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Mon, 28 Sep 2026 11:14:31 -0700 (PDT) Received: from localhost ([2a03:2880:ff:6::]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-81d583f8a58sm2365374a34.10.2026.09.28.11.14.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Sep 2026 11:14:29 -0700 (PDT) From: Amery Hung To: bpf@vger.kernel.org Cc: alexei.starovoitov@gmail.com, andrii@kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, memxor@gmail.com, ameryhung@gmail.com, kernel-team@meta.com Subject: [PATCH bpf-next v2 09/11] bpf: Check global subprog BTF-ID arguments in the common path Date: Mon, 28 Sep 2026 11:14:11 -0700 Message-ID: <20260928181414.644158-10-ameryhung@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260928181414.644158-1-ameryhung@gmail.com> References: <20260928181414.644158-1-ameryhung@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Route global ARG_PTR_TO_BTF_ID arguments through check_func_arg(). Use vmlinux BTF for their type match and retain the global-subprogram rules instead of applying kfunc-only trusted-pointer validation or runtime type resolution. The common nullability check now rejects non-nullable global BTF-ID arguments before register-type matching. Update the corresponding verifier log expectations. Signed-off-by: Amery Hung --- kernel/bpf/verifier.c | 31 +++++-------------- .../bpf/progs/verifier_global_ptr_args.c | 4 +-- 2 files changed, 10 insertions(+), 25 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index fb0e2649bab3..a39b23864878 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9512,7 +9512,7 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, u32 slot, u32 p case ARG_PTR_TO_BTF_ID_SOCK_COMMON: { const u32 *arg_btf_id = fn->arg_btf_id[arg]; - const struct btf *arg_btf = meta->btf ?: btf_vmlinux; + const struct btf *arg_btf = is_kfunc(meta) ? meta->btf : btf_vmlinux; if (!meta->btf) { const struct bpf_reg_types *compatible; @@ -9540,8 +9540,8 @@ static int check_func_arg(struct bpf_verifier_env *env, u32 arg, u32 slot, u32 p } } - if (meta->btf && (!is_trusted_reg(env, reg) || - bpf_type_has_unsafe_modifiers(reg->type))) { + if (is_kfunc(meta) && (!is_trusted_reg(env, reg) || + bpf_type_has_unsafe_modifiers(reg->type))) { if (!(arg_type & MEM_RCU)) { const char *actual_type, *arg_name, *expected_type; @@ -10817,6 +10817,8 @@ static void gen_subprog_arg_proto(const struct bpf_subprog_info *sub, const stru arg_type = ARG_IGNORE; } else if (base_type(arg_type) == ARG_PTR_TO_ARENA) { arg_type |= PTR_MAYBE_NULL; + } else if (base_type(arg_type) == ARG_PTR_TO_BTF_ID) { + proto->arg_btf_id[arg] = &sub->args[slot].btf_id; } proto->arg_type[arg] = arg_type; t = btf_type_skip_modifiers(btf, args[arg].type, NULL); @@ -10883,7 +10885,8 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog, if (arg_type == ARG_SCALAR || arg_type == ARG_IGNORE || arg_type == ARG_PTR_TO_CTX || arg_type == ARG_PTR_TO_DYNPTR || - base_type(arg_type) == ARG_PTR_TO_ARENA) { + base_type(arg_type) == ARG_PTR_TO_ARENA || + base_type(arg_type) == ARG_PTR_TO_BTF_ID) { ret = check_func_arg(env, arg, slot, 0, &meta, env->insn_idx); if (ret) return ret; @@ -10911,24 +10914,6 @@ static int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog, reg_arg_name(env, argno)); return -EINVAL; } - } else if (base_type(arg_type) == ARG_PTR_TO_BTF_ID) { - int err; - - if (bpf_register_is_null(reg) && type_may_be_null(arg_type)) { - err = mark_arg_precision(env, argno); - if (err) - return err; - continue; - } - - err = check_reg_type(env, reg, argno, arg_type, &meta); - err = err ?: check_func_arg_reg_off(env, reg, argno, arg_type); - if (!err && base_type(reg->type) == PTR_TO_BTF_ID) - err = process_arg_ptr_to_btf_id(env, reg, argno, arg_type, - btf_vmlinux, sub->args[slot].btf_id, - &meta, env->insn_idx); - if (err) - return err; } else { verifier_bug(env, "unrecognized %s type %d", reg_arg_name(env, argno), arg_type); @@ -13073,7 +13058,7 @@ static int resolve_func_arg_type(struct bpf_verifier_env *env, if (base_type(*arg_type) != ARG_PTR_TO_BTF_ID) return 0; - if (!meta->btf || arg_type_is_release(*arg_type) || + if (!is_kfunc(meta) || arg_type_is_release(*arg_type) || base_type(reg->type) == PTR_TO_BTF_ID || reg2btf_ids[base_type(reg->type)]) return 0; diff --git a/tools/testing/selftests/bpf/progs/verifier_global_ptr_args.c b/tools/testing/selftests/bpf/progs/verifier_global_ptr_args.c index 10019af5eb74..f639e2767e35 100644 --- a/tools/testing/selftests/bpf/progs/verifier_global_ptr_args.c +++ b/tools/testing/selftests/bpf/progs/verifier_global_ptr_args.c @@ -87,7 +87,7 @@ __weak int subprog_trusted_task_nonnull(struct task_struct *task __arg_trusted) SEC("?kprobe") __failure __log_level(2) -__msg("R1 type=scalar expected=ptr_, trusted_ptr_, rcu_ptr_") +__msg("Possibly NULL pointer passed to trusted R1") __msg("Caller passes invalid args into func#1 ('subprog_trusted_task_nonnull')") int trusted_task_arg_nonnull_fail1(void *ctx) { @@ -96,7 +96,7 @@ int trusted_task_arg_nonnull_fail1(void *ctx) SEC("?tp_btf/task_newtask") __failure __log_level(2) -__msg("R1 type=trusted_ptr_or_null_ expected=ptr_, trusted_ptr_, rcu_ptr_") +__msg("Possibly NULL pointer passed to trusted R1") __msg("Caller passes invalid args into func#1 ('subprog_trusted_task_nonnull')") int trusted_task_arg_nonnull_fail2(void *ctx) { -- 2.52.0