From patchwork Wed Oct 9 16:09:05 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 1173844 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=ubuntu.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 46pK0c3jb2z9s7T for ; Thu, 10 Oct 2019 03:09:20 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731748AbfJIQJS (ORCPT ); Wed, 9 Oct 2019 12:09:18 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:41923 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731452AbfJIQJR (ORCPT ); Wed, 9 Oct 2019 12:09:17 -0400 Received: from [213.220.153.21] (helo=localhost.localdomain) by youngberry.canonical.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1iIEWX-00034Q-5J; Wed, 09 Oct 2019 16:09:13 +0000 From: Christian Brauner To: Alexei Starovoitov , Daniel Borkmann , bpf@vger.kernel.org Cc: Martin KaFai Lau , Song Liu , Yonghong Song , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Christian Brauner Subject: [PATCH 1/3] bpf: use check_zeroed_user() in bpf_check_uarg_tail_zero() Date: Wed, 9 Oct 2019 18:09:05 +0200 Message-Id: <20191009160907.10981-2-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191009160907.10981-1-christian.brauner@ubuntu.com> References: <20191009160907.10981-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In v5.4-rc2 we added a new helper (cf. [1]) check_zeroed_user() which does what bpf_check_uarg_tail_zero() is doing generically. We're slowly switching such codepaths over to use check_zeroed_user() instead of using their own hand-rolled version. [1]: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper") Signed-off-by: Christian Brauner Acked-by: Aleksa Sarai --- kernel/bpf/syscall.c | 22 +++++++--------------- 1 file changed, 7 insertions(+), 15 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 82eabd4e38ad..78790778f101 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -63,30 +63,22 @@ int bpf_check_uarg_tail_zero(void __user *uaddr, size_t expected_size, size_t actual_size) { - unsigned char __user *addr; - unsigned char __user *end; - unsigned char val; + size_t size = min(expected_size, actual_size); + size_t rest = max(expected_size, actual_size) - size; int err; if (unlikely(actual_size > PAGE_SIZE)) /* silly large */ return -E2BIG; - if (unlikely(!access_ok(uaddr, actual_size))) - return -EFAULT; - if (actual_size <= expected_size) return 0; - addr = uaddr + expected_size; - end = uaddr + actual_size; + err = check_zeroed_user(uaddr + expected_size, rest); + if (err < 0) + return err; - for (; addr < end; addr++) { - err = get_user(val, addr); - if (err) - return err; - if (val) - return -E2BIG; - } + if (err) + return -E2BIG; return 0; }