From ae593067dbed83010fee8ad59bab7948f3d3601f Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 21 Feb 2013 12:18:52 +0000 Subject: ipv6: use a stronger hash for tcp [ Upstream commit 08dcdbf6a7b9d14c2302c5bd0c5390ddf122f664 ] It looks like its possible to open thousands of TCP IPv6 sessions on a server, all landing in a single slot of TCP hash table. Incoming packets have to lookup sockets in a very long list. We should hash all bits from foreign IPv6 addresses, using a salt and hash mix, not a simple XOR. inet6_ehashfn() can also separately use the ports, instead of xoring them. Reported-by: Neal Cardwell Signed-off-by: Eric Dumazet Cc: Yuchung Cheng Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/net/inet6_hashtables.h | 8 ++++---- include/net/inet_sock.h | 1 + include/net/ipv6.h | 12 ++++++++++++ 3 files changed, 17 insertions(+), 4 deletions(-) (limited to 'include') diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h index e46674d..f9ce2fa 100644 --- a/include/net/inet6_hashtables.h +++ b/include/net/inet6_hashtables.h @@ -28,16 +28,16 @@ struct inet_hashinfo; -/* I have no idea if this is a good hash for v6 or not. -DaveM */ static inline unsigned int inet6_ehashfn(struct net *net, const struct in6_addr *laddr, const u16 lport, const struct in6_addr *faddr, const __be16 fport) { - u32 ports = (lport ^ (__force u16)fport); + u32 ports = (((u32)lport) << 16) | (__force u32)fport; return jhash_3words((__force u32)laddr->s6_addr32[3], - (__force u32)faddr->s6_addr32[3], - ports, inet_ehash_secret + net_hash_mix(net)); + ipv6_addr_jhash(faddr), + ports, + inet_ehash_secret + net_hash_mix(net)); } static inline int inet6_sk_ehashfn(const struct sock *sk) diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h index 14dd9c7..26490b3 100644 --- a/include/net/inet_sock.h +++ b/include/net/inet_sock.h @@ -199,6 +199,7 @@ static inline void inet_sk_copy_descendant(struct sock *sk_to, extern int inet_sk_rebuild_header(struct sock *sk); extern u32 inet_ehash_secret; +extern u32 ipv6_hash_secret; extern void build_ehash_secret(void); static inline unsigned int inet_ehashfn(struct net *net, diff --git a/include/net/ipv6.h b/include/net/ipv6.h index c39121f..879aadf 100644 --- a/include/net/ipv6.h +++ b/include/net/ipv6.h @@ -15,6 +15,7 @@ #include #include +#include #include #include #include @@ -386,6 +387,17 @@ struct ip6_create_arg { void ip6_frag_init(struct inet_frag_queue *q, void *a); int ip6_frag_match(struct inet_frag_queue *q, void *a); +/* more secured version of ipv6_addr_hash() */ +static inline u32 ipv6_addr_jhash(const struct in6_addr *a) +{ + u32 v = (__force u32)a->s6_addr32[0] ^ (__force u32)a->s6_addr32[1]; + + return jhash_3words(v, + (__force u32)a->s6_addr32[2], + (__force u32)a->s6_addr32[3], + ipv6_hash_secret); +} + static inline int ipv6_addr_any(const struct in6_addr *a) { return (a->s6_addr32[0] | a->s6_addr32[1] | -- cgit v1.1