On Thu, Mar 10, 2022 at 03:23:18PM +0100, 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@xxxxxxxxx>
> ---
> 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
> };
> #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;
> 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) {
> + 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.
> + br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, flags);
> + }
> goto drop;
> + } else {
IIUC, we get here in case there is a non-local FDB entry with the SA
that points to our port. Can you write it as:
if (!fdb_src || READ_ONCE(fdb_src->dst) != p ||
test_bit(BR_FDB_LOCAL, &fdb_src->flags) ||
test_bit(BR_FDB_ENTRY_LOCKED, &fdb_src->flags)) {
if (!fdb_src) {
...
}
goto drop;
}
> + 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 {
> --
> 2.30.2
>
