From: Kuniyuki Iwashima kuniyu@amazon.com
[ Upstream commit 56a16035bb6effb37177867cea94c13a8382f745 ]
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: e730c15519d0 ("[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@quietfou... 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 Signed-off-by: Sasha Levin sashal@kernel.org --- net/bridge/br_stp_if.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/net/bridge/br_stp_if.c b/net/bridge/br_stp_if.c index 75204d36d7f90..b65962682771f 100644 --- a/net/bridge/br_stp_if.c +++ b/net/bridge/br_stp_if.c @@ -201,6 +201,9 @@ int br_stp_set_enabled(struct net_bridge *br, unsigned long val, { ASSERT_RTNL();
+ if (!net_eq(dev_net(br->dev), &init_net)) + NL_SET_ERR_MSG_MOD(extack, "STP does not work in non-root netns"); + if (br_mrp_enabled(br)) { NL_SET_ERR_MSG_MOD(extack, "STP can't be enabled if MRP is already enabled");