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SONARPY-1146 Rule S6329: Allowing public network access to cloud resources is security-sensitive - Implement for Instances related resources (#1246)
* SONARPY-1146 Rule S6329: Allowing public network access to cloud resources is security-sensitive - Implement for Instances related resources
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+302
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‎python-checks/src/main/java/org/sonar/python/checks/cdk/CdkPredicate.java

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@@ -122,6 +122,10 @@ public static Predicate<Expression> isListLiteral() {
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return expression -> expression.is(Tree.Kind.LIST_LITERAL);
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}
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public static Predicate<Expression> isSubscriptionExpression() {
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return expression -> expression.is(Tree.Kind.SUBSCRIPTION);
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}
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/**
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* @return Predicate which tests if expression is a string and starts with the expected value
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*/

‎python-checks/src/main/java/org/sonar/python/checks/cdk/PublicNetworkAccessToCloudResourcesCheck.java

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@@ -19,25 +19,43 @@
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*/
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package org.sonar.python.checks.cdk;
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import java.util.Collections;
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import java.util.Optional;
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import java.util.Set;
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import java.util.function.Predicate;
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import org.sonar.check.Rule;
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import org.sonar.plugins.python.api.SubscriptionContext;
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import org.sonar.plugins.python.api.tree.CallExpression;
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import org.sonar.plugins.python.api.tree.Expression;
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import org.sonar.plugins.python.api.tree.ListLiteral;
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import org.sonar.plugins.python.api.tree.QualifiedExpression;
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import org.sonar.plugins.python.api.tree.SubscriptionExpression;
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import org.sonar.plugins.python.api.tree.Tree;
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import org.sonar.python.tree.TreeUtils;
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import static org.sonar.python.checks.cdk.CdkPredicate.isCallExpression;
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import static org.sonar.python.checks.cdk.CdkPredicate.isFqn;
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import static org.sonar.python.checks.cdk.CdkPredicate.isFqnOf;
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import static org.sonar.python.checks.cdk.CdkPredicate.isListLiteral;
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import static org.sonar.python.checks.cdk.CdkPredicate.isSubscriptionExpression;
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import static org.sonar.python.checks.cdk.CdkPredicate.isTrue;
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import static org.sonar.python.checks.cdk.CdkUtils.ExpressionFlow;
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import static org.sonar.python.checks.cdk.CdkUtils.getArgument;
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import static org.sonar.python.checks.cdk.CdkUtils.getDictionary;
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import static org.sonar.python.checks.cdk.CdkUtils.getDictionaryPair;
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@Rule(key = "S6329")
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public class PublicNetworkAccessToCloudResourcesCheck extends AbstractCdkResourceCheck {
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public static final String PUBLICLY_ACCESSIBLE_ARG_NAME = "publicly_accessible";
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private static final String SUBNET_TYPE = "subnet_type";
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private static final String ASSOCIATE_PUBLIC_IP_ADDRESS = "associate_public_ip_address";
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private static final String MESSAGE = "Make sure allowing public network access is safe here.";
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private static final String SENSITIVE_SUBNET = "aws_cdk.aws_ec2.SubnetType.PUBLIC";
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private static final Set<String> SAFE_SUBNET_TYPES = Set.of("ISOLATED", "PRIVATE_ISOLATED", "PRIVATE", "PRIVATE_WITH_NAT");
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public static final String PUBLICLY_ACCESSIBLE_ARG_NAME = "publicly_accessible";
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private static final Set<String> COMPLIANT_SUBNETS =
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Set.of("aws_cdk.aws_ec2.SubnetType.PRIVATE_ISOLATED", "aws_cdk.aws_ec2.SubnetType.PRIVATE_WITH_EGRESS", "aws_cdk.aws_ec2.SubnetType.PRIVATE_WITH_NAT");
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@Override
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protected void registerFqnConsumer() {
@@ -55,6 +73,152 @@ protected void registerFqnConsumer() {
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argument -> argument.addIssueIf(isTrue(), MESSAGE)
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)
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);
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checkFqn("aws_cdk.aws_ec2.Instance", PublicNetworkAccessToCloudResourcesCheck::checkInstance);
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checkFqn("aws_cdk.aws_ec2.CfnInstance", PublicNetworkAccessToCloudResourcesCheck::checkCfnInstance);
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}
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/**
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* Check that a CallExpression (supposedly an aws_cdk.aws_ec2.Instance() call) has a sensitive 'vpc_subnets' argument
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* <pre>aws_cdk.aws_ec2.Instance(vpc_subnets=ec2.SubnetSelection(subnet_type=ec2.SubnetType.PUBLIC))</pre>
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*/
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private static void checkInstance(SubscriptionContext ctx, CallExpression callExpression) {
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getArgument(ctx, callExpression, "vpc_subnets")
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.ifPresent(flow -> {
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checkVpcSubnetAsSensitiveSubnetSelectionCall(ctx, flow);
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checkVpcSubnetAsSensitiveDictionary(ctx, flow);
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});
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}
