CSP: form-action

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since August 2016.

HTTP Content-Security-Policy (CSP) 的 form-action 指令能够限定当前页面中表单的提交地址。

警告：在表单提交之后， form-action 指令是否应该阻止重定向仍有待讨论，各个浏览器对于此行为的实现也不尽相同（例如，Chrome 63 会阻止重定向，而 Firefox 57 则不会）。

CSP version 2
Directive type Navigation directive
default-src fallback No. 未设定时允许任何值。

语法

form-action 策略允许设定一个或多个源：

Content-Security-Policy: form-action <source>;
Content-Security-Policy: form-action <source> <source>;

示例

meta 标签配置

html
<meta http-equiv="Content-Security-Policy" content="form-action 'none'" />

Apache 服务器配置

bash
<IfModule mod_headers.c>
Header set Content-Security-Policy "form-action 'none';
</IfModule>

Nginx 配置

bash
add_header Content-Security-Policy "form-action 'none';"

反例

将 <form> 元素的 action 设置为内联 JavaScript 会违反 CSP 规则。

html
<meta http-equiv="Content-Security-Policy" content="form-action 'none'" />

<form action="javascript:alert('Foo')" id="form1" method="post">
  <input type="text" name="fieldName" value="fieldValue" />
  <input type="submit" id="submit" value="submit" />
</form>

<!-- Error: Refused to send form data because it violates the following Content Security Policy directive: "form-action 'none'". -->

规范

Specification
Content Security Policy Level 3
# directive-form-action

浏览器兼容性

BCD tables only load in the browser

参见