netbird/client/firewall/iptables/acl_linux.go

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package iptables
import (
"fmt"
"net"
"strconv"
"github.com/coreos/go-iptables/iptables"
"github.com/google/uuid"
"github.com/nadoo/ipset"
log "github.com/sirupsen/logrus"
firewall "github.com/netbirdio/netbird/client/firewall/manager"
"github.com/netbirdio/netbird/client/internal/statemanager"
nbnet "github.com/netbirdio/netbird/util/net"
)
const (
tableName = "filter"
// rules chains contains the effective ACL rules
chainNameInputRules = "NETBIRD-ACL-INPUT"
chainNameOutputRules = "NETBIRD-ACL-OUTPUT"
)
type aclEntries map[string][][]string
type entry struct {
spec []string
position int
}
type aclManager struct {
iptablesClient *iptables.IPTables
wgIface iFaceMapper
routingFwChainName string
entries aclEntries
optionalEntries map[string][]entry
ipsetStore *ipsetStore
stateManager *statemanager.Manager
}
func newAclManager(iptablesClient *iptables.IPTables, wgIface iFaceMapper, routingFwChainName string) (*aclManager, error) {
m := &aclManager{
iptablesClient: iptablesClient,
wgIface: wgIface,
routingFwChainName: routingFwChainName,
entries: make(map[string][][]string),
optionalEntries: make(map[string][]entry),
ipsetStore: newIpsetStore(),
}
if err := ipset.Init(); err != nil {
return nil, fmt.Errorf("init ipset: %w", err)
}
return m, nil
}
func (m *aclManager) init(stateManager *statemanager.Manager) error {
m.stateManager = stateManager
m.seedInitialEntries()
m.seedInitialOptionalEntries()
if err := m.cleanChains(); err != nil {
return fmt.Errorf("clean chains: %w", err)
}
if err := m.createDefaultChains(); err != nil {
return fmt.Errorf("create default chains: %w", err)
}
m.updateState()
return nil
}
func (m *aclManager) AddPeerFiltering(
ip net.IP,
protocol firewall.Protocol,
sPort *firewall.Port,
dPort *firewall.Port,
direction firewall.RuleDirection,
action firewall.Action,
ipsetName string,
) ([]firewall.Rule, error) {
var dPortVal, sPortVal string
if dPort != nil && dPort.Values != nil {
// TODO: we support only one port per rule in current implementation of ACLs
dPortVal = strconv.Itoa(dPort.Values[0])
}
if sPort != nil && sPort.Values != nil {
sPortVal = strconv.Itoa(sPort.Values[0])
}
var chain string
if direction == firewall.RuleDirectionOUT {
chain = chainNameOutputRules
} else {
chain = chainNameInputRules
}
ipsetName = transformIPsetName(ipsetName, sPortVal, dPortVal)
specs := filterRuleSpecs(ip, string(protocol), sPortVal, dPortVal, direction, action, ipsetName)
if ipsetName != "" {
if ipList, ipsetExists := m.ipsetStore.ipset(ipsetName); ipsetExists {
if err := ipset.Add(ipsetName, ip.String()); err != nil {
return nil, fmt.Errorf("failed to add IP to ipset: %w", err)
}
// if ruleset already exists it means we already have the firewall rule
// so we need to update IPs in the ruleset and return new fw.Rule object for ACL manager.
ipList.addIP(ip.String())
return []firewall.Rule{&Rule{
ruleID: uuid.New().String(),
ipsetName: ipsetName,
ip: ip.String(),
chain: chain,
specs: specs,
}}, nil
}
if err := ipset.Flush(ipsetName); err != nil {
log.Errorf("flush ipset %s before use it: %s", ipsetName, err)
}
if err := ipset.Create(ipsetName); err != nil {
return nil, fmt.Errorf("failed to create ipset: %w", err)
}
if err := ipset.Add(ipsetName, ip.String()); err != nil {
return nil, fmt.Errorf("failed to add IP to ipset: %w", err)
}
ipList := newIpList(ip.String())
m.ipsetStore.addIpList(ipsetName, ipList)
}
ok, err := m.iptablesClient.Exists("filter", chain, specs...)
