k8s认证和鉴权

时间:2022-06-28 火线安全人气:0

背景

和master节点kube api-server通信的组件有很多，包括：

kubelet
calico
scheduler
kubectl
某些pod可能会和kube api-server通信

这些组件和api-server通信时用的是什么身份，可以操作哪些api资源呢？

本文使用的k8s集群是用kubekey搭建，命令是./kk create cluster --with-kubernetes v1.21.5 --with-kubesphere v3.2.1

kubectl的身份和权限

kubectl用的是什么身份？

kubectl默认会用到.kube/config配置，其中包含证书信息

root@ip-172-31-14-204:~# cat .kube/config
apiVersion: v1
...
users:
- name: kubernetes-admin
  user:
    client-certificate-data: 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
...

可以看到这个证书的CN是kubernetes-admin，O是system:masters。根据文档可以知道，这表示证书代表的用户是kubernetes-admin，用户组是system:masters。

root@ip-172-31-14-204:~# echo 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 | base64 -d | openssl x509  -noout -text
Certificate:
    ...
        Subject: O = system:masters, CN = kubernetes-admin

那这个证书代表的用户能操作哪些资源呢？

能操作哪些资源呢？

这个需要看"用户kubernetes-admin"、"用户组system:masters"在集群中绑定了什么"角色"。

可以看到它绑定了"ClusterRole/cluster-admin"，这个角色可以对所有资源做任意操作。

root@ip-172-31-14-204:~# kubectl get ClusterRoleBinding -A -o wide | grep system:masters
cluster-admin                                          ClusterRole/cluster-admin                                                          33h                                    system:masters

可以通过kubectl get ClusterRole/cluster-admin -o yaml查看角色的权限。

所以，.kube/config证书中代表的用户身份可以对所有资源做任意操作。

kube-scheduler的身份和权限

kube-scheduler用的是什么身份？

在master节点上查看scheduler进程，可以"大胆猜测"用的是/etc/kubernetes/scheduler.conf中的证书信息。

在我的k8s环境中，kube-scheduler是运行在pod中的，不过pod和宿主机的/etc/kubernetes/scheduler.conf文件是一样的

root@ip-172-31-14-33:~# ps aux|grep kube-scheduler
root     51897  0.2  0.7 753012 57736 ?        Ssl  May25   3:59 kube-scheduler --authentication-kubeconfig=/etc/kubernetes/scheduler.conf --authorization-kubeconfig=/etc/kubernetes/scheduler.conf --bind-address=0.0.0.0 --feature-gates=RotateKubeletServerCertificate=true,TTLAfterFinished=true,ExpandCSIVolumes=true,CSIStorageCapacity=true --kubeconfig=/etc/kubernetes/scheduler.conf --leader-elect=true --port=0

查看证书的Subject信息，可以看到用户是system:kube-scheduler

root@ip-172-31-14-33:~# echo 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 | base64 -d |openssl x509  -noout -text
Certificate:
    ...
        Subject: CN = system:kube-scheduler

可以看到"用户system:kube-scheduler"绑定了两个角色。

root@ip-172-31-14-33:~# kubectl get ClusterRoleBindings -o wide |grep system:kube-scheduler
system:kube-scheduler                                  ClusterRole/system:kube-scheduler                                                  31h   system:kube-scheduler
system:volume-scheduler                                ClusterRole/system:volume-scheduler                                                31h   system:kube-scheduler

kubelet的身份和权限

kubelet用的是什么身份？

root@ip-172-31-14-204:~# ps aux|grep kubelet
root     54396  7.7  2.8 1966128 113860 ?      Ssl  08:14  29:54 /usr/local/bin/kubelet ... --kubeconfig=/etc/kubernetes/kubelet.conf ...

