Re: [PATCH bpf-next v1 1/9] bpf: Add mkdir, rmdir, unlink syscalls for prog_bpf_syscall

[Hao Luo]

On Thu, Mar 3, 2022 at 11:13 AM Yonghong Song <yhs@xxxxxx> wrote:
>
>
>
> On 3/3/22 10:56 AM, Hao Luo wrote:
> > On Wed, Mar 2, 2022 at 12:55 PM Yonghong Song <yhs@xxxxxx> wrote:
> >> On 2/25/22 3:43 PM, Hao Luo wrote:
> >>> @@ -5086,6 +5086,29 @@ union bpf_attr {
> >>>     *  Return
> >>>     *          0 on success, or a negative error in case of failure. On error
> >>>     *          *dst* buffer is zeroed out.
> >>> + *
> >>> + * long bpf_mkdir(const char *pathname, int pathname_sz, u32 mode)
> >>
> >> Can we make pathname_sz to be u32 instead of int? pathname_sz should
> >> never be negative any way.
> >>
> >> Also, I think it is a good idea to add 'u64 flags' parameter for all
> >> three helpers, so we have room in the future to tune for new use cases.
> >>
> >
> > SG. Will make this change.
> >
> > Actually, I think I need to cap patthname_sz from above, to ensure
> > pathname_sz isn't too big. Is that necessary? I see there are other
> > helpers that don't have this type of check.
>
> There is no need. The verifier should ensure the memory held by pathname
> will have at least size of pathname_sz.
>

SG. Thanks!