From patchwork Mon Jun 15 12:12:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11604657 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 7AEEB912 for ; Mon, 15 Jun 2020 12:13:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5A11C206D7 for ; Mon, 15 Jun 2020 12:13:23 +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="PplWXNk6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728510AbgFOMNW (ORCPT ); Mon, 15 Jun 2020 08:13:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729868AbgFOMNT (ORCPT ); Mon, 15 Jun 2020 08:13:19 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A5DA2C061A0E; Mon, 15 Jun 2020 05:13:19 -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=ZbaBcuk5JEiQynZOdgILty6nImhbTO8PWIKxcr9jXUI=; b=PplWXNk6ecjBwXWk5w42Iu/Gir kwKzwlPF8ijEvKAmPw8Eva2egr95FfYdhQrrNFttpWET7omAVVKbnRH7qoblPQig4/S1yCGptRKIy K5HwFDO8kb13Bg6HSU0cJHH/bEE9OkiT8hCGP0yn8MfDEANSdf4jNCgo8ZfZ6pSv0u0yw3HtDB8Zg b997ssPJ1cOXJMn8MhnW/gvI/EoOA/+2NK+7vQOfR/F2Yylxneo7iNRID0Rf7bIut+YhkhmVSxi4I rAC/Cmadm/2MenHINrer1NZCwRX7AxFdTNv5rz9RRNpXwZoRKZW7t8XgjmpIpHZFY3nEV6AUwtxR6 kAR/J1iA==; Received: from 195-192-102-148.dyn.cablelink.at ([195.192.102.148] helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jknzI-00071O-UW; Mon, 15 Jun 2020 12:13:17 +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 06/13] fs: implement kernel_write using __kernel_write Date: Mon, 15 Jun 2020 14:12:50 +0200 Message-Id: <20200615121257.798894-7-hch@lst.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200615121257.798894-1-hch@lst.de> References: <20200615121257.798894-1-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 76be155ad98242..9d50d3cec017d8 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);