When we create an L2 loop on a bridge in netns, we will see packets storm
even if STP is enabled.
# unshare -n
# ip link add br0 type bridge
# ip link add veth0 type veth peer name veth1
# ip link set veth0 master br0 up
# ip link set veth1 master br0 up
# ip link set br0 type bridge stp_state 1
# ip link set br0 up
# sleep 30
# ip -s link show br0
2: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP mode DEFAULT group default qlen 1000
link/ether b6:61:98:1c:1c:b5 brd ff:ff:ff:ff:ff:ff
RX: bytes packets errors dropped missed mcast
956553768 12861249 0 0 0 12861249 <-. Keep
TX: bytes packets errors dropped carrier collsns | increasing
1027834 11951 0 0 0 0 <-' rapidly
This is because llc_rcv() drops all packets in non-root netns and BPDU
is dropped.
Let's add extack warning when enabling STP in netns.
# unshare -n
# ip link add br0 type bridge
# ip link set br0 type bridge stp_state 1
Warning: bridge: STP does not work in non-root netns.
Note this commit will be reverted later when we namespacify the whole LLC
infra.
Fixes: e730c15519 ("[NET]: Make packet reception network namespace safe")
Suggested-by: Harry Coin <hcoin@quietfountain.com>
Link: https://lore.kernel.org/netdev/0f531295-e289-022d-5add-5ceffa0df9bc@quietfountain.com/
Suggested-by: Ido Schimmel <idosch@idosch.org>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
56a16035bb