ipv6: unshare inetpeers

We currently cow metrics a bit too soon in IPv6 case : All routes are
tied to a single inetpeer entry.

Change ip6_rt_copy() to get destination address as second argument, so
that we fill rt6i_dst before the dst_copy_metrics() call.

icmp6_dst_alloc() must set rt6i_dst before calling dst_metric_set(), or
else the cow is done while rt6i_dst is still NULL.

If orig route points to readonly metrics, we can share the pointer
instead of performing the memory allocation and copy.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 20 insertions, 13 deletions

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index ddef80f568b0..e8987da06667 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -72,7 +72,8 @@
 #define RT6_TRACE(x...) do { ; } while (0)
 #endif
 
-static struct rt6_info * ip6_rt_copy(struct rt6_info *ort);
+static struct rt6_info *ip6_rt_copy(const struct rt6_info *ort,
+                                    const struct in6_addr *dest);
 static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie);
 static unsigned int      ip6_default_advmss(const struct dst_entry *dst);
 static unsigned int      ip6_default_mtu(const struct dst_entry *dst);
@@ -690,7 +691,8 @@ int ip6_ins_rt(struct rt6_info *rt)
         return __ip6_ins_rt(rt, &info);
 }
 
-static struct rt6_info *rt6_alloc_cow(struct rt6_info *ort, const struct in6_addr *daddr,
+static struct rt6_info *rt6_alloc_cow(const struct rt6_info *ort,
+                                      const struct in6_addr *daddr,
                                       const struct in6_addr *saddr)
 {
         struct rt6_info *rt;
@@ -699,7 +701,7 @@ static struct rt6_info *rt6_alloc_cow(struct rt6_info *ort, const struct in6_add
          *      Clone the route.
          */
 
-        rt = ip6_rt_copy(ort);
+        rt = ip6_rt_copy(ort, daddr);
 
         if (rt) {
                 struct neighbour *neigh;
@@ -707,12 +709,11 @@ static struct rt6_info *rt6_alloc_cow(struct rt6_info *ort, const struct in6_add
 
                 if (!(rt->rt6i_flags&RTF_GATEWAY)) {
                         if (rt->rt6i_dst.plen != 128 &&
-                            ipv6_addr_equal(&rt->rt6i_dst.addr, daddr))
+                            ipv6_addr_equal(&ort->rt6i_dst.addr, daddr))
                                 rt->rt6i_flags |= RTF_ANYCAST;
                         ipv6_addr_copy(&rt->rt6i_gateway, daddr);
                 }
 
-                ipv6_addr_copy(&rt->rt6i_dst.addr, daddr);
                 rt->rt6i_dst.plen = 128;
                 rt->rt6i_flags |= RTF_CACHE;
                 rt->dst.flags |= DST_HOST;
@@ -759,11 +760,12 @@ static struct rt6_info *rt6_alloc_cow(struct rt6_info *ort, const struct in6_add
         return rt;
 }
 
-static struct rt6_info *rt6_alloc_clone(struct rt6_info *ort, const struct in6_addr *daddr)
+static struct rt6_info *rt6_alloc_clone(struct rt6_info *ort,
+                                        const struct in6_addr *daddr)
 {
-        struct rt6_info *rt = ip6_rt_copy(ort);
+        struct rt6_info *rt = ip6_rt_copy(ort, daddr);
+
         if (rt) {
-                ipv6_addr_copy(&rt->rt6i_dst.addr, daddr);
                 rt->rt6i_dst.plen = 128;
                 rt->rt6i_flags |= RTF_CACHE;
                 rt->dst.flags |= DST_HOST;
@@ -907,7 +909,10 @@ struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_ori
                 new->input = dst_discard;
                 new->output = dst_discard;
 
-                dst_copy_metrics(new, &ort->dst);
+                if (dst_metrics_read_only(&ort->dst))
+                        new->_metrics = ort->dst._metrics;
+                else
+                        dst_copy_metrics(new, &ort->dst);
                 rt->rt6i_idev = ort->rt6i_idev;
                 if (rt->rt6i_idev)
                         in6_dev_hold(rt->rt6i_idev);
@@ -1067,6 +1072,7 @@ struct dst_entry *icmp6_dst_alloc(struct net_device *dev,
         rt->rt6i_idev     = idev;
         dst_set_neighbour(&rt->dst, neigh);
         atomic_set(&rt->dst.__refcnt, 1);
+        ipv6_addr_copy(&rt->rt6i_dst.addr, addr);
         dst_metric_set(&rt->dst, RTAX_HOPLIMIT, 255);
         rt->dst.output  = ip6_output;
 
@@ -1584,7 +1590,7 @@ void rt6_redirect(const struct in6_addr *dest, const struct in6_addr *src,
         if (neigh == dst_get_neighbour(&rt->dst))
                 goto out;
 
-        nrt = ip6_rt_copy(rt);
+        nrt = ip6_rt_copy(rt, dest);
         if (nrt == NULL)
                 goto out;
 
@@ -1592,7 +1598,6 @@ void rt6_redirect(const struct in6_addr *dest, const struct in6_addr *src,
         if (on_link)
                 nrt->rt6i_flags &= ~RTF_GATEWAY;
 
-        ipv6_addr_copy(&nrt->rt6i_dst.addr, dest);
         nrt->rt6i_dst.plen = 128;
         nrt->dst.flags |= DST_HOST;
 
@@ -1730,7 +1735,8 @@ void rt6_pmtu_discovery(const struct in6_addr *daddr, const struct in6_addr *sad
  *      Misc support functions
  */
 
-static struct rt6_info * ip6_rt_copy(struct rt6_info *ort)
+static struct rt6_info *ip6_rt_copy(const struct rt6_info *ort,
+                                    const struct in6_addr *dest)
 {
         struct net *net = dev_net(ort->rt6i_dev);
         struct rt6_info *rt = ip6_dst_alloc(&net->ipv6.ip6_dst_ops,
@@ -1740,6 +1746,8 @@ static struct rt6_info * ip6_rt_copy(struct rt6_info *ort)
                 rt->dst.input = ort->dst.input;
                 rt->dst.output = ort->dst.output;
 
+                ipv6_addr_copy(&rt->rt6i_dst.addr, dest);
+                rt->rt6i_dst.plen = ort->rt6i_dst.plen;
                 dst_copy_metrics(&rt->dst, &ort->dst);
                 rt->dst.error = ort->dst.error;
                 rt->rt6i_idev = ort->rt6i_idev;
@@ -1752,7 +1760,6 @@ static struct rt6_info * ip6_rt_copy(struct rt6_info *ort)
                 rt->rt6i_flags = ort->rt6i_flags & ~RTF_EXPIRES;
                 rt->rt6i_metric = 0;
 
-                memcpy(&rt->rt6i_dst, &ort->rt6i_dst, sizeof(struct rt6key));
 #ifdef CONFIG_IPV6_SUBTREES
                 memcpy(&rt->rt6i_src, &ort->rt6i_src, sizeof(struct rt6key));
 #endif