macvtap/tun: cross-endian support for little-endian hosts

[karo-tx-linux.git] / drivers / net / tun.c

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index b210139bef8f3dbba20f853f33261eff57f7e739..cb376b2d548a1e448f40bf573f819e82dbfc1b43 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -111,6 +111,7 @@ do {                                                                \
 #define TUN_FASYNC     IFF_ATTACH_QUEUE
 /* High bits in flags field are unused. */
 #define TUN_VNET_LE     0x80000000
+#define TUN_VNET_BE     0x40000000
 
 #define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \
                      IFF_MULTI_QUEUE)
@@ -206,10 +207,58 @@ struct tun_struct {
        u32 flow_count;
 };
 
+#ifdef CONFIG_TUN_VNET_CROSS_LE
+static inline bool tun_legacy_is_little_endian(struct tun_struct *tun)
+{
+       return tun->flags & TUN_VNET_BE ? false :
+               virtio_legacy_is_little_endian();
+}
+
+static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)
+{
+       int be = !!(tun->flags & TUN_VNET_BE);
+
+       if (put_user(be, argp))
+               return -EFAULT;
+
+       return 0;
+}
+
+static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)
+{
+       int be;
+
+       if (get_user(be, argp))
+               return -EFAULT;
+
+       if (be)
+               tun->flags |= TUN_VNET_BE;
+       else
+               tun->flags &= ~TUN_VNET_BE;
+
+       return 0;
+}
+#else
+static inline bool tun_legacy_is_little_endian(struct tun_struct *tun)
+{
+       return virtio_legacy_is_little_endian();
+}
+
+static long tun_get_vnet_be(struct tun_struct *tun, int __user *argp)
+{
+       return -EINVAL;
+}
+
+static long tun_set_vnet_be(struct tun_struct *tun, int __user *argp)
+{
+       return -EINVAL;
+}
+#endif /* CONFIG_TUN_VNET_CROSS_LE */
+
 static inline bool tun_is_little_endian(struct tun_struct *tun)
 {
        return tun->flags & TUN_VNET_LE ||
-               virtio_legacy_is_little_endian();
+               tun_legacy_is_little_endian(tun);
 }
 
 static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val)
@@ -2062,6 +2111,14 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
                        tun->flags &= ~TUN_VNET_LE;
                break;
 
+       case TUNGETVNETBE:
+               ret = tun_get_vnet_be(tun, argp);
+               break;
+
+       case TUNSETVNETBE:
+               ret = tun_set_vnet_be(tun, argp);
+               break;
+
        case TUNATTACHFILTER:
                /* Can be set only for TAPs */
                ret = -EINVAL;