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/**
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* Check that the provided ExpressionFlow lead to a sensitive CallExpression of aws_cdk.aws_ec2.SubnetSelection
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* <pre>aws_cdk.aws_ec2.SubnetSelection(subnet_type=aws_cdk.aws_ec2.SubnetType.PUBLIC)</pre>
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*/
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private static void checkVpcSubnetAsSensitiveSubnetSelectionCall(SubscriptionContext ctx, CdkUtils.ExpressionFlow flow) {
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flow.getExpression(isFqn("aws_cdk.aws_ec2.SubnetSelection"))
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.filter(expression -> expression.is(Tree.Kind.CALL_EXPR)).map(CallExpression.class::cast)
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.ifPresent(callExpression ->
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getArgument(ctx, callExpression, SUBNET_TYPE)
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.flatMap(flowArg -> flowArg.getExpression(isFqn(SENSITIVE_SUBNET)))
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.ifPresent(expr -> ctx.addIssue(callExpression.parent(), MESSAGE)));
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}
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/**
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* Check that the provided ExpressionFlow lead to a DictionaryLiteral with a sensitive 'subnet_type' attribute
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* <pre>{"subnet_type" : aws_cdk.aws_ec2.SubnetType.PUBLIC}}</pre>
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*/
110+
private static void checkVpcSubnetAsSensitiveDictionary(SubscriptionContext ctx, CdkUtils.ExpressionFlow flow) {
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getDictionary(flow)
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.flatMap(dictionary -> getDictionaryPair(ctx, dictionary, SUBNET_TYPE))
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.flatMap(element -> element.value.getExpression(isFqn(SENSITIVE_SUBNET)))
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.ifPresent(expression -> raiseIssueOnParent(ctx, expression, Tree.Kind.REGULAR_ARGUMENT));
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}
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/**
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* Check that a CallExpression (supposedly an aws_cdk.aws_ec2.checkCfnInstance() call) has a sensitive 'network_interfaces' argument.
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* Also check if a valid and compliant subnet_id is provided, in which case this CallExpression is not considered as sensitive.
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* <pre>
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* aws_cdk.aws_ec2.CfnInstance(network_interfaces=[aws_cdk.aws_ec2.CfnInstance.NetworkInterfaceProperty(associate_public_ip_address=True)]) # Sensitive
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* aws_cdk.aws_ec2.CfnInstance(network_interfaces=[{"associate_public_ip_address" : True}]) # Sensitive
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* aws_cdk.aws_ec2.CfnInstance(network_interfaces=[aws_cdk.aws_ec2.CfnInstance.NetworkInterfaceProperty(associate_public_ip_address=True,
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* subnet_id=aws_cdk.aws_ec2.Vpc.select_subnets(subnet_type=aws_cdk.aws_ec2.SubnetType.PRIVATE_ISOLATED).subnet_ids[0])]) # Compliant
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* aws_cdk.aws_ec2.CfnInstance(network_interfaces=[{"associate_public_ip_address" : True,
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* "subnet_id" : aws_cdk.aws_ec2.Vpc.select_subnets(subnet_type=aws_cdk.aws_ec2.SubnetType.PRIVATE_ISOLATED).subnet_ids[0]}]) # Compliant
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* </pre>
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*/
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private static void checkCfnInstance(SubscriptionContext ctx, CallExpression callExpression) {
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getArgument(ctx, callExpression, "network_interfaces")
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.flatMap(flow -> flow.getExpression(isListLiteral())).map(ListLiteral.class::cast)
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.map(listLiteral -> listLiteral.elements().expressions())
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.orElse(Collections.emptyList())
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.forEach(expression -> {
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checkNetworkInterfacesCallExpression(ctx, expression);
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checkNetworkInterfacesDictionary(ctx, expression);
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});
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}
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/**
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* Check that the provided ExpressionFlow lead to a sensitive CallExpression of aws_cdk.aws_ec2.CfnInstance.NetworkInterfaceProperty
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* <pre>
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* aws_cdk.aws_ec2.CfnInstance.NetworkInterfaceProperty(associate_public_ip_address=True) # Sensitive
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* aws_cdk.aws_ec2.CfnInstance.NetworkInterfaceProperty(associate_public_ip_address=True,
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* subnet_id=aws_cdk.aws_ec2.Vpc.select_subnets(subnet_type=aws_cdk.aws_ec2.SubnetType.PRIVATE_ISOLATED).subnet_ids[0])] # Compliant
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* </pre>
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*/
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private static void checkNetworkInterfacesCallExpression(SubscriptionContext ctx, Expression expression) {
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Optional.of(expression)
150+
.filter(isCallExpression()).map(CallExpression.class::cast)
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.filter(isFqn("aws_cdk.aws_ec2.CfnInstance.NetworkInterfaceProperty"))
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.ifPresent(call -> checkSensitiveOptionWithoutCompliantSubnetDefined(ctx, call));
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}
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private static void checkSensitiveOptionWithoutCompliantSubnetDefined(SubscriptionContext ctx, CallExpression callExpression) {
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Optional<CdkUtils.ExpressionFlow> associatedPublicIpAddress = getArgument(ctx, callExpression, ASSOCIATE_PUBLIC_IP_ADDRESS);
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Optional<CdkUtils.ExpressionFlow> subnetId = getArgument(ctx, callExpression, "subnet_id");
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159+
if (associatedPublicIpAddress.filter(flow -> flow.hasExpression(isTrue())).isPresent()
160+
&& subnetId.filter(PublicNetworkAccessToCloudResourcesCheck::hasPrivateSubnetDefined).isEmpty()) {
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associatedPublicIpAddress.get().addIssue(MESSAGE);
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}
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}
