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Diffstat (limited to 'pkg/tcpip/stack/nic.go')
| -rw-r--r-- | pkg/tcpip/stack/nic.go | 1743 |
1 files changed, 1743 insertions, 0 deletions
diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go new file mode 100644 index 000000000..7b80534e6 --- /dev/null +++ b/pkg/tcpip/stack/nic.go @@ -0,0 +1,1743 @@ +// Copyright 2018 The gVisor Authors. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package stack + +import ( + "fmt" + "reflect" + "sort" + "strings" + "sync/atomic" + + "gvisor.dev/gvisor/pkg/sync" + "gvisor.dev/gvisor/pkg/tcpip" + "gvisor.dev/gvisor/pkg/tcpip/buffer" + "gvisor.dev/gvisor/pkg/tcpip/header" +) + +var ipv4BroadcastAddr = tcpip.ProtocolAddress{ + Protocol: header.IPv4ProtocolNumber, + AddressWithPrefix: tcpip.AddressWithPrefix{ + Address: header.IPv4Broadcast, + PrefixLen: 8 * header.IPv4AddressSize, + }, +} + +// NIC represents a "network interface card" to which the networking stack is +// attached. +type NIC struct { + stack *Stack + id tcpip.NICID + name string + linkEP LinkEndpoint + context NICContext + + stats NICStats + + mu struct { + sync.RWMutex + enabled bool + spoofing bool + promiscuous bool + primary map[tcpip.NetworkProtocolNumber][]*referencedNetworkEndpoint + endpoints map[NetworkEndpointID]*referencedNetworkEndpoint + addressRanges []tcpip.Subnet + mcastJoins map[NetworkEndpointID]uint32 + // packetEPs is protected by mu, but the contained PacketEndpoint + // values are not. + packetEPs map[tcpip.NetworkProtocolNumber][]PacketEndpoint + ndp ndpState + } +} + +// NICStats includes transmitted and received stats. +type NICStats struct { + Tx DirectionStats + Rx DirectionStats + + DisabledRx DirectionStats +} + +func makeNICStats() NICStats { + var s NICStats + tcpip.InitStatCounters(reflect.ValueOf(&s).Elem()) + return s +} + +// DirectionStats includes packet and byte counts. +type DirectionStats struct { + Packets *tcpip.StatCounter + Bytes *tcpip.StatCounter +} + +// PrimaryEndpointBehavior is an enumeration of an endpoint's primacy behavior. +type PrimaryEndpointBehavior int + +const ( + // CanBePrimaryEndpoint indicates the endpoint can be used as a primary + // endpoint for new connections with no local address. This is the + // default when calling NIC.AddAddress. + CanBePrimaryEndpoint PrimaryEndpointBehavior = iota + + // FirstPrimaryEndpoint indicates the endpoint should be the first + // primary endpoint considered. If there are multiple endpoints with + // this behavior, the most recently-added one will be first. + FirstPrimaryEndpoint + + // NeverPrimaryEndpoint indicates the endpoint should never be a + // primary endpoint. + NeverPrimaryEndpoint +) + +// newNIC returns a new NIC using the default NDP configurations from stack. +func newNIC(stack *Stack, id tcpip.NICID, name string, ep LinkEndpoint, ctx NICContext) *NIC { + // TODO(b/141011931): Validate a LinkEndpoint (ep) is valid. For + // example, make sure that the link address it provides is a valid + // unicast ethernet address. + + // TODO(b/143357959): RFC 8200 section 5 requires that IPv6 endpoints + // observe an MTU of at least 1280 bytes. Ensure that this requirement + // of IPv6 is supported on this endpoint's LinkEndpoint. + + nic := &NIC{ + stack: stack, + id: id, + name: name, + linkEP: ep, + context: ctx, + stats: makeNICStats(), + } + nic.mu.primary = make(map[tcpip.NetworkProtocolNumber][]*referencedNetworkEndpoint) + nic.mu.endpoints = make(map[NetworkEndpointID]*referencedNetworkEndpoint) + nic.mu.mcastJoins = make(map[NetworkEndpointID]uint32) + nic.mu.packetEPs = make(map[tcpip.NetworkProtocolNumber][]PacketEndpoint) + nic.mu.ndp = ndpState{ + nic: nic, + configs: stack.ndpConfigs, + dad: make(map[tcpip.Address]dadState), + defaultRouters: make(map[tcpip.Address]defaultRouterState), + onLinkPrefixes: make(map[tcpip.Subnet]onLinkPrefixState), + slaacPrefixes: make(map[tcpip.Subnet]slaacPrefixState), + } + nic.mu.ndp.initializeTempAddrState() + + // Register supported packet endpoint protocols. + for _, netProto := range header.Ethertypes { + nic.mu.packetEPs[netProto] = []PacketEndpoint{} + } + for _, netProto := range stack.networkProtocols { + nic.mu.packetEPs[netProto.Number()] = []PacketEndpoint{} + } + + nic.linkEP.Attach(nic) + + return nic +} + +// enabled returns true if n is enabled. +func (n *NIC) enabled() bool { + n.mu.RLock() + enabled := n.mu.enabled + n.mu.RUnlock() + return enabled +} + +// disable disables n. +// +// It undoes the work done by enable. +func (n *NIC) disable() *tcpip.Error { + n.mu.RLock() + enabled := n.mu.enabled + n.mu.RUnlock() + if !enabled { + return nil + } + + n.mu.Lock() + err := n.disableLocked() + n.mu.Unlock() + return err +} + +// disableLocked disables n. +// +// It undoes the work done by enable. +// +// n MUST be locked. +func (n *NIC) disableLocked() *tcpip.Error { + if !n.mu.enabled { + return nil + } + + // TODO(b/147015577): Should Routes that are currently bound to n be + // invalidated? Currently, Routes will continue to work when a NIC is enabled + // again, and applications may not know that the underlying NIC was ever + // disabled. + + if _, ok := n.stack.networkProtocols[header.IPv6ProtocolNumber]; ok { + n.mu.ndp.stopSolicitingRouters() + n.mu.ndp.cleanupState(false /* hostOnly */) + + // Stop DAD for all the unicast IPv6 endpoints that are in the + // permanentTentative state. + for _, r := range n.mu.endpoints { + if addr := r.ep.ID().LocalAddress; r.getKind() == permanentTentative && header.IsV6UnicastAddress(addr) { + n.mu.ndp.stopDuplicateAddressDetection(addr) + } + } + + // The NIC may have already left the multicast group. + if err := n.leaveGroupLocked(header.IPv6AllNodesMulticastAddress, false /* force */); err != nil && err != tcpip.ErrBadLocalAddress { + return err + } + } + + if _, ok := n.stack.networkProtocols[header.IPv4ProtocolNumber]; ok { + // The address may have already been removed. + if err := n.removePermanentAddressLocked(ipv4BroadcastAddr.AddressWithPrefix.Address); err != nil && err != tcpip.ErrBadLocalAddress { + return err + } + } + + n.mu.enabled = false + return nil +} + +// enable enables n. +// +// If the stack has IPv6 enabled, enable will join the IPv6 All-Nodes Multicast +// address (ff02::1), start DAD for permanent addresses, and start soliciting +// routers if the stack is not operating as a router. If the stack is also +// configured to auto-generate a link-local address, one will be generated. +func (n *NIC) enable() *tcpip.Error { + n.mu.RLock() + enabled := n.mu.enabled + n.mu.RUnlock() + if enabled { + return nil + } + + n.mu.Lock() + defer n.mu.Unlock() + + if n.mu.enabled { + return nil + } + + n.mu.enabled = true + + // Create an endpoint to receive broadcast