netdev - Re: [PATCH v5 net-next 1/6] net: bridge: add locked entry fdb flag to extend locked port feature

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Date:   Mon, 29 Aug 2022 13:34:21 +0200
From:   netdev@...io-technology.com
To:     Ido Schimmel <idosch@...dia.com>
Cc:     davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
        Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Kurt Kanzenbach <kurt@...utronix.de>,
        Hauke Mehrtens <hauke@...ke-m.de>,
        Woojung Huh <woojung.huh@...rochip.com>,
        UNGLinuxDriver@...rochip.com, Sean Wang <sean.wang@...iatek.com>,
        Landen Chao <Landen.Chao@...iatek.com>,
        DENG Qingfang <dqfext@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Ivan Vecera <ivecera@...hat.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Shuah Khan <shuah@...nel.org>,
        Christian Marangi <ansuelsmth@...il.com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Yuwei Wang <wangyuweihx@...il.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        bridge@...ts.linux-foundation.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v5 net-next 1/6] net: bridge: add locked entry fdb flag to
 extend locked port feature

On 2022-08-27 17:19, Ido Schimmel wrote:
> 
> How about the below (untested):
> 
> diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
> index 68b3e850bcb9..9143a94a1c57 100644
> --- a/net/bridge/br_input.c
> +++ b/net/bridge/br_input.c
> @@ -109,9 +109,18 @@ int br_handle_frame_finish(struct net *net,
> struct sock *sk, struct sk_buff *skb
>                 struct net_bridge_fdb_entry *fdb_src =
>                         br_fdb_find_rcu(br, eth_hdr(skb)->h_source, 
> vid);
> 
> -               if (!fdb_src || READ_ONCE(fdb_src->dst) != p ||
> -                   test_bit(BR_FDB_LOCAL, &fdb_src->flags))
> +               if (!fdb_src) {
> +                       if (p->flags & BR_PORT_MAB) {
> +                               __set_bit(BR_FDB_ENTRY_LOCKED, &flags);
> +                               br_fdb_update(br, p, 
> eth_hdr(skb)->h_source,
> +                                             vid, flags);
> +                       }
> +                       goto drop;
> +               } else if (READ_ONCE(fdb_src->dst) != p ||
> +                          test_bit(BR_FDB_LOCAL, &fdb_src->flags) ||
> +                          test_bit(BR_FDB_LOCKED, &fdb_src->flags)) {
>                         goto drop;
> +               }
>         }
> 
> The semantics are very clear, IMO. On FDB miss, add a locked FDB entry
> and drop the packet. On FDB mismatch, drop the packet.
> 
> Entry can roam from an unauthorized port to an authorized port, but not
> the other way around. Not sure what is the use case for allowing 
> roaming
> between unauthorized ports.
> 
> Note that with the above, locked entries are not refreshed and will
> therefore age out unless replaced by user space.
> 

Okay, I got the semantics (locked/unlocked vs unauthorized/authorized) 
reversed, so I will go with your suggestion.