From nobody Fri Dec 19 20:53:05 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 64625C32772 for ; Tue, 23 Aug 2022 09:42:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234181AbiHWJmZ (ORCPT ); Tue, 23 Aug 2022 05:42:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52832 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351676AbiHWJkB (ORCPT ); Tue, 23 Aug 2022 05:40:01 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 451BA98C9E; Tue, 23 Aug 2022 01:41:19 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 55B8861540; Tue, 23 Aug 2022 08:40:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E456C433D6; Tue, 23 Aug 2022 08:40:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661244029; bh=o680fSd5QgG2dGfNBgWcGxeyA9nWVhvUlqlhj7sYoHI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=p1DqDv4j42uJXkt/aSj3FkTEK4SFWS/nbBb1VZiX/1Q0nCXB16iz/YHdyI7Hre+VT Br4ncJWwodvBwNQc0dOxTNu/ON0xdh7wpDg60Kd2R5daVOSWn3G6+rSr8n7kLGLtqK qLqthDCz72z089suhoeM/zC3PMt41qR+hqn+GwQA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jens Axboe , "Jason A. Donenfeld" , Al Viro , Sasha Levin Subject: [PATCH 4.14 075/229] fs: check FMODE_LSEEK to control internal pipe splicing Date: Tue, 23 Aug 2022 10:23:56 +0200 Message-Id: <20220823080056.398968527@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220823080053.202747790@linuxfoundation.org> References: <20220823080053.202747790@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Jason A. Donenfeld [ Upstream commit 97ef77c52b789ec1411d360ed99dca1efe4b2c81 ] The original direct splicing mechanism from Jens required the input to be a regular file because it was avoiding the special socket case. It also recognized blkdevs as being close enough to a regular file. But it forgot about chardevs, which behave the same way and work fine here. This is an okayish heuristic, but it doesn't totally work. For example, a few chardevs should be spliceable here. And a few regular files shouldn't. This patch fixes this by instead checking whether FMODE_LSEEK is set, which represents decently enough what we need rewinding for when splicing to internal pipes. Fixes: b92ce5589374 ("[PATCH] splice: add direct fd <-> fd splicing support= ") Cc: Jens Axboe Signed-off-by: Jason A. Donenfeld Signed-off-by: Al Viro Signed-off-by: Sasha Levin --- fs/splice.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/fs/splice.c b/fs/splice.c index c84ac7e97e21..04d25af25a42 100644 --- a/fs/splice.c +++ b/fs/splice.c @@ -898,17 +898,15 @@ ssize_t splice_direct_to_actor(struct file *in, struc= t splice_desc *sd, { struct pipe_inode_info *pipe; long ret, bytes; - umode_t i_mode; size_t len; int i, flags, more; =20 /* - * We require the input being a regular file, as we don't want to - * randomly drop data for eg socket -> socket splicing. Use the - * piped splicing for that! + * We require the input to be seekable, as we don't want to randomly + * drop data for eg socket -> socket splicing. Use the piped splicing + * for that! */ - i_mode =3D file_inode(in)->i_mode; - if (unlikely(!S_ISREG(i_mode) && !S_ISBLK(i_mode))) + if (unlikely(!(in->f_mode & FMODE_LSEEK))) return -EINVAL; =20 /* --=20 2.35.1