mirror of
https://github.com/apernet/OpenGFW.git
synced 2024-12-23 01:19:21 +08:00
409 lines
9.5 KiB
Go
409 lines
9.5 KiB
Go
package io
|
|
|
|
import (
|
|
"context"
|
|
"encoding/binary"
|
|
"errors"
|
|
"fmt"
|
|
"os/exec"
|
|
"strconv"
|
|
"strings"
|
|
|
|
"github.com/coreos/go-iptables/iptables"
|
|
"github.com/florianl/go-nfqueue"
|
|
"github.com/mdlayher/netlink"
|
|
"golang.org/x/sys/unix"
|
|
)
|
|
|
|
const (
|
|
nfqueueNum = 100
|
|
nfqueueMaxPacketLen = 0xFFFF
|
|
nfqueueDefaultQueueSize = 128
|
|
|
|
nfqueueConnMarkAccept = 1001
|
|
nfqueueConnMarkDrop = 1002
|
|
|
|
nftFamily = "inet"
|
|
nftTable = "opengfw"
|
|
)
|
|
|
|
func generateNftRules(local, rst bool) (*nftTableSpec, error) {
|
|
if local && rst {
|
|
return nil, errors.New("tcp rst is not supported in local mode")
|
|
}
|
|
table := &nftTableSpec{
|
|
Family: nftFamily,
|
|
Table: nftTable,
|
|
}
|
|
table.Defines = append(table.Defines, fmt.Sprintf("define ACCEPT_CTMARK=%d", nfqueueConnMarkAccept))
|
|
table.Defines = append(table.Defines, fmt.Sprintf("define DROP_CTMARK=%d", nfqueueConnMarkDrop))
|
|
table.Defines = append(table.Defines, fmt.Sprintf("define QUEUE_NUM=%d", nfqueueNum))
|
|
if local {
|
|
table.Chains = []nftChainSpec{
|
|
{Chain: "INPUT", Header: "type filter hook input priority filter; policy accept;"},
|
|
{Chain: "OUTPUT", Header: "type filter hook output priority filter; policy accept;"},
|
|
}
|
|
} else {
|
|
table.Chains = []nftChainSpec{
|
|
{Chain: "FORWARD", Header: "type filter hook forward priority filter; policy accept;"},
|
|
}
|
|
}
|
|
for i := range table.Chains {
|
|
c := &table.Chains[i]
|
|
c.Rules = append(c.Rules, "ct mark $ACCEPT_CTMARK counter accept")
|
|
if rst {
|
|
c.Rules = append(c.Rules, "ip protocol tcp ct mark $DROP_CTMARK counter reject with tcp reset")
|
|
}
|
|
c.Rules = append(c.Rules, "ct mark $DROP_CTMARK counter drop")
|
|
c.Rules = append(c.Rules, "counter queue num $QUEUE_NUM bypass")
|
|
}
|
|
return table, nil
|
|
}
|
|
|
|
func generateIptRules(local, rst bool) ([]iptRule, error) {
|
|
if local && rst {
|
|
return nil, errors.New("tcp rst is not supported in local mode")
|
|
}
|
|
var chains []string
|
|
if local {
|
|
chains = []string{"INPUT", "OUTPUT"}
|
|
} else {
|
|
chains = []string{"FORWARD"}
|
|
}
|
|
rules := make([]iptRule, 0, 4*len(chains))
|
|
for _, chain := range chains {
|
|
rules = append(rules, iptRule{"filter", chain, []string{"-m", "connmark", "--mark", strconv.Itoa(nfqueueConnMarkAccept), "-j", "ACCEPT"}})
|
|
if rst {
|
|
rules = append(rules, iptRule{"filter", chain, []string{"-p", "tcp", "-m", "connmark", "--mark", strconv.Itoa(nfqueueConnMarkDrop), "-j", "REJECT", "--reject-with", "tcp-reset"}})
|
|
}
|
|
rules = append(rules, iptRule{"filter", chain, []string{"-m", "connmark", "--mark", strconv.Itoa(nfqueueConnMarkDrop), "-j", "DROP"}})
|
|
rules = append(rules, iptRule{"filter", chain, []string{"-j", "NFQUEUE", "--queue-num", strconv.Itoa(nfqueueNum), "--queue-bypass"}})
|
|
}
|
|
|
|
return rules, nil
|
|
}
|
|
|
|
var _ PacketIO = (*nfqueuePacketIO)(nil)
|
|
|
|
var errNotNFQueuePacket = errors.New("not an NFQueue packet")
|
|
|
|
type nfqueuePacketIO struct {
|
|
n *nfqueue.Nfqueue
|
|
local bool
|
|
rst bool
|
|
rSet bool // whether the nftables/iptables rules have been set
|
|
|
|
// iptables not nil = use iptables instead of nftables
|
|
ipt4 *iptables.IPTables
|
|
ipt6 *iptables.IPTables
|
|
}
|
|
|
|
type NFQueuePacketIOConfig struct {
|
|
QueueSize uint32
|
|
ReadBuffer int
|
|
WriteBuffer int
|
|
Local bool
|
|
RST bool
|
|
}
|
|
|
|
