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Commit 2eb783c4 authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

tun: Fix TUN_PKT_STRIP setting 



We set the flag TUN_PKT_STRIP if the user buffer provided is too
small to contain the entire packet plus meta-data.  However, this
has been broken ever since we added GSO meta-data.  VLAN acceleration
also has the same problem.

This patch fixes this by taking both into account when setting the
TUN_PKT_STRIP flag.

The fact that this has been broken for six years without anyone
realising means that nobody actually uses this flag.

Fixes: f43798c2 ("tun: Allow GSO using virtio_net_hdr")
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a8f9bfdf

drivers/net/tun.c

+8 −4
Original line number Diff line number Diff line
@@ -1236,15 +1236,19 @@ static ssize_t tun_put_user(struct tun_struct *tun, 
	ssize_t total = 0;

	int vlan_offset = 0, copied;

	int vlan_hlen = 0;

	int vnet_hdr_sz = 0;



	if (vlan_tx_tag_present(skb))

		vlan_hlen = VLAN_HLEN;



	if (tun->flags & TUN_VNET_HDR)

		vnet_hdr_sz = tun->vnet_hdr_sz;



	if (!(tun->flags & TUN_NO_PI)) {

		if ((len -= sizeof(pi)) < 0)

			return -EINVAL;



		if (len < skb->len) {

		if (len < skb->len + vlan_hlen + vnet_hdr_sz) {

			/* Packet will be striped */

			pi.flags |= TUN_PKT_STRIP;

		}
@@ -1254,9 +1258,9 @@ static ssize_t tun_put_user(struct tun_struct *tun, 
		total += sizeof(pi);

	}



	if (tun->flags & TUN_VNET_HDR) {

	if (vnet_hdr_sz) {

		struct virtio_net_hdr gso = { 0 }; /* no info leak */

		if ((len -= tun->vnet_hdr_sz) < 0)

		if ((len -= vnet_hdr_sz) < 0)

			return -EINVAL;



		if (skb_is_gso(skb)) {
@@ -1298,7 +1302,7 @@ static ssize_t tun_put_user(struct tun_struct *tun, 
		if (unlikely(memcpy_toiovecend(iv, (void *)&gso, total,

					       sizeof(gso))))

			return -EFAULT;

		total += tun->vnet_hdr_sz;

		total += vnet_hdr_sz;

	}



	copied = total;