rtnetlink: fix link attribute validation with IFLA_GROUP

rtnl_group_changelink() is invoked by rtnl_newlink() before the link
attributes have been validated. Additionally the group changes are
performed even if NLM_F_CREATE is specified and a new link is
created, while more reasonable semantics would be to set the group
value on the newly created link.

Fix both problems by moving the rtnl_group_changelink() invocation
down to the handling of non-existant links without NLM_F_CREATE()
and add a dev_set_group() call to rtnl_create_link().

Signed-off-by: Patrick McHardy <kaber@trash.net>
Acked-by: Vlad Dogaru <ddvlad@rosedu.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 5 deletions

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index a0b2eeb3b610..310eb804e092 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1548,6 +1548,8 @@ struct net_device *rtnl_create_link(struct net *src_net, struct net *net,
                 set_operstate(dev, nla_get_u8(tb[IFLA_OPERSTATE]));
         if (tb[IFLA_LINKMODE])
                 dev->link_mode = nla_get_u8(tb[IFLA_LINKMODE]);
+        if (tb[IFLA_GROUP])
+                dev_set_group(dev, nla_get_u32(tb[IFLA_GROUP]));
 
         return dev;
 
@@ -1606,10 +1608,6 @@ replay:
         else {
                 if (ifname[0])
                         dev = __dev_get_by_name(net, ifname);
-                else if (tb[IFLA_GROUP])
-                        return rtnl_group_changelink(net,
-                                        nla_get_u32(tb[IFLA_GROUP]),
-                                        ifm, tb);
                 else
                         dev = NULL;
         }
@@ -1676,8 +1674,13 @@ replay:
                         return do_setlink(dev, ifm, tb, ifname, modified);
                 }
 
-                if (!(nlh->nlmsg_flags & NLM_F_CREATE))
+                if (!(nlh->nlmsg_flags & NLM_F_CREATE)) {
+                        if (ifm->ifi_index == 0 && tb[IFLA_GROUP])
+                                return rtnl_group_changelink(net,
+                                                nla_get_u32(tb[IFLA_GROUP]),
+                                                ifm, tb);
                         return -ENODEV;
+                }
 
                 if (ifm->ifi_index)
                         return -EOPNOTSUPP;