在worker节点上可以看到kubelet进程参数，api-server信息在/etc/kubernetes/kubelet.conf文件中

可以看到是通过证书认证的

root@ip-172-31-14-204:/etc/kubernetes/manifests# cat /etc/kubernetes/kubelet.conf
apiVersion: v1
...
users:
- name: system:node:ip-172-31-14-33
  user:
    client-certificate: /var/lib/kubelet/pki/kubelet-client-current.pem
    client-key: /var/lib/kubelet/pki/kubelet-client-current.pem

查看证书的Subject信息，可以知道证书代表的"用户"是"system:node:ip-172-31-14-204"，"用户组"是"system:nodes"

root@ip-172-31-14-204:~# openssl x509 -in /var/lib/kubelet/pki/kubelet-client-current.pem -noout -text
Certificate:
    ...
        Subject: O = system:nodes, CN = system:node:ip-172-31-14-204

那这个kubelet的证书代表的用户能操作哪些资源呢？它可以用来像"集群管理员"那样创建pod吗？

kubelet能操作哪些资源？

按照之前流程，我们来看一下"用户system:node:ip-172-31-14-204"、"用户组system:nodes"在集群中绑定了什么"角色"。

root@ip-172-31-14-204:~# kubectl get ClusterRoleBinding -A|grep system:nodes
root@ip-172-31-14-204:~# kubectl get ClusterRoleBinding -A|grep "system:node:ip-172-31-14-204"
root@ip-172-31-14-204:~#

会发现"用户和用户组"没有绑定任何一个角色，这和kubectl、kube-scheduler就很不一样了。

在使用Node鉴权文档中提到，kube apiserver对kubelet的鉴权比较特殊。

当发现请求的用户在system:nodes组中，用户名是system:node:时，就限制这个请求只能做有限的操作，比如

读操作
- services
- pod
- 绑定到当前node的pod的secret、configMap
写操作（如果开启了NodeRestriction准入插件，就只能修改kubelet所在node的资源）
- 创建节点、修改节点状态
- 创建pod、pod状态

似乎如果没有开启NodeRestriction准入插件，就能让kubelet在任意node上创建pod。

红蓝对抗中，如果能让kubelet在任意node上创建pod，就能用来横移

文档中写到，这里的能力可能随着k8s版本变化而变化，以确保kubelet最小权限，默认安全。所以，kubelet到底能操作哪些资源，感觉还是来测试一下比较好，下面就来验证一下kubelet的权限。

验证kubelet的权限

我们先用kubelet配置文件覆盖kubectl的默认配置，然后就可以用kubectl命令来验证。

root@ip-172-31-14-204:~# mv .kube/config .kube/config.bak
root@ip-172-31-14-204:~# ps aux|grep kubele
root     59075  7.9  2.7 1956332 108712 ?      Ssl  03:37   2:51 /usr/local/bin/kubelet ... --kubeconfig=/etc/kubernetes/kubelet.conf ...
root@ip-172-31-14-204:~# cp /etc/kubernetes/kubelet.conf .kube/config

可以看到不能够创建pod

root@ip-172-31-14-204:~# kubectl run httpbin --image kennethreitz/httpbin
Error from server (Forbidden): pods "httpbin" is forbidden: pod does not have "kubernetes.io/config.mirror" annotation, node "ip-172-31-14-204" can only create mirror pod

查看pod信息是可以的

root@ip-172-31-14-204:~# kubectl get pods -A
NAMESPACE                      NAME                                               READY   STATUS      RESTARTS   AGE
default                        tail                                               1/1     Running     0          25h
kube-system                    calico-kube-controllers-846b5f484d-vzlhw           1/1     Running     0          27h
...
root@ip-172-31-14-204:~# kubectl describe pod devops-27558900-m69pc -n kubesphere-devops-system
Name:         devops-27558900-m69pc
...

查看secret和configMap是不允许的

root@ip-172-31-14-204:~# kubectl get secrets -A
Error from server (Forbidden): secrets is forbidden: User "system:node:ip-172-31-14-204" cannot list resource "secrets" in API group "" at the cluster scope: can only read namespaced object of this type
root@ip-172-31-14-204:~# kubectl get configmap
Error from server (Forbidden): configmaps is forbidden: User "system:node:ip-172-31-14-204" cannot list resource "configmaps" in API group "" in the namespace "default": No Object name found
root@ip-172-31-14-204:~#

小结：kubelet证书可以用来查看pod信息，不能创建pod、不能查看所有命名空间的secret和configMap。看起来和文档中的说明一致。

calico

calico用的是什么身份？

root@ip-172-31-14-204:~# cat /etc/cni/net.d/calico-kubeconfig
# Kubeconfig file for Calico CNI plugin. Installed by calico/node.
...
users:
- name: calico
  user:
    token: eyJhbGciOiJSUzI1NiIsImtpZCI6ImV6bEstc2QtRTNTaE1ySFg2SWdxMjY2aHpkVFBEWU56SGdfaVdZRXZ4YncifQ.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.mF1Yek_sSBa2nlQIbdJlEZtv3anjIUFPFpj8Ta8Zn1t6vxYEZjswbPxrw-90sbEVGR30GWytUjr3X1tmjWTP0fL9ltAPvcM0tRg6MoLuGdC2uZFbt-zfKFEn42Yme-NuVOKO3K2otgZNt0ym0gYRT41wLCqOuKLq-SHAkHdvIOZ1eVAu0OsN3ccgSFf2nsuBqbDphd4ShqRPNXl1m66UEDlb4WiPmuSPuzRmMiV706YbBPxMUzn9Ve4o4IfBbeBufp_edSWPPW763EGqZmI7qZg-78SUbtAJ6m8Qkq6TrDIcaJbI3Mrl4EsrnE3v3MGMOogfXXs3-yU-NZl3ilQt6Q
...

可以看到用的是token令牌。这个token令牌是一个jwt字符串，base64解码后的payload部分如下，可以看到"ServiceAccount"是calico-node，命名空间是kube-system

{"aud":["https://kubernetes.default.svc.cluster.local"],"exp":1685022900,"iat":1653486900,"iss":"https://kubernetes.default.svc.cluster.local","kubernetes.io":{"namespace":"kube-system","pod":{"name":"calico-node-qdtfb","uid":"87e8fc7d-2a89-4598-9d28-fd624b089603"},"serviceaccount":{"name":"calico-node","uid":"913750eb-bda4-4b2f-8167-46c991699add"},"warnafter":1653490507},"nbf":1653486900,"sub":"system:serviceaccount:kube-system:calico-nodeIn0

可以看到，这个"ServiceAccount"被绑定到了"ClusterRole/calico-node"角色。

root@ip-172-31-14-204:/home/ubuntu# kubectl get clusterrolebinding -o wide|grep kube-system/calico-node
calico-node                                            ClusterRole/calico-node                                                            34h                                                                                      kube-system/calico-node

pod

pod用的是什么身份？

大部分pod会挂载一个token在/var/run/secrets/kubernetes.io/serviceaccount/token位置，这个token也是一个jwt字符串。

root@ip-172-31-14-204:/home/ubuntu# kubectl exec -ti tail -- sh
/ # cat /var/run/secrets/kubernetes.io/serviceaccount/token
eyJhbGciOiJSUzI1NiIsImtpZCI6ImV6bEstc2QtRTNTaE1ySFg2SWdxMjY2aHpkVFBEWU56SGdfaVdZRXZ4YncifQ.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.L388ZKZWvHYf7Yvt6tA7t8k2QMYcsI9BDcYtoxAgOJiEiwf3LKFQmdH8KF4PnI0kjM3Bg80WztFznotwZqCwCNfXMVMl4_iLGHDAgVB3tsdv9ljZ9FUJbn52PD5aWHSWRqjpyQzv8_89dlnnbGQLHg4M8Ly4OkGuWUOnE1x6vgSa1MkjhrnrJEPnnJo5Fy_vyRdvO2A9iyGh7cC97Ns6WWFkeD7741wSkGkoNkZKqJTyfaa_KScprPiVPYuisi4HkYrP71NzZA_i34Dk-IsomySR4h3WWw_88-kfL_lWZ8PDu5NuVekZZ4xfIQjA6oDhXT_Hx4iIlhwVwgYuTW4V-g

base64解码后，payload中也能看到一个服务账号ServiceAccount，这个ServiceAccount也有可能和一个"角色"绑定。你可以动手查看一下自己的pod。

总结

k8s中"X509 客户证书"和"服务账号令牌"应该是身份认证最常见的两种方式，都能代表"用户"或"用户组"信息。

大部分的组件(包括scheduler、calico、kubectl、pod)鉴权都是依赖RBAC模型，也就是"用户或"用户组"绑定的"角色"规定了能访问哪些资源。

kubelet的鉴权比较特殊，是依赖Node鉴权模型。

用户认证文档中还提到api访问控制的其他方法。

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