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Kubernetes RBAC-禁止授予额外权限的尝试

rbac coreos kubectl kubernetes

NarÅ«nasK · 技术社区 · 6 年前

我在用 Kubernetes v1.8.14基于定制 CoreOS 集群:

$ kubectl version --short 
Client Version: v1.10.5
Server Version: v1.8.14+coreos.0

当尝试创建以下内容时 ClusterRole :

$ cat ClusterRole.yml 
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  labels:
    kubernetes.io/bootstrapping: rbac-defaults
  name: system:coredns
rules:
- apiGroups:
  - ""
  resources:
  - endpoints
  - services
  - pods
  - namespaces
  verbs:
  - list
  - watch

我得到以下错误:

$ kubectl create -f ClusterRole.yml 
Error from server (Forbidden): error when creating "ClusterRole.yml": clusterroles.rbac.authorization.k8s.io "system:coredns" is forbidden: attempt to grant extra privileges: [PolicyRule{Resources:["endpoints"], APIGroups:[""], Verbs:["list"]} PolicyRule{Resources:["endpoints"], APIGroups:[""], Verbs:["watch"]} PolicyRule{Resources:["services"], APIGroups:[""], Verbs:["list"]} PolicyRule{Resources:["services"], APIGroups:[""], Verbs:["watch"]} PolicyRule{Resources:["pods"], APIGroups:[""], Verbs:["list"]} PolicyRule{Resources:["pods"], APIGroups:[""], Verbs:["watch"]} PolicyRule{Resources:["namespaces"], APIGroups:[""], Verbs:["list"]} PolicyRule{Resources:["namespaces"], APIGroups:[""], Verbs:["watch"]}] user=&{cluster-admin  [system:authenticated] map[]} ownerrules=[PolicyRule{Resources:["selfsubjectaccessreviews"], APIGroups:["authorization.k8s.io"], Verbs:["create"]} PolicyRule{NonResourceURLs:["/api" "/api/*" "/apis" "/apis/*" "/healthz" "/swagger-2.0.0.pb-v1" "/swagger.json" "/swaggerapi" "/swaggerapi/*" "/version"], Verbs:["get"]}] ruleResolutionErrors=[]

据我所知我正在连接 cluster-admin ,因此应该有足够的权限来实现我要实现的目标。以下是相关的 群集管理 配置:

$ cat ~/.kube/config
apiVersion: v1
kind: Config
current-context: dev
preferences:
  colors: true

clusters:
- cluster:
    certificate-authority: cluster-ca.pem
    server: https://k8s.loc:4430
  name: dev

contexts:
- context:
    cluster: dev
    namespace: kube-system
    user: cluster-admin
  name: dev

users:
- name: cluster-admin
  user:
    client-certificate: cluster.pem
    client-key: cluster-key.pem


$ kubectl get clusterrole cluster-admin -o yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  annotations:
    rbac.authorization.kubernetes.io/autoupdate: "true"
  creationTimestamp: 2018-07-30T14:44:44Z
  labels:
    kubernetes.io/bootstrapping: rbac-defaults
  name: cluster-admin
  resourceVersion: "1164791"
  selfLink: /apis/rbac.authorization.k8s.io/v1/clusterroles/cluster-admin
  uid: 196ffecc-9407-11e8-bd67-525400ac0b7d
rules:
- apiGroups:
  - '*'
  resources:
  - '*'
  verbs:
  - '*'
- nonResourceURLs:
  - '*'
  verbs:
  - '*'


$ kubectl get clusterrolebinding cluster-admin -o yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  annotations:
    rbac.authorization.kubernetes.io/autoupdate: "true"
  creationTimestamp: 2018-07-30T14:44:45Z
  labels:
    kubernetes.io/bootstrapping: rbac-defaults
  name: cluster-admin
  resourceVersion: "1164832"
  selfLink: /apis/rbac.authorization.k8s.io/v1/clusterrolebindings/cluster-admin
  uid: 19e516a6-9407-11e8-bd67-525400ac0b7d
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- apiGroup: rbac.authorization.k8s.io
  kind: Group
  name: system:masters


