Content-Security-Policy 允许站点管理者在指定的页面控制用户代理的资源。除了少数例外，这条政策将极大地指定服务源 以及脚本端点。这将帮助防止跨站脚本攻击（Cross-Site Script） (XSS).更多信息，请查阅 Content Security Policy (CSP).
| Header type | Response header |
|---|---|
| Forbidden header name | no |
概述
Content-Security-Policy: <policy-directive>; <policy-directive>
指令
取指令Fetch directives（其实叫源控制指令会更好一点）
通过取指令来控制某些可能被加载的资源类型的位置。
child-src- child-src：为 web workers和其他内嵌浏览器内容定义 合法的源，例如用
<frame>和<iframe>加载到页面的内容。 connect-src- connect-src：限制能通过脚本接口加载的URL。
default-src- default-src：为其他取指令提供备用服务fetch directives.
font-src- font-src：限制通过
@font-face加载的字体源。 frame-src- frame-src： 限制通过类似
<frame>和<iframe>标签加载的内嵌内容源。 img-src- img-src: 限制图片和图标源
manifest-src- manifest-src ： 限制 application manifest 文件源。
media-src- media-src：限制通过
<audio>或<video>标签加载的媒体文件源。 object-src- object-src：限制通过
<object>,<embed>，<applet>标签加载源。 script-src- script-src：限制javascript 源。
style-src- style-src：限制层叠样式表文件源。
worker-src- worker-src：限制
Worker,SharedWorker, 或者ServiceWorker脚本源。
文档指令Document directives
文档指令管理文档属性或者工作环境应用哪个策略。
base-uri- base-uri: 限制在DOM中使用base 标签 的URL
plugin-types- plugin-types: 限制一系列可以通过一些限制类型的资源加载内嵌到DOM的插件。
sandbox- sandbox: 允许类似{HTMLElement("iframe")}}
sandboxsandbox 属性， disown-opener- 确保资源在操作的时候能够脱离父页面。（windown.opener 对象）Ensures a resource will disown its opener when navigated to.
导航指令 Navigation directives
导航指令管理用户能打开的链接或者表单可提交的链接
form-action- 限制能被用来作为给定上下文的表单提交的 目标 URL （说白了，就是限制 form 的 action 属性的链接地址）
frame-ancestors- Specifies valid parents that may embed a page using
<frame>,<iframe>,<object>,<embed>, or<applet>. navigation-to- Restricts the URLs to which a document can navigate by any means (a, form, window.location, window.open, etc.)
Reporting directives
Reporting directives control the reporting process of CSP violations. See also the Content-Security-Policy-Report-Only header.
report-uri- Instructs the user agent to report attempts to violate the Content Security Policy. These violation reports consist of JSON documents sent via an HTTP
POSTrequest to the specified URI. report-to- Fires a
SecurityPolicyViolationEvent.
Other directives
block-all-mixed-content- Prevents loading any assets using HTTP when the page is loaded using HTTPS.
referrer- Used to specify information in the referer (sic) header for links away from a page. Use the
Referrer-Policyheader instead. require-sri-for- Requires the use of SRI for scripts or styles on the page.
upgrade-insecure-requests- Instructs user agents to treat all of a site's insecure URLs (those served over HTTP) as though they have been replaced with secure URLs (those served over HTTPS). This directive is intended for web sites with large numbers of insecure legacy URLs that need to be rewritten.
CSP 和 Workers
Workers 一般来说不被创建他的文档（或者父级Worker）的CSP策略管理。如果要为Worker指定CSP策略，可以为Worker脚本的请求的响应的头部设置CSP策略。
例外的情况是，如果Worker脚本的来源是一个全局唯一ID（比如，它的URL是一个结构化的数据或者BLOB）。在这种情况下，这个Worker会继承它所属的文档或者创建它的Worker的CSP策略。
Multiple content security policies
CSP allows multiple policies being specified for a resource, including via the Content-Security-Policy header, the Content-Security-Policy-Report-Only header and a <meta> element.
You can use the Content-Security-Policy header more than once like in the example below. Pay special attention to the connect-src directive here. Even though the second policy would allow the connection, the first policy contains connect-src 'none'. Adding additional policies can only further restrict the capabilities of the protected resource, which means that there will be no connection allowed and, as the strictest policy, connect-src 'none' is enforced.
Content-Security-Policy: default-src 'self' http://example.com;
connect-src 'none';
Content-Security-Policy: connect-src http://example.com/;
script-src http://example.com/
Examples
Example: Disable unsafe inline/eval, only allow loading of resources (images, fonts, scripts, etc.) over https:
// header Content-Security-Policy: default-src https: // meta tag <meta http-equiv="Content-Security-Policy" content="default-src https:">
Example: Pre-existing site that uses too much inline code to fix but wants to ensure resources are loaded only over https and disable plugins:
Content-Security-Policy: default-src https: 'unsafe-eval' 'unsafe-inline'; object-src 'none'
Example: Don't implement the above policy yet; instead just report violations that would have occurred:
Content-Security-Policy-Report-Only: default-src https:; report-uri /csp-violation-report-endpoint/
See Mozilla Web Security Guidelines for more examples.
Specifications
| Specification | Status | Comment |
|---|---|---|
| Content Security Policy Level 3 | Editor's Draft | Adds disown-opener, manifest-src, navigation-to, report-uri, strict-dynamic, worker-src. Undeprecates frame-src. Deprecates report-uri in favor if report-to. |
| Mixed Content | Candidate Recommendation | Adds block-all-mixed-content. |
| Subresource Integrity | Recommendation | Adds require-sri-for. |
| Upgrade Insecure Requests | Candidate Recommendation | Adds upgrade-insecure-requests. |
| Content Security Policy Level 2 | Recommendation | Adds base-uri, child-src, form-action, frame-ancestors, plugin-types, referrer, reflected-xss, and report-uri. Deprecates frame-src. |
| Content Security Policy 1.0 | Candidate Recommendation | Defines connect-src, default-src, font-src, frame-src, img-src, media-src, object-src, report-uri, sandbox, script-src, and style-src. |
Browser compatibility
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