From 5bc4ae9d5746e65909a0bdab60e7bd598d4401c7 Mon Sep 17 00:00:00 2001
From: Ghanan Gowripalan <ghanan@google.com>
Date: Mon, 23 Dec 2019 08:53:57 -0800
Subject: Clear any host-specific NDP state when becoming a router
This change supports clearing all host-only NDP state when NICs become routers.
All discovered routers, discovered on-link prefixes and auto-generated addresses
will be invalidated when becoming a router. This is because normally, routers do
not process Router Advertisements to discover routers or on-link prefixes, and
do not do SLAAC.
Tests: Unittest to make sure that all discovered routers, discovered prefixes
and auto-generated addresses get invalidated when transitioning from a host to
a router.
PiperOrigin-RevId: 286902309
---
pkg/tcpip/stack/ndp.go | 35 ++++++
pkg/tcpip/stack/ndp_test.go | 283 ++++++++++++++++++++++++++++++++++++++++++--
pkg/tcpip/stack/nic.go | 12 ++
pkg/tcpip/stack/stack.go | 22 +++-
4 files changed, 338 insertions(+), 14 deletions(-)
(limited to 'pkg/tcpip')
diff --git a/pkg/tcpip/stack/ndp.go b/pkg/tcpip/stack/ndp.go
index 90664ba8a..d9ab59336 100644
--- a/pkg/tcpip/stack/ndp.go
+++ b/pkg/tcpip/stack/ndp.go
@@ -1155,3 +1155,38 @@ func (ndp *ndpState) autoGenAddrInvalidationTimer(addr tcpip.Address, vl time.Du
ndp.invalidateAutoGenAddress(addr)
})
}
+
+// cleanupHostOnlyState cleans up any state that is only useful for hosts.
+//
+// cleanupHostOnlyState MUST be called when ndp's NIC is transitioning from a
+// host to a router. This function will invalidate all discovered on-link
+// prefixes, discovered routers, and auto-generated addresses as routers do not
+// normally process Router Advertisements to discover default routers and
+// on-link prefixes, and auto-generate addresses via SLAAC.
+//
+// The NIC that ndp belongs to MUST be locked.
+func (ndp *ndpState) cleanupHostOnlyState() {
+ for addr, _ := range ndp.autoGenAddresses {
+ ndp.invalidateAutoGenAddress(addr)
+ }
+
+ if got := len(ndp.autoGenAddresses); got != 0 {
+ log.Fatalf("ndp: still have auto-generated addresses after cleaning up, found = %d", got)
+ }
+
+ for prefix, _ := range ndp.onLinkPrefixes {
+ ndp.invalidateOnLinkPrefix(prefix)
+ }
+
+ if got := len(ndp.onLinkPrefixes); got != 0 {
+ log.Fatalf("ndp: still have discovered on-link prefixes after cleaning up, found = %d", got)
+ }
+
+ for router, _ := range ndp.defaultRouters {
+ ndp.invalidateDefaultRouter(router)
+ }
+
+ if got := len(ndp.defaultRouters); got != 0 {
+ log.Fatalf("ndp: still have discovered default routers after cleaning up, found = %d", got)
+ }
+}
diff --git a/pkg/tcpip/stack/ndp_test.go b/pkg/tcpip/stack/ndp_test.go
index 666f86c33..64a9a2b20 100644
--- a/pkg/tcpip/stack/ndp_test.go
+++ b/pkg/tcpip/stack/ndp_test.go
@@ -47,6 +47,19 @@ var (
llAddr3 = header.LinkLocalAddr(linkAddr3)
)
+func addrForSubnet(subnet tcpip.Subnet, linkAddr tcpip.LinkAddress) tcpip.AddressWithPrefix {
+ if !header.IsValidUnicastEthernetAddress(linkAddr) {
+ return tcpip.AddressWithPrefix{}
+ }
+
+ addrBytes := []byte(subnet.ID())
+ header.EthernetAdddressToModifiedEUI64IntoBuf(linkAddr, addrBytes[header.IIDOffsetInIPv6Address:])
+ return tcpip.AddressWithPrefix{
+ Address: tcpip.Address(addrBytes),
+ PrefixLen: 64,
+ }
+}
+
// prefixSubnetAddr returns a prefix (Address + Length), the prefix's equivalent
// tcpip.Subnet, and an address where the lower half of the address is composed
// of the EUI-64 of linkAddr if it is a valid unicast ethernet address.
