inet_diag: Introduce socket family checks

The new API will specify family to work with. Teach the existing
socket walking code to bypass not interesting ones.

To preserve compatibility with existing behavior the _compat code
sets interesting family to AF_UNSPEC to dump them all.
Signed-off-by: NPavel Emelyanov <xemul@parallels.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/inet_diag.c

@@ -743,6 +743,10 @@ static int __inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
 					continue;
 				}
 
+				if (r->sdiag_family != AF_UNSPEC &&
+						sk->sk_family != r->sdiag_family)
+					goto next_listen;
+
 				if (r->id.idiag_sport != inet->inet_sport &&
 				    r->id.idiag_sport)
 					goto next_listen;
@@ -808,6 +812,9 @@ static int __inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
 				goto next_normal;
 			if (!(r->idiag_states & (1 << sk->sk_state)))
 				goto next_normal;
+			if (r->sdiag_family != AF_UNSPEC &&
+					sk->sk_family != r->sdiag_family)
+				goto next_normal;
 			if (r->id.idiag_sport != inet->inet_sport &&
 			    r->id.idiag_sport)
 				goto next_normal;
@@ -830,6 +837,9 @@ static int __inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
 
 				if (num < s_num)
 					goto next_dying;
+				if (r->sdiag_family != AF_UNSPEC &&
+						tw->tw_family != r->sdiag_family)
+					goto next_dying;
 				if (r->id.idiag_sport != tw->tw_sport &&
 				    r->id.idiag_sport)
 					goto next_dying;
@@ -873,7 +883,7 @@ static int inet_diag_dump_compat(struct sk_buff *skb, struct netlink_callback *c
 	struct nlattr *bc = NULL;
 	int hdrlen = sizeof(struct inet_diag_req_compat);
 
-	req.sdiag_family = rc->idiag_family;
+	req.sdiag_family = AF_UNSPEC; /* compatibility */
 	req.sdiag_protocol = inet_diag_type2proto(cb->nlh->nlmsg_type);
 	req.idiag_ext = rc->idiag_ext;
 	req.idiag_states = rc->idiag_states;