1 files changed, 88 insertions, 0 deletions

diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 278490683d28..c43346cb3d76 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -533,6 +533,17 @@ static void bpf_struct_ops_map_put_progs(struct bpf_struct_ops_map *st_map)
 	}
 }
 
+static void bpf_struct_ops_map_dissoc_progs(struct bpf_struct_ops_map *st_map)
+{
+	u32 i;
+
+	for (i = 0; i < st_map->funcs_cnt; i++) {
+		if (!st_map->links[i])
+			break;
+		bpf_prog_disassoc_struct_ops(st_map->links[i]->prog);
+	}
+}
+
 static void bpf_struct_ops_map_free_image(struct bpf_struct_ops_map *st_map)
 {
 	int i;
@@ -801,6 +812,9 @@ static long bpf_struct_ops_map_update_elem(struct bpf_map *map, void *key,
 			goto reset_unlock;
 		}
 
+		/* Poison pointer on error instead of return for backward compatibility */
+		bpf_prog_assoc_struct_ops(prog, &st_map->map);
+
 		link = kzalloc(sizeof(*link), GFP_USER);
 		if (!link) {
 			bpf_prog_put(prog);
@@ -980,6 +994,8 @@ static void bpf_struct_ops_map_free(struct bpf_map *map)
 	if (btf_is_module(st_map->btf))
 		module_put(st_map->st_ops_desc->st_ops->owner);
 
+	bpf_struct_ops_map_dissoc_progs(st_map);
+
 	bpf_struct_ops_map_del_ksyms(st_map);
 
 	/* The struct_ops's function may switch to another struct_ops.
@@ -1396,6 +1412,78 @@ err_out:
 	return err;
 }
 
+int bpf_prog_assoc_struct_ops(struct bpf_prog *prog, struct bpf_map *map)
+{
+	struct bpf_map *st_ops_assoc;
+
+	guard(mutex)(&prog->aux->st_ops_assoc_mutex);
+
+	st_ops_assoc = rcu_dereference_protected(prog->aux->st_ops_assoc,
+						 lockdep_is_held(&prog->aux->st_ops_assoc_mutex));
+	if (st_ops_assoc && st_ops_assoc == map)
+		return 0;
+
+	if (st_ops_assoc) {
+		if (prog->type != BPF_PROG_TYPE_STRUCT_OPS)
+			return -EBUSY;
+
+		rcu_assign_pointer(prog->aux->st_ops_assoc, BPF_PTR_POISON);
+	} else {
+		/*
+		 * struct_ops map does not track associated non-struct_ops programs.
+		 * Bump the refcount to make sure st_ops_assoc is always valid.
+		 */
+		if (prog->type != BPF_PROG_TYPE_STRUCT_OPS)
+			bpf_map_inc(map);
+
+		rcu_assign_pointer(prog->aux->st_ops_assoc, map);
+	}
+
+	return 0;
+}
+
+void bpf_prog_disassoc_struct_ops(struct bpf_prog *prog)
+{
+	struct bpf_map *st_ops_assoc;
+
+	guard(mutex)(&prog->aux->st_ops_assoc_mutex);
+
+	st_ops_assoc = rcu_dereference_protected(prog->aux->st_ops_assoc,
+						 lockdep_is_held(&prog->aux->st_ops_assoc_mutex));
+	if (!st_ops_assoc || st_ops_assoc == BPF_PTR_POISON)
+		return;
+
+	if (prog->type != BPF_PROG_TYPE_STRUCT_OPS)
+		bpf_map_put(st_ops_assoc);
+
+	RCU_INIT_POINTER(prog->aux->st_ops_assoc, NULL);
+}
+
+/*
+ * Get a reference to the struct_ops struct (i.e., kdata) associated with a
+ * program. Should only be called in BPF program context (e.g., in a kfunc).
+ *
+ * If the returned pointer is not NULL, it must points to a valid struct_ops.
+ * The struct_ops map is not guaranteed to be initialized nor attached.
+ * Kernel struct_ops implementers are responsible for tracking and checking
+ * the state of the struct_ops if the use case requires an initialized or
+ * attached struct_ops.
+ */
+void *bpf_prog_get_assoc_struct_ops(const struct bpf_prog_aux *aux)
+{
+	struct bpf_struct_ops_map *st_map;
+	struct bpf_map *st_ops_assoc;
+
+	st_ops_assoc = rcu_dereference_check(aux->st_ops_assoc, bpf_rcu_lock_held());
+	if (!st_ops_assoc || st_ops_assoc == BPF_PTR_POISON)
+		return NULL;
+
+	st_map = (struct bpf_struct_ops_map *)st_ops_assoc;
+
+	return &st_map->kvalue.data;
+}
+EXPORT_SYMBOL_GPL(bpf_prog_get_assoc_struct_ops);
+
 void bpf_map_struct_ops_info_fill(struct bpf_map_info *info, struct bpf_map *map)
 {
 	struct bpf_struct_ops_map *st_map = (struct bpf_struct_ops_map *)map;