Re: [dpdk-dev] [PATCH v2 2/2] ip_frag: use key length for key comparision

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 05-Nov-18 12:18 PM, Konstantin Ananyev wrote:
> Right now reassembly code relies on src_dst[] being all zeroes to
> determine is it  free/occupied entry in the fragments table.
> This is suboptimal and error prone - user can crash DPDK ip_reassembly
> app by something like the following scapy script:
> x=Ether(src=...,dst=...)/IP(dst='0.0.0.0',src='0.0.0.0',id=0)/('X'*1000)
> frags=fragment(x, fragsize=500)
> sendp(frags, iface=...)
> To overcome that issue and reduce overhead of
> 'key invalidate'  and 'key is empty' operations -
> add key_len into keys comparision procedure.
> 
> Fixes: 4f1a8f633862 ("ip_frag: add IPv6 reassembly")
> Cc: stable@dpdk.org
> 
> Reported-by: Ryan E Hall <ryan.e.hall@intel.com>
> Reported-by: Alexander V Gutkin <alexander.v.gutkin@intel.com>
> Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
> ---



> @@ -44,9 +44,17 @@ struct ip_frag {
>   
>   /** @internal <src addr, dst_addr, id> to uniquely identify fragmented datagram. */
>   struct ip_frag_key {
> -	uint64_t src_dst[4];      /**< src address, first 8 bytes used for IPv4 */
> -	uint32_t id;           /**< dst address */
> -	uint32_t key_len;      /**< src/dst key length */
> +	uint64_t src_dst[4];
> +	/**< src and dst address, only first 8 bytes used for IPv4 */
> +	RTE_STD_C11
> +	union {
> +		uint64_t id_key_len; /**< combined for easy fetch */
> +		__extension__
> +		struct {
> +			uint32_t id;       /**< packet id */
> +			uint32_t key_len;  /**< src/dst key length */
> +		};
> +	};
>   };

Would that break ABI?

>   
>   /**
> 


-- 
Thanks,
Anatoly