netfilter: xt_TCPMSS: collapse tcpmss_reverse_mtu{4,6} into one function

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 13 insertions, 29 deletions

diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c
index 217e2b68632..beb5094703c 100644
--- a/net/netfilter/xt_TCPMSS.c
+++ b/net/netfilter/xt_TCPMSS.c
@@ -147,17 +147,21 @@ tcpmss_mangle_packet(struct sk_buff *skb,
         return TCPOLEN_MSS;
 }
 
-static u_int32_t tcpmss_reverse_mtu4(const struct iphdr *iph)
+static u_int32_t tcpmss_reverse_mtu(const struct sk_buff *skb,
+                                    unsigned int family)
 {
-        struct flowi fl = {
-                .fl4_dst = iph->saddr,
-        };
+        struct flowi fl = {};
         const struct nf_afinfo *ai;
         struct rtable *rt = NULL;
         u_int32_t mtu     = ~0U;
 
+        if (family == PF_INET)
+                fl.fl4_dst = ip_hdr(skb)->saddr;
+        else
+                fl.fl6_dst = ipv6_hdr(skb)->saddr;
+
         rcu_read_lock();
-        ai = nf_get_afinfo(AF_INET);
+        ai = nf_get_afinfo(family);
         if (ai != NULL)
                 ai->route((struct dst_entry **)&rt, &fl);
         rcu_read_unlock();
@@ -178,7 +182,8 @@ tcpmss_tg4(struct sk_buff *skb, const struct net_device *in,
         __be16 newlen;
         int ret;
 
-        ret = tcpmss_mangle_packet(skb, targinfo, tcpmss_reverse_mtu4(iph),
+        ret = tcpmss_mangle_packet(skb, targinfo,
+                                   tcpmss_reverse_mtu(skb, PF_INET),
                                    iph->ihl * 4,
                                    sizeof(*iph) + sizeof(struct tcphdr));
         if (ret < 0)
@@ -193,28 +198,6 @@ tcpmss_tg4(struct sk_buff *skb, const struct net_device *in,
 }
 
 #if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE)
-static u_int32_t tcpmss_reverse_mtu6(const struct ipv6hdr *iph)
-{
-        struct flowi fl = {
-                .fl6_dst = iph->saddr,
-        };
-        const struct nf_afinfo *ai;
-        struct rtable *rt = NULL;
-        u_int32_t mtu     = ~0U;
-
-        rcu_read_lock();
-        ai = nf_get_afinfo(AF_INET6);
-        if (ai != NULL)
-                ai->route((struct dst_entry **)&rt, &fl);
-        rcu_read_unlock();
-
-        if (rt != NULL) {
-                mtu = dst_mtu(&rt->u.dst);
-                dst_release(&rt->u.dst);
-        }
-        return mtu;
-}
-
 static unsigned int
 tcpmss_tg6(struct sk_buff *skb, const struct net_device *in,
            const struct net_device *out, unsigned int hooknum,
@@ -229,7 +212,8 @@ tcpmss_tg6(struct sk_buff *skb, const struct net_device *in,
         tcphoff = ipv6_skip_exthdr(skb, sizeof(*ipv6h), &nexthdr);
         if (tcphoff < 0)
                 return NF_DROP;
-        ret = tcpmss_mangle_packet(skb, targinfo, tcpmss_reverse_mtu6(ipv6h),
+        ret = tcpmss_mangle_packet(skb, targinfo,
+                                   tcpmss_reverse_mtu(skb, PF_INET6),
                                    tcphoff,
                                    sizeof(*ipv6h) + sizeof(struct tcphdr));
         if (ret < 0)