tunnels: Don't apply GRO to multiple layers of encapsulation.

When drivers express support for TSO of encapsulated packets, they
only mean that they can do it for one layer of encapsulation.
Supporting additional levels would mean updating, at a minimum,
more IP length fields and they are unaware of this.

No encapsulation device expresses support for handling offloaded
encapsulated packets, so we won't generate these types of frames
in the transmit path. However, GRO doesn't have a check for
multiple levels of encapsulation and will attempt to build them.

UDP tunnel GRO actually does prevent this situation but it only
handles multiple UDP tunnels stacked on top of each other. This
generalizes that solution to prevent any kind of tunnel stacking
that would cause problems.

Fixes: bf5a755f ("net-gre-gro: Add GRE support to the GRO stack")
Signed-off-by: Jesse Gross <jesse@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
		unsigned char name_assign_type,
		void (*setup)(struct net_device *),
		unsigned int txqs, unsigned int rxqs)
{
	struct net_device *dev;
	size_t alloc_size;
	struct net_device *p;

	BUG_ON(strlen(name) >= sizeof(dev->name));

	if (txqs < 1) {
		pr_err("alloc_netdev: Unable to allocate device with zero queues\n");
		return NULL;
	}

#ifdef CONFIG_SYSFS
	if (rxqs < 1) {
		pr_err("alloc_netdev: Unable to allocate device with zero RX queues\n");
		return NULL;
	}
#endif

	alloc_size = sizeof(struct net_device);
	if (sizeof_priv) {
		/* ensure 32-byte alignment of private area */
		alloc_size = ALIGN(alloc_size, NETDEV_ALIGN);
		alloc_size += sizeof_priv;
	}
	/* ensure 32-byte alignment of whole construct */
	alloc_size += NETDEV_ALIGN - 1;

	p = kzalloc(alloc_size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
	if (!p)
		p = vzalloc(alloc_size);
	if (!p)
		return NULL;

	dev = PTR_ALIGN(p, NETDEV_ALIGN);
	dev->padded = (char *)dev - (char *)p;

	dev->pcpu_refcnt = alloc_percpu(int);
	if (!dev->pcpu_refcnt)
		goto free_dev;

	if (dev_addr_init(dev))
		goto free_pcpu;

	dev_mc_init(dev);
	dev_uc_init(dev);

	dev_net_set(dev, &init_net);

	dev->gso_max_size = GSO_MAX_SIZE;
	dev->gso_max_segs = GSO_MAX_SEGS;
	dev->gso_min_segs = 0;

	INIT_LIST_HEAD(&dev->napi_list);
	INIT_LIST_HEAD(&dev->unreg_list);
	INIT_LIST_HEAD(&dev->close_list);
	INIT_LIST_HEAD(&dev->link_watch_list);
	INIT_LIST_HEAD(&dev->adj_list.upper);
	INIT_LIST_HEAD(&dev->adj_list.lower);
	INIT_LIST_HEAD(&dev->all_adj_list.upper);
	INIT_LIST_HEAD(&dev->all_adj_list.lower);
	INIT_LIST_HEAD(&dev->ptype_all);
	INIT_LIST_HEAD(&dev->ptype_specific);
	dev->priv_flags = IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM;
	setup(dev);

	if (!dev->tx_queue_len) {
		dev->priv_flags |= IFF_NO_QUEUE;
		dev->tx_queue_len = 1;
	}

	dev->num_tx_queues = txqs;
	dev->real_num_tx_queues = txqs;
	if (netif_alloc_netdev_queues(dev))
		goto free_all;