$ kubectl get serviceaccount cluster-admin -o yaml
apiVersion: v1
kind: ServiceAccount
metadata:
  creationTimestamp: 2018-07-30T13:32:13Z
  name: cluster-admin
  namespace: kube-system
  resourceVersion: "1158783"
  selfLink: /api/v1/namespaces/kube-system/serviceaccounts/cluster-admin
  uid: f809e079-93fc-11e8-8b85-525400546bcd
secrets:
- name: cluster-admin-token-t7s4c

我知道这是RBAC问题,但不知道如何进一步调试。

编辑-1。

我试过建议,不幸的是没有快乐。。。

$ kubectl get clusterrolebinding cluster-admin-binding -o yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  creationTimestamp: 2018-07-31T09:21:34Z
  name: cluster-admin-binding
  resourceVersion: "1252260"
  selfLink: /apis/rbac.authorization.k8s.io/v1/clusterrolebindings/cluster-admin-binding
  uid: 1e1c0647-94a3-11e8-9f9b-525400ac0b7d
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: cluster-admin
  namespace: default


$ kubectl describe secret $(kubectl get secret | awk '/cluster-admin/{print $1}')
Name:         cluster-admin-token-t7s4c
Namespace:    kube-system
Labels:       <none>
Annotations:  kubernetes.io/service-account.name=cluster-admin
              kubernetes.io/service-account.uid=f809e079-93fc-11e8-8b85-525400546bcd

Type:  kubernetes.io/service-account-token

Data
====
ca.crt:     1785 bytes
namespace:  11 bytes
token:      eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.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.rC1x9Or8GArkhC3P0s-l_Pc0e6TEUwfbJtXAN2w-cOaRUCNCo6r4WxXKu32ngOg86TXqCho2wBopXtbJ2CparIb7FWDXzri6O6LPFzHWNzZo3b-TON2yxHMWECGjpbbqjDgkPKDEldkdxJehDBJM_GFAaUdNyYpFFsP1_t3vVIsf2DpCjeMlOBSprYRcEKmDiE6ehF4RSn1JqB7TVpvTZ_WAL4CRZoTJtZDVoF75AtKIADtVXTxVv_ewznDCKUWDupg5Jk44QSMJ0YiG30QYYM699L5iFLirzD5pj0EEPAoMeOqSjdp7KvDzIM2tBiu8YYl6Fj7pG_53WjZrvlSk5pgPLS-jPKOkixFM9FfB2eeuP0eWwLO5wvU5s--a2ekkEhaqHTXgigeedudDA_5JVIJTS0m6V9gcbE4_kYRpU7_QD_0TR68C5yxUL83KfOzj6A_S6idOZ-p7Ni6ffE_KlGqqcgUUR2MTakJgimjn0gYHNaIqmHIu4YhrT-jffP0-5ZClbI5srj-aB4YqGtCH9w5_KBYD4S2y6Rjv4kO00nZyvi0jAHlZ6el63TQPWYkjyPL2moF_P8xcPeoDrF6o8bXDzFqlXLqda2Nqyo8LMhLxjpe_wFeGuwzIUxwwtH1RUR6BISRUf86041aa2PeJMqjTfaU0u_SvO-yHMGxZt3o

然后修改 ~/.kube/config :

