Add support for IP_RECVORIGDSTADDR IP option.

Fixes #5004

PiperOrigin-RevId: 346643745

10 files changed, 206 insertions, 18 deletions

diff --git a/pkg/sentry/socket/control/control.go b/pkg/sentry/socket/control/control.go
index 70ccf77a7..c284efde5 100644
--- a/pkg/sentry/socket/control/control.go
+++ b/pkg/sentry/socket/control/control.go
@@ -359,13 +359,26 @@ func PackIPPacketInfo(t *kernel.Task, packetInfo tcpip.IPPacketInfo, buf []byte)
 	)
 }
 
+// PackOriginalDstAddress packs an IP_RECVORIGINALDSTADDR socket control message.
+func PackOriginalDstAddress(t *kernel.Task, family int, originalDstAddress tcpip.FullAddress, buf []byte) []byte {
+	p, _ := socket.ConvertAddress(family, originalDstAddress)
+	level := uint32(linux.SOL_IP)
+	optType := uint32(linux.IP_RECVORIGDSTADDR)
+	if family == linux.AF_INET6 {
+		level = linux.SOL_IPV6
+		optType = linux.IPV6_RECVORIGDSTADDR
+	}
+	return putCmsgStruct(
+		buf, level, optType, t.Arch().Width(), p)
+}
+
 // PackControlMessages packs control messages into the given buffer.
 //
 // We skip control messages specific to Unix domain sockets.
 //
 // Note that some control messages may be truncated if they do not fit under
 // the capacity of buf.
-func PackControlMessages(t *kernel.Task, cmsgs socket.ControlMessages, buf []byte) []byte {
+func PackControlMessages(t *kernel.Task, family int, cmsgs socket.ControlMessages, buf []byte) []byte {
 	if cmsgs.IP.HasTimestamp {
 		buf = PackTimestamp(t, cmsgs.IP.Timestamp, buf)
 	}
@@ -387,6 +400,10 @@ func PackControlMessages(t *kernel.Task, cmsgs socket.ControlMessages, buf []byt
 		buf = PackIPPacketInfo(t, cmsgs.IP.PacketInfo, buf)
 	}
 
+	if cmsgs.IP.HasOriginalDstAddress {
+		buf = PackOriginalDstAddress(t, family, cmsgs.IP.OriginalDstAddress, buf)
+	}
+
 	return buf
 }
 
diff --git a/pkg/sentry/socket/hostinet/socket.go b/pkg/sentry/socket/hostinet/socket.go
index 7d3c4a01c..a35850a8f 100644
--- a/pkg/sentry/socket/hostinet/socket.go
+++ b/pkg/sentry/socket/hostinet/socket.go
@@ -551,7 +551,7 @@ func (s *socketOpsCommon) SendMsg(t *kernel.Task, src usermem.IOSequence, to []b
 	}
 	controlBuf := make([]byte, 0, space)
 	// PackControlMessages will append up to space bytes to controlBuf.
-	controlBuf = control.PackControlMessages(t, controlMessages, controlBuf)
+	controlBuf = control.PackControlMessages(t, s.family, controlMessages, controlBuf)
 
 	sendmsgFromBlocks := safemem.WriterFunc(func(srcs safemem.BlockSeq) (uint64, error) {
 		// Refuse to do anything if any part of src.Addrs was unusable.
diff --git a/pkg/sentry/socket/netstack/netstack.go b/pkg/sentry/socket/netstack/netstack.go
index 3cc0d4f0f..37c3faa57 100644
--- a/pkg/sentry/socket/netstack/netstack.go
+++ b/pkg/sentry/socket/netstack/netstack.go
@@ -1418,6 +1418,14 @@ func getSockOptIPv6(t *kernel.Task, s socket.SocketOps, ep commonEndpoint, name
 		v := primitive.Int32(boolToInt32(ep.SocketOptions().GetReceiveTClass()))
 		return &v, nil
 
