Use specified source address for IGMP/MLD packets

This change also considers interfaces and network endpoints enabled up
up to the point all work to disable them are complete. This was needed
so that protocols can perform shutdown work while being disabled (e.g.
sending a packet which requires the endpoint to be enabled to obtain a
source address).

Bug #4682, #4861
Fixes #4888

Startblock:
  has LGTM from peterjohnston
  and then
  add reviewer brunodalbo
PiperOrigin-RevId: 346869702

3 files changed, 111 insertions, 18 deletions

diff --git a/pkg/tcpip/network/ipv4/igmp.go b/pkg/tcpip/network/ipv4/igmp.go
index a3a7176a0..fb7a9e68e 100644
--- a/pkg/tcpip/network/ipv4/igmp.go
+++ b/pkg/tcpip/network/ipv4/igmp.go
@@ -96,7 +96,9 @@ type igmpState struct {
 }
 
 // SendReport implements ip.MulticastGroupProtocol.
-func (igmp *igmpState) SendReport(groupAddress tcpip.Address) *tcpip.Error {
+//
+// Precondition: igmp.ep.mu must be read locked.
+func (igmp *igmpState) SendReport(groupAddress tcpip.Address) (bool, *tcpip.Error) {
 	igmpType := header.IGMPv2MembershipReport
 	if igmp.v1Present() {
 		igmpType = header.IGMPv1MembershipReport
@@ -105,6 +107,8 @@ func (igmp *igmpState) SendReport(groupAddress tcpip.Address) *tcpip.Error {
 }
 
 // SendLeave implements ip.MulticastGroupProtocol.
+//
+// Precondition: igmp.ep.mu must be read locked.
 func (igmp *igmpState) SendLeave(groupAddress tcpip.Address) *tcpip.Error {
 	// As per RFC 2236 Section 6, Page 8: "If the interface state says the
 	// Querier is running IGMPv1, this action SHOULD be skipped. If the flag
@@ -113,7 +117,8 @@ func (igmp *igmpState) SendLeave(groupAddress tcpip.Address) *tcpip.Error {
 	if igmp.v1Present() {
 		return nil
 	}
-	return igmp.writePacket(header.IPv4AllRoutersGroup, groupAddress, header.IGMPLeaveGroup)
+	_, err := igmp.writePacket(header.IPv4AllRoutersGroup, groupAddress, header.IGMPLeaveGroup)
+	return err
 }
 
 // init sets up an igmpState struct, and is required to be called before using
@@ -235,9 +240,10 @@ func (igmp *igmpState) handleMembershipReport(groupAddress tcpip.Address) {
 	igmp.genericMulticastProtocol.HandleReportLocked(groupAddress)
 }
 
-// writePacket assembles and sends an IGMP packet with the provided fields,
-// incrementing the provided stat counter on success.
-func (igmp *igmpState) writePacket(destAddress tcpip.Address, groupAddress tcpip.Address, igmpType header.IGMPType) *tcpip.Error {
+// writePacket assembles and sends an IGMP packet.
+//
+// Precondition: igmp.ep.mu must be read locked.
+func (igmp *igmpState) writePacket(destAddress tcpip.Address, groupAddress tcpip.Address, igmpType header.IGMPType) (bool, *tcpip.Error) {
 	igmpData := header.IGMP(buffer.NewView(header.IGMPReportMinimumSize))
 	igmpData.SetType(igmpType)
 	igmpData.SetGroupAddress(groupAddress)
@@ -248,9 +254,13 @@ func (igmp *igmpState) writePacket(destAddress tcpip.Address, groupAddress tcpip
 		Data:               buffer.View(igmpData).ToVectorisedView(),
 	})
 
-	// TODO(gvisor.dev/issue/4888): We should not use the unspecified address,
-	// rather we should select an appropriate local address.
-	localAddr := header.IPv4Any
+	addressEndpoint := igmp.ep.acquireOutgoingPrimaryAddressRLocked(destAddress, false /* allowExpired */)
+	if addressEndpoint == nil {
+		return false, nil
+	}
+	localAddr := addressEndpoint.AddressWithPrefix().Address
+	addressEndpoint.DecRef()
+	addressEndpoint = nil
 	igmp.ep.addIPHeader(localAddr, destAddress, pkt, stack.NetworkHeaderParams{
 		Protocol: header.IGMPProtocolNumber,
 		TTL:      header.IGMPTTL,
@@ -259,22 +269,22 @@ func (igmp *igmpState) writePacket(destAddress tcpip.Address, groupAddress tcpip
 		&header.IPv4SerializableRouterAlertOption{},
 	})
 