@@ -59,17 +72,7 @@ func prefixSubnetAddr(offset uint8, linkAddr tcpip.LinkAddress) (tcpip.AddressWi
subnet := prefix.Subnet()
- var addr tcpip.AddressWithPrefix
- if header.IsValidUnicastEthernetAddress(linkAddr) {
- addrBytes := []byte(subnet.ID())
- header.EthernetAdddressToModifiedEUI64IntoBuf(linkAddr, addrBytes[header.IIDOffsetInIPv6Address:])
- addr = tcpip.AddressWithPrefix{
- Address: tcpip.Address(addrBytes),
- PrefixLen: 64,
- }
- }
-
- return prefix, subnet, addr
+ return prefix, subnet, addrForSubnet(subnet, linkAddr)
}
// TestDADDisabled tests that an address successfully resolves immediately
@@ -1772,7 +1775,7 @@ func TestAutoGenAddrValidLifetimeUpdates(t *testing.T) {
// test.evl.
select {
case <-ndpDisp.autoGenAddrC:
- t.Fatalf("unexpectedly received an auto gen addr event")
+ t.Fatal("unexpectedly received an auto gen addr event")
case <-time.After(time.Duration(test.evl)*time.Second - delta):
}
@@ -1846,7 +1849,7 @@ func TestAutoGenAddrRemoval(t *testing.T) {
// got stopped/cleaned up.
select {
case <-ndpDisp.autoGenAddrC:
- t.Fatalf("unexpectedly received an auto gen addr event")
+ t.Fatal("unexpectedly received an auto gen addr event")
case <-time.After(lifetimeSeconds*time.Second + defaultTimeout):
}
}
@@ -2055,3 +2058,257 @@ func TestNDPRecursiveDNSServerDispatch(t *testing.T) {
})
}
}
+
+// TestCleanupHostOnlyStateOnBecomingRouter tests that all discovered routers
+// and prefixes, and auto-generated addresses get invalidated when a NIC
+// becomes a router.
+func TestCleanupHostOnlyStateOnBecomingRouter(t *testing.T) {
+ t.Parallel()
+
+ const (
+ lifetimeSeconds = 5
+ maxEvents = 4
+ nicID1 = 1
+ nicID2 = 2
+ )
+
+ prefix1, subnet1, e1Addr1 := prefixSubnetAddr(0, linkAddr1)
+ prefix2, subnet2, e1Addr2 := prefixSubnetAddr(1, linkAddr1)
+ e2Addr1 := addrForSubnet(subnet1, linkAddr2)
+ e2Addr2 := addrForSubnet(subnet2, linkAddr2)
+
+ ndpDisp := ndpDispatcher{
+ routerC: make(chan ndpRouterEvent, maxEvents),
+ rememberRouter: true,
+ prefixC: make(chan ndpPrefixEvent, maxEvents),
+ rememberPrefix: true,
+ autoGenAddrC: make(chan ndpAutoGenAddrEvent, maxEvents),
+ }
+ s := stack.New(stack.Options{
+ NetworkProtocols: []stack.NetworkProtocol{ipv6.NewProtocol()},
+ NDPConfigs: stack.NDPConfigurations{
+ HandleRAs: true,
+ DiscoverDefaultRouters: true,
+ DiscoverOnLinkPrefixes: true,
+ AutoGenGlobalAddresses: true,
+ },
+ NDPDisp: &ndpDisp,
+ })
+
+ e1 := channel.New(0, 1280, linkAddr1)
+ if err := s.CreateNIC(nicID1, e1); err != nil {
+ t.Fatalf("CreateNIC(%d, _) = %s", nicID1, err)
+ }
+
+ e2 := channel.New(0, 1280, linkAddr2)
+ if err := s.CreateNIC(nicID2, e2); err != nil {
+ t.Fatalf("CreateNIC(%d, _) = %s", nicID2, err)
+ }
+
+ expectRouterEvent := func() (bool, ndpRouterEvent) {
+ select {
+ case e := <-ndpDisp.routerC:
+ return true, e
+ default:
+ }
+
+ return false, ndpRouterEvent{}
+ }
+
+ expectPrefixEvent := func() (bool, ndpPrefixEvent) {
+ select {
+ case e := <-ndpDisp.prefixC:
+ return true, e
+ default:
+ }
+
+ return false, ndpPrefixEvent{}
+ }
+
+ expectAutoGenAddrEvent := func() (bool, ndpAutoGenAddrEvent) {
+ select {
+ case e := <-ndpDisp.autoGenAddrC:
+ return true, e
+ default:
+ }
+
+ return false, ndpAutoGenAddrEvent{}
+ }
+
+ // Receive RAs on NIC(1) and NIC(2) from default routers (llAddr1 and
+ // llAddr2) w/ PI (for prefix1 in RA from llAddr1 and prefix2 in RA from
+ // llAddr2) to discover multiple routers and prefixes, and auto-gen
+ // multiple addresses.
