summaryrefslogtreecommitdiffhomepage
path: root/pkg/tcpip/network
diff options
context:
space:
mode:
Diffstat (limited to 'pkg/tcpip/network')
-rw-r--r--pkg/tcpip/network/ipv4/icmp.go33
-rw-r--r--pkg/tcpip/network/ipv4/ipv4.go29
-rw-r--r--pkg/tcpip/network/ipv6/icmp.go32
-rw-r--r--pkg/tcpip/network/ipv6/ipv6.go29
4 files changed, 109 insertions, 14 deletions
diff --git a/pkg/tcpip/network/ipv4/icmp.go b/pkg/tcpip/network/ipv4/icmp.go
index 9b5e37fee..58a19e74a 100644
--- a/pkg/tcpip/network/ipv4/icmp.go
+++ b/pkg/tcpip/network/ipv4/icmp.go
@@ -290,6 +290,13 @@ type icmpReasonProtoUnreachable struct{}
func (*icmpReasonProtoUnreachable) isICMPReason() {}
+// icmpReasonTTLExceeded is an error where a packet's time to live exceeded in
+// transit to its final destination, as per RFC 792 page 6, Time Exceeded
+// Message.
+type icmpReasonTTLExceeded struct{}
+
+func (*icmpReasonTTLExceeded) isICMPReason() {}
+
// icmpReasonReassemblyTimeout is an error where insufficient fragments are
// received to complete reassembly of a packet within a configured time after
// the reception of the first-arriving fragment of that packet.
@@ -342,11 +349,31 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) *tcpi
return nil
}
+ // If we hit a TTL Exceeded error, then we know we are operating as a router.
+ // As per RFC 792 page 6, Time Exceeded Message,
+ //
+ // If the gateway processing a datagram finds the time to live field
+ // is zero it must discard the datagram. The gateway may also notify
+ // the source host via the time exceeded message.
+ //
+ // ...
+ //
+ // Code 0 may be received from a gateway. ...
+ //
+ // Note, Code 0 is the TTL exceeded error.
+ //
+ // If we are operating as a router/gateway, don't use the packet's destination
+ // address as the response's source address as we should not not own the
+ // destination address of a packet we are forwarding.
+ localAddr := origIPHdrDst
+ if _, ok := reason.(*icmpReasonTTLExceeded); ok {
+ localAddr = ""
+ }
// Even if we were able to receive a packet from some remote, we may not have
// a route to it - the remote may be blocked via routing rules. We must always
// consult our routing table and find a route to the remote before sending any
// packet.
- route, err := p.stack.FindRoute(pkt.NICID, origIPHdrDst, origIPHdrSrc, ProtocolNumber, false /* multicastLoop */)
+ route, err := p.stack.FindRoute(pkt.NICID, localAddr, origIPHdrSrc, ProtocolNumber, false /* multicastLoop */)
if err != nil {
return err
}
@@ -454,6 +481,10 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) *tcpi
icmpHdr.SetType(header.ICMPv4DstUnreachable)
icmpHdr.SetCode(header.ICMPv4ProtoUnreachable)
counter = sent.DstUnreachable
+ case *icmpReasonTTLExceeded:
+ icmpHdr.SetType(header.ICMPv4TimeExceeded)
+ icmpHdr.SetCode(header.ICMPv4TTLExceeded)
+ counter = sent.TimeExceeded
case *icmpReasonReassemblyTimeout:
icmpHdr.SetType(header.ICMPv4TimeExceeded)
icmpHdr.SetCode(header.ICMPv4ReassemblyTimeout)
diff --git a/pkg/tcpip/network/ipv4/ipv4.go b/pkg/tcpip/network/ipv4/ipv4.go
index 0c828004a..b4f21d61e 100644
--- a/pkg/tcpip/network/ipv4/ipv4.go
+++ b/pkg/tcpip/network/ipv4/ipv4.go
@@ -485,6 +485,16 @@ func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBu
// forwardPacket attempts to forward a packet to its final destination.
func (e *endpoint) forwardPacket(pkt *stack.PacketBuffer) *tcpip.Error {
h := header.IPv4(pkt.NetworkHeader().View())
+ ttl := h.TTL()
+ if ttl == 0 {
+ // As per RFC 792 page 6, Time Exceeded Message,
+ //
+ // If the gateway processing a datagram finds the time to live field
+ // is zero it must discard the datagram. The gateway may also notify
+ // the source host via the time exceeded message.
