Re: How to get system localtime/wall time from eBPF?

[Jesper Dangaard Brouer <jbrouer@xxxxxxxxxx>]

On 20/03/2023 16.33, Vincent Li wrote:
> if I have a XDP based firewall to block ip  access based on system
> localtime/wall time, is it still impossible like what mentioned here
> https://github.com/xdp-project/xdp-tutorial/issues/204#issuecomment-819419800?
> If so, is there any way to workaround this?

You could use the BPF-helper named: bpf_ktime_get_tai_ns()

See man clock_gettime(2). It is the same as CLOCK_TAI, which is
(currently) offset with 37 sec to CLOCK_REALTIME which is wall-clock.

Perhaps kernel should be extended with a bpf_ktime_get_wall_ns() ?

--Jesper