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Diffstat (limited to 'pkg/tcpip/network/ipv4/ipv4.go')
-rw-r--r--pkg/tcpip/network/ipv4/ipv4.go188
1 files changed, 88 insertions, 100 deletions
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index 9ff27a363..3cd48ceb3 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -21,7 +21,6 @@
package ipv4
import (
- "fmt"
"sync/atomic"
"gvisor.dev/gvisor/pkg/tcpip"
@@ -127,14 +126,12 @@ func (e *endpoint) NetworkProtocolNumber() tcpip.NetworkProtocolNumber {
}
// writePacketFragments calls e.linkEP.WritePacket with each packet fragment to
-// write. It assumes that the IP header is entirely in pkt.Header but does not
-// assume that only the IP header is in pkt.Header. It assumes that the input
-// packet's stated length matches the length of the header+payload. mtu
-// includes the IP header and options. This does not support the DontFragment
-// IP flag.
+// write. It assumes that the IP header is already present in pkt.NetworkHeader.
+// pkt.TransportHeader may be set. mtu includes the IP header and options. This
+// does not support the DontFragment IP flag.
func (e *endpoint) writePacketFragments(r *stack.Route, gso *stack.GSO, mtu int, pkt *stack.PacketBuffer) *tcpip.Error {
// This packet is too big, it needs to be fragmented.
- ip := header.IPv4(pkt.Header.View())
+ ip := header.IPv4(pkt.NetworkHeader().View())
flags := ip.Flags()
// Update mtu to take into account the header, which will exist in all
@@ -148,88 +145,84 @@ func (e *endpoint) writePacketFragments(r *stack.Route, gso *stack.GSO, mtu int,
outerMTU := innerMTU + int(ip.HeaderLength())
offset := ip.FragmentOffset()
- originalAvailableLength := pkt.Header.AvailableLength()
+
+ // Keep the length reserved for link-layer, we need to create fragments with
+ // the same reserved length.
+ reservedForLink := pkt.AvailableHeaderBytes()
+
+ // Destroy the packet, pull all payloads out for fragmentation.
+ transHeader, data := pkt.TransportHeader().View(), pkt.Data
+
+ // Where possible, the first fragment that is sent has the same
+ // number of bytes reserved for header as the input packet. The link-layer
+ // endpoint may depend on this for looking at, eg, L4 headers.
+ transFitsFirst := len(transHeader) <= innerMTU
+
for i := 0; i < n; i++ {
- // Where possible, the first fragment that is sent has the same
- // pkt.Header.UsedLength() as the input packet. The link-layer
- // endpoint may depend on this for looking at, eg, L4 headers.
- h := ip
- if i > 0 {
- pkt.Header = buffer.NewPrependable(int(ip.HeaderLength()) + originalAvailableLength)
- h = header.IPv4(pkt.Header.Prepend(int(ip.HeaderLength())))
- copy(h, ip[:ip.HeaderLength()])
+ reserve := reservedForLink + int(ip.HeaderLength())
+ if i == 0 && transFitsFirst {
+ // Reserve for transport header if it's going to be put in the first
+ // fragment.
+ reserve += len(transHeader)
+ }
+ fragPkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
+ ReserveHeaderBytes: reserve,
+ })
+ fragPkt.NetworkProtocolNumber = header.IPv4ProtocolNumber
+
+ // Copy data for the fragment.
+ avail := innerMTU
+
+ if n := len(transHeader); n > 0 {
+ if n > avail {
+ n = avail
+ }
+ if i == 0 && transFitsFirst {
+ copy(fragPkt.TransportHeader().Push(n), transHeader)
+ } else {
+ fragPkt.Data.AppendView(transHeader[:n:n])
+ }
+ transHeader = transHeader[n:]
+ avail -= n
}
+
+ if avail > 0 {
+ n := data.Size()
+ if n > avail {
+ n = avail
+ }
+ data.ReadToVV(&fragPkt.Data, n)
+ avail -= n
+ }
+
+ copied := uint16(innerMTU - avail)
+
+ // Set lengths in header and calculate checksum.
+ h := header.IPv4(fragPkt.NetworkHeader().Push(len(ip)))
+ copy(h, ip)
if i != n-1 {
h.SetTotalLength(uint16(outerMTU))
h.SetFlagsFragmentOffset(flags|header.IPv4FlagMoreFragments, offset)
} else {
- h.SetTotalLength(uint16(h.HeaderLength()) + uint16(pkt.Data.Size()))
+ h.SetTotalLength(uint16(h.HeaderLength()) + copied)
h.SetFlagsFragmentOffset(flags, offset)
}
h.SetChecksum(0)
h.SetChecksum(^h.CalculateChecksum())
- offset += uint16(innerMTU)
- if i > 0 {
- newPayload := pkt.Data.Clone(nil)
- newPayload.CapLength(innerMTU)
- if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, &stack.PacketBuffer{
- Header: pkt.Header,
- Data: newPayload,
- NetworkHeader: buffer.View(h),
- NetworkProtocolNumber: header.IPv4ProtocolNumber,
- }); err != nil {
- return err
- }
- r.Stats().IP.PacketsSent.Increment()
- pkt.Data.TrimFront(newPayload.Size())
- continue
- }
- // Special handling for the first fragment because it comes
- // from the header.
