net: Audit drivers to identify those needing IFF_TX_SKB_SHARING cleared

After the last patch, We are left in a state in which only drivers calling
ether_setup have IFF_TX_SKB_SHARING set (we assume that drivers touching real
hardware call ether_setup for their net_devices and don't hold any state in
their skbs.  There are a handful of drivers that violate this assumption of
course, and need to be fixed up.  This patch identifies those drivers, and marks
them as not being able to support the safe transmission of skbs by clearning the
IFF_TX_SKB_SHARING flag in priv_flags

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Karsten Keil <isdn@linux-pingi.de>
CC: "David S. Miller" <davem@davemloft.net>
CC: Jay Vosburgh <fubar@us.ibm.com>
CC: Andy Gospodarek <andy@greyhouse.net>
CC: Patrick McHardy <kaber@trash.net>
CC: Krzysztof Halasa <khc@pm.waw.pl>
CC: "John W. Linville" <linville@tuxdriver.com>
CC: Greg Kroah-Hartman <gregkh@suse.de>
CC: Marcel Holtmann <marcel@holtmann.org>
CC: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
static ssize_t tun_get_user(struct tun_struct *tun,
			    const struct iovec *iv, size_t count,
			    int noblock)
{
	struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) };
	struct sk_buff *skb;
	size_t len = count, align = NET_SKB_PAD;
	struct virtio_net_hdr gso = { 0 };
	int offset = 0;

	if (!(tun->flags & TUN_NO_PI)) {
		if ((len -= sizeof(pi)) > count)
			return -EINVAL;

		if (memcpy_fromiovecend((void *)&pi, iv, 0, sizeof(pi)))
			return -EFAULT;
		offset += sizeof(pi);
	}

	if (tun->flags & TUN_VNET_HDR) {
		if ((len -= tun->vnet_hdr_sz) > count)
			return -EINVAL;

		if (memcpy_fromiovecend((void *)&gso, iv, offset, sizeof(gso)))
			return -EFAULT;

		if ((gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
		    gso.csum_start + gso.csum_offset + 2 > gso.hdr_len)
			gso.hdr_len = gso.csum_start + gso.csum_offset + 2;

		if (gso.hdr_len > len)
			return -EINVAL;
		offset += tun->vnet_hdr_sz;
	}

	if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV) {
		align += NET_IP_ALIGN;
		if (unlikely(len < ETH_HLEN ||
			     (gso.hdr_len && gso.hdr_len < ETH_HLEN)))
			return -EINVAL;
	}

	skb = tun_alloc_skb(tun, align, len, gso.hdr_len, noblock);
	if (IS_ERR(skb)) {
		if (PTR_ERR(skb) != -EAGAIN)
			tun->dev->stats.rx_dropped++;
		return PTR_ERR(skb);
	}

	if (skb_copy_datagram_from_iovec(skb, 0, iv, offset, len)) {
		tun->dev->stats.rx_dropped++;
		kfree_skb(skb);
		return -EFAULT;
	}

	if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
		if (!skb_partial_csum_set(skb, gso.csum_start,
					  gso.csum_offset)) {
			tun->dev->stats.rx_frame_errors++;
			kfree_skb(skb);
			return -EINVAL;
		}
	}

	switch (tun->flags & TUN_TYPE_MASK) {
	case TUN_TUN_DEV:
		if (tun->flags & TUN_NO_PI) {
			switch (skb->data[0] & 0xf0) {
			case 0x40:
				pi.proto = htons(ETH_P_IP);
				break;
			case 0x60:
				pi.proto = htons(ETH_P_IPV6);
				break;
			default:
				tun->dev->stats.rx_dropped++;
				kfree_skb(skb);
				return -EINVAL;
			}
		}

		skb_reset_mac_header(skb);
		skb->protocol = pi.proto;
		skb->dev = tun->dev;
		break;
	case TUN_TAP_DEV:
		skb->protocol = eth_type_trans(skb, tun->dev);
		break;
	}

	if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
		pr_debug("GSO!\n");
		switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
		case VIRTIO_NET_HDR_GSO_TCPV4:
			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
			break;
		case VIRTIO_NET_HDR_GSO_TCPV6:
			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
			break;
		case VIRTIO_NET_HDR_GSO_UDP:
			skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
			break;
		default:
			tun->dev->stats.rx_frame_errors++;
			kfree_skb(skb);
			return -EINVAL;
		}

		if (gso.gso_type & VIRTIO_NET_HDR_GSO_ECN)
			skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;

		skb_shinfo(skb)->gso_size = gso.gso_size;
		if (skb_shinfo(skb)->gso_size == 0) {
			tun->dev->stats.rx_frame_errors++;
			kfree_skb(skb);
			return -EINVAL;
		}

