diff options
| author | Ghanan Gowripalan <ghanan@google.com> | 2020-08-08 17:43:15 -0700 |
|---|---|---|
| committer | gVisor bot <gvisor-bot@google.com> | 2020-08-08 17:45:19 -0700 |
| commit | b404b5c255214a37d7f787f9fe24bb8e22509eb4 (patch) | |
| tree | 904e6f0959b6db7c48fb71eeaa243642a24717ff /pkg/tcpip/network/ipv4/icmp.go | |
| parent | 13a8ae81b2361cd32f8e73d14ca5b9bca9569b1a (diff) | |
Use unicast source for ICMP echo replies
Packets MUST NOT use a non-unicast source address for ICMP
Echo Replies.
Test: integration_test.TestPingMulticastBroadcast
PiperOrigin-RevId: 325634380
Diffstat (limited to 'pkg/tcpip/network/ipv4/icmp.go')
| -rw-r--r-- | pkg/tcpip/network/ipv4/icmp.go | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/pkg/tcpip/network/ipv4/icmp.go b/pkg/tcpip/network/ipv4/icmp.go index 83e71cb8c..94803a359 100644 --- a/pkg/tcpip/network/ipv4/icmp.go +++ b/pkg/tcpip/network/ipv4/icmp.go @@ -96,6 +96,26 @@ func (e *endpoint) handleICMP(r *stack.Route, pkt *stack.PacketBuffer) { NetworkHeader: append(buffer.View(nil), pkt.NetworkHeader...), }) + 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). + localAddr := r.LocalAddress + if r.IsInboundBroadcast() || header.IsV4MulticastAddress(r.LocalAddress) { + localAddr = "" + } + + r, err := r.Stack().FindRoute(e.NICID(), localAddr, r.RemoteAddress, ProtocolNumber, false /* multicastLoop */) + if err != nil { + // If we cannot find a route to the destination, silently drop the packet. + return + } + defer r.Release() + + // Use the remote link address from the incoming packet. + r.ResolveWith(remoteLinkAddr) + vv := pkt.Data.Clone(nil) vv.TrimFront(header.ICMPv4MinimumSize) hdr := buffer.NewPrependable(int(r.MaxHeaderLength()) + header.ICMPv4MinimumSize) |