- if outerMTU >= pkt.Header.UsedLength() {
- // This fragment can fit all of pkt.Header and possibly
- // some of pkt.Data, too.
- newPayload := pkt.Data.Clone(nil)
- newPayloadLength := outerMTU - pkt.Header.UsedLength()
- newPayload.CapLength(newPayloadLength)
- if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, &stack.PacketBuffer{
- Header: pkt.Header,
- Data: newPayload,
- NetworkHeader: buffer.View(h),
- NetworkProtocolNumber: header.IPv4ProtocolNumber,
- }); err != nil {
- return err
- }
- r.Stats().IP.PacketsSent.Increment()
- pkt.Data.TrimFront(newPayloadLength)
- } else {
- // The fragment is too small to fit all of pkt.Header.
- startOfHdr := pkt.Header
- startOfHdr.TrimBack(pkt.Header.UsedLength() - outerMTU)
- emptyVV := buffer.NewVectorisedView(0, []buffer.View{})
- if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, &stack.PacketBuffer{
- Header: startOfHdr,
- Data: emptyVV,
- NetworkHeader: buffer.View(h),
- NetworkProtocolNumber: header.IPv4ProtocolNumber,
- }); err != nil {
- return err
- }
- r.Stats().IP.PacketsSent.Increment()
- // Add the unused bytes of pkt.Header into the pkt.Data
- // that remains to be sent.
- restOfHdr := pkt.Header.View()[outerMTU:]
- tmp := buffer.NewVectorisedView(len(restOfHdr), []buffer.View{buffer.NewViewFromBytes(restOfHdr)})
- tmp.Append(pkt.Data)
- pkt.Data = tmp
+ offset += copied
+
+ // Send out the fragment.
+ if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, fragPkt); err != nil {
+ return err
}
+ r.Stats().IP.PacketsSent.Increment()
}
return nil
}
-func (e *endpoint) addIPHeader(r *stack.Route, hdr *buffer.Prependable, payloadSize int, params stack.NetworkHeaderParams) header.IPv4 {
- ip := header.IPv4(hdr.Prepend(header.IPv4MinimumSize))
- length := uint16(hdr.UsedLength() + payloadSize)
+func (e *endpoint) addIPHeader(r *stack.Route, pkt *stack.PacketBuffer, params stack.NetworkHeaderParams) {
+ ip := header.IPv4(pkt.NetworkHeader().Push(header.IPv4MinimumSize))
+ length := uint16(pkt.Size())
// RFC 6864 section 4.3 mandates uniqueness of ID values for non-atomic
// datagrams. Since the DF bit is never being set here, all datagrams
// are non-atomic and need an ID.
@@ -245,14 +238,12 @@ func (e *endpoint) addIPHeader(r *stack.Route, hdr *buffer.Prependable, payloadS
DstAddr: r.RemoteAddress,
})
ip.SetChecksum(^ip.CalculateChecksum())
- return ip
+ pkt.NetworkProtocolNumber = header.IPv4ProtocolNumber
}
// WritePacket writes a packet to the given destination address and protocol.
func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.NetworkHeaderParams, pkt *stack.PacketBuffer) *tcpip.Error {
- ip := e.addIPHeader(r, &pkt.Header, pkt.Data.Size(), params)
- pkt.NetworkHeader = buffer.View(ip)
- pkt.NetworkProtocolNumber = header.IPv4ProtocolNumber
+ e.addIPHeader(r, pkt, params)
// iptables filtering. All packets that reach here are locally
// generated.
@@ -269,7 +260,7 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
// only NATted packets, but removing this check short circuits broadcasts
// before they are sent out to other hosts.
