diff --git a/expr/dup.go b/expr/dup.go new file mode 100644 index 0000000..a7e3805 --- /dev/null +++ b/expr/dup.go @@ -0,0 +1,67 @@ +// 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 + +import ( + "encoding/binary" + + "github.com/google/nftables/binaryutil" + "github.com/mdlayher/netlink" + "golang.org/x/sys/unix" +) + +type Dup struct { + RegAddr uint32 + RegDev uint32 + IsRegDevSet bool +} + +func (e *Dup) marshal() ([]byte, error) { + attrs := []netlink.Attribute{ + {Type: unix.NFTA_DUP_SREG_ADDR, Data: binaryutil.BigEndian.PutUint32(e.RegAddr)}, + } + + if e.IsRegDevSet { + attrs = append(attrs, netlink.Attribute{Type: unix.NFTA_DUP_SREG_DEV, Data: binaryutil.BigEndian.PutUint32(e.RegDev)}) + } + + data, err := netlink.MarshalAttributes(attrs) + + if err != nil { + return nil, err + } + + return netlink.MarshalAttributes([]netlink.Attribute{ + {Type: unix.NFTA_EXPR_NAME, Data: []byte("dup\x00")}, + {Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data}, + }) +} + +func (e *Dup) unmarshal(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_DUP_SREG_ADDR: + e.RegAddr = ad.Uint32() + case unix.NFTA_DUP_SREG_DEV: + e.RegDev = ad.Uint32() + } + } + return ad.Err() +} diff --git a/nftables_test.go b/nftables_test.go index 7c94e48..a735e63 100644 --- a/nftables_test.go +++ b/nftables_test.go @@ -3629,3 +3629,191 @@ func TestJHash(t *testing.T) { t.Fatal(err) } } + +func TestDup(t *testing.T) { + + // The want byte sequences come from stracing nft(8), e.g.: + // strace -f -v -x -s 2048 -eraw=sendto nft add rule filter prerouting mark set jhash ip saddr mod 2 + // + // The nft(8) command sequence was taken from: + // https://wiki.nftables.org/wiki-nftables/index.php/Quick_reference-nftables_in_10_minutes#Tcp + want := [][]byte{ + // batch begin + []byte("\x00\x00\x00\x0a"), + + // nft flush ruleset + []byte("\x00\x00\x00\x00"), + + // nft add table ip mangle + []byte("\x02\x00\x00\x00\x0b\x00\x01\x00\x6d\x61\x6e\x67\x6c\x65\x00\x00\x08\x00\x02\x00\x00\x00\x00\x00"), + + // nft add chain ip mangle base-chain { type filter hook prerouting priority 0 \; } + []byte("\x02\x00\x00\x00\x0b\x00\x01\x00\x6d\x61\x6e\x67\x6c\x65\x00\x00\x0f\x00\x03\x00\x62\x61\x73\x65\x2d\x63\x68\x61\x69\x6e\x00\x00\x14\x00\x04\x80\x08\x00\x01\x00\x00\x00\x00\x00\x08\x00\x02\x00\x00\x00\x00\x00\x0b\x00\x07\x00\x66\x69\x6c\x74\x65\x72\x00\x00"), + + // nft add rule mangle base-chain dup to 127.0.0.50 device lo + []byte("\x02\x00\x00\x00\x0b\x00\x01\x00\x6d\x61\x6e\x67\x6c\x65\x00\x00\x0f\x00\x02\x00\x62\x61\x73\x65\x2d\x63\x68\x61\x69\x6e\x00\x00\x7c\x00\x04\x80\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\x08\x00\x01\x00\x7f\x00\x00\x32\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\x02\x0c\x00\x02\x80\x08\x00\x01\x00\x01\x00\x00\x00\x20\x00\x01\x80\x08\x00\x01\x00\x64\x75\x70\x00\x14\x00\x02\x80\x08\x00\x01\x00\x00\x00\x00\x01\x08\x00\x02\x00\x00\x00\x00\x02"), + + // batch end + []byte("\x00\x00\x00\x0a"), + } + + c := &nftables.Conn{ + TestDial: func(req []netlink.Message) ([]netlink.Message, error) { + for idx, msg := range req { + b, err := msg.MarshalBinary() + if err != nil { + t.Fatal(err) + } + if len(b) < 16 { + continue + } + b = b[16:] + if len(want) == 0 { + t.Errorf("no want entry for message %d: %x", idx, b) + continue + } + if got, want := b, want[0]; !bytes.Equal(got, want) { + t.Errorf("message %d: %s", idx, linediff(nfdump(got), nfdump(want))) + } + want = want[1:] + } + return req, nil + }, + } + + c.FlushRuleset() + + mangle := c.AddTable(&nftables.Table{ + Family: nftables.TableFamilyIPv4, + Name: "mangle", + }) + + prerouting := c.AddChain(&nftables.Chain{ + Name: "base-chain", + Table: mangle, + Type: nftables.ChainTypeFilter, + Hooknum: nftables.ChainHookPrerouting, + Priority: nftables.ChainPriorityFilter, + }) + + lo, err := net.InterfaceByName("lo") + + if err != nil { + t.Fatal(err) + } + + c.AddRule(&nftables.Rule{ + Table: mangle, + Chain: prerouting, + Exprs: []expr.Any{ + // [ immediate reg 1 0x3200007f ] + &expr.Immediate{ + Register: 1, + Data: net.ParseIP("127.0.0.50").To4(), + }, + // [ immediate reg 2 0x00000001 ] + &expr.Immediate{ + Register: 2, + Data: binaryutil.NativeEndian.PutUint32(uint32(lo.Index)), + }, + // [ dup sreg_addr 1 sreg_dev 2 ] + &expr.Dup{ + RegAddr: 1, + RegDev: 2, + IsRegDevSet: true, + }, + }, + }) + + if err := c.Flush(); err != nil { + t.Fatal(err) + } +} + +func TestDupWoDev(t *testing.T) { + + // The want byte sequences come from stracing nft(8), e.g.: + // strace -f -v -x -s 2048 -eraw=sendto nft add rule filter prerouting mark set jhash ip saddr mod 2 + // + // The nft(8) command sequence was taken from: + // https://wiki.nftables.org/wiki-nftables/index.php/Quick_reference-nftables_in_10_minutes#Tcp + want := [][]byte{ + // batch begin + []byte("\x00\x00\x00\x0a"), + + // nft flush ruleset + []byte("\x00\x00\x00\x00"), + + // nft add table ip mangle + []byte("\x02\x00\x00\x00\x0b\x00\x01\x00\x6d\x61\x6e\x67\x6c\x65\x00\x00\x08\x00\x02\x00\x00\x00\x00\x00"), + + // nft add chain ip mangle base-chain { type filter hook prerouting priority 0 \; } + []byte("\x02\x00\x00\x00\x0b\x00\x01\x00\x6d\x61\x6e\x67\x6c\x65\x00\x00\x0f\x00\x03\x00\x62\x61\x73\x65\x2d\x63\x68\x61\x69\x6e\x00\x00\x14\x00\x04\x80\x08\x00\x01\x00\x00\x00\x00\x00\x08\x00\x02\x00\x00\x00\x00\x00\x0b\x00\x07\x00\x66\x69\x6c\x74\x65\x72\x00\x00"), + + // nft add rule mangle base-chain dup to 127.0.0.50 + []byte("\x02\x00\x00\x00\x0b\x00\x01\x00\x6d\x61\x6e\x67\x6c\x65\x00\x00\x0f\x00\x02\x00\x62\x61\x73\x65\x2d\x63\x68\x61\x69\x6e\x00\x00\x48\x00\x04\x80\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\x08\x00\x01\x00\x7f\x00\x00\x32\x18\x00\x01\x80\x08\x00\x01\x00\x64\x75\x70\x00\x0c\x00\x02\x80\x08\x00\x01\x00\x00\x00\x00\x01"), + + // batch end + []byte("\x00\x00\x00\x0a"), + } + + c := &nftables.Conn{ + TestDial: func(req []netlink.Message) ([]netlink.Message, error) { + for idx, msg := range req { + b, err := msg.MarshalBinary() + if err != nil { + t.Fatal(err) + } + if len(b) < 16 { + continue + } + b = b[16:] + if len(want) == 0 { + t.Errorf("no want entry for message %d: %x", idx, b) + continue + } + if got, want := b, want[0]; !bytes.Equal(got, want) { + t.Errorf("message %d: %s", idx, linediff(nfdump(got), nfdump(want))) + } + want = want[1:] + } + return req, nil + }, + } + + c.FlushRuleset() + + mangle := c.AddTable(&nftables.Table{ + Family: nftables.TableFamilyIPv4, + Name: "mangle", + }) + + prerouting := c.AddChain(&nftables.Chain{ + Name: "base-chain", + Table: mangle, + Type: nftables.ChainTypeFilter, + Hooknum: nftables.ChainHookPrerouting, + Priority: nftables.ChainPriorityFilter, + }) + + c.AddRule(&nftables.Rule{ + Table: mangle, + Chain: prerouting, + Exprs: []expr.Any{ + // [ immediate reg 1 0x3200007f ] + &expr.Immediate{ + Register: 1, + Data: net.ParseIP("127.0.0.50").To4(), + }, + // [ dup sreg_addr 1 sreg_dev 2 ] + &expr.Dup{ + RegAddr: 1, + IsRegDevSet: false, + }, + }, + }) + + if err := c.Flush(); err != nil { + t.Fatal(err) + } +}