On Thu, Apr 11, 2019 at 3:23 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote: > > Hey Stanislav, > > On 04/09/2019 08:49 PM, Stanislav Fomichev wrote: > > Add new set of arguments to bpf_attr for BPF_PROG_TEST_RUN: > > * ctx_in/ctx_size_in - input context > > * ctx_out/ctx_size_out - output context > > > > The intended use case is to pass some meta data to the test runs that > > operate on skb (this has being brought up on recent LPC). > > > > For programs that use bpf_prog_test_run_skb, support __sk_buff input and > > output. Initially, from input __sk_buff, copy _only_ cb and priority into > > skb, all other non-zero fields are prohibited (with EINVAL). > > If the user has set ctx_out/ctx_size_out, copy the potentially modified > > __sk_buff back to the userspace. > > > > We require all fields of input __sk_buff except the ones we explicitly > > support to be set to zero. The expectation is that in the future we might > > add support for more fields and we want to fail explicitly if the user > > runs the program on the kernel where we don't yet support them. > > > > The API is intentionally vague (i.e. we don't explicitly add __sk_buff > > to bpf_attr, but ctx_in) to potentially let other test_run types use > > this interface in the future (this can be xdp_md for xdp types for > > example). > > > > v4: > > * don't copy more than allowed in bpf_ctx_init [Martin] > > > > v3: > > * handle case where ctx_in is NULL, but ctx_out is not [Martin] > > * convert size==0 checks to ptr==NULL checks and add some extra ptr > > checks [Martin] > > > > v2: > > * Addressed comments from Martin Lau > > > > Cc: Martin Lau <kafai@xxxxxx> > > Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx> > > This still has a bug in that we need to reject !bpf_prog_test_run_skb() cases, > since they are not handled by your set. So for e.g. XDP, flow dissector progs, > we need to error out if ctx is set such that it can be safely extended in future. > Please follow up. Good point, sure, will follow up on that! > Thanks, > Daniel
