package sysinfo
import (
"context"
"fmt"
"os"
"path"
"strconv"
"strings"
"sync"
"github.com/containerd/cgroups/v3"
"github.com/containerd/cgroups/v3/cgroup1"
"github.com/containerd/containerd/v2/pkg/seccomp"
"github.com/containerd/log"
"github.com/moby/sys/mountinfo"
)
var (
readMountinfoOnce sync.Once
readMountinfoErr error
cgroupMountinfo []*mountinfo.Info
)
// readCgroupMountinfo returns a list of cgroup v1 mounts (i.e. the ones
// with fstype of "cgroup") for the current running process.
//
// The results are cached (to avoid re-reading mountinfo which is relatively
// expensive), so it is assumed that cgroup mounts are not being changed.
func readCgroupMountinfo() ([]*mountinfo.Info, error) {
readMountinfoOnce.Do(func() {
cgroupMountinfo, readMountinfoErr = mountinfo.GetMounts(
mountinfo.FSTypeFilter("cgroup"),
)
})
return cgroupMountinfo, readMountinfoErr
}
func findCgroupV1Mountpoints() (map[string]string, error) {
mounts, err := readCgroupMountinfo()
if err != nil {
return nil, err
}
allSubsystems, err := cgroup1.ParseCgroupFile("/proc/self/cgroup")
if err != nil {
return nil, fmt.Errorf("Failed to parse cgroup information: %v", err)
}
allMap := make(map[string]bool)
for s := range allSubsystems {
allMap[s] = false
}
mps := make(map[string]string)
for _, mi := range mounts {
for opt := range strings.SplitSeq(mi.VFSOptions, ",") {
seen, known := allMap[opt]
if known && !seen {
allMap[opt] = true
mps[strings.TrimPrefix(opt, "name=")] = mi.Mountpoint
}
}
if len(mps) >= len(allMap) {
break
}
}
return mps, nil
}
type infoCollector func(info *SysInfo)
// WithCgroup2GroupPath specifies the cgroup v2 group path to inspect availability
// of the controllers.
//
// WithCgroup2GroupPath is expected to be used for rootless mode with systemd driver.
//
// e.g. g = "/user.slice/user-1000.slice/user@1000.service"
func WithCgroup2GroupPath(g string) Opt {
return func(o *SysInfo) {
if p := path.Clean(g); p != "" {
o.cg2GroupPath = p
}
}
}
// New returns a new SysInfo, using the filesystem to detect which features
// the kernel supports.
func New(options ...Opt) *SysInfo {
if cgroups.Mode() == cgroups.Unified {
return newV2(options...)
}
return newV1()
}
func newV1() *SysInfo {
var (
err error
sysInfo = &SysInfo{}
)
ops := []infoCollector{
applyNetworkingInfo,
applyAppArmorInfo,
applySeccompInfo,
applyCgroupNsInfo,
applyTimeNsInfo,
}
sysInfo.cgMounts, err = findCgroupV1Mountpoints()
if err != nil {
log.G(context.TODO()).Warn(err)
} else {
ops = append(ops,
applyMemoryCgroupInfo,
applyCPUCgroupInfo,
applyBlkioCgroupInfo,
applyCPUSetCgroupInfo,
applyPIDSCgroupInfo,
applyDevicesCgroupInfo,
)
}
for _, o := range ops {
o(sysInfo)
}
return sysInfo
}
// applyMemoryCgroupInfo adds the memory cgroup controller information to the info.
func applyMemoryCgroupInfo(info *SysInfo) {
mountPoint, ok := info.cgMounts["memory"]
if !ok {
info.Warnings = append(info.Warnings, "Your kernel does not support cgroup memory limit")
return
}
info.MemoryLimit = ok
info.SwapLimit = cgroupEnabled(mountPoint, "memory.memsw.limit_in_bytes")
if !info.SwapLimit {
info.Warnings = append(info.Warnings, "Your kernel does not support swap memory limit")
}
info.MemoryReservation = cgroupEnabled(mountPoint, "memory.soft_limit_in_bytes")
if !info.MemoryReservation {
info.Warnings = append(info.Warnings, "Your kernel does not support memory reservation")
}
info.OomKillDisable = cgroupEnabled(mountPoint, "memory.oom_control")
if !info.OomKillDisable {
info.Warnings = append(info.Warnings, "Your kernel does not support oom control")
}
info.MemorySwappiness = cgroupEnabled(mountPoint, "memory.swappiness")
if !info.MemorySwappiness {
info.Warnings = append(info.Warnings, "Your kernel does not support memory swappiness")
}
}
// applyCPUCgroupInfo adds the cpu cgroup controller information to the info.
