From patchwork Fri Dec 1 18:33:55 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 13476292 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 72F90131 for ; Fri, 1 Dec 2023 10:34:31 -0800 (PST) Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 3B1I9aqp017510 for ; Fri, 1 Dec 2023 10:34:31 -0800 Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3uqbjwkgwc-19 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 01 Dec 2023 10:34:31 -0800 Received: from twshared19681.14.frc2.facebook.com (2620:10d:c085:108::4) by mail.thefacebook.com (2620:10d:c085:21d::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.34; Fri, 1 Dec 2023 10:34:19 -0800 Received: by devbig019.vll3.facebook.com (Postfix, from userid 137359) id 02ADD3C6DB4C5; Fri, 1 Dec 2023 10:34:14 -0800 (PST) From: Andrii Nakryiko To: , , , CC: , , Eduard Zingerman , Shung-Hsi Yu Subject: [PATCH v4 bpf-next 07/11] bpf: unify async callback and program retval checks Date: Fri, 1 Dec 2023 10:33:55 -0800 Message-ID: <20231201183359.1769668-8-andrii@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231201183359.1769668-1-andrii@kernel.org> References: <20231201183359.1769668-1-andrii@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: AIEmV0gaqB7KebpkaRXXRtz9pIGTQP3U X-Proofpoint-ORIG-GUID: AIEmV0gaqB7KebpkaRXXRtz9pIGTQP3U X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.997,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-12-01_16,2023-11-30_01,2023-05-22_02 X-Patchwork-Delegate: bpf@iogearbox.net Use common logic to verify program return values and async callback return values. This allows to avoid duplication of any extra steps necessary, like precision marking, which will be added in the next patch. Acked-by: Eduard Zingerman Acked-by: Shung-Hsi Yu Signed-off-by: Andrii Nakryiko --- kernel/bpf/verifier.c | 30 ++++++++++++------------------ 1 file changed, 12 insertions(+), 18 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9411c1046268..c54944af1bcc 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -367,7 +367,7 @@ static void verbose_invalid_scalar(struct bpf_verifier_env *env, { bool unknown = true; - verbose(env, "At %s the register %s has", ctx, reg_name); + verbose(env, "%s the register %s has", ctx, reg_name); if (reg->smin_value > S64_MIN) { verbose(env, " smin=%lld", reg->smin_value); unknown = false; @@ -9610,7 +9610,7 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) /* enforce R0 return value range */ if (!retval_range_within(callee->callback_ret_range, r0)) { verbose_invalid_scalar(env, r0, callee->callback_ret_range, - "callback return", "R0"); + "At callback return", "R0"); return -EINVAL; } if (!calls_callback(env, callee->callsite)) { @@ -14993,11 +14993,11 @@ static int check_ld_abs(struct bpf_verifier_env *env, struct bpf_insn *insn) static int check_return_code(struct bpf_verifier_env *env, int regno, const char *reg_name) { + const char *exit_ctx = "At program exit"; struct tnum enforce_attach_type_range = tnum_unknown; const struct bpf_prog *prog = env->prog; struct bpf_reg_state *reg; struct bpf_retval_range range = retval_range(0, 1); - struct bpf_retval_range const_0 = retval_range(0, 0); enum bpf_prog_type prog_type = resolve_prog_type(env->prog); int err; struct bpf_func_state *frame = env->cur_state->frame[0]; @@ -15039,17 +15039,9 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char if (frame->in_async_callback_fn) { /* enforce return zero from async callbacks like timer */ - if (reg->type != SCALAR_VALUE) { - verbose(env, "In async callback the register R%d is not a known value (%s)\n", - regno, reg_type_str(env, reg->type)); - return -EINVAL; - } - - if (!retval_range_within(const_0, reg)) { - verbose_invalid_scalar(env, reg, const_0, "async callback", reg_name); - return -EINVAL; - } - return 0; + exit_ctx = "At async callback return"; + range = retval_range(0, 0); + goto enforce_retval; } if (is_subprog && !frame->in_exception_callback_fn) { @@ -15139,15 +15131,17 @@ static int check_return_code(struct bpf_verifier_env *env, int regno, const char return 0; } +enforce_retval: if (reg->type != SCALAR_VALUE) { - verbose(env, "At program exit the register R%d is not a known value (%s)\n", - regno, reg_type_str(env, reg->type)); + verbose(env, "%s the register R%d is not a known value (%s)\n", + exit_ctx, regno, reg_type_str(env, reg->type)); return -EINVAL; } if (!retval_range_within(range, reg)) { - verbose_invalid_scalar(env, reg, range, "program exit", reg_name); - if (prog->expected_attach_type == BPF_LSM_CGROUP && + verbose_invalid_scalar(env, reg, range, exit_ctx, reg_name); + if (!is_subprog && + prog->expected_attach_type == BPF_LSM_CGROUP && prog_type == BPF_PROG_TYPE_LSM && !prog->aux->attach_func_proto->type) verbose(env, "Note, BPF_LSM_CGROUP that attach to void LSM hooks can't modify return value!\n");