add exprs and test for TCP MSS clamping

This commit is contained in:
Michael Stapelberg 2018-10-22 09:22:02 +02:00
parent efc2089755
commit 9ac63cb282
5 changed files with 422 additions and 4 deletions

65
expr/bitwise.go Normal file
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@ -0,0 +1,65 @@
// 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 (
"fmt"
"github.com/google/nftables/binaryutil"
"github.com/mdlayher/netlink"
"golang.org/x/sys/unix"
)
type Bitwise struct {
SourceRegister uint32
DestRegister uint32
Len uint32
Mask []byte
Xor []byte
}
func (e *Bitwise) marshal() ([]byte, error) {
mask, err := netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_DATA_VALUE, Data: e.Mask},
})
if err != nil {
return nil, err
}
xor, err := netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_DATA_VALUE, Data: e.Xor},
})
if err != nil {
return nil, err
}
data, err := netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_BITWISE_SREG, Data: binaryutil.BigEndian.PutUint32(e.SourceRegister)},
{Type: unix.NFTA_BITWISE_DREG, Data: binaryutil.BigEndian.PutUint32(e.DestRegister)},
{Type: unix.NFTA_BITWISE_LEN, Data: binaryutil.BigEndian.PutUint32(e.Len)},
{Type: unix.NLA_F_NESTED | unix.NFTA_BITWISE_MASK, Data: mask},
{Type: unix.NLA_F_NESTED | unix.NFTA_BITWISE_XOR, Data: xor},
})
if err != nil {
return nil, err
}
return netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_EXPR_NAME, Data: []byte("bitwise\x00")},
{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
})
}
func (e *Bitwise) unmarshal(data []byte) error {
return fmt.Errorf("not yet implemented")
}

59
expr/byteorder.go Normal file
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@ -0,0 +1,59 @@
// 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 (
"fmt"
"github.com/google/nftables/binaryutil"
"github.com/mdlayher/netlink"
"golang.org/x/sys/unix"
)
type ByteorderOp uint32
const (
ByteorderNtoh ByteorderOp = unix.NFT_BYTEORDER_NTOH
ByteorderHton ByteorderOp = unix.NFT_BYTEORDER_HTON
)
type Byteorder struct {
SourceRegister uint32
DestRegister uint32
Op ByteorderOp
Len uint32
Size uint32
}
func (e *Byteorder) marshal() ([]byte, error) {
data, err := netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_BYTEORDER_SREG, Data: binaryutil.BigEndian.PutUint32(e.SourceRegister)},
{Type: unix.NFTA_BYTEORDER_DREG, Data: binaryutil.BigEndian.PutUint32(e.DestRegister)},
{Type: unix.NFTA_BYTEORDER_OP, Data: binaryutil.BigEndian.PutUint32(uint32(e.Op))},
{Type: unix.NFTA_BYTEORDER_LEN, Data: binaryutil.BigEndian.PutUint32(e.Len)},
{Type: unix.NFTA_BYTEORDER_SIZE, Data: binaryutil.BigEndian.PutUint32(e.Size)},
})
if err != nil {
return nil, err
}
return netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_EXPR_NAME, Data: []byte("byteorder\x00")},
{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
})
}
func (e *Byteorder) unmarshal(data []byte) error {
return fmt.Errorf("not yet implemented")
}

