Michael Stapelberg
parent
b0a2c473e0
commit
c5bb71b2cf
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@ -0,0 +1,71 @@
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// 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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type Redir struct {
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RegisterProtoMin uint32
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RegisterProtoMax uint32
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Flags uint32
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}
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func (e *Redir) marshal() ([]byte, error) {
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var attrs []netlink.Attribute
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if e.RegisterProtoMin > 0 {
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attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_REDIR_REG_PROTO_MIN, Data: binaryutil.BigEndian.PutUint32(e.RegisterProtoMin)})
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}
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if e.RegisterProtoMax > 0 {
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attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_REDIR_REG_PROTO_MAX, Data: binaryutil.BigEndian.PutUint32(e.RegisterProtoMax)})
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}
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if e.Flags > 0 {
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attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_REDIR_FLAGS, Data: binaryutil.BigEndian.PutUint32(e.Flags)})
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}
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data, err := netlink.MarshalAttributes(attrs)
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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("redir\x00")},
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{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
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})
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}
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func (e *Redir) unmarshal(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_REDIR_REG_PROTO_MIN:
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e.RegisterProtoMin = ad.Uint32()
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case unix.NFTA_REDIR_REG_PROTO_MAX:
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e.RegisterProtoMax = ad.Uint32()
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case unix.NFTA_REDIR_FLAGS:
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e.Flags = 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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105
nftables_test.go
105
nftables_test.go
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@ -1240,3 +1240,108 @@ func TestGetRuleLookupVerdictImmediate(t *testing.T) {
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t.Errorf("verdict expr = %+v, wanted %+v", imm, want)
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}
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}
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func TestConfigureNATRedirect(t *testing.T) {
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// The want byte sequences come from stracing nft(8), e.g.:
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// strace -f -v -x -s 2048 -eraw=sendto nft add table ip nat
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//
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// The nft(8) command sequence was taken from:
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// https://wiki.nftables.org/wiki-nftables/index.php/Performing_Network_Address_Translation_(NAT)
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want := [][]byte{
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// batch begin
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[]byte("\x00\x00\x00\x0a"),
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// nft flush ruleset
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[]byte("\x00\x00\x00\x00"),
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// nft add table ip nat
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[]byte("\x02\x00\x00\x00\x08\x00\x01\x00\x6e\x61\x74\x00\x08\x00\x02\x00\x00\x00\x00\x00"),
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// nft add chain nat prerouting '{' type nat hook prerouting priority 0 \; '}'
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[]byte("\x02\x00\x00\x00\x08\x00\x01\x00\x6e\x61\x74\x00\x0f\x00\x03\x00\x70\x72\x65\x72\x6f\x75\x74\x69\x6e\x67\x00\x00\x14\x00\x04\x80\x08\x00\x01\x00\x00\x00\x00\x00\x08\x00\x02\x00\x00\x00\x00\x00\x08\x00\x07\x00\x6e\x61\x74\x00"),
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// nft add rule nat prerouting tcp dport 22 redirect to 2222
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[]byte("\x02\x00\x00\x00\x08\x00\x01\x00\x6e\x61\x74\x00\x0f\x00\x02\x00\x70\x72\x65\x72\x6f\x75\x74\x69\x6e\x67\x00\x00\xfc\x00\x04\x80\x24\x00\x01\x80\x09\x00\x01\x00\x6d\x65\x74\x61\x00\x00\x00\x00\x14\x00\x02\x80\x08\x00\x02\x00\x00\x00\x00\x10\x08\x00\x01\x00\x00\x00\x00\x01\x2c\x00\x01\x80\x08\x00\x01\x00\x63\x6d\x70\x00\x20\x00\x02\x80\x08\x00\x01\x00\x00\x00\x00\x01\x08\x00\x02\x00\x00\x00\x00\x00\x0c\x00\x03\x80\x05\x00\x01\x00\x06\x00\x00\x00\x34\x00\x01\x80\x0c\x00\x01\x00\x70\x61\x79\x6c\x6f\x61\x64\x00\x24\x00\x02\x80\x08\x00\x01\x00\x00\x00\x00\x01\x08\x00\x02\x00\x00\x00\x00\x02\x08\x00\x03\x00\x00\x00\x00\x02\x08\x00\x04\x00\x00\x00\x00\x02\x2c\x00\x01\x80\x08\x00\x01\x00\x63\x6d\x70\x00\x20\x00\x02\x80\x08\x00\x01\x00\x00\x00\x00\x01\x08\x00\x02\x00\x00\x00\x00\x00\x0c\x00\x03\x80\x06\x00\x01\x00\x00\x16\x00\x00\x2c\x00\x01\x80\x0e\x00\x01\x00\x69\x6d\x6d\x65\x64\x69\x61\x74\x65\x00\x00\x00\x18\x00\x02\x80\x08\x00\x01\x00\x00\x00\x00\x01\x0c\x00\x02\x80\x06\x00\x01\x00\x08\xae\x00\x00\x1c\x00\x01\x80\x0a\x00\x01\x00\x72\x65\x64\x69\x72\x00\x00\x00\x0c\x00\x02\x80\x08\x00\x01\x00\x00\x00\x00\x01"),
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// batch end
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[]byte("\x00\x00\x00\x0a"),
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}
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c := &nftables.Conn{
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TestDial: func(req []netlink.Message) ([]netlink.Message, error) {
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for idx, msg := range req {
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b, err := msg.MarshalBinary()
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if err != nil {
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t.Fatal(err)
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}
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if len(b) < 16 {
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continue
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}
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b = b[16:]
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if len(want) == 0 {
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t.Errorf("no want entry for message %d: %x", idx, b)
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continue
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}
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if got, want := b, want[0]; !bytes.Equal(got, want) {
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t.Errorf("message %d: %s", idx, linediff(nfdump(got), nfdump(want)))
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}
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want = want[1:]
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}
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return req, nil
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},
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}
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c.FlushRuleset()
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nat := c.AddTable(&nftables.Table{
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Family: nftables.TableFamilyIPv4,
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Name: "nat",
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})
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prerouting := c.AddChain(&nftables.Chain{
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Name: "prerouting",
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Hooknum: nftables.ChainHookPrerouting,
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Priority: nftables.ChainPriorityFilter,
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Table: nat,
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Type: nftables.ChainTypeNAT,
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})
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c.AddRule(&nftables.Rule{
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Table: nat,
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Chain: prerouting,
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Exprs: []expr.Any{
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// [ meta load l4proto => reg 1 ]
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&expr.Meta{Key: expr.MetaKeyL4PROTO, Register: 1},
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// [ cmp eq reg 1 0x00000006 ]
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&expr.Cmp{
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Op: expr.CmpOpEq,
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Register: 1,
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Data: []byte{unix.IPPROTO_TCP},
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},
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// [ payload load 2b @ transport header + 2 => reg 1 ]
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&expr.Payload{
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DestRegister: 1,
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Base: expr.PayloadBaseTransportHeader,
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Offset: 2, // TODO
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Len: 2, // TODO
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},
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// [ cmp eq reg 1 0x00001600 ]
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&expr.Cmp{
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Op: expr.CmpOpEq,
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Register: 1,
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Data: []byte{0x00, 0x16},
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},
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// [ immediate reg 1 0x0000ae08 ]
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&expr.Immediate{
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Register: 1,
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Data: binaryutil.BigEndian.PutUint16(2222),
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},
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// [ redir proto_min reg 1 ]
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&expr.Redir{
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RegisterProtoMin: 1,
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},
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},
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})
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if err := c.Flush(); err != nil {
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t.Fatal(err)
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}
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}
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