499 lines
13 KiB
Go
499 lines
13 KiB
Go
// Copyright 2018 Google LLC. All Rights Reserved.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
// Package expr provides nftables rule expressions.
|
|
package expr
|
|
|
|
import (
|
|
"encoding/binary"
|
|
|
|
"github.com/google/nftables/binaryutil"
|
|
"github.com/google/nftables/internal/parseexprfunc"
|
|
"github.com/mdlayher/netlink"
|
|
"golang.org/x/sys/unix"
|
|
)
|
|
|
|
func init() {
|
|
parseExprBytesCommonFunc := func(exprsFromBytesFunc func() ([]Any, error)) ([]interface{}, error) {
|
|
exprs, err := exprsFromBytesFunc()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
result := make([]interface{}, len(exprs))
|
|
for idx, expr := range exprs {
|
|
result[idx] = expr
|
|
}
|
|
return result, nil
|
|
}
|
|
|
|
parseexprfunc.ParseExprBytesFromNameFunc = func(fam byte, ad *netlink.AttributeDecoder, exprName string) ([]interface{}, error) {
|
|
return parseExprBytesCommonFunc(func() ([]Any, error) {
|
|
return exprsBytesFromName(fam, ad, exprName)
|
|
})
|
|
}
|
|
parseexprfunc.ParseExprBytesFunc = func(fam byte, ad *netlink.AttributeDecoder) ([]interface{}, error) {
|
|
return parseExprBytesCommonFunc(func() ([]Any, error) {
|
|
return exprsFromBytes(fam, ad)
|
|
})
|
|
}
|
|
parseexprfunc.ParseExprMsgFunc = func(fam byte, b []byte) ([]interface{}, error) {
|
|
ad, err := netlink.NewAttributeDecoder(b)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
ad.ByteOrder = binary.BigEndian
|
|
var exprs []interface{}
|
|
for ad.Next() {
|
|
e, err := parseexprfunc.ParseExprBytesFunc(fam, ad)
|
|
if err != nil {
|
|
return e, err
|
|
}
|
|
exprs = append(exprs, e...)
|
|
}
|
|
return exprs, ad.Err()
|
|
}
|
|
}
|
|
|
|
// Marshal serializes the specified expression into a byte slice.
|
|
func Marshal(fam byte, e Any) ([]byte, error) {
|
|
return e.marshal(fam)
|
|
}
|
|
|
|
func MarshalExprData(fam byte, e Any) ([]byte, error) {
|
|
return e.marshalData(fam)
|
|
}
|
|
|
|
// Unmarshal fills an expression from the specified byte slice.
|
|
func Unmarshal(fam byte, data []byte, e Any) error {
|
|
return e.unmarshal(fam, data)
|
|
}
|
|
|
|
// exprsBytesFromName parses raw expressions bytes
|
|
// based on provided expr name
|
|
func exprsBytesFromName(fam byte, ad *netlink.AttributeDecoder, name string) ([]Any, error) {
|
|
var exprs []Any
|
|
e := exprFromName(name)
|
|
ad.Do(func(b []byte) error {
|
|
if err := Unmarshal(fam, b, e); err != nil {
|
|
return err
|
|
}
|
|
exprs = append(exprs, e)
|
|
return nil
|
|
})
|
|
return exprs, ad.Err()
|
|
}
|
|
|
|
// exprsFromBytes parses nested raw expressions bytes
|
|
// to construct nftables expressions
|
|
func exprsFromBytes(fam byte, ad *netlink.AttributeDecoder) ([]Any, error) {
|
|
var exprs []Any
|
|
|
|
ad.Do(func(b []byte) error {
|
|
ad, err := netlink.NewAttributeDecoder(b)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
ad.ByteOrder = binary.BigEndian
|
|
var name string
|
|
for ad.Next() {
|
|
switch ad.Type() {
|
|
case unix.NFTA_EXPR_NAME:
|
|
name = ad.String()
|
|
if name == "notrack" {
|
|
e := &Notrack{}
|
|
exprs = append(exprs, e)
|
|
}
|
|
case unix.NFTA_EXPR_DATA:
|
|
e := exprFromName(name)
|
|
if e == nil {
|
|
// TODO: introduce an opaque expression type so that users know
|
|
// something is here.
