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authorgVisor bot <gvisor-bot@google.com>2020-01-16 01:23:10 +0000
committergVisor bot <gvisor-bot@google.com>2020-01-16 01:23:10 +0000
commit8051a5e7c093b87ce9ccf650961768711958be03 (patch)
treeb3196839fa6455b232567f7ce492bc3b82935d44 /pkg/tcpip/stack
parent6a9b381a93e88b8ecc681cc0f92a810dbcc58e7d (diff)
parent815df2959a76e4a19f5882e40402b9bbca9e70be (diff)
Merge release-20200115.0-3-g815df29 (automated)
Diffstat (limited to 'pkg/tcpip/stack')
-rwxr-xr-xpkg/tcpip/stack/ndp.go175
-rw-r--r--pkg/tcpip/stack/nic.go73
-rw-r--r--pkg/tcpip/stack/stack.go8
3 files changed, 211 insertions, 45 deletions
diff --git a/pkg/tcpip/stack/ndp.go b/pkg/tcpip/stack/ndp.go
index a9dd322db..acefc356a 100755
--- a/pkg/tcpip/stack/ndp.go
+++ b/pkg/tcpip/stack/ndp.go
@@ -17,6 +17,7 @@ package stack
import (
"fmt"
"log"
+ "math/rand"
"time"
"gvisor.dev/gvisor/pkg/tcpip"
@@ -38,24 +39,36 @@ 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 +87,31 @@ 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 +263,24 @@ 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 +311,15 @@ 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 +328,24 @@ 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 +366,10 @@ 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
@@ -501,10 +555,12 @@ func (ndp *ndpState) doDuplicateAddressDetection(addr tcpip.Address, remaining u
// 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))
}
+ snmcRef.incRef()
// 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)
+ defer r.Release()
hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.ICMPv6NeighborSolicitMinimumSize)
pkt := header.ICMPv6(hdr.Prepend(header.ICMPv6NeighborSolicitMinimumSize))
@@ -1132,3 +1188,84 @@ 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, true)
+ 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
+}
diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go
index 071221d5a..1089fdf35 100644
--- a/pkg/tcpip/stack/nic.go
+++ b/pkg/tcpip/stack/nic.go
@@ -177,49 +177,72 @@ func (n *NIC) enable() *tcpip.Error {
}
// Do not auto-generate an IPv6 link-local address for loopback devices.
- if !n.stack.autoGenIPv6LinkLocal || n.isLoopback() {
- return nil
- }
+ if n.stack.autoGenIPv6LinkLocal && !n.isLoopback() {
+ var addr tcpip.Address
+ if oIID := n.stack.opaqueIIDOpts; oIID.NICNameFromID != nil {
+ addr = header.LinkLocalAddrWithOpaqueIID(oIID.NICNameFromID(n.ID(), n.name), 0, oIID.SecretKey)
+ } else {
+ l2addr := n.linkEP.LinkAddress()
- var addr tcpip.Address
- if oIID := n.stack.opaqueIIDOpts; oIID.NICNameFromID != nil {
- addr = header.LinkLocalAddrWithOpaqueIID(oIID.NICNameFromID(n.ID(), n.name), 0, oIID.SecretKey)
- } else {
- l2addr := n.linkEP.LinkAddress()
+ // Only attempt to generate the link-local address if we have a valid MAC
+ // address.
+ //
+ // TODO(b/141011931): Validate a LinkEndpoint's link address (provided by
+ // LinkEndpoint.LinkAddress) before reaching this point.
+ if !header.IsValidUnicastEthernetAddress(l2addr) {
+ return nil
+ }
- // Only attempt to generate the link-local address if we have a valid MAC
- // address.
- //
- // TODO(b/141011931): Validate a LinkEndpoint's link address (provided by
- // LinkEndpoint.LinkAddress) before reaching this point.
- if !header.IsValidUnicastEthernetAddress(l2addr) {
- return nil
+ addr = header.LinkLocalAddr(l2addr)
}
- addr = header.LinkLocalAddr(l2addr)
+ if _, err := n.addPermanentAddressLocked(tcpip.ProtocolAddress{
+ Protocol: header.IPv6ProtocolNumber,
+ AddressWithPrefix: tcpip.AddressWithPrefix{
+ Address: addr,
+ PrefixLen: header.IPv6LinkLocalPrefix.PrefixLen,
+ },
+ }, CanBePrimaryEndpoint); err != nil {
+ return err
+ }
}
- _, err := n.addPermanentAddressLocked(tcpip.ProtocolAddress{
- Protocol: header.IPv6ProtocolNumber,
- AddressWithPrefix: tcpip.AddressWithPrefix{
- Address: addr,
- PrefixLen: header.IPv6LinkLocalPrefix.PrefixLen,
- },
- }, CanBePrimaryEndpoint)
+ // If we are operating as a router, then do not solicit routers since we
+ // won't process the RAs anyways.
+ //
+ // Routers do not process Router Advertisements (RA) the same way a host
+ // does. That is, routers do not learn from RAs (e.g. on-link prefixes
+ // and default routers). Therefore, soliciting RAs from other routers on
+ // a link is unnecessary for routers.
+ if !n.stack.forwarding {
+ n.ndp.startSolicitingRouters()
+ }
- return err
+ return nil
}
// 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.
+// be cleaned up/invalidated and NDP router solicitations will be stopped.
func (n *NIC) becomeIPv6Router() {
n.mu.Lock()
defer n.mu.Unlock()
n.ndp.cleanupHostOnlyState()
+ n.ndp.stopSolicitingRouters()
+}
+
+// becomeIPv6Host transitions n into an IPv6 host.
+//
+// When transitioning into an IPv6 host, NDP router solicitations will be
+// started.
+func (n *NIC) becomeIPv6Host() {
+ n.mu.Lock()
+ defer n.mu.Unlock()
+
+ n.ndp.startSolicitingRouters()
}
// attachLinkEndpoint attaches the NIC to the endpoint, which will enable it
diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go
index 386eb6eec..fc56a6d79 100644
--- a/pkg/tcpip/stack/stack.go
+++ b/pkg/tcpip/stack/stack.go
@@ -750,7 +750,9 @@ 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.
+// cleaned up and if IPv6 is enabled, NDP Router Solicitations will be started.
+// When forwarding becomes disabled and if IPv6 is enabled, NDP Router
+// Solicitations will be stopped.
func (s *Stack) SetForwarding(enable bool) {
// TODO(igudger, bgeffon): Expose via /proc/sys/net/ipv4/ip_forward.
s.mu.Lock()
@@ -772,6 +774,10 @@ func (s *Stack) SetForwarding(enable bool) {
for _, nic := range s.nics {
nic.becomeIPv6Router()
}
+ } else {
+ for _, nic := range s.nics {
+ nic.becomeIPv6Host()
+ }
}
}