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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 1CA15C169C4 for ; Tue, 29 Jan 2019 12:05:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E299F20881 for ; Tue, 29 Jan 2019 12:05:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548763519; bh=Fqgs80eSr6RF928HjQpJUxqvFIR+xDsu1GmPY3DrYrI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=hMmeqBF55Hl+oHBtAQLLFrjGhEzv+0UzhQ7JMYXVhYLEcH6riXiIMMGaosNsZbWhp 9Y+IA8juPz3IKLF8vmg9JZc/AzoEPSSFtyfekYWoDeRYUB3JrCKG3TGCrtHvAHvsqo C+g2QBWF0myvNgX3aDR9XHRtcIxSlb+yQh491s64= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730005AbfA2LmR (ORCPT ); Tue, 29 Jan 2019 06:42:17 -0500 Received: from mail.kernel.org ([198.145.29.99]:59804 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729986AbfA2LmM (ORCPT ); Tue, 29 Jan 2019 06:42:12 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 34F8720856; Tue, 29 Jan 2019 11:42:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548762131; bh=Fqgs80eSr6RF928HjQpJUxqvFIR+xDsu1GmPY3DrYrI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sh4F0pZO8wa52MolCOkNpPHgM+z+rIkklzQjJDNSnvBzT0LoHw9YamEZJ9X5296wJ JqFOIHk1wIc+N3RsF2d/4EJzTLl/O229M/tOFISExBf4qbuHxDYSJdrsHJsUqm4MNo PH+yEc9n/rjBVfDMRMhYY0nxSSu2RS2WGTha4y80= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Borkmann , Alexei Starovoitov , Sasha Levin Subject: [PATCH 4.20 101/117] bpf: restrict unknown scalars of mixed signed bounds for unprivileged Date: Tue, 29 Jan 2019 12:35:52 +0100 Message-Id: <20190129113212.414924803@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190129113207.477505932@linuxfoundation.org> References: <20190129113207.477505932@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.20-stable review patch. If anyone has any objections, please let me know. ------------------ [ commit 9d7eceede769f90b66cfa06ad5b357140d5141ed upstream ] For unknown scalars of mixed signed bounds, meaning their smin_value is negative and their smax_value is positive, we need to reject arithmetic with pointer to map value. For unprivileged the goal is to mask every map pointer arithmetic and this cannot reliably be done when it is unknown at verification time whether the scalar value is negative or positive. Given this is a corner case, the likelihood of breaking should be very small. Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Signed-off-by: Sasha Levin --- kernel/bpf/verifier.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index dc9c57f1a153..8e90e795ca68 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2997,8 +2997,8 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, smin_ptr = ptr_reg->smin_value, smax_ptr = ptr_reg->smax_value; u64 umin_val = off_reg->umin_value, umax_val = off_reg->umax_value, umin_ptr = ptr_reg->umin_value, umax_ptr = ptr_reg->umax_value; + u32 dst = insn->dst_reg, src = insn->src_reg; u8 opcode = BPF_OP(insn->code); - u32 dst = insn->dst_reg; dst_reg = ®s[dst]; @@ -3031,6 +3031,13 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, verbose(env, "R%d pointer arithmetic on %s prohibited\n", dst, reg_type_str[ptr_reg->type]); return -EACCES; + case PTR_TO_MAP_VALUE: + if (!env->allow_ptr_leaks && !known && (smin_val < 0) != (smax_val < 0)) { + verbose(env, "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: break; } -- 2.19.1