#ifdef CONFIG_SYSFS
	dev->num_rx_queues = rxqs;
	dev->real_num_rx_queues = rxqs;
	if (netif_alloc_rx_queues(dev))
		goto free_all;
#endif

	strcpy(dev->name, name);
	dev->name_assign_type = name_assign_type;
	dev->group = INIT_NETDEV_GROUP;
	if (!dev->ethtool_ops)
		dev->ethtool_ops = &default_ethtool_ops;

	nf_hook_ingress_init(dev);

	return dev;

free_all:
	free_netdev(dev);
	return NULL;

free_pcpu:
	free_percpu(dev->pcpu_refcnt);
free_dev:
	netdev_freemem(dev);
	return NULL;
}

struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
		unsigned char name_assign_type,
		void (*setup)(struct net_device *),
		unsigned int txqs, unsigned int rxqs)
{
	struct net_device *dev;
	size_t alloc_size;
	struct net_device *p;

	BUG_ON(strlen(name) >= sizeof(dev->name));

	if (txqs < 1) {
		pr_err("alloc_netdev: Unable to allocate device with zero queues\n");
		return NULL;
	}

#ifdef CONFIG_SYSFS
	if (rxqs < 1) {
		pr_err("alloc_netdev: Unable to allocate device with zero RX queues\n");
		return NULL;
	}
#endif

	alloc_size = sizeof(struct net_device);
	if (sizeof_priv) {
		/* ensure 32-byte alignment of private area */
		alloc_size = ALIGN(alloc_size, NETDEV_ALIGN);
		alloc_size += sizeof_priv;
	}
	/* ensure 32-byte alignment of whole construct */
	alloc_size += NETDEV_ALIGN - 1;

	p = kzalloc(alloc_size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
	if (!p)
		p = vzalloc(alloc_size);
	if (!p)
		return NULL;

	dev = PTR_ALIGN(p, NETDEV_ALIGN);
	dev->padded = (char *)dev - (char *)p;

	dev->pcpu_refcnt = alloc_percpu(int);
	if (!dev->pcpu_refcnt)
		goto free_dev;

	if (dev_addr_init(dev))
		goto free_pcpu;

	dev_mc_init(dev);
	dev_uc_init(dev);

	dev_net_set(dev, &init_net);

	dev->gso_max_size = GSO_MAX_SIZE;
	dev->gso_max_segs = GSO_MAX_SEGS;
	dev->gso_min_segs = 0;

	INIT_LIST_HEAD(&dev->napi_list);
	INIT_LIST_HEAD(&dev->unreg_list);
	INIT_LIST_HEAD(&dev->close_list);
	INIT_LIST_HEAD(&dev->link_watch_list);
	INIT_LIST_HEAD(&dev->adj_list.upper);
	INIT_LIST_HEAD(&dev->adj_list.lower);
	INIT_LIST_HEAD(&dev->all_adj_list.upper);
	INIT_LIST_HEAD(&dev->all_adj_list.lower);
	INIT_LIST_HEAD(&dev->ptype_all);
	INIT_LIST_HEAD(&dev->ptype_specific);
	dev->priv_flags = IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM;
	setup(dev);

	if (!dev->tx_queue_len) {
		dev->priv_flags |= IFF_NO_QUEUE;
		dev->tx_queue_len = 1;
	}

	dev->num_tx_queues = txqs;
	dev->real_num_tx_queues = txqs;
	if (netif_alloc_netdev_queues(dev))
		goto free_all;

#ifdef CONFIG_SYSFS
	dev->num_rx_queues = rxqs;
	dev->real_num_rx_queues = rxqs;
	if (netif_alloc_rx_queues(dev))
		goto free_all;
#endif

	strcpy(dev->name, name);
	dev->name_assign_type = name_assign_type;
	dev->group = INIT_NETDEV_GROUP;
	if (!dev->ethtool_ops)
		dev->ethtool_ops = &default_ethtool_ops;

	nf_hook_ingress_init(dev);

	return dev;

free_all:
	free_netdev(dev);
	return NULL;

free_pcpu:
	free_percpu(dev->pcpu_refcnt);
free_dev:
	netdev_freemem(dev);
	return NULL;
}
