4.2.8-ckt12 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Daniel Borkmann <daniel@iogearbox.net>

commit 47e27d5e92c46a3a62d4dfd8895b1ddb8613f531 upstream.

The original tokenized iid support implemented via f53adae4eae5 ("net: ipv6:
add tokenized interface identifier support") didn't allow for clearing a
device token as it was intended that this addressing mode was the only one
active for globally scoped IPv6 addresses. Later we relaxed that restriction
via 617fe29d45bd ("net: ipv6: only invalidate previously tokenized addresses"),
and we should also allow for clearing tokens as there's no good reason why
it shouldn't be allowed.

Fixes: 617fe29d45bd ("net: ipv6: only invalidate previously tokenized addresses")
Reported-by: Robin H. Johnson <redacted>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Hannes Frederic Sowa <redacted>
Acked-by: Hannes Frederic Sowa <redacted>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Kamal Mostafa <redacted>
---
 net/ipv6/addrconf.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 335f495..135f1b8 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c

@@ -4737,15 +4737,13 @@ static int inet6_set_iftoken(struct inet6_dev *idev, struct in6_addr *token)
 {
 	struct inet6_ifaddr *ifp;
 	struct net_device *dev = idev->dev;
-	bool update_rs = false;
+	bool clear_token, update_rs = false;
 	struct in6_addr ll_addr;
 
 	ASSERT_RTNL();
 
 	if (!token)
 		return -EINVAL;
-	if (ipv6_addr_any(token))
-		return -EINVAL;
 	if (dev->flags & (IFF_LOOPBACK | IFF_NOARP))
 		return -EINVAL;
 	if (!ipv6_accept_ra(idev))

@@ -4760,10 +4758,13 @@ static int inet6_set_iftoken(struct inet6_dev *idev, struct in6_addr *token)
 
 	write_unlock_bh(&idev->lock);
 
+	clear_token = ipv6_addr_any(token);
+	if (clear_token)
+		goto update_lft;
+
 	if (!idev->dead && (idev->if_flags & IF_READY) &&
 	    !ipv6_get_lladdr(dev, &ll_addr, IFA_F_TENTATIVE |
 			     IFA_F_OPTIMISTIC)) {
-
 		/* If we're not ready, then normal ifup will take care
 		 * of this. Otherwise, we need to request our rs here.
 		 */

@@ -4771,6 +4772,7 @@ static int inet6_set_iftoken(struct inet6_dev *idev, struct in6_addr *token)
 		update_rs = true;
 	}
 
+update_lft:
 	write_lock_bh(&idev->lock);
 
 	if (update_rs) {

-- 
2.7.4