ipvs: Add generic ensure_mtu_is_adequate to handle mixed pools

The out_rt functions check to see if the mtu is large enough for the packet
and, if not, send icmp messages (TOOBIG or DEST_UNREACH) to the source and
bail out.  We needed the ability to send ICMP from the out_rt_v6 function
and DEST_UNREACH from the out_rt function, so we just pulled it out into a
common function.

Signed-off-by: Alex Gartrell <agartrell@fb.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Simon Horman <horms@verge.net.au>

diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
index 034a282a6f8c4577d6301be9ea5dc549893fa51c..fa2fdd7421b7c84e30232b195414693f9af62fd4 100644 (file)
--- a/net/netfilter/ipvs/ip_vs_xmit.c
+++ b/net/netfilter/ipvs/ip_vs_xmit.c
@@ -213,17 +213,57 @@ static inline void maybe_update_pmtu(int skb_af, struct sk_buff *skb, int mtu)
                ort->dst.ops->update_pmtu(&ort->dst, sk, NULL, mtu);
 }
 
+static inline bool ensure_mtu_is_adequate(int skb_af, int rt_mode,
+                                         struct ip_vs_iphdr *ipvsh,
+                                         struct sk_buff *skb, int mtu)
+{
+#ifdef CONFIG_IP_VS_IPV6
+       if (skb_af == AF_INET6) {
+               struct net *net = dev_net(skb_dst(skb)->dev);
+
+               if (unlikely(__mtu_check_toobig_v6(skb, mtu))) {
+                       if (!skb->dev)
+                               skb->dev = net->loopback_dev;
+                       /* only send ICMP too big on first fragment */
+                       if (!ipvsh->fragoffs)
+                               icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
+                       IP_VS_DBG(1, "frag needed for %pI6c\n",
+                                 &ipv6_hdr(skb)->saddr);
+                       return false;
+               }
+       } else
+#endif
+       {
+               struct netns_ipvs *ipvs = net_ipvs(skb_net(skb));
+
+               /* If we're going to tunnel the packet and pmtu discovery
+                * is disabled, we'll just fragment it anyway
+                */
+               if ((rt_mode & IP_VS_RT_MODE_TUNNEL) && !sysctl_pmtu_disc(ipvs))
+                       return true;
+
+               if (unlikely(ip_hdr(skb)->frag_off & htons(IP_DF) &&
+                            skb->len > mtu && !skb_is_gso(skb))) {
+                       icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
+                                 htonl(mtu));
+                       IP_VS_DBG(1, "frag needed for %pI4\n",
+                                 &ip_hdr(skb)->saddr);
+                       return false;
+               }
+       }
+
+       return true;
+}
+
 /* Get route to destination or remote server */
 static int
 __ip_vs_get_out_rt(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest,
-                  __be32 daddr, int rt_mode, __be32 *ret_saddr)
+                  __be32 daddr, int rt_mode, __be32 *ret_saddr,
+                  struct ip_vs_iphdr *ipvsh)
 {
        struct net *net = dev_net(skb_dst(skb)->dev);
-       struct netns_ipvs *ipvs = net_ipvs(net);
        struct ip_vs_dest_dst *dest_dst;
        struct rtable *rt;                      /* Route to the other host */
-       struct iphdr *iph;
-       __be16 df;
        int mtu;
        int local, noref = 1;
 
@@ -279,7 +319,6 @@ __ip_vs_get_out_rt(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest,
                             " daddr=%pI4\n", &dest->addr.ip);
                goto err_put;
        }
-       iph = ip_hdr(skb);
 
        if (unlikely(local)) {
                /* skb to local stack, preserve old route */
@@ -290,7 +329,6 @@ __ip_vs_get_out_rt(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest,
 
        if (likely(!(rt_mode & IP_VS_RT_MODE_TUNNEL))) {
                mtu = dst_mtu(&rt->dst);
-               df = iph->frag_off & htons(IP_DF);
        } else {
                mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr);
                if (mtu < 68) {
@@ -298,16 +336,10 @@ __ip_vs_get_out_rt(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest,
                        goto err_put;
                }
                maybe_update_pmtu(skb_af, skb, mtu);
-               /* MTU check allowed? */
-               df = sysctl_pmtu_disc(ipvs) ? iph->frag_off & htons(IP_DF) : 0;
        }
 
