[PATCH V3 RFC 2/2] ixgbe: ixgbe_atr() compute l4_proto only if non-paged data has network/transport headers

[Sowmini Varadhan]

For some Tx paths (e.g., tpacket_snd()), ixgbe_atr may be
passed down an sk_buff that has the network and transport
header in the paged data, so it needs to make sure these
headers are available in the headlen bytes to calculate the
l4_proto.

This patch expect that network and transport headers are
already available in the non-paged header dat.  The assumption
is that the caller has set this up if l4_proto based Tx
steering is desired.

Signed-off-by: Sowmini Varadhan <sowmini.varad...@oracle.com>
---
v3: add unlikely(); remove needless check for hdr.network against
    skb_tail_pointer(); refactor check to make sure we have tcp header
    in non-paged part.

 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c |   17 +++++++++++++++++
 1 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c 
b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index eceb47b..a9d2b0c 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
@@ -54,6 +54,7 @@
 #include <net/pkt_cls.h>
 #include <net/tc_act/tc_gact.h>
 #include <net/tc_act/tc_mirred.h>
+#include <net/vxlan.h>
 
 #include "ixgbe.h"
 #include "ixgbe_common.h"
@@ -7651,11 +7652,17 @@ static void ixgbe_atr(struct ixgbe_ring *ring,
        /* snag network header to get L4 type and address */
        skb = first->skb;
        hdr.network = skb_network_header(skb);
+       if (unlikely(hdr.network <= skb->data))
+               return;
        if (skb->encapsulation &&
            first->protocol == htons(ETH_P_IP) &&
            hdr.ipv4->protocol == IPPROTO_UDP) {
                struct ixgbe_adapter *adapter = q_vector->adapter;
 
+               if (unlikely(skb_tail_pointer(skb) < hdr.network +
+                                           VXLAN_HEADROOM))
+                       return;
+
                /* verify the port is recognized as VXLAN */
                if (adapter->vxlan_port &&
                    udp_hdr(skb)->dest == adapter->vxlan_port)
@@ -7666,6 +7673,12 @@ static void ixgbe_atr(struct ixgbe_ring *ring,
                        hdr.network = skb_inner_network_header(skb);
        }
 
+       /* Make sure we have at least [minimum IPv4 header + TCP]
+        * or [IPv6 header] bytes
+        */
+       if (unlikely(skb_tail_pointer(skb) < hdr.network + 40))
+               return;
+
        /* Currently only IPv4/IPv6 with TCP is supported */
        switch (hdr.ipv4->version) {
        case IPVERSION:
@@ -7685,6 +7698,10 @@ static void ixgbe_atr(struct ixgbe_ring *ring,
        if (l4_proto != IPPROTO_TCP)
                return;
 
+       if (unlikely(skb_tail_pointer(skb) < hdr.network +
+                                            hlen + sizeof(struct tcphdr)))
+                       return;
+
        th = (struct tcphdr *)(hdr.network + hlen);
 
        /* skip this packet since the socket is closing */
-- 
1.7.1