diff --git a/libcontainer/cgroups/fs/freezer.go b/libcontainer/cgroups/fs/freezer.go index 519bd5136..4baa2798a 100644 --- a/libcontainer/cgroups/fs/freezer.go +++ b/libcontainer/cgroups/fs/freezer.go @@ -129,7 +129,25 @@ func (s *FreezerGroup) GetState(path string) (configs.FreezerState, error) { case "THAWED": return configs.Thawed, nil case "FROZEN": - return configs.Frozen, nil + // Find out whether the cgroup is frozen directly, + // or indirectly via an ancestor. + self, err := cgroups.ReadFile(path, "freezer.self_freezing") + if err != nil { + // If the kernel is too old, then we just treat + // it as being frozen. + if errors.Is(err, os.ErrNotExist) || errors.Is(err, unix.ENODEV) { + err = nil + } + return configs.Frozen, err + } + switch self { + case "0\n": + return configs.Thawed, nil + case "1\n": + return configs.Frozen, nil + default: + return configs.Undefined, fmt.Errorf(`unknown "freezer.self_freezing" state: %q`, self) + } case "FREEZING": // Make sure we get a stable freezer state, so retry if the cgroup // is still undergoing freezing. This should be a temporary delay. diff --git a/libcontainer/cgroups/systemd/systemd_test.go b/libcontainer/cgroups/systemd/systemd_test.go index cee176579..a444ff613 100644 --- a/libcontainer/cgroups/systemd/systemd_test.go +++ b/libcontainer/cgroups/systemd/systemd_test.go @@ -1,6 +1,7 @@ package systemd import ( + "bufio" "bytes" "os" "os/exec" @@ -193,3 +194,143 @@ func TestUnitExistsIgnored(t *testing.T) { } } } + +func TestFreezePodCgroup(t *testing.T) { + if !IsRunningSystemd() { + t.Skip("Test requires systemd.") + } + if os.Geteuid() != 0 { + t.Skip("Test requires root.") + } + + podConfig := &configs.Cgroup{ + Parent: "system.slice", + Name: "system-runc_test_pod.slice", + Resources: &configs.Resources{ + SkipDevices: true, + Freezer: configs.Frozen, + }, + } + // Create a "pod" cgroup (a systemd slice to hold containers), + // which is frozen initially. + pm := newManager(podConfig) + defer pm.Destroy() //nolint:errcheck + if err := pm.Apply(-1); err != nil { + t.Fatal(err) + } + + if err := pm.Freeze(configs.Frozen); err != nil { + t.Fatal(err) + } + if err := pm.Set(podConfig.Resources); err != nil { + t.Fatal(err) + } + + // Check the pod is frozen. + pf, err := pm.GetFreezerState() + if err != nil { + t.Fatal(err) + } + if pf != configs.Frozen { + t.Fatalf("expected pod to be frozen, got %v", pf) + } + + // Create a "container" within the "pod" cgroup. + // This is not a real container, just a process in the cgroup. + containerConfig := &configs.Cgroup{ + Parent: "system-runc_test_pod.slice", + ScopePrefix: "test", + Name: "inner-contianer", + Resources: &configs.Resources{}, + } + + cmd := exec.Command("bash", "-c", "while read; do echo $REPLY; done") + cmd.Env = append(os.Environ(), "LANG=C") + + // Setup stdin. + stdinR, stdinW, err := os.Pipe() + if err != nil { + t.Fatal(err) + } + cmd.Stdin = stdinR + + // Setup stdout. + stdoutR, stdoutW, err := os.Pipe() + if err != nil { + t.Fatal(err) + } + cmd.Stdout = stdoutW + rdr := bufio.NewReader(stdoutR) + + // Setup stderr. + var stderr bytes.Buffer + cmd.Stderr = &stderr + + err = cmd.Start() + stdinR.Close() + stdoutW.Close() + defer func() { + _ = stdinW.Close() + _ = stdoutR.Close() + }() + if err != nil { + t.Fatal(err) + } + // Make sure to not leave a zombie. + defer func() { + // These may fail, we don't care. + _ = cmd.Process.Kill() + _ = cmd.Wait() + }() + + // Put the process into a cgroup. + cm := newManager(containerConfig) + defer cm.Destroy() //nolint:errcheck + + if err := cm.Apply(cmd.Process.Pid); err != nil { + t.Fatal(err) + } + if err := cm.Set(containerConfig.Resources); err != nil { + t.Fatal(err) + } + // Check that we put the "container" into the "pod" cgroup. + if !strings.HasPrefix(cm.Path("freezer"), pm.Path("freezer")) { + t.Fatalf("expected container cgroup path %q to be under pod cgroup path %q", + cm.Path("freezer"), pm.Path("freezer")) + } + // Check the container is not reported as frozen despite the frozen parent. + cf, err := cm.GetFreezerState() + if err != nil { + t.Fatal(err) + } + if cf != configs.Thawed { + t.Fatalf("expected container to be thawed, got %v", cf) + } + + // Unfreeze the pod. + if err := pm.Freeze(configs.Thawed); err != nil { + t.Fatal(err) + } + + cf, err = cm.GetFreezerState() + if err != nil { + t.Fatal(err) + } + if cf != configs.Thawed { + t.Fatalf("expected container to be thawed, got %v", cf) + } + + // Check the "container" works. + marker := "one two\n" + _, err = stdinW.WriteString(marker) + if err != nil { + t.Fatal(err) + } + reply, err := rdr.ReadString('\n') + if err != nil { + t.Fatalf("reading from container: %v", err) + } + if reply != marker { + t.Fatalf("expected %q, got %q", marker, reply) + } +}