11 files changed, 72 insertions, 13 deletions

diff --git a/include/net/route.h b/include/net/route.h
index a36ae429ed5d..47eb25ac1f7f 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -215,7 +215,10 @@ static inline int ip_route_input_noref(struct sk_buff *skb, __be32 dst, __be32 s
         return ip_route_input_common(skb, dst, src, tos, devin, true);
 }
 
-extern void             ip_rt_send_redirect(struct sk_buff *skb);
+extern void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
+                             int oif, u32 mark, u8 protocol, int flow_flags);
+extern void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu);
+extern void ip_rt_send_redirect(struct sk_buff *skb);
 
 extern unsigned int             inet_addr_type(struct net *net, __be32 addr);
 extern unsigned int             inet_dev_addr_type(struct net *net, const struct net_device *dev, __be32 addr);
diff --git a/net/ipv4/ah4.c b/net/ipv4/ah4.c
index e8f2617ecd47..916d5ecaf6c6 100644
--- a/net/ipv4/ah4.c
+++ b/net/ipv4/ah4.c
@@ -408,6 +408,7 @@ static void ah4_err(struct sk_buff *skb, u32 info)
                 return;
         pr_debug("pmtu discovery on SA AH/%08x/%08x\n",
                  ntohl(ah->spi), ntohl(iph->daddr));
+        ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_AH, 0);
         xfrm_state_put(x);
 }
 
diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index cb982a61536f..7b95b49a36ce 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -494,6 +494,7 @@ static void esp4_err(struct sk_buff *skb, u32 info)
                 return;
         NETDEBUG(KERN_DEBUG "pmtu discovery on SA ESP/%08x/%08x\n",
                  ntohl(esph->spi), ntohl(iph->daddr));
+        ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_ESP, 0);
         xfrm_state_put(x);
 }
 
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index f49047b79609..594cec35ac4d 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -516,9 +516,6 @@ static void ipgre_err(struct sk_buff *skb, u32 info)
                 case ICMP_PORT_UNREACH:
                         /* Impossible event. */
                         return;
-                case ICMP_FRAG_NEEDED:
-                        /* Soft state for pmtu is maintained by IP core. */
-                        return;
                 default:
                         /* All others are translated to HOST_UNREACH.
                            rfc2003 contains "deep thoughts" about NET_UNREACH,
@@ -538,7 +535,16 @@ static void ipgre_err(struct sk_buff *skb, u32 info)
                                 flags & GRE_KEY ?
                                 *(((__be32 *)p) + (grehlen / 4) - 1) : 0,
                                 p[1]);
-        if (t == NULL || t->parms.iph.daddr == 0 ||
+        if (t == NULL)
+                goto out;
+
+        if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
+                ipv4_update_pmtu(skb, dev_net(skb->dev), info,
+                                 t->parms.link, 0, IPPROTO_GRE, 0);
+                goto out;
+        }
+
+        if (t->parms.iph.daddr == 0 ||
             ipv4_is_multicast(t->parms.iph.daddr))
                 goto out;
 
diff --git a/net/ipv4/ipcomp.c b/net/ipv4/ipcomp.c
index 63b64c45a826..b91375482d84 100644
--- a/net/ipv4/ipcomp.c
+++ b/net/ipv4/ipcomp.c
@@ -42,6 +42,7 @@ static void ipcomp4_err(struct sk_buff *skb, u32 info)
                 return;
         NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%pI4\n",
                  spi, &iph->daddr);
+        ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_COMP, 0);
         xfrm_state_put(x);
 }
 
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index 2d0f99bf61b3..715338a1b205 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -348,9 +348,6 @@ static int ipip_err(struct sk_buff *skb, u32 info)
                 case ICMP_PORT_UNREACH:
                         /* Impossible event. */
                         return 0;
-                case ICMP_FRAG_NEEDED:
-                        /* Soft state for pmtu is maintained by IP core. */
-                        return 0;
                 default:
                         /* All others are translated to HOST_UNREACH.
                            rfc2003 contains "deep thoughts" about NET_UNREACH,
@@ -369,7 +366,17 @@ static int ipip_err(struct sk_buff *skb, u32 info)
 
