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

Unified · Split

3 files

kernel/bpf/arraymap.c +8 −1
kernel/bpf/map_in_map.c +1 −2
net/xdp/xskmap.c +8 −1

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,

kernel/bpf/map_in_map.c+1−2

@@ -75,8 +75,7 @@ bool bpf_map_meta_equal(const struct bpf_map *meta0, · 74 unmodified lines
75	75	return meta0->map_type == meta1->map_type &&
76	76	meta0->key_size == meta1->key_size &&
77	77	meta0->value_size == meta1->value_size &&
78		− meta0->map_flags == meta1->map_flags &&
79		− meta0->max_entries == meta1->max_entries;
	78	+ meta0->map_flags == meta1->map_flags;
80	79	}
81	80
82	81	void bpf_map_fd_get_ptr(struct bpf_map map,

net/xdp/xskmap.c+8−1

@@ -254,9 +254,16 @@ void xsk_map_try_sock_delete(struct xsk_map map, struct xdp_sock xs, · 253 unmodified lines
254	254	spin_unlock_bh(&map->lock);
255	255	}
256	256
	257	+static bool xsk_map_meta_equal(const struct bpf_map *meta0,
	258	+ const struct bpf_map *meta1)
	259	+{
	260	+ return meta0->max_entries == meta1->max_entries &&
	261	+ bpf_map_meta_equal(meta0, meta1);
	262	+}
	263	+
257	264	static int xsk_map_btf_id;
258	265	const struct bpf_map_ops xsk_map_ops = {
259		− .map_meta_equal = bpf_map_meta_equal,
	266	+ .map_meta_equal = xsk_map_meta_equal,
260	267	.map_alloc = xsk_map_alloc,
261	268	.map_free = xsk_map_free,
262	269	.map_get_next_key = xsk_map_get_next_key,