Merge release-20201030.0-91-g6c0f53002 (automated)
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commit
4e9636928b
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@ -54,7 +54,7 @@ type IPv6Fields struct {
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// NextHeader is the "next header" field of an IPv6 packet.
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NextHeader uint8
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// HopLimit is the "hop limit" field of an IPv6 packet.
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// HopLimit is the "Hop Limit" field of an IPv6 packet.
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HopLimit uint8
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// SrcAddr is the "source ip address" of an IPv6 packet.
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@ -171,7 +171,7 @@ func (b IPv6) PayloadLength() uint16 {
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return binary.BigEndian.Uint16(b[IPv6PayloadLenOffset:])
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}
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// HopLimit returns the value of the "hop limit" field of the ipv6 header.
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// HopLimit returns the value of the "Hop Limit" field of the ipv6 header.
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func (b IPv6) HopLimit() uint8 {
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return b[hopLimit]
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}
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@ -236,6 +236,11 @@ func (b IPv6) SetDestinationAddress(addr tcpip.Address) {
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copy(b[v6DstAddr:][:IPv6AddressSize], addr)
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}
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// SetHopLimit sets the value of the "Hop Limit" field.
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func (b IPv6) SetHopLimit(v uint8) {
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b[hopLimit] = v
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}
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// SetNextHeader sets the value of the "next header" field of the ipv6 header.
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func (b IPv6) SetNextHeader(v uint8) {
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b[IPv6NextHeaderOffset] = v
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@ -290,6 +290,13 @@ type icmpReasonProtoUnreachable struct{}
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func (*icmpReasonProtoUnreachable) isICMPReason() {}
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// icmpReasonTTLExceeded is an error where a packet's time to live exceeded in
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// transit to its final destination, as per RFC 792 page 6, Time Exceeded
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// Message.
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type icmpReasonTTLExceeded struct{}
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func (*icmpReasonTTLExceeded) isICMPReason() {}
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// icmpReasonReassemblyTimeout is an error where insufficient fragments are
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// received to complete reassembly of a packet within a configured time after
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// the reception of the first-arriving fragment of that packet.
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@ -342,11 +349,31 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) *tcpi
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return nil
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}
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// If we hit a TTL Exceeded error, then we know we are operating as a router.
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// As per RFC 792 page 6, Time Exceeded Message,
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//
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// If the gateway processing a datagram finds the time to live field
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// is zero it must discard the datagram. The gateway may also notify
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// the source host via the time exceeded message.
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//
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// ...
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//
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// Code 0 may be received from a gateway. ...
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//
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// Note, Code 0 is the TTL exceeded error.
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//
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// If we are operating as a router/gateway, don't use the packet's destination
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// address as the response's source address as we should not not own the
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// destination address of a packet we are forwarding.
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localAddr := origIPHdrDst
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if _, ok := reason.(*icmpReasonTTLExceeded); ok {
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localAddr = ""
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}
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// Even if we were able to receive a packet from some remote, we may not have
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// a route to it - the remote may be blocked via routing rules. We must always
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// consult our routing table and find a route to the remote before sending any
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// packet.
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route, err := p.stack.FindRoute(pkt.NICID, origIPHdrDst, origIPHdrSrc, ProtocolNumber, false /* multicastLoop */)
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route, err := p.stack.FindRoute(pkt.NICID, localAddr, origIPHdrSrc, ProtocolNumber, false /* multicastLoop */)
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if err != nil {
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return err
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}
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@ -454,6 +481,10 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) *tcpi
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icmpHdr.SetType(header.ICMPv4DstUnreachable)
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icmpHdr.SetCode(header.ICMPv4ProtoUnreachable)
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counter = sent.DstUnreachable
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case *icmpReasonTTLExceeded:
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icmpHdr.SetType(header.ICMPv4TimeExceeded)
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icmpHdr.SetCode(header.ICMPv4TTLExceeded)
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counter = sent.TimeExceeded
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case *icmpReasonReassemblyTimeout:
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icmpHdr.SetType(header.ICMPv4TimeExceeded)
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icmpHdr.SetCode(header.ICMPv4ReassemblyTimeout)
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@ -485,6 +485,16 @@ func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBu
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// forwardPacket attempts to forward a packet to its final destination.
