From patchwork Wed Jun 24 16:13:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11623669 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 1E61290 for ; Wed, 24 Jun 2020 16:15:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF95D206A1 for ; Wed, 24 Jun 2020 16:15:15 +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="WFlQK8lR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404969AbgFXQPO (ORCPT ); Wed, 24 Jun 2020 12:15:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38668 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404800AbgFXQOG (ORCPT ); Wed, 24 Jun 2020 12:14:06 -0400 Received: from casper.infradead.org (unknown [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E9867C061573; Wed, 24 Jun 2020 09:14:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=Hlt6C7VzRXUPvzt04ubxLGUKBtxCCqCnw0SDgIXm7hw=; b=WFlQK8lROlq2wopy0YNuA4PurY T0La8mdHkssAiMiFwrvbcko8YkFtDBrabnQEmr9F5Yk7RFKipkL7CrRypqv3tav+L1chAZbGheAxz 4fxFtgdkmemzU2qnSv3htDLZn56HxForOZfiOkDIrUCuEPwf2+tyREjf20+GZ5x3P+JLpGrterVlQ CG/NQ/tCGzRDoF7SxTM2pcd9onk5riS1Dy7ma9WITzOt6as9RxPS+LWJk+ORBsn8qbKxN3kCu+cd3 sSfwwR5mTlp8wrKC8j7Drm49Isnr85P1IGLuIYqt5/Mp0HsWXk9D9F7bsaKJg7zvAhCqXKaiTncc8 yUoxs6IA==; Received: from [2001:4bb8:180:a3:5c7c:8955:539d:955b] (helo=localhost) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jo81w-0005yG-JE; Wed, 24 Jun 2020 16:13:44 +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 06/14] fs: implement kernel_write using __kernel_write Date: Wed, 24 Jun 2020 18:13:27 +0200 Message-Id: <20200624161335.1810359-7-hch@lst.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200624161335.1810359-1-hch@lst.de> References: <20200624161335.1810359-1-hch@lst.de> MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.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 8f9fc05990ae8b..5110cd1e6e2771 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);