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On Fri, Oct 25, 2013 at 11:05:05AM +0200, Daniel Borkmann wrote:
> Unlike UDP or TCP, we do not take the pseudo-header into account
> in SCTP checksums [1]. So in case port mapping is the very same, we
> do not need to recalculate the whole SCTP checksum in software, which
> is expensive.
>
> Also, similarly as in IPVS/TCP, take into account when a private
> helper mangled the packet. In that case, we also need to recalculate
> the checksum even if ports might be same.
>
> [1] http://tools.ietf.org/html/rfc4960#section-6.8
>
> Signed-off-by: Daniel Borkmann <dborkman@xxxxxxxxxx>
Acked-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
> ---
> net/netfilter/ipvs/ip_vs_proto_sctp.c | 30 ++++++++++++++++++++++++------
> 1 file changed, 24 insertions(+), 6 deletions(-)
>
> diff --git a/net/netfilter/ipvs/ip_vs_proto_sctp.c
> b/net/netfilter/ipvs/ip_vs_proto_sctp.c
> index 9ca7aa0..e56661e 100644
> --- a/net/netfilter/ipvs/ip_vs_proto_sctp.c
> +++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c
> @@ -81,6 +81,7 @@ sctp_snat_handler(struct sk_buff *skb, struct
> ip_vs_protocol *pp,
> {
> sctp_sctphdr_t *sctph;
> unsigned int sctphoff = iph->len;
> + bool payload_csum = false;
>
> #ifdef CONFIG_IP_VS_IPV6
> if (cp->af == AF_INET6 && iph->fragoffs)
> @@ -92,19 +93,27 @@ sctp_snat_handler(struct sk_buff *skb, struct
> ip_vs_protocol *pp,
> return 0;
>
> if (unlikely(cp->app != NULL)) {
> + int ret;
> +
> /* Some checks before mangling */
> if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
> return 0;
>
> /* Call application helper if needed */
> - if (!ip_vs_app_pkt_out(cp, skb))
> + if (!(ret = ip_vs_app_pkt_out(cp, skb)))
> return 0;
> + /* ret=2: csum update is needed after payload mangling */
> + if (ret == 2)
> + payload_csum = true;
> }
>
> sctph = (void *) skb_network_header(skb) + sctphoff;
> - sctph->source = cp->vport;
>
> - sctp_nat_csum(skb, sctph, sctphoff);
> + /* Only update csum if we really have to */
> + if (sctph->source != cp->vport || payload_csum) {
> + sctph->source = cp->vport;
> + sctp_nat_csum(skb, sctph, sctphoff);
> + }
>
> return 1;
> }
> @@ -115,6 +124,7 @@ sctp_dnat_handler(struct sk_buff *skb, struct
> ip_vs_protocol *pp,
> {
> sctp_sctphdr_t *sctph;
> unsigned int sctphoff = iph->len;
> + bool payload_csum = false;
>
> #ifdef CONFIG_IP_VS_IPV6
> if (cp->af == AF_INET6 && iph->fragoffs)
> @@ -126,19 +136,27 @@ sctp_dnat_handler(struct sk_buff *skb, struct
> ip_vs_protocol *pp,
> return 0;
>
> if (unlikely(cp->app != NULL)) {
> + int ret;
> +
> /* Some checks before mangling */
> if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
> return 0;
>
> /* Call application helper if needed */
> - if (!ip_vs_app_pkt_in(cp, skb))
> + if (!(ret = ip_vs_app_pkt_in(cp, skb)))
> return 0;
> + /* ret=2: csum update is needed after payload mangling */
> + if (ret == 2)
> + payload_csum = true;
> }
>
> sctph = (void *) skb_network_header(skb) + sctphoff;
> - sctph->dest = cp->dport;
>
> - sctp_nat_csum(skb, sctph, sctphoff);
> + /* Only update csum if we really have to */
> + if (sctph->dest != cp->dport || payload_csum) {
> + sctph->dest = cp->dport;
> + sctp_nat_csum(skb, sctph, sctphoff);
> + }
>
> return 1;
> }
> --
> 1.7.11.7
>
> --
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