关于kubernetes:23kubernetesk8s笔记-认证授权与准入控制三-RBAC-访问控制

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RBAC 访问控制 Users Accounts

前言:

后面曾经对 ServiceAccount、Users Account 认证进行了介绍与创立, 但最初的测试发现是 Users Account 并没有拜访权限, 本节介绍 RBAC 受权 对 ServiceAccount、Users Account 认证进行受权

  • RBAC 是什么？
    RBAC 是基于角色的访问控制（Role-Based Access Control）在 RBAC 中，权限与角色相关联，用户通过成为适当角色的成员而失去这些角色的权限。这就极大地简化了权限的治理。这样治理都是层级相互依赖的，权限赋予给角色，而把角色又赋予用户，这样的权限设计很分明，治理起来很不便。
  • 角色
    Role：角色, 名称空间级别; 受权特定命名空间的拜访权限
    ClusterRole：集群角色, 全局级别; 受权所有命名空间的拜访权限
  • 角色绑定
    RoleBinding：将角色绑定到主体（即 subject）, 意味着，用户仅失去了特定名称空间下的 Role 的权限，作用范畴也限于该名称空间;
    ClusterRoleBinding：将集群角色绑定到主体, 让用户表演指定的集群角色; 意味着，用户失去了是集群级别的权限，作用范畴也是集群级别;
  • 主体（subject）
    User：用户
    Group：用户组
    ServiceAccount：服务账号
  • 绑定对应关系
    主体 (Subject) –> RoleBinding –> Role #主体取得名称空间下的 Role 的权限
    主体 (Subject) –> ClusterRoleBinding –> clusterRoles #主体取得集群级别 clusterRoles 的权限
    主体(Subject) –> Rolebindig –>ClusterRole #权限降级 主体取得名称空间下的 clusterRoles 的权限
  • rules 中的参数阐明：
    1、apiGroups：反对的 API 组列表，例如：”apiVersion: batch/v1″ 等
    2、resources：反对的资源对象列表，例如 pods、deplayments、jobs 等
    3、resourceNames: 指定 resource 的名称
    3、verbs：对资源对象的操作方法列表。

  • RBAC 应用 rbac.authorization.k8s.io API Group 来实现受权决策，容许管理员通过 Kubernetes API 动静配置策略，要启用 RBAC，须要在 apiserver 中增加参数 –authorization-mode=RBAC，如果应用的 kubeadm 装置的集群，都默认开启了 RBAC，能够通过查看 Master 节点上 apiserver 的动态 Pod 定义文件：
[root@k8s-master usercerts]# cat /etc/kubernetes/manifests/kube-apiserver.yaml 
apiVersion: v1
kind: Pod
metadata:
 ...
spec:
  containers:
  - command:
    - kube-apiserver
    - --advertise-address=192.168.4.170
    - --allow-privileged=true
    - --authorization-mode=Node,RBAC   #默认反对 BRAC 基于角色的访问控制
    - --client-ca-file=/etc/kubernetes/pki/ca.crt
    - --enable-admission-plugins=NodeRestriction
    - --enable-bootstrap-token-auth=true
    - --etcd-cafile=/etc/kubernetes/pki/etcd/ca.crt
    - --etcd-certfile=/etc/kubernetes/pki/apiserver-etcd-client.crt
...
  • 查看 kube-system 名称空间下的 role 角色详情
[root@k8s-master ~]# kubectl get role -n kube-system
NAME                                             CREATED AT
extension-apiserver-authentication-reader        2021-06-28T17:43:31Z
kube-proxy                                       2021-06-28T17:43:33Z
kubeadm:kubelet-config-1.19                      2021-06-28T17:43:31Z
kubeadm:nodes-kubeadm-config                     2021-06-28T17:43:31Z
system::leader-locking-kube-controller-manager   2021-06-28T17:43:31Z
system::leader-locking-kube-scheduler            2021-06-28T17:43:31Z
system:controller:bootstrap-signer               2021-06-28T17:43:31Z
system:controller:cloud-provider                 2021-06-28T17:43:31Z
system:controller:token-cleaner                  2021-06-28T17:43:31Z

