forked from MetaCubeX/gvisor
/
lifecycle.go
520 lines (435 loc) · 15.6 KB
/
lifecycle.go
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// Copyright 2021 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 control
import (
"encoding/json"
"fmt"
"time"
"google.golang.org/protobuf/types/known/timestamppb"
"github.com/MerlinKodo/gvisor/pkg/abi/linux"
"github.com/MerlinKodo/gvisor/pkg/eventchannel"
"github.com/MerlinKodo/gvisor/pkg/fd"
"github.com/MerlinKodo/gvisor/pkg/log"
pb "github.com/MerlinKodo/gvisor/pkg/sentry/control/control_go_proto"
"github.com/MerlinKodo/gvisor/pkg/sentry/fdimport"
"github.com/MerlinKodo/gvisor/pkg/sentry/fsimpl/user"
"github.com/MerlinKodo/gvisor/pkg/sentry/kernel"
"github.com/MerlinKodo/gvisor/pkg/sentry/kernel/auth"
"github.com/MerlinKodo/gvisor/pkg/sentry/limits"
"github.com/MerlinKodo/gvisor/pkg/sentry/vfs"
"github.com/MerlinKodo/gvisor/pkg/sync"
"github.com/MerlinKodo/gvisor/pkg/urpc"
)
// Lifecycle provides functions related to starting and stopping tasks.
type Lifecycle struct {
// Kernel is the kernel where the tasks belong to.
Kernel *kernel.Kernel
// ShutdownCh is the channel used to signal the sentry to shutdown
// the sentry/sandbox.
ShutdownCh chan struct{}
// mu protects the fields below.
mu sync.RWMutex
// MountNamespacesMap is a map of container id/names and the mount
// namespaces.
MountNamespacesMap map[string]*vfs.MountNamespace
// containerMap is a map of the container id and the container.
containerMap map[string]*Container
}
// containerState is the state of the container.
type containerState int
const (
// stateCreated is the state when the container was created. It is the
// initial state.
stateCreated containerState = iota
// stateRunning is the state when the container/application is running.
stateRunning
// stateStopped is the state when the container has exited.
stateStopped
)
// Container contains the set of parameters to represent a container.
type Container struct {
// containerID.
containerID string
// tg is the init(PID 1) threadgroup of the container.
tg *kernel.ThreadGroup
// state is the current state of the container.
state containerState
}
// StartContainerArgs is the set of arguments to start a container.
type StartContainerArgs struct {
// Filename is the filename to load.
//
// If this is provided as "", then the file will be guessed via Argv[0].
Filename string `json:"filename"`
// Argv is a list of arguments.
Argv []string `json:"argv"`
// Envv is a list of environment variables.
Envv []string `json:"envv"`
// Secret_envv is a list of secret environment variables.
//
// NOTE: This field must never be logged!
SecretEnvv []string `json:"secret_envv"`
// WorkingDirectory defines the working directory for the new process.
WorkingDirectory string `json:"wd"`
// KUID is the UID to run with in the root user namespace. Defaults to
// root if not set explicitly.
KUID auth.KUID `json:"KUID"`
// KGID is the GID to run with in the root user namespace. Defaults to
// the root group if not set explicitly.
KGID auth.KGID `json:"KGID"`
// ContainerID is the container for the process being executed.
ContainerID string `json:"container_id"`
// InitialCgroups is the set of cgroup controllers container needs to be initialised to.
InitialCgroups map[kernel.CgroupControllerType]string `json:"initial_cgroups"`
// Limits is the limit set for the process being executed.
Limits map[string]limits.Limit `json:"limits"`
// If HOME environment variable is not provided, and this flag is set,
// then the HOME environment variable will be set inside the container
// based on the user's home directory in /etc/passwd.
ResolveHome bool `json:"resolve_home"`
// If set, attempt to resolve the binary_path via the following procedure:
// 1) If binary_path is absolute, it is used directly.
// 2) If binary_path contains a slash, then it is resolved relative to the
// working_directory (or the root it working_directory is not set).
// 3) Otherwise, search the PATH environment variable for the first directory
// that contains an executable file with name in binary_path.
