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 B75A2C43618 for ; Sat, 1 May 2021 04:31:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 96E3D611CB for ; Sat, 1 May 2021 04:31:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231640AbhEAEb7 (ORCPT ); Sat, 1 May 2021 00:31:59 -0400 Received: from smtp-fw-6002.amazon.com ([52.95.49.90]:65315 "EHLO smtp-fw-6002.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229908AbhEAEb5 (ORCPT ); Sat, 1 May 2021 00:31:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1619843468; x=1651379468; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=8MKTr/lyehjvhaMDltC2LTfEd1bLus4jJ+YK0dVW6nE=; b=c0XQDBXSkQyOG6UjvBzqc0IA0nXrVyBD0F+jb7GOfaS76X+FTs5j59B5 F5pasP+ybHrBHL9atZM1gz6IdmNXF/0Cw1mAu422gMRw42Nsmn1DTafyy HVL+JnaJUazQQy3oaKIF/T9N/oaMs4vMbTAoYpkVD3Bq5FmA+E22O5k+d 4=; X-IronPort-AV: E=Sophos;i="5.82,264,1613433600"; d="scan'208";a="109535172" Received: from iad12-co-svc-p1-lb1-vlan2.amazon.com (HELO email-inbound-relay-1a-715bee71.us-east-1.amazon.com) ([10.43.8.2]) by smtp-border-fw-6002.iad6.amazon.com with ESMTP; 01 May 2021 04:31:05 +0000 Received: from EX13MTAUWB001.ant.amazon.com (iad12-ws-svc-p26-lb9-vlan2.iad.amazon.com [10.40.163.34]) by email-inbound-relay-1a-715bee71.us-east-1.amazon.com (Postfix) with ESMTPS id 7978BA24EC; Sat, 1 May 2021 04:31:03 +0000 (UTC) Received: from EX13D01UWB004.ant.amazon.com (10.43.161.157) by EX13MTAUWB001.ant.amazon.com (10.43.161.249) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sat, 1 May 2021 04:30:17 +0000 Received: from EX13MTAUEA001.ant.amazon.com (10.43.61.82) by EX13d01UWB004.ant.amazon.com (10.43.161.157) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Sat, 1 May 2021 04:30:16 +0000 Received: from dev-dsk-fllinden-2c-d7720709.us-west-2.amazon.com (172.19.206.175) by mail-relay.amazon.com (10.43.61.243) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Sat, 1 May 2021 04:30:16 +0000 Received: by dev-dsk-fllinden-2c-d7720709.us-west-2.amazon.com (Postfix, from userid 6262777) id 441B597F; Sat, 1 May 2021 04:30:14 +0000 (UTC) From: Frank van der Linden To: CC: , , , , , Subject: [PATCH 4.14 08/15] bpf: Refactor and streamline bounds check into helper Date: Sat, 1 May 2021 04:30:07 +0000 Message-ID: <20210501043014.33300-9-fllinden@amazon.com> X-Mailer: git-send-email 2.23.4 In-Reply-To: <20210501043014.33300-1-fllinden@amazon.com> References: <20210501043014.33300-1-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 Upstream commit 073815b756c51ba9d8384d924c5d1c03ca3d1ae4 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 4.14] 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 97a2e4347fe2..55ac2ab5eabc 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2206,6 +2206,41 @@ 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("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)) { + verbose("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 @@ -2421,23 +2456,8 @@ 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)) { - verbose("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("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