1 files changed, 558 insertions, 0 deletions
diff --git a/pkg/tcpip/transport/raw/endpoint.go b/pkg/tcpip/transport/raw/endpoint.go
new file mode 100644
index 000000000..7004c7ff4
--- /dev/null
+++ b/pkg/tcpip/transport/raw/endpoint.go
@@ -0,0 +1,558 @@
+// Copyright 2019 The gVisor Authors.
+//
+// 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 raw provides the implementation of raw sockets (see raw(7)). Raw
+// sockets allow applications to:
+//
+//   * manually write and inspect transport layer headers and payloads
+//   * receive all traffic of a given transport protcol (e.g. ICMP or UDP)
+//   * optionally write and inspect network layer and link layer headers for
+//     packets
+//
+// Raw sockets don't have any notion of ports, and incoming packets are
+// demultiplexed solely by protocol number. Thus, a raw UDP endpoint will
+// receive every UDP packet received by netstack. bind(2) and connect(2) can be
+// used to filter incoming packets by source and destination.
+package raw
+
+import (
+	"sync"
+
+	"gvisor.googlesource.com/gvisor/pkg/sleep"
+	"gvisor.googlesource.com/gvisor/pkg/tcpip"
+	"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
+	"gvisor.googlesource.com/gvisor/pkg/tcpip/header"
+	"gvisor.googlesource.com/gvisor/pkg/tcpip/stack"
+	"gvisor.googlesource.com/gvisor/pkg/waiter"
+)
+
+// +stateify savable
+type packet struct {
+	packetEntry
+	// data holds the actual packet data, including any headers and
+	// payload.
+	data buffer.VectorisedView `state:".(buffer.VectorisedView)"`
+	// views is pre-allocated space to back data. As long as the packet is
+	// made up of fewer than 8 buffer.Views, no extra allocation is
+	// necessary to store packet data.
+	views [8]buffer.View `state:"nosave"`
+	// timestampNS is the unix time at which the packet was received.
+	timestampNS int64
+	// senderAddr is the network address of the sender.
+	senderAddr tcpip.FullAddress
+}
+
+// endpoint is the raw socket implementation of tcpip.Endpoint. It is legal to
+// have goroutines make concurrent calls into the endpoint.
+//
+// Lock order:
+//   endpoint.mu
+//     endpoint.rcvMu
+//
+// +stateify savable
+type endpoint struct {
+	// The following fields are initialized at creation time and are
+	// immutable.
+	stack       *stack.Stack `state:"manual"`
+	netProto    tcpip.NetworkProtocolNumber
+	transProto  tcpip.TransportProtocolNumber
+	waiterQueue *waiter.Queue
+
+	// The following fields are used to manage the receive queue and are
+	// protected by rcvMu.
+	rcvMu         sync.Mutex `state:"nosave"`
+	rcvList       packetList
+	rcvBufSizeMax int `state:".(int)"`
+	rcvBufSize    int
+	rcvClosed     bool
+
+	// The following fields are protected by mu.
+	mu         sync.RWMutex `state:"nosave"`
+	sndBufSize int
+	// shutdownFlags represent the current shutdown state of the endpoint.
+	shutdownFlags tcpip.ShutdownFlags
+	closed        bool
+	connected     bool
+	bound         bool
+	// registeredNIC is the NIC to which th endpoint is explicitly
+	// registered. Is set when Connect or Bind are used to specify a NIC.
+	registeredNIC tcpip.NICID
+	// boundNIC and boundAddr are set on calls to Bind(). When callers
+	// attempt actions that would invalidate the binding data (e.g. sending
+	// data via a NIC other than boundNIC), the endpoint will return an
+	// error.
+	boundNIC  tcpip.NICID
+	boundAddr tcpip.Address
+	// route is the route to a remote network endpoint. It is set via
+	// Connect(), and is valid only when conneted is true.
+	route stack.Route `state:"manual"`
+}
+
+// NewEndpoint returns a raw  endpoint for the given protocols.
+// TODO(b/129292371): IP_HDRINCL, IPPROTO_RAW, and AF_PACKET.