ResolveBinaryPath bool `json:"resolve_binary_path"`
// DonatedFDs is the list of sentry-intrenal file descriptors that will
// donated. They correspond to the donated files in FilePayload.
DonatedFDs []int `json:"donated_fds"`
// FilePayload determines the files to give to the new process.
urpc.FilePayload
}
// String formats the StartContainerArgs without the SecretEnvv field.
func (sca StartContainerArgs) String() string {
sca.SecretEnvv = make([]string, len(sca.SecretEnvv))
for i := range sca.SecretEnvv {
sca.SecretEnvv[i] = "(hidden)"
}
b, err := json.Marshal(sca)
if err != nil {
return fmt.Sprintf("error marshaling: %s", err)
}
return string(b)
}
func (l *Lifecycle) updateContainerState(containerID string, newState containerState) error {
l.mu.Lock()
defer l.mu.Unlock()
c, ok := l.containerMap[containerID]
if !ok {
return fmt.Errorf("container %v not started", containerID)
}
switch newState {
case stateCreated:
// Impossible.
panic(fmt.Sprintf("invalid state transition: %v => %v", c.state, newState))
case stateRunning:
if c.state != stateCreated {
// Impossible.
panic(fmt.Sprintf("invalid state transition: %v => %v", c.state, newState))
}
case stateStopped:
// Valid state transition.
default:
// Invalid new state.
panic(fmt.Sprintf("invalid new state: %v", newState))
}
c.state = newState
return nil
}
// StartContainer will start a new container in the sandbox.
func (l *Lifecycle) StartContainer(args *StartContainerArgs, _ *uint32) error {
timeRequested := time.Now()
timeRequestReceived := ×tamppb.Timestamp{
Seconds: timeRequested.Unix(),
Nanos: int32(timeRequested.Nanosecond()),
}
log.Infof("StartContainer: %v", args)
if len(args.Files) != len(args.DonatedFDs) {
return fmt.Errorf("FilePayload.Files and DonatedFDs must have same number of elements (%d != %d)", len(args.Files), len(args.DonatedFDs))
}
creds := auth.NewUserCredentials(
args.KUID,
args.KGID,
nil, /* extraKGIDs */
nil, /* capabilities */
l.Kernel.RootUserNamespace())
ls, err := limits.NewLinuxDistroLimitSet()
if err != nil {
return fmt.Errorf("error creating default limit set: %w", err)
}
for name, limit := range args.Limits {
lt, ok := limits.FromLinuxResourceName[name]
if !ok {
return fmt.Errorf("unknown limit %q", name)
}
ls.SetUnchecked(lt, limit)
}
// Create a new pid namespace for the container. Each container must run
// in its own pid namespace.
pidNs := l.Kernel.RootPIDNamespace().NewChild(l.Kernel.RootUserNamespace())
initArgs := kernel.CreateProcessArgs{
Filename: args.Filename,
Argv: args.Argv,
// Order Envv before SecretEnvv.
Envv: append(args.Envv, args.SecretEnvv...),
WorkingDirectory: args.WorkingDirectory,
Credentials: creds,
Umask: 0022,
Limits: ls,
MaxSymlinkTraversals: linux.MaxSymlinkTraversals,
UTSNamespace: l.Kernel.RootUTSNamespace(),
IPCNamespace: l.Kernel.RootIPCNamespace(),
AbstractSocketNamespace: l.Kernel.RootAbstractSocketNamespace(),
ContainerID: args.ContainerID,
PIDNamespace: pidNs,
}
ctx := initArgs.NewContext(l.Kernel)
// Import file descriptors.
