268 lines
7.3 KiB
Go
268 lines
7.3 KiB
Go
// Copyright 2018 Google LLC. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package expr
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import (
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"encoding/binary"
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"github.com/google/nftables/binaryutil"
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"github.com/mdlayher/netlink"
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"golang.org/x/sys/unix"
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)
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// CtKey specifies which piece of conntrack information should be loaded. See
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// also https://wiki.nftables.org/wiki-nftables/index.php/Matching_connection_tracking_stateful_metainformation
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type CtKey uint32
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// Possible CtKey values.
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const (
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CtKeySTATE CtKey = unix.NFT_CT_STATE
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CtKeyDIRECTION CtKey = unix.NFT_CT_DIRECTION
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CtKeySTATUS CtKey = unix.NFT_CT_STATUS
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CtKeyMARK CtKey = unix.NFT_CT_MARK
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CtKeySECMARK CtKey = unix.NFT_CT_SECMARK
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CtKeyEXPIRATION CtKey = unix.NFT_CT_EXPIRATION
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CtKeyHELPER CtKey = unix.NFT_CT_HELPER
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CtKeyL3PROTOCOL CtKey = unix.NFT_CT_L3PROTOCOL
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CtKeySRC CtKey = unix.NFT_CT_SRC
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CtKeyDST CtKey = unix.NFT_CT_DST
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CtKeyPROTOCOL CtKey = unix.NFT_CT_PROTOCOL
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CtKeyPROTOSRC CtKey = unix.NFT_CT_PROTO_SRC
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CtKeyPROTODST CtKey = unix.NFT_CT_PROTO_DST
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CtKeyLABELS CtKey = unix.NFT_CT_LABELS
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CtKeyPKTS CtKey = unix.NFT_CT_PKTS
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CtKeyBYTES CtKey = unix.NFT_CT_BYTES
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CtKeyAVGPKT CtKey = unix.NFT_CT_AVGPKT
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CtKeyZONE CtKey = unix.NFT_CT_ZONE
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CtKeyEVENTMASK CtKey = unix.NFT_CT_EVENTMASK
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// https://sources.debian.org/src//nftables/0.9.8-3/src/ct.c/?hl=39#L39
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CtStateBitINVALID uint32 = 1
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CtStateBitESTABLISHED uint32 = 2
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CtStateBitRELATED uint32 = 4
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CtStateBitNEW uint32 = 8
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CtStateBitUNTRACKED uint32 = 64
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)
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// Ct defines type for NFT connection tracking
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type Ct struct {
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Register uint32
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SourceRegister bool
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Key CtKey
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Direction uint32
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}
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func (e *Ct) marshal(fam byte) ([]byte, error) {
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exprData, err := e.marshalData(fam)
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if err != nil {
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return nil, err
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}
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return netlink.MarshalAttributes([]netlink.Attribute{
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{Type: unix.NFTA_EXPR_NAME, Data: []byte("ct\x00")},
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{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
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})
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}
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func (e *Ct) marshalData(fam byte) ([]byte, error) {
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var regData []byte
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exprData, err := netlink.MarshalAttributes(
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[]netlink.Attribute{
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{Type: unix.NFTA_CT_KEY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Key))},
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},
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)
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if err != nil {
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return nil, err
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}
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if e.SourceRegister {
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regData, err = netlink.MarshalAttributes(
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[]netlink.Attribute{
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{Type: unix.NFTA_CT_SREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
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},
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)
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} else {
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regData, err = netlink.MarshalAttributes(
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[]netlink.Attribute{
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{Type: unix.NFTA_CT_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
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},
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)
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}
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if err != nil {
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return nil, err
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}
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exprData = append(exprData, regData...)
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switch e.Key {
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case CtKeySRC, CtKeyDST, CtKeyPROTOSRC, CtKeyPROTODST:
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regData, err = netlink.MarshalAttributes(
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[]netlink.Attribute{
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{Type: unix.NFTA_CT_DIRECTION, Data: binaryutil.BigEndian.PutUint32(e.Direction)},
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},
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)
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if err != nil {
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return nil, err
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}
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exprData = append(exprData, regData...)