packets on this interface. + if _, ok := n.stack.networkProtocols[header.IPv4ProtocolNumber]; ok { + if _, err := n.addAddressLocked(ipv4BroadcastAddr, NeverPrimaryEndpoint, permanent, static, false /* deprecated */); err != nil { + return err + } + } + + // Join the IPv6 All-Nodes Multicast group if the stack is configured to + // use IPv6. This is required to ensure that this node properly receives + // and responds to the various NDP messages that are destined to the + // all-nodes multicast address. An example is the Neighbor Advertisement + // when we perform Duplicate Address Detection, or Router Advertisement + // when we do Router Discovery. See RFC 4862, section 5.4.2 and RFC 4861 + // section 4.2 for more information. + // + // Also auto-generate an IPv6 link-local address based on the NIC's + // link address if it is configured to do so. Note, each interface is + // required to have IPv6 link-local unicast address, as per RFC 4291 + // section 2.1. + _, ok := n.stack.networkProtocols[header.IPv6ProtocolNumber] + if !ok { + return nil + } + + // Join the All-Nodes multicast group before starting DAD as responses to DAD + // (NDP NS) messages may be sent to the All-Nodes multicast group if the + // source address of the NDP NS is the unspecified address, as per RFC 4861 + // section 7.2.4. + if err := n.joinGroupLocked(header.IPv6ProtocolNumber, header.IPv6AllNodesMulticastAddress); err != nil { + return err + } + + // Perform DAD on the all the unicast IPv6 endpoints that are in the permanent + // state. + // + // Addresses may have aleady completed DAD but in the time since the NIC was + // last enabled, other devices may have acquired the same addresses. + for _, r := range n.mu.endpoints { + addr := r.ep.ID().LocalAddress + if k := r.getKind(); (k != permanent && k != permanentTentative) || !header.IsV6UnicastAddress(addr) { + continue + } + + r.setKind(permanentTentative) + if err := n.mu.ndp.startDuplicateAddressDetection(addr, r); err != nil { + return err + } + } + + // Do not auto-generate an IPv6 link-local address for loopback devices. + if n.stack.autoGenIPv6LinkLocal && !n.isLoopback() { + // The valid and preferred lifetime is infinite for the auto-generated + // link-local address. + n.mu.ndp.doSLAAC(header.IPv6LinkLocalPrefix.Subnet(), header.NDPInfiniteLifetime, header.NDPInfiniteLifetime) + } + + // 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.mu.ndp.startSolicitingRouters() + } + + return nil +} + +// remove detaches NIC from the link endpoint, and marks existing referenced +// network endpoints expired. This guarantees no packets between this NIC and +// the network stack. +func (n *NIC) remove() *tcpip.Error { + n.mu.Lock() + defer n.mu.Unlock() + + n.disableLocked() + + // TODO(b/151378115): come up with a better way to pick an error than the + // first one. + var err *tcpip.Error + + // Forcefully leave multicast groups. + for nid := range n.mu.mcastJoins { + if tempErr := n.leaveGroupLocked(nid.LocalAddress, true /* force */); tempErr != nil && err == nil { + err = tempErr + } + } + + // Remove permanent and permanentTentative addresses, so no packet goes out. + for nid, ref := range n.mu.endpoints { + switch ref.getKind() { + case permanentTentative, permanent: + if tempErr := n.removePermanentAddressLocked(nid.LocalAddress); tempErr != nil && err == nil { + err = tempErr + } + } + } + + // Detach from link endpoint, so no packet comes in. + n.linkEP.Attach(nil) + + 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 and NDP router solicitations will be stopped. +func (n *NIC) becomeIPv6Router() { + n.mu.Lock() + defer n.mu.Unlock() + + n.mu.ndp.cleanupState(true /* hostOnly */) + n.mu.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.mu.ndp.startSolicitingRouters() +} + +// setPromiscuousMode enables or disables promiscuous mode. +func (n *NIC) setPromiscuousMode(enable bool) { + n.mu.Lock() + n.mu.promiscuous = enable + n.mu.Unlock() +} + +func (n *NIC) isPromiscuousMode() bool { + n.mu.RLock() + rv := n.mu.promiscuous + n.mu.RUnlock() + return rv +} + +func (n *NIC) isLoopback() bool { + return n.linkEP.Capabilities()&CapabilityLoopback != 0 +} + +// setSpoofing enables or disables address spoofing. +func (n *NIC) setSpoofing(enable bool) { + n.mu.Lock() + n.mu.spoofing = enable + n.mu.Unlock() +} + +// primaryEndpoint will return the first non-deprecated endpoint if such an +// endpoint exists for the given protocol and remoteAddr. If no non-deprecated +// endpoint exists, the first deprecated endpoint will be returned. +// +// If an IPv6 primary endpoint is requested, Source Address Selection (as +// defined by RFC 6724 section 5) will be performed. +func (n *NIC) primaryEndpoint(protocol tcpip.NetworkProtocolNumber, remoteAddr tcpip.Address) *referencedNetworkEndpoint { + if protocol == header.IPv6ProtocolNumber && remoteAddr != "" { + return n.primaryIPv6Endpoint(remoteAddr) + } + + n.mu.RLock() + defer n.mu.RUnlock() + + var deprecatedEndpoint *referencedNetworkEndpoint + for _, r := range n.mu.primary[protocol] { + if !r.isValidForOutgoingRLocked() { + continue + } + + if !r.deprecated { + if r.tryIncRef() { + // r is not deprecated, so return it immediately. + // + // If we kept track of a deprecated endpoint, decrement its reference + // count since it was incremented when we decided to keep track of it. + if deprecatedEndpoint != nil { + deprecatedEndpoint.decRefLocked() + deprecatedEndpoint = nil + } + + return r + } + } else if deprecatedEndpoint == nil && r.tryIncRef() { + // We prefer an endpoint that is not deprecated, but we keep track of r in + // case n doesn't have any non-deprecated endpoints. + // + // If we end up finding a more preferred endpoint, r's reference count + // will be decremented when such an endpoint is found. + deprecatedEndpoint = r + } + } + + // n doesn't have any valid non-deprecated endpoints, so return + // deprecatedEndpoint (which may be nil if n doesn't have any valid deprecated + // endpoints either). + return deprecatedEndpoint +} + +// ipv6AddrCandidate is an IPv6 candidate for Source Address Selection (RFC +// 6724 section 5). +type ipv6AddrCandidate struct { + ref *referencedNetworkEndpoint + scope header.IPv6AddressScope +} + +// primaryIPv6Endpoint returns an IPv6 endpoint following Source Address +// Selection (RFC 6724 section 5). +// +// Note, only rules 1-3 and 7 are followed. +// +// remoteAddr must be a valid IPv6 address. +func (n *NIC) primaryIPv6Endpoint(remoteAddr tcpip.Address) *referencedNetworkEndpoint { + n.mu.RLock() + ref := n.primaryIPv6EndpointRLocked(remoteAddr) + n.mu.RUnlock() + return ref +} + +// primaryIPv6EndpointLocked returns an IPv6 endpoint following Source Address +// Selection (RFC 6724 section 5). +// +// Note, only