@@ -351,6 +351,127 @@ static inline __virtio16 cpu_to_tun16(unsigned int flags, u16 val)
 	return __cpu_to_virtio16(tun_is_little_endian(flags), val);
 }
 
+static long tun_vnet_ioctl(int *vnet_hdr_sz, unsigned int *flags,
+			   unsigned int cmd, int __user *sp)
+{
+	int s;
+
+	switch (cmd) {
+	case TUNGETVNETHDRSZ:
+		s = *vnet_hdr_sz;
+		if (put_user(s, sp))
+			return -EFAULT;
+		return 0;
+
+	case TUNSETVNETHDRSZ:
+		if (get_user(s, sp))
+			return -EFAULT;
+		if (s < (int)sizeof(struct virtio_net_hdr))
+			return -EINVAL;
+
+		*vnet_hdr_sz = s;
+		return 0;
+
+	case TUNGETVNETLE:
+		s = !!(*flags & TUN_VNET_LE);
+		if (put_user(s, sp))
+			return -EFAULT;
+		return 0;
+
+	case TUNSETVNETLE:
+		if (get_user(s, sp))
+			return -EFAULT;
+		if (s)
+			*flags |= TUN_VNET_LE;
+		else
+			*flags &= ~TUN_VNET_LE;
+		return 0;
+
+	case TUNGETVNETBE:
+		return tun_get_vnet_be(*flags, sp);
+
+	case TUNSETVNETBE:
+		return tun_set_vnet_be(flags, sp);
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int tun_vnet_hdr_get(int sz, unsigned int flags, struct iov_iter *from,
+			    struct virtio_net_hdr *hdr)
+{
+	u16 hdr_len;
+
+	if (iov_iter_count(from) < sz)
+		return -EINVAL;
+
+	if (!copy_from_iter_full(hdr, sizeof(*hdr), from))
+		return -EFAULT;
+
+	hdr_len = tun16_to_cpu(flags, hdr->hdr_len);
+
+	if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
+		hdr_len = max(tun16_to_cpu(flags, hdr->csum_start) + tun16_to_cpu(flags, hdr->csum_offset) + 2, hdr_len);
+		hdr->hdr_len = cpu_to_tun16(flags, hdr_len);
+	}
+
+	if (hdr_len > iov_iter_count(from))
+		return -EINVAL;
+
+	iov_iter_advance(from, sz - sizeof(*hdr));
+
+	return hdr_len;
+}
+
+static int tun_vnet_hdr_put(int sz, struct iov_iter *iter,
+			    const struct virtio_net_hdr *hdr)
+{
+	if (unlikely(iov_iter_count(iter) < sz))
+		return -EINVAL;
+
+	if (unlikely(copy_to_iter(hdr, sizeof(*hdr), iter) != sizeof(*hdr)))
+		return -EFAULT;
+
+	iov_iter_advance(iter, sz - sizeof(*hdr));
+
+	return 0;
+}
+
+static int tun_vnet_hdr_to_skb(unsigned int flags, struct sk_buff *skb,
+			       const struct virtio_net_hdr *hdr)
+{
+	return virtio_net_hdr_to_skb(skb, hdr, tun_is_little_endian(flags));
+}
+
+static int tun_vnet_hdr_from_skb(unsigned int flags,
+				 const struct net_device *dev,
+				 const struct sk_buff *skb,
+				 struct virtio_net_hdr *hdr)
+{
+	int vlan_hlen = skb_vlan_tag_present(skb) ? VLAN_HLEN : 0;
+
+	if (virtio_net_hdr_from_skb(skb, hdr,
+				    tun_is_little_endian(flags), true,
+				    vlan_hlen)) {
+		struct skb_shared_info *sinfo = skb_shinfo(skb);
+
+		if (net_ratelimit()) {
+			netdev_err(dev, "unexpected GSO type: 0x%x, gso_size %d, hdr_len %d\n",
+				   sinfo->gso_type, tun16_to_cpu(flags, hdr->gso_size),
+				   tun16_to_cpu(flags, hdr->hdr_len));
+			print_hex_dump(KERN_ERR, "tun: ",
+				       DUMP_PREFIX_NONE,
+				       16, 1, skb->head,
+				       min(tun16_to_cpu(flags, hdr->hdr_len), 64), true);
+		}
+		WARN_ON_ONCE(1);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static inline u32 tun_hashfn(u32 rxhash)
 {
 	return rxhash & TUN_MASK_FLOW_ENTRIES;