|
|
continue // unsupported expression type
|
|
}
|
|
ad.Do(func(b []byte) error {
|
|
if err := Unmarshal(fam, b, e); err != nil {
|
|
return err
|
|
}
|
|
// Verdict expressions are a special-case of immediate expressions, so
|
|
// if the expression is an immediate writing nothing into the verdict
|
|
// register (invalid), re-parse it as a verdict expression.
|
|
if imm, isImmediate := e.(*Immediate); isImmediate && imm.Register == unix.NFT_REG_VERDICT && len(imm.Data) == 0 {
|
|
e = &Verdict{}
|
|
if err := Unmarshal(fam, b, e); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
exprs = append(exprs, e)
|
|
return nil
|
|
})
|
|
}
|
|
}
|
|
return ad.Err()
|
|
})
|
|
return exprs, ad.Err()
|
|
}
|
|
|
|
func exprFromName(name string) Any {
|
|
var e Any
|
|
switch name {
|
|
case "ct":
|
|
e = &Ct{}
|
|
case "range":
|
|
e = &Range{}
|
|
case "meta":
|
|
e = &Meta{}
|
|
case "cmp":
|
|
e = &Cmp{}
|
|
case "counter":
|
|
e = &Counter{}
|
|
case "objref":
|
|
e = &Objref{}
|
|
case "payload":
|
|
e = &Payload{}
|
|
case "lookup":
|
|
e = &Lookup{}
|
|
case "immediate":
|
|
e = &Immediate{}
|
|
case "bitwise":
|
|
e = &Bitwise{}
|
|
case "redir":
|
|
e = &Redir{}
|
|
case "nat":
|
|
e = &NAT{}
|
|
case "limit":
|
|
e = &Limit{}
|
|
case "quota":
|
|
e = &Quota{}
|
|
case "dynset":
|
|
e = &Dynset{}
|
|
case "log":
|
|
e = &Log{}
|
|
case "exthdr":
|
|
e = &Exthdr{}
|
|
case "match":
|
|
e = &Match{}
|
|
case "target":
|
|
e = &Target{}
|
|
case "connlimit":
|
|
e = &Connlimit{}
|
|
case "queue":
|
|
e = &Queue{}
|
|
case "flow_offload":
|
|
e = &FlowOffload{}
|
|
case "reject":
|
|
e = &Reject{}
|
|
case "masq":
|
|
e = &Masq{}
|
|
case "hash":
|
|
e = &Hash{}
|
|
case "cthelper":
|
|
e = &CtHelper{}
|
|
case "synproxy":
|
|
e = &SynProxy{}
|
|
case "ctexpect":
|
|
e = &CtExpect{}
|
|
case "secmark":
|
|
e = &SecMark{}
|
|
case "cttimeout":
|
|
e = &CtTimeout{}
|
|
}
|
|
return e
|
|
}
|
|
|
|
// Any is an interface implemented by any expression type.
|
|
type Any interface {
|
|
marshal(fam byte) ([]byte, error)
|
|
marshalData(fam byte) ([]byte, error)
|
|
unmarshal(fam byte, data []byte) error
|
|
}
|
|
|
|
// MetaKey specifies which piece of meta information should be loaded. See also
|
|
// https://wiki.nftables.org/wiki-nftables/index.php/Matching_packet_metainformation
|
|
type MetaKey uint32
|
|
|
|
// Possible MetaKey values.