+	case linux.IPV6_RECVORIGDSTADDR:
+		if outLen < sizeOfInt32 {
+			return nil, syserr.ErrInvalidArgument
+		}
+
+		v := primitive.Int32(boolToInt32(ep.SocketOptions().GetReceiveOriginalDstAddress()))
+		return &v, nil
+
 	case linux.IP6T_ORIGINAL_DST:
 		if outLen < int(binary.Size(linux.SockAddrInet6{})) {
 			return nil, syserr.ErrInvalidArgument
@@ -1599,6 +1607,14 @@ func getSockOptIP(t *kernel.Task, s socket.SocketOps, ep commonEndpoint, name in
 		v := primitive.Int32(boolToInt32(ep.SocketOptions().GetHeaderIncluded()))
 		return &v, nil
 
+	case linux.IP_RECVORIGDSTADDR:
+		if outLen < sizeOfInt32 {
+			return nil, syserr.ErrInvalidArgument
+		}
+
+		v := primitive.Int32(boolToInt32(ep.SocketOptions().GetReceiveOriginalDstAddress()))
+		return &v, nil
+
 	case linux.SO_ORIGINAL_DST:
 		if outLen < int(binary.Size(linux.SockAddrInet{})) {
 			return nil, syserr.ErrInvalidArgument
@@ -2094,6 +2110,15 @@ func setSockOptIPv6(t *kernel.Task, s socket.SocketOps, ep commonEndpoint, name
 
 		t.Kernel().EmitUnimplementedEvent(t)
 
+	case linux.IPV6_RECVORIGDSTADDR:
+		if len(optVal) < sizeOfInt32 {
+			return syserr.ErrInvalidArgument
+		}
+		v := int32(usermem.ByteOrder.Uint32(optVal))
+
+		ep.SocketOptions().SetReceiveOriginalDstAddress(v != 0)
+		return nil
+
 	case linux.IPV6_TCLASS:
 		if len(optVal) < sizeOfInt32 {
 			return syserr.ErrInvalidArgument
@@ -2325,6 +2350,18 @@ func setSockOptIP(t *kernel.Task, s socket.SocketOps, ep commonEndpoint, name in
 		ep.SocketOptions().SetHeaderIncluded(v != 0)
 		return nil
 
+	case linux.IP_RECVORIGDSTADDR:
+		if len(optVal) == 0 {
+			return nil
+		}
+		v, err := parseIntOrChar(optVal)
+		if err != nil {
+			return err
+		}
+
+		ep.SocketOptions().SetReceiveOriginalDstAddress(v != 0)
+		return nil
+
 	case linux.IPT_SO_SET_REPLACE:
 		if len(optVal) < linux.SizeOfIPTReplace {
 			return syserr.ErrInvalidArgument
@@ -2363,7 +2400,6 @@ func setSockOptIP(t *kernel.Task, s socket.SocketOps, ep commonEndpoint, name in
 		linux.IP_RECVERR,
 		linux.IP_RECVFRAGSIZE,
 		linux.IP_RECVOPTS,
-		linux.IP_RECVORIGDSTADDR,
 		linux.IP_RECVTTL,
 		linux.IP_RETOPTS,
 		linux.IP_TRANSPARENT,
@@ -2441,7 +2477,6 @@ func emitUnimplementedEventIPv6(t *kernel.Task, name int) {
 		linux.IPV6_RECVFRAGSIZE,
 		linux.IPV6_RECVHOPLIMIT,
 		linux.IPV6_RECVHOPOPTS,
-		linux.IPV6_RECVORIGDSTADDR,
 		linux.IPV6_RECVPATHMTU,
 		linux.IPV6_RECVPKTINFO,
 		linux.IPV6_RECVRTHDR,
@@ -2746,14 +2781,16 @@ func (s *socketOpsCommon) nonBlockingRead(ctx context.Context, dst usermem.IOSeq
 func (s *socketOpsCommon) controlMessages() socket.ControlMessages {
 	return socket.ControlMessages{
 		IP: tcpip.ControlMessages{
-			HasTimestamp:    s.readCM.HasTimestamp && s.sockOptTimestamp,
-			Timestamp:       s.readCM.Timestamp,
-			HasTOS:          s.readCM.HasTOS,
-			TOS:             s.readCM.TOS,
-			HasTClass:       s.readCM.HasTClass,
-			TClass:          s.readCM.TClass,
-			HasIPPacketInfo: s.readCM.HasIPPacketInfo,
-			PacketInfo:      s.readCM.PacketInfo,
+			HasTimestamp:          s.readCM.HasTimestamp && s.sockOptTimestamp,
+			Timestamp:             s.readCM.Timestamp,
+			HasTOS:                s.readCM.HasTOS,
+			TOS:                   s.readCM.TOS,
+			HasTClass:             s.readCM.HasTClass,
+			TClass:                s.readCM.TClass,
+			HasIPPacketInfo:       s.readCM.HasIPPacketInfo,
+			PacketInfo:            s.readCM.PacketInfo,
+			HasOriginalDstAddress: s.readCM.HasOriginalDstAddress,
+			OriginalDstAddress:    s.readCM.OriginalDstAddress,
 		},
 	}
 }
diff --git a/pkg/sentry/syscalls/linux/sys_socket.go b/pkg/sentry/syscalls/linux/sys_socket.go
index 9cd052c3d..754a5df24 100644
--- a/pkg/sentry/syscalls/linux/sys_socket.go
+++ b/pkg/sentry/syscalls/linux/sys_socket.go
@@ -784,8 +784,9 @@ func recvSingleMsg(t *kernel.Task, s socket.Socket, msgPtr usermem.Addr, flags i
 	}
 	defer cms.Release(t)
 
