kubernetes API服务器的安全防护

12.1.了解认证机制

  启动API服务器时,通过命令行选项可以开启认证插件。

12.1.1.用户和组

了解用户:

  分为两种连接到api服务器的客户端:

  1.真实的人

  2.pod,使用一种称为ServiceAccount的机制

了解组:

  认证插件会连同用户名,和用户id返回组,组可以一次性给用户服务多个权限,不用单次赋予,

  system:unauthenticated组:用于所有认证插件都不会认证客户端身份的请求。

  system:authenticated组:会自动分配给一个成功通过认证的用户。

  system:serviceaccount组:包含 所有在系统中的serviceaccount。

  system:serviceaccount:<namespace>组:包含了所有在特定命名空间中的serviceAccount。

 

12.1.2 ServiceAccount介绍

  每个pod中都包含/var/run/secrets/kubernetes.io/serviceaccount/token文件,如下图所示,文件内容用于对身份进行验证,token文件持有serviceaccount的认证token。

  

  应用程序使用token去连接api服务器时,认证插件会对serviceaccount进行身份认证,并将serviceaccount的用户名传回到api服务器内部。

       serviceaccount的用户名格式如下:

  system:serviceaccount:<namespace>:<service account name>

  ServiceAccount是运行在pod中的应用程序,和api服务器身份认证的一中方式

了解ServiceAccount资源

  ServiceAcount作用在单一命名空间,为每个命名空间创建默认的ServiceAccount。

       

  多个pod可以使用相同命名空间下的同一的ServiceAccount

 ServiceAccount如何与授权文件绑定

   在pod的manifest文件中,可以指定账户名称的方式,将一个serviceAccount赋值给一个pod,如果不指定,将使用该命名空间下默认的ServiceAccount.

   可以 将不同的ServiceAccount赋值给pod,让pod访问不同的资源。

 

12.1.3创建ServiceAccount

  为了集群的安全性,可以手动创建ServiceAccount,可以限制只有允许的pod访问对应的资源。

        创建方法如下:

$ kubectl get sa
NAME      SECRETS   AGE
default   1         21h


$ kubectl create serviceaccount yaohong
serviceaccount/yaohong created


$ kubectl get sa
NAME      SECRETS   AGE
default   1         21h
yaohong   1         3s

  使用describe来查看ServiceAccount。

$ kubectl describe sa yaohong
Name:                yaohong
Namespace:           default
Labels:              <none>
Annotations:         <none>
Image pull secrets:  <none>
Mountable secrets:   yaohong-token-qhbxn   //如果强制使用可挂载秘钥。那么使用这个serviceaccount的pod只能挂载这个秘钥
Tokens:              yaohong-token-qhbxn
Events:              <none>

  查看该token,

$ kubectl describe secret yaohong-token-qhbxn
Name:         yaohong-token-qhbxn
Namespace:    default
Labels:       <none>
Annotations:  kubernetes.io/service-account.name: yaohong
              kubernetes.io/service-account.uid: a3d0d2fe-bb43-11e9-ac1e-005056870b4d

Type:  kubernetes.io/service-account-token

Data
====
ca.crt:     1342 bytes
namespace:  7 bytes
token:      eyJhbGciOiJSUzI1NiIsImtpZCI6IiJ9.eyJpc3MiOiJrdWJlcm5ldGVzL3NlcnZpY2VhY2NvdW50Iiwia3ViZXJuZXRlcy5pby9zZXJ2aWNlYWNjb3VudC9uYW1lc3BhY2UiOiJkZWZhdWx0Iiwia3ViZXJuZXRlcy5pby9zZXJ2aWNlYWNjb3VudC9zZWNyZXQubmFtZSI6Inlhb2hvbmctdG9rZW4tcWhieG4iLCJrdWJlcm5ldGVzLmlvL3NlcnZpY2VhY2NvdW50L3NlcnZpY2UtYWNjb3VudC5uYW1lIjoieWFvaG9uZyIsImt1YmVybmV0ZXMuaW8vc2VydmljZWFjY291bnQvc2VydmljZS1hY2NvdW50LnVpZCI6ImEzZDBkMmZlLWJiNDMtMTFlOS1hYzFlLTAwNTA1Njg3MGI0ZCIsInN1YiI6InN5c3RlbTpzZXJ2aWNlYWNjb3VudDpkZWZhdWx0Onlhb2hvbmcifQ.BwmbZKoM95hTr39BuZhinRT_vHF-typH4anjkL0HQxdVZEt_eie5TjUECV9UbLRRYIqYamkSxmyYapV150AQh-PvdcLYPmwKQLJDe1-7VC4mO2IuVdMCI_BnZFQBJobRK9EdPdbZ9uxc9l0RL5I5WyWoIjiwbrQvtCUEIkjT_99_NngdrIr7QD9S5SxHurgE3HQbmzC6ItU911LjmxtSvBqS5NApJoJaztDv0cHKvlT67ZZbverJaStQdxr4yiRbpSycRNArHy-UZKbNQXuzaZczSjVouo5A5hzgSHEBBJkQpQ6Tb-Ko5XGjjCgV_b9uQvhmgdPAus8GdFTTFAbCBw

  

12.1.4将ServiceAccount分配给pod

  在pod中定义的spec.serviceAccountName字段上设置,此字段必须在pod创建时设置后续不能被修改。

  自定义pod的ServiceAccount的方法如下图

      

