From dffa4c66909f034429e933f204cd49655c3e224f Mon Sep 17 00:00:00 2001 From: Ghanan Gowripalan Date: Fri, 16 Oct 2020 13:51:55 -0700 Subject: Don't include link header when forwarding packets Before this change, if a link header was included in an incoming packet that is forwarded, the packet that gets sent out will take the original packet and add a link header to it while keeping the old link header. This would make the sent packet look like: OUTGOING LINK HDR | INCOMING LINK HDR | NETWORK HDR | ... Obviously this is incorrect as we should drop the incoming link header and only include the outgoing link header. This change fixes this bug. Test: integration_test.TestForwarding PiperOrigin-RevId: 337571447 --- pkg/tcpip/stack/nic.go | 5 +++-- pkg/tcpip/stack/packet_buffer.go | 20 +++++++++++++++++--- 2 files changed, 20 insertions(+), 5 deletions(-) (limited to 'pkg/tcpip/stack') diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go index 8828cc5fe..dcd4319bf 100644 --- a/pkg/tcpip/stack/nic.go +++ b/pkg/tcpip/stack/nic.go @@ -23,7 +23,6 @@ import ( "gvisor.dev/gvisor/pkg/sleep" "gvisor.dev/gvisor/pkg/sync" "gvisor.dev/gvisor/pkg/tcpip" - "gvisor.dev/gvisor/pkg/tcpip/buffer" "gvisor.dev/gvisor/pkg/tcpip/header" ) @@ -686,7 +685,9 @@ func (n *NIC) DeliverNetworkPacket(remote, local tcpip.LinkAddress, protocol tcp // packet to forward. fwdPkt := NewPacketBuffer(PacketBufferOptions{ ReserveHeaderBytes: int(n.LinkEndpoint.MaxHeaderLength()), - Data: buffer.NewVectorisedView(pkt.Size(), pkt.Views()), + // We need to do a deep copy of the IP packet because WritePacket (and + // friends) take ownership of the packet buffer, but we do not own it. + Data: PayloadSince(pkt.NetworkHeader()).ToVectorisedView(), }) // TODO(b/143425874) Decrease the TTL field in forwarded packets. diff --git a/pkg/tcpip/stack/packet_buffer.go b/pkg/tcpip/stack/packet_buffer.go index 105583c49..7f54a6de8 100644 --- a/pkg/tcpip/stack/packet_buffer.go +++ b/pkg/tcpip/stack/packet_buffer.go @@ -311,11 +311,25 @@ func (h PacketHeader) Consume(size int) (v buffer.View, consumed bool) { } // PayloadSince returns packet payload starting from and including a particular -// header. This method isn't optimized and should be used in test only. +// header. +// +// The returned View is owned by the caller - its backing buffer is separate +// from the packet header's underlying packet buffer. func PayloadSince(h PacketHeader) buffer.View { - var v buffer.View + size := h.pk.Data.Size() + for _, hinfo := range h.pk.headers[h.typ:] { + size += len(hinfo.buf) + } + + v := make(buffer.View, 0, size) + for _, hinfo := range h.pk.headers[h.typ:] { v = append(v, hinfo.buf...) } - return append(v, h.pk.Data.ToView()...) + + for _, view := range h.pk.Data.Views() { + v = append(v, view...) + } + + return v } -- cgit v1.2.3