[dpdk-dev] [PATCH] ipv4_fragmentation: fix fragmentation of ipv4 packet with optional header
Ananyev, Konstantin
konstantin.ananyev at intel.com
Wed Apr 29 13:38:50 CEST 2020
Hi,
First of all - if it is a fix, then we need to have:
Fixes: ...
And probably
Cc: stable at dpdk.org
As described here:
https://doc.dpdk.org/guides/contributing/patches.html
Second it would be good to add some text here -
problem statement and solution description.
>
> Signed-off-by: Pu Xu <583493798 at qq.com>
> ---
> lib/librte_ip_frag/rte_ipv4_fragmentation.c | 20 +++++++++++---------
> 1 file changed, 11 insertions(+), 9 deletions(-)
>
> diff --git a/lib/librte_ip_frag/rte_ipv4_fragmentation.c b/lib/librte_ip_frag/rte_ipv4_fragmentation.c
> index e9de335ae..156087ca3 100644
> --- a/lib/librte_ip_frag/rte_ipv4_fragmentation.c
> +++ b/lib/librte_ip_frag/rte_ipv4_fragmentation.c
> @@ -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 +86,16 @@ 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 & 0xf) * 4;
We do have a special define for that in librte_net/rte_ip.h:
** Internet header length mask for version_ihl field */
#define RTE_IPV4_HDR_IHL_MASK (0x0f)
/**
* Internet header length field multiplier (IHL field specifies overall header
* length in number of 4-byte words)
*/
#define RTE_IPV4_IHL_MULTIPLIER (4)
Please use them in the code above.
Also as now we are getting header_len from the packet itself,
It would be good to check that it contains a valid value.
Otherwise ill-formed ip-header can crash dpdk app.
> /*
> * 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 +104,11 @@ 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 +126,8 @@ 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;
> @@ -181,9 +183,9 @@ rte_ipv4_fragment_packet(struct rte_mbuf *pkt_in,
> flag_offset, fragment_offset, more_in_segs);
I think we have to update __fill_ipv4hdr_frag() too, otherwise options
from original header wouldn't be copied into the new header.
>
> 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;
> --
> 2.20.1
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