linux-kernel - [PATCH 3.16 318/370] udp: prevent skbs lingering in tunnel socket queues

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Date:   Fri, 10 Mar 2017 11:46:23 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Hannes Frederic Sowa" <hannes@...essinduktion.org>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.16 318/370] udp: prevent skbs lingering in tunnel socket
 queues

3.16.42-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Hannes Frederic Sowa <hannes@...essinduktion.org>

[ Upstream commit e5aed006be918af163eb397e45aa5ea6cefd5e01 ]

In case we find a socket with encapsulation enabled we should call
the encap_recv function even if just a udp header without payload is
available. The callbacks are responsible for correctly verifying and
dropping the packets.

Also, in case the header validation fails for geneve and vxlan we
shouldn't put the skb back into the socket queue, no one will pick
them up there.  Instead we can simply discard them in the respective
encap_recv functions.

Signed-off-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
Signed-off-by: David S. Miller <davem@...emloft.net>
[bwh: Backported to 3.16:
 - Drop changes to geneve
 - vxlan error checking looked a bit different]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -1146,7 +1146,7 @@ static int vxlan_udp_encap_recv(struct s
 
 	/* Need Vxlan and inner Ethernet header to be present */
 	if (!pskb_may_pull(skb, VXLAN_HLEN))
-		goto error;
+		goto drop;
 
 	/* Return packets with reserved bits set */
 	vxh = (struct vxlanhdr *)(udp_hdr(skb) + 1);
@@ -1154,7 +1154,7 @@ static int vxlan_udp_encap_recv(struct s
 	    (vxh->vx_vni & htonl(0xff))) {
 		netdev_dbg(skb->dev, "invalid vxlan flags=%#x vni=%#x\n",
 			   ntohl(vxh->vx_flags), ntohl(vxh->vx_vni));
-		goto error;
+		goto drop;
 	}
 
 	if (iptunnel_pull_header(skb, VXLAN_HLEN, htons(ETH_P_TEB)))
@@ -1173,10 +1173,6 @@ drop:
 	/* Consume bad packet */
 	kfree_skb(skb);
 	return 0;
-
-error:
-	/* Return non vxlan pkt */
-	return 1;
 }
 
 static void vxlan_rcv(struct vxlan_sock *vs,
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1533,7 +1533,7 @@ int udp_queue_rcv_skb(struct sock *sk, s
 
 		/* if we're overly short, let UDP handle it */
 		encap_rcv = ACCESS_ONCE(up->encap_rcv);
-		if (skb->len > sizeof(struct udphdr) && encap_rcv != NULL) {
+		if (encap_rcv) {
 			int ret;
 
 			/* Verify checksum before giving to encap */
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -631,7 +631,7 @@ int udpv6_queue_rcv_skb(struct sock *sk,
 
 		/* if we're overly short, let UDP handle it */
 		encap_rcv = ACCESS_ONCE(up->encap_rcv);
-		if (skb->len > sizeof(struct udphdr) && encap_rcv != NULL) {
+		if (encap_rcv) {
 			int ret;
 
 			/* Verify checksum before giving to encap */