From patchwork Thu Mar 9 18:01:10 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Marchevsky X-Patchwork-Id: 13168034 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 71EECC64EC4 for ; Thu, 9 Mar 2023 18:01:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229874AbjCISBf (ORCPT ); Thu, 9 Mar 2023 13:01:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45092 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230013AbjCISBc (ORCPT ); Thu, 9 Mar 2023 13:01:32 -0500 Received: from mx0a-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 93008FCBC1 for ; Thu, 9 Mar 2023 10:01:31 -0800 (PST) Received: from pps.filterd (m0001303.ppops.net [127.0.0.1]) by m0001303.ppops.net (8.17.1.19/8.17.1.19) with ESMTP id 329GhAlh009978 for ; Thu, 9 Mar 2023 10:01:30 -0800 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=N6RRrPfW88p6zD8OybCQOMZYAQk0Vrnk/4ranf2T+54=; b=K/UdsWpKNCYHmDu2az5d8J4E9NynqQ07u54/VnsDnfMHwu+gDzA1i/WjdaN08plKLmRc NS2PIG9rx1zSIgs6uBtm6uARh3V0c1kma9DtF+U/JYGDo+W2kplsZkQSCLyWn7OGFqd9 CNyjnltvCtI3lOFFjrtyScNSvpiaSRHjb54= Received: from maileast.thefacebook.com ([163.114.130.16]) by m0001303.ppops.net (PPS) with ESMTPS id 3p7k7k8gn3-6 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Thu, 09 Mar 2023 10:01:30 -0800 Received: from ash-exhub204.TheFacebook.com (2620:10d:c0a8:83::4) by ash-exhub203.TheFacebook.com (2620:10d:c0a8:83::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.17; Thu, 9 Mar 2023 10:01:27 -0800 Received: from twshared21709.17.frc2.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.17; Thu, 9 Mar 2023 10:01:27 -0800 Received: by devbig077.ldc1.facebook.com (Postfix, from userid 158236) id C114E18E84D51; Thu, 9 Mar 2023 10:01:16 -0800 (PST) From: Dave Marchevsky To: CC: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Kernel Team , , Dave Marchevsky Subject: [PATCH v1 bpf-next 5/6] bpf: Allow local kptrs to be exchanged via bpf_kptr_xchg Date: Thu, 9 Mar 2023 10:01:10 -0800 Message-ID: <20230309180111.1618459-6-davemarchevsky@fb.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230309180111.1618459-1-davemarchevsky@fb.com> References: <20230309180111.1618459-1-davemarchevsky@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: LmVmbxPt87LzEzt5mwS3O_k9YzP2RVcr X-Proofpoint-ORIG-GUID: LmVmbxPt87LzEzt5mwS3O_k9YzP2RVcr X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-03-09_09,2023-03-09_01,2023-02-09_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net The previous patch added necessary plumbing for verifier and runtime to know what to do with non-kernel PTR_TO_BTF_IDs in map values, but didn't provide any way to get such local kptrs into a map value. This patch modifies verifier handling of bpf_kptr_xchg to allow MEM_ALLOC kptr types. check_reg_type is modified accept MEM_ALLOC-flagged input to bpf_kptr_xchg despite such types not being in btf_ptr_types. This could have been done with a MAYBE_MEM_ALLOC equivalent to MAYBE_NULL, but bpf_kptr_xchg is the only helper that I can forsee using MAYBE_MEM_ALLOC, so keep it special-cased for now. The verifier tags bpf_kptr_xchg retval MEM_ALLOC if and only if the BTF associated with the retval is not kernel BTF. Signed-off-by: Dave Marchevsky --- kernel/bpf/verifier.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index cdf1ba65821b..86291f44bb34 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7123,6 +7123,9 @@ static int check_reg_type(struct bpf_verifier_env *env, u32 regno, if (arg_type & PTR_MAYBE_NULL) type &= ~PTR_MAYBE_NULL; + if (meta->func_id == BPF_FUNC_kptr_xchg && type & MEM_ALLOC) + type &= ~MEM_ALLOC; + for (i = 0; i < ARRAY_SIZE(compatible->types); i++) { expected = compatible->types[i]; if (expected == NOT_INIT) @@ -7185,7 +7188,8 @@ static int check_reg_type(struct bpf_verifier_env *env, u32 regno, break; } case PTR_TO_BTF_ID | MEM_ALLOC: - if (meta->func_id != BPF_FUNC_spin_lock && meta->func_id != BPF_FUNC_spin_unlock) { + if (meta->func_id != BPF_FUNC_spin_lock && meta->func_id != BPF_FUNC_spin_unlock && + meta->func_id != BPF_FUNC_kptr_xchg) { verbose(env, "verifier internal error: unimplemented handling of MEM_ALLOC\n"); return -EFAULT; } @@ -9151,6 +9155,8 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn if (func_id == BPF_FUNC_kptr_xchg) { ret_btf = meta.kptr_field->kptr.btf; ret_btf_id = meta.kptr_field->kptr.btf_id; + if (!btf_is_kernel(ret_btf)) + regs[BPF_REG_0].type |= MEM_ALLOC; } else { if (fn->ret_btf_id == BPF_PTR_POISON) { verbose(env, "verifier internal error:");