+
+ e1.InjectInbound(header.IPv6ProtocolNumber, raBufWithPI(llAddr1, lifetimeSeconds, prefix1, true, true, lifetimeSeconds, lifetimeSeconds))
+ // We have other tests that make sure we receive the *correct* events
+ // on normal discovery of routers/prefixes, and auto-generated
+ // addresses. Here we just make sure we get an event and let other tests
+ // handle the correctness check.
+ if ok, _ := expectRouterEvent(); !ok {
+ t.Errorf("expected router event for %s on NIC(%d)", llAddr1, nicID1)
+ }
+ if ok, _ := expectPrefixEvent(); !ok {
+ t.Errorf("expected prefix event for %s on NIC(%d)", prefix1, nicID1)
+ }
+ if ok, _ := expectAutoGenAddrEvent(); !ok {
+ t.Errorf("expected auto-gen addr event for %s on NIC(%d)", e1Addr1, nicID1)
+ }
+
+ e1.InjectInbound(header.IPv6ProtocolNumber, raBufWithPI(llAddr2, lifetimeSeconds, prefix2, true, true, lifetimeSeconds, lifetimeSeconds))
+ if ok, _ := expectRouterEvent(); !ok {
+ t.Errorf("expected router event for %s on NIC(%d)", llAddr2, nicID1)
+ }
+ if ok, _ := expectPrefixEvent(); !ok {
+ t.Errorf("expected prefix event for %s on NIC(%d)", prefix2, nicID1)
+ }
+ if ok, _ := expectAutoGenAddrEvent(); !ok {
+ t.Errorf("expected auto-gen addr event for %s on NIC(%d)", e1Addr2, nicID1)
+ }
+
+ e2.InjectInbound(header.IPv6ProtocolNumber, raBufWithPI(llAddr1, lifetimeSeconds, prefix1, true, true, lifetimeSeconds, lifetimeSeconds))
+ if ok, _ := expectRouterEvent(); !ok {
+ t.Errorf("expected router event for %s on NIC(%d)", llAddr1, nicID2)
+ }
+ if ok, _ := expectPrefixEvent(); !ok {
+ t.Errorf("expected prefix event for %s on NIC(%d)", prefix1, nicID2)
+ }
+ if ok, _ := expectAutoGenAddrEvent(); !ok {
+ t.Errorf("expected auto-gen addr event for %s on NIC(%d)", e1Addr2, nicID2)
+ }
+
+ e2.InjectInbound(header.IPv6ProtocolNumber, raBufWithPI(llAddr2, lifetimeSeconds, prefix2, true, true, lifetimeSeconds, lifetimeSeconds))
+ if ok, _ := expectRouterEvent(); !ok {
+ t.Errorf("expected router event for %s on NIC(%d)", llAddr2, nicID2)
+ }
+ if ok, _ := expectPrefixEvent(); !ok {
+ t.Errorf("expected prefix event for %s on NIC(%d)", prefix2, nicID2)
+ }
+ if ok, _ := expectAutoGenAddrEvent(); !ok {
+ t.Errorf("expected auto-gen addr event for %s on NIC(%d)", e2Addr2, nicID2)
+ }
+
+ // We should have the auto-generated addresses added.