rules 1-3 and 7 are followed. +// +// remoteAddr must be a valid IPv6 address. +// +// n.mu MUST be read locked. +func (n *NIC) primaryIPv6EndpointRLocked(remoteAddr tcpip.Address) *referencedNetworkEndpoint { + primaryAddrs := n.mu.primary[header.IPv6ProtocolNumber] + + if len(primaryAddrs) == 0 { + return nil + } + + // Create a candidate set of available addresses we can potentially use as a + // source address. + cs := make([]ipv6AddrCandidate, 0, len(primaryAddrs)) + for _, r := range primaryAddrs { + // If r is not valid for outgoing connections, it is not a valid endpoint. + if !r.isValidForOutgoingRLocked() { + continue + } + + addr := r.ep.ID().LocalAddress + scope, err := header.ScopeForIPv6Address(addr) + if err != nil { + // Should never happen as we got r from the primary IPv6 endpoint list and + // ScopeForIPv6Address only returns an error if addr is not an IPv6 + // address. + panic(fmt.Sprintf("header.ScopeForIPv6Address(%s): %s", addr, err)) + } + + cs = append(cs, ipv6AddrCandidate{ + ref: r, + scope: scope, + }) + } + + remoteScope, err := header.ScopeForIPv6Address(remoteAddr) + if err != nil { + // primaryIPv6Endpoint should never be called with an invalid IPv6 address. + panic(fmt.Sprintf("header.ScopeForIPv6Address(%s): %s", remoteAddr, err)) + } + + // Sort the addresses as per RFC 6724 section 5 rules 1-3. + // + // TODO(b/146021396): Implement rules 4-8 of RFC 6724 section 5. + sort.Slice(cs, func(i, j int) bool { + sa := cs[i] + sb := cs[j] + + // Prefer same address as per RFC 6724 section 5 rule 1. + if sa.ref.ep.ID().LocalAddress == remoteAddr { + return true + } + if sb.ref.ep.ID().LocalAddress == remoteAddr { + return false + } + + // Prefer appropriate scope as per RFC 6724 section 5 rule 2. + if sa.scope < sb.scope { + return sa.scope >= remoteScope + } else if sb.scope < sa.scope { + return sb.scope < remoteScope + } + + // Avoid deprecated addresses as per RFC 6724 section 5 rule 3. + if saDep, sbDep := sa.ref.deprecated, sb.ref.deprecated; saDep != sbDep { + // If sa is not deprecated, it is preferred over sb. + return sbDep + } + + // Prefer temporary addresses as per RFC 6724 section 5 rule 7. + if saTemp, sbTemp := sa.ref.configType == slaacTemp, sb.ref.configType == slaacTemp; saTemp != sbTemp { + return saTemp + } + + // sa and sb are equal, return the endpoint that is closest to the front of + // the primary endpoint list. + return i < j + }) + + // Return the most preferred address that can have its reference count + // incremented. + for _, c := range cs { + if r := c.ref; r.tryIncRef() { + return r + } + } + + return nil +} + +// hasPermanentAddrLocked returns true if n has a permanent (including currently +// tentative) address, addr. +func (n *NIC) hasPermanentAddrLocked(addr tcpip.Address) bool { + ref, ok := n.mu.endpoints[NetworkEndpointID{addr}] + + if !ok { + return false + } + + kind := ref.getKind() + + return kind == permanent || kind == permanentTentative +} + +type getRefBehaviour int + +const ( + // spoofing indicates that the NIC's spoofing flag should be observed when + // getting a NIC's referenced network endpoint. + spoofing getRefBehaviour = iota + + // promiscuous indicates that the NIC's promiscuous flag should be observed + // when getting a NIC's referenced network endpoint. + promiscuous +) + +func (n *NIC) getRef(protocol tcpip.NetworkProtocolNumber, dst tcpip.Address) *referencedNetworkEndpoint { + return n.getRefOrCreateTemp(protocol, dst, CanBePrimaryEndpoint, promiscuous) +} + +// findEndpoint finds the endpoint, if any, with the given address. +func (n *NIC) findEndpoint(protocol tcpip.NetworkProtocolNumber, address tcpip.Address, peb PrimaryEndpointBehavior) *referencedNetworkEndpoint { + return n.getRefOrCreateTemp(protocol, address, peb, spoofing) +} + +// getRefEpOrCreateTemp returns the referenced network endpoint for the given +// protocol and address. +// +// If none exists a temporary one may be created if we are in promiscuous mode +// or spoofing. Promiscuous mode will only be checked if promiscuous is true. +// Similarly, spoofing will only be checked if spoofing is true. +func (n *NIC) getRefOrCreateTemp(protocol tcpip.NetworkProtocolNumber, address tcpip.Address, peb PrimaryEndpointBehavior, tempRef getRefBehaviour) *referencedNetworkEndpoint { + n.mu.RLock() + + var spoofingOrPromiscuous bool + switch tempRef { + case spoofing: + spoofingOrPromiscuous = n.mu.spoofing + case promiscuous: + spoofingOrPromiscuous = n.mu.promiscuous + } + + if ref, ok := n.mu.endpoints[NetworkEndpointID{address}]; ok { + // An endpoint with this id exists, check if it can be used and return it. + if !ref.isAssignedRLocked(spoofingOrPromiscuous) { + n.mu.RUnlock() + return nil + } + + if ref.tryIncRef() { + n.mu.RUnlock() + return ref + } + } + + // A usable reference was not found, create a temporary one if requested by + // the caller or if the address is found in the NIC's subnets. + createTempEP := spoofingOrPromiscuous + if !createTempEP { + for _, sn := range n.mu.addressRanges { + // Skip the subnet address. + if address == sn.ID() { + continue + } + // For now just skip the broadcast address, until we support it. + // FIXME(b/137608825): Add support for sending/receiving directed + // (subnet) broadcast. + if address == sn.Broadcast() { + continue + } + if sn.Contains(address) { + createTempEP = true + break + } + } + } + + n.mu.RUnlock() + + if !createTempEP { + return nil + } + + // Try again with the lock in exclusive mode. If we still can't get the + // endpoint, create a new "temporary" endpoint. It will only exist while + // there's a route through it. + n.mu.Lock() + ref := n.getRefOrCreateTempLocked(protocol, address, peb) + n.mu.Unlock() + return ref +} + +/// getRefOrCreateTempLocked returns an existing endpoint for address or creates +/// and returns a temporary endpoint. +func (n *NIC) getRefOrCreateTempLocked(protocol tcpip.NetworkProtocolNumber, address tcpip.Address, peb PrimaryEndpointBehavior) *referencedNetworkEndpoint { + if ref, ok := n.mu.endpoints[NetworkEndpointID{address}]; ok { + // No need to check the type as we are ok with expired endpoints at this + // point. + if ref.tryIncRef() { + return ref + } + // tryIncRef failing means the endpoint is scheduled to be removed once the + // lock is released. Remove it here so we can create a new (temporary) one. + // The removal logic waiting for the lock handles this case. + n.removeEndpointLocked(ref) + } + + // Add a new temporary endpoint. + netProto, ok := n.stack.networkProtocols[protocol] + if !ok { + return nil + } + ref, _ := n.addAddressLocked(tcpip.ProtocolAddress{ + Protocol: protocol, + AddressWithPrefix: tcpip.AddressWithPrefix{ + Address: address, + PrefixLen: netProto.DefaultPrefixLen(), + }, + }, peb, temporary, static, false) + return ref +} + +// addAddressLocked adds a new protocolAddress to n. +// +// If n already has the address in a non-permanent state, and the kind given is +// permanent, that address will be promoted in place and its properties set to +// the properties provided. Otherwise, it returns tcpip.ErrDuplicateAddress. +func (n *NIC) addAddressLocked(protocolAddress tcpip.ProtocolAddress, peb PrimaryEndpointBehavior, kind networkEndpointKind, configType networkEndpointConfigType, deprecated bool) (*referencedNetworkEndpoint, *tcpip.Error) { + // TODO(b/141022673): Validate IP addresses before adding them. + + // Sanity check. + id := NetworkEndpointID{LocalAddress: protocolAddress.AddressWithPrefix.Address} + if ref, ok := n.mu.endpoints[id]; ok { + // Endpoint already exists. + if kind != permanent { + return nil, tcpip.ErrDuplicateAddress + } + switch ref.getKind() { + case permanentTentative, permanent: + // The NIC already have a permanent endpoint with that address. + return nil, tcpip.ErrDuplicateAddress + case permanentExpired, temporary: + // Promote the endpoint to become permanent and respect the new peb, + // configType and deprecated status. + if ref.tryIncRef() { + // TODO(b/147748385): Perform Duplicate Address Detection when promoting + // an IPv6 endpoint to permanent. + ref.setKind(permanent) + ref.deprecated = deprecated + ref.configType = configType + + refs := n.mu.primary[ref.protocol] + for i, r := range refs { + if r == ref { + switch peb { + case CanBePrimaryEndpoint: + return ref, nil + case FirstPrimaryEndpoint: + if i == 0 { + return ref, nil + } + n.mu.primary[r.protocol] = append(refs[:i], refs[i+1:]...) + case NeverPrimaryEndpoint: + n.mu.primary[r.protocol] = append(refs[:i], refs[i+1:]...) + return ref, nil + } + } + } + + n.insertPrimaryEndpointLocked(ref, peb) + + return ref, nil + } + // tryIncRef failing means the endpoint is scheduled to be removed once + // the lock is released. Remove it here so we can create a new + // (permanent) one. The removal logic waiting for the lock handles this + // case. + n.removeEndpointLocked(ref) + } + } + + netProto, ok := n.stack.networkProtocols[protocolAddress.Protocol] + if !ok { + return nil, tcpip.ErrUnknownProtocol + } + + // Create the new network endpoint. + ep, err := netProto.NewEndpoint(n.id, protocolAddress.AddressWithPrefix, n.stack, n, n.linkEP, n.stack) + if err != nil { + return nil, err + } + + isIPv6Unicast := protocolAddress.Protocol == header.IPv6ProtocolNumber && header.IsV6UnicastAddress(protocolAddress.AddressWithPrefix.Address) + + // If the address is an IPv6 address and it is a permanent address, + // mark it as tentative so it goes through the DAD process if the NIC is + // enabled. If the NIC is not enabled, DAD will be started when the NIC is + // enabled. + if isIPv6Unicast && kind == permanent { + kind = permanentTentative + } + + ref := &referencedNetworkEndpoint{ + refs: 1, + ep: ep, + nic: n, + protocol: protocolAddress.Protocol, + kind: kind, + configType: configType, + deprecated: deprecated, + } + + // Set up cache if link address resolution exists for this protocol. + if n.linkEP.Capabilities()&CapabilityResolutionRequired != 0 { + if _, ok := n.stack.linkAddrResolvers[protocolAddress.Protocol]; ok { + ref.linkCache = n.stack + } + } + + // If we are adding an IPv6 unicast address, join the solicited-node + // multicast address. + if isIPv6Unicast { + snmc := header.SolicitedNodeAddr(protocolAddress.AddressWithPrefix.Address) + if err := n.joinGroupLocked(protocolAddress.Protocol, snmc); err != nil { + return nil, err + } + } + + n.mu.endpoints[id] = ref + + n.insertPrimaryEndpointLocked(ref, peb) + + // If we are adding a tentative IPv6 address, start DAD if the NIC is enabled. + if isIPv6Unicast && kind == permanentTentative && n.mu.enabled { + if err := n.mu.ndp.startDuplicateAddressDetection(protocolAddress.AddressWithPrefix.Address, ref); err != nil { + return nil, err + } + } + + return ref, nil +} + +// AddAddress adds a new address to n, so that it starts accepting packets +// targeted at the given address (and network protocol). +func (n *NIC) AddAddress(protocolAddress tcpip.ProtocolAddress, peb PrimaryEndpointBehavior) *tcpip.Error { + // Add the endpoint. + n.mu.Lock() + _, err := n.addAddressLocked(protocolAddress, peb, permanent, static, false /* deprecated */) + n.mu.Unlock() + + return err +} + +// AllAddresses returns all addresses (primary and non-primary) associated with +// this NIC. +func (n *NIC) AllAddresses() []tcpip.ProtocolAddress { + n.mu.RLock() + defer n.mu.RUnlock() + + addrs := make([]tcpip.ProtocolAddress, 0, len(n.mu.endpoints)) + for nid, ref := range n.mu.endpoints { + // Don't include tentative, expired or temporary endpoints to + // avoid confusion and prevent the caller from using those. + switch ref.getKind() { + case permanentExpired, temporary: + continue + } + + addrs = append(addrs, tcpip.ProtocolAddress{ + Protocol: ref.protocol, + AddressWithPrefix: tcpip.AddressWithPrefix{ + Address: nid.LocalAddress, + PrefixLen: ref.ep.PrefixLen(), + }, + }) + } + return addrs +} + +// PrimaryAddresses returns the primary addresses associated with this NIC. +func (n *NIC) PrimaryAddresses() []tcpip.ProtocolAddress { + n.mu.RLock() + defer n.mu.RUnlock() + + var addrs []tcpip.ProtocolAddress + for proto, list := range n.mu.primary { + for _, ref := range list { + // Don't include tentative, expired or tempory endpoints + // to avoid confusion and prevent the caller from using + // those. + switch ref.getKind() { + case permanentTentative, permanentExpired, temporary: + continue + } + + addrs = append(addrs, tcpip.ProtocolAddress{ + Protocol: proto, + AddressWithPrefix: tcpip.AddressWithPrefix{ + Address: ref.ep.ID().LocalAddress, + PrefixLen: ref.ep.PrefixLen(), + }, + }) + } + } + return addrs +} + +// primaryAddress returns the primary address associated with this NIC. +// +// primaryAddress will return the first non-deprecated address if such an +// address exists. If no non-deprecated address exists, the first deprecated +// address will be returned. +func (n *NIC) primaryAddress(proto tcpip.NetworkProtocolNumber) tcpip.AddressWithPrefix { + n.mu.RLock() + defer n.mu.RUnlock() + + list, ok := n.mu.primary[proto] + if !ok { + return tcpip.AddressWithPrefix{} + } + + var deprecatedEndpoint *referencedNetworkEndpoint + for _, ref := range list { + // Don't include tentative, expired or tempory endpoints to avoid confusion + // and prevent the caller from using those. + switch ref.getKind() { + case permanentTentative, permanentExpired, temporary: + continue + } + + if !ref.deprecated { + return tcpip.AddressWithPrefix{ + Address: ref.ep.ID().LocalAddress, + PrefixLen: ref.ep.PrefixLen(), + } + } + + if deprecatedEndpoint == nil { + deprecatedEndpoint = ref + } + } + + if deprecatedEndpoint != nil { + return tcpip.AddressWithPrefix{ + Address: deprecatedEndpoint.ep.ID().LocalAddress, + PrefixLen: deprecatedEndpoint.ep.PrefixLen(), + } + } + + return tcpip.AddressWithPrefix{} +} + +// AddAddressRange adds a range of addresses to n, so that it starts accepting +// packets targeted at the given addresses and network protocol. The range is +// given by a subnet address, and all addresses contained in the subnet are +// used except for the subnet address itself and the subnet's broadcast +// address. +func (n *NIC) AddAddressRange(protocol tcpip.NetworkProtocolNumber, subnet tcpip.Subnet) { + n.mu.Lock() + n.mu.addressRanges = append(n.mu.addressRanges, subnet) + n.mu.Unlock() +} + +// RemoveAddressRange removes the given address range from n. +func (n *NIC) RemoveAddressRange(subnet tcpip.Subnet) { + n.mu.Lock() + + // Use the same underlying array. + tmp := n.mu.addressRanges[:0] + for _, sub := range n.mu.addressRanges { + if sub != subnet { + tmp = append(tmp, sub) + } + } + n.mu.addressRanges = tmp + + n.mu.Unlock() +} + +// AddressRanges returns the Subnets associated with this NIC. +func (n *NIC) AddressRanges() []tcpip.Subnet { + n.mu.RLock() + defer n.mu.RUnlock() + sns := make([]tcpip.Subnet, 0, len(n.mu.addressRanges)+len(n.mu.endpoints)) + for nid := range n.mu.endpoints { + sn, err := tcpip.NewSubnet(nid.LocalAddress, tcpip.AddressMask(strings.Repeat("\xff", len(nid.LocalAddress)))) + if err != nil { + // This should never happen as the mask has been carefully crafted to + // match the address. + panic("Invalid endpoint subnet: " + err.Error()) + } + sns = append(sns, sn) + } + return append(sns, n.mu.addressRanges...) +} + +// insertPrimaryEndpointLocked adds r to n's primary endpoint list as required +// by peb. +// +// n MUST be locked. +func (n *NIC) insertPrimaryEndpointLocked(r *referencedNetworkEndpoint, peb PrimaryEndpointBehavior) { + switch peb { + case CanBePrimaryEndpoint: + n.mu.primary[r.protocol] = append(n.mu.primary[r.protocol], r) + case FirstPrimaryEndpoint: + n.mu.primary[r.protocol] = append([]*referencedNetworkEndpoint{r}, n.mu.primary[r.protocol]...) + } +} + +func (n *NIC) removeEndpointLocked(r *referencedNetworkEndpoint) { + id := *r.ep.ID() + + // Nothing to do if the reference has already been replaced with a different + // one. This happens in the case where 1) this endpoint's ref count hit zero + // and was waiting (on the lock) to be removed and 2) the same address was + // re-added in the meantime by removing this endpoint from the list and + // adding a new one. + if n.mu.endpoints[id] != r { + return + } + + if r.getKind() == permanent { + panic("Reference count dropped to zero before being removed") + } + + delete(n.mu.endpoints, id) + refs := n.mu.primary[r.protocol] + for i, ref := range refs { + if ref == r { + n.mu.primary[r.protocol] = append(refs[:i], refs[i+1:]...) + refs[len(refs)-1] = nil + break + } + } + + r.ep.Close() +} + +func (n *NIC) removeEndpoint(r *referencedNetworkEndpoint) { + n.mu.Lock() + n.removeEndpointLocked(r) + n.mu.Unlock() +} + +func (n *NIC) removePermanentAddressLocked(addr tcpip.Address) *tcpip.Error { + r, ok := n.mu.endpoints[NetworkEndpointID{addr}] + if !ok { + return tcpip.ErrBadLocalAddress + } + + kind := r.getKind() + if kind != permanent && kind != permanentTentative { + return tcpip.ErrBadLocalAddress + } + + switch r.protocol { + case header.IPv6ProtocolNumber: + return n.removePermanentIPv6EndpointLocked(r, true /* allowSLAACInvalidation */) + default: + r.expireLocked() + return nil + } +} + +func (n *NIC) removePermanentIPv6EndpointLocked(r *referencedNetworkEndpoint, allowSLAACInvalidation bool) *tcpip.Error { + addr := r.addrWithPrefix() + + isIPv6Unicast := header.IsV6UnicastAddress(addr.Address) + + if isIPv6Unicast { + n.mu.ndp.stopDuplicateAddressDetection(addr.Address) + + // If we are removing an address generated via SLAAC, cleanup + // its SLAAC resources and notify the integrator. + switch r.configType { + case slaac: + n.mu.ndp.cleanupSLAACAddrResourcesAndNotify(addr, allowSLAACInvalidation) + case slaacTemp: + n.mu.ndp.cleanupTempSLAACAddrResourcesAndNotify(addr, allowSLAACInvalidation) + } + } + + r.expireLocked() + + // At this point the endpoint is deleted. + + // If we are removing an IPv6 unicast address, leave the solicited-node + // multicast address. + // + // We ignore the tcpip.ErrBadLocalAddress error because the solicited-node + // multicast group may be left by user action. + if isIPv6Unicast { + snmc := header.SolicitedNodeAddr(addr.Address) + if err := n.leaveGroupLocked(snmc, false /* force */); err != nil && err != tcpip.ErrBadLocalAddress { + return err + } + } + + return nil +} + +// RemoveAddress removes an address from n. +func (n *NIC) RemoveAddress(addr tcpip.Address) *tcpip.Error { + n.mu.Lock() + defer n.mu.Unlock() + return n.removePermanentAddressLocked(addr) +} + +// joinGroup adds a new endpoint for the given multicast address, if none +// exists yet. Otherwise it just increments its count. +func (n *NIC) joinGroup(protocol tcpip.NetworkProtocolNumber, addr tcpip.Address) *tcpip.Error { + n.mu.Lock() + defer n.mu.Unlock() + + return n.joinGroupLocked(protocol, addr) +} + +// joinGroupLocked adds a new endpoint for the given multicast address, if none +// exists yet. Otherwise it just increments its count. n MUST be locked before +// joinGroupLocked is called. +func (n *NIC) joinGroupLocked(protocol tcpip.NetworkProtocolNumber, addr tcpip.Address) *tcpip.Error { + // TODO(b/143102137): When implementing MLD, make sure MLD packets are + // not sent unless a valid link-local address is available for use on n + // as an MLD packet's source address must be a link-local address as + // outlined in RFC 3810 section 5. + + id := NetworkEndpointID{addr} + joins := n.mu.mcastJoins[id] + if joins == 0 { + netProto, ok := n.stack.networkProtocols[protocol] + if !ok { + return tcpip.ErrUnknownProtocol + } + if _, err := n.addAddressLocked(tcpip.ProtocolAddress{ + Protocol: protocol, + AddressWithPrefix: tcpip.AddressWithPrefix{ + Address: addr, + PrefixLen: netProto.DefaultPrefixLen(), + }, + }, NeverPrimaryEndpoint, permanent, static, false /* deprecated */); err != nil { + return err + } + } + n.mu.mcastJoins[id] = joins + 1 + return nil +} + +// leaveGroup decrements the count for the given multicast address, and when it +// reaches zero removes the endpoint for this address. +func (n *NIC) leaveGroup(addr tcpip.Address) *tcpip.Error { + n.mu.Lock() + defer n.mu.Unlock() + + return n.leaveGroupLocked(addr, false /* force */) +} + +// leaveGroupLocked decrements the count for the given