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func (e *endpoint) forwardPacket(pkt *stack.PacketBuffer) *tcpip.Error {
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h := header.IPv4(pkt.NetworkHeader().View())
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ttl := h.TTL()
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if ttl == 0 {
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// As per RFC 792 page 6, Time Exceeded Message,
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//
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// If the gateway processing a datagram finds the time to live field
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// is zero it must discard the datagram. The gateway may also notify
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// the source host via the time exceeded message.
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return e.protocol.returnError(&icmpReasonTTLExceeded{}, pkt)
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}
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dstAddr := h.DestinationAddress()
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// Check if the destination is owned by the stack.
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@ -503,13 +513,22 @@ func (e *endpoint) forwardPacket(pkt *stack.PacketBuffer) *tcpip.Error {
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}
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defer r.Release()
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// TODO(b/143425874) Decrease the TTL field in forwarded packets.
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// We need to do a deep copy of the IP packet because
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// WriteHeaderIncludedPacket takes ownership of the packet buffer, but we do
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// not own it.
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newHdr := header.IPv4(stack.PayloadSince(pkt.NetworkHeader()))
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// As per RFC 791 page 30, Time to Live,
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//
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// This field must be decreased at each point that the internet header
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// is processed to reflect the time spent processing the datagram.
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// Even if no local information is available on the time actually
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// spent, the field must be decremented by 1.
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newHdr.SetTTL(ttl - 1)
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return r.WriteHeaderIncludedPacket(stack.NewPacketBuffer(stack.PacketBufferOptions{
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ReserveHeaderBytes: int(r.MaxHeaderLength()),
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// We need to do a deep copy of the IP packet because
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// WriteHeaderIncludedPacket takes ownership of the packet buffer, but we do
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// not own it.
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Data: stack.PayloadSince(pkt.NetworkHeader()).ToVectorisedView(),
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Data: buffer.View(newHdr).ToVectorisedView(),
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}))
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}
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@ -750,6 +750,12 @@ type icmpReasonPortUnreachable struct{}
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func (*icmpReasonPortUnreachable) isICMPReason() {}
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// icmpReasonHopLimitExceeded is an error where a packet's hop limit exceeded in
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// transit to its final destination, as per RFC 4443 section 3.3.
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type icmpReasonHopLimitExceeded struct{}
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func (*icmpReasonHopLimitExceeded) isICMPReason() {}
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// icmpReasonReassemblyTimeout is an error where insufficient fragments are
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// received to complete reassembly of a packet within a configured time after
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// the reception of the first-arriving fragment of that packet.
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@ -794,11 +800,27 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) *tcpi
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return nil
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}
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// If we hit a Hop Limit Exceeded error, then we know we are operating as a
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// router. As per RFC 4443 section 3.3:
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//
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// If a router receives a packet with a Hop Limit of zero, or if a
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// router decrements a packet's Hop Limit to zero, it MUST discard the
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// packet and originate an ICMPv6 Time Exceeded message with Code 0 to
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// the source of the packet. This indicates either a routing loop or
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// too small an initial Hop Limit value.
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//
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// If we are operating as a router, do not use the packet's destination
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// address as the response's source address as we should not own the
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// destination address of a packet we are forwarding.
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localAddr := origIPHdrDst
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if _, ok := reason.(*icmpReasonHopLimitExceeded); ok {
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localAddr = ""
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}
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// Even if we were able to receive a packet from some remote, we may not have
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// a route to it - the remote may be blocked via routing rules. We must always
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// consult our routing table and find a route to the remote before sending any
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// packet.