@@ -1764,25 +1885,12 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 
 	if (tun->flags & IFF_VNET_HDR) {
 		int vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz);
-		int flags = tun->flags;
-
-		if (len < vnet_hdr_sz)
-			return -EINVAL;
-		len -= vnet_hdr_sz;
-
-		if (!copy_from_iter_full(&gso, sizeof(gso), from))
-			return -EFAULT;
-
-		hdr_len = tun16_to_cpu(flags, gso.hdr_len);
 
-		if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
-			hdr_len = max(tun16_to_cpu(flags, gso.csum_start) + tun16_to_cpu(flags, gso.csum_offset) + 2, hdr_len);
-			gso.hdr_len = cpu_to_tun16(flags, hdr_len);
-		}
+		hdr_len = tun_vnet_hdr_get(vnet_hdr_sz, tun->flags, from, &gso);
+		if (hdr_len < 0)
+			return hdr_len;
 
-		if (hdr_len > len)
-			return -EINVAL;
-		iov_iter_advance(from, vnet_hdr_sz - sizeof(gso));
+		len -= vnet_hdr_sz;
 	}
 
 	if ((tun->flags & TUN_TYPE_MASK) == IFF_TAP) {

@@ -1856,7 +1964,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 		}
 	}
 
-	if (virtio_net_hdr_to_skb(skb, &gso, tun_is_little_endian(tun->flags))) {
+	if (tun_vnet_hdr_to_skb(tun->flags, skb, &gso)) {
 		atomic_long_inc(&tun->rx_frame_errors);
 		err = -EINVAL;
 		goto free_skb;

@@ -2051,18 +2159,15 @@ static ssize_t tun_put_user_xdp(struct tun_struct *tun,
 {
 	int vnet_hdr_sz = 0;
 	size_t size = xdp_frame->len;
-	size_t ret;
+	ssize_t ret;
 
 	if (tun->flags & IFF_VNET_HDR) {
 		struct virtio_net_hdr gso = { 0 };
 
 		vnet_hdr_sz = READ_ONCE(tun->vnet_hdr_sz);
-		if (unlikely(iov_iter_count(iter) < vnet_hdr_sz))
-			return -EINVAL;
-		if (unlikely(copy_to_iter(&gso, sizeof(gso), iter) !=
-			     sizeof(gso)))
-			return -EFAULT;
-		iov_iter_advance(iter, vnet_hdr_sz - sizeof(gso));
+		ret = tun_vnet_hdr_put(vnet_hdr_sz, iter, &gso);
+		if (ret)
+			return ret;
 	}
 
 	ret = copy_to_iter(xdp_frame->data, size, iter) + vnet_hdr_sz;

@@ -2085,6 +2190,7 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 	int vlan_offset = 0;
 	int vlan_hlen = 0;
 	int vnet_hdr_sz = 0;
+	int ret;
 
 	if (skb_vlan_tag_present(skb))
 		vlan_hlen = VLAN_HLEN;