func applyCPUCgroupInfo(info *SysInfo) {
mountPoint, ok := info.cgMounts["cpu"]
if !ok {
info.Warnings = append(info.Warnings, "Unable to find cpu cgroup in mounts")
return
}
info.CPUShares = cgroupEnabled(mountPoint, "cpu.shares")
if !info.CPUShares {
info.Warnings = append(info.Warnings, "Your kernel does not support CPU shares")
}
info.CPUCfs = cgroupEnabled(mountPoint, "cpu.cfs_quota_us")
if !info.CPUCfs {
info.Warnings = append(info.Warnings, "Your kernel does not support CPU CFS scheduler")
}
info.CPURealtime = cgroupEnabled(mountPoint, "cpu.rt_period_us")
if !info.CPURealtime {
info.Warnings = append(info.Warnings, "Your kernel does not support CPU realtime scheduler")
}
}
// applyBlkioCgroupInfo adds the blkio cgroup controller information to the info.
func applyBlkioCgroupInfo(info *SysInfo) {
mountPoint, ok := info.cgMounts["blkio"]
if !ok {
info.Warnings = append(info.Warnings, "Unable to find blkio cgroup in mounts")
return
}
info.BlkioWeight = cgroupEnabled(mountPoint, "blkio.weight")
if !info.BlkioWeight {
info.Warnings = append(info.Warnings, "Your kernel does not support cgroup blkio weight")
}
info.BlkioWeightDevice = cgroupEnabled(mountPoint, "blkio.weight_device")
if !info.BlkioWeightDevice {
info.Warnings = append(info.Warnings, "Your kernel does not support cgroup blkio weight_device")
}
info.BlkioReadBpsDevice = cgroupEnabled(mountPoint, "blkio.throttle.read_bps_device")
if !info.BlkioReadBpsDevice {
info.Warnings = append(info.Warnings, "Your kernel does not support cgroup blkio throttle.read_bps_device")
}
info.BlkioWriteBpsDevice = cgroupEnabled(mountPoint, "blkio.throttle.write_bps_device")
if !info.BlkioWriteBpsDevice {
info.Warnings = append(info.Warnings, "Your kernel does not support cgroup blkio throttle.write_bps_device")
}
info.BlkioReadIOpsDevice = cgroupEnabled(mountPoint, "blkio.throttle.read_iops_device")
if !info.BlkioReadIOpsDevice {
info.Warnings = append(info.Warnings, "Your kernel does not support cgroup blkio throttle.read_iops_device")
}
info.BlkioWriteIOpsDevice = cgroupEnabled(mountPoint, "blkio.throttle.write_iops_device")
if !info.BlkioWriteIOpsDevice {
info.Warnings = append(info.Warnings, "Your kernel does not support cgroup blkio throttle.write_iops_device")
}
}
// applyCPUSetCgroupInfo adds the cpuset cgroup controller information to the info.
func applyCPUSetCgroupInfo(info *SysInfo) {
mountPoint, ok := info.cgMounts["cpuset"]
if !ok {
info.Warnings = append(info.Warnings, "Unable to find cpuset cgroup in mounts")
return
}
info.Cpuset = ok
var err error
cpus, err := os.ReadFile(path.Join(mountPoint, "cpuset.cpus"))
if err != nil {
return
}
info.Cpus = strings.TrimSpace(string(cpus))
cpuSets, err := parseUintList(info.Cpus, 0)
if err != nil {
info.Warnings = append(info.Warnings, "Unable to parse cpuset cpus: "+err.Error())
return
}
info.CPUSets = cpuSets
mems, err := os.ReadFile(path.Join(mountPoint, "cpuset.mems"))
if err != nil {
return
}
info.Mems = strings.TrimSpace(string(mems))
memSets, err := parseUintList(info.Cpus, 0)
if err != nil {
info.Warnings = append(info.Warnings, "Unable to parse cpuset mems: "+err.Error())
return
}
info.MemSets = memSets
}
// applyPIDSCgroupInfo adds whether the pids cgroup controller is available to the info.
func applyPIDSCgroupInfo(info *SysInfo) {
_, ok := info.cgMounts["pids"]
if !ok {
info.Warnings = append(info.Warnings, "Unable to find pids cgroup in mounts")
return
}
info.PidsLimit = true
}
// applyDevicesCgroupInfo adds whether the devices cgroup controller is available to the info.
func applyDevicesCgroupInfo(info *SysInfo) {
_, ok := info.cgMounts["devices"]
info.CgroupDevicesEnabled = ok
}
// applyNetworkingInfo adds networking information to the info.
func applyNetworkingInfo(info *SysInfo) {
info.IPv4ForwardingDisabled = !readProcBool("/proc/sys/net/ipv4/ip_forward")
}
// applyAppArmorInfo adds whether AppArmor is enabled to the info.
