From patchwork Fri Jul 22 18:34:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Marchevsky X-Patchwork-Id: 12926741 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3287C433EF for ; Fri, 22 Jul 2022 18:35:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236369AbiGVSfD (ORCPT ); Fri, 22 Jul 2022 14:35:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48250 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236337AbiGVSfC (ORCPT ); Fri, 22 Jul 2022 14:35:02 -0400 Received: from mx0b-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB3EB7D1D0 for ; Fri, 22 Jul 2022 11:35:01 -0700 (PDT) Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 26MC8QaD022622 for ; Fri, 22 Jul 2022 11:35:01 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=jqn5vwtwL09kaoTyW2RH9jm0IjV+NApjPiL6U3y5slE=; b=M35ZnRAglbchLkwNCD9rkiG5sxJbZKJw6QrgK7Ipe335F/b9IrofYyrljVLBuS9JUTjL LxFo8QDHor8dUCsahW3b0PglPlld0lVt08Y8U/NoNOfiJLsfgb06VBh8gTo82xaEX/V0 IwivRifMOLxvK1fv1Mn4tUmcaPzSUxaRrQA= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3hf7fc10es-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 22 Jul 2022 11:35:00 -0700 Received: from twshared22934.08.ash9.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::c) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Fri, 22 Jul 2022 11:34:59 -0700 Received: by devbig077.ldc1.facebook.com (Postfix, from userid 158236) id 256DFAB6F196; Fri, 22 Jul 2022 11:34:47 -0700 (PDT) From: Dave Marchevsky To: CC: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Kernel Team , Tejun Heo , Dave Marchevsky Subject: [RFC PATCH bpf-next 02/11] bpf: Add verifier support for custom callback return range Date: Fri, 22 Jul 2022 11:34:29 -0700 Message-ID: <20220722183438.3319790-3-davemarchevsky@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220722183438.3319790-1-davemarchevsky@fb.com> References: <20220722183438.3319790-1-davemarchevsky@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: udvVe_VaQrm_ktf-Nkqrjr2mlp44skz8 X-Proofpoint-ORIG-GUID: udvVe_VaQrm_ktf-Nkqrjr2mlp44skz8 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-07-22_06,2022-07-21_02,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net X-Patchwork-State: RFC Verifier logic to confirm that a callback function returns 0 or 1 was added in commit 69c087ba6225b ("bpf: Add bpf_for_each_map_elem() helper"). At the time, callback return value was only used to continue or stop iteration. In order to support callbacks with a broader return value range, such as those added further in this series, add a callback_ret_range to bpf_func_state. Verifier's helpers which set in_callback_fn will also set the new field, which the verifier will later use to check return value bounds. Default to tnum_range(0, 1) instead of using tnum_unknown as a sentinel value as the latter would prevent the valid range (0, U64_MAX) being used. Signed-off-by: Dave Marchevsky --- include/linux/bpf_verifier.h | 1 + kernel/bpf/verifier.c | 4 +++- 2 files changed, 4 insertions(+), 1 deletion(-) diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 2e3bad8640dc..9c017575c034 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -237,6 +237,7 @@ struct bpf_func_state { */ u32 async_entry_cnt; bool in_callback_fn; + struct tnum callback_ret_range; bool in_async_callback_fn; /* The following fields should be last. See copy_func_state() */ diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index c5fbaa9f025a..1f50becce141 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1745,6 +1745,7 @@ static void init_func_state(struct bpf_verifier_env *env, state->callsite = callsite; state->frameno = frameno; state->subprogno = subprogno; + state->callback_ret_range = tnum_range(0, 1); init_reg_state(env, state); mark_verifier_state_scratched(env); } @@ -6880,6 +6881,7 @@ static int set_find_vma_callback_state(struct bpf_verifier_env *env, __mark_reg_not_init(env, &callee->regs[BPF_REG_4]); __mark_reg_not_init(env, &callee->regs[BPF_REG_5]); callee->in_callback_fn = true; + callee->callback_ret_range = tnum_range(0, 1); return 0; } @@ -6907,7 +6909,7 @@ static int prepare_func_exit(struct bpf_verifier_env *env, int *insn_idx) caller = state->frame[state->curframe]; if (callee->in_callback_fn) { /* enforce R0 return value range [0, 1]. */ - struct tnum range = tnum_range(0, 1); + struct tnum range = callee->callback_ret_range; if (r0->type != SCALAR_VALUE) { verbose(env, "R0 not a scalar value\n");