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5.供应链安全

供应链安全

主要内容

❖ 可信任软件供应链概述

❖ 构建镜像Dockerfile文件优化

❖ 镜像漏洞扫描工具：Trivy

❖ 检查YAML文件安全配置：kubesec

❖ 准入控制器： Admission Webhook

❖ 准入控制器： ImagePolicyWebhook

可信任软件供应链概述

可信任软件供应链：指在建设基础架构过程中，涉及的软件都是可信任的。

image-20220414122733589

构建镜像Dockerfile文件优化

  • 减少镜像层：一次RUN指令形成新的一层，尽量Shell命令都写在一行，减少镜像层。
  • 清理无用文件：清理对应的残留数据，例如yum缓存。
  • 清理无用的软件包：基础镜像默认会带一些debug工具，可以删除掉，仅保留应用程序所需软件，防止黑客利用。
  • 选择最小的基础镜像：例如alpine
  • 使用非root用户运行：USER指令指定普通用户

示例：构建python web镜像

参数化构建如下：

  1. 使用了非root用户运行镜像
  2. 使用了一个镜像层，并非多层
FROM python
RUN useradd python
RUN mkdir /data/www -p
COPY . /data/www
RUN chown -R python /data
RUN pip install flask -i https://mirrors.aliyun.com/pypi/simple/ && yum makecache 
WORKDIR /data/www
USER python
CMD python main.py

镜像漏洞扫描工具：Trivy

image-20220414124314141

Trivy：是一种用于容器镜像、文件系统、Git仓库的漏洞扫描工具。发现目标软件存在的漏洞。 Trivy易于使用，只需安装二进制文件即可进行扫描，方便集成CI系统。

项目地址：https://github.com/aquasecurity/trivy

安装Trivy

在官网下载二进制的文件，移到

/usr/local/bin/

下

[root@master01:~]# mv trivy /usr/local/bin [root@master01:~]# trivy --version 
Version: 0.18.3
Vulnerability DB:
  Type: Light
  Version: 1
  UpdatedAt: 2022-04-14 00:51:13.721973471 +0000 UTC
  NextUpdate: 2022-04-14 06:51:13.721972971 +0000 UTC
  DownloadedAt: 0001-01-01 00:00:00 +0000 UTC
下载数据库超时解决

安全扫描通常都需要下载安全漏洞的下载数据库比较完整的版本。数据库速度很慢而且从github下载。所以需要离线。

GitHub项目地址： https://github.com/aquasecurity/trivy-db/releases

下载 trivy-offline.db.tgz 放在trivy cache目录。默认的cache目录的位置上

目录： 

/home/.cache/trivy/db

[root@master01:~]# cp  trivy-offline.db.tgz .cache/trivy/db/ [root@master01:~]# cd .cache/trivy/db/ [root@master01:~/.cache/trivy/db]# tar zxvf trivy-offline.db.tgz && rm -rf trivy-offline.db.tgz
Trivy使用

1.容器镜像扫描

也可以指定tar使用

trivy image -i nginx.tar

[root@master01:~]# trivy image nginx

+---------------------+------------------+----------+--------------------+-------------------------+-----------------------------------------+
| zlib1g              | CVE-2018-25032   | HIGH     |1:1.2.11.dfsg-2    |1:1.2.11.dfsg-2+deb11u1 | zlib: A flaw found in||||||| zlib v1.2.2.2 through zlib              ||||||| v1.2.11 when compressing...             ||||||| -->avd.aquasec.com/nvd/cve-2018-25032   |
+---------------------+------------------+----------+--------------------+-------------------------+-----------------------------------------+

2. 打印指定（高危、严重）漏洞信息

可以通过-s 参数指定是高危漏洞还是严重漏洞

HIGH

是高危漏洞

CRITICAL

是严重漏洞

[root@master01:~]# trivy image -s HIGH,CRITICAL nginx 2022-04-14T13:38:38.566+0800    INFO    Detected OS: debian
2022-04-14T13:38:38.567+0800    INFO    Detecting Debian vulnerabilities...
2022-04-14T13:38:38.579+0800    INFO    Number of PL dependency files: 12022-04-14T13:38:38.579+0800    INFO    Detecting jar vulnerabilities...

