Re: [PATCH] bpf: Specify access type of bpf_sysctl_get_name args

[Jerome Marchand <jmarchan@redhat.com>]

On 28/05/2025 18:41, Eduard Zingerman wrote:
> Jerome Marchand <jmarchan@redhat.com> writes:
> 
> [...]
> 
>>> Looks like we don't run bpf_sysctl_get_name tests on the CI.
>>> CI executes the following binaries:
>>> - test_progs{,-no_alu32,-cpuv4}
>>> - test_verifier
>>> - test_maps
>>> test_progs is what is actively developed.
>>> I agree with the reasoning behind this patch, however, could you
>>> please
>>> add a selftest demonstrating unsafe behaviour?
>>
>> Do you mean to write a selftest that demonstrate the current unsafe
>> behavior of the bpf_sysctl_get_name helper? I could write something
>> similar as the failing test_sysctl cases.
> 
> Yes, something like that, taking an unsafe action based on content of
> the buffer after the helper call.

Alright, I'll do that.

> 
>> I'm thinking that a more general test that would check that helpers
>> don't access memory in a different way than advertised in their
>> prototype would be more useful. But that's quite a different endeavor.
> 
> That would be interesting, I think.
> Depends on how much time you need to write such a test.

I might think about it, but ATM, I just don't have time to do that. If 
someone is interested in implementing it, be my guest.

> 
> [...]
>