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/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.tools.lint.checks;
import static com.android.tools.lint.client.api.JavaParser.TYPE_STRING;
import com.android.annotations.NonNull;
import com.android.annotations.Nullable;
import com.android.tools.lint.client.api.JavaEvaluator;
import com.android.tools.lint.detector.api.Category;
import com.android.tools.lint.detector.api.Detector;
import com.android.tools.lint.detector.api.Detector.JavaPsiScanner;
import com.android.tools.lint.detector.api.Implementation;
import com.android.tools.lint.detector.api.Issue;
import com.android.tools.lint.detector.api.JavaContext;
import com.android.tools.lint.detector.api.LintUtils;
import com.android.tools.lint.detector.api.Location;
import com.android.tools.lint.detector.api.Scope;
import com.android.tools.lint.detector.api.Severity;
import com.intellij.psi.JavaRecursiveElementVisitor;
import com.intellij.psi.PsiClass;
import com.intellij.psi.PsiExpression;
import com.intellij.psi.PsiMethod;
import com.intellij.psi.PsiMethodCallExpression;
import com.intellij.psi.PsiReturnStatement;
import com.intellij.psi.PsiThrowStatement;
import java.util.Collections;
import java.util.List;
public class BadHostnameVerifierDetector extends Detector implements JavaPsiScanner {
@SuppressWarnings("unchecked")
private static final Implementation IMPLEMENTATION =
new Implementation(BadHostnameVerifierDetector.class,
Scope.JAVA_FILE_SCOPE);
public static final Issue ISSUE = Issue.create("BadHostnameVerifier",
"Insecure HostnameVerifier",
"This check looks for implementations of `HostnameVerifier` " +
"whose `verify` method always returns true (thus trusting any hostname) " +
"which could result in insecure network traffic caused by trusting arbitrary " +
"hostnames in TLS/SSL certificates presented by peers.",
Category.SECURITY,
6,
Severity.WARNING,
IMPLEMENTATION);
// ---- Implements JavaScanner ----
@Nullable
@Override
public List<String> applicableSuperClasses() {
return Collections.singletonList("javax.net.ssl.HostnameVerifier");
}
@Override
public void checkClass(@NonNull JavaContext context, @NonNull PsiClass declaration) {
JavaEvaluator evaluator = context.getEvaluator();
for (PsiMethod method : declaration.findMethodsByName("verify", false)) {
if (evaluator.methodMatches(method, null, false,
TYPE_STRING, "javax.net.ssl.SSLSession")) {
ComplexVisitor visitor = new ComplexVisitor(context);
declaration.accept(visitor);
if (visitor.isComplex()) {
return;
}
Location location = context.getNameLocation(method);
String message = String.format("`%1$s` always returns `true`, which " +
"could cause insecure network traffic due to trusting "
+ "TLS/SSL server certificates for wrong hostnames",
method.getName());
context.report(ISSUE, location, message);
break;
}
}
}
private static class ComplexVisitor extends JavaRecursiveElementVisitor {
@SuppressWarnings("unused")
private final JavaContext mContext;
private boolean mComplex;
public ComplexVisitor(JavaContext context) {
mContext = context;
}
@Override
public void visitThrowStatement(PsiThrowStatement statement) {
super.visitThrowStatement(statement);
mComplex = true;
}
@Override
public void visitMethodCallExpression(PsiMethodCallExpression expression) {
super.visitMethodCallExpression(expression);
// TODO: Ignore certain known safe methods, e.g. Logging etc
mComplex = true;
}
@Override
public void visitReturnStatement(PsiReturnStatement node) {
PsiExpression argument = node.getReturnValue();
if (argument != null) {
// TODO: Only do this if certain that there isn't some intermediate
// assignment, as exposed by the unit test
//Object value = ConstantEvaluator.evaluate(mContext, argument);
//if (Boolean.TRUE.equals(value)) {
if (LintUtils.isTrueLiteral(argument)) {
mComplex = false;
} else {
mComplex = true; // "return false" or some complicated logic
}
}
super.visitReturnStatement(node);
}
public boolean isComplex() {
return mComplex;
}
}
}