解决WhiteListedAllowFromStrategy不生效问题

X-Frame-Options 有三个值:

DENY
表示该页面不允许在 frame 中展示，即便是在相同域名的页面中嵌套也不允许。
SAMEORIGIN
表示该页面可以在相同域名页面的 frame 中展示。
ALLOW-FROM uri
表示该页面可以在指定来源的 frame 中展示。

SpringSecurity对应的实现策略

image.png

WhiteListedAllowFromStrategy 不生效？

@EnableWebSecurity
@Configuration
public class WebSecurityConfig extends DefaultWebSecurityConfigurer {
    @Override
    public void configure(HttpSecurity http) throws Exception {

        super.configure(http);

        //disable 默认策略
        http.headers().frameOptions().disable();

        //允许同源
//        http.headers().frameOptions().sameOrigin();

        //指定单个域名
        //http.headers().addHeaderWriter(new XFrameOptionsHeaderWriter(new StaticAllowFromStrategy(new URI("https://cityradar.umeng.com"))));

        //域名白名单
        http.headers().addHeaderWriter(new XFrameOptionsHeaderWriter(
                new WhiteListedAllowFromStrategy(
                        Arrays.asList(
                                "https://a.test.com",
                                "https://b.test.com",
                                "https://c.test.com"
                        )
                )
        ));
    }

}

看了一下X-Frame-Options还是DENY，说明设置的白名单没有写入成功

源码分析

XFrameOptionsHeaderWriter负责写入header

public void writeHeaders(HttpServletRequest request, HttpServletResponse response) {
        if (XFrameOptionsHeaderWriter.XFrameOptionsMode.ALLOW_FROM.equals(this.frameOptionsMode)) {
            String allowFromValue = this.allowFromStrategy.getAllowFromValue(request);
            if (XFrameOptionsHeaderWriter.XFrameOptionsMode.DENY.getMode().equals(allowFromValue)) {
                response.setHeader("X-Frame-Options", XFrameOptionsHeaderWriter.XFrameOptionsMode.DENY.getMode());
            } else if (allowFromValue != null) {
                response.setHeader("X-Frame-Options", XFrameOptionsHeaderWriter.XFrameOptionsMode.ALLOW_FROM.getMode() + " " + allowFromValue);
            }
        } else {
            response.setHeader("X-Frame-Options", this.frameOptionsMode.getMode());
        }

    }

两个关键的地方：先获取allowFromValue，再设置header

1. String allowFromValue = this.allowFromStrategy.getAllowFromValue(request);

2. response.setHeader("X-Frame-Options", XFrameOptionsHeaderWriter.XFrameOptionsMode.ALLOW_FROM.getMode() + " " + allowFromValue);

allowFromValue如何获取

AbstractRequestParameterAllowFromStrategy中主要代码可以看出，是从request中的参数中获取，参数名默认是x-frames-allow-from

private String allowFromParameterName = "x-frames-allow-from";

    public String getAllowFromValue(HttpServletRequest request) {
        String allowFromOrigin = request.getParameter(this.allowFromParameterName);
        if (this.log.isDebugEnabled()) {
            this.log.debug("Supplied origin '" + allowFromOrigin + "'");
        }

        return StringUtils.hasText(allowFromOrigin) && this.allowed(allowFromOrigin) ? allowFromOrigin : "DENY";
    }

那岂不是可以随便传AllowFromValue了？注意这句

this.allowed(allowFromOrigin) ? allowFromOrigin : "DENY";

WhiteListedAllowFromStrategy策略中实现了此方法, 只有设置的AllowFromValue和白名单中的域名匹配上才会去设置

protected boolean allowed(String allowFromOrigin) {
        return this.allowed.contains(allowFromOrigin);
    }

总结：

要想使WhiteListedAllowFromStrategy生效，必须在请求参数中加上x-frames-allow-from参数，并且需要和WhiteListedAllowFromStrategy中设置的白名单匹配