+## Determine which CRIU mode to use, based on current euid, whether or not criu supports unprivileged mode, and the value of the CRIU_UNPRIVILEGED env var.
+## Set DO_CRIU_UNPRIVILEGED based on the above.
+##
+checkCriuUnprivileged()
+{
+  if [ -n "$CRIU_UNPRIVILEGED" ]; then
+    if [ "${CRIU_UNPRIVILEGED}" = "true" -o "${CRIU_UNPRIVILEGED}" = "1" -o "${CRIU_UNPRIVILEGED}" = "TRUE" -o "${CRIU_UNPRIVILEGED}" = "True" ]; then
+      # Use unprivileged if explicitly requested; if CRIU doesn't support it we'll hit an error later that will be shown to the user
+      DO_CRIU_UNPRIVILEGED=true
+    else
+      DO_CRIU_UNPRIVILEGED=false
+    fi
+    return
+  fi
+
+  # Determine if CRIU supports unprivileged mode
+  criu --help | grep -q -e '--unprivileged' && CRIU_SUPPORTS_UNPRIVILEGED=true || CRIU_SUPPORTS_UNPRIVILEGED=false
+
+  # Determine which CRIU mode to use, based on current euid and value of CRIU_SUPPORTS_UNPRIVILEGED
+  DO_CRIU_UNPRIVILEGED=false
+  if [ "$(id -u)" != 0 ]; then
+    # Not root, unprivileged by default if CRIU supports it
+    if [ $CRIU_SUPPORTS_UNPRIVILEGED = true ]; then
+      DO_CRIU_UNPRIVILEGED=true
+    fi
+  fi
+}
+
 ##
 ## createServer: Function to launch server create
 ##
@@ -932,6 +971,11 @@ javaCmd()
     fi
 
     JVM_OPTIONS_QUOTED="$JVM_OPTIONS_QUOTED -XX:+EnableCRIUSupport $X_WLP_IMMUTABLE_VARS"
+
+    checkCriuUnprivileged
+    if [ $DO_CRIU_UNPRIVILEGED = true ]; then
+      JVM_OPTIONS_QUOTED="$JVM_OPTIONS_QUOTED -Dio.openliberty.checkpoint.criu.unprivileged=true"
+    fi
   fi
 
 
@@ -1293,13 +1337,18 @@ criuRestore()
     CRIU_LOG_LEVEL=2
   fi  
 
+  checkCriuUnprivileged
+  if [ $DO_CRIU_UNPRIVILEGED = true ]; then
+    CRIU_EXTRA_ARGS="--unprivileged $CRIU_EXTRA_ARGS"
+  fi
+
   if $BACKGROUND_RESTORE
   then
     mkdirs "${X_PID_DIR}"
     rmIfExist "${X_PID_FILE}"
     criu restore --cpu-cap=none --file-locks --tcp-established --images-dir=${SERVER_OUTPUT_DIR}/workarea/checkpoint/image \
       --shell-job --verbosity=${CRIU_LOG_LEVEL} --log-file ${X_LOG_DIR}/checkpoint/restore.log --pidfile ${X_PID_FILE} \
-      --restore-detached 
+      --restore-detached ${CRIU_EXTRA_ARGS}
     rc=$?
     PID=`cat ${X_PID_FILE}`
     if [ $rc = 0 ]; then
@@ -1326,7 +1375,7 @@ criuRestore()
     trap "killIfRunning $TAIL_PID" EXIT
 
     criu restore --cpu-cap=none --file-locks --tcp-established --images-dir=${SERVER_OUTPUT_DIR}/workarea/checkpoint/image \
-      --shell-job --verbosity=${CRIU_LOG_LEVEL} --log-file ${X_LOG_DIR}/checkpoint/restore.log
+      --shell-job --verbosity=${CRIU_LOG_LEVEL} --log-file ${X_LOG_DIR}/checkpoint/restore.log ${CRIU_EXTRA_ARGS}
     rc=$?
 
     kill $TAIL_PID

dev/io.openliberty.checkpoint/src/io/openliberty/checkpoint/internal/CheckpointImpl.java

@@ -71,6 +71,7 @@
 public class CheckpointImpl implements RuntimeUpdateListener, ServerReadyStatus {
 
     private static final String CHECKPOINT_STUB_CRIU = "io.openliberty.checkpoint.stub.criu";
+    private static final String CHECKPOINT_CRIU_UNPRIVILEGED = "io.openliberty.checkpoint.criu.unprivileged";
     static final String HOOKS_REF_NAME_SINGLE_THREAD = "hooksSingleThread";
     static final String HOOKS_REF_NAME_MULTI_THREAD = "hooksMultiThread";
     private static final String DIR_CHECKPOINT = "checkpoint/";
@@ -110,7 +111,7 @@ public CheckpointImpl(ComponentContext cc, @Reference WsLocationAdmin locAdmin,
              */
             this.criu = new ExecuteCRIU() {
                 @Override
-                public void dump(Runnable prepare, Runnable restore, File imageDir, String logFileName, File workDir, File envProps) throws CheckpointFailedException {
+                public void dump(Runnable prepare, Runnable restore, File imageDir, String logFileName, File workDir, File envProps, boolean unprivileged) throws CheckpointFailedException {
                     prepare.run();
                     restore.run();
                 }
@@ -236,14 +237,16 @@ void checkpoint() throws CheckpointFailedException {
                 debug(tc, () -> "ExecuteCRIU service does not support checkpoint: " + cpfe.getMessage());
                 throw cpfe;
             }
+            boolean unprivileged = Boolean.valueOf(cc.getBundleContext().getProperty(CHECKPOINT_CRIU_UNPRIVILEGED));
             File imageDir = getImageDir();
             debug(tc, () -> "criu attempt dump to '" + imageDir + "' and exit process.");
 
