[IPV6] ADDRCONF: Allow non-DAD'able addresses.

IFA_F_NODAD flag, similar to IN6_IFF_NODAD in BSDs, is introduced
to skip DAD.

This flag should be set to Mobile IPv6 Home Address(es) on Mobile
Node because DAD would fail if we should perform DAD; our Home Agent
protects our Home Address(es).

Signed-off-by: Noriaki TAKAMIYA <takamiya@po.ntts.co.jp>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 17 insertions, 15 deletions

diff --git a/include/linux/if_addr.h b/include/linux/if_addr.h
index e1590454db59..ca24b9de13fb 100644
--- a/include/linux/if_addr.h
+++ b/include/linux/if_addr.h
@@ -38,6 +38,7 @@ enum
 #define IFA_F_SECONDARY         0x01
 #define IFA_F_TEMPORARY         IFA_F_SECONDARY
 
+#define IFA_F_NODAD             0x02
 #define IFA_F_DEPRECATED        0x20
 #define IFA_F_TENTATIVE         0x40
 #define IFA_F_PERMANENT         0x80
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index c09ebb7bb98a..adb583a26151 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1873,12 +1873,11 @@ err_exit:
  *      Manual configuration of address on an interface
  */
 static int inet6_addr_add(int ifindex, struct in6_addr *pfx, int plen,
-                          __u32 prefered_lft, __u32 valid_lft)
+                          __u8 ifa_flags, __u32 prefered_lft, __u32 valid_lft)
 {
         struct inet6_ifaddr *ifp;
         struct inet6_dev *idev;
         struct net_device *dev;
-        __u8 ifa_flags = 0;
         int scope;
 
         ASSERT_RTNL();
@@ -1971,7 +1970,7 @@ int addrconf_add_ifaddr(void __user *arg)
 
         rtnl_lock();
         err = inet6_addr_add(ireq.ifr6_ifindex, &ireq.ifr6_addr, ireq.ifr6_prefixlen,
-                             INFINITY_LIFE_TIME, INFINITY_LIFE_TIME);
+                             IFA_F_PERMANENT, INFINITY_LIFE_TIME, INFINITY_LIFE_TIME);
         rtnl_unlock();
         return err;
 }
@@ -2514,7 +2513,8 @@ static void addrconf_dad_start(struct inet6_ifaddr *ifp, u32 flags)
         spin_lock_bh(&ifp->lock);
 
         if (dev->flags&(IFF_NOARP|IFF_LOOPBACK) ||
-            !(ifp->flags&IFA_F_TENTATIVE)) {
+            !(ifp->flags&IFA_F_TENTATIVE) ||
+            ifp->flags & IFA_F_NODAD) {
                 ifp->flags &= ~IFA_F_TENTATIVE;
                 spin_unlock_bh(&ifp->lock);
                 read_unlock_bh(&idev->lock);
@@ -2912,28 +2912,25 @@ inet6_rtm_deladdr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
         return inet6_addr_del(ifm->ifa_index, pfx, ifm->ifa_prefixlen);
 }
 
-static int inet6_addr_modify(struct inet6_ifaddr *ifp, u32 prefered_lft,
-                             u32 valid_lft)
+static int inet6_addr_modify(struct inet6_ifaddr *ifp, u8 ifa_flags,
+                             u32 prefered_lft, u32 valid_lft)
 {
-        int ifa_flags = 0;
-
         if (!valid_lft || (prefered_lft > valid_lft))
                 return -EINVAL;
 
         if (valid_lft == INFINITY_LIFE_TIME)
-                ifa_flags = IFA_F_PERMANENT;
+                ifa_flags |= IFA_F_PERMANENT;
         else if (valid_lft >= 0x7FFFFFFF/HZ)
                 valid_lft = 0x7FFFFFFF/HZ;
 
         if (prefered_lft == 0)
-                ifa_flags = IFA_F_DEPRECATED;
+                ifa_flags |= IFA_F_DEPRECATED;
         else if ((prefered_lft >= 0x7FFFFFFF/HZ) &&
                  (prefered_lft != INFINITY_LIFE_TIME))
                 prefered_lft = 0x7FFFFFFF/HZ;
 
         spin_lock_bh(&ifp->lock);
-        ifp->flags = (ifp->flags & ~(IFA_F_DEPRECATED|IFA_F_PERMANENT)) | ifa_flags;
-
+        ifp->flags = (ifp->flags & ~(IFA_F_DEPRECATED | IFA_F_PERMANENT | IFA_F_NODAD)) | ifa_flags;
         ifp->tstamp = jiffies;
         ifp->valid_lft = valid_lft;
         ifp->prefered_lft = prefered_lft;
@@ -2955,7 +2952,8 @@ inet6_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
         struct in6_addr *pfx;
         struct inet6_ifaddr *ifa;
         struct net_device *dev;
-        u32 valid_lft, preferred_lft;
+        u32 valid_lft = INFINITY_LIFE_TIME, preferred_lft = INFINITY_LIFE_TIME;
+        u8 ifa_flags;
         int err;
 
         err = nlmsg_parse(nlh, sizeof(*ifm), tb, IFA_MAX, ifa_ipv6_policy);
@@ -2982,6 +2980,9 @@ inet6_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
         if (dev == NULL)
                 return -ENODEV;
 
+        /* We ignore other flags so far. */
+        ifa_flags = ifm->ifa_flags & IFA_F_NODAD;
+
         ifa = ipv6_get_ifaddr(pfx, dev, 1);
         if (ifa == NULL) {
                 /*
@@ -2989,14 +2990,14 @@ inet6_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
                  * userspace alreay relies on not having to provide this.
                  */
                 return inet6_addr_add(ifm->ifa_index, pfx, ifm->ifa_prefixlen,
-                                      preferred_lft, valid_lft);
+                                      ifa_flags, preferred_lft, valid_lft);
         }
 
         if (nlh->nlmsg_flags & NLM_F_EXCL ||
             !(nlh->nlmsg_flags & NLM_F_REPLACE))
                 err = -EEXIST;
         else
-                err = inet6_addr_modify(ifa, preferred_lft, valid_lft);
+                err = inet6_addr_modify(ifa, ifa_flags, preferred_lft, valid_lft);
 
         in6_ifa_put(ifa);