IPv6: do not create temporary adresses with too short preferred lifetime

From RFC341:
A temporary address is created only if this calculated Preferred
Lifetime is greater than REGEN_ADVANCE time units.  In particular, an
implementation must not create a temporary address with a zero
Preferred Lifetime.

Signed-off-by: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 0 deletions

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index e11f10eceffc..e7a1882db048 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -776,6 +776,7 @@ static int ipv6_create_tempaddr(struct inet6_ifaddr *ifp, struct inet6_ifaddr *i
         struct inet6_dev *idev = ifp->idev;
         struct in6_addr addr, *tmpaddr;
         unsigned long tmp_prefered_lft, tmp_valid_lft, tmp_cstamp, tmp_tstamp;
+        unsigned long regen_advance;
         int tmp_plen;
         int ret = 0;
         int max_addresses;
@@ -836,8 +837,23 @@ retry:
         tmp_tstamp = ifp->tstamp;
         spin_unlock_bh(&ifp->lock);
 
+        regen_advance = idev->cnf.regen_max_retry *
+                        idev->cnf.dad_transmits *
+                        idev->nd_parms->retrans_time / HZ;
         write_unlock(&idev->lock);
 
+        /* A temporary address is created only if this calculated Preferred
+         * Lifetime is greater than REGEN_ADVANCE time units.  In particular,
+         * an implementation must not create a temporary address with a zero
+         * Preferred Lifetime.
+         */
+        if (tmp_prefered_lft <= regen_advance) {
+                in6_ifa_put(ifp);
+                in6_dev_put(idev);
+                ret = -1;
+                goto out;
+        }
+
         addr_flags = IFA_F_TEMPORARY;
         /* set in addrconf_prefix_rcv() */
         if (ifp->flags & IFA_F_OPTIMISTIC)