             criu.dump(() -> prepare(singleThreadPrepareHooks),
                       () -> restore(singleThreadRestoreHooks),
                       imageDir, CHECKPOINT_LOG_FILE,
                       getLogsCheckpoint(),
-                      getEnvProperties());
+                      getEnvProperties(),
+                      unprivileged);
 
             debug(tc, () -> "criu dumped to " + imageDir + ", now in recovered process.");
         } catch (Exception e) {

dev/io.openliberty.checkpoint/src/io/openliberty/checkpoint/internal/criu/ExecuteCRIU.java

@@ -24,9 +24,10 @@ public interface ExecuteCRIU {
      * @param logFileName
      * @param workDir
      * @param envProps
+     * @param unprivileged
      * @throws CheckpointFailedException
      */
-    default void dump(Runnable prepare, Runnable restore, File imageDir, String logFileName, File workDir, File envProps) throws CheckpointFailedException {
+    default void dump(Runnable prepare, Runnable restore, File imageDir, String logFileName, File workDir, File envProps, boolean unprivileged) throws CheckpointFailedException {
         // do nothing
     };
 

dev/io.openliberty.checkpoint/src/io/openliberty/checkpoint/internal/openj9/ExecuteCRIU_OpenJ9.java

@@ -28,7 +28,7 @@ public class ExecuteCRIU_OpenJ9 implements ExecuteCRIU {
 
     @Override
     @FFDCIgnore({ JVMCheckpointException.class, SystemCheckpointException.class, RestoreException.class, JVMCRIUException.class, RuntimeException.class })
-    public void dump(Runnable prepare, Runnable restore, File imageDir, String logFileName, File workDir, File envProps) throws CheckpointFailedException {
+    public void dump(Runnable prepare, Runnable restore, File imageDir, String logFileName, File workDir, File envProps, boolean unprivileged) throws CheckpointFailedException {
         CRIUSupport criuSupport = new CRIUSupport(imageDir.toPath());
         criuSupport.registerPreSnapshotHook(prepare);
         criuSupport.registerPostRestoreHook(restore);
@@ -38,6 +38,13 @@ public void dump(Runnable prepare, Runnable restore, File imageDir, String logFi
         criuSupport.setWorkDir(workDir.toPath());
         criuSupport.setTCPEstablished(true);
         criuSupport.registerRestoreEnvFile(envProps.toPath());
+        if (unprivileged) {
+            try {
+                criuSupport.setUnprivileged(true);
+            } catch (NoSuchMethodError e) {
+                throw new CheckpointFailedException(Type.UNKNOWN, "JVM does not support CRIU unprivileged mode", e);
+            }
+        }
         try {
             criuSupport.checkpointJVM();
         } catch (JVMCheckpointException e) {

dev/io.openliberty.checkpoint/src/io/openliberty/checkpoint/internal/openj9/J9CRIUSupport.java

@@ -45,7 +45,7 @@ private static ExecuteCRIU createCRIUNotSupported(CheckpointFailedException.Type
         final CheckpointFailedException criuSupportException = new CheckpointFailedException(type, msg, null);
         return new ExecuteCRIU() {
             @Override
-            public void dump(Runnable prepare, Runnable restore, File imageDir, String logFileName, File workDir, File envProps) throws CheckpointFailedException {
+            public void dump(Runnable prepare, Runnable restore, File imageDir, String logFileName, File workDir, File envProps, boolean unprivileged) throws CheckpointFailedException {
                 throw criuSupportException;
             }
 

dev/io.openliberty.checkpoint/test/io/openliberty/checkpoint/internal/CheckpointImplTest.java

@@ -99,7 +99,8 @@ public TestCRIU() {
         }
 
         @Override
-        public void dump(Runnable prepare, Runnable restore, File imageDir, String logFileName, File workDir, File envProps) throws CheckpointFailedException {
+        public void dump(Runnable prepare, Runnable restore, File imageDir, String logFileName, File workDir, File envProps,
+                         boolean unprivileged) throws CheckpointFailedException {
             singleThreaded.set(true);
             try {
                 prepare.run();

dev/io.openliberty.org.eclipse.openj9.criu/src/org/eclipse/openj9/criu/CRIUSupport.java

@@ -214,6 +214,18 @@ public CRIUSupport setWorkDir(Path workDir) {
 		return this;
 	}
 
+	/**
+	 * Controls whether CRIU will be invoked in privileged or unprivileged mode.
+	 * <p>
+	 * Default: false
+	 *
+	 * @param unprivileged
+	 * @return this
+	 */
+	public CRIUSupport setUnprivileged(boolean unprivileged) {
+		return this;
+	}
+
 	/**
 	 * Append new environment variables to the set returned by ProcessEnvironment.getenv(...) upon
 	 * restore. All pre-existing (environment variables from checkpoint run) env