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authorTim Froidcoeur <tim.froidcoeur@tessares.net>2020-08-11 21:33:24 +0300
committerDavid S. Miller <davem@davemloft.net>2020-08-12 01:49:08 +0300
commitd76f3351cea2d927fdf70dd7c06898235035e84e (patch)
treee495432ba681692912df3ec8aafdd6466b3f5b06 /net
parent62ffc589abb176821662efc4525ee4ac0b9c3894 (diff)
downloadlinux-d76f3351cea2d927fdf70dd7c06898235035e84e.tar.xz
net: initialize fastreuse on inet_inherit_port
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 <matthieu.baerts@tessares.net> Signed-off-by: Tim Froidcoeur <tim.froidcoeur@tessares.net> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/inet_hashtables.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 4eb4cd8d20dd..239e54474b65 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);