ethtool is useful for setting (some) device fields, but it's
root-only. Finer feature control is available through a tun-specific
ioctl.
(Includes Mark McLoughlin <markmc@xxxxxxxxxx>'s fix to hold rtnl sem).
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
---
drivers/net/tun.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/if_tun.h | 7 +++++++
2 files changed, 56 insertions(+)
diff -r e08e6c5130ff drivers/net/tun.c
--- a/drivers/net/tun.c Thu Jun 26 00:17:07 2008 +1000
+++ b/drivers/net/tun.c Thu Jun 26 00:21:11 2008 +1000
@@ -596,6 +596,46 @@ static int tun_set_iff(struct net *net,
return err;
}
+/* 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)
+{
+ unsigned int 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));
+
+ if (arg & TUN_F_CSUM) {
+ features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;
+ arg &= ~TUN_F_CSUM;
+
+ if (arg & (TUN_F_TSO4|TUN_F_TSO6)) {
+ if (arg & TUN_F_TSO_ECN) {
+ features |= NETIF_F_TSO_ECN;
+ arg &= ~TUN_F_TSO_ECN;
+ }
+ if (arg & TUN_F_TSO4)
+ features |= NETIF_F_TSO;
+ if (arg & TUN_F_TSO6)
+ features |= NETIF_F_TSO6;
+ arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
+ }
+ }
+
+ /* This gives the user a way to test for new features in future by
+ * trying to set them. */
+ if (arg)
+ return -EINVAL;
+
+ dev->features = features;
+ if (old_features != dev->features)
+ netdev_features_change(dev);
+
+ return 0;
+}
+
static int tun_chr_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg)
{
@@ -699,6 +739,15 @@ static int tun_chr_ioctl(struct inode *i
tun->debug = arg;
break;
#endif
+
+ case TUNSETOFFLOAD:
+ {
+ int ret;
+ rtnl_lock();
+ ret = set_offload(tun->dev, arg);
+ rtnl_unlock();
+ return ret;
+ }
case SIOCGIFFLAGS:
ifr.ifr_flags = tun->if_flags;
diff -r e08e6c5130ff include/linux/if_tun.h
--- a/include/linux/if_tun.h Thu Jun 26 00:17:07 2008 +1000
+++ b/include/linux/if_tun.h Thu Jun 26 00:21:11 2008 +1000
@@ -43,12 +43,19 @@
#define TUNSETLINK _IOW('T', 205, int)
#define TUNSETGROUP _IOW('T', 206, int)
#define TUNGETFEATURES _IOR('T', 207, unsigned int)
+#define TUNSETOFFLOAD _IOW('T', 208, unsigned int)
/* TUNSETIFF ifr flags */
#define IFF_TUN 0x0001
#define IFF_TAP 0x0002
#define IFF_NO_PI 0x1000
#define IFF_ONE_QUEUE 0x2000
+
+/* Features for GSO (TUNSETOFFLOAD). */
+#define TUN_F_CSUM 0x01 /* You can hand me unchecksummed packets. */
+#define TUN_F_TSO4 0x02 /* I can handle TSO for IPv4 packets */
+#define TUN_F_TSO6 0x04 /* I can handle TSO for IPv6 packets */
+#define TUN_F_TSO_ECN 0x08 /* I can handle TSO with ECN bits. */
struct tun_pi {
unsigned short flags;
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