kernel.git/net/bridge/br_fdb.c, branch linux-5.14.y

net: bridge: fix flags interpretation for extern learn fdb entries

2021-08-10T18:29:39Z

Ignore fdb flags when adding port extern learn entries and always set BR_FDB_LOCAL flag when adding bridge extern learn entries. This is closest to the behaviour we had before and avoids breaking any use cases which were allowed. This patch fixes iproute2 calls which assume NUD_PERMANENT and were allowed before, example: $ bridge fdb add 00:11:22:33:44:55 dev swp1 extern_learn Extern learn entries are allowed to roam, but do not expire, so static or dynamic flags make no sense for them. Also add a comment for future reference. Fixes: eb100e0e24a2 ("net: bridge: allow to add externally learned entries from user-space") Fixes: 0541a6293298 ("net: bridge: validate the NUD_PERMANENT bit when adding an extern_learn FDB entry") Reviewed-by: Ido Schimmel Tested-by: Ido Schimmel Signed-off-by: Nikolay Aleksandrov Reviewed-by: Vladimir Oltean Link: https://lore.kernel.org/r/20210810110010.43859-1-razor@blackwall.org Signed-off-by: Jakub Kicinski

net: bridge: validate the NUD_PERMANENT bit when adding an extern_learn FDB entry

2021-08-02T22:00:48Z

Currently it is possible to add broken extern_learn FDB entries to the bridge in two ways: 1. Entries pointing towards the bridge device that are not local/permanent: ip link add br0 type bridge bridge fdb add 00:01:02:03:04:05 dev br0 self extern_learn static 2. Entries pointing towards the bridge device or towards a port that are marked as local/permanent, however the bridge does not process the 'permanent' bit in any way, therefore they are recorded as though they aren't permanent: ip link add br0 type bridge bridge fdb add 00:01:02:03:04:05 dev br0 self extern_learn permanent Since commit 52e4bec15546 ("net: bridge: switchdev: treat local FDBs the same as entries towards the bridge"), these incorrect FDB entries can even trigger NULL pointer dereferences inside the kernel. This is because that commit made the assumption that all FDB entries that are not local/permanent have a valid destination port. For context, local / permanent FDB entries either have fdb->dst == NULL, and these point towards the bridge device and are therefore local and not to be used for forwarding, or have fdb->dst == a net_bridge_port structure (but are to be treated in the same way, i.e. not for forwarding). That assumption _is_ correct as long as things are working correctly in the bridge driver, i.e. we cannot logically have fdb->dst == NULL under any circumstance for FDB entries that are not local. However, the extern_learn code path where FDB entries are managed by a user space controller show that it is possible for the bridge kernel driver to misinterpret the NUD flags of an entry transmitted by user space, and end up having fdb->dst == NULL while not being a local entry. This is invalid and should be rejected. Before, the two commands listed above both crashed the kernel in this check from br_switchdev_fdb_notify: struct net_device *dev = info.is_local ? br->dev : dst->dev; info.is_local == false, dst == NULL. After this patch, the invalid entry added by the first command is rejected: ip link add br0 type bridge && bridge fdb add 00:01:02:03:04:05 dev br0 self extern_learn static; ip link del br0 Error: bridge: FDB entry towards bridge must be permanent. and the valid entry added by the second command is properly treated as a local address and does not crash br_switchdev_fdb_notify anymore: ip link add br0 type bridge && bridge fdb add 00:01:02:03:04:05 dev br0 self extern_learn permanent; ip link del br0 Fixes: eb100e0e24a2 ("net: bridge: allow to add externally learned entries from user-space") Reported-by: syzbot+9ba1174359adba5a5b7c@syzkaller.appspotmail.com Signed-off-by: Vladimir Oltean Acked-by: Nikolay Aleksandrov Link: https://lore.kernel.org/r/20210801231730.7493-1-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski

net: bridge: do not replay fdb entries pointing towards the bridge twice

2021-07-20T11:08:45Z

This simple script: ip link add br0 type bridge ip link set swp2 master br0 ip link set br0 address 00:01:02:03:04:05 ip link del br0 produces this result on a DSA switch: [ 421.306399] br0: port 1(swp2) entered blocking state [ 421.311445] br0: port 1(swp2) entered disabled state [ 421.472553] device swp2 entered promiscuous mode [ 421.488986] device swp2 left promiscuous mode [ 421.493508] br0: port 1(swp2) entered disabled state [ 421.886107] sja1105 spi0.1: port 1 failed to delete 00:01:02:03:04:05 vid 1 from fdb: -ENOENT [ 421.894374] sja1105 spi0.1: port 1 failed to delete 00:01:02:03:04:05 vid 0 from fdb: -ENOENT [ 421.943982] br0: port 1(swp2) entered blocking state [ 421.949030] br0: port 1(swp2) entered disabled state [ 422.112504] device swp2 entered promiscuous mode A very simplified view of what happens is: (1) the bridge port is created, and the bridge device inherits its MAC address (2) when joining, the bridge port (DSA) requests a replay of the addition of all FDB entries towards this bridge port and towards the bridge device itself. In fact, DSA calls br_fdb_replay() twice: br_fdb_replay(br, brport_dev); br_fdb_replay(br, br); DSA uses reference counting for the FDB entries. So the MAC address of the bridge is simply kept with refcount 2. When the bridge port leaves under normal circumstances, everything cancels out since the replay of the FDB entry deletion is also done twice per VLAN. (3) when the bridge MAC address changes, switchdev is notified of the deletion of the old address and of the insertion of the new one. But the old address does not really go away, since it had refcount 2, and the new address is added "only" with refcount 1. (4) when the bridge port leaves now, it will replay a deletion of the FDB entries pointing towards the bridge twice. Then DSA will complain that it can't delete something that no longer exists. It is clear that the problem is that the FDB entries towards the bridge are replayed too many times, so let's fix that problem. Fixes: 63c51453c82c ("net: dsa: replay the local bridge FDB entries pointing to the bridge dev too") Signed-off-by: Vladimir Oltean Link: https://lore.kernel.org/r/20210719093916.4099032-1-vladimir.oltean@nxp.com Signed-off-by: Jakub Kicinski

