On Sat, Feb 6, 2016 at 2:52 PM, Tom Herbert <t...@herbertland.com> wrote:
> On Fri, Feb 5, 2016 at 3:28 PM, Alexander Duyck <adu...@mirantis.com> wrote:
>> This patch updates the gre checksum path to follow something much closer to
>> the UDP checksum path. By doing this we can avoid needing to do as much
>> header inspection and can just make use of the fields we were already
>> reading in the sk_buff structure.
>>
>> Signed-off-by: Alexander Duyck <adu...@mirantis.com>
>> ---
>> net/ipv4/gre_offload.c | 64
>> +++++++++++++++++++++++-------------------------
>> 1 file changed, 30 insertions(+), 34 deletions(-)
>>
>> diff --git a/net/ipv4/gre_offload.c b/net/ipv4/gre_offload.c
>> index 35a8dd35ed4e..c15441b5ff61 100644
>> --- a/net/ipv4/gre_offload.c
>> +++ b/net/ipv4/gre_offload.c
>> @@ -18,14 +18,14 @@
>> static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
>> netdev_features_t features)
>> {
>> + int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
>> struct sk_buff *segs = ERR_PTR(-EINVAL);
>> - int ghl;
>> struct gre_base_hdr *greh;
>> u16 mac_offset = skb->mac_header;
>> - int mac_len = skb->mac_len;
>> __be16 protocol = skb->protocol;
>> - int tnl_hlen;
>> - bool csum;
>> + u16 mac_len = skb->mac_len;
>> + int gre_offset, outer_hlen;
>> + bool need_csum;
>>
>> if (unlikely(skb_shinfo(skb)->gso_type &
>> ~(SKB_GSO_TCPV4 |
>> @@ -42,64 +42,60 @@ static struct sk_buff *gre_gso_segment(struct sk_buff
>> *skb,
>> if (!skb->encapsulation)
>> goto out;
>>
>> - if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
>> + if (unlikely(tnl_hlen < sizeof(struct gre_base_hdr)))
>> goto out;
>>
>> - greh = (struct gre_base_hdr *)skb_transport_header(skb);
>> -
>> - ghl = skb_inner_mac_header(skb) - skb_transport_header(skb);
>> - if (unlikely(ghl < sizeof(*greh)))
>> + if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
>> goto out;
>>
>> - csum = !!(greh->flags & GRE_CSUM);
>> - if (csum)
>> - skb->encap_hdr_csum = 1;
>> + greh = (struct gre_base_hdr *)skb_transport_header(skb);
>>
>> /* setup inner skb. */
>> skb->protocol = greh->protocol;
>> skb->encapsulation = 0;
>> -
>> - if (unlikely(!pskb_may_pull(skb, ghl)))
>> - goto out;
>> -
>> - __skb_pull(skb, ghl);
>> + __skb_pull(skb, tnl_hlen);
>> skb_reset_mac_header(skb);
>> skb_set_network_header(skb, skb_inner_network_offset(skb));
>> skb->mac_len = skb_inner_network_offset(skb);
>>
>> + need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_GRE_CSUM);
>
> Should we do a WARN_ON(need_csum && !(greh->flags & GRE_CSUM)) just to
> be conservative?
>
We could but what would be the point?
If there is an issue like that present in the kernel we should
probably fix it in build_header in ip_gre.c instead of trying to push
validation for the case into the GSO code.
- Alex