+ return e.protocol.returnError(&icmpReasonTTLExceeded{}, pkt)
+ }
+
dstAddr := h.DestinationAddress()
// Check if the destination is owned by the stack.
@@ -503,13 +513,22 @@ func (e *endpoint) forwardPacket(pkt *stack.PacketBuffer) *tcpip.Error {
}
defer r.Release()
- // TODO(b/143425874) Decrease the TTL field in forwarded packets.
+ // We need to do a deep copy of the IP packet because
+ // WriteHeaderIncludedPacket takes ownership of the packet buffer, but we do
+ // not own it.
+ newHdr := header.IPv4(stack.PayloadSince(pkt.NetworkHeader()))
+
+ // As per RFC 791 page 30, Time to Live,
+ //
+ // This field must be decreased at each point that the internet header
+ // is processed to reflect the time spent processing the datagram.
+ // Even if no local information is available on the time actually
+ // spent, the field must be decremented by 1.
+ newHdr.SetTTL(ttl - 1)
+
return r.WriteHeaderIncludedPacket(stack.NewPacketBuffer(stack.PacketBufferOptions{
ReserveHeaderBytes: int(r.MaxHeaderLength()),
- // We need to do a deep copy of the IP packet because
- // WriteHeaderIncludedPacket takes ownership of the packet buffer, but we do
- // not own it.
- Data: stack.PayloadSince(pkt.NetworkHeader()).ToVectorisedView(),
+ Data: buffer.View(newHdr).ToVectorisedView(),
}))
}
diff --git a/pkg/tcpip/network/ipv6/icmp.go b/pkg/tcpip/network/ipv6/icmp.go
index 8502b848c..8d788af80 100644
--- a/pkg/tcpip/network/ipv6/icmp.go
+++ b/pkg/tcpip/network/ipv6/icmp.go
@@ -750,6 +750,12 @@ type icmpReasonPortUnreachable struct{}
func (*icmpReasonPortUnreachable) isICMPReason() {}
+// icmpReasonHopLimitExceeded is an error where a packet's hop limit exceeded in
+// transit to its final destination, as per RFC 4443 section 3.3.
+type icmpReasonHopLimitExceeded struct{}
+
+func (*icmpReasonHopLimitExceeded) isICMPReason() {}
+
// icmpReasonReassemblyTimeout is an error where insufficient fragments are
// received to complete reassembly of a packet within a configured time after
// the reception of the first-arriving fragment of that packet.
@@ -794,11 +800,27 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) *tcpi
return nil
}
+ // If we hit a Hop Limit Exceeded error, then we know we are operating as a
+ // router. As per RFC 4443 section 3.3:
+ //
+ // If a router receives a packet with a Hop Limit of zero, or if a
+ // router decrements a packet's Hop Limit to zero, it MUST discard the
+ // packet and originate an ICMPv6 Time Exceeded message with Code 0 to
+ // the source of the packet. This indicates either a routing loop or
+ // too small an initial Hop Limit value.
+ //
+ // If we are operating as a router, do not use the packet's destination
+ // address as the response's source address as we should not own the
+ // destination address of a packet we are forwarding.
+ localAddr := origIPHdrDst
+ if _, ok := reason.(*icmpReasonHopLimitExceeded); ok {
+ localAddr = ""
+ }
// Even if we were able to receive a packet from some remote, we may not have
// a route to it - the remote may be blocked via routing rules. We must always
// consult our routing table and find a route to the remote before sending any
// packet.