nginx (debian 11.2)===================
Total: 76(HIGH: 57, CRITICAL: 19)

+---------------------+------------------+----------+--------------------+-------------------------+-----------------------------------------+
|       LIBRARY       | VULNERABILITY ID | SEVERITY | INSTALLED VERSION  |      FIXED VERSION      |                  TITLE                  |
+---------------------+------------------+----------+--------------------+-------------------------+-----------------------------------------+
|curl| CVE-2021-22945   | CRITICAL |7.74.0-1.3+deb11u1 || curl: use-after-free and                ||||||| double-free in MQTT sending             ||||||| -->avd.aquasec.com/nvd/cve-2021-22945   |
+                     +------------------+----------+                    +-------------------------+-----------------------------------------+
|| CVE-2021-22946   | HIGH     ||| curl: Requirement to use                ||||||| TLS not properly enforced               |||||||for IMAP, POP3, and...                  ||||||| -->avd.aquasec.com/nvd/cve-2021-22946   |
+---------------------+------------------+          +--------------------+-------------------------+-----------------------------------------+
| e2fsprogs           | CVE-2022-1304    ||1.46.2-2           || e2fsprogs: out-of-bounds                ||||||| read/write via crafted filesystem       ||||||| -->avd.aquasec.com/nvd/cve-2022-1304    |
+---------------------+------------------+          +--------------------+-------------------------+-----------------------------------------+
|gzip| CVE-2022-1271    ||1.10-4             || gzip: arbitrary-file-write              ||||||| vulnerability                           ||||||| -->avd.aquasec.com/nvd/cve-2022-1271    |
+---------------------+------------------+----------+--------------------+-------------------------+-----------------------------------------+

检查YAML文件安全配置：kubesec

kubesec简介

image-20220414134332943

kubesec：是一个针对K8s资源清单文件进行安全配置评估的工具，根据安全配置 最佳实践来验证并给出建议。

官网：https://kubesec.io

项目地址：https://github.com/controlplaneio/kubesec

kubesec安装
[root@master01:~]# tar zxvf kubesec_linux_amd64.tar.gz 
CHANGELOG.md
LICENSE
README.md
kubesec
[root@master01:~]# mv kubesec /usr/local/bin/
kubesec使用

示例：

  1. 会有提示告诉你是否使用资源限制
  2. 可以根据建议添加要求去加固Pod的安全范围
$ kubesec scan deployment.yaml 
···
        {"id":"RequestsMemory",
          "selector":"containers[] .resources .limits .memory",
          "reason":"Enforcing memory limits prevents DOS via resource exhaustion",
          "points":1},
        {"id":"RequestsCPU",
          "selector":"containers[] .resources .requests .cpu",
          "reason":"Enforcing CPU requests aids a fair balancing of resources across the cluster",
          "points":1},

或者使用容器环境执行检查

$ docker run -i kubesec/kubesec scan /dev/stdin < deployment.yaml

kubesec内置一个HTTP服务器，可以直接启用，远程调用。

二进制

kubesec http 8080 &

image-20220414135608347

Docker容器

docker run -d -p 8080:8080 kubesec/kubesec http 8080

示例：

curl -sSX POST --data-binary @deployment.yaml http://192.168.31.71:8080/scan

Admission Webhook

Admission Webhook：准入控制器Webhook是准入控制插件的一种，用于拦截所有向APISERVER发送的 请求，并且可以修改请求或拒绝请求。

Admission webhook为开发者提供了非常灵活的插件模式，在kubernetes资源持久化之前，管理员通过程序 可以对指定资源做校验、修改等操作。例如为资源自动打标签、pod设置默认SA，自动注入sidecar容器等。

