Refactor the Sandbox package into Sandbox + Container.

This is a necessary prerequisite for supporting multiple containers in a single
sandbox.

All the commands (in cmd package) now call operations on Containers (container
package). When a Container first starts, it will create a Sandbox with the same
ID.

The Sandbox class is now simpler, as it only knows how to create boot/gofer
processes, and how to forward commands into the running boot process.

There are TODOs sprinkled around for additional support for multiple
containers. Most notably, we need to detect when a container is intended to run
in an existing sandbox (by reading the metadata), and then have some way to
signal to the sandbox to start a new container. Other urpc calls into the
sandbox need to pass the container ID, so the sandbox can run the operation on
the given container. These are only half-plummed through right now.

PiperOrigin-RevId: 196688269
Change-Id: I1ecf4abbb9dd8987a53ae509df19341aaf42b5b0

1 files changed, 669 insertions, 0 deletions

diff --git a/runsc/container/container_test.go b/runsc/container/container_test.go
new file mode 100644
index 000000000..67efd2f9e
--- /dev/null
+++ b/runsc/container/container_test.go
@@ -0,0 +1,669 @@
+// Copyright 2018 Google Inc.
+//
+// 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 container_test
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"os/signal"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"syscall"
+	"testing"
+	"time"
+
+	"context"
+	"flag"
+	"github.com/google/subcommands"
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+	"golang.org/x/sys/unix"
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+	"gvisor.googlesource.com/gvisor/pkg/log"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/control"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/kernel/auth"
+	"gvisor.googlesource.com/gvisor/pkg/unet"
+	"gvisor.googlesource.com/gvisor/runsc/boot"
+	"gvisor.googlesource.com/gvisor/runsc/cmd"
+	"gvisor.googlesource.com/gvisor/runsc/container"
+)
+
+func init() {
+	log.SetLevel(log.Debug)
+}
+
+// writeSpec writes the spec to disk in the given directory.
+func writeSpec(dir string, spec *specs.Spec) error {
+	b, err := json.Marshal(spec)
+	if err != nil {
+		return err
+	}
+	return ioutil.WriteFile(filepath.Join(dir, "config.json"), b, 0755)
+}
+
+// newSpecWithArgs creates a simple spec with the given args suitable for use
+// in tests.
+func newSpecWithArgs(args ...string) *specs.Spec {
+	spec := &specs.Spec{
+		// The host filesystem root is the container root.
+		Root: &specs.Root{
+			Path:     "/",
+			Readonly: true,
+		},
+		Process: &specs.Process{
+			Args: args,
+			Env: []string{
+				"PATH=" + os.Getenv("PATH"),
+			},
+		},
+	}
+	return spec
+}
+
+// shutdownSignal will be sent to the sandbox in order to shut down cleanly.
+const shutdownSignal = syscall.SIGUSR2
+
+// setupContainer creates a bundle and root dir for the container, generates a
+// test config, and writes the spec to config.json in the bundle dir.
+func setupContainer(spec *specs.Spec) (rootDir, bundleDir string, conf *boot.Config, err error) {
+	rootDir, err = ioutil.TempDir("", "containers")
+	if err != nil {
+		return "", "", nil, fmt.Errorf("error creating root dir: %v", err)
+	}
+
+	bundleDir, err = ioutil.TempDir("", "bundle")
+	if err != nil {
+		return "", "", nil, fmt.Errorf("error creating bundle dir: %v", err)
+	}
+
+	if err = writeSpec(bundleDir, spec); err != nil {
+		return "", "", nil, fmt.Errorf("error writing spec: %v", err)
+	}
+
+	conf = &boot.Config{
+		RootDir: rootDir,
+		Network: boot.NetworkNone,
+		// Don't add flags when calling subprocesses, since the test
+		// runner does not know about all the flags. We control the
+		// Config in the subprocess anyways, so it does not matter.
+		TestModeNoFlags: true,
+	}
+
+	return rootDir, bundleDir, conf, nil
+}
+
+// uniqueContainerID generates a unique container id for each test.
