[PATCH net 2/2] macvtap: signal truncated packets

Jason Wang
2013-12-09T10:25:52Z

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>
---
The patch is needed for stable.
---
drivers/net/macvtap.c | 27 ++++++++++++++-------------
1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index 957cc5c..7544a0c 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:
--
1.8.3.2