daemon: support alternative runtimes MVP
- Closes #43736 
- Closes #42986

Contrary to popular belief, the OCI Runtime specification does not specify the command-line API for runtimes. Looking at containerd's architecture from the lens of the OCI Runtime spec, the _shim_ is the OCI Runtime and runC is "just" an implementation detail of the `io.containerd.runc.v2` runtime. When one configures a non-default runtime in Docker, what they're really doing is instructing Docker to create containers using the `io.containerd.runc.v2` runtime with a configuration option telling the runtime that the runC binary is at some non-default path. Consequently, only OCI runtimes which are compatible with the `io.containerd.runc.v2` shim, such as crun, can be used in this manner. Other OCI runtimes, including kata-containers v2, come with their own containerd shim and are not compatible with `io.containerd.runc.v2`. As Docker has not historically provided a way to select a non-default runtime which requires its own shim, runtimes such as kata-containers v2 could not be used with Docker.

Allow other ContainerD shims to be used with Docker; no daemon configuration required. If the daemon is instructed to create a container with a runtime name which does not match any of the configured or stock runtimes, it passes the name along to ContainerD verbatim. A user can start a container with the kata-containers runtime, for example, simply by calling

    docker run --runtime io.containerd.kata.v2

Runtime names which ContainerD would interpret as a path to an arbitrary binary are disallowed. While handy for development and testing it is not strictly necessary and would allow anyone with Engine API access to trivially execute any binary on the host as root, so we have decided it would be safest for our users if it was not allowed.

It is not yet possible to set an alternative ContainerD shim as the default runtime; it can only be configured per-container. Doing so properly, with validation and configuration reload handling, is quite the nontrivial undertaking with the current state of the daemon configuration logic. That will be addressed in a subsequent PR.

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**- What I did**

**- How I did it**

**- How to verify it**
Unit and integration tests cover the new functionality.

To manually verify:
- Install an alternative runtime with a shim that implements Containerd Runtime v2 on `$PATH`
- `docker run --rm --runtime io.containerd.my-runtime.v1 alpine ls`

The `io.containerd.runc.v2` shim is aliased to `io.containerd.runc-alias.v2` in the development container image as a convenience for manual testing.

**- Description for the changelog**
<!--
Write a short (one line) summary that describes the changes in this
pull request for inclusion in the changelog:
-->

- Alternative OCI runtimes compatible with the [Containerd Runtime v2](https://github.com/containerd/containerd/blob/main/runtime/v2/README.md) API which are installed on the system can now be used to start containers. These runtimes are not listed in `docker info` and cannot be set as the default runtime at this time.

**- A picture of a cute animal (not mandatory but encouraged)**


daemon/daemon_unix.go
//go:build linux || freebsd
// +build linux freebsd

package daemon // import "github.com/docker/docker/daemon"

import (
	"bufio"
	"context"
	"fmt"
	"net"
	"os"
	"path/filepath"
	"runtime"
	"runtime/debug"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/containerd/cgroups"
	statsV1 "github.com/containerd/cgroups/stats/v1"
	statsV2 "github.com/containerd/cgroups/v2/stats"
	"github.com/containerd/containerd/pkg/userns"
	"github.com/docker/docker/api/types"
	"github.com/docker/docker/api/types/blkiodev"
	pblkiodev "github.com/docker/docker/api/types/blkiodev"
	containertypes "github.com/docker/docker/api/types/container"
	"github.com/docker/docker/container"
	"github.com/docker/docker/daemon/config"
	"github.com/docker/docker/daemon/initlayer"
	"github.com/docker/docker/errdefs"
	"github.com/docker/docker/libcontainerd/remote"
	"github.com/docker/docker/libnetwork"
	nwconfig "github.com/docker/docker/libnetwork/config"
	"github.com/docker/docker/libnetwork/drivers/bridge"
	"github.com/docker/docker/libnetwork/netlabel"
	"github.com/docker/docker/libnetwork/netutils"
	"github.com/docker/docker/libnetwork/options"
	lntypes "github.com/docker/docker/libnetwork/types"
	"github.com/docker/docker/opts"
	"github.com/docker/docker/pkg/containerfs"
	"github.com/docker/docker/pkg/idtools"
	"github.com/docker/docker/pkg/parsers"
	"github.com/docker/docker/pkg/parsers/kernel"
	"github.com/docker/docker/pkg/sysinfo"
	"github.com/docker/docker/runconfig"
	volumemounts "github.com/docker/docker/volume/mounts"
	"github.com/moby/sys/mount"
	specs "github.com/opencontainers/runtime-spec/specs-go"
	"github.com/opencontainers/selinux/go-selinux"
	"github.com/opencontainers/selinux/go-selinux/label"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
	"github.com/vishvananda/netlink"
	"golang.org/x/sys/unix"
)

const (
	isWindows = false

	// See https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/tree/kernel/sched/sched.h?id=8cd9234c64c584432f6992fe944ca9e46ca8ea76#n269
	linuxMinCPUShares = 2
	linuxMaxCPUShares = 262144
	platformSupported = true
	// It's not kernel limit, we want this 6M limit to account for overhead during startup, and to supply a reasonable functional container
	linuxMinMemory = 6291456
	// constants for remapped root settings
	defaultIDSpecifier = "default"
	defaultRemappedID  = "dockremap"

	// constant for cgroup drivers
	cgroupFsDriver      = "cgroupfs"
	cgroupSystemdDriver = "systemd"
	cgroupNoneDriver    = "none"
)

type containerGetter interface {
	GetContainer(string) (*container.Container, error)
}

func getMemoryResources(config containertypes.Resources) *specs.LinuxMemory {
	memory := specs.LinuxMemory{}

	if config.Memory > 0 {
		memory.Limit = &config.Memory
	}

	if config.MemoryReservation > 0 {
		memory.Reservation = &config.MemoryReservation
	}

	if config.MemorySwap > 0 {
		memory.Swap = &config.MemorySwap
	}

	if config.MemorySwappiness != nil {
		swappiness := uint64(*config.MemorySwappiness)
		memory.Swappiness = &swappiness
	}

	if config.OomKillDisable != nil {
		memory.DisableOOMKiller = config.OomKillDisable
	}

	if config.KernelMemory != 0 {
		memory.Kernel = &config.KernelMemory
	}

	if config.KernelMemoryTCP != 0 {
		memory.KernelTCP = &config.KernelMemoryTCP
	}

	return &memory
}

func getPidsLimit(config containertypes.Resources) *specs.LinuxPids {
	if config.PidsLimit == nil {
		return nil
	}
	if *config.PidsLimit <= 0 {
		// docker API allows 0 and negative values to unset this to be consistent
		// with default values. When updating values, runc requires -1 to unset
		// the previous limit.
		return &specs.LinuxPids{Limit: -1}
	}
	return &specs.LinuxPids{Limit: *config.PidsLimit}
}

func getCPUResources(config containertypes.Resources) (*specs.LinuxCPU, error) {
	cpu := specs.LinuxCPU{}

	if config.CPUShares < 0 {
		return nil, fmt.Errorf("shares: invalid argument")
	}
	if config.CPUShares >= 0 {
		shares := uint64(config.CPUShares)
		cpu.Shares = &shares
	}

	if config.CpusetCpus != "" {
		cpu.Cpus = config.CpusetCpus
	}

	if config.CpusetMems != "" {
		cpu.Mems = config.CpusetMems
	}

	if config.NanoCPUs > 0 {
		// https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt
		period := uint64(100 * time.Millisecond / time.Microsecond)
		quota := config.NanoCPUs * int64(period) / 1e9
		cpu.Period = &period
		cpu.Quota = &quota
	}

	if config.CPUPeriod != 0 {
		period := uint64(config.CPUPeriod)
		cpu.Period = &period
	}

	if config.CPUQuota != 0 {
		q := config.CPUQuota
		cpu.Quota = &q
	}

	if config.CPURealtimePeriod != 0 {
		period := uint64(config.CPURealtimePeriod)
		cpu.RealtimePeriod = &period
	}

	if config.CPURealtimeRuntime != 0 {
		c := config.CPURealtimeRuntime
		cpu.RealtimeRuntime = &c
	}

	return &cpu, nil
}

func getBlkioWeightDevices(config containertypes.Resources) ([]specs.LinuxWeightDevice, error) {
	var stat unix.Stat_t
	var blkioWeightDevices []specs.LinuxWeightDevice

	for _, weightDevice := range config.BlkioWeightDevice {
		if err := unix.Stat(weightDevice.Path, &stat); err != nil {
			return nil, errors.WithStack(&os.PathError{Op: "stat", Path: weightDevice.Path, Err: err})
		}
		weight := weightDevice.Weight
		d := specs.LinuxWeightDevice{Weight: &weight}
		// The type is 32bit on mips.
		d.Major = int64(unix.Major(uint64(stat.Rdev))) //nolint: unconvert
		d.Minor = int64(unix.Minor(uint64(stat.Rdev))) //nolint: unconvert
		blkioWeightDevices = append(blkioWeightDevices, d)
	}

	return blkioWeightDevices, nil
}

func (daemon *Daemon) parseSecurityOpt(container *container.Container, hostConfig *containertypes.HostConfig) error {
	container.NoNewPrivileges = daemon.configStore.NoNewPrivileges
	return parseSecurityOpt(container, hostConfig)
}

func parseSecurityOpt(container *container.Container, config *containertypes.HostConfig) error {
	var (
		labelOpts []string
		err       error
	)

	for _, opt := range config.SecurityOpt {
		if opt == "no-new-privileges" {
			container.NoNewPrivileges = true
			continue
		}
		if opt == "disable" {
			labelOpts = append(labelOpts, "disable")
			continue
		}

		var con []string
		if strings.Contains(opt, "=") {
			con = strings.SplitN(opt, "=", 2)
		} else if strings.Contains(opt, ":") {
			con = strings.SplitN(opt, ":", 2)
			logrus.Warn("Security options with `:` as a separator are deprecated and will be completely unsupported in 17.04, use `=` instead.")
		}
		if len(con) != 2 {
			return fmt.Errorf("invalid --security-opt 1: %q", opt)
		}

		switch con[0] {
		case "label":
			labelOpts = append(labelOpts, con[1])
		case "apparmor":
			container.AppArmorProfile = con[1]
		case "seccomp":
			container.SeccompProfile = con[1]
		case "no-new-privileges":
			noNewPrivileges, err := strconv.ParseBool(con[1])
			if err != nil {
				return fmt.Errorf("invalid --security-opt 2: %q", opt)
			}
			container.NoNewPrivileges = noNewPrivileges
		default:
			return fmt.Errorf("invalid --security-opt 2: %q", opt)
		}
	}

	container.ProcessLabel, container.MountLabel, err = label.InitLabels(labelOpts)
	return err
}

func getBlkioThrottleDevices(devs []*blkiodev.ThrottleDevice) ([]specs.LinuxThrottleDevice, error) {
	var throttleDevices []specs.LinuxThrottleDevice
	var stat unix.Stat_t

	for _, d := range devs {
		if err := unix.Stat(d.Path, &stat); err != nil {
			return nil, errors.WithStack(&os.PathError{Op: "stat", Path: d.Path, Err: err})
		}
		d := specs.LinuxThrottleDevice{Rate: d.Rate}
		// the type is 32bit on mips
		d.Major = int64(unix.Major(uint64(stat.Rdev))) //nolint: unconvert
		d.Minor = int64(unix.Minor(uint64(stat.Rdev))) //nolint: unconvert
		throttleDevices = append(throttleDevices, d)
	}

	return throttleDevices, nil
}

// adjustParallelLimit takes a number of objects and a proposed limit and
// figures out if it's reasonable (and adjusts it accordingly). This is only
// used for daemon startup, which does a lot of parallel loading of containers
// (and if we exceed RLIMIT_NOFILE then we're in trouble).
func adjustParallelLimit(n int, limit int) int {
	// Rule-of-thumb overhead factor (how many files will each goroutine open
	// simultaneously). Yes, this is ugly but to be frank this whole thing is
	// ugly.
	const overhead = 2

	// On Linux, we need to ensure that parallelStartupJobs doesn't cause us to
	// exceed RLIMIT_NOFILE. If parallelStartupJobs is too large, we reduce it
	// and give a warning (since in theory the user should increase their
	// ulimits to the largest possible value for dockerd).
	var rlim unix.Rlimit
	if err := unix.Getrlimit(unix.RLIMIT_NOFILE, &rlim); err != nil {
		logrus.Warnf("Couldn't find dockerd's RLIMIT_NOFILE to double-check startup parallelism factor: %v", err)
		return limit
	}
	softRlimit := int(rlim.Cur)

	// Much fewer containers than RLIMIT_NOFILE. No need to adjust anything.
	if softRlimit > overhead*n {
		return limit
	}

	// RLIMIT_NOFILE big enough, no need to adjust anything.
	if softRlimit > overhead*limit {
		return limit
	}

	logrus.Warnf("Found dockerd's open file ulimit (%v) is far too small -- consider increasing it significantly (at least %v)", softRlimit, overhead*limit)
	return softRlimit / overhead
}

// adaptContainerSettings is called during container creation to modify any
// settings necessary in the HostConfig structure.
func (daemon *Daemon) adaptContainerSettings(hostConfig *containertypes.HostConfig, adjustCPUShares bool) error {
	if adjustCPUShares && hostConfig.CPUShares > 0 {
		// Handle unsupported CPUShares
		if hostConfig.CPUShares < linuxMinCPUShares {
			logrus.Warnf("Changing requested CPUShares of %d to minimum allowed of %d", hostConfig.CPUShares, linuxMinCPUShares)
			hostConfig.CPUShares = linuxMinCPUShares
		} else if hostConfig.CPUShares > linuxMaxCPUShares {
			logrus.Warnf("Changing requested CPUShares of %d to maximum allowed of %d", hostConfig.CPUShares, linuxMaxCPUShares)
			hostConfig.CPUShares = linuxMaxCPUShares
		}
	}
	if hostConfig.Memory > 0 && hostConfig.MemorySwap == 0 {
		// By default, MemorySwap is set to twice the size of Memory.
		hostConfig.MemorySwap = hostConfig.Memory * 2
	}
	if hostConfig.ShmSize == 0 {
		hostConfig.ShmSize = config.DefaultShmSize
		if daemon.configStore != nil {
			hostConfig.ShmSize = int64(daemon.configStore.ShmSize)
		}
	}
	// Set default IPC mode, if unset for container
	if hostConfig.IpcMode.IsEmpty() {
		m := config.DefaultIpcMode
		if daemon.configStore != nil {
			m = containertypes.IpcMode(daemon.configStore.IpcMode)
		}
		hostConfig.IpcMode = m
	}

	// Set default cgroup namespace mode, if unset for container
	if hostConfig.CgroupnsMode.IsEmpty() {
		// for cgroup v2: unshare cgroupns even for privileged containers
		// https://github.com/containers/libpod/pull/4374#issuecomment-549776387
		if hostConfig.Privileged && cgroups.Mode() != cgroups.Unified {
			hostConfig.CgroupnsMode = containertypes.CgroupnsModeHost
		} else {
			m := containertypes.CgroupnsModeHost
			if cgroups.Mode() == cgroups.Unified {
				m = containertypes.CgroupnsModePrivate
			}
			if daemon.configStore != nil {
				m = containertypes.CgroupnsMode(daemon.configStore.CgroupNamespaceMode)
			}
			hostConfig.CgroupnsMode = m
		}
	}

	adaptSharedNamespaceContainer(daemon, hostConfig)

	var err error
	secOpts, err := daemon.generateSecurityOpt(hostConfig)
	if err != nil {
		return err
	}
	hostConfig.SecurityOpt = append(hostConfig.SecurityOpt, secOpts...)
	if hostConfig.OomKillDisable == nil {
		defaultOomKillDisable := false
		hostConfig.OomKillDisable = &defaultOomKillDisable
	}

	return nil
}

// adaptSharedNamespaceContainer replaces container name with its ID in hostConfig.
// To be more precisely, it modifies `container:name` to `container:ID` of PidMode, IpcMode
// and NetworkMode.
//
// When a container shares its namespace with another container, use ID can keep the namespace
// sharing connection between the two containers even the another container is renamed.
func adaptSharedNamespaceContainer(daemon containerGetter, hostConfig *containertypes.HostConfig) {
	containerPrefix := "container:"
	if hostConfig.PidMode.IsContainer() {
		pidContainer := hostConfig.PidMode.Container()
		// if there is any error returned here, we just ignore it and leave it to be
		// handled in the following logic
		if c, err := daemon.GetContainer(pidContainer); err == nil {
			hostConfig.PidMode = containertypes.PidMode(containerPrefix + c.ID)
		}
	}
	if hostConfig.IpcMode.IsContainer() {
		ipcContainer := hostConfig.IpcMode.Container()
		if c, err := daemon.GetContainer(ipcContainer); err == nil {
			hostConfig.IpcMode = containertypes.IpcMode(containerPrefix + c.ID)
		}
	}
	if hostConfig.NetworkMode.IsContainer() {
		netContainer := hostConfig.NetworkMode.ConnectedContainer()
		if c, err := daemon.GetContainer(netContainer); err == nil {
			hostConfig.NetworkMode = containertypes.NetworkMode(containerPrefix + c.ID)
		}
	}
}

// verifyPlatformContainerResources performs platform-specific validation of the container's resource-configuration
func verifyPlatformContainerResources(resources *containertypes.Resources, sysInfo *sysinfo.SysInfo, update bool) (warnings []string, err error) {
	fixMemorySwappiness(resources)

	// memory subsystem checks and adjustments
	if resources.Memory != 0 && resources.Memory < linuxMinMemory {
		return warnings, fmt.Errorf("Minimum memory limit allowed is 6MB")
	}
	if resources.Memory > 0 && !sysInfo.MemoryLimit {
		warnings = append(warnings, "Your kernel does not support memory limit capabilities or the cgroup is not mounted. Limitation discarded.")
		resources.Memory = 0
		resources.MemorySwap = -1
	}
	if resources.Memory > 0 && resources.MemorySwap != -1 && !sysInfo.SwapLimit {
		warnings = append(warnings, "Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.")
		resources.MemorySwap = -1
	}
	if resources.Memory > 0 && resources.MemorySwap > 0 && resources.MemorySwap < resources.Memory {
		return warnings, fmt.Errorf("Minimum memoryswap limit should be larger than memory limit, see usage")
	}
	if resources.Memory == 0 && resources.MemorySwap > 0 && !update {
		return warnings, fmt.Errorf("You should always set the Memory limit when using Memoryswap limit, see usage")
	}
	if resources.MemorySwappiness != nil && !sysInfo.MemorySwappiness {
		warnings = append(warnings, "Your kernel does not support memory swappiness capabilities or the cgroup is not mounted. Memory swappiness discarded.")
		resources.MemorySwappiness = nil
	}
	if resources.MemorySwappiness != nil {
		swappiness := *resources.MemorySwappiness
		if swappiness < 0 || swappiness > 100 {
			return warnings, fmt.Errorf("Invalid value: %v, valid memory swappiness range is 0-100", swappiness)
		}
	}
	if resources.MemoryReservation > 0 && !sysInfo.MemoryReservation {
		warnings = append(warnings, "Your kernel does not support memory soft limit capabilities or the cgroup is not mounted. Limitation discarded.")
		resources.MemoryReservation = 0
	}
	if resources.MemoryReservation > 0 && resources.MemoryReservation < linuxMinMemory {
		return warnings, fmt.Errorf("Minimum memory reservation allowed is 6MB")
	}
	if resources.Memory > 0 && resources.MemoryReservation > 0 && resources.Memory < resources.MemoryReservation {
		return warnings, fmt.Errorf("Minimum memory limit can not be less than memory reservation limit, see usage")
	}
	if resources.KernelMemory > 0 {
		// Kernel memory limit is not supported on cgroup v2.
		// Even on cgroup v1, kernel memory limit (`kmem.limit_in_bytes`) has been deprecated since kernel 5.4.
		// https://github.com/torvalds/linux/commit/0158115f702b0ba208ab0b5adf44cae99b3ebcc7
		if !sysInfo.KernelMemory {
			warnings = append(warnings, "Your kernel does not support kernel memory limit capabilities or the cgroup is not mounted. Limitation discarded.")
			resources.KernelMemory = 0
		}
		if resources.KernelMemory > 0 && resources.KernelMemory < linuxMinMemory {
			return warnings, fmt.Errorf("Minimum kernel memory limit allowed is 6MB")
		}
		if !kernel.CheckKernelVersion(4, 0, 0) {
			warnings = append(warnings, "You specified a kernel memory limit on a kernel older than 4.0. Kernel memory limits are experimental on older kernels, it won't work as expected and can cause your system to be unstable.")
		}
	}
	if resources.OomKillDisable != nil && !sysInfo.OomKillDisable {
		// only produce warnings if the setting wasn't to *disable* the OOM Kill; no point
		// warning the caller if they already wanted the feature to be off
		if *resources.OomKillDisable {
			warnings = append(warnings, "Your kernel does not support OomKillDisable. OomKillDisable discarded.")
		}
		resources.OomKillDisable = nil
	}
	if resources.OomKillDisable != nil && *resources.OomKillDisable && resources.Memory == 0 {
		warnings = append(warnings, "OOM killer is disabled for the container, but no memory limit is set, this can result in the system running out of resources.")
	}
	if resources.PidsLimit != nil && !sysInfo.PidsLimit {
		if *resources.PidsLimit > 0 {
			warnings = append(warnings, "Your kernel does not support PIDs limit capabilities or the cgroup is not mounted. PIDs limit discarded.")
		}
		resources.PidsLimit = nil
	}

	// cpu subsystem checks and adjustments
	if resources.NanoCPUs > 0 && resources.CPUPeriod > 0 {
		return warnings, fmt.Errorf("Conflicting options: Nano CPUs and CPU Period cannot both be set")
	}
	if resources.NanoCPUs > 0 && resources.CPUQuota > 0 {
		return warnings, fmt.Errorf("Conflicting options: Nano CPUs and CPU Quota cannot both be set")
	}
	if resources.NanoCPUs > 0 && !sysInfo.CPUCfs {
		return warnings, fmt.Errorf("NanoCPUs can not be set, as your kernel does not support CPU CFS scheduler or the cgroup is not mounted")
	}
	// The highest precision we could get on Linux is 0.001, by setting
	//   cpu.cfs_period_us=1000ms
	//   cpu.cfs_quota=1ms
	// See the following link for details:
	// https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt
	// Here we don't set the lower limit and it is up to the underlying platform (e.g., Linux) to return an error.
	// The error message is 0.01 so that this is consistent with Windows
	if resources.NanoCPUs < 0 || resources.NanoCPUs > int64(sysinfo.NumCPU())*1e9 {
		return warnings, fmt.Errorf("Range of CPUs is from 0.01 to %d.00, as there are only %d CPUs available", sysinfo.NumCPU(), sysinfo.NumCPU())
	}

	if resources.CPUShares > 0 && !sysInfo.CPUShares {
		warnings = append(warnings, "Your kernel does not support CPU shares or the cgroup is not mounted. Shares discarded.")
		resources.CPUShares = 0
	}
	if (resources.CPUPeriod != 0 || resources.CPUQuota != 0) && !sysInfo.CPUCfs {
		warnings = append(warnings, "Your kernel does not support CPU CFS scheduler. CPU period/quota discarded.")
		resources.CPUPeriod = 0
		resources.CPUQuota = 0
	}
	if resources.CPUPeriod != 0 && (resources.CPUPeriod < 1000 || resources.CPUPeriod > 1000000) {
		return warnings, fmt.Errorf("CPU cfs period can not be less than 1ms (i.e. 1000) or larger than 1s (i.e. 1000000)")
	}
	if resources.CPUQuota > 0 && resources.CPUQuota < 1000 {
		return warnings, fmt.Errorf("CPU cfs quota can not be less than 1ms (i.e. 1000)")
	}
	if resources.CPUPercent > 0 {
		warnings = append(warnings, fmt.Sprintf("%s does not support CPU percent. Percent discarded.", runtime.GOOS))
		resources.CPUPercent = 0
	}

	// cpuset subsystem checks and adjustments
	if (resources.CpusetCpus != "" || resources.CpusetMems != "") && !sysInfo.Cpuset {
		warnings = append(warnings, "Your kernel does not support cpuset or the cgroup is not mounted. Cpuset discarded.")
		resources.CpusetCpus = ""
		resources.CpusetMems = ""
	}
	cpusAvailable, err := sysInfo.IsCpusetCpusAvailable(resources.CpusetCpus)
	if err != nil {
		return warnings, errors.Wrapf(err, "Invalid value %s for cpuset cpus", resources.CpusetCpus)
	}
	if !cpusAvailable {
		return warnings, fmt.Errorf("Requested CPUs are not available - requested %s, available: %s", resources.CpusetCpus, sysInfo.Cpus)
	}
	memsAvailable, err := sysInfo.IsCpusetMemsAvailable(resources.CpusetMems)
	if err != nil {
		return warnings, errors.Wrapf(err, "Invalid value %s for cpuset mems", resources.CpusetMems)
	}
	if !memsAvailable {
		return warnings, fmt.Errorf("Requested memory nodes are not available - requested %s, available: %s", resources.CpusetMems, sysInfo.Mems)
	}

	// blkio subsystem checks and adjustments
	if resources.BlkioWeight > 0 && !sysInfo.BlkioWeight {
		warnings = append(warnings, "Your kernel does not support Block I/O weight or the cgroup is not mounted. Weight discarded.")
		resources.BlkioWeight = 0
	}
	if resources.BlkioWeight > 0 && (resources.BlkioWeight < 10 || resources.BlkioWeight > 1000) {
		return warnings, fmt.Errorf("Range of blkio weight is from 10 to 1000")
	}
	if resources.IOMaximumBandwidth != 0 || resources.IOMaximumIOps != 0 {
		return warnings, fmt.Errorf("Invalid QoS settings: %s does not support Maximum IO Bandwidth or Maximum IO IOps", runtime.GOOS)
	}
	if len(resources.BlkioWeightDevice) > 0 && !sysInfo.BlkioWeightDevice {
		warnings = append(warnings, "Your kernel does not support Block I/O weight_device or the cgroup is not mounted. Weight-device discarded.")
		resources.BlkioWeightDevice = []*pblkiodev.WeightDevice{}
	}
	if len(resources.BlkioDeviceReadBps) > 0 && !sysInfo.BlkioReadBpsDevice {
		warnings = append(warnings, "Your kernel does not support BPS Block I/O read limit or the cgroup is not mounted. Block I/O BPS read limit discarded.")
		resources.BlkioDeviceReadBps = []*pblkiodev.ThrottleDevice{}
	}
	if len(resources.BlkioDeviceWriteBps) > 0 && !sysInfo.BlkioWriteBpsDevice {
		warnings = append(warnings, "Your kernel does not support BPS Block I/O write limit or the cgroup is not mounted. Block I/O BPS write limit discarded.")
		resources.BlkioDeviceWriteBps = []*pblkiodev.ThrottleDevice{}

	}
	if len(resources.BlkioDeviceReadIOps) > 0 && !sysInfo.BlkioReadIOpsDevice {
		warnings = append(warnings, "Your kernel does not support IOPS Block read limit or the cgroup is not mounted. Block I/O IOPS read limit discarded.")
		resources.BlkioDeviceReadIOps = []*pblkiodev.ThrottleDevice{}
	}
	if len(resources.BlkioDeviceWriteIOps) > 0 && !sysInfo.BlkioWriteIOpsDevice {
		warnings = append(warnings, "Your kernel does not support IOPS Block write limit or the cgroup is not mounted. Block I/O IOPS write limit discarded.")
		resources.BlkioDeviceWriteIOps = []*pblkiodev.ThrottleDevice{}
	}

	return warnings, nil
}

func (daemon *Daemon) getCgroupDriver() string {
	if UsingSystemd(daemon.configStore) {
		return cgroupSystemdDriver
	}
	if daemon.Rootless() {
		return cgroupNoneDriver
	}
	return cgroupFsDriver
}

// getCD gets the raw value of the native.cgroupdriver option, if set.
func getCD(config *config.Config) string {
	for _, option := range config.ExecOptions {
		key, val, err := parsers.ParseKeyValueOpt(option)
		if err != nil || !strings.EqualFold(key, "native.cgroupdriver") {
			continue
		}
		return val
	}
	return ""
}

// verifyCgroupDriver validates native.cgroupdriver
func verifyCgroupDriver(config *config.Config) error {
	cd := getCD(config)
	if cd == "" || cd == cgroupFsDriver || cd == cgroupSystemdDriver {
		return nil
	}
	if cd == cgroupNoneDriver {
		return fmt.Errorf("native.cgroupdriver option %s is internally used and cannot be specified manually", cd)
	}
	return fmt.Errorf("native.cgroupdriver option %s not supported", cd)
}

// UsingSystemd returns true if cli option includes native.cgroupdriver=systemd
func UsingSystemd(config *config.Config) bool {
	cd := getCD(config)

	if cd == cgroupSystemdDriver {
		return true
	}
	// On cgroup v2 hosts, default to systemd driver
	if cd == "" && cgroups.Mode() == cgroups.Unified && isRunningSystemd() {
		return true
	}
	return false
}

var (
	runningSystemd bool
	detectSystemd  sync.Once
)

// isRunningSystemd checks whether the host was booted with systemd as its init
// system. This functions similarly to systemd's `sd_booted(3)`: internally, it
// checks whether /run/systemd/system/ exists and is a directory.
// http://www.freedesktop.org/software/systemd/man/sd_booted.html
//
// NOTE: This function comes from package github.com/coreos/go-systemd/util
// It was borrowed here to avoid a dependency on cgo.
func isRunningSystemd() bool {
	detectSystemd.Do(func() {
		fi, err := os.Lstat("/run/systemd/system")
		if err != nil {
			return
		}
		runningSystemd = fi.IsDir()
	})
	return runningSystemd
}

// verifyPlatformContainerSettings performs platform-specific validation of the
// hostconfig and config structures.
func verifyPlatformContainerSettings(daemon *Daemon, hostConfig *containertypes.HostConfig, update bool) (warnings []string, err error) {
	if hostConfig == nil {
		return nil, nil
	}
	sysInfo := daemon.RawSysInfo()

	w, err := verifyPlatformContainerResources(&hostConfig.Resources, sysInfo, update)

	// no matter err is nil or not, w could have data in itself.
	warnings = append(warnings, w...)

	if err != nil {
		return warnings, err
	}

	if !hostConfig.IpcMode.Valid() {
		return warnings, errors.Errorf("invalid IPC mode: %v", hostConfig.IpcMode)
	}
	if !hostConfig.PidMode.Valid() {
		return warnings, errors.Errorf("invalid PID mode: %v", hostConfig.PidMode)
	}
	if hostConfig.ShmSize < 0 {
		return warnings, fmt.Errorf("SHM size can not be less than 0")
	}
	if !hostConfig.UTSMode.Valid() {
		return warnings, errors.Errorf("invalid UTS mode: %v", hostConfig.UTSMode)
	}

	if hostConfig.OomScoreAdj < -1000 || hostConfig.OomScoreAdj > 1000 {
		return warnings, fmt.Errorf("Invalid value %d, range for oom score adj is [-1000, 1000]", hostConfig.OomScoreAdj)
	}

	// ip-forwarding does not affect container with '--net=host' (or '--net=none')
	if sysInfo.IPv4ForwardingDisabled && !(hostConfig.NetworkMode.IsHost() || hostConfig.NetworkMode.IsNone()) {
		warnings = append(warnings, "IPv4 forwarding is disabled. Networking will not work.")
	}
	if hostConfig.NetworkMode.IsHost() && len(hostConfig.PortBindings) > 0 {
		warnings = append(warnings, "Published ports are discarded when using host network mode")
	}

	// check for various conflicting options with user namespaces
	if daemon.configStore.RemappedRoot != "" && hostConfig.UsernsMode.IsPrivate() {
		if hostConfig.Privileged {
			return warnings, fmt.Errorf("privileged mode is incompatible with user namespaces.  You must run the container in the host namespace when running privileged mode")
		}
		if hostConfig.NetworkMode.IsHost() && !hostConfig.UsernsMode.IsHost() {
			return warnings, fmt.Errorf("cannot share the host's network namespace when user namespaces are enabled")
		}
		if hostConfig.PidMode.IsHost() && !hostConfig.UsernsMode.IsHost() {
			return warnings, fmt.Errorf("cannot share the host PID namespace when user namespaces are enabled")
		}
	}
	if hostConfig.CgroupParent != "" && UsingSystemd(daemon.configStore) {
		// CgroupParent for systemd cgroup should be named as "xxx.slice"
		if len(hostConfig.CgroupParent) <= 6 || !strings.HasSuffix(hostConfig.CgroupParent, ".slice") {
			return warnings, fmt.Errorf("cgroup-parent for systemd cgroup should be a valid slice named as \"xxx.slice\"")
		}
	}
	if hostConfig.Runtime == "" {
		hostConfig.Runtime = daemon.configStore.GetDefaultRuntimeName()
	}

	if rt := daemon.configStore.GetRuntime(hostConfig.Runtime); rt == nil {
		return warnings, fmt.Errorf("Unknown runtime specified %s", hostConfig.Runtime)
	}

	parser := volumemounts.NewParser()
	for dest := range hostConfig.Tmpfs {
		if err := parser.ValidateTmpfsMountDestination(dest); err != nil {
			return warnings, err
		}
	}

	if !hostConfig.CgroupnsMode.Valid() {
		return warnings, fmt.Errorf("invalid cgroup namespace mode: %v", hostConfig.CgroupnsMode)
	}
	if hostConfig.CgroupnsMode.IsPrivate() {
		if !sysInfo.CgroupNamespaces {
			warnings = append(warnings, "Your kernel does not support cgroup namespaces.  Cgroup namespace setting discarded.")
		}
	}

	return warnings, nil
}

// verifyDaemonSettings performs validation of daemon config struct
func verifyDaemonSettings(conf *config.Config) error {
	if conf.ContainerdNamespace == conf.ContainerdPluginNamespace {
		return errors.New("containers namespace and plugins namespace cannot be the same")
	}
	// Check for mutually incompatible config options
	if conf.BridgeConfig.Iface != "" && conf.BridgeConfig.IP != "" {
		return fmt.Errorf("You specified -b & --bip, mutually exclusive options. Please specify only one")
	}
	if !conf.BridgeConfig.EnableIPTables && !conf.BridgeConfig.InterContainerCommunication {
		return fmt.Errorf("You specified --iptables=false with --icc=false. ICC=false uses iptables to function. Please set --icc or --iptables to true")
	}
	if conf.BridgeConfig.EnableIP6Tables && !conf.Experimental {
		return fmt.Errorf("ip6tables rules are only available if experimental features are enabled")
	}
	if !conf.BridgeConfig.EnableIPTables && conf.BridgeConfig.EnableIPMasq {
		conf.BridgeConfig.EnableIPMasq = false
	}
	if err := verifyCgroupDriver(conf); err != nil {
		return err
	}
	if conf.CgroupParent != "" && UsingSystemd(conf) {
		if len(conf.CgroupParent) <= 6 || !strings.HasSuffix(conf.CgroupParent, ".slice") {
			return fmt.Errorf("cgroup-parent for systemd cgroup should be a valid slice named as \"xxx.slice\"")
		}
	}

	if conf.Rootless && UsingSystemd(conf) && cgroups.Mode() != cgroups.Unified {
		return fmt.Errorf("exec-opt native.cgroupdriver=systemd requires cgroup v2 for rootless mode")
	}

	configureRuntimes(conf)
	if rtName := conf.GetDefaultRuntimeName(); rtName != "" {
		if conf.GetRuntime(rtName) == nil {
			return fmt.Errorf("specified default runtime '%s' does not exist", rtName)
		}
	}
	return nil
}

// checkSystem validates platform-specific requirements
func checkSystem() error {
	return nil
}

