block: add a blk_plug_device_unlocked() that grabs the queue lock

[linux-2.6-omap-h63xx.git] / net / netfilter / xt_TCPMSS.c

diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c
index 60e3767cc71deb40f61e0d8ecaf9c87a76fc8996..beb5094703cb5e7c6d897bd34f0ccf4a4b86c7ce 100644 (file)
--- a/net/netfilter/xt_TCPMSS.c
+++ b/net/netfilter/xt_TCPMSS.c
@@ -13,7 +13,10 @@
 #include <linux/ip.h>
 #include <linux/ipv6.h>
 #include <linux/tcp.h>
+#include <net/dst.h>
+#include <net/flow.h>
 #include <net/ipv6.h>
+#include <net/route.h>
 #include <net/tcp.h>
 
 #include <linux/netfilter_ipv4/ip_tables.h>
@@ -41,6 +44,7 @@ optlen(const u_int8_t *opt, unsigned int offset)
 static int
 tcpmss_mangle_packet(struct sk_buff *skb,
                     const struct xt_tcpmss_info *info,
+                    unsigned int in_mtu,
                     unsigned int tcphoff,
                     unsigned int minlen)
 {
@@ -76,7 +80,13 @@ tcpmss_mangle_packet(struct sk_buff *skb,
                                       dst_mtu(skb->dst));
                        return -1;
                }
-               newmss = dst_mtu(skb->dst) - minlen;
+               if (in_mtu <= minlen) {
+                       if (net_ratelimit())
+                               printk(KERN_ERR "xt_TCPMSS: unknown or "
+                                      "invalid path-MTU (%u)\n", in_mtu);
+                       return -1;
+               }
+               newmss = min(dst_mtu(skb->dst), in_mtu) - minlen;
        } else
                newmss = info->mss;
 
@@ -137,6 +147,32 @@ tcpmss_mangle_packet(struct sk_buff *skb,
        return TCPOLEN_MSS;
 }
 
+static u_int32_t tcpmss_reverse_mtu(const struct sk_buff *skb,
+                                   unsigned int family)
+{
+       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(family);
+       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_tg4(struct sk_buff *skb, const struct net_device *in,
            const struct net_device *out, unsigned int hooknum,
@@ -146,7 +182,9 @@ tcpmss_tg4(struct sk_buff *skb, const struct net_device *in,
        __be16 newlen;
        int ret;
 
-       ret = tcpmss_mangle_packet(skb, targinfo, iph->ihl * 4,
+       ret = tcpmss_mangle_packet(skb, targinfo,
+                                  tcpmss_reverse_mtu(skb, PF_INET),
+                                  iph->ihl * 4,
                                   sizeof(*iph) + sizeof(struct tcphdr));
        if (ret < 0)
                return NF_DROP;
@@ -174,7 +212,9 @@ 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, tcphoff,
+       ret = tcpmss_mangle_packet(skb, targinfo,
+                                  tcpmss_reverse_mtu(skb, PF_INET6),
+                                  tcphoff,
                                   sizeof(*ipv6h) + sizeof(struct tcphdr));
        if (ret < 0)
                return NF_DROP;