+func NewEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtocolNumber, transProto tcpip.TransportProtocolNumber, waiterQueue *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
+	if netProto != header.IPv4ProtocolNumber {
+		return nil, tcpip.ErrUnknownProtocol
+	}
+
+	ep := &endpoint{
+		stack:         stack,
+		netProto:      netProto,
+		transProto:    transProto,
+		waiterQueue:   waiterQueue,
+		rcvBufSizeMax: 32 * 1024,
+		sndBufSize:    32 * 1024,
+	}
+
+	if err := ep.stack.RegisterRawTransportEndpoint(ep.registeredNIC, ep.netProto, ep.transProto, ep); err != nil {
+		return nil, err
+	}
+
+	return ep, nil
+}
+
+// Close implements tcpip.Endpoint.Close.
+func (ep *endpoint) Close() {
+	ep.mu.Lock()
+	defer ep.mu.Unlock()
+
+	if ep.closed {
+		return
+	}
+
+	ep.stack.UnregisterRawTransportEndpoint(ep.registeredNIC, ep.netProto, ep.transProto, ep)
+
+	ep.rcvMu.Lock()
+	defer ep.rcvMu.Unlock()
+
+	// Clear the receive list.
+	ep.rcvClosed = true
+	ep.rcvBufSize = 0
+	for !ep.rcvList.Empty() {
+		ep.rcvList.Remove(ep.rcvList.Front())
+	}
+
+	if ep.connected {
+		ep.route.Release()
+	}
+
+	ep.waiterQueue.Notify(waiter.EventHUp | waiter.EventErr | waiter.EventIn | waiter.EventOut)
+}
+
+// Read implements tcpip.Endpoint.Read.
+func (ep *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMessages, *tcpip.Error) {
+	ep.rcvMu.Lock()
+
+	// If there's no data to read, return that read would block or that the
+	// endpoint is closed.
+	if ep.rcvList.Empty() {
+		err := tcpip.ErrWouldBlock
+		if ep.rcvClosed {
+			err = tcpip.ErrClosedForReceive
+		}
+		ep.rcvMu.Unlock()
+		return buffer.View{}, tcpip.ControlMessages{}, err
+	}
+
+	packet := ep.rcvList.Front()
+	ep.rcvList.Remove(packet)
+	ep.rcvBufSize -= packet.data.Size()
+
+	ep.rcvMu.Unlock()
+
+	if addr != nil {
+		*addr = packet.senderAddr
+	}
+
+	return packet.data.ToView(), tcpip.ControlMessages{HasTimestamp: true, Timestamp: packet.timestampNS}, nil
+}
+
+// Write implements tcpip.Endpoint.Write.
+func (ep *endpoint) Write(payload tcpip.Payload, opts tcpip.WriteOptions) (uintptr, <-chan struct{}, *tcpip.Error) {
+	// MSG_MORE is unimplemented. This also means that MSG_EOR is a no-op.
+	if opts.More {
+		return 0, nil, tcpip.ErrInvalidOptionValue
+	}
+
+	ep.mu.RLock()
+
+	if ep.closed {
+		ep.mu.RUnlock()
+		return 0, nil, tcpip.ErrInvalidEndpointState
+	}
+
+	// Check whether we've shutdown writing.
+	if ep.shutdownFlags&tcpip.ShutdownWrite != 0 {
+		ep.mu.RUnlock()
+		return 0, nil, tcpip.ErrClosedForSend
+	}
+
+	// Did the user caller provide a destination? If not, use the connected
+	// destination.
+	if opts.To == nil {
+		// If the user doesn't specify a destination, they should have
+		// connected to another address.
+		if !ep.connected {
+			ep.mu.RUnlock()
+			return 0, nil, tcpip.ErrNotConnected
+		}
+
+		if ep.route.IsResolutionRequired() {
+			savedRoute := &ep.route
+			// Promote lock to exclusive if using a shared route,
+			// given that it may need to change in finishWrite.
+			ep.mu.RUnlock()
+			ep.mu.Lock()
+
+			// Make sure that the route didn't change during the
+			// time we didn't hold the lock.
