linux-kernel - [PATCH AUTOSEL 5.15 13/19] tcp: use different parts of the port

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Message-Id: <20220510154429.153677-13-sashal@kernel.org>
Date:   Tue, 10 May 2022 11:44:23 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Willy Tarreau <w@....eu>, "Jason A . Donenfeld" <Jason@...c4.com>,
        Moshe Kol <moshe.kol@...l.huji.ac.il>,
        Yossi Gilad <yossi.gilad@...l.huji.ac.il>,
        Amit Klein <aksecurity@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Sasha Levin <sashal@...nel.org>, davem@...emloft.net,
        yoshfuji@...ux-ipv6.org, dsahern@...nel.org, pabeni@...hat.com,
        netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 5.15 13/19] tcp: use different parts of the port_offset for index and offset

From: Willy Tarreau <w@....eu>

[ Upstream commit 9e9b70ae923baf2b5e8a0ea4fd0c8451801ac526 ]

Amit Klein suggests that we use different parts of port_offset for the
table's index and the port offset so that there is no direct relation
between them.

Cc: Jason A. Donenfeld <Jason@...c4.com>
Cc: Moshe Kol <moshe.kol@...l.huji.ac.il>
Cc: Yossi Gilad <yossi.gilad@...l.huji.ac.il>
Cc: Amit Klein <aksecurity@...il.com>
Reviewed-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Willy Tarreau <w@....eu>
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/ipv4/inet_hashtables.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 606a4220ebb9..81a33af8393d 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -777,7 +777,7 @@ int __inet_hash_connect(struct inet_timewait_death_row *death_row,
 	net_get_random_once(table_perturb, sizeof(table_perturb));
 	index = hash_32(port_offset, INET_TABLE_PERTURB_SHIFT);
 
-	offset = READ_ONCE(table_perturb[index]) + port_offset;
+	offset = READ_ONCE(table_perturb[index]) + (port_offset >> 32);
 	offset %= remaining;
 
 	/* In first pass we try ports of @low parity.
-- 
2.35.1