On May 19, 2020, at 22:13, Ariel Levkovich <lariel@xxxxxxxxxxxx> wrote: > > Hi Daniel, Aleksei > > I’m working on a feature to add support for datapath hash actions and matching via TC API. > > One of the options we want to offer users there is to provide their own hash calculation function, in the form of a BPF program. > The program should accept struct __sk_buff and return a hash value. > > After a little research and testing I noticed that some key parameters in struct __sk_buff are sertricted to BPF_PROG_TYPE_SK_SKB program types while I was planning to re-use the existing BPF_PROG_TYPE_SCHED_ACT program type for the act_hash purpose. > The key parameters I’m referring to are fields like remote_ip4, local_ip4, src/dst_port (flow key fields) that are most likely going to be relevant for hash calculation on a packet. > > So my question to you is basically what is the best option here? The way I see it the options are: > 1. Remove restrictions on these fields for SCHED_ACT program type in kernel/bpf/verifier.c > 2. Add new program type SCHED_ACT_HASH with permission to access these fields. > 3. More of a question - is there another way to access the flow keys via struct __sk_buff? > > Appreciate your advice and thanks in advance. > > Best Regards, > > Ariel Levkovich > Staff engineer, Mellanox SW Forgot to CC relevant mailing list. After further digging it seems there’s a pointer to a flow keys struct that is not restricted to SK_SKB prog types and should be our best option. The question remains whether we can reuse SCHED_ACT type or a new type for hash calculation should be added?
