From patchwork Fri May 8 09:22:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoph Hellwig X-Patchwork-Id: 11536101 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 6F5C7159A for ; Fri, 8 May 2020 09:22:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 56FE2208DB for ; Fri, 8 May 2020 09:22:59 +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="GOOO9v2Q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727838AbgEHJWy (ORCPT ); Fri, 8 May 2020 05:22:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56600 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727812AbgEHJWx (ORCPT ); Fri, 8 May 2020 05:22:53 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F17C9C05BD43; Fri, 8 May 2020 02:22:52 -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=8pX7i8uPtHU7HN4LiIFYJSz1zLla2TEkp0jZ2qu15RI=; b=GOOO9v2QplkrXMye0xGfmThwzE LGK1+j6gYEzDAXuvhQpa/icS2f9t6+y/sGTeDAbK4JB48nRHYec3N3jCxQMp5ZASxOwKtypYCiIRK Vbgj1OUJEBE6WBmO0V8r7rFvcZ50o52awLIsNYLtHAnGRVPckLfIaFQnGqI3v26xkvkXZ4VxVOgz4 PfFZFXHAysCwvDXLM3+BcgTb8Ee2RmT/K3MJbXwSauYE4wznfb6Z5k2dShehfOa0xlZgWaOPGrDMu lWQxBdehatdCSXws7x/KS3vTZ9W61+y8P1jRcDPrSjhQzfW715yqccPAFizZ4Ufa7eTJEtfnjoFgh DDr9S7Pg==; Received: from [2001:4bb8:180:9d3f:90d7:9df8:7cd:3504] (helo=localhost) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWzDY-0000AI-Ek; Fri, 08 May 2020 09:22:52 +0000 From: Christoph Hellwig To: Al Viro Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH 11/11] fs: don't change the address limit for ->read_iter in __kernel_read Date: Fri, 8 May 2020 11:22:22 +0200 Message-Id: <20200508092222.2097-12-hch@lst.de> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200508092222.2097-1-hch@lst.de> References: <20200508092222.2097-1-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 read to a file that implements ->read_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 ->read with a changed address limit if available. Signed-off-by: Christoph Hellwig --- fs/read_write.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) diff --git a/fs/read_write.c b/fs/read_write.c index f0009b506014c..70715a0e2375d 100644 --- a/fs/read_write.c +++ b/fs/read_write.c @@ -421,7 +421,6 @@ static ssize_t new_sync_read(struct file *filp, char __user *buf, size_t len, lo ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos) { - mm_segment_t old_fs = get_fs(); ssize_t ret; if (!(file->f_mode & FMODE_CAN_READ)) @@ -429,14 +428,25 @@ ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos) if (count > MAX_RW_COUNT) count = MAX_RW_COUNT; - set_fs(KERNEL_DS); - if (file->f_op->read) + if (file->f_op->read_iter) { + struct kvec iov = { .iov_base = buf, .iov_len = count }; + struct kiocb kiocb; + struct iov_iter iter; + + init_sync_kiocb(&kiocb, file); + kiocb.ki_pos = *pos; + iov_iter_kvec(&iter, READ, &iov, 1, count); + ret = file->f_op->read_iter(&kiocb, &iter); + *pos = kiocb.ki_pos; + } else if (file->f_op->read) { + mm_segment_t old_fs = get_fs(); + + set_fs(KERNEL_DS); ret = file->f_op->read(file, (void __user *)buf, count, pos); - else if (file->f_op->read_iter) - ret = new_sync_read(file, (void __user *)buf, count, pos); - else + set_fs(old_fs); + } else { ret = -EINVAL; - set_fs(old_fs); + } if (ret > 0) { fsnotify_access(file); add_rchar(current, ret);