Merge release-20201109.0-118-gbc81fcced (automated)

2 files changed, 101 insertions, 41 deletions

diff --git a/pkg/tcpip/network/ipv4/igmp.go b/pkg/tcpip/network/ipv4/igmp.go
index c9bf117de..37f1822ca 100644
--- a/pkg/tcpip/network/ipv4/igmp.go
+++ b/pkg/tcpip/network/ipv4/igmp.go
@@ -51,6 +51,16 @@ const (
 	UnsolicitedReportIntervalMax = 10 * time.Second
 )
 
+// IGMPOptions holds options for IGMP.
+type IGMPOptions struct {
+	// Enabled indicates whether IGMP will be performed.
+	//
+	// When enabled, IGMP may transmit IGMP report and leave messages when
+	// joining and leaving multicast groups respectively, and handle incoming
+	// IGMP packets.
+	Enabled bool
+}
+
 var _ ip.MulticastGroupProtocol = (*igmpState)(nil)
 
 // igmpState is the per-interface IGMP state.
@@ -58,7 +68,8 @@ var _ ip.MulticastGroupProtocol = (*igmpState)(nil)
 // igmpState.init() MUST be called after creating an IGMP state.
 type igmpState struct {
 	// The IPv4 endpoint this igmpState is for.
-	ep *endpoint
+	ep   *endpoint
+	opts IGMPOptions
 
 	// igmpV1Present is for maintaining compatibility with IGMPv1 Routers, from
 	// RFC 2236 Section 4 Page 6: "The IGMPv1 router expects Version 1
@@ -108,10 +119,11 @@ func (igmp *igmpState) SendLeave(groupAddress tcpip.Address) *tcpip.Error {
 
 // init sets up an igmpState struct, and is required to be called before using
 // a new igmpState.
-func (igmp *igmpState) init(ep *endpoint) {
+func (igmp *igmpState) init(ep *endpoint, opts IGMPOptions) {
 	igmp.mu.Lock()
 	defer igmp.mu.Unlock()
 	igmp.ep = ep
+	igmp.opts = opts
 	igmp.mu.genericMulticastProtocol.Init(ep.protocol.stack.Rand(), ep.protocol.stack.Clock(), igmp, UnsolicitedReportIntervalMax)
 	igmp.igmpV1Present = igmpV1PresentDefault
 	igmp.mu.igmpV1Job = igmp.ep.protocol.stack.NewJob(&igmp.mu, func() {
@@ -189,6 +201,10 @@ func (igmp *igmpState) setV1Present(v bool) {
 }
 
 func (igmp *igmpState) handleMembershipQuery(groupAddress tcpip.Address, maxRespTime time.Duration) {
+	if !igmp.opts.Enabled {
+		return
+	}
+
 	igmp.mu.Lock()
 	defer igmp.mu.Unlock()
 
@@ -206,6 +222,10 @@ func (igmp *igmpState) handleMembershipQuery(groupAddress tcpip.Address, maxResp
 }
 
 func (igmp *igmpState) handleMembershipReport(groupAddress tcpip.Address) {
+	if !igmp.opts.Enabled {
+		return
+	}
+
 	igmp.mu.Lock()
 	defer igmp.mu.Unlock()
 	igmp.mu.genericMulticastProtocol.HandleReport(groupAddress)
@@ -226,11 +246,8 @@ func (igmp *igmpState) writePacket(destAddress tcpip.Address, groupAddress tcpip
 
