CSRF

Cross-Site Request Forgery（CSRF，有时读作 “sea-surf”，也称 XSRF）是一类恶意利用，攻击者会从网站信任的用户那里传递未授权命令。

所有核心中间件都位于 middleware 包中：

import "github.com/labstack/echo/v5/middleware"

用法

e.Use(middleware.CSRF())

工作原理

CSRF 中间件支持 Sec-Fetch-Site header，作为现代的纵深防御方式来进行 CSRF protection，它在传统 token 机制之外实现了 OWASP 推荐的 Fetch Metadata API。

现代浏览器会自动随每个请求发送 Sec-Fetch-Site header，表明请求来源和目标之间的关系。中间件会用它做出安全决策：

same-origin 或 none：允许（完全同源或用户直接导航）
same-site：回退到 token 验证（例如子域到主域）
cross-site：对不安全方法（POST、PUT、DELETE、PATCH）默认以 403 错误阻止

对于不发送此 header 的浏览器（旧浏览器），中间件会无缝回退到传统基于 token 的 CSRF 防护。

两个选项可调整 Sec-Fetch-Site 行为：

TrustedOrigins []string：为跨站请求允许特定 origin（适用于 OAuth 回调、webhook）
AllowSecFetchSiteFunc func(c *echo.Context) (bool, error)：用于 same-site/cross-site 验证的自定义逻辑

e.Use(middleware.CSRFWithConfig(middleware.CSRFConfig{
  // Allow OAuth callbacks from a trusted provider.
  TrustedOrigins: []string{"https://oauth-provider.com"},

  // Custom validation for same-site/cross-site requests.
  AllowSecFetchSiteFunc: func(c *echo.Context) (bool, error) {
    // Your custom authorization logic here.
    return validateCustomAuth(c), nil
    // return true, err  // blocks the request with an error
    // return true, nil  // allows the request through
    // return false, nil // falls back to legacy token logic
  },
}))

基于 token 的防护

e := echo.New()
e.Use(middleware.CSRFWithConfig(middleware.CSRFConfig{
  TokenLookup: "header:X-XSRF-TOKEN",
}))

上面的示例会从 X-XSRF-TOKEN 请求 header 中提取 CSRF token。

改为从 Cookie 读取 token：

middleware.CSRFWithConfig(middleware.CSRFConfig{
  TokenLookup:    "cookie:_csrf",
  CookiePath:     "/",
  CookieDomain:   "example.com",
  CookieSecure:   true,
  CookieHTTPOnly: true,
  CookieSameSite: http.SameSiteStrictMode,
})

访问 CSRF token

服务端：token 可从上下文的 ContextKey 下取得，并可通过模板传给客户端。
客户端：token 可从 CSRF Cookie 中读取。

配置

CSRFConfig · github.com/labstack/echo/v5@5196b9b

字段说明由英文源码注释生成。

包源码中的字段
字段	类型	说明	源码
`Skipper`	`Skipper`	Skipper defines a function to skip middleware.	L29
`TrustedOrigins`	`[]string`	TrustedOrigins permits any request with `Sec-Fetch-Site` header whose `Origin` header exactly matches a configured origin. Values should be formatted as Origin header "scheme://host[:port]". See [Origin]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Origin See [Sec-Fetch-Site]: https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html#fetch-metadata-headers	L36
`AllowSecFetchSiteFunc`	`func(c *echo.Context) (bool, error)`	AllowSecFetchSiteFunc allows custom behaviour for `Sec-Fetch-Site` requests that are about to fail with CSRF error, to be allowed or replaced with custom error. This function applies to `Sec-Fetch-Site` values: - `same-site` same registrable domain (subdomain and/or different port) - `cross-site` request originates from different site See [Sec-Fetch-Site]: https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html#fetch-metadata-headers	L44
`TokenLength`	`uint8`	TokenLength is the length of the generated token.	L47
`TokenLookup`	`string`	TokenLookup is a string in the form of "<source>:<name>" or "<source>:<name>,<source>:<name>" that is used to extract token from the request. Optional. Default value "header:X-CSRF-Token". Possible values: - "header:<name>" or "header:<name>:<cut-prefix>" - "query:<name>" - "form:<name>" Multiple sources example: - "header:X-CSRF-Token,query:csrf"	L59
`Generator`	`func() string`	Generator defines a function to generate token. Optional. Defaults to randomString(TokenLength).	L63
`ContextKey`	`string`	Context key to store generated CSRF token into context. Optional. Default value "csrf".	L67
`CookieName`	`string`	Name of the CSRF cookie. This cookie will store CSRF token. Optional. Default value "csrf".	L71
`CookieDomain`	`string`	Domain of the CSRF cookie. Optional. Default value none.	L75
`CookiePath`	`string`	Path of the CSRF cookie. Optional. Default value none.	L79
`CookieMaxAge`	`int`	Max age (in seconds) of the CSRF cookie. Optional. Default value 86400 (24hr).	L83
`CookieSecure`	`bool`	Indicates if CSRF cookie is secure. Optional. Default value false.	L87
`CookieHTTPOnly`	`bool`	Indicates if CSRF cookie is HTTP only. Optional. Default value false.	L91
`CookieSameSite`	`http.SameSite`	Indicates SameSite mode of the CSRF cookie. Optional. Default value SameSiteDefaultMode.	L95
`ErrorHandler`	`func(c *echo.Context, err error) error`	ErrorHandler defines a function which is executed for returning custom errors.	L98

包源码中的函数
类型	源码
`func CSRF() echo.MiddlewareFunc`	L117
`func CSRFWithConfig(config CSRFConfig) echo.MiddlewareFunc`	L122

默认配置

var DefaultCSRFConfig = CSRFConfig{
  Skipper:        DefaultSkipper,
  TokenLength:    32,
  TokenLookup:    "header:" + echo.HeaderXCSRFToken,
  ContextKey:     "csrf",
  CookieName:     "_csrf",
  CookieMaxAge:   86400,
  CookieSameSite: http.SameSiteDefaultMode,
}

完整示例

完整、可运行的示例可在 echox cookbook 中找到。