macvtap: signal truncated packets

macvtap_put_user() never return a value grater than iov length, this in fact
bypasses the truncated checking in macvtap_recvmsg(). Fix this by always
returning the size of packet plus the possible vlan header to let the truncated
checking work.

Cc: Vlad Yasevich <vyasevich@gmail.com>
Cc: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 957cc5c..7544a0c 100644 (file)
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -767,10 +767,14 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
                                const struct sk_buff *skb,
                                const struct iovec *iv, int len)
 {
-       int ret;
+       int ret, off;
        int vnet_hdr_len = 0;
        int vlan_offset = 0;
        int copied;
+       struct {
+               __be16 h_vlan_proto;
+               __be16 h_vlan_TCI;
+       } veth;
 
        if (q->flags & IFF_VNET_HDR) {
                struct virtio_net_hdr vnet_hdr;
@@ -785,16 +789,13 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
                if (memcpy_toiovecend(iv, (void *)&vnet_hdr, 0, sizeof(vnet_hdr)))
                        return -EFAULT;
        }
-       copied = vnet_hdr_len;
+       off = copied = vnet_hdr_len;
 
        if (!vlan_tx_tag_present(skb))
                len = min_t(int, skb->len, len);
        else {
                int copy;
-               struct {
-                       __be16 h_vlan_proto;
-                       __be16 h_vlan_TCI;
-               } veth;
+
                veth.h_vlan_proto = skb->vlan_proto;
                veth.h_vlan_TCI = htons(vlan_tx_tag_get(skb));
 
@@ -802,22 +803,22 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
                len = min_t(int, skb->len + VLAN_HLEN, len);
 
                copy = min_t(int, vlan_offset, len);
-               ret = skb_copy_datagram_const_iovec(skb, 0, iv, copied, copy);
+               ret = skb_copy_datagram_const_iovec(skb, 0, iv, off, copy);
                len -= copy;
-               copied += copy;
+               off += copy;
                if (ret || !len)
                        goto done;
 
                copy = min_t(int, sizeof(veth), len);
-               ret = memcpy_toiovecend(iv, (void *)&veth, copied, copy);
+               ret = memcpy_toiovecend(iv, (void *)&veth, off, copy);
                len -= copy;
-               copied += copy;
+               off += copy;
                if (ret || !len)
                        goto done;
        }
 
-       ret = skb_copy_datagram_const_iovec(skb, vlan_offset, iv, copied, len);
-       copied += len;
+       ret = skb_copy_datagram_const_iovec(skb, vlan_offset, iv, off, len);
+       copied += skb->len + (vlan_offset ? sizeof(veth) : 0);
 
 done:
        return ret ? ret : copied;
@@ -875,7 +876,7 @@ static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
        }
 
        ret = macvtap_do_read(q, iocb, iv, len, file->f_flags & O_NONBLOCK);
-       ret = min_t(ssize_t, ret, len); /* XXX copied from tun.c. Why? */
+       ret = min_t(ssize_t, ret, len);
        if (ret > 0)
                iocb->ki_pos = ret;
 out: