Commit f43798c2 authored by Rusty Russell's avatar Rusty Russell Committed by David S. Miller
Browse files

tun: Allow GSO using virtio_net_hdr 



Add a IFF_VNET_HDR flag.  This uses the same ABI as virtio_net
(ie. prepending struct virtio_net_hdr to packets) to indicate GSO and
checksum information.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Acked-by: default avatarMax Krasnyansky <maxk@qualcomm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5228ddc9

drivers/net/tun.c

+92 −3
Original line number Diff line number Diff line
@@ -63,6 +63,7 @@ 
#include <linux/if_tun.h>

#include <linux/crc32.h>

#include <linux/nsproxy.h>

#include <linux/virtio_net.h>

#include <net/net_namespace.h>

#include <net/netns/generic.h>
@@ -283,6 +284,7 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv, 
	struct tun_pi pi = { 0, __constant_htons(ETH_P_IP) };

	struct sk_buff *skb;

	size_t len = count, align = 0;

	struct virtio_net_hdr gso = { 0 };



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

		if ((len -= sizeof(pi)) > count)
@@ -292,6 +294,17 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv, 
			return -EFAULT;

	}



	if (tun->flags & TUN_VNET_HDR) {

		if ((len -= sizeof(gso)) > count)

			return -EINVAL;



		if (memcpy_fromiovec((void *)&gso, iv, sizeof(gso)))

			return -EFAULT;



		if (gso.hdr_len > len)

			return -EINVAL;

	}



	if ((tun->flags & TUN_TYPE_MASK) == TUN_TAP_DEV) {

		align = NET_IP_ALIGN;

		if (unlikely(len < ETH_HLEN))
@@ -311,6 +324,16 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv, 
		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;

		}

	} else if (tun->flags & TUN_NOCHECKSUM)

		skb->ip_summed = CHECKSUM_UNNECESSARY;



	switch (tun->flags & TUN_TYPE_MASK) {

	case TUN_TUN_DEV:

		if (tun->flags & TUN_NO_PI) {
@@ -337,8 +360,35 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun, struct iovec *iv, 
		break;

	};



	if (tun->flags & TUN_NOCHECKSUM)

		skb->ip_summed = CHECKSUM_UNNECESSARY;

	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;

		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->last_rx = jiffies;
@@ -384,6 +434,39 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun, 
		total += sizeof(pi);

	}



	if (tun->flags & TUN_VNET_HDR) {

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

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

			return -EINVAL;



		if (skb_is_gso(skb)) {

			struct skb_shared_info *sinfo = skb_shinfo(skb);



			/* This is a hint as to how much should be linear. */

			gso.hdr_len = skb_headlen(skb);

			gso.gso_size = sinfo->gso_size;

			if (sinfo->gso_type & SKB_GSO_TCPV4)

				gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;

			else if (sinfo->gso_type & SKB_GSO_TCPV6)

				gso.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;

			else

				BUG();

			if (sinfo->gso_type & SKB_GSO_TCP_ECN)

				gso.gso_type |= VIRTIO_NET_HDR_GSO_ECN;

		} else

			gso.gso_type = VIRTIO_NET_HDR_GSO_NONE;



		if (skb->ip_summed == CHECKSUM_PARTIAL) {

			gso.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;

			gso.csum_start = skb->csum_start - skb_headroom(skb);

			gso.csum_offset = skb->csum_offset;

		} /* else everything is zero */



		if (unlikely(memcpy_toiovec(iv, (void *)&gso, sizeof(gso))))

			return -EFAULT;

		total += sizeof(gso);

	}



	len = min_t(int, skb->len, len);



	skb_copy_datagram_iovec(skb, 0, iv, len);
@@ -598,6 +681,11 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr) 
	else

		tun->flags &= ~TUN_ONE_QUEUE;



	if (ifr->ifr_flags & IFF_VNET_HDR)

		tun->flags |= TUN_VNET_HDR;

	else

		tun->flags &= ~TUN_VNET_HDR;



	file->private_data = tun;

	tun->attached = 1;

	get_net(dev_net(tun->dev));
@@ -684,7 +772,8 @@ static int tun_chr_ioctl(struct inode *inode, struct file *file, 
		/* Currently this just means: "what IFF flags are valid?".

		 * This is needed because we never checked for invalid flags on

		 * TUNSETIFF. */

		return put_user(IFF_TUN | IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE,

		return put_user(IFF_TUN | IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE |

				IFF_VNET_HDR,

				(unsigned int __user*)argp);

	}

include/linux/if_tun.h

+2 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#define TUN_NO_PI	0x0040

#define TUN_ONE_QUEUE	0x0080

#define TUN_PERSIST 	0x0100	

#define TUN_VNET_HDR 	0x0200



/* Ioctl defines */

#define TUNSETNOCSUM  _IOW('T', 200, int)
@@ -48,6 +49,7 @@ 
#define IFF_TAP		0x0002

#define IFF_NO_PI	0x1000

#define IFF_ONE_QUEUE	0x2000

#define IFF_VNET_HDR	0x4000



/* Features for GSO (TUNSETOFFLOAD). */

#define TUN_F_CSUM	0x01	/* You can hand me unchecksummed packets. */

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