net: in virtio_net_hdr only add VLAN_HLEN to csum_start if payload holds vlan

[ Upstream commit fd3a88625844907151737fc3b4201676effa6d27 ]

Tun, tap, virtio, packet and uml vector all use struct virtio_net_hdr
to communicate packet metadata to userspace.

For skbuffs with vlan, the first two return the packet as it may have
existed on the wire, inserting the VLAN tag in the user buffer.  Then
virtio_net_hdr.csum_start needs to be adjusted by VLAN_HLEN bytes.

Commit f09e2249c4f5 ("macvtap: restore vlan header on user read")
added this feature to macvtap. Commit 3ce9b20f1971 ("macvtap: Fix
csum_start when VLAN tags are present") then fixed up csum_start.

Virtio, packet and uml do not insert the vlan header in the user
buffer.

When introducing virtio_net_hdr_from_skb to deduplicate filling in
the virtio_net_hdr, the variant from macvtap which adds VLAN_HLEN was
applied uniformly, breaking csum offset for packets with vlan on
virtio and packet.

Make insertion of VLAN_HLEN optional. Convert the callers to pass it
when needed.

Fixes: e858fae2b0b8f4 ("virtio_net: use common code for virtio_net_hdr and skb GSO conversion")
Fixes: 1276f24eeef2 ("packet: use common code for virtio_net_hdr and skb GSO conversion")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index bfd4ded0a53fb015226d0b03ceb9e5dda9f904e5..773a3fea8f0eb50d29e231b5fa95b49e15549f96 100644 (file)
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -777,13 +777,16 @@ static ssize_t tap_put_user(struct tap_queue *q,
        int total;
 
        if (q->flags & IFF_VNET_HDR) {
+               int vlan_hlen = skb_vlan_tag_present(skb) ? VLAN_HLEN : 0;
                struct virtio_net_hdr vnet_hdr;
+
                vnet_hdr_len = READ_ONCE(q->vnet_hdr_sz);
                if (iov_iter_count(iter) < vnet_hdr_len)
                        return -EINVAL;
 
                if (virtio_net_hdr_from_skb(skb, &vnet_hdr,
-                                           tap_is_little_endian(q), true))
+                                           tap_is_little_endian(q), true,
+                                           vlan_hlen))
                        BUG();
 
                if (copy_to_iter(&vnet_hdr, sizeof(vnet_hdr), iter) !=

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 3d9ad11e4f28196e2603524535da2b8a10ffd8d4..cb17ffadfc30ef6f9230bfc4149265b921912c0f 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1648,7 +1648,8 @@ static ssize_t tun_put_user(struct tun_struct *tun,
                        return -EINVAL;
 
                if (virtio_net_hdr_from_skb(skb, &gso,
-                                           tun_is_little_endian(tun), true)) {
+                                           tun_is_little_endian(tun), true,
+                                           vlan_hlen)) {
                        struct skb_shared_info *sinfo = skb_shinfo(skb);
                        pr_err("unexpected GSO type: "
                               "0x%x, gso_size %d, hdr_len %d\n",

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 9e93e7a5df7eee0c6442dcc8f7e1e6b7a0fb0d7d..910c46b4776999e9f43251801c0cc65a70d186b2 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1237,7 +1237,8 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb)
                hdr = skb_vnet_hdr(skb);
 
        if (virtio_net_hdr_from_skb(skb, &hdr->hdr,
-                                   virtio_is_little_endian(vi->vdev), false))
+                                   virtio_is_little_endian(vi->vdev), false,
+                                   0))
                BUG();
 
        if (vi->mergeable_rx_bufs)

diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index f144216febc642fd70512df9dddefe1a7f119478..9397628a196714dc2177552465fe91fd18b9627d 100644 (file)
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -58,7 +58,8 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
 static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
                                          struct virtio_net_hdr *hdr,
                                          bool little_endian,
-                                         bool has_data_valid)
+                                         bool has_data_valid,
+                                         int vlan_hlen)
 {
        memset(hdr, 0, sizeof(*hdr));   /* no info leak */
 
@@ -83,12 +84,8 @@ static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
 
        if (skb->ip_summed == CHECKSUM_PARTIAL) {
                hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-               if (skb_vlan_tag_present(skb))
-                       hdr->csum_start = __cpu_to_virtio16(little_endian,
-                               skb_checksum_start_offset(skb) + VLAN_HLEN);
-               else
-                       hdr->csum_start = __cpu_to_virtio16(little_endian,
-                               skb_checksum_start_offset(skb));
+               hdr->csum_start = __cpu_to_virtio16(little_endian,
+                       skb_checksum_start_offset(skb) + vlan_hlen);
                hdr->csum_offset = __cpu_to_virtio16(little_endian,
                                skb->csum_offset);
        } else if (has_data_valid &&

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 7806e166669a836e18145fb69587a595e1dcd60b..4fe2e34522d6c1512d3235aa7ab8199fc5f8138f 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2046,7 +2046,7 @@ static int packet_rcv_vnet(struct msghdr *msg, const struct sk_buff *skb,
                return -EINVAL;
        *len -= sizeof(vnet_hdr);
 
-       if (virtio_net_hdr_from_skb(skb, &vnet_hdr, vio_le(), true))
+       if (virtio_net_hdr_from_skb(skb, &vnet_hdr, vio_le(), true, 0))
                return -EINVAL;
 
        return memcpy_to_msg(msg, (void *)&vnet_hdr, sizeof(vnet_hdr));
@@ -2313,7 +2313,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
        if (do_vnet) {
                if (virtio_net_hdr_from_skb(skb, h.raw + macoff -
                                            sizeof(struct virtio_net_hdr),
-                                           vio_le(), true)) {
+                                           vio_le(), true, 0)) {
                        spin_lock(&sk->sk_receive_queue.lock);
                        goto drop_n_account;
                }