+			if !ep.connected || savedRoute != &ep.route {
+				ep.mu.Unlock()
+				return 0, nil, tcpip.ErrInvalidEndpointState
+			}
+
+			n, ch, err := ep.finishWrite(payload, savedRoute)
+			ep.mu.Unlock()
+			return n, ch, err
+		}
+
+		n, ch, err := ep.finishWrite(payload, &ep.route)
+		ep.mu.RUnlock()
+		return n, ch, err
+	}
+
+	// The caller provided a destination. Reject destination address if it
+	// goes through a different NIC than the endpoint was bound to.
+	nic := opts.To.NIC
+	if ep.bound && nic != 0 && nic != ep.boundNIC {
+		ep.mu.RUnlock()
+		return 0, nil, tcpip.ErrNoRoute
+	}
+
+	// We don't support IPv6 yet, so this has to be an IPv4 address.
+	if len(opts.To.Addr) != header.IPv4AddressSize {
+		ep.mu.RUnlock()
+		return 0, nil, tcpip.ErrInvalidEndpointState
+	}
+
+	// Find the route to the destination. If boundAddress is 0,
+	// FindRoute will choose an appropriate source address.
+	route, err := ep.stack.FindRoute(nic, ep.boundAddr, opts.To.Addr, ep.netProto, false)
+	if err != nil {
+		ep.mu.RUnlock()
+		return 0, nil, err
+	}
+
+	n, ch, err := ep.finishWrite(payload, &route)
+	route.Release()
+	ep.mu.RUnlock()
+	return n, ch, err
+}
+
+// finishWrite writes the payload to a route. It resolves the route if
+// necessary. It's really just a helper to make defer unnecessary in Write.
+func (ep *endpoint) finishWrite(payload tcpip.Payload, route *stack.Route) (uintptr, <-chan struct{}, *tcpip.Error) {
+	// We may need to resolve the route (match a link layer address to the
+	// network address). If that requires blocking (e.g. to use ARP),
+	// return a channel on which the caller can wait.
+	if route.IsResolutionRequired() {
+		waker := &sleep.Waker{}
+		if ch, err := route.Resolve(waker); err != nil {
+			if err == tcpip.ErrWouldBlock {
+				// Link address needs to be resolved.
+				// Resolution was triggered the background.
+				// Better luck next time.
+				route.RemoveWaker(waker)
+				return 0, ch, tcpip.ErrNoLinkAddress
+			}
+			return 0, nil, err
+		}
+	}
+
+	payloadBytes, err := payload.Get(payload.Size())
+	if err != nil {
+		return 0, nil, err
+	}
+
+	switch ep.netProto {
+	case header.IPv4ProtocolNumber:
+		hdr := buffer.NewPrependable(len(payloadBytes) + int(route.MaxHeaderLength()))
+		if err := route.WritePacket(nil /* gso */, hdr, buffer.View(payloadBytes).ToVectorisedView(), header.ICMPv4ProtocolNumber, route.DefaultTTL()); err != nil {
+			return 0, nil, err
+		}
+
+	default:
+		return 0, nil, tcpip.ErrUnknownProtocol
+	}
+
+	return uintptr(len(payloadBytes)), nil, nil
+}
+
+// Peek implements tcpip.Endpoint.Peek.
+func (ep *endpoint) Peek([][]byte) (uintptr, tcpip.ControlMessages, *tcpip.Error) {
+	return 0, tcpip.ControlMessages{}, nil
+}
+
+// Connect implements tcpip.Endpoint.Connect.
+func (ep *endpoint) Connect(addr tcpip.FullAddress) *tcpip.Error {
+	ep.mu.Lock()
+	defer ep.mu.Unlock()
+
+	if ep.closed {
+		return tcpip.ErrInvalidEndpointState
+	}
+
+	// We don't support IPv6 yet.
+	if len(addr.Addr) != header.IPv4AddressSize {
+		return tcpip.ErrInvalidEndpointState
+	}
+
+	nic := addr.NIC
+	if ep.bound {
+		if ep.boundNIC == 0 {
+			// If we're bound, but not to a specific NIC, the NIC
+			// in addr will be used. Nothing to do here.
+		} else if addr.NIC == 0 {
+			// If we're bound to a specific NIC, but addr doesn't
+			// specify a NIC, use the bound NIC.
+			nic = ep.boundNIC
+		} else if addr.NIC != ep.boundNIC {
+			// We're bound and addr specifies a NIC. They must be
+			// the same.
