Patch "netfilter: nat: fix src map lookup" has been added to the 4.12-stable tree

Patch "netfilter: nat: fix src map lookup" has been added to the 4.12-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    netfilter: nat: fix src map lookup

to the 4.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     netfilter-nat-fix-src-map-lookup.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 97772bcd56efa21d9d8976db6f205574ea602f51 Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Fri, 7 Jul 2017 13:07:17 +0200
Subject: netfilter: nat: fix src map lookup

From: Florian Westphal <fw@strlen.de>

commit 97772bcd56efa21d9d8976db6f205574ea602f51 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/netfilter/nf_nat_core.c |   17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

--- 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


Patches currently in stable-queue which might be from fw@strlen.de are

queue-4.12/netfilter-nfnetlink-improve-input-length-sanitization-in-nfnetlink_rcv.patch
queue-4.12/netfilter-expect-fix-crash-when-putting-uninited-expectation.patch
queue-4.12/netfilter-nat-fix-src-map-lookup.patch