[PATCH 3.8 144/166] macvtap: signal truncated packets

Kamal Mostafa
2014-01-15T21:52:38Z

From: Jason Wang <jasowang@redhat.com>

[ Upstream commit ce232ce01d61b184202bb185103d119820e1260c ]

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 trunca
checking work.

Cc: Vlad Yasevich <vyasevich@gmail.com>
Cc: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
drivers/net/macvtap.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index c8c9bcc..894613c 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -808,7 +808,7 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
int ret;
int vnet_hdr_len = 0;
int vlan_offset = 0;
- int copied;
+ int copied, total;

if (q->flags & IFF_VNET_HDR) {
struct virtio_net_hdr vnet_hdr;
@@ -823,7 +823,8 @@ 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;
+ total = copied = vnet_hdr_len;
+ total += skb->len;

if (!vlan_tx_tag_present(skb))
len = min_t(int, skb->len, len);
@@ -838,6 +839,7 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,

vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
len = min_t(int, skb->len + VLAN_HLEN, len);
+ total += VLAN_HLEN;

copy = min_t(int, vlan_offset, len);
ret = skb_copy_datagram_const_iovec(skb, 0, iv, copied, copy);
@@ -855,10 +857,9 @@ static ssize_t macvtap_put_user(struct macvtap_queue *q,
}

ret = skb_copy_datagram_const_iovec(skb, vlan_offset, iv, copied, len);
- copied += len;

done:
- return ret ? ret : copied;
+ return ret ? ret : total;
}

static ssize_t macvtap_do_read(struct macvtap_queue *q, struct kiocb *iocb,
@@ -910,7 +911,7 @@ 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:
--
1.8.3.2