func applyAppArmorInfo(info *SysInfo) {
info.AppArmor = apparmorSupported()
}
// applyCgroupNsInfo adds whether cgroupns is enabled to the info.
func applyCgroupNsInfo(info *SysInfo) {
info.CgroupNamespaces = cgroupnsSupported()
}
// applyTimeNsInfo adds whether time namespaces are supported to the info.
func applyTimeNsInfo(info *SysInfo) {
info.TimeNamespaces = timeNsSupported()
}
// applySeccompInfo checks if Seccomp is supported, via CONFIG_SECCOMP.
func applySeccompInfo(info *SysInfo) {
info.Seccomp = seccomp.IsEnabled()
}
// apparmorSupported adds whether AppArmor is enabled.
func apparmorSupported() bool {
if _, err := os.Stat("/sys/kernel/security/apparmor"); !os.IsNotExist(err) {
if _, err := os.ReadFile("/sys/kernel/security/apparmor/profiles"); err == nil {
return true
}
}
return false
}
// cgroupnsSupported adds whether cgroup namespaces are supported.
func cgroupnsSupported() bool {
if _, err := os.Stat("/proc/self/ns/cgroup"); !os.IsNotExist(err) {
return true
}
return false
}
// timeNsSupported checks whether time namespaces are supported.
func timeNsSupported() bool {
if _, err := os.Stat("/proc/self/ns/time"); !os.IsNotExist(err) {
return true
}
return false
}
func cgroupEnabled(mountPoint, name string) bool {
_, err := os.Stat(path.Join(mountPoint, name))
return err == nil
}
func readProcBool(path string) bool {
val, err := os.ReadFile(path)
if err != nil {
return false
}
return strings.TrimSpace(string(val)) == "1"
}
// defaultMaxCPUs is the normal maximum number of CPUs on Linux.
const defaultMaxCPUs = 8192
func isCpusetListAvailable(requested string, available map[int]struct{}) (bool, error) {
// Start with the normal maximum number of CPUs on Linux, but accept
// more if we actually have more CPUs available.
//
// This limit was added in f8e876d7616469d07b8b049ecb48967eeb8fa7a5
// to address CVE-2018-20699:
//
// Using a value such as `--cpuset-mems=1-9223372036854775807` would cause
// dockerd to run out of memory allocating a map of the values in the
// validation code. Set limits to the normal limit of the number of CPUs.
//
// More details in https://github.com/docker-archive/engine/pull/70#issuecomment-458458288
maxCPUs := defaultMaxCPUs
for m := range available {
if m > maxCPUs {
maxCPUs = m
}
}
parsedRequested, err := parseUintList(requested, maxCPUs)
if err != nil {
return false, err
}
for k := range parsedRequested {
if _, ok := available[k]; !ok {
return false, nil
}
}
return true, nil
}
// parseUintList parses and validates the specified string as the value
// found in some cgroup file (e.g. `cpuset.cpus`, `cpuset.mems`), which could be
// one of the formats below. Note that duplicates are actually allowed in the
// input string. It returns a `map[int]bool` with available elements from `val`
// set to `true`. Values larger than `maximum` cause an error if max is non-zero,
// in order to stop the map becoming excessively large.
// Supported formats:
//
// 7
// 1-6
// 0,3-4,7,8-10
// 0-0,0,1-7
// 03,1-3 <- this is gonna get parsed as [1,2,3]
// 3,2,1
// 0-2,3,1
func parseUintList(val string, maximum int) (map[int]struct{}, error) {
if val == "" {
return map[int]struct{}{}, nil
}
availableInts := make(map[int]struct{})
errInvalidFormat := fmt.Errorf("invalid format: %s", val)
for r := range strings.SplitSeq(val, ",") {
if !strings.Contains(r, "-") {
v, err := strconv.Atoi(r)
if err != nil {
return nil, errInvalidFormat
}
if maximum != 0 && v > maximum {
return nil, fmt.Errorf("value of out range, maximum is %d", maximum)
}
availableInts[v] = struct{}{}
} else {
minS, maxS, _ := strings.Cut(r, "-")
minAvailable, err := strconv.Atoi(minS)
if err != nil {
return nil, errInvalidFormat
}
maxAvailable, err := strconv.Atoi(maxS)
if err != nil {
return nil, errInvalidFormat
}
if maxAvailable < minAvailable {
return nil, errInvalidFormat
}
if maximum != 0 && maxAvailable > maximum {
return nil, fmt.Errorf("value of out range, maximum is %d", maximum)
}
for i := minAvailable; i <= maxAvailable; i++ {
availableInts[i] = struct{}{}
}
}
}
return availableInts, nil
}