		/* Header must be checked, and gso_segs computed. */
		skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
		skb_shinfo(skb)->gso_segs = 0;
	}

	netif_rx_ni(skb);

	tun->dev->stats.rx_packets++;
	tun->dev->stats.rx_bytes += len;

	return count;
}

static ssize_t tun_get_user(struct tun_struct *tun,
			    const struct iovec *iv, size_t count,
			    int noblock)
{
	struct tun_pi pi = { 0, cpu_to_be16(ETH_P_IP) };
	struct sk_buff *skb;
	size_t len = count, align = NET_SKB_PAD;
	struct virtio_net_hdr gso = { 0 };
	int offset = 0;

	if (!(tun->flags & TUN_NO_PI)) {
		if ((len -= sizeof(pi)) > count)
			return -EINVAL;

		if (memcpy_fromiovecend((void *)&pi, iv, 0, sizeof(pi)))
			return -EFAULT;
		offset += sizeof(pi);
	}

	if (tun->flags & TUN_VNET_HDR) {
		if ((len -= tun->vnet_hdr_sz) > count)
			return -EINVAL;

		if (memcpy_fromiovecend((void *)&gso, iv, offset, sizeof(gso)))
			return -EFAULT;

		if ((gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
		    gso.csum_start + gso.csum_offset + 2 > gso.hdr_len)
			gso.hdr_len = gso.csum_start + gso.csum_offset + 2;

		if (gso.hdr_len > len)
			return -EINVAL;
		offset += tun->vnet_hdr_sz;
	}

	if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV) {
		align += NET_IP_ALIGN;
		if (unlikely(len < ETH_HLEN ||
			     (gso.hdr_len && gso.hdr_len < ETH_HLEN)))
			return -EINVAL;
	}

	skb = tun_alloc_skb(tun, align, len, gso.hdr_len, noblock);
	if (IS_ERR(skb)) {
		if (PTR_ERR(skb) != -EAGAIN)
			tun->dev->stats.rx_dropped++;
		return PTR_ERR(skb);
	}

	if (skb_copy_datagram_from_iovec(skb, 0, iv, offset, len)) {
		tun->dev->stats.rx_dropped++;
		kfree_skb(skb);
		return -EFAULT;
	}

	if (gso.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
		if (!skb_partial_csum_set(skb, gso.csum_start,
					  gso.csum_offset)) {
			tun->dev->stats.rx_frame_errors++;
			kfree_skb(skb);
			return -EINVAL;
		}
	}

	switch (tun->flags & TUN_TYPE_MASK) {
	case TUN_TUN_DEV:
		if (tun->flags & TUN_NO_PI) {
			switch (skb->data[0] & 0xf0) {
			case 0x40:
				pi.proto = htons(ETH_P_IP);
				break;
			case 0x60:
				pi.proto = htons(ETH_P_IPV6);
				break;
			default:
				tun->dev->stats.rx_dropped++;
				kfree_skb(skb);
				return -EINVAL;
			}
		}

		skb_reset_mac_header(skb);
		skb->protocol = pi.proto;
		skb->dev = tun->dev;
		break;
	case TUN_TAP_DEV:
		skb->protocol = eth_type_trans(skb, tun->dev);
		break;
	}

	if (gso.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
		pr_debug("GSO!\n");
		switch (gso.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
		case VIRTIO_NET_HDR_GSO_TCPV4:
			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
			break;
		case VIRTIO_NET_HDR_GSO_TCPV6:
			skb_shinfo(skb)->gso_type = SKB_GSO_TCPV6;
			break;
		case VIRTIO_NET_HDR_GSO_UDP:
			skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
			break;
		default:
			tun->dev->stats.rx_frame_errors++;
			kfree_skb(skb);
			return -EINVAL;
		}

		if (gso.gso_type & VIRTIO_NET_HDR_GSO_ECN)
			skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;

		skb_shinfo(skb)->gso_size = gso.gso_size;
		if (skb_shinfo(skb)->gso_size == 0) {
			tun->dev->stats.rx_frame_errors++;
			kfree_skb(skb);
			return -EINVAL;
		}

		/* Header must be checked, and gso_segs computed. */
		skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
		skb_shinfo(skb)->gso_segs = 0;
	}

	netif_rx_ni(skb);

	tun->dev->stats.rx_packets++;
	tun->dev->stats.rx_bytes += len;

	return count;
}
