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    SubjectRe: [PATCH v2 net-next 1/4] net: bridge: add fdb flag to extent locked port feature
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    On 17/03/2022 11:38, 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.
    > Only the kernel can set this FDB entry flag, while userspace can read
    > the flag and remove it by deleting the FDB entry.
    >
    > Signed-off-by: Hans Schultz <schultz.hans+netdev@gmail.com>
    > ---
    > include/uapi/linux/neighbour.h | 1 +
    > net/bridge/br_fdb.c | 6 ++++++
    > net/bridge/br_input.c | 10 +++++++++-
    > net/bridge/br_private.h | 3 ++-
    > 4 files changed, 18 insertions(+), 2 deletions(-)
    >
    > diff --git a/include/uapi/linux/neighbour.h b/include/uapi/linux/neighbour.h
    > index db05fb55055e..a2df3b9b2f68 100644
    > --- a/include/uapi/linux/neighbour.h
    > +++ b/include/uapi/linux/neighbour.h
    > @@ -51,6 +51,7 @@ enum {
    > #define NTF_ROUTER (1 << 7)
    > /* Extended flags under NDA_FLAGS_EXT: */
    > #define NTF_EXT_MANAGED (1 << 0)
    > +#define NTF_EXT_LOCKED (1 << 1)
    >
    > /*
    > * Neighbor Cache Entry States.
    > diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
    > index 6ccda68bd473..57ec559a85a7 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;

    Let's not limit ourselves to 8 bits only for new flags, we'll need to extend them
    very soon. The neigh code defines the attribute as u32 which seems more appropriate.

    >
    > 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 |= NTF_EXT_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_FLAGS_EXT, ext_flags))
    > + goto nla_put_failure;
    > +

    You have to account for the new attribute size in fdb_nlmsg_size().

    > 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..5ef25a496806 100644
    > --- a/net/bridge/br_input.c
    > +++ b/net/bridge/br_input.c
    > @@ -94,8 +94,16 @@ 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) ||
    > + test_bit(BR_FDB_ENTRY_LOCKED, &fdb_src->flags)) {
    > + if (!fdb_src) {
    > + unsigned long flags = 0;
    > +
    > + set_bit(BR_FDB_ENTRY_LOCKED, &flags);

    __set_bit()

    > + br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 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 {

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