@@ -607,6 +607,15 @@ func CreateCgroupConfig(opts *CreateOpts, defaultDevs []*devices.Device) (*confi
 					Limit:    l.Limit,
 				})
 			}
+			if len(r.Rdma) > 0 {
+				c.Resources.Rdma = make(map[string]configs.LinuxRdma, len(r.Rdma))
+				for k, v := range r.Rdma {
+					c.Resources.Rdma[k] = configs.LinuxRdma{
+						HcaHandles: v.HcaHandles,
+						HcaObjects: v.HcaObjects,
+					}
+				}
+			}
 			if r.Network != nil {
 				if r.Network.ClassID != nil {
 					c.Resources.NetClsClassid = *r.Network.ClassID
// +build linux

// Package specconv implements conversion of specifications to libcontainer
// configurations
package specconv

import (
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"time"

	systemdDbus "github.com/coreos/go-systemd/v22/dbus"
	dbus "github.com/godbus/dbus/v5"
	"github.com/opencontainers/runc/libcontainer/cgroups"
	"github.com/opencontainers/runc/libcontainer/configs"
	"github.com/opencontainers/runc/libcontainer/devices"
	"github.com/opencontainers/runc/libcontainer/seccomp"
	libcontainerUtils "github.com/opencontainers/runc/libcontainer/utils"
	"github.com/opencontainers/runtime-spec/specs-go"
	"github.com/sirupsen/logrus"

	"golang.org/x/sys/unix"
)

var namespaceMapping = map[specs.LinuxNamespaceType]configs.NamespaceType{
	specs.PIDNamespace:     configs.NEWPID,
	specs.NetworkNamespace: configs.NEWNET,
	specs.MountNamespace:   configs.NEWNS,
	specs.UserNamespace:    configs.NEWUSER,
	specs.IPCNamespace:     configs.NEWIPC,
	specs.UTSNamespace:     configs.NEWUTS,
	specs.CgroupNamespace:  configs.NEWCGROUP,
}

var mountPropagationMapping = map[string]int{
	"rprivate":    unix.MS_PRIVATE | unix.MS_REC,
	"private":     unix.MS_PRIVATE,
	"rslave":      unix.MS_SLAVE | unix.MS_REC,
	"slave":       unix.MS_SLAVE,
	"rshared":     unix.MS_SHARED | unix.MS_REC,
	"shared":      unix.MS_SHARED,
	"runbindable": unix.MS_UNBINDABLE | unix.MS_REC,
	"unbindable":  unix.MS_UNBINDABLE,
	"":            0,
}

