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probes.go
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probes.go
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// SPDX-License-Identifier: Apache-2.0
// Copyright 2019-2021 Authors of Cilium
package probes
import (
"bufio"
"bytes"
"encoding/json"
"errors"
"fmt"
"io"
"os"
"path/filepath"
"strconv"
"strings"
"sync"
"github.com/cilium/cilium/pkg/command/exec"
"github.com/cilium/cilium/pkg/defaults"
"github.com/cilium/cilium/pkg/logging"
"github.com/cilium/cilium/pkg/logging/logfields"
"github.com/cilium/cilium/pkg/option"
"golang.org/x/sys/unix"
)
var (
log = logging.DefaultLogger.WithField(logfields.LogSubsys, "probes")
once sync.Once
probeManager *ProbeManager
)
// ErrKernelConfigNotFound is the error returned if the kernel config is unavailable
// to the cilium agent.
var ErrKernelConfigNotFound = errors.New("Kernel Config file not found")
// KernelParam is a type based on string which represents CONFIG_* kernel
// parameters which usually have values "y", "n" or "m".
type KernelParam string
// Enabled checks whether the kernel parameter is enabled.
func (kp KernelParam) Enabled() bool {
return kp == "y"
}
// Module checks whether the kernel parameter is enabled as a module.
func (kp KernelParam) Module() bool {
return kp == "m"
}
// kernelOption holds information about kernel parameters to probe.
type kernelOption struct {
Description string
Enabled bool
CanBeModule bool
}
// SystemConfig contains kernel configuration and sysctl parameters related to
// BPF functionality.
type SystemConfig struct {
UnprivilegedBpfDisabled int `json:"unprivileged_bpf_disabled"`
BpfJitEnable int `json:"bpf_jit_enable"`
BpfJitHarden int `json:"bpf_jit_harden"`
BpfJitKallsyms int `json:"bpf_jit_kallsyms"`
BpfJitLimit int `json:"bpf_jit_limit"`
ConfigBpf KernelParam `json:"CONFIG_BPF"`
ConfigBpfSyscall KernelParam `json:"CONFIG_BPF_SYSCALL"`
ConfigHaveEbpfJit KernelParam `json:"CONFIG_HAVE_EBPF_JIT"`
ConfigBpfJit KernelParam `json:"CONFIG_BPF_JIT"`
ConfigBpfJitAlwaysOn KernelParam `json:"CONFIG_BPF_JIT_ALWAYS_ON"`
ConfigCgroups KernelParam `json:"CONFIG_CGROUPS"`
ConfigCgroupBpf KernelParam `json:"CONFIG_CGROUP_BPF"`
ConfigCgroupNetClassID KernelParam `json:"CONFIG_CGROUP_NET_CLASSID"`
ConfigSockCgroupData KernelParam `json:"CONFIG_SOCK_CGROUP_DATA"`
ConfigBpfEvents KernelParam `json:"CONFIG_BPF_EVENTS"`
ConfigKprobeEvents KernelParam `json:"CONFIG_KPROBE_EVENTS"`
ConfigUprobeEvents KernelParam `json:"CONFIG_UPROBE_EVENTS"`
ConfigTracing KernelParam `json:"CONFIG_TRACING"`
ConfigFtraceSyscalls KernelParam `json:"CONFIG_FTRACE_SYSCALLS"`
ConfigFunctionErrorInjection KernelParam `json:"CONFIG_FUNCTION_ERROR_INJECTION"`
ConfigBpfKprobeOverride KernelParam `json:"CONFIG_BPF_KPROBE_OVERRIDE"`
ConfigNet KernelParam `json:"CONFIG_NET"`
ConfigXdpSockets KernelParam `json:"CONFIG_XDP_SOCKETS"`
ConfigLwtunnelBpf KernelParam `json:"CONFIG_LWTUNNEL_BPF"`
ConfigNetActBpf KernelParam `json:"CONFIG_NET_ACT_BPF"`
ConfigNetClsBpf KernelParam `json:"CONFIG_NET_CLS_BPF"`
ConfigNetClsAct KernelParam `json:"CONFIG_NET_CLS_ACT"`
ConfigNetSchIngress KernelParam `json:"CONFIG_NET_SCH_INGRESS"`
ConfigXfrm KernelParam `json:"CONFIG_XFRM"`
ConfigIPRouteClassID KernelParam `json:"CONFIG_IP_ROUTE_CLASSID"`
ConfigIPv6Seg6Bpf KernelParam `json:"CONFIG_IPV6_SEG6_BPF"`
ConfigBpfLircMode2 KernelParam `json:"CONFIG_BPF_LIRC_MODE2"`
ConfigBpfStreamParser KernelParam `json:"CONFIG_BPF_STREAM_PARSER"`
ConfigNetfilterXtMatchBpf KernelParam `json:"CONFIG_NETFILTER_XT_MATCH_BPF"`
ConfigBpfilter KernelParam `json:"CONFIG_BPFILTER"`
ConfigBpfilterUmh KernelParam `json:"CONFIG_BPFILTER_UMH"`
ConfigTestBpf KernelParam `json:"CONFIG_TEST_BPF"`
ConfigKernelHz KernelParam `json:"CONFIG_HZ"`
}
// MapTypes contains bools indicating which types of BPF maps the currently
// running kernel supports.
