diff options
| -rw-r--r-- | pkg/tcpip/stack/ndp.go | 141 | ||||
| -rw-r--r-- | pkg/tcpip/stack/ndp_test.go | 209 |
2 files changed, 299 insertions, 51 deletions
diff --git a/pkg/tcpip/stack/ndp.go b/pkg/tcpip/stack/ndp.go index fbc0e3f55..15343acbc 100644 --- a/pkg/tcpip/stack/ndp.go +++ b/pkg/tcpip/stack/ndp.go @@ -145,6 +145,10 @@ const ( // minRegenAdvanceDuration is the minimum duration before the deprecation // of a temporary address when a new address will be generated. minRegenAdvanceDuration = time.Duration(0) + + // maxSLAACAddrLocalRegenAttempts is the maximum number of times to attempt + // SLAAC address regenerations in response to a NIC-local conflict. + maxSLAACAddrLocalRegenAttempts = 10 ) var ( @@ -565,11 +569,18 @@ type slaacPrefixState struct { // Nonzero only when the address is not preferred forever. preferredUntil time.Time - // The endpoint for the stable address generated for a SLAAC prefix. - // - // May only be nil when a SLAAC address is being (re-)generated. Otherwise, - // must not be nil as all SLAAC prefixes must have a stable address. - stableAddrRef *referencedNetworkEndpoint + // State associated with the stable address generated for the prefix. + stableAddr struct { + // The address's endpoint. + // + // May only be nil when the address is being (re-)generated. Otherwise, + // must not be nil as all SLAAC prefixes must have a stable address. + ref *referencedNetworkEndpoint + + // The number of times an address has been generated locally where the NIC + // already had the generated address. + localGenerationFailures uint8 + } // The temporary (short-lived) addresses generated for the SLAAC prefix. tempAddrs map[tcpip.Address]tempSLAACAddrState @@ -579,7 +590,7 @@ type slaacPrefixState struct { // in the generation and DAD process at any time. That is, no two addresses // will be generated at the same time for a given SLAAC prefix. - // The number of times an address has been generated. + // The number of times an address has been generated and added to the NIC. // // Addresses may be regenerated in reseponse to a DAD conflicts. generationAttempts uint8 @@ -1125,7 +1136,7 @@ func (ndp *ndpState) doSLAAC(prefix tcpip.Subnet, pl, vl time.Duration) { panic(fmt.Sprintf("ndp: must have a slaacPrefixes entry for the deprecated SLAAC prefix %s", prefix)) } - ndp.deprecateSLAACAddress(state.stableAddrRef) + ndp.deprecateSLAACAddress(state.stableAddr.ref) }), invalidationTimer: tcpip.NewCancellableTimer(&ndp.nic.mu, func() { state, ok := ndp.slaacPrefixes[prefix] @@ -1166,7 +1177,7 @@ func (ndp *ndpState) doSLAAC(prefix tcpip.Subnet, pl, vl time.Duration) { } // If the address is assigned (DAD resolved), generate a temporary address. - if state.stableAddrRef.getKind() == permanent { + if state.stableAddr.ref.getKind() == permanent { // Reset the generation attempts counter as we are starting the generation // of a new address for the SLAAC prefix. ndp.generateTempSLAACAddr(prefix, &state, true /* resetGenAttempts */) @@ -1179,11 +1190,6 @@ func (ndp *ndpState) doSLAAC(prefix tcpip.Subnet, pl, vl time.Duration) { // // The NIC that ndp belongs to MUST be locked. func (ndp *ndpState) addSLAACAddr(addr tcpip.AddressWithPrefix, configType networkEndpointConfigType, deprecated bool) *referencedNetworkEndpoint { - // If the nic already has this address, do nothing further. - if ndp.nic.hasPermanentAddrLocked(addr.Address) { - return nil - } - // Inform the integrator that we have a new SLAAC address. ndpDisp := ndp.nic.stack.ndpDisp if ndpDisp == nil { @@ -1216,7 +1222,7 @@ func (ndp *ndpState) addSLAACAddr(addr tcpip.AddressWithPrefix, configType netwo // // The NIC that ndp belongs to