ipip: only increase err_count for some certain type icmp in ipip_err

t->err_count is used to count the link failure on tunnel and an err
will be reported to user socket in tx path if t->err_count is not 0.
udp socket could even return EHOSTUNREACH to users.

Since commit fd58156e456d ("IPIP: Use ip-tunneling code.") removed
the 'switch check' for icmp type in ipip_err(), err_count would be
increased by the icmp packet with ICMP_EXC_FRAGTIME code. an link
failure would be reported out due to this.

In Jianlin's case, when receiving ICMP_EXC_FRAGTIME a icmp packet,
udp netperf failed with the err:
  send_data: data send error: No route to host (errno 113)

We expect this error reported from tunnel to socket when receiving
some certain type icmp, but not ICMP_EXC_FRAGTIME, ICMP_SR_FAILED
or ICMP_PARAMETERPROB ones.

This patch is to bring 'switch check' for icmp type back to ipip_err
so that it only reports link failure for the right type icmp, just as
in ipgre_err() and ipip6_err().

Fixes: fd58156e456d ("IPIP: Use ip-tunneling code.")
Reported-by: Jianlin Shi <jishi@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 42 insertions, 17 deletions

diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index fb1ad22b5e29..cdd627355ed1 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -128,43 +128,68 @@ static struct rtnl_link_ops ipip_link_ops __read_mostly;
 
 static int ipip_err(struct sk_buff *skb, u32 info)
 {
-
-/* All the routers (except for Linux) return only
-   8 bytes of packet payload. It means, that precise relaying of
-   ICMP in the real Internet is absolutely infeasible.
- */
+        /* All the routers (except for Linux) return only
+         * 8 bytes of packet payload. It means, that precise relaying of
+         * ICMP in the real Internet is absolutely infeasible.
+         */
         struct net *net = dev_net(skb->dev);
         struct ip_tunnel_net *itn = net_generic(net, ipip_net_id);
         const struct iphdr *iph = (const struct iphdr *)skb->data;
-        struct ip_tunnel *t;
-        int err;
         const int type = icmp_hdr(skb)->type;
         const int code = icmp_hdr(skb)->code;
+        struct ip_tunnel *t;
+        int err = 0;
+
+        switch (type) {
+        case ICMP_DEST_UNREACH:
+                switch (code) {
+                case ICMP_SR_FAILED:
+                        /* Impossible event. */
+                        goto out;
+                default:
+                        /* All others are translated to HOST_UNREACH.
+                         * rfc2003 contains "deep thoughts" about NET_UNREACH,
+                         * I believe they are just ether pollution. --ANK
+                         */
+                        break;
+                }
+                break;
+
+        case ICMP_TIME_EXCEEDED:
+                if (code != ICMP_EXC_TTL)
+                        goto out;
+                break;
+
+        case ICMP_REDIRECT:
+                break;
+
+        default:
+                goto out;
+        }
 
-        err = -ENOENT;
         t = ip_tunnel_lookup(itn, skb->dev->ifindex, TUNNEL_NO_KEY,
                              iph->daddr, iph->saddr, 0);
-        if (!t)
+        if (!t) {
+                err = -ENOENT;
                 goto out;
+        }
 
         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
-                ipv4_update_pmtu(skb, dev_net(skb->dev), info,
-                                 t->parms.link, 0, iph->protocol, 0);
-                err = 0;
+                ipv4_update_pmtu(skb, net, info, t->parms.link, 0,
+                                 iph->protocol, 0);
                 goto out;
         }
 
         if (type == ICMP_REDIRECT) {
-                ipv4_redirect(skb, dev_net(skb->dev), t->parms.link, 0,
-                              iph->protocol, 0);
-                err = 0;
+                ipv4_redirect(skb, net, t->parms.link, 0, iph->protocol, 0);
                 goto out;
         }
 
-        if (t->parms.iph.daddr == 0)
+        if (t->parms.iph.daddr == 0) {
+                err = -ENOENT;
                 goto out;
+        }
 
-        err = 0;
         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
                 goto out;