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.

---
Repost patch, after fixing some issues pointed out on netdev@ applies clean against current linux-2.6 HEAD

 include/net/ip6_fib.h   |    2 +
 include/net/ip6_route.h |    7 ++++
 net/ipv6/addrconf.c     |    2 +
 net/ipv6/ip6_output.c   |    8 ++--
 net/ipv6/route.c        |   72 +++++++++++++++++++++++++++++++++++++++++++++--
 5 files changed, 84 insertions(+), 7 deletions(-)

---

index bc3cde0..98348d5 100644
@@ -42,6 +42,7 @@ struct fib6_config {
 
 	struct in6_addr	fc_dst;
 	struct in6_addr	fc_src;
+	struct in6_addr	fc_prefsrc;
 	struct in6_addr	fc_gateway;
 
 	unsigned long	fc_expires;

@@ -107,6 +108,7 @@ struct rt6_info {
 	struct rt6key			rt6i_dst ____cacheline_aligned_in_smp;
 	u32				rt6i_flags;
 	struct rt6key			rt6i_src;
+	struct rt6key			rt6i_prefsrc;
 	u32				rt6i_metric;
 	u32				rt6i_peer_genid;
 

index c850e5f..86b1cb4 100644
@@ -84,6 +84,12 @@ extern int			ip6_route_add(struct fib6_config *cfg);
 extern int			ip6_ins_rt(struct rt6_info *);
 extern int			ip6_del_rt(struct rt6_info *);
 
+extern int			ip6_route_get_saddr(struct net *net,
+						    struct rt6_info *rt,
+						    struct in6_addr *daddr,
+						    unsigned int prefs,
+						    struct in6_addr *saddr);
+
 extern struct rt6_info		*rt6_lookup(struct net *net,
 					    const struct in6_addr *daddr,
 					    const struct in6_addr *saddr,

@@ -141,6 +147,7 @@ struct rt6_rtnl_dump_arg {
 extern int rt6_dump_route(struct rt6_info *rt, void *p_arg);
 extern void rt6_ifdown(struct net *net, struct net_device *dev);
 extern void rt6_mtu_change(struct net_device *dev, unsigned mtu);
+extern void rt6_remove_prefsrc(struct inet6_ifaddr *ifp);
 
 
 /*

index 3daaf3c..26f9e14 100644
@@ -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);
 }

index 1820887..0ce081b 100644
@@ -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, dst,
+					  sk ? inet6_sk(sk)->srcprefs : 0,
+					  &fl6->saddr);
 		if (err)
 			goto out_err_release;
 	}

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From: Daniel Walter <[email protected]>
Date: Mon, 11 Apr 2011 09:03:29 +0200

Ok, I can live with this, applied, thanks!

From: David Miller <[email protected]>
Date: Tue, 12 Apr 2011 15:05:11 -0700 (PDT)

Sorry, I had to revert.

Please fix this warning, test your patch, and resubmit it.

net/ipv6/ip6_output.c: In function ‘ip6_dst_lookup_tail’:
net/ipv6/ip6_output.c:936: warning: passing argument 3 of ‘ip6_route_get_saddr’ from incompatible pointer type include/net/ip6_route.h:87: note: expected ‘struct in6_addr *’ but argument is of type ‘struct dst_entry **’

Thanks.