fdTable := l.Kernel.NewFDTable()
defer fdTable.DecRef(ctx)
hostFDs, err := fd.NewFromFiles(args.Files)
if err != nil {
return fmt.Errorf("error donating host files: %w", err)
}
defer func() {
for _, hfd := range hostFDs {
_ = hfd.Close()
}
}()
fdMap := make(map[int]*fd.FD, len(args.DonatedFDs))
for i, appFD := range args.DonatedFDs {
fdMap[appFD] = hostFDs[i]
}
if _, err := fdimport.Import(ctx, fdTable, false, args.KUID, args.KGID, fdMap); err != nil {
return fmt.Errorf("error importing host files: %w", err)
}
initArgs.FDTable = fdTable
l.mu.RLock()
mntns, ok := l.MountNamespacesMap[initArgs.ContainerID]
if !ok {
l.mu.RUnlock()
return fmt.Errorf("mount namespace is nil for %s", initArgs.ContainerID)
}
initArgs.MountNamespace = mntns
l.mu.RUnlock()
initArgs.MountNamespace.IncRef()
if args.ResolveBinaryPath {
resolved, err := user.ResolveExecutablePath(ctx, &initArgs)
if err != nil {
return fmt.Errorf("failed to resolve binary path: %w", err)
}
initArgs.Filename = resolved
}
if args.ResolveHome {
envVars, err := user.MaybeAddExecUserHome(ctx, initArgs.MountNamespace, creds.RealKUID, initArgs.Envv)
if err != nil {
return fmt.Errorf("failed to get user home dir: %w", err)
}
initArgs.Envv = envVars
}
fds, err := fd.NewFromFiles(args.Files)
if err != nil {
return fmt.Errorf("duplicating payload files: %w", err)
}
defer func() {
for _, fd := range fds {
_ = fd.Close()
}
}()
initialCgroups := make(map[kernel.Cgroup]struct{}, len(args.InitialCgroups))
cgroupRegistry := l.Kernel.CgroupRegistry()
// path is relative to the container's cgroup controller of specified type.
for initialCgroupController, path := range args.InitialCgroups {
cg, err := cgroupRegistry.FindCgroup(ctx, initialCgroupController, path)
if err != nil {
return fmt.Errorf("FindCgroup can't locate cgroup controller: %v err: %v", initialCgroupController, err)
}
initialCgroups[cg] = struct{}{}
}
initArgs.InitialCgroups = initialCgroups
tg, _, err := l.Kernel.CreateProcess(initArgs)
if err != nil {
return err
}
c := &Container{
containerID: initArgs.ContainerID,
tg: tg,
state: stateCreated,
}
l.mu.Lock()
if l.containerMap == nil {
l.containerMap = make(map[string]*Container)
}
if _, ok := l.containerMap[initArgs.ContainerID]; ok {
l.mu.Unlock()
return fmt.Errorf("container id: %v already exists", initArgs.ContainerID)
}
l.containerMap[initArgs.ContainerID] = c
l.mu.Unlock()
// Start the newly created process.
l.Kernel.StartProcess(tg)
log.Infof("Started the new container %v ", initArgs.ContainerID)
if err := l.updateContainerState(initArgs.ContainerID, stateRunning); err != nil {
// Sanity check: shouldn't fail to update the state at this point.
panic(fmt.Sprintf("Failed to set running state: %v", err))
}
timeRequestCompleted := time.Now()
eventchannel.LogEmit(&pb.ContainerStartedEvent{
Started: true,
ContainerId: initArgs.ContainerID,
RequestReceived: timeRequestReceived,
RequestCompleted: ×tamppb.Timestamp{
Seconds: timeRequestCompleted.Unix(),
Nanos: int32(timeRequestCompleted.Nanosecond()),
},
})
// TODO(b/251490950): reap thread needs to synchronize with Save, so the
// container state update doesn't race with state serialization.
go l.reap(initArgs.ContainerID, tg) // S/R-SAFE: see above.
return nil
}
func (l *Lifecycle) reap(containerID string, tg *kernel.ThreadGroup) {
tg.WaitExited()
if err := l.updateContainerState(containerID, stateStopped); err != nil {
panic(err)
}
eventchannel.LogEmit(&pb.ContainerExitEvent{
ContainerId: containerID,
ExitStatus: uint32(tg.ExitStatus()),
})
}
// Pause pauses all tasks, blocking until they are stopped.
func (l *Lifecycle) Pause(_, _ *struct{}) error {
l.Kernel.Pause()
return nil
}
// Resume resumes all tasks.
func (l *Lifecycle) Resume(_, _ *struct{}) error {
l.Kernel.Unpause()
return nil
}
// Shutdown sends signal to destroy the sentry/sandbox.