[root@k8s-master ~]# kubectl get role kube-proxy -n kube-system -o yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  creationTimestamp: "2021-06-28T17:43:33Z"
  managedFields:
  - apiVersion: rbac.authorization.k8s.io/v1
    fieldsType: FieldsV1
    fieldsV1:
      f:rules: {}
    manager: kubeadm
    operation: Update
    time: "2021-06-28T17:43:33Z"
  name: kube-proxy
  namespace: kube-system
  resourceVersion: "195"
  selfLink: /apis/rbac.authorization.k8s.io/v1/namespaces/kube-system/roles/kube-proxy
  uid: a5404b1f-90f0-447f-b104-86fcbdd388e0
rules:   #角色规定详细信息
- apiGroups:
  - ""
  resourceNames:
  - kube-proxy
  resources:
  - configmaps
  verbs:   #能执行的操作
  - get
  • role 角色绑定
  • RoleBinding 角色绑定
[root@k8s-master ~]# kubectl explain rolebinding
KIND:     RoleBinding
VERSION:  rbac.authorization.k8s.io/v1
...
   roleRef    <Object> -required-
     RoleRef can reference a Role in the current namespace or a ClusterRole in
     the global namespace. If the RoleRef cannot be resolved, the Authorizer
     must return an error.

   subjects    <[]Object>
     Subjects holds references to the objects the role applies to.

示例 1: 创立 role 角色绑定 作用域为名称空间

[root@k8s-master authfiles]# cat pods-reader-rbac.yaml 
kind : Role
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  namespace: default
  name: pods-reader
rules:
- apiGroups: [""]  #空示意默认群组
  resources: ["pods","services","pods/log"]  #对象资源
  verbs: ["get","list","watch"]  #权限

[root@k8s-master authfiles]# cat tom-pods-reader.yaml 
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1
metadata:
  name: tom-pods-reader
  namespace: default
subjects:
- kind: User
  name: tom   #绑定的用户名
  apiGroup: rbac.authorization.k8s.io
roleRef:
  kind: Role
  name: pods-reader  #绑定之前的角色
  apiGroup: rbac.authorization.k8s.io
  
[root@k8s-master authfiles]# kubectl apply -f pods-reader-rbac.yaml 
[root@k8s-master authfiles]# kubectl apply -f tom-pods-reader.yaml 

[root@k8s-master authfiles]# kubectl get role
NAME          CREATED AT
pods-reader   2021-08-24T07:33:54Z
[root@k8s-master authfiles]# kubectl get rolebinding
NAME              ROLE               AGE
tom-pods-reader   Role/pods-reader   15m
  • 应用 tom 用户验证权限 pod、svc
[root@k8s-master authfiles]# kubectl config get-contexts   --kubeconfig=/tmp/mykubeconfig  #查看以后用户
CURRENT   NAME             CLUSTER      AUTHINFO   NAMESPACE
*         tom@kubernetes   kubernetes   tom 

[root@k8s-master authfiles]# kubectl get pod --kubeconfig=/tmp/mykubeconfig
NAME                                 READY   STATUS    RESTARTS   AGE
centos-deployment-66d8cd5f8b-bnnw6   1/1     Running   0          7m8s
[root@k8s-master authfiles]# kubectl get svc --kubeconfig=/tmp/mykubeconfig
NAME          TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
demoapp       ClusterIP   10.97.26.1     <none>        80/TCP     10d
demoapp-svc   ClusterIP   10.99.170.77   <none>        80/TCP     10d
demodb        ClusterIP   None           <none>        9907/TCP   5d22h
kubernetes    ClusterIP   10.96.0.1      <none>        443/TCP    10d
  • 验证 deployment、nodes 权限 没有受权拜访失败
[root@k8s-master authfiles]# kubectl get deployment  --kubeconfig=/tmp/mykubeconfig
Error from server (Forbidden): deployments.apps is forbidden: User "tom" cannot list resource "deployments" in API group "apps" in the namespace "default"

[root@k8s-master authfiles]# kubectl get nodes  --kubeconfig=/tmp/mykubeconfig
Error from server (Forbidden): nodes is forbidden: User "tom" cannot list resource "nodes" in API group "" at the cluster scope

内建管理员 admin

  • 名称空间管理员 admin
  • clusterrole admin 名称空间级别资源 领有所有名称空间下的资源 所有操作权限
  • 集群管理员 cluster-admin
  • clusterrole cluster-admin 集群级别资源 领有集群所有空的资源 所有操作权限
  • 之前绑定的 rolebinding 只对默认名称空间有肯定的权限
[root@k8s-master authfiles]# kubectl get pod -n longhorn-system  --kubeconfig=/tmp/mykubeconfig
Error from server (Forbidden): pods is forbidden: User "tom" cannot list resource "pods" in API group ""in the namespace"longhorn-system"
  • clusterrole admin 对所有名称空间下的资源权限
[root@k8s-master authfiles]# kubectl get clusterrole admin
NAME    CREATED AT
admin   2021-06-28T17:43:30Z
[root@k8s-master authfiles]# kubectl get clusterrole admin -o yaml
  • 删除绑定, 从新绑定到 clusterrole admin
[root@k8s-master authfiles]# kubectl get rolebinding
NAME              ROLE               AGE
tom-pods-reader   Role/pods-reader   35m

