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>

net/batman-adv/icmp_socket.c

@@ -29,7 +29,7 @@
 static struct batadv_socket_client *batadv_socket_client_hash[256];
 
 static void batadv_socket_add_packet(struct batadv_socket_client *socket_client,
-				     struct batadv_icmp_packet_rr *icmp_packet,
+				     struct batadv_icmp_header *icmph,
 				     size_t icmp_len);
 
 void batadv_socket_init(void)
@@ -155,13 +155,13 @@ static ssize_t batadv_socket_write(struct file *file, const char __user *buff,
 	struct batadv_priv *bat_priv = socket_client->bat_priv;
 	struct batadv_hard_iface *primary_if = NULL;
 	struct sk_buff *skb;
-	struct batadv_icmp_packet_rr *icmp_packet;
-
+	struct batadv_icmp_packet_rr *icmp_packet_rr;
+	struct batadv_icmp_header *icmp_header;
 	struct batadv_orig_node *orig_node = NULL;
 	struct batadv_neigh_node *neigh_node = NULL;
 	size_t packet_len = sizeof(struct batadv_icmp_packet);
 
-	if (len < sizeof(struct batadv_icmp_packet)) {
+	if (len < sizeof(struct batadv_icmp_header)) {
 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 			   "Error - can't send packet from char device: invalid packet size\n");
 		return -EINVAL;
@@ -174,8 +174,10 @@ static ssize_t batadv_socket_write(struct file *file, const char __user *buff,
 		goto out;
 	}
 
-	if (len >= sizeof(struct batadv_icmp_packet_rr))
-		packet_len = sizeof(struct batadv_icmp_packet_rr);
+	if (len >= BATADV_ICMP_MAX_PACKET_SIZE)
+		packet_len = BATADV_ICMP_MAX_PACKET_SIZE;
+	else
+		packet_len = len;
 
 	skb = netdev_alloc_skb_ip_align(NULL, packet_len + ETH_HLEN);
 	if (!skb) {
@@ -185,67 +187,78 @@ static ssize_t batadv_socket_write(struct file *file, const char __user *buff,
 
 	skb->priority = TC_PRIO_CONTROL;
 	skb_reserve(skb, ETH_HLEN);
-	icmp_packet = (struct batadv_icmp_packet_rr *)skb_put(skb, packet_len);
+	icmp_header = (struct batadv_icmp_header *)skb_put(skb, packet_len);
 
-	if (copy_from_user(icmp_packet, buff, packet_len)) {
+	if (copy_from_user(icmp_header, buff, packet_len)) {
 		len = -EFAULT;
 		goto free_skb;
 	}
 
-	if (icmp_packet->icmph.header.packet_type != BATADV_ICMP) {
+	if (icmp_header->header.packet_type != BATADV_ICMP) {
 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 			   "Error - can't send packet from char device: got bogus packet type (expected: BAT_ICMP)\n");
 		len = -EINVAL;
 		goto free_skb;
 	}
 
-	if (icmp_packet->icmph.msg_type != BATADV_ECHO_REQUEST) {
+	switch (icmp_header->msg_type) {
+	case BATADV_ECHO_REQUEST:
+		if (len < sizeof(struct batadv_icmp_packet)) {
+			batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
+				   "Error - can't send packet from char device: invalid packet size\n");
+			len = -EINVAL;
+			goto free_skb;
+		}
+
+		if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
+			goto dst_unreach;
+
+		orig_node = batadv_orig_hash_find(bat_priv, icmp_header->dst);
+		if (!orig_node)
+			goto dst_unreach;
+
+		neigh_node = batadv_orig_node_get_router(orig_node);
+		if (!neigh_node)
+			goto dst_unreach;
+
+		if (!neigh_node->if_incoming)
+			goto dst_unreach;
+
+		if (neigh_node->if_incoming->if_status != BATADV_IF_ACTIVE)
+			goto dst_unreach;
+
+		icmp_packet_rr = (struct batadv_icmp_packet_rr *)icmp_header;
+		if (packet_len == sizeof(*icmp_packet_rr))
+			memcpy(icmp_packet_rr->rr,
+			       neigh_node->if_incoming->net_dev->dev_addr,
+			       ETH_ALEN);
+
+		break;
+	default:
 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
-			   "Error - can't send packet from char device: got bogus message type (expected: ECHO_REQUEST)\n");
+			   "Error - can't send packet from char device: got unknown message type\n");
 		len = -EINVAL;
 		goto free_skb;
 	}
 
-	icmp_packet->icmph.uid = socket_client->index;
+	icmp_header->uid = socket_client->index;
 
-	if (icmp_packet->icmph.header.version != BATADV_COMPAT_VERSION) {
-		icmp_packet->icmph.msg_type = BATADV_PARAMETER_PROBLEM;
-		icmp_packet->icmph.header.version = BATADV_COMPAT_VERSION;
-		batadv_socket_add_packet(socket_client, icmp_packet,
+	if (icmp_header->header.version != BATADV_COMPAT_VERSION) {
+		icmp_header->msg_type = BATADV_PARAMETER_PROBLEM;
+		icmp_header->header.version = BATADV_COMPAT_VERSION;
+		batadv_socket_add_packet(socket_client, icmp_header,
 					 packet_len);
 		goto free_skb;
 	}
 