multicast address, and +// when it reaches zero removes the endpoint for this address. n MUST be locked +// before leaveGroupLocked is called. +// +// If force is true, then the count for the multicast addres is ignored and the +// endpoint will be removed immediately. +func (n *NIC) leaveGroupLocked(addr tcpip.Address, force bool) *tcpip.Error { + id := NetworkEndpointID{addr} + joins, ok := n.mu.mcastJoins[id] + if !ok { + // There are no joins with this address on this NIC. + return tcpip.ErrBadLocalAddress + } + + joins-- + if force || joins == 0 { + // There are no outstanding joins or we are forced to leave, clean up. + delete(n.mu.mcastJoins, id) + return n.removePermanentAddressLocked(addr) + } + + n.mu.mcastJoins[id] = joins + return nil +} + +// isInGroup returns true if n has joined the multicast group addr. +func (n *NIC) isInGroup(addr tcpip.Address) bool { + n.mu.RLock() + joins := n.mu.mcastJoins[NetworkEndpointID{addr}] + n.mu.RUnlock() + + return joins != 0 +} + +func handlePacket(protocol tcpip.NetworkProtocolNumber, dst, src tcpip.Address, localLinkAddr, remotelinkAddr tcpip.LinkAddress, ref *referencedNetworkEndpoint, pkt *PacketBuffer) { + r := makeRoute(protocol, dst, src, localLinkAddr, ref, false /* handleLocal */, false /* multicastLoop */) + r.RemoteLinkAddress = remotelinkAddr + + ref.ep.HandlePacket(&r, pkt) + ref.decRef() +} + +// DeliverNetworkPacket finds the appropriate network protocol endpoint and +// hands the packet over for further processing. This function is called when +// the NIC receives a packet from the link endpoint. +// Note that the ownership of the slice backing vv is retained by the caller. +// This rule applies only to the slice itself, not to the items of the slice; +// the ownership of the items is not retained by the caller. +func (n *NIC) DeliverNetworkPacket(remote, local tcpip.LinkAddress, protocol tcpip.NetworkProtocolNumber, pkt *PacketBuffer) { + n.mu.RLock() + enabled := n.mu.enabled + // If the NIC is not yet enabled, don't receive any packets. + if !enabled { + n.mu.RUnlock() + + n.stats.DisabledRx.Packets.Increment() + n.stats.DisabledRx.Bytes.IncrementBy(uint64(pkt.Data.Size())) + return + } + + n.stats.Rx.Packets.Increment() + n.stats.Rx.Bytes.IncrementBy(uint64(pkt.Data.Size())) + + netProto, ok := n.stack.networkProtocols[protocol] + if !ok { + n.mu.RUnlock() + n.stack.stats.UnknownProtocolRcvdPackets.Increment() + return + } + + // If no local link layer address is provided, assume it was sent + // directly to this NIC. + if local == "" { + local = n.linkEP.LinkAddress() + } + + // Are any packet sockets listening for this network protocol? + packetEPs := n.mu.packetEPs[protocol] + // Check whether there are packet sockets listening for every protocol. + // If we received a packet with protocol EthernetProtocolAll, then the + // previous for loop will have handled it. + if protocol != header.EthernetProtocolAll { + packetEPs = append(packetEPs, n.mu.packetEPs[header.EthernetProtocolAll]...) + } + n.mu.RUnlock() + for _, ep := range packetEPs { + ep.HandlePacket(n.id, local, protocol, pkt.Clone()) + } + + if netProto.Number() == header.IPv4ProtocolNumber || netProto.Number() == header.IPv6ProtocolNumber { + n.stack.stats.IP.PacketsReceived.Increment() + } + + // Parse headers. + transProtoNum, hasTransportHdr, ok := netProto.Parse(pkt) + if !ok { + // The packet is too small to contain a network header. + n.stack.stats.MalformedRcvdPackets.Increment() + return + } + if hasTransportHdr { + // Parse the transport header if present. + if state, ok := n.stack.transportProtocols[transProtoNum]; ok { + state.proto.Parse(pkt) + } + } + + src, dst := netProto.ParseAddresses(pkt.NetworkHeader) + + if n.stack.handleLocal && !n.isLoopback() && n.getRef(protocol, src) != nil { + // The source address is one of our own, so we never should have gotten a + // packet like this unless handleLocal is false. Loopback also calls this + // function even though the packets didn't come from the physical interface + // so don't drop those. + n.stack.stats.IP.InvalidSourceAddressesReceived.Increment() + return + } + + // TODO(gvisor.dev/issue/170): Not supporting iptables for IPv6 yet. + // Loopback traffic skips the prerouting chain. + if protocol == header.IPv4ProtocolNumber && !n.isLoopback() { + // iptables filtering. + ipt := n.stack.IPTables() + address := n.primaryAddress(protocol) + if ok := ipt.Check(Prerouting, pkt, nil, nil, address.Address, ""); !ok { + // iptables is telling us to drop the packet. + return + } + } + + if ref := n.getRef(protocol, dst); ref != nil { + handlePacket(protocol, dst, src, n.linkEP.LinkAddress(), remote, ref, pkt) + return + } + + // This NIC doesn't care about the packet. Find a NIC that cares about the + // packet and forward it to the NIC. + // + // TODO: Should we be forwarding the packet even if promiscuous? + if n.stack.Forwarding() { + r, err := n.stack.FindRoute(0, "", dst, protocol, false /* multicastLoop */) + if err != nil { + n.stack.stats.IP.InvalidDestinationAddressesReceived.Increment() + return + } + + // Found a NIC. + n := r.ref.nic + n.mu.RLock() + ref, ok := n.mu.endpoints[NetworkEndpointID{dst}] + ok = ok && ref.isValidForOutgoingRLocked() && ref.tryIncRef() + n.mu.RUnlock() + if ok { + r.LocalLinkAddress = n.linkEP.LinkAddress() + r.RemoteLinkAddress = remote + r.RemoteAddress = src + // TODO(b/123449044): Update the source NIC as well. + ref.ep.HandlePacket(&r, pkt) + ref.decRef() + r.Release() + return + } + + // n doesn't have a destination endpoint. + // Send the packet out of n. + // TODO(b/128629022): move this logic to route.WritePacket. + if ch, err := r.Resolve(nil); err != nil { + if err == tcpip.ErrWouldBlock { + n.stack.forwarder.enqueue(ch, n, &r, protocol, pkt) + // forwarder will release route. + return + } + n.stack.stats.IP.InvalidDestinationAddressesReceived.Increment() + r.Release() + return + } + + // The link-address resolution finished immediately. + n.forwardPacket(&r, protocol, pkt) + r.Release() + return + } + + // If a packet socket handled the packet, don't treat it as invalid. + if len(packetEPs) == 0 { + n.stack.stats.IP.InvalidDestinationAddressesReceived.Increment() + } +} + +func (n *NIC) forwardPacket(r *Route, protocol tcpip.NetworkProtocolNumber, pkt *PacketBuffer) { + // TODO(b/143425874) Decrease the TTL field in forwarded packets. + // TODO(b/151227689): Avoid copying the packet when forwarding. We can do this + // by having lower layers explicity write each header instead of just + // pkt.Header. + + // pkt may have set its NetworkHeader and TransportHeader. If we're + // forwarding, we'll have to copy them into pkt.Header. + pkt.Header = buffer.NewPrependable(int(n.linkEP.MaxHeaderLength()) + len(pkt.NetworkHeader) + len(pkt.TransportHeader)) + if