[IPV6] address: Support NLM_F_EXCL when adding addresses

iproute2 doesn't provide the NLM_F_CREATE flag when adding addresses,
it is assumed to be implied. The existing code issues a check on
said flag when the modify operation fails (likely due to ENOENT)
before continueing to create it, this leads to a hard to predict
result, therefore the NLM_F_CREATE check is removed.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index bb18b9c3a5cba43f9d33570e4aae804375cfcf64..1e5a296d0a82d7517e1bf347a4aabc494d5ca50e 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2908,24 +2908,14 @@ 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(int ifindex, struct in6_addr *pfx,
-                 __u32 prefered_lft, __u32 valid_lft)
+static int inet6_addr_modify(struct inet6_ifaddr *ifp, u32 prefered_lft,
+                            u32 valid_lft)
 {
-       struct inet6_ifaddr *ifp = NULL;
-       struct net_device *dev;
        int ifa_flags = 0;
 
-       if ((dev = __dev_get_by_index(ifindex)) == NULL)
-               return -ENODEV;
-
        if (!valid_lft || (prefered_lft > valid_lft))
                return -EINVAL;
 
-       ifp = ipv6_get_ifaddr(pfx, dev, 1);
-       if (ifp == NULL)
-               return -ENOENT;
-
        if (valid_lft == INFINITY_LIFE_TIME)
                ifa_flags = IFA_F_PERMANENT;
        else if (valid_lft >= 0x7FFFFFFF/HZ)
@@ -2947,7 +2937,6 @@ inet6_addr_modify(int ifindex, struct in6_addr *pfx,
        spin_unlock_bh(&ifp->lock);
        if (!(ifp->flags&IFA_F_TENTATIVE))
                ipv6_ifa_notify(0, ifp);
-       in6_ifa_put(ifp);
 
        addrconf_verify(0);
 
@@ -2960,6 +2949,8 @@ inet6_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
        struct ifaddrmsg *ifm;
        struct nlattr *tb[IFA_MAX+1];
        struct in6_addr *pfx;
+       struct inet6_ifaddr *ifa;
+       struct net_device *dev;
        u32 valid_lft, preferred_lft;
        int err;
 
@@ -2983,15 +2974,29 @@ inet6_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
                valid_lft = INFINITY_LIFE_TIME;
        }
 
-       if (nlh->nlmsg_flags & NLM_F_REPLACE) {
-               err = inet6_addr_modify(ifm->ifa_index, pfx,
-                                       preferred_lft, valid_lft);
-               if (err == 0 || !(nlh->nlmsg_flags & NLM_F_CREATE))
-                       return err;
+       dev =  __dev_get_by_index(ifm->ifa_index);
+       if (dev == NULL)
+               return -ENODEV;
+
+       ifa = ipv6_get_ifaddr(pfx, dev, 1);
+       if (ifa == NULL) {
+               /*
+                * It would be best to check for !NLM_F_CREATE here but
+                * userspace alreay relies on not having to provide this.
+                */
+               return inet6_addr_add(ifm->ifa_index, pfx, ifm->ifa_prefixlen,
+                                     preferred_lft, valid_lft);
        }
 
-       return inet6_addr_add(ifm->ifa_index, pfx, ifm->ifa_prefixlen,
-                             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);
+
+       in6_ifa_put(ifa);
+
+       return err;
 }
 
 static void put_ifaddrmsg(struct nlmsghdr *nlh, u8 prefixlen, u8 flags,