diff options
| author |   Willy Tarreau <w@1wt.eu> | 2022-05-02 10:46:14 +0200 |
|---|---|---|
| committer |   Jakub Kicinski <kuba@kernel.org> | 2022-05-04 19:22:33 -0700 |
| commit | e8161345ddbb66e449abde10d2fdce93f867eba9 (patch) | |
| tree | 57699c177cf0115d66ca9dc3eec9666d9f0a415d /net/ipv4 | |
| parent | tcp: increase source port perturb table to 2^16 (diff) | |
| download | linux-dev-e8161345ddbb66e449abde10d2fdce93f867eba9.tar.xz linux-dev-e8161345ddbb66e449abde10d2fdce93f867eba9.zip | |
tcp: drop the hash_32() part from the index calculation
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>
Diffstat (limited to 'net/ipv4')
| -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 cc5f66328b47..a5d57fa679ca 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -778,7 +778,7 @@ 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; |