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netfilter: NFQUEUE: don't xor src/dst ip address for load distribution 

because reply packets need to go to the same nfqueue, src/dst ip
address were xor'd prior to jhash().

However, this causes bad distribution for some workloads, e.g.
flows a.b.1.{1,n} -> a.b.2.{1,n} all share the same hash value.

Avoid this by hashing both. To get same hash for replies,
first argument is the smaller address.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2012-06-04 02:53:54 +00:00 committed by Pablo Neira Ayuso
parent 8264deb818
commit 1da6dd0798
1 changed files with 19 additions and 9 deletions
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28
net/netfilter/xt_NFQUEUE.c
View File

@ -41,26 +41,36 @@ nfqueue_tg(struct sk_buff *skb, const struct xt_action_param *par)
static u32 hash_v4(const struct sk_buff *skb) static u32 hash_v4(const struct sk_buff *skb)
{ {
const struct iphdr *iph = ip_hdr(skb); const struct iphdr *iph = ip_hdr(skb);
__be32 ipaddr;
/* packets in either direction go into same queue */ /* packets in either direction go into same queue */
ipaddr = iph->saddr ^ iph->daddr; if (iph->saddr < iph->daddr)
return jhash_3words((__force u32)iph->saddr,
(__force u32)iph->daddr, iph->protocol, jhash_initval);
return jhash_2words((__force u32)ipaddr, iph->protocol, jhash_initval); return jhash_3words((__force u32)iph->daddr,
(__force u32)iph->saddr, iph->protocol, jhash_initval);
} }
#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
static u32 hash_v6(const struct sk_buff *skb) static u32 hash_v6(const struct sk_buff *skb)
{ {
const struct ipv6hdr *ip6h = ipv6_hdr(skb); const struct ipv6hdr *ip6h = ipv6_hdr(skb);
__be32 addr[4]; u32 a, b, c;
addr[0] = ip6h->saddr.s6_addr32[0] ^ ip6h->daddr.s6_addr32[0]; if (ip6h->saddr.s6_addr32[3] < ip6h->daddr.s6_addr32[3]) {
addr[1] = ip6h->saddr.s6_addr32[1] ^ ip6h->daddr.s6_addr32[1]; a = (__force u32) ip6h->saddr.s6_addr32[3];
addr[2] = ip6h->saddr.s6_addr32[2] ^ ip6h->daddr.s6_addr32[2]; b = (__force u32) ip6h->daddr.s6_addr32[3];
addr[3] = ip6h->saddr.s6_addr32[3] ^ ip6h->daddr.s6_addr32[3]; } else {
b = (__force u32) ip6h->saddr.s6_addr32[3];
a = (__force u32) ip6h->daddr.s6_addr32[3];
}
return jhash2((__force u32 *)addr, ARRAY_SIZE(addr), jhash_initval); if (ip6h->saddr.s6_addr32[1] < ip6h->daddr.s6_addr32[1])
c = (__force u32) ip6h->saddr.s6_addr32[1];
else
c = (__force u32) ip6h->daddr.s6_addr32[1];
return jhash_3words(a, b, c, jhash_initval);
} }
#endif #endif