// Copyright 2018 The gVisor 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 boot import ( "errors" "fmt" "os" "path" "syscall" specs "github.com/opencontainers/runtime-spec/specs-go" "gvisor.dev/gvisor/pkg/control/server" "gvisor.dev/gvisor/pkg/log" "gvisor.dev/gvisor/pkg/sentry/control" "gvisor.dev/gvisor/pkg/sentry/fs" "gvisor.dev/gvisor/pkg/sentry/kernel" "gvisor.dev/gvisor/pkg/sentry/socket/epsocket" "gvisor.dev/gvisor/pkg/sentry/state" "gvisor.dev/gvisor/pkg/sentry/time" "gvisor.dev/gvisor/pkg/sentry/watchdog" "gvisor.dev/gvisor/pkg/tcpip/stack" "gvisor.dev/gvisor/pkg/urpc" ) const ( // ContainerCheckpoint checkpoints a container. ContainerCheckpoint = "containerManager.Checkpoint" // ContainerCreate creates a container. ContainerCreate = "containerManager.Create" // ContainerDestroy is used to stop a non-root container and free all // associated resources in the sandbox. ContainerDestroy = "containerManager.Destroy" // ContainerEvent is the URPC endpoint for getting stats about the // container used by "runsc events". ContainerEvent = "containerManager.Event" // ContainerExecuteAsync is the URPC endpoint for executing a command in a // container.. ContainerExecuteAsync = "containerManager.ExecuteAsync" // ContainerPause pauses the container. ContainerPause = "containerManager.Pause" // ContainerProcesses is the URPC endpoint for getting the list of // processes running in a container. ContainerProcesses = "containerManager.Processes" // ContainerRestore restores a container from a statefile. ContainerRestore = "containerManager.Restore" // ContainerResume unpauses the paused container. ContainerResume = "containerManager.Resume" // ContainerSignal is used to send a signal to a container. ContainerSignal = "containerManager.Signal" // ContainerSignalProcess is used to send a signal to a particular // process in a container. ContainerSignalProcess = "containerManager.SignalProcess" // ContainerStart is the URPC endpoint for running a non-root container // within a sandbox. ContainerStart = "containerManager.Start" // ContainerWait is used to wait on the init process of the container // and return its ExitStatus. ContainerWait = "containerManager.Wait" // ContainerWaitPID is used to wait on a process with a certain PID in // the sandbox and return its ExitStatus. ContainerWaitPID = "containerManager.WaitPID" // NetworkCreateLinksAndRoutes is the URPC endpoint for creating links // and routes in a network stack. NetworkCreateLinksAndRoutes = "Network.CreateLinksAndRoutes" // RootContainerStart is the URPC endpoint for starting a new sandbox // with root container. RootContainerStart = "containerManager.StartRoot" // SandboxStacks collects sandbox stacks for debugging. SandboxStacks = "debug.Stacks" ) // Profiling related commands (see pprof.go for more details). const ( StartCPUProfile = "Profile.StartCPUProfile" StopCPUProfile = "Profile.StopCPUProfile" HeapProfile = "Profile.HeapProfile" StartTrace = "Profile.StartTrace" StopTrace = "Profile.StopTrace" ) // Logging related commands (see logging.go for more details). const ( ChangeLogging = "Logging.Change" ) // ControlSocketAddr generates an abstract unix socket name for the given ID. func ControlSocketAddr(id string) string { return fmt.Sprintf("\x00runsc-sandbox.%s", id) } // controller holds the control server, and is used for communication into the // sandbox. type controller struct { // srv is the control server. srv *server.Server // manager holds the containerManager methods. manager *containerManager } // newController creates a new controller. The caller must call // controller.srv.StartServing() to start the controller. func newController(fd int, l *Loader) (*controller, error) { srv, err := server.CreateFromFD(fd) if err != nil { return nil, err } manager := &containerManager{ startChan: make(chan struct{}), startResultChan: make(chan error), l: l, } srv.Register(manager) if eps, ok := l.k.NetworkStack().(*epsocket.Stack); ok { net := &Network{ Stack: eps.Stack, } srv.Register(net) } srv.Register(&debug{}) srv.Register(&control.Logging{}) if l.conf.ProfileEnable { srv.Register(&control.Profile{}) } return &controller{ srv: srv, manager: manager, }, nil } // containerManager manages sandboes containers. type containerManager struct { // startChan is used to signal when the root container process should // be started. startChan chan struct{} // startResultChan is used to signal when the root container has // started. Any errors encountered during startup will be sent to the // channel. A nil value indicates success. startResultChan chan error // l is the loader that creates containers and sandboxes. l *Loader } // StartRoot will start the root container process. func (cm *containerManager) StartRoot(cid *string, _ *struct{}) error { log.Debugf("containerManager.StartRoot %q", *cid) // Tell the root container to start and wait for the result. cm.startChan <- struct{}{} if err := <-cm.startResultChan; err != nil { return fmt.Errorf("starting sandbox: %v", err) } return nil } // Processes retrieves information about processes running in the sandbox. func (cm *containerManager) Processes(cid *string, out *[]*control.Process) error { log.Debugf("containerManager.Processes: %q", *cid) return control.Processes(cm.l.k, *cid, out) } // Create creates a container within a sandbox. func (cm *containerManager) Create(cid *string, _ *struct{}) error { log.Debugf("containerManager.Create: %q", *cid) return cm.l.createContainer(*cid) } // StartArgs contains arguments to the Start method. type StartArgs struct { // Spec is the spec of the container to start. Spec *specs.Spec // Config is the runsc-specific configuration for the sandbox. Conf *Config // CID is the ID of the container to start. CID string // FilePayload contains, in order: // * stdin, stdout, and stderr. // * the file descriptor over which the sandbox will // request files from its root filesystem. urpc.FilePayload } // Start runs a created container within a sandbox. func (cm *containerManager) Start(args *StartArgs, _ *struct{}) error { log.Debugf("containerManager.Start: %+v", args) // Validate arguments. if args == nil { return errors.New("start missing arguments") } if args.Spec == nil { return errors.New("start arguments missing spec") } if args.Conf == nil { return errors.New("start arguments missing config") } if args.CID == "" { return errors.New("start argument missing container ID") } // Prevent CIDs containing ".." from confusing the sentry when creating // /containers/<cid> directory. // TODO(b/129293409): Once we have multiple independent roots, this // check won't be necessary. if path.Clean(args.CID) != args.CID { return fmt.Errorf("container ID shouldn't contain directory traversals such as \"..\": %q", args.CID) } if len(args.FilePayload.Files) < 4 { return fmt.Errorf("start arguments must contain stdin, stderr, and stdout followed by at least one file for the container root gofer") } err := cm.l.startContainer(args.Spec, args.Conf, args.CID, args.FilePayload.Files) if err != nil { log.Debugf("containerManager.Start failed %q: %+v: %v", args.CID, args, err) return err } log.Debugf("Container %q started", args.CID) return nil } // Destroy stops a container if it is still running and cleans up its // filesystem. func (cm *containerManager) Destroy(cid *string, _ *struct{}) error { log.Debugf("containerManager.destroy %q", *cid) return cm.l.destroyContainer(*cid) } // ExecuteAsync starts running a command on a created or running sandbox. It // returns the PID of the new process. func (cm *containerManager) ExecuteAsync(args *control.ExecArgs, pid *int32) error { log.Debugf("containerManager.ExecuteAsync: %+v", args) tgid, err := cm.l.executeAsync(args) if err != nil { log.Debugf("containerManager.ExecuteAsync failed: %+v: %v", args, err) return err } *pid = int32(tgid) return nil } // Checkpoint pauses a sandbox and saves its state. func (cm *containerManager) Checkpoint(o *control.SaveOpts, _ *struct{}) error { log.Debugf("containerManager.Checkpoint") state := control.State{ Kernel: cm.l.k, Watchdog: cm.l.watchdog, } return state.Save(o, nil) } // Pause suspends a container. func (cm *containerManager) Pause(_, _ *struct{}) error { log.Debugf("containerManager.Pause") cm.l.k.Pause() return nil } // RestoreOpts contains options related to restoring a container's file system. type RestoreOpts struct { // FilePayload contains the state file to be restored, followed by the // platform device file if necessary. urpc.FilePayload // SandboxID contains the ID of the sandbox. SandboxID string } // Restore loads a container from a statefile. // The container's current kernel is destroyed, a restore environment is // created, and the kernel is recreated with the restore state file. The // container then sends the signal to start. func (cm *containerManager) Restore(o *RestoreOpts, _ *struct{}) error { log.Debugf("containerManager.Restore") var specFile, deviceFile *os.File switch numFiles := len(o.FilePayload.Files); numFiles { case 2: // The device file is donated to the platform. // Can't take ownership away from os.File. dup them to get a new FD. fd, err := syscall.Dup(int(o.FilePayload.Files[1].Fd())) if err != nil { return fmt.Errorf("failed to dup file: %v", err) } deviceFile = os.NewFile(uintptr(fd), "platform device") fallthrough case 1: specFile = o.FilePayload.Files[0] case 0: return fmt.Errorf("at least one file must be passed to Restore") default: return fmt.Errorf("at most two files may be passed to Restore") } // Pause the kernel while we build a new one. cm.l.k.Pause() p, err := createPlatform(cm.l.conf, deviceFile) if err != nil { return fmt.Errorf("creating platform: %v", err) } k := &kernel.Kernel{ Platform: p, } mf, err := createMemoryFile() if err != nil { return fmt.Errorf("creating memory file: %v", err) } k.SetMemoryFile(mf) networkStack := cm.l.k.NetworkStack() cm.l.k = k // Set up the restore environment. mntr := newContainerMounter(cm.l.spec, cm.l.goferFDs, cm.l.k, cm.l.mountHints) renv, err := mntr.createRestoreEnvironment(cm.l.conf) if err != nil { return fmt.Errorf("creating RestoreEnvironment: %v", err) } fs.SetRestoreEnvironment(*renv) // Prepare to load from the state file. if eps, ok := networkStack.