package fs
import (
"errors"
"fmt"
"os"
"sync"
"golang.org/x/sys/unix"
"github.com/opencontainers/runc/libcontainer/cgroups"
"github.com/opencontainers/runc/libcontainer/cgroups/fscommon"
"github.com/opencontainers/runc/libcontainer/configs"
)
var subsystems = []subsystem{
&CpusetGroup{},
&DevicesGroup{},
&MemoryGroup{},
&CpuGroup{},
&CpuacctGroup{},
&PidsGroup{},
&BlkioGroup{},
&HugetlbGroup{},
&NetClsGroup{},
&NetPrioGroup{},
&PerfEventGroup{},
&FreezerGroup{},
&RdmaGroup{},
&NameGroup{GroupName: "name=systemd", Join: true},
&NameGroup{GroupName: "misc", Join: true},
}
var errSubsystemDoesNotExist = errors.New("cgroup: subsystem does not exist")
func init() {
// If using cgroups-hybrid mode then add a "" controller indicating
// it should join the cgroups v2.
if cgroups.IsCgroup2HybridMode() {
subsystems = append(subsystems, &NameGroup{GroupName: "", Join: true})
}
}
type subsystem interface {
// Name returns the name of the subsystem.
Name() string
// GetStats fills in the stats for the subsystem.
GetStats(path string, stats *cgroups.Stats) error
// Apply creates and joins a cgroup, adding pid into it. Some
// subsystems use resources to pre-configure the cgroup parents
// before creating or joining it.
Apply(path string, r *configs.Resources, pid int) error
// Set sets the cgroup resources.
Set(path string, r *configs.Resources) error
}
type manager struct {
mu sync.Mutex
cgroups *configs.Cgroup
paths map[string]string
}
func NewManager(cg *configs.Cgroup, paths map[string]string) (cgroups.Manager, error) {
// Some v1 controllers (cpu, cpuset, and devices) expect
// cgroups.Resources to not be nil in Apply.
if cg.Resources == nil {
return nil, errors.New("cgroup v1 manager needs configs.Resources to be set during manager creation")
}
if cg.Resources.Unified != nil {
return nil, cgroups.ErrV1NoUnified
}
if paths == nil {
var err error
paths, err = initPaths(cg)
if err != nil {
return nil, err
}
}
return &manager{
cgroups: cg,
paths: paths,
}, nil
}
// isIgnorableError returns whether err is a permission error (in the loose
// sense of the word). This includes EROFS (which for an unprivileged user is
// basically a permission error) and EACCES (for similar reasons) as well as
// the normal EPERM.
func isIgnorableError(rootless bool, err error) bool {
// We do not ignore errors if we are root.
if !rootless {
return false
}
// Is it an ordinary EPERM?
if errors.Is(err, os.ErrPermission) {
return true
}
// Handle some specific syscall errors.
var errno unix.Errno
if errors.As(err, &errno) {
return errno == unix.EROFS || errno == unix.EPERM || errno == unix.EACCES
}
return false
}
func (m *manager) Apply(pid int) (err error) {
m.mu.Lock()
defer m.mu.Unlock()
c := m.cgroups
for _, sys := range subsystems {
name := sys.Name()
p, ok := m.paths[name]
if !ok {
continue
}
if err := sys.Apply(p, c.Resources, pid); err != nil {
// In the case of rootless (including euid=0 in userns), where an
// explicit cgroup path hasn't been set, we don't bail on error in
// case of permission problems here, but do delete the path from
// the m.paths map, since it is either non-existent and could not
// be created, or the pid could not be added to it.
//
// Cases where limits for the subsystem have been set are handled
// later by Set, which fails with a friendly error (see
// if path == "" in Set).
if isIgnorableError(c.Rootless, err) && c.Path == "" {
delete(m.paths, name)
continue
}
return err
}
}
return nil
}
func (m *manager) Destroy() error {
m.mu.Lock()
defer m.mu.Unlock()
return cgroups.RemovePaths(m.paths)
}
func (m *manager) Path(subsys string) string {
m.mu.Lock()
defer m.mu.Unlock()
return m.paths[subsys]
}
func (m *manager) GetStats() (*cgroups.Stats, error) {
m.mu.Lock()
defer m.mu.Unlock()
stats := cgroups.NewStats()
for _, sys := range subsystems {
path := m.paths[sys.Name()]
if path == "" {
continue
}
if err := sys.GetStats(path, stats); err != nil {
return nil, err
}
}
return stats, nil
}
func (m *manager) Set(r *configs.Resources) error {
if r == nil {
return nil
}
if r.Unified != nil {
return cgroups.ErrV1NoUnified
}
m.mu.Lock()
defer m.mu.Unlock()
for _, sys := range subsystems {
path := m.paths[sys.Name()]
if err := sys.Set(path, r); err != nil {
// When rootless is true, errors from the device subsystem
// are ignored, as it is really not expected to work.
if m.cgroups.Rootless && sys.Name() == "devices" {
continue
}
// However, errors from other subsystems are not ignored.
// see @test "runc create (rootless + limits + no cgrouppath + no permission) fails with informative error"
if path == "" {
// We never created a path for this cgroup, so we cannot set
// limits for it (though we have already tried at this point).
return fmt.Errorf("cannot set %s limit: container could not join or create cgroup", sys.Name())
}
return err
}
}
return nil
}
// Freeze toggles the container's freezer cgroup depending on the state
// provided
func (m *manager) Freeze(state configs.FreezerState) error {
path := m.Path("freezer")
if path == "" {
return errors.New("cannot toggle freezer: cgroups not configured for container")
}
prevState := m.cgroups.Resources.Freezer
m.cgroups.Resources.Freezer = state
freezer := &FreezerGroup{}
if err := freezer.Set(path, m.cgroups.Resources); err != nil {
m.cgroups.Resources.Freezer = prevState
return err
}
return nil
}
func (m *manager) GetPids() ([]int, error) {
return cgroups.GetPids(m.Path("devices"))
}
func (m *manager) GetAllPids() ([]int, error) {
return cgroups.GetAllPids(m.Path("devices"))
}
func (m *manager) GetPaths() map[string]string {
m.mu.Lock()
defer m.mu.Unlock()
return m.paths
}
func (m *manager) GetCgroups() (*configs.Cgroup, error) {
return m.cgroups, nil
}
func (m *manager) GetFreezerState() (configs.FreezerState, error) {
dir := m.Path("freezer")
// If the container doesn't have the freezer cgroup, say it's undefined.
if dir == "" {
return configs.Undefined, nil
}
freezer := &FreezerGroup{}
return freezer.GetState(dir)
}
func (m *manager) Exists() bool {
return cgroups.PathExists(m.Path("devices"))
}
func OOMKillCount(path string) (uint64, error) {
return fscommon.GetValueByKey(path, "memory.oom_control", "oom_kill")
}
func (m *manager) OOMKillCount() (uint64, error) {
c, err := OOMKillCount(m.Path("memory"))
// Ignore ENOENT when rootless as it couldn't create cgroup.
if err != nil && m.cgroups.Rootless && os.IsNotExist(err) {
err = nil
}
return c, err
}
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