From: Patrick McHardy Subject: [NETFILTER 02/04]: nf_nat_proto_gre: do not modify/corrupt GREv0 packets through NAT Date: Thu, 3 May 2007 03:25:59 +0200 (MEST) Message-ID: <20070503012440.12818.75627.sendpatchset@localhost.localdomain> References: <20070503012437.12818.39126.sendpatchset@localhost.localdomain> Cc: netfilter-devel@lists.netfilter.org, Patrick McHardy To: davem@davemloft.net Return-path: In-Reply-To: <20070503012437.12818.39126.sendpatchset@localhost.localdomain> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: netfilter-devel-bounces@lists.netfilter.org Errors-To: netfilter-devel-bounces@lists.netfilter.org List-Id: netfilter-devel.vger.kernel.org [NETFILTER]: nf_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 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 Signed-off-by: Patrick McHardy --- commit 08130cb0faa275f6a8290a39942e58c18cec3533 tree 01dab60a8b7759c68701292b636000bc063492d3 parent 316258f1e782f387bcd01fd81d673aaeec24b8dc author Jorge Boncompte Wed, 02 May 2007 16:17:31 +0200 committer Patrick McHardy Thu, 03 May 2007 02:51:46 +0200 include/linux/netfilter/nf_conntrack_proto_gre.h | 18 ------------------ net/ipv4/netfilter/nf_nat_proto_gre.c | 20 ++++++++------------ 2 files changed, 8 insertions(+), 30 deletions(-) diff --git a/include/linux/netfilter/nf_conntrack_proto_gre.h b/include/linux/netfilter/nf_conntrack_proto_gre.h index 4e6bbce..535e421 100644 --- a/include/linux/netfilter/nf_conntrack_proto_gre.h +++ b/include/linux/netfilter/nf_conntrack_proto_gre.h @@ -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); diff --git a/net/ipv4/netfilter/nf_nat_proto_gre.c b/net/ipv4/netfilter/nf_nat_proto_gre.c index e5a34c1..af8ba79 100644 --- a/net/ipv4/netfilter/nf_nat_proto_gre.c +++ b/net/ipv4/netfilter/nf_nat_proto_gre.c @@ -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));