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>

1 files changed, 50 insertions, 13 deletions

diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c
index 1b8d8ff9a237..d10f41f81463 100644
--- a/net/ipv4/ip_tunnel.c
+++ b/net/ipv4/ip_tunnel.c
@@ -56,7 +56,7 @@ static unsigned int ip_tunnel_hash(__be32 key, __be32 remote)
 			 IP_TNL_HASH_BITS);
 }
 
-static bool ip_tunnel_key_match(const struct ip_tunnel_parm *p,
+static bool ip_tunnel_key_match(const struct ip_tunnel_parm_kern *p,
 				__be16 flags, __be32 key)
 {
 	if (p->i_flags & TUNNEL_KEY) {
@@ -171,7 +171,7 @@ struct ip_tunnel *ip_tunnel_lookup(struct ip_tunnel_net *itn,
 EXPORT_SYMBOL_GPL(ip_tunnel_lookup);
 
 static struct hlist_head *ip_bucket(struct ip_tunnel_net *itn,
-				    struct ip_tunnel_parm *parms)
+				    struct ip_tunnel_parm_kern *parms)
 {
 	unsigned int h;
 	__be32 remote;
@@ -206,7 +206,7 @@ static void ip_tunnel_del(struct ip_tunnel_net *itn, struct ip_tunnel *t)
 }
 
 static struct ip_tunnel *ip_tunnel_find(struct ip_tunnel_net *itn,
-					struct ip_tunnel_parm *parms,
+					struct ip_tunnel_parm_kern *parms,
 					int type)
 {
 	__be32 remote = parms->iph.daddr;
@@ -230,7 +230,7 @@ static struct ip_tunnel *ip_tunnel_find(struct ip_tunnel_net *itn,
 
 static struct net_device *__ip_tunnel_create(struct net *net,
 					     const struct rtnl_link_ops *ops,
-					     struct ip_tunnel_parm *parms)
+					     struct ip_tunnel_parm_kern *parms)
 {
 	int err;
 	struct ip_tunnel *tunnel;
@@ -326,7 +326,7 @@ static int ip_tunnel_bind_dev(struct net_device *dev)
 
 static struct ip_tunnel *ip_tunnel_create(struct net *net,
 					  struct ip_tunnel_net *itn,
-					  struct ip_tunnel_parm *parms)
+					  struct ip_tunnel_parm_kern *parms)
 {
 	struct ip_tunnel *nt;
 	struct net_device *dev;
@@ -871,7 +871,7 @@ EXPORT_SYMBOL_GPL(ip_tunnel_xmit);
 static void ip_tunnel_update(struct ip_tunnel_net *itn,
 			     struct ip_tunnel *t,
 			     struct net_device *dev,
-			     struct ip_tunnel_parm *p,
+			     struct ip_tunnel_parm_kern *p,
 			     bool set_mtu,
 			     __u32 fwmark)
 {
@@ -903,7 +903,8 @@ static void ip_tunnel_update(struct ip_tunnel_net *itn,
 	netdev_state_change(dev);
 }
 
-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)
 {
 	int err = 0;
 	struct ip_tunnel *t = netdev_priv(dev);
@@ -1005,16 +1006,52 @@ done:
 }
 EXPORT_SYMBOL_GPL(ip_tunnel_ctl);
 
+bool ip_tunnel_parm_from_user(struct ip_tunnel_parm_kern *kp,
+			      const void __user *data)
+{
+	struct ip_tunnel_parm p;
+
+	if (copy_from_user(&p, data, sizeof(p)))
+		return false;
+
+	strscpy(kp->name, p.name);
+	kp->link = p.link;
+	kp->i_flags = p.i_flags;
+	kp->o_flags = p.o_flags;
+	kp->i_key = p.i_key;
+	kp->o_key = p.o_key;
+	memcpy(&kp->iph, &p.iph, min(sizeof(kp->iph), sizeof(p.iph)));
+
+	return true;
+}
+EXPORT_SYMBOL_GPL(ip_tunnel_parm_from_user);
+
+bool ip_tunnel_parm_to_user(void __user *data, struct ip_tunnel_parm_kern *kp)
+{
+	struct ip_tunnel_parm p;
+
+	strscpy(p.name, kp->name);
+	p.link = kp->link;
+	p.i_flags = kp->i_flags;
+	p.o_flags = kp->o_flags;
+	p.i_key = kp->i_key;
+	p.o_key = kp->o_key;
+	memcpy(&p.iph, &kp->iph, min(sizeof(p.iph), sizeof(kp->iph)));
+
+	return !copy_to_user(data, &p, sizeof(p));
+}
+EXPORT_SYMBOL_GPL(ip_tunnel_parm_to_user);
+
 int ip_tunnel_siocdevprivate(struct net_device *dev, struct ifreq *ifr,
 			     void __user *data, int cmd)
 {
-	struct ip_tunnel_parm p;
+	struct ip_tunnel_parm_kern p;
 	int err;
 
-	if (copy_from_user(&p, data, sizeof(p)))
+	if (!ip_tunnel_parm_from_user(&p, data))
 		return -EFAULT;
 	err = dev->netdev_ops->ndo_tunnel_ctl(dev, &p, cmd);
-	if (!err && copy_to_user(data, &p, sizeof(p)))
+	if (!err && !ip_tunnel_parm_to_user(data, &p))
 		return -EFAULT;
 	return err;
 }
@@ -1093,7 +1130,7 @@ int ip_tunnel_init_net(struct net *net, unsigned int ip_tnl_net_id,
 				  struct rtnl_link_ops *ops, char *devname)
 {
 	struct ip_tunnel_net *itn = net_generic(net, ip_tnl_net_id);
-	struct ip_tunnel_parm parms;
+	struct ip_tunnel_parm_kern parms;
 	unsigned int i;
 
 	itn->rtnl_link_ops = ops;
@@ -1171,7 +1208,7 @@ void ip_tunnel_delete_nets(struct list_head *net_list, unsigned int id,
 EXPORT_SYMBOL_GPL(ip_tunnel_delete_nets);
 
 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)
 {
 	struct ip_tunnel *nt;
 	struct net *net = dev_net(dev);
@@ -1225,7 +1262,7 @@ err_register_netdevice:
 EXPORT_SYMBOL_GPL(ip_tunnel_newlink);
 
 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)
 {
 	struct ip_tunnel *t;
 	struct ip_tunnel *tunnel = netdev_priv(dev);