diff options
| -rw-r--r-- | kernel/bpf/btf.c | 7 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 61 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/exceptions_fail.c | 2 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/test_global_func7.c | 2 |
4 files changed, 60 insertions, 12 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 4872d2a6c42d..09fcbb125155 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -7836,15 +7836,16 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) tname, nargs, MAX_BPF_FUNC_REG_ARGS); return -EINVAL; } - /* check that function returns int, exception cb also requires this */ + /* check that function is void or returns int, exception cb also requires this */ t = btf_type_by_id(btf, t->type); while (btf_type_is_modifier(t)) t = btf_type_by_id(btf, t->type); - if (!btf_type_is_int(t) && !btf_is_any_enum(t)) { + if (!btf_type_is_void(t) && !btf_type_is_int(t) && !btf_is_any_enum(t)) { if (!is_global) return -EINVAL; bpf_log(log, - "Global function %s() doesn't return scalar. Only those are supported.\n", + "Global function %s() return value not void or scalar. " + "Only those are supported.\n", tname); return -EINVAL; } diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f66080e88187..d92cf2821657 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -444,6 +444,29 @@ static bool subprog_is_global(const struct bpf_verifier_env *env, int subprog) return aux && aux[subprog].linkage == BTF_FUNC_GLOBAL; } +static bool subprog_returns_void(struct bpf_verifier_env *env, int subprog) +{ + const struct btf_type *type, *func, *func_proto; + const struct btf *btf = env->prog->aux->btf; + u32 btf_id; + + btf_id = env->prog->aux->func_info[subprog].type_id; + + func = btf_type_by_id(btf, btf_id); + if (verifier_bug_if(!func, env, "btf_id %u not found", btf_id)) + return false; + + func_proto = btf_type_by_id(btf, func->type); + if (!func_proto) + return false; + + type = btf_type_skip_modifiers(btf, func_proto->type, NULL); + if (!type) + return false; + + return btf_type_is_void(type); +} + static const char *subprog_name(const struct bpf_verifier_env *env, int subprog) { struct bpf_func_info *info; @@ -10889,9 +10912,11 @@ static int check_func_call(struct bpf_verifier_env *env, struct bpf_insn *insn, subprog_aux(env, subprog)->called = true; clear_caller_saved_regs(env, caller->regs); - /* All global functions return a 64-bit SCALAR_VALUE */ - mark_reg_unknown(env, caller->regs, BPF_REG_0); - caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG; + /* All non-void global functions return a 64-bit SCALAR_VALUE. */ + if (!subprog_returns_void(env, subprog)) { + mark_reg_unknown(env, caller->regs, BPF_REG_0); + caller->regs[BPF_REG_0].subreg_def = DEF_NOT_SUBREG; + } /* continue with next insn after call */ return 0; @@ -17956,7 +17981,7 @@ static bool return_retval_range(struct bpf_verifier_env *env, struct bpf_retval_ static bool program_returns_void(struct bpf_verifier_env *env) { const struct bpf_prog *prog = env->prog; - enum bpf_prog_type prog_type = resolve_prog_type(prog); + enum bpf_prog_type prog_type = prog->type; switch (prog_type) { case BPF_PROG_TYPE_LSM: @@ -17969,6 +17994,16 @@ static bool program_returns_void(struct bpf_verifier_env *env) if (!prog->aux->attach_func_proto->type) return true; break; + case BPF_PROG_TYPE_EXT: + /* + * If the actual program is an extension, let it + * return void - attaching will succeed only if the + * program being replaced also returns void, and since + * it has passed verification its actual type doesn't matter. + */ + if (subprog_returns_void(env, 0)) + return true; + break; default: break; } @@ -18063,8 +18098,12 @@ enforce_retval: static int check_global_subprog_return_code(struct bpf_verifier_env *env) { struct bpf_reg_state *reg = reg_state(env, BPF_REG_0); + struct bpf_func_state *cur_frame = cur_func(env); int err; + if (subprog_returns_void(env, cur_frame->subprogno)) + return 0; + err = check_reg_arg(env, BPF_REG_0, SRC_OP); if (err) return err; @@ -24564,10 +24603,18 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) if (subprog_is_exc_cb(env, subprog)) { state->frame[0]->in_exception_callback_fn = true; - /* We have already ensured that the callback returns an integer, just - * like all global subprogs. We need to determine it only has a single - * scalar argument. + + /* + * Global functions are scalar or void, make sure + * we return a scalar. */ + if (subprog_returns_void(env, subprog)) { + verbose(env, "exception cb cannot return void\n"); + ret = -EINVAL; + goto out; + } + + /* Also ensure the callback only has a single scalar argument. */ if (sub->arg_cnt != 1 || sub->args[0].arg_type != ARG_ANYTHING) { verbose(env, "exception cb only supports single integer argument\n"); ret = -EINVAL; diff --git a/tools/testing/selftests/bpf/progs/exceptions_fail.c b/tools/testing/selftests/bpf/progs/exceptions_fail.c index 8a0fdff89927..d28ecc4ee2d0 100644 --- a/tools/testing/selftests/bpf/progs/exceptions_fail.c +++ b/tools/testing/selftests/bpf/progs/exceptions_fail.c @@ -51,7 +51,7 @@ __noinline int exception_cb_ok_arg_small(int a) SEC("?tc") __exception_cb(exception_cb_bad_ret_type) -__failure __msg("Global function exception_cb_bad_ret_type() doesn't return scalar.") +__failure __msg("Global function exception_cb_bad_ret_type() return value not void or scalar.") int reject_exception_cb_type_1(struct __sk_buff *ctx) { bpf_throw(0); diff --git a/tools/testing/selftests/bpf/progs/test_global_func7.c b/tools/testing/selftests/bpf/progs/test_global_func7.c index f182febfde3c..9e59625c1c92 100644 --- a/tools/testing/selftests/bpf/progs/test_global_func7.c +++ b/tools/testing/selftests/bpf/progs/test_global_func7.c @@ -12,7 +12,7 @@ void foo(struct __sk_buff *skb) } SEC("tc") -__failure __msg("foo() doesn't return scalar") +__success int global_func7(struct __sk_buff *skb) { foo(skb); |