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>

6 files changed, 73 insertions, 35 deletions

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 7b16c211b904..8853c065a985 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -785,7 +785,8 @@ static void ipgre_link_update(struct net_device *dev, bool set_mtu)
 	}
 }
 
-static int ipgre_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm *p,
+static int ipgre_tunnel_ctl(struct net_device *dev,
+			    struct ip_tunnel_parm_kern *p,
 			    int cmd)
 {
 	int err;
@@ -1131,7 +1132,7 @@ static int erspan_validate(struct nlattr *tb[], struct nlattr *data[],
 static int ipgre_netlink_parms(struct net_device *dev,
 				struct nlattr *data[],
 				struct nlattr *tb[],
-				struct ip_tunnel_parm *parms,
+				struct ip_tunnel_parm_kern *parms,
 				__u32 *fwmark)
 {
 	struct ip_tunnel *t = netdev_priv(dev);
@@ -1198,7 +1199,7 @@ static int ipgre_netlink_parms(struct net_device *dev,
 static int erspan_netlink_parms(struct net_device *dev,
 				struct nlattr *data[],
 				struct nlattr *tb[],
-				struct ip_tunnel_parm *parms,
+				struct ip_tunnel_parm_kern *parms,
 				__u32 *fwmark)
 {
 	struct ip_tunnel *t = netdev_priv(dev);
@@ -1357,7 +1358,7 @@ static int ipgre_newlink(struct net *src_net, struct net_device *dev,
 			 struct nlattr *tb[], struct nlattr *data[],
 			 struct netlink_ext_ack *extack)
 {
-	struct ip_tunnel_parm p;
+	struct ip_tunnel_parm_kern p;
 	__u32 fwmark = 0;
 	int err;
 
@@ -1375,7 +1376,7 @@ static int erspan_newlink(struct net *src_net, struct net_device *dev,
 			  struct nlattr *tb[], struct nlattr *data[],
 			  struct netlink_ext_ack *extack)
 {
-	struct ip_tunnel_parm p;
+	struct ip_tunnel_parm_kern p;
 	__u32 fwmark = 0;
 	int err;
 
@@ -1394,8 +1395,8 @@ static int ipgre_changelink(struct net_device *dev, struct nlattr *tb[],
 			    struct netlink_ext_ack *extack)
 {
 	struct ip_tunnel *t = netdev_priv(dev);
+	struct ip_tunnel_parm_kern p;
 	__u32 fwmark = t->fwmark;
-	struct ip_tunnel_parm p;
 	int err;
 
 	err = ipgre_newlink_encap_setup(dev, data);
@@ -1423,8 +1424,8 @@ static int erspan_changelink(struct net_device *dev, struct nlattr *tb[],
 			     struct netlink_ext_ack *extack)
 {
 	struct ip_tunnel *t = netdev_priv(dev);
+	struct ip_tunnel_parm_kern p;
 	__u32 fwmark = t->fwmark;
-	struct ip_tunnel_parm p;
 	int err;
 
 	err = ipgre_newlink_encap_setup(dev, data);
@@ -1496,7 +1497,7 @@ static size_t ipgre_get_size(const struct net_device *dev)
 static int ipgre_fill_info(struct sk_buff *skb, const struct net_device *dev)
 {
 	struct ip_tunnel *t = netdev_priv(dev);
-	struct ip_tunnel_parm *p = &t->parms;
+	struct ip_tunnel_parm_kern *p = &t->parms;
 	__be16 o_flags = p->o_flags;
 
 	if (nla_put_u32(skb, IFLA_GRE_LINK, p->link) ||
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);
diff --git a/net/ipv4/ip_tunnel_core.c b/net/ipv4/ip_tunnel_core.c
index 80ccd6661aa3..98f136b07191 100644
--- a/net/ipv4/ip_tunnel_core.c
+++ b/net/ipv4/ip_tunnel_core.c
@@ -1116,7 +1116,7 @@ bool ip_tunnel_netlink_encap_parms(struct nlattr *data[],
 EXPORT_SYMBOL_GPL(ip_tunnel_netlink_encap_parms);
 
 void ip_tunnel_netlink_parms(struct nlattr *data[],
-			     struct ip_tunnel_parm *parms)
+			     struct ip_tunnel_parm_kern *parms)
 {
 	if (data[IFLA_IPTUN_LINK])
 		parms->link = nla_get_u32(data[IFLA_IPTUN_LINK]);
diff --git a/net/ipv4/ip_vti.c b/net/ipv4/ip_vti.c
index ee587adb169f..7e595f619615 100644
--- a/net/ipv4/ip_vti.c
+++ b/net/ipv4/ip_vti.c
@@ -167,7 +167,7 @@ static netdev_tx_t vti_xmit(struct sk_buff *skb, struct net_device *dev,
 			    struct flowi *fl)
 {
 	struct ip_tunnel *tunnel = netdev_priv(dev);
-	struct ip_tunnel_parm *parms = &tunnel->parms;
+	struct ip_tunnel_parm_kern *parms = &tunnel->parms;
 	struct dst_entry *dst = skb_dst(skb);
 	struct net_device *tdev;	/* Device to other host */
 	int pkt_len = skb->len;
@@ -373,7 +373,7 @@ static int vti4_err(struct sk_buff *skb, u32 info)
 }
 
 static int
-vti_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm *p, int cmd)
+vti_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm_kern *p, int cmd)
 {
 	int err = 0;
 