// AllowedDevices is the set of devices which are automatically included for
// all containers.
//
// XXX (cyphar)
//    This behaviour is at the very least "questionable" (if not outright
//    wrong) according to the runtime-spec.
//
//    Yes, we have to include certain devices other than the ones the user
//    specifies, but several devices listed here are not part of the spec
//    (including "mknod for any device"?!). In addition, these rules are
//    appended to the user-provided set which means that users *cannot disable
//    this behaviour*.
//
//    ... unfortunately I'm too scared to change this now because who knows how
//    many people depend on this (incorrect and arguably insecure) behaviour.
var AllowedDevices = []*devices.Device{
	// allow mknod for any device
	{
		Rule: devices.Rule{
			Type:        devices.CharDevice,
			Major:       devices.Wildcard,
			Minor:       devices.Wildcard,
			Permissions: "m",
			Allow:       true,
		},
	},
	{
		Rule: devices.Rule{
			Type:        devices.BlockDevice,
			Major:       devices.Wildcard,
			Minor:       devices.Wildcard,
			Permissions: "m",
			Allow:       true,
		},
	},
	{
		Path:     "/dev/null",
		FileMode: 0o666,
		Uid:      0,
		Gid:      0,
		Rule: devices.Rule{
			Type:        devices.CharDevice,
			Major:       1,
			Minor:       3,
			Permissions: "rwm",
			Allow:       true,
		},
	},
	{
		Path:     "/dev/random",
		FileMode: 0o666,
		Uid:      0,
		Gid:      0,
		Rule: devices.Rule{
			Type:        devices.CharDevice,
			Major:       1,
			Minor:       8,
			Permissions: "rwm",
			Allow:       true,
		},
	},
	{
		Path:     "/dev/full",
		FileMode: 0o666,
		Uid:      0,
		Gid:      0,
		Rule: devices.Rule{
			Type:        devices.CharDevice,
			Major:       1,
			Minor:       7,
			Permissions: "rwm",
			Allow:       true,
		},
	},
	{
		Path:     "/dev/tty",
		FileMode: 0o666,
		Uid:      0,
		Gid:      0,
		Rule: devices.Rule{
			Type:        devices.CharDevice,
			Major:       5,
			Minor:       0,
			Permissions: "rwm",
			Allow:       true,
		},
	},
	{
		Path:     "/dev/zero",
		FileMode: 0o666,
		Uid:      0,
		Gid:      0,
		Rule: devices.Rule{
			Type:        devices.CharDevice,
			Major:       1,
			Minor:       5,
			Permissions: "rwm",
			Allow:       true,
		},
	},
	{
		Path:     "/dev/urandom",
		FileMode: 0o666,
		Uid:      0,
		Gid:      0,
		Rule: devices.Rule{
			Type:        devices.CharDevice,
			Major:       1,
			Minor:       9,
			Permissions: "rwm",
			Allow:       true,
		},
	},
	// /dev/pts/ - pts namespaces are "coming soon"
	{
		Rule: devices.Rule{
			Type:        devices.CharDevice,
			Major:       136,
			Minor:       devices.Wildcard,
			Permissions: "rwm",
			Allow:       true,
		},
	},
	{
		Rule: devices.Rule{
			Type:        devices.CharDevice,
			Major:       5,
			Minor:       2,
			Permissions: "rwm",
			Allow:       true,
		},
	},
	// tuntap
	{
		Rule: devices.Rule{
			Type:        devices.CharDevice,
			Major:       10,
			Minor:       200,
			Permissions: "rwm",
			Allow:       true,
		},
	},
}

type CreateOpts struct {
	CgroupName       string
	UseSystemdCgroup bool
	NoPivotRoot      bool
	NoNewKeyring     bool
	Spec             *specs.Spec
	RootlessEUID     bool
	RootlessCgroups  bool
}

// CreateLibcontainerConfig creates a new libcontainer configuration from a
// given specification and a cgroup name
func CreateLibcontainerConfig(opts *CreateOpts) (*configs.Config, error) {
	// runc's cwd will always be the bundle path
	rcwd, err := os.Getwd()
	if err != nil {
		return nil, err
	}
	cwd, err := filepath.Abs(rcwd)
	if err != nil {
		return nil, err
	}
	spec := opts.Spec
	if spec.Root == nil {
		return nil, errors.New("Root must be specified")
	}
	rootfsPath := spec.Root.Path
	if !filepath.IsAbs(rootfsPath) {
		rootfsPath = filepath.Join(cwd, rootfsPath)
	}
	labels := []string{}
	for k, v := range spec.Annotations {
		labels = append(labels, k+"="+v)
	}
	config := &configs.Config{
		Rootfs:          rootfsPath,
		NoPivotRoot:     opts.NoPivotRoot,
		Readonlyfs:      spec.Root.Readonly,
		Hostname:        spec.Hostname,
		Labels:          append(labels, "bundle="+cwd),
		NoNewKeyring:    opts.NoNewKeyring,
		RootlessEUID:    opts.RootlessEUID,
		RootlessCgroups: opts.RootlessCgroups,
	}

	for _, m := range spec.Mounts {
		cm, err := createLibcontainerMount(cwd, m)
		if err != nil {
			return nil, fmt.Errorf("invalid mount %+v: %w", m, err)
		}
		config.Mounts = append(config.Mounts, cm)
	}

	defaultDevs, err := createDevices(spec, config)
	if err != nil {
		return nil, err
	}

	c, err := CreateCgroupConfig(opts, defaultDevs)
	if err != nil {
		return nil, err
	}

	config.Cgroups = c
	// set linux-specific config
	if spec.Linux != nil {
		var exists bool
		if config.RootPropagation, exists = mountPropagationMapping[spec.Linux.RootfsPropagation]; !exists {
			return nil, fmt.Errorf("rootfsPropagation=%v is not supported", spec.Linux.RootfsPropagation)
		}
		if config.NoPivotRoot && (config.RootPropagation&unix.MS_PRIVATE != 0) {
			return nil, errors.New("rootfsPropagation of [r]private is not safe without pivot_root")
		}

