netfilter: nf_nat_sip: add TCP support

Add support for mangling TCP SIP packets.

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

2 files changed, 57 insertions, 6 deletions

diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c
index b232e4040dc6..11b538deaaec 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 1cc75c5a822b..3bb3aaff76e9 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;
 }