From patchwork Thu May 28 05:40:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11574735 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 3D412913 for ; Thu, 28 May 2020 05:41:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2540F2089D for ; Thu, 28 May 2020 05:41:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Mol6D5Y6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728000AbgE1FlJ (ORCPT ); Thu, 28 May 2020 01:41:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727987AbgE1FlH (ORCPT ); Thu, 28 May 2020 01:41:07 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5DAB0C05BD1E; Wed, 27 May 2020 22:41:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender :Reply-To:Content-Type:Content-ID:Content-Description; bh=KaeJEwRFrws3Sr3qqEXI33NXZ5dPCgwGDFfFGJ19P54=; b=Mol6D5Y6R1D9e/F+LW7O82xptB MXB9jwA/QH+Hy8SHPKIE9AY9NCg51MAr4nUECczMrcFA59wgSqI56QKnTwMKW8xnVPTIvWueF3Vjj wUjh9xIDDhLot3gscNRfjixZC3vxMYAXKIYdFh2na+jSY2GxnKgpVrj5s0hDa0x8x2/zYfI3y3C5D 9tG6RDPUNrJN50tE6EuOyTdH7CpXpQuolVZVJkyGt3GRsQBsVAQqfsgNcbnPrwZKWOB4LR/EdllWc HLmPUy75V5oNVKaiRQ8gc15+2dI5tvYkt/SivPutaMVICY8GnP5Z+EHB8elXuF2qm9HZIWk5WlReh 5mZSaSMA==; Received: from p4fdb1ad2.dip0.t-ipconnect.de ([79.219.26.210] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jeBHs-0002Nk-G0; Thu, 28 May 2020 05:41:04 +0000 From: Christoph Hellwig To: Al Viro Cc: Linus Torvalds , Ian Kent , David Howells , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, netfilter-devel@vger.kernel.org Subject: [PATCH 07/14] fs: implement kernel_write using __kernel_write Date: Thu, 28 May 2020 07:40:36 +0200 Message-Id: <20200528054043.621510-8-hch@lst.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200528054043.621510-1-hch@lst.de> References: <20200528054043.621510-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: Consolidate the two in-kernel write helpers to make upcoming changes easier. The only difference are the missing call to rw_verify_area in kernel_write, and an access_ok check that doesn't make sense for kernel buffers to start with. Signed-off-by: Christoph Hellwig --- fs/read_write.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/fs/read_write.c b/fs/read_write.c index f0768313ea010..abb84391cfbc5 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -499,6 +499,7 @@ static ssize_t __vfs_write(struct file *file, const char __user *p, return -EINVAL; } +/* caller is responsible for file_start_write/file_end_write */ ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t *pos) { mm_segment_t old_fs; @@ -528,16 +529,16 @@ ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t ssize_t kernel_write(struct file *file, const void *buf, size_t count, loff_t *pos) { - mm_segment_t old_fs; - ssize_t res; + ssize_t ret; - old_fs = get_fs(); - set_fs(KERNEL_DS); - /* The cast to a user pointer is valid due to the set_fs() */ - res = vfs_write(file, (__force const char __user *)buf, count, pos); - set_fs(old_fs); + ret = rw_verify_area(WRITE, file, pos, count); + if (ret) + return ret; - return res; + file_start_write(file); + ret = __kernel_write(file, buf, count, pos); + file_end_write(file); + return ret; } EXPORT_SYMBOL(kernel_write);