We need to extend the bpf_timer API, but the way forward relies on kfuncs.
So make bpf_timer known for kfuncs from the verifier PoV
Signed-off-by: Benjamin Tissoires <bentiss@xxxxxxxxxx>
---
changes in v5:
- also check for the reg offset
changes in v4:
- enforce KF_ARG_PTR_TO_TIMER to be of type PTR_TO_MAP_VALUE
new in v3 (split from v2 02/10)
---
kernel/bpf/verifier.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 63749ad5ac6b..24a604e26ec7 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -10826,6 +10826,7 @@ enum {
KF_ARG_LIST_NODE_ID,
KF_ARG_RB_ROOT_ID,
KF_ARG_RB_NODE_ID,
+ KF_ARG_TIMER_ID,
};
BTF_ID_LIST(kf_arg_btf_ids)
@@ -10834,6 +10835,7 @@ BTF_ID(struct, bpf_list_head)
BTF_ID(struct, bpf_list_node)
BTF_ID(struct, bpf_rb_root)
BTF_ID(struct, bpf_rb_node)
+BTF_ID(struct, bpf_timer_kern)
static bool __is_kfunc_ptr_arg_type(const struct btf *btf,
const struct btf_param *arg, int type)
@@ -10877,6 +10879,12 @@ static bool is_kfunc_arg_rbtree_node(const struct btf *btf, const struct btf_par
return __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_RB_NODE_ID);
}
+static bool is_kfunc_arg_timer(const struct btf *btf, const struct btf_param *arg)
+{
+ bool ret = __is_kfunc_ptr_arg_type(btf, arg, KF_ARG_TIMER_ID);
+ return ret;
+}
+
static bool is_kfunc_arg_callback(struct bpf_verifier_env *env, const struct btf *btf,
const struct btf_param *arg)
{
@@ -10946,6 +10954,7 @@ enum kfunc_ptr_arg_type {
KF_ARG_PTR_TO_NULL,
KF_ARG_PTR_TO_CONST_STR,
KF_ARG_PTR_TO_MAP,
+ KF_ARG_PTR_TO_TIMER,
};
enum special_kfunc_type {
@@ -11102,6 +11111,9 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env,
if (is_kfunc_arg_map(meta->btf, &args[argno]))
return KF_ARG_PTR_TO_MAP;
+ if (is_kfunc_arg_timer(meta->btf, &args[argno]))
+ return KF_ARG_PTR_TO_TIMER;
+
if ((base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)])) {
if (!btf_type_is_struct(ref_t)) {
verbose(env, "kernel function %s args#%d pointer type %s %s is not supported\n",
@@ -11735,6 +11747,7 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
case KF_ARG_PTR_TO_CALLBACK:
case KF_ARG_PTR_TO_REFCOUNTED_KPTR:
case KF_ARG_PTR_TO_CONST_STR:
+ case KF_ARG_PTR_TO_TIMER:
/* Trusted by default */
break;
default:
@@ -12021,6 +12034,16 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
if (ret)
return ret;
break;
+ case KF_ARG_PTR_TO_TIMER:
+ if (reg->type != PTR_TO_MAP_VALUE) {
+ verbose(env, "arg#%d doesn't point to a map value\n", i);
+ return -EINVAL;
+ }
+ if (reg->off) {
+ verbose(env, "arg#%d offset can not be greater than 0\n", i);
+ return -EINVAL;
+ }
+ break;
}
}
--
2.44.0