		for _, ns := range spec.Linux.Namespaces {
			t, exists := namespaceMapping[ns.Type]
			if !exists {
				return nil, fmt.Errorf("namespace %q does not exist", ns)
			}
			if config.Namespaces.Contains(t) {
				return nil, fmt.Errorf("malformed spec file: duplicated ns %q", ns)
			}
			config.Namespaces.Add(t, ns.Path)
		}
		if config.Namespaces.Contains(configs.NEWNET) && config.Namespaces.PathOf(configs.NEWNET) == "" {
			config.Networks = []*configs.Network{
				{
					Type: "loopback",
				},
			}
		}
		if config.Namespaces.Contains(configs.NEWUSER) {
			if err := setupUserNamespace(spec, config); err != nil {
				return nil, err
			}
		}
		config.MaskPaths = spec.Linux.MaskedPaths
		config.ReadonlyPaths = spec.Linux.ReadonlyPaths
		config.MountLabel = spec.Linux.MountLabel
		config.Sysctl = spec.Linux.Sysctl
		if spec.Linux.Seccomp != nil {
			seccomp, err := SetupSeccomp(spec.Linux.Seccomp)
			if err != nil {
				return nil, err
			}
			config.Seccomp = seccomp
		}
		if spec.Linux.IntelRdt != nil {
			config.IntelRdt = &configs.IntelRdt{
				L3CacheSchema: spec.Linux.IntelRdt.L3CacheSchema,
				MemBwSchema:   spec.Linux.IntelRdt.MemBwSchema,
			}
		}
	}
	if spec.Process != nil {
		config.OomScoreAdj = spec.Process.OOMScoreAdj
		config.NoNewPrivileges = spec.Process.NoNewPrivileges
		config.Umask = spec.Process.User.Umask
		config.ProcessLabel = spec.Process.SelinuxLabel
		if spec.Process.Capabilities != nil {
			config.Capabilities = &configs.Capabilities{
				Bounding:    spec.Process.Capabilities.Bounding,
				Effective:   spec.Process.Capabilities.Effective,
				Permitted:   spec.Process.Capabilities.Permitted,
				Inheritable: spec.Process.Capabilities.Inheritable,
				Ambient:     spec.Process.Capabilities.Ambient,
			}
		}
	}
	createHooks(spec, config)
	config.Version = specs.Version
	return config, nil
}

func createLibcontainerMount(cwd string, m specs.Mount) (*configs.Mount, error) {
	if !filepath.IsAbs(m.Destination) {
		// Relax validation for backward compatibility
		// TODO (runc v1.x.x): change warning to an error
		// return nil, fmt.Errorf("mount destination %s is not absolute", m.Destination)
		logrus.Warnf("mount destination %s is not absolute. Support for non-absolute mount destinations will be removed in a future release.", m.Destination)
	}
	flags, pgflags, data, ext := parseMountOptions(m.Options)
	source := m.Source
	device := m.Type
	if flags&unix.MS_BIND != 0 {
		// Any "type" the user specified is meaningless (and ignored) for
		// bind-mounts -- so we set it to "bind" because rootfs_linux.go
		// (incorrectly) relies on this for some checks.
		device = "bind"
		if !filepath.IsAbs(source) {
			source = filepath.Join(cwd, m.Source)
		}
	}
	return &configs.Mount{
		Device:           device,
		Source:           source,
		Destination:      m.Destination,
		Data:             data,
		Flags:            flags,
		PropagationFlags: pgflags,
		Extensions:       ext,
	}, nil
}

