ipv6: lift copy_from_user out of ipv6_route_ioctl

Prepare for better compat ioctl handling by moving the user copy out
of ipv6_route_ioctl.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip6_route.h

@@ -118,7 +118,8 @@ void ip6_route_init_special_entries(void);
 int ip6_route_init(void);
 void ip6_route_cleanup(void);
 
-int ipv6_route_ioctl(struct net *net, unsigned int cmd, void __user *arg);
+int ipv6_route_ioctl(struct net *net, unsigned int cmd,
+		struct in6_rtmsg *rtmsg);
 
 int ip6_route_add(struct fib6_config *cfg, gfp_t gfp_flags,
 		  struct netlink_ext_ack *extack);

net/ipv6/af_inet6.c

@@ -542,21 +542,25 @@ EXPORT_SYMBOL(inet6_getname);
 
 int inet6_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 {
+	void __user *argp = (void __user *)arg;
 	struct sock *sk = sock->sk;
 	struct net *net = sock_net(sk);
 
 	switch (cmd) {
 	case SIOCADDRT:
-	case SIOCDELRT:
-
-		return ipv6_route_ioctl(net, cmd, (void __user *)arg);
+	case SIOCDELRT: {
+		struct in6_rtmsg rtmsg;
 
+		if (copy_from_user(&rtmsg, argp, sizeof(rtmsg)))
+			return -EFAULT;
+		return ipv6_route_ioctl(net, cmd, &rtmsg);
+	}
 	case SIOCSIFADDR:
-		return addrconf_add_ifaddr(net, (void __user *) arg);
+		return addrconf_add_ifaddr(net, argp);
 	case SIOCDIFADDR:
-		return addrconf_del_ifaddr(net, (void __user *) arg);
+		return addrconf_del_ifaddr(net, argp);
 	case SIOCSIFDSTADDR:
-		return addrconf_set_dstaddr(net, (void __user *) arg);
+		return addrconf_set_dstaddr(net, argp);
 	default:
 		if (!sk->sk_prot->ioctl)
 			return -ENOIOCTLCMD;

net/ipv6/route.c

@@ -4336,41 +4336,29 @@ static void rtmsg_to_fib6_config(struct net *net,
 	};
 }
 
-int ipv6_route_ioctl(struct net *net, unsigned int cmd, void __user *arg)
+int ipv6_route_ioctl(struct net *net, unsigned int cmd, struct in6_rtmsg *rtmsg)
 {
 	struct fib6_config cfg;
-	struct in6_rtmsg rtmsg;
 	int err;
 
-	switch (cmd) {
-	case SIOCADDRT:		/* Add a route */
-	case SIOCDELRT:		/* Delete a route */
-		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
-			return -EPERM;
-		err = copy_from_user(&rtmsg, arg,
-				     sizeof(struct in6_rtmsg));
-		if (err)
-			return -EFAULT;
+	if (cmd != SIOCADDRT && cmd != SIOCDELRT)
+		return -EINVAL;
+	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
+		return -EPERM;
 
-		rtmsg_to_fib6_config(net, &rtmsg, &cfg);
+	rtmsg_to_fib6_config(net, rtmsg, &cfg);
 
-		rtnl_lock();
-		switch (cmd) {
-		case SIOCADDRT:
-			err = ip6_route_add(&cfg, GFP_KERNEL, NULL);
-			break;
-		case SIOCDELRT:
-			err = ip6_route_del(&cfg, NULL);
-			break;
-		default:
-			err = -EINVAL;
-		}
-		rtnl_unlock();
-
-		return err;
+	rtnl_lock();
+	switch (cmd) {
+	case SIOCADDRT:
+		err = ip6_route_add(&cfg, GFP_KERNEL, NULL);
+		break;
+	case SIOCDELRT:
+		err = ip6_route_del(&cfg, NULL);
+		break;
 	}
-
-	return -EINVAL;
+	rtnl_unlock();
+	return err;
 }
 
 /*