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。
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：
- 使用了非root用户运行镜像
- 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
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: 1
2022-04-14T13:38:38.579+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
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：
- 会有提示告诉你是否使用资源限制
- 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 &
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
ImagePolicyWebhook
镜像策略的工作流程
启用准入控制器插件
- 提供HTTPS证书
- 添加配置文件
- 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 508 10月 21 18:53 admission_configuration.yaml
-rwxr-xr-x 1 root root 10376657 11月 24 2019 cfssl
-rwxr-xr-x 1 root root 6595195 11月 24 2019 cfssl-certinfo
-rwxr-xr-x 1 root root 2277873 11月 24 2019 cfssljson
-rw-r--r-- 1 root root 632 10月 21 18:46 connect_webhook.yaml
-rw-r--r-- 1 root root 1367 7月 5 2021 image-policy-certs.sh
drwxr-xr-x 2 root root 39 7月 9 2021 image-policy-webhook
[root@master01:~/image-webhook]# vim image-policy-certs.sh
cat > 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 508 10月 21 18:53 admission_configuration.yaml
-rw-r--r-- 1 root root 956 4月 14 09:31 apiserver-client.csr
-rw-r--r-- 1 root root 182 4月 14 09:31 apiserver-client-csr.json
-rw------- 1 root root 1675 4月 14 09:31 apiserver-client-key.pem
-rw-r--r-- 1 root root 1306 4月 14 09:31 apiserver-client.pem
-rw-r--r-- 1 root root 294 4月 14 09:31 ca-config.json
-rw-r--r-- 1 root root 960 4月 14 09:31 ca.csr
-rw-r--r-- 1 root root 212 4月 14 09:31 ca-csr.json
-rw------- 1 root root 1675 4月 14 09:31 ca-key.pem
-rw-r--r-- 1 root root 1273 4月 14 09:31 ca.pem
-rw-r--r-- 1 root root 632 10月 21 18:46 connect_webhook.yaml
-rwxr-xr-x 1 root root 1367 7月 5 2021 image-policy-certs.sh
drwxr-xr-x 2 root root 39 7月 9 2021 image-policy-webhook
-rw-r--r-- 1 root root 1001 4月 14 09:31 webhook.csr
-rw-r--r-- 1 root root 204 4月 14 09:31 webhook-csr.json
-rw------- 1 root root 1679 4月 14 09:31 webhook-key.pem
-rw-r--r-- 1 root root 1330 4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https
name: 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 508 4月 14 09:38 admission_configuration.yaml
-rw-r--r-- 1 root root 956 4月 14 09:39 apiserver-client.csr
-rw-r--r-- 1 root root 182 4月 14 09:39 apiserver-client-csr.json
-rw------- 1 root root 1675 4月 14 09:39 apiserver-client-key.pem
-rw-r--r-- 1 root root 1306 4月 14 09:39 apiserver-client.pem
-rw-r--r-- 1 root root 1273 4月 14 09:39 ca.pem
-rw-r--r-- 1 root root 632 4月 14 09:38 connect_webhook.yaml
-rw-r--r-- 1 root root 1001 4月 14 09:39 webhook.csr
-rw-r--r-- 1 root root 204 4月 14 09:39 webhook-csr.json
-rw------- 1 root root 1679 4月 14 09:39 webhook-key.pem
-rw-r--r-- 1 root root 1330 4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：
- 使用Python编写一个连接
ImagePolicyWebhook的api接口 - 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 212 7月 9 2021 Dockerfile
-rw-r--r-- 1 root root 982 7月 9 2021 main.py
-rw-r--r-- 1 root root 1001 4月 14 09:31 webhook.csr
-rw-r--r-- 1 root root 204 4月 14 09:31 webhook-csr.json
-rw------- 1 root root 1679 4月 14 09:31 webhook-key.pem
-rw-r--r-- 1 root root 1330 4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"])
def image_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 ":" not in 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!"
break
else:
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）。
- 自签
HTTPS证书 -
Docker容器启动镜像策略服务 - 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。文章来源：https://www.toymoban.com/news/detail-452782.html
[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。文章来源地址https://www.toymoban.com/news/detail-452782.html
[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 -
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