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route, err := p.stack.FindRoute(pkt.NICID, origIPHdrDst, origIPHdrSrc, ProtocolNumber, false /* multicastLoop */)
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route, err := p.stack.FindRoute(pkt.NICID, localAddr, origIPHdrSrc, ProtocolNumber, false /* multicastLoop */)
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if err != nil {
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return err
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}
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@ -811,8 +833,6 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) *tcpi
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return nil
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}
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network, transport := pkt.NetworkHeader().View(), pkt.TransportHeader().View()
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if pkt.TransportProtocolNumber == header.ICMPv6ProtocolNumber {
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// TODO(gvisor.dev/issues/3810): Sort this out when ICMP headers are stored.
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// Unfortunately at this time ICMP Packets do not have a transport
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@ -830,6 +850,8 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) *tcpi
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}
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}
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network, transport := pkt.NetworkHeader().View(), pkt.TransportHeader().View()
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// As per RFC 4443 section 2.4
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//
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// (c) Every ICMPv6 error message (type < 128) MUST include
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@ -873,6 +895,10 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) *tcpi
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icmpHdr.SetType(header.ICMPv6DstUnreachable)
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icmpHdr.SetCode(header.ICMPv6PortUnreachable)
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counter = sent.DstUnreachable
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case *icmpReasonHopLimitExceeded:
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icmpHdr.SetType(header.ICMPv6TimeExceeded)
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icmpHdr.SetCode(header.ICMPv6HopLimitExceeded)
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counter = sent.TimeExceeded
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case *icmpReasonReassemblyTimeout:
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icmpHdr.SetType(header.ICMPv6TimeExceeded)
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icmpHdr.SetCode(header.ICMPv6ReassemblyTimeout)
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@ -645,6 +645,18 @@ func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBu
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// forwardPacket attempts to forward a packet to its final destination.
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func (e *endpoint) forwardPacket(pkt *stack.PacketBuffer) *tcpip.Error {
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h := header.IPv6(pkt.NetworkHeader().View())
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hopLimit := h.HopLimit()
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if hopLimit <= 1 {
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// As per RFC 4443 section 3.3,
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//
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// If a router receives a packet with a Hop Limit of zero, or if a
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// router decrements a packet's Hop Limit to zero, it MUST discard the
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// packet and originate an ICMPv6 Time Exceeded message with Code 0 to
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// the source of the packet. This indicates either a routing loop or
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// too small an initial Hop Limit value.
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return e.protocol.returnError(&icmpReasonHopLimitExceeded{}, pkt)
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}
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dstAddr := h.DestinationAddress()
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// Check if the destination is owned by the stack.
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@ -663,13 +675,20 @@ func (e *endpoint) forwardPacket(pkt *stack.PacketBuffer) *tcpip.Error {
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}
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defer r.Release()
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// TODO(b/143425874) Decrease the TTL field in forwarded packets.
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// We need to do a deep copy of the IP packet because
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// WriteHeaderIncludedPacket takes ownership of the packet buffer, but we do
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// not own it.
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newHdr := header.IPv6(stack.PayloadSince(pkt.NetworkHeader()))
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// As per RFC 8200 section 3,
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//
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// Hop Limit 8-bit unsigned integer. Decremented by 1 by
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// each node that forwards the packet.
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newHdr.SetHopLimit(hopLimit - 1)
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return r.WriteHeaderIncludedPacket(stack.NewPacketBuffer(stack.PacketBufferOptions{
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ReserveHeaderBytes: int(r.MaxHeaderLength()),
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// We need to do a deep copy of the IP packet because
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// WriteHeaderIncludedPacket takes ownership of the packet buffer, but we do
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// not own it.
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Data: stack.PayloadSince(pkt.NetworkHeader()).ToVectorisedView(),
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Data: buffer.View(newHdr).ToVectorisedView(),
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}))
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}
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