diff options
Diffstat (limited to 'pkg/tcpip/network/ipv4/ipv4.go')
| -rw-r--r-- | pkg/tcpip/network/ipv4/ipv4.go | 82 |
1 files changed, 51 insertions, 31 deletions
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go index e7c58ae0a..41e548c85 100644 --- a/pkg/tcpip/network/ipv4/ipv4.go +++ b/pkg/tcpip/network/ipv4/ipv4.go @@ -176,7 +176,11 @@ func (e *endpoint) DefaultTTL() uint8 { // MTU implements stack.NetworkEndpoint.MTU. It returns the link-layer MTU minus // the network layer max header length. func (e *endpoint) MTU() uint32 { - return calculateMTU(e.nic.MTU()) + networkMTU, err := calculateNetworkMTU(e.nic.MTU(), header.IPv4MinimumSize) + if err != nil { + return 0 + } + return networkMTU } // MaxHeaderLength returns the maximum length needed by ipv4 headers (and @@ -211,18 +215,15 @@ func (e *endpoint) addIPHeader(r *stack.Route, pkt *stack.PacketBuffer, params s pkt.NetworkProtocolNumber = ProtocolNumber } -func (e *endpoint) packetMustBeFragmented(pkt *stack.PacketBuffer, gso *stack.GSO) bool { - return (gso == nil || gso.Type == stack.GSONone) && pkt.Size() > int(e.nic.MTU()) -} - // handleFragments fragments pkt and calls the handler function on each // fragment. It returns the number of fragments handled and the number of // fragments left to be processed. The IP header must already be present in the -// original packet. The mtu is the maximum size of the packets. -func (e *endpoint) handleFragments(r *stack.Route, gso *stack.GSO, mtu uint32, pkt *stack.PacketBuffer, handler func(*stack.PacketBuffer) *tcpip.Error) (int, int, *tcpip.Error) { - fragMTU := int(calculateFragmentInnerMTU(mtu, pkt)) +// original packet. +func (e *endpoint) handleFragments(r *stack.Route, gso *stack.GSO, networkMTU uint32, pkt *stack.PacketBuffer, handler func(*stack.PacketBuffer) *tcpip.Error) (int, int, *tcpip.Error) { + // Round the MTU down to align to 8 bytes. + fragmentPayloadSize := networkMTU &^ 7 networkHeader := header.IPv4(pkt.NetworkHeader().View()) - pf := fragmentation.MakePacketFragmenter(pkt, fragMTU, pkt.AvailableHeaderBytes()+len(networkHeader)) + pf := fragmentation.MakePacketFragmenter(pkt, fragmentPayloadSize, pkt.AvailableHeaderBytes()+len(networkHeader)) var n int for { @@ -280,8 +281,14 @@ func (e *endpoint) writePacket(r *stack.Route, gso *stack.GSO, pkt *stack.Packet return nil } - if e.packetMustBeFragmented(pkt, gso) { - sent, remain, err := e.handleFragments(r, gso, e.nic.MTU(), pkt, func(fragPkt *stack.PacketBuffer) *tcpip.Error { + networkMTU, err := calculateNetworkMTU(e.nic.MTU(), uint32(pkt.NetworkHeader().View().Size())) + if err != nil { + r.Stats().IP.OutgoingPacketErrors.Increment() + return err + } + + if packetMustBeFragmented(pkt, networkMTU, gso) { + sent, remain, err := e.handleFragments(r, gso, networkMTU, pkt, func(fragPkt *stack.PacketBuffer) *tcpip.Error { // TODO(gvisor.dev/issue/3884): Evaluate whether we want to send each // fragment one by one using WritePacket() (current strategy) or if we // want to create a PacketBufferList from the fragments and feed it to @@ -292,6 +299,7 @@ func (e *endpoint) writePacket(r *stack.Route, gso *stack.GSO, pkt *stack.Packet r.Stats().IP.OutgoingPacketErrors.IncrementBy(uint64(remain)) return err } + if err := e.nic.WritePacket(r, gso, ProtocolNumber, pkt); err != nil { r.Stats().IP.OutgoingPacketErrors.Increment() return err @@ -311,17 +319,23 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe for pkt := pkts.Front(); pkt != nil; pkt = pkt.Next() { e.addIPHeader(r, pkt, params) - if e.packetMustBeFragmented(pkt, gso) { + networkMTU, err := calculateNetworkMTU(e.nic.MTU(), uint32(pkt.NetworkHeader().View().Size())) + if err != nil { + r.Stats().IP.OutgoingPacketErrors.IncrementBy(uint64(pkts.Len())) + return 0, err + } + + if packetMustBeFragmented(pkt, networkMTU, gso) { // Keep track of the packet that is about to be fragmented so it can be // removed once the fragmentation is done. originalPkt := pkt - if _, _, err := e.handleFragments(r, gso, e.nic.MTU(), pkt, func(fragPkt *stack.PacketBuffer) *tcpip.Error { + if _, _, err := e.handleFragments(r, gso, networkMTU, pkt, func(fragPkt *stack.PacketBuffer) *tcpip.Error { // Modify the packet list in place with the new fragments. pkts.InsertAfter(pkt, fragPkt) pkt = fragPkt return nil }); err != nil { - panic(fmt.Sprintf("e.handleFragments(_, _, %d, _, _) = %s", e.nic.MTU(), err)) + panic(fmt.Sprintf("e.handleFragments(_, _, %d, _, _) = %s", networkMTU, err)) } // Remove the packet that was just fragmented and process the rest. pkts.Remove(originalPkt) @@ -778,26 +792,32 @@ func (p *protocol) SetForwarding(v bool) { } } -// calculateMTU calculates the network-layer payload MTU based on the link-layer -// payload mtu. -func calculateMTU(mtu uint32) uint32 { - if mtu > MaxTotalSize { - mtu = MaxTotalSize +// calculateNetworkMTU calculates the network-layer payload MTU based on the +// link-layer payload mtu. +func calculateNetworkMTU(linkMTU, networkHeaderSize uint32) (uint32, *tcpip.Error) { + if linkMTU < header.IPv4MinimumMTU { + return 0, tcpip.ErrInvalidEndpointState } - return mtu - header.IPv4MinimumSize -} -// calculateFragmentInnerMTU calculates the maximum number of bytes of -// fragmentable data a fragment can have, based on the link layer mtu and pkt's -// network header size. -func calculateFragmentInnerMTU(mtu uint32, pkt *stack.PacketBuffer) uint32 { - if mtu > MaxTotalSize { - mtu = MaxTotalSize + // As per RFC 791 section 3.1, an IPv4 header cannot exceed 60 bytes in + // length: + // The maximal internet header is 60 octets, and a typical internet header + // is 20 octets, allowing a margin for headers of higher level protocols. + if networkHeaderSize > header.IPv4MaximumHeaderSize { + return 0, tcpip.ErrMalformedHeader } - mtu -= uint32(pkt.NetworkHeader().View().Size()) - // Round the MTU down to align to 8 bytes. - mtu &^= 7 - return mtu + + networkMTU := linkMTU + if networkMTU > MaxTotalSize { + networkMTU = MaxTotalSize + } + + return networkMTU - uint32(networkHeaderSize), nil +} + +func packetMustBeFragmented(pkt *stack.PacketBuffer, networkMTU uint32, gso *stack.GSO) bool { + payload := pkt.TransportHeader().View().Size() + pkt.Data.Size() + return (gso == nil || gso.Type == stack.GSONone) && uint32(payload) > networkMTU } // addressToUint32 translates an IPv4 address into its little endian uint32 |