相关Webhook准入控制器：

  • MutatingAdmissionWebhook：修改资源，理论上可以监听并修改任何经过ApiServer处理的请求
  • ValidatingAdmissionWebhook：验证资源
  • ImagePolicyWebhook：镜像策略，主要验证镜像字段是否满足条件

image-20220414135937964

ImagePolicyWebhook

镜像策略的工作流程

image-20220414140015972

启用准入控制器插件
  1. 提供HTTPS证书
  2. 添加配置文件
  3. 需要启用准入控制器开启ImagePolicyWebhook插件
1.生成HTTPS证书
  • 需要使用cfssl工具、生成https证书
  • 需要admission_configuration和connect_webhook的配置文件
[root@master01:~/image-webhook]# ll
total 18820
-rw-r--r-- 1 root root      50810月 2118:53 admission_configuration.yaml
-rwxr-xr-x 1 root root 1037665711月 242019 cfssl
-rwxr-xr-x 1 root root  659519511月 242019 cfssl-certinfo
-rwxr-xr-x 1 root root  227787311月 242019 cfssljson
-rw-r--r-- 1 root root      63210月 2118:46 connect_webhook.yaml
-rw-r--r-- 1 root root     13677月   52021 image-policy-certs.sh
drwxr-xr-x 2 root root       397月   92021 image-policy-webhook

[root@master01:~/image-webhook]# vim image-policy-certs.shcat> webhook-csr.json <<EOF
{"CN":"webhook",
  "hosts":["10.11.121.111"# 修改一下IP，我这里是master],
  "key":{"algo":"rsa",
    "size":2048},
  "names":[{"C":"CN",
      "L":"BeiJing",
      "ST":"BeiJing"}]}

通过cfssl工具生成https认证

  • 生成的key和pem文件需要复制到imagepolicywebhook需要的目录
  • 还需要将两个连接webhook配置文件复制到指定目录
[root@master01:~/image-webhook]# mv cfssl* /usr/local/bin/[root@master01:~/image-webhook]# chmod +x image-policy-certs.sh [root@master01:~/image-webhook]# ./image-policy-certs.sh [root@master01:~/image-webhook]# ll
total 64
-rw-r--r-- 1 root root  50810月 2118:53 admission_configuration.yaml
-rw-r--r-- 1 root root  9564月  14 09:31 apiserver-client.csr
-rw-r--r-- 1 root root  1824月  14 09:31 apiserver-client-csr.json
-rw------- 1 root root 16754月  14 09:31 apiserver-client-key.pem
-rw-r--r-- 1 root root 13064月  14 09:31 apiserver-client.pem
-rw-r--r-- 1 root root  2944月  14 09:31 ca-config.json
-rw-r--r-- 1 root root  9604月  14 09:31 ca.csr
-rw-r--r-- 1 root root  2124月  14 09:31 ca-csr.json
-rw------- 1 root root 16754月  14 09:31 ca-key.pem
-rw-r--r-- 1 root root 12734月  14 09:31 ca.pem
-rw-r--r-- 1 root root  63210月 2118:46 connect_webhook.yaml
-rwxr-xr-x 1 root root 13677月   52021 image-policy-certs.sh
drwxr-xr-x 2 root root   397月   92021 image-policy-webhook
-rw-r--r-- 1 root root 10014月  14 09:31 webhook.csr
-rw-r--r-- 1 root root  2044月  14 09:31 webhook-csr.json
-rw------- 1 root root 16794月  14 09:31 webhook-key.pem
-rw-r--r-- 1 root root 13304月  14 09:31 webhook.pem
2.添加配置文件
  • 查看admission_configuration.yaml
  • 查看connect_webhook.yaml
  • /etc/kubernetes/image-policy/该目录是不存在的，所以需要创建，用作数据卷持久化
  • 需要修改的是connect_webhook的server地址，该地址是镜像策略服务地址，这里我使用master01
  • admission_configuration.yaml和 connect_webhook.yaml需要存放到/etc/kubernetes/image-policy/目录
[root@master01:~/image-webhook]# cat admission_configuration.yaml apiVersion: apiserver.config.k8s.io/v1
kind: AdmissionConfiguration
plugins:-name: ImagePolicyWebhook
  configuration:imagePolicy:kubeConfigFile: /etc/kubernetes/image-policy/connect_webhook.yaml  # 连接镜像策略服务器配置文件allowTTL:50# 控制批准请求的缓存时间，单位秒denyTTL:50# 控制批准请求的缓存时间，单位秒retryBackoff:500# 控制重试间隔，单位毫秒defaultAllow:true# 确定webhook后端失效的行为[root@master01:~/image-webhook]# cat connect_webhook.yaml apiVersion: v1
kind: Config
clusters:-cluster:certificate-authority: /etc/kubernetes/image-policy/webhook.pem # 数字证书，用于验证远程服务server: https://10.11.121.111:8080/image_policy # 镜像策略服务器地址，必须是httpsname: webhook
contexts:-context:cluster: webhook
    user: apiserver
  name: webhook
current-context: webhook 
preferences:{}users:-name: apiserver
  user:client-certificate: /etc/kubernetes/image-policy/apiserver-client.pem # webhook准入控制器使用的证书client-key: /etc/kubernetes/image-policy/apiserver-client-key.pem # 对应私钥证书

