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=-19.0 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=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 D5E9EC4361A for ; Thu, 29 Apr 2021 22:08:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B380861463 for ; Thu, 29 Apr 2021 22:08:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229738AbhD2WJc (ORCPT ); Thu, 29 Apr 2021 18:09:32 -0400 Received: from smtp-fw-2101.amazon.com ([72.21.196.25]:24137 "EHLO smtp-fw-2101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229709AbhD2WJ3 (ORCPT ); Thu, 29 Apr 2021 18:09:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1619734123; x=1651270123; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=Q5Wmy2rJXqFyd0X53V31VAHlYVqY4tXEyA9m3dfYAo4=; b=Uf0QC27jQT2DyGrpiUTlg0Q0zYP7+n5C7w5sg/eeDyr/pSivbL6vZVJ8 41dil1FeMrvYWc58J2xbfo0ffXmsqie9oW9ZhL4fXpG+oYEEIWgcYA1KM BdqXcvhoVSohzfAFFxgBaf9g5RscVimhKCypOohk4Xqur+KQxoP4LIwir o=; X-IronPort-AV: E=Sophos;i="5.82,260,1613433600"; d="scan'208";a="106383182" Received: from iad12-co-svc-p1-lb1-vlan2.amazon.com (HELO email-inbound-relay-2a-69849ee2.us-west-2.amazon.com) ([10.43.8.2]) by smtp-border-fw-2101.iad2.amazon.com with ESMTP; 29 Apr 2021 22:08:41 +0000 Received: from EX13MTAUEB002.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan2.pdx.amazon.com [10.236.137.194]) by email-inbound-relay-2a-69849ee2.us-west-2.amazon.com (Postfix) with ESMTPS id DEBACA1DC1; Thu, 29 Apr 2021 22:08:40 +0000 (UTC) Received: from EX13D25UEB001.ant.amazon.com (10.43.60.30) by EX13MTAUEB002.ant.amazon.com (10.43.60.12) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 29 Apr 2021 22:08:40 +0000 Received: from EX13MTAUEB002.ant.amazon.com (10.43.60.12) by EX13D25UEB001.ant.amazon.com (10.43.60.30) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Thu, 29 Apr 2021 22:08:40 +0000 Received: from dev-dsk-fllinden-2c-d7720709.us-west-2.amazon.com (172.19.206.175) by mail-relay.amazon.com (10.43.60.234) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Thu, 29 Apr 2021 22:08:40 +0000 Received: by dev-dsk-fllinden-2c-d7720709.us-west-2.amazon.com (Postfix, from userid 6262777) id D2CAADE; Thu, 29 Apr 2021 22:08:39 +0000 (UTC) From: Frank van der Linden To: CC: Subject: [PATCH 5.4 5/8] bpf: Refactor and streamline bounds check into helper Date: Thu, 29 Apr 2021 22:08:36 +0000 Message-ID: <20210429220839.15667-6-fllinden@amazon.com> X-Mailer: git-send-email 2.23.4 In-Reply-To: <20210429220839.15667-1-fllinden@amazon.com> References: <20210429220839.15667-1-fllinden@amazon.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: bpf@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 --- kernel/bpf/verifier.c | 54 +++++++++++++++++++++++++++++-------------- 1 file changed, 37 insertions(+), 17 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 59718101fd04..fc33aed59333 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4448,6 +4448,41 @@ static int sanitize_err(struct bpf_verifier_env *env, 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 @@ -4664,23 +4699,8 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, __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; } -- 2.23.3