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/**
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* Check that the provided ExpressionFlow lead to a DictionaryLiteral with a sensitive associate_public_ip_address/subnet_id
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* <pre>
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* {"associate_public_ip_address" : True} # Sensitive
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* {"associate_public_ip_address" : True, "subnet_id" : ec2.Vpc.select_subnets(subnet_type=ec2.SubnetType.PRIVATE_ISOLATED).subnet_ids[0]} #Compliant
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* </pre>
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*/
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private static void checkNetworkInterfacesDictionary(SubscriptionContext ctx, Expression expression) {
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getDictionary(expression)
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.map(dictionaryLiteral -> UnrestrictedAdministrationCheckPartCfnSecurity.DictionaryAsMap.build(ctx, dictionaryLiteral))
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.ifPresent(dictionaryAsMap -> {
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if (dictionaryAsMap.hasKeyValuePair(ASSOCIATE_PUBLIC_IP_ADDRESS, isTrue())
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&& dictionaryAsMap.getValue("subnet_id").filter(PublicNetworkAccessToCloudResourcesCheck::hasPrivateSubnetDefined).isEmpty()) {
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dictionaryAsMap.getKeyString(ASSOCIATE_PUBLIC_IP_ADDRESS).ifPresent(expr -> raiseIssueOnParent(ctx, expr, Tree.Kind.KEY_VALUE_PAIR));
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}
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});
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}
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/**
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* Check that the provided ExpressionFlow has a compliant (private subnet_type) CallExpression over aws_cdk.aws_ec2.Vpc.select_subnets() method.
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* <pre>aws_cdk.aws_ec2.Vpc.select_subnets(subnet_type=ec2.SubnetType.PRIVATE_ISOLATED).subnet_ids[0]</pre>
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*/
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private static boolean hasPrivateSubnetDefined(CdkUtils.ExpressionFlow subnetId) {
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return subnetId.getExpression(isSubscriptionExpression())
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.map(SubscriptionExpression.class::cast).map(SubscriptionExpression::object)
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.filter(PublicNetworkAccessToCloudResourcesCheck::isCompliantSubnet)
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.isPresent();
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}
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private static boolean isCompliantSubnet(Expression expression) {
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Optional<CallExpression> callExpression = getCallSelectSubnets(expression);
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return callExpression
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.flatMap(call -> getArgument(null, call, SUBNET_TYPE))
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.filter(flow -> flow.hasExpression(isFqnOf(COMPLIANT_SUBNETS)))
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.isPresent();
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}
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private static Optional<CallExpression> getCallSelectSubnets(Expression expression) {
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if (expression.is(Tree.Kind.QUALIFIED_EXPR)) {
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Expression qualifier = ((QualifiedExpression) expression).qualifier();
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CdkUtils.ExpressionFlow flow = CdkUtils.ExpressionFlow.build(null, qualifier);
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return flow.getExpression(isCallExpression().and(isFqn("aws_cdk.aws_ec2.Vpc.select_subnets")))
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.map(CallExpression.class::cast);
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}
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if (expression.is(Tree.Kind.NAME)) {
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CdkUtils.ExpressionFlow flow = CdkUtils.ExpressionFlow.build(null, expression);
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return flow.getExpression(isQualifiedExpression()).map(QualifiedExpression.class::cast)
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.map(qualifiedExpression -> CdkUtils.ExpressionFlow.build(null, qualifiedExpression.qualifier()))
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.flatMap(flow2 -> flow2.getExpression(isCallExpression().and(isFqn("aws_cdk.aws_ec2.Vpc.select_subnets"))))
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.map(CallExpression.class::cast);
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}
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return Optional.empty();
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}
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private static void raiseIssueOnParent(SubscriptionContext ctx, Expression expression, Tree.Kind kind) {
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ctx.addIssue(Optional.ofNullable(TreeUtils.firstAncestorOfKind(expression, kind)).orElse(expression), MESSAGE);
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}
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private static void checkDatabaseInstance(SubscriptionContext ctx, CallExpression call) {
@@ -63,7 +227,7 @@ private static void checkDatabaseInstance(SubscriptionContext ctx, CallExpressio
63227
Optional<ExpressionFlow> subnetType = vpcSubnets
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.flatMap(flow -> flow.getExpression(isCallExpression().and(isFqn("aws_cdk.aws_ec2.SubnetSelection"))))
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.map(CallExpression.class::cast)
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.flatMap(subnetSelection -> getArgument(ctx, subnetSelection, "subnet_type"));
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.flatMap(subnetSelection -> getArgument(ctx, subnetSelection, SUBNET_TYPE));
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68232
if (subnetType.filter(isSafeSubnetSelection()).isPresent()) {
69233
return;
@@ -86,7 +250,10 @@ private static Predicate<ExpressionFlow> isSafeSubnetSelection() {
86250
}
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private static Predicate<ExpressionFlow> isPublicSubnetSelection() {
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return subnetType -> subnetType.hasExpression(isFqn("aws_cdk.aws_ec2.SubnetType.PUBLIC"));
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return subnetType -> subnetType.hasExpression(isFqn(SENSITIVE_SUBNET));
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}
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private static Predicate<Expression> isQualifiedExpression() {
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return expression -> expression.is(Tree.Kind.QUALIFIED_EXPR);
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}
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}

