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[NETFILTER]: nf_nat_proto_gre: do not modify/corrupt GREv0 packets through NAT

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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
nf_conntrack_proto_generic/nf_nat_proto_unknown so I have ripped the
offending functions (not used anymore) and modified the
nf_nat_proto_gre modules to not touch version 0 (non PPTP) packets.

Signed-off-by: Jorge Boncompte <jorge@dti2.net>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jorge Boncompte 2007-05-03 03:34:42 -07:00 committed by David S. Miller
parent 327850070b
commit c2a1910b06
2 changed files with 8 additions and 30 deletions
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18
include/linux/netfilter/nf_conntrack_proto_gre.h
View File

@ -87,24 +87,6 @@ int nf_ct_gre_keymap_add(struct nf_conn *ct, enum ip_conntrack_dir dir,
/* delete keymap entries */
void nf_ct_gre_keymap_destroy(struct nf_conn *ct);
/* get pointer to gre key, if present */
static inline __be32 *gre_key(struct gre_hdr *greh)
{
if (!greh->key)
return NULL;
if (greh->csum || greh->routing)
return (__be32 *)(greh+sizeof(*greh)+4);
return (__be32 *)(greh+sizeof(*greh));
}
/* get pointer ot gre csum, if present */
static inline __sum16 *gre_csum(struct gre_hdr *greh)
{
if (!greh->csum)
return NULL;
return (__sum16 *)(greh+sizeof(*greh));
}
extern void nf_ct_gre_keymap_flush(void);
extern void nf_nat_need_gre(void);

20
net/ipv4/netfilter/nf_nat_proto_gre.c
View File

@ -72,6 +72,11 @@ gre_unique_tuple(struct nf_conntrack_tuple *tuple,
__be16 *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
@ -122,18 +127,9 @@ gre_manip_pkt(struct sk_buff **pskb, unsigned int iphdroff,
if (maniptype != IP_NAT_MANIP_DST)
return 1;
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... */
nf_proto_csum_replace4(gre_csum(greh), *pskb,
*(gre_key(greh)),
tuple->dst.u.gre.key, 0);
}
*(gre_key(greh)) = tuple->dst.u.gre.key;
case GRE_VERSION_1701:
/* We do not currently NAT any GREv0 packets.
* Try to behave like "nf_nat_proto_unknown" */
break;
case GRE_VERSION_PPTP:
DEBUGP("call_id -> 0x%04x\n", ntohs(tuple->dst.u.gre.key));