Re: [PATCH net-next 4/6] net: bridge: fdb: add support for flush filtering based on ndm flags and state

[Ido Schimmel <idosch@idosch.org>]

On Sat, Apr 09, 2022 at 01:58:55PM +0300, Nikolay Aleksandrov wrote:
> Add support for fdb flush filtering based on ndm flags and state. The
> new attributes allow users to specify a mask and value which are mapped
> to bridge-specific flags. NTF_USE is used to represent added_by_user
> flag since it sets it on fdb add and we don't have a 1:1 mapping for it.
> 
> Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org>
> ---
>  include/uapi/linux/if_bridge.h |  4 +++
>  net/bridge/br_fdb.c            | 55 ++++++++++++++++++++++++++++++++++
>  2 files changed, 59 insertions(+)
> 
> diff --git a/include/uapi/linux/if_bridge.h b/include/uapi/linux/if_bridge.h
> index 2f3799cf14b2..4638d7e39f2a 100644
> --- a/include/uapi/linux/if_bridge.h
> +++ b/include/uapi/linux/if_bridge.h
> @@ -815,6 +815,10 @@ enum {
>  /* embedded in BRIDGE_FLUSH_FDB */
>  enum {
>  	FDB_FLUSH_UNSPEC,
> +	FDB_FLUSH_NDM_STATE,
> +	FDB_FLUSH_NDM_STATE_MASK,
> +	FDB_FLUSH_NDM_FLAGS,
> +	FDB_FLUSH_NDM_FLAGS_MASK,
>  	__FDB_FLUSH_MAX
>  };
>  #define FDB_FLUSH_MAX (__FDB_FLUSH_MAX - 1)
> diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
> index 62f694a739e1..340a2ace1d5e 100644
> --- a/net/bridge/br_fdb.c
> +++ b/net/bridge/br_fdb.c
> @@ -594,8 +594,40 @@ void br_fdb_flush(struct net_bridge *br,
>  	rcu_read_unlock();
>  }
>  
> +static unsigned long __ndm_state_to_fdb_flags(u16 ndm_state)
> +{
> +	unsigned long flags = 0;
> +
> +	if (ndm_state & NUD_PERMANENT)
> +		__set_bit(BR_FDB_LOCAL, &flags);
> +	if (ndm_state & NUD_NOARP)
> +		__set_bit(BR_FDB_STATIC, &flags);
> +
> +	return flags;
> +}
> +
> +static unsigned long __ndm_flags_to_fdb_flags(u16 ndm_flags)
> +{
> +	unsigned long flags = 0;
> +
> +	if (ndm_flags & NTF_USE)
> +		__set_bit(BR_FDB_ADDED_BY_USER, &flags);
> +	if (ndm_flags & NTF_EXT_LEARNED)
> +		__set_bit(BR_FDB_ADDED_BY_EXT_LEARN, &flags);
> +	if (ndm_flags & NTF_OFFLOADED)
> +		__set_bit(BR_FDB_OFFLOADED, &flags);
> +	if (ndm_flags & NTF_STICKY)
> +		__set_bit(BR_FDB_STICKY, &flags);
> +
> +	return flags;
> +}
> +
>  static const struct nla_policy br_fdb_flush_policy[FDB_FLUSH_MAX + 1] = {
>  	[FDB_FLUSH_UNSPEC]	= { .type = NLA_REJECT },
> +	[FDB_FLUSH_NDM_STATE]	= { .type = NLA_U16 },
> +	[FDB_FLUSH_NDM_FLAGS]	= { .type = NLA_U16 },
> +	[FDB_FLUSH_NDM_STATE_MASK]	= { .type = NLA_U16 },
> +	[FDB_FLUSH_NDM_FLAGS_MASK]	= { .type = NLA_U16 },

Might be better to use NLA_POLICY_MASK(NLA_U16, mask) and reject
unsupported states / flags instead of just ignoring them?

>  };
>  
>  int br_fdb_flush_nlattr(struct net_bridge *br, struct nlattr *fdb_flush_attr,
> @@ -610,6 +642,29 @@ int br_fdb_flush_nlattr(struct net_bridge *br, struct nlattr *fdb_flush_attr,
>  	if (err)
>  		return err;
>  
> +	if (fdb_flush_tb[FDB_FLUSH_NDM_STATE]) {
> +		u16 ndm_state = nla_get_u16(fdb_flush_tb[FDB_FLUSH_NDM_STATE]);
> +
> +		desc.flags |= __ndm_state_to_fdb_flags(ndm_state);
> +	}
> +	if (fdb_flush_tb[FDB_FLUSH_NDM_STATE_MASK]) {
> +		u16 ndm_state_mask;
> +
> +		ndm_state_mask = nla_get_u16(fdb_flush_tb[FDB_FLUSH_NDM_STATE_MASK]);
> +		desc.flags_mask |= __ndm_state_to_fdb_flags(ndm_state_mask);
> +	}
> +	if (fdb_flush_tb[FDB_FLUSH_NDM_FLAGS]) {
> +		u16 ndm_flags = nla_get_u16(fdb_flush_tb[FDB_FLUSH_NDM_FLAGS]);
> +
> +		desc.flags |= __ndm_flags_to_fdb_flags(ndm_flags);
> +	}
> +	if (fdb_flush_tb[FDB_FLUSH_NDM_FLAGS_MASK]) {
> +		u16 ndm_flags_mask;
> +
> +		ndm_flags_mask = nla_get_u16(fdb_flush_tb[FDB_FLUSH_NDM_FLAGS_MASK]);
> +		desc.flags_mask |= __ndm_flags_to_fdb_flags(ndm_flags_mask);
> +	}
> +
>  	br_debug(br, "flushing port ifindex: %d vlan id: %u flags: 0x%lx flags mask: 0x%lx\n",
>  		 desc.port_ifindex, desc.vlan_id, desc.flags, desc.flags_mask);
>  
> -- 
> 2.35.1
>