diff options
Diffstat (limited to 'vendor/github.com/containernetworking/plugins/pkg/ns/ns_linux.go')
-rw-r--r-- | vendor/github.com/containernetworking/plugins/pkg/ns/ns_linux.go | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/vendor/github.com/containernetworking/plugins/pkg/ns/ns_linux.go b/vendor/github.com/containernetworking/plugins/pkg/ns/ns_linux.go new file mode 100644 index 000000000..8949d21b5 --- /dev/null +++ b/vendor/github.com/containernetworking/plugins/pkg/ns/ns_linux.go @@ -0,0 +1,149 @@ +// Copyright 2015-2017 CNI 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 ns + +import ( + "crypto/rand" + "fmt" + "os" + "path" + "runtime" + "sync" + + "golang.org/x/sys/unix" +) + +// Returns an object representing the current OS thread's network namespace +func GetCurrentNS() (NetNS, error) { + return GetNS(getCurrentThreadNetNSPath()) +} + +func getCurrentThreadNetNSPath() string { + // /proc/self/ns/net returns the namespace of the main thread, not + // of whatever thread this goroutine is running on. Make sure we + // use the thread's net namespace since the thread is switching around + return fmt.Sprintf("/proc/%d/task/%d/ns/net", os.Getpid(), unix.Gettid()) +} + +// Creates a new persistent network namespace and returns an object +// representing that namespace, without switching to it +func NewNS() (NetNS, error) { + const nsRunDir = "/var/run/netns" + + b := make([]byte, 16) + _, err := rand.Reader.Read(b) + if err != nil { + return nil, fmt.Errorf("failed to generate random netns name: %v", err) + } + + err = os.MkdirAll(nsRunDir, 0755) + if err != nil { + return nil, err + } + + // create an empty file at the mount point + nsName := fmt.Sprintf("cni-%x-%x-%x-%x-%x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:]) + nsPath := path.Join(nsRunDir, nsName) + mountPointFd, err := os.Create(nsPath) + if err != nil { + return nil, err + } + mountPointFd.Close() + + // Ensure the mount point is cleaned up on errors; if the namespace + // was successfully mounted this will have no effect because the file + // is in-use + defer os.RemoveAll(nsPath) + + var wg sync.WaitGroup + wg.Add(1) + + // do namespace work in a dedicated goroutine, so that we can safely + // Lock/Unlock OSThread without upsetting the lock/unlock state of + // the caller of this function + var fd *os.File + go (func() { + defer wg.Done() + runtime.LockOSThread() + + var origNS NetNS + origNS, err = GetNS(getCurrentThreadNetNSPath()) + if err != nil { + return + } + defer origNS.Close() + + // create a new netns on the current thread + err = unix.Unshare(unix.CLONE_NEWNET) + if err != nil { + return + } + defer origNS.Set() + + // bind mount the new netns from the current thread onto the mount point + err = unix.Mount(getCurrentThreadNetNSPath(), nsPath, "none", unix.MS_BIND, "") + if err != nil { + return + } + + fd, err = os.Open(nsPath) + if err != nil { + return + } + })() + wg.Wait() + + if err != nil { + unix.Unmount(nsPath, unix.MNT_DETACH) + return nil, fmt.Errorf("failed to create namespace: %v", err) + } + + return &netNS{file: fd, mounted: true}, nil +} + +func (ns *netNS) Close() error { + if err := ns.errorIfClosed(); err != nil { + return err + } + + if err := ns.file.Close(); err != nil { + return fmt.Errorf("Failed to close %q: %v", ns.file.Name(), err) + } + ns.closed = true + + if ns.mounted { + if err := unix.Unmount(ns.file.Name(), unix.MNT_DETACH); err != nil { + return fmt.Errorf("Failed to unmount namespace %s: %v", ns.file.Name(), err) + } + if err := os.RemoveAll(ns.file.Name()); err != nil { + return fmt.Errorf("Failed to clean up namespace %s: %v", ns.file.Name(), err) + } + ns.mounted = false + } + + return nil +} + +func (ns *netNS) Set() error { + if err := ns.errorIfClosed(); err != nil { + return err + } + + if err := unix.Setns(int(ns.Fd()), unix.CLONE_NEWNET); err != nil { + return fmt.Errorf("Error switching to ns %v: %v", ns.file.Name(), err) + } + + return nil +} |