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-rw-r--r--pkg/tcpip/network/ipv6/icmp.go7
-rw-r--r--pkg/tcpip/network/ipv6/ipv6.go112
-rw-r--r--pkg/tcpip/network/ipv6/ipv6_test.go43
3 files changed, 108 insertions, 54 deletions
diff --git a/pkg/tcpip/network/ipv6/icmp.go b/pkg/tcpip/network/ipv6/icmp.go
index ead6bedcb..40908ddaa 100644
--- a/pkg/tcpip/network/ipv6/icmp.go
+++ b/pkg/tcpip/network/ipv6/icmp.go
@@ -170,8 +170,11 @@ func (e *endpoint) handleICMP(r *stack.Route, pkt *stack.PacketBuffer, hasFragme
return
}
pkt.Data.TrimFront(header.ICMPv6PacketTooBigMinimumSize)
- mtu := header.ICMPv6(hdr).MTU()
- e.handleControl(stack.ControlPacketTooBig, calculateMTU(mtu), pkt)
+ networkMTU, err := calculateNetworkMTU(header.ICMPv6(hdr).MTU(), header.IPv6MinimumSize)
+ if err != nil {
+ networkMTU = 0
+ }
+ e.handleControl(stack.ControlPacketTooBig, networkMTU, pkt)
case header.ICMPv6DstUnreachable:
received.DstUnreachable.Increment()
diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go
index 9670696c7..3c2578343 100644
--- a/pkg/tcpip/network/ipv6/ipv6.go
+++ b/pkg/tcpip/network/ipv6/ipv6.go
@@ -46,7 +46,7 @@ const (
// ProtocolNumber is the ipv6 protocol number.
ProtocolNumber = header.IPv6ProtocolNumber
- // maxTotalSize is maximum size that can be encoded in the 16-bit
+ // maxPayloadSize is the maximum size that can be encoded in the 16-bit
// PayloadLength field of the ipv6 header.
maxPayloadSize = 0xffff
@@ -363,7 +363,11 @@ 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.IPv6MinimumSize)
+ if err != nil {
+ return 0
+ }
+ return networkMTU
}
// MaxHeaderLength returns the maximum length needed by ipv6 headers (and
@@ -386,27 +390,40 @@ 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())
+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
}
// 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. The transport
-// header protocol number is required to avoid parsing the IPv6 extension
-// headers.
-func (e *endpoint) handleFragments(r *stack.Route, gso *stack.GSO, mtu uint32, pkt *stack.PacketBuffer, transProto tcpip.TransportProtocolNumber, handler func(*stack.PacketBuffer) *tcpip.Error) (int, int, *tcpip.Error) {
- fragMTU := int(calculateFragmentInnerMTU(mtu, pkt))
- if fragMTU < pkt.TransportHeader().View().Size() {
+// original packet. The transport header protocol number is required to avoid
+// parsing the IPv6 extension headers.
+func (e *endpoint) handleFragments(r *stack.Route, gso *stack.GSO, networkMTU uint32, pkt *stack.PacketBuffer, transProto tcpip.TransportProtocolNumber, handler func(*stack.PacketBuffer) *tcpip.Error) (int, int, *tcpip.Error) {
+ networkHeader := header.IPv6(pkt.NetworkHeader().View())
+
+ // TODO(gvisor.dev/issue/3912): Once the Authentication or ESP Headers are
+ // supported for outbound packets, their length should not affect the fragment
+ // maximum payload length because they should only be transmitted once.
+ fragmentPayloadLen := (networkMTU - header.IPv6FragmentHeaderSize) &^ 7
+ if fragmentPayloadLen < header.IPv6FragmentExtHdrFragmentOffsetBytesPerUnit {
+ // We need at least 8 bytes of space left for the fragmentable part because
+ // the fragment payload must obviously be non-zero and must be a multiple
+ // of 8 as per RFC 8200 section 4.5:
+ // Each complete fragment, except possibly the last ("rightmost") one, is
+ // an integer multiple of 8 octets long.
+ return 0, 1, tcpip.ErrMessageTooLong
+ }
+
+ if fragmentPayloadLen < uint32(pkt.TransportHeader().View().Size()) {
// As per RFC 8200 Section 4.5, the Transport Header is expected to be small
// enough to fit in the first fragment.