if err != nil {
return nil, fmt.Errorf("failed to check rule: %w", err)
}
if ok {
return nil, fmt.Errorf("rule already exists")
}
if err := m.iptablesClient.Append("filter", chain, specs...); err != nil {
return nil, err
}
rule := &Rule{
ruleID: uuid.New().String(),
specs: specs,
ipsetName: ipsetName,
ip: ip.String(),
chain: chain,
}
m.updateState()
return []firewall.Rule{rule}, nil
}
// DeletePeerRule from the firewall by rule definition
func (m *aclManager) DeletePeerRule(rule firewall.Rule) error {
r, ok := rule.(*Rule)
if !ok {
return fmt.Errorf("invalid rule type")
}
if ipsetList, ok := m.ipsetStore.ipset(r.ipsetName); ok {
// delete IP from ruleset IPs list and ipset
if _, ok := ipsetList.ips[r.ip]; ok {
if err := ipset.Del(r.ipsetName, r.ip); err != nil {
return fmt.Errorf("failed to delete ip from ipset: %w", err)
}
delete(ipsetList.ips, r.ip)
}
// if after delete, set still contains other IPs,
// no need to delete firewall rule and we should exit here
if len(ipsetList.ips) != 0 {
return nil
}
// we delete last IP from the set, that means we need to delete
// set itself and associated firewall rule too
m.ipsetStore.deleteIpset(r.ipsetName)
if err := ipset.Destroy(r.ipsetName); err != nil {
log.Errorf("delete empty ipset: %v", err)
}
}
if err := m.iptablesClient.Delete(tableName, r.chain, r.specs...); err != nil {
return fmt.Errorf("failed to delete rule: %s, %v: %w", r.chain, r.specs, err)
}
m.updateState()
return nil
}
func (m *aclManager) Reset() error {
if err := m.cleanChains(); err != nil {
return fmt.Errorf("clean chains: %w", err)
}
m.updateState()
return nil
}
// todo write less destructive cleanup mechanism
func (m *aclManager) cleanChains() error {
ok, err := m.iptablesClient.ChainExists(tableName, chainNameOutputRules)
if err != nil {
log.Debugf("failed to list chains: %s", err)
return err
}
if ok {
rules := m.entries["OUTPUT"]
for _, rule := range rules {
err := m.iptablesClient.DeleteIfExists(tableName, "OUTPUT", rule...)
if err != nil {
log.Errorf("failed to delete rule: %v, %s", rule, err)
}
}
err = m.iptablesClient.ClearAndDeleteChain(tableName, chainNameOutputRules)
if err != nil {
log.Debugf("failed to clear and delete %s chain: %s", chainNameOutputRules, err)
return err
}
}
ok, err = m.iptablesClient.ChainExists(tableName, chainNameInputRules)
if err != nil {
log.Debugf("failed to list chains: %s", err)
return err
}
if ok {
for _, rule := range m.entries["INPUT"] {
err := m.iptablesClient.DeleteIfExists(tableName, "INPUT", rule...)
if err != nil {
log.Errorf("failed to delete rule: %v, %s", rule, err)
}
}
for _, rule := range m.entries["FORWARD"] {
err := m.iptablesClient.DeleteIfExists(tableName, "FORWARD", rule...)
if err != nil {
log.Errorf("failed to delete rule: %v, %s", rule, err)
}
}
err = m.iptablesClient.ClearAndDeleteChain(tableName, chainNameInputRules)
if err != nil {
log.Debugf("failed to clear and delete %s chain: %s", chainNameInputRules, err)
return err
}
}
ok, err = m.iptablesClient.ChainExists("mangle", "PREROUTING")
if err != nil {
return fmt.Errorf("list chains: %w", err)
}
if ok {
for _, rule := range m.entries["PREROUTING"] {
err := m.iptablesClient.DeleteIfExists("mangle", "PREROUTING", rule...)
if err != nil {
log.Errorf("failed to delete rule: %v, %s", rule, err)
}
}
}
for _, ipsetName := range m.ipsetStore.ipsetNames() {
if err := ipset.Flush(ipsetName); err != nil {
log.Errorf("flush ipset %q during reset: %v", ipsetName, err)
}
if err := ipset.Destroy(ipsetName); err != nil {
log.Errorf("delete ipset %q during reset: %v", ipsetName, err)
}
m.ipsetStore.deleteIpset(ipsetName)
}
return nil
}
func (m *aclManager) createDefaultChains() error {
// chain netbird-acl-input-rules
if err := m.iptablesClient.NewChain(tableName, chainNameInputRules); err != nil {
log.Debugf("failed to create '%s' chain: %s", chainNameInputRules, err)
return err
}
// chain netbird-acl-output-rules
if err := m.iptablesClient.NewChain(tableName, chainNameOutputRules); err != nil {
log.Debugf("failed to create '%s' chain: %s", chainNameOutputRules, err)
return err
}
for chainName, rules := range m.entries {
for _, rule := range rules {
if err := m.iptablesClient.InsertUnique(tableName, chainName, 1, rule...); err != nil {
log.Debugf("failed to create input chain jump rule: %s", err)
return err
}
}
}
for chainName, entries := range m.optionalEntries {
for _, entry := range entries {
if err := m.iptablesClient.InsertUnique(tableName, chainName, entry.position, entry.spec...); err != nil {
log.Errorf("failed to insert optional entry %v: %v", entry.spec, err)
continue
}
m.entries[chainName] = append(m.entries[chainName], entry.spec)
}
}
clear(m.optionalEntries)
return nil
}
// seedInitialEntries adds default rules to the entries map, rules are inserted on pos 1, hence the order is reversed.