$ cat ~/.kube/config
apiVersion: v1
kind: Config
current-context: dev
preferences:
  colors: true

clusters:
- cluster:
    certificate-authority: cluster-ca.pem
    server: https://k8s.loc:4430
  name: dev

contexts:
- context:
    cluster: dev
    namespace: kube-system
    user: cluster-admin-2
  name: dev

users:
- name: cluster-admin
  user:
    client-certificate: cluster.pem
    client-key: cluster-key.pem
- name: cluster-admin-2
  user:
    token: eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.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.rC1x9Or8GArkhC3P0s-l_Pc0e6TEUwfbJtXAN2w-cOaRUCNCo6r4WxXKu32ngOg86TXqCho2wBopXtbJ2CparIb7FWDXzri6O6LPFzHWNzZo3b-TON2yxHMWECGjpbbqjDgkPKDEldkdxJehDBJM_GFAaUdNyYpFFsP1_t3vVIsf2DpCjeMlOBSprYRcEKmDiE6ehF4RSn1JqB7TVpvTZ_WAL4CRZoTJtZDVoF75AtKIADtVXTxVv_ewznDCKUWDupg5Jk44QSMJ0YiG30QYYM699L5iFLirzD5pj0EEPAoMeOqSjdp7KvDzIM2tBiu8YYl6Fj7pG_53WjZrvlSk5pgPLS-jPKOkixFM9FfB2eeuP0eWwLO5wvU5s--a2ekkEhaqHTXgigeedudDA_5JVIJTS0m6V9gcbE4_kYRpU7_QD_0TR68C5yxUL83KfOzj6A_S6idOZ-p7Ni6ffE_KlGqqcgUUR2MTakJgimjn0gYHNaIqmHIu4YhrT-jffP0-5ZClbI5srj-aB4YqGtCH9w5_KBYD4S2y6Rjv4kO00nZyvi0jAHlZ6el63TQPWYkjyPL2moF_P8xcPeoDrF6o8bXDzFqlXLqda2Nqyo8LMhLxjpe_wFeGuwzIUxwwtH1RUR6BISRUf86041aa2PeJMqjTfaU0u_SvO-yHMGxZt3o

然后试着用同样的方法 群集角色 ,导致了相同的错误:

$ kubectl apply -f ClusterRole.yml 
Error from server (Forbidden): error when creating "ClusterRole.yml": clusterroles.rbac.authorization.k8s.io "system:coredns" is forbidden: attempt to grant extra privileges: [PolicyRule{Resources:["endpoints"], APIGroups:[""], Verbs:["list"]} PolicyRule{Resources:["endpoints"], APIGroups:[""], Verbs:["watch"]} PolicyRule{Resources:["services"], APIGroups:[""], Verbs:["list"]} PolicyRule{Resources:["services"], APIGroups:[""], Verbs:["watch"]} PolicyRule{Resources:["pods"], APIGroups:[""], Verbs:["list"]} PolicyRule{Resources:["pods"], APIGroups:[""], Verbs:["watch"]} PolicyRule{Resources:["namespaces"], APIGroups:[""], Verbs:["list"]} PolicyRule{Resources:["namespaces"], APIGroups:[""], Verbs:["watch"]}] user=&{system:serviceaccount:kube-system:cluster-admin f809e079-93fc-11e8-8b85-525400546bcd [system:serviceaccounts system:serviceaccounts:kube-system system:authenticated] map[]} ownerrules=[PolicyRule{Resources:["selfsubjectaccessreviews"], APIGroups:["authorization.k8s.io"], Verbs:["create"]} PolicyRule{NonResourceURLs:["/api" "/api/*" "/apis" "/apis/*" "/healthz" "/swagger-2.0.0.pb-v1" "/swagger.json" "/swaggerapi" "/swaggerapi/*" "/version"], Verbs:["get"]}] ruleResolutionErrors=[]