n := copy(pkt.Header.Prepend(len(pkt.TransportHeader)), pkt.TransportHeader); n != len(pkt.TransportHeader) { + panic(fmt.Sprintf("copied %d bytes, expected %d", n, len(pkt.TransportHeader))) + } + if n := copy(pkt.Header.Prepend(len(pkt.NetworkHeader)), pkt.NetworkHeader); n != len(pkt.NetworkHeader) { + panic(fmt.Sprintf("copied %d bytes, expected %d", n, len(pkt.NetworkHeader))) + } + + // WritePacket takes ownership of pkt, calculate numBytes first. + numBytes := pkt.Header.UsedLength() + pkt.Data.Size() + + if err := n.linkEP.WritePacket(r, nil /* gso */, protocol, pkt); err != nil { + r.Stats().IP.OutgoingPacketErrors.Increment() + return + } + + n.stats.Tx.Packets.Increment() + n.stats.Tx.Bytes.IncrementBy(uint64(numBytes)) +} + +// DeliverTransportPacket delivers the packets to the appropriate transport +// protocol endpoint. +func (n *NIC) DeliverTransportPacket(r *Route, protocol tcpip.TransportProtocolNumber, pkt *PacketBuffer) { + state, ok := n.stack.transportProtocols[protocol] + if !ok { + n.stack.stats.UnknownProtocolRcvdPackets.Increment() + return + } + + transProto := state.proto + + // Raw socket packets are delivered based solely on the transport + // protocol number. We do not inspect the payload to ensure it's + // validly formed. + n.stack.demux.deliverRawPacket(r, protocol, pkt) + + // TransportHeader is nil only when pkt is an ICMP packet or was reassembled + // from fragments. + if pkt.TransportHeader == nil { + // TODO(gvisor.dev/issue/170): ICMP packets don't have their TransportHeader + // fields set yet, parse it here. See icmp/protocol.go:protocol.Parse for a + // full explanation. + if protocol == header.ICMPv4ProtocolNumber || protocol == header.ICMPv6ProtocolNumber { + // ICMP packets may be longer, but until icmp.Parse is implemented, here + // we parse it using the minimum size. + transHeader, ok := pkt.Data.PullUp(transProto.MinimumPacketSize()) + if !ok { + n.stack.stats.MalformedRcvdPackets.Increment() + return + } + pkt.TransportHeader = transHeader + pkt.Data.TrimFront(len(pkt.TransportHeader)) + } else { + // This is either a bad packet or was re-assembled from fragments. + transProto.Parse(pkt) + } + } + + if len(pkt.TransportHeader) < transProto.MinimumPacketSize() { + n.stack.stats.MalformedRcvdPackets.Increment() + return + } + + srcPort, dstPort, err := transProto.ParsePorts(pkt.TransportHeader) + if err != nil { + n.stack.stats.MalformedRcvdPackets.Increment() + return + } + + id := TransportEndpointID{dstPort, r.LocalAddress, srcPort, r.RemoteAddress} + if n.stack.demux.deliverPacket(r, protocol, pkt, id) { + return + } + + // Try to deliver to per-stack default handler. + if state.defaultHandler != nil { + if state.defaultHandler(r, id, pkt) { + return + } + } + + // We could not find an appropriate destination for this packet, so + // deliver it to the global handler. + if !transProto.HandleUnknownDestinationPacket(r, id, pkt) { + n.stack.stats.MalformedRcvdPackets.Increment() + } +} + +// DeliverTransportControlPacket delivers control packets to the appropriate +// transport protocol endpoint. +func (n *NIC) DeliverTransportControlPacket(local, remote tcpip.Address, net tcpip.NetworkProtocolNumber, trans tcpip.TransportProtocolNumber, typ ControlType, extra uint32, pkt *PacketBuffer) { + state, ok := n.stack.transportProtocols[trans] + if !ok { + return + } + + transProto := state.proto + + // ICMPv4 only guarantees that 8 bytes of the transport protocol will + // be present in the payload. We know that the ports are within the + // first 8 bytes for all known transport protocols. + transHeader, ok := pkt.Data.PullUp(8) + if !ok { + return + } + + srcPort, dstPort, err := transProto.ParsePorts(transHeader) + if err != nil { + return + } + + id := TransportEndpointID{srcPort, local, dstPort, remote} + if n.stack.demux.deliverControlPacket(n, net, trans, typ, extra, pkt, id) { + return + } +} + +// ID returns the identifier of n. +func (n *NIC) ID() tcpip.NICID { + return n.id +} + +// Name returns the name of n. +func (n *NIC) Name() string { + return n.name +} + +// Stack returns the instance of the Stack that owns this NIC. +func (n *NIC) Stack() *Stack { + return n.stack +} + +// LinkEndpoint returns the link endpoint of n. +func (n *NIC) LinkEndpoint() LinkEndpoint { + return n.linkEP +} + +// isAddrTentative returns true if addr is tentative on n. +// +// Note that if addr is not associated with n, then this function will return +// false. It will only return true if the address is associated with the NIC +// AND it is tentative. +func (n *NIC) isAddrTentative(addr tcpip.Address) bool { + n.mu.RLock() + defer n.mu.RUnlock() + + ref, ok := n.mu.endpoints[NetworkEndpointID{addr}] + if !ok { + return false + } + + return ref.getKind() == permanentTentative +} + +// dupTentativeAddrDetected attempts to inform n that a tentative addr is a +// duplicate on a link. +// +// dupTentativeAddrDetected will remove the tentative address if it exists. If +// the address was generated via SLAAC, an attempt will be made to generate a +// new address. +func (n *NIC) dupTentativeAddrDetected(addr tcpip.Address) *tcpip.Error { + n.mu.Lock() + defer n.mu.Unlock() + + ref, ok := n.mu.endpoints[NetworkEndpointID{addr}] + if !ok { + return tcpip.ErrBadAddress + } + + if ref.getKind() != permanentTentative { + return tcpip.ErrInvalidEndpointState + } + + // If the address is a SLAAC address, do not invalidate its SLAAC prefix as a + // new address will be generated for it. + if err := n.removePermanentIPv6EndpointLocked(ref, false /* allowSLAACInvalidation */); err != nil { + return err + } + + prefix := ref.addrWithPrefix().Subnet() + + switch ref.configType { + case slaac: + n.mu.ndp.regenerateSLAACAddr(prefix) + case slaacTemp: + // Do not reset the generation attempts counter for the prefix as the + // temporary address is being regenerated in response to a DAD conflict. + n.mu.ndp.regenerateTempSLAACAddr(prefix, false /* resetGenAttempts */) + } + + return nil +} + +// setNDPConfigs sets the NDP configurations for n. +// +// Note, if c contains invalid NDP configuration values, it will be fixed to +// use default values for the erroneous values. +func (n *NIC) setNDPConfigs(c NDPConfigurations) { + c.validate() + + n.mu.Lock() + n.mu.ndp.configs = c + n.mu.Unlock() +} + +// handleNDPRA handles an NDP Router Advertisement message that arrived on n. +func (n *NIC) handleNDPRA(ip tcpip.Address, ra header.NDPRouterAdvert) { + n.mu.Lock() + defer n.mu.Unlock() + + n.mu.ndp.handleRA(ip, ra) +} + +type networkEndpointKind int32 + +const ( + // A permanentTentative endpoint is a permanent address that is not yet + // considered to be fully bound to an interface in the