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

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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.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200828011813.1970516-1-kafai@fb.com
This commit is contained in:
Martin KaFai Lau
2020-08-27 18:18:13 -07:00
committed by Daniel Borkmann
parent f4d0525921
commit 134fede4ee
3 changed files with 17 additions and 4 deletions
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9
kernel/bpf/arraymap.c
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@@ -487,6 +487,13 @@ static int array_map_mmap(struct bpf_map *map, struct vm_area_struct *vma)
vma->vm_pgoff + pgoff);
}
static bool array_map_meta_equal(const struct bpf_map *meta0,
const struct bpf_map *meta1)
{
return meta0->max_entries == meta1->max_entries &&
bpf_map_meta_equal(meta0, meta1);
}
struct bpf_iter_seq_array_map_info {
struct bpf_map *map;
void *percpu_value_buf;
@@ -625,7 +632,7 @@ static const struct bpf_iter_seq_info iter_seq_info = {
static int array_map_btf_id;
const struct bpf_map_ops array_map_ops = {
.map_meta_equal = bpf_map_meta_equal,
.map_meta_equal = array_map_meta_equal,
.map_alloc_check = array_map_alloc_check,
.map_alloc = array_map_alloc,
.map_free = array_map_free,