feat: add CSRF plugin

apisix/plugins/csrf.lua

@@ -0,0 +1,161 @@
+--
+-- Licensed to the Apache Software Foundation (ASF) under one or more
+-- contributor license agreements.  See the NOTICE file distributed with
+-- this work for additional information regarding copyright ownership.
+-- The ASF licenses this file to You under the Apache License, Version 2.0
+-- (the "License"); you may not use this file except in compliance with
+-- the License.  You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+--
+local core = require("apisix.core")
+local resty_sha256 = require("resty.sha256")
+local str = require("resty.string")
+local ngx = ngx
+local ngx_encode_base64 = ngx.encode_base64
+local ngx_decode_base64 = ngx.decode_base64
+local ngx_time = ngx.time
+local cookie_time = ngx.cookie_time
+local math = math
+
+
+local schema = {
+    type = "object",
+    properties = {
+        key = {
+            description = "use to generate csrf token",
+            type = "string",
+        },
+        expires = {
+            description = "expires time(s) for csrf token",
+            type = "integer",
+            default = 7200
+        },
+        name = {
+            description = "the csrf token name",
+            type = "string",
+            default = "apisix-csrf-token"
+        }
+    },
+    required = {"key"}
+}
+
+
+local _M = {
+    version = 0.1,
+    priority = 2980,
+    name = "csrf",
+    schema = schema,
+}
+
+
+function _M.check_schema(conf)
+    return core.schema.check(schema, conf)
+end
+
+
+local function gen_sign(random, expires, key)
+    local sha256 = resty_sha256:new()
+
+    local sign = "{expires:" .. expires .. ",random:" .. random .. ",key:" .. key .. "}"
+
+    sha256:update(sign)
+    local digest = sha256:final()
+
+    return str.to_hex(digest)
+end
+
+
+local function gen_csrf_token(conf)
+    local random = math.random()
+    local sign = gen_sign(random, conf.expires, conf.key)
+
+    local token = {
+        random = random,
+        expires = conf.expires,
+        sign = sign,
+    }
+
+    local cookie = ngx_encode_base64(core.json.encode(token))
+    return cookie
+end
+
+
+local function check_csrf_token(conf, ctx, token)
+    local token_str = ngx_decode_base64(token)
+    if token_str == nil then
+        core.log.error("csrf token base64 decode error")
+        return false
+    end
+
+    local token_table, err = core.json.decode(token_str)
+    if err then
+        core.log.error("decode token error: ", err)
+        return false
+    end
+
+    local random = token_table["random"]
+    if not random then
+        core.log.error("no random in token")
+        return false
+    end
+
+    local expires = token_table["expires"]
+    if not expires then
+        core.log.error("no expires in token")
+        return false
+    end
+
+    local sign = gen_sign(random, expires, conf.key)
+    if token_table["sign"] ~= sign then
+        core.log.error("Invalid signatures")
+        return false
+    end
+
+    return true
+end
+
+
+function _M.access(conf, ctx)
+    local safe_methods = {"GET", "HEAD", "OPTIONS"}
+    local method = core.request.get_method(ctx)
+    if core.table.array_find(safe_methods, method) then
+        return
+    end
+
+    local header_token = core.request.header(ctx, conf.name)
+    if not header_token or header_token == "" then
+        return 401, {error_msg = "no csrf token in headers"}
+    end
+
+    local cookie_token = ctx.var["cookie_" .. conf.name]
+    if not cookie_token then
+        return 401, {error_msg = "no csrf cookie"}
+    end
+
+    if header_token ~= cookie_token then
+        return 401, {error_msg = "csrf token mismatch"}
+    end
+
+    local result = check_csrf_token(conf, ctx, cookie_token)
+    if not result then
+        return 401, {error_msg = "Failed to verify the csrf token signature"}
+    end
+end
+
+
+function _M.header_filter(conf, ctx)
+    local csrf_token = gen_csrf_token(conf)
+    local cookie = conf.name .. "=" .. csrf_token .. ";path=/;SameSite=Lax;Expires="
+                   .. cookie_time(ngx_time() + conf.expires)
+    core.response.add_header("Set-Cookie", cookie)
+end
+
+
+return _M

conf/config-default.yaml

@@ -333,6 +333,7 @@ plugins:                          # plugin list (sorted by priority)
   - ip-restriction                 # priority: 3000
   - ua-restriction                 # priority: 2999
   - referer-restriction            # priority: 2990
+  - csrf                           # priority: 2980
   - uri-blocker                    # priority: 2900
   - request-validation             # priority: 2800
   - openid-connect                 # priority: 2599

docs/en/latest/config.json

@@ -78,7 +78,8 @@
             "plugins/ip-restriction",
             "plugins/ua-restriction",
             "plugins/referer-restriction",
-            "plugins/consumer-restriction"
+            "plugins/consumer-restriction",
+            "plugins/csrf"
           ]
         },
         {