+	family, _, _ := s.Type()
 	controlData := make([]byte, 0, msg.ControlLen)
-	controlData = control.PackControlMessages(t, cms, controlData)
+	controlData = control.PackControlMessages(t, family, cms, controlData)
 
 	if cr, ok := s.(transport.Credentialer); ok && cr.Passcred() {
 		creds, _ := cms.Unix.Credentials.(control.SCMCredentials)
diff --git a/pkg/sentry/syscalls/linux/vfs2/socket.go b/pkg/sentry/syscalls/linux/vfs2/socket.go
index 7b33b3f59..c40892b9f 100644
--- a/pkg/sentry/syscalls/linux/vfs2/socket.go
+++ b/pkg/sentry/syscalls/linux/vfs2/socket.go
@@ -787,8 +787,9 @@ func recvSingleMsg(t *kernel.Task, s socket.SocketVFS2, msgPtr usermem.Addr, fla
 	}
 	defer cms.Release(t)
 
+	family, _, _ := s.Type()
 	controlData := make([]byte, 0, msg.ControlLen)
-	controlData = control.PackControlMessages(t, cms, controlData)
+	controlData = control.PackControlMessages(t, family, cms, controlData)
 
 	if cr, ok := s.(transport.Credentialer); ok && cr.Passcred() {
 		creds, _ := cms.Unix.Credentials.(control.SCMCredentials)
diff --git a/pkg/tcpip/checker/checker.go b/pkg/tcpip/checker/checker.go
index d3ae56ac6..8830c45d7 100644
--- a/pkg/tcpip/checker/checker.go
+++ b/pkg/tcpip/checker/checker.go
@@ -321,6 +321,19 @@ func ReceiveIPPacketInfo(want tcpip.IPPacketInfo) ControlMessagesChecker {
 	}
 }
 
