package cgroups import ( "bufio" "bytes" "fmt" "io/ioutil" "math" "os" "path/filepath" "strconv" "strings" "github.com/containers/podman/v3/pkg/rootless" systemdDbus "github.com/coreos/go-systemd/v22/dbus" "github.com/godbus/dbus/v5" spec "github.com/opencontainers/runtime-spec/specs-go" "github.com/pkg/errors" "github.com/sirupsen/logrus" ) var ( // ErrCgroupDeleted means the cgroup was deleted ErrCgroupDeleted = errors.New("cgroup deleted") // ErrCgroupV1Rootless means the cgroup v1 were attempted to be used in rootless environment ErrCgroupV1Rootless = errors.New("no support for CGroups V1 in rootless environments") ErrStatCgroup = errors.New("no cgroup available for gathering user statistics") ) // CgroupControl controls a cgroup hierarchy type CgroupControl struct { cgroup2 bool path string systemd bool // List of additional cgroup subsystems joined that // do not have a custom handler. additionalControllers []controller } // CPUUsage keeps stats for the CPU usage (unit: nanoseconds) type CPUUsage struct { Kernel uint64 Total uint64 PerCPU []uint64 } // MemoryUsage keeps stats for the memory usage type MemoryUsage struct { Usage uint64 Limit uint64 } // CPUMetrics keeps stats for the CPU usage type CPUMetrics struct { Usage CPUUsage } // BlkIOEntry describes an entry in the blkio stats type BlkIOEntry struct { Op string Major uint64 Minor uint64 Value uint64 } // BlkioMetrics keeps usage stats for the blkio cgroup controller type BlkioMetrics struct { IoServiceBytesRecursive []BlkIOEntry } // MemoryMetrics keeps usage stats for the memory cgroup controller type MemoryMetrics struct { Usage MemoryUsage } // PidsMetrics keeps usage stats for the pids cgroup controller type PidsMetrics struct { Current uint64 } // Metrics keeps usage stats for the cgroup controllers type Metrics struct { CPU CPUMetrics Blkio BlkioMetrics Memory MemoryMetrics Pids PidsMetrics } type controller struct { name string symlink bool } type controllerHandler interface { Create(*CgroupControl) (bool, error) Apply(*CgroupControl, *spec.LinuxResources) error Destroy(*CgroupControl) error Stat(*CgroupControl, *Metrics) error } const ( cgroupRoot = "/sys/fs/cgroup" // CPU is the cpu controller CPU = "cpu" // CPUAcct is the cpuacct controller CPUAcct = "cpuacct" // CPUset is the cpuset controller CPUset = "cpuset" // Memory is the memory controller Memory = "memory" // Pids is the pids controller Pids = "pids" // Blkio is the blkio controller Blkio = "blkio" ) var handlers map[string]controllerHandler func init() { handlers = make(map[string]controllerHandler) handlers[CPU] = getCPUHandler() handlers[CPUset] = getCpusetHandler() handlers[Memory] = getMemoryHandler() handlers[Pids] = getPidsHandler() handlers[Blkio] = getBlkioHandler() } // getAvailableControllers get the available controllers func getAvailableControllers(exclude map[string]controllerHandler, cgroup2 bool) ([]controller, error) { if cgroup2 { controllers := []controller{} subtreeControl := cgroupRoot + "/cgroup.subtree_control" // rootless cgroupv2: check available controllers for current user ,systemd or servicescope will inherit if rootless.IsRootless() { userSlice, err := getCgroupPathForCurrentProcess() if err != nil { return controllers, err } //userSlice already contains '/' so not adding here basePath := cgroupRoot + userSlice subtreeControl = fmt.Sprintf("%s/cgroup.subtree_control", basePath) } subtreeControlBytes, err := ioutil.ReadFile(subtreeControl) if err != nil { return nil, errors.Wrapf(err, "failed while reading controllers for cgroup v2 from %q", subtreeControl) } for _, controllerName := range strings.Fields(string(subtreeControlBytes)) { c := controller{ name: controllerName, symlink: false, } controllers = append(controllers, c) } return controllers, nil } subsystems, _ := cgroupV1GetAllSubsystems() controllers := []controller{} // cgroupv1 and rootless: No subsystem is available: delegation is unsafe. if rootless.IsRootless() { return controllers, nil } for _, name := range subsystems { if _, found := exclude[name]; found { continue } isSymLink := false fileInfo, err := os.Stat(cgroupRoot + "/" + name) if err != nil { isSymLink = !fileInfo.IsDir() } c := controller{ name: name, symlink: isSymLink, } controllers = append(controllers, c) } return controllers, nil } // GetAvailableControllers get string:bool map of all the available controllers func GetAvailableControllers(exclude map[string]controllerHandler, cgroup2 bool) ([]string, error) { availableControllers, err := getAvailableControllers(exclude, cgroup2) if err != nil { return nil, err } controllerList := []string{} for _, controller := range availableControllers { controllerList = append(controllerList, controller.name) } return controllerList, nil } func cgroupV1GetAllSubsystems() ([]string, error) { f, err := os.Open("/proc/cgroups") if err != nil { return nil, err } defer f.Close() subsystems := []string{} s := bufio.NewScanner(f) for s.Scan() { text := s.Text() if text[0] != '#' { parts := strings.Fields(text) if len(parts) >= 4 && parts[3] != "0" { subsystems = append(subsystems, parts[0]) } } } if err := s.Err(); err != nil { return nil, err } return subsystems, nil } func getCgroupPathForCurrentProcess() (string, error) { path := fmt.Sprintf("/proc/%d/cgroup", os.Getpid()) f, err := os.Open(path) if err != nil { return "", err } defer f.Close() cgroupPath := "" s := bufio.NewScanner(f) for s.Scan() { text := s.Text() procEntries := strings.SplitN(text, "::", 2) cgroupPath = procEntries[1] } if err := s.Err(); err != nil { return cgroupPath, err } return cgroupPath, nil } // getCgroupv1Path is a helper function to get the cgroup v1 path func (c *CgroupControl) getCgroupv1Path(name string) string { return filepath.Join(cgroupRoot, name, c.path) } // createCgroupv2Path creates the cgroupv2 path and enables all the available controllers func createCgroupv2Path(path string) (deferredError error) { if !strings.HasPrefix(path, cgroupRoot+"/") { return fmt.Errorf("invalid cgroup path %s", path) } content, err := ioutil.ReadFile(cgroupRoot + "/cgroup.controllers") if err != nil { return err } ctrs := bytes.Fields(content) res := append([]byte("+"), bytes.Join(ctrs, []byte(" +"))...) current := "/sys/fs" elements := strings.Split(path, "/") for i, e := range elements[3:] { current = filepath.Join(current, e) if i > 0 { if err := os.Mkdir(current, 0755); err != nil { if !os.IsExist(err) { return err } } else { // If the directory was created, be sure it is not left around on errors. defer func() { if deferredError != nil { os.Remove(current) } }() } } // We enable the controllers for all the path components except the last one. It is not allowed to add // PIDs if there are already enabled controllers. if i < len(elements[3:])-1 { if err := ioutil.WriteFile(filepath.Join(current, "cgroup.subtree_control"), res, 0755); err != nil { return err } } } return nil } // initialize initializes the specified hierarchy func (c *CgroupControl) initialize() (err error) { createdSoFar := map[string]controllerHandler{} defer func() { if err != nil { for name, ctr := range createdSoFar { if err := ctr.Destroy(c); err != nil { logrus.Warningf("error cleaning up controller %s for %s", name, c.path) } } } }() if c.cgroup2 { if err := createCgroupv2Path(filepath.Join(cgroupRoot, c.path)); err != nil { return errors.Wrapf(err, "error creating cgroup path %s", c.path) } } for name, handler := range handlers { created, err := handler.Create(c) if err != nil { return err } if created { createdSoFar[name] = handler } } if !c.cgroup2 { // We won't need to do this for cgroup v2 for _, ctr := range