[root@k8s-master authfiles]# kubectl delete Role/pods-reader
role.rbac.authorization.k8s.io "pods-reader" deleted

[root@k8s-master authfiles]# kubectl delete rolebinding/tom-pods-reader
rolebinding.rbac.authorization.k8s.io "tom-pods-reader" deleted

[root@k8s-master authfiles]# kubectl get pod  --kubeconfig=/tmp/mykubeconfig
Error from server (Forbidden): pods is forbidden: User "tom" cannot list resource "pods" in API group ""in the namespace"default"

示例 2: 绑定 admin 并验证权限, 作用域为名称空间

[root@k8s-master authfiles]# kubectl create --help  
...
Available Commands:
  clusterrole         Create a ClusterRole.
  clusterrolebinding  Create a ClusterRoleBinding for a particular ClusterRole
  configmap           Create a configmap from a local file, directory or literal value
  cronjob             Create a cronjob with the specified name.
  deployment          Create a deployment with the specified name.
  job                 Create a job with the specified name.
  namespace           Create a namespace with the specified name
  poddisruptionbudget Create a pod disruption budget with the specified name.
  priorityclass       Create a priorityclass with the specified name.
  quota               Create a quota with the specified name.
  role                Create a role with single rule.
  rolebinding         Create a RoleBinding for a particular Role or ClusterRole
  secret              Create a secret using specified subcommand
  service             Create a service using specified subcommand.
  serviceaccount      Create a service account with the specified name
  • 能够别离对 –user、–group、–serviceaccount 进行受权
[root@k8s-master authfiles]# kubectl create clusterrolebinding  --help
Create a ClusterRoleBinding for a particular ClusterRole.
....
Usage:  
  kubectl create clusterrolebinding NAME --clusterrole=NAME [--user=username] [--group=groupname]
[--serviceaccount=namespace:serviceaccountname] [--dry-run=server|client|none] [options]
  • 绑定并进行权限验证
[root@k8s-master authfiles]# kubectl create clusterrolebinding tom-admin --user=tom  --clusterrole=admin
clusterrolebinding.rbac.authorization.k8s.io/tom-admin created

[root@k8s-master authfiles]# kubectl get pod -n longhorn-system  --kubeconfig=/tmp/mykubeconfig
NAME                                        READY   STATUS    RESTARTS   AGE
csi-attacher-54c7586574-bh88g               1/1     Running   5          7d
csi-attacher-54c7586574-fvv4p               1/1     Running   7          19d
csi-attacher-54c7586574-zkzrg               1/1     Running   10         19d
csi-provisioner-5ff5bd6b88-9tqnh            1/1     Running   5          7d
csi-provisioner-5ff5bd6b88-bs687            1/1     Running   8          19d
csi-provisioner-5ff5bd6b88-qkzt4            1/1     Running   12         19d
csi-resizer-7699cdfc4-4w49w                 1/1     Running   8          19d
......

[root@k8s-master authfiles]# kubectl get pod -n kube-system  --kubeconfig=/tmp/mykubeconfig
NAME                                 READY   STATUS    RESTARTS   AGE
coredns-f9fd979d6-l9zck              1/1     Running   16         56d
coredns-f9fd979d6-s8fp5              1/1     Running   15         56d
etcd-k8s-master                      1/1     Running   12         56d
kube-apiserver-k8s-master            1/1     Running   16         56d
kube-controller-manager-k8s-master   1/1     Running   39         56d
kube-flannel-ds-6sppx                1/1     Running   1          6d22h
kube-flannel-ds-j5g9s                1/1     Running   3          6d22h
kube-flannel-ds-nfz77                1/1     Running   1          6d22h
kube-flannel-ds-sqhq2                1/1     Running   1          6d22h

[root@k8s-master authfiles]# kubectl get deployment   --kubeconfig=/tmp/mykubeconfig
NAME                READY   UP-TO-DATE   AVAILABLE   AGE
centos-deployment   1/1     1            1           6d22h
  • node 是集群级别资源 无权限
[root@k8s-master authfiles]# kubectl get node  --kubeconfig=/tmp/mykubeconfig
Error from server (Forbidden): nodes is forbidden: User "tom" cannot list resource "nodes" in API group "" at the cluster scope

[root@k8s-master authfiles]# kubectl get pv  --kubeconfig=/tmp/mykubeconfig
Error from server (Forbidden): persistentvolumes is forbidden: User "tom" cannot list resource "persistentvolumes" in API group "" at the cluster scope

示例 3: 绑定 cluster-admin 并验证权限 作用域为集群级别资源

[root@k8s-master authfiles]# kubectl delete clusterrolebinding tom-admin
clusterrolebinding.rbac.authorization.k8s.io "tom-admin" deleted