type MapTypes struct {
HaveHashMapType bool `json:"have_hash_map_type"`
HaveArrayMapType bool `json:"have_array_map_type"`
HaveProgArrayMapType bool `json:"have_prog_array_map_type"`
HavePerfEventArrayMapType bool `json:"have_perf_event_array_map_type"`
HavePercpuHashMapType bool `json:"have_percpu_hash_map_type"`
HavePercpuArrayMapType bool `json:"have_percpu_array_map_type"`
HaveStackTraceMapType bool `json:"have_stack_trace_map_type"`
HaveCgroupArrayMapType bool `json:"have_cgroup_array_map_type"`
HaveLruHashMapType bool `json:"have_lru_hash_map_type"`
HaveLruPercpuHashMapType bool `json:"have_lru_percpu_hash_map_type"`
HaveLpmTrieMapType bool `json:"have_lpm_trie_map_type"`
HaveArrayOfMapsMapType bool `json:"have_array_of_maps_map_type"`
HaveHashOfMapsMapType bool `json:"have_hash_of_maps_map_type"`
HaveDevmapMapType bool `json:"have_devmap_map_type"`
HaveSockmapMapType bool `json:"have_sockmap_map_type"`
HaveCpumapMapType bool `json:"have_cpumap_map_type"`
HaveXskmapMapType bool `json:"have_xskmap_map_type"`
HaveSockhashMapType bool `json:"have_sockhash_map_type"`
HaveCgroupStorageMapType bool `json:"have_cgroup_storage_map_type"`
HaveReuseportSockarrayMapType bool `json:"have_reuseport_sockarray_map_type"`
HavePercpuCgroupStorageMapType bool `json:"have_percpu_cgroup_storage_map_type"`
HaveQueueMapType bool `json:"have_queue_map_type"`
HaveStackMapType bool `json:"have_stack_map_type"`
}
// Kernel misc configurations kernel large 1M instructions support
type Misc struct {
HaveLargeInsnLimit bool `json:"have_large_insn_limit"`
}
// Features contains BPF feature checks returned by bpftool.
type Features struct {
SystemConfig `json:"system_config"`
MapTypes `json:"map_types"`
Helpers map[string][]string `json:"helpers"`
Misc `json:"misc"`
}
// ProbeManager is a manager of BPF feature checks.
type ProbeManager struct {
features Features
}
// NewProbeManager returns a new instance of ProbeManager - a manager of BPF
// feature checks.
func NewProbeManager() *ProbeManager {
newProbeManager := func() {
probeManager = &ProbeManager{}
probeManager.features = probeManager.Probe()
}
once.Do(newProbeManager)
return probeManager
}
// Probe probes the underlying kernel for features.
func (*ProbeManager) Probe() Features {
var features Features
out, err := exec.WithTimeout(
defaults.ExecTimeout,
"bpftool", "-j", "feature", "probe",
).CombinedOutput(log, true)
if err != nil {
log.WithError(err).Fatal("could not run bpftool")
}
if err := json.Unmarshal(out, &features); err != nil {
log.WithError(err).Fatal("could not parse bpftool output")
}
return features
}
func (p *ProbeManager) probeSystemKernelHz() (int, error) {
out, err := exec.WithTimeout(
defaults.ExecTimeout,
"cilium-probe-kernel-hz",
).Output(log, false)
if err != nil {
return 0, fmt.Errorf("Cannot probe CONFIG_HZ")
}
hz := 0
warp := 0
n, _ := fmt.Sscanf(string(out), "%d, %d\n", &hz, &warp)
if n == 2 && hz > 0 && hz < 100000 {
return hz, nil
}
return 0, fmt.Errorf("Invalid probed CONFIG_HZ value")
}
// SystemKernelHz returns the HZ value that the kernel has been configured with.
