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105 lines
3.6 KiB
Go
105 lines
3.6 KiB
Go
/*
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Copyright 2023 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package sysctl
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import (
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"strings"
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)
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// Namespace represents a kernel namespace name.
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type Namespace string
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const (
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// refer to https://man7.org/linux/man-pages/man7/ipc_namespaces.7.html
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// the Linux IPC namespace
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IPCNamespace = Namespace("IPC")
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// refer to https://man7.org/linux/man-pages/man7/network_namespaces.7.html
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// the network namespace
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NetNamespace = Namespace("Net")
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// the zero value if no namespace is known
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UnknownNamespace = Namespace("")
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)
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var nameToNamespace = map[string]Namespace{
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// kernel semaphore parameters: SEMMSL, SEMMNS, SEMOPM, and SEMMNI.
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"kernel.sem": IPCNamespace,
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// kernel shared memory limits include shmall, shmmax, shmmni, and shm_rmid_forced.
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"kernel.shmall": IPCNamespace,
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"kernel.shmmax": IPCNamespace,
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"kernel.shmmni": IPCNamespace,
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"kernel.shm_rmid_forced": IPCNamespace,
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// make backward compatibility to know the namespace of kernel.shm*
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"kernel.shm": IPCNamespace,
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// kernel messages include msgmni, msgmax and msgmnb.
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"kernel.msgmax": IPCNamespace,
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"kernel.msgmnb": IPCNamespace,
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"kernel.msgmni": IPCNamespace,
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// make backward compatibility to know the namespace of kernel.msg*
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"kernel.msg": IPCNamespace,
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}
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var prefixToNamespace = map[string]Namespace{
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"net": NetNamespace,
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// mqueue filesystem provides the necessary kernel features to enable the creation
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// of a user space library that implements the POSIX message queues API.
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"fs.mqueue": IPCNamespace,
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}
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// namespaceOf returns the namespace of the Linux kernel for a sysctl, or
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// unknownNamespace if the sysctl is not known to be namespaced.
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// The second return is prefixed bool.
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// It returns true if the key is prefixed with a key in the prefix map
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func namespaceOf(val string) Namespace {
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if ns, found := nameToNamespace[val]; found {
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return ns
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}
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for p, ns := range prefixToNamespace {
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if strings.HasPrefix(val, p+".") {
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return ns
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}
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}
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return UnknownNamespace
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}
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// GetNamespace extracts information from a sysctl string. It returns:
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// 1. The sysctl namespace, which can be one of the following: IPC, Net, or unknown.
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// 2. sysctlOrPrefix: the prefix of the sysctl parameter until the first '*'.
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// If there is no '*', it will be the original string.
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// 3. 'prefixed' is set to true if the sysctl parameter contains '*' or it is in the prefixToNamespace key list, in most cases, it is a suffix *.
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//
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// For example, if the input sysctl is 'net.ipv6.neigh.*', GetNamespace will return:
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// - The Net namespace
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// - The sysctlOrPrefix as 'net.ipv6.neigh'
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// - 'prefixed' set to true
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//
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// For the input sysctl 'net.ipv6.conf.all.disable_ipv6', GetNamespace will return:
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// - The Net namespace
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// - The sysctlOrPrefix as 'net.ipv6.conf.all.disable_ipv6'
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// - 'prefixed' set to false.
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func GetNamespace(sysctl string) (ns Namespace, sysctlOrPrefix string, prefixed bool) {
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sysctlOrPrefix = NormalizeName(sysctl)
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firstIndex := strings.IndexAny(sysctlOrPrefix, "*")
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if firstIndex != -1 {
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sysctlOrPrefix = sysctlOrPrefix[:firstIndex]
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prefixed = true
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}
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ns = namespaceOf(sysctlOrPrefix)
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return
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}
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