+ nicinfo := s.NICInfo()
+ nic1Addrs := nicinfo[nicID1].ProtocolAddresses
+ nic2Addrs := nicinfo[nicID2].ProtocolAddresses
+ if !contains(nic1Addrs, e1Addr1) {
+ t.Errorf("missing %s from the list of addresses for NIC(%d): %+v", e1Addr1, nicID1, nic1Addrs)
+ }
+ if !contains(nic1Addrs, e1Addr2) {
+ t.Errorf("missing %s from the list of addresses for NIC(%d): %+v", e1Addr2, nicID1, nic1Addrs)
+ }
+ if !contains(nic2Addrs, e2Addr1) {
+ t.Errorf("missing %s from the list of addresses for NIC(%d): %+v", e2Addr1, nicID2, nic2Addrs)
+ }
+ if !contains(nic2Addrs, e2Addr2) {
+ t.Errorf("missing %s from the list of addresses for NIC(%d): %+v", e2Addr2, nicID2, nic2Addrs)
+ }
+
+ // We can't proceed any further if we already failed the test (missing
+ // some discovery/auto-generated address events or addresses).
+ if t.Failed() {
+ t.FailNow()
+ }
+
+ s.SetForwarding(true)
+
+ // Collect invalidation events after becoming a router
+ gotRouterEvents := make(map[ndpRouterEvent]int)
+ for i := 0; i < maxEvents; i++ {
+ ok, e := expectRouterEvent()
+ if !ok {
+ t.Errorf("expected %d router events after becoming a router; got = %d", maxEvents, i)
+ break
+ }
+ gotRouterEvents[e]++
+ }
+ gotPrefixEvents := make(map[ndpPrefixEvent]int)
+ for i := 0; i < maxEvents; i++ {
+ ok, e := expectPrefixEvent()
+ if !ok {
+ t.Errorf("expected %d prefix events after becoming a router; got = %d", maxEvents, i)
+ break
+ }
+ gotPrefixEvents[e]++
+ }
+ gotAutoGenAddrEvents := make(map[ndpAutoGenAddrEvent]int)
+ for i := 0; i < maxEvents; i++ {
+ ok, e := expectAutoGenAddrEvent()
+ if !ok {
+ t.Errorf("expected %d auto-generated address events after becoming a router; got = %d", maxEvents, i)
+ break
+ }
+ gotAutoGenAddrEvents[e]++
+ }
+
+ // No need to proceed any further if we already failed the test (missing
+ // some invalidation events).
+ if t.Failed() {
+ t.FailNow()
+ }
+
+ expectedRouterEvents := map[ndpRouterEvent]int{
+ {nicID: nicID1, addr: llAddr1, discovered: false}: 1,
+ {nicID: nicID1, addr: llAddr2, discovered: false}: 1,
+ {nicID: nicID2, addr: llAddr1, discovered: false}: 1,
+ {nicID: nicID2, addr: llAddr2, discovered: false}: 1,
+ }
+ if diff := cmp.Diff(expectedRouterEvents, gotRouterEvents); diff != "" {
+ t.Errorf("router events mismatch (-want +got):\n%s", diff)
+ }
+ expectedPrefixEvents := map[ndpPrefixEvent]int{
+ {nicID: nicID1, prefix: subnet1, discovered: false}: 1,
+ {nicID: nicID1, prefix: subnet2, discovered: false}: 1,
+ {nicID: nicID2, prefix: subnet1, discovered: false}: 1,
+ {nicID: nicID2, prefix: subnet2, discovered: false}: 1,
+ }
+ if diff := cmp.Diff(expectedPrefixEvents, gotPrefixEvents); diff != "" {
+ t.Errorf("prefix events mismatch (-want +got):\n%s", diff)
+ }
+ expectedAutoGenAddrEvents := map[ndpAutoGenAddrEvent]int{
+ {nicID: nicID1, addr: e1Addr1, eventType: invalidatedAddr}: 1,
+ {nicID: nicID1, addr: e1Addr2, eventType: invalidatedAddr}: 1,
+ {nicID: nicID2, addr: e2Addr1, eventType: invalidatedAddr}: 1,
+ {nicID: nicID2, addr: e2Addr2, eventType: invalidatedAddr}: 1,
+ }
+ if diff := cmp.Diff(expectedAutoGenAddrEvents, gotAutoGenAddrEvents); diff != "" {
+ t.Errorf("auto-generated address events mismatch (-want +got):\n%s", diff)
+ }
+
+ // Make sure the auto-generated addresses got removed.
