Merge release-20201130.0-69-g50189b0d6 (automated)

3 files changed, 23 insertions, 7 deletions

diff --git a/pkg/tcpip/network/ip/generic_multicast_protocol.go b/pkg/tcpip/network/ip/generic_multicast_protocol.go
index bc7f7f637..c8c17ab15 100644
--- a/pkg/tcpip/network/ip/generic_multicast_protocol.go
+++ b/pkg/tcpip/network/ip/generic_multicast_protocol.go
@@ -161,7 +161,8 @@ type GenericMulticastProtocolState struct {
 
 // Init initializes the Generic Multicast Protocol state.
 //
-// Must only be called once for the lifetime of g.
+// Must only be called once for the lifetime of g; Init will panic if it is
+// called twice.
 //
 // The GenericMulticastProtocolState will only grab the lock when timers/jobs
 // fire.
@@ -170,9 +171,11 @@ func (g *GenericMulticastProtocolState) Init(protocolMU *sync.RWMutex, opts Gene
 		panic("attempted to initialize generic membership protocol state twice")
 	}
 
-	g.opts = opts
-	g.memberships = make(map[tcpip.Address]multicastGroupState)
-	g.protocolMU = protocolMU
+	*g = GenericMulticastProtocolState{
+		opts:        opts,
+		memberships: make(map[tcpip.Address]multicastGroupState),
+		protocolMU:  protocolMU,
+	}
 }
 
 // MakeAllNonMemberLocked transitions all groups to the non-member state.
diff --git a/pkg/tcpip/network/ipv4/igmp.go b/pkg/tcpip/network/ipv4/igmp.go
index 2ee4c6445..a3a7176a0 100644
--- a/pkg/tcpip/network/ipv4/igmp.go
+++ b/pkg/tcpip/network/ipv4/igmp.go
@@ -57,6 +57,9 @@ type IGMPOptions struct {
 	// When enabled, IGMP may transmit IGMP report and leave messages when
 	// joining and leaving multicast groups respectively, and handle incoming
 	// IGMP packets.
+	//
+	// This field is ignored and is always assumed to be false for interfaces
+	// without neighbouring nodes (e.g. loopback).
 	Enabled bool
 }
 
@@ -69,6 +72,8 @@ type igmpState struct {
 	// The IPv4 endpoint this igmpState is for.
 	ep *endpoint
 
+	enabled bool
+
 	genericMulticastProtocol ip.GenericMulticastProtocolState
 
 	// igmpV1Present is for maintaining compatibility with IGMPv1 Routers, from
@@ -117,8 +122,11 @@ func (igmp *igmpState) SendLeave(groupAddress tcpip.Address) *tcpip.Error {
 // Must only be called once for the lifetime of igmp.
 func (igmp *igmpState) init(ep *endpoint) {
 	igmp.ep = ep
+	// No need to perform IGMP on loopback interfaces since they don't have
+	// neighbouring nodes.
+	igmp.enabled = ep.protocol.options.IGMP.Enabled && !igmp.ep.nic.IsLoopback()
 	igmp.genericMulticastProtocol.Init(&ep.mu.RWMutex, ip.GenericMulticastProtocolOptions{
-		Enabled:                   ep.protocol.options.IGMP.Enabled,
+		Enabled:                   igmp.enabled,
 		Rand:                      ep.protocol.stack.Rand(),
 		Clock:                     ep.protocol.stack.Clock(),
 		Protocol:                  igmp,
@@ -210,7 +218,7 @@ func (igmp *igmpState) handleMembershipQuery(groupAddress tcpip.Address, maxResp
 	// As per RFC 2236 Section 6, Page 10: If the maximum response time is zero
 	// then change the state to note that an IGMPv1 router is present and
 	// schedule the query received Job.
-	if maxRespTime == 0 && igmp.ep.protocol.options.IGMP.Enabled {
+	if igmp.enabled && maxRespTime == 0 {
 		igmp.igmpV1Job.Cancel()
 		igmp.igmpV1Job.Schedule(v1RouterPresentTimeout)
 		igmp.setV1Present(true)
diff --git a/pkg/tcpip/network/ipv6/mld.go b/pkg/tcpip/network/ipv6/mld.go
index 6face17c6..b67eafdba 100644
--- a/pkg/tcpip/network/ipv6/mld.go
+++ b/pkg/tcpip/network/ipv6/mld.go
@@ -40,6 +40,9 @@ type MLDOptions struct {
 	// When enabled, MLD may transmit MLD report and done messages when
 	// joining and leaving multicast groups respectively, and handle incoming
 	// MLD packets.
+	//
+	// This field is ignored and is always assumed to be false for interfaces
+	// without neighbouring nodes (e.g. loopback).
 	Enabled bool
 }
 
@@ -72,7 +75,9 @@ func (mld *mldState) SendLeave(groupAddress tcpip.Address) *tcpip.Error {
 func (mld *mldState) init(ep *endpoint) {
 	mld.ep = ep
 	mld.genericMulticastProtocol.Init(&ep.mu.RWMutex, ip.GenericMulticastProtocolOptions{
-		Enabled:                   ep.protocol.options.MLD.Enabled,
+		// No need to perform MLD on loopback interfaces since they don't have
+		// neighbouring nodes.
+		Enabled:                   ep.protocol.options.MLD.Enabled && !mld.ep.nic.IsLoopback(),
 		Rand:                      ep.protocol.stack.Rand(),
 		Clock:                     ep.protocol.stack.Clock(),
 		Protocol:                  mld,