return 0, 1, tcpip.ErrMessageTooLong
}
- pf := fragmentation.MakePacketFragmenter(pkt, fragMTU, calculateFragmentReserve(pkt))
+ pf := fragmentation.MakePacketFragmenter(pkt, fragmentPayloadLen, calculateFragmentReserve(pkt))
id := atomic.AddUint32(&e.protocol.ids[hashRoute(r, e.protocol.hashIV)%buckets], 1)
- networkHeader := header.IPv6(pkt.NetworkHeader().View())
var n int
for {
@@ -468,8 +485,14 @@ 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, protocol, 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, protocol, 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
@@ -499,13 +522,20 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
return pkts.Len(), nil
}
+ linkMTU := e.nic.MTU()
for pb := pkts.Front(); pb != nil; pb = pb.Next() {
e.addIPHeader(r, pb, params)
- if e.packetMustBeFragmented(pb, gso) {
+
+ networkMTU, err := calculateNetworkMTU(linkMTU, uint32(pb.NetworkHeader().View().Size()))
+ if err != nil {
+ r.Stats().IP.OutgoingPacketErrors.IncrementBy(uint64(pkts.Len()))
+ return 0, err
+ }
+ if packetMustBeFragmented(pb, networkMTU, gso) {
// Keep track of the packet that is about to be fragmented so it can be
// removed once the fragmentation is done.
originalPkt := pb
- if _, _, err := e.handleFragments(r, gso, e.nic.MTU(), pb, params.Protocol, func(fragPkt *stack.PacketBuffer) *tcpip.Error {
+ if _, _, err := e.handleFragments(r, gso, networkMTU, pb, params.Protocol, func(fragPkt *stack.PacketBuffer) *tcpip.Error {
// Modify the packet list in place with the new fragments.
pkts.InsertAfter(pb, fragPkt)
pb = fragPkt
@@ -569,7 +599,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
return n + len(dropped), nil
}
-// WriteHeaderIncludedPacker implements stack.NetworkEndpoint.
+// WriteHeaderIncludedPacket implements stack.NetworkEndpoint.
func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBuffer) *tcpip.Error {
// The packet already has an IP header, but there are a few required checks.
h, ok := pkt.Data.PullUp(header.IPv6MinimumSize)
@@ -1427,14 +1457,31 @@ 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 {
- mtu -= header.IPv6MinimumSize
- if mtu <= maxPayloadSize {
- return mtu
+// calculateNetworkMTU calculates the network-layer payload MTU based on the
+// link-layer payload MTU and the length of every IPv6 header.
+// Note that this is different than the Payload Length field of the IPv6 header,
+// which includes the length of the extension headers.
+func calculateNetworkMTU(linkMTU, networkHeadersLen uint32) (uint32, *tcpip.Error) {
+ if linkMTU < header.IPv6MinimumMTU {
+ return 0, tcpip.ErrInvalidEndpointState
+ }
+
+ // As per RFC 7112 section 5, we should discard packets if their IPv6 header
+ // is bigger than 1280 bytes (ie, the minimum link MTU) since we do not
+ // support PMTU discovery:
+ // Hosts that do not discover the Path MTU MUST limit the IPv6 Header Chain
+ // length to 1280 bytes. Limiting the IPv6 Header Chain length to 1280
+ // bytes ensures that the header chain length does not exceed the IPv6
+ // minimum MTU.
+ if networkHeadersLen > header.IPv6MinimumMTU {
+ return 0, tcpip.ErrMalformedHeader
}
- return maxPayloadSize
+
+ networkMTU := linkMTU - uint32(networkHeadersLen)
+ if networkMTU > maxPayloadSize {
+ networkMTU = maxPayloadSize
+ }
+ return networkMTU, nil
}
// Options holds options to configure a new protocol.
@@ -1509,23 +1556,6 @@ func NewProtocol(s *stack.Stack) stack.NetworkProtocol {
return NewProtocolWithOptions(Options{})(s)
}
-// 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 {
- // TODO(gvisor.dev/issue/3912): Once the Authentication or ESP Headers are
- // supported for outbound packets, their length should not affect the fragment
- // MTU because they should only be transmitted once.
- mtu -= uint32(pkt.NetworkHeader().View().Size())
- mtu -= header.IPv6FragmentHeaderSize
- // Round the MTU down to align to 8 bytes.