c.additionalControllers { if ctr.symlink { continue } path := c.getCgroupv1Path(ctr.name) if err := os.MkdirAll(path, 0755); err != nil { return errors.Wrapf(err, "error creating cgroup path for %s", ctr.name) } } } return nil } func (c *CgroupControl) createCgroupDirectory(controller string) (bool, error) { cPath := c.getCgroupv1Path(controller) _, err := os.Stat(cPath) if err == nil { return false, nil } if !os.IsNotExist(err) { return false, err } if err := os.MkdirAll(cPath, 0755); err != nil { return false, errors.Wrapf(err, "error creating cgroup for %s", controller) } return true, nil } func readFileAsUint64(path string) (uint64, error) { data, err := ioutil.ReadFile(path) if err != nil { return 0, err } v := cleanString(string(data)) if v == "max" { return math.MaxUint64, nil } ret, err := strconv.ParseUint(v, 10, 64) if err != nil { return ret, errors.Wrapf(err, "parse %s from %s", v, path) } return ret, nil } // New creates a new cgroup control func New(path string, resources *spec.LinuxResources) (*CgroupControl, error) { cgroup2, err := IsCgroup2UnifiedMode() if err != nil { return nil, err } control := &CgroupControl{ cgroup2: cgroup2, path: path, } if !cgroup2 { controllers, err := getAvailableControllers(handlers, false) if err != nil { return nil, err } control.additionalControllers = controllers } if err := control.initialize(); err != nil { return nil, err } return control, nil } // NewSystemd creates a new cgroup control func NewSystemd(path string) (*CgroupControl, error) { cgroup2, err := IsCgroup2UnifiedMode() if err != nil { return nil, err } control := &CgroupControl{ cgroup2: cgroup2, path: path, systemd: true, } return control, nil } // Load loads an existing cgroup control func Load(path string) (*CgroupControl, error) { cgroup2, err := IsCgroup2UnifiedMode() if err != nil { return nil, err } control := &CgroupControl{ cgroup2: cgroup2, path: path, systemd: false, } if !cgroup2 { controllers, err := getAvailableControllers(handlers, false) if err != nil { return nil, err } control.additionalControllers = controllers } if !cgroup2 { oneExists := false // check that the cgroup exists at least under one controller for name := range handlers { p := control.getCgroupv1Path(name) if _, err := os.Stat(p); err == nil { oneExists = true break } } // if there is no controller at all, raise an error if !oneExists { if rootless.IsRootless() { return nil, ErrCgroupV1Rootless } // compatible with the error code // used by containerd/cgroups return nil, ErrCgroupDeleted } } return control, nil } // CreateSystemdUnit creates the systemd cgroup func (c *CgroupControl) CreateSystemdUnit(path string) error { if !c.systemd { return fmt.Errorf("the cgroup controller is not using systemd") } conn, err := systemdDbus.New() if err != nil { return err } defer conn.Close() return systemdCreate(path, conn) } // GetUserConnection returns an user connection to D-BUS func GetUserConnection(uid int) (*systemdDbus.Conn, error) { return systemdDbus.NewConnection(func() (*dbus.Conn, error) { return dbusAuthConnection(uid, dbus.SessionBusPrivate) }) } // CreateSystemdUserUnit creates the systemd cgroup for the specified user func (c *CgroupControl) CreateSystemdUserUnit(path string, uid int) error { if !c.systemd { return fmt.Errorf("the cgroup controller is not using systemd") } conn, err := GetUserConnection(uid) if err != nil { return err } defer conn.Close() return systemdCreate(path, conn) } func dbusAuthConnection(uid int, createBus func(opts ...dbus.ConnOption) (*dbus.Conn, error)) (*dbus.Conn, error) { conn, err := createBus() if err != nil { return nil, err } methods := []dbus.Auth{dbus.AuthExternal(strconv.Itoa(uid))} err = conn.Auth(methods) if err != nil { conn.Close() return nil, err } if err := conn.Hello(); err != nil { return