Re: [dpdk-dev] [PATCH v2] ip_frag: fix fragmenting ipv4 packet with header option

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

> 
> From: Pu Xu <583493798@qq.com>
> 
> When fragmenting ipv4 packet, the data offset should be calculated through
> the ihl field in ip header rather than using sizeof(struct rte_ipv4_hdr).
> 
> Fixes: 4c38e5532a07 ("ip_frag: refactor IPv4 fragmentation into a proper library")
> 
> Signed-off-by: Pu Xu <583493798@qq.com>
> ---
>  lib/librte_ip_frag/rte_ipv4_fragmentation.c | 34 +++++++++++++--------
>  1 file changed, 21 insertions(+), 13 deletions(-)
> 
> diff --git a/lib/librte_ip_frag/rte_ipv4_fragmentation.c b/lib/librte_ip_frag/rte_ipv4_fragmentation.c
> index e9de335ae..2e7739d02 100644
> --- a/lib/librte_ip_frag/rte_ipv4_fragmentation.c
> +++ b/lib/librte_ip_frag/rte_ipv4_fragmentation.c
> @@ -23,10 +23,10 @@
>  #define	IPV4_HDR_FO_ALIGN			(1 << RTE_IPV4_HDR_FO_SHIFT)
> 
>  static inline void __fill_ipv4hdr_frag(struct rte_ipv4_hdr *dst,
> -		const struct rte_ipv4_hdr *src, uint16_t len, uint16_t fofs,
> -		uint16_t dofs, uint32_t mf)
> +		const struct rte_ipv4_hdr *src, uint16_t header_len,
> +		uint16_t len, uint16_t fofs, uint16_t dofs, uint32_t mf)
>  {
> -	rte_memcpy(dst, src, sizeof(*dst));
> +	rte_memcpy(dst, src, header_len);
>  	fofs = (uint16_t)(fofs + (dofs >> RTE_IPV4_HDR_FO_SHIFT));
>  	fofs = (uint16_t)(fofs | mf << RTE_IPV4_HDR_MF_SHIFT);
>  	dst->fragment_offset = rte_cpu_to_be_16(fofs);
> @@ -74,7 +74,7 @@ rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
>  	struct rte_ipv4_hdr *in_hdr;
>  	uint32_t out_pkt_pos, in_seg_data_pos;
>  	uint32_t more_in_segs;
> -	uint16_t fragment_offset, flag_offset, frag_size;
> +	uint16_t fragment_offset, flag_offset, frag_size, header_len;
>  	uint16_t frag_bytes_remaining;
> 
>  	/*
> @@ -86,14 +86,22 @@ rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
>  	    unlikely(mtu_size < RTE_ETHER_MIN_MTU))
>  		return -EINVAL;
> 
> +	in_hdr = rte_pktmbuf_mtod(pkt_in, struct rte_ipv4_hdr *);
> +	header_len = (in_hdr->version_ihl & RTE_IPV4_HDR_IHL_MASK) *
> +	    RTE_IPV4_IHL_MULTIPLIER;
> +
> +	/* Check IP header length */
> +	if (unlikely(pkt_in->data_len < header_len) ||
> +	    unlikely(mtu_size < header_len))
> +		return -EINVAL;
> +
>  	/*
>  	 * Ensure the IP payload length of all fragments is aligned to a
>  	 * multiple of 8 bytes as per RFC791 section 2.3.
>  	 */
> -	frag_size = RTE_ALIGN_FLOOR((mtu_size - sizeof(struct rte_ipv4_hdr)),
> +	frag_size = RTE_ALIGN_FLOOR((mtu_size - header_len),
>  				    IPV4_HDR_FO_ALIGN);
> 
> -	in_hdr = rte_pktmbuf_mtod(pkt_in, struct rte_ipv4_hdr *);
>  	flag_offset = rte_cpu_to_be_16(in_hdr->fragment_offset);
> 
>  	/* If Don't Fragment flag is set */
> @@ -102,11 +110,11 @@ rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
> 
>  	/* Check that pkts_out is big enough to hold all fragments */
>  	if (unlikely(frag_size * nb_pkts_out <
> -	    (uint16_t)(pkt_in->pkt_len - sizeof(struct rte_ipv4_hdr))))
> +	    (uint16_t)(pkt_in->pkt_len - header_len)))
>  		return -EINVAL;
> 
>  	in_seg = pkt_in;
> -	in_seg_data_pos = sizeof(struct rte_ipv4_hdr);
> +	in_seg_data_pos = header_len;
>  	out_pkt_pos = 0;
>  	fragment_offset = 0;
> 
> @@ -124,8 +132,8 @@ rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
>  		}
> 
>  		/* Reserve space for the IP header that will be built later */
> -		out_pkt->data_len = sizeof(struct rte_ipv4_hdr);
> -		out_pkt->pkt_len = sizeof(struct rte_ipv4_hdr);
> +		out_pkt->data_len = header_len;
> +		out_pkt->pkt_len = header_len;
>  		frag_bytes_remaining = frag_size;
> 
>  		out_seg_prev = out_pkt;
> @@ -176,14 +184,14 @@ rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
> 
>  		out_hdr = rte_pktmbuf_mtod(out_pkt, struct rte_ipv4_hdr *);
> 
> -		__fill_ipv4hdr_frag(out_hdr, in_hdr,
> +		__fill_ipv4hdr_frag(out_hdr, in_hdr, header_len,
>  		    (uint16_t)out_pkt->pkt_len,
>  		    flag_offset, fragment_offset, more_in_segs);
> 
>  		fragment_offset = (uint16_t)(fragment_offset +
> -		    out_pkt->pkt_len - sizeof(struct rte_ipv4_hdr));
> +		    out_pkt->pkt_len - header_len);
> 
> -		out_pkt->l3_len = sizeof(struct rte_ipv4_hdr);
> +		out_pkt->l3_len = header_len;
> 
>  		/* Write the fragment to the output list */
>  		pkts_out[out_pkt_pos] = out_pkt;
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

> 2.17.0