linux-kernel - Re: [PATCH net-next 1/3] net: bridge: add fdb flag to extent locked port feature

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Date:   Tue, 15 Mar 2022 13:00:12 +0200
From:   Ido Schimmel <idosch@...sch.org>
To:     Hans Schultz <schultz.hans@...il.com>
Cc:     davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        Ivan Vecera <ivecera@...hat.com>,
        Roopa Prabhu <roopa@...dia.com>,
        Nikolay Aleksandrov <razor@...ckwall.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Ido Schimmel <idosch@...dia.com>, linux-kernel@...r.kernel.org,
        bridge@...ts.linux-foundation.org
Subject: Re: [PATCH net-next 1/3] net: bridge: add fdb flag to extent locked
 port feature

On Tue, Mar 15, 2022 at 09:48:52AM +0100, Hans Schultz wrote:
> On mån, mar 14, 2022 at 17:30, Ido Schimmel <idosch@...sch.org> wrote:
> > On Thu, Mar 10, 2022 at 03:23:18PM +0100, Hans Schultz wrote:
> >> @@ -94,8 +95,16 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
> >>  			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))
> >> +		    test_bit(BR_FDB_LOCAL, &fdb_src->flags)) {
> >> +			if (!fdb_src) {
> >> +				set_bit(BR_FDB_ENTRY_LOCKED, &flags);
> >
> > This flag is read-only for user space, right? That is, the kernel needs
> > to reject it during netlink policy validation.
> >
> 
> Yes, the flag is only readable from user space, unless there is a wish
> to change that.

OK, so please spell it out in the commit message so that it is clear the
flag can only be set by the kernel.