nil, err } return conn, nil } // Delete cleans a cgroup func (c *CgroupControl) Delete() error { return c.DeleteByPath(c.path) } // rmDirRecursively delete recursively a cgroup directory. // It differs from os.RemoveAll as it doesn't attempt to unlink files. // On cgroupfs we are allowed only to rmdir empty directories. func rmDirRecursively(path string) error { if err := os.Remove(path); err == nil || os.IsNotExist(err) { return nil } entries, err := ioutil.ReadDir(path) if err != nil { return err } for _, i := range entries { if i.IsDir() { if err := rmDirRecursively(filepath.Join(path, i.Name())); err != nil { return err } } } if err := os.Remove(path); err != nil { if !os.IsNotExist(err) { return errors.Wrapf(err, "remove %s", path) } } return nil } // DeleteByPathConn deletes the specified cgroup path using the specified // dbus connection if needed. func (c *CgroupControl) DeleteByPathConn(path string, conn *systemdDbus.Conn) error { if c.systemd { return systemdDestroyConn(path, conn) } if c.cgroup2 { return rmDirRecursively(filepath.Join(cgroupRoot, c.path)) } var lastError error for _, h := range handlers { if err := h.Destroy(c); err != nil { lastError = err } } for _, ctr := range c.additionalControllers { if ctr.symlink { continue } p := c.getCgroupv1Path(ctr.name) if err := rmDirRecursively(p); err != nil { lastError = errors.Wrapf(err, "remove %s", p) } } return lastError } // DeleteByPath deletes the specified cgroup path func (c *CgroupControl) DeleteByPath(path string) error { if c.systemd { conn, err := systemdDbus.New() if err != nil { return err } defer conn.Close() return c.DeleteByPathConn(path, conn) } return c.DeleteByPathConn(path, nil) } // Update updates the cgroups func (c *CgroupControl) Update(resources *spec.LinuxResources) error { for _, h := range handlers { if err := h.Apply(c, resources); err != nil { return err } } return nil } // AddPid moves the specified pid to the cgroup func (c *CgroupControl) AddPid(pid int) error { pidString := []byte(fmt.Sprintf("%d\n", pid)) if c.cgroup2 { p := filepath.Join(cgroupRoot, c.path, "cgroup.procs") if err := ioutil.WriteFile(p, pidString, 0644); err != nil { return errors.Wrapf(err, "write %s", p) } return nil } names := make([]string, 0, len(handlers)) for n := range handlers { names = append(names, n) } for _, c := range c.additionalControllers { if !c.symlink { names = append(names, c.name) } } for _, n := range names { // If we aren't using cgroup2, we won't write correctly to unified hierarchy if !c.cgroup2 && n == "unified" { continue } p := filepath.Join(c.getCgroupv1Path(n), "tasks") if err := ioutil.WriteFile(p, pidString, 0644); err != nil { return errors.Wrapf(err, "write %s", p) } } return nil } // Stat returns usage statistics for the cgroup func (c *CgroupControl) Stat() (*Metrics, error) { m := Metrics{} found := false for _, h := range handlers { if err := h.Stat(c, &m); err != nil { if !os.IsNotExist(errors.Cause(err)) { return nil, err } logrus.Warningf("Failed to retrieve cgroup stats: %v", err) continue } found = true } if !found { return nil, ErrStatCgroup } return &m, nil } func readCgroup2MapPath(path string) (map[string][]string, error) { ret := map[string][]string{} f, err := os.Open(path) if err != nil { if os.IsNotExist(err) { return ret, nil } return nil, errors.Wrapf(err, "open file %s", path) } defer f.Close() scanner := bufio.NewScanner(f) for scanner.Scan() { line := scanner.Text() parts := strings.Fields(line) if len(parts) < 2 { continue } ret[parts[0]] = parts[1:] } if err := scanner.Err(); err != nil { return nil, errors.Wrapf(err, "parsing file %s", path) } return ret, nil } func readCgroup2MapFile(ctr *CgroupControl, name string) (map[string][]string, error) { p := filepath.Join(cgroupRoot, ctr.path, name) return readCgroup2MapPath(p) }