‎python-checks/src/main/java/org/sonar/python/checks/cdk/UnrestrictedAdministrationCheckPartCfnSecurity.java

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@@ -158,6 +158,15 @@ public Optional<Expression> get(String key, Predicate<Expression> valuePredicate
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return map.get(key).value.getExpression(valuePredicate);
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}
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public Optional<Expression> getKeyString(String key) {
162+
return Optional.ofNullable(map.get(key))
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.flatMap(keyValuePair -> keyValuePair.key.getExpression(isStringLiteral()));
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}
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public Optional<CdkUtils.ExpressionFlow> getValue(String key) {
167+
return Optional.ofNullable(map.get(key)).map(keyValuePair -> keyValuePair.value);
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}
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public void addIssue(String key, String message) {
162171
if (map.containsKey(key)) {
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map.get(key).value.addIssue(message);

‎python-checks/src/test/java/org/sonar/python/checks/cdk/PublicNetworkAccessToCloudResourcesCheckTest.java

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@@ -36,4 +36,9 @@ public void testCfnMethod() {
3636
public void testDatabaseInstance() {
3737
PythonCheckVerifier.verify("src/test/resources/checks/cdk/publicNetworkAccessDatabaseInstance.py", check);
3838
}
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@Test
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public void testInstance() {
42+
PythonCheckVerifier.verify("src/test/resources/checks/cdk/publicNetworkAccessDatabaseMigration_Instance.py", check);
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}
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}

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