traditional + // sense. That is, the address is associated with a NIC, but packets + // destined to the address MUST NOT be accepted and MUST be silently + // dropped, and the address MUST NOT be used as a source address for + // outgoing packets. For IPv6, addresses will be of this kind until + // NDP's Duplicate Address Detection has resolved, or be deleted if + // the process results in detecting a duplicate address. + permanentTentative networkEndpointKind = iota + + // A permanent endpoint is created by adding a permanent address (vs. a + // temporary one) to the NIC. Its reference count is biased by 1 to avoid + // removal when no route holds a reference to it. It is removed by explicitly + // removing the permanent address from the NIC. + permanent + + // An expired permanent endpoint is a permanent endpoint that had its address + // removed from the NIC, and it is waiting to be removed once no more routes + // hold a reference to it. This is achieved by decreasing its reference count + // by 1. If its address is re-added before the endpoint is removed, its type + // changes back to permanent and its reference count increases by 1 again. + permanentExpired + + // A temporary endpoint is created for spoofing outgoing packets, or when in + // promiscuous mode and accepting incoming packets that don't match any + // permanent endpoint. Its reference count is not biased by 1 and the + // endpoint is removed immediately when no more route holds a reference to + // it. A temporary endpoint can be promoted to permanent if its address + // is added permanently. + temporary +) + +func (n *NIC) registerPacketEndpoint(netProto tcpip.NetworkProtocolNumber, ep PacketEndpoint) *tcpip.Error { + n.mu.Lock() + defer n.mu.Unlock() + + eps, ok := n.mu.packetEPs[netProto] + if !ok { + return tcpip.ErrNotSupported + } + n.mu.packetEPs[netProto] = append(eps, ep) + + return nil +} + +func (n *NIC) unregisterPacketEndpoint(netProto tcpip.NetworkProtocolNumber, ep PacketEndpoint) { + n.mu.Lock() + defer n.mu.Unlock() + + eps, ok := n.mu.packetEPs[netProto] + if !ok { + return + } + + for i, epOther := range eps { + if epOther == ep { + n.mu.packetEPs[netProto] = append(eps[:i], eps[i+1:]...) + return + } + } +} + +type networkEndpointConfigType int32 + +const ( + // A statically configured endpoint is an address that was added by + // some user-specified action (adding an explicit address, joining a + // multicast group). + static networkEndpointConfigType = iota + + // A SLAAC configured endpoint is an IPv6 endpoint that was added by + // SLAAC as per RFC 4862 section 5.5.3. + slaac + + // A temporary SLAAC configured endpoint is an IPv6 endpoint that was added by + // SLAAC as per RFC 4941. Temporary SLAAC addresses are short-lived and are + // not expected to be valid (or preferred) forever; hence the term temporary. + slaacTemp +) + +type referencedNetworkEndpoint struct { + ep NetworkEndpoint + nic *NIC + protocol tcpip.NetworkProtocolNumber + + // linkCache is set if link address resolution is enabled for this + // protocol. Set to nil otherwise. + linkCache LinkAddressCache + + // refs is counting references held for this endpoint. When refs hits zero it + // triggers the automatic removal of the endpoint from the NIC. + refs int32 + + // networkEndpointKind must only be accessed using {get,set}Kind(). + kind networkEndpointKind + + // configType is the method that was used to configure this endpoint. + // This must never change except during endpoint creation and promotion to + // permanent. + configType networkEndpointConfigType + + // deprecated indicates whether or not the endpoint should be considered + // deprecated. That is, when deprecated is true, other endpoints that are not + // deprecated should be preferred. + deprecated bool +} + +func (r *referencedNetworkEndpoint) addrWithPrefix() tcpip.AddressWithPrefix { + return tcpip.AddressWithPrefix{ + Address: r.ep.ID().LocalAddress, + PrefixLen: r.ep.PrefixLen(), + } +} + +func (r *referencedNetworkEndpoint) getKind() networkEndpointKind { + return networkEndpointKind(atomic.LoadInt32((*int32)(&r.kind))) +} + +func (r *referencedNetworkEndpoint) setKind(kind networkEndpointKind) { + atomic.StoreInt32((*int32)(&r.kind), int32(kind)) +} + +// isValidForOutgoing returns true if the endpoint can be used to send out a +// packet. It requires the endpoint to not be marked expired (i.e., its address) +// has been removed) unless the NIC is in spoofing mode, or temporary. +func (r *referencedNetworkEndpoint) isValidForOutgoing() bool { + r.nic.mu.RLock() + defer r.nic.mu.RUnlock() + + return r.isValidForOutgoingRLocked() +} + +// isValidForOutgoingRLocked is the same as isValidForOutgoing but requires +// r.nic.mu to be read locked. +func (r *referencedNetworkEndpoint) isValidForOutgoingRLocked() bool { + if !r.nic.mu.enabled { + return false + } + + return r.isAssignedRLocked(r.nic.mu.spoofing) +} + +// isAssignedRLocked returns true if r is considered to be assigned to the NIC. +// +// r.nic.mu must be read locked. +func (r *referencedNetworkEndpoint) isAssignedRLocked(spoofingOrPromiscuous bool) bool { + switch r.getKind() { + case permanentTentative: + return false + case permanentExpired: + return spoofingOrPromiscuous + default: + return true + } +} + +// expireLocked decrements the reference count and marks the permanent endpoint +// as expired. +func (r *referencedNetworkEndpoint) expireLocked() { + r.setKind(permanentExpired) + r.decRefLocked() +} + +// decRef decrements the ref count and cleans up the endpoint once it reaches +// zero. +func (r *referencedNetworkEndpoint) decRef() { + if atomic.AddInt32(&r.refs, -1) == 0 { + r.nic.removeEndpoint(r) + } +} + +// decRefLocked is the same as decRef but assumes that the NIC.mu mutex is +// locked. +func (r *referencedNetworkEndpoint) decRefLocked() { + if atomic.AddInt32(&r.refs, -1) == 0 { + r.nic.removeEndpointLocked(r) + } +} + +// incRef increments the ref count. It must only be called when the caller is +// known to be holding a reference to the endpoint, otherwise tryIncRef should +// be used. +func (r *referencedNetworkEndpoint) incRef() { + atomic.AddInt32(&r.refs, 1) +} + +// tryIncRef attempts to increment the ref count from n to n+1, but only if n is +// not zero. That is, it will increment the count if the endpoint is still +// alive, and do nothing if it has already been clean up. +func (r *referencedNetworkEndpoint) tryIncRef() bool { + for { + v := atomic.LoadInt32(&r.refs) + if v == 0 { + return false + } + + if atomic.CompareAndSwapInt32(&r.refs, v, v+1) { + return true + } + } +} + +// stack returns the Stack instance that owns the underlying endpoint. +func (r *referencedNetworkEndpoint) stack() *Stack { + return r.nic.stack +} |