Talk about SecureHeadersGatewayFilter of spring cloud gateway.

  springcloud

Order

This paper mainly studies the SecureHeadersGatewayFilter of spring cloud gateway.

GatewayAutoConfiguration

@Configuration
@ConditionalOnProperty(name = "spring.cloud.gateway.enabled", matchIfMissing = true)
@EnableConfigurationProperties
@AutoConfigureBefore(HttpHandlerAutoConfiguration.class)
@AutoConfigureAfter({GatewayLoadBalancerClientAutoConfiguration.class, GatewayClassPathWarningAutoConfiguration.class})
@ConditionalOnClass(DispatcherHandler.class)
public class GatewayAutoConfiguration {
    //......
    @Bean
    public SecureHeadersGatewayFilterFactory secureHeadersGatewayFilterFactory(SecureHeadersProperties properties) {
        return new SecureHeadersGatewayFilterFactory(properties);
    }
    //......
}

SecureHeadersProperties

Configuration item

    {
      "sourceType": "org.springframework.cloud.gateway.filter.factory.SecureHeadersProperties",
      "defaultValue": "default-src 'self' https:; font-src 'self' https: data:; img-src 'self' https: data:; object-src 'none'; script-src https:; style-src 'self' https: 'unsafe-inline'",
      "name": "spring.cloud.gateway.filter.secure-headers.content-security-policy",
      "type": "java.lang.String"
    },
    {
      "sourceType": "org.springframework.cloud.gateway.filter.factory.SecureHeadersProperties",
      "defaultValue": "nosniff",
      "name": "spring.cloud.gateway.filter.secure-headers.content-type-options",
      "type": "java.lang.String"
    },
    {
      "sourceType": "org.springframework.cloud.gateway.filter.factory.SecureHeadersProperties",
      "defaultValue": "noopen",
      "name": "spring.cloud.gateway.filter.secure-headers.download-options",
      "type": "java.lang.String"
    },
    {
      "sourceType": "org.springframework.cloud.gateway.filter.factory.SecureHeadersProperties",
      "defaultValue": "DENY",
      "name": "spring.cloud.gateway.filter.secure-headers.frame-options",
      "type": "java.lang.String"
    },
    {
      "sourceType": "org.springframework.cloud.gateway.filter.factory.SecureHeadersProperties",
      "defaultValue": "none",
      "name": "spring.cloud.gateway.filter.secure-headers.permitted-cross-domain-policies",
      "type": "java.lang.String"
    },
    {
      "sourceType": "org.springframework.cloud.gateway.filter.factory.SecureHeadersProperties",
      "defaultValue": "no-referrer",
      "name": "spring.cloud.gateway.filter.secure-headers.referrer-policy",
      "type": "java.lang.String"
    },
    {
      "sourceType": "org.springframework.cloud.gateway.filter.factory.SecureHeadersProperties",
      "defaultValue": "max-age=631138519",
      "name": "spring.cloud.gateway.filter.secure-headers.strict-transport-security",
      "type": "java.lang.String"
    },
    {
      "sourceType": "org.springframework.cloud.gateway.filter.factory.SecureHeadersProperties",
      "defaultValue": "1 ; mode=block",
      "name": "spring.cloud.gateway.filter.secure-headers.xss-protection-header",
      "type": "java.lang.String"
    }

Entity class

spring-cloud-gateway-core-2.0.0.RC1-sources.jar! /org/springframework/cloud/gateway/filter/factory/SecureHeadersProperties.java

@ConfigurationProperties("spring.cloud.gateway.filter.secure-headers")
public class SecureHeadersProperties {
    public static final String X_XSS_PROTECTION_HEADER_DEFAULT = "1 ; mode=block";
    public static final String STRICT_TRANSPORT_SECURITY_HEADER_DEFAULT = "max-age=631138519"; //; includeSubDomains preload")
    public static final String X_FRAME_OPTIONS_HEADER_DEFAULT = "DENY"; //SAMEORIGIN = ALLOW-FROM
    public static final String X_CONTENT_TYPE_OPTIONS_HEADER_DEFAULT = "nosniff";
    public static final String REFERRER_POLICY_HEADER_DEFAULT = "no-referrer"; //no-referrer-when-downgrade = origin = origin-when-cross-origin = same-origin = strict-origin = strict-origin-when-cross-origin = unsafe-url
    public static final String CONTENT_SECURITY_POLICY_HEADER_DEFAULT = "default-src 'self' https:; font-src 'self' https: data:; img-src 'self' https: data:; object-src 'none'; script-src https:; style-src 'self' https: 'unsafe-inline'";
    public static final String X_DOWNLOAD_OPTIONS_HEADER_DEFAULT = "noopen";
    public static final String X_PERMITTED_CROSS_DOMAIN_POLICIES_HEADER_DEFAULT = "none";

    private String xssProtectionHeader = X_XSS_PROTECTION_HEADER_DEFAULT;
    private String strictTransportSecurity = STRICT_TRANSPORT_SECURITY_HEADER_DEFAULT;
    private String frameOptions = X_FRAME_OPTIONS_HEADER_DEFAULT;
    private String contentTypeOptions = X_CONTENT_TYPE_OPTIONS_HEADER_DEFAULT;
    private String referrerPolicy = REFERRER_POLICY_HEADER_DEFAULT;
    private String contentSecurityPolicy = CONTENT_SECURITY_POLICY_HEADER_DEFAULT;
    private String downloadOptions = X_DOWNLOAD_OPTIONS_HEADER_DEFAULT;
    private String permittedCrossDomainPolicies = X_PERMITTED_CROSS_DOMAIN_POLICIES_HEADER_DEFAULT;

    //......

