On Thu, May 4, 2023 at 1:05 PM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> On Tue, May 02, 2023 at 04:06:13PM -0700, Andrii Nakryiko wrote:
> > }
> >
> > -static struct bpf_map *array_map_alloc(union bpf_attr *attr)
> > +static u32 array_index_mask(u32 max_entries)
> > {
> > - bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
> > - int numa_node = bpf_map_attr_numa_node(attr);
> > - u32 elem_size, index_mask, max_entries;
> > - bool bypass_spec_v1 = bpf_bypass_spec_v1();
>
> static inline bool bpf_bypass_spec_v1(void)
> {
> return perfmon_capable();
> }
>
> > + /* unprivileged is OK, but we still record if we had CAP_BPF */
> > + unpriv = !bpf_capable();
>
> map->unpriv flag makes sense as !CAP_BPF,
> but it's not equivalent to bpf_bypass_spec_v1.
>
argh, right, it's perfmon_capable() :(
what do you propose? do bpf_capable and perfmon_capable fields for
each map separately? or keep unpriv and add perfmon_capable
separately? or any better ideas?..
> > break;
> > default:
> > WARN(1, "unsupported map type %d", map_type);
> > return -EPERM;
> > }
> >
> > + /* ARRAY-like maps have special sizing provisions for mitigating Spectre v1 */
> > + if (unpriv) {
> > + switch (map_type) {
> > + case BPF_MAP_TYPE_ARRAY:
> > + case BPF_MAP_TYPE_PERCPU_ARRAY:
> > + case BPF_MAP_TYPE_PROG_ARRAY:
> > + case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
> > + case BPF_MAP_TYPE_CGROUP_ARRAY:
> > + case BPF_MAP_TYPE_ARRAY_OF_MAPS:
> > + err = bpf_array_adjust_for_spec_v1(attr);
> > + if (err)
> > + return err;
> > + break;
> > + }
> > + }
> > +
> > map = ops->map_alloc(attr);
> > if (IS_ERR(map))
> > return PTR_ERR(map);
> > map->ops = ops;
> > map->map_type = map_type;
> > + map->unpriv = unpriv;
> >
> > err = bpf_obj_name_cpy(map->name, attr->map_name,
> > sizeof(attr->map_name));
> > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> > index ff4a8ab99f08..481aaf189183 100644
> > --- a/kernel/bpf/verifier.c
> > +++ b/kernel/bpf/verifier.c
> > @@ -8731,11 +8731,9 @@ record_func_map(struct bpf_verifier_env *env, struct bpf_call_arg_meta *meta,
> > }
> >
> > if (!BPF_MAP_PTR(aux->map_ptr_state))
> > - bpf_map_ptr_store(aux, meta->map_ptr,
> > - !meta->map_ptr->bypass_spec_v1);
> > + bpf_map_ptr_store(aux, meta->map_ptr, meta->map_ptr->unpriv);
> > else if (BPF_MAP_PTR(aux->map_ptr_state) != meta->map_ptr)
> > - bpf_map_ptr_store(aux, BPF_MAP_PTR_POISON,
> > - !meta->map_ptr->bypass_spec_v1);
> > + bpf_map_ptr_store(aux, BPF_MAP_PTR_POISON, meta->map_ptr->unpriv);
> > return 0;
> > }
> >
> > --
> > 2.34.1
> >