|
|
const (
|
|
MetaKeyLEN MetaKey = unix.NFT_META_LEN
|
|
MetaKeyPROTOCOL MetaKey = unix.NFT_META_PROTOCOL
|
|
MetaKeyPRIORITY MetaKey = unix.NFT_META_PRIORITY
|
|
MetaKeyMARK MetaKey = unix.NFT_META_MARK
|
|
MetaKeyIIF MetaKey = unix.NFT_META_IIF
|
|
MetaKeyOIF MetaKey = unix.NFT_META_OIF
|
|
MetaKeyIIFNAME MetaKey = unix.NFT_META_IIFNAME
|
|
MetaKeyOIFNAME MetaKey = unix.NFT_META_OIFNAME
|
|
MetaKeyIIFTYPE MetaKey = unix.NFT_META_IIFTYPE
|
|
MetaKeyOIFTYPE MetaKey = unix.NFT_META_OIFTYPE
|
|
MetaKeySKUID MetaKey = unix.NFT_META_SKUID
|
|
MetaKeySKGID MetaKey = unix.NFT_META_SKGID
|
|
MetaKeyNFTRACE MetaKey = unix.NFT_META_NFTRACE
|
|
MetaKeyRTCLASSID MetaKey = unix.NFT_META_RTCLASSID
|
|
MetaKeySECMARK MetaKey = unix.NFT_META_SECMARK
|
|
MetaKeyNFPROTO MetaKey = unix.NFT_META_NFPROTO
|
|
MetaKeyL4PROTO MetaKey = unix.NFT_META_L4PROTO
|
|
MetaKeyBRIIIFNAME MetaKey = unix.NFT_META_BRI_IIFNAME
|
|
MetaKeyBRIOIFNAME MetaKey = unix.NFT_META_BRI_OIFNAME
|
|
MetaKeyPKTTYPE MetaKey = unix.NFT_META_PKTTYPE
|
|
MetaKeyCPU MetaKey = unix.NFT_META_CPU
|
|
MetaKeyIIFGROUP MetaKey = unix.NFT_META_IIFGROUP
|
|
MetaKeyOIFGROUP MetaKey = unix.NFT_META_OIFGROUP
|
|
MetaKeyCGROUP MetaKey = unix.NFT_META_CGROUP
|
|
MetaKeyPRANDOM MetaKey = unix.NFT_META_PRANDOM
|
|
)
|
|
|
|
// Meta loads packet meta information for later comparisons. See also
|
|
// https://wiki.nftables.org/wiki-nftables/index.php/Matching_packet_metainformation
|
|
type Meta struct {
|
|
Key MetaKey
|
|
SourceRegister bool
|
|
Register uint32
|
|
}
|
|
|
|
func (e *Meta) marshal(fam byte) ([]byte, error) {
|
|
exprData, err := e.marshalData(fam)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return netlink.MarshalAttributes([]netlink.Attribute{
|
|
{Type: unix.NFTA_EXPR_NAME, Data: []byte("meta\x00")},
|
|
{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
|
|
})
|
|
}
|
|
|
|
func (e *Meta) marshalData(fam byte) ([]byte, error) {
|
|
var regData []byte
|
|
exprData, err := netlink.MarshalAttributes(
|
|
[]netlink.Attribute{
|
|
{Type: unix.NFTA_META_KEY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Key))},
|
|
},
|
|
)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if e.SourceRegister {
|
|
regData, err = netlink.MarshalAttributes(
|
|
[]netlink.Attribute{
|
|
{Type: unix.NFTA_META_SREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
|
|
},
|
|
)
|
|
} else {
|
|
regData, err = netlink.MarshalAttributes(
|
|
[]netlink.Attribute{
|
|
{Type: unix.NFTA_META_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
|
|
},
|
|
)
|
|
}
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
exprData = append(exprData, regData...)
