ip_tunnel(ipv4): fix tunnels with "local any remote $remote_ip"

Ipv4 tunnels created with "local any remote $ip" didn't work properly since
7d442fab0 (ipv4: Cache dst in tunnels). 99% of packets sent via those tunnels
had src addr = 0.0.0.0. That was because only dst_entry was cached, although
fl4.saddr has to be cached too. Every time ip_tunnel_xmit used cached dst_entry
(tunnel_rtable_get returned non-NULL), fl4.saddr was initialized with
tnl_params->saddr (= 0 in our case), and wasn't changed until iptunnel_xmit().

This patch adds saddr to ip_tunnel->dst_cache, fixing this issue.

Reported-by: Sergey Popov <pinkbyte@gentoo.org>
Signed-off-by: Dmitry Popov <ixaphire@qrator.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 18 insertions, 11 deletions

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 6f9de61dce5f..45920d928341 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -69,23 +69,25 @@ static unsigned int ip_tunnel_hash(__be32 key, __be32 remote)
 }
 
 static void __tunnel_dst_set(struct ip_tunnel_dst *idst,
-                             struct dst_entry *dst)
+                             struct dst_entry *dst, __be32 saddr)
 {
         struct dst_entry *old_dst;
 
         dst_clone(dst);
         old_dst = xchg((__force struct dst_entry **)&idst->dst, dst);
         dst_release(old_dst);
+        idst->saddr = saddr;
 }
 
-static void tunnel_dst_set(struct ip_tunnel *t, struct dst_entry *dst)
+static void tunnel_dst_set(struct ip_tunnel *t,
+                           struct dst_entry *dst, __be32 saddr)
 {
-        __tunnel_dst_set(this_cpu_ptr(t->dst_cache), dst);
+        __tunnel_dst_set(this_cpu_ptr(t->dst_cache), dst, saddr);
 }
 
 static void tunnel_dst_reset(struct ip_tunnel *t)
 {
-        tunnel_dst_set(t, NULL);
+        tunnel_dst_set(t, NULL, 0);
 }
 
 void ip_tunnel_dst_reset_all(struct ip_tunnel *t)
@@ -93,20 +95,25 @@ void ip_tunnel_dst_reset_all(struct ip_tunnel *t)
         int i;
 
         for_each_possible_cpu(i)
-                __tunnel_dst_set(per_cpu_ptr(t->dst_cache, i), NULL);
+                __tunnel_dst_set(per_cpu_ptr(t->dst_cache, i), NULL, 0);
 }
 EXPORT_SYMBOL(ip_tunnel_dst_reset_all);
 
-static struct rtable *tunnel_rtable_get(struct ip_tunnel *t, u32 cookie)
+static struct rtable *tunnel_rtable_get(struct ip_tunnel *t,
+                                        u32 cookie, __be32 *saddr)
 {
+        struct ip_tunnel_dst *idst;
         struct dst_entry *dst;
 
         rcu_read_lock();
-        dst = rcu_dereference(this_cpu_ptr(t->dst_cache)->dst);
+        idst = this_cpu_ptr(t->dst_cache);
+        dst = rcu_dereference(idst->dst);
         if (dst && !atomic_inc_not_zero(&dst->__refcnt))
                 dst = NULL;
         if (dst) {
-                if (dst->obsolete && dst->ops->check(dst, cookie) == NULL) {
+                if (!dst->obsolete || dst->ops->check(dst, cookie)) {
+                        *saddr = idst->saddr;
+                } else {
                         tunnel_dst_reset(t);
                         dst_release(dst);
                         dst = NULL;
@@ -367,7 +374,7 @@ static int ip_tunnel_bind_dev(struct net_device *dev)
 
                 if (!IS_ERR(rt)) {
                         tdev = rt->dst.dev;
-                        tunnel_dst_set(tunnel, &rt->dst);
+                        tunnel_dst_set(tunnel, &rt->dst, fl4.saddr);
                         ip_rt_put(rt);
                 }
                 if (dev->type != ARPHRD_ETHER)
@@ -610,7 +617,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
         init_tunnel_flow(&fl4, protocol, dst, tnl_params->saddr,
                          tunnel->parms.o_key, RT_TOS(tos), tunnel->parms.link);
 
-        rt = connected ? tunnel_rtable_get(tunnel, 0) : NULL;
+        rt = connected ? tunnel_rtable_get(tunnel, 0, &fl4.saddr) : NULL;
 
         if (!rt) {
                 rt = ip_route_output_key(tunnel->net, &fl4);
@@ -620,7 +627,7 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
                         goto tx_error;
                 }
                 if (connected)
-                        tunnel_dst_set(tunnel, &rt->dst);
+                        tunnel_dst_set(tunnel, &rt->dst, fl4.saddr);
         }
 
         if (rt->dst.dev == dev) {