@@ -2110,33 +2216,14 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 
 	if (vnet_hdr_sz) {
 		struct virtio_net_hdr gso;
-		int flags = tun->flags;
-
-		if (iov_iter_count(iter) < vnet_hdr_sz)
-			return -EINVAL;
-
-		if (virtio_net_hdr_from_skb(skb, &gso,
-					    tun_is_little_endian(flags), true,
-					    vlan_hlen)) {
-			struct skb_shared_info *sinfo = skb_shinfo(skb);
-
-			if (net_ratelimit()) {
-				netdev_err(tun->dev, "unexpected GSO type: 0x%x, gso_size %d, hdr_len %d\n",
-					   sinfo->gso_type, tun16_to_cpu(flags, gso.gso_size),
-					   tun16_to_cpu(flags, gso.hdr_len));
-				print_hex_dump(KERN_ERR, "tun: ",
-					       DUMP_PREFIX_NONE,
-					       16, 1, skb->head,
-					       min((int)tun16_to_cpu(flags, gso.hdr_len), 64), true);
-			}
-			WARN_ON_ONCE(1);
-			return -EINVAL;
-		}
 
-		if (copy_to_iter(&gso, sizeof(gso), iter) != sizeof(gso))
-			return -EFAULT;
+		ret = tun_vnet_hdr_from_skb(tun->flags, tun->dev, skb, &gso);
+		if (ret)
+			return ret;
 
-		iov_iter_advance(iter, vnet_hdr_sz - sizeof(gso));
+		ret = tun_vnet_hdr_put(vnet_hdr_sz, iter, &gso);
+		if (ret)
+			return ret;
 	}
 
 	if (vlan_hlen) {

@@ -2496,7 +2583,7 @@ static int tun_xdp_one(struct tun_struct *tun,
 	skb_reserve(skb, xdp->data - xdp->data_hard_start);
 	skb_put(skb, xdp->data_end - xdp->data);
 
-	if (virtio_net_hdr_to_skb(skb, gso, tun_is_little_endian(tun->flags))) {
+	if (tun_vnet_hdr_to_skb(tun->flags, skb, gso)) {
 		atomic_long_inc(&tun->rx_frame_errors);
 		kfree_skb(skb);
 		ret = -EINVAL;

@@ -3080,8 +3167,6 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
 	kgid_t group;
 	int ifindex;
 	int sndbuf;
-	int vnet_hdr_sz;
-	int le;
 	int ret;
 	bool do_notify = false;
 

@@ -3288,50 +3373,6 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
 		tun_set_sndbuf(tun);
 		break;
 
-	case TUNGETVNETHDRSZ:
-		vnet_hdr_sz = tun->vnet_hdr_sz;
-		if (copy_to_user(argp, &vnet_hdr_sz, sizeof(vnet_hdr_sz)))
-			ret = -EFAULT;
-		break;
-
-	case TUNSETVNETHDRSZ:
-		if (copy_from_user(&vnet_hdr_sz, argp, sizeof(vnet_hdr_sz))) {
-			ret = -EFAULT;
-			break;
-		}
-		if (vnet_hdr_sz < (int)sizeof(struct virtio_net_hdr)) {
-			ret = -EINVAL;
-			break;
-		}
-
-		tun->vnet_hdr_sz = vnet_hdr_sz;
-		break;
-
-	case TUNGETVNETLE:
-		le = !!(tun->flags & TUN_VNET_LE);
-		if (put_user(le, (int __user *)argp))
-			ret = -EFAULT;
-		break;
-
-	case TUNSETVNETLE:
-		if (get_user(le, (int __user *)argp)) {
-			ret = -EFAULT;
-			break;
-		}
-		if (le)
-			tun->flags |= TUN_VNET_LE;
-		else
-			tun->flags &= ~TUN_VNET_LE;
-		break;
-
-	case TUNGETVNETBE:
-		ret = tun_get_vnet_be(tun->flags, argp);
-		break;
-
-	case TUNSETVNETBE:
-		ret = tun_set_vnet_be(&tun->flags, argp);
-		break;
-
 	case TUNATTACHFILTER:
 		/* Can be set only for TAPs */
 		ret = -EINVAL;

@@ -3387,7 +3428,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
 		break;
 
 	default:
-		ret = -EINVAL;
+		ret = tun_vnet_ioctl(&tun->vnet_hdr_sz, &tun->flags, cmd, argp);
 		break;
 	}