// configureMaxThreads sets the Go runtime max threads threshold
// which is 90% of the kernel setting from /proc/sys/kernel/threads-max
func configureMaxThreads(config *config.Config) error {
	mt, err := os.ReadFile("/proc/sys/kernel/threads-max")
	if err != nil {
		return err
	}
	mtint, err := strconv.Atoi(strings.TrimSpace(string(mt)))
	if err != nil {
		return err
	}
	maxThreads := (mtint / 100) * 90
	debug.SetMaxThreads(maxThreads)
	logrus.Debugf("Golang's threads limit set to %d", maxThreads)
	return nil
}

func overlaySupportsSelinux() (bool, error) {
	f, err := os.Open("/proc/kallsyms")
	if err != nil {
		if os.IsNotExist(err) {
			return false, nil
		}
		return false, err
	}
	defer f.Close()

	s := bufio.NewScanner(f)
	for s.Scan() {
		if strings.HasSuffix(s.Text(), " security_inode_copy_up") {
			return true, nil
		}
	}

	return false, s.Err()
}

// configureKernelSecuritySupport configures and validates security support for the kernel
func configureKernelSecuritySupport(config *config.Config, driverName string) error {
	if config.EnableSelinuxSupport {
		if !selinux.GetEnabled() {
			logrus.Warn("Docker could not enable SELinux on the host system")
			return nil
		}

		if driverName == "overlay" || driverName == "overlay2" {
			// If driver is overlay or overlay2, make sure kernel
			// supports selinux with overlay.
			supported, err := overlaySupportsSelinux()
			if err != nil {
				return err
			}

			if !supported {
				logrus.Warnf("SELinux is not supported with the %v graph driver on this kernel", driverName)
			}
		}
	} else {
		selinux.SetDisabled()
	}
	return nil
}

// initNetworkController initializes the libnetwork controller and configures
// network settings. If there's active sandboxes, configuration changes will not
// take effect.
func (daemon *Daemon) initNetworkController(activeSandboxes map[string]interface{}) error {
	netOptions, err := daemon.networkOptions(daemon.PluginStore, activeSandboxes)
	if err != nil {
		return err
	}

	daemon.netController, err = libnetwork.New(netOptions...)
	if err != nil {
		return fmt.Errorf("error obtaining controller instance: %v", err)
	}

	if len(activeSandboxes) > 0 {
		logrus.Info("there are running containers, updated network configuration will not take affect")
	} else if err := configureNetworking(daemon.netController, daemon.configStore); err != nil {
		return err
	}

	// Set HostGatewayIP to the default bridge's IP if it is empty
	setHostGatewayIP(daemon.netController, daemon.configStore)
	return nil
}

func configureNetworking(controller libnetwork.NetworkController, conf *config.Config) error {
	// Initialize default network on "null"
	if n, _ := controller.NetworkByName("none"); n == nil {
		if _, err := controller.NewNetwork("null", "none", "", libnetwork.NetworkOptionPersist(true)); err != nil {
			return errors.Wrap(err, `error creating default "null" network`)
		}
	}

	// Initialize default network on "host"
	if n, _ := controller.NetworkByName("host"); n == nil {
		if _, err := controller.NewNetwork("host", "host", "", libnetwork.NetworkOptionPersist(true)); err != nil {
			return errors.Wrap(err, `error creating default "host" network`)
		}
	}

	// Clear stale bridge network
	if n, err := controller.NetworkByName("bridge"); err == nil {
		if err = n.Delete(); err != nil {
			return errors.Wrap(err, `could not delete the default "bridge"" network`)
		}
		if len(conf.NetworkConfig.DefaultAddressPools.Value()) > 0 && !conf.LiveRestoreEnabled {
			removeDefaultBridgeInterface()
		}
	}

	if !conf.DisableBridge {
		// Initialize default driver "bridge"
		if err := initBridgeDriver(controller, conf); err != nil {
			return err
		}
	} else {
		removeDefaultBridgeInterface()
	}

	return nil
}

// setHostGatewayIP sets cfg.HostGatewayIP to the default bridge's IP if it is empty.
func setHostGatewayIP(controller libnetwork.NetworkController, config *config.Config) {
	if config.HostGatewayIP != nil {
		return
	}
	if n, err := controller.NetworkByName("bridge"); err == nil {
		v4Info, v6Info := n.Info().IpamInfo()
		var gateway net.IP
		if len(v4Info) > 0 {
			gateway = v4Info[0].Gateway.IP
		} else if len(v6Info) > 0 {
			gateway = v6Info[0].Gateway.IP
		}
		config.HostGatewayIP = gateway
	}
}

func driverOptions(config *config.Config) nwconfig.Option {
	return nwconfig.OptionDriverConfig("bridge", options.Generic{
		netlabel.GenericData: options.Generic{
			"EnableIPForwarding":  config.BridgeConfig.EnableIPForward,
			"EnableIPTables":      config.BridgeConfig.EnableIPTables,
			"EnableIP6Tables":     config.BridgeConfig.EnableIP6Tables,
			"EnableUserlandProxy": config.BridgeConfig.EnableUserlandProxy,
			"UserlandProxyPath":   config.BridgeConfig.UserlandProxyPath,
		},
	})
}

func initBridgeDriver(controller libnetwork.NetworkController, config *config.Config) error {
	bridgeName := bridge.DefaultBridgeName
	if config.BridgeConfig.Iface != "" {
		bridgeName = config.BridgeConfig.Iface
	}
	netOption := map[string]string{
		bridge.BridgeName:         bridgeName,
		bridge.DefaultBridge:      strconv.FormatBool(true),
		netlabel.DriverMTU:        strconv.Itoa(config.Mtu),
		bridge.EnableIPMasquerade: strconv.FormatBool(config.BridgeConfig.EnableIPMasq),
		bridge.EnableICC:          strconv.FormatBool(config.BridgeConfig.InterContainerCommunication),
	}

	// --ip processing
	if config.BridgeConfig.DefaultIP != nil {
		netOption[bridge.DefaultBindingIP] = config.BridgeConfig.DefaultIP.String()
	}

	ipamV4Conf := &libnetwork.IpamConf{AuxAddresses: make(map[string]string)}

	nwList, nw6List, err := netutils.ElectInterfaceAddresses(bridgeName)
	if err != nil {
		return errors.Wrap(err, "list bridge addresses failed")
	}

	nw := nwList[0]
	if len(nwList) > 1 && config.BridgeConfig.FixedCIDR != "" {
		_, fCIDR, err := net.ParseCIDR(config.BridgeConfig.FixedCIDR)
		if err != nil {
			return errors.Wrap(err, "parse CIDR failed")
		}
		// Iterate through in case there are multiple addresses for the bridge
		for _, entry := range nwList {
			if fCIDR.Contains(entry.IP) {
				nw = entry
				break
			}
		}
	}

	ipamV4Conf.PreferredPool = lntypes.GetIPNetCanonical(nw).String()
	hip, _ := lntypes.GetHostPartIP(nw.IP, nw.Mask)
	if hip.IsGlobalUnicast() {
		ipamV4Conf.Gateway = nw.IP.String()
	}

	if config.BridgeConfig.IP != "" {
		ip, ipNet, err := net.ParseCIDR(config.BridgeConfig.IP)
		if err != nil {
			return err
		}
		ipamV4Conf.PreferredPool = ipNet.String()
		ipamV4Conf.Gateway = ip.String()
	} else if bridgeName == bridge.DefaultBridgeName && ipamV4Conf.PreferredPool != "" {
		logrus.Infof("Default bridge (%s) is assigned with an IP address %s. Daemon option --bip can be used to set a preferred IP address", bridgeName, ipamV4Conf.PreferredPool)
	}

	if config.BridgeConfig.FixedCIDR != "" {
		_, fCIDR, err := net.ParseCIDR(config.BridgeConfig.FixedCIDR)
		if err != nil {
			return err
		}

		ipamV4Conf.SubPool = fCIDR.String()
	}

	if config.BridgeConfig.DefaultGatewayIPv4 != nil {
		ipamV4Conf.AuxAddresses["DefaultGatewayIPv4"] = config.BridgeConfig.DefaultGatewayIPv4.String()
	}

	var (
		deferIPv6Alloc bool
		ipamV6Conf     *libnetwork.IpamConf
	)

	if config.BridgeConfig.EnableIPv6 && config.BridgeConfig.FixedCIDRv6 == "" {
		return errdefs.InvalidParameter(errors.New("IPv6 is enabled for the default bridge, but no subnet is configured. Specify an IPv6 subnet using --fixed-cidr-v6"))
	} else if config.BridgeConfig.FixedCIDRv6 != "" {
		_, fCIDRv6, err := net.ParseCIDR(config.BridgeConfig.FixedCIDRv6)
		if err != nil {
			return err
		}

		// In case user has specified the daemon flag --fixed-cidr-v6 and the passed network has
		// at least 48 host bits, we need to guarantee the current behavior where the containers'
		// IPv6 addresses will be constructed based on the containers' interface MAC address.
		// We do so by telling libnetwork to defer the IPv6 address allocation for the endpoints
		// on this network until after the driver has created the endpoint and returned the
		// constructed address. Libnetwork will then reserve this address with the ipam driver.
		ones, _ := fCIDRv6.Mask.Size()
		deferIPv6Alloc = ones <= 80

		ipamV6Conf = &libnetwork.IpamConf{
			AuxAddresses:  make(map[string]string),
			PreferredPool: fCIDRv6.String(),
		}

		// In case the --fixed-cidr-v6 is specified and the current docker0 bridge IPv6
		// address belongs to the same network, we need to inform libnetwork about it, so
		// that it can be reserved with IPAM and it will not be given away to somebody else
		for _, nw6 := range nw6List {
			if fCIDRv6.Contains(nw6.IP) {
				ipamV6Conf.Gateway = nw6.IP.String()
				break
			}
		}
	}

	if config.BridgeConfig.DefaultGatewayIPv6 != nil {
		if ipamV6Conf == nil {
			ipamV6Conf = &libnetwork.IpamConf{AuxAddresses: make(map[string]string)}
		}
		ipamV6Conf.AuxAddresses["DefaultGatewayIPv6"] = config.BridgeConfig.DefaultGatewayIPv6.String()
	}

	v4Conf := []*libnetwork.IpamConf{ipamV4Conf}
	v6Conf := []*libnetwork.IpamConf{}
	if ipamV6Conf != nil {
		v6Conf = append(v6Conf, ipamV6Conf)
	}
	// Initialize default network on "bridge" with the same name
	_, err = controller.NewNetwork("bridge", "bridge", "",
		libnetwork.NetworkOptionEnableIPv6(config.BridgeConfig.EnableIPv6),
		libnetwork.NetworkOptionDriverOpts(netOption),
		libnetwork.NetworkOptionIpam("default", "", v4Conf, v6Conf, nil),
		libnetwork.NetworkOptionDeferIPv6Alloc(deferIPv6Alloc))
	if err != nil {
		return fmt.Errorf("Error creating default \"bridge\" network: %v", err)
	}
	return nil
}

// Remove default bridge interface if present (--bridge=none use case)
func removeDefaultBridgeInterface() {
	if lnk, err := netlink.LinkByName(bridge.DefaultBridgeName); err == nil {
		if err := netlink.LinkDel(lnk); err != nil {
			logrus.Warnf("Failed to remove bridge interface (%s): %v", bridge.DefaultBridgeName, err)
		}
	}
}

func setupInitLayer(idMapping idtools.IdentityMapping) func(containerfs.ContainerFS) error {
	return func(initPath containerfs.ContainerFS) error {
		return initlayer.Setup(initPath, idMapping.RootPair())
	}
}

// Parse the remapped root (user namespace) option, which can be one of:
//
// - username            - valid username from /etc/passwd
// - username:groupname  - valid username; valid groupname from /etc/group
// - uid                 - 32-bit unsigned int valid Linux UID value
// - uid:gid             - uid value; 32-bit unsigned int Linux GID value
//
// If no groupname is specified, and a username is specified, an attempt
// will be made to lookup a gid for that username as a groupname
//
// If names are used, they are verified to exist in passwd/group
func parseRemappedRoot(usergrp string) (string, string, error) {

	var (
		userID, groupID     int
		username, groupname string
	)

	idparts := strings.Split(usergrp, ":")
	if len(idparts) > 2 {
		return "", "", fmt.Errorf("Invalid user/group specification in --userns-remap: %q", usergrp)
	}

	if uid, err := strconv.ParseInt(idparts[0], 10, 32); err == nil {
		// must be a uid; take it as valid
		userID = int(uid)
		luser, err := idtools.LookupUID(userID)
		if err != nil {
			return "", "", fmt.Errorf("Uid %d has no entry in /etc/passwd: %v", userID, err)
		}
		username = luser.Name
		if len(idparts) == 1 {
			// if the uid was numeric and no gid was specified, take the uid as the gid
			groupID = userID
			lgrp, err := idtools.LookupGID(groupID)
			if err != nil {
				return "", "", fmt.Errorf("Gid %d has no entry in /etc/group: %v", groupID, err)
			}
			groupname = lgrp.Name
		}
	} else {
		lookupName := idparts[0]
		// special case: if the user specified "default", they want Docker to create or
		// use (after creation) the "dockremap" user/group for root remapping
		if lookupName == defaultIDSpecifier {
			lookupName = defaultRemappedID
		}
		luser, err := idtools.LookupUser(lookupName)
		if err != nil && idparts[0] != defaultIDSpecifier {
			// error if the name requested isn't the special "dockremap" ID
			return "", "", fmt.Errorf("Error during uid lookup for %q: %v", lookupName, err)
		} else if err != nil {
			// special case-- if the username == "default", then we have been asked
			// to create a new entry pair in /etc/{passwd,group} for which the /etc/sub{uid,gid}
			// ranges will be used for the user and group mappings in user namespaced containers
			_, _, err := idtools.AddNamespaceRangesUser(defaultRemappedID)
			if err == nil {
				return defaultRemappedID, defaultRemappedID, nil
			}
			return "", "", fmt.Errorf("Error during %q user creation: %v", defaultRemappedID, err)
		}
		username = luser.Name
		if len(idparts) == 1 {
			// we only have a string username, and no group specified; look up gid from username as group
			group, err := idtools.LookupGroup(lookupName)
			if err != nil {
				return "", "", fmt.Errorf("Error during gid lookup for %q: %v", lookupName, err)
			}
			groupname = group.Name
		}
	}

	if len(idparts) == 2 {
		// groupname or gid is separately specified and must be resolved
		// to an unsigned 32-bit gid
		if gid, err := strconv.ParseInt(idparts[1], 10, 32); err == nil {
			// must be a gid, take it as valid
			groupID = int(gid)
			lgrp, err := idtools.LookupGID(groupID)
			if err != nil {
				return "", "", fmt.Errorf("Gid %d has no entry in /etc/passwd: %v", groupID, err)
			}
			groupname = lgrp.Name
		} else {
			// not a number; attempt a lookup
			if _, err := idtools.LookupGroup(idparts[1]); err != nil {
				return "", "", fmt.Errorf("Error during groupname lookup for %q: %v", idparts[1], err)
			}
			groupname = idparts[1]
		}
	}
	return username, groupname, nil
}

func setupRemappedRoot(config *config.Config) (idtools.IdentityMapping, error) {
	if runtime.GOOS != "linux" && config.RemappedRoot != "" {
		return idtools.IdentityMapping{}, fmt.Errorf("User namespaces are only supported on Linux")
	}

	// if the daemon was started with remapped root option, parse
	// the config option to the int uid,gid values
	if config.RemappedRoot != "" {
		username, groupname, err := parseRemappedRoot(config.RemappedRoot)
		if err != nil {
			return idtools.IdentityMapping{}, err
		}
		if username == "root" {
			// Cannot setup user namespaces with a 1-to-1 mapping; "--root=0:0" is a no-op
			// effectively
			logrus.Warn("User namespaces: root cannot be remapped with itself; user namespaces are OFF")
			return idtools.IdentityMapping{}, nil
		}
		logrus.Infof("User namespaces: ID ranges will be mapped to subuid/subgid ranges of: %s", username)
		// update remapped root setting now that we have resolved them to actual names
		config.RemappedRoot = fmt.Sprintf("%s:%s", username, groupname)

		mappings, err := idtools.LoadIdentityMapping(username)
		if err != nil {
			return idtools.IdentityMapping{}, errors.Wrap(err, "Can't create ID mappings")
		}
		return mappings, nil
	}
	return idtools.IdentityMapping{}, nil
}

func setupDaemonRoot(config *config.Config, rootDir string, remappedRoot idtools.Identity) error {
	config.Root = rootDir
	// the docker root metadata directory needs to have execute permissions for all users (g+x,o+x)
	// so that syscalls executing as non-root, operating on subdirectories of the graph root
	// (e.g. mounted layers of a container) can traverse this path.
	// The user namespace support will create subdirectories for the remapped root host uid:gid
	// pair owned by that same uid:gid pair for proper write access to those needed metadata and
	// layer content subtrees.
	if _, err := os.Stat(rootDir); err == nil {
		// root current exists; verify the access bits are correct by setting them
		if err = os.Chmod(rootDir, 0711); err != nil {
			return err
		}
	} else if os.IsNotExist(err) {
		// no root exists yet, create it 0711 with root:root ownership
		if err := os.MkdirAll(rootDir, 0711); err != nil {
			return err
		}
	}

	id := idtools.Identity{UID: idtools.CurrentIdentity().UID, GID: remappedRoot.GID}
	// First make sure the current root dir has the correct perms.
	if err := idtools.MkdirAllAndChown(config.Root, 0710, id); err != nil {
		return errors.Wrapf(err, "could not create or set daemon root permissions: %s", config.Root)
	}