func (p *ProbeManager) SystemKernelHz() (int, error) {
config := p.features.SystemConfig
if config.ConfigKernelHz == "" {
return p.probeSystemKernelHz()
}
hz, err := strconv.Atoi(string(config.ConfigKernelHz))
if err != nil {
return 0, err
}
if hz > 0 && hz < 100000 {
return hz, nil
}
return 0, fmt.Errorf("Invalid CONFIG_HZ value")
}
// SystemConfigProbes performs a check of kernel configuration parameters. It
// returns an error when parameters required by Cilium are not enabled. It logs
// warnings when optional parameters are not enabled.
func (p *ProbeManager) SystemConfigProbes() error {
if !p.KernelConfigAvailable() {
return ErrKernelConfigNotFound
}
requiredParams := p.GetRequiredConfig()
for param, kernelOption := range requiredParams {
if !kernelOption.Enabled {
module := ""
if kernelOption.CanBeModule {
module = " or module"
}
return fmt.Errorf("%s kernel parameter%s is required (needed for: %s)", param, module, kernelOption.Description)
}
}
optionalParams := p.GetOptionalConfig()
for param, kernelOption := range optionalParams {
if !kernelOption.Enabled {
module := ""
if kernelOption.CanBeModule {
module = " or module"
}
log.Warningf("%s optional kernel parameter%s is not in kernel (needed for: %s)", param, module, kernelOption.Description)
}
}
return nil
}
// GetRequiredConfig performs a check of mandatory kernel configuration options. It
// returns a map indicating which required kernel parameters are enabled - and which are not.
// GetRequiredConfig is being used by CLI "cilium kernel-check".
func (p *ProbeManager) GetRequiredConfig() map[KernelParam]kernelOption {
config := p.features.SystemConfig
coreInfraDescription := "Essential eBPF infrastructure"
kernelParams := make(map[KernelParam]kernelOption)
kernelParams["CONFIG_BPF"] = kernelOption{
Enabled: config.ConfigBpf.Enabled(),
Description: coreInfraDescription,
CanBeModule: false,
}
kernelParams["CONFIG_BPF_SYSCALL"] = kernelOption{
Enabled: config.ConfigBpfSyscall.Enabled(),
Description: coreInfraDescription,
CanBeModule: false,
}
kernelParams["CONFIG_NET_SCH_INGRESS"] = kernelOption{
Enabled: config.ConfigNetSchIngress.Enabled() || config.ConfigNetSchIngress.Module(),
Description: coreInfraDescription,
CanBeModule: true,
}
kernelParams["CONFIG_NET_CLS_BPF"] = kernelOption{
Enabled: config.ConfigNetClsBpf.Enabled() || config.ConfigNetClsBpf.Module(),
Description: coreInfraDescription,
CanBeModule: true,
}
kernelParams["CONFIG_NET_CLS_ACT"] = kernelOption{
Enabled: config.ConfigNetClsAct.Enabled(),
Description: coreInfraDescription,
CanBeModule: false,
}
kernelParams["CONFIG_BPF_JIT"] = kernelOption{
Enabled: config.ConfigBpfJit.Enabled(),
Description: coreInfraDescription,
CanBeModule: false,
}
kernelParams["CONFIG_HAVE_EBPF_JIT"] = kernelOption{
Enabled: config.ConfigHaveEbpfJit.Enabled(),
Description: coreInfraDescription,
CanBeModule: false,
}
return kernelParams
}
// GetOptionalConfig performs a check of *optional* kernel configuration options. It
// returns a map indicating which optional/non-mandatory kernel parameters are enabled.
