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

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> -----Original Message-----
> From: Burakov, Anatoly
> Sent: Tuesday, November 6, 2018 10:54 AM
> To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; dev@dpdk.org
> Cc: stable@dpdk.org; Hall, Ryan E <ryan.e.hall@intel.com>; Gutkin, Alexander V <alexander.v.gutkin@intel.com>
> Subject: Re: [dpdk-dev] [PATCH v2 2/2] ip_frag: use key length for key comparision
> 
> 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?

No, size and layout of the structure  remains the same.
Konstantin