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>

1 files changed, 14 insertions, 13 deletions

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 957cc5c3653d..7544a0c686b4 100644
--- 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: