kernel/linux.git/net/bridge/br_fdb.c, branch v6.3.2

bridge: switchdev: Allow device drivers to install locked FDB entries

2022-11-10T03:06:13+00:00

When the bridge is offloaded to hardware, FDB entries are learned and aged-out by the hardware. Some device drivers synchronize the hardware and software FDBs by generating switchdev events towards the bridge. When a port is locked, the hardware must not learn autonomously, as otherwise any host will blindly gain authorization. Instead, the hardware should generate events regarding hosts that are trying to gain authorization and their MAC addresses should be notified by the device driver as locked FDB entries towards the bridge driver. Allow device drivers to notify the bridge driver about such entries by extending the 'switchdev_notifier_fdb_info' structure with the 'locked' bit. The bit can only be set by device drivers and not by the bridge driver. Prevent a locked entry from being installed if MAB is not enabled on the bridge port. If an entry already exists in the bridge driver, reject the locked entry if the current entry does not have the "locked" flag set or if it points to a different port. The same semantics are implemented in the software data path. Signed-off-by: Hans J. Schultz Signed-off-by: Ido Schimmel Reviewed-by: Petr Machata Signed-off-by: Petr Machata Reviewed-by: Vladimir Oltean Acked-by: Nikolay Aleksandrov Signed-off-by: Jakub Kicinski

bridge: Add MAC Authentication Bypass (MAB) support

2022-11-04T03:46:32+00:00

Hosts that support 802.1X authentication are able to authenticate themselves by exchanging EAPOL frames with an authenticator (Ethernet bridge, in this case) and an authentication server. Access to the network is only granted by the authenticator to successfully authenticated hosts. The above is implemented in the bridge using the "locked" bridge port option. When enabled, link-local frames (e.g., EAPOL) can be locally received by the bridge, but all other frames are dropped unless the host is authenticated. That is, unless the user space control plane installed an FDB entry according to which the source address of the frame is located behind the locked ingress port. The entry can be dynamic, in which case learning needs to be enabled so that the entry will be refreshed by incoming traffic. There are deployments in which not all the devices connected to the authenticator (the bridge) support 802.1X. Such devices can include printers and cameras. One option to support such deployments is to unlock the bridge ports connecting these devices, but a slightly more secure option is to use MAB. When MAB is enabled, the MAC address of the connected device is used as the user name and password for the authentication. For MAB to work, the user space control plane needs to be notified about MAC addresses that are trying to gain access so that they will be compared against an allow list. This can be implemented via the regular learning process with the sole difference that learned FDB entries are installed with a new "locked" flag indicating that the entry cannot be used to authenticate the device. The flag cannot be set by user space, but user space can clear the flag by replacing the entry, thereby authenticating the device. Locked FDB entries implement the following semantics with regards to roaming, aging and forwarding: 1. Roaming: Locked FDB entries can roam to unlocked (authorized) ports, in which case the "locked" flag is cleared. FDB entries cannot roam to locked ports regardless of MAB being enabled or not. Therefore, locked FDB entries are only created if an FDB entry with the given {MAC, VID} does not already exist. This behavior prevents unauthenticated devices from disrupting traffic destined to already authenticated devices. 2. Aging: Locked FDB entries age and refresh by incoming traffic like regular entries. 3. Forwarding: Locked FDB entries forward traffic like regular entries. If user space detects an unauthorized MAC behind a locked port and wishes to prevent traffic with this MAC DA from reaching the host, it can do so using tc or a different mechanism. Enable the above behavior using a new bridge port option called "mab". It can only be enabled on a bridge port that is both locked and has learning enabled. Locked FDB entries are flushed from the port once MAB is disabled. A new option is added because there are pure 802.1X deployments that are not interested in notifications about locked FDB entries. Signed-off-by: Hans J. Schultz Signed-off-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Reviewed-by: Vladimir Oltean Signed-off-by: Jakub Kicinski

rtnetlink: add extack support in fdb del handlers

2022-05-09T10:58:20+00:00

Add extack support to .ndo_fdb_del in netdevice.h and all related methods. Signed-off-by: Alaa Mohamed Signed-off-by: David S. Miller

net: bridge: fdb: add support for flush filtering based on ifindex and vlan

2022-04-13T11:46:26+00:00

Add support for fdb flush filtering based on destination ifindex and vlan id. The ifindex must either match a port's device ifindex or the bridge's. The vlan support is trivial since it's already validated by rtnl_fdb_del, we just need to fill it in. Signed-off-by: Nikolay Aleksandrov Signed-off-by: David S. Miller

net: bridge: fdb: add support for flush filtering based on ndm flags and state

2022-04-13T11:46:26+00:00

Add support for fdb flush filtering based on ndm flags and state. NDM state and flags are mapped to bridge-specific flags and matched according to the specified masks. 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. Only allowed bits can be set, NTF_SELF and NTF_MASTER are ignored. Signed-off-by: Nikolay Aleksandrov Signed-off-by: David S. Miller

net: bridge: fdb: add support for fine-grained flushing

2022-04-13T11:46:26+00:00

Add the ability to specify exactly which fdbs to be flushed. They are described by a new structure - net_bridge_fdb_flush_desc. Currently it can match on port/bridge ifindex, vlan id and fdb flags. It is used to describe the existing dynamic fdb flush operation. Note that this flush operation doesn't treat permanent entries in a special way (fdb_delete vs fdb_delete_local), it will delete them regardless if any port is using them, so currently it can't directly replace deletes which need to handle that case, although we can extend it later for that too. Signed-off-by: Nikolay Aleksandrov Signed-off-by: David S. Miller

net: bridge: fdb: add ndo_fdb_del_bulk

2022-04-13T11:46:26+00:00

Add a minimal ndo_fdb_del_bulk implementation which flushes all entries. Support for more fine-grained filtering will be added in the following patches. Signed-off-by: Nikolay Aleksandrov Signed-off-by: David S. Miller

net: bridge: move br_fdb_replay inside br_switchdev.c

2021-10-27T13:54:02+00:00

br_fdb_replay is only called from switchdev code paths, so it makes sense to be disabled if switchdev is not enabled in the first place. As opposed to br_mdb_replay and br_vlan_replay which might be turned off depending on bridge support for multicast and VLANs, FDB support is always on. So moving br_mdb_replay and br_vlan_replay inside br_switchdev.c would mean adding some #ifdef's in br_switchdev.c, so we keep those where they are. The reason for the movement is that in future changes there will be some code reuse between br_switchdev_fdb_notify and br_fdb_replay. Signed-off-by: Vladimir Oltean Reviewed-by: Ido Schimmel Signed-off-by: David S. Miller

net: bridge: reduce indentation level in fdb_create

2021-10-27T13:54:02+00:00

We can express the same logic without an "if" condition as big as the function, just return early if the kmem_cache_alloc() call fails. Signed-off-by: Vladimir Oltean Reviewed-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Signed-off-by: David S. Miller

net: bridge: rename br_fdb_insert to br_fdb_add_local

2021-10-27T13:54:02+00:00

br_fdb_insert() is a wrapper over fdb_insert() that also takes the bridge hash_lock. With fdb_insert() being renamed to fdb_add_local(), rename br_fdb_insert() to br_fdb_add_local(). Signed-off-by: Vladimir Oltean Reviewed-by: Ido Schimmel Acked-by: Nikolay Aleksandrov Signed-off-by: David S. Miller