[PATCH 5.15 046/244] bpf: Acquire map uref in .init_seq_private for sock local storage map iterator

Greg Kroah-Hartman
2022-08-23T09:47:29Z

From: Hou Tao <houtao1@huawei.com>

commit 3c5f6e698b5c538bbb23cd453b22e1e4922cffd8 upstream.

bpf_iter_attach_map() acquires a map uref, and the uref may be released
before or in the middle of iterating map elements. For example, the uref
could be released in bpf_iter_detach_map() as part of
bpf_link_release(), or could be released in bpf_map_put_with_uref() as
part of bpf_map_release().

So acquiring an extra map uref in bpf_iter_init_sk_storage_map() and
releasing it in bpf_iter_fini_sk_storage_map().

Fixes: 5ce6e77c7edf ("bpf: Implement bpf iterator for sock local storage map")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220810080538.1845898-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/bpf_sk_storage.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

--- a/net/core/bpf_sk_storage.c
+++ b/net/core/bpf_sk_storage.c
@@ -865,10 +865,18 @@ static int bpf_iter_init_sk_storage_map(
{
struct bpf_iter_seq_sk_storage_map_info *seq_info = priv_data;

+ bpf_map_inc_with_uref(aux->map);
seq_info->map = aux->map;
return 0;
}

+static void bpf_iter_fini_sk_storage_map(void *priv_data)
+{
+ struct bpf_iter_seq_sk_storage_map_info *seq_info = priv_data;
+
+ bpf_map_put_with_uref(seq_info->map);
+}
+
static int bpf_iter_attach_map(struct bpf_prog *prog,
union bpf_iter_link_info *linfo,
struct bpf_iter_aux_info *aux)
@@ -914,7 +922,7 @@ static const struct seq_operations bpf_s
static const struct bpf_iter_seq_info iter_seq_info = {
.seq_ops = &bpf_sk_storage_map_seq_ops,
.init_seq_private = bpf_iter_init_sk_storage_map,
- .fini_seq_private = NULL,
+ .fini_seq_private = bpf_iter_fini_sk_storage_map,
.seq_priv_size = sizeof(struct bpf_iter_seq_sk_storage_map_info),
};