From patchwork Wed May 13 06:56:49 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11545217 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 C93C081 for ; Wed, 13 May 2020 06:57:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A804A20784 for ; Wed, 13 May 2020 06:57:57 +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="ddmpe0Cn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730358AbgEMG5W (ORCPT ); Wed, 13 May 2020 02:57:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50604 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730310AbgEMG5T (ORCPT ); Wed, 13 May 2020 02:57:19 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DCD9C061A0C; Tue, 12 May 2020 23:57:19 -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=KaeJEwRFrws3Sr3qqEXI33NXZ5dPCgwGDFfFGJ19P54=; b=ddmpe0CnpS5hTGI3BvsktS/hjS +5N2t4yhisWNhSCpaQig9siB+HfCl1Yd/k+0mOW8gXepcJlQZt9ge4skfIu+IrRDoDIidW2QzZkpN vuloxdXC6+SFg9jbqWXt3lmYInuKOVrjpvTqI3/d/x+Jf90ccs1Cm5K5FtSx7ZVhxfUjaMazTwKhl Vh1ul/8U/6pCqz4Jg5r5HGPTmdkBIMs7dVLAP/fhFDrOiqLYvAgh3LPwYg5iu3x+QmFIXNNlH6GiV Ss32GP7NZOR4ZJvMuhGNGAewSvAZXihH5Yk/ZUUDdrUcObpvScwAEr/SOus5CyBV13zmwhsyWc3I4 oIc33EGg==; Received: from [2001:4bb8:180:9d3f:c70:4a89:bc61:2] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jYlKO-0003YE-Rp; Wed, 13 May 2020 06:57:17 +0000 From: Christoph Hellwig To: Al Viro Cc: 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: Wed, 13 May 2020 08:56:49 +0200 Message-Id: <20200513065656.2110441-8-hch@lst.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200513065656.2110441-1-hch@lst.de> References: <20200513065656.2110441-1-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);