From patchwork Thu Jul 8 12:43:44 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?b?SsO8cmdlbiBHcm/Dnw==?= X-Patchwork-Id: 12365139 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=-19.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,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 C1A10C11F66 for ; Thu, 8 Jul 2021 12:43:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9AD1961432 for ; Thu, 8 Jul 2021 12:43:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229659AbhGHMqh (ORCPT ); Thu, 8 Jul 2021 08:46:37 -0400 Received: from smtp-out1.suse.de ([195.135.220.28]:41612 "EHLO smtp-out1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230456AbhGHMqg (ORCPT ); Thu, 8 Jul 2021 08:46:36 -0400 Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (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 0C3DB2198B; Thu, 8 Jul 2021 12:43:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1625748234; 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: in-reply-to:in-reply-to:references:references; bh=P4npa89ZahTLG6OBPNclvRbrcVBcLwXWzLAhBZSh1SY=; b=kQxNjstg82kL4O4ZbGnRoUnxhb1jfiG/cNcdtcWx6GOnVEHDD/BIvDQn1QL50wL2g7eREQ KqL6OG17bCJJPC/EAF6ca9HUJFjNj1LV9M3DbH3D37UtCY2ggjLGBQkostZ7F+AZ7jDqdi 6YlCyZaiFi82VevtT4x4ee0iMGO5qiQ= Received: from imap1.suse-dmz.suse.de (imap1.suse-dmz.suse.de [192.168.254.73]) (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 imap1.suse-dmz.suse.de (Postfix) with ESMTPS id BC119133FE; Thu, 8 Jul 2021 12:43:53 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap1.suse-dmz.suse.de with ESMTPSA id ADi5LAnz5mCCYAAAGKfGzw (envelope-from ); Thu, 08 Jul 2021 12:43:53 +0000 From: Juergen Gross To: xen-devel@lists.xenproject.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Juergen Gross , Konrad Rzeszutek Wilk , =?utf-8?q?Roger_Pau_Monn?= =?utf-8?q?=C3=A9?= , Boris Ostrovsky , Stefano Stabellini , Jens Axboe , Jan Beulich Subject: [PATCH v2 2/3] xen/blkfront: don't take local copy of a request from the ring page Date: Thu, 8 Jul 2021 14:43:44 +0200 Message-Id: <20210708124345.10173-3-jgross@suse.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20210708124345.10173-1-jgross@suse.com> References: <20210708124345.10173-1-jgross@suse.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org In order to avoid a malicious backend being able to influence the local copy of a request build the request locally first and then copy it to the ring page instead of doing it the other way round as today. Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich Acked-by: Roger Pau Monné --- V2: - init variable to avoid potential compiler warning (Jan Beulich) --- drivers/block/xen-blkfront.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 86356014d35e..80701860870a 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -546,7 +546,7 @@ static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo, rinfo->shadow[id].status = REQ_WAITING; rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID; - (*ring_req)->u.rw.id = id; + rinfo->shadow[id].req.u.rw.id = id; return id; } @@ -554,11 +554,12 @@ static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo, static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo) { struct blkfront_info *info = rinfo->dev_info; - struct blkif_request *ring_req; + struct blkif_request *ring_req, *final_ring_req; unsigned long id; /* Fill out a communications ring structure. */ - id = blkif_ring_get_request(rinfo, req, &ring_req); + id = blkif_ring_get_request(rinfo, req, &final_ring_req); + ring_req = &rinfo->shadow[id].req; ring_req->operation = BLKIF_OP_DISCARD; ring_req->u.discard.nr_sectors = blk_rq_sectors(req); @@ -569,8 +570,8 @@ static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_inf else ring_req->u.discard.flag = 0; - /* Keep a private copy so we can reissue requests when recovering. */ - rinfo->shadow[id].req = *ring_req; + /* Copy the request to the ring page. */ + *final_ring_req = *ring_req; return 0; } @@ -703,6 +704,7 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri { struct blkfront_info *info = rinfo->dev_info; struct blkif_request *ring_req, *extra_ring_req = NULL; + struct blkif_request *final_ring_req, *final_extra_ring_req = NULL; unsigned long id, extra_id = NO_ASSOCIATED_ID; bool require_extra_req = false; int i; @@ -747,7 +749,8 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri } /* Fill out a communications ring structure. */ - id = blkif_ring_get_request(rinfo, req, &ring_req); + id = blkif_ring_get_request(rinfo, req, &final_ring_req); + ring_req = &rinfo->shadow[id].req; num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg); num_grant = 0; @@ -798,7 +801,9 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri ring_req->u.rw.nr_segments = num_grant; if (unlikely(require_extra_req)) { extra_id = blkif_ring_get_request(rinfo, req, - &extra_ring_req); + &final_extra_ring_req); + extra_ring_req = &rinfo->shadow[extra_id].req; + /* * Only the first request contains the scatter-gather * list. @@ -840,10 +845,10 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri if (setup.segments) kunmap_atomic(setup.segments); - /* Keep a private copy so we can reissue requests when recovering. */ - rinfo->shadow[id].req = *ring_req; + /* Copy request(s) to the ring page. */ + *final_ring_req = *ring_req; if (unlikely(require_extra_req)) - rinfo->shadow[extra_id].req = *extra_ring_req; + *final_extra_ring_req = *extra_ring_req; if (new_persistent_gnts) gnttab_free_grant_references(setup.gref_head);