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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 53C31C433FE for ; Wed, 8 Sep 2021 12:29:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3A0C960E77 for ; Wed, 8 Sep 2021 12:29:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348576AbhIHMaH (ORCPT ); Wed, 8 Sep 2021 08:30:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60608 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346096AbhIHMaD (ORCPT ); Wed, 8 Sep 2021 08:30:03 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:12e:520::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DCEEC061575 for ; Wed, 8 Sep 2021 05:28:56 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1mNwhC-0004bB-QV; Wed, 08 Sep 2021 14:28:54 +0200 From: Florian Westphal To: Cc: Florian Westphal Subject: [PATCH nf 1/5] netfilter: conntrack: make connection tracking table less predictable Date: Wed, 8 Sep 2021 14:28:34 +0200 Message-Id: <20210908122839.7526-2-fw@strlen.de> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210908122839.7526-1-fw@strlen.de> References: <20210908122839.7526-1-fw@strlen.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Similar to commit 67d6d681e15b ("ipv4: make exception cache less predictible"): Use a random drop length to make it harder to detect when entries were hashed to same bucket list. Signed-off-by: Florian Westphal --- net/netfilter/nf_conntrack_core.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 94e18fb9690d..91b7edaa635c 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -77,7 +77,8 @@ static __read_mostly bool nf_conntrack_locks_all; #define GC_SCAN_INTERVAL (120u * HZ) #define GC_SCAN_MAX_DURATION msecs_to_jiffies(10) -#define MAX_CHAINLEN 64u +#define MIN_CHAINLEN 8u +#define MAX_CHAINLEN (32u - MIN_CHAINLEN) static struct conntrack_gc_work conntrack_gc_work; @@ -842,6 +843,7 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct) unsigned int hash, reply_hash; struct nf_conntrack_tuple_hash *h; struct hlist_nulls_node *n; + unsigned int max_chainlen; unsigned int chainlen = 0; unsigned int sequence; int err = -EEXIST; @@ -857,13 +859,15 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct) &ct->tuplehash[IP_CT_DIR_REPLY].tuple); } while (nf_conntrack_double_lock(net, hash, reply_hash, sequence)); + max_chainlen = MIN_CHAINLEN + prandom_u32_max(MAX_CHAINLEN); + /* See if there's one in the list already, including reverse */ hlist_nulls_for_each_entry(h, n, &nf_conntrack_hash[hash], hnnode) { if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, zone, net)) goto out; - if (chainlen++ > MAX_CHAINLEN) + if (chainlen++ > max_chainlen) goto chaintoolong; } @@ -873,7 +877,7 @@ nf_conntrack_hash_check_insert(struct nf_conn *ct) if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, zone, net)) goto out; - if (chainlen++ > MAX_CHAINLEN) + if (chainlen++ > max_chainlen) goto chaintoolong; } @@ -1103,8 +1107,8 @@ nf_ct_resolve_clash(struct sk_buff *skb, struct nf_conntrack_tuple_hash *h, int __nf_conntrack_confirm(struct sk_buff *skb) { + unsigned int chainlen = 0, sequence, max_chainlen; const struct nf_conntrack_zone *zone; - unsigned int chainlen = 0, sequence; unsigned int hash, reply_hash; struct nf_conntrack_tuple_hash *h; struct nf_conn *ct; @@ -1168,6 +1172,7 @@ __nf_conntrack_confirm(struct sk_buff *skb) goto dying; } + max_chainlen = MIN_CHAINLEN + prandom_u32_max(MAX_CHAINLEN); /* See if there's one in the list already, including reverse: NAT could have grabbed it without realizing, since we're not in the hash. If there is, we lost race. */ @@ -1175,7 +1180,7 @@ __nf_conntrack_confirm(struct sk_buff *skb) if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple, zone, net)) goto out; - if (chainlen++ > MAX_CHAINLEN) + if (chainlen++ > max_chainlen) goto chaintoolong; } @@ -1184,7 +1189,7 @@ __nf_conntrack_confirm(struct sk_buff *skb) if (nf_ct_key_equal(h, &ct->tuplehash[IP_CT_DIR_REPLY].tuple, zone, net)) goto out; - if (chainlen++ > MAX_CHAINLEN) { + if (chainlen++ > max_chainlen) { chaintoolong: nf_ct_add_to_dying_list(ct); NF_CT_STAT_INC(net, chaintoolong); -- 2.32.0