func (l *Lifecycle) Shutdown(_, _ *struct{}) error {
close(l.ShutdownCh)
return nil
}
func (l *Lifecycle) getInitContainerProcess(containerID string) (*kernel.ThreadGroup, error) {
l.mu.Lock()
defer l.mu.Unlock()
c, ok := l.containerMap[containerID]
if !ok {
return nil, fmt.Errorf("container %v not started", containerID)
}
return c.tg, nil
}
// ContainerArgs is the set of arguments for container related APIs after
// starting the container.
type ContainerArgs struct {
ContainerID string `json:"container_id"`
}
// GetExitStatus returns the container exit status if it has stopped.
func (l *Lifecycle) GetExitStatus(args *ContainerArgs, status *uint32) error {
l.mu.Lock()
defer l.mu.Unlock()
c, ok := l.containerMap[args.ContainerID]
if !ok {
return fmt.Errorf("container %q doesn't exist, or has not been started", args.ContainerID)
}
if c.state != stateStopped {
return fmt.Errorf("container %q hasn't exited yet", args.ContainerID)
}
*status = uint32(c.tg.ExitStatus())
eventchannel.LogEmit(&pb.ContainerExitEvent{
ContainerId: args.ContainerID,
ExitStatus: *status,
})
return nil
}
// Reap notifies the sandbox that the caller is interested in the exit status via
// an exit event. The caller is responsible for handling any corresponding exit
// events, especially if they're interested in waiting for the exit.
func (l *Lifecycle) Reap(args *ContainerArgs, _ *struct{}) error {
// Check if there are any real emitters registered. If there are no
// emitters, the caller will never be notified, so fail immediately.
if !eventchannel.HaveEmitters() {
return fmt.Errorf("no event emitters configured")
}
l.mu.Lock()
c, ok := l.containerMap[args.ContainerID]
if !ok {
l.mu.Unlock()
return fmt.Errorf("no container with id %q", args.ContainerID)
}
// Once a container enters the stop state, the state never changes. It's
// safe to cache a stopped state outside a l.mu critical section.
isStopped := c.state == stateStopped
l.mu.Unlock()
if isStopped {
// Already stopped, emit stop to ensure any callbacks registered after
// the actual stop is called. This may be a duplicate event, but is
// necessary in case the reap goroutine transitions the container to the
// stop state before the caller starts observing the event channel.
eventchannel.LogEmit(&pb.ContainerExitEvent{
ContainerId: args.ContainerID,
ExitStatus: uint32(c.tg.ExitStatus()),
})
}
// Caller now responsible for blocking on the exit event.
return nil
}
// IsContainerRunning returns true if the container is running.
func (l *Lifecycle) IsContainerRunning(args *ContainerArgs, isRunning *bool) error {
l.mu.Lock()
defer l.mu.Unlock()
c, ok := l.containerMap[args.ContainerID]
// We may be racing with the reaper goroutine updating c.state, so also
// check the number non-exited tasks.
if !ok || c.state != stateRunning || c.tg.Count() == 0 {
return nil
}
*isRunning = true
return nil
}
// SignalContainerArgs is the set of arguments for signalling a container.
type SignalContainerArgs struct {
ContainerID string `json:"container_id"`
Signo int32 `json:"signo"`
SignalAll bool `json:"signalAll"`
}
// SignalContainer signals the container in multi-container mode. It returns error if the
// container hasn't started or has exited.
func (l *Lifecycle) SignalContainer(args *SignalContainerArgs, _ *struct{}) error {
tg, err := l.getInitContainerProcess(args.ContainerID)
if err != nil {
return err
}
l.mu.Lock()
c, ok := l.containerMap[args.ContainerID]
if !ok || c.state != stateRunning {
l.mu.Unlock()
return fmt.Errorf("%v container not running", args.ContainerID)
}
l.mu.Unlock()
// Signalling a single process is supported only for the init process.
if !args.SignalAll {
if tg == nil {
return fmt.Errorf("no process exists in %v", tg)
}
return l.Kernel.SendExternalSignalThreadGroup(tg, &linux.SignalInfo{Signo: args.Signo})
}
l.Kernel.Pause()
defer l.Kernel.Unpause()
return l.Kernel.SendContainerSignal(args.ContainerID, &linux.SignalInfo{Signo: args.Signo})
}