ip_tunnel: use a separate struct to store tunnel params in the kernel

Unlike IPv6 tunnels which use purely-kernel __ip6_tnl_parm structure
to store params inside the kernel, IPv4 tunnel code uses the same
ip_tunnel_parm which is being used to talk with the userspace.
This makes it difficult to alter or add any fields or use a
different format for whatever data.
Define struct ip_tunnel_parm_kern, a 1:1 copy of ip_tunnel_parm for
now, and use it throughout the code. Define the pieces, where the copy
user <-> kernel happens, as standalone functions, and copy the data
there field-by-field, so that the kernel-side structure could be easily
modified later on and the users wouldn't have to care about this.

Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 24 insertions, 8 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index e41d30ebaca6..55c7cf9404a4 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -59,7 +59,7 @@ struct ethtool_ops;
 struct kernel_hwtstamp_config;
 struct phy_device;
 struct dsa_port;
-struct ip_tunnel_parm;
+struct ip_tunnel_parm_kern;
 struct macsec_context;
 struct macsec_ops;
 struct netdev_name_node;
@@ -1327,7 +1327,7 @@ struct netdev_net_notifier {
  *	queue id bound to an AF_XDP socket. The flags field specifies if
  *	only RX, only Tx, or both should be woken up using the flags
  *	XDP_WAKEUP_RX and XDP_WAKEUP_TX.
- * int (*ndo_tunnel_ctl)(struct net_device *dev, struct ip_tunnel_parm *p,
+ * int (*ndo_tunnel_ctl)(struct net_device *dev, struct ip_tunnel_parm_kern *p,
  *			 int cmd);
  *	Add, change, delete or get information on an IPv4 tunnel.
  * struct net_device *(*ndo_get_peer_dev)(struct net_device *dev);
@@ -1583,7 +1583,8 @@ struct net_device_ops {
 	int			(*ndo_xsk_wakeup)(struct net_device *dev,
 						  u32 queue_id, u32 flags);
 	int			(*ndo_tunnel_ctl)(struct net_device *dev,
-						  struct ip_tunnel_parm *p, int cmd);
+						  struct ip_tunnel_parm_kern *p,
+						  int cmd);
 	struct net_device *	(*ndo_get_peer_dev)(struct net_device *dev);
 	int                     (*ndo_fill_forward_path)(struct net_device_path_ctx *ctx,
                                                          struct net_device_path *path);
diff --git a/include/net/ip_tunnels.h b/include/net/ip_tunnels.h
index 5cd64bb2104d..20f0319ab149 100644
--- a/include/net/ip_tunnels.h
+++ b/include/net/ip_tunnels.h
@@ -110,6 +110,17 @@ struct ip_tunnel_prl_entry {
 
 struct metadata_dst;
 
+/* Kernel-side copy of ip_tunnel_parm */
+struct ip_tunnel_parm_kern {
+	char			name[IFNAMSIZ];
+	int			link;
+	__be16			i_flags;
+	__be16			o_flags;
+	__be32			i_key;
+	__be32			o_key;
+	struct iphdr		iph;
+};
+
 struct ip_tunnel {
 	struct ip_tunnel __rcu	*next;
 	struct hlist_node hash_node;
@@ -136,7 +147,7 @@ struct ip_tunnel {
 
 	struct dst_cache dst_cache;
 
-	struct ip_tunnel_parm parms;
+	struct ip_tunnel_parm_kern parms;
 
 	int		mlink;
 	int		encap_hlen;	/* Encap header length (FOU,GUE) */
@@ -291,7 +302,11 @@ void ip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 		    const struct iphdr *tnl_params, const u8 protocol);
 void ip_md_tunnel_xmit(struct sk_buff *skb, struct net_device *dev,
 		       const u8 proto, int tunnel_hlen);
-int ip_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm *p, int cmd);
+int ip_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm_kern *p,
+		  int cmd);
+bool ip_tunnel_parm_from_user(struct ip_tunnel_parm_kern *kp,
+			      const void __user *data);
+bool ip_tunnel_parm_to_user(void __user *data, struct ip_tunnel_parm_kern *kp);
 int ip_tunnel_siocdevprivate(struct net_device *dev, struct ifreq *ifr,
 			     void __user *data, int cmd);
 int __ip_tunnel_change_mtu(struct net_device *dev, int new_mtu, bool strict);
@@ -307,16 +322,16 @@ int ip_tunnel_rcv(struct ip_tunnel *tunnel, struct sk_buff *skb,
 		  const struct tnl_ptk_info *tpi, struct metadata_dst *tun_dst,
 		  bool log_ecn_error);
 int ip_tunnel_changelink(struct net_device *dev, struct nlattr *tb[],
-			 struct ip_tunnel_parm *p, __u32 fwmark);
+			 struct ip_tunnel_parm_kern *p, __u32 fwmark);
 int ip_tunnel_newlink(struct net_device *dev, struct nlattr *tb[],
-		      struct ip_tunnel_parm *p, __u32 fwmark);
+		      struct ip_tunnel_parm_kern *p, __u32 fwmark);
 void ip_tunnel_setup(struct net_device *dev, unsigned int net_id);
 
 bool ip_tunnel_netlink_encap_parms(struct nlattr *data[],
 				   struct ip_tunnel_encap *encap);
 
 void ip_tunnel_netlink_parms(struct nlattr *data[],
-			     struct ip_tunnel_parm *parms);
+			     struct ip_tunnel_parm_kern *parms);
 
 extern const struct header_ops ip_tunnel_header_ops;
 __be16 ip_tunnel_parse_protocol(const struct sk_buff *skb);