From patchwork Mon Apr 19 23:56:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Samuel Mendoza-Jonas X-Patchwork-Id: 424317 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 66F7AC433B4 for ; Mon, 19 Apr 2021 23:57:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3839D61363 for ; Mon, 19 Apr 2021 23:57:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232046AbhDSX6G (ORCPT ); Mon, 19 Apr 2021 19:58:06 -0400 Received: from smtp-fw-9102.amazon.com ([207.171.184.29]:36241 "EHLO smtp-fw-9102.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229471AbhDSX6F (ORCPT ); Mon, 19 Apr 2021 19:58:05 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1618876656; x=1650412656; h=from:to:cc:subject:date:message-id:mime-version; bh=sJXxVXx4KCMJyv3wNLapHiDM+z+uwVIJUTlM2adv4g4=; b=JawrN/FYadVYZh1TnaA/Zb9VqLy/XWqX+SjfCTqB8h4rIwMxtoeB1Bbv mdhQV8l5VywnV/LmcCY89M+nnJ9hGbdj8YchZih3RSjTYlOQ1hG80RtWW YkntuG5PfaCRHEZ9Q9mZ3idS7mfiIBemtzRQO2lvcJZ8AiGgTpGXEoCli g=; X-IronPort-AV: E=Sophos;i="5.82,235,1613433600"; d="scan'208";a="128968883" Received: from pdx4-co-svc-p1-lb2-vlan3.amazon.com (HELO email-inbound-relay-1a-67b371d8.us-east-1.amazon.com) ([10.25.36.214]) by smtp-border-fw-out-9102.sea19.amazon.com with ESMTP; 19 Apr 2021 23:57:35 +0000 Received: from EX13MTAUWA001.ant.amazon.com (iad12-ws-svc-p26-lb9-vlan3.iad.amazon.com [10.40.163.38]) by email-inbound-relay-1a-67b371d8.us-east-1.amazon.com (Postfix) with ESMTPS id 2397FA1BCA; Mon, 19 Apr 2021 23:57:32 +0000 (UTC) Received: from EX13D01UWA002.ant.amazon.com (10.43.160.74) by EX13MTAUWA001.ant.amazon.com (10.43.160.118) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 19 Apr 2021 23:57:32 +0000 Received: from u87e72aa3c6c25c.ant.amazon.com (10.43.161.253) by EX13d01UWA002.ant.amazon.com (10.43.160.74) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Mon, 19 Apr 2021 23:57:31 +0000 From: Samuel Mendoza-Jonas To: CC: , , , Alexei Starovoitov , Daniel Borkmann , Samuel Mendoza-Jonas Subject: [PATCH] bpf: Fix backport of "bpf: restrict unknown scalars of mixed signed bounds for unprivileged" Date: Mon, 19 Apr 2021 16:56:41 -0700 Message-ID: <20210419235641.5442-1-samjonas@amazon.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 X-Originating-IP: [10.43.161.253] X-ClientProxiedBy: EX13D46UWC003.ant.amazon.com (10.43.162.119) To EX13d01UWA002.ant.amazon.com (10.43.160.74) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The 4.14 backport of 9d7eceede ("bpf: restrict unknown scalars of mixed signed bounds for unprivileged") adds the PTR_TO_MAP_VALUE check to the wrong location in adjust_ptr_min_max_vals(), most likely because 4.14 doesn't include the commit that updates the if-statement to a switch-statement (aad2eeaf4 "bpf: Simplify ptr_min_max_vals adjustment"). Move the check to the proper location in adjust_ptr_min_max_vals(). Fixes: 17efa65350c5a ("bpf: restrict unknown scalars of mixed signed bounds for unprivileged") Signed-off-by: Samuel Mendoza-Jonas Reviewed-by: Frank van der Linden Reviewed-by: Ethan Chen Acked-by: Yonghong Song Reviewed-by: Balbir Singh --- kernel/bpf/verifier.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 0c3a9302be93..9e9b7c076bcb 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2204,6 +2204,13 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, dst); return -EACCES; } + if (ptr_reg->type == PTR_TO_MAP_VALUE) { + if (!env->allow_ptr_leaks && !known && (smin_val < 0) != (smax_val < 0)) { + verbose("R%d has unknown scalar with mixed signed bounds, pointer arithmetic with it prohibited for !root\n", + off_reg == dst_reg ? dst : src); + return -EACCES; + } + } /* In case of 'scalar += pointer', dst_reg inherits pointer type and id. * The id may be overwritten later if we create a new variable offset. @@ -2349,13 +2356,6 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, verbose("R%d bitwise operator %s on pointer prohibited\n", dst, bpf_alu_string[opcode >> 4]); return -EACCES; - case PTR_TO_MAP_VALUE: - if (!env->allow_ptr_leaks && !known && (smin_val < 0) != (smax_val < 0)) { - verbose("R%d has unknown scalar with mixed signed bounds, pointer arithmetic with it prohibited for !root\n", - off_reg == dst_reg ? dst : src); - return -EACCES; - } - /* fall-through */ default: /* other operators (e.g. MUL,LSH) produce non-pointer results */ if (!env->allow_ptr_leaks)