	// if user namespaces are enabled we will create a subtree underneath the specified root
	// with any/all specified remapped root uid/gid options on the daemon creating
	// a new subdirectory with ownership set to the remapped uid/gid (so as to allow
	// `chdir()` to work for containers namespaced to that uid/gid)
	if config.RemappedRoot != "" {
		config.Root = filepath.Join(rootDir, fmt.Sprintf("%d.%d", remappedRoot.UID, remappedRoot.GID))
		logrus.Debugf("Creating user namespaced daemon root: %s", config.Root)
		// Create the root directory if it doesn't exist
		if err := idtools.MkdirAllAndChown(config.Root, 0710, id); err != nil {
			return fmt.Errorf("Cannot create daemon root: %s: %v", config.Root, err)
		}
		// we also need to verify that any pre-existing directories in the path to
		// the graphroot won't block access to remapped root--if any pre-existing directory
		// has strict permissions that don't allow "x", container start will fail, so
		// better to warn and fail now
		dirPath := config.Root
		for {
			dirPath = filepath.Dir(dirPath)
			if dirPath == "/" {
				break
			}
			if !idtools.CanAccess(dirPath, remappedRoot) {
				return fmt.Errorf("a subdirectory in your graphroot path (%s) restricts access to the remapped root uid/gid; please fix by allowing 'o+x' permissions on existing directories", config.Root)
			}
		}
	}

	if err := setupDaemonRootPropagation(config); err != nil {
		logrus.WithError(err).WithField("dir", config.Root).Warn("Error while setting daemon root propagation, this is not generally critical but may cause some functionality to not work or fallback to less desirable behavior")
	}
	return nil
}

func setupDaemonRootPropagation(cfg *config.Config) error {
	rootParentMount, mountOptions, err := getSourceMount(cfg.Root)
	if err != nil {
		return errors.Wrap(err, "error getting daemon root's parent mount")
	}

	var cleanupOldFile bool
	cleanupFile := getUnmountOnShutdownPath(cfg)
	defer func() {
		if !cleanupOldFile {
			return
		}
		if err := os.Remove(cleanupFile); err != nil && !os.IsNotExist(err) {
			logrus.WithError(err).WithField("file", cleanupFile).Warn("could not clean up old root propagation unmount file")
		}
	}()

	if hasMountInfoOption(mountOptions, sharedPropagationOption, slavePropagationOption) {
		cleanupOldFile = true
		return nil
	}

	if err := mount.MakeShared(cfg.Root); err != nil {
		return errors.Wrap(err, "could not setup daemon root propagation to shared")
	}

	// check the case where this may have already been a mount to itself.
	// If so then the daemon only performed a remount and should not try to unmount this later.
	if rootParentMount == cfg.Root {
		cleanupOldFile = true
		return nil
	}

	if err := os.MkdirAll(filepath.Dir(cleanupFile), 0700); err != nil {
		return errors.Wrap(err, "error creating dir to store mount cleanup file")
	}

	if err := os.WriteFile(cleanupFile, nil, 0600); err != nil {
		return errors.Wrap(err, "error writing file to signal mount cleanup on shutdown")
	}
	return nil
}

// getUnmountOnShutdownPath generates the path to used when writing the file that signals to the daemon that on shutdown
// the daemon root should be unmounted.
func getUnmountOnShutdownPath(config *config.Config) string {
	return filepath.Join(config.ExecRoot, "unmount-on-shutdown")
}

// registerLinks writes the links to a file.
func (daemon *Daemon) registerLinks(container *container.Container, hostConfig *containertypes.HostConfig) error {
	if hostConfig == nil || hostConfig.NetworkMode.IsUserDefined() {
		return nil
	}

	for _, l := range hostConfig.Links {
		name, alias, err := opts.ParseLink(l)
		if err != nil {
			return err
		}
		child, err := daemon.GetContainer(name)
		if err != nil {
			if errdefs.IsNotFound(err) {
				// Trying to link to a non-existing container is not valid, and
				// should return an "invalid parameter" error. Returning a "not
				// found" error here would make the client report the container's
				// image could not be found (see moby/moby#39823)
				err = errdefs.InvalidParameter(err)
			}
			return errors.Wrapf(err, "could not get container for %s", name)
		}
		for child.HostConfig.NetworkMode.IsContainer() {
			parts := strings.SplitN(string(child.HostConfig.NetworkMode), ":", 2)
			child, err = daemon.GetContainer(parts[1])
			if err != nil {
				if errdefs.IsNotFound(err) {
					// Trying to link to a non-existing container is not valid, and
					// should return an "invalid parameter" error. Returning a "not
					// found" error here would make the client report the container's
					// image could not be found (see moby/moby#39823)
					err = errdefs.InvalidParameter(err)
				}
				return errors.Wrapf(err, "Could not get container for %s", parts[1])
			}
		}
		if child.HostConfig.NetworkMode.IsHost() {
			return runconfig.ErrConflictHostNetworkAndLinks
		}
		if err := daemon.registerLink(container, child, alias); err != nil {
			return err
		}
	}

	// After we load all the links into the daemon
	// set them to nil on the hostconfig
	_, err := container.WriteHostConfig()
	return err
}

// conditionalMountOnStart is a platform specific helper function during the
// container start to call mount.
func (daemon *Daemon) conditionalMountOnStart(container *container.Container) error {
	return daemon.Mount(container)
}

// conditionalUnmountOnCleanup is a platform specific helper function called
// during the cleanup of a container to unmount.
func (daemon *Daemon) conditionalUnmountOnCleanup(container *container.Container) error {
	return daemon.Unmount(container)
}

func copyBlkioEntry(entries []*statsV1.BlkIOEntry) []types.BlkioStatEntry {
	out := make([]types.BlkioStatEntry, len(entries))
	for i, re := range entries {
		out[i] = types.BlkioStatEntry{
			Major: re.Major,
			Minor: re.Minor,
			Op:    re.Op,
			Value: re.Value,
		}
	}
	return out
}

func (daemon *Daemon) stats(c *container.Container) (*types.StatsJSON, error) {
	if !c.IsRunning() {
		return nil, errNotRunning(c.ID)
	}
	cs, err := daemon.containerd.Stats(context.Background(), c.ID)
	if err != nil {
		if strings.Contains(err.Error(), "container not found") {
			return nil, containerNotFound(c.ID)
		}
		return nil, err
	}
	s := &types.StatsJSON{}
	s.Read = cs.Read
	stats := cs.Metrics
	switch t := stats.(type) {
	case *statsV1.Metrics:
		return daemon.statsV1(s, t)
	case *statsV2.Metrics:
		return daemon.statsV2(s, t)
	default:
		return nil, errors.Errorf("unexpected type of metrics %+v", t)
	}
}

func (daemon *Daemon) statsV1(s *types.StatsJSON, stats *statsV1.Metrics) (*types.StatsJSON, error) {
	if stats.Blkio != nil {
		s.BlkioStats = types.BlkioStats{
			IoServiceBytesRecursive: copyBlkioEntry(stats.Blkio.IoServiceBytesRecursive),
			IoServicedRecursive:     copyBlkioEntry(stats.Blkio.IoServicedRecursive),
			IoQueuedRecursive:       copyBlkioEntry(stats.Blkio.IoQueuedRecursive),
			IoServiceTimeRecursive:  copyBlkioEntry(stats.Blkio.IoServiceTimeRecursive),
			IoWaitTimeRecursive:     copyBlkioEntry(stats.Blkio.IoWaitTimeRecursive),
			IoMergedRecursive:       copyBlkioEntry(stats.Blkio.IoMergedRecursive),
			IoTimeRecursive:         copyBlkioEntry(stats.Blkio.IoTimeRecursive),
			SectorsRecursive:        copyBlkioEntry(stats.Blkio.SectorsRecursive),
		}
	}
	if stats.CPU != nil {
		s.CPUStats = types.CPUStats{
			CPUUsage: types.CPUUsage{
				TotalUsage:        stats.CPU.Usage.Total,
				PercpuUsage:       stats.CPU.Usage.PerCPU,
				UsageInKernelmode: stats.CPU.Usage.Kernel,
				UsageInUsermode:   stats.CPU.Usage.User,
			},
			ThrottlingData: types.ThrottlingData{
				Periods:          stats.CPU.Throttling.Periods,
				ThrottledPeriods: stats.CPU.Throttling.ThrottledPeriods,
				ThrottledTime:    stats.CPU.Throttling.ThrottledTime,
			},
		}
	}

	if stats.Memory != nil {
		raw := map[string]uint64{
			"cache":                     stats.Memory.Cache,
			"rss":                       stats.Memory.RSS,
			"rss_huge":                  stats.Memory.RSSHuge,
			"mapped_file":               stats.Memory.MappedFile,
			"dirty":                     stats.Memory.Dirty,
			"writeback":                 stats.Memory.Writeback,
			"pgpgin":                    stats.Memory.PgPgIn,
			"pgpgout":                   stats.Memory.PgPgOut,
			"pgfault":                   stats.Memory.PgFault,
			"pgmajfault":                stats.Memory.PgMajFault,
			"inactive_anon":             stats.Memory.InactiveAnon,
			"active_anon":               stats.Memory.ActiveAnon,
			"inactive_file":             stats.Memory.InactiveFile,
			"active_file":               stats.Memory.ActiveFile,
			"unevictable":               stats.Memory.Unevictable,
			"hierarchical_memory_limit": stats.Memory.HierarchicalMemoryLimit,
			"hierarchical_memsw_limit":  stats.Memory.HierarchicalSwapLimit,
			"total_cache":               stats.Memory.TotalCache,
			"total_rss":                 stats.Memory.TotalRSS,
			"total_rss_huge":            stats.Memory.TotalRSSHuge,
			"total_mapped_file":         stats.Memory.TotalMappedFile,
			"total_dirty":               stats.Memory.TotalDirty,
			"total_writeback":           stats.Memory.TotalWriteback,
			"total_pgpgin":              stats.Memory.TotalPgPgIn,
			"total_pgpgout":             stats.Memory.TotalPgPgOut,
			"total_pgfault":             stats.Memory.TotalPgFault,
			"total_pgmajfault":          stats.Memory.TotalPgMajFault,
			"total_inactive_anon":       stats.Memory.TotalInactiveAnon,
			"total_active_anon":         stats.Memory.TotalActiveAnon,
			"total_inactive_file":       stats.Memory.TotalInactiveFile,
			"total_active_file":         stats.Memory.TotalActiveFile,
			"total_unevictable":         stats.Memory.TotalUnevictable,
		}
		if stats.Memory.Usage != nil {
			s.MemoryStats = types.MemoryStats{
				Stats:    raw,
				Usage:    stats.Memory.Usage.Usage,
				MaxUsage: stats.Memory.Usage.Max,
				Limit:    stats.Memory.Usage.Limit,
				Failcnt:  stats.Memory.Usage.Failcnt,
			}
		} else {
			s.MemoryStats = types.MemoryStats{
				Stats: raw,
			}
		}

		// if the container does not set memory limit, use the machineMemory
		if s.MemoryStats.Limit > daemon.machineMemory && daemon.machineMemory > 0 {
			s.MemoryStats.Limit = daemon.machineMemory
		}
	}

	if stats.Pids != nil {
		s.PidsStats = types.PidsStats{
			Current: stats.Pids.Current,
			Limit:   stats.Pids.Limit,
		}
	}

	return s, nil
}

func (daemon *Daemon) statsV2(s *types.StatsJSON, stats *statsV2.Metrics) (*types.StatsJSON, error) {
	if stats.Io != nil {
		var isbr []types.BlkioStatEntry
		for _, re := range stats.Io.Usage {
			isbr = append(isbr,
				types.BlkioStatEntry{
					Major: re.Major,
					Minor: re.Minor,
					Op:    "read",
					Value: re.Rbytes,
				},
				types.BlkioStatEntry{
					Major: re.Major,
					Minor: re.Minor,
					Op:    "write",
					Value: re.Wbytes,
				},
			)
		}
		s.BlkioStats = types.BlkioStats{
			IoServiceBytesRecursive: isbr,
			// Other fields are unsupported
		}
	}

	if stats.CPU != nil {
		s.CPUStats = types.CPUStats{
			CPUUsage: types.CPUUsage{
				TotalUsage: stats.CPU.UsageUsec * 1000,
				// PercpuUsage is not supported
				UsageInKernelmode: stats.CPU.SystemUsec * 1000,
				UsageInUsermode:   stats.CPU.UserUsec * 1000,
			},
			ThrottlingData: types.ThrottlingData{
				Periods:          stats.CPU.NrPeriods,
				ThrottledPeriods: stats.CPU.NrThrottled,
				ThrottledTime:    stats.CPU.ThrottledUsec * 1000,
			},
		}
	}

	if stats.Memory != nil {
		s.MemoryStats = types.MemoryStats{
			// Stats is not compatible with v1
			Stats: map[string]uint64{
				"anon":                   stats.Memory.Anon,
				"file":                   stats.Memory.File,
				"kernel_stack":           stats.Memory.KernelStack,
				"slab":                   stats.Memory.Slab,
				"sock":                   stats.Memory.Sock,
				"shmem":                  stats.Memory.Shmem,
				"file_mapped":            stats.Memory.FileMapped,
				"file_dirty":             stats.Memory.FileDirty,
				"file_writeback":         stats.Memory.FileWriteback,
				"anon_thp":               stats.Memory.AnonThp,
				"inactive_anon":          stats.Memory.InactiveAnon,
				"active_anon":            stats.Memory.ActiveAnon,
				"inactive_file":          stats.Memory.InactiveFile,
				"active_file":            stats.Memory.ActiveFile,
				"unevictable":            stats.Memory.Unevictable,
				"slab_reclaimable":       stats.Memory.SlabReclaimable,
				"slab_unreclaimable":     stats.Memory.SlabUnreclaimable,
				"pgfault":                stats.Memory.Pgfault,
				"pgmajfault":             stats.Memory.Pgmajfault,
				"workingset_refault":     stats.Memory.WorkingsetRefault,
				"workingset_activate":    stats.Memory.WorkingsetActivate,
				"workingset_nodereclaim": stats.Memory.WorkingsetNodereclaim,
				"pgrefill":               stats.Memory.Pgrefill,
				"pgscan":                 stats.Memory.Pgscan,
				"pgsteal":                stats.Memory.Pgsteal,
				"pgactivate":             stats.Memory.Pgactivate,
				"pgdeactivate":           stats.Memory.Pgdeactivate,
				"pglazyfree":             stats.Memory.Pglazyfree,
				"pglazyfreed":            stats.Memory.Pglazyfreed,
				"thp_fault_alloc":        stats.Memory.ThpFaultAlloc,
				"thp_collapse_alloc":     stats.Memory.ThpCollapseAlloc,
			},
			Usage: stats.Memory.Usage,
			// MaxUsage is not supported
			Limit: stats.Memory.UsageLimit,
		}
		// if the container does not set memory limit, use the machineMemory
		if s.MemoryStats.Limit > daemon.machineMemory && daemon.machineMemory > 0 {
			s.MemoryStats.Limit = daemon.machineMemory
		}
		if stats.MemoryEvents != nil {
			// Failcnt is set to the "oom" field of the "memory.events" file.
			// See https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html
			s.MemoryStats.Failcnt = stats.MemoryEvents.Oom
		}
	}

	if stats.Pids != nil {
		s.PidsStats = types.PidsStats{
			Current: stats.Pids.Current,
			Limit:   stats.Pids.Limit,
		}
	}

	return s, nil
}

// setDefaultIsolation determines the default isolation mode for the
// daemon to run in. This is only applicable on Windows
func (daemon *Daemon) setDefaultIsolation() error {
	return nil
}

// setupDaemonProcess sets various settings for the daemon's process
func setupDaemonProcess(config *config.Config) error {
	// setup the daemons oom_score_adj
	if err := setupOOMScoreAdj(config.OOMScoreAdjust); err != nil {
		return err
	}
	if err := setMayDetachMounts(); err != nil {
		logrus.WithError(err).Warn("Could not set may_detach_mounts kernel parameter")
	}
	return nil
}

// This is used to allow removal of mountpoints that may be mounted in other
// namespaces on RHEL based kernels starting from RHEL 7.4.
// Without this setting, removals on these RHEL based kernels may fail with
// "device or resource busy".
// This setting is not available in upstream kernels as it is not configurable,
// but has been in the upstream kernels since 3.15.
func setMayDetachMounts() error {
	f, err := os.OpenFile("/proc/sys/fs/may_detach_mounts", os.O_WRONLY, 0)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return errors.Wrap(err, "error opening may_detach_mounts kernel config file")
	}
	defer f.Close()

	_, err = f.WriteString("1")
	if os.IsPermission(err) {
		// Setting may_detach_mounts does not work in an
		// unprivileged container. Ignore the error, but log
		// it if we appear not to be in that situation.
		if !userns.RunningInUserNS() {
			logrus.Debugf("Permission denied writing %q to /proc/sys/fs/may_detach_mounts", "1")
		}
		return nil
	}
	return err
}

func setupOOMScoreAdj(score int) error {
	if score == 0 {
		return nil
	}
	f, err := os.OpenFile("/proc/self/oom_score_adj", os.O_WRONLY, 0)
	if err != nil {
		return err
	}
	defer f.Close()
	stringScore := strconv.Itoa(score)
	_, err = f.WriteString(stringScore)
	if os.IsPermission(err) {
		// Setting oom_score_adj does not work in an
		// unprivileged container. Ignore the error, but log
		// it if we appear not to be in that situation.
		if !userns.RunningInUserNS() {
			logrus.Debugf("Permission denied writing %q to /proc/self/oom_score_adj", stringScore)
		}
		return nil
	}

	return err
}

func (daemon *Daemon) initCPURtController(mnt, path string) error {
	if path == "/" || path == "." {
		return nil
	}

	// Recursively create cgroup to ensure that the system and all parent cgroups have values set
	// for the period and runtime as this limits what the children can be set to.
	if err := daemon.initCPURtController(mnt, filepath.Dir(path)); err != nil {
		return err
	}

	path = filepath.Join(mnt, path)
	if err := os.MkdirAll(path, 0755); err != nil {
		return err
	}
	if err := maybeCreateCPURealTimeFile(daemon.configStore.CPURealtimePeriod, "cpu.rt_period_us", path); err != nil {
		return err
	}
	return maybeCreateCPURealTimeFile(daemon.configStore.CPURealtimeRuntime, "cpu.rt_runtime_us", path)
}

func maybeCreateCPURealTimeFile(configValue int64, file string, path string) error {
	if configValue == 0 {
		return nil
	}
	return os.WriteFile(filepath.Join(path, file), []byte(strconv.FormatInt(configValue, 10)), 0700)
}

func (daemon *Daemon) setupSeccompProfile() error {
	switch profile := daemon.configStore.SeccompProfile; profile {
	case "", config.SeccompProfileDefault:
		daemon.seccompProfilePath = config.SeccompProfileDefault
	case config.SeccompProfileUnconfined:
		daemon.seccompProfilePath = config.SeccompProfileUnconfined
	default:
		daemon.seccompProfilePath = profile
		b, err := os.ReadFile(profile)
		if err != nil {
			return fmt.Errorf("opening seccomp profile (%s) failed: %v", profile, err)
		}
		daemon.seccompProfile = b
	}
	return nil
}

func getSysInfo(daemon *Daemon) *sysinfo.SysInfo {
	var siOpts []sysinfo.Opt
	if daemon.getCgroupDriver() == cgroupSystemdDriver {
		if euid := os.Getenv("ROOTLESSKIT_PARENT_EUID"); euid != "" {
			siOpts = append(siOpts, sysinfo.WithCgroup2GroupPath("/user.slice/user-"+euid+".slice"))
		}
	}
	return sysinfo.New(siOpts...)
}

func (daemon *Daemon) initLibcontainerd(ctx context.Context) error {
	var err error
	daemon.containerd, err = remote.NewClient(
		ctx,
		daemon.containerdCli,
		filepath.Join(daemon.configStore.ExecRoot, "containerd"),
		daemon.configStore.ContainerdNamespace,
		daemon,
	)
	return err
}

func recursiveUnmount(target string) error {
	return mount.RecursiveUnmount(target)
}