 	// TODO(gvisor.dev/issue/4888): We should not use the unspecified address,
 	// rather we should select an appropriate local address.
-	r := stack.Route{
-		LocalAddress:  header.IPv4Any,
-		RemoteAddress: destAddress,
-	}
-	igmp.ep.addIPHeader(&r, pkt, stack.NetworkHeaderParams{
+	localAddr := header.IPv4Any
+	igmp.ep.addIPHeader(localAddr, destAddress, pkt, stack.NetworkHeaderParams{
 		Protocol: header.IGMPProtocolNumber,
 		TTL:      header.IGMPTTL,
 		TOS:      stack.DefaultTOS,
@@ -239,7 +256,7 @@ func (igmp *igmpState) writePacket(destAddress tcpip.Address, groupAddress tcpip
 	// TODO(b/162198658): set the ROUTER_ALERT option when sending Host
 	// Membership Reports.
 	sent := igmp.ep.protocol.stack.Stats().IGMP.PacketsSent
-	if err := igmp.ep.nic.WritePacketToRemote(header.EthernetAddressFromMulticastIPv4Address(destAddress), nil /* gso */, header.IPv4ProtocolNumber, pkt); err != nil {
+	if err := igmp.ep.nic.WritePacketToRemote(header.EthernetAddressFromMulticastIPv4Address(destAddress), nil /* gso */, ProtocolNumber, pkt); err != nil {
 		sent.Dropped.Increment()
 		return err
 	}
@@ -263,6 +280,26 @@ func (igmp *igmpState) writePacket(destAddress tcpip.Address, groupAddress tcpip
 // If the group already exists in the membership map, returns
 // tcpip.ErrDuplicateAddress.
 func (igmp *igmpState) joinGroup(groupAddress tcpip.Address) *tcpip.Error {
+	if !igmp.opts.Enabled {
+		return nil
+	}
+
+	// As per RFC 2236 section 6 page 10,
+	//
+	//   The all-systems group (address 224.0.0.1) is handled as a special
+	//   case. The host starts in Idle Member state for that group on every
+	//   interface, never transitions to another state, and never sends a
+	//   report for that group.
+	//
+	// This is equivalent to not performing IGMP for the all-systems multicast
+	// address. Simply not performing IGMP when the group is added will prevent
+	// any work from being done on the all-systems multicast group when leaving
+	// the group or when query or report messages are received for it since the
+	// MGP state will not know about it.
+	if groupAddress == header.IPv4AllSystems {
+		return nil
+	}
+
 	igmp.mu.Lock()
 	defer igmp.mu.Unlock()
 
@@ -280,6 +317,10 @@ func (igmp *igmpState) joinGroup(groupAddress tcpip.Address) *tcpip.Error {
 // If the group does not exist in the membership map, this function will
 // silently return.
 func (igmp *igmpState) leaveGroup(groupAddress tcpip.Address) {
+	if !igmp.opts.Enabled {
+		return
+	}
+
 	igmp.mu.Lock()
 	defer igmp.mu.Unlock()
 	igmp.mu.genericMulticastProtocol.LeaveGroup(groupAddress)
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index 7c759be9a..be9c8e2f9 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -95,7 +95,7 @@ func (p *protocol) NewEndpoint(nic stack.NetworkInterface, _ stack.LinkAddressCa
 		protocol:   p,
 	}
 	e.mu.addressableEndpointState.Init(e)
-	e.igmp.init(e)
+	e.igmp.init(e, p.options.IGMP)
 	return e
 }
 
@@ -126,7 +126,7 @@ func (e *endpoint) Enable() *tcpip.Error {
 	// As per RFC 1122 section 3.3.7, all hosts should join the all-hosts
 	// multicast group. Note, the IANA calls the all-hosts multicast group the
 	// all-systems multicast group.
-	_, err = e.mu.addressableEndpointState.JoinGroup(header.IPv4AllSystems)
+	_, err = e.joinGroupLocked(header.IPv4AllSystems)
 	return err
 }
 
@@ -164,7 +164,7 @@ func (e *endpoint) disableLocked() {
 	}
 
 	// The endpoint may have already left the multicast group.
-	if _, err := e.mu.addressableEndpointState.LeaveGroup(header.IPv4AllSystems); err != nil && err != tcpip.ErrBadLocalAddress {
+	if _, err := e.leaveGroupLocked(header.IPv4AllSystems); err != nil && err != tcpip.ErrBadLocalAddress {
 		panic(fmt.Sprintf("unexpected error when leaving group = %s: %s", header.IPv4AllSystems, err))
 	}
 
@@ -200,7 +200,7 @@ func (e *endpoint) NetworkProtocolNumber() tcpip.NetworkProtocolNumber {
 	return e.protocol.Number()
 }
 