 

12.2通过基于角色的权限控制加强集群安全

12.2.1.介绍RBAC授权插件

  RBAC授权插件将用户角色作为决定用户能否执行操作的关机因素

12.2.2介绍RBAC授权资源

  RBAC授权规则通过四种资源来进行配置的,他们可以分为两组:

    Role和ClusterRole,他们决定资源上可执行哪些动词。

         RoleBinding和ClusterRoleBinding,他们将上述角色绑定到特定的用户,组或者ServiceAccounts上。

  Role和RoleBinding是namespace级别资源

  ClusterRole和ClusterRoleBinding是集群级别资源

 

12.2.3使用Role和RoleBinding

   Role资源定义了哪些操作可以在哪些资源上执行,

创建Role

  service-reader.yml

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  namespace: kube-system
  name: service-reader
rules:
- apiGroups: [""]
  verbs: ["get", "list"]
  resources: ["services"]

  在kube-system中创建Role

#kubectl -n kube-system create -f service-reader.yml

  查看该namespace下的role

$ kubectl -n kube-system get role
NAME                                             AGE
extension-apiserver-authentication-reader        41h
kube-state-metrics-resizer                       41h
service-reader                                   2m17s
system::leader-locking-kube-controller-manager   41h
system::leader-locking-kube-scheduler            41h
system:controller:bootstrap-signer               41h
system:controller:cloud-provider                 41h
system:controller:token-cleaner                  41h

绑定角色到ServiceAccount

   将service-reader角色绑定到default ServiceAccount

$ kubectl  create rolebinding test --role=service-reader
rolebinding.rbac.authorization.k8s.io/test created

  

$ kubectl  get rolebinding test -o yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  creationTimestamp: 2019-08-11T03:40:51Z
  name: test
  namespace: default
  resourceVersion: "239323"
  selfLink: /apis/rbac.authorization.k8s.io/v1/namespaces/default/rolebindings/test
  uid: d0aff243-bbe9-11e9-ac1e-005056870b4d
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: service-reader

  

12.2.4使用ClusterRole和ClusterRoleBinding

 查看集群ClusterRole

# kubectl get clusterrole 
NAME                                                                   AGE
admin                                                                  42h
cluster-admin                                                          42h
edit                                                                   42h
flannel                                                                42h
kube-state-metrics                                                     42h
system:aggregate-to-admin                                              42h
...

创建ClusterRole

kubectl create clusterrole flannel --verb=get,list -n kube-system 

查看yaml文件

# kubectl get  clusterrole flannel -o yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"rbac.authorization.k8s.io/v1","kind":"ClusterRole","metadata":{"annotations":{},"name":"flannel"},"rules":[{"apiGroups":[""],"resources":["pods"],"verbs":["get"]},{"apiGroups":[""],"resources":["nodes"],"verbs":["list","watch"]},{"apiGroups":[""],"resources":["nodes/status"],"verbs":["patch"]}]}
  creationTimestamp: 2019-08-09T09:58:42Z
  name: flannel
  resourceVersion: "360"
  selfLink: /apis/rbac.authorization.k8s.io/v1/clusterroles/flannel
  uid: 45100f6f-ba8c-11e9-8f57-005056870608
rules:
- apiGroups:
  - ""
  resources:
  - pods
  verbs:
  - get
- apiGroups:
  - ""
  resources:
  - nodes
  verbs:
  - list
  - watch
- apiGroups:
  - ""
  resources:
  - nodes/status
  verbs:
  - patch

 

创建clusterRoleBinding

$ kubectl  create clusterrolebinding  cluster-tetst  --clusterrole=pv-reader  --serviceaccount=kuebsystem:yaohong 
clusterrolebinding.rbac.authorization.k8s.io/cluster-tetst created

  

 

12.2.5了解默认的ClusterRole和ClusterRoleBinding

如下所示使用kubectl get clusterroles和kubectl get clusterrolesbinding可以获取k8s默认资源。

用edit ClusterRole允许对资源进行修改

用admin ClusterRole赋予一个命名空间全部的权限

$ kubectl get clusterroles
NAME                                                                   AGE
admin                                                                  44h
cluster-admin                                                          44h
edit                                                                   44h
flannel                                                                44h
kube-state-metrics                                                     44h
system:aggregate-to-admin                                              44h
system:aggregate-to-edit                                               44h
system:aggregate-to-view                                               44h
system:auth-delegator                                                  44h
system:aws-cloud-provider                                              44h
system:basic-user                                                      44h
system:certificates.k8s.io:certificatesigningrequests:nodeclient       44h
system:certificates.k8s.io:certificatesigningrequests:selfnodeclient   44h
system:controller:attachdetach-controller                              44h
system:controller:certificate-controller                               44h
system:controller:clusterrole-aggregation-controller                   44h
。。。

  

wps@wps:~$ kubectl get clusterrolebindings
NAME                                                   AGE
clust-tetst                                            17m
cluster-admin                                          44h
cluster-tetst                                          13m
flannel                                                44h
kube-state-metrics                                     44h
kubelet-bootstrap                                      44h
system:aws-cloud-provider                              44h
system:basic-user                                      44h
system:controller:attachdetach-controller              44h
system:controller:certificate-controller               44h
。。。

 

posted @ 2019-08-11 14:54 姚红 阅读(...) 评论(...) 编辑 收藏