ipv4: Kill rt->rt_{src, dst} usage in IP GRE tunnels.

First, make callers pass on-stack flowi4 to ip_route_output_gre()
so they can get at the fully resolved flow key.

Next, use that in ipgre_tunnel_xmit() to avoid the need to use
rt->rt_{dst,src}.

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 30 insertions, 26 deletions

diff --git a/include/net/route.h b/include/net/route.h
index 8c02c871a8ce..9f8070b251fb 100644
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -152,19 +152,18 @@ static inline struct rtable *ip_route_output_ports(struct net *net, struct flowi
         return ip_route_output_flow(net, fl4, sk);
 }
 
-static inline struct rtable *ip_route_output_gre(struct net *net,
+static inline struct rtable *ip_route_output_gre(struct net *net, struct flowi4 *fl4,
                                                  __be32 daddr, __be32 saddr,
                                                  __be32 gre_key, __u8 tos, int oif)
 {
-        struct flowi4 fl4 = {
-                .flowi4_oif = oif,
-                .daddr = daddr,
-                .saddr = saddr,
-                .flowi4_tos = tos,
-                .flowi4_proto = IPPROTO_GRE,
-                .fl4_gre_key = gre_key,
-        };
-        return ip_route_output_key(net, &fl4);
+        memset(fl4, 0, sizeof(*fl4));
+        fl4->flowi4_oif = oif;
+        fl4->daddr = daddr;
+        fl4->saddr = saddr;
+        fl4->flowi4_tos = tos;
+        fl4->flowi4_proto = IPPROTO_GRE;
+        fl4->fl4_gre_key = gre_key;
+        return ip_route_output_key(net, fl4);
 }
 
 extern int ip_route_input_common(struct sk_buff *skb, __be32 dst, __be32 src,
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 24efd353279a..10e9b5aea070 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -699,6 +699,7 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
         struct pcpu_tstats *tstats;
         const struct iphdr  *old_iph = ip_hdr(skb);
         const struct iphdr  *tiph;
+        struct flowi4 fl4;
         u8     tos;
         __be16 df;
         struct rtable *rt;                      /* Route to the other host */
@@ -769,7 +770,7 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
                         tos = ipv6_get_dsfield((const struct ipv6hdr *)old_iph);
         }
 
-        rt = ip_route_output_gre(dev_net(dev), dst, tiph->saddr,
+        rt = ip_route_output_gre(dev_net(dev), &fl4, dst, tiph->saddr,
                                  tunnel->parms.o_key, RT_TOS(tos),
                                  tunnel->parms.link);
         if (IS_ERR(rt)) {
@@ -873,8 +874,8 @@ static netdev_tx_t ipgre_tunnel_xmit(struct sk_buff *skb, struct net_device *dev
         iph->frag_off           =       df;
         iph->protocol           =       IPPROTO_GRE;
         iph->tos                =       ipgre_ecn_encapsulate(tos, old_iph, skb);
-        iph->daddr              =       rt->rt_dst;
-        iph->saddr              =       rt->rt_src;
+        iph->daddr              =       fl4.daddr;
+        iph->saddr              =       fl4.saddr;
 
         if ((iph->ttl = tiph->ttl) == 0) {
                 if (skb->protocol == htons(ETH_P_IP))
@@ -938,12 +939,14 @@ static int ipgre_tunnel_bind_dev(struct net_device *dev)
         /* Guess output device to choose reasonable mtu and needed_headroom */
 
         if (iph->daddr) {
-                struct rtable *rt = ip_route_output_gre(dev_net(dev),
-                                                        iph->daddr, iph->saddr,
-                                                        tunnel->parms.o_key,
-                                                        RT_TOS(iph->tos),
-                                                        tunnel->parms.link);
-
+                struct flowi4 fl4;
+                struct rtable *rt;
+
+                rt = ip_route_output_gre(dev_net(dev), &fl4,
+                                         iph->daddr, iph->saddr,
+                                         tunnel->parms.o_key,
+                                         RT_TOS(iph->tos),
+                                         tunnel->parms.link);
                 if (!IS_ERR(rt)) {
                         tdev = rt->dst.dev;
                         ip_rt_put(rt);
@@ -1196,13 +1199,15 @@ static int ipgre_open(struct net_device *dev)
         struct ip_tunnel *t = netdev_priv(dev);
 
         if (ipv4_is_multicast(t->parms.iph.daddr)) {
-                struct rtable *rt = ip_route_output_gre(dev_net(dev),
-                                                        t->parms.iph.daddr,
-                                                        t->parms.iph.saddr,
-                                                        t->parms.o_key,
-                                                        RT_TOS(t->parms.iph.tos),
-                                                        t->parms.link);
-
+                struct flowi4 fl4;
+                struct rtable *rt;
+
+                rt = ip_route_output_gre(dev_net(dev), &fl4,
+                                         t->parms.iph.daddr,
+                                         t->parms.iph.saddr,
+                                         t->parms.o_key,
+                                         RT_TOS(t->parms.iph.tos),
+                                         t->parms.link);
                 if (IS_ERR(rt))
                         return -EADDRNOTAVAIL;
                 dev = rt->dst.dev;