[ovs-dev] [PATCH] odp-execute: Extract l2 padding while executing check_pkt_len action.

Ilya Maximets i.maximets at ovn.org
Thu Jun 11 10:12:21 UTC 2020


On 6/11/20 12:02 PM, Ilya Maximets wrote:
> If dp-packet contains l2 padding its size will be larger than the
> actual size of a payload and action will work incorrectly.
> 
> Padding could be set during miniflow_extract() if detected.
> 
> CC: Numan Siddique <nusiddiq at redhat.com>
> Fixes: 5b34f8fc3b38 ("Add a new OVS action check_pkt_larger")
> Reported-by: Miroslav Kubiczek <miroslav.kubiczek at adaptivemobile.com>
> Reported-at: https://mail.openvswitch.org/pipermail/ovs-discuss/2020-May/050157.html
> Signed-off-by: Ilya Maximets <i.maximets at ovn.org>
> ---
> 
> I didn't test this, only checked existing unit tests.
> 
> Miroslav, could you, please, check if this works in your case?
> 
> It might be also good to write some unit test for this.
> 
>  lib/odp-execute.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/odp-execute.c b/lib/odp-execute.c
> index 6018e378a..548083cef 100644
> --- a/lib/odp-execute.c
> +++ b/lib/odp-execute.c
> @@ -761,10 +761,10 @@ odp_execute_check_pkt_len(void *dp, struct dp_packet *packet, bool steal,
>  
>      const struct nlattr *a;
>      struct dp_packet_batch pb;
> +    uint32_t size = dp_packet_size(packet) - dp_packet_l2_pad_size(packet);

We might also need to subtract dp_packet_get_cutlen() or use
dp_packet_get_send_len() instead of dp_packet_size() for the
same purpose, otherwise cutlen + check_pkt_len might not work
as expected.

>  
>      a = attrs[OVS_CHECK_PKT_LEN_ATTR_PKT_LEN];
> -    bool is_greater = dp_packet_size(packet) > nl_attr_get_u16(a);
> -    if (is_greater) {
> +    if (size > nl_attr_get_u16(a)) {
>          a = attrs[OVS_CHECK_PKT_LEN_ATTR_ACTIONS_IF_GREATER];
>      } else {
>          a = attrs[OVS_CHECK_PKT_LEN_ATTR_ACTIONS_IF_LESS_EQUAL];
> 



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