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// Copyright 2020 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package inet
// Namespace represents a network namespace. See network_namespaces(7).
//
// +stateify savable
type Namespace struct {
namespaceRefs
// stack is the network stack implementation of this network namespace.
stack Stack `state:"nosave"`
// creator allows kernel to create new network stack for network namespaces.
// If nil, no networking will function if network is namespaced.
//
// At afterLoad(), creator will be used to create network stack. Stateify
// needs to wait for this field to be loaded before calling afterLoad().
creator NetworkStackCreator `state:"wait"`
// isRoot indicates whether this is the root network namespace.
isRoot bool
}
// NewRootNamespace creates the root network namespace, with creator
// allowing new network namespaces to be created. If creator is nil, no
// networking will function if the network is namespaced.
func NewRootNamespace(stack Stack, creator NetworkStackCreator) *Namespace {
n := &Namespace{
stack: stack,
creator: creator,
isRoot: true,
}
n.InitRefs()
return n
}
// NewNamespace creates a new network namespace from the root.
func NewNamespace(root *Namespace) *Namespace {
n := &Namespace{
creator: root.creator,
}
n.init()
n.InitRefs()
return n
}
// DecRef decrements the Namespace's refcount.
func (n *Namespace) DecRef() {
n.namespaceRefs.DecRef(func() {
if s := n.Stack(); s != nil {
s.Destroy()
}
})
}
// Stack returns the network stack of n. Stack may return nil if no network
// stack is configured.
func (n *Namespace) Stack() Stack {
return n.stack
}
// IsRoot returns whether n is the root network namespace.
func (n *Namespace) IsRoot() bool {
return n.isRoot
}
// RestoreRootStack restores the root network namespace with stack. This should
// only be called when restoring kernel.
func (n *Namespace) RestoreRootStack(stack Stack) {
if !n.isRoot {
panic("RestoreRootStack can only be called on root network namespace")
}
if n.stack != nil {
panic("RestoreRootStack called after a stack has already been set")
}
n.stack = stack
}
func (n *Namespace) init() {
// Root network namespace will have stack assigned later.
if n.isRoot {
return
}
if n.creator != nil {
var err error
n.stack, err = n.creator.CreateStack()
if err != nil {
panic(err)
}
}
}
// afterLoad is invoked by stateify.
func (n *Namespace) afterLoad() {
n.init()
}
// NetworkStackCreator allows new instances of a network stack to be created. It
// is used by the kernel to create new network namespaces when requested.
type NetworkStackCreator interface {
// CreateStack creates a new network stack for a network namespace.
CreateStack() (Stack, error)
}
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