On Tue, Apr 11, 2023 at 09:32:54PM -0700, Andrii Nakryiko wrote:
> Keep all the relevant generic sanity checks, permission checks, and
> creation and initialization logic in one linear piece of code. Currently
> helper function that handles memory allocation and partial
> initialization is split apart and is about 1000 lines higher in the
> file, hurting readability.
At first glance, this seems like a step in the wrong direction: having a
single-purpose function pulled out of a larger one seems like a good
thing for stuff like unit testing, etc. Unless there's a reason later in
the series for this inlining (which should be called out in the
changelog here), I would say if it is only readability, just move the
function down 1000 lines but leave it a separate function.
-Kees
>
> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> ---
> kernel/bpf/syscall.c | 54 ++++++++++++++++++--------------------------
> 1 file changed, 22 insertions(+), 32 deletions(-)
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index c1d268025985..a090737f98ea 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -108,37 +108,6 @@ const struct bpf_map_ops bpf_map_offload_ops = {
> .map_mem_usage = bpf_map_offload_map_mem_usage,
> };
>
> -static struct bpf_map *find_and_alloc_map(union bpf_attr *attr)
> -{
> - const struct bpf_map_ops *ops;
> - u32 type = attr->map_type;
> - struct bpf_map *map;
> - int err;
> -
> - if (type >= ARRAY_SIZE(bpf_map_types))
> - return ERR_PTR(-EINVAL);
> - type = array_index_nospec(type, ARRAY_SIZE(bpf_map_types));
> - ops = bpf_map_types[type];
> - if (!ops)
> - return ERR_PTR(-EINVAL);
> -
> - if (ops->map_alloc_check) {
> - err = ops->map_alloc_check(attr);
> - if (err)
> - return ERR_PTR(err);
> - }
> - if (attr->map_ifindex)
> - ops = &bpf_map_offload_ops;
> - if (!ops->map_mem_usage)
> - return ERR_PTR(-EINVAL);
> - map = ops->map_alloc(attr);
> - if (IS_ERR(map))
> - return map;
> - map->ops = ops;
> - map->map_type = type;
> - return map;
> -}
> -
> static void bpf_map_write_active_inc(struct bpf_map *map)
> {
> atomic64_inc(&map->writecnt);
> @@ -1124,7 +1093,9 @@ static int map_check_btf(struct bpf_map *map, const struct btf *btf,
> /* called via syscall */
> static int map_create(union bpf_attr *attr)
> {
> + const struct bpf_map_ops *ops;
> int numa_node = bpf_map_attr_numa_node(attr);
> + u32 map_type = attr->map_type;
> struct btf_field_offs *foffs;
> struct bpf_map *map;
> int f_flags;
> @@ -1167,9 +1138,28 @@ static int map_create(union bpf_attr *attr)
> return -EINVAL;
>
> /* find map type and init map: hashtable vs rbtree vs bloom vs ... */
> - map = find_and_alloc_map(attr);
> + map_type = attr->map_type;
> + if (map_type >= ARRAY_SIZE(bpf_map_types))
> + return -EINVAL;
> + map_type = array_index_nospec(map_type, ARRAY_SIZE(bpf_map_types));
> + ops = bpf_map_types[map_type];
> + if (!ops)
> + return -EINVAL;
> +
> + if (ops->map_alloc_check) {
> + err = ops->map_alloc_check(attr);
> + if (err)
> + return err;
> + }
> + if (attr->map_ifindex)
> + ops = &bpf_map_offload_ops;
> + if (!ops->map_mem_usage)
> + return -EINVAL;
> + map = ops->map_alloc(attr);
> if (IS_ERR(map))
> return PTR_ERR(map);
> + map->ops = ops;
> + map->map_type = map_type;
>
> err = bpf_obj_name_cpy(map->name, attr->map_name,
> sizeof(attr->map_name));
> --
> 2.34.1
>
--
Kees Cook