新建/etc/kubernetes/image-policy的目录，复制文件到该目录下

[root@master01:~/image-webhook]# mkdir /etc/kubernetes/image-policy[root@master01:~/image-webhook]# cp admission_configuration.yaml connect_webhook.yaml /etc/kubernetes/image-policy/[root@master01:~/image-webhook]# cp apiserver*  /etc/kubernetes/image-policy/[root@master01:~/image-webhook]# cp webhook* /etc/kubernetes/image-policy/[root@master01:~/image-webhook]# cp ca.pem  /etc/kubernetes/image-policy/[root@master01:~/image-webhook]# ll /etc/kubernetes/image-policy/
total 44
-rw-r--r-- 1 root root  5084月  14 09:38 admission_configuration.yaml
-rw-r--r-- 1 root root  9564月  14 09:39 apiserver-client.csr
-rw-r--r-- 1 root root  1824月  14 09:39 apiserver-client-csr.json
-rw------- 1 root root 16754月  14 09:39 apiserver-client-key.pem
-rw-r--r-- 1 root root 13064月  14 09:39 apiserver-client.pem
-rw-r--r-- 1 root root 12734月  14 09:39 ca.pem
-rw-r--r-- 1 root root  6324月  14 09:38 connect_webhook.yaml
-rw-r--r-- 1 root root 10014月  14 09:39 webhook.csr
-rw-r--r-- 1 root root  2044月  14 09:39 webhook-csr.json
-rw------- 1 root root 16794月  14 09:39 webhook-key.pem
-rw-r--r-- 1 root root 13304月  14 09:39 webhook.pem
3.开启ImagePolicyWebhook插件

使用hostpath数据卷将宿主机

/etc/kubernetes/image-policy

目录挂载到容器中。

重启kubelet，等待一分钟重建kube-apiserver的Pod。

[root@master01:~/image-webhook]# vim /etc/kubernetes/kube-apiserver.yaml ---enable-admission-plugins=NodeRestriction,ImagePolicyWebhook
    ---admission-control-config-file=/etc/kubernetes/image-policy/admission_configuration.yaml
···
    volumeMounts:-mountPath: /etc/kubernetes/image-policy
      name: image-policy
···
  volumes:-hostPath:path: /etc/kubernetes/image-policy
      type: Directory
      name: image-policy
      