//go:build linux || freebsd
// +build linux freebsd

package daemon // import "github.com/docker/docker/daemon"

import (
	"bufio"
	"context"
	"fmt"
	"net"
	"os"
	"path/filepath"
	"runtime"
	"runtime/debug"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/containerd/cgroups"
	statsV1 "github.com/containerd/cgroups/stats/v1"
	statsV2 "github.com/containerd/cgroups/v2/stats"
	"github.com/containerd/containerd/pkg/userns"
	"github.com/docker/docker/api/types"
	"github.com/docker/docker/api/types/blkiodev"
	pblkiodev "github.com/docker/docker/api/types/blkiodev"
	containertypes "github.com/docker/docker/api/types/container"
	"github.com/docker/docker/container"
	"github.com/docker/docker/daemon/config"
	"github.com/docker/docker/daemon/initlayer"
	"github.com/docker/docker/errdefs"
	"github.com/docker/docker/libcontainerd/remote"
	"github.com/docker/docker/libnetwork"
	nwconfig "github.com/docker/docker/libnetwork/config"
	"github.com/docker/docker/libnetwork/drivers/bridge"
	"github.com/docker/docker/libnetwork/netlabel"
	"github.com/docker/docker/libnetwork/netutils"
	"github.com/docker/docker/libnetwork/options"
	lntypes "github.com/docker/docker/libnetwork/types"
	"github.com/docker/docker/opts"
	"github.com/docker/docker/pkg/containerfs"
	"github.com/docker/docker/pkg/idtools"
	"github.com/docker/docker/pkg/parsers"
	"github.com/docker/docker/pkg/parsers/kernel"
	"github.com/docker/docker/pkg/sysinfo"
	"github.com/docker/docker/runconfig"
	volumemounts "github.com/docker/docker/volume/mounts"
	"github.com/moby/sys/mount"
	specs "github.com/opencontainers/runtime-spec/specs-go"
	"github.com/opencontainers/selinux/go-selinux"
	"github.com/opencontainers/selinux/go-selinux/label"
	"github.com/pkg/errors"
	"github.com/sirupsen/logrus"
	"github.com/vishvananda/netlink"
	"golang.org/x/sys/unix"
)

const (
	isWindows = false

	// See https://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/tree/kernel/sched/sched.h?id=8cd9234c64c584432f6992fe944ca9e46ca8ea76#n269
	linuxMinCPUShares = 2
	linuxMaxCPUShares = 262144
	platformSupported = true
	// It's not kernel limit, we want this 6M limit to account for overhead during startup, and to supply a reasonable functional container
	linuxMinMemory = 6291456
	// constants for remapped root settings
	defaultIDSpecifier = "default"
	defaultRemappedID  = "dockremap"

	// constant for cgroup drivers
	cgroupFsDriver      = "cgroupfs"
	cgroupSystemdDriver = "systemd"
	cgroupNoneDriver    = "none"
)

type containerGetter interface {
	GetContainer(string) (*container.Container, error)
}

func getMemoryResources(config containertypes.Resources) *specs.LinuxMemory {
	memory := specs.LinuxMemory{}

	if config.Memory > 0 {
		memory.Limit = &config.Memory
	}

	if config.MemoryReservation > 0 {
		memory.Reservation = &config.MemoryReservation
	}

	if config.MemorySwap > 0 {
		memory.Swap = &config.MemorySwap
	}

	if config.MemorySwappiness != nil {
		swappiness := uint64(*config.MemorySwappiness)
		memory.Swappiness = &swappiness
	}

	if config.OomKillDisable != nil {
		memory.DisableOOMKiller = config.OomKillDisable
	}

	if config.KernelMemory != 0 {
		memory.Kernel = &config.KernelMemory
	}

	if config.KernelMemoryTCP != 0 {
		memory.KernelTCP = &config.KernelMemoryTCP
	}

	return &memory
}

func getPidsLimit(config containertypes.Resources) *specs.LinuxPids {
	if config.PidsLimit == nil {
		return nil
	}
	if *config.PidsLimit <= 0 {
		// docker API allows 0 and negative values to unset this to be consistent
		// with default values. When updating values, runc requires -1 to unset
		// the previous limit.
		return &specs.LinuxPids{Limit: -1}
	}
	return &specs.LinuxPids{Limit: *config.PidsLimit}
}

func getCPUResources(config containertypes.Resources) (*specs.LinuxCPU, error) {
	cpu := specs.LinuxCPU{}

	if config.CPUShares < 0 {
		return nil, fmt.Errorf("shares: invalid argument")
	}
	if config.CPUShares >= 0 {
		shares := uint64(config.CPUShares)
		cpu.Shares = &shares
	}

	if config.CpusetCpus != "" {
		cpu.Cpus = config.CpusetCpus
	}

	if config.CpusetMems != "" {
		cpu.Mems = config.CpusetMems
	}

	if config.NanoCPUs > 0 {
		// https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt
		period := uint64(100 * time.Millisecond / time.Microsecond)
		quota := config.NanoCPUs * int64(period) / 1e9
		cpu.Period = &period
		cpu.Quota = &quota
	}

	if config.CPUPeriod != 0 {
		period := uint64(config.CPUPeriod)
		cpu.Period = &period
	}

	if config.CPUQuota != 0 {
		q := config.CPUQuota
		cpu.Quota = &q
	}

	if config.CPURealtimePeriod != 0 {
		period := uint64(config.CPURealtimePeriod)
		cpu.RealtimePeriod = &period
	}

	if config.CPURealtimeRuntime != 0 {
		c := config.CPURealtimeRuntime
		cpu.RealtimeRuntime = &c
	}

	return &cpu, nil
}

func getBlkioWeightDevices(config containertypes.Resources) ([]specs.LinuxWeightDevice, error) {
	var stat unix.Stat_t
	var blkioWeightDevices []specs.LinuxWeightDevice

	for _, weightDevice := range config.BlkioWeightDevice {
		if err := unix.Stat(weightDevice.Path, &stat); err != nil {
			return nil, errors.WithStack(&os.PathError{Op: "stat", Path: weightDevice.Path, Err: err})
		}
		weight := weightDevice.Weight
		d := specs.LinuxWeightDevice{Weight: &weight}
		// The type is 32bit on mips.
		d.Major = int64(unix.Major(uint64(stat.Rdev))) //nolint: unconvert
		d.Minor = int64(unix.Minor(uint64(stat.Rdev))) //nolint: unconvert
		blkioWeightDevices = append(blkioWeightDevices, d)
	}

	return blkioWeightDevices, nil
}

func (daemon *Daemon) parseSecurityOpt(container *container.Container, hostConfig *containertypes.HostConfig) error {
	container.NoNewPrivileges = daemon.configStore.NoNewPrivileges
	return parseSecurityOpt(container, hostConfig)
}

func parseSecurityOpt(container *container.Container, config *containertypes.HostConfig) error {
	var (
		labelOpts []string
		err       error
	)

	for _, opt := range config.SecurityOpt {
		if opt == "no-new-privileges" {
			container.NoNewPrivileges = true
			continue
		}
		if opt == "disable" {
			labelOpts = append(labelOpts, "disable")
			continue
		}

		var con []string
		if strings.Contains(opt, "=") {
			con = strings.SplitN(opt, "=", 2)
		} else if strings.Contains(opt, ":") {
			con = strings.SplitN(opt, ":", 2)
			logrus.Warn("Security options with `:` as a separator are deprecated and will be completely unsupported in 17.04, use `=` instead.")
		}
		if len(con) != 2 {
			return fmt.Errorf("invalid --security-opt 1: %q", opt)
		}

		switch con[0] {
		case "label":
			labelOpts = append(labelOpts, con[1])
		case "apparmor":
			container.AppArmorProfile = con[1]
		case "seccomp":
			container.SeccompProfile = con[1]
		case "no-new-privileges":
			noNewPrivileges, err := strconv.ParseBool(con[1])
			if err != nil {
				return fmt.Errorf("invalid --security-opt 2: %q", opt)
			}
			container.NoNewPrivileges = noNewPrivileges
		default:
			return fmt.Errorf("invalid --security-opt 2: %q", opt)
		}
	}

	container.ProcessLabel, container.MountLabel, err = label.InitLabels(labelOpts)
	return err
}

func getBlkioThrottleDevices(devs []*blkiodev.ThrottleDevice) ([]specs.LinuxThrottleDevice, error) {
	var throttleDevices []specs.LinuxThrottleDevice
	var stat unix.Stat_t

	for _, d := range devs {
		if err := unix.Stat(d.Path, &stat); err != nil {
			return nil, errors.WithStack(&os.PathError{Op: "stat", Path: d.Path, Err: err})
		}
		d := specs.LinuxThrottleDevice{Rate: d.Rate}
		// the type is 32bit on mips
		d.Major = int64(unix.Major(uint64(stat.Rdev))) //nolint: unconvert
		d.Minor = int64(unix.Minor(uint64(stat.Rdev))) //nolint: unconvert
		throttleDevices = append(throttleDevices, d)
	}

	return throttleDevices, nil
}

// adjustParallelLimit takes a number of objects and a proposed limit and
// figures out if it's reasonable (and adjusts it accordingly). This is only
// used for daemon startup, which does a lot of parallel loading of containers
// (and if we exceed RLIMIT_NOFILE then we're in trouble).
func adjustParallelLimit(n int, limit int) int {
	// Rule-of-thumb overhead factor (how many files will each goroutine open
	// simultaneously). Yes, this is ugly but to be frank this whole thing is
	// ugly.
	const overhead = 2

	// On Linux, we need to ensure that parallelStartupJobs doesn't cause us to
	// exceed RLIMIT_NOFILE. If parallelStartupJobs is too large, we reduce it
	// and give a warning (since in theory the user should increase their
	// ulimits to the largest possible value for dockerd).
	var rlim unix.Rlimit
	if err := unix.Getrlimit(unix.RLIMIT_NOFILE, &rlim); err != nil {
		logrus.Warnf("Couldn't find dockerd's RLIMIT_NOFILE to double-check startup parallelism factor: %v", err)
		return limit
	}
	softRlimit := int(rlim.Cur)

	// Much fewer containers than RLIMIT_NOFILE. No need to adjust anything.
	if softRlimit > overhead*n {
		return limit
	}

	// RLIMIT_NOFILE big enough, no need to adjust anything.
	if softRlimit > overhead*limit {
		return limit
	}

	logrus.Warnf("Found dockerd's open file ulimit (%v) is far too small -- consider increasing it significantly (at least %v)", softRlimit, overhead*limit)
	return softRlimit / overhead
}

// adaptContainerSettings is called during container creation to modify any
// settings necessary in the HostConfig structure.
func (daemon *Daemon) adaptContainerSettings(hostConfig *containertypes.HostConfig, adjustCPUShares bool) error {
	if adjustCPUShares && hostConfig.CPUShares > 0 {
		// Handle unsupported CPUShares
		if hostConfig.CPUShares < linuxMinCPUShares {
			logrus.Warnf("Changing requested CPUShares of %d to minimum allowed of %d", hostConfig.CPUShares, linuxMinCPUShares)
			hostConfig.CPUShares = linuxMinCPUShares
		} else if hostConfig.CPUShares > linuxMaxCPUShares {
			logrus.Warnf("Changing requested CPUShares of %d to maximum allowed of %d", hostConfig.CPUShares, linuxMaxCPUShares)
			hostConfig.CPUShares = linuxMaxCPUShares
		}
	}
	if hostConfig.Memory > 0 && hostConfig.MemorySwap == 0 {
		// By default, MemorySwap is set to twice the size of Memory.
		hostConfig.MemorySwap = hostConfig.Memory * 2
	}
	if hostConfig.ShmSize == 0 {
		hostConfig.ShmSize = config.DefaultShmSize
		if daemon.configStore != nil {
			hostConfig.ShmSize = int64(daemon.configStore.ShmSize)
		}
	}
	// Set default IPC mode, if unset for container
	if hostConfig.IpcMode.IsEmpty() {
		m := config.DefaultIpcMode
		if daemon.configStore != nil {
			m = containertypes.IpcMode(daemon.configStore.IpcMode)
		}
		hostConfig.IpcMode = m
	}

	// Set default cgroup namespace mode, if unset for container
	if hostConfig.CgroupnsMode.IsEmpty() {
		// for cgroup v2: unshare cgroupns even for privileged containers
		// https://github.com/containers/libpod/pull/4374#issuecomment-549776387
		if hostConfig.Privileged && cgroups.Mode() != cgroups.Unified {
			hostConfig.CgroupnsMode = containertypes.CgroupnsModeHost
		} else {
			m := containertypes.CgroupnsModeHost
			if cgroups.Mode() == cgroups.Unified {
				m = containertypes.CgroupnsModePrivate
			}
			if daemon.configStore != nil {
				m = containertypes.CgroupnsMode(daemon.configStore.CgroupNamespaceMode)
			}
			hostConfig.CgroupnsMode = m
		}
	}

	adaptSharedNamespaceContainer(daemon, hostConfig)

	var err error
	secOpts, err := daemon.generateSecurityOpt(hostConfig)
	if err != nil {
		return err
	}
	hostConfig.SecurityOpt = append(hostConfig.SecurityOpt, secOpts...)
	if hostConfig.OomKillDisable == nil {
		defaultOomKillDisable := false
		hostConfig.OomKillDisable = &defaultOomKillDisable
	}

	return nil
}

// adaptSharedNamespaceContainer replaces container name with its ID in hostConfig.
// To be more precisely, it modifies `container:name` to `container:ID` of PidMode, IpcMode
// and NetworkMode.
//
// When a container shares its namespace with another container, use ID can keep the namespace
// sharing connection between the two containers even the another container is renamed.
func adaptSharedNamespaceContainer(daemon containerGetter, hostConfig *containertypes.HostConfig) {
	containerPrefix := "container:"
	if hostConfig.PidMode.IsContainer() {
		pidContainer := hostConfig.PidMode.Container()
		// if there is any error returned here, we just ignore it and leave it to be
		// handled in the following logic
		if c, err := daemon.GetContainer(pidContainer); err == nil {
			hostConfig.PidMode = containertypes.PidMode(containerPrefix + c.ID)
		}
	}
	if hostConfig.IpcMode.IsContainer() {
		ipcContainer := hostConfig.IpcMode.Container()
		if c, err := daemon.GetContainer(ipcContainer); err == nil {
			hostConfig.IpcMode = containertypes.IpcMode(containerPrefix + c.ID)
		}
	}
	if hostConfig.NetworkMode.IsContainer() {
		netContainer := hostConfig.NetworkMode.ConnectedContainer()
		if c, err := daemon.GetContainer(netContainer); err == nil {
			hostConfig.NetworkMode = containertypes.NetworkMode(containerPrefix + c.ID)
		}
	}
}

// verifyPlatformContainerResources performs platform-specific validation of the container's resource-configuration
func verifyPlatformContainerResources(resources *containertypes.Resources, sysInfo *sysinfo.SysInfo, update bool) (warnings []string, err error) {
	fixMemorySwappiness(resources)

	// memory subsystem checks and adjustments
	if resources.Memory != 0 && resources.Memory < linuxMinMemory {
		return warnings, fmt.Errorf("Minimum memory limit allowed is 6MB")
	}
	if resources.Memory > 0 && !sysInfo.MemoryLimit {
		warnings = append(warnings, "Your kernel does not support memory limit capabilities or the cgroup is not mounted. Limitation discarded.")
		resources.Memory = 0
		resources.MemorySwap = -1
	}
	if resources.Memory > 0 && resources.MemorySwap != -1 && !sysInfo.SwapLimit {
		warnings = append(warnings, "Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.")
		resources.MemorySwap = -1
	}
	if resources.Memory > 0 && resources.MemorySwap > 0 && resources.MemorySwap < resources.Memory {
		return warnings, fmt.Errorf("Minimum memoryswap limit should be larger than memory limit, see usage")
	}
	if resources.Memory == 0 && resources.MemorySwap > 0 && !update {
		return warnings, fmt.Errorf("You should always set the Memory limit when using Memoryswap limit, see usage")
	}
	if resources.MemorySwappiness != nil && !sysInfo.MemorySwappiness {
		warnings = append(warnings, "Your kernel does not support memory swappiness capabilities or the cgroup is not mounted. Memory swappiness discarded.")
		resources.MemorySwappiness = nil
	}
	if resources.MemorySwappiness != nil {
		swappiness := *resources.MemorySwappiness
		if swappiness < 0 || swappiness > 100 {
			return warnings, fmt.Errorf("Invalid value: %v, valid memory swappiness range is 0-100", swappiness)
		}
	}
	if resources.MemoryReservation > 0 && !sysInfo.MemoryReservation {
		warnings = append(warnings, "Your kernel does not support memory soft limit capabilities or the cgroup is not mounted. Limitation discarded.")
		resources.MemoryReservation = 0
	}
	if resources.MemoryReservation > 0 && resources.MemoryReservation < linuxMinMemory {
		return warnings, fmt.Errorf("Minimum memory reservation allowed is 6MB")
	}
	if resources.Memory > 0 && resources.MemoryReservation > 0 && resources.Memory < resources.MemoryReservation {
		return warnings, fmt.Errorf("Minimum memory limit can not be less than memory reservation limit, see usage")
	}
	if resources.KernelMemory > 0 {
		// Kernel memory limit is not supported on cgroup v2.
		// Even on cgroup v1, kernel memory limit (`kmem.limit_in_bytes`) has been deprecated since kernel 5.4.
		// https://github.com/torvalds/linux/commit/0158115f702b0ba208ab0b5adf44cae99b3ebcc7
		if !sysInfo.KernelMemory {
			warnings = append(warnings, "Your kernel does not support kernel memory limit capabilities or the cgroup is not mounted. Limitation discarded.")
			resources.KernelMemory = 0
		}
		if resources.KernelMemory > 0 && resources.KernelMemory < linuxMinMemory {
			return warnings, fmt.Errorf("Minimum kernel memory limit allowed is 6MB")
		}
		if !kernel.CheckKernelVersion(4, 0, 0) {
			warnings = append(warnings, "You specified a kernel memory limit on a kernel older than 4.0. Kernel memory limits are experimental on older kernels, it won't work as expected and can cause your system to be unstable.")
		}
	}
	if resources.OomKillDisable != nil && !sysInfo.OomKillDisable {
		// only produce warnings if the setting wasn't to *disable* the OOM Kill; no point
		// warning the caller if they already wanted the feature to be off
		if *resources.OomKillDisable {
			warnings = append(warnings, "Your kernel does not support OomKillDisable. OomKillDisable discarded.")
		}
		resources.OomKillDisable = nil
	}
	if resources.OomKillDisable != nil && *resources.OomKillDisable && resources.Memory == 0 {
		warnings = append(warnings, "OOM killer is disabled for the container, but no memory limit is set, this can result in the system running out of resources.")
	}
	if resources.PidsLimit != nil && !sysInfo.PidsLimit {
		if *resources.PidsLimit > 0 {
			warnings = append(warnings, "Your kernel does not support PIDs limit capabilities or the cgroup is not mounted. PIDs limit discarded.")
		}
		resources.PidsLimit = nil
	}

