4bee884fae
CNI is developed by more than just CoreOS, Inc and the copyright is retained by all CNI contributors (for their respective contributed code).
93 lines
2.6 KiB
Go
93 lines
2.6 KiB
Go
// Copyright 2015 CNI authors
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package ns
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import (
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"fmt"
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"os"
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"runtime"
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"syscall"
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)
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var setNsMap = map[string]uintptr{
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"386": 346,
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"amd64": 308,
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"arm": 374,
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}
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// SetNS sets the network namespace on a target file.
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func SetNS(f *os.File, flags uintptr) error {
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if runtime.GOOS != "linux" {
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return fmt.Errorf("unsupported OS: %s", runtime.GOOS)
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}
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trap, ok := setNsMap[runtime.GOARCH]
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if !ok {
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return fmt.Errorf("unsupported arch: %s", runtime.GOARCH)
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}
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_, _, err := syscall.RawSyscall(trap, f.Fd(), flags, 0)
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if err != 0 {
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return err
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}
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return nil
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}
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// WithNetNSPath executes the passed closure under the given network
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// namespace, restoring the original namespace afterwards.
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// Changing namespaces must be done on a goroutine that has been
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// locked to an OS thread. If lockThread arg is true, this function
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// locks the goroutine prior to change namespace and unlocks before
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// returning
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func WithNetNSPath(nspath string, lockThread bool, f func(*os.File) error) error {
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ns, err := os.Open(nspath)
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if err != nil {
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return fmt.Errorf("Failed to open %v: %v", nspath, err)
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}
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defer ns.Close()
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return WithNetNS(ns, lockThread, f)
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}
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// WithNetNS executes the passed closure under the given network
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// namespace, restoring the original namespace afterwards.
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// Changing namespaces must be done on a goroutine that has been
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// locked to an OS thread. If lockThread arg is true, this function
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// locks the goroutine prior to change namespace and unlocks before
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// returning
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func WithNetNS(ns *os.File, lockThread bool, f func(*os.File) error) error {
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if lockThread {
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runtime.LockOSThread()
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defer runtime.UnlockOSThread()
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}
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// save a handle to current (host) network namespace
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thisNS, err := os.Open("/proc/self/ns/net")
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if err != nil {
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return fmt.Errorf("Failed to open /proc/self/ns/net: %v", err)
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}
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defer thisNS.Close()
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if err = SetNS(ns, syscall.CLONE_NEWNET); err != nil {
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return fmt.Errorf("Error switching to ns %v: %v", ns.Name(), err)
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}
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if err = f(thisNS); err != nil {
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return err
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}
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// switch back
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return SetNS(thisNS, syscall.CLONE_NEWNET)
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}
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