[PATCH 4.4 24/36] netlink: ensure to loop over all netns in genlmsg_multicast_allns()

Greg Kroah-Hartman
2018-03-10T00:20:54Z

From: Nicolas Dichtel <nicolas.dichtel@6wind.com>

[ Upstream commit cb9f7a9a5c96a773bbc9c70660dc600cfff82f82 ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/netlink/genetlink.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

--- a/net/netlink/genetlink.c
+++ b/net/netlink/genetlink.c
@@ -1118,6 +1118,7 @@ static int genlmsg_mcast(struct sk_buff
{
struct sk_buff *tmp;
struct net *net, *prev = NULL;
+ bool delivered = false;
int err;

for_each_net_rcu(net) {
@@ -1129,14 +1130,21 @@ static int genlmsg_mcast(struct sk_buff
}
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;