Support owner matching for iptables.

This feature will match UID and GID of the packet creator, for locally
generated packets. This match is only valid in the OUTPUT and POSTROUTING
chains. Forwarded packets do not have any socket associated with them.
Packets from kernel threads do have a socket, but usually no owner.

1 files changed, 10 insertions, 2 deletions

diff --git a/pkg/tcpip/transport/icmp/endpoint.go b/pkg/tcpip/transport/icmp/endpoint.go
index 613b12ead..b007302fb 100644
--- a/pkg/tcpip/transport/icmp/endpoint.go
+++ b/pkg/tcpip/transport/icmp/endpoint.go
@@ -73,6 +73,9 @@ type endpoint struct {
 	route         stack.Route `state:"manual"`
 	ttl           uint8
 	stats         tcpip.TransportEndpointStats `state:"nosave"`
+
+	// owner is used to get uid and gid of the packet.
+	owner tcpip.PacketOwner
 }
 
 func newEndpoint(s *stack.Stack, netProto tcpip.NetworkProtocolNumber, transProto tcpip.TransportProtocolNumber, waiterQueue *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
@@ -133,6 +136,10 @@ func (e *endpoint) Close() {
 // ModerateRecvBuf implements tcpip.Endpoint.ModerateRecvBuf.
 func (e *endpoint) ModerateRecvBuf(copied int) {}
 
+func (e *endpoint) SetOwner(owner tcpip.PacketOwner) {
+	e.owner = owner
+}
+
 // IPTables implements tcpip.Endpoint.IPTables.
 func (e *endpoint) IPTables() (stack.IPTables, error) {
 	return e.stack.IPTables(), nil
@@ -321,7 +328,7 @@ func (e *endpoint) write(p tcpip.Payloader, opts tcpip.WriteOptions) (int64, <-c
 
 	switch e.NetProto {
 	case header.IPv4ProtocolNumber:
-		err = send4(route, e.ID.LocalPort, v, e.ttl)
+		err = send4(route, e.ID.LocalPort, v, e.ttl, e.owner)
 
 	case header.IPv6ProtocolNumber:
 		err = send6(route, e.ID.LocalPort, v, e.ttl)
@@ -415,7 +422,7 @@ func (e *endpoint) GetSockOpt(opt interface{}) *tcpip.Error {
 	}
 }
 
-func send4(r *stack.Route, ident uint16, data buffer.View, ttl uint8) *tcpip.Error {
+func send4(r *stack.Route, ident uint16, data buffer.View, ttl uint8, owner tcpip.PacketOwner) *tcpip.Error {
 	if len(data) < header.ICMPv4MinimumSize {
 		return tcpip.ErrInvalidEndpointState
 	}
@@ -444,6 +451,7 @@ func send4(r *stack.Route, ident uint16, data buffer.View, ttl uint8) *tcpip.Err
 		Header:          hdr,
 		Data:            data.ToVectorisedView(),
 		TransportHeader: buffer.View(icmpv4),
+		Owner:           owner,
 	})
 }