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authorWilly Tarreau <w@1wt.eu>2022-05-02 10:46:14 +0200
committerJakub Kicinski <kuba@kernel.org>2022-05-04 19:22:33 -0700
commite8161345ddbb66e449abde10d2fdce93f867eba9 (patch)
tree57699c177cf0115d66ca9dc3eec9666d9f0a415d /net
parent4c2c8f03a5ab7cb04ec64724d7d176d00bcc91e5 (diff)
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')
-rw-r--r--net/ipv4/inet_hashtables.c2
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;