netlink: ensure to loop over all netns in genlmsg_multicast_allns()

Nowadays, nlmsg_multicast() returns only 0 or -ESRCH but this was not the
case when commit 134e63756d5f was pushed.
However, there was no reason to stop the loop if a netns does not have
listeners.
Returns -ESRCH only if there was no listeners in all netns.

To avoid having the same problem in the future, I didn't take the
assumption that nlmsg_multicast() returns only 0 or -ESRCH.

Fixes: 134e63756d5f ("genetlink: make netns aware")
CC: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 2 deletions

diff --git a/net/netlink/genetlink.c b/net/netlink/genetlink.c
index d444daf1ac04..6f02499ef007 100644
--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -1081,6 +1081,7 @@ static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
 {
         struct sk_buff *tmp;
         struct net *net, *prev = NULL;
+        bool delivered = false;
         int err;
 
         for_each_net_rcu(net) {
@@ -1092,14 +1093,21 @@ static int genlmsg_mcast(struct sk_buff *skb, u32 portid, unsigned long group,
                         }
                         err = nlmsg_multicast(prev->genl_sock, tmp,
                                               portid, group, flags);
-                        if (err)
+                        if (!err)
+                                delivered = true;
+                        else if (err != -ESRCH)
                                 goto error;
                 }
 
                 prev = net;
         }
 
-        return nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
+        err = nlmsg_multicast(prev->genl_sock, skb, portid, group, flags);
+        if (!err)
+                delivered = true;
+        else if (err != -ESRCH)
+                goto error;
+        return delivered ? 0 : -ESRCH;
  error:
         kfree_skb(skb);
         return err;