Re: [dpdk-dev] [PATCH] net/tap: fix zeroed flow mask configurations

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

On Thu, Aug 02, 2018 at 10:33:00AM +0000, Matan Azrad wrote:
> The rte_flow meaning of zero flow mask configuration is to match all
> the range of the item value.
> For example, the flow eth / ipv4 dst spec 1.2.3.4 dst mask 0.0.0.0
> should much all the ipv4 traffic from the rte_flow API perspective.
> 
> From some kernel perspectives the above rule means to ignore all the
> ipv4 traffic (e.g. Ubuntu 16.04, 4.15.10).
> 
> Due to the fact that the tap PMD should provide the rte_flow meaning,
> it is necessary to ignore the spec in case the mask is zero when it
> forwards such like flows to the kernel.
> So, the above rule should be translated to eth / ipv4 to get the
> correct meaning.
> 
> Ignore spec configurations when the mask is zero.

I would go further, one should be able to match IP address 0.0.0.0 for
instance. The PMD should only trust the mask on all fields without looking
at spec. See below for suggestions.

> Fixes: de96fe68ae95 ("net/tap: add basic flow API patterns and actions")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Matan Azrad <matan@mellanox.com>
> ---
>  drivers/net/tap/tap_flow.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/tap/tap_flow.c b/drivers/net/tap/tap_flow.c
> index 6b60e6d..993e6f6 100644
> --- a/drivers/net/tap/tap_flow.c
> +++ b/drivers/net/tap/tap_flow.c
> @@ -537,7 +537,8 @@ tap_flow_create_eth(const struct rte_flow_item *item, void *data)
>  	if (!flow)
>  		return 0;
>  	msg = &flow->msg;
> -	if (!is_zero_ether_addr(&spec->dst)) {
> +	if (!is_zero_ether_addr(&spec->dst) &&

This check should be removed.

> +	    !is_zero_ether_addr(&mask->dst)) {
>  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_ETH_DST, ETHER_ADDR_LEN,
>  			   &spec->dst.addr_bytes);
>  		tap_nlattr_add(&msg->nh,
> @@ -651,13 +652,13 @@ tap_flow_create_ipv4(const struct rte_flow_item *item, void *data)
>  		info->eth_type = htons(ETH_P_IP);
>  	if (!spec)
>  		return 0;
> -	if (spec->hdr.dst_addr) {
> +	if (spec->hdr.dst_addr && mask->hdr.dst_addr) {

Ditto (before &&).

>  		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_DST,
>  			     spec->hdr.dst_addr);
>  		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_DST_MASK,
>  			     mask->hdr.dst_addr);
>  	}
> -	if (spec->hdr.src_addr) {
> +	if (spec->hdr.src_addr && mask->hdr.src_addr) {

Ditto.

>  		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_SRC,
>  			     spec->hdr.src_addr);
>  		tap_nlattr_add32(&msg->nh, TCA_FLOWER_KEY_IPV4_SRC_MASK,
> @@ -707,13 +708,15 @@ tap_flow_create_ipv6(const struct rte_flow_item *item, void *data)
>  		info->eth_type = htons(ETH_P_IPV6);
>  	if (!spec)
>  		return 0;
> -	if (memcmp(spec->hdr.dst_addr, empty_addr, 16)) {
> +	if (memcmp(spec->hdr.dst_addr, empty_addr, 16) &&

Ditto.

> +	    memcmp(mask->hdr.dst_addr, empty_addr, 16)) {
>  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_DST,
>  			   sizeof(spec->hdr.dst_addr), &spec->hdr.dst_addr);
>  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_DST_MASK,
>  			   sizeof(mask->hdr.dst_addr), &mask->hdr.dst_addr);
>  	}
> -	if (memcmp(spec->hdr.src_addr, empty_addr, 16)) {
> +	if (memcmp(spec->hdr.src_addr, empty_addr, 16) &&

Ditto.

> +	    memcmp(mask->hdr.src_addr, empty_addr, 16)) {
>  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_SRC,
>  			   sizeof(spec->hdr.src_addr), &spec->hdr.src_addr);
>  		tap_nlattr_add(&msg->nh, TCA_FLOWER_KEY_IPV6_SRC_MASK,
> -- 
> 2.7.4
> 

-- 
Adrien Mazarguil
6WIND