Re: [dpdk-dev] [PATCH] ethdev: add packet integrity checks

[Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>]

On 4/5/21 9:04 PM, Ori Kam wrote:
> Currently, DPDK application can offload the checksum check,
> and report it in the mbuf.
> 
> However, as more and more applications are offloading some or all
> logic and action to the HW, there is a need to check the packet
> integrity so the right decision can be taken.
> 
> The application logic can be positive meaning if the packet is
> valid jump / do  actions, or negative if packet is not valid
> jump to SW / do actions (like drop)  a, and add default flow
> (match all in low priority) that will direct the miss packet
> to the miss path.
> 
> Since currenlty rte_flow works in positive way the assumtion is
> that the postive way will be the common way in this case also.
> 
> When thinking what is the best API to implement such feature,
> we need to considure the following (in no specific order):
> 1. API breakage.

First of all I disagree that "API breakage" is put as a top
priority. Design is a top priority, since it is a long term.
aPI breakage is just a short term inconvenient. Of course,
others may disagree, but that's my point of view.

> 2. Simplicity.
> 3. Performance.
> 4. HW capabilities.
> 5. rte_flow limitation.
> 6. Flexability.
> 
> First option: Add integrity flags to each of the items.
> For example add checksum_ok to ipv4 item.
> 
> Pros:
> 1. No new rte_flow item.
> 2. Simple in the way that on each item the app can see
> what checks are available.

3. Natively supports various tunnels without any extra
   changes in a shared item for all layers.

> 
> Cons:
> 1. API breakage.
> 2. increase number of flows, since app can't add global rule and
>    must have dedicated flow for each of the flow combinations, for example
>    matching on icmp traffic or UDP/TCP  traffic with IPv4 / IPv6 will
>    result in 5 flows.

Could you expand it? Shouldn't HW offloaded flows with good
checksums go into dedicated queues where as bad packets go
via default path (i.e. no extra rules)?

> 
> Second option: dedicated item
> 
> Pros:
> 1. No API breakage, and there will be no for some time due to having
>    extra space. (by using bits)
> 2. Just one flow to support the icmp or UDP/TCP traffic with IPv4 /
>    IPv6.

It depends on how bad (or good0 packets are handled.

> 3. Simplicity application can just look at one place to see all possible
>    checks.

It is a drawback from my point of view, since IPv4 checksum
check is out of IPv4 match item. I.e. analyzing IPv4 you should
take a look at 2 different flow items.

> 4. Allow future support for more tests.

It is the same for both solution since per-item solution
can keep reserved bits which may be used in the future.

> 
> Cons:
> 1. New item, that holds number of fields from different items.