64
expr/exthdr.go Normal file
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@ -0,0 +1,64 @@
// 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 (
"fmt"
"github.com/google/nftables/binaryutil"
"github.com/mdlayher/netlink"
"golang.org/x/sys/unix"
)
type ExthdrOp uint32
const (
ExthdrOpIpv6 ExthdrOp = unix.NFT_EXTHDR_OP_IPV6
ExthdrOpTcpopt ExthdrOp = unix.NFT_EXTHDR_OP_TCPOPT
)
type Exthdr struct {
DestRegister uint32
Type uint8
Offset uint32
Len uint32
Flags uint32
Op ExthdrOp
SourceRegister uint32
}
func (e *Exthdr) marshal() ([]byte, error) {
data, err := netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_EXTHDR_SREG, Data: binaryutil.BigEndian.PutUint32(e.SourceRegister)},
{Type: unix.NFTA_EXTHDR_TYPE, Data: []byte{e.Type}},
{Type: unix.NFTA_EXTHDR_OFFSET, Data: binaryutil.BigEndian.PutUint32(e.Offset)},
{Type: unix.NFTA_EXTHDR_LEN, Data: binaryutil.BigEndian.PutUint32(e.Len)},
// TODO: these fields seem to be conditional?
//{Type: unix.NFTA_EXTHDR_DREG, Data: binaryutil.BigEndian.PutUint32(e.DestRegister)},
//{Type: unix.NFTA_EXTHDR_FLAGS, Data: binaryutil.BigEndian.PutUint32(e.Flags)},
{Type: unix.NFTA_EXTHDR_OP, Data: binaryutil.BigEndian.PutUint32(uint32(e.Op))},
})
if err != nil {
return nil, err
}
return netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_EXPR_NAME, Data: []byte("exthdr\x00")},
{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
})
}
func (e *Exthdr) unmarshal(data []byte) error {
return fmt.Errorf("not yet implemented")
}

55
expr/rt.go Normal file
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@ -0,0 +1,55 @@
// 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 (
"fmt"
"github.com/google/nftables/binaryutil"
"github.com/mdlayher/netlink"
"golang.org/x/sys/unix"
)
type RtKey uint32
const (
RtClassid RtKey = unix.NFT_RT_CLASSID
RtNexthop4 RtKey = unix.NFT_RT_NEXTHOP4
RtNexthop6 RtKey = unix.NFT_RT_NEXTHOP6
RtTCPMSS RtKey = unix.NFT_RT_TCPMSS
)
type Rt struct {
Register uint32
Key RtKey
}
func (e *Rt) marshal() ([]byte, error) {
data, err := netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_RT_KEY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Key))},
{Type: unix.NFTA_RT_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
})
if err != nil {
return nil, err
}
return netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_EXPR_NAME, Data: []byte("rt\x00")},
{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
})
}
func (e *Rt) unmarshal(data []byte) error {
return fmt.Errorf("not yet implemented")
}

