[LTP] question about the EPERM error of LTP bpf test

[Jan Stancek]

----- Original Message -----
> Hi All
> 
> Now, I test bpf_prog02 and bpf_prog03 in my system(4.18.0-107.el8.x86_64).
> 
> #./bpf_prog03
> tst_buffers.c:55: INFO: Test is using guarded buffers
> tst_test.c:1137: INFO: Timeout per run is 0h 05m 00s
> bpf_common.h:18: INFO: Raising RLIMIT_MEMLOCK to 262143
> tst_capability.c:29: INFO: Dropping CAP_SYS_ADMIN(21)
> bpf_common.h:37: CONF: bpf() requires CAP_SYS_ADMIN on this system: EPERM (1)
> #
> 
> Jan Stancek has added rlimit_bump_memlock function to avoid EPERM errno,
> but I still can meet this problem every time even though I have increased
> BPF_MEMLOCK_ADD limit.

This is likely not related to rlimit. Can you check if unprivileged bpf is allowed:
  cat /proc/sys/kernel/unprivileged_bpf_disabled

> 
> How can I run the two cases normally? Also, this error log(requires
> CAP_SYS_ADMIN on this system: EPERM
> ) makes me confused in this situation(because case drops CAP_SYS_ADMIN, but
> log reports need CAP_SYS_ADMIN)
> and I think we may change it into "require CAP_SYS_ADMIN or max locked memory
> limit is too low".
> 
> Or, can I keep CAP_SYS_ADMIN cap in bpf_prog02/[3]?
> 
> 
> Thanks
> Yang Xu
>   
> 
> 
> 
>