diff options
Diffstat (limited to 'pkg/tcpip/network/ipv4/icmp.go')
| -rw-r--r-- | pkg/tcpip/network/ipv4/icmp.go | 40 |
1 files changed, 24 insertions, 16 deletions
diff --git a/pkg/tcpip/network/ipv4/icmp.go b/pkg/tcpip/network/ipv4/icmp.go index eab9a530c..3407755ed 100644 --- a/pkg/tcpip/network/ipv4/icmp.go +++ b/pkg/tcpip/network/ipv4/icmp.go @@ -102,8 +102,6 @@ func (e *endpoint) handleICMP(r *stack.Route, pkt *stack.PacketBuffer) { e.dispatcher.DeliverTransportPacket(r, header.ICMPv4ProtocolNumber, pkt) - remoteLinkAddr := r.RemoteLinkAddress - // As per RFC 1122 section 3.2.1.3, when a host sends any datagram, the IP // source address MUST be one of its own IP addresses (but not a broadcast // or multicast address). @@ -119,9 +117,6 @@ func (e *endpoint) handleICMP(r *stack.Route, pkt *stack.PacketBuffer) { } defer r.Release() - // Use the remote link address from the incoming packet. - r.ResolveWith(remoteLinkAddr) - // TODO(gvisor.dev/issue/3810:) When adding protocol numbers into the // header information, we may have to change this code to handle the // ICMP header no longer being in the data buffer. @@ -244,13 +239,7 @@ func (*icmpReasonProtoUnreachable) isICMPReason() {} // the problematic packet. It incorporates as much of that packet as // possible as well as any error metadata as is available. returnError // expects pkt to hold a valid IPv4 packet as per the wire format. -func returnError(r *stack.Route, reason icmpReason, pkt *stack.PacketBuffer) *tcpip.Error { - sent := r.Stats().ICMP.V4PacketsSent - if !r.Stack().AllowICMPMessage() { - sent.RateLimited.Increment() - return nil - } - +func (p *protocol) returnError(r *stack.Route, reason icmpReason, pkt *stack.PacketBuffer) *tcpip.Error { // We check we are responding only when we are allowed to. // See RFC 1812 section 4.3.2.7 (shown below). // @@ -279,6 +268,25 @@ func returnError(r *stack.Route, reason icmpReason, pkt *stack.PacketBuffer) *tc return nil } + // 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(r.NICID(), r.LocalAddress, r.RemoteAddress, ProtocolNumber, false /* multicastLoop */) + if err != nil { + return err + } + defer route.Release() + // From this point on, the incoming route should no longer be used; route + // must be used to send the ICMP error. + r = nil + + sent := p.stack.Stats().ICMP.V4PacketsSent + if !p.stack.AllowICMPMessage() { + sent.RateLimited.Increment() + return nil + } + networkHeader := pkt.NetworkHeader().View() transportHeader := pkt.TransportHeader().View() @@ -329,11 +337,11 @@ func returnError(r *stack.Route, reason icmpReason, pkt *stack.PacketBuffer) *tc // least 8 bytes of the payload must be included. Today linux and other // systems implement the RFC 1812 definition and not the original // requirement. We treat 8 bytes as the minimum but will try send more. - mtu := int(r.MTU()) + mtu := int(route.MTU()) if mtu > header.IPv4MinimumProcessableDatagramSize { mtu = header.IPv4MinimumProcessableDatagramSize } - headerLen := int(r.MaxHeaderLength()) + header.ICMPv4MinimumSize + headerLen := int(route.MaxHeaderLength()) + header.ICMPv4MinimumSize available := int(mtu) - headerLen if available < header.IPv4MinimumSize+header.ICMPv4MinimumErrorPayloadSize { @@ -378,11 +386,11 @@ func returnError(r *stack.Route, reason icmpReason, pkt *stack.PacketBuffer) *tc icmpHdr.SetChecksum(header.ICMPv4Checksum(icmpHdr, icmpPkt.Data)) counter := sent.DstUnreachable - if err := r.WritePacket( + if err := route.WritePacket( nil, /* gso */ stack.NetworkHeaderParams{ Protocol: header.ICMPv4ProtocolNumber, - TTL: r.DefaultTTL(), + TTL: route.DefaultTTL(), TOS: stack.DefaultTOS, }, icmpPkt, |