ipv6: RTA_PREFSRC support for ipv6 route source address selection

[ipv6] Add support for RTA_PREFSRC

This patch allows a user to select the preferred source address
for a specific IPv6-Route. It can be set via a netlink message
setting RTA_PREFSRC to a valid IPv6 address which must be
up on the device the route will be bound to.

Signed-off-by: Daniel Walter <dwalter@barracuda.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 75 insertions, 7 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 1493534116df..129d7e1f311c 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -825,6 +825,8 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
                 dst_release(&rt->dst);
         }
 
+        /* clean up prefsrc entries */
+        rt6_remove_prefsrc(ifp);
 out:
         in6_ifa_put(ifp);
 }
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 46cf7bea6769..c614d02bf429 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -930,10 +930,10 @@ static int ip6_dst_lookup_tail(struct sock *sk,
                 goto out_err_release;
 
         if (ipv6_addr_any(&fl6->saddr)) {
-                err = ipv6_dev_get_saddr(net, ip6_dst_idev(*dst)->dev,
-                                         &fl6->daddr,
-                                         sk ? inet6_sk(sk)->srcprefs : 0,
-                                         &fl6->saddr);
+                struct rt6_info *rt = (struct rt6_info *) *dst;
+                err = ip6_route_get_saddr(net, rt, &fl6->daddr,
+                                          sk ? inet6_sk(sk)->srcprefs : 0,
+                                          &fl6->saddr);
                 if (err)
                         goto out_err_release;
         }
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 843406f14d7b..af26cc1073cb 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1325,6 +1325,16 @@ int ip6_route_add(struct fib6_config *cfg)
         if (dev == NULL)
                 goto out;
 
+        if (!ipv6_addr_any(&cfg->fc_prefsrc)) {
+                if (!ipv6_chk_addr(net, &cfg->fc_prefsrc, dev, 0)) {
+                        err = -EINVAL;
+                        goto out;
+                }
+                ipv6_addr_copy(&rt->rt6i_prefsrc.addr, &cfg->fc_prefsrc);
+                rt->rt6i_prefsrc.plen = 128;
+        } else
+                rt->rt6i_prefsrc.plen = 0;
+
         if (cfg->fc_flags & (RTF_GATEWAY | RTF_NONEXTHOP)) {
                 rt->rt6i_nexthop = __neigh_lookup_errno(&nd_tbl, &rt->rt6i_gateway, dev);
                 if (IS_ERR(rt->rt6i_nexthop)) {
@@ -2037,6 +2047,55 @@ struct rt6_info *addrconf_dst_alloc(struct inet6_dev *idev,
         return rt;
 }
 
+int ip6_route_get_saddr(struct net *net,
+                        struct rt6_info *rt,
+                        struct in6_addr *daddr,
+                        unsigned int prefs,
+                        struct in6_addr *saddr)
+{
+        struct inet6_dev *idev = ip6_dst_idev((struct dst_entry*)rt);
+        int err = 0;
+        if (rt->rt6i_prefsrc.plen)
+                ipv6_addr_copy(saddr, &rt->rt6i_prefsrc.addr);
+        else
+                err = ipv6_dev_get_saddr(net, idev ? idev->dev : NULL,
+                                         daddr, prefs, saddr);
+        return err;
+}
+
+/* remove deleted ip from prefsrc entries */
+struct arg_dev_net_ip {
+        struct net_device *dev;
+        struct net *net;
+        struct in6_addr *addr;
+};
+
+static int fib6_remove_prefsrc(struct rt6_info *rt, void *arg)
+{
+        struct net_device *dev = ((struct arg_dev_net_ip *)arg)->dev;
+        struct net *net = ((struct arg_dev_net_ip *)arg)->net;
+        struct in6_addr *addr = ((struct arg_dev_net_ip *)arg)->addr;
+
+        if (((void *)rt->rt6i_dev == dev || dev == NULL) &&
+            rt != net->ipv6.ip6_null_entry &&
+            ipv6_addr_equal(addr, &rt->rt6i_prefsrc.addr)) {
+                /* remove prefsrc entry */
+                rt->rt6i_prefsrc.plen = 0;
+        }
+        return 0;
+}
+
+void rt6_remove_prefsrc(struct inet6_ifaddr *ifp)
+{
+        struct net *net = dev_net(ifp->idev->dev);
+        struct arg_dev_net_ip adni = {
+                .dev = ifp->idev->dev,
+                .net = net,
+                .addr = &ifp->addr,
+        };
+        fib6_clean_all(net, fib6_remove_prefsrc, 0, &adni);
+}
+
 struct arg_dev_net {
         struct net_device *dev;
         struct net *net;
@@ -2183,6 +2242,9 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
                 nla_memcpy(&cfg->fc_src, tb[RTA_SRC], plen);
         }
 
+        if (tb[RTA_PREFSRC])
+                nla_memcpy(&cfg->fc_prefsrc, tb[RTA_PREFSRC], 16);
+
         if (tb[RTA_OIF])
                 cfg->fc_ifindex = nla_get_u32(tb[RTA_OIF]);
 
@@ -2325,13 +2387,17 @@ static int rt6_fill_node(struct net *net,
 #endif
                         NLA_PUT_U32(skb, RTA_IIF, iif);
         } else if (dst) {
-                struct inet6_dev *idev = ip6_dst_idev(&rt->dst);
                 struct in6_addr saddr_buf;
-                if (ipv6_dev_get_saddr(net, idev ? idev->dev : NULL,
-                                       dst, 0, &saddr_buf) == 0)
+                if (ip6_route_get_saddr(net, rt, dst, 0, &saddr_buf) == 0)
                         NLA_PUT(skb, RTA_PREFSRC, 16, &saddr_buf);
         }
 
+        if (rt->rt6i_prefsrc.plen) {
+                struct in6_addr saddr_buf;
+                ipv6_addr_copy(&saddr_buf, &rt->rt6i_prefsrc.addr);
+                NLA_PUT(skb, RTA_PREFSRC, 16, &saddr_buf);
+        }
+
         if (rtnetlink_put_metrics(skb, dst_metrics_ptr(&rt->dst)) < 0)
                 goto nla_put_failure;