+ nicinfo = s.NICInfo()
+ nic1Addrs = nicinfo[nicID1].ProtocolAddresses
+ nic2Addrs = nicinfo[nicID2].ProtocolAddresses
+ if contains(nic1Addrs, e1Addr1) {
+ t.Errorf("still have %s in the list of addresses for NIC(%d): %+v", e1Addr1, nicID1, nic1Addrs)
+ }
+ if contains(nic1Addrs, e1Addr2) {
+ t.Errorf("still have %s in the list of addresses for NIC(%d): %+v", e1Addr2, nicID1, nic1Addrs)
+ }
+ if contains(nic2Addrs, e2Addr1) {
+ t.Errorf("still have %s in the list of addresses for NIC(%d): %+v", e2Addr1, nicID2, nic2Addrs)
+ }
+ if contains(nic2Addrs, e2Addr2) {
+ t.Errorf("still have %s in the list of addresses for NIC(%d): %+v", e2Addr2, nicID2, nic2Addrs)
+ }
+
+ // Should not get any more events (invalidation timers should have been
+ // cancelled when we transitioned into a router).
+ time.Sleep(lifetimeSeconds*time.Second + defaultTimeout)
+ select {
+ case <-ndpDisp.routerC:
+ t.Error("unexpected router event")
+ default:
+ }
+ select {
+ case <-ndpDisp.prefixC:
+ t.Error("unexpected prefix event")
+ default:
+ }
+ select {
+ case <-ndpDisp.autoGenAddrC:
+ t.Error("unexpected auto-generated address event")
+ default:
+ }
+}
diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go
index e8401c673..ddd014658 100644
--- a/pkg/tcpip/stack/nic.go
+++ b/pkg/tcpip/stack/nic.go
@@ -203,6 +203,18 @@ func (n *NIC) enable() *tcpip.Error {
return err
}
+// becomeIPv6Router transitions n into an IPv6 router.
+//
+// When transitioning into an IPv6 router, host-only state (NDP discovered
+// routers, discovered on-link prefixes, and auto-generated addresses) will
+// be cleaned up/invalidated.
+func (n *NIC) becomeIPv6Router() {
+ n.mu.Lock()
+ defer n.mu.Unlock()
+
+ n.ndp.cleanupHostOnlyState()
+}
+
// attachLinkEndpoint attaches the NIC to the endpoint, which will enable it
// to start delivering packets.
func (n *NIC) attachLinkEndpoint() {
diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go
index 0e88643a4..7a9600679 100644
--- a/pkg/tcpip/stack/stack.go
+++ b/pkg/tcpip/stack/stack.go
@@ -662,11 +662,31 @@ func (s *Stack) Stats() tcpip.Stats {
}
// SetForwarding enables or disables the packet forwarding between NICs.
+//
+// When forwarding becomes enabled, any host-only state on all NICs will be
+// cleaned up.
func (s *Stack) SetForwarding(enable bool) {
// TODO(igudger, bgeffon): Expose via /proc/sys/net/ipv4/ip_forward.
s.mu.Lock()
+ defer s.mu.Unlock()
+
+ // If forwarding status didn't change, do nothing further.
+ if s.forwarding == enable {
+ return
+ }
+
s.forwarding = enable
- s.mu.Unlock()
+
+ // If this stack does not support IPv6, do nothing further.
+ if _, ok := s.networkProtocols[header.IPv6ProtocolNumber]; !ok {
+ return
+ }
+
+ if enable {
+ for _, nic := range s.nics {
+ nic.becomeIPv6Router()
+ }
+ }
}
// Forwarding returns if the packet forwarding between NICs is enabled.
--
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