netfilter 45/62: nf_nat_sip: add TCP support

Patrick McHardy
2010-02-16T14:56:21Z

commit 48f8ac26537c1b7b1a2422f5232f45d06c945348
Author: Patrick McHardy <kaber@trash.net>
Date: Thu Feb 11 12:29:38 2010 +0100

netfilter: nf_nat_sip: add TCP support

Add support for mangling TCP SIP packets.

Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/include/linux/netfilter/nf_conntrack_sip.h b/include/linux/netfilter/nf_conntrack_sip.h
index fa9bb89..cd84d6f 100644
--- a/include/linux/netfilter/nf_conntrack_sip.h
+++ b/include/linux/netfilter/nf_conntrack_sip.h
@@ -104,6 +104,7 @@ extern unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb,
unsigned int dataoff,
const char **dptr,
unsigned int *datalen);
+extern void (*nf_nat_sip_seq_adjust_hook)(struct sk_buff *skb, s16 off);
extern unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb,
unsigned int dataoff,
const char **dptr,
diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c
index b232e40..11b538d 100644
--- a/net/ipv4/netfilter/nf_nat_sip.c
+++ b/net/ipv4/netfilter/nf_nat_sip.c
@@ -1,4 +1,4 @@
-/* SIP extension for UDP NAT alteration.
+/* SIP extension for NAT alteration.
*
* (C) 2005 by Christian Hentschel <chentschel@arnet.com.ar>
* based on RR's ip_nat_ftp.c and other modules.
@@ -15,6 +15,7 @@
#include <linux/ip.h>
#include <net/ip.h>
#include <linux/udp.h>
+#include <linux/tcp.h>

#include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_helper.h>
@@ -36,10 +37,27 @@ static unsigned int mangle_packet(struct sk_buff *skb, unsigned int dataoff,
{
enum ip_conntrack_info ctinfo;
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-
- if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, matchoff, matchlen,
- buffer, buflen))
- return 0;
+ struct tcphdr *th;
+ unsigned int baseoff;
+
+ if (nf_ct_protonum(ct) == IPPROTO_TCP) {
+ th = (struct tcphdr *)(skb->data + ip_hdrlen(skb));
+ baseoff = ip_hdrlen(skb) + th->doff * 4;
+ matchoff += dataoff - baseoff;
+
+ if (!__nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
+ matchoff, matchlen,
+ buffer, buflen, false))
+ return 0;
+ } else {
+ baseoff = ip_hdrlen(skb) + sizeof(struct udphdr);
+ matchoff += dataoff - baseoff;
+
+ if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo,
+ matchoff, matchlen,
+ buffer, buflen))
+ return 0;
+ }

/* Reload data pointer and adjust datalen value */
*dptr = skb->data + dataoff;
@@ -104,6 +122,7 @@ static unsigned int ip_nat_sip(struct sk_buff *skb, unsigned int dataoff,
struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
unsigned int coff, matchoff, matchlen;
+ enum sip_header_types hdr;
union nf_inet_addr addr;
__be16 port;
int request, in_header;
@@ -120,9 +139,14 @@ static unsigned int ip_nat_sip(struct sk_buff *skb, unsigned int dataoff,
} else
request = 0;

+ if (nf_ct_protonum(ct) == IPPROTO_TCP)
+ hdr = SIP_HDR_VIA_TCP;
+ else
+ hdr = SIP_HDR_VIA_UDP;
+
/* Translate topmost Via header and parameters */
if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
- SIP_HDR_VIA_UDP, NULL, &matchoff, &matchlen,
+ hdr, NULL, &matchoff, &matchlen,
&addr, &port) > 0) {
unsigned int matchend, poff, plen, buflen, n;
char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
@@ -204,9 +228,23 @@ next:
if (!map_sip_addr(skb, dataoff, dptr, datalen, SIP_HDR_FROM) ||
!map_sip_addr(skb, dataoff, dptr, datalen, SIP_HDR_TO))
return NF_DROP;
+
return NF_ACCEPT;
}

+static void ip_nat_sip_seq_adjust(struct sk_buff *skb, s16 off)
+{
+ enum ip_conntrack_info ctinfo;
+ struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+ const struct tcphdr *th;
+
+ if (nf_ct_protonum(ct) != IPPROTO_TCP || off == 0)
+ return;
+
+ th = (struct tcphdr *)(skb->data + ip_hdrlen(skb));
+ nf_nat_set_seq_adjust(ct, ctinfo, th->seq, off);
+}
+
/* Handles expected signalling connections and media streams */
static void ip_nat_sip_expected(struct nf_conn *ct,
struct nf_conntrack_expect *exp)
@@ -472,6 +510,7 @@ err1:
static void __exit nf_nat_sip_fini(void)
{
rcu_assign_pointer(nf_nat_sip_hook, NULL);
+ rcu_assign_pointer(nf_nat_sip_seq_adjust_hook, NULL);
rcu_assign_pointer(nf_nat_sip_expect_hook, NULL);
rcu_assign_pointer(nf_nat_sdp_addr_hook, NULL);
rcu_assign_pointer(nf_nat_sdp_port_hook, NULL);
@@ -483,12 +522,14 @@ static void __exit nf_nat_sip_fini(void)
static int __init nf_nat_sip_init(void)
{
BUG_ON(nf_nat_sip_hook != NULL);
+ BUG_ON(nf_nat_sip_seq_adjust_hook != NULL);
BUG_ON(nf_nat_sip_expect_hook != NULL);
BUG_ON(nf_nat_sdp_addr_hook != NULL);
BUG_ON(nf_nat_sdp_port_hook != NULL);
BUG_ON(nf_nat_sdp_session_hook != NULL);
BUG_ON(nf_nat_sdp_media_hook != NULL);
rcu_assign_pointer(nf_nat_sip_hook, ip_nat_sip);
+ rcu_assign_pointer(nf_nat_sip_seq_adjust_hook, ip_nat_sip_seq_adjust);
rcu_assign_pointer(nf_nat_sip_expect_hook, ip_nat_sip_expect);
rcu_assign_pointer(nf_nat_sdp_addr_hook, ip_nat_sdp_addr);
rcu_assign_pointer(nf_nat_sdp_port_hook, ip_nat_sdp_port);
diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index 1cc75c5..3bb3aaf 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -56,6 +56,9 @@ unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb, unsigned int dataoff,
unsigned int *datalen) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_sip_hook);

+void (*nf_nat_sip_seq_adjust_hook)(struct sk_buff *skb, s16 off) __read_mostly;
+EXPORT_SYMBOL_GPL(nf_nat_sip_seq_adjust_hook);
+
unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb,
unsigned int dataoff,
const char **dptr,
@@ -1360,6 +1363,7 @@ static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
const char *dptr, *end;
s16 diff, tdiff = 0;
int ret;
+ typeof(nf_nat_sip_seq_adjust_hook) nf_nat_sip_seq_adjust;

if (ctinfo != IP_CT_ESTABLISHED &&
ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY)
@@ -1415,6 +1419,12 @@ static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
datalen = datalen + diff - msglen;
}

+ if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
+ nf_nat_sip_seq_adjust = rcu_dereference(nf_nat_sip_seq_adjust_hook);
+ if (nf_nat_sip_seq_adjust)
+ nf_nat_sip_seq_adjust(skb, tdiff);
+ }
+
return ret;
}