-	if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
-		goto dst_unreach;
-
-	orig_node = batadv_orig_hash_find(bat_priv, icmp_packet->icmph.dst);
-	if (!orig_node)
-		goto dst_unreach;
-
-	neigh_node = batadv_orig_node_get_router(orig_node);
-	if (!neigh_node)
-		goto dst_unreach;
-
-	if (!neigh_node->if_incoming)
-		goto dst_unreach;
-
-	if (neigh_node->if_incoming->if_status != BATADV_IF_ACTIVE)
-		goto dst_unreach;
-
-	memcpy(icmp_packet->icmph.orig,
-	       primary_if->net_dev->dev_addr, ETH_ALEN);
-
-	if (packet_len == sizeof(struct batadv_icmp_packet_rr))
-		memcpy(icmp_packet->rr,
-		       neigh_node->if_incoming->net_dev->dev_addr, ETH_ALEN);
+	memcpy(icmp_header->orig, primary_if->net_dev->dev_addr, ETH_ALEN);
 
 	batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
 	goto out;
 
 dst_unreach:
-	icmp_packet->icmph.msg_type = BATADV_DESTINATION_UNREACHABLE;
-	batadv_socket_add_packet(socket_client, icmp_packet, packet_len);
+	icmp_header->msg_type = BATADV_DESTINATION_UNREACHABLE;
+	batadv_socket_add_packet(socket_client, icmp_header, packet_len);
 free_skb:
 	kfree_skb(skb);
 out:
@@ -298,27 +311,40 @@ int batadv_socket_setup(struct batadv_priv *bat_priv)
 	return -ENOMEM;
 }
 
+/**
+ * batadv_socket_receive_packet - schedule an icmp packet to be sent to userspace
+ *  on an icmp socket.
+ * @socket_client: the socket this packet belongs to
+ * @icmph: pointer to the header of the icmp packet
+ * @icmp_len: total length of the icmp packet
+ */
 static void batadv_socket_add_packet(struct batadv_socket_client *socket_client,
-				     struct batadv_icmp_packet_rr *icmp_packet,
+				     struct batadv_icmp_header *icmph,
 				     size_t icmp_len)
 {
 	struct batadv_socket_packet *socket_packet;
+	size_t len;
 
 	socket_packet = kmalloc(sizeof(*socket_packet), GFP_ATOMIC);
 
 	if (!socket_packet)
 		return;
 
+	len = icmp_len;
+	/* check the maximum length before filling the buffer */
+	if (len > sizeof(socket_packet->icmp_packet))
+		len = sizeof(socket_packet->icmp_packet);
+
 	INIT_LIST_HEAD(&socket_packet->list);
-	memcpy(&socket_packet->icmp_packet, icmp_packet, icmp_len);
-	socket_packet->icmp_len = icmp_len;
+	memcpy(&socket_packet->icmp_packet, icmph, len);
+	socket_packet->icmp_len = len;
 
 	spin_lock_bh(&socket_client->lock);
 
 	/* while waiting for the lock the socket_client could have been
 	 * deleted
 	 */
-	if (!batadv_socket_client_hash[icmp_packet->icmph.uid]) {
+	if (!batadv_socket_client_hash[icmph->uid]) {
 		spin_unlock_bh(&socket_client->lock);
 		kfree(socket_packet);
 		return;
@@ -342,12 +368,18 @@ static void batadv_socket_add_packet(struct batadv_socket_client *socket_client,
 	wake_up(&socket_client->queue_wait);
 }
 
-void batadv_socket_receive_packet(struct batadv_icmp_packet_rr *icmp_packet,
+/**
+ * batadv_socket_receive_packet - schedule an icmp packet to be received
+ *  locally and sent to userspace.
+ * @icmph: pointer to the header of the icmp packet
+ * @icmp_len: total length of the icmp packet
+ */
+void batadv_socket_receive_packet(struct batadv_icmp_header *icmph,
 				  size_t icmp_len)
 {
 	struct batadv_socket_client *hash;
 
-	hash = batadv_socket_client_hash[icmp_packet->icmph.uid];
+	hash = batadv_socket_client_hash[icmph->uid];
 	if (hash)
-		batadv_socket_add_packet(hash, icmp_packet, icmp_len);
+		batadv_socket_add_packet(hash, icmph, icmp_len);
 }

net/batman-adv/icmp_socket.h

@@ -24,7 +24,7 @@
 
 void batadv_socket_init(void);
 int batadv_socket_setup(struct batadv_priv *bat_priv);
-void batadv_socket_receive_packet(struct batadv_icmp_packet_rr *icmp_packet,
+void batadv_socket_receive_packet(struct batadv_icmp_header *icmph,
 				  size_t icmp_len);
 
 #endif /* _NET_BATMAN_ADV_ICMP_SOCKET_H_ */

net/batman-adv/packet.h

@@ -239,6 +239,8 @@ struct batadv_icmp_packet_rr {
 	uint8_t  rr[BATADV_RR_LEN][ETH_ALEN];
 };
 
+#define BATADV_ICMP_MAX_PACKET_SIZE	sizeof(struct batadv_icmp_packet_rr)
+
 /* All packet headers in front of an ethernet header have to be completely
  * divisible by 2 but not by 4 to make the payload after the ethernet
  * header again 4 bytes boundary aligned.