[PATCH 5.15 047/244] bpf: Acquire map uref in .init_seq_private for sock{map,hash} iterator

Greg Kroah-Hartman
2022-08-23T09:47:49Z

From: Hou Tao <houtao1@huawei.com>

commit f0d2b2716d71778d0b0c8eaa433c073287d69d93 upstream.

sock_map_iter_attach_target() 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 sock_map_iter_detach_target() as part of
bpf_link_release(), or could be released in bpf_map_put_with_uref() as
part of bpf_map_release().

Fixing it by acquiring an extra map uref in .init_seq_private and
releasing it in .fini_seq_private.

Fixes: 0365351524d7 ("net: Allow iterating sockmap and sockhash")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220810080538.1845898-5-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/sock_map.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)

--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -789,13 +789,22 @@ static int sock_map_init_seq_private(voi
{
struct sock_map_seq_info *info = priv_data;

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

+static void sock_map_fini_seq_private(void *priv_data)
+{
+ struct sock_map_seq_info *info = priv_data;
+
+ bpf_map_put_with_uref(info->map);
+}
+
static const struct bpf_iter_seq_info sock_map_iter_seq_info = {
.seq_ops = &sock_map_seq_ops,
.init_seq_private = sock_map_init_seq_private,
+ .fini_seq_private = sock_map_fini_seq_private,
.seq_priv_size = sizeof(struct sock_map_seq_info),
};

@@ -1376,18 +1385,27 @@ static const struct seq_operations sock_
};

static int sock_hash_init_seq_private(void *priv_data,
- struct bpf_iter_aux_info *aux)
+ struct bpf_iter_aux_info *aux)
{
struct sock_hash_seq_info *info = priv_data;

+ bpf_map_inc_with_uref(aux->map);
info->map = aux->map;
info->htab = container_of(aux->map, struct bpf_shtab, map);
return 0;
}

+static void sock_hash_fini_seq_private(void *priv_data)
+{
+ struct sock_hash_seq_info *info = priv_data;
+
+ bpf_map_put_with_uref(info->map);
+}
+
static const struct bpf_iter_seq_info sock_hash_iter_seq_info = {
.seq_ops = &sock_hash_seq_ops,
.init_seq_private = sock_hash_init_seq_private,
+ .fini_seq_private = sock_hash_fini_seq_private,
.seq_priv_size = sizeof(struct sock_hash_seq_info),
};