View File

@ -16,7 +16,9 @@ package nftables_test
import (
"bytes"
"fmt"
"net"
"strings"
"testing"
"github.com/google/nftables"
@ -26,6 +28,46 @@ import (
"golang.org/x/sys/unix"
)
// nfdump returns a hexdump of 4 bytes per line (like nft --debug=all), allowing
// users to make sense of large byte literals more easily.
func nfdump(b []byte) string {
var buf bytes.Buffer
i := 0
for ; i < len(b); i += 4 {
// TODO: show printable characters as ASCII
fmt.Fprintf(&buf, "%02x %02x %02x %02x\n",
b[i],
b[i+1],
b[i+2],
b[i+3])
}
for ; i < len(b); i++ {
fmt.Fprintf(&buf, "%02x ", b[i])
}
return buf.String()
}
// linediff returns a side-by-side diff of two nfdump() return values, flagging
// lines which are not equal with an exclamation point prefix.
func linediff(a, b string) string {
var buf bytes.Buffer
fmt.Fprintf(&buf, "got -- want\n")
linesA := strings.Split(a, "\n")
linesB := strings.Split(b, "\n")
for idx, lineA := range linesA {
if idx >= len(linesB) {
break
}
lineB := linesB[idx]
prefix := "! "
if lineA == lineB {
prefix = " "
}
fmt.Fprintf(&buf, "%s%s -- %s\n", prefix, lineA, lineB)
}
return buf.String()
}
func ifname(n string) []byte {
b := make([]byte, 16)
copy(b, []byte(n+"\x00"))
@ -75,7 +117,7 @@ func TestConfigureNAT(t *testing.T) {
continue
}
if got, want := b, want[0]; !bytes.Equal(got, want) {
t.Errorf("message %d: got %x, want %x", idx, got, want)
t.Errorf("message %d: %s", idx, linediff(nfdump(got), nfdump(want)))
}
want = want[1:]
}
@ -284,7 +326,7 @@ func TestGetRule(t *testing.T) {
continue
}
if got, want := b, want[0]; !bytes.Equal(got, want) {
t.Errorf("message %d: got %#v, want %#v", idx, got, want)
t.Errorf("message %d: %s", idx, linediff(nfdump(got), nfdump(want)))
}
want = want[1:]
}
@ -363,7 +405,7 @@ func TestAddCounter(t *testing.T) {
continue
}
if got, want := b, want[0]; !bytes.Equal(got, want) {
t.Errorf("message %d: got %x, want %x", idx, got, want)
t.Errorf("message %d: %s", idx, linediff(nfdump(got), nfdump(want)))
}
want = want[1:]
}
@ -426,7 +468,7 @@ func TestGetObjReset(t *testing.T) {
continue
}
if got, want := b, want[0]; !bytes.Equal(got, want) {
t.Errorf("message %d: got %#v, want %#v", idx, got, want)
t.Errorf("message %d: %s", idx, linediff(nfdump(got), nfdump(want)))
}
want = want[1:]
}
@ -468,3 +510,136 @@ func TestGetObjReset(t *testing.T) {
t.Errorf("unexpected number of bytes: got %d, want %d", got, want)
}
}
func TestConfigureClamping(t *testing.T) {
// The want byte sequences come from stracing nft(8), e.g.:
// strace -f -v -x -s 2048 -eraw=sendto nft add table ip nat
//
// The nft(8) command sequence was taken from:
// https://wiki.nftables.org/wiki-nftables/index.php/Mangle_TCP_options
want := [][]byte{
// batch begin
[]byte("\x00\x00\x00\x0a"),
// nft flush ruleset
[]byte("\x00\x00\x00\x00"),
// nft add table ip filter
[]byte("\x02\x00\x00\x00\x0b\x00\x01\x00\x66\x69\x6c\x74\x65\x72\x00\x00\x08\x00\x02\x00\x00\x00\x00\x00"),
// nft add chain filter forward '{' type filter hook forward priority 0 \; '}'
[]byte("\x02\x00\x00\x00\x0b\x00\x01\x00\x66\x69\x6c\x74\x65\x72\x00\x00\x0c\x00\x03\x00\x66\x6f\x72\x77\x61\x72\x64\x00\x14\x00\x04\x80\x08\x00\x01\x00\x00\x00\x00\x02\x08\x00\x02\x00\x00\x00\x00\x00\x0b\x00\x07\x00\x66\x69\x6c\x74\x65\x72\x00\x00"),