net: bridge: allow br_fdb_replay to be called for the bridge device

2021-06-29T17:46:23Z

When a port joins a bridge which already has local FDB entries pointing to the bridge device itself, we would like to offload those, so allow the "dev" argument to be equal to the bridge too. The code already does what we need in that case. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: bridge: switchdev: send FDB notifications for host addresses

2021-06-29T17:46:23Z

Treat addresses added to the bridge itself in the same way as regular ports and send out a notification so that drivers may sync it down to the hardware FDB. Signed-off-by: Tobias Waldekranz Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: bridge: use READ_ONCE() and WRITE_ONCE() compiler barriers for fdb->dst

2021-06-29T17:46:22Z

Annotate the writer side of fdb->dst: - fdb_create() - br_fdb_update() - fdb_add_entry() - br_fdb_external_learn_add() with WRITE_ONCE() and the reader side: - br_fdb_test_addr() - br_fdb_update() - fdb_fill_info() - fdb_add_entry() - fdb_delete_by_addr_and_port() - br_fdb_external_learn_add() - br_switchdev_fdb_notify() with compiler barriers such that the readers do not attempt to reload fdb->dst multiple times, leading to potentially different destination ports when the fdb entry is updated concurrently. This is especially important in read-side sections where fdb->dst is used more than once, but let's convert all accesses for the sake of uniformity. Suggested-by: Nikolay Aleksandrov Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: bridge: allow the switchdev replay functions to be called for deletion

2021-06-28T21:09:03Z

When a switchdev port leaves a LAG that is a bridge port, the switchdev objects and port attributes offloaded to that port are not removed: ip link add br0 type bridge ip link add bond0 type bond mode 802.3ad ip link set swp0 master bond0 ip link set bond0 master br0 bridge vlan add dev bond0 vid 100 ip link set swp0 nomaster VLAN 100 will remain installed on swp0 despite it going into standalone mode, because as far as the bridge is concerned, nothing ever happened to its bridge port. Let's extend the bridge vlan, fdb and mdb replay functions to take a 'bool adding' argument, and make DSA and ocelot call the replay functions with 'adding' as false from the switchdev unsync path, for the switch port that leaves the bridge. Note that this patch in itself does not salvage anything, because in the current pull mode of operation, DSA still needs to call the replay helpers with adding=false. This will be done in another patch. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: bridge: constify variables in the replay helpers

2021-06-28T21:09:03Z

Some of the arguments and local variables for the newly added switchdev replay helpers can be const, so let's make them so. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: bridge: ignore switchdev events for LAG ports which didn't request replay

2021-06-28T21:09:03Z

There is a slight inconvenience in the switchdev replay helpers added recently, and this is when: ip link add br0 type bridge ip link add bond0 type bond ip link set bond0 master br0 bridge vlan add dev bond0 vid 100 ip link set swp0 master bond0 ip link set swp1 master bond0 Since the underlying driver (currently only DSA) asks for a replay of VLANs when swp0 and swp1 join the LAG because it is bridged, what will happen is that DSA will try to react twice on the VLAN event for swp0. This is not really a huge problem right now, because most drivers accept duplicates since the bridge itself does, but it will become a problem when we add support for replaying switchdev object deletions. Let's fix this by adding a blank void *ctx in the replay helpers, which will be passed on by the bridge in the switchdev notifications. If the context is NULL, everything is the same as before. But if the context is populated with a valid pointer, the underlying switchdev driver (currently DSA) can use the pointer to 'see through' the bridge port (which in the example above is bond0) and 'know' that the event is only for a particular physical port offloading that bridge port, and not for all of them. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: bridge: include the is_local bit in br_fdb_replay

2021-06-28T21:09:03Z

Since commit 2c4eca3ef716 ("net: bridge: switchdev: include local flag in FDB notifications"), the bridge emits SWITCHDEV_FDB_ADD_TO_DEVICE events with the is_local flag populated (but we ignore it nonetheless). We would like DSA to start treating this bit, but it is still not populated by the replay helper, so add it there too. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller