Merge dae73eaa9c into aca62a1d00

Before this commit: the printing of a rule results in
a pointer address.

After this commit: the printing of a rules results in
a human-readable text.

Resolves: #104

Signed-off-by: Paul Greenberg <greenpau@outlook.com>

.gitignore

@@ -0,0 +1 @@
+nftables.test

README.md

@@ -21,4 +21,12 @@ the data types/API will be identified as more functionality is added.
 
 Contributions are very welcome!
 
+### Testing Changes
 
+Run the following commands to test your changes:
+
+```bash
+go test ./...
+go test -c github.com/google/nftables
+sudo ./nftables.test -test.v -run_system_tests
+```

expr/ct.go

@@ -194,3 +194,74 @@ func (c *CtHelper) unmarshal(fam byte, data []byte) error {
 	}
 	return ad.Err()
 }
+
+// From https://git.netfilter.org/libnftnl/tree/include/linux/netfilter/nf_tables.h?id=be0bae0ad31b0adb506f96de083f52a2bd0d4fbf#n1601
+// Currently not available in sys/unix
+const (
+	NFTA_CT_EXPECT_L3PROTO = 0x01
+	NFTA_CT_EXPECT_L4PROTO = 0x02
+	NFTA_CT_EXPECT_DPORT   = 0x03
+	NFTA_CT_EXPECT_TIMEOUT = 0x04
+	NFTA_CT_EXPECT_SIZE    = 0x05
+)
+
+type CtExpect struct {
+	L3Proto uint16
+	L4Proto uint8
+	DPort   uint16
+	Timeout uint32
+	Size    uint8
+}
+
+func (c *CtExpect) marshal(fam byte) ([]byte, error) {
+	exprData, err := c.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("ctexpect\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
+	})
+}
+
+func (c *CtExpect) marshalData(fam byte) ([]byte, error) {
+	// all elements except l3proto must be defined
+	// per https://git.netfilter.org/nftables/tree/doc/stateful-objects.txt?id=db70959a5ccf2952b218f51c3d529e186a5a43bb#n119
+	// from man page: l3proto is derived from the table family by default
+	exprData := []netlink.Attribute{
+		{Type: NFTA_CT_EXPECT_L4PROTO, Data: []byte{c.L4Proto}},
+		{Type: NFTA_CT_EXPECT_DPORT, Data: binaryutil.BigEndian.PutUint16(c.DPort)},
+		{Type: NFTA_CT_EXPECT_TIMEOUT, Data: binaryutil.BigEndian.PutUint32(c.Timeout)},
+		{Type: NFTA_CT_EXPECT_SIZE, Data: []byte{c.Size}},
+	}
+
+	if c.L3Proto != 0 {
+		attr := netlink.Attribute{Type: NFTA_CT_EXPECT_L3PROTO, Data: binaryutil.BigEndian.PutUint16(c.L3Proto)}
+		exprData = append(exprData, attr)
+	}
+	return netlink.MarshalAttributes(exprData)
+}
+
+func (c *CtExpect) 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 NFTA_CT_EXPECT_L3PROTO:
+			c.L3Proto = ad.Uint16()
+		case NFTA_CT_EXPECT_L4PROTO:
+			c.L4Proto = ad.Uint8()
+		case NFTA_CT_EXPECT_DPORT:
+			c.DPort = ad.Uint16()
+		case NFTA_CT_EXPECT_TIMEOUT:
+			c.Timeout = ad.Uint32()
+		case NFTA_CT_EXPECT_SIZE:
+			c.Size = ad.Uint8()
+		}
+	}
+	return ad.Err()
+}

expr/expr.go

@@ -201,6 +201,10 @@ func exprFromName(name string) Any {
 		e = &CtHelper{}
 	case "synproxy":
 		e = &SynProxy{}
+	case "ctexpect":
+		e = &CtExpect{}
+	case "secmark":
+		e = &SecMark{}
 	}
 	return e
 }

expr/secmark.go

@@ -0,0 +1,64 @@
+// Copyright 2024 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/mdlayher/netlink"
+	"golang.org/x/sys/unix"
+)
+
+// From https://git.netfilter.org/libnftnl/tree/include/linux/netfilter/nf_tables.h?id=be0bae0ad31b0adb506f96de083f52a2bd0d4fbf#n1338
+const (
+	NFTA_SECMARK_CTX = 0x01
+)
+
+type SecMark struct {
+	Ctx string
+}
+
+func (e *SecMark) marshal(fam byte) ([]byte, error) {
+	data, err := e.marshalData(fam)
+	if err != nil {
+		return nil, err
+	}
+	return netlink.MarshalAttributes([]netlink.Attribute{
+		{Type: unix.NFTA_EXPR_NAME, Data: []byte("secmark\x00")},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+	})
+}
+
+func (e *SecMark) marshalData(fam byte) ([]byte, error) {
+	attrs := []netlink.Attribute{
+		{Type: NFTA_SECMARK_CTX, Data: []byte(e.Ctx)},
+	}
+	return netlink.MarshalAttributes(attrs)
+}
+
+func (e *SecMark) 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 NFTA_SECMARK_CTX:
+			e.Ctx = ad.String()
+		}
+	}
+	return ad.Err()
+}

expr/verdict.go

@@ -24,6 +24,15 @@ import (
 	"golang.org/x/sys/unix"
 )
 
