From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.netfilter.org (mail.netfilter.org [217.70.190.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7B96133AD8B; Tue, 25 Nov 2025 22:33:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.190.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764110016; cv=none; b=X64QNzm2TV6tW50TDIHbIOUYTaZSzR80I9PVgl31mLHHir3paYEzUImqr2n30EosfdM10FrxJCNZYxqICy5PvaJ3UpNqYSCf7FrqHdwrPwrJHw+U0be4vqI5Wxjjk7Bj/JKX5CUhA3O0g6JC9fN7J17CiP4DXcJINp+njRGRLm8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764110016; c=relaxed/simple; bh=KPOQ2bYFxIG9+WByVpISt0rOpPa2CfcFOUAPdpYjvW0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=D9liWuwOyd8k8lE8rDkF5NJfM5EdvgwLiUGogBN2xfYsfR3SiODN/WSmNQqacryuY0U3VbHlAd8JJnH3qYfnqCbpzDEYBA7Kjvvc2o9frnMZhHWChihtD9h8qXbv/feWsaJecM77joBMgFjDefj7fpSwDR3HQBvHuwFqKR+cIMY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org; spf=pass smtp.mailfrom=netfilter.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b=BZWPKgCf; arc=none smtp.client-ip=217.70.190.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=netfilter.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b="BZWPKgCf" Received: from localhost.localdomain (mail-agni [217.70.190.124]) by mail.netfilter.org (Postfix) with ESMTPSA id 9D13E602B8; Tue, 25 Nov 2025 23:33:32 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org; s=2025; t=1764110013; bh=xE/17Ed/y4QX1/OVT+xBsj7wnIaJPgm1Pdomy8d+388=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BZWPKgCfZCdqB0kD21ltrcnzrN8iBSfSSW9eUwpXqvMTpvyti/stYQyUrNjzykBLj 1h8xmhcxK6fp5Yym0s0xdduOQcKPL3vT0IYy4U3koiLDj/PrjoXfWjbHHgdLGcs8ki e1ZNKpKzg+8mZb71zebcwN1x0QHn9i0D+qve/q3334B+sH6VHkQmM0jtbc86Jj0Qqc noJKKYcwxlVhMLxaYD/x6ZHp546W89xJmjV2phs2vP217M0gdLbxhooHlbjLZwtuBL MAq/wazd98BaW61iETjLdwpDbb+TWvrCrYqm+KuK42FgXdulnfaOzL5LzxT1guRL2K 5DtBf8+tJh/JQ== From: Pablo Neira Ayuso To: netfilter-devel@vger.kernel.org Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, fw@strlen.de, horms@kernel.org Subject: [PATCH net-next 12/16] netfilter: nft_connlimit: update the count if add was skipped Date: Tue, 25 Nov 2025 22:33:08 +0000 Message-ID: <20251125223312.1246891-13-pablo@netfilter.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251125223312.1246891-1-pablo@netfilter.org> References: <20251125223312.1246891-1-pablo@netfilter.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Fernando Fernandez Mancera Connlimit expression can be used for all kind of packets and not only for packets with connection state new. See this ruleset as example: table ip filter { chain input { type filter hook input priority filter; policy accept; tcp dport 22 ct count over 4 counter } } Currently, if the connection count goes over the limit the counter will count the packets. When a connection is closed, the connection count won't decrement as it should because it is only updated for new connections due to an optimization on __nf_conncount_add() that prevents updating the list if the connection is duplicated. To solve this problem, check whether the connection was skipped and if so, update the list. Adjust count_tree() too so the same fix is applied for xt_connlimit. Fixes: 976afca1ceba ("netfilter: nf_conncount: Early exit in nf_conncount_lookup() and cleanup") Closes: https://lore.kernel.org/netfilter/trinity-85c72a88-d762-46c3-be97-36f10e5d9796-1761173693813@3c-app-mailcom-bs12/ Signed-off-by: Fernando Fernandez Mancera Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_conncount.c | 12 ++++++++---- net/netfilter/nft_connlimit.c | 13 +++++++++++-- 2 files changed, 19 insertions(+), 6 deletions(-) diff --git a/net/netfilter/nf_conncount.c b/net/netfilter/nf_conncount.c index eabce7e141f8..81915ef99a83 100644 --- a/net/netfilter/nf_conncount.c +++ b/net/netfilter/nf_conncount.c @@ -179,7 +179,7 @@ static int __nf_conncount_add(struct net *net, if (ct && nf_ct_is_confirmed(ct)) { if (refcounted) nf_ct_put(ct); - return 0; + return -EEXIST; } if ((u32)jiffies == list->last_gc) @@ -408,7 +408,7 @@ insert_tree(struct net *net, int ret; ret = nf_conncount_add_skb(net, skb, l3num, &rbconn->list); - if (ret) + if (ret && ret != -EEXIST) count = 0; /* hotdrop */ else count = rbconn->list.count; @@ -511,10 +511,14 @@ count_tree(struct net *net, /* same source network -> be counted! */ ret = __nf_conncount_add(net, skb, l3num, &rbconn->list); spin_unlock_bh(&rbconn->list.list_lock); - if (ret) + if (ret && ret != -EEXIST) { return 0; /* hotdrop */ - else + } else { + /* -EEXIST means add was skipped, update the list */ + if (ret == -EEXIST) + nf_conncount_gc_list(net, &rbconn->list); return rbconn->list.count; + } } } diff --git a/net/netfilter/nft_connlimit.c b/net/netfilter/nft_connlimit.c index 41770bde39d3..714a59485935 100644 --- a/net/netfilter/nft_connlimit.c +++ b/net/netfilter/nft_connlimit.c @@ -29,8 +29,17 @@ static inline void nft_connlimit_do_eval(struct nft_connlimit *priv, err = nf_conncount_add_skb(nft_net(pkt), pkt->skb, nft_pf(pkt), priv->list); if (err) { - regs->verdict.code = NF_DROP; - return; + if (err == -EEXIST) { + /* Call gc to update the list count if any connection has + * been closed already. This is useful for softlimit + * connections like limiting bandwidth based on a number + * of open connections. + */ + nf_conncount_gc_list(nft_net(pkt), priv->list); + } else { + regs->verdict.code = NF_DROP; + return; + } } count = READ_ONCE(priv->list->count); -- 2.47.3