+			return tcpip.ErrInvalidEndpointState
+		}
+	}
+
+	// Find a route to the destination.
+	route, err := ep.stack.FindRoute(nic, tcpip.Address(""), addr.Addr, ep.netProto, false)
+	if err != nil {
+		return err
+	}
+	defer route.Release()
+
+	// Re-register the endpoint with the appropriate NIC.
+	if err := ep.stack.RegisterRawTransportEndpoint(addr.NIC, ep.netProto, ep.transProto, ep); err != nil {
+		return err
+	}
+	ep.stack.UnregisterRawTransportEndpoint(ep.registeredNIC, ep.netProto, ep.transProto, ep)
+
+	// Save the route and NIC we've connected via.
+	ep.route = route.Clone()
+	ep.registeredNIC = nic
+	ep.connected = true
+
+	return nil
+}
+
+// Shutdown implements tcpip.Endpoint.Shutdown.
+func (ep *endpoint) Shutdown(flags tcpip.ShutdownFlags) *tcpip.Error {
+	ep.mu.Lock()
+	defer ep.mu.Unlock()
+
+	if !ep.connected {
+		return tcpip.ErrNotConnected
+	}
+
+	ep.shutdownFlags |= flags
+
+	if flags&tcpip.ShutdownRead != 0 {
+		ep.rcvMu.Lock()
+		wasClosed := ep.rcvClosed
+		ep.rcvClosed = true
+		ep.rcvMu.Unlock()
+
+		if !wasClosed {
+			ep.waiterQueue.Notify(waiter.EventIn)
+		}
+	}
+
+	return nil
+}
+
+// Listen implements tcpip.Endpoint.Listen.
+func (ep *endpoint) Listen(backlog int) *tcpip.Error {
+	return tcpip.ErrNotSupported
+}
+
+// Accept implements tcpip.Endpoint.Accept.
+func (ep *endpoint) Accept() (tcpip.Endpoint, *waiter.Queue, *tcpip.Error) {
+	return nil, nil, tcpip.ErrNotSupported
+}
+
+// Bind implements tcpip.Endpoint.Bind.
+func (ep *endpoint) Bind(addr tcpip.FullAddress) *tcpip.Error {
+	ep.mu.Lock()
+	defer ep.mu.Unlock()
+
+	// Callers must provide an IPv4 address or no network address (for
+	// binding to a NIC, but not an address).
+	if len(addr.Addr) != 0 && len(addr.Addr) != 4 {
+		return tcpip.ErrInvalidEndpointState
+	}
+
+	// If a local address was specified, verify that it's valid.
+	if len(addr.Addr) == header.IPv4AddressSize && ep.stack.CheckLocalAddress(addr.NIC, ep.netProto, addr.Addr) == 0 {
+		return tcpip.ErrBadLocalAddress
+	}
+
+	// Re-register the endpoint with the appropriate NIC.
+	if err := ep.stack.RegisterRawTransportEndpoint(addr.NIC, ep.netProto, ep.transProto, ep); err != nil {
+		return err
+	}
+	ep.stack.UnregisterRawTransportEndpoint(ep.registeredNIC, ep.netProto, ep.transProto, ep)
+
+	ep.registeredNIC = addr.NIC
+	ep.boundNIC = addr.NIC
+	ep.boundAddr = addr.Addr
+	ep.bound = true
+
+	return nil
+}
+
+// GetLocalAddress implements tcpip.Endpoint.GetLocalAddress.
+func (ep *endpoint) GetLocalAddress() (tcpip.FullAddress, *tcpip.Error) {
+	return tcpip.FullAddress{}, tcpip.ErrNotSupported
+}
+
+// GetRemoteAddress implements tcpip.Endpoint.GetRemoteAddress.
+func (ep *endpoint) GetRemoteAddress() (tcpip.FullAddress, *tcpip.Error) {
+	ep.mu.RLock()
+	defer ep.mu.RUnlock()
+
+	if !ep.connected {
+		return tcpip.FullAddress{}, tcpip.ErrNotConnected
+	}
+
+	return tcpip.FullAddress{
+		NIC:  ep.registeredNIC,
+		Addr: ep.route.RemoteAddress,
+	}, nil
+}
+
+// Readiness implements tcpip.Endpoint.Readiness.
