router: add test cases for malformed paths (#4572)

Add test cases for checks added in #4556; - invalid (non-peer) segments with a single hop field - hop field pointer not pointing into current segment
scionproto · Jul 15, 2024 · eab1cab · eab1cab
1 parent db65d82
commit eab1cab
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diff --git a/tools/braccept/cases/BUILD.bazel b/tools/braccept/cases/BUILD.bazel
@@ -11,6 +11,7 @@ go_library(
         "doc.go",
         "internal_to_child.go",
         "jumbo.go",
+        "malformed_path.go",
         "onehop.go",
         "parent_to_child.go",
         "parent_to_internal.go",

diff --git a/tools/braccept/cases/malformed_path.go b/tools/braccept/cases/malformed_path.go
@@ -0,0 +1,259 @@
+// Copyright 2024 SCION Association
+//
+// 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 cases
+
+import (
+	"hash"
+	"net"
+	"path/filepath"
+	"time"
+
+	"github.com/google/gopacket"
+	"github.com/google/gopacket/layers"
+
+	"github.com/scionproto/scion/pkg/addr"
+	"github.com/scionproto/scion/pkg/private/util"
+	"github.com/scionproto/scion/pkg/slayers"
+	"github.com/scionproto/scion/pkg/slayers/path"
+	"github.com/scionproto/scion/pkg/slayers/path/scion"
+	"github.com/scionproto/scion/tools/braccept/runner"
+)
+
+// MalformedPathSingletonSegment tests invalid (non-peer) path segments with a single hop field.
+// In this test case, an invalid single-hop core segment is included in an otherwise valid path.
+// This is invalid and the semantics of this are consequently undefined; in our implementation of
+// the router, this specific case would result in the same effective path as without the core
+// segment, with both the ingress _and_ the egress router performing a segment cross over
+// (https://github.com/scionproto/scion/issues/4524).
+func MalformedPathSingletonSegment(artifactsDir string, mac hash.Hash) runner.Case {
+	options := gopacket.SerializeOptions{
+		FixLengths:       true,
+		ComputeChecksums: true,
+	}
+
+	ethernet := &layers.Ethernet{
+		SrcMAC:       net.HardwareAddr{0xf0, 0x0d, 0xca, 0xfe, 0xbe, 0xef},
+		DstMAC:       net.HardwareAddr{0xf0, 0x0d, 0xca, 0xfe, 0x00, 0x15},
+		EthernetType: layers.EthernetTypeIPv4,
+	}
+
+	ip := &layers.IPv4{
+		Version:  4,
+		IHL:      5,
+		TTL:      64,
+		SrcIP:    net.IP{192, 168, 15, 3},
+		DstIP:    net.IP{192, 168, 15, 2},
+		Protocol: layers.IPProtocolUDP,
+		Flags:    layers.IPv4DontFragment,
+	}
+
+	udp := &layers.UDP{
+		SrcPort: layers.UDPPort(40000),
+		DstPort: layers.UDPPort(50000),
+	}
+	_ = udp.SetNetworkLayerForChecksum(ip)
+
+	sp := &scion.Decoded{
+		Base: scion.Base{
+			PathMeta: scion.MetaHdr{
+				CurrHF:  1,
+				CurrINF: 0,
+				SegLen:  [3]uint8{2, 1, 2},
+			},
+			NumINF:  3,
+			NumHops: 5,
+		},
+		InfoFields: []path.InfoField{
+			// up seg
+			{
+				SegID:     0x111,
+				ConsDir:   false,
+				Timestamp: util.TimeToSecs(time.Now()),
+			},
+			// core seg
+			{
+				SegID:     0x333,
+				ConsDir:   false,
+				Timestamp: util.TimeToSecs(time.Now()),
+			},
+			// down seg
+			{
+				SegID:     0x222,
+				ConsDir:   true,
+				Timestamp: util.TimeToSecs(time.Now()),
+			},
+		},
+		HopFields: []path.HopField{
+			{ConsIngress: 511, ConsEgress: 0},
+			{ConsIngress: 0, ConsEgress: 151}, // \
+			{ConsIngress: 141, ConsEgress: 0}, // | ff00:0:1
+			{ConsIngress: 0, ConsEgress: 141}, // /
+			{ConsIngress: 411, ConsEgress: 0},
+		},
+	}
+	sp.HopFields[1].Mac = path.MAC(mac, sp.InfoFields[0], sp.HopFields[1], nil)
+	sp.InfoFields[0].UpdateSegID(sp.HopFields[1].Mac)
+	sp.HopFields[2].Mac = path.MAC(mac, sp.InfoFields[1], sp.HopFields[2], nil)
+	sp.HopFields[3].Mac = path.MAC(mac, sp.InfoFields[2], sp.HopFields[3], nil)
+
+	scionL := &slayers.SCION{
+		Version:      0,
+		TrafficClass: 0xb8,
+		FlowID:       0xdead,
+		NextHdr:      slayers.L4UDP,
+		PathType:     scion.PathType,
+		SrcIA:        addr.MustParseIA("1-ff00:0:5"),
+		DstIA:        addr.MustParseIA("1-ff00:0:4"),
+		Path:         sp,
+	}
+
+	if err := scionL.SetSrcAddr(addr.MustParseHost("172.16.5.1")); err != nil {
+		panic(err)
+	}
+	if err := scionL.SetDstAddr(addr.MustParseHost("174.16.4.1")); err != nil {
+		panic(err)
+	}
+
+	scionudp := &slayers.UDP{}
