netfilter: xt_NFQUEUE: separate reusable code

This patch prepares the addition of nft_queue module by moving
reusable code into a header file.

This patch also converts NFQUEUE to use prandom_u32 to initialize
the random jhash seed as suggested by Florian Westphal.

Signed-off-by: Eric Leblond <eric@regit.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 62 insertions, 0 deletions

diff --git a/include/net/netfilter/nf_queue.h b/include/net/netfilter/nf_queue.h
index c1d5b3e34a21..84a53d780306 100644
--- a/include/net/netfilter/nf_queue.h
+++ b/include/net/netfilter/nf_queue.h
@@ -1,6 +1,10 @@
 #ifndef _NF_QUEUE_H
 #define _NF_QUEUE_H
 
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/jhash.h>
+
 /* Each queued (to userspace) skbuff has one of these. */
 struct nf_queue_entry {
         struct list_head        list;
@@ -33,4 +37,62 @@ void nf_reinject(struct nf_queue_entry *entry, unsigned int verdict);
 bool nf_queue_entry_get_refs(struct nf_queue_entry *entry);
 void nf_queue_entry_release_refs(struct nf_queue_entry *entry);
 
+static inline void init_hashrandom(u32 *jhash_initval)
+{
+        while (*jhash_initval == 0)
+                *jhash_initval = prandom_u32();
+}
+
+static inline u32 hash_v4(const struct sk_buff *skb, u32 jhash_initval)
+{
+        const struct iphdr *iph = ip_hdr(skb);
+
+        /* packets in either direction go into same queue */
+        if ((__force u32)iph->saddr < (__force u32)iph->daddr)
+                return jhash_3words((__force u32)iph->saddr,
+                        (__force u32)iph->daddr, 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 inline u32 hash_v6(const struct sk_buff *skb, u32 jhash_initval)
+{
+        const struct ipv6hdr *ip6h = ipv6_hdr(skb);
+        u32 a, b, c;
+
+        if ((__force u32)ip6h->saddr.s6_addr32[3] <
+            (__force u32)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];
+        }
+
+        if ((__force u32)ip6h->saddr.s6_addr32[1] <
+            (__force u32)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
+
+static inline u32
+nfqueue_hash(const struct sk_buff *skb, u16 queue, u16 queues_total, u8 family,
+             u32 jhash_initval)
+{
+        if (family == NFPROTO_IPV4)
+                queue += ((u64) hash_v4(skb, jhash_initval) * queues_total) >> 32;
+#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES)
+        else if (family == NFPROTO_IPV6)
+                queue += ((u64) hash_v6(skb, jhash_initval) * queues_total) >> 32;
+#endif
+
+        return queue;
+}
+
 #endif /* _NF_QUEUE_H */