+func (ep *endpoint) Readiness(mask waiter.EventMask) waiter.EventMask {
+	// The endpoint is always writable.
+	result := waiter.EventOut & mask
+
+	// Determine whether the endpoint is readable.
+	if (mask & waiter.EventIn) != 0 {
+		ep.rcvMu.Lock()
+		if !ep.rcvList.Empty() || ep.rcvClosed {
+			result |= waiter.EventIn
+		}
+		ep.rcvMu.Unlock()
+	}
+
+	return result
+}
+
+// SetSockOpt implements tcpip.Endpoint.SetSockOpt.
+func (ep *endpoint) SetSockOpt(opt interface{}) *tcpip.Error {
+	return nil
+}
+
+// GetSockOpt implements tcpip.Endpoint.GetSockOpt.
+func (ep *endpoint) GetSockOpt(opt interface{}) *tcpip.Error {
+	switch o := opt.(type) {
+	case tcpip.ErrorOption:
+		return nil
+
+	case *tcpip.SendBufferSizeOption:
+		ep.mu.Lock()
+		*o = tcpip.SendBufferSizeOption(ep.sndBufSize)
+		ep.mu.Unlock()
+		return nil
+
+	case *tcpip.ReceiveBufferSizeOption:
+		ep.rcvMu.Lock()
+		*o = tcpip.ReceiveBufferSizeOption(ep.rcvBufSizeMax)
+		ep.rcvMu.Unlock()
+		return nil
+
+	case *tcpip.ReceiveQueueSizeOption:
+		ep.rcvMu.Lock()
+		if ep.rcvList.Empty() {
+			*o = 0
+		} else {
+			p := ep.rcvList.Front()
+			*o = tcpip.ReceiveQueueSizeOption(p.data.Size())
+		}
+		ep.rcvMu.Unlock()
+		return nil
+
+	case *tcpip.KeepaliveEnabledOption:
+		*o = 0
+		return nil
+
+	default:
+		return tcpip.ErrUnknownProtocolOption
+	}
+}
+
+// HandlePacket implements stack.RawTransportEndpoint.HandlePacket.
+func (ep *endpoint) HandlePacket(route *stack.Route, netHeader buffer.View, vv buffer.VectorisedView) {
+	ep.rcvMu.Lock()
+
+	// Drop the packet if our buffer is currently full.
+	if ep.rcvClosed || ep.rcvBufSize >= ep.rcvBufSizeMax {
+		ep.stack.Stats().DroppedPackets.Increment()
+		ep.rcvMu.Unlock()
+		return
+	}
+
+	if ep.bound {
+		// If bound to a NIC, only accept data for that NIC.
+		if ep.boundNIC != 0 && ep.boundNIC != route.NICID() {
+			ep.rcvMu.Unlock()
+			return
+		}
+		// If bound to an address, only accept data for that address.
+		if ep.boundAddr != "" && ep.boundAddr != route.RemoteAddress {
+			ep.rcvMu.Unlock()
+			return
+		}
+	}
+
+	// If connected, only accept packets from the remote address we
+	// connected to.
+	if ep.connected && ep.route.RemoteAddress != route.RemoteAddress {
+		ep.rcvMu.Unlock()
+		return
+	}
+
+	wasEmpty := ep.rcvBufSize == 0
+
+	// Push new packet into receive list and increment the buffer size.
+	packet := &packet{
+		senderAddr: tcpip.FullAddress{
+			NIC:  route.NICID(),
+			Addr: route.RemoteAddress,
+		},
+	}
+
+	combinedVV := netHeader.ToVectorisedView()
+	combinedVV.Append(vv)
+	packet.data = combinedVV.Clone(packet.views[:])
+	packet.timestampNS = ep.stack.NowNanoseconds()
+
+	ep.rcvList.PushBack(packet)
+	ep.rcvBufSize += packet.data.Size()
+
+	ep.rcvMu.Unlock()
+
+	// Notify waiters that there's data to be read.
+	if wasEmpty {
+		ep.waiterQueue.Notify(waiter.EventIn)
+	}
+}