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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 EF87FC2D0CE for ; Sun, 29 Dec 2019 17:41:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CB670206A4 for ; Sun, 29 Dec 2019 17:41:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1577641269; bh=a7rI37hFikzC3UaiQXhfFe1YXGRjSfgDaiUuxkZ8SEw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jlosKfDrnxLeyzLZhXl2YnBBt1IbLw1g9t0wtRsdj9PfruFzuo+cwO6H+nLs7EwfK qohRUtkJi8gViu5sr/yNAcn5XK1qKrg+uVCc+ZXVZf+wU1dyAx9QC4DOUIoNLz1sXm T+23gOpSqAAhosOWi2pQ8qIINhavO0nIUvXXhrkk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728608AbfL2RlG (ORCPT ); Sun, 29 Dec 2019 12:41:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:57244 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729027AbfL2Raq (ORCPT ); Sun, 29 Dec 2019 12:30:46 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 27C3520722; Sun, 29 Dec 2019 17:30:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1577640645; bh=a7rI37hFikzC3UaiQXhfFe1YXGRjSfgDaiUuxkZ8SEw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=f/zSKrO42mLPA8NkHh4OkFTajauURw57f18wtpm7Nz4r4oJoqhT9gMXiaNytOQ9cj oEOOxVvymtnlw6zOdri1xikwLTgQ8MUFL/hh1TDrWtWKD/hSc71U3hW9jZNQu1UXMx s1X2/rgXFa7fW+e5DzO6lPgbWyhoFs1TKa54YmwU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ingo Rohloff , Sasha Levin Subject: [PATCH 4.19 079/219] usb: usbfs: Suppress problematic bind and unbind uevents. Date: Sun, 29 Dec 2019 18:18:01 +0100 Message-Id: <20191229162517.692370357@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191229162508.458551679@linuxfoundation.org> References: <20191229162508.458551679@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Ingo Rohloff [ Upstream commit abb0b3d96a1f9407dd66831ae33985a386d4200d ] commit 1455cf8dbfd0 ("driver core: emit uevents when device is bound to a driver") added bind and unbind uevents when a driver is bound or unbound to a physical device. For USB devices which are handled via the generic usbfs layer (via libusb for example), this is problematic: Each time a user space program calls ioctl(usb_fd, USBDEVFS_CLAIMINTERFACE, &usb_intf_nr); and then later ioctl(usb_fd, USBDEVFS_RELEASEINTERFACE, &usb_intf_nr); The kernel will now produce a bind or unbind event, which does not really contain any useful information. This allows a user space program to run a DoS attack against programs which listen to uevents (in particular systemd/eudev/upowerd): A malicious user space program just has to call in a tight loop ioctl(usb_fd, USBDEVFS_CLAIMINTERFACE, &usb_intf_nr); ioctl(usb_fd, USBDEVFS_RELEASEINTERFACE, &usb_intf_nr); With this loop the malicious user space program floods the kernel and all programs listening to uevents with tons of bind and unbind events. This patch suppresses uevents for ioctls USBDEVFS_CLAIMINTERFACE and USBDEVFS_RELEASEINTERFACE. Signed-off-by: Ingo Rohloff Link: https://lore.kernel.org/r/20191011115518.2801-1-ingo.rohloff@lauterbach.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/usb/core/devio.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 29c6414f48f1..00204824bffd 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -739,8 +739,15 @@ static int claimintf(struct usb_dev_state *ps, unsigned int ifnum) intf = usb_ifnum_to_if(dev, ifnum); if (!intf) err = -ENOENT; - else + else { + unsigned int old_suppress; + + /* suppress uevents while claiming interface */ + old_suppress = dev_get_uevent_suppress(&intf->dev); + dev_set_uevent_suppress(&intf->dev, 1); err = usb_driver_claim_interface(&usbfs_driver, intf, ps); + dev_set_uevent_suppress(&intf->dev, old_suppress); + } if (err == 0) set_bit(ifnum, &ps->ifclaimed); return err; @@ -760,7 +767,13 @@ static int releaseintf(struct usb_dev_state *ps, unsigned int ifnum) if (!intf) err = -ENOENT; else if (test_and_clear_bit(ifnum, &ps->ifclaimed)) { + unsigned int old_suppress; + + /* suppress uevents while releasing interface */ + old_suppress = dev_get_uevent_suppress(&intf->dev); + dev_set_uevent_suppress(&intf->dev, 1); usb_driver_release_interface(&usbfs_driver, intf); + dev_set_uevent_suppress(&intf->dev, old_suppress); err = 0; } return err; -- 2.20.1