From patchwork Wed Aug 19 21:59:15 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefano Brivio X-Patchwork-Id: 1348020 X-Patchwork-Delegate: pablo@netfilter.org Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netfilter-devel-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=VLy1kDXu; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BX1sV70CVz9sRN for ; Thu, 20 Aug 2020 07:59:42 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727049AbgHSV7j (ORCPT ); Wed, 19 Aug 2020 17:59:39 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:56992 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726681AbgHSV7h (ORCPT ); Wed, 19 Aug 2020 17:59:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1597874376; h=from:from:reply-to:subject:subject: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=LRVgme0aHZSN40LQ8x3jZkcWqAei3k6qlJ5+ci+N3iI=; b=VLy1kDXubN4utIqIcwNFepeaHIz1U09IaCVsv1sbg/lN1Dx2Mgijb2DdOmwbSFf2V5/1Zz 3G+eeO9C1FV9qkLAoQY8naZb+y5fX/YqUiT7zjzZ+BM+pLFRFzWlyOYOYsa9HVXzMFpjSH t+KdyJcI4V3VvOMex3vespvRBZNMy3U= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-137-AVpSA1TuMV2KfjZ6szk3xg-1; Wed, 19 Aug 2020 17:59:34 -0400 X-MC-Unique: AVpSA1TuMV2KfjZ6szk3xg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 20F51186A574; Wed, 19 Aug 2020 21:59:33 +0000 (UTC) Received: from epycfail.redhat.com (unknown [10.36.110.53]) by smtp.corp.redhat.com (Postfix) with ESMTP id D0F875C1D0; Wed, 19 Aug 2020 21:59:31 +0000 (UTC) From: Stefano Brivio To: Pablo Neira Ayuso Cc: netfilter-devel@vger.kernel.org, Andreas Fischer Subject: [PATCH nf 2/2] nft_set_rbtree: Detect partial overlap with start endpoint match Date: Wed, 19 Aug 2020 23:59:15 +0200 Message-Id: In-Reply-To: References: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Getting creative with nft and omitting the interval_overlap() check from the set_overlap() function, without omitting set_overlap() altogether, led to the observation of a partial overlap that wasn't detected, and would actually result in replacement of the end element of an existing interval. This is due to the fact that we'll return -EEXIST on a matching, pre-existing start element, instead of -ENOTEMPTY, and the error is cleared by API if NLM_F_EXCL is not given. At this point, we can insert a matching start, and duplicate the end element as long as we don't end up into other intervals. For instance, inserting interval 0 - 2 with an existing 0 - 3 interval would result in a single 0 - 2 interval, and a dangling '3' end element. This is because nft will proceed after inserting the '0' start element as no error is reported, and no further conflicting intervals are detected on insertion of the end element. This needs a different approach as it's a local condition that can be detected by looking for duplicate ends coming from left and right, separately. Track those and directly report -ENOTEMPTY on duplicated end elements for a matching start. Signed-off-by: Stefano Brivio --- net/netfilter/nft_set_rbtree.c | 34 +++++++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-) diff --git a/net/netfilter/nft_set_rbtree.c b/net/netfilter/nft_set_rbtree.c index 27668f4e44ea..217ab3644c25 100644 --- a/net/netfilter/nft_set_rbtree.c +++ b/net/netfilter/nft_set_rbtree.c @@ -218,11 +218,11 @@ static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set, struct nft_rbtree_elem *new, struct nft_set_ext **ext) { + bool overlap = false, dup_end_left = false, dup_end_right = false; struct nft_rbtree *priv = nft_set_priv(set); u8 genmask = nft_genmask_next(net); struct nft_rbtree_elem *rbe; struct rb_node *parent, **p; - bool overlap = false; int d; /* Detect overlaps as we descend the tree. Set the flag in these cases: @@ -262,6 +262,20 @@ static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set, * * which always happen as last step and imply that no further * overlapping is possible. + * + * Another special case comes from the fact that start elements matching + * an already existing start element are allowed: insertion is not + * performed but we return -EEXIST in that case, and the error will be + * cleared by the caller if NLM_F_EXCL is not present in the request. + * This way, request for insertion of an exact overlap isn't reported as + * error to userspace if not desired. + * + * However, if the existing start matches a pre-existing start, but the + * end element doesn't match the corresponding pre-existing end element, + * we need to report a partial overlap. This is a local condition that + * can be noticed without need for a tracking flag, by checking for a + * local duplicated end for a corresponding start, from left and right, + * separately. */ parent = NULL; @@ -281,19 +295,35 @@ static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set, !nft_set_elem_expired(&rbe->ext) && !*p) overlap = false; } else { + if (dup_end_left && !*p) + return -ENOTEMPTY; + overlap = nft_rbtree_interval_end(rbe) && nft_set_elem_active(&rbe->ext, genmask) && !nft_set_elem_expired(&rbe->ext); + + if (overlap) { + dup_end_right = true; + continue; + } } } else if (d > 0) { p = &parent->rb_right; if (nft_rbtree_interval_end(new)) { + if (dup_end_right && !*p) + return -ENOTEMPTY; + overlap = nft_rbtree_interval_end(rbe) && nft_set_elem_active(&rbe->ext, genmask) && !nft_set_elem_expired(&rbe->ext); + + if (overlap) { + dup_end_left = true; + continue; + } } else if (nft_set_elem_active(&rbe->ext, genmask) && !nft_set_elem_expired(&rbe->ext)) { overlap = nft_rbtree_interval_end(rbe); @@ -321,6 +351,8 @@ static int __nft_rbtree_insert(const struct net *net, const struct nft_set *set, p = &parent->rb_left; } } + + dup_end_left = dup_end_right = false; } if (overlap)