+// ReceiveOriginalDstAddr creates a checker that checks the OriginalDstAddress
+// field in ControlMessages.
+func ReceiveOriginalDstAddr(want tcpip.FullAddress) ControlMessagesChecker {
+	return func(t *testing.T, cm tcpip.ControlMessages) {
+		t.Helper()
+		if !cm.HasOriginalDstAddress {
+			t.Errorf("got cm.HasOriginalDstAddress = %t, want = true", cm.HasOriginalDstAddress)
+		} else if diff := cmp.Diff(want, cm.OriginalDstAddress); diff != "" {
+			t.Errorf("OriginalDstAddress mismatch (-want +got):\n%s", diff)
+		}
+	}
+}
+
 // TOS creates a checker that checks the TOS field.
 func TOS(tos uint8, label uint32) NetworkChecker {
 	return func(t *testing.T, h []header.Network) {
diff --git a/pkg/tcpip/socketops.go b/pkg/tcpip/socketops.go
index c53698a6a..b14df9e09 100644
--- a/pkg/tcpip/socketops.go
+++ b/pkg/tcpip/socketops.go
@@ -130,6 +130,10 @@ type SocketOptions struct {
 	// corkOptionEnabled is used to specify if data should be held until segments
 	// are full by the TCP transport protocol.
 	corkOptionEnabled uint32
+
+	// receiveOriginalDstAddress is used to specify if the original destination of
+	// the incoming packet should be returned as an ancillary message.
+	receiveOriginalDstAddress uint32
 }
 
 // InitHandler initializes the handler. This must be called before using the
@@ -302,3 +306,13 @@ func (so *SocketOptions) SetCorkOption(v bool) {
 	storeAtomicBool(&so.corkOptionEnabled, v)
 	so.handler.OnCorkOptionSet(v)
 }
+
+// GetReceiveOriginalDstAddress gets value for IP(V6)_RECVORIGDSTADDR option.
+func (so *SocketOptions) GetReceiveOriginalDstAddress() bool {
+	return atomic.LoadUint32(&so.receiveOriginalDstAddress) != 0
+}
+
+// SetReceiveOriginalDstAddress sets value for IP(V6)_RECVORIGDSTADDR option.
+func (so *SocketOptions) SetReceiveOriginalDstAddress(v bool) {
+	storeAtomicBool(&so.receiveOriginalDstAddress, v)
+}
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index 23e597365..0d2dad881 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -492,6 +492,14 @@ type ControlMessages struct {
 
 	// PacketInfo holds interface and address data on an incoming packet.
 	PacketInfo IPPacketInfo
+
+	// HasOriginalDestinationAddress indicates whether OriginalDstAddress is
+	// set.
+	HasOriginalDstAddress bool
+
+	// OriginalDestinationAddress holds the original destination address
+	// and port of the incoming packet.
+	OriginalDstAddress FullAddress
 }
 
 // PacketOwner is used to get UID and GID of the packet.
diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index ee1bb29f8..04596183e 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -30,10 +30,11 @@ import (
 // +stateify savable
 type udpPacket struct {
 	udpPacketEntry
-	senderAddress tcpip.FullAddress
-	packetInfo    tcpip.IPPacketInfo
-	data          buffer.VectorisedView `state:".(buffer.VectorisedView)"`
-	timestamp     int64
+	senderAddress      tcpip.FullAddress
+	destinationAddress tcpip.FullAddress
+	packetInfo         tcpip.IPPacketInfo
+	data               buffer.VectorisedView `state:".(buffer.VectorisedView)"`
+	timestamp          int64
 	// tos stores either the receiveTOS or receiveTClass value.
 	tos uint8
 }
@@ -323,6 +324,10 @@ func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMess
 		cm.HasIPPacketInfo = true
 		cm.PacketInfo = p.packetInfo
 	}
+	if e.ops.GetReceiveOriginalDstAddress() {
+		cm.HasOriginalDstAddress = true
+		cm.OriginalDstAddress = p.destinationAddress
+	}
 	return p.data.ToView(), cm, nil
 }
 
@@ -1314,6 +1319,11 @@ func (e *endpoint) HandlePacket(id stack.TransportEndpointID, pkt *stack.PacketB
 			Addr: id.RemoteAddress,
 			Port: hdr.SourcePort(),
 		},
+		destinationAddress: tcpip.FullAddress{
+			NIC:  pkt.NICID,
+			Addr: id.LocalAddress,
+			Port: header.UDP(hdr).DestinationPort(),
+		},
 	}
 	packet.data = pkt.Data
 	e.rcvList.PushBack(packet)
diff --git a/pkg/tcpip/transport/udp/udp_test.go b/pkg/tcpip/transport/udp/udp_test.go
index b0b9b2773..cca865b34 100644
--- a/pkg/tcpip/transport/udp/udp_test.go
+++ b/pkg/tcpip/transport/udp/udp_test.go
@@ -1428,6 +1428,93 @@ func TestReadIPPacketInfo(t *testing.T) {
 	}
 }
 
