bpf: Emit global subprog name in verifier logs

We have the name, instead of emitting just func#N to identify global
subprog, augment verifier log messages with actual function name to make
it more user-friendly.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231124035937.403208-2-andrii@kernel.org

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 405da1f9e724d9ef52694e6ae48d2ba8c02a932b..a2939ebf26385e34fc9398b0360451c2303af72b 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -339,6 +339,11 @@ struct bpf_kfunc_call_arg_meta {
 
 struct btf *btf_vmlinux;
 
+static const char *btf_type_name(const struct btf *btf, u32 id)
+{
+       return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off);
+}
+
 static DEFINE_MUTEX(bpf_verifier_lock);
 static DEFINE_MUTEX(bpf_percpu_ma_lock);
 
@@ -418,6 +423,17 @@ static bool subprog_is_global(const struct bpf_verifier_env *env, int subprog)
        return aux && aux[subprog].linkage == BTF_FUNC_GLOBAL;
 }
 
+static const char *subprog_name(const struct bpf_verifier_env *env, int subprog)
+{
+       struct bpf_func_info *info;
+
+       if (!env->prog->aux->func_info)
+               return "";
+
+       info = &env->prog->aux->func_info[subprog];
+       return btf_type_name(env->prog->aux->btf, info->type_id);
+}
+
 static bool reg_may_point_to_spin_lock(const struct bpf_reg_state *reg)
 {
        return btf_record_has_field(reg_btf_record(reg), BPF_SPIN_LOCK);
@@ -587,11 +603,6 @@ static int iter_get_spi(struct bpf_verifier_env *env, struct bpf_reg_state *reg,
        return stack_slot_obj_get_spi(env, reg, "iter", nr_slots);
 }
 
-static const char *btf_type_name(const struct btf *btf, u32 id)
-{
-       return btf_name_by_offset(btf, btf_type_by_id(btf, id)->name_off);
-}
-
 static enum bpf_dynptr_type arg_to_dynptr_type(enum bpf_arg_type arg_type)
 {
        switch (arg_type & DYNPTR_TYPE_FLAG_MASK) {
@@ -9269,13 +9280,16 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
        if (err == -EFAULT)
                return err;
        if (subprog_is_global(env, subprog)) {
+               const char *sub_name = subprog_name(env, subprog);
+
                if (err) {
-                       verbose(env, "Caller passes invalid args into func#%d\n", subprog);
+                       verbose(env, "Caller passes invalid args into func#%d ('%s')\n",
+                               subprog, sub_name);
                        return err;
                }
 
-               if (env->log.level & BPF_LOG_LEVEL)
-                       verbose(env, "Func#%d is global and valid. Skipping.\n", subprog);
+               verbose(env, "Func#%d ('%s') is global and assumed valid.\n",
+                       subprog, sub_name);
                clear_caller_saved_regs(env, caller->regs);
 
                /* All global functions return a 64-bit SCALAR_VALUE */
@@ -19893,9 +19907,8 @@ static int do_check_subprogs(struct bpf_verifier_env *env)
                if (ret) {
                        return ret;
                } else if (env->log.level & BPF_LOG_LEVEL) {
-                       verbose(env,
-                               "Func#%d is safe for any args that match its prototype\n",
-                               i);
+                       verbose(env, "Func#%d ('%s') is safe for any args that match its prototype\n",
+                               i, subprog_name(env, i));
                }
        }
        return 0;