batman-adv: generalize batman-adv icmp packet handling

Instead of handling icmp packets only up to length of icmp_packet_rr,
the code should handle any icmp length size. Therefore the length
truncating is moved to when the packet is actually sent to userspace
(this does not support lengths longer than icmp_packet_rr yet). Longer
packets are forwarded without truncating.

This patch also cleans up some parts where the icmp header struct could
be used instead of other icmp_packet(_rr) structs to make the code more
readable.

Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>

1 files changed, 73 insertions, 47 deletions

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 71fba14..d4114d7 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -260,47 +260,65 @@ bool batadv_check_management_packet(struct sk_buff *skb,
 	return true;
 }
 
+/**
+ * batadv_recv_my_icmp_packet - receive an icmp packet locally
+ * @bat_priv: the bat priv with all the soft interface information
+ * @skb: icmp packet to process
+ *
+ * Returns NET_RX_SUCCESS if the packet has been consumed or NET_RX_DROP
+ * otherwise.
+ */
 static int batadv_recv_my_icmp_packet(struct batadv_priv *bat_priv,
-				      struct sk_buff *skb, size_t icmp_len)
+				      struct sk_buff *skb)
 {
 	struct batadv_hard_iface *primary_if = NULL;
 	struct batadv_orig_node *orig_node = NULL;
-	struct batadv_icmp_packet_rr *icmp_packet;
-	int ret = NET_RX_DROP;
+	struct batadv_icmp_header *icmph;
+	int res, ret = NET_RX_DROP;
 
-	icmp_packet = (struct batadv_icmp_packet_rr *)skb->data;
+	icmph = (struct batadv_icmp_header *)skb->data;
 
-	/* add data to device queue */
-	if (icmp_packet->icmph.msg_type != BATADV_ECHO_REQUEST) {
-		batadv_socket_receive_packet(icmp_packet, icmp_len);
-		goto out;
-	}
+	switch (icmph->msg_type) {
+	case BATADV_ECHO_REPLY:
+	case BATADV_DESTINATION_UNREACHABLE:
+	case BATADV_TTL_EXCEEDED:
+		/* receive the packet */
+		if (skb_linearize(skb) < 0)
+			break;
 
-	primary_if = batadv_primary_if_get_selected(bat_priv);
-	if (!primary_if)
-		goto out;
+		batadv_socket_receive_packet(icmph, skb->len);
+		break;
+	case BATADV_ECHO_REQUEST:
+		/* answer echo request (ping) */
+		primary_if = batadv_primary_if_get_selected(bat_priv);
+		if (!primary_if)
+			goto out;
 
-	/* answer echo request (ping) */
-	/* get routing information */
-	orig_node = batadv_orig_hash_find(bat_priv, icmp_packet->icmph.orig);
-	if (!orig_node)
-		goto out;
+		/* get routing information */
+		orig_node = batadv_orig_hash_find(bat_priv, icmph->orig);
+		if (!orig_node)
+			goto out;
 
-	/* create a copy of the skb, if needed, to modify it. */
-	if (skb_cow(skb, ETH_HLEN) < 0)
-		goto out;
+		/* create a copy of the skb, if needed, to modify it. */
+		if (skb_cow(skb, ETH_HLEN) < 0)
+			goto out;
 
-	icmp_packet = (struct batadv_icmp_packet_rr *)skb->data;
+		icmph = (struct batadv_icmp_header *)skb->data;
 
-	memcpy(icmp_packet->icmph.dst, icmp_packet->icmph.orig, ETH_ALEN);
-	memcpy(icmp_packet->icmph.orig, primary_if->net_dev->dev_addr,
-	       ETH_ALEN);
-	icmp_packet->icmph.msg_type = BATADV_ECHO_REPLY;
-	icmp_packet->icmph.header.ttl = BATADV_TTL;
+		memcpy(icmph->dst, icmph->orig, ETH_ALEN);
+		memcpy(icmph->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
+		icmph->msg_type = BATADV_ECHO_REPLY;
+		icmph->header.ttl = BATADV_TTL;
 
-	if (batadv_send_skb_to_orig(skb, orig_node, NULL) != NET_XMIT_DROP)
-		ret = NET_RX_SUCCESS;
+		res = batadv_send_skb_to_orig(skb, orig_node, NULL);
+		if (res != NET_XMIT_DROP)
+			ret = NET_RX_SUCCESS;
 