下面是我用来开始的标志 apiserver :

  containers:
    - name: kube-apiserver
      image: quay.io/coreos/hyperkube:${K8S_VER}
      command:
        - /hyperkube
        - apiserver
        - --bind-address=0.0.0.0
        - --etcd-servers=${ETCD_ENDPOINTS}
        - --allow-privileged=true
        - --service-cluster-ip-range=${SERVICE_IP_RANGE}
        - --secure-port=443
        - --advertise-address=${ADVERTISE_IP}
        - --admission-control=NamespaceLifecycle,LimitRanger,ServiceAccount,DefaultStorageClass,ResourceQuota
        - --tls-cert-file=/etc/kubernetes/ssl/apiserver.pem
        - --tls-private-key-file=/etc/kubernetes/ssl/apiserver-key.pem
        - --client-ca-file=/etc/kubernetes/ssl/ca.pem
        - --service-account-key-file=/etc/kubernetes/ssl/apiserver-key.pem
        - --runtime-config=extensions/v1beta1/networkpolicies=true
        - --anonymous-auth=false
        - --authorization-mode=AlwaysAllow,RBAC,Node

以下是我用来生成 tls 证书:

根认证机构 :

openssl genrsa -out ca-key.pem 4096
openssl req -x509 -new -nodes -key ca-key.pem -days 3650 -out ca.pem -subj "/CN=kube-ca"

apiserver服务器 :

cat > openssl.cnf <<EOF
[req]
req_extensions = v3_req
distinguished_name = req_distinguished_name

[req_distinguished_name]

[v3_req]
basicConstraints = CA:FALSE
keyUsage = nonRepudiation, digitalSignature, keyEncipherment
subjectAltName = @alt_names

[alt_names]
DNS.1 = kubernetes
DNS.2 = kubernetes.default
DNS.3 = kubernetes.default.svc
DNS.4 = kubernetes.default.svc.cluster.local
DNS.5 = ${MASTER_LB_DNS}
IP.1 = ${K8S_SERVICE_IP}
IP.2 = ${MASTER_HOST}
EOF

openssl genrsa -out apiserver-key.pem 4096
openssl req -new -key apiserver-key.pem -out apiserver.csr -subj "/CN=kube-apiserver" -config openssl.cnf
openssl x509 -req -in apiserver.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial -out apiserver.pem -days 3650 -extensions v3_req -extfile openssl.cnf

群集管理 :

openssl genrsa -out cluster-admin-key.pem 4096
openssl req -new -key cluster-admin-key.pem -out cluster-admin.csr -subj "/CN=cluster-admin"
openssl x509 -req -in cluster-admin.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial -out cluster-admin.pem -days 3650

我希望这能给你更多的了解,我的系统出了什么问题。

编辑-2。

我注意到我的系统配置与@MarcinRomaszewicz所建议的略有不同,因此 命名空间 的 群集管理 ServiceAccount ,在我的情况下是在 kube-system 与 default 命名空间 :

$ kubectl delete clusterrolebinding cluster-admin-binding 
clusterrolebinding.rbac.authorization.k8s.io "cluster-admin-binding" deleted

$ kubectl create clusterrolebinding cluster-admin-binding \
 --clusterrole=cluster-admin --serviceaccount=kube-system:cluster-admin
clusterrolebinding.rbac.authorization.k8s.io "cluster-admin-binding" created

$ kubectl apply -f ClusterRole.yml 
clusterrole.rbac.authorization.k8s.io "system:coredns" created

但是我的证书还是不行。。。

编辑-3。

如评论中所建议的,为了 apiserver服务器 将用户识别为 群集管理 ,该用户证书中的主题行必须包含以下项: Subject: CN = cluster-admin, O = system:masters . 生成此类证书的一种方法如下:

openssl genrsa -out cluster-admin-key.pem 4096
openssl req -new -key cluster-admin-key.pem -out cluster-admin.csr -subj "/CN=cluster-admin/O=system:masters"
openssl x509 -req -in cluster-admin.csr -CA ca.pem -CAkey ca-key.pem -CAcreateserial -out cluster-admin.pem -days 3650

1 回复 | 直到 6 年前

Marcin Romaszewicz 6 年前

这里没有足够的信息来回答你的问题。

听起来您好像遇到了权限提升预防: https://kubernetes.io/docs/reference/access-authn-authz/rbac/#privilege-escalation-prevention-and-bootstrapping

