summaryrefslogtreecommitdiff
path: root/kernel/bpf/hashtab.c
diff options
context:
space:
mode:
authorMartin KaFai Lau <kafai@fb.com>2020-08-28 04:18:06 +0300
committerDaniel Borkmann <daniel@iogearbox.net>2020-08-28 16:41:30 +0300
commitf4d05259213ff1e91f767c91dcab455f68308fac (patch)
tree9d9bb0f7f1913ac00d3e4f743efb486c06ed9785 /kernel/bpf/hashtab.c
parentb0c9eb37817943840a1a82dbc998c491609a0afd (diff)
downloadlinux-f4d05259213ff1e91f767c91dcab455f68308fac.tar.xz
bpf: Add map_meta_equal map ops
Some properties of the inner map is used in the verification time. When an inner map is inserted to an outer map at runtime, bpf_map_meta_equal() is currently used to ensure those properties of the inserting inner map stays the same as the verification time. In particular, the current bpf_map_meta_equal() checks max_entries which turns out to be too restrictive for most of the maps which do not use max_entries during the verification time. It limits the use case that wants to replace a smaller inner map with a larger inner map. There are some maps do use max_entries during verification though. For example, the map_gen_lookup in array_map_ops uses the max_entries to generate the inline lookup code. To accommodate differences between maps, the map_meta_equal is added to bpf_map_ops. Each map-type can decide what to check when its map is used as an inner map during runtime. Also, some map types cannot be used as an inner map and they are currently black listed in bpf_map_meta_alloc() in map_in_map.c. It is not unusual that the new map types may not aware that such blacklist exists. This patch enforces an explicit opt-in and only allows a map to be used as an inner map if it has implemented the map_meta_equal ops. It is based on the discussion in [1]. All maps that support inner map has its map_meta_equal points to bpf_map_meta_equal in this patch. A later patch will relax the max_entries check for most maps. bpf_types.h counts 28 map types. This patch adds 23 ".map_meta_equal" by using coccinelle. -5 for BPF_MAP_TYPE_PROG_ARRAY BPF_MAP_TYPE_(PERCPU)_CGROUP_STORAGE BPF_MAP_TYPE_STRUCT_OPS BPF_MAP_TYPE_ARRAY_OF_MAPS BPF_MAP_TYPE_HASH_OF_MAPS The "if (inner_map->inner_map_meta)" check in bpf_map_meta_alloc() is moved such that the same error is returned. [1]: https://lore.kernel.org/bpf/20200522022342.899756-1-kafai@fb.com/ Signed-off-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200828011806.1970400-1-kafai@fb.com
Diffstat (limited to 'kernel/bpf/hashtab.c')
-rw-r--r--kernel/bpf/hashtab.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 78dfff6a501b..ad80f45774e7 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -1810,6 +1810,7 @@ static const struct bpf_iter_seq_info iter_seq_info = {
static int htab_map_btf_id;
const struct bpf_map_ops htab_map_ops = {
+ .map_meta_equal = bpf_map_meta_equal,
.map_alloc_check = htab_map_alloc_check,
.map_alloc = htab_map_alloc,
.map_free = htab_map_free,
@@ -1827,6 +1828,7 @@ const struct bpf_map_ops htab_map_ops = {
static int htab_lru_map_btf_id;
const struct bpf_map_ops htab_lru_map_ops = {
+ .map_meta_equal = bpf_map_meta_equal,
.map_alloc_check = htab_map_alloc_check,
.map_alloc = htab_map_alloc,
.map_free = htab_map_free,
@@ -1947,6 +1949,7 @@ static void htab_percpu_map_seq_show_elem(struct bpf_map *map, void *key,
static int htab_percpu_map_btf_id;
const struct bpf_map_ops htab_percpu_map_ops = {
+ .map_meta_equal = bpf_map_meta_equal,
.map_alloc_check = htab_map_alloc_check,
.map_alloc = htab_map_alloc,
.map_free = htab_map_free,
@@ -1963,6 +1966,7 @@ const struct bpf_map_ops htab_percpu_map_ops = {
static int htab_lru_percpu_map_btf_id;
const struct bpf_map_ops htab_lru_percpu_map_ops = {
+ .map_meta_equal = bpf_map_meta_equal,
.map_alloc_check = htab_map_alloc_check,
.map_alloc = htab_map_alloc,
.map_free = htab_map_free,