[Java知识库]spring cloud gateway漏洞修改前后代码对比

修改部分：对于3.0.4版本和3.0.7版本主要修改是org.springframework.cloud.gateway.supportShortcutConfigurable类中的

static Object getValue(SpelExpressionParser parser, BeanFactory beanFactory, String entryValue) {
		Object value;
		String rawValue = entryValue;
		if (rawValue != null) {
			rawValue = rawValue.trim();
		}
		if (rawValue != null && rawValue.startsWith("#{") && entryValue.endsWith("}")) {
			// assume it's spel
			GatewayEvaluationContext context = new GatewayEvaluationContext(beanFactory);
			Expression expression = parser.parseExpression(entryValue, new TemplateParserContext());
			value = expression.getValue(context);
		}
		else {
			value = entryValue;
		}
		return value;
	}

此处的GatewayEvaluationContext context = new GatewayEvaluationContext(beanFactory);之前使用的

			StandardEvaluationContext context = new StandardEvaluationContext();
			context.setBeanResolver(new BeanFactoryResolver(beanFactory));

GatewayEvaluationContext 实际上是对SimpleEvaluationContext的一个包装真实动作都是由SimpleEvaluationContext执行的并通过添加一个配置属性来决定是否启用属性的处理

spring.cloud.gateway.restrictive-property-accessor.enabled

默认是true即不允许访问

最后原因在于

StandardEvaluationContext类的TypeLocator使用StandardTypeLocator类，此类处理spel的时候会从java.lang包下搜索需要的类并执行其方法及参数

例子如下代码

package com.example.demo;

import org.springframework.expression.EvaluationContext;
import org.springframework.expression.Expression;
import org.springframework.expression.common.TemplateParserContext;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.expression.spel.support.SimpleEvaluationContext;
import org.springframework.expression.spel.support.StandardEvaluationContext;

public class HelloTest {
    public static void main(String[] args) {
        
//        EvaluationContext standardEvaluationContext = SimpleEvaluationContext.forReadOnlyDataBinding().build();
        EvaluationContext standardEvaluationContext = new StandardEvaluationContext();
        SpelExpressionParser spelExpressionParser = new SpelExpressionParser();
        Expression expression = spelExpressionParser.parseExpression("#{T(java.lang.Runtime).getRuntime().exec(\"calc\")}", new TemplateParserContext());
        expression.getValue(standardEvaluationContext);

    }
}