[root@master01:~/image-webhook]# systemctl  restart  kubelet
4.部署镜像服务器

在本机的master节点部署镜像服务器，来当server，要求如下：

  1. 使用Python编写一个连接ImagePolicyWebhook的api接口
  2. 编写一个Dockerfile运行这个python文件
[root@master01:~/image-webhook]# mv webhook* image-policy-webhook/[root@master01:~/image-webhook/image-policy-webhook]# ll
total 24
-rw-r--r-- 1 root root  2127月   92021 Dockerfile
-rw-r--r-- 1 root root  9827月   92021 main.py
-rw-r--r-- 1 root root 10014月  14 09:31 webhook.csr
-rw-r--r-- 1 root root  2044月  14 09:31 webhook-csr.json
-rw------- 1 root root 16794月  14 09:31 webhook-key.pem
-rw-r--r-- 1 root root 13304月  14 09:31 webhook.pem

查看当前的Dockerfile文件

[root@master01:~/image-webhook/image-policy-webhook] # cat Dockerfile 
FROM python
RUN useradd python
RUN mkdir /data/www -p
COPY . /data/www
RUN chown -R python /data
RUN pip install flask -i https://mirrors.aliyun.com/pypi/simple/
WORKDIR /data/www
USER python
CMD python main.py

查看当前的Python脚本

[root@master01:~/image-webhook/image-policy-webhook]# cat main.py from flask import Flask,request
import json

app = Flask(__name__)@app.route('/image_policy',methods=["POST"])defimage_policy():
    post_data = request.get_data().decode()#print("POST数据: %s" %post_data)
    data = json.loads(post_data)for c in data['spec']['containers']:# 如果镜像里不带冒号或者带:latest说明是镜像使用latest标签if":"notin c['image']or":latest"in c['image']:  
            allowed, reason =False,"检查镜像失败！镜像标签不允许使用latest!"breakelse:
            allowed, reason =True,"检查镜像通过."print("检查结果: %s"%reason)
    result ={"apiVersion":"imagepolicy.k8s.io/v1alpha1","kind":"ImageReview","status":{"allowed": allowed,"reason": reason}}return json.dumps(result,ensure_ascii=False)if __name__ =="__main__":
    app.run(host="0.0.0.0",port=8080,ssl_context=('/data/www/webhook.pem','/data/www/webhook-key.pem'))

构建Dockerfile

[root@master01:~/image-webhook/image-policy-webhook]# docker build -t image-policy-webhook .
Digest: sha256:dbbfcbf95f6b596d2be1d8f3b368016619f78f829facf6f2e361bea1151794e5
Status: Downloaded newer image for python:latest
 ---> a5d7930b60cc
Step 2/9 : RUN useradd python
 ---> Running in fcd9fcc7e44f
Removing intermediate container fcd9fcc7e44f
 ---> 10b842f26fed
Step 3/9 : RUN mkdir /data/www -p
 ---> Running in cffd0d6f3bbd
Removing intermediate container cffd0d6f3bbd
 ---> 4db5fe4dc849
Step 4/9 : COPY . /data/www
 ---> d27fa5502133
Step 5/9 : RUN chown -R python /data
 ---> Running in 7559149b085b
Removing intermediate container 7559149b085b
 ---> a35d92963cfd
Step 6/9 : RUN pip install flask -i https://mirrors.aliyun.com/pypi/simple/
 ---> Running in 8aea1cb3d0fe
 Removing intermediate container 8aea1cb3d0fe
 ---> b81eed200f98
Step 7/9 : WORKDIR /data/www
 ---> Running in fb82b0cc633e
Removing intermediate container fb82b0cc633e
 ---> 2e43f0dff4ad
Step 8/9 :USER python
 ---> Running in 5faeb5a8566e
Removing intermediate container 5faeb5a8566e
 ---> 6797205b1622
Step 9/9 : CMD python main.py
 ---> Running in da4ae6eabc00
Removing intermediate container da4ae6eabc00
 ---> d49ca131fdb9
Successfully built d49ca131fdb9
Successfully tagged image-policy-webhook:latest
5.部署镜像服务

自己用python开发一个简单的webhook端点服务器，作用是拒绝部署的镜像乜有指定标签（即latest）。

  1. 自签HTTPS证书
  2. Docker容器启动镜像策略服务
  3. 查看当前的Docker日志
[root@master01:~/image-webhook/image-policy-webhook]# docker run -d -u root --name=image-policy-webhook \> -v $PWD/webhook.pem:/data/www/webhook.pem \> -v $PWD/webhook-key.pem:/data/www/webhook-key.pem \> -e PYTHONUNBUFFERED=1 -p 8080:8080 \> image-policy-webhook
73a9ae72a7bc8f379fe5414f575b779bf34c969089f6e544e1c7a81a60fc5b9d.

