bareudp: Pull inner IP header on xmit.

JIRA: https://issues.redhat.com/browse/RHEL-59593
Upstream Status: linux.git

commit c471236
Author: Guillaume Nault <gnault@redhat.com>
Date:   Wed Sep 11 11:21:05 2024 +0200

    bareudp: Pull inner IP header on xmit.

    Both bareudp_xmit_skb() and bareudp6_xmit_skb() read their skb's inner
    IP header to get its ECN value (with ip_tunnel_ecn_encap()). Therefore
    we need to ensure that the inner IP header is part of the skb's linear
    data.

    Fixes: 571912c ("net: UDP tunnel encapsulation module for tunnelling different protocols like MPLS, IP, NSH etc.")
    Signed-off-by: Guillaume Nault <gnault@redhat.com>
    Reviewed-by: Willem de Bruijn <willemb@google.com>
    Link: https://patch.msgid.link/267328222f0a11519c6de04c640a4f87a38ea9ed.1726046181.git.gnault@redhat.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Guillaume Nault <gnault@redhat.com>

Author: Guillaume Nault

drivers/net/bareudp.c

@@ -323,6 +323,9 @@ static int bareudp_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 	__be32 saddr;
 	int err;
 
+	if (!skb_vlan_inet_prepare(skb, skb->protocol != htons(ETH_P_TEB)))
+		return -EINVAL;
+
 	if (!sock)
 		return -ESHUTDOWN;
 
@@ -390,6 +393,9 @@ static int bareudp6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 	__be16 sport;
 	int err;
 
+	if (!skb_vlan_inet_prepare(skb, skb->protocol != htons(ETH_P_TEB)))
+		return -EINVAL;
+
 	if (!sock)
 		return -ESHUTDOWN;