func NewNFQueuePacketIO(config NFQueuePacketIOConfig) (PacketIO, error) {
|
|
if config.QueueSize == 0 {
|
|
config.QueueSize = nfqueueDefaultQueueSize
|
|
}
|
|
var ipt4, ipt6 *iptables.IPTables
|
|
var err error
|
|
if nftCheck() != nil {
|
|
// We prefer nftables, but if it's not available, fall back to iptables
|
|
ipt4, err = iptables.NewWithProtocol(iptables.ProtocolIPv4)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
ipt6, err = iptables.NewWithProtocol(iptables.ProtocolIPv6)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
n, err := nfqueue.Open(&nfqueue.Config{
|
|
NfQueue: nfqueueNum,
|
|
MaxPacketLen: nfqueueMaxPacketLen,
|
|
MaxQueueLen: config.QueueSize,
|
|
Copymode: nfqueue.NfQnlCopyPacket,
|
|
Flags: nfqueue.NfQaCfgFlagConntrack,
|
|
})
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if config.ReadBuffer > 0 {
|
|
err = n.Con.SetReadBuffer(config.ReadBuffer)
|
|
if err != nil {
|
|
_ = n.Close()
|
|
return nil, err
|
|
}
|
|
}
|
|
if config.WriteBuffer > 0 {
|
|
err = n.Con.SetWriteBuffer(config.WriteBuffer)
|
|
if err != nil {
|
|
_ = n.Close()
|
|
return nil, err
|
|
}
|
|
}
|
|
return &nfqueuePacketIO{
|
|
n: n,
|
|
local: config.Local,
|
|
rst: config.RST,
|
|
ipt4: ipt4,
|
|
ipt6: ipt6,
|
|
}, nil
|
|
}
|
|
|
|
func (n *nfqueuePacketIO) Register(ctx context.Context, cb PacketCallback) error {
|
|
err := n.n.RegisterWithErrorFunc(ctx,
|
|
func(a nfqueue.Attribute) int {
|
|
if ok, verdict := n.packetAttributeSanityCheck(a); !ok {
|
|
if a.PacketID != nil {
|
|
_ = n.n.SetVerdict(*a.PacketID, verdict)
|
|
}
|
|
return 0
|
|
}
|
|
p := &nfqueuePacket{
|
|
id: *a.PacketID,
|
|
streamID: ctIDFromCtBytes(*a.Ct),
|
|
data: *a.Payload,
|
|
}
|
|
return okBoolToInt(cb(p, nil))
|
|
},
|
|
func(e error) int {
|
|
if opErr := (*netlink.OpError)(nil); errors.As(e, &opErr) {
|
|
if errors.Is(opErr.Err, unix.ENOBUFS) {
|
|
// Kernel buffer temporarily full, ignore
|
|
return 0
|
|
}
|
|
}
|
|
return okBoolToInt(cb(nil, e))
|
|
})
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if !n.rSet {
|
|
if n.ipt4 != nil {
|
|
err = n.setupIpt(n.local, n.rst, false)
|
|
} else {
|
|
err = n.setupNft(n.local, n.rst, false)
|
|
}
|
|
if err != nil {
|
|
return err
|
|
}
|
|
n.rSet = true
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (n *nfqueuePacketIO) packetAttributeSanityCheck(a nfqueue.Attribute) (ok bool, verdict int) {
|
|
if a.PacketID == nil {
|
|
// Re-inject to NFQUEUE is actually not possible in this condition
|
|
return false, -1
|
|
}
|
|
if a.Payload == nil || len(*a.Payload) < 20 {
|
|
// 20 is the minimum possible size of an IP packet
|
|
return false, nfqueue.NfDrop
|
|
}
|
|
if a.Ct == nil {
|
|
// Multicast packets may not have a conntrack, but only appear in local mode
|
|
if n.local {
|
|
return false, nfqueue.NfAccept
|
|
}
|
|
return false, nfqueue.NfDrop
|
|
}
|
|
return true, -1
|
|
}
|
|
|
|
func (n *nfqueuePacketIO) SetVerdict(p Packet, v Verdict, newPacket []byte) error {
|
|
nP, ok := p.(*nfqueuePacket)
|
|
if !ok {
|
|
return &ErrInvalidPacket{Err: errNotNFQueuePacket}
|
|
}
|
|
switch v {
|
|
case VerdictAccept:
|
|
return n.n.SetVerdict(nP.id, nfqueue.NfAccept)
|
|
case VerdictAcceptModify:
|
|
return n.n.SetVerdictModPacket(nP.id, nfqueue.NfAccept, newPacket)
|
|
case VerdictAcceptStream:
|
|
return n.n.SetVerdictWithConnMark(nP.id, nfqueue.NfAccept, nfqueueConnMarkAccept)
|
|
case VerdictDrop:
|
|
return n.n.SetVerdict(nP.id, nfqueue.NfDrop)
|
|
case VerdictDropStream:
|
|
return n.n.SetVerdictWithConnMark(nP.id, nfqueue.NfDrop, nfqueueConnMarkDrop)
|
|
