netfilter: fix module dependency issues with IPv6 defragmentation, ip6tables and xt_TPROXY

One of the previous tproxy related patches split IPv6 defragmentation and
connection tracking, but did not correctly add Kconfig stanzas to handle the
new dependencies correctly. This patch fixes that by making the config options
mirror the setup we have for IPv4: a distinct config option for defragmentation
that is automatically selected by both connection tracking and
xt_TPROXY/xt_socket.

The patch also changes the #ifdefs enclosing IPv6 specific code in xt_socket
and xt_TPROXY: we only compile these in case we have ip6tables support enabled.
Signed-off-by: KOVACS Krisztian <hidden@balabit.hu>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/netfilter/Kconfig

@@ -5,10 +5,15 @@
 menu "IPv6: Netfilter Configuration"
 	depends on INET && IPV6 && NETFILTER
 
+config NF_DEFRAG_IPV6
+	tristate
+	default n
+
 config NF_CONNTRACK_IPV6
 	tristate "IPv6 connection tracking support"
 	depends on INET && IPV6 && NF_CONNTRACK
 	default m if NETFILTER_ADVANCED=n
+	select NF_DEFRAG_IPV6
 	---help---
 	  Connection tracking keeps a record of what packets have passed
 	  through your machine, in order to figure out how they are related

net/ipv6/netfilter/Makefile

@@ -12,11 +12,14 @@ obj-$(CONFIG_IP6_NF_SECURITY) += ip6table_security.o
 
 # objects for l3 independent conntrack
 nf_conntrack_ipv6-objs  :=  nf_conntrack_l3proto_ipv6.o nf_conntrack_proto_icmpv6.o
-nf_defrag_ipv6-objs := nf_defrag_ipv6_hooks.o nf_conntrack_reasm.o
 
 # l3 independent conntrack
 obj-$(CONFIG_NF_CONNTRACK_IPV6) += nf_conntrack_ipv6.o nf_defrag_ipv6.o
 
+# defrag
+nf_defrag_ipv6-objs := nf_defrag_ipv6_hooks.o nf_conntrack_reasm.o
+obj-$(CONFIG_NF_DEFRAG_IPV6) += nf_defrag_ipv6.o
+
 # matches
 obj-$(CONFIG_IP6_NF_MATCH_AH) += ip6t_ah.o
 obj-$(CONFIG_IP6_NF_MATCH_EUI64) += ip6t_eui64.o

net/netfilter/Kconfig

@@ -525,6 +525,7 @@ config NETFILTER_XT_TARGET_TPROXY
 	depends on NETFILTER_XTABLES
 	depends on NETFILTER_ADVANCED
 	select NF_DEFRAG_IPV4
+	select NF_DEFRAG_IPV6 if IP6_NF_IPTABLES
 	help
 	  This option adds a `TPROXY' target, which is somewhat similar to
 	  REDIRECT.  It can only be used in the mangle table and is useful
@@ -927,6 +928,7 @@ config NETFILTER_XT_MATCH_SOCKET
 	depends on NETFILTER_ADVANCED
 	depends on !NF_CONNTRACK || NF_CONNTRACK
 	select NF_DEFRAG_IPV4
+	select NF_DEFRAG_IPV6 if IP6_NF_IPTABLES
 	help
 	  This option adds a `socket' match, which can be used to match
 	  packets for which a TCP or UDP socket lookup finds a valid socket.

net/netfilter/xt_TPROXY.c

@@ -21,7 +21,9 @@
 #include <linux/netfilter_ipv4/ip_tables.h>
 
 #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
-#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+
+#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
+#define XT_TPROXY_HAVE_IPV6 1
 #include <net/if_inet6.h>
 #include <net/addrconf.h>
 #include <linux/netfilter_ipv6/ip6_tables.h>
@@ -172,7 +174,7 @@ tproxy_tg4_v1(struct sk_buff *skb, const struct xt_action_param *par)
 	return tproxy_tg4(skb, tgi->laddr.ip, tgi->lport, tgi->mark_mask, tgi->mark_value);
 }
 
-#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+#ifdef XT_TPROXY_HAVE_IPV6
 
 static inline const struct in6_addr *
 tproxy_laddr6(struct sk_buff *skb, const struct in6_addr *user_laddr,
@@ -372,7 +374,7 @@ static struct xt_target tproxy_tg_reg[] __read_mostly = {
 		.hooks		= 1 << NF_INET_PRE_ROUTING,
 		.me		= THIS_MODULE,
 	},
-#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+#ifdef XT_TPROXY_HAVE_IPV6
 	{
 		.name		= "TPROXY",
 		.family		= NFPROTO_IPV6,
@@ -391,7 +393,7 @@ static struct xt_target tproxy_tg_reg[] __read_mostly = {
 static int __init tproxy_tg_init(void)
 {
 	nf_defrag_ipv4_enable();
-#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+#ifdef XT_TPROXY_HAVE_IPV6
 	nf_defrag_ipv6_enable();
 #endif
 

net/netfilter/xt_socket.c

@@ -14,7 +14,6 @@
 #include <linux/skbuff.h>
 #include <linux/netfilter/x_tables.h>
 #include <linux/netfilter_ipv4/ip_tables.h>
-#include <linux/netfilter_ipv6/ip6_tables.h>
 #include <net/tcp.h>
 #include <net/udp.h>
 #include <net/icmp.h>
@@ -22,7 +21,12 @@
 #include <net/inet_sock.h>
 #include <net/netfilter/nf_tproxy_core.h>
 #include <net/netfilter/ipv4/nf_defrag_ipv4.h>
+
+#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
+#define XT_SOCKET_HAVE_IPV6 1
+#include <linux/netfilter_ipv6/ip6_tables.h>
 #include <net/netfilter/ipv6/nf_defrag_ipv6.h>
+#endif
 
 #include <linux/netfilter/xt_socket.h>
 
@@ -186,7 +190,7 @@ socket_mt4_v1(const struct sk_buff *skb, struct xt_action_param *par)
 	return socket_match(skb, par, par->matchinfo);
 }
 
-#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+#ifdef XT_SOCKET_HAVE_IPV6
 
 static int
 extract_icmp6_fields(const struct sk_buff *skb,
@@ -331,7 +335,7 @@ static struct xt_match socket_mt_reg[] __read_mostly = {
 				  (1 << NF_INET_LOCAL_IN),
 		.me		= THIS_MODULE,
 	},
-#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+#ifdef XT_SOCKET_HAVE_IPV6
 	{
 		.name		= "socket",
 		.revision	= 1,
@@ -348,7 +352,7 @@ static struct xt_match socket_mt_reg[] __read_mostly = {
 static int __init socket_mt_init(void)
 {
 	nf_defrag_ipv4_enable();
-#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
+#ifdef XT_SOCKET_HAVE_IPV6
 	nf_defrag_ipv6_enable();
 #endif