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tun: Allow GSO using virtio_net_hdr
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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: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Max Krasnyansky <maxk@qualcomm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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@rustyrussell @davem330
rustyrussell authored and davem330 committed Jul 3, 2008
1 parent 5228ddc commit f43798c
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Showing 2 changed files with 94 additions and 3 deletions.
95 changes: 92 additions & 3 deletions drivers/net/tun.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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>

Expand Down Expand Up @@ -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)
Expand All @@ -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))
Expand All @@ -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) {
Expand All @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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));
Expand Down Expand Up @@ -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);
}

Expand Down
2 changes: 2 additions & 0 deletions include/linux/if_tun.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand All @@ -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. */
Expand Down

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