forked from containerd/cri
/
netns.go
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/
netns.go
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/*
Copyright 2017 The Kubernetes 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 sandbox
import (
"os"
"sync"
cnins "github.com/containernetworking/plugins/pkg/ns"
"github.com/docker/docker/pkg/symlink"
"github.com/pkg/errors"
"golang.org/x/sys/unix"
osinterface "github.com/containerd/cri/pkg/os"
)
// ErrClosedNetNS is the error returned when network namespace is closed.
var ErrClosedNetNS = errors.New("network namespace is closed")
// NetNS holds network namespace for sandbox
type NetNS struct {
sync.Mutex
ns cnins.NetNS
closed bool
restored bool
}
// NewNetNS creates a network namespace for the sandbox
func NewNetNS() (*NetNS, error) {
netns, err := cnins.NewNS()
if err != nil {
return nil, errors.Wrap(err, "failed to setup network namespace")
}
n := new(NetNS)
n.ns = netns
return n, nil
}
// LoadNetNS loads existing network namespace. It returns ErrClosedNetNS
// if the network namespace has already been closed.
func LoadNetNS(path string) (*NetNS, error) {
ns, err := cnins.GetNS(path)
if err != nil {
if _, ok := err.(cnins.NSPathNotExistErr); ok {
return nil, ErrClosedNetNS
}
if _, ok := err.(cnins.NSPathNotNSErr); ok {
// Do best effort cleanup.
os.RemoveAll(path) // nolint: errcheck
return nil, ErrClosedNetNS
}
return nil, errors.Wrap(err, "failed to load network namespace")
}
return &NetNS{ns: ns, restored: true}, nil
}
// Remove removes network namepace if it exists and not closed. Remove is idempotent,
// meaning it might be invoked multiple times and provides consistent result.
func (n *NetNS) Remove() error {
n.Lock()
defer n.Unlock()
if !n.closed {
err := n.ns.Close()
if err != nil {
return errors.Wrap(err, "failed to close network namespace")
}
n.closed = true
}
if n.restored {
path := n.ns.Path()
// Check netns existence.
if _, err := os.Stat(path); err != nil {
if os.IsNotExist(err) {
return nil
}
return errors.Wrap(err, "failed to stat netns")
}
path, err := symlink.FollowSymlinkInScope(path, "/")
if err != nil {
return errors.Wrap(err, "failed to follow symlink")
}
if err := osinterface.Unmount(path, unix.MNT_DETACH); err != nil && !os.IsNotExist(err) {
return errors.Wrap(err, "failed to umount netns")
}
if err := os.RemoveAll(path); err != nil {
return errors.Wrap(err, "failed to remove netns")
}
n.restored = false
}
return nil
}
// Closed checks whether the network namespace has been closed.
func (n *NetNS) Closed() bool {
n.Lock()
defer n.Unlock()
return n.closed && !n.restored
}
// GetPath returns network namespace path for sandbox container
func (n *NetNS) GetPath() string {
n.Lock()
defer n.Unlock()
return n.ns.Path()
}
// GetNs returns the network namespace handle
func (n *NetNS) GetNs() cnins.NetNS {
n.Lock()
defer n.Unlock()
return n.ns
}