diff options
Diffstat (limited to 'pkg/tcpip/stack/ndp.go')
| -rw-r--r-- | pkg/tcpip/stack/ndp.go | 371 |
1 files changed, 244 insertions, 127 deletions
diff --git a/pkg/tcpip/stack/ndp.go b/pkg/tcpip/stack/ndp.go index a9dd322db..d983ac390 100644 --- a/pkg/tcpip/stack/ndp.go +++ b/pkg/tcpip/stack/ndp.go @@ -15,8 +15,8 @@ package stack import ( - "fmt" "log" + "math/rand" "time" "gvisor.dev/gvisor/pkg/tcpip" @@ -38,24 +38,36 @@ const ( // Default = 1s (from RFC 4861 section 10). defaultRetransmitTimer = time.Second + // defaultMaxRtrSolicitations is the default number of Router + // Solicitation messages to send when a NIC becomes enabled. + // + // Default = 3 (from RFC 4861 section 10). + defaultMaxRtrSolicitations = 3 + + // defaultRtrSolicitationInterval is the default amount of time between + // sending Router Solicitation messages. + // + // Default = 4s (from 4861 section 10). + defaultRtrSolicitationInterval = 4 * time.Second + + // defaultMaxRtrSolicitationDelay is the default maximum amount of time + // to wait before sending the first Router Solicitation message. + // + // Default = 1s (from 4861 section 10). + defaultMaxRtrSolicitationDelay = time.Second + // defaultHandleRAs is the default configuration for whether or not to // handle incoming Router Advertisements as a host. - // - // Default = true. defaultHandleRAs = true // defaultDiscoverDefaultRouters is the default configuration for // whether or not to discover default routers from incoming Router // Advertisements, as a host. - // - // Default = true. defaultDiscoverDefaultRouters = true // defaultDiscoverOnLinkPrefixes is the default configuration for // whether or not to discover on-link prefixes from incoming Router // Advertisements' Prefix Information option, as a host. - // - // Default = true. defaultDiscoverOnLinkPrefixes = true // defaultAutoGenGlobalAddresses is the default configuration for @@ -74,26 +86,31 @@ const ( // value of 0 means unspecified, so the smallest valid value is 1. // Note, the unit of the RetransmitTimer field in the Router // Advertisement is milliseconds. - // - // Min = 1ms. minimumRetransmitTimer = time.Millisecond + // minimumRtrSolicitationInterval is the minimum amount of time to wait + // between sending Router Solicitation messages. This limit is imposed + // to make sure that Router Solicitation messages are not sent all at + // once, defeating the purpose of sending the initial few messages. + minimumRtrSolicitationInterval = 500 * time.Millisecond + + // minimumMaxRtrSolicitationDelay is the minimum amount of time to wait + // before sending the first Router Solicitation message. It is 0 because + // we cannot have a negative delay. + minimumMaxRtrSolicitationDelay = 0 + // MaxDiscoveredDefaultRouters is the maximum number of discovered // default routers. The stack should stop discovering new routers after // discovering MaxDiscoveredDefaultRouters routers. // // This value MUST be at minimum 2 as per RFC 4861 section 6.3.4, and // SHOULD be more. - // - // Max = 10. MaxDiscoveredDefaultRouters = 10 // MaxDiscoveredOnLinkPrefixes is the maximum number of discovered // on-link prefixes. The stack should stop discovering new on-link // prefixes after discovering MaxDiscoveredOnLinkPrefixes on-link // prefixes. - // - // Max = 10. MaxDiscoveredOnLinkPrefixes = 10 // validPrefixLenForAutoGen is the expected prefix length that an @@ -245,9 +262,24 @@ type NDPConfigurations struct { // The amount of time to wait between sending Neighbor solicitation // messages. // - // Must be greater than 0.5s. + // Must be greater than or equal to 1ms. RetransmitTimer time.Duration + // The number of Router Solicitation messages to send when the NIC + // becomes enabled. + MaxRtrSolicitations uint8 + + // The amount of