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From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org
Subject: [PATCH 3/5] netfilter: nat: fix src map lookup
Date: Tue, 18 Jul 2017 12:13:57 +0200
Message-ID: <1500372839-6735-4-git-send-email-pablo@netfilter.org> (raw)
In-Reply-To: <1500372839-6735-1-git-send-email-pablo@netfilter.org>

From: Florian Westphal <fw@strlen.de>

When doing initial conversion to rhashtable I replaced the bucket
walk with a single rhashtable_lookup_fast().

When moving to rhlist I failed to properly walk the list of identical
tuples, but that is what is needed for this to work correctly.
The table contains the original tuples, so the reply tuples are all
distinct.

We currently decide that mapping is (not) in range only based on the
first entry, but in case its not we need to try the reply tuple of the
next entry until we either find an in-range mapping or we checked
all the entries.

This bug makes nat core attempt collision resolution while it might be
able to use the mapping as-is.

Fixes: 870190a9ec90 ("netfilter: nat: convert nat bysrc hash to rhashtable")
Reported-by: Jaco Kroon <jaco@uls.co.za>
Tested-by: Jaco Kroon <jaco@uls.co.za>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 net/netfilter/nf_nat_core.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index 832c5a08d9a5..eb541786ccb7 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c
@@ -222,20 +222,21 @@ find_appropriate_src(struct net *net,
 		.tuple = tuple,
 		.zone = zone
 	};
-	struct rhlist_head *hl;
+	struct rhlist_head *hl, *h;
 
 	hl = rhltable_lookup(&nf_nat_bysource_table, &key,
 			     nf_nat_bysource_params);
-	if (!hl)
-		return 0;
 
-	ct = container_of(hl, typeof(*ct), nat_bysource);
+	rhl_for_each_entry_rcu(ct, h, hl, nat_bysource) {
+		nf_ct_invert_tuplepr(result,
+				     &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
+		result->dst = tuple->dst;
 
-	nf_ct_invert_tuplepr(result,
-			     &ct->tuplehash[IP_CT_DIR_REPLY].tuple);
-	result->dst = tuple->dst;
+		if (in_range(l3proto, l4proto, result, range))
+			return 1;
+	}
 
-	return in_range(l3proto, l4proto, result, range);
+	return 0;
 }
 
 /* For [FUTURE] fragmentation handling, we want the least-used
-- 
2.1.4

  parent reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-18 10:13 [PATCH 0/5] Netfilter fixes for net Pablo Neira Ayuso
2017-07-18 10:13 ` [PATCH 1/5] netfilter: nfnetlink: Improve input length sanitization in nfnetlink_rcv Pablo Neira Ayuso
2017-07-18 10:13 ` [PATCH 2/5] netfilter: remove old pre-netns era hook api Pablo Neira Ayuso
2017-07-18 10:13 ` Pablo Neira Ayuso [this message]
2017-07-18 10:13 ` [PATCH 4/5] netfilter: nf_tables: only allow in/output for arp packets Pablo Neira Ayuso
2017-07-18 10:13 ` [PATCH 5/5] netfilter: expect: fix crash when putting uninited expectation Pablo Neira Ayuso
2017-07-18 19:03 ` [PATCH 0/5] Netfilter fixes for net David Miller
2017-07-18 21:11   ` Florian Westphal
2017-07-18 21:54     ` David Miller

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