cgroup v1 and v2 kernel config check according to isCgroupV2

validators/cgroup_validator_other.go

@@ -23,6 +23,8 @@ package system
 
 var _ Validator = &CgroupsValidator{}
 
+const mountsFilePath = ""
+
 // CgroupsValidator validates cgroup configuration.
 type CgroupsValidator struct {
 	Reporter Reporter
@@ -37,3 +39,8 @@ func (c *CgroupsValidator) Validate(spec SysSpec) (warns, errs []error) {
 func (c *CgroupsValidator) Name() string {
 	return "cgroups"
 }
+
+// getUnifiedMountpoint is a no-op for non-Linux OSes.
+func getUnifiedMountpoint(path string) (string, bool, error) {
+	return "", false, nil
+}

validators/kernel_validator.go

@@ -70,7 +70,8 @@ func (k *KernelValidator) Validate(spec SysSpec) ([]error, []error) {
 		warns = append(warns, warn)
 	}
 	// only validate kernel config when necessary (currently no kernel config for windows)
-	if len(spec.KernelSpec.Required) > 0 || len(spec.KernelSpec.Forbidden) > 0 || len(spec.KernelSpec.Optional) > 0 {
+	if len(spec.KernelSpec.Required) > 0 || len(spec.KernelSpec.Forbidden) > 0 || len(spec.KernelSpec.Optional) > 0 ||
+		len(spec.KernelSpec.RequiredCgroupsV1) > 0 || len(spec.KernelSpec.RequiredCgroupsV2) > 0 {
 		if err = k.validateKernelConfig(spec.KernelSpec); err != nil {
 			errs = append(errs, err)
 		}
@@ -158,6 +159,20 @@ func (k *KernelValidator) validateCachedKernelConfig(allConfig map[string]kConfi
 	for _, config := range kSpec.Required {
 		validateOpt(config, required)
 	}
+	_, isCgroupsV2, err := getUnifiedMountpoint(mountsFilePath)
+	if err != nil {
+		return fmt.Errorf("failed to get unified mountpoint: %w", err)
+	}
+	if isCgroupsV2 {
+		for _, config := range kSpec.RequiredCgroupsV2 {
+			validateOpt(config, required)
+		}
+	} else {
+		for _, config := range kSpec.RequiredCgroupsV1 {
+			validateOpt(config, required)
+		}
+	}
+
 	for _, config := range kSpec.Optional {
 		validateOpt(config, optional)
 	}

validators/types.go

@@ -46,7 +46,12 @@ type KernelSpec struct {
 	VersionsNote string `json:"versionsNote,omitempty"`
 	// Required contains all kernel configurations required to be enabled
 	// (built in or as module).
+	// RequiredCgroupsV1 and RequiredCgroupsV2 are mutually exclusive.
 	Required []KernelConfig `json:"required,omitempty"`
+	// RequiredCgroupsV1 contains all kernel configurations required to be enabled for cgroups v1.
+	RequiredCgroupsV1 []KernelConfig `json:"requiredCgroupsV1,omitempty"`
+	// RequiredCgroupsV2 contains all kernel configurations required to be enabled for cgroups v2.
+	RequiredCgroupsV2 []KernelConfig `json:"requiredCgroupsV2,omitempty"`
 	// Optional contains all kernel configurations are required for optional
 	// features.
 	Optional []KernelConfig `json:"optional,omitempty"`

validators/types_unix.go

@@ -41,7 +41,6 @@ var DefaultSysSpec = SysSpec{
 			{Name: "PID_NS"},
 			{Name: "IPC_NS"},
 			{Name: "UTS_NS"},
-			{Name: "CGROUPS"},
 			{Name: "CPUSETS"},
 			{Name: "MEMCG"},
 			{Name: "INET"},
@@ -51,6 +50,20 @@ var DefaultSysSpec = SysSpec{
 			{Name: "NETFILTER_XT_MATCH_COMMENT"},
 			{Name: "FAIR_GROUP_SCHED"},
 		},
+		RequiredCgroupsV1: []KernelConfig{
+			{Name: "CGROUPS", Description: "Required for cgroups."},
+			{Name: "CGROUP_CPUACCT", Description: "Required for cpuacct controller, used in simple CPU accounting controller."},
+			{Name: "CGROUP_DEVICE", Description: "Required for device controller."},
+			{Name: "CGROUP_FREEZER", Description: "Required for freezer controller."},
+			{Name: "CGROUP_PIDS", Description: "Required for PIDs controller."},
+			{Name: "CGROUP_SCHED", Description: "Required for CPU controller."},
+		},
+		RequiredCgroupsV2: []KernelConfig{
+			{Name: "CGROUPS", Description: "Required for cgroups."},
+			{Name: "CGROUP_BPF", Description: "Required for eBPF programs attached to cgroups, used in device controller."},
+			{Name: "CGROUP_PIDS", Description: "Required for PIDs controller."},
+			{Name: "CGROUP_SCHED", Description: "Required for CPU controller."},
+		},
 		Optional: []KernelConfig{
 			{Name: "OVERLAY_FS", Aliases: []string{"OVERLAYFS_FS"}, Description: "Required for overlayfs."},
 			{Name: "AUFS_FS", Description: "Required for aufs."},