[PATCH net 1/2] net/iucv: drop HiperSockets frames from other network namespaces

iucv_packet_type sets neither .dev nor .af_packet_net, so it lands in the
machine-global ptype_base[] that __netif_receive_skb_core walks for every
frame in every namespace, and afiucv_hs_rcv() ignores its dev argument.
An ETH_P_AF_IUCV frame sent from any namespace holding CAP_NET_RAW is
therefore matched against the global iucv_sk_list and can move a socket
owned by the initial namespace: afiucv_hs_callback_synfin() and _fin()
overwrite its sk_state, and _syn() builds an accept-queue child.

Filter on the namespace. The core does not do it for ptype_base[] --
net/core/dev.c leaves namespace filtering to the ptype owner -- and
net/x25/x25_dev.c and net/ieee802154/socket.c both test dev_net(dev) at
exactly this point.

Fixes: 3881ac441f64 ("af_iucv: add HiperSockets transport")
Cc: [email protected]
Signed-off-by: Bryam Vargas <[email protected]>
---
 net/iucv/af_iucv.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index ea047bab65e7..e3ec965d96ca 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -2064,6 +2064,11 @@ static int afiucv_hs_rcv(struct sk_buff *skb, struct net_device *dev,
 	int err = NET_RX_SUCCESS;
 	char nullstring[8];
 
+	if (!net_eq(dev_net(dev), &init_net)) {
+		kfree_skb(skb);
+		return NET_RX_SUCCESS;
+	}
+
 	if (!pskb_may_pull(skb, sizeof(*trans_hdr))) {
 		kfree_skb(skb);
 		return NET_RX_SUCCESS;

-- 
2.55.0