[bpf-next,v3,12/16] bpf: Disable unsupported operations for map with dynptr key

Commit Message

Hou Tao March 27, 2025, 8:34 a.m. UTC

From: Hou Tao <[e-mail]>

Batched map operations, dumping the map content through bpffs, and
iterating over each element using the bpf_for_each_map_elem() helper or
the bpf map element iterator are not supported for maps with dynptr
keys. Therefore, disable these operations for now.

Signed-off-by: Hou Tao <[e-mail]>
---
 include/linux/bpf.h   | 3 ++-
 kernel/bpf/map_iter.c | 3 +++
 kernel/bpf/syscall.c  | 4 ++++
 kernel/bpf/verifier.c | 4 ++++
 4 files changed, 13 insertions(+), 1 deletion(-)

Patch

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 4f4b43b68f8d1..59295dd8d6fd3 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -629,7 +629,8 @@  static inline bool bpf_map_offload_neutral(const struct bpf_map *map)
 static inline bool bpf_map_support_seq_show(const struct bpf_map *map)
 {
 	return (map->btf_value_type_id || map->btf_vmlinux_value_type_id) &&
-		map->ops->map_seq_show_elem;
+		map->ops->map_seq_show_elem &&
+		!bpf_map_has_dynptr_key(map);
 }
 
 int map_check_no_btf(const struct bpf_map *map,
diff --git a/kernel/bpf/map_iter.c b/kernel/bpf/map_iter.c
index 9575314f40a69..775d8bc63ed5d 100644
--- a/kernel/bpf/map_iter.c
+++ b/kernel/bpf/map_iter.c
@@ -113,6 +113,9 @@  static int bpf_iter_attach_map(struct bpf_prog *prog,
 	if (IS_ERR(map))
 		return PTR_ERR(map);
 
+	if (bpf_map_has_dynptr_key(map))
+		goto put_map;
+
 	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
 	    map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||
 	    map->map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 40c3d85b06bae..24599749dc6f9 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -5508,6 +5508,10 @@  static int bpf_map_do_batch(const union bpf_attr *attr,
 		err = -EPERM;
 		goto err_put;
 	}
+	if (bpf_map_has_dynptr_key(map)) {
+		err = -EOPNOTSUPP;
+		goto err_put;
+	}
 
 	if (cmd == BPF_MAP_LOOKUP_BATCH)
 		BPF_DO_BATCH(map->ops->map_lookup_batch, map, attr, uattr);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 05a5636ae4984..fea94fcd8bf25 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -10246,6 +10246,10 @@  static int check_map_func_compatibility(struct bpf_verifier_env *env,
 		if (map->map_type != BPF_MAP_TYPE_CGRP_STORAGE)
 			goto error;
 		break;
+	case BPF_FUNC_for_each_map_elem:
+		if (bpf_map_has_dynptr_key(map))
+			goto error;
+		break;
 	default:
 		break;
 	}