netlink/genetlink: pass network namespace to bind/unbind

Netlink families can exist in multiple namespaces, and for the most
part multicast subscriptions are per network namespace. Thus it only
makes sense to have bind/unbind notifications per network namespace.

To achieve this, pass the network namespace of a given client socket
to the bind/unbind functions.

Also do this in generic netlink, and there also make sure that any
bind for multicast groups that only exist in init_net is rejected.
This isn't really a problem if it is accepted since a client in a
different namespace will never receive any notifications from such
a group, but it can confuse the family if not rejected (it's also
possible to silently (without telling the family) accept it, but it
would also have to be ignored on unbind so families that take any
kind of action on bind/unbind won't do unnecessary work for invalid
clients like that.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 5 deletions

diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index 05bf40bbd189..91566ed36c43 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -983,7 +983,7 @@ static struct genl_multicast_group genl_ctrl_groups[] = {
         { .name = "notify", },
 };
 
-static int genl_bind(int group)
+static int genl_bind(struct net *net, int group)
 {
         int i, err;
         bool found = false;
@@ -997,8 +997,10 @@ static int genl_bind(int group)
                             group < f->mcgrp_offset + f->n_mcgrps) {
                                 int fam_grp = group - f->mcgrp_offset;
 
-                                if (f->mcast_bind)
-                                        err = f->mcast_bind(fam_grp);
+                                if (!f->netnsok && net != &init_net)
+                                        err = -ENOENT;
+                                else if (f->mcast_bind)
+                                        err = f->mcast_bind(net, fam_grp);
                                 else
                                         err = 0;
                                 found = true;
@@ -1014,7 +1016,7 @@ static int genl_bind(int group)
         return err;
 }
 
-static void genl_unbind(int group)
+static void genl_unbind(struct net *net, int group)
 {
         int i;
         bool found = false;
@@ -1029,7 +1031,7 @@ static void genl_unbind(int group)
                                 int fam_grp = group - f->mcgrp_offset;
 
                                 if (f->mcast_unbind)
-                                        f->mcast_unbind(fam_grp);
+                                        f->mcast_unbind(net, fam_grp);
                                 found = true;
                                 break;
                         }