|
|
return exprData, nil
|
|
}
|
|
|
|
func (e *Meta) unmarshal(fam byte, data []byte) error {
|
|
ad, err := netlink.NewAttributeDecoder(data)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
ad.ByteOrder = binary.BigEndian
|
|
for ad.Next() {
|
|
switch ad.Type() {
|
|
case unix.NFTA_META_SREG:
|
|
e.Register = ad.Uint32()
|
|
e.SourceRegister = true
|
|
case unix.NFTA_META_DREG:
|
|
e.Register = ad.Uint32()
|
|
case unix.NFTA_META_KEY:
|
|
e.Key = MetaKey(ad.Uint32())
|
|
}
|
|
}
|
|
return ad.Err()
|
|
}
|
|
|
|
// Masq (Masquerade) is a special case of SNAT, where the source address is
|
|
// automagically set to the address of the output interface. See also
|
|
// https://wiki.nftables.org/wiki-nftables/index.php/Performing_Network_Address_Translation_(NAT)#Masquerading
|
|
type Masq struct {
|
|
Random bool
|
|
FullyRandom bool
|
|
Persistent bool
|
|
ToPorts bool
|
|
RegProtoMin uint32
|
|
RegProtoMax uint32
|
|
}
|
|
|
|
const (
|
|
// NF_NAT_RANGE_PROTO_RANDOM defines flag for a random masquerade
|
|
NF_NAT_RANGE_PROTO_RANDOM = unix.NF_NAT_RANGE_PROTO_RANDOM
|
|
// NF_NAT_RANGE_PROTO_RANDOM_FULLY defines flag for a fully random masquerade
|
|
NF_NAT_RANGE_PROTO_RANDOM_FULLY = unix.NF_NAT_RANGE_PROTO_RANDOM_FULLY
|
|
// NF_NAT_RANGE_PERSISTENT defines flag for a persistent masquerade
|
|
NF_NAT_RANGE_PERSISTENT = unix.NF_NAT_RANGE_PERSISTENT
|
|
// NF_NAT_RANGE_PREFIX defines flag for a prefix masquerade
|
|
NF_NAT_RANGE_PREFIX = unix.NF_NAT_RANGE_NETMAP
|
|
// NF_NAT_RANGE_PROTO_SPECIFIED defines flag for a specified range
|
|
NF_NAT_RANGE_PROTO_SPECIFIED = unix.NF_NAT_RANGE_PROTO_SPECIFIED
|
|
)
|
|
|
|
func (e *Masq) marshal(fam byte) ([]byte, error) {
|
|
msgData, err := e.marshalData(fam)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return netlink.MarshalAttributes([]netlink.Attribute{
|
|
{Type: unix.NFTA_EXPR_NAME, Data: []byte("masq\x00")},
|
|
{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: msgData},
|
|
})
|
|
}
|
|
|
|
func (e *Masq) marshalData(fam byte) ([]byte, error) {
|
|
msgData := []byte{}
|
|
if !e.ToPorts {
|
|
flags := uint32(0)
|
|
if e.Random {
|
|
flags |= NF_NAT_RANGE_PROTO_RANDOM
|
|
}
|
|
if e.FullyRandom {
|
|
flags |= NF_NAT_RANGE_PROTO_RANDOM_FULLY
|
|
}
|
|
if e.Persistent {
|
|
flags |= NF_NAT_RANGE_PERSISTENT
|
|
}
|
|
if flags != 0 {
|
|
flagsData, err := netlink.MarshalAttributes([]netlink.Attribute{
|
|
{Type: unix.NFTA_MASQ_FLAGS, Data: binaryutil.BigEndian.PutUint32(flags)}})
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
msgData = append(msgData, flagsData...)
|
|
}
|
|
} else {
|
|
regsData, err := netlink.MarshalAttributes([]netlink.Attribute{
|
|
{Type: unix.NFTA_MASQ_REG_PROTO_MIN, Data: binaryutil.BigEndian.PutUint32(e.RegProtoMin)}})
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
msgData = append(msgData, regsData...)
|
|
if e.RegProtoMax != 0 {
|
|
regsData, err := netlink.MarshalAttributes([]netlink.Attribute{
|
|
{Type: unix.NFTA_MASQ_REG_PROTO_MAX, Data: binaryutil.BigEndian.PutUint32(e.RegProtoMax)}})
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
msgData = append(msgData, regsData...)