-	sent := igmp.ep.protocol.stack.Stats().IGMP.PacketsSent
+	sentStats := igmp.ep.protocol.stack.Stats().IGMP.PacketsSent
 	if err := igmp.ep.nic.WritePacketToRemote(header.EthernetAddressFromMulticastIPv4Address(destAddress), nil /* gso */, ProtocolNumber, pkt); err != nil {
-		sent.Dropped.Increment()
-		return err
+		sentStats.Dropped.Increment()
+		return false, err
 	}
 	switch igmpType {
 	case header.IGMPv1MembershipReport:
-		sent.V1MembershipReport.Increment()
+		sentStats.V1MembershipReport.Increment()
 	case header.IGMPv2MembershipReport:
-		sent.V2MembershipReport.Increment()
+		sentStats.V2MembershipReport.Increment()
 	case header.IGMPLeaveGroup:
-		sent.LeaveGroup.Increment()
+		sentStats.LeaveGroup.Increment()
 	default:
 		panic(fmt.Sprintf("unrecognized igmp type = %d", igmpType))
 	}
-	return nil
+	return true, nil
 }
 
 // joinGroup handles adding a new group to the membership map, setting up the
@@ -325,3 +335,10 @@ func (igmp *igmpState) softLeaveAll() {
 func (igmp *igmpState) initializeAll() {
 	igmp.genericMulticastProtocol.InitializeGroupsLocked()
 }
+
+// sendQueuedReports attempts to send any reports that are queued for sending.
+//
+// Precondition: igmp.ep.mu must be locked.
+func (igmp *igmpState) sendQueuedReports() {
+	igmp.genericMulticastProtocol.SendQueuedReportsLocked()
+}
diff --git a/pkg/tcpip/network/ipv4/igmp_test.go b/pkg/tcpip/network/ipv4/igmp_test.go
index 5e139377b..1ee573ac8 100644
--- a/pkg/tcpip/network/ipv4/igmp_test.go
+++ b/pkg/tcpip/network/ipv4/igmp_test.go
@@ -16,6 +16,7 @@ package ipv4_test
 
 import (
 	"testing"
+	"time"
 
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
@@ -29,6 +30,7 @@ import (
 
 const (
 	linkAddr      = tcpip.LinkAddress("\x02\x02\x03\x04\x05\x06")
+	addr          = tcpip.Address("\x0a\x00\x00\x01")
 	multicastAddr = tcpip.Address("\xe0\x00\x00\x03")
 	nicID         = 1
 )
@@ -41,6 +43,7 @@ func validateIgmpPacket(t *testing.T, p channel.PacketInfo, remoteAddress tcpip.
 
 	payload := header.IPv4(stack.PayloadSince(p.Pkt.NetworkHeader()))
 	checker.IPv4(t, payload,
+		checker.SrcAddr(addr),
 		checker.DstAddr(remoteAddress),
 		// TTL for an IGMP message must be 1 as per RFC 2236 section 2.
 		checker.TTL(1),
@@ -71,7 +74,6 @@ func createStack(t *testing.T, igmpEnabled bool) (*channel.Endpoint, *stack.Stac
 	if err := s.CreateNIC(nicID, e); err != nil {
 		t.Fatalf("CreateNIC(%d, _) = %s", nicID, err)
 	}
-
 	return e, s, clock
 }
 
@@ -104,6 +106,9 @@ func createAndInjectIGMPPacket(e *channel.Endpoint, igmpType header.IGMPType, ma
 // reports for backwards compatibility.
 func TestIgmpV1Present(t *testing.T) {
 	e, s, clock := createStack(t, true)
+	if err := s.AddAddress(nicID, ipv4.ProtocolNumber, addr); err != nil {
+		t.Fatalf("AddAddress(%d, %d, %s): %s", nicID, ipv4.ProtocolNumber, addr, err)
+	}
 