time between transmitting Router Solicitation messages. + // + // Must be greater than or equal to 0.5s. + RtrSolicitationInterval time.Duration + + // The maximum amount of time before transmitting the first Router + // Solicitation message. + // + // Must be greater than or equal to 0s. + MaxRtrSolicitationDelay time.Duration + // HandleRAs determines whether or not Router Advertisements will be // processed. HandleRAs bool @@ -278,12 +310,15 @@ type NDPConfigurations struct { // default values. func DefaultNDPConfigurations() NDPConfigurations { return NDPConfigurations{ - DupAddrDetectTransmits: defaultDupAddrDetectTransmits, - RetransmitTimer: defaultRetransmitTimer, - HandleRAs: defaultHandleRAs, - DiscoverDefaultRouters: defaultDiscoverDefaultRouters, - DiscoverOnLinkPrefixes: defaultDiscoverOnLinkPrefixes, - AutoGenGlobalAddresses: defaultAutoGenGlobalAddresses, + DupAddrDetectTransmits: defaultDupAddrDetectTransmits, + RetransmitTimer: defaultRetransmitTimer, + MaxRtrSolicitations: defaultMaxRtrSolicitations, + RtrSolicitationInterval: defaultRtrSolicitationInterval, + MaxRtrSolicitationDelay: defaultMaxRtrSolicitationDelay, + HandleRAs: defaultHandleRAs, + DiscoverDefaultRouters: defaultDiscoverDefaultRouters, + DiscoverOnLinkPrefixes: defaultDiscoverOnLinkPrefixes, + AutoGenGlobalAddresses: defaultAutoGenGlobalAddresses, } } @@ -292,10 +327,24 @@ func DefaultNDPConfigurations() NDPConfigurations { // // If RetransmitTimer is less than minimumRetransmitTimer, then a value of // defaultRetransmitTimer will be used. +// +// If RtrSolicitationInterval is less than minimumRtrSolicitationInterval, then +// a value of defaultRtrSolicitationInterval will be used. +// +// If MaxRtrSolicitationDelay is less than minimumMaxRtrSolicitationDelay, then +// a value of defaultMaxRtrSolicitationDelay will be used. func (c *NDPConfigurations) validate() { if c.RetransmitTimer < minimumRetransmitTimer { c.RetransmitTimer = defaultRetransmitTimer } + + if c.RtrSolicitationInterval < minimumRtrSolicitationInterval { + c.RtrSolicitationInterval = defaultRtrSolicitationInterval + } + + if c.MaxRtrSolicitationDelay < minimumMaxRtrSolicitationDelay { + c.MaxRtrSolicitationDelay = defaultMaxRtrSolicitationDelay + } } // ndpState is the per-interface NDP state. @@ -316,6 +365,10 @@ type ndpState struct { // Information option. onLinkPrefixes map[tcpip.Subnet]onLinkPrefixState + // The timer used to send the next router solicitation message. + // If routers are being solicited, rtrSolicitTimer MUST NOT be nil. + rtrSolicitTimer *time.Timer + // The addresses generated by SLAAC. autoGenAddresses map[tcpip.Address]autoGenAddressState @@ -375,87 +428,93 @@ func (ndp *ndpState) startDuplicateAddressDetection(addr tcpip.Address, ref *ref return tcpip.ErrAddressFamilyNotSupported } - // Should not attempt to perform DAD on an address that is currently in - // the DAD process. + if ref.getKind() != permanentTentative { + // The endpoint should be marked as tentative since we are starting DAD. + log.Fatalf("ndpdad: addr %s is not tentative on NIC(%d)", addr, ndp.nic.ID()) + } + + // Should not attempt to perform DAD on an address that is currently in the + // DAD process. if _, ok := ndp.dad[addr]; ok { - // Should never happen because we should only ever call this - // function for newly created addresses. If we attemped to - // "add" an address that already existed, we would returned an - // error since we attempted to add a duplicate address, or its - // reference count would have been increased without doing the - // work that would have been done for an address that was brand - // new. See NIC.addPermanentAddressLocked. - panic(fmt.Sprintf("ndpdad: already performing DAD for addr %s on NIC(%d)", addr, ndp.nic.ID())) + // Should never