	// cpu subsystem checks and adjustments
	if resources.NanoCPUs > 0 && resources.CPUPeriod > 0 {
		return warnings, fmt.Errorf("Conflicting options: Nano CPUs and CPU Period cannot both be set")
	}
	if resources.NanoCPUs > 0 && resources.CPUQuota > 0 {
		return warnings, fmt.Errorf("Conflicting options: Nano CPUs and CPU Quota cannot both be set")
	}
	if resources.NanoCPUs > 0 && !sysInfo.CPUCfs {
		return warnings, fmt.Errorf("NanoCPUs can not be set, as your kernel does not support CPU CFS scheduler or the cgroup is not mounted")
	}
	// The highest precision we could get on Linux is 0.001, by setting
	//   cpu.cfs_period_us=1000ms
	//   cpu.cfs_quota=1ms
	// See the following link for details:
	// https://www.kernel.org/doc/Documentation/scheduler/sched-bwc.txt
	// Here we don't set the lower limit and it is up to the underlying platform (e.g., Linux) to return an error.
	// The error message is 0.01 so that this is consistent with Windows
	if resources.NanoCPUs < 0 || resources.NanoCPUs > int64(sysinfo.NumCPU())*1e9 {
		return warnings, fmt.Errorf("Range of CPUs is from 0.01 to %d.00, as there are only %d CPUs available", sysinfo.NumCPU(), sysinfo.NumCPU())
	}

	if resources.CPUShares > 0 && !sysInfo.CPUShares {
		warnings = append(warnings, "Your kernel does not support CPU shares or the cgroup is not mounted. Shares discarded.")
		resources.CPUShares = 0
	}
	if (resources.CPUPeriod != 0 || resources.CPUQuota != 0) && !sysInfo.CPUCfs {
		warnings = append(warnings, "Your kernel does not support CPU CFS scheduler. CPU period/quota discarded.")
		resources.CPUPeriod = 0
		resources.CPUQuota = 0
	}
	if resources.CPUPeriod != 0 && (resources.CPUPeriod < 1000 || resources.CPUPeriod > 1000000) {
		return warnings, fmt.Errorf("CPU cfs period can not be less than 1ms (i.e. 1000) or larger than 1s (i.e. 1000000)")
	}
	if resources.CPUQuota > 0 && resources.CPUQuota < 1000 {
		return warnings, fmt.Errorf("CPU cfs quota can not be less than 1ms (i.e. 1000)")
	}
	if resources.CPUPercent > 0 {
		warnings = append(warnings, fmt.Sprintf("%s does not support CPU percent. Percent discarded.", runtime.GOOS))
		resources.CPUPercent = 0
	}

	// cpuset subsystem checks and adjustments
	if (resources.CpusetCpus != "" || resources.CpusetMems != "") && !sysInfo.Cpuset {
		warnings = append(warnings, "Your kernel does not support cpuset or the cgroup is not mounted. Cpuset discarded.")
		resources.CpusetCpus = ""
		resources.CpusetMems = ""
	}
	cpusAvailable, err := sysInfo.IsCpusetCpusAvailable(resources.CpusetCpus)
	if err != nil {
		return warnings, errors.Wrapf(err, "Invalid value %s for cpuset cpus", resources.CpusetCpus)
	}
	if !cpusAvailable {
		return warnings, fmt.Errorf("Requested CPUs are not available - requested %s, available: %s", resources.CpusetCpus, sysInfo.Cpus)
	}
	memsAvailable, err := sysInfo.IsCpusetMemsAvailable(resources.CpusetMems)
	if err != nil {
		return warnings, errors.Wrapf(err, "Invalid value %s for cpuset mems", resources.CpusetMems)
	}
	if !memsAvailable {
		return warnings, fmt.Errorf("Requested memory nodes are not available - requested %s, available: %s", resources.CpusetMems, sysInfo.Mems)
	}

	// blkio subsystem checks and adjustments
	if resources.BlkioWeight > 0 && !sysInfo.BlkioWeight {
		warnings = append(warnings, "Your kernel does not support Block I/O weight or the cgroup is not mounted. Weight discarded.")
		resources.BlkioWeight = 0
	}
	if resources.BlkioWeight > 0 && (resources.BlkioWeight < 10 || resources.BlkioWeight > 1000) {
		return warnings, fmt.Errorf("Range of blkio weight is from 10 to 1000")
	}
	if resources.IOMaximumBandwidth != 0 || resources.IOMaximumIOps != 0 {
		return warnings, fmt.Errorf("Invalid QoS settings: %s does not support Maximum IO Bandwidth or Maximum IO IOps", runtime.GOOS)
	}
	if len(resources.BlkioWeightDevice) > 0 && !sysInfo.BlkioWeightDevice {
		warnings = append(warnings, "Your kernel does not support Block I/O weight_device or the cgroup is not mounted. Weight-device discarded.")
		resources.BlkioWeightDevice = []*pblkiodev.WeightDevice{}
	}
	if len(resources.BlkioDeviceReadBps) > 0 && !sysInfo.BlkioReadBpsDevice {
		warnings = append(warnings, "Your kernel does not support BPS Block I/O read limit or the cgroup is not mounted. Block I/O BPS read limit discarded.")
		resources.BlkioDeviceReadBps = []*pblkiodev.ThrottleDevice{}
	}
	if len(resources.BlkioDeviceWriteBps) > 0 && !sysInfo.BlkioWriteBpsDevice {
		warnings = append(warnings, "Your kernel does not support BPS Block I/O write limit or the cgroup is not mounted. Block I/O BPS write limit discarded.")
		resources.BlkioDeviceWriteBps = []*pblkiodev.ThrottleDevice{}

	}
	if len(resources.BlkioDeviceReadIOps) > 0 && !sysInfo.BlkioReadIOpsDevice {
		warnings = append(warnings, "Your kernel does not support IOPS Block read limit or the cgroup is not mounted. Block I/O IOPS read limit discarded.")
		resources.BlkioDeviceReadIOps = []*pblkiodev.ThrottleDevice{}
	}
	if len(resources.BlkioDeviceWriteIOps) > 0 && !sysInfo.BlkioWriteIOpsDevice {
		warnings = append(warnings, "Your kernel does not support IOPS Block write limit or the cgroup is not mounted. Block I/O IOPS write limit discarded.")
		resources.BlkioDeviceWriteIOps = []*pblkiodev.ThrottleDevice{}
	}

	return warnings, nil
}

func (daemon *Daemon) getCgroupDriver() string {
	if UsingSystemd(daemon.configStore) {
		return cgroupSystemdDriver
	}
	if daemon.Rootless() {
		return cgroupNoneDriver
	}
	return cgroupFsDriver
}

// getCD gets the raw value of the native.cgroupdriver option, if set.
func getCD(config *config.Config) string {
	for _, option := range config.ExecOptions {
		key, val, err := parsers.ParseKeyValueOpt(option)
		if err != nil || !strings.EqualFold(key, "native.cgroupdriver") {
			continue
		}
		return val
	}
	return ""
}

// verifyCgroupDriver validates native.cgroupdriver
func verifyCgroupDriver(config *config.Config) error {
	cd := getCD(config)
	if cd == "" || cd == cgroupFsDriver || cd == cgroupSystemdDriver {
		return nil
	}
	if cd == cgroupNoneDriver {
		return fmt.Errorf("native.cgroupdriver option %s is internally used and cannot be specified manually", cd)
	}
	return fmt.Errorf("native.cgroupdriver option %s not supported", cd)
}

// UsingSystemd returns true if cli option includes native.cgroupdriver=systemd
func UsingSystemd(config *config.Config) bool {
	cd := getCD(config)

	if cd == cgroupSystemdDriver {
		return true
	}
	// On cgroup v2 hosts, default to systemd driver
	if cd == "" && cgroups.Mode() == cgroups.Unified && isRunningSystemd() {
		return true
	}
	return false
}

var (
	runningSystemd bool
	detectSystemd  sync.Once
)

// isRunningSystemd checks whether the host was booted with systemd as its init
// system. This functions similarly to systemd's `sd_booted(3)`: internally, it
// checks whether /run/systemd/system/ exists and is a directory.
// http://www.freedesktop.org/software/systemd/man/sd_booted.html
//
// NOTE: This function comes from package github.com/coreos/go-systemd/util
// It was borrowed here to avoid a dependency on cgo.
func isRunningSystemd() bool {
	detectSystemd.Do(func() {
		fi, err := os.Lstat("/run/systemd/system")
		if err != nil {
			return
		}
		runningSystemd = fi.IsDir()
	})
	return runningSystemd
}

// verifyPlatformContainerSettings performs platform-specific validation of the
// hostconfig and config structures.
func verifyPlatformContainerSettings(daemon *Daemon, hostConfig *containertypes.HostConfig, update bool) (warnings []string, err error) {
	if hostConfig == nil {
		return nil, nil
	}
	sysInfo := daemon.RawSysInfo()

	w, err := verifyPlatformContainerResources(&hostConfig.Resources, sysInfo, update)

	// no matter err is nil or not, w could have data in itself.
	warnings = append(warnings, w...)

	if err != nil {
		return warnings, err
	}

	if !hostConfig.IpcMode.Valid() {
		return warnings, errors.Errorf("invalid IPC mode: %v", hostConfig.IpcMode)
	}
	if !hostConfig.PidMode.Valid() {
		return warnings, errors.Errorf("invalid PID mode: %v", hostConfig.PidMode)
	}
	if hostConfig.ShmSize < 0 {
		return warnings, fmt.Errorf("SHM size can not be less than 0")
	}
	if !hostConfig.UTSMode.Valid() {
		return warnings, errors.Errorf("invalid UTS mode: %v", hostConfig.UTSMode)
	}

	if hostConfig.OomScoreAdj < -1000 || hostConfig.OomScoreAdj > 1000 {
		return warnings, fmt.Errorf("Invalid value %d, range for oom score adj is [-1000, 1000]", hostConfig.OomScoreAdj)
	}

	// ip-forwarding does not affect container with '--net=host' (or '--net=none')
	if sysInfo.IPv4ForwardingDisabled && !(hostConfig.NetworkMode.IsHost() || hostConfig.NetworkMode.IsNone()) {
		warnings = append(warnings, "IPv4 forwarding is disabled. Networking will not work.")
	}
	if hostConfig.NetworkMode.IsHost() && len(hostConfig.PortBindings) > 0 {
		warnings = append(warnings, "Published ports are discarded when using host network mode")
	}

	// check for various conflicting options with user namespaces
	if daemon.configStore.RemappedRoot != "" && hostConfig.UsernsMode.IsPrivate() {
		if hostConfig.Privileged {
			return warnings, fmt.Errorf("privileged mode is incompatible with user namespaces.  You must run the container in the host namespace when running privileged mode")
		}
		if hostConfig.NetworkMode.IsHost() && !hostConfig.UsernsMode.IsHost() {
			return warnings, fmt.Errorf("cannot share the host's network namespace when user namespaces are enabled")
		}
		if hostConfig.PidMode.IsHost() && !hostConfig.UsernsMode.IsHost() {
			return warnings, fmt.Errorf("cannot share the host PID namespace when user namespaces are enabled")
		}
	}
	if hostConfig.CgroupParent != "" && UsingSystemd(daemon.configStore) {
		// CgroupParent for systemd cgroup should be named as "xxx.slice"
		if len(hostConfig.CgroupParent) <= 6 || !strings.HasSuffix(hostConfig.CgroupParent, ".slice") {
			return warnings, fmt.Errorf("cgroup-parent for systemd cgroup should be a valid slice named as \"xxx.slice\"")
		}
	}
	if hostConfig.Runtime == "" {
		hostConfig.Runtime = daemon.configStore.GetDefaultRuntimeName()
	}

	if _, err := daemon.getRuntime(hostConfig.Runtime); err != nil {
		return warnings, err
	}

	parser := volumemounts.NewParser()
	for dest := range hostConfig.Tmpfs {
		if err := parser.ValidateTmpfsMountDestination(dest); err != nil {
			return warnings, err
		}
	}

	if !hostConfig.CgroupnsMode.Valid() {
		return warnings, fmt.Errorf("invalid cgroup namespace mode: %v", hostConfig.CgroupnsMode)
	}
	if hostConfig.CgroupnsMode.IsPrivate() {
		if !sysInfo.CgroupNamespaces {
			warnings = append(warnings, "Your kernel does not support cgroup namespaces.  Cgroup namespace setting discarded.")
		}
	}

	return warnings, nil
}

// verifyDaemonSettings performs validation of daemon config struct
func verifyDaemonSettings(conf *config.Config) error {
	if conf.ContainerdNamespace == conf.ContainerdPluginNamespace {
		return errors.New("containers namespace and plugins namespace cannot be the same")
	}
	// Check for mutually incompatible config options
	if conf.BridgeConfig.Iface != "" && conf.BridgeConfig.IP != "" {
		return fmt.Errorf("You specified -b & --bip, mutually exclusive options. Please specify only one")
	}
	if !conf.BridgeConfig.EnableIPTables && !conf.BridgeConfig.InterContainerCommunication {
		return fmt.Errorf("You specified --iptables=false with --icc=false. ICC=false uses iptables to function. Please set --icc or --iptables to true")
	}
	if conf.BridgeConfig.EnableIP6Tables && !conf.Experimental {
		return fmt.Errorf("ip6tables rules are only available if experimental features are enabled")
	}
	if !conf.BridgeConfig.EnableIPTables && conf.BridgeConfig.EnableIPMasq {
		conf.BridgeConfig.EnableIPMasq = false
	}
	if err := verifyCgroupDriver(conf); err != nil {
		return err
	}
	if conf.CgroupParent != "" && UsingSystemd(conf) {
		if len(conf.CgroupParent) <= 6 || !strings.HasSuffix(conf.CgroupParent, ".slice") {
			return fmt.Errorf("cgroup-parent for systemd cgroup should be a valid slice named as \"xxx.slice\"")
		}
	}

	if conf.Rootless && UsingSystemd(conf) && cgroups.Mode() != cgroups.Unified {
		return fmt.Errorf("exec-opt native.cgroupdriver=systemd requires cgroup v2 for rootless mode")
	}

	configureRuntimes(conf)
	if rtName := conf.GetDefaultRuntimeName(); rtName != "" {
		if conf.GetRuntime(rtName) == nil {
			return fmt.Errorf("specified default runtime '%s' does not exist", rtName)
		}
	}
	return nil
}

// checkSystem validates platform-specific requirements
func checkSystem() error {
	return nil
}

// configureMaxThreads sets the Go runtime max threads threshold
// which is 90% of the kernel setting from /proc/sys/kernel/threads-max
func configureMaxThreads(config *config.Config) error {
	mt, err := os.ReadFile("/proc/sys/kernel/threads-max")
	if err != nil {
		return err
	}
	mtint, err := strconv.Atoi(strings.TrimSpace(string(mt)))
	if err != nil {
		return err
	}
	maxThreads := (mtint / 100) * 90
	debug.SetMaxThreads(maxThreads)
	logrus.Debugf("Golang's threads limit set to %d", maxThreads)
	return nil
}

func overlaySupportsSelinux() (bool, error) {
	f, err := os.Open("/proc/kallsyms")
	if err != nil {
		if os.IsNotExist(err) {
			return false, nil
		}
		return false, err
	}
	defer f.Close()

	s := bufio.NewScanner(f)
	for s.Scan() {
		if strings.HasSuffix(s.Text(), " security_inode_copy_up") {
			return true, nil
		}
	}

	return false, s.Err()
}

// configureKernelSecuritySupport configures and validates security support for the kernel
func configureKernelSecuritySupport(config *config.Config, driverName string) error {
	if config.EnableSelinuxSupport {
		if !selinux.GetEnabled() {
			logrus.Warn("Docker could not enable SELinux on the host system")
			return nil
		}

		if driverName == "overlay" || driverName == "overlay2" {
			// If driver is overlay or overlay2, make sure kernel
			// supports selinux with overlay.
			supported, err := overlaySupportsSelinux()
			if err != nil {
				return err
			}

			if !supported {
				logrus.Warnf("SELinux is not supported with the %v graph driver on this kernel", driverName)
			}
		}
	} else {
		selinux.SetDisabled()
	}
	return nil
}