// systemd property name check: latin letters only, at least 3 of them
var isValidName = regexp.MustCompile(`^[a-zA-Z]{3,}$`).MatchString

var isSecSuffix = regexp.MustCompile(`[a-z]Sec$`).MatchString

// Some systemd properties are documented as having "Sec" suffix
// (e.g. TimeoutStopSec) but are expected to have "USec" suffix
// here, so let's provide conversion to improve compatibility.
func convertSecToUSec(value dbus.Variant) (dbus.Variant, error) {
	var sec uint64
	const M = 1000000
	vi := value.Value()
	switch value.Signature().String() {
	case "y":
		sec = uint64(vi.(byte)) * M
	case "n":
		sec = uint64(vi.(int16)) * M
	case "q":
		sec = uint64(vi.(uint16)) * M
	case "i":
		sec = uint64(vi.(int32)) * M
	case "u":
		sec = uint64(vi.(uint32)) * M
	case "x":
		sec = uint64(vi.(int64)) * M
	case "t":
		sec = vi.(uint64) * M
	case "d":
		sec = uint64(vi.(float64) * M)
	default:
		return value, errors.New("not a number")
	}
	return dbus.MakeVariant(sec), nil
}

func initSystemdProps(spec *specs.Spec) ([]systemdDbus.Property, error) {
	const keyPrefix = "org.systemd.property."
	var sp []systemdDbus.Property

	for k, v := range spec.Annotations {
		name := strings.TrimPrefix(k, keyPrefix)
		if len(name) == len(k) { // prefix not there
			continue
		}
		if !isValidName(name) {
			return nil, fmt.Errorf("Annotation %s name incorrect: %s", k, name)
		}
		value, err := dbus.ParseVariant(v, dbus.Signature{})
		if err != nil {
			return nil, fmt.Errorf("Annotation %s=%s value parse error: %w", k, v, err)
		}
		if isSecSuffix(name) {
			name = strings.TrimSuffix(name, "Sec") + "USec"
			value, err = convertSecToUSec(value)
			if err != nil {
				return nil, fmt.Errorf("Annotation %s=%s value parse error: %w", k, v, err)
			}
		}
		sp = append(sp, systemdDbus.Property{Name: name, Value: value})
	}

	return sp, nil
}

func CreateCgroupConfig(opts *CreateOpts, defaultDevs []*devices.Device) (*configs.Cgroup, error) {
	var (
		myCgroupPath string

		spec             = opts.Spec
		useSystemdCgroup = opts.UseSystemdCgroup
		name             = opts.CgroupName
	)

	c := &configs.Cgroup{
		Resources: &configs.Resources{},
	}

	if useSystemdCgroup {
		sp, err := initSystemdProps(spec)
		if err != nil {
			return nil, err
		}
		c.SystemdProps = sp
	}

	if spec.Linux != nil && spec.Linux.CgroupsPath != "" {
		if useSystemdCgroup {
			myCgroupPath = spec.Linux.CgroupsPath
		} else {
			myCgroupPath = libcontainerUtils.CleanPath(spec.Linux.CgroupsPath)
		}
	}

	if useSystemdCgroup {
		if myCgroupPath == "" {
			// Default for c.Parent is set by systemd cgroup drivers.
			c.ScopePrefix = "runc"
			c.Name = name
		} else {
			// Parse the path from expected "slice:prefix:name"
			// for e.g. "system.slice:docker:1234"
			parts := strings.Split(myCgroupPath, ":")
			if len(parts) != 3 {
				return nil, fmt.Errorf("expected cgroupsPath to be of format \"slice:prefix:name\" for systemd cgroups, got %q instead", myCgroupPath)
			}
			c.Parent = parts[0]
			c.ScopePrefix = parts[1]
			c.Name = parts[2]
		}
	} else {
		if myCgroupPath == "" {
			c.Name = name
		}
		c.Path = myCgroupPath
	}

