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@kernel.org
---
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; } }