happen because we should only ever call this function for + // newly created addresses. If we attemped to "add" an address that already + // existed, we would get an error since we attempted to add a duplicate + // address, or its reference count would have been increased without doing + // the work that would have been done for an address that was brand new. + // See NIC.addAddressLocked. + log.Fatalf("ndpdad: already performing DAD for addr %s on NIC(%d)", addr, ndp.nic.ID()) } remaining := ndp.configs.DupAddrDetectTransmits - - { - done, err := ndp.doDuplicateAddressDetection(addr, remaining, ref) - if err != nil { - return err - } - if done { - return nil - } + if remaining == 0 { + ref.setKind(permanent) + return nil } - remaining-- - var done bool var timer *time.Timer - timer = time.AfterFunc(ndp.configs.RetransmitTimer, func() { - var d bool - var err *tcpip.Error - - // doDadIteration does a single iteration of the DAD loop. - // - // Returns true if the integrator needs to be informed of DAD - // completing. - doDadIteration := func() bool { - ndp.nic.mu.Lock() - defer ndp.nic.mu.Unlock() - - if done { - // If we reach this point, it means that the DAD - // timer fired after another goroutine already - // obtained the NIC lock and stopped DAD before - // this function obtained the NIC lock. Simply - // return here and do nothing further. - return false - } + // We initially start a timer to fire immediately because some of the DAD work + // cannot be done while holding the NIC's lock. This is effectively the same + // as starting a goroutine but we use a timer that fires immediately so we can + // reset it for the next DAD iteration. + timer = time.AfterFunc(0, func() { + ndp.nic.mu.RLock() + if done { + // If we reach this point, it means that the DAD timer fired after + // another goroutine already obtained the NIC lock and stopped DAD + // before this function obtained the NIC lock. Simply return here and do + // nothing further. + ndp.nic.mu.RUnlock() + return + } - ref, ok := ndp.nic.endpoints[NetworkEndpointID{addr}] - if !ok { - // This should never happen. - // We should have an endpoint for addr since we - // are still performing DAD on it. If the - // endpoint does not exist, but we are doing DAD - // on it, then we started DAD at some point, but - // forgot to stop it when the endpoint was - // deleted. - panic(fmt.Sprintf("ndpdad: unrecognized addr %s for NIC(%d)", addr, ndp.nic.ID())) - } + if ref.getKind() != permanentTentative { + // The endpoint should still be marked as tentative since we are still + // performing DAD on it. + log.Fatalf("ndpdad: addr %s is no longer tentative on NIC(%d)", addr, ndp.nic.ID()) + } - d, err = ndp.doDuplicateAddressDetection(addr, remaining, ref) - if err != nil || d { - delete(ndp.dad, addr) + dadDone := remaining == 0 + ndp.nic.mu.RUnlock() - if err != nil { - log.Printf("ndpdad: Error occured during DAD iteration for addr (%s) on NIC(%d); err = %s", addr, ndp.nic.ID(), err) - } + var err *tcpip.Error + if !dadDone { + err = ndp.sendDADPacket(addr) + } - // Let the integrator know DAD has completed. - return true - } + ndp.nic.mu.Lock() + if done { + // If we reach this point, it means that DAD was stopped after we released + // the NIC's read lock and before we obtained the write lock. + ndp.nic.mu.Unlock() + return + } + if dadDone { + // DAD has resolved. + ref.setKind(permanent) + } else if err == nil { + // DAD is not done and we had no errors when sending the last NDP NS, + // schedule the next DAD timer. remaining-- timer.Reset(ndp.nic.stack.ndpConfigs.RetransmitTimer) - return false + + ndp.nic.mu.Unlock() + return } - if doDadIteration() && ndp.nic.stack.ndpDisp != nil { - ndp.nic.stack.ndpDisp.OnDuplicateAddressDetectionStatus(ndp.nic.ID(), addr, d, err) + // At