nf: xt_socket: export the fancy sock finder code

The socket matching function has some nifty logic to get the struct sock
from the skb or from the connection tracker.
We export this so other xt_* can use it, similarly to ho how
xt_socket uses nf_tproxy_get_sock.

Change-Id: I11c58f59087e7f7ae09e4abd4b937cd3370fa2fd
Signed-off-by: JP Abgrall <jpa@google.com>

1 files changed, 46 insertions, 23 deletions

diff --git a/net/netfilter/xt_socket.c b/net/netfilter/xt_socket.c
index 9ea482d08cf7..ee8c5f5dcceb 100644
--- a/net/netfilter/xt_socket.c
+++ b/net/netfilter/xt_socket.c
@@ -35,7 +35,7 @@
 #include <net/netfilter/nf_conntrack.h>
 #endif
 
-static void
+void
 xt_socket_put_sk(struct sock *sk)
 {
 	if (sk->sk_state == TCP_TIME_WAIT)
@@ -43,6 +43,7 @@ xt_socket_put_sk(struct sock *sk)
 	else
 		sock_put(sk);
 }
+EXPORT_SYMBOL(xt_socket_put_sk);
 
 static int
 extract_icmp4_fields(const struct sk_buff *skb,
@@ -101,9 +102,8 @@ extract_icmp4_fields(const struct sk_buff *skb,
 	return 0;
 }
 
-static bool
-socket_match(const struct sk_buff *skb, struct xt_action_param *par,
-	     const struct xt_socket_mtinfo1 *info)
+struct sock*
+xt_socket_get4_sk(const struct sk_buff *skb, struct xt_action_param *par)
 {
 	const struct iphdr *iph = ip_hdr(skb);
 	struct udphdr _hdr, *hp = NULL;
@@ -120,7 +120,7 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par,
 		hp = skb_header_pointer(skb, ip_hdrlen(skb),
 					sizeof(_hdr), &_hdr);
 		if (hp == NULL)
-			return false;
+			return NULL;
 
 		protocol = iph->protocol;
 		saddr = iph->saddr;
@@ -131,9 +131,9 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par,
 	} else if (iph->protocol == IPPROTO_ICMP) {
 		if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr,
 					&sport, &dport))
-			return false;
+			return NULL;
 	} else {
-		return false;
+		return NULL;
 	}
 
 #ifdef XT_SOCKET_HAVE_CONNTRACK
@@ -157,6 +157,23 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par,
 
 	sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), protocol,
 				   saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY);
+
+	pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n",
+		 protocol, &saddr, ntohs(sport),
+		 &daddr, ntohs(dport),
+		 &iph->daddr, hp ? ntohs(hp->dest) : 0, sk);
+
+	return sk;
+}
+EXPORT_SYMBOL(xt_socket_get4_sk);
+
+static bool
+socket_match(const struct sk_buff *skb, struct xt_action_param *par,
+	     const struct xt_socket_mtinfo1 *info)
+{
+	struct sock *sk;
+
+	sk = xt_socket_get4_sk(skb, par);
 	if (sk != NULL) {
 		bool wildcard;
 		bool transparent = true;
@@ -179,11 +196,6 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par,
 			sk = NULL;
 	}
 
-	pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n",
-		 protocol, &saddr, ntohs(sport),
-		 &daddr, ntohs(dport),
-		 &iph->daddr, hp ? ntohs(hp->dest) : 0, sk);
-
 	return (sk != NULL);
 }
 
@@ -255,8 +267,8 @@ extract_icmp6_fields(const struct sk_buff *skb,
 	return 0;
 }
 
-static bool
-socket_mt6_v1(const struct sk_buff *skb, struct xt_action_param *par)
+struct sock*
+xt_socket_get6_sk(const struct sk_buff *skb, struct xt_action_param *par)
 {
 	struct ipv6hdr *iph = ipv6_hdr(skb);
 	struct udphdr _hdr, *hp = NULL;
@@ -276,7 +288,7 @@ socket_mt6_v1(const struct sk_buff *skb, struct xt_action_param *par)
 		hp = skb_header_pointer(skb, thoff,
 					sizeof(_hdr), &_hdr);
 		if (hp == NULL)
-			return false;
+			return NULL;
 
 		saddr = &iph->saddr;
 		sport = hp->source;
@@ -286,13 +298,30 @@ socket_mt6_v1(const struct sk_buff *skb, struct xt_action_param *par)
 	} else if (tproto == IPPROTO_ICMPV6) {
 		if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr,
 					 &sport, &dport))
-			return false;
+			return NULL;
 	} else {
-		return false;
+		return NULL;
 	}
 
 	sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto,
 				   saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY);
+	pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu "
+		 "(orig %pI6:%hu) sock %p\n",
+		 tproto, saddr, ntohs(sport),
+		 daddr, ntohs(dport),
+		 &iph->daddr, hp ? ntohs(hp->dest) : 0, sk);
+	return sk;
+}
+EXPORT_SYMBOL(xt_socket_get6_sk);
+
+static bool
+socket_mt6_v1(const struct sk_buff *skb, struct xt_action_param *par)
+{
+	struct sock *sk;
+	const struct xt_socket_mtinfo1 *info;
+
+	info = (struct xt_socket_mtinfo1 *) par->matchinfo;
+	sk = xt_socket_get6_sk(skb, par);
 	if (sk != NULL) {
 		bool wildcard;
 		bool transparent = true;
@@ -315,12 +344,6 @@ socket_mt6_v1(const struct sk_buff *skb, struct xt_action_param *par)
 			sk = NULL;
 	}
 
-	pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu "
-		 "(orig %pI6:%hu) sock %p\n",
-		 tproto, saddr, ntohs(sport),
-		 daddr, ntohs(dport),
-		 &iph->daddr, hp ? ntohs(hp->dest) : 0, sk);
-
 	return (sk != NULL);
 }
 #endif