+//
+// The container id is used to create an abstract unix domain socket, which must
+// be unique.  While the container forbids creating two containers with the same
+// name, sometimes between test runs the socket does not get cleaned up quickly
+// enough, causing container creation to fail.
+func uniqueContainerID() string {
+	return fmt.Sprintf("test-container-%d", time.Now().UnixNano())
+}
+
+// waitForProcessList waits for the given process list to show up in the container.
+func waitForProcessList(s *container.Container, expected []*control.Process) error {
+	var got []*control.Process
+	for start := time.Now(); time.Now().Sub(start) < 10*time.Second; {
+		var err error
+		got, err := s.Processes()
+		if err != nil {
+			return fmt.Errorf("error getting process data from container: %v", err)
+		}
+		if procListsEqual(got, expected) {
+			return nil
+		}
+		// Process might not have started, try again...
+		time.Sleep(10 * time.Millisecond)
+	}
+	return fmt.Errorf("container got process list: %s, want: %s", procListToString(got), procListToString(expected))
+}
+
+// TestLifecycle tests the basic Create/Start/Signal/Destroy container lifecycle.
+// It verifies after each step that the container can be loaded from disk, and
+// has the correct status.
+func TestLifecycle(t *testing.T) {
+	// The container will just sleep for a long time.  We will kill it before
+	// it finishes sleeping.
+	spec := newSpecWithArgs("sleep", "100")
+
+	rootDir, bundleDir, conf, err := setupContainer(spec)
+	if err != nil {
+		t.Fatalf("error setting up container: %v", err)
+	}
+	defer os.RemoveAll(rootDir)
+	defer os.RemoveAll(bundleDir)
+
+	// expectedPL lists the expected process state of the container.
+	expectedPL := []*control.Process{
+		{
+			UID:  0,
+			PID:  1,
+			PPID: 0,
+			C:    0,
+			Cmd:  "sleep",
+		},
+	}
+	// Create the container.
+	id := uniqueContainerID()
+	if _, err := container.Create(id, spec, conf, bundleDir, "", ""); err != nil {
+		t.Fatalf("error creating container: %v", err)
+	}
+	// Load the container from disk and check the status.
+	s, err := container.Load(rootDir, id)
+	if err != nil {
+		t.Fatalf("error loading container: %v", err)
+	}
+	if got, want := s.Status, container.Created; got != want {
+		t.Errorf("container status got %v, want %v", got, want)
+	}
+
+	// List should return the container id.
+	ids, err := container.List(rootDir)
+	if err != nil {
+		t.Fatalf("error listing containers: %v", err)
+	}
+	if got, want := ids, []string{id}; !reflect.DeepEqual(got, want) {
+		t.Errorf("container list got %v, want %v", got, want)
+	}
+
+	// Start the container.
+	if err := s.Start(conf); err != nil {
+		t.Fatalf("error starting container: %v", err)
+	}
+	// Load the container from disk and check the status.
+	s, err = container.Load(rootDir, id)
+	if err != nil {
+		t.Fatalf("error loading container: %v", err)
+	}
+	if got, want := s.Status, container.Running; got != want {
+		t.Errorf("container status got %v, want %v", got, want)
+	}
+
+	// Verify that "sleep 100" is running.
+	if err := waitForProcessList(s, expectedPL); err != nil {
+		t.Error(err)
+	}
+
+	// Send the container a signal, which we catch and use to cleanly
+	// shutdown.
+	if err := s.Signal(shutdownSignal); err != nil {
+		t.Fatalf("error sending signal %v to container: %v", shutdownSignal, err)
+	}
+	// Wait for it to die.
+	if _, err := s.Wait(); err != nil {
+		t.Fatalf("error waiting on container: %v", err)
+	}
+	// Load the container from disk and check the status.
+	s, err = container.Load(rootDir, id)
+	if err != nil {
+		t.Fatalf("error loading container: %v", err)
+	}
+	if got, want := s.Status, container.Stopped; got != want {
+		t.Errorf("container status got %v, want %v", got, want)
+	}
+
+	// Destroy the container.
