k8s支持Capability机制

微信扫一扫,分享到朋友圈

k8s支持Capability机制

Docker Container Capabilities

在docker run命令中,我们可以通过 --cap-add
--cap-drop
来给容器添加 linux Capabilities
。下面表格中的列出的Capabilities是docker默认给容器添加的,用户可以通过 --cap-drop
去除其中一个或者多个。

Docker’s capabilities Linux capabilities Capability Description
SETPCAP CAP_SETPCAP Modify process capabilities.
MKNOD CAP_MKNOD Create special files using mknod(2).
AUDIT_WRITE CAP_AUDIT_WRITE Write records to kernel auditing log.
CHOWN CAP_CHOWN Make arbitrary changes to file UIDs and GIDs (see chown(2)).
NET_RAW CAP_NET_RAW Use RAW and PACKET sockets.
DAC_OVERRIDE CAP_DAC_OVERRIDE Bypass file read, write, and execute permission checks.
FOWNER CAP_FOWNER Bypass permission checks on operations that normally require the file system UID of the process to match the UID of the file.
FSETID CAP_FSETID Don’t clear set-user-ID and set-group-ID permission bits when a file is modified.
KILL CAP_KILL Bypass permission checks for sending signals.
SETGID CAP_SETGID Make arbitrary manipulations of process GIDs and supplementary GID list.
SETUID CAP_SETUID Make arbitrary manipulations of process UIDs.
NET_BIND_SERVICE CAP_NET_BIND_SERVICE Bind a socket to internet domain privileged ports (port numbers less than 1024).
SYS_CHROOT CAP_SYS_CHROOT Use chroot(2), change root directory.
SETFCAP CAP_SETFCAP Set file capabilities.

下面表格中列出的 Capabilities
docker
默认删除的 Capabilities
,用户可以通过 --cap-add
添加其中一个或者多个。

Docker’s capabilities Linux capabilities Capability Description
SYS_MODULE CAP_SYS_MODULE Load and unload kernel modules.
SYS_RAWIO CAP_SYS_RAWIO Perform I/O port operations (iopl(2) and ioperm(2)).
SYS_PACCT CAP_SYS_PACCT Use acct(2), switch process accounting on or off.
SYS_ADMIN CAP_SYS_ADMIN Perform a range of system administration operations.
SYS_NICE CAP_SYS_NICE Raise process nice value (nice(2), setpriority(2)) and change the nice value for arbitrary processes.
SYS_RESOURCE CAP_SYS_RESOURCE Override resource Limits.
SYS_TIME CAP_SYS_TIME Set system clock (settimeofday(2), stime(2), adjtimex(2)); set real-time (hardware) clock.
SYS_TTY_CONFIG CAP_SYS_TTY_CONFIG Use vhangup(2); employ various privileged ioctl(2) operations on virtual terminals.
AUDIT_CONTROL CAP_AUDIT_CONTROL Enable and disable kernel auditing; change auditing filter rules; retrieve auditing status and filtering rules.
MAC_OVERRIDE CAP_MAC_OVERRIDE Allow MAC configuration or state changes. Implemented for the Smack LSM.
MAC_ADMIN CAP_MAC_ADMIN Override Mandatory Access Control (MAC). Implemented for the Smack Linux Security Module (LSM).
NET_ADMIN CAP_NET_ADMIN Perform various network-related operations.
SYSLOG CAP_SYSLOG Perform privileged syslog(2) operations.
DAC_READ_SEARCH CAP_DAC_READ_SEARCH Bypass file read permission checks and directory read and execute permission checks.
LINUX_IMMUTABLE CAP_LINUX_IMMUTABLE Set the FS_APPEND_FL and FS_IMMUTABLE_FL i-node flags.
NET_BROADCAST CAP_NET_BROADCAST Make socket broadcasts, and listen to multicasts.
IPC_LOCK CAP_IPC_LOCK Lock memory (mlock(2), mlockall(2), mmap(2), shmctl(2)).
IPC_OWNER CAP_IPC_OWNER Bypass permission checks for operations on System V IPC objects.
SYS_PTRACE CAP_SYS_PTRACE Trace arbitrary processes using ptrace(2).
SYS_BOOT CAP_SYS_BOOT Use reboot(2) and kexec_load(2), reboot and load a new kernel for later execution.
LEASE CAP_LEASE Establish leases on arbitrary files (see fcntl(2)).
WAKE_ALARM CAP_WAKE_ALARM Trigger something that will wake up the system.
BLOCK_SUSPEND CAP_BLOCK_SUSPEND Employ features that can block system suspend.

比如,我们可以通过给给容器add NET_ADMIN Capability,使得我们可以对network interface进行modify,对应的docker run命令如下:

$ docker run -it --rm --cap-add=NET_ADMIN ubuntu:14.04 ip link add dummy0 type dummy

Kubernetes对Pod的定义中,用户可以 add/drop Capabilities
Pod.spec.containers.sercurityContext.capabilities
中添加要add的Capabilities list和drop的Capabilities list。

[root@paasm1 ~]# cat pause.yaml
apiVersion: v1
kind: Pod
metadata:
name: pause
spec:
containers:
- name:  pause
image: registry.paas/cmss/busybox
command: [ "sh", "-c", "sleep 1h" ]
[root@paasm1 ~]# kubectl create -f pause.yaml
pod/pause created
[root@paasm1 ~]# kubectl get pod
NAME                                        READY   STATUS             RESTARTS   AGE
docker-paasn1                               0/1     Pending            0          19d
independent-jaguar-nginx-647f7998cd-gstrj   0/1     ImagePullBackOff   0          45h
pause                                       1/1     Running            0          27s
r00tf0rm3                                   0/1     ErrImagePull       0          19d
[root@paasm1 ~]# kubectl exec pause -it sh
/ # vi
/ # date
Fri May 22 06:44:13 UTC 2020
/ # date -s 09:09
date: can't set date: Operation not permitted
Fri May 22 09:09:00 UTC 2020
/ # [root@paasm1 ~]#

Pod pause不能修改系统时间

[root@paasm1 ~]# cat pause1.yaml
apiVersion: v1
kind: Pod
metadata:
name: pause1
spec:
containers:
- name:  pause1
image: registry.paas/cmss/busybox
command: [ "sh", "-c", "sleep 1h" ]
securityContext:
capabilities:
add: ["NET_ADMIN","SYS_TIME"]
[root@paasm1 ~]# kubectl create -f pause1.yaml
pod/pause1 created
[root@paasm1 ~]# kubectl get pod
NAME                                        READY   STATUS             RESTARTS   AGE
docker-paasn1                               0/1     Pending            0          19d
independent-jaguar-nginx-647f7998cd-gstrj   0/1     ImagePullBackOff   0          45h
pause                                       1/1     Running            0          7m42s
pause1                                      1/1     Running            0          30s
r00tf0rm3                                   0/1     ErrImagePull       0          19d
[root@paasm1 ~]# kubectl exec pause1 -it sh
/ # date
Fri May 22 01:13:12 UTC 2020
/ # date -s 20:20
Fri May 22 20:20:00 UTC 2020
/ # date
Fri May 22 20:20:01 UTC 2020
/ # [root@paasm1 ~]#

Pod pause1可以修改系统时间

微信扫一扫,分享到朋友圈

k8s支持Capability机制

Spring boot 整合 KAFKA 消息队列

上一篇

CI实现方法之--Gitlba+Drone 荐

下一篇

你也可能喜欢

k8s支持Capability机制

长按储存图像,分享给朋友