|
|
}
|
|
}
|
|
return msgData, nil
|
|
}
|
|
|
|
func (e *Masq) unmarshal(fam byte, data []byte) error {
|
|
ad, err := netlink.NewAttributeDecoder(data)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
ad.ByteOrder = binary.BigEndian
|
|
for ad.Next() {
|
|
switch ad.Type() {
|
|
case unix.NFTA_MASQ_REG_PROTO_MIN:
|
|
e.ToPorts = true
|
|
e.RegProtoMin = ad.Uint32()
|
|
case unix.NFTA_MASQ_REG_PROTO_MAX:
|
|
e.RegProtoMax = ad.Uint32()
|
|
case unix.NFTA_MASQ_FLAGS:
|
|
flags := ad.Uint32()
|
|
e.Persistent = (flags & NF_NAT_RANGE_PERSISTENT) != 0
|
|
e.Random = (flags & NF_NAT_RANGE_PROTO_RANDOM) != 0
|
|
e.FullyRandom = (flags & NF_NAT_RANGE_PROTO_RANDOM_FULLY) != 0
|
|
}
|
|
}
|
|
return ad.Err()
|
|
}
|
|
|
|
// CmpOp specifies which type of comparison should be performed.
|
|
type CmpOp uint32
|
|
|
|
// Possible CmpOp values.
|
|
const (
|
|
CmpOpEq CmpOp = unix.NFT_CMP_EQ
|
|
CmpOpNeq CmpOp = unix.NFT_CMP_NEQ
|
|
CmpOpLt CmpOp = unix.NFT_CMP_LT
|
|
CmpOpLte CmpOp = unix.NFT_CMP_LTE
|
|
CmpOpGt CmpOp = unix.NFT_CMP_GT
|
|
CmpOpGte CmpOp = unix.NFT_CMP_GTE
|
|
)
|
|
|
|
// Cmp compares a register with the specified data.
|
|
type Cmp struct {
|
|
Op CmpOp
|
|
Register uint32
|
|
Data []byte
|
|
}
|
|
|
|
func (e *Cmp) marshal(fam byte) ([]byte, error) {
|
|
exprData, err := e.marshalData(fam)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return netlink.MarshalAttributes([]netlink.Attribute{
|
|
{Type: unix.NFTA_EXPR_NAME, Data: []byte("cmp\x00")},
|
|
{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
|
|
})
|
|
}
|
|
|
|
func (e *Cmp) marshalData(fam byte) ([]byte, error) {
|
|
cmpData, err := netlink.MarshalAttributes([]netlink.Attribute{
|
|
{Type: unix.NFTA_DATA_VALUE, Data: e.Data},
|
|
})
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return netlink.MarshalAttributes([]netlink.Attribute{
|
|
{Type: unix.NFTA_CMP_SREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
|
|
{Type: unix.NFTA_CMP_OP, Data: binaryutil.BigEndian.PutUint32(uint32(e.Op))},
|
|
{Type: unix.NLA_F_NESTED | unix.NFTA_CMP_DATA, Data: cmpData},
|
|
})
|
|
}
|
|
|
|
func (e *Cmp) unmarshal(fam byte, data []byte) error {
|
|
ad, err := netlink.NewAttributeDecoder(data)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
ad.ByteOrder = binary.BigEndian
|
|
for ad.Next() {
|
|
switch ad.Type() {
|
|
case unix.NFTA_CMP_SREG:
|
|
e.Register = ad.Uint32()
|
|
case unix.NFTA_CMP_OP:
|
|
e.Op = CmpOp(ad.Uint32())
|
|
case unix.NFTA_CMP_DATA:
|
|
ad.Do(func(b []byte) error {
|
|
ad, err := netlink.NewAttributeDecoder(b)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
ad.ByteOrder = binary.BigEndian
|
|
if ad.Next() && ad.Type() == unix.NFTA_DATA_VALUE {
|
|
ad.Do(func(b []byte) error {
|
|
e.Data = b
|
|
return nil
|
|
})
|
|
}
|
|
return ad.Err()
|
|
})
|
|
}
|
|
}
|
|
return ad.Err()
|
|
}
|