 	if err := s.JoinGroup(ipv4.ProtocolNumber, nicID, multicastAddr); err != nil {
 		t.Fatalf("JoinGroup(ipv4, nic, %s) = %s", multicastAddr, err)
@@ -154,3 +159,57 @@ func TestIgmpV1Present(t *testing.T) {
 	}
 	validateIgmpPacket(t, p, multicastAddr, header.IGMPv1MembershipReport, 0, multicastAddr)
 }
+
+func TestSendQueuedIGMPReports(t *testing.T) {
+	e, s, clock := createStack(t, true)
+
+	// Joining a group without an assigned address should queue IGMP packets; none
+	// should be sent without an assigned address.
+	if err := s.JoinGroup(ipv4.ProtocolNumber, nicID, multicastAddr); err != nil {
+		t.Fatalf("JoinGroup(%d, %d, %s): %s", ipv4.ProtocolNumber, nicID, multicastAddr, err)
+	}
+	reportStat := s.Stats().IGMP.PacketsSent.V2MembershipReport
+	if got := reportStat.Value(); got != 0 {
+		t.Errorf("got reportStat.Value() = %d, want = 0", got)
+	}
+	clock.Advance(time.Hour)
+	if p, ok := e.Read(); ok {
+		t.Fatalf("got unexpected packet = %#v", p)
+	}
+
+	// The initial set of IGMP reports that were queued should be sent once an
+	// address is assigned.
+	if err := s.AddAddress(nicID, ipv4.ProtocolNumber, addr); err != nil {
+		t.Fatalf("AddAddress(%d, %d, %s): %s", nicID, ipv4.ProtocolNumber, addr, err)
+	}
+	if got := reportStat.Value(); got != 1 {
+		t.Errorf("got reportStat.Value() = %d, want = 1", got)
+	}
+	if p, ok := e.Read(); !ok {
+		t.Error("expected to send an IGMP membership report")
+	} else {
+		validateIgmpPacket(t, p, multicastAddr, header.IGMPv2MembershipReport, 0, multicastAddr)
+	}
+	if t.Failed() {
+		t.FailNow()
+	}
+	clock.Advance(ipv4.UnsolicitedReportIntervalMax)
+	if got := reportStat.Value(); got != 2 {
+		t.Errorf("got reportStat.Value() = %d, want = 2", got)
+	}
+	if p, ok := e.Read(); !ok {
+		t.Error("expected to send an IGMP membership report")
+	} else {
+		validateIgmpPacket(t, p, multicastAddr, header.IGMPv2MembershipReport, 0, multicastAddr)
+	}
+	if t.Failed() {
+		t.FailNow()
+	}
+
+	// Should have no more packets to send after the initial set of unsolicited
+	// reports.
+	clock.Advance(time.Hour)
+	if p, ok := e.Read(); ok {
+		t.Fatalf("got unexpected packet = %#v", p)
+	}
+}
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index c63ecca4a..e9ff70d04 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -172,7 +172,7 @@ func (e *endpoint) Disable() {
 }
 
 func (e *endpoint) disableLocked() {
-	if !e.setEnabled(false) {
+	if !e.isEnabled() {
 		return
 	}
 
@@ -189,6 +189,10 @@ func (e *endpoint) disableLocked() {
 	if err := e.mu.addressableEndpointState.RemovePermanentAddress(ipv4BroadcastAddr.Address); err != nil && err != tcpip.ErrBadLocalAddress {
 		panic(fmt.Sprintf("unexpected error when removing address = %s: %s", ipv4BroadcastAddr.Address, err))
 	}
+
+	if !e.setEnabled(false) {
+		panic("should have only done work to disable the endpoint if it was enabled")
+	}
 }
 
 // DefaultTTL is the default time-to-live value for this endpoint.
@@ -780,7 +784,12 @@ func (e *endpoint) Close() {
 func (e *endpoint) AddAndAcquirePermanentAddress(addr tcpip.AddressWithPrefix, peb stack.PrimaryEndpointBehavior, configType stack.AddressConfigType, deprecated bool) (stack.AddressEndpoint, *tcpip.Error) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
-	return e.mu.addressableEndpointState.AddAndAcquirePermanentAddress(addr, peb, configType, deprecated)
+
+	ep, err := e.mu.addressableEndpointState.AddAndAcquirePermanentAddress(addr, peb, configType, deprecated)
+	if err == nil {
+		e.mu.igmp.sendQueuedReports()
+	}
+	return ep, err
 }
 
 // RemovePermanentAddress implements stack.AddressableEndpoint.
@@ -815,6 +824,14 @@ func (e *endpoint) AcquireAssignedAddress(localAddr tcpip.Address, allowTemp boo
 func (e *endpoint) AcquireOutgoingPrimaryAddress(remoteAddr tcpip.Address, allowExpired bool) stack.AddressEndpoint {
 	e.mu.RLock()
 	defer e.mu.RUnlock()
+	return e.acquireOutgoingPrimaryAddressRLocked(remoteAddr, allowExpired)
+}
+
+// acquireOutgoingPrimaryAddressRLocked is like AcquireOutgoingPrimaryAddress
+// but with locking requirements
+//
+// Precondition: igmp.ep.mu must be read locked.
+func (e *endpoint) acquireOutgoingPrimaryAddressRLocked(remoteAddr tcpip.Address, allowExpired bool) stack.AddressEndpoint {
 	return e.mu.addressableEndpointState.AcquireOutgoingPrimaryAddress(remoteAddr, allowExpired)
 }