macvtap: add ioctl to modify vnet header size

This adds TUNSETVNETHDRSZ/TUNGETVNETHDRSZ support
to macvtap.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 1c4110d..a8a94e2 100644 (file)
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -38,6 +38,7 @@ struct macvtap_queue {
        struct sock sk;
        struct socket sock;
        struct socket_wq wq;
+       int vnet_hdr_sz;
        struct macvlan_dev *vlan;
        struct file *file;
        unsigned int flags;
@@ -285,6 +286,7 @@ static int macvtap_open(struct inode *inode, struct file *file)
        sock_init_data(&q->sock, &q->sk);
        q->sk.sk_write_space = macvtap_sock_write_space;
        q->flags = IFF_VNET_HDR | IFF_NO_PI | IFF_TAP;
+       q->vnet_hdr_sz = sizeof(struct virtio_net_hdr);
 
        err = macvtap_set_queue(dev, file, q);
        if (err)
@@ -445,14 +447,14 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q,
        int vnet_hdr_len = 0;
 
        if (q->flags & IFF_VNET_HDR) {
-               vnet_hdr_len = sizeof(vnet_hdr);
+               vnet_hdr_len = q->vnet_hdr_sz;
 
                err = -EINVAL;
                if ((len -= vnet_hdr_len) < 0)
                        goto err;
 
                err = memcpy_fromiovecend((void *)&vnet_hdr, iv, 0,
-                                          vnet_hdr_len);
+                                          sizeof(vnet_hdr));
                if (err < 0)
                        goto err;
                if ((vnet_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
@@ -534,7 +536,7 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
 
        if (q->flags & IFF_VNET_HDR) {
                struct virtio_net_hdr vnet_hdr;
-               vnet_hdr_len = sizeof (vnet_hdr);
+               vnet_hdr_len = q->vnet_hdr_sz;
                if ((len -= vnet_hdr_len) < 0)
                        return -EINVAL;
 
@@ -542,7 +544,7 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
                if (ret)
                        return ret;
 
-               if (memcpy_toiovecend(iv, (void *)&vnet_hdr, 0, vnet_hdr_len))
+               if (memcpy_toiovecend(iv, (void *)&vnet_hdr, 0, sizeof(vnet_hdr)))
                        return -EFAULT;
        }
 
@@ -627,6 +629,8 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
        struct ifreq __user *ifr = argp;
        unsigned int __user *up = argp;
        unsigned int u;
+       int __user *sp = argp;
+       int s;
        int ret;
 
        switch (cmd) {
@@ -672,6 +676,21 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
                q->sk.sk_sndbuf = u;
                return 0;
 
+       case TUNGETVNETHDRSZ:
+               s = q->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;
+
+               q->vnet_hdr_sz = s;
+               return 0;
+
        case TUNSETOFFLOAD:
                /* let the user check for future flags */
                if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |