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| author |   Willy Tarreau <w@1wt.eu> | 2022-05-02 10:46:14 +0200 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-06-25 11:49:18 +0200 |
| commit | 9b40c2b72362a5ea92128ca7b83307986ac6246f (patch) | |
| tree | 992ae09f6ca4a1e1cae62f37485f29892580a190 | |
| parent | tcp: increase source port perturb table to 2^16 (diff) | |
| download | linux-stable-9b40c2b72362a5ea92128ca7b83307986ac6246f.tar.xz linux-stable-9b40c2b72362a5ea92128ca7b83307986ac6246f.zip | |
tcp: drop the hash_32() part from the index calculation
commit e8161345ddbb66e449abde10d2fdce93f867eba9 upstream.
In commit 190cc82489f4 ("tcp: change source port randomizarion at
connect() time"), the table_perturb[] array was introduced and an
index was taken from the port_offset via hash_32(). But it turns
out that hash_32() performs a multiplication while the input here
comes from the output of SipHash in secure_seq, that is well
distributed enough to avoid the need for yet another hash.
Suggested-by: Amit Klein <aksecurity@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/ipv4/inet_hashtables.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index ddaa1be737b9..5295a579ec82 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -767,7 +767,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row, net_get_random_once(table_perturb, INET_TABLE_PERTURB_SIZE * sizeof(*table_perturb)); - index = hash_32(port_offset, INET_TABLE_PERTURB_SHIFT); + index = port_offset & (INET_TABLE_PERTURB_SIZE - 1); offset = READ_ONCE(table_perturb[index]) + (port_offset >> 32); offset %= remaining; |