Fix AF_PACKET ABI breakage in 4.2

Commit 7d82410950aa ("virtio: add explicit big-endian support to memory
accessors") accidentally changed the virtio_net header used by
AF_PACKET with PACKET_VNET_HDR from host-endian to big-endian.

Since virtio_legacy_is_little_endian() is a very long identifier,
define a vio_le macro and use that throughout the code instead of the
hard-coded 'false' for little-endian.

This restores the ABI to match 4.1 and earlier kernels, and makes my
test program work again.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 15 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 7b8e39a22387..aa4b15c35884 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -230,6 +230,8 @@ struct packet_skb_cb {
         } sa;
 };
 
+#define vio_le() virtio_legacy_is_little_endian()
+
 #define PACKET_SKB_CB(__skb)    ((struct packet_skb_cb *)((__skb)->cb))
 
 #define GET_PBDQC_FROM_RB(x)    ((struct tpacket_kbdq_core *)(&(x)->prb_bdqc))
@@ -2680,15 +2682,15 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
                         goto out_unlock;
 
                 if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
-                    (__virtio16_to_cpu(false, vnet_hdr.csum_start) +
-                     __virtio16_to_cpu(false, vnet_hdr.csum_offset) + 2 >
-                      __virtio16_to_cpu(false, vnet_hdr.hdr_len)))
-                        vnet_hdr.hdr_len = __cpu_to_virtio16(false,
-                                 __virtio16_to_cpu(false, vnet_hdr.csum_start) +
-                                __virtio16_to_cpu(false, vnet_hdr.csum_offset) + 2);
+                    (__virtio16_to_cpu(vio_le(), vnet_hdr.csum_start) +
+                     __virtio16_to_cpu(vio_le(), vnet_hdr.csum_offset) + 2 >
+                      __virtio16_to_cpu(vio_le(), vnet_hdr.hdr_len)))
+                        vnet_hdr.hdr_len = __cpu_to_virtio16(vio_le(),
+                                 __virtio16_to_cpu(vio_le(), vnet_hdr.csum_start) +
+                                __virtio16_to_cpu(vio_le(), vnet_hdr.csum_offset) + 2);
 
                 err = -EINVAL;
-                if (__virtio16_to_cpu(false, vnet_hdr.hdr_len) > len)
+                if (__virtio16_to_cpu(vio_le(), vnet_hdr.hdr_len) > len)
                         goto out_unlock;
 
                 if (vnet_hdr.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
@@ -2731,7 +2733,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
         hlen = LL_RESERVED_SPACE(dev);
         tlen = dev->needed_tailroom;
         skb = packet_alloc_skb(sk, hlen + tlen, hlen, len,
-                               __virtio16_to_cpu(false, vnet_hdr.hdr_len),
+                               __virtio16_to_cpu(vio_le(), vnet_hdr.hdr_len),
                                msg->msg_flags & MSG_DONTWAIT, &err);
         if (skb == NULL)
                 goto out_unlock;
@@ -2778,8 +2780,8 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
 
         if (po->has_vnet_hdr) {
                 if (vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
-                        u16 s = __virtio16_to_cpu(false, vnet_hdr.csum_start);
-                        u16 o = __virtio16_to_cpu(false, vnet_hdr.csum_offset);
+                        u16 s = __virtio16_to_cpu(vio_le(), vnet_hdr.csum_start);
+                        u16 o = __virtio16_to_cpu(vio_le(), vnet_hdr.csum_offset);
                         if (!skb_partial_csum_set(skb, s, o)) {
                                 err = -EINVAL;
                                 goto out_free;
@@ -2787,7 +2789,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
                 }
 
                 skb_shinfo(skb)->gso_size =
-                        __virtio16_to_cpu(false, vnet_hdr.gso_size);
+                        __virtio16_to_cpu(vio_le(), vnet_hdr.gso_size);
                 skb_shinfo(skb)->gso_type = gso_type;
 
                 /* Header must be checked, and gso_segs computed. */
@@ -3161,9 +3163,9 @@ static int packet_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 
                         /* This is a hint as to how much should be linear. */
                         vnet_hdr.hdr_len =
-                                __cpu_to_virtio16(false, skb_headlen(skb));
+                                __cpu_to_virtio16(vio_le(), skb_headlen(skb));
                         vnet_hdr.gso_size =
-                                __cpu_to_virtio16(false, sinfo->gso_size);
+                                __cpu_to_virtio16(vio_le(), sinfo->gso_size);
                         if (sinfo->gso_type & SKB_GSO_TCPV4)
                                 vnet_hdr.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
                         else if (sinfo->gso_type & SKB_GSO_TCPV6)
@@ -3181,9 +3183,9 @@ static int packet_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
 
                 if (skb->ip_summed == CHECKSUM_PARTIAL) {
                         vnet_hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-                        vnet_hdr.csum_start = __cpu_to_virtio16(false,
+                        vnet_hdr.csum_start = __cpu_to_virtio16(vio_le(),
                                           skb_checksum_start_offset(skb));
-                        vnet_hdr.csum_offset = __cpu_to_virtio16(false,
+                        vnet_hdr.csum_offset = __cpu_to_virtio16(vio_le(),
                                                          skb->csum_offset);
                 } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
                         vnet_hdr.flags = VIRTIO_NET_HDR_F_DATA_VALID;