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authorHannes Frederic Sowa <hannes@stressinduktion.org>2013-10-23 11:06:55 +0200
committerDavid S. Miller <davem@davemloft.net>2013-10-23 17:01:40 -0400
commite7b519ba55aeb675daee1d304e80d752c385f7f0 (patch)
treef9152523b9420b14557f22675b0e9ffab5d7b0b9 /net/ipv4
parentdf33db0f5efe8895203d221b9e701c0a61832c76 (diff)
downloadlinux-e7b519ba55aeb675daee1d304e80d752c385f7f0.tar.bz2
ipv4: initialize ip4_frags hash secret as late as possible
Defer the generation of the first hash secret for the ipv4 fragmentation cache as late as possible. ip4_frags.rnd gets initial seeded by inet_frags_init and regulary reseeded by inet_frag_secret_rebuild. Either we call ipqhashfn directly from ip_fragment.c in which case we initialize the secret directly. If we first get called by inet_frag_secret_rebuild we install a new secret by a manual call to get_random_bytes. This secret will be overwritten as soon as the first call to ipqhashfn happens. This is safe because we won't race while publishing the new secrets with anyone else. Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/ip_fragment.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index b66910aaef4d..2481993a4970 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -106,6 +106,7 @@ struct ip4_create_arg {
static unsigned int ipqhashfn(__be16 id, __be32 saddr, __be32 daddr, u8 prot)
{
+ net_get_random_once(&ip4_frags.rnd, sizeof(ip4_frags.rnd));
return jhash_3words((__force u32)id << 16 | prot,
(__force u32)saddr, (__force u32)daddr,
ip4_frags.rnd) & (INETFRAGS_HASHSZ - 1);