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Subject[patch 12/23] [PATCH] [NETFILTER] PPTP helper: fix PNS-PAC expectation call id
-stable review patch.  If anyone has any objections, please let us know.
------------------

The reply tuple of the PNS->PAC expectation was using the wrong call id.

So we had the following situation:
- PNS behind NAT firewall
- PNS call id requires NATing
- PNS->PAC gre packet arrives first

then the PNS->PAC expectation is matched, and the other expectation
is deleted, but the PAC->PNS gre packets do not match the gre conntrack
because the call id is wrong.

We also cannot use ip_nat_follow_master().

Signed-off-by: Philip Craig <philipc@snapgear.com>
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
net/ipv4/netfilter/ip_nat_helper_pptp.c | 28 ++++++++++++++++++++++++++--
1 file changed, 26 insertions(+), 2 deletions(-)

--- linux-2.6.14.2.orig/net/ipv4/netfilter/ip_nat_helper_pptp.c
+++ linux-2.6.14.2/net/ipv4/netfilter/ip_nat_helper_pptp.c
@@ -73,6 +73,7 @@ static void pptp_nat_expected(struct ip_
struct ip_conntrack_tuple t;
struct ip_ct_pptp_master *ct_pptp_info;
struct ip_nat_pptp *nat_pptp_info;
+ struct ip_nat_range range;

ct_pptp_info = &master->help.ct_pptp_info;
nat_pptp_info = &master->nat.help.nat_pptp_info;
@@ -110,7 +111,30 @@ static void pptp_nat_expected(struct ip_
DEBUGP("not found!\n");
}

- ip_nat_follow_master(ct, exp);
+ /* This must be a fresh one. */
+ BUG_ON(ct->status & IPS_NAT_DONE_MASK);
+
+ /* Change src to where master sends to */
+ range.flags = IP_NAT_RANGE_MAP_IPS;
+ range.min_ip = range.max_ip
+ = ct->master->tuplehash[!exp->dir].tuple.dst.ip;
+ if (exp->dir == IP_CT_DIR_ORIGINAL) {
+ range.flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
+ range.min = range.max = exp->saved_proto;
+ }
+ /* hook doesn't matter, but it has to do source manip */
+ ip_nat_setup_info(ct, &range, NF_IP_POST_ROUTING);
+
+ /* For DST manip, map port here to where it's expected. */
+ range.flags = IP_NAT_RANGE_MAP_IPS;
+ range.min_ip = range.max_ip
+ = ct->master->tuplehash[!exp->dir].tuple.src.ip;
+ if (exp->dir == IP_CT_DIR_REPLY) {
+ range.flags |= IP_NAT_RANGE_PROTO_SPECIFIED;
+ range.min = range.max = exp->saved_proto;
+ }
+ /* hook doesn't matter, but it has to do destination manip */
+ ip_nat_setup_info(ct, &range, NF_IP_PRE_ROUTING);
}

/* outbound packets == from PNS to PAC */
@@ -213,7 +237,7 @@ pptp_exp_gre(struct ip_conntrack_expect

/* alter expectation for PNS->PAC direction */
invert_tuplepr(&inv_t, &expect_orig->tuple);
- expect_orig->saved_proto.gre.key = htons(nat_pptp_info->pac_call_id);
+ expect_orig->saved_proto.gre.key = htons(ct_pptp_info->pns_call_id);
expect_orig->tuple.src.u.gre.key = htons(nat_pptp_info->pns_call_id);
expect_orig->tuple.dst.u.gre.key = htons(ct_pptp_info->pac_call_id);
inv_t.src.ip = reply_t->src.ip;
--
-
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