if pkt.NatDone {
- netHeader := header.IPv4(pkt.NetworkHeader)
+ netHeader := header.IPv4(pkt.NetworkHeader().View())
ep, err := e.stack.FindNetworkEndpoint(header.IPv4ProtocolNumber, netHeader.DestinationAddress())
if err == nil {
route := r.ReverseRoute(netHeader.SourceAddress(), netHeader.DestinationAddress())
@@ -286,7 +277,7 @@ func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, params stack.Netw
if r.Loop&stack.PacketOut == 0 {
return nil
}
- if pkt.Header.UsedLength()+pkt.Data.Size() > int(e.linkEP.MTU()) && (gso == nil || gso.Type == stack.GSONone) {
+ if pkt.Size() > int(e.linkEP.MTU()) && (gso == nil || gso.Type == stack.GSONone) {
return e.writePacketFragments(r, gso, int(e.linkEP.MTU()), pkt)
}
if err := e.linkEP.WritePacket(r, gso, ProtocolNumber, pkt); err != nil {
@@ -306,9 +297,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
}
for pkt := pkts.Front(); pkt != nil; {
- ip := e.addIPHeader(r, &pkt.Header, pkt.Data.Size(), params)
- pkt.NetworkHeader = buffer.View(ip)
- pkt.NetworkProtocolNumber = header.IPv4ProtocolNumber
+ e.addIPHeader(r, pkt, params)
pkt = pkt.Next()
}
@@ -333,7 +322,7 @@ func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.Packe
continue
}
if _, ok := natPkts[pkt]; ok {
- netHeader := header.IPv4(pkt.NetworkHeader)
+ netHeader := header.IPv4(pkt.NetworkHeader().View())
if ep, err := e.stack.FindNetworkEndpoint(header.IPv4ProtocolNumber, netHeader.DestinationAddress()); err == nil {
src := netHeader.SourceAddress()
dst := netHeader.DestinationAddress()
@@ -402,17 +391,14 @@ func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBu
r.Stats().IP.PacketsSent.Increment()
- ip = ip[:ip.HeaderLength()]
- pkt.Header = buffer.NewPrependableFromView(buffer.View(ip))
- pkt.Data.TrimFront(int(ip.HeaderLength()))
return e.linkEP.WritePacket(r, nil /* gso */, ProtocolNumber, pkt)
}
// HandlePacket is called by the link layer when new ipv4 packets arrive for
// this endpoint.
func (e *endpoint) HandlePacket(r *stack.Route, pkt *stack.PacketBuffer) {
- h := header.IPv4(pkt.NetworkHeader)
- if !h.IsValid(pkt.Data.Size() + len(pkt.NetworkHeader) + len(pkt.TransportHeader)) {
+ h := header.IPv4(pkt.NetworkHeader().View())
+ if !h.IsValid(pkt.Data.Size() + pkt.NetworkHeader().View().Size() + pkt.TransportHeader().View().Size()) {
r.Stats().IP.MalformedPacketsReceived.Increment()
return
}
@@ -426,7 +412,7 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt *stack.PacketBuffer) {
}
if h.More() || h.FragmentOffset() != 0 {
- if pkt.Data.Size()+len(pkt.TransportHeader) == 0 {
+ if pkt.Data.Size()+pkt.TransportHeader().View().Size() == 0 {
// Drop the packet as it's marked as a fragment but has
// no payload.
r.Stats().IP.MalformedPacketsReceived.Increment()
@@ -470,7 +456,6 @@ func (e *endpoint) HandlePacket(r *stack.Route, pkt *stack.PacketBuffer) {
}
p := h.TransportProtocol()
if p == header.ICMPv4ProtocolNumber {
- pkt.NetworkHeader.CapLength(int(h.HeaderLength()))
e.handleICMP(r, pkt)
return
}
@@ -560,14 +545,19 @@ func (*protocol) Parse(pkt *stack.PacketBuffer) (proto tcpip.TransportProtocolNu
}
ipHdr := header.IPv4(hdr)
- // If there are options, pull those into hdr as well.
- if headerLen := int(ipHdr.HeaderLength()); headerLen > header.IPv4MinimumSize && headerLen <= pkt.Data.Size() {
- hdr, ok = pkt.Data.PullUp(headerLen)
- if !ok {
- panic(fmt.Sprintf("There are only %d bytes in pkt.Data, but there should be at least %d", pkt.Data.Size(), headerLen))
- }
- ipHdr = header.IPv4(hdr)
+ // Header may have options, determine the true header length.
+ headerLen := int(ipHdr.HeaderLength())
+ if headerLen < header.IPv4MinimumSize {
+ // TODO(gvisor.dev/issue/2404): Per RFC 791, IHL needs to be at least 5 in
+ // order for the packet to be valid. Figure out if we want to reject this
+ // case.
+ headerLen = header.IPv4MinimumSize
+ }
+ hdr, ok = pkt.NetworkHeader().Consume(headerLen)
+ if !ok {
+ return 0, false, false
}
+ ipHdr = header.IPv4(hdr)
// If this is a fragment, don't bother parsing the transport header.
parseTransportHeader := true
@@ -576,8 +566,6 @@ func (*protocol) Parse(pkt *stack.PacketBuffer) (proto tcpip.TransportProtocolNu
}
pkt.NetworkProtocolNumber = header.IPv4ProtocolNumber
- pkt.NetworkHeader = hdr
- pkt.Data.TrimFront(len(hdr))
pkt.Data.CapLength(int(ipHdr.TotalLength()) - len(hdr))
return ipHdr.TransportProtocol(), parseTransportHeader, true
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-07 17:53:59 +0000