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[2a02:1811:50e:f0f0:d05d:939:f42b:f575]) by smtp.gmail.com with ESMTPSA id v13sm3597682edl.9.2020.08.06.04.06.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Aug 2020 04:06:45 -0700 (PDT) From: Tim Froidcoeur To: tim.froidcoeur@tessares.net, "David S. Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI , Jakub Kicinski , Patrick McHardy , KOVACS Krisztian Cc: matthieu.baerts@tessares.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net v2 2/2] net: initialize fastreuse on inet_inherit_port Date: Thu, 6 Aug 2020 13:06:31 +0200 Message-Id: <20200806110631.475855-3-tim.froidcoeur@tessares.net> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200806110631.475855-1-tim.froidcoeur@tessares.net> References: <20200806110631.475855-1-tim.froidcoeur@tessares.net> MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In the case of TPROXY, bind_conflict optimizations for SO_REUSEADDR or SO_REUSEPORT are broken, possibly resulting in O(n) instead of O(1) bind behaviour or in the incorrect reuse of a bind. the kernel keeps track for each bind_bucket if all sockets in the bind_bucket support SO_REUSEADDR or SO_REUSEPORT in two fastreuse flags. These flags allow skipping the costly bind_conflict check when possible (meaning when all sockets have the proper SO_REUSE option). For every socket added to a bind_bucket, these flags need to be updated. As soon as a socket that does not support reuse is added, the flag is set to false and will never go back to true, unless the bind_bucket is deleted. Note that there is no mechanism to re-evaluate these flags when a socket is removed (this might make sense when removing a socket that would not allow reuse; this leaves room for a future patch). For this optimization to work, it is mandatory that these flags are properly initialized and updated. When a child socket is created from a listen socket in __inet_inherit_port, the TPROXY case could create a new bind bucket without properly initializing these flags, thus preventing the optimization to work. Alternatively, a socket not allowing reuse could be added to an existing bind bucket without updating the flags, causing bind_conflict to never be called as it should. Call inet_csk_update_fastreuse when __inet_inherit_port decides to create a new bind_bucket or use a different bind_bucket than the one of the listen socket. Fixes: 093d282321da ("tproxy: fix hash locking issue when using port redirection in __inet_inherit_port()") Acked-by: Matthieu Baerts Signed-off-by: Tim Froidcoeur --- net/ipv4/inet_hashtables.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index 2bbaaf0c7176..006a34b18537 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -163,6 +163,7 @@ int __inet_inherit_port(const struct sock *sk, struct sock *child) return -ENOMEM; } } + inet_csk_update_fastreuse(tb, child); } inet_bind_hash(child, tb, port); spin_unlock(&head->lock);