From patchwork Mon Jun 15 12:12:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11604691 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 AEF81912 for ; Mon, 15 Jun 2020 12:14:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9649E206D7 for ; Mon, 15 Jun 2020 12:14:30 +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="cE84tygu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729908AbgFOMOX (ORCPT ); Mon, 15 Jun 2020 08:14:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729868AbgFOMN0 (ORCPT ); Mon, 15 Jun 2020 08:13:26 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F5C1C061A0E; Mon, 15 Jun 2020 05:13:26 -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=VBVeuzuM0P2q7W7ljlXXpDeFT/LdXFSEK3FuQYaqgbw=; b=cE84tygumZOTSk2LdOM0spcCKt h0fdezrVYR70UorfbR2STjeuuNJx0mibOd3HntKUaw8UYL1v+oHSsAzuaZNgOPDBKlNtUZxpn6NMi A5FtaDTwAbPmExJgOxJ1YZsasH3kb6cmLgl5NmLGAwFkY2xUuRgBuVusurSTe+YejKlNGsPQV3PSz dFwxqVAQhdVWSQC6rToszDj6EifTUtdZsSNBwu98fgxYgau2H7K5+podse+cgEXcJiWBwAjZmM9UL /cgW9z7pFcu6KfZUHJTKf3lEtgi1dTdpcB3Aw2hCcQgqEhyt9bD0nb869ecwvg/EythVDYR58lK2l xDGs//4Q==; 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 1jknzP-00072p-68; Mon, 15 Jun 2020 12:13:23 +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 08/13] fs: don't change the address limit for ->write_iter in __kernel_write Date: Mon, 15 Jun 2020 14:12:52 +0200 Message-Id: <20200615121257.798894-9-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: If we write to a file that implements ->write_iter there is no need to change the address limit if we send a kvec down. Implement that case, and prefer it over using plain ->write with a changed address limit if available. Signed-off-by: Christoph Hellwig --- fs/read_write.c | 31 ++++++++++++++++++++----------- 1 file changed, 20 insertions(+), 11 deletions(-) diff --git a/fs/read_write.c b/fs/read_write.c index f81e15c95f576c..4fb7966f023526 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -491,8 +491,6 @@ static ssize_t new_sync_write(struct file *filp, const char __user *buf, size_t /* 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; - const char __user *p; ssize_t ret; if (!(file->f_mode & FMODE_WRITE)) @@ -500,18 +498,29 @@ ssize_t __kernel_write(struct file *file, const void *buf, size_t count, loff_t if (!(file->f_mode & FMODE_CAN_WRITE)) return -EINVAL; - old_fs = get_fs(); - set_fs(KERNEL_DS); - p = (__force const char __user *)buf; if (count > MAX_RW_COUNT) count = MAX_RW_COUNT; - if (file->f_op->write) - ret = file->f_op->write(file, p, count, pos); - else if (file->f_op->write_iter) - ret = new_sync_write(file, p, count, pos); - else + if (file->f_op->write_iter) { + struct kvec iov = { .iov_base = (void *)buf, .iov_len = count }; + struct kiocb kiocb; + struct iov_iter iter; + + init_sync_kiocb(&kiocb, file); + kiocb.ki_pos = *pos; + iov_iter_kvec(&iter, WRITE, &iov, 1, count); + ret = file->f_op->write_iter(&kiocb, &iter); + if (ret > 0) + *pos = kiocb.ki_pos; + } else if (file->f_op->write) { + mm_segment_t old_fs = get_fs(); + + set_fs(KERNEL_DS); + ret = file->f_op->write(file, (__force const char __user *)buf, + count, pos); + set_fs(old_fs); + } else { ret = -EINVAL; - set_fs(old_fs); + } if (ret > 0) { fsnotify_modify(file); add_wchar(current, ret);