Merge branch 'fixes for bpf map iterator'

Hou Tao says:

====================

From: Hou Tao <houtao1@huawei.com>

Hi,

The patchset constitues three fixes for bpf map iterator:

(1) patch 1~4: fix user-after-free during reading map iterator fd
It is possible when both the corresponding link fd and map fd are
closed bfore reading the iterator fd. I had squashed these four patches
into one, but it was not friendly for stable backport, so I break these
fixes into four single patches in the end. Patch 7 is its testing patch.

(2) patch 5: fix invalidity check for values in sk local storage map
Patch 8 adds two tests for it.

(3) patch 6: reject sleepable program for non-resched map iterator
Patch 9 add a test for it.

Please check the individual patches for more details. And comments are
always welcome.

Regards,
Tao

Changes since v2:
* patch 1~6: update commit messages (from Yonghong & Martin)
* patch 7: add more detailed comments (from Yonghong)
* patch 8: use NULL directly instead of (void *)0

v1: https://lore.kernel.org/bpf/20220806074019.2756957-1-houtao@huaweicloud.com
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 29 insertions, 3 deletions

diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c
index a25ec93729b9..1b7f385643b4 100644
--- a/net/core/bpf_sk_storage.c
+++ b/net/core/bpf_sk_storage.c
@@ -875,10 +875,18 @@ static int bpf_iter_init_sk_storage_map(void *priv_data,
 {
 	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)
@@ -896,7 +904,7 @@ static int bpf_iter_attach_map(struct bpf_prog *prog,
 	if (map->map_type != BPF_MAP_TYPE_SK_STORAGE)
 		goto put_map;
 
-	if (prog->aux->max_rdonly_access > map->value_size) {
+	if (prog->aux->max_rdwr_access > map->value_size) {
 		err = -EACCES;
 		goto put_map;
 	}
@@ -924,7 +932,7 @@ static const struct seq_operations bpf_sk_storage_map_seq_ops = {
 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),
 };
 
diff --git a/net/core/sock_map.c b/net/core/sock_map.c
index 028813dfecb0..9a9fb9487d63 100644
--- a/net/core/sock_map.c
+++ b/net/core/sock_map.c
@@ -783,13 +783,22 @@ static int sock_map_init_seq_private(void *priv_data,
 {
 	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),
 };
 
@@ -1369,18 +1378,27 @@ static const struct seq_operations sock_hash_seq_ops = {
 };
 
 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),
 };