    @Override
    public String toString() {
        final StringBuffer sb = new StringBuffer("SecureHeadersProperties{");
        sb.append("xssProtectionHeader='").append(xssProtectionHeader).append('\'');
        sb.append(", strictTransportSecurity='").append(strictTransportSecurity).append('\'');
        sb.append(", frameOptions='").append(frameOptions).append('\'');
        sb.append(", contentTypeOptions='").append(contentTypeOptions).append('\'');
        sb.append(", referrerPolicy='").append(referrerPolicy).append('\'');
        sb.append(", contentSecurityPolicy='").append(contentSecurityPolicy).append('\'');
        sb.append(", downloadOptions='").append(downloadOptions).append('\'');
        sb.append(", permittedCrossDomainPolicies='").append(permittedCrossDomainPolicies).append('\'');
        sb.append('}');
        return sb.toString();
    }
}

SecureHeadersGatewayFilterFactory

spring-cloud-gateway-core-2.0.0.RC1-sources.jar! /org/springframework/cloud/gateway/filter/factory/SecureHeadersGatewayFilterFactory.java

/**
 * https://blog.appcanary.com/2017/http-security-headers.html
 * @author Spencer Gibb
 */
public class SecureHeadersGatewayFilterFactory extends AbstractGatewayFilterFactory {

    public static final String X_XSS_PROTECTION_HEADER = "X-Xss-Protection";
    public static final String STRICT_TRANSPORT_SECURITY_HEADER = "Strict-Transport-Security";
    public static final String X_FRAME_OPTIONS_HEADER = "X-Frame-Options";
    public static final String X_CONTENT_TYPE_OPTIONS_HEADER = "X-Content-Type-Options";
    public static final String REFERRER_POLICY_HEADER = "Referrer-Policy";
    public static final String CONTENT_SECURITY_POLICY_HEADER = "Content-Security-Policy";
    public static final String X_DOWNLOAD_OPTIONS_HEADER = "X-Download-Options";
    public static final String X_PERMITTED_CROSS_DOMAIN_POLICIES_HEADER = "X-Permitted-Cross-Domain-Policies";

    private final SecureHeadersProperties properties;

    public SecureHeadersGatewayFilterFactory(SecureHeadersProperties properties) {
        this.properties = properties;
    }

    @Override
    public GatewayFilter apply(Object config) {
        //TODO: allow args to override properties

        return (exchange, chain) -> {
            HttpHeaders headers = exchange.getResponse().getHeaders();

            //TODO: allow header to be disabled
            headers.add(X_XSS_PROTECTION_HEADER, properties.getXssProtectionHeader());
            headers.add(STRICT_TRANSPORT_SECURITY_HEADER, properties.getStrictTransportSecurity());
            headers.add(X_FRAME_OPTIONS_HEADER, properties.getFrameOptions());
            headers.add(X_CONTENT_TYPE_OPTIONS_HEADER, properties.getContentTypeOptions());
            headers.add(REFERRER_POLICY_HEADER, properties.getReferrerPolicy());
            headers.add(CONTENT_SECURITY_POLICY_HEADER, properties.getContentSecurityPolicy());
            headers.add(X_DOWNLOAD_OPTIONS_HEADER, properties.getDownloadOptions());
            headers.add(X_PERMITTED_CROSS_DOMAIN_POLICIES_HEADER, properties.getPermittedCrossDomainPolicies());

            return chain.filter(exchange);
        };
    }
}

You can see that the filter adds a series of security-related headers to response headers.

Summary

SecureHeadersGatewayFilter added the following header to response

  • X-Xss-Protection

spring.cloud.gateway.filter.secure-headers.xss-protection-header=1 ; mode=block

  • Strict-Transport-Security

spring.cloud.gateway.filter.secure-headers.strict-transport-security=max-age=631138519

  • X-Frame-Options

spring.cloud.gateway.filter.secure-headers.frame-options=DENY

  • X-Content-Type-Options

spring.cloud.gateway.filter.secure-headers.content-type-options=nosniff

  • Referrer-Policy

spring.cloud.gateway.filter.secure-headers.referrer-policy=no-referrer

  • Content-Security-Policy

spring.cloud.gateway.filter.secure-headers.content-security-policy=default-src ‘self’ https:; font-src ‘self’ https: data:; img-src ‘self’ https: data:; object-src ‘none’; script-src https:; style-src ‘self’ https: ‘unsafe-inline’

  • X-Download-Options

spring.cloud.gateway.filter.secure-headers.download-options=noopen

  • X-Permitted-Cross-Domain-Policies

spring.cloud.gateway.filter.secure-headers.permitted-cross-domain-policies=none

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