+	if err := s.Destroy(); err != nil {
+		t.Fatalf("error destroying container: %v", err)
+	}
+
+	// List should not return the container id.
+	ids, err = container.List(rootDir)
+	if err != nil {
+		t.Fatalf("error listing containers: %v", err)
+	}
+	if len(ids) != 0 {
+		t.Errorf("expected container list to be empty, but got %v", ids)
+	}
+
+	// Loading the container by id should fail.
+	if _, err = container.Load(rootDir, id); err == nil {
+		t.Errorf("expected loading destroyed container to fail, but it did not")
+	}
+}
+
+// Test the we can execute the application with different path formats.
+func TestExePath(t *testing.T) {
+	for _, test := range []struct {
+		path    string
+		success bool
+	}{
+		{path: "true", success: true},
+		{path: "bin/true", success: true},
+		{path: "/bin/true", success: true},
+		{path: "thisfiledoesntexit", success: false},
+		{path: "bin/thisfiledoesntexit", success: false},
+		{path: "/bin/thisfiledoesntexit", success: false},
+	} {
+		spec := newSpecWithArgs(test.path)
+		rootDir, bundleDir, conf, err := setupContainer(spec)
+		if err != nil {
+			t.Fatalf("exec: %s, error setting up container: %v", test.path, err)
+		}
+
+		ws, err := container.Run(uniqueContainerID(), spec, conf, bundleDir, "", "")
+
+		os.RemoveAll(rootDir)
+		os.RemoveAll(bundleDir)
+
+		if test.success {
+			if err != nil {
+				t.Errorf("exec: %s, error running container: %v", test.path, err)
+			}
+			if ws.ExitStatus() != 0 {
+				t.Errorf("exec: %s, got exit status %v want %v", test.path, ws.ExitStatus(), 0)
+			}
+		} else {
+			if err == nil {
+				t.Errorf("exec: %s, got: no error, want: error", test.path)
+			}
+		}
+	}
+}
+
+// Test the we can retrieve the application exit status from the container.
+func TestAppExitStatus(t *testing.T) {
+	// First container will succeed.
+	succSpec := newSpecWithArgs("true")
+
+	rootDir, bundleDir, conf, err := setupContainer(succSpec)
+	if err != nil {
+		t.Fatalf("error setting up container: %v", err)
+	}
+	defer os.RemoveAll(rootDir)
+	defer os.RemoveAll(bundleDir)
+
+	ws, err := container.Run(uniqueContainerID(), succSpec, conf, bundleDir, "", "")
+	if err != nil {
+		t.Fatalf("error running container: %v", err)
+	}
+	if ws.ExitStatus() != 0 {
+		t.Errorf("got exit status %v want %v", ws.ExitStatus(), 0)
+	}
+
+	// Second container exits with non-zero status.
+	wantStatus := 123
+	errSpec := newSpecWithArgs("bash", "-c", fmt.Sprintf("exit %d", wantStatus))
+
+	rootDir2, bundleDir2, conf, err := setupContainer(errSpec)
+	if err != nil {
+		t.Fatalf("error setting up container: %v", err)
+	}
+	defer os.RemoveAll(rootDir2)
+	defer os.RemoveAll(bundleDir2)
+
+	ws, err = container.Run(uniqueContainerID(), succSpec, conf, bundleDir2, "", "")
+	if err != nil {
+		t.Fatalf("error running container: %v", err)
+	}
+	if ws.ExitStatus() != wantStatus {
+		t.Errorf("got exit status %v want %v", ws.ExitStatus(), wantStatus)
+	}
+}
+
+// TestExec verifies that a container can exec a new program.
+func TestExec(t *testing.T) {
+	const uid = 343
+	spec := newSpecWithArgs("sleep", "100")
+
+	rootDir, bundleDir, conf, err := setupContainer(spec)
+	if err != nil {
+		t.Fatalf("error setting up container: %v", err)
+	}
+	defer os.RemoveAll(rootDir)
+	defer os.RemoveAll(bundleDir)
+
+	// Create and start the container.
