133 lines
3.6 KiB
Go
133 lines
3.6 KiB
Go
/*
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Copyright 2017 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 sandbox
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import (
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"os"
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"sync"
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cnins "github.com/containernetworking/plugins/pkg/ns"
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"github.com/docker/docker/pkg/symlink"
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"github.com/pkg/errors"
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osinterface "github.com/containerd/cri/pkg/os"
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)
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// The NetNS library assumes only containerd manages the lifecycle of the
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// network namespace mount. The only case that netns will be unmounted by
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// someone else is node reboot.
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// If this assumption is broken, NetNS won't be aware of the external
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// unmount, and there will be a state mismatch.
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// TODO(random-liu): Don't cache state, always load from the system.
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// ErrClosedNetNS is the error returned when network namespace is closed.
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var ErrClosedNetNS = errors.New("network namespace is closed")
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// NetNS holds network namespace for sandbox
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type NetNS struct {
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sync.Mutex
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ns cnins.NetNS
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closed bool
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restored bool
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}
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// NewNetNS creates a network namespace for the sandbox
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func NewNetNS() (*NetNS, error) {
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netns, err := cnins.NewNS()
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if err != nil {
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return nil, errors.Wrap(err, "failed to setup network namespace")
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}
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n := new(NetNS)
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n.ns = netns
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return n, nil
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}
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// LoadNetNS loads existing network namespace. It returns ErrClosedNetNS
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// if the network namespace has already been closed.
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func LoadNetNS(path string) (*NetNS, error) {
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ns, err := cnins.GetNS(path)
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if err != nil {
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if _, ok := err.(cnins.NSPathNotExistErr); ok {
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return nil, ErrClosedNetNS
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}
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if _, ok := err.(cnins.NSPathNotNSErr); ok {
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// Do best effort cleanup.
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os.RemoveAll(path) // nolint: errcheck
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return nil, ErrClosedNetNS
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}
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return nil, errors.Wrap(err, "failed to load network namespace")
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}
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return &NetNS{ns: ns, restored: true}, nil
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}
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// Remove removes network namepace if it exists and not closed. Remove is idempotent,
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// meaning it might be invoked multiple times and provides consistent result.
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func (n *NetNS) Remove() error {
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n.Lock()
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defer n.Unlock()
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if !n.closed {
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err := n.ns.Close()
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if err != nil {
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return errors.Wrap(err, "failed to close network namespace")
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}
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n.closed = true
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}
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if n.restored {
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path := n.ns.Path()
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// Check netns existence.
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if _, err := os.Stat(path); err != nil {
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if os.IsNotExist(err) {
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return nil
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}
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return errors.Wrap(err, "failed to stat netns")
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}
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path, err := symlink.FollowSymlinkInScope(path, "/")
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if err != nil {
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return errors.Wrap(err, "failed to follow symlink")
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}
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if err := osinterface.Unmount(path); err != nil && !os.IsNotExist(err) {
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return errors.Wrap(err, "failed to umount netns")
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}
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if err := os.RemoveAll(path); err != nil {
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return errors.Wrap(err, "failed to remove netns")
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}
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n.restored = false
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}
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return nil
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}
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// Closed checks whether the network namespace has been closed.
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func (n *NetNS) Closed() bool {
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n.Lock()
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defer n.Unlock()
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return n.closed && !n.restored
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}
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// GetPath returns network namespace path for sandbox container
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func (n *NetNS) GetPath() string {
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n.Lock()
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defer n.Unlock()
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return n.ns.Path()
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}
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// GetNs returns the network namespace handle
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func (n *NetNS) GetNs() cnins.NetNS {
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n.Lock()
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defer n.Unlock()
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return n.ns
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}
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