bpf: Relax max_entries check for most of the inner map types

Most of the maps do not use max_entries during verification time. Thus, those map_meta_equal() do not need to enforce max_entries when it is inserted as an inner map during runtime. The max_entries check is removed from the default implementation bpf_map_meta_equal(). The prog_array_map and xsk_map are exception. Its map_gen_lookup uses max_entries to generate inline lookup code. Thus, they will implement its own map_meta_equal() to enforce max_entries. Since there are only two cases now, the max_entries check is not refactored and stays in its own .c file.

Martin KaFai Lau committed 6 years ago

Commit 134fede1 parent f4d05253 files · +17 −4Browse files

Showing the changes to kernel/bpf/arraymap.c (1 of 3 files). Show all

Unified · Split

kernel/bpf/arraymap.c+8−1

@@ -487,6 +487,13 @@ static int array_map_mmap(struct bpf_map map, struct vm_area_struct vma) · 486 unmodified lines
487	487	vma->vm_pgoff + pgoff);
488	488	}
489	489
	490	+static bool array_map_meta_equal(const struct bpf_map *meta0,
	491	+ const struct bpf_map *meta1)
	492	+{
	493	+ return meta0->max_entries == meta1->max_entries &&
	494	+ bpf_map_meta_equal(meta0, meta1);
	495	+}
	496	+
490	497	struct bpf_iter_seq_array_map_info {
491	498	struct bpf_map *map;
492	499	void *percpu_value_buf;
@@ -625,7 +632,7 @@ static const struct bpf_iter_seq_info iter_seq_info = { · 132 unmodified lines
625	632
626	633	static int array_map_btf_id;
627	634	const struct bpf_map_ops array_map_ops = {
628		− .map_meta_equal = bpf_map_meta_equal,
	635	+ .map_meta_equal = array_map_meta_equal,
629	636	.map_alloc_check = array_map_alloc_check,
630	637	.map_alloc = array_map_alloc,
631	638	.map_free = array_map_free,