+const (
+	NFT_DROP   = 0
+	NFT_ACCEPT = 1
+	NFT_STOLEN = 2
+	NFT_QUEUE  = 3
+	NFT_REPEAT = 4
+	NFT_STOP   = 5
+)
+
 // This code assembles the verdict structure, as expected by the
 // nftables netlink API.
 // For further information, consult:
@@ -129,3 +138,37 @@ func (e *Verdict) unmarshal(fam byte, data []byte) error {
 	}
 	return ad.Err()
 }
+
+func (e *Verdict) String() string {
+	var v string
+	switch e.Kind {
+	case unix.NFT_RETURN:
+		v = "return" // -0x5
+	case unix.NFT_GOTO:
+		v = "goto" // -0x4
+	case unix.NFT_JUMP:
+		v = "jump" // NFT_JUMP = -0x3
+	case unix.NFT_BREAK:
+		v = "break" // NFT_BREAK = -0x2
+	case unix.NFT_CONTINUE:
+		v = "continue" // NFT_CONTINUE = -0x1
+	case NFT_DROP:
+		v = "drop"
+	case NFT_ACCEPT:
+		v = "accept"
+	case NFT_STOLEN:
+		v = "stolen"
+	case NFT_QUEUE:
+		v = "queue"
+	case NFT_REPEAT:
+		v = "repeat"
+	case NFT_STOP:
+		v = "stop"
+	default:
+		v = fmt.Sprintf("verdict %v", e.Kind)
+	}
+	if e.Chain != "" {
+		return v + " " + e.Chain
+	}
+	return v
+}

nftables_test.go

@@ -221,12 +221,27 @@ func TestRuleOperations(t *testing.T) {
 		expr.VerdictDrop,
 	}
 
+	wantStrings := []string{
+		"queue",
+		"accept",
+		"queue",
+		"accept",
+		"drop",
+		"drop",
+	}
+
 	for i, r := range rules {
 		rr, _ := r.Exprs[0].(*expr.Verdict)
 
 		if rr.Kind != want[i] {
 			t.Fatalf("bad verdict kind at %d", i)
 		}
+
+		if rr.String() != wantStrings[i] {
+			t.Fatalf("bad verdict string at %d: %s (received) vs. %s (expected)", i, rr.String(), wantStrings[i])
+		}
+
+		t.Logf("%s", rr)
 	}
 }
 
@@ -1383,6 +1398,68 @@ func TestCt(t *testing.T) {
 	}
 }
 
+func TestSecMarkMarshaling(t *testing.T) {
+	// Testing marshaling since secmark requires live selinux tag otherwise
+	// errors with conn.Receive: netlink receive: no such file or directory.
+	// More information available here:
+	// https://git.netfilter.org/nftables/tree/files/examples/secmark.nft?id=26d9cbefb10e6bc3765df7e9e7a4fc3b951a80f3#n6
+	want := [][]byte{
+		// batch begin
+		[]byte("\x00\x00\x00\x0a"),
+		// sudo nft add table inet filter
+		[]byte("\x01\x00\x00\x00\x0b\x00\x01\x00filter\x00\x00\x08\x00\x02\x00\x00\x00\x00\x00"),
+		// sudo nft add secmark inet filter sshtag '{ ctx "system_u:object_r:ssh_server_packet_t:s0" }'
+		[]byte("\x01\x00\x00\x00\x0b\x00\x01\x00filter\x00\x00\x0b\x00\x02\x00sshtag\x00\x00\x08\x00\x03\x00\x00\x00\x00\x080\x00\x04\x80,\x00\x01\x00system_u:object_r:ssh_server_packet_t:s0"),
+		// batch end
+		[]byte("\x00\x00\x00\x0a"),
+	}
+
+	conn, err := nftables.New(nftables.WithTestDial(
+		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
+		}))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	table := conn.AddTable(&nftables.Table{
+		Family: nftables.TableFamilyINet,
+		Name:   "filter",
+	})
+
+	sec := &nftables.NamedObj{
+		Table: table,
+		Name:  "sshtag",
+		Type:  nftables.ObjTypeSecMark,
+		Obj: &expr.SecMark{
+			Ctx: "system_u:object_r:ssh_server_packet_t:s0",
+		},
+	}
+	conn.AddObj(sec)
+
+	if err := conn.Flush(); err != nil {
+		t.Fatalf(err.Error())
+	}
+}
+
 func TestSynProxyObject(t *testing.T) {
 	conn, newNS := nftest.OpenSystemConn(t, *enableSysTests)
 	defer nftest.CleanupSystemConn(t, newNS)
@@ -1428,7 +1505,6 @@ func TestSynProxyObject(t *testing.T) {
 	conn.AddObj(syn1)
 	conn.AddObj(syn2)
 	conn.AddObj(syn3)
-
 	if err := conn.Flush(); err != nil {
 		t.Fatalf(err.Error())
 	}
@@ -1437,7 +1513,6 @@ func TestSynProxyObject(t *testing.T) {
 	if err != nil {
 		t.Errorf("c.GetObjects(table) failed: %v", err)
 	}
-
 	if got, want := len(objs), 3; got != want {
 		t.Fatalf("received %d objects, expected %d", got, want)
 	}
@@ -1481,6 +1556,74 @@ func TestSynProxyObject(t *testing.T) {
 	}
 }
 
