Re: [PATCH bpf-next v2 1/2] bpf: Add struct bpf_token_info

[Tao Chen]

在 2025/7/16 05:52, Andrii Nakryiko 写道:
> On Mon, Jul 14, 2025 at 8:59 PM Tao Chen <chen.dylane@xxxxxxxxx> wrote:
> > The 'commit 35f96de04127 ("bpf: Introduce BPF token object")' added
> > BPF token as a new kind of BPF kernel object. And BPF_OBJ_GET_INFO_BY_FD
> > already used to get BPF object info, so we can also get token info with
> > this cmd.
> > One usage scenario, when program runs failed with token, because of
> > the permission failure, we can report what BPF token is allowing with
> > this API for debugging.
> >
> > Signed-off-by: Tao Chen <chen.dylane@xxxxxxxxx>
> > ---
> >   include/linux/bpf.h            | 11 +++++++++++
> >   include/uapi/linux/bpf.h       |  8 ++++++++
> >   kernel/bpf/syscall.c           | 18 ++++++++++++++++++
> >   kernel/bpf/token.c             | 28 +++++++++++++++++++++++++++-
> >   tools/include/uapi/linux/bpf.h |  8 ++++++++
> >   5 files changed, 72 insertions(+), 1 deletion(-)
>
> LGTM, but see a nit below and in selftest patch
>
> Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
>
> [...]
>
> > +int bpf_token_get_info_by_fd(struct bpf_token *token,
> > +                            const union bpf_attr *attr,
> > +                            union bpf_attr __user *uattr)
> > +{
> > +       struct bpf_token_info __user *uinfo;
> > +       struct bpf_token_info info;
> > +       u32 info_copy, uinfo_len;
> > +
> > +       uinfo = u64_to_user_ptr(attr->info.info);
> > +       uinfo_len = attr->info.info_len;
> > +
> > +       info_copy = min_t(u32, uinfo_len, sizeof(info));
>
> you don't use info_len past this point, so just reassign it instead of
> adding another variable (info_copy); seems like some other
> get_info_by_fd functions use the same approach

will change it in v3, thanks.

> > +       memset(&info, 0, sizeof(info));
> > +
> > +       info.allowed_cmds = token->allowed_cmds;
> > +       info.allowed_maps = token->allowed_maps;
> > +       info.allowed_progs = token->allowed_progs;
> > +       info.allowed_attachs = token->allowed_attachs;
> > +
> > +       if (copy_to_user(uinfo, &info, info_copy) ||
> > +           put_user(info_copy, &uattr->info.info_len))
> > +               return -EFAULT;
> > +
> > +       return 0;
> > +}
> > +
>
> [...]


--
Best Regards
Tao Chen