-       /* MTU checking */
-       if (unlikely(df && skb->len > mtu && !skb_is_gso(skb))) {
-               icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
-               IP_VS_DBG(1, "frag needed for %pI4\n", &iph->saddr);
+       if (!ensure_mtu_is_adequate(skb_af, rt_mode, ipvsh, skb, mtu))
                goto err_put;
-       }
 
        skb_dst_drop(skb);
        if (noref) {
@@ -450,15 +482,8 @@ __ip_vs_get_out_rt_v6(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest,
                maybe_update_pmtu(skb_af, skb, mtu);
        }
 
-       if (unlikely(__mtu_check_toobig_v6(skb, mtu))) {
-               if (!skb->dev)
-                       skb->dev = net->loopback_dev;
-               /* only send ICMP too big on first fragment */
-               if (!ipvsh->fragoffs)
-                       icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
-               IP_VS_DBG(1, "frag needed for %pI6c\n", &ipv6_hdr(skb)->saddr);
+       if (!ensure_mtu_is_adequate(skb_af, rt_mode, ipvsh, skb, mtu))
                goto err_put;
-       }
 
        skb_dst_drop(skb);
        if (noref) {
@@ -565,7 +590,7 @@ ip_vs_bypass_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
 
        rcu_read_lock();
        if (__ip_vs_get_out_rt(cp->af, skb, NULL, iph->daddr,
-                              IP_VS_RT_MODE_NON_LOCAL, NULL) < 0)
+                              IP_VS_RT_MODE_NON_LOCAL, NULL, ipvsh) < 0)
                goto tx_error;
 
        ip_send_check(iph);
@@ -644,7 +669,7 @@ ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
        local = __ip_vs_get_out_rt(cp->af, skb, cp->dest, cp->daddr.ip,
                                   IP_VS_RT_MODE_LOCAL |
                                   IP_VS_RT_MODE_NON_LOCAL |
-                                  IP_VS_RT_MODE_RDR, NULL);
+                                  IP_VS_RT_MODE_RDR, NULL, ipvsh);
        if (local < 0)
                goto tx_error;
        rt = skb_rtable(skb);
@@ -841,7 +866,7 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
                                   IP_VS_RT_MODE_LOCAL |
                                   IP_VS_RT_MODE_NON_LOCAL |
                                   IP_VS_RT_MODE_CONNECT |
-                                  IP_VS_RT_MODE_TUNNEL, &saddr);
+                                  IP_VS_RT_MODE_TUNNEL, &saddr, ipvsh);
        if (local < 0)
                goto tx_error;
        if (local) {
@@ -1032,7 +1057,7 @@ ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
        local = __ip_vs_get_out_rt(cp->af, skb, cp->dest, cp->daddr.ip,
                                   IP_VS_RT_MODE_LOCAL |
                                   IP_VS_RT_MODE_NON_LOCAL |
-                                  IP_VS_RT_MODE_KNOWN_NH, NULL);
+                                  IP_VS_RT_MODE_KNOWN_NH, NULL, ipvsh);
        if (local < 0)
                goto tx_error;
        if (local) {
@@ -1137,7 +1162,7 @@ ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
                  IP_VS_RT_MODE_RDR : IP_VS_RT_MODE_NON_LOCAL;
        rcu_read_lock();
        local = __ip_vs_get_out_rt(cp->af, skb, cp->dest, cp->daddr.ip, rt_mode,
-                                  NULL);
+                                  NULL, iph);
        if (local < 0)
                goto tx_error;
        rt = skb_rtable(skb);