[net,V2,2/2] 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 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>
---
Changes from v1:
- increase total unconditionally
- do not move the structure veth out of the vlan handling block
---
 drivers/net/macvtap.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

On Tue, Dec 10, 2013 at 01:49:46PM +0800, Jason Wang wrote:
> 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>
> ---
> Changes from v1:
> - increase total unconditionally
> - do not move the structure veth out of the vlan handling block
> ---
>  drivers/net/macvtap.c | 19 ++++++++++---------
>  1 file changed, 10 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
> index 957cc5c..ded4b2c 100644
> --- a/drivers/net/macvtap.c
> +++ b/drivers/net/macvtap.c
> @@ -770,7 +770,7 @@ 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, offset;
>  
>  	if (q->flags & IFF_VNET_HDR) {
>  		struct virtio_net_hdr vnet_hdr;
> @@ -785,7 +785,8 @@ 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;
> +	offset = copied = vnet_hdr_len;
> +	copied += skb->len;
>  
>  	if (!vlan_tx_tag_present(skb))
>  		len = min_t(int, skb->len, len);
> @@ -800,24 +801,24 @@ 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);
> +		copied += VLAN_HLEN;
>  
>  		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, offset, copy);
>  		len -= copy;
> -		copied += copy;
> +		offset += 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, offset, copy);
>  		len -= copy;
> -		copied += copy;
> +		offset += 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, offset, len);
>  
>  done:
>  	return ret ? ret : copied;

I commented on this already. copied is how much we copied,
so its value is correct.
You want to name the new one total_len or something along
these lines and return it.

> @@ -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
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On 12/10/2013 11:29 PM, Michael S. Tsirkin wrote:
> On Tue, Dec 10, 2013 at 01:49:46PM +0800, Jason Wang wrote:
>> > 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>
>> > ---
>> > Changes from v1:
>> > - increase total unconditionally
>> > - do not move the structure veth out of the vlan handling block
>> > ---
>> >  drivers/net/macvtap.c | 19 ++++++++++---------
>> >  1 file changed, 10 insertions(+), 9 deletions(-)
>> > 
>> > diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
>> > index 957cc5c..ded4b2c 100644
>> > --- a/drivers/net/macvtap.c
>> > +++ b/drivers/net/macvtap.c
>> > @@ -770,7 +770,7 @@ 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, offset;
>> >  
>> >  	if (q->flags & IFF_VNET_HDR) {
>> >  		struct virtio_net_hdr vnet_hdr;
>> > @@ -785,7 +785,8 @@ 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;
>> > +	offset = copied = vnet_hdr_len;
>> > +	copied += skb->len;
>> >  
>> >  	if (!vlan_tx_tag_present(skb))
>> >  		len = min_t(int, skb->len, len);
>> > @@ -800,24 +801,24 @@ 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);
>> > +		copied += VLAN_HLEN;
>> >  
>> >  		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, offset, copy);
>> >  		len -= copy;
>> > -		copied += copy;
>> > +		offset += 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, offset, copy);
>> >  		len -= copy;
>> > -		copied += copy;
>> > +		offset += 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, offset, len);
>> >  
>> >  done:
>> >  	return ret ? ret : copied;
> I commented on this already. copied is how much we copied,
> so its value is correct.
> You want to name the new one total_len or something along
> these lines and return it.
>

Ok, to be same with tun, I will use "total" in V3.

Thanks
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