batman-adv: Consume skb in receive handlers

Receiving functions in Linux consume the supplied skbuff. Doing the same in
the batadv_rx_handler functions makes the behavior more similar to the rest
of the Linux network code.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

net/batman-adv/bat_iv_ogm.c

@@ -1823,17 +1823,18 @@ static int batadv_iv_ogm_receive(struct sk_buff *skb,
 	struct batadv_ogm_packet *ogm_packet;
 	u8 *packet_pos;
 	int ogm_offset;
-	bool ret;
+	bool res;
+	int ret = NET_RX_DROP;
 
-	ret = batadv_check_management_packet(skb, if_incoming, BATADV_OGM_HLEN);
-	if (!ret)
-		return NET_RX_DROP;
+	res = batadv_check_management_packet(skb, if_incoming, BATADV_OGM_HLEN);
+	if (!res)
+		goto free_skb;
 
 	/* did we receive a B.A.T.M.A.N. IV OGM packet on an interface
 	 * that does not have B.A.T.M.A.N. IV enabled ?
 	 */
 	if (bat_priv->algo_ops->iface.enable != batadv_iv_ogm_iface_enable)
-		return NET_RX_DROP;
+		goto free_skb;
 
 	batadv_inc_counter(bat_priv, BATADV_CNT_MGMT_RX);
 	batadv_add_counter(bat_priv, BATADV_CNT_MGMT_RX_BYTES,
@@ -1854,8 +1855,15 @@ static int batadv_iv_ogm_receive(struct sk_buff *skb,
 		ogm_packet = (struct batadv_ogm_packet *)packet_pos;
 	}
 
-	consume_skb(skb);
-	return NET_RX_SUCCESS;
+	ret = NET_RX_SUCCESS;
+
+free_skb:
+	if (ret == NET_RX_SUCCESS)
+		consume_skb(skb);
+	else
+		kfree_skb(skb);
+
+	return ret;
 }
 
 #ifdef CONFIG_BATMAN_ADV_DEBUGFS

net/batman-adv/bat_v_elp.c

@@ -492,20 +492,21 @@ int batadv_v_elp_packet_recv(struct sk_buff *skb,
 	struct batadv_elp_packet *elp_packet;
 	struct batadv_hard_iface *primary_if;
 	struct ethhdr *ethhdr = (struct ethhdr *)skb_mac_header(skb);
-	bool ret;
+	bool res;
+	int ret = NET_RX_DROP;
 
-	ret = batadv_check_management_packet(skb, if_incoming, BATADV_ELP_HLEN);
-	if (!ret)
-		return NET_RX_DROP;
+	res = batadv_check_management_packet(skb, if_incoming, BATADV_ELP_HLEN);
+	if (!res)
+		goto free_skb;
 
 	if (batadv_is_my_mac(bat_priv, ethhdr->h_source))
-		return NET_RX_DROP;
+		goto free_skb;
 
 	/* did we receive a B.A.T.M.A.N. V ELP packet on an interface
 	 * that does not have B.A.T.M.A.N. V ELP enabled ?
 	 */
 	if (strcmp(bat_priv->algo_ops->name, "BATMAN_V") != 0)
-		return NET_RX_DROP;
+		goto free_skb;
 
 	elp_packet = (struct batadv_elp_packet *)skb->data;
 
@@ -516,14 +517,19 @@ int batadv_v_elp_packet_recv(struct sk_buff *skb,
 
 	primary_if = batadv_primary_if_get_selected(bat_priv);
 	if (!primary_if)
-		goto out;
+		goto free_skb;
 
 	batadv_v_elp_neigh_update(bat_priv, ethhdr->h_source, if_incoming,
 				  elp_packet);
 
