diff options
author | Eric Dumazet <edumazet@google.com> | 2013-02-21 12:18:52 +0000 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2013-02-21 18:15:58 -0500 |
commit | 08dcdbf6a7b9d14c2302c5bd0c5390ddf122f664 (patch) | |
tree | fc1d00005fda323296b93064416d255b81fdab73 | |
parent | 0ab8a9f5fa94ac625c1f19acc48db299416c6d49 (diff) | |
download | kernel_goldelico_gta04-08dcdbf6a7b9d14c2302c5bd0c5390ddf122f664.zip kernel_goldelico_gta04-08dcdbf6a7b9d14c2302c5bd0c5390ddf122f664.tar.gz kernel_goldelico_gta04-08dcdbf6a7b9d14c2302c5bd0c5390ddf122f664.tar.bz2 |
ipv6: use a stronger hash for tcp
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 <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r-- | include/net/inet6_hashtables.h | 8 | ||||
-rw-r--r-- | include/net/inet_sock.h | 1 | ||||
-rw-r--r-- | include/net/ipv6.h | 12 | ||||
-rw-r--r-- | net/ipv4/af_inet.c | 9 |
4 files changed, 24 insertions, 6 deletions
diff --git a/include/net/inet6_hashtables.h b/include/net/inet6_hashtables.h index 7ca75cb..fd4ee01 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 a4196cb..7235ae7 100644 --- a/include/net/inet_sock.h +++ b/include/net/inet_sock.h @@ -203,6 +203,7 @@ 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 851d541..64d12e7 100644 --- a/include/net/ipv6.h +++ b/include/net/ipv6.h @@ -15,6 +15,7 @@ #include <linux/ipv6.h> #include <linux/hardirq.h> +#include <linux/jhash.h> #include <net/if_inet6.h> #include <net/ndisc.h> #include <net/flow.h> @@ -514,6 +515,17 @@ static inline u32 ipv6_addr_hash(const struct in6_addr *a) #endif } +/* 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 bool ipv6_addr_loopback(const struct in6_addr *a) { #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64 diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index e225a4e..9cbcb94 100644 --- a/net/ipv4/af_inet.c +++ b/net/ipv4/af_inet.c @@ -248,8 +248,12 @@ EXPORT_SYMBOL(inet_listen); u32 inet_ehash_secret __read_mostly; EXPORT_SYMBOL(inet_ehash_secret); +u32 ipv6_hash_secret __read_mostly; +EXPORT_SYMBOL(ipv6_hash_secret); + /* - * inet_ehash_secret must be set exactly once + * inet_ehash_secret must be set exactly once, and to a non nul value + * ipv6_hash_secret must be set exactly once. */ void build_ehash_secret(void) { @@ -259,7 +263,8 @@ void build_ehash_secret(void) get_random_bytes(&rnd, sizeof(rnd)); } while (rnd == 0); - cmpxchg(&inet_ehash_secret, 0, rnd); + if (cmpxchg(&inet_ehash_secret, 0, rnd) == 0) + get_random_bytes(&ipv6_hash_secret, sizeof(ipv6_hash_secret)); } EXPORT_SYMBOL(build_ehash_secret); |