+		break;
+	default:
+		/* drop unknown type */
+		goto out;
+	}
 out:
 	if (primary_if)
 		batadv_hardif_free_ref(primary_if);
@@ -363,16 +381,13 @@ int batadv_recv_icmp_packet(struct sk_buff *skb,
 			    struct batadv_hard_iface *recv_if)
 {
 	struct batadv_priv *bat_priv = netdev_priv(recv_if->soft_iface);
-	struct batadv_icmp_packet_rr *icmp_packet;
+	struct batadv_icmp_header *icmph;
+	struct batadv_icmp_packet_rr *icmp_packet_rr;
 	struct ethhdr *ethhdr;
 	struct batadv_orig_node *orig_node = NULL;
-	int hdr_size = sizeof(struct batadv_icmp_packet);
+	int hdr_size = sizeof(struct batadv_icmp_header);
 	int ret = NET_RX_DROP;
 
-	/* we truncate all incoming icmp packets if they don't match our size */
-	if (skb->len >= sizeof(struct batadv_icmp_packet_rr))
-		hdr_size = sizeof(struct batadv_icmp_packet_rr);
-
 	/* drop packet if it has not necessary minimum size */
 	if (unlikely(!pskb_may_pull(skb, hdr_size)))
 		goto out;
@@ -391,28 +406,39 @@ int batadv_recv_icmp_packet(struct sk_buff *skb,
 	if (!batadv_is_my_mac(bat_priv, ethhdr->h_dest))
 		goto out;
 
-	icmp_packet = (struct batadv_icmp_packet_rr *)skb->data;
+	icmph = (struct batadv_icmp_header *)skb->data;
 
 	/* add record route information if not full */
-	if ((icmp_packet->icmph.msg_type == BATADV_ECHO_REPLY ||
-	     icmp_packet->icmph.msg_type == BATADV_ECHO_REQUEST) &&
-	    (hdr_size == sizeof(struct batadv_icmp_packet_rr)) &&
-	    (icmp_packet->rr_cur < BATADV_RR_LEN)) {
-		memcpy(&(icmp_packet->rr[icmp_packet->rr_cur]),
+	if ((icmph->msg_type == BATADV_ECHO_REPLY ||
+	     icmph->msg_type == BATADV_ECHO_REQUEST) &&
+	    (skb->len >= sizeof(struct batadv_icmp_packet_rr))) {
+		if (skb_linearize(skb) < 0)
+			goto out;
+
+		/* create a copy of the skb, if needed, to modify it. */
+		if (skb_cow(skb, ETH_HLEN) < 0)
+			goto out;
+
+		icmph = (struct batadv_icmp_header *)skb->data;
+		icmp_packet_rr = (struct batadv_icmp_packet_rr *)icmph;
+		if (icmp_packet_rr->rr_cur >= BATADV_RR_LEN)
+			goto out;
+
+		memcpy(&(icmp_packet_rr->rr[icmp_packet_rr->rr_cur]),
 		       ethhdr->h_dest, ETH_ALEN);
-		icmp_packet->rr_cur++;
+		icmp_packet_rr->rr_cur++;
 	}
 
 	/* packet for me */
-	if (batadv_is_my_mac(bat_priv, icmp_packet->icmph.dst))
-		return batadv_recv_my_icmp_packet(bat_priv, skb, hdr_size);
+	if (batadv_is_my_mac(bat_priv, icmph->dst))
+		return batadv_recv_my_icmp_packet(bat_priv, skb);
 
 	/* TTL exceeded */
-	if (icmp_packet->icmph.header.ttl < 2)
+	if (icmph->header.ttl < 2)
 		return batadv_recv_icmp_ttl_exceeded(bat_priv, skb);
 
 	/* get routing information */
-	orig_node = batadv_orig_hash_find(bat_priv, icmp_packet->icmph.dst);
+	orig_node = batadv_orig_hash_find(bat_priv, icmph->dst);
 	if (!orig_node)
 		goto out;
 
@@ -420,10 +446,10 @@ int batadv_recv_icmp_packet(struct sk_buff *skb,
 	if (skb_cow(skb, ETH_HLEN) < 0)
 		goto out;
 
-	icmp_packet = (struct batadv_icmp_packet_rr *)skb->data;
+	icmph = (struct batadv_icmp_header *)skb->data;
 
 	/* decrement ttl */
-	icmp_packet->icmph.header.ttl--;
+	icmph->header.ttl--;
 
 	/* route it */
 	if (batadv_send_skb_to_orig(skb, orig_node, recv_if) != NET_XMIT_DROP)