         rcu_read_lock();
         t = ipip_tunnel_lookup(dev_net(skb->dev), iph->daddr, iph->saddr);
-        if (t == NULL || t->parms.iph.daddr == 0)
+        if (t == NULL)
+                goto out;
+
+        if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
+                ipv4_update_pmtu(skb, dev_net(skb->dev), info,
+                                 t->dev->ifindex, 0, IPPROTO_IPIP, 0);
+                err = 0;
+                goto out;
+        }
+
+        if (t->parms.iph.daddr == 0)
                 goto out;
 
         err = 0;
diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 2c00e8bf684d..340fcf29a966 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -371,6 +371,7 @@ void ping_err(struct sk_buff *skb, u32 info)
                 break;
         case ICMP_DEST_UNREACH:
                 if (code == ICMP_FRAG_NEEDED) { /* Path MTU discovery */
+                        ipv4_sk_update_pmtu(skb, sk, info);
                         if (inet_sock->pmtudisc != IP_PMTUDISC_DONT) {
                                 err = EMSGSIZE;
                                 harderr = 1;
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 4032b818f3e4..659ddfb10947 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -216,6 +216,9 @@ static void raw_err(struct sock *sk, struct sk_buff *skb, u32 info)
         int err = 0;
         int harderr = 0;
 
+        if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
+                ipv4_sk_update_pmtu(skb, sk, info);
+
         /* Report error on raw socket, if:
            1. User requested ip_recverr.
            2. Socket is connected (otherwise the error indication
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 655506af47ca..41df5297a412 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1711,6 +1711,34 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, u32 mtu)
         }
 }
 
+void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
+                      int oif, u32 mark, u8 protocol, int flow_flags)
+{
+        const struct iphdr *iph = (const struct iphdr *)skb->data;
+        struct flowi4 fl4;
+        struct rtable *rt;
+
+        flowi4_init_output(&fl4, oif, mark, RT_TOS(iph->tos), RT_SCOPE_UNIVERSE,
+                           protocol, flow_flags | FLOWI_FLAG_PRECOW_METRICS,
+                           iph->daddr, iph->saddr, 0, 0);
+        rt = __ip_route_output_key(net, &fl4);
+        if (!IS_ERR(rt)) {
+                ip_rt_update_pmtu(&rt->dst, mtu);
+                ip_rt_put(rt);
+        }
+}
+EXPORT_SYMBOL_GPL(ipv4_update_pmtu);
+
+void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu)
+{
+        const struct inet_sock *inet = inet_sk(sk);
+
+        return ipv4_update_pmtu(skb, sock_net(sk), mtu,
+                                sk->sk_bound_dev_if, sk->sk_mark,
+                                inet->hdrincl ? IPPROTO_RAW : sk->sk_protocol,
+                                inet_sk_flowi_flags(sk));
+}
+EXPORT_SYMBOL_GPL(ipv4_sk_update_pmtu);
 
 static void ipv4_validate_peer(struct rtable *rt)
 {
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index eaca73644e79..db017efb76ea 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -615,6 +615,7 @@ void __udp4_lib_err(struct sk_buff *skb, u32 info, struct udp_table *udptable)
                 break;
         case ICMP_DEST_UNREACH:
                 if (code == ICMP_FRAG_NEEDED) { /* Path MTU discovery */
+                        ipv4_sk_update_pmtu(skb, sk, info);
                         if (inet->pmtudisc != IP_PMTUDISC_DONT) {
                                 err = EMSGSIZE;
                                 harderr = 1;
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index 60415711563f..49aea94c9be3 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -527,9 +527,6 @@ static int ipip6_err(struct sk_buff *skb, u32 info)
                 case ICMP_PORT_UNREACH:
                         /* Impossible event. */
                         return 0;
-                case ICMP_FRAG_NEEDED:
-                        /* Soft state for pmtu is maintained by IP core. */
-                        return 0;
                 default:
                         /* All others are translated to HOST_UNREACH.
                            rfc2003 contains "deep thoughts" about NET_UNREACH,
@@ -551,7 +548,17 @@ static int ipip6_err(struct sk_buff *skb, u32 info)
                                 skb->dev,
                                 iph->daddr,
                                 iph->saddr);
-        if (t == NULL || t->parms.iph.daddr == 0)
+        if (t == NULL)
+                goto out;
+
+        if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
+                ipv4_update_pmtu(skb, dev_net(skb->dev), info,
+                                 t->dev->ifindex, 0, IPPROTO_IPV6, 0);
+                err = 0;
+                goto out;
+        }
+
+        if (t->parms.iph.daddr == 0)
                 goto out;
 
         err = 0;