10: Create ExportedComponentsPlugin

src/main/java/com/bartek/esa/core/archetype/XmlPlugin.java

@@ -3,9 +3,16 @@ package com.bartek.esa.core.archetype;
 import com.bartek.esa.core.xml.XmlHelper;
 import com.bartek.esa.file.matcher.GlobMatcher;
 import org.w3c.dom.Document;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
 
 import javax.xml.namespace.QName;
 import java.io.File;
+import java.util.Arrays;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import static java.lang.String.format;
 
 public abstract class XmlPlugin extends BasePlugin {
     private final GlobMatcher globMatcher;
@@ -32,4 +39,21 @@ public abstract class XmlPlugin extends BasePlugin {
     protected Object xPath(Document xml, String expression, QName returnType) {
         return xmlHelper.xPath(xml, expression, returnType);
     }
+
+    protected Stream<Node> stream(NodeList nodeList) {
+        return xmlHelper.stream(nodeList);
+    }
+
+    protected String tagString(Node node) {
+        Node[] attributes = new Node[node.getAttributes().getLength()];
+        for(int i=0; i<attributes.length; ++i) {
+            attributes[i] = node.getAttributes().item(i);
+        }
+
+        String attributesString = Arrays.stream(attributes)
+                .map(n -> format("%s=\"%s\"", n.getNodeName(), n.getNodeValue()))
+                .collect(Collectors.joining(" "));
+
+        return format("<%s %s ...", node.getNodeName(), attributesString);
+    }
 }

src/main/java/com/bartek/esa/core/di/PluginModule.java

@@ -95,4 +95,10 @@ public class PluginModule {
     public Plugin suppressWarningsPlugin(GlobMatcher globMatcher, XmlHelper xmlHelper) {
         return new SuppressWarningsPlugin(globMatcher, xmlHelper);
     }
+
+    @Provides
+    @IntoSet
+    public Plugin exportedComponentsPlugin(GlobMatcher globMatcher, XmlHelper xmlHelper) {
+        return new ExportedComponentsPlugin(globMatcher, xmlHelper);
+    }
 }

src/main/java/com/bartek/esa/core/plugin/ExportedComponentsPlugin.java

@@ -0,0 +1,72 @@
+package com.bartek.esa.core.plugin;
+
+import com.bartek.esa.core.archetype.AndroidManifestPlugin;
+import com.bartek.esa.core.model.enumeration.Severity;
+import com.bartek.esa.core.xml.XmlHelper;
+import com.bartek.esa.file.matcher.GlobMatcher;
+import org.w3c.dom.Document;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+
+import javax.inject.Inject;
+import javax.xml.xpath.XPathConstants;
+import java.util.Optional;
+
+import static java.lang.String.format;
+
+public class ExportedComponentsPlugin extends AndroidManifestPlugin {
+
+    @Inject
+    public ExportedComponentsPlugin(GlobMatcher globMatcher, XmlHelper xmlHelper) {
+        super(globMatcher, xmlHelper);
+    }
+
+    @Override
+    protected void run(Document xml) {
+        findExportedComponents(xml, "activity");
+        findExportedComponents(xml, "service");
+        findExportedComponents(xml, "receiver");
+        findExportedProviders(xml);
+    }
+
+    private void findExportedComponents(Document xml, String component) {
+        NodeList exportedActivities = (NodeList) xPath(xml, format("/manifest/application/%s", component), XPathConstants.NODESET);
+        stream(exportedActivities)
+                .filter(this::isExported)
+                .filter(node -> doesNotHavePermission(node, "android:permission"))
+                .forEach(node -> addIssue(Severity.WARNING, format(".%s.NO_PERMISSION", component.toUpperCase()), null, tagString(node)));
+    }
+
+    private void findExportedProviders(Document xml) {
+        NodeList exportedProviders = (NodeList) xPath(xml, "/manifest/application/provider", XPathConstants.NODESET);
+        stream(exportedProviders)
+                .filter(this::isExported)
+                .filter(node -> doesNotHavePermission(node, "android:writePermission")
+                        || doesNotHavePermission(node, "android:readPermission"))
+                .forEach(node -> addIssue(Severity.WARNING, ".PROVIDER.NO_PERMISSION", null, tagString(node)));
+    }
+
+    private boolean doesNotHavePermission(Node node, String permissionAttribute) {
+        Boolean doesHavePermission = Optional.ofNullable(node.getAttributes().getNamedItem(permissionAttribute))
+                .map(Node::getNodeValue)
+                .map(s -> !s.isEmpty())
+                .orElse(false);
+        return !doesHavePermission;
+    }
+
+    private boolean isExported(Node node) {
+        return Optional.ofNullable(node.getAttributes().getNamedItem("android:exported"))
+                .map(Node::getNodeValue)
+                .map(v -> v.equals("true"))
+                .orElse(false);
+    }
+
+    private String nodeToString(Node node) {
+        String nodeName = Optional.ofNullable(node.getAttributes().getNamedItem("android:name"))
+                .map(Node::getNodeValue)
+                .map(name -> format(" android:name=\"%s\"", name))
+                .orElse("");
+
+        return format("<%s%s ...", node.getNodeName(), nodeName);
+    }
+}

