netfilter -stable 01/04: nf_nat: fix inverted logic for persistent NAT mappings

Patrick McHardy
2009-09-17T11:58:26Z

commit c9aa9e5a37216258a9d18e42e764f423c818ad4f
Author: Patrick McHardy <kaber@trash.net>
Date: Thu Sep 17 13:27:42 2009 +0200

netfilter: nf_nat: fix inverted logic for persistent NAT mappings

Upstream commit cce5a5c3:

Kernel 2.6.30 introduced a patch [1] for the persistent option in the
netfilter SNAT target. This is exactly what we need here so I had a quick look
at the code and noticed that the patch is wrong. The logic is simply inverted.
The patch below fixes this.

Also note that because of this the default behavior of the SNAT target has
changed since kernel 2.6.30 as it now ignores the destination IP in choosing
the source IP for nating (which should only be the case if the persistent
option is set).

[1] http://git.eu.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=98d500d66cb7940747b424b245fc6a51ecfbf005

Signed-off-by: Maximilian Engelhardt <maxi@daemonizer.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/net/ipv4/netfilter/nf_nat_core.c b/net/ipv4/netfilter/nf_nat_core.c
index 3229e0a..b6ddd56 100644
--- a/net/ipv4/netfilter/nf_nat_core.c
+++ b/net/ipv4/netfilter/nf_nat_core.c
@@ -212,7 +212,7 @@ find_best_ips_proto(struct nf_conntrack_tuple *tuple,
maxip = ntohl(range->max_ip);
j = jhash_2words((__force u32)tuple->src.u3.ip,
range->flags & IP_NAT_RANGE_PERSISTENT ?
- (__force u32)tuple->dst.u3.ip : 0, 0);
+ 0 : (__force u32)tuple->dst.u3.ip, 0);
j = ((u64)j * (maxip - minip + 1)) >> 32;
*var_ipp = htonl(minip + j);
}