Vladimir Oltean cc1939e4b3 net: dsa: Allow drivers to filter packets they can decode source port from ... Frames get processed by DSA and redirected to switch port net devices based on the ETH_P_XDSA multiplexed packet_type handler found by the network stack when calling eth_type_trans(). The running assumption is that once the DSA .rcv function is called, DSA is always able to decode the switch tag in order to change the skb->dev from its master. However there are tagging protocols (such as the new DSA_TAG_PROTO_SJA1105, user of DSA_TAG_PROTO_8021Q) where this assumption is not completely true, since switch tagging piggybacks on the absence of a vlan_filtering bridge. Moreover, management traffic (BPDU, PTP) for this switch doesn't rely on switch tagging, but on a different mechanism. So it would make sense to at least be able to terminate that. Having DSA receive traffic it can't decode would put it in an impossible situation: the eth_type_trans() function would invoke the DSA .rcv(), which could not change skb->dev, then eth_type_trans() would be invoked again, which again would call the DSA .rcv, and the packet would never be able to exit the DSA filter and would spiral in a loop until the whole system dies. This happens because eth_type_trans() doesn't actually look at the skb (so as to identify a potential tag) when it deems it as being ETH_P_XDSA. It just checks whether skb->dev has a DSA private pointer installed (therefore it's a DSA master) and that there exists a .rcv callback (everybody except DSA_TAG_PROTO_NONE has that). This is understandable as there are many switch tags out there, and exhaustively checking for all of them is far from ideal. The solution lies in introducing a filtering function for each tagging protocol. In the absence of a filtering function, all traffic is passed to the .rcv DSA callback. The tagging protocol should see the filtering function as a pre-validation that it can decode the incoming skb. The traffic that doesn't match the filter will bypass the DSA .rcv callback and be left on the master netdevice, which wasn't previously possible. Signed-off-by: Vladimir Oltean <olteanv@gmail.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2019-05-05 21:52:42 -07:00
..
eth.c	net: dsa: Allow drivers to filter packets they can decode source port from	2019-05-05 21:52:42 -07:00
Makefile	ipx: move peII functions	2012-07-19 10:48:00 -07:00