ipv6: enable anycast addresses as source addresses for datagrams

This change allows to consider an anycast address valid as source address
when given via an IPV6_PKTINFO or IPV6_2292PKTINFO ancillary data item.
So, when sending a datagram with ancillary data, the unicast and anycast
addresses are handled in the same way.

- Adds ipv6_chk_acast_addr_src() to check if an anycast address is link-local
  on given interface or is global.
- Uses it in ip6_datagram_send_ctl().

Signed-off-by: Francois-Xavier Le Bail <fx.lebail@yahoo.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 14 insertions, 1 deletions

diff --git a/net/ipv6/anycast.c b/net/ipv6/anycast.c
index 5a80f15a9de2..210183244689 100644
--- a/net/ipv6/anycast.c
+++ b/net/ipv6/anycast.c
@@ -383,6 +383,17 @@ bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
         return found;
 }
 
+/*      check if this anycast address is link-local on given interface or
+ *      is global
+ */
+bool ipv6_chk_acast_addr_src(struct net *net, struct net_device *dev,
+                             const struct in6_addr *addr)
+{
+        return ipv6_chk_acast_addr(net,
+                                   (ipv6_addr_type(addr) & IPV6_ADDR_LINKLOCAL ?
+                                    dev : NULL),
+                                   addr);
+}
 
 #ifdef CONFIG_PROC_FS
 struct ac6_iter_state {
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 2f5e2f154d21..c3bf2d2e519e 100644
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -699,7 +699,9 @@ int ip6_datagram_send_ctl(struct net *net, struct sock *sk,
                                 int strict = __ipv6_addr_src_scope(addr_type) <= IPV6_ADDR_SCOPE_LINKLOCAL;
                                 if (!(inet_sk(sk)->freebind || inet_sk(sk)->transparent) &&
                                     !ipv6_chk_addr(net, &src_info->ipi6_addr,
-                                                   strict ? dev : NULL, 0))
+                                                   strict ? dev : NULL, 0) &&
+                                    !ipv6_chk_acast_addr_src(net, dev,
+                                                             &src_info->ipi6_addr))
                                         err = -EINVAL;
                                 else
                                         fl6->saddr = src_info->ipi6_addr;