default:
|
|
// Invalid verdict, ignore for now
|
|
return nil
|
|
}
|
|
}
|
|
|
|
func (n *nfqueuePacketIO) Close() error {
|
|
if n.rSet {
|
|
if n.ipt4 != nil {
|
|
_ = n.setupIpt(n.local, n.rst, true)
|
|
} else {
|
|
_ = n.setupNft(n.local, n.rst, true)
|
|
}
|
|
n.rSet = false
|
|
}
|
|
return n.n.Close()
|
|
}
|
|
|
|
func (n *nfqueuePacketIO) setupNft(local, rst, remove bool) error {
|
|
rules, err := generateNftRules(local, rst)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
rulesText := rules.String()
|
|
if remove {
|
|
err = nftDelete(nftFamily, nftTable)
|
|
} else {
|
|
// Delete first to make sure no leftover rules
|
|
_ = nftDelete(nftFamily, nftTable)
|
|
err = nftAdd(rulesText)
|
|
}
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (n *nfqueuePacketIO) setupIpt(local, rst, remove bool) error {
|
|
rules, err := generateIptRules(local, rst)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if remove {
|
|
err = iptsBatchDeleteIfExists([]*iptables.IPTables{n.ipt4, n.ipt6}, rules)
|
|
} else {
|
|
err = iptsBatchAppendUnique([]*iptables.IPTables{n.ipt4, n.ipt6}, rules)
|
|
}
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
var _ Packet = (*nfqueuePacket)(nil)
|
|
|
|
type nfqueuePacket struct {
|
|
id uint32
|
|
streamID uint32
|
|
data []byte
|
|
}
|
|
|
|
func (p *nfqueuePacket) StreamID() uint32 {
|
|
return p.streamID
|
|
}
|
|
|
|
func (p *nfqueuePacket) Data() []byte {
|
|
return p.data
|
|
}
|
|
|
|
func okBoolToInt(ok bool) int {
|
|
if ok {
|
|
return 0
|
|
} else {
|
|
return 1
|
|
}
|
|
}
|
|
|
|
func nftCheck() error {
|
|
_, err := exec.LookPath("nft")
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func nftAdd(input string) error {
|
|
cmd := exec.Command("nft", "-f", "-")
|
|
cmd.Stdin = strings.NewReader(input)
|
|
return cmd.Run()
|
|
}
|
|
|
|
func nftDelete(family, table string) error {
|
|
cmd := exec.Command("nft", "delete", "table", family, table)
|
|
return cmd.Run()
|
|
}
|
|
|
|
type nftTableSpec struct {
|
|
Defines []string
|
|
Family, Table string
|
|
Chains []nftChainSpec
|
|
}
|
|
|
|
func (t *nftTableSpec) String() string {
|
|
chains := make([]string, 0, len(t.Chains))
|
|
for _, c := range t.Chains {
|
|
chains = append(chains, c.String())
|
|
}
|
|
|
|
return fmt.Sprintf(`
|
|
%s
|
|
|
|
table %s %s {
|
|
%s
|
|
}
|
|
`, strings.Join(t.Defines, "\n"), t.Family, t.Table, strings.Join(chains, ""))
|
|
}
|
|
|
|
type nftChainSpec struct {
|
|
Chain string
|
|
Header string
|
|
Rules []string
|
|
}
|
|
|
|
func (c *nftChainSpec) String() string {
|
|
return fmt.Sprintf(`
|
|
chain %s {
|
|
%s
|
|
%s
|
|
}
|
|
`, c.Chain, c.Header, strings.Join(c.Rules, "\n\x20\x20\x20\x20"))
|
|
}
|
|
|
|
type iptRule struct {
|
|
Table, Chain string
|
|
RuleSpec []string
|
|
}
|
|
|
|
func iptsBatchAppendUnique(ipts []*iptables.IPTables, rules []iptRule) error {
|
|
for _, r := range rules {
|
|
for _, ipt := range ipts {
|
|
err := ipt.AppendUnique(r.Table, r.Chain, r.RuleSpec...)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func iptsBatchDeleteIfExists(ipts []*iptables.IPTables, rules []iptRule) error {
|
|
for _, r := range rules {
|
|
for _, ipt := range ipts {
|
|
err := ipt.DeleteIfExists(r.Table, r.Chain, r.RuleSpec...)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func ctIDFromCtBytes(ct []byte) uint32 {
|
|
ctAttrs, err := netlink.UnmarshalAttributes(ct)
|
|
if err != nil {
|
|
return 0
|
|
}
|
|
for _, attr := range ctAttrs {
|
|
if attr.Type == 12 { // CTA_ID
|
|
return binary.BigEndian.Uint32(attr.Data)
|
|
}
|
|
}
|
|
return 0
|
|
}
|