MUST be locked. func (ndp *ndpState) generateSLAACAddr(prefix tcpip.Subnet, state *slaacPrefixState) bool { - if r := state.stableAddrRef; r != nil { + if r := state.stableAddr.ref; r != nil { panic(fmt.Sprintf("ndp: SLAAC prefix %s already has a permenant address %s", prefix, r.addrWithPrefix())) } @@ -1226,42 +1232,62 @@ func (ndp *ndpState) generateSLAACAddr(prefix tcpip.Subnet, state *slaacPrefixSt return false } + var generatedAddr tcpip.AddressWithPrefix addrBytes := []byte(prefix.ID()) - if oIID := ndp.nic.stack.opaqueIIDOpts; oIID.NICNameFromID != nil { - addrBytes = header.AppendOpaqueInterfaceIdentifier( - addrBytes[:header.IIDOffsetInIPv6Address], - prefix, - oIID.NICNameFromID(ndp.nic.ID(), ndp.nic.name), - state.generationAttempts, - oIID.SecretKey, - ) - } else if state.generationAttempts == 0 { - // Only attempt to generate an interface-specific IID if we have a valid - // link address. - // - // TODO(b/141011931): Validate a LinkEndpoint's link address (provided by - // LinkEndpoint.LinkAddress) before reaching this point. - linkAddr := ndp.nic.linkEP.LinkAddress() - if !header.IsValidUnicastEthernetAddress(linkAddr) { + + for i := 0; ; i++ { + // If we were unable to generate an address after the maximum SLAAC address + // local regeneration attempts, do nothing further. + if i == maxSLAACAddrLocalRegenAttempts { return false } - // Generate an address within prefix from the modified EUI-64 of ndp's NIC's - // Ethernet MAC address. - header.EthernetAdddressToModifiedEUI64IntoBuf(linkAddr, addrBytes[header.IIDOffsetInIPv6Address:]) - } else { - // We have no way to regenerate an address when addresses are not generated - // with opaque IIDs. - return false - } + dadCounter := state.generationAttempts + state.stableAddr.localGenerationFailures + if oIID := ndp.nic.stack.opaqueIIDOpts; oIID.NICNameFromID != nil { + addrBytes = header.AppendOpaqueInterfaceIdentifier( + addrBytes[:header.IIDOffsetInIPv6Address], + prefix, + oIID.NICNameFromID(ndp.nic.ID(), ndp.nic.name), + dadCounter, + oIID.SecretKey, + ) + } else if dadCounter == 0 { + // Modified-EUI64 based IIDs have no way to resolve DAD conflicts, so if + // the DAD counter is non-zero, we cannot use this method. + // + // Only attempt to generate an interface-specific IID if we have a valid + // link address. + // + // TODO(b/141011931): Validate a LinkEndpoint's link address (provided by + // LinkEndpoint.LinkAddress) before reaching this point. + linkAddr := ndp.nic.linkEP.LinkAddress() + if !header.IsValidUnicastEthernetAddress(linkAddr) { + return false + } + + // Generate an address within prefix from the modified EUI-64 of ndp's + // NIC's Ethernet MAC address. + header.EthernetAdddressToModifiedEUI64IntoBuf(linkAddr, addrBytes[header.IIDOffsetInIPv6Address:]) + } else { + // We have no way to regenerate an address in response to an address + // conflict when addresses are not generated with opaque IIDs. + return false + } + + generatedAddr = tcpip.AddressWithPrefix{ + Address: tcpip.Address(addrBytes), + PrefixLen: validPrefixLenForAutoGen, + } - generatedAddr := tcpip.AddressWithPrefix{ - Address: tcpip.Address(addrBytes), - PrefixLen: validPrefixLenForAutoGen, + if !ndp.nic.hasPermanentAddrLocked(generatedAddr.Address) { + break + } + + state.stableAddr.localGenerationFailures++ } if ref := ndp.addSLAACAddr(generatedAddr, slaac, time.Since(state.preferredUntil) >= 0 /* deprecated */); ref != nil { - state.stableAddrRef = ref + state.stableAddr.ref = ref state.generationAttempts++ return true } @@ -1315,7 +1341,7 @@ func (ndp *ndpState) generateTempSLAACAddr(prefix tcpip.Subnet, prefixState *sla return false } - stableAddr := prefixState.stableAddrRef.ep.ID().LocalAddress + stableAddr := prefixState.stableAddr.ref.ep.ID().LocalAddress now := time.Now() // As per RFC 4941 section 3.3 step 4, the valid lifetime of a temporary @@ -1354,7 +1380,20 @@ func (ndp *ndpState) generateTempSLAACAddr(prefix tcpip.Subnet, prefixState *sla return false } - generatedAddr := header.GenerateTempIPv6SLAACAddr(ndp.temporaryIIDHistory[:], stableAddr) + // Attempt to generate a new address that is not already assigned to the NIC. + var generatedAddr tcpip.AddressWithPrefix + for i := 0; ; i++ { + // If we were unable to generate an address after the maximum SLAAC address + // local regeneration attempts, do nothing further. + if i == maxSLAACAddrLocalRegenAttempts { + return false + } + + generatedAddr = header.GenerateTempIPv6SLAACAddr(ndp.temporaryIIDHistory[:], stableAddr) + if !ndp.nic.hasPermanentAddrLocked(generatedAddr.Address) { + break + } + } // As per RFC RFC 4941 section 3.3 step 5, we MUST NOT create a temporary // address with a zero preferred lifetime. The checks above ensure this @@ -1450,9 +1489,9 @@ func (ndp *ndpState) refreshSLAACPrefixLifetimes(prefix tcpip.Subnet, prefixStat // If the preferred lifetime is zero, then the prefix should be deprecated. deprecated := pl == 0 if deprecated { - ndp.deprecateSLAACAddress(prefixState.stableAddrRef) + ndp.deprecateSLAACAddress(prefixState.stableAddr.ref) } else { - prefixState.stableAddrRef.deprecated = false + prefixState.stableAddr.ref.deprecated = false } // If prefix was preferred for some finite lifetime before, stop the @@ -1514,7 +1553,7 @@ func (ndp *ndpState) refreshSLAACPrefixLifetimes(prefix tcpip.Subnet, prefixStat // If DAD is not yet complete on the stable address, there is no need to do // work with temporary addresses. - if prefixState.stableAddrRef.getKind() != permanent { + if prefixState.stableAddr.ref.getKind() != permanent { return } @@ -1617,7 +1656,7 @@ func (ndp *ndpState) deprecateSLAACAddress(ref *referencedNetworkEndpoint) { // // The NIC that ndp belongs to MUST be locked. func (ndp *ndpState) invalidateSLAACPrefix(prefix tcpip.Subnet, state slaacPrefixState) { - if r := state.stableAddrRef; r != nil { + if r := state.stableAddr.ref; r != nil { // Since we are already invalidating the prefix, do not invalidate the // prefix when removing the address. if err := ndp.nic.removePermanentIPv6EndpointLocked(r, false /* allowSLAACInvalidation */); err != nil { @@ -1639,14 +1678,14 @@ func (ndp *ndpState) cleanupSLAACAddrResourcesAndNotify(addr tcpip.AddressWithPr prefix := addr.Subnet() state, ok := ndp.slaacPrefixes[prefix] - if !ok || state.stableAddrRef == nil || addr.Address != state.stableAddrRef.ep.ID().LocalAddress { + if !ok || state.stableAddr.ref == nil || addr.Address != state.stableAddr.ref.ep.ID().LocalAddress { return } if !invalidatePrefix { // If the prefix is not being invalidated, disassociate the address from the // prefix and do nothing further. - state.stableAddrRef = nil + state.stableAddr.ref = nil ndp.slaacPrefixes[prefix] = state return } @@ -1665,7 +1704,7 @@ func (ndp *ndpState) cleanupSLAACPrefixResources(prefix tcpip.Subnet, state slaa ndp.invalidateTempSLAACAddr(state.tempAddrs, tempAddr, tempAddrState) } - state.stableAddrRef = nil + state.stableAddr.ref = nil state.deprecationTimer.StopLocked() state.invalidationTimer.StopLocked() delete(ndp.slaacPrefixes, prefix) diff --git a/pkg/tcpip/stack/ndp_test.go b/pkg/tcpip/stack/ndp_test.go index 421df674f..67f012840 100644 --- a/pkg/tcpip/stack/ndp_test.go +++ b/pkg/tcpip/stack/ndp_test.go @@ -2521,6 +2521,215 @@ func TestAutoGenTempAddrRegenTimerUpdates(t *testing.T) { expectAutoGenAddrEventAsync(tempAddr3, newAddr, regenAfter+defaultAsyncEventTimeout) } +// TestMixedSLAACAddrConflictRegen tests SLAAC address regeneration in response +// to a mix of DAD conflicts and NIC-local conflicts. +func TestMixedSLAACAddrConflictRegen(t *testing.T) { + const ( + nicID = 1 + nicName = "nic" + lifetimeSeconds = 9999 + // From stack.maxSLAACAddrLocalRegenAttempts + maxSLAACAddrLocalRegenAttempts = 10 + // We use 2 more addreses than the maximum local regeneration attempts + // because we want to also trigger regeneration in response to a DAD + // conflicts for this test. + maxAddrs = maxSLAACAddrLocalRegenAttempts + 2 + dupAddrTransmits = 1 + retransmitTimer = time.Second + ) + + var tempIIDHistoryWithModifiedEUI64 [header.IIDSize]byte + header.InitialTempIID(tempIIDHistoryWithModifiedEUI64[:], nil, nicID) + + var tempIIDHistoryWithOpaqueIID [header.IIDSize]byte + header.InitialTempIID(tempIIDHistoryWithOpaqueIID[:], nil, nicID) + + prefix, subnet, stableAddrWithModifiedEUI64 := prefixSubnetAddr(0, linkAddr1) + var stableAddrsWithOpaqueIID [maxAddrs]tcpip.AddressWithPrefix + var tempAddrsWithOpaqueIID [maxAddrs]tcpip.AddressWithPrefix + var tempAddrsWithModifiedEUI64 [maxAddrs]tcpip.AddressWithPrefix + addrBytes := []byte(subnet.ID()) + for i := 0; i < maxAddrs; i++ { + stableAddrsWithOpaqueIID[i] = tcpip.AddressWithPrefix{ + Address: tcpip.Address(header.AppendOpaqueInterfaceIdentifier(addrBytes[:header.IIDOffsetInIPv6Address], subnet, nicName, uint8(i), nil)), + PrefixLen: header.IIDOffsetInIPv6Address * 8, + } + // When generating temporary addresses, the resolved stable address for the + // SLAAC prefix will be the first address stable address generated for the + // prefix as we will not simulate address conflicts for the stable addresses + // in tests involving temporary addresses. Address conflicts for stable + // addresses will be done in their own tests. + tempAddrsWithOpaqueIID[i] = header.GenerateTempIPv6SLAACAddr(tempIIDHistoryWithOpaqueIID[:], stableAddrsWithOpaqueIID[0].Address) + tempAddrsWithModifiedEUI64[i] = header.GenerateTempIPv6SLAACAddr(tempIIDHistoryWithModifiedEUI64[:], stableAddrWithModifiedEUI64.Address) + } + + tests := []struct { + name string + addrs []tcpip.AddressWithPrefix + tempAddrs bool + initialExpect tcpip.AddressWithPrefix + nicNameFromID func(tcpip.NICID, string) string + }{ + { + name: "Stable addresses with opaque IIDs", + addrs: stableAddrsWithOpaqueIID[:], + nicNameFromID: func(tcpip.NICID, string) string { + return nicName + }, + }, + { + name: "Temporary addresses with opaque IIDs", + addrs: tempAddrsWithOpaqueIID[:], + tempAddrs: true, + initialExpect: stableAddrsWithOpaqueIID[0], + nicNameFromID: func(tcpip.NICID, string) string { + return nicName + }, + }, + { + name: "Temporary addresses with modified EUI64", + addrs: tempAddrsWithModifiedEUI64[:], + tempAddrs: true, + initialExpect: stableAddrWithModifiedEUI64, + }, + } + + for _, test := range tests { + test := test + + t.Run(test.name, func(t *testing.T) { + t.Parallel() + + ndpDisp := ndpDispatcher{ + autoGenAddrC: make(chan ndpAutoGenAddrEvent, 2), + } + e := channel.New(0, 1280, linkAddr1) + ndpConfigs := stack.NDPConfigurations{ + HandleRAs: true, + AutoGenGlobalAddresses: true, + AutoGenTempGlobalAddresses: test.tempAddrs, + AutoGenAddressConflictRetries: 1, + } + s := stack.New(stack.Options{ + NetworkProtocols: []stack.NetworkProtocol{ipv6.NewProtocol()}, + TransportProtocols: []stack.TransportProtocol{udp.NewProtocol()}, + NDPConfigs: ndpConfigs, + NDPDisp: &ndpDisp, + OpaqueIIDOpts: stack.OpaqueInterfaceIdentifierOptions{ + NICNameFromID: test.nicNameFromID, + }, + }) + + s.SetRouteTable([]tcpip.Route{{ + Destination: header.IPv6EmptySubnet, + Gateway: llAddr2, + NIC: nicID, + }}) + + if err := s.CreateNIC(nicID, e); err != nil { + t.Fatalf("CreateNIC(%d, _) = %s", nicID, err) + } + + for j := 0; j < len(test.addrs)-1; j++ { + // The NIC will not attempt to generate an address in response to a + // NIC-local conflict after some maximum number of attempts. We skip + // creating a conflict for the address that would be generated as part + // of the last attempt so we can simulate a DAD conflict for this + // address and restart the NIC-local generation process. + if j == maxSLAACAddrLocalRegenAttempts-1 { + continue + } + + if err := s.AddAddress(nicID, ipv6.ProtocolNumber, test.addrs[j].Address); err != nil { + t.Fatalf("s.AddAddress(%d, %d, %s): %s", nicID, ipv6.ProtocolNumber, test.addrs[j].Address, err) + } + } + + expectAutoGenAddrEvent := func(addr tcpip.AddressWithPrefix, eventType ndpAutoGenAddrEventType) { + t.Helper() + + select { + case e := <-ndpDisp.autoGenAddrC: + if diff := checkAutoGenAddrEvent(e, addr, eventType); diff != "" { + t.Errorf("auto-gen addr event mismatch (-want +got):\n%s", diff) + } + default: + t.Fatal("expected addr auto gen event") + } + } + + expectAutoGenAddrAsyncEvent := func(addr tcpip.AddressWithPrefix, eventType ndpAutoGenAddrEventType) { + t.Helper() + + select { + case e := <-ndpDisp.autoGenAddrC: + if diff := checkAutoGenAddrEvent(e, addr, eventType); diff != "" { + t.Errorf("auto-gen addr event mismatch (-want +got):\n%s", diff) + } + case <-time.After(defaultAsyncEventTimeout): + t.Fatal("timed out waiting for addr auto gen event") + } + } + + expectDADEventAsync := func(addr tcpip.Address) { + t.Helper() + + select { + case e := <-ndpDisp.dadC: + if diff := checkDADEvent(e, nicID, addr, true, nil); diff != "" { + t.Errorf("dad event mismatch (-want +got):\n%s", diff) + } + case <-time.After(dupAddrTransmits*retransmitTimer + defaultAsyncEventTimeout): + t.Fatal("timed out waiting for DAD event") + } + } + + // Enable DAD. + ndpDisp.dadC = make(chan ndpDADEvent, 2) + ndpConfigs.DupAddrDetectTransmits = dupAddrTransmits + ndpConfigs.RetransmitTimer = retransmitTimer + if err := s.SetNDPConfigurations(nicID, ndpConfigs); err != nil { + t.Fatalf("s.SetNDPConfigurations(%d, _): %s", nicID, err) + } + + // Do SLAAC for prefix. + e.InjectInbound(header.IPv6ProtocolNumber, raBufWithPI(llAddr2, 0, prefix, true, true, lifetimeSeconds, lifetimeSeconds)) + if test.initialExpect != (tcpip.AddressWithPrefix{}) { + expectAutoGenAddrEvent(test.initialExpect, newAddr) + expectDADEventAsync(test.initialExpect.Address) + } + + // The last local generation attempt should succeed, but we introduce a + // DAD failure to restart the local generation process. + addr := test.addrs[maxSLAACAddrLocalRegenAttempts-1] + expectAutoGenAddrAsyncEvent(addr, newAddr) + if err := s.DupTentativeAddrDetected(nicID, addr.Address); err != nil { + t.Fatalf("s.DupTentativeAddrDetected(%d, %s): %s", nicID, addr.Address, err) + } + select { + case e := <-ndpDisp.dadC: + if diff := checkDADEvent(e, nicID, addr.Address, false, nil); diff != "" { + t.Errorf("dad event mismatch (-want +got):\n%s", diff) + } + default: + t.Fatal("expected DAD event") + } + expectAutoGenAddrEvent(addr, invalidatedAddr) + + // The last address generated should resolve DAD. + addr = test.addrs[len(test.addrs)-1] + expectAutoGenAddrAsyncEvent(addr, newAddr) + expectDADEventAsync(addr.Address) + + select { + case e := <-ndpDisp.autoGenAddrC: + t.Fatalf("unexpected auto gen addr event = %+v", e) + default: + } + }) + } +} + // stackAndNdpDispatcherWithDefaultRoute returns an ndpDispatcher, // channel.Endpoint and stack.Stack. // |