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net: tun: convert to hw_features
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This changes offload setting behaviour to what I think is correct:
 - offloads set via ethtool mean what admin wants to use (by default
   he wants 'em all)
 - offloads set via ioctl() mean what userspace is expecting to get
   (this limits which admin wishes are granted)
 - TUN_NOCHECKSUM is ignored, as it might cause broken packets when
   forwarded (ip_summed == CHECKSUM_UNNECESSARY means that checksum
   was verified, not that it can be ignored)

If TUN_NOCHECKSUM is implemented, it should set skb->csum_* and
skb->ip_summed (= CHECKSUM_PARTIAL) for known protocols and let others
be verified by kernel when necessary.

TUN_NOCHECKSUM handling was introduced by commit
f43798c:

    tun: Allow GSO using virtio_net_hdr

Signed-off-by: Michał Mirosław <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
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@osctobe @davem330
osctobe authored and davem330 committed Apr 20, 2011
1 parent 4710304 commit 8825537
Showing 1 changed file with 25 additions and 38 deletions.
63 changes: 25 additions & 38 deletions drivers/net/tun.c
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Original file line number Diff line number Diff line change
Expand Up @@ -123,6 +123,9 @@ struct tun_struct {
gid_t group;

struct net_device *dev;
u32 set_features;
#define TUN_USER_FEATURES (NETIF_F_HW_CSUM|NETIF_F_TSO_ECN|NETIF_F_TSO| \
NETIF_F_TSO6|NETIF_F_UFO)
struct fasync_struct *fasync;

struct tap_filter txflt;
Expand Down Expand Up @@ -451,12 +454,20 @@ tun_net_change_mtu(struct net_device *dev, int new_mtu)
return 0;
}

static u32 tun_net_fix_features(struct net_device *dev, u32 features)
{
struct tun_struct *tun = netdev_priv(dev);

return (features & tun->set_features) | (features & ~TUN_USER_FEATURES);
}

static const struct net_device_ops tun_netdev_ops = {
.ndo_uninit = tun_net_uninit,
.ndo_open = tun_net_open,
.ndo_stop = tun_net_close,
.ndo_start_xmit = tun_net_xmit,
.ndo_change_mtu = tun_net_change_mtu,
.ndo_fix_features = tun_net_fix_features,
};

static const struct net_device_ops tap_netdev_ops = {
Expand All @@ -465,6 +476,7 @@ static const struct net_device_ops tap_netdev_ops = {
.ndo_stop = tun_net_close,
.ndo_start_xmit = tun_net_xmit,
.ndo_change_mtu = tun_net_change_mtu,
.ndo_fix_features = tun_net_fix_features,
.ndo_set_multicast_list = tun_net_mclist,
.ndo_set_mac_address = eth_mac_addr,
.ndo_validate_addr = eth_validate_addr,
Expand Down Expand Up @@ -628,8 +640,7 @@ static __inline__ ssize_t tun_get_user(struct tun_struct *tun,
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:
Expand Down Expand Up @@ -1094,6 +1105,10 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
goto err_free_sk;
}

dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
TUN_USER_FEATURES;
dev->features = dev->hw_features;

err = register_netdevice(tun->dev);
if (err < 0)
goto err_free_sk;
Expand Down Expand Up @@ -1158,18 +1173,12 @@ static int tun_get_iff(struct net *net, struct tun_struct *tun,

/* This is like a cut-down ethtool ops, except done via tun fd so no
* privs required. */
static int set_offload(struct net_device *dev, unsigned long arg)
static int set_offload(struct tun_struct *tun, unsigned long arg)
{
u32 old_features, features;

old_features = dev->features;
/* Unset features, set them as we chew on the arg. */
features = (old_features & ~(NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST
|NETIF_F_TSO_ECN|NETIF_F_TSO|NETIF_F_TSO6
|NETIF_F_UFO));
u32 features = 0;

if (arg & TUN_F_CSUM) {
features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
features |= NETIF_F_HW_CSUM;
arg &= ~TUN_F_CSUM;

if (arg & (TUN_F_TSO4|TUN_F_TSO6)) {
Expand All @@ -1195,9 +1204,8 @@ static int set_offload(struct net_device *dev, unsigned long arg)
if (arg)
return -EINVAL;

dev->features = features;
if (old_features != dev->features)
netdev_features_change(dev);
tun->set_features = features;
netdev_update_features(tun->dev);

return 0;
}
Expand Down Expand Up @@ -1262,12 +1270,9 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,

case TUNSETNOCSUM:
/* Disable/Enable checksum */
if (arg)
tun->flags |= TUN_NOCHECKSUM;
else
tun->flags &= ~TUN_NOCHECKSUM;

tun_debug(KERN_INFO, tun, "checksum %s\n",
/* [unimplemented] */
tun_debug(KERN_INFO, tun, "ignored: set checksum %s\n",
arg ? "disabled" : "enabled");
break;

Expand Down Expand Up @@ -1316,7 +1321,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
break;
#endif
case TUNSETOFFLOAD:
ret = set_offload(tun->dev, arg);
ret = set_offload(tun, arg);
break;

case TUNSETTXFILTER:
Expand Down Expand Up @@ -1595,30 +1600,12 @@ static void tun_set_msglevel(struct net_device *dev, u32 value)
#endif
}

static u32 tun_get_rx_csum(struct net_device *dev)
{
struct tun_struct *tun = netdev_priv(dev);
return (tun->flags & TUN_NOCHECKSUM) == 0;
}

static int tun_set_rx_csum(struct net_device *dev, u32 data)
{
struct tun_struct *tun = netdev_priv(dev);
if (data)
tun->flags &= ~TUN_NOCHECKSUM;
else
tun->flags |= TUN_NOCHECKSUM;
return 0;
}

static const struct ethtool_ops tun_ethtool_ops = {
.get_settings = tun_get_settings,
.get_drvinfo = tun_get_drvinfo,
.get_msglevel = tun_get_msglevel,
.set_msglevel = tun_set_msglevel,
.get_link = ethtool_op_get_link,
.get_rx_csum = tun_get_rx_csum,
.set_rx_csum = tun_set_rx_csum
};


Expand Down

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