+	s, err := container.Create(uniqueContainerID(), spec, conf, bundleDir, "", "")
+	if err != nil {
+		t.Fatalf("error creating container: %v", err)
+	}
+	defer s.Destroy()
+	if err := s.Start(conf); err != nil {
+		t.Fatalf("error starting container: %v", err)
+	}
+
+	// expectedPL lists the expected process state of the container.
+	expectedPL := []*control.Process{
+		{
+			UID:  0,
+			PID:  1,
+			PPID: 0,
+			C:    0,
+			Cmd:  "sleep",
+		},
+		{
+			UID:  uid,
+			PID:  2,
+			PPID: 0,
+			C:    0,
+			Cmd:  "sleep",
+		},
+	}
+
+	// Verify that "sleep 100" is running.
+	if err := waitForProcessList(s, expectedPL[:1]); err != nil {
+		t.Error(err)
+	}
+
+	execArgs := control.ExecArgs{
+		Filename:         "/bin/sleep",
+		Argv:             []string{"sleep", "5"},
+		Envv:             []string{"PATH=" + os.Getenv("PATH")},
+		WorkingDirectory: "/",
+		KUID:             uid,
+	}
+
+	// Verify that "sleep 100" and "sleep 5" are running after exec.
+	// First, start running exec (whick blocks).
+	status := make(chan error, 1)
+	go func() {
+		exitStatus, err := s.Execute(&execArgs)
+		if err != nil {
+			status <- err
+		} else if exitStatus != 0 {
+			status <- fmt.Errorf("failed with exit status: %v", exitStatus)
+		} else {
+			status <- nil
+		}
+	}()
+
+	if err := waitForProcessList(s, expectedPL); err != nil {
+		t.Fatal(err)
+	}
+
+	// Ensure that exec finished without error.
+	select {
+	case <-time.After(10 * time.Second):
+		t.Fatalf("container timed out waiting for exec to finish.")
+	case st := <-status:
+		if st != nil {
+			t.Errorf("container failed to exec %v: %v", execArgs, err)
+		}
+	}
+}
+
+// TestCapabilities verifies that:
+// - Running exec as non-root UID and GID will result in an error (because the
+//   executable file can't be read).
+// - Running exec as non-root with CAP_DAC_OVERRIDE succeeds because it skips
+//   this check.
+func TestCapabilities(t *testing.T) {
+	const uid = 343
+	const gid = 2401
+	spec := newSpecWithArgs("sleep", "100")
+
+	// We generate files in the host temporary directory.
+	spec.Mounts = append(spec.Mounts, specs.Mount{
+		Destination: os.TempDir(),
+		Source:      os.TempDir(),
+		Type:        "bind",
+	})
+
+	rootDir, bundleDir, conf, err := setupContainer(spec)
+	if err != nil {
+		t.Fatalf("error setting up container: %v", err)
+	}
+	defer os.RemoveAll(rootDir)
+	defer os.RemoveAll(bundleDir)
+
+	// Create and start the container.
+	s, err := container.Create(uniqueContainerID(), spec, conf, bundleDir, "", "")
+	if err != nil {
+		t.Fatalf("error creating container: %v", err)
+	}
+	defer s.Destroy()
+	if err := s.Start(conf); err != nil {
+		t.Fatalf("error starting container: %v", err)
+	}
+
+	// expectedPL lists the expected process state of the container.
+	expectedPL := []*control.Process{
+		{
+			UID:  0,
+			PID:  1,
+			PPID: 0,
+			C:    0,
+			Cmd:  "sleep",
+		},
+		{
+			UID:  uid,
+			PID:  2,
+			PPID: 0,
+			C:    0,
+			Cmd:  "exe",
+		},
+	}
+	if err := waitForProcessList(s, expectedPL[:1]); err != nil {
+		t.Fatalf("Failed to wait for sleep to start, err: %v", err)
+	}
+
+	// Create an executable that can't be run with the specified UID:GID.