[root@k8s-master authfiles]# kubectl create clusterrolebinding tom-cluste-admin --user=tom  --clusterrole=cluster-admin
clusterrolebinding.rbac.authorization.k8s.io/tom-cluste-admin created
[root@k8s-master authfiles]# kubectl get pv  --kubeconfig=/tmp/mykubeconfig
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS      CLAIM                   STORAGECLASS   REASON   AGE
pv-nfs-demo002                             10Gi       RWX            Retain           Available                                                   21d
pv-nfs-demo003                             1Gi        RWO            Retain           Available                                                   21d
pvc-33e9acff-afd9-417e-bbfb-293cb6305fb1   1Gi        RWX            Retain           Bound       default/data-demodb-1   longhorn                5d23h
pvc-c5a0bfaa-6948-4814-886f-8bf079b00dd1   1Gi        RWX            Retain           Bound       default/data-demodb-0   longhorn                5d23h
[root@k8s-master authfiles]# kubectl get node  --kubeconfig=/tmp/mykubeconfig
NAME         STATUS   ROLES    AGE   VERSION
k8s-master   Ready    master   56d   v1.19.9
k8s-node1    Ready    <none>   56d   v1.19.9
k8s-node2    Ready    <none>   56d   v1.19.9
k8s-node3    Ready    <none>   20d   v1.19.9
  • 须要留神的是 cluster-admin 是通过 system:masters 组形式进行受权, 如果咱们在创立用户证书时,/CN=XX/O=system:masters; 那么这个用户就领有超级管理员的权限
[root@k8s-master authfiles]# kubectl describe clusterrolebinding cluster-admin
Name:         cluster-admin
Labels:       kubernetes.io/bootstrapping=rbac-defaults
Annotations:  rbac.authorization.kubernetes.io/autoupdate: true
Role:
  Kind:  ClusterRole
  Name:  cluster-admin
Subjects:
  Kind   Name            Namespace
  ----   ----            ---------
  Group  system:masters   #通过组受权所有 system:masters 都领有超级管理员权限

示例 4: rolebinding 绑定 admin 权限降级

  • 后面有提到
    User –> Rolebindig –>ClusterRole: 权限降级，
    ClusterRole，用户失去的权限仅是 ClusterRole 的权限在 Rolebinding 所属的名称空间上的一个子集;
  • 删除之前绑定
[root@k8s-master authfiles]# kubectl delete  clusterrolebinding tom-cluste-admin
clusterrolebinding.rbac.authorization.k8s.io "tom-cluste-admin" deleted
  • 创立角色绑定集群角色 权限降级 只对指定名称空间有权限
[root@k8s-master authfiles]# kubectl create  rolebinding tom-admin --user=tom  -n longhorn-system --clusterrole=admin
rolebinding.rbac.authorization.k8s.io/tom-admin created
  • 测试权限 作用域尽为 longhorn-system 名称空间
[root@k8s-master authfiles]# kubectl get pod -n kube-system  --kubeconfig=/tmp/mykubeconfig
Error from server (Forbidden): pods is forbidden: User "tom" cannot list resource "pods" in API group ""in the namespace"kube-system"

[root@k8s-master authfiles]# kubectl get pod --kubeconfig=/tmp/mykubeconfig
Error from server (Forbidden): pods is forbidden: User "tom" cannot list resource "pods" in API group ""in the namespace"default"

[root@k8s-master authfiles]# kubectl get deployment  --kubeconfig=/tmp/mykubeconfig
Error from server (Forbidden): deployments.apps is forbidden: User "tom" cannot list resource "deployments" in API group "apps" in the namespace "default"

[root@k8s-master authfiles]# kubectl get pod -n longhorn-system  --kubeconfig=/tmp/mykubeconfig
NAME                                        READY   STATUS    RESTARTS   AGE
csi-attacher-54c7586574-bh88g               1/1     Running   5          7d
csi-attacher-54c7586574-fvv4p               1/1     Running   7          19d
csi-attacher-54c7586574-zkzrg               1/1     Running   10         19d
csi-provisioner-5ff5bd6b88-9tqnh            1/1     Running   5          7d
csi-provisioner-5ff5bd6b88-bs687            1/1     Running   8          19d
csi-provisioner-5ff5bd6b88-qkzt4            1/1     Running   12         19d
csi-resizer-7699cdfc4-4w49w                 1/1     Running   8          19d
csi-resizer-7699cdfc4-f5jph                 1/1     Running   6          7d
csi-resizer-7699cdfc4-l2j49                 1/1     Running   9          19d
...

正文完
kubernetes
发表至： kubernetes
2021-12-03
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