this point we know that either DAD is done or we hit an error sending + // the last NDP NS. Either way, clean up addr's DAD state and let the + // integrator know DAD has completed. + delete(ndp.dad, addr) + ndp.nic.mu.Unlock() + + if err != nil { + log.Printf("ndpdad: error occured during DAD iteration for addr (%s) on NIC(%d); err = %s", addr, ndp.nic.ID(), err) + } + + if ndpDisp := ndp.nic.stack.ndpDisp; ndpDisp != nil { + ndpDisp.OnDuplicateAddressDetectionStatus(ndp.nic.ID(), addr, dadDone, err) } }) @@ -467,44 +526,17 @@ func (ndp *ndpState) startDuplicateAddressDetection(addr tcpip.Address, ref *ref return nil } -// doDuplicateAddressDetection is called on every iteration of the timer, and -// when DAD starts. -// -// It handles resolving the address (if there are no more NS to send), or -// sending the next NS if there are more NS to send. +// sendDADPacket sends a NS message to see if any nodes on ndp's NIC's link owns +// addr. // -// This function must only be called by IPv6 addresses that are currently -// tentative. -// -// The NIC that ndp belongs to (n) MUST be locked. -// -// Returns true if DAD has resolved; false if DAD is still ongoing. -func (ndp *ndpState) doDuplicateAddressDetection(addr tcpip.Address, remaining uint8, ref *referencedNetworkEndpoint) (bool, *tcpip.Error) { - if ref.getKind() != permanentTentative { - // The endpoint should still be marked as tentative - // since we are still performing DAD on it. - panic(fmt.Sprintf("ndpdad: addr %s is not tentative on NIC(%d)", addr, ndp.nic.ID())) - } - - if remaining == 0 { - // DAD has resolved. - ref.setKind(permanent) - return true, nil - } - - // Send a new NS. +// addr must be a tentative IPv6 address on ndp's NIC. +func (ndp *ndpState) sendDADPacket(addr tcpip.Address) *tcpip.Error { snmc := header.SolicitedNodeAddr(addr) - snmcRef, ok := ndp.nic.endpoints[NetworkEndpointID{snmc}] - if !ok { - // This should never happen as if we have the - // address, we should have the solicited-node - // address. - panic(fmt.Sprintf("ndpdad: NIC(%d) is not in the solicited-node multicast group (%s) but it has addr %s", ndp.nic.ID(), snmc, addr)) - } - // Use the unspecified address as the source address when performing - // DAD. - r := makeRoute(header.IPv6ProtocolNumber, header.IPv6Any, snmc, ndp.nic.linkEP.LinkAddress(), snmcRef, false, false) + // Use the unspecified address as the source address when performing DAD. + ref := ndp.nic.getRefOrCreateTemp(header.IPv6ProtocolNumber, header.IPv6Any, NeverPrimaryEndpoint, forceSpoofing) + r := makeRoute(header.IPv6ProtocolNumber, header.IPv6Any, snmc, ndp.nic.linkEP.LinkAddress(), ref, false, false) + defer r.Release() hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.ICMPv6NeighborSolicitMinimumSize) pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6NeighborSolicitMinimumSize)) @@ -514,15 +546,19 @@ func (ndp *ndpState) doDuplicateAddressDetection(addr tcpip.Address, remaining u pkt.SetChecksum(header.ICMPv6Checksum(pkt, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{})) sent := r.Stats().ICMP.V6PacketsSent - if err := r.WritePacket(nil, NetworkHeaderParams{Protocol: header.ICMPv6ProtocolNumber, TTL: header.NDPHopLimit, TOS: DefaultTOS}, tcpip.PacketBuffer{ - Header: hdr, - }); err != nil { + if err := r.WritePacket(nil, + NetworkHeaderParams{ + Protocol: header.ICMPv6ProtocolNumber, + TTL: header.NDPHopLimit, + TOS: DefaultTOS, + }, tcpip.PacketBuffer{Header: hdr}, + ); err != nil { sent.Dropped.Increment() - return false, err + return err } sent.NeighborSolicit.Increment() - return false, nil + return nil } // stopDuplicateAddressDetection ends a running Duplicate Address Detection @@ -1108,7 +1144,7 @@ func (ndp *ndpState) cleanupAutoGenAddrResourcesAndNotify(addr