	// In rootless containers, any attempt to make cgroup changes is likely to fail.
	// libcontainer will validate this but ignores the error.
	if spec.Linux != nil {
		r := spec.Linux.Resources
		if r != nil {
			for i, d := range spec.Linux.Resources.Devices {
				var (
					t     = "a"
					major = int64(-1)
					minor = int64(-1)
				)
				if d.Type != "" {
					t = d.Type
				}
				if d.Major != nil {
					major = *d.Major
				}
				if d.Minor != nil {
					minor = *d.Minor
				}
				if d.Access == "" {
					return nil, fmt.Errorf("device access at %d field cannot be empty", i)
				}
				dt, err := stringToCgroupDeviceRune(t)
				if err != nil {
					return nil, err
				}
				c.Resources.Devices = append(c.Resources.Devices, &devices.Rule{
					Type:        dt,
					Major:       major,
					Minor:       minor,
					Permissions: devices.Permissions(d.Access),
					Allow:       d.Allow,
				})
			}
			if r.Memory != nil {
				if r.Memory.Limit != nil {
					c.Resources.Memory = *r.Memory.Limit
				}
				if r.Memory.Reservation != nil {
					c.Resources.MemoryReservation = *r.Memory.Reservation
				}
				if r.Memory.Swap != nil {
					c.Resources.MemorySwap = *r.Memory.Swap
				}
				if r.Memory.Kernel != nil || r.Memory.KernelTCP != nil {
					logrus.Warn("Kernel memory settings are ignored and will be removed")
				}
				if r.Memory.Swappiness != nil {
					c.Resources.MemorySwappiness = r.Memory.Swappiness
				}
				if r.Memory.DisableOOMKiller != nil {
					c.Resources.OomKillDisable = *r.Memory.DisableOOMKiller
				}
			}
			if r.CPU != nil {
				if r.CPU.Shares != nil {
					c.Resources.CpuShares = *r.CPU.Shares

					// CpuWeight is used for cgroupv2 and should be converted
					c.Resources.CpuWeight = cgroups.ConvertCPUSharesToCgroupV2Value(c.Resources.CpuShares)
				}
				if r.CPU.Quota != nil {
					c.Resources.CpuQuota = *r.CPU.Quota
				}
				if r.CPU.Period != nil {
					c.Resources.CpuPeriod = *r.CPU.Period
				}
				if r.CPU.RealtimeRuntime != nil {
					c.Resources.CpuRtRuntime = *r.CPU.RealtimeRuntime
				}
				if r.CPU.RealtimePeriod != nil {
					c.Resources.CpuRtPeriod = *r.CPU.RealtimePeriod
				}
				c.Resources.CpusetCpus = r.CPU.Cpus
				c.Resources.CpusetMems = r.CPU.Mems
			}
			if r.Pids != nil {
				c.Resources.PidsLimit = r.Pids.Limit
			}
			if r.BlockIO != nil {
				if r.BlockIO.Weight != nil {
					c.Resources.BlkioWeight = *r.BlockIO.Weight
				}
				if r.BlockIO.LeafWeight != nil {
					c.Resources.BlkioLeafWeight = *r.BlockIO.LeafWeight
				}
				if r.BlockIO.WeightDevice != nil {
					for _, wd := range r.BlockIO.WeightDevice {
						var weight, leafWeight uint16
						if wd.Weight != nil {
							weight = *wd.Weight
						}
						if wd.LeafWeight != nil {
							leafWeight = *wd.LeafWeight
						}
						weightDevice := configs.NewWeightDevice(wd.Major, wd.Minor, weight, leafWeight)
						c.Resources.BlkioWeightDevice = append(c.Resources.BlkioWeightDevice, weightDevice)
					}
				}
				if r.BlockIO.ThrottleReadBpsDevice != nil {
					for _, td := range r.BlockIO.ThrottleReadBpsDevice {
						rate := td.Rate
						throttleDevice := configs.NewThrottleDevice(td.Major, td.Minor, rate)
						c.Resources.BlkioThrottleReadBpsDevice = append(c.Resources.BlkioThrottleReadBpsDevice, throttleDevice)
					}
				}
				if r.BlockIO.ThrottleWriteBpsDevice != nil {
					for _, td := range r.BlockIO.ThrottleWriteBpsDevice {
						rate := td.Rate
						throttleDevice := configs.NewThrottleDevice(td.Major, td.Minor, rate)
						c.Resources.BlkioThrottleWriteBpsDevice = append(c.Resources.BlkioThrottleWriteBpsDevice, throttleDevice)
					}
				}
				if r.BlockIO.ThrottleReadIOPSDevice != nil {
					for _, td := range r.BlockIO.ThrottleReadIOPSDevice {
						rate := td.Rate
						throttleDevice := configs.NewThrottleDevice(td.Major, td.Minor, rate)
						c.Resources.BlkioThrottleReadIOPSDevice = append(c.Resources.BlkioThrottleReadIOPSDevice, throttleDevice)
					}
				}
				if r.BlockIO.ThrottleWriteIOPSDevice != nil {
					for _, td := range r.BlockIO.ThrottleWriteIOPSDevice {
						rate := td.Rate
						throttleDevice := configs.NewThrottleDevice(td.Major, td.Minor, rate)
						c.Resources.BlkioThrottleWriteIOPSDevice = append(c.Resources.BlkioThrottleWriteIOPSDevice, throttleDevice)
					}
				}
			}
			for _, l := range r.HugepageLimits {
				c.Resources.HugetlbLimit = append(c.Resources.HugetlbLimit, &configs.HugepageLimit{
					Pagesize: l.Pagesize,
					Limit:    l.Limit,
				})
			}
			if r.Network != nil {
				if r.Network.ClassID != nil {
					c.Resources.NetClsClassid = *r.Network.ClassID
				}
				for _, m := range r.Network.Priorities {
					c.Resources.NetPrioIfpriomap = append(c.Resources.NetPrioIfpriomap, &configs.IfPrioMap{
						Interface: m.Name,
						Priority:  int64(m.Priority),
					})
				}
			}
			if len(r.Unified) > 0 {
				// copy the map
				c.Resources.Unified = make(map[string]string, len(r.Unified))
				for k, v := range r.Unified {
					c.Resources.Unified[k] = v
				}
			}
		}
	}

