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> --- 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 -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
