tun: TUN_VNET_LE support, fix sparse warnings for virtio headers

Pretty straight-forward: convert all fields to/from
virtio endian-ness.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Jason Wang <jasowang@redhat.com>

drivers/net/tun.c

@@ -111,7 +111,7 @@ do {								\
 #define TUN_FASYNC	IFF_ATTACH_QUEUE
 
 #define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \
-		      IFF_MULTI_QUEUE)
+		      IFF_VNET_LE | IFF_MULTI_QUEUE)
 #define GOODCOPY_LEN 128
 
 #define FLT_EXACT_COUNT 8
@@ -205,6 +205,16 @@ struct tun_struct {
 	u32 flow_count;
 };
 
+static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val)
+{
+	return __virtio16_to_cpu(tun->flags & IFF_VNET_LE, val);
+}
+
+static inline __virtio16 cpu_to_tun16(struct tun_struct *tun, u16 val)
+{
+	return __cpu_to_virtio16(tun->flags & IFF_VNET_LE, val);
+}
+
 static inline u32 tun_hashfn(u32 rxhash)
 {
 	return rxhash & 0x3ff;
@@ -1053,10 +1063,10 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 			return -EFAULT;
 
 		if ((gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
-		    gso.csum_start + gso.csum_offset + 2 > gso.hdr_len)
-			gso.hdr_len = gso.csum_start + gso.csum_offset + 2;
+		    tun16_to_cpu(tun, gso.csum_start) + tun16_to_cpu(tun, gso.csum_offset) + 2 > tun16_to_cpu(tun, gso.hdr_len))
+			gso.hdr_len = cpu_to_tun16(tun, tun16_to_cpu(tun, gso.csum_start) + tun16_to_cpu(tun, gso.csum_offset) + 2);
 
-		if (gso.hdr_len > len)
+		if (tun16_to_cpu(tun, gso.hdr_len) > len)
 			return -EINVAL;
 		offset += tun->vnet_hdr_sz;
 	}
@@ -1064,7 +1074,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 	if ((tun->flags & TUN_TYPE_MASK) == IFF_TAP) {
 		align += NET_IP_ALIGN;
 		if (unlikely(len < ETH_HLEN ||
-			     (gso.hdr_len && gso.hdr_len < ETH_HLEN)))
+			     (gso.hdr_len && tun16_to_cpu(tun, gso.hdr_len) < ETH_HLEN)))
 			return -EINVAL;
 	}
 
@@ -1075,7 +1085,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 		 * enough room for skb expand head in case it is used.
 		 * The rest of the buffer is mapped from userspace.
 		 */
-		copylen = gso.hdr_len ? gso.hdr_len : GOODCOPY_LEN;
+		copylen = gso.hdr_len ? tun16_to_cpu(tun, gso.hdr_len) : GOODCOPY_LEN;
 		if (copylen > good_linear)
 			copylen = good_linear;
 		linear = copylen;
@@ -1085,10 +1095,10 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 
 	if (!zerocopy) {
 		copylen = len;
-		if (gso.hdr_len > good_linear)
+		if (tun16_to_cpu(tun, gso.hdr_len) > good_linear)
 			linear = good_linear;
 		else
-			linear = gso.hdr_len;
+			linear = tun16_to_cpu(tun, gso.hdr_len);
 	}
 
 	skb = tun_alloc_skb(tfile, align, copylen, linear, noblock);
@@ -1115,8 +1125,8 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 	}
 
 	if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
-		if (!skb_partial_csum_set(skb, gso.csum_start,
-					  gso.csum_offset)) {
+		if (!skb_partial_csum_set(skb, tun16_to_cpu(tun, gso.csum_start),
+					  tun16_to_cpu(tun, gso.csum_offset))) {
 			tun->dev->stats.rx_frame_errors++;
 			kfree_skb(skb);
 			return -EINVAL;
@@ -1184,7 +1194,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 		if (gso.gso_type & VIRTIO_NET_HDR_GSO_ECN)
 			skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
 
-		skb_shinfo(skb)->gso_size = gso.gso_size;
+		skb_shinfo(skb)->gso_size = tun16_to_cpu(tun, gso.gso_size);
 		if (skb_shinfo(skb)->gso_size == 0) {
 			tun->dev->stats.rx_frame_errors++;
 			kfree_skb(skb);
@@ -1276,8 +1286,8 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 			struct skb_shared_info *sinfo = skb_shinfo(skb);
 
 			/* This is a hint as to how much should be linear. */
-			gso.hdr_len = skb_headlen(skb);
-			gso.gso_size = sinfo->gso_size;
+			gso.hdr_len = cpu_to_tun16(tun, skb_headlen(skb));
+			gso.gso_size = cpu_to_tun16(tun, sinfo->gso_size);
 			if (sinfo->gso_type & SKB_GSO_TCPV4)
 				gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
 			else if (sinfo->gso_type & SKB_GSO_TCPV6)
@@ -1285,12 +1295,12 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 			else {
 				pr_err("unexpected GSO type: "
 				       "0x%x, gso_size %d, hdr_len %d\n",
-				       sinfo->gso_type, gso.gso_size,
-				       gso.hdr_len);
+				       sinfo->gso_type, tun16_to_cpu(tun, gso.gso_size),
+				       tun16_to_cpu(tun, gso.hdr_len));
 				print_hex_dump(KERN_ERR, "tun: ",
 					       DUMP_PREFIX_NONE,
 					       16, 1, skb->head,
-					       min((int)gso.hdr_len, 64), true);
+					       min((int)tun16_to_cpu(tun, gso.hdr_len), 64), true);
 				WARN_ON_ONCE(1);
 				return -EINVAL;
 			}
@@ -1301,9 +1311,9 @@ static ssize_t tun_put_user(struct tun_struct *tun,
 
 		if (skb->ip_summed == CHECKSUM_PARTIAL) {
 			gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-			gso.csum_start = skb_checksum_start_offset(skb) +
-					 vlan_hlen;
-			gso.csum_offset = skb->csum_offset;
+			gso.csum_start = cpu_to_tun16(tun, skb_checksum_start_offset(skb) +
+						      vlan_hlen);
+			gso.csum_offset = cpu_to_tun16(tun, skb->csum_offset);
 		} else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
 			gso.flags = VIRTIO_NET_HDR_F_DATA_VALID;
 		} /* else everything is zero */