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| 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 /net/ipv4 | |
| parent | 0ab8a9f5fa94ac625c1f19acc48db299416c6d49 (diff) | |
| download | lwn-08dcdbf6a7b9d14c2302c5bd0c5390ddf122f664.tar.gz lwn-08dcdbf6a7b9d14c2302c5bd0c5390ddf122f664.zip | |
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>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/af_inet.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c index e225a4e5b572..9cbcb94a4c6d 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); |