From patchwork Wed Oct 16 00:41:38 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christian Brauner X-Patchwork-Id: 1177475 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: incoming-bpf@patchwork.ozlabs.org Delivered-To: patchwork-incoming-bpf@bilbo.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=bpf-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 46tD5R4CcRz9sPn for ; Wed, 16 Oct 2019 11:42:03 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390355AbfJPAmC (ORCPT ); Tue, 15 Oct 2019 20:42:02 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:53360 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390304AbfJPAlu (ORCPT ); Tue, 15 Oct 2019 20:41:50 -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 1iKXNr-00065g-Qz; Wed, 16 Oct 2019 00:41:47 +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 v2 3/3] bpf: use copy_struct_from_user() in bpf() syscall Date: Wed, 16 Oct 2019 02:41:38 +0200 Message-Id: <20191016004138.24845-4-christian.brauner@ubuntu.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191016004138.24845-1-christian.brauner@ubuntu.com> References: <20191009160907.10981-1-christian.brauner@ubuntu.com> <20191016004138.24845-1-christian.brauner@ubuntu.com> MIME-Version: 1.0 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@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: bpf@vger.kernel.org Acked-by: Aleksa Sarai Signed-off-by: Christian Brauner --- /* v1 */ Link: https://lore.kernel.org/r/20191009160907.10981-4-christian.brauner@ubuntu.com /* v2 */ - Alexei Starovoitov : - remove unneeded initialization --- kernel/bpf/syscall.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 45524089e15d..5db9887a8f4c 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -2817,20 +2817,17 @@ 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); - 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 = copy_struct_from_user(&attr, sizeof(attr), uattr, size); + if (err) + return err; err = security_bpf(cmd, &attr, size); if (err < 0)