docs/en/latest/plugins/csrf.md

@@ -0,0 +1,136 @@
+---
+title: csrf
+---
+
+<!--
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+-->
+
+## Summary
+
+- [**Description**](#description)
+- [**Attributes**](#attributes)
+- [**How To Enable**](#how-to-enable)
+- [**Test Plugin**](#test-plugin)
+- [**Disable Plugin**](#disable-plugin)
+
+## Description
+
+The `CSRF` plugin based on the `Double Submit Cookie` way, protect your API from CSRF attacks. This plugin considers the `GET`, `HEAD` and `OPTIONS` methods to be safe operations. Therefore calls to the `GET`, `HEAD` and `OPTIONS` methods are not checked for interception.
+
+In the following we define `GET`, `HEAD` and `OPTIONS` as the `safe-methods` and those other than these as `unsafe-methods`.
+
+## Attributes
+
+| Name             | Type    | Requirement | Default | Valid | Description                                                  |
+| ---------------- | ------- | ----------- | ------- | ----- | ------------------------------------------------------------ |
+|   name   |  string |    optional    | `apisix-csrf-token`  |    | The name of the token in the generated cookie. |
+| expires |  number | optional | `7200` | | Expiration time(s) of csrf cookie. |
+| key | string | required |  |  | The secret key used to encrypt the cookie. |
+
+## How To Enable
+
+1. Create the route and enable the plugin.
+
+```shell
+curl -i http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT-d '
+{
+  "uri": "/hello",
+  "plugins": {
+    "csrf": {
+      "key": "edd1c9f034335f136f87ad84b625c8f1"
+    }
+  },
+  "upstream": {
+    "type": "roundrobin",
+    "nodes": {
+      "127.0.0.1:9001": 1
+    }
+  }
+}'
+```
+
+The route is then protected, and if you access it using methods other than `GET`, you will see that the request was blocked and receive a 401 status code back.
+
+2. Using `GET` requests `/hello`, a cookie with an encrypted token is received in the response. Token name is the `name` field set in the plugin configuration, if not set, the default value is `apisix-csrf-token`.
+
+Please note: We return a new cookie for each request.
+
+3. In subsequent unsafe-methods requests to this route, you need to read the encrypted token from the cookie and append the token to the `request header`, setting the field name to the `name` in the plugin configuration.
+
+## Test Plugin
+
+Direct access to the '/hello' route using a `POST` method will return an error:
+
+```shell
+curl -i http://127.0.0.1:9080/hello -X POST
+
+HTTP/1.1 401 Unauthorized
+...
+{"error_msg":"no csrf token in headers"}
+```
+
+When accessed with a GET request, the correct return and a cookie with an encrypted token are obtained:
+
+```shell
+curl -i http://127.0.0.1:9080/hello
+
+HTTP/1.1 200 OK
+Set-Cookie: apisix-csrf-token=eyJyYW5kb20iOjAuNjg4OTcyMzA4ODM1NDMsImV4cGlyZXMiOjcyMDAsInNpZ24iOiJcL09uZEF4WUZDZGYwSnBiNDlKREtnbzVoYkJjbzhkS0JRZXVDQm44MG9ldz0ifQ==;path=/;Expires=Mon, 13-Dec-21 09:33:55 GMT
+```
+
+The token needs to be read from the cookie and carried in the request header in subsequent unsafe-methods requests.
+
+For example, use [js-cookie](https://github.com/js-cookie/js-cookie) read cookie and [axios](https://github.com/axios/axios) send request in client:
+
+```js
+const token = Cookie.get('apisix-csrf-token');
+
+const instance = axios.create({
+  headers: {'apisix-csrf-token': token}
+});
+```
+
+You also need to make sure that you carry the cookie.
+
+Use curl send request:
+
+```shell
+curl -i http://127.0.0.1:9080/hello -X POST -H 'apisix-csrf-token: eyJyYW5kb20iOjAuNjg4OTcyMzA4ODM1NDMsImV4cGlyZXMiOjcyMDAsInNpZ24iOiJcL09uZEF4WUZDZGYwSnBiNDlKREtnbzVoYkJjbzhkS0JRZXVDQm44MG9ldz0ifQ==' -b 'apisix-csrf-token=eyJyYW5kb20iOjAuNjg4OTcyMzA4ODM1NDMsImV4cGlyZXMiOjcyMDAsInNpZ24iOiJcL09uZEF4WUZDZGYwSnBiNDlKREtnbzVoYkJjbzhkS0JRZXVDQm44MG9ldz0ifQ=='
+
+HTTP/1.1 200 OK
+```
+
+## Disable Plugin
+
+Send a request to update the route to disable the plugin:
+
+```shell
+curl http://127.0.0.1:9080/apisix/admin/routes/1 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
+{
+  "uri": "/hello",
+  "upstream": {
+    "type": "roundrobin",
+    "nodes": {
+      "127.0.0.1:1980": 1
+    }
+  }
+}'
+```
+
+CSRF plugin have been disabled.

docs/zh/latest/config.json

@@ -77,7 +77,8 @@
             "plugins/ip-restriction",
             "plugins/ua-restriction",
             "plugins/referer-restriction",
-            "plugins/consumer-restriction"
+            "plugins/consumer-restriction",
+            "plugins/csrf"
           ]
         },
         {