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}
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return exprData, nil
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}
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func (e *Ct) unmarshal(fam byte, data []byte) error {
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ad, err := netlink.NewAttributeDecoder(data)
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if err != nil {
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return err
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}
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ad.ByteOrder = binary.BigEndian
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for ad.Next() {
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switch ad.Type() {
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case unix.NFTA_CT_KEY:
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e.Key = CtKey(ad.Uint32())
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case unix.NFTA_CT_DREG:
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e.Register = ad.Uint32()
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case unix.NFTA_CT_DIRECTION:
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e.Direction = ad.Uint32()
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}
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}
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return ad.Err()
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}
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type CtHelper struct {
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Name string
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L3Proto uint16
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L4Proto uint8
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}
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func (c *CtHelper) marshal(fam byte) ([]byte, error) {
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exprData, err := c.marshalData(fam)
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if err != nil {
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return nil, err
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}
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return netlink.MarshalAttributes([]netlink.Attribute{
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{Type: unix.NFTA_EXPR_NAME, Data: []byte("cthelper\x00")},
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{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
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})
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}
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func (c *CtHelper) marshalData(fam byte) ([]byte, error) {
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exprData := []netlink.Attribute{
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{Type: unix.NFTA_CT_HELPER_NAME, Data: []byte(c.Name)},
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}
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if c.L3Proto != 0 {
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exprData = append(exprData, netlink.Attribute{
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Type: unix.NFTA_CT_HELPER_L3PROTO, Data: binaryutil.BigEndian.PutUint16(c.L3Proto),
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})
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}
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if c.L4Proto != 0 {
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exprData = append(exprData, netlink.Attribute{
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Type: unix.NFTA_CT_HELPER_L4PROTO, Data: []byte{c.L4Proto},
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})
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}
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return netlink.MarshalAttributes(exprData)
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}
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func (c *CtHelper) unmarshal(fam byte, data []byte) error {
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ad, err := netlink.NewAttributeDecoder(data)
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if err != nil {
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return err
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}
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ad.ByteOrder = binary.BigEndian
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for ad.Next() {
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switch ad.Type() {
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case unix.NFTA_CT_HELPER_NAME:
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c.Name = ad.String()
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case unix.NFTA_CT_HELPER_L3PROTO:
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c.L3Proto = ad.Uint16()
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case unix.NFTA_CT_HELPER_L4PROTO:
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c.L4Proto = ad.Uint8()
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}
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}
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return ad.Err()
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}
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// From https://git.netfilter.org/libnftnl/tree/include/linux/netfilter/nf_tables.h?id=be0bae0ad31b0adb506f96de083f52a2bd0d4fbf#n1601
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// Currently not available in sys/unix
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const (
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NFTA_CT_EXPECT_L3PROTO = 0x01
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NFTA_CT_EXPECT_L4PROTO = 0x02
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NFTA_CT_EXPECT_DPORT = 0x03
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NFTA_CT_EXPECT_TIMEOUT = 0x04
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NFTA_CT_EXPECT_SIZE = 0x05
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)
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type CtExpect struct {
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L3Proto uint16
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L4Proto uint8
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DPort uint16
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Timeout uint32
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Size uint8
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}
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func (c *CtExpect) marshal(fam byte) ([]byte, error) {
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exprData, err := c.marshalData(fam)
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if err != nil {
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return nil, err
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}
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return netlink.MarshalAttributes([]netlink.Attribute{
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{Type: unix.NFTA_EXPR_NAME, Data: []byte("ctexpect\x00")},
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{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
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})
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}
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func (c *CtExpect) marshalData(fam byte) ([]byte, error) {
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// all elements except l3proto must be defined
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// per https://git.netfilter.org/nftables/tree/doc/stateful-objects.txt?id=db70959a5ccf2952b218f51c3d529e186a5a43bb#n119
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// from man page: l3proto is derived from the table family by default
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exprData := []netlink.Attribute{
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{Type: NFTA_CT_EXPECT_L4PROTO, Data: []byte{c.L4Proto}},
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{Type: NFTA_CT_EXPECT_DPORT, Data: binaryutil.BigEndian.PutUint16(c.DPort)},
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{Type: NFTA_CT_EXPECT_TIMEOUT, Data: binaryutil.BigEndian.PutUint32(c.Timeout)},
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{Type: NFTA_CT_EXPECT_SIZE, Data: []byte{c.Size}},
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}
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if c.L3Proto != 0 {
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attr := netlink.Attribute{Type: NFTA_CT_EXPECT_L3PROTO, Data: binaryutil.BigEndian.PutUint16(c.L3Proto)}
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exprData = append(exprData, attr)
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}
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return netlink.MarshalAttributes(exprData)
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}
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func (c *CtExpect) unmarshal(fam byte, data []byte) error {
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ad, err := netlink.NewAttributeDecoder(data)
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if err != nil {
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return err
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}
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ad.ByteOrder = binary.BigEndian
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for ad.Next() {
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switch ad.Type() {
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case NFTA_CT_EXPECT_L3PROTO:
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c.L3Proto = ad.Uint16()
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case NFTA_CT_EXPECT_L4PROTO:
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c.L4Proto = ad.Uint8()
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case NFTA_CT_EXPECT_DPORT:
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c.DPort = ad.Uint16()
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case NFTA_CT_EXPECT_TIMEOUT:
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c.Timeout = ad.Uint32()
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case NFTA_CT_EXPECT_SIZE:
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c.Size = ad.Uint8()
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}
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}
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return ad.Err()
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}
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