+	scionudp.SrcPort = 40111
+	scionudp.DstPort = 40222
+	scionudp.SetNetworkLayerForChecksum(scionL)
+
+	payload := []byte("actualpayloadbytes")
+
+	// Prepare input packet
+	input := gopacket.NewSerializeBuffer()
+	if err := gopacket.SerializeLayers(input, options,
+		ethernet, ip, udp, scionL, scionudp, gopacket.Payload(payload),
+	); err != nil {
+		panic(err)
+	}
+
+	return runner.Case{
+		Name:     "MalformedPathSingletonSegment",
+		WriteTo:  "veth_151_host",
+		ReadFrom: "no_pkt_expected",
+		Input:    input.Bytes(),
+		Want:     nil,
+		StoreDir: filepath.Join(artifactsDir, "MalformedPathSingletonSegment"),
+	}
+}
+
+// MalformedPathCurrHFNotInCurrINF tests an invalid combination of CurrHF and CurrINF
+func MalformedPathCurrHFNotInCurrINF(artifactsDir string, mac hash.Hash) runner.Case {
+	options := gopacket.SerializeOptions{
+		FixLengths:       true,
+		ComputeChecksums: true,
+	}
+
+	ethernet := &layers.Ethernet{
+		SrcMAC:       net.HardwareAddr{0xf0, 0x0d, 0xca, 0xfe, 0xbe, 0xef},
+		DstMAC:       net.HardwareAddr{0xf0, 0x0d, 0xca, 0xfe, 0x00, 0x13},
+		EthernetType: layers.EthernetTypeIPv4,
+	}
+	ip := &layers.IPv4{
+		Version:  4,
+		IHL:      5,
+		TTL:      64,
+		SrcIP:    net.IP{192, 168, 13, 3},
+		DstIP:    net.IP{192, 168, 13, 2},
+		Protocol: layers.IPProtocolUDP,
+		Flags:    layers.IPv4DontFragment,
+	}
+	udp := &layers.UDP{
+		SrcPort: layers.UDPPort(40000),
+		DstPort: layers.UDPPort(50000),
+	}
+	_ = udp.SetNetworkLayerForChecksum(ip)
+
+	sp := &scion.Decoded{
+		Base: scion.Base{
+			PathMeta: scion.MetaHdr{
+				CurrINF: 0, // BAD! CurrHF points into second segment (CurrINF=1)
+				CurrHF:  3,
+				SegLen:  [3]uint8{2, 3, 0},
+			},
+			NumINF:  2,
+			NumHops: 5,
+		},
+		InfoFields: []path.InfoField{
+			// core segment
+			{
+				SegID:     0x222,
+				ConsDir:   true,
+				Timestamp: util.TimeToSecs(time.Now()),
+			},
+			// down segment
+			{
+				SegID:     0x111,
+				ConsDir:   true,
+				Timestamp: util.TimeToSecs(time.Now()),
+			},
+		},
+		HopFields: []path.HopField{
+			{ConsIngress: 0, ConsEgress: 1337},
+			{ConsIngress: 4242, ConsEgress: 0},
+			{ConsIngress: 0, ConsEgress: 311},
+			{ConsIngress: 131, ConsEgress: 151},
+			{ConsIngress: 511, ConsEgress: 0},
+		},
+	}
+
+	// Set up impossible/wrong MAC for current HF, so the MAC is valid for in the _wrong_ segment.
+	// This ensures that the check for the valid CurrHF / CurrINF applies independent of the MAC
+	// validation.
+	sp.HopFields[3].Mac = path.MAC(mac, sp.InfoFields[0], sp.HopFields[3], nil)
+
+	scionL := &slayers.SCION{
+		Version:      0,
+		TrafficClass: 0xb8,
+		FlowID:       0xdead,
+		NextHdr:      slayers.L4UDP,
+		PathType:     scion.PathType,
+		SrcIA:        addr.MustParseIA("2-ff00:0:42"),
+		DstIA:        addr.MustParseIA("1-ff00:0:5"),
+		Path:         sp,
+	}
+	if err := scionL.SetSrcAddr(addr.MustParseHost("172.16.3.1")); err != nil {
+		panic(err)
+	}
+	if err := scionL.SetDstAddr(addr.MustParseHost("172.16.5.1")); err != nil {
+		panic(err)
+	}
+
+	scionudp := &slayers.UDP{}
+	scionudp.SrcPort = 2354
+	scionudp.DstPort = 21000
+	scionudp.SetNetworkLayerForChecksum(scionL)
+
+	payload := []byte("actualpayloadbytes")
+
+	// Prepare input packet
+	input := gopacket.NewSerializeBuffer()
+	if err := gopacket.SerializeLayers(input, options,
+		ethernet, ip, udp, scionL, scionudp, gopacket.Payload(payload),
+	); err != nil {
+		panic(err)
+	}
+
+	return runner.Case{
+		Name:     "MalformedPathCurrHFNotInCurrINF",
+		WriteTo:  "veth_131_host",
+		ReadFrom: "no_pkt_expected",
+		Input:    input.Bytes(),
+		Want:     nil,
+		StoreDir: filepath.Join(artifactsDir, "MalformedPathCurrHFNotInCurrINF"),
+	}
+}
diff --git a/tools/braccept/main.go b/tools/braccept/main.go
@@ -124,6 +124,8 @@ func realMain() int {
 		cases.SCMPInvalidSrcIAChildToParent(artifactsDir, hfMAC),
 		cases.SCMPInvalidDstIAChildToParent(artifactsDir, hfMAC),
 		cases.NoSCMPReplyForSCMPError(artifactsDir, hfMAC),
+		cases.MalformedPathSingletonSegment(artifactsDir, hfMAC),
+		cases.MalformedPathCurrHFNotInCurrINF(artifactsDir, hfMAC),
 		cases.IncomingOneHop(artifactsDir, hfMAC),
 		cases.OutgoingOneHop(artifactsDir, hfMAC),
 		cases.SVC(artifactsDir, hfMAC),