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

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Message-ID: <0eeaf59f-e7eb-7439-3c0a-17e7ac6741f0@blackwall.org>
Date:   Thu, 10 Mar 2022 16:42:51 +0200
From:   Nikolay Aleksandrov <razor@...ckwall.org>
To:     Hans Schultz <schultz.hans@...il.com>, davem@...emloft.net,
        kuba@...nel.org
Cc:     netdev@...r.kernel.org,
        Hans Schultz <schultz.hans+netdev@...il.com>,
        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>,
        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 10/03/2022 16:23, Hans Schultz wrote:
> Add an intermediate state for clients behind a locked port to allow for
> possible opening of the port for said clients. This feature corresponds
> to the Mac-Auth and MAC Authentication Bypass (MAB) named features. The
> latter defined by Cisco.
> 
> Signed-off-by: Hans Schultz <schultz.hans+netdev@...il.com>
> ---
>   include/uapi/linux/neighbour.h |  1 +
>   net/bridge/br_fdb.c            |  6 ++++++
>   net/bridge/br_input.c          | 11 ++++++++++-
>   net/bridge/br_private.h        |  3 ++-
>   4 files changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/include/uapi/linux/neighbour.h b/include/uapi/linux/neighbour.h
> index db05fb55055e..83115a592d58 100644
> --- a/include/uapi/linux/neighbour.h
> +++ b/include/uapi/linux/neighbour.h
> @@ -208,6 +208,7 @@ enum {
>   	NFEA_UNSPEC,
>   	NFEA_ACTIVITY_NOTIFY,
>   	NFEA_DONT_REFRESH,
> +	NFEA_LOCKED,
>   	__NFEA_MAX
>   };

Hmm, can you use NDA_FLAGS_EXT instead ?
That should simplify things and reduce the nl size.

>   #define NFEA_MAX (__NFEA_MAX - 1)
> diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
> index 6ccda68bd473..396dcf3084cf 100644
> --- a/net/bridge/br_fdb.c
> +++ b/net/bridge/br_fdb.c
> @@ -105,6 +105,7 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
>   	struct nda_cacheinfo ci;
>   	struct nlmsghdr *nlh;
>   	struct ndmsg *ndm;
> +	u8 ext_flags = 0;
>   
>   	nlh = nlmsg_put(skb, portid, seq, type, sizeof(*ndm), flags);
>   	if (nlh == NULL)
> @@ -125,11 +126,16 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
>   		ndm->ndm_flags |= NTF_EXT_LEARNED;
>   	if (test_bit(BR_FDB_STICKY, &fdb->flags))
>   		ndm->ndm_flags |= NTF_STICKY;
> +	if (test_bit(BR_FDB_ENTRY_LOCKED, &fdb->flags))
> +		ext_flags |= 1 << NFEA_LOCKED;
>   
>   	if (nla_put(skb, NDA_LLADDR, ETH_ALEN, &fdb->key.addr))
>   		goto nla_put_failure;
>   	if (nla_put_u32(skb, NDA_MASTER, br->dev->ifindex))
>   		goto nla_put_failure;
> +	if (nla_put_u8(skb, NDA_FDB_EXT_ATTRS, ext_flags))
> +		goto nla_put_failure;
> +
>   	ci.ndm_used	 = jiffies_to_clock_t(now - fdb->used);
>   	ci.ndm_confirmed = 0;
>   	ci.ndm_updated	 = jiffies_to_clock_t(now - fdb->updated);
> diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
> index e0c13fcc50ed..897908484b18 100644
> --- a/net/bridge/br_input.c
> +++ b/net/bridge/br_input.c
> @@ -75,6 +75,7 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
>   	struct net_bridge_mcast *brmctx;
>   	struct net_bridge_vlan *vlan;
>   	struct net_bridge *br;
> +	unsigned long flags = 0;

Please move this below...

>   	u16 vid = 0;
>   	u8 state;
>   
> @@ -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) {

... here where it's only used.

> +				set_bit(BR_FDB_ENTRY_LOCKED, &flags);
> +				br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, flags);
> +			}
>   			goto drop;
> +		} else {
> +			if (test_bit(BR_FDB_ENTRY_LOCKED, &fdb_src->flags))
> +				goto drop;
> +		}
>   	}
>   
>   	nbp_switchdev_frame_mark(p, skb);
> diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
> index 48bc61ebc211..f5a0b68c4857 100644
> --- a/net/bridge/br_private.h
> +++ b/net/bridge/br_private.h
> @@ -248,7 +248,8 @@ enum {
>   	BR_FDB_ADDED_BY_EXT_LEARN,
>   	BR_FDB_OFFLOADED,
>   	BR_FDB_NOTIFY,
> -	BR_FDB_NOTIFY_INACTIVE
> +	BR_FDB_NOTIFY_INACTIVE,
> +	BR_FDB_ENTRY_LOCKED,
>   };
>   
>   struct net_bridge_fdb_key {