From patchwork Fri Mar 11 10:35:09 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?b?SsO8cmdlbiBHcm/Dnw==?= X-Patchwork-Id: 12777781 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 04153C433EF for ; Fri, 11 Mar 2022 10:35:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347996AbiCKKge (ORCPT ); Fri, 11 Mar 2022 05:36:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41430 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348015AbiCKKg2 (ORCPT ); Fri, 11 Mar 2022 05:36:28 -0500 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7BA5F1BD988; Fri, 11 Mar 2022 02:35:12 -0800 (PST) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 39DE021900; Fri, 11 Mar 2022 10:35:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1646994911; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=3mp/NTfr1ZRQi2cvIw2K8ve4TPHKPxpsioOPY6Gm7jc=; b=jEF0gJQKcwhTeagwgBdvSlHK36VYwwKZUbqR5ce0nf5w8NliamXW+5XJYokUtbuWWuhBgB 8rKEt/xFMtHs84cFx6WEQp8PD/IfplRPiesklbTvPESwhZqVNC6NFBDRQiZfIVwtX1gnKU r4JvdzxW9L6tOjbi2UUDEDb/R5Qt3hA= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 0D8A613A85; Fri, 11 Mar 2022 10:35:11 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id hhYYAt8lK2JRdgAAMHmgww (envelope-from ); Fri, 11 Mar 2022 10:35:11 +0000 From: Juergen Gross To: xen-devel@lists.xenproject.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Juergen Gross , Greg Kroah-Hartman Subject: [PATCH] xen/usb: harden xen_hcd against malicious backends Date: Fri, 11 Mar 2022 11:35:09 +0100 Message-Id: <20220311103509.12908-1-jgross@suse.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Make sure a malicious backend can't cause any harm other than wrong I/O data. Missing are verification of the request id in a response, sanitizing the reported actual I/O length, and protection against interrupt storms from the backend. Signed-off-by: Juergen Gross --- drivers/usb/host/xen-hcd.c | 57 ++++++++++++++++++++++++++++---------- 1 file changed, 43 insertions(+), 14 deletions(-) diff --git a/drivers/usb/host/xen-hcd.c b/drivers/usb/host/xen-hcd.c index 01db5c767251..3e487baf8422 100644 --- a/drivers/usb/host/xen-hcd.c +++ b/drivers/usb/host/xen-hcd.c @@ -51,6 +51,7 @@ struct vdevice_status { struct usb_shadow { struct xenusb_urb_request req; struct urb *urb; + bool in_flight; }; struct xenhcd_info { @@ -720,6 +721,12 @@ static void xenhcd_gnttab_done(struct xenhcd_info *info, unsigned int id) int nr_segs = 0; int i; + if (!shadow->in_flight) { + xenhcd_set_error(info, "Illegal request id"); + return; + } + shadow->in_flight = false; + nr_segs = shadow->req.nr_buffer_segs; if (xenusb_pipeisoc(shadow->req.pipe)) @@ -803,6 +810,7 @@ static int xenhcd_do_request(struct xenhcd_info *info, struct urb_priv *urbp) info->urb_ring.req_prod_pvt++; info->shadow[id].urb = urb; + info->shadow[id].in_flight = true; RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->urb_ring, notify); if (notify) @@ -931,10 +939,27 @@ static int xenhcd_unlink_urb(struct xenhcd_info *info, struct urb_priv *urbp) return ret; } -static int xenhcd_urb_request_done(struct xenhcd_info *info) +static void xenhcd_res_to_urb(struct xenhcd_info *info, + struct xenusb_urb_response *res, struct urb *urb) +{ + if (unlikely(!urb)) + return; + + if (res->actual_length > urb->transfer_buffer_length) + urb->actual_length = urb->transfer_buffer_length; + else if (res->actual_length < 0) + urb->actual_length = 0; + else + urb->actual_length = res->actual_length; + urb->error_count = res->error_count; + urb->start_frame = res->start_frame; + xenhcd_giveback_urb(info, urb, res->status); +} + +static int xenhcd_urb_request_done(struct xenhcd_info *info, + unsigned int *eoiflag) { struct xenusb_urb_response res; - struct urb *urb; RING_IDX i, rp; __u16 id; int more_to_do = 0; @@ -961,16 +986,12 @@ static int xenhcd_urb_request_done(struct xenhcd_info *info) xenhcd_gnttab_done(info, id); if (info->error) goto err; - urb = info->shadow[id].urb; - if (likely(urb)) { - urb->actual_length = res.actual_length; - urb->error_count = res.error_count; - urb->start_frame = res.start_frame; - xenhcd_giveback_urb(info, urb, res.status); - } + xenhcd_res_to_urb(info, &res, info->shadow[id].urb); } xenhcd_add_id_to_freelist(info, id); + + *eoiflag = 0; } info->urb_ring.rsp_cons = i; @@ -988,7 +1009,7 @@ static int xenhcd_urb_request_done(struct xenhcd_info *info) return 0; } -static int xenhcd_conn_notify(struct xenhcd_info *info) +static int xenhcd_conn_notify(struct xenhcd_info *info, unsigned int *eoiflag) { struct xenusb_conn_response res; struct xenusb_conn_request *req; @@ -1033,6 +1054,8 @@ static int xenhcd_conn_notify(struct xenhcd_info *info) info->conn_ring.req_prod_pvt); req->id = id; info->conn_ring.req_prod_pvt++; + + *eoiflag = 0; } if (rc != info->conn_ring.req_prod_pvt) @@ -1055,14 +1078,19 @@ static int xenhcd_conn_notify(struct xenhcd_info *info) static irqreturn_t xenhcd_int(int irq, void *dev_id) { struct xenhcd_info *info = (struct xenhcd_info *)dev_id; + unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS; - if (unlikely(info->error)) + if (unlikely(info->error)) { + xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS); return IRQ_HANDLED; + } - while (xenhcd_urb_request_done(info) | xenhcd_conn_notify(info)) + while (xenhcd_urb_request_done(info, &eoiflag) | + xenhcd_conn_notify(info, &eoiflag)) /* Yield point for this unbounded loop. */ cond_resched(); + xen_irq_lateeoi(irq, eoiflag); return IRQ_HANDLED; } @@ -1139,9 +1167,9 @@ static int xenhcd_setup_rings(struct xenbus_device *dev, goto fail; } - err = bind_evtchn_to_irq(info->evtchn); + err = bind_evtchn_to_irq_lateeoi(info->evtchn); if (err <= 0) { - xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq"); + xenbus_dev_fatal(dev, err, "bind_evtchn_to_irq_lateeoi"); goto fail; } @@ -1494,6 +1522,7 @@ static struct usb_hcd *xenhcd_create_hcd(struct xenbus_device *dev) for (i = 0; i < XENUSB_URB_RING_SIZE; i++) { info->shadow[i].req.id = i + 1; info->shadow[i].urb = NULL; + info->shadow[i].in_flight = false; } info->shadow[XENUSB_URB_RING_SIZE - 1].req.id = 0x0fff;