-func (e *endpoint) addIPHeader(r *stack.Route, pkt *stack.PacketBuffer, params stack.NetworkHeaderParams) {
+func (e *endpoint) addIPHeader(srcAddr, dstAddr tcpip.Address, pkt *stack.PacketBuffer, params stack.NetworkHeaderParams) {
 	hdrLen := header.IPv4MinimumSize
 	var opts header.IPv4Options
 	if params.Options != nil {
@@ -221,15 +221,15 @@ func (e *endpoint) addIPHeader(r *stack.Route, pkt *stack.PacketBuffer, params s
 	// RFC 6864 section 4.3 mandates uniqueness of ID values for non-atomic
 	// datagrams. Since the DF bit is never being set here, all datagrams
 	// are non-atomic and need an ID.
-	id := atomic.AddUint32(&e.protocol.ids[hashRoute(r, params.Protocol, e.protocol.hashIV)%buckets], 1)
+	id := atomic.AddUint32(&e.protocol.ids[hashRoute(srcAddr, dstAddr, params.Protocol, e.protocol.hashIV)%buckets], 1)
 	ip.Encode(&header.IPv4Fields{
 		TotalLength: length,
 		ID:          uint16(id),
 		TTL:         params.TTL,
 		TOS:         params.TOS,
 		Protocol:    uint8(params.Protocol),
-		SrcAddr:     r.LocalAddress,
-		DstAddr:     r.RemoteAddress,
+		SrcAddr:     srcAddr,
+		DstAddr:     dstAddr,
 		Options:     opts,
 	})
 	ip.SetChecksum(^ip.CalculateChecksum())
@@ -261,7 +261,7 @@ func (e *endpoint) handleFragments(r *stack.Route, gso *stack.GSO, networkMTU ui
 
 // WritePacket writes a packet to the given destination address and protocol.
 func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.NetworkHeaderParams, pkt *stack.PacketBuffer) *tcpip.Error {
-	e.addIPHeader(r, pkt, params)
+	e.addIPHeader(r.LocalAddress, r.RemoteAddress, pkt, params)
 
 	// iptables filtering. All packets that reach here are locally
 	// generated.
@@ -349,7 +349,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
 	}
 
 	for pkt := pkts.Front(); pkt != nil; pkt = pkt.Next() {
-		e.addIPHeader(r, pkt, params)
+		e.addIPHeader(r.LocalAddress, r.RemoteAddress, pkt, params)
 		networkMTU, err := calculateNetworkMTU(e.nic.MTU(), uint32(pkt.NetworkHeader().View().Size()))
 		if err != nil {
 			r.Stats().IP.OutgoingPacketErrors.IncrementBy(uint64(pkts.Len()))
@@ -463,7 +463,7 @@ func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBu
 		// non-atomic datagrams, so assign an ID to all such datagrams
 		// according to the definition given in RFC 6864 section 4.
 		if ip.Flags()&header.IPv4FlagDontFragment == 0 || ip.Flags()&header.IPv4FlagMoreFragments != 0 || ip.FragmentOffset() > 0 {
-			ip.SetID(uint16(atomic.AddUint32(&e.protocol.ids[hashRoute(r, 0 /* protocol */, e.protocol.hashIV)%buckets], 1)))
+			ip.SetID(uint16(atomic.AddUint32(&e.protocol.ids[hashRoute(r.LocalAddress, r.RemoteAddress, 0 /* protocol */, e.protocol.hashIV)%buckets], 1)))
 		}
 	}
 
@@ -706,10 +706,7 @@ func (e *endpoint) handlePacket(pkt *stack.PacketBuffer) {
 		return
 	}
 	if p == header.IGMPProtocolNumber {
-		if e.protocol.options.IGMPEnabled {
-			e.igmp.handleIGMP(pkt)
-		}
-		// Nothing further to do with an IGMP packet, even if IGMP is not enabled.
+		e.igmp.handleIGMP(pkt)
 		return
 	}
 	if opts := h.Options(); len(opts) != 0 {
@@ -837,32 +834,55 @@ func (e *endpoint) PermanentAddresses() []tcpip.AddressWithPrefix {
 