src/main/java/com/bartek/esa/core/xml/XmlHelper.java

@@ -3,6 +3,8 @@ package com.bartek.esa.core.xml;
 import com.bartek.esa.error.EsaException;
 import io.vavr.control.Try;
 import org.w3c.dom.Document;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
 
 import javax.inject.Inject;
 import javax.xml.namespace.QName;
@@ -10,6 +12,8 @@ import javax.xml.parsers.DocumentBuilder;
 import javax.xml.parsers.DocumentBuilderFactory;
 import javax.xml.xpath.XPathFactory;
 import java.io.File;
+import java.util.Arrays;
+import java.util.stream.Stream;
 
 public class XmlHelper {
 
@@ -28,4 +32,13 @@ public class XmlHelper {
         return Try.of(() -> XPathFactory.newDefaultInstance().newXPath().evaluate(expression, xml, returnType))
                 .getOrElseThrow(EsaException::new);
     }
+
+    public Stream<Node> stream(NodeList nodeList) {
+        Node[] nodes = new Node[nodeList.getLength()];
+        for (int i=0; i<nodeList.getLength(); ++i) {
+            nodes[i] = nodeList.item(i);
+        }
+
+        return Arrays.stream(nodes);
+    }
 }

src/main/resources/description.properties

@@ -87,3 +87,23 @@ com.bartek.esa.core.plugin.ExternalStoragePlugin=External storage state is not c
 com.bartek.esa.core.plugin.SuppressWarningsPlugin=@SuppressWarnings annotation was found.\n\
   The @SuppressWarnings annotation might be hiding useful warnings.\n\
   Consider removing it.
+
+com.bartek.esa.core.plugin.ExportedComponentsPlugin.ACTIVITY.NO_PERMISSION=Exported activity.\n\
+  The activity is exported but not protected by any permission. \n\
+  It means any malicious application could make use of the component. \n\
+  Consider using 'android:permission' tag and adding custom permission to protect it.
+
+com.bartek.esa.core.plugin.ExportedComponentsPlugin.SERVICE.NO_PERMISSION=Exported service.\n\
+  The service is exported but not protected by any permission. \n\
+  It means any malicious application could make use of the component. \n\
+  Consider using 'android:permission' tag and adding custom permission to protect it.
+
+com.bartek.esa.core.plugin.ExportedComponentsPlugin.RECEIVER.NO_PERMISSION=Exported broadcast receiver.\n\
+  The broadcast receiver is exported but not protected by any permission. \n\
+  It means any malicious application could make use of the component. \n\
+  Consider using 'android:permission' tag and adding custom permission to protect it.
+
+com.bartek.esa.core.plugin.ExportedComponentsPlugin.PROVIDER.NO_PERMISSION=Exported content provider. Potential data leakage.\n\
+  The content provider is exported but not protected by any permissions. \n\
+  It means any malicious application could make use of data provided by the component and/or insert some new data. \n\
+  Consider using 'android:readPermission' and 'android:writePermission' tags and adding custom permission to protect it.