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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 A9656FA3728 for ; Wed, 16 Oct 2019 11:19:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7F0212067B for ; Wed, 16 Oct 2019 11:19:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392731AbfJPLTV (ORCPT ); Wed, 16 Oct 2019 07:19:21 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:40236 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2392706AbfJPLTV (ORCPT ); Wed, 16 Oct 2019 07:19:21 -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 1iKhKp-0003tb-89; Wed, 16 Oct 2019 11:19:19 +0000 From: Christian Brauner To: christian.brauner@ubuntu.com Cc: ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, kafai@fb.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, songliubraving@fb.com, yhs@fb.com, Aleksa Sarai Subject: [PATCH bpf-next v4 3/3] bpf: use copy_struct_from_user() in bpf() syscall Date: Wed, 16 Oct 2019 13:18:10 +0200 Message-Id: <20191016111810.1799-4-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191016111810.1799-1-christian.brauner@ubuntu.com> References: <20191016034432.4418-1-christian.brauner@ubuntu.com> <20191016111810.1799-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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]) copy_struct_from_user(). This helper is intended for all codepaths that copy structs from userspace that are versioned by size. The bpf() syscall does exactly what copy_struct_from_user() is doing. Note that copy_struct_from_user() is calling min() already. So technically, the min_t() call could go. But the size is used further below so leave it. [1]: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper") Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Aleksa Sarai Cc: bpf@vger.kernel.org Signed-off-by: Christian Brauner --- /* v1 */ Link: https://lore.kernel.org/r/20191009160907.10981-4-christian.brauner@ubuntu.com /* v2 */ Link: https://lore.kernel.org/r/20191016004138.24845-4-christian.brauner@ubuntu.com - Alexei Starovoitov : - remove unneeded initialization /* v3 */ Link: https://lore.kernel.org/r/20191016034432.4418-4-christian.brauner@ubuntu.com unchanged /* v4 */ - Alexei Starovoitov : - move misplaced min after copy_struct_from_user() --- kernel/bpf/syscall.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index d554ca7671b6..47bf4a81002d 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2812,21 +2812,18 @@ static int bpf_task_fd_query(const union bpf_attr *attr, SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size) { - union bpf_attr attr = {}; + union bpf_attr attr; int err; if (sysctl_unprivileged_bpf_disabled && !capable(CAP_SYS_ADMIN)) return -EPERM; - err = bpf_check_uarg_tail_zero(uattr, sizeof(attr), size); + /* copy attributes from user space, may be less than sizeof(bpf_attr) */ + err = copy_struct_from_user(&attr, sizeof(attr), uattr, size); if (err) return err; size = min_t(u32, size, sizeof(attr)); - /* copy attributes from user space, may be less than sizeof(bpf_attr) */ - if (copy_from_user(&attr, uattr, size) != 0) - return -EFAULT; - err = security_bpf(cmd, &attr, size); if (err < 0) return err; -- 2.23.0