@@ -531,7 +531,7 @@ static int vti_tunnel_validate(struct nlattr *tb[], struct nlattr *data[],
 }
 
 static void vti_netlink_parms(struct nlattr *data[],
-			      struct ip_tunnel_parm *parms,
+			      struct ip_tunnel_parm_kern *parms,
 			      __u32 *fwmark)
 {
 	memset(parms, 0, sizeof(*parms));
@@ -566,7 +566,7 @@ static int vti_newlink(struct net *src_net, struct net_device *dev,
 		       struct nlattr *tb[], struct nlattr *data[],
 		       struct netlink_ext_ack *extack)
 {
-	struct ip_tunnel_parm parms;
+	struct ip_tunnel_parm_kern parms;
 	__u32 fwmark = 0;
 
 	vti_netlink_parms(data, &parms, &fwmark);
@@ -578,8 +578,8 @@ static int vti_changelink(struct net_device *dev, struct nlattr *tb[],
 			  struct netlink_ext_ack *extack)
 {
 	struct ip_tunnel *t = netdev_priv(dev);
+	struct ip_tunnel_parm_kern p;
 	__u32 fwmark = t->fwmark;
-	struct ip_tunnel_parm p;
 
 	vti_netlink_parms(data, &p, &fwmark);
 	return ip_tunnel_changelink(dev, tb, &p, fwmark);
@@ -606,7 +606,7 @@ static size_t vti_get_size(const struct net_device *dev)
 static int vti_fill_info(struct sk_buff *skb, const struct net_device *dev)
 {
 	struct ip_tunnel *t = netdev_priv(dev);
-	struct ip_tunnel_parm *p = &t->parms;
+	struct ip_tunnel_parm_kern *p = &t->parms;
 
 	if (nla_put_u32(skb, IFLA_VTI_LINK, p->link) ||
 	    nla_put_be32(skb, IFLA_VTI_IKEY, p->i_key) ||
diff --git a/net/ipv4/ipip.c b/net/ipv4/ipip.c
index f2696eaadbe6..db960cd08a3b 100644
--- a/net/ipv4/ipip.c
+++ b/net/ipv4/ipip.c
@@ -330,7 +330,7 @@ static bool ipip_tunnel_ioctl_verify_protocol(u8 ipproto)
 }
 
 static int
-ipip_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm *p, int cmd)
+ipip_tunnel_ctl(struct net_device *dev, struct ip_tunnel_parm_kern *p, int cmd)
 {
 	if (cmd == SIOCADDTUNNEL || cmd == SIOCCHGTUNNEL) {
 		if (p->iph.version != 4 ||
@@ -405,8 +405,8 @@ static int ipip_tunnel_validate(struct nlattr *tb[], struct nlattr *data[],
 }
 
 static void ipip_netlink_parms(struct nlattr *data[],
-			       struct ip_tunnel_parm *parms, bool *collect_md,
-			       __u32 *fwmark)
+			       struct ip_tunnel_parm_kern *parms,
+			       bool *collect_md, __u32 *fwmark)
 {
 	memset(parms, 0, sizeof(*parms));
 
@@ -432,8 +432,8 @@ static int ipip_newlink(struct net *src_net, struct net_device *dev,
 			struct netlink_ext_ack *extack)
 {
 	struct ip_tunnel *t = netdev_priv(dev);
-	struct ip_tunnel_parm p;
 	struct ip_tunnel_encap ipencap;
+	struct ip_tunnel_parm_kern p;
 	__u32 fwmark = 0;
 
 	if (ip_tunnel_netlink_encap_parms(data, &ipencap)) {
@@ -452,8 +452,8 @@ static int ipip_changelink(struct net_device *dev, struct nlattr *tb[],
 			   struct netlink_ext_ack *extack)
 {
 	struct ip_tunnel *t = netdev_priv(dev);
-	struct ip_tunnel_parm p;
 	struct ip_tunnel_encap ipencap;
+	struct ip_tunnel_parm_kern p;
 	bool collect_md;
 	__u32 fwmark = t->fwmark;
 
@@ -510,7 +510,7 @@ static size_t ipip_get_size(const struct net_device *dev)
 static int ipip_fill_info(struct sk_buff *skb, const struct net_device *dev)
 {
 	struct ip_tunnel *tunnel = netdev_priv(dev);
-	struct ip_tunnel_parm *parm = &tunnel->parms;
+	struct ip_tunnel_parm_kern *parm = &tunnel->parms;
 
 	if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) ||
 	    nla_put_in_addr(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) ||
diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c
index fd5c01c8489f..6c750bd13dd8 100644
--- a/net/ipv4/ipmr.c
+++ b/net/ipv4/ipmr.c
@@ -441,7 +441,7 @@ static bool ipmr_init_vif_indev(const struct net_device *dev)
 static struct net_device *ipmr_new_tunnel(struct net *net, struct vifctl *v)
 {
 	struct net_device *tunnel_dev, *new_dev;
-	struct ip_tunnel_parm p = { };
+	struct ip_tunnel_parm_kern p = { };
 	int err;
 
 	tunnel_dev = __dev_get_by_name(net, "tunl0");