netfilter: use nfnetlink_unicast()

Replace netlink_unicast() calls by nfnetlink_unicast() which already
deals with translating EAGAIN to ENOBUFS as the nfnetlink core expects.

nfnetlink_unicast() calls nlmsg_unicast() which returns zero in case of
success, otherwise the netlink core function netlink_rcv_skb() turns
err > 0 into an acknowlegment.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 18 insertions, 47 deletions

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 8690fc07030f..220f51f055ab 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1628,9 +1628,8 @@ static int ctnetlink_get_conntrack(struct sk_buff *skb,
 
 	ct = nf_ct_tuplehash_to_ctrack(h);
 
-	err = -ENOMEM;
 	skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
-	if (skb2 == NULL) {
+	if (!skb2) {
 		nf_ct_put(ct);
 		return -ENOMEM;
 	}
@@ -1640,21 +1639,12 @@ static int ctnetlink_get_conntrack(struct sk_buff *skb,
 				  NFNL_MSG_TYPE(info->nlh->nlmsg_type), ct,
 				  true, 0);
 	nf_ct_put(ct);
-	if (err <= 0)
-		goto free;
-
-	err = netlink_unicast(info->sk, skb2, NETLINK_CB(skb).portid,
-			      MSG_DONTWAIT);
-	if (err < 0)
-		goto out;
-
-	return 0;
+	if (err <= 0) {
+		kfree_skb(skb2);
+		return -ENOMEM;
+	}
 
-free:
-	kfree_skb(skb2);
-out:
-	/* this avoids a loop in nfnetlink. */
-	return err == -EAGAIN ? -ENOBUFS : err;
+	return nfnetlink_unicast(skb2, info->net, NETLINK_CB(skb).portid);
 }
 
 static int ctnetlink_done_list(struct netlink_callback *cb)
@@ -2590,21 +2580,12 @@ static int ctnetlink_stat_ct(struct sk_buff *skb, const struct nfnl_info *info,
 					  info->nlh->nlmsg_seq,
 					  NFNL_MSG_TYPE(info->nlh->nlmsg_type),
 					  sock_net(skb->sk));
-	if (err <= 0)
-		goto free;
-
-	err = netlink_unicast(info->sk, skb2, NETLINK_CB(skb).portid,
-			      MSG_DONTWAIT);
-	if (err < 0)
-		goto out;
-
-	return 0;
+	if (err <= 0) {
+		kfree_skb(skb2);
+		return -ENOMEM;
+	}
 
-free:
-	kfree_skb(skb2);
-out:
-	/* this avoids a loop in nfnetlink. */
-	return err == -EAGAIN ? -ENOBUFS : err;
+	return nfnetlink_unicast(skb2, info->net, NETLINK_CB(skb).portid);
 }
 
 static const struct nla_policy exp_nla_policy[CTA_EXPECT_MAX+1] = {
@@ -3329,11 +3310,10 @@ static int ctnetlink_get_expect(struct sk_buff *skb,
 		}
 	}
 
-	err = -ENOMEM;
 	skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
-	if (skb2 == NULL) {
+	if (!skb2) {
 		nf_ct_expect_put(exp);
-		goto out;
+		return -ENOMEM;
 	}
 
 	rcu_read_lock();
@@ -3342,21 +3322,12 @@ static int ctnetlink_get_expect(struct sk_buff *skb,
 				      exp);
 	rcu_read_unlock();
 	nf_ct_expect_put(exp);
-	if (err <= 0)
-		goto free;
-
-	err = netlink_unicast(info->sk, skb2, NETLINK_CB(skb).portid,
-			      MSG_DONTWAIT);
-	if (err < 0)
-		goto out;
-
-	return 0;
+	if (err <= 0) {
+		kfree_skb(skb2);
+		return -ENOMEM;
+	}
 
-free:
-	kfree_skb(skb2);
-out:
-	/* this avoids a loop in nfnetlink. */
-	return err == -EAGAIN ? -ENOBUFS : err;
+	return nfnetlink_unicast(skb2, info->net, NETLINK_CB(skb).portid);
 }
 
 static bool expect_iter_name(struct nf_conntrack_expect *exp, void *data)