// nft add rule ip filter forward oifname uplink0 tcp flags syn tcp option maxseg size set rt mtu
[]byte("\x02\x00\x00\x00\x0b\x00\x01\x00\x66\x69\x6c\x74\x65\x72\x00\x00\x0c\x00\x02\x00\x66\x6f\x72\x77\x61\x72\x64\x00\xf0\x01\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\x07\x08\x00\x01\x00\x00\x00\x00\x01\x38\x00\x01\x80\x08\x00\x01\x00\x63\x6d\x70\x00\x2c\x00\x02\x80\x08\x00\x01\x00\x00\x00\x00\x01\x08\x00\x02\x00\x00\x00\x00\x00\x18\x00\x03\x80\x14\x00\x01\x00\x75\x70\x6c\x69\x6e\x6b\x30\x00\x00\x00\x00\x00\x00\x00\x00\x00\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\x0d\x08\x00\x04\x00\x00\x00\x00\x01\x44\x00\x01\x80\x0c\x00\x01\x00\x62\x69\x74\x77\x69\x73\x65\x00\x34\x00\x02\x80\x08\x00\x01\x00\x00\x00\x00\x01\x08\x00\x02\x00\x00\x00\x00\x01\x08\x00\x03\x00\x00\x00\x00\x01\x0c\x00\x04\x80\x05\x00\x01\x00\x02\x00\x00\x00\x0c\x00\x05\x80\x05\x00\x01\x00\x00\x00\x00\x00\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\x01\x0c\x00\x03\x80\x05\x00\x01\x00\x00\x00\x00\x00\x20\x00\x01\x80\x07\x00\x01\x00\x72\x74\x00\x00\x14\x00\x02\x80\x08\x00\x02\x00\x00\x00\x00\x03\x08\x00\x01\x00\x00\x00\x00\x01\x40\x00\x01\x80\x0e\x00\x01\x00\x62\x79\x74\x65\x6f\x72\x64\x65\x72\x00\x00\x00\x2c\x00\x02\x80\x08\x00\x01\x00\x00\x00\x00\x01\x08\x00\x02\x00\x00\x00\x00\x01\x08\x00\x03\x00\x00\x00\x00\x01\x08\x00\x04\x00\x00\x00\x00\x02\x08\x00\x05\x00\x00\x00\x00\x02\x3c\x00\x01\x80\x0b\x00\x01\x00\x65\x78\x74\x68\x64\x72\x00\x00\x2c\x00\x02\x80\x08\x00\x07\x00\x00\x00\x00\x01\x05\x00\x02\x00\x02\x00\x00\x00\x08\x00\x03\x00\x00\x00\x00\x02\x08\x00\x04\x00\x00\x00\x00\x02\x08\x00\x06\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()
filter := c.AddTable(&nftables.Table{
Family: nftables.TableFamilyIPv4,
Name: "filter",
})
forward := c.AddChain(&nftables.Chain{
Name: "forward",
Table: filter,
Type: nftables.ChainTypeFilter,
Hooknum: nftables.ChainHookForward,
Priority: nftables.ChainPriorityFilter,
})
c.AddRule(&nftables.Rule{
Table: filter,
Chain: forward,
Exprs: []expr.Any{
// [ meta load oifname => reg 1 ]
&expr.Meta{Key: expr.MetaKeyOIFNAME, Register: 1},
// [ cmp eq reg 1 0x30707070 0x00000000 0x00000000 0x00000000 ]
&expr.Cmp{
Op: expr.CmpOpEq,
Register: 1,
Data: ifname("uplink0"),
},
// [ meta load l4proto => reg 1 ]
&expr.Meta{Key: expr.MetaKeyL4PROTO, Register: 1},
// [ cmp eq reg 1 0x00000006 ]
&expr.Cmp{
Op: expr.CmpOpEq,
Register: 1,
Data: []byte{unix.IPPROTO_TCP},
},
// [ payload load 1b @ transport header + 13 => reg 1 ]
&expr.Payload{
DestRegister: 1,
Base: expr.PayloadBaseTransportHeader,
Offset: 13, // TODO
Len: 1, // TODO
},
// [ bitwise reg 1 = (reg=1 & 0x00000002 ) ^ 0x00000000 ]
&expr.Bitwise{
DestRegister: 1,
SourceRegister: 1,
Len: 1,
Mask: []byte{0x02},
Xor: []byte{0x00},
},
// [ cmp neq reg 1 0x00000000 ]
&expr.Cmp{
Op: expr.CmpOpNeq,
Register: 1,
Data: []byte{0x00},
},
// [ rt load tcpmss => reg 1 ]
&expr.Rt{
Register: 1,
Key: expr.RtTCPMSS,
},
// [ byteorder reg 1 = hton(reg 1, 2, 2) ]
&expr.Byteorder{
DestRegister: 1,
SourceRegister: 1,
Op: expr.ByteorderHton,
Len: 2,
Size: 2,
},
// [ exthdr write tcpopt reg 1 => 2b @ 2 + 2 ]
&expr.Exthdr{
SourceRegister: 1,
Type: 2, // TODO
Offset: 2,
Len: 2,
Op: expr.ExthdrOpTcpopt,
},
},
})
if err := c.Flush(); err != nil {
t.Fatal(err)
}
}