tun: Fix TUN_PKT_STRIP setting (2eb783c4) · Commits · 戴 / test

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: ("tun: Allow GSO using virtio_net_hdr") Signed-off-by:

Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by:

David S. Miller <davem@davemloft.net>

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;

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