// We want to make sure our traffic is not dropped by existing rules.
// The existing FORWARD rules/policies decide outbound traffic towards our interface.
// In case the FORWARD policy is set to "drop", we add an established/related rule to allow return traffic for the inbound rule.
// The OUTPUT chain gets an extra rule to allow traffic to any set up routes, the return traffic is handled by the INPUT related/established rule.
func (m *aclManager) seedInitialEntries() {
established := getConntrackEstablished()
m.appendToEntries("INPUT", []string{"-i", m.wgIface.Name(), "-j", "DROP"})
m.appendToEntries("INPUT", []string{"-i", m.wgIface.Name(), "-j", chainNameInputRules})
m.appendToEntries("INPUT", append([]string{"-i", m.wgIface.Name()}, established...))
m.appendToEntries("OUTPUT", []string{"-o", m.wgIface.Name(), "-j", "DROP"})
m.appendToEntries("OUTPUT", []string{"-o", m.wgIface.Name(), "-j", chainNameOutputRules})
m.appendToEntries("OUTPUT", []string{"-o", m.wgIface.Name(), "!", "-d", m.wgIface.Address().String(), "-j", "ACCEPT"})
m.appendToEntries("OUTPUT", append([]string{"-o", m.wgIface.Name()}, established...))
m.appendToEntries("FORWARD", []string{"-i", m.wgIface.Name(), "-j", "DROP"})
m.appendToEntries("FORWARD", []string{"-i", m.wgIface.Name(), "-j", m.routingFwChainName})
m.appendToEntries("FORWARD", append([]string{"-o", m.wgIface.Name()}, established...))
}
func (m *aclManager) seedInitialOptionalEntries() {
m.optionalEntries["FORWARD"] = []entry{
{
spec: []string{"-m", "mark", "--mark", fmt.Sprintf("%#x", nbnet.PreroutingFwmarkRedirected), "-j", chainNameInputRules},
position: 2,
},
}
m.optionalEntries["PREROUTING"] = []entry{
{
spec: []string{"-t", "mangle", "-i", m.wgIface.Name(), "-m", "addrtype", "--dst-type", "LOCAL", "-j", "MARK", "--set-mark", fmt.Sprintf("%#x", nbnet.PreroutingFwmarkRedirected)},
position: 1,
},
}
}
func (m *aclManager) appendToEntries(chainName string, spec []string) {
m.entries[chainName] = append(m.entries[chainName], spec)
}
func (m *aclManager) updateState() {
if m.stateManager == nil {
return
}
var currentState *ShutdownState
if existing := m.stateManager.GetState(currentState); existing != nil {
if existingState, ok := existing.(*ShutdownState); ok {
currentState = existingState
}
}
if currentState == nil {
currentState = &ShutdownState{}
}
currentState.Lock()
defer currentState.Unlock()
currentState.ACLEntries = m.entries
currentState.ACLIPsetStore = m.ipsetStore
if err := m.stateManager.UpdateState(currentState); err != nil {
log.Errorf("failed to update state: %v", err)
}
}
// filterRuleSpecs returns the specs of a filtering rule
func filterRuleSpecs(
ip net.IP, protocol string, sPort, dPort string, direction firewall.RuleDirection, action firewall.Action, ipsetName string,
) (specs []string) {
matchByIP := true
// don't use IP matching if IP is ip 0.0.0.0
if ip.String() == "0.0.0.0" {
matchByIP = false
}
switch direction {
case firewall.RuleDirectionIN:
if matchByIP {
if ipsetName != "" {
specs = append(specs, "-m", "set", "--set", ipsetName, "src")
} else {
specs = append(specs, "-s", ip.String())
}
}
case firewall.RuleDirectionOUT:
if matchByIP {
if ipsetName != "" {
specs = append(specs, "-m", "set", "--set", ipsetName, "dst")
} else {
specs = append(specs, "-d", ip.String())
}
}
}
if protocol != "all" {
specs = append(specs, "-p", protocol)
}
if sPort != "" {
specs = append(specs, "--sport", sPort)
}
if dPort != "" {
specs = append(specs, "--dport", dPort)
}
return append(specs, "-j", actionToStr(action))
}
func actionToStr(action firewall.Action) string {
if action == firewall.ActionAccept {
return "ACCEPT"
}
return "DROP"
}
func transformIPsetName(ipsetName string, sPort, dPort string) string {
switch {
case ipsetName == "":
return ""
case sPort != "" && dPort != "":
return ipsetName + "-sport-dport"
case sPort != "":
return ipsetName + "-sport"
case dPort != "":
return ipsetName + "-dport"
default:
return ipsetName
}
}