 // JoinGroup implements stack.GroupAddressableEndpoint.
 func (e *endpoint) JoinGroup(addr tcpip.Address) (bool, *tcpip.Error) {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	return e.joinGroupLocked(addr)
+}
+
+// joinGroupLocked is like JoinGroup, but with locking requirements.
+//
+// Precondition: e.mu must be locked.
+func (e *endpoint) joinGroupLocked(addr tcpip.Address) (bool, *tcpip.Error) {
 	if !header.IsV4MulticastAddress(addr) {
 		return false, tcpip.ErrBadAddress
 	}
+	// TODO(gvisor.dev/issue/4916): Keep track of join count and IGMP state in a
+	// single type.
+	joined, err := e.mu.addressableEndpointState.JoinGroup(addr)
+	if err != nil || !joined {
+		return joined, err
+	}
 
-	e.mu.Lock()
-	defer e.mu.Unlock()
-
-	joinedGroup, err := e.mu.addressableEndpointState.JoinGroup(addr)
-	if err == nil && joinedGroup && e.protocol.options.IGMPEnabled {
-		_ = e.igmp.joinGroup(addr)
+	// joinGroup only returns an error if we try to join a group twice, but we
+	// checked above to make sure that the group was newly joined.
+	if err := e.igmp.joinGroup(addr); err != nil {
+		panic(fmt.Sprintf("e.igmp.joinGroup(%s): %s", addr, err))
 	}
 
-	return joinedGroup, err
+	return true, nil
 }
 
 // LeaveGroup implements stack.GroupAddressableEndpoint.
 func (e *endpoint) LeaveGroup(addr tcpip.Address) (bool, *tcpip.Error) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
+	return e.leaveGroupLocked(addr)
+}
+
+// leaveGroupLocked is like LeaveGroup, but with locking requirements.
+//
+// Precondition: e.mu must be locked.
+func (e *endpoint) leaveGroupLocked(addr tcpip.Address) (bool, *tcpip.Error) {
+	left, err := e.mu.addressableEndpointState.LeaveGroup(addr)
+	if err != nil {
+		return left, err
+	}
 
-	leftGroup, err := e.mu.addressableEndpointState.LeaveGroup(addr)
-	if err == nil && leftGroup && e.protocol.options.IGMPEnabled {
+	if left {
 		e.igmp.leaveGroup(addr)
 	}
 
-	return leftGroup, err
+	return left, nil
 }
 
 // IsInGroup implements stack.GroupAddressableEndpoint.
@@ -1021,20 +1041,19 @@ func addressToUint32(addr tcpip.Address) uint32 {
 	return uint32(addr[0]) | uint32(addr[1])<<8 | uint32(addr[2])<<16 | uint32(addr[3])<<24
 }
 
-// hashRoute calculates a hash value for the given route. It uses the source &
-// destination address, the transport protocol number and a 32-bit number to
-// generate the hash.
-func hashRoute(r *stack.Route, protocol tcpip.TransportProtocolNumber, hashIV uint32) uint32 {
-	a := addressToUint32(r.LocalAddress)
-	b := addressToUint32(r.RemoteAddress)
+// hashRoute calculates a hash value for the given source/destination pair using
+// the addresses, transport protocol number and a 32-bit number to generate the
+// hash.
+func hashRoute(srcAddr, dstAddr tcpip.Address, protocol tcpip.TransportProtocolNumber, hashIV uint32) uint32 {
+	a := addressToUint32(srcAddr)
+	b := addressToUint32(dstAddr)
 	return hash.Hash3Words(a, b, uint32(protocol), hashIV)
 }
 
 // Options holds options to configure a new protocol.
 type Options struct {
-	// IGMPEnabled indicates whether incoming IGMP packets will be handled and if
-	// this endpoint will transmit IGMP packets on IGMP related events.
-	IGMPEnabled bool
+	// IGMP holds options for IGMP.
+	IGMP IGMPOptions
 }
 
 // NewProtocolWithOptions returns an IPv4 network protocol.