net: implement a SO_DOMAIN getsockoption
This sockopt goes in line with SO_TYPE and SO_PROTOCOL. It makes it
possible for userspace programs to pass around file descriptors — I
am referring to arguments-to-functions, but it may even work for the
fd passing over UNIX sockets — without needing to also pass the
auxiliary information (PF_INET6/IPPROTO_TCP).
Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/sock.c b/net/core/sock.c
index ebce661..3ac34ea 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -483,6 +483,7 @@
break;
case SO_TYPE:
case SO_PROTOCOL:
+ case SO_DOMAIN:
case SO_ERROR:
ret = -ENOPROTOOPT;
break;
@@ -769,6 +770,10 @@
v.val = sk->sk_protocol;
break;
+ case SO_DOMAIN:
+ v.val = sk->sk_family;
+ break;
+
case SO_ERROR:
v.val = -sock_error(sk);
if (v.val == 0)