- route, err := p.stack.FindRoute(pkt.NICID, origIPHdrDst, origIPHdrSrc, ProtocolNumber, false /* multicastLoop */)
+ route, err := p.stack.FindRoute(pkt.NICID, localAddr, origIPHdrSrc, ProtocolNumber, false /* multicastLoop */)
if err != nil {
return err
}
@@ -811,8 +833,6 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) *tcpi
return nil
}
- network, transport := pkt.NetworkHeader().View(), pkt.TransportHeader().View()
-
if pkt.TransportProtocolNumber == header.ICMPv6ProtocolNumber {
// TODO(gvisor.dev/issues/3810): Sort this out when ICMP headers are stored.
// Unfortunately at this time ICMP Packets do not have a transport
@@ -830,6 +850,8 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) *tcpi
}
}
+ network, transport := pkt.NetworkHeader().View(), pkt.TransportHeader().View()
+
// As per RFC 4443 section 2.4
//
// (c) Every ICMPv6 error message (type < 128) MUST include
@@ -873,6 +895,10 @@ func (p *protocol) returnError(reason icmpReason, pkt *stack.PacketBuffer) *tcpi
icmpHdr.SetType(header.ICMPv6DstUnreachable)
icmpHdr.SetCode(header.ICMPv6PortUnreachable)
counter = sent.DstUnreachable
+ case *icmpReasonHopLimitExceeded:
+ icmpHdr.SetType(header.ICMPv6TimeExceeded)
+ icmpHdr.SetCode(header.ICMPv6HopLimitExceeded)
+ counter = sent.TimeExceeded
case *icmpReasonReassemblyTimeout:
icmpHdr.SetType(header.ICMPv6TimeExceeded)
icmpHdr.SetCode(header.ICMPv6ReassemblyTimeout)
diff --git a/pkg/tcpip/network/ipv6/ipv6.go b/pkg/tcpip/network/ipv6/ipv6.go
index 38a0633bd..7697ff987 100644
--- a/pkg/tcpip/network/ipv6/ipv6.go
+++ b/pkg/tcpip/network/ipv6/ipv6.go
@@ -645,6 +645,18 @@ func (e *endpoint) WriteHeaderIncludedPacket(r *stack.Route, pkt *stack.PacketBu
// forwardPacket attempts to forward a packet to its final destination.
func (e *endpoint) forwardPacket(pkt *stack.PacketBuffer) *tcpip.Error {
h := header.IPv6(pkt.NetworkHeader().View())
+ hopLimit := h.HopLimit()
+ if hopLimit <= 1 {
+ // As per RFC 4443 section 3.3,
+ //
+ // If a router receives a packet with a Hop Limit of zero, or if a
+ // router decrements a packet's Hop Limit to zero, it MUST discard the
+ // packet and originate an ICMPv6 Time Exceeded message with Code 0 to
+ // the source of the packet. This indicates either a routing loop or
+ // too small an initial Hop Limit value.
+ return e.protocol.returnError(&icmpReasonHopLimitExceeded{}, pkt)
+ }
+
dstAddr := h.DestinationAddress()
// Check if the destination is owned by the stack.
@@ -663,13 +675,20 @@ func (e *endpoint) forwardPacket(pkt *stack.PacketBuffer) *tcpip.Error {
}
defer r.Release()
- // TODO(b/143425874) Decrease the TTL field in forwarded packets.
+ // We need to do a deep copy of the IP packet because
+ // WriteHeaderIncludedPacket takes ownership of the packet buffer, but we do
+ // not own it.
+ newHdr := header.IPv6(stack.PayloadSince(pkt.NetworkHeader()))
+
+ // As per RFC 8200 section 3,
+ //
+ // Hop Limit 8-bit unsigned integer. Decremented by 1 by
+ // each node that forwards the packet.
+ newHdr.SetHopLimit(hopLimit - 1)
+
return r.WriteHeaderIncludedPacket(stack.NewPacketBuffer(stack.PacketBufferOptions{
ReserveHeaderBytes: int(r.MaxHeaderLength()),
- // We need to do a deep copy of the IP packet because
- // WriteHeaderIncludedPacket takes ownership of the packet buffer, but we do
- // not own it.
- Data: stack.PayloadSince(pkt.NetworkHeader()).ToVectorisedView(),
+ Data: buffer.View(newHdr).ToVectorisedView(),
}))
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-22 06:45:55 +0000