- mtu &^= 7
- if mtu <= maxPayloadSize {
- return mtu
- }
- return maxPayloadSize
-}
-
func calculateFragmentReserve(pkt *stack.PacketBuffer) int {
return pkt.AvailableHeaderBytes() + pkt.NetworkHeader().View().Size() + header.IPv6FragmentHeaderSize
}
diff --git a/pkg/tcpip/network/ipv6/ipv6_test.go b/pkg/tcpip/network/ipv6/ipv6_test.go
index 297868f24..dc4200b8a 100644
--- a/pkg/tcpip/network/ipv6/ipv6_test.go
+++ b/pkg/tcpip/network/ipv6/ipv6_test.go
@@ -238,7 +238,7 @@ func TestReceiveOnAllNodesMulticastAddr(t *testing.T) {
NetworkProtocols: []stack.NetworkProtocolFactory{NewProtocol},
TransportProtocols: []stack.TransportProtocolFactory{test.protocolFactory},
})
- e := channel.New(10, 1280, linkAddr1)
+ e := channel.New(10, header.IPv6MinimumMTU, linkAddr1)
if err := s.CreateNIC(1, e); err != nil {
t.Fatalf("CreateNIC(_) = %s", err)
}
@@ -271,7 +271,7 @@ func TestReceiveOnSolicitedNodeAddr(t *testing.T) {
NetworkProtocols: []stack.NetworkProtocolFactory{NewProtocol},
TransportProtocols: []stack.TransportProtocolFactory{test.protocolFactory},
})
- e := channel.New(1, 1280, linkAddr1)
+ e := channel.New(1, header.IPv6MinimumMTU, linkAddr1)
if err := s.CreateNIC(nicID, e); err != nil {
t.Fatalf("CreateNIC(%d, _) = %s", nicID, err)
}
@@ -825,7 +825,7 @@ func TestReceiveIPv6ExtHdrs(t *testing.T) {
NetworkProtocols: []stack.NetworkProtocolFactory{NewProtocol},
TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol},
})
- e := channel.New(1, 1280, linkAddr1)
+ e := channel.New(1, header.IPv6MinimumMTU, linkAddr1)
if err := s.CreateNIC(nicID, e); err != nil {
t.Fatalf("CreateNIC(%d, _) = %s", nicID, err)
}
@@ -1844,7 +1844,7 @@ func TestReceiveIPv6Fragments(t *testing.T) {
NetworkProtocols: []stack.NetworkProtocolFactory{NewProtocol},
TransportProtocols: []stack.TransportProtocolFactory{udp.NewProtocol},
})
- e := channel.New(0, 1280, linkAddr1)
+ e := channel.New(0, header.IPv6MinimumMTU, linkAddr1)
if err := s.CreateNIC(nicID, e); err != nil {
t.Fatalf("CreateNIC(%d, _) = %s", nicID, err)
}
@@ -2230,8 +2230,8 @@ var fragmentationTests = []struct {
wantFragments []fragmentInfo
}{
{
- description: "No Fragmentation",
- mtu: 1280,
+ description: "No fragmentation",
+ mtu: header.IPv6MinimumMTU,
gso: nil,
transHdrLen: 0,
payloadSize: 1000,
@@ -2241,7 +2241,18 @@ var fragmentationTests = []struct {
},
{
description: "Fragmented",
- mtu: 1280,
+ mtu: header.IPv6MinimumMTU,
+ gso: nil,
+ transHdrLen: 0,
+ payloadSize: 2000,
+ wantFragments: []fragmentInfo{
+ {offset: 0, payloadSize: 1240, more: true},
+ {offset: 154, payloadSize: 776, more: false},
+ },
+ },
+ {
+ description: "Fragmented with mtu not a multiple of 8",
+ mtu: header.IPv6MinimumMTU + 1,
gso: nil,
transHdrLen: 0,
payloadSize: 2000,
@@ -2262,7 +2273,7 @@ var fragmentationTests = []struct {
},
{
description: "Fragmented with gso none",
- mtu: 1280,
+ mtu: header.IPv6MinimumMTU,
gso: &stack.GSO{Type: stack.GSONone},
transHdrLen: 0,
payloadSize: 1400,
@@ -2273,7 +2284,7 @@ var fragmentationTests = []struct {
},
{
description: "Fragmented with big header",
- mtu: 1280,
+ mtu: header.IPv6MinimumMTU,
gso: nil,
transHdrLen: 100,
payloadSize: 1200,
@@ -2448,8 +2459,8 @@ func TestFragmentationErrors(t *testing.T) {
wantError: tcpip.ErrAborted,
},
{
- description: "Error on packet with MTU smaller than transport header",
- mtu: 1280,
+ description: "Error when MTU is smaller than transport header",
+ mtu: header.IPv6MinimumMTU,
transHdrLen: 1500,
payloadSize: 500,
allowPackets: 0,
@@ -2457,6 +2468,16 @@ func TestFragmentationErrors(t *testing.T) {
mockError: nil,
wantError: tcpip.ErrMessageTooLong,
},
+ {
+ description: "Error when MTU is smaller than IPv6 minimum MTU",
+ mtu: header.IPv6MinimumMTU - 1,
+ transHdrLen: 0,
+ payloadSize: 500,
+ allowPackets: 0,
+ outgoingErrors: 1,
+ mockError: nil,
+ wantError: tcpip.ErrInvalidEndpointState,
+ },
}
for _, ft := range tests {
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-16 06:34:26 +0000