这意味着您实际上不是作为集群管理员运行的。检查kubectl配置。例如,您可能以“admin”的身份运行,并被限制在特定的名称空间中。

(根据下面的评论进行编辑)

k8s的标识是由cluster.pem证书的内容建立的,而不是来自kubeconfig的用户名,因为该用户名仅在kubeconfig文件中有效。您的实际用户由该证书决定。

我看到您有一个名为cluster admin的服务帐户,但它不是“system:masters”的成员,因为组是身份验证系统的一个属性,用于对用户进行身份验证-您需要创建一个显式的群集角色绑定,以将您的群集管理服务帐户绑定到群集管理群集角色。

kubectl create clusterrolebinding cluster-admin-binding --clusterrole=cluster-admin --serviceaccount=default:cluster-admin

您应该看到clusterrole现在已与您的服务帐户绑定。

$ kubectl get clusterrolebinding cluster-admin-binding -o yaml
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRoleBinding
metadata:
  creationTimestamp: 2018-07-30T22:02:33Z
  name: cluster-admin-binding
  resourceVersion: "71152"
  selfLink: /apis/rbac.authorization.k8s.io/v1/clusterrolebindings/cluster-admin-binding
  uid: 42a2862c-9444-11e8-8b71-080027de17da
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: cluster-admin
subjects:
- kind: ServiceAccount
  name: cluster-admin
  namespace: default

请注意,在底部,绑定适用于“ServiceAccount”,而不是组。

您的服务帐户具有访问令牌,请使用该令牌而不是证书进行身份验证。我为自己创建了一个群集管理服务帐户,这就是我获取令牌的方式:

$ kubectl describe secret $(kubectl get secret | grep cluster-admin | awk '{print $1}')
Name:         cluster-admin-token-96vdz
Namespace:    default
Labels:       <none>
Annotations:  kubernetes.io/service-account.name=cluster-admin
              kubernetes.io/service-account.uid=f872f08b-9442-11e8-8b71-080027de17da

Type:  kubernetes.io/service-account-token

Data
====
token:      eyJhbGciOiJSUzI1NiIsImtpZCI6IiJ9.eyJpc3MiOiJrdWJlcm5ldGVzL3NlcnZpY2VhY2NvdW50Iiwia3ViZXJuZXRlcy5pby9zZXJ2aWNlYWNjb3VudC9uYW1lc3BhY2UiOiJkZWZhdWx0Iiwia3ViZXJuZXRlcy5pby9zZXJ2aWNlYWNjb3VudC9zZWNyZXQubmFtZSI6ImNsdXN0ZXItYWRtaW4tdG9rZW4tOTZ2ZHoiLCJrdWJlcm5ldGVzLmlvL3NlcnZpY2VhY2NvdW50L3NlcnZpY2UtYWNjb3VudC5uYW1lIjoiY2x1c3Rlci1hZG1pbiIsImt1YmVybmV0ZXMuaW8vc2VydmljZWFjY291bnQvc2VydmljZS1hY2NvdW50LnVpZCI6ImY4NzJmMDhiLTk0NDItMTFlOC04YjcxLTA4MDAyN2RlMTdkYSIsInN1YiI6InN5c3RlbTpzZXJ2aWNlYWNjb3VudDpkZWZhdWx0OmNsdXN0ZXItYWRtaW4ifQ.<signature snipped>
ca.crt:     1066 bytes
namespace:  7 bytes

更新kubeconfig以使用该令牌(而不是当前使用的证书)对自己进行身份验证,您应该作为该群集管理服务帐户成功进行身份验证。

(编辑2) 结果发现,用于向Kubernetes进行身份验证的证书没有任何关于该用户的身份声明。Kubernetes依赖于身份验证模块来对用户进行身份验证,在本例中,是基于证书的。它希望证书包含一个声明,通过将组织设置为“system:masters”,将用户放入“system:masters”组。

这里有很多活动的部分。这个问题与服务帐户或角色无关,而是与用户身份验证有关,后者非常不透明。