tcpip.Address) bo // // The NIC that ndp belongs to MUST be locked. func (ndp *ndpState) cleanupHostOnlyState() { - for addr, _ := range ndp.autoGenAddresses { + for addr := range ndp.autoGenAddresses { ndp.invalidateAutoGenAddress(addr) } @@ -1116,7 +1152,7 @@ func (ndp *ndpState) cleanupHostOnlyState() { log.Fatalf("ndp: still have auto-generated addresses after cleaning up, found = %d", got) } - for prefix, _ := range ndp.onLinkPrefixes { + for prefix := range ndp.onLinkPrefixes { ndp.invalidateOnLinkPrefix(prefix) } @@ -1124,7 +1160,7 @@ func (ndp *ndpState) cleanupHostOnlyState() { log.Fatalf("ndp: still have discovered on-link prefixes after cleaning up, found = %d", got) } - for router, _ := range ndp.defaultRouters { + for router := range ndp.defaultRouters { ndp.invalidateDefaultRouter(router) } @@ -1132,3 +1168,84 @@ func (ndp *ndpState) cleanupHostOnlyState() { log.Fatalf("ndp: still have discovered default routers after cleaning up, found = %d", got) } } + +// startSolicitingRouters starts soliciting routers, as per RFC 4861 section +// 6.3.7. If routers are already being solicited, this function does nothing. +// +// The NIC ndp belongs to MUST be locked. +func (ndp *ndpState) startSolicitingRouters() { + if ndp.rtrSolicitTimer != nil { + // We are already soliciting routers. + return + } + + remaining := ndp.configs.MaxRtrSolicitations + if remaining == 0 { + return + } + + // Calculate the random delay before sending our first RS, as per RFC + // 4861 section 6.3.7. + var delay time.Duration + if ndp.configs.MaxRtrSolicitationDelay > 0 { + delay = time.Duration(rand.Int63n(int64(ndp.configs.MaxRtrSolicitationDelay))) + } + + ndp.rtrSolicitTimer = time.AfterFunc(delay, func() { + // Send an RS message with the unspecified source address. + ref := ndp.nic.getRefOrCreateTemp(header.IPv6ProtocolNumber, header.IPv6Any, NeverPrimaryEndpoint, forceSpoofing) + r := makeRoute(header.IPv6ProtocolNumber, header.IPv6Any, header.IPv6AllRoutersMulticastAddress, ndp.nic.linkEP.LinkAddress(), ref, false, false) + defer r.Release() + + payloadSize := header.ICMPv6HeaderSize + header.NDPRSMinimumSize + hdr := buffer.NewPrependable(header.IPv6MinimumSize + payloadSize) + pkt := header.ICMPv6(hdr.Prepend(payloadSize)) + pkt.SetType(header.ICMPv6RouterSolicit) + pkt.SetChecksum(header.ICMPv6Checksum(pkt, r.LocalAddress, r.RemoteAddress, buffer.VectorisedView{})) + + sent := r.Stats().ICMP.V6PacketsSent + if err := r.WritePacket(nil, + NetworkHeaderParams{ + Protocol: header.ICMPv6ProtocolNumber, + TTL: header.NDPHopLimit, + TOS: DefaultTOS, + }, tcpip.PacketBuffer{Header: hdr}, + ); err != nil { + sent.Dropped.Increment() + log.Printf("startSolicitingRouters: error writing NDP router solicit message on NIC(%d); err = %s", ndp.nic.ID(), err) + // Don't send any more messages if we had an error. + remaining = 0 + } else { + sent.RouterSolicit.Increment() + remaining-- + } + + ndp.nic.mu.Lock() + defer ndp.nic.mu.Unlock() + if remaining == 0 { + ndp.rtrSolicitTimer = nil + } else if ndp.rtrSolicitTimer != nil { + // Note, we need to explicitly check to make sure that + // the timer field is not nil because if it was nil but + // we still reached this point, then we know the NIC + // was requested to stop soliciting routers so we don't + // need to send the next Router Solicitation message. + ndp.rtrSolicitTimer.Reset(ndp.configs.RtrSolicitationInterval) + } + }) + +} + +// stopSolicitingRouters stops soliciting routers. If routers are not currently +// being solicited, this function does nothing. +// +// The NIC ndp belongs to MUST be locked. +func (ndp *ndpState) stopSolicitingRouters() { + if ndp.rtrSolicitTimer == nil { + // Nothing to do. + return + } + + ndp.rtrSolicitTimer.Stop() + ndp.rtrSolicitTimer = nil +} |