// initNetworkController initializes the libnetwork controller and configures
// network settings. If there's active sandboxes, configuration changes will not
// take effect.
func (daemon *Daemon) initNetworkController(activeSandboxes map[string]interface{}) error {
	netOptions, err := daemon.networkOptions(daemon.PluginStore, activeSandboxes)
	if err != nil {
		return err
	}

	daemon.netController, err = libnetwork.New(netOptions...)
	if err != nil {
		return fmt.Errorf("error obtaining controller instance: %v", err)
	}

	if len(activeSandboxes) > 0 {
		logrus.Info("there are running containers, updated network configuration will not take affect")
	} else if err := configureNetworking(daemon.netController, daemon.configStore); err != nil {
		return err
	}

	// Set HostGatewayIP to the default bridge's IP if it is empty
	setHostGatewayIP(daemon.netController, daemon.configStore)
	return nil
}

func configureNetworking(controller libnetwork.NetworkController, conf *config.Config) error {
	// Initialize default network on "null"
	if n, _ := controller.NetworkByName("none"); n == nil {
		if _, err := controller.NewNetwork("null", "none", "", libnetwork.NetworkOptionPersist(true)); err != nil {
			return errors.Wrap(err, `error creating default "null" network`)
		}
	}

	// Initialize default network on "host"
	if n, _ := controller.NetworkByName("host"); n == nil {
		if _, err := controller.NewNetwork("host", "host", "", libnetwork.NetworkOptionPersist(true)); err != nil {
			return errors.Wrap(err, `error creating default "host" network`)
		}
	}

	// Clear stale bridge network
	if n, err := controller.NetworkByName("bridge"); err == nil {
		if err = n.Delete(); err != nil {
			return errors.Wrap(err, `could not delete the default "bridge"" network`)
		}
		if len(conf.NetworkConfig.DefaultAddressPools.Value()) > 0 && !conf.LiveRestoreEnabled {
			removeDefaultBridgeInterface()
		}
	}

	if !conf.DisableBridge {
		// Initialize default driver "bridge"
		if err := initBridgeDriver(controller, conf); err != nil {
			return err
		}
	} else {
		removeDefaultBridgeInterface()
	}

	return nil
}

// setHostGatewayIP sets cfg.HostGatewayIP to the default bridge's IP if it is empty.
func setHostGatewayIP(controller libnetwork.NetworkController, config *config.Config) {
	if config.HostGatewayIP != nil {
		return
	}
	if n, err := controller.NetworkByName("bridge"); err == nil {
		v4Info, v6Info := n.Info().IpamInfo()
		var gateway net.IP
		if len(v4Info) > 0 {
			gateway = v4Info[0].Gateway.IP
		} else if len(v6Info) > 0 {
			gateway = v6Info[0].Gateway.IP
		}
		config.HostGatewayIP = gateway
	}
}

func driverOptions(config *config.Config) nwconfig.Option {
	return nwconfig.OptionDriverConfig("bridge", options.Generic{
		netlabel.GenericData: options.Generic{
			"EnableIPForwarding":  config.BridgeConfig.EnableIPForward,
			"EnableIPTables":      config.BridgeConfig.EnableIPTables,
			"EnableIP6Tables":     config.BridgeConfig.EnableIP6Tables,
			"EnableUserlandProxy": config.BridgeConfig.EnableUserlandProxy,
			"UserlandProxyPath":   config.BridgeConfig.UserlandProxyPath,
		},
	})
}

func initBridgeDriver(controller libnetwork.NetworkController, config *config.Config) error {
	bridgeName := bridge.DefaultBridgeName
	if config.BridgeConfig.Iface != "" {
		bridgeName = config.BridgeConfig.Iface
	}
	netOption := map[string]string{
		bridge.BridgeName:         bridgeName,
		bridge.DefaultBridge:      strconv.FormatBool(true),
		netlabel.DriverMTU:        strconv.Itoa(config.Mtu),
		bridge.EnableIPMasquerade: strconv.FormatBool(config.BridgeConfig.EnableIPMasq),
		bridge.EnableICC:          strconv.FormatBool(config.BridgeConfig.InterContainerCommunication),
	}

	// --ip processing
	if config.BridgeConfig.DefaultIP != nil {
		netOption[bridge.DefaultBindingIP] = config.BridgeConfig.DefaultIP.String()
	}

	ipamV4Conf := &libnetwork.IpamConf{AuxAddresses: make(map[string]string)}

	nwList, nw6List, err := netutils.ElectInterfaceAddresses(bridgeName)
	if err != nil {
		return errors.Wrap(err, "list bridge addresses failed")
	}

	nw := nwList[0]
	if len(nwList) > 1 && config.BridgeConfig.FixedCIDR != "" {
		_, fCIDR, err := net.ParseCIDR(config.BridgeConfig.FixedCIDR)
		if err != nil {
			return errors.Wrap(err, "parse CIDR failed")
		}
		// Iterate through in case there are multiple addresses for the bridge
		for _, entry := range nwList {
			if fCIDR.Contains(entry.IP) {
				nw = entry
				break
			}
		}
	}

	ipamV4Conf.PreferredPool = lntypes.GetIPNetCanonical(nw).String()
	hip, _ := lntypes.GetHostPartIP(nw.IP, nw.Mask)
	if hip.IsGlobalUnicast() {
		ipamV4Conf.Gateway = nw.IP.String()
	}

	if config.BridgeConfig.IP != "" {
		ip, ipNet, err := net.ParseCIDR(config.BridgeConfig.IP)
		if err != nil {
			return err
		}
		ipamV4Conf.PreferredPool = ipNet.String()
		ipamV4Conf.Gateway = ip.String()
	} else if bridgeName == bridge.DefaultBridgeName && ipamV4Conf.PreferredPool != "" {
		logrus.Infof("Default bridge (%s) is assigned with an IP address %s. Daemon option --bip can be used to set a preferred IP address", bridgeName, ipamV4Conf.PreferredPool)
	}

	if config.BridgeConfig.FixedCIDR != "" {
		_, fCIDR, err := net.ParseCIDR(config.BridgeConfig.FixedCIDR)
		if err != nil {
			return err
		}

		ipamV4Conf.SubPool = fCIDR.String()
	}

	if config.BridgeConfig.DefaultGatewayIPv4 != nil {
		ipamV4Conf.AuxAddresses["DefaultGatewayIPv4"] = config.BridgeConfig.DefaultGatewayIPv4.String()
	}

	var (
		deferIPv6Alloc bool
		ipamV6Conf     *libnetwork.IpamConf
	)

	if config.BridgeConfig.EnableIPv6 && config.BridgeConfig.FixedCIDRv6 == "" {
		return errdefs.InvalidParameter(errors.New("IPv6 is enabled for the default bridge, but no subnet is configured. Specify an IPv6 subnet using --fixed-cidr-v6"))
	} else if config.BridgeConfig.FixedCIDRv6 != "" {
		_, fCIDRv6, err := net.ParseCIDR(config.BridgeConfig.FixedCIDRv6)
		if err != nil {
			return err
		}

		// In case user has specified the daemon flag --fixed-cidr-v6 and the passed network has
		// at least 48 host bits, we need to guarantee the current behavior where the containers'
		// IPv6 addresses will be constructed based on the containers' interface MAC address.
		// We do so by telling libnetwork to defer the IPv6 address allocation for the endpoints
		// on this network until after the driver has created the endpoint and returned the
		// constructed address. Libnetwork will then reserve this address with the ipam driver.
		ones, _ := fCIDRv6.Mask.Size()
		deferIPv6Alloc = ones <= 80

		ipamV6Conf = &libnetwork.IpamConf{
			AuxAddresses:  make(map[string]string),
			PreferredPool: fCIDRv6.String(),
		}

		// In case the --fixed-cidr-v6 is specified and the current docker0 bridge IPv6
		// address belongs to the same network, we need to inform libnetwork about it, so
		// that it can be reserved with IPAM and it will not be given away to somebody else
		for _, nw6 := range nw6List {
			if fCIDRv6.Contains(nw6.IP) {
				ipamV6Conf.Gateway = nw6.IP.String()
				break
			}
		}
	}

	if config.BridgeConfig.DefaultGatewayIPv6 != nil {
		if ipamV6Conf == nil {
			ipamV6Conf = &libnetwork.IpamConf{AuxAddresses: make(map[string]string)}
		}
		ipamV6Conf.AuxAddresses["DefaultGatewayIPv6"] = config.BridgeConfig.DefaultGatewayIPv6.String()
	}

	v4Conf := []*libnetwork.IpamConf{ipamV4Conf}
	v6Conf := []*libnetwork.IpamConf{}
	if ipamV6Conf != nil {
		v6Conf = append(v6Conf, ipamV6Conf)
	}
	// Initialize default network on "bridge" with the same name
	_, err = controller.NewNetwork("bridge", "bridge", "",
		libnetwork.NetworkOptionEnableIPv6(config.BridgeConfig.EnableIPv6),
		libnetwork.NetworkOptionDriverOpts(netOption),
		libnetwork.NetworkOptionIpam("default", "", v4Conf, v6Conf, nil),
		libnetwork.NetworkOptionDeferIPv6Alloc(deferIPv6Alloc))
	if err != nil {
		return fmt.Errorf("Error creating default \"bridge\" network: %v", err)
	}
	return nil
}

// Remove default bridge interface if present (--bridge=none use case)
func removeDefaultBridgeInterface() {
	if lnk, err := netlink.LinkByName(bridge.DefaultBridgeName); err == nil {
		if err := netlink.LinkDel(lnk); err != nil {
			logrus.Warnf("Failed to remove bridge interface (%s): %v", bridge.DefaultBridgeName, err)
		}
	}
}

func setupInitLayer(idMapping idtools.IdentityMapping) func(containerfs.ContainerFS) error {
	return func(initPath containerfs.ContainerFS) error {
		return initlayer.Setup(initPath, idMapping.RootPair())
	}
}

// Parse the remapped root (user namespace) option, which can be one of:
//
// - username            - valid username from /etc/passwd
// - username:groupname  - valid username; valid groupname from /etc/group
// - uid                 - 32-bit unsigned int valid Linux UID value
// - uid:gid             - uid value; 32-bit unsigned int Linux GID value
//
// If no groupname is specified, and a username is specified, an attempt
// will be made to lookup a gid for that username as a groupname
//
// If names are used, they are verified to exist in passwd/group
func parseRemappedRoot(usergrp string) (string, string, error) {

	var (
		userID, groupID     int
		username, groupname string
	)

	idparts := strings.Split(usergrp, ":")
	if len(idparts) > 2 {
		return "", "", fmt.Errorf("Invalid user/group specification in --userns-remap: %q", usergrp)
	}

	if uid, err := strconv.ParseInt(idparts[0], 10, 32); err == nil {
		// must be a uid; take it as valid
		userID = int(uid)
		luser, err := idtools.LookupUID(userID)
		if err != nil {
			return "", "", fmt.Errorf("Uid %d has no entry in /etc/passwd: %v", userID, err)
		}
		username = luser.Name
		if len(idparts) == 1 {
			// if the uid was numeric and no gid was specified, take the uid as the gid
			groupID = userID
			lgrp, err := idtools.LookupGID(groupID)
			if err != nil {
				return "", "", fmt.Errorf("Gid %d has no entry in /etc/group: %v", groupID, err)
			}
			groupname = lgrp.Name
		}
	} else {
		lookupName := idparts[0]
		// special case: if the user specified "default", they want Docker to create or
		// use (after creation) the "dockremap" user/group for root remapping
		if lookupName == defaultIDSpecifier {
			lookupName = defaultRemappedID
		}
		luser, err := idtools.LookupUser(lookupName)
		if err != nil && idparts[0] != defaultIDSpecifier {
			// error if the name requested isn't the special "dockremap" ID
			return "", "", fmt.Errorf("Error during uid lookup for %q: %v", lookupName, err)
		} else if err != nil {
			// special case-- if the username == "default", then we have been asked
			// to create a new entry pair in /etc/{passwd,group} for which the /etc/sub{uid,gid}
			// ranges will be used for the user and group mappings in user namespaced containers
			_, _, err := idtools.AddNamespaceRangesUser(defaultRemappedID)
			if err == nil {
				return defaultRemappedID, defaultRemappedID, nil
			}
			return "", "", fmt.Errorf("Error during %q user creation: %v", defaultRemappedID, err)
		}
		username = luser.Name
		if len(idparts) == 1 {
			// we only have a string username, and no group specified; look up gid from username as group
			group, err := idtools.LookupGroup(lookupName)
			if err != nil {
				return "", "", fmt.Errorf("Error during gid lookup for %q: %v", lookupName, err)
			}
			groupname = group.Name
		}
	}

	if len(idparts) == 2 {
		// groupname or gid is separately specified and must be resolved
		// to an unsigned 32-bit gid
		if gid, err := strconv.ParseInt(idparts[1], 10, 32); err == nil {
			// must be a gid, take it as valid
			groupID = int(gid)
			lgrp, err := idtools.LookupGID(groupID)
			if err != nil {
				return "", "", fmt.Errorf("Gid %d has no entry in /etc/passwd: %v", groupID, err)
			}
			groupname = lgrp.Name
		} else {
			// not a number; attempt a lookup
			if _, err := idtools.LookupGroup(idparts[1]); err != nil {
				return "", "", fmt.Errorf("Error during groupname lookup for %q: %v", idparts[1], err)
			}
			groupname = idparts[1]
		}
	}
	return username, groupname, nil
}

func setupRemappedRoot(config *config.Config) (idtools.IdentityMapping, error) {
	if runtime.GOOS != "linux" && config.RemappedRoot != "" {
		return idtools.IdentityMapping{}, fmt.Errorf("User namespaces are only supported on Linux")
	}

	// if the daemon was started with remapped root option, parse
	// the config option to the int uid,gid values
	if config.RemappedRoot != "" {
		username, groupname, err := parseRemappedRoot(config.RemappedRoot)
		if err != nil {
			return idtools.IdentityMapping{}, err
		}
		if username == "root" {
			// Cannot setup user namespaces with a 1-to-1 mapping; "--root=0:0" is a no-op
			// effectively
			logrus.Warn("User namespaces: root cannot be remapped with itself; user namespaces are OFF")
			return idtools.IdentityMapping{}, nil
		}
		logrus.Infof("User namespaces: ID ranges will be mapped to subuid/subgid ranges of: %s", username)
		// update remapped root setting now that we have resolved them to actual names
		config.RemappedRoot = fmt.Sprintf("%s:%s", username, groupname)

		mappings, err := idtools.LoadIdentityMapping(username)
		if err != nil {
			return idtools.IdentityMapping{}, errors.Wrap(err, "Can't create ID mappings")
		}
		return mappings, nil
	}
	return idtools.IdentityMapping{}, nil
}

func setupDaemonRoot(config *config.Config, rootDir string, remappedRoot idtools.Identity) error {
	config.Root = rootDir
	// the docker root metadata directory needs to have execute permissions for all users (g+x,o+x)
	// so that syscalls executing as non-root, operating on subdirectories of the graph root
	// (e.g. mounted layers of a container) can traverse this path.
	// The user namespace support will create subdirectories for the remapped root host uid:gid
	// pair owned by that same uid:gid pair for proper write access to those needed metadata and
	// layer content subtrees.
	if _, err := os.Stat(rootDir); err == nil {
		// root current exists; verify the access bits are correct by setting them
		if err = os.Chmod(rootDir, 0711); err != nil {
			return err
		}
	} else if os.IsNotExist(err) {
		// no root exists yet, create it 0711 with root:root ownership
		if err := os.MkdirAll(rootDir, 0711); err != nil {
			return err
		}
	}

	id := idtools.Identity{UID: idtools.CurrentIdentity().UID, GID: remappedRoot.GID}
	// First make sure the current root dir has the correct perms.
	if err := idtools.MkdirAllAndChown(config.Root, 0710, id); err != nil {
		return errors.Wrapf(err, "could not create or set daemon root permissions: %s", config.Root)
	}

	// if user namespaces are enabled we will create a subtree underneath the specified root
	// with any/all specified remapped root uid/gid options on the daemon creating
	// a new subdirectory with ownership set to the remapped uid/gid (so as to allow
	// `chdir()` to work for containers namespaced to that uid/gid)
	if config.RemappedRoot != "" {
		config.Root = filepath.Join(rootDir, fmt.Sprintf("%d.%d", remappedRoot.UID, remappedRoot.GID))
		logrus.Debugf("Creating user namespaced daemon root: %s", config.Root)
		// Create the root directory if it doesn't exist
		if err := idtools.MkdirAllAndChown(config.Root, 0710, id); err != nil {
			return fmt.Errorf("Cannot create daemon root: %s: %v", config.Root, err)
		}
		// we also need to verify that any pre-existing directories in the path to
		// the graphroot won't block access to remapped root--if any pre-existing directory
		// has strict permissions that don't allow "x", container start will fail, so
		// better to warn and fail now
		dirPath := config.Root
		for {
			dirPath = filepath.Dir(dirPath)
			if dirPath == "/" {
				break
			}
			if !idtools.CanAccess(dirPath, remappedRoot) {
				return fmt.Errorf("a subdirectory in your graphroot path (%s) restricts access to the remapped root uid/gid; please fix by allowing 'o+x' permissions on existing directories", config.Root)
			}
		}
	}

	if err := setupDaemonRootPropagation(config); err != nil {
		logrus.WithError(err).WithField("dir", config.Root).Warn("Error while setting daemon root propagation, this is not generally critical but may cause some functionality to not work or fallback to less desirable behavior")
	}
	return nil
}

func setupDaemonRootPropagation(cfg *config.Config) error {
	rootParentMount, mountOptions, err := getSourceMount(cfg.Root)
	if err != nil {
		return errors.Wrap(err, "error getting daemon root's parent mount")
	}

	var cleanupOldFile bool
	cleanupFile := getUnmountOnShutdownPath(cfg)
	defer func() {
		if !cleanupOldFile {
			return
		}
		if err := os.Remove(cleanupFile); err != nil && !os.IsNotExist(err) {
			logrus.WithError(err).WithField("file", cleanupFile).Warn("could not clean up old root propagation unmount file")
		}
	}()

	if hasMountInfoOption(mountOptions, sharedPropagationOption, slavePropagationOption) {
		cleanupOldFile = true
		return nil
	}

	if err := mount.MakeShared(cfg.Root); err != nil {
		return errors.Wrap(err, "could not setup daemon root propagation to shared")
	}