	// Append the default allowed devices to the end of the list.
	for _, device := range defaultDevs {
		c.Resources.Devices = append(c.Resources.Devices, &device.Rule)
	}
	return c, nil
}

func stringToCgroupDeviceRune(s string) (devices.Type, error) {
	switch s {
	case "a":
		return devices.WildcardDevice, nil
	case "b":
		return devices.BlockDevice, nil
	case "c":
		return devices.CharDevice, nil
	default:
		return 0, fmt.Errorf("invalid cgroup device type %q", s)
	}
}

func stringToDeviceRune(s string) (devices.Type, error) {
	switch s {
	case "p":
		return devices.FifoDevice, nil
	case "u", "c":
		return devices.CharDevice, nil
	case "b":
		return devices.BlockDevice, nil
	default:
		return 0, fmt.Errorf("invalid device type %q", s)
	}
}

func createDevices(spec *specs.Spec, config *configs.Config) ([]*devices.Device, error) {
	// If a spec device is redundant with a default device, remove that default
	// device (the spec one takes priority).
	dedupedAllowDevs := []*devices.Device{}

next:
	for _, ad := range AllowedDevices {
		if ad.Path != "" {
			for _, sd := range spec.Linux.Devices {
				if sd.Path == ad.Path {
					continue next
				}
			}
		}
		dedupedAllowDevs = append(dedupedAllowDevs, ad)
		if ad.Path != "" {
			config.Devices = append(config.Devices, ad)
		}
	}

	// Merge in additional devices from the spec.
	if spec.Linux != nil {
		for _, d := range spec.Linux.Devices {
			var uid, gid uint32
			var filemode os.FileMode = 0o666

			if d.UID != nil {
				uid = *d.UID
			}
			if d.GID != nil {
				gid = *d.GID
			}
			dt, err := stringToDeviceRune(d.Type)
			if err != nil {
				return nil, err
			}
			if d.FileMode != nil {
				filemode = *d.FileMode &^ unix.S_IFMT
			}
			device := &devices.Device{
				Rule: devices.Rule{
					Type:  dt,
					Major: d.Major,
					Minor: d.Minor,
				},
				Path:     d.Path,
				FileMode: filemode,
				Uid:      uid,
				Gid:      gid,
			}
			config.Devices = append(config.Devices, device)
		}
	}

	return dedupedAllowDevs, nil
}

func setupUserNamespace(spec *specs.Spec, config *configs.Config) error {
	create := func(m specs.LinuxIDMapping) configs.IDMap {
		return configs.IDMap{
			HostID:      int(m.HostID),
			ContainerID: int(m.ContainerID),
			Size:        int(m.Size),
		}
	}
	if spec.Linux != nil {
		for _, m := range spec.Linux.UIDMappings {
			config.UidMappings = append(config.UidMappings, create(m))
		}
		for _, m := range spec.Linux.GIDMappings {
			config.GidMappings = append(config.GidMappings, create(m))
		}
	}
	rootUID, err := config.HostRootUID()
	if err != nil {
		return err
	}
	rootGID, err := config.HostRootGID()
	if err != nil {
		return err
	}
	for _, node := range config.Devices {
		node.Uid = uint32(rootUID)
		node.Gid = uint32(rootGID)
	}
	return nil
}