+	// This shouldn't be callable within the container until we add the
+	// CAP_DAC_OVERRIDE capability to skip the access check.
+	exePath := filepath.Join(rootDir, "exe")
+	if err := ioutil.WriteFile(exePath, []byte("#!/bin/sh\necho hello"), 0770); err != nil {
+		t.Fatalf("couldn't create executable: %v", err)
+	}
+	defer os.Remove(exePath)
+
+	// Need to traverse the intermediate directory.
+	os.Chmod(rootDir, 0755)
+
+	execArgs := control.ExecArgs{
+		Filename:         exePath,
+		Argv:             []string{exePath},
+		Envv:             []string{"PATH=" + os.Getenv("PATH")},
+		WorkingDirectory: "/",
+		KUID:             uid,
+		KGID:             gid,
+		Capabilities:     &auth.TaskCapabilities{},
+	}
+
+	// "exe" should fail because we don't have the necessary permissions.
+	if _, err := s.Execute(&execArgs); err == nil {
+		t.Fatalf("container executed without error, but an error was expected")
+	}
+
+	// Now we run with the capability enabled and should succeed.
+	execArgs.Capabilities = &auth.TaskCapabilities{
+		EffectiveCaps: auth.CapabilitySetOf(linux.CAP_DAC_OVERRIDE),
+	}
+	// "exe" should not fail this time.
+	if _, err := s.Execute(&execArgs); err != nil {
+		t.Fatalf("container failed to exec %v: %v", execArgs, err)
+	}
+}
+
+// Test that an tty FD is sent over the console socket if one is provided.
+func TestConsoleSocket(t *testing.T) {
+	spec := newSpecWithArgs("true")
+	rootDir, bundleDir, conf, err := setupContainer(spec)
+	if err != nil {
+		t.Fatalf("error setting up container: %v", err)
+	}
+	defer os.RemoveAll(rootDir)
+	defer os.RemoveAll(bundleDir)
+
+	// Create a named socket and start listening.  We use a relative path
+	// to avoid overflowing the unix path length limit (108 chars).
+	socketPath := filepath.Join(bundleDir, "socket")
+	cwd, err := os.Getwd()
+	if err != nil {
+		t.Fatalf("error getting cwd: %v", err)
+	}
+	socketRelPath, err := filepath.Rel(cwd, socketPath)
+	if err != nil {
+		t.Fatalf("error getting relative path for %q from cwd %q: %v", socketPath, cwd, err)
+	}
+	if len(socketRelPath) > len(socketPath) {
+		socketRelPath = socketPath
+	}
+	srv, err := unet.BindAndListen(socketRelPath, false)
+	if err != nil {
+		t.Fatalf("error binding and listening to socket %q: %v", socketPath, err)
+	}
+	defer os.Remove(socketPath)
+
+	// Create the container and pass the socket name.
+	id := uniqueContainerID()
+	s, err := container.Create(id, spec, conf, bundleDir, socketRelPath, "")
+	if err != nil {
+		t.Fatalf("error creating container: %v", err)
+	}
+
+	// Open the othe end of the socket.
+	sock, err := srv.Accept()
+	if err != nil {
+		t.Fatalf("error accepting socket connection: %v", err)
+	}
+
+	// Allow 3 fds to be received.  We only expect 1.
+	r := sock.Reader(true /* blocking */)
+	r.EnableFDs(1)
+
+	// The socket is closed right after sending the FD, so EOF is
+	// an allowed error.
+	b := [][]byte{{}}
+	if _, err := r.ReadVec(b); err != nil && err != io.EOF {
+		t.Fatalf("error reading from socket connection: %v", err)
+	}
+
+	// We should have gotten a control message.
+	fds, err := r.ExtractFDs()
+	if err != nil {
+		t.Fatalf("error extracting fds from socket connection: %v", err)
+	}
+	if len(fds) != 1 {
+		t.Fatalf("got %d fds from socket, wanted 1", len(fds))
+	}
+
+	// Verify that the fd is a terminal.