2. Not that nice for tunnels.

> 
> For starter the following bits are suggested:
> 1. packet_ok - means that all HW checks depending on packet layer have
>    passed. This may mean that in some HW such flow should be splited to
>    number of flows or fail.
> 2. l2_ok - all check flor layer 2 have passed.
> 3. l3_ok - all check flor layer 2 have passed. If packet doens't have
>    l3 layer this check shoudl fail.
> 4. l4_ok - all check flor layer 2 have passed. If packet doesn't
>    have l4 layer this check should fail.
> 5. l2_crc_ok - the layer 2 crc is O.K. it is possible that the crc will
>    be O.K. but the l3_ok will be 0. it is not possible that l2_crc_ok will
>    be 0 and the l3_ok will be 0.
> 6. ipv4_csum_ok - IPv4 checksum is O.K.
> 7. l4_csum_ok - layer 4 checksum is O.K.
> 8. l3_len_OK - check that the reported layer 3 len is smaller than the
>    packet len.
> 
> Example of usage:
> 1. check packets from all possible layers for integrity.
>    flow create integrity spec packet_ok = 1 mask packet_ok = 1 .....
> 
> 2. Check only packet with layer 4 (UDP / TCP)
>    flow create integrity spec l3_ok = 1, l4_ok = 1 mask l3_ok = 1 l4_ok = 1
> 
> Signed-off-by: Ori Kam <orika@nvidia.com>
> ---
>  doc/guides/prog_guide/rte_flow.rst | 19 ++++++++++++++++
>  lib/librte_ethdev/rte_flow.h       | 46 ++++++++++++++++++++++++++++++++++++++
>  2 files changed, 65 insertions(+)
> 
> diff --git a/doc/guides/prog_guide/rte_flow.rst b/doc/guides/prog_guide/rte_flow.rst
> index aec2ba1..58b116e 100644
> --- a/doc/guides/prog_guide/rte_flow.rst
> +++ b/doc/guides/prog_guide/rte_flow.rst
> @@ -1398,6 +1398,25 @@ Matches a eCPRI header.
>  - ``hdr``: eCPRI header definition (``rte_ecpri.h``).
>  - Default ``mask`` matches nothing, for all eCPRI messages.
>  
> +Item: ``PACKET_INTEGRITY_CHECKS``
> +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> +
> +Matches packet integrity.
> +
> +- ``level``: the encapsulation level that should be checked. level 0 means the
> +  default PMD mode (Can be inner most / outermost). value of 1 means outermost
> +  and higher value means inner header. See also RSS level.
> +- ``packet_ok``: All HW packet integrity checks have passed based on the max
> +  layer of the packet.
> +  layer of the packet.
> +- ``l2_ok``: all layer 2 HW integrity checks passed.
> +- ``l3_ok``: all layer 3 HW integrity checks passed.
> +- ``l4_ok``: all layer 3 HW integrity checks passed.
> +- ``l2_crc_ok``: layer 2 crc check passed.
> +- ``ipv4_csum_ok``: ipv4 checksum check passed.
> +- ``l4_csum_ok``: layer 4 checksum check passed.
> +- ``l3_len_ok``: the layer 3 len is smaller than the packet len.
> +
>  Actions
>  ~~~~~~~
>  
> diff --git a/lib/librte_ethdev/rte_flow.h b/lib/librte_ethdev/rte_flow.h
> index 6cc5713..f6888a1 100644
> --- a/lib/librte_ethdev/rte_flow.h
> +++ b/lib/librte_ethdev/rte_flow.h
> @@ -551,6 +551,15 @@ enum rte_flow_item_type {
>  	 * See struct rte_flow_item_geneve_opt
>  	 */
>  	RTE_FLOW_ITEM_TYPE_GENEVE_OPT,
> +
> +	/**
> +	 * [META]
> +	 *
> +	 * Matches on packet integrity.
> +	 *
> +	 * See struct rte_flow_item_packet_integrity_checks.
> +	 */
> +	RTE_FLOW_ITEM_TYPE_PACKET_INTEGRITY_CHECKS,
>  };
>  
>  /**
> @@ -1685,6 +1694,43 @@ struct rte_flow_item_geneve_opt {
>  };
>  #endif
>  
> +struct rte_flow_item_packet_integrity_checks {
> +	uint32_t level;
> +	/**< Packet encapsulation level the item should apply to.
> +	 * @see rte_flow_action_rss
> +	 */
> +RTE_STD_C11
> +	union {
> +		struct {
> +			uint64_t packet_ok:1;
> +			/** The packet is valid after passing all HW checks. */
> +			uint64_t l2_ok:1;
> +			/**< L2 layer is valid after passing all HW checks. */
> +			uint64_t l3_ok:1;
> +			/**< L3 layer is valid after passing all HW checks. */
> +			uint64_t l4_ok:1;
> +			/**< L4 layer is valid after passing all HW checks. */
> +			uint64_t l2_crc_ok:1;
> +			/**< L2 layer checksum is valid. */
> +			uint64_t ipv4_csum_ok:1;
> +			/**< L3 layer checksum is valid. */
> +			uint64_t l4_csum_ok:1;
> +			/**< L4 layer checksum is valid. */
> +			uint64_t l3_len_ok:1;
> +			/**< The l3 len is smaller than the packet len. */
> +			uint64_t reserved:56;
> +		};
> +		uint64_t  value;
> +	};
> +};
> +
> +#ifndef __cplusplus
> +static const struct rte_flow_item_sanity_checks
> +	rte_flow_item_sanity_checks_mask = {
> +		.value = 0,
> +};
> +#endif
> +
>  /**
>   * Matching pattern item definition.
>   *
>