// GetOptionalConfig is being used by CLI "cilium kernel-check".
func (p *ProbeManager) GetOptionalConfig() map[KernelParam]kernelOption {
config := p.features.SystemConfig
kernelParams := make(map[KernelParam]kernelOption)
kernelParams["CONFIG_CGROUP_BPF"] = kernelOption{
Enabled: config.ConfigCgroupBpf.Enabled(),
Description: "Host Reachable Services and Sockmap optimization",
CanBeModule: false,
}
kernelParams["CONFIG_LWTUNNEL_BPF"] = kernelOption{
Enabled: config.ConfigLwtunnelBpf.Enabled(),
Description: "Lightweight Tunnel hook for IP-in-IP encapsulation",
CanBeModule: false,
}
kernelParams["CONFIG_BPF_EVENTS"] = kernelOption{
Enabled: config.ConfigBpfEvents.Enabled(),
Description: "Visibility and congestion management with datapath",
CanBeModule: false,
}
return kernelParams
}
// GetMapTypes returns information about supported BPF map types.
func (p *ProbeManager) GetMapTypes() *MapTypes {
return &p.features.MapTypes
}
// GetMisc returns information about kernel misc.
func (p *ProbeManager) GetMisc() Misc {
return p.features.Misc
}
// GetHelpers returns information about available BPF helpers for the given
// program type.
// If program type is not found, returns nil.
func (p *ProbeManager) GetHelpers(prog string) map[string]struct{} {
for p, helpers := range p.features.Helpers {
if prog+"_available_helpers" == p {
ret := map[string]struct{}{}
for _, h := range helpers {
ret[h] = struct{}{}
}
return ret
}
}
return nil
}
// writeHeaders executes bpftool to generate BPF feature C macros and then
// writes them to the given writer.
func (p *ProbeManager) writeHeaders(featuresFile io.Writer) error {
cmd := exec.WithTimeout(
defaults.ExecTimeout, "bpftool", "feature", "probe", "macros")
stdoutPipe, err := cmd.StdoutPipe()
if err != nil {
return fmt.Errorf(
"could not initialize stdout pipe for bpftool feature probe: %w", err)
}
stderrPipe, err := cmd.StderrPipe()
if err != nil {
return fmt.Errorf(
"could not initialize stderr pipe for bpftool feature probe: %w", err)
}
if err := cmd.Start(); err != nil {
return fmt.Errorf(
"could not start bpftool for bpftool feature probe: %w", err)
}
writer := bufio.NewWriter(featuresFile)
defer writer.Flush()
io.WriteString(writer, "#ifndef BPF_FEATURES_H_\n")
io.WriteString(writer, "#define BPF_FEATURES_H_\n\n")
io.Copy(writer, stdoutPipe)
if err := cmd.Wait(); err != nil {
stderr, err := io.ReadAll(stderrPipe)
if err != nil {
return fmt.Errorf(
"reading from bpftool feature probe stderr pipe failed: %w", err)
}
return fmt.Errorf(
"bpftool feature probe did not run successfully: %s (%w)", stderr, err)
}
io.WriteString(writer, "#endif /* BPF_FEATURES_H_ */\n")
return nil
}
// CreateHeadersFile creates a C header file with macros indicating which BPF
// features are available in the kernel.
func (p *ProbeManager) CreateHeadersFile() error {
globalsDir := option.Config.GetGlobalsDir()
if err := os.MkdirAll(globalsDir, defaults.StateDirRights); err != nil {
return fmt.Errorf("could not create runtime directory %s: %w", globalsDir, err)
}
featuresFilePath := filepath.Join(globalsDir, "bpf_features.h")
featuresFile, err := os.Create(featuresFilePath)
if err != nil {
return fmt.Errorf(
"could not create features header file %s: %w", featuresFilePath, err)
}
defer featuresFile.Close()
if err := p.writeHeaders(featuresFile); err != nil {
return err
}
return nil
}
// KernelConfigAvailable checks if the Kernel Config is available on the
// system or not.
func (p *ProbeManager) KernelConfigAvailable() bool {
// Check Kernel Config is available or not.
// We are replicating BPFTools logic here to check if kernel config is available
// https://elixir.bootlin.com/linux/v5.7/source/tools/bpf/bpftool/feature.c#L390
info := unix.Utsname{}
err := unix.Uname(&info)
if err != nil {
return false
}
release := strings.TrimSpace(string(bytes.Trim(info.Release[:], "\x00")))
// Any error checking these files will return Kernel config not found error
if _, err := os.Stat(fmt.Sprintf("/boot/config-%s", release)); err != nil {
if _, err = os.Stat("/proc/config.gz"); err != nil {
return false
}
}
return true
}