From e07fd058ec474d801748a849d9c5d1c6118c3c11 Mon Sep 17 00:00:00 2001
From: Ghanan Gowripalan <ghanan@google.com>
Date: Mon, 13 Sep 2021 14:40:18 -0700
Subject: Set NICID before delivering packet to raw endpoint

...as raw endpoints expect the packet's NICID to be set.

PiperOrigin-RevId: 396446552
---
 pkg/tcpip/network/BUILD        |  2 +
 pkg/tcpip/network/ip_test.go   | 93 ++++++++++++++++++++++++++++++++++++++++++
 pkg/tcpip/network/ipv4/ipv4.go |  3 +-
 pkg/tcpip/network/ipv6/ipv6.go |  3 +-
 4 files changed, 99 insertions(+), 2 deletions(-)

diff --git a/pkg/tcpip/network/BUILD b/pkg/tcpip/network/BUILD
index 7b1ff44f4..c0179104a 100644
--- a/pkg/tcpip/network/BUILD
+++ b/pkg/tcpip/network/BUILD
@@ -23,8 +23,10 @@ go_test(
         "//pkg/tcpip/stack",
         "//pkg/tcpip/testutil",
         "//pkg/tcpip/transport/icmp",
+        "//pkg/tcpip/transport/raw",
         "//pkg/tcpip/transport/tcp",
         "//pkg/tcpip/transport/udp",
+        "//pkg/waiter",
         "@com_github_google_go_cmp//cmp:go_default_library",
     ],
 )
diff --git a/pkg/tcpip/network/ip_test.go b/pkg/tcpip/network/ip_test.go
index 771b9173a..2179302d3 100644
--- a/pkg/tcpip/network/ip_test.go
+++ b/pkg/tcpip/network/ip_test.go
@@ -15,6 +15,7 @@
 package ip_test
 
 import (
+	"bytes"
 	"fmt"
 	"strings"
 	"testing"
@@ -32,8 +33,10 @@ import (
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 	"gvisor.dev/gvisor/pkg/tcpip/testutil"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/raw"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
+	"gvisor.dev/gvisor/pkg/waiter"
 )
 
 const nicID = 1
@@ -2032,3 +2035,93 @@ func TestJoinLeaveAllRoutersGroup(t *testing.T) {
 		})
 	}
 }
+
+func TestSetNICIDBeforeDeliveringToRawEndpoint(t *testing.T) {
+	const nicID = 1
+
+	tests := []struct {
+		name          string
+		proto         tcpip.NetworkProtocolNumber
+		addr          tcpip.AddressWithPrefix
+		payloadOffset int
+	}{
+		{
+			name:          "IPv4",
+			proto:         header.IPv4ProtocolNumber,
+			addr:          localIPv4AddrWithPrefix,
+			payloadOffset: header.IPv4MinimumSize,
+		},
+		{
+			name:          "IPv6",
+			proto:         header.IPv6ProtocolNumber,
+			addr:          localIPv6AddrWithPrefix,
+			payloadOffset: 0,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			s := stack.New(stack.Options{
+				NetworkProtocols: []stack.NetworkProtocolFactory{
+					ipv4.NewProtocol,
+					ipv6.NewProtocol,
+				},
+				TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol},
+				RawFactory:         raw.EndpointFactory{},
+			})
+			if err := s.CreateNIC(nicID, loopback.New()); err != nil {
+				t.Fatalf("CreateNIC(%d, _): %s", nicID, err)
+			}
+			if err := s.AddAddressWithPrefix(nicID, test.proto, test.addr); err != nil {
+				t.Fatalf("AddAddressWithPrefix(%d, %d, %s): %s", nicID, test.proto, test.addr, err)
+			}
+
+			s.SetRouteTable([]tcpip.Route{
+				{
+					Destination: test.addr.Subnet(),
+					NIC:         nicID,
+				},
+			})
+
+			var wq waiter.Queue
+			we, ch := waiter.NewChannelEntry(nil)
+			wq.EventRegister(&we, waiter.ReadableEvents)
+			ep, err := s.NewRawEndpoint(udp.ProtocolNumber, test.proto, &wq, true /* associated */)
+			if err != nil {
+				t.Fatalf("NewEndpoint(%d, %d, _): %s", udp.ProtocolNumber, test.proto, err)
+			}
+			defer ep.Close()
+
+			writeOpts := tcpip.WriteOptions{
+				To: &tcpip.FullAddress{
+					Addr: test.addr.Address,
+				},
+			}
+			data := []byte{1, 2, 3, 4}
+			var r bytes.Reader
+			r.Reset(data)
+			if n, err := ep.Write(&r, writeOpts); err != nil {
+				t.Fatalf("ep.Write(_, _): %s", err)
+			} else if want := int64(len(data)); n != want {
+				t.Fatalf("got ep.Write(_, _) = (%d, nil), want = (%d, nil)", n, want)
+			}
+
+			// Wait for the endpoint to become readable.
+			<-ch
+
+			var w bytes.Buffer
+			rr, err := ep.Read(&w, tcpip.ReadOptions{
+				NeedRemoteAddr: true,
+			})
+			if err != nil {
+				t.Fatalf("ep.Read(...): %s", err)
+			}
+			if diff := cmp.Diff(data, w.Bytes()[test.payloadOffset:]); diff != "" {
+				t.Errorf("payload mismatch (-want +got):\n%s", diff)
+			}
+			if diff := cmp.Diff(tcpip.FullAddress{Addr: test.addr.Address, NIC: nicID}, rr.RemoteAddr); diff != "" {
+				t.Errorf("remote addr mismatch (-want +got):\n%s", diff)
+			}
+		})
+	}
+}
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index 44c85bdb8..e2472c851 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -856,6 +856,8 @@ func (e *endpoint) handleLocalPacket(pkt *stack.PacketBuffer, canSkipRXChecksum
 }
 
 func (e *endpoint) handleValidatedPacket(h header.IPv4, pkt *stack.PacketBuffer, inNICName string) {
+	pkt.NICID = e.nic.ID()
+
 	// Raw socket packets are delivered based solely on the transport protocol
 	// number. We only require that the packet be valid IPv4, and that they not
 	// be fragmented.
@@ -863,7 +865,6 @@ func (e *endpoint) handleValidatedPacket(h header.IPv4, pkt *stack.PacketBuffer,
 		e.dispatcher.DeliverRawPacket(h.TransportProtocol(), pkt)
 	}
 
-	pkt.NICID = e.nic.ID()
 	stats := e.stats
 	stats.ip.ValidPacketsReceived.Increment()
 
diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go
index b1aec5312..d4bd61748 100644
--- a/pkg/tcpip/network/ipv6/ipv6.go
+++ b/pkg/tcpip/network/ipv6/ipv6.go
@@ -1127,11 +1127,12 @@ func (e *endpoint) handleLocalPacket(pkt *stack.PacketBuffer, canSkipRXChecksum
 }
 
 func (e *endpoint) handleValidatedPacket(h header.IPv6, pkt *stack.PacketBuffer, inNICName string) {
+	pkt.NICID = e.nic.ID()
+
 	// Raw socket packets are delivered based solely on the transport protocol
 	// number. We only require that the packet be valid IPv6.
 	e.dispatcher.DeliverRawPacket(h.TransportProtocol(), pkt)
 
-	pkt.NICID = e.nic.ID()
 	stats := e.stats.ip
 	stats.ValidPacketsReceived.Increment()
 
-- 
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