+func TestCtExpect(t *testing.T) {
+	conn, newNS := nftest.OpenSystemConn(t, *enableSysTests)
+	defer nftest.CleanupSystemConn(t, newNS)
+	conn.FlushRuleset()
+	defer conn.FlushRuleset()
+
+	table := conn.AddTable(&nftables.Table{
+		Family: nftables.TableFamilyIPv4,
+		Name:   "filter",
+	})
+
+	cte := &nftables.NamedObj{
+		Table: table,
+		Name:  "expect",
+		Type:  nftables.ObjTypeCtExpect,
+		Obj: &expr.CtExpect{
+			L3Proto: unix.NFPROTO_IPV4,
+			L4Proto: unix.IPPROTO_TCP,
+			DPort:   53,
+			Timeout: 20,
+			Size:    100,
+		},
+	}
+
+	conn.AddObj(cte)
+	if err := conn.Flush(); err != nil {
+		t.Fatalf(err.Error())
+	}
+
+	objs, err := conn.GetNamedObjects(table)
+	if err != nil {
+		t.Errorf("c.GetObjects(table) failed: %v", err)
+	}
+
+	if got, want := len(objs), 1; got != want {
+		t.Fatalf("received %d objects, expected %d", got, want)
+	}
+
+	obj := objs[0].(*nftables.NamedObj)
+	if got, want := obj.Name, cte.Name; got != want {
+		t.Errorf("object names are not equal: got %s, want %s", got, want)
+	}
+	if got, want := obj.Type, cte.Type; got != want {
+		t.Errorf("object types are not equal: got %v, want %v", got, want)
+	}
+	if got, want := obj.Table.Name, cte.Table.Name; got != want {
+		t.Errorf("object tables are not equal: got %s, want %s", got, want)
+	}
+
+	ce1 := obj.Obj.(*expr.CtExpect)
+	ce2 := cte.Obj.(*expr.CtExpect)
+	if got, want := ce1.L3Proto, ce2.L3Proto; got != want {
+		t.Errorf("object l3proto not equal: got %d, want %d", got, want)
+	}
+	if got, want := ce1.L4Proto, ce2.L4Proto; got != want {
+		t.Errorf("object l4proto not equal: got %d, want %d", got, want)
+	}
+	if got, want := ce1.DPort, ce2.DPort; got != want {
+		t.Errorf("object dport not equal: got %d, want %d", got, want)
+	}
+	if got, want := ce1.Size, ce2.Size; got != want {
+		t.Errorf("object Size not equal: got %d, want %d", got, want)
+	}
+	if got, want := ce1.Timeout, ce2.Timeout; got != want {
+		t.Errorf("object timeout not equal: got %d, want %d", got, want)
+	}
+}
+
 func TestCtHelper(t *testing.T) {
 	conn, newNS := nftest.OpenSystemConn(t, *enableSysTests)
 	defer nftest.CleanupSystemConn(t, newNS)

nftables_test.sh

@@ -0,0 +1,3 @@
+go test ./...
+go test -c github.com/google/nftables
+sudo ./nftables.test -test.v -run_system_tests

obj.go

@@ -54,9 +54,9 @@ var objByObjTypeMagic = map[ObjType]string{
 	ObjTypeCtHelper:  "cthelper",
 	ObjTypeTunnel:    "tunnel",    // not implemented in expr
 	ObjTypeCtTimeout: "cttimeout", // not implemented in expr
-	ObjTypeSecMark:   "secmark",   // not implemented in expr
+	ObjTypeSecMark:   "secmark",
-	ObjTypeCtExpect:  "ctexpect",  // not implemented in expr
+	ObjTypeCtExpect:  "ctexpect",
-	ObjTypeSynProxy:  "synproxy",  // not implemented in expr
+	ObjTypeSynProxy:  "synproxy",
 }
 
 // Obj represents a netfilter stateful object. See also