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 | 156 |
1 files changed, 156 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 index 8949d21b5..4ce989467 100644 --- a/vendor/github.com/containernetworking/plugins/pkg/ns/ns_linux.go +++ b/vendor/github.com/containernetworking/plugins/pkg/ns/ns_linux.go @@ -21,6 +21,7 @@ import ( "path" "runtime" "sync" + "syscall" "golang.org/x/sys/unix" ) @@ -147,3 +148,158 @@ func (ns *netNS) Set() error { return nil } + +type NetNS interface { + // Executes the passed closure in this object's network namespace, + // attempting to restore the original namespace before returning. + // However, since each OS thread can have a different network namespace, + // and Go's thread scheduling is highly variable, callers cannot + // guarantee any specific namespace is set unless operations that + // require that namespace are wrapped with Do(). Also, no code called + // from Do() should call runtime.UnlockOSThread(), or the risk + // of executing code in an incorrect namespace will be greater. See + // https://github.com/golang/go/wiki/LockOSThread for further details. + Do(toRun func(NetNS) error) error + + // Sets the current network namespace to this object's network namespace. + // Note that since Go's thread scheduling is highly variable, callers + // cannot guarantee the requested namespace will be the current namespace + // after this function is called; to ensure this wrap operations that + // require the namespace with Do() instead. + Set() error + + // Returns the filesystem path representing this object's network namespace + Path() string + + // Returns a file descriptor representing this object's network namespace + Fd() uintptr + + // Cleans up this instance of the network namespace; if this instance + // is the last user the namespace will be destroyed + Close() error +} + +type netNS struct { + file *os.File + mounted bool + closed bool +} + +// netNS implements the NetNS interface +var _ NetNS = &netNS{} + +const ( + // https://github.com/torvalds/linux/blob/master/include/uapi/linux/magic.h + NSFS_MAGIC = 0x6e736673 + PROCFS_MAGIC = 0x9fa0 +) + +type NSPathNotExistErr struct{ msg string } + +func (e NSPathNotExistErr) Error() string { return e.msg } + +type NSPathNotNSErr struct{ msg string } + +func (e NSPathNotNSErr) Error() string { return e.msg } + +func IsNSorErr(nspath string) error { + stat := syscall.Statfs_t{} + if err := syscall.Statfs(nspath, &stat); err != nil { + if os.IsNotExist(err) { + err = NSPathNotExistErr{msg: fmt.Sprintf("failed to Statfs %q: %v", nspath, err)} + } else { + err = fmt.Errorf("failed to Statfs %q: %v", nspath, err) + } + return err + } + + switch stat.Type { + case PROCFS_MAGIC, NSFS_MAGIC: + return nil + default: + return NSPathNotNSErr{msg: fmt.Sprintf("unknown FS magic on %q: %x", nspath, stat.Type)} + } +} + +// Returns an object representing the namespace referred to by @path +func GetNS(nspath string) (NetNS, error) { + err := IsNSorErr(nspath) + if err != nil { + return nil, err + } + + fd, err := os.Open(nspath) + if err != nil { + return nil, err + } + + return &netNS{file: fd}, nil +} + +func (ns *netNS) Path() string { + return ns.file.Name() +} + +func (ns *netNS) Fd() uintptr { + return ns.file.Fd() +} + +func (ns *netNS) errorIfClosed() error { + if ns.closed { + return fmt.Errorf("%q has already been closed", ns.file.Name()) + } + return nil +} + +func (ns *netNS) Do(toRun func(NetNS) error) error { + if err := ns.errorIfClosed(); err != nil { + return err + } + + containedCall := func(hostNS NetNS) error { + threadNS, err := GetCurrentNS() + if err != nil { + return fmt.Errorf("failed to open current netns: %v", err) + } + defer threadNS.Close() + + // switch to target namespace + if err = ns.Set(); err != nil { + return fmt.Errorf("error switching to ns %v: %v", ns.file.Name(), err) + } + defer threadNS.Set() // switch back + + return toRun(hostNS) + } + + // save a handle to current network namespace + hostNS, err := GetCurrentNS() + if err != nil { + return fmt.Errorf("Failed to open current namespace: %v", err) + } + defer hostNS.Close() + + var wg sync.WaitGroup + wg.Add(1) + + var innerError error + go func() { + defer wg.Done() + runtime.LockOSThread() + innerError = containedCall(hostNS) + }() + wg.Wait() + + return innerError +} + +// WithNetNSPath executes the passed closure under the given network +// namespace, restoring the original namespace afterwards. +func WithNetNSPath(nspath string, toRun func(NetNS) error) error { + ns, err := GetNS(nspath) + if err != nil { + return err + } + defer ns.Close() + return ns.Do(toRun) +} |