On Tue, Sep 20, 2016 at 7:27 AM, Sowmini Varadhan
<sowmini.varad...@oracle.com> wrote:
> The vxlan header is at offset (14 + 20 + 8) into the packet,
> so the vxh is not aligned in vxlan_build_skb. Use [get/put]_unaligned
> functions to modify flags and vni field in the vxh.
>
I'm wondering if VXLAN is just the tip of the iceberg. Wouldn't this
is also be a problem in GRE and Geneve when they encapsulate Ethernet?
What about the outer IP header, wouldn't that potentially have
unaligned accesses also when creating it?
Tom
> Signed-off-by: Sowmini Varadhan <sowmini.varad...@oracle.com>
> ---
> drivers/net/vxlan.c | 10 ++++++----
> 1 files changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
> index e7d1668..f903fa4 100644
> --- a/drivers/net/vxlan.c
> +++ b/drivers/net/vxlan.c
> @@ -1751,15 +1751,17 @@ static int vxlan_build_skb(struct sk_buff *skb,
> struct dst_entry *dst,
> goto out_free;
>
> vxh = (struct vxlanhdr *) __skb_push(skb, sizeof(*vxh));
> - vxh->vx_flags = VXLAN_HF_VNI;
> - vxh->vx_vni = vxlan_vni_field(vni);
> + put_unaligned(VXLAN_HF_VNI, &vxh->vx_flags);
> + put_unaligned(vxlan_vni_field(vni), &vxh->vx_vni);
>
> if (type & SKB_GSO_TUNNEL_REMCSUM) {
> unsigned int start;
> + __be32 tmpvni = get_unaligned(&vxh->vx_vni);
>
> start = skb_checksum_start_offset(skb) - sizeof(struct
> vxlanhdr);
> - vxh->vx_vni |= vxlan_compute_rco(start, skb->csum_offset);
> - vxh->vx_flags |= VXLAN_HF_RCO;
> + tmpvni |= vxlan_compute_rco(start, skb->csum_offset);
> + put_unaligned(tmpvni, &vxh->vx_vni);
> + put_unaligned(VXLAN_HF_VNI | VXLAN_HF_RCO, &vxh->vx_flags);
>
> if (!skb_is_gso(skb)) {
> skb->ip_summed = CHECKSUM_NONE;
> --
> 1.7.1
>
