From mboxrd@z Thu Jan 1 00:00:00 1970 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=-19.1 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, URIBL_BLOCKED,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 E6A63C47080 for ; Mon, 31 May 2021 13:43:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD2EC619AA for ; Mon, 31 May 2021 13:43:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231751AbhEaNoq (ORCPT ); Mon, 31 May 2021 09:44:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:38922 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232191AbhEaNbJ (ORCPT ); Mon, 31 May 2021 09:31:09 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D14826142E; Mon, 31 May 2021 13:23:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1622467400; bh=p6cLJTjBbWJrCh6BA1GvOygyue4zAN+JyeRS/ZfY4f4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qSQTrItL7VSE6aPmj4HglJMvYUBqbiOVIou91iqaMpCFc9LRd7qWZIVhUvndXM9h7 uZfzYk1WOFA4sgTjeDKWhA9g/dSPduVpWlkS4phMRy6T9YfdNHh7snIeU0XqL/CBDe 51b5ZhbAXnnD+QTIE8j8qgvI4Gofe8Zh5MJBz20E= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Daniel Borkmann , John Fastabend , Alexei Starovoitov , Frank van der Linden , Ovidiu Panait Subject: [PATCH 4.19 051/116] bpf: Refactor and streamline bounds check into helper Date: Mon, 31 May 2021 15:13:47 +0200 Message-Id: <20210531130641.904240396@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210531130640.131924542@linuxfoundation.org> References: <20210531130640.131924542@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Daniel Borkmann commit 073815b756c51ba9d8384d924c5d1c03ca3d1ae4 upstream. Move the bounds check in adjust_ptr_min_max_vals() into a small helper named sanitize_check_bounds() in order to simplify the former a bit. Signed-off-by: Daniel Borkmann Reviewed-by: John Fastabend Acked-by: Alexei Starovoitov [fllinden@amazon.com: backport to 5.4] Signed-off-by: Frank van der Linden Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ovidiu Panait Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/verifier.c | 54 ++++++++++++++++++++++++++++++++++---------------- 1 file changed, 37 insertions(+), 17 deletions(-) --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2911,6 +2911,41 @@ static int sanitize_err(struct bpf_verif return -EACCES; } +static int sanitize_check_bounds(struct bpf_verifier_env *env, + const struct bpf_insn *insn, + const struct bpf_reg_state *dst_reg) +{ + u32 dst = insn->dst_reg; + + /* For unprivileged we require that resulting offset must be in bounds + * in order to be able to sanitize access later on. + */ + if (env->allow_ptr_leaks) + return 0; + + switch (dst_reg->type) { + case PTR_TO_STACK: + if (check_stack_access(env, dst_reg, dst_reg->off + + dst_reg->var_off.value, 1)) { + verbose(env, "R%d stack pointer arithmetic goes out of range, " + "prohibited for !root\n", dst); + return -EACCES; + } + break; + case PTR_TO_MAP_VALUE: + if (check_map_access(env, dst, dst_reg->off, 1, false)) { + verbose(env, "R%d pointer arithmetic of map value goes out of range, " + "prohibited for !root\n", dst); + return -EACCES; + } + break; + default: + break; + } + + return 0; +} + /* Handles arithmetic on a pointer and a scalar: computes new min/max and var_off. * Caller should also handle BPF_MOV case separately. * If we return -EACCES, caller may want to try again treating pointer as a @@ -3118,23 +3153,8 @@ static int adjust_ptr_min_max_vals(struc __reg_deduce_bounds(dst_reg); __reg_bound_offset(dst_reg); - /* For unprivileged we require that resulting offset must be in bounds - * in order to be able to sanitize access later on. - */ - if (!env->allow_ptr_leaks) { - if (dst_reg->type == PTR_TO_MAP_VALUE && - check_map_access(env, dst, dst_reg->off, 1, false)) { - verbose(env, "R%d pointer arithmetic of map value goes out of range, " - "prohibited for !root\n", dst); - return -EACCES; - } else if (dst_reg->type == PTR_TO_STACK && - check_stack_access(env, dst_reg, dst_reg->off + - dst_reg->var_off.value, 1)) { - verbose(env, "R%d stack pointer arithmetic goes out of range, " - "prohibited for !root\n", dst); - return -EACCES; - } - } + if (sanitize_check_bounds(env, insn, dst_reg) < 0) + return -EACCES; return 0; }