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>

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index e11f10eceffc989ef1b68beb57b24b564c467400..e7a1882db048289c710b957fa5e9c6b99941f4f5 100644 (file)
--- 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)