From c5807ace66d5085ed94608a7e9a084085ea57ede Mon Sep 17 00:00:00 2001 From: Jorge Boncompte Date: Fri, 4 May 2007 01:00:32 +0200 Subject: [NETFILTER]: ip_nat_proto_gre: do not modify/corrupt GREv0 packets through NAT While porting some changes of the 2.6.21-rc7 pptp/proto_gre conntrack and nat modules to a 2.4.32 kernel I noticed that the gre_key function returns a wrong pointer to the GRE key of a version 0 packet thus corrupting the packet payload. The intended behaviour for GREv0 packets is to act like ip_conntrack_proto_generic/ip_nat_proto_unknown so I have ripped the offending functions (not used anymore) and modified the ip_nat_proto_gre modules to not touch version 0 (non PPTP) packets. Signed-off-by: Jorge Boncompte Signed-off-by: Patrick McHardy Signed-off-by: Adrian Bunk --- net/ipv4/netfilter/ip_nat_proto_gre.c | 21 ++++++++------------- 1 file changed, 8 insertions(+), 13 deletions(-) (limited to 'net') diff --git a/net/ipv4/netfilter/ip_nat_proto_gre.c b/net/ipv4/netfilter/ip_nat_proto_gre.c index 6c4899d8046a..fb4ec670f005 100644 --- a/net/ipv4/netfilter/ip_nat_proto_gre.c +++ b/net/ipv4/netfilter/ip_nat_proto_gre.c @@ -71,6 +71,11 @@ gre_unique_tuple(struct ip_conntrack_tuple *tuple, u_int16_t *keyptr; unsigned int min, i, range_size; + /* If there is no master conntrack we are not PPTP, + do not change tuples */ + if (!conntrack->master) + return 0; + if (maniptype == IP_NAT_MANIP_SRC) keyptr = &tuple->src.u.gre.key; else @@ -123,19 +128,9 @@ gre_manip_pkt(struct sk_buff **pskb, if (maniptype == IP_NAT_MANIP_DST) { /* key manipulation is always dest */ switch (greh->version) { - case 0: - if (!greh->key) { - DEBUGP("can't nat GRE w/o key\n"); - break; - } - if (greh->csum) { - /* FIXME: Never tested this code... */ - *(gre_csum(greh)) = - ip_nat_cheat_check(~*(gre_key(greh)), - tuple->dst.u.gre.key, - *(gre_csum(greh))); - } - *(gre_key(greh)) = tuple->dst.u.gre.key; + case GRE_VERSION_1701: + /* We do not currently NAT any GREv0 packets. + * Try to behave like "ip_nat_proto_unknown" */ break; case GRE_VERSION_PPTP: DEBUGP("call_id -> 0x%04x\n", -- cgit v1.2.3