Re: [PATCH bpf-next v5 4/9] tools: bpftool: add probes for eBPF program types

2019-01-23 23:44 UTC+0000 ~ Andrey Ignatov [off-list ref]

Quentin Monnet [off-list ref] [Thu, 2019-01-17 07:28 -0800]:

quoted

Introduce probes for supported BPF program types in libbpf, and call it
from bpftool to test what types are available on the system. The probe
simply consists in loading a very basic program of that type and see if
the verifier complains or not.

Sample output:

     # bpftool feature probe kernel
     ...
     Scanning eBPF program types...
     eBPF program_type socket_filter is available
     eBPF program_type kprobe is available
     eBPF program_type sched_cls is available
     ...

     # bpftool --json --pretty feature probe kernel
     {
         ...
         "program_types": {
             "have_socket_filter_prog_type": true,
             "have_kprobe_prog_type": true,
             "have_sched_cls_prog_type": true,
             ...
         }
     }

Hi Quentin,

Awesome work! I wondef if you have plan to add similar functionality for
attach types?

For example BPF_CGROUP_INET{4,6}_CONNECT were added in 4.17 but
BPF_CGROUP_UDP{4,6}_SENDMSG later in 4.18 even though they correspond to
same prog type (BPF_PROG_TYPE_CGROUP_SOCK_ADDR).

Hi Andrey, thanks! And yeah adding probes for the attach types would be 
one of the next logical steps, although to be honest it is not at the 
top of my to-do list right now. I'll probably add them eventually, but 
if you have a need for such probes today feel free to give it a go!

Best regards,
Quentin