// parseMountOptions parses the string and returns the flags, propagation
// flags and any mount data that it contains.
func parseMountOptions(options []string) (int, []int, string, int) {
	var (
		flag     int
		pgflag   []int
		data     []string
		extFlags int
	)
	flags := map[string]struct {
		clear bool
		flag  int
	}{
		"acl":           {false, unix.MS_POSIXACL},
		"async":         {true, unix.MS_SYNCHRONOUS},
		"atime":         {true, unix.MS_NOATIME},
		"bind":          {false, unix.MS_BIND},
		"defaults":      {false, 0},
		"dev":           {true, unix.MS_NODEV},
		"diratime":      {true, unix.MS_NODIRATIME},
		"dirsync":       {false, unix.MS_DIRSYNC},
		"exec":          {true, unix.MS_NOEXEC},
		"iversion":      {false, unix.MS_I_VERSION},
		"lazytime":      {false, unix.MS_LAZYTIME},
		"loud":          {true, unix.MS_SILENT},
		"mand":          {false, unix.MS_MANDLOCK},
		"noacl":         {true, unix.MS_POSIXACL},
		"noatime":       {false, unix.MS_NOATIME},
		"nodev":         {false, unix.MS_NODEV},
		"nodiratime":    {false, unix.MS_NODIRATIME},
		"noexec":        {false, unix.MS_NOEXEC},
		"noiversion":    {true, unix.MS_I_VERSION},
		"nolazytime":    {true, unix.MS_LAZYTIME},
		"nomand":        {true, unix.MS_MANDLOCK},
		"norelatime":    {true, unix.MS_RELATIME},
		"nostrictatime": {true, unix.MS_STRICTATIME},
		"nosuid":        {false, unix.MS_NOSUID},
		"rbind":         {false, unix.MS_BIND | unix.MS_REC},
		"relatime":      {false, unix.MS_RELATIME},
		"remount":       {false, unix.MS_REMOUNT},
		"ro":            {false, unix.MS_RDONLY},
		"rw":            {true, unix.MS_RDONLY},
		"silent":        {false, unix.MS_SILENT},
		"strictatime":   {false, unix.MS_STRICTATIME},
		"suid":          {true, unix.MS_NOSUID},
		"sync":          {false, unix.MS_SYNCHRONOUS},
	}
	propagationFlags := map[string]int{
		"private":     unix.MS_PRIVATE,
		"shared":      unix.MS_SHARED,
		"slave":       unix.MS_SLAVE,
		"unbindable":  unix.MS_UNBINDABLE,
		"rprivate":    unix.MS_PRIVATE | unix.MS_REC,
		"rshared":     unix.MS_SHARED | unix.MS_REC,
		"rslave":      unix.MS_SLAVE | unix.MS_REC,
		"runbindable": unix.MS_UNBINDABLE | unix.MS_REC,
	}
	extensionFlags := map[string]struct {
		clear bool
		flag  int
	}{
		"tmpcopyup": {false, configs.EXT_COPYUP},
	}
	for _, o := range options {
		// If the option does not exist in the flags table or the flag
		// is not supported on the platform,
		// then it is a data value for a specific fs type
		if f, exists := flags[o]; exists && f.flag != 0 {
			if f.clear {
				flag &= ^f.flag
			} else {
				flag |= f.flag
			}
		} else if f, exists := propagationFlags[o]; exists && f != 0 {
			pgflag = append(pgflag, f)
		} else if f, exists := extensionFlags[o]; exists && f.flag != 0 {
			if f.clear {
				extFlags &= ^f.flag
			} else {
				extFlags |= f.flag
			}
		} else {
			data = append(data, o)
		}
	}
	return flag, pgflag, strings.Join(data, ","), extFlags
}

func SetupSeccomp(config *specs.LinuxSeccomp) (*configs.Seccomp, error) {
	if config == nil {
		return nil, nil
	}

