From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7E6F6C433DF for ; Mon, 29 Jun 2020 19:27:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6042F20663 for ; Mon, 29 Jun 2020 19:27:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593458856; bh=siDFv2wBYonOfCEnGvScoWYFodnBr3X6yc4XrIJKW9o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=gkSPnBLeTzV6iHOrjcRYw2wy+qWR+g/nfwiZD2ARXvV4CafWMfhjpsmJZNYONObfY RAdueILO4G57vvR50Rv7mkBD53PT36Hsut6PZpbpPEm6YmwGsCZFB+tfEXCqU06sqg pLpBSLRRJiAo2qotlRp0psRfCQ9Qqa8ivImcXkj0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730345AbgF2T1f (ORCPT ); Mon, 29 Jun 2020 15:27:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:37038 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732666AbgF2TZn (ORCPT ); Mon, 29 Jun 2020 15:25:43 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E332825405; Mon, 29 Jun 2020 15:42:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593445352; bh=siDFv2wBYonOfCEnGvScoWYFodnBr3X6yc4XrIJKW9o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=omi0j0rzDn1rUsCn//77wA55nGr8hG4dws3yBWHPYZ9n2u6d5rznIJeuZCSClYpKI 1U+csIgX8ggK2rrXpLzT5LytVrd9rcyxR9hvT9kdfjySNdReReZ4NEBf5yaVLl1TQQ RaWgO4Mpqlgioxw5hbLbaFYS4pWwUA0yHyLympvQ= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Mauro Carvalho Chehab , Florian Fainelli , Greg Kroah-Hartman Subject: [PATCH 4.9 110/191] media: dvb_frontend: better document the -EPERM condition Date: Mon, 29 Jun 2020 11:38:46 -0400 Message-Id: <20200629154007.2495120-111-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200629154007.2495120-1-sashal@kernel.org> References: <20200629154007.2495120-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.9.229-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-4.9.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 4.9.229-rc1 X-KernelTest-Deadline: 2020-07-01T15:39+00:00 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Mauro Carvalho Chehab commit da5516b5e81d45a96291823620f6c820178dc055 upstream Two readonly ioctls can't be allowed if the frontend device is opened in read only mode. Explain why. Reviewed by: Shuah Khan Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Florian Fainelli Signed-off-by: Greg Kroah-Hartman --- drivers/media/dvb-core/dvb_frontend.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c index a7ba8e200b677..673cefb7230cb 100644 --- a/drivers/media/dvb-core/dvb_frontend.c +++ b/drivers/media/dvb-core/dvb_frontend.c @@ -1925,9 +1925,23 @@ static int dvb_frontend_ioctl(struct file *file, unsigned int cmd, void *parg) return -ENODEV; } - if ((file->f_flags & O_ACCMODE) == O_RDONLY && - (_IOC_DIR(cmd) != _IOC_READ || cmd == FE_GET_EVENT || - cmd == FE_DISEQC_RECV_SLAVE_REPLY)) { + /* + * If the frontend is opened in read-only mode, only the ioctls + * that don't interfere with the tune logic should be accepted. + * That allows an external application to monitor the DVB QoS and + * statistics parameters. + * + * That matches all _IOR() ioctls, except for two special cases: + * - FE_GET_EVENT is part of the tuning logic on a DVB application; + * - FE_DISEQC_RECV_SLAVE_REPLY is part of DiSEqC 2.0 + * setup + * So, those two ioctls should also return -EPERM, as otherwise + * reading from them would interfere with a DVB tune application + */ + if ((file->f_flags & O_ACCMODE) == O_RDONLY + && (_IOC_DIR(cmd) != _IOC_READ + || cmd == FE_GET_EVENT + || cmd == FE_DISEQC_RECV_SLAVE_REPLY)) { up(&fepriv->sem); return -EPERM; } -- 2.25.1