Re: [PATCH bpf-next v6 1/7] net: bonding: Refactor bond_xmit_hash for use with xdp_buff

On 8/11/21 4:22 AM, Jussi Maki wrote:

Hi Jonathan,

Thanks for catching this. You're right, this will NULL deref if XDP
bonding is used with the VLAN_SRCMAC xmit policy. I think what
happened was that a very early version restricted the xmit policies
that were applicable, but it got dropped when this was refactored.
I'll look into this today and will add in support (or refuse) the
VLAN_SRCMAC xmit policy and extend the tests to cover this.

In support of some customer requests and to stop adding more and more 
hashing policies I was looking at adding a custom policy that exposes a 
bitfield so userspace can select which header items should be included 
in the hash. I was looking at a flow dissector implementation to parse 
the packet and then generate the hash from the flow data pulled. It 
looks like the outer hashing functions as they exist now, 
bond_xmit_hash() and bond_xmit_hash_xdp(), could make the correctly 
formatted call to __skb_flow_dissect(). We would then pass around the 
resultant struct flow_keys, or bonding specific one to add MAC header 
parsing support, and it appears we could avoid making the actual hashing 
functions know if they need to hash an sk_buff vs xdp_buff. What do you 
think?

-Jon