	// check the case where this may have already been a mount to itself.
	// If so then the daemon only performed a remount and should not try to unmount this later.
	if rootParentMount == cfg.Root {
		cleanupOldFile = true
		return nil
	}

	if err := os.MkdirAll(filepath.Dir(cleanupFile), 0700); err != nil {
		return errors.Wrap(err, "error creating dir to store mount cleanup file")
	}

	if err := os.WriteFile(cleanupFile, nil, 0600); err != nil {
		return errors.Wrap(err, "error writing file to signal mount cleanup on shutdown")
	}
	return nil
}

// getUnmountOnShutdownPath generates the path to used when writing the file that signals to the daemon that on shutdown
// the daemon root should be unmounted.
func getUnmountOnShutdownPath(config *config.Config) string {
	return filepath.Join(config.ExecRoot, "unmount-on-shutdown")
}

// registerLinks writes the links to a file.
func (daemon *Daemon) registerLinks(container *container.Container, hostConfig *containertypes.HostConfig) error {
	if hostConfig == nil || hostConfig.NetworkMode.IsUserDefined() {
		return nil
	}

	for _, l := range hostConfig.Links {
		name, alias, err := opts.ParseLink(l)
		if err != nil {
			return err
		}
		child, err := daemon.GetContainer(name)
		if err != nil {
			if errdefs.IsNotFound(err) {
				// Trying to link to a non-existing container is not valid, and
				// should return an "invalid parameter" error. Returning a "not
				// found" error here would make the client report the container's
				// image could not be found (see moby/moby#39823)
				err = errdefs.InvalidParameter(err)
			}
			return errors.Wrapf(err, "could not get container for %s", name)
		}
		for child.HostConfig.NetworkMode.IsContainer() {
			parts := strings.SplitN(string(child.HostConfig.NetworkMode), ":", 2)
			child, err = daemon.GetContainer(parts[1])
			if err != nil {
				if errdefs.IsNotFound(err) {
					// Trying to link to a non-existing container is not valid, and
					// should return an "invalid parameter" error. Returning a "not
					// found" error here would make the client report the container's
					// image could not be found (see moby/moby#39823)
					err = errdefs.InvalidParameter(err)
				}
				return errors.Wrapf(err, "Could not get container for %s", parts[1])
			}
		}
		if child.HostConfig.NetworkMode.IsHost() {
			return runconfig.ErrConflictHostNetworkAndLinks
		}
		if err := daemon.registerLink(container, child, alias); err != nil {
			return err
		}
	}

	// After we load all the links into the daemon
	// set them to nil on the hostconfig
	_, err := container.WriteHostConfig()
	return err
}

// conditionalMountOnStart is a platform specific helper function during the
// container start to call mount.
func (daemon *Daemon) conditionalMountOnStart(container *container.Container) error {
	return daemon.Mount(container)
}

// conditionalUnmountOnCleanup is a platform specific helper function called
// during the cleanup of a container to unmount.
func (daemon *Daemon) conditionalUnmountOnCleanup(container *container.Container) error {
	return daemon.Unmount(container)
}

func copyBlkioEntry(entries []*statsV1.BlkIOEntry) []types.BlkioStatEntry {
	out := make([]types.BlkioStatEntry, len(entries))
	for i, re := range entries {
		out[i] = types.BlkioStatEntry{
			Major: re.Major,
			Minor: re.Minor,
			Op:    re.Op,
			Value: re.Value,
		}
	}
	return out
}

func (daemon *Daemon) stats(c *container.Container) (*types.StatsJSON, error) {
	if !c.IsRunning() {
		return nil, errNotRunning(c.ID)
	}
	cs, err := daemon.containerd.Stats(context.Background(), c.ID)
	if err != nil {
		if strings.Contains(err.Error(), "container not found") {
			return nil, containerNotFound(c.ID)
		}
		return nil, err
	}
	s := &types.StatsJSON{}
	s.Read = cs.Read
	stats := cs.Metrics
	switch t := stats.(type) {
	case *statsV1.Metrics:
		return daemon.statsV1(s, t)
	case *statsV2.Metrics:
		return daemon.statsV2(s, t)
	default:
		return nil, errors.Errorf("unexpected type of metrics %+v", t)
	}
}

func (daemon *Daemon) statsV1(s *types.StatsJSON, stats *statsV1.Metrics) (*types.StatsJSON, error) {
	if stats.Blkio != nil {
		s.BlkioStats = types.BlkioStats{
			IoServiceBytesRecursive: copyBlkioEntry(stats.Blkio.IoServiceBytesRecursive),
			IoServicedRecursive:     copyBlkioEntry(stats.Blkio.IoServicedRecursive),
			IoQueuedRecursive:       copyBlkioEntry(stats.Blkio.IoQueuedRecursive),
			IoServiceTimeRecursive:  copyBlkioEntry(stats.Blkio.IoServiceTimeRecursive),
			IoWaitTimeRecursive:     copyBlkioEntry(stats.Blkio.IoWaitTimeRecursive),
			IoMergedRecursive:       copyBlkioEntry(stats.Blkio.IoMergedRecursive),
			IoTimeRecursive:         copyBlkioEntry(stats.Blkio.IoTimeRecursive),
			SectorsRecursive:        copyBlkioEntry(stats.Blkio.SectorsRecursive),
		}
	}
	if stats.CPU != nil {
		s.CPUStats = types.CPUStats{
			CPUUsage: types.CPUUsage{
				TotalUsage:        stats.CPU.Usage.Total,
				PercpuUsage:       stats.CPU.Usage.PerCPU,
				UsageInKernelmode: stats.CPU.Usage.Kernel,
				UsageInUsermode:   stats.CPU.Usage.User,
			},
			ThrottlingData: types.ThrottlingData{
				Periods:          stats.CPU.Throttling.Periods,
				ThrottledPeriods: stats.CPU.Throttling.ThrottledPeriods,
				ThrottledTime:    stats.CPU.Throttling.ThrottledTime,
			},
		}
	}

	if stats.Memory != nil {
		raw := map[string]uint64{
			"cache":                     stats.Memory.Cache,
			"rss":                       stats.Memory.RSS,
			"rss_huge":                  stats.Memory.RSSHuge,
			"mapped_file":               stats.Memory.MappedFile,
			"dirty":                     stats.Memory.Dirty,
			"writeback":                 stats.Memory.Writeback,
			"pgpgin":                    stats.Memory.PgPgIn,
			"pgpgout":                   stats.Memory.PgPgOut,
			"pgfault":                   stats.Memory.PgFault,
			"pgmajfault":                stats.Memory.PgMajFault,
			"inactive_anon":             stats.Memory.InactiveAnon,
			"active_anon":               stats.Memory.ActiveAnon,
			"inactive_file":             stats.Memory.InactiveFile,
			"active_file":               stats.Memory.ActiveFile,
			"unevictable":               stats.Memory.Unevictable,
			"hierarchical_memory_limit": stats.Memory.HierarchicalMemoryLimit,
			"hierarchical_memsw_limit":  stats.Memory.HierarchicalSwapLimit,
			"total_cache":               stats.Memory.TotalCache,
			"total_rss":                 stats.Memory.TotalRSS,
			"total_rss_huge":            stats.Memory.TotalRSSHuge,
			"total_mapped_file":         stats.Memory.TotalMappedFile,
			"total_dirty":               stats.Memory.TotalDirty,
			"total_writeback":           stats.Memory.TotalWriteback,
			"total_pgpgin":              stats.Memory.TotalPgPgIn,
			"total_pgpgout":             stats.Memory.TotalPgPgOut,
			"total_pgfault":             stats.Memory.TotalPgFault,
			"total_pgmajfault":          stats.Memory.TotalPgMajFault,
			"total_inactive_anon":       stats.Memory.TotalInactiveAnon,
			"total_active_anon":         stats.Memory.TotalActiveAnon,
			"total_inactive_file":       stats.Memory.TotalInactiveFile,
			"total_active_file":         stats.Memory.TotalActiveFile,
			"total_unevictable":         stats.Memory.TotalUnevictable,
		}
		if stats.Memory.Usage != nil {
			s.MemoryStats = types.MemoryStats{
				Stats:    raw,
				Usage:    stats.Memory.Usage.Usage,
				MaxUsage: stats.Memory.Usage.Max,
				Limit:    stats.Memory.Usage.Limit,
				Failcnt:  stats.Memory.Usage.Failcnt,
			}
		} else {
			s.MemoryStats = types.MemoryStats{
				Stats: raw,
			}
		}

		// if the container does not set memory limit, use the machineMemory
		if s.MemoryStats.Limit > daemon.machineMemory && daemon.machineMemory > 0 {
			s.MemoryStats.Limit = daemon.machineMemory
		}
	}

	if stats.Pids != nil {
		s.PidsStats = types.PidsStats{
			Current: stats.Pids.Current,
			Limit:   stats.Pids.Limit,
		}
	}

	return s, nil
}

func (daemon *Daemon) statsV2(s *types.StatsJSON, stats *statsV2.Metrics) (*types.StatsJSON, error) {
	if stats.Io != nil {
		var isbr []types.BlkioStatEntry
		for _, re := range stats.Io.Usage {
			isbr = append(isbr,
				types.BlkioStatEntry{
					Major: re.Major,
					Minor: re.Minor,
					Op:    "read",
					Value: re.Rbytes,
				},
				types.BlkioStatEntry{
					Major: re.Major,
					Minor: re.Minor,
					Op:    "write",
					Value: re.Wbytes,
				},
			)
		}
		s.BlkioStats = types.BlkioStats{
			IoServiceBytesRecursive: isbr,
			// Other fields are unsupported
		}
	}

	if stats.CPU != nil {
		s.CPUStats = types.CPUStats{
			CPUUsage: types.CPUUsage{
				TotalUsage: stats.CPU.UsageUsec * 1000,
				// PercpuUsage is not supported
				UsageInKernelmode: stats.CPU.SystemUsec * 1000,
				UsageInUsermode:   stats.CPU.UserUsec * 1000,
			},
			ThrottlingData: types.ThrottlingData{
				Periods:          stats.CPU.NrPeriods,
				ThrottledPeriods: stats.CPU.NrThrottled,
				ThrottledTime:    stats.CPU.ThrottledUsec * 1000,
			},
		}
	}

	if stats.Memory != nil {
		s.MemoryStats = types.MemoryStats{
			// Stats is not compatible with v1
			Stats: map[string]uint64{
				"anon":                   stats.Memory.Anon,
				"file":                   stats.Memory.File,
				"kernel_stack":           stats.Memory.KernelStack,
				"slab":                   stats.Memory.Slab,
				"sock":                   stats.Memory.Sock,
				"shmem":                  stats.Memory.Shmem,
				"file_mapped":            stats.Memory.FileMapped,
				"file_dirty":             stats.Memory.FileDirty,
				"file_writeback":         stats.Memory.FileWriteback,
				"anon_thp":               stats.Memory.AnonThp,
				"inactive_anon":          stats.Memory.InactiveAnon,
				"active_anon":            stats.Memory.ActiveAnon,
				"inactive_file":          stats.Memory.InactiveFile,
				"active_file":            stats.Memory.ActiveFile,
				"unevictable":            stats.Memory.Unevictable,
				"slab_reclaimable":       stats.Memory.SlabReclaimable,
				"slab_unreclaimable":     stats.Memory.SlabUnreclaimable,
				"pgfault":                stats.Memory.Pgfault,
				"pgmajfault":             stats.Memory.Pgmajfault,
				"workingset_refault":     stats.Memory.WorkingsetRefault,
				"workingset_activate":    stats.Memory.WorkingsetActivate,
				"workingset_nodereclaim": stats.Memory.WorkingsetNodereclaim,
				"pgrefill":               stats.Memory.Pgrefill,
				"pgscan":                 stats.Memory.Pgscan,
				"pgsteal":                stats.Memory.Pgsteal,
				"pgactivate":             stats.Memory.Pgactivate,
				"pgdeactivate":           stats.Memory.Pgdeactivate,
				"pglazyfree":             stats.Memory.Pglazyfree,
				"pglazyfreed":            stats.Memory.Pglazyfreed,
				"thp_fault_alloc":        stats.Memory.ThpFaultAlloc,
				"thp_collapse_alloc":     stats.Memory.ThpCollapseAlloc,
			},
			Usage: stats.Memory.Usage,
			// MaxUsage is not supported
			Limit: stats.Memory.UsageLimit,
		}
		// if the container does not set memory limit, use the machineMemory
		if s.MemoryStats.Limit > daemon.machineMemory && daemon.machineMemory > 0 {
			s.MemoryStats.Limit = daemon.machineMemory
		}
		if stats.MemoryEvents != nil {
			// Failcnt is set to the "oom" field of the "memory.events" file.
			// See https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html
			s.MemoryStats.Failcnt = stats.MemoryEvents.Oom
		}
	}

	if stats.Pids != nil {
		s.PidsStats = types.PidsStats{
			Current: stats.Pids.Current,
			Limit:   stats.Pids.Limit,
		}
	}

	return s, nil
}

// setDefaultIsolation determines the default isolation mode for the
// daemon to run in. This is only applicable on Windows
func (daemon *Daemon) setDefaultIsolation() error {
	return nil
}

// setupDaemonProcess sets various settings for the daemon's process
func setupDaemonProcess(config *config.Config) error {
	// setup the daemons oom_score_adj
	if err := setupOOMScoreAdj(config.OOMScoreAdjust); err != nil {
		return err
	}
	if err := setMayDetachMounts(); err != nil {
		logrus.WithError(err).Warn("Could not set may_detach_mounts kernel parameter")
	}
	return nil
}

// This is used to allow removal of mountpoints that may be mounted in other
// namespaces on RHEL based kernels starting from RHEL 7.4.
// Without this setting, removals on these RHEL based kernels may fail with
// "device or resource busy".
// This setting is not available in upstream kernels as it is not configurable,
// but has been in the upstream kernels since 3.15.
func setMayDetachMounts() error {
	f, err := os.OpenFile("/proc/sys/fs/may_detach_mounts", os.O_WRONLY, 0)
	if err != nil {
		if os.IsNotExist(err) {
			return nil
		}
		return errors.Wrap(err, "error opening may_detach_mounts kernel config file")
	}
	defer f.Close()

	_, err = f.WriteString("1")
	if os.IsPermission(err) {
		// Setting may_detach_mounts does not work in an
		// unprivileged container. Ignore the error, but log
		// it if we appear not to be in that situation.
		if !userns.RunningInUserNS() {
			logrus.Debugf("Permission denied writing %q to /proc/sys/fs/may_detach_mounts", "1")
		}
		return nil
	}
	return err
}

func setupOOMScoreAdj(score int) error {
	if score == 0 {
		return nil
	}
	f, err := os.OpenFile("/proc/self/oom_score_adj", os.O_WRONLY, 0)
	if err != nil {
		return err
	}
	defer f.Close()
	stringScore := strconv.Itoa(score)
	_, err = f.WriteString(stringScore)
	if os.IsPermission(err) {
		// Setting oom_score_adj does not work in an
		// unprivileged container. Ignore the error, but log
		// it if we appear not to be in that situation.
		if !userns.RunningInUserNS() {
			logrus.Debugf("Permission denied writing %q to /proc/self/oom_score_adj", stringScore)
		}
		return nil
	}

	return err
}

func (daemon *Daemon) initCPURtController(mnt, path string) error {
	if path == "/" || path == "." {
		return nil
	}

	// Recursively create cgroup to ensure that the system and all parent cgroups have values set
	// for the period and runtime as this limits what the children can be set to.
	if err := daemon.initCPURtController(mnt, filepath.Dir(path)); err != nil {
		return err
	}

	path = filepath.Join(mnt, path)
	if err := os.MkdirAll(path, 0755); err != nil {
		return err
	}
	if err := maybeCreateCPURealTimeFile(daemon.configStore.CPURealtimePeriod, "cpu.rt_period_us", path); err != nil {
		return err
	}
	return maybeCreateCPURealTimeFile(daemon.configStore.CPURealtimeRuntime, "cpu.rt_runtime_us", path)
}

func maybeCreateCPURealTimeFile(configValue int64, file string, path string) error {
	if configValue == 0 {
		return nil
	}
	return os.WriteFile(filepath.Join(path, file), []byte(strconv.FormatInt(configValue, 10)), 0700)
}

func (daemon *Daemon) setupSeccompProfile() error {
	switch profile := daemon.configStore.SeccompProfile; profile {
	case "", config.SeccompProfileDefault:
		daemon.seccompProfilePath = config.SeccompProfileDefault
	case config.SeccompProfileUnconfined:
		daemon.seccompProfilePath = config.SeccompProfileUnconfined
	default:
		daemon.seccompProfilePath = profile
		b, err := os.ReadFile(profile)
		if err != nil {
			return fmt.Errorf("opening seccomp profile (%s) failed: %v", profile, err)
		}
		daemon.seccompProfile = b
	}
	return nil
}

func getSysInfo(daemon *Daemon) *sysinfo.SysInfo {
	var siOpts []sysinfo.Opt
	if daemon.getCgroupDriver() == cgroupSystemdDriver {
		if euid := os.Getenv("ROOTLESSKIT_PARENT_EUID"); euid != "" {
			siOpts = append(siOpts, sysinfo.WithCgroup2GroupPath("/user.slice/user-"+euid+".slice"))
		}
	}
	return sysinfo.New(siOpts...)
}

func (daemon *Daemon) initLibcontainerd(ctx context.Context) error {
	var err error
	daemon.containerd, err = remote.NewClient(
		ctx,
		daemon.containerdCli,
		filepath.Join(daemon.configStore.ExecRoot, "containerd"),
		daemon.configStore.ContainerdNamespace,
		daemon,
	)
	return err
}

func recursiveUnmount(target string) error {
	return mount.RecursiveUnmount(target)
}

Not introduced in this PR, but this looks somewhat odd in a `verifyXX` function; if I see it correctly, this may (due to `hostConfig` being passed by reference) be mutating the config, both on _create_ and _start_ (and possible other locations that call `verifyContainerSettings()`).

Possibly the intent was to bake the config into the container's config, but if it's called in multiple locations, it may actually have become mutable 🤔 