[root@master01:~/image-webhook/image-policy-webhook]# docker logs -f image-policy-webhook 
 * Serving Flask app 'main'(lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on all addresses (0.0.0.0)
   WARNING: This is a development server. Do not use it in a production deployment.
 * Running on https://127.0.0.1:8080
 * Running on https://172.17.0.2:8080 (Press CTRL+C to quit)

测试ImagePolicyWebhook

创建Deployment使用nginx镜像，使用nginx:1.16的版本，查看日志。

[root@master01 ~]# kubectl create deployment web1 --image=nginx:1.16 
deployment.apps/web1 created

[root@master01 ~]# docker logs  -f image-policy-webhook 
 * Serving Flask app 'main'(lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on all addresses (0.0.0.0)
   WARNING: This is a development server. Do not use it in a production deployment.
 * Running on https://127.0.0.1:8080
 * Running on https://172.17.0.2:8080 (Press CTRL+C to quit)
POST数据: {"kind":"ImageReview","apiVersion":"imagepolicy.k8s.io/v1alpha1","metadata":{"creationTimestamp":null},"spec":{"containers":[{"image":"nginx:1.16"}],"namespace":"default"},"status":{"allowed":false}}

检查结果: 检查镜像通过.
10.11.121.118 - - [14/Apr/2022 14:00:46]"POST /image_policy?timeout=30s HTTP/1.1"200 -
POST数据: {"kind":"ImageReview","apiVersion":"imagepolicy.k8s.io/v1alpha1","metadata":{"creationTimestamp":null},"spec":{"containers":[{"image":"nginx:latest"}],"namespace":"default"},"status":{"allowed":false}}

创建Deployment使用nginx镜像，使用nginx:latest的版本，查看日志。

[root@master01 ~]# kubectl create deployment web2 --image=nginx:latest
deployment.apps/web2 created

[root@master01 image-policy-webhook]# docker logs  -f image-policy-webhook 
 * Serving Flask app 'main'(lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
 * Running on all addresses (0.0.0.0)
   WARNING: This is a development server. Do not use it in a production deployment.
 * Running on https://127.0.0.1:8080
 * Running on https://172.17.0.2:8080 (Press CTRL+C to quit)
POST数据: {"kind":"ImageReview","apiVersion":"imagepolicy.k8s.io/v1alpha1","metadata":{"creationTimestamp":null},"spec":{"containers":[{"image":"nginx:1.16"}],"namespace":"default"},"status":{"allowed":false}}

检查结果: 检查镜像通过.
10.11.121.118 - - [14/Apr/2022 14:00:46]"POST /image_policy?timeout=30s HTTP/1.1"200 -
POST数据: {"kind":"ImageReview","apiVersion":"imagepolicy.k8s.io/v1alpha1","metadata":{"creationTimestamp":null},"spec":{"containers":[{"image":"nginx:latest"}],"namespace":"default"},"status":{"allowed":false}}

检查结果: 检查镜像失败！镜像标签不允许使用latest!10.11.121.118 - - [14/Apr/2022 14:01:04]"POST /image_policy?timeout=30s HTTP/1.1"200 -
POST数据: {"kind":"ImageReview","apiVersion":"imagepolicy.k8s.io/v1alpha1","metadata":{"creationTimestamp":null},"spec":{"containers":[{"image":"nginx:latest"}],"namespace":"default"},"status":{"allowed":false}}

检查结果: 检查镜像失败！镜像标签不允许使用latest!10.11.121.118 - - [14/Apr/2022 14:02:26]"POST /image_policy?timeout=30s HTTP/1.1"200 -
标签： 安全 python flask
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