-out:
-	if (primary_if)
-		batadv_hardif_put(primary_if);
-	consume_skb(skb);
-	return NET_RX_SUCCESS;
+	ret = NET_RX_SUCCESS;
+	batadv_hardif_put(primary_if);
+
+free_skb:
+	if (ret == NET_RX_SUCCESS)
+		consume_skb(skb);
+	else
+		kfree_skb(skb);
+
+	return ret;
 }

net/batman-adv/bat_v_ogm.c

@@ -810,18 +810,18 @@ int batadv_v_ogm_packet_recv(struct sk_buff *skb,
 	 * B.A.T.M.A.N. V enabled ?
 	 */
 	if (strcmp(bat_priv->algo_ops->name, "BATMAN_V") != 0)
-		return NET_RX_DROP;
+		goto free_skb;
 
 	if (!batadv_check_management_packet(skb, if_incoming, BATADV_OGM2_HLEN))
-		return NET_RX_DROP;
+		goto free_skb;
 
 	if (batadv_is_my_mac(bat_priv, ethhdr->h_source))
-		return NET_RX_DROP;
+		goto free_skb;
 
 	ogm_packet = (struct batadv_ogm2_packet *)skb->data;
 
 	if (batadv_is_my_mac(bat_priv, ogm_packet->orig))
-		return NET_RX_DROP;
+		goto free_skb;
 
 	batadv_inc_counter(bat_priv, BATADV_CNT_MGMT_RX);
 	batadv_add_counter(bat_priv, BATADV_CNT_MGMT_RX_BYTES,
@@ -842,7 +842,12 @@ int batadv_v_ogm_packet_recv(struct sk_buff *skb,
 	}
 
 	ret = NET_RX_SUCCESS;
-	consume_skb(skb);
+
+free_skb:
+	if (ret == NET_RX_SUCCESS)
+		consume_skb(skb);
+	else
+		kfree_skb(skb);
 
 	return ret;
 }

net/batman-adv/main.c

@@ -402,6 +402,8 @@ void batadv_skb_set_priority(struct sk_buff *skb, int offset)
 static int batadv_recv_unhandled_packet(struct sk_buff *skb,
 					struct batadv_hard_iface *recv_if)
 {
+	kfree_skb(skb);
+
 	return NET_RX_DROP;
 }
 
@@ -416,7 +418,6 @@ int batadv_batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
 	struct batadv_ogm_packet *batadv_ogm_packet;
 	struct batadv_hard_iface *hard_iface;
 	u8 idx;
-	int ret;
 
 	hard_iface = container_of(ptype, struct batadv_hard_iface,
 				  batman_adv_ptype);
@@ -466,14 +467,8 @@ int batadv_batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
 	/* reset control block to avoid left overs from previous users */
 	memset(skb->cb, 0, sizeof(struct batadv_skb_cb));
 
-	/* all receive handlers return whether they received or reused
-	 * the supplied skb. if not, we have to free the skb.
-	 */
 	idx = batadv_ogm_packet->packet_type;
-	ret = (*batadv_rx_handler[idx])(skb, hard_iface);
-
-	if (ret == NET_RX_DROP)
-		kfree_skb(skb);
+	(*batadv_rx_handler[idx])(skb, hard_iface);
 
 	batadv_hardif_put(hard_iface);
 

net/batman-adv/network-coding.c

@@ -1819,19 +1819,19 @@ static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
 
 	/* Check if network coding is enabled */
 	if (!atomic_read(&bat_priv->network_coding))
-		return NET_RX_DROP;
+		goto free_skb;
 
 	/* Make sure we can access (and remove) header */
 	if (unlikely(!pskb_may_pull(skb, hdr_size)))
-		return NET_RX_DROP;
+		goto free_skb;
 
 	coded_packet = (struct batadv_coded_packet *)skb->data;
 	ethhdr = eth_hdr(skb);
 
 	/* Verify frame is destined for us */
 	if (!batadv_is_my_mac(bat_priv, ethhdr->h_dest) &&
 	    !batadv_is_my_mac(bat_priv, coded_packet->second_dest))
-		return NET_RX_DROP;
+		goto free_skb;
 
 	/* Update stat counter */
 	if (batadv_is_my_mac(bat_priv, coded_packet->second_dest))
@@ -1841,7 +1841,7 @@ static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
 						   coded_packet);
 	if (!nc_packet) {
 		batadv_inc_counter(bat_priv, BATADV_CNT_NC_DECODE_FAILED);
-		return NET_RX_DROP;
+		goto free_skb;
 	}
 
 	/* Make skb's linear, because decoding accesses the entire buffer */
@@ -1867,6 +1867,9 @@ static int batadv_nc_recv_coded_packet(struct sk_buff *skb,
 
 free_nc_packet:
 	batadv_nc_packet_free(nc_packet, true);
+free_skb:
+	kfree_skb(skb);
+
 	return NET_RX_DROP;
 }