Re: [PATCH net-next 1/4] net: bridge: Add support for bridge port in locked mode

Hans Schultz
2022-02-08T11:27:56Z

On mån, feb 07, 2022 at 12:49, Ido Schimmel <idosch@idosch.org> wrote:
> On Mon, Feb 07, 2022 at 11:07:39AM +0100, Hans Schultz wrote:
>> In a 802.1X scenario, clients connected to a bridge port shall not
>> be allowed to have traffic forwarded until fully authenticated.
>> A static fdb entry of the clients MAC address for the bridge port
>> unlocks the client and allows bidirectional communication.
>>
>> This scenario is facilitated with setting the bridge port in locked
>> mode, which is also supported by various switchcore chipsets.
>>
>> Signed-off-by: Hans Schultz <schultz.hans+netdev@gmail.com>
>> ---
>> include/linux/if_bridge.h | 1 +
>> include/uapi/linux/if_link.h | 1 +
>> net/bridge/br_input.c | 10 +++++++++-
>> net/bridge/br_netlink.c | 6 +++++-
>> 4 files changed, 16 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/if_bridge.h b/include/linux/if_bridge.h
>> index 509e18c7e740..3aae023a9353 100644
>> --- a/include/linux/if_bridge.h
>> +++ b/include/linux/if_bridge.h
>> @@ -58,6 +58,7 @@ struct br_ip_list {
>> #define BR_MRP_LOST_CONT BIT(18)
>> #define BR_MRP_LOST_IN_CONT BIT(19)
>> #define BR_TX_FWD_OFFLOAD BIT(20)
>> +#define BR_PORT_LOCKED BIT(21)
>>
>> #define BR_DEFAULT_AGEING_TIME (300 * HZ)
>>
>> diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
>> index 6218f93f5c1a..8fa2648fbc83 100644
>> --- a/include/uapi/linux/if_link.h
>> +++ b/include/uapi/linux/if_link.h
>> @@ -532,6 +532,7 @@ enum {
>> IFLA_BRPORT_GROUP_FWD_MASK,
>> IFLA_BRPORT_NEIGH_SUPPRESS,
>> IFLA_BRPORT_ISOLATED,
>> + IFLA_BRPORT_LOCKED,
>
> Please add it at the end to avoid breaking uAPI
>

Shall do.

>> IFLA_BRPORT_BACKUP_PORT,
>> IFLA_BRPORT_MRP_RING_OPEN,
>> IFLA_BRPORT_MRP_IN_OPEN,
>> diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
>> index b50382f957c1..469e3adbce07 100644
>> --- a/net/bridge/br_input.c
>> +++ b/net/bridge/br_input.c
>> @@ -69,6 +69,7 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
>> struct net_bridge_port *p = br_port_get_rcu(skb->dev);
>> enum br_pkt_type pkt_type = BR_PKT_UNICAST;
>> struct net_bridge_fdb_entry *dst = NULL;
>> + struct net_bridge_fdb_entry *fdb_entry;
>> struct net_bridge_mcast_port *pmctx;
>> struct net_bridge_mdb_entry *mdst;
>> bool local_rcv, mcast_hit = false;
>> @@ -81,6 +82,8 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
>> if (!p || p->state == BR_STATE_DISABLED)
>> goto drop;
>>
>> + br = p->br;
>> +
>> brmctx = &p->br->multicast_ctx;
>> pmctx = &p->multicast_ctx;
>> state = p->state;
>> @@ -88,10 +91,15 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
>> &state, &vlan))
>> goto out;
>>
>> + if (p->flags & BR_PORT_LOCKED) {
>> + fdb_entry = br_fdb_find_rcu(br, eth_hdr(skb)->h_source, vid);
>> + if (!(fdb_entry && fdb_entry->dst == p))
>> + goto drop;
>
> I'm not familiar with 802.1X so I have some questions:
>
> 1. Do we need to differentiate between no FDB entry and an FDB entry
> pointing to a different port than we expect?
>
> 2. Does user space care about SAs that did not pass the check? That is,
> does it need to see notifications? Counters?
>

2. As of now there are no counters, notifications on a locked port.

>> + }
>> +
>> nbp_switchdev_frame_mark(p, skb);
>>
>> /* insert into forwarding database after filtering to avoid spoofing */
>> - br = p->br;
>> if (p->flags & BR_LEARNING)
>> br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0);
>>
>> diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
>> index 2ff83d84230d..7d4432ca9a20 100644
>> --- a/net/bridge/br_netlink.c
>> +++ b/net/bridge/br_netlink.c
>> @@ -184,6 +184,7 @@ static inline size_t br_port_info_size(void)
>> + nla_total_size(1) /* IFLA_BRPORT_VLAN_TUNNEL */
>> + nla_total_size(1) /* IFLA_BRPORT_NEIGH_SUPPRESS */
>> + nla_total_size(1) /* IFLA_BRPORT_ISOLATED */
>> + + nla_total_size(1) /* IFLA_BRPORT_LOCKED */
>> + nla_total_size(sizeof(struct ifla_bridge_id)) /* IFLA_BRPORT_ROOT_ID */
>> + nla_total_size(sizeof(struct ifla_bridge_id)) /* IFLA_BRPORT_BRIDGE_ID */
>> + nla_total_size(sizeof(u16)) /* IFLA_BRPORT_DESIGNATED_PORT */
>> @@ -269,7 +270,8 @@ static int br_port_fill_attrs(struct sk_buff *skb,
>> BR_MRP_LOST_CONT)) ||
>> nla_put_u8(skb, IFLA_BRPORT_MRP_IN_OPEN,
>> !!(p->flags & BR_MRP_LOST_IN_CONT)) ||
>> - nla_put_u8(skb, IFLA_BRPORT_ISOLATED, !!(p->flags & BR_ISOLATED)))
>> + nla_put_u8(skb, IFLA_BRPORT_ISOLATED, !!(p->flags & BR_ISOLATED)) ||
>> + nla_put_u8(skb, IFLA_BRPORT_LOCKED, !!(p->flags & BR_PORT_LOCKED)))
>> return -EMSGSIZE;
>>
>> timerval = br_timer_value(&p->message_age_timer);
>> @@ -827,6 +829,7 @@ static const struct nla_policy br_port_policy[IFLA_BRPORT_MAX + 1] = {
>> [IFLA_BRPORT_GROUP_FWD_MASK] = { .type = NLA_U16 },
>> [IFLA_BRPORT_NEIGH_SUPPRESS] = { .type = NLA_U8 },
>> [IFLA_BRPORT_ISOLATED] = { .type = NLA_U8 },
>> + [IFLA_BRPORT_LOCKED] = { .type = NLA_U8 },
>> [IFLA_BRPORT_BACKUP_PORT] = { .type = NLA_U32 },
>> [IFLA_BRPORT_MCAST_EHT_HOSTS_LIMIT] = { .type = NLA_U32 },
>> };
>> @@ -893,6 +896,7 @@ static int br_setport(struct net_bridge_port *p, struct nlattr *tb[],
>> br_set_port_flag(p, tb, IFLA_BRPORT_VLAN_TUNNEL, BR_VLAN_TUNNEL);
>> br_set_port_flag(p, tb, IFLA_BRPORT_NEIGH_SUPPRESS, BR_NEIGH_SUPPRESS);
>> br_set_port_flag(p, tb, IFLA_BRPORT_ISOLATED, BR_ISOLATED);
>> + br_set_port_flag(p, tb, IFLA_BRPORT_LOCKED, BR_PORT_LOCKED);
>>
>> changed_mask = old_flags ^ p->flags;
>>
>> --
>> 2.30.2
>>