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Commit 1da6dd07 authored by Florian Westphal's avatar Florian Westphal Committed by Pablo Neira Ayuso
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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: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 8264deb8

net/netfilter/xt_NFQUEUE.c

+19 −9
Original line number Diff line number Diff line
@@ -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)

{

	const struct iphdr *iph = ip_hdr(skb);

	__be32 ipaddr;



	/* 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)

static u32 hash_v6(const struct sk_buff *skb)

{

	const struct ipv6hdr *ip6h = ipv6_hdr(skb);

	__be32 addr[4];

	u32 a, b, c;



	if (ip6h->saddr.s6_addr32[3] < ip6h->daddr.s6_addr32[3]) {

		a = (__force u32) ip6h->saddr.s6_addr32[3];

		b = (__force u32) ip6h->daddr.s6_addr32[3];

	} else {

		b = (__force u32) ip6h->saddr.s6_addr32[3];

		a = (__force u32) ip6h->daddr.s6_addr32[3];

	}



	addr[0] = ip6h->saddr.s6_addr32[0] ^ ip6h->daddr.s6_addr32[0];

	addr[1] = ip6h->saddr.s6_addr32[1] ^ ip6h->daddr.s6_addr32[1];

	addr[2] = ip6h->saddr.s6_addr32[2] ^ ip6h->daddr.s6_addr32[2];

	addr[3] = ip6h->saddr.s6_addr32[3] ^ ip6h->daddr.s6_addr32[3];

	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 jhash2((__force u32 *)addr, ARRAY_SIZE(addr), jhash_initval);

	return jhash_3words(a, b, c, jhash_initval);

}

#endif