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bpf: Use function pointers count as struct_ops links count

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[ Upstream commit 821a3fa32bbe3bc0fa23b3189325d3720a49a24c ]

Only function pointers in a struct_ops structure can be linked to bpf
progs, so set the links count to the function pointers count, instead
of the total members count in the structure.

Suggested-by: Martin KaFai Lau <martin.lau@linux.dev>
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20241112145849.3436772-3-xukuohai@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: 7c8ce4ffb684 ("bpf: Add kernel symbol for struct_ops trampoline")
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Xu Kuohai
2024-11-12 22:58:48 +08:00
committed by Greg Kroah-Hartman
parent 6271eab494
commit 9c44c06123
1 changed files with 25 additions and 10 deletions
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kernel/bpf/bpf_struct_ops.c
+25 -10
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@@ -32,7 +32,7 @@ struct bpf_struct_ops_map {
* (in kvalue.data). * (in kvalue.data).
*/ */
struct bpf_link **links; struct bpf_link **links;
u32 links_cnt; u32 funcs_cnt;
u32 image_pages_cnt; u32 image_pages_cnt;
/* image_pages is an array of pages that has all the trampolines /* image_pages is an array of pages that has all the trampolines
* that stores the func args before calling the bpf_prog. * that stores the func args before calling the bpf_prog.
@@ -481,11 +481,11 @@ static void bpf_struct_ops_map_put_progs(struct bpf_struct_ops_map *st_map)
{ {
u32 i; u32 i;
for (i = 0; i < st_map->links_cnt; i++) { for (i = 0; i < st_map->funcs_cnt; i++) {
if (st_map->links[i]) { if (!st_map->links[i])
bpf_link_put(st_map->links[i]); break;
st_map->links[i] = NULL; bpf_link_put(st_map->links[i]);
} st_map->links[i] = NULL;
} }
} }
@@ -601,6 +601,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
int prog_fd, err; int prog_fd, err;
u32 i, trampoline_start, image_off = 0; u32 i, trampoline_start, image_off = 0;
void *cur_image = NULL, *image = NULL; void *cur_image = NULL, *image = NULL;
struct bpf_link **plink;
if (flags) if (flags)
return -EINVAL; return -EINVAL;
@@ -639,6 +640,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
udata = &uvalue->data; udata = &uvalue->data;
kdata = &kvalue->data; kdata = &kvalue->data;
plink = st_map->links;
module_type = btf_type_by_id(btf_vmlinux, st_ops_ids[IDX_MODULE_ID]); module_type = btf_type_by_id(btf_vmlinux, st_ops_ids[IDX_MODULE_ID]);
for_each_member(i, t, member) { for_each_member(i, t, member) {
const struct btf_type *mtype, *ptype; const struct btf_type *mtype, *ptype;
@@ -714,7 +716,7 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
} }
bpf_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS, bpf_link_init(&link->link, BPF_LINK_TYPE_STRUCT_OPS,
&bpf_struct_ops_link_lops, prog); &bpf_struct_ops_link_lops, prog);
st_map->links[i] = &link->link; *plink++ = &link->link;
trampoline_start = image_off; trampoline_start = image_off;
err = bpf_struct_ops_prepare_trampoline(tlinks, link, err = bpf_struct_ops_prepare_trampoline(tlinks, link,
@@ -895,6 +897,19 @@ static int bpf_struct_ops_map_alloc_check(union bpf_attr *attr)
return 0; return 0;
} }
static u32 count_func_ptrs(const struct btf *btf, const struct btf_type *t)
{
int i;
u32 count;
const struct btf_member *member;
count = 0;
for_each_member(i, t, member)
if (btf_type_resolve_func_ptr(btf, member->type, NULL))
count++;
return count;
}
static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr) static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
{ {
const struct bpf_struct_ops_desc *st_ops_desc; const struct bpf_struct_ops_desc *st_ops_desc;
@@ -961,9 +976,9 @@ static struct bpf_map *bpf_struct_ops_map_alloc(union bpf_attr *attr)
map = &st_map->map; map = &st_map->map;
st_map->uvalue = bpf_map_area_alloc(vt->size, NUMA_NO_NODE); st_map->uvalue = bpf_map_area_alloc(vt->size, NUMA_NO_NODE);
st_map->links_cnt = btf_type_vlen(t); st_map->funcs_cnt = count_func_ptrs(btf, t);
st_map->links = st_map->links =
bpf_map_area_alloc(st_map->links_cnt * sizeof(struct bpf_links *), bpf_map_area_alloc(st_map->funcs_cnt * sizeof(struct bpf_link *),
NUMA_NO_NODE); NUMA_NO_NODE);
if (!st_map->uvalue || !st_map->links) { if (!st_map->uvalue || !st_map->links) {
ret = -ENOMEM; ret = -ENOMEM;
@@ -994,7 +1009,7 @@ static u64 bpf_struct_ops_map_mem_usage(const struct bpf_map *map)
usage = sizeof(*st_map) + usage = sizeof(*st_map) +
vt->size - sizeof(struct bpf_struct_ops_value); vt->size - sizeof(struct bpf_struct_ops_value);
usage += vt->size; usage += vt->size;
usage += btf_type_vlen(vt) * sizeof(struct bpf_links *); usage += st_map->funcs_cnt * sizeof(struct bpf_link *);
usage += PAGE_SIZE; usage += PAGE_SIZE;
return usage; return usage;
} }