+	if _, err := unix.IoctlGetTermios(fds[0], unix.TCGETS); err != nil {
+		t.Errorf("fd is not a terminal (ioctl TGGETS got %v)", err)
+	}
+
+	// Shut it down.
+	if err := s.Destroy(); err != nil {
+		t.Fatalf("error destroying container: %v", err)
+	}
+
+	// Close socket.
+	if err := srv.Close(); err != nil {
+		t.Fatalf("error destroying container: %v", err)
+	}
+}
+
+func TestSpecUnsupported(t *testing.T) {
+	spec := newSpecWithArgs("/bin/true")
+	spec.Process.SelinuxLabel = "somelabel"
+
+	// These are normally set by docker and will just cause warnings to be logged.
+	spec.Process.ApparmorProfile = "someprofile"
+	spec.Linux = &specs.Linux{Seccomp: &specs.LinuxSeccomp{}}
+
+	rootDir, bundleDir, conf, err := setupContainer(spec)
+	if err != nil {
+		t.Fatalf("error setting up container: %v", err)
+	}
+	defer os.RemoveAll(rootDir)
+	defer os.RemoveAll(bundleDir)
+
+	id := uniqueContainerID()
+	_, err = container.Create(id, spec, conf, bundleDir, "", "")
+	if err == nil || !strings.Contains(err.Error(), "is not supported") {
+		t.Errorf("container.Create() wrong error, got: %v, want: *is not supported, spec.Process: %+v", err, spec.Process)
+	}
+}
+
+// procListsEqual is used to check whether 2 Process lists are equal for all
+// implemented fields.
+func procListsEqual(got, want []*control.Process) bool {
+	if len(got) != len(want) {
+		return false
+	}
+	for i := range got {
+		pd1 := got[i]
+		pd2 := want[i]
+		// Zero out unimplemented and timing dependant fields.
+		pd1.Time, pd2.Time = "", ""
+		pd1.STime, pd2.STime = "", ""
+		pd1.C, pd2.C = 0, 0
+		if *pd1 != *pd2 {
+			return false
+		}
+	}
+	return true
+}
+
+func procListToString(pl []*control.Process) string {
+	strs := make([]string, 0, len(pl))
+	for _, p := range pl {
+		strs = append(strs, fmt.Sprintf("%+v", p))
+	}
+	return fmt.Sprintf("[%s]", strings.Join(strs, ","))
+}
+
+// TestMain acts like runsc if it is called with the "boot" argument, otherwise
+// it just runs the tests.  This is required because creating a container will
+// call "/proc/self/exe boot".  Normally /proc/self/exe is the runsc binary,
+// but for tests we have to fake it.
+func TestMain(m *testing.M) {
+	// exit writes coverage data before exiting.
+	exit := func(status int) {
+		os.Exit(status)
+	}
+
+	if !flag.Parsed() {
+		flag.Parse()
+	}
+
+	// If we are passed one of the commands then run it.
+	subcommands.Register(new(cmd.Boot), "boot")
+	subcommands.Register(new(cmd.Gofer), "gofer")
+	switch flag.Arg(0) {
+	case "boot", "gofer":
+		// Run the command in a goroutine so we can block the main
+		// thread waiting for shutdownSignal.
+		go func() {
+			conf := &boot.Config{
+				RootDir: "unused-root-dir",
+				Network: boot.NetworkNone,
+			}
+			var ws syscall.WaitStatus
+			subcmdCode := subcommands.Execute(context.Background(), conf, &ws)
+			if subcmdCode != subcommands.ExitSuccess {
+				panic(fmt.Sprintf("command failed to execute, err: %v", subcmdCode))
+			}
+			// Container exited normally. Shut down this process.
+			os.Exit(ws.ExitStatus())
+		}()
+
+		// Shutdown cleanly when the shutdownSignal is received.  This
+		// allows us to write coverage data before exiting.
+		sigc := make(chan os.Signal, 1)
+		signal.Notify(sigc, shutdownSignal)
+		<-sigc
+		exit(0)
+	default:
+		// Otherwise run the tests.
+		exit(m.Run())
+	}
+}