(*epsocket.Stack); ok { stack.StackFromEnv = eps.Stack // FIXME(b/36201077) } info, err := specFile.Stat() if err != nil { return err } if info.Size() == 0 { return fmt.Errorf("file cannot be empty") } if cm.l.conf.ProfileEnable { // initializePProf opens /proc/self/maps, so has to be // called before installing seccomp filters. initializePProf() } // Seccomp filters have to be applied before parsing the state file. if err := cm.l.installSeccompFilters(); err != nil { return err } // Load the state. loadOpts := state.LoadOpts{Source: specFile} if err := loadOpts.Load(k, networkStack, time.NewCalibratedClocks()); err != nil { return err } // Since we have a new kernel we also must make a new watchdog. dog := watchdog.New(k, watchdog.DefaultTimeout, cm.l.conf.WatchdogAction) // Change the loader fields to reflect the changes made when restoring. cm.l.k = k cm.l.watchdog = dog cm.l.rootProcArgs = kernel.CreateProcessArgs{} cm.l.restore = true // Reinitialize the sandbox ID and processes map. Note that it doesn't // restore the state of multiple containers, nor exec processes. cm.l.sandboxID = o.SandboxID cm.l.mu.Lock() eid := execID{cid: o.SandboxID} cm.l.processes = map[execID]*execProcess{ eid: { tg: cm.l.k.GlobalInit(), }, } cm.l.mu.Unlock() // Tell the root container to start and wait for the result. cm.startChan <- struct{}{} if err := <-cm.startResultChan; err != nil { return fmt.Errorf("starting sandbox: %v", err) } return nil } // Resume unpauses a container. func (cm *containerManager) Resume(_, _ *struct{}) error { log.Debugf("containerManager.Resume") cm.l.k.Unpause() return nil } // Wait waits for the init process in the given container. func (cm *containerManager) Wait(cid *string, waitStatus *uint32) error { log.Debugf("containerManager.Wait") err := cm.l.waitContainer(*cid, waitStatus) log.Debugf("containerManager.Wait returned, waitStatus: %v: %v", waitStatus, err) return err } // WaitPIDArgs are arguments to the WaitPID method. type WaitPIDArgs struct { // PID is the PID in the container's PID namespace. PID int32 // CID is the container ID. CID string } // WaitPID waits for the process with PID 'pid' in the sandbox. func (cm *containerManager) WaitPID(args *WaitPIDArgs, waitStatus *uint32) error { log.Debugf("containerManager.Wait") return cm.l.waitPID(kernel.ThreadID(args.PID), args.CID, waitStatus) } // SignalDeliveryMode enumerates different signal delivery modes. type SignalDeliveryMode int const ( // DeliverToProcess delivers the signal to the container process with // the specified PID. If PID is 0, then the container init process is // signaled. DeliverToProcess SignalDeliveryMode = iota // DeliverToAllProcesses delivers the signal to all processes in the // container. PID must be 0. DeliverToAllProcesses // DeliverToForegroundProcessGroup delivers the signal to the // foreground process group in the same TTY session as the specified // process. If PID is 0, then the signal is delivered to the foreground // process group for the TTY for the init process. DeliverToForegroundProcessGroup ) func (s SignalDeliveryMode) String() string { switch s { case DeliverToProcess: return "Process" case DeliverToAllProcesses: return "All" case DeliverToForegroundProcessGroup: return "Foreground Process Group" } return fmt.Sprintf("unknown signal delivery mode: %d", s) } // SignalArgs are arguments to the Signal method. type SignalArgs struct { // CID is the container ID. CID string // Signo is the signal to send to the process. Signo int32 // PID is the process ID in the given container that will be signaled. // If 0, the root container will be signalled. PID int32 // Mode is the signal delivery mode. Mode SignalDeliveryMode } // Signal sends a signal to one or more processes in a container. If args.PID // is 0, then the container init process is used. Depending on the // args.SignalDeliveryMode option, the signal may be sent directly to the // indicated process, to all processes in the container, or to the foreground // process group. func (cm *containerManager) Signal(args *SignalArgs, _ *struct{}) error { log.Debugf("containerManager.Signal %+v", args) return cm.l.signal(args.CID, args.PID, args.Signo, args.Mode) }