	// No default action specified, no syscalls listed, assume seccomp disabled
	if config.DefaultAction == "" && len(config.Syscalls) == 0 {
		return nil, nil
	}

	// We don't currently support seccomp flags.
	if len(config.Flags) != 0 {
		return nil, errors.New("seccomp flags are not yet supported by runc")
	}

	newConfig := new(configs.Seccomp)
	newConfig.Syscalls = []*configs.Syscall{}

	if len(config.Architectures) > 0 {
		newConfig.Architectures = []string{}
		for _, arch := range config.Architectures {
			newArch, err := seccomp.ConvertStringToArch(string(arch))
			if err != nil {
				return nil, err
			}
			newConfig.Architectures = append(newConfig.Architectures, newArch)
		}
	}

	// Convert default action from string representation
	newDefaultAction, err := seccomp.ConvertStringToAction(string(config.DefaultAction))
	if err != nil {
		return nil, err
	}
	newConfig.DefaultAction = newDefaultAction
	newConfig.DefaultErrnoRet = config.DefaultErrnoRet

	// Loop through all syscall blocks and convert them to libcontainer format
	for _, call := range config.Syscalls {
		newAction, err := seccomp.ConvertStringToAction(string(call.Action))
		if err != nil {
			return nil, err
		}

		for _, name := range call.Names {
			newCall := configs.Syscall{
				Name:     name,
				Action:   newAction,
				ErrnoRet: call.ErrnoRet,
				Args:     []*configs.Arg{},
			}
			// Loop through all the arguments of the syscall and convert them
			for _, arg := range call.Args {
				newOp, err := seccomp.ConvertStringToOperator(string(arg.Op))
				if err != nil {
					return nil, err
				}

				newArg := configs.Arg{
					Index:    arg.Index,
					Value:    arg.Value,
					ValueTwo: arg.ValueTwo,
					Op:       newOp,
				}

				newCall.Args = append(newCall.Args, &newArg)
			}
			newConfig.Syscalls = append(newConfig.Syscalls, &newCall)
		}
	}

	return newConfig, nil
}

func createHooks(rspec *specs.Spec, config *configs.Config) {
	config.Hooks = configs.Hooks{}
	if rspec.Hooks != nil {
		for _, h := range rspec.Hooks.Prestart {
			cmd := createCommandHook(h)
			config.Hooks[configs.Prestart] = append(config.Hooks[configs.Prestart], configs.NewCommandHook(cmd))
		}
		for _, h := range rspec.Hooks.CreateRuntime {
			cmd := createCommandHook(h)
			config.Hooks[configs.CreateRuntime] = append(config.Hooks[configs.CreateRuntime], configs.NewCommandHook(cmd))
		}
		for _, h := range rspec.Hooks.CreateContainer {
			cmd := createCommandHook(h)
			config.Hooks[configs.CreateContainer] = append(config.Hooks[configs.CreateContainer], configs.NewCommandHook(cmd))
		}
		for _, h := range rspec.Hooks.StartContainer {
			cmd := createCommandHook(h)
			config.Hooks[configs.StartContainer] = append(config.Hooks[configs.StartContainer], configs.NewCommandHook(cmd))
		}
		for _, h := range rspec.Hooks.Poststart {
			cmd := createCommandHook(h)
			config.Hooks[configs.Poststart] = append(config.Hooks[configs.Poststart], configs.NewCommandHook(cmd))
		}
		for _, h := range rspec.Hooks.Poststop {
			cmd := createCommandHook(h)
			config.Hooks[configs.Poststop] = append(config.Hooks[configs.Poststop], configs.NewCommandHook(cmd))
		}
	}
}

func createCommandHook(h specs.Hook) configs.Command {
	cmd := configs.Command{
		Path: h.Path,
		Args: h.Args,
		Env:  h.Env,
	}
	if h.Timeout != nil {
		d := time.Duration(*h.Timeout) * time.Second
		cmd.Timeout = &d
	}
	return cmd
}

It looks like the check for `len` here is redundant -- the `for` below will be a no-op when `len == 0`.