+func TestReadRecvOriginalDstAddr(t *testing.T) {
+	tests := []struct {
+		name                    string
+		proto                   tcpip.NetworkProtocolNumber
+		flow                    testFlow
+		expectedOriginalDstAddr tcpip.FullAddress
+	}{
+		{
+			name:                    "IPv4 unicast",
+			proto:                   header.IPv4ProtocolNumber,
+			flow:                    unicastV4,
+			expectedOriginalDstAddr: tcpip.FullAddress{1, stackAddr, stackPort},
+		},
+		{
+			name:  "IPv4 multicast",
+			proto: header.IPv4ProtocolNumber,
+			flow:  multicastV4,
+			// This should actually be a unicast address assigned to the interface.
+			//
+			// TODO(gvisor.dev/issue/3556): This check is validating incorrect
+			// behaviour. We still include the test so that once the bug is
+			// resolved, this test will start to fail and the individual tasked
+			// with fixing this bug knows to also fix this test :).
+			expectedOriginalDstAddr: tcpip.FullAddress{1, multicastAddr, stackPort},
+		},
+		{
+			name:  "IPv4 broadcast",
+			proto: header.IPv4ProtocolNumber,
+			flow:  broadcast,
+			// This should actually be a unicast address assigned to the interface.
+			//
+			// TODO(gvisor.dev/issue/3556): This check is validating incorrect
+			// behaviour. We still include the test so that once the bug is
+			// resolved, this test will start to fail and the individual tasked
+			// with fixing this bug knows to also fix this test :).
+			expectedOriginalDstAddr: tcpip.FullAddress{1, broadcastAddr, stackPort},
+		},
+		{
+			name:                    "IPv6 unicast",
+			proto:                   header.IPv6ProtocolNumber,
+			flow:                    unicastV6,
+			expectedOriginalDstAddr: tcpip.FullAddress{1, stackV6Addr, stackPort},
+		},
+		{
+			name:  "IPv6 multicast",
+			proto: header.IPv6ProtocolNumber,
+			flow:  multicastV6,
+			// This should actually be a unicast address assigned to the interface.
+			//
+			// TODO(gvisor.dev/issue/3556): This check is validating incorrect
+			// behaviour. We still include the test so that once the bug is
+			// resolved, this test will start to fail and the individual tasked
+			// with fixing this bug knows to also fix this test :).
+			expectedOriginalDstAddr: tcpip.FullAddress{1, multicastV6Addr, stackPort},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			c := newDualTestContext(t, defaultMTU)
+			defer c.cleanup()
+
+			c.createEndpoint(test.proto)
+
+			bindAddr := tcpip.FullAddress{Port: stackPort}
+			if err := c.ep.Bind(bindAddr); err != nil {
+				t.Fatalf("Bind(%+v): %s", bindAddr, err)
+			}
+
+			if test.flow.isMulticast() {
+				ifoptSet := tcpip.AddMembershipOption{NIC: 1, MulticastAddr: test.flow.getMcastAddr()}
+				if err := c.ep.SetSockOpt(&ifoptSet); err != nil {
+					c.t.Fatalf("SetSockOpt(&%#v): %s:", ifoptSet, err)
+				}
+			}
+
+			c.ep.SocketOptions().SetReceiveOriginalDstAddress(true)
+
+			testRead(c, test.flow, checker.ReceiveOriginalDstAddr(test.expectedOriginalDstAddr))
+
+			if got := c.s.Stats().UDP.PacketsReceived.Value(); got != 1 {
+				t.Fatalf("Read did not increment PacketsReceived: got = %d, want = 1", got)
+			}
